TW201826889A - High-frequency acceleration device in circular accelerator and circular accelerator - Google Patents

Abstract

An object of the present invention is to drastically change the adjustable band of resonance frequency which changes in accordance with electrostatic capacity adjustable range, without narrowing the band. A high-frequency (2) in a circular accelerator according to the present invention includes: a transmission line (8) having an inner conductor (17) and an outer conductor (16) surrounding the inner conductor (17), and transmitting high-frequency power to electrodes (6, 7); and a capacitive-variable reactance element (11) and a frequency adjusting mechanism (43) for changing the resonance frequency of an acceleration cavity (42). The frequency adjusting mechanism (43) includes: an adjusting mechanism inner conductor (12) connected to the inner conductor (17) of the transmission line (8) and extending in a direction away from the inner conductor (17), an adjusting mechanism outer conductor (14) connected to the outer conductor (16) of the transmission line (8) and containing the adjusting mechanism inner conductor (12), and a movable short plate (13) composed of a conductor, electrically connected to the adjusting mechanism inner conductor (12) and the adjusting mechanism outer conductor (14), and arranged so as to allow the connection position between it and the adjusting mechanism inner conductor (12) and the adjusting mechanism outer conductor (14) to be changed.

Description

High-frequency acceleration device for circular accelerator and circular accelerator

The present invention relates to the field of a circular accelerator for particle beam therapy, and more particularly to a high frequency acceleration device for accelerating charged particles by a plurality of energies by a resonance frequency change in a synchro cyclotron. .

A synchrocyclotron is a circular accelerator that is in the gap between the poles belonging to the gap of the opposite poles of the electromagnet, and accelerates the charged particles to a high energy by rotating the charged particles in a manner of drawing a spiral orbit. Round accelerator. The charged particles are incident from the center of the synchrocyclotron to the magnetic pole pitch, and are wound in a magnetic pole pitch by a magnetic field formed by biasing the electromagnet and the magnetic pole. The high-frequency acceleration device generates an electric field to the charged particles by forming an electric field in the electrode portion in synchronization with the winding frequency of the charged particles. The winding frequency of the charged particles decreases as the energy increases. Therefore, in order to reduce the frequency of the electric field formed in the electrode portion and the winding frequency of the charged particles, it is necessary to make the resonance frequency of the high-frequency acceleration device that supplies electric power to the electrode portion. Decreased as the charged particles accelerate. The winding frequency of the charged particles is determined according to the emission energy emitted from the synchrocyclotron and the magnetic field distribution of the electromagnet of the synchrocyclotron.

The resonance frequency of the high-frequency acceleration device is determined in accordance with the capacitance and inductance of the high-frequency acceleration device. The high-frequency acceleration device is configured by, for example, a D-type electrode that belongs to an electrode portion that forms an electric field, a transmission line that transmits power to the D-type electrode, and a rotating capacitor that changes a resonance frequency. Patent Document 1 discloses an RF structure corresponding to a high-frequency acceleration device that applies a high-frequency (RF) voltage to a D-type electrode of a synchrocyclotron. The high-frequency acceleration device of Patent Document 1 includes two variable reactance elements (variable capacitive reactance elements) for adjusting a resonance frequency. The first variable reactance element is a rotating capacitor, and the second variable reactance element is a capacitor formed by an inner conductor and a plate facing the inner conductor. The plate partially changes the distance between the inner conductor and the outer conductor of the high-frequency acceleration device to adjust the electrostatic capacitance. As described above, in the high-frequency acceleration device of Patent Document 1, in order to change the resonance frequency band by the rotation of the capacitor, an electrode plate for adjusting the capacitance of the high-frequency acceleration device is used.

Patent Document 2 discloses a resonance frequency adjustment mechanism for preventing an increase in electrostatic capacitance of a D-type electrode and a resonance cavity (acceleration cavity) in a cyclotron belonging to a circular accelerator. The invention includes a bonded capacitor body opposite to the D-type electrode, an inner conductor connected to the combined capacitor body, an outer conductor surrounding the D-type electrode and the inner conductor, and a short slidably disposed between the inner conductor and the outer conductor Road board. The resonance frequency adjustment mechanism of Patent Document 2 adjusts the inductance of the capacitance connected in series with the capacitance of the junction capacitor body and the D-type electrode by changing the position of the short-circuit plate to adjust the resonance frequency of the resonance circuit.

[Previous Technical Literature] [Patent Literature]

Patent Document 1: Japanese Laid-Open Patent Publication No. 2015-532509 (paragraphs 0135 to 0138, paragraph 27)

Patent Document 2: Japanese Laid-Open Patent Publication No. Hei 11-354299 (paragraphs 0033 to 0036, and FIG. 11)

In a synchrocyclotron for particle beam therapy, in order to extract a charged particle beam suitable for the energy of a treatment site, it is necessary to change the energy of the emitted beam emitted from the synchrocyclotron. When the energy of the outgoing beam emitted from the synchrocyclotron is to be changed, the resonance frequency must be greatly changed. In the high-frequency acceleration device of Patent Document 1, when the capacitance of the output beam is to be increased, the capacitance of the electrostatic capacitance is increased by the rotation of the rotating capacitor, and the amplitude of the electrostatic capacitance is relatively small. The frequency adjustment range of the high-frequency acceleration device is narrowed. As a result, it will be difficult to amplify the energy change range of the outgoing beam. In other words, in the synchrocyclotron having the high-frequency acceleration device of Patent Document 1, it is difficult to take out a charged particle beam suitable for energy such as a treatment site having a large depth range from the skin.

Further, in the resonance frequency adjusting mechanism of Patent Document 2, since the coupling capacitor body facing the D-type electrode of the cyclotron is provided in the resonance cavity (acceleration cavity), the cyclotron of Patent Document 2 is configured to be connected to the capacitor body. The inner conductor penetrates in a direction perpendicular to the orbital surface of the magnetic pole and the yoke surrounding the resonant cavity (acceleration cavity). Therefore, in the cyclotron of Patent Document 2, there is a problem that the shape of the magnetic pole and the yoke which form a magnetic field in the resonant cavity (acceleration cavity) becomes complicated. When the resonance frequency adjustment mechanism of Patent Document 2 is applied to a synchrocyclotron, there is a problem that the shape of the magnetic pole and the yoke which form a magnetic field in the resonance cavity (acceleration cavity) becomes complicated.

An object of the present invention is to obtain a high-frequency acceleration device that can change a tuning band of a resonance frequency that changes in accordance with a capacitance adjustment range to a wide-band circular accelerator without complicating the shape of the magnetic pole and the yoke.

The high-frequency acceleration device of the circular accelerator of the present invention is a method in which a high-frequency electric field is applied to charged particles which are spirally orbited by a bias magnetic field formed by a biasing electromagnet of a circular accelerator, and the charged particles are accelerated. A high-frequency acceleration device for a circular accelerator. The high-frequency acceleration device of the circular accelerator includes: an electrode that applies a high-frequency electric field to the charged particles; and a transmission line that has an inner conductor and an outer conductor surrounding the inner conductor, and transmits high-frequency power to the electrode; The transmission line and the electrode are configured; and the variable capacitance reactance element and the frequency adjustment mechanism change the resonance frequency of the acceleration cavity. Frequency of high-frequency acceleration device of circular accelerator The adjusting mechanism comprises: an inner conductor of the adjusting mechanism, which is connected to the inner conductor of the transmission line, and extends away from the inner conductor; the outer conductor of the adjusting mechanism is connected to the outer conductor of the transmission line, and encloses the inner conductor of the adjusting mechanism The movable short-circuiting plate is composed of a conductor, and is electrically connected to the inner conductor of the adjusting mechanism and the outer conductor of the adjusting mechanism, and is arranged to change the connection position with the inner conductor of the adjusting mechanism and the outer conductor of the adjusting mechanism.

The high-frequency acceleration device of the circular accelerator of the present invention includes a variable capacitive reactance element and a frequency adjustment mechanism that change the resonance frequency of the acceleration cavity, and the internal conduction system of the adjustment mechanism of the frequency adjustment mechanism is connected to the inner conductor of the transmission line, and The movable short-circuiting plate of the frequency adjusting mechanism is electrically connected to the inner conductor of the adjusting mechanism and the outer conductor of the adjusting mechanism, and is arranged to change the connection position with the inner conductor of the adjusting mechanism and the outer conductor of the adjusting mechanism. The adjustment band of the resonance frequency that changes according to the capacitance adjustment range is drastically changed without narrowing the band.

1‧‧‧Synchronous cyclotron (circular accelerator)

2‧‧‧High frequency acceleration device

3a, 3b‧‧‧Electrical coil

4a, 4b‧‧‧ yoke

5‧‧‧Ion source

6‧‧‧D type electrode (electrode)

7‧‧‧Dummy D-type electrode (electrode)

8‧‧‧Transmission line

9‧‧‧Input port

10‧‧‧Input coupler

11‧‧‧Rotating Capacitor (Variable Capacitive Reactive Component)

12‧‧‧Adjusting the inner conductor of the mechanism

13‧‧‧ movable short circuit board

14‧‧‧Adjusting the outer conductor of the mechanism

14A‧‧‧Outer conductor recess

14B‧‧‧Outer conductor projection

15‧‧‧Injection catheter

16‧‧‧Outer conductor

16A‧‧‧magnetic side outer conductor

16B‧‧‧First transmission outer conductor

16C‧‧‧Second transmission outer conductor

16D‧‧‧Third transmission outer conductor

16E‧‧‧fourth transmission outer conductor

17‧‧‧ Inner conductor

17A‧‧‧First transmission inner conductor

17B‧‧‧Second transfer inner conductor

18‧‧‧Rotating capacitor shaft

19‧‧‧Fixed blades

20‧‧‧Rotating blades

21‧‧‧Rotating capacitor outer peripheral conductor

22‧‧‧charged particle beam

30‧‧‧Acceleration spacing

31‧‧‧ Particle Orbit

32a, 32b‧‧‧ magnetic pole

33‧‧‧Track surface

41‧‧‧ biased electromagnet

42‧‧‧Acceleration chamber

43‧‧‧frequency adjustment mechanism

44‧‧‧Power supply

45‧‧‧ drive

46‧‧‧Rotating rod

47‧‧‧ drive

48‧‧‧Mobile stick

51 to 54‧‧‧ gyro frequency characteristics

55 to 58‧‧‧Resonance frequency characteristics

61a to 61f‧‧‧ dotted line

62a to 62c‧‧‧ dotted line

63a, 63b‧‧‧ dotted line

71‧‧‧Outer conductor projection

a, b‧‧‧ diameter

B‧‧‧ Magnetic field

c‧‧‧Light speed

C ₁ , C ₂ ‧‧‧ capacitor

d‧‧‧Inductance setting distance

Da‧‧‧ movable distance

Db‧‧‧ movable distance

Ε‧‧‧ dielectric constant

F1‧‧‧screw frequency

L‧‧‧Inductance

m‧‧‧Quality

q‧‧‧Charge

R‧‧‧ Radius

γ‧‧‧Lorrentz factor

T1, t2‧‧‧ acceleration time

V‧‧‧speed

WFB1, WFB2‧‧‧ resonance frequency band

WFB3, WFB4‧‧‧ resonance frequency band

Z, Z _L ‧‧‧ synthetic impedance

Z ₀ , Z ₁ , Z ₂ ‧‧‧ Characteristic impedance

Zc, Z _dee ‧‧‧ Characteristic impedance

Zs‧‧‧ impedance

Fig. 1 is a schematic cross-sectional view showing a schematic configuration of a circular accelerator according to a first embodiment of the present invention.

Fig. 2 is a cross-sectional view showing a cross section taken along the line A1-A1 of Fig. 1 showing a schematic configuration diagram of the circular accelerator according to the first embodiment of the present invention.

Fig. 3 is a schematic cross-sectional view showing a schematic configuration diagram of the high-frequency acceleration device of Fig. 2.

Fig. 4 is an enlarged view of the adjustment mechanism of Fig. 3.

Fig. 5 is a cross-sectional view showing the rotary capacitor of the A3-A3 cross section of Fig. 4.

Fig. 6 is a view showing an example of an upper limit value and a lower limit value of a winding frequency in a circular accelerator according to the first embodiment of the present invention.

Fig. 7 is a view showing a modified example of the winding frequency obtained by the frequency adjusting mechanism of Fig. 2.

Fig. 8 is a view showing an example of distribution of characteristic impedance of the high-frequency acceleration device of Fig. 2;

Fig. 9 is a cross-sectional view showing the adjustment mechanism of the A4-A4 cross section of Fig. 4.

Fig. 10 is a view for explaining the necessity of the conductor projections in Fig. 4;

Fig. 11 is a view showing the resonance frequency characteristics of the high-frequency acceleration device according to the first embodiment of the present invention.

Fig. 12 is a view showing the resonance frequency characteristics of the high-frequency acceleration device of the comparative example.

(Embodiment 1)

Fig. 1 is a schematic cross-sectional view showing a schematic configuration of a circular accelerator according to a first embodiment of the present invention. Fig. 2 is a cross-sectional view showing a cross section taken along the line A1-A1 of Fig. 1 showing a schematic configuration diagram of the circular accelerator according to the first embodiment of the present invention. Fig. 3 is a schematic cross-sectional view showing a schematic configuration diagram of the high-frequency acceleration device of Fig. 2. Fig. 4 is an enlarged view of the adjustment mechanism of Fig. 3. Fig. 5 is a cross-sectional view showing the rotary capacitor of the A3-A3 cross section of Fig. 4. Fig. 6 is a view showing an example of an upper limit value and a lower limit value of a winding frequency in a circular accelerator according to the first embodiment of the present invention. Figure 7 A diagram showing a modified example of the winding frequency obtained by the frequency adjustment mechanism of Fig. 2 . Fig. 8 is a view showing an example of distribution of characteristic impedances of the high-frequency acceleration device of Fig. 2; Fig. 9 is a cross-sectional view showing the adjustment mechanism of the A4-A4 cross section of Fig. 4. Fig. 10 is a view for explaining the necessity of the conductor projections in Fig. 4; Fig. 11 is a view showing the resonance frequency characteristics of the high-frequency acceleration device according to the first embodiment of the present invention. Fig. 12 is a view showing the resonance frequency characteristics of the high-frequency acceleration device of the comparative example. The synchrocyclotron 1 belonging to the circular accelerator includes a deflecting electromagnet 41, an ion source 5 disposed at the center of the deflecting electromagnet 41, and a high-frequency acceleration for accelerating the charged particles incident from the ion source 5. Device 2: The accelerated charged particles are taken out to an exit duct 15 outside the accelerator. Further, the charged particles are preferably referred to simply as particles.

The deflecting electromagnet 41 includes two electric coils 3a and 3b disposed with a gap therebetween, and two yokes 4a and 4b opposed to each other, respectively excited by the electric coils 3a and 3b. Magnetic poles 32a, 32b. The high-frequency acceleration device 2 includes a D-type electrode 6, a gap (magnetic pole pitch) disposed between the magnetic pole 32a and the magnetic pole 32b, a dummy D-type electrode 7, and a transmission line 8 for transmitting power to the D-type electrode 6 and dummy D-type electrode 7; acceleration chamber 42 is constituted by transmission line 8, D-type electrode 6 and dummy D-type electrode 7; input port 9 inputs power to acceleration chamber 42; input coupler 10 And a variable capacitive reactance element (rotating capacitor 11) and a frequency adjusting mechanism 43 that change the resonant frequency of the acceleration chamber 42. The variable capacitive reactance element is, for example, a rotary capacitor 11 . The frequency adjustment mechanism 43 includes an adjustment mechanism inner conductor 12 and a movable short circuit plate composed of a conductor. 13 and adjusting the mechanism outer conductor 14 to adjust the variable band of the resonant frequency changed by the variable capacitive reactance element, that is, the resonant frequency band.

The high-frequency acceleration device 2 has a coaxial structure and has an outer conductor 16 and an inner conductor 17. The outer conductor 16 of the high-frequency acceleration device 2 has five regions, and the inner conductor 17 of the high-frequency acceleration device 2 has two regions. The outer conductors 16 in the five regions are a magnetic pole side outer conductor 16A, a first transmitting outer conductor 16B, a second transmitting outer conductor 16C, a third transmitting outer conductor 16D, and a fourth transmitting outer conductor 16E, respectively. The magnetic pole side outer conductor 16A is the outer conductor 16 in the region between the broken line 61a and the broken line 61b, and the first transmission outer conductor 16B is the outer conductor 16 in the region between the broken line 61b and the broken line 61c. The second transfer outer conductor 16C is the outer conductor 16 in the region between the broken line 61c and the broken line 61d, and the third transfer outer conductor 16D is the outer conductor 16 in the region between the broken line 61d and the broken line 61e, the fourth transfer outer The conductor 16E is the outer conductor 16 in the region between the broken line 61e and the broken line 61f. The inner conductor 17 in the two regions is the first transfer inner conductor 17A and the second transfer inner conductor 17B, respectively. The first transfer inner conductor 17A is the inner conductor 17 in the region between the broken line 62a and the broken line 62b, and the second transfer inner conductor 17B is the inner conductor 17 in the region between the broken line 62b and the broken line 62c.

The inner conductor 17 in the transmission line 8 is connected to the D-type electrode 6 at the position of the broken line 62a, and the outer conductor 16 is connected to the dummy D-type electrode 7 at the position of the broken line 61a. The electric power from the power source 44 is input from the input port 9, and is supplied to the high-frequency acceleration device 2 through the input coupler 10 that is capacitively coupled to the transmission line 8. Here, an example in which the input coupler 10 is capacitively coupled to the second transfer inner conductor 17B of the inner conductor 17 is shown. Frequency adjustment The mechanism 43 is disposed on the third transmitting outer conductor 16D of the outer conductor 16 and the second transmitting inner conductor 17B of the inner conductor 17 facing the third transmitting outer conductor 16D. The adjustment mechanism inner conductor 12 is connected to the third transfer outer conductor 16D of the inner conductor 17, and is vertically disposed with respect to the third transfer outer conductor 16D of the inner conductor 17. The movable short-circuiting plate 13 is used to electrically connect the inner conductor 17 and the outer conductor 16 at the position of the inner conductor 12 of the adjustment mechanism, that is, to electrically connect them, and the position of the inner conductor 17 along the adjustment mechanism can be adjusted. As shown in Fig. 3, the moving rod 48 is driven by a driving device 47 such as an air cylinder, and the moving rod 48 is connected to the movable short-circuiting plate 13, whereby the movable short-circuiting plate 13 can be moved to an arbitrary position.

The adjustment mechanism outer conductor 14 of the frequency adjustment mechanism 43 has an outer conductor recess 14A which becomes narrower as the second transfer outer conductor 16C and the fourth transfer outer conductor 16E approach the inner conductor 17; and the outer conductor projection 14B It extends from the bottom (the surface on the inner conductor side) of the outer conductor recess 14A toward the outside. The adjustment mechanism inner conductor 12 and the outer conductor convex portion 14B are coaxially constructed.

As shown in FIGS. 4 and 5, the rotary capacitor 11 includes a rotating capacitor outer peripheral conductor 21, a rotary blade 20, a rotary capacitor shaft 18, and a fixed vane 19. The outer peripheral conductor 21 of the rotary capacitor is rotatably coupled to the outer conductor 16 in the transmission line 8. The rotary vane 20 is connected to the outer peripheral conductor 21 of the rotary capacitor, and the fixed vane 19 is connected to the rotary capacitor shaft 18 connected to the inner conductor 17. The outer circumference conductor 21 of the rotary capacitor is connected to the rotating rod 46 as shown in Fig. 3, and the rotating rod 46 is connected to a driving device 45 such as a motor. Rotating blade 20 series The outer circumference conductor 21 of the rotary capacitor is rotated together with the drive unit 45 around the rotary capacitor shaft 18. The rotary capacitor 11 is increased in electrostatic capacitance by the rotation of the rotary vane 20 as the rotary vane 20 is engaged (overlapped) with the fixed vane 19. On the other hand, the rotary capacitor 11 reduces the electrostatic capacitance as the two blades (the fixed blade 19 and the rotary blade 20) are no longer engaged. The shape of the rotating blade 20 and the stationary blade 19 is mechanically processed to meet the time dependence of the required electrostatic capacitance.

Next, the operation of the synchrocyclotron 1 of the first embodiment will be described. A predetermined deflecting magnetic field is formed in the vertical direction of the paper surface of the first drawing by the deflecting electromagnet 41 shown in Figs. 1 and 2 . By this biasing of the magnetic field, the particles incident from the ion source 5 are orbitally moved like the particle track 31 on the track surface 33 of the gap between the magnetic pole 32a and the magnetic pole 32b, that is, the track surface 33 between the magnetic pole pitches. The particles that perform the winding motion form an acceleration electric field at the acceleration pitch 30 by the timing of reaching the acceleration pitch 30 formed by the gap between the D-type electrode 6 and the dummy D-type electrode 7. The particles are accelerated by the accelerating electric field every time they pass the acceleration interval 30, and the energy is increased. As the energy rises, the orbital trajectory of the particles expands. When the particles reach a predetermined energy, they reach the injection duct 15 and are emitted to the outside of the synchrocyclotron 1. A plurality of particles that have reached the predetermined energy are taken out as the charged particle beam 22. The acceleration pitch 30 is a gap (pitch) between the broken line 63a and the broken line 63b described in Fig. 1 . Further, the position indicated by the broken line 63a in Fig. 1 corresponds to the position indicated by the broken line 61a in Fig. 3 .

As the particles are accelerated at the acceleration spacing 30, the effective mass of the particles increases due to the relativistic effect, while the winding frequency decreases. In order for the particles to continue to accelerate at the acceleration interval 30, it is necessary to form an accelerating electric field that reduces the frequency of the winding. For this reason, the resonance frequency of the high-frequency acceleration device 2 and the frequency of the power supplied from the power source 44 are matched with the winding frequency of the reduced particles, and the transmission from the power source 44 through the transmission line 8 is changed to the acceleration interval. 30 times the frequency of electricity. The resonance frequency is determined by the inductance and electrostatic capacitance of the high-frequency acceleration device 2. Since the time until the particles are incident on the synchrocyclotron 1 until the emission is about ms, the variable capacitance reactance element of the high-frequency acceleration device 2 is adapted to be variable in the rotary capacitor 11 such that the electrostatic capacitance can be changed at a high speed. Capacitive reactance components.

The change in the frequency of the winding of the particles is illustrated. In order to simply estimate the change in the winding frequency of the particles, it is considered that, for example, the intensity of the magnetic field formed by the deflection electromagnet 41 is fixed to 6T with respect to the radial direction (from the center to the outer circumferential direction), in the case of charged particles. Protons were accelerated to 235 MeV. The winding frequency f1 of the particles is determined by the following formula (1) by the magnetic field B of the electromagnet 41, the charge q of the particles, the mass m of the particles, and the Lorentz factor γ of the particles.

F1=qB/(2πγm) ‧ ‧ (1) However, the Lorentz factor γ of the particle is determined by the following formula (2) using the velocity v and the speed of light c of the particle.

The initial winding frequency of the proton is obtained by substituting γ into the γ of the formula (1) to obtain 91.4 MHz. On the other hand, since the Lorentz factor γ of 235 MeV corresponding to protons at the time of emission is 1.25, the proton winding frequency at the time of emission is 73.2 MHz from the equation (1). So, from acceleration From the initial stage to the completion of the acceleration, the winding frequency is reduced by about 20%. In order to obtain a resonance frequency that matches the frequency drop, the electrostatic capacitance of the high-frequency acceleration device 2 is changed at a high speed by the rotary capacitor 11.

Further, the orbital radius r of the particles depending on the Lorentz factor γ of the particles and the magnetic field B is determined by the following formula (3). In addition, the track radius r is suitably referred to simply as the radius r.

r=γmv/qB‧‧‧(3)

At this time, the position at which the proton beam belonging to the charged particle beam 22 is taken out from the synchrocyclotron 1 by the equation (3) is a position at which the radius r around the ion source 5 is 0.29 m. The injection duct 15 shown in Fig. 1 is arranged along a track that can be accelerated to a desired energy and accelerate the passage of completed particles.

Next, in the case where the emission energy has been changed, attention is also paid to the use of the same injection duct 15, and it is considered that the emission energy of the particles is changed by adjusting the intensity of the magnetic field B. Fig. 6 is a view showing the emission energy of the particles with respect to the intensity of the magnetic field B, the upper limit value and the lower limit value of the winding frequency of the particles when the emission position is set to the position of the radius r of 0.29 m. The upper limit and the lower limit of the winding frequency of the particles are the winding frequency at the initial stage of acceleration and the winding frequency at the time of emission.

As can be seen from Fig. 6, in order to change the emission energy from, for example, 235 MeV to 68.5 MeV, it is necessary to change the resonance frequency of the high-frequency acceleration device 2 to a wide band of 42.6 MHz from the maximum value of 91.4 MHz to the minimum value. The range of the resonance frequency at this time is approximately ±40% of the average value (center value) of 67.0 MHz. Therefore, it can be known that it must be made The resonance frequency changes to a wide band and becomes a range of ±40% of the approximate average value (center value).

In the synchrocyclotron 1 of the first embodiment, the inductance L of the high-frequency acceleration device 2 is changed by the frequency adjustment mechanism 43 in accordance with the emission energy of the particles. When the inductance L of the high-frequency acceleration device 2 is changed, the distance d from the movable short-circuiting plate 13 to the outer conductor recess 14A of the adjustment mechanism outer conductor 14 is adjusted (see FIG. 9) to change the resonance frequency and The resonant frequency band adjusted by the variable capacitive reactance (rotating capacitor 11). Since the distance d in FIG. 9 is the distance between the inductance L of the high-frequency acceleration device 2, the distance in the ninth diagram is preferably referred to as the inductance setting distance. The basic concepts of changing the resonant frequency and the resonant frequency band will be described using Figs. 7 and 9. The horizontal axis of Fig. 7 is the acceleration time of the particles, and the vertical axis is the winding frequency of the particles. The acceleration time t1 is the time at which the winding frequency becomes the initial stage of the acceleration of the upper limit value. The acceleration time t2 is the time when the winding frequency is the lower limit value.

In Fig. 7, four winding frequency characteristics, i.e., winding frequency characteristics 51, 52, 53, 54 are shown. The winding frequency characteristic 51 is that the emission energy of the particles is 235 MeV, and the inductance setting distance d is the characteristic at d1 of the ninth graph. The winding frequency characteristic 52 is a characteristic in which the emission energy of the particles is 170 MeV and the inductance setting distance d is d2 in the ninth graph. The winding frequency characteristic 53 is such that the emission energy of the particles is 114 MeV, and the inductance setting distance d is the characteristic at d3 of the ninth graph. The winding frequency characteristic 54 is such that the emission energy of the particles is 68.5 MeV, and the inductance setting distance d is d4 of the ninth graph. The four winding frequency characteristics 51, 52, 53, 54 shown in Fig. 7 are An example of the four emission energies shown in Fig. 6 is shown separately.

When the emission energy of the particles is high, since the upper limit frequency and the lower limit frequency of the resonance frequency band also become higher frequencies, the distance d between the movable short-circuit plate 13 and the outer conductor recess 14A of the adjustment mechanism outer conductor 14 is set. Keep it short and set the inductance to low. On the other hand, when the emission energy of the particles is low, since the upper limit frequency and the lower limit frequency of the resonance frequency band also become lower frequencies, the movable short circuit plate 13 is disposed between the outer conductor recess 14A of the adjustment mechanism outer conductor 14. The distance d is kept longer and the inductance is set higher. The relationship of the distance d in Fig. 7 and Fig. 9 is d1 < d2 < d3 < d4.

Fig. 8 shows an example of the distribution of the characteristic impedance in the high-frequency acceleration device 2. In general, in order to change the resonance frequency of the acceleration chamber 42 to the wide band by the rotation capacitor 11, the characteristic impedance of the high-frequency acceleration device 2 is in the central portion of the high-frequency acceleration device 2 (the first transmission outer conductor 16B) The portion of the first transfer inner conductor 17A is low, and becomes higher as it goes toward both ends (the portion of the magnetic pole side outer conductor 16A and the portion on the side of the rotary capacitor 11). The capacitors C ₁ and C _{2 in} Fig. 8 are the capacitance of the acceleration pitch 30 and the capacitance of the rotating capacitor 11, respectively. The broken lines 61a, 62a, 62b, and 62c shown in Fig. 8 are the same as the broken lines 61a, 62a, 62b, and 62c shown in Fig. 3 . The characteristic impedance Z _{dee of} Fig. 8 is the characteristic impedance of a portion of the magnetic pole side outer conductor 16A. The characteristic impedance Z ₁ is a characteristic impedance of a portion of the first transmission inner conductor 17A, and the characteristic impedance Z ₂ is a characteristic impedance of a portion of the second transmission inner conductor 17B. In Fig. 8, the characteristic impedances Z _dee , Z ₁ , and Z ₂ are shown as 20 Ω, 5 Ω, and 30 Ω, respectively.

In order to greatly change the resonance frequency of the acceleration chamber 42 by the frequency adjustment mechanism 43, that is, the adjustment band of the resonance frequency of the high-frequency acceleration device 2, the D-type electrode side (the side of the D-type electrode 6) is viewed from the frequency adjustment mechanism 43. The frequency adjustment mechanism 43 is disposed at a higher position when the combined impedance Z _L is higher. In this case, when the impedance of the frequency adjustment mechanism 43 is set to Zs, the combined impedance Z including the frequency adjustment mechanism 43 is obtained by the following formula (4). In other words, in order to set the combined impedance Z _L to be high, it is effective to include a region having a high characteristic impedance. Therefore, the frequency adjustment mechanism 43 is preferably a portion of the transmission line 8 disposed closest to the characteristic impedance of the rotary capacitor 11, that is, the portion of the second transmission inner conductor 17B.

Z=ZsZ _L / (Zs + Z _L ) ‧ ‧ (4) However, the impedance Zs of the frequency adjustment mechanism 43 is the characteristic impedance Zc, the distance d from the movable short-circuit plate 13 to the outer conductor concave portion 14A, and the wave number The (transfer constant) β is determined by the following formula (5).

Zs=iZc×tan(βd)‧‧‧(5) where i is an imaginary unit.

In the frequency adjustment mechanism 43, the adjustment mechanism inner conductor 12 directly connected to the inner conductor 17 of the transmission line 8 is used, whereby the manufacturability can be improved, and the intersection of the inner conductor 12 of the adjustment mechanism and the inner conductor 17 of the transmission line 8 can be reduced. Heat loss from the interface. The portion of the transmission line 8 in which the frequency adjustment mechanism 43 is disposed has a higher characteristic impedance, that is, the portion of the second transmission inner conductor 17B, and the diameter of the conductor 16 outside the transmission line 8 is significantly larger than the diameter of the inner conductor 17. This is because, for example, when a cylindrical coaxial tube is taken as an example, the characteristic impedance Z ₀ is determined by the following formula (6) using the diameter a of the outer conductor 16 and the diameter b of the inner conductor 17 and the dielectric constant ε. Therefore. That is, in order to increase the characteristic impedance in the portion of the second transfer inner conductor 17B of the transmission line 8, the diameter a of the outer conductor 16 in the portion of the second transfer inner conductor 17B of the transmission line 8 is relative to the inner conductor. The ratio a/b of the diameter b of 17 is larger than the ratio a/b of the diameter a of the conductor 16 to the diameter b of the inner conductor 17 in the portion of the first transmission inner conductor 17A of the transmission line 8. The outer conductor 16 and the inner conductor 17 are designed. In addition, the diameter a and b used to calculate the ratio a/b may be a diameter or a radius.

For example, in order to achieve a characteristic impedance of 30 Ω in a vacuum of a dielectric constant 1, a/b can be set to 1.18 according to the formula (6). When the diameter of the outer conductor 16 is set to, for example, 400 mm, the diameter of the inner conductor 17 is 339 mm, and the interval between the inner conductor 17 and the outer conductor 16 is 30.5 mm. In the example of Fig. 10, in the portion where the distance between the inner conductor 17 and the outer conductor 16 is 30.5 mm, the inductance is changed by the adjustment mechanism inner conductor 12 and the movable short-circuiting plate 13. Fig. 10 shows a frequency adjustment mechanism of a comparative example in which the lengths of the inner conductors 12 of the adjustment mechanism are the same. The outer conductor convex portion 71 of Fig. 10 is a convex portion extending from the outer conductor 16, and corresponds to the adjustment mechanism outer conductor 14 of the first embodiment. In Fig. 10, the gap is 30.5 mm, that is, on the inner side of the outer conductor convex portion 71, although the adjustment mechanism inner conductor 12 is inserted, it belongs to the end portion from the outer conductor convex portion 71 to the outer conductor 16 The movable distance Db of the distance is a movable distance that can be changed by the inductance, and the inductance cannot be changed even if the movable short-circuiting plate 13 moves further inside from the 30.5 mm gap. In the comparative example of Fig. 10, when the inductance is changed by the adjustment mechanism inner conductor 12 and the movable short-circuiting plate 13, a long extension portion which cannot be adjusted in the inner conductor 12 of the adjustment mechanism is generated, that is, the outer conductor 16 is more The area inside. This extension region significantly limits the resonant frequency band to be changed by the movable shorting plate 13.

Therefore, in the frequency adjustment mechanism 43 of the first embodiment, the outer conductor concave portion 14A of the adjustment mechanism outer conductor 14 is provided around the adjustment mechanism inner conductor 12. The distance D shown in the cross-sectional view of the outer conductor 14 of the adjusting mechanism of Fig. 9 corresponds to the shortest distance of the inner conductor 12 of the adjusting mechanism for moving the movable short-circuiting plate 13. The inductance by adjusting the mechanism inner conductor 12 and the outer conductor convex portion 14B increases as the distance from the inner conductor 17 to the movable short-circuiting plate 13 becomes longer. Therefore, in order to shorten the distance D and reduce the inductance that cannot be adjusted by the movable short-circuiting plate 13, the adjustment mechanism outer conductor 14 is provided in the frequency adjustment mechanism 43 of the first embodiment. In Fig. 10, a portion corresponding to the outer conductor convex portion 14B of the frequency adjusting mechanism 43 of the first embodiment and the outer conductor concave portion 14A from the outer conductor convex portion 14B to the outer conductor 16 is shown by a broken line. In the frequency adjustment mechanism of the comparative example, the distance over which the inductance can be adjusted, that is, the movable distance at which the movable short-circuiting plate 13 can move is Db. On the other hand, in the frequency adjustment mechanism 43 of the first embodiment, the distance at which the inductance can be adjusted is the movable distance Da, and the movable distance Da at which the movable short-circuiting plate 13 can move is compared with the movable distance Db of the comparative example. It is long, so it can expand the range of inductance change.

Further, in Fig. 10, a comparative example of the same length including the frequency adjusting mechanism 43 of the adjusting mechanism outer conductor 14 having the outer conductor recess 14A and the adjusting mechanism inner conductor 12 is compared, even if the outer conductor recess is not included. The frequency adjustment mechanism 43 of the 14A may be applied to the frequency adjustment mechanism 43 in which the length of the inner conductor 12 of the adjustment mechanism is increased. Even if the frequency adjustment mechanism 43 in which the length of the inner conductor 12 of the adjustment mechanism is increased without including the outer conductor recess 14A, the adjustment band of the resonance frequency which changes depending on the capacitance adjustment range can be largely changed without The narrow band is localized. At this time, although the length of the frequency adjustment mechanism 43 is long, the adjustment mechanism outer conductor 14 in the frequency adjustment mechanism 43 is only the outer conductor convex portion 14B, and the structure is simplified. On the other hand, in the frequency adjustment mechanism 43 including the adjustment mechanism outer conductor 14 having the outer conductor recess 14A, there is an advantage that the length of the frequency adjustment mechanism 43 is shortened. The high-frequency acceleration device 2 including the frequency adjustment mechanism 43 including the adjustment mechanism outer conductor 14 having the outer conductor recess 14A is used to shorten the length in the circumferential direction belonging to the direction perpendicular to the extending direction of the D-type electrode 6. The extending direction of the D-type electrode 6 is the horizontal direction of Fig. 3, and the peripheral direction is the longitudinal direction of Fig. 3.

The effects of the high-frequency acceleration device 2 of the first embodiment will be described with reference to Figs. 11 and 12 . Fig. 11 is a view showing the resonance frequency characteristics of the high-frequency acceleration device 2 of the first embodiment. For comparison, FIG. 12 shows the results when the high-frequency adjustment mechanism by the electrode plate shown in the high-frequency acceleration device of Patent Document 1 is applied. In FIGS. 11 and 12, the horizontal axis represents the capacitance of the rotary capacitor, and the vertical axis represents the resonance frequency of the high-frequency acceleration device. Used in the calculation of the characteristics of Figure 11 and Figure 12 The characteristic impedance distribution of the high frequency acceleration device is the same. The resonance frequency characteristics 55 and 56 shown in Fig. 11 are distributions of resonance frequencies when the inductance setting distance d is set to 3 cm and 9 cm, respectively. It can be seen that by increasing the inductance setting distance d from 3 cm to 9 cm, it is possible to maintain the distribution shape while reducing the resonance frequency by about 20 MHz. The resonant frequency bands of the resonant capacitors 55, 56 with respect to the electrostatic capacitance of the rotating capacitor of 100 pF to 300 pF are the resonant frequency bands WFB1, WFB2, respectively. The resonant frequency band WFB1 is 33 MHz, and the resonant frequency band WFB2 is 27 MHz. The resonance frequency band WFB2 is 82% of the resonance frequency band WFB1, and the distribution shape of the resonance frequency characteristic 56 sufficiently maintains the distribution shape of the resonance frequency characteristic 55, and is not narrowed.

The resonance frequency characteristics 57 and 58 shown in Fig. 12 are distributions of resonance frequencies when the capacitance obtained by the electrode plates is 0 pF or 300 pF, respectively. The electrostatic capacitance is set to be from 0pF to 300pF by the plate, and the adjustment band of the resonance frequency is reduced, but the distribution shape is narrower than when the electrostatic capacitance of the plate is 0pF. Specifically, when the electrostatic capacitance ranges from 100 to 300 pF and the electrostatic capacitance of the plate is 0 pF, the resonant frequency band WFB3 is 23 MHz. In contrast, the electrostatic capacitance of the plate is set to 300 pF. The WFB4 system is 3MHz. As described above, the resonance frequency band WFB4 is 13% of the resonance frequency band WFB3, and is narrowed in the resonance frequency band of the high-frequency acceleration device by the adjustment mechanism of the electrode plate. On the other hand, in the frequency adjustment mechanism 43 of the first embodiment, when the resonance frequency band of the high-frequency acceleration device 2 is changed, the resonance frequency band can be sufficiently maintained in the wide band. therefore, When the emission energy of the particles in the synchrocyclotron is to be changed, the frequency adjustment mechanism 43 of the first embodiment is advantageous.

As described above, in the high-frequency acceleration device 2 of the first embodiment, the resonance frequency which changes when the energy of the particles is changed can be changed by the position of the movable short-circuiting plate 13 provided in the frequency adjustment mechanism 43. Bands are not narrowed to the resonant frequency band.

In the high-frequency acceleration device 2 of the first embodiment, the inductance setting distance d of the frequency adjustment mechanism 43 is made shorter when the resonance frequency band is increased, and the inductance setting distance d is set when the resonance frequency band is lowered. Longer. In the high-frequency acceleration device 2 of the first embodiment, the arrangement position of the inner conductor 12 of the adjustment mechanism of the frequency adjustment mechanism 43 is disposed at the center of the higher-frequency acceleration device 2, and is further variable-capacitive reactance element (rotary capacitor 11). side. Therefore, the combined impedance Z including the frequency adjustment mechanism 43 can be increased, and the adjustment band of the resonance frequency of the high-frequency acceleration device 2 can be greatly changed. Further, in the high-frequency acceleration device 2 of the first embodiment, the arrangement position of the inner conductor 12 of the adjustment mechanism of the frequency adjustment mechanism 43 is disposed on the side of the variable capacitive reactance element (the rotary capacitor 11), and thus is different from Patent Document 2 The resonance frequency adjusting mechanism is disposed in the vicinity of the acceleration cavity, and the shape of the magnetic pole and the yoke becomes complicated, and the shape of the magnetic pole and the yoke of the synchrocyclotron 1 is not complicated, and the high frequency acceleration device can be 2 is mounted on the synchrocyclotron 1. In the high-frequency acceleration device 2 of the first embodiment, the position of the inner conductor 12 of the adjustment mechanism of the frequency adjustment mechanism 43 is disposed at a position away from the acceleration chamber 42. Therefore, unlike the resonance frequency adjustment mechanism of Patent Document 2, it is easy to achieve The driving device 47 for moving the movable short-circuiting plate 13 The elasticity of the setting position of the driving device 47 can be improved.

In the high-frequency acceleration device 2 of the first embodiment, the frequency adjustment mechanism 43 changes the resonance frequency band to be adjusted by the variable capacitive reactance (rotational capacitor 11) in the range of ±40% of the center value. The energy of the particles to be accelerated by the synchrocyclotron 1 can be changed to, for example, a wide range from 235 MeV to 68.5 MeV. In the examples shown in Fig. 6 and Fig. 7, an example is shown in which the resonance frequency band is changed from +36% of the center value to -38% of the center value, but if the inductance can be set to the distance d The adjustment inner conductor 12, which is longer than the longest d4, is used in the frequency adjustment mechanism 43, and the resonance frequency band can be changed within a range of ±40% of the center value.

The high-frequency acceleration device 2 according to the first embodiment includes the adjustment mechanism inner conductor 12, the movable short-circuiting plate 13, and the adjustment mechanism outer conductor 14 that are directly connected to the inner conductor 17 by the frequency adjustment mechanism 43, so that the manufacturing mechanism of the inner conductor 12 of the adjustment mechanism can be made. The lifting and the heat loss at the interface between the inner conductor 12 of the adjusting mechanism and the inner conductor of the transmission line 8 can be reduced.

Next, a case where the high-frequency acceleration device 2 of the first embodiment is applied to a particle beam therapy device, that is, a case where it is applied to a circular accelerator for particle beam therapy. When the high-frequency acceleration device 2 of the first embodiment is applied to a particle beam therapy device, the energy of a plurality of particles to be taken out from the synchrocyclotron 1 is determined in advance. The distance d corresponding to the inductance of the equal energy should also be determined in advance. When performing treatment, the energy of the best for each affected part is selected from a predetermined energy group (a plurality of energies). In order to set the distance d corresponding to the inductance of the selected energy, the frequency adjustment mechanism 43 can be externally driven by a driving device 47 such as a cylinder before the start of treatment. The short circuit plate 13 is set at an appropriate position.

As described above, the high-frequency acceleration device 2 of the first embodiment is configured to apply a high-frequency electric field to a spiral orbital due to a bias magnetic field formed by the deflection of the electromagnet 41 by the circular accelerator (synchronous cyclotron 1). The charged particles, and the high-frequency acceleration device of the circular accelerator that accelerates the charged particles. The high-frequency acceleration device 2 according to the first embodiment includes an electrode (D-type electrode 6, dummy D-type electrode 7) for applying a high-frequency electric field to the charged particles, and a transmission line 8 having an inner conductor 17 and an inner conductor. The outer conductor 16 of the 17 and transmits high frequency power to the electrodes (D-type electrode 6, dummy D-type electrode 7); the acceleration chamber 42 is connected to the electrode by the transmission line 8 (D-type electrode 6, dummy D-type electrode 7) And the variable capacitance capacitive element (rotating capacitor 11) and the frequency adjusting mechanism 43 change the resonance frequency of the acceleration chamber 42. The frequency adjustment mechanism 43 of the high-frequency acceleration device 2 of the first embodiment is characterized in that the adjustment mechanism inner conductor 12 is connected to the inner conductor 17 of the transmission line 8 and extends in a direction away from the inner conductor 17; The conductor 14 is connected to the outer conductor 16 of the transmission line 8 and encloses the adjustment mechanism inner conductor 12; and the movable short-circuiting plate 13 is composed of a conductor, and electrically connects the adjustment mechanism inner conductor 12 and the adjustment mechanism outer conductor 14, Further, it is arranged to change the connection position with the adjustment mechanism inner conductor 12 and the adjustment mechanism outer conductor 14. According to the high-frequency acceleration device 2 of the first embodiment, the adjustment band of the resonance frequency that changes in accordance with the capacitance adjustment range can be greatly changed without narrowing the band.

The circular accelerator (synchronous cyclotron 1) of the first embodiment is a charged particle that is incident from the ion source 5 to the center by a biasing magnetic field. A circular accelerator that is wound along a spiral orbit and accelerated by a high-frequency electric field. The circular accelerator (synchronous cyclotron 1) according to the first embodiment includes a deflecting electromagnet 41 that forms a biasing magnetic field, a high-frequency acceleration device 2 that accelerates the charged particles, and an accelerated charged particle to the circular shape. The injection duct 15 outside the accelerator, and the high-frequency acceleration device 2 is characterized by comprising: an electrode (D-type electrode 6, a dummy D-type electrode 7) applying a high-frequency electric field to the charged particles; and a transmission line 8 having an inner conductor 17 And surrounding the outer conductor 16 of the inner conductor 17, and transmitting high frequency power to the electrodes (D-type electrode 6, dummy D-type electrode 7); the acceleration chamber 42 is connected by the transmission line 8 and the electrode (D-type electrode 6, dummy The D-type electrode 7) is configured, and the variable capacitance reactance element (the rotating capacitor 11) and the frequency adjustment mechanism 43 change the resonance frequency of the acceleration chamber 42. The frequency adjustment mechanism 43 of the high-frequency acceleration device 2 of the first embodiment is characterized in that the adjustment mechanism inner conductor 12 is connected to the inner conductor 17 of the transmission line 8 and extends in a direction away from the inner conductor 17; The conductor 14 is connected to the outer conductor 16 of the transmission line 8 and encloses the adjustment mechanism inner conductor 12; and the movable short-circuiting plate 13 is composed of a conductor, and electrically connects the adjustment mechanism inner conductor 12 and the adjustment mechanism outer conductor 14, Further, it is arranged to change the connection position with the adjustment mechanism inner conductor 12 and the adjustment mechanism outer conductor 14. According to the above-described feature, the circular accelerator (synchronous cyclotron 1) of the first embodiment can greatly change the adjustment band of the resonance frequency which changes depending on the capacitance adjustment range by the high-frequency acceleration device 2, without being narrow. The banding is performed to emit a charged particle beam 22 suitable for the energy of the affected part belonging to the particle beam treatment subject.

The high frequency of Embodiment 1 has been described so far. The acceleration device 2 is applied to an example of a synchrocyclotron, but the high-frequency acceleration device 2 of the first embodiment can also be applied to a cyclotron. In the cyclotron, the resonance frequency of the high-frequency acceleration device 2 is fixed. However, in the cyclotron, fine adjustment is performed when a fixed value of the resonance frequency deviates for some reason. In the cyclotron, in the fine adjustment of the resonance frequency, the entire length of the high-frequency acceleration device is generally adjusted, so that a large adjustment mechanism is necessary. However, in the high-frequency acceleration device 2 according to the first embodiment of the present invention, as described above, the small-sized frequency adjustment mechanism 43 can change the resonance frequency only by adjusting the position of the movable short-circuiting plate 13. For example, it can be seen from the characteristics 51, 52, 53, 54 in the acceleration time t1 of FIG. 7 that even if the electrostatic capacitance of the rotary capacitor 11 is the same in the characteristics 51, 52, 53, 54, only the frequency adjustment mechanism 43 is changed. The distance d changes the winding frequency to be determined by the resonance frequency. Therefore, the high-frequency acceleration device 2 according to the first embodiment of the present invention is applied to the cyclotron. The high-frequency acceleration device 2 according to the first embodiment of the present invention can also change the resonance frequency by adjusting the position of the movable short-circuiting plate 13.

Further, in the present invention, the respective embodiments can be freely combined within a compatible range, and the respective embodiments can be appropriately changed or omitted.

Claims (13)

A high-frequency acceleration device for a circular accelerator, which applies a high-frequency electric field to charged particles that are wound along a spiral orbit due to a biasing magnetic field formed by a biasing electromagnet of a circular accelerator, and accelerates the charged particles; The high-frequency acceleration device of the shape accelerator includes: an electrode that applies a high-frequency electric field to the charged particles; and a transmission line that has an inner conductor and an outer conductor surrounding the inner conductor, and transmits high-frequency power to the electrode; The transmission line and the electrode are configured by the transmission line; and the variable capacitance reactance element and the frequency adjustment mechanism change the resonance frequency of the acceleration cavity; and the frequency adjustment mechanism includes: an adjustment mechanism inner conductor connected to the The inner conductor of the transmission line extends in a direction away from the inner conductor; the outer conductor of the adjustment mechanism is connected to the outer conductor of the transmission line, and surrounds the inner conductor of the adjustment mechanism; the movable short-circuiting plate is a conductor And electrically connected to the inner conductor of the adjusting mechanism and the outer conductor of the adjusting mechanism, and It is set to be changed within a connection position with the outer conductor and the adjusting means of the adjusting mechanism conductors. The high-frequency acceleration device for a circular accelerator according to claim 1, wherein the adjustment mechanism outer guide system comprises: an outer conductor recess, the bottom portion of which is disposed closer to the inner conductor than the outer conductor; and The outer conductor convex portion extends from the aforementioned bottom portion of the outer conductor concave portion toward the outer peripheral direction. The high-frequency acceleration device for a circular accelerator according to claim 1, further comprising: a driving device for moving the position of the movable short-circuiting plate; and the acceleration cavity that can be changed by the variable capacitive reactance element When the band of the resonance frequency, that is, the resonance frequency band, rises in a direction in which the resonance frequency is high, the driving device moves the movable short-circuiting plate to the end of the inner conductor side of the outer conductor of the adjustment mechanism. The distance between the portions is shortened; when the resonance frequency band is lowered in a direction lower than the resonance frequency, the driving device moves the movable short-circuiting plate to the end of the inner conductor side of the outer conductor of the adjustment mechanism The distance between the parts becomes longer. The high-frequency acceleration device for a circular accelerator according to claim 2, further comprising: a driving device for moving the position of the movable short-circuiting plate; and the acceleration cavity that can be changed by the variable capacitive reactance element When the region of the resonant frequency, that is, the resonant frequency band, rises in a direction in which the resonant frequency is high, the driving device moves the movable short-circuiting plate to be in front of the outer conductive concave portion of the outer conductor of the adjusting mechanism. The distance of the bottom portion is shortened; when the resonance frequency band is lowered in a direction lower than the resonance frequency, the driving device moves the movable short-circuiting plate to The distance from the aforementioned bottom portion of the outer conductor recess in the outer conductor of the adjustment mechanism becomes long. The high-frequency acceleration device for a circular accelerator according to the third or fourth aspect of the invention, wherein the frequency adjustment mechanism is configured to set a maximum value and a minimum value among the aforementioned resonance frequencies of the acceleration cavity. The center frequency value includes at least a range of -40% to +40%, and the resonance frequency band to be changed by the variable capacitance reactance element is changed. The high-frequency acceleration device for a circular accelerator according to any one of claims 1 to 4, wherein the frequency adjustment mechanism is disposed at a position away from the electrode side, and is disposed in the variable capacitor Side of the reactive component. The high-frequency acceleration device for a circular accelerator according to claim 6, wherein the frequency adjustment mechanism is disposed farther from the electrode than a center position of the extending direction of the structure of the electrode and the transmission line. At the office. The high-frequency acceleration device for a circular accelerator according to any one of claims 1 to 4, wherein the frequency adjustment mechanism is to change a high-frequency acceleration device from which the circular accelerator is mounted. When the circular accelerator emits the energy of the charged particles, the arrangement position of the movable short-circuiting plate is changed. A circular accelerator is characterized in that a charged magnetic particle that is incident from a source to a center is accelerated by a high-frequency electric field while being rotated along a spiral orbit by a biasing magnetic field; the circular accelerator includes: And a high-frequency acceleration device for a circular accelerator according to any one of the first to eighth aspects of the present invention, wherein the charged particles are accelerated; and the injection conduit is The accelerated charged particles are emitted outside the circular accelerator. The high-frequency acceleration device for a circular accelerator according to claim 5, wherein the frequency adjustment mechanism is disposed at a position away from the electrode side and disposed on the variable capacitive reactance element side. The high-frequency acceleration device for a circular accelerator according to claim 5, wherein the frequency adjustment mechanism is configured to change the charge from the circular accelerator that is mounted on the high-frequency acceleration device in which the circular accelerator is mounted. When the energy of the particles is changed, the arrangement position of the movable short-circuiting plate is changed. The high-frequency acceleration device for a circular accelerator according to the sixth aspect of the invention, wherein the frequency adjustment mechanism is configured to change the charge from the circular accelerator that is mounted on the high-frequency acceleration device on which the circular accelerator is mounted. When the energy of the particles is changed, the arrangement position of the movable short-circuiting plate is changed. The high-frequency acceleration device for a circular accelerator according to claim 7, wherein the frequency adjustment mechanism is configured to change the charge from the circular accelerator that is mounted on the high-frequency acceleration device in which the circular accelerator is mounted. When the energy of the particles is changed, the arrangement position of the movable short-circuiting plate is changed.