Superconducting coil device

Abstract

To prevent contact resistivity via an adhesive layer from becoming too low or adjust the contact resistivity at a desired value or in a desired range, even when the adhesive layer is thinned, in the case where a current bypass route of a superconducting coil is constituted by using the conductive adhesive layer.SOLUTION: A superconducting coil device comprises a superconducting coil in which a superconducting wire rod 1 is wound like a coil, and an adhesive layer 12 which constitutes at least a part of a current bypass route of the superconducting coil, which includes a binder 12a and to which conductivity is imparted. The adhesive layer 12 has a resistance drop suppression structure 12b, 12c or 12d which suppresses a drop in resistance to contact with the superconducting wire rod 1 while imparting the conductivity to the adhesive layer 12.SELECTED DRAWING: Figure 5B

Description

[Technical field]

[0001] The present invention relates to a superconducting coil device including a superconducting coil formed by winding a superconducting wire into a coil shape, and more particularly to a superconducting coil device including a current bypass path for the superconducting coil. [Background technology]

[0002] A superconducting coil device can generate a strong magnetic field by passing a large current with low loss. Such superconducting coil devices are used, for example, in NMR (nuclear magnetic resonance), MRI (magnetic resonance imaging), magnets for physical experiments, accelerators, linear trains, nuclear fusion reactors, motors, generators, silicon single crystal pulling devices, aluminum melting devices, etc.

[0003] In a superconducting coil device, the superconducting coil may suddenly or gradually transition from a superconducting state to a normal conducting state. This is called a quench. When a quench occurs, the temperature of the superconducting coil increases excessively due to Joule heat generated, which may result in damage (burnout). For this reason, in superconducting coil devices, it is important to have technology that suppresses the occurrence of quenches and protects the coils from damage if a quench does occur. This is called quench protection technology.

[0004] This type of technological system has been established for coils made of low-temperature superconductor (LTS) wire, which has already been widely put into practical use, but such technology is still immature for coils made of high-temperature superconductor (HTS) wire, the next-generation material.

[0005] In response to this situation, several techniques (such as the No-insulation method and the Metal as Insulation method) have been proposed for forming a current bypass path that electrically connects multiple turns of a high-temperature superconducting wire wound in a coil shape, and research and development is being carried out in this field. Such techniques are disclosed in, for example, Patent Document 1 and Non-Patent Document 1.

[0006] Patent Document 1 and Non-Patent Document 1 disclose the Intra-Layer No-Insulation (LNI) method invented by the inventor of the present application. That is, in Patent Document 1 and Non-Patent Document 1, when forming a solenoid coil of multiple layers arranged in the radial direction using one or multiple superconducting wires, adjacent layers are insulated from each other by an insulating sheet, and multiple turns of the solenoid coil are brought into contact with a copper sheet in each layer. Such a copper sheet forms a current bypass path that diverts the current when a quench occurs. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2021 / 172276 [Non-patent literature]

[0008] [Non-Patent Document 1] Y. Suetomi et al., “Quench and self-protecting behavior of an intra-layer no-insulation (LNI) REBCO coil at 31.4 T”, Supercond. Sci. Technol. 34 (2021) 064003 (18pp) [Non-Patent Document 2] Suetomi et al., "Design Study of intra-Layer No-Insulation (LNI) REBCO Coil for Conduction-Cooled All-HTS 900 MHz NMR Magnet," 104th Fall 2022 Cryogenics and Superconductivity Society, 2A-a01, 2022 [Non-Patent Document 3] Tanaka et al., "Development of intra-Layer No-Insulation (LNI) REBCO coil contact resistivity control technology using conductive epoxy," 104th Fall 2022 Cryogenics and Superconductivity Society, 2A-a02, 2022 Summary of the Invention [Problem to be solved by the invention]

[0009] In a superconducting coil device, the value of the contact resistivity (hereinafter simply referred to as contact resistivity) between the superconducting wire (the above-mentioned turn portion) and the current bypass path affects the occurrence of a quench and the protection of the coil when a quench occurs. For example, if the contact resistivity is too high, the temperature will rise when a quench occurs, causing thermal damage, while if the contact resistivity is too low, a large induced current will be generated locally when a quench occurs, causing mechanical damage due to electromagnetic force. This type of induced current occurs when the current in a certain turn portion decreases, and the current in a nearby turn portion that is strongly magnetically coupled increases to compensate for the decrease in magnetic flux caused by the current decrease. The contact resistivity is, for example, calculated as the resistance [Ω] between the superconducting wire and the current bypass path and the contact area (or adhesive area) [cm] between the superconducting wire and the current bypass path. 2 ] and its product [Ωcm 2 ]. The contact resistivity defined in this way is sometimes expressed as bypass resistance. In the following, the term contact resistivity is mainly used, but contact resistivity and bypass resistance are synonymous.

[0010] In order to prevent the occurrence of a quench or to protect a superconducting coil after a quench, it is desirable to adjust the contact resistivity to a desired value or range without making it too small. For example, according to recent research, in a superconducting coil for a high magnetic field, the contact resistivity is set to 10 mΩ cm. 2 or more than 100mΩcm 2 There are cases where a contact resistivity of the above level is required (see Non-Patent Documents 2 and 3). In order to effectively avoid an excessive increase in induced current in other turns caused by a current decrease in a turn due to a quench, it is also effective to take into account the strength of the magnetic coupling between the turns and set the contact resistivity to an appropriate value according to the location of the superconducting coil.

[0011] However, as described above, when the turns of the superconducting coil are directly contacted with the metal conductor of the current bypass path (for example, the copper sheet described above), the contact resistivity is, for example, 0.1 to 1 mΩ cm 2 The value becomes so low that it is difficult to adjust.

[0012] In response to this, Non-Patent Document 3 discloses the use of conductive epoxy, which is epoxy resin mixed with conductive filler, as a contact interface with a superconducting coil. Based on this disclosure, for example, it is conceivable to electrically connect multiple turns of a superconducting coil and the above-mentioned copper sheet via conductive epoxy.

[0013] However, in this case, if the thickness of the conductive epoxy is made small (for example, 30 μm or less or 20 μm or less), the superconducting wire will directly contact the copper sheet at many points. This is caused by the unevenness of the surface shape of the superconducting wire and the copper sheet, and is a phenomenon discovered by the inventors. As a result, the contact resistivity between the superconducting wire and the copper sheet via the conductive epoxy becomes too low or varies greatly, making it difficult to adjust the contact resistivity to a desired value or range. On the other hand, in order to adjust the contact resistivity to a desired value or range without making it too low, it is possible to increase the thickness of the conductive epoxy, but in this case, there is a possibility that the superconducting coil device will become large in size or that the conductive epoxy will become a factor inhibiting cooling.

[0014] Therefore, an object of the present invention is to provide a technology that, when a current bypass path is formed using a conductive adhesive layer, can prevent the contact resistivity through the adhesive layer from becoming too small even if the thickness of the adhesive layer is made thin (for example, 30 μm or less or 20 μm or less), or can adjust the contact resistivity to a desired value or range. [Means for solving the problem]

[0015] In order to achieve the above object, a superconducting coil device according to the present invention comprises: a superconducting coil formed by winding a superconducting wire into a coil shape; an adhesive layer that constitutes at least a part of a current bypass path for the superconducting coil, that contains a binder and that is provided with electrical conductivity; The adhesive layer has a resistance reduction suppression structure that imparts electrical conductivity to the adhesive layer and suppresses a reduction in contact resistance with the superconducting wire. Effect of the Invention

[0016] According to the present invention, the adhesive layer containing the binder has a resistance reduction suppression structure that imparts electrical conductivity to the adhesive layer while suppressing a decrease in contact resistance with the superconducting wire, thereby preventing the contact resistivity through the adhesive layer from becoming unintentionally too small. [Brief description of the drawings]

[0017] [Figure 1] 1 is a perspective view showing a cross section of a superconducting coil device according to a first embodiment of the present invention. [Diagram 2] 2 is an exploded explanatory view of the winding structure of the superconducting wire 1. FIG. [Diagram 3] FIG. 2 is an enlarged view of a region R1 surrounded by a dashed line in FIG. [Figure 4] 4 is a partially enlarged view of FIG. 3, showing the cross-sectional structure of the superconducting wire. [Figure 5A] FIG. 4 is a partially enlarged view of FIG. 3, and shows a schematic diagram of Configuration Example 1 of the adhesive layer. [Figure 5B] FIG. 4 is a partially enlarged view of FIG. 3, and shows a schematic diagram of a second configuration example of the adhesive layer. [Figure 6] 1 is a graph showing the contact resistivity measured for each of the adhesive layers of Examples 1 and 2 and Reference Examples 1 and 2. [Figure 7A] 13 is a graph showing the contact resistivity measured for the adhesive layer of Example 3. [Figure 7B] 13 is a graph showing the current-voltage characteristics measured for the adhesive layer of Example 3. [Figure 8] 13 is a table showing experimental results regarding insulating fillers in adhesive layers. [Figure 9A] 1 shows the transition of contact resistivity when a superconducting coil is repeatedly changed between a superconducting state and a room temperature state. [Figure 9B] 1 shows the transition of the critical current value when the superconducting coil is repeatedly changed between a superconducting state and a room temperature state. [Figure 10A] 1. FIG. 2 is an enlarged view of an area R2 surrounded by a dashed line in FIG. 1, showing the case of the second embodiment. [Figure 10B] 1. FIG. 2 is an enlarged view of an area R3 surrounded by a dashed line in FIG. 1, showing the case of the second embodiment. [Figure 11A] FIG. 2 is an enlarged view of an area R2 surrounded by a dashed line in FIG. 1, showing the case of the first embodiment. [Figure 11B]2 is an enlarged view of an area R3 surrounded by a dashed line in FIG. 1, showing the case of the first embodiment. [Figure 12] FIG. 11 is a perspective view showing a cross section of a superconducting coil device according to a third embodiment of the present invention. [Figure 13] FIG. 13 is an enlarged view of a region R4 surrounded by a dashed line in FIG. [Figure 14A] FIG. 13 is an enlarged view of a region R5 enclosed by a dashed line in FIG. [Figure 14B] 13 is an enlarged view of the region R5 surrounded by a dashed line in FIG. 12, showing another configuration example. [Figure 15] 13 is an enlarged view of the region R4 surrounded by a dashed line in FIG. 12, showing another configuration example. [Figure 16] 12. This is an enlarged view of the region R4 surrounded by the dashed line in FIG. 12, and shows yet another configuration example. [Figure 17] FIG. 13 is an enlarged view of a region R4 surrounded by a dashed line in FIG. 12, showing yet another configuration example. [Figure 18A] 1 shows an example of the cross-sectional configuration of a bundle-type superconducting wire according to Modification Example 1. [Figure 18B] 13 shows another example of the cross section of the bundle-type superconducting wire according to Modification Example 1. [Figure 19A] 1. FIG. 1 is an enlarged view of an area R1 surrounded by a dashed line in FIG. [Figure 19B] 13 is an enlarged view of an area R4 surrounded by a dashed line in FIG. 12, showing a configuration example of the second modified example. [Figure 20A] 3, and shows a schematic diagram of a configuration example of an adhesive layer according to a fifth modified example. FIG. [Figure 20B] FIG. 13 is an enlarged cross-sectional view showing another example of the configuration of the fibrous body in Modification Example 5. [Figure 20C] 5B is an enlarged view of FIG. 5A, showing a case where the fibrous body of FIG. 20B is used in the fifth modified example. [Figure 21] The measurement results of the contact resistivity (bypass resistance) when a metal mesh is used as the fibrous body are shown. [Figure 22]13 shows the transition of contact resistivity when the fibrous body of Modification Example 5 is used and the superconducting coil is repeatedly changed between a superconducting state and a room temperature state. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] [Summary of the Invention] A superconducting coil device according to one aspect of the present invention includes a superconducting coil formed by winding a superconducting wire into a coil shape, and an adhesive layer that constitutes at least a part of a current bypass path of the superconducting coil, contains a binder, and is provided with electrical conductivity. The adhesive layer has a resistance reduction suppression structure that provides electrical conductivity to the adhesive layer and suppresses a decrease in contact resistance (contact resistivity) with the superconducting wire. This resistance decrease suppression structure includes a conductive filler and an insulating filler in the first to third embodiments described below, etc. Alternatively, in the fifth modification described below, the resistance decrease suppression structure includes a fibrous body (e.g., a metal mesh) formed of conductive fibers.

[0019] The current bypass path of a superconducting coil is a path (e.g., a path for diverting the current) through which the current flows so as to avoid a certain portion of the superconducting wire forming the superconducting coil when that portion returns to a normal conductive state and generates electrical resistance. This current passes through the adhesive layer in the current bypass path from one side in the thickness direction of the adhesive layer to the other side in the thickness direction of the adhesive layer.

[0020] In one configuration, as in the first to third embodiments described later, the current bypass path is a path that electrically connects at least a plurality of different locations (hereinafter simply referred to as a plurality of locations) in the superconducting wire forming the superconducting coil. When a quench occurs in the superconducting coil and a portion between a first location and a second location included in the plurality of locations in the superconducting wire returns to a normal conductive state and generates electrical resistance, the current flows through the current bypass path from the first location to the second location instead of the portion. In the first to third embodiments described later, the plurality of locations are, for example, a plurality of turn portions in one layer (coil layer described later) of the superconducting coil, or turn portions located at the ends of two adjacent coil layers.

[0021] In another configuration, as in Modifications 1 and 2 described later, the current bypass path of the superconducting coil is such that, when any one of a plurality of locations in the superconducting wire returns to a normal conductive state due to a quench and electrical resistance occurs, the current flows through the current bypass path to another location among the plurality of locations so as to avoid the location. In Modifications 1 and 2 described later, the plurality of locations are a plurality of superconducting wires constituting a bundle-type superconducting wire.

[0022] The current bypass path may be provided in the superconducting coil. In the first to third embodiments described later, such a current bypass path is provided between adjacent coil layers that constitute the superconducting coil, and in the first and second modified examples described later, the current bypass path is provided between a plurality of superconducting wires that constitute a bundle-type superconducting wire.

[0023] According to such a superconducting coil device, the adhesive layer constituting the current bypass path further includes an insulating filler in addition to the binder and the conductive filler in the first to third embodiments described later. The insulating filler functions as a spacer in the adhesive layer. Therefore, even if the adhesive layer is formed thin, the spacer prevents the occurrence of a location where low resistance parts (for example, a turn part and a conductor part of a superconducting wire described later) on both sides in the thickness direction of the adhesive layer directly contact each other. Therefore, the adhesive layer is present in at least a part of the current bypass path, so that it is possible to prevent the contact resistivity through the adhesive layer from becoming too small. In this way, the conductive filler and the insulating filler form a resistance reduction suppression structure that imparts conductivity to the adhesive layer while suppressing a decrease in the contact resistance (contact resistivity) with the superconducting wire. The resistance reduction suppression structure in the case of the fifth modified example will be described later. The adhesive layer may be provided at one end, both ends, or in the middle of the current bypass path in the direction of current flow.

[0024] The adhesive layer may contain, as the conductive filler, a plurality of types of conductive fillers having different electrical conductivities. That is, the plurality of types of conductive fillers are formed of materials having different electrical conductivities. In this case, by adjusting the mixing ratio of the plurality of types of conductive fillers having different electrical conductivities, the contact resistivity with the superconducting wire can be adjusted to a desired value or range.

[0025] [First embodiment] 1 is a perspective view showing an example of a cross section of a superconducting coil device 10 according to a first embodiment of the present invention. This cross section is taken along an imaginary plane including a central axis C of a superconducting coil 11 provided in the superconducting coil device 10. Note that the cross section of the superconducting coil device 10 taken along any imaginary plane including the central axis C may be the same as the cross section shown in FIG.

[0026] The superconducting coil device 10 is a device that generates a magnetic field by current flowing through a superconducting coil 11, and is used, for example, in NMR, MRI, magnets for physical experiments, accelerators, linear railways, nuclear fusion reactors, motors, generators, silicon single crystal pulling devices, aluminum melting devices, etc.

[0027] <Configuration of superconducting coil> The superconducting coil 11 is formed by winding the superconducting wire 1 in a coil shape. In the first embodiment, the superconducting wire 1 is wound (e.g., spirally) around the central axis C of the superconducting coil 11 while moving in a direction parallel to the central axis C of the superconducting coil 11 (hereinafter, also simply referred to as the axial direction). Such a superconducting coil 11 may be a solenoid coil (cylindrical coil) as in the configuration example of FIG. 1, but may have another shape. The other shape may be, for example, a racetrack shape or a D-shape, but is not limited thereto.

[0028] The superconducting wire 1 may be wound around the outer peripheral surface of a reel 2 as shown in Fig. 1. The central axis of the reel 2 may coincide with the central axis C of the superconducting coil 11. The reel 2 may be cylindrical as shown in Fig. 1, but may have other shapes as long as the superconducting wire 1 can be wound in a coil shape around the outer peripheral surface of the reel. In Fig. 1, holding members 3 for holding the axial ends of the superconducting coil 11 are attached to both axial ends of the reel 2.

[0029] The outer peripheral surface of the reel 2 may be made of an electrically insulating material. If not, the superconducting wire 1 may be wound around the outer peripheral surface of the reel 2, for example, via an electrically insulating sheet-like member (not shown). The holding member 3 may be made of an electrically insulating material. In the holding member 3, a surface that contacts the axial end of the superconducting coil 11 may be made of an electrically insulating material. If not, the holding member 3 holds the axial end of the superconducting coil 11 via an electrically insulating sheet-like member (not shown). In the following, the region shown as the reel 2 in each figure will be described as being an electrically insulating portion.

[0030] 2 is an exploded explanatory view of the winding structure of superconducting wire 1. As shown in FIG. 2, a configuration in which superconducting wire 1 is wound around central axis C while moving in the axial direction is regarded as one coil layer (hereinafter simply referred to as coil layer) in the radial direction (hereinafter simply referred to as radial direction) of superconducting coil 11, and superconducting coil 11 has multiple coil layers adjacent to each other in the radial direction. FIG. 2 shows first to third coil layers of such multiple (e.g., many) coil layers separated from each other. The multiple coil layers have a common central axis C shown in FIG. 1.

[0031] The multiple coil layers are formed by superconducting wires 1. That is, in one coil layer (the innermost layer in the radial direction), the superconducting wire 1 extends around the central axis C while moving in the axial direction from one end to the other end, then moves radially outward to the next coil layer, and in the next coil layer (second layer), extends around the central axis C while moving in the axial direction from the other end to one end, then moves radially outward to the next coil layer (third layer), repeating this process. Here, the superconducting wire 1 may be one continuous superconducting wire, or may be a plurality of superconducting wires connected in series. In the latter case, the superconducting wire 1 may have a plurality of superconducting wires connected in series and a connection portion between these superconducting wires. The connection portion may be formed by solder connection, heat treatment, or the like.

[0032] In FIG. 2, each dashed arrow indicates a location where the superconducting wire 1 transitions from a radially inner coil layer to the next radially outer coil layer (hereinafter, simply referred to as a transition location). When multiple coil layers are formed by superconducting wire 1 in which multiple superconducting wires are connected in series, at each transition location, an end of the superconducting wire forming the radially inner coil layer and an end of the superconducting wire forming the radially outer coil layer may be connected to each other at a connection part formed by solder connection, heat treatment, or the like. The number of coil layers formed by the superconducting wire 1 may be two or three. In this case, the above repetition is limited to the second or third coil layer. The number of coil layers may be four or more.

[0033] FIG. 3 is an enlarged view of an area R1 enclosed by a dashed line in FIG. 1, and shows a schematic configuration of that part.

[0034] The superconducting wire 1 is configured to include a superconducting layer 1a formed of a superconducting material. This superconducting layer 1a may be a high-temperature superconducting layer 1a. Here, the "high-temperature superconducting layer 1a" may be a wire made of a superconductor material that generally has a critical temperature Tc (transition temperature) of about 25 K or higher (e.g., higher than 25 K) in the absence of a magnetic field. For example, the high-temperature superconducting layer 1a may be a wire made of a superconductor material such as an oxide superconductor including a copper-based material or an iron-based superconductor.

[0035] More specifically, the high-temperature superconducting layer 1a may be a wire made of an yttrium-based superconductor or a bismuth-based superconductor, and has the chemical formula YBa2Cu3O 7-δ or ReBa2Cu3O, in which the element Y in the formula is replaced with Re, which represents a rare earth element. 7-δ , Bi2Sr2CaCu2O 8+δ (Bi2212) and Bi2Sr2Ca2Cu3O 10+δ Bi2Sr2Ca containing (Bi2223) n-1 Cu n O 4+2n+δThe wire may be made of a yttrium-based superconductor or a bismuth-based superconductor. The wire may be used as the high-temperature superconducting layer 1a by precipitating oxide nanoparticles of zirconium, dysprosium, or the like to improve the critical current characteristics or by replacing a part of the wire with another element. The wire may be made of a metal-based superconductor such as MgB2 having a superconducting transition temperature of more than 25K.

[0036] FIG. 4 is a partially enlarged view of FIG. 3, showing the cross-sectional structure of the superconducting wire 1. The superconducting wire 1 may have a substrate layer 1b and a stabilization layer 1c in addition to the superconducting layer 1a for mechanical reinforcement and electrical stabilization. The superconducting layer 1a is laminated on the substrate layer 1b via, for example, an intermediate layer (not shown). The substrate layer 1b may be made of a metal (for example, Hastelloy). The intermediate layer may have a function of improving the crystal orientation of the superconducting layer 1a and a function of suppressing the reaction between the superconducting layer 1a and the metal substrate 1b. The stabilization layer 1c may be laminated on the superconducting layer 1a via, for example, a silver protective layer (not shown). The silver protective layer may be located on the surface of the superconducting layer 1a opposite to the intermediate layer. The stabilization layer 1c may be provided so as to cover the entire outer periphery of the substrate layer 1b and the superconducting layer 1a (and the intermediate layer and silver protective layer not shown), for example, as shown in FIG. 4. The stabilization layer 1c is made of, for example, copper.

[0037] <Configuration of current bypass path> 3, the superconducting coil device 10 includes a conductive adhesive layer 12 in contact with a plurality of turn portions T of the superconducting coil 11 in each coil layer. The adhesive layer 12 forms a current bypass path that electrically connects the plurality of turn portions T to each other.

[0038] As described later, the adhesive layer 12 contains an electrically insulating binder 12a (adhesive) and has electrical conductivity due to the conductive filler 12b being mixed in the binder 12a. A more detailed configuration of the adhesive layer 12 will be described later.

[0039] In this embodiment, the superconducting coil device 10 further includes a conductor portion 13 and an interlayer insulating portion 14 in each coil layer. That is, an adhesive layer 12, a conductor portion 13, and an interlayer insulating portion 14 are provided corresponding to each coil layer. Each of the adhesive layer 12, the conductor portion 13, and the interlayer insulating portion 14 may be formed in a layer or sheet shape having a small thickness in the radial direction. Also, in this embodiment, each of the adhesive layer 12, the conductor portion 13, and the interlayer insulating portion 14 may extend in the circumferential direction and the axial direction (hereinafter simply referred to as the circumferential direction and the axial direction, respectively) of the superconducting coil 11 along the corresponding coil layer. Each of the adhesive layer 12, the conductor portion 13, and the interlayer insulating portion 14 may extend over the entire corresponding coil layer. For example, each of the adhesive layer 12, the conductor portion 13, and the interlayer insulating portion 14 may be formed so as to go around once in the circumferential direction (for example, cylindrical). 3, between each pair of adjacent coil layers, an adhesive layer 12, a conductor portion 13, and an interlayer insulating portion 14 are provided in this order from the radially inner side to the radially outer side, although this order may be reversed.

[0040] The adhesive layer 12 also has a function of bonding the superconducting wire 1 extending around the central axis C and the conductor portion 13 in each coil layer with a binder 12a described below. The adhesive layer 12 may be in contact with all the turn portions T in the corresponding coil layer. Such an adhesive layer 12 may extend continuously in the axial and circumferential directions over almost the entire coil layer.

[0041] The conductor portion 13 is formed of a conductive material, which may be, for example, copper, platinum, gold, silver, brass, stainless steel, or other metals. The conductor portion 13 is provided so as to be electrically connected to a plurality (all) of turn portions T of the corresponding coil layer via the adhesive layer 12.

[0042] Therefore, the adhesive layer 12 corresponding to each coil layer constitutes a current bypass path that electrically connects the multiple turns of the superconducting coil 11 in that coil layer together with the conductor portion 13 corresponding to that coil layer. In this manner, a current bypass path is formed for each coil layer.

[0043] The current bypass path formed by the adhesive layer 12 and the conductor portion 13 is, for example, a path in the corresponding coil layer that runs from any of the turn portions T through the adhesive layer 12 to the conductor portion 13, proceeds axially through the conductor portion 13, and runs from the conductor portion 13 to another (e.g., adjacent) turn portion T through the adhesive layer 12, as shown by the dashed arrow in Figure 3.

[0044] The electrical conductivity of the adhesive layer 12 may be lower than the electrical conductivity of the conductor portion 13. Furthermore, the resistance per unit length of the adhesive layer 12 in a direction (e.g., axial direction) perpendicular to the thickness direction of the adhesive layer 12 may be lower than the resistance per unit length of the superconducting wire 1 in the normal conductive state (unit length in the direction in which the superconducting wire 1 extends) and higher than the resistance per unit length of the superconducting wire 1 in the superconducting state. As a result, when a quench occurs in the superconducting coil 11, the electric resistance generated in the superconducting coil 11 that has returned to the normal conductive state causes the current of the superconducting coil 11 to flow through the above-mentioned current bypass path. As a result, the superconducting coil 11 is prevented from burning out.

[0045] The interlayer insulation portion 14 corresponding to each coil layer is provided between the conductor portion 13 corresponding to that coil layer and the adjacent coil layer so that the conductor portion 13 does not come into contact with the radially adjacent coil layer (superconducting wire 1).

[0046] <Configuration of adhesive layer> Fig. 5A and Fig. 5B are partial enlarged views of Fig. 3. Fig. 5A is a diagram that typically shows a first configuration example of the adhesive layer 12, and Fig. 5B is a diagram that typically shows a second configuration example of the adhesive layer 12.

[0047] As shown in FIG. 5A or 5B, the adhesive layer 12 includes, as main components, a binder 12a, a conductive filler 12b, and an insulating filler 12c. That is, the adhesive layer 12 is a mixture of the binder 12a, the conductive filler 12b, and the insulating filler 12c. The binder 12a may be electrically insulating, but the conductive filler 12b is conductive, so that the adhesive layer 12 is conductive in the thickness direction of the adhesive layer 12 (in the first embodiment, the radial direction of the superconducting coil 11). On the other hand, according to an experiment, the adhesive layer 12 can be configured to have substantially no conductivity in a direction perpendicular to the thickness direction of the adhesive layer 12 (in the first embodiment, the axial direction and circumferential direction of the superconducting coil 11). The insulating filler 12c is electrically insulating. The insulating filler 12c may be magnesium oxide (MgO). MgO as the insulating filler 12c not only has both insulating properties and thermal conductivity, but also has a Mohs hardness of 5.5, which is not too large, so that the particles are prevented from being crushed by pressure or from being embedded in the superconducting wire 1. However, the material of the insulating filler 12c is not limited to MgO, and other materials may be used for the insulating filler 12c. The binder 12a is, for example, an epoxy resin, but is not limited thereto. The adhesive layer 12 may be composed of only the binder 12a, the conductive filler 12b, and the insulating filler 12c, or may contain components other than the above main components.

[0048] The mass ratio of the insulating filler 12c to the binder 12a may be, for example, 3% or more and less than 30%, 5% or more and 25% or less, or 5% or more and 20% or less, but is not limited to these ranges.

[0049] The average particle size of the insulating filler 12c may be larger than the average particle size of the conductive filler 12b, but is not limited to this. In this application, the average particle size may be expressed as a circle equivalent diameter by a microscopic method or a sphere equivalent diameter by a light scattering method.

[0050] The average particle diameter of the conductive filler 12b may be smaller than the thickness of the adhesive layer 12. In such a case, the average particle diameter of the conductive filler 12b may be at the same level as the thickness of the adhesive layer 12 (for example, about 2 / 3, 1 / 2 or more, 1 / 3 or more, or 1 / 5 or more of the thickness of the adhesive layer 12). Similarly, the average particle diameter of the insulating filler 12c may be smaller than the thickness of the adhesive layer 12. In such a case, the average particle diameter of the insulating filler 12c may be at the same level as the thickness of the adhesive layer 12 (for example, about 2 / 3, 1 / 2 or more, 1 / 3 or more, or 1 / 5 or more of the thickness of the adhesive layer 12). For example, the thickness of the adhesive layer 12 may be 30 μm or less. The lower limit of the thickness of the adhesive layer 12 is a thickness that can prevent the conductor portion 13 and the turn portion T (i.e., the superconducting wire 1) from directly contacting each other and causing a short circuit. For example, the lower limit of the thickness of the adhesive layer 12 is, for example, about 20 μm (18 μm as one example), but is not limited to this value and may be changed as appropriate.

[0051] Furthermore, for example, the average particle diameter of the conductive filler 12b and the average particle diameter of the insulating filler 12c may each be in the range of 5 μm or more and 25 μm or less, in the range of 10 μm or more and 20 μm or less, or in the range of 15 μm or more and 20 μm or less, but are not limited to these ranges.

[0052] In this embodiment, the conductive filler 12b and the insulating filler 12c are in a powder form. However, in the first, second, or third embodiment, a fibrous conductive filler may be used instead of the powdered conductive filler 12b. Similarly, in the first, second, or third embodiment, a fibrous insulating filler may be used instead of the powdered insulating filler 12c.

[0053] Configuration example 1 5A, in configuration example 1, the conductive filler 12b mixed in the adhesive layer 12 is of one type. That is, as the conductive filler 12b mixed in the adhesive layer 12, only conductive fillers 12b of the same conductive material (e.g., copper) are present.

[0054] Configuration example 2 As shown in Fig. 5B, in configuration example 2, there are multiple types of conductive fillers 12b mixed in the adhesive layer 12. That is, there are multiple types of conductive fillers with different conductivities as the conductive fillers 12b mixed in the adhesive layer 12. In the example of Fig. 5B, a first type of conductive filler 12b1 and a second type of conductive filler 12b2 are mixed in the adhesive layer 12 as such multiple types of conductive fillers 12b.

[0055] In one example, the first type of conductive filler 12b1 is made of copper (Cu), and the second type of conductive filler 12b2 is made of graphite (C). The number of the above-mentioned multiple types of conductive filler 12b mixed in the adhesive layer 12 is not limited to two, and may be three or more.

[0056] <Configuration regarding insulation between adjacent turn parts> The superconducting coil device 10 includes an inter-turn insulation portion 15 provided between each pair of axially adjacent turn portions T in each coil layer to prevent the turn portions T from coming into contact with each other in the axial direction. The inter-turn insulation portion 15 is formed of an electrically insulating material.

[0057] The inter-turn insulation 15 has a linear shape extending around the central axis C along the superconducting wire 1. That is, the inter-turn insulation 15 may have a shape wound around the central axis C while moving in the axial direction along the superconducting wire 1. More specifically, the inter-turn insulation 15 may extend around the central axis C along the superconducting wire 1 over the entire longitudinal direction of the superconducting wire 1 (the entire direction in which the superconducting wire 1 extends around the central axis C) while being in contact with the superconducting wire 1 in the axial direction. Such an inter-turn insulation 15 may be a linear member extending around the central axis C. For example, the inter-turn insulation 15 may be a linear member in which the entire outer periphery of a copper wire is covered with an electrically insulating material.

[0058] <Effects of the first embodiment> According to the first embodiment, the following advantages (1) to (6) are obtained.

[0059] (1) According to the superconducting coil device 10 of the present embodiment, the current bypass path is formed by the adhesive layer 12 that includes not only the binder 12a and the conductive filler 12b but also the insulating filler 12c. The insulating filler 12c functions as a spacer in the adhesive layer 12. That is, the spacer prevents the conductor portion 13 from directly contacting (short-circuiting) the superconducting wire 1. Therefore, even if the thickness of the adhesive layer 12 is reduced, it is possible to prevent the contact resistivity between the turn portion T of the superconducting coil 11 and the current bypass path (adhesive layer 12) from becoming too small, and for example, the contact resistivity can be made relatively large.

[0060] (2) In the above configuration example 2, the conductivity of the adhesive layer 12 can be adjusted to a desired value or range by adjusting the mixing ratio of the multiple types of conductive fillers 12b1, 12b2 having different conductivities. That is, for example, as in Example 3 described later, by changing the mass ratio of the multiple types of conductive fillers 12b1, 12b2 having different conductivities, the contact resistivity can be changed according to the change. This allows the conductivity of the adhesive layer 12 to be adjusted to a desired value or range.

[0061] (3) The conductor portion 13 extends in the axial direction so as to be adjacent to the multiple turn portions T aligned in the axial direction, and is electrically connected to the multiple turn portions T via the adhesive layer 12. Such adhesive layer 12 and conductor portion 13 can form a current bypass path having the above-mentioned effects (1) and (2).

[0062] (4) The inter-turn insulation 15 is provided between each pair of axially adjacent turn portions T to prevent the turn portions T from coming into contact with each other in the axial direction. This allows the current bypass path formed by the adhesive layer 12 and the conductor portion 13 to function properly. For example, even if the contact resistivity of the current bypass path with respect to the turn portion T is set high, it is possible to allow a current to flow from the turn portion T to the current bypass path when a quench occurs.

[0063] (5) With respect to each coil layer, the adhesive layer 12 extends in the axial and circumferential directions so as to contact the outer peripheral surfaces of the multiple (all) turn portions T of the superconducting wire 1 forming the coil layer, and the conductor portion 13 extends in the axial and circumferential directions so as to contact the outer peripheral surface (the entire outer peripheral surface) of the adhesive layer 12. Therefore, the cooling of the superconducting wire 1 can be promoted by heat transfer from the superconducting wire 1 to the conductor portion 13 via the adhesive layer 12. In this regard, the adhesive layer 12 can transfer the heat of the superconducting wire 1 to the conductor portion 13 mainly by the conductive filler 12b and the insulating filler 12c of the adhesive layer 12. In this regard, for example, MgO as the insulating filler 12c has a relatively high thermal conductivity.

[0064] (6) The adhesive layer 12 containing the conductive filler 12b and the insulating filler 12c mechanically bonds and integrates the multiple (all) turns of the superconducting wire 1 in each coil layer. This makes it possible to robustly maintain the superconducting coil structure against the strong electromagnetic force that is generated when a magnetic field is generated by passing a current through the superconducting coil 11, and to prevent damage and deterioration of characteristics caused by collapse, buckling, peeling, etc. of the superconducting wire 1.

[0065] (Examples 1 and 2: When there is one type of conductive filler) In each of Examples 1 and 2 and Reference Examples 1 and 2, an adhesive layer was formed, and the contact resistivity of the adhesive layer with respect to the superconducting wire was measured.

[0066] The first and second embodiments correspond to the above-mentioned configuration example 1. The adhesive layer 12 of Example 1 is a mixture of epoxy resin binder 12a, graphite powder as conductive filler 12b, and magnesium oxide (MgO) powder as insulating filler 12c. In Example 1, the content of MgO in the entire adhesive layer 12 is 5 wt%. The adhesive layer 12 of Example 2 is a mixture of an epoxy resin binder 12a, copper powder as conductive filler 12b, and magnesium oxide (MgO) powder as insulating filler 12c. In Example 2, the content of MgO in the adhesive layer 12 is also 5 wt%.

[0067] Reference Examples 1 and 2 correspond to the cases where the adhesive layer was formed without using an insulating filler. The adhesive layer of Reference Example 1 was made by mixing graphite powder as a conductive filler into an epoxy resin binder. The adhesive layer of Reference Example 2 was made by mixing copper powder as a conductive filler into an epoxy resin binder.

[0068] The contact resistivity with the superconducting wire was measured for each of the adhesive layers in Examples 1 and 2 and Reference Examples 1 and 2. Specifically, the measurement was performed as follows. An adhesive layer 12 was disposed between two tape-shaped superconducting wires so as to be in contact with these superconducting wires. A voltage V was applied between these two superconducting wires 1, causing a current to flow from one superconducting wire through the adhesive layer to the other superconducting wire, and the value of this current was measured. From the applied voltage V, the measured value I of the current, and the known contact area A between the superconducting wire and the adhesive layer, the contact resistivity ρ ct That is, ρ ct = (V / I) × A, contact resistivity ρ ct asked for.

[0069] FIG. 6 shows the contact resistivity ρ ct 6 is a graph showing the results of the measurement of the contact resistivity (mΩcm). In FIG. 6, a number of black circle plots indicate the case of Example 1, a number of white circle plots indicate the case of Example 2, a number of black square plots indicate the case of Reference Example 1, and a white square plot indicates the case of Reference Example 2. In FIG. 6, the horizontal axis indicates the content of the conductive filler (the combined conductive filler 12b and insulating filler 12c in the cases of Examples 1 and 2) relative to the entire adhesive layer. In FIG. 6, the vertical axis indicates the measured value of the contact resistivity (mΩcm). 2) is shown.

[0070] In the case of Reference Example 1, the contact resistivity is 100 mΩcm 2 The value was around 100mΩcm. 2 That is, even if the content of the conductive filler 12b (graphite powder) was changed, the contact resistivity did not change much. Furthermore, the variation in the value of the contact resistivity was relatively large.

[0071] In the case of Reference Example 2, the contact resistivity was 10 -1 mΩcm 2 The contact resistivity was a relatively low value, and even if the content of the conductive filler 12b (copper powder) was changed, the contact resistivity did not change very much.

[0072] In contrast, in this Example 1, even if the thickness of the adhesive layer 12 was made thinner than in Reference Examples 1 and 2, by further adding insulating filler 12c to the adhesive layer 12, the contact resistivity could be made significantly higher than in Reference Examples 1 and 2. That is, when the thickness of the adhesive layer 12 was made thinner, in Reference Examples 1 and 2, the contact resistivity could not be substantially increased even if the content of the conductive filler 12b was reduced, but in Examples 1 and 2, the contact resistivity could be increased by further adding insulating filler 12c.

[0073] In this way, even when the thickness of the adhesive layer 12 is reduced, by further adding the insulating filler 12c, it is possible to make the contact resistivity of the adhesive layer 12 much larger than when the insulating filler 12c is not used, as shown in Fig. 6. For example, in the case of Example 1, the contact resistivity is reliably 100 mΩcm without being made too small. 2 or more than 1000mΩcm 2 It can be more than that.

[0074] (Example 3: When there are two types of conductive filler) In Example 3, an adhesive layer 12 was formed containing two types of conductive fillers 12b1, 12b2 having different electrical conductivities, and the contact resistivity of the adhesive layer 12 with the superconducting wire 1 was measured while changing the ratio between the two types of conductive fillers 12b1, 12b2.

[0075] The third embodiment corresponds to the above-mentioned configuration example 2. The adhesive layer 12 of Example 3 is a mixture of an epoxy resin binder 12a, graphite powder and copper powder as two types of conductive fillers 12b1 and 12b2, and magnesium oxide (MgO) powder as insulating filler 12c. In Example 3, the content of MgO in the entire adhesive layer 12 is 10 wt%, and the combined content of the two types of conductive fillers 12b1 and 12b2 in the entire adhesive layer 12 is 30 wt%.

[0076] In Example 3, the content of MgO in the entire adhesive layer 12 was fixed at 10 wt%, the content of the two types of conductive fillers 12b1 and 12b2 in the entire adhesive layer 12 was fixed at 30 wt%, and the mass ratio between the two types of conductive fillers 12b1 and 12b2 was changed to form adhesive layers 12 with each mass ratio, and the contact resistivity of each adhesive layer 12 thus formed was measured. The method for measuring the contact resistivity was the same as in Examples 1 and 2.

[0077] FIG. 7A shows the contact resistivity ρ ct 7A is a graph showing the relationship between the mass of the copper powder and the graphite powder in the adhesive layer 12 and the total mass of the graphite powder and the copper powder in the two types of conductive fillers 12b1 and 12b2. Therefore, on the horizontal axis of FIG. 7A, 0% indicates a case where no copper powder is present in the adhesive layer 12 (when the graphite content is 30%), and 100% indicates a case where no graphite powder is present in the adhesive layer 12 (when the copper content is 30%).

[0078] In FIG. 7A, the contact resistivity gradually increases by gradually decreasing the mass ratio of copper powder to graphite powder. In this manner, as shown in FIG. 7A, the conductivity of the adhesive layer 12 can be adjusted to a desired value or range by adjusting the mixing ratio (mass ratio) of the conductive fillers 12b1, 12b2 (graphite powder and copper powder) having different conductivities. In this embodiment, copper powder and graphite powder are selected as the conductive fillers 12b1, 12b2, but the conductive fillers are not limited to these materials, and powders of three or more materials may be used. This allows the contact resistivity to be within the range obtained in this embodiment.

[0079] Fig. 7B shows the current-voltage characteristics of one sample (adhesive layer 12 in which the mass ratio of copper powder in the entire conductive filler is 5%) in Example 3 of the data shown in Fig. 7A. In Fig. 7B, the horizontal axis shows the current flowing through adhesive layer 12 in its thickness direction, and the vertical axis shows the voltage applied to adhesive layer 12 in its thickness direction.

[0080] As shown in Fig. 7B, the voltage is generated linearly with respect to the current, and a simple resistive behavior is obtained. This behavior is an important characteristic from the viewpoint of protection against quenching of the superconducting coil and its design. For example, the linear current-voltage characteristic of the adhesive layer 12 prevents an excessive rise in induced current when a quench occurs, unlike the following case, and it is not necessary to consider a complex current-voltage characteristic in the design of the superconducting coil. In superconducting coils using the well-known No-insulation method, Metal as Insulation method, or the intra-layer No-insulation method, which does not have an adhesive layer as in this embodiment, a current bypass path is formed through the interface between the turn parts or the direct contact between the turn part and the conductor layer. At such interfaces, a film of copper oxide or the like is formed on the surface of the turn part or the surface of the conductor layer. This type of film has a nonlinear current-voltage characteristic regardless of its thickness, and when the current increases, the voltage increase saturates or decreases, and also shows hysteresis. If the current bypass path has such characteristics, an excessive increase in induced current occurs when a quench occurs. In addition, it is difficult to take such complicated current-voltage characteristics into consideration in the design of a superconducting coil.

[0081] (Experimental Example 1: Function of insulating filler) An adhesive layer was formed by mixing only magnesium oxide (MgO) powder as insulating filler (12c) with epoxy resin binder (12a), and while changing the content of MgO powder, the contact resistivity of the adhesive layer with superconducting wire (1) was measured in the same manner as in Examples 1 and 2. That is, the contact resistivity was measured in a state where the adhesive layer was sandwiched between two superconducting wires.

[0082] In this measurement method, it was confirmed from the measured contact resistance whether the two superconducting wires sandwiching the adhesive layer were in direct contact (short circuit) with each other, that is, whether the MgO powder in the adhesive layer had the function as the spacer described above.

[0083] In addition, when the adhesive layer is formed as thin as possible, the thickness of the adhesive layer depends on the content of the insulating filler 12c. That is, the larger the content of the insulating filler 12c, the larger the possible minimum thickness of the adhesive layer. Therefore, in this experimental example, the thickness of the adhesive layer formed as thin as possible was measured for each content of the MgO powder.

[0084] FIG. 8 is a table showing such experimental results. The first column in the table in FIG. 8 shows the content of the above-mentioned MgO powder. This content shows the mass ratio of the MgO powder to the entire adhesive layer including the binder 12a and the MgO powder. The second column in the table in FIG. 8 shows the presence or absence of a short circuit between the two superconducting wires 1 sandwiching the above-mentioned adhesive layer 12 (i.e., the presence or absence of the function of the MgO powder as a spacer). The third column in the table in FIG. 8 shows the thickness of the adhesive layer when it is formed as thin as possible as described above.

[0085] 8, when the content of insulating filler 12c was 5 wt% or more, no short circuit occurred. Also, when the content of insulating filler 12c was less than 30 wt%, the thickness of adhesive layer 12 could be reduced to 30 μm or less.

[0086] From these results, in the adhesive layer 12 of this embodiment, the mass ratio of the insulating filler 12c to the combined mass of the binder 12a and the insulating filler 12c is, for example, 3 wt% or more, 4 wt% or more, or 5 wt% or more in order to avoid a short circuit between the superconducting wire 1 and the conductor portion 13. Also, in the adhesive layer 12 of this embodiment, in order to reduce the thickness of the adhesive layer 12, the mass ratio of the combined mass of the conductive filler 12b and the insulating filler 12c to the entire adhesive layer 12 may be, for example, less than 30 wt%, 25 wt% or less, or 20 wt% or less.

[0087] (Experimental Example 2) The superconducting coil device 10 of the configuration example 2 in the above-mentioned embodiment was actually manufactured, and the superconducting coil 11 was placed in liquid nitrogen to be in a superconducting state, and in this state, the contact resistivity of the current bypass path for the turn portion T of the superconducting coil 11 was measured, and the critical current value of the superconducting coil 11 was measured. Thereafter, the superconducting coil 11 was taken out of the liquid nitrogen to be in a normal conducting state, and was again placed in liquid nitrogen to be in a superconducting state, and in this state, the contact resistivity was measured in the same manner, and the critical current value of the superconducting coil 11 was measured. Such a cooling cycle was repeated.

[0088] 9A and 9B are graphs showing the contact resistivity and the critical current value measured for each of these cycles, respectively. As shown in FIG. 9A, the contact resistivity (bypass resistance) did not fluctuate significantly and was maintained at an almost stable value even when the cooling cycle was repeated. Moreover, as shown in FIG. 9B, the critical current value remained stable and constant even when the cooling cycle was repeated. Thus, it was confirmed that in the superconducting coil 11 of this embodiment, the contact resistivity and the critical current value were stably maintained constant even when the cooling cycle was repeated.

[0089] [Second embodiment] A superconducting coil device 10 according to a second embodiment of the present invention will be described below. In the second embodiment, matters not described below may be the same as those in the first embodiment. For example, the superconducting coil 11 may be a solenoid coil (cylindrical coil) as described above, but may have other shapes such as a racetrack shape or a D-shape.

[0090] <Configuration of superconducting coil device> Figures 10A and 10B are enlarged views of regions R2 and R3 enclosed by dashed lines in Figure 1, respectively, for the second embodiment, while Figures 11A and 11B are enlarged views of regions R2 and R3 enclosed by dashed lines in Figure 1, respectively, for the first embodiment.

[0091] In the following, an inner coil layer and an outer coil layer refer to a particular pair of radially adjacent coil layers, although the following regarding the inner coil layer and the outer coil layer applies to any pair of adjacent coil layers.

[0092] The inner coil layer is the second coil layer from the inside in the radial direction in Fig. 10A and Fig. 11A, and is the first coil layer from the inside in the radial direction in Fig. 10B and Fig. 11B. As shown in each of Fig. 10A to Fig. 11B, superconducting wire 1 extends around central axis C while moving axially from one axial end (the lower end in Fig. 10A, and the upper end in Fig. 10B) to the other axial end to form an inner coil layer, then moves radially outward from the inner coil layer, and extends around central axis C while moving axially from the other axial end to one axial end to form an outer coil layer.

[0093] 10A to 11B, Te indicates a plurality of (two in the examples of these figures) turn portions T located at the other axial end of the inner coil layer, and Ts indicates a plurality of (two in the examples of these figures) turn portions T located at the other axial end of the outer coil layer.

[0094] 11A and 11B, there is no interlayer current bypass path from the turn portion Te located at the other axial end of the inner coil layer to the turn portion Ts located at the other axial end of the outer coil layer. In this case, if a quench occurs in the superconducting wire 1 near a portion where the superconducting wire 1 transitions from the inner coil layer to the outer coil layer, the superconducting wire 1 may be burned.

[0095] Taking this into consideration, in the second embodiment, as shown in Figures 10A and 10B, an interlayer current bypass path is configured to electrically connect one or more (two in Figures 10A and 10B) turn portions Te located at the other axial end of the inner coil layer and one or more (two in Figures 10A and 10B) turn portions Ts located at the other axial end of the outer coil layer.

[0096] This interlayer current bypass path is composed of a part of the adhesive layer 12, a part of the conductor portion 13, and the interlayer conductor portion 16. The part of the adhesive layer 12 and the part of the conductor portion 13 are sandwiched in the radial direction between the other axial end portion of the inner coil layer and the other axial end portion of the outer coil layer. The interlayer conductor portion 16 electrically connects the part of the conductor portion 13 and the other axial end portion of the outer coil layer.

[0097] More specifically, the interlayer conductor portion 16 contacts the part of the conductor portion 13 from the radially outer side, and contacts one or more (two in Figs. 10A and 10B) turn portions Ts located at the other axial end of the outer coil layer from the radially inner side. The interlayer conductor portion 16 may be formed in a sheet shape having a thin radial thickness. The interlayer conductor portion 16 may extend in the circumferential and axial directions along the conductor portion 13 and one or more turn portions Ts that contact it in the radial direction. For example, the interlayer conductor portion 16 may be formed in a shape that goes around once in the circumferential direction (e.g., cylindrical). The interlayer conductor portion 16 may be formed integrally with the conductor portion 13.

[0098] The above-mentioned interlayer current bypass path is, for example, a path that runs radially from the turn portion Te at the other axial end of the inner coil layer, via the adhesive layer 12, the conductor portion 13, and the interlayer conductor portion 16, to the turn portion Ts at the other axial end of the outer coil layer, as shown by the dashed arrows in Figures 10A and 10B.

[0099] Thus, the superconducting coil device 10 according to the second embodiment includes the above-mentioned interlayer conductor portion 16. This interlayer conductor portion 16 is provided in place of a portion of the interlayer insulating portion 14 that is sandwiched in the radial direction between the other axial end portion of the inner coil layer and the other axial end portion of the outer coil layer in the first embodiment. That is, in the second embodiment, this portion of the interlayer insulating portion 14 is omitted, and the interlayer conductor portion 16 is provided in the region of the omitted portion.

[0100] <Effects of the second embodiment> In addition to the above-mentioned effects (1) to (6) in the first embodiment, the following effect can be obtained. In superconducting coil 11, an interlayer current bypass path is also formed for turn portions Te, Ts at the portion (the other axial end portion) where superconducting wire 1 turns back between the inner coil layer and the outer coil layer. Therefore, burn damage due to quenching can also be prevented at the other axial end portion of the inner coil layer.

[0101] [Third embodiment] A superconducting coil device 10 according to a third embodiment of the present invention will be described below. In the third embodiment, matters that are not described below may be the same as those in the first embodiment.

[0102] <Configuration of superconducting coil device> Fig. 12 is a perspective view showing a cross section of a superconducting coil device 10 according to a third embodiment of the present invention. This cross section is taken along an imaginary plane including the central axis C of the superconducting coil 11. Unless otherwise specified below, the cross section of the superconducting coil device 10 taken along any imaginary plane including the central axis C may be the same as that shown in Fig. 12. The superconducting coil 11 may be a solenoid coil (cylindrical coil) as in the configuration example of Fig. 12, or may have another shape such as a racetrack shape or a D-shape.

[0103] Fig. 13 is an enlarged view of region R4 surrounded by a dashed line in Fig. 12. Figs. 14A and 14B are both enlarged views of region R5 surrounded by a dashed line in Fig. 12, but show different configuration examples. In Figs. 14A and 14B, the dashed arrows indicate the order in which current passes through multiple turn portions T while flowing in the circumferential direction.

[0104] <Configuration of superconducting coil> In the third embodiment, the superconducting coil 11 in which the superconducting wire 1 is wound in a coil shape is a so-called pancake coil. That is, in the third embodiment, as shown in Figs. 12 to 14B, the superconducting wire 1 is wound around the central axis C of the superconducting coil 11 multiple times (for example, many times) while the axial position parallel to the central axis C of the superconducting coil 11 remains constant. That is, the superconducting wire 1 extends from the innermost position in the radial direction to the outermost position in the radial direction while the axial position remains constant, so as to move radially outward as it goes around the central axis C. Here, the superconducting wire 1 may be one continuous superconducting wire, or may be a plurality of superconducting wires connected in series. In the latter case, the superconducting wire 1 may have a plurality of superconducting wires connected in series and a connection part between these superconducting wires. The connection part may be formed by solder connection, heat treatment, or the like.

[0105] In the third embodiment, as shown in Figures 12 to 14B, a configuration in which superconducting wire 1 extends from an inner radial end to an outer radial end while keeping the axial position constant, around central axis C, is defined as one coil layer in the axial direction (hereinafter simply referred to as a coil layer).

[0106] According to the third embodiment, superconducting coil 11 may be configured with one coil layer, or may be configured with a plurality of (for example, a large number of) coil layers stacked in the axial direction as shown in FIG.

[0107] For example, multiple coil layers may be formed from superconducting wire 1 as follows.

[0108] For each pair of coil layers that are continuous with each other on the radial inside and adjacent to each other in the axial direction, in one example, the superconducting wire 1 extends continuously from a position (a circumferential position different from the cross section shown in these figures) that constitutes the innermost turn portion T in one coil layer (the left side of these figures) as shown in Fig. 13, Fig. 14A, or Fig. 14B, while continuing to extend circumferentially, moves radially inward and axially toward the other coil layer to constitute an inner interlayer turn portion Ta (see Fig. 13, Fig. 14A, or Fig. 14B), and then extends continuously circumferentially outward and moves axially toward the other coil layer to constitute the innermost turn portion T in the other coil layer (the turn portion T at a circumferential position different from the cross section in Fig. 13). Here, the superconducting wire 1 may be one continuous superconducting wire as described above, or may be a plurality of superconducting wires connected in series (the same applies below).

[0109] For each pair of coil layers that are continuous with each other radially outward and adjacent to each other in the axial direction, as shown in Figure 14A, at the transition point between the coil layers, an end of the superconducting wire 1 forming one coil layer and an end of the superconducting wire 1 forming the other coil layer may be connected to each other via a connection part 18 formed by solder connection, heat treatment, or the like.

[0110] In another example, for each pair of coil layers that are continuous with each other radially outward and adjacent in the axial direction, as shown in Figure 14B, the superconducting wire 1 extends continuously circumferentially from a position (a circumferential position different from the cross-sections shown in these figures) that constitutes the superconducting wire 1 of the outermost turn portion T in one coil layer, while transitioning radially outward and axially toward the other coil layer, to form an outer interlayer turn portion Tb (see Figure 14B), and then extends continuously circumferentially inward and transitions axially toward the other coil layer, to form the outermost turn portion T in the other coil layer.

[0111] As shown in FIG. 14B, the inner interlayer turn portions Ta and the outer interlayer turn portions Tb may be provided alternately in the axial direction.

[0112] <Configuration of current bypass path> The superconducting coil device 10 according to the third embodiment includes a conductive adhesive layer 12 that contacts multiple (e.g., all) turn portions T of a superconducting coil 11 in one coil layer. The adhesive layer 12 forms a current bypass path that electrically connects the multiple turn portions T together in one coil layer. The configuration of this adhesive layer 12 may be the same as that of the adhesive layer 12 in the first embodiment (e.g., the adhesive layer 12 in the above-mentioned configuration example 1 or configuration example 2).

[0113] The superconducting coil device 10 according to the third embodiment includes adhesive layers 12 and conductor portions 13 provided corresponding to each coil layer.

[0114] 13 to 14B, the adhesive layer 12 and the conductor portion 13 are provided on both one axial side and the other axial side of the coil layer. A configuration consisting of such a coil layer and the adhesive layer 12 and the conductor portion 13 provided on each axial side of the coil layer may be stacked in the axial direction via an interlayer insulating portion 14. In the following, the adhesive layer 12 and the conductor portion 13 provided on one axial side of the coil layer will be described, but each feature (such as the configuration, arrangement, function, etc.) of the adhesive layer 12 and the conductor portion 13 provided on the other axial side of the coil layer is the same as each feature of the adhesive layer 12 and the conductor portion 13 provided on the one axial side.

[0115] In the third embodiment, an adhesive layer 12 and a conductor portion 13 are provided corresponding to each coil layer. The adhesive layer 12 and the conductor portion 13 may be formed in a layer or sheet shape having a small thickness in the axial direction. Such adhesive layer 12 and conductor portion 13 may extend in the circumferential and radial directions along the coil layer axially adjacent to the adhesive layer 12 and the conductor portion 13. Each of such adhesive layer 12 and conductor portion 13 may extend continuously in the circumferential and radial directions throughout the entire corresponding coil layer.

[0116] Moreover, adhesive layer 12 corresponding to each coil layer also has a function of bonding superconducting wire 1 repeatedly wound around central axis C to conductor portion 13 in that coil layer.

[0117] The adhesive layer 12 corresponding to each coil layer constitutes a current bypass path that electrically connects the multiple turns of the superconducting coil 11 in that coil layer together with the conductor portion 13 corresponding to that coil. In this manner, a current bypass path is formed for each coil layer.

[0118] A current bypass path formed by the adhesive layer 12 and the conductor portion 13 is, for example, a path in the corresponding coil layer that runs from any of the turn portions T through the adhesive layer 12 to the conductor portion 13, proceeds radially through the conductor portion 13, and runs from the conductor portion 13 to another (e.g., adjacent) turn portion T through the adhesive layer 12, as shown by the dashed arrow in Figure 13.

[0119] The interlayer insulation 14 is provided between each pair of coil layers adjacent to each other in the axial direction, and electrically insulates the coil layers from each other. For each pair of coil layers, the interlayer insulation 14 is provided between one coil layer or its current bypass path (i.e., the conductor 13) and the other coil layer of the pair or its current bypass path. In this configuration, the interlayer insulation 14 prevents the conductor 13 corresponding to each coil layer from contacting the coil layer (superconducting wire 1) adjacent to the coil layer.

[0120] Other configurations of the conductor portion 13 and the interlayer insulating portion 14 may be the same as those of the conductor portion 13 and the interlayer insulating portion 14 in the first embodiment.

[0121] <Configuration regarding insulation between adjacent turn parts> 13, the superconducting coil device 10 includes inter-turn insulation parts 15 that are provided between each pair of radially adjacent turn parts T in each coil layer and prevent the turn parts T from contacting each other in the radial direction. The inter-turn insulation parts 15 are made of an electrically insulating material.

[0122] The inter-turn insulation 15 has a linear (e.g., tape-like) shape extending around the central axis C along the superconducting wire 1. That is, the inter-turn insulation 15 may have a shape wound around the central axis C while moving in the radial direction of the superconducting coil 11 along the superconducting wire 1. More specifically, the inter-turn insulation 15 may extend around the central axis C along the superconducting wire 1 over the entire longitudinal direction of the superconducting wire 1 (the entire direction in which the superconducting wire 1 extends around the central axis C) while contacting the superconducting wire 1 in the radial direction.

[0123] <Interlayer current bypass path> As shown in Figures 13 to 14B, for each pair of coil layers that are continuous with each other radially inward and adjacent in the axial direction, an interlayer current bypass path may be configured to electrically connect the radially innermost turn portion T in one coil layer to the radially innermost turn portion T in the other coil layer.

[0124] Such an interlayer current bypass path is formed by the interlayer conductor portion 16. For each pair of coil layers, the interlayer conductor portion 16 may extend in the axial and circumferential directions so as to contact both the radially innermost turn portion T in one coil layer and the radially innermost turn portion T in the other coil layer. In this regard, the radially innermost turn portion T in one coil layer and the radially innermost turn portion T in the other coil layer may be connected via an adhesive layer (not shown) having the same configuration as the adhesive layer 12. The thickness direction of the adhesive layer is the radial direction of the superconducting coil 11.

[0125] Similarly, as shown in FIG. 14B, for each pair of coil layers that are continuous with each other radially outward and adjacent in the axial direction, an interlayer current bypass path may be configured that electrically connects the radially outermost turn portion T in one coil layer with the radially outermost turn portion T in the other coil layer.

[0126] Such an interlayer current bypass path is formed by the interlayer conductor portion 16. For each pair of coil layers, the interlayer conductor portion 16 may extend in the axial and circumferential directions so as to contact both the radially outermost turn portion T in one coil layer and the radially outermost turn portion T in the other coil layer. In this regard, the radially outermost turn portion T in one coil layer and the radially outermost turn portion T in the other coil layer may be connected via an adhesive layer (not shown) having the same configuration as the adhesive layer 12. The thickness direction of the adhesive layer is the radial direction of the superconducting coil 11.

[0127] Furthermore, for each pair of coil layers, the interlayer conductor portion 16 may be arranged to contact the radial inner end face or radial outer end face of the adhesive layer 12 and conductor portion 13 corresponding to one coil layer, and the radial inner end face or radial outer end face of the adhesive layer 12 and conductor portion 13 corresponding to the other coil layer, as shown in Figure 13, Figure 14A, or Figure 14B.

[0128] Furthermore, for each pair of coil layers, the interlayer conductor portion 16 may be provided so as to contact the interlayer turn portion (interlayer turn portion Ta in FIG. 13 and interlayer turn portion Tb in FIG. 14B) located between the coil layers. In this regard, the interlayer conductor portion 16 may be connected to the interlayer turn portions Ta, Tb located between the coil layers via an adhesive layer (not shown) having the same configuration as the adhesive layer 12. The thickness direction of the adhesive layer is the radial direction of the superconducting coil 11.

[0129] <Another configuration example> Fig. 15 is an enlarged view of region R4 surrounded by a dashed line in Fig. 12, showing another configuration example of the third embodiment. In the configuration example of Fig. 15, for each coil layer, the adhesive layer 12 and the conductor portion 13 are provided only on one axial side or the other axial side of the coil layer. Other matters regarding the configuration example of Fig. 15 may be the same as those in the configuration examples of Fig. 13, Fig. 14A, or Fig. 14B, and therefore description thereof will be omitted.

[0130] <Another example configuration> Fig. 16 is an enlarged view of region R4 surrounded by a dashed line in Fig. 12, showing yet another configuration example of the third embodiment. In the configuration example of Fig. 16, a double pancake coil is formed by a pair of coil layers adjacent to each other in the axial direction.

[0131] A pair of coil layers constituting the double pancake coil are electrically insulated from each other by providing an interlayer insulating portion 17 between them in the axial direction.

[0132] In addition, for a pair of coil layers constituting a double pancake coil, the adhesive layer 12 and the conductor portion 13 of each coil layer are provided on the opposite side to the other coil layer.

[0133] For a pair of coil layers constituting a double pancake coil, an inner or outer interlayer turn portion (the inner interlayer turn portion Ta in FIG. 16) may be provided between the coil layers, and an interlayer conductor portion 16 similar to that described above may be provided.

[0134] Such a double pancake coil and a configuration consisting of adhesive layers 12 and conductor portions 13 on each axial side of the coil may be stacked in the axial direction via interlayer insulation portions 14. A plurality or a large number of double pancake coils stacked in this manner may be formed from superconducting wire 1 so as to form the above-mentioned inner or outer interlayer turn portions Ta, Tb between adjacent double pancake coils.

[0135] Other details of the configuration example in FIG. 16 may be the same as those of the configuration example in FIG. 13, FIG. 14A, or FIG. 14B, and therefore description thereof will be omitted.

[0136] <Another example configuration> Fig. 17 is an enlarged view of region R4 surrounded by a dashed line in Fig. 12, showing yet another configuration example of the third embodiment. In the configuration example of Fig. 17, an adhesive layer 12 is provided in each coil layer instead of the above-mentioned inter-turn insulation 15. That is, in the configuration example of Fig. 17, an adhesive layer 12 is provided between each pair of radially adjacent turn portions T in each coil layer. As a result, in each coil layer, the adhesive layer 12 forms a current bypass path that electrically connects each pair of radially adjacent turn portions T.

[0137] 17, the current bypass path formed by the adhesive layer 12 is a path through which a bypass current flows in the radial direction from any one of the turn portions T to the adjacent turn portion T via the adhesive layer 12. Note that, as shown in FIG. 17, in each coil layer, the adhesive layer 12 may be in contact with both of the turn portions T of each pair of radially adjacent turn portions T.

[0138] The adhesive layer 12 has a linear (e.g., tape-like) shape extending around a central axis C (see FIG. 12) along the superconducting wire 1. That is, in each coil layer, the adhesive layer 12 may extend around the central axis C while moving in the radial direction of the superconducting coil 11 along the superconducting wire 1 from a radially inner end of the superconducting wire 1 to a radially outer end of the superconducting wire 1.

[0139] In the configuration example of FIG. 17, similarly to the configuration example of FIG. 13, an interlayer insulating portion 14 is provided between each pair of coil layers adjacent to each other in the axial direction, and electrically insulates the coil layers from each other. In the configuration example of FIG. 17, unlike the configuration example of FIG. 13, an adhesive layer 12 does not need to be provided between the coil layers adjacent to each other in the axial direction. In the configuration example of FIG. 17, unlike the configuration examples of FIG. 13 and FIG. 14B, the conductor portion 13 and the interlayer conductor portion 16 may be omitted. Other matters regarding the configuration example of FIG. 17 may be the same as those in the configuration examples of FIG. 13, FIG. 14A, or FIG. 14B, and therefore description thereof will be omitted.

[0140] <Effects of the third embodiment> The third embodiment also provides the advantages (1) and (2) described above in the first embodiment. Moreover, the third embodiment also provides the same advantages as the advantages (3) to (6) described above in the first embodiment, as described below.

[0141] 13 to 16, the conductor portion 13 extends in the radial direction so as to be adjacent to a plurality of turn portions T arranged in the radial direction, and is electrically connected to the plurality of turn portions T via the adhesive layer 12. This makes it possible to configure a current bypass path having the above-mentioned effects (1) and (2). 17, each pair of radially adjacent turn portions T are electrically connected to each other by an adhesive layer 12 sandwiched between the turn portions T. This makes it possible to configure a current bypass path having the above-mentioned effects (1) and (2).

[0142] As shown in FIGS. 13 to 16, the inter-turn insulation portions 15 are provided between each pair of radially adjacent turn portions T to prevent the turn portions T from contacting each other in the axial direction.

[0143] 13 to 16, for each coil layer, adhesive layer 12 extends in the radial and circumferential directions so as to contact axial end faces of multiple (all) turn portions T of superconducting wire 1 forming that coil layer, and conductor portion 13 extends in the radial and circumferential directions so as to contact the axial end face (the entire axial end face) of adhesive layer 12. Therefore, cooling of superconducting wire 1 can be promoted by heat transfer from superconducting wire 1 to conductor portion 13 via adhesive layer 12.

[0144] The adhesive layer 12 mechanically bonds and integrates a plurality (all) of turn portions of the superconducting wire 1 in each coil layer.

[0145] The present invention is not limited to the above-mentioned embodiment, and various modifications may be made within the scope of the technical concept of the present invention. For example, a superconducting coil device according to an embodiment of the present invention may not have all of the above-mentioned features, and may have only some of the above-mentioned features. Furthermore, within the scope of solving at least some of the above-mentioned problems or obtaining at least some of the effects described in this specification, one or more of the components described in the claims and this specification may be omitted, or any combination of the components described in the claims and this specification may be possible.

[0146] In addition, any one of the following modified examples 1 to 7 may be adopted, or any combination of two or more of modified examples 1 to 7 may be adopted within a range that does not cause a contradiction. In this case, matters not described below may be the same as those described above, or may be appropriately changed.

[0147] (Change example 1) A bundle-type superconducting wire 1A may be used instead of the above-described superconducting wire 1. That is, in each of the above-described first to third embodiments, a bundle-type superconducting wire 1A in which a plurality of superconducting wires 1 are bundled together may be used instead of the above-described superconducting wire 1.

[0148] 18A and 18B are configuration examples showing a cross section of such a bundle-type superconducting wire 1A. In this modification example 1, a plurality of superconducting wires 1 (two in Figs. 18A and 18B) are bonded to each other via adhesive layer 12, and adhesive layer 12 forms a current bypass path between the plurality of superconducting wires 1. Adhesive layer 12 also has a function of bonding the plurality of superconducting wires 1 with binder 12a. Note that the relative positions of superconducting layers 2a in the two superconducting wires 1 constituting bundle-type superconducting wire 1A are different between Figs. 18A and 18B.

[0149] When the bundle-type superconducting wire 1A is used, in the first to third embodiments, the superconducting wire 1 may be read as the bundle-type superconducting wire 1A.

[0150] In conventional bundle-type superconducting wires, two superconducting wires are directly bonded together, so the contact resistance between the two superconducting wires is small and unstable, and changes depending on the position. This can cause a current drift when the superconducting coil is excited, and can cause an overcurrent to flow in the event of a quench.

[0151] In contrast, in this modified example 1, the multiple superconducting wires 1 constituting the bundle-type superconducting wire 1A are bonded via the adhesive layer 12, so that the contact resistivity between the multiple superconducting wires 1 via the adhesive layer 12 (current bypass path) is prevented from becoming too low, and the value can be adjusted to a desired value or range, thereby suppressing the above-mentioned uneven current and overcurrent.

[0152] (Change example 2) According to this modified example 2, when a superconducting coil 11 is formed using the bundle-type superconducting wire 1A of modified example 1, the current bypass path (adhesive layer 12 and conductor portion 13) and the interlayer current bypass path (interlayer conductor portion 16) connecting multiple turn portions may be omitted.

[0153] Fig. 19A is an enlarged view of region R1 surrounded by a dashed line in Fig. 1, showing a configuration example of Modification Example 2. As shown in Fig. 19A, a configuration in which bundle-type superconducting wire 1A is wound around central axis C while moving in the axial direction is regarded as one coil layer in the radial direction, and superconducting coil 11 may have multiple coil layers adjacent to each other in the radial direction or one coil layer. In each coil layer, inter-turn insulation 15 is provided between each pair of turn portions T adjacent to each other in the axial direction. In addition, interlayer insulation 14 is provided between each pair of coil layers adjacent to each other in the radial direction.

[0154] FIG. 19B is an enlarged view of region R4 surrounded by a dashed line in FIG. 12, showing a configuration example of Modification Example 2. As shown in FIG. 19B, a configuration in which bundle-type superconducting wire 1A extends from an inner end in the radial direction to an outer end in the radial direction while rotating around central axis C with the axial position remaining constant is regarded as one coil layer in the axial direction, and superconducting coil 11 may have multiple coil layers adjacent to each other in the axial direction or one coil layer. In each coil layer, inter-turn insulation 15 is provided between each pair of turn portions T adjacent to each other in the radial direction. In addition, inter-layer insulation 14 is provided between each pair of coil layers adjacent to each other in the axial direction.

[0155] (Change example 3) In the above description, the superconducting wire 1 is constituted by the superconducting layer 1a which is a high-temperature superconductor, but it may be constituted by including a superconducting layer 1a which is a so-called low-temperature superconductor. In this case, the superconducting wire 1 may be, for example, a low-temperature superconductor covered with a stabilizing layer made of a material (e.g., copper or stainless steel) which stabilizes the superconducting state. The low-temperature superconductor may have a transition temperature which is equal to or higher than the boiling point of liquid helium (4.2K) and equal to or lower than 25K.

[0156] (Change example 4) According to the data of Example 3 in FIG. 7A, in any embodiment of the superconducting coil 11, the superconducting coil 11 can be manufactured by selecting different values ​​or ranges of contact resistivity depending on the parts of the superconducting coil 11. This makes it possible to effectively avoid excessive temperature rises due to quenching and excessive increase in induced conduction (resulting in mechanical damage) compared to the case where a single contact resistivity value is set for all parts. For example, in the superconducting coil 11, the contact resistivity of a part that is likely to become a quenching starting point may be set lower than that of other parts, and in a part where induced current is likely to increase due to magnetic coupling between the turn parts T, etc., it may be set higher than that of other parts. This makes it possible to suppress the temperature rise at the quenching starting point and suppress localized increase in induced conduction. The level of induced current tends to be high not only due to the influence of magnetic coupling, but also in parts where the experienced magnetic field is low and the superconducting critical current is high. It is also effective to select a higher contact resistivity value in such parts. The value of the contact resistivity can be selected by electrical circuit analysis or thermal conduction analysis based on the specifications of a specific superconducting coil.

[0157] (Change example 5) FIG. 20A is an enlarged view of FIG. 5A, but shows the case of Modification Example 5. That is, FIG. 20A shows a configuration example in which the adhesive layer 12 of Modification Example 5 is applied to the adhesive layer 12 of the first embodiment. However, the adhesive layer 12 of Modification Example 5 may be applied to the adhesive layer 12 of the second embodiment, the third embodiment, Modification Example 1, or Modification Example 2. That is, the adhesive layer 12 of Modification Example 5 described below with reference to FIG. 20A or FIGS. 20B and 20C described later may be any of the adhesive layers 12 of the first embodiment, the second embodiment, the third embodiment, Modification Example 1, and Modification Example 2. In addition, in Modification Example 5, one or both of Modification Examples 3 and 4 described above may be adopted.

[0158] The adhesive layer 12 of this modification example 5 has a conductive fibrous body 12d as shown in FIG. 20A, instead of the powder-like conductive filler 12b and the powder-like insulating filler 12c described above. That is, in this modification example 5, the adhesive layer 12 has a binder 12a and a fibrous body 12d. The adhesive layer 12 may be formed, for example, by impregnating or applying the binder 12a to the fibrous body 12d (for example, by vacuum pressure impregnation). Note that the binder 12a may be applied to one or both of the objects to be bonded (the superconducting wire 1 and the conductor portion 13 in the example of FIG. 20A) and the fibrous body 12d, and then the fibrous body 12d may be sandwiched between the objects to be bonded so as to press the objects to the fibrous body 12. In this way, the adhesive layer 12 may be formed.

[0159] The fibrous body 12d is formed of conductive fibers 12d1. The fibrous body 12d may be a fiber fabric woven with the fibers 12d1, or a fiber knitted fabric knit with the fibers 12d1. The fibrous body 12d may be formed, for example, in a sheet shape. In this case, the thickness direction of the sheet-like fibrous body 12d may be the same as the thickness direction of the adhesive layer 12. In one example, the fibrous body 12d may be a conductive mesh (for example, a metal mesh) formed with conductive fibers 12d1.

[0160] The fibrous body 12d is conductive and thus provides electrical conductivity to the adhesive layer 12. On the other hand, since the fibrous body 12d is formed of the fibers 12d1, the entire contact surface of the adhesive layer 12 with the superconducting wire 1 is not a conductive portion (fibrous body 12d), and the proportion of electrical conductivity in the contact surface can be reduced according to the density of the fibers 12d (e.g., the opening ratio of the metal mesh as the fibrous body 12d). In this way, the fibrous body 12d forms a resistance reduction suppression structure that provides electrical conductivity to the adhesive layer 12 while suppressing a reduction in the contact resistance (contact resistivity) with the superconducting wire 1.

[0161] Another configuration example of the fibrous body 12 in this modified example 5 will be described with reference to Fig. 20B and Fig. 20C. Fig. 20B is an enlarged cross-sectional view showing another configuration example of the fibrous body 12d in modified example 5. Fig. 20C is an enlarged view of Fig. 5A, and shows the case where the fibrous body 12d in Fig. 20B is used in modified example 5.

[0162] In this other configuration example, the fibrous body 12d may be rolled or cut in advance before using the adhesive layer 12. That is, as shown in FIG. 20B, the fibrous body 12d is rolled or cut so that a large number of local regions 12f (local regions 12f on the left side of FIG. 20B) in the fibrous body 12d that contact the superconducting wire 1 become flat or approach a plane. As a result, a large number of planar or approaching a plane local regions 12f form an approximately planar portion that contacts the superconducting wire 1. These local regions 12f are located along one imaginary plane. Moreover, by such rolling or cutting, a large number of local regions 12f also form an approximately planar portion (for example, in contact with the conductor portion 13) on the opposite side of the fibrous body 12d (the right side of FIG. 20C) to the above, so as to become flat or approach a plane.

[0163] In this way, by forming a substantially flat portion in the fiber body 12d that contacts the superconducting wire 1, the contact area between the fiber body 12d and the superconducting wire 1 can be adjusted. This makes it possible to control the contact resistivity (bypass resistance) with higher precision. Similarly, the contact area between the fiber body 12d and the conductor portion 13 can also be adjusted as shown in FIG. 20C.

[0164] According to this modification example 5, the contact resistance can be controlled to any value by changing the density of fibers 12d (e.g., the opening ratio of a metal mesh as fibrous body 12d) or the area of ​​the substantially planar portion of multiple local regions 12f in FIG. 20B. FIG. 21 shows the results of measuring the contact resistivity (bypass resistance) between adhesive layer 12 and superconducting wire 1 when a metal mesh is used as fibrous body 12d. This measurement was performed for adhesive layers 12 having different metal mesh densities (mesh area ratios). The horizontal axis of FIG. 21 shows the ratio of the metal portion on the surface of the sheet-like metal mesh (corresponding to the density of the metal mesh). As can be seen from FIG. 21, the contact resistivity can be adjusted by changing the density of the metal mesh.

[0165] According to this modification example 5, as shown in FIG. 20A or FIG. 20C, the adhesive layer 12 is formed of the binder 12a and the fibrous body 12d, so that the current bypass path for the superconducting coil 11 can be formed relatively easily by the adhesive layer 12.

[0166] Also in this modified example 5, similarly to the above-described first embodiment, the thickness of the adhesive layer 12 can be reduced. For example, the thickness of the adhesive layer 12 can be reduced to 30 μm or less.

[0167] According to the fifth modified example, the fibrous body 12d may be formed of regularly arranged fibers 12d1, which makes it possible to stabilize the contact resistivity between the adhesive layer 12 and the superconducting wire 1.

[0168] Fig. 22 shows the measurement results corresponding to Fig. 9A, but shows the measured values ​​of the contact resistivity (bypass resistance) in the case of Modified Example 5. That is, a superconducting coil device 10 in which the adhesive layer 12 according to Modified Example 5 is applied to the first embodiment was actually manufactured, and the contact resistivity (bypass resistance) was measured with respect to the repetition of the above-mentioned cooling cycle also in Modified Example 5, as in the case of Fig. 9A. As can be seen from Fig. 22, the contact resistivity of the adhesive layer 12 with the superconducting wire 1 is highly stable with respect to the repetition of the cooling cycle also in Modified Example 5.

[0169] (Change Example 6) In the above-mentioned modified example 5, the adhesive layer 12 further includes, in addition to the above-mentioned binder 12a and fibrous body 12d, one or both of the powder-like conductive filler 12b and the powder-like insulating filler 12c described in the first embodiment etc. Here, as the conductive filler 12b, a plurality of types of conductive fillers having different electrical conductivities (for example, the above-mentioned first type of conductive filler 12b1 and the second type of conductive filler 12b2) may be provided.

[0170] In this way, by using one or both of powder-like conductive filler 12b and powder-like insulating filler 12c in addition to fibrous body 12d (e.g., metal mesh) in adhesive layer 12, it is possible to control the value of contact resistance (contact resistivity) between adhesive layer 12 and superconducting wire 1 with greater precision.

[0171] (Change Example 7) 17 described above, in each coil layer, an adhesive layer 12 may be provided instead of the inter-turn insulation 15. That is, in this seventh modified example, an adhesive layer 12 is provided between each pair of axially adjacent turn portions T in each coil layer, the adhesive layer 12 being in contact with both turn portions T. As a result, in each coil layer, the adhesive layer 12 forms a current bypass path that electrically connects each pair of axially adjacent turn portions T.

[0172] Moreover, this modified example 7 may be configured as follows. An interlayer insulating portion 14 is provided between each pair of radially adjacent coil layers to electrically insulate the coil layers from each other. Unlike FIG. 3, the adhesive layer 12 may not be provided between the radially adjacent coil layers. Unlike FIG. 3, the conductor portion 13 may be omitted. Other matters regarding this modified example 7 may be the same as those in the first embodiment. [Explanation of symbols]

[0173] 1. Superconducting wire 1a Superconducting layer 1b Substrate 1c Stabilization layer 1A bundle type superconducting wire 2 Reels 3 Retaining member 10. Superconducting coil device 11 Superconducting coil 12 Adhesive layer 12a Binder 12b Conductive filler 12b1 First type of conductive filler 12b2 Second type of conductive filler 12c Insulating Filler 12d Fibrous body 12d1 Fiber 12f Local Area 13 Conductor 14 Interlayer insulation 15 Turn-to-turn insulation 16 Interlayer conductor 17 Interlayer insulation 18 Connection C center axis T-turn section Ta interlayer turn part

Claims

1. a superconducting coil formed by winding a superconducting wire into a coil shape; an adhesive layer that constitutes at least a part of a current bypass path for the superconducting coil, that contains a binder and that is provided with electrical conductivity; A superconducting coil device, wherein the adhesive layer has a resistance reduction suppression structure that imparts electrical conductivity to the adhesive layer while suppressing a reduction in contact resistance with the superconducting wire.

2. The superconducting coil device according to claim 1 , wherein the resistance decrease suppression structure includes a conductive filler and an insulating filler.

3. The superconducting coil device according to claim 1 , wherein the resistance decrease suppression structure includes a fibrous body formed of conductive fibers.

4. 4. The superconducting coil device according to claim 3, wherein the resistance decrease suppression structure further includes one or both of a powder-like conductive filler and a powder-like insulating filler.

5. the adhesive layer contacts a plurality of turn portions of the superconducting coil on one side in a thickness direction of the adhesive layer, a conductor portion that is in contact with the adhesive layer on the other side in the thickness direction of the adhesive layer and extends along the adhesive layer, 5. The superconducting coil device according to claim 1, wherein the adhesive layer and the conductor portion constitute the current bypass path that electrically connects the plurality of turn portions to each other.

6. The superconducting wire is a bundle of a plurality of superconducting wires, The superconducting coil device according to any one of claims 1 to 4, wherein the plurality of superconducting wires are bonded to each other via the adhesive layer, and the adhesive layer constitutes the current bypass path that electrically connects the plurality of superconducting wires to each other.

7. 5. The superconducting coil device according to claim 2, wherein the adhesive layer contains, as the conductive filler, a plurality of types of conductive filler having mutually different electrical conductivities.

8. 6. The superconducting coil device according to claim 5, further comprising an inter-turn insulation portion provided in a region sandwiched between the turn portions of each pair of adjacent pairs.

9. the superconducting coil has a configuration in which the superconducting wire is wound around a central axis of the superconducting coil while moving in an axial direction of the superconducting coil, The superconducting wire is a single continuous superconducting wire, or a plurality of superconducting wires connected in series, and the configuration is regarded as one coil layer, forming a plurality of coil layers arranged in the radial direction of the superconducting coil; The superconducting coil device according to claim 5 , wherein the current bypass path is configured for each of the plurality of coil layers.

10. 10. The superconducting coil device according to claim 9, further comprising an interlayer insulating portion provided between inner and outer coil layers adjacent to each other in the radial direction, electrically insulating the coil layers from each other.

11. the superconducting wire extends around the central axis of the superconducting coil while moving axially from one axial end to the other axial end to form an inner coil layer, and then extends around the central axis from the other axial end to the one axial end radially outside the inner coil layer to form an outer coil layer; 10. The superconducting coil device according to claim 9, further comprising an interlayer current bypass path that electrically connects one or more turn portions located at the other axial end of the inner coil layer and one or more turn portions located at the other axial end of the outer coil layer.

12. The interlayer current bypass path is a portion of the adhesive layer that is radially sandwiched between the other axial end of the inner coil layer and the other axial end of the outer coil layer; a portion of the conductor portion sandwiched in a radial direction between the other axial end portion of the inner coil layer and the other axial end portion of the outer coil layer; 12. The superconducting coil device according to claim 11, further comprising an interlayer conductor portion that electrically connects the portion of the conductor portion to the other axial end of the inner or outer coil layer.

13. 10. The superconducting coil device of claim 9, wherein for each coil layer, the adhesive layer extends in the axial and circumferential directions of the superconducting coil so as to contact the outer or inner peripheral surfaces of the multiple turn portions of the superconducting wire that form the coil layer, and the conductor portion extends in the axial and circumferential directions so as to contact the outer or inner peripheral surface of the adhesive layer.

14. the superconducting coil has a configuration in which the superconducting wire is wound around a central axis of the superconducting coil while moving radially outward while the axial position of the superconducting coil remains constant, The superconducting wire is a single continuous superconducting wire, or a plurality of superconducting wires connected in series, and the configuration is regarded as one coil layer, forming a plurality of coil layers arranged in the axial direction of the superconducting coil; The superconducting coil device according to claim 5 , wherein the current bypass path is configured for each of the plurality of coil layers.

15. 15. The superconducting coil device according to claim 14, further comprising an interlayer insulating portion provided between coil layers adjacent to each other in the axial direction, electrically insulating the coil layers from each other.

16. 15. The superconducting coil device according to claim 14, further comprising an interlayer conductor portion that electrically connects a radially innermost or outermost turn portion of one of the coil layers to a radially innermost or outermost turn portion of the other of the coil layers, the interlayer conductor portion being provided for the coil layers adjacent to each other in the axial direction.

17. For the coil layers adjacent to each other in the axial direction, the superconducting wire extends continuously in the circumferential direction of the superconducting coil from a position constituting the innermost or outermost turn portion in one of the coil layers, transitions radially inward or outward, and transitions in the axial direction toward the other coil layer to form an interlayer turn portion, and then extends continuously radially inward or outward, transitioning in the axial direction toward the other coil layer to a position constituting the innermost or outermost turn portion in the other coil layer, The superconducting coil device according to claim 16 , wherein the interlayer conductor portion is electrically connected to the interlayer turn portion.

18. the superconducting coil has a configuration in which the superconducting wire is wound around a central axis of the superconducting coil while moving radially outward while the axial position of the superconducting coil remains constant, The superconducting coil device according to any one of claims 1 to 4, wherein the adhesive layer is provided between each pair of radially adjacent turn portions in the superconducting coil, thereby forming a current bypass path that electrically connects the turn portions.

19. 5. The superconducting coil device according to claim 1, wherein the superconducting wire includes a superconducting layer of a high-temperature superconductor or a low-temperature superconductor.

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