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CN120512811B - Ultrashort Beam Homogenization Transmission Line System and Method Based on Quad-Octopole Composite Magnet - Google Patents

Ultrashort Beam Homogenization Transmission Line System and Method Based on Quad-Octopole Composite Magnet

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Publication number
CN120512811B
CN120512811B CN202510554064.4A CN202510554064A CN120512811B CN 120512811 B CN120512811 B CN 120512811B CN 202510554064 A CN202510554064 A CN 202510554064A CN 120512811 B CN120512811 B CN 120512811B
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iron
composite
transmission line
homogenization
pole
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CN120512811A (en
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边天剑
刘蕴韬
管锋平
魏素敏
邢建升
安世忠
陆锦荣
黄宇卓
郑侠
王飞
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China Institute of Atomic of Energy
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China Institute of Atomic of Energy
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H7/00—Details of devices of the types covered by groups H05H9/00, H05H11/00, H05H13/00
    • H05H7/04—Magnet systems, e.g. undulators, wigglers; Energisation thereof
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H13/00—Magnetic resonance accelerators; Cyclotrons
    • H05H13/005—Cyclotrons
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H7/00—Details of devices of the types covered by groups H05H9/00, H05H11/00, H05H13/00
    • H05H7/001—Arrangements for beam delivery or irradiation
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H7/00—Details of devices of the types covered by groups H05H9/00, H05H11/00, H05H13/00
    • H05H7/001—Arrangements for beam delivery or irradiation
    • H05H2007/007—Arrangements for beam delivery or irradiation for focusing the beam to irradiation target

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Optics & Photonics (AREA)
  • Particle Accelerators (AREA)

Abstract

本发明提出了一种基于四八极复合磁铁的超短束流均匀化传输线系统及方法，该系统包括四八极复合磁铁以及系统，直线型和弯转型束流均匀化结构，用于束流均匀化传输线的二级铁；还包括基于上述均匀化结构和/或二极铁的超短直线型束流均匀化运输线、超短弯转型束流均匀化运输线、超短直线弯转复合型束流均匀化运输线、超短对称弯转型束流均匀化运输线；该方法包括：基于四八极复合铁的励磁电流调试方法以及直线线型和弯转型束流调试方法；本发明解决了传输线上包络最大的地方被占用、不能完全发挥出八极铁作用问题；解决了八极铁所在位置束流包络较小，对八级磁铁的场强度要求很高的问题；解决了传输线长度过长导致其周围屏蔽的土建越加昂贵的问题。

This invention proposes an ultrashort beam homogenization transmission line system and method based on a four-octet composite magnet. The system includes a four-octet composite magnet and a system, linear and curved beam homogenization structures, and a secondary iron for beam homogenization transmission lines. It also includes ultrashort linear beam homogenization transmission lines, ultrashort curved beam homogenization transmission lines, ultrashort linear-curved composite beam homogenization transmission lines, and ultrashort symmetrical curved beam homogenization transmission lines based on the aforementioned homogenization structures and/or the secondary iron. The method includes: an excitation current adjustment method based on the four-octet composite iron and linear and curved beam adjustment methods. This invention solves the problems of the largest envelope area on the transmission line being occupied, preventing the full utilization of the octet iron; it solves the problem of a small beam envelope at the location of the octet iron, requiring a high field strength from the octet magnet; and it solves the problem of excessively long transmission lines leading to increasingly expensive surrounding shielding structures.

Description

Ultra-short beam homogenization transmission line system and method based on four-eight-pole composite magnet
Technical Field
The invention belongs to the technical field of accelerator transmission lines, and particularly relates to an ultra-short beam homogenization transmission line system and method based on a quadrupoles composite magnet.
Background
The secondary particles generated by beam current extraction and target shooting of the accelerator are important ray sources required by many nuclear technology researches and applications. For example, in nuclear technology applications such as neutron imaging, boron neutron capture therapy, etc., based on high-flux proton accelerators, the accelerator produces a high-energy high-flux proton beam that passes through a transmission line and strikes a neutron target, producing high-flux neutrons.
The accelerator extraction beam is generally distributed approximately gaussian, with the highest particle density in the center of the cluster, and also causes local over-power and over-temperature on the neutron target, resulting in neutron target damage.
In order to solve the problem of uneven particle distribution, an octupole magnet is used on a beam transmission line to homogenize Gaussian-distributed beam, so that peak power density on a neutron target is reduced.
One of the difficulties in homogenizing a gaussian distributed beam using an octapole magnet is that the same octapole iron is mounted at different locations on the beam transmission line and functions differently, and only when the octapole iron is mounted at a location with a larger beam envelope, it provides the strongest homogenization effect. However, the place where the envelope of the prior art is the largest is usually occupied by the quadrupole magnetic field, as shown in fig. 6, the transmission lines of the prior art are arranged in the order of the quadrupole iron 1, the octopole iron 1, the quadrupole iron 2 and the octopole iron 2, since the octopole iron is focused first before homogenization (the effect of focusing is to allow the beam to pass through the round hole in the center of the octopole iron without striking the octopole iron), in order to ensure focusing, the positions of the octopole iron 1 and the octopole iron 2 must first select the waist position of the envelope in the X direction and the waist position included in the Y direction, but since the envelope of the quadrupole iron 1 in the Y direction is smaller at the waist position of the envelope in the X direction, the envelope of the quadrupole iron 2 in the X direction is smaller at the octopole iron 1, while the waist position of the octopole iron 1 in the X direction is ensured, and likewise, the envelope in the Y direction is smaller at the octopole iron 2 while the waist position of the octopole iron 2 is ensured. In summary, according to the conventional method, the beam envelope of the particles after passing through the quadrupole iron 1 and the quadrupole iron 2 is obviously reduced, so that the functions of the octopole iron 1 and the octopole iron 2 cannot be fully exerted.
Two difficulties in homogenizing Gaussian beam current by using an octupole magnet are that the field strength K value of the octupole magnet is very large because the beam current envelopes of the octupole iron 1 and the octupole iron 2 are small, and the too high magnetic field strength is difficult to achieve in engineering and too high in cost.
Three difficulties of using the octopole magnet to homogenize Gaussian beam are that if the octopole iron is used to achieve better beam homogenization effect, the placement position and the phase of the octopole magnet are strictly required, and the length of the transmission line is often tens of meters to meet the requirements. The diameter of the cyclotron is not more than 2 meters, and a beam line of more than ten meters is towed, which is equivalent to the fact that the accelerator is made small, and the longer the beam line, the more expensive the civil engineering of shielding around is. In short, the disadvantages of large occupied area, high cost and the like of the overlong transmission line cause great limitation on the use of the beam homogenization technology.
Disclosure of Invention
Aiming at the problems existing in the prior art, the invention provides an ultra-short beam homogenization transmission line system and method based on a quadrupolar-octapole composite magnet. The first aim is to solve the problem that when the prior art adopts discrete quadrupole iron and eight stages, the maximum envelope is occupied by the quadrupole magnetic field, so that the effect of the octapole iron can not be fully exerted; the second aim is to solve the problems that when the discrete quadrupole iron and the discrete octapole are adopted, the field intensity requirements on the octapole magnet are very high due to the fact that the beam envelopes of the positions of the octapole iron 1 and the octapole iron 2 are small, and the too high magnetic field intensity is too high in engineering cost and difficult to realize, and the third aim is to solve the problems that when the discrete quadrupole iron and the discrete octapole are adopted, the too long length of a transmission line causes the more expensive civil engineering of shielding around the transmission line, the large occupied area and the high cost.
The invention provides the following technical scheme for solving the technical problems:
the ultra-short beam homogenization transmission line system based on the four-eight-pole composite magnet is characterized by comprising a four-eight-pole composite magnet, a four-eight-pole composite magnet system, an ultra-short linear beam homogenization structure, an ultra-short bending transformation beam homogenization structure and secondary iron for an ultra-short symmetrical bending transformation beam homogenization transmission line;
the ultra-short linear beam homogenization transmission line also comprises an ultra-short linear beam homogenization transmission line based on the four-eight-pole composite magnet, the four-eight-pole composite magnet system and the ultra-short linear beam homogenization structure;
the ultra-short bent conversion type beam homogenization transmission line is based on the four-eight-pole composite magnet, the four-eight-pole composite magnet system and the ultra-short bent conversion type beam homogenization structure;
The ultra-short linear bending composite beam homogenization transmission line is based on the four-eight-pole composite magnet, the four-eight-pole composite magnet system, the ultra-short linear beam homogenization structure and the ultra-short bending composite beam homogenization structure;
The ultra-short symmetrical turning beam homogenization transmission line also comprises an ultra-short symmetrical turning beam homogenization transmission line based on the four-eight composite magnet, a four-eight composite magnet system, an ultra-short turning beam homogenization structure and secondary iron for the ultra-short symmetrical turning beam homogenization transmission line;
the four-eight-pole composite magnet is arranged on an ultra-short beam homogenization transmission line and is used for generating a large envelope in the Y direction at the position of the four-eight-pole composite magnet 1 together with the front four-stage iron, and generating a large envelope in the X direction at the position of the four-eight-pole composite magnet 2 together with the front four-stage iron of the four-eight-pole composite magnet 1, so that Gaussian beam homogenization is realized, the four-eight-pole composite magnet is arranged on the beam transmission line, the number of transmission elements can be reduced, and the length of the transmission line is shortened;
The four-pole and eight-pole composite magnet system comprises a composite magnet current control device, a composite magnet main power supply and four-pole and eight-pole composite irons, wherein the composite magnet current control device is used for controlling the four-pole field coil current output and eight-pole field coil current output of the composite magnet main power supply to the four-pole and eight-pole composite irons;
According to the ultra-short linear beam homogenization structure, two quadrupolar and octupolar compound magnets are used on a transmission line and respectively generate a quadrupole magnetic field and an octupolar magnetic field at the same time, so that the functions of quadrupole iron and octupolar iron can be realized at the same time by only installing one transmission element;
The ultra-short bent beam homogenizing structure realizes a bent beam homogenizing substructure and a symmetrical bent beam homogenizing substructure by using a piece of secondary iron and a plurality of four-eight-level composite irons on a transmission line, wherein the bent beam homogenizing substructure is used for realizing a bent beam homogenizing transmission line;
The two-stage iron for the ultra-short symmetrical turning beam homogenization transmission line is characterized in that the common two-stage iron is a two-stage iron with an outlet side provided with upper and lower symmetrical edge angles, and particularly, the beam inflow port side is a straight line, the beam outflow port side is a pair of upper and lower symmetrical oblique lines, the oblique directions of the upper and lower symmetrical oblique lines are the directions of the beam turning at the outlet side, and the connecting line between the circle centers of the upper and lower symmetrical oblique lines and the beam turning track and the beam at the position of the two-stage iron outlet forms an outlet edge angle of the two-stage iron;
the ultra-short linear beam homogenization transmission line is a linear beam homogenization transmission line comprising two pieces of quadrupoles of composite iron, and is sequentially provided with an accelerator outlet, a beam matching mechanism, the quadrupoles of composite iron 1, the quadrupoles of composite iron 2, a beam homogenization effect observation mechanism and a terminal along the beam direction;
The ultra-short bent beam homogenization transmission line is an ultra-short bent beam homogenization transmission line comprising two four eight-stage composite irons and one two-stage iron, wherein the ultra-short bent beam homogenization transmission line is an ultra-short bent beam homogenization transmission line A distributed along the beam direction or an ultra-short bent beam homogenization transmission line B distributed along the beam direction, the ultra-short bent beam homogenization transmission line A is sequentially provided with an accelerator outlet, a beam matching mechanism, four eight-stage composite irons 1, two-stage irons, four eight-stage composite irons 2, a beam matching and homogenization effect observation mechanism 1 and a terminal 1 along the beam outlet direction, and the ultra-short bent beam homogenization transmission line B is sequentially provided with the accelerator outlet, the beam matching mechanism, the four eight-stage composite irons 1, the two-stage irons, the four eight-stage composite irons 3, the beam matching and homogenization effect observation mechanism 2 and the terminal 2 along the beam outlet direction;
The ultra-short symmetrical bent beam homogenization transmission line is a symmetrical bent beam homogenization transmission line which respectively comprises two four eight-level composite irons and one common two-level iron, and consists of one common beam line and two branch beam lines;
The ultra-short straight line bent composite beam homogenization transmission line consists of a straight line beam homogenization transmission line containing two four eight-level composite irons and a bent beam homogenization transmission line containing two four eight-level composite irons and one two-level iron;
The ultra-short bent beam homogenization structure, the ultra-short bent beam homogenization transmission line, the ultra-short symmetrical bent beam homogenization transmission line and the ultra-short straight bent composite beam homogenization transmission line are overlapped by utilizing the common focusing effect of the four-eight pole composite iron 1 and the dipolar iron to generate a beam waist in the Y direction at the position close to the four-eight pole composite iron 2 or the four-eight pole composite iron 3, and the quadrupolar field of the dipolar iron and the four-eight pole composite iron 2 or the dipolar iron and the four-eight pole composite iron 3 are overlapped to generate an envelope size in the X direction on a target, so that the envelope sizes in the X direction and the Y direction are consistent;
The ultra-short linear beam homogenizing structure, the ultra-short bent-type beam homogenizing structure, the ultra-short linear beam homogenizing transmission line, the ultra-short bent-type beam homogenizing transmission line, the ultra-short linear bent-type composite beam homogenizing transmission line and the ultra-short symmetrical bent-type beam homogenizing transmission line are characterized in that at a first quadrupolar composite magnet, the beam envelope function in the Y direction or the X direction reaches a larger value, at a second quadrupolar composite magnet, the beam envelope function in the X direction or the Y direction reaches a larger value, and the phase of particles between two quadrupolar composite magnets and a target is moved Each close to an integer multiple of 180 degrees (0, 1,2, 3.).
Further, the ultra-short bent beam homogenization structure is sequentially provided with four-eight-level composite iron 1, two-level iron, four-eight-level composite iron 2 and/or four-eight-level composite iron 3 along the beam direction; the secondary iron is used for changing the beam direction of the beam line from a straight line into a bent line; the four-eight-level composite iron 1, the four-eight-level composite iron 2 and/or the four-eight-level composite iron 3 are used for respectively and simultaneously generating a quadrupole magnetic field and an octapole magnetic field, so that the functions of the quadrupole iron and the octapole iron can be simultaneously realized by only installing one transmission element; the bent beam homogenizing substructure comprises a symmetrical first bent beam homogenizing structure and a symmetrical second bent beam homogenizing structure, wherein the symmetrical first bent beam homogenizing structure is provided with the four-eight composite iron 1 at the upstream of the secondary iron, the four-eight composite iron 2 at the downstream of the secondary iron, the four-eight composite iron 1 at the downstream of the secondary iron, the four-eight composite iron 3 at the downstream of the secondary iron, the symmetrical first bent beam homogenizing structure and the symmetrical second bent beam homogenizing structure work in a time-sharing manner, the symmetrical first bent beam homogenizing structure is provided with the four-eight composite iron 1 at the upstream of the secondary iron, the four-eight composite iron 2 at the downstream of the secondary iron, the symmetrical second bent beam homogenizing structure is provided with the four-eight composite iron 1 at the downstream of the secondary iron, the symmetrical first bent beam homogenizing structure and the symmetrical second bent beam homogenizing structure work in a time-sharing manner based on the symmetrical bent beam homogenizing transmission line, the common bent beam on the symmetrical first bent beam homogenizing structure is provided with a side of a common straight line, the common bent beam on the side of the two sides of the symmetrical bent beam homogenizing structure is provided with a side of the common straight line, the common bent beam is provided with the two side edges of the common side of the two sides of the common bent beam homogenizing structure, the angle of the exit edge of the diode iron is formed by connecting the circle center of the upward-downward symmetrical oblique line and the beam deflection track to the beam at the exit of the diode iron, the focusing effect of the edge field of the diode iron is adjusted by changing the angle of the exit edge of the diode iron, and the four eight-level composite iron on two sides of the diode iron is matched with the envelope of the Y direction and the envelope of the X direction, so that ideal phase shift meeting the homogenization requirement is obtained;
The common transmission line of the ultra-short straight line bent composite beam homogenization transmission line is sequentially provided with an accelerator outlet, a beam matching mechanism, a four-eight-stage composite iron 1 and a four-eight-stage composite iron 2 along the beam direction, wherein the four-eight-stage composite iron 2 has no eight-stage field when being applied to a bent branch transmission line, the two branch transmission lines are a linear branch transmission line and a bent branch transmission line, the linear branch transmission line is provided with a beam homogenization effect observation mechanism and a terminal, the bent branch transmission line is provided with a second-stage iron, a four-eight-stage composite magnet 3, a beam matching and homogenization effect observation mechanism and a terminal, the common transmission line and the linear branch transmission line form a composite linear beam homogenization transmission line, the common transmission line and the bent branch transmission line form a composite bent beam homogenization transmission line, and the composite linear beam homogenization transmission line and the composite bent beam homogenization transmission line work in a time sharing mode, and the eight-stage composite iron 1, the four-eight-stage composite iron 2 and the bent composite beam homogenization transmission line simultaneously realize the simultaneous homogenization of the four-eight-stage composite iron 1, the four-eight-stage composite iron 2 and the eight-stage composite beam homogenization transmission element and the eight-stage composite iron element simultaneously;
The common beam line of the ultra-short symmetrical bent beam homogenization transmission line is sequentially provided with an accelerator outlet, a beam matching mechanism, four-eight-level composite iron 1 and two-level iron along the beam direction; the two branch beam lines are a first branch beam line and a second branch beam line; the first branch beam line is sequentially provided with four-eight-level composite iron 2, a beam matching and homogenizing effect observation mechanism 1 and a terminal 1; the second branch beam streamline is sequentially provided with four-eight-level composite iron 3, a beam matching and homogenizing effect observation mechanism 2 and a terminal 2, the shared beam streamline and the first branch beam streamline form a first bent beam homogenizing transmission line, the shared beam streamline and the second branch beam streamline form a second bent beam homogenizing transmission line, the first bent beam homogenizing transmission line and the second bent beam homogenizing transmission line work in a time sharing mode, the four-eight-level composite iron 1, the four-eight-level composite iron 2 and the four-eight-level composite iron 3 of the first bent beam homogenizing transmission line respectively generate a magnetic field and an eight-pole magnetic field, so that the effect of four-pole iron and eight-pole iron can be realized simultaneously only by installing one transmission element, the shared secondary iron is two-pole iron meeting the homogenization of symmetrical bent beam, the two-pole iron is symmetric up and down on the inlet side of the symmetrical bent beam, the outlet side of the symmetrical bent beam is the straight side of the symmetrical bent beam, the straight side of the symmetrical beam is the straight side of the symmetrical beam, the oblique side of the straight side of the symmetrical beam is formed by the straight side of the symmetrical beam, the oblique side of the straight side of the symmetrical beam is changed to the oblique side of the outlet of the symmetrical beam, the oblique side of the straight side of the symmetrical beam is formed by the oblique side of the straight side of the symmetrical beam, and the oblique side of the edge of the exit of the symmetrical beam, and the oblique side of the edge, of the edge, the edge, the, and the, and, the, and the envelope of the four-eight-level composite iron on two sides of the dipolar iron in the Y direction and the envelope of the four-eight-level composite iron in the X direction are matched, so that ideal phase shift meeting the homogenization requirement is obtained.
The four-eight-pole compound magnet comprises an inner layer, an outer layer, four-pole magnetic field excitation coils, four groups of four-pole magnetic field excitation coils, and four groups of four-pole magnetic field excitation coils, wherein the current directions of two adjacent pole heads are opposite, namely, the eight-pole magnetic field excitation coils are divided into two groups of 1, 3,5, 7 and 2 pole heads and 2, 4, 6 and 7, 8 pole heads, the excitation currents of the two groups of four-pole magnetic field coils are identical to the directions, the directions of the excitation currents of the two groups of four-pole magnetic field coils are opposite, the directions of the 1,2 pole heads and 3, 4 pole heads are opposite, and the directions of the 5, 6 pole heads and 7, 8 pole heads are opposite, so that the magnetic field is generated.
The composite magnet current control device of the four-eight pole composite magnet system comprises a coil current two-dimensional sampling point module, an experimental measurement preliminary magnetic field gradient three-dimensional curved surface sample library module, a magnetic field gradient three-dimensional curved surface sample library module refined by interpolation, a corresponding field gradient current curve solving module for inputting field gradients, a four/eight pole field gradient current curve intersection point solving module and a four/eight pole coil current outputting module;
the coil current two-dimensional sampling point establishing module is used for establishing a coil current two-dimensional data comparison table of quadrupole irons and octapole irons;
The experimental measurement preliminary establishes a magnetic field gradient three-dimensional curved surface sample library module, which performs magnetic field experimental measurement on composite iron by using current values of a coil current two-dimensional data comparison table to obtain four-pole and eight-pole magnetic field gradient measurement values which are in one-to-one correspondence with the two-dimensional current data comparison table so as to obtain a magnetic field gradient three-dimensional curved surface sample database;
The interpolation refinement magnetic field gradient three-dimensional curved surface sample library module is used for carrying out two-dimensional interpolation on the quadrupole field magnetic field gradient three-dimensional curved surface sample database and the octapole field magnetic field gradient three-dimensional curved surface sample database by using a cubic spline function and encrypting grid point densities;
The input field gradient solving corresponding field gradient current curve module is used for intersecting the input quadrupole field gradient and the octupole field gradient with a magnetic field gradient curved surface of the three-dimensional sample database to obtain two corresponding current curves; selecting a quadrupole field magnetic field gradient plane which is intersected with a curved surface of a quadrupole field magnetic field gradient three-dimensional curved surface sample database to obtain a current curve meeting the four-level field gradient;
The module for solving the intersection point of the four/eight-pole field gradient current curves is used for obtaining an intersection point of a current curve meeting the four-pole field gradient and a current curve meeting the eight-pole field gradient, and the intersection point is used as a solution of the composite iron excitation current;
And the output quadrupole/octapole coil current module outputs quadrupole field coil current and octapole field coil current to the quadrupole/octapole composite iron according to the solving of the composite iron exciting current.
Further, the ultra-short linear beam homogenizing structure, the ultra-short curved beam homogenizing structure, the ultra-short linear beam homogenizing transmission line, the ultra-short curved beam homogenizing transmission line, the ultra-short linear curved composite beam homogenizing transmission line, and the phase shift of particles of the ultra-short symmetrical curved beam homogenizing transmission line between two four-eight composite magnets and the targetEach approximately an integer multiple of 180 degrees (0, 1,2, 3.) means approximately but not equal to an integer multiple of 180 degrees, provided thatIs thatWith a remainder of 180 degrees,The value is generally less than +/-15 degrees.
Further, the transmission matrix between two octapole magnetic fields of the ultrashort linear beam homogenization structure, the ultrashort curved beam homogenization structure, the ultrashort linear beam homogenization transmission line, the ultrashort curved beam homogenization transmission line, the ultrashort linear curved composite beam homogenization transmission line and the ultrashort symmetrical curved beam homogenization transmission line is close to the unity matrix, namely, the phase movement between the front and rear four octapole composite magnets is controlled within a 30-degree range, the 30-degree range can greatly avoid the high-order nonlinear effect caused by the coupling of the two octapole magnets, and a better homogenization effect can be obtained.
Further, the expressions of the magnet strength k at the first four-eight-pole composite magnet and the second four-eight-pole composite magnet of the ultrashort linear beam homogenization structure, the ultrashort curved beam homogenization transmission line, the ultrashort linear curved composite beam homogenization transmission line, and the ultrashort symmetrical curved beam homogenization transmission line are as follows:
Let us say that the start point of the transport line is denoted as 0, the position of the first quadrupolar magnet is denoted as 1, the position of the second quadrupolar magnet is denoted as 2, the position at the end point, i.e. the position of the target, is denoted as 3, ux02 of the above formula (1) represents the phase shift of the particle in the x direction between positions 0 and 2, ux23 represents the phase shift of the particle in the x direction between positions 2 and 3, βx2 represents the envelope function in the x direction at position 2, uy01 of the above formula (2) represents the phase shift of the particle in the y direction between 0 and 1, uy13 represents the phase shift of the particle in the y direction between 1 and 3, βy1 represents the envelope function in the y direction at position 1.
Further, when the ultra-short bent beam homogenizing structure uses the bent beam homogenizing substructure or the symmetrical first bent beam homogenizing structure, the Y-direction or X-direction beam envelope function reaches a larger value at the four-eight-stage composite iron 1, the X-direction or Y-direction beam envelope function reaches a larger value at the four-eight-stage composite iron 2, and the phase of the particles between the four-eight-stage composite iron 1 and the four-eight-stage composite iron 2 and the target is shiftedRespectively close to integer multiple of 180 degrees (0, 1,2, 3.), the transmission matrix between the two octopole magnetic fields is close to the identity matrix, when using a bent beam homogenization substructure or a symmetrical second bent beam homogenization structure, the beam envelope function in Y direction or X direction reaches a larger value at the four octopole composite iron 1, the beam envelope function in X direction or Y direction reaches a larger value at the four octopole composite iron 3, the phase of the particles between the four octopole composite iron 1 and the four octopole composite iron 3 and the target is shiftedEach close to an integer multiple of 180 degrees (0, 1,2, 3.).
The two-stage iron is a common dipolar iron on an ultrashort symmetrical bent beam homogenization transmission line, the ultrashort symmetrical bent beam homogenization transmission line consists of a common transmission line and two branch transmission lines, the common transmission line is sequentially provided with an accelerator outlet, a beam matching mechanism, four-eight-stage composite iron 1 and two-stage iron along the beam direction, the common transmission line and the four-eight-stage composite iron 2 of a first branch transmission line, the beam matching and homogenization effect observation mechanism 1 and the terminal 1 form a first bent beam homogenization transmission line, the four-eight-stage composite iron 3, the beam matching and homogenization effect observation mechanism 2 and the terminal 2 of the common transmission line and a second branch transmission line form a second bent beam homogenization transmission line, and the first bent beam homogenization transmission line and the second bent beam homogenization transmission line work in a time-sharing manner;
The ultra-short symmetrical bent beam homogenization transmission line consists of a common transmission line and two branch transmission lines; the common transmission line is sequentially provided with an accelerator outlet, a beam matching mechanism, four-eight-level composite iron 1 and two-level iron along the beam direction; the four-eight-stage composite iron 2, the beam matching and homogenizing effect observation mechanism 1 and the terminal 1 of the shared transmission line and the first branch transmission line form a first bent beam homogenizing transmission line, the four-eight-stage composite iron 3, the beam matching and homogenizing effect observation mechanism 2 and the terminal 2 of the shared transmission line and the second branch transmission line form a second bent beam homogenizing transmission line, the first bent beam homogenizing transmission line and the second bent beam homogenizing transmission line work in a time sharing way, and the common diode iron is a diode iron with upper and lower symmetrical edge angles on an outlet side, specifically, the beam inlet side of the common diode iron is a straight line, the beam outlet side of the common diode iron is a pair of oblique lines which are symmetrical up and down, the oblique directions of the upper and lower symmetrical oblique lines are directions of the beams respectively bent at the outlet side, the connecting line of the center of the oblique lines of the upper and the lower symmetrical oblique lines and the beam bending rails to the beam at the outlet of the diode iron forms an edge angle, and the edge field focusing effect of the diode iron is adjusted by changing the size of the edge angle of the diode iron outlet, and the edge field focusing effect of the diode iron is matched with the edge angle of the diode iron in the Y direction of the four sides of the beam at the diode iron outlet, so that the ideal envelope direction of the eight sides of the common diode iron is matched with the ideal envelope direction of the eight sides of the beam.
Further, the ideal phase shift meeting the homogenization requirement is obtained by optimally designing the edge angle of the dipolar iron, namely, by adjusting the edge angle of the dipolar iron outlet, the phase difference from the first quadrupolar-octapolar composite iron to the Y direction of the target point is close to 180 degrees, the phase difference from the second quadrupolar-octapolar composite iron to the X direction of the target point is close to 0 degree, the phase difference between the two quadrupolar-octapolar composite irons in the X direction is smaller than 30 degrees, and the phase difference between the two quadrupolar-octapolar composite irons in the Y direction is smaller than 30 degrees;
The included angle formed by the circle centers of the beam deflection tracks and the connecting lines of the beam at the entrance and the exit of the dipolar iron is the deflection angle of the beam, and under the condition of a certain beam deflection angle, the larger the edge angle of the dipolar iron outlet is, the stronger the focusing of the dipolar iron outlet edge in the Y direction is, and the weaker the focusing of the dipolar iron outlet edge in the X direction is;
The edge field focusing effect of the dipolar iron is adjusted by changing the size of the edge angle of the exit of the dipolar iron, and the four eight-level composite iron on two sides of the dipolar iron is matched with the envelope of the Y direction and the envelope of the X direction, so that ideal phase shift meeting the homogenization requirement is obtained, namely, when the homogenization effect needs to strengthen focusing in the Y direction and weaken focusing in the X direction to obtain ideal phase shift meeting the homogenization requirement, the edge angle of the exit of the dipolar iron is increased under the condition that the beam deflection angle is certain;
the adjustable range of the edge angle of the outlet of the dipolar iron is more than or equal to 0 degrees and less than 90 degrees;
the adjustable range of the angle of the outlet edge of the dipolar iron is preferably 20-60 degrees;
For the first curved-conversion beam homogenization transmission line, the diode iron with upper and lower symmetrical edge angles at the outlet side is arranged between the four-eight-level composite iron 1 and the four-eight-level composite iron 2, and the conventional diode iron is replaced by the diode iron with upper and lower symmetrical edge angles at the upper outlet side of the ultra-short transmission line, so that phase shift matching and beam focusing under the condition of ultra-short transmission line are realized;
For the second bent beam homogenization transmission line, the diode iron with upper and lower symmetrical edge angles at the outlet side is arranged between the four-eight-stage composite iron 1 and the four-eight-stage composite iron 3, and the phase shift matching and the beam focusing under the condition of ultrashort transmission line are realized by using the diode iron with upper and lower symmetrical edge angles at the upper outlet side of the ultrashort transmission line instead of the conventional diode iron.
The exciting current adjusting method for the four/eight pole composite iron is characterized by comprising the following steps of:
step one, establishing a coil current two-dimensional data comparison table of quadrupole iron and octapole iron, wherein the coil current two-dimensional data comparison table is based on four/octapole composite iron;
step two, experimental measurement is carried out to obtain four-pole and eight-pole magnetic field gradient measured values which are in one-to-one correspondence with a two-dimensional current data comparison table, so as to obtain a three-dimensional curved surface sample database of the magnetic field gradient, wherein the three-dimensional curved surface sample database of the magnetic field gradient comprises a four-pole magnetic field gradient three-dimensional curved surface sample database and an eight-pole magnetic field gradient three-dimensional curved surface sample database;
Thirdly, performing two-dimensional interpolation on the quadrupole field magnetic field gradient three-dimensional curved surface sample database and the octapole field magnetic field gradient three-dimensional curved surface sample database by using a cubic spline function, and encrypting grid point densities;
Selecting a quadrupole field magnetic field gradient plane which is intersected with a curved surface of the quadrupole field magnetic field gradient three-dimensional curved surface sample database to obtain a current curve meeting the four-level field gradient;
step five, obtaining a current curve meeting the gradient of a four-level field and a current curve meeting the gradient of an eight-level field in a coil current two-dimensional data grid plane, and finally solving an intersection point of the two current curves;
And step six, solving the intersection point serving as the composite iron excitation current.
The method for debugging the linear beam homogenization transmission line is based on a four/eight pole composite iron, a four/eight pole composite iron system, an excitation current adjusting method based on the four/eight pole composite iron and an ultra-short linear beam homogenization transmission line, and is characterized in that the method for debugging comprises the following steps:
setting the current of a quadrupole field and an octupole field of the quadrupole iron and the two quadrupole composite irons to zero;
observing the envelope change of the beam current on the fluorescent target, and adjusting the quadrupole iron current in front of the tetraoctapole composite iron 1 to enable the beam current to form a waist in the X direction near the tetraoctapole composite iron 1;
observing the envelope change of the beam current on the fluorescent target, and adjusting the quadrupole iron current of the quadrupole iron 1 in front of the quadrupole iron 2 so that the beam current forms a waist in the Y direction near the quadrupole iron 2, and reserving the quadrupole field gradient of the quadrupole iron 1 at the moment;
fourth, adjusting the quadrupole iron current of the quadrupolar-octupolar composite iron 2 to enable the envelope of the X direction and the envelope of the Y direction of the beam current on the fluorescent target to be consistent, obtaining a round beam, and reserving the quadrupole field gradient of the quadrupolar-octupolar composite iron 2 at the moment;
Fifthly, adjusting an octupole field of the tetraoctupole composite iron 1 to adjust the homogenization effect of the beam current in the Y direction, and calculating to obtain intersection point currents simultaneously meeting the quadrupole field gradient and the octupole field gradient of the tetraoctupole composite iron 1 according to the quadrupole field gradient of the tetraoctupole composite iron 1 recorded in the third step and the current octupole field gradient of the tetraoctupole composite iron 1, and reserving the octupole field gradient of the tetraoctupole composite iron 1 at the moment;
Step six, if the homogenization change of the beam current is not obvious when the octupole field current of the tetraoctupole composite iron 1 is regulated, the quadrupole field gradient of the tetraoctupole composite iron 1 needs to be modified for phase shift matching, so that the Y-direction phase shift from the tetraoctupole composite iron 1 to a target is close to 180 degrees, namely, the intersection point current which simultaneously meets the quadrupole field gradient and the octupole field gradient of the tetraoctupole composite iron 1 is calculated according to the regulated quadrupole field gradient of the tetraoctupole composite iron 1 and the octupole field gradient reserved in the step five;
Seventhly, adjusting an octupole field of the tetraoctupole composite iron 2 to adjust the homogenization effect of the beam current in the X direction, and calculating to obtain intersection point currents simultaneously meeting the quadrupole field gradient and the octupole field gradient of the tetraoctupole composite iron 2 according to the quadrupole field gradient of the tetraoctupole composite iron 2 and the current octupole field gradient of the tetraoctupole composite iron 2 recorded in the fourth step, so as to keep the octupole field gradient of the tetraoctupole composite iron 2 at the moment;
And step eight, if the homogenization change of the beam current is not obvious when the current of the quadrupolar-octupolar composite iron 2 octupolar field is regulated, the beam envelope in the X direction at the quadrupolar-octupolar composite iron 2 needs to be increased.
The method for debugging the bent beam homogenization transmission line is based on a four/eight pole composite iron, a four/eight pole composite iron system, an excitation current adjusting method based on the four/eight pole composite iron and an ultrashort linear beam homogenization transmission line, and is characterized by comprising the following steps of:
setting the current of a quadrupole field and an octupole field of the quadrupole iron and the two quadrupole composite irons to zero;
Step two, adjusting the diode iron current to enable the beam spot center to be approximately aligned with the fluorescent target center;
thirdly, observing the envelope change of the beam current on the fluorescent target, and adjusting the quadrupole iron current in front of the tetraoctapole composite iron 1 to enable the beam current to form a waist in the X direction near the tetraoctapole composite iron 1;
observing the change of beam envelope on the fluorescent target, adjusting the quadrupolar field current of the quadrupolar compound iron 1 in front of the dipolar iron, and enabling the beam to form a waist in the Y direction near the quadrupolar compound iron 2 under the combined action of the fringe field of the dipolar iron and the quadrupolar field of the quadrupolar compound iron 1, so as to keep the quadrupolar field gradient of the quadrupolar compound iron 1 at the moment;
Fifthly, adjusting the quadrupole iron current of the quadrupolar-octapole composite iron 2 to ensure that the envelope of the X direction and the envelope of the Y direction of the beam current on the fluorescent target are consistent to obtain a round beam, adjusting the dipolar iron current again to align the beam spot center with the target center, and reserving the quadrupole field gradient of the quadrupolar-octapole composite iron 2 at the moment;
step six, adjusting the octupole field of the tetraoctupole composite iron 1 to adjust the homogenization effect of the beam current in the Y direction, and calculating to obtain the intersection point current simultaneously meeting the quadrupole field gradient and the octupole field gradient of the tetraoctupole composite iron 1 according to the quadrupole field gradient of the tetraoctupole composite iron 1 and the current octupole field gradient of the tetraoctupole composite iron 1 recorded in the step four, and reserving the octupole field gradient of the tetraoctupole composite iron 1 at the moment;
step seven, if the homogenization change of the beam current is not obvious when the octupole field current of the tetraoctupole composite iron 1 is regulated, the quadrupole field gradient of the tetraoctupole composite iron 1 needs to be modified for phase shift matching, so that the Y-direction phase shift from the tetraoctupole composite iron 1 to a target is close to 180 degrees, namely, the intersection point current which simultaneously meets the quadrupole field gradient and the octupole field gradient of the tetraoctupole composite iron 1 is calculated according to the regulated quadrupole field gradient of the tetraoctupole composite iron 1 and the octupole field gradient reserved in the step six;
Step eight, adjusting an octupole field of the tetraoctupole composite iron 2 to adjust the homogenization effect of the beam current in the X direction, and calculating to obtain intersection point current which simultaneously meets the quadrupole field gradient and the octupole field gradient of the tetraoctupole composite iron 2 according to the quadrupole field gradient of the tetraoctupole composite iron 2 recorded in the step five and the current octupole field gradient of the tetraoctupole composite iron 2, and reserving the octupole field gradient of the tetraoctupole composite iron 2 at the moment;
Step nine, if the homogenization change of the beam current is not obvious when the current of the quadrupolar-octupolar composite iron 2 octupolar field is regulated, the beam envelope in the X direction at the quadrupolar-octupolar composite iron 2 needs to be increased.
Advantageous effects of the invention
1. The invention relates to a linear beam homogenization transmission line containing two quadrupoles and octupoles, which adopts a method of jointly generating a large envelope by the quadrupoles and the quadrupoles, and solves the problem that the maximum envelope is occupied by a quadrupole magnetic field when the prior art adopts discrete quadrupoles and octupoles, so that the effect of the octupoles cannot be fully exerted.
2. The linear beam homogenization transmission line comprises two pieces of quadrupoles and octupoles, and the quadrupoles and octupoles are positioned at the large envelope, so that the requirement on the K value of the strength of the quadrupoles and octupoles of the ferromagnetism is reduced, and the problems that the field strength of the octupoles is very high and the field strength of the octupoles is too high in engineering cost and difficult to realize due to the fact that the beam envelopes of the positions of the octupoles 1 and 2 are smaller when the discrete quadrupoles and octupoles are adopted in the prior art are solved.
3. The invention comprises a linear beam homogenization transmission line of two quadrupoles and octupoles, a quadrupole magnetic field and an octupoles magnetic field are simultaneously generated in the aperture of the quadrupoles and octupoles, and the focusing and homogenization effects on the beam envelope are simultaneously realized, the composite iron is arranged on the beam transmission line, so that the number of transmission elements can be reduced, the length of the transmission line is shortened, and the problems that the more expensive, the large occupied area and the high cost are caused by the fact that the surrounding shielding civil engineering is due to the overlong length of the transmission line when the discrete quadrupole iron and eight stages are adopted are solved.
4. The invention comprises a linear beam homogenization transmission line of two quadrupoles and octupoles composite iron, which limits the phase movement of particles between the two quadrupoles and a targetThe magnetic field strength k1 and k2 values required by the first four-eight-pole composite magnet and the second four-eight-pole composite magnet are smaller, so that the homogenization effect is ensured, and meanwhile, the manufacturing difficulty and cost of the magnets are reduced.
5. The linear beam homogenization transmission line comprises two quadrupoles of composite iron, and the transmission matrix between two octupoles of magnetic fields is limited to be close to a unity matrix, namely, the phase movement between the front and rear quadrupoles of composite iron is controlled within 30 degrees, the 30-degree range can greatly avoid the high-order nonlinear effect caused by the coupling of the two octupoles of magnetic iron, and a better homogenization effect can be obtained.
Drawings
FIG. 1 is a schematic diagram of an ultra-short beam homogenization transmission line system based on a four-eight pole composite magnet;
FIG. 2a is a schematic diagram of a current control device for a four-pole and eight-pole composite magnet according to the present invention;
FIG. 2b is a novel four/eight pole composite iron model of the present invention;
FIG. 2c shows a four-eight pole composite magnet coil arrangement and current direction according to the present invention;
FIG. 2d is a schematic diagram of the current values of two sets of coils during magnetic field measurement according to the present invention;
FIG. 2e is a schematic diagram of the experimental measurement of corresponding magnetic field gradients of four octupole at different currents according to the present invention;
FIG. 2f is a graph of the density of encrypted grid points for two-dimensional interpolation using cubic spline functions in accordance with the present invention;
FIG. 2g is a schematic illustration of the intersection of a selected magnetic field gradient plane with a magnetic field gradient surface of a three-dimensional sample database in accordance with the present invention;
FIG. 2h is a schematic diagram of a current curve corresponding to a selected four/eight pole field according to the present invention;
FIG. 2i is a schematic diagram of a solution of the composite iron excitation current of the present invention;
FIG. 3 is a schematic diagram of an ultrashort linear beam homogenization structure according to the present invention;
FIG. 4 is a schematic diagram of the phase difference between two quadripolar composite irons and a target point (target) and the phase difference between two quadripolar composite irons according to the present invention;
FIG. 5a is a schematic diagram of an ultrashort bent beam homogenization structure according to the present invention;
FIG. 5b is a schematic diagram A of an ultrashort single-turn beam homogenization substructure A according to the present invention;
FIG. 5c is a schematic diagram B of an ultrashort single-turn beam homogenization substructure B according to the present invention;
FIG. 5d is a schematic diagram of an ultrashort symmetrical curved beam homogenization substructure according to the present invention;
FIG. 6a is a schematic diagram of a linear beam homogenization transmission line according to the present invention;
FIG. 6b is a schematic diagram of the maximum envelope positions of the four-eight pole composite iron 1, 2 of the linear beam homogenization transmission line of the present invention;
FIG. 6c is a schematic diagram of a linear beam homogenization transmission line-beam matching mechanism in accordance with the present invention;
FIG. 6d is a schematic diagram of a linear beam homogenization transmission line-beam homogenization observation mechanism according to the present invention;
FIG. 6e is a schematic diagram showing the comparison of the distribution states of particles before and after homogenization of the transmission line according to the present invention;
FIG. 7a is a schematic diagram of a beam homogenization transmission line according to the present invention;
FIG. 7b is a schematic diagram of the maximum envelope positions of the four-eight pole composite iron 1, 2 of the bent and transformed beam homogenization transmission line of the present invention;
FIG. 7c is a schematic diagram of a beam matching mechanism for homogenizing a transmission beam in accordance with the present invention;
FIG. 7d is a schematic diagram of a beam matching and homogenizing effect observation mechanism 1 for beam homogenizing transmission of the bent type of the present invention;
FIG. 7e is a schematic diagram showing the comparison of the distribution states of particles before and after homogenization of the curved beam homogenization transmission line according to the present invention;
FIG. 8a is a schematic diagram of a symmetrical bend-type beam homogenization transmission line according to the present invention;
FIG. 8b is a schematic diagram of the maximum envelope positions of the four-octupole composite irons 1 and 2 of the symmetrical bent and turned beam homogenization transmission line;
FIG. 8c is a schematic diagram of a symmetrical bend beam homogenization transmission harness flow matching mechanism according to the present invention;
FIG. 8d is a schematic diagram of a mechanism 1 for observing the beam matching and homogenizing effects of symmetrical curved beam homogenization according to the present invention;
FIG. 8e is a schematic diagram of a mechanism 2 for observing the beam matching and homogenizing effects of the symmetrical curved beam homogenizing of the present invention;
FIG. 8f is a schematic diagram showing the comparison of the distribution states of particles before and after homogenization of the symmetrical bend beam homogenization transmission line according to the present invention;
FIG. 9a is a schematic diagram of an ultra-short straight-line bent composite beam homogenization transmission line according to the present invention;
fig. 9b is a schematic diagram of the maximum envelope positions of the composite linear transmission line quadrupolar and octupolar composite irons 1 and 2 according to the present invention;
Fig. 9c is a schematic diagram of the maximum envelope positions of the four-eight pole composite iron 1 and 3 of the composite bending transmission line according to the present invention;
FIG. 9d is a schematic diagram of an ultra-short straight line bent composite transmission line matching mechanism according to the present invention;
FIG. 9e is a schematic diagram of a homogenizing effect observation mechanism of the composite bend-to-turn beam homogenizing transmission line of the present invention;
FIG. 9f is a schematic diagram of a homogenizing effect observation mechanism of a composite linear beam homogenizing transmission line of the present invention;
FIG. 9g is a front-to-back comparison of the homogenization of the composite bend-to-beam homogenization transmission line of the present invention;
FIG. 9h is a graph showing the comparison of the homogenization front and back of the composite linear beam homogenization transmission line of the present invention;
FIG. 10 is a schematic diagram of a secondary iron of the present invention for an ultra-short symmetrical curved beam homogenization transmission line;
FIG. 11 is a flow chart of a linear beam homogenization adjustment method based on a quadrupolar-octapole composite magnet;
FIG. 12 is a flow chart of a method for homogenizing and debugging a bent beam flux based on a quadrupolar-octapole composite magnet;
FIG. 13 is a diagram of the beam envelope at a quadrupole iron and an octapole iron based discrete components of the prior art;
FIG. 14 is a diagram showing the position of each element of an ultra-short linear beam homogenization transmission line according to the present invention;
FIG. 15 is a diagram showing the positions of the elements of an ultra-short bend beam homogenization transmission line according to the present invention;
FIG. 16 is a diagram showing the positions of the elements of an ultra-short symmetrical bend-to-turn beam homogenization transmission line according to the present invention;
Fig. 17 is a position diagram of each element of an ultra-short straight-line bent composite beam homogenization transmission line according to the present invention.
Detailed Description
The innovation point of the invention is as follows:
One innovation point is that the invention provides a four-eight pole composite iron. The quadrupolar and octapolar iron of the discrete components shown in fig. 13 are replaced by quadrupolar and octapolar composite iron as shown in fig. 2a, 2b, 2 c. One of the effects is that a quadrupole magnetic field and an octapole magnetic field are generated in the aperture of the quadrupolar and octapole composite iron after the composition, and the effects are shown in figures 6b, 7b, 8b and 9b, wherein the quadrupolar iron and the octapole iron share the positions of the Y-direction and the X-direction large envelopes, so that the positions of the Y-direction or the X-direction large envelopes can be shared, the quadrupolar and octapole composite iron 1 and the quadrupolar iron in front of the quadrupolar and octapole composite iron are symbiotic with the Y-direction large envelopes, the quadrupolar and octapole composite iron 2 and the quadrupolar and octapole iron in front of the quadrupolar and octapole composite iron 1 are symbiotic with the X-direction large envelopes, and the octupolar and octapole iron in the quadrupolar and tetraoctapole composite iron 2 are distributed at the positions of the large envelopes, so that a good beam homogenization effect can be realized, namely the focusing and homogenizing effect on the beam envelope can be realized simultaneously. Compared with the prior art of fig. 13, since the prior art is that the quadrupolar iron and the octupole iron are separately distributed, the octupole iron cannot change the envelope like the quadrupolar iron, namely cannot be symbiotic with the prior quadrupolar iron to form a large envelope, the envelopes of the positions Y and X of the separately distributed octupole iron are smaller, and therefore, the homogenization effect is poor. The composite iron is arranged on the beam transmission line, so that the number of transmission elements can be reduced, the length of the transmission line is shortened, the engineering cost of the beam transmission line is reduced, the number of the transmission elements is reduced, quadrupole iron is saved, and a plurality of components required to be added on the transmission line for achieving the same effect homogenization are also saved.
The second innovation point is that a four/eight pole composite magnet current control system and a four/eight pole composite iron excitation current design method are invented. The design difficulty of the first and the fourth/eighth pole compound iron exciting currents is that a coupling relation exists between multipolar magnetic fields generated by two groups of coils of the fourth/eighth pole compound iron, the coupling relation means that the current of the four-pole field or the eighth pole field coils is changed, and the original four-pole magnetic field gradient and the eighth pole magnetic field gradient of the magnet are changed at the same time. Therefore, the one-to-one adjustment strategy of single type magnet current magnetic field gradient is not applicable any more, in the composite magnet, if the current of the four-pole field coil of the magnet is adjusted first, the current of the eight-stage field coil is adjusted when the four-pole field coil is adjusted to meet the use requirement, and once the current of the eight-stage field coil begins to change, the previously adjusted four-pole field gradient is changed, so that the four-pole field gradient does not meet the use requirement any more. Secondly, innovatively designs a four/eight-pole composite magnet current control system and a four/eight-pole composite iron excitation current design method, the system and the method solve the problem that coupling relation exists between multipole magnetic fields generated by two groups of coils of the four/eight-pole composite iron, and find a current intersection point which simultaneously meets the four-pole field gradient and the eight-pole field gradient. The system is shown in fig. 2a, and comprises a two-dimensional sampling point module based on coil current, an initial magnetic field gradient three-dimensional curved surface sample library module based on experimental measurement, a refined magnetic field gradient three-dimensional curved surface sample library module based on interpolation algorithm, a current curve module based on field gradient input and used for solving corresponding field gradient, a current curve intersection point module based on field gradient and used for outputting quadrupole/octal coil current. The design method of the four/eight-pole composite iron excitation current comprises the following steps:
step one, as shown in fig. 2d, a coil current two-dimensional data comparison table of quadrupole iron and octapole iron is established, wherein the coil current two-dimensional data comparison table is a coil current two-dimensional data comparison table based on four/octapole composite iron, the coil current two-dimensional data comparison table is shown in fig. 2d, the abscissa is four-level coil current, and the ordinate is four-level coil current.
Step two, as shown in fig. 2e, experimental measurement is carried out to obtain four-pole and eight-pole magnetic field gradient measurement values which are in one-to-one correspondence with a two-dimensional current data comparison table, so as to obtain a three-dimensional curved surface sample database of magnetic field gradients, wherein the three-dimensional curved surface sample database of the magnetic field gradients comprises a four-pole magnetic field gradient three-dimensional curved surface sample database and an eight-pole magnetic field gradient three-dimensional curved surface sample database;
The three-dimensional curved surface sample database is shown in fig. 2e, wherein the four-level coil current is taken as an X-axis coordinate, the eight-level coil current is taken as a Y-axis coordinate, and the magnetic field gradient is taken as a Z-axis coordinate.
Thirdly, as shown in fig. 2f, performing two-dimensional interpolation on the quadrupole field magnetic field gradient three-dimensional curved surface sample database and the octapole field magnetic field gradient three-dimensional curved surface sample database by using a cubic spline function, and encrypting grid point densities;
the effect of the above-described encryption grid point density is that the grid density in the X-axis, Y-axis, and Z-axis is increased as shown in fig. 2 f.
Selecting a quadrupole field magnetic field gradient plane which is intersected with the curved surface of the quadrupole field magnetic field gradient three-dimensional curved surface sample database to obtain a current curve meeting the four-level field gradient, and selecting an octant field magnetic field gradient plane which is intersected with the curved surface of the octant field magnetic field gradient three-dimensional curved surface sample database to obtain a current curve meeting the octant field gradient;
Step five, as shown in fig. 2h, obtaining a current curve meeting the four-level field gradient and a current curve meeting the eight-level field gradient in a coil current two-dimensional data grid plane, and finally solving an intersection point of the two current curves;
And step six, as shown in fig. 2i, the intersection point is used as the solution of the composite iron excitation current.
The third innovation point is that an ultrashort linear beam homogenizing structure, an ultrashort bent beam homogenizing structure and a secondary iron for an ultrashort symmetrical bent beam homogenizing transmission line are invented.
Firstly, as shown in fig. 3, the ultra-short linear beam homogenizing structure adopts two pieces of quadrupolar composite iron on a transmission line, wherein the quadrupolar composite iron 1 and the quadrupolar iron in front of the quadrupolar composite iron form a Y-direction large envelope, the large envelope is generated due to defocusing of the quadrupolar iron in front of the quadrupolar iron, the broken line is upward, the quadrupolar iron in back of the quadrupolar iron is focused, the broken line is downward, the intersection of the two broken lines forms a Y-direction large envelope, the quadrupolar iron 2 and the quadrupolar iron in front of the quadrupolar iron 2 form an X-direction large envelope, the large envelope is generated due to defocusing of the quadrupolar iron in front of the quadrupolar iron, the solid line is upward, the quadrupolar iron in back of the quadrupolar iron is focused, and the solid line is downward, and the intersection of the two solid lines forms an X-direction large envelope;
Secondly, as shown in fig. 5a, the ultra-short bent-conversion beam homogenizing structure adopts two pieces of quadrupolar compound iron and two dipoles of iron in the middle of the two pieces on a transmission line, wherein the dipoles are used for bending the direction of beam current, and the innovation point is that the quadrupolar iron current of the quadrupolar compound iron 1 is properly reduced at the current intersection point of the quadrupolar compound iron 1, and the fringe field focusing effect of the entrance of the dipoles behind the quadrupolar compound iron 1 and the quadrupolar iron focusing effect of the quadrupolar compound iron 1 are used for superposition to generate the waist in the Y direction of the quadrupolar compound iron 2. And at the current intersection point of the quadrupolar and octupolar composite iron 2, properly reducing the quadrupolar iron current of the quadrupolar and octupolar composite iron 2, and generating the envelope size of the X direction on the target by superposition of the dipolar iron outlet fringe field focusing effect behind the quadrupolar and octupolar composite iron 2, so that the envelope sizes of the X direction and the Y direction are consistent.
Third, as shown in fig. 10, the second-stage iron for the ultra-short symmetrical bent beam homogenizing transmission line is a common diode iron on the ultra-short symmetrical bent beam homogenizing transmission line, the common diode iron is a diode iron with an outlet side having an upper and a lower symmetrical edge angles, specifically, the beam inlet side is a straight line, the beam outlet side is a pair of vertical symmetrical oblique lines, the oblique directions of the vertical symmetrical oblique lines are the directions of the beams bent at the outlet side, the connection line between the center of the vertical symmetrical oblique lines and the beam bending track and the beam at the outlet of the diode iron forms the outlet edge angle of the diode iron, the edge field focusing effect of the diode iron is adjusted by changing the size of the outlet edge angle of the diode iron, and the four eight-stage composite irons at the two sides of the diode iron are matched with the envelope of the four eight-stage composite irons in the Y direction and the envelope in the X direction, so as to obtain the ideal phase shift meeting the homogenizing requirement.
The innovation point is that a balance point is found among the three parts of homogenizing the transmission line, avoiding nonlinear effect formed by coupling and shortening the transmission line. As shown in fig. 6b, 7b, 8b, 9b and 9c, the homogenization effect of the ultra-short bend beam homogenization transmission line is obvious, and the three are innovated from three aspects, which are not necessary, and the ideal homogenization effect can be achieved after mutual support:
the first aspect is to use two pieces of quadrupolar composite iron on a transmission line, namely, generating a large envelope in the Y direction of the quadrupolar composite iron 1 by using the quadrupolar iron in front of the quadrupolar composite iron 1 and the quadrupolar iron of the quadrupolar composite iron, and generating a large envelope in the X direction of the quadrupolar composite iron 2 by using the quadrupolar iron of the quadrupolar composite iron 1 in front of the quadrupolar composite iron 2 and the quadrupolar iron of the quadrupolar composite iron;
The second aspect solves the problem of optimizing homogenization effect by phase shift between the quadrupolar compound magnet 1 and the target Approximately an integer multiple of 180 degrees (0, 1,2, 3.) the phase shift between the quadrupolar compound magnet 2 and the targetApproximately an integer multiple of 0 degrees. The homogenization is best when approaching said 180 degrees and approaching said 0 degrees;
And in the third aspect, on the premise of ensuring homogenization, nonlinear effects formed by coupling are avoided, wherein the nonlinear effects are that when two pieces of quadrupolar ferroalloy are used together, if the two pieces of quadrupolar ferroalloy are improperly processed, nonlinear effect coupling effects are generated, and when nonlinear effect coupling occurs, particles are lost due to the increase of the amplitude of particles, and the homogenization effect is reduced due to the particle loss. Therefore, in order to avoid generating nonlinear effect coupling effect, the transmission matrix between the two octupole magnetic fields of the two quadrupole composite irons is close to an identity matrix, and the close identity matrix is that the phase difference between the first quadrupole composite iron (1 point) and the second quadrupole composite iron (2 points) is close to 0 degree and less than 30 degrees as shown in fig. 3, 4 and 5 a. The magnetic field intensity of the needed octapole magnet is smaller, and the homogenization degree is better because the nonlinear effect formed by coupling is smaller. The difference between the invention and the prior art is that the transmission matrix between the two octupole magnetic fields of the prior art is 'equal to the identity matrix' rather than 'close to the identity matrix', and the transmission matrix between the two octupole magnetic fields of the invention is 'close to the identity matrix' rather than 'equal to the identity matrix', namely the phase difference between the first four octupole composite iron (1 point) and the second four octupole composite iron (2 points) is approximately 0 degrees rather than equal to 0 degrees, less than 30 degrees rather than equal to 30 degrees. The meaning of the present invention using "close" rather than "equal" is to shorten the transmission line. If the method of 'equal to the unit matrix' is adopted, a plurality of components are added on the transmission line, and the transmission line is long when the number of components is increased. The invention adopts a method of 'enough' on the problem of 'nonlinear effect formed by avoiding coupling', when the phase difference between the first four-eight-stage composite iron (1 point) and the second four-eight-stage composite iron (2 points) is close to 0 degrees and less than 30 degrees, the length of a transmission line can be effectively shortened, the requirement of 'nonlinear effect formed by avoiding coupling' can be met, and a balance point is found among the three of homogenizing the transmission line, avoiding nonlinear effect formed by coupling and shortening the transmission line.
The innovation point is that a linear beam homogenization transmission line debugging method based on the quadrupoles composite iron is provided as shown in figure 11, and a bent beam homogenization transmission line debugging method based on the quadrupoles composite iron is provided as shown in figure 12;
1) The transmission line debugging difficulty based on the four-eight-pole composite iron is that compared with the transmission line debugging based on the single type four-pole iron current debugging and the single type eight-pole iron current debugging, the transmission line debugging based on the four-eight-pole composite iron has 2 difficulties,
One difficulty is that when the transmission line adopts the layout of the quadrupole iron and the octupole iron discrete elements, the distance between the quadrupole iron and the octupole iron discrete elements is relatively long, so that the octupole field current is not affected when the quadrupole field current is adjusted, and the quadrupole field current is not affected when the octupole field current is adjusted;
The four-pole and eight-pole composite iron is combined together, an aperture is shared, and a coupling relation exists between multipole magnetic fields generated by two groups of coils of the four-pole and eight-pole composite iron, wherein the coupling relation means that the current of a quadrupole field or an eight-pole field coil is changed, and the original quadrupole magnetic field gradient and the original eight-pole magnetic field gradient of the magnet are changed at the same time. Therefore, a one-to-one adjustment strategy for a single type of magnet current magnetic field gradient would no longer be applicable.
Another difficulty is that when the transmission line employs quadrupole irons, secondary irons and octapole irons which are discrete components, the length of the transmission line is not limited, and may be a ten-meter long transmission line, and although there is a fringe field focusing effect at the entrance and exit sides of the dipole irons, the fringe field focusing effect of the dipole irons has no effect on the envelope of the beam because the dipole irons are far from the front quadrupole irons. However, the length of the ultra-short transmission line based on the four-pole composite iron is only approximately one third of that of a conventional transmission line, the distance between the diode iron and the front four-eight-pole composite iron 1 and the distance between the diode iron and the rear four-eight-pole composite iron 2 are 0.6 m, under the condition of the ultra-short distance, the field focusing effect at the edge of the diode iron inlet can be overlapped with the focusing of the front four-eight-pole composite iron 1, the field focusing effect at the edge of the diode iron outlet can be overlapped with the focusing of the rear four-eight-pole composite iron 2, and therefore, the position of the phase waist of the four-eight-pole composite iron 1 in the X direction can be changed, and the envelope size in the X direction and the envelope size in the Y direction on a target are inconsistent.
2) Solution scheme
Firstly, in order to solve the problem that a coupling relation exists between multipolar magnetic fields generated by two groups of coils of four/eight pole composite iron, the debugging method adopts to debug near the intersection point of quadrupole iron current and eight-level iron current, firstly finds the intersection point, and then debugs near the intersection point;
Secondly, in order to solve the problems that the distance between the dipolar iron and the front and back quadrupoles is very short and the fringe field focusing effect of the dipolar iron and the front and back quadrupoles influences the beam envelope of the quadrupoles, the invention properly reduces the quadrupole iron current of the quadrupoles composite iron 1 at the current intersection point of the quadrupoles composite iron 1, and generates the Y-direction waist at the position of the quadrupoles composite iron 2 by superposing the fringe field focusing effect of the entrance of the dipolar iron behind the quadrupoles composite iron 1 and the quadrupole iron focusing effect of the quadrupoles composite iron 1. And at the current intersection point of the quadrupolar and octupolar composite iron 2, properly reducing the quadrupolar iron current of the quadrupolar and octupolar composite iron 2, and generating the envelope size of the X direction on the target by superposition of the dipolar iron outlet fringe field focusing effect behind the quadrupolar and octupolar composite iron 2, so that the envelope sizes of the X direction and the Y direction are consistent.
Based on the principle, the invention designs an ultra-short beam homogenization transmission line system based on a four-eight-pole composite magnet, which is shown in figure 1 and is characterized in that the transmission line system comprises a four-eight-pole composite magnet, a four-eight-pole composite magnet system, an ultra-short linear beam homogenization structure, an ultra-short bending beam homogenization structure and secondary iron for an ultra-short symmetrical bending beam homogenization transmission line;
as shown in fig. 6a, the ultra-short linear beam homogenization transmission line further comprises an ultra-short linear beam homogenization transmission line based on the four-eight-pole composite magnet, the four-eight-pole composite magnet system and the ultra-short linear beam homogenization structure;
as shown in fig. 7a, the ultra-short bent beam homogenization transmission line further comprises an ultra-short bent beam homogenization structure based on the four-eight-pole composite magnet, the four-eight-pole composite magnet system and the ultra-short bent beam homogenization structure;
As shown in fig. 8a, the ultra-short symmetrical turning beam homogenization transmission line further comprises a second-stage iron based on the four-eight pole composite magnet, the four-eight pole composite magnet system, the ultra-short turning beam homogenization structure and the ultra-short symmetrical turning beam homogenization transmission line;
As shown in fig. 9a, the ultra-short linear bending composite beam homogenization transmission line further comprises an ultra-short linear bending composite beam homogenization transmission line based on the four-eight-pole composite magnet, the four-eight-pole composite magnet system, the ultra-short linear beam homogenization structure and the ultra-short bending composite beam homogenization structure;
⑴ As shown in fig. 2b and 2c, the four-eight-pole composite magnet has eight pole heads in total, each pole head is provided with an inner layer current coil and an outer layer current coil along the radial direction at a position close to a large radius, the inner layer coil is an eight-pole magnetic field excitation coil, and the outer layer coil is a four-pole magnetic field excitation coil; the four-eight-pole composite magnet is arranged on an ultra-short beam homogenization transmission line and is used for generating a large envelope in the Y direction at the position of the four-eight-pole composite magnet 1 together with the four-pole iron in front of the ultra-short beam homogenization transmission line, and generating a large envelope in the X direction at the position of the four-eight-pole composite magnet 2 together with the four-pole iron of the four-eight-pole composite magnet 2 in front of the four-eight-pole composite magnet 2, so that the Gaussian distributed beam is homogenized, and the four-eight-pole composite magnet is arranged on the beam transmission line, so that the number of transmission elements can be reduced, and the length of the transmission line is shortened; the two adjacent pole heads of the outer layer are divided into four groups, namely 1 pole head, 2 pole head, 3 pole head, 4 pole head, 5 pole head, 6 pole head, 7 pole head and 8 pole head, wherein the exciting currents of the 1 pole head, the 3 pole head, the 5 pole head, the 7 pole head and the 2 pole head are identical, the 4 pole head and the 8 pole head, the exciting currents of the two groups of the coils are identical, but the current directions are opposite, so that an eight-pole magnetic field is generated, the four pole magnetic field exciting coils of the outer layer are divided into four groups, namely, the 1 pole head, the 2 pole head, the 3 pole head, the 4 pole head, the 5 pole head, the 6 pole head, the 7 pole head and the 8 pole head, wherein the 1 pole head, the 2 pole head and the symmetrically arranged 5 pole head, the 6 pole head are identical, the exciting currents of the 3 pole head, the 4 pole head and the symmetrically arranged 7 pole head are identical, the exciting currents of the two groups of the two coils are identical, the current directions of the 1 pole head, the 2 pole head and the 3 pole head, the 4 pole head coil are opposite, the four pole head coil are opposite, so that the magnetic field is generated, as shown in figure 2b, the four-eight-pole composite magnet is arranged on the ultra-short beam homogenization transmission line and is used for generating a large envelope in the Y direction at the position of the four-eight-pole composite magnet 1 together with the four-pole iron in front of the ultra-short beam homogenization transmission line, and generating a large envelope in the X direction at the position of the four-eight-pole composite magnet 2 together with the four-pole iron of the four-eight-pole composite magnet 2 in front of the four-eight-pole composite magnet 2, so that the Gaussian distributed beam is homogenized, and the four-eight-pole composite magnet is arranged on the beam transmission line, so that the number of transmission elements can be reduced, and the length of the transmission line is shortened;
⑵ As shown in fig. 2a, the four-pole and eight-pole composite magnet system comprises a composite magnet current control device, a composite magnet main power supply and four-pole and eight-pole composite irons, wherein the composite magnet current control device is used for controlling four-pole field coil current output and eight-pole field coil current output of the composite magnet main power supply to the four-pole and eight-pole composite irons, and the four-pole and eight-pole composite irons are used for simultaneously generating a dominant four-pole magnetic field and an eight-pole magnetic field, so that the functions of the four-pole irons and the eight-pole irons can be simultaneously realized by only installing one transmission element.
As shown in fig. 2a, the composite magnet current control device comprises a coil current two-dimensional sampling point module, a magnetic field gradient three-dimensional curved surface sample library module which is initially established by experimental measurement, a magnetic field gradient three-dimensional curved surface sample library module which is refined by interpolation, a corresponding field gradient current curve module which is solved by input field gradient, a four/eight-pole field gradient current curve intersection point module which is solved, and a four/eight-pole coil current output module;
As shown in fig. 2d, the coil current two-dimensional sampling point establishing module is used for establishing a coil current two-dimensional data comparison table of quadrupole irons and octapole irons;
As shown in fig. 2e, the experimental measurement preliminary establishes a magnetic field gradient three-dimensional curved surface sample library module, which performs magnetic field experimental measurement on the composite iron by using the current value of the coil current two-dimensional data comparison table, so as to obtain four-pole and eight-pole magnetic field gradient measurement values corresponding to the two-dimensional current data comparison table one by one, thereby obtaining a magnetic field gradient three-dimensional curved surface sample database;
As shown in fig. 2f, the module for refining the magnetic field gradient three-dimensional curved surface sample library by interpolation is used for performing two-dimensional interpolation on the quadrupole field gradient three-dimensional curved surface sample database and the octupole field gradient three-dimensional curved surface sample database by using a cubic spline function, and encrypting the grid point density;
As shown in fig. 2g and 2h, the input field gradient solving corresponding field gradient current curve module is used for intersecting the input quadrupole field gradient and the octupole field gradient with a magnetic field gradient curved surface of the three-dimensional sample database to obtain two corresponding current curves after intersecting; selecting a quadrupole field magnetic field gradient plane which is intersected with a curved surface of a quadrupole field magnetic field gradient three-dimensional curved surface sample database to obtain a current curve meeting the four-level field gradient;
As shown in fig. 2i, the module for solving intersection points of four/eight-pole field gradient current curves is configured to obtain intersection points of a current curve satisfying a four-pole field gradient and a current curve satisfying the eight-pole field gradient, and use the intersection points as solutions of composite iron excitation currents;
And the output quadrupole/octapole coil current module outputs quadrupole field coil current and octapole field coil current to the quadrupole/octapole composite iron according to the solution of the composite iron exciting current.
⑶ As shown in fig. 3, in the ultrashort linear beam homogenization structure, two quadrupolar and octupolar compound magnets are used on a transmission line, and respectively generate a quadrupole magnetic field and an octupolar magnetic field at the same time, so that the functions of quadrupole iron and octupole iron can be simultaneously realized by only installing one transmission element;
⑷ As shown in fig. 5a, the ultra-short bent beam homogenizing structure realizes a bent beam homogenizing substructure and a symmetrical bent beam homogenizing substructure by using a piece of secondary iron and a plurality of four-eight composite irons on a transmission line, wherein the bent beam homogenizing substructure is used for realizing a bent beam homogenizing transmission line;
The ultra-short bent beam homogenizing structure is sequentially provided with four-eight-level composite iron 1, two-level iron, four-eight-level composite iron 2 and/or four-eight-level composite iron 3 along the beam direction, wherein the two-level iron is used for changing the beam direction of a beam line from a straight line into bent type, and the four-eight-level composite iron 1, the four-eight-level composite iron 2 and/or the four-eight-level composite iron 3 are used for respectively generating a quadrupole magnetic field and an octapole magnetic field at the same time, so that the effect of the quadrupole iron and the octapole iron can be realized at the same time only by installing one transmission element;
The bent beam homogenization substructure is characterized in that a four-eight-level composite iron 1 is arranged on the upstream of a second-level iron, and a four-eight-level composite iron 2 or a four-eight-level composite iron 3 is arranged on the downstream of the second-level iron;
The symmetrical bent beam homogenization substructure comprises a symmetrical first bent beam homogenization structure and a symmetrical second bent beam homogenization structure, wherein the symmetrical first bent beam homogenization structure is provided with four-eight-stage composite iron 1 at the upstream of a second-stage iron and four-eight-stage composite iron 2 at the downstream of the second-stage iron, the symmetrical second bent beam homogenization structure is provided with four-eight-stage composite iron 1 at the upstream of the second-stage iron and four-eight-stage composite iron 3 at the downstream of the second-stage iron, and the symmetrical first bent beam homogenization structure and the symmetrical second bent beam homogenization structure work in a time-sharing manner;
The symmetrical turning beam homogenizing transmission line based on the symmetrical turning beam homogenizing substructure is a common diode iron on the ultra-short symmetrical turning beam homogenizing transmission line, wherein the common diode iron is a diode iron with upper and lower symmetrical edge angles at the outlet side, specifically, the beam inflow port side is a straight line, the beam outflow port side is a pair of vertical symmetrical oblique lines, the oblique directions of the vertical symmetrical oblique lines are the directions of the beam turning at the outlet side, the connecting line between the circle centers of the vertical symmetrical oblique lines and the beam turning track and the beam at the outlet of the diode iron forms a diode iron outlet edge angle, the edge field focusing effect of the diode iron is adjusted by changing the size of the diode iron outlet edge angle, and the four eight-level composite iron at two sides of the diode iron is matched with the envelope of the four eight-level composite iron in the Y direction and the envelope of the X direction, so that ideal phase shift meeting the homogenizing requirement is obtained.
When the bent beam homogenizing substructure or the symmetrical first bent beam homogenizing structure is used, the Y-direction or X-direction beam envelope function reaches a larger value at the four-eight-stage composite iron 1, and the X-direction or Y-direction beam envelope function reaches a larger value at the four-eight-stage composite iron 2, and the phase of the particles between the four-eight-stage composite iron 1 and the four-eight-stage composite iron 2 and the target is shiftedRespectively close to integer multiple of 180 degrees (0, 1,2, 3.), the transmission matrix between the two octopole magnetic fields is close to the identity matrix, when using a bent beam homogenization substructure or a symmetrical second bent beam homogenization structure, the beam envelope function in Y direction or X direction reaches a larger value at the four octopole composite iron 1, the beam envelope function in X direction or Y direction reaches a larger value at the four octopole composite iron 3, the phase of the particles between the four octopole composite iron 1 and the four octopole composite iron 3 and the target is shiftedRespectively, approximately an integer multiple of 180 degrees (0, 1,2, 3.);
Supplementary notes 1:
phase shift of the particles between the two quadrupolar and octupolar composite magnets and the target Approximately integer multiples of 180 degrees (0, 1,2, 3.), respectively) but not equal to 180 degrees, the principle of which is shown in equations (1) and (2):
In the formula (1), since Csc [ ux23] =1/sin [ ux23] of the molecule, sin [ ux23] tends to 0 and Csc [ ux23] tends to infinity when ux23 approaches 180, and in the same manner, csc [ ux13] =1/sin [ ux13] of the molecule of the formula (2), sin [ ux13] tends to 0 and Csc [ ux13] tends to infinity when ux13 approaches 180, the phase of the particles between the two quadrupolar complex magnets and the target is shifted Each approaching but not equal to an integer multiple of 180 degrees (0, 1,2, 3.).
⑸ As shown in fig. 8a and 10, the secondary iron used in the ultra-short symmetrical bent beam homogenization transmission line is a common diode iron on the ultra-short symmetrical bent beam homogenization transmission line, the common diode iron is a diode iron with an upper symmetrical edge angle and a lower symmetrical edge angle at the outlet side, specifically, the beam inlet side is a straight line, the beam outlet side is a pair of vertical symmetrical oblique lines, the oblique directions of the vertical symmetrical oblique lines are the directions of the beams bent at the outlet side, the connection line between the circle centers of the vertical symmetrical oblique lines and the beam bending tracks and the beam at the outlet of the diode iron forms the outlet edge angle of the diode iron, and the edge angle of the diode iron is optimally designed, so that the edge field focusing effect of the diode iron is utilized, and the envelope of four eight-stage composite irons at the two sides of the diode iron in the Y direction and the envelope of the X direction are matched, thereby obtaining the ideal phase shift meeting the homogenization requirement.
The edge angle of the diode iron is optimally designed, so that ideal phase shift meeting the homogenization requirement is obtained, namely, the phase difference from the first four-eight-pole composite iron to the Y direction of a target point is close to 180 degrees, the phase difference from the second four-eight-pole composite iron to the X direction of the target point is close to 0 degree, the phase difference of the two four-eight-pole composite irons in the X direction is smaller than 30 degrees, and the phase difference of the two four-eight-pole composite irons in the Y direction is smaller than 30 degrees;
The included angle formed by the circle centers of the beam deflection tracks and the connecting lines of the beam at the entrance and the exit of the dipolar iron is the deflection angle of the beam, and under the condition of a certain beam deflection angle, the larger the edge angle of the dipolar iron outlet is, the stronger the focusing of the dipolar iron outlet edge in the Y direction is, and the weaker the focusing of the dipolar iron outlet edge in the X direction is;
The edge field focusing effect of the dipolar iron is adjusted by changing the size of the edge angle of the exit of the dipolar iron, and the four eight-level composite iron on two sides of the dipolar iron is matched with the envelope of the Y direction and the envelope of the X direction, so that ideal phase shift meeting the homogenization requirement is obtained, namely, when the homogenization effect needs to strengthen focusing in the Y direction and weaken focusing in the X direction to obtain ideal phase shift meeting the homogenization requirement, the edge angle of the exit of the dipolar iron is increased under the condition that the beam deflection angle is certain;
the adjustable range of the edge angle of the outlet of the dipolar iron is more than or equal to 0 degrees and less than 90 degrees;
the adjustable range of the angle of the outlet edge of the dipolar iron is preferably 20-60 degrees;
For the first curved beam homogenization transmission line, the diode iron with upper and lower symmetrical edge angles at the outlet side is arranged between the four-eight-stage composite iron 1 and the four-eight-stage composite iron 2, and the conventional diode iron is replaced by the diode iron with upper and lower symmetrical edge angles at the upper outlet side of the ultra-short transmission line, so that phase shift matching and beam focusing under the condition of ultra-short transmission line are realized.
For the second bent beam homogenization transmission line, the diode iron with upper and lower symmetrical edge angles at the outlet side is arranged between the four-eight-stage composite iron 1 and the four-eight-stage composite iron 3, and the phase shift matching and the beam focusing under the condition of ultrashort transmission line are realized by using the diode iron with upper and lower symmetrical edge angles at the upper outlet side of the ultrashort transmission line instead of the conventional diode iron.
⑹ As shown in fig. 6a, the ultra-short linear beam homogenization transmission line is sequentially provided with an accelerator outlet, a beam matching mechanism, a quadrupolar composite iron 1, a quadrupolar composite iron 2, a beam homogenization effect observation mechanism and a terminal along the beam direction;
The beam matching mechanism is used for observing the initial state of the beam led out by the accelerator, adjusting the envelope size of the beam in the X or Y direction according to the initial state, and centering the beam center and the mechanical center of the beam pipeline;
The beam homogenization effect observation mechanism is used for observing the beam intensity, the weak beam shape and the strong beam section after being homogenized by the quadripole composite iron 1 and the quadripole composite iron 2.
The beam matching mechanism comprises a fluorescent target 1, a quadrupole magnet and a guide magnet, wherein the fluorescent target 1 provides a beam initial state for a tester, the quadrupole magnet is used for forming a large beam envelope in the Y direction or the X direction at the position of the quadrupoles composite iron 1, and the guide magnet is used for centering the beam center and the beam pipeline mechanical center.
The beam homogenization effect observation mechanism comprises a Faraday cylinder, a fluorescent target 2 and double wires, wherein the Faraday cylinder is used for measuring the homogenized beam intensity, the fluorescent target 2 is used for observing the homogenized weak beam shape, and the double wires are used for observing the homogenized strong beam shape.
⑺ As shown in fig. 7a, the ultra-short bent beam homogenization transmission line is an ultra-short bent beam homogenization transmission line comprising two four-eight-stage composite irons and one two-stage iron, wherein the ultra-short bent beam homogenization transmission line is an ultra-short bent beam homogenization transmission line A distributed along the beam direction or an ultra-short bent beam homogenization transmission line B distributed along the beam direction, the ultra-short bent beam homogenization transmission line A is sequentially provided with an accelerator outlet, a beam matching mechanism, four-eight-stage composite irons 1, two-stage irons, four-eight-stage composite irons 2, beam matching and homogenization effect observation mechanisms 1 and terminals 1 along the beam outlet direction, the ultra-short bent beam homogenization transmission line B is sequentially provided with an accelerator outlet, a beam matching mechanism, four-eight-stage composite irons 1, two-stage irons, four-eight-stage composite irons 3, beam matching and homogenization effect observation mechanisms 2 and terminals 2 along the beam outlet direction, the four-eight-stage composite irons 1, four-eight-stage composite irons 2 and four-eight-stage composite irons 3 simultaneously realize the simultaneous installation of magnetic fields of the four-eight-stage composite irons and the four-stage iron composite irons 1 and the four-eight-stage iron composite irons;
The beam matching mechanism is used for observing the initial state of the beam led out by the accelerator, adjusting the envelope size of the beam in the X or Y direction according to the initial state, and centering the beam center and the mechanical center of the beam pipeline;
The beam matching and homogenizing effect observing mechanism 1 or the beam matching and homogenizing effect observing mechanism 2 is used for adjusting the eccentricity of the beam after passing through the secondary iron and observing the beam strong and weak beam shape and the strong beam shape after being homogenized by the four-eight-stage composite iron 1 and the four-eight-stage composite iron 2.
The beam matching mechanism comprises a fluorescent target 1, a quadrupole magnet and a guide magnet, wherein the fluorescent target 1 provides a beam initial position for a tester, the quadrupole magnet is used for providing a beam envelope in the opposite direction for the four-eight-stage composite iron 1, and the guide magnet is used for adjusting the eccentricity of the beam.
The beam matching and homogenizing effect observation mechanism 1 comprises a guide magnet 2, a Faraday cylinder 1, a fluorescent target 2 and double wires 1, wherein the guide magnet 2 is used for centering the beam center and the beam pipeline mechanical center, the Faraday cylinder 1 is used for measuring the beam intensity after homogenization, the fluorescent target 2 is used for observing the weak beam shape after homogenization, the double wires 1 are used for observing the strong beam shape after homogenization, the beam matching and homogenizing effect observation mechanism 2 comprises a guide magnet 3, the Faraday cylinder 3, the fluorescent target 3 and the double wires 2, the guide magnet 3 is used for centering the beam center and the beam pipeline mechanical center, the Faraday cylinder 2 is used for measuring the beam intensity after homogenization, the fluorescent target 3 is used for observing the weak beam shape after homogenization, and the double wires 2 are used for observing the strong beam shape after homogenization.
⑻ As shown in fig. 8a, the ultra-short symmetrical bent beam homogenization transmission line is a symmetrical bent beam homogenization transmission line respectively comprising two four eight-stage composite irons and one common two-stage iron, and the symmetrical bent beam homogenization transmission line respectively comprising two four eight-stage composite irons and one common two-stage iron consists of one common transmission line and two symmetrical branch transmission lines;
As shown in fig. 8a, the common transmission line is sequentially provided with an accelerator outlet, a beam matching mechanism, a four-eight-stage composite iron 1 and a second-stage iron along the beam direction, the two branch transmission lines are a first branch transmission line and a second branch transmission line, the first branch transmission line is sequentially provided with a four-eight-stage composite iron 2, a beam matching and homogenizing effect observing mechanism 1 and a terminal 1, the second branch transmission line is sequentially provided with a four-eight-stage composite iron 3, a beam matching and homogenizing effect observing mechanism 2 and a terminal 2, the common transmission line and the first branch transmission line form a first bent beam homogenizing transmission line, the common transmission line and the second branch transmission line form a second bent beam homogenizing transmission line, and the first bent beam homogenizing transmission line and the second bent beam homogenizing transmission line work in a time sharing manner;
as shown in fig. 8c, the beam matching mechanism on the common transmission line is used for observing the initial state of the beam led out by the accelerator, adjusting the envelope size of the beam in the X or Y direction according to the initial state, and centering the beam center and the beam pipeline mechanical center;
As shown in fig. 8a, the four-eight-stage composite iron 1, the four-eight-stage composite iron 2 and the four-eight-stage composite iron 3 of the first bent beam homogenization transmission line and the second bent beam homogenization transmission line respectively generate a quadrupole magnetic field and an octapole magnetic field at the same time, so that the functions of the quadrupole iron and the octapole iron can be realized at the same time by only installing one transmission element;
As shown in fig. 8a, the beam matching and homogenizing effect observation mechanism 1 on the first branch transmission line is used for centering the beam center and the beam pipeline mechanical center, measuring the beam intensity after homogenization of the four-eight-stage composite iron 1 and the four-eight-stage composite iron 2, and observing the weak beam shape and the strong beam shape after homogenization;
as shown in fig. 8a, the beam matching and homogenizing effect observation mechanism 2 on the second branch transmission line is used for centering the beam center and the beam pipeline mechanical center, and measuring the beam intensity after homogenization of the four-eight-stage composite iron 1 and the four-eight-stage composite iron 3, and observing the weak beam shape and the strong beam shape after homogenization;
As shown in fig. 8a and 10, the common dipoles on the ultra-short symmetrical bent beam homogenization transmission line are the dipoles with upper and lower symmetrical edge angles on the outlet side, specifically, the beam inflow port side is a straight line, the beam outflow port side is a pair of up and down symmetrical oblique lines, the oblique directions of the up and down symmetrical oblique lines are the directions of the beams respectively bent at the outlet side, the connection line between the centers of the up and down symmetrical oblique lines and the beam bending track and the beam at the outlet of the dipoles forms the edge angle of the dipoles, the edge field focusing effect of the dipoles is adjusted by changing the size of the edge angle of the dipoles, and the four eight-stage composite irons at the two sides of the dipoles are matched with the envelope of the four eight-stage composite irons in the Y direction and the envelope of the X direction, so that ideal phase shift meeting the homogenization requirement is obtained.
As shown in fig. 8c, the beam matching mechanism on the common beam line is used for observing the initial state of the beam led out by the accelerator, adjusting the envelope size of the beam in the X or Y direction according to the initial state, and centering the beam center and the beam pipeline mechanical center;
As shown in fig. 8d, the beam matching and homogenizing effect observation mechanism 1 on the first branch beam line is used for centering the beam center and the beam pipeline mechanical center, measuring the beam intensity after homogenization of the four-eight-stage composite iron 1 and the four-eight-stage composite iron 2, and observing the weak beam shape and the strong beam shape after homogenization;
as shown in fig. 8e, the beam matching and homogenizing effect observation mechanism 2 on the second branch beam line is used for centering the beam center and the beam pipeline mechanical center, and measuring the beam intensity after homogenization of the four-eight-stage composite iron 1 and the four-eight-stage composite iron 3, and observing the weak beam shape and the strong beam shape after homogenization;
⑼ As shown in fig. 9a, the ultra-short straight bent composite beam homogenization transmission line is composed of a straight beam homogenization transmission line containing two four eight-stage composite irons and a bent beam homogenization transmission line containing two four eight-stage composite irons and one two-stage iron;
As shown in fig. 9a, the linear beam homogenization transmission line and the bent beam homogenization transmission line are composed of a shared transmission line and two branch transmission lines, wherein the shared transmission line is sequentially provided with an accelerator outlet, a beam matching mechanism, a four-eight-stage composite iron 1 and a four-eight-stage composite iron 2 along the beam direction, wherein the four-eight-stage composite iron 2 has no eight-stage field in a quadrupole field when applied to the bent branch transmission line, the two branch transmission lines are a linear branch transmission line and a bent branch transmission line, the linear branch transmission line is provided with a beam homogenization effect observation mechanism and a terminal, the bent branch transmission line is provided with a two-stage iron, a four-eight-stage composite iron 3, a beam matching and homogenization effect observation mechanism and a terminal, the shared transmission line and the linear branch transmission line form a composite linear beam homogenization transmission line, and the shared transmission line and the bent branch transmission line form a composite bent beam homogenization transmission line, and the composite linear beam homogenization transmission line works when the composite bent beam homogenization transmission line is in a time of the composite bent beam homogenization transmission line;
As shown in fig. 9a, the four-eight-stage composite iron 1, the four-eight-stage composite iron 2 and the four-eight-stage composite iron 1 and the four-eight-stage composite iron 3 of the composite linear beam homogenization transmission line respectively and simultaneously generate a quadrupole magnetic field and an octapole magnetic field, so that the functions of the quadrupole iron and the octapole iron can be simultaneously realized by only installing one transmission element;
As shown in fig. 5a, fig. 7b, fig. 8b, fig. 9c, the ultrashort bent beam homogenization structure, the ultrashort bent beam homogenization transmission line, the ultrashort symmetrical bent beam homogenization transmission line, and the ultrashort straight line bent composite beam homogenization transmission line are overlapped by using the common focusing effect of the tetraoctupole composite iron 1 and the diode iron to generate a beam waist in the Y direction near the tetraoctupole composite iron 2 or the tetraoctupole composite iron 3, and the quadrupole field of the diode iron and the tetraoctupole composite iron 2 or the diode iron and the tetraoctupole composite iron 3 is overlapped to generate an envelope size in the X direction on the target, so that the envelope sizes in the X direction and the Y direction are consistent;
As shown in FIG. 4, the ultra-short linear beam homogenizing structure, ultra-short bent beam homogenizing structure, ultra-short linear beam homogenizing transmission line, ultra-short bent beam homogenizing transmission line, ultra-short straight bent composite beam homogenizing transmission line, and ultra-short symmetrical bent beam homogenizing transmission line have a large value of Y-direction or X-direction beam envelope function at the first four-eight-pole composite magnet and a large value of X-direction or Y-direction beam envelope function at the second four-eight-pole composite magnet, and phase shift of particles between the two four-eight-pole composite magnets and the target Respectively, approximately an integer multiple of 180 degrees (0, 1,2, 3.), the transmission matrix between the two octopole magnetic fields being approximately unity, the phase shift between the two four octopole composite magnets and the targetEach approximately an integer multiple of 180 degrees (0, 1,2, 3.) means approximately but not equal to an integer multiple of 180 degrees, provided thatIs thatWith a remainder of 180 degrees,The value is generally smaller than +/-15 DEG, the transmission matrix is close to the identity matrix, namely the phase movement between the front and rear four-eight-pole compound magnets is controlled within a 30 DEG range, the 30 DEG range can greatly avoid the high-order nonlinear effect caused by the coupling of the two eight-pole magnets, and a better homogenization effect can be obtained;
the expression of the magnet strength k at the first four-eight-pole composite magnet and the second four-eight-pole composite magnet of the ultrashort linear beam homogenization structure, the ultrashort curved beam homogenization transmission line, the ultrashort linear curved composite beam homogenization transmission line and the ultrashort symmetrical curved beam homogenization transmission line is as follows:
Let the starting point of the transport line be 0, the position of the first four-eight pole magnet be 1, the position of the second four-eight pole magnet be 2, the position of the end point be 3, the position of the target be 3, ux02 of the above formula (1) represent the phase shift of the particle in the x direction between the positions 0 and 2, ux23 represent the phase shift of the particle in the x direction between the positions 2 and 3, βx2 represent the envelope function of the particle in the x direction at the position 2, uy01 of the above formula (2) represent the phase shift of the particle in the y direction between 0 and 1, uy13 represent the phase shift of the particle in the y direction between the positions 1 and 3, βy1 represent the envelope function of the particle in the y direction at the position 1;
supplementary explanation 2
As shown in FIG. 3, the derivation of equation (2) above for equation (1) is outlined below, in reference "Yosuke Yuri,Uniformization of the transverse beam profile by means of nonlinear focusing method[J].Physical Review Special Topics-Accelerators and Beams,2007.DOI:10.1103/physrevstab.10.104001.", which gives a single-direction octant field strength equation. This formula only considers one octapole magnet and the following transmission segment. To describe more precisely the relationship of the octupole magnetic field strength to the transmission line design, we extend the formula to take into account the effect of the matching section from the accelerator exit to the octupole iron on beam homogenization, involving parameters of ux02 (phase shift in x direction between positions 0 and 2), ux23 (phase shift in x direction between positions 2 and 3), uy01 (phase shift in x direction between positions 0 and 2), uy13 (phase shift in x direction between positions 2 and 3). Using the same "higher order transmission map" derivation method as in the reference, expression formula (1) and expression (2) of the magnet strength k at the first block of the four-eight-pole composite magnet, the second block of the four-eight-pole composite magnet are obtained.
The invention also designs an exciting current adjusting method for the four/eight pole composite iron, which is characterized by comprising the following steps:
step one, establishing a coil current two-dimensional data comparison table of quadrupole iron and octapole iron, wherein the coil current two-dimensional data comparison table is based on four/octapole composite iron;
the coil current two-dimensional data comparison table is shown in fig. 2d, the abscissa is four-level coil current, the ordinate is eight-level coil current, and the specific process is as follows:
1) The maximum requirement of the quadrupole field gradient is represented by Gq max, and the maximum requirement of the octupole field gradient is represented by Go max;
2) When the current of the quadrupole field coil is zero, the current when the octupole field coil generates Go max is the maximum working current I o of the octupole field coil, and when the current of the octupole field coil is zero, the current when the octupole field coil generates Gq max is the maximum working current I q of the quadrupole field coil;
3) The four-pole field coil maximum operating current I q and the eight-pole field coil maximum operating current I o are used as current data coverage boundaries of a coil current two-dimensional data comparison table, and are measured with equal interval current variation.
Step two, experimental measurement is carried out to obtain four-pole and eight-pole magnetic field gradient measured values which are in one-to-one correspondence with a two-dimensional current data comparison table, so as to obtain a three-dimensional curved surface sample database of the magnetic field gradient, wherein the three-dimensional curved surface sample database of the magnetic field gradient comprises a four-pole magnetic field gradient three-dimensional curved surface sample database and an eight-pole magnetic field gradient three-dimensional curved surface sample database;
The three-dimensional curved surface sample database is shown in fig. 2e, wherein four-level coil currents are used as X-axis coordinates, eight-level coil currents are used as Y-axis coordinates, and magnetic field gradients are used as Z-axis coordinates.
Thirdly, performing two-dimensional interpolation on the quadrupole field magnetic field gradient three-dimensional curved surface sample database and the octapole field magnetic field gradient three-dimensional curved surface sample database by using a cubic spline function, and encrypting grid point densities;
the effect of the above-described encryption grid point density is that the grid density in the X-axis, Y-axis, and Z-axis is increased as shown in fig. 10.
Selecting a quadrupole field magnetic field gradient plane which is intersected with a curved surface of the quadrupole field magnetic field gradient three-dimensional curved surface sample database to obtain a current curve meeting the four-level field gradient;
The current curve meeting the four-stage field gradient or the current curve meeting the eight-stage field gradient is that the magnetic field gradients of all points on the curve are equal, and the current values of all points on the curve correspond to one quadrupole field coil current and one octapole field coil current respectively.
Step five, obtaining a current curve meeting the gradient of a four-level field and a current curve meeting the gradient of an eight-level field in a coil current two-dimensional data grid plane, and finally solving an intersection point of the two current curves;
The method comprises the steps of obtaining a current curve meeting four-level field gradient and a current curve meeting eight-level field gradient in a coil current two-dimensional data grid plane, and finally solving the intersection point of the two current curves, namely, projecting the two current curves meeting the requirements of four-level field gradient and eight-level field gradient on the same coordinate system plane and obtaining the intersection point between the two current curves.
Step six, the intersection point is used as the solution of the composite iron excitation current, and the specific process is as follows:
1) Obtaining current curves meeting all four-level field gradients in a quadrupole field magnetic field gradient three-dimensional curved surface sample database, and obtaining current curves meeting all eight-level field gradients in an octupole field magnetic field gradient three-dimensional curved surface sample database;
2) Obtaining all intersection points of a current curve meeting the four-stage field gradient and a current curve meeting the eight-stage field gradient;
3) The four-pole field coil current and the eight-pole field coil current values of all the intersecting points are saved;
4) Inputting the current quadrupole field gradient requirement and the octupole field gradient requirement;
5) Finding a corresponding intersection point according to the current input quadrupole field gradient requirement and the current input octupole field gradient requirement;
6) The x coordinate of the intersection point represents the corresponding current value of the four-pole coil and the eight-pole coil of the four/eight-pole composite iron, and the y coordinate represents the corresponding current value of the eight-pole coil;
7) And inputting corresponding four-pole field coil and eight-pole field coil current values into the four/eight-pole composite magnet current control device, and finally finishing magnetic field gradient adjustment of the four/eight-pole composite magnet.
The invention also designs a linear beam homogenization transmission line debugging method, which is based on a four/eight pole composite iron, a four/eight pole composite iron system, an excitation current adjusting method based on the four/eight pole composite iron and an ultrashort linear beam homogenization transmission line;
The debugging method is characterized by comprising the following steps of:
setting the current of a quadrupole field and an octupole field of the quadrupole iron and the two quadrupole composite irons to zero;
observing the envelope change of the beam current on the fluorescent target, and adjusting the quadrupole iron current in front of the tetraoctapole composite iron 1 to enable the beam current to form a waist in the X direction near the tetraoctapole composite iron 1;
The specific process is as follows:
1) Gradually increasing quadrupole iron current in front of the quadrupolar-octapole composite magnet 1 from zero, observing that the envelope size of the beam current in the X direction is gradually reduced on the fluorescent target, and continuing to increase the quadrupole iron current until the envelope size of the beam current in the X direction is observed to be increased on the target, so that the beam current in the X direction becomes waist somewhere between the quadrupole iron and the target (close to the target);
2) To make the X-direction beam waist near the quadrupolar-octapole composite iron 1, the quadrupolar-iron current needs to be continuously increased, and the X-direction beam waist moves leftwards and stops when the quadrupolar-field current of the quadrupolar-octapole composite iron 1 is increased, and the X-direction beam envelope size on the fluorescent target is observed to be hardly changed, wherein the X-direction beam waist is near the quadrupolar-octapole composite iron 1;
supplementary notes a:
① The beam current waist in the X direction near the quadrupolar compound iron 1 is shown in fig. 6b, and the beam current waist in the Y direction near the quadrupolar compound iron 1 is a large envelope. The change of the size of the beam spot on the target cannot accurately judge whether the Y direction of the beam is a large envelope, taking the quadrupolar ferromagnet 1 as an example, the Y direction envelope is considered to be a large envelope when the size of the Y direction envelope is close to 2.5cm, the change of the Y direction of the beam on the target can be observed when the quadrupolar field current of the quadrupolar ferromagnet 1 is changed, however, even if the Y direction envelope is smaller than 2.5cm, for example, the change of the Y direction of the beam on the target can be observed when the quadrupolar field current of the quadrupolar ferromagnet 1 is changed when the Y direction envelope is 1cm, so that whether the Y direction envelope of the quadrupolar ferromagnet 1 is larger cannot be judged according to the change of the beam envelope on the target. And the quadrupolar iron in front of the quadrupolar composite iron 1 focuses in the X direction, defocuses in the Y direction, and when the beam current at the quadrupolar composite iron 1 is enveloped into waist in the X direction, the envelope in the Y direction is considered to be larger.
② The current of the quadrupolar iron in front of the quadrupolar composite iron 1 is used for adjusting the large envelope (waist forming in X direction) at the quadrupolar composite iron 1, the stronger the current of the quadrupolar iron in front, the higher the current of the quadrupolar iron in front is, the current of the quadrupolar composite iron in Y direction (dotted line) at the quadrupolar composite iron 1 is lifted, and the dotted line and the quadrupolar iron of the quadrupolar composite iron 1 (the quadrupolar iron of the quadrupolar composite iron 1 is in a focusing state in which the dotted line is inclined downwards at the moment) form the large envelope together.
Observing the envelope change of the beam current on the fluorescent target, and adjusting the quadrupole iron current of the quadrupole iron 1 in front of the quadrupole iron 2 so that the beam current forms a waist in the Y direction near the quadrupole iron 2, and reserving the quadrupole field gradient of the quadrupole iron 1 at the moment;
Supplementary notes B:
The method is characterized in that the reserved quadrupole field gradient is used for intersecting a rear octupole field gradient with a magnetic field gradient curved surface of a three-dimensional sample database, two corresponding current curves are obtained after intersecting, and the intersecting point of the two current curves is shown in a figure 2i, and the current value on the intersecting point meets the requirements of the quadrupole field gradient and the octupole field gradient, so that the coupling relation exists when the quadrupole iron is compounded together, the current of the magnet quadrupole field coil is firstly adjusted, the current of the octupole field coil is firstly adjusted to meet the use requirement when the quadrupole field gradient is adjusted, and once the current of the octupole field coil begins to change, the difficulty of the previously adjusted quadrupole field gradient is changed, and the bottleneck problem of beam homogenization debugging based on the quadrupole iron is solved.
The specific process is as follows:
1) Gradually increasing the quadrupolar field current of the quadrupolar compound magnet 1 from zero, observing that the envelope size of the beam current in the Y direction on the fluorescent target is gradually reduced, and continuously increasing the quadrupolar field current of the quadrupolar compound magnet 1 until the envelope size of the beam current in the Y direction on the target is observed to be increased, which indicates that the beam current in the Y direction becomes waist somewhere between the quadrupolar compound magnet 1 and the target (close to the target);
2) To make the Y-direction beam waist near the quadrupolar-octapole composite iron 2, the quadrupolar field current of the quadrupolar-octapole composite magnet 1 needs to be continuously increased, so that the Y-direction beam waist moves leftwards and stops when the Y-direction beam waist is increased to the situation that the quadrupolar field current of the quadrupolar-octapole composite iron 2 is increased, the Y-direction beam envelope size on a fluorescent target is hardly changed, and the Y-direction beam waist is near the quadrupolar-octapole composite iron 2 is observed;
fourth, adjusting the quadrupole iron current of the quadrupolar and octupolar compound iron 2to ensure that the envelope of the X direction and the envelope of the Y direction of the beam current on the fluorescent target are consistent to obtain a round beam, and reserving the quadrupole field gradient of the quadrupolar and octupolar compound iron 2 at the moment, wherein the specific process is as follows:
after the first to third steps, the envelope size of the beam in the X direction is ideally larger than the envelope size in the Y direction, the quadrupolar field current of the quadrupolar-octapolar composite magnet 2 is gradually increased from zero, the envelope size of the beam in the X direction is observed to be gradually reduced on the fluorescent target, and the quadrupolar field current of the quadrupolar-octapolar composite magnet 2 is continuously increased until the envelope size in the X direction is observed to be consistent with the envelope size in the Y direction on the target;
If the envelope size in X, Y direction does not meet the expectations after the steps one to three, the following adjustment methods should be adopted respectively:
1) If the X-direction size of the fluorescent target beam is larger than the target size, the quadrupole iron current in front of the four-eight-pole composite magnet 1 is reduced or the quadrupole field current of the four-eight-pole composite magnet 2 is increased, and if the X-direction size of the beam is smaller than the target size, the quadrupole iron current in front of the four-eight-pole composite magnet 1 is increased or the quadrupole field current of the four-eight-pole composite magnet 2 is reduced.
2) If the envelope size of the beam current Y direction on the fluorescent target is larger than the target size, the quadrupole field current of the four-eight-pole composite magnet 1 is reduced, and if the beam current Y direction size is smaller than the target size, the quadrupole field current of the four-eight-pole composite magnet 1 is increased.
The target size is specifically that a square target is usually arranged at the tail end of the transmission line, and if the side length of the target is L, the target size is that of a round beam, namely the diameter of the round beam is that of the round beam.
After adjustment, the method of claims 2 and 3 is required to reconfirm that the waist of the X-direction beam is near the quadrupolar-octapolar composite iron 1 and the waist of the Y-direction beam is near the quadrupolar-octapolar composite iron 2.
Supplementary notes C:
The fluorescent target according to the present invention is shown in fig. 6d, which means that the fluorescent target 2 is arranged at a position of 5.4 m of a transmission line having a length of about 6 m behind the quadrupolar composite iron 2.
Fifthly, adjusting an octupole field of the tetraoctupole composite iron 1 to adjust the homogenization effect of the beam current in the Y direction, and calculating to obtain intersection point current simultaneously meeting the quadrupole field gradient and the octupole field gradient of the tetraoctupole composite iron 1 according to the quadrupole field gradient of the tetraoctupole composite iron 1 and the current octupole field gradient of the tetraoctupole composite iron 1 recorded in the third step, and reserving the octupole field gradient of the tetraoctupole composite iron 1 at the moment, wherein the method comprises the following specific steps:
The brightness of the beam spot on the fluorescent target in the Y direction is uneven, if the brightness is shown as bright in the middle and dark at two sides of the Y direction of the beam spot on the fluorescent target, the eight-stage field current of the four-eight-pole composite magnet 1 is increased until the brightness of the beam spot on the fluorescent target in the Y direction is evenly distributed, the beam spot shape is changed from a circle to a rectangle, and if the brightness is shown as bright at two sides and dark in the middle of the Y direction of the beam spot on the fluorescent target, the eight-stage field current of the four-eight-pole composite magnet 1 is reduced until the brightness of the beam spot on the fluorescent target in the Y direction is evenly distributed, and the beam spot shape is changed from a circle to a rectangle.
Supplementary notes D:
The intersection current is calculated for the first time in step five. When the octupole field beam current is adjusted, the quadrupole field current adjusted in the front is changed, so that the problem that the quadrupole field current is changed is solved, the intersecting point current (the intersecting point current is obtained for the first time here), namely the current and octupole field gradients and the quadrupole field gradient reserved in the front are intersected with the magnetic field gradient curved surface of the three-dimensional sample database (the intersection of the plane and the curved surface is obtained for the first time here), two corresponding current curves are obtained after the intersection, the intersecting point after the two current curves are intersected is shown in fig. 2i, the current value on the intersecting point meets the requirement of the current octupole field gradient and also meets the requirement of the quadrupole field gradient, and thus, the problem that coupling relation exists when the quadrupole composite iron is compounded together is solved.
Step six, if the homogenization change of the beam current is not obvious when the octupole field current of the tetraoctupole composite iron 1 is regulated, the quadrupole field gradient of the tetraoctupole composite iron 1 needs to be modified for phase shift matching, so that the Y-direction phase shift from the tetraoctupole composite iron 1 to a target is close to 180 degrees, namely, the intersection point current which simultaneously meets the quadrupole field gradient and the octupole field gradient of the tetraoctupole composite iron 1 is calculated according to the regulated quadrupole field gradient of the tetraoctupole composite iron 1 and the octupole field gradient reserved in the step five;
supplementary notes E:
The intersection current is calculated a second time in step six. The first time of obtaining the intersection point current is when adjusting the octupole field of the quadrupole composite iron 1 to adjust the homogenization effect of the beam current in the Y direction, the second time of obtaining the intersection point current is because the homogenization change of the beam current is not obvious when adjusting the octupole field current of the quadrupole composite iron 1, and the quadrupole field gradient of the quadrupole composite iron 1 needs to be modified to carry out phase shift matching at the moment, because the quadrupole field gradient changes, the novel quadrupole field gradient and the octupole field gradient reserved in the step five are intersected with the magnetic field gradient curved surface of the three-dimensional sample database (the intersection of the plane and the curved surface is the second time), and two corresponding current curves are obtained after the intersection, the intersection point of the two current curves is shown in the figure 2i, and the current value on the intersection point meets the requirement of the current octupole field gradient at the present time, and also meets the requirement of the quadrupole field gradient, so that the problem of coupling relation exists when the quadrupole composite iron is composited together is solved.
The specific process is as follows:
1) If the brightness of the middle and two sides of the Y direction of the beam spot on the fluorescent target is almost unchanged, the phase shift of the Y direction from the four-eight-pole composite magnet 1 to the target is larger than the 180 DEG difference, if the middle of the Y direction of the beam spot on the fluorescent target is changed from light to dark, the two sides are changed from dark to light or the middle is changed from dark to light, the two sides are changed from light to dark, the phase shift of the Y direction from the four-eight-pole composite magnet 1 to the target is close to 180 DEG, the brightness is more particles, and the darkness is less particles;
2) When the brightness change of the beam spot in the Y direction on the fluorescent target is not obvious, the difference between the beam Y phase shift and 180 degrees between the four-eight-pole compound magnet 1 and the target is proved to be larger, the current phase shift is smaller than 180 degrees, the quadrupole iron current in front of the four-eight-pole compound magnet 1 is reduced, or the quadrupole iron current of the four-eight-pole compound magnet 1 is increased, the method is observed again according to the method in 1) after the operation is finished, if the brightness change of the beam spot in the Y direction on the fluorescent target is obvious when the field current of the eight-pole compound magnet 1 is increased, the explanation is correct, if the brightness of the beam spot in the Y direction on the fluorescent target is almost unchanged, the current phase shift is larger than 180 degrees, the quadrupole iron current in front of the four-eight-pole compound magnet 1 is increased, or the quadrupole iron current of the four-eight-pole compound magnet 1 is reduced, the method in 1) is observed again after the operation is finished, until the brightness change of the beam spot in the Y direction on the fluorescent target is obvious when the field current of the eight-pole compound magnet 1 is increased, and the phase shift is close to 180 degrees.
Seventhly, adjusting an octupole field of the tetraoctupole composite iron 2 to adjust the homogenization effect of beam current in the X direction, and calculating to obtain intersection point current simultaneously meeting the quadrupole field gradient and the octupole field gradient of the tetraoctupole composite iron 2 according to the quadrupole field gradient of the tetraoctupole composite iron 2 and the current octupole field gradient of the tetraoctupole composite iron 2 recorded in the fourth step, and reserving the octupole field gradient of the tetraoctupole composite iron 2 at the moment, wherein the specific process comprises the following steps:
The brightness of the beam spot on the fluorescent target in the X direction is uneven, if the brightness is shown as bright in the middle and dark at two sides in the X direction of the beam spot on the fluorescent target, the eight-stage field current of the four-eight-pole composite magnet 2 is increased until the brightness in the X direction of the beam spot on the fluorescent target is evenly distributed, the beam spot shape is changed into a square shape from a rectangular shape, and if the brightness is shown as bright at two sides and dark in the middle in the X direction of the beam spot on the fluorescent target, the eight-stage field current of the four-eight-pole composite magnet 2 is reduced until the brightness in the X direction of the beam spot on the fluorescent target is evenly distributed, and the beam spot shape is changed into a square shape from a rectangular shape.
Supplementary notes F:
the intersection current is calculated a third time in step seven. The third time is to obtain the difference between the intersecting point current and the previous second time, the previous second time is to adjust the octupole field of the quadrupole composite iron 1 when the intersecting point current is obtained, and the third time is to adjust the octupole field of the quadrupole composite iron 2;
The third time is to obtain the difference between the intersecting point current and the previous second time, the previous second time is to adjust the octupole field of the quadrupole composite iron 1 when the intersecting point current is obtained, and the third time is to adjust the octupole field of the quadrupole composite iron 2;
step eight, if the homogenization change of the beam current is not obvious when the current of the quadripole composite iron 2 octupole field is adjusted, the beam envelope in the X direction of the quadripole composite iron 2 needs to be increased, and the specific process is as follows:
1) If the brightness of the middle and two sides of the X direction of the beam spot on the fluorescent target is almost unchanged, the X direction beam envelope at the position of the four-eight-pole compound magnet 2 is smaller, if the middle of the X direction of the beam spot on the fluorescent target is darkened by light, the two sides are darkened by dark or the middle is darkened by dark, the two sides are darkened by light, the size of the X direction beam envelope at the position of the four-eight-pole compound magnet 2 is consistent with the homogenization requirement;
2) When the brightness change of the beam spot in the X direction on the fluorescent target is not obvious, the quadrupole iron current is increased, and whether the brightness change of the beam spot in the X direction on the fluorescent target is obvious or not is observed again according to the method in 1), if the brightness change of the beam spot is not obvious, the quadrupole iron current is continuously increased, and if the brightness change of the beam spot is obvious, the envelope size of the beam current in the X direction at the position of the quadrupolar compound magnet 2 meets the homogenization requirement, and the adjustment is completed.
Supplementary notes G:
In the step eight, the intersection point current is not continuously obtained, and the reason is that if the homogenization effect of the beam X direction on the target is not obvious when the octupole field current of the tetraoctupole composite iron 2 is regulated, the beam X direction envelope at the tetraoctupole composite iron 2 needs to be increased, but the X direction phase shift of the beam from the tetraoctupole composite iron 2 to the target is already close to 0 degrees, so the problem of increasing the beam X direction envelope at the tetraoctupole composite iron 2 cannot be solved by a phase shift method, the quadrupole iron current in front of the tetraoctupole composite iron 1 needs to be increased, and as seen in fig. 6b, the beam X direction envelope at the octupole composite iron 2 is increased until the homogenization change of the beam X direction on the target is obvious when the octupole field current of the tetraoctupole composite iron 2 is changed.
The invention also designs a bent beam homogenization transmission line debugging method, which is based on a four/eight pole composite iron, a four/eight pole composite iron system, a four/eight pole composite iron excitation current adjusting method and an ultra-short bent beam homogenization transmission line;
The debugging method is characterized by comprising the following steps of:
setting the current of a quadrupole field and an octupole field of the quadrupole iron and the two quadrupole composite irons to zero;
Step two, adjusting the diode iron current to enable the beam spot center to be approximately aligned with the fluorescent target center;
The specific process is as follows:
And in order to protect elements on the transmission line, calculating and setting an initial current value of the diode iron according to the current beam current parameter and the number of turns of the diode iron coil, observing whether the beam current appears on the fluorescent target, and if the beam current does not appear, adjusting the current value of the diode iron in the vicinity of the initial current value until the beam current appears on the fluorescent target. At the moment, the four-pole field current of the four-pole iron and the four-pole and eight-pole composite iron is zero, the beam envelope is large, and the beam is approximately aligned with the center of the target, so that the next step can be carried out;
thirdly, observing the envelope change of the beam current on the fluorescent target, and adjusting the quadrupole iron current in front of the tetraoctapole composite iron 1 to enable the beam current to form a waist in the X direction near the tetraoctapole composite iron 1;
The specific process is as follows:
1) Gradually increasing quadrupole iron current in front of the quadrupolar-octapole composite magnet 1 from zero, observing that the envelope size of the beam current in the X direction is gradually reduced on the fluorescent target, and continuing to increase the quadrupole iron current until the envelope size of the beam current in the X direction is observed to be increased on the target, so that the beam current in the X direction becomes waist somewhere between the quadrupole iron and the target (close to the target);
2) To make the X-direction beam waist near the quadrupolar-octapole composite iron 1, the quadrupolar-iron current needs to be continuously increased, and the X-direction beam waist moves leftwards and stops when the quadrupolar-field current of the quadrupolar-octapole composite iron 1 is increased, and the X-direction beam envelope size on the fluorescent target is observed to be hardly changed, wherein the X-direction beam waist is near the quadrupolar-octapole composite iron 1;
supplementary notes a:
① The beam current becomes waist in the X direction near the quadrupolar composite iron 1, and as shown in fig. 7b, the beam current becomes large envelope in the Y direction near the quadrupolar composite iron 1. The change of the size of the beam spot on the target cannot accurately judge whether the Y direction of the beam is a large envelope, taking the quadrupolar ferromagnet 1 as an example, the Y direction envelope is considered to be a large envelope when the size of the Y direction envelope is close to 2.5cm, the change of the Y direction of the beam on the target can be observed when the quadrupolar field current of the quadrupolar ferromagnet 1 is changed, however, even if the Y direction envelope is smaller than 2.5cm, for example, the change of the Y direction of the beam on the target can be observed when the quadrupolar field current of the quadrupolar ferromagnet 1 is changed when the Y direction envelope is 1cm, so that whether the Y direction envelope of the quadrupolar ferromagnet 1 is larger cannot be judged according to the change of the beam envelope on the target. And the quadrupolar iron in front of the quadrupolar composite iron 1 focuses in the X direction, defocuses in the Y direction, and when the beam current at the quadrupolar composite iron 1 is enveloped into waist in the X direction, the envelope in the Y direction is considered to be larger.
② The current of the quadrupolar iron in front of the quadrupolar composite iron 1 is used for adjusting the large envelope (waist forming in X direction) at the quadrupolar composite iron 1, the stronger the current of the quadrupolar iron in front, the higher the current of the quadrupolar iron in front is, the current of the quadrupolar composite iron in Y direction (dotted line) at the quadrupolar composite iron 1 is lifted, and the dotted line and the quadrupolar iron of the quadrupolar composite iron 1 (the quadrupolar iron of the quadrupolar composite iron 1 is in a focusing state in which the dotted line is inclined downwards at the moment) form the large envelope together.
Observing the change of beam envelope on the fluorescent target, adjusting the quadrupolar field current of the quadrupolar compound iron 1 in front of the dipolar iron, and enabling the beam to form a waist in the Y direction near the quadrupolar compound iron 2 under the combined action of the fringe field of the dipolar iron and the quadrupolar field of the quadrupolar compound iron 1, so as to keep the quadrupolar field gradient of the quadrupolar compound iron 1 at the moment;
The specific process is as follows:
1) Gradually increasing the quadrupolar field current of the quadrupolar compound magnet 1 from zero, observing that the envelope size of the beam current in the Y direction on the fluorescent target is gradually reduced, and continuously increasing the quadrupolar field current of the quadrupolar compound magnet 1 until the envelope size of the beam current in the Y direction on the target is observed to be increased, which indicates that the beam current in the Y direction becomes waist somewhere between the quadrupolar compound magnet 1 and the target (close to the target);
2) To make the Y-direction beam waist near the quadrupolar-octapole composite iron 2, the quadrupolar field current of the quadrupolar-octapole composite magnet 1 needs to be continuously increased, so that the Y-direction beam waist moves leftwards and stops when the Y-direction beam waist is increased to the situation that the quadrupolar field current of the quadrupolar-octapole composite iron 2 is increased, the Y-direction beam envelope size on a fluorescent target is hardly changed, and the Y-direction beam waist is near the quadrupolar-octapole composite iron 2 is observed;
Supplementary notes B:
The method is characterized in that the reserved quadrupole field gradient is used for intersecting a rear octupole field gradient with a magnetic field gradient curved surface of a three-dimensional sample database, two corresponding current curves are obtained after intersecting, and the intersecting point of the two current curves is shown in a figure 2i, and the current value on the intersecting point meets the requirements of the quadrupole field gradient and the octupole field gradient, so that the coupling relation exists when the quadrupole iron is compounded together, the current of the magnet quadrupole field coil is firstly adjusted, the current of the octupole field coil is firstly adjusted to meet the use requirement when the quadrupole field gradient is adjusted, and once the current of the octupole field coil begins to change, the difficulty of the previously adjusted quadrupole field gradient is changed, and the bottleneck problem of beam homogenization debugging based on the quadrupole iron is solved.
Fifthly, adjusting the quadrupole iron current of the quadrupolar-octapole composite iron 2 to ensure that the envelope of the X direction and the envelope of the Y direction of the beam current on the fluorescent target are consistent to obtain a round beam, adjusting the dipolar iron current again to align the beam spot center with the target center, and reserving the quadrupole field gradient of the quadrupolar-octapole composite iron 2 at the moment;
supplementary notes C:
The fluorescent target according to the present invention is shown in fig. 6d, which means that the fluorescent target 2 is arranged at a position of 5.4 m of a transmission line having a length of about 6 m behind the quadrupolar composite iron 2.
The specific process is as follows:
after the first to fourth steps, the envelope size of the beam in the X direction is ideally larger than the envelope size in the Y direction, the quadrupolar field current of the quadrupolar-octapolar composite magnet 2 is gradually increased from zero, the envelope size of the beam in the X direction is observed to be gradually reduced on a fluorescent target, and the quadrupolar field current of the quadrupolar-octapolar composite magnet 2 is continuously increased until the envelope size in the X direction is observed to be consistent with the envelope size in the Y direction on the target;
if the envelope size in X, Y directions does not meet the expectations after the first to fourth steps, the following adjustment methods should be adopted respectively:
1) If the X-direction size of the fluorescent target beam is larger than the target size, the quadrupole iron current in front of the four-eight-pole composite magnet 1 is reduced or the quadrupole field current of the four-eight-pole composite magnet 2 is increased, and if the X-direction size of the beam is smaller than the target size, the quadrupole iron current in front of the four-eight-pole composite magnet 1 is increased or the quadrupole field current of the four-eight-pole composite magnet 2 is reduced.
2) If the envelope size of the beam current Y direction on the fluorescent target is larger than the target size, the quadrupole field current of the four-eight-pole composite magnet 1 is reduced, and if the beam current Y direction size is smaller than the target size, the quadrupole field current of the four-eight-pole composite magnet 1 is increased.
The target size is specifically that a square target is usually arranged at the tail end of a transmission line, and if the side length of the target is L, the target size isI.e. the diameter of the round beam is
After the operation, the beam spot can be clearly observed on the target, and the diode iron current is adjusted again, so that the center of the beam spot is aligned with the center of the target. After adjustment, the waist of the X-direction beam is required to be reconfirmed to be near the quadrupolar-octapole composite iron 1 and the waist of the Y-direction beam is required to be near the quadrupolar-octapole composite iron 2 according to the methods of claims 2 and 3;
step six, adjusting the octupole field of the tetraoctupole composite iron 1 to adjust the homogenization effect of the beam current in the Y direction, and calculating to obtain the intersection point current simultaneously meeting the quadrupole field gradient and the octupole field gradient of the tetraoctupole composite iron 1 according to the quadrupole field gradient of the tetraoctupole composite iron 1 and the current octupole field gradient of the tetraoctupole composite iron 1 recorded in the step four, and reserving the octupole field gradient of the tetraoctupole composite iron 1 at the moment;
The specific process is as follows:
The brightness of the beam spot on the fluorescent target in the Y direction is uneven, if the brightness is shown as bright in the middle and dark at two sides of the Y direction of the beam spot on the fluorescent target, the eight-stage field current of the four-eight-pole composite magnet 1 is increased until the brightness of the beam spot on the fluorescent target in the Y direction is evenly distributed, the beam spot shape is changed from a circle to a rectangle, and if the brightness is shown as bright at two sides and dark in the middle of the Y direction of the beam spot on the fluorescent target, the eight-stage field current of the four-eight-pole composite magnet 1 is reduced until the brightness of the beam spot on the fluorescent target in the Y direction is evenly distributed, and the beam spot shape is changed from a circle to a rectangle.
Supplementary notes D:
The intersection current is calculated a first time in step six. The reason for calculating the intersection point current is that when the octupole field beam current is adjusted in the step six, the quadrupole field current adjusted in the front is changed, in order to solve the problem that the quadrupole field current is changed, the intersection point currents (namely the intersection point current obtained for the first time) need to be found, namely the current and octupole field gradients and the quadrupole field gradient reserved in the front are intersected with the magnetic field gradient curved surface of the three-dimensional sample database (namely the intersection of the plane and the curved surface is the first time), two corresponding current curves are obtained after the intersection, the intersection point of the two current curves is shown in the figure 2i, and the current value on the intersection point meets the requirement of the current octupole field gradient and also meets the requirement of the quadrupole field gradient simultaneously, so that the problem that the coupling relationship exists when the quadrupole composite iron is composited together is solved.
Step seven, if the homogenization change of the beam current is not obvious when the octupole field current of the tetraoctupole composite iron 1 is regulated, the quadrupole field gradient of the tetraoctupole composite iron 1 needs to be modified for phase shift matching, so that the Y-direction phase shift from the tetraoctupole composite iron 1 to a target is close to 180 degrees, namely, the intersection point current which simultaneously meets the quadrupole field gradient and the octupole field gradient of the tetraoctupole composite iron 1 is calculated according to the regulated quadrupole field gradient of the tetraoctupole composite iron 1 and the octupole field gradient reserved in the step six;
supplementary notes E:
The intersection current is calculated a second time in step seven. The first time of obtaining the intersection point current is when adjusting the octupole field of the quadrupole composite iron 1 to adjust the homogenization effect of the beam current in the Y direction, the second time of obtaining the intersection point current is because the homogenization change of the beam current is not obvious when adjusting the octupole field current of the quadrupole composite iron 1, and the quadrupole field gradient of the quadrupole composite iron 1 needs to be modified to carry out phase shift matching at the moment, because the quadrupole field gradient changes, the novel quadrupole field gradient and the octupole field gradient reserved in the step five are intersected with the magnetic field gradient curved surface of the three-dimensional sample database (the intersection of the plane and the curved surface is the second time), and two corresponding current curves are obtained after the intersection, the intersection point of the two current curves is shown in the figure 2i, and the current value on the intersection point meets the requirement of the current octupole field gradient at the present time, and also meets the requirement of the quadrupole field gradient, so that the problem of coupling relation exists when the quadrupole composite iron is composited together is solved.
The method comprises the following steps:
1) If the brightness of the middle and two sides of the Y direction of the beam spot on the fluorescent target is almost unchanged, the phase shift of the Y direction from the four-eight-pole composite magnet 1 to the target is larger than the 180 DEG difference, if the middle of the Y direction of the beam spot on the fluorescent target is changed from light to dark, the two sides are changed from dark to light or the middle is changed from dark to light, the two sides are changed from light to dark, the phase shift of the Y direction from the four-eight-pole composite magnet 1 to the target is close to 180 DEG, the brightness is more particles, and the darkness is less particles;
2) When the brightness change of the beam spot in the Y direction on the fluorescent target is not obvious, the difference between the beam Y phase shift and 180 degrees between the four-eight-pole compound magnet 1 and the target is proved to be larger, the current phase shift is smaller than 180 degrees, the quadrupole iron current in front of the four-eight-pole compound magnet 1 is reduced, or the quadrupole iron current of the four-eight-pole compound magnet 1 is increased, the method is observed again according to the method in 1) after the operation is finished, if the brightness change of the beam spot in the Y direction on the fluorescent target is obvious when the field current of the eight-pole compound magnet 1 is increased, the explanation is correct, if the brightness of the beam spot in the Y direction on the fluorescent target is almost unchanged, the current phase shift is larger than 180 degrees, the quadrupole iron current in front of the four-eight-pole compound magnet 1 is increased, or the quadrupole iron current of the four-eight-pole compound magnet 1 is reduced, the method in 1) is observed again after the operation is finished, until the brightness change of the beam spot in the Y direction on the fluorescent target is obvious when the field current of the eight-pole compound magnet 1 is increased, and the phase shift is close to 180 degrees.
Step eight, adjusting an octupole field of the tetraoctupole composite iron 2 to adjust the homogenization effect of the beam current in the X direction, and calculating to obtain intersection point current which simultaneously meets the quadrupole field gradient and the octupole field gradient of the tetraoctupole composite iron 2 according to the quadrupole field gradient of the tetraoctupole composite iron 2 recorded in the step five and the current octupole field gradient of the tetraoctupole composite iron 2, and reserving the octupole field gradient of the tetraoctupole composite iron 2 at the moment;
The method comprises the following steps:
The brightness of the beam spot on the fluorescent target in the X direction is uneven, if the brightness is shown as bright in the middle and dark at two sides in the X direction of the beam spot on the fluorescent target, the eight-stage field current of the four-eight-pole composite magnet 2 is increased until the brightness in the X direction of the beam spot on the fluorescent target is evenly distributed, the beam spot shape is changed into a square shape from a rectangular shape, and if the brightness is shown as bright at two sides and dark in the middle in the X direction of the beam spot on the fluorescent target, the eight-stage field current of the four-eight-pole composite magnet 2 is reduced until the brightness in the X direction of the beam spot on the fluorescent target is evenly distributed, and the beam spot shape is changed into a square shape from a rectangular shape.
Supplementary notes F:
The intersection current is calculated a third time in step eight. The third time is to obtain the difference between the intersecting point current and the previous second time, the previous second time is to adjust the octupole field of the quadrupole composite iron 1 when the intersecting point current is obtained, and the third time is to adjust the octupole field of the quadrupole composite iron 2;
step nine, if the homogenization change of the beam current is not obvious when the current of the quadripole composite iron 2 octupole field is regulated, the beam envelope of the X direction at the quadripole composite iron 2 needs to be increased, and the specific process is as follows:
1) If the brightness of the middle and two sides of the X direction of the beam spot on the fluorescent target is almost unchanged, the X direction beam envelope at the position of the four-eight-pole compound magnet 2 is smaller, if the middle of the X direction of the beam spot on the fluorescent target is darkened by light, the two sides are darkened by dark or the middle is darkened by dark, the two sides are darkened by light, the size of the X direction beam envelope at the position of the four-eight-pole compound magnet 2 is consistent with the homogenization requirement;
2) When the brightness change of the beam spot in the X direction on the fluorescent target is not obvious, the quadrupole iron current is increased, and whether the brightness change of the beam spot in the X direction on the fluorescent target is obvious or not is observed again according to the method in 1), if the brightness change of the beam spot is not obvious, the quadrupole iron current is continuously increased, and if the brightness change of the beam spot is obvious, the envelope size of the beam current in the X direction at the position of the quadrupolar compound magnet 2 meets the homogenization requirement, and the adjustment is completed.
Supplementary notes G:
in step nine, the intersection point current is not continuously obtained, because the phase shift of the beam current in the X direction from the quadrupolar ferromagnet 2 to the target is already close to 0 degree, the problem of increasing the envelope of the beam current in the X direction at the quadrupolar ferromagnet 2 can not be solved by a phase shift method, the quadrupolar iron current in front of the quadrupolar ferromagnet 1 needs to be increased, and as the quadrupolar iron current is increased, the envelope of the beam current in the X direction at the quadrupolar ferromagnet 2 is increased until the homogenization change of the beam current in the X direction on the target is obvious when the octupolar field current of the quadrupolar ferromagnet 2 is changed.
Example 1
As shown in fig. 14, the present invention designs an ultrashort linear beam homogenization transmission line. When the total length of the ultra-short linear beam homogenization transmission line is 6 meters, the initial layout positions of components capable of enabling the transmission line to obtain a good homogenization effect are sequentially 100mm for the fluorescent target 1, 900mm for the quadrupole magnet (Q0), 1300mm for the guide magnet, 1900mm for the tetraoctapole composite iron (Q1), 4200mm for the 3050mm Faraday cylinder, 5200mm for the fluorescent target 2, 5600mm for the double wire, and 6000mm for the terminal. Wherein the magnetic field component of the quadrupolar iron (Q0) is 2.9 (T/m), the quadrupolar magnetic field component of the quadrupolar iron (Q1) is 3.05 (T/m), the octupolar magnetic field component is 2.5e3 (T/m 3), the quadrupolar magnetic field component of the quadrupolar iron (Q2) is 0.45 (T/m), and the octupolar magnetic field component is 3.82e3 (T/m 3).
As shown in fig. 6e, for comparison before and after homogenization of the transmission line of the present invention, the left graph of fig. 6e is a sectional view of the beam in gaussian distribution before homogenization, that is, the beam of the fluorescent target 1 at the position of 100mm of the transmission line, and the right graph of fig. 6e is a sectional view of the beam after homogenization, that is, the beam of the fluorescent target 2 at the position of 5200mm of the transmission line. As can be seen from the figure, the distribution of particles on the beam cross section is dense in the middle and sparse in the periphery before homogenization, and the distribution of particles on the beam cross section is uniform in the middle and periphery after homogenization.
Example two
As shown in FIG. 15, the invention designs an ultra-short bend-conversion beam homogenization transmission line. When the total length of the ultra-short bent beam line is 6, the initial layout positions of components capable of enabling the line to obtain a good homogenization effect are sequentially 100mm for the fluorescent target 1, 1300mm for the quadrupole magnet (Q0), 1650mm for the guide magnet 1, 2100mm for the quadrupolar compound iron (Q1), 2700mm for the dipolar iron, 3850mm for the quadrupolar compound iron (Q2), 4250mm for the guide magnet 2, 4700mm for the Faraday cylinder, 5350mm for the fluorescent target 2, 5750mm for the twin wire, and 6000mm for the terminal.
Wherein the magnetic field component of the quadrupolar iron (Q0) is 6.8 (T/m), the quadrupolar magnetic field component of the quadrupolar iron (Q1) is 2.25 (T/m), the octupolar magnetic field component is 1e4 (T/m 3), the quadrupolar magnetic field component of the quadrupolar iron (Q2) is 0.6 (T/m), and the octupolar magnetic field component is 6.25e3 (T/m 3). The beam is deflected by 90 degrees, the incident angle and the emergent angle are 45 degrees, and the deflection radius is 0.55m.
As shown in fig. 7e, for comparison before and after homogenization of the transmission line of the present invention, the left graph of fig. 7e is a sectional view of the beam in gaussian distribution before homogenization, that is, the beam of the fluorescent target 1 at the position of 100mm of the transmission line, and the right graph of fig. 7e is a sectional view of the beam after homogenization, that is, the beam of the fluorescent target 2 at the position of 5350mm of the transmission line. As can be seen from the figure, the distribution of particles on the beam cross section is dense in the middle and sparse in the periphery before homogenization, and the distribution of particles on the beam cross section is uniform in the middle and periphery after homogenization.
Example III
As shown in FIG. 16, the invention designs an ultrashort symmetrical turning beam homogenization transmission line. When the total length of the ultra-short symmetrical bent-turn beam homogenization transmission line is 6.5 m, the initial layout positions of components capable of enabling the streamline to obtain a good homogenization effect are sequentially 100mm for the fluorescent target 1, 700mm for the quadrupole magnet (Q0), 1100mm for the guide magnet 1, 1600mm for the quadrupolar composite iron (Q1), 2200mm for the diode, 3500mm for the quadrupolar composite iron (Q2/Q3), 4200mm for the guide magnet 2/3, 4800mm for the Faraday cylinder 1/2, 5500mm for the fluorescent target 2/3, 6000mm for the twin wire 1/2, and 6500mm for the terminal 1/2.
Wherein the magnetic field component of the quadrupolar iron (Q0) is 6 (T/m), the quadrupolar magnetic field component of the quadrupolar iron (Q1) is 2.6 (T/m), the octupolar magnetic field component is 3.5e3 (T/m 3), the quadrupolar magnetic field component of the quadrupolar iron (Q2/Q3) is 0.55 (T/m), and the octupolar magnetic field component is 3e3 (T/m 3). The entrance edge angle 0, the exit edge angle 32 deg. of the dipoles and the beam turns 45 deg..
As shown in FIG. 8f, for comparison before and after homogenization of the transmission line of the present invention, the left view of FIG. 8f is a sectional view of the beam in Gaussian distribution before homogenization, that is, the beam of the fluorescent target 1 at the position of 100mm of the transmission line, and the right view of FIG. 8f is a sectional view of the beam after homogenization, that is, the beam of the fluorescent target 2/3 at the position of 5500mm of the transmission line. As can be seen from the figure, the distribution of particles on the beam cross section is dense in the middle and sparse in the periphery before homogenization, and the distribution of particles on the beam cross section is uniform in the middle and periphery after homogenization.
Example IV
As shown in FIG. 17, the invention designs an ultra-short straight line bent composite beam homogenization transmission line. When the total length of the ultra-short straight bent composite beam homogenization transmission line is 6 meters, the initial layout positions of components capable of enabling the streamline to obtain a good homogenization effect are sequentially 100mm for the fluorescent target 1, 700mm for the quadrupole magnet (Q0), 1150mm for the guide magnet 1, 1800mm for the tetraoctapole composite iron (Q1), 2600mm for the tetraoctapole composite iron (Q2), 3600mm for the diode, 4700mm for the tetraoctapole composite iron (Q3), 5200mm for the guide magnet 2, 5500mm for the Faraday cylinder 1, 5950mm for the fluorescent target 2, 6250mm for the double wire 1, and 6500mm for the terminal 1. The initial position of the Faraday cage 2 was 4450mm, the initial position of the fluorescent target 3 was 5150mm, the initial position of the double wire 2 was 5600mm, and the initial position of the terminal 2 was 6000mm.
Wherein the magnetic field component of the quadrupolar iron (Q0) is 6.2 (T/m), the quadrupolar magnetic field component of the quadrupolar iron (Q1) is 3.57/3.0 (T/m), the octupolar magnetic field component is 2.25e3/3.75e3 (T/m 3), the quadrupolar magnetic field component of the quadrupolar iron (Q2) is 3.5/0.75 (T/m), and the octupolar magnetic field component is 0/7.5e3 (T/m 3). The beam is deflected by 90 degrees, the incident and emergent angles are 45 degrees, the deflection radius is 0.5m, the quadrupole magnetic field component of the quadrupolar-octopole composite iron (Q3) is 1.0 (T/m), and the octopole magnetic field component is 5e 3(T/m3.
As shown in FIG. 9g, the composite curved beam homogenization transmission line is compared before and after homogenization, the left view of FIG. 9g is a beam screenshot of Gaussian distribution before homogenization, namely, the beam cross-section of the fluorescent target 1 at the position of 100mm of the transmission line, and the right view of FIG. 9g is a beam cross-section of the fluorescent target 2 at the position of 5950mm of the transmission line. As can be seen from the figure, the distribution of particles on the beam cross section is dense in the middle and sparse in the periphery before homogenization, and the distribution of particles on the beam cross section is uniform in the middle and periphery after homogenization.
As shown in fig. 9h, the homogenization of the composite linear beam homogenization transmission line is compared before and after homogenization, the left view in fig. 9h is a beam screenshot of gaussian distribution before homogenization, namely, a beam sectional view of the fluorescent target 1 at a position of 100mm of the transmission line, and the right view in fig. 9h is a beam sectional view after homogenization, namely, a beam sectional view of the fluorescent target 3 at a position of 5150mm of the transmission line. As can be seen from the figure, the distribution of particles on the beam cross section is dense in the middle and sparse in the periphery before homogenization, and the distribution of particles on the beam cross section is uniform in the middle and periphery after homogenization.
It should be emphasized that the above-described embodiments are merely illustrative of the invention, which is not limited thereto, and that modifications may be made by those skilled in the art, as desired, without creative contribution to the above-described embodiments, while remaining within the scope of the patent laws.

Claims (13)

1.一种基于四八极复合磁铁的超短束流均匀化传输线系统，其特征在于：该传输线系统包括四八极复合磁铁、四八极复合磁铁系统、超短直线型束流均匀化结构、超短弯转型束流均匀化结构、用于超短对称弯转型束流均匀化传输线的二极铁；1. An ultrashort beam homogenization transmission line system based on a four-octet composite magnet, characterized in that: the transmission line system includes a four-octet composite magnet, a four-octet composite magnet system, an ultrashort straight beam homogenization structure, an ultrashort curved beam homogenization structure, and a dipolar iron for ultrashort symmetrical curved beam homogenization transmission line. 还包括基于所述四八极复合磁铁、四八极复合磁铁系统、超短直线型束流均匀化结构的一种超短直线型束流均匀化传输线；It also includes an ultra-short straight beam homogenization transmission line based on the aforementioned four-eight-pole composite magnet, four-eight-pole composite magnet system, and ultra-short straight beam homogenization structure; 还包括基于所述四八极复合磁铁、四八极复合磁铁系统、超短弯转型束流均匀化结构的一种超短弯转型束流均匀化传输线；It also includes an ultra-short bend transition beam homogenization transmission line based on the aforementioned four-eight-pole composite magnet, four-eight-pole composite magnet system, and ultra-short bend transition beam homogenization structure. 还包括基于所述四八极复合磁铁、四八极复合磁铁系统、超短直线型束流均匀化结构、超短弯转型束流均匀化结构的一种超短直线弯转复合型束流均匀化传输线；It also includes an ultra-short straight-curved composite beam homogenization transmission line based on the aforementioned four-eight-pole composite magnet, four-eight-pole composite magnet system, ultra-short straight beam homogenization structure, and ultra-short curved beam homogenization structure. 还包括基于所述四八极复合磁铁、四八极复合磁铁系统、超短弯转型束流均匀化结构、以及用于超短对称弯转型束流均匀化传输线的二极铁的一种超短对称弯转型束流均匀化传输线；It also includes an ultra-short symmetrical bend beam homogenization transmission line based on the aforementioned four-octet composite magnet, four-octet composite magnet system, ultra-short bend beam homogenization structure, and a dipolar iron for ultra-short symmetrical bend beam homogenization transmission line. 所述四八极复合磁铁，一共有八个极头，每个极头在靠近大半径处沿着半径方向设有内外两层电流线圈，内层线圈为八极磁场励磁线圈，外层线圈四极磁场励磁线圈；该四八极复合磁铁布设在超短束流均匀化传输线上，用于和其前面的四极铁共同生成四八极复合铁A位置处的Y方向的大包络，以及四八极复合磁铁B和其前面的四八极复合铁A的四极铁共同生成四八极复合磁铁B位置处的X方向的大包络，从而将高斯分布的束流均匀化，且将四八极复合磁铁安装在束流传输线上，能够减少传输元件的个数，缩短传输线的长度；The four-eight-pole composite magnet has eight poles. Each pole has two layers of current coils along the radial direction near the large radius. The inner coil is an eight-pole magnetic field excitation coil, and the outer coil is a four-pole magnetic field excitation coil. The four-eight-pole composite magnet is arranged on the ultra-short beam homogenization transmission line. It is used to generate a large envelope in the Y direction at the position of the four-eight-pole composite magnet A together with the four-pole iron in front of it, and to generate a large envelope in the X direction at the position of the four-eight-pole composite magnet B together with the four-pole iron in front of it of the four-eight-pole composite magnet A. This homogenizes the Gaussian distributed beam. Furthermore, installing the four-eight-pole composite magnet on the beam transmission line can reduce the number of transmission elements and shorten the length of the transmission line. 所述四八极复合磁铁系统，包括复合磁铁电流控制装置、复合磁铁主电源以及四八极复合磁铁；该复合磁铁电流控制装置用于控制复合磁铁主电源对四八极复合磁铁的四极场线圈电流输出和八极场线圈电流输出；该四八极复合磁铁用于同时产生主导四极磁场、八极磁场，从而仅安装一个传输元件就能同时实现四极铁和八极铁的作用；The four-eight-pole composite magnet system includes a composite magnet current control device, a composite magnet main power supply, and a four-eight-pole composite magnet. The composite magnet current control device is used to control the current output of the four-pole field coil and the eight-pole field coil of the four-eight-pole composite magnet from the composite magnet main power supply. The four-eight-pole composite magnet is used to simultaneously generate a dominant four-pole magnetic field and an eight-pole magnetic field, so that the functions of a four-pole iron and an eight-pole iron can be realized simultaneously by installing only one transmission element. 所述超短直线型束流均匀化结构，在传输线上使用两块四八极复合磁铁，该两块四八极复合磁铁分别同时产生四极磁场和八极磁场，从而仅安装一个传输元件就能同时实现四极铁和八极铁的作用；The ultra-short linear beam homogenization structure uses two quadrupole-octupole composite magnets on the transmission line. These two quadrupole-octupole composite magnets generate quadrupole magnetic fields and octupole magnetic fields simultaneously, so that only one transmission element is installed to achieve the functions of quadrupole iron and octupole iron at the same time. 所述超短弯转型束流均匀化结构，通过在传输线上使用一块二极铁和多块四八极复合铁，实现弯转型束流均匀化子结构和对称弯转型束流均匀化子结构；该弯转型束流均匀化子结构用于实现弯转型束流均匀化传输线；该对称弯转型束流均匀化子结构用于实现超短对称弯转型束流均匀化传输线；The ultra-short bend-type beam homogenization structure utilizes a diode iron and multiple quadrupole composite irons on the transmission line to realize a bend-type beam homogenization substructure and a symmetrical bend-type beam homogenization substructure. The bend-type beam homogenization substructure is used to realize a bend-type beam homogenization transmission line, and the symmetrical bend-type beam homogenization substructure is used to realize an ultra-short symmetrical bend-type beam homogenization transmission line. 所述用于超短对称弯转型束流均匀化传输线的二极铁，该二极铁为共用二极铁，该共用二极铁为出口边带有上下对称边缘角的二极铁，具体为：其束流入口边为直线，其束流出口边为一对上下对称的斜线，该上下对称斜线的倾斜方向为束流在出口边各自弯转的方向；该上下对称的斜线与束流弯转轨道的圆心到束流在二极铁出口处的连线构成二极铁出口边缘角；通过优化设计二极铁的边缘角大小，利用二极铁边缘场聚焦效果，并配合二极铁两边的四八极复合铁在Y方向的包络和X方向的包络，从而获得符合均匀化需求的理想相移；The diode used for the ultra-short symmetrical bending beam homogenization transmission line is a shared diode with symmetrical edge angles at the exit edge. Specifically, its beam inlet edge is a straight line, and its beam outlet edge is a pair of symmetrical diagonal lines. The inclination direction of these symmetrical diagonal lines is the direction in which the beam bends at the exit edge. The line connecting the center of the beam bending trajectory to the beam at the diode outlet edge forms the diode outlet edge angle. By optimizing the size of the diode edge angle, utilizing the edge field focusing effect of the diode, and cooperating with the envelopes of the four-eight-pole composite iron on both sides of the diode in the Y and X directions, an ideal phase shift that meets the homogenization requirements can be obtained. 所述一种超短直线型束流均匀化传输线,该传输线为包含二块四八极复合铁的直线型束流均匀化传输线；该直线型束流均匀化传输线沿束流方向依次设有：加速器引出口、束流匹配机构、四八极复合铁A、四八极复合铁B、束流均匀化效果观测机构、终端；The ultrashort linear beam homogenization transmission line is a linear beam homogenization transmission line containing two quadrupole-octupole composite irons. The linear beam homogenization transmission line is provided with the following components along the beam direction: accelerator outlet, beam matching mechanism, quadrupole-octupole composite iron A, quadrupole-octupole composite iron B, beam homogenization effect observation mechanism, and terminal. 所述一种超短弯转型束流均匀化传输线，该传输线为包含二块四八极复合铁和一块二极铁的超短弯转型束流均匀化传输线；该超短弯转型束流均匀化传输线为沿束流方向布设的超短弯转型束流均匀化传输线A，或沿束流方向布设的超短弯转型束流均匀化传输线B：该超短弯转型束流均匀化传输线A沿着束流引出方向依次设有：加速器引出口、束流匹配机构、四八极复合铁A、二极铁、四八极复合铁B、束流匹配和均匀化效果观测机构A、终端A；该超短弯转型束流均匀化传输线B沿着束流引出方向依次设有：加速器引出口、束流匹配机构、四八极复合铁A、二极铁、四八极复合铁C、束流匹配和均匀化效果观测机构B、终端B；The ultra-short bend transition beam homogenization transmission line comprises two quadrupole-octupole composite iron pieces and one dipole iron piece. This ultra-short bend transition beam homogenization transmission line can be either Ultra-short bend transition beam homogenization transmission line A or Ultra-short bend transition beam homogenization transmission line B, arranged along the beam direction. Ultra-short bend transition beam homogenization transmission line A, along the beam exit direction, sequentially includes: an accelerator outlet, a beam matching mechanism, quadrupole-octupole composite iron A, a dipole iron piece, quadrupole-octupole composite iron B, a beam matching and homogenization effect observation mechanism A, and a terminal A. Ultra-short bend transition beam homogenization transmission line B, along the beam exit direction, sequentially includes: an accelerator outlet, a beam matching mechanism, quadrupole-octupole composite iron A, a dipole iron piece, quadrupole-octupole composite iron C, a beam matching and homogenization effect observation mechanism B, and a terminal B. 所述一种超短对称弯转型束流均匀化传输线，为分别包含二块四八极复合铁和一块共用二极铁的对称弯转型束流均匀化传输线；该分别包含二块四八极复合铁和一块共用二极铁的对称弯转型束流均匀化传输线，由一条共用束流线和二条分支束流线组成；The aforementioned ultrashort symmetrical bend beam homogenization transmission line is a symmetrical bend beam homogenization transmission line comprising two quadrature octet composite irons and one common diode iron; the symmetrical bend beam homogenization transmission line comprising two quadrature octet composite irons and one common diode iron consists of one common beamline and two branch beamlines. 所述一种超短直线弯转复合型束流均匀化传输线，由一条包含二块四八极复合铁的直线型束流均匀化传输线和一条包含二块四八极复合铁和一块二极铁的弯转型束流均匀化传输线组成；该直线型束流均匀化传输线和弯转型束流均匀化传输线由一条共用传输线和二条分支传输线组成；The aforementioned ultra-short straight-line-bending composite beam homogenization transmission line consists of a straight beam homogenization transmission line containing two quadrature-octet composite iron pieces and a bending beam homogenization transmission line containing two quadrature-octet composite iron pieces and one dipolar iron piece; the straight beam homogenization transmission line and the bending beam homogenization transmission line consist of a common transmission line and two branch transmission lines. 所述超短弯转型束流均匀化结构、超短弯转型束流均匀化传输线、一种超短对称弯转型束流均匀化传输线、一种超短直线弯转复合型束流均匀化传输线，利用四八极复合铁A和二极铁的共同的聚焦效果叠加生成四八极复合铁B或四八极复合铁C附近处的Y方向的束流腰部；利用二极铁和四八极复合铁B或二极铁和四八极复合铁C的四极场叠加生成靶上的X方向的包络尺寸，使得X方向和Y方向的包络尺寸一致；The ultra-short bend-type beam homogenization structure, ultra-short bend-type beam homogenization transmission line, ultra-short symmetrical bend-type beam homogenization transmission line, and ultra-short straight-line bend-type composite beam homogenization transmission line utilize the combined focusing effect of octet-pole composite iron A and dipole iron to generate a beam waist in the Y direction near octet-pole composite iron B or octet-pole composite iron C; and utilize the quadrupole field superposition of dipole iron and octet-pole composite iron B or dipole iron and octet-pole composite iron C to generate the envelope size in the X direction on the target, so that the envelope sizes in the X and Y directions are consistent. 所述超短直线型束流均匀化结构、超短弯转型束流均匀化结构、一种超短直线型束流均匀化传输线、一种超短弯转型束流均匀化传输线、一种超短直线弯转复合型束流均匀化传输线、一种超短对称弯转型束流均匀化传输线，在第一块四八极复合磁铁处，Y方向或X方向束流包络函数达到较大值，在第二块四八极复合磁铁处，X方向或Y方向束流包络函数达到较大值；粒子在两块四八极复合磁铁与靶之间的相位移动分别接近于180度的整数倍；两个八极磁场之间的传输矩阵接近于单位矩阵。The ultrashort linear beam homogenization structure, ultrashort curved beam homogenization structure, an ultrashort linear beam homogenization transmission line, an ultrashort curved beam homogenization transmission line, an ultrashort linear-curved composite beam homogenization transmission line, and an ultrashort symmetrical curved beam homogenization transmission line all exhibit the following characteristics: At the first quadruple-octagonal composite magnet, the beam envelope function in the Y or X direction reaches a large value; at the second quadruple-octagonal composite magnet, the beam envelope function in the X or Y direction reaches a large value; the phase shift of the particle between the two quadruple-octagonal composite magnets and the target... They are all close to integer multiples of 180 degrees; the transmission matrix between the two octagonal magnetic fields is close to the identity matrix. 2.根据权利要求1所述的一种基于四八极复合磁铁的超短束流均匀化传输线系统，其特征在于：2. The ultrashort beam homogenization transmission line system based on a four-octet composite magnet according to claim 1, characterized in that: 该超短弯转型束流均匀化结构，沿着束流方向依次布设有：四八极复合铁A、二极铁、四八极复合铁B和/或四八极复合铁C；该二极铁用于将束流线的束流方向由直线型变为弯转型；该四八极复合铁A、四八极复合铁B和/或四八极复合铁C用于分别同时产生四极磁场和八极磁场，从而仅安装一个传输元件就能同时实现四极铁和八极铁的作用；该弯转型束流均匀化子结构，在二极铁的上游设有四八极复合铁A，在二极铁的下游设有四八极复合铁B或四八极复合铁C；该对称弯转型束流均匀化子结构，包括对称第一条弯转型束流均匀化结构和对称第二条弯转型束流均匀化结构；该对称第一条弯转型束流均匀化结构，在二极铁的上游设有四八极复合铁A、在二极铁的下游布设四八极复合铁B；该对称第二条弯转型束流均匀化结构，在二极铁的上游设有四八极复合铁A、在二极铁的下游布设四八极复合铁C；该对称第一条弯转型束流均匀化结构和对称第二条弯转型束流均匀化结构分时工作；基于该对称弯转型束流均匀化子结构的对称弯转型束流均匀化传输线上的二极铁，为超短对称弯转型束流均匀化传输线上的共用二极铁，该共用二极铁为出口边带有上下对称边缘角的二极铁，具体为：其束流入口边为直线，其束流出口边为一对上下对称的斜线，该上下对称斜线的倾斜方向为束流在出口边各自弯转的方向；该上下对称的斜线与束流弯转轨道的圆心到束流在二极铁出口处的连线构成二极铁出口边缘角；通过改变二极铁出口边缘角的大小调整二极铁的边缘场聚焦效果，并配合二极铁两边的四八极复合铁在Y方向的包络和X方向的包络，从而获得符合均匀化需求的理想相移；This ultra-short bendable beam homogenization structure comprises, sequentially along the beam direction, four-octagonal composite iron A, a dipole iron, four-octagonal composite iron B, and/or four-octagonal composite iron C. The dipole iron is used to change the beam direction from a straight line to a bend. The four-octagonal composite iron A, B, and/or C are used to simultaneously generate quadrupole and octagonal magnetic fields, respectively, thus enabling the simultaneous function of both quadrupole and octagonal irons with only one transmission element. This bendable beam homogenization substructure… The structure comprises a 4x8 pole composite iron A upstream of the dipole and a 4x8 pole composite iron B or C downstream of the dipole; this symmetrical bending-type beam homogenization substructure includes a symmetrical first bending-type beam homogenization structure and a symmetrical second bending-type beam homogenization structure; the symmetrical first bending-type beam homogenization structure has a 4x8 pole composite iron A upstream of the dipole and a 4x8 pole composite iron B downstream of the dipole; the symmetrical second bending-type beam homogenization structure has a 4x8 pole composite iron A upstream of the dipole and a 4x8 pole composite iron B downstream of the dipole; Upstream of the iron is a 4-octet composite iron A, and downstream of the diode is a 4-octet composite iron C. The symmetrical first bending beam homogenization structure and the symmetrical second bending beam homogenization structure operate in a time-division manner. The diodes on the symmetrical bending beam homogenization transmission line based on the symmetrical bending beam homogenization substructure are shared diodes on the ultra-short symmetrical bending beam homogenization transmission line. These shared diodes have symmetrical edge angles at their exit edges. Specifically, their beam inlet edge is a straight line, and their beam outlet edge is a pair of symmetrical oblique lines. The inclination direction of these symmetrical oblique lines is the direction in which the beam bends at the exit edge. The line connecting the center of the beam bending track to the beam at the diode outlet forms the diode outlet edge angle. By changing the size of the diode outlet edge angle, the edge field focusing effect of the diode is adjusted, and in conjunction with the envelopes of the 4-octet composite irons on both sides of the diode in the Y and X directions, an ideal phase shift that meets the homogenization requirements is obtained. 该一种超短直线弯转复合型束流均匀化传输线的共用传输线沿束流方向依次设有：加速器引出口、束流匹配机构、四八极复合铁A、四八极复合铁B；其中，四八极复合铁B在应用于弯转型分支传输线时只有四极场没有八极场；该二条分支传输线为直线型分支传输线和弯转型分支传输线；该直线型分支传输线设有束流均匀化效果观测机构以及终端；该弯转型分支传输线设有二极铁、四八极复合磁铁C、束流匹配和均匀化效果观测机构以及终端；该共用传输线和该直线型分支传输线组成复合直线型束流均匀化传输线；该共用传输线和该弯转型分支传输线组成复合弯转型束流均匀化传输线；该复合直线型束流均匀化传输线和复合弯转型束流均匀化传输线分时工作；该复合直线型束流均匀化传输线的四八极复合铁A、四八极复合铁B和该复合弯转型束流均匀化传输线的四八极复合铁A、四八极复合铁C分别同时产生四极磁场和八极磁场，从而仅安装一个传输元件就能同时实现四极铁和八极铁的作用；This ultra-short, straight-line, curved-type composite beam homogenization transmission line has the following components along the beam direction: an accelerator outlet, a beam matching mechanism, a four-eight-pole composite iron A, and a four-eight-pole composite iron B; wherein, when the four-eight-pole composite iron B is applied to the curved-type branch transmission line, it only has a four-pole field and not an eight-pole field; the two branch transmission lines are a straight-line branch transmission line and a curved-type branch transmission line; the straight-line branch transmission line has a beam homogenization effect observation mechanism and a terminal; the curved-type branch transmission line has a two-pole iron, a four-eight-pole composite magnet C, a beam matching and homogenization effect observation mechanism, and a terminal; the common transmission line is equipped with: an accelerator outlet, a beam matching mechanism, a four-eight-pole composite magnet A, a beam matching and homogenization effect observation mechanism, and a terminal; A composite linear beam homogenization transmission line is formed by combining a transmission line and the linear branch transmission line; a composite curved beam homogenization transmission line is formed by combining a common transmission line and the curved branch transmission line; the composite linear beam homogenization transmission line and the composite curved beam homogenization transmission line operate in a time-division manner; the four-eight-pole composite iron A and four-eight-pole composite iron B of the composite linear beam homogenization transmission line and the four-eight-pole composite iron A and four-eight-pole composite iron C of the composite curved beam homogenization transmission line simultaneously generate a quadrupole magnetic field and an octupole magnetic field, respectively, so that the functions of a quadrupole iron and an octupole iron can be realized simultaneously by installing only one transmission element; 该一种超短对称弯转型束流均匀化传输线的共用束流线沿束流方向依次设有：加速器引出口、束流匹配机构、四八极复合铁A、二极铁；该二条分支束流线为第一分支束流线、第二分支束流线；该第一分支束流线依次设有四八极复合铁B、束流匹配和均匀化效果观测机构A、终端A；该第二分支束流线依次设有四八极复合铁C、束流匹配和均匀化效果观测机构B、终端B；该共用束流线和所述第一分支束流线组成第一弯转型束流均匀化传输线；该共用束流线和所述第二分支束流线组成第二弯转型束流均匀化传输线；该第一弯转型束流均匀化传输线和该第二弯转型束流均匀化传输线分时工作；该第一弯转型束流均匀化传输线和第二弯转型束流均匀化传输线的四八极复合铁A、四八极复合铁B、以及四八极复合铁C分别同时产生四极磁场和八极磁场，从而仅安装一个传输元件就能同时实现四极铁和八极铁的作用；所述共用二极铁为满足对称弯转型束流均匀化的二极铁，该二极铁在对称弯转的束流的入口边为上下对称的直边，在对称弯转的束流的出口边为上下对称的斜边，该对称斜边的倾斜方向为束流弯转的方向；该上下对称的斜线与束流弯转轨道的圆心到束流在二极铁出口处的连线构成二极铁出口边缘角；通过改变二极铁出口边缘角的大小调整二极铁的边缘场聚焦效果，并配合二极铁两边的四八极复合铁在Y方向的包络和X方向的包络，从而获得符合均匀化需求的理想相移。The common beamline of this ultra-short symmetrical bend-type beam homogenization transmission line is arranged along the beam direction as follows: an accelerator outlet, a beam matching mechanism, a quad-octet composite iron A, and a diode; the two branch beamlines are a first branch beamline and a second branch beamline; the first branch beamline is arranged with a quad-octet composite iron B, a beam matching and homogenization effect observation mechanism A, and a terminal A; the second branch beamline is arranged with a quad-octet composite iron C, a beam matching and homogenization effect observation mechanism B, and a terminal B; the common beamline and the first branch beamline form a first bend-type beam homogenization transmission line; the common beamline and the second branch beamline form a second bend-type beam homogenization transmission line; the first bend-type beam homogenization transmission line and the second bend-type beam homogenization transmission line operate in a time-division multiplexing manner; the first bend-type beam homogenization transmission line and the second bend-type beam homogenization transmission line... The four-eight-pole composite iron A, four-eight-pole composite iron B, and four-eight-pole composite iron C of the homogenization transmission line simultaneously generate a quadrupole magnetic field and an octupole magnetic field, respectively, so that only one transmission element is needed to achieve the functions of both quadrupole and octupole irons. The shared dipole iron is a dipole iron that satisfies the homogenization of the symmetrically bent beam. The dipole iron has a vertically symmetrical straight edge at the entrance side of the symmetrically bent beam and a vertically symmetrical inclined edge at the exit side of the symmetrically bent beam. The inclination direction of the symmetrical inclined edge is the direction of beam bending. The vertically symmetrical inclined line and the line connecting the center of the beam bending track to the beam at the exit of the dipole iron form the dipole iron exit edge angle. By changing the size of the dipole iron exit edge angle, the edge field focusing effect of the dipole iron is adjusted, and in conjunction with the envelopes of the four-eight-pole composite irons on both sides of the dipole iron in the Y direction and the X direction, an ideal phase shift that meets the homogenization requirements is obtained. 3.根据权利要求1所述的一种基于四八极复合磁铁的超短束流均匀化传输线系统，其特征在于：该四八极复合磁铁的内层的八极磁场励磁线圈，其相邻两个极头电流方向相反，即将八极场线圈分为1、3、5、7极头与2、4、6、8极头两组，二者的励磁电流大小相等，但电流方向相反，由此产生八极磁场；所述外层的四极磁场励磁线圈，其相邻两个极头上的线圈为一组，分为四组，即分别为1、2极头，3、4极头，5、6极头，7、8极头；其中，1、2极头与对称布设的5、6极头，这两组四极磁场线圈的励磁电流大小与方向一致，3、4极头与对称布设的7、8极头，这两组线圈的励磁电流大小与方向一致，1、2极头与3、4极头线圈的电流方向相反，5、6极头与7、8极头线圈的方向相反，由此产生了四极磁场。3. The ultrashort beam homogenization transmission line system based on a four-octet composite magnet according to claim 1, characterized in that: the inner layer of the four-octet composite magnet has an octet magnetic field excitation coil with adjacent poles having opposite current directions, that is, the octet field coil is divided into two groups: poles 1, 3, 5, 7 and poles 2, 4, 6, 8, with equal excitation current magnitudes but opposite current directions, thereby generating an octet magnetic field; the outer layer of the four-octet magnetic field excitation coil has coils on adjacent poles... The system is divided into four groups: poles 1 and 2, poles 3 and 4, poles 5 and 6, and poles 7 and 8. The excitation current of the coils in the groups of poles 1 and 2 and the symmetrically arranged poles 5 and 6 is in the same direction and magnitude. The excitation current of the coils in the groups of poles 3 and 4 and the symmetrically arranged poles 7 and 8 is in the same direction and magnitude. The current direction of the coils in the groups of poles 1 and 2 is opposite to that of the coils in the groups of poles 3 and 4. The current direction of the coils in the groups of poles 5 and 6 is opposite to that of the coils in the groups of poles 7 and 8. This generates a quadrupole magnetic field. 4.根据权利要求1所述的一种基于四八极复合磁铁的超短束流均匀化传输线系统，其特征在于：该四八极复合磁铁系统的复合磁铁电流控制装置包括：建立线圈电流二维采样点模块、实验测量初步建立磁场梯度三维曲面样本库模块、使用插值细化磁场梯度三维曲面样本库模块、输入场梯度求解对应场梯度电流曲线模块、求解四/八极场梯度电流曲线交点模块、输出四极/八极线圈电流模块；4. The ultrashort beam homogenization transmission line system based on a four-eight-pole composite magnet according to claim 1, characterized in that: the composite magnet current control device of the four-eight-pole composite magnet system includes: a module for establishing two-dimensional sampling points of coil current, a module for experimentally measuring and initially establishing a three-dimensional surface sample library of magnetic field gradient, a module for refining the three-dimensional surface sample library of magnetic field gradient using interpolation, a module for inputting field gradient and solving the corresponding field gradient current curve, a module for solving the intersection point of four/eight-pole field gradient current curves, and a module for outputting four/eight-pole coil current; 所述建立线圈电流二维采样点模块用于建立四极铁和八极铁的线圈电流二维数据对照表；The module for establishing two-dimensional sampling points for coil current is used to establish a two-dimensional data comparison table of coil current for quadrupole and octupole iron. 所述实验测量初步建立磁场梯度三维曲面样本库模块，是使用线圈电流二维数据对照表的电流值来对复合铁进行磁场实验测量，从而得到与二维电流数据对照表一一对应的四、八极磁场梯度测量值，从而得到磁场梯度的三维曲面样本数据库；上述磁场梯度的三维曲面样本数据库包括四极场磁场梯度三维曲面样本数据库，以及八极场磁场梯度三维曲面样本数据库；The experimental measurement initially establishes a three-dimensional surface sample library module for magnetic field gradients. This module uses the current values from a two-dimensional data lookup table of coil currents to perform magnetic field experimental measurements on composite iron, thereby obtaining four-pole and octole magnetic field gradient measurement values that correspond one-to-one with the two-dimensional current data lookup table, thus obtaining a three-dimensional surface sample database of magnetic field gradients. The aforementioned three-dimensional surface sample database of magnetic field gradients includes a four-pole field magnetic field gradient three-dimensional surface sample database and an octole field magnetic field gradient three-dimensional surface sample database. 所述使用插值细化磁场梯度三维曲面样本库模块，用于使用三次样条函数，对该四极场磁场梯度三维曲面样本数据库，以及八极场磁场梯度三维曲面样本数据库进行二维插值，加密网格点密度；The module for refining the magnetic field gradient three-dimensional surface sample library using interpolation is used to perform two-dimensional interpolation on the quadrupole magnetic field gradient three-dimensional surface sample database and the octupole magnetic field gradient three-dimensional surface sample database using cubic spline functions, thereby increasing the density of grid points. 所述输入场梯度求解对应场梯度电流曲线模块，用于将输入的四极场梯度和八极场梯度与三维样本数据库的磁场梯度曲面相交，相交后得到二条对应的电流曲线；具体为：选取四极场磁场梯度平面，该平面与四极场磁场梯度三维曲面样本数据库的曲面相交，得到满足该四极场梯度的电流曲线；选取八极场磁场梯度平面，该平面与八极场磁场梯度三维曲面样本数据库的曲面相交，得到满足该八极场梯度的电流曲线；The module for solving the input field gradient corresponding to the current curve is used to intersect the input quadrupole field gradient and octupole field gradient with the magnetic field gradient surface of the three-dimensional sample database, and obtain two corresponding current curves after the intersection; specifically: a quadrupole field magnetic field gradient plane is selected, and this plane intersects with the surface of the quadrupole field magnetic field gradient three-dimensional surface sample database to obtain the current curve that satisfies the quadrupole field gradient; an octupole field magnetic field gradient plane is selected, and this plane intersects with the surface of the octupole field magnetic field gradient three-dimensional surface sample database to obtain the current curve that satisfies the octupole field gradient. 所述求解四/八极场梯度电流曲线交点模块，用于获得满足四极场梯度的电流曲线和满足该八极场梯度的电流曲线的相交点，并用该相交点作为复合铁励磁电流的解；The module for solving the intersection point of the four/octet field gradient current curves is used to obtain the intersection point of the current curve that satisfies the four-pole field gradient and the current curve that satisfies the octet field gradient, and uses the intersection point as the solution of the composite iron excitation current. 所述输出四极/八极线圈电流模块，根据复合铁励磁电流的求解，向四八极复合磁铁输出四极场线圈电流和八极场线圈电流。The output four-pole/eight-pole coil current module outputs four-pole field coil current and eight-pole field coil current to the four-eight-pole composite magnet based on the solution of the composite iron excitation current. 5.根据权利要求1所述的一种基于四八极复合磁铁的超短束流均匀化传输线系统，其特征在于：所述超短直线型束流均匀化结构、超短弯转型束流均匀化结构、一种超短直线型束流均匀化传输线、一种超短弯转型束流均匀化传输线、一种超短直线弯转复合型束流均匀化传输线、一种超短对称弯转型束流均匀化传输线的粒子在两块四八极复合磁铁与靶之间的相位移动分别接近于180度的整数倍，是指接近但不等于180度的整数倍：设为与180度的余数，取值一般小于±15度。5. The ultrashort beam homogenization transmission line system based on a quad-octet composite magnet according to claim 1, characterized in that: the phase shift of particles in the ultrashort straight beam homogenization structure, ultrashort curved beam homogenization structure, ultrashort straight beam homogenization transmission line, ultrashort curved beam homogenization transmission line, ultrashort straight-curved composite beam homogenization transmission line, and ultrashort symmetrical curved beam homogenization transmission line between the two quad-octet composite magnets and the target. "Approaching multiples of 180 degrees" means approaching but not equal to multiples of 180 degrees: Let... for The remainder after 180 degrees, The value is generally less than ±15 degrees. 6.根据权利要求1所述的一种基于四八极复合磁铁的超短束流均匀化传输线系统，其特征在于：所述超短直线型束流均匀化结构、超短弯转型束流均匀化结构、一种超短直线型束流均匀化传输线、一种超短弯转型束流均匀化传输线、一种超短直线弯转复合型束流均匀化传输线、一种超短对称弯转型束流均匀化传输线的两个八极磁场之间的传输矩阵接近于单位矩阵，即前后两个四八极复合磁铁之间的相位移动控制在30度范围内，该30度范围能够极大的避免两块八极磁铁耦合造成的高阶非线性效应，且能够得到较好的均匀化效果。6. The ultrashort beam homogenization transmission line system based on a four-octet composite magnet according to claim 1, characterized in that: the transmission matrix between the two octet magnetic fields of the ultrashort straight beam homogenization structure, the ultrashort curved beam homogenization structure, the ultrashort straight beam homogenization transmission line, the ultrashort curved beam homogenization transmission line, the ultrashort straight-curved composite beam homogenization transmission line, and the ultrashort symmetrical curved beam homogenization transmission line is close to a unit matrix, that is, the phase shift between the two four-octet composite magnets is controlled within a range of 30 degrees. This 30-degree range can greatly avoid the high-order nonlinear effects caused by the coupling of the two octet magnets and can obtain a better homogenization effect. 7.根据权利要求1所述的一种基于四八极复合磁铁的超短束流均匀化传输线系统，其特征在于：所述超短直线型束流均匀化结构、超短弯转型束流均匀化结构、一种超短直线型束流均匀化传输线、一种超短弯转型束流均匀化传输线、一种超短直线弯转复合型束流均匀化传输线、一种超短对称弯转型束流均匀化传输线的第一块四八极复合磁铁、第二块四八极复合磁铁处的磁铁强度k的表达式为：7. The ultrashort beam homogenization transmission line system based on a four-octet composite magnet according to claim 1, characterized in that: the magnetic strength k at the first four-octet composite magnet and the second four-octet composite magnet of the ultrashort straight beam homogenization structure, the ultrashort curved beam homogenization structure, the ultrashort straight beam homogenization transmission line, the ultrashort curved beam homogenization transmission line, the ultrashort straight-curved composite beam homogenization transmission line, and the ultrashort symmetrical curved beam homogenization transmission line is expressed as: 设：输运线起点记为0，第一块四八极磁铁位置记为1，第二块四八极磁铁位置记为2，终点处位置也就是靶的位置记为3；上述公式(1)的ux02表示粒子在位置0和2之间x方向的相移，ux23表示粒子在位置2和3之间x方向的相移；βx2表示在位置2处x方向的包络函数；上述公式(2)的uy01表示粒子在0和1之间y方向的相移；uy13表示粒子在1和3之间y方向的相移；βy1表示在位置1处y方向的包络函数。Let: the starting point of the transport line be 0, the position of the first quadrupole magnet be 1, the position of the second quadrupole magnet be 2, and the position of the endpoint, which is the position of the target, be 3; in the above formula (1), ux02 represents the phase shift of the particle in the x direction between positions 0 and 2, ux23 represents the phase shift of the particle in the x direction between positions 2 and 3; βx2 represents the envelope function in the x direction at position 2; in the above formula (2), uy01 represents the phase shift of the particle in the y direction between 0 and 1; uy13 represents the phase shift of the particle in the y direction between 1 and 3; βy1 represents the envelope function in the y direction at position 1. 8.根据权利要求2所述的一种基于四八极复合磁铁的超短束流均匀化传输线系统，其特征在于：当超短弯转型束流均匀化结构使用弯转型束流均匀化子结构或对称第一条弯转型束流均匀化结构时，在四八极复合铁A处，Y方向或X方向束流包络函数达到较大值，在四八极复合铁B处，X方向或Y方向束流包络函数达到较大值；粒子在四八极复合铁A和四八极复合铁B与靶之间的相位移动分别接近于180度的整数倍；该两个八极磁场之间的传输矩阵接近于单位矩阵；当使用弯转型束流均匀化子结构或对称第二条弯转型束流均匀化结构时，在四八极复合铁A处，Y方向或X方向束流包络函数达到较大值，在四八极复合铁C处，X方向或Y方向束流包络函数达到较大值；粒子在四八极复合铁A和四八极复合铁C与靶之间的相位移动分别接近于180度的整数倍；该两个八极磁场之间的传输矩阵接近于单位矩阵。8. A transmission line system for ultrashort beam homogenization based on a quadrature-octet composite magnet according to claim 2, characterized in that: when the ultrashort bending beam homogenization structure uses a bending beam homogenization substructure or a symmetrical first bending beam homogenization structure, the beam envelope function in the Y or X direction reaches a large value at quadrature-octet composite magnet A, and the beam envelope function in the X or Y direction reaches a large value at quadrature-octet composite magnet B; the phase shift of the particle between quadrature-octet composite magnet A and quadrature-octet composite magnet B and the target. These values are close to integer multiples of 180 degrees; the transmission matrix between the two octagonal magnetic fields is close to an identity matrix; when using a bending-type beam homogenization substructure or a symmetrical second bending-type beam homogenization structure, the beam envelope function in the Y or X direction reaches a large value at the four-octagonal composite iron A, and the beam envelope function in the X or Y direction reaches a large value at the four-octagonal composite iron C; the phase shift of the particle between the four-octagonal composite iron A and C and the target. They are each close to an integer multiple of 180 degrees; the transmission matrix between the two octagonal magnetic fields is close to an identity matrix. 9.根据权利要求1所述的一种基于四八极复合磁铁的超短束流均匀化传输线系统，其特征在于：该超短对称弯转型束流均匀化传输线由一条共用传输线和二条分支传输线组成；该共用传输线沿束流方向依次设有：加速器引出口、束流匹配机构、四八极复合铁A、二极铁；该共用传输线和第一分支传输线的四八极复合铁B、束流匹配和均匀化效果观测机构A、终端A组成第一弯转型束流均匀化传输线；该共用传输线和第二分支传输线的四八极复合铁C、束流匹配和均匀化效果观测机构B、终端B组成第二弯转型束流均匀化传输线；该第一弯转型束流均匀化传输线和该第二弯转型束流均匀化传输线分时工作；9. A system for an ultrashort beam homogenization transmission line based on a quad-octet composite magnet according to claim 1, characterized in that: the ultrashort symmetrical curved beam homogenization transmission line consists of a common transmission line and two branch transmission lines; the common transmission line is provided with, in sequence along the beam direction: an accelerator outlet, a beam matching mechanism, a quad-octet composite magnet A, and a diode; the common transmission line and the quad-octet composite magnet B, the beam matching and homogenization effect observation mechanism A, and the terminal A of the first branch transmission line constitute a first curved beam homogenization transmission line; the common transmission line and the quad-octet composite magnet C, the beam matching and homogenization effect observation mechanism B, and the terminal B of the second branch transmission line constitute a second curved beam homogenization transmission line; the first curved beam homogenization transmission line and the second curved beam homogenization transmission line operate in a time-division multiplexing manner; 所述一种超短对称弯转型束流均匀化传输线，由一条共用传输线和二条分支传输线组成；该共用传输线沿束流方向依次设有：加速器引出口、束流匹配机构、四八极复合铁A、二极铁；该共用传输线和第一分支传输线的四八极复合铁B、束流匹配和均匀化效果观测机构A、终端A组成第一弯转型束流均匀化传输线；该共用传输线和第二分支传输线的四八极复合铁C、束流匹配和均匀化效果观测机构B、终端B组成第二弯转型束流均匀化传输线；该第一弯转型束流均匀化传输线和该第二弯转型束流均匀化传输线分时工作；该共用二极铁为出口边带有上下对称边缘角的二极铁，具体为：其束流入口边为直线，其束流出口边为一对上下对称的斜线，该上下对称斜线的倾斜方向为束流在出口边各自弯转的方向；该上下对称的斜线与束流弯转轨道的圆心到束流在二极铁出口处的连线构成二极铁出口边缘角；通过改变二极铁出口边缘角的大小调整二极铁的边缘场聚焦效果，并配合二极铁两边的四八极复合铁在Y方向的包络和X方向的包络，从而获得符合均匀化需求的理想相移。The aforementioned ultrashort symmetrical bend-type beam homogenization transmission line comprises a common transmission line and two branch transmission lines. The common transmission line, along the beam direction, sequentially includes: an accelerator outlet, a beam matching mechanism, a four-eight-pole composite iron A, and a diode. The common transmission line, along with the four-eight-pole composite iron B, the beam matching and homogenization effect observation mechanism A, and the terminal A of the first branch transmission line, constitutes the first bend-type beam homogenization transmission line. The common transmission line, along with the four-eight-pole composite iron C, the beam matching and homogenization effect observation mechanism B, and the terminal B of the second branch transmission line, constitute the second bend-type beam homogenization transmission line. The first bend-type beam homogenization transmission line and the second... The bending beam homogenization transmission line operates in a time-division multiplexing manner. The shared diode is a diode with symmetrical upper and lower edge angles at its exit edge. Specifically, its beam inlet edge is a straight line, and its beam outlet edge is a pair of symmetrical upper and lower oblique lines. The inclination direction of these symmetrical oblique lines is the direction in which the beam bends at the exit edge. The line connecting the center of the beam bending trajectory to the beam at the diode outlet forms the diode outlet edge angle. By changing the size of the diode outlet edge angle, the edge field focusing effect of the diode is adjusted, and in conjunction with the envelopes of the four-octet composite irons on both sides of the diode in the Y direction and the X direction, an ideal phase shift that meets the homogenization requirements is obtained. 10.根据权利要求8所述的一种基于四八极复合磁铁的超短束流均匀化传输线系统，其特征在于：所述通过优化设计二极铁的边缘角大小，从而获得符合均匀化需求的理想相移，即是：通过调整二极铁出口边缘角的大小，使得第一块四八极复合铁到目标点的Y方向的相位差接近180度、且第二块四八极复合铁到目标点的X方向的相位差接近0度、且两块四八极复合铁在X方向的相位差小于30度、且两块四八极复合铁在Y方向的相位差小于30度；10. The ultrashort beam homogenization transmission line system based on a quadrature-octet composite magnet according to claim 8, characterized in that: the ideal phase shift that meets the homogenization requirements is obtained by optimizing the design of the edge angle of the diode iron, that is: by adjusting the size of the exit edge angle of the diode iron, the phase difference in the Y direction from the first quadrature-octet composite magnet to the target point is close to 180 degrees, the phase difference in the X direction from the second quadrature-octet composite magnet to the target point is close to 0 degrees, the phase difference in the X direction between the two quadrature-octet composite magnets is less than 30 degrees, and the phase difference in the Y direction between the two quadrature-octet composite magnets is less than 30 degrees; 所述束流弯转轨道的圆心分别与束流在二极铁入口处和出口处的连线所构成的夹角为束流的弯转角度，在束流弯转角度一定的情况下，二极铁出口边缘角越大，则二极铁出口边在Y方向聚焦越强、X方向聚焦越弱；在束流弯转角度一定的情况下，二极铁出口边缘角越小，则二极铁出口边在X方向聚焦越强，Y方向聚焦越弱；The angle formed by the center of the beam deflection track and the lines connecting the beam at the inlet and outlet of the diode is the beam deflection angle. When the beam deflection angle is constant, the larger the edge angle of the diode outlet, the stronger the focusing in the Y direction and the weaker the focusing in the X direction. When the beam deflection angle is constant, the smaller the edge angle of the diode outlet, the stronger the focusing in the X direction and the weaker the focusing in the Y direction. 所述通过改变二极铁出口边缘角的大小调整二极铁的边缘场聚焦效果，并配合二极铁两边的四八极复合铁在Y方向的包络和X方向的包络，从而获得符合均匀化需求的理想相移，即是：当均匀化效果需要Y方向增强聚焦、X方向减弱聚焦以获得符合均匀化需求的理想相移时，在束流弯转角度一定的情况下，增大二极铁出口边缘角；当均匀化效果需要Y方向减弱聚焦、X方向增强聚焦以获得符合均匀化需求的理想相移时，在束流弯转角度一定的情况下，减小二极铁出口边缘角；The method involves adjusting the edge field focusing effect of the diode by changing the size of the diode exit edge angle, and coordinating with the envelopes of the four-octet composite iron on both sides of the diode in the Y and X directions to obtain an ideal phase shift that meets the homogenization requirements. Specifically: when the homogenization effect requires enhanced focusing in the Y direction and weakened focusing in the X direction to obtain an ideal phase shift that meets the homogenization requirements, the diode exit edge angle is increased when the beam bending angle is constant; when the homogenization effect requires weakened focusing in the Y direction and enhanced focusing in the X direction to obtain an ideal phase shift that meets the homogenization requirements, the diode exit edge angle is decreased when the beam bending angle is constant. 所述二极铁出口边缘角的可调范围≥0度且＜90度；The adjustable range of the electrode outlet edge angle is ≥0 degrees and <90 degrees; 二极铁出口边缘角的可调范围20度到60度；The adjustable range of the electrode outlet edge angle is 20 degrees to 60 degrees; 对于所述第一弯转型束流均匀化传输线，该出口边带有上下对称边缘角的二极铁布设在四八极复合铁A和四八极复合铁B之间，用超短传输线上出口边带有上下对称边缘角的二极铁代替常规二极铁，实现传输线超短的情况下相移的匹配和束流的聚焦；For the first curved beam homogenization transmission line, the diode with symmetrical upper and lower edge angles at the exit edge is arranged between the four-eight-pole composite iron A and the four-eight-pole composite iron B. The conventional diode is replaced by a diode with symmetrical upper and lower edge angles at the exit edge of the ultra-short transmission line to achieve phase shift matching and beam focusing in the case of ultra-short transmission line. 对于所述第二弯转型束流均匀化传输线，该出口边带有上下对称边缘角的二极铁布设在四八极复合铁A和四八极复合铁C之间，用超短传输线上出口边带有上下对称边缘角的二极铁代替常规二极铁实现传输线超短的情况下相移的匹配和束流的聚焦。For the second curved beam homogenization transmission line, the diode with symmetrical upper and lower edge angles at the exit edge is arranged between the four-eight-pole composite iron A and the four-eight-pole composite iron C. The diode with symmetrical upper and lower edge angles at the exit edge of the ultra-short transmission line is used to replace the conventional diode to achieve phase shift matching and beam focusing in the case of ultra-short transmission line. 11.一种基于权利要求1-10任意一项所述的一种基于四八极复合磁铁的超短束流均匀化传输线系统的用于四八极复合铁的励磁电流调整方法，其特征在于：包括以下步骤：11. A method for adjusting the excitation current of a four-octet composite iron based on an ultrashort beam homogenization transmission line system using a four-octet composite magnet, as described in any one of claims 1-10, characterized in that it includes the following steps: 步骤一、建立四极铁和八极铁的线圈电流二维数据对照表；该线圈电流二维数据对照表是基于四八极复合铁的线圈电流二维数据对照表；Step 1: Establish a two-dimensional data comparison table for coil current of four-pole iron and eight-pole iron; this two-dimensional data comparison table for coil current is based on the two-dimensional data comparison table for coil current of four-pole and eight-pole composite iron. 步骤二、实验测量，得到与二维电流数据对照表一一对应的四、八极磁场梯度测量值，从而得到磁场梯度的三维曲面样本数据库；上述磁场梯度的三维曲面样本数据库包括四极场磁场梯度三维曲面样本数据库，以及八极场磁场梯度三维曲面样本数据库；Step 2: Experimental measurement to obtain the four-pole and octole magnetic field gradient measurement values that correspond one-to-one with the two-dimensional current data comparison table, thereby obtaining a three-dimensional surface sample database of magnetic field gradients; the above three-dimensional surface sample database of magnetic field gradients includes a three-dimensional surface sample database of four-pole field magnetic field gradients and a three-dimensional surface sample database of octole field magnetic field gradients. 步骤三、使用三次样条函数，对该四极场磁场梯度三维曲面样本数据库，以及八极场磁场梯度三维曲面样本数据库进行二维插值，加密网格点密度；Step 3: Use cubic spline functions to perform two-dimensional interpolation on the three-dimensional surface sample database of the quadrupole magnetic field gradient and the octupole magnetic field gradient to refine the grid point density. 步骤四、选取四极场磁场梯度平面，该平面与四极场磁场梯度三维曲面样本数据库的曲面相交，得到满足该四极场磁场梯度的电流曲线；选取八极场磁场梯度平面，该平面与八极场磁场梯度三维曲面样本数据库的曲面相交，得到满足该八极场梯度的电流曲线；Step 4: Select a quadrupole magnetic field gradient plane. This plane intersects with the surface of the quadrupole magnetic field gradient three-dimensional surface sample database to obtain a current curve that satisfies the quadrupole magnetic field gradient. Select an octupole magnetic field gradient plane. This plane intersects with the surface of the octupole magnetic field gradient three-dimensional surface sample database to obtain a current curve that satisfies the octupole gradient. 步骤五、获得在线圈电流二维数据网格平面中满足四极场梯度的电流曲线和满足八极场梯度的电流曲线，并最终求出上述两条电流曲线的相交点；Step 5: Obtain the current curves that satisfy the quadrupole field gradient and the current curves that satisfy the octupole field gradient in the two-dimensional data grid plane of the coil current, and finally find the intersection point of the two current curves. 步骤六、用该相交点作为复合铁励磁电流的求解。Step 6: Use the intersection point as the solution for the excitation current of the composite iron. 12.一种基于权利要求1-10任意一项所述的一种基于四八极复合磁铁的超短束流均匀化传输线系统的直线型束流均匀化传输线调试方法，该调试方法还基于权利要求11所述的一种用于四八极复合铁的励磁电流调整方法；其特征在于，该调试方法包括以下步骤：12. A method for debugging a linear beam homogenization transmission line based on a four-octet composite magnet ultrashort beam homogenization transmission line system according to any one of claims 1-10, wherein the debugging method is further based on the excitation current adjustment method for a four-octet composite iron according to claim 11; characterized in that the debugging method includes the following steps: 步骤一、将四极铁和两块四八极复合铁的四极场、八极场电流置零；Step 1: Set the quadrupole field and octupole field currents of the quadrupole iron and the two quadrupole-octupole composite irons to zero; 步骤二、观察荧光靶上束流包络变化，并调整四八极复合铁A前面的四极铁电流，使得在四八极复合铁A附近X方向束流成腰；Step 2: Observe the changes in the beam envelope on the fluorescent target and adjust the quadrupole current in front of the quadrupole-octupole composite iron A so that the beam in the X direction near the quadrupole-octupole composite iron A forms a waist. 步骤三、观察荧光靶上束流包络变化，并调整四八极复合铁B前面的四八极复合铁A的四极铁电流，使得在四八极复合铁B附近Y方向束流成腰，保留此时的四八极复合铁A的四极场梯度；Step 3: Observe the changes in the beam envelope on the fluorescent target and adjust the quadrupole current of the quadrupole-octupole composite iron A in front of the quadrupole-octupole composite iron B so that the beam in the Y direction near the quadrupole-octupole composite iron B forms a waist, while preserving the quadrupole field gradient of the quadrupole-octupole composite iron A at this time. 步骤四、调整四八极复合铁B的四极铁电流，使得荧光靶上束流X方向包络与Y方向包络一致，得到圆束，保留此时的四八极复合铁B的四极场梯度；Step 4: Adjust the quadrupole current of the quadrupole-octapole composite iron B so that the X-direction envelope of the beam on the fluorescent target is consistent with the Y-direction envelope, to obtain a circular beam, and retain the quadrupole field gradient of the quadrupole-octapole composite iron B at this time. 步骤五、调整四八极复合铁A的八极场来调整束流在Y方向的均匀化效果，根据步骤三中记录的四八极复合铁A的四极场梯度和四八极复合铁A当前的八极场梯度，计算得到同时满足四八极复合铁A的四极场梯度和八极场梯度的相交点电流，保留此时的四八极复合铁A的八极场梯度；Step 5: Adjust the octagonal field of the four-octagonal composite iron A to adjust the beam homogenization effect in the Y direction. Based on the four-octagonal field gradient of the four-octagonal composite iron A recorded in Step 3 and the current octagonal field gradient of the four-octagonal composite iron A, calculate the intersection current that simultaneously satisfies the four-octagonal field gradient and the octagonal field gradient of the four-octagonal composite iron A, and retain the octagonal field gradient of the four-octagonal composite iron A at this time. 步骤六、若调整四八极复合铁A的八极场电流时束流的均匀化改变不明显，需要修改四八极复合铁A的四极场梯度进行相移匹配，使得四八极复合铁A到靶的Y方向相移接近180°，即根据调整后的四八极复合铁A的四极场梯度和步骤五保留的八极场梯度，计算得到同时满足四八极复合铁A的四极场梯度和八极场梯度的相交点电流；Step 6: If the beam homogenization is not significantly improved when adjusting the octet field current of the four-octet composite iron A, the four-octet field gradient of the four-octet composite iron A needs to be modified for phase shift matching so that the phase shift of the four-octet composite iron A to the target in the Y direction is close to 180°. That is, based on the adjusted four-octet field gradient of the four-octet composite iron A and the octet field gradient retained in step 5, the intersection current that simultaneously satisfies the four-octet field gradient and the octet field gradient of the four-octet composite iron A is calculated. 步骤七、调整四八极复合铁B的八极场来调整束流在X方向的均匀化效果，根据步骤四中记录的四八极复合铁B的四极场梯度和四八极复合铁B当前的八极场梯度，计算得到同时满足四八极复合铁B的四极场梯度和八极场梯度的相交点电流，保留此时的四八极复合铁B的八极场梯度；Step 7: Adjust the octagonal field of the four-octagonal composite iron B to adjust the beam homogenization effect in the X direction. Based on the four-octagonal composite iron B four-octagonal field gradient recorded in Step 4 and the current octagonal field gradient of the four-octagonal composite iron B, calculate the intersection current that simultaneously satisfies the four-octagonal field gradient and the octagonal field gradient of the four-octagonal composite iron B, and retain the octagonal field gradient of the four-octagonal composite iron B at this time. 步骤八、若调整四八极复合铁B八极场电流时束流的均匀化改变不明显，需要增大四八极复合铁B处的X方向束流包络。Step 8: If the uniformity of the beam current does not change significantly when adjusting the octet field current of the four-octet composite iron B, it is necessary to increase the beam current envelope in the X direction at the four-octet composite iron B. 13.一种基于权利要求1-10任意一项所述的一种基于四八极复合磁铁的超短束流均匀化传输线系统的弯转型束流均匀化传输线调试方法，该调试方法还基于权利要求11所述的一种用于四八极复合铁的励磁电流调整方法；其特征在于，包括以下步骤：13. A method for debugging a bent beam homogenization transmission line based on a four-octet composite magnet ultrashort beam homogenization transmission line system according to any one of claims 1-10, wherein the debugging method is further based on the excitation current adjustment method for a four-octet composite iron according to claim 11; characterized in that it includes the following steps: 步骤一、将四极铁和两块四八极复合铁的四极场、八极场电流置零；Step 1: Set the quadrupole field and octupole field currents of the quadrupole iron and the two quadrupole-octupole composite irons to zero; 步骤二、调整二极铁电流，使得束斑中心与荧光靶中心大致对齐；Step 2: Adjust the diode current so that the center of the beam spot is roughly aligned with the center of the fluorescent target; 步骤三、观察荧光靶上束流包络变化，并调整四八极复合铁A前面的四极铁电流，使得在四八极复合铁A附近X方向束流成腰；Step 3: Observe the changes in the beam envelope on the fluorescent target and adjust the quadrupole current in front of the quadrupole-octupole composite iron A so that the beam in the X direction near the quadrupole-octupole composite iron A forms a waist. 步骤四、观察荧光靶上束流包络变化，并调整二极铁前面的四八极复合铁A的四极场电流，在二极铁的边缘场和四八极复合铁A的四极场共同作用下，使得在四八极复合铁B附近束流Y方向成腰，保留此时的四八极复合铁A的四极场梯度；Step 4: Observe the changes in the beam envelope on the fluorescent target and adjust the quadrupole field current of the quadrupole-octupole composite iron A in front of the diode. Under the combined action of the edge field of the diode and the quadrupole field of the quadrupole-octupole composite iron A, the beam in the Y direction near the quadrupole-octupole composite iron B is made to form a waist, and the quadrupole field gradient of the quadrupole-octupole composite iron A at this time is preserved. 步骤五、调整四八极复合铁B的四极铁电流，使得荧光靶上束流X方向包络与Y方向包络一致，得到圆束，再次调整二极铁电流使束斑中心与靶中心对齐，保留此时的四八极复合铁B的四极场梯度；Step 5: Adjust the quadrupole current of the quadrupole-octapole composite iron B so that the X-direction envelope of the beam on the fluorescent target is consistent with the Y-direction envelope to obtain a circular beam. Adjust the diode current again to align the beam spot center with the target center, and retain the quadrupole field gradient of the quadrupole-octapole composite iron B at this time. 步骤六、调整四八极复合铁A的八极场来调整束流在Y方向的均匀化效果，根据步骤四中记录的四八极复合铁A的四极场梯度和四八极复合铁A当前的八极场梯度，计算得到同时满足四八极复合铁A的四极场梯度和八极场梯度的相交点电流，保留此时的四八极复合铁A的八极场梯度；Step 6: Adjust the octagonal field of the four-octagonal composite iron A to adjust the beam homogenization effect in the Y direction. Based on the four-octagonal field gradient of the four-octagonal composite iron A recorded in Step 4 and the current octagonal field gradient of the four-octagonal composite iron A, calculate the intersection current that simultaneously satisfies the four-octagonal field gradient and the octagonal field gradient of the four-octagonal composite iron A, and retain the octagonal field gradient of the four-octagonal composite iron A at this time. 步骤七、若调整四八极复合铁A的八极场电流时束流的均匀化改变不明显，需要修改四八极复合铁A的四极场梯度进行相移匹配，使得四八极复合铁A到靶的Y方向相移接近180°，即根据调整后的四八极复合铁A的四极场梯度和步骤六保留的八极场梯度，计算得到同时满足四八极复合铁A的四极场梯度和八极场梯度的相交点电流；Step 7: If the beam homogenization is not significantly improved when adjusting the octet field current of the four-octet composite iron A, the four-octet field gradient of the four-octet composite iron A needs to be modified for phase shift matching so that the phase shift of the four-octet composite iron A to the target in the Y direction is close to 180°. That is, based on the adjusted four-octet field gradient of the four-octet composite iron A and the octet field gradient retained in Step 6, the intersection current that simultaneously satisfies the four-octet field gradient and the octet field gradient of the four-octet composite iron A is calculated. 步骤八、调整四八极复合铁B的八极场来调整束流在X方向的均匀化效果，根据步骤五中记录的四八极复合铁B的四极场梯度和四八极复合铁B当前的八极场梯度，计算得到同时满足四八极复合铁B的四极场梯度和八极场梯度的相交点电流，保留此时的四八极复合铁B的八极场梯度；Step 8: Adjust the octagonal field of the four-octagonal composite iron B to adjust the beam homogenization effect in the X direction. Based on the four-octagonal field gradient of the four-octagonal composite iron B recorded in Step 5 and the current octagonal field gradient of the four-octagonal composite iron B, calculate the intersection current that simultaneously satisfies the four-octagonal field gradient and the octagonal field gradient of the four-octagonal composite iron B, and retain the octagonal field gradient of the four-octagonal composite iron B at this time. 步骤九、若调整四八极复合铁B八极场电流时束流的均匀化改变不明显，需要增大四八极复合铁B处的X方向束流包络。Step 9: If the uniformity of the beam current does not change significantly when adjusting the octet field current of the four-octet composite iron B, it is necessary to increase the beam current envelope in the X direction at the four-octet composite iron B.
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