JP2000156299A - High-frequency acceleration cavity, synchrotron, corpuscular beam curing device and radiant-ray generation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the possibility of discharge between an accelerating tube and a bias winding with a simple structure without degrading accelerating performance by providing an electromagnet that is installed outside a ring-like ferromagnetic and generates magnetic flux and by setting the direction of the magnetic flux passing through the electromagnet in parallel with the circumference direction of the ring-like ferromagnetic. SOLUTION: An electromagnet 7 generating magnetic flux is installed outside a ring-like ferromagnetic 3. A structure wherein the electromagnet 7 does not spatially interfere with the transporting system of a charged corpuscular beam can be composed by setting the direction of the magnetic flux passing through an iron core 8 constituting the electromagnet 7 in parallel with the circumference direction of the ring-like ferromagnetic 3. Because an accelerating tube 1 penetrates the central part of the ring-like ferromagnetic 3, a space between the accelerating tube 1 and the ring-like ferromagnetic 3 can effectively be used, and the device can be miniaturized by integrating the accelerating tube 1 with the ring-like ferromagnetic 3. Additionally, heating loss caused by high-frequency waves can be reduced by using a ferrite for the ring-like ferromagnetic 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency accelerating cavity for accelerating charged particles such as ions and electrons, a synchrotron using the high-frequency accelerating cavity, a particle beam therapy system using the synchrotron, and synchrotron radiation. It relates to a generator.

[0002]

2. Description of the Related Art In a synchrotron, which is an accelerator for charged particles such as ions and electrons, the speed of the particles increases with acceleration, and the time required for one round of the synchrotron decreases. Assuming that the velocity of the charged particles is v and the frequency of the high-frequency acceleration voltage is f, the distance that the charged particles travel during one cycle of this frequency is
v / f. Note that the time for the charged particles to make one round of the synchrotron needs to be an integral multiple of the period of the high-frequency acceleration voltage. That is, assuming that the length of one circumference of the synchrotron is L, the following equation (1) holds.

L = hv / f (1) Here, h is an integer and is called a harmonic number. From equation (1), v and f are in a proportional relationship, and it is necessary to increase the frequency f as the charged particles accelerate.

In a synchrotron, a high accelerating voltage of usually several kV to several tens kV is required. Therefore, a cavity resonator is used to generate this accelerating voltage. A cavity usually has a unique resonance frequency, and does not generate an accelerating voltage at other frequencies. For this reason, in a synchrotron, a ferrite, which is usually a ferromagnetic substance, is inserted into a cavity resonator, a magnetic flux flows through the ferrite, and the inductance is changed by changing the magnetic permeability of the ferrite, thereby changing the resonance frequency f, and v and v Is in tune.

[0005] The ferrite usually has a ring shape, and an accelerating tube penetrates the center of the ring. As a method of flowing a magnetic flux through the ferrite, there are a method of flowing the magnetic flux in the axial direction of the ferrite and a method of flowing the magnetic flux in the circumferential direction. In a high-frequency accelerating cavity that requires a wide range in which the resonance frequency changes, it is necessary to flow magnetic flux in the circumferential direction.

As a method of flowing a magnetic flux in the circumferential direction of the ferrite, conventionally, a method of winding a coil called a bias winding around the ferrite and flowing a current to the coil has been adopted. Bias winding is a simple one-way winding,
A high frequency is applied to the bias winding, which adversely affects the current source of the bias winding. Therefore, for example, a method has been adopted in which the ferrite is divided into two parts, and each bias winding is wound in an eight-shape so that the winding of the bias winding around each ferrite is opposite to each other. The configuration of such a high-frequency accelerating cavity will be described below.

FIG. 4 is a cross-sectional view parallel to the beam axis of charged particles showing the configuration of a conventional high-frequency accelerating cavity. Accelerator tube 1
Is a container that is kept in a vacuum so that charged particles travel as a beam inside the container. The acceleration gap 2 is made of an insulator, generates a high-frequency electric field in which charged particles are accelerated, and is directly connected to the acceleration tube 1. The ferrite 3 has a ring shape, and a plurality of ferrites 3 are stacked one on another. The bias winding 4 is a coil for flowing a magnetic flux in the circumferential direction of the ferrite 3, and a current flows.

[0008] The outer container 5 covers the accelerating tube 1, the accelerating gap 2, and the ferrite 3, and prevents the high frequency from leaking to the outside. The RF power amplifier 6 supplies high-frequency power, applies a high-frequency voltage to the acceleration tube 1, and generates a high-frequency electric field inside the acceleration gap 2. In order to generate a high-frequency electric field required for accelerating charged particles inside the acceleration gap 2, a specified amount of high-frequency power must be supplied. The magnetic flux flowing through the ferrite 3 is proportional to the product of the number n of turns of the bias winding 4 and the current value I flowing through the bias winding 4, and the current value I is changed to change the resonance frequency f. In order to flow a specified amount of magnetic flux through the ferrite 3, the number of turns n
And the maximum current value Imax must be constant.

[0009]

In the above-described high-frequency accelerating cavity, the distance between the bias winding 4 and the accelerating tube 1 is short. Discharge may occur between the line 4 and the accelerator tube 1. When the discharge occurs, the bias winding 4 and the accelerating tube 1 may be damaged, so that a specified amount of high-frequency power cannot be supplied. Further, if the inner diameter of the ferrite 3 is increased to prevent discharge and the distance between the bias winding 4 and the accelerator tube 1 is increased, the outer diameter of the ferrite 3 increases, and the manufacturing cost of the ferrite 3 increases.

Further, in the high-frequency accelerating cavity described above, the product of the number n of turns of the bias winding 4 for flowing a specified amount of magnetic flux through the ferrite 3 and the maximum current value Imax flowing through the bias winding 4 is determined. Therefore, the configuration of the device becomes complicated for the following reasons.

That is, when the maximum current value Imax is increased in order to reduce the number of turns n, the cross-sectional area of the conductor of the bias winding 4 is increased or the bias winding is increased in order to suppress a temperature rise due to Joule heat of the bias winding 4. The wire 4 needs to be cooled with water or the like. If the cross-sectional area of the conductor is increased, it becomes difficult to bend the bias winding 4 into a coil shape, and if a plurality of straight portions are connected to form a coil shape without bending, the connecting portion becomes complicated. Also, when the bias winding 4 is cooled with water or the like, the structure of the bias winding 4 is complicated.

On the other hand, increasing the number n of turns to reduce the maximum current value Imax makes the complicated bias winding 4 more complicated. Further, in the high-frequency accelerating cavity described above, since the bias winding 4 exists between the ferrite 3 and the accelerating tube 1, an unnecessary space is required as a resonator.

An object of the present invention is to provide a high-frequency accelerating cavity which has a simple structure and eliminates the possibility of electric discharge between an accelerating tube and a bias winding without impairing the accelerating performance, a synchrotron, a particle beam therapy system and radiation. An object of the present invention is to provide a light generating device.

[0014]

In order to solve the above-mentioned problems and to achieve the object, a high-frequency accelerating cavity, a synchrotron, a particle beam therapy system and a synchrotron radiation generator of the present invention are configured as follows.

(1) The high-frequency accelerating cavity of the present invention is a high-frequency accelerating cavity in which charged particles are accelerated at a central portion of the ring-shaped ferromagnetic material by flowing a magnetic flux in a circumferential direction of the ring-shaped ferromagnetic material. An electromagnet is provided outside the ring-shaped ferromagnetic material and generates the magnetic flux.

(2) The high-frequency accelerating cavity of the present invention is the high-frequency accelerating cavity described in the above (1), and the direction of the magnetic flux flowing through the electromagnet is parallel to the circumferential direction of the ring-shaped ferromagnetic material. .

(3) The high-frequency accelerating cavity of the present invention is the high-frequency accelerating cavity according to the above (1) or (2), and an accelerating tube penetrates the center of the ring-shaped ferromagnetic material. The charged particles are accelerated in the accelerating tube.

(4) The high-frequency accelerating cavity of the present invention is the high-frequency accelerating cavity according to the above (1) or (2), and is made of a metal having a center portion of the ring-shaped ferromagnetic material branched from an accelerating tube. A tube penetrates and accelerates charged particles within the metal tube.

(5) The high-frequency accelerating cavity of the present invention is the high-frequency accelerating cavity according to any one of the above (1) to (4), and ferrite is used as the ring-shaped ferromagnetic material.

(6) The synchrotron of the present invention uses the high-frequency accelerating cavity described in the above (1).

(7) The particle beam therapy system of the present invention uses the synchrotron described in (6) above as a charged particle accelerator.

(8) In the synchrotron radiation generator of the present invention, the synchrotron described in (6) above is used as an electron accelerator.

As a result of taking the above-described measures, the following effects are obtained.

(1) According to the high frequency accelerating cavity of the present invention,
Since a magnetic flux flowing in the circumferential direction of the ring-shaped ferromagnetic material used as a tuner is generated by an electromagnet provided outside the ring-shaped ferromagnetic material, a bias winding around the ring-shaped ferromagnetic material can be removed. . That is, a bias winding around the ring-shaped ferromagnetic material is not required, and a discharge between the bias winding and the accelerating tube can be eliminated, thereby simplifying the structure.

(2) According to the high frequency accelerating cavity of the present invention,
Since the direction of the magnetic flux flowing through the iron core forming the electromagnet is parallel to the circumferential direction of the ring-shaped ferromagnetic material, the electromagnet can be configured not to spatially interfere with the transport system of the charged particle beam.

(3) According to the high frequency accelerating cavity of the present invention,
Since the accelerating tube penetrates the center of the ring-shaped ferromagnetic material, the space between the accelerating tube and the ring-shaped ferromagnetic material can be effectively used, and the accelerating tube and the ring-shaped ferromagnetic material can be effectively used. Are integrated, and the device becomes compact.

(4) According to the high frequency accelerating cavity of the present invention,
The accelerator tube does not penetrate the center of the ring-shaped ferromagnetic material,
Since the metal tube branched from the accelerating tube penetrates the center of the ring-shaped ferromagnetic material, by using a pair of the metal tube and the ring-shaped ferromagnetic material, the variable region of the resonance frequency can be reduced. Can be wider.

(5) According to the high frequency accelerating cavity of the present invention,
Since ferrite is used as the ring-shaped ferromagnetic material, the heat loss of the ring-shaped ferromagnetic material due to high frequency can be reduced, and the resonance frequency variable region of the high-frequency accelerating cavity can be widened, and the repetition period is fast. It can be applied to synchrotrons.

(6) According to the synchrotron of the present invention,
The use of the high-frequency accelerating cavity of the above (1) eliminates the possibility of discharge between the bias winding and the accelerating tube, which has been a problem in the past, and enables stable operation. In addition, since the cause of discharge is reduced by one and the acceleration voltage of the high frequency acceleration cavity can be kept high,
Acceleration performance is improved.

(7) According to the particle beam therapy system of the present invention,
Since the synchrotron of the above (6) is used as a charged particle accelerator, stable operation can be performed and patient treatment can be appropriately performed in a stable state.

(8) According to the synchrotron radiation generator of the present invention,
Since the synchrotron of the above (6) is used as the electron accelerator, stable operation can be performed, and the efficiency of research using the synchrotron radiation generator and the productivity of products are improved.

[0032]

FIG. 1 is a cross-sectional view of a high-frequency accelerating cavity according to an embodiment of the present invention, which is parallel to the beam axis of charged particles. In FIG. 1, the inside of an acceleration tube 1 is maintained in a vacuum, and charged particles travel inside the inside as a beam. The acceleration gap 2 is made of an insulator, generates a high-frequency electric field in which charged particles are accelerated, and is directly connected to the acceleration tube 1. Ferrite 3 has a ring shape,
A plurality of the tubes are overlapped, and the accelerating tube 1 penetrates the central portion thereof.

The external vessel 5 covers the acceleration tube 1, the acceleration gap 2, and the ferrite 3, and prevents high frequency from leaking to the outside. The RF power amplifier 6 supplies high-frequency power, applies a high-frequency voltage to the acceleration tube 1, and generates a high-frequency electric field inside the acceleration gap 2. The electromagnet 7 includes an iron core 8 and a coil 9.

FIG. 2 is a sectional view perpendicular to the beam axis of the charged particles showing the structure of the high-frequency accelerating cavity. 2, the same parts as those in FIG. 1 are denoted by the same reference numerals. As shown in FIG. 2, the iron core 8 has a C-shape so as to sandwich the outer container 5 and the ferrite 3 therein. The coil 9 is wound around the iron core 8. When a current flows through the coil 9, a magnetic flux flows through the iron core 8, and further, a magnetic flux flows through the ferrite 3 sandwiched between the iron cores 8.

FIG. 3 is a diagram showing the magnetic flux flowing through the ferrite 3. As shown in FIG.
Along the circumferential direction, so as to be parallel to the circumferential direction. The resonance frequency of the high-frequency accelerating cavity is changed by the following principle. That is, by changing the current flowing through the coil 9, the magnetic flux flowing through the iron core 8 and the ferrite 3 is changed, and by changing the magnetic permeability of the ferrite 3, the ferrite 3 is changed.
And the resonance frequency of the high-frequency accelerating cavity.

The present invention is not limited to the above-described embodiment, but can be implemented with appropriate modifications without departing from the scope of the invention.
For example, the acceleration tube 1 does not penetrate the center of the ferrite 3 but a metal tube (not shown) branched from the acceleration tube penetrates the center of the ferrite 3 to accelerate charged particles in the metal tube. May be.

A synchrotron can be formed by using the high-frequency accelerating cavity described in the above embodiment.
Further, a particle beam therapy system can be configured using the synchrotron as a charged particle accelerator, and a synchrotron radiation generator can be configured using the synchrotron as an electron accelerator.

(Summary of Embodiment) The configuration, operation and effect shown in the embodiment are summarized as follows.

[1] In the high-frequency accelerating cavity described in the embodiment, the magnetic flux flows in the circumferential direction of the ring-shaped ferromagnetic material (3) to charge the center of the ring-shaped ferromagnetic material (3). The high-frequency accelerating cavity for accelerating particles includes an electromagnet 7 installed outside the ring-shaped ferromagnetic body (3) to generate the magnetic flux.

As described above, in the high-frequency accelerating cavity, the magnetic flux flowing in the circumferential direction of the ring-shaped ferromagnetic material (3) used as a tuner is controlled by the electromagnet 7 provided outside the ring-shaped ferromagnetic material (3). To do so, the bias winding 4 around the ring-shaped ferromagnetic material (3) can be removed. That is, the bias winding 4 around the ring-shaped ferromagnetic body (3) becomes unnecessary, and the discharge between the bias winding 4 and the accelerating tube 1 can be eliminated, thereby simplifying the structure.

[2] The high-frequency accelerating cavity described in the embodiment is the high-frequency accelerating cavity described in the above [1], and the direction of the magnetic flux flowing through the electromagnet 7 is the same as that of the ring-shaped ferromagnetic material (3). ) Is parallel to the circumferential direction.

As described above, in the high-frequency accelerating cavity, since the direction of the magnetic flux flowing through the iron core 8 forming the electromagnet 7 is parallel to the circumferential direction of the ring-shaped ferromagnetic material (3), the charged particle beam is transported. The electromagnet 7 can be configured not to spatially interfere with the system.

[3] The high-frequency accelerating cavity described in the embodiment is the high-frequency accelerating cavity described in the above [1] or [2], and the center of the ring-shaped ferromagnetic material (3) is located at the center. The acceleration tube 1 penetrates and accelerates charged particles in the acceleration tube 1.

As described above, in the high-frequency accelerating cavity, since the accelerating tube 1 penetrates the center of the ring-shaped ferromagnetic material (3), the accelerating tube 1 and the ring-shaped ferromagnetic material (3) are used. While effectively utilizing the space between
The accelerating tube 1 and the ring-shaped ferromagnetic material (3) are integrated, and the device becomes compact.

[4] The high-frequency accelerating cavity described in the embodiment is the high-frequency accelerating cavity described in the above [1] or [2], and the center of the ring-shaped ferromagnetic material (3) is formed. A metal pipe branched from the acceleration pipe 1 penetrates and accelerates the charged particles in the metal pipe.

As described above, in the high-frequency accelerating cavity described above, the accelerating tube 1 does not penetrate the center of the ring-shaped ferromagnetic body (3), and the metallic tube branched from the accelerating tube 1 has the ring-shaped ferromagnetic material. Since it penetrates through the center of the body (3), the use of one set of the metal tube and the ring-shaped ferromagnetic body (3) makes it possible to widen the variable region of the resonance frequency.

[5] The high-frequency accelerating cavity described in the embodiment is the high-frequency accelerating cavity according to any one of the above [1] to [4], and is used as the ring-shaped ferromagnetic material (3). Ferrite 3 was used.

As described above, in the high-frequency accelerating cavity, since the ferrite 3 is used as the ring-shaped ferromagnetic material (3), heat loss of the ring-shaped ferromagnetic material (3) due to high frequency can be reduced. In addition, the variable region of the resonance frequency of the high-frequency accelerating cavity can be widened, and it can be applied to a synchrotron with a fast repetition period.

[6] The synchrotron described in the embodiment uses the high-frequency accelerating cavity described in the above [1].

As described above, since the synchrotron uses the high-frequency accelerating cavity of the above [1], the possibility of discharge between the bias winding 4 and the accelerating tube 1 which has been a problem in the related art is eliminated, and the synchrotron is stabilized. Operation is possible. Further, since the factor of the discharge is reduced by one and the acceleration voltage of the high frequency acceleration cavity can be kept high, the acceleration performance is improved.

[7] The particle beam therapy system described in the embodiment uses the synchrotron described in the above [6] as a charged particle accelerator.

As described above, in the above-mentioned particle beam therapy system, since the synchrotron of the above [6] is used as an accelerator for charged particles, stable operation can be performed, and treatment of a patient can be appropriately performed in a stable state. .

[8] In the synchrotron radiation generator described in the embodiment, the synchrotron described in the above [6] is used as an electron accelerator.

As described above, in the above-mentioned synchrotron radiation generator, since the synchrotron of the above [6] is used as the electron accelerator, stable operation can be performed, and the efficiency of research using the synchrotron radiation generator and the efficiency of products can be improved. Productivity is improved.

[0055]

According to the present invention, it is possible to eliminate the possibility of discharge between the accelerating tube and the bias winding without deteriorating the acceleration performance, to simplify the structure of the device, and to facilitate the production.
A high-frequency accelerating cavity of a variable resonance frequency that does not waste the space between the ferromagnetic material and the accelerating tube, a synchrotron using the high-frequency accelerating cavity, a particle beam therapy device using the synchrotron, and radiation light A generator can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view parallel to a beam axis of a charged particle, showing a structure of a high-frequency acceleration cavity according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view perpendicular to the beam axis of the charged particles, showing the structure of the high-frequency acceleration cavity according to the embodiment of the present invention.

FIG. 3 is a diagram showing a magnetic flux flowing through the ferrite according to the embodiment of the present invention.

FIG. 4 is a cross-sectional view of a high-frequency accelerating cavity according to a conventional example, which is parallel to a beam axis of charged particles.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Accelerator tube 2 ... Acceleration gap 3 ... Ferrite 4 ... Bias winding 5 ... External container 6 ... RF power amplifier 7 ... Electromagnet 8 ... Iron core 9 ... Coil 10 ... Magnetic flux

Claims (8)

[Claims] 1. A high-frequency accelerating cavity in which a charged particle is accelerated at a central portion of the ring-shaped ferromagnetic material by flowing a magnetic flux in a circumferential direction of the ring-shaped ferromagnetic material. And a high-frequency accelerating cavity comprising an electromagnet for generating the magnetic flux. 2. The high-frequency accelerating cavity according to claim 1, wherein a direction of a magnetic flux flowing through the electromagnet is parallel to a circumferential direction of the ring-shaped ferromagnetic material. 3. The high-frequency accelerating cavity according to claim 1, wherein an accelerating tube penetrates a center portion of the ring-shaped ferromagnetic material, and accelerates charged particles in the accelerating tube. 4. The metal ferromagnetic material according to claim 1, wherein a metal tube branched from an accelerating tube penetrates a center portion of the ring-shaped ferromagnetic material, and accelerates charged particles in the metal tube. The high frequency accelerating cavity described. 5. The high frequency acceleration cavity according to claim 1, wherein ferrite is used as said ring-shaped ferromagnetic material. 6. A synchrotron using the high-frequency accelerating cavity according to claim 1. 7. A particle beam therapy system using the synchrotron according to claim 6 as a charged particle accelerator. 8. A synchrotron according to claim 6, wherein the synchrotron is used as an electron accelerator.