JP2551875B2 - Superconducting coil cooling device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling device for a superconducting coil, and more particularly to cooling by a regenerator.

[0002]

2. Description of the Related Art Conventionally, it is known that a superconducting substance is formed into a wire and wound to generate a strong magnetic field as the superconducting coil 1. An example of industrial application of this strong magnetic field is the linear motor car. Further, in recent years, the demand for a physical property measuring device for generating a strong magnetic field as a measuring device for measuring the critical magnetic field of a superconducting substance has been increasing.

A cooling method of the superconducting coil 1 used for these is shown in FIG. Liquid helium 5 is supplied from a liquid helium storage container 7 through a transfer tube 6 to an inner container 4 (hereinafter simply referred to as inner container 4) of a vacuum container, and the superconducting coil 1 is immersed in the liquid helium 5 for natural convection. The immersion cooling method used is adopted. Current is supplied to the superconducting coil 1 by a current lead 9. The superconducting coil 1 has a cryostat (adiabatic vacuum container) 2 in order to reduce heat invasion from the room temperature space.
Installed inside. The cryostat is equipped with an inner container 4 of liquid helium 5 of about 4.2K in which the superconducting coil 1 is normally immersed, and a heat shield 3 for suppressing radiant heat from room temperature. The heat shield 3 is cooled by liquid nitrogen or the like although not shown. Liquid Helium 5
Due to the vaporization, the pressure inside the inner container 4 increases, so that the helium gas 8 escapes. Therefore, the supply of liquid helium 5 is indispensable, and it was necessary to supply it periodically during long-term operation. The consumption of expensive liquid helium 5 causes an increase in running cost, and liquid helium 5
It was a big problem in the operation of the system that it required skill to handle.

The conventional example shown in FIG. 4 is a superconducting coil for a physical property measuring apparatus. Further, in consideration of the case where the physical property measuring sample 16 is frequently changed or the liquid physical helium 5 is not desired to be immersed, the regenerator 13 for exclusively cooling the physical property measuring sample 16 and the liquid helium for cooling the superconducting coil 1 are considered. In order to prevent vaporization of 5 as much as possible, a shield cooling refrigerator 17 is provided to cool the heat shield 3. This device is provided with a sample 16 for measuring physical properties from below the superconducting coil 1.
The bottom of the inner container 4, the heat shields 3 and 3, and the vacuum container 2 are recessed in order to take in and out. Then, the regenerator 13 equipped with a physical property measuring device for cooling the physical property measuring sample 16 from below is moved up and down by the manual lifter 25.

[0005]

In the conventional example shown in FIG. 4 as well, the supply of liquid helium 5 is indispensable, and the liquid helium 5 must be handled. Further, a device for immersing the superconducting coil 1 in the liquid 5 to cool it becomes large, and in order to install and operate the shield cooling refrigerator 17 for preventing vaporization of the liquid helium 5, a larger device is required. Cost increased.

[0006]

A superconducting coil (1) is fixed to a cooling stage of a regenerator (13), and a heat shield (3) surrounding the superconducting coil (1) is fixed to another cooling stage. , A current lead (9) connected to the superconducting coil (1) through a vacuum vessel (2) surrounding the heat shield (3).

[0007]

FIG. 1 shows an embodiment of claim 1 of the present invention. The superconducting coil 1 is a coil formed by linearly winding an oxide-based high temperature superconducting substance, and is formed in a cylindrical shape having a through hole in the center. The lower end of the superconducting coil 1 is tightly screwed to the second cooling stage 14 of the regenerator 13. The vacuum container 2 is made of stainless steel and encloses the superconducting coil 1 in a vacuum. The heat shield 3 is made of thin copper in a cup shape,
The superconducting coil 1 is directly included, and the end of the opening is screwed to the first cooling stage 15 in close contact. Current lead 9
Is connected to the superconducting coil 1 to supply a current. The current lead 9 is externally connected to the protective resistor 12, the breaker 11, and the power supply 10. The regenerator 13 has a drive unit that is exposed to the outside of the vacuum container 2 and is connected to the compressor 18 by flexible hoses 19 and 19. Sample 16 for measuring physical properties
Is a superconducting substance, and a strong magnetic field is applied by the superconducting coil 1 to measure the critical magnetic field. Sample 16 for measuring physical properties
Are detachably fixed to the second cooling stage 14.

An embodiment of claim 2 of the present invention is shown in FIG.
This embodiment is an example of using a three-stage refrigerator, and is a device for measuring physical properties in a strong magnetic field. The superconducting coil 1 is screwed and fixed to a third cooling stage 21. The inner container 4 is
Second cooling stage 1 with indium sheet 20 in between
Screw it tightly to 4. The physical property measurement sample 16 is a superconducting substance, and a strong magnetic field is applied by the superconducting coil 1 to measure the critical magnetic field. The physical property measurement sample 16 is detachably fixed to the third cooling stage 21. The heater wire 22 is wound around the lower part of the third cooling stage 21, and the current can be controlled from the outside of the vacuum container 2. The helium introducing pipe 23 is a pipe for introducing the helium gas 8 into the sealed inner container 4. Other structures are similar to those shown in claim 1.

[0009]

[Operation] A few years have passed since the discovery of a high-temperature superconducting material that causes a superconducting phenomenon even at a temperature of about 30K in 1986, and it has become possible to realize a semi-permanently usable superconducting material. Some high-temperature superconducting materials show a superconducting state near liquid nitrogen temperature of 77K. Therefore, it is no longer necessary to cool the liquid to 5 with liquidium or to use a complicated refrigerator or the like to lower the temperature to 4.2K, and to realize a superconducting state even with a simple compact regenerator that lowers it to 20K. Became possible. However, if this 20K refrigerator has a large heat capacity of the object to be cooled,
0K will rise to some extent.

The operation of claim 1 of the present invention will be described with reference to FIG. The inside of the vacuum container 2 is evacuated by a vacuum pump (not shown) to block heat conduction by air. Next, the regenerator 13 is operated to bring the second cooling stage 14 to an extremely low temperature to cool the superconducting coil 1 fixed to it. In addition, the heat shield 3 is cooled by the first cooling stage 15 in order to prevent radiant heat from room temperature. When a current is applied from the current lead 9, a strong magnetic field is generated from the superconducting coil 1.

The operation of claim 2 of the present invention will be described with reference to FIG. After the inside of the vacuum container 2 is evacuated, the inside of the inner container 4 is separately evacuated by the helium introducing pipe 23. Next, the regenerator 13 is operated and sufficiently cooled, and then the helium gas 8 is filled in the inner container 4 through the helium introducing pipe 23. Thereby, heat conduction by the helium gas 8 is performed. Further, although the heater wire 22 is wound around the lower part of the third cooling stage 21, it is possible to set an arbitrary temperature by controlling the current flowing through the heater wire 22. (It is very difficult to take temperatures other than 4.2K with liquid helium 5.)

[0012]

[Effect] The effect of the vacuum container 2 is to prevent heat conduction by air, the effect of the heat shield 3 is to prevent radiant heat, and the superconducting coil 1 can be directly cooled by the regenerator 13. Therefore, the liquid helium 5 becomes unnecessary, the running cost is reduced and the labor for handling the liquid helium 5 is eliminated, and a large device accompanying it is not required, and the size and cost can be reduced. Further, the effect of the second aspect is that the heat conduction of the helium gas 8 in the inner container 4 enables rapid cooling, and the heater wire 22 can set an arbitrary temperature. In addition, the superconducting coil 1 and the sample 16 for measuring physical properties are respectively replaced by helium gas 8
It is also possible to set the temperatures of the superconducting coil 1 and the physical property measurement sample 16 to different temperatures by selecting the area in contact with the third cooling stage 21, the position and size of the heater wire 22, and the like. is there.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of claim 1 of the present invention.

FIG. 2 is a schematic sectional view of claim 2 of the present invention.

FIG. 3 is a schematic sectional view of a conventional example.

FIG. 4 is a schematic sectional view of a conventional example.

[Explanation of symbols]

 1 superconducting coil 2 vacuum container 3 heat shield 4 inner container 5 liquid helium 6 transfer tube 7 liquid helium storage container 8 helium gas 9 current lead 10 power supply 11 circuit breaker 12 protection resistance 13 regenerator 14 second stage cooling stage 15th 1st-stage cooling stage 16 Physical property measurement sample 17 Shield cooling refrigerator 18 Compressor 19 Flexible hose 20 Indium sheet 21 Third stage cooling stage 22 Heater wire 23 Helium introduction pipe 24 Safety valve 25 Manual lifter

Claims (2)

(57) [Claims] 1. A superconducting coil (1) is fixed to a cooling stage of a regenerator (13), and a heat shield (3) surrounding the superconducting coil (1) is fixed to another cooling stage,
A cooling device for a superconducting coil, comprising a current lead (9) connected to the superconducting coil (1) through a vacuum container (2) surrounding the heat shield (3). 2. The superconducting coil (1) according to claim 1.
The inner container (4) of the vacuum container (2) surrounding the container is made airtight, and a helium introducing pipe (23) communicating with the inside of the inner container (4) and the outside of the vacuum container (2) is connected to form a vacuum container (2). A cooling device for a superconducting coil, characterized in that a heater wire (22) is provided therein.