JP2015133241A - Circular accelerator, circular acceleration system, and particle acceleration method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circular accelerator capable of instantaneously changing the emission energy of charged particles in an apparatus for accelerating charged particles and not requiring a change in the acceleration frequency of a magnetic field and a high-frequency acceleration electrode part for deflecting the trajectory of the charged particles. about.
A circular accelerator 100 includes a dee electrode 1 and dummy dee electrodes 2a to 2e for applying a high-frequency electric field for accelerating a charged particle beam, an electromagnet device for deflecting the charged particle beam, a dee electrode 1 and a dummy dee. Opening / closing devices 8a and 8b for partially short-circuiting the electrodes 2a to 2e, impedance adjustment circuit elements 7a1, 7a2, 7b1, and 7b2, and an insulating material 3 are provided.

[Selection] Figure 1

Description

  The present invention relates to a circular accelerator, a circular acceleration system, and a particle acceleration method, in particular, while accelerating a charged particle to a high energy by a high-frequency electric field while deflecting the charged particle in a magnetic field and orbiting a circular orbit, The present invention relates to a circular accelerator, a circular acceleration system, and a particle acceleration method for emitting accelerated charged particles to the outside.

  A conventional cyclotron or synchrocyclotron is a kind of circular accelerator. The charged particle beam is accelerated by the cyclotron by, for example, introducing a charged particle beam emitted from an ion source into a circular orbit in a plane perpendicular to a magnetic field, and a so-called Dee electrode installed on the circular orbit. This is achieved by applying a high-frequency AC voltage to accelerating the charged particle beam passing therethrough and increasing its energy.

A conventional circular accelerator will be described with reference to FIG. FIG. 13 shows a schematic configuration of a horizontal section of a conventional circular accelerator 1000.
A conventional circular accelerator 1000 with variable beam energy includes a dee electrode 1001 and a dummy dee electrode 1002. The Dee electrode 1001 is connected to a coaxial resonator, and includes a coaxial shield side 1005 and a wiring 1004 for grounding it. The beam is finally extracted by the electrostatic deflector electrode 1010 with its beam trajectory bent by an electrostatic high electric field.

  In the synchrocyclotron described in Patent Document 1, first, the acceleration frequency of the high-frequency voltage application electrode portion is accelerated at a high speed with an operation cycle of about 1 kHz during beam acceleration, and secondly, the high-frequency acceleration is performed. It is converged in the beam traveling direction by the principle of phase stability, and thirdly, it is a weakly converging magnetic field to converge the beam vertical direction, which are the main features. In the apparatus described in Patent Document 1, it is assumed that frequency modulation with a resonance frequency of, for example, a 1 kHz level is technically very difficult.

  In the cyclotron described in Patent Document 2, an ion beam extracted from an ion source is gradually accelerated each time it passes through an acceleration electrode section while circling by a deflection magnetic field generated by a deflection electromagnet. As the ion beam accelerates and the energy increases, the radius of the orbit becomes gradually larger and becomes a spiral orbit, and after the accelerated ion beam reaches the maximum energy, it is taken out of the accelerator by the extraction deflector. It is. Up to this point, it is the same as the synchrocyclotron.

  In order to stably accelerate charged particles in a cyclotron, first, a predetermined high-frequency accelerating electric field is applied in the beam traveling direction at the acceleration electrode in accordance with the timing of passage of the charged particles, and secondly in the beam vertical direction. It is necessary to give a predetermined convergence force. Third, there is no convergence force in the beam traveling direction.

In the cyclotron described in Patent Document 2, unlike the synchrocyclotron, the magnetic field distribution of the deflecting electromagnet is generated so that the circulating frequency of the charged particles does not change with acceleration, so there is no need to modulate the frequency of the high-frequency acceleration electric field. . This magnetic field is called an isochronous magnetic field. Since the isochronous magnetic field does not have a converging force in the beam traveling direction, for example, the magnetic field shaping accuracy of the electromagnet is increased to about 1 × 10 ⁻⁶ , and the acceleration voltage is increased to increase the beam in several hundred turns. It is set as the structure which takes out. Further, in order to obtain an isochronous magnetic field, it is necessary to obtain a magnetic field distribution that becomes stronger in the direction in which the radius is larger, and a large divergent force is generated in the vertical direction. In order to overcome this diverging force and obtain a vertical focusing force, the configuration of the deflecting electromagnet is a sector focusing cyclotron in which large magnetic pole gaps (valleys) and small magnetic pole gaps (crests) repeat alternately along the circumferential direction of the charged particles. Alternatively, it has an AVF cyclotron structure, and the magnetic pole shape is a spiral magnetic pole shape.

Special table 2008-507826 gazette Japanese National Patent Publication No. 5-501632 Japanese Patent Application No. 2011-244298

  In the conventional synchrocyclotron and cyclotron, in order to change the energy of the outgoing beam, it is necessary to change the magnetic field strength or the frequency of the high-frequency acceleration electric field. However, when the magnetic field strength is greatly changed, the spatial distribution of the isochronous magnetic field is also greatly changed, and there is a problem that it takes a long time to adjust the isochronous magnetic field. Further, in order to greatly change the acceleration frequency, it is necessary to largely change the resonance frequency of the high-frequency acceleration cavity, but there is a problem that it takes a long time to adjust the resonance frequency. For these reasons, it is not easy to instantaneously change the synchrocyclotron and the energy of the emitted beam of the cyclotron. Further, in beam extraction, it was assumed that the beam hits the electrode without straddling the radially inner electrode of the electrostatic deflector for beam extraction and the loss is relatively large because the beam orbit interval is narrow. .

  In the current synchrocyclotron and cyclotron, the energy cannot be changed by an accelerator, so the energy is changed by generating energy loss with a degrader after extracting the beam with a constant energy. When the beam performance deteriorates, there is a problem that the apparatus becomes large.

In view of the above points, an object of the present invention is to provide a circular accelerator, a circular acceleration system, and a particle acceleration method that can change or adjust the energy of an outgoing beam of the circular accelerator.

According to the first solution of the present invention,
A Dee electrode for applying a high-frequency electric field for accelerating the charged particle beam;
A dummy electrode divided into a first partial electrode including at least a quarter of a circle and one or a plurality of second partial electrodes including a portion excluding the first partial electrode;
There is provided a circular accelerator comprising an opening / closing device for connecting one or a plurality of the second partial electrodes to either the Dee electrode or the first partial electrode.

According to the second solution of the present invention,
A circular acceleration system,
A circular accelerator,
A beam transport system for transporting the beam output from the circular accelerator;
A beam irradiation system for irradiating a target with the beam transported by the beam transport system;
The circular accelerator is
A Dee electrode for applying a high-frequency electric field for accelerating the charged particle beam;
A dummy electrode divided into a first partial electrode including at least a quarter of a circle and one or a plurality of second partial electrodes including a portion excluding the first partial electrode;
There is provided a circular acceleration system comprising: an opening / closing device for connecting one or a plurality of the second partial electrodes to either the Dee electrode or the first partial electrode.

According to the third solution of the present invention,
A particle acceleration method in a circular accelerator,
In the circular accelerator,
A dummy dee electrode divided into a dee electrode, a first partial electrode including at least a quarter of a circle, and one or a plurality of second partial electrodes including a portion excluding the first partial electrode By applying a high frequency electric field to accelerate the charged particle beam,
By connecting one or more of the second partial electrodes to one of the dee electrode or the first partial electrode by a switchgear device,
A particle acceleration method characterized by generating an ExB drift due to a magnetic field B and a primary harmonic electric field E on a beam trajectory of the charged particle beam, and changing the output energy of the charged particle beam to output the charged particle beam. Provided.

According to the present invention, it is possible to provide a circular accelerator, a circular acceleration system, and a particle acceleration method capable of changing or adjusting the energy of the exit beam of the circular accelerator.

It is a figure which shows schematic structure of the energy variable type | mold circular accelerator by 1st Example of this invention. It is a figure which shows the perpendicular | vertical cross-sectional schematic structure of the energy variable type | mold circular accelerator by 1st Example of this invention. It is a figure which shows the outline of the beam drift orbit of the energy variable type | mold circular accelerator by 1st Example of this invention. It is a figure which shows the relationship between the dee electrode short circuit start radius re, the impedance Z of an impedance adjustment circuit, and the emitted beam energy at the time of applying this invention to the cyclotron apparatus for PET chemical | medical agent manufacture. It is a figure which shows schematic structure of the energy variable type | mold circular accelerator by the 2nd Example of this invention. It is a figure which shows schematic structure of the energy variable type | mold circular accelerator by the 3rd Example of this invention. It is a figure which shows schematic structure of the low-loss beam extraction system of the circular accelerator by the 4th Example of this invention. It is explanatory drawing of the corresponding | compatible table which shows an example of the relationship between emitted beam energy and a switch state. It is a figure (A) which shows explanation of an operation pattern which changes beam energy dynamically during operation by a switch and impedance for adjustment. It is a figure (B) which shows description of the driving | operation pattern which changes beam energy dynamically during driving | operation with a switch and the impedance for adjustment. 1 is an example of a PET drug generation system in which a circular accelerator is used. It is an example of the particle beam therapy system in which a circular accelerator is used. It is a figure which shows schematic structure of the circular accelerator provided with the control part. It is a figure which shows schematic structure of the conventional circular accelerator.

The present invention and this embodiment can be applied to all types of circular beam accelerators. Here, as an example, a variable energy circular accelerator and its beam energy changing method are described.

1. Overview

In this embodiment, in the circular accelerator, an electrode for applying a high-frequency electric field for accelerating the charged particle beam, an electromagnet device for deflecting the charged particle beam, and a portion between the dee electrode and the dummy dee electrode for applying the high-frequency electric field are partially provided. To solve the above-mentioned problems by providing a first-order harmonic electric field with a certain radius or more, drifting the center of the orbit, and extracting the beam with different energy Can do.

  According to the present embodiment, this apparatus uses this circular accelerator to freely change the output beam energy while keeping the beam deflection magnetic field constant, and to widen the interval between the outermost orbits of the beam. The take-out efficiency can be increased.

According to the present embodiment, for example, a primary harmonic electric field is applied above a certain radius to drift the center of the orbit, and the impedance of the high frequency circuit and the dummy de-electrode that is divided into a plurality of parts in the radial direction can be adjusted. By providing the structure, the energy of the exit beam of the circular accelerator can be changed or adjusted. In addition, according to the present embodiment, since neither the change of the magnetic field nor the acceleration frequency is changed, the high performance, downsizing, and cost reduction as a whole circular accelerator system including the energy changing device of the outgoing beam are possible. It becomes. Further, according to the present embodiment, it is possible to extract a highly efficient beam with little beam loss, which can contribute to higher performance.

2. Circular accelerator

A circular accelerator which is a preferred embodiment of the present invention will be described with reference to FIG.

FIG. 1 is a schematic configuration diagram of a horizontal section of a circular accelerator 100 according to the present embodiment. Hereinafter, the energy change of the charged particle beam by the circular accelerator 100 of the present embodiment will be described.

  The circular accelerator 100 with variable beam energy according to the present embodiment includes a dee electrode 1, dummy dee electrodes 2 a, 2 b, 2 c, 2 d, 2 e that are divided and insulated in a semicircular shape by an insulating material 3, and a dummy having a radius greater than or equal to re. Circuit elements Z1 to Z8, Za and Zb for adjusting the impedance characteristics of the cavity resonator (for example, an electrical equivalent circuit of a circular accelerator) for connecting the Dee electrode to the Dee electrode and the switch unit 8 Impedance adjusting circuit elements 7a1, 7a2, 7b1, and 7b2. The Dee electrode 1 is connected to a coaxial resonator, and has a coaxial shield side 5 and a wiring 4 for grounding it. The dummy Dee electrode 2 is grounded by a ground wiring 6. The beam is finally extracted by the electrostatic deflector electrode 10 by bending the beam trajectory with an electrostatic high electric field.

  In this embodiment, the dummy dee electrode is divided and divided into five parts. However, the structure is not limited to five, and any structure may be used as long as it is divided and divided into a plurality of parts. Here, the dee electrode is an electrode on the high voltage side of two electrodes that are installed on a circular orbit and generate a high electric field between the electrodes to accelerate particles, Is defined as an electrode on the ground potential side of two electrodes for accelerating particles. A charged particle beam generated by an ion source (not shown) is incident on the center of the circular accelerator 100, and a Dee electrode 1 to which coaxial mode high frequency power is transmitted from a 1 / 4λ coaxial waveguide (cavity resonator). And the dummy dee electrodes 2a, 2b, 2c, 2d, and 2e that are divided and concentrically concentrically formed by the insulating material 3 are sequentially accelerated by a high-frequency accelerating electric field. In the region where the Dee electrode 1 and the dummy Dee electrodes 2a to 2e are present, a magnetic field is applied perpendicularly to the paper surface direction. Finally, the charged particle beam is extracted at the electrostatic deflector electrode 10 disposed outside the Dee electrode.

  The circular accelerator 100 of this embodiment is different from the conventional circular accelerator shown in FIG. 13 mainly in that the dummy dee electrode 2 is divided into a plurality of concentric semicircular shapes, and the divided dummy Each of the dee electrodes 2a, 2b, 2c, 2d and 2e is insulated by the insulating material 3, and whether or not each of the dee electrodes 2a, 2b, 2c, 2d and 2e is connected to the dee electrode 1 Are provided with switch units 8a and 8b, and circuit elements 7a1, 7a2, 7b1 and 7b2 for adjusting a change in impedance characteristics of the coaxial resonator due to the connection. Each of the dummy dee electrodes 2b, 2c, 2d, and 2e is connected to either the dee electrode 1 or the dummy dee electrode 2a by the switch portions 8a and 8b.

  FIG. 2 is a schematic view of a vertical cross section of the circular accelerator 100 with variable beam energy according to the present embodiment. As shown in FIG. 2, the circular accelerator 100 with variable beam energy of the present embodiment includes a main magnetic field coil 12 for deflecting a charged particle beam, an auxiliary magnetic field coil 13 for adjusting a magnetic field, An electromagnet core 14 and a high frequency power source 15 are provided.

  Next, a method in which the circular accelerator 100 operates by changing the energy of the charged particle beam will be described. A switch unit 8a is connected between the D electrode 1 for transmitting a high frequency and the dummy D electrodes 2a to 2e, whereby the D electrode 1 is branched into a plurality of parallel and each dummy D electrode 2a via the impedance adjustment circuit 7a1. To 2e. Further, a switch portion 8b is connected between the dummy dee electrode 2a on the ground side and the dummy dee electrodes 2b, 2c, 2d, and 2e, so that the dummy dee electrode 2a is branched into a plurality in parallel, and the impedance adjusting circuit 7b1 is provided. To the dummy dee electrodes 2b to 2e. The switch part 8a is normally open, the dee electrode 1 is disconnected from each dummy dee electrode 2a-2e, and the switch part 8b is normally closed, and each dummy dee electrode 2b-2e is on the ground side. Since it is connected to the dummy electrode 2a, an alternating electric field is generated between the gaps, and the particles are accelerated in synchronization with the alternating electric field. In the acceleration, when the shunt impedance decreases, the acceleration electric field also decreases. Shunt impedance is the capacitance of the gap between the dee electrode and dummy dee electrode when the cavity structure (cavity resonator) including the dee electrode, dummy dee electrode, and λ / 4 coaxial waveguide is described in an equivalent circuit. And the cavity inductance and their electrical resistance. Lowering the shunt impedance is equivalent to shorting the gap between the dee electrode and the dummy dee electrode so that an electric field cannot be applied, and therefore it is necessary to adjust so that the shunt impedance does not decrease. The impedance adjustment circuit elements 7a1, 7a2, 7b1, and 7b2 are adjustment elements for preventing the shunt impedance of the high-frequency cavity from being lowered and keeping the shunt impedance high. The approximate value of the shunt impedance is designed to be 80 kΩ in, for example, the paper THE DESIGN AND COMMISSIONING OF THE RF SYSTEM FOR CYCIAE-14 CYCLOTRON, Processings of IPAC 2013 (WEPFI026). By closing the switch portion 8a connected to each of the dummy dee electrodes 2a to 2e, the dee electrode and each dummy dee electrode are connected. In other words, by independently controlling the opening and closing of each of the switch portions 8a, the connection between each of the dummy dee electrodes 2a to 2e and the dee electrode 1 can be controlled, and ON / OFF of application of an alternating electric field to charged particles can be controlled. The short-circuit connection between the dee electrode 1 and the dummy dee electrodes 2a to 2e creates a non-electric field region between the dee electrode and the dummy dee electrode, and the primary harmonic electric field is applied to the charged particles. A drift occurs in the direction perpendicular to the deflection magnetic field B. The energy of the outgoing beam is changed by adjusting the drift of the generated beam trajectory depending on which radius de dummy dee electrodes 2a to 2e are short-circuited with the dee electrode and how much the shunt impedance is adjusted. Moreover, the impedance of each impedance adjustment circuit element 7a1, 7a2, 7b1, 7b2 can be made into an appropriate value. In addition, you may comprise the switch part 8a and the switch part 8b by one switchgear.

The setting of the switch unit 8a and the switch unit 8b may be determined and fixed in advance, or may be controlled variably (dynamic) by a control unit (see FIG. 12).
FIG. 8 is an explanatory diagram of a correspondence table indicating what state (ON or OFF) each switch has for each energy. FIG. 9 shows an operation pattern in which the energy is changed by dynamically changing the switch during operation.
When fixed, according to FIG. 8, each of the switch units 8a and 8b is set so that predetermined beam energy can be output.

FIG. 12 is a diagram illustrating a schematic configuration of a circular accelerator including a control unit. When control is performed in a variable (dynamic) manner, the control unit 30 stores a correspondence table as shown in FIG. 8 in advance, and the control unit 30 sets and inputs a predetermined change in beam energy output over time. The switches 8a and 8b are controlled with reference to the table of FIG.
As an example, when the energy is switched from 5 MeV to 10 MeV, the control unit 30 controls as follows. As shown in FIG. 9A, when 5 MeV is initially set, the switch unit 8a turns ON between Za and z1 to z4, and the switch unit 8b turns OFF between Zb and z5 to z8. . Next, when switching to 10 MeV, Zb and z1 are turned off by the switch unit 8a, Zb and z2 to z4 are turned on, Zb and z5 are turned on by the switch unit 8b, Zb And z6 to z8 are set to OFF.

  Further, the switching can be performed relatively continuously by controlling the impedance by the control unit 30. As an example, when the energy is continuously changed between 5 MeV and 10 MeV, as shown in the state of each switch in FIG. 8 and the waveform in FIG. Adjust between finite values of. That is, as shown in FIG. 9B, for example, in the middle of switching from 5 MeV to 10 MeV, the control unit 30 controls the impedance adjustment circuit element 7a2 so that Z1 is Z1 + dz1, and a predetermined value (here, 8 MeV). After being increased discretely (stepwise) or continuously, the switch part 8a is controlled to open the dummy dee electrode 2b and the dee electrode 1, and the switch part 8b is controlled to control the dummy dee electrode 2b and dummy. Dee electrode 2 is closed. In the figure, an example in which dz1 is adjusted discretely (stepwise) is shown, but it can also be adjusted continuously.

  According to this embodiment, the dummy dee electrode from the center to a predetermined radius re is not connected to the dee electrode to generate an accelerating electric field to accelerate the beam, and the dummy dee electrode outside the radius re is connected to the dee electrode. Thus, the charged particle beam is drifted by the primary harmonic electric field without generating an acceleration electric field.

  FIG. 3 shows an example of the beam trajectory at this time. In FIG. 3, the beam trajectory of the 4-sector AVF cyclotron is a spiral trajectory up to the radius re, and since the dee electrode is short-circuited with the dummy dee electrode outside the re, no electric field is generated. A beam drift due to the next harmonic electric field occurs, the beam trajectory 11 is shifted from the center and drifts outward, and the charged particle beam is taken out by the electrostatic deflector 10.

  FIG. 4 shows an example of the relationship between the resistance value of the impedance adjustment circuit element with respect to the beam emission energy and the radius re at which connection is started. As shown in FIG. 4, the beam emission energy can be freely changed by adjusting the radius re for starting the short circuit between the dee electrode and the dummy dee electrode and the impedance adjustment circuit element of the resonance cavity. As the insulating material for the concentric semicircular dummy dee electrode that is divided into multiple parts, for example, if Mylar, polycarbonate, Kapton, etc. are used, the dielectric breakdown electric field has a high solid insulation performance of 100 kV / mm or more. A sufficient structural design is possible.

  According to the present embodiment, the output beam energy can be changed by the circular accelerator 100, the conventional energy changing degrader is not required, and the beam energy loss caused by the degrader is prevented and the beam performance is not deteriorated due to the increase in emittance. be able to. Furthermore, since the degrader is unnecessary, the entire accelerator system can be reduced in size and cost.

  According to the present embodiment, the dee electrode 1 for applying an accelerating electric field to the charged particles and the concentric semicircular dummy dee electrode 2 insulated in multiple divisions are partially connected, so that the output beam of the circular accelerator 100 The energy can be changed and adjusted, and neither the change of the magnetic field nor the acceleration frequency is changed, so the overall circular accelerator system including the energy change device of the outgoing beam is improved in performance, size, and low. Costs can be reduced, and high-efficiency beams can be extracted with less beam loss, which can contribute to higher performance.

  A circular accelerator according to a second embodiment of the present invention will be described with reference to FIG. FIG. 5 shows a schematic configuration of a horizontal cross section of the circular accelerator 101 of the present embodiment.

  In the circular accelerator 101 of the present embodiment, as in the circular accelerator 100 of the first embodiment, the dee electrode 1 and the dummy dee electrode 2b are connected by the switch unit 8a, thereby forming a non-electric field region between the gaps. Accordingly, a drift is generated in the beam trajectory by the primary harmonic electric field and the deflecting magnetic field B thereby, and the charged particle beam is extracted by changing the beam energy. In this example, the dummy dee electrode 2b that is not connected to the dee electrode 1 by the switch unit 8a is connected to the dummy dee electrode 2a by the switch unit 8b. In the circular accelerator 100 of the first embodiment, the dummy dee electrode is divided into a plurality of concentric semicircles and insulated from each other. However, in the circular accelerator 101 of this embodiment, the dummy dee electrode 2 is divided into two parts. It was set as the made dummy dee electrode.

  Comparing the circular accelerator 101 according to the present embodiment and the circular accelerator 100 in which the dummy dee electrodes are concentrically divided and insulated as in the first embodiment, the circular accelerator 101 according to the present embodiment has two dummy dee electrodes divided and insulated. Since it has only one configuration, the manufacturing cost is reduced, and the energy can be continuously changed by adjusting the electric field at the gap distance from the Dee electrode by adjusting the impedance adjustment circuit element. However, since the wide region between the dee electrode 1 and the dummy dee electrode 2b is substantially free of electric field, the beam trajectory drifts in a wider region, so that the isochronism of the beam circulation is disrupted in the wide region, so that It may be assumed that the particles can be accelerated to the target energy. For this reason, it may be necessary to install, for example, an additional trim coil to compensate for the isomagnetic magnetic field.

  According to the present embodiment, the output beam energy can be changed by the circular accelerator 101, the conventional energy changing degrader is not required, and the beam energy loss caused by the degrader is prevented and the beam performance is not deteriorated due to the increase in emittance. be able to. Furthermore, since the degrader is unnecessary, the entire accelerator system can be reduced in size and cost.

  A circular accelerator according to a third embodiment of the present invention will be described with reference to FIG. FIG. 6 shows a schematic configuration of a horizontal section of the circular accelerator 102 of the present embodiment.

  Similar to the circular accelerator 100 of the first embodiment, the circular accelerator 102 of the present embodiment has a gap between the Dee electrode 1 and any one or more of the dummy Dee electrodes 2a to 2e connected by the switch unit 8a. A region with substantially no electric field is formed between them, and a drift is generated in the beam trajectory by the primary harmonic electric field and the deflection magnetic field B thereby to take out the charged particle beam by changing the beam energy. Each of the dummy dee electrodes 2b, 2c, 2d, and 2e is connected to either the dee electrode 1 or the dummy dee electrode 2a by the switch portions 8a and 8b. In this example, the dee electrode 1 and the dummy dee electrodes 2d and 2e are connected by the switch unit 8a, and the dummy dee electrode 2a and the dummy dee electrodes 2b and 2c are connected by the switch unit 8b. In the circular accelerator 100 of the first embodiment, the dummy dee electrode 2 is configured to be divided into a plurality of concentric semicircles. However, the circular accelerator 102 of the present embodiment is configured to divide the dummy dee electrode 2 into a plurality of lines linearly. It was.

  Comparing the circular accelerator 100 in which the dummy dee electrode is divided and insulated into concentric semicircular shapes as in the first embodiment and the circular accelerator 102 in the present embodiment, the circular accelerator 102 in the present embodiment is divided and insulated dummy dee Since the electrodes are linear, the manufacturing cost is reduced and the energy can be changed. In the case of the circular accelerator 102 of this embodiment, the electric field of the divided dummy dee electrodes 2a, 2b, 2c, 2d and 2e is applied only in a certain direction. As the beam trajectory drifts, it is assumed that isochronism breaks down and particles can be normally accelerated to the target energy. For this reason, it may be necessary to install, for example, an additional trim coil to compensate for the isomagnetic magnetic field.

  According to the present embodiment, the output beam energy can be changed by the circular accelerator 102, the conventional energy changing degrader becomes unnecessary, and the beam performance loss due to the beam loss caused by the degrader and the deterioration of the beam performance due to the increase in emittance are prevented. be able to. Furthermore, since the degrader is unnecessary, the entire accelerator system can be reduced in size and cost.

  A circular accelerator according to a fourth embodiment of the present invention will be described with reference to FIG. FIG. 7 shows a schematic configuration of a horizontal cross section of the circular accelerator 103 of the present embodiment.

  In the circular accelerator 103 of the present embodiment, as in the circular accelerator 100 of the first embodiment, the dee electrode 1 and the dummy dee electrode 2b are connected by the switch portion 8a, so that a substantially no electric field region is formed between the gaps. A high-efficiency beam is formed by generating a drift in the beam trajectory by the primary harmonic electric field and the deflection magnetic field B formed thereby, widening the beam orbit interval, and reducing the amount of loss of the beam hitting the deflector electrode. It is the structure which takes out. In this example, the dummy dee electrode 2b that is not connected to the dee electrode 1 by the switch unit 8a is connected to the dummy dee electrode 2a by the switch unit 8b. The difference between the circular accelerator 103 of the present embodiment and the circular accelerator 100 of the first embodiment is that the purpose is not to change the beam energy but to extract the beam with high efficiency.

  Generally, in a circular accelerator that deflects an orbit with a magnetic field B and accelerates particles with a high-frequency electric field generated by a high-frequency accelerating cavity, an ExB drift can be generated by the primary harmonic electric field E and the deflecting magnetic field B. The above-described Examples 1 to 4 are similarly applied as an exit beam energy changing system or an exit beam high-efficiency extraction method, and the high performance of the entire system including the charged particle beam extraction and the energy changing device. , Miniaturization, and cost reduction can be achieved.

According to the present embodiment, the output beam energy can be changed by the circular accelerator 103, a conventional energy changing degrader becomes unnecessary, and deterioration of the beam performance due to the increase in emittance caused by the beam energy loss caused by the degrader is prevented. be able to. Furthermore, since the degrader is unnecessary, the entire accelerator system can be reduced in size and cost.

3. system

Here, an example of a system using circular acceleration will be described with reference to FIG.

1 shows an example of a proton cyclotron system for PET drug generation. This system of FIG. 10 includes a cyclotron 16 (circular accelerator 100) and a beam transport system 19 for transporting the outgoing beam to the PET target 20 without loss. The beam transport system 19 further includes a beam focusing electromagnet 17 and a beam. And a deflection electromagnet 18. The general specifications required for this system are, for example, an acceleration frequency of about 50 MHz, a beam current peak value of about 1.0 mA, an incident energy of 30 keV, and an output energy of about 10 MeV. The high frequency acceleration voltage required in this case is ˜100 kV, and the beam deflection magnetic field is ˜1T.

  In addition, a present Example is applicable also to the production | generation of another substance other than PET chemical | medical agent.

The present embodiment can also be applied to a cyclotron for a particle beam therapy system that treats cancer by changing the beam energy according to the depth of the tumor.
FIG. 11 shows an example of a particle beam therapy system. As shown in FIG. 11, the particle beam therapy system includes a cyclotron 16 (circular accelerator 100) for generating a high energy beam for treatment, a beam transport system 19, and a rotation for irradiating the cancer patient 25 with a beam 24 from multiple directions. A gantry 21, an electromagnet 22 for scanning the beam in the horizontal direction, and an electromagnet 23 for scanning the beam in the vertical direction are provided.

4). Appendix

In the first to fourth embodiments, the charged particle beam has been described. However, even if it is an electron or a positron, the energy changing method in the circular accelerator of the present embodiment is naturally valid if it is a beam.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  Each of the above-described configurations, functions, processing units, processing means, and the like may be realized by hardware by designing a part or all of them with, for example, an integrated circuit. Each of the above-described configurations, functions, and the like may be realized by software by interpreting and executing a program that realizes each function by the processor. Information such as programs, tables, and files for realizing each function can be stored in a memory, a hard disk, a recording device such as an SSD (Solid State Drive), or a recording medium such as an IC card, an SD card, or a DVD.

  Further, the control lines and information lines indicate what is considered necessary for the explanation, and not all the control lines and information lines on the product are necessarily shown. Actually, it may be considered that almost all the components are connected to each other.

1 Dummy electrode side 2, 2a, 2b, 2c, 2d, 2e Dummy electrode 3 Insulating material 4 Coaxial resonator shield side ground wiring 5 Coaxial resonator shield side 6 Dummy electrode ground wiring 7, 7a1, 7a2, 7b1, 7b2 Cavity resonator impedance characteristic adjustment circuit element 8, 8a, 8b Switch or switch 9 Charged particle 10 Electrostatic deflector 11 Drift trajectory 12 of charged particle beam Main magnetic field coil 13 Auxiliary magnetic field coil 14 Electromagnetic core 15 High frequency Power supply 16 Cyclotron 17 Beam focusing electromagnet 18 Beam deflection electromagnet 19 Beam transport system 20 PET target 21 Rotating gantry 22 Horizontal beam scanning electromagnet 23 Vertical beam scanning electromagnet 24 Particle beam 25 Patient to be treated

100, 101, 102, 103, 104 Circular accelerator

Claims (15)

A Dee electrode for applying a high-frequency electric field for accelerating the charged particle beam;
A dummy electrode divided into a first partial electrode including at least a quarter of a circle and one or a plurality of second partial electrodes including a portion excluding the first partial electrode;
A circular accelerator comprising: an opening / closing device for connecting one or a plurality of the second partial electrodes to either the Dee electrode or the first partial electrode.
The circular accelerator according to claim 1, wherein
An insulating material for insulating each of the first and second partial electrodes;
Further comprising an impedance characteristic adjusting circuit element connected to the switchgear,
The switchgear is
A first switching device for connecting or opening one or a plurality of the second partial electrodes and the dee electrode, respectively;
One or a plurality of the second partial electrodes connected or opened to the dee electrode by the first switchgear, and a second switchgear for opening or connecting the first partial electrode, respectively. A circular accelerator comprising:
The circular accelerator according to claim 1, wherein
In the dummy dee electrode, one or a plurality of the partial electrodes are concentrically divided in the radial direction, and the first partial electrode is divided into one quarter circle and one other half of the half circle. 4 includes a concentric circular portion on the center side, and the second partial electrode is obtained by dividing a portion excluding the first partial electrode in the other ¼ circle into one or a plurality of concentric circles. A circular accelerator characterized by that.
The circular accelerator according to claim 3, wherein
The circular accelerator is characterized in that the second partial electrode is one.
The circular accelerator according to claim 4, wherein
The dummy dee electrode is divided near the maximum radius of the beam trajectory of the charged particle beam or near the output,
A circular accelerator characterized in that an ExB drift due to a magnetic field B and a primary harmonic electric field E is generated in the vicinity of a maximum radius of a beam trajectory, and a charged particle beam is taken out by widening an orbital interval of the charged particle beam.
The circular accelerator according to claim 1, wherein
The first partial electrode of the dummy dee electrode includes one quarter of one half of the circles,
The circular accelerator is characterized in that the second partial electrode is obtained by linearly dividing a portion excluding the first partial electrode into a plurality of portions.
The circular accelerator according to claim 1, wherein
A circular accelerator characterized in that the open / close state of the open / close device is fixedly set in advance.
The circular accelerator according to claim 1, wherein
A table storing the open / close state of the switchgear according to beam energy;
A circular accelerator comprising: a control unit that controls opening and closing of the switchgear according to one or more preset beam energies with reference to the table.
The circular accelerator according to claim 8, wherein
A circuit element provided between the dee electrode and each of the second partial electrodes of the dummy dee electrode, for adjusting impedance characteristics;
When the beam energy is switched, the control unit discretely or continuously increases the impedance connected to the second partial electrode that is switched from connection to release to a predetermined value with respect to the circuit element. A circular accelerator characterized by switching the switchgear after the control.
The circular accelerator according to claim 2, wherein
The impedance characteristic adjusting circuit element is:
A first circuit element provided between the first switchgear and the dee electrode for adjusting impedance characteristics;
A second circuit element provided between the first switchgear and each second partial electrode of the dummy dee electrode for adjusting impedance characteristics;
A third circuit element provided between the second switchgear and the dummy dee electrode for adjusting impedance characteristics;
A circular accelerator comprising a fourth circuit element provided between the second switchgear and each second partial electrode of the dummy electrode for adjusting impedance characteristics.
The circular accelerator according to claim 1, wherein
A magnetic field coil for deflecting a charged particle beam;
A high frequency power source that generates a charged particle beam and is incident on a central portion of the circular accelerator;
A circular accelerator comprising a deflector electrode for bending and extracting a beam trajectory.
A circular accelerator according to claim 1;
A circular acceleration system for generating a drug or substance, comprising: a beam transport system for transporting an outgoing beam from the circular accelerator to a target.
A circular accelerator according to claim 1;
A beam transport system for transporting the beam output from the circular accelerator;
A rotating gantry for irradiating the target from multiple directions with the beam transported by the beam transport system;
A circular acceleration system for particle beam therapy, comprising: an electromagnet for scanning the beam horizontally and vertically.
A circular acceleration system,
A circular accelerator,
A beam transport system for transporting the beam output from the circular accelerator;
A beam irradiation system for irradiating a target with the beam transported by the beam transport system;
The circular accelerator is
A Dee electrode for applying a high-frequency electric field for accelerating the charged particle beam;
A dummy electrode divided into a first partial electrode including at least a quarter of a circle and one or a plurality of second partial electrodes including a portion excluding the first partial electrode;
A circular acceleration system comprising: an opening / closing device for connecting one or a plurality of the second partial electrodes to either the Dee electrode or the first partial electrode.
A particle acceleration method in a circular accelerator,
In the circular accelerator,
A dummy dee electrode divided into a dee electrode, a first partial electrode including at least a quarter of a circle, and one or a plurality of second partial electrodes including a portion excluding the first partial electrode By applying a high frequency electric field to accelerate the charged particle beam,
By connecting one or more of the second partial electrodes to one of the dee electrode or the first partial electrode by a switchgear device,
A particle accelerating method comprising: generating an ExB drift due to a magnetic field B and a primary harmonic electric field E on a beam trajectory of the charged particle beam; and changing the output energy of the charged particle beam to output the charged particle beam.

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