JPH0687445B2 - Cryogenic container - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a cryogenic container of a superconducting magnet for a nuclear magnetic resonance apparatus or the like.

[Prior Art] FIG. 2 shows a conventional cryogenic container, in which 1 is a superconducting coil, 2 is a cryogen such as liquid helium for cooling the superconducting coil 1, 3 is a superconducting coil 1 and a cryogen. A cryogen storage container for storing 2 is a shield tank, 5 is a vacuum heat insulation tank for keeping the inside in a vacuum state. 6 is a support material for supporting the superconducting coil 1 to the shield tank 4, and 7
Is an injection pipe for supplying a cryogen.

In the conventional structure, the surfaces of the cryogen storage container 3, the shield tank 4, and the vacuum heat insulation tank 5 are buffed in order to reduce heat intrusion due to heat radiation from the outside of the cryogen storage container 5.

Next, the effect of reducing heat radiation by buffing will be described. The superconducting coil 1 is used after being cooled to a cryogenic temperature range by a cryogen 2. For this reason, if heat enters from this portion from the outside, the cryogen 2 is gasified and the amount of the cryogen 2 consumed increases. For example, when the cryogen 2 is operated as a magnetic resonance apparatus, the price of the cryogen 2 is high and the operation is also performed. Maintenance costs may increase.

Here, the heat that has entered the vacuum heat insulating tank 5 from the outside radiates to the shield tank 4 inside the vacuum heat insulating tank 5, and the heat enters through the support material 6 and the liquid injection pipe 7. Further, the radiation is also radiated from the shield tank 4 to the cryogen storage container 3, and heat is penetrated by the support material 6 and the liquid injection pipe 7. Of these invasion heat, heat transfer by radiation is expressed by the following equation.

Where W: amount of radiant heat transfer δ: Poltzmann constant A ₁ : surface area of inner container A ₂ : surface area of outer container ε ₁ : emissivity of inner container ε ₂ : emissivity of outer container T ₁ : inner container temperature T ₂ : The temperature of the outer container, therefore, the amount of heat entering by radiation becomes smaller as the emissivity of the flat plate becomes smaller. Therefore, the amount of heat entering from the outside is reduced by buffing the surfaces of the vacuum heat insulating tank 5, the shield tank 4, and the cryogen storage container 3 to reduce the emissivity.

[Problems to be solved by the invention]

The conventional cryogenic container is configured as described above, and buffing was performed to reduce the emissivity of the surface between the heat penetration paths in order to reduce the amount of heat penetration from the outside. There was a problem that the cost was high in performing the processing.

The present invention has been made to solve the above problems, and an object thereof is to obtain a cryogenic container having a surface having an emissivity equivalent to that of buffing at a low cost as an alternative to buffing.

[Means for solving problems]

The cryogenic container according to the present invention is one in which a metal foil having an emissivity equivalent to that of the buffing surface is attached to the surfaces of the cryogen storage container, the shield tank, and the vacuum heat insulating tank that constitute the container.

[Action]

According to the present invention, by attaching a metal foil having an emissivity equivalent to that of the buffing surface to the surfaces of the cryogen storage container, the shield tank, and the vacuum heat insulating tank that constitute the cryogenic container, the effect of reducing heat intrusion from the outside There is.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. In the figure, 1 to 7 are the same as the above conventional device. 8
Is a radiant heat reflecting material of metal foil, which is attached to the surfaces of the cryogen storage container 3, the shield tank 4, and the vacuum heat insulating tank 5 to prevent heat from entering due to heat radiation from the outside.

Next, the effect of reducing the heat radiation by the metal foil 8 in the present invention will be described. The heat entering the vacuum heat insulating tank 5 from the outside radiates to the shield tank 4 inside the vacuum heat insulating tank 5,
Heat is invaded by the support material 6 and the liquid injection pipe 7. Further, the radiation is also radiated from the shield tank 4 to the cryogen storage container 3, and heat is invaded by the support material 6 and the liquid injection pipe 7. The heat transfer by internal radiation of these invasion heats is similar to the description of the operation of the prior art.

Therefore, the amount of heat penetrating by radiation becomes smaller as the emissivity of the flat plate surface becomes smaller. Therefore, vacuum insulation tank 5, shield tank 4,
By attaching a metal foil 8 having a surface equivalent to the surface obtained by buffing the metal surface to the surface of the cryogen storage container 3, it is possible to reduce the amount of heat intrusion from the outside. In addition, the metal foil 8 is applied to the vacuum heat insulation tank 5, the shield tank 4, and the cryogen storage container 3
By attaching to the surface of the buffing surface, a radiation surface equivalent to the buffing surface can be constructed at a lower processing cost than the conventional buffing processing.

Although the cryogenic container is described in the above embodiment,
It may be used to reduce the radiant heat of other low temperature containers or cold storage containers, structural parts for the purpose of heat insulation, etc. As the metal foil, for example, copper foil or aluminum foil may be used.

〔The invention's effect〕

As described above, according to the present invention, since the cryogen storage container, the shield tank, and the metal foil are attached to the surface of the cryogenic container, the processing cost is low as compared with the conventional buffing process, and moreover, the same as the buffing process. It has the effect of reducing heat penetration.

[Brief description of drawings]

FIG. 1 shows an embodiment of a cryogenic container according to the present invention, (a) is a front sectional view and (b) is a plan sectional view. FIG. 2 shows a conventional cryogenic container, in which C is a front sectional view and D is a plan sectional view. In the figure, 1 is a superconducting coil, 2 is a cryogen, 3 is a cryogen storage container, 4 is a shield tank, 5 is a vacuum heat insulation tank, 6 is a support material, 7
Is a liquid injection pipe, and 8 is a radiant heat reflector. The same reference numerals in the drawings indicate the same or corresponding parts.

Claims (2)

[Claims] 1. A cryogen storage container for storing a cryogenic cryogen, a vacuum insulation tank for accommodating the cryogen storage container for vacuum heat insulation, and radiant heat or closing between the cryogen storage container and the vacuum insulation tank. In a cryogenic container equipped with a heat shield tank, a metal foil having an emissivity similar to that of a buffed surface is directly attached to the surface of each of the above containers. 2. The cryogenic container according to claim 1, wherein the metal foil is made of copper foil or aluminum foil.