JP5708255B2 - Superconducting coil and superconducting magnet - Google Patents

Description

  The present invention relates to a superconducting coil and a superconducting magnet.

  According to Japanese Patent Laid-Open No. 11-186025, stacked first and second pancake coils and a cooling plate provided so as to be interposed between the first pancake coils and the second pancake coils A superconducting coil is disclosed. The cooling plate is connected to the cooling head via a heat conducting bar.

JP-A-11-186025

  In order to efficiently cool the coil portion by the cooling head, it is necessary to reduce the thermal resistance between the cooling head and the cooling plate. However, sufficient studies have not been made so far, and the cooling efficiency of the coil portion has not been sufficiently high.

  Therefore, an object of the present invention is to provide a superconducting coil and a superconducting magnet that can increase the cooling efficiency of the coil portion.

  The superconducting coil of the present invention has a coil part, a cooling head, and a heat transfer part. The coil portion is formed by winding a superconducting wire. The cooling head has a coolable end. The end of the cooling head has an end surface and a side surface surrounding the end surface. The heat transfer part connects the coil part and the cooling head to each other. The heat transfer section has a first heat transfer plate and a fixture. The first heat transfer plate is attached to the coil portion at the first position. The fixture holds the first heat transfer plate and is attached to the cooling head. The fixture is in contact with the side of the cooling head.

  According to the present invention, since the fixture is in contact with the side surface of the cooling head, the end of the cooling head can be used more effectively. Thereby, cooling efficiency can be improved.

  Preferably, the heat transfer section has a second heat transfer plate. The second heat transfer plate is attached to the coil portion at a second position away from the first position. The fixture holds both the first heat transfer plate and the second heat transfer plate.

  Thereby, the connection of each of the first and second heat transfer plates to the cooling head can be made with a simple structure while suppressing thermal resistance.

Preferably, the first heat transfer plate is thicker than the second heat transfer plate.
Thereby, the thermal resistance of the first heat transfer plate can be made smaller than that of the second heat transfer plate. Therefore, the heat which arises in the part to which the 1st heat exchanger plate was attached among coil parts can be removed more efficiently with a cooling head.

  The coil portion may have an end portion through which the magnetic flux passes. In this case, the first position is preferably closer to the end portion of the coil portion than the second position.

  As a result, heat can be efficiently removed from the end of the coil portion that is likely to generate more heat due to the vertical magnetic field by the first heat transfer plate having low thermal resistance.

Preferably, the first heat transfer plate is formed by laminating a plurality of single-layer plates.
As a result, the flexibility of the first heat transfer plate is increased, so that the load that the cooling head receives from the coil portion via the first heat transfer plate can be reduced. Therefore, failure of the cooling head due to application of a load from the coil portion can be prevented.

  The superconducting magnet of the present invention includes the superconducting coil and a heat insulating container. The insulated container contains the superconducting coil.

  According to the superconducting magnet of the present invention, the cooling efficiency can be increased while preventing a failure of the cooling head.

  As described above, according to the present invention, the cooling efficiency of the coil portion can be increased.

It is sectional drawing which shows roughly the structure of the superconducting magnet in one embodiment of this invention. It is a figure which shows schematically the structure of the superconducting coil which the superconducting magnet of FIG. 1 has, and is sectional drawing which follows the line II-II of FIG. FIG. 3 is a top view schematically showing the configuration of the superconducting coil of FIG. 2. It is a perspective view which shows schematically the structure of the double pancake coil which the superconducting coil of FIG. 2 has. It is a schematic sectional drawing in alignment with line VV of FIG. It is a partial perspective view which shows roughly the structure of the superconducting wire used for the double pancake coil of FIG. It is a partial perspective view which shows roughly the structure of the cooling head which the superconducting coil of FIG. 2 has. It is a partial cross section figure which shows schematically the structure of the heat exchanger plate which the superconducting coil of FIG. It is a partial cross section figure which shows schematically the structure of the heat exchanger plate which the superconducting coil of FIG. 2 has which consists of a single layer board. It is a top view which shows roughly the structure of the superconducting coil of a modification.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Referring to FIG. 1, superconducting magnet 100 of the present embodiment includes a superconducting coil 91, a heat insulating container 111, a cooling device 121, a hose 122, a compressor 123, a cable 131, and a power source 132. The heat insulating container 111 contains the superconducting coil 91. In the present embodiment, a magnetic field application region SC for storing a sample (not shown) to which a magnetic field is applied is provided in the heat insulating container 111.

  Referring to FIGS. 2 and 3, superconducting coil 91 has a coil portion 10, a cooling head 20, a heat transfer portion 30, and a core portion 81. The heat transfer unit 30 includes a heat transfer plate group 31 and a fixture 32. The heat transfer plate group 31 includes heat transfer plates 31a to 31e.

  The coil portion 10 is formed by winding a superconducting wire 14 (FIG. 6), and is for generating a magnetic flux MF. Moreover, the coil part 10 has the edge part (upper end or lower end in FIG. 2) through which the magnetic flux MF passes. Moreover, the coil part 10 has the double pancake coils 11a-11m. The double pancake coils 11a to 11m are stacked so as to be arranged in this order. The axial direction Aa (FIG. 2) corresponds to the stacking direction, and the radial direction Ar corresponds to a direction perpendicular to the stacking direction.

  The cooling head 20 is for cooling the coil part 10, and has the end part 21 which can be cooled, and the connection part 22 which connects the end part 21 and the cooling device 121 (FIG. 1).

  Each of the heat transfer plate groups 31 is attached to the coil portion 10. The fixture 32 is attached to the end 21 of the cooling head 20. The fixture 32 holds the heat transfer plate group 31. In the portion of the heat transfer plate group 31 held by the fixture 32, the heat transfer plates 31a to 31e are directly stacked on each other. With such a structure, the heat transfer unit 30 connects the coil unit 10 and the cooling head 20 to each other.

  The relative position between the coil unit 10 and the cooling head 20 may vary depending on various factors. The factors include, for example, differences in thermal expansion and contraction, vibrations by the compressor 123 (FIG. 1) for driving the cooling head 20, magnetic interaction between the coil unit 10 and the sample to which a magnetic field is applied by the coil unit 10, and the like. It is. Due to this variation, a load may be applied from the coil unit 10 to the cooling head 20. The load that can be withstood by the cooling head 20 is, for example, about 100 (N).

  The coil unit 10 and the portion attached to the coil unit 10 of the heat transfer plate group 31 have a configuration in which conductive plates and pancake coils are alternately stacked. The heat transfer plate 31a is attached to each position of the double pancake coils 11a and 11m at both ends of the coil portion 10. The heat transfer plate 31b is attached to each position between the double pancake coils 11a and 11b and between the double pancake coils 11m and 11l. The heat transfer plate 31c is attached to each position between the double pancake coils 11b and 11c and between the double pancake coils 11l and 11k. The heat transfer plate 31d is attached to each position between the double pancake coils 11c and 11d and between the double pancake coils 11k and 11j. The heat transfer plate 31e is attached to each position between the double pancake coils 11e and 11f, between the double pancake coils 11j and 11i, and between the double pancake coils 11f and 11g.

  In other words, the heat transfer plates 31 a to 31 e are attached in this order at positions closer to the end of the coil portion 10. In addition, each of the heat transfer plates 31 a to 31 e is attached to positions that are separated from each other in the coil portion 10.

  The material of the heat transfer plates 31a to 31e is preferably a material having high thermal conductivity and flexibility, such as aluminum (Al) or copper (Cu). The purity of Al (or Cu) is preferably 99.9% or higher.

  The heat transfer plates 31 a to 31 e may have a bent portion FD so that the heat transfer plates 31 a to 31 e can extend to the fixture 32.

  The fixture 32 includes members 32a and 32b and screws 34a and 34b. The screw 34a is provided so that the clearance between the members 32a and 32b can be adjusted. The heat transfer plate group 31 is held by the fixture 32 by sandwiching the heat transfer plate group 31 in the gap between the members 32a and 32b and tightening the screw 34a. That is, the heat transfer plates 31 a to 31 e are held by the fixture 32. The screw 34 b is provided so that each of the members 32 a and 32 b can tighten the side surface SD of the end portion 21 of the cooling head 20. As a result, the fixture 32 is attached to the end 21 of the cooling head 20.

  4 and 5, double pancake coil 11a has pancake coils 12a and 12b stacked on each other. The winding direction Wa of the superconducting wire 14 in the pancake coil 12a is opposite to the winding direction Wb of the superconducting wire 14 in the pancake coil 12b. The end portion ECi of the superconducting wire 14 located on the inner peripheral side of the pancake coil 12a and the end portion ECi of the superconducting wire located on the inner peripheral side of the pancake coil 12b are electrically connected to each other. Thereby, between the end ECo of the superconducting wire 14 located on the outer peripheral side of the pancake coil 12a and the end ECo of the superconducting wire 14 located on the outer peripheral side of the pancake coil 12b, the pancake coils 12a and 12b Are connected to each other in series.

  Each of the double pancake coils 11b to 11m has the same configuration as that of the double pancake coil 11a. The ends ECo of the double pancake coils 11a to 11m adjacent to each other are electrically connected to each other. Thereby, the double pancake coils 11a-11m are mutually connected in series.

  Referring to FIG. 6, superconducting wire 14 has a thickness Dt that is a dimension in thickness direction At and a width Dw that is a dimension in axial direction Aa, and extends along extending direction Ae. Yes. The width Dw is larger than the thickness Dt, and thus the superconducting wire 14 has a strip surface SF having the width Dw. The superconducting wire 14 has a characteristic that the AC loss increases as a magnetic field (vertical magnetic field) perpendicular to the band-shaped surface SF is applied.

  For example, the thickness Dt is about 0.2 mm and the width Dw is about 4 mm. For example, the superconducting wire 14 has a Bi-based superconductor extending in the extending direction and a sheath covering the superconductor. The sheath is made of, for example, silver or a silver alloy.

  Referring to FIG. 7, the end portion 21 of the cooling head 20 has an end surface BM and a side surface SD surrounding the end surface BM. The cooling head 20 has, for example, a cylindrical shape.

  Referring to FIG. 8, heat transfer plate 31a may be a laminated plate having a thickness T31a, and is preferably formed by laminating single layer plates 11 having the same thickness. Alternatively, the heat transfer plate 31a may be a single layer plate having a thickness T31. The same applies to each of the heat transfer plates 31b to 31d (FIG. 2). The thickness of each of the heat transfer plates 31a to 31d is preferably larger as it is closer to the end portion (the upper end or the lower end in FIG. 2) of the coil portion 10. The thickness of the heat transfer plates 31a to 31d can be adjusted by, for example, the number of single-layer plates 11 constituting each laminated plate. In this case, the number of stacked layers of the heat transfer plates 31 a to 31 d is larger as the end of the coil unit 10 is closer.

  The thickness of each single-layer board 11 is preferably 1 mm or less, and more preferably 0.5 mm or less in order to ensure sufficient flexibility.

  Referring to FIG. 9, the heat transfer plate 31e preferably has a thickness T31e smaller than the thickness T31a. Preferably, the heat transfer plate 31e is composed of a single single-layer plate 11 as shown in FIG.

  Referring to FIG. 10, a heat transfer plate 31 a V in which insulating portions 41 and 42 for suppressing vortex loss are inserted may be used instead of the above-described heat transfer plate 31 a (FIG. 3). The insulating portion 41 is inserted into a slit formed in the heat transfer plate 31aV along the radial direction of the coil portion 10. The insulating part 42 is inserted into a slit formed in the heat transfer plate 31aV along the circumferential direction of the coil part 10. The material of the insulating parts 41 and 42 is, for example, glass fiber reinforced plastic (GFRP).

  According to the present embodiment, since the fixture 32 is in contact with the side surface SD of the cooling head 20, the end 21 of the cooling head 20 can be used more effectively. Thereby, cooling efficiency can be improved.

  The fixture 32 is attached to the cooling head 20 and holds the heat transfer plates 31a to 31e together. Thereby, the connection of the heat transfer plates 31a to 31e to the cooling head 20 can be made with a simple structure while suppressing thermal resistance.

  Preferably, heat transfer plate group 31 has first and second heat transfer plates, and the first heat transfer plate is thicker than the second heat transfer plate. For example, if the heat transfer plate 31a is the first heat transfer plate, each of the heat transfer plates 31b to 31e corresponds to the second heat transfer plate. Alternatively, if the heat transfer plate 31b is the first heat transfer plate, each of the heat transfer plates 31c to 31e corresponds to the second heat transfer plate. Thereby, the thermal resistance of the first heat transfer plate can be reduced as compared with the second heat transfer plate. Therefore, the heat which arises in the part to which the 1st heat exchanger plate was attached among coil parts 10 can be removed more efficiently by a cooling head.

  Preferably, a first heat transfer plate whose thermal resistance is reduced by being thick is attached to a position near the end of the coil portion 10. Thereby, heat can be efficiently removed from the end portion of the coil portion 10 that is likely to generate more heat due to the vertical magnetic field by the first heat transfer plate having a low thermal resistance.

  Preferably, the first heat transfer plate is formed by laminating a plurality of single-layer plates. As a result, the flexibility of the first heat transfer plate is increased, so that the load that the cooling head receives from the coil portion via the first heat transfer plate can be reduced. Therefore, failure of the cooling head due to application of a load from the coil portion can be prevented.

  The amount of heat generated in each of the double pancake coils 11a to 11m constituting the coil unit 10 was simulated. Moreover, the temperature difference between each of the double pancake coils 11a to 11m and the fixture 32 attached to the cooling head 20 was simulated. The double pancake coil having a large temperature difference becomes higher in temperature. In addition, the value in the side (The coil part 10 right side surface in FIG. 2) from which the heat-transfer board group 31 was pulled out was used for the temperature of the double pancake coils 11a-11m.

  The heat transfer plate group 31 (FIG. 2) was prepared using an Al plate having a thickness of 0.5 mm. As the heat transfer plates 31a to 31d, laminated plates formed by laminating Al plates were used. The number of stacked layers of the heat transfer plates 31a to 31d was 7, 5, 3 and 2, respectively. As the heat transfer plate 31e, an Al plate single layer plate was used. As the material of the Al plate, Al having a purity of 99.999% was used. Between the coil part 10 and the fixture 32, the width (the vertical dimension in FIG. 10) of each of the heat transfer plates 31a to 31e was 50 mm, and the length (the horizontal dimension in FIG. 10) was 200 mm.

  The simulation results are shown below.

  As the double pancake coils 11a to 11m are closer to the end portion of the coil portion 10 (the closer to the uppermost row or the lowermost row in Table 1), the amount of heat increases. As can be seen from the direction of the magnetic flux MF in FIG. 2, the reason is considered to be that the closer to the end of the coil portion 10, the larger the vertical magnetic field becomes.

  The temperature difference between each of the double pancake coils 11a to 11e was approximately 10 (K), and there was no significant difference. That is, the temperature difference between the double pancake coils 11a to 11e was able to be suppressed, although the amount of heat of each of the double pancake coils 11a to 11e was greatly different.

  Moreover, simulation of each thermal resistance of said heat-transfer board group 31 and the fixing tool 32 was also performed. In the portion of the fixture 32 (FIG. 2) that holds the heat transfer plate group 31, each of the members 32a and 32b has a thickness of 42 mm and a length of 50 mm. The material of the fixture 32 was copper. As a result, the heat resistance of the heat transfer plate group 31 was 0.055 (K / W), and the heat resistance of the fixture 32 was 0.005 (K / W). That is, the thermal resistance due to the fixture 32 could be made sufficiently small.

  A load applied to the cooling head 20 was simulated when the distance between the coil unit 10 and the cooling head 20 varied by 1 mm. Since this simulation was performed for the purpose of investigating the effect of using a laminated plate in the heat transfer plate group 31, each of the heat transfer plates 31a to 31e has the same configuration under each simulation condition. .

  In addition to the case where the Al plate described above was used as the heat transfer plate group 31, this simulation was also performed when a Cu plate was used. The number of stacking conditions was three. The first condition corresponds to a laminated plate having six laminated layers and six single-layered plates having a thickness of 0.5 mm. The second condition corresponds to a laminated plate having three laminated layers and three single-layered plates having a thickness of 1.0 mm. The third condition corresponds to a single-layer plate having a stack number of 1 and a thickness of 3.0 mm. The results are shown below.

  From this result, it is understood that the load applied to the cooling head 20 can be reduced by increasing the number of layers while ensuring the total thickness of each heat transfer plate (in this case, maintaining the thickness of 3 mm). It was.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is shown not by the above-described embodiment but by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

  DESCRIPTION OF SYMBOLS 10 Coil part, 11a-11m Double pancake coil, 11 Single layer board, 12a, 12b Pancake coil, 14 Superconducting wire, 20 Cooling head, 21 End part, 22 Connection part, 30 Heat transfer part, 31 Heat transfer plate group , 31a to 31e, 31aV Heat transfer plate, 32 fixing member, 32a, 32b member, 41, 42 insulation part, 81 core part, 91 superconducting coil, 100 superconducting magnet, 111 heat insulation container, 121 cooling device, 123 compressor, 132 power supply , BM end face, FD bent portion, SC magnetic field application region, SD side face, SF band-like face.

Claims (6)

A coil portion formed by winding a superconducting wire;
A columnar cooling head having a coolable end,
The end portion of the cooling head has an end surface and a side surface surrounding the end surface, and further includes a heat transfer portion that connects the coil portion and the cooling head to each other,
Said heat transfer unit comprises a first and a heat transfer plate which is mounted in the first position to the coil portion, and a fixture for gripping said mounted on the cooling head and the first heat transfer plate, wherein fixture has a through portion, the through portion of the fixture is in contact with the side surface of the columnar cooling head, the superconducting coil. The heat transfer part includes a second heat transfer plate attached to the coil part at a second position away from the first position,
The superconducting coil according to claim 1, wherein the fixture holds both the first heat transfer plate and the second heat transfer plate.   The superconducting coil according to claim 2, wherein the first heat transfer plate is thicker than the second heat transfer plate.   The superconducting coil according to claim 3, wherein the coil portion has an end portion through which magnetic flux passes, and the first position is closer to the end portion than the second position. The first heat transfer plate, a plurality of single-layer plate is formed by laminating superconducting coil according to any one of claims 1 to 4. The superconducting coil according to any one of claims 1 to 5 ,
A superconducting magnet comprising a heat insulating container in which the superconducting coil is housed.

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