Superconducting coil and method for manufacturing the same, and superconducting flat wire for superconducting coil

Abstract

The superconducting coil comprises: a winding frame; and at least two layers of superconducting flat wire material layers, wherein a superconducting flat wire material including a NbTi-based or Nb3Sn-based wire material whose surface is coated with copper or a copper alloy and has a substantially rectangular cross-section is spirally wound on an outer peripheral surface of the winding frame along a substantially circumferential direction of the winding frame, and the wire materials adjacent to each other in the axial direction of the winding frame are arranged in parallel in a state of being separated from each other, and the separated portions of the wire materials adjacent to each other in the same superconducting flat wire material layer and the two superconducting flat wire materials adjacent to each other are respectively located at the adjacent portions. The adjacent wires in the superconducting flat wire layer have at least a thermoplastic welding resin at the separation portions thereof, and when observed from a cross section including the axis of the winding frame, for at least one of the voids that can be divided by the outer surfaces of a total of three superconducting flat wires located in two adjacent superconducting flat wire layers and the voids that can be divided by the outer surfaces of a total of four superconducting flat wires, the void ratio, which is a ratio of the area occupied in at least two superconducting flat wire layers, is 4% or less.

Description

Technical Field

[0001] The present invention relates to a superconducting coil and a method for manufacturing the same, and a superconducting flat wire for the superconducting coil. Background Art

[0002] Superconducting wires are generally known to be materials that exhibit superconducting properties at extremely low temperatures. For such superconducting wires, if they are immersed in liquid helium after being wound on a winding frame to form a coil, they can be used as electromagnets. Superconducting wires have the advantage of being able to pass very large currents compared to ordinary copper wires and other electric wires, but when large currents pass through them, they may be subjected to large electromagnetic forces, causing vibrations and heat. If the temperature rises due to heat, even when the current is less than the critical current value of the superconducting wire, the superconducting state will be destroyed and become a normal conducting state (hereinafter referred to as "quench"), and the liquid helium will evaporate instantly. Therefore, measures are required to maintain the superconducting state and prevent quenching.

[0003] As a means of preventing the quench, for example, Patent Document 1 discloses a superconducting coil in which the winding portion of the superconducting coil is impregnated with epoxy resin and then the epoxy resin is cured to fix the superconducting coil. The cured epoxy resin is not susceptible to damage such as cracks or peeling even when subjected to repeated thermal cycles between room temperature and very low temperature (~4K), but if damage occurs, a quench is likely to occur.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 06-325932 Summary of the invention

[0007] Problems to be solved by the invention

[0008] However, the fixation of the above-mentioned superconducting rectangular wire by impregnation with epoxy resin and curing treatment requires cost and labor, and therefore, a method of manufacturing a superconducting coil capable of preventing quenching and a superconducting rectangular wire by a simpler method are desired.

[0009] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a superconducting flat wire for manufacturing a superconducting coil capable of preventing quenching by a simple method without performing impregnation and curing processes with a resin, a superconducting coil manufactured using the superconducting flat wire, and a manufacturing method thereof.

[0010] Means for solving problems

[0011] The inventors of the present application have conducted repeated and intensive studies to solve the above-mentioned problems. As a result, they have found that, for a superconducting flat wire for a superconducting coil having a NbTi-based or Nb3Sn-based wire whose surface is coated with copper or a copper alloy and a welding resin layer formed of a thermoplastic welding resin on the outer peripheral surface of the coated wire, by optimizing the average coating thickness of the welding resin layer constituting the superconducting flat wire and the curvature radius of the corner of the superconducting flat wire, and by using the superconducting flat wire to prepare a superconducting coil, quenching can be effectively suppressed, and the present invention has been completed. Specifically, the present invention provides the following technology.

[0012] [1] A superconducting coil comprising: a winding frame; and at least two layers of superconducting flat wire material, wherein a superconducting flat wire material having a substantially rectangular cross-section and comprising a NbTi-based or Nb3Sn-based wire material whose surface is coated with copper or a copper alloy is spirally wound on an outer peripheral surface of the winding frame in a substantially circumferential direction of the winding frame, and wherein adjacent wire materials in an axial direction of the winding frame are arranged in parallel in a state of being separated from each other, wherein the superconducting coil is characterized in that the separated portions of adjacent wire materials in the same superconducting flat wire material layer and the separated portions of adjacent wire materials in the respective layers are separated from each other. At least a thermoplastic welding resin is present at a separation portion between adjacent wires located in two adjacent superconducting flat wire layers, and when observed from a cross section including the axis of the winding frame, for at least one of gaps that can be divided by outer surfaces of a total of three superconducting flat wires located in the two adjacent superconducting flat wire layers and gaps that can be divided by outer surfaces of a total of four superconducting flat wires, the void ratio (V1) which is a ratio of area occupied in the at least two superconducting flat wire layers is 4% or less.

[0013] [2] The superconducting coil according to [1] above, characterized in that, when observed from a cross section including the axis of the winding frame, the gap is formed by outer surfaces of a total of three or a total of four superconducting flat wires located in the two adjacent superconducting flat wire layers and adjacent to each other.

[0014] [3] A superconducting coil comprising: a winding frame; and a superconducting flat wire layer, wherein a superconducting flat wire having a substantially rectangular cross-section and including a NbTi-based or Nb3Sn-based wire having a surface coated with copper or a copper alloy is spirally wound on an outer peripheral surface of the winding frame in a substantially circumferential direction of the winding frame, and the wires adjacent to each other in the axial direction of the winding frame are arranged in parallel in a state of being separated from each other, wherein the superconducting coil is characterized in that at least a thermoplastic welding resin is present at a portion where adjacent wires in the superconducting flat wire layer are separated from each other, and when observed from a cross section including the axis of the winding frame, a void space that can be partitioned by the outer surfaces of a total of two adjacent superconducting flat wires has a void ratio (V1) of 4% or less as a ratio of area occupied in the superconducting flat wire layer.

[0015] [4] The superconducting coil according to any one of [1] to [3] above, wherein the superconducting rectangular wire has a welding resin layer formed of the thermoplastic welding resin and covering an outer peripheral surface of the wire.

[0016] [5] The superconducting coil according to any one of [1] to [4] above, wherein the thermoplastic welding resin contains one or more selected from the group consisting of phenoxy resins, polyamide resins, and polyester resins.

[0017] [6] The superconducting coil according to [4] or [5], wherein the superconducting rectangular wire further comprises an insulating resin layer between the outer peripheral surface of the wire and the fusion resin layer.

[0018] [7] The superconducting coil according to [6] above, characterized in that the insulating resin layer contains one or more selected from the group consisting of polyvinyl formal resin, polyamide-imide resin, polyimide resin, polyester resin and polyurethane resin.

[0019] [8] The superconducting coil according to [6] or [7] above, wherein the average coating thickness of the insulating resin layer is not less than 0.005 mm and not more than 0.100 mm.

[0020] [9] The superconducting coil according to any one of [1] to [8], wherein the wire is a rectangular wire and the radius of curvature (R1) of the corner is not less than 0.1 mm and not more than 0.4 mm.

[0021]

[10] A superconducting coil according to any one of [1] to [9], characterized in that the wire is a flat wire and the radius of curvature (R1) of the corner portion satisfies the following equations (1) and (2):

[0022] [Mathematical formula 1]

[0023] 0<R1≤R1 max …Formula (1)

[0024]

[0025] In formula (2), A is 0.06.

[0026]

[11] A superconducting flat wire for a superconducting coil, the superconducting flat wire for a superconducting coil comprising: a NbTi-based or Nb3Sn-based wire having a surface coated with copper or a copper alloy; and a welding resin layer formed of a thermoplastic welding resin covering the outer peripheral surface of the wire, wherein the superconducting flat wire has an average coating thickness of not less than 0.005 mm and not more than 0.100 mm, and a curvature radius (R2) of a corner of the superconducting flat wire satisfies the following formula (3) and formula (4),

[0027] [Mathematical formula 2]

[0028] 0<R2≤R2 max …Formula (3)

[0029]

[0030] In formula (4), B is 0.06.

[0031]

[12] The superconducting rectangular wire according to

[11] above, wherein the average coating thickness of the welding resin layer is not less than 0.01 mm and not more than 0.07 mm.

[0032]

[13] The superconducting rectangular wire according to

[11] or

[12] , wherein the thermoplastic welding resin contains one or more selected from the group consisting of phenoxy resins, polyamide resins, and polyester resins.

[0033]

[14] The superconducting rectangular wire according to any one of

[10] to

[13] , further comprising an insulating resin layer formed of an insulating resin between the outer peripheral surface of the wire and the fusion resin layer.

[0034]

[15] The superconducting rectangular wire according to

[14] above, characterized in that the insulating resin contains one or more selected from the group consisting of polyvinyl formal resin, polyamide-imide resin, polyimide resin, polyester resin and polyurethane resin.

[0035]

[16] The superconducting rectangular wire according to

[14] or

[15] , wherein the average coating thickness of the insulating resin layer is not less than 0.005 mm and not more than 0.100 mm.

[0036]

[17] The superconducting flat wire according to any one of

[11] to

[16] , wherein the wire is a flat wire and the curvature radius (R1) of the corner portion is not less than 0.1 mm and not more than 0.4 mm.

[0037]

[18] The superconducting flat wire according to any one of

[11] to

[17] , wherein the wire is a flat wire and the curvature radius (R1) of the corner portion satisfies the following equations (1) and (2):

[0038] [Mathematical formula 3]

[0039] 0<R1≤R1 max …Formula (1)

[0040]

[0041] In formula (2), A is 0.06.

[0042]

[19] A method for manufacturing a superconducting coil, comprising: a winding step of spirally winding the superconducting flat wire described in any one of

[10] to

[18] on an outer peripheral surface of a winding frame along a substantially circumferential direction of the winding frame to form a coil having at least two layers of superconducting flat wires arranged in parallel in a state where the wires are adjacent to each other in the axial direction of the winding frame and are separated from each other; and

[0043] A heat treatment step, wherein, when the thermoplastic welding resin is an amorphous resin, the coil formed in the winding step is subjected to a heat treatment at a temperature not less than the glass transition temperature of the amorphous resin and not more than 300°C, or, when the thermoplastic welding resin is a crystalline resin, the coil formed in the winding step is subjected to a heat treatment at a temperature not less than the melting point of the crystalline resin and not more than 300°C.

[0044]

[20] A method for manufacturing a superconducting coil, comprising: a winding step of spirally winding the superconducting flat wire described in any one of

[10] to

[18] on an outer peripheral surface of a winding frame along a substantially circumferential direction of the winding frame to form a coil having one superconducting flat wire layer in which adjacent wires are arranged in parallel in a state of being separated from each other in the axial direction of the winding frame; and

[0045] A heat treatment step, wherein, when the thermoplastic welding resin is an amorphous resin, the coil formed in the winding step is subjected to a heat treatment at a temperature not less than the glass transition temperature of the amorphous resin and not more than 300°C, or, when the thermoplastic welding resin is a crystalline resin, the coil formed in the winding step is subjected to a heat treatment at a temperature not less than the melting point of the crystalline resin and not more than 300°C.

[0046] Effects of the Invention

[0047] According to the present invention, it is possible to provide a superconducting flat wire for manufacturing a superconducting coil capable of preventing quenching by a simple method without performing impregnation and curing processes with a resin, a superconducting coil manufactured using the superconducting flat wire, and a manufacturing method thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is a cross-sectional view of the superconducting coil according to the first embodiment cut along a plane including the axis of the winding frame.

[0049] Figure 2 It is used to illustrate Figure 1 A diagram showing a method for calculating the void fraction (V1) in a superconducting coil.

[0050] Figure 3 It is a cross-sectional view for explaining the arrangement relationship between two adjacent superconducting rectangular wire layers constituting the superconducting coil according to the second embodiment.

[0051] Figure 4 It is a cross-sectional view for explaining the arrangement relationship between two adjacent superconducting rectangular wire layers constituting the superconducting coil according to the third embodiment.

[0052] Figure 5 This is a cross-sectional view of the superconducting coil according to the fourth embodiment cut along a plane including the axis of the winding frame.

[0053] Figure 6 It is used to illustrate Figure 5 A diagram showing a method for calculating the void fraction (V1) in a superconducting coil.

[0054] Figure 7 It is a cross-sectional view of the superconducting rectangular wire for superconducting coil according to the first embodiment.

[0055] Figure 8 It is a cross-sectional view of a superconducting rectangular wire for a superconducting coil according to a second embodiment.

[0056] Fig. 9 This is a diagram for explaining an example of a method for manufacturing a superconducting coil.

[0057] Fig.10 It is a diagram for explaining another example of the method for manufacturing a superconducting coil.

[0058] Fig.11 It is a cross-sectional view for explaining the dimensions of the superconducting rectangular wire for superconducting coils produced in Examples. DETAILED DESCRIPTION

[0059] Hereinafter, preferred embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments.

[0060] 1. Superconducting coil

[0061] The superconducting coil of the present invention comprises: a winding frame; and at least two layers of superconducting flat wire material layers, wherein a superconducting flat wire material including a NbTi-based or Nb3Sn-based wire material whose surface is coated with copper or a copper alloy and has a substantially rectangular cross-section is spirally wound on an outer peripheral surface of the winding frame along a substantially circumferential direction of the winding frame, and the wire materials adjacent to each other in the axial direction of the winding frame are arranged in parallel in a state of being separated from each other, and the separated portions of the wire materials adjacent to each other in the same superconducting flat wire material layer ... At least a thermoplastic welding resin is present at the separation portions of the adjacent wires in two superconducting flat wire layers, and when observed from a cross section including the axis of the winding frame, for at least one of the voids that can be divided by the outer surfaces of a total of three superconducting flat wires located in the two adjacent superconducting flat wire layers and the voids that can be divided by the outer surfaces of a total of four superconducting flat wires, the void ratio (V1) which is a ratio of the area occupied in the at least two superconducting flat wire layers is 4% or less.

[0062] In addition, the superconducting coil of the present invention comprises: a winding frame; and a superconducting flat wire layer, wherein a superconducting flat wire including a NbTi-based or Nb3Sn-based wire having a surface coated with copper or a copper alloy and having a substantially rectangular cross-section is spirally wound on an outer peripheral surface of the winding frame in a substantially circumferential direction of the winding frame, and the wires adjacent to each other in the axial direction of the winding frame are arranged in parallel in a state of being separated from each other, at least a thermoplastic welding resin is present at a portion where the adjacent wires in the superconducting flat wire layer are separated from each other, and when observed from a cross section including the axis line of the winding frame, a void fraction (V1) as a ratio of an area occupied in the superconducting flat wire layer by voids that can be partitioned by outer surfaces of a total of two adjacent superconducting flat wires is 4% or less.

[0063] Figure 1 This is a cross-sectional view of the superconducting coil according to the first embodiment cut along a plane including the axis of the winding frame. Figure 1 The superconducting coil 100 shown in the figure includes: a winding frame 60; and two layers of superconducting flat wire layers L1 and L2, which are formed by spirally winding a superconducting flat wire 10' including a NbTi-based or Nb3Sn-based wire 1' whose surface is coated with copper or a copper alloy and has a substantially rectangular cross section on the outer peripheral surface of the winding frame 60 along the substantially circumferential direction of the winding frame 60, and arranging the wires 1' adjacent to each other in the axial direction of the winding frame in a mutually separated state in parallel. The superconducting flat wire layers L1 and L2 are stacked in the radial direction of the winding frame 60. The superconducting flat wire layer L1 is provided on the outer side of the superconducting flat wire layer L2, and the superconducting flat wire layer L2 is provided on the outer peripheral surface of the winding frame 60 on the inner side of the superconducting flat wire layer L1. The following describes an example in which the superconducting coil 100 includes two layers of superconducting flat wire layers L1 and L2, but the superconducting coil 100 may include three or more layers of superconducting flat wire layers.

[0064] The winding frame 60 includes, for example, a solid or hollow cylindrical main body 61 and flange-shaped wing plates 62 and 63 provided at both axial ends of the main body 61. The wire 1' is wound around the outer peripheral surface of the main body 61 of the winding frame 60. Figure 1 In the cross-sectional view taken along a plane including the axis of the winding frame, that is, in the longitudinal cross-sectional view of the superconducting coil including the axis of the winding frame, the outer peripheral surface of the main body portion 61 corresponds to an outer peripheral line 61 a described later.

[0065] At least the thermoplastic welding resin 2' is present at the separation portion S1 between the wires 1'-1 and 1'-2 adjacent to each other in the axial direction of the winding frame in the same superconducting flat wire layer L1 or L2 and at the separation portion S2 between the wires 1'-1 and 1'-6 adjacent to each other in the radial direction of the winding frame in two superconducting flat wire layers L1 and L2 adjacent to each other in the radial direction of the winding frame. That is, the surface of the wire 1' is completely covered with the thermoplastic welding resin 2', and the wires 1' do not contact each other. Furthermore, when observed from a cross section including the axis of the winding frame 60, for at least one of the gaps that can be formed by the outer surfaces of a total of three superconducting flat wires located in two adjacent superconducting flat wire layers and adjacent to each other in the axial or radial direction of the winding frame, and the gaps that can be formed by the outer surfaces of a total of four superconducting flat wires, the void ratio (V1) which is the ratio of the area occupied in the two superconducting flat wire layers L1 and L2 is less than 4%.

[0066] like Figure 1 As shown in FIG. 1 , the so-called gaps formed by the outer surfaces of the three superconducting flat wires in total refer to the gaps 41 formed by the outer surfaces of the three superconducting flat wires 1'-1, 1'-2, and 1'-6 in total, and the gaps 42, ..., and 48 formed by the outer surfaces of the three superconducting flat wires 1'-2, 1'-6, and 1'-7 in total. In addition, as described later Figure 4 As shown, the so-called gaps that can be formed by the outer surfaces of the total four superconducting flat wires refer to the gaps 41b that can be formed by the outer surfaces of the total four superconducting flat wires 1b'-1, 1b'-2, 1b'-6, and 1b'-7, the gaps 42b, ..., and gaps 44b that can be formed by the outer surfaces of the total four superconducting flat wires 1'-2, 1b'-3, 1'-7, and 1'-8.

[0067] When observing from a cross section including the axis of the winding frame 60, the gaps may be only gaps that can be divided by the outer surfaces of a total of three superconducting flat wires, or only gaps that can be divided by the outer surfaces of a total of four superconducting flat wires, or gaps that can be divided by the outer surfaces of a total of three and a total of four superconducting flat wires (mixed). In addition, in the superconducting coil 100, there is a case where the state of the gaps in the cross section including the axis of the winding frame 60 changes if the angle of the plane including the axis of the winding frame 60 relative to the axis of the winding frame 60 is different. For example, in the superconducting coil 100, there is a case where only gaps that can be divided by the outer surfaces of a total of three superconducting flat wires are observed in a certain cross section including the axis of the winding frame 60, and only gaps that can be divided by the outer surfaces of a total of four superconducting flat wires are observed in another cross section including the axis of the winding frame 60.

[0068] Here, the method for calculating the area (S) of at least two layers of superconducting flat wire material when calculating the void ratio (V1) is described. Figure 2 As shown, when viewed from a cross section including the axis of the winding frame, the line farthest from the outer peripheral line 61a among all the straight lines tangent to or intersecting the superconducting flat wires 10' constituting the superconducting flat wire layer L1 as the outermost layer is set as line P. Figure 2 As shown, the line P is parallel to the outer peripheral line 61a and is tangent to all of the superconducting flat wires 10' constituting the superconducting flat wire layer L1. The area surrounded by the line P, the outer peripheral line 61a of the main body 61 of the winding frame 60, and the wing plate parts 62 and 63 of the winding frame 60 is defined as the area (S) ( Figure 2 On the other hand, the area of ​​the void (Sv) is as described above. Figure 1 The gaps 41, 42, ... 48 shown in Figure 4 The gaps 51 and 52 (in the gaps 41b, 42b, ... 48b) formed between the two wing portions 62 and 63 of the winding frame 60 and the two side surfaces of the two superconducting flat wire layers L1 and L2 respectively facing the two wing portions 62 and 63 are formed. Figure 1 ) are respectively represented by the area surrounded by the double-dashed line. ) are not included in the area of ​​the void (Sv), and all the inner voids 71 ​​formed between the superconducting flat wire layer L2 and the outer peripheral line 61a of the main body of the winding frame and all the outer voids 72 formed between the superconducting flat wire layer L1 as the outermost layer and the wire P are included in the area of ​​the void (Sv). And the void ratio (V1) is calculated by V1 (%) = (Sv / S) × 100. From the viewpoint of suppressing quenching, it is preferable to fill the voids 51, 52 with a resin such as a thermoplastic welding resin.

[0069] According to such a superconducting coil 100, quenching can be effectively prevented even when a large current flows through the superconducting coil 100. In addition, cracks are not generated in the thermoplastic welding resin 2' due to thermal stress generated when the coil is repeatedly heated and cooled or when a quench occurs. Therefore, the superconducting coil 100 can be used as a superconducting coil having a small number of training quenches and high stability.

[0070] [Superconducting flat wire]

[0071] The superconducting rectangular wire 10' comprises at least a wire 1' described later and a welding resin layer 2' formed of a thermoplastic welding resin covering the outer peripheral surface of the wire 1', and an insulating resin may be further provided therebetween as desired.

[0072] In the superconducting coil 100 , the winding direction of the superconducting rectangular wire 10 ′ with respect to the winding frame 60 is not particularly limited, and the winding direction may be either clockwise or counterclockwise.

[0073] The number of windings of the superconducting rectangular wire 10 ′ around the winding frame 60 is not particularly limited.

[0074] The number of superconducting rectangular wire layers relative to the winding frame 60 is not particularly limited, and may be at least one layer.

[0075] [Wire]

[0076] The wire material 1 ′ is a NbTi-based or Nb 3 Sn-based wire material whose surface is coated with copper or a copper alloy.

[0077] The shape of the wire 1' is not particularly limited, and for example, a round wire, a flat wire, etc. can be used. Among them, by using a flat wire, the gap can be reduced and a higher current density can be obtained. In addition, in the case of manufacturing by the manufacturing method described later, since the welding area (contact area) between the wires becomes larger, the welding force can be increased.

[0078] When a flat wire is used as the wire 1', the curvature radius (R1) of the corner in the cross section (i.e., the cross section including the axis of the winding frame of the superconducting coil) is preferably 0.1 mm or more and 0.4 mm or less. By setting the curvature radius (R1) of the corner to 0.1 mm or more, it is possible to prevent the wires from getting caught on each other when winding the superconducting coil and causing damage to the surface of the wire, and by setting it to 0.4 mm or less, it is possible to reduce the void ratio in the superconducting coil.

[0079] When a flat wire is used as the wire 1', the thickness (short side) in the cross section of the wire 1' is not particularly limited, and is, for example, 0.2 mm to 3 mm. The width (long side) is not particularly limited, and is, for example, 0.4 mm to 10 mm.

[0080] When a rectangular wire is used as the wire 1', the radius of curvature (R1) of the corner of the wire 1' preferably satisfies the following formula (1) and formula (2). In the formula (2), A is 0.06, preferably 0.04.

[0081] [Formula 4]

[0082] 0<R1≤R1 max …Formula (1)

[0083]

[0084] [Welding resin layer]

[0085] The welding resin layer 2' is a layer formed of a thermoplastic welding resin that covers the outer peripheral surface of the wire 1' and can be welded together by heating.

[0086] The thermoplastic welding resin is not particularly limited, but is preferably one or more selected from phenoxy resins, polyamide resins, and polyester resins because the welding process can be performed at a relatively low temperature and good welding properties can be expected.

[0087] The phenoxy resin is also called polyhydroxy ether, has a molecular weight of 10,000 or more, and its chemical structure is shown below as formula (a). The phenoxy resin used in the present invention can be used in the form of a varnish dissolved in a solvent such as m-cresol, but is not particularly limited.

[0088] [Chemical formula 1]

[0089]

[0090] The polyamide resin preferably uses a polyamide random copolymer having a lower melting point than polyamide alone, for example, polyamide 6 / polyamide 12 copolymer, polyamide 6 / polyamide 11 copolymer, polyamide 6 / polyamide 66 copolymer, wherein polyamide 6 / polyamide 12 copolymer and polyamide 6 / polyamide 11 copolymer are more preferred due to their low melting points. The melting point of the polyamide copolymer varies according to the composition ratio of each resin, and the composition ratio with the lowest melting point can be selected for use. For example, in the polyamide 6 / polyamide 11 copolymer, the melting point is the lowest at 150° C. when polyamide 6 is 30% by weight. The polyamide resin used in the present invention can be used in the form of a varnish dissolved in a solvent such as meta-cresol, but is not particularly limited.

[0091] [Insulating resin layer]

[0092] Although not an essential component, in order to further improve the insulation of the wire material to the outside, it is preferable to further include an insulating resin layer made of an insulating resin between the outer peripheral surface of the wire material and the welding resin layer.

[0093] Figure 3 FIG. 2 is a cross-sectional view of a superconducting rectangular wire layer portion of a superconducting coil according to a second embodiment. Figure 3 This is a cross-sectional view obtained by observing the axis of the winding frame, omitting the winding frame and showing only one side of the superconducting flat wire layer. The welding resin layer 2a' is welded. In addition, an insulating resin layer 3a is arranged between the welding resin layer 2a' and the outer peripheral surface of the wire 1a'-1. The surface of the wire 1a' is completely covered by the insulating resin layer 3a.

[0094] The insulating resin is not particularly limited as long as it can insulate the current from the wire 1a'-1 to the outside. The insulating resin layer is preferably formed of one or more selected from polyvinyl formal resin, polyamideimide resin, polyimide resin, polyester resin and polyurethane resin, which are expected to have relatively good insulation properties.

[0095] The average coating thickness of the insulating resin layer 3a is not particularly limited. In order to ensure the insulation properties, it is preferably 0.005 mm or more, and more preferably 0.01 mm or more. In addition, the average coating thickness of the insulating resin layer 3a is preferably 0.100 mm or less, more preferably 0.07 mm or less, and further preferably 0.05 mm or less. If the average coating thickness of the insulating resin layer is less than 0.005 mm, sufficient insulation properties cannot be expected due to insufficient resin. If it is thicker than 0.100 mm, the wire space factor decreases and the current density of the coil decreases, which is not ideal. The average coating thickness of the insulating resin layer 3a is measured by the end of the cross section (the portion not clamped between the wires) when cut with a plane containing the axis of the winding frame 60.

[0096] However, if Figure 1 , Figure 3 As shown, when viewed from a cross section including the axis of the winding frame, the superconducting coil ( Figure 4 ), in the case of a superconducting coil in which the gaps 41 are divided by the outer surfaces of a total of three superconducting flat wires (e.g., superconducting flat wires 1'-1, 1'-2, and 1'-6) located in two adjacent superconducting flat wire layers L1 and L2 and adjacent to each other, the gaps 41, 42, ..., 48 are not arranged in a straight line along the radial direction of the winding frame, but are alternately staggered inside and outside in the radial direction of the winding frame. Figure 1 , Figure 3In the superconducting coil shown, the positions of the corners of the superconducting flat wires 10' and 1' constituting the superconducting flat wire layer L1 and the positions of the corners of the superconducting flat wires 10' and 1' constituting the superconducting flat wire layer L2 (adjacent to the superconducting flat wire layer L1 on the radial inner side of the winding frame) are not consistent in the axial direction of the winding frame, but are completely offset. Therefore, the development of cracks between gaps can be effectively suppressed, and the mechanical strength can be improved.

[0097] It should be noted that if Figure 4 As shown, when the gap 41b is formed by dividing the outer surfaces of a total of four superconducting flat wires (for example, superconducting flat wires 1b'-1, 1b'-2, 1b'-6, and 1b'-7) located in two adjacent superconducting flat wire layers L1b and L2b when observed from a cross section including the axis of the winding frame, the gaps 41b, 42b, 43b, and 44b are arranged in a straight line along the radial direction of the winding frame, but have a strength sufficient to withstand normal use of the superconducting coil.

[0098] Figure 5 This is a cross-sectional view of the superconducting coil according to the fourth embodiment cut along a plane including the axis of the winding frame. Figure 6 It is used to illustrate Figure 5 The figure is a method for calculating the void ratio (V1) in the superconducting coil. In the above, a superconducting coil having at least two layers of superconducting flat wire material layers L1 and L2 (L1b, L2b) on the outer peripheral wire 61a of the main body 61 of the winding frame 60 is shown, but the superconducting coil 100 of this embodiment has only one layer of superconducting flat wire material layer L2 on the outer peripheral wire 61a of the main body 61. In addition, similarly to the above, Figures 5-6 The superconducting coil 100 shown may include an insulating resin layer 3 a .

[0099] Figures 5-6 The superconducting coil 100 shown in the figure comprises: a winding frame 60; and a single superconducting flat wire layer L2, wherein a superconducting flat wire 10' including a NbTi-based or Nb3Sn-based wire 1' coated with copper or a copper alloy and having a substantially rectangular cross section is spirally wound on the outer peripheral surface of the winding frame 60 along the substantially circumferential direction of the winding frame 60, and the wires 1' adjacent to each other in the axial direction of the winding frame are arranged in parallel in a state of being separated from each other. The superconducting flat wire layer L2 is provided on the outer peripheral surface of the winding frame 60.

[0100] In the superconducting flat wire layer L2, at least the thermoplastic welding resin 2' is present at the separation portion S1 between the wires 1'-6 and 1'-7 adjacent to each other in the axial direction of the winding frame. That is, the surface of the wire 1' is completely covered with the thermoplastic welding resin 2', and the wires 1' are not in contact with each other. Furthermore, when observing from a cross section including the axis of the winding frame 60, the void space that can be formed by the outer surfaces of a total of two superconducting flat wires adjacent to each other in the axial direction of the winding frame, i.e., the void ratio (V1) is 4% or less in terms of the area ratio occupied in one layer of the superconducting flat wire layer L2.

[0101] Here, the calculation method of the area (S) of one superconducting flat wire layer when calculating the void ratio (V1) in this embodiment is described. Figure 6 As shown, when viewed from a cross section including the axis of the winding frame, the line farthest from the outer peripheral line 61a among all the straight lines tangent to or intersecting the superconducting flat wires 10' constituting the superconducting flat wire layer L2 is set as line P. Figure 6 As shown, the line P is parallel to the outer peripheral line 61a and is tangent to all of the superconducting flat wires 10' constituting the superconducting flat wire layer L2. The area surrounded by the line P, the outer peripheral line 61a of the main body 61 of the winding frame 60, and the wing plate parts 62 and 63 of the winding frame 60 is defined as area (S) ( Figure 6 On the other hand, the area of ​​the void (Sv) is the sum of all inner voids 71 ​​formed between the superconducting flat wire layer L2 and the outer peripheral line 61a of the main body of the winding frame and all outer voids 72 formed between the superconducting flat wire layer L2 and the wire P. The void 51 formed between the two wing portions 62, 63 of the winding frame 60 and the two side surfaces of the superconducting flat wire layer L2 respectively facing the two wing portions 62, 63 (here, the configuration in which the void 51 is formed between the wing portion 62 and the side surface of the superconducting flat wire layer L2 and not formed between the wing portion 63 and the side surface of the superconducting flat wire layer L2) is not included in the area of ​​the void (Sv). In addition, the void ratio (V1) is calculated as V1 (%) = (Sv / S) × 100. From the viewpoint of suppressing quenching, it is preferable to fill the void 51 with a resin such as a thermoplastic welding resin.

[0102] According to such a single-layer superconducting coil 100, similarly to the above-mentioned multi-layer superconducting coil, quenching can be effectively prevented even when a large current is passed through the superconducting coil 100, and cracks are not generated in the thermoplastic welding resin 2' due to thermal stress generated when the coil is repeatedly heated and cooled or when a quench occurs, so that the single-layer superconducting coil 100 can be used as a superconducting coil with a small number of training quenches and high stability.

[0103] 2.Superconducting flat wire for superconducting coil

[0104] The superconducting flat wire for superconducting coils of the present invention comprises: a NbTi-based or Nb3Sn-based wire having a surface coated with copper or a copper alloy; and a welding resin layer formed of a thermoplastic welding resin covering the outer peripheral surface of the wire, wherein the average coating thickness of the welding resin layer is 0.005 mm to 0.100 mm, and the curvature radius (R2) of the corner of the superconducting flat wire satisfies the following formula (3) and formula (4). B in formula (3) is 0.06, preferably 0.04.

[0105] [Mathematical formula 5]

[0106] 0<R2≤R2 max …Formula (3)

[0107]

[0108] Figure 7 This is a cross-sectional view of a superconducting flat wire for superconducting coils according to the first embodiment of the present invention. The superconducting flat wire for superconducting coils 10 comprises: a wire 1 of NbTi or Nb3Sn with copper or copper alloy coated on the surface; and a welding resin layer 2 formed of a thermoplastic welding resin coating the outer peripheral surface of the wire 1, wherein the average coating thickness of the welding resin layer 2 is 0.005 mm or more and 0.100 mm or less, and the curvature radius (R2) of the corner of the superconducting flat wire 10 satisfies the above formula (3) and the above formula (4). The cross section of the superconducting flat wire 10 is a substantially rectangular flat wire.

[0109] The outer peripheral surface of the wire 1 of the superconducting flat wire 10 is coated with the fusion resin layer 2 in advance by a simple method including the following steps: a winding step in which the superconducting flat wire 10 is spirally wound on the outer peripheral surface of the winding frame along the substantially circumferential direction of the winding frame to form a winding frame having the wires 1, 1 adjacent to each other in the axial direction of the winding frame and arranged in parallel in a state of being separated from each other. and a heat treatment step, wherein, when the thermoplastic welding resin is an amorphous resin, the coil formed in the winding step is heat treated at a temperature above the glass transition temperature of the amorphous resin (preferably a temperature 30°C or higher than the glass transition temperature) and below 300°C, or when the thermoplastic welding resin is a crystalline resin, the coil formed in the winding step is heat treated at a temperature above the melting point of the crystalline resin and below 300°C. If the welding treatment temperature exceeds 300°C, the performance of the superconducting wire may deteriorate due to heating, which is not desirable.

[0110] In particular, by setting the average coating thickness of the welding resin layer 2 to 0.005 mm or more and 0.100 mm or less and by setting the radius of curvature (R2) of the corner of the superconducting rectangular wire 10 to satisfy the above-mentioned formula (3) and the above-mentioned formula (4), the void ratio (V1) of the superconducting coil manufactured using the superconducting rectangular wire 10 is set to 4% or less, and as a result, the superconducting coil 100 can be prevented from quenching.

[0111] [Wire]

[0112] Since the wire 1 is the same as the wire used in the above-mentioned superconducting coil, the description here is omitted.

[0113] [Welding resin layer]

[0114] The welding resin layer 2 is a layer formed of the same resin as the thermoplastic welding resin used in the above-mentioned superconducting coil, and covers the outer peripheral surface of the wire 1 .

[0115] Specifically, the thermoplastic welding resin constituting the welding resin layer 2 is not particularly limited, but is preferably one or more selected from phenoxy resins, polyamide resins, and polyester resins from the viewpoint that welding can be performed at relatively low temperatures and good welding properties can be expected.

[0116] The average coating thickness of the welding resin layer 2 is not particularly limited, and can be 0.005 mm to 0.100 mm, preferably 0.01 mm or more. In addition, the average coating thickness of the welding resin layer 2 is preferably 0.07 mm or less, and more preferably 0.05 mm or less. If the average coating thickness of the welding resin layer 2 is less than 0.005 mm, sufficient welding force cannot be expected due to insufficient resin amount. On the other hand, if the average coating thickness becomes thicker than 0.100 mm, there is a possibility that the wire space factor is reduced and the current density of the coil is reduced, so it is not ideal. It should be noted that the average coating thickness of the welding resin layer 2 in the case of constituting the superconducting coil 100 is measured from the end of the cross section when cut by a plane containing the axis of the winding frame 60 (the portion not clamped between the wires).

[0117] [Insulating resin layer]

[0118] Although not an essential component, in order to further improve the insulation of the wire material to the outside, it is preferable to further include an insulating resin layer made of an insulating resin between the outer peripheral surface of the wire material and the welding resin layer.

[0119] Figure 8 FIG. 2 is a cross-sectional view of a superconducting rectangular wire for a superconducting coil according to a second embodiment of the present invention. Figure 8 In the embodiment, the superconducting rectangular wire 10a further includes an insulating resin layer 3a between the outer peripheral surface of the wire 1a and the welding resin layer 2a.

[0120] The insulating resin layer 3a is not particularly limited as long as it can insulate the current from the wire 1a to the outside. From the viewpoint of being able to expect better insulation, the insulating resin layer 3a is preferably formed of one or more selected from polyvinyl formal resin, polyamide-imide resin, polyimide resin, polyester resin and polyurethane resin.

[0121] The average coating thickness of the insulating resin layer 3a is not particularly limited. In order to ensure the insulation properties, it is preferably 0.005 mm or more, and more preferably 0.01 mm or more. In addition, the average coating thickness of the insulating resin layer 3a is preferably 0.100 mm or less, more preferably 0.07 mm or less, and further preferably 0.05 mm or less. If the average coating thickness of the insulating resin layer is less than 0.005 mm, sufficient insulation properties cannot be expected due to insufficient resin content. If it becomes thicker than 0.100 mm, the wire space factor decreases and the current density of the coil decreases, which is not ideal. It should be noted that the average coating thickness of the insulating resin layer 3a in the case of constituting the superconducting coil 100 is measured by the end of the cross section (the portion not clamped between the wires) when cut by a plane containing the axis of the winding frame 60.

[0122] [Manufacturing of superconducting flat wire for superconducting coils]

[0123] Regarding the superconducting rectangular wire for superconducting coils, for example, the method of coating with a welding resin layer is not particularly limited, and examples thereof include a method of coating with a varnish obtained by dissolving a thermoplastic welding resin in a solvent and performing a resin sintering step. The method of coating with an insulating resin layer is not particularly limited, and examples thereof include a method of coating with a varnish obtained by dissolving an insulating resin in a solvent and performing a resin sintering step.

[0124] It should be noted that, as another effect of the method for using the superconducting flat wire, the following effect can be obtained: when used to prepare a special-shaped coil such as a saddle coil other than a solenoid coil, the superconducting flat wires are brought into local contact with each other in the middle of the coil preparation, and the portion is heated to temporarily fix them, thereby improving the winding operability in a manner that does not cause tension relaxation in the winding.

[0125] 3. Manufacturing method of superconducting coil

[0126] The method for manufacturing a superconducting coil of the present invention includes the following steps: a winding step in which the superconducting flat wire 10 is spirally wound on the outer peripheral surface of the winding frame 60 along the substantially circumferential direction of the winding frame 60 to form a coil having at least two layers of superconducting flat wire material layers in which the wire materials 1 adjacent to each other in the axial direction of the winding frame 60 are arranged in parallel in a state separated from each other; and a heat treatment step in which, when the thermoplastic welding resin is an amorphous resin, the coil formed in the winding step is heat treated at a temperature of not less than the glass transition temperature of the amorphous resin (preferably a temperature 30° C. or higher than the glass transition temperature) and not more than 300° C., or when the thermoplastic welding resin is a crystalline resin, the coil formed in the winding step is heat treated at a temperature of not less than the melting point of the crystalline resin and not more than 300° C. By the above simple method, the superconducting coil 100 capable of preventing quenching can be manufactured without performing treatments such as impregnation and curing with a resin. In addition, as amorphous resin, a phenoxy resin, a polyester resin, etc. are mentioned.

[0127] Below, use Fig. 9 In the winding process, when viewed from a cross section including the axis of the winding frame, the winding frame is formed Fig. 9 In the configuration shown in (a), the superconducting flat wire 10 is wound in at least two layers along the approximate circumferential direction of the winding frame 60 on the outer peripheral surface of the winding frame 60 to form a coil. Next, in the heat treatment step, when the thermoplastic welding resin is an amorphous resin, the coil is heated at a temperature not less than the glass transition temperature of the amorphous resin (preferably a temperature not less than 30°C higher than the glass transition temperature) and not more than 300°C, or when the thermoplastic welding resin is a crystalline resin, the coil is heated at a temperature not less than the melting point of the crystalline resin and not more than 300°C, thereby the thermoplastic welding resins 2-1, 2-2, ..., 2-10 are melted and mutually welded, as shown in FIG. Fig. 9 As shown in (b), a fusion resin layer 2' is formed.

[0128] in addition, Figures 5-6The manufacturing method of the superconducting coil of the present invention includes the following steps: a winding step in which the superconducting flat wire 10 is spirally wound on the outer peripheral surface of the winding frame 60 along the substantially circumferential direction of the winding frame 60 to form a coil having one superconducting flat wire layer in which the wires 1 adjacent to each other in the axial direction of the winding frame 60 are arranged in parallel in a state of being separated from each other; and a heat treatment step in which, when the thermoplastic welding resin is an amorphous resin, the coil formed in the winding step is heated at a temperature of not less than the glass transition temperature of the amorphous resin (preferably a temperature 30° C. or higher than the glass transition temperature) and not more than 300° C., or when the thermoplastic welding resin is a crystalline resin, the coil formed in the winding step is heated at a temperature of not less than the melting point of the crystalline resin and not more than 300° C. By such a simple method, the superconducting coil 100 capable of preventing quenching can be manufactured without performing treatments such as impregnation and curing with a resin. In addition, as amorphous resin, a phenoxy resin, a polyester resin, etc. are mentioned.

[0129] The following uses Fig.10 In the winding process, when viewed from a cross section including the axis of the winding frame, the winding frame is formed Fig.10 In the configuration shown in (a), the superconducting flat wire 10 is wound in one layer spirally on the outer peripheral surface of the winding frame 60 along the approximate circumferential direction of the winding frame 60 to form a coil. Next, in the heat treatment step, when the thermoplastic welding resin is an amorphous resin, the coil is heated at a temperature not less than the glass transition temperature of the amorphous resin (preferably a temperature 30°C or more higher than the glass transition temperature) and not more than 300°C, or when the thermoplastic welding resin is a crystalline resin, the coil is heated at a temperature not less than the melting point of the crystalline resin and not more than 300°C, and the thermoplastic welding resins 2-6, 2-7, ..., 2-10 are melted and mutually welded, as shown in FIG. Fig.10 As shown in (b), a fusion resin layer 2' is formed.

[0130] As a method for forming a uniform fusion resin layer, it is preferable to wind the superconducting rectangular wire 10 while applying a certain tension in the above-mentioned winding step.

[0131] In the heat treatment step, when a phenoxy resin is used as the thermoplastic welding resin 2, the heating temperature is 100 to 300° C., preferably 130 to 250° C. If the welding treatment temperature is lower than 100° C., a long welding treatment is required, and if the welding treatment temperature exceeds 300° C., the performance of the superconducting wire may be deteriorated due to heating, which is not desirable.

[0132] Example

[0133] Next, in order to make the effects of the present invention more clear, examples and comparative examples will be described, but the present invention is not limited to these examples.

[0134] The NbTi wire whose surface is coated with copper or copper alloy, using polyamide-imide resin (Neoheat AlOOC manufactured by Dongte Paint Co., Ltd.) as the insulating resin layer, using phenoxy resin (YP-50 manufactured by Nippon Steel Chemical & Material Co., Ltd.) as the welding resin layer, was manufactured with the dimensions shown in the columns of "wire material", "insulating resin layer" and "welding resin layer" in Table 1 below. Fig.11 The superconducting flat wires of Examples 1 to 6 and Comparative Examples 1 to 6 are shown. The superconducting flat wires were wound in 20 layers on a winding frame made of SUS304 with a main body diameter of 300 mm and a width of 500 mm, and then placed in an argon atmosphere furnace and heated at 200°C for 120 minutes to obtain superconducting coils. The dimensions of the superconducting coils of Examples 1 to 6 and Comparative Examples 1 to 6 are shown in Table 1 below.

[0135] The superconducting coils of Examples 1 to 6 and Comparative Examples 1 to 6 were cooled using liquid helium, and current was repeatedly supplied multiple times until the current at the designed magnetic field was achieved (current increase rate 50 A / min). The evaluation results of the maximum magnetic field, the number of training quenches until the maximum magnetic field was achieved, and the number of repetitions of the thermal cycle (normal temperature and 4K) from the maximum magnetic field to the magnetic field reduction are shown in Table 1 below.

[0136] [Table 1]

[0137]

[0138] Regarding Examples 7 to 8 and Comparative Examples 7 to 8, superconducting coils were manufactured under the same conditions as in Examples 1 to 6 and Comparative Examples 1 to 6, except that only one layer of superconducting rectangular wire having the sizes shown in the "Wire", "Insulating resin layer" and "Fusing resin layer" columns in Table 2 below was wound around the winding frame, and the same evaluation as in Examples 1 to 6 and Comparative Examples 1 to 6 was performed.

[0139] [Table 2]

[0140]

[0141] Description of Reference Numerals

[0142] 1. 1' wire

[0143] 1'-1~1'-10、1a'-1~1a'-10、1b'-1~1b'-10 Specific parts of wire

[0144] 10, 10' superconducting flat wire

[0145] 100 Superconducting Coil

[0146] 2.2-1~2-10 Welding resin layer

[0147] 2', 2a', 2b' Thermoplastic welding resin or welding resin layer

[0148] 3a Insulating resin layer

[0149] 41~47、41b~44b、51、52 gaps

[0150] 60 Winding frame

[0151] 61 Main body of winding frame

[0152] 61a Outer circumference of the main body of the winding frame

[0153] 62, 63 Wing plate of winding frame

[0154] 71 Inner gap

[0155] 72 Outer Space

[0156] L1, L2, L1b, L2b superconducting flat wire layer

[0157] S1, S2 separation part

[0158] W1 Long side of the wire

[0159] W1' Long side of the wire covered with insulating resin

[0160] W2 Long side of superconducting flat wire

[0161] Short side of T1 cable

[0162] T1' Short side of the wire covered with insulating resin

[0163] Short side of T2 superconducting flat wire

[0164] R1 Curvature radius of the wire corner

[0165] R1' is the curvature radius of the wire covered with insulating resin.

[0166] R2 Radius of curvature of the corner of the superconducting flat wire

Claims

1. A superconducting coil, comprising: winding frame; and at least two layers of superconducting flat wire material, wherein the superconducting flat wire material including a NbTi-based or Nb3Sn-based wire material coated with copper or a copper alloy and having a substantially rectangular cross-section is spirally wound on the outer peripheral surface of the winding frame along the substantially circumferential direction of the winding frame, and the wire materials adjacent to each other in the axial direction of the winding frame are arranged in parallel in a state of being separated from each other, The superconducting coil is characterized in that At least a thermoplastic welding resin is present at a separation portion between adjacent wires in the same superconducting flat wire layer and at a separation portion between adjacent wires in two adjacent superconducting flat wire layers. When observed from a cross section including the axis of the winding frame, at least one of the voids that can be partitioned by the outer surfaces of a total of three superconducting flat wires located in the two adjacent superconducting flat wire layers and the voids that can be partitioned by the outer surfaces of a total of four superconducting flat wires is 4% or less in terms of the area ratio occupied in the at least two superconducting flat wire layers, The wire is a flat wire and the radius of curvature (R1) of the corner portion satisfies the following equations (1) and (2): 0 <R1≤R1 max …Formula (1) In formula (2), A is 0.

06.

2. The superconducting coil according to claim 1, characterized in that: When viewed from a cross section including the axis of the winding frame, the space is defined by outer surfaces of a total of three or a total of four superconducting flat wires located in the two adjacent superconducting flat wire layers and adjacent to each other.

3. A superconducting coil having: winding frame; and a superconducting flat wire layer, wherein the superconducting flat wire having a substantially rectangular cross-section and comprising a NbTi-based or Nb3Sn-based wire coated with copper or a copper alloy is spirally wound on an outer peripheral surface of the winding frame in a substantially circumferential direction of the winding frame, and the wires adjacent to each other in the axial direction of the winding frame are arranged in parallel in a state of being separated from each other, The superconducting coil is characterized in that At least a thermoplastic welding resin is present at a separation portion between adjacent wires in the superconducting flat wire layer. When observed from a cross section including the axis of the winding frame, the void fraction (V1) which is a ratio of area occupied by the voids formed by the outer surfaces of two adjacent superconducting flat wires in the superconducting flat wire layer is 4% or less, The wire is a flat wire and the radius of curvature (R1) of the corner portion satisfies the following equations (1) and (2): 0<R1≤R1 max …Formula (1) In formula (2), A is 0.

06.

4. The superconducting coil according to any one of claims 1 to 3, characterized in that: The superconducting rectangular wire has a welding resin layer formed of the thermoplastic welding resin and covering the outer peripheral surface of the wire.

5. The superconducting coil according to any one of claims 1 to 3, characterized in that: The thermoplastic welding resin includes one or more selected from the group consisting of phenoxy resins, polyamide resins, and polyester resins.

6. The superconducting coil according to claim 4, characterized in that: The said superconducting rectangular wire further has an insulating resin layer between the outer peripheral surface of the said wire and the said fusion resin layer.

7. The superconducting coil according to claim 6, characterized in that: The insulating resin layer includes one or more selected from the group consisting of polyvinyl formal resin, polyamide-imide resin, polyimide resin, polyester resin, and polyurethane resin.

8. The superconducting coil according to claim 6 or 7, characterized in that: The average coating thickness of the insulating resin layer is not less than 0.005 mm and not more than 0.100 mm.

9. The superconducting coil according to any one of claims 1 to 3, characterized in that: The wire is a flat wire and a curvature radius (R1) of a corner portion is greater than or equal to 0.1 mm and less than or equal to 0.4 mm.

10. A superconducting flat wire, which is a superconducting flat wire for a superconducting coil, wherein the superconducting flat wire for a superconducting coil has: NbTi-based or Nb3Sn-based wires whose surfaces are coated with copper or copper alloy; and a welding resin layer formed of a thermoplastic welding resin and covering the outer peripheral surface of the wire, The superconducting flat wire is characterized in that The average coating thickness of the welding resin layer is 0.005 mm or more and 0.100 mm or less. The curvature radius (R2) of the corner of the superconducting flat wire satisfies the following equations (3) and (4): 0<R2≤R2 max …Formula (3) In formula (4), B is 0.

06.

11. The superconducting flat wire according to claim 10, characterized in that: The average coating thickness of the welding resin layer is 0.01 mm or more and 0.07 mm or less.

12. The superconducting flat wire according to claim 10 or 11, characterized in that: The thermoplastic welding resin includes one or more selected from the group consisting of phenoxy resins, polyamide resins, and polyester resins.

13. The superconducting flat wire according to claim 10 or 11, characterized in that: An insulating resin layer formed of an insulating resin is further provided between the outer peripheral surface of the wire and the welding resin layer.

14. The superconducting flat wire according to claim 13, characterized in that: The insulating resin includes one or more selected from the group consisting of polyvinyl formal resin, polyamide-imide resin, polyimide resin, polyester resin, and polyurethane resin.

15. The superconducting flat wire according to claim 13, characterized in that: The average coating thickness of the insulating resin layer is not less than 0.005 mm and not more than 0.100 mm.

16. The superconducting flat wire according to claim 10 or 11, characterized in that: The wire is a flat wire and a curvature radius (R1) of a corner portion is greater than or equal to 0.1 mm and less than or equal to 0.4 mm.

17. The superconducting flat wire according to claim 10 or 11, characterized in that: The wire is a flat wire and the radius of curvature (R1) of the corner portion satisfies the following equations (1) and (2): 0<R1≤R1 max …Formula (1) In formula (2), A is 0.

06.

18. A method for manufacturing a superconducting coil, comprising the following steps: Winding process, wherein The superconducting flat wire according to any one of claims 10 to 17 is spirally wound on the outer peripheral surface of the winding frame along the substantially circumferential direction of the winding frame to form a coil having at least two layers of superconducting flat wire layers in which the wires adjacent to each other in the axial direction of the winding frame are arranged in parallel in a state of being separated from each other; and A heat treatment process, wherein, when the thermoplastic welding resin is an amorphous resin, the coil formed in the winding process is subjected to a heat treatment at a temperature above the glass transition temperature of the amorphous resin and below 300°C, or when the thermoplastic welding resin is a crystalline resin, the coil formed in the winding process is subjected to a heat treatment at a temperature above the melting point of the crystalline resin and below 300°C.

19. A method for manufacturing a superconducting coil, comprising the following steps: Winding process, wherein The superconducting flat wire according to any one of claims 10 to 17 is spirally wound on the outer peripheral surface of the winding frame along the substantially circumferential direction of the winding frame to form a coil having one superconducting flat wire layer in which wires adjacent to each other in the axial direction of the winding frame are arranged in parallel in a state of being separated from each other; and A heat treatment process, wherein, when the thermoplastic welding resin is an amorphous resin, the coil formed in the winding process is subjected to a heat treatment at a temperature above the glass transition temperature of the amorphous resin and below 300°C, or when the thermoplastic welding resin is a crystalline resin, the coil formed in the winding process is subjected to a heat treatment at a temperature above the melting point of the crystalline resin and below 300°C.

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