JPH076699B2 - Cryogenic device - Google Patents

Description

The present invention relates to a cryogenic device, and more particularly to a cryogenic device for holding a container containing a superconducting magnet and the like at a cryogenic temperature.

(Prior Art) In recent years, a cryogenic device applied to a superconducting magnet or the like and using helium as a cooling medium is being used.

Such a cryogenic device is a container in which a superconducting magnet is immersed in liquid helium, is housed in a vacuum container, and the superconducting magnet is kept at a cryogenic temperature with liquid helium, and the vacuum container is placed in a vacuum state. It is designed to prevent heat input from the outside.

And, conventionally, radiation shields are multiply provided on the outside of the container so that each of these radiation shields can be cooled by a refrigerator, or helium vapor can be recondensed to reduce evaporation loss of helium. Alternatively, it is set to 0.

(Problems to be solved by the invention) In such a device, helium is used as a refrigerant because it is hard to solidify at an extremely low temperature, but a gas other than helium is mixed as an impurity in the circulation pipe of this refrigerant. The impurities may be solidified inside the device. Therefore, many failures occur such as blocking the piping.

The impurities include air (oxygen, nitrogen, etc.), water, vapor of lubricating oil, etc., and it is difficult to completely prevent these impurities from being mixed.

Therefore, if a failure occurs, the
The helium liquid evaporates immediately, rendering the device unusable.

The present invention has been made in view of the above points, and an object thereof is to provide a cryogenic device that can be continuously used by minimizing evaporation of the liquid refrigerant even when a part of the refrigerator breaks down. To do.

[Structure of Invention]

(Means for Solving the Problems) In order to achieve the above object, the cryogenic device according to the present invention is a cooling device for cooling a radiation shield, which cools a radiation shield provided outside a container in which a cryogenic liquid is contained. And a cryogenic device having a vapor recondensing refrigerator for cooling and recondensing the vapor of the cryogenic liquid, a precooling refrigerator for precooling the vapor recondensing refrigerator is radiated via a heat switch. The precooling refrigerator and the radiation shield cooling refrigerator are connected to the shield, and the main parts have the same standard and are compatible with each other.

(Operation) The present invention can repair the radiation shield cooling refrigerator by stopping the precooling refrigerator and diverting its parts when the radiation shield cooling refrigerator, which is a problem, fails. .

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

Liquid helium 2 as a cryogenic refrigerant is placed inside the container 1.
And the super-electric coil 3 is immersed in the liquid helium 2. In the present embodiment, radiation shields 4 and 5 are doubly provided outside the container 1, and the container 1 and the radiation shields 4 and 5 are housed in a vacuum container 6. Further, for example, a GM refrigerator (Gifode McMahon cycle refrigerator) 7 is attached to each of the radiation shields 4 and 5.
Are connected via thermal switches 8a and 8b, respectively, to cool the radiation shields 4 and 5 to a predetermined temperature.
Further, a condensing heat exchanger 10 of a JT loop (Joule-Thomson loop) 9 is arranged inside the container 1, and the JT loop 9 is precooled by a precooling GM refrigerator 11. Further, the GM refrigerator 11 for pre-cooling is similar to the GM refrigerator 7 in that the radiation shields are provided via the heat switches 8c and 8d.
It is connected to 4 and 5, and the GM refrigerator 7 and the GM for pre-cooling.
The refrigerator 11 has the same major parts as each other,
It is designed to be compatible.

In this embodiment, the liquid helium 2 in the container 1 cools the superconducting coil 3 to an extremely low temperature.
In order to prevent the invasion of radiant heat from the outside, the heat input by blocking the conduction and convection of gas such as air by covering it with a vacuum container 6 and cooling the radiation shields 4 and 5 by the GM refrigerator 7. Is reduced. Further, when the liquid helium 2 in the container 1 is evaporated, it is re-condensed by the condensation heat exchanger 10 of the JT loop 9 and the apparent evaporation amount is made zero.

When a failure occurs in the refrigerator system, the following measures are taken.

First, when the pre-cooling GM refrigerator 11 fails, the pre-cooling GM refrigerator 11 may be stopped and the temperature of only the pre-cooling GM refrigerator 11 may be repaired. The GM refrigerator 7 and the JT loop 9 are in operation. There is almost no evaporation of liquid helium 2. Further, when a failure such as clogging of the JT loop 9 occurs, the JT valve 12 may be closed to raise the temperature of the condensation heat exchanger 10 for cleaning,
Since the evaporation of the liquid helium 2 is suppressed to a low level by the GM refrigerator 7, the super-electric coil 3 can be continuously used if the storage amount of the liquid helium 2 is allowed.

Further, if the GM refrigerator 7 fails, the temperature of the radiation shields 4 and 5 will rise rapidly unless repair is performed immediately. For example, if the temperature of the outer radiation shield 5 is 20 ° K to 40 ° K or 60 ° C. When the temperature rises to ° K, the heat input due to radiation becomes 8 to 80 times. Therefore, when repairing in this embodiment, the heat switches 8a and 8b are turned off, the heat switches 8c and 8d of the pre-cooling GM refrigerator 11 are turned on, and the radiation shields 4 and 5 are cooled by the pre-cooling GM refrigerator 11. While doing so, only the GM refrigerator 7 is heated to replace the defective part. At this time, two GM refrigerators 7,11
The number of spare parts is smaller than in the case of two types of refrigerators, and the types of parts can be increased. Therefore, the spare parts can be enhanced, and quick repairs can be performed, and when the spare parts are not in time, the pre-cooling GM refrigerator 11 can be stopped and the parts can be reused.

Therefore, even if the GM refrigerator 7 breaks down, it can be repaired immediately, and rapid evaporation of liquid helium does not occur, so that the continuous use of the superconducting coil 3 can be ensured.

The cryogenic liquid refrigerant is not limited to liquid helium, and any refrigerant may be used.

〔The invention's effect〕

As described above, the cryogenic device according to the present invention is designed so that the radiation shield cooling refrigerator and the precooling refrigerator are compatible with each other as main components having the same standard. In such a case, repair can be performed quickly and the number of spare parts can be reduced. Further, since quick repair can be performed, evaporation of the liquid refrigerant can be suppressed to a minimum, and the device can be continuously used.

BRIEF DESCRIPTION OF THE DRAWINGS The drawings are schematic configuration diagrams showing an embodiment of a cryogenic device according to the present invention. 1 ... Container, 2 ... Liquid helium, 3 ... Superconducting coil, 4,5
… Radiation shield, 7,11… GM refrigerator, 9… JT loop.

Claims (1)

[Claims] 1. A radiation shield cooling cooler for cooling a radiation shield, which is provided outside a container containing a cryogenic liquid therein, and a vapor recondensing refrigerator for cooling and recondensing the vapor of the cryogenic liquid. In a cryogenic device having, a precooling refrigerator for precooling the vapor recondensing refrigerator is connected to a radiation shield via a heat switch, and the precooling refrigerator and the radiation shield cooling refrigerator are Cryogenic device with main parts having the same standard and compatible structure.