Bundled superconducting wire and superconducting coil

Abstract

To suppress the positional deviation in a tape width direction between a plurality of superconducting wires constituting a bundled superconducting wire that has good thermal conductivity and is resistant to deterioration of a superconducting layer.SOLUTION: A bundled superconducting wire 1 includes an oxide superconducting layer 25 stacked together with other layers on a metal substrate 22, and is provided with a plurality of superconducting wires 20 in a tape shape and bundled together with tape surfaces 60 facing each other, an insulating material layer 41 that integrally covers the periphery of the plurality of superconducting wires 20 and has insulating properties, and an adhesive layer 42 that is provided at least in a portion between the opposing tape surfaces 60 of the plurality of superconducting wires 20 and has adhesive properties.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] An embodiment of the present invention relates to a bundle-type superconducting wire and a superconducting coil. [Background technology]

[0002] In recent years, there has been active research into superconducting coils using high-temperature superconducting wires, such as REBCO wires using (RE)Ba2Cu3O7 containing rare earths (RE). In particular, high-temperature superconducting wires, which are manufactured by forming multiple types of layers on a substrate with a thickness of about 50 to 100 μm, have the characteristic of having a large current capacity under high magnetic fields, and it is expected that they will be used to create superconducting coils that generate high magnetic fields. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5395870 [Patent Document 2] Patent No. 6505565 [Patent Document 3] JP 2018-26233 A [Patent Document 4] Patent Publication No. 2021-15729 [Patent Document 5] Patent No. 5558794 Summary of the Invention [Problem to be solved by the invention]

[0004] Superconducting coils obtained by winding high-temperature superconducting wire and impregnating it with resin have the problem that a peeling force acts on the superconducting layer inside the high-temperature superconducting wire due to the difference in thermal contraction rate between the impregnating resin and the high-temperature superconducting wire, which can cause delamination and deterioration of the superconducting properties. Known techniques for avoiding this delamination include manufacturing the superconducting coil without impregnation (without resin impregnation) and separating the coil turns. However, manufacturing a superconducting coil without impregnation has the disadvantage of reducing mechanical strength.

[0005] As a technique for separating coil turns, a technique for winding a superconducting wire and a release tape together is known. However, this technique has a problem that the outer diameter of the superconducting coil increases by the thickness of the release tape, and the current density of the superconducting coil decreases. Attempts have also been made to reduce the thickness of the release tape, but thin release tapes are difficult to handle and easily break or deform. For this reason, there is a limit to the improvement of the current density by thinning the release tape. For these reasons, there is a demand for avoiding deterioration due to delamination of the superconducting wire without separating the coil turns.

[0006] As a technique for giving the superconducting wire itself a mold-releasing effect, a technique is known in which the ends of the superconducting wire in the width direction are joined together in a structure in which two superconducting wires are stacked (bundled) (so-called bundle structure), creating a cavity near the center of the superconducting wire in the width direction. However, with this technique, it is difficult to stably form the joint portion of the ends of the superconducting wire in the width direction in the longitudinal direction. In reality, there is a problem that gaps are formed between the superconducting wires in the longitudinal direction, and the impregnated resin gets into these gaps and deteriorates them. In addition, although this technique does not require a mold-releasing tape, it does require an insulating material between the turns, and there is a problem that the current density decreases when the insulating material is wound together.

[0007] In addition, a technique is known in which the ends of the superconducting wire in the width direction are connected with a metal member and a non-adhesive layer is provided on the tape surface, but this technique has a problem in that the current density decreases due to the addition of the metal member.

[0008] Also, a technique is known in which a bonding material made of tin is filled between two superconducting wires. With this technique, the impregnating resin does not get between the superconducting wires, but the two superconducting wires are firmly fixed to each other by the tin, so there is a problem that no release action is obtained and it is difficult to avoid deterioration due to delamination of the superconducting wires. Also, a technique is known in which a release material is applied around the superconducting wires. However, with this technique, there is a problem that when an impregnated coil is manufactured, the superconducting wires are released from the surrounding impregnating resin layer, which inhibits heat conduction.

[0009] A similar concept is used to bundle multiple superconducting wires, and a technique is known in which multiple superconducting wires are bundled and wrapped with insulating tape, with a release material provided between the superconducting wires. This technique has the problem that when a resin-impregnated coil is produced, the impregnating resin seeps through the gaps between the insulating tapes and gets between the superconducting wires, and may mix with or replace the release material, thereby hindering the release action. In addition, since the superconducting wires are bundled without being bonded to each other, there is the problem that the bundled superconducting wires may be misaligned in the tape width direction.

[0010] An embodiment of the present invention has been made taking into consideration the above circumstances, and aims to provide a bundle-type superconducting wire that has good thermal conductivity and is less susceptible to deterioration of the superconducting layer, and to suppress misalignment in the tape width direction between the multiple superconducting wires that make up the bundle-type superconducting wire. [Means for solving the problem]

[0011] A bundle-type superconducting wire according to an embodiment of the present invention has an oxide superconducting layer stacked together with other layers on a metal substrate, and is tape-shaped and includes a plurality of superconducting wires bundled together with their tape surfaces facing each other, an insulating layer integrally covering the periphery of the plurality of superconducting wires and having insulating properties, and an adhesive layer having adhesive properties and provided in at least a portion between the opposing tape surfaces of the plurality of superconducting wires. Effect of the Invention

[0012] According to an embodiment of the present invention, a bundle-type superconducting wire having good thermal conductivity and in which deterioration of the superconducting layer is unlikely to occur can be obtained, and misalignment in the tape width direction between the multiple superconducting wires that make up the bundle-type superconducting wire can be suppressed. [Brief description of the drawings]

[0013] [Figure 1] FIG. 2 is a cross-sectional view showing the bundle-type superconducting wire of the first embodiment. [Diagram 2] FIG. [Diagram 3] FIG. 2 is a perspective view showing the configuration of a superconducting coil. [Figure 4] FIG. 6 is a cross-sectional view showing a bundle-type superconducting wire according to a second embodiment. [Diagram 5] FIG. 11 is a cross-sectional view showing a bundle-type superconducting wire according to a third embodiment. [Figure 6] FIG. 11 is a cross-sectional view showing a bundle-type superconducting wire according to a fourth embodiment. [Figure 7] FIG. 13 is a cross-sectional view showing a bundle-type superconducting wire according to a fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] (First embodiment) Hereinafter, embodiments of the bundle-type superconducting wire and the superconducting coil will be described in detail with reference to the drawings. First, a first embodiment will be described with reference to Figs.

[0015] Reference numeral 1 in Fig. 1 denotes a bundle-type superconducting wire according to a first embodiment. This bundle-type superconducting wire 1 is used in superconducting devices such as a superconducting coil 10 (Fig. 3). For example, the bundle-type superconducting wire 1 is wound to produce the superconducting coil 10.

[0016] One bundled superconducting wire 1 is formed by bundling a plurality of superconducting wires 20. In the example of Fig. 1, two superconducting wires 20 made of laminated thin layers and formed into a tape shape are laminated and bundled together with their tape surfaces (wide surfaces) facing each other.

[0017] First, the configuration of the superconducting wire 20 will be described with reference to FIG. 2. The superconducting wire 20 is generally in the form of a tape in which a plurality of thin-film layers are laminated. The superconducting wire 20 is, for example, an REBCO wire including a superconducting layer 25 made of a rare metal oxide (RE oxide). Such a wire is also called a high-temperature superconducting wire or an oxide superconducting wire. The superconducting layer 25 is also called a high-temperature superconducting layer or an oxide superconducting layer.

[0018] Superconducting wire 20 includes stabilization layer 21, substrate 22, orientation layer 23, intermediate layer 24, superconducting layer 25, and protective layer 26. However, the types and numbers of layers constituting superconducting wire 20 are not limited to those described above, and may be more or less as needed.

[0019] Stabilization layer 21 is a layer that covers the entire surface of superconducting wire 20. Stabilization layer 21 is made of a highly conductive metal such as copper or aluminum. Stabilization layer 21 serves as a path for bypassing excess current flowing through superconducting layer 25, thereby preventing thermal runaway.

[0020] The substrate 22 is formed of a high-strength metal material such as a nickel-based alloy, stainless steel, or copper. The orientation layer 23 is formed on the substrate 22. The orientation layer 23 is formed of a metal material such as magnesium that orients the intermediate layer 24 on the surface of the substrate 22. The intermediate layer 24 is formed on the orientation layer 23. The intermediate layer 24 prevents thermal distortion caused by thermal contraction of the substrate 22 and the superconducting layer 25.

[0021] Superconducting layer 25 is formed on intermediate layer 24. Superconducting layer 25 is made of rare metal oxide (RE oxide). Protective layer 26 is formed on superconducting layer 25. Protective layer 26 is made of a metal material such as silver, gold, or platinum. Protective layer 26 prevents oxygen contained in superconducting layer 25 from diffusing from superconducting layer 25, and protects superconducting layer 25.

[0022] The substrate 22, the orientation layer 23, the intermediate layer 24, the superconducting layer 25, and the protective layer 26 constitute a superconducting laminate 27. A single superconducting wire 20 is a wire in which the periphery of the superconducting laminate 27 is covered with a stabilizing layer 21.

[0023] Here, of the four faces parallel to the longitudinal direction of one superconducting wire 20, two wide faces (tape faces) are called main faces 60. Of the two main faces 60 of superconducting wire 20, the main face 60 closer to superconducting layer 25 is called proximal face 60A, and the other main face 60 farther away is called distal face 60B.

[0024] FIG. 1 shows a cross section of a bundle-type superconducting wire 1 of the first embodiment cut along a plane perpendicular to the longitudinal direction.

[0025] In the bundle-type superconducting wire 1, a plurality of superconducting wires 20 are stacked so that their tape surfaces face each other. Furthermore, an insulating layer 41 is disposed on the outer periphery of the stacked plurality of superconducting wires 20.

[0026] Although the number n of superconducting wires 20 included in one bundle-type superconducting wire 1 is set to "2", n may be 3 or more.

[0027] The insulating material layer 41 integrally covers the periphery of the multiple (two) superconducting wires 20. For example, the insulating material layer 41 is coated over the entire outer surface of the multiple superconducting wires 20. The insulating material layer 41 has insulating properties, insulates the multiple superconducting wires 20 from the surroundings, and functions as a cooling path that transfers heat generated in the superconducting wires 20 to the surroundings. The insulating material layer 41 also has a function of preventing the impregnating resin from entering the gaps between the multiple superconducting wires 20 when a resin-impregnated coil is manufactured using the superconducting wires 20.

[0028] The insulating material (resin) constituting insulating layer 41 is preferably a material having good adhesion to superconducting wire 20. Insulating layer 41 is made of at least one material selected from the group consisting of epoxy resin, phenol resin, urea resin, melamine resin, polyimide, polyamide, polyamideimide, polyurethane, polyester, polyvinyl butyral, and polyvinyl formal. Methods for forming insulating layer 41 include spray painting, electrodeposition painting, and electrostatic painting.

[0029] Gaps 45 are formed between the opposing tape surfaces of the multiple superconducting wires 20. No insulating material layer 41 is disposed in the gaps 45. An adhesive layer 42 having adhesive properties is disposed in at least a partial region of the gaps 45.

[0030] In the first embodiment, the entire area of ​​the gap 45 is filled with the adhesive layer 42. The adhesive layer 42 is arranged for the purpose of preventing the multiple superconducting wires 20 from being misaligned with each other in the tape width direction (the left-right direction on the paper surface of FIG. 1).

[0031] The adhesive layer 42 is made of a resin different from that of the insulating material layer 41. The material constituting the adhesive layer 42 preferably has high adhesive strength at the application temperature when the insulating material layer 41 is formed and at the curing temperature of the insulating material layer 41. In addition, a material having a glass transition temperature lower than these temperatures is preferably used for the adhesive layer 42. For example, the adhesive layer 42 is made of at least one material selected from the group consisting of an acrylic adhesive, a urethane adhesive, a silicone adhesive, and a rubber adhesive.

[0032] Generally, the glass transition temperature (Tg) of an acrylic adhesive is about -60°C to -40°C. The glass transition temperature of a urethane adhesive is about -40°C to +50°C. The glass transition temperature of a silicone adhesive is about -130°C to -110°C. The glass transition temperature of a rubber adhesive is about -40°C to +50°C.

[0033] It is desirable that the adhesive strength of adhesive layer 42 becomes small at or below the curing temperature of insulating material layer 41. For example, when adhesive layer 42 becomes at or below its glass transition temperature, it is desirable that the adhesive strength per unit area between adhesive layer 42 and superconducting wire 20 becomes smaller than the adhesive strength per unit area between insulating material layer 41 and superconducting wire 20. Furthermore, it is desirable that this adhesive strength becomes smaller than the allowable peel strength per unit area of ​​superconducting layer 25 when the temperature becomes at or below the glass transition temperature.

[0034] In this way, after the insulating material layer 41 is cured, the adhesive strength of the adhesive layer 42 is weakened, and the adhesive layer 42 can function as a release layer. By causing peeling at the adhesive layer 42, it is possible to prevent unnecessary force from being applied to the superconducting layer 25 and suppress deterioration of the superconducting layer 25. On the other hand, before the insulating material layer 41 is cured, the adhesive strength of the adhesive layer 42 is maintained, and it is possible to prevent the multiple superconducting wires 20 from being misaligned with each other in the tape width direction.

[0035] The allowable peeling force of superconducting layer 25 refers to the maximum force (allowable force) among unnecessary forces applied to superconducting layer 25 that can maintain a state in which superconducting layer 25 does not peel off.

[0036] When the number n of superconducting wires 20 is set to "3" or more, two or more gaps 45 are generated. It is desirable that adhesive layer 42 is provided in all of gaps 45, but a certain effect can be achieved if adhesive layer 42 is provided in at least one of the gaps.

[0037] The operation of the first embodiment will be specifically described. For example, a case can be considered in which a room temperature curable epoxy resin is applied as the insulating layer 41 to the bundled superconducting wires 20, an acrylic adhesive is used as the adhesive layer 42, and the epoxy resin is cured by leaving it at room temperature for 50 hours. In this case, since the glass transition temperature of the acrylic resin is lower than the curing temperature of the epoxy resin, the acrylic adhesive (adhesive layer 42) can firmly bond the superconducting wires 20 together under the curing condition of the epoxy resin. This can prevent the multiple superconducting wires 20 from being displaced from each other in the tape width direction due to an external force F based on factors such as vibration of the manufacturing device and handling by an operator.

[0038] In addition, by preventing such misalignment, it is possible to prevent an increase in the width of the bundled superconducting wire 1, which occurs when the insulating layer 41 is hardened in a state in which the multiple superconducting wires 20 are misaligned with each other in the tape width direction. Furthermore, when the bundled superconducting wire 1 with an unnecessary increase in width is coiled, it is possible to prevent an unnecessary decrease in the current density of the entire coil.

[0039] Moreover, when the adhesive layer 42 is cooled to a temperature below the glass transition temperature, it changes from a rubbery state to a glassy state, and its hardness increases, thereby decreasing its adhesive strength. Thus, when the adhesive layer 42 exceeds the glass transition temperature, it has the function of bonding and bundling the superconducting wires 20 together, and when it is cooled to a temperature below the glass transition temperature, it loses its adhesive strength and functions as a release layer that separates the superconducting wires 20 from each other.

[0040] When a polyimide resin that cures at a temperature higher than room temperature, for example, at 150° C. for 12 hours, is used as insulating material layer 41, a urethane-based adhesive having a glass transition temperature of about 50° C. may be used as adhesive layer 42. Even in this case, since the glass transition temperature of adhesive layer 42 is lower than the curing temperature of insulating material layer 41, superconducting wires 20 can be adhered to each other when insulating material layer 41 is cured, thereby preventing misalignment. Then, adhesive layer 42 loses its adhesive force when cooled to a temperature equal to or lower than the glass transition temperature, and functions as a release layer that peels superconducting wires 20 from each other.

[0041] When the bundled superconducting wire 1 of the first embodiment is cooled to 77K or below, or when electricity is applied in the cooled state, an external force F may be applied to the superconducting layer 25 in the peeling direction (the vertical direction in the plane of FIG. 1) due to electromagnetic stress or thermal stress. In this case, if the adhesive strength between the adhesive layer 42 and the superconducting wire 20 is smaller than the allowable peeling force of the superconducting layer 25, the adhesive layer 42 will be peeled off from the superconducting wire 20 before the superconducting layer 25 is peeled off. This makes it possible to prevent the superconducting layer 25 from being destroyed.

[0042] Similarly, at a temperature of 77 K or less, stress in the peeling direction may be applied to interface 48 between insulating layer 41 and the tape surface of superconducting wire 20. Even in this case, if the adhesive strength between adhesive layer 42 and superconducting wire 20 is smaller than the adhesive strength between insulating layer 41 and superconducting wire 20, adhesive layer 42 will be peeled off from superconducting wire 20 before insulating layer 41 is peeled off from interface 48 between insulating layer 41 and the tape surface of superconducting wire 20. As a result, the adhesive state between insulating layer 41 and superconducting wire 20 is maintained, so that heat conduction between insulating layer 41 and superconducting wire 20 is not hindered and insulating layer 41 effectively functions as a cooling path.

[0043] When the number n of superconducting wires 20 is "3" or more, two or more gaps 45 are generated. It is sufficient that adhesive layer 42 is provided in at least one of these gaps 45. In this way, when an external force F is applied to bundle-type superconducting wire 1, peeling occurs at adhesive layer 42, and peeling inside superconducting layer 25 or peeling at interface 48 between superconducting layer 25 and insulating layer 41 can be prevented.

[0044] Therefore, when the superconducting coil 10 is manufactured by winding the wire, the bundle-type superconducting wire 1 can be obtained which is reliably insulated from the surroundings, has good thermal conductivity, and is less susceptible to deterioration of the superconducting layer 25.

[0045] As shown in FIG. 3, when a superconducting coil 10 is manufactured, a pancake-shaped winding portion 12 having a space penetrating the center of the winding axis is formed by winding a bundle-type superconducting wire 1 around a winding drum 13.

[0046] Here, the superconducting coil 10 in which the bundle-type superconducting wire 1 is wound concentrically to form a pancake shape is called a pancake coil.

[0047] The superconducting coil 10 is impregnated with an adhesive insulating material such as epoxy resin. By impregnating with the adhesive resin, adjacent bundle-type superconducting wires 1 inside the superconducting coil 10 are fixed to each other, and the thermal conductivity and mechanical strength of the superconducting coil 10 are improved.

[0048] An insulating sheet 16 is provided on the side surfaces (top and bottom surfaces) of the winding portion 12. This insulating sheet 16 insulates the winding portion 12 from the adjacent superconducting coils 10. Epoxy resin or fiber-reinforced plastic is preferably used as the insulating sheet 16. Furthermore, an insulating material having adhesive properties, such as epoxy resin, can be filled between the winding portion 12 and the insulating sheet 16 to form an insulating resin layer 18.

[0049] By manufacturing the superconducting coil 10 using the bundle-type superconducting wire 1 of the first embodiment, it is possible to obtain the superconducting coil 10 having good thermal conductivity and in which the superconducting layer 25 is less likely to deteriorate.

[0050] Second embodiment Next, a second embodiment will be described with reference to Fig. 4. Note that the same components as those shown in the above-mentioned embodiment are denoted by the same reference numerals and the duplicated description will be omitted.

[0051] In the second embodiment, adhesive layer 42 fills only a portion of gap 45, and the remaining portion is hollow 46. That is, adhesive layer 42 is provided in gap 45 between a plurality of superconducting wires 20 at least at both ends in the tape width direction of superconducting wire 20, and a region (hollow 46) where adhesive layer 42 is not provided is present in the center in the tape width direction.

[0052] In this way, even if a force in the peeling direction is applied to superconducting wire 20 from the outside, the force acts to pull adhesive layer 42 via stabilization layer 21. For example, superconducting wire 20 as a whole is deformed in the portion of cavity 46 so that the dimension of superconducting wire 20 in the thickness direction becomes larger. However, the presence of cavity 46 has the effect of making it difficult to generate a force that peels superconducting layer 25 from other layers or peels insulating layer 41 from interface 48 between superconducting wire 20 and the tape surface.

[0053] Third embodiment Next, a third embodiment will be described with reference to Fig. 5. Note that the same components as those shown in the above-described embodiment are denoted by the same reference numerals and will not be described again.

[0054] In the superconducting wire 20A of the third embodiment, the periphery of the superconducting laminate 27 is covered with a stabilizing layer 21. It is preferable that the stabilizing layer 21 is formed to a uniform thickness around the superconducting laminate 27. However, depending on the manufacturing method, the thickness of the stabilizing layer 21 near the end portion in the tape width direction of the superconducting wire 20A becomes several μm to several tens of μm larger than the thickness of the stabilizing layer 21 near the center portion in the tape width direction. Such a cross-sectional shape of the stabilizing layer 21 is also called a dog-bone shape. As a result, the thickness (dimension in the direction perpendicular to the tape surface) of the superconducting wire 20A becomes larger near the end portion than near the center portion in the tape width direction.

[0055] In the third embodiment, the ends of each superconducting wire 20 are thicker than the central portion in the tape width direction, so that bulges 49 are formed at the ends of the superconducting wire 20A in the tape width direction. The superconducting wires 20A are in direct contact with each other at the bulges 49. That is, at least a portion of the ends of the multiple superconducting wires 20 in the tape width direction are in direct contact with each other. In this way, a current flows through the contacting portion, so that a bypass current can flow.

[0056] For example, when the superconducting wires 20 are in direct contact with each other, a current can be passed between the superconducting wires 20A, 20A. As a result, even if one of the superconducting wires 20A has a locally low critical current value in a portion of its longitudinal direction and the current flow value is about to exceed the critical current value in that portion, the current is diverted to the other superconducting wire 20B. As a result, the portion of one of the superconducting wires 20A with a low critical current value (portion with reduced performance) can be prevented from changing into a normal conductor, and thermal runaway is less likely to occur in the superconducting wire 20.

[0057] (Fourth embodiment) Next, a fourth embodiment will be described with reference to Fig. 6. Note that the same components as those shown in the above-mentioned embodiments are given the same reference numerals and the duplicated description will be omitted.

[0058] Of the tape surfaces that are the two main surfaces 60 (FIG. 2) of the superconducting wire 20, the tape surface located relatively closer to the superconducting layer 25 (FIG. 2) is defined as the proximal surface 60A, and the tape surface located relatively farther from the superconducting layer 25 is defined as the distal surface 60B. In other words, when comparing the distances from each tape surface to the substrate 22 and the superconducting layer 25, the tape surface located closer to the superconducting layer 25 than the substrate 22 is defined as the proximal surface 60A. Furthermore, the tape surface located farther from the superconducting layer 25 than the substrate 22 is defined as the distal surface 60B. In this case, the multiple superconducting wires 20, 20 are arranged such that the proximal surface 60A and the distal surface 60B face each other.

[0059] That is, when a plurality of superconducting wires 20, 20 are overlapped, the superconducting wires 20, 20 are oriented such that the proximal surface 60A of one superconducting wire 20 faces (is close to) the distal surface 60B of the other superconducting wire 20. In this manner, the distal surfaces 60B of the one and the other superconducting wires 20, 20 face the same direction.

[0060] Assume that a superconducting coil 10 (FIG. 3) is manufactured using the bundle-type superconducting wire 1. It is assumed that a current is applied to such superconducting coil 10 in a self-magnetic field generated by the superconducting coil 10 itself, or in an external magnetic field in which the component in the coil axial direction perpendicular to the coil circumferential direction is in the same direction as the self-magnetic field.

[0061] In this case, an electromagnetic force proportional to the magnetic field and current acts on the bundle-type superconducting wire 1 of each turn in the superconducting coil 10. The bundle-type superconducting wire 1 receives a force that spreads in the coil radial direction due to the coil radial component of the electromagnetic force. From a microscopic point of view, it is the superconducting layer 25 in the bundle-type superconducting wire 1 that receives this electromagnetic force.

[0062] In the fourth embodiment, one superconducting wire 20 is wound with the proximal surface 60A on the inner circumferential side and the distal surface 60B on the outer circumferential side. That is, the distal surfaces 60B of each of the superconducting wires 20, 20 are wound facing the same direction. As a result, for each of the superconducting wires 20, the substrate 22 having high strength is disposed on the outer circumferential side (outer diameter side) of the superconducting layer 25. This makes it possible to achieve a structure in which the superconducting layer 25 is less likely to be destroyed by electromagnetic force.

[0063] Fifth embodiment Next, a fifth embodiment will be described with reference to Fig. 7. Note that the same components as those shown in the above-mentioned embodiments are given the same reference numerals and the duplicated description will be omitted.

[0064] Of the two main surfaces 60 (FIG. 2) of the superconducting wire 20, that is, the tape surfaces, the one located relatively closer to the superconducting layer 25 (FIG. 2) is defined as the proximal surface 60A, and the one located relatively farther from the superconducting layer 25 is defined as the distal surface 60B. In other words, when comparing the distances from each tape surface to the substrate 22 and the superconducting layer 25, the tape surface located closer to the superconducting layer 25 than the substrate 22 is defined as the proximal surface 60A. Furthermore, the tape surface located farther from the superconducting layer 25 than the substrate 22 is defined as the distal surface 60B. In this case, the superconducting wire 20 located on the outermost side in the stacking direction among the plurality of superconducting wires 20 is disposed so that the proximal surface 60A faces the other superconducting wires 20 and the distal surface 60B faces outward. In the example of FIG. 7, two superconducting wires 20, 20 are arranged so that proximal surfaces 60A, 60A face each other.

[0065] That is, when the superconducting wires 20, 20 are overlapped, the superconducting wires 20, 20 are oriented such that the distal surfaces 60B, 60B of the superconducting wires 20, 20 are disposed on the outer surface side of the bundle-type superconducting wire 1. In this manner, in one superconducting wire 20, the high-strength substrates 22 provided on both the first and second superconducting wires 20, 20 are disposed on the outer surface side of the bundle-type superconducting wire 1. For example, even if a worker inadvertently scratches the surface of one superconducting wire 20 while carrying the superconducting wire 20, the high-strength substrate 22 is disposed on the outer surface side, so that the possibility of the superconducting layer 25 inside the substrate 22 being damaged can be reduced.

[0066] In addition, when three or more odd-numbered superconducting wires 20 are stacked, there are two superconducting wires 20 in which only one of the two main surfaces 60 is adjacent to another superconducting wire 20, that is, there are two superconducting wires 20 arranged at the ends in the direction in which the superconducting wires 20 are stacked. In other words, there are two superconducting wires 20 arranged at the outermost positions in the direction in which the superconducting wires 20 are stacked. These two superconducting wires 20 are arranged such that the surface facing the other superconducting wire 20 is the proximal surface 60A and the other surface is the distal surface 60B. In this way, the same effect as that described above can be obtained.

[0067] When an even number of superconducting wires 20, 4 or more, are stacked, it is preferable that the proximal surfaces 60A, 60A of the superconducting wires 20 arranged at the ends in the stacking direction of the superconducting wires 20 face each other between adjacent superconducting wires 20. When the proximal surfaces 60A of adjacent superconducting wires 20 face each other, a bypass current flows more easily, and therefore the thermal runaway as described in the third embodiment can be suppressed.

[0068] The present invention has been described above based on the first to fifth embodiments, but the configuration applied in any of the embodiments may be applied to other embodiments, and the configurations applied in each embodiment may be combined.

[0069] In the above-described embodiment, the superconducting coil 10 is illustrated as having a circular coil shape. However, the winding section 12 to which the above-described embodiment can be applied is not limited to a circular pancake coil. For example, the above-described embodiment can also be applied to coils having non-circular shapes such as a saddle shape or an elliptical shape.

[0070] According to at least one of the embodiments described above, the bundled superconducting wire 1 includes the adhesive layer 42 having adhesiveness, which is provided at least in a part between the opposing tape surfaces of the plurality of superconducting wires 20. This makes it possible to provide the bundled superconducting wire 1 having good thermal conductivity and in which the superconducting layer 25 is less likely to deteriorate, and also makes it possible to suppress misalignment in the tape width direction between the plurality of superconducting wires 20 constituting the bundled superconducting wire 1.

[0071] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, modifications, and combinations can be made without departing from the spirit of the invention. These embodiments or modifications thereof are within the scope of the invention and its equivalents as described in the claims, as well as within the scope and spirit of the invention. [Explanation of symbols]

[0072] 1...bundle-type superconducting wire, 10...superconducting coil, 12...winding portion, 13...winding drum, 16...insulating sheet, 18...insulating resin layer, 20, 20A...superconducting wire, 21...stabilization layer, 22...substrate, 23...orientation layer, 24...intermediate layer, 25...superconducting layer, 26...protective layer, 27...superconducting laminate, 41...insulating layer, 42...adhesive layer, 45...gap, 46...cavity, 48...interface, 49...bulge, 60...main surface, 60A...proximal surface, 60B...distal surface, F...external force.

Claims

1. a plurality of superconducting wires each having an oxide superconducting layer laminated on a metal substrate together with other layers, each of which is in the form of a tape and bound together so that the tape surfaces face each other; an insulating layer integrally covering the periphery of the plurality of superconducting wires and having insulating properties; an adhesive layer having adhesiveness, the adhesive layer being provided on at least a portion between the tape surfaces of the plurality of superconducting wires facing each other; Equipped with Bundle-type superconducting wire.

2. the insulating layer is made of at least one material selected from the group consisting of epoxy resin, phenolic resin, urea resin, melamine resin, polyimide, polyamide, polyamideimide, polyurethane, polyester, polyvinyl butyral, and polyvinyl formal; The pressure-sensitive adhesive layer is made of at least one material selected from the group consisting of an acrylic pressure-sensitive adhesive, a urethane pressure-sensitive adhesive, a silicone pressure-sensitive adhesive, and a rubber pressure-sensitive adhesive.

2. The bundle-type superconducting wire according to claim 1.

3. an adhesive strength per unit area between the adhesive layer and the superconducting wire becomes smaller than an adhesive strength per unit area between the insulating layer and the superconducting wire and smaller than an allowable peel strength per unit area of ​​the superconducting layer when the adhesive layer is at or below a glass transition temperature.

3. The bundle-type superconducting wire according to claim 1 or 2.

4. the adhesive layer is provided at least at both ends of the superconducting wire in a tape width direction among the gaps between the plurality of superconducting wires, and a region in which the adhesive layer is not provided is present in a central portion in the tape width direction.

3. The bundle-type superconducting wire according to claim 1 or 2.

5. The superconducting wire has an end portion that is thicker than a central portion in a width direction of the tape, At least a part of the ends of the plurality of superconducting wires in the tape width direction is in direct contact with each other.

3. The bundle-type superconducting wire according to claim 1 or 2.

6. When comparing the distances from each of the two tape surfaces of the superconducting wire to the substrate and the superconducting layer, the tape surface located closer to the superconducting layer than the substrate is defined as a proximal surface, and the tape surface located farther from the superconducting layer than the substrate is defined as a distal surface, The plurality of superconducting wires are arranged such that the proximal surface and the distal surface face each other.

3. The bundle-type superconducting wire according to claim 1 or 2.

7. When comparing the distances from each of the two tape surfaces of the superconducting wire to the substrate and the superconducting layer, the tape surface located closer to the superconducting layer than the substrate is defined as a proximal surface, and the tape surface located farther from the superconducting layer than the substrate is defined as a distal surface, Among the plurality of superconducting wires, the superconducting wire disposed on the outermost side in the stacking direction is disposed such that the proximal surface faces the other superconducting wires and the distal surface faces outward.

3. The bundle-type superconducting wire according to claim 1 or 2.

8. A coil formed by winding the bundle-type superconducting wire according to claim 1 or 2. Superconducting coil.

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