A liquid helium dewar for maintaining high vacuum

Abstract

The present invention discloses a liquid helium dewar for maintaining high vacuum, the liquid helium dewar comprises a vacuum outer cavity, a liquid helium cavity and a liquid helium diameter tube; a vacuum electrical connector and a vacuum port are arranged on the outer surface of the vacuum outer cavity, the vacuum electrical connector extends to the vacuum interlayer, and the vacuum port is connected to the vacuum interlayer; at least one suction device is arranged on the inner surface of the vacuum outer cavity, and the suction device is electrically connected to the vacuum electrical connector; at least one adsorption device is arranged on the outer surface of the liquid helium cavity, an adsorption medium is built in the adsorption device, and the adsorption device is provided with a heating device, and the heating device is electrically connected to the vacuum electrical connector. In the embodiment of the present invention, the liquid helium dewar can maintain a high vacuum for a long time, can achieve a good insulation effect, can maintain a low volatility for a long time, and has good practicality.

Description

Technical Field

[0001] The invention relates to the technical field of liquid helium dewar structures, and in particular to a liquid helium dewar maintained with high vacuum. Background Art

[0002] Liquid helium dewar is often used in the storage and transportation of liquid helium. Its main function is to ensure that the dewar can maintain an extremely low liquid helium volatility during the storage and transportation process, that is, the volatility every 24 hours must be less than 1%; therefore, the liquid helium dewar needs to have good thermal insulation performance. Generally, heat leakage is reduced by reducing radiation heat transfer, reducing heat conduction and reducing convection heat transfer, so that the liquid helium dewar meets the requirements.

[0003] In the liquid helium dewar, there is a vacuum interlayer between the vacuum outer cavity and the liquid helium cavity. The vacuum interlayer contains cold shields, multi-layer insulation, thermal connection pipes and hanging parts, etc., which are assembled together through assembly and / or welding. The vacuum interlayer needs to maintain high vacuum continuously, that is, less than 1.0*10e -3 Pa is required to achieve the purpose of thermal insulation; the higher the vacuum degree of the vacuum interlayer, the better the corresponding thermal insulation effect. Some liquid helium dewars will experience a decrease in vacuum degree and an increase in volatility after running for a 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 condense and adsorb on the outer surface of the liquid helium cavity, causing the gas adsorber built into the vacuum interlayer to quickly reach saturation, causing the vacuum to deteriorate. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art. The present invention provides a liquid helium dewar for maintaining high vacuum. The liquid helium dewar can maintain high vacuum for a long time, can achieve good insulation effect, can keep low volatility for a long time, and has good practicality.

[0005] Accordingly, an embodiment of the present invention provides a liquid helium dewar for maintaining high vacuum, wherein the liquid helium dewar comprises a vacuum outer cavity, a liquid helium cavity and a liquid helium diameter tube;

[0006] The liquid helium cavity is arranged inside the vacuum outer cavity, and a vacuum interlayer is formed between the liquid helium cavity and the vacuum outer cavity;

[0007] One end of the liquid helium tube is in communication with the interior of the liquid helium cavity, and the other end of the liquid helium tube is in communication with the exterior of the vacuum outer cavity;

[0008] A vacuum electrical connector and a vacuum port are provided on the outer surface of the vacuum outer cavity, the vacuum electrical connector extends to the vacuum interlayer, and the vacuum port is communicated with the vacuum interlayer;

[0009] At least one suction device is provided on the inner surface of the vacuum outer cavity, and the suction device is electrically connected to the vacuum electrical connector;

[0010] At least one adsorption device is arranged on the outer surface of the liquid helium cavity, an adsorption medium is built in the adsorption device, and the adsorption device is provided with a heating device, and the heating device is electrically connected to the vacuum electrical connector.

[0011] In an optional implementation manner, the air getter device is a non-evaporable getter, and the non-evaporable getter has a non-evaporable getter built in.

[0012] In an optional implementation manner, the adsorption device is an activated carbon adsorber, and the adsorption medium is activated carbon bonded to or placed inside the activated carbon adsorber.

[0013] In an optional implementation manner, a vacuum flange is provided on the outer surface of the vacuum outer cavity, and the vacuum port is provided in the vacuum flange.

[0014] In an optional implementation manner, the liquid helium Dewar further includes a sealing flange, and the sealing flange is connected to the vacuum flange and seals the vacuum port.

[0015] In an optional implementation manner, an O-ring is provided between the sealing flange and the vacuum flange.

[0016] In an optional embodiment, a plurality of cold shields surrounding the liquid helium cavity are provided in the vacuum interlayer.

[0017] In an optional embodiment, the plurality of cold shields include a first cold shield, a second cold shield and a third cold shield sequentially arranged between the liquid helium cavity and the vacuum outer cavity, wherein:

[0018] The first cold screen is a 30K cold screen;

[0019] The second cold shield is a 77K cold shield, and the 77K cold shield is provided with multiple layers of thermal insulation;

[0020] The third cold shield is a 200K cold shield, and multiple layers of thermal insulation are arranged on the 200K cold shield.

[0021] In an optional implementation manner, the vacuum outer cavity is a 300K vacuum outer cavity.

[0022] In an optional implementation manner, the liquid helium chamber is a 4K liquid helium chamber.

[0023] The embodiment of the present invention provides a liquid helium dewar for maintaining high vacuum. In the liquid helium dewar, after the vacuum interlayer is evacuated, the air suction device can continuously absorb the gas in the vacuum interlayer, thereby improving the vacuum degree of the vacuum interlayer and maintaining the high vacuum degree for a long time. The adsorption medium in the adsorption device can adsorb difficult-to-condense gases such as hydrogen and helium in the vacuum interlayer, and can improve the speed and capacity of the adsorption of hydrogen and helium inside the liquid helium dewar, which can not only further improve the vacuum degree of the vacuum interlayer, but also prolong the time for the air suction device to adsorb to saturation, thereby maintaining the high vacuum degree for a long time. It can be seen that the liquid helium dewar can maintain a high vacuum degree for a long time, can achieve a good insulation effect, can maintain a low volatility for a long time, and has a good practical use effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 1 is an external structural diagram of a liquid helium dewar in an embodiment of the present invention;

[0026] Figure 2 is a diagram of the internal structure of a liquid helium dewar in an embodiment of the present invention;

[0027] Figure 3 It is a schematic diagram of the partial structure of the liquid helium Dewar in an embodiment of the present invention. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Figure 1 1 is an external structural diagram of a liquid helium dewar in an embodiment of the present invention. Figure 2 1 is a diagram of the internal structure of the liquid helium dewar in an embodiment of the present invention.

[0030] The embodiment of the present invention provides a liquid helium dewar for maintaining high vacuum, wherein the liquid helium dewar comprises a vacuum outer cavity 1, a liquid helium cavity 2 and a liquid helium diameter tube 3.

[0031] The liquid helium cavity 2 is disposed inside the vacuum outer cavity 1 , and a vacuum interlayer is formed between the liquid helium cavity 2 and the vacuum outer cavity 1 .

[0032] One end of the liquid helium diameter tube 3 is communicated with the interior of the liquid helium cavity 2, and the other end of the liquid helium diameter tube 3 is communicated with the exterior of the vacuum outer cavity 1. In a specific implementation, liquid helium can be transported to the interior of the liquid helium cavity 2 through the liquid helium diameter tube 3, and liquid helium can be extracted from the interior of the liquid helium cavity 2 through the liquid helium diameter tube 3.

[0033] A vacuum electrical connector 4 and a vacuum port 5 are provided on the outer surface of the vacuum outer cavity 1 .

[0034] The vacuum electrical connector 4 extends to the vacuum interlayer, and the vacuum electrical connector 4 is used to realize the electrical connection between the internal components and the external circuit.

[0035] The vacuum port 5 is in communication with the vacuum interlayer. In a specific implementation, a molecular pump or a low-temperature vacuum pump group is connected to the vacuum port 5 , and the vacuum interlayer can be vacuumed through the vacuum port 5 .

[0036] At least one suction device 11 is provided on the inner surface of the vacuum outer cavity 1, and the suction device 11 is electrically connected to the vacuum electrical connector 4. In a specific implementation, the suction device 11 is electrically connected to the vacuum electrical connector 4 through a wire, and an external power supply is electrically connected to the vacuum electrical connector 4 through an external circuit. After the vacuum interlayer is evacuated, the external power supply controls the operation of the suction device 11 through the vacuum electrical connector 4, and the suction device 11 absorbs the gas in the vacuum interlayer, thereby improving the vacuum degree of the vacuum interlayer.

[0037] At least one adsorption device 21 is provided on the outer surface of the liquid helium cavity 2, and an adsorption medium is built in the adsorption device 21, and the adsorption device 21 is provided with a heating device, and the heating device is electrically connected to the vacuum electrical connector 4. In a specific implementation, the adsorption medium in the adsorption device 21 can adsorb the hydrogen, helium and other difficult-to-condense gases in the vacuum interlayer, and other gases are condensed on the outer surface of the liquid helium cavity 2, which can not only further improve the vacuum degree of the vacuum interlayer, but also prolong the time for the gas absorption device 11 to adsorb to saturation, thereby maintaining a high vacuum degree for a long time; the heating device is electrically connected to the vacuum electrical connector 4 through a wire, and an external power supply is electrically connected to the vacuum electrical connector 4 through an external circuit. When the vacuum interlayer is evacuated, the external power supply controls the operation of the heating device through the vacuum electrical connector 4, and the heating device can heat the liquid helium dewar as a whole, evaporate the gas adsorbed by the adsorption medium, smoothly extract the gas adsorbed by the adsorption medium, and restore the efficiency of the adsorption saturated adsorption medium.

[0038] Specifically, the getter device 11 is a non-evaporable getter, and the non-evaporable getter has a non-evaporable getter built in it.

[0039] In a specific implementation, after the vacuum interlayer is evacuated, an external power source controls the operation of the non-evaporable getter through the vacuum electrical connector 4, discharges the non-evaporable getter, and adsorbs the gas in the vacuum interlayer, which can increase the vacuum degree by 1-2 orders of magnitude.

[0040] In addition, the non-evaporable getter in the non-evaporable getter can work multiple times. After the liquid helium Dewar has been running for a long time and the adsorption device 21 is saturated with adsorption, the external power supply controls the operation of the non-evaporable getter again through the vacuum electrical connector 4, discharges the non-evaporable getter again, and adsorbs the gas in the vacuum interlayer again, which can continuously improve the vacuum degree and reduce the volatility of liquid helium.

[0041] Specifically, the adsorption device 21 is an activated carbon adsorber, and the adsorption medium is activated carbon bonded or placed inside the activated carbon adsorber.

[0042] In a specific implementation, after the liquid helium is transported to the interior of the liquid helium cavity 2 through the liquid helium diameter tube 3, the adsorption capacity of the activated carbon is greatly enhanced, and the hydrogen, helium and other difficult-to-condense gases in the vacuum interlayer can be adsorbed, and other gases are condensed on the outer surface of the liquid helium cavity 2, thereby increasing the vacuum degree by 1-2 orders of magnitude, and finally reaching 1.0*10e -6 Pa or higher vacuum degree.

[0043] In addition, when the vacuum interlayer is evacuated, the heating device can heat the liquid helium Dewar as a whole to 45-120 degrees Celsius, heat the activated carbon in the activated carbon adsorber, evaporate the gas adsorbed by the activated carbon, smoothly extract the gas adsorbed by the activated carbon, and restore the efficiency of the saturated activated carbon.

[0044] Figure 3 It is a schematic diagram of the partial structure of the liquid helium Dewar in an embodiment of the present invention.

[0045] Specifically, a vacuum flange 12 is provided on the outer surface of the vacuum outer cavity 1 , and the vacuum port 5 is provided in the vacuum flange 12 .

[0046] In addition, the liquid helium Dewar further includes a sealing flange 6 , which is connected to the vacuum flange 12 and seals the vacuum port 5 .

[0047] In a specific implementation, when the vacuum degree at the vacuum port 5 reaches 1.0*10e -4After the vacuum degree reaches Pa or higher, the sealing flange 6 is connected to the vacuum flange 12 to seal the vacuum port 5.

[0048] Particularly, an O-ring 61 is provided between the sealing flange 6 and the vacuum flange 12 , and the O-ring 61 can seal the connection gap between the sealing flange 6 and the vacuum flange 12 , thereby achieving a better sealing effect.

[0049] Specifically, a plurality of cold shields surrounding the liquid helium cavity 2 are arranged in the vacuum interlayer, and the plurality of cold shields have a heat insulating effect on the liquid helium cavity 2 .

[0050] The plurality of cold shields include a first cold shield 71 , a second cold shield 72 and a third cold shield 73 which are sequentially arranged between the liquid helium cavity 2 and the vacuum outer cavity 1 .

[0051] Preferably, the first cold shield 71 is a 30K cold shield.

[0052] Preferably, the second cold shield 72 is a 77K cold shield, and multiple layers of thermal insulation are arranged on the 77K cold shield.

[0053] Preferably, the third cold shield 73 is a 200K cold shield, and multiple layers of thermal insulation are provided on the 200K cold shield.

[0054] Preferably, the vacuum outer cavity 1 is a 300K vacuum outer cavity.

[0055] Preferably, the liquid helium chamber 2 is a 4K liquid helium chamber.

[0056] The embodiment of the present invention provides a liquid helium dewar for maintaining high vacuum. In the liquid helium dewar, after the vacuum interlayer is evacuated, the air suction device 11 can continuously absorb the gas in the vacuum interlayer, thereby improving the vacuum degree of the vacuum interlayer and maintaining the high vacuum degree for a long time. The adsorption medium in the adsorption device 21 can adsorb difficult-to-condense gases such as hydrogen and helium in the vacuum interlayer, and can improve the speed and capacity of the adsorption of hydrogen and helium inside the liquid helium dewar, which can not only further improve the vacuum degree of the vacuum interlayer, but also prolong the time for the air suction device 11 to adsorb to saturation, thereby maintaining the high vacuum degree for a long time. It can be seen that the liquid helium dewar can maintain a high vacuum degree for a long time, can achieve a good insulation effect, can maintain a low volatility for a long time, and has a good practical use effect.

[0057] In addition, a high vacuum maintained liquid helium dewar provided in an embodiment of the present invention is introduced in detail above. Specific examples are used herein to illustrate the principle and implementation mode of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation mode and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A liquid helium dewar for maintaining high vacuum, characterized in that: The liquid helium dewar comprises a vacuum outer cavity, a liquid helium cavity and a liquid helium diameter tube; The liquid helium cavity is arranged inside the vacuum outer cavity, and a vacuum interlayer is formed between the liquid helium cavity and the vacuum outer cavity; One end of the liquid helium tube is in communication with the interior of the liquid helium cavity, and the other end of the liquid helium tube is in communication with the exterior of the vacuum outer cavity; A vacuum electrical connector and a vacuum port are provided on the outer surface of the vacuum outer cavity, the vacuum electrical connector extends to the vacuum interlayer, and the vacuum port is communicated with the vacuum interlayer; At least one suction device is provided on the inner surface of the vacuum outer cavity, and the suction device is electrically connected to the vacuum electrical connector; At least one adsorption device is arranged on the outer surface of the liquid helium cavity, an adsorption medium is built in the adsorption device, and the adsorption device is provided with a heating device, and the heating device is electrically connected to the vacuum electrical connector.

2. The liquid helium dewar according to claim 1, characterized in that: The air getter device is a non-evaporable getter, and the non-evaporable getter has a non-evaporable getter built in it.

3. The liquid helium dewar according to claim 1, characterized in that: The adsorption device is an activated carbon adsorber, and the adsorption medium is activated carbon bonded to or placed inside the activated carbon adsorber.

4. The liquid helium dewar according to claim 1, characterized in that: A vacuum flange is arranged on the outer surface of the vacuum outer cavity, and the vacuum port is arranged in the vacuum flange.

5. The liquid helium dewar according to claim 4, characterized in that: The liquid helium Dewar further comprises a sealing flange, which is connected to the vacuum flange and seals the vacuum port.

6. The liquid helium dewar according to claim 5, characterized in that: An O-ring is arranged between the sealing flange and the vacuum flange.

7. The liquid helium dewar according to claim 1, characterized in that: A plurality of cold screens surrounding the liquid helium cavity are arranged in the vacuum interlayer.

8. The liquid helium dewar according to claim 7, characterized in that: The plurality of cold shields include a first cold shield, a second cold shield and a third cold shield which are sequentially arranged between the liquid helium cavity and the vacuum outer cavity, wherein: The first cold screen is a 30K cold screen; The second cold shield is a 77K cold shield, and the 77K cold shield is provided with multiple layers of thermal insulation; The third cold shield is a 200K cold shield, and multiple layers of thermal insulation are arranged on the 200K cold shield.

9. The liquid helium dewar according to claim 1, characterized in that: The vacuum outer cavity is a 300K vacuum outer cavity.

10. The liquid helium dewar according to claim 1, characterized in that: The liquid helium cavity is a 4K liquid helium cavity.

Images