JPS60170908A - Superconductive magnet - Google Patents

Abstract

PURPOSE:To prevent deterioration of critical current of superconductive wire, on the occasion of exposing an conductor to two kinds of ambients when it is placed through the partitioning wall, by using a superconductive wire as a conductor provided therethrough and hermetically sealing the area through which the superconductor is placed with the brazing at a temperature as low as 400 deg.C or less. CONSTITUTION:A conductor 12 consisting of superconductive wire is placed through a partitioning wall 5 and is exposed to different ambients 3 and 4 through the wall 5. In this case, the passing area is hermetically sealed by a low temperature brazing at a temperature of 400 deg.C or less. In this case, an alloy mainly consisting of tin and lead is used as the brazing material and a superconductive magnet having the conductor passing area which prevents critical current of superconductive wire and has no resistance loss can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a superconducting magnet, and in particular, to a superconducting magnet having a conductor that penetrates the atmosphere.

[Prior art]

Conventionally, there has been a device of this type as shown in FIG.

In the figure, the superconductors @'a+/b are electrically connected to each other by the through conductors, and the through conductors separate the atmospheres 3 and 3 so that the superconducting wires ia and ib are in different atmospheres 3 and 3, respectively. The partition spike S is hermetically sealed and penetrated. The superconducting wire 1 is cooled to an extremely low temperature of 10 K (-2'43° C.) or lower by the atmosphere 3 or silica, and is maintained in a superconducting state with an electrical resistance of O.

The through conductor C and the partition wall S are welded or 1. ．． They are joined by high-temperature brazing at a temperature of 00 to 7000°C, and a hermetic seal is maintained.

On the other hand, what about alloy superconducting wire? Since the superconducting critical current deteriorates due to the application of a temperature of about 0.000° C., a normal conductive material having electrical resistance has been used for the through conductor 2 to be joined by welding or high temperature brazing as described above.

The above configuration is a coil terminal of a forced cooling type superconducting magnet cooled by liquid helium or supercritical helium,
It is used for coil terminals of superconducting magnets cooled by superfluid helium, and helium, vacuum, etc. are applicable as the ash surrounding.

- However, in conventional devices equipped with coil terminals configured as described above, a normal conductive material was used for the through conductor A that penetrates between the two atmospheres, so the through conductor A and the through conductor A are superconducting. There was a drawback that resistance heat generation occurred at the connecting portion of the lines /a and /b.

[Summary of the invention]

The purpose of this invention is to eliminate the drawbacks of the conventional ones as described above, and it uses a superconducting wire as the through conductor, and hermetically seals the through conductor and the partition wall by low-temperature brazing at a temperature below qoo degrees Celsius. By doing so, critical current deterioration of the superconducting wire is prevented, and a superconducting magnet having a conductor penetration portion without resistance loss is provided.

[Embodiments of the invention]

Hereinafter, one embodiment of the invention will be described with reference to the drawings. In FIG. 2, a through conductor 12 made of a superconducting wire is placed in an atmosphere 3.
．． Atmosphere 3. The partition wall S is brazed to the partition wall S so that the q does not flow with each other. The brazing of the through conductor 12 and the partition wall S is carried out at 100°C to prevent critical current deterioration in the superconducting wire.
The following low-temperature brazing is used.

The use of such low-temperature brazing for cryogenic seals has traditionally been considered difficult in terms of reliability, but by appropriately selecting superconducting wire sheathing materials, partition wall materials, low-temperature brazing materials, etc. , a highly reliable conductor penetration part can be obtained.

Further, a prototype example according to the present invention will be explained below. In Fig. 3, a through conductor 7.2 made of superconducting wire is shown.
and the partition wall S are joined by low-temperature brazing filler metal. Table 1 shows test results for prototypes with different types of brazing filler metal.

Atmosphere leakage occurred in Sample I using brazing filler metal A, but no leakage occurred in Sample L using appropriately selected brazing filler metal B even at room temperature and after heat cycles. Filter here / (Note 1) In the normal temperature leak test, the joint between the shell gas interrogator and the partition wall S is inspected at 20°C using a helium leak detector.
A leak of less than X/0' Torr-A/s was determined to be no leak.

(Note 2) For the leakage test after heat cycle, a leak test was conducted at 20°C in the same manner as in (Note 1) on a sample that was rapidly cooled from 20°C to -269°C and then rapidly heated 10 times.

(Note 3) For the strength test after heat cycle, the brazing part strength of the sample used in (Note 1) was determined as a pull-out load of 1 for the through conductor/2.

In addition, in the above embodiment, the through-conductor partition wall has the shape shown in the figure, but other shapes may be used, and the through-conductor,
The partition wall, the atmosphere, the low-temperature brazing material, etc. are not limited to specific materials.

〔Effect of the invention〕

As described above, the present invention uses a superconducting wire as a penetrating conductor that penetrates two types of atmospheres, and closes the tightly punctured seal portion to tI.
By joining by low-temperature brazing at 0° C. or lower, a superconducting magnet having a conductor penetration portion without resistance loss can be obtained.

[Brief explanation of drawings]

FIG. 1 is a side sectional view showing a conductor penetration part of a conventional device, FIG. 2 is a side sectional view of a main part of an embodiment of the present invention, and FIG. 3 is a side sectional view of a main part showing a prototype example of the present invention. Figure 7 is the IV of Figure 3.
- It is a sectional view in the plane overflowing to the IV line. 3. Da...atmosphere, left...partition wall, 7.2...penetrating conductor. In each figure, the same reference numerals indicate the same or equivalent number. Money 1 Figure 2 Grass 2 Figure Leather 3 Figure Flame 4 Figure

Claims (1)

[Claims] In a superconducting magnet equipped with a coil end portion having a penetrating conductor that is hermetically sealed and penetrates a partition wall that partitions a German atmosphere, the hermetic seal is applied by low-temperature brazing at a temperature below yoo°C, and the coil is made of superconducting wire. A superconducting magnet characterized by comprising a through conductor.