JPH05109324A - Superconductive conductor - Google Patents

Abstract

PURPOSE:To improve the required current density of a large-current capacity conductor comprising oxide superconducting wire-rods used therein. CONSTITUTION:For superconducting wire-rods 1 composing an assembled conductor are used wire rods of two kinds consisting of a type A and a type B, for example, tape-shaped wire-rods 1a and 1b each comprising an Ag coat 3 applied to a core 2 made of a Tl group oxide superconductor. Then 50 sheets of the type A wire-rods 1a are used on each of two surface-sides of the assembled conductor and 50 sheets of the type B wire-rods 1b on the inner side thereof to be laminated upon one another, and then a small-diameter lead-wire 4 is wound round the periphery of the resulting laminate to assemble these wire-rods into the conductor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aggregate conductor using an oxide-based superconducting wire.

[0002]

2. Description of the Related Art Superconducting wires are sometimes assembled into a conductor for the purpose of increasing the current capacity of the superconducting conductor.

The current density (Jc) that can flow in the superconducting wire changes depending on the magnetic field (B). The Jc-B characteristics differ depending on the material or temperature of the superconducting wire, and even the materials of the same system may differ greatly depending on the heat treatment conditions and the difference in additives. Also, although oxide-based superconducting wire is currently under development, not only the Jc-B characteristics but also the resistance value under the current density of Jc or more due to the difference in additives, compounding ratio, heat treatment conditions, surface-reduction processing conditions, Is also different.

[0004]

It is known that the critical current (Ic) of an oxide-based superconducting wire decreases even in a weak magnetic field of several mT. Therefore, even when the oxide-based superconducting wires are assembled to increase the current capacity, the self magnetic field value due to conduction of the conductor restricts the Ic as the assembled conductor.

When designing such a superconducting conductor, in many cases, the same magnetic field-critical current density (Jc-B characteristic) is used for each wire. However, the self-magnetic field distribution in the conductor cross section is not uniform, and bundling wires having the same Jc-B characteristics is not the best method for increasing Ic as a collective conductor.

An object of the present invention is to provide a superconducting conductor capable of improving the required current density of a large-current conductor using an oxide-based superconducting wire.

[0007]

The gist of the present invention is, as a method of constructing an oxide-based superconducting wire aggregate conductor, a plurality of types of oxide-based superconducting wires having different Jc-B characteristics depending on the self-magnetic field distribution applied during operation. The cross section was constructed using.
That is, the high magnetic field low current type wire rod is used at the position of the cross section where the self magnetic field becomes large, and the low magnetic field high current type wire rod is arranged at the position of the cross section where the self magnetic field becomes small.

In this case, as the superconducting wire, for example, Y
-Ba-Cu-O, Bi-Sr-Cu-O, Bi-Sr
-Ca-Cu-O, Tl-Ba-Cu-O, Tl-Ba
-Ca-Cu-O, Tl-Sr-Ca-Cu-O, La
-Na-Cu-O, La-Ba-Cu-O, La-Sr
-Cu-O and other oxide-based superconductors with Ag, Cu, Al,
Those coated with a normal conductor such as an alloy mainly containing them are used, but a plurality of types having different Jc-B characteristics are used depending on the magnetic field distribution of the conductor cross section, for example, in a place where the magnetic field is large. A wire having a large Jc in a high magnetic field is used, and a wire having a large Jc in a low magnetic field is arranged in a place where the magnetic field is small.

[0009]

[Function] Since wires having different Jc-B characteristics are arranged according to the magnetic field distribution of the conductor cross section, the wire configuration is optimized,
The superconducting critical current density as a superconducting wire aggregate conductor can be improved.

[0010]

EXAMPLE FIG. 1 shows the structure of a superconducting collective conductor prototyped according to the present invention. Here, there are two types of tape-shaped wire 1a of type A and type B as superconducting wire.
And 1b, for example, a core 2 made of a Tl-based oxide superconductor coated with Ag-made coating 3 was used. The individual tape-state wire rods 1a and 1b all have the same dimensions, with a thickness of 0.15 mm, a width of 2.7 mm, and a superconducting space factor of about 30%. 25 pieces of tape-shaped wire rods 1a are arranged and 50 pieces of type-B wire rods 1b are arranged inside and laminated, and then a conductor wire 4 having a small diameter is wound and assembled.

In this case, type A wire 1a and type B
The manufacturing conditions of the wire rod 1b were the same until the heat treatment at 900 ° C. for 50 hours was repeated four times, and thereafter, only for the type A wire rod 1a, the heat treatment at 800 ° C. for 20 hours was added once.

FIG. 4 shows the Jc-B characteristics of the type A and type B wire rods 1a and 1b manufactured as described above. Type A and type B have different characteristics, and Jc has a large type A wire rod in a high magnetic field and a large type B wire rod in a low magnetic field.

The maximum magnetic field of the above-mentioned assembly conductor is about 20 mT on the surface. However, a few mT inside the conductor
However, a larger current can be applied by using the type B wire rod than by using the type A wire rod on the inside.

The critical current (I
When c) was actually measured, it was 320 A, and it was confirmed that Ic was larger than that of the assembly conductor (280 A) in which only 100 sheets of the type A wire 1a were laminated.

FIG. 2 shows another example of the superconducting collective conductor,
A plurality of oxide-based superconducting wire rods are provided around the hollow pipe 6 made of a copper stabilizing material, the wire rod 5a of type A and the wire rod 5 of type B.
b arranged alternately, and assembled with low temperature solder 7 etc.,
By flowing a cryogen such as liquid nitrogen or liquid helium in the hollow pipe 6, the cooling effect can be enhanced.

FIG. 3 shows another example of the collective conductor. For example, a plurality of tape-shaped oxide-based superconducting wires 1 are typed inside a stabilizing material 8 in which a copper plate is formed in a U shape.
Wire rod 1b, and type B wire rod 1b on the outside, respectively, are housed in a laminated state, and integrated by low-temperature solder 7 or the like to be joined via a tape-shaped electric insulating layer 9 to form a current reciprocating conductor. Is.

[0017]

As is apparent from the above description, according to the present invention, it is possible to improve the superconducting critical current density as a superconducting wire aggregate conductor by optimizing the strand configuration.
It is useful as a conductor for superconducting power cables and current leads.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an outline of one embodiment of a superconducting conductor according to the present invention.

FIG. 2 is an explanatory view showing another example of a superconducting conductor.

FIG. 3 is an explanatory view showing another example of a superconducting conductor.

FIG. 4 is a Jc-B characteristic diagram.

[Explanation of symbols]

 1a and 5a Type A oxide superconducting wire 1b and 5b Type B oxide superconducting wire 2 Oxide superconductor core 3 Ag coating 4 Conductive wire 6 Hollow pipe 7 Low temperature solder 8 Stabilizer 9 Electrical insulating layer

Claims (1)

[Claims] 1. A superconducting conductor comprising a plurality of oxide-based superconducting wire rods including a coating material made of a normal superconducting metal, wherein a high magnetic field, low current type element wire is provided at a position where the self magnetic field of the conductor cross section becomes large. A superconducting conductor characterized by arranging and arranging a low magnetic field and high current type element wire at a position where the self magnetic field becomes small.