JPH06162836A - Composite superconductor and superconducting coil - Google Patents

Abstract

PURPOSE:To lower the composite specific resistance at very low temperatures of a composite material having high purity aluminum as a stabilizer. CONSTITUTION:A composite superconductor 20 is formed by joining a superconducting wire 10 and a composite material 21 together using solder 15, the composite material 21 comprising a tape-shaped copper member 12 joined to the broad surface of high purity aluminum 11 of rectangular cross section. When in use the composite superconductor 20 is disposed with the broad surface of the high purity aluminum 11 being parallel to an external magnetic field H. By disposing the composite superconductor in this way the composite specific resistance of the composite material 21 can be reduced significantly and the specific resistance of the whole conductor can be approximated to that of the high purity aluminum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite superconducting body and a superconducting coil, and particularly to a composite superconducting body which uses a high-purity aluminum material as a stabilizing material and can maintain excellent stability in a high magnetic field. And improvement of the superconducting coil.

[0002]

2. Description of the Related Art Conventionally, as a superconducting body used for large-scale superconducting equipment, for example, large-scale superconducting magnets for nuclear fusion, energy storage, accelerators, etc., a multi-core structure superconducting wire and a stabilizer are combined with solder. Superconductors are known.

Copper or aluminum is generally used as a stabilizer for the above-mentioned composite superconducting body, but copper has a higher strength than aluminum and a small strength difference from the superconducting filament. Although it has excellent workability and good solderability, it has a large resistivity at cryogenic temperature, whereas aluminum has the advantage that it has a lower resistivity at cryogenic temperature than copper. However, since the strength is small and the strength difference from the superconducting filament is large, it is difficult to process, and the solderability is poor and there is a problem in forming a composite with the superconducting wire.

However, high-purity aluminum is
The increase of the magnetoresistive effect in a high magnetic field is small compared to copper,
Therefore, since the specific resistance under a high magnetic field is small and the stability is excellent, it is advantageous to use aluminum as a stabilizing material as a conductor for a high magnetic field and from the viewpoint of superconducting properties.

In order to overcome the above-mentioned drawbacks of aluminum, it is generally practiced to form a composite of aluminum and copper with a superconducting wire.

As such an aluminum-stabilized superconducting body, various monolithic, housing-type, twisted-type or composite-type composite superconducting bodies have been investigated.

The above-described monolith-type superconducting body has a structure in which a copper-coated aluminum material is arranged inside a superconducting wire having a copper matrix. The housing-type superconducting body is composed of two copper members having a concave cross section. The housing has a structure in which the superconducting wire having a copper matrix and a copper-coated aluminum material are arranged inside each other, and the stranded wire type superconductor is a superconducting wire having a copper matrix and a copper-coated aluminum wire. It has a twisted structure. Further, the composite type superconducting body is a composite of a wire material obtained by twisting superconducting wires having a copper matrix, compression-molding the superconducting wires, and a copper-coated aluminum material.

In the above composite superconducting body, the superconducting wire and the copper-clad aluminum material are generally integrated by being joined by solder.

According to the results of experiments conducted by the inventors of the present invention, the specific resistance of high-purity aluminum is significantly smaller than the specific resistance of copper at zero magnetic field, and has a substantially constant value in the range of 2 to 6 T (Tesla). On the other hand, the specific resistance of copper is significantly larger than that of aluminum in a zero magnetic field, and its value sharply rises in the range of 2 to 6 T (Tesla). For example, at 6T (4.2K), the specific resistance is about 10 times or more that of high-purity aluminum (Japanese Patent Application No. 3-398).
No. 52).

Therefore, it is expected that the composite specific resistance of the composite superconductor can be remarkably reduced by substituting a part of copper as the stabilizer for the copper-coated aluminum material.

[0011]

However, if the high-purity aluminum material is coated with copper and is simply combined with the superconducting wire, or if it is simply placed inside the superconducting wire, each of them has a specific resistance. It has been measured that the value is significantly larger than the calculated combined resistivity. For example, in a composite superconducting body in which a diffusion barrier of niobium is arranged outside a high-purity aluminum wire having a circular cross section, and further a multi-core superconducting wire and a stabilized copper are sequentially arranged, at the cryogenic temperature It has been found that the specific resistance characteristic is not obtained and the specific resistance characteristic is intermediate between that of high-purity aluminum and copper (the 37th low temperature engineering presentation B1-4).

Therefore, there is a problem that the effect of using the high-purity aluminum material cannot be exhibited. The present invention has been made to solve the above problems, and significantly improves the specific resistance characteristics at extremely low temperatures when high-purity aluminum is used as a stabilizing material, and particularly exhibits excellent stability in a high magnetic field. It is an object of the present invention to provide a composite superconducting body that can be maintained and a superconducting coil using the same.

[0013]

In order to achieve the above object, the present invention provides a composite superconducting body in which a superconducting wire having a multi-core structure and a stabilizing material are joined, at least outside the high-purity aluminum material. A stabilizer having a cross-sectional shape coated with copper except for a part is used.

In the above composite superconductor, it is preferable that the stabilizer is formed by contacting copper with a wide surface of a high-purity aluminum material having a rectangular cross section.

In the composite superconducting body of any structure, when the composite superconducting body is used so that the axial direction of the stabilizing material and the plane including the removed portion of the copper clad material are positioned in the direction of the magnetic field, the composite specific resistance is obtained. Can be reduced.

In particular, when a high-purity aluminum material or a high-purity aluminum tape having a rectangular cross section is used as a stabilizer, it is possible to form a coil by using a composite material in which copper is contacted only in the width direction. It is possible to reduce the combined specific resistance.

From the above, in the superconducting coil of the present invention, a superconducting wire having a multi-core structure and a stabilizing material having a cross-sectional shape in which copper is brought into contact with a wide surface of a rectangular high-purity aluminum material are joined,
The high-purity aluminum material is wound such that the wide surface is parallel to the axial direction of the coil or the direction of the magnetic field formed by the coil.

[0018]

In the composite superconducting body and the superconducting coil having the above-described structure, by using a stabilizing material having a cross-sectional shape in which at least a part of the high-purity aluminum material is coated with copper, the superconducting body is synthesized. Although the specific resistance can be remarkably reduced, this phenomenon is based on the findings of the present inventors that the composite specific resistance of the superconducting body depends on the shape of the copper-clad aluminum material and the arrangement with respect to the external magnetic field.

FIG. 7 shows the dependence of the specific resistance of the high-purity aluminum material and the copper-coated high-purity aluminum material at an extremely low temperature (4.2K) on the external magnetic field. In FIG. 7, A is the outer diameter φ1.446 mm. High circularity aluminum material with a circular cross section, and B is an outer diameter φ1.61mm and the area ratio is Al: C.
u = 1: 0.239 shows a copper-coated high-purity aluminum material having a circular cross section, both of which are the results measured at a current of 100 A. In this case, the result that the variation of the specific resistance value due to the wire diameter is small is also obtained. That is, by coating a high-purity aluminum material with copper, the composite specific resistance thereof is significantly increased from the theoretical value. When a part of the copper-clad material of copper-clad high-purity aluminum material with a circular cross section is removed, its combined resistivity fluctuates depending on the area of the removed part and the positional relationship with respect to the external magnetic field. When the copper coating material showing a value in the range and positioned perpendicular to the external magnetic field is partially removed, the combined specific resistance approaches the specific resistance of the high-purity aluminum material.

On the other hand, FIG. 8 shows the dependence of the specific resistance of a composite material having a rectangular cross section at an extremely low temperature (4.2 K) on the external magnetic field, and C and C'in the figure show a cross section of 0.4. The figure shows a case where 0.05 mm thick copper 2, 2'is joined to a wide surface of a high-purity aluminum material 1 of × 1.9 (mm), and D and D'in the figure are cross sections of 0.5 × 2.0
It shows a case where a high-purity aluminum material 3 (mm) is coated with copper 4 having a thickness of 0.05 mm. The positional relationship of the sample with respect to the external magnetic field of these measured values is shown in FIG.
It is shown in (b) and FIGS. 10 (a) and (b). From this result, in the case of a composite material with a rectangular cross section, by arranging the wide surface of the high-purity aluminum material so that it is parallel to the direction of the external magnetic field, its combined resistivity decreases, especially in the direction perpendicular to the external magnetic field. It is clear that the composite specific resistance of the sample C ′ in which copper is not arranged is close to the specific resistance of high-purity aluminum.

Therefore, when a superconducting coil is manufactured using a composite superconducting body in which a copper-bonded composite material and a superconducting wire are bonded to the wide surface of the high-purity aluminum material, as shown in FIG. 9 (b). By arranging the wide surface so as to be parallel to the axial direction of the coil or the direction of the magnetic field formed by the coil, the combined specific resistance thereof is significantly lowered, and the quenching resistance can be improved.

[0022]

EXAMPLES Examples of the present invention will be described below.

FIG. 1 is a sectional view of an embodiment of the composite superconducting body of the present invention. 10 is a superconducting wire, 11 is a high-purity aluminum material, and 12 is a copper member.

The superconducting wire 10 comprises a large number of filaments 14 made of Nb ₃ Sn or Nb-Ti alloy in a copper matrix 13. For example, a copper-coated Nb-Ti wire is formed into a hexagonal cross section. A large number of these are housed in a copper tube, which is subjected to surface-reduction processing and molded into a rectangular shape.

The composite superconducting body 20 is composed of the superconducting wire 10
And a composite material 21 in which a tape-shaped copper member 12 is bonded to a wide surface of a high-purity aluminum material 11 having a rectangular cross section, and the composite material 21 is bonded by solder 15.

The composite material 21 is obtained by forming a copper-coated aluminum material into a rectangular cross section and then mechanically or chemically removing the copper member in the thickness direction.

As shown in the figure, this composite superconductor 2
0 is arranged such that the wide surface of the high-purity aluminum material 11 is parallel to the external magnetic field H and is used. That is, as shown in FIG. 2, a composite superconducting body 20 provided with an insulating coating.
′ Is wound around the winding frame 23 so that the axial direction of the coil 22 and the wide surface of the high-purity aluminum material 11 are parallel to each other to form a magnet. By arranging the composite superconducting body 20 'in this way, the specific resistance of the composite material 21 can be remarkably reduced, and the specific resistance of the entire conductor can be brought close to the specific resistance of the high-purity aluminum material.

FIG. 3 shows another embodiment of the composite superconducting body 30 of the present invention, in which both sides of a composite material 21 in which a copper member 12 is joined to a wide surface of a high purity aluminum material 11 having a rectangular cross section, It has a structure in which superconducting wires 10 and 10 having a multi-core structure having a rectangular cross section are arranged and joined with solder 15.

FIG. 4 shows a composite superconducting body 31 of the present invention.
Another embodiment of the present invention, in which the concave portions of the copper housing members 32, 32 'having a concave cross-section are arranged to face each other, the superconducting wire 10 is accommodated in the concave portions, and joined by solder 15 The composite materials 21 and 21 are arranged on both sides of the wire 33 and joined by the solder 15.

FIG. 5 is a sectional view showing another embodiment of the composite superconducting body of the present invention. The composite superconducting body 3 is shown in FIG.
5 is a plurality of multifilamentary superconducting wires 36 having a circular cross section, which are twisted on the outside of a composite material 21 in which a tape-shaped copper member 12 is joined to a wide surface of a high purity aluminum material 11 having a rectangular cross section. And the multi-core superconducting wire 36 are joined by the solder 15.

The above-mentioned composite superconductors 30, 31, and 35 are also arranged and used so that the wide surface of the high-purity aluminum material 11 is parallel to the external magnetic field H.

In the above embodiment, the same parts are designated by the same reference numerals.

In each of the above examples, the composite material is formed by joining the tape-shaped copper member to the wide surface of the high-purity aluminum material having a rectangular cross section, but the structure of the composite material is not limited to this. Other structures can be used as long as they have a cross-sectional shape in which copper is coated on the outside of at least a part of pure aluminum. FIG. 6 shows such an example. FIG. 6A shows a high-purity aluminum material 40 having a circular cross section.
Further, FIG. 2B shows a case where copper 42 and 42 'are joined together by using a high-purity aluminum material 41 having a rectangular cross section, except for a part of positions facing each other. Also in this case, the external magnetic field H and the line connecting the removed copper portions are arranged substantially parallel to each other. However, compared with the case shown in FIGS. 1, 3, 4 and 5, the combined specific resistance increases.

[0034]

As described above, according to the present invention, by using a stabilizing material having a cross-sectional shape in which copper is coated on the outside of a high-purity aluminum material except at least a part thereof, it is possible to achieve a low temperature. Since it is possible to reduce the combined specific resistance at 1, the stability in a high magnetic field is improved, and a composite superconductor and a superconducting coil having excellent quenching resistance can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a composite superconducting body of the present invention.

FIG. 2 is a sectional view showing an embodiment of the superconducting coil of the present invention.

FIG. 3 is a sectional view showing another embodiment of the composite superconducting body of the present invention.

FIG. 4 is a sectional view showing another embodiment of the composite superconducting body of the present invention.

FIG. 5 is a sectional view showing another embodiment of the composite superconducting body of the present invention.

FIG. 6 is a cross-sectional view showing another shape of the stabilizing material used in the composite superconducting body of the present invention.

FIG. 7 is a graph showing the dependence of the specific resistance of the high-purity aluminum material and the copper-coated high-purity aluminum material at an extremely low temperature on the external magnetic field.

FIG. 8 is a graph showing the dependence of the resistivity of a composite material having a rectangular cross section at an extremely low temperature on an external magnetic field.

9A and 9B are samples C and C'of FIG. 8, respectively.
FIG. 5 is a cross-sectional view showing the positional relationship of the to the external magnetic field.

10A and 10B are samples D and D of FIG. 8, respectively.
Sectional drawing which shows the positional relationship with respect to the external magnetic field of '.

[Explanation of symbols]

1, 11 ... High-purity aluminum material 2, 2 ', 4 ... Copper 10 ... Superconducting wire 12 ... Copper member 15 ... Solder 20, 20', 30, 31, 35 ... Composite superconducting body 21 ... …… Composite material 22 ………… Coil 23 ………… Reel 31 ………… Multi-core superconducting wire A ………… High-purity aluminum material B ………… Copper coated high-purity aluminum material C, C ′… High rectangular cross section Pure aluminum material A sample with copper bonded to a wide surface. D, D '... A sample obtained by coating a high-purity aluminum material having a rectangular cross section with copper.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Nobuo Aoki No. 1-1 Oda Sakae, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture, Showa Electric Wire & Cable Co., Ltd. (72) Tomoyuki Kumano 2 Sakae Oda, Kawasaki-ku, Kawasaki-shi, Kanagawa 1-1-1 Showa Electric Cable Co., Ltd. (72) Inventor Masashi Hakada 2-1-1 1-1 Oda Sakae, Kawasaki-ku, Kawasaki-shi, Kanagawa Kanagawa Prefecture Satoshi Hanai Tsurumi Yokohama City, Kanagawa Prefecture 2-4 Suehiro-cho, Toshiba Keihin Office (72) Inventor Yoshihiro Wachi Yoshihiro Wachi 2-4 Suehiro-cho, Tsurumi-ku, Yokohama-shi, Kanagawa Toshiba Keihin Office (72) Inventor Murase Aki Kawasaki, Kawasaki, Kanagawa Komukai Toshiba Town No. 1 Incorporated Toshiba Corporation Research Institute (72) Inventor Tsutomu Fujioka 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo The inner

Claims (3)

[Claims] 1. A composite superconducting body comprising a superconducting wire having a multi-core structure and a stabilizing material bonded to the superconducting wire, wherein the stabilizing material is provided outside the high-purity aluminum material except at least a part thereof. A composite superconducting body having a cross-sectional shape coated with copper. 2. The composite superconducting body according to claim 1, wherein the stabilizing material is formed by contacting copper with a wide surface of a high-purity aluminum material having a rectangular cross section. 3. A superconducting coil formed by winding a composite superconducting body comprising a superconducting wire having a multi-core structure and a stabilizing material bonded to the superconducting wire, wherein the stabilizing material is a high-purity aluminum material having a rectangular cross section. Of the high-purity aluminum material is arranged such that the wide surface of the high-purity aluminum material is parallel to the axial direction of the coil or the direction of the magnetic field formed by the coil. .