A method of winding a superconducting magnet

Abstract

This invention discloses a method for winding a superconducting magnet, relating to the field of superconducting magnet technology, comprising the following steps: (1) preparing a REBCO tape without a metal protective layer; (2) preparing a metal tube and heating the metal tube; (3) connecting the silver layer of the REBCO tape to the metal tube; (4) clamping the base tape and buffer layer of the REBCO tape, rotating the metal tube, and winding a first coil on the metal tube; (5) stopping the rotation of the metal tube after the first coil has been wound to a set number of turns, and cutting the REBCO tape; (6) repeating steps (3)-(5) to wind a second coil on the metal tube; (7) plating silver on the circumferential outer surfaces of the first and second coils; (8) performing an oxidation annealing heat treatment on the first and second coils. This invention significantly reduces the volume and outer diameter of the superconducting magnet formed by winding the superconducting magnet, resulting in a more compact structure and the ability to generate a higher magnetic field strength.

Description

Technical Field

[0001] This invention relates to the field of superconducting magnet technology, and in particular to a method for winding a superconducting magnet. Background Technology

[0002] Coated conductors based on rare earth barium copper oxide (REBa2Cu3O7-x, abbreviated as REBCO, where RE represents rare earth elements such as Y and Gd) materials (also known as second-generation high-temperature superconducting tapes or REBCO tapes) have advantages such as high critical transition temperature, strong current carrying capacity, and mechanical properties, and have broad application prospects in fields such as power, energy, strong magnetic fields, and magnetic levitation transportation.

[0003] REBCO tapes are generally composed of a metal alloy substrate (50–100 μm), a buffer layer (~200 nm), a REBCO superconducting layer (1–2 μm), a silver layer (0–2 μm), and a metal protective layer (40–80 μm) in sequence. The buffer layer is used to induce the growth of the REBCO superconducting layer. Currently, REBCO tapes without a metal protective layer are also available on the market.

[0004] Because the baseband and protective layer constitute a very high proportion of the strip thickness (generally greater than 90%), the engineering current density (the ratio of the critical current of the REBCO superconducting layer to the total cross-sectional area of ​​the strip) Je of the strip is not high. When using REBCO strips to wind superconducting magnets, the baseband and protective layer not only contribute no to the magnetic field, but also increase the outer diameter, further reducing the contribution of the outer strip to the magnetic field strength at the magnet's center.

[0005] Furthermore, during the heating, cooling, and excitation processes, the presence of the baseband and protective layer will cause large thermal and electromagnetic stresses inside the magnet, leading to breakage, twisting, and delamination damage of the strip, which will endanger the safe operation of the magnet. Summary of the Invention

[0006] The purpose of this invention is to provide a method for winding a superconducting magnet to solve the problems existing in the prior art, reduce the volume and outer diameter of the superconducting magnet formed by winding, make the structure of the superconducting magnet more compact, and enable it to generate a higher magnetic field strength.

[0007] To achieve the above objectives, the present invention provides the following solution:

[0008] This invention provides a method for winding a superconducting magnet, comprising the following steps:

[0009] (1) Prepare REBCO tape without a metal protective layer;

[0010] (2) Prepare a metal tube that is conductive and resistant to oxidation at high temperatures, and heat the metal tube with a heating device.

[0011] (3) The silver layer at the first end of the REBCO tape is brought into contact with the high-temperature outer surface of the metal tube, so that the silver layer is connected to the outer wall of the metal tube.

[0012] (4) Clamp the base strip and buffer layer at the first end of the REBCO tape, and drive the metal tube to rotate through the driving device. The metal tube drives the silver layer and REBCO superconducting layer of the REBCO tape to rotate, while the REBCO superconducting layer separates from the buffer layer. After the silver layer and the REBCO superconducting layer are wound around the metal tube once, the silver layer of the second turn will be connected to the REBCO superconducting layer of the first layer, that is, the silver layer of the next turn is connected to the REBCO superconducting layer of the previous turn; a first coil is formed on the metal tube.

[0013] (5) When the first coil has been wound to the set number of turns, stop rotating the metal tube and cut the REBCO tape;

[0014] (6) Repeat steps (3)-(5) to wind a second coil on the metal tube, with a gap between the second coil and the first coil, and the winding direction of the second coil is opposite to that of the first coil.

[0015] (7) Silver is plated on the circumferential outer surfaces of the first coil and the second coil; thereby using the outermost REBCO superconducting layer as an electrode;

[0016] (8) Perform oxidation annealing heat treatment on the first coil and the second coil, and use the combination of the metal tube, the first coil and the second coil as a double coil.

[0017] Preferably, the method further includes step (9): repeating steps (1)-(8) to obtain a plurality of the double-coil coils; and connecting the plurality of double-coil coils in sequence to form a superconducting magnet; the first coil or the second coil in the double-coil coil is electrically connected to the first coil or the second coil in the adjacent double-coil coil through a superconducting strip.

[0018] Preferably, the heating device is an electric heating rod, the metal tube is sleeved on the electric heating rod, and there is a gap between the inner wall of the metal tube and the electric heating rod.

[0019] Preferably, the driving device is a geared motor, the metal tube is fixedly connected to the output shaft of the geared motor, and one end of the metal tube is coaxial with the output shaft.

[0020] Preferably, the metal tube is a silver tube.

[0021] Preferably, the heating temperature of the metal tube in step (2) is 400 to 960°C.

[0022] Preferably, steps (2)-(5) are performed in an oxygen atmosphere.

[0023] Preferably, the conveying speed of the REBCO tape in step (4) is 0.001 to 1 m / min; and the outer diameter of the metal tube is greater than 5 mm.

[0024] Preferably, the parameters of the oxidation annealing heat treatment in step (8) include: oxygen partial pressure of 0.1-15 MPa, temperature of 350-600°C, and time of 0.5-300 h.

[0025] The present invention achieves the following technical effects compared to the prior art:

[0026] The superconducting magnet winding method of the present invention removes the baseband, buffer layer and protective layer in the REBCO tape, and forms the magnet coil only with the silver layer and REBCO superconducting layer. This significantly reduces the volume and outer diameter of the superconducting magnet formed by winding the superconducting magnet, and the structure of the superconducting magnet obtained by winding is more compact and can generate a higher magnetic field strength.

[0027] Specifically, since the interlayer bonding force between the REBCO superconducting layer and the buffer layer in the REBCO tape is the weakest, the silver layer can be connected to other materials by taking advantage of the fact that silver softens and becomes sticky at high temperatures. This allows the silver layer and the REBCO superconducting layer to be peeled off from the tape, and a superconducting magnet with high engineering current density can be wound in this way.

[0028] On the other hand, the silver layer and the REBCO superconducting layer are tightly bonded together, exhibiting higher interlayer bonding strength, electrical conductivity, and thermal conductivity, resulting in better quench protection for the magnet. Furthermore, the silver layer has a high oxygen diffusion coefficient, allowing oxygen to more easily penetrate into the magnet coil during oxidation annealing, rapidly restoring the superconducting performance of the REBCO superconducting layer. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the winding of the first coil in the winding method of the superconducting magnet of the present invention;

[0031] Figure 2 This is a schematic diagram of winding the second coil in the method for winding the superconducting magnet of the present invention;

[0032] Figure 3 This is a schematic diagram of the structure of a superconducting magnet obtained by the winding method of the present invention.

[0033] Among them, 1. Silver layer; 2. REBCO superconducting layer; 3. Buffer layer; 4. Baseband; 5. Metal tube; 6. First coil; 7. Double-pancake coil; 8. Superconducting tape. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] The purpose of this invention is to provide a method for winding a superconducting magnet to solve the problems existing in the prior art, reduce the volume and outer diameter of the superconducting magnet formed by winding, make the structure of the superconducting magnet more compact, and enable it to generate a higher magnetic field strength.

[0036] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] like Figures 1-3 As shown, this embodiment provides a method for winding a superconducting magnet, including the following steps:

[0038] (1) Prepare REBCO tape without a metal protective layer;

[0039] (2) Prepare a metal tube 5. The metal tube 5 is conductive and can resist oxidation at high temperature. Heat the metal tube 5 to 400-960°C using a heating device. The reason for using a metal tube 5 that can resist oxidation at high temperature is that if the surface of the metal tube is oxidized, it will separate from the silver layer and generate a large resistance, which is not conducive to current transmission and heat generation, endangering the safety of the magnet.

[0040] In this embodiment, the outer diameter of the metal tube 5 is greater than 5mm, and the metal tube 5 is preferably made of silver. The reason for using silver tube as the metal tube 5 in this embodiment is that silver can easily diffuse and bond together, which is beneficial for peeling; the heating device is an electric heating rod, the metal tube 5 is sleeved on the electric heating rod, and there is a gap between the inner wall of the metal tube 5 and the electric heating rod; in this way, the electric heating rod heats the metal tube 5 through thermal radiation, and the rotation of the metal tube 5 will not interfere with the electric heating rod.

[0041] (3) The silver layer 1 at the first end of the REBCO tape is brought into contact with the high-temperature outer surface of the metal tube 5, so that the silver layer 1 is connected to the outer wall of the metal tube 5.

[0042] (4) The base strip 4 and buffer layer 3 of the first end of the REBCO strip are clamped, and the metal tube 5 is driven to rotate by the driving device. In this embodiment, the driving device is a geared motor. The metal tube 5 is fixedly connected to the output shaft of the geared motor, and one end of the metal tube 5 is coaxial with the output shaft.

[0043] When the metal tube 5 rotates, it drives the silver layer 1 and the REBCO superconducting layer 2 of the REBCO tape to rotate. The tape speed of the REBCO tape is 0.001~1m / min. At the same time, the REBCO superconducting layer 2 separates from the buffer layer 3. After the silver layer 1 and the REBCO superconducting layer 2 are wound around the metal tube 5 for one turn, the silver layer 1 of the second turn will be connected to the REBCO superconducting layer 2 of the first layer, that is, the silver layer 1 of the next turn is connected to the REBCO superconducting layer 2 of the previous turn; thus forming the first coil 6 on the metal tube 5.

[0044] (5) When the first coil 6 has been wound to the set number of turns, stop rotating the metal tube 5 and cut the REBCO tape;

[0045] Steps (2)-(5) are carried out in an oxygen atmosphere;

[0046] (6) Repeat steps (3)-(5) to wind a second coil on the metal tube 5. There is a gap between the second coil and the first coil 6, and the winding direction of the second coil is opposite to that of the first coil 6.

[0047] (7) Silver is plated on the circumferential outer surfaces of the first coil 6 and the second coil; thereby using the outermost REBCO superconducting layer 2 as an electrode;

[0048] (8) The first coil 6 and the second coil are subjected to oxidation annealing heat treatment, and the combination of the metal tube 5, the first coil 6 and the second coil is used as the double coil 7.

[0049] The parameters for oxidative annealing heat treatment include: oxygen partial pressure of 0.1–15 MPa, temperature of 350–600 °C, and time of 0.5–300 h;

[0050] (9) Repeat steps (1)-(8) to obtain multiple double-coil coils 7; and connect the multiple double-coil coils 7 sequentially to form a superconducting magnet; the first coil 6 or the second coil in the double-coil coil 7 is electrically connected to the first coil 6 or the second coil in the adjacent double-coil coil 7 through the superconducting tape 8 (refer to...). Figure 3 ).

[0051] In the description of this invention, it should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0052] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A method for winding a superconducting magnet, characterized in that, Includes the following steps: (1) Prepare REBCO tape without a metal protective layer; (2) Prepare a metal tube that is conductive and resistant to oxidation at high temperatures, and heat the metal tube with a heating device; the heating device is an electric heating rod, the metal tube is sleeved on the electric heating rod, and there is a gap between the inner wall of the metal tube and the electric heating rod; the electric heating rod heats the metal tube through thermal radiation. (3) The silver layer at the first end of the REBCO tape is brought into contact with the high-temperature outer surface of the metal tube, so that the silver layer is connected to the outer wall of the metal tube. (4) Clamp the base strip and buffer layer at the first end of the REBCO tape, and drive the metal tube to rotate through the driving device. The metal tube drives the silver layer and REBCO superconducting layer of the REBCO tape to rotate, while the REBCO superconducting layer separates from the buffer layer. After the silver layer and the REBCO superconducting layer are wound around the metal tube once, the silver layer of the second turn will be connected to the REBCO superconducting layer of the first layer, that is, the silver layer of the next turn is connected to the REBCO superconducting layer of the previous turn; a first coil is formed on the metal tube. (5) When the first coil has been wound to the set number of turns, stop rotating the metal tube and cut the REBCO tape; (6) Repeat steps (3)-(5) to wind a second coil on the metal tube, with a gap between the second coil and the first coil, and the winding direction of the second coil is opposite to that of the first coil. (7) Silver is plated on the circumferential outer surfaces of the first coil and the second coil; thereby using the outermost REBCO superconducting layer as an electrode; (8) Perform oxidation annealing heat treatment on the first coil and the second coil, and use the combination of the metal tube, the first coil and the second coil as a double coil.

2. The method for winding a superconducting magnet according to claim 1, characterized in that: It also includes step (9): repeating steps (1)-(8) to obtain a plurality of the double-coil coils; and connecting the plurality of double-coil coils in sequence to form a superconducting magnet; the first coil or the second coil in the double-coil coil is electrically connected to the first coil or the second coil in the adjacent double-coil coil through a superconducting strip.

3. The method for winding a superconducting magnet according to claim 1, characterized in that: The drive device is a geared motor, the metal tube is fixedly connected to the output shaft of the geared motor, and one end of the metal tube is coaxial with the output shaft.

4. The method for winding a superconducting magnet according to claim 1, characterized in that: The metal tube is made of silver.

5. The method for winding a superconducting magnet according to claim 1, characterized in that: The heating temperature of the metal tube in step (2) is 400-960℃.

6. The method for winding a superconducting magnet according to claim 1, characterized in that: Steps (2)-(5) are carried out in an oxygen atmosphere.

7. The method for winding a superconducting magnet according to claim 1, characterized in that: The conveying speed of the REBCO tape in step (4) is 0.001 to 1 m / min; the outer diameter of the metal tube is greater than 5 mm.

8. The method for winding a superconducting magnet according to claim 1, characterized in that: The parameters for the oxidation annealing heat treatment in step (8) include: oxygen partial pressure of 0.1-15 MPa, temperature of 350-600°C, and time of 0.5-300 h.

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