JP-7854999-B2 - Precursor wire for compound superconducting wires, compound superconducting wire, and method for rewinding compound superconducting wires

Inventors

• 杉本 昌弘
• 福島 弘之
• 廣瀬 清慈
• 浅見 大亮

Assignees

• 古河電気工業株式会社

Dates

Publication Date

20260507

Application Date

20220804

Priority Date

20210806

Claims (14)

1. A compound superconducting precursor section is composed of multiple compound superconducting precursor filaments and a first matrix precursor containing a first stabilizing material in which the multiple compound superconducting precursor filaments are embedded, A cylindrical reinforcing material portion is arranged on the outer periphery of the compound superconducting precursor portion and is composed of a plurality of reinforcing filaments and a second matrix containing a second stabilizing material in which the plurality of reinforcing filaments are embedded, The reinforcing material portion has a cylindrical stabilizing material portion made of a third stabilizing material, which is arranged on at least one of the inner and outer circumferences of the reinforcing material portion. A precursor wire for compound superconducting wires, wherein the aspect ratio Ab1 (Wb1/Tb1) of the width dimension Wb1 of the compound superconducting precursor portion to the thickness dimension Tb1 of the compound superconducting precursor portion in a cross section perpendicular to the longitudinal direction of the compound superconducting precursor portion is 1.80 or more.
2. The compound superconducting wire precursor wire according to claim 1, wherein the aspect ratio Ab1 is 11.00 or less.
3. The precursor wire for compound superconducting wires according to claim 1 or 2, wherein the aspect ratio Ab1 is 2.00 or more and 10.00 or less.
4. The compound superconducting wire precursor wire according to claim 1 or 2, wherein the total cross-sectional area of the compound superconducting precursor portion, the reinforcing material portion, and the stabilizing material portion in a cross section perpendicular to the longitudinal direction of the compound superconducting wire precursor wire is 0.40 mm² or more and 4.00 mm² or less.
5. The compound superconducting precursor wire according to claim 1 or 2, wherein the compound superconducting precursor filament is Nb, and a Sn diffusion prevention portion made of Nb or Ta or an alloy or composite thereof is further provided between the compound superconducting precursor portion and the reinforcing material portion.
6. The precursor wire for compound superconducting wires according to claim 1 or 2, wherein the first stabilizing material is copper or a copper alloy, the reinforcing filament is made of one metal selected from the group Nb, Ta, V, W, Mo, Fe, Ti, and Hf or an alloy composed of two or more metals, the second stabilizing material is copper or a copper alloy, and the third stabilizing material is copper or a copper alloy.
7. A compound superconductor section comprising a plurality of compound superconducting filaments containing a compound superconducting phase, and a first matrix containing a first stabilizing material in which the plurality of compound superconducting filaments are embedded, A cylindrical reinforcing material section is arranged on the outer circumference of the compound superconductor section and consists of a plurality of reinforcing filaments and a second matrix containing a second stabilizing material in which the plurality of reinforcing filaments are embedded, The reinforcing material portion has a cylindrical stabilizing material portion made of a third stabilizing material, which is arranged on at least one of the inner and outer circumferences of the reinforcing material portion. A compound superconducting wire in which the aspect ratio Ab2 (Wb2/Tb2) of the width dimension Wb2 of the compound superconducting portion to the thickness dimension Tb2 of the compound superconducting portion in a cross section perpendicular to the longitudinal direction of the compound superconducting portion is 1.80 or more.
8. The compound superconducting wire according to claim 7, wherein the aspect ratio Ab2 is 11.00 or less.
9. The compound superconducting wire according to claim 7 , wherein the aspect ratio Ab2 is 2.00 or more and 10.00 or less.
10. The compound superconducting wire according to claim 7, wherein the sum of the cross-sectional areas of the compound superconductor portion, the reinforcing material portion, and the stabilizing material portion in a cross section perpendicular to the longitudinal direction of the compound superconducting wire is 0.40 mm² or more and 4.00 mm² or less.
11. The compound superconducting wire according to claim 7, wherein the compound superconducting phase is Nb3Sn , and a Sn diffusion prevention portion made of Nb or Ta or an alloy or composite material thereof is further provided between the compound superconducting portion and the reinforcing material portion.
12. The compound superconducting wire according to claim 7 or 11, wherein the first stabilizing material is copper or a copper alloy, the reinforcing filament is made of one metal selected from the group Nb, Ta, V, W, Mo, Fe, Ti, and Hf or an alloy composed of two or more metals, the second stabilizing material is copper or a copper alloy, and the third stabilizing material is copper or a copper alloy.
13. The compound superconducting wire according to claim 7 or 11 , further comprising an electrical insulating portion containing resin on its outermost circumference.
14. A method for rewinding a compound superconducting wire according to claim 7 or 11 , When the compound superconducting wire is re-wound from the first winding member to the second winding member, A method for rewinding a compound superconducting wire, comprising extending the compound superconducting wire from the first winding member in the tangential direction to the first winding member, and winding the compound superconducting wire onto the second winding member while bending the compound superconducting wire in the same bending direction as when it was wound around the first winding member.

Description

This disclosure relates to a precursor wire for compound superconducting wires, compound superconducting wires, and a method for rewinding compound superconducting wires. The manufacture of superconducting magnets using compound superconducting wires, such as Nb3Sn , typically employs the wind-and-react (W&R) method, which involves winding a precursor wire for the compound superconducting wire onto a superconducting coil bobbin and then performing a heat treatment to create the compound. This is because the compound superconducting wire obtained through heat treatment is extremely susceptible to strain. When manufacturing large magnets, such as high-field, large-diameter magnets, using compound superconducting wires like Nb₃Sn by the wind-and-react method, the compound formation heat treatment for generating Nb₃Sn must be carried out in a furnace under vacuum or an inert gas atmosphere at a predetermined temperature of 600°C or higher, requiring the preparation of a large heat treatment apparatus appropriate to the magnet dimensions. Another method is the React-and-Wind (R&W) method, which involves winding coils using heat-treated compound superconducting wires such as Nb3Sn . The React-and-Wind method has the advantage of providing flexibility in the selection of materials for coil components such as winding frames and electrical insulation on the surface of the compound superconducting wire, as well as allowing adjustment of the strain on the compound superconducting wire after heat treatment. However, since the superconducting properties of compound superconducting wires such as Nb3Sn change depending on the strain state in the wire, it is necessary to carefully consider the strain state in the compound superconducting wire. For example, if a compound superconducting wire is damaged by strain caused by an external force applied to it after heat treatment, or if it experiences compressive residual strain due to differences in thermal contraction of the composite materials during cooling, or if it experiences tensile or lateral compressive strain due to electromagnetic force during coil operation, the superconducting properties of the compound superconducting wire, such as the critical current, may decrease. To date, many technological developments have been carried out to address this issue. For example, Patent Document 1 describes how to improve coil performance by forming a laminated conductor using a rectangular compound superconductor with magnetic field anisotropy of the critical current, thereby suppressing critical current anisotropy. However, since this does not improve the properties of the rectangular compound superconductor itself, the conductor design and the coil design using it are limited, making it difficult to achieve a significant improvement in critical current performance. Furthermore, Patent Document 2 describes a method for suppressing the flattening of the filament when processing it into a rectangular shape by softening the copper alloy surrounding the filament and arranging alumina-dispersed copper tubes, thereby suppressing the magnetic field anisotropy of the critical current density. However, this technique does not improve the critical current density of the flattened filament itself. Furthermore, Patent Document 3 discloses a processing method for obtaining a good filament shape in a rectangular wire. The conventional technologies represented by the above-mentioned Patent Documents 1 to 3 concern conductor structures that take into account the magnetic field anisotropy of the critical current of compound superconducting wires having a rectangular shape, in order to prevent a decrease in the current-carrying characteristics of the coil, and structures and processing methods to suppress abnormal deformation of the superconducting parts inside the compound superconducting wire that occur when it is processed into a rectangular shape. In particular, these technologies do not provide sufficient effect when applied to superconducting coils wound using the react-and-wind method, in which winding is performed after the heat treatment of compound formation. Therefore, in the react-and-wind method, it is necessary to take a large operating margin for the superconducting coil in consideration of the risk of a decrease in the performance of the superconducting coil, and the challenge is to suppress the increase in the amount of wire used and the increase in manufacturing costs. Furthermore, Patent Documents 4 to 6 describe compound superconducting wires suitable for the react-and-wind method, as well as practical winding methods for adjusting bending strain during winding. When applying the technologies described in Patent Documents 4 to 6 to actual coils and bending them to a small diameter, a method is employed to reduce the strain on the compound superconductor by reducing the outer diameter of the individual wires. As a result, the critical current per individual wire decreases, whic