A high-temperature superconducting current lead structure and a preparation method thereof

Abstract

The present invention discloses a high-temperature superconducting current lead structure and a preparation method thereof, which relates to the field of high-temperature superconducting material preparation. The structure includes a magnetic material tube and a high-temperature superconducting section coated inside the magnetic material tube. The high-temperature superconducting section includes: a first high-temperature superconducting stack and a second high-temperature superconducting stack. Both the first high-temperature superconducting stack and the second high-temperature superconducting stack are arranged along the length direction of the magnetic material tube and are each formed by stacking a plurality of high-temperature superconducting tapes; a partition plate for separating the first high-temperature superconducting stack and the second high-temperature superconducting stack; a copper plate, one end of which is connected to the same-direction end parts of both the first high-temperature superconducting stack and the second high-temperature superconducting stack at the same time. By adopting this solution, the external magnetic field is shielded by the magnetic material tube, and the two high-temperature superconducting stacks are separated from the middle by the partition plate, thereby reducing the magnetic coupling effect between the two high-temperature superconducting tape stacks, increasing the critical current of the high-temperature superconducting stack under its own magnetic field, and improving the test stability and reliability.

Description

Technical Field

[0001] The present invention relates to the field of high-temperature superconducting material preparation, and particularly to a high-temperature superconducting current lead structure and a preparation method thereof. Background Art

[0002] High-temperature superconducting materials can have good current-carrying performance at temperatures above liquid helium temperature and in strong magnetic fields. Currently, they have been widely used in fields including superconducting power transmission cables, superconducting energy storage, superconducting fault current limiters, superconducting magnetic levitation, and high-field magnets, and are considered one of the important technical reserves for future superconducting magnets. The critical current of high-temperature superconductors decreases with the increase of magnetic field and temperature. This characteristic is an intrinsic property of high-temperature superconductors. Measuring the electromagnetic properties such as the critical current of high-temperature superconducting materials in a background field is of great significance for the design of superconducting devices.

[0003] Currently, for the cryogenic test dewars used for testing the critical current of high-temperature superconducting materials in a background field, there are mainly two types: immersion type and conduction-cooled type. Among them, the conduction-cooled cryogenic test dewar does not require expensive liquid helium refrigerant, but uses a conduction cooling method such as a refrigerator or cold helium gas to cool the sample to the low-temperature test temperature, thus greatly reducing the test cost. The high-temperature superconducting current lead is an important component of the cryogenic test dewar. Its function is to transmit large current to the sample to be measured, and at the same time, it is necessary to ensure a low thermal conductivity so that the sample temperature will not increase due to the conduction of the current lead. In the actual test environment, the high-temperature superconducting current lead is often in a magnetic field environment. When the temperature of the sample to be measured is high and the magnetic field is high, the critical current of the high-temperature superconducting current lead decreases. When the sample current exceeds the critical current of the current lead, the current lead becomes normal, often resulting in serious consequences such as heating and even burning of the current lead. Therefore, it is of great significance to improve the stability and reliability of the high-temperature superconducting current lead.

[0004] Existing high-temperature superconducting current leads often use a simple stacking method, binding high-temperature superconducting tapes together in a stacked manner and welding them to a skeleton with poor thermal conductivity such as stainless steel, and at the same time using an epoxy insulating sleeve as insulation on the outside. The existing high-temperature superconducting current lead structure has a low critical current in a magnetic field, resulting in poor stability and reliability of the current lead, and the current lead is prone to burning when the temperature is high or the magnetic field is large. Summary of the Invention

[0005] In order to solve the deficiencies of the prior art, the purpose of the present invention is to provide a high-temperature superconducting current lead structure and a preparation method thereof. By adopting this solution, the external magnetic field is shielded by a magnetic material tube, and the two high-temperature superconducting stacks are separated from the middle by a partition, thereby reducing the magnetic coupling effect between the two high-temperature superconducting tape stacks, increasing the critical current of the high-temperature superconducting stack in its self-field, and improving the test stability and reliability.

[0006] The present invention is realized through the following technical solutions:

[0007] A high-temperature superconducting current lead structure, comprising a magnetic material tube and a high-temperature superconducting section coated within the magnetic material tube;

[0008] The high-temperature superconducting section includes:

[0009] A first high-temperature superconducting stack and a second high-temperature superconducting stack, both the first high-temperature superconducting stack and the second high-temperature superconducting stack are arranged along the length direction of the magnetic material tube and are each formed by stacking a plurality of high-temperature superconducting tapes;

[0010] A partition, which is located within the magnetic material tube and is used to separate the first high-temperature superconducting stack and the second high-temperature superconducting stack;

[0011] Copper plates are provided at both ends of the magnetic material tube. One end of each copper plate is simultaneously connected to the co-directional ends of both the first high-temperature superconducting stack and the second high-temperature superconducting stack, and the other end of the copper plate extends towards the outside of the magnetic material tube.

[0012] Compared with the prior art, in the high-temperature superconducting current lead structure, the critical current under a magnetic field is relatively low, resulting in poor stability and reliability of the current lead, and the current lead is prone to burnout when the temperature is relatively high or the magnetic field is relatively large. The present invention provides a high-temperature superconducting current lead structure. By adopting this solution, the two high-temperature superconducting stacks are separated from the middle by a partition, thereby reducing the magnetic coupling effect between the two high-temperature superconducting tape stacks, increasing the critical current of the high-temperature superconducting stack under its own magnetic field, and improving the test stability and reliability. In a specific solution, it includes a magnetic material tube and the internal high-temperature superconducting section. The high-temperature superconducting section is arranged within the magnetic material tube. The magnetic material tube is preferably a soft magnetic material, thereby playing a role in shielding the external magnetic field, reducing the magnetic field around the high-temperature superconducting stack, and increasing the critical current of the high-temperature superconducting stack. The high-temperature superconducting section includes a first high-temperature superconducting stack and a second high-temperature superconducting stack. Both the first high-temperature superconducting stack and the second high-temperature superconducting stack are formed by stacking a plurality of high-temperature superconducting tapes and are in a square, polygonal or any other shape; a partition is clamped in the middle between the first high-temperature superconducting stack and the second high-temperature superconducting stack. By separating the first high-temperature superconducting stack and the second high-temperature superconducting stack from the middle by the partition, the magnetic coupling effect between the two high-temperature superconducting tape stacks is reduced, the critical current of the high-temperature superconducting stack under its own magnetic field is increased, and the stability and reliability of the current lead are improved. Copper plates are connected to the co-directional ends of both the first high-temperature superconducting stack and the second high-temperature superconducting stack, thereby realizing the shunting and converging of the current through the copper plates, and leading out the interface through the protruding part of the copper plate towards the outside of the magnetic material tube.

[0013] Furthermore, to reduce the thermal conductivity, the partition is made of a stainless steel plate. In this solution, since the stainless steel plate has a low thermal conductivity, it can further reduce the heat leakage of the leads, reduce the heat leakage of the current leads to the test sample, and at the same time, it can also provide a shunt channel during a quench. When the superconducting lead experiences a quench, the stainless steel plate can provide current shunting to improve the stability of the current leads.

[0014] Furthermore, as a specific connection method of the copper plate, one end of the copper plate extends into the magnetic material tube, and the co-directional ends of the first high-temperature superconducting stack and the second high-temperature superconducting stack locally clamp one end of the copper plate inside. In this solution, the thickness of the copper plate is preferably the same as that of the partition. The partition is clamped in the middle of the first high-temperature superconducting stack and the second high-temperature superconducting stack, while the first copper plate and the second copper plate are respectively clamped at both ends of the first high-temperature superconducting stack and the second high-temperature superconducting stack, and one end of the copper plate abuts against the end of the partition to form an integral high-temperature superconducting section.

[0015] Furthermore, to reduce the resistance, the length of the first high-temperature superconducting stack and the second high-temperature superconducting stack clamping one end of the copper plate is not less than 5 cm. In this solution, the first high-temperature superconducting stack and the second high-temperature superconducting stack are preferably rectangular. They contact the surface of the copper plate through the rectangular side, and the contact length is not less than 5 cm. In this way, through a large contact surface, it is ensured that the current in the high-temperature superconducting stack can be effectively transmitted to the copper plate, reducing the resistance of the lead joint and minimizing the heat generation at the joint.

[0016] Furthermore, to bind the first high-temperature superconducting stack, the second high-temperature superconducting stack, the partition, and the copper plate together to play a role in fixing the lead structure and facilitating the lead production, it is set that: a copper binding band is circumferentially bound around the periphery of the high-temperature superconducting section.

[0017] Furthermore, to fill the internal voids, the voids inside the magnetic material tube are filled with solder. In this solution, the solder filling is carried out by the method of vacuum solder pressure impregnation. While filling the voids and improving the mechanical stability, it also reduces the resistance between the superconducting tapes in the high-temperature superconducting stack, contributing to the shunting between the superconducting tapes.

[0018] Furthermore, to improve the insulation performance of the current leads, an epoxy resin tube covering the magnetic material tube is also included.

[0019] Furthermore, the outside of the magnetic material tube is connected to the inside of the epoxy resin tube through a low-temperature adhesive.

[0020] Furthermore, to facilitate the connection of both ends of the high-temperature superconducting current leads, the portions of the two copper plates extending towards the outside of the magnetic material tube are respectively provided with a first positioning hole and a second positioning hole.

[0021] In a further aspect, the present invention also provides a method for preparing a high-temperature superconducting current lead structure, comprising the following steps:

[0022] First, arrange the high-temperature superconducting tapes in a stacked manner to form a first high-temperature superconducting stack and a second high-temperature superconducting stack respectively;

[0023] Subsequently, arrange a partition in the middle between the first high-temperature superconducting stack and the second high-temperature superconducting stack, and arrange copper plates at both ends to form a high-temperature superconducting section, and circumferentially bind a copper binding band around the periphery of the high-temperature superconducting section;

[0024] Insert the bound high-temperature superconducting section into a magnetic material tube, and fill the internal void of the magnetic material tube by means of vacuum solder pressure impregnation;

[0025] Finally, apply a low-temperature adhesive on the outside of the magnetic material tube, and sleeve an epoxy resin tube on the outside of the magnetic material tube for fixation.

[0026] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0027] 1. The present invention provides a high-temperature superconducting current lead structure and a method for preparing the same. By adopting this solution, the external magnetic field is shielded by a magnetic material tube, and the two high-temperature superconducting stacks are separated from the middle by a partition, thereby reducing the magnetic coupling effect between the two high-temperature superconducting tape stacks, increasing the critical current of the high-temperature superconducting stack under its own magnetic field, and improving the test stability and reliability.

[0028] 2. The present invention provides a high-temperature superconducting current lead structure and a method for preparing the same. By adopting this solution, the heat conductivity of the current lead is reduced by a stainless steel plate, the heat leakage of the lead is reduced, and at the same time, a shunt channel during quenching is provided. Moreover, there is a sufficient contact length between the copper plate and the high-temperature superconducting tape stack, so that the contact resistance between the high-temperature superconducting stack and the copper plate is small, reducing the heat generation of the current lead.

[0029] 3. The present invention provides a high-temperature superconducting current lead structure and a method for preparing the same. By adopting this solution, the void between the high-temperature superconducting stack and the magnetic material tube is filled by the vacuum pressure solder impregnation method, which not only effectively fills the voids between the tapes, between the tape stacks and the copper plates, reducing the contact resistance and the heat generation of the lead; on the other hand, the manufacturing process is simple and easy to manufacture. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following will briefly introduce the drawings required for the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts. In the drawings:

[0031] Figure 1 Schematic structural diagram of the high-temperature superconducting current lead structure provided by the present invention;

[0032] Figure 2 Schematic structural diagram of the high-temperature superconducting section provided by the present invention;

[0033] Figure 3 Side view of the high-temperature superconducting current lead structure provided by the present invention;

[0034] Figure 4 Front view of the high-temperature superconducting current lead structure provided by the present invention;

[0035] Figure 5 Comparison chart of the critical current between the high-temperature superconducting current lead structure provided by the present invention and the existing current lead.

[0036] Marks in the drawings and corresponding component names:

[0037] 1 - epoxy resin tube, 2 - magnetic material tube, 3 - first high-temperature superconducting stack, 4 - copper binding tape, 5 - first copper plate, 6 - second high-temperature superconducting stack, 7 - solder, 8 - partition board, 9 - second copper plate, 10 - first positioning hole, 11 - second positioning hole. Specific embodiments

[0038] To make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the embodiments and the drawings. The illustrative embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention.

[0039] Embodiment 1: Embodiment 1 provides a high-temperature superconducting current lead structure, as Figures 1 - 4 shown, including a magnetic material tube 2 and a high-temperature superconducting section coated within the magnetic material tube 2;

[0040] The high-temperature superconducting section includes:

[0041] A first high-temperature superconducting stack 3 and a second high-temperature superconducting stack 6, both the first high-temperature superconducting stack 3 and the second high-temperature superconducting stack 6 are arranged along the length direction of the magnetic material tube 2 and are both stacked by a plurality of high-temperature superconducting tapes;

[0042] A partition board 8, the partition board 8 is located within the magnetic material tube 2 and is used to separate the first high-temperature superconducting stack 3 and the second high-temperature superconducting stack 6;

[0043] Copper plates are provided at both ends of the magnetic material tube 2. One end of each copper plate is connected to the co-directional ends of the first high-temperature superconducting stack 3 and the second high-temperature superconducting stack 6 simultaneously, and the other end of the copper plate extends towards the outside of the magnetic material tube 2.

[0044] Compared with the prior art, in which the critical current of the high-temperature superconducting current lead structure under a magnetic field is relatively low, resulting in poor stability and reliability of the current lead, and the current lead is prone to burnout at higher temperatures or stronger magnetic fields, the present invention provides a high-temperature superconducting current lead structure. With this solution, the two high-temperature superconducting stacks are separated from the middle by a partition 8, thereby reducing the magnetic coupling effect between the two high-temperature superconducting tape stacks, increasing the critical current of the high-temperature superconducting stack in its self-field, and improving the test stability and reliability. In a specific embodiment, it includes a magnetic material tube 2 and a high-temperature superconducting section inside. The high-temperature superconducting section is arranged inside the magnetic material tube 2. The magnetic material tube 2 is preferably a soft magnetic material, which can play a role in shielding the external magnetic field, reducing the magnetic field around the high-temperature superconducting stack, and increasing the critical current of the high-temperature superconducting stack. The high-temperature superconducting section includes a first high-temperature superconducting stack 3 and a second high-temperature superconducting stack 6. Both the first high-temperature superconducting stack 3 and the second high-temperature superconducting stack 6 are stacked by a plurality of high-temperature superconducting tapes and are in a square, polygonal or any other shape; a partition 8 is clamped in the middle between the first high-temperature superconducting stack 3 and the second high-temperature superconducting stack 6. By separating the first high-temperature superconducting stack 3 and the second high-temperature superconducting stack 6 from the middle with the partition 8, the magnetic coupling effect between the two high-temperature superconducting tape stacks is reduced, the critical current of the high-temperature superconducting stack in its self-field is increased, and the stability and reliability of the current lead are improved. Copper plates are connected to the co-directional ends of the first high-temperature superconducting stack 3 and the second high-temperature superconducting stack 6, so as to achieve current shunting and confluence through the copper plates, and the interface is led out through the extending part of the copper plate towards the outside of the magnetic material tube 2.

[0045] In this embodiment, to reduce the thermal conductivity, the partition 8 is made of a stainless steel plate. In this solution, since the stainless steel plate has a relatively low thermal conductivity, it can further reduce the heat leakage of the lead, reduce the heat leakage of the current lead to the test sample, and at the same time it can also provide a current shunting channel during a quench. When the superconducting lead quenches, the stainless steel plate can provide current shunting, improving the stability of the current lead.

[0046] In this embodiment, as a specific connection method of the copper plate, one end of the copper plate extends into the magnetic material tube 2, and the same-direction ends of the first high-temperature superconducting stack 3 and the second high-temperature superconducting stack 6 locally clamp one end of the copper plate therein. In this solution, the thickness of the copper plate is preferably the same as that of the partition plate 8. The partition plate 8 is clamped in the middle of the first high-temperature superconducting stack 3 and the second high-temperature superconducting stack 6. The first copper plate 5 and the second copper plate 9 are respectively clamped at both ends of the first high-temperature superconducting stack 3 and the second high-temperature superconducting stack 6, and one end of the copper plate abuts against the end of the partition plate 8 to form an integral high-temperature superconducting section.

[0047] In this embodiment, to reduce the resistance, the length of the first high-temperature superconducting stack 3 and the second high-temperature superconducting stack 6 clamping one end of the copper plate is not less than 5 cm. In this solution, the first high-temperature superconducting stack 3 and the second high-temperature superconducting stack 6 are preferably rectangular, and the rectangular side surfaces contact the surface of the copper plate, and the contact length is not less than 5 cm. In this way, through the large contact surface, it is ensured that the current in the high-temperature superconducting stack can be effectively transmitted to the copper plate, and the resistance of the lead joint is reduced, and the heat generation at the joint is reduced.

[0048] In this embodiment, to bind the first high-temperature superconducting stack 3, the second high-temperature superconducting stack 6, the partition plate 8 and the copper plate together to play a role in fixing the lead structure and facilitating the lead production, it is set that: a copper binding band 4 is circumferentially bound on the periphery of the high-temperature superconducting section.

[0049] In this embodiment, to fill the internal voids, the voids inside the magnetic material tube 2 are filled with solder 7. In this solution, the solder 7 is filled by the method of vacuum solder 7 pressure impregnation. While filling the voids and improving the mechanical stability, the resistance between the superconducting tapes in the high-temperature superconducting stack is also reduced, which helps the shunt between the superconducting tapes.

[0050] In this embodiment, to improve the insulation performance of the current lead, an epoxy resin tube 1 that wraps the magnetic material tube 2 is further included.

[0051] In this embodiment, the outside of the magnetic material tube 2 is connected to the inside of the epoxy resin tube 1 through a low-temperature adhesive.

[0052] In this embodiment, to facilitate the connection of both ends of the high-temperature superconducting current lead, first positioning holes 10 and second positioning holes 11 are respectively provided on the parts of the two copper plates extending towards the outside of the magnetic material tube 2.

[0053] Embodiment 2: Embodiment 2 is further optimized on the basis of Embodiment 1, and a preparation method for a high-temperature superconducting current lead structure is further provided, including the following specific steps:

[0054] First, arrange the high-temperature superconducting tapes in a stacked manner to fabricate a first high-temperature superconducting stack 3 and a second high-temperature superconducting stack 6 respectively. Insert a stainless steel plate, a first copper plate 5, and a second copper plate 9 between the first high-temperature superconducting stack and the second high-temperature superconducting stack 6, and wind and tie them on the outside with a copper binding tape 4, so as to tie the high-temperature superconducting stack, the stainless steel plate, and the copper plate together.

[0055] Secondly, insert the tied high-temperature superconducting stack into a magnetic material tube 2, and use the vacuum solder 7 pressure impregnation method to fill the gap between the copper binding tape 4 and the magnetic material tube 2. The technological process of the vacuum solder 7 pressure impregnation is to set an inlet and an outlet at both ends of the current lead. Set a sealed and heatable storage tank at the inlet, heat the low-melting-point solder 7 to 200°C, which will not damage the high-temperature superconducting tape and has good fluidity. Set a vacuum pump at the outlet. Use the vacuum pump to evacuate the gap in the current lead to a vacuum state, and the vacuum degree is about 0.1 Pa. At this time, open the inlet to make the gap between the magnetic material tube 2 and the copper binding tape 4, and the gap between the tape stacks be filled with solder 7, so as to reduce the contact resistance between the tapes and reduce the heat generation of the current lead.

[0056] Finally, apply low-temperature glue on the outside of the magnetic material tube 2, and sleeved and fixed an epoxy resin tube 1 on the outside of the magnetic material tube 2. The epoxy resin tube 1 can improve the insulation performance of the current lead.

[0057] This solution can significantly improve the critical current of the high-temperature superconducting current lead in a magnetic field. As Figure 5 shown, compared with the existing current leads, the high-temperature superconducting current lead proposed by this technology has a significant increase in the critical current under self-field and magnetic field, making the high-temperature superconducting current lead less likely to quench under a larger transmission current in a magnetic field environment, thus significantly improving the stability of the high-temperature superconducting current lead in a magnetic field and improving the reliability and stability of the conduction-cooled cryogenic test dewar under the background field.

[0058] The specific embodiments described above further elaborate on the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only the specific embodiments of the present invention and is not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A high-temperature superconducting current lead structure, characterized in that It includes a magnetic material tube (2) and a high-temperature superconducting section coated inside the magnetic material tube (2); The high-temperature superconducting section includes: A first high-temperature superconducting stack (3) and a second high-temperature superconducting stack (6). Both the first high-temperature superconducting stack (3) and the second high-temperature superconducting stack (6) are arranged along the length direction of the magnetic material tube (2), and are both formed by stacking a plurality of high-temperature superconducting tapes; A partition plate (8), which is located inside the magnetic material tube (2) and is used to separate the first high-temperature superconducting stack (3) and the second high-temperature superconducting stack (6); Copper plates are provided at both ends of the magnetic material tube (2). One end of the copper plate is simultaneously connected to the co-directional ends of the first high-temperature superconducting stack (3) and the second high-temperature superconducting stack (6), and the other end of the copper plate extends towards the outside of the magnetic material tube (2); One end of the copper plate extends into the magnetic material tube (2), and the co-directional ends of the first high-temperature superconducting stack (3) and the second high-temperature superconducting stack (6) partially clamp one end of the copper plate inside; 2. The high-temperature superconducting current lead structure according to claim 1, characterized in that, The partition plate (8) is made of a stainless steel plate; 3. The high-temperature superconducting current lead structure according to claim 1, characterized in that, The length of the co-directional ends of the first high-temperature superconducting stack (3) and the second high-temperature superconducting stack (6) clamping one end of the copper plate is not less than 5 cm; 4. A high-temperature superconducting current lead structure according to claim 1, characterized in that The circumferential side of the high-temperature superconducting section is circumferentially tied with a copper tie strap (4); 5. A high-temperature superconducting current lead structure according to claim 1, characterized in that The void inside the magnetic material tube (2) is filled with solder (7); 6. The high-temperature superconducting current lead structure according to claim 1, characterized in that It further includes an epoxy resin tube (1) covering the magnetic material tube (2); 7. A high-temperature superconducting current lead structure according to claim 6, characterized in that, The outside of the magnetic material tube (2) is connected to the inside of the epoxy resin tube (1) through a low-temperature adhesive; 8. A high-temperature superconducting current lead structure according to claim 1, characterized in that, First positioning holes (10) and second positioning holes (11) are respectively provided on the parts of the two copper plates extending towards the outside of the magnetic material tube (2); 9. The preparation method of a high-temperature superconducting current lead structure according to any one of claims 1 to 8, characterized in that, It includes the following steps: First, arrange the high-temperature superconducting tapes in a stacked manner to respectively form a first high-temperature superconducting stack (3) and a second high-temperature superconducting stack (6); Subsequently, a partition plate (8) is arranged in the middle between the first high-temperature superconducting stack (3) and the second high-temperature superconducting stack (6), copper plates are respectively arranged at both ends to form a high-temperature superconducting section, and a copper tie strap (4) is circumferentially tied on the circumferential side of the high-temperature superconducting section; Insert the tied high-temperature superconducting section into the magnetic material tube (2), and fill the internal void of the magnetic material tube (2) by means of vacuum solder pressure impregnation; Finally, apply a low-temperature adhesive on the outside of the magnetic material tube (2), and sleeved the epoxy resin tube (1) on the outside of the magnetic material tube for fixation.

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