JP6878169B2 - Superconducting coil support structure of superconducting magnet device, and superconducting magnet device - Google Patents

Description

An embodiment of the present invention relates to a superconducting coil support structure of a superconducting magnet device and a superconducting magnet device provided with the superconducting coil support structure.

In the superconducting magnet device, in order to cool the internal superconducting coil to an extremely low temperature to bring it into a superconducting state, it is necessary to suppress the amount of heat transfer from the outside of the superconducting magnet device to the superconducting coil. Therefore, the coil support that connects the iron core as a coil support in which the superconducting coil is arranged inside and the vacuum vessel that is the exterior of the superconducting magnet device, and supports the superconducting coil and the iron core suppresses the amount of heat penetration. Therefore, the number of magnets is reduced as much as possible, the cross-sectional area is reduced, and the material is composed of a material having low thermal conductivity.

Furthermore, since the coil support is made of a material with low thermal conductivity (for example, a composite material), its rigidity is lower than that of a metal material, and when it is attached to an iron core that shrinks due to cooling, it receives tensile stress and becomes a superconducting coil. It is necessary to secure sufficient strength because electromagnetic force acts by excitation. However, since the low heat penetration amount and the high strength have a contradictory relationship, the coil support needs to be optimally designed to satisfy both of these conditions.

Japanese Unexamined Patent Publication No. 2010-287792 Jikkenhei 1-157457

By the way, since the superconducting magnet device for the particle beam medical device is installed in the rotating gantry, the load direction due to gravity changes due to the rotation. If the deformation of the coil support increases with this, the center position of the superconducting coil shifts, the particle beam is deflected, and there arises a problem that the focusing efficiency of the particle beam is further lowered.

For example, in the superconducting coil support structure of the first conventional technique shown in FIG. 7A, when the load direction due to gravity is arrow A, the coil support 103 for supporting the superconducting coil 100 and the iron core 101 on the vacuum vessel 102 Since it is arranged along the load direction (arrow A), the center position of the superconducting coil 100 does not deviate significantly. However, when the superconducting magnet device rotates and the load direction due to gravity becomes arrow B, the coil support 103 is not arranged along the load direction due to gravity (arrow B), so that the coil support 103 is loaded in the shear direction. In response to this, a bending moment will act. This bending moment causes the coil support 103 to bend, and the center position of the superconducting coil 100 shifts.

On the other hand, in the superconducting coil support structure of the second conventional technique shown in FIG. 7B, by arranging the coil supports 104 in a radial pattern, the deviation of the center position of the superconducting coil 100 due to the rotation of the superconducting magnet device can be prevented. It becomes possible to correspond. However, in order to support the load of the superconducting coil 100 and the iron core 101 in the compression direction of the coil support 104, it is necessary to fix the coil support 104 to the vacuum vessel 102 and the iron core 101 so as not to move in the axial direction. Therefore, when the superconducting coil 100 is cooled, tensile stress due to the diameter reduction of the iron core 101 is generated in the coil support 104. In order to cope with this, when the coil support 104 is thickened to increase the strength, the cross-sectional area of the coil support 104 increases, and the amount of heat transfer from the vacuum vessel 102 to the superconducting coil 100 via the coil support 104 increases. Resulting in.

The embodiment of the present invention has been made in consideration of the above circumstances, and can support the superconducting coil so that its center position does not shift even if the superconducting magnet device rotates, and also from the outside to the superconducting coil. It is an object of the present invention to provide a superconducting coil support structure of a superconducting magnet device capable of suppressing a heat penetration amount, and a superconducting magnet device.

The superconducting coil support structure of the superconducting magnet device according to the embodiment of the present invention includes an iron core which is a coil support for arranging and supporting a superconducting coil cooled in a superconducting state by a refrigerating machine, and the superconducting coil and the iron core . It is a superconducting coil support structure of a superconducting magnet device having a vacuum container that is housed in an inner space and holds the inner space in a vacuum state, and an end support member that supports the end of the iron core by the vacuum container. The end support member is formed by connecting a ring-shaped frame and a plurality of radial frames extending in the radial direction of the ring-shaped frame, and the radial frame is connected to the inside and the outside of the ring-shaped frame, respectively. Is positioned unevenly in the circumferential direction of the ring-shaped frame, and the innermost first connecting portion of the radial frame in the end support member is connected to the end portion of the iron core, and the end support member. The outermost second connecting portion of the radial frame is connected to the lid of the vacuum vessel, and at least one of the first connecting portion and the second connecting portion is the end portion of the iron core and the vacuum vessel. It is characterized in that it is configured to be movably connected to the lid in the radial direction of the end support member.

The superconducting magnet device according to the embodiment of the present invention is characterized by including the superconducting coil support structure of the superconducting magnet device according to the embodiment of the present invention.

According to the embodiment of the present invention, the superconducting coil can be supported so that its center position does not shift even if the superconducting magnet device rotates, and the amount of heat invading the superconducting coil from the outside can be suppressed.

The perspective view which shows the particle beam therapy apparatus which comprises the superconducting magnet apparatus to which the superconducting coil support structure of the superconducting coil apparatus which concerns on one Embodiment of this invention is applied. The perspective view which shows the superconducting magnet device of FIG. The perspective view which shows by removing the container body of the vacuum container of FIG. The perspective view which shows by removing the radiation shield of FIG. FIG. 2 is a cross-sectional view taken along the line VV of FIG. FIG. 3 is a cross-sectional view taken along the line VI-VI of FIG. The prior art of the superconducting coil support structure in the superconducting magnet device is shown, (A) is a schematic cross-sectional view of the first prior art, and (B) is a schematic cross-sectional view of the second prior art.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view showing a particle beam therapy apparatus equipped with a superconducting magnet device to which the superconducting coil support structure of the superconducting magnet device according to the embodiment of the present invention is applied, and FIG. 2 is a perspective view showing the superconducting magnet of FIG. It is a perspective view which shows the apparatus. The particle beam therapy device 10 shown in FIG. 1 includes a cylindrical rotating gantry 11, and a bed 12 on which a patient is placed is installed at a rotation center position of the rotating gantry 11. Further, in the rotating gantry 11, a plurality of superconducting magnet devices 13 are arranged and installed along the trajectory of the beam of heavy particles. The velocity and position of the heavy particles are adjusted by the action of the electromagnetic force generated by exciting the superconducting coil 15 (described later) of the superconducting magnet device 13. The particle beam therapy device 10 treats the patient by irradiating heavy particles from an arbitrary position around the patient lying on the bed 12 by rotating the rotating gantry 11 around the center of rotation thereof.

As shown in FIGS. 2 to 5, the superconducting magnet device 13 includes a superconducting coil 15, an iron core 16 as a coil support, a vacuum container 17 as an exterior of the superconducting magnet device 13, a radiation shield 18, a refrigerator 19, and an end. It is configured to have a coil support 20 as a part support member. Reference numeral 21 in FIG. 5 is a beam duct through which heavy particles pass.

As shown in FIG. 5, the superconducting coil 15 is formed by winding a superconducting wire, and is cooled to an extremely low temperature (about 4K) by a refrigerator 19 to be in a superconducting state. The iron core 16 supports the superconducting coil 15 by arranging it inside.

As shown in FIGS. 2 and 5, the vacuum container 17 includes a container body 22 having a substantially cylindrical shape and a lid body 23 that closes the openings at both ends of the container body 22, and is formed in the inner space M. It houses the superconducting coil 15 and the iron core 16. The vacuum vessel 17 is connected to a vacuum pump (not shown), and the operation of the vacuum pump keeps the inner space M in a vacuum state.

As shown in FIGS. 2, 3 and 5, the radiation shield 18 is installed so as to surround the iron core 16 in the inner space M of the vacuum container 17. That is, the radiation shield 18 is arranged between the container body 22 of the vacuum container 17 and the iron core 16, and is supported by the vacuum container 17 by a heat insulating support (not shown). The radiant shield 18 is cooled to an extremely low temperature (about 50 K) by the refrigerator 19 as described later, thereby blocking the radiant heat transferred from the vacuum vessel 17 to the iron core 16 and the superconducting coil 15.

As shown in FIG. 5, the refrigerator 19 is a two-stage type, for example, a GM type (Gifford McMaphone type) refrigerator. The first-stage cold head 19A of the refrigerator 19 is thermally connected to the radiation shield 18, and the radiation shield 18 is cooled to an extremely low temperature (about 50K). The second cold head 19B of the refrigerator 19 is thermally connected to the superconducting coil 15 via the heat transfer member 24, and cools the superconducting coil 15 and the iron core 16 to an extremely low temperature (about 4K).

As shown in FIGS. 4 and 6, the coil support 20 supports the end portion 26 of the iron core 16 with the lid 23 of the vacuum vessel 17. That is, the coil support 20 has a spider web shape in which a plurality of ring-shaped frames 27 provided concentrically and a plurality of radial frames 28 extending in the radial direction of the ring-shaped frame 27 are connected in the same plane. It was formed in.

Of the coil supports 20, the radial frames 28 coupled to the inside and the outside of the ring-shaped frame 27 are not on the same straight line in the radial direction of the coil support 20, but are biased in the circumferential direction of the ring-shaped frame 27. It is positioned alternately (shifted). Specifically, the radial frames 28 inside and outside the ring-shaped frame 27 are located at intermediate positions of the radial frames 28 adjacent to each other in the circumferential direction of the coil support 20 on one of the inside and the outside (for example, inside). The other outer (eg, outer) radial frame 28 is arranged. Further, the radial frame 28 is arranged symmetrically with respect to the axis of the coil support 20 (for example, the axis O).

In the coil support 20 formed as described above, the first connecting portion 31 of the innermost radial frame 28 in the coil support 20 is engaged with and connected to the recess 29 formed in the end portion 26 of the iron core 16. To. Further, the second connecting portion 32 of the outermost radial frame 28 in the coil support 20 is engaged with and connected to the recess 30 formed in the lid 23 of the vacuum vessel 17. At least one of the first connecting portion 31 and the second connecting portion 32, in the present embodiment, the first connecting portion 31 and the second connecting portion 32 have the first connecting portion 31 in the recess 29 of the end portion 26 of the iron core 16. On the other hand, the second connecting portion 32 is movably connected to the recess 30 of the lid 23 of the vacuum vessel 17 in the radial direction of the coil support 20, respectively.

When the superconducting magnet device 13 rotates with the rotation of the rotating gantry 11 shown in FIG. 1, the coil support 20 has the first connecting portion 31 and the second connecting portion 31 and the second connecting portion 31 of the radial frame 28 on the horizontal axis P as shown in FIG. The connecting portion 32 mainly supports the load of the superconducting coil 15 and the iron core 16. Since the radial frame 28 extends in the radial direction of the ring-shaped ring-shaped frame 27 and is coupled to the ring-shaped frame 27, the coil support 20 is reinforced by the ring-shaped frame 27 to form a high-strength coil support 20. Will be done. Therefore, in the coil support 20, the ring-shaped frame 27 prevents an increase in the amount of deflection of the radial frame 28 on the horizontal axis P.

Further, as shown in FIGS. 3 and 6, protrusions 33 extending in the axial direction of the radiation shield 18 are projected from a plurality of positions along the circumferential direction of the radiation shield 18 on both end faces of the radiation shield 18. .. The protrusions 33 are arranged between the plurality of ring-shaped frames 27 in the coil support 20 and between the radial frames 28 adjacent to each other in the circumferential direction of the coil support 20. Further, the coil support 20 is thermally connected between the plurality of ring-shaped frames 27 and to the radial frames 28 adjacent to each other in the circumferential direction of the coil support 20 by using the protrusion 33 of the radiation shield 18 and the wire 34. An anchor 35 is provided. The wire 34 connects the thermal anchor 35 of the coil support 20 and the protrusion 33 of the radiation shield 18 so as to be stretchable and bendable.

Since it is configured as described above, according to the present embodiment, the following effects (1) to (6) are obtained.
(1) As shown in FIG. 6, the coil support 20 for supporting the end portion 26 of the iron core 16 for supporting the superconducting coil 15 on the lid 23 of the vacuum vessel 17 has a ring-shaped frame 27 and a radial frame 28 coupled to each other. It is composed of high strength. Therefore, when the superconducting magnet device 13 rotates with the rotation of the rotating gantry 11 of the particle beam therapy device 10 and stops at an arbitrary position, the coil support 20 does not deform under the load of the superconducting coil 15 and the iron core 16, and therefore, , The superconducting coil 15 can be supported so that its center position does not shift. As a result, the deflection of the heavy particle beam can be prevented, and the decrease in the focusing efficiency of the heavy particle beam can be suppressed.

(2) In the coil support 20, the radial frame 28 coupled to the inside and the outside of the ring-shaped frame 27 is positioned unevenly (shifted) in the circumferential direction of the ring-shaped frame 27. Therefore, the heat conduction path from the vacuum vessel 17 to the iron core 16 and the superconducting coil 15 in the coil support 20 is the amount of deviation of the radial frames 28 inside and outside the ring-shaped frame 27 in the circumferential direction of the ring-shaped frame 27. It becomes longer by the amount, and the thermal resistance of the coil support 20 increases.

Moreover, the first connecting portion 31 of the radial frame 28 in the coil support 20 has a recess 29 of the end portion 26 of the iron core 16, and the second connecting portion 32 has a recess 30 of the lid 23 of the vacuum vessel 17. The coil support 20 is configured to be movable in the radial direction. Therefore, even if the diameter of the iron core 16 is reduced when the superconducting coil 15 is cooled, no tensile stress is generated in the radial frame 28 of the coil support 28. Therefore, in order to increase the strength of the coil support 20, the coil support 20 is particularly radial. It is not necessary to increase the cross-sectional area of the frame 28.

As described above, since the thermal resistance of the coil support 20 has increased and the increase in the cross-sectional area of the coil support 20, particularly the radial frame 28, can be prevented, the amount of heat penetration from the outside of the vacuum vessel 17 into the superconducting coil 15 can be reduced. It can be suppressed, and the superconducting coil 15 can be suitably cooled to an extremely low temperature (about 4K) and maintained in the superconducting state.

(3) Since the coil support 20 has a thermal anchor 35 that is thermally connected to the protrusion 33 of the radiation shield 18 by using a wire 34, the coil support 20 is cooled to an extremely low temperature (about 50K) similar to that of the radiation sheet 18. Will be done. As a result, the heat transferred from the vacuum vessel 17 to the coil support 20 can be reliably prevented from entering the superconducting coil 15 via the iron core 16.

(4) The thermal anchor 35 of the coil support 20 and the protrusion 33 of the radiation shield 18 are connected by a wire 34 that can be expanded and contracted and bent and deformed. Therefore, when the superconducting magnet device 13 rotates with the rotation of the rotating gantry 11 of the particle beam therapy device 10, even if the coil support 20 and the radiation shield 18 are relatively displaced, the coil support 20 and the radiation sheet 18 can be used. , It is possible to prevent the displacement of one from affecting the other.

(5) In the coil support 20, the radial frame 28 is arranged symmetrically with respect to the coil support 20. Therefore, when the superconducting magnet device 13 rotates with the rotation of the rotating gantry 11 of the particle beam therapy device 10 and stops at an arbitrary position, the radial frame 28 of the coil support 18 changes the superconducting coil 15 and the iron core at each stop position. 16 loads can be reliably supported.

(6) In the coil support 20, the radial frames 28 inside and outside the ring-shaped frame 27 are located at intermediate positions of the radial frames 28 adjacent to each other in the circumferential direction of the coil support 20 on either the inside or the outside, and are inside and outside. The other radial frame 28 is arranged. Therefore, since the heat conduction path from the vacuum vessel 17 to the iron core 16 and the superconducting coil 15 in the coil support 20 can be set to be the longest, the amount of heat penetration from the vacuum vessel 17 to the superconducting coil 15 can be effectively suppressed.

Although the embodiment of the present invention has been described above, this embodiment is presented as an example and is not intended to limit the scope of the invention. This embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention, and the replacements and changes thereof can be made. , It is included in the scope and gist of the invention, and is also included in the scope of the invention described in the claims and the equivalent scope thereof.

For example, in the coil support 20, the number of radial frames 28 does not necessarily have to be the same inside and outside the ring-shaped frame 27. Further, one or three or more ring-shaped frames 27 may be provided. Further, the coil support does not have to be a magnetic iron core 16, and may be made of, for example, a non-magnetic material made of stainless steel.

13 ... Superconducting magnet device, 15 ... Superconducting coil, 16 ... Iron core (coil support), 17 ... Vacuum container, 18 ... Radiation shield, 19 ... Refrigerator, 20 ... Coil support (end support member), 27 ... Ring shape Frame, 28 ... radial frame, 31 ... first connecting part, 32 ... second connecting part, 34 ... wire, 35 ... thermal anchor, M ... inner space, O ... axis.

Claims (6)

An iron core , which is a coil support for arranging and supporting a superconducting coil cooled by a refrigerator into a superconducting state, and the superconducting coil and the iron core are housed in an inner space, and the inner space is kept in a vacuum state. A superconducting coil support structure of a superconducting magnet device having a vacuum container and an end support member for supporting the end of the iron core by the vacuum container.
The end support member is formed by connecting a ring-shaped frame and a plurality of radial frames extending in the radial direction of the ring-shaped frame.
The radial frame coupled to the inside and the outside of the ring-shaped frame is positioned unevenly in the circumferential direction of the ring-shaped frame.
The innermost first connecting portion of the radial frame in the end support member is connected to the end of the iron core , and the outermost second connecting portion of the radial frame in the end support member is the vacuum vessel . Connected to the lid , at least one of the first connecting portion and the second connecting portion can move in the radial direction of the end support member with respect to the end of the iron core and the lid of the vacuum vessel. The superconducting coil support structure of the superconducting magnet device, which is characterized by being connected to and configured in. A radiation shield that surrounds the iron core and is cooled by a refrigerator is arranged in the inner space of the vacuum vessel, and the end support member has a thermal anchor that is thermally connected to the radiation shield. The superconducting coil support structure of the superconducting magnet device according to claim 1. The superconducting coil support structure of the superconducting magnet device according to claim 2, wherein the thermal anchor of the end support member is connected to the radiation shield so as to be stretchable and bendable. The superconducting coil support structure of the superconducting magnet device according to any one of claims 1 to 3, wherein the radial frame of the end support member is arranged symmetrically with respect to the end support member. The radial frames on the inside and outside of the ring-shaped frame in the end support member indicate that the radial frame on the inner and outer sides is arranged at an intermediate position between the adjacent radial frames on one of the inner and outer sides. The superconducting coil support structure of the superconducting magnet device according to any one of claims 1 to 4. A superconducting magnet device comprising the superconducting coil support structure of the superconducting magnet device according to any one of claims 1 to 5.

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