JP6171789B2 - Superconducting equipment - Google Patents

Description

  The present invention relates to a superconducting device, and more particularly to a superconducting device that cools a superconducting coil using a refrigerator.

  A superconducting coil wound with a superconducting wire is used at an extremely low temperature. For example, Japanese Patent Laid-Open No. 6-188466 (Patent Document 1) discloses a superconducting device that cools a superconducting coil using a refrigerator. This type of superconducting device is also called a refrigerator-cooled superconducting device.

  In the refrigerator-cooled superconducting device described in Patent Document 1, a regenerator that cools by adiabatic expansion of a refrigerant having a regenerator material inside the superconducting coil provided in the container of the vacuum heat insulating layer, and its A refrigerator having a piston driving motor is directly attached.

  Although the configuration in which the superconducting coil is directly cooled by the refrigerator as described above can improve the cooling efficiency, since the distance between the refrigerator and the superconducting coil is short, a large leakage magnetic field is applied to the refrigerator and the motor stops. There is a problem. Therefore, in patent document 1, the magnetic body shield is provided so that the motor of a refrigerator may be enclosed with a ferromagnetic board.

JP-A-6-188466 Japanese Patent No. 4796393 Japanese Patent No. 4157424

  In the technique described in Patent Literature 1 described above, the leakage magnetic field is prevented from entering the motor by completely surrounding the motor with a ferromagnetic plate. However, since a pipe for supplying refrigerant from the compressor, a power cable, and the like are connected to the motor, if the periphery of the motor is completely covered with a ferromagnetic plate, maintenance of the refrigerator becomes difficult. Therefore, it is desirable to provide an opening in the magnetic shield.

  However, in order to provide an opening in the magnetic shield, it is necessary to increase the thickness of the ferromagnetic plate or increase the thickness so as to reliably prevent the leakage magnetic field from entering from the opening. As a result, the volume and weight of the magnetic shield increase, leading to an increase in the volume and weight of the superconducting device. Further, since the magnetic attraction force between the magnetic shield and the superconducting coil increases due to the increase in the size of the magnetic shield, there arises a problem that a large electromagnetic force is applied to the superconducting coil.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a refrigerator motor with a configuration suitable for downsizing and weight reduction in a refrigerator-cooled superconducting device. It is to protect against the leakage magnetic field of the superconducting coil body.

  A superconducting device according to the present invention includes a superconducting coil body, a container that houses the superconducting coil body, a refrigerator that is fixed to the container and that drives the built-in motor to cool the superconducting coil body, and is disposed around the motor. And a magnetic shield. The magnetic shield includes first and second wall portions each extending in the coil radial direction of the superconducting coil body and arranged to face each other with the motor interposed therebetween. The first wall portion is disposed at a position where the strength of the magnetic field generated by the superconducting coil body is relatively higher than that of the second wall portion. The length of the first wall portion in the coil radial direction is longer than the length of the second wall portion in the coil radial direction.

  According to the present invention, in the refrigerator-cooled superconducting device, the motor of the refrigerator can be protected from the leakage magnetic field of the superconducting coil body by a configuration suitable for miniaturization and weight reduction.

1 is a schematic plan view of a superconducting device according to Embodiment 1 of the present invention. It is a cross-sectional schematic diagram in line segment II-II of FIG. It is a figure which shows typically the positional relationship of the superconducting coil body in the superconducting apparatus by Embodiment 1, a motor, and a magnetic body shield. 4 is a perspective view of a magnetic shield in the superconducting device according to Embodiment 1. FIG. It is a cross-sectional schematic diagram of the superconducting device according to Embodiment 2 of the present invention. It is a figure which shows typically the positional relationship of the superconducting coil body in the superconducting apparatus by Embodiment 2, a motor, and a magnetic body shield. 6 is a perspective view of a magnetic shield in a superconducting device according to Embodiment 2. FIG. FIG. 5 is a schematic plan view of a superconducting device according to a modification of the first embodiment. FIG. 6 is a perspective view of a magnetic shield in a superconducting device according to a modification of the first embodiment.

[Description of Embodiment of Present Invention]
First, the contents of the embodiment of the present invention will be listed and described.

  (1) A superconducting device according to an embodiment includes a superconducting coil body, a container that houses the superconducting coil body, a refrigerator that is fixed to the container and that drives a built-in motor to cool the superconducting coil body, And a magnetic shield disposed around. The magnetic shield includes first and second wall portions each extending in the coil radial direction of the superconducting coil body and arranged to face each other with the motor interposed therebetween. The first wall portion is disposed at a position where the strength of the magnetic field generated by the superconducting coil body is relatively higher than that of the second wall portion. The length of the first wall portion in the coil radial direction is longer than the length of the second wall portion in the coil radial direction.

  In this way, since the strength of the leakage magnetic field at the position where the first wall portion is disposed is stronger than the strength of the leakage magnetic field at the position where the second wall portion is disposed, the first wall portion is More magnetic flux is allowed to pass than the second wall portion. In the present embodiment, by increasing the length of the first wall portion in the coil radial direction, it is possible to prevent the magnetic flux that has passed through the first wall portion from entering the motor. And since the 1st wall part mainly prevents the penetration | invasion of the leakage magnetic field to a motor, the length in the coil radial direction of a 2nd wall part can be shortened. As a result, the piping and the power cable can be easily routed in the opening surrounded by the first wall and the second wall. In addition, since it is not necessary to increase the thickness of the ferromagnetic plate constituting the magnetic shield, the superconducting device is not reduced in size and weight, and the superconducting coil body is prevented from being subjected to a large electromagnetic force. Can do.

  (2) In the superconducting device, the distance between the end portion of the first wall portion on the inner peripheral side in the coil radial direction and the center portion of the superconducting coil body is the end portion on the inner peripheral side of the second wall portion in the coil radial direction. Shorter than the distance between the center of the superconducting coil body.

  The intensity of the leakage magnetic field of the superconducting coil body decreases as the distance from the central portion of the superconducting coil body (corresponding to the central portion in the direction along the central axis of the superconducting coil body) increases along the coil radial direction. Since the strength of the leakage magnetic field at the position where the first wall portion is disposed is stronger than the strength of the leakage magnetic field at the position where the second wall portion is disposed, the first wall portion is the second wall portion. Compared to more magnetic flux. By increasing the length of the first wall portion in the coil radial direction, the leakage magnetic field of the superconducting coil body is prevented from entering the motor.

  (3) In the superconducting device, the first wall portion and the second wall portion are arranged to face each other across the motor in the circumferential direction of the superconducting coil body.

  If it does in this way, a space margin will arise in the circumferential direction of a superconducting coil body in the opening part surrounded by the 1st wall part and the 2nd wall part. Thereby, routing of piping, a power cable, etc. becomes easy.

  (4) In the superconducting device, the first wall portion and the second wall portion are arranged to face each other across the motor in the coil axis direction of the superconducting coil body.

  If it does in this way, a spatial margin will arise in the coil axial direction of a superconducting coil body in the opening part surrounded by the 1st wall part and the 2nd wall part. Thereby, routing of piping, a power cable, etc. becomes easy.

  (5) In the superconducting device, the position of the end of the second wall portion on the outer peripheral side in the coil radial direction and the position of the end portion on the outer peripheral side of the motor in the coil radial direction are the same in the coil radial direction of the superconducting coil body. Position.

  In this way, since the leakage magnetic field of the superconducting coil body can be prevented from entering the motor from the outside of the second wall portion, the motor can be protected from the leakage magnetic field of the superconducting coil body.

  (6) In the superconducting device, the magnetic shield has an opening surrounded by at least the first wall portion and the second wall portion. A refrigerant supply pipe is connected to the refrigerator through the opening.

  In this way, the magnetic shield has a small and lightweight configuration, and realizes protection of the motor from the leakage magnetic field of the superconducting coil body and facilitation of routing of the pipe connected to the refrigerator.

[Details of the embodiment of the present invention]
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

(Embodiment 1)
A superconducting device 1 according to Embodiment 1 of the present invention will be described with reference to FIGS. 1 and 2. The superconducting device 1 includes a cryostat 5, a heat shield 6 held inside the cryostat 5, a superconducting coil body 10 held inside the heat shield 6, and a refrigerator for cooling the superconducting coil body 10. 2 and a magnetic shield 40.

  Superconducting coil body 10 includes a plurality of superconducting coils 12 formed by winding a superconducting wire, an upper support portion 14, and a lower support portion 11. A plurality of superconducting coils 12 are laminated. The upper and lower end surfaces of the laminated superconducting coils 12 are arranged so that the upper support portion 14 and the lower support portion 11 sandwich the upper end surface and the lower end surface.

  A cooling plate 13 for cooling the superconducting coil 12 is disposed between the adjacent superconducting coils 12 stacked and on the upper end surface and the lower end surface of the stacked superconducting coils 12. In FIG. 2, only the cooling plate 13 disposed on the upper end surface and the lower end surface of the superconducting coils 12 stacked is shown, but the cooling plate 13 is also interposed between the adjacent superconducting coils 12 stacked. (Not shown) is arranged. One end of the cooling plate 13 is connected to the second cooling head 31 of the refrigerator 2. Similarly, one end of a cooling plate (not shown) disposed between adjacent superconducting coils 12 is connected to the second cooling head 31. The first cooling head 32 of the refrigerator 2 may be connected to the wall portion of the heat shield 6. In this way, the wall portion of the heat shield 6 can also be cooled by the refrigerator 2.

  The lower support portion 11 of the superconducting coil body 10 is larger in size than the planar shape of the superconducting coil 12, and may have, for example, a circular planar shape. The lower support portion 11 is fixed to the heat shield 6 by a support member 15. The support member has 15 teeth and is a rod-like member, and connects the upper wall of the heat shield 6 and the outer peripheral portion of the lower support portion 11. A plurality of support members 15 are arranged on the outer periphery of the superconducting coil body 10. The support member 15 is disposed so as to surround the superconducting coil 12 at the same interval.

  The heat shield 6 that holds the superconducting coil body 10 is connected to the cryostat 5 by a connecting portion 20. The connecting portions 20 are arranged at equal intervals along the outer peripheral portion of the superconducting coil body 10 so as to surround the central axis of the superconducting coil body 10. The connection part 20 connects the lid body 35 of the cryostat 5 and the upper wall of the heat shield 6.

  The refrigerator 2 is arranged so as to extend from the upper part of the lid 35 of the cryostat 5 to the inside of the heat shield 6. Specifically, the main body 33 and the motor 34 of the refrigerator 2 are disposed above the upper surface of the lid 35. The refrigerator 2 is arranged so as to reach the inside of the heat shield 6 from the main body portion 33.

  The refrigerator 2 is, for example, a Gifford McMahon refrigerator, and is connected through a pipe 37 to a compressor (not shown) that compresses the refrigerant. The refrigerant (for example, helium gas) compressed to a high pressure by the compressor is supplied to the refrigerator 2. The refrigerant is expanded by the displacer driven by the motor 34, whereby the cool storage material provided in the refrigerator 2 is cooled. The refrigerant, which has become low pressure due to expansion, is returned to the compressor and is increased in pressure again.

  The first cooling head 32 of the refrigerator 2 cools the heat shield 6, thereby preventing external heat from entering the heat shield 6. Then, the second cooling head 31 of the refrigerator 2 cools the superconducting coil 12 via the cooling plate 13. Thereby, the superconducting coil body 10 realizes a superconducting state.

  The cryostat 5 including the cryostat main body 36 and the lid 35 has a circular planar shape as shown in FIG. Further, the planar shape of the heat shield 6 is also circular as shown in FIG. In addition, two refrigerators 2 are arranged in the superconducting device 1. The main body 33 and the motor 34 of the two refrigerators 2 are surrounded by a magnetic shield 40. The detailed configuration of the magnetic shield 40 will be described later.

  In the superconducting device 1, an opening 7 that penetrates the cryostat 5 and the heat shield 6 and reaches the bottom wall of the cryostat main body 36 from the lid 35 of the cryostat 5 is formed. The opening 7 is disposed so as to penetrate the central portion of the superconducting coil 12 of the superconducting coil body 10. In the superconducting device 1, a sample to which a magnetic field generated by passing a current through the superconducting coil body 10 is applied can be disposed inside the opening 7.

  The magnetic field generated by the superconducting coil body 10 does not stay in the opening 7 but leaks to the outside of the opening 7 (hereinafter, this magnetic field is also referred to as “leakage magnetic field”). When this leakage magnetic field enters the motor 34 of the refrigerator 2, there arises a problem that the operation of the motor 34 is disturbed.

  In order to prevent the leakage magnetic field from entering the motor 34, a magnetic shield 40 is provided so as to surround the motor 34. In the first embodiment, the magnetic shield 40 is disposed so as to surround the motor 34 and the main body 33, but the magnetic shield 40 may be disposed so as to surround at least the motor 34. . The material of the magnetic plate constituting the magnetic shield 40 is preferably a ferromagnetic material, such as iron, cobalt, nickel and their alloys, or ferrite.

  Here, in order to prevent the leakage magnetic field from entering the motor 34, it is preferable to completely surround the motor 34. On the other hand, since the motor 34 is connected to a refrigerant supply pipe 37, a power cable, and the like from the compressor, if the periphery of the motor 34 is completely covered with the magnetic shield 40, the maintenance of the refrigerator 2 is difficult. turn into.

  Therefore, in the first embodiment, an opening for connecting the pipe 37 and the like to the main body 33 and the motor 34 is formed in the magnetic shield 40. In order to prevent the leakage magnetic field from entering the motor 34 from this opening, it is necessary to sufficiently separate the distance between the opening and the motor 34. However, if the length in the extending direction of the magnetic body surrounding the opening is increased, there arises a problem that the piping 37, the power cable, and the like are complicated.

  Instead, it is conceivable to increase the thickness of the magnetic plate surrounding the opening in order to collect the leakage magnetic field on the magnetic plate. However, the volume and weight of the magnetic shield 40 are increased, and the volume and weight of the superconducting device 1 are increased. Leading to an increase in In addition, since the magnetic attraction force between the magnetic shield 40 and the superconducting coil body 10 is increased due to the increase in size of the magnetic shield 40, a large electromagnetic force is applied to the superconducting coil body 10. Therefore, it is necessary to configure a magnetic shield that can prevent the leakage magnetic field from entering the motor without obstructing the routing of the pipe 37 and the like, and to be small and light.

  Hereinafter, the configuration of the magnetic shield 40 in the superconducting device 1 according to the first embodiment will be described with reference to FIGS. 3 and 4.

  FIG. 3 is a top view of the superconducting device 1 according to the first embodiment, and is a diagram schematically showing a positional relationship among the superconducting coil body 10, the motor 34, and the magnetic shield 40. FIG. FIG. 4 is a perspective view of the magnetic shield 40 in the superconducting device 1 according to the first embodiment.

  As shown in FIGS. 1 and 2, the superconducting coil body 10 is held inside the heat shield 6 held inside the cryostat 5. The main body 33 and the motor 34 of the two refrigerators 2 are disposed above the upper surface of the lid 35 of the cryostat 5.

  With reference to FIG. 3, the magnetic shield 40 includes a first wall portion 40 a extending in the radial direction Ar of the superconducting coil body 10, and a second wall portion 40 b extending in the radial direction Ar of the superconducting coil body 10. And a third wall 40c that connects the first wall 40a and the second wall 40b.

  The first wall portion 40 a and the second wall portion 40 b are arranged so as to face each other with the main body portion 33 and the motor 34 interposed therebetween in the circumferential direction of the superconducting coil body 10. In FIG. 3, the first wall portion 40 a and the second wall portion 40 b are arranged in parallel to each other with a space therebetween. However, if the first wall portion 40 a and the second wall portion 40 b are arranged to face each other with the motor 34 interposed therebetween, The wall 40a and the second wall 40b may not be parallel.

  When a current is passed through the superconducting coil body 10, a magnetic field is generated inside the opening 7 that penetrates the central portion of the superconducting coil body 10. A part of the generated magnetic field leaks from the end of the opening 7 in the axial direction Aa, so that a magnetic flux (leakage magnetic field) is formed radially outward from the central portion of the superconducting coil body 10. The strength of this leakage magnetic field increases as the distance from the central portion of the superconducting coil body 10 (corresponding to the point O in the figure) becomes shorter. The central portion O of the superconducting coil body 10 corresponds to a central portion in the direction along the central axis of the superconducting coil body 10. The left magnetic shield 40 in FIG. 3 is symmetrical with respect to the right magnetic shield 40 in FIG. 3 and a plane perpendicular to the horizontal plane passing through the central portion O of the superconducting coil body 10 and the third wall portion 40c. It is arranged to be. However, the arrangement of the magnetic shield 40 is not limited to the arrangement shown in FIG.

  Here, the distance between the end portion on the radially inner peripheral side of the first wall portion 40a and the central portion O of the superconducting coil body 10 is R1, and the end portion on the radially inner peripheral side of the second wall portion 40b and the superconducting coil. When the distance from the center portion O of the body 10 is R2, a relationship of R1 <R2 is established between the distances R1 and R2. That is, the first wall 40a is disposed at a position where the strength of the leakage magnetic field is relatively higher than that of the second wall 40b.

  In the first embodiment, as shown in FIG. 3, the length of the first wall portion 40a in the radial direction Ar (corresponding to L1 in the drawing) is set to the length of the second wall portion 40b in the radial direction Ar ( (Corresponding to L2 in the figure) (L1> L2).

  With this configuration, the strength of the leakage magnetic field at the position where the first wall portion 40a is disposed is stronger than the strength of the leakage magnetic field at the position where the second wall portion 40b is disposed. 40a passes more magnetic flux compared with the 2nd wall part 40b. And the magnetic flux which passed the 1st wall part 40a leaks from the edge part of the 1st wall part 40a. Therefore, by extending the first wall 40a in the radial direction Ar, the distance between the end of the first wall 40a on the outer peripheral side in the radial direction and the motor 34 is increased, so that the magnetic flux that has passed through the first wall 40a. Can be prevented from entering the motor 34. The length of the first wall portion 40a in the radial direction Ar can be set according to the strength of the leakage magnetic flux.

  As described above, the first wall 40a prevents the leakage magnetic field from entering the motor 34, so that the length L2 of the second wall 40b in the radial direction Ar can be shortened as shown in FIG. The length L2 of the second wall portion 40b in the radial direction Ar may be a length necessary to prevent the leakage magnetic field from entering from the outside of the second wall portion 40b. For example, as shown in FIG. 3, by setting the position of the end portion of the second wall portion 40b on the radially outer peripheral side and the position of the end portion of the motor 34 to the same position in the radial direction Ar, the leakage magnetic field can be prevented from entering. Can be prevented. The same position in the radial direction Ar means that the position of the end portion of the second wall portion 40b on the outer periphery in the radial direction does not necessarily match the position of the end portion of the motor 34. It may protrude somewhat radially outward from the position, or may be somewhat inward. In this case, the allowable range of the difference between the positions of these end portions can be set according to the strength of the leakage magnetic flux.

  Referring to FIG. 4, the magnetic shield 40 further includes a fourth wall portion 40 d that is disposed above the main body portion 33 and the motor 34 and connects the first wall portion 40 a and the second wall portion 40 b. In the magnetic shield 40, an opening surrounded by the first wall 40a, the second wall 40b, and the fourth wall 40d is formed. The pipe 37 and the power cable are connected to the main body 33 and the motor 34 through the opening.

  As described above, in the magnetic shield 40, the length of the second wall portion 40b in the radial direction Ar is mainly the first wall portion 40a to prevent the leakage magnetic field from entering the motor 34. It is shorter than the length in radial direction Ar of 1 wall part 40a. For this reason, the piping 37 and the power cable are easily routed. Further, since it is not necessary to increase the thickness of the magnetic plate constituting the magnetic shield 40, the superconducting device is not hindered in size and weight. Furthermore, it can suppress that a big electromagnetic force is applied to the superconducting coil body 10.

(Embodiment 2)
With reference to FIG. 5, a superconducting device 1A according to Embodiment 2 of the present invention will be described. A superconducting device 1A includes a cryostat 5, a heat shield 6 held inside the cryostat 5, a superconducting coil body 10 held inside the heat shield 6, and a refrigerator for cooling the superconducting coil body 10. 2 and a magnetic shield 42.

  A superconducting device 1A according to the second embodiment is a superconducting device 1 shown in FIGS. 1 and 2 in which a magnetic shield 42 is provided instead of the magnetic shield 40. Since the configuration of superconducting device 1A is the same as that of FIGS. 1 and 2 except for the configuration of magnetic shield 42, detailed description will not be repeated.

  In the second embodiment, the magnetic shield 42 is disposed so as to surround the motor 34 and the main body 33, but the magnetic shield 42 only needs to be disposed so as to surround at least the motor 34. . The material of the magnetic plate constituting the magnetic shield 42 is preferably a ferromagnetic material, such as iron, cobalt, nickel and their alloys, or ferrite.

  Hereinafter, the configuration of the magnetic shield 42 in the superconducting device 1A according to the second embodiment will be described with reference to FIGS.

  FIG. 6 is a cross-sectional view of the superconducting device 1A according to the second embodiment, and is a diagram schematically showing the positional relationship among the superconducting coil body 10, the motor 34, and the magnetic shield 42. FIG. 7 is a perspective view of the magnetic shield 42 in the superconducting device 1A according to the second embodiment.

  As shown in FIG. 5, the superconducting coil body 10 is held inside the heat shield 6 held inside the cryostat 5. The main body 33 and the motor 34 of the refrigerator 2 are disposed above the upper surface of the lid 35 of the cryostat 5.

  Referring to FIG. 6, the magnetic shield 42 includes a first wall portion 42 a extending in the radial direction Ar of the superconducting coil body 10, and a second wall portion 42 b extending in the radial direction Ar of the superconducting coil body 10. And a third wall portion 42c connecting the first wall portion 42a and the second wall portion 42b.

  The first wall portion 42a and the second wall portion 42b are disposed so as to face each other across the main body portion 33 and the motor 34 in the axial direction Aa of the superconducting coil body 10. A hole is formed in the first wall portion 42 a at a portion connecting the main body portion 33 and the second cooling head 32. In FIG. 6, the first wall portion 42 a and the second wall portion 42 b are arranged parallel to each other with a space therebetween. However, if the first wall portion 42 a and the second wall portion 42 b are arranged to face each other with the motor 34 interposed therebetween, The wall part 42a and the second wall part 42b may not be parallel.

  When a current is passed through the superconducting coil body 10, a magnetic field is generated inside the opening 7 that penetrates the central portion of the superconducting coil body 10. A part of the generated magnetic field leaks from the end of the opening 7 in the axial direction Aa, so that a magnetic flux (leakage magnetic field) is formed radially outward from the central portion of the superconducting coil body 10. The strength of this leakage magnetic field increases as the distance from the central portion of the superconducting coil body 10 (corresponding to the point O in the figure) becomes shorter.

  Here, the distance between the end portion on the radially inner peripheral side of the first wall portion 42a and the central portion O of the superconducting coil body 10 is R3, and the end portion on the radially inner peripheral side of the second wall portion 42b and the superconducting coil. When the distance from the center portion O of the body 10 is R4, a relationship of R3 <R4 is established between the distances R3 and R4. In other words, the first wall portion 42a is disposed at a position where the strength of the leakage magnetic field is relatively higher than that of the second wall portion 42b.

  In the second embodiment, as shown in FIG. 6, the length of the first wall portion 42a in the radial direction Ar (corresponding to L3 in the drawing) is set to the length of the second wall portion 42b in the radial direction Ar ( (Equivalent to L4 in the figure)) (L3> L4).

  With this configuration, the strength of the leakage magnetic field at the position where the first wall portion 42a is disposed is stronger than the strength of the leakage magnetic field at the position where the second wall portion 42b is disposed. 42a allows more magnetic flux to pass than the second wall portion 42b. And the magnetic flux which passed the 1st wall part 42a leaks from the edge part of the 1st wall part 42a. Therefore, by extending the second wall portion 42a in the radial direction Ar, the distance between the end of the first wall portion 42a on the outer peripheral side in the radial direction and the motor 34 is increased, thereby passing the first wall portion 42a. Magnetic flux can be prevented from entering the motor 34. The length of the first wall portion 42a in the radial direction Ar can be set according to the strength of the leakage magnetic flux.

  As described above, the first wall portion 42a prevents the leakage magnetic field from entering the motor 34, whereby the length L4 of the second wall portion 42b in the radial direction Ar can be shortened as shown in FIG. The length L4 in the radial direction Ar of the second wall portion 42b only needs to be a length necessary to prevent the leakage magnetic field from entering from the outside of the second wall portion 42b. For example, as shown in FIG. 6, the leakage magnetic field can be prevented from entering by setting the position of the end portion of the second wall portion 42b on the outer peripheral side in the radial direction and the position of the end portion of the motor 34 in the radial direction Ar. Can be prevented. The same position in the radial direction Ar means that the position of the end portion of the second wall portion 42b on the outer periphery in the radial direction does not necessarily match the position of the end portion of the motor 34. It may protrude somewhat radially outward from the position, or may be somewhat inward. In this case, the allowable range of the difference between the positions of these end portions can be set according to the strength of the leakage magnetic flux.

  Referring to FIG. 7, the magnetic shield 42 further includes a fourth wall portion 42d that is disposed on the side portion of the main body portion 33 and the motor 34 and connects the first wall portion 42a and the second wall portion 42b. The magnetic shield 42 has an opening surrounded by the first wall 42a, the second wall 42b, and the fourth wall 42d. The pipe 37 and the power cable are connected to the main body 33 and the motor 34 through the opening.

  As described above, in the magnetic shield 42, the length of the second wall portion 42b in the radial direction Ar is mainly the first wall portion 42a to prevent the leakage magnetic field from entering the motor 34. It is shorter than the length in radial direction Ar of 1 wall part 42a. For this reason, the piping 37 and the power cable are easily routed. Further, as in the first embodiment, since it is not necessary to increase the thickness of the magnetic plate constituting the magnetic shield 42, the superconducting device is not hindered in size and weight reduction. Furthermore, it can suppress that a big electromagnetic force is applied to the superconducting coil body 10.

  In the first and second embodiments described above, the configuration of the magnetic shields 40 and 42 covering the motors 34 of the two refrigerators 2 has been exemplified. However, the number of the refrigerators 2, the individual refrigerators 2 and the superconducting coil bodies are exemplified. The positional relationship with 10 is not limited to this configuration. For example, the number of the motors 34 of the refrigerator 2 may be one or three or more. In any configuration, the magnetic shield has a relative length in the coil radial direction of the wall portion arranged at a position where the strength of the leakage magnetic field from the superconducting coil body is relatively strong. What is necessary is just to make it longer than the length in the coil radial direction of the wall part arrange | positioned in the position which becomes weak automatically.

  Moreover, in Embodiment 1 and 2 mentioned above, although illustrated about the structure which installs the magnetic body shield 40 (or 42) corresponding to the motor 34 of the refrigerator 2 corresponding to 1: 1, FIG. 8 and FIG. As shown in FIG. 4, a plurality of magnetic shields 40 (or 42) may be integrally formed.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The description of the present invention is shown not by the above description but by the scope of the claims, and is intended to include all modifications within the scope and meaning equivalent to the scope of the claims.

  The present invention is advantageously applied to a superconducting device that cools a superconducting coil using a refrigerator.

1, 1A Superconducting equipment 2 Refrigerator 5 Cryostat 6 Heat shield 7 Opening portion 10 Superconducting coil body 11 Lower support portion 12 Superconducting coil 13 Cooling plate 14 Upper support portion 15 Support member 20 Connection portion 31 Second cooling head 32 First cooling head 33 Main body 34 Motor 35 Lid 36 Cryostat main body 37 Piping 40, 42 Magnetic shield 40a, 42a First wall 40b, 42b Second wall 40c, 42c Third wall 40d, 42d Fourth wall

Claims (5)

A superconducting coil body;
A container for housing the superconducting coil body;
A refrigerator that is fixed to the container and drives the built-in motor to cool the superconducting coil body;
A magnetic shield disposed around the motor,
The magnetic shield includes first and second wall portions each extending in the coil radial direction of the superconducting coil body and arranged to face each other across the motor,
The first wall portion is disposed at a position where the strength of the magnetic field generated by the superconducting coil body is relatively stronger than the second wall portion,
The length in the coil diameter direction of the first wall portion, rather long than the length in the coil radial direction of the second wall portion,
The distance between the end portion of the first wall portion on the inner peripheral side in the coil radial direction and the central portion of the superconducting coil body is the same as the distance between the end portion of the second wall portion on the inner peripheral side in the coil radial direction Superconducting equipment that is shorter than the distance to the center . 2. The superconducting device according to claim 1, wherein the first wall portion and the second wall portion are disposed to face each other across the motor in a circumferential direction of the superconducting coil body. 2. The superconducting device according to claim 1, wherein the first wall portion and the second wall portion are disposed to face each other across the motor in a coil axis direction of the superconducting coil body. The position of the end portion of the second wall portion on the outer peripheral side in the coil radial direction and the position of the end portion on the outer peripheral side of the coil radial direction of the motor are the same position in the coil radial direction of the superconducting coil body. The superconducting device according to any one of claims 1 to 3 . The magnetic shield includes an opening surrounded by at least the first wall and the second wall, and a refrigerant supply pipe is connected to the refrigerator through the opening. The superconducting device according to any one of claims 1 to 4 .

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