Superconducting coil

Abstract

This invention provides a superconducting coil that enables both hot spot avoidance and suppression of excitation lag by controlling the inter-wire resistance. [Solution] The superconducting coil comprises superconducting wires wound from the inner circumference of the superconducting coil, offset in the axial direction of the superconducting coil, and stacked radially within the superconducting coil. The superconducting coil also comprises a conductive material filled between the wound superconducting wires and a coating region of insulating material formed on the surface of the superconducting wires. The superconducting wires have exposed regions where the surface of the superconducting wires is exposed outside the coating region.

Description

Technical Field

[0001] The present invention relates to a superconducting coil.

Background Art

[0002] Compared with a normal conducting coil, a superconducting coil can conduct a current with a current density about several tens to several hundreds of times, and there is no loss due to electrical resistance. Therefore, superconducting coils are applied to MRI (Magnetic Resonance Imaging) devices, NMR (Nuclear Magnetic Resonance) devices, magnets for accelerators, and silicon single crystal lifting magnets. In recent years, the commercialization of superconducting coils using high-temperature superconducting wires (REBCO, BSCCO) that can maintain a superconducting state in a high-temperature region and magnesium diboride (MgB2) wires has been progressing. Further, as a method for avoiding the generation of hot spots and burnout due to damage to the superconducting wire of the superconducting coil, there is a non-insulated coil method. Furthermore, in a superconducting coil by the non-insulated coil method, as a method for avoiding excitation delay, a configuration in which an insulating layer is disposed between layers has been proposed (for example, see Patent Document 1). In this superconducting coil, when superconducting wires are laminated in the coil diameter direction by winding, insulating layers are disposed at regular intervals.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The superconducting coil described in Patent Document 1 above has insulating layers interposed at regular intervals, allowing control of the radial resistance of the superconducting coil. However, the superconducting coil described in Patent Document 1 has limited control over inter-wire resistance, such as being unable to control the inter-wire resistance of the axial superconducting wires wound in the same layer. Therefore, the superconducting coil described in Patent Document 1 has a narrow range of controllable inter-wire resistance, making it difficult to achieve both hot spot avoidance and excitation delay suppression.

[0005] To solve the above-mentioned problems, the present invention provides a superconducting coil that can achieve both hot spot avoidance and excitation delay suppression by controlling the inter-line resistance.

[0006] Furthermore, the above-mentioned and other objectives of the present invention, as well as the novel features of the present invention, will be made clearer by the description herein and the accompanying drawings. [Means for solving the problem]

[0007] The superconducting coil of the present invention comprises superconducting wires wound from the inner circumference of the superconducting coil, offset in the axial direction of the superconducting coil, and stacked radially within the superconducting coil. The superconducting coil also comprises a conductive material filled between the wound superconducting wires and a coating region of insulating material formed on the surface of the superconducting wires. The superconducting wires have exposed regions where the surface of the superconducting wires is exposed outside the coating region.

[0008] Furthermore, the superconducting coil of the present invention comprises superconducting wires that are wound from the inner circumference of the superconducting coil, offset in the axial direction of the superconducting coil, and stacked in the radial direction of the superconducting coil. The superconducting coil also comprises an insulating material filled between the wound superconducting wires and a coating region of a conductive material formed on the surface of the superconducting wires. The superconducting wires have exposed regions where the surface of the superconducting wires is exposed outside of the coating region. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a superconducting coil that can achieve both hot spot avoidance and excitation delay suppression by controlling the inter-line resistance.

[0010] Furthermore, issues, configurations, and effects other than those mentioned above will be clarified by the following description of the embodiments. [Brief explanation of the drawing]

[0011] [Figure 1] This is a perspective view of a superconducting coil. [Figure 2] Figure 1 shows a cross-section of the AA wire of the superconducting coil and a magnified view of a portion of the coil winding section. [Figure 3] This diagram shows the layout of the manufacturing equipment for conductive coils. [Figure 4] This is a flowchart showing the manufacturing method of a superconducting coil. [Figure 5] This diagram shows the layout of the manufacturing equipment for conductive coils. [Figure 6] This is a flowchart showing the manufacturing method of a superconducting coil. [Figure 7] Figure 1 is a magnified view of a portion of the coil winding section in the AA wire cross-section of the superconducting coil shown. [Figure 8] Figure 1 shows a cross-section of the AA wire of the superconducting coil and a magnified view of a portion of the coil winding section. [Figure 9] This diagram shows the layout of the manufacturing equipment for conductive coils. [Figure 10] Figure 1 is a magnified view of a portion of the coil winding section in the AA wire cross-section of the superconducting coil shown. [Modes for carrying out the invention]

[0012] Hereinafter, an example of a superconducting coil according to an embodiment of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following example. In the figures described below, common components are denoted by the same reference numerals. Furthermore, in the drawings used herein, identical or corresponding components are denoted by the same reference numerals, and repeated descriptions of these components may be omitted. The description will be given in the following order. 1. Overview of the superconducting coil 2. First embodiment of the superconducting coil 3. Second embodiment of the superconducting coil 4. Third embodiment of the superconducting coil 5. Fourth embodiment of the superconducting coil

[0013] 〈1. Overview of the superconducting coil〉 Prior to the description of the present invention, an overview of the superconducting coil will be described. Conventional superconducting coils are generally composed of low-temperature superconducting wires typified by NbTi. And the superconducting coil using this low-temperature superconducting wire is maintained and operated in an extremely low temperature state of about 4K using a refrigerant typified by liquid helium and a refrigerator. However, in recent years, due to the depletion of helium resources in natural gas fields in the United States and the delay in the development of new helium supply sources due to the deterioration of the social situation, the price of helium has been soaring. Therefore, the commercialization of superconducting coils that employ high-temperature superconducting wires (REBCO, BSCCO) capable of maintaining a superconducting state in a temperature range higher than the liquid helium temperature or magnesium diboride (MgB2) wires as superconducting wires has been progressing. These high-temperature superconducting coils using these high-temperature superconducting wires or MgB2 wires operate in a temperature range of 10K or higher. In a temperature range of 10K or higher, the specific heat of the material constituting the superconducting wire becomes more than 10 times larger compared to that near 4K. For this reason, it becomes difficult for the coil temperature to rise, and the superconducting state can be maintained relatively easily with only a refrigerator.

[0014] However, for high-temperature superconducting coils, the strain resistance performance of any superconducting wire is inferior compared to conventional low-temperature superconducting wires. Therefore, during the process of applying insulation coating or during coil manufacturing, damage and the like are likely to occur, and it may be difficult to exhibit the predetermined critical current performance over the entire length. For example, when a high-temperature superconducting coil is energized with a damaged location in the superconducting wire, before reaching the target current value, it locally undergoes a normal-conducting transition, and the superconducting wire burns out due to excessive Joule heating. Also, even when there is no damage to the superconducting wire, if a normal-conducting transition occurs in a part of the coil due to some heat input, since it is difficult for the temperature of other parts to rise, the normal-conducting region does not expand throughout the coil, and hot spots where the temperature rises locally occur. When hot spots occur, the superconducting wire may be damaged due to thermal strain caused by the temperature difference with the surroundings.

[0015] As a method for avoiding hot spot generation and burnout due to damage to the superconducting wire, there is the non-insulated coil method. In the non-insulated coil method, the superconducting wire is wound without insulation, and the superconducting wires are electrically contacted with each other between rows and between layers within the coil winding. Thereby, even when a part of the superconducting wire undergoes a normal-conducting transition, a current bypass circuit can be provided between rows and between layers. By providing a current bypass circuit between rows and between layers, it is possible to reduce the Joule heating due to the normal-conducting transition of the superconducting coil formed by the non-insulated coil method and avoid the generation of hot spots.

[0016] In superconducting coils formed by the non-insulated coil method, the lower the resistance between superconducting wires, the faster the current bypasses the normal conducting transition zone through current bypass circuits between rows and layers. Furthermore, with the non-insulated superconducting wires, during current sweeping, current is generated not only along the superconducting wires but also across the superconducting wires. When current sweeping stops, the current across the superconducting wires is attenuated by the electrical resistance (inter-wire resistance) between the superconducting wires, leaving only the current flowing along the superconducting wires with zero electrical resistance. However, the lower the resistance between the superconducting wires, the longer the time required for attenuation, and the longer it takes to reach the designed magnetic field strength. This is called excitation lag and is a challenge for superconducting coils formed by the non-insulated coil method. In particular, in a tightly wound coil, where circular cross-section superconducting wires are wound while shifting them axially and stacked in a barrel-like fashion in the coil diameter direction, up to seven wires come into contact with each other within the winding. This results in lower inter-wire resistance and a more pronounced excitation delay.

[0017] Therefore, in the superconducting coil of the present invention, in a tightly wound coil structure in which superconducting wires are stacked in a bale-like manner in the coil diameter direction, a covered region is formed where a portion of the superconducting wires is covered with an insulating material or a conductive material, and an exposed region is formed where the surface of the superconducting wires is exposed. Furthermore, conductive resin or insulating material is filled between the superconducting wires. By covering the surface with an insulating material or a conductive material, the exposed area of ​​the superconducting wires is controlled. This allows for control of conductivity and resistance between adjacent wires. As a result, the inter-wire resistance of an uninsulated coil can be controlled over a wide range. In particular, in the superconducting coil with the above configuration, the position of the insulating material or conductive material covering the superconducting wires can be arbitrarily set, so the inter-wire resistance of the superconducting wires in the coil diameter direction and the inter-wire resistance of the axial superconducting wires wound in the same layer can be arbitrarily adjusted. This configuration allows for the control of the inter-wire resistance of the uninsulated coil, providing a superconducting coil that can simultaneously avoid hot spots and suppress excitation delay.

[0018] <2. First Embodiment of a Superconducting Coil> Figure 1 shows a perspective view of a superconducting coil. Figure 2 shows a cross-sectional view of the superconducting coil 10 shown in Figure 1, along line AA. Figure 2 shows the entire cross-sectional view of the superconducting coil along line AA, as well as an enlarged view of a portion of the coil winding section of the superconducting coil. The superconducting coil 10 shown in Figures 1 and 2 comprises a coil winding 34 made of superconducting wire 30 wound around a coil bobbin 11. The coil winding 34 is constructed by winding the superconducting wire 30 in the circumferential direction 23, shifting in the axial direction 24, starting from the central axis 21 side of the superconducting coil 10, i.e., the inner circumference side, and stacking them in a bale-like manner in the coil radial direction 22. The superconducting wire 30 has a circular cross-section.

[0019] The superconducting coil 10 includes an insulating material 52 for electrical insulation between the coil winding 34 and the coil bobbin 11. The superconducting coil 10 also includes a cooling plate 53 adjacent to one side of the coil winding 34 in the axial direction 24. The cooling plate 53 is a copper or aluminum plate thermally connected to the refrigerator. The superconducting coil 10 also includes an insulating material 51 for electrical insulation between the coil winding 34 and the cooling plate 53. The insulating materials 51 and 52 are formed from, for example, FRP (Fiber Reinforced Plastics) consisting of insulating resin and glass fibers, or from a polyimide sheet.

[0020] The superconducting wire 30 is, for example, REBCO (a copper oxide superconductor containing rare earth elements: REBa2CuO2). y RE stands for rare earth element) and BSCCO (bismuth-based superconductor: Bi2Sr2Ca2Cu3O 10The superconducting coil 10 is composed of high-temperature superconducting wires such as ), magnesium diboride (MgB2) wires, and low-temperature superconducting wires such as Nb3Sn. Preferably, the superconducting wire 30 is composed of magnesium diboride (MgB2) wire. MgB2 is produced by heat-treating magnesium powder and boron powder inside the wire at a high temperature of 500°C or higher. For this reason, coil manufacturing methods using MgB2 wire are mainly classified into two types: the wind-and-react method (hereinafter referred to as the W&R method) and the react-and-wind method (hereinafter referred to as the R&W method). It is preferable that the superconducting coil 10 is equipped with MgB2 wire produced by the R&W method as the superconducting wire 30.

[0021] The W&R method involves winding MgB2 wire onto a coil bobbin 11 before heat treatment, and then heat-treating the MgB2 wire, including the coil bobbin 11, to produce superconducting wire 30 and form a superconducting coil 10. The superconducting wire 30, made of MgB2, is a superconductor that can tolerate only slight distortion of about 0.2 to 1.0%. In the W&R method, the MgB2 that becomes the superconducting wire 30 is generated after winding. Therefore, damage to the MgB2 wire during the winding process can be prevented.

[0022] On the other hand, the R&W method involves heat-treating MgB2 wire to produce superconducting wire 30, and then winding this heat-treated superconducting wire 30 onto a coil bobbin 11 to form a superconducting coil 10. The R&W method does not require the heat resistance of over 500°C required for the coil bobbin 11 and insulating materials 52 and 51 in the W&R method. Furthermore, the R&W method does not require a large furnace capable of heat-treating the entire superconducting coil 10, which is required in the W&R method. In addition, the R&W method does not require heat-resistant materials such as glass braiding applied along the entire length for insulation of the MgB2 wire itself, as is required in the W&R method. For these reasons, the R&W method is more likely to reduce manufacturing costs than the W&R method.

[0023] However, in the R&W method, the superconducting wire 30, which is made of heat-treated MgB2 wire, may be damaged during the winding process. If damage occurs to the superconducting wire 30 in the R&W method, a normal conduction transition will occur at the damaged location in the superconducting coil 10. Then, the Joule heating caused by the normal conduction transition will create a hot spot, which may cause the superconducting wire 30 to burn out. As a countermeasure, the above-mentioned non-insulated coil method has been proposed. In the non-insulated coil method, by omitting the electrical insulation (insulating layer) applied to the surface of the superconducting wire 30, the superconducting wires 30 are actively short-circuited within the coil winding 34. This makes it possible to create current paths that bypass the normal conduction transition area inside the coil winding 34 between rows and layers of the superconducting wire 30. As a result, the superconducting coil 10 can suppress the occurrence of hot spots by reducing Joule heating.

[0024] The superconducting coil 10 has conductive material 32 filled between the wires of tightly wound superconducting wires 30. Examples of conductive material 32 include conductive resin, low dielectric metal, and conductive paste. Preferably, the conductive material 32 is an epoxy resin, phenoxy resin, or cyanoacrylate resin in which conductive fillers such as graphite, copper, or silver are dispersed. In the non-insulated coil method, the smaller the resistance between the wires, the faster the current can bypass the normal conduction transition zone. For this reason, the superconducting coil 10 has conductive material 32 filled between the superconducting wires 30. The filling with conductive material 32 further reduces the inter-wire resistance of the superconducting coil 10.

[0025] Furthermore, as shown in Figure 2, the superconducting coil 10 has a covered region where a portion of the surface of the superconducting wire 30 is covered with an insulating material 33. The superconducting coil 10 also has an exposed region 31 where the surface of the superconducting wire 30 is exposed outside the covered region of the insulating material 33. In other words, the superconducting wire 30 has a covered region of the insulating material 33 and an exposed region 31. The exposed region 31 of the superconducting wire 30, other than the covered region of the insulating material 33, is in contact with the conductive material 32 or an adjacent superconducting wire 30. The insulating material 33 is preferably an insulating resin, for example, polyurethane paint or silicone varnish is preferred.

[0026] In the superconducting coil 10 shown in Figure 2, insulating material 33 is formed on the outer circumference of the superconducting wire 30 in the coil radial direction 22 and on both sides in the axial direction 24 of the superconducting wire 30, with an exposed region 31 formed only on the inner circumference in the coil radial direction 22. Therefore, in the superconducting coil 10, insulating material 33 is formed between adjacent superconducting wires 30 in the coil radial direction 22 and the axial direction 24. Furthermore, the insulating material 33 is formed continuously on the surface of the superconducting wire 30, but is formed separately between adjacent superconducting wires 30. Furthermore, in the superconducting coil 10, adjacent superconducting wires 30 do not directly contact each other, but rather contact each other via an insulating material 33. In addition, in the superconducting coil 10, adjacent superconducting wires 30 are electrically connected to each other via a conductive material 32 filled between them, at the exposed regions 31 where the insulating material 33 is not formed. Therefore, in the superconducting coil 10, no direct current bypass is formed between adjacent superconducting wires 30, and a current bypass is formed from the exposed regions 31 of the superconducting wires 30 via the conductive material 32.

[0027] The region on which the insulating material 33 is formed on the superconducting wire 30 is not particularly limited. For example, the insulating material 33 may be formed only on the outer circumference in the coil radial direction 22 of the superconducting wire 30, with the surface exposed in the axial direction 24 and on the inner circumference in the coil radial direction 22. Alternatively, the insulating material 33 may be formed only on the axial direction 24 of the superconducting wire 30, with exposed regions 31 formed on the outer circumference and inner circumference in the coil radial direction 22. Furthermore, the insulating material 33 does not have to be formed continuously on the surface of the superconducting wire 30. For example, the insulating material 33 may be formed separately on both sides of the axial direction 24 of the superconducting wire 30, or the insulating material 33 may be formed separately on the outer circumference and inner circumference in the coil radial direction 22, respectively.

[0028] In the superconducting coil 10 with the above configuration, the resistance of the current crossing between the superconducting wires 30 is suppressed by the insulating material 33 formed on the surface of the superconducting wires 30. Therefore, the superconducting coil 10 can adjust the resistance between the wires that would occur if the superconducting wires 30 were not insulated, and suppress the excitation delay. Furthermore, in the superconducting coil 10, conductive material 32 is filled between the superconducting wires 30. As a result, in the superconducting coil 10, a current bypass circuit is formed from the exposed surface area 31 of the superconducting wires 30 to adjacent superconducting wires 30. Therefore, the superconducting coil 10 can suppress the generation of hot spots due to damage to the superconducting wires 30. Furthermore, the superconducting coil 10 can arbitrarily adjust the resistance of current crossing between superconducting wires 30 by adjusting the ratio of the area of ​​the covering region of the insulating material 33 formed on the surface of the superconducting wires 30 to the area of ​​the exposed region 31. In addition, by adjusting the formation position of the insulating material 33, the superconducting coil 10 can be configured to have structures that bring adjacent superconducting wires 30 into contact with each other in the coil radial direction 22 or axial direction 24, or structures that restrict contact between superconducting wires 30. As a result, the superconducting coil 10 can arbitrarily adjust the resistance of current crossing between superconducting wires 30. Therefore, the superconducting coil 10 can increase the controllable range of inter-wire resistance, making it possible to achieve both hot spot avoidance and excitation delay suppression. In particular, the superconducting coil 10 can employ a configuration in which contact between superconducting wires 30 is suppressed by an insulating material 33, and a current bypass circuit is mainly formed via a conductive material 32. Generally, the resistance of the current bypass path via the conductive material 32 is often greater than that of direct contact between superconducting wires 30. For this reason, the superconducting coil 10 is more effective at suppressing excitation delay.

[0029] [Method for manufacturing superconducting coils] Next, the manufacturing method for the superconducting coil 10 described above will be explained. Figure 3 shows the arrangement of the manufacturing equipment for the superconducting coil 10. The manufacturing equipment for the superconducting coil 10 is arranged in the following order: a feed bobbin 70 for holding the superconducting wire 30, a coating equipment 71 for insulating material 33, and a coil bobbin 11. The feed bobbin 70 feeds the superconducting wire 30, for example, made of uninsulated MgB2 wire, to the coil bobbin 11. The superconducting wire 30 fed out from the feed bobbin 70 is coated with insulating material 33 by the coating equipment 71. The superconducting wire 30 coated with insulating material 33 is then wound onto the coil bobbin 11, and wound on the coil bobbin 11 while being shifted in the axial direction 24, and stacked in a bale-like manner in the coil radial direction 22.

[0030] The coating equipment 71 is equipped with a spray device that ejects insulating material 33. The direction in which the insulating material 33 is ejected from the coating equipment 71 is from the outer circumference to the inner circumference in the coil diameter direction 22 of the coil bobbin 11. By ejecting the insulating material 33 in this direction, insulating material 33 is formed on the superconducting wire 30 only on the outer circumference in the coil diameter direction 22 and on the axial direction 24 of the superconducting wire 30, and an exposed region 31 can be formed on the inner circumference in the coil diameter direction 22 of the superconducting wire 30. Furthermore, by changing the ejection position and direction of the insulating material 33, the coated region where insulating material 33 is formed and the exposed region 31 can be formed on the superconducting wire 30 at any desired position.

[0031] Next, Figure 4 shows a flowchart of the manufacturing method for the superconducting coil 10 using the manufacturing equipment for the superconducting coil 10 described above. First, the superconducting wire 30 is fed from the feed bobbin 70 towards the coil bobbin 11 (step S10). Next, using the coating equipment 71, the insulating material 33 is applied to the superconducting wire 30 being transported from the feed bobbin 70 toward the coil bobbin 11 (step S11). Next, the superconducting wire 30 coated with insulating material 33 is wound onto the coil bobbin 11 (step S12). Next, conductive material 32 is filled between the superconducting wires 30 wound on the coil bobbin 11 (step S13). Filling with conductive material 32 can be done, for example, by applying the conductive material 32 to the coil windings 34 from the outer circumference of the coil radial direction 22 of the coil bobbin 11, or by immersing the coil bobbin 11 with the superconducting wires 30 wound around it in the conductive material 32. Next, the conductive material 32 is cured to form the superconducting coil 10 (step S14). After the above steps are completed, the process described in this flowchart will be terminated.

[0032] According to the manufacturing equipment and method for the superconducting coil 10 with the above configuration, it is possible to achieve a state in which the insulating material 33 is not applied to the inner circumference surface of the superconducting wire 30 in the coil radial direction 22, which is the back side as viewed from the coating equipment 71. It is also possible to omit the coating equipment 71 by using MgB2 wire that has been pre-coated with the insulating material 33 using separate equipment. However, if formed using separate equipment, there is a possibility that the wire may twist when winding the circular cross-section superconducting wire, and it may not be possible to form the current bypass circuit as intended. Therefore, as shown in this embodiment, it is preferable to adopt a manufacturing procedure in which the insulating material 33 is applied immediately before the MgB2 wire is wound onto the coil bobbin 11.

[0033] The coating position and amount applied by the coating equipment 71 are not particularly limited. By adjusting the spray direction and amount from the coating equipment 71, or by using a known method such as a mask for the superconducting wire 30, the insulating material 33 can be selectively applied to only the outer circumference in the coil radial direction 22 or only in the axial direction 24, thereby forming the insulating material 33 at a desired position and thickness.

[0034] With the manufacturing equipment and method described above, the superconducting coil 10 allows for electrical conductivity between exposed areas 31 of the superconducting wire 30 where the insulating material 33 is not applied, via the conductive material 32, thereby securing a current path that bypasses the affected area when a normal conduction transition occurs. Furthermore, the current bypass circuit can be arbitrarily set by the area where the insulating material 33 is applied. For example, as shown in Figure 2 above, if the insulating material 33 is formed only on the outer circumference in the coil radial direction 22 and in the axial direction 24 of the superconducting wire 30, the current bypass circuit is limited to between the rows within the winding. In this way, the superconducting coil 10 can control the inter-wire resistance of the superconducting wire 30 by the area where the insulating material 33 is applied, thereby suppressing excitation delay time and the occurrence of hot spots.

[0035] [Another method for manufacturing superconducting coils] [Alternative manufacturing methods] Next, another form of the manufacturing method for the superconducting coil 10 will be described. Figure 5 shows the arrangement of the manufacturing equipment for the superconducting coil 10. The manufacturing equipment for the superconducting coil 10 shown in Figure 5 differs from the manufacturing equipment shown in Figure 3 above only in the placement of the insulating material 33 coating equipment 71; the arrangement of all other equipment is the same. The coating equipment 71 is positioned on the outer circumference of the coil bobbin 11 so as to be movable in the circumferential direction 23. The spray device of the coating equipment 71 sprays insulating material 33 toward the coil bobbin 11. The coating equipment 71 sprays insulating material 33 toward the superconducting wire 30 wound around the coil bobbin 11. The coating equipment 71 coats the insulating material 33 onto the superconducting wire 30 wound around the coil bobbin 11 while moving along the outer circumference of the coil bobbin 11 in the circumferential direction 23.

[0036] Next, Figure 6 shows a flowchart of a different manufacturing method for the superconducting coil 10 using the manufacturing equipment for the superconducting coil 10. First, the superconducting wire 30 is fed from the feed bobbin 70 towards the coil bobbin 11 (step S20). Next, the superconducting wire 30 is wound onto the coil bobbin 11 by one layer (step S21). Next, the insulating material 33 is applied to the outer surface of the superconducting wire 30 wound on the coil bobbin 11 using the coating equipment 71 (step S22). Next, it is determined whether the superconducting wire 30 coated with insulating material 33 is the final layer of the superconducting coil 10 wound around the coil bobbin 11 (step S23). If the superconducting wire 30 is not the final layer (NO in step S23), the process returns to step S20. If the superconducting wire 30 is the final layer (YES in step S23), the conductive material 32 is filled between the wires of the superconducting wire 30 wound on the coil bobbin 11 (step S24). The filling of the conductive material 32 is carried out in the same manner as the manufacturing method shown in Figures 3 and 4 above. Next, the conductive material 32 is cured to form the superconducting coil 10 (step S25). After the above steps are completed, the process described in this flowchart will be terminated.

[0037] In the manufacturing method of the superconducting coil 10 of this embodiment, insulating material 33 is applied each time the superconducting wire 30 is wound onto the coil bobbin 11 for a predetermined number of layers (one layer in the above example). In this embodiment, the application of insulating material 33 may be done not only by spraying as in the embodiment shown in Figure 3 above, but also by applying it using a brush, roller, or the like. The manufacturing procedure of this embodiment can obtain the same effects as the manufacturing method shown in Figure 3 above. Furthermore, in the manufacturing method of this embodiment, the time required for the insulating material 33 to dry and set, which is required from the time the insulating material 33 is applied to the superconducting wire 30 until it is wound onto the coil bobbin 11 in the manufacturing method shown in Figure 3 above, is eliminated, making it possible to increase the winding speed.

[0038] <3. Second Embodiment of a Superconducting Coil> Next, a second embodiment of the superconducting coil will be described. Figure 7 shows the configuration of the superconducting coil of the second embodiment. The superconducting coil 20 shown in Figure 7 is an enlarged view of a part of the coil winding section in the cross-sectional view of line AA of the superconducting coil 10 shown in Figure 1. Note that the superconducting coil 20 shown in Figure 7 differs from the superconducting coil of the first embodiment described above only in the configuration of the superconducting wire and insulating material. For this reason, detailed explanations of the same configuration as the superconducting coil of the first embodiment described above will be omitted below.

[0039] The superconducting coil 20 shown in Figure 7 comprises a coil winding 34 consisting of superconducting wire 36 wound around a coil bobbin 11. The superconducting wire 36 has a rectangular cross-section in which the length in the axial direction 24 is greater than the length in the coil radial direction 22. In this technology, a rectangular shape also includes a shape with rounded corners, as shown in Figure 7. The superconducting wire 36 is wound in the circumferential direction 23, offset in the axial direction 24, from the central axis 21 side of the superconducting coil 20, i.e., the inner circumference side, and stacked flat in the coil radial direction 22. The shape of the wire applied to the superconducting coil 20, such as the superconducting wire 36, is not particularly limited.

[0040] The superconducting coil 20 has conductive material 32 filled between the wires of tightly wound superconducting wires 36. Furthermore, the superconducting coil 20 has a covered region where a portion of the surface of the superconducting wire 36 is covered with an insulating material 33. In addition to the region covered with the insulating material 33, the superconducting coil 20 also has an exposed region 35 where the surface of the superconducting wire 36 is exposed. That is, the superconducting wire 36 has a region covered with the insulating material 33 and an exposed region 35. The superconducting wire 36, except for the region covered with the insulating material 33, is in contact with the conductive material 32 or an adjacent superconducting wire 30.

[0041] In the superconducting coil 20 shown in Figure 7, insulating material 33 is formed on the outer circumference of the superconducting wire 36 in the coil radial direction 22 and in the axial direction 24 of the superconducting wire 36, while the inner circumference surface in the coil radial direction 22 is exposed. Therefore, in the superconducting coil 20, insulating material 33 is formed between adjacent superconducting wires 36 in the coil radial direction 22 and in the axial direction 24. Furthermore, the insulating material 33 is formed continuously on the surface of the superconducting wire 36, but is formed separately between adjacent superconducting wires 36. Furthermore, in the superconducting coil 20, adjacent superconducting wires 36 do not directly contact each other, but rather contact each other via an insulating material 33. In addition, in the superconducting coil 20, adjacent superconducting wires 36 are electrically connected at their exposed regions 35 where the insulating material 33 is not formed, via a conductive material 32 filled between the superconducting wires 36. Therefore, in the superconducting coil 20, no direct current bypass is formed between adjacent superconducting wires 36, and a current bypass is formed from the exposed regions 35 of the superconducting wires 36 via the conductive material 32. Furthermore, the region in which the insulating material 33 is formed on the superconducting wire 30 is not particularly limited. Furthermore, the superconducting coil 20 can be manufactured using the superconducting coil manufacturing equipment and manufacturing method shown in Figure 3-6 above.

[0042] In the superconducting coil 20 with the above configuration, the resistance of the current crossing between the superconducting wires 36 is suppressed by the insulating material 33 formed on the surface of the superconducting wires 36. Therefore, the superconducting coil 20 can adjust the resistance between the wires that would occur if the superconducting wires 36 were not insulated, and suppress the excitation delay. Furthermore, since the superconducting coil 20 has conductive material 32 filled between the superconducting wires 36, the exposed surface area 35 of the superconducting wires 30 can form a current bypass circuit between adjacent superconducting wires 36. Therefore, the superconducting coil 20 can suppress the generation of hot spots due to damage to the superconducting wires 30. Furthermore, the superconducting coil 20 can arbitrarily adjust the resistance of the current crossing between the superconducting wires 36 by adjusting the ratio of the area of ​​the insulating material 33 formed on the surface of the superconducting wires 36 to the area of ​​the exposed region 35. As a result, the superconducting coil 20 can increase the controllable range of inter-wire resistance, making it possible to achieve both hot spot avoidance and suppression of excitation delay.

[0043] <4. Third Embodiment of a Superconducting Coil> Next, a third embodiment of the superconducting coil will be described. Figure 8 shows the configuration of the superconducting coil of the third embodiment. The superconducting coil 40 shown in Figure 8 is an enlarged view of the entire AA cross-sectional view of the superconducting coil 10 shown in Figure 1, and a part of the coil winding section. Note that the superconducting coil 40 shown in Figure 8 differs from the superconducting coil of the first embodiment described above only in the configuration of the superconducting wire and insulating material. For this reason, detailed explanations of configurations similar to those of the superconducting coils of the first and second embodiments described above will be omitted below.

[0044] The superconducting coil 40 shown in Figure 8 comprises a coil winding 34 consisting of superconducting wire 36 wound around a coil bobbin 11. The coil winding 34 is constructed by winding the superconducting wire 36 in the circumferential direction 23, shifting in the axial direction 24, starting from the central axis 21 side of the superconducting coil 40, i.e., the inner circumference side, and stacking them flat in the coil radial direction 22. The superconducting wire 36 has the same configuration as the superconducting coil of the second embodiment described above, with a length in the axial direction 24 being greater than the length in the coil radial direction 22, and having a rectangular cross-section with rounded corners.

[0045] The superconducting coil 40 has insulating material 37 filled between the tightly wound superconducting wires 36. Examples of insulating material 37 include epoxy resin, phenoxy resin, and cyanoacrylate resin. Furthermore, the superconducting coil 40 has a covered region where a portion of the surface of the superconducting wire 36 is covered with a conductive material 38. In addition to the covered region of the conductive material 38, the superconducting coil 40 also has an exposed region 35 where the surface of the superconducting wire 36 is exposed. That is, the superconducting wire 36 has a region covered with the conductive material 38 and an exposed region 35. The superconducting wire 36, except for the covered region of the conductive material 38, is in contact with the insulating material 37. The conductive material 38 can be a conductive resin, a metal material, a conductive paste, etc. Preferably, the conductive material 38 is a metal material containing at least one of copper, zinc, and brass.

[0046] The conductive material 38 preferably has an uneven surface. The uneven surface preferably has a predetermined surface roughness. The dimensions of the surface irregularities of the conductive material 38 can be controlled by the setting conditions of the thermal spraying apparatus for the metal material, as described later. Increasing the dimensions of the surface irregularities of the conductive material 38 reduces the contact area with adjacent superconducting wires 36, thereby increasing the inter-wire resistance. Conversely, decreasing the dimensions of the surface irregularities of the conductive material 38 increases the contact area with adjacent superconducting wires 36, thereby decreasing the inter-wire resistance. In this way, by controlling the surface irregularities of the conductive material 38, the inter-wire resistance of the superconducting wires 36 can be adjusted, making it possible to achieve both hot spot avoidance and suppression of excitation delay.

[0047] In the superconducting coil 40 shown in Figure 8, a conductive material 38 is formed on the outer circumference of the superconducting wire 36 in the coil radial direction 22, and exposed regions 35 are formed on the inner circumference of the superconducting wire 36 in the axial direction 24 and in the coil radial direction 22. Therefore, in the superconducting coil 40, the conductive material 38 is formed between adjacent superconducting wires 36 in the coil radial direction 22. Furthermore, the conductive material 38 is formed continuously on the surface of the superconducting wire 36, but is formed separately between adjacent superconducting wires 36. Furthermore, in the superconducting coil 40, adjacent superconducting wires 36 do not directly contact each other in the coil radial direction 22, but are electrically connected via a conductive material 38. Also, in the superconducting coil 40, adjacent superconducting wires 36 in the axial direction 24 are in contact via an insulating material 37 filled between the superconducting wires 36. Therefore, in the superconducting coil 40, no direct current bypass is formed between adjacent superconducting wires 30, but a current bypass is formed in the coil radial direction 22 via the conductive material 38. In such a structure, since interlayer contact is dominant in the electrical contact between superconducting wires 36, the current bypass is mainly interlayer.

[0048] In the non-insulated coil method, the smaller the resistance between wires, the faster the current can bypass the normal conduction transition section. Therefore, in the superconducting coil 40, the inter-wire resistance of the superconducting coil 40 is reduced because the superconducting wire 36 is covered with a conductive material 38.

[0049] The region on the superconducting wire 36 where the conductive material 38 is formed is not particularly limited. For example, the superconducting wire 36 may have the conductive material 38 formed on the outer circumference in the coil radial direction 22 and on the axial direction 24, and an exposed region 35 formed on the inner circumference in the coil radial direction 22. Alternatively, the superconducting wire 36 may have the conductive material 38 formed only on the axial direction 24, and an exposed region 35 formed on the outer circumference and the inner circumference in the coil radial direction 22. Furthermore, the conductive material 38 does not have to be formed continuously on the surface of the superconducting wire 36. For example, the conductive material 38 may be formed separately on both sides of the axial direction 24 of the superconducting wire 36, or the conductive material 38 may be formed separately on the outer circumference and the inner circumference in the coil radial direction 22, respectively.

[0050] In the superconducting coil 40 with the above configuration, the insulating material 37 filled between the superconducting wires 36 suppresses the resistance of the current crossing the superconducting wires 36. Therefore, the superconducting coil 40 can adjust the resistance between the wires that occurs when the superconducting wires 36 are not insulated, and suppress the excitation delay. Furthermore, since the superconducting coil 40 has a conductive material 38 formed on the surface of the superconducting wire 36, a current bypass can be formed between adjacent superconducting wires 36 via the conductive material 38. Therefore, the superconducting coil 40 can suppress the generation of hot spots due to damage to the superconducting wire 36.

[0051] Furthermore, the superconducting coil 40 can arbitrarily adjust the resistance of current crossing between superconducting wires 36 by adjusting the ratio of the area of ​​the conductive material 38 formed on the surface of the superconducting wires 36 to the area of ​​the exposed region 35. By adjusting the position of the conductive material 38 formed on the superconducting coil 40, it is possible to create structures in which adjacent superconducting wires 36 come into contact with each other in the coil radial direction 22 or axial direction 24, or structures that restrict contact between superconducting wires 36. As a result, the superconducting coil 40 can arbitrarily adjust the resistance of current crossing between superconducting wires 36, thereby achieving both hot spot avoidance and suppression of excitation delay. In particular, the superconducting coil 40 can employ a configuration in which contact between superconducting wires 36 is prevented by an insulating material 37, and mainly only current bypass circuits are formed via the conductive material 38. By limiting the current bypass path via the conductive material 38 in this way, the superconducting coil 40 can more easily suppress excitation delay.

[0052] [Method for manufacturing superconducting coils] Next, the manufacturing method for the superconducting coil 40 described above will be explained. Figure 9 shows the arrangement of the manufacturing equipment for the superconducting coil 40. Note that the manufacturing equipment for the superconducting coil 40 shown in Figure 9 differs from the manufacturing equipment shown in Figure 3 above only in the configuration of the coating equipment; the arrangement of all other equipment is the same. For this reason, a detailed explanation of the configuration, which is the same as that of the manufacturing equipment for the superconducting coil 10 shown in Figure 3 above, will be omitted.

[0053] As shown in Figure 9, the manufacturing equipment for the superconducting coil 40 is arranged in the following order: a feed bobbin 70 for holding the superconducting wire 36, a coating equipment 72 for the conductive material 38, and a coil bobbin 11. The superconducting wire 36 fed from the feed bobbin 70 is coated with the conductive material 38 by the coating equipment 72. The superconducting wire 36 coated with the conductive material 38 is then wound onto the coil bobbin 11, and wound on the coil bobbin 11 while being shifted in the axial direction 24, and stacked flat in the coil radial direction 22.

[0054] The coating equipment 72 includes a spraying device for ejecting the conductive material 38. For example, if the conductive material 38 is a conductive resin, the coating equipment 72 may include a spraying device. Alternatively, if the conductive material is a metal such as copper, zinc, or brass, the coating equipment 72 may include a thermal spraying device. The coating equipment 72 is preferably a thermal spraying device. The thermal spraying device applies a thermal spraying material, which has been melted using a plasma or heater, to the target object by spraying it. Furthermore, the thermal spraying device can control the surface irregularities of the conductive material 38 by adjusting the particle size of the thermal spraying material. By controlling the surface irregularities of the conductive material 38, the contact area between the superconducting wires 36 via the conductive material 38 can be controlled.

[0055] Furthermore, when a conductive resin is used as the conductive material 38, a superconducting coil 40 can be manufactured by changing the material sprayed from the coating equipment 72 in the manufacturing equipment shown in Figures 3 and 5 above to the conductive material 38. However, because the thermal spraying equipment is large in size and weight, it is not practical to apply it to a configuration in which the coating equipment 72 moves circumferentially, such as the manufacturing equipment shown in Figure 5. For this reason, when using a metal material as the conductive material 38 and applying the manufacturing equipment shown in Figure 5, it is preferable to use a coating equipment 72 that can move circumferentially. Furthermore, the manufacturing method for the superconducting coil 40 using the manufacturing equipment can be the same as the flowcharts shown in Figures 4 and 6 above.

[0056] <5. Fourth Embodiment of a Superconducting Coil> Next, a fourth embodiment of the superconducting coil will be described. Figure 10 shows the configuration of the superconducting coil of the fourth embodiment. The superconducting coil 50 shown in Figure 10 is an enlarged view of a part of the coil winding section in the cross-sectional view of line AA of the superconducting coil 10 shown in Figure 1. Note that the superconducting coil 50 shown in Figure 10 differs from the superconducting coil of the third embodiment described above only in the configuration of the superconducting wire and insulating material. For this reason, detailed explanations of configurations similar to those of the superconducting coils of the first, second, and third embodiments described above will be omitted below.

[0057] The superconducting coil 50 shown in Figure 10 comprises a coil winding 34 consisting of superconducting wire 30 wound around a coil bobbin 11. The superconducting wire 30 has a circular cross-section. The superconducting wire 30 is wound in the circumferential direction 23, shifting in the axial direction 24, from the central axis 21 side of the superconducting coil 50, i.e., the inner circumference side, and is stacked in a barrel-like manner in the coil radial direction 22.

[0058] The superconducting coil 50 has insulating material 37 filled between the tightly wound superconducting wires 30. Furthermore, the superconducting coil 50 has a covered region where a portion of the surface of the superconducting wire 30 is covered with a conductive material 38. In addition, the superconducting coil 50 has an exposed region 31 where the surface of the superconducting wire 30 is exposed, separate from the covered region of the conductive material 38. That is, the superconducting coil 50 has a covered region of the conductive material 38 and an exposed region 31. The superconducting wire 30, except for the covered region of the conductive material 38, is in contact with the insulating material 37 or with an adjacent superconducting wire 30. Furthermore, it is preferable that the conductive material 38 has an uneven surface. By controlling the uneven surface of the conductive material 38, the inter-wire resistance of the superconducting wire 30 can be adjusted, making it possible to achieve both hot spot avoidance and suppression of excitation delay. The superconducting coil 50 is made of the same materials as in the third embodiment described above, as the insulating material 37 and the conductive material 38.

[0059] In the superconducting coil 50 shown in Figure 10, conductive material 38 is formed on the outer circumference of the superconducting wire 30 in the coil radial direction 22 and in the axial direction 24 of the superconducting wire 30, and an exposed region 31 is formed on the inner circumference in the coil radial direction 22. Therefore, in the superconducting coil 50, conductive material 38 is formed between adjacent superconducting wires 30 in the coil radial direction 22 and in the axial direction 24. Furthermore, the conductive material 38 is formed continuously on the surface of the superconducting wire 30, but is formed separately between adjacent superconducting wires 30. Furthermore, in the superconducting coil 50, adjacent superconducting wires 30 do not directly contact each other, but are electrically connected via a conductive material 38. Also, in the superconducting coil 50, adjacent superconducting wires 30 are in contact via an insulating material 37 filled between the superconducting wires 30. Therefore, in the superconducting coil 10, a current bypass is not directly formed between adjacent superconducting wires 30, but a current bypass is formed via the conductive material 38. In the non-insulated coil method, the smaller the resistance between wires, the faster the current can bypass the normal conduction transition section. Therefore, in the superconducting coil 50, the inter-wire resistance of the superconducting coil 50 is reduced by coating the superconducting wire 30 with a conductive material 38.

[0060] The region on the superconducting wire 30 where the conductive material 38 is formed is not particularly limited. For example, the superconducting wire 30 may have the conductive material 38 formed only on the outer circumference in the coil radial direction 22, with exposed regions 35 formed on the inner circumference in the coil radial direction 22 and in the axial direction 24. Alternatively, the superconducting wire 30 may have the conductive material 38 formed only in the axial direction 24, with exposed regions 35 formed on both the outer and inner circumferences in the coil radial direction 22. Furthermore, the conductive material 38 does not have to be formed continuously on the surface of the superconducting wire 30. For example, the conductive material 38 may be formed separately on both sides of the axial direction 24 of the superconducting wire 30, or the conductive material 38 may be formed separately on the outer circumference and inner circumference in the coil radial direction 22, respectively.

[0061] In the superconducting coil 50 with the above configuration, the insulating material 37 filled between the superconducting wires 30 suppresses the current that crosses the superconducting wires 30. Therefore, the superconducting coil 50 can adjust the resistance between the wires that would result from the lack of insulation in the superconducting wires 30, and suppress the excitation delay. Furthermore, the superconducting coil 50 has a conductive material 38 formed on the surface of the superconducting wire 30. As a result, the superconducting coil 50 forms a current bypass circuit between adjacent superconducting wires 30 via the conductive material 38. Consequently, the superconducting coil 50 can suppress the generation of hot spots due to damage to the superconducting wire 30.

[0062] Furthermore, the superconducting coil 50 can arbitrarily adjust the resistance of current crossing between superconducting wires 30 by adjusting the ratio of the area of ​​the conductive material 38 formed on the surface of the superconducting wires 30 to the area of ​​the exposed region 31. In addition, by adjusting the position of the conductive material 38, the superconducting coil 50 can be configured to have structures that bring adjacent superconducting wires 30 into contact with each other in the coil radial direction 22 or axial direction 24, or structures that restrict contact between superconducting wires 30. As a result, the superconducting coil 50 can arbitrarily adjust the resistance of current crossing between superconducting wires 30, making it possible to avoid hot spots and suppress excitation delay at the same time. In particular, the superconducting coil 50 can employ a configuration in which contact between the superconducting wires 30 is prevented by an insulating material 37, and mainly only a current bypass circuit is formed via the conductive material 38. By limiting the current bypass path via the conductive material 38 in this way, the superconducting coil 50 can more easily suppress excitation delay.

[0063] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are possible. For example, the embodiments described above are explained in detail to make the present invention easier to understand, and the present invention is not necessarily limited to embodiments that have all the described configurations. Furthermore, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment. It is also possible to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to delete or add / replace parts of the configuration of each embodiment. [Explanation of Symbols]

[0064] 10, 20, 40, 50 Superconducting coil, 11 Coil bobbin, 21 Central axis, 22 Coil radial direction, 23 Circumferential direction, 24 Axial direction, 30, 36 Superconducting wire, 31, 35 Exposed area, 32 Conductive material, 33, 37 Insulating material, 34 Coil winding, 38 Conductive material, 51, 52 Insulating material, 53 Cooling plate, 70 Feed bobbin, 71, 72 Coating equipment

Claims

1. A superconducting coil in which superconducting wire is wound, The superconducting wire is wound from the inner circumference of the superconducting coil, offset in the axial direction of the superconducting coil, and stacked radially in the superconducting coil, A conductive material filled between the wound superconducting wires, The superconducting wire comprises a coating region of an insulating material formed on its surface, The superconducting wire has an exposed region in which the surface of the superconducting wire is exposed outside of the covered region. Superconducting coil.

2. The superconducting wire has at least the exposed region on the inner circumference side in the radial direction of the superconducting coil of the superconducting wire. The superconducting coil according to claim 1.

3. The superconducting wire has the covering region at least on the radial outer circumference side of the superconducting coil of the superconducting wire. The superconducting coil according to claim 1.

4. The superconducting wire has a circular or rectangular cross-section. The superconducting coil according to claim 1.

5. A superconducting coil in which superconducting wire is wound, The superconducting wire is wound from the inner circumference of the superconducting coil, offset in the axial direction of the superconducting coil, and stacked radially in the superconducting coil, An insulating material filled between the wound superconducting wires, The superconducting wire comprises a coating region of a conductive material formed on its surface, The superconducting wire has an exposed region in which the surface of the superconducting wire is exposed outside of the covered region. Superconducting coil.

6. The superconducting wire has at least the exposed region on the inner circumference side in the radial direction of the superconducting coil of the superconducting wire. The superconducting coil according to claim 5.

7. The superconducting wire has the covering region at least on the radial outer circumference side of the superconducting coil of the superconducting wire. The superconducting coil according to claim 5.

8. The superconducting wire has a circular or rectangular cross-section. The superconducting coil according to claim 5.

9. The conductive material includes one or more selected from copper, zinc, and brass. The superconducting coil according to claim 5.

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