JPS621275B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a superfluid helium cryogenic container that utilizes the heat of vaporization of liquid helium.

Conventionally, liquid helium has generally been used to cool things that generate heat and need to be kept at extremely low temperatures, such as superelectric pulsed magnets, but recently superfluid helium has been used for cooling. Attention has been paid. This superfluid helium (hereinafter abbreviated as He) is normal liquid helium,
In other words, it is made by cooling constant-flow helium (hereinafter abbreviated as He) at about 4.2K to about 2K.
It has very high thermal conductivity.

By the way, a superfluid helium cryogenic vessel (6th International Cryogenic Engineering
Conference1976, P159~162G.Bon
Mardionetal, “Superfluid helium bathfor
superconducting magnets") has been developed. This device divides the inside of a container 1 into upper and lower parts by a perforated plate 2, and has first and second magnets placed above and below the perforated plate 2.
Helium tanks 3 and 4 are formed respectively, and
A heat exchanger 5 is provided around the outer periphery of the second helium tank 4. He is supplied to the heat exchanger 5 from the first helium container 3, and the pressure of the supplied He is reduced by the vacuum pump 6. The He in the second helium container is cooled by the heat of vaporization of He at this time. Note that 7 in the figure is a safety valve that closes the hole drilled in the perforated plate 2, and 8 in the figure is an auxiliary heat exchanger that cools He supplied from the first helium container 3 to the heat exchanger 5. . Further, numeral 9 in the figure is a superconducting pulsed magnet that is immersed in He and maintained at an ultra-low temperature.

However, if you operate the vacuum pump 6 now,
He in the first helium tank 3 is transferred to the auxiliary heat exchanger 8
is guided to the heat exchanger 5 via. The He introduced into the heat exchanger 5 is depressurized and vaporized, but the heat of vaporization at this time causes the He in the second helium tank 4 to
is cooled. Therefore, the He in the second helium tank 4 keeps the electromotive conductive pulsed magnet 9 at an extremely low temperature and in a superfluid state. Further, when the temperature of He decreases and its volume decreases, He is supplied from the first helium tank 3 to the second helium tank 4 through the perforated plate 2 by the amount of the decrease. In this way, He is retained and generated.

However, this type of device has the following problems. That is, as the perforated plate 2,
Ideally, it would be something that easily allows He to pass through, does not lower the internal pressure of the second helium tank 4, and has excellent heat insulation properties, but at present, such a material does not exist. For example, if the heat insulation properties of the porous plate 2 are poor, the heat of He in the first helium tank 3 will penetrate into the He in the second helium tank 4, making He unstable and causing performance degradation. Furthermore, in order to perform maintenance and inspection of the superconducting pulsed magnet 9 immersed in He, it was necessary to remove the perforated plate 2 from the container 1 and to take out the magnet 9 from the upper part of the container 1, which was extremely troublesome. .

The present invention was made in consideration of the above circumstances, and
The purpose of this is to improve the insulation properties between He and He, to stably retain and generate He, and to improve the maintenance and inspection of superconducting pulsed magnets etc. that are immersed in He. The object of the present invention is to provide a superfluid helium cryogenic container that can facilitate the process.

That is, in the present invention, first and second containers containing He and He are formed independently, a valve is provided to communicate between the containers, and the heat of vaporization of He in the first container is used to in container 2
The above objective is achieved by providing a heat exchanger for cooling He and further providing a lid for liquid-tightly sealing the second container against He.

Hereinafter, details of the present invention will be explained with reference to illustrated embodiments.

FIG. 2 is a schematic cross-sectional view showing a schematic configuration of an embodiment of the present invention. In the figure, reference numeral 10 denotes a cylindrical external container with a bottom, and a lid 11 is attached to the top opening of the container 10. The outer container 10 accommodates first and second helium containers 12 and 13, a heat exchanger 14, an auxiliary heat exchanger 15, first and second valves 16 and 17, and the like. A first helium container 12 is arranged in the center of the container 10, and a helium injection pipe 18 penetrating the lid 11 is connected to this helium container 12. The helium container 12 is configured to contain He. The second helium container 13 is disposed below the first helium container 12, and this helium container 13 includes the lid 11 and the container 12.
A helium injection pipe 19 passing through is connected. The helium container 13 is configured to contain He. The second helium container 13 is a bottomed cylindrical body with the opening facing downward, and a lid 21 is attached to the opening via a metal O-ring seal 20 as shown in FIG. It is worn. In other words, the metal O-ring seal 20 is made by silver-plating the outer circumferential surface of a SUS pipe.
The lid body 21 is attached to the lower surface of the container 13 via bolts 22 and nuts 23. With this seal, the second helium container 13 is liquid-tightly sealed even against superfluid helium. Further, the first and second helium containers 12 and 13 are communicated via a first valve 16. Note that the valve 16 is connected to the container 1.
The opening/closing is controlled by an external lever or the like.

On the other hand, the heat exchanger 14 is formed in an annular shape and is housed in the second helium container 13. He in the first helium container 12 is introduced into the heat exchanger 14 via a second valve 17 (Joule-Thompson valve) and an auxiliary heat exchanger 15. The pressure inside the heat exchanger 14 is reduced by a vacuum pump 24 provided outside the container 10.

In addition, the broken line 25 in the figure is the liquid nitrogen shield plate maintained at about 77K, and the line 26 in the figure is the outer container 1.
These are wheels for moving 0. Further, the superconducting pulsed magnet 30 is housed in the second helium container 13, and its lead 31 is led out of the container 10 via the first helium container 12 and the lid 11.

The operation of this device configured in this way will be explained.

First, the first and second helium containers 12,1
A predetermined amount of He is injected into the chamber. Then, when the vacuum pump 24 is activated, the first helium container 1
He in the heat exchanger 2 is cooled through the auxiliary heat exchanger 15 and introduced into the heat exchanger 14. He introduced into the heat exchanger 14 is depressurized and vaporized, but due to the heat of vaporization at this time, the heat in the second helium container 13 is
He is cooled and gradually becomes He. Note that at this time, the first valve 16 is closed.

Now, all of the inside of the second helium container 13 is Helium.
At the point in time, the superconducting pulsed magnet 30 is energized. Since the superconducting pulsed magnet 30 is maintained at an ultra-low temperature in this state, it operates normally, but the operation generates some heat. This heat is
This is transmitted to He and increases the temperature of He, but since He is cooled in the heat exchanger 14, He maintains a superfluid state.
On the other hand, when the temperature of He decreases and its volume decreases, the first valve 16 is opened by a predetermined amount to transfer He from the first helium container 12 to the second helium container 13.
Supply He. As a result, the pressure inside the second helium container 13 is always constant. Here, the first
When the valve 16 is closed, the amount of heat that permeates from the He in the first helium container 12 to the He in the second helium container 13 via the valve 16 is extremely small. Therefore, the second
Helium in the first helium container 13 will not become unstable due to heat invasion from He in the first helium container 12. In this way, He is generated and retained.

In this way, in this device, the first
a helium container 12 and a second helium container 12 containing He.
Helium containers 13 are independently provided, and these first and second helium containers 13 are communicated via a valve 16, and a heat exchanger 14 is used to supply Helium.
in the second helium container 13 using the heat of vaporization of
I am trying to cool He. Therefore,
It is possible to improve the heat insulation properties between the first and second helium containers 12 and 13, and it is possible to extremely reduce heat intrusion from He to He. Therefore, stable generation and retention of He can be achieved. Moreover, in this device, the second helium container 13
Since the metal O-ring 20 and the lid body 21 are used to seal liquid-tightly against He, the superconducting pulsed magnet 30 can be installed by simply removing the lid body 21 from the second helium container 13. It can be taken out from the container 13. Therefore, compared to conventional devices, the superconducting pulsed magnet 30 can be maintained and inspected much more easily. Furthermore, since the heat exchanger 14 is disposed inside the second helium container 13, the heat exchanger 14
4 will be in direct contact with He in the container 13, and the cooling effect of He can be improved. Furthermore, since the valve 16 is used, He flows from the first helium container 12 to the second helium container 13.
It has the advantage of being able to freely vary the flow rate.

Note that this invention is not limited to the embodiments described above. For example, the means for sealing the second helium container is not limited to the metal O-ring seal and the lid, but any means that can be liquid-tightly sealed against He may be used.
Further, the position where the valve 17 is provided is not limited to between the first helium container 12 and the auxiliary heat exchanger 15, but may be between the auxiliary heat exchanger 15 and the heat exchanger 14.
Further, the shapes, volumes, etc. of the first and second helium containers may be determined as appropriate according to specifications. Furthermore, it goes without saying that the present invention can be applied to various types of equipment used at extremely low temperatures instead of the superconducting pulsed magnet. In addition, various modifications can be made without departing from the gist of the invention.

[Brief explanation of the drawing]

Fig. 1 is a schematic cross-sectional view showing the general structure of a conventional device, Fig. 2 is a schematic cross-sectional view showing the schematic structure of an embodiment of the present invention, and Fig. 3 is an enlarged cross-sectional view showing the main mechanism of the above embodiment. It is. DESCRIPTION OF SYMBOLS 10... External container, 11... Lid body, 12... First helium container, 13... Second helium container, 14... Heat exchanger, 16... Valve, 20...
...Metal O-ring seal, 21...Lid body, 24...
...Vacuum pump, 30...Superconducting pulsed magnet.

Claims (1)

[Claims] 1 first and second helium containers containing liquid helium; a valve that communicates the first and second helium containers; a heat exchanger that cools liquid helium in a second helium container into superfluid helium;
1. A superfluid helium cryogenic container characterized by comprising a lid body for liquid-tightly sealing the helium container against superfluid helium.