JPS63299066A - Connecting method for superconductive cable - Google Patents

Abstract

PURPOSE:To obtain a connection section with the stably high probability that filaments meet by exposing superconductive filaments and dividing them in multiple groups and connecting a bundle of the superconductive filaments braided with these groups by solid phase connection or spot welding. CONSTITUTION:End sections of superconductive cables A, B are etched to expose superconductive filaments. They are then equally divided in three groups, e.g., a filament group (a) belonging to the superconductive cable A, a filament group (b) belonging to the superconductive cable B, and a filament group C belonging to the superconductive cables A, B. These three groups (a)-(c) are braided in turn, and the integrated filament bundle is solid phase-connected or spot-welded in the range of the connection length 11. The positional relationship among the three groups (a)-(c) is changed in the range of the connection length 11, thus the filaments of the groups (a)-(c) meet with the same probability. The meeting probability is thereby increased, and a stable connection section of superconductive cables is obtained.

Description

[Detailed Description of the Invention] (Aspects of the Invention) (Industrial Application Field) The present invention provides a method for connecting superconducting magnet-phase superconducting wires incorporated in nuclear fusion devices, single crystal pulling devices, MRl, magnetic levitation trains, etc. It is related to.

(Prior art) 1F Conventionally, when connecting multicore superconducting wires having tens to thousands of superconducting filaments, the base material, such as copper or aluminum, is etched and the superconducting filaments are exposed for a predetermined length. Then, the superconducting filaments were stacked or bundled as shown in FIGS. 5 and 6, and the bundles of superconducting filaments were welded in phase or spot welded at certain lengths. (References: Mitsuo Makino et al. “Solid phase joining of composite materials” National Welding Society Conference Lecture Summary No. 3
1st volume 10B, Masao Morita et al. “Superconductivity and connections of N6Ti multicore superconducting conductors” Institute of Electrical Engineers of Japan Still Image Study Group 5A-83-66
, 1983) (Problems to be Solved by the Invention) In the conventional connection method, tens to several thousand superconducting filaments to be connected to each other were simply bundled together. When superconducting filaments are connected to a flat plate, superconducting filament a belonging to conductor A and superconducting filament b belonging to conductor B are not necessarily directly connected. In many cases, superconducting filaments belonging to other conductive wires are connected through multiple superconducting filaments belonging to the same conductive wire.

Ru. In that case, the number of connection interfaces of the superconducting filament increases, and if the electrical resistance value per connection interface is constant,
The greater the number of interfaces, the higher the resistance value of the connection. If there is resistance in a part of the superconducting wire, it causes attenuation of the generated magnetic field in a superconducting magnet operated in persistent current mode, and it is difficult to connect to the inner layer of the superconducting coil, which has relatively poor heat dissipation, such as a resin-impregnated coil. If there is a connection, the temperature of the superconducting wire increases due to the DC resistance loss that occurs at the connection.
May cause quenching. Therefore, to improve the performance of superconducting magnets, it is essential to provide low-resistance and stable superconducting wire connections.

For this purpose, it is desirable that the probability that superconducting filaments belonging to different conducting wires are directly connected to each other, that is, the probability of encounter, is high and that the value thereof is stable.

An object of the present invention is to provide a method for connecting superconducting wires in which the probability of encountering superconducting filaments to be connected is stably high.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, in the connection method of the present invention, the superconducting filaments constituting the superconducting wire are exposed and divided into a plurality of groups. A bundle of interwoven superconducting filaments is connected by solid phase connection or spot welding.

(Function) In this way, the large number of superconducting filaments of both superconducting wires will surely come into contact with each other.

(Example) An example of the present invention will be described with reference to the drawings. In FIG. 1, the ends of two superconducting wires A and B are etched to expose a predetermined length of superconducting filament. The superconducting filaments are roughly equally divided into three groups: group a of superconducting filaments belonging to superconducting wire A, group b of superconducting filaments belonging to superconducting wire B, and group C of superconducting filaments belonging to superconducting wires A and B. Three groups are alternately knitted together, and the bundle of integrated superconducting filaments is wrapped in a metal cover and the range of connection length 11 is solid phase bonded (solid phase bonding means caulking, ultrasonic bonding, and diffusion bonding). ) or spot welding. In the case of spot welding, welding is performed at multiple locations at equal intervals.

By making such a connection, the positions of the three superconducting filament groups are swapped within the range of the connection length β1, so that a, b.

C The superconducting filaments of each group meet with the same probability. Furthermore, since the contact surfaces between each group are continuously shifted in the direction of the connection length, it is not possible for only the same superconducting filament in a certain group to always meet superconducting filaments in another group. .

Therefore, the probability that superconducting filaments will meet within one group nib and between each group becomes high, and its value is stabilized by keeping the number of groups, the weaving pitch f12, and the connection length pl the same.

When the number of superconducting filaments is large, it is preferable to increase the number of groups. Number of groups is 4, 5
FIGS. 2, 3, and 4 show the state in which two and six superconducting filaments are knitted together, respectively. As is clear from the figure, superconducting filaments can be knitted without any problem if the filaments are divided into groups of three or more, regardless of whether the number of groups is odd or even.

In addition, in the example described above, the direction of the current flowing through the connection is switchback (returning to the opposite direction to the direction it once went), but in other cases, the direction of the current flowing through the connection is straight (in one direction). It is also possible to knit together the superconducting wires A and B that are to be connected so that they face each other so that

[Effects of the Invention] According to the present invention, it is possible to increase the probability that superconducting filaments to be connected are directly connected to each other without using other superconducting filaments, that is, the probability of encounter, and to stabilize the value. Therefore, a stable superconducting wire connection with low electrical resistance can be provided.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a connecting portion of a superconducting wire according to a connecting method according to an embodiment of the present invention, and FIGS. 2, 3, and 4 are plan views of a connecting portion of a superconducting wire according to other embodiments. Figure 5 is a plan view of the connection part of a conventional superconducting wire, and Figure 6 is the Vl - of Figure 5.
FIG. 3 is a cross-sectional view taken along line Vl. A, B...Superconducting wire a...Superconducting filament b belonging to superconducting wire A...
・Superconducting filament C belonging to superconducting wire B...Superconducting filament C belonging to superconducting wires A and B...Connection length β2...Superconducting filament weaving pitch Agent Patent attorney Noriyuki Chika Yudo Daishimaru Ken Figure 1 Figure 4

Claims (1)

[Claims] A method for connecting a superconducting wire, which comprises exposing the superconducting filaments constituting the superconducting wire, dividing the superconducting filaments into a plurality of groups, and connecting the bundles of superconducting filaments made by interweaving these groups by solid-phase joining or spot welding.