REBCO high-temperature superconducting pie coil based on V2O3 film composite strip insulation and preparation method of REBCO high-temperature superconducting pie coil

Abstract

The invention provides an REBCO high-temperature superconducting cake coil based on V2O3 thin film composite strip insulation and a preparation method. The V2O3 thin film composite strip is formed by compounding a copper base strip and a V2O3 thin film; the REBCO high-temperature superconducting cake coil is formed by winding an REBCO high-temperature superconducting strip with a copper sheath and a V2O3 film composite strip in parallel, and also can be directly wound by an REBCO high-temperature superconducting strip with a V2O3 film coating; when the temperature is below 150K, V2O3 is an inter-turn insulating material of the REBCO high-temperature superconducting cake coil, and the REBCO high-temperature superconducting cake coil can be excited quickly; when the temperature exceeds 150K, the V2O3 is changed into a conductive material, the resistivity is reduced to 10 <-3 > omega.cm magnitude, the REBCO high-temperature superconducting cake coil is an uninsulated magnet, the quench propagation speed is accelerated, and the thermal stability of the high-temperature superconducting cake coil is improved.

Description

Technical Field

[0001] The invention belongs to the field of superconducting magnets, and in particular relates to a REBCO high-temperature superconducting pancake coil based on V2O3 thin film composite strip insulation and a preparation method thereof. Background Art

[0002] REBCO high-temperature superconducting magnets are expected to be widely used in energy and electricity, scientific instruments, and medical health. Although REBCO high-temperature superconducting magnets have higher magnetic field indicators, the quench propagation speed of REBCO high-temperature superconducting materials is very slow, generally 1~10 cm / s, which is two to three orders of magnitude smaller than the quench propagation speed of low-temperature superconducting materials. When local hot spots appear in high-temperature superconducting materials, there is a certain time delay for the quench signal to diffuse to the detectable measurement level, which makes it difficult to protect against quench. This is one of the main reasons why high-temperature superconducting materials have not replaced low-temperature superconducting materials on a large scale. It is of great significance to improve the stability of the magnet by quickly diffusing current and heat when the superconducting magnet quenches by improving the design of the inter-turn material of the superconducting magnet. If the inter-turn material of the superconducting magnet is an insulating material, the generation of eddy currents can be suppressed during the excitation process, which can ensure the stability of the magnetic field, but the current and heat are not easy to diffuse during the quench. If the turns are made of non-insulated conductive materials such as copper or stainless steel, the current and heat can diffuse quickly through the conductive layer during quench, which can solve the quench protection problem. However, the contact resistance of the conductive layer is small, and eddy currents are easily generated during normal operation, which makes the magnetic field unstable and increases the charging and discharging time. It can be seen that the turn-to-turn resistance has obvious shortcomings, whether it is insulating materials or metal materials, and it is difficult to meet the requirements of quench protection and magnetic field stability at the same time, resulting in quench protection being one of the main bottlenecks restricting the application of high-temperature superconducting materials for a long time.

[0003] A paper from Jeju National University in South Korea, "Investigation on characteristic of vanadiumtrioxide insulation mixed with metal powder for rare-earth barium copperoxide coils[Supercond. Sci. Technol. 37 (2024) 085012]", uses V2O3 as a filler and mixes it with polyvinylidene fluoride (PVDF 10wt%) and N-methylpyrrolidone (NMP 90wt%) to make a colloidal solution, which is then brushed on the surface of a superconducting tape. After a heat treatment at 90°C to volatilize the organic components, a V2O3-containing paint film with a thickness of about 180μm is formed on the surface of the superconducting tape. This method is simple to operate, but the uniformity is poor. Chinese invention patent application CN202111107898.9 uses high-temperature superconducting tape as a substrate to prepare an amorphous vanadium oxide film. Since the temperature of the high-temperature superconducting tape will be damaged when it exceeds 180°C, this patent uses a method of preparing an amorphous vanadium oxide film at room temperature without heating the substrate. However, the composition of the amorphous vanadium oxide film is complex and no insulating-metallic phase transition occurs at 150K. The resistivity is 10 at 150K. 2 The Ω·cm level makes it difficult to achieve rapid quench propagation and protection. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention provides a REBCO high-temperature superconducting pancake coil based on V2O3 thin film composite strip insulation and a preparation method thereof. When the temperature is below 150K, V2O3 is the inter-turn insulation material of the REBCO high-temperature superconducting pancake coil, and the REBCO high-temperature superconducting pancake coil can be rapidly excited; when the temperature exceeds 150K, V2O3 becomes a conductive material, and the resistivity drops to 10 -3 Ω·cm level, REBCO high temperature superconducting pancake coil is an uninsulated magnet, which accelerates the quench propagation speed and improves thermal stability.

[0005] In order to achieve the above object, the present invention adopts the following technical scheme:

[0006] A REBCO high-temperature superconducting pancake coil based on V2O3 film composite tape insulation, the REBCO high-temperature superconducting pancake coil is wound in parallel by a REBCO high-temperature superconducting tape with a copper sheath and a V2O3 film composite tape, the V2O3 film composite tape is composited by a copper base tape and a V2O3 film, the V2O3 film is attached to the front side of the copper base tape, and the back side of the copper base tape of the V2O3 film composite tape is in contact with the REBCO high-temperature superconducting tape with the copper sheath; the structure of the single-turn parallel tape is copper reinforcement tape, REBCO bare tape, copper reinforcement tape, copper base tape, and V2O3 film from inside to outside; when the temperature is below 150K, V2O3 is the inter-turn insulation material of the REBCO high-temperature superconducting pancake coil, and the REBCO high-temperature superconducting pancake coil can be quickly excited; when the temperature exceeds 150K, V2O3 becomes a conductive material, and the resistivity drops to 10 -3 Ω·cm level, REBCO high-temperature superconducting pancake coil is a non-insulated magnet, which accelerates the quench propagation speed and improves the thermal stability of the high-temperature superconducting pancake coil.

[0007] Furthermore, the REBCO high-temperature superconducting pancake coil is directly wound with a REBCO high-temperature superconducting tape with a V2O3 thin film coating. The REBCO high-temperature superconducting tape with a V2O3 thin film coating is made by brazing the reverse side of a copper base tape of a V2O3 thin film tape, a copper reinforcement tape and a YBCO bare tape, and the brazing temperature is lower than 250°C. The structure of a single-turn REBCO high-temperature superconducting tape with a V2O3 thin film coating is, from inside to outside, a copper reinforcement tape, a REBCO bare tape, a copper base tape and a V2O3 thin film.

[0008] The present invention also provides a method for preparing a V2O3 thin film composite strip. The V2O3 thin film composite strip is prepared by a medium frequency pulsed DC reactive magnetron sputtering process, comprising: selecting a high-purity V target and a copper base strip as the substrate; first, using the copper base strip as the substrate, sequentially using anhydrous ethanol, acetone, and deionized water for ultrasonic cleaning, and then using a high-pressure nitrogen gun for purging and air drying; the background vacuum is drawn to 5.0 × 10 -4 Below Pa, introduce an appropriate amount of argon gas, and first carry out pre-sputtering for 30 minutes; after completion, introduce high-purity Ar+ O2 mixed gas as reaction gas, control the flow rate of the mixed gas to maintain a certain vacuum degree in the sputtering chamber, the vacuum degree is 0.1-0.5Pa; use a medium-frequency pulsed DC power supply for sputtering coating, and control the corresponding film thickness by controlling the deposition time of the film.

[0009] Furthermore, the purity of the high-purity V target is 99.99%.

[0010] Furthermore, the purity of argon is 99.999%.

[0011] Furthermore, the purity of the Ar+O2 mixed gas is 99.99%, and the O2 content is 1-5%.

[0012] Furthermore, the substrate temperature is above 450°C.

[0013] Compared with other methods, the present invention has the following beneficial effects:

[0014] (1) Since the V2O3 film of the present invention is produced on the surface of a copper substrate, high temperature annealing or substrate heating processes can be used. The V2O3 film has a high purity and can produce an insulator-metal phase transition at 150K, thereby achieving rapid quench propagation and quench protection.

[0015] (2) The thickness of the V2O3 film of the present invention can be controlled within 1 μm. Compared with the V2O3 film prepared by the sol-gel method, the insulator accounts for a smaller proportion, which can realize the compact design of the REBCO high-temperature superconducting pancake coil. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of Example 1 of a REBCO high-temperature superconducting pancake coil based on V2O3 thin film composite strip insulation of the present invention;

[0017] Figure 2 This is a schematic diagram of Example 2 of a REBCO high-temperature superconducting pancake coil based on V2O3 thin film composite tape insulation according to the present invention. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in each embodiment of the present invention described below can be combined with each other as long as they do not conflict with each other. The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0019] like Figure 1 and Figure 2 As shown, a REBCO high-temperature superconducting pancake coil based on V2O3 thin film composite tape insulation of the present invention is wound in parallel by REBCO high-temperature superconducting tape with copper sheath and V2O3 thin film composite tape. The V2O3 thin film composite tape is composed of a copper base tape and a V2O3 thin film (i.e. Figure 1REBCO high-temperature superconducting pancake coils can also be directly wound with REBCO high-temperature superconducting tapes with V2O3 thin film coatings. When the temperature is below 150K, V2O3 is the inter-turn insulation material of REBCO superconducting magnets, and REBCO high-temperature superconducting pancake coils can be excited quickly; when the temperature exceeds 150K, V2O3 becomes a conductive material, and the resistivity drops to 10 -3 Ω·cm level, REBCO high-temperature superconducting pancake coil is a non-insulated magnet, which accelerates the quench propagation speed and improves the thermal stability of the high-temperature superconducting pancake coil.

[0020] Embodiment 1:

[0021] The REBCO high-temperature superconducting pancake coil is formed by parallel winding of REBCO high-temperature superconducting tape with copper sheath and V2O3 thin film composite tape into a pancake structure, and the reverse side of the copper base tape of the V2O3 thin film composite tape is in contact with the REBCO high-temperature superconducting tape with copper sheath; Figure 1 As shown in the figure, the structure of the single-turn parallel strip from the inside to the outside is copper reinforcement strip, REBCO bare strip (i.e. Figure 1 superconducting bare tape), copper reinforcement tape, copper base tape, and V2O3 film.

[0022] In Example 1, existing commercial REBCO high-temperature superconducting tape with copper sheath and V2O3 thin film composite tape can be used in parallel, without changing the production process of the existing REBCO high-temperature superconducting tape.

[0023] Embodiment 2:

[0024] The REBCO high-temperature superconducting pancake coil is made of REBCO high-temperature superconducting tape with V2O3 film coating directly wound into a pancake structure. The V2O3 film composite tape is composited with a copper base tape and a V2O3 film, and the V2O3 film is attached to the front of the copper base tape. The REBCO high-temperature superconducting tape with V2O3 film coating is made by brazing the back of the copper base tape of the V2O3 film composite tape, the copper reinforcement tape and the REBCO bare tape. The REBCO bare tape is located between the copper base tapes, and the brazing temperature is lower than 250°C. Figure 2 As shown in the figure, the structure of the REBCO high-temperature superconducting tape with a single turn of V2O3 thin film coating is a copper reinforcement tape, a REBCO bare tape (i.e. Figure 2 superconducting bare tape), copper base tape, and V2O3 thin film.

[0025] Compared with Example 1, Example 2 has one less copper reinforcement tape and a more compact structure, but the production process of the superconducting tape needs to be changed. It is necessary to use a V2O3 thin film composite tape copper base tape, a copper reinforcement tape and a REBCO bare tape for compounding.

[0026] The preferred process for preparing the V2O3 thin film composite strip in the above two embodiments is to use a medium frequency pulsed DC reactive magnetron sputtering process, and the method is as follows: a high-purity V target (99.99%) is selected, and the substrate is a copper base tape. First, the copper base tape substrate is ultrasonically cleaned in anhydrous ethanol, acetone, and deionized water in sequence, and then purged and air-dried with a high-pressure nitrogen gun. The background vacuum is drawn to 5.0 × 10 -4 Pa, introduce an appropriate amount of argon (99.999%), and first perform pre-sputtering for 30 minutes. After completion, introduce a certain amount of high-purity Ar+ O2 mixed gas (purity of 99.99%, O2 content of 1-5%) as a reaction gas, and control the flow rate of the mixed gas to maintain a certain vacuum in the sputtering chamber. Preferably, the substrate temperature is 450 ° C, and sputtering is performed, and the corresponding film thickness is controlled by controlling the deposition time of the film.

Claims

1. A REBCO high-temperature superconducting pancake coil based on V2O3 thin film composite tape insulation, characterized in that: The REBCO high-temperature superconducting pancake coil is wound in parallel by a REBCO high-temperature superconducting tape with a copper sheath and a V2O3 film composite tape. The V2O3 film composite tape is composed of a copper base tape and a V2O3 film. The V2O3 film is attached to the front side of the copper base tape, and the back side of the copper base tape of the V2O3 film composite tape is in contact with the REBCO high-temperature superconducting tape with a copper sheath. The structure of the single-turn parallel tape is copper reinforcement tape, REBCO bare tape, copper reinforcement tape, copper base tape, and V2O3 film from inside to outside. When the temperature is below 150K, V2O3 is the inter-turn insulation material of the REBCO high-temperature superconducting pancake coil, and the REBCO high-temperature superconducting pancake coil can be quickly excited. When the temperature exceeds 150K, V2O3 becomes a conductive material, and the resistivity drops to 10 -3 Ω·cm level, REBCO high-temperature superconducting pancake coil is a non-insulated magnet, which accelerates the quench propagation speed and improves the thermal stability of the high-temperature superconducting pancake coil.

2. A REBCO high temperature superconducting pancake coil based on V2O3 thin film composite tape insulation according to claim 1, characterized in that: REBCO high-temperature superconducting pancake coil is directly wound with REBCO high-temperature superconducting tape with V2O3 thin film coating. The REBCO high-temperature superconducting tape with V2O3 thin film coating is made by brazing the reverse side of the copper base tape of the V2O3 thin film tape, the copper reinforcement tape and the YBCO bare tape, and the brazing temperature is lower than 250°C; the structure of the single-turn REBCO high-temperature superconducting tape with V2O3 thin film coating is copper reinforcement tape, REBCO bare tape, copper base tape and V2O3 thin film from inside to outside.

3. A method for preparing a V2O3 thin film composite strip, characterized in that: The V2O3 thin film composite strip was prepared by medium frequency pulsed DC reactive magnetron sputtering process, including: selecting high purity V target and copper substrate. First, the copper substrate was used as substrate and ultrasonically cleaned in anhydrous ethanol, acetone and deionized water in sequence, and then purged and air-dried by high pressure nitrogen gun; the background vacuum was drawn to 5.0 × 10 -4 Below Pa, introduce an appropriate amount of argon gas, and first carry out pre-sputtering for 30 minutes; after completion, introduce high-purity Ar+ O2 mixed gas as reaction gas, control the flow rate of the mixed gas to maintain a certain vacuum degree in the sputtering chamber, the vacuum degree is 0.1-0.5Pa; use a medium-frequency pulsed DC power supply for sputtering coating, and control the corresponding film thickness by controlling the deposition time of the film.

4. The method for preparing a V2O3 thin film composite strip according to claim 3, characterized in that: The purity of high-purity V target is 99.99%.

5. The method for preparing a V2O3 thin film composite strip according to claim 3, characterized in that: The purity of argon is 99.999%.

6. The method for preparing a V2O3 thin film composite strip according to claim 3, characterized in that: The purity of Ar+O2 mixed gas is 99.99% and the O2 content is 1-5%.

7. The method for preparing a V2O3 thin film composite strip according to claim 3, characterized in that: The substrate temperature is above 450 °C.

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