WO2018096648A1

WO2018096648A1 - Accelerator and particle beam irradiation device

Info

Publication number: WO2018096648A1
Application number: PCT/JP2016/084969
Authority: WO
Inventors: 孝義関
Original assignee: 株式会社日立製作所
Priority date: 2016-11-25
Filing date: 2016-11-25
Publication date: 2018-05-31

Abstract

In this accelerator 50, a main magnetic pole 1 has a recess 1B in the surface that is on the side of an outer peripheral surface 1A which faces away from the surface opposing another main magnetic pole 1. In an ion source 3, a discharge chamber 105 and a magnetic path 103 are disposed more inward than the outer peripheral surface 1A of the main magnetic pole 1 when the main magnetic pole 1 is viewed from a vertical direction cross section. In other words, the discharge chamber and the magnetic path are disposed in the recess 1B of the main magnetic pole 1. In this manner, a beam line can be shortened, providing an external ion source type accelerator that does not use a large-scale device, and a particle beam irradiation device equipped therewith.

Description

Accelerator and particle beam irradiation device

The present invention relates to an accelerator for accelerating ions such as protons and carbon and a particle beam irradiation apparatus including the accelerator.

Patent Document 1 describes the use of an ion source installed outside in a cyclotron accelerator. This Patent Document 1 describes a device configuration from when an ion beam is incident on a cyclotron from an external ion source.

US Pat. No. 3,794,927

Patent Document 1 described above describes a cyclotron accelerator having an external ion source type incident system for injecting an ion beam from the outside. However, the arrangement of the ion source described in Patent Document 1 requires many lens mechanisms on the beam line. For this reason, there has been a problem that the apparatus becomes complicated and large.

An object of the present invention is to provide an external ion source type accelerator that can shorten a beam line and does not use a large-scale apparatus, and a particle beam irradiation apparatus including the accelerator.

In order to solve the above problems, for example, the configuration described in the claims is adopted.

The present invention includes a plurality of means for solving the above-described problems. For example, an ion source having at least a discharge chamber, a coil, and a magnetic path, and an ion beam extracted from the ion source are accelerated. A high-frequency accelerating electrode; and a magnetic pole for generating a magnetic field formed so as to generate a circular orbit of the ion beam, wherein the discharge chamber and the magnetic path of the ion source have the magnetic pole in a vertical direction. When viewed from a cross-section, the magnetic pole is arranged inside the outer peripheral surface of the magnetic pole.

As another example, an ion source having at least a discharge chamber, a coil, and a magnetic path, and a high-frequency acceleration electrode for accelerating an ion beam extracted from the ion source are disposed so as to face each other, and a magnetic field is generated. A pair of magnetic poles formed in between, the magnetic pole has a depression on the opposite side of the surface facing the other magnetic pole, and the discharge chamber and the magnetic path of the ion source are the It is arranged in the recess of the magnetic pole.

According to the present invention, an external ion source type accelerator that can shorten the beam line and does not use a large-scale apparatus and a particle beam irradiation apparatus including the accelerator are provided.

It is a figure which shows the whole structure of the particle beam irradiation apparatus of Example 1 of this invention. It is a figure which shows the side surface cross section of the accelerator shown in FIG. It is a figure which shows the cross section of the accelerator shown in FIG. It is a figure which shows the outline of the side surface around the ion source of the accelerator of Example 1. FIG. It is a figure which shows the magnetic field analysis result of the ion source installation part in Example 1. FIG. It is a figure which shows the analysis result of the longitudinal magnetic field in the center position of the ion source installation part in Example 1. FIG. It is a figure which shows the cross section of the accelerator of Example 2 of this invention. It is a figure which shows the side surface cross section of the accelerator shown in FIG.

Embodiments of an accelerator and a particle beam irradiation apparatus according to the present invention will be described below with reference to the drawings.

<Example 1>
An accelerator and a particle beam irradiation apparatus according to a first embodiment of the present invention will be described with reference to FIGS. Initially, the whole structure of a particle beam irradiation apparatus and the structure of a related apparatus are demonstrated using FIG. FIG. 1 is a diagram showing the overall configuration of the particle beam irradiation apparatus of the present embodiment.

1, the particle beam irradiation apparatus 100 includes a cyclotron accelerator 50, a beam transport system 52, an irradiation apparatus 54, a treatment table 40, and a control apparatus 56.

In the particle beam irradiation apparatus 100, ions generated by the ion source 3 are accelerated by an accelerator 50 to be an ion beam. The accelerated ion beam is emitted from the accelerator 50 and transported to the irradiation device 54 by the beam transport system 52. The transported ion beam is shaped by the irradiation device 54 so as to match the shape of the affected area, and a predetermined amount is irradiated to the target of the patient 45 lying on the treatment table 40.

The operation of each device and equipment in the particle beam irradiation apparatus 100 including the accelerator 50 is controlled by the control device 56.

Next, the structure of the accelerator 50 will be described with reference to FIGS. FIG. 2 is a side sectional view of the accelerator of the present embodiment, and FIG. 3 is a transverse sectional view.

As shown in FIGS. 2 and 3, the cyclotron accelerator 50 includes a main magnetic pole 1, an annular coil 2, a vacuum vessel 6, a high-frequency acceleration electrode 7, an ion source 3, a beam extraction / focusing unit 4, and an inflector 5. Is done.

The main magnetic pole 1 is a pair of magnetic bodies installed so as to face each other, and is made of, for example, iron. The main magnetic pole 1 is provided with a convex magnetic pole 10 between the opposing magnetic poles so as to generate a circular orbit 9 of the beam, and an isochronous magnetic field is generated therebetween. The magnetic pole B0 is generated by the convex magnetic pole 10, and the focusing force of the circulating ion beam is increased, contributing to stable circulation. Opposing upper and lower surfaces between the magnetic pole gaps where the magnetic field B0 is generated are symmetrical.

The vacuum vessel 6 is sandwiched between the main poles 1 and forms a single vacuum vessel as a whole and constitutes a magnetic circuit. The vacuum vessel 6 is a nonmagnetic material.

The annular coil 2 is installed on the atmosphere side from the vacuum vessel 6 and generates a magnetic field between the pair of upper and lower main magnetic poles 1. The annular coil 2 can generate a magnetic field in the same manner whether it is a coil made of a normal conducting material or a coil made of a superconducting material. The annular coil 2 may be installed in the vacuum vessel 6 and is not particularly defined.

As shown in FIGS. 2 and 3, a depression 1B is formed on the outer peripheral surface 1A side opposite to the surface of the main magnetic pole 1 facing the other main magnetic pole 1, and the ion source 3 and the beam extraction and focusing section 4 are formed. Is disposed inside the recess 1B. That is, the main components constituting the ion source 3 and the beam extraction and focusing unit 4 are located inside the main magnetic pole 1 from the outer peripheral surface 1A and outside the convex magnetic pole 10 when the main magnetic pole 1 is viewed from the vertical cross section. Is arranged. Ions generated by the beam extraction and focusing unit 4 are extracted from the ion source 3. Details of the ion source 3 and the beam extraction focusing unit 4 will be described later.

Since the ion source 3 and the beam extraction and focusing unit 4 can be restrained from beam divergence by arranging them as close to the orbit 9 as possible, no other means for shaping the beam is required and the number of components is reduced. Can do.

Although the ion beam immediately after being extracted from the ion source 3 becomes a diverging beam, the vertical distance (mainly the convex magnetic pole 10) from the beam extraction unit 120 (see FIG. 4) of the beam extraction and focusing unit 4 to the inflector 5 is obtained. A set of focusing lenses 200 (see FIG. 4) is arranged according to the gap). Of the beam extraction / condensing unit 4, the converging lens 200 need not be provided when the vertical distance from the beam extraction unit 120 (see FIG. 4) to the inflector 5 is sufficiently small. Often it is sufficient, but two or more can be provided.

It should be noted that the ion source 3 and the beam extraction / condensing unit 4 can be arranged so as to be accommodated on the inner peripheral surface side of the main magnetic pole 1 in the depression provided in the lower main magnetic pole 1.

The ion beam extracted by the beam extraction and focusing section 4 is deflected from the vertical to the horizontal direction by the inflector 5 arranged at the center of the orbit 9. The inflector 5 is a device that deflects an ion beam using an electric field so as not to disturb the main magnetic field B0.

The ion beam deflected in the horizontal direction by the inflector 5 is accelerated by the high frequency acceleration electrode 7 and accelerated while drawing a spiral orbit 9 by the action of the magnetic field of the convex magnetic pole 10 and the electric field of the high frequency acceleration electrode 7. Is extracted from the orbit 9 and output to the outside.

Next, details of the ion source 3 and the beam extraction and focusing unit 4 will be described with reference to FIGS. FIG. 4 is a diagram showing details of the ion source 3 and the beam extraction and focusing unit 4 of FIG.

As shown in FIG. 4, the ion source 3 is a microwave ion source using a microwave 130 for plasma generation, and includes a waveguide 101, a magnetic path 103, a coil 102, a discharge chamber 105, an introduction window 109, and an extraction electrode 110. , Flange 111 and insulator 104. The ion source 3 is disposed on the inner side of the recess 1B formed on the outer peripheral surface 1A side of the main magnetic pole 1 as described above.

Of the ion source 3, the discharge chamber 105 and the portion of the magnetic path 103 that shields the discharge chamber 105 may be disposed inside the main magnetic pole 1. Is not necessarily arranged inside the main pole 1, but it is desirable that other configurations are also arranged inside the main pole 1.

The beam extraction focusing unit 4 includes a beam extraction unit 120 including a deceleration electrode 107, an insulator 106, and a ground electrode 108, and a focusing lens 200 including a lens electrode 201 and an exit hole 202.

In the ion source 3, the microwave 130 is introduced into the vacuum discharge chamber 105 from the waveguide 101 through the introduction window 109, and the source gas is introduced from the gas supply source (not shown), and the introduced gas is converted into the microwave. Plasma is generated by being ionized by an electric field and a magnetic field generated by the coil 102.

The waveguide 101 is a tube that supplies a microwave supplied from a microwave transmission source (not shown) to the inside of the ion source 3, and is made of iron. The waveguide 101 may be aluminum or copper, but is preferably made of iron because it is connected to the ion source 3 disposed inside the main magnetic pole 1.

The frequency of the microwave 130 is, for example, 2.45 GHz (GHz).

The introduction window 109 is made of an insulating material having a low dielectric constant so as to reduce the reflection of the microwave 130, and is made of, for example, quartz, boron nitride (BN), aluminum nitride, or the like.

The discharge chamber 105 is made of a non-magnetic metallic material, and the inner peripheral side is a vacuum where plasma is generated.

The coil 102 is disposed around the discharge chamber 105, and a magnetic path 103 is formed so as to surround the coil 102.

The magnetic path 103 is a magnetic body shaped to cover the discharge chamber 105 and is made of, for example, iron. This magnetic path 103 prevents the magnetic field leaking from the main pole 1 from affecting the discharge chamber 105.

The coil 102 can be adjusted independently, and the magnetic field generated in the discharge chamber 105 is adjusted. Although two coils 102 are used in FIG. 4, a magnetic field can be generated with one or three coils. In the case of one, the magnetic field distribution in the discharge chamber 105 can be adjusted by appropriately forming the shape of the magnetic path 103. The coil 102 can be replaced with a permanent magnet.

FIG. 5 shows a two-dimensional magnetic field analysis result when a space for installing the ion source 3 is provided in the main magnetic pole 1 and the magnetic path 103 and the coil 102 are installed therein. The current value of the annular coil 2 was determined and analyzed so that a magnetic field of about 1.3 Tesla (T) was generated in the gap between the magnetic poles of the main magnetic pole 1.

As shown in FIG. 5, since the magnetic field leaking from the main pole 1 flows into the magnetic path 103, it was found that the influence of the leaking magnetic field into the discharge chamber 105 can be reduced. For this reason, it has been found that the magnetic field generated by the coil 102 is sufficiently formed on the discharge chamber 105 side. Further, since the magnetic field leaking from the main magnetic pole 1 also flows into the waveguide 101, it has been found that the influence of the leakage magnetic field into the discharge chamber 105 can be further reduced by appropriately selecting the material of the waveguide 101.

FIG. 6 shows the magnetic field distribution at the position of the central portion 160 shown in FIG. The horizontal axis indicates the vertical position of the central portion 160, and the vertical axis indicates the vertical magnetic field strength at that position.

As shown in FIG. 6, when the ion source 3 is not arranged on the

main pole

1, 150 has a leakage magnetic field of several hundred gauss. On the other hand, when there is an ion source 3 having a magnetic path 103, the magnetic field in the discharge chamber 105 becomes close to zero. Further, in the case where a magnetic field for plasma generation is generated by the coil 102 in the ion source 3 having the magnetic path 103, a magnetic field having a gradient of cyclotron resonance magnetic field strength required for plasma generation of 0.0875 Tesla or more can be formed. I understand.

4, the insulator 104 insulates and supports the waveguide 101, the magnetic path 103, the coil 102, the discharge chamber 105, the introduction window 109, and the extraction electrode 110 in the ion source 3. The insulator 104 is not particularly limited as long as it is an insulating material.

The extraction electrode 110 is an electrode disposed at the lower part of the discharge chamber 105 and is a magnetic material. By making the extraction electrode 110 magnetic, the magnetic field distribution in the discharge chamber 105 can be easily made effective for plasma generation.

A positive voltage, for example, 30 to 60 kilovolts (kV) is applied to the flange 111 of the ion source 3 by the extraction power supply 300, and a negative voltage, for example, −2 to −10 kilovolts (kV) is applied to the deceleration electrode 107 by the deceleration power supply 301. ) Is applied. An ion beam is extracted from the plasma generated in the discharge chamber 105 by the electric field between the extraction electrode 110 and the deceleration electrode 107 generated by the extraction power source 300 and the deceleration power source 301.

The deceleration electrode 107 is disposed below the magnetic path 103, the coil 102, the discharge chamber 105 and the like that are insulated and supported by the insulator 104. The deceleration electrode 107 and the like are fixed to the ground electrode 108 by the insulator 106, and further, the main magnetic pole. 1 is fixed.

A focusing lens (beam focusing portion) 200 including a lens electrode 201 and an exit hole 202 is attached to the ground electrode 108 in the beam extraction direction. The focusing lens 200 focuses the ion beam extracted from the ion source 3. The beam extraction focusing unit 4 is formed by integrating the focusing lens 200, the ground electrode 108, the deceleration electrode 107, and the like.

A voltage is applied to the lens electrode 201 by a lens power source 302. The voltage is a positive value that does not exceed the voltage of the extraction power supply 300. By installing a plurality of lens electrodes 201 in the beam extraction direction and applying independent voltages to each other, the beam can be further shaped freely. The voltage may be applied by an independent power source or by a single power source by resistance division or the like.

The ion beam extracted from the ion source 3 is focused by a focusing lens 200 having a lens electrode 201 and taken out from an exit hole 202, and then the beam is projected between the convex magnetic poles 10 facing the main magnetic pole 1 by the inflector 5. Introduced into the gap.

By attaching the integrated beam extraction and focusing unit 4 immediately after the ion source 3, the beam can be focused before the ion beam extracted from the ion source 3 diverges, so that the voltage of the lens power supply 302 is kept low. Can also reduce the capacity of the power supply.

Next, the effect of this embodiment will be described.

The above-described particle beam irradiation apparatus 100 according to the first embodiment of the present invention includes the accelerator 50 and the irradiation apparatus 54 that irradiates the ion beam emitted from the accelerator 50. Among these, the accelerator 50 generates an ion source 3 having at least a discharge chamber 105, a coil 102, and a magnetic path 103, a high-frequency acceleration electrode 7 for accelerating an ion beam extracted from the ion source 3, and a beam orbit 9. And a pair of main magnetic poles 1 disposed so as to face each other. In such an accelerator 50, the main magnetic pole 1 has a recess 1B on the surface on the outer peripheral surface 1A side opposite to the surface facing the other main magnetic pole 1, and the discharge chamber 105 and the ion source 3 The magnetic path 103 is disposed inside the outer peripheral surface 1A of the main magnetic pole 1 when the main magnetic pole 1 is viewed from the vertical cross section, that is, is disposed in the recess 1B of the main magnetic pole 1.

With such a configuration, in the cyclotron accelerator 50 including the external ion source type ion source 3, the main configuration of the ion source 3 is arranged in the recess 1B on the inner side of the outer peripheral surface 1A of the main magnetic pole 1. Therefore, the beam line after extraction from the ion source 3 can be greatly shortened compared to the conventional external ion source type as described in Patent Document 1, although it is an external ion source type, so that it is complicated and large. It is possible to provide a small accelerator capable of reducing the number of components without using a simple device. Moreover, since it is an external ion source type, the effect that the access at the time of a maintenance, replacement | exchange, etc. is also easy is acquired.

Further, since the ion source 3 has the magnetic path 103 and the discharge chamber 105 and the magnetic path 103 are disposed in the recess 1B on the inner side of the outer peripheral surface 1A of the main magnetic pole 1, the ion source is provided in the main magnetic pole 1. Even when 3 is installed, the influence of the leakage magnetic field of the main magnetic pole 1 can be blocked. Therefore, it is possible to prevent a problem that has been found by the inventor's examination that the ion source cannot be sufficiently generated simply by disposing the ion source on the inner side of the outer peripheral surface 1A of the main magnetic pole 1.

Further, the main magnetic pole 1 has a convex magnetic pole 10, and since the discharge chamber 105 and the magnetic path 103 in the ion source 3 are arranged outside the convex magnetic pole 10, it is difficult to access during maintenance such as replacement. The arrangement of the ion source of the external ion source type that is easy to access without the arrangement close to the internal ion source type is more easily obtained, and the effect that the maintenance is easy while shortening the beam line is more reliably obtained. be able to.

Further, by providing at least one focusing lens 200 for focusing the ion beam extracted from the ion source 3, the beam can be focused even if the beam diverges after the beam is extracted from the ion source 3.

In addition, since the ion source 3 is a microwave ion source, it can be a long-life ion source, and further improvement in maintainability such as reduction in replacement frequency can be achieved.

Furthermore, since the waveguide 101 is further connected to the ion source 3 and the waveguide 101 is made of iron, the magnetic field generated by the coil 102 can be concentrated in the discharge chamber 105 and the main magnetic pole can be concentrated. 1 can further suppress the leakage magnetic field from entering the inside of the discharge chamber 105, and the ion generation efficiency in the ion source 3 can be improved.

As the accelerator 50, a synchrocyclotron accelerator that uses a magnetic field that is not an isochronous magnetic field can be used instead of the cyclotron accelerator that uses an isochronous magnetic field as described above.

The synchrocyclotron accelerator is a type of accelerator that is an improvement of the cyclotron. It accelerates repeatedly by applying a high-frequency electric field to charged particles that move circularly between large magnetic poles. At high speed, the mass of the accelerated particle increases due to relativistic effects, and the period of the circular motion of the charged particle in the magnetic field increases in proportion to the mass. The shift of the period from the high frequency voltage caused by this is removed by modulating the frequency.

Since the structure of the synchrocyclotron accelerator is the same as that of the cyclotron accelerator, the ion source 3 and the beam extraction / focusing section 4 can be arranged in the main magnetic pole 1 and the same effect can be obtained.

<Example 2>
An accelerator and a particle beam irradiation apparatus according to Embodiment 2 of the present invention will be described with reference to FIGS.

Since the particle beam therapy system of the present embodiment has the same structure as that of the particle beam therapy system of Example 1 except that the structure of the accelerator is different, the description other than the accelerator will be omitted. The structure of the accelerator 90 provided in the particle beam apparatus of the present embodiment will be described with reference to FIGS. FIG. 7 is a diagram showing a cross section of the accelerator, and FIG. 8 is a diagram showing a cross section AA of FIG.

As shown in FIGS. 7 and 8, the accelerator 90 according to the present embodiment includes an ion source 73, a high-frequency acceleration electrode 77, a main magnetic pole 71, a local magnetic field generator 83, a vacuum vessel 76, and an annular coil 72. And a take-out septum 81.

In the vacuum vessel 76, a high-frequency acceleration electrode 77 having a hollow inside is disposed symmetrically on the concave magnetic pole 80c so that a high-frequency power is applied from the outside by a high-frequency power source. Using the electric field generated by the high frequency, the high frequency acceleration electrode 77 accelerates the ion beam extracted from the ion source 73.

The vacuum vessel 76 is arranged so as to be sandwiched between the main magnetic poles 71, and forms a single vacuum vessel as a whole and forms a main magnetic field B0 in the magnetic pole gap by forming a magnetic circuit. The vacuum container 76 is a nonmagnetic material.

The annular coil 72 is installed on the atmosphere side of the vacuum vessel 76 and is a coil for causing the main magnetic pole 71 to generate the main magnetic field B0 in the magnetic pole gap between the main magnetic poles 71. The annular coil 72 may be a coil made of a normal conducting material or a coil made of a superconducting material.

As shown in FIG. 7, the main magnetic pole 71 has convex

magnetic poles

80a ₁ , 80a ₂ , 80b ₁ , 80b ₂ and a concave magnetic pole 80c. When viewed from the upper surface, the main magnetic pole 71 has a convex magnetic pole 80a ₁ and a convex magnetic pole 80a. ₂ and are symmetrical, and the convex pole 80b ₁ and the convex pole 80b ₂ has a structure symmetrical. In contrast, the convex pole 80a ₁ and the convex pole 80b ₁ and is vertically asymmetrical, and the convex pole 80a ₂ and the convex pole 80b ₂ has a structure Asymmetric. The circulating frequency of the ion beam is, for example, 19.82 megahertz (MHz), and the main magnetic pole 71 is set to generate an isochronous magnetic field that makes one round at the same time regardless of the energy. For example, the magnetic field acting on the beam along the beam trajectory is formed by the convex

magnetic poles

80a ₁ , 80a ₂ , 80b _{1, and} 80b _{2 so as} to be a low magnetic field in the concave portion and a high magnetic field in the convex portion. The shape and height of the convex

magnetic poles

80a ₁ , 80a ₂ , 80b ₁ , 80b ₂ are set to such an orientation and intensity as to suppress the divergence of the ion beam in the vertical direction and the circumferential direction. The main magnetic pole 71 is a magnetic material such as iron. The surface of the main magnetic pole 71 that faces the magnetic pole gap is symmetrical. The center of the magnetic pole formed by the convex

magnetic poles

80a ₁ , 80a ₂ , 80b ₁ , 80b ₂ , and the concave magnetic pole 80c is located at a position biased from the center of the main magnetic pole 71 to the beam extraction position 82, and the ion source 73 is arranged in the vicinity thereof. Has been. Due to such a biased arrangement structure, the main magnetic pole 71 generates a trajectory aggregation region 78 in the circular trajectory 79.

In this embodiment, four convex

magnetic poles

80a ₁ , 80a ₂ , 80b ₁ , 80b ₂ are used, but there is no limitation as long as the number is two or more. Although not shown, the convex

magnetic poles

80a ₁ , 80a ₂ , 80b ₁ , 80b ₂ are provided with trim coils for fine adjustment of the magnetic field so that the isochronism and the stability of the betatron oscillation are ensured. It is also possible to adjust.

As described above, the “isochronous magnetic field” in the present invention means that the ion beam makes one round even if the energy of the accelerated ion beam increases and the radius of the beam orbit around the ion beam increases. It means a magnetic field that does not change time.

Further, the “circular orbit” means a plurality of annular orbits until ions emitted from the ion source 73 are extracted from the extraction position 82.

As shown in FIG. 8, the ion source 73 is also formed in a recess 71B formed in the outer peripheral surface 71A of the main magnetic pole 71 when the main magnetic pole 71 is viewed from the vertical cross section, and in the convex

magnetic poles

80a ₁ , 80a ₂ , 80b. ₁ and 80b ₂ are arranged outside. In the ion source 73 as well, the discharge chamber and the portion of the magnetic path that shields the discharge chamber need only be disposed inside the main magnetic pole 71, and other configurations are not necessarily disposed inside the main magnetic pole 71. There is no need to be done.

Accelerator 90 configured as described above operates as follows.

The ion beam extracted from the ion source 73 by the beam extraction and converging unit 74 is deflected from the vertical to the horizontal direction by the inflector 75 disposed at the center of the circular orbit 79, and the convex

magnetic poles

80a ₁ , 80a ₂ , 80b ₁ , 80b ₂ , Helical motion is performed by the main magnetic field B0 formed by the concave magnetic pole 80c. Each time it passes through the high-frequency acceleration electrode 77 during the spiral motion, it is accelerated by the electric field generated at the high-frequency acceleration electrode 77, the energy is increased, and the rotation radius is increased to move around the vacuum vessel 76. At this time, the shape and height of the convex

magnetic poles

80a ₁ , 80a ₂ , 80b ₁ , 80b ₂ are set to such an orientation and intensity that suppress the divergence of the beam in the vertical direction and the circumferential direction, and the ion beam The energy is set to make one round in the same time. The magnetic field acting on the beam along the beam trajectory is a low magnetic field in the concave portion and a high magnetic field in the convex portion due to the convex

magnetic poles

80a ₁ , 80a ₂ , 80b ₁ , and 80b ₂ . In this way, the strength of the magnetic field along the beam trajectory is added, and the average value of the magnetic field along the trajectory is proportional to the relativistic gamma factor (γ factor) of the beam. The betatron oscillation is stably performed in the direction perpendicular to the orbital plane and the orbital plane of the beam.

The orbiting beam is deflected by the local magnetic field generated by the local magnetic field generator 83 that has reached the extraction energy. As a result, the orbiting beam deviates from the orbit, moves to the extraction position 82, and is guided out of the accelerator 90 by the extraction septum 81. The direction of the local magnetic field is determined by the energy in the same or opposite direction as the main magnetic field B0. Since the orbiting ion beam trajectory is gathered at the take-out position 82, deflection and take-out toward the take-out position 82 can be performed with a smaller local magnetic field compared to the trajectory that has not been gathered.

Other configurations / operations are substantially the same configurations / operations as the accelerator and particle beam irradiation apparatus of the first embodiment described above, and the details are omitted.

In the accelerator and the particle beam irradiation apparatus according to the second embodiment of the present invention, substantially the same effects as those of the accelerator and the particle beam irradiation apparatus according to the first embodiment described above can be obtained.

Further, since the main magnetic pole 71 is formed so as to generate the trajectory aggregation region 78 in the circular trajectory 79, the circulating ion beam trajectory is aggregated at the extraction position 82. The beam can be deflected to the beam extraction position 82 with a smaller local magnetic field, and the extraction is very easy. In particular, since the distance between the beam orbits is narrower than that in the conventional case in the orbital integration region 78, even if the energy of the ion beam is wide, a predetermined magnetic field can be obtained by using a magnetic field generated by the local magnetic field generation unit 83. The ion beam of energy can be deflected stably and easily toward the beam extraction position 82 on the trajectory aggregation region 78 side.

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

For example, in the above-described embodiment, the case where the microwave ion source is used as the ion source has been described, but the ion source is not limited to the microwave ion source. For example, the present invention can be applied to a direct current type or high frequency type ion source as long as a magnetic path is provided so as to shield the discharge chamber.

DESCRIPTION OF

SYMBOLS

1,71 ...

Main pole

1A, 71A ... Outer

peripheral surface

1B, 71B ...

Indentation

2, 72 ...

Toroidal coil

3, 73 ...

Ion source

4, 74 ... Beam

extraction focusing part

5, 75 ...

Inflector

6, 76 ...

Vacuum container

7,77 ...

RF acceleration electrodes

9,79 ... orbit _{_{_{10,80a 1, 80a 2, 80b 1}}} , 80b 2 ... protruding poles 40 ... treatment table 45 ...

patient

50, 90 ... accelerator 52 ... beam transport system 54 ... irradiation device 56 ... Control device 78 ... Orbit aggregation region 80c ... Concave magnetic pole 81 ... Extraction septum 82 ... Extraction position 83 ... Local magnetic field generator 100 ... Particle beam irradiation device 101 ... Waveguide 102 ... Coil 103 ... Magnetic path 104 ... Insulator 105 ... Discharge chamber 106 ... Insulator 107 ... Deceleration electrode 108 ... Ground electrode 109 ... Introduction window 110 ... Extraction electrode 111 ... Flange 120 ... Beam extraction part 130 ... My B wave 160 ... center 200 ... converging lens (beam focusing portion)
201 ... Lens electrode 202 ... Outlet hole 300 ... Drawer power supply 301 ... Deceleration power supply 302 ... Lens power supply

Claims

An ion source having at least a discharge chamber, a coil and a magnetic path;
A high-frequency acceleration electrode for accelerating an ion beam drawn from the ion source;
A magnetic pole for generating a magnetic field formed so as to generate a circular orbit of the ion beam,
Among the ion sources, the discharge chamber and the magnetic path are arranged on the inner side of the outer peripheral surface of the magnetic pole when the magnetic pole is viewed from a vertical cross section.
The accelerator according to claim 1,
The magnetic pole has a magnetic pole protrusion,
The accelerator characterized in that the discharge chamber and the magnetic path of the ion source are disposed outside the magnetic pole protrusion.
The accelerator according to claim 1,
The accelerator further includes at least one beam converging unit that focuses the ion beam extracted from the ion source.
The accelerator according to claim 1,
The accelerator is characterized in that the magnetic pole is formed so as to generate a trajectory aggregation region in the orbit.
The accelerator according to claim 1,
The accelerator is characterized in that the ion source is a microwave ion source.
The accelerator according to claim 5, wherein
The accelerator further comprising a waveguide connected to the ion source, wherein the waveguide is made of iron.
The accelerator according to claim 1,
The accelerator is a synchrocyclotron.
An accelerator according to claim 1;
An irradiation apparatus that irradiates the ion beam emitted from the accelerator. A particle beam irradiation apparatus, comprising:
An ion source having at least a discharge chamber, a coil and a magnetic path;
A high-frequency acceleration electrode for accelerating an ion beam drawn from the ion source;
A pair of magnetic poles that are installed to face each other and form a magnetic field therebetween,
The magnetic pole has a depression on the surface opposite to the surface facing the other magnetic pole,
The accelerator characterized in that the discharge chamber and the magnetic path of the ion source are arranged in the depression of the magnetic pole.