JP2004247108A - Accelerator system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To optimize the injection efficiency of a charged particle (simply referred to a CP) into a main accelerator by using a means of estimating a CP emission timing from an injection device and a means of controlling a timing enabling the CP to enter the main accelerator by using a signal from the estimation means. <P>SOLUTION: The accelerator system comprises the main accelerator 14 for accelerating or decelerating the CP by a high frequency electric field, and the injection device for permitting the CP to enter the main accelerator. The injection device has a hollow ring-shaped path as a means of accelerating the CP until the CP obtains a velocity necessary for the injection, a ring-shaped central conductor having an acceleration gap for inducing a CP beam acceleration voltage, an acceleration core driving circuit having a rectifying circuit and a switching circuit, and a means of changing the orbit of the accelerated CP from an orbiting path to an emission orbit, and constructed so as to complete the injection and emission of the CP within one cycle of the operation frequency of the acceleration core. The accelerator system uses a means for estimating the CP emission timing from the injection device, and a means for controlling the CP injectable timing of the main accelerator 14 by using the signal from the estimation means. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an accelerator system for injecting charged particles from an injector that is an FFAG induction accelerator into a main accelerator that accelerates and decelerates charged particles by a high-frequency electric field.
[0002]
[Prior art]
As shown in Patent Document 1, a synchrotron (accelerator system) is a synchrotron radiation (SOR) system for various fields such as creation of an ultra-super LSI circuit, diagnosis in the medical field, molecular analysis, and structural analysis. The application of is expected.
[0003]
FIG. 12 shows an outline of a conventional SOR system disclosed in Patent Document 1. An electron beam generated by a charged particle generator (for example, an electron generator such as an electron gun) 1 is accelerated to near the speed of light by a linear accelerator (linac) 2, deflected by a bending electromagnet 4 of a beam transport unit 3, and inflated. The light enters the storage ring 7 via the septum electromagnet 15 (FIG. 13) of the stator 6. The electron beam incident on the storage ring 7 is converged by the converging electromagnets 9 (for the vertical direction) and 10 (for the horizontal direction) while being energized by the high-frequency electric field of the high-frequency accelerating cavity 8, and deflected by the bending electromagnet 11. Continue turning in the storage ring 7. Synchrotron radiation generated when the beam is deflected by the deflection electromagnet 11 is sent to, for example, an exposure device 13 through a beam channel 12, and is used as a light source for creating an ultra-super LSI circuit. A main accelerator 14 for accelerating and decelerating charged particles by a high-frequency electric field is constituted by the inflector 6 to the bending electromagnet 11, and an injector 5 for projecting charged particles to the main accelerator 14 is constituted by the electron generating devices 1 to the bending electromagnet 4. You.
[0004]
As shown in FIG. 13, the inflector 6 enters a new electron beam 18 at a position slightly deviated horizontally outward from a design trajectory (center trajectory) 17 of the electron beam 16 circulating in the storage ring 7. . At this time, a pertabeta (kicker electromagnet) 19 (schematically shown in the figure) provided at another location of the storage ring 7 is excited to cause the stored electron beam 16 in the storage ring 7 to be in the center of the storage ring 7. The bump 17 is kicked from the track 17 toward the inflector 6 to form a bump track 20 so that the incident electron beam 18 enters an acceptance (incidable area) formed around the bump track 20.
[0005]
[Patent Document 1]
JP-A-5-182793 (page 2, column 1, FIG. 2 and FIG. 3)
[Non-patent document 1]
Cole, Haxby, Jones, Pruett, and Terwilliger, "The Review of Scientific Instruments", Vol. 28, No. 6, June, 1957, p. 403-420
[0006]
[Problems to be solved by the invention]
As described in Patent Literature 1, when an incident electron beam is guided to an orbit, a perta beta (a kicker electromagnet) is excited so that the electron beam enters an acceptance (a region where light can enter). On the other hand, the excitation of the kicker electromagnet requires a time on the order of μs. Furthermore, in order to form a necessary magnetic field at the time of incidence, it is necessary to excite the electron beam at the same timing as that at the time of electron beam incidence. That is, if the excitation timing is not predicted before the electron beam is incident on the main accelerator, excitation cannot be performed properly, and the incident efficiency is reduced.
In addition, when a linear accelerator is used as an injector, an expensive klystron is required, which causes a problem that the price of the injector increases.
[0007]
In this invention, the means for predicting the emission timing of the charged particles from the injector, and the means for controlling the timing at which the charged particles can be incident on the main accelerator using a signal from the prediction means, to the main accelerator. The purpose is to increase the incident efficiency of charged particles.
Further, in the present invention, an FFAG (Fixed Field Alternating Gradient) induction accelerator, which can be driven by an inexpensive rectifier circuit and a switching circuit, is used as an injector to reduce the price of the injector.
[0008]
[Means for Solving the Problems]
An accelerator system according to the present invention is an accelerator system including a main accelerator for accelerating and decelerating charged particles by a high-frequency electric field, and an injector for injecting the charged particles into the main accelerator. As means for accelerating the charged particles, an annular path of the charged particle beam, a magnetic field generating means which bends the charged particle beam and guides it into the annular path and does not change from the entrance to the exit of the charged particle, and the hollow annular path An annular center conductor having an acceleration gap for inducing an acceleration voltage of the charged particle beam, an acceleration core provided to surround the center conductor, an acceleration core driving circuit having a rectifying circuit and a switching circuit, and Means for changing a charged particle from a circular orbit to an emission orbit, and from the incidence of the particle within one cycle of the operating frequency of the acceleration core. The accelerator system predicts the timing of emission of charged particles from the injector, and controls the timing at which the main accelerator can be charged using the signal from the predictor. Means.
[0009]
Further, in an accelerator system comprising a main accelerator for accelerating and decelerating charged particles by a high-frequency electric field, and an injector for injecting the charged particles into the main accelerator, the injector includes means for accelerating the charged particles to a speed required for the injection. An annular path of a charged particle beam, a magnetic field generating means which bends the charged particle beam and guides the charged particle beam into the annular path and does not change from the input to the emission of the charged particles, and An annular core conductor having an acceleration gap for inducing an acceleration voltage, an acceleration core provided to surround the center conductor, an acceleration core drive circuit having a rectifier circuit and a switching circuit, and the charged particles accelerated from the orbit. Means for changing to an emission trajectory, so as to complete the process from incidence to emission of particles within one cycle of the operating frequency of the acceleration core. Than it is.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiment 1 FIG.
The FFAG induction accelerator used as an injector in the present invention will be described. The next example is a device that applies electrons accelerated by an FFAG-type induction accelerator to an X-ray conversion target to generate X-rays. As for the FFAG induction accelerator for electron acceleration, only a prototype example in MURA (Midwestern University Research Association) in the United States can be found (see Non-Patent Document 1).
[0011]
FIG. 2 is a schematic diagram showing the FFAG induction accelerator. FIG. 3 is a sectional view taken along line AA of FIG. The electrons generated by the electron gun 21 are guided by an electrostatic deflector 22 to a circular orbit in an annular central conductor (a ring-shaped vacuum vessel made of copper or stainless steel) 23 having a hollow annular passage 30. Is done. The electrons are bent by the field magnetic field generated by the electromagnet (magnetic field generating means) 24 and are confined in the orbit. The above-mentioned field magnetic field (a weak magnetic field on the inside and a strong magnetic field on the outside) is kept constant while the electrons are accelerated, so that the orbital radius increases as the energy of the electrons increases, and the electrons orbit on the orbital radius determined by the energy. I do. However, an increase in the radius is suppressed by configuring the field magnetic field to be stronger as the radius is larger.
[0012]
An acceleration gap (acceleration gap) 25 is provided in the orbit, that is, the annular center conductor 23. When the magnetic flux Φ in the acceleration core 26 changes, an electric field (acceleration voltage) is applied to the acceleration gap 25 by the law of electromagnetic induction. Occurs. The electron is accelerated by this electric field each time the circuit is repeated, and becomes a high energy electron beam 27 and is extracted. The extracted high-energy electron beam 27 is irradiated on an X-ray conversion target 28 and converted into X-rays 29.
[0013]
Next, a method of applying an acceleration electric field will be described. The injector according to the present invention is of the induction acceleration type, and obtains high energy by orbiting particles passing many times during the acceleration phase of the alternating electric field applied to the acceleration gap 25. In other words, the process from the entrance to the exit of electrons is completed within one cycle of the alternating electromagnetic field. FIG. 4 shows the acceleration voltage V applied to the acceleration gap 25 and the timing of electron incidence and emission. T represents time. The figure shows the relationship between the acceleration phase 31, the acceleration time 32, and the incident time 33. Normally, the acceleration phase 31 of the sine wave used for driving the core is a half of the whole in which the acceleration voltage takes a positive value. However, at the beginning and the end of the acceleration phase 31, the acceleration voltage is greatly reduced, so that the particles cannot be accelerated, and the available acceleration time 32 is practically only 1/3 of the whole.
[0014]
Next, the relationship between the timing of electron incidence and emission and the acceleration time 32 and the incidence time 33 will be described. Electrons are introduced into the ring-shaped vacuum vessel 23 at the same time as the acceleration time 32 starts. The introduction is continued during the injection time 33. The end of the incident time 33 is a value obtained by subtracting the time required for accelerating the electrons from the end of the acceleration time 32. Electron emission is performed as follows. When an electron reaches a defined electron energy, it reaches a corresponding orbital radius. An emission septum (septum electromagnet) 15 is provided on the corresponding trajectory, and the trajectory of the beam incident on the septum is bent by an electric field or a magnetic field, and heads toward the emission port.
[0015]
Since the energy of an electron is the initial energy and the sum of the product of the elementary charge and the integral value of the acceleration voltage received by the electron during acceleration, the integral value of the acceleration voltage reaches the specified electron energy. This is the case when a certain value S is reached. That is, the timing of electron emission is when the integrated value of the acceleration voltage reaches S. FIG. 5 shows a general example of a core drive circuit that excites the acceleration core 26 and applies an acceleration voltage Vac to the acceleration gap 25 of the annular center conductor 23. A rectifier / smoothing circuit 35 is formed by the bridge circuit 34 composed of a thyristor and the capacitors C1 and C2. The switching circuit 36 is composed of an IGBT (Insulated Gate Bipolar Transistor) and a capacitor. Io, I1, I2, and I3 represent current, and Vap and Vac represent voltage. As shown in FIG. 4, a rectangular wave voltage is obtained for the Vap and Vac voltages.
[0016]
The components of this core drive circuit do not include an expensive klystron used in a linear accelerator, and can be configured at low cost. However, since the generated voltage directly shows the voltage fluctuation of an AC source (for example, 3φAC440V), if commercial power is used as it is, a voltage fluctuation of about several% occurs. As a result, the time during which the integrated value of the acceleration voltage becomes constant varies by several percent. Therefore, in the injector of the present invention, even if there is a variation of several percent, the means for predicting the emission timing of the charged particles from the injector and the timing at which the charged particle can be injected into the main accelerator by using the signal from the predicting means are used. It is desired to optimize the injection efficiency of charged particles into the main accelerator by using a controlling means.
[0017]
FIG. 1 is a configuration diagram showing an accelerator system according to Embodiment 1 of the present invention. The injector 41 is constituted by an FFAG-type induction accelerator, and the X-ray conversion target 28 is removed in FIG. Reference numeral 42 denotes a bending electromagnet. The main accelerator 14 is equivalent to the main accelerator shown in FIG. 12, and a description thereof will be omitted. Conventionally, a charged particle injector to the main accelerator 14 mainly uses a linear accelerator (LINAC). By replacing this with the FFAG induction accelerator 41, the klystron required for driving the linear accelerator can be eliminated. Since an inexpensive and highly reliable switching element can be used for driving the FFAG induction accelerator 41, there is an effect that the reliability of the entire system is improved and the cost can be reduced.
[0018]
Next, a means for predicting the emission timing of the charged particles from the injector and a means for controlling the timing at which the charged particle can be injected into the main accelerator by using a signal from the prediction means are used to charge the charged particles to the main accelerator. Optimization of the incident efficiency will be described. FIG. 6 is a diagram showing the relationship between the acceleration voltage, the electron beam emission time, and the kicker voltage. In FIG. 6A, Vo indicates a reference acceleration voltage, and V1 indicates an acceleration voltage when the voltage changes. The time at which the particles are emitted is the time at which the time integral of V reaches a predetermined value So.
Therefore, when the time integral of V (= S) is taken on the vertical axis as shown in FIG. 6B, a beam is emitted when a predetermined threshold value So is reached (beam emission time to, t1).
[0019]
On the other hand, the kicker voltage waveform of the kicker electromagnet (part beta) is as shown in FIG. If it does not enter the main accelerator 14 at the timing (injectable timing) 43 indicated by hatching of the kicker voltage waveform, the incidence efficiency is poor. That is, it is necessary to make the incidence on the main accelerator 14 after tdo (td1) (for example, after 10 μs) from the rising time tro (tr1) of the waveform. When it takes time longer than tdo from emission to incidence due to a long beam line from the FFAG induction accelerator 41 to the main accelerator 14, for example, the predetermined threshold value So is used as a trigger and an appropriate delay is provided. A beam can be incident at the timing 43 of the hatched portion of the voltage waveform. However, when the time t from the emission to the incidence is shorter than tdo (td1) (in FIG. 6C, the case of t << tdo (td1) is shown), the trigger is activated by the threshold value So. And excitation are not in time. In this case, the trigger (start) of the excitation of the kicker electromagnet (parter beta) may be set at the timing tr (tr1) of the threshold St lower than the threshold So shown in FIG. 6B.
[0020]
FIG. 7 is a diagram showing a timing control circuit for enabling charged particle incidence. Since the accelerating voltage is proportional to the voltage between both ends of the wiring linked to the accelerating core, the integrated value corresponding to S is obtained from the voltage V across the integrating circuit 44 (corresponding to a means for predicting the emission timing of charged particles). Do). The result of the integration is compared with the voltage Est corresponding to the value St by the comparator 45, and when it reaches this value, a trigger signal is generated (means for controlling the timing at which the main accelerator can enter charged particles using the signal from the prediction means). Corresponds to). In FIG. 7, reference numeral 46 denotes an operational amplifier. It goes without saying that a control circuit having similar characteristics can be constituted by a digital circuit.
[0021]
Embodiment 2 FIG.
FIG. 8 is a sectional view of an injector showing a main part of the second embodiment. FIG. 9 is a schematic sectional view of the annular center conductor 23 of FIG. The electrons incident from the electron gun are guided to the emission orbit from the emission septum 52 while drawing the spiral electron orbit 51. Since the emission timing is a timing at which electrons pass through a predetermined electron orbit, monitoring the electron trajectory can be used as a trigger. In this embodiment, a beam position is detected by disposing a beam detection electrode 53 around the electron beam. Numeral 54 denotes a beam orbit existing area, 55 denotes an incident orbit, 56 denotes a beam traveling direction, and 57 denotes an outgoing orbit.
[0022]
Since the beam detection electrode 53 is arranged so as to be in contact with the periphery of the beam trajectory, a beam current flows into the beam detection electrode 53. By monitoring this beam current with the ammeter 58, the timing at which the electron beam passes through a predetermined electron orbit can be detected, and a trigger signal for controlling the timing at which the main accelerator can enter charged particles can be extracted.
[0023]
In addition, instead of the beam detection electrode 53, a radiation generating target is provided around the orbit of the charged particle, and a signal induced by radiation generated when the peripheral charged particle beam is incident on the target is obtained. It is also possible to extract a trigger signal for controlling the timing at which charged particles can be incident.
[0024]
Embodiment 3 FIG.
In the second embodiment, the beam detection electrode is arranged at a position where the peripheral charged particle beam hits. However, from the viewpoint of reducing the beam loss, it is preferable that the electrode does not hit the electrode. Therefore, the beam position can be monitored by arranging the beam detection electrode at a position where the beam does not hit and measuring the inflow of charges induced by electrons into the electrode. In this case, there is an effect that the emission current intensity increases. FIG. 10 shows an example of an electrode arrangement provided for this purpose. FIG. 10 is a schematic sectional view of the annular center conductor 23. The charge induction electrode 59 is provided opposite to a position where the charge induction electrode 59 faces and approaches the peripheral charged particle beam in a state where the charged particle beam does not hit the peripheral surface. When electrons pass between the electrodes 59, a corresponding positive charge is induced on the electrodes 59 through the ammeter 58. By monitoring the current or monitoring the voltage signal electrostatically induced by the charged particle beam, a trigger signal for controlling the timing at which the main accelerator can enter charged particles can be extracted.
[0025]
Embodiment 4 FIG.
In the above description, the beam position was detected using the beam detection electrode. However, if a time period longer than tdo is required between the beam emission of the FFAG induction accelerator and the incidence on the main accelerator, the current flowing into the emission septum 52 is measured. By doing so, the emission timing can be known. In this case, there is an effect that it is not necessary to provide a beam detection electrode. Since a part of the beam normally hits the emission septum 52, the detection does not reduce the beam efficiency.
[0026]
FIG. 11 is a sectional view of an injector showing a main part of the fourth embodiment, and shows a configuration example in which an ammeter 58 is directly attached to the emission septum 52. By monitoring the current flowing into the emission septum 52, a trigger signal for controlling the timing at which the main accelerator can enter charged particles can be extracted. In addition, a trigger that controls the timing at which the main accelerator can enter charged particles is obtained by obtaining a signal induced by radiation generated when the charged particles enter the means (emission septum 52) for changing the charged particles from the orbit to the output orbit (the output septum 52). Signals can also be extracted.
[0027]
Although the above description has been made on the assumption that electrons are mainly used as charged particles, it goes without saying that the same can be applied to proton beams, heavy particles, and the like.
[0028]
【The invention's effect】
As described above, according to the accelerator system of the present invention, in an accelerator system including a main accelerator for accelerating and decelerating charged particles by a high-frequency electric field, and an injector for injecting the charged particles into the main accelerator, the injector includes: A means for accelerating the charged particles to a speed required for the incidence, an annular path of the charged particle beam, and a magnetic field generating means which bends the charged particle beam and guides the charged particle beam to the above-mentioned annular path and does not change from the input to the output of the charged particle. An annular core conductor having the hollow annular passage and having an acceleration gap for inducing an acceleration voltage of the charged particle beam; an acceleration core provided to surround the central conductor; an acceleration core having a rectifying circuit and a switching circuit A driving circuit, and means for changing the accelerated charged particles from the orbit to the emission orbit, within one cycle of the operating frequency of the acceleration core The accelerator system is configured to complete the process from incidence to emission of particles, and the accelerator system predicts the timing of emission of charged particles from the injector, and the charged particle injection of the main accelerator is performed using a signal from the prediction unit. Since there is a means for controlling the possible timing, the efficiency of charged particle injection into the main accelerator can be increased.
[0029]
Further, in an accelerator system comprising a main accelerator for accelerating and decelerating charged particles by a high-frequency electric field, and an injector for injecting the charged particles into the main accelerator, the injector includes means for accelerating the charged particles to a speed required for the injection. An annular path of a charged particle beam, a magnetic field generating means which bends the charged particle beam and guides the charged particle beam into the annular path and does not change from the input to the emission of the charged particles, and An annular core conductor having an acceleration gap for inducing an acceleration voltage, an acceleration core provided to surround the center conductor, an acceleration core drive circuit having a rectifier circuit and a switching circuit, and the charged particles accelerated from the orbit. Means for changing to an emission trajectory, so as to complete the process from incidence to emission of particles within one cycle of the operating frequency of the acceleration core. In, by using the injector the FFAG induction accelerator which can be driven by an inexpensive rectifier circuit and the switching circuit, it is possible to suppress the injector price.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an accelerator system according to Embodiment 1 of the present invention.
FIG. 2 is a schematic diagram showing an FFAG induction accelerator.
FIG. 3 is a sectional view taken along line AA of FIG. 2;
FIG. 4 is a diagram showing an acceleration voltage and timings of electron incidence and emission.
FIG. 5 shows a core drive circuit diagram.
FIG. 6 is a diagram showing a relationship among an acceleration voltage, an electron beam emission time, and a kicker voltage.
FIG. 7 is a diagram showing a timing control circuit capable of injecting charged particles.
FIG. 8 is a sectional view of an injector showing a main part of the second embodiment.
FIG. 9 is a schematic sectional view of the annular center conductor of FIG. 8;
FIG. 10 is a schematic cross-sectional view of an annular center conductor according to a third embodiment.
FIG. 11 is a sectional view of an injector showing a main part of a fourth embodiment.
FIG. 12 is a configuration diagram showing an outline of a conventional SOR system.
FIG. 13 is a configuration diagram showing an outline of an incidence part of a conventional main accelerator.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Electron generator 2 Linear accelerator 3 Beam transport part 4 Bending electromagnet 5 Injector 6 Inflector 7 Storage ring 8 High-frequency accelerating cavity 9 Converging electromagnet 10 Converging electromagnet 11 Bending electromagnet 12 Beam channel 13 Exposure device 14 Main accelerator 15 Septum electromagnet 16 Stored electron beam 17 Central orbit 18 Electron beam 19 Parter beta (Kicker electromagnet)
Reference Signs List 20 bump orbit 21 electron gun 22 electrostatic deflector 23 annular center conductor 24 magnetic field generating means 25 acceleration gap 26 acceleration core 27 high energy electron beam 28 X-ray conversion target 30 annular passage 34 bridge circuit 35 rectifying / smoothing circuit 36 switching circuit 41 FFAG type induction accelerator 44 integration circuit 45 comparator 52 emission septum 53 beam detection electrode 58 ammeter 59 charge induction electrode.

Claims (9)

In the accelerator system comprising a main accelerator for accelerating and decelerating charged particles by a high-frequency electric field, and an injector for injecting the charged particles into the main accelerator, the injector is a means for accelerating the charged particles to a speed required for incidence. An annular path for a charged particle beam, a magnetic field generating means that bends the charged particle beam into the annular path and does not change between the entrance and exit of the charged particles, and an acceleration of the charged particle beam having the hollow annular path An annular center conductor having an accelerating gap for inducing a voltage, an accelerating core provided to surround the center conductor, an accelerating core driving circuit having a rectifying circuit and a switching circuit, and an orbit for emitting accelerated charged particles from a circular orbit. Means for completing the process from the entrance to the exit of the particle within one cycle of the operating frequency of the acceleration core; An accelerator system comprising: means for predicting the timing of emission of charged particles from the injector; and means for controlling the timing at which the main accelerator can enter charged particles using a signal from the prediction means. . 2. The accelerator system according to claim 1, wherein the means for predicting the timing at which the charged particles are emitted from the injector is a means for monitoring a time integral signal of the acceleration voltage of the injector. 2. The accelerator according to claim 1, wherein the means for predicting the emission timing of the charged particles from the injector is provided around an orbit of the charged particles, and an incident current signal of the peripheral charged particle beam to the electrodes is obtained. system. The means for predicting the emission timing of charged particles from the injector is provided with a radiation generation target around the orbit of the charged particles, and a signal induced by radiation generated when the peripheral charged particle beam is incident on the target. 2. The accelerator system of claim 1, wherein the accelerator system is obtained. The means for predicting the timing of emission of charged particles from the injector obtains a voltage signal electrostatically induced by the charged particle beam at an electrode arranged to face the charged particle beam trajectory of the injector. 2. The accelerator system according to claim 1, wherein the accelerator system obtains a current signal flowing into the electrode. 2. An accelerator system according to claim 1, wherein said means for predicting the timing of emission of charged particles from said injector obtains a current signal of a charged particle beam incident on said means for changing charged particles from a circular orbit to an emission orbit. . The means for predicting the emission timing of the charged particles from the injector is to obtain a signal induced by radiation generated when the charged particles are incident on the means for changing the charged particles from the orbit to the emission orbit. Item 10. An accelerator system according to Item 1. The accelerator system according to any one of claims 1 to 7, wherein the means for controlling the timing at which charged particles of the main accelerator can be incident is means for controlling a start timing of a part beta of the main accelerator. In the accelerator system comprising a main accelerator for accelerating and decelerating charged particles by a high-frequency electric field, and an injector for injecting the charged particles into the main accelerator, the injector is a means for accelerating the charged particles to a speed required for incidence. An annular path for a charged particle beam, a magnetic field generating means that bends the charged particle beam into the annular path and does not change between the entrance and exit of the charged particles, and an acceleration of the charged particle beam having the hollow annular path An annular center conductor having an accelerating gap for inducing a voltage, an accelerating core provided to surround the center conductor, an accelerating core driving circuit having a rectifying circuit and a switching circuit, and an orbit for emitting accelerated charged particles from a circular orbit. Means for changing from the incidence to the emission of particles within one cycle of the operating frequency of the acceleration core. Accelerator system and butterflies.

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