JP2596292B2 - Circular accelerator, operation method thereof, and medical system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circular accelerator for orbiting and emitting a charged particle beam, a method for operating the same, and a medical device.
Medical treatment system .

[0002]

2. Description of the Related Art In a conventional circular accelerator, a charged particle beam such as an electron or an ion is accelerated and orbited, and the charged particle beam emitted from the orbit is transported by a transport system for use in a physical experiment or medical treatment. I've been. In the conventional charged particle beam emission, AIP Conference Proceedings No. 127 (1983) (AIP Conference
The resonance of the betatron oscillation of the beam has been used as discussed in Proceedings, pages 53-61.

[0003] The resonance of betatron oscillation is the following phenomenon. The charged particles orbit while oscillating left and right or up and down, and this oscillation is called betatron oscillation. The frequency per revolution of the orbit of the betatron oscillation is called tune,
The tune can be controlled by a bending electromagnet or a quadrupole electromagnet provided on the orbit. In the above conventional example, when the tune is brought close to an integer ± 整数 and the resonance generating six-pole electromagnet provided on the orbit is excited, the orbiting charged particles have an amplitude greater than a certain boundary. The betatron oscillation amplitude of charged particles increases sharply. This phenomenon is called resonance of betatron oscillation, and the boundary is called a stability limit. The magnitude of the betatron oscillation amplitude at the stability limit of the resonance depends on the deviation from the tune integer ± １ ／, and the smaller the deviation is, the smaller. Therefore, in the prior art, the tune is gradually approached to an integer ± １ ／, that is, the magnitude of the stability limit is gradually reduced, and resonance occurs first in charged particles having a large betatron oscillation amplitude among the orbiting charged particles. Thereafter, resonance is sequentially generated in the charged particles having a small vibration amplitude to gradually emit a charged particle beam.

[0004]

In the above prior art,
There were the following problems.

First, when the stability limit is reduced, the beam collides with the deflector wall provided at the emission position, and the charged particles cannot be taken out. That is, although the betatron oscillation amplitude of the charged particles is substantially uniformly distributed, it is not possible to extract the charged particles having the betatron oscillation amplitude of a certain fixed amplitude or less, so that the emission efficiency of the charged particles is reduced.

Second, the orbital gradient of the charged particles emitted at the emission position at each stability limit changes. Since the exit deflector is provided at a fixed angle to the orbit,
A charged particle beam emitted at a certain angle or more from this angle collides with the inner wall of the transport system including the emission deflector and disappears. As a result, there is a problem that the emission efficiency of the charged particles is low and the emission current changes and cannot be controlled. Further, when the orbital gradient of the charged particles changes, the emission position at the exit of the transport system also changes.

Third, there is a problem that the beam diameter changes due to a change in the amount of increase in the amplitude of the betatron oscillation for each round of the circular accelerator during the emission of the beam.

Fourth, as a result, the emission position at the exit of the transport system, the emission current, the beam diameter, and the like change during the emission, which is not preferable for physical experiments or medical use.

Fifth, when the excitation amount of the quadrupole electromagnet is changed to reduce the magnitude of the stability limit, the stability limit once disappears and then reappears, so that resonance occurs in some beams. However, there is a problem that the light emission efficiency is reduced without performing the above.

A first object of the present invention is to provide a circular accelerator having a high extraction efficiency of a charged particle beam during circulation and a method of operating the circular accelerator.
And medical systems .

A second object of the present invention is to provide a circular accelerator having a large emission current, an operation method thereof, and a medical system .

A third object of the present invention is to provide a circular accelerator having an almost constant position of an output beam from a transport system and a method of operating the circular accelerator.

A fourth object of the present invention is to provide a circular accelerator whose beam diameter emitted from the transport system is substantially constant and a method of operating the circular accelerator.

A fifth object of the present invention is to provide a circular accelerator capable of controlling an emission current and a method of operating the same.

[0015]

The object of the present invention is achieved.
The feature of the circular accelerator according to claim 1 is that the charged particle beam
Means for orbiting along the orbit (3, 5, 7 and 8);
Betatron of the charged particle beam outside the stability limit of sound
Means (9/30) for bringing vibrations into resonance, and the load
Extraction deflation for extracting an electron particle beam from the orbit
A circular accelerator having a resonator (15);
Oscillation amplitude of the charged particle beam within the stability limit of neutrons
To increase the charged particle beam within the stability limits of the resonance.
Oscillations that move the resonance outside the stability limit of the resonance
Having amplitude increasing means (14/31/36/37)
It is in. 3. The circular accelerator according to claim 2, which achieves the object of the present invention.
The feature is provided along the orbit of the charged particle beam
Bent magnets (3), quadrupole magnets (5 and 7) and high
Frequency accelerating cavity (8), said charge outside the stability limit of resonance
Resonance excitation to make betatron oscillation of particle beam resonance state
Electromagnet (9/30) and the charged particle beam
The output deflector (15) to be taken out of the orbit
A circular accelerator equipped with the charged particle beam
During the launch, the stability limit of the resonance is substantially constant.
In order to control the amount of excitation of the quadrupole electromagnets (5 and 7),
Control means for controlling and electromagnet for resonance excitation (9/30)
Control means for controlling the amount of excitation of the
The betatron oscillation amplitude of the charged particle beam
The charged particle beam within the stability limit of the resonance.
To increase the amplitude of betatron oscillations moving outside the stability limit
(14/31/36/37).

The circular add according to claim 3, which achieves the object of the present invention.
The feature of the speed changer is the betatron oscillation amplitude increasing means (14 /
31) is provided along the orbit of the charged particle beam.
Means for generating a time-varying magnetic field (23, 2
4, 25 and 26/31 and 31 power supplies)
is there. The circular accelerator according to claim 4, which achieves the object of the present invention.
The feature is a means for generating a time-varying magnetic field (23,
24, 25 and 26/31 and 31)
Signal power source (24/3)
1 power supply) and the signal whose time variation is irregular is applied.
Means (23, 25 and
And 26/31).

According to the fifth aspect of the present invention, there is provided a circular processing apparatus comprising:
The feature of the speed changer is the betatron oscillation amplitude increasing means (14 /
31) is provided along the orbit of the charged particle beam.
Means for generating a time-varying electric field (23, 2
4, 25 and 26/31 and 31 power supplies)
is there. The circular accelerator according to claim 6, which achieves the object of the present invention.
The feature is a means for generating a time-varying electric field (23,
24, 25 and 26/31 and 31)
Signal power source (24/3)
1 power supply / 36), and the signal whose time change is irregular is marked.
Means (23,
25 and 26/31).

According to the seventh aspect of the present invention, there is provided a circular add
The feature of the speed changer is the betatron oscillation amplitude increasing means (14 /
31) is a charged particle caused by application of a high-frequency signal.
-Frequency application to increase the betatron oscillation amplitude of the daughter beam
(14/31). The purpose of the present invention
9. The feature of the circular accelerator of claim 8 wherein the high frequency signal is achieved.
Is that it is a high-frequency signal whose time change is irregular.
The features of the circular accelerator according to claim 9, which achieves the object of the present invention.
The high frequency signal is the betatron oscillation of the charged particle beam
High-frequency signal containing frequency components synchronized with
You. The circular accelerator according to claim 10, which achieves the object of the present invention.
The feature is that the betatron oscillation amplitude increasing means (14)
And means (34 and 36) for controlling the intensity of the frequency signal.
That is.

The circular shape according to claim 11, which achieves the object of the present invention.
The feature of the accelerator operation method is the orbit around the charged particle beam.
Orbit along the charged particle beam outside the stability limit of the resonance.
The betatron oscillation of the
The charged particle beam that has entered the resonance state through the
Operation of the circular accelerator to take out the system from the orbit
In taking out the charged particle beam,
Betatron oscillation of a charged particle beam within the stability limit of the resonance
Charged particles within the stability limit of the resonance by increasing the dynamic amplitude
Moving the beam outside the stability limits of the resonance.
You. The circular accelerator according to claim 12, which achieves the object of the present invention.
The operation method is characterized by a charged particle beam within the stability limit of resonance.
Increase in the betatron oscillation amplitude of the
Is performed in a substantially constant state.

The circular shape according to claim 13, which achieves the object of the present invention.
The characteristic of the accelerator operation method is that charged particles within the stability limit of resonance
The rate of increase of the betatron oscillation amplitude of the
It is to be. The circle according to claim 14, which achieves the object of the present invention.
The characteristic of the operation of the accelerator is that the charge within the stability limit of resonance
To increase the betatron oscillation amplitude of a particle beam
Applied to the high frequency marking means provided along the orbit
It is to change the intensity of the high frequency signal. Eye of the invention
The circular accelerator according to claim 15, which achieves the target
Increase the signal strength during the extraction of the charged particle beam
Is to add.

The medical treatment according to claim 16, which achieves the object of the present invention.
The feature of the system is that the charged particle beam follows the orbit
Orbiting means (3, 5, 7 and 8), stability limit of resonance
Resonance of the betatron oscillation of the charged particle beam outside
Means (9) for bringing the charged particle beam into a state
Emission deflector (15) to be taken out from orbit
Circular accelerator and the deflector for emission (15)
Transport the charged particle beam to the treatment room (103)
Medical system with a beam transport system (102)
Of the charged particle beam within the resonance stability limit.
Increase the Tatron oscillation amplitude to within the stability limit of the resonance
The charged particle beam out of the stability limit of the resonance
Betatron oscillation amplitude increasing means (14) should be provided.
And there. The medical system according to claim 17, which achieves the object of the present invention.
The feature of the stem is that the beam transport system (102)
Main beam transport duct connected to reflector (15)
(102), contacted by this beam transport duct,
Transport of multiple branch beams guided to the operating room (103)
Duct and from the main beam transport duct (102) forward
Transfer of charged particle beam to each branch beam transport duct
Having switching means (105) for switching transmission
is there. 19. The medical system of claim 18, which achieves the object of the present invention.
The features of the system are provided in the treatment room (103),
Irradiates a charged particle beam guided by a beam transport duct
A beam irradiation device for irradiating an object is provided.

[0022]

The principle and operation of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a general outline of the present invention, which is a circular accelerator that emits an accelerated beam. The circular accelerator includes bending electromagnets 3, quadrupole electromagnets 5, 7, resonance excitation electromagnet 9, emission deflector 13, and the like. The resonance excitation electromagnet 9 is an electromagnet that generates a multipole magnetic field for generating resonance. The coordinate system is s for the beam circling direction, x for the horizontal direction,
Let y be the vertical direction. The beam circulates while vibrating around the design trajectory 1 which is a circling trajectory. The betatron oscillation amplitude differs for each particle constituting the beam, and particles having a large amplitude to small particles are mixed. Therefore, the beam diameter during orbit of the design orbit 1 is determined by the maximum value of the betatron oscillation amplitude. The frequency of one orbit of the betatron oscillation per orbit is called tune, and the horizontal tune is νx and the vertical tune is νy. The values of the horizontal and vertical tunes νx and νy can be adjusted by the excitation amounts of the converging quadrupole electromagnet 5 and the diverging quadrupole electromagnet 7.

The quadrupole electromagnets 5 and 7 are adjusted to set the horizontal tune νx or the vertical tune νy to an integer ± p / q.
(Reduced fraction), and when the electromagnet 9 for resonance excitation is excited, the amplitude of particles having a betatron oscillation amplitude larger than the stability limit increases due to resonance. The resonance at this time is called a q-order resonance. Hereinafter, a case where a beam is extracted from the horizontal direction will be described by taking a third-order resonance as an example.

The quadrupole electromagnets 5 and 7 are adjusted so that the horizontal tune νx approaches an integer ± １ ／ and the resonance excitation electromagnet 9 (in the case of the tertiary resonance, a six-pole electromagnet is used), the vibration amplitude is reduced. Third-order resonance is excited by large particles. The position in the s direction at which the output deflector 13 of FIG. 1 is installed is so, and x and dx for each round of the beam at s = so
FIG. 2 shows the relationship (phase space) of / ds. The dashed line in FIG. 2 indicates the stability limit in the phase space. Particles outside the stability limit, that is, particles whose betatron oscillation amplitude is larger than the stability limit, have a sharp increase in oscillation amplitude every round due to resonance. The number given to the particle exceeding the stability limit in FIG. 2 indicates the number of turns. The stability limit becomes smaller as the deviation of the tune vx from the integer ± 1/3 is smaller and the strength of the multipole magnetic field for generating resonance is larger. Reference numeral 20 in FIG. 2 (indicated by 20i on the inside and 20o on the outside) indicates the electrodes of the deflector 13 for emission shown in FIG. 1, and particles that collide with the electrodes 20 have been lost and have entered the region between the electrodes 20. The particles are emitted out of the circular accelerator.

The orbital gradient dx / ds of the emitted particles at the position of the exit deflector is substantially equal to A as can be seen from FIG. A is set to, for example, an angle formed between the orbit and the deflector for emission. The diameter of the beam emitted from the circular accelerator is determined by the beam diameter entering the deflector for emission. In the case of tertiary resonance, the 3
The amount of increase in displacement for each revolution (in the case of q-order resonance, the amount of displacement increase for every q revolutions) is referred to as turn separation Ts. Ts increases as the distance from the stability limit increases, and decreases as the stability limit decreases. Therefore, when the stability limit is reduced by changing the tune to emit particles having a small betatron oscillation amplitude as in the prior art, the turn separation Ts also decreases. Can not get over,
The beam ceases to collide with the wall. Beam output efficiency is
Assuming that the thickness of the exit deflector wall is Td, the primary evaluation is (Ts-Td) / Ts. Therefore, the smaller the stability limit, the lower the emission efficiency. Typically,
As the betatron oscillation amplitude is smaller, the distribution efficiency of the circulating beam is larger, so that the emission efficiency is lower. Therefore, in the present invention,
Charged particles that are within the stability limit are moved out of the stability limit by increasing the betatron oscillation amplitude. As a result, even particles having a small betatron oscillation amplitude that cannot be extracted unless the stability limit is reduced can be emitted while maintaining a certain degree of turn separation Ts. Therefore,
High output efficiency, or greater circular accelerator emission current and
The driving method and the medical system can be provided.

Next, the operation of keeping the stability limit substantially constant will be described. As described above, the stability limit can be controlled by adjusting the amount of excitation of the tune and the multipole electromagnet for generating resonance. FIG. 2 shows the trajectory of the representative particle in the phase space, and other particles move along the trajectory in the figure. That is, many particles exist between the trajectories in FIG. The beam emitted from the beam having the increased vibration amplitude is the beam incident between the two electrodes 20i and 20o of the output deflector. Therefore, if the stability limit is kept constant, not only the gradient of the output beam, that is, the output angle, can be kept constant, but also the output beam diameter and the output position can be kept constant. As described above, when the emission position is constant and the turn separation Ts is constant, the emission efficiency (Ts-T
d) / Ts also becomes constant. The gradient of the output beam and the turn separation Ts can be changed by selecting a tune when setting the stability limit before the output, that is, by adjusting the excitation amount of the quadrupole electromagnet and the excitation amount of the resonance excitation electromagnet. The output efficiency is constant and large.

Next, the emittance representing the beam characteristics will be described. The emittance of the beam indicates the area occupied by the beam in the phase space, and is proportional to the product of the beam size and the distribution width of the orbit gradient. For example, the emittance of a beam circling within the stability limit shown in the phase space of FIG.
It is equal to the area enclosed by the broken line in FIG. On the other hand, the phase space near the exit deflector electrode 20 of the exit beam is shown in FIG.
Shown in The emittance of the output beam is equal to the product of the width ΔX of the beam entering between the deflector electrodes 20i and 20o and the change width ΔP of the orbit gradient. When resonance is generated with the above-mentioned stability limit being substantially constant, the variation width ΔP of the orbital gradient shown in FIG. 6 can be suppressed to a negligible level, and the emittance of the output beam can be kept constant and small. it can.

Next, the means for increasing the betatron oscillation amplitude of particles within the stability limit of the resonance will be described. As means for increasing the vibration amplitude of particles within the stability limit, any of the following means is used. (1) Apply a time-varying magnetic field to the beam. (2) Apply a time-varying electric field to the beam. (3) Colliding particles different from the output beam with the output beam
You.

The magnetic field of (1) is applied in the vertical direction (y direction) when the emitting surface is a horizontal surface, and is applied in the horizontal direction (x direction) when the emitting surface is a vertical surface. This means that although the change in the orbital gradient for each revolution is small, the orbital gradient of the beam is changed by the magnetic field, and the accumulation of the beam increases the oscillation amplitude of the beam.
The time change of the magnetic field may be regular or irregular. As a device for applying a magnetic field to the beam, an electromagnet, a parallel linear electrode, a plate electrode, an arc electrode, or the like can be used. By passing a time-varying current through these devices, a time-varying magnetic field is applied to the beam and the betatron oscillation amplitude increases.

The electric field of (2) is applied in the circling direction of the beam, ie, in the s direction, or in the horizontal direction (x direction) when the emitting surface is a horizontal surface, and in the vertical direction when the emitting surface is a vertical surface. (Y direction). When an electric field is applied in the s direction, the energy of the beam changes. When the energy of the beam changes, the radius of curvature of the trajectory in the bending electromagnet portion changes, so that the center trajectory position of the betatron oscillation changes, and as a result, the betatron oscillation amplitude changes. When an electric field is applied in the x direction or the y direction, similarly to the magnetic field of (1), a transverse force is applied to the beam to change the orbit gradient,
Increase the betatron oscillation amplitude. The time change of the electric field may be regular or irregular. The electric field can be applied by applying a time-varying current to parallel linear, flat, or arc electrodes, by applying a time-varying voltage to a button or plate electrode, or by applying a high-frequency voltage to a high-frequency cavity. Is applied. Therefore, in the case of an electric field, the electric field can be decomposed into the s direction and the x direction or the y direction regardless of the direction of application, so that the above two effects occur and the amplitude of the betatron oscillation can be increased.

When a time-varying signal is applied to an electrode or a cavity, a magnetic field is also generated at the same time as the electric field. Therefore, when the effect of the electric field is mainly used, the effect of the magnetic field is superimposed, and the effect of the magnetic field is mainly used. The effect of the electric field is also superimposed. In either case, since the amplitude of the betatron oscillation increases, a beam can be emitted as in the case of a single case.

When an electric field or a magnetic field that changes with time perpendicular to the beam traveling direction is applied as described above to increase the betatron oscillation amplitude of the beam, the frequency component is synchronized with the betatron oscillation. It is desirable to include. This is because when an electromagnetic field including a frequency component synchronized with the betatron oscillation is applied to the beam, the electromagnetic field is synchronized with the betatron oscillation, and the amplitude of the betatron oscillation can be efficiently increased. The frequency of the electromagnetic field synchronized with the betatron oscillation is the fractional part of the tune, or 1
It can be obtained from the product of the value obtained by subtracting the decimal part of the tune from and the orbital frequency. A multipole electromagnet is required to generate resonance when the beam is emitted, but when the multipole electromagnet is excited, the tune of the beam changes depending on the betatron oscillation amplitude. That is, the tune of the beam having a large betatron oscillation amplitude is different from the tune of the beam having a small betatron oscillation amplitude. Also,
Since the betatron oscillation amplitude of the beam is continuously distributed from a large value to infinity, the tune of the beam is also continuously distributed. Therefore, if a plurality of frequency components are provided in an externally applied electromagnetic field and the values are set to values close to the tune of the beam, the betatron oscillation amplitude can be efficiently increased. In particular, since the tune of the beam is continuously distributed as described above, it is desirable to use an electromagnetic field containing noise having continuous frequency components and containing frequency components synchronized with betatron oscillation. However, even at a single frequency, it is possible to increase the betatron oscillation amplitude by using an electromagnetic field having a frequency approximately equal to the tune of the distributed beam. In this case, a larger electromagnetic field strength is required as compared with the above high frequency having a plurality of frequency components.

Another effect when the above-mentioned noise is used in an electromagnetic field applied from the outside will be described. When ripples are included in the current of the electromagnet of the accelerator, the tune changes with time in synchronization with this, and the magnitude of the stability limit in FIG. 5 changes. Therefore, in the conventional emission method in which the stability limit is gradually reduced as shown in FIG. 5, since the magnitude of the stability limit becomes smaller while oscillating in synchronization with the current ripple, the beam may be emitted intermittently. high. On the other hand, when an electromagnetic field whose intensity changes randomly is applied to the beam, the beam spreads in the phase space shown in FIG. 5 and the betatron oscillation amplitude increases. At this time, if the change amount of the betatron oscillation amplitude due to noise is ΔAn, the time is t, and the constant is D,
(ΔAn ² ) = Dt. Here, (ΔAn ² ) indicates the average value of the change in vibration amplitude of the beam for all particles. From this, the time derivative of the vibration amplitude change of the beam is 0.5 (D /
t) ⁰ · ⁵ next, although the large rate of increase within a short period of time, the rate of increase in long-term decreases. Therefore, even if the oscillation amplitude of the beam is slowly increased over a long period of time, the increase width of the betatron oscillation amplitude can be larger than the change width of the stability limit within a time period of about the ripple period of the electromagnet current.
The beam can be emitted with little influence from the power supply ripple.

Further, in (3), particles other than the beam circling the circular accelerator are introduced into the circular accelerator and collide with the circular beam. As a result of the collision-induced scattering, the orbital gradient changes and the betatron oscillation amplitude of the orbiting beam increases.
The particles to be collided may be neutral particles or charged particles. The particles to be collided may be injected as a gas, or may be provided as a thin film in the accelerator and collide with the beam.

Finally, the operation of the means for controlling the increasing rate of the betatron oscillation amplitude will be described. The emission current can be adjusted by controlling the rate of increase of the betatron oscillation amplitude of particles within the stability limit. When the betatron oscillation amplitude is increased using the above-mentioned electromagnetic field (1) or (2), the intensity of an electric field or a magnetic field is changed by changing the signal strength applied to an electrode or the like. When the emission current is increased and the beam is emitted quickly, the intensity of the applied signal is increased. When the emission current is reduced and the beam is emitted slowly, the intensity of the applied signal is decreased. By using the same method, the emission current can be temporally changed in the emission process. Furthermore, when keeping the emission current constant,
The rate of increase is adjusted according to the beam distribution during orbit.

The amount of the beam emitted per unit time is
At that time, it is roughly proportional to the number of particles of the beam circling the accelerator. Since the number of particles of the orbital beam decreases with the emission, in order to emit the beam at a constant rate, it is necessary to increase the speed of increase of the betatron oscillation amplitude by increasing the electromagnetic field intensity during the emission. In this way, since the amount of the emission current can be controlled by the increasing speed of the betatron oscillation amplitude, the start and stop of the emission can be controlled by the start and stop of the application of the electromagnetic field. Therefore, not only a predetermined operation plan, but also beam emission / stop at the request of the beam user side is possible, and further, emergency stop of beam emission can be performed.

In the case of using the method (3), by adjusting the number of other particles to be put in the circular accelerator, the adjustment can be performed in the same manner as in the case where the betatron oscillation amplitude is increased by the electromagnetic field.

In addition to the above-described adjustment of the emission current, a method of adjusting the emission current by changing the magnitude of the stability limit by adjusting the tune or changing the excitation amount of the resonance excitation electromagnet may be added. The emission current can be controlled in the same manner as described above.

The gradient of the output beam and the turn separation Ts are changed by selecting a tune when setting a stability limit before the output, that is, by adjusting the excitation amount of the quadrupole electromagnet and the excitation amount of the resonance excitation electromagnet. be able to.

[0040]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention, in which protons having an energy of about 20
It is a figure which shows the device structure of the circular accelerator which emits after accelerating to eV. The circular accelerator is an injector 1 for inputting a beam 17 from a pre-stage accelerator 16 via a beam transport system 18.
5, a high-frequency accelerating cavity 8 for imparting energy to the incident beam 17, a bending electromagnet for bending the beam trajectory 3, a quadrupole electromagnet 5, 7 for controlling the betatron oscillation of the beam, and 6 for exciting resonance at the time of emission. The pole electromagnet 9, a high frequency applying device 14 for increasing the betatron oscillation amplitude of particles within the stability limit of resonance by applying a time-varying magnetic field to the beam, and the particles having the increased betatron oscillation amplitude to the beam transport system for emission. It comprises an emission deflector 13 for emitting light. Among these devices, the six-pole electromagnet 9,
The high-frequency applying device 14 and the deflector 13 for emission are
It is used only in the emission process after accelerating the beam to the target energy.

The trajectory of the beam incident from the injector 15 is bent by the bending electromagnet 3 in the course of orbit. Also, 4
In the polar electromagnet, the trajectory gradient can be changed by a force proportional to the deviation from the design trajectory 1. The quadrupole electromagnet 5 changes the orbit gradient so as to converge the beam in the horizontal direction and diverge the beam in the vertical direction, and the quadrupole electromagnet 7 modulates the orbit gradient so as to diverge the beam in the horizontal direction and converge the beam in the vertical direction. It works to change. By the action of these quadrupole electromagnets, the beam circulates around the design trajectory 1 with betatron oscillation, and the frequency of the betatron oscillation depends on the excitation amount of the converging quadrupole electromagnet 5 and the diverging quadrupole electromagnet 7. Can control. In order to stably circulate the beam during the injection and acceleration processes, the betatron frequency (tune) for one revolution of the accelerator must be set to a value that does not cause resonance, especially, away from the tune that causes low-order resonance. Need to be kept. In this embodiment, the quadrupole electromagnets 5 and 7 are adjusted so that the horizontal tune νx is 1.73 and the vertical tune νy is 1.23. In this state, the beam circulates stably in the accelerator, and energy is given from the high-frequency acceleration cavity 8 in the process. The frequency f of the high frequency applied to the high frequency accelerating cavity is set to an integral multiple (n times) of the frequency at which the beam goes around. The beam circulates in the circling direction, that is, in the s direction, in n lumps (bunch shape) so as to synchronize with the high frequency. While applying energy to the beam from the high-frequency accelerating cavity 8, the magnetic field intensity is increased while maintaining the magnetic field intensity ratio between the bending electromagnet 3 and the quadrupole electromagnets 5, 7 constant.
Then, in the curved portion of the bending electromagnet, an increase in centrifugal force due to an increase in the beam energy and an increase in the centripetal force due to an increase in the amount of excitation of the bending electromagnet balance and orbit around the same orbit. FIG. 3 shows a trajectory in the phase space (x, dx / ds) at the emission position s = so in the s direction in this process. The trajectory in the phase space in FIG. 3 appears to have many similar ellipses with different diameters, but the diameter of the ellipse corresponds to the magnitude of the betatron oscillation amplitude, and the diameter of the ellipse is small. The smaller the betatron oscillation amplitude is, the smaller the betatron oscillation amplitude is.

FIG. 4 shows an operation method in the process of emitting light after accelerating to the target energy. First, as shown in FIG. 4A, the application of energy to the beam from the high-frequency acceleration cavity 8 is stopped. Thereby, the beam changes from a bunch shape to a continuous beam. Next, in FIG. 4 (2), the power of the converging quadrupole electromagnet 5 and the power of the diverging quadrupole electromagnet 7 are adjusted to set the horizontal tune νx to 1.67. Next, as shown in FIG. 4C, a current for resonance excitation is supplied to the hexapole electromagnet 9. The current flowing through the hexapole electromagnet 9 is set to a value such that particles having a large betatron oscillation amplitude of the circulating beam fall within the stability limit, and the value is obtained in advance by calculation or by repeating the emission operation. At this time, the phase space at the position of the output deflector 13 is as shown in FIG. 5, and the trajectory in the phase space is triangular. Next, as shown in FIG. 4D, an irregular time-varying signal is applied to the beam by the high-frequency application device 14 of the circular accelerator in FIG. FIG.
2 shows a configuration of the high-frequency applying device 14. Electrode 2 of FIG.
Numerals 5 and 26 are rod-shaped electrodes which are arranged so as to face each other in the horizontal direction, and a magnetic field and an electric field in the direction shown in FIG. The load resistor 23 in FIG. 7 is installed so that the applied current does not reflect from the electrode end to the power supply side. The orbital gradient of the beam changes due to the effects of electric and magnetic fields, and the betatron oscillation amplitude of the beam in the phase space shown in FIG. 5 begins to increase. Particles exceeding the stability limit shown in FIG. The amplitude sharply increases and the light is emitted from the emission deflector 13. Thereafter, when an irregular signal is applied to the electrodes 25 and 26, the betatron oscillation amplitude of each particle increases, and the particles having an initial small betatron oscillation amplitude soon exceed the stability limit of FIG. 5 and are emitted from the emission deflector 13. You. The stability limit is constant in the phase space of FIG. 5, and the orbit gradient dx / ds and the turn separation Ts of the output beam are also kept constant during the output process. Here, an electrode as shown in FIG. 7 was used. However, a time-varying component is superimposed on a power supply current of one of the electromagnets constituting the accelerator, or a new component is set within the stability limit of resonance at the time of emission. By providing a dedicated electromagnet for increasing the betatron oscillation of the particles and changing the power supply current irregularly, the same emission as described above can be performed.

In the above embodiment, the tune of the beam having an extremely small betatron oscillation amplitude is 1.67 set by a quadrupole electromagnet. However, due to the effect of the multipole electromagnet for generating resonance, the beta tune near the stability limit is obtained. The tune of particles with large thoron oscillation amplitude is 1.67-1.6666 from this value.
The tune of the beam, with a deviation of about 0.003 and an oscillation amplitude between them, is continuously distributed between 1.6666 and 1.67. On the other hand, as described in the operation section, in order to increase the betatron oscillation amplitude of the beam, it is desirable to apply an electromagnetic field having a frequency component approximately equal to the tune distribution of the beam to the beam. Therefore, the irregular signal power supply 24 of FIG. 7 may be a noise having an extremely wide frequency spectrum or a frequency band whose frequency is about 0.6 of the revolving frequency.
The frequency spectrum may be in the range of 5 to 0.70 times, or may be a frequency spectrum obtained by adding a frequency in the above range to an integral multiple of the circulating frequency . FIG. 8 shows a configuration example of the irregular signal power supply. As shown in FIG. 8, after passing a frequency component from 0 to 0.025 times the circulating frequency from a noise source 51 having an almost infinite frequency spectrum through a filter 52, the noise source 51 has a frequency of 0.675 times the circulating frequency of the beam. When the signal is generated by the local oscillator 53 and the product of the signal and the output signal of the filter 52 is obtained by the multiplier 54, an irregular signal having a spectrum from 0.65 to 0.7 times the revolving frequency can be produced. Alternatively, a high-frequency source having a required frequency spectrum can be produced by changing the pass frequency of the filter 52 without using the local oscillator 53. Further, in this embodiment, an irregular signal is used as a disturbance to the beam, and the beam is diffused in the phase space, so that the beam can be emitted with a constant current without being affected by the current ripple of the electromagnet power supply.

Next, a second embodiment of the present invention will be described.
The second embodiment has the same equipment configuration as the first embodiment except that the signals applied to the electrodes are made regular, and the operating method at the time of emission is also the same as that of FIG. As shown in FIG.
A single frequency signal source 55 shown in FIG. 9 is used in place of the irregular signal power supply 24 of FIG. The frequency f is a frequency Frev at which the beam circulates, and a fraction 0.33 (= 1-0.6) of the tune at the time of emission.
7) is equal to the product of When a signal of such a frequency is applied, the period of the external signal applied from the electrode and the period of the betatron oscillation substantially coincide with each other. Therefore, even for particles within the stability limit of FIG. Then, the light is emitted in the same manner as in the first embodiment. As described above, when an AC signal having a single frequency is applied, particles having a tune synchronized with this frequency are resonated by an external signal, and as a result, the vibration amplitude is rapidly increased and emission can be performed in a short time. . However, many particles that do not resonate with an external signal are emitted later than the resonance particles.

In the above embodiment, the single-frequency disturbance shown in FIG. 9 is used. However, a plurality of single-frequency signal sources 55 shown in FIG. 10 are used, and a plurality of frequencies f1, f2,.
When the signal of n is added to the electrodes 25 and 26 through the adder 56, it becomes easier to emit a beam having a tune width as compared with a case where a single-frequency disturbance is used. In this case, the frequency of the signal to be applied is desirably set to a value close to a tune having a distribution.

In the first and second embodiments, 25 and 26 in FIG.
By applying signals of opposite polarities to both electrodes using the two electrodes shown in (1), an electromagnetic field was added to the beam, and the orbital gradient was changed. On the other hand, when the same electrode is used and a signal of the same polarity is applied to the two electrodes, an electric field in the s direction is generated at the ends of the electrodes 25 and 26 in the s direction, the beam is accelerated or decelerated, and the orbit gradient of the beam changes. Therefore, the betatron oscillation amplitude of the beam increases. At this time, the structure of the electrode may be not only a rod shape but also a plate shape. When signals of opposite polarities are applied to both electrodes, an electric field in the x direction or y direction can be generated by using a small disc-shaped electrode. Generally, when a time-varying signal is externally applied to the metal electrode, an electromagnetic field is generated and the orbit gradient of the beam can be changed, so that the betatron oscillation amplitude of the beam can be increased.

Next, a third embodiment of the present invention will be described.
FIG. 11 shows the device configuration of the third embodiment. 1 in that the octupole electromagnet 30 is used as a multipole electromagnet for exciting a secondary resonance (half-integer resonance) for emission, and that the betatron oscillation amplitude is within the stability limit of resonance. Is to use the high-frequency application cavity 31 to increase the number. However, the high-frequency application cavity 31 uses a cavity different from the high-frequency acceleration cavity 8 for accelerating the beam from low energy to high energy. FIG. 12 shows an operation method after accelerating the beam to a predetermined energy for the third embodiment. After the acceleration is completed, the high-frequency accelerating cavity 8 is stopped in FIG. 12A, the convergence quadrupole electromagnet 5 and the divergence quadrupole electromagnet 7 are adjusted in FIG. 12B, and the horizontal tune νx is set to 1.55. Approach. Thereafter, the octupole electromagnet 30 is excited. The magnetic field strength of the octupole electromagnet is set such that the particles circulate stably while undergoing betatron oscillation with different amplitudes. Here, a signal that changes irregularly with time is applied to the high-frequency application cavity 31. This high frequency application cavity 31
Is a cavity in which an electric field is generated in the circling (s) direction of the beam and a magnetic field is generated in the vertical (y) direction, as shown in FIG. 13, in which the orbital gradient of the beam is irregular at each circling. The particles are changed and the initial betatron oscillation amplitude is sequentially emitted from the emission deflector 13 after exceeding the stability limit from a large particle. By continuing to apply a signal that changes irregularly to the high-frequency application cavity 31, the amplitude of the particles whose initial betatron oscillation amplitude is small increases by the same operation as in the first embodiment, and the particles exceed the stability limit. Is done.

Next, a fourth embodiment of the present invention will be described. The fourth embodiment relates to a method for adjusting the beam position and the beam current during the emission. FIG. 14 shows the device configuration of the fourth embodiment. In addition to the device configuration of the first embodiment shown in FIG. 1, an electromagnet 35 for correcting the trajectory of the emitted beam, a beam position measuring device 32, a current measuring device 33, and a control computer 34 are provided. FIG. 15 shows an operation method using this device configuration. In the present embodiment, according to the pattern stored in advance in the control computer 34 shown in FIG.
The intensity of an irregular time-varying signal applied to the high-frequency applying device 14 is controlled. The signal intensity pattern to be stored in the control computer 34 is determined for each operation, assuming that the operation after the beam is incident and accelerated on the circular accelerator and then emitted is one operation. Fig. 4 shows the operation method of incidence, acceleration, and emission.
It is the same as the driving method. The intensity pattern of the signal to be applied to the high-frequency application device 14 includes the time change of the target beam position and the beam current stored in advance in the computer and the beam position measured by the beam position measurement device 32 and the beam current measurement device 33. And the difference from the beam current is minimized. The target beam current can be easily realized not only in a temporally constant pattern but also in a pattern in which current emission and stop are repeated by using and stopping the means for increasing the betatron oscillation amplitude.

[0050] In this embodiment, by using the beam measuring device by changing the high-frequency signal intensity pattern so as to obtain the desired properties, even without the use of a beam measuring device, the signal applied to the RF knockout electrode 14 By increasing the intensity of the beam during the emission, it is possible to emit a temporally constant beam current.
This is because, in the early stage of emission, there are many particles with large betatron oscillation amplitude that can be emitted with a small intensity signal, but in the late stage of emission, the number of orbiting particles decreases, and in order to obtain a constant emission current This is because it is necessary to increase the increasing speed of the betatron oscillation amplitude of the beam. Therefore, if such a time-varying high-frequency signal intensity pattern is given in advance, the target pattern can be realized in a shorter time in the operation of FIG.

In this embodiment, in order to obtain a target beam characteristic, only the intensity of the signal applied to the high-frequency application device 14 is adjusted. However, the frequency and the frequency spectrum of the high-frequency signal are adjusted. Adjustment of the size of the resonance stability limit, that is, adjustment of tune by a quadrupole electromagnet, adjustment of the strength of the multipole electromagnet 9 for resonance excitation, or other electromagnets, such as the bending electromagnet 3 and the orbit correction electromagnet 35, etc. Similar adjustments can be made when used.

In the above embodiment, the control of the output beam during normal operation is explained. Next, referring to FIG. 16, a description will be given of an operation method during an emergency stop during output according to a fifth embodiment. FIG.
Up to (5) is a normal operation, which is the same as the operation method of FIG. In FIG. 16 (6), it is determined whether there is a stop signal from the beam use system or an emergency stop signal from various safety systems. If there is a stop signal, the high frequency signal for increasing the beam system is stopped, and the beam is emitted. To stop. Since the high-frequency signal for beam emission can be stopped in a few microseconds, the beam emission can be stopped reliably in a short time. Further, if the stop of this high-frequency signal and the orbit change by the electromagnet of the output beam transport system are used simultaneously, it will be more reliable Beam can be stopped. Further, even if the beam emission is stopped halfway, the beam remaining in the accelerator can be emitted by applying the irregular signal for emission again. FIG. 16 shows a case where an irregular signal is applied for emission, but the same applies to a case where an AC signal having a single or a plurality of frequencies is applied.

Next, a sixth embodiment will be described with reference to FIG. In the sixth embodiment, neutral particles collide with the orbital beam to increase the betatron oscillation amplitude of particles within the stability limit of resonance. In the embodiment shown in FIG. 1, the high-frequency application device 14 is used to apply a time-varying electromagnetic field to the beam, but in this embodiment, a neutral particle injection device 36 is used instead of the high-frequency application device 14. FIG. 18 shows an operation method in this embodiment. The operation method is the same as that of FIG. 4 except for the part of (4) of FIG. 18 where neutral particles are injected. Neutral particle collisions can gradually increase the betatron oscillation amplitude of the orbiting beam, so that the beam position, beam diameter, and turn separation are all constant while maintaining the stability limit of resonance constant. it can. The emission current can be adjusted by adjusting the injection amount of the neutral particles.

Next, a seventh embodiment will be described. In the seventh embodiment, a charged particle different from the orbiting beam is made to collide with the orbiting beam to increase the betatron oscillation amplitude of the particle within the stability limit of resonance. In the sixth embodiment shown in FIG. 17, the neutral particle implanter 36 is used, but in this embodiment, an ion injector whose cross section is shown in FIG. 19 is used instead. Ions emitted from the ion source are implanted horizontally into the orbiting beam region. The ion implantation from this ion source is performed in place of the neutral particle implantation of the operation method shown in FIG. 18, but the same characteristics as those of the other embodiments described above can be realized with respect to beam emission. Further, the same emission can be realized even if a thin film is provided in a region where gas or ions are implanted and a charged particle beam is collided.

Hereinafter, the effects of the present invention will be shown by simulation. The simulation conditions were as follows: protons were used as charged particles, and the final energy during orbit was 300 M
eV, the resonance to be used is the secondary resonance shown in the third embodiment. The position of the electrode of the output deflector is 60 mm in the horizontal direction. FIGS. 20 and 21 show a conventional operation method in which the amplitude of the betatron vibration before resonance is 10 mm and 3 mm.
The phase space is shown when the deviation from 1/2 of the tune is set to 0.01 with respect to the proton of mm, and the deviation is changed from 0.01 to 0.001 for resonance. The stability limit of the secondary resonance has an elliptical shape unlike the tertiary resonance. On the other hand, FIG.
2 and 23 are diagrams showing the operation method of the present invention. FIG.
Is to adjust the deviation of tune from 1/2 to 0.01 for protons whose betatron oscillation amplitude before resonance is 3 mm, and to resonate them. 3 shows a phase space when the amplitude is gradually increased. FIG. 23 shows the phase space when the state of FIG. 22 is further advanced and protons exceeding the stability limit (about 10 mm) are being emitted. In the conventional operation method, when the betatron oscillation amplitude before resonance is 10 mm and 3 mm, the turn separation Ts is about 10 mm and about 1 mm, respectively. Therefore, in the prior art, the betatron oscillation amplitude is 3 mm.
Protons collide with the electrode and can hardly be emitted. In addition, the deviation of the tune from 1/2 is 0.0.
Emission gradient is 7m because it is adjusted from 1 to 0.001
rad also changes. On the other hand, in the present invention, even when the betatron oscillation amplitude before resonance is 3 mm, the betatron oscillation amplitude gradually increases and reaches about 10 mm, causing resonance, and is emitted with a turn separation Ts of 10 mm as in FIG.
The difference in the orbital gradient at the position of the deflector for emission between the case where the initial betatron vibration amplitude is smaller than 3 mm and the case where the initial vibration amplitude is 10 mm is 0.01 mra.
d or less, and the emittance of the output beam is 1π mm · mra
d or less. In this manner, a beam having a small initial betatron oscillation amplitude of 10 mm or less can be emitted similarly to the case of 10 mm. In the present invention, since the tune and the turn separation Ts can be made constant, the emission gradient, the emission position, and the beam diameter can be made constant. Furthermore, since the beam distribution often has a smaller betatron oscillation amplitude, it is not possible to obtain an emission efficiency of 50% with the conventional operating method, whereas the operating efficiency of the present invention is to increase the emission efficiency to 90% or more. be able to.

Finally, an embodiment of the medical accelerator system of the present invention will be described with reference to FIG. In the present embodiment, the beam from the pre-accelerator 16 is converted by the injector 15 into a circular accelerator 10.
Incident at 1. The configuration of the circular accelerator 101 and the method of emitting a beam are the same as those of the first embodiment shown in FIG. 1. After the beam is incident from the pre-stage accelerator 16, the beam is accelerated to a desired energy in 0.5 seconds, and A long pulsed beam is emitted over seconds. In the next 0.5 seconds, the amount of excitation of the electromagnet is reduced to prepare for the next incidence and acceleration. In this manner, the incidence, acceleration, and emission of the beam are repeated every two seconds.
At the time of emission, the stability limit of resonance is kept constant, and the emission frequency of the betatron is increased by the emission high-frequency application device 14 to generate resonance in the beam. Since the stability limit of the resonance is constant, the orbit gradient and turn separation at the position of the deflector for emission are constant, and the light can be emitted with a constant emission efficiency over time, and an emission efficiency of 90% or more can be obtained. The beam emitted from the emission deflector 13 is transported by the beam transport system 102 to a plurality of treatment rooms 103 respectively installed in the irradiation device . The transport system 102 is provided with a transport system electromagnet 104 for adjusting the beam diameter and the orbit gradient. The emittance of the transported beam is shown in FIG.
As described using 0 and 23, it is 1πmm · mrad or less. The size of the beam is obtained from twice the product of the emittance and a quantity called a betatron function, which is 1/2. The betatron function varies depending on the position of the beam transport system, but can be suppressed to 20 m or less by adjusting the amount of excitation of the transport system electromagnet 104, so that the maximum beam size in the transport system is about 10 mm. Therefore, the diameter of the vacuum duct used for the transport system 102 can be reduced to 20 mm or less even with a margin. The transport switching of the output beam to the plurality of treatment rooms is performed using the beam switching electromagnet 105. The switching of the beam is repeatedly performed in the beam emission process, that is, in a short time within 1 second. Thus, the beam is repeatedly distributed to a plurality of treatment rooms during one extraction. Of course, it is also possible to transport the beam to only one treatment room during one extraction, and to switch the beam to the next treatment room at the next extraction. Size of the beam to be irradiated to the patient is irradiated target in the treatment room, although adjustment such as position performed using the irradiation beam adjustment electromagnet irradiation device (not shown), emittance of the emitted beam is emitted method of the present invention 1πmm -Since it is constant at mrad or less, the change in size and position of the beam irradiated to the patient can be suppressed to 3 mm or less.

[0057]

According to the circular accelerator of the first aspect, the resonance of
Orbiting the orbit stably inside the stability limit
The charged particle beam is controlled by the
Therefore, the betatron oscillation amplitude is increased and the resonance stability limit
Move out of the field and take it out of the exit deflector
You. Betatron oscillations within the stability limits of such resonances
Increasing the amplitude improves the extraction efficiency of the charged particle beam
You. As a result, the current value of the emitted charged particle beam is large.
It will be good. Circular accelerator according to claims 3, 5 and 7, and claim
The operation method of the eleventh circular accelerator has the same effect. Contract
According to the operation method of the circular accelerator according to claim 2, the quadrupole magnet
Substantially constant excitation and resonance excitation electromagnet
And the strength of the magnetic field created by each electromagnet becomes substantially constant,
The stability limit of resonance can be made substantially constant. As a result,
Of the charged particle beam incident between the electrodes of the projectile deflector
The angle and displacement increase are substantially constant and the diameter is substantially
A constant charged particle beam can be extracted. Also,
The emission position of the charged particle beam can also be made substantially constant. Contract
The effect of the circular accelerator of claim 1 also occurs. The circular shape of claim 12.
The operation method of the accelerator has the same effect.

According to the circular accelerator of the fourth aspect, the irregular signal
Since the power supply is provided,
Generates a time-varying magnetic field using an irregular signal
Can be Therefore, the current ripple of other power supplies
The effect can be eliminated and a charged particle beam with a substantially constant current
Can be emitted. The circular accelerator according to claims 6 and 8 has the same effect.
Have.

According to the circular accelerator of claim 9, the charged particles
Includes frequency components synchronized to the betatron oscillation of the beam
By using high-frequency signals, the
And the betatron oscillation amplitude of the charged particle beam increases rapidly.
Add. Therefore, a charged particle beam within the stability limit of resonance
It can move out of the resonance stability limit in a short time and charged particles in a short time
A child beam can be emitted.

According to the circular accelerator of the tenth aspect, the high frequency
By controlling the signal strength, the charged particle beam
The rate of increase in betatron oscillation amplitude can be controlled. this
Is a charged particle beam moving from inside to outside the stability limit of resonance.
Control the number of charged particles
The current value of the system can be adjusted. Claims 13 and 14
The operation method of the circular accelerator has the same effect. Claim
According to the operation method of the 15 circular accelerators, the charged particle beam
High frequency applied to the charged particle beam during
Increasing the strength of the wave signal increases the commonality during beam extraction.
The number of charged particles moving from inside to outside of the sound stability limit
Can be constant. Therefore, during that time,
To make the current of the charged particle beam substantially constant.
it can.

According to the medical system of the sixteenth aspect, the medical system
The light is emitted by the same operation and effect as the circular accelerator in item 1.
The current value of the charged particle beam is large,
Since it is emitted efficiently, a charged particle beam with a large current value
It can be used efficiently for medical treatment. The medical treatment of claim 17.
According to the system, the charged particle beam is delivered to multiple treatment rooms.
Since it can be used separately, charged particles with large current value
The child beam can be used more efficiently for medical treatment.

[Brief description of the drawings]

FIG. 1 is a diagram showing a circular accelerator according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a stability limit in a phase space.

FIG. 3 is a diagram showing a phase space at the time of beam incidence / acceleration.

FIG. 4 is a diagram showing an operation method at the time of emission according to the first embodiment.

FIG. 5 is a diagram showing a phase space immediately before emission according to the first embodiment.

FIG. 6 is a diagram showing an output deflector electrode of the first embodiment.

FIG. 7 is a diagram illustrating a configuration of a high-frequency application device according to the first embodiment.

8 is a diagram showing a configuration example of the irregular signal power supply of FIG. 7;

FIG. 9 is a diagram illustrating a configuration example of a single frequency signal source according to a second embodiment.

FIG. 10 is a diagram illustrating a configuration example of a multi-frequency signal source according to a second embodiment.

FIG. 11 is a diagram illustrating an accelerator according to a third embodiment.

FIG. 12 is a diagram illustrating an operation method according to a third embodiment.

FIG. 13 is a diagram illustrating a high-frequency application cavity according to a third embodiment.

FIG. 14 is a diagram illustrating an accelerator according to a fourth embodiment.

FIG. 15 is a diagram showing an operation method according to a fourth embodiment.

FIG. 16 is a diagram showing an operation method according to a fifth embodiment.

FIG. 17 is a diagram illustrating an accelerator according to a sixth embodiment.

FIG. 18 is a diagram showing an operation method according to a sixth embodiment.

FIG. 19 is a view showing an ion injector of a seventh embodiment.

FIG. 20 is a diagram showing a phase space when protons having a betatron oscillation amplitude of 10 mm before resonance are resonated by a conventional operation method.

FIG. 21 is a diagram showing a phase space when protons having a betatron oscillation amplitude of 3 mm before resonance are resonated by a conventional operation method.

FIG. 22 is a diagram showing a phase space when a proton having a betatron oscillation amplitude before resonance of 3 mm is resonated by the operating method of the present invention.

FIG. 23: The state of FIG. 22 advances, and the stability limit (about 10 mm)
FIG. 7 is a diagram showing a phase space when protons exceeding the number are emitted.

FIG. 24 is a diagram showing a configuration example of a medical accelerator system of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Design track | truck, 3 ... Bending electromagnet, 5 ... Quadrupole electromagnet for convergence, 7 ... Quadrupole electromagnet for divergence, 8 ... High frequency acceleration cavity, 9 ...
Electromagnet for resonance excitation, 13 ... Deflector for emission, 14 ...
High frequency applying device, 15: injector, 20: deflector electrode for emission, 22: vacuum duct, 23: load resistance, 24:
Power supply, 25: rod-shaped electrode, 26: rod-shaped electrode, 31: high-frequency application cavity, 32: position measuring device, 33: current measuring device,
34 computer, 50 amplifier, 51 noise source, 52 filter, 53 local oscillator, 54 multiplier, 55 single frequency signal source, 56 adder.

Claims (18)

(57) [Claims] Means for orbiting a charged particle beam along a circular orbit, means for causing a betatron oscillation of said charged particle beam to resonate outside a stability limit of resonance, and moving said charged particle beam from said circular orbit. In a circular accelerator having an extraction deflector for taking out, a betatron oscillation amplitude of a charged particle beam within the stability limit of the resonance is increased, and a charged particle beam within the stability limit of the resonance is moved out of the stability limit of the resonance. A circular accelerator having a betatron oscillation amplitude increasing means for causing the vibration to increase. 2. A deflection electromagnet, a quadrupole electromagnet, and a high-frequency accelerating cavity provided along the orbit of the charged particle beam, and a resonance that brings the betatron oscillation of the charged particle beam into a resonance state outside the resonance stability limit. In a circular accelerator having an excitation electromagnet and an emission deflector for taking out the charged particle beam from the orbit, in taking out the charged particle beam, in order to make the stability limit of the resonance substantially constant, Control means for controlling the amount of excitation of the quadrupole electromagnet and control means for controlling the amount of excitation of the electromagnet for resonance excitation; and increasing the betatron oscillation amplitude of the charged particle beam within the stability limit of the resonance to increase the resonance of the resonance. A betatron oscillation amplitude increasing means for moving a charged particle beam within the stability limit outside the stability limit of the resonance. Speed gear. 3. The betatron oscillation amplitude increasing means is provided along the orbit of the charged particle beam and generates a time-varying magnetic field.
Circular accelerator. 4. The means for generating a time-varying magnetic field includes: an irregular signal power supply for generating a signal with an irregular time change; and the magnetic field by applying the signal with an irregular time change. Means for generating a circular accelerator. 5. The betatron oscillation amplitude increasing means is provided along the orbit of the charged particle beam and generates a time-varying electric field.
Circular accelerator. 6. The means for generating a time-varying electric field includes: an irregular signal power supply for generating a signal having an irregular time change; and an electric signal generating means for generating the electric field by applying the signal having an irregular time change. circular accelerator of claim 5 including means for generating a. 7. The circular accelerator according to claim 1, wherein said betatron oscillation amplitude increasing means is a high frequency applying means for increasing a betatron oscillation amplitude of said charged particle beam by applying a high frequency signal. 8. The circular accelerator according to claim 7, wherein said high-frequency signal is a high-frequency signal whose time variation is irregular. 9. The circular accelerator according to claim 7, wherein said high-frequency signal is a high-frequency signal including a frequency component synchronized with a betatron oscillation of said charged particle beam. 10. The betatron oscillation amplitude increasing means,
8. A device according to claim 7, further comprising means for controlling the intensity of said high-frequency signal.
Circular accelerator. 11. A charged particle beam that orbits a charged particle beam along a circular orbit to bring a betatron oscillation of the charged particle beam into a resonance state outside the stability limit of resonance, and the resonance state of the charged particle beam passes through an output deflector. In the method of operating a circular accelerator for taking out the orbit from the orbit, when taking out the charged particle beam, the betatron oscillation amplitude of the charged particle beam within the stability limit of the resonance is increased, and the charge within the stability limit of the resonance is increased. A method for operating a circular accelerator, comprising moving a particle beam outside the stability limit of the resonance. 12. The method according to claim 11, wherein the increase in the amplitude of the betatron oscillation of the charged particle beam within the stability limit of the resonance is performed while the stability limit of the resonance is kept substantially constant. 13. The method for operating a circular accelerator according to claim 11, wherein the increasing speed of the betatron oscillation amplitude of the charged particle beam within the stability limit of the resonance is changed. 14. A claim for varying the intensity of the high frequency signal applied to the RF mark pressurizing means betatron provided along said orbit to increase the oscillation amplitude of the charged particle beam in said stability limit of resonance Item 13. The method for operating a circular accelerator according to item 11 or 12. 15. The method according to claim 14, wherein the intensity of the high-frequency signal is increased during the extraction of the charged particle beam. 16. A means for orbiting a charged particle beam along a circular orbit, means for causing a betatron oscillation of said charged particle beam to resonate outside a stability limit of resonance, and a step of moving said charged particle beam from said circular orbit. A medical system comprising: a circular accelerator having an extraction deflector for extraction; and a beam transport system for transporting the charged particle beam having passed through the emission deflector to a treatment room, wherein a beta of the charged particle beam within a stable limit of resonance is provided. A medical system comprising: a betatron oscillation amplitude increasing means for increasing a thoron oscillation amplitude to move a charged particle beam within the stability limit of the resonance out of the stability limit of the resonance. 17. A beam transport system comprising: a main beam transport duct connected to the exit deflector; a plurality of branch beam transport ducts each connected to the beam transport duct and led to a different one of the treatment rooms; 17. The medical system according to claim 16 , further comprising a switching unit configured to switch transport of the charged particle beam from a beam transport duct to each of the branch beam transport ducts. 18. The medical system according to claim 17 , further comprising a beam irradiation device provided in the treatment room, for irradiating the irradiation target with the charged particle beam guided by the branch beam transport duct.