Superconducting magnet with iron core, accelerator having superconducting magnet with iron core, and particle beam medical treatment device having accelerator

Abstract

To enable support of devices in a predetermined space between magnetic poles while suppressing influence applied to a magnetic field distribution.SOLUTION: A superconducting magnet 11 with an iron core, comprises: a plurality of iron cores 12 and 13 that are provided so as to be opposite in a shaft direction, and can be divided in the shaft direction; a superconducting coil 23 that is provided on the circumference of each of magnetic poles 121 and 131 formed in a center part of each of the plurality of iron core parts; and at least one support member 100 that supports a device 200 provided in a predetermined space 16 between the magnetic poles from at least one of the magnetic poles. In the support member, a part 120 projecting to the predetermined space from each magnetic pole is formed of a non-magnetic material.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a superconducting magnet with an iron core, an accelerator equipped with a superconducting magnet with an iron core, and a particle beam therapy device equipped with an accelerator. [Background technology]

[0002] High-energy ion beams used in particle beam therapy, physical experiments, etc. are generated by using accelerators. Known accelerators that obtain beams with kinetic energy per nucleon of around 200 MeV include, for example, cyclotrons, synchrotrons, and synchrocyclotrons (Patent Document 1). Devices such as dee electrodes and dummy dee electrodes are attached to the magnetic poles. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2020-511170 Summary of the Invention [Problem to be solved by the invention]

[0004] In superconducting accelerators with an iron core, such as superconducting cyclotrons or superconducting synchrocyclotrons, various devices are installed between the magnetic poles. For this reason, it is necessary to attach support members between the magnetic poles to support the devices. However, when a strong support is required, such as when precise positioning is required, a hole is formed in the magnetic pole and a rod-shaped support member is inserted into the hole to install the device. If the support member is made of a magnetic material, the part that protrudes upward from the hole can cause an error magnetic field. In contrast, if the support member is made of a non-magnetic material, the part inserted into the hole can cause an error magnetic field.

[0005] Therefore, the present disclosure provides a superconducting magnet with an iron core that is capable of supporting equipment in a specified space between each magnetic pole while suppressing the effect on the magnetic field distribution, an accelerator equipped with a superconducting magnet with an iron core, and a particle beam therapy device equipped with an accelerator. [Means for solving the problem]

[0006] In order to solve the above problems, a superconducting magnet with an iron core according to the present invention comprises a plurality of iron core sections arranged opposite each other in the axial direction and capable of being divided in the axial direction, a superconducting coil arranged around each of the magnetic poles formed in the plurality of iron core sections, and at least one support member that supports, from at least one of the magnetic poles, an apparatus arranged in a specified space between the magnetic poles, wherein the portion of the support member protruding from the magnetic pole into the specified space is formed of a non-magnetic material. Effect of the Invention

[0007] According to the present invention, the portion of the support member that protrudes into the specified space between the magnetic poles is made of a non-magnetic material, so that the equipment can be supported in the specified space while suppressing the effect on the magnetic field distribution. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a side view of an accelerator having a superconducting magnet with an iron core. [Diagram 2] Plan view of the accelerator. [Diagram 3] Axial cross-sectional view of the accelerator. [Figure 4] 1 shows the accelerator at different cross sections and magnified views. [Diagram 5] FIG. 4 is an enlarged cross-sectional view of a support member. [Figure 6] FIG. 13 is an explanatory diagram showing a state in which the upper core portion is displaced upward. [Figure 7] FIG. 1 is a diagram showing the overall configuration of a particle beam therapy device that uses an accelerator. [Figure 8] FIG. 10 is an enlarged cross-sectional view of a support member according to a second embodiment. [Figure 9] 11 is an enlarged cross-sectional view of a support member according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, a superconducting magnet with an iron core and an accelerator equipped with the superconducting magnet with an iron core will be described with reference to the drawings. Furthermore, a particle beam therapy system equipped with the accelerator will also be described.

[0010] The present disclosure provides a superconducting magnet with an iron core that can suppress the generation of an error magnetic field relative to a predetermined magnetic field distribution even when a support member is installed on the magnetic pole. In the present disclosure, the support member placed on the magnetic pole is formed as a composite part in which a magnetic material and a non-magnetic material are joined together. The portion of the support member made of a magnetic material is inserted into a hole formed in the magnetic pole. The portion protruding from the hole is made of a non-magnetic material. In this way, according to the present disclosure, it is possible to suppress the generation of an error magnetic field relative to a predetermined magnetic field distribution.

[0011] In the present disclosure, the support member comprises a base end support portion that is provided within the magnetic pole and is made of a magnetic material, and a tip end support portion that protrudes from the magnetic pole into a predetermined space and is made of a non-magnetic material, and the base end support portion and the tip end support portion are integrated.

[0012] In the present disclosure, the base support is embedded in a hole formed in the magnetic pole.

[0013] In the present disclosure, a corrective magnetic body having a volume equivalent to the space on the bottom side of the hole into which the base end support part is not inserted is attached to the tip end support part.

[0014] In the present disclosure, the base end support portion protrudes into a predetermined space by an amount corresponding to the volume of the space on the bottom side of the hole portion into which the base end support portion is not inserted.

[0015] In this disclosure, each magnetic pole is formed to have a predetermined three-dimensional shape. EXAMPLES

[0016] Example 1 will be described with reference to Figures 1 to 6. Figure 1 is a side view of accelerator 10. Figure 2 is a plan view of accelerator 10. Figure 3 is an axial cross-sectional view of accelerator 10.

[0017] A total of four lifting members 40 may be provided on the outer periphery of the main electromagnet 11, spaced apart by 90 degrees, or a total of three lifting members 40 may be provided on the outer periphery of the main electromagnet 11, spaced apart by 120 degrees. Alternatively, five or more lifting members 40 may be provided on the outer periphery of the main electromagnet 11.

[0018] The accelerator 10 is, for example, a frequency-modulated variable energy accelerator. The accelerator 10 is a circular accelerator that has a time-constant magnetic field as a main magnetic field and accelerates ions (protons, carbon, etc.) circulating in the main magnetic field by a high-frequency electric field.

[0019] The accelerator 10 includes a radio frequency acceleration cavity 101 (see FIG. 7) that forms an accelerating electric field for accelerating ions, a rotary variable capacitor (not shown) for modulating the frequency of the accelerating electric field, an additional magnetic field generating shim (not shown) that gives a kicking action from a stable region to ions orbiting by a magnetic field formed by magnetic poles 121 and 131 (see FIG. 3), a disturbance electrode (not shown) that generates a disturbance electric field for taking out the ions kicked by the additional magnetic field generating shim from the accelerator 1, a low-level radio frequency generator (not shown) that controls the accelerating electric field, and a disturbance radio frequency controller (not shown) that controls the disturbance electric field. The accelerator 10 has an area where the circular orbits of a plurality of ions orbiting with different energies are concentrated and an area where they are separated, and ions injected in different cycles orbit at approximately the same energy at the same time.

[0020] The main electromagnet 11 of the accelerator 10 is provided with a plurality of refrigerator ports 30 and a plurality of lifting members 40. A plurality of (e.g., two) refrigerator ports 30 are provided on each of the upper and lower surfaces of the main electromagnet 11. As described above, a plurality of lifting members 40 are provided spaced apart on the outer periphery of the main electromagnet 11. A plurality of support legs 50 are provided on the lower surface side of the main electromagnet 11. The main electromagnet 11 is supported by the support legs 50 on a floor (not shown).

[0021] The main electromagnet 11 of the accelerator 10 includes, for example, an upper core portion 12 located on the axial upper side and a lower core portion 13 located on the axial lower side. The upper core portion 12 and the lower core portion 13 are provided facing each other in the axial (up-down) direction and can be separated in the axial direction. A division line 14 is formed between the upper core portion 12 and the lower core portion 13. As will be described later with reference to FIG. 6, by pulling the upper core portion 12 away from the lower core portion 13 and displacing it upward, an opening appears in the main electromagnet 11 along the division line 14. A worker can perform maintenance work on the equipment inside the main electromagnet 11 through the opening.

[0022] Maintenance work may include, for example, measuring the magnetic field inside the main electromagnet 11, adjusting magnetic field correction equipment (not shown) based on the results of the magnetic field measurement, and inspecting or replacing equipment (not shown) such as a high-frequency kicker.

[0023] As shown in FIG. 3, magnetic poles 121, 131 facing each other vertically are provided in the center of the main electromagnet 11. The magnetic pole 121 is provided in the center of the lower surface of the upper core portion 12, and another magnetic pole 131 is provided in the center of the upper surface of the lower core portion 13. A predetermined main magnetic field is generated by these magnetic poles 121, 131. The magnetic poles 121, 131 are formed in a predetermined three-dimensional shape. The three-dimensional shape here means that the entire surface is not formed flat, but has curved portions and is a shape more complicated than a flat surface. The three-dimensional shape may include a partially flat surface.

[0024] The space between the magnetic poles 121, 131 is a beam passing region 16 in which the ion beam circulates. The beam passing region 16 corresponds to the "predetermined space". The superconducting coil (main coil) 23 is provided along the inner walls of the upper core portion 12 and the lower core portion 13 so as to surround the magnetic poles 121, 131.

[0025] More specifically, an upper superconducting coil 23 is provided on the inner circumferential surface of the upper core portion 12 so as to surround the outside of the magnetic pole 121. A lower superconducting coil 23 is provided on the inner circumferential surface of the lower core portion 13 so as to surround the outside of the magnetic pole 131. Each superconducting coil 23 is attached to and supported by the coil frame 22.

[0026] The outside of the coil frame 22 is surrounded by a coil section shield plate 21. A shield plate surrounding a refrigerator port 30 provided on the upper side of the main electromagnet 11 is connected to the upper side of the coil section shield plate 21. A shield plate surrounding a refrigerator port 30 provided on the lower side of the main electromagnet 11 is connected to the lower side of the coil section shield plate 21. The shield plate 21 suppresses the transfer of heat from the outside to the superconducting coil 23 inside the shield plate 21.

[0027] The superconducting coil 23, the coil frame 22, and the coil shield plate 21 are provided inside the coil vacuum vessel 20. The coil vacuum vessel 20 is also called a cryostat. The coil vacuum vessel 20 maintains the vacuum and temperature inside. The temperature inside the coil vacuum vessel 20 is maintained by the cooling capacity of each refrigerator port 30.

[0028] The inside of the main electromagnet 11 is evacuated by a vacuum pump (not shown). The main electromagnet 11 is provided with a plurality of through-holes for connecting the outside with the beam passing region 16. For example, a beam extraction through-hole (not shown) for extracting an accelerated beam and a beam monitor mounting hole (not shown) for mounting a beam monitor are provided in the middle part 14 of the main electromagnet 11. In addition, a through-hole for extracting the coil conductor of the superconducting coil 23 to the outside and a through-hole for inputting high-frequency power to the acceleration electrode (neither of which are shown) are provided in the middle part of the main electromagnet 11.

[0029] The lifting member 40 will be described. A plurality of lifting members 40 are provided around the main electromagnet 11, and the lower side of the main body is attached to the outer circumferential surface of the lower core portion 13. The lifting member 40 may be of an electric type, hydraulic type, or pneumatic type. The tip of the rod 41 of the lifting member 40 is attached to the outer circumferential surface of the upper core portion 12. The lifting member 40 can displace only the upper core portion 12 axially upward of the main electromagnet 11 by extending the rod 41. The lifting member 40 can place the upper core portion 12 on the lower core portion 13 by contracting the rod 41. The lifting member 40 operates according to a control signal from a control device (not shown). The above-mentioned cryogenic refrigerator (refrigerator port 30) also operates according to a control signal from a control device (not shown).

[0030] Fig. 4 is a diagram showing the accelerator 10 in a different cross section. In the beam passing region 16 formed between the magnetic poles 121 and 131, devices 200 such as Dee electrodes, iron pieces for adjusting the magnetic field, and an ion source are installed. Fig. 4 shows as if only one device 200 is installed, but in reality, a plurality of devices 200 are installed. The device 200 can also be called a supported member.

[0031] The device 200 is supported from either one or both of the magnetic poles 121, 131 by at least one support member 100. Fig. 4 shows a case where the device 200 is supported by a plurality of support members 100 from both of the magnetic poles 121, 131, but is not limited to this. The device may be supported by a support member 100 provided on the lower magnetic pole 131, or may be supported by a support member 100 provided on the upper magnetic pole 121. A plurality of devices 200 supported in different directions are arranged in the beam passing region 16 (not shown).

[0032] The installation position of the device 200 is not limited to the central part in the axial direction of the beam passing region 16, and may be biased to either the upper or lower side. The support member 100 is provided at any location necessary for supporting the device 200 among the surfaces of the magnetic poles 121 and 131 having a three-dimensional shape. The location where the support member 100 is provided may be a curved surface or a flat surface.

[0033] The support member 100 has a portion (120) that protrudes from the magnetic pole into the beam passing region 16, which is the "predetermined space", made of a non-magnetic material. In detail, the support member 100 includes a base end support part 110 that is provided within the magnetic pole and made of a magnetic material, and a tip end support part 120 that protrudes from the magnetic pole into the beam passing region 16 and is made of a non-magnetic material. Examples of non-magnetic materials include SUS316 and SUS304.

[0034] 5, the base end support part 110 and the tip end support part 120 are integrated together. For example, the tip end side 113 of the head part 111 of the base end support part 110 and the base end side 123 of the first part 121 of the tip end support part 120 are firmly connected together using a fixing technique such as friction welding, explosive bonding, or HIP (Hot Isostatic Pressing).

[0035] The base end support part 110 is formed of a magnetic material such as pure iron. The base end support part 110 may be formed of the same magnetic material as the magnetic poles, or may be formed of a different magnetic material. The base end support part 110 is formed of a magnetic material in the shape of a bolt. The base end support part 110 has a head part 111 and a threaded part 112.

[0036] The magnetic pole is formed with a hole 115 in the axial direction through which the base end support part 110 is inserted. The hole 115 is a bolt insertion hole, and a substantially conical space 116 is formed at the bottom of the hole 115. The space 116 corresponds to a "bottom side space" into which the screw part 112 is not inserted. The side of the hole 115 facing the bottom space 116 is an opening 117 that opens on the surface of the magnetic pole. The support member 100 is firmly and detachably fixed to the magnetic pole by inserting and screwing the base end support part 110 into the hole 115. The support member 100 can also be removed from the magnetic pole for maintenance and replacement. The hole 115 from which the support member 100 has been removed can be plugged by inserting something like a screw plug made of a magnetic material that corresponds to the base end support part 110.

[0037] In other words, the base-end support part 110 is detachably fitted or screwed into the hole part 115. If there is no need to remove the support member 100 from the magnetic pole, the base-end support part 110 can be attached to the hole part 115 so as not to be detachable.

[0038] The tip side support part 120 is integrated with the base side support part 110 and protrudes into the beam passing region 16 to support the device 200. The tip side support part 120 includes, for example, a large-diameter first part 121 connected to the base side support part 110 and a small-diameter second part 122 protruding from the first part 121, and a tip side 124 of the second part 122 is in contact with the device 200. The relationship between the diameter of the first part 121 and the diameter of the second part 122 may be reversed. The cross-sectional shapes of the first part 121 and the second part 122 are not limited to a circular shape, and may be rectangular, polygonal, elliptical, or the like. The cross-sectional shapes of the first part 121 and the second part 122 may be similar to each other or different from each other.

[0039] 6 shows a schematic diagram of the state in which the upper core portion 12 has been displaced upward. When the connection between the upper core portion 12 and the lower core portion 13 is released and the rods 41 of each lifting member 40 are extended, the upper core portion 12 moves upward. When the upper core portion 12 is displaced upward, the upper side of the coil portion vacuum vessel 20 is exposed. This enables an operator to perform maintenance on the equipment 200, measure the magnetic force, set the magnetic force adjustment device, and so on.

[0040] 7 is a diagram showing the overall configuration of a particle beam therapy system 1 that uses an accelerator 10. The particle beam therapy system 1 includes the accelerator 10, a beam transport system 2, an irradiation device 3, a treatment table 4, an overall control device 5, an irradiation control device 6, a treatment plan database 7, and a treatment planning device 8.

[0041] The radio frequency acceleration cavity 101 forms an accelerating electric field for accelerating ions into an ion beam through a radio frequency power input through hole (not shown). The radio frequency acceleration cavity 101 is equipped with, for example, a dee electrode for acceleration and a rotary variable capacitor for modulating the frequency of the accelerating electric field (both not shown).

[0042] An ion source 103 for supplying hydrogen ions is installed at a position offset from the center above the main electromagnet 11. The ion source 103 supplies ions to a beam passing region 16 inside the accelerator 10 through a beam injection through-hole (not shown).

[0043] The beam transport system 2 is a mechanism that transports the ion beam accelerated by the accelerator 10 to the irradiation device 3. The irradiation device 3 is a device that irradiates the beam transported by the beam transport system 2 to a target inside a patient PT fixed to a treatment table 4. An overall control device 5 controls the accelerator 10, the beam transport system 2, and the irradiation device 3. An irradiation control device 6 controls the beam irradiation to the target. A treatment plan database 7 stores treatment plans created by a treatment planning device 8. The treatment planning device 8 creates a beam irradiation plan for the target.

[0044] In the particle beam therapy device 1, the energy and dose of the particle beam to be irradiated are determined by a treatment plan. The energy and dose of the particle beam determined by the treatment plan are input sequentially from the overall control device 5 to the irradiation control device 6. When the particle beam therapy device 1 irradiates the target with an appropriate dose, it moves to the next energy and irradiates the beam to the target again.

[0045] According to the particle beam therapy system 1 configured in this manner, since it includes the above-mentioned accelerator 10, it is possible to suppress the occurrence of an error magnetic field, and it is possible to further improve reliability.

[0046] According to the present disclosure, the base end side of the support member 100 can be attached to the magnetic pole, and therefore the device 200 can be supported. The support member 100 can firmly support the device 200 because the base end support part 110 is inserted into and fixed to the hole part 115 formed in the magnetic pole.

[0047] Since the base end support portion 110 of the support member 100 is formed from the same magnetic material as the material of the magnetic poles, loss of the iron core by the volume of the hole 115 is suppressed, and the generation of an error magnetic field can be reduced.

[0048] The tip side support part 120 of the support member 100 is made of a non-magnetic material, so that even if the tip side support part 120 protrudes into the beam passing region 16, it is possible to prevent it from causing an error magnetic field. EXAMPLES

[0049] Example 2 will be described with reference to Fig. 8. In the following examples including this example, differences from Example 1 will be mainly described. In the support member 100A of Example 2, a corrective magnetic body 130 having a volume equivalent to a bottom side space 116 of the hole 115 into which the base end support part 110 is not inserted is attached to the tip end support part 120.

[0050] The corrective magnetic body 130 is formed as, for example, an annular member such as a washer, and is attached to the outer periphery or step portion of the lower side of the first portion 121 of the tip side support part 120. By bringing the surface of the magnetic pole and the corrective magnetic body 130 as close as possible, the generation of the error magnetic field can be further suppressed.

[0051] The present embodiment thus configured also achieves the same effects as those of embodiment 1. Furthermore, in this embodiment, the corrective magnetic body 130 having a volume corresponding to the volume of the bottom space 116 of the hole 115 that is not filled by the base end support part 110 made of a magnetic material is provided in the tip end support part 120, so that the generation of an error magnetic field can be suppressed. Note that the volume of the corrective magnetic body 130 and the volume of the bottom space 116 do not need to be strictly the same. EXAMPLES

[0052] Example 3 will be described with reference to Fig. 9. In the support member 100B of this example, the head 111B of the base-end support part 110B protrudes into a predetermined space 16 by a predetermined amount H1, which is a volume equivalent to a bottom-side space 116 of the hole 115 into which the base-end support part 110B is not inserted.

[0053] The present embodiment configured in this manner also achieves the same effects as those of the embodiments 1 and 2. Furthermore, in the present embodiment, the head 111B of the base end support portion 110B is protruded into the beam passing area 16 by a predetermined amount H1 without using the corrective magnetic body 130, so that the number of parts can be reduced compared to the embodiment 2.

[0054] The present invention is not limited to the above-described embodiment. A person skilled in the art can make various additions and modifications within the scope of the present invention. The above-described embodiment is not limited to the configuration example shown in the attached drawings. The configuration and processing method of the embodiment can be appropriately changed within the scope of achieving the object of the present invention. For example, the shape of the refrigerator port installation area is not limited to the one shown in the drawings.

[0055] In addition, each component of the present invention can be selected arbitrarily, and the invention having the selected configuration is also included in the present invention. Furthermore, the configurations described in the claims can be combined in combinations other than those explicitly stated in the claims. [Explanation of symbols]

[0056] 1: particle beam therapy device, 2: beam transport system, 3: irradiation device, 4: treatment table, 5: overall control device, 6: irradiation control device, 7: treatment plan database, 8: treatment plan device, 10: accelerator, 11: main electromagnet, 12: upper core section, 13: lower core section, 14: dividing line, 16: beam passing area, 20: coil section vacuum vessel, 23: superconducting coil, 30: refrigerator port, 40: lifting member, 100, 100A, 100B: support member, 110, 110B: base end support section 110, 115: hole section, 116: space on bottom side, 120: tip end support section, 130: correction magnetic body, 200: equipment

Claims

1. A superconducting magnet with an iron core, A plurality of core portions that are disposed opposite to each other in an axial direction and that can be separated in the axial direction; a superconducting coil provided around each of the magnetic poles formed in the plurality of iron core portions; At least one support member that supports a device provided in a predetermined space between the magnetic poles from at least one of the magnetic poles; Equipped with The support member has a portion that protrudes from the magnetic pole into the predetermined space and is made of a non-magnetic material. A superconducting magnet with an iron core.

2. the support member includes a base end support portion provided within the magnetic pole and made of a magnetic material, and a tip end support portion provided protruding from the magnetic pole into the predetermined space and made of a non-magnetic material, The base end support portion and the tip end support portion are integrated together.

2. The superconducting magnet with an iron core according to claim 1.

3. The base end support portion is embedded in a hole formed in the magnetic pole.

3. The superconducting magnet with an iron core according to claim 2.

4. A correction magnetic body having a volume equivalent to the bottom side space of the hole into which the base end support part is not inserted is attached to the tip end support part.

4. The superconducting magnet according to claim 3.

5. The base end support portion is protruded into the predetermined space by an amount corresponding to a volume of a bottom side space of the hole portion into which the base end support portion is not inserted.

4. The superconducting magnet according to claim 3.

6. Each of the magnetic poles is formed to have a predetermined three-dimensional shape.

2. The superconducting magnet according to claim 1.

7. An accelerator comprising the superconducting magnet with an iron core according to any one of claims 1 to 6.

8. an irradiation device for irradiating a target with a beam accelerated by the accelerator according to claim 7; A control device for controlling the accelerator and the irradiation device; Equipped Particle beam therapy equipment.

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