JPH04343208A - Connecting method for superconducting coil - Google Patents

Abstract

PURPOSE:To prevent deterioration of cooling efficiency by conducting a coil-to- coil connection completely in forced-cooling type superconducting coils having the structure in which a superconducting lead wire is surrounded by sheathing material. CONSTITUTION:A terminal tube 3A, with a connecting flange 4A, is provided on one end of a first superconducting coil, one end of afotesaid terminal tube 3A is connected to the sheathing material 2A of the superconducting coil, the other end of the terminal tube 3A is connected to the superconducting wire 1A of the superconducting coil wire, and then the superconducting wire 1A of the first superconducting coil is connected to the superconducting wire 1B of the second superconducting coil. A terminal tube 3B, with a connection flange 4B, is provided in such a manner that the above-mentioned connected parts are enclosed, one end of the terminal tube 3B and the other end of the terminal tube 3A are connected, and the other end of the terminal tube 3B and the sheathing material 2B of the second superconducting coil are connected.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connection method applied to forced cooling type superconducting coils in power storage, nuclear fusion reactors, particle accelerators, and the like.

0002

2. Description of the Related Art A forced cooling type superconducting coil has a structure in which a superconducting wire is surrounded by a sheath material. Conventionally, when connecting such superconducting coils, a method as shown in FIG. 4 has been adopted.

That is, one connecting tube 8 is arranged around the connecting portion of the superconducting wires 1A and 1B, and the sheath material 2A of the superconducting wire 1A and the sheath material 2B of the superconducting wire 1B on both sides are soldered. At the same time, a connecting block 9 is placed in the connecting tube 8, and the connecting block 9 and the superconducting wire 1 are connected by bonding or welding.
Airtightness was achieved by soldering the three parts A, 1B and the connecting tube 8.

0004

[Problems to be Solved by the Invention] In the conventional method as described above, as shown in FIG.
B is separated by the connection block 9 and the soldering part 7.
E, 7F. Since these are buried in the connecting tube 8, it is impossible to visually observe whether they are good or bad during soldering work. Therefore, if a defect occurs in the soldered portion 7E or 7F, there is a problem in that the liquid He 2 from 6A and 6B gets mixed together in the connecting pipe, resulting in poor cooling performance.

[0005] That is, liquid He liquefied in a refrigerator
The inlet temperature to the coil is extremely low, around 4.2 K, but the outlet temperature after flowing along the several hundred meter long coil is several K higher. When this mixes with the liquid He on the inlet side, the inlet temperature rises, and eventually the temperature of the entire coil rises as the process is repeated. The critical temperature of a superconducting wire is 9.2k for NbTi, which is the most commonly used material, so there is only a 5k margin of temperature margin, and if the temperature rises any higher, it will no longer be superconducting, causing the so-called quetin phenomenon. In such a forced cooling type superconducting coil, mixing of liquid He on the inlet side and the outlet side is a fatal problem.

[0006]Also, as shown in Fig. 5, it is possible to divide the connecting pipe into two end pipes 3A and 3B and keep each end of the coil separate.
There remains a portion that is not directly cooled by e, and as a result, a problem arises in the cooling performance as described above.

The present invention has been made in view of the above points, and in a forced cooling type superconducting coil in which a superconducting wire is surrounded by a sheath material, the coils are completely connected to each other, and cooling is achieved. An object of the present invention is to provide a method for connecting superconducting coils that can prevent performance deterioration.

[0008]

[Means for Solving the Problems] The present invention solves this problem by providing a double structure for the connecting tube at the connecting portion of the forced cooling type superconducting coil. That is, as shown in FIG. 1, an end tube 3A (first end tube) with a connecting flange 4A is provided at one end of the first superconducting coil, and one end of this end tube 3A is connected to the first superconducting coil. The other end of the sheath material 2A and the end tube 3A and the superconducting wire 1A of the first superconducting coil are connected to each other by soldering, for example, to maintain airtightness. Next, the first
For example, after overlapping and soldering the superconducting wire 1A of the superconducting coil and the superconducting wire 1B of the second superconducting coil,
An end pipe 3B (first end pipe) with a connecting flange 4B is provided surrounding this soldering part 7C, and one end of this end pipe 3B, the other end of the end pipe 3A, and the other end of the end pipe 3B are connected to each other. The sheath material 2B of the second superconducting coil is soldered, for example, at portions 7D and 7E to ensure airtightness.

[0009]

[Operation] According to the above connection method, the connecting pipe has a double structure, and the connection can be made while ensuring the airtightness of the liquid He. That is, in the connection process, first, as shown in FIG. 2, after soldering the end tube 3A, sheath material 2A, and superconducting wire 1A at locations 7A and 7B, respectively, the airtightness of these soldered portions 7A and 7B is determined. It is possible to inspect. If it passes this inspection process, it will proceed to the next process, and if it fails, it can be re-soldered and re-inspected.

As the second step after passing the inspection, the process shown in FIG.
After passing the end tube 3B through the sheath material 2B as shown in FIG. 2, it is possible to solder the superconducting wire 1A and the superconducting wire 1B at a location 7C, and then test the electrical resistance of the connection. Similarly,
If it passes this inspection, it will proceed to the next step, and if it fails, it can be re-soldered and re-inspected.

Next, as a third step, as shown in FIG. 1, the end tube 3B is set in a predetermined position, soldered at 7D and 7E, and an airtight test is performed. If it passes this final airtightness inspection, it is complete.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method of connecting forced cooling type superconducting coils according to an embodiment of the present invention will be described below with reference to the drawings.

An embodiment of the present invention is shown in FIG. In Figure 1,
This figure shows the structure of a superconducting coil connecting portion 5 in which superconducting wires 1A and 1B are surrounded by sheath materials 2A and 2B, respectively. There is a gap between the superconducting wire 1A and the sheath material 2A,
The superconducting wire 1A is cooled to an extremely low temperature by flowing liquid He into this gap. The same applies between the superconducting wire 1B and the sheath material 2B. This joint requires electrical connection and airtightness against the liquid He.
It is important that streams 6A and 6B of e do not mix. Therefore, in this embodiment, the joint part has a double structure, and the end tubes 3A and 3B of different sizes are used to connect the superconducting wires 1A and 1B.
It has a structure that surrounds it, and each joint is joined by soldering.

[0014] In order to realize this structure, first, the first
In the process, as shown in FIG. 2, an end tube 3A with a connecting flange 4A is attached to one end of the first superconducting coil, and one end of this end tube 3A is connected to the sheath material 2A, and the other end of the end tube 3A is connected to the superconducting coil. Connect it to the conductive wire 1A by soldering. Pb-Sn type solder is generally used, but other solders include Pb-Ag type, Pb-In type, In-Sn type, and B
i-Sn type etc. can also be used. After soldering in this way, attach the blind cover to the connection flange 4A, and then
Pressurize with gas and inspect the airtightness of the soldered parts 7A and 7B.

Next, as a second step, as shown in FIG. 3, after passing the end tube 3B with the connecting flange 4B through one end of the second superconducting coil, the first and second superconducting coils are connected to each other. The respective superconducting wires 1A and 1B are overlapped and soldered.

Next, as a third step, as shown in FIG. 1, one end of the end tube 3B is overlapped with the other end of the end tube 3A, and the gap 7D is
And the gap 7E with the sheath material 2B is joined by soldering. After joining, the airtightness of the soldered parts 7D and 7E is inspected by pressurizing them from the inside with He 2 gas. If this test passes, place the entire coil in a vacuum container and connect the connecting flange A.
After flowing liquid He from B and cooling the superconducting wire to 4.2k, a conduction test is performed. This maintains a superconducting state with zero electrical resistance, and confirms that the coil, including its connections, is healthy.

[0017]

[Effects of the Invention] As described above, according to the present invention, in a forced cooling type superconducting coil in which a superconducting wire is surrounded by a sheath material, the connecting tube has a double structure, so that the coils can be connected to each other. Connections can be made soundly, thereby preventing deterioration in cooling performance.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a connecting portion according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the connection portion of the same embodiment in a first step.

FIG. 3 is a cross-sectional view of the connection portion of the same embodiment in a second step.

FIG. 4 is a sectional view of a conventional connection section.

FIG. 5 is a sectional view of a conventional connection part.

[Explanation of symbols]

1A...Superconducting wire, 1B...Superconducting wire, 2A...Sheath material, 2
B... Sheath material, 3A... End tube, 3B... End tube, 4A... Connection flange, 4B... Connection flange, 5... Superconducting wire connection part,
6A...Flow of liquid He, 6B...Flow of liquid He, 7
A...Soldering part, 7B...Soldering part, 7C...Soldering part, 7D...Soldering part, 7F...Soldering part, 8...Connecting pipe,
9...Connection block.

Claims (1)

[Claims] Claim 1: In a forced cooling type superconducting coil having a structure in which a superconducting wire is surrounded by a sheath material, a first end tube with a connecting flange is provided at one end of the first superconducting coil,
One end of the first end tube and the sheath material of the first superconducting coil, and the other end of the first end tube and the superconducting wire of the first superconducting coil are connected, and then the After connecting the superconducting wire of the first superconducting coil and the superconducting wire of the second superconducting coil, a second end tube with a connecting flange is provided surrounding the connected portion, and the second end tube is provided with a connecting flange to surround the connected portion. A superconducting coil connection characterized in that one end of the end tube is connected to the other end of the first end tube, and the other end of the second end tube is connected to a sheath material of the second superconducting coil. Method.