Method for manufacturing an uninsulated superconducting coil and uninsulated superconducting coil

Abstract

This application relates to the field of nuclear fusion technology, providing a method for fabricating a non-insulated superconducting coil and the non-insulated superconducting coil itself. The method includes: stacking and winding a metal strip and a superconducting strip to form a coil with a predetermined number of turns, obtaining a wound coil, wherein the width of the metal strip is greater than the width of the superconducting strip; placing the wound coil in a solder immersion apparatus for solder immersion, obtaining a welded coil; and removing the solder shell from the annular surface of the welded coil to expose the metal strip. By overlapping and winding the superconducting strip and a metal strip with a width greater than the superconducting strip, and then soldering them, the mechanical stability of the non-insulated superconducting coil is improved, while the cooling effect is enhanced. Afterwards, by removing the solder shell to expose the metal strip, the superconducting strip is not damaged during the removal of the solder shell, ensuring the performance of the non-insulated superconducting coil. The metal strip can completely separate adjacent turns of the superconducting strip, further improving the inter-turn resistivity.

Description

Technical Field

[0001] This application relates to the field of nuclear fusion technology, specifically to a method for fabricating a non-insulated superconducting coil and the non-insulated superconducting coil itself. Background Technology

[0002] Uninsulated superconducting coils are coils wound with superconducting tape and without an organic insulating layer between turns. Compared to traditional insulated coils, uninsulated superconducting coils have a more compact structure, stronger mechanical and cooling performance, and can provide higher magnetic field strength, making them suitable for a wider range of applications. Therefore, the mechanical properties, cooling performance, and inter-turn resistivity of uninsulated superconducting coils often have a significant impact on their performance.

[0003] Existing non-insulated superconducting coils often have low inter-turn resistivity, which leads to a large time constant during the charging and discharging process. Furthermore, some non-insulated coils exhibit poor mechanical and cooling performance. Therefore, how to provide sufficient mechanical stability while maximizing the inter-turn resistance and cooling performance to improve the overall performance of non-insulated superconducting coils has become an urgent technical problem to be solved. Summary of the Invention

[0004] In view of this, this application provides a method for fabricating a non-insulated superconducting coil and a non-insulated superconducting coil, to solve the technical problem of how to maximize the inter-turn resistance of the coil and increase the cooling performance to improve the overall performance of the non-insulated superconducting coil while providing sufficient mechanical stability.

[0005] According to a first aspect, embodiments of this application provide a method for fabricating a non-insulated superconducting coil, comprising: overlapping a superconducting strip and a metal strip with a width greater than that of the superconducting strip together and winding them together to obtain a wound coil by winding a predetermined number of turns; after obtaining the wound coil, using a solder immersion device to weld the wound coil so that the solder fills the gap between the metal strip and the superconducting strip and forms a welding layer in the gap between the metal strip and the superconducting strip to obtain a welded coil; after welding is completed, removing the solder shell located on the annular surface of the welded coil to expose the metal strip to obtain a non-insulated superconducting coil.

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

[0007] In one embodiment, the solder shell on one side of the alternating concave and convex arrangement is polished to expose the metal strip, the metal strip separating the solder shell on the superconducting strip of adjacent turns.

[0008] In one embodiment, the metal strip and the superconducting strip are tin-plated before being wound together.

[0009] In one embodiment, the solder impregnation apparatus includes a forced convection heating chamber, an impregnation mold disposed in the forced convection heating chamber, a first solder pot and a second solder pot, and a gas path assembly; wherein, the impregnation mold includes a receiving cavity for winding a coil and a first communication port and a second communication port communicating with the receiving cavity; the first solder pot has a first gas path port and a first solder filling port, the first gas path port communicating with the gas path assembly, and the first solder filling port communicating with the first communication port; the second solder pot has a second gas path port and a second solder filling port, the second gas path port communicating with the gas path assembly, and the second solder filling port communicating with the first communication port. The filling port is connected to the second connecting port; when the wound coil is soldered, the wound coil is placed in the immersion mold, and the forced convection heating box heats the solder into liquid solder; under the gas pressure provided by the gas circuit assembly, the liquid solder flows out from one of the first solder pots and the second solder pots, flows through the receiving cavity of the immersion mold to immerse the wound coil, and then flows into the other solder pot of the first solder pot and the second solder pot; heating is stopped, the liquid solder is cooled into solid solder, the immersion mold is removed, the soldering of the wound coil is completed, and the soldering coil is obtained.

[0010] According to a second aspect, embodiments of this application provide a non-insulated superconducting coil, comprising: a wound coil having a metal strip and a superconducting strip wound with a predetermined number of turns, wherein the width of the metal strip is greater than the width of the superconducting strip; the metal strip and the superconducting strip are arranged in an alternating convex-concave pattern on an annular surface on at least one side of the wound coil; and a welding layer filling the space between the metal strip and the superconducting strip.

[0011] In one embodiment, the metal strip isolates the superconducting strip from adjacent turns.

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

[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 this application, a superconducting tape and a metal tape with a width greater than the superconducting tape are overlapped and wound together. The wound coil is then soldered using a solder immersion process, forming a solder layer in the gap between the metal tape and the superconducting tape to enhance the inter-turn bonding capability and mechanical stability of the non-insulated superconducting coil. Simultaneously, the inter-turn soldering of the metal tape increases the heat capacity of the non-insulated superconducting coil, increases the cooling channels, and thus enhances the cooling effect. Afterwards, the solder shell on the annular surface of the soldered 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 is not damaged during solder shell removal, ensuring the performance of the non-insulated superconducting coil. Furthermore, after removing the solder shell, the metal tape completely separates the solder shells on adjacent turns of the superconducting tape, preventing the reduction in inter-turn resistivity caused by indirect contact between adjacent turns of the superconducting tape through solder. This results in a non-insulated superconducting coil with strong mechanical properties, good cooling effect, and high inter-turn resistivity. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 This is a schematic flowchart of a method for fabricating a non-insulated superconducting coil according to an embodiment of this application;

[0018] Figure 2 A schematic diagram of the structure of a winding machine for a non-insulated superconducting coil provided in an embodiment of this application;

[0019] Figure 3 A schematic diagram of a cross-sectional structure of a non-insulated superconducting coil provided in an embodiment of this application;

[0020] Figure 4 Another cross-sectional structural diagram of a non-insulated superconducting coil provided in the embodiments of this application;

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

[0022] Figure 6 A schematic diagram of the solder dipping apparatus provided in the embodiments of this application;

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

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

[0025] Figure 9 yes Figure 4 , Figure 7 and Figure 8 The diagram shows the inter-turn resistivity test results of three types of non-insulated superconducting coils. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0027] This application provides a method for fabricating a non-insulated superconducting coil, such as... Figures 1 to 6 As shown, the steps include S101 to S103 as follows:

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

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

[0030] In this embodiment, Figure 2 The winding machine shown performs winding. It includes two pay-off reels 6, one carrying a metal strip 2 and the other carrying a superconducting tape 1. The metal strip 2 and the superconducting tape 1 converge and overlap after passing through multiple guide rollers 8, and are wound onto a take-up reel 7. After reaching a predetermined number of turns, a wound coil is obtained. It should be noted that... Figure 2 The winding machine shown is merely an example; similar or other types of winding machines can also be used, as long as they can achieve the technical solution of this application.

[0031] S102. After obtaining the wound coil, a soldering device is used to weld the wound coil, so that the solder fills the gap between the metal strip and the superconducting strip, and a welding layer is formed in the gap between the metal strip and the superconducting strip, thus obtaining a welded coil. Welding the metal strip 2 and the superconducting strip 1 together enhances the inter-turn bonding capability of the non-insulated superconducting coil and enhances the mechanical stability of the non-insulated superconducting coil. At the same time, by welding the metal strip 2 in parallel between the turns, the heat capacity of the non-insulated superconducting coil can be increased, the cooling channels can be increased, and the cooling effect can be enhanced.

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

[0033] In this application, a superconducting tape 1 and a metal tape 2 with a width greater than the superconducting tape 1 are overlapped and wound together. The wound coil is then soldered using a solder immersion process, forming a solder layer 3 in the gap between the metal tape 2 and the superconducting tape 1 to enhance the inter-turn bonding capability and mechanical stability of the uninsulated superconducting coil. Simultaneously, by soldering the metal tape 2 between the turns, the heat capacity of the uninsulated superconducting coil can be increased, increasing the cooling channels and thus enhancing the cooling effect. Finally, the solder layer is applied to the annular surface of the soldered coil. The shell 31 is removed to expose the metal strip 2. Since the width of the metal strip 2 is greater than the width of the superconducting strip 1, the superconducting strip 1 will not be damaged when the solder shell 31 is removed, thus ensuring the performance of the non-insulated superconducting coil. After the solder shell 31 is removed, the metal strip 2 can completely separate the solder shell 31 on the superconducting strip 1 of adjacent turns, preventing the problem of reduced inter-turn resistivity caused by indirect contact between the superconducting strips 1 of adjacent turns through solder. This results in 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 weld layer 3 between the metal strip 2 and the superconducting strip 1 significantly affects the coil's cooling performance. Therefore, to reduce the void ratio of the weld layer 3 and enhance the coil's cooling performance, in this embodiment, the metal strip 2 and the superconducting strip 1 are tin-plated to enhance the solder wetting effect and reduce the void ratio. Furthermore, to reduce the void ratio caused by oxidation during the soldering process, flux is applied before soldering the wound coil. A vacuum pump is used to evacuate the immersion mold before soldering.

[0035] During the winding process of the metal strip 2 and the superconducting strip 1, the metal strip 2 and the superconducting strip 1 are arranged in an alternating concave-convex pattern on at least one side of the annular surface on both sides of the winding coil.

[0036] In one embodiment, during the winding process of the metal strip 2 and the superconducting strip 1, the metal strip 2 and the superconducting strip 1 are arranged flush on one side of the annular surface where the winding coil is formed, and are arranged in an alternating concave-convex pattern on the other side of the annular surface. See also Figure 3 The structure of the uninsulated superconducting coil is shown.

[0037] During the winding process, an alignment base can be set on the take-up reel 7. During the parallel winding process, the superconducting strip 1 and the metal strip 2 are aligned on the alignment base on the annular surface facing the alignment base, while the superconducting strip 1 and the metal strip 2 are arranged in an alternating concave-convex pattern on the other annular surface. After the parallel winding is completed, the side of the winding coil where the metal strip 2 and the superconducting strip 1 are aligned flat is subjected to solder rejection treatment. For example, high-temperature resistant tape can be applied to the side of the metal strip 2 and the superconducting strip 1 that are aligned flat. Then, solder impregnation is performed. After solder impregnation, a solder shell 31 is formed only on the side of the winding coil where the concave-convex pattern is arranged flat. After removing the solder shell 31, an uninsulated superconducting coil is obtained.

[0038] In another embodiment, two coils can be wound together. For example, a coil frame 4 can be mounted on the take-up reel 7, and a guide plate 5 perpendicular to the axis of the coil frame 4 is mounted in the middle of the coil frame 4. The two coils are wound together on both sides of the guide plate 5. During the winding process, the guide plate 5 acts as an alignment base, aligning the metal strip 2 and the superconducting strip 1 on the guide plate 5 for winding. Thus, on the side facing the guide plate 5, the metal strip 2 and the superconducting strip 1 are arranged flush, while on the side away from the guide plate 5, they are arranged in an alternating concave-convex pattern. During solder impregnation, the coil frame 4 and the guide plate 5 can be impregnated together, or the guide plate 5 can be impregnated together. The guide plate 5 and the coil frame 4 can be made of ceramic material, which solder cannot wet. After impregnation, a welded coil with a solder shell 31 formed only on the side of the coil with the alternating concave-convex pattern is obtained. Removing the solder shell 31 yields an uninsulated coil. See also... Figure 4The structure of the uninsulated superconducting coil is shown.

[0039] To enhance the isolation effect of metal strip 2 on superconducting strip 1 and further improve the inter-turn resistivity of the uninsulated superconducting coil, see [reference needed]. Figure 5 The structure of the uninsulated superconducting coil shown has metal strip 2 and superconducting strip 1 arranged in alternating concave and convex patterns on both sides of the annular surface formed by the winding coil.

[0040] To achieve an alternating concave-convex arrangement of the metal strip 2 and the superconducting strip 1 on both sides of the annular surface formed by the winding coil, the metal strip 2 and the superconducting strip 1 can be tin-plated first, and then... Figure 2 When the winding machine shown is winding, the positions of the guide wheels 8 of the metal strip 2 and the superconducting strip 1 are adjusted respectively. When the metal strip 2 and the superconducting strip 1 meet, the superconducting strip 1 is located in the middle of the metal strip 2 so that after meeting, overlapping and winding, the coil can be arranged in an alternating concave and convex pattern on both sides.

[0041] Furthermore, during the winding process, in utilizing Figure 2 When the winding machine shown is used for winding, a heating device can be set at the intersection of the metal strip 2 and the superconducting strip 1 to heat and melt the solder on the metal strip 2 and the superconducting strip 1, and then cool it to pre-fix the superconducting strip 1 and the metal strip 2 before winding. After winding, the coil is fixed and then solder is impregnated. In this way, the metal strip 2 and the superconducting strip 1 are arranged in an alternating concave and convex pattern on the annular surface of the coil. Since the superconducting strip 1 and the metal strip 2 on both sides of the coil are arranged in an alternating concave and convex pattern, when removing the solder shell 31, for example by grinding, the metal strip 2 is closer to the outside. Therefore, grinding the solder shell 31 will not damage the superconducting strip 1, and the solder between adjacent turns of the superconducting strip 1 can be completely removed. This makes the isolation effect of the metal strip 2 on the superconducting strip 1 more thorough, the inter-turn resistivity higher, and more stable.

[0042] When performing solder impregnation, use methods such as Figure 6The solder immersion apparatus shown performs solder immersion. The apparatus includes a forced convection heating chamber 100, a solder pot 200 disposed within the forced convection heating chamber 100, and an immersion mold 300. When immersing the wound coil, the wound coil is placed in the immersion mold 300. The forced convection heating chamber 100 heats the solder pot 200 and the immersion mold 300, causing the solder in the solder pot 200 to enter the immersion mold 300 and immerse the wound coil. In this embodiment, heating the immersion mold 300 with the forced convection heating chamber 100 ensures that the immersion mold 300 and the wound coil placed in the immersion mold 300 are heated sufficiently and uniformly, ensuring that the liquid solder flows sufficiently in the immersion mold 300, filling the gaps in the wound coil and reducing the void ratio of the solder layer 3.

[0043] In an optional embodiment, the solder impregnation apparatus may further include a pneumatic assembly 400 providing a positive pressure gas source; the impregnation mold 300 may include a receiving cavity 310 for winding a coil and a first communication port 320 and a second communication port 330 communicating with the receiving cavity 310; the solder pot 200 may include a first solder pot 210 and a second solder pot 220, wherein the first solder pot 210 has a first pneumatic port 211 and a first solder filling port 212, the first pneumatic port 211 communicating with the pneumatic assembly 400, and the first solder filling port 212 communicating with the first communication port 320; the second solder pot 220... The device has a second gas port 221 and a second solder filling port 222. The second gas port 221 is connected to the gas assembly 400, and the second solder filling port 222 is connected to the second communication port 330. The forced convection heating box 100 heats the solder into liquid solder. Under the gas pressure provided by the gas assembly 400, the liquid solder flows out from one of the solder cans 210 and 220, flows through the receiving cavity 310 of the impregnation mold 300 to impregnate the wound coil, and then flows into the other solder can 210 and 220.

[0044] During the coil impregnation process, the gas path assembly 400 can be switched on and off with the first gas path port 211 and the second gas path port 221 in a time-sharing manner. For example, in one impregnation process, the gas path assembly 400 switches on the connection with the first gas path port 211 and switches off the connection with the second gas path port 221. By applying gas pressure through the gas path assembly 400 and the weight of the liquid solder, the liquid solder in the first solder pot 210 flows into the impregnation mold 300 from the first solder filling port 212 and the first connecting port 320, filling the winding coil and the coil gap. After the impregnation mold 300 is full, it flows out from the second connecting port 330 and flows into the second solder pot 220 through the second solder filling port 222, so as to ensure that the solder can fill the entire impregnation mold 300, while preventing solder splashing and overflow. In addition, the solder in the second solder pot 220 can be directly recycled and reused in the next impregnation process. The immersion mold is held under pressure for a period of time to ensure that the liquid solder is fully immersed in the interlayer gap of the winding coil, so that the winding coil can be fully immersed in the solder, further reducing the porosity of the solder layer 3.

[0045] After heating is stopped, the liquid solder is cooled into solid solder, the impregnation mold 300 is removed, the solder impregnation of the winding coil is completed, and the welding coil is obtained.

[0046] This application also provides an embodiment of a non-insulated superconducting coil, such as Figure 3 As shown, the non-insulated superconducting coil includes a wound coil with a predetermined number of turns formed by winding a metal strip 2 and a superconducting strip 1 together; a solder layer 3 formed by solder is filled between the metal strip 2 and the superconducting strip 1 of the wound coil; wherein the width of the metal strip 2 is greater than the width of the superconducting strip 1, and the metal strip 2 and the superconducting strip 1 are arranged in an alternating convex and concave pattern on at least one annular surface of the wound coil.

[0047] In this embodiment, by winding the metal strip 2 and the superconducting strip 1 together, the inter-turn resistance of the superconducting strip 1 within the uninsulated superconducting coil can be increased, thereby reducing the time constant of the uninsulated superconducting coil during charging and discharging. Simultaneously, solder is used to fill the gaps between the metal strip 2 and the superconducting strip 1, forming a weld layer 3 that welds the metal strip 2 and the superconducting strip 1 together, enhancing the inter-turn bonding capability of the uninsulated superconducting coil and improving its mechanical stability. Furthermore, by winding and welding the metal strip 2 between turns, the heat capacity of the uninsulated superconducting coil can be increased, creating more cooling channels and enhancing the cooling effect. Moreover, the width of the metal strip 2 is greater than the width of the superconducting strip 1, allowing the metal strip 2 to effectively isolate adjacent turns of the superconducting strip 1, preventing direct or indirect contact between them. This results in a lower range of inter-turn resistivity fluctuations and significantly enhances the overall Joule thermal stability of the uninsulated superconducting coil.

[0048] In one embodiment, to reduce the gap between the metal strip 2 and the superconducting strip 1, enhance the overall cooling performance and mechanical strength of the uninsulated superconducting coil, and to stabilize the inter-turn resistivity, a solder layer 3 is formed to fill the gap between the metal strip 2 and the superconducting strip 1, reducing the solder cavity between them. The solder impregnation method allows the solder to form a solder shell 31 on the winding surface of the superconducting strip 1. Since the width of the metal strip 2 is greater than the width of the superconducting strip 1, after soldering, see... Figures 3 to 5 The uninsulated superconducting coil shown has a metal strip 2 separating the solder shell 31 on the superconducting strip 1 of adjacent turns, to prevent the problem of reduced inter-turn resistivity caused by indirect contact between the superconducting strips 1 of adjacent turns through 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 4.0 mm wide strip and a 4.5 mm wide strip as examples, the width of the metal strip 2 can be 5.0 mm. In an optional embodiment, the specific value of the width of the metal strip 2 can 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 has a relatively high resistivity of 7.1 × 10⁻⁶ at 20°C. -8 Ω·m, 4.66 × 10⁻⁶ at 77 K. -8 Ω·m; in contrast, pure copper is copper, so its resistivity is lower than that of brass, at 1.76 × 10⁻⁶ Ω·m. -8 Ω·m, 2.44 × 10⁻⁶ at 77 K. -9 The resistivity of stainless steel at 77 K is 5.4–5.88 × 10⁻⁶ Ω·m. -7 Ω·m.

[0051] The time constant of the superconducting coil during charging and discharging is: τ = L / Rc, where τ is the time constant, L is the coil inductance, and Rc is the inter-turn resistance. It is evident that to reduce the time constant of the coil during charging and discharging, the inter-turn resistance needs to be maximized. Therefore, in this embodiment, the metal strip 2 can be made of brass or stainless steel.

[0052] In another embodiment, since stainless steel has high tensile strength and elastic modulus, using stainless steel strips in parallel winding can provide stable mechanical properties with good resistance to expansion forces for the uninsulated superconducting coil. However, the wettability of metal solder to stainless steel is poor, which can easily form cavities in the weld layer 3, reducing the cooling effect of the uninsulated superconducting coil. Therefore, in this embodiment, stainless steel strips coated or wrapped with brass can be used as metal strip 2 and wound in parallel with the superconducting strip 1. This can provide greater mechanical strength and a larger inter-turn resistivity while minimizing the formation of cavities in the weld layer 3, thereby improving the cooling effect of the coil.

[0053] See Figures 3 to 5 The schematic diagram of the uninsulated superconducting coil in this application shown herein and Figure 7 and Figure 8 The inter-turn resistivity of an uninsulated superconducting coil without metal strips wound in parallel is compared, where, Figure 7 A schematic diagram of a solder-impregnated, non-insulated superconducting coil is shown. Figure 8 A schematic diagram of a non-insulated superconducting coil welded by brazing is shown. Inter-turn resistivity measurements yielded... Figure 9 Shown Figure 7 The coil shown is designated as #1. Figure 8 The coil shown is designated as #2. Figure 4 The coil shown is a test result of the inter-turn resistivity of three types of non-insulated superconducting coils, namely No. 3. It can be seen that the inter-turn resistivity of the non-insulated superconducting coil in this application is larger and more stable.

[0054] Specifically, such as Figure 7 The diagram shows a non-insulated superconducting coil impregnated with solder. Solder is filled between the superconducting strips 1, and a solder shell 31 is formed on the surface of the winding of the superconducting strips 1. The inter-turn resistivity of the coil is measured to be 0.43 μΩ·cm. 2 With low inter-turn resistivity, the time constant of the uninsulated superconducting coil reaches 2090s during the charging and discharging process.

[0055] like Figure 8 The diagram shown illustrates a non-insulated superconducting coil constructed using brazing. This brazed coil connects adjacent layers of superconducting tape 1 by direct heating without external solder. Testing revealed that the inter-turn resistivity of the non-insulated superconducting coil can reach 1.39 μΩ·cm. 2Compared to solder-impregnated coils, brazed non-insulated superconducting coils exhibit significantly increased inter-turn resistance, and the time constant during charge-discharge processes decreases to 658 s. However, after multiple tests, the inter-turn resistance of the brazed non-insulated superconducting coil remains unstable, and its Joule heating is also unstable during charge-discharge. Research revealed that during brazing, the absence of additional solder leads to irregular solder points at the ends of the non-insulated superconducting coil, caused by melting solder, resulting in unstable inter-turn resistance. Furthermore, the lack of additional solder creates cavities in the weld layer 3 between the superconducting strips 1, further increasing the inter-turn resistivity of the brazed non-insulated superconducting coil. These cavities in the weld layer 3 also severely affect the overall cooling performance of the non-insulated superconducting coil, causing Joule heating instability during charge-discharge.

[0056] like Figures 3 to 5 As shown, the non-insulated superconducting coil, which is welded and wound using the metal strip 2 of this application, has its solder shell 31 separated from the superconducting strip 1 by a brass strip larger than the width of the superconducting strip 1. After multiple low-temperature tests, it was found that the inter-turn resistivity of the non-insulated superconducting coil stabilized at 3.5 μΩ·cm. 2 The increased inter-turn resistivity of the non-insulated superconducting coil was maintained within a range of no more than 4%. This increased inter-turn resistivity also reduced the time constant during the charge-discharge process in low-temperature testing to approximately 140 seconds, significantly shortening the time required for voltage stabilization during testing. Multiple tests showed that the low inter-turn resistivity fluctuation also greatly enhanced the overall Joule thermal stability of the non-insulated superconducting coil. Simultaneously, the brass winding also improved the overall mechanical stability of the non-insulated superconducting coil and enhanced its cooling performance.

[0057] In the above embodiments of this application, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0058] The above are merely preferred embodiments of this application. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A method of manufacturing an uninsulated superconducting coil, characterized by, include: A winding coil is obtained by overlapping a superconducting tape and a metal tape with a width greater than that of the superconducting tape and winding them together to form a predetermined number of turns. After obtaining the wound coil, the wound coil is soldered using a solder immersion device, so that the solder fills the gap between the metal strip and the superconducting strip, and a solder layer is formed in the gap between the metal strip and the superconducting strip to obtain a soldered coil. After welding is completed, the solder shell on the annular surface of the welding coil is removed to expose the metal strip, resulting in a non-insulated superconducting coil.

2. The method of making an uninsulated superconducting coil of claim 1, wherein, During the winding process of the metal strip and the superconducting strip, when the metal strip and the superconducting strip intersect, the superconducting strip and the metal strip are staggered so that after intersecting, overlapping and winding, they can be arranged in an alternating concave and convex pattern on at least one side of the annular surface of the wound coil.

3. The method of making an uninsulated superconducting coil of claim 2, wherein, The solder shell on one side of the alternating concave and convex arrangement is polished to expose the metal strip, and the metal strip separates the solder shell on the superconducting strip of adjacent turns.

4. The method for fabricating an uninsulated superconducting coil as described in claim 1, characterized in that, Before winding the metal strip and the superconducting strip together, the metal strip and the superconducting strip are tin-plated.

5. The method for fabricating a non-insulated superconducting coil as described in claim 1, characterized in that, The solder immersion apparatus includes a forced convection heating chamber, an immersion mold disposed in the forced convection heating chamber, a first solder pot and a second solder pot, and a gas circuit assembly; The impregnation mold includes a receiving cavity for winding a coil and a first connecting port and a second connecting port communicating with the receiving cavity. The first solder can has a first gas passage port and a first solder filling port. The first gas passage port is communicating with the gas passage assembly, and the first solder filling port is communicating with the first connecting port. The second solder can has a second gas passage port and a second solder filling port. The second gas passage port is communicating with the gas passage assembly, and the second solder filling port is communicating with the second connecting port. When soldering the wound coil, the wound coil is placed in the immersion mold, and the forced convection heating box heats the solder into liquid solder. Under the gas pressure provided by the gas circuit assembly, the liquid solder flows out from one of the first solder pots and the second solder pot, flows through the receiving cavity of the immersion mold to immerse the wound coil, and then flows into the other of the first solder pots and the second solder pots. Heating is stopped, the liquid solder is cooled into solid solder, the immersion mold is removed, the soldering of the wound coil is completed, and the soldered coil is obtained.

6. A non-insulated superconducting coil, characterized in that, include: A wound coil has a metal strip and a superconducting strip wound with a predetermined number of turns, wherein the width of the metal strip is greater than the width of the superconducting strip; The metal strip and the superconducting strip are arranged in an alternating convex and concave pattern on at least one annular surface of the wound coil; A welding layer is filled between the metal strip and the superconducting strip.

7. The non-insulated superconducting coil as described in claim 6, characterized in that, The metal strip isolates the superconducting tape from adjacent turns.

8. The uninsulated superconducting coil as described in claim 6 or 7, characterized in that, The width of the metal strip is 1.1 to 1.5 times the width of the superconducting strip.

9. The non-insulated superconducting coil as described in claim 6, characterized in that, The metal strip includes brass strip or stainless steel strip.

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