High-temperature superconducting current lead structure and preparation method thereof

Abstract

The invention discloses a high-temperature superconducting current lead structure and a preparation method thereof, and relates to the field of high-temperature superconducting material preparation, and the high-temperature superconducting current lead structure comprises a magnetic material tube and a high-temperature superconducting section wrapped in the magnetic material tube; the high-temperature superconducting section comprises a first high-temperature superconducting stack and a second high-temperature superconducting stack, and the first high-temperature superconducting stack and the second high-temperature superconducting stack are arranged in the length direction of the magnetic material tube and are formed by stacking a plurality of high-temperature superconducting strips; the partition plate is used for separating the first high-temperature superconducting stack and the second high-temperature superconducting stack; and one end of the copper plate is simultaneously connected with the same-direction end parts of the first high-temperature superconducting stack and the second high-temperature superconducting stack. By adopting the scheme, an external magnetic field is shielded through the magnetic material tube, and the two high-temperature superconducting strip stacks are separated from the middle through the partition plate, so that the magnetic coupling effect between the two high-temperature superconducting strip stacks is reduced, the critical current of the high-temperature superconducting strip stacks in the self-field is increased, and the test stability and reliability are improved.

Description

Technical Field

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

[0002] High-temperature superconducting materials have good current-carrying performance at temperatures higher than liquid helium and in strong magnetic fields. They have been widely used in fields including superconducting power transmission cables, superconducting energy storage, superconducting current limiters, superconducting magnetic levitation, and strong magnetic field magnets, and are considered to be 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 characteristic of high-temperature superconductors. The measurement of electromagnetic characteristics such as critical current of high-temperature superconducting materials under background fields is of great significance for the design of superconducting devices.

[0003] At present, there are two main types of low-temperature test dewars for critical current testing of high-temperature superconducting materials under background fields: immersion type and conduction cooling type. Among them, the conduction cooling type low-temperature test dewar does not require expensive liquid helium refrigerant, but uses conduction cooling methods such as refrigerators or cold helium to cool the sample to the low-temperature test temperature, thereby greatly reducing the test cost. The high-temperature superconducting current lead is an important component of the low-temperature test dewar. Its function is to transmit large current to the sample under test. 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 effect 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 under test 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, which often leads to serious consequences such as heating of the current lead or even burning. 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, where high-temperature superconducting tapes are stacked and tied together and welded to a skeleton with poor thermal conductivity such as stainless steel, and an epoxy insulation sleeve is used on the outside as insulation. The existing high-temperature superconducting current lead structure has a low critical current under a magnetic field, resulting in poor stability and reliability of the current lead, and the current lead is easily burned when the temperature is high or the magnetic field is large. Summary of the invention

[0005] The present invention aims to solve the deficiencies of the prior art and to provide a high-temperature superconducting current lead structure and a preparation method thereof. By adopting the scheme, an external magnetic field is shielded by a magnetic material tube, and 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 the self-field, and improving the test stability and reliability.

[0006] The present invention is achieved through the following technical solutions: A high-temperature superconducting current lead structure, comprising a magnetic material tube and a high-temperature superconducting section wrapped in the magnetic material tube; The high temperature superconducting section comprises: A first high-temperature superconducting stack and a second high-temperature superconducting stack, wherein the first high-temperature superconducting stack and the second high-temperature superconducting stack are both arranged along the length direction of the magnetic material tube and are both formed by stacking a plurality of high-temperature superconducting tapes; A partition, the partition is located in the magnetic material tube and is used to separate the first high temperature superconducting stack and the second high temperature superconducting stack; Copper plates are provided at both ends of the magnetic material tube, one end of the copper plate is connected to the same-direction ends of the first high-temperature superconducting stack and the second high-temperature superconducting stack, and the other end of the copper plate extends toward the outside of the magnetic material tube.

[0007] Compared with the prior art, the critical current of the high-temperature superconducting current lead structure under the magnetic field is low, resulting in poor stability and reliability of the current lead, and the current lead is easy to burn out when the temperature is high or the magnetic field is large. The present invention provides a high-temperature superconducting current lead structure. According to this scheme, 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, so that the critical current of the high-temperature superconducting stack under the self-field is increased, and the test stability and reliability are improved. In the specific scheme, it includes a magnetic material tube and an internal high-temperature superconducting section. The high-temperature superconducting section is arranged in the magnetic material tube. The magnetic material tube is preferably a soft magnetic material, so as to play a role in shielding the external magnetic field, and by reducing the magnetic field around the high-temperature superconducting stack, the critical current of the high-temperature superconducting stack is increased. The high temperature superconducting section includes a first high temperature superconducting stack and a second high temperature superconducting stack, both of which are formed by stacking a number of high temperature superconducting tapes and are in a square, polygonal or other arbitrary shape; a partition is sandwiched in the middle between the first high temperature superconducting stack and the second high temperature superconducting stack, and the first high temperature superconducting stack and the second high temperature superconducting stack are separated from the middle by the partition, thereby reducing the magnetic coupling effect between the two high temperature superconducting tape stacks, so that the critical current of the high temperature superconducting stack under the self-field is increased, and the stability and reliability of the current lead are improved. Copper plates are connected to the same-direction ends of the first high temperature superconducting stack and the second high temperature superconducting stack, so that the current is divided and merged through the copper plates, and the interface is led out through the protruding part of the copper plates toward the outside of the magnetic material tube.

[0008] Furthermore, in order to reduce the thermal conductivity, the partition is made of stainless steel. In this solution, since the stainless steel plate has a lower thermal conductivity, it can further reduce the heat leakage of the lead wire and reduce the heat leakage of the current lead wire to the test sample. At the same time, it can also provide a shunt channel when the superconducting lead wire quenches. When the superconducting lead wire quenches, the stainless steel plate can provide current shunt and improve the stability of the current lead wire.

[0009] Furthermore, as a specific connection method of the copper plate, one end of the copper plate extends into the magnetic material tube, and the ends of the first high-temperature superconducting stack and the second high-temperature superconducting stack in the same direction partially clamp the one end of the copper plate. In this solution, the thickness of the copper plate is preferably the same as the thickness of the partition, the partition is clamped in the middle of the first high-temperature superconducting stack and the second high-temperature superconducting stack, the first copper plate and the second copper plate are 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 on the end of the partition to form an integral high-temperature superconducting section.

[0010] Furthermore, in order 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, and the rectangular side surface contacts the surface of the copper plate, and the contact length is not less than 5 cm. In this way, through the larger contact surface, it is ensured that the current in the high temperature superconducting stack can be effectively transferred to the copper plate, and the lead joint resistance is reduced, and the heat generation of the joint is reduced.

[0011] Furthermore, the first high-temperature superconducting stack, the second high-temperature superconducting stack, the partition and the copper plate are tied together to fix the lead structure and facilitate lead production. It is configured as follows: the circumferential side of the high-temperature superconducting section is circumferentially tied with a copper binding tape.

[0012] Furthermore, in order to fill the internal gaps, the gaps inside the magnetic material tube are filled with solder. In this solution, the solder filling is performed by vacuum solder pressure impregnation, which not only fills the gaps and improves the mechanical stability, but also reduces the resistance between the superconducting tapes in the high-temperature superconducting stack, which helps to shunt the superconducting tapes.

[0013] Furthermore, in order to improve the insulation performance of the current lead, an epoxy resin tube is also included to cover the magnetic material tube.

[0014] Furthermore, the outer side of the magnetic material tube is connected to the inner side of the epoxy resin tube via low-temperature glue.

[0015] Furthermore, in order to facilitate the connection of the two ends of the high-temperature superconducting current lead, the two copper plates are respectively provided with a first positioning hole and a second positioning hole on the portions extending toward the outside of the magnetic material tube.

[0016] In a further embodiment, the present invention also provides a method for preparing a high-temperature superconducting current lead structure, comprising the following steps: First, high temperature superconducting tapes are arranged in a stacked manner to form a first high temperature superconducting stack and a second high temperature superconducting stack; Then, a partition is arranged in the middle between the first high-temperature superconducting stack and the second high-temperature superconducting stack, copper plates are arranged at both ends to form a high-temperature superconducting section, and copper binding tapes are tied around the circumference of the high-temperature superconducting section; Inserting the bound high-temperature superconducting segments into the magnetic material tube, and filling the internal gaps of the magnetic material tube by vacuum solder pressure impregnation; Finally, apply low-temperature glue on the outside of the magnetic material tube, and put the epoxy resin tube on the outside of the magnetic material tube to fix it.

[0017] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. The present invention provides a high-temperature superconducting current lead structure and a preparation method thereof. According to the present invention, the external magnetic field is shielded by a magnetic material tube, and 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 the self-field, and improving the test stability and reliability.

[0018] 2. The present invention provides a high-temperature superconducting current lead structure and a preparation method thereof. By adopting this solution, the thermal conductivity of the current lead is reduced by the stainless steel plate, the heat leakage of the lead is reduced, and a shunt channel is provided during quenching. In addition, 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, and the heating of the current lead is reduced.

[0019] 3. The present invention provides a high-temperature superconducting current lead structure and a preparation method thereof. According to this scheme, the gap between the high-temperature superconducting stack and the magnetic material tube is filled by a vacuum pressure solder dipping method, which not only effectively fills the gaps between the strips and between the strip stack and the copper plate, reducing the contact resistance and lead heating; on the other hand, the manufacturing process is simple and easy to manufacture. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without creative work. In the drawings: Figure 1 A schematic structural diagram of a high-temperature superconducting current lead structure provided by the present invention; Figure 2 A schematic diagram of the structure of a high temperature superconducting section provided by the present invention; Figure 3 A side view of the high-temperature superconducting current lead structure provided by the present invention; Figure 4A front view of the high-temperature superconducting current lead structure provided by the present invention; Figure 5 A comparison diagram of the critical currents of the high-temperature superconducting current lead structure provided by the present invention and the existing current lead.

[0021] Marks and corresponding parts names in the attached drawings: 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-spacer, 9-second copper plate, 10-first positioning hole, 11-second positioning hole. DETAILED DESCRIPTION

[0022] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0023] Embodiment 1: Embodiment 1 provides a high temperature superconducting current lead structure, such as Figure 1-Figure 4 As shown, it includes a magnetic material tube 2 and a high temperature superconducting section wrapped in the magnetic material tube 2; The high temperature superconducting section comprises: A first high-temperature superconducting stack 3 and a second high-temperature superconducting stack 6, wherein the first high-temperature superconducting stack 3 and the second high-temperature superconducting stack 6 are both 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 8, the partition 8 being located in the magnetic material tube 2 and 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 connected to the same-direction 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 toward the outside of the magnetic material tube 2 .

[0024] Compared with the prior art, the critical current of the high-temperature superconducting current lead structure under the magnetic field is low, resulting in poor stability and reliability of the current lead, and the current lead is easy to burn out when the temperature is high or the magnetic field is large. The present invention provides a high-temperature superconducting current lead structure. According to this scheme, 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, so that the critical current of the high-temperature superconducting stack under the self-field is increased, and the test stability and reliability are improved. In the specific scheme, it includes a magnetic material tube 2 and an internal high-temperature superconducting section. The high-temperature superconducting section is arranged in the magnetic material tube 2. The magnetic material tube 2 is preferably a soft magnetic material, so as to play a role in shielding the external magnetic field, and by reducing the magnetic field around the high-temperature superconducting stack, the critical current of the high-temperature superconducting stack is increased. The high temperature superconducting section includes a first high temperature superconducting stack 3 and a second high temperature superconducting stack 6, which are both formed by stacking a number of high temperature superconducting tapes and are in a square, polygonal or other arbitrary shape; a partition 8 is sandwiched in the middle between the first high temperature superconducting stack 3 and the second high temperature superconducting stack 6, and the first high temperature superconducting stack 3 and the second high temperature superconducting stack 6 are separated from the middle by the partition 8, thereby reducing the magnetic coupling effect between the two high temperature superconducting tape stacks, so that the critical current of the high temperature superconducting stack under the self-field is increased, and the stability and reliability of the current lead are improved. Copper plates are connected to the same-direction ends of the first high temperature superconducting stack 3 and the second high temperature superconducting stack 6, so that the current is divided and merged through the copper plates, and the interface is led out through the protruding part of the copper plates toward the outside of the magnetic material tube 2.

[0025] In this embodiment, in order 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 lower thermal conductivity, it can further reduce the heat leakage of the lead wire and reduce the heat leakage of the current lead wire to the test sample. At the same time, it can also provide a shunt channel when the superconducting lead wire quenches. When the superconducting lead wire quenches, the stainless steel plate can provide current shunt and improve the stability of the current lead wire.

[0026] In this embodiment, as a specific connection mode of the copper plate, one end of the copper plate extends into the magnetic material tube 2, and the ends of the first high-temperature superconducting stack 3 and the second high-temperature superconducting stack 6 in the same direction partially clamp the one end of the copper plate. In this solution, the thickness of the copper plate is preferably the same as the thickness of the partition 8, the partition 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 the two 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 on the end of the partition 8 to form an integral high-temperature superconducting section.

[0027] In this embodiment, in order 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 surface contacts the surface of the copper plate, and the contact length is not less than 5 cm. In this way, through the larger contact surface, it is ensured that the current in the high temperature superconducting stack can be effectively transferred to the copper plate, and the lead joint resistance is reduced, and the heat generation of the joint is reduced.

[0028] In this embodiment, the first high-temperature superconducting stack 3, the second high-temperature superconducting stack 6, the partition 8 and the copper plate are tied together to fix the lead structure and facilitate lead production. It is configured as follows: the circumferential side of the high-temperature superconducting section is circumferentially tied with a copper binding belt 4.

[0029] In this embodiment, in order to fill the internal gap, the gap inside the magnetic material tube 2 is filled with solder 7. In this solution, the solder 7 is filled by vacuum solder 7 pressure impregnation, which not only fills the gap and improves the mechanical stability, but also reduces the resistance between the superconducting tapes in the high-temperature superconducting stack, which is conducive to the shunting between the superconducting tapes.

[0030] In this embodiment, in order to improve the insulation performance of the current lead, an epoxy resin tube 1 is also included to cover the magnetic material tube 2.

[0031] In this embodiment, the outer side of the magnetic material tube 2 is connected to the inner side of the epoxy resin tube 1 through low-temperature glue.

[0032] In this embodiment, in order to facilitate the connection of the two ends of the high-temperature superconducting current lead, the two copper plates are respectively provided with a first positioning hole 10 and a second positioning hole 11 on the portions extending toward the outside of the magnetic material tube 2 .

[0033] Embodiment 2: Embodiment 2 is further optimized on the basis of Embodiment 1, and further provides a method for preparing a high-temperature superconducting current lead structure, comprising the following specific steps: First, the high temperature superconducting tapes are arranged in a stacked manner to form a first high temperature superconducting stack 3 and a second high temperature superconducting stack 6. A stainless steel plate, a first copper plate 5 and a second copper plate 9 are added between the high temperature superconducting stack and the second high temperature superconducting stack 6, and the copper binding tape 4 is used to wrap and bind the high temperature superconducting stack, the stainless steel plate and the copper plate together.

[0034] Secondly, the high-temperature superconducting stack after binding is inserted into the magnetic material tube 2, and the gap between the copper binding tape 4 and the magnetic material tube 2 is filled by the vacuum solder 7 pressure impregnation method. The process of vacuum solder 7 pressure impregnation is to set a liquid inlet and a liquid outlet at both ends of the current lead. A sealed and heatable storage tank is set at the inlet to heat the low-melting point solder 7 to 200°C, which will not damage the high-temperature superconducting tape and maintain good fluidity. A vacuum pump is set at the outlet. The gap in the current lead is evacuated into a vacuum state by the vacuum pump, and the vacuum degree is about 0.1Pa. At this time, the liquid inlet is opened to fill the gap between the magnetic material tube 2 and the copper binding tape 4, and the gap between the stacked strips with solder 7, thereby reducing the contact resistance between the strips and reducing the heating of the current lead.

[0035] Finally, low temperature glue is applied to the outside of the magnetic material tube 2, and the epoxy resin tube 1 is sleeved and fixed on the outside of the magnetic material tube 2. The epoxy resin tube 1 can improve the insulation performance of the current lead.

[0036] This scheme can significantly increase the critical current of high-temperature superconducting current leads in a magnetic field. Figure 5 As shown, compared with the existing current leads, the high-temperature superconducting current lead proposed by the present technology has a significantly improved critical current under both the self-field and the magnetic field, making the high-temperature superconducting current lead less likely to quench under a larger transmission current in a magnetic field environment, thereby significantly improving the stability of the high-temperature superconducting current lead in the magnetic field and improving the reliability and stability of the conduction-cooled low-temperature test dewar under the background field.

[0037] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A high temperature superconducting current lead structure, characterized in that: It comprises a magnetic material tube (2) and a high-temperature superconducting section coated inside the magnetic material tube (2); The high temperature superconducting section comprises: A first high-temperature superconducting stack (3) and a second high-temperature superconducting stack (6), wherein the first high-temperature superconducting stack (3) and the second high-temperature superconducting stack (6) are both 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 (8), the partition (8) being located inside the magnetic material tube (2) and being used to separate the first high-temperature superconducting stack (3) from 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 connected to the same-direction 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 toward the outside of the magnetic material tube (2).

2. A 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. A high temperature superconducting current lead structure according to claim 1, characterized in that: One end of the copper plate extends into the magnetic material tube (2), and the ends of the first high-temperature superconducting stack (3) and the second high-temperature superconducting stack (6) in the same direction partially clamp the one end of the copper plate therein.

4. A high temperature superconducting current lead structure according to claim 3, characterized in that: The length by which the first high-temperature superconducting stack (3) and the second high-temperature superconducting stack (6) clamp one end of the copper plate is not less than 5 cm.

5. A high temperature superconducting current lead structure according to claim 1, characterized in that: The high-temperature superconducting section is circumferentially bound with a copper binding belt (4).

6. A high temperature superconducting current lead structure according to claim 1, characterized in that: The gap inside the magnetic material tube (2) is filled with solder (7).

7. A high temperature superconducting current lead structure according to claim 1, characterized in that: It also includes an epoxy resin tube (1) that wraps the magnetic material tube (2).

8. A high temperature superconducting current lead structure according to claim 7, characterized in that: The outer side of the magnetic material tube (2) is connected to the inner side of the epoxy resin tube (1) via low-temperature glue.

9. The high temperature superconducting current lead structure according to claim 1, characterized in that: The portions of the two copper plates extending toward the outside of the magnetic material tube (2) are respectively provided with a first positioning hole (10) and a second positioning hole (11).

10. The method for preparing a high-temperature superconducting current lead structure according to any one of claims 1 to 9, characterized in that: The following steps are involved: First, high temperature superconducting tapes are arranged in a stacked manner to form a first high temperature superconducting stack (3) and a second high temperature superconducting stack (6); Subsequently, a partition (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 arranged at both ends to form a high-temperature superconducting section, and a copper binding belt (4) is circumferentially tied around the circumference of the high-temperature superconducting section; Inserting the bound high-temperature superconducting segments into the magnetic material tube (2), and filling the internal gaps of the magnetic material tube (2) by vacuum solder pressure impregnation; Finally, low-temperature glue is applied to the outside of the magnetic material tube (2), and the epoxy resin tube (1) is placed on the outside of the magnetic material tube to fix it.

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