Manufacturing method of uninsulated superconducting coil and uninsulated superconducting coil

Abstract

The invention relates to the technical field of nuclear fusion, and provides a manufacturing method of an uninsulated superconducting coil and the uninsulated superconducting coil, and the manufacturing method comprises the steps that a metal strip and a superconducting strip are stacked and wound to form a coil with a preset number of turns, a wound coil is obtained, and the width of the metal strip is larger than that of the superconducting strip; the wound coil is placed in a soldering tin dipping device to be subjected to soldering tin dipping, and a welded coil is obtained; and removing the soldering tin shell on the annular surface of the welding coil until the metal strip is exposed. The superconducting strip and the metal strip with the width larger than that of the superconducting strip are overlapped, wound and welded, so that the mechanical stability of the uninsulated superconducting coil is improved, meanwhile, the cold conduction effect is enhanced, then the soldering tin shell is removed till the metal strip is exposed, the superconducting strip cannot be damaged when the soldering tin shell is removed, and the production efficiency is improved. The performance of the uninsulated superconducting coil can be guaranteed, the metal strip can be completely separated from the superconducting strip of the adjacent turns, and the inter-turn resistivity is further improved.

Description

Technical Field

[0001] The present application relates to the field of nuclear fusion technology, and in particular to a method for manufacturing a non-insulated superconducting coil and a non-insulated superconducting coil. Background Art

[0002] Uninsulated superconducting coils are coils wound with superconducting tapes and without organic insulation between turns. Compared with traditional insulated coils, uninsulated superconducting coils have more compact structures, stronger mechanical and cooling performance, and can provide higher magnetic field strength and other characteristics, and have a wider range of application scenarios. Therefore, the mechanical properties, cooling performance and inter-turn resistivity of uninsulated superconducting coils often have a significant impact on uninsulated coils.

[0003] The turn-to-turn resistivity of existing uninsulated superconducting coils is often small, which leads to a large time constant in the charging and discharging process of the uninsulated superconducting coils. At the same time, some uninsulated coils often have poor mechanical properties and cooling performance. Therefore, how to provide sufficient mechanical stability for the uninsulated superconducting coils while maximizing the turn-to-turn resistance of the coils and increasing the cooling performance to improve the comprehensive performance of the uninsulated superconducting coils has become a technical problem that needs to be solved urgently. Summary of the invention

[0004] In view of this, the present application provides a method for manufacturing an uninsulated superconducting coil and an uninsulated superconducting coil to solve the technical problem of how to provide sufficient mechanical stability for the uninsulated coil while maximizing the inter-turn resistance of the coil and increasing the cooling performance to improve the comprehensive performance of the uninsulated superconducting coil.

[0005] According to the first aspect, an embodiment of the present application provides a method for manufacturing an uninsulated superconducting coil, comprising: overlapping a superconducting tape and a metal tape having a width greater than that of the superconducting tape, and winding them together, and winding a predetermined number of turns to obtain a wound coil; after obtaining the wound coil, welding the wound coil using a solder dipping device, so that the solder fills the gap between the metal tape and the superconducting tape, and forms a welding layer in the gap between the metal tape and the superconducting tape, to obtain a welded coil; after welding is completed, removing the solder shell located on the annular surface of the welded coil until the metal tape is exposed, to obtain an uninsulated superconducting coil.

[0006] In one embodiment, during the winding process of the metal tape and the superconducting tape, when the metal tape and the superconducting tape intersect, the superconducting tape and the metal tape are arranged in a staggered manner so that they can be arranged in a concave and convex manner on the annular surface of at least one side of the winding coil after intersecting, overlapping and winding.

[0007] In one embodiment, the solder shell on one side of the concave-convex alternating arrangement is polished so that the polished surface exposes the metal strip, and the metal strip separates the solder shells on the superconducting tape of adjacent turns.

[0008] In one embodiment, the metal tape and the superconducting tape are tinned before being wound together.

[0009] In one embodiment, the solder dipping device includes a forced convection heating box, a dipping mold arranged in the forced convection heating box, a first solder can, a second solder can, and an air circuit component; wherein the dipping mold includes a accommodating cavity for winding a coil and a first connecting port and a second connecting port connected to the accommodating cavity, the first solder can has a first air circuit port and a first solder filling port, the first air circuit port is connected to the air circuit component, and the first solder filling port is connected to the first connecting port; the second solder can has a second air circuit port and a second solder filling port, the second air circuit port is connected to the air circuit component, and the second solder filling port is connected to the first connecting port. The filling port is connected with the second connecting port; when the wound coil is dipped in solder, the wound coil is placed in the dipping mold, and the forced convection heating box heats the solder into liquid solder; under the gas pressure provided by the gas path component, the liquid solder flows out from one of the first solder tank and the second solder tank, flows through the accommodating cavity of the dipping mold to dip the wound coil, and then flows into the other solder tank of the first solder tank and the second solder tank; the heating is stopped, the liquid solder is cooled into solid solder, the dipping mold is removed, the solder dipping of the wound coil is completed, and the welded coil is obtained.

[0010] According to the second aspect, an embodiment of the present application provides an uninsulated superconducting coil, comprising: a wound coil, having a metal tape and a superconducting tape with a preset number of turns, the width of the metal tape being greater than the width of the superconducting tape; the metal tape and the superconducting tape being arranged alternately in convex and concave on an annular surface on at least one side of the wound coil; and a welding layer filled between the metal tape and the superconducting tape.

[0011] In one embodiment, the metal tape separates adjacent turns of the superconducting tape.

[0012] In one embodiment, the width of the metal tape is 1.1 to 1.5 times the width of the superconducting tape.

[0013] In one embodiment, the metal strip comprises a brass strip or a stainless steel strip.

[0014] This application has at least the following beneficial effects:

[0015] In the present application, a superconducting tape and a metal tape having a width greater than that of the superconducting tape are overlapped and wound, and the wound coil is welded by a solder dipping process, so that a welding layer is formed in the gap between the metal tape and the superconducting tape to enhance the inter-turn bonding ability of the non-insulated superconducting coil and the mechanical stability of the non-insulated superconducting coil. At the same time, by welding the metal tape between the turns, the heat capacity of the non-insulated superconducting coil can be increased, the cooling channel can be increased, and the cooling effect can be enhanced. Then, the solder shell located on the annular surface of the welded coil is removed to expose the metal tape. Since the width of the metal tape is greater than the width of the superconducting tape, the superconducting tape will not be damaged when the solder shell is removed, and the performance of the non-insulated superconducting coil can be guaranteed. After removing the solder shell, the metal tape can completely separate the solder shells on the superconducting tapes of adjacent turns, and prevent the problem of reduced inter-turn resistivity caused by indirect contact between the superconducting tapes of adjacent turns through solder, so that a non-insulated superconducting coil with strong mechanical properties, good cooling effect and high inter-turn resistivity can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 It is a schematic flow chart of a method for manufacturing a non-insulated superconducting coil according to an embodiment of the present application;

[0018] Figure 2 A schematic structural diagram of a winding machine for a non-insulated superconducting coil provided according to an embodiment of the present application;

[0019] Figure 3 A schematic cross-sectional structure diagram of a non-insulated superconducting coil provided according to an embodiment of the present application;

[0020] Figure 4 A schematic diagram of a cross-sectional structure of another non-insulated superconducting coil provided according to an embodiment of the present application;

[0021] Figure 5 A schematic cross-sectional structure diagram of a non-insulated superconducting coil with a coil skeleton provided according to an embodiment of the present application;

[0022] Figure 6 A schematic diagram of the structure of a solder dipping device provided according to an embodiment of the present application;

[0023] Figure 7 It is a schematic diagram of the cross-sectional structure of a non-insulated superconducting coil impregnated with solder;

[0024] Figure 8 It is a schematic diagram of the cross-sectional structure of a non-insulated superconducting coil welded by brazing;

[0025] Fig. 9 yes Figure 4 , Figure 7 and Figure 8 Schematic diagram of the inter-turn resistivity test results of three types of uninsulated superconducting coils. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of this application.

[0027] The present application provides a method for manufacturing a non-insulated superconducting coil, such as Figures 1 to 6 As shown, the following steps S101 to S103 are included:

[0028] S101. Overlap a superconducting tape and a metal tape having a width greater than that of the superconducting tape and wind them together, and obtain a winding coil by winding a predetermined number of turns.

[0029] In this embodiment, a superconducting tape 1 and a metal tape 2 having a width greater than that of the superconducting tape 1 can be overlapped and wound together, and a predetermined number of turns can be wound to obtain a winding coil. The structure of the winding coil is that the metal tape 2 is wound between adjacent turns of the winding of the superconducting tape 1.

[0030] In this embodiment, Figure 2 The winding machine shown in the figure is used for winding. The winding machine includes two pay-off reels 6, one of which carries a metal tape 2 and the other carries a superconducting tape 1. The metal tape 2 and the superconducting tape 1 are converged and overlapped after passing through a plurality of wire wheels 8 and are wound on a take-up reel 7. After reaching a predetermined number of turns, a winding coil is obtained. It should be noted that Figure 2 The winding machine shown is only exemplary, and similar or other types of winding machines may also be used as long as the technical solution of the present application can be implemented.

[0031] S102. After obtaining the wound coil, the wound coil is welded by a solder dipping device, so that the solder fills the gap between the metal strip and the superconducting tape, and forms a welding layer in the gap between the metal strip and the superconducting tape to obtain a welded coil. The metal strip 2 and the superconducting tape 1 are welded together to enhance the inter-turn bonding ability of the non-insulated superconducting coil and enhance the mechanical stability of the non-insulated superconducting coil. At the same time, by welding the metal strip 2 between the turns, the heat capacity of the non-insulated superconducting coil can be increased, the cooling channel can be increased, and the cooling effect can be enhanced.

[0032] S103. After welding is completed, the solder shell on the annular surface of the welding coil is removed until the metal strip is exposed to obtain a non-insulated superconducting coil. After the solder dipping is completed, a solder shell 31 will be formed on the outer layer of the welding coil, and the solder shell 31 connects the adjacent turns of the superconducting tape 1 together. The inter-turn resistivity of the non-insulated superconducting coil is small, resulting in a large time constant of the coil during the charging and discharging process. Therefore, in this embodiment, after the dipping is completed, the solder shell 31 on the annular surface of the welding coil is removed until the metal strip 2 is exposed. Since the width of the metal strip 2 is greater than the width of the superconducting tape 1, the superconducting tape 1 will not be damaged when the solder shell 31 is removed, and the performance of the non-insulated superconducting coil can be guaranteed. After removing the solder shell 31, the metal strip 2 can completely separate the solder shell 31 on the adjacent turns of the superconducting tape 1, preventing the problem of reduced inter-turn resistivity caused by indirect contact between adjacent turns of the superconducting tape 1 through solder.

[0033] In the present application, a superconducting tape 1 and a metal tape 2 having a width greater than that of the superconducting tape 1 are overlapped and wound, and the wound coils are welded by a solder dipping process, and a welding layer 3 is formed in the gap between the metal tape 2 and the superconducting tape 1 to enhance the inter-turn bonding ability of the non-insulated superconducting coil and the mechanical stability of the non-insulated superconducting coil. At the same time, by welding the metal tape 2 between the turns, the heat capacity of the non-insulated superconducting coil can be increased, the cooling channel can be increased, and the cooling effect can be enhanced. Then, the outer surface of the solder located on the annular surface of the welded coil is covered with a solder paste. The shell 31 is removed until the metal tape 2 is exposed. Since the width of the metal tape 2 is greater than the width of the superconducting tape 1, the superconducting tape 1 will not be damaged when the solder shell 31 is removed, thereby ensuring the performance of the non-insulated superconducting coil. After the solder shell 31 is removed, the metal tape 2 can completely separate the solder shells 31 on the adjacent turns of the superconducting tape 1, thereby preventing the problem of reduced inter-turn resistivity caused by indirect contact between adjacent turns of the superconducting tape 1 through solder, thereby obtaining a non-insulated superconducting coil with strong mechanical properties, good cooling effect and high inter-turn resistivity.

[0034] In one embodiment, the void ratio of the welding layer 3 between the metal strip 2 and the superconducting tape 1 seriously affects the cooling performance of the coil. Therefore, in order to reduce the void ratio of the welding layer 3 and enhance the cooling performance of the coil, in this embodiment, the metal strip 2 and the superconducting tape 1 are tinned to enhance the solder wetting effect of the metal strip 2 and the superconducting tape 1 and reduce the void ratio. Further, in order to reduce the void ratio caused by oxidation during the solder dipping process, the flux is applied before the wound coil is soldered. And the dipping mold is vacuumed using a vacuum pump before solder dipping.

[0035] During the winding process of the metal tape 2 and the superconducting tape 1, the metal tape 2 and the superconducting tape 1 are arranged alternately in concave and convex shapes on at least one side of the annular surfaces on both sides of the winding coil.

[0036] In one embodiment, during the winding process of the metal tape 2 and the superconducting tape 1, the metal tape 2 and the superconducting tape 1 are arranged flush on the annular surface on one side formed by the winding coil, and arranged alternately in concave and convex shapes on the annular surface on the other side. Figure 3 The structure of the uninsulated superconducting coil is shown.

[0037] During the winding process, an alignment base can be provided on the take-up reel 7. During the parallel winding process, the superconducting tape 1 and the metal tape 2 are aligned on the alignment base on the annular surface facing one side of the alignment base, and the superconducting tape 1 and the metal tape 2 are arranged alternately in concave and convex shapes on the annular surface on the other side. After the parallel winding is completed, the side where the metal tape 2 and the superconducting tape 1 are arranged flush with each other in the winding coil is subjected to solder rejection treatment. For example, a high temperature resistant tape can be applied to the metal tape 2 and the superconducting tape 1 on the side where the metal tape 2 and the superconducting tape 1 are arranged flush with each other. Then, solder dipping is performed. After solder dipping, a solder shell 31 is formed only on the side where the concave and convex shapes are arranged alternately in the winding coil. After removing the solder shell 31, a non-insulated superconducting coil is obtained.

[0038] In another embodiment, two coils can be wound together. For example, a coil skeleton 4 can be installed on the winding reel 7, and a dividing plate 5 perpendicular to the axis of the coil skeleton 4 is installed in the middle of the coil skeleton 4. The two coils are respectively wound on both sides of the dividing plate 5. During the winding process of the coils, the dividing plate 5 is used as an alignment base to align the metal strip 2 and the superconducting tape 1 on the dividing plate 5. In this way, the metal strip 2 and the superconducting tape 1 are arranged flush on the side facing the dividing plate 5, and are arranged in a concave-convex pattern on the side away from the dividing plate 5. When solder dipping is performed, the dipping can be performed together with the coil skeleton 4 and the dividing plate 5 or together with the dividing plate 5, wherein the dividing plate 5 and the coil skeleton 4 can be made of ceramic materials that cannot be wetted by solder. After the dipping is completed, a welded coil can be obtained in which a solder shell 31 is formed only on one side of the wound coil with a concave-convex pattern. After removing the solder shell 31, a non-insulated coil can be obtained. See also Figure 4The structure of the uninsulated superconducting coil is shown.

[0039] In order to increase the isolation effect of the metal tape 2 on the superconducting tape 1 and further improve the inter-turn resistivity of the uninsulated superconducting coil, see Figure 5 In the structure of the uninsulated superconducting coil shown, the metal tape 2 and the superconducting tape 1 are arranged alternately in concave and convex shapes on the annular surfaces on both sides formed by the winding coil.

[0040] In order to realize that the metal strip 2 and the superconducting tape 1 are arranged alternately in concave and convex on the annular surfaces on both sides formed by the winding coil, the metal strip 2 and the superconducting tape 1 can be tinned first, and then the metal strip 2 and the superconducting tape 1 are tinned. Figure 2 When the winding machine shown is performing winding, the positions of the wire wheels 8 of the metal tape 2 and the superconducting tape 1 are adjusted respectively. When the metal tape 2 and the superconducting tape 1 intersect, the superconducting tape 1 is located in the middle of the metal tape 2, so that after the intersection, overlap and parallel winding, a concave and convex alternating arrangement can be formed on both sides of the coil.

[0041] Furthermore, in the process of winding, using Figure 2 When the winding machine shown is winding, a heating device can be set at the intersection of the metal belt 2 and the superconducting tape 1 to heat and melt the solder on the metal belt 2 and the superconducting tape 1, and then cool it. After the superconducting tape 1 and the metal belt 2 are pre-fixed, the winding is carried out. After the winding is completed, the coil is fixed, and then the solder is dipped. In this way, the metal belt 2 and the superconducting tape 1 are arranged alternately in concave and convex on the annular surface of the coil. Since the superconducting tape 1 and the metal belt 2 on both sides of the coil are arranged alternately in concave and convex, when removing the solder shell 31, for example, when removing it by grinding, since the metal belt 2 is closer to the outside, the superconducting tape 1 will not be damaged when grinding the solder shell 31, and the solder between the adjacent turns of the superconducting tape 1 can be completely removed, so that the isolation effect of the metal belt 2 on the superconducting tape 1 is more thorough, the inter-turn resistivity is larger, and it is more stable.

[0042] When solder dipping, use Figure 6The solder dipping device shown in the figure performs solder dipping, wherein the solder dipping device comprises a forced convection heating box 100 and a solder pot 200 and a dipping mold 300 arranged in the forced convection heating box 100. When the winding coil is dipped in solder, the winding coil is placed in the dipping mold 300, and the forced convection heating box 100 is used to heat the solder pot 200 and the dipping mold 300, so that the solder in the solder pot 200 enters the dipping mold 300 to perform solder dipping on the winding coil. In this embodiment, the use of the forced convection heating box 100 to heat the dipping mold 300 can ensure that the dipping mold 300 and the winding coil placed in the dipping mold 300 can be fully and evenly heated, so as to ensure that the liquid solder can fully flow in the dipping mold 300, fill the gaps of the winding coil, and reduce the void rate of the welding layer 3.

[0043] In an optional embodiment, the solder dipping device may further include an air circuit component 400 to provide a positive pressure air source; the dipping mold 300 may include a accommodating cavity 310 for winding a coil and a first connecting port 320 and a second connecting port 330 connected to the accommodating cavity 310; the solder tank 200 may include a first solder tank 210 and a second solder tank 220, wherein the first solder tank 210 has a first air circuit port 211 and a first solder filling port 212, the first air circuit port 211 is connected to the air circuit component 400, and the first solder filling port 212 is connected to the first connecting port 320; the second solder tank 220 It has a second gas path port 221 and a second solder filling port 222, the second gas path port 221 is connected to the gas path component 400, and the second solder filling port 222 is connected to the second connecting port 330; the forced convection heating box 100 heats the solder into liquid solder; under the gas pressure provided by the gas path component 400, the liquid solder flows out from one of the first solder tank 210 and the second solder tank 220, flows through the accommodating cavity 310 of the dipping mold 300 to dip the wound coil, and then flows into the other solder tank of the first solder tank 210 and the second solder tank 220.

[0044] During the process of dipping the coil, the gas circuit component 400 can be closed and opened in time with the connection with the first gas circuit port 211 and the second gas circuit port 221. Exemplarily, during one dipping process, the gas circuit component 400 opens the connection with the first gas circuit port 211 and closes the connection with the second gas circuit port 221. The gas circuit component 400 applies gas pressure and the dead weight of the liquid solder, and the liquid solder in the first solder tank 210 flows into the dipping mold 300 from the first solder filling port 212 and the first connecting port 320 to fill the wound coil and the gap between the coils. After the dipping mold 300 is filled, it flows out from the second connecting port 330 and flows into the second solder tank 220 through the second solder filling port 222 to ensure that the solder can fill the entire dipping mold 300, while preventing the solder from splashing and overflowing, and the solder in the second solder tank 220 is directly recycled and reused during the next dipping process. The dipping mold 300 is kept under pressure for a period of time to ensure that the liquid solder is fully impregnated into the interlayer gap of the winding coil, so that the winding coil can be fully impregnated with the solder, further reducing the porosity of the welding layer 3.

[0045] After that, the heating is stopped, the liquid solder is cooled to become solid solder, the dipping mold 300 is removed, and the solder dipping of the wound coil is completed to obtain the welded coil.

[0046] The present application also provides a non-insulated superconducting coil, such as Figure 3 As shown, the uninsulated superconducting coil includes a winding coil with a predetermined number of turns formed by winding a metal tape 2 and a superconducting tape 1; a welding layer 3 formed by solder is filled between the metal tape 2 and the superconducting tape 1 of the winding coil; wherein the width of the metal tape 2 is greater than the width of the superconducting tape 1, and the metal tape 2 and the superconducting tape 1 are arranged alternately in convex and concave shapes on the annular surface of at least one side of the winding coil.

[0047] In this embodiment, the inter-turn resistance of the superconducting tape 1 in the non-insulated superconducting coil can be increased by winding the metal tape 2 and the superconducting tape 1 in parallel, thereby reducing the time constant of the non-insulated superconducting coil during the charging and discharging process. At the same time, the gap between the metal tape 2 and the superconducting tape 1 is filled with solder, and the formed welding layer 3 welds the metal tape 2 and the superconducting tape 1 together, thereby enhancing the inter-turn bonding ability of the non-insulated superconducting coil and enhancing the mechanical stability of the non-insulated superconducting coil. At the same time, by welding the metal tape 2 in parallel between the turns, the heat capacity of the non-insulated superconducting coil can be increased, the cooling channel is increased, and the cooling effect is enhanced. In addition, the width of the metal tape 2 is greater than the width of the superconducting tape 1, and the metal tape 2 can better isolate the superconducting tapes 1 of adjacent turns, prevent direct or indirect contact between the superconducting tapes 1, so that the inter-turn resistivity fluctuation range is low, and the overall Joule thermal stability of the non-insulated superconducting coil is also greatly enhanced.

[0048] In one embodiment, in order to reduce the gap between the metal strip 2 and the tape, enhance the overall cooling performance and mechanical strength of the uninsulated superconducting coil, and stabilize the inter-turn resistivity, a metal solder is used to form a welding layer 3 to fill the gap between the metal strip 2 and the superconducting tape 1, thereby reducing the solder cavity between the metal strip 2 and the superconducting tape 1. The metal solder dipping method enables the metal solder to form a solder shell 31 on the surface of the superconducting tape 1 winding, and since the width of the metal strip 2 is greater than the width of the superconducting tape 1, after welding, see Figures 3 to 5 In the non-insulated superconducting coil shown, the metal tape 2 separates the solder shells 31 on the superconducting tapes 1 of adjacent turns, thereby preventing the problem of lowering the inter-turn resistivity due to indirect contact between the superconducting tapes 1 of adjacent turns through the metal solder.

[0049] In one embodiment, the width of the metal strip 2 is 1.1 to 1.5 times the width of the superconducting strip 1. For example, taking a strip with a width of 4.0 mm and a strip with a width of 4.5 mm as examples, the width of the metal strip 2 may be 5.0 mm. In an optional embodiment, the specific value of the width of the metal strip 2 may be determined according to actual conditions.

[0050] In one embodiment, the metal strip 2 can be selected from copper strip, brass strip and stainless steel strip. Brass is an alloy of copper and zinc, and its resistivity is relatively high, which is 7.1×10 -8 Ω·m, 4.66×10 at 77K -8 Ω·m; in contrast, copper is pure copper, so its resistivity is lower than that of brass, which is 1.76×10 at 20℃. -8 Ω·m, 2.44×10 at 77K -9 Ω·m. The resistivity of stainless steel is 5.4-5.88×10 at 77K. -7 Ω·m.

[0051] The time constant of the superconducting coil during the charging and discharging process is: τ=L / Rc, where τ is the time constant, L is the coil inductance, and Rc is the turn-to-turn resistance. It can be seen that in order to reduce the time constant of the coil during the charging and discharging process, the turn-to-turn resistance needs to be increased as much as possible. Therefore, in this embodiment, the metal belt 2 can be made of brass or stainless steel.

[0052] In another embodiment, since the tensile strength and elastic modulus of stainless steel are both high, the use of stainless steel strips and windings can provide the uninsulated superconducting coil with good stable mechanical properties of anti-expansion force. However, the wettability of metal solder to stainless steel is poor, and cavities are easily formed in the welding layer 3, which reduces the cooling effect of the uninsulated superconducting coil. Therefore, in this embodiment, a stainless steel strip coated or wrapped with brass can be used as the metal strip 2 and wound with the superconducting tape 1, so as to provide greater mechanical strength and greater inter-turn resistivity while minimizing the formation of cavities in the welding layer 3, thereby improving the cooling effect of the coil.

[0053] See also Figures 3 to 5 The schematic diagram of the non-insulated superconducting coil in the present application is shown as well as Figure 7 and Figure 8 The inter-turn resistivity of the non-insulated superconducting coil without the metal tape 2 is compared, where: Figure 7 A schematic diagram of an uninsulated superconducting coil dipped in solder is shown. Figure 8 The schematic diagram of the uninsulated superconducting coil welded by brazing is shown. Fig. 9 Shown Figure 7 The coil shown is 1#, Figure 8 The coil shown is 2#, Figure 4 The coil shown is the test result of the inter-turn resistivity of three types of non-insulated superconducting coils as 3#. It can be seen that the inter-turn resistivity of the non-insulated superconducting coil in the present application is larger and more stable.

[0054] Specifically, Figure 7 The schematic diagram of the uninsulated superconducting coil using solder dipping is shown. The solder is filled between the superconducting tapes 1 and forms a solder shell 31 on the surface of the winding of the superconducting tape 1. After testing, the inter-turn resistivity of the coil is 0.43μΩ·cm 2 The inter-turn resistivity is small, and the time constant of the uninsulated superconducting coil during the charging and discharging process reaches 2090s.

[0055] like Figure 8 The schematic diagram of the brazed uninsulated superconducting coil is shown. The brazed uninsulated superconducting coil welds adjacent layers of superconducting tapes 1 together by direct heating without adding solder. According to the test, the turn-to-turn resistivity of the uninsulated superconducting coil can reach 1.39μΩ·cm 2Compared with the solder-impregnated coil, the turn-to-turn resistance of the brazed uninsulated superconducting coil is significantly increased, and the time constant of the uninsulated superconducting coil during the charging and discharging process is reduced to 658s. However, after many tests, the turn-to-turn resistance of the brazed uninsulated superconducting coil is unstable, and the Joule heat of the uninsulated superconducting coil is unstable during the charging and discharging process. Studies have found that during the brazing process, since no additional solder is added, irregular tin spots will exist at the end of the uninsulated superconducting coil due to the melting of the solder, resulting in unstable turn-to-turn resistance; at the same time, since no additional tin is added, cavities will exist in the welding layer 3 between the superconducting tapes 1, which will increase the turn-to-turn resistivity of the brazed uninsulated superconducting coil. At the same time, the cavity of the welding layer 3 will also seriously affect the overall cooling performance of the uninsulated superconducting coil, making the coil Joule heat unstable during the charging and discharging process.

[0056] like Figures 3 to 5 As shown, the non-insulated superconducting coil welded and wound with the metal strip 2 of the present application is separated from the solder shell 31 on the superconducting tape 1 by a brass strip larger than the width of the superconducting tape 1; after multiple low-temperature tests, it was found that the turn-to-turn resistivity of the non-insulated superconducting coil was stable at 3.5μΩ·cm 2 The inter-turn resistivity of the uninsulated superconducting coil is increased by about 4%, and the fluctuation range does not exceed 4%; the increased inter-turn resistivity of the uninsulated superconducting coil also reduces the time constant of the charging and discharging process of the low-temperature test to about 140s, which greatly shortens the time waiting for the voltage to stabilize during the test of the uninsulated superconducting coil; after many tests, the inter-turn resistivity fluctuation range is low, which also greatly enhances the overall Joule thermal stability of the uninsulated superconducting coil; at the same time, the brass parallel winding also enhances the overall mechanical stability of the uninsulated superconducting coil and enhances the cooling effect of the uninsulated superconducting coil.

[0057] In the above embodiments of the present application, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, please refer to the relevant description of other embodiments.

[0058] The above are only preferred implementations of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A method for manufacturing a non-insulated superconducting coil, characterized in that: include: The superconducting tape and a metal tape having a width greater than that of the superconducting tape are overlapped and wound together, and a predetermined number of turns are wound to obtain a winding coil; After the wound coil is obtained, the wound coil is welded by using a solder dipping device, so that the solder fills the gap between the metal strip and the superconducting tape and forms a welding layer in the gap between the metal strip and the superconducting tape to obtain a welded coil; After welding is completed, the solder shell located on the annular surface of the welded coil is removed until the metal strip is exposed, thereby obtaining a non-insulated superconducting coil.

2. The method for manufacturing a non-insulated superconducting coil according to claim 1, characterized in that: During the winding process of the metal tape and the superconducting tape, when the metal tape and the superconducting tape intersect, the superconducting tape and the metal tape are arranged in a staggered manner so that they can be arranged in an alternating concave and convex manner on the annular surface of at least one side of the winding coil after intersecting, overlapping and winding.

3. The method for manufacturing a non-insulated superconducting coil according to claim 2, characterized in that: The solder shell on one side of the alternately concave and convex arrangement is polished so that the polished surface exposes the metal strip, and the metal strip separates the solder shells on the superconducting tapes of adjacent turns.

4. The method for manufacturing a non-insulated superconducting coil according to claim 1, characterized in that: The metal tape and the superconducting tape are tinned before being wound together.

5. The method for manufacturing a non-insulated superconducting coil according to claim 1, characterized in that: The solder dipping device comprises a forced convection heating box, a dipping mold arranged in the forced convection heating box, a first solder tank and a second solder tank, and a gas circuit assembly; The impregnation mold includes a housing cavity for winding the coil and a first communication port and a second communication port connected to the housing cavity; the first solder tank has a first gas path port and a first solder filling port, the first gas path port is connected to the gas path component, and the first solder filling port is connected to the first communication port; the second solder tank has a second gas path port and a second solder filling port, the second gas path port is connected to the gas path component, and the second solder filling port is connected to the second communication port; When the wound coil is dipped in solder, the wound coil is placed in the dipping mold, and the forced convection heating box heats the solder into liquid solder; under the gas pressure provided by the gas path component, the liquid solder flows out from one of the first solder tank and the second solder tank, flows through the accommodating cavity of the dipping mold to dip the wound coil, and then flows into the other solder tank of the first solder tank and the second solder tank; the heating is stopped, the liquid solder is cooled into solid solder, the dipping mold is removed, the solder dipping of the wound coil is completed, and the welded coil is obtained.

6. A non-insulated superconducting coil, characterized in that: include: A winding coil having a metal strip and a superconducting tape wound with a preset number of turns, wherein the width of the metal strip is greater than the width of the superconducting tape; The metal tape and the superconducting tape are arranged alternately in convex and concave shapes on the annular surface of at least one side of the winding coil; A welding layer is filled between the metal tape and the superconducting tape.

7. The non-insulated superconducting coil according to claim 6, characterized in that: The metal tape separates adjacent turns of the superconducting tape.

8. The non-insulated superconducting coil according to claim 6 or 7, characterized in that: The width of the metal tape is 1.1 to 1.5 times the width of the superconducting tape.

9. The non-insulated superconducting coil according to claim 6, characterized in that: The metal belt comprises a brass belt or a stainless steel belt.

Images