High-temperature superconducting coils and high-temperature superconducting coil laminates

Abstract

This technology increases the strength of high-temperature superconducting wires against thermal stress and prevents degradation, while also increasing the current density of high-temperature superconducting coils to achieve higher magnetic fields. [Solution] A high-temperature superconducting coil 10 is formed by winding a high-temperature superconducting wire 11, which is configured such that a crystal-oriented intermediate layer 13 is arranged on a tape-shaped metal substrate 12, a crystal-oriented superconducting layer 14 is arranged on the intermediate layer, the superconducting layer is covered by a first metal layer 15 as a protective layer, the entire structure including the first metal layer is covered by a second metal layer 16 as a stabilizing layer, and a third metal layer 17 having higher strength than the second metal layer is covered on the second metal layer, and the third metal layer 17 of the high-temperature superconducting wire is made thicker in the positions corresponding to the parts of the high-temperature superconducting coil where strength is required compared to other parts.

Description

Technical Field

[0001] Embodiments of the present invention relate to high-temperature superconducting coils and high-temperature superconducting coil laminates.

Background Art

[0002] The REBCO (REBa2Cu3O y7-δ ) high-temperature superconducting wire 1, conventionally, as shown in FIG. 9, a crystalline orientation intermediate layer 3 and a superconducting layer 4 are sequentially formed in layers on a tape-shaped metal substrate 2 responsible for strength. Further, in order to prevent the degradation of the superconducting layer 4 by air or water, a first metal layer (protective layer) 5 is arranged so as to surround the superconducting layer 4. Furthermore, a second metal layer (stabilizing layer) 6 is arranged so as to cover the first metal layer 5 so that the superconducting layer 4 is not burned out by the bypass current during quenching. The tape-shaped high-temperature superconducting wire 1 configured as described above is wound spirally from the inside to form a pancake shape and fixed to form a high-temperature superconducting coil 7. This high-temperature superconducting coil 7 may be wound into a shape other than the pancake shape depending on the application.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0004] Structurally, the high-temperature superconducting coil 7 is mechanically weak against the direction in which the superconducting layer 4 of the high-temperature superconducting wire 1 peels off. Therefore, measures have been taken to suppress strain stress against thermal stress during cooling and electromagnetic forces (hoop force, axial compression force) during energization. For example, Patent Document 1 describes how the deterioration of the superconducting layer caused by internal stress generated when the high-temperature superconducting coil is cooled to extremely low temperatures is prevented by applying an insulating tape between the high-temperature superconducting wires during winding of the high-temperature superconducting coil, or by applying a release treatment to the surface of the high-temperature superconducting wire itself to weaken the adhesion with the epoxy resin that fixes the high-temperature superconducting coil. Furthermore, Patent Document 2 describes how the outer circumference of the high-temperature superconducting wire is reinforced with a C-shaped metal to increase the strength of the upper surface of the superconducting layer, making it less prone to movement and preventing the peeling of the superconducting layer.

[0005] Patent Document 3 describes a configuration in which two high-temperature superconducting wires are stacked and connected at both ends in the width direction with solder or the like, so that when subjected to thermal stress, the force is borne only at these ends. In the width direction, there is no connection to adjacent high-temperature superconducting wires in the central part, so the thermal stress is divided among each high-temperature superconducting wire, and peeling stress hardly acts on the superconducting layer of the high-temperature superconducting wire. Furthermore, Patent Document 4 describes a configuration in which the entire circumference of the high-temperature superconducting wire is reinforced with an alloy (such as NiP) that is stronger than the outer Cu plating (stabilizing layer), thereby reducing peeling stress during thermal shrinkage and deformation due to electromagnetic force, making the superconducting layer of the high-temperature superconducting wire less prone to deterioration.

[0006] High-temperature superconducting wires, or high-temperature superconducting coils formed by winding them, are prone to deformation and degradation due to thermal stress and electromagnetic forces. When using a method to avoid deformation by reinforcing them with a high-strength alloy, as described in Patent Document 4, there is a problem in that the volume that does not contribute to the current increases, resulting in a decrease in current density.

[0007] Furthermore, in high-temperature superconducting coils formed by fixing high-temperature superconducting wires using a certain method, a release agent is applied to some of the components to reduce the number of fixed points in order to relieve thermal stress, thereby suppressing the deterioration of the superconducting layer of the high-temperature superconducting wire. However, in configurations where the high-temperature superconducting wire is connected to materials such as winding frames and electrodes, fixing the high-temperature superconducting wire to the winding frames, etc., may be necessary due to requirements for strength and heat transfer, and there are places where stress relief by release agents cannot be implemented. In addition, since the winding frames and electrodes are made of different materials from the materials that constitute the high-temperature superconducting wire, the difference in the coefficient of linear expansion between the high-temperature superconducting wire and the winding frames, etc. makes it easy for stress to occur in the high-temperature superconducting wire due to temperature changes, and localized deterioration of the superconducting layer may occur in the high-temperature superconducting wire at the points where it is in contact with the winding frames, etc.

[0008] The embodiments of the present invention have been made in consideration of the above circumstances, and aim to provide a high-temperature superconducting coil and a high-temperature superconducting coil laminate that can increase the strength of the high-temperature superconducting wire against thermal stress and the like to prevent deterioration, and can also increase the current density of the high-temperature superconducting coil to achieve a high magnetic field. [Means for solving the problem]

[0009] The high-temperature superconducting coil in an embodiment of the present invention is formed by winding a first high-temperature superconducting wire, which is configured such that a crystal-oriented intermediate layer is arranged in layers on a tape-shaped metal substrate, and a crystal-oriented superconducting layer is arranged on the intermediate layer, the superconducting layer is covered by a first metal layer as a protective layer, and the entire structure including the first metal layer is covered by a second metal layer as a stabilizing layer, or a second high-temperature superconducting wire, which is configured such that a third metal layer having higher strength than the second metal layer is covered on the second metal layer, wherein the thickness of the second metal layer of the first high-temperature superconducting wire or the thickness of the third metal layer of the second high-temperature superconducting wire is provided to be thicker in the position corresponding to the part of the high-temperature superconducting coil where strength is required, compared to the position corresponding to the other part.

[0010] The high-temperature superconducting coil laminate in the embodiment of the present invention is a high-temperature superconducting coil laminate in which a plurality of high-temperature superconducting coils are stacked in the axial direction, wherein a first high-temperature superconducting wire is formed by winding a first high-temperature superconducting wire, which is formed by winding a first high-temperature superconducting wire, which is formed by winding a second high-temperature superconducting wire, which is formed by winding a second high-temperature superconducting wire, which is formed by winding a second high-temperature superconducting wire, which is formed by winding a first first high-temperature superconducting wire, which is formed by winding a first high-temperature superconducting wire, which is formed by winding a second high-temperature superconducting wire, which is formed by winding a first high-temperature superconducting wire, which is formed by winding a second high-temperature superconducting wire, which is formed by winding a first high-temperature superconducting wire, which is formed by winding a first high-temperature superconducting wire, which is formed by winding a second high-temperature superconducting wire, which is formed by winding a first high-temperature superconducting wire, which is formed by winding a first high-temperature superconducting wire, which is formed by winding a second [Effects of the Invention]

[0011] According to embodiments of the present invention, the strength of the high-temperature superconducting wire can be increased against thermal stress and other factors to prevent deterioration, and the current density of the high-temperature superconducting coil can be increased to achieve a high magnetic field. [Brief explanation of the drawing]

[0012] [Figure 1] A schematic cross-sectional view showing a high-temperature superconducting coil according to the first embodiment. [Figure 2] A schematic cross-sectional view showing a high-temperature superconducting coil according to the second embodiment. [Figure 3] A schematic cross-sectional view showing a high-temperature superconducting coil according to the third embodiment. [Figure 4] A schematic diagram showing a high-temperature superconducting coil laminate according to the fourth embodiment. [Figure 5] Figure 4 shows a high-temperature superconducting coil laminate, where (A) is a longitudinal section view and (B) is a view taken along the VB arrow in Figure 5(A). [Figure 6] A schematic cross-sectional view showing a high-temperature superconducting coil laminate according to the fifth embodiment. [Figure 7] A schematic cross-sectional view showing a high-temperature superconducting coil in the first comparative configuration. [Figure 8] Schematic cross-sectional view showing a high-temperature superconducting coil laminate of the second comparison form. [Figure 9] Schematic cross-sectional view showing a conventional high-temperature superconducting coil.

Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments for carrying out the present invention will be described based on the drawings. [A] First Embodiment (FIG. 1) FIG. 1 is a schematic cross-sectional view showing a high-temperature superconducting coil according to the first embodiment. The high-temperature superconducting coil 10 shown in this FIG. 1 is formed, for example, in a pancake shape by winding a single high-temperature superconducting wire 11 spirally from the inside, and generates a magnetic field when the high-temperature superconducting wire 11 is energized. In this high-temperature superconducting coil 10, the whole may be fixed with an epoxy resin, an insulating material may be sandwiched between the high-temperature superconducting wires 11 and co-wound with the high-temperature superconducting wires 11, or an insulating layer may be applied to the high-temperature superconducting wires 11 themselves.

[0014] The high-temperature superconducting wire 11 has an intermediate layer 13 with crystal orientation on a tape-shaped metal substrate 12, and a superconducting layer 14 with crystal orientation on this intermediate layer 13, which are arranged in layers respectively. The superconducting layer 14 is covered by a first metal layer 15 as a protective layer, and the whole including this first metal layer 15 is covered by a second metal layer 16 as a stabilizing layer. On the second metal layer 16, it is configured by being covered by a third metal layer 17 having a higher strength than the second metal layer 16. This high-temperature superconducting wire 11 is the second high-temperature superconducting wire of claim 1.

[0015] The first metal layer 15 as a protective layer prevents the deterioration of the superconducting layer 14 by not allowing air or water to permeate, and usually, silver (Ag) is used. Since this silver is expensive, it is set to the minimum thickness (about several nm) necessary for preventing the deterioration of the superconducting layer 14.

[0016] The second metal layer 16 as the stabilization layer is a layer that serves as a current bypass path so that when the high-temperature superconducting wire 11 quenches, the superconducting layer 14 is not damaged by the bypass current during quenching. This second metal layer 16 is selected to have an electrical resistance that does not burn out when the quench current bypasses, and usually, copper (Cu) is closely applied to cover the first metal layer 15 with a thickness of about several μm to several tens of nm. This second metal layer 16 is formed by a plating process.

[0017] The third metal layer 17 has a reinforcing function. As long as the material has a higher strength than the second metal layer 16 (for example, higher hardness, Young's modulus or yield stress than the second metal layer 16), the reinforcing effect is improved compared to the case where the second metal layer 16 is thickened. Considering the adhesion of this third metal layer 17 to the copper (Cu) of the second metal layer 16, Cu alloys, Ni, Ni alloys, Cr, Cr alloys, etc. are effective. Furthermore, due to the demand for non-magnetism that is less affected in a magnetic field, NiP is effective for the third metal layer 17. This third metal layer 17 is also formed by a plating process.

[0018] By the way, when a high-temperature superconducting coil is formed using a high-temperature superconducting wire reinforced by the third metal layer 17, in the high-temperature superconducting coil, a portion with a high load (for example, a portion near the center in the radial direction of the high-temperature superconducting coil) and a portion with a low load (for example, both ends on the inner or outer side in the radial direction of the high-temperature superconducting coil) occur. In this case, as shown in FIG. 7, if the third metal layer 17 of the high-temperature superconducting wire 101 forming the high-temperature superconducting coil 100 has the same thickness in the longitudinal direction of the high-temperature superconducting wire 101, the high-temperature superconducting wire 101 will be designed based on the portion with the highest load in the high-temperature superconducting coil 100, so that excessive strength will occur in most parts of the high-temperature superconducting coil 100.

[0019] Therefore, as shown in Figure 1, the high-temperature superconducting wire 11 forming the high-temperature superconducting coil 10 of this first embodiment is designed such that the thickness of the third metal layer 17 is greater in the area corresponding to the part of the high-temperature superconducting coil 10 where strength is required (for example, the area near the radial center of the high-temperature superconducting coil 10) compared to the area corresponding to other parts (for example, the radially inner or outer ends of the high-temperature superconducting coil 10).

[0020] In other words, in a single high-temperature superconducting wire 11, the thickness of the third metal layer 17 changes continuously at each position along the longitudinal direction of the high-temperature superconducting wire 11, resulting in a thickness distribution. As shown in the cross-section 11A, the third metal layer 17 is thickest at the position corresponding to the part of the high-temperature superconducting coil 10 where strength is required (for example, the part near the radial center of the high-temperature superconducting coil 10), and as shown in the cross-section 11B, the third metal layer 17 is thin at the position corresponding to the part of the high-temperature superconducting coil 10 where strength is not required (for example, the radial inner or outer end of the high-temperature superconducting coil 10).

[0021] The third metal layer 17 of the high-temperature superconducting wire 11 is formed by plating as described above. During this deposition process, the thickness of the third metal layer 17 can be continuously varied at each position along the longitudinal direction of the high-temperature superconducting wire 11 by adjusting the current density to the plating bath or the sweeping speed of the high-temperature superconducting wire 11 passing through the plating bath. In other words, the thickness of the third metal layer 17 is set by increasing the current density to the plating bath at positions where the thickness of the third metal layer 17 of the high-temperature superconducting wire 11 is desired, and decreasing it at positions where the thickness of the third metal layer 17 of the high-temperature superconducting wire 11 is desired. Alternatively, the thickness of the third metal layer 17 may be set by slowing down the sweeping speed of the high-temperature superconducting wire 11 passing through the plating bath at positions where the thickness of the third metal layer 17 of the high-temperature superconducting wire 11 is desired, and speeding it up at positions where the thickness of the third metal layer 17 of the high-temperature superconducting wire 11 is desired.

[0022] As configured as described above, this first embodiment provides the following effects (1) to (3). (1) In the areas of the high-temperature superconducting coil 10 where strength is required (for example, the area near the radial center of the high-temperature superconducting coil 10), the thickness of the third metal layer 17 of the high-temperature superconducting wire 11 is made thicker than in the areas of other areas (for example, the radial inner or outer ends of the high-temperature superconducting coil 10). As a result, in the areas of the high-temperature superconducting coil 10 where strength is required, the strength of the high-temperature superconducting wire 11 is increased against thermal stress during cooling and electromagnetic force during energization, preventing deformation, and thus preventing deterioration of the high-temperature superconducting wire 11, especially deterioration of the superconducting layer 14.

[0023] (2) In the areas corresponding to other parts of the high-temperature superconducting coil 10 where strength is not required (for example, the radially inner or outer ends of the high-temperature superconducting coil 10), the thickness of the third metal layer 17 of the high-temperature superconducting wire 11 is made thinner than in the areas corresponding to the parts where strength is required. As a result, the number of turns of the high-temperature superconducting wire 11 is increased, the current density of the high-temperature superconducting coil 10 is increased, and a high magnetic field can be achieved.

[0024] (3) The third metal layer 17 of the high-temperature superconducting wire 11 is formed by a plating process, and by adjusting the current density to the plating bath or the sweeping speed of the high-temperature superconducting wire 11 passing through the plating bath during this deposition process, the thickness of the third metal layer 17 is continuously varied at each position in the longitudinal direction of the high-temperature superconducting wire 11. As a result, a high-temperature superconducting wire 11 with a thickness of the third metal layer 17 varying in the longitudinal direction can be easily manufactured, and a high-temperature superconducting coil 10 with varying strength in parts where strength is required and parts where it is not can be easily manufactured.

[0025] [B] Second embodiment (Figure 2) Figure 2 is a schematic cross-sectional view showing a high-temperature superconducting coil according to the second embodiment. In this second embodiment, parts that are the same as in the first embodiment are denoted by the same reference numerals as in the first embodiment, and their description is simplified or omitted.

[0026] The difference between the high-temperature superconducting coil 20 of this second embodiment and the first embodiment is that the portion of the high-temperature superconducting coil 20 where strength is required is the portion where the high-temperature superconducting wire 21 comes into contact with (for example, is fixed to) a member (for example, a winding frame 22) that has a different coefficient of thermal expansion than the high-temperature superconducting wire 21. Therefore, the high-temperature superconducting wire 21 is provided such that the thickness of the third metal layer 17 is greatest at the position corresponding to the portion of the high-temperature superconducting coil 20 that comes into contact with (for example, is fixed to) the winding frame 22 where strength is required.

[0027] In other words, a component (for example, a reel 22) with a different coefficient of thermal expansion than the high-temperature superconducting wire 21 is placed inside the high-temperature superconducting coil 20, and when thermal stress increases due to the difference in coefficient of thermal expansion at the part that contacts (for example, is fixed to) this component, the thickness of the third metal layer 17 of the high-temperature superconducting wire 21 is made thickest at the position corresponding to the part that contacts (for example, is fixed to) the reel 22, as shown in cross-sectional section 21A of Figure 2, compared to other positions (see cross-sectional sections 21B and 21C of Figure 2).

[0028] As configured as described above, this second embodiment provides the same effects as the first embodiment (2) and (3), as well as the following effect (4).

[0029] (4) When a component with a different coefficient of thermal expansion than the high-temperature superconducting wire 21 (for example, a winding frame 22) is placed inside the high-temperature superconducting coil 20, the thickness of the third metal layer 17 of the high-temperature superconducting wire 21 is made thickest at the position corresponding to the part that contacts (for example, is fixed to) the winding frame 22 compared to other positions. Therefore, in the high-temperature superconducting wire 21 that contacts (for example, is fixed to) the winding frame 22 inside the high-temperature superconducting coil 20, deformation due to thermal stress caused by the difference in coefficient of thermal expansion is prevented, and deterioration, in particular deterioration of the superconducting layer 14, can be prevented. From the viewpoint of strength and heat transfer, when the high-temperature superconducting wire 21 is fixed to a winding frame 22 with a different coefficient of thermal expansion as described above, the effect of preventing deterioration due to the thickness of the third metal layer 17 is significantly greater compared to when it is not fixed.

[0030] [C] Third embodiment (Figure 3) Figure 3 is a schematic cross-sectional view showing a high-temperature superconducting coil according to the third embodiment. In this third embodiment, parts similar to those in the first embodiment are denoted by the same reference numerals as in the first embodiment, thereby simplifying or omitting their description.

[0031] The difference between the high-temperature superconducting coil 30 of this third embodiment and the first embodiment is that the high-temperature superconducting wire 31 forming the high-temperature superconducting coil 30 does not have a third metal layer 17, and the thickness of the second metal layer 16 is set to be thicker in the position corresponding to the part of the high-temperature superconducting coil 30 where strength is required (for example, the part near the radial center of the high-temperature superconducting coil 30), as shown in the cross-sectional portion 31A, compared to the position corresponding to other parts where strength is not required (for example, the radially inner or outer end of the high-temperature superconducting coil 30) (see cross-sectional portion 31B). The high-temperature superconducting wire 31 is the first high-temperature superconducting wire of claim 1.

[0032] In other words, a single high-temperature superconducting wire 31 has a thickness distribution in which the thickness of the second metal layer 16 continuously changes at each position in the longitudinal direction, and the thickness of the second metal layer 16 is thickest at a position corresponding to, for example, the radial center, where the strength of the high-temperature superconducting coil 30 is required. The second metal layer 16 of this high-temperature superconducting wire 31 is also formed by a plating process, and by adjusting the current density into the plating bath or the sweeping speed of the high-temperature superconducting wire 31 passing through the plating bath, the thickness is made to continuously change at each position in the longitudinal direction of the high-temperature superconducting wire 31. When this single high-temperature superconducting wire 31 is wound in a spiral shape, the high-temperature superconducting coil 30 is formed, for example, in a pancake shape.

[0033] As configured as described above, this third embodiment provides the following effects (5) to (7). (5) In the areas of the high-temperature superconducting coil 30 where strength is required (for example, the area near the radial center of the high-temperature superconducting coil 30), the thickness of the second metal layer 16 of the high-temperature superconducting wire 31 is made thicker than in the areas of other areas (for example, the radial inner or outer ends of the high-temperature superconducting coil 30). As a result, in the areas of the high-temperature superconducting coil 30 where strength is required, the strength of the high-temperature superconducting wire 31 is increased against thermal stress during cooling and electromagnetic force during energization, preventing deformation, and thus preventing deterioration of the high-temperature superconducting wire 31, especially deterioration of the superconducting layer 14.

[0034] (6) In the areas corresponding to other parts of the high-temperature superconducting coil 30 where strength is not required (for example, the radially inner or outer ends of the high-temperature superconducting coil 30), the thickness of the second metal layer 16 of the high-temperature superconducting wire 31 is made thinner than in the areas corresponding to the parts where strength is required. As a result, the number of turns of the high-temperature superconducting wire 31 is increased, the current density of the high-temperature superconducting coil 30 is increased, and a high magnetic field can be achieved.

[0035] (7)(3) The second metal layer 16 of the high-temperature superconducting wire 31 is formed by a plating process, and by adjusting the current density to the plating bath or the sweeping speed of the high-temperature superconducting wire 31 passing through the plating bath during this film formation, the thickness of the second metal layer 16 is provided to change continuously at each position in the longitudinal direction of the high-temperature superconducting wire 31. As a result, a high-temperature superconducting wire 31 in which the thickness of the second metal layer 16 is varied in the longitudinal direction of the high-temperature superconducting wire 31 can be easily manufactured, and a high-temperature superconducting coil 30 with different strengths in parts where strength is required and parts where it is not is easily manufactured.

[0036] [D] Fourth embodiment (Figures 4 and 5) Figure 4 is a schematic diagram showing a high-temperature superconducting coil laminate according to the fourth embodiment. In this fourth embodiment, parts that are the same as in the first embodiment are denoted by the same reference numerals as in the first embodiment, and their explanation is simplified or omitted.

[0037] As shown in Figures 4 and 5, the high-temperature superconducting coil laminate 40M of this fourth embodiment has multiple high-temperature superconducting coils 40 stacked in the axial direction, with the ends of each high-temperature superconducting coil 40 connected by an inner connecting electrode 42 and an outer connecting electrode 43, and lead electrodes 44 connected to the ends of the high-temperature superconducting coils 40 at both ends in the stacking direction. When each high-temperature superconducting coil 40 is energized using these inner connecting electrodes 42, outer connecting electrodes 43 and lead electrodes 44, a magnetic field is generated in each high-temperature superconducting coil 40, and the high-temperature superconducting coil laminate 40M generates a high magnetic field by the superposition of these magnetic fields.

[0038] Here, the comparative high-temperature superconducting coil laminate 100M shown in Figure 8 is constructed by stacking multiple high-temperature superconducting coils 100 shown in Figure 7 in the axial direction, and each of the multiple high-temperature superconducting coils 100 is formed by winding a high-temperature superconducting wire 101 in which a third metal layer 17 of the same thickness is provided in the longitudinal direction of the high-temperature superconducting wire 101, and forming it into a pancake shape, for example.

[0039] In contrast, in the high-temperature superconducting coil laminate 40M of this fourth embodiment, the thickness of the third metal layer 17 or the second metal layer 16 in the high-temperature superconducting wire 41 that forms one high-temperature superconducting coil 40 is the same (uniform) in the longitudinal direction of the high-temperature superconducting wire 41. However, the thickness of the third metal layer 17 or the second metal layer 16 of the high-temperature superconducting wire 41 that forms the high-temperature superconducting coil 40 on the central side of the laminate direction where the load is large in the high-temperature superconducting coil laminate 40M is set to be thicker than the thickness of the third metal layer 17 or the second metal layer 16 of the high-temperature superconducting wire 41 that forms the high-temperature superconducting coil 40 on both ends of the laminate direction where the load is small in the high-temperature superconducting coil laminate 40M.

[0040] The aforementioned load is the axial compressive force that acts as an electromagnetic force in the axial direction of the high-temperature superconducting coil laminate 40M when the high-temperature superconducting coil laminate 40M is energized. This axial compressive force acts most strongly on the high-temperature superconducting coil 40 on the central side in the lamination direction of the high-temperature superconducting coil laminate 40M.

[0041] As configured as described above, this fourth embodiment provides the following effect (8). (8) In the high-temperature superconducting coil laminate 40M, the thickness of the third metal layer 17 or second metal layer 16 of the high-temperature superconducting wire 41 that forms the high-temperature superconducting coil 40 on the central side in the stacking direction where the load is large is set to be thicker than the thickness of the third metal layer 17 or second metal layer 16 of the high-temperature superconducting wire 41 that forms the high-temperature superconducting coil 40 on both ends in the stacking direction where the load is small. As a result, the high-temperature superconducting wire 41 that forms the high-temperature superconducting coil 40 on the central side in the stacking direction of the high-temperature superconducting coil laminate 40M is reinforced by the thicker third metal layer 17 or second metal layer 16, thereby preventing deformation and, in particular, preventing deterioration of the superconducting layer 14. Furthermore, in the high-temperature superconducting coil laminate 40M, the high-temperature superconducting wire 41 is made thinner, which increases the number of turns of the high-temperature superconducting wire 41, thereby increasing the current density and enabling a higher magnetic field.

[0042] [E] Fifth embodiment (Figure 6) Figure 6 is a schematic cross-sectional view showing a high-temperature superconducting coil laminate according to the fifth embodiment. In this fifth embodiment, parts that are the same as in the first embodiment are denoted by the same reference numerals as in the first embodiment, and their description is simplified or omitted.

[0043] In the high-temperature superconducting coil laminate 50M of this fifth embodiment, the thickness of the third metal layer 17 or the second metal layer 16 of the high-temperature superconducting wire 51 forming the high-temperature superconducting coil 50 is such that the high-temperature superconducting coil 50 on the central side of the laminate direction, where the load is greater, is thicker than the high-temperature superconducting coils 50 on both ends of the laminate direction, where the load is smaller, similar to the fourth embodiment. Furthermore, in the same high-temperature superconducting coil 50, similar to the first to third embodiments, the position corresponding to the part where strength is required is thicker than the position corresponding to other parts where strength is less required.

[0044] Here, the above load refers to the axial compressive force that acts as an electromagnetic force in the axial direction of the high-temperature superconducting coil laminate 50M when current is supplied to the high-temperature superconducting coil laminate 50M. This axial compressive force acts most strongly on the high-temperature superconducting coil 50 on the central side in the lamination direction of the high-temperature superconducting coil laminate 50M.

[0045] Furthermore, the parts of each high-temperature superconducting coil 50 where strength is required are the portion near the radial center of the high-temperature superconducting coil 50, or the portion where the high-temperature superconducting wire 51 comes into contact with (for example, is fixed to) a member with a different coefficient of linear expansion. Therefore, the high-temperature superconducting wire 51 forming the high-temperature superconducting coil 50 has a thickness distribution where the thickness of the third metal layer 17 or the second metal layer 16 (for example, the third metal layer 17) changes at each position in the longitudinal direction, and the thickness of the third metal layer 17 or the second metal layer 16 (for example, the third metal layer 17) is thickest at the position corresponding to the portion of the high-temperature superconducting coil 50 where strength is required.

[0046] As configured as described above, this fifth embodiment provides the same effect as the fourth embodiment (8), as well as the following effect (9).

[0047] (9) In the high-temperature superconducting coil 50 on the central side in the stacking direction of the high-temperature superconducting coil laminate 50M, the third metal layer 17 or second metal layer 16 (for example, the third metal layer 17) of the high-temperature superconducting wire 51 is made thicker overall compared to the high-temperature superconducting coils 50 on both ends in the stacking direction, and is made thicker at a position corresponding to the radial center portion of the high-temperature superconducting coil 50 on the central side in the stacking direction than at a position corresponding to the radial ends.

[0048] Furthermore, in the high-temperature superconducting coil laminate 50M, the high-temperature superconducting coils 50 at both ends in the stacking direction have a third metal layer 17 or second metal layer 16 (for example, the third metal layer 17) of the high-temperature superconducting wire 51 that is thinner overall compared to the high-temperature superconducting coil 50 at the center in the stacking direction. In addition, the high-temperature superconducting coils 50 at both ends in the stacking direction have a position corresponding to the radial center that is thicker than the positions corresponding to both ends in the radial direction.

[0049] Based on these considerations, the high-temperature superconducting wires 51 forming each high-temperature superconducting coil 50 in the high-temperature superconducting coil laminate 50M are reinforced by providing a thicker third metal layer 17 or second metal layer 16 (for example, the third metal layer 17) at positions corresponding to the parts of the high-temperature superconducting coil 50 where strength is required (for example, the part near the radial center of the high-temperature superconducting coil 50). This prevents deformation due to thermal stress or electromagnetic force, thereby reliably preventing deterioration, especially deterioration of the superconducting layer 14.

[0050] Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be carried out in various other forms, and various omissions, substitutions, modifications, and combinations can be made without departing from the spirit of the invention, and such substitutions, modifications, and combinations are included in the scope and spirit of the invention, as well as in the claims and their equivalents.

[0051] For example, in the high-temperature superconducting coils 10, 20, 30, 40, and 50 of the above-described embodiments, release surfaces may be provided to alleviate thermal shrinkage stress during cooling, or layers of high-temperature superconducting wire may be fixed with conductive resin to serve as a path for bypass current during quenching. Furthermore, each high-temperature superconducting coil 40 of the high-temperature superconducting coil laminate 40M, or each high-temperature superconducting coil 50 of the high-temperature superconducting coil laminate 50M, may be fixed with this conductive resin. [Explanation of symbols]

[0052] 10... High-temperature superconducting coil, 11... High-temperature superconducting wire, 12... Metal substrate, 13... Intermediate layer, 14... Superconducting layer, 15... First metal layer, 16... Second metal layer, 17... Third metal layer, 20... High-temperature superconducting coil, 21... High-temperature superconducting wire, 22... Winding frame, 30... High-temperature superconducting coil, 31... High-temperature superconducting wire, 40M... High-temperature superconducting coil laminate, 40... High-temperature superconducting coil, 41... High-temperature superconducting wire, 50M... High-temperature superconducting coil laminate, 50... High-temperature superconducting coil, 51... High-temperature superconducting wire.

Claims

1. A first high-temperature superconducting wire is formed by winding a second high-temperature superconducting wire, which third metal layer having higher strength than the second metal layer onto the second metal layer, with a crystal-oriented intermediate layer arranged in layers on a tape-shaped metal substrate, a crystal-oriented superconducting layer on top of the intermediate layer, the superconducting layer being covered by a first metal layer as a protective layer, and the entire structure including the first metal layer being covered by a second metal layer, or a second high-temperature superconducting wire being formed by winding a second high-temperature superconducting wire, which is formed by winding a third metal layer having higher strength than the second metal layer onto the second metal layer. A high-temperature superconducting coil characterized in that, in the position corresponding to the part of the high-temperature superconducting coil in which strength is required, the thickness of the second metal layer of the first high-temperature superconducting wire, or the thickness of the third metal layer of the second high-temperature superconducting wire, is provided to be thicker than in the position corresponding to the other part.

2. The high-temperature superconducting coil according to claim 1, characterized in that the portion requiring the aforementioned strength is the portion near the radial center of the high-temperature superconducting coil, or the portion in which the first high-temperature superconducting wire or the second high-temperature superconducting wire comes into contact with a member having a different coefficient of linear expansion.

3. The first high-temperature superconducting wire has a thickness distribution in which the thickness of the second metal layer varies at each position in the longitudinal direction, and the thickness of the second metal layer is thickest at the position corresponding to the part of the high-temperature superconducting coil where strength is required. The high-temperature superconducting coil according to claim 1, characterized in that the second high-temperature superconducting wire has a thickness distribution where the thickness of the third metal layer varies at each position in the longitudinal direction, and the thickness of the third metal layer is thickest at the position corresponding to the part of the high-temperature superconducting coil where strength is required.

4. The high-temperature superconducting coil according to claim 3, characterized in that the second metal layer and the third metal layer are formed by a plating process, and by adjusting the current density to the plating bath or the sweeping speed of the first high-temperature superconducting wire and the second high-temperature superconducting wire, the thickness of the second metal layer of the first high-temperature superconducting wire and the thickness of the third metal layer of the second high-temperature superconducting wire are both provided to vary at each position in the longitudinal direction.

5. The high-temperature superconducting coil according to claim 1, characterized in that the second metal layer is made of Cu and the third metal layer is made of Ni, Ni alloy, Cu alloy, Cr, or Cr alloy.

6. A high-temperature superconducting coil laminate is constructed by stacking multiple high-temperature superconducting coils in the axial direction, each coil being formed by winding a first high-temperature superconducting wire, where a first high-temperature superconducting wire is formed by winding a first high-temperature superconducting wire, where a second high-temperature superconducting wire is formed by winding a second high-temperature superconducting wire, where a third metal layer having higher strength than the second metal layer is wound on top of the second metal layer, and a crystal-oriented intermediate layer is arranged in layers on top of the tape-shaped metal substrate, and a crystal-oriented superconducting layer is arranged on top of the intermediate layer, and the superconducting layer is covered by a first metal layer as a protective layer, and the entire structure including the first metal layer is covered by a second metal layer as a stabilizing layer, or a high-temperature superconducting coil laminate is constructed by winding multiple high-temperature superconducting coils in the axial direction, A high-temperature superconducting coil laminate characterized in that, among the high-temperature superconducting coils, the high-temperature superconducting coil on the central side in the stacking direction has a thicker second metal layer on the first high-temperature superconducting wire, or a thicker third metal layer on the second high-temperature superconducting wire, compared to the high-temperature superconducting coil on the end side in the stacking direction.

7. The high-temperature superconducting coil laminate according to claim 6, characterized in that, in the high-temperature superconducting coil on the central side in the stacking direction and the high-temperature superconducting coil on the end side in the stacking direction, the thickness of the second metal layer of the first high-temperature superconducting wire or the thickness of the third metal layer of the second high-temperature superconducting wire is set to be thicker in the position corresponding to the part where strength is required compared to the position corresponding to other parts.

8. The high-temperature superconducting coil laminate according to claim 7, characterized in that the portion requiring the aforementioned strength is the portion near the radial center of the high-temperature superconducting coil, or the portion in which the first high-temperature superconducting wire or the second high-temperature superconducting wire comes into contact with a member having a different coefficient of linear expansion.

9. The first high-temperature superconducting wire has a thickness distribution in which the thickness of the second metal layer varies at each position in the longitudinal direction, and the thickness of the second metal layer is thickest at the position corresponding to the part of the high-temperature superconducting coil where strength is required. The high-temperature superconducting coil laminate according to claim 7, characterized in that the thickness of the third metal layer of the second high-temperature superconducting wire is distributed with varying thickness at each position in the longitudinal direction, and the thickness of the third metal layer is greatest at the position corresponding to the part of the high-temperature superconducting coil where strength is required.

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