JPH03194874A - Connection method for superconductor - Google Patents

Abstract

PURPOSE:To reduce heat generated in connected portions of superconductors and obtain the connected portions of small size by giving an inclination to the exposed length of superconductive wires, and joining them in order from shorter ones to longer ones. CONSTITUTION:Wire rods 1 of two superconductors 10 arranged in parallel are connected one to one or plural to plural. The wire rods 1 become longer toward the outside from the inside of the two superconductors 10, and are joined in order from short ones to long ones to each other to obtain a crest joined shape. A supersonic junction method is used as the method. Namely, the inclined length of the superconductive wires 1 enables the superconductive wires to be securely joined with excellent operability. Therefore, Joule heat generated in a connected portion 7 can be restrained to be small, and moreover, the length of the connected portion 7 can be set suitably.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a method for connecting four cable-in-conduit superconductors.

(Conventional technique v#) If large superconducting magnets used in nuclear fusion devices and the like that generate a high magnetic field are manufactured using a forced cooling method, it is possible to improve the mechanical strength of the conductor and increase the current density. Furthermore, devices using superconducting magnets can also be downsized.

When using four superconducting bodies using forced cooling, it is desirable to increase the contact area between the superconducting wire and helium in order to increase the stability of the conductor.The most suitable conductor for this purpose is the one shown in Figure 6. It is a cable-in-conduit conductor. In the figure, a large number of superconducting wires 1 are shafted in a conduit 2 made of a non-magnetic metal such as stainless steel, and helium is contained in the superconducting wires 1 in the conduit 2.
The structure is such that the air flows through the gap (helium flow path) 3 between the two for cooling. Here, the cross section of the conductor is not necessarily circular.

Long cable-in-conduit conductors are manufactured by bending non-magnetic thin plates using rollers, etc., and performing continuous seal welding while inserting superconducting wires, but there is naturally a limit to the length that can be manufactured. However, when manufacturing a superconducting coil, it is generally manufactured while connecting the conductors by a method such as soldering the superconducting wires 1 together and covering the outside with a pipe 4, as shown in Figure 7. . In the case of such a joining method, Joule heat generation at the connection portion increases, leading to a decrease in the performance of the superconducting coil. Also.

This heat generation can sometimes quench the coil.

Another method of solder bonding is solid phase diffusion bonding.

This method directly joins superconducting wires together by mechanically applying pressure while heating them to several hundred degrees in a vacuum. To join four superconducting cable-in-conduit bodies using this method, the cable-in-conduit cables must be placed one at a time or in a bundle of several cables and placed in a vacuum heating furnace and connected. In order to connect several hundred wires, a considerably large area is required for the solid-phase diffusion bonding equipment. In other words, the length of the joint becomes longer than necessary, the device becomes larger, and the cost of manufacturing the device also increases.

(Problem M to be solved by the invention) When connecting four superconducting bodies, joining methods such as solid-phase diffusion bonding of superconducting wires and soldering are used. In order to suppress Joule heat generation, soldering requires a considerable length. Furthermore, if the solder is not filled between the wires without any gaps, the contact will be poor and the amount of heat generated will increase, causing quenching. This not only causes a decline in the performance of the superconducting coil, but also degrades the functionality of the entire device using the superconducting coil.

Furthermore, in the case of solid-phase diffusion bonding, a considerably large space is required for bonding, resulting in an increase in the length of the bonded portion.

The object of the present invention is to provide cable-in-conduit superelectric 44
To reduce the amount of heat generated at a connecting part of a body and to provide a compact connecting part.

[Structure of the invention]

(Means for Solving the Problem) Four superconducting wires arranged in parallel are connected one by one or a plurality of wires at a time. The length of the wire is adjusted from the inside to the outside of the two conductors. The wires are joined in order from short to long wires, and the shape after joining becomes a mountain. Ultrasonic bonding is used as the bonding method.

(Function) By slanting the length of the superconducting wires, all the superconducting wires can be connected reliably with good workability. Since the wires are reliably joined by ultrasonic bonding, it is possible to reduce the amount of heat generated during energization.

(Example) (Configuration of Example) An example of the present invention will be described below with reference to FIGS. 1 to 5. In Figure 1, 1 is a superconducting wire, 2 is a superconducting wire 1
It is a conduit that stores. The length of the superconducting wire 1 is adjusted stepwise from the inside to the outside. 6 Ultrasonic bonding consists of arranging two superconducting bodies with such a structure in parallel and ultrasonically bonding them with the longest ones on the outside in order from the shortest one on the inside.
This is a method in which pressure is mechanically applied to the joint in the atmosphere and bonded using ultrasonic vibrations. The shape after joining becomes a mountain shape. The joining situation is shown in Figure 4.5. After the joining is completed, the pipe 4 is covered and joined to the conduit 2 by welding. This pipe 4 is provided with refrigerant supply and discharge ports 5 and 6.

(Operation of the embodiment) By changing the length of the superconducting wires to be connected in a stepwise manner, connections can be made sequentially from the short inner part to the long outer part. By bonding with ultra-long waves, the wires can be reliably bonded, and the heat generated during energization can be suppressed to a small level. can be bonded, so the amount of heat generated can be kept low. Furthermore, the connection length can be optimized by adjusting the length of the wire in a stepwise manner.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to suppress Joule heat generation in the connecting portion to a small level, and to make the length of the connecting portion to be appropriately compact.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of a connection part to which the connection method of the embodiment of the present invention is applied, Figs. 2 and 3 are diagrams in which the length of the superconducting wire is adjusted in the above embodiment, and Figs. 4 and 5. 6 is a sectional view of a cable-in-conduit conductor having a circular cross section, and FIG. 7 is a diagram illustrating a conventional solder connection method.

Claims (3)

[Claims] (1) In a connection method in which a superconductor having a superconducting wire is connected in a conduit and folded back to form an electric path, the exposed length of the superconducting wire is sloped, both short wires are joined in order, and a pipe is covered. A method for connecting a superconductor, characterized by tightly sealing it with a conduit of the superconductor. (2) The method for connecting superconducting conductors according to claim (1), wherein the superconducting wires are joined by ultrasonic waves. (3) The method for connecting superconducting conductors according to claim (1), wherein the pipe has a refrigerant supply/discharge port.