Repairing method for self-fused superconducting wire for superconducting coil, self-fused superconducting wire for superconducting coil, and superconducting coil

Abstract

To provide a method for repairing a self-fused superconducting wire for a superconducting coil, a self-fused superconducting wire for a superconducting coil, and a superconducting coil capable of imparting sufficient insulation performance and self-fusion performance to the self-fused superconducting wire for a superconducting coil after repair without cutting and removing a defective portion of the self-fused superconducting wire for a superconducting coil.SOLUTION: In a repairing method of a self-fused superconducting wire for a superconducting coil, an insulating fusion tape is attached to a self-fused layer of the self-fused superconducting wire for the superconducting coil by an adhesive tape layer. The insulating fusion tape has an adhesive tape layer, an insulating tape layer covering one main surface of the adhesive tape layer, and a self-fusion tape layer covering one main surface of the insulating tape layer, so as to cover a defective portion existing from the insulating layer to a front surface of the self-fusion layer in the self-fusion superconducting wire for the superconducting coil comprising a superconducting wire, an insulating layer covering an outer peripheral surface of the superconducting wire and containing enamel, and the self-fusion layer covering an outer peripheral surface of the insulating layer.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a repair method for a self-bonding superconducting wire for a superconducting coil, a self-bonding superconducting wire for a superconducting coil, and a superconducting coil. [Background technology]

[0002] Self-bonding superconducting wire for superconducting coils exhibits superconducting performance at extremely low temperatures. A superconducting coil is obtained by winding such self-bonding superconducting wire for superconducting coils around a bobbin. Self-bonding superconducting wire for superconducting coils has the advantage of being able to carry an extremely large current compared to ordinary electric wires such as copper wires.

[0003] For example, Patent Document 1 describes a superconducting magnet device that has a first layer formed by solenoidally winding superconducting wire, a second layer formed by solenoidally winding superconducting wire coaxially with the first layer and on the outer diameter side, and a first heat transfer member that is liquid-permeable and is arranged between the first and second layers, in order to obtain a self-fused formed coil that improves thermal conductivity while maintaining adhesive strength inside the coil winding.The first layer, second layer, and first heat transfer member are fixed by a thermoplastic resin that has passed through the first heat transfer member and hardened.

[0004] Incidentally, self-bonding superconducting wires may have localized defects (insulation defects) in the insulating layer or self-bonding layer. When a self-bonding superconducting wire having such localized defects is wound into a coil, there is a concern that the insulation and bonding properties may be reduced at the defective parts. Furthermore, when a superconducting coil is fabricated using a self-bonding superconducting wire having such defective parts, the possibility of quenching increases. Defective parts include, for example, pinholes in the insulating layer that occur when the insulating layer is formed by baking enamel varnish, and foreign matter that occurs due to remaining solvent in the enamel varnish.

[0005] Conventionally, when repairing a defective portion of a self-bonding superconducting wire, the defective portion has been cut and removed, which has resulted in the inability to obtain a self-bonding superconducting wire having a predetermined length sufficient for manufacturing an impregnation-less type superconducting coil, and in the need to join self-bonding superconducting wires that are shorter than the predetermined length together, thereby providing multiple joints between the self-bonding superconducting wires in the superconducting coil.

[0006] Furthermore, since superconducting coils obtained by winding superconducting wires that do not have a self-fusing layer are impregnated, with such types of superconducting wires, defective areas can be repaired by applying insulating resin to the localized defective areas or covering them with adhesive insulating tape. However, with self-fusing superconducting wires, it is difficult to locally apply both the insulating resin for forming the insulating layer and the self-fusing resin for forming the self-fusing layer to the defective areas, and furthermore, adhesive insulating tape cannot ensure the necessary and sufficient fusing force for the defective areas in impregnation-less superconducting coils. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2017-42246 Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present disclosure is to provide a repair method for self-fusing superconducting wire for superconducting coils, which can impart sufficient insulating performance and self-fusing performance to the repaired self-fusing superconducting wire for superconducting coils without cutting and removing defective parts of the self-fusing superconducting wire for superconducting coils, a self-fusing superconducting wire for superconducting coils, and a superconducting coil. [Means for solving the problem]

[0009] [1] A repair method for self-fusing superconducting wire for a superconducting coil, the self-fusing superconducting wire for a superconducting coil comprising a superconducting wire, an insulating layer containing enamel covering the outer peripheral surface of the superconducting wire, and a self-fusing layer covering the outer peripheral surface of the insulating layer, the method comprising: attaching an insulating fusion tape comprising an adhesive tape layer, an insulating tape layer covering one main surface of the adhesive tape layer, and a self-fusing tape layer covering one main surface of the insulating tape layer to the self-fusing layer of the self-fusing superconducting wire for a superconducting coil using the adhesive tape layer, so as to cover a defective portion that exists from the insulating layer to the surface of the self-fusing layer. [2] The repair method for self-fusing superconducting wire for a superconducting coil according to [1] above, wherein the adhesive tape layer can be adhered to the self-fusing layer at room temperature. [3] The repair method for a self-fusing superconducting wire for a superconducting coil according to [1] or [2] above, wherein the adhesive tape layer is made of a silicone-based adhesive or an acrylic-based adhesive. [4] The method for repairing a self-fusing superconducting wire for a superconducting coil according to any one of [1] to [3] above, wherein the insulating tape layer is made of polyimide, polyester, fluororesin, or glass cloth. [5] The method for repairing a self-bonding superconducting wire for a superconducting coil according to any one of [1] to [4] above, wherein the self-bonding tape layer is made of a phenoxy resin. [6] A repair method for self-fusing superconducting wire for a superconducting coil according to any one of [1] to [5] above, wherein the size of the insulating fusion tape attached to the self-fusing superconducting wire for a superconducting coil along the longitudinal direction of the self-fusing superconducting wire for a superconducting coil is 2 mm or more and 20 mm or less. [7] The method for repairing a self-bonding superconducting wire for a superconducting coil according to any one of [1] to [6] above, wherein the insulating tape layer has a thickness of 10 μm or more and 50 μm or less. [8] The method for repairing a self-fusing superconducting wire for a superconducting coil according to any one of [1] to [7] above, wherein the thickness of the self-fusing tape layer is 10 μm or more and 50 μm or less. [9] A self-fusing superconducting wire for a superconducting coil, comprising: a superconducting wire; an insulating layer containing enamel covering the outer surface of the superconducting wire; a self-fusing layer covering the outer surface of the insulating layer; an adhesive tape layer; an insulating tape layer covering one main surface of the adhesive tape layer; and an insulating fusion tape that is attached by the adhesive tape layer so as to cover defective areas that extend from the insulating layer to the surface of the self-fusing layer.

[10] A superconducting coil comprising a reel and a self-fusing superconducting wire for a superconducting coil repaired by the repair method for self-fusing superconducting wire for a superconducting coil according to any one of [1] to [8] above or a fused product of self-fusing superconducting wire for a superconducting coil according to [9] above, wound spirally around the body of the reel. [Effects of the Invention]

[0010] According to the present disclosure, it is possible to provide a repair method for self-fusing superconducting wire for superconducting coils, which can impart sufficient insulating performance and self-fusing performance to the repaired self-fusing superconducting wire for superconducting coils without cutting and removing defective parts of the self-fusing superconducting wire for superconducting coils, a self-fusing superconducting wire for superconducting coils, and a superconducting coil. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a longitudinal sectional view showing an example of a self-fusion superconducting wire for a superconducting coil before being repaired by a method for repairing a self-fusion superconducting wire for a superconducting coil according to an embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing an example of a self-fusion superconducting wire for a superconducting coil before being repaired by a method for repairing a self-fusion superconducting wire for a superconducting coil according to an embodiment. [Figure 3] FIG. 3 is a perspective view showing an example of an insulating fusion tape used in the method for repairing a self-fusion superconducting wire for a superconducting coil according to the embodiment. [Figure 4] FIG. 4 is a vertical cross-sectional view showing an example of a self-fusion superconducting wire for a superconducting coil repaired by the method for repairing a self-fusion superconducting wire for a superconducting coil according to the embodiment. [Figure 5] FIG. 5 is a cross-sectional view showing an example of a self-fusion superconducting wire for a superconducting coil repaired by the method for repairing a self-fusion superconducting wire for a superconducting coil according to the embodiment. [Figure 6] FIG. 6 is a cross-sectional view showing another example of a self-fusion superconducting wire for a superconducting coil repaired by the method for repairing a self-fusion superconducting wire for a superconducting coil according to the embodiment. [Figure 7] FIG. 7 is an enlarged cross-sectional view of the superconducting coil of the embodiment, cut along a plane including the central axis of the barrel of the bobbin. DETAILED DESCRIPTION OF THE INVENTION

[0012] The embodiments will be described in detail below.

[0013] As a result of extensive research, the inventors have discovered that by applying a specified insulating fusion tape to a self-fusing superconducting wire for a superconducting coil having a defective portion, it is possible to impart sufficient insulating performance and self-fusing performance to the repaired self-fusing superconducting wire for a superconducting coil without cutting and removing the defective portion of the self-fusing superconducting wire for a superconducting coil, and have completed the present disclosure based on this finding.

[0014] First, a method for repairing a self-fusion superconducting wire for a superconducting coil according to an embodiment will be described.

[0015] In one embodiment, a method for repairing a self-fusing superconducting wire for a superconducting coil includes attaching an insulating fusion tape, which includes an adhesive tape layer, an insulating tape layer covering one main surface of the adhesive tape layer, and a self-fusing tape layer covering one main surface of the insulating tape layer, to the self-fusing layer of the self-fusing superconducting wire for a superconducting coil using the adhesive tape layer, so as to cover defective areas that exist from the insulating layer to the surface of the self-fusing layer in the self-fusing superconducting wire for a superconducting coil, which includes a superconducting wire, an insulating layer covering the outer surface of the superconducting wire and including enamel, and a self-fusing layer covering the outer surface of the insulating layer.

[0016] FIG. 1 is a longitudinal sectional view showing an example of a self-fusion superconducting wire for a superconducting coil before being repaired by a method for repairing a self-fusion superconducting wire for a superconducting coil according to an embodiment (hereinafter also simply referred to as a self-fusion superconducting wire). FIG. 2 is a transverse sectional view showing an example of a self-fusion superconducting wire for a superconducting coil before being repaired by a method for repairing a self-fusion superconducting wire for a superconducting coil according to an embodiment. FIG. 3 is a perspective view showing an example of an insulating fusion tape used in a method for repairing a self-fusion superconducting wire for a superconducting coil according to an embodiment. FIG. 4 is a longitudinal sectional view showing an example of a self-fusion superconducting wire for a superconducting coil repaired by a method for repairing a self-fusion superconducting wire for a superconducting coil according to an embodiment. FIG. 5 is a transverse sectional view showing an example of a self-fusion superconducting wire for a superconducting coil repaired by a method for repairing a self-fusion superconducting wire for a superconducting coil according to an embodiment.

[0017] 1 and 2, in the repair method for a self-bonding superconducting wire 1 according to the embodiment, a defective portion 14 present in the self-bonding superconducting wire 1 is repaired. The self-bonding superconducting wire 1 includes a superconducting wire 11, an insulating layer 12 containing enamel, and a self-bonding layer 13 having self-bonding properties.

[0018] The superconducting wire 11 constituting the self-fusion superconducting wire 1 is provided at the center of the self-fusion superconducting wire 1 and extends along the longitudinal direction of the self-fusion superconducting wire 1. The superconducting wire 11 has superconducting properties and is preferably made of Cu, a Cu alloy, Nb—Ti, or Nb3Sn.

[0019] The insulating layer 12 constituting the self-bonding superconducting wire 1 covers the entire outer periphery of the superconducting wire 11. The insulating layer 12 has electrical insulating properties and is made of formal, nylon, polyurethane, polyester, epoxy, polyimide, polyimide ester, polyamideimide, polyimidehydantoin, inorganic polymer, or an enamel of any of these with glass, polyester, Kevlar (registered trademark) (polyparaphenylene terephthalamide), alumina or other fibers wound around it and then treated with varnish, and is preferably made of formal, nylon 612, polyurethane, or polyamideimide.

[0020] The self-bonding layer 13 constituting the self-bonding superconducting wire 1 covers the entire outer periphery of the insulating layer 12. The self-bonding layer 13 has self-bonding properties and is made of phenoxy, epoxy, polyamide, polyester, polyimide, polyvinyl butyral, polyurethane, ethylene-methacrylic acid copolymer, hot melt adhesive, semi-cured epoxy resin, copolymer nylon, nylon, or the like.

[0021] Defective points 14 present in the self-fusion superconducting wire 1 are locally present from the insulating layer 12 to the surface of the self-fusion layer 13. Defective points 14 are, for example, pinholes that occur when forming the insulating layer 12, or foreign matter that occurs due to remaining solvent in the coating liquid used to form the insulating layer 12. For example, there are about five or fewer defective points 14 per 30 km of self-fusion superconducting wire.

[0022] Such a defective portion 14 is a portion that has a resistance of less than 5 MΩ when a voltage of 500 V is applied to the self-fusion superconducting wire 1. The presence of the defective portion 14 can be confirmed by bringing the self-fusion superconducting wire 1 before repair into contact with a voltage application brush, applying a voltage to the self-fusion superconducting wire 1, and measuring the resistance of a predetermined portion of the self-fusion superconducting wire 1.

[0023] As shown in Fig. 3, the insulating fusion tape 3 used in the method for repairing a self-fusing superconducting wire 1 includes an adhesive tape layer 31, an insulating tape layer 32, and a self-fusing tape layer 33. The adhesive tape layer 31 has adhesiveness to the self-fusing layer 13 of the self-fusing superconducting wire 1. The insulating tape layer 32 covers one main surface, for example, the entire main surface, of the adhesive tape layer 31. The self-fusing tape layer 33 has self-fusing properties and covers one main surface, for example, the entire main surface, of the insulating tape layer 32.

[0024] 4 and 5, in the method for repairing a self-bonding superconducting wire 1, an insulating fusion tape 3 is attached to the self-bonding layer 13 of the self-bonding superconducting wire 1 by an adhesive tape layer 31 so as to cover one defective portion 14 locally present in the self-bonding superconducting wire 1 from the outside of the self-bonding layer 13. For example, a worker manually attaches the insulating fusion tape 3 to the defective portion 14.

[0025] The insulating fusion tape 3 attached to the surface of the self-fusing layer 13 completely covers the defective portion 14. The adhesive tape layer 31 of the insulating fusion tape 3 is adhered to the self-fusing layer 13 of the self-fusing superconducting wire 1. The size in the width direction of the insulating fusion tape 3 is sufficiently larger than the defective portion 14.

[0026] Repair of the self-fusion superconducting wire 1 at the defective portion 14 is completed by attaching the insulating fusion tape 3 to the self-fusion layer 13 of the self-fusion superconducting wire 1 with the adhesive tape layer 31 so as to cover the defective portion 14. In the self-fusion superconducting wire 1 after repair of the defective portion 14, the defective portion 14 that is covered with the insulating fusion tape 3 and not exposed may remain empty as shown in Figures 4 to 5 and Figure 6 described later, or the resin that makes up the insulating tape layer 32 or the resin that makes up the self-fusion tape layer may flow into the empty space at the defective portion 14 by the fusion heat treatment during the manufacture of the superconducting coil, so that the defective portion 14 is filled with resin.

[0027] In this way, by repairing the self-bonding superconducting wire 1 by covering the defective portion 14 of the self-bonding superconducting wire 1 with the insulating fusion tape 3, it is possible to impart sufficient insulating performance and self-bonding performance to the repaired self-bonding superconducting wire 1 without cutting and removing the defective portion 14 of the self-bonding superconducting wire 1. In this way, since it is no longer necessary to cut and remove the defective portion of the self-bonding superconducting wire, which is performed in conventional repair methods, it is possible to easily manufacture a self-bonding superconducting wire 1 of the length required for manufacturing a superconducting coil, which has sufficient insulating performance and self-bonding performance without having a joint between the self-bonding superconducting wires. Furthermore, the occurrence of quenching is suppressed in a superconducting coil manufactured using the repaired self-bonding superconducting wire 1.

[0028] Furthermore, it is preferable that the adhesive tape layer 31 of the insulating fusion tape 3 is adhesive at room temperature to the self-fusion layer 13 of the self-fusion superconducting wire 1. If such an insulating fusion tape 3 is used, when the self-fusion superconducting wire 1 is wound at room temperature in the manufacture of a superconducting coil, the insulating fusion tape 3 is sufficiently adhered to the self-fusion layer 13 of the self-fusion superconducting wire 1, and therefore the insulating fusion tape 3 can be prevented from sliding on the surface of the self-fusion layer 13. Room temperature is 5°C or higher and 50°C or lower.

[0029] The adhesive tape layer 31 of the insulating fusion tape 3 is preferably a silicone-based adhesive or an acrylic-based adhesive. Such an adhesive tape layer 31 can be well bonded to the self-fusion layer 13 of the self-fusion superconducting wire 1 at temperatures ranging from extremely low temperatures to the fusion heat treatment temperature.

[0030] The insulating tape layer 32 of the insulating fusion tape 3 is preferably made of polyimide, polyester, fluororesin, or glass cloth. Such an insulating tape layer 32 can provide sufficient insulation to the repaired self-fusion superconducting wire 1 within a temperature range from extremely low temperatures to the fusion heat treatment temperature.

[0031] Furthermore, the self-adhesive tape layer 33 of the insulating fusion tape 3 is preferably made of a phenoxy resin. Such a self-adhesive tape layer 33 can impart sufficient self-adhesiveness to the repaired self-adhesive superconducting wire 1 within a temperature range from extremely low temperatures to the fusion heat treatment temperature.

[0032] Furthermore, the size of the insulating fusion tape 3 attached to the self-bonding superconducting wire 1 along the longitudinal direction of the self-bonding superconducting wire 1 (hereinafter simply referred to as the longitudinal direction) is set appropriately depending on the size of the defective portion 14. For example, the lower limit of the longitudinal size of the insulating fusion tape 3 is preferably 2 mm or more, more preferably 4 mm or more, and the upper limit is preferably 20 mm or less, more preferably 10 mm or less. When the size of the insulating fusion tape 3 is 2 mm or more, exposure of the defective portion 14 caused by the insulating fusion tape 3 sliding over the surface of the self-bonding layer 13 during, for example, a fusion heat treatment when manufacturing a superconducting coil can be sufficiently suppressed. When the size of the insulating fusion tape 3 is 20 mm or less, a sufficient number of turns required for coil design can be ensured.

[0033] Furthermore, the lower limit of the thickness of the adhesive tape layer 31 of the insulating fusion tape 3 is preferably 1 μm or more, and the upper limit is preferably 10 μm or less, more preferably 5 μm or less. When the thickness of the adhesive tape layer 31 is 1 μm or more, the adhesive tape layer 31 has sufficient adhesive strength to the self-fusion layer 13 of the self-fusion superconducting wire 1. When the thickness of the adhesive tape layer 31 is 10 μm or less, with respect to the gaps S (see FIG. 7 described later) between the self-fusion superconducting wires 1 in the superconducting coil obtained by winding the repaired self-fusion superconducting wire 1, it is possible to suppress an increase in the gaps S caused by attaching the insulating fusion tape 3 to the self-fusion superconducting wire 1. Therefore, it is possible to suppress an increase in the porosity of the superconducting coil.

[0034] Furthermore, the lower limit of the thickness of the insulating tape layer 32 of the insulating fusion tape 3 is preferably 10 μm or more, more preferably 15 μm or more, and the upper limit is preferably 50 μm or less, more preferably 40 μm or less. When the insulating tape layer 32 is 10 μm or more, the insulating tape layer 32 can impart a high breakdown voltage to the self-fusion superconducting wire 1 after repair. When the insulating tape layer 32 is 50 μm or less, with respect to the gaps S between the self-fusion superconducting wires 1 in the superconducting coil obtained by winding the self-fusion superconducting wire 1 after repair, it is possible to suppress an increase in the gaps S caused by attaching the insulating fusion tape 3 to the self-fusion superconducting wire 1. Therefore, it is possible to suppress an increase in the porosity of the superconducting coil.

[0035] Furthermore, the lower limit of the thickness of the self-fusing tape layer 33 of the insulating fusion tape 3 is preferably 10 μm or more, more preferably 35 μm or more, and the upper limit is preferably 50 μm or less, more preferably 40 μm or less. When the self-fusing tape layer 33 is 10 μm or more, the self-fusing tape layer 33 can impart sufficient self-fusing properties to the self-fusing superconducting wire 1 after repair. When the self-fusing tape layer 33 is 50 μm or less, the gaps S between the self-fusing superconducting wires 1 in the superconducting coil obtained by winding the self-fusing superconducting wire 1 after repair can be prevented from widening due to the application of the insulating fusion tape 3 to the self-fusing superconducting wire 1. This prevents an increase in the porosity of the superconducting coil.

[0036] In addition, although the above description shows a so-called round wire in which the cross section of the self-fusion superconducting wire 1 is circular, there is no particular limitation on the cross section of the self-fusion superconducting wire 1. For example, the self-fusion superconducting wire 1 may be a so-called rectangular wire in which the cross section is rectangular, or the self-fusion superconducting wire 1 may be a rectangle in which the cross section is rounded as shown in Fig. 6 .

[0037] 4 to 6, the insulating fusion tape 3 is wound around or approximately perpendicular to the longitudinal direction of the self-bonding superconducting wire 1, rather than being wound around or attached spirally. In this case, the length direction of the insulating fusion tape 3 is perpendicular or approximately perpendicular to the longitudinal direction of the self-bonding superconducting wire 1.

[0038] 4 to 6, the repaired self-bonding superconducting wire 1 preferably has an overlapping portion 3a of the insulating fusion tape 3. The overlapping portion 3a is a portion where the insulating fusion tape 3 that is wound around and attached to the self-bonding superconducting wire 1 overlaps in the thickness direction. By having the repaired self-bonding superconducting wire 1 have the overlapping portion 3a of the insulating fusion tape 3, the insulating fusion tape 3 can sufficiently and reliably cover the defective portion 14.

[0039] 4 to 6, the overlapping portion 3a of the insulating fusion tape 3 is provided at the position of the defective portion 14, but the overlapping portion 3a may be provided at a position other than the defective portion 14.

[0040] Next, a self-bonding superconducting wire for a superconducting coil according to an embodiment will be described.

[0041] An embodiment of the self-fusing superconducting wire for a superconducting coil comprises a superconducting wire, an insulating layer containing enamel covering the outer surface of the superconducting wire, a self-fusing layer covering the outer surface of the insulating layer, an adhesive tape layer, an insulating tape layer covering one main surface of the adhesive tape layer, and a self-fusing tape layer covering one main surface of the insulating tape layer, and an insulating fusion tape attached by the adhesive tape layer so as to cover defective areas present from the insulating layer to the surface of the self-fusing layer.

[0042] The configuration of the self-fusion superconducting wire of the embodiment is similar to the configuration of the self-fusion superconducting wire repaired by the repair method for self-fusion superconducting wire for superconducting coils of the above embodiment, that is, similar to the configuration of the self-fusion superconducting wire after repair shown in Figures 4 to 6. An insulating fusion tape 3 is attached to the self-fusion superconducting wire having a defective portion 14 so as to cover the defective portion 14.

[0043] The self-fusion superconducting wire of the embodiment is preferably a self-fusion superconducting wire repaired by the method for repairing a self-fusion superconducting wire for a superconducting coil of the above embodiment.

[0044] The self-bonding superconducting wire of this embodiment does not have a joint between the self-bonding superconducting wires even if a defective portion exists in the self-bonding superconducting wire, has sufficient insulating performance and self-bonding performance, and has a length necessary for manufacturing a superconducting coil. Furthermore, in a superconducting coil manufactured using the self-bonding superconducting wire of this embodiment, the occurrence of quenching is suppressed.

[0045] Next, the superconducting coil of the embodiment will be described.

[0046] 7 is an enlarged cross-sectional view of the superconducting coil of the embodiment, cut along a plane including the central axis of the barrel of the bobbin. For convenience, one side of the barrel 52 is shown.

[0047] A superconducting coil 50 of the embodiment includes a bobbin and a fused material 51 of self-fusion superconducting wire for a superconducting coil wound in a spiral shape around a body portion 52 of the bobbin. The self-fusion superconducting wire for a superconducting coil here is a self-fusion superconducting wire repaired by the repair method for self-fusion superconducting wire for a superconducting coil of the above embodiment, or a self-fusion superconducting wire for a superconducting coil of the above embodiment.

[0048] The self-fusing superconducting wire with insulating fusion tape 3 attached thereto is spirally wound around the body 52 of the reel, and then subjected to a fusion heat treatment at a temperature of 120°C or higher and 240°C or lower to fuse the self-fusing layers 13 together, the self-fusing tape layers 33 together, and the self-fusing layers 13 and the self-fusing tape layers 33 together, thereby obtaining the superconducting coil 50.

[0049] Regarding the state of the fused material 51, as shown in FIG. 7, the defective areas 14 and gaps S that are covered with the insulating fusion tape 3 and are not exposed may remain as empty spaces, or the fusion heat treatment during the manufacture of the superconducting coil may cause the resin that constitutes the self-fusing layer 13, the resin that constitutes the insulating tape layer 32, the resin that constitutes the self-fusing tape layer 33, etc. to flow into the spaces of the defective areas 14 and gaps S, thereby filling the defective areas 14 and gaps S with resin.

[0050] Even if a defect exists in the self-bonding superconducting wire, the superconducting coil of this embodiment can be manufactured using a self-bonding superconducting wire that does not have a joint between the self-bonding superconducting wires, has sufficient insulating performance and self-bonding performance, and has the length necessary for manufacturing a superconducting coil. Furthermore, since the outermost surface of the insulating fusion tape 3, i.e., the outermost surface of the insulating fusion tape 3 in a state where it is attached to the self-bonding superconducting wire, is the self-bonding tape layer 33, the self-bonding tape layer 33 of the insulating fusion tape 3 and the self-bonding layer 13 of the adjacent self-bonding superconducting wire are closely fused together. This makes it possible to suppress the occurrence of quenching in the superconducting coil.

[0051] According to the embodiment described above, by applying a specified insulating fusion tape to a self-fusing superconducting wire for a superconducting coil having a defective portion, it is possible to impart sufficient insulating performance and self-fusing performance to the repaired self-fusing superconducting wire for a superconducting coil without cutting and removing the defective portion of the self-fusing superconducting wire for a superconducting coil.

[0052] Although the embodiments have been described above, the present invention is not limited to the above embodiments, but includes all aspects encompassed by the concept and scope of the claims of the present disclosure, and can be modified in various ways within the scope of the present disclosure. [Example]

[0053] Next, examples and comparative examples will be described, but the present disclosure is not limited to these examples.

[0054] Example 1 A 10 mm wide insulating fusion tape with the configuration shown in Table 1 was obtained by applying a self-fusing varnish primarily composed of phenoxy resin to the surface opposite the adhesive tape layer of Kapton tape (manufactured by Toray DuPont) with a silicone-based adhesive adhesive, and then drying it. Next, a self-fusing superconducting wire with a diameter of 0.983 mm and a superconducting wire, which had a superconducting wire, an insulating layer, and a self-fusing layer, and had a defective portion, was attached to the defective portion by wrapping the insulating fusion tape around the self-fusing superconducting wire so that the length direction of the insulating fusion tape was approximately perpendicular to the longitudinal direction of the self-fusing superconducting wire and so that an overlapping portion of the insulating fusion tape was provided, and then the insulating fusion tape was attached using the adhesive tape layer. In this way, the defective portion of the self-fusing superconducting wire was repaired.

[0055] Next, the repaired self-fused superconducting wire was spirally wound around the body of a spool and subjected to fusion heat treatment at a temperature of 120°C or higher and 240°C or lower, thereby obtaining a superconducting coil.

[0056] (Comparative Example 1) Except for not applying insulating fusion tape to the self-fusion superconducting wire, the procedure was the same as in Example 1. In other words, the self-fusion superconducting wire of Comparative Example 1 corresponds to the self-fusion superconducting wire of Example 1 before repair.

[0057] (Comparative Example 2) The same procedure as in Example 1 was carried out except that an insulating adhesive tape having two layers, an insulating tape layer and a self-adhesive tape layer, each having a thickness shown in Table 1, was used.

[0058] (Comparative Example 3) The defective portion of the self-bonding superconducting wire was repaired in the same manner as in Example 1, except that the surface of the Kapton tape was not coated with self-bonding varnish, and a superconducting coil was manufactured.

[0059] Comparative Example 4 Defective portions of the self-fusing superconducting wire were repaired and superconducting coils were manufactured in the same manner as in Example 1, except that Kapton tape of the thickness shown in Table 1 was used and no self-fusing varnish was applied to the surface of the Kapton tape.

[0060] [Table 1]

[0061] [evaluation] The self-welded superconducting wires and superconducting coils obtained in the above examples and comparative examples were evaluated as follows. The results are shown in Table 2.

[0062] [1] Insulation properties The self-bonding superconducting wire was brought into contact with a brush for applying voltage, a voltage was applied to the self-bonding superconducting wire, and the resistance of the repaired part of the self-bonding superconducting wire was measured. A resistance value of 5 MΩ or more was ranked as good (○), and a resistance value of less than 5 MΩ was ranked as bad (×).

[0063] [2] Misalignment of insulating fusion tape relative to self-bonding superconducting wire The position of the insulating fusion tape attached to the self-bonding superconducting wire after winding on the spool was visually inspected to see if there was any deviation from the position of the insulating fusion tape attached to the self-bonding superconducting wire before winding on the spool. If there was no deviation of the insulating fusion tape before and after winding, it was evaluated as pass, and ranked as ×, and if there was deviation of the insulating fusion tape before and after winding, it was evaluated as fail.

[0064] [3] Misalignment of insulating fusion tape relative to the superconducting coil After winding, the insulating fusion tape attached to the self-bonding superconducting wire after fusion heat treatment was visually inspected for any deviation in the attachment position of the insulating fusion tape attached to the self-bonding superconducting wire after fusion heat treatment from the attachment position of the insulating fusion tape attached to the self-bonding superconducting wire before fusion heat treatment. If the insulating fusion tape was not displaced before and after fusion heat treatment, it was evaluated as passing and ranked as ○, and if the insulating fusion tape was displaced before and after fusion heat treatment, it was evaluated as failing and ranked as ×.

[0065] [Table 2]

[0066] As shown in Tables 1 and 2, in Example 1, the defective portions were repaired with an insulating fusion tape having a predetermined configuration, and the insulating properties of the repaired self-bonding superconducting wire were good. Furthermore, by using the repaired self-bonding superconducting wire, there was no displacement of the insulating fusion tape before and after winding, nor before and after fusion heat treatment. Thus, in Example 1, sufficient insulating performance and self-bonding performance were imparted to the repaired self-bonding superconducting wire. On the other hand, in Comparative Example 1, the defective portions of the self-bonding superconducting wire were not repaired, and therefore the insulating properties were poor. Furthermore, in Comparative Example 2, an insulating fusion tape without an adhesive tape layer was used, and therefore the insulating fusion tape was wound around the defective portions of the self-bonding superconducting wire but could not be attached. Furthermore, when a superconducting coil was manufactured using the self-bonding superconducting wire in this state, the insulating fusion tape moved during winding of the self-bonding superconducting wire, exposing the defective portions, and a sound superconducting coil could not be obtained. In addition, in Comparative Examples 3 and 4, the defective portions were not repaired with an insulating fusion tape having a predetermined configuration, and therefore, although the insulating properties of the repaired self-fusing superconducting wire were good, there was some displacement of the insulating fusion tape before and after winding and before and after the fusion heat treatment. Thus, in Comparative Examples 1 to 4, the repaired self-fusing superconducting wire could not be given sufficient insulating performance and self-fusing performance. [Explanation of symbols]

[0067] 1. Self-bonding superconducting wire for superconducting coils (self-bonding superconducting wire) 11 Superconducting wire 12 Insulating layer 13 Self-fusing layer 14 Defective parts 3 Insulating adhesive tape 3a Overlapping part 31 adhesive tape layer 32 insulating tape layers 33 Self-adhesive tape layer 50 Superconducting coil 51 Self-bonding superconducting wire for superconducting coils 52 Body of reel S Gap

Claims

1. A repair method for self-fusing superconducting wire for a superconducting coil, the self-fusing superconducting wire for a superconducting coil comprising a superconducting wire, an insulating layer including enamel covering the outer peripheral surface of the superconducting wire, and a self-fusing layer covering the outer peripheral surface of the insulating layer, the method comprising: attaching an insulating fusion tape comprising an adhesive tape layer, an insulating tape layer covering one main surface of the adhesive tape layer, and a self-fusing tape layer covering one main surface of the insulating tape layer to the self-fusing layer of the self-fusing superconducting wire for a superconducting coil by means of the adhesive tape layer, so as to cover a defective portion that exists from the insulating layer to the surface of the self-fusing layer.

2. 2. The repair method for a self-fusion superconducting wire for a superconducting coil according to claim 1, wherein the adhesive tape layer can be adhered to the self-fusion layer at room temperature.

3. 2. The repair method for a self-fusing superconducting wire for a superconducting coil according to claim 1, wherein the adhesive tape layer is made of a silicone-based adhesive or an acrylic-based adhesive.

4. 2. The repair method for a self-fusing superconducting wire for a superconducting coil according to claim 1, wherein the insulating tape layer is made of polyimide, polyester, fluororesin, or glass cloth.

5. 2. The repair method for a self-bonding superconducting wire for a superconducting coil according to claim 1, wherein the self-bonding tape layer is made of a phenoxy resin.

6. 2. The repair method for self-fusing superconducting wire for a superconducting coil according to claim 1, wherein the size of the insulating fusion tape attached to the self-fusing superconducting wire for a superconducting coil along the longitudinal direction of the self-fusing superconducting wire for a superconducting coil is 2 mm or more and 20 mm or less.

7. 2. The repair method for a self-fusion superconducting wire for a superconducting coil according to claim 1, wherein the insulating tape layer has a thickness of 10 μm or more and 50 μm or less.

8. 2. The repair method for a self-fusing superconducting wire for a superconducting coil according to claim 1, wherein the thickness of the self-fusing tape layer is 10 [mu]m or more and 50 [mu]m or less.

9. A superconducting wire, an insulating layer that covers an outer peripheral surface of the superconducting wire and includes enamel; a self-fusing layer covering an outer peripheral surface of the insulating layer; an insulating fusion tape comprising an adhesive tape layer, an insulating tape layer covering one main surface of the adhesive tape layer, and a self-fusing tape layer covering one main surface of the insulating tape layer, the adhesive tape layer being attached so as to cover a defective portion present from the insulating layer to the surface of the self-fusing layer; A self-bonding superconducting wire for a superconducting coil, comprising:

10. A reel; a self-fusion superconducting wire for a superconducting coil repaired by the repair method for a self-fusion superconducting wire for a superconducting coil according to any one of claims 1 to 8 or a fused product of the self-fusion superconducting wire for a superconducting coil according to claim 9, wound spirally around the body of the spool; A superconducting coil comprising:

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