JPH048900B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for joining superconducting wires, and is particularly suitable for joining superconducting wires each having a plurality of superconducting filaments embedded in a stabilizing material. The present invention relates to a method for joining superconducting wires.

[Conventional technology]

In recent years, superconducting wires have been increasingly used in devices that require large currents to flow, such as coils in nuclear fusion devices, but there is a limit to the length of these superconducting wires. When used in equipment,
It is necessary to connect and use one of a specified length.

However, it has been difficult to employ conventionally known connection methods (brazing, pressure welding, welding, etc.) because the electrical resistance of the connection part is high and the amount of heat generated when electricity is applied increases. In order to improve this problem, there is a method of connecting superconducting wires as proposed in Japanese Patent Laid-Open No. 16207/1983.

As shown in FIG. 11, this connection method involves removing the stabilizing material from the connecting portions of the superconducting wires 1 and 1a to be connected, and connecting the exposed superconducting filaments 2 and 2a by stacking them on top of each other. The superconductor filaments 2 and 2a are housed in a pipe 3 and crimped together through the pipe 3, thereby crimping and joining the housed superconductor filaments 2 and 2a to each other. In the same figure, 4
is the soldering part.

However, in this joining method, the superconducting filaments 2, 2a of the superconducting wires 1 and 1a that are to be connected to each other contact only the overlapping portions of their outer surfaces, making it difficult to ensure a high critical current value. Also, the superconducting filament 2 on the contact side
and 2a are bent inside the superconducting wires 1, 1a and subjected to plastic working when crimped through the pipe 3, and as a result, they are prone to breakage and have the disadvantage of deteriorating their superconducting properties.

Further, as shown in FIG. 9, after crossing the superconducting filament 2, 2a at the tips of the superconducting wires 1, 1a to be joined with the superconducting wires 1, 1a facing each other, a pipe 3 is inserted. It has been proposed to bond by crimping.

However, with this connection method, the roots of the superconducting filaments 2, 2a cannot be tightly crimped, so the superconducting filaments 2, 2a tend to oscillate in high magnetic fields, making it impossible to secure a high critical current value. Nakatsuta.

For this reason, as shown in Fig. 10, a method of crimping and joining the bases of the superconducting filaments 2, 2a with a pipe 3 via sleeves 5, 5a has been considered, in order to ensure a high critical current value. It became.

However, even with this joining method, the gap between the superconducting filaments 2, 2a and the sleeves 5, 5a could not be sufficiently eliminated, and sufficient adhesion could not be obtained.

[Problem that the invention seeks to solve]

The above-mentioned conventional technology does not take into account the degree of adhesion and disconnection of the superconducting filaments when they cross, and there is a problem in that it is difficult to stably obtain a high critical current value.

The present invention has been made in view of the above points,
The object of the present invention is to provide a method for joining superconducting wires, which makes it possible to obtain a connection joint with high adhesion of superconducting filaments, no disconnection, and a stable critical current value.

[Means for solving problems]

The above purpose is to remove the stabilizing material at the joint end of the superconducting wire with a release agent, form a convex protrusion at the joint end of the superconducting wire from which the stabilizing material has been removed, and then remove the stabilizing material. After arranging the superconducting filaments of the superconducting wire to face each other, overlapping the opposed superconducting filaments so as to cross each other, and crossing each other so as to cover the ends of the opposing superconducting wires,
This is achieved by crimping the intersections of these crossed superconductor filaments with pipes.

[Effect]

Since the above means is provided, the superconductor filaments come into good contact with each other, and a high degree of adhesion can be obtained. In addition, during crimping, the root of the superconducting filament is not only covered and protected by the opposing superconducting filament, but also the plastic working becomes gentle, there is no disconnection from the root, and a stable critical current value can be ensured. .

〔Example〕

The present invention will be explained below based on the illustrated embodiments. An embodiment of the present invention is shown in FIGS. 1-8. Note that parts that are the same as those in the prior art are designated by the same reference numerals, and therefore their explanations will be omitted. In this example, after removing the stabilizing material at the joint ends of the superconducting wires 1a, 1 with a release agent and forming a convex protrusion at the joint ends of the superconducting wires 1a, 1 from which the stabilizing material was removed, The superconducting filaments 2, 2a of the superconducting wires 1a, 1 from which the stabilizing material has been removed are made to face each other, and the opposed superconducting filaments 2, 2a are superimposed so as to intersect, and the opposing superconducting wires 1a, 1 The intersection of the crossed superconductor filaments 2 and 2a is inserted into the pipe 3.
I crimped it with By doing this, the superconducting filaments 2, 2a come into good contact with each other, and the root portions of the superconducting filaments 2, 2a are not only protected by the opposing superconducting filaments 2, 2a, but also the plastic working becomes gentle. Therefore, it is possible to obtain a method for joining superconducting wires that makes it possible to obtain a connection joint in which the superconductor filaments 2 and 2a have a high degree of adhesion, and has no disconnection and a stable critical current value.

That is, as shown in FIG. 4, the stabilizing material is removed from the tips of the superconducting wires 1 and 1a to be joined using a stripping agent such as concentrated nitric acid to expose the superconducting filaments 2 and 2a. Next, superconducting wire 1
After forming a convex protrusion at the joint end of a, 1,
As shown in FIGS. 5 to 7, the superconductor filaments 2 and 2a are expanded to create a space in the center, and as shown in FIG. 8, the superconductor filaments 2 are placed facing each other. The superconducting filaments 2 and 2a are crossed by covering the end of the superconducting wire 1a and covering the opposing end of the superconducting wire 1 with the superconducting filament 2a. Next, as shown in FIG. 1, a copper pipe 3 is placed over the intersection and crimped. In this case, the ends of the pipe 3 are brought into contact with the superconducting wires 1 and 1a during crimping. That is, the opposing superconducting wires 1, 1 cross over the ends of the superconducting filaments 2, 2a that cross the pipe 3.
The size was set to span a.

By doing this, the superconducting filaments 2 and 2a come into good contact with each other (see Figure 2),
The root portions of the superconductor filaments 2, 2a are protected by the opposing superconductor filaments 2a, 2 (see FIG. 3). Therefore, there is no disconnection at the base of the superconductor filaments 2, 2a during crimping with the pipe 3, and the superconductor filaments 2, 2a are not disconnected.
A high degree of adhesion of 2a can be obtained. In addition, the pipe 3 is made longer than the intersecting superconducting filaments 2, 2a so that the pipe 3 and the superconducting wires 1, 1a come into contact with each other during crimping. As a result, when the superconductor filaments 2, 2a are quenched, the pipe 3 separates the flow and acts as a stabilizing material. In addition, in this embodiment, the joining end side 6 of the superconducting wires 1 and 1a
Since a convex protrusion is formed in the superconductor filaments 2 and 2a, the plastic working at the base portions of the superconductor filaments 2 and 2a is gradual during crimping with the pipe 3, and a stable critical current value can be ensured.

Regarding the case where a convex protrusion is not provided at the joint end, the case where it is carried out in the same manner as in the case of this embodiment is considered as a type, and its effects are compared to the conventional type (see Fig. 9) and the type (see Fig. 10). ) and the critical current value. As shown in Fig. 12, the result is that the critical current value of the type corresponding to this example is larger than that of the conventional type, and is on the same level as the guaranteed value of a superconducting wire without a joint. However, it goes without saying that when a convex protrusion is provided at the joint end of this embodiment, a more stable critical current value can be secured than in the case of the type.

〔Effect of the invention〕

As described above, in the present invention, the superconducting filaments are in good contact with each other, and during crimping, the base of the superconducting filament is not only covered and protected by the opposing superconducting filament, but also the plastic working is gradual, and the superconducting filament is It is possible to obtain a method for joining superconducting wires that makes it possible to obtain a connection joint that has high adhesion between body filaments, is free from disconnection, and has a stable critical current value.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional side view showing the crossing state of superconducting filaments during bonding in an embodiment of the superconducting wire bonding method of the present invention, and FIG. 2 is a cross-sectional view of FIG. 1 after crimping.
A cross-sectional view along line A, Figure 3 is B in Figure 1 after crimping.
-A cross-sectional view taken along line B, FIG. 4 is a vertical cross-sectional side view showing the state in which the stabilizing material at the joint end of the superconducting wire of one embodiment has been removed, and FIG. A vertical side view showing a state in which a space is provided in the filament, FIGS. 6 and 7 are cross-sectional views taken along the line C-C in FIG. 5, and FIG. FIG. 9 is a vertical side view showing the intersecting state of superconductor filaments during bonding using a conventional method for bonding superconducting wires, and FIG. FIG. 11 is a vertical side view showing the crossing state of the superconducting filaments in another example of the conventional joining method of superconducting wires, and FIG. FIG. 2 is a characteristic diagram of critical current values of a superconducting wire according to an embodiment of the superconducting wire joining method and a superconducting wire according to a conventional example. 1, 1a... superconducting wire, 2, 2a... superconducting filament, 3... pipe, 5... joining end side of superconducting wire.

Claims (1)

[Scope of Claims] 1. After removing the stabilizing material at the joint end of the superconducting wire with a release material and forming a convex protrusion at the joint end of the superconducting wire from which the stabilizing material has been removed, The superconducting filaments of the superconducting wire from which the oxidizing material has been removed are made to face each other, and the opposed superconducting filaments are overlapped so as to cross each other, and the ends of the opposing superconducting wires are covered with each other. A method for joining superconducting wires, characterized in that the intersections of crossed superconducting filaments are crimped with a pipe. 2. The method of joining superconducting wires according to claim 1, wherein the superconducting filaments are crossed with a space provided at the center thereof. 3. The method of joining superconducting wires according to claim 1, wherein the pipe is sized to span between the opposing superconducting wires and is formed so as to come into contact with the superconducting wires during the crimping.