JPH0869719A - Current lead for superconducting device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a current lead for a superconducting device in which a high temperature superconductor is not damaged by a difference in thermal contraction. [Structure] A coil spring-like flexible body in which a superconducting wire made of a superconductor containing a single wire or a plurality of stabilizing materials such as copper or aluminum connected to a superconducting device in a cryogenic container is spirally wound. A low temperature side lead made of a high temperature superconductor connected to the flexible body and showing a superconducting state at a temperature of liquid nitrogen or higher, and a room temperature side lead connected to the low temperature side lead.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a superconducting coil immersed in liquid helium contained in a liquid helium container,
The present invention relates to improvement of a current lead for supplying a current from a power supply placed in a room temperature environment.

[0002]

2. Description of the Related Art A current lead is used as a means for supplying a current from an exciting power supply placed in a room temperature environment to a superconducting coil that is immersed in liquid helium and cooled in a liquid helium container. . In superconducting devices, very expensive liquid helium evaporates due to heat conduction from the outside, radiation, and heat penetrating from the current leads. Among them, in a normal superconducting device, heat infiltrated from a current lead occupies most of the whole.

Therefore, it has been considered to form a current lead by using a high-temperature superconductor that exhibits a superconducting state at a temperature of liquid nitrogen or higher to reduce the heat of penetration (Japanese Patent Laid-Open No. 63-292610). The high temperature end of the high temperature superconductor is cooled to around 80 K with liquid nitrogen contained in a liquid nitrogen container and brought into a superconducting state. Since the high-temperature superconductor has a low thermal conductivity, the heat entering the liquid helium container is small, and the electric resistance is zero, so that Joule heat generation due to energization does not occur. Therefore, the current lead using the high temperature superconductor can be expected to have a great effect on reducing the evaporation amount of liquid helium.

[0004]

Since the high-temperature superconductor is a ceramic system, a difference in thermal contraction occurs between the liquid helium container made of stainless steel or the like, the liquid nitrogen container, the gas pipe, and the lead made of copper or the like, which constitutes the superconducting device. Since the ceramic high-temperature superconductor is mechanically brittle, there is a possibility that it will be damaged due to the difference in thermal contraction and it will not be possible to energize. An object of the present invention is to provide a current lead for a superconducting device in which a high temperature superconductor is not damaged by a difference in thermal contraction.

[0005]

To achieve the above object, the current lead of the present invention is a superconductor containing a stabilizing material such as a single wire or a plurality of copper or aluminum connected to a superconducting device in a cryogenic container. A coil spring-like flexible body formed by spirally winding a superconducting wire consisting of, a low temperature side lead consisting of a high temperature superconductor showing a superconducting state above the liquid nitrogen temperature connected to this flexible body, and a low temperature side lead The structure is provided with a connected room temperature side lead.

Further, the flexible body is formed by assembling a plurality of superconducting wires made of a superconductor containing a stabilizing material such as copper or aluminum into a flat braided wire or twisting a plurality of superconducting wires.

[0007]

In such a current lead for a superconducting device, the flexible body made of the superconducting wire absorbs the difference in heat shrinkage caused by cooling. Moreover, since the flexible body is in a superconducting state, it does not generate Joule heat.

[0008]

【Example】

(Structure of Embodiment) An embodiment of the present invention will be described below with reference to FIG. In FIG. 1, reference numeral 1 denotes a superconducting coil formed by winding a superconducting wire. The superconducting coil 1 is immersed in liquid helium 3 contained in a liquid helium container 2 made of stainless steel or the like. Also, this liquid helium container 2
Are housed in an adiabatic vacuum container 4 made of stainless steel or the like. Reference numeral 5 is a coil spring flexible body formed by spirally winding a superconducting wire made of a superconductor containing a stabilizing material such as copper or aluminum. It is connected to the low temperature side lead 7 made of a ceramic type high temperature superconductor which shows the state. A normal temperature side lead 8 made of a copper rod has a low temperature end penetrating a liquid nitrogen container 10 containing liquid nitrogen 9 and connected to a high temperature end of a low temperature side lead 7, and a normal temperature terminal 11 is provided at the high temperature end. The room temperature terminal 11 is connected to an exciting power source which is not shown in the drawing and is operated under a room temperature environment. Reference numeral 12 is a gas flow pipe made of stainless steel or the like provided on the outer periphery of the low temperature side lead 7,
It serves as a flow path for the helium gas 13 vaporized in the liquid helium container 2.

FIG. 2 is a diagram showing details of a connecting portion of the coil spring flexible body 5, the superconducting coil terminal 6 and the low temperature side lead 7. 5a is a flexible low temperature side connector made of copper, 5b
Is a flexible high temperature side connector made of copper. Each is connected by soldering.

(Operation of Embodiment) The difference in thermal contraction caused by cooling that occurs in the liquid helium container 2 made of stainless steel or the like, the liquid nitrogen container 10, the gas passage tube 12, the normal temperature side lead 8 and the low temperature side lead 7 can be a coil spring. Since the flexible body 5 has a coil spring shape, it is absorbed. The coil spring flexible body 5
Is a superconducting wire and is in a superconducting state, so there is no Joule heat generation.

(Effects of Embodiment) Therefore, the low-temperature side lead made of a high-temperature superconductor which is mechanically brittle due to the difference in thermal contraction is not damaged and current cannot be passed.

(Other Embodiments) FIG. 3 is a view showing a main part of a current lead according to another embodiment of the present invention. Reference numeral 14 denotes a flat knit flexible body in which superconducting wires made of a superconductor containing a plurality of stabilizing materials such as copper or aluminum are assembled in a flat knit shape.

FIG. 4 is a view showing a main part of a current lead according to another embodiment of the present invention. Reference numeral 15 is a flexible stranded wire formed by twisting a superconducting wire made of a superconductor containing a plurality of stabilizing materials such as copper or aluminum. Both the flat knit flexible body 14 and the stranded wire flexible body 15 absorb the difference in heat shrinkage due to cooling and do not generate Joule heat.

[0014]

As described above, according to the present invention, a coil spring flexible body in which a single wire or a plurality of superconducting wires are spirally wound between a superconducting device in a cryogenic container and a low temperature side lead made of a high temperature superconductor. Since it is connected, the difference in heat shrinkage caused by cooling can be absorbed, and the low temperature side lead is not damaged. Moreover, since the coil spring flexible body is in a superconducting state, Joule heat is not generated and the evaporation amount of liquid helium does not increase. Further, the same effect can be obtained by superposing the superconducting wires into a flat knitted shape or using a twisted wire.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a current lead for a superconducting device according to an embodiment of the present invention.

FIG. 2 is a detailed view showing a main part of FIG.

FIG. 3 is a detailed view corresponding to claim 3;

FIG. 4 is a detailed view corresponding to claim 4.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Superconducting coil 2 ... Liquid helium container 3 ... Liquid helium 4 ... Adiabatic vacuum container 5 ... Coil spring flexible body 5a ... Flexible body low temperature side connector 5b ... Flexible body high temperature side connector 6 ... Superconducting coil terminal 7 ... Low temperature side lead 8 ... Room temperature side lead 9 ... Liquid nitrogen 10 ... Liquid nitrogen container 11 ... Room temperature terminal 12 ... Gas flow pipe 13 ... Helium gas 14 ... Flat knit flexible body 15 ... Stranded flexible body

Claims (4)

[Claims] 1. A current lead for a superconducting device which supplies a current to a superconducting device housed in a cryogenic container from a power source placed in a room temperature environment, the flexible body comprising a superconducting wire connected to the superconducting device. And a low temperature side lead made of a high temperature superconductor connected to the flexible body and exhibiting a superconducting state at a temperature of liquid nitrogen or higher, and a room temperature side lead connected to the low temperature side lead. Current lead for superconducting device. 2. The current lead for a superconducting device according to claim 1, wherein a single wire or a plurality of superconducting wires are spirally wound to form a coil spring-like flexible body. 3. The current lead for a superconducting device according to claim 1, wherein the plurality of superconducting wires are made of a knitted flat braided flexible body. 4. The current lead for a superconducting device according to claim 1, wherein a plurality of superconducting wires are twisted to form a flexible body.