High vacuum maintained liquid helium Dewar

Abstract

The invention discloses a high vacuum maintained liquid helium Dewar. The liquid helium Dewar comprises a vacuum outer cavity, a liquid helium cavity and a liquid helium diameter pipe. A vacuum electric connector and a vacuumizing opening are arranged on the outer surface of the vacuum outer cavity, the vacuum electric connector extends to a vacuum interlayer, and the vacuumizing opening is communicated with the vacuum interlayer. At least one air suction device is arranged on the inner surface of the vacuum outer cavity and electrically connected with the vacuum electric connector. At least one adsorption device is arranged on the outer surface of the liquid helium cavity, an adsorption medium is arranged in the adsorption device, the adsorption device is provided with a heating device, and the heating device is electrically connected with the vacuum electric connector. According to the liquid helium Dewar, the liquid helium Dewar can maintain a high vacuum degree for a long time, can achieve a very good heat insulation effect, can maintain a low volatilization rate for a long time, and has very good practicability.

Description

technical field [0001] The invention relates to the technical field of liquid helium Dewar structures, in particular to a high vacuum maintained liquid helium Dewar. Background technique [0002] Liquid helium dewars are often used in the storage and transportation of liquid helium. Its main function is to ensure that the Dewar can maintain an extremely low volatilization rate of liquid helium during storage and transportation, that is, the volatilization rate must be less than 1% per 24 hours; therefore, liquid helium Helium Dewar needs to have good thermal insulation performance. Generally, heat leakage is reduced by reducing radiation heat transfer, heat conduction and convection heat transfer, so that liquid helium Dewar can meet the requirements. [0003] In the liquid helium Dewar, there is a vacuum interlayer between the vacuum outer chamber and the liquid helium chamber, and there are cold screens, multi-layer heat insulation, thermal connection pipelines and suspens...

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Problems solved by technology

[0003] In the liquid helium Dewar, there is a vacuum interlayer between the vacuum outer chamber and the liquid helium chamber, and there are cold screens, multi-layer heat insulation, thermal connection pipelines and suspension parts in the vacuum interlayer, etc., through assembly and / or welding, etc. The forms are assembled together; the vacuum interlayer needs to maintain a high vacuum continuously, that is, less than 1.0*10e -3 Pa, to achieve the purpose of heat insulation; the higher the vacuum degree of the vacuum interlayer, the better the corresponding heat insulation effect. Some liquid helium Dewars will experience problems such as a decrease in vacuum degree and an increase in volatilization rate after running for a certain period of time. The main reasons are: The materials in the vacuum interlayer continue to outgas, and the external environment will slowly leak helium and hydrogen into the vacuum interlayer. These gases cannot be condensed and adsorbed on the outer surface of the liquid helium cavity, causing the built-in gas adsorber in the vacuum interlayer to quickly reaches saturation, causing vacuum to deteriorate

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