JP2022147237A - Scanning Electromagnet Device and Charged Particle Beam Irradiation System - Google Patents

Abstract

To ensure a wider irradiation field of a beam irradiation device by increasing the generated magnetic field intensity without increasing the number of turns of a conductor forming a scanning coil.SOLUTION: Provided is a scanning electromagnet device, including X-direction scanning coils 21A, 21B or Y-direction scanning coils 22A, 22B that scan a charged particle beam 1 with the charged particle beam 1 deflected in an X direction or Y direction orthogonal to an incident direction (S direction) of the charged particle beam. The scanning coils are disposed opposite a direction orthogonal to the incident direction and beam deflection direction (X direction or Y direction), with a trajectory direction 3 of the charged particle beam put therebetween. The scanning coils have larger aperture along the incident direction in downstream than in upstream. Each scanning coil has aperture angles α, β in a cross-section perpendicular to the incident direction set larger downstream than upstream along the incident direction.SELECTED DRAWING: Figure 3

Description

An embodiment of the present invention relates to a scanning electromagnet device for scanning a charged particle beam, and a charged particle beam irradiation system having a beam irradiation device including this scanning electromagnet device.

In the treatment of irradiating a charged particle beam such as a heavy particle beam to the affected area (irradiation target) of a patient such as cancer, a charged particle beam generated by a beam generator is accelerated by a beam accelerator, and this charged particle beam is transported by beam transportation. After passing through the equipment, the affected area is irradiated by the beam irradiation equipment in the treatment room.

As one of the charged particle beam irradiation methods, there is a scanning method in which a narrow spot beam is irradiated so as to three-dimensionally fill in the affected area, which is the irradiation target, according to the three-dimensional shape. In this scanning method, the irradiation position in the beam incidence direction is controlled by the beam energy of the charged particle beam, and the irradiation position in the plane perpendicular to the beam incidence direction is controlled by deflecting the charged particle beam using a scanning electromagnet device. controlled. The scanning electromagnet device consists of two sets of a horizontal scanning electromagnet device and a vertical scanning electromagnet device. A system is known in which each scanning electromagnet device is arranged in series or in parallel (at the same position in the beam incident direction) and the charged particle beam is scanned in two orthogonal directions.

Japanese Unexamined Patent Application Publication No. 2018-20163 JP 2016-83344 A

In order to irradiate charged particle beams to various sites and cancerous areas of different sizes, it is desirable to ensure a wide irradiation area (irradiation field). In order to widen the irradiation field, it is desirable to bring the scanning coil of the scanning electromagnet device closer to the charged particle beam to increase the strength of the magnetic field acting on the charged particle beam.

Therefore, in a scanning electromagnet device in which a horizontal scanning electromagnet device and a vertical scanning electromagnet device are arranged in parallel, the aperture is reduced in the upstream portion before the charged particle beam is scanned, and the charged particle beam spreads as it is scanned. It is desirable to increase the aperture along the beam trajectory downstream where it becomes slanted. On the other hand, since the diameter of the downstream portion is large, the magnetic field intensity acting on the charged particle beam is smaller than that of the upstream portion, and sufficient deflection of the charged particle beam cannot be obtained. It may not be possible to secure a sufficient irradiation field.

The embodiments of the present invention have been made in consideration of the above-mentioned circumstances. It is an object of the present invention to provide a scanning electromagnet device capable of ensuring a wide range of , and a charged particle beam irradiation system having a beam irradiation device equipped with this scanning electromagnet device.

A scanning electromagnet device according to an embodiment of the present invention includes a scanning coil that deflects and scans the charged particle beam in a first direction orthogonal to an incident direction of the charged particle beam, and the scanning coil is configured to scan the charged particle beam. A plurality of scanning coils are arranged to face each other in a second direction orthogonal to the incident direction and the first direction, with the orbital position of , and these scanning coils have a diameter along the incident direction that is downstream of that on the upstream side. Each of the scanning coils is formed by winding a conductor, and an aperture angle, which is an angle between one end position of the conductor in a cross section perpendicular to the incident direction and the second direction, is It is characterized in that it is set larger on the downstream side than on the upstream side along the incident direction.

A charged particle beam irradiation system according to an embodiment of the present invention has a beam irradiation device including the scanning electromagnet device according to the embodiment of the invention, and the beam irradiation device deflects a charged particle beam using the scanning electromagnet device. It is characterized in that it is configured to scan and irradiate an object to be irradiated.

According to the embodiments of the present invention, it is possible to secure a wide irradiation field of the beam irradiation device by increasing the generated magnetic field intensity without increasing the number of turns of the conductor forming the scanning coil.

1 is a block diagram showing a charged particle beam irradiation system having a beam irradiation device equipped with a scanning electromagnet device according to a first embodiment; FIG. FIG. 2 is a block diagram showing the beam irradiation device in FIG. 1; 3(A) is a plan view, and (B) and (C) are sectional views along lines IIIB-IIIB and IIIC-IIIC of FIG. 3(A), respectively, showing the scanning electromagnet device of FIG. 4(A) is a plan view, and (B) and (C) are cross-sectional views along lines IVB-IVB and IVC-IVC of FIG. 4(A), respectively, showing the X-direction scanning electromagnet device of FIG. 5(A) is a plan view, and (B) and (C) are cross-sectional views taken along line VB--VB and line VC--VC of FIG. 5(A), respectively, showing the Y-direction scanning electromagnet device of FIG. Sectional drawing which shows FIG.4(C) typically. Sectional drawing which shows FIG.5(C) typically. FIG. 4B is a cross-sectional view showing a part of the scanning electromagnet device according to the second embodiment and corresponding to a cross section taken along line MM in FIG. 4A; FIG. 9 is a perspective view showing the litz wire of FIG. 8; FIG. 10 is a perspective view showing a hollow conductor as a comparative form to the litz wire of FIG. 9; Sectional drawing which shows a part of scanning electromagnet apparatus which concerns on 3rd Embodiment. 12(A) is a plan view, and (B) and (C) are cross-sectional views taken along line XIIB-XIIB and line XIIC-XIIC of FIG. 12(A), respectively, showing a conventional X-direction scanning electromagnet device.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated based on drawing.
[A] First embodiment (Figs. 1 to 7)
FIG. 1 is a configuration diagram showing a charged particle beam irradiation system having a beam irradiation device equipped with a scanning electromagnet device according to the first embodiment. The charged particle beam irradiation system 10 shown in FIG. 1 is an irradiation system that uses, for example, negative pions, protons, helium ions, carbon ions, neon ions, silicon ions, or argon ions as the charged particle beam 1 for therapeutic irradiation. . This charged particle beam irradiation system 10 has a beam generator 11, a vacuum duct 11A, a beam accelerator 12, a beam transporter 13, and a beam irradiation device 14. to irradiate.

The beam generation device 11 is a device that generates the charged particle beam 1, and includes, for example, a device that extracts ions generated using an electromagnetic wave, a laser, or the like. Further, the vacuum duct 11A is maintained in a vacuum state inside, and allows the charged particle beam 1 to pass through it, thereby suppressing beam loss due to scattering between the charged particle beam 1 and the air. As shown in FIGS. 1 and 2, the vacuum duct 11A extends from the beam generator 11 to just before the position of the patient to be irradiated.

The beam accelerator 12 is a device that accelerates the charged particle beam 1 to a predetermined energy. An example of the beam accelerator 12 is composed of two stages, a front-stage accelerator and a rear-stage accelerator (not shown). There are examples in which the front-stage accelerator is a linear accelerator (drift tube linac DTL or high-frequency quadrupole linear accelerator RFQ), and the rear-stage accelerator is a synchrotron or a cyclotron.

Specifically, the beam accelerator 12 includes a beam duct (piping) (not shown) for keeping a space through which the charged particle beam 1 passes in a vacuum-tight manner, a high-frequency acceleration cavity (not shown) for accelerating the charged particle beam 1 by an electric field, a charged particle It consists of a deflection device (dipole electromagnet) for stably guiding the beam 1, a beam convergence/divergence device (quadrupole electromagnet), a beam trajectory correction device (steering electromagnet), and their control devices, all of which are not shown.

The beam transport device 13 transports the accelerated charged particle beam 1 to the beam irradiation device 14 installed in the treatment room. It consists of correction devices and their control devices.

The beam irradiation device 14 is provided downstream of the beam transport device 13 . This beam irradiation device 14 adjusts the trajectory of the charged particle beam 1 so that the charged particle beam 1 of specific energy that has passed through the beam transport device 13 is correctly irradiated onto the irradiation point of the irradiation target 2, and The irradiation position and irradiation dose of the charged particle beam 1 are monitored. As shown in FIG. 2, the beam irradiation device 14 includes an X-direction scanning electromagnet device 15, a Y-direction scanning electromagnet device 16, a scanning electromagnet power supply 17, a position monitor 18A, a dosimeter 18B and a control device 19. be.

The X-direction scanning electromagnet device 15 and the Y-direction scanning electromagnet device 16 are arranged at the same position along the incident direction (S direction) of the charged particle beam 1 to constitute a scanning electromagnet device 20 . In this case, the Y-direction scanning electromagnet device 16 is arranged outside or inside the X-direction scanning electromagnet device 15, outside in the first embodiment.

As will be described in detail later, the X-direction scanning electromagnet device 15 moves the trajectory of the charged particle beam 1 in a first direction perpendicular to the incident direction (S direction) of the charged particle beam 1 (X direction in this X-direction scanning electromagnet device 15). direction (e.g., horizontal) to adjust and scan. The Y-direction scanning electromagnet device 16 moves the trajectory of the charged particle beam 1 in a second direction (this The Y-direction scanning electromagnet device 16 deflects, adjusts, and scans in the Y direction (for example, the vertical direction).

A scanning electromagnet power supply 17 supplies an excitation current necessary for scanning the charged particle beam 1 to the X-direction scanning electromagnet device 15 and the Y-direction scanning electromagnet device 16 . The position monitor 18A also outputs to the control device 19 a signal that serves as an index of the position of the charged particle beam 1 that has passed through the position monitor 18A, that is, the irradiation position of the charged particle beam 1 on the irradiation target 2 . Furthermore, the dosimeter 18B outputs to the controller 19 a signal corresponding to the intensity or dose of the charged particle beam 1 that has passed through the dosimeter 18B.

The controller 19 controls the scanning electromagnet power supply 17 so that the charged particle beam 1 emitted from the scanning electromagnet device 20 is applied to a predetermined position on the irradiation target 2 based on both signals from the position monitor 18A and the dosimeter 18B. As a result, the value of the excitation current supplied to the X-direction scanning electromagnet device 15 and the Y-direction scanning electromagnet device 16 is controlled.

As shown in FIGS. 3 and 4, the X-direction scanning electromagnet device 15 is constructed by arranging a pair of X-direction scanning coils 21A and 21B facing each other on the outer surface of a structure 23 as a coil support. . The structure 23 is made of non-metal that does not generate eddy current, such as FRP (Fiber-Reinforced Plastic), and holds the X-direction scanning coils 21A and 21B at predetermined positions on the outer surface.

The structure 23 has a hollow shape, and the aperture along the incident direction (S direction) of the charged particle beam 1 is larger on the downstream side than on the upstream side. be. Therefore, the X-direction scanning coils 21A and 21B held on the outer surface of the structure 23 also have diameters along the incident direction (S direction) of the charged particle beam 1 larger on the downstream side than on the upstream side. It is provided to continuously and gradually increase downstream. Further, the structure 23 is seamlessly formed along the incident direction (S direction) of the charged particle beam 1 .

The X-direction scanning coils 21A and 21B are arranged to face each other in the Y-direction (for example, the vertical direction) perpendicular to the S-direction and the X-direction, with the orbital position 3 of the charged particle beam 1 interposed therebetween. Of these, the X-direction scanning coil 21A includes a coil element 21A1 provided on the innermost side, a coil element 21A2 provided on the outer side of the coil element 21A1, and a coil element 21A3 provided on the outer side of the coil element 21A2. , The X-direction scanning coil 21B includes an innermost coil element 21B1, a coil element 21B2 provided outside the coil element 21B1, a coil element 21B3 provided outside the coil element 21B2, is configured with

Each of the coil elements 21A1, 21A2, 21A3, 21B1, 21B2 and 21B3 described above is configured by winding a plurality of conductors 24 in a saddle shape. An excitation current is supplied from the scanning electromagnet power supply 17 to these coil elements 21A1, 21A2, 21A3, 21B1, 21B2 and 21B3, whereby a Y-direction magnetic field By is formed in the X-direction scanning electromagnet device 15, and this magnetic field By , the charged particle beam 1 is deflected in the X direction and scanned. Although each of the X-direction scanning coils 21A and 21B is composed of three coil elements, it may be composed of one, two, or four or more coil elements.

As shown in FIGS. 3 and 5, the Y-direction scanning electromagnet device 16 is constructed by arranging a pair of Y-direction scanning coils 22A and 22B on the outer surface of the structure 25 so as to face each other. These Y-direction scanning coils 22A and 22B are arranged to face each other in the X-direction (for example, the horizontal direction) perpendicular to the S-direction and the Y-direction, with the orbital position 3 of the charged particle beam 1 interposed therebetween. The structure 25 is made of non-metal that does not generate eddy current, such as FRP (Fiber-Reinforced Plastic), and holds the Y-direction scanning coils 22A and 22B at predetermined positions on the outer surface.

The structure 25 has a hollow shape, and the aperture along the incident direction (S direction) of the charged particle beam 1 is larger on the downstream side than on the upstream side. be. Therefore, the Y-direction scanning coils 22A and 22B are also held at predetermined positions on the outer surface of the structure 25, so that the aperture along the incident direction (S direction) of the charged particle beam 1 is larger on the downstream side than on the upstream side. , that is, provided to continuously and gradually increase from the upstream side to the downstream side.

Further, the structure 25 has a split surface 26 parallel to the incident direction (S direction) of the charged particle beam 1, and is formed in a half-split shape that can be split in the Y direction. Thereby, the structure 25 includes the X-direction scanning electromagnet device 15 (the structure 23 and the X-direction scanning coils 21A and 21B) inside.

The Y-direction scanning coil 22A has an innermost coil element 22A1, a coil element 22A2 provided outside the coil element 22A1, and a coil element 22A3 provided outside the coil element 22A2. configured as The Y-direction scanning coil 22B includes an innermost coil element 22B1, a coil element 22B2 provided outside the coil element 22B1, a coil element 22B3 provided outside the coil element 22B2, is configured with

Each of the coil elements 22A1, 22A2, 22A3, 22B1, 22B2 and 22B3 described above is configured by winding a plurality of conductors 24 in a saddle shape. An excitation current is supplied from the scanning electromagnet power supply 17 to these coil elements 22A1, 22A2, 22A3, 22B1, 22B2 and 22B3, thereby forming an X-direction magnetic field Bx in the Y-direction scanning electromagnet device 16. This magnetic field Bx , the charged particle beam 1 is deflected in the Y direction and scanned. Although each of the Y-direction scanning coils 22A and 22B is composed of three coil elements, it may be composed of one, two, or four or more coil elements.

Also, a yoke 28 (FIG. 3) may be installed outside the Y-direction scanning electromagnet device 16 . The yoke 28 is made of a magnetic material such as iron, and its inner peripheral surface is formed in such a size that it contacts or approaches the outer periphery of the Y-direction scanning electromagnet device 16, and its outer peripheral surface is formed to have a constant outer diameter. be. By providing this yoke 28, it is possible to apply a strong magnetic field to the charged particle beam 1 and to suppress leakage of the magnetic field to the outside.

By the way, in order to irradiate the charged particle beam 1 from the beam irradiation device 14 shown in FIG. It is desirable to ensure In order to widen the irradiation field 4, the X-direction scanning coils 21A and 21B of the X-direction scanning electromagnet device 15 and the Y-direction scanning coils 22A and 22B of the Y-direction scanning electromagnet device 16 are brought closer to the charged particle beam 1, It is preferable to increase the magnetic field strength acting on beam 1 . On the other hand, if the X-direction scanning coils 21A and 21B and the Y-direction scanning coils 22A and 22B are brought too close to the charged particle beam 1, the charged particle beam 1 will move toward these X-direction scanning coils 21A and 21B and the Y-direction scanning coils 22A and 22B. , the irradiation field 4 is shaved and becomes smaller.

Therefore, as shown in FIGS. 3 to 5, the X-direction scanning coils 21A and 21B and the Y-direction scanning coils 22A and 22B are set to have small diameters on the upstream side before the charged particle beam 1 is scanned. On the downstream side where the beam 1 is scanned and spreads in a direction orthogonal to the incident direction (S direction) of the charged particle beam 1, the aperture is set large along the incident direction (S direction) of the charged particle beam 1. FIG. In this way, the apertures of the X-direction scanning coils 21A and 21B and the Y-direction scanning coils 22A and 22B are kept at a certain distance or more from the charged particle beam 1, thereby avoiding collision with the charged particle beam 1. Meanwhile, it becomes possible to increase the strength of the magnetic field acting on the charged particle beam 1 .

Furthermore, in the first embodiment, in the X-direction scanning electromagnet device 15, the X-direction scanning coils 21A and 21B are arranged in the incident direction (S 4B and 4C) perpendicular to the direction) of the charged particle beam 1, which is the angle between the one end position of the conductor 24 and the Y direction. ) is set larger on the downstream side (FIG. 4(C)) than on the upstream side (FIG. 4(B)). Further, in the Y-direction scanning electromagnet device 16, the Y-direction scanning coils 22A and 22B are arranged to rotate the conductor 24 in cross sections (FIGS. 5B and 5C) perpendicular to the incident direction (S direction) of the charged particle beam 1. The second aperture angle β, which is the angle between the one end position and the X direction, is closer to the downstream side (FIG. 5C) than the upstream side (FIG. 5B) along the incident direction (S direction) of the charged particle beam 1. ) is set large.

Here, the magnetic field (center magnetic field B) generated by the X-direction scanning coils 21A and 21B and the Y-direction scanning coils 22A and 22B is expressed by the following equation.

Each parameter in the above equation will be described with reference to FIGS. 6 and 7. FIG. B is the central magnetic field, the magnetic field at the trajectory position 3 of the charged particle beam 1; μ is the vacuum permeability. J is the current density of the current flowing through the X-direction scanning coils 21A, 21B and the Y-direction scanning coils 22A, 22B. _nt is the number of turns of the conductor 24 in the X-direction scanning coils 21A, 21B and the Y-direction scanning coils 22A, 22B. I is the current value of the current flowing through the X-direction scanning coils 21A, 21B and the Y-direction scanning coils 22A, 22B. Rin is the inner radius of the X-direction scanning coils 21A, 21B and the Y-direction scanning coils 22A, 22B, and Rout is the outer radius of the X-direction scanning coils 21A, 21B and the Y-direction scanning coils 22A, 22B. θ is the coil angle (0<θ≦π/2) of the X-direction scanning coils 21A and 21B and the Y-direction scanning coils 22A and 22B.

A conventional X-direction scanning electromagnet device 100 is shown in FIG. In this X-direction scanning electromagnet device 100, X-direction scanning coils 101A and 101B that deflect and scan the charged particle beam 1 in the X direction orthogonal to the incident direction (S direction) of the charged particle beam 1 are arranged to scan the charged particle beams. They are provided to face the incident direction (S direction) of the charged particle beam 1 and the Y direction orthogonal to the X direction with the orbital position 102 of the beam 1 interposed therebetween. Furthermore, these X-direction scanning coils 101A and 101B are set such that the aperture along the incident direction (S direction) of the charged particle beam 1 is set larger on the downstream side than on the upstream side.

In such X-direction scanning coils 101A and 101B, the inner radius Rin and the outer radius Rout are increased on the downstream side where the diameter is increased, and the conductor 103 forming the X-direction scanning coils 101A and 101B is the magnetic field generation region. It leaves the track position 102 . Therefore, in the X-direction scanning coils 101A and 101B, the central magnetic field B at the track position 102 is lowered.

Also in the X-direction scanning electromagnet device 15 and the Y-direction scanning electromagnet device 16 of the first embodiment, on the downstream side of the incident direction (S direction) of the charged particle beam 1, the inner radius Rin and the outer radius Rout are larger than those on the upstream side. growing. However, in the X-direction scanning electromagnet device 15 and the Y-direction scanning electromagnet device 16, in order to increase the intensity of the central magnetic field B at the orbit position 3 of the charged particle beam 1, as described above, the incident direction of the charged particle beam 1 is The first opening angle α and the second opening angle β are set large on the downstream side (FIGS. 4C, 5C, 6 and 7) in the (S direction). Therefore, the coil angles θ of the X-direction scanning coils 21A and 21B in the X-direction scanning electromagnet device 15 and the coil angles θ of the Y-direction scanning coils 22A and 22B in the Y-direction scanning electromagnet device 16 decrease and approach 0 degrees. , (sin θ)/θ in the above equation increases. This makes it possible to increase the central magnetic field B of the X-direction scanning coils 21A, 21B and the Y-direction scanning coils 22A, 22B.

On the upstream side of the X-direction scanning electromagnet device 15 (FIG. 4B), the gaps between the coil elements 21A1, 21A2 and 21A3 of the X-direction scanning coil 21A and the gaps between the coil elements 21B1, 21B2 and 21B3 of the X-direction scanning coil 21B are narrow, the first aperture angle α is not set large. Similarly, on the upstream side of the Y-direction scanning electromagnet device 16 (FIG. 5B), the gaps between the coil elements 22A1, 22A2 and 22A3 of the Y-direction scanning coil 22A, the coil elements 22B1 and 22B2 of the Y-direction scanning coil 22B, Since both gaps of 22B3 are narrow, the second opening angle β is not set large.

In the conventional X-direction scanning electromagnet device 100 (FIG. 12), the opening angle γ is set to substantially the same value on the upstream side and the downstream side along the incident direction (S direction) of the charged particle beam 1 .

With the configuration as described above, according to the first embodiment, the following effect (1) can be obtained.
(1) As shown in FIGS. 3 to 5, a first aperture angle α of the X-direction scanning coils 21A and 21B that deflect and scan the charged particle beam 1, and a second aperture angle β of the Y-direction scanning coils 22A and 22B is set larger on the downstream side than on the upstream side along the incident direction (S direction) of the charged particle beam 1 . Therefore, the X-direction scanning electromagnet device 15, Y-direction scanning electromagnet device 15 having the X-direction scanning coils 21A, 21B can be obtained without increasing the number of turns of the conductor 24 forming the X-direction scanning coils 21A, 21B and the Y-direction scanning coils 22A, 22B. The magnetic field intensity of the central magnetic field B at each orbital position 3 of the Y-direction scanning electromagnet device 16 having the directional scanning coils 22A and 22B is shifted downstream compared to the upstream side along the incident direction (S direction) of the charged particle beam 1. can be increased by Thereby, the irradiation field 4 of the beam irradiation device 14 having the X-direction scanning electromagnet device 15 and the Y-direction scanning electromagnet device 16 (that is, the scanning electromagnet device 20) can be secured widely.

[B] Second embodiment (Figs. 8 to 10)
FIG. 8 shows a part of the scanning electromagnet device according to the second embodiment, and is a cross-sectional view corresponding to a cross section taken along line MM in FIG. 4(A). 9 is a perspective view showing the litz wire of FIG. 8. FIG. In the second embodiment, parts similar to those in the first embodiment are denoted by the same reference numerals as those in the first embodiment to simplify or omit the description.

The scanning electromagnet device 30 of the second embodiment differs from the first embodiment in that, as shown in FIGS. Conductors 24 constituting coil elements 22A1 to 22A3 and 22B1 to 22B3 of scanning coils 22A and 22B are litz wires 31, and litz wires 31 are immersed in liquid coolant 5 such as water.

In a scanning electromagnet device as a comparative example, a pair of scanning coils is configured by winding a hollow conductor 200 as a conductor shown in FIG. This hollow conductor 200 is generally used in the electromagnet for the beam accelerator 12 (FIG. 1), and is formed in the hollow with a rectangular cross-sectional shape with a side of several millimeters. be provided.

In the above-described scanning electromagnet device of the comparative form using this hollow conductor 200 as a scanning coil, when the current value flowing through the hollow conductor 200 forming the scanning coil is changed in order to scan the charged particle beam 1, a pair of The magnetic field generated between the scan coils changes, which generates eddy currents 202 in hollow conductor 200 . The magnetic field generated by this eddy current 202 disturbs the magnetic field between the pair of scanning coils, possibly degrading the magnetic field accuracy of the scanning electromagnet device.

On the other hand, in the scanning electromagnet device 30 (the X-direction scanning electromagnet device 15 (FIGS. 3 and 4) and the Y-direction scanning electromagnet device 16 (FIGS. 3 and 5)) of the second embodiment, each X-direction scanning Coil elements 21A1 to 21A3 and 21B1 to 21B3 of the coils 21A and 21B, and coil elements 22A1 to 22A3 and 22B1 to 22B3 of the Y-direction scanning coils 22A and 22B are formed by winding the litz wire 31 shown in FIG. The litz wire 31 is a conductor formed by twisting together a plurality of fine wires 32 which are conductors whose outer surfaces are insulated with an insulating material (for example, enamel).

The coil elements 21A1 to 21A3 and 21B1 to 21B3 of the X-direction scanning coils 21A and 21B and the coil elements 22A1 to 22A3 and 22B1 to 22B3 of the Y-direction scanning coils 22A and 22B are composed of litz wires 31, respectively. Therefore, even if the current value flowing through the litz wire 31 changes and the magnetic field By between the X-direction scanning coils 21A and 21B and the magnetic field Bx between the Y-direction scanning coils 22A and 22B change, A looped eddy current 33 smaller than the eddy current 202 is generated in the wire 32 . Since the magnetic field generated by the eddy current 33 of this small loop is small, the magnetic field generated by this eddy current 33 disturbs the magnetic field By between the X direction scanning coils 21A and 21B and the magnetic field Bx between the Y direction scanning coils 22A and 22B. is reduced.

Further, in the arrangement structure of the litz wire 31 shown in FIG. 21A3, 21B1, 21B2, 21B3, and coil elements 22A1, 22A2, 22A3, 22B1, 22B2, 22B3 of the Y-direction scanning coils 22A, 22B of the Y-direction scanning electromagnet device 16 are accommodated in respective grooves 35, respectively. FIG. 8 shows a state in which the coil element 21A3 is accommodated in the groove 35. As shown in FIG.

A lid member 36 made of a non-metallic material is arranged so as to cover the outer surface of the structure 23, so that the liquid coolant 5 flows between the outer surface of the structure 23 and the lid member 36. 37 is formed. As a result, the litz wires 31 constituting the coil elements 21A1 to 21A3, 21B1 to 21B3, 22A1 to 22A3, and 22B1 to 22B3 accommodated in the grooves 35 of the structure 23 are applied to the liquid refrigerant 5 in the refrigerant flow paths 37. It is immersed and cooled.

With the configuration as described above, the second embodiment also has the same effect as the effect (1) of the first embodiment, and also has the following effects (2) and (3).

(2) As shown in FIGS. 3 to 5 and 9, the coil elements 21A1 to 21A3 and 21B1 to 21B3 of the X direction scanning coils 21A and 21B of the X direction scanning electromagnet device 15, and the Y direction of the Y direction scanning electromagnet device 16 The coil elements 22A1 to 22A3 and 22B1 to 22B3 of the scanning coils 22A and 22B are each composed of the litz wire 31. Since the loop of the eddy current 33 generated in the wire 32 of the litz wire 31 is small, the eddy current 33 The resulting magnetic field is suppressed. By suppressing the magnetic field generated by the eddy current 33 in this way, the magnetic field accuracy of the magnetic field By of the X-direction scanning electromagnet device 15 and the magnetic field accuracy of the magnetic field Bx of the Y-direction scanning electromagnet device 16 can be improved. As a result, the irradiation accuracy of the charged particle beam 1 by the beam irradiation device 14 having the X-direction scanning electromagnet device 15 and the Y-direction scanning electromagnet device 16 can be improved.

(3) For example, when the litz wire 31 formed by twisting a plurality of thin wires 32 as conductors is arranged on the outer periphery of a cooling pipe (not shown), the wires 32 are unwound and adjacent to the inner side. When the wire 32 floats up from the wire 32, the wire 32 is not cooled by the liquid coolant flowing through the cooling pipe, so that the temperature of the wire 32 rises and there is a risk of burning.

On the other hand, like the arrangement structure of the litz wire 31 shown in FIG. It will be. As a result, even if the strands 32 forming the litz wire 31 are lifted from the adjacent strands 32 due to unwinding or the like, all the strands 32 can be suitably cooled by the liquid coolant 5, and the litz wire 31 can be cooled. Defects can be avoided.

[C] Third embodiment (Fig. 11)
FIG. 11 is a cross-sectional view showing part of the scanning electromagnet device according to the third embodiment. In the third embodiment, the same parts as those in the first and second embodiments are denoted by the same reference numerals as those in the first and second embodiments, thereby simplifying or omitting the description.

The scanning electromagnet device 40 of the third embodiment differs from the first and second embodiments in that the coil elements 21A1 to 21A3 and 21B1 to 21B3 of the X-direction scanning coils 21A and 21B and the coils of the Y-direction scanning coils 22A and 22B The point is that the litz wires 31 constituting the elements 22A1 to 22A3 and 22B1 to 22B3 are impregnated with a resin 41 and the resin 41 comes into contact with the liquid coolant 5 .

That is, a plurality of grooves 42 are formed on the outer surface of the structure 23, and the coil elements 21A1, 21A2, 21A3, 21B1, 21B2, 21B3, 22A1, 22A2, 22A3 of the X-direction scanning electromagnet device 15 and the Y-direction scanning electromagnet device 16 are formed. , 22 B 1 , 22 B 2 , 22 B 3 are accommodated in respective grooves 42 and impregnated with resin 41 . FIG. 11 shows a state in which the coil element 21A3 is accommodated in the groove 42 and impregnated with the resin 41. As shown in FIG.

A coolant channel 43 through which the liquid coolant 5 flows is formed between the outer surface of the structure 23 and the lid member 36 , and the liquid coolant 5 in the coolant channel 43 contacts the resin 41 . As a result, the litz wires 31 constituting the coil elements 21A1 to 21A3, 21B1 to 21B3, 22A1 to 22A3, and 22B1 to 22B3 accommodated in the grooves 42 of the structure 23 and impregnated with the resin 41 are passed through the resin 41. It is cooled by liquid coolant 5 .

With the above configuration, according to the third embodiment, in addition to the effects (1) to (3) of the first and second embodiments, the following effect (4) can be obtained. Play.

(4) The litz wire 31 is impregnated with the resin 41 and the resin 41 is in contact with the liquid coolant 5 . As a result, all the strands 32 forming the litz wire 31 are suitably cooled by the liquid coolant 5 via the resin 41 . Furthermore, the litz wire 31 is accommodated in the groove 42 of the structure 23 and impregnated with the resin 41, so that even when an electromagnetic force acts on the litz wire 31, the vibration of the litz wire 31 can be suppressed reliably. can be done.

Although several embodiments of the invention have been described above, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention, and these replacements and changes can be made. is included in the scope and gist of the invention, and is included in the scope of the invention described in the claims and its equivalents.

For example, even if the X-direction scanning electromagnet device 15 and the Y-direction scanning electromagnet device 16 are arranged in series along the incident direction (S) of the charged particle beam 1, this embodiment can be applied.

DESCRIPTION OF SYMBOLS 1... Charged particle beam, 2... Irradiation object, 10... Charged particle beam irradiation system, 14... Beam irradiation apparatus, 15... X-direction scanning electromagnet apparatus, 16... Y-direction scanning electromagnet apparatus, 20... Scanning electromagnet apparatus, 21A, 21B X-direction scanning coil 22A, 22B Y-direction scanning coil 23, 25 Structure (coil support) 24 Conductor 30 Scanning electromagnet device 31 Litz wire 32 Element wire 37 Refrigerant Flow path 40 Scanning electromagnet device 41 Resin 43 Coolant flow path α First opening angle β Second opening angle

Claims (8)

a scanning coil that deflects and scans the charged particle beam in a first direction perpendicular to the direction of incidence of the charged particle beam;
a plurality of the scanning coils are arranged to face each other in a second direction orthogonal to the incident direction and the first direction with the orbital position of the charged particle beam interposed therebetween;
These scanning coils have a diameter along the direction of incidence set larger on the downstream side than on the upstream side,
Each of the scanning coils is formed by winding a conductor, and an opening angle, which is an angle formed by one end position of the conductor in a cross section perpendicular to the incident direction and the second direction, is in the incident direction. A scanning electromagnet device characterized in that the downstream side is set larger than the upstream side along the line. a first scanning electromagnet device comprising a first scanning coil that deflects and scans the charged particle beam in a first direction orthogonal to an incident direction of the charged particle beam;
a second scanning electromagnet device comprising a second scanning coil that deflects and scans the charged particle beam in a second direction orthogonal to the incident direction and the first direction;
the second scanning electromagnet device is arranged outside or inside the first scanning electromagnet device and at the same position in the direction of incidence;
A plurality of the first scanning coils are arranged to face each other in the second direction with the orbital position of the charged particle beam interposed therebetween, and the second scanning coils are arranged in the first direction with the orbital position of the charged particle beam interposed therebetween. are placed facing each other,
The first scanning coil and the second scanning coil have a diameter along the direction of incidence set larger on the downstream side than on the upstream side,
Each of the first scanning coils is formed by winding a conductor, and a first aperture angle, which is an angle between one end position of the conductor in a cross section perpendicular to the incident direction and the second direction, is is set larger on the downstream side than on the upstream side along the incident direction,
Each of the second scanning coils is formed by winding the conductor, and has a second aperture angle, which is an angle between one end position of the conductor in a cross section perpendicular to the incident direction and the first direction. 1. A scanning electromagnet device characterized in that it is set to be larger on the downstream side than on the upstream side along the incident direction. 3. A scanner according to claim 1 or 2, wherein said scanning coil, said first scanning coil or said second scanning coil is arranged to be held in place by a coil support made of non-metallic material. electromagnet device. The scanning coil, the first scanning coil, or the second scanning coil is configured by winding a litz wire formed by twisting a plurality of conductor strands whose surfaces are insulated with an insulating material. The scanning electromagnet device according to any one of claims 1 to 3, characterized by: 5. The scanning electromagnet device according to claim 4, wherein the litz wire constituting said scanning coil, said first scanning coil, or said second scanning coil is immersed in a liquid coolant. 5. The scanning device according to claim 4, wherein the litz wire constituting said scanning coil, said first scanning coil, or said second scanning coil is impregnated with a resin, and the resin is in contact with a liquid coolant. electromagnet device. 7. The scanning electromagnet device according to claim 5, further comprising a coolant channel through which said liquid coolant flows, said coolant channel being made of a non-metallic material. A beam irradiation device comprising the scanning electromagnet device according to any one of claims 1 to 7, wherein the beam irradiation device deflects and scans a charged particle beam by the scanning electromagnet device and irradiates an irradiation target. A charged particle beam irradiation system characterized by being configured to:

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