He4 supercurrent suppression structure for dilution refrigerator

Abstract

The utility model discloses a He4 superflow suppression structure for a dilution refrigerator. The He4 superflow suppression structure comprises a distillation chamber, the reverse knife edge pipe is communicated with the distillation chamber; the sealing pipe is arranged outside the distillation chamber and sleeves the outer part, protruding out of the surface of the distillation chamber, of the reverse knife edge pipe; the suction pipe is communicated with the reverse knife edge pipe; the umbrella-shaped structure is fixed to the top of the inner wall of the distillation chamber and annularly arranged outside the reverse knife edge pipe, and during use, the climbing distance of He4 in the vertical direction is shortened through the multi-layer structure in the umbrella-shaped structure. According to the utility model, the umbrella-shaped inhibition structure and the reverse knife edge pipe structure are combined, so that the climbing problem of the superflow He4 in the distillation chamber is effectively prevented. The dilution refrigerator can work more reliably and stably, and the refrigeration efficiency is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of extremely low temperature refrigeration, in particular to a He4 superflow suppression structure for a dilution refrigerator. Background Art

[0002] Cryogenic thermostats are widely used in scientific research. Ultra-low temperature thermostats (mK level) are the most complex type of cryogenic thermostats. At present, most ultra-low temperature thermostats obtain ultra-low temperature environments through He3 / He4 dilution cycles. The dilution cycle refrigeration of the dilution refrigerator requires that the He4 mixing ratio in the circulating helium cannot exceed 10%, otherwise the dilution refrigeration cycle will fail. Under standard atmospheric pressure, when the temperature drops below 2.17k, He4 liquid will experience superfluidity, that is, He4 liquid will crawl along the wall, generating a thermo-mechanical effect, causing heat leakage in the distillation chamber. At the same time, during the climbing process of He4, the temperature zone gradually rises, causing He4 to gradually vaporize, causing the He4 mixing ratio in the helium to exceed 10%, resulting in the failure of dilution refrigeration.

[0003] In order to solve the above problems, the Chinese patent with publication number CN112146311A provides a technical solution, which adopts a combination of a reverse knife-edge tube and a forward knife-edge tube. Although it can suppress the climbing phenomenon of He4 to a certain extent, the combination of the reverse knife-edge tube and the forward guide tube will extend the climbing path. In the process of suppressing the climbing phenomenon, a thermo-mechanical effect will still be generated, causing heat leakage in the distillation chamber. Utility Model Content

[0004] The utility model aims to solve the shortcomings in the prior art and proposes a He4 superflow suppression structure for a dilution refrigerator.

[0005] In order to achieve the above-mentioned purpose, the utility model adopts the following technical scheme: a He4 superflow suppression structure for a dilution refrigerator, comprising a distillation chamber, including:

[0006] a reverse knife-edge pipe, connected to the distillation chamber;

[0007] A sealing tube, arranged outside the distillation chamber and sleeved on the outside of the reverse knife-edge tube protruding from the surface of the distillation chamber;

[0008] A suction tube, connected to the reverse knife-edge tube;

[0009] The tip drainage structure is fixed to the top of the inner wall of the distillation chamber and is arranged around the outside of the reverse knife-edge tube. When in use, the multi-layer structure in the tip drainage structure shortens the vertical climbing distance of He4.

[0010] As a further description of the above technical solution, the cross-section of the tip drainage structure is an umbrella-shaped structure or a drainage structure with a tip at the bottom.

[0011] As a further description of the above technical solution, the umbrella-shaped structure includes a multi-layer suppression structure centered on the reverse knife-edge tube, and the thickness of the suppression structure tends to gradually decrease in the direction away from the top of the inner wall of the distillation chamber.

[0012] As a further description of the above technical solution, the inhibition structure is a circular ring structure.

[0013] As a further description of the above technical solution, the suppression structure is provided with at least two layers.

[0014] As a further description of the above technical solution, there are gaps in the horizontal direction between adjacent suppression structures, between the suppression structure and the inner wall of the distillation chamber, and between the suppression structure and the outer wall of the reverse knife-edge tube.

[0015] As a further description of the above technical solution, the tip of the reverse knife-edge tube extends into the interior of the distillation chamber, and the reverse knife-edge tube and the sealing tube are integrally formed or welded.

[0016] As a further description of the above technical solution, the length of the reverse knife-edge tube extending into the distillation chamber is the same as the length of the umbrella-shaped structure.

[0017] As a further description of the above technical solution, the reverse knife-edge tube, the sealing tube, the umbrella-shaped structure and the distillation chamber are all made of 316 stainless steel to reduce heat leakage;

[0018] The umbrella-shaped structure is integrally formed or welded with the inner wall of the distillation chamber.

[0019] As a further description of the above technical solution, a base is installed at the bottom of the distillation chamber, a sealing plug is arranged on the base, and a steering valve is connected to the base.

[0020] The utility model has the following beneficial effects:

[0021] 1. The utility model adopts an umbrella-shaped suppression structure combined with a reverse knife-edge tube structure to effectively prevent the climbing problem of superfluid He4 in the distillation chamber. It can make the dilution refrigerator work more reliably and stably, improve the refrigeration efficiency, save He3 usage, reduce energy waste, and have significant economic benefits.

[0022] 2. The utility model aims at suppressing the climbing of He4 superfluid over a long path, and directly adds an umbrella-shaped suppression structure on the inner wall of the distillation chamber. The multi-stage umbrella-shaped suppression structure effectively suppresses the climbing problem of superfluid He4, and effectively shortens the path of the suppression structure, avoids the generation of thermal-mechanical effects, and reduces heat leakage losses. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a cross-sectional view of the He4 superflow suppression structure for a dilution refrigerator proposed by the utility model.

[0024] Legend:

[0025] 1. Distillation chamber; 2. Reverse knife-edge tube; 3. Sealing tube; 4. Suction tube; 5. Umbrella-shaped structure; 6. Ring structure; 7. Base; 8. Sealing plug; 9. Steering valve. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0027] The embodiment of the utility model solves the problem in the prior art that when the temperature drops below a certain threshold, the He4 liquid will experience a climbing phenomenon, thereby causing refrigeration failure. The existing dilution refrigerator usually only designs a forward knife-edge tube in the sealing tube 3, and only the tip size of the forward knife-edge tube is at the nanometer level, which can effectively suppress the superfluid climbing. However, in the actual processing process, due to process limitations, it is difficult to meet the nanometer-level processing requirements, and another means is to combine the reverse knife-edge tube 2 with the forward knife-edge tube to suppress the superfluid He4 climbing phenomenon, thereby solving the problem of refrigeration failure. However, the combination of the forward knife-edge tube and the reverse knife-edge tube 2 will make the suppression path longer, produce a thermo-mechanical effect, and cause the distillation chamber 1 to have a large heat leakage loss. The technical concept of the present application is that by arranging an umbrella-shaped structure 5 in the distillation chamber 1, the climbing phenomenon can be suppressed, and at the same time, the length of the suppression path is reduced, further reducing the thermo-mechanical effect, and reducing the heat leakage loss of the distillation chamber 1.

[0028] The utility model is described in conjunction with specific embodiments. Figure 1 The utility model provides an embodiment: a He4 superflow suppression structure for a dilution refrigerator, which specifically includes a distillation chamber 1, a base 7 is sealedly installed at the bottom of the distillation chamber 1, and a sealing plug 8 and a steering valve 9 are provided on the base 7.

[0029] At the top of the distillation chamber 1, there is a reverse knife-edge tube 2 that passes through the top of the inner wall of the distillation chamber 1. The reverse knife-edge tube 2 refers to a tube with a knife edge at the bottom and extending into the interior of the distillation chamber 1, and a sealing tube 3 is welded to the outside of the reverse knife-edge tube 2 that protrudes from the distillation chamber 1. The sealing tube 3 is provided to achieve sealing of the welding point between the distillation chamber 1 and the reverse knife-edge tube 2, and the reverse knife-edge tube 2 is connected to the suction tube 4.

[0030] A tip drainage structure is arranged at the top of the inner wall of the distillation chamber 1. Preferably, the tip drainage structure is an umbrella-shaped structure 5 or other structure with a tip at the bottom. The umbrella-shaped structure 5 is arranged around the tip of the blade of the reverse blade tube 2, and the umbrella-shaped structure 5 is composed of a multi-layer suppression structure. The suppression structure is specifically a hollow circular ring structure 6, and the thickness of the suppression structure tends to gradually decrease in the direction away from the top of the inner wall of the distillation chamber 1. In short, in the cross-sectional view, the lower end of the suppression structure is a needle-shaped structure. When He4 climbs along the inner wall of the distillation chamber 1, the climbing distance in the vertical direction can be shortened by the multi-layer suppression structure, thereby reducing the thermal-mechanical effect, thereby reducing the heat leakage loss of the distillation chamber 1.

[0031] Furthermore, since the lower end of the suppression structure is a needle-shaped structure, when the He4 liquid crawls on the suppression structure, it gathers at the tip when it crawls to the lower edge of the suppression structure, and then falls back into the interior of the distillation chamber 1, so that the He4 liquid can be reused.

[0032] In the umbrella-shaped structure 5, there are gaps in the horizontal direction between the multiple layers of suppression structures inside it. Similarly, there are gaps in the horizontal direction between the inner wall of the distillation chamber 1 and the outermost layer of suppression structure, and there are gaps between the innermost layer of suppression structure and the outer wall of the reverse knife-edge tube 2 extending into the distillation chamber 1. Therefore, when the He4 liquid climbs along the inner wall of the distillation chamber 1 to the reverse knife-edge tube 2, it needs to cross multiple layers of gaps, which is quite difficult. Therefore, the climbing phenomenon of He4 can be effectively suppressed to ensure the stability of dilution refrigeration.

[0033] Furthermore, since the tip of the reverse knife-edge tube 2 extends into the interior of the distillation chamber 1, and the length of the reverse knife-edge tube 2 extending into the distillation chamber 1 is not less than the length of the umbrella-shaped structure 5, in this embodiment, the length of the reverse knife-edge tube 2 extending into the interior of the distillation chamber 1 is equal to the length of the umbrella-shaped structure 5. When the He4 liquid climbs to the tip of the reverse knife-edge tube 2, the liquid will gather at the tip and flow back into the interior of the distillation chamber 1, thereby further suppressing the climbing phenomenon of the He4 liquid and ensuring the stability of the dilution refrigeration. In addition, the reverse knife-edge tube 2 and the sealing tube 3 are integrally formed or welded, and the umbrella-shaped structure 5 and the inner wall of the distillation chamber 1 are integrally formed or welded to effectively improve the connection strength.

[0034] The reverse knife-edge tube 2, the sealing tube 3, the umbrella-shaped structure 5 and the distillation chamber 1 are all made of 316 stainless steel, which has higher welding reliability and can reduce heat leakage.

[0035] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A He4 superflow suppression structure for a dilution refrigerator, comprising a distillation chamber, characterized in that: include: a reverse knife-edge pipe, connected to the distillation chamber; A sealing tube, arranged outside the distillation chamber and sleeved on the outside of the reverse knife-edge tube protruding from the surface of the distillation chamber; A suction tube, connected to the reverse knife-edge tube; The tip drainage structure is fixed to the top of the inner wall of the distillation chamber and is arranged around the outside of the reverse knife-edge tube. When in use, the multi-layer structure in the tip drainage structure shortens the vertical climbing distance of He4.

2. The He4 superflow suppression structure for a dilution refrigerator according to claim 1, characterized in that: The cross section of the tip drainage structure is an umbrella-shaped structure or a drainage structure with a tip at the bottom.

3. The He4 superflow suppression structure for a dilution refrigerator according to claim 2, characterized in that: The umbrella-shaped structure comprises a multi-layered suppression structure centered on the reverse knife-edge tube, and the thickness of the suppression structure gradually decreases in a direction away from the top of the inner wall of the distillation chamber.

4. The He4 superflow suppression structure for a dilution refrigerator according to claim 3, characterized in that: The inhibition structure is a circular ring structure.

5. The He4 superflow suppression structure for a dilution refrigerator according to claim 3, characterized in that: The restraining structure is provided with at least two layers.

6. The He4 superflow suppression structure for a dilution refrigerator according to claim 3, characterized in that: There are gaps in the horizontal direction between adjacent suppression structures, between the suppression structure and the inner wall of the distillation chamber, and between the suppression structure and the outer wall of the reverse knife-edge tube.

7. The He4 superflow suppression structure for a dilution refrigerator according to claim 1, characterized in that: The tip of the reverse knife-edge tube extends into the interior of the distillation chamber, and the reverse knife-edge tube is integrally formed or welded with the sealing tube.

8. The He4 superflow suppression structure for a dilution refrigerator according to claim 6, characterized in that: The length of the reverse knife-edge tube extending into the distillation chamber is the same as the length of the umbrella-shaped structure.

9. The He4 superflow suppression structure for a dilution refrigerator according to claim 3, characterized in that: The reverse knife-edge tube, the sealing tube, the umbrella-shaped structure and the distillation chamber are all made of 316 stainless steel to reduce heat leakage; The umbrella-shaped structure is integrally formed or welded with the inner wall of the distillation chamber.

10. The He4 superflow suppression structure for a dilution refrigerator according to claim 1, characterized in that: A base is installed at the bottom of the distillation chamber, a sealing plug is arranged on the base, and a steering valve is connected to the base.

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