Connecting structure and connecting method of superconducting tape and connecting superconducting wire

Abstract

The invention belongs to the technical field of superconducting wires, and relates to a connecting structure and a connecting method of superconducting tapes and a connecting superconducting wire. The invention relates to a connecting structure of REBCO superconducting tapes. The connecting structure comprises a first REBCO superconducting tape and a second REBCO superconducting tape, the to-be-connected areas of the first REBCO superconducting tape and the second REBCO superconducting tape are in a step shape, and the splicing angle of the to-be-connected areas is an acute angle. When the REBCO superconducting tape is connected through the connecting structure of the REBCO superconducting tape, the electrical transport performance of the connector is not affected by an intrinsic weak connecting structure of the REBCO layer in the vertical direction, pressure does not need to be applied, and the connecting process is conducted in an open environment.

Description

Technical Field

[0001] The invention belongs to the technical field of superconducting wires, and relates to a connection structure and a connection method of superconducting tapes and a connected superconducting wire. Background Art

[0002] High temperature superconductor REBa 2 Cu 3 O 7-x The second generation of high temperature superconducting tapes represented by REBCO (abbreviated as REBCO, RE is a rare earth element such as Y, Sm, Gd) combines the excellent basic physical properties of REBCO superconductors and the biaxial texture advantages of coated conductors, and thus exhibit excellent superconducting properties (high critical current density and irreversible field) and excellent mechanical strength in the liquid nitrogen temperature zone. The preparation of superconducting devices often requires very long superconducting wires. In particular, in the development of large and medium-sized magnets, the amount of superconducting wires may weigh several tons. However, due to process limitations, the prepared superconducting wires cannot take into account both length and overall performance at the same time. When used, it is necessary to prepare joints to connect relatively short wires to meet the length requirements. The conductivity and mechanical properties at the joints of superconducting wires are greatly reduced compared to those of superconducting wires. Therefore, the performance of superconducting wire joints is also one of the key factors affecting their practical application.

[0003] At present, the main connection methods of the second-generation high-temperature superconducting wires are: brazing, diffusion welding and melt diffusion welding. Brazing mainly uses low-temperature solder to connect the metal protective layer of the superconducting wire, while diffusion welding is a direct connection of the silver layer. Since there is resistance between the solder layer and the metal layer of the superconducting wire itself, the joint prepared by the above connection method will also have a certain resistance. In order to achieve a resistance-free superconducting joint, it is necessary to directly connect the superconducting layers of the two superconducting wires. Connecting the superconducting layer interface by melt diffusion welding is one of the currently feasible methods. Melt diffusion welding is a method for preparing a superconducting joint by melting part of the interface of the two superconducting layers and diffusing them to each other and tightly connecting them into one. This method is very complicated. It mainly removes the metal layer of the superconducting wire and performs laser drilling on the part to be connected, and then applies a certain pressure and high temperature to the connection area for heat treatment to connect the superconducting layer interface into one, and finally restores superconductivity through oxidation annealing. Because the diffusion coefficient of oxygen in the superconducting layer of the second-generation high-temperature superconducting wire is extremely low, the oxidation annealing process lasts for a long time, which greatly affects the preparation efficiency of the superconducting joint, and thus it is difficult to apply it in practice. Laser drilling is a method to introduce oxygen diffusion, but its equipment cost is expensive, the number of holes to be drilled is large, the time is long, and it causes certain damage to the superconducting wire itself, making it difficult to carry out large-scale practical applications. Therefore, a practical method is needed to provide an oxygen diffusion channel for the superconducting layer without affecting the performance of the superconducting joint, thereby greatly reducing the recovery time of the superconducting joint performance.

[0004] The connection methods of the second generation of high temperature superconducting wires are mainly bridging and overlapping. For example, patent CN113593767A discloses a connection method of the second generation of high temperature superconducting wires and a connection superconducting wire, which adopts a combination of bridging and overlapping, and uses a metal base tape, a buffer layer or a thicker silver tape to provide support or isolation for the silver layer and the superconducting layer, thereby ensuring the mechanical properties of the joint. In the current connection method, first, the connection interface is "thickened" relative to the body in the c-axis, and the superconducting current is not only transmitted along the ab axis in the mother tape and the interface area, but also affected by the c-axis connection interface, so that the electrical transport performance at the joint is affected by the intrinsic weak connection structure of YBCO in the c-axis direction; secondly, the heat treatment process of the joint preparation is carried out in a closed environment, and the required thermal and dynamic parameters are difficult to control; finally, pressure is usually required to be applied in the connection area during the preparation of the joint, and the superconducting joint prepared by the prior art is a connection between superconducting layers with ceramic materials as the essence, which is very fragile. Summary of the invention

[0005] The purpose of the present invention is to improve the connection structure of REBCO superconducting tapes, so as to obtain high-performance, short-cycle, and stable-production-process connected superconducting wires. To this end, the present invention provides a connection structure of superconducting tapes and a connection method and a connected superconducting wire to solve this need in the art.

[0006] On the one hand, the present invention relates to a connection structure of REBCO superconducting tapes, comprising: a first REBCO superconducting tape and a second REBCO superconducting tape; the structure of the first REBCO superconducting tape is, from top to bottom, a first stable layer, a first REBCO layer, a first buffer layer, and a second stable layer, and the structure of the second REBCO superconducting tape is, from top to bottom, a third stable layer, a second REBCO layer, a second buffer layer, and a fourth stable layer; the first REBCO superconducting tape and the second REBCO superconducting tape are spliced; the areas to be connected of the first REBCO superconducting tape and the second REBCO superconducting tape are step-shaped, and the splicing angle of the areas to be connected is an acute angle.

[0007] Specifically, the splicing angle of the present invention is a relatively small angle formed by a straight line connecting two splicing points of the first REBCO superconducting tape or the second REBCO superconducting tape and parallel lines at both ends of the REBCO superconducting tape.

[0008] Furthermore, the connection structure of REBCO superconducting tapes provided by the present invention constructs a connection area of ​​two REBCO superconducting tapes, and is used to manufacture a joint between two REBCO superconducting tapes.

[0009] Furthermore, in the connection structure of the REBCO superconducting tape provided by the present invention, the second stabilizing layer and the fourth stabilizing layer are aligned and spliced.

[0010] Furthermore, in the connection structure of the REBCO superconducting tape provided by the present invention, the first buffer layer and the second buffer layer are aligned and spliced.

[0011] Furthermore, in the connection structure of the REBCO superconducting tape provided by the present invention, the aligned splicing structure is selected from one of linear, wavy, serrated or arc-shaped.

[0012] Furthermore, in the connection structure of the REBCO superconducting tape provided by the present invention, the value of the splicing angle is 15° to 75°. Different splicing angles correspond to different connection lengths of the joint area, that is, l=d / sinθ; wherein l is the connection length, d is the tape width and is a fixed value, and θ is the splicing angle. As can be seen from the above, the larger the splicing angle, the smaller the connection length. Different splicing angles are designed in the present invention, on the one hand, to increase the nominal connection area of ​​the joint area, so as to increase the actual connection area of ​​the joint area as much as possible; on the other hand, it is also to facilitate the joint manufacturing process (such as cutting, curing, etc.). However, a larger connection length will introduce a large number of defects (such as residual stress, microcracks, lattice distortion, etc.) into the connection area, thereby affecting the oriented texture growth of the thin film deposited in the connection area, and ultimately affecting the performance of the tape joint area. Therefore, considering the actual preparation process and performance of the comprehensive joint, the value of the splicing angle is 15° to 75°.

[0013] Furthermore, in the connection structure of REBCO superconducting tapes provided by the present invention, the exposed length of the first REBCO layer or the second REBCO layer is independently selected from 10 mm to 50 mm.

[0014] In another aspect, the present invention provides a method for connecting REBCO superconducting tapes, comprising: constructing a connection structure of the REBCO superconducting tapes;

[0015] Depositing a REBCO thin film on the surfaces of the first buffer layer and the second buffer layer;

[0016] The REBCO film is transformed from a non-superconducting phase to a superconducting phase, and then a stabilization layer is deposited.

[0017] Furthermore, in the method for connecting REBCO superconducting tapes provided by the present invention, the thickness of the REBCO film is 1 μm to 3 μm.

[0018] Furthermore, in the method for connecting REBCO superconducting tapes provided by the present invention, O 2 Annealing to transform the REBCO film from a non-superconducting phase to a superconducting phase;

[0019] The O 2 Annealing treatment in circulation O2 The annealing is carried out in a heat-resistant atmosphere at a temperature of 400°C to 600°C and a time of 0.5h to 300h.

[0020] In another aspect, the present invention relates to a connected superconducting wire obtained by the method for connecting REBCO superconducting tapes.

[0021] Compared with the prior art, the technical solution provided by the present invention has at least the following beneficial effects or advantages:

[0022] Since the superconducting performance of the superconducting joint of REBCO superconducting tape is mainly limited by the texture degree at the interface of the connection area, and the anisotropy of the superconducting performance in the connection area, the oriented growth template of the intermediate medium and the growth mode of the medium all have a significant impact on the texture at the connection interface of the joint. In this regard, the present invention constructs a second-generation high-temperature superconducting wire using a splicing connection method. First, the direction of the connection interface is parallel to the c-axis, and the superconducting current is transmitted along the ab axis in both the mother tape and the interface area. The electrical transport performance at the joint is not affected by the intrinsic weak connection structure of the REBCO superconducting interface in the c-axis direction; secondly, the heat treatment process of the joint preparation is carried out in an open environment, and the required thermal and kinetic parameters are easier to optimize and control, especially in the joint oxygen infiltration heat treatment process, O 2 It can diffuse and penetrate along the surface of the superconducting layer, which can effectively improve the oxygen permeation efficiency; finally, no pressure needs to be applied to the connection area for making the joint, and the structure of the interface area is independent of pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 It is a schematic diagram of the overall structure after the first REBCO superconducting tape and the second REBCO superconducting tape are connected.

[0025] Figure 2 Schematic diagram of the splicing angle of the first REBCO superconducting tape from a top view.

[0026] Figure 3 A comparison chart of the Ic values ​​of joints connecting different superconducting wires.

[0027] In the figure: 1. first REBCO superconducting tape; 2. second REBCO superconducting tape; 3. first stabilizing layer; 4. first REBCO layer; 5. first buffer layer; 6. second stabilizing layer; 7. third stabilizing layer; 8. second REBCO layer; 9. second buffer layer; 10. fourth stabilizing layer; 11. splicing angle of the first REBCO superconducting tape. DETAILED DESCRIPTION

[0028] The technical scheme of the present invention is described below in conjunction with the embodiments, but the present invention is not limited to the following embodiments. The experimental methods and detection methods described in each embodiment are conventional methods unless otherwise specified; the reagents and materials described are available on the market unless otherwise specified. The % in the following embodiments are all mass percentages unless otherwise specified. The ratios in the following embodiments are all mass ratios unless otherwise specified.

[0029] Example 1

[0030] This embodiment provides a connection structure and a connection method for superconducting tapes and a connected superconducting wire.

[0031] At present, the structure of conventional REBCO superconducting tape is composed of a stabilizing layer, a REBCO layer, a buffer layer and a stabilizing layer from top to bottom. The stabilizing layer is generally a metal Cu / Ag stabilizing layer, which is composed of a Cu stabilizing layer and an Ag stabilizing layer from the outside to the inside.

[0032] By connecting the first REBCO superconducting tape 1 and the second REBCO superconducting tape 2, a connection structure and a connection method of superconducting tapes and a connected superconducting wire are provided.

[0033] Step 1: Select a region to be connected of the first REBCO superconducting tape 1, and remove the first stabilizing layer 3 in the region to be connected to expose the first REBCO layer 4.

[0034] Step 2: removing the first REBCO layer 4 to expose the first buffer layer 5.

[0035] Step 3: Select a region of the second REBCO superconducting tape 2 to be connected, and remove the third stabilizing layer 7 in the region to be connected to expose the second REBCO layer 8.

[0036] Step 4: remove the second REBCO layer 8 to expose the second buffer layer 9.

[0037] Step 5: Cut the ends of the first REBCO superconducting tape 1 and the second REBCO superconducting tape 2 in the region to be connected along the length direction to form different acute splicing angles. The schematic diagram of the splicing angle of the first REBCO superconducting tape 1 in a top view is as follows: Figure 2As shown, the first buffer layer 5 and the second stabilizing layer 6 of the first REBCO superconducting tape 1 are spliced, joined and fixed with the second buffer layer 9 and the fourth stabilizing layer 10 of the second REBCO superconducting tape 2. The overall structure after the first REBCO superconducting tape 1 and the second REBCO superconducting tape 2 are connected is as shown in FIG. Figure 1 The above steps result in a connection structure of superconducting tapes.

[0038] Step 6: depositing a REBCO film on the surface of the first buffer layer 5 and the second buffer layer 9 in the area to be connected, so as to connect the first REBCO layer 4 and the second REBCO layer 8.

[0039] Step 7: The strip joints on which the REBCO thin film medium is deposited are O 2 Annealing treatment transforms the REBCO film in the joint area from a non-superconducting phase to a superconducting phase, thereby making the connection area of ​​the strip obtain superconducting properties.

[0040] Step 8: Complete O 2 The annealed connection area is further deposited with Cu and Ag to obtain a metal Cu / Ag stabilization layer. The above steps result in a connected superconducting wire connected by the first REBCO superconducting tape 1 and the second REBCO superconducting tape 2.

[0041] Generally, in step 1 and step 3, FeCl 3 The Cu stabilization layer of REBCO superconducting tape was stripped by etching with a solution (solvent is anhydrous ethanol), and then NH 3 ·H 2 O and H 2 O 2 The mixed solution (NH 3 (H 2 O and H 2 O 2 The mixing ratio is 1:1) to etch and strip the Ag stabilization layer of the REBCO strip.

[0042] Generally, in step 2 and step 4, laser technology is used to peel the REBCO layer from the surface of the buffer layer, leaving an exposed length of 10 mm to 50 mm.

[0043] Preferably, in step 2 and step 4, high-frequency ultraviolet laser technology is used to reduce the influence of the thermal effect of the laser on the strip.

[0044] Exemplarily, the splicing angle in step 5 is any acute angle, such as 15°, 45°, or 75°.

[0045] Preferably, the splicing angle in step 5 is 15° to 75°, 15° to 45°, or 45° to 75°.

[0046] Generally, in step 5, the joints are spliced ​​and fixed using metal slots of suitable specifications to limit and fix the position of the strip connection area, and are made of high-temperature alloy materials.

[0047] Illustratively, in step 5, the shape of the ends of the to-be-connected regions of the first REBCO superconducting tape 1 and the second REBCO superconducting tape 2 cut along the length direction is not particularly limited, but the splicing angle is required to be any acute angle, and the splicing structure is selected from one of linear, wavy, serrated or arc-shaped.

[0048] Generally, in step 6, the REBCO thin film is deposited by in-situ growth.

[0049] Specifically, in step 6, the specific method of in-situ growth is pulsed laser deposition (PLD) technology; RE in the REBCO film is a rare earth element such as Y, Sm, Gd, etc.

[0050] Illustratively, in step 6, the deposited thickness of the REBCO film is 1 μm to 3 μm.

[0051] Typically, in step 7, O 2 Annealing treatment is carried out in the flow O 2 The annealing is carried out in a vacuum atmosphere at a temperature of 400°C to 600°C and a time of 0.5h to 300h.

[0052] Generally, in step 8, the Cu is deposited by vacuum evaporation, and the Ag is deposited by electroplating.

[0053] Example 2

[0054] This example includes the following steps:

[0055] Step 1: First, FeCl 3 The Cu stabilizing layer of the REBCO strip to be connected was corroded and stripped off by a solution prepared by mixing NH 3 (H 2 O and H 2 O 2 The mixed solution corrodes and strips the Ag stabilizing layer of the REBCO strip in the area to be connected, so that the REBCO layer of the strip is completely exposed;

[0056] Step 2: Use high-frequency ultraviolet laser technology to etch and peel off the REBCO layer in the area to be connected of the REBCO strip, so that the buffer layer of the strip is completely exposed, and the exposed length of the REBCO layer is 50 mm;

[0057] Step 3: Use high-frequency ultraviolet laser technology to cut the area to be connected of the REBCO strip with the buffer layer peeled off to a splicing angle of 15°. Place the cut strips on the same plane and splice them together at the cut angle. Then place the spliced ​​strips in a fixed groove made of high-temperature alloy material to ensure that the strips to be connected are always on the same plane and in the same position. Figure 1 Shown is a schematic diagram of the strip splicing structure;

[0058] Step 4: Using pulsed laser deposition (PLD) technology, a 3 μm thick REBCO film is deposited on the surface of the buffer layer in the area to be connected. The film will grow in an oriented manner under the induction of the texture of the buffer layer, and finally a REBCO film with a biaxial texture is obtained.

[0059] Step 5: Place the strip with the REBCO film deposited in the area to be connected in a circulating O 2 In the atmosphere, annealing treatment is carried out at 400°C for 5 hours. After annealing, the crystal structure of the REBCO film changes from a non-superconducting phase to a superconducting phase, so that the strip connection area obtains superconducting properties;

[0060] Step 6: Vacuum evaporation and electroplating techniques are used to complete the O 2 Ag and Cu stabilization layers are deposited on the joint area of ​​the annealed REBCO strip to enhance the mechanical strength of the joint area.

[0061] Example 3

[0062] This example includes the following steps:

[0063] Step 1: First, FeCl 3 The Cu stabilizing layer of the REBCO strip to be connected was corroded and stripped off by a solution prepared by mixing NH 3 (H 2 O and H 2 O 2 The mixed solution corrodes and strips the Ag stabilizing layer of the REBCO strip in the area to be connected, so that the REBCO layer of the strip is completely exposed;

[0064] Step 2: Use high-frequency ultraviolet laser technology to etch and peel off the REBCO layer in the area to be connected of the REBCO strip, so that the buffer layer of the strip is completely exposed, and the exposed length of the REBCO layer is 30 mm;

[0065] Step 3: Use high-frequency ultraviolet laser technology to cut the area to be connected of the REBCO strip with the buffer layer peeled off to a 45° splicing angle. Place the cut strips on the same plane and splice them together at the cut angle. Then place the spliced ​​strips in a fixed groove made of high-temperature alloy material to ensure that the strips to be connected are always on the same plane and in the same position. Figure 1 Shown is a schematic diagram of the strip splicing structure;

[0066] Step 4: Using pulsed laser deposition (PLD) technology, a 2 μm thick REBCO film is deposited on the surface of the buffer layer in the area to be connected. The film will grow in an oriented manner under the induction of the texture of the buffer layer, and finally a REBCO film with a biaxial texture is obtained;

[0067] Step 5: Place the strip with the REBCO film deposited in the area to be connected in a circulating O 2 In the atmosphere, annealing treatment is carried out at 400°C for 5 hours. After annealing, the crystal structure of the REBCO film changes from a non-superconducting phase to a superconducting phase, so that the strip connection area obtains superconducting properties;

[0068] Step 6: Vacuum evaporation and electroplating techniques are used to complete the O 2 Ag and Cu stabilization layers are deposited on the joint area of ​​the annealed REBCO strip to enhance the mechanical strength of the joint area.

[0069] Example 4

[0070] This example includes the following steps:

[0071] Step 1: First, FeCl 3 The Cu stabilizing layer of the REBCO strip to be connected was corroded and stripped off by a solution prepared by mixing NH 3 (H 2 O and H 2 O 2 The mixed solution corrodes and strips the Ag stabilizing layer of the REBCO strip in the area to be connected, so that the REBCO layer of the strip is completely exposed;

[0072] Step 2: Use high-frequency ultraviolet laser technology to etch and peel off the REBCO layer in the area to be connected of the REBCO strip, so that the buffer layer of the strip is completely exposed, and the exposed length of the REBCO layer is 10 mm;

[0073] Step 3: Use high-frequency ultraviolet laser technology to cut the area to be connected of the REBCO strip with the buffer layer peeled off to a splicing angle of 75°. Place the cut strips on the same plane and splice them together at the cut angle. Then place the spliced ​​strips in a fixed groove made of high-temperature alloy material to ensure that the strips to be connected are always on the same plane and in the same position. Figure 1 Shown is a schematic diagram of the strip splicing structure;

[0074] Step 4: Using pulsed laser deposition (PLD) technology, a 1 μm thick REBCO film is deposited on the surface of the buffer layer in the area to be connected. The film will grow in an oriented manner under the induction of the texture of the buffer layer, and finally a REBCO film with a biaxial texture is obtained.

[0075] Step 5: Place the strip with the REBCO film deposited in the area to be connected in a circulating O 2 In the atmosphere, annealing treatment is carried out at 400°C for 5 hours. After annealing, the crystal structure of the REBCO film changes from a non-superconducting phase to a superconducting phase, so that the strip connection area obtains superconducting properties;

[0076] Step 6: Vacuum evaporation and electroplating techniques are used to complete the O 2 Ag and Cu stabilization layers are deposited on the joint area of ​​the annealed REBCO strip to enhance the mechanical strength of the joint area.

[0077] Comparative Example

[0078] This comparative example is the same as Example 2, except that the splicing angle is 90°.

[0079] The measured Ic values ​​of the joints of Examples 2 to 3 and the comparative example are shown in Tables 1 and Figure 3 shown.

[0080] Table 1: Connector Ic values

[0081] Ic value (77K, self-field) / A Example 2 46 Example 3 42 Example 4 31 Comparative Example 23

[0082] From Table 1 and Figure 3 It can be seen that when the splicing angle is an acute angle, the joint Ic value is higher than when the splicing angle is 90°; as the splicing angle becomes smaller, the joint Ic value becomes higher, indicating that the present invention constructs a second-generation high-temperature superconducting wire using a splicing connection method, which can effectively improve the joint quality.

[0083] As described above, the basic principle, main features and advantages of the present invention are well described. The above embodiments and descriptions are only descriptions of the preferred implementation modes of the present invention, and the present invention is not limited by the above embodiments. Without departing from the spirit and scope of the present invention, various changes and improvements made by ordinary technicians in this field to the technical solution of the present invention should fall within the protection scope determined by the present invention.

Claims

1. A connection structure of a REBCO superconducting tape, comprising: A first REBCO superconducting tape (1) and a second REBCO superconducting tape (2); the structure of the first REBCO superconducting tape is, from top to bottom, a first stabilizing layer (3), a first REBCO layer (4), a first buffer layer (5) and a second stabilizing layer (6); the structure of the second REBCO superconducting tape (2) is, from top to bottom, a third stabilizing layer (7), a second REBCO layer (8), a second buffer layer (9) and a fourth stabilizing layer (10); characterized in that: The first REBCO superconducting tape (1) and the second REBCO superconducting tape (2) are spliced; The regions to be connected of the first REBCO superconducting tape (1) and the second REBCO superconducting tape (2) are step-shaped, and the splicing angle of the regions to be connected is an acute angle.

2. The connection structure of REBCO superconducting tapes according to claim 1, characterized in that: The second stabilizing layer (6) and the fourth stabilizing layer (10) are aligned and spliced.

3. The connection structure of REBCO superconducting tapes according to claim 2, characterized in that: The first buffer layer (5) and the second buffer layer (9) are aligned and spliced.

4. The connection structure of REBCO superconducting tapes according to claim 2, characterized in that: The aligned splicing structure is selected from one of linear, wavy, serrated or arc-shaped.

5. The connection structure of REBCO superconducting tapes according to claim 1, characterized in that: The value of the splicing angle is 15° to 75°.

6. The connection structure of REBCO superconducting tapes according to claim 1, characterized in that: The exposed length of the first REBCO layer (4) or the second REBCO layer (8) is independently selected from 10 mm to 50 mm.

7. A method for connecting REBCO superconducting tapes, characterized in that: include: Constructing a connection structure of REBCO superconducting tapes as claimed in any one of claims 1 to 6; Depositing a REBCO thin film on the surfaces of the first buffer layer (5) and the second buffer layer (9); The REBCO film is transformed from a non-superconducting phase to a superconducting phase, and then a stabilization layer is deposited.

8. The method for connecting REBCO superconducting tapes according to claim 7, characterized in that: The thickness of the REBCO film is 1 μm to 3 μm.

9. The method for connecting REBCO superconducting tapes according to claim 7, characterized in that: Transforming the REBCO film from a non-superconducting phase to a superconducting phase by an O2 annealing treatment; The O2 annealing treatment is carried out in a circulating O2 atmosphere, with an annealing temperature of 400°C to 600°C and a time of 0.5h to 300h.

10. A connected superconducting wire obtained by the method for connecting REBCO superconducting tapes according to any one of claims 7 to 9.

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