Enrichment device based on superfluid helium-3 and use method thereof

Abstract

The invention relates to the technical field of gas separation, and provides an enrichment device applying superfluid helium-3 and a using method thereof.The enrichment device comprises a first Dewar used for storing superfluid helium; the hot end structure and the cold end structure are both communicated with the first Dewar; the temperature of the first Dewar, the temperature of the hot end structure and the temperature of the cold end structure are all lower than 2.17 K, and the temperature of the hot end structure is higher than that of the cold end structure; and a helium-4 superfluid part in the superfluid helium flows to the hot end structure, and a helium-3 and helium-4 normal fluid part in the superfluid helium flows to the cold end structure. On the basis of a two-fluid theoretical model, the device suitable for generating internal convection by superfluid helium is designed by applying the thermomechanical effect of superfluid helium, so that the separation degree of superfluid and normal fluid is relatively high, and the effect of enriching helium-3 is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of gas separation, and in particular to an enrichment device applying superfluid helium-3 and a using method thereof. Background Art

[0002] Helium-3 is a rare isotope of helium. The boiling point of He3 under normal pressure is 3.19K, and the superfluid transition temperature is 2.6mK. It is the core working fluid of devices such as mK-level dilution refrigerators and clean nuclear fusion, and is a strategic material essential for ensuring the development of China's quantum computers and the long-term acquisition of safe fusion energy. Helium-3 in nature is formed by the β decay of tritium nuclei, and its natural abundance is very small. The content of helium-3 in the atmosphere is about 10 -12 order of magnitude, and in some helium-containing natural gases, the content of helium-3 is about 10 -10 ~10 -9 order of magnitude.

[0003] Currently, helium isotope separation methods include gas diffusion method, cooling method, normal temperature gas separation method, etc. Among them, the gas diffusion method has low separation efficiency, the cooling method requires a large amount of liquid helium and complex equipment, and the normal temperature gas separation method requires complex separation columns and operation processes, and the separation rate of helium-3 is very slow.

[0004] Therefore, how to provide an enrichment device for helium-3 with high separation efficiency is a technical problem that those skilled in the art need to solve urgently. Summary of the Invention

[0005] The present invention provides an enrichment device based on superfluid helium-3 and a using method thereof, which are used to solve the defect that helium-3 has a low concentration and is difficult to enrich in the prior art, and realize that the superfluid helium undergoes sufficient internal convection by using the temperature difference between the hot end structure and the cold end structure, thereby improving the separation rate.

[0006] The present invention provides an enrichment device based on superfluid helium-3, including:

[0007] A first Dewar for storing superfluid helium;

[0008] A hot end structure and a cold end structure, both of which are communicated with the first Dewar;

[0009] The temperatures of the first Dewar, the hot end structure and the cold end structure are all less than 2.17K, and the temperature of the hot end structure is greater than the temperature of the cold end structure;

[0010] The helium-4 superfluid part in the superfluid helium flows to the hot end structure, and the helium-3 and helium-4 normal fluid parts in the superfluid helium flow to the cold end structure.

[0011] An enrichment device based on superfluid helium-3 provided by the present invention further includes a flushing pipe, which is horizontally arranged and has its top connected to the first Dewar; and one end of the flushing pipe is connected to the hot end structure, and the other end is connected to the cold end structure.

[0012] An enrichment device based on superfluid helium-3 provided by the present invention further includes:

[0013] A total liquid helium tank, which is connected to the first Dewar, and a first valve is provided between the total liquid helium tank and the first Dewar.

[0014] An enrichment device based on superfluid helium-3 provided by the present invention further includes:

[0015] A first vacuum pump and a first monitoring structure, both of which are connected to the first Dewar; the first vacuum pump is used to evacuate the first Dewar, and the first monitoring structure is used to monitor the temperature and pressure of the first Dewar.

[0016] An enrichment device based on superfluid helium-3 provided by the present invention further includes:

[0017] A second Dewar, with the hot end structure arranged inside it, the second Dewar is used to maintain the temperature of the hot end structure, and its top is connected to the total liquid helium tank; and a second valve is provided between the second Dewar and the total liquid helium tank;

[0018] A second vacuum pump and a second monitoring structure, both of which are connected to the second Dewar; the second vacuum pump is used to evacuate the second Dewar, and the second monitoring structure is used to monitor the temperature and pressure of the second Dewar.

[0019] An enrichment device based on superfluid helium-3 provided by the present invention further includes:

[0020] A third Dewar, with the cold end structure arranged inside it, the third Dewar is used to maintain the temperature of the cold end structure, and its top is connected to the total liquid helium tank, and a third valve is provided between the third Dewar and the total liquid helium tank;

[0021] A third vacuum pump and a third monitoring structure, both of which are connected to the third Dewar; the third vacuum pump is used to evacuate the third Dewar, and the third monitoring structure is used to monitor the temperature and pressure of the third Dewar.

[0022] An enrichment device based on superfluid helium-3 provided by the present invention further includes:

[0023] A liquid helium Dewar structure, with the first Dewar, the second Dewar and the third Dewar arranged inside it.

[0024] According to an enrichment device based on superfluid helium-3 provided by the present invention, a fourth valve is provided between the flushing pipe and the first dewar.

[0025] According to an enrichment device based on superfluid helium-3 provided by the present invention, it further includes:

[0026] A pumping device, which is communicated with the cold-end structure, and the pumping device is used to collect the helium-3 and helium-4 normal fluid parts in the superfluid helium.

[0027] The present invention also provides a method for using an enrichment device based on superfluid helium-3, including:

[0028] Releasing the superfluid helium in the first dewar;

[0029] Forming a temperature difference between the hot-end structure and the cold-end structure;

[0030] The helium-4 superfluid part in the superfluid helium flows to the hot-end structure, and the helium-3 and helium-4 normal fluid parts in the superfluid helium flow to the cold-end structure.

[0031] Collecting the helium-4 superfluid part in the superfluid helium at one end of the hot-end structure far from the first dewar, and collecting the helium-3 and helium-4 normal fluid parts in the superfluid helium at one end of the cold-end structure far from the first dewar.

[0032] The enrichment device based on superfluid helium-3 and its using method provided by the present invention store superfluid helium through the first dewar. The hot-end structure and the cold-end structure are both communicated with the first dewar. The temperatures of the first dewar, the hot-end structure and the cold-end structure are all less than 2.17K, so that helium-4 is superfluid helium. According to the two-fluid theory model, a part of the superfluid helium is superfluid and a part is normal fluid. The superfluid transition temperature of helium-3 is 2.6mK, so helium-3 is always a normal fluid during the separation process; the temperature of the hot-end structure is higher than that of the cold-end structure. Under this temperature gradient, the normal fluid and the superfluid flow to both ends. Helium-3 is all in the normal fluid. By using the thermomechanical effect of the superfluid, a device suitable for generating internal convection of superfluid helium is designed, so that the separation degree of the superfluid and the normal fluid is relatively high, achieving the effect of enriching helium-3. Description of the Drawings

[0033] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0034] Figure 1It is a schematic structural diagram of an enrichment device based on superfluid helium-3 provided by the present invention;

[0035] Reference numerals:

[0036] 1. First Dewar; 2. Hot-end structure; 3. Cold-end structure; 4. Flushing pipe; 5. Total liquid helium tank; 6. First valve; 7. Second Dewar; 8. Second valve; 9. Third Dewar; 10. Third valve; 11. Liquid nitrogen Dewar structure; 12. Fourth valve; 13. First pipeline; 14. Second pipeline; 15. Third pipeline; 16. Fourth pipeline; 17. Fifth pipeline; 18. Sixth pipeline; 19. Seventh pipeline; 20. Eighth pipeline; 21. Ninth pipeline; 22. Cold-end pipeline; 23. Hot-end pipeline. Specific embodiments

[0037] In order to make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below with reference to the accompanying drawings in the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without making creative efforts fall within the scope of protection of the present invention.

[0038] In the description of the embodiments of the present invention, it should be noted that the orientation or positional relationships indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the embodiments of the present invention. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and should not be construed as indicating or implying relative importance.

[0039] The following combines Figure 1 Describe an enrichment device based on superfluid helium-3 of the present invention, including a first Dewar 1, a hot-end structure 2 and a cold-end structure 3.

[0040] Among them, the first Dewar 1 is used to store superfluid helium; the hot-end structure 2 and the cold-end structure 3 are both connected to the first Dewar 1; the temperatures of the first Dewar 1, the hot-end structure 2 and the cold-end structure 3 are all less than 2.17 K, so that the liquid helium is in a superfluid helium state. The temperature of the hot-end structure 2 is higher than that of the cold-end structure 3. Under this temperature gradient, the helium-4 superfluid part in the superfluid helium flows to the hot-end structure 2, and the helium-3 and helium-4 normal fluid parts in the superfluid helium flow to the cold-end structure 3.

[0041] The embodiment of the present invention is based on a two-fluid theoretical model, utilizes the thermo-mechanical effect of superfluid helium, sets a hot-end structure 2 and a cold-end structure 3, and there is a temperature gradient between the hot-end structure 2 and the cold-end structure 3, so as to enable superfluid helium to generate an internal convection device, making the separation degree of the superfluid and the normal fluid relatively high, achieving the effect of enriching helium-3.

[0042] Generally speaking, the temperature of the hot-end structure 2 is controlled at about 1.5K, while the temperature of the cold-end structure 3 is controlled at less than 1.5K. At the same time, the temperature of the cold-end structure 3 is always controlled to be less than that of the hot-end structure 2.

[0043] In a feasible embodiment of the present invention, it further includes a flushing pipe 4, which is horizontally arranged so that superfluid helium is not affected by gravity during the hot flushing process. The top is connected to the first dewar 1; and one end of the flushing pipe 4 is connected to the hot-end structure 2, and the other end is connected to the cold-end structure 3. Also, because the flushing pipe 4 is horizontally arranged, the hot-end structure 2 and the cold-end structure 3 are at the same height, that is, there is no height difference between the hot-end structure 2 and the cold-end structure 3. After the temperatures of the hot-end structure 2 and the cold-end structure 3 are stable, the flushing pipe 4 will form a gradient temperature distribution. When the superfluid helium in the first dewar 1 enters the flushing pipe 4, due to the temperature difference at both ends of the flushing pipe 4 and the wall temperature being distributed in a gradient, the superfluid part and the normal fluid part of the superfluid helium flow towards the hot-end structure 2 and the cold-end structure 3 respectively. The helium-3 and helium-4 normal fluids flow out through the cold-end structure 3, and the cold-end structure 3 is connected to a pump to collect the enriched gas. The ratio of helium-3 / helium-4 in the enriched gas can be increased by 10,000 times compared to the original liquid helium; the helium-4 superfluid flows towards the liquid helium recovery device through the hot-end structure 2.

[0044] In a feasible embodiment of the present invention, it further includes a total liquid helium tank 5, and the total liquid helium tank 5 is connected to the first dewar 1. To ensure the safety and convenience of operation of the system, the total liquid helium tank 5 and the first dewar 1 are connected through a first pipeline 13, and a first valve 6 is provided on the first pipeline 13 for opening and closing control.

[0045] In a feasible embodiment of the present invention, a first vacuum pump and a first monitoring structure are further included. The first vacuum pump is connected to the first dewar 1 through a second pipeline 14; the first vacuum pump is used to evacuate the first dewar 1 to ensure that the dewar 1 is maintained below 2.17K, ensuring the stable flow and characteristics of superfluid helium. The first monitoring structure is connected to the first dewar 1 through a third pipeline 15, and the first monitoring structure is used to monitor the temperature and pressure of the first dewar 1 in real time to ensure the system operates under safe and stable conditions. Through the pumping operation of the first vacuum pump, the gas pressure inside the first dewar 1 can be effectively reduced, providing necessary conditions for the flow and characteristics of superfluid helium inside it. At the same time, the real-time monitoring function of the first monitoring structure can promptly detect any abnormal temperature and pressure changes, providing guarantee for the safe operation of the system. Such a design makes the system have higher reliability and safety in the storage, transmission, and processing of superfluid helium.

[0046] In a feasible embodiment of the present invention, a second dewar 7 is further included. A hot end structure 2 is arranged inside the second dewar 7, and the second dewar 7 is used to maintain the temperature of the hot end structure 2, that is, the hot end structure 2 and the second dewar 7 are at the same temperature. The top of the second dewar 7 is connected to the total liquid helium tank 5. To achieve the transmission and regulation of liquid helium, the second dewar 7 and the total liquid helium tank 5 are connected through a fourth pipeline 16, and a second valve 8 is arranged on the fourth pipeline 16. The second valve 8 is used for opening and closing control and can also control the opening degree of the fourth pipeline 16.

[0047] The second dewar 7 is also equipped with a second vacuum pump and a second monitoring structure. The second vacuum pump is connected to the second dewar 7 through a fifth pipeline 17; the second vacuum pump is used to evacuate the second dewar 7 to maintain the stability of its internal environment. The second monitoring structure is connected to the second dewar 7 through a sixth pipeline 18, and the second monitoring structure is used to monitor the temperature and pressure of the second dewar 7 to ensure its operation in a safe and reliable state. The hot end structure 2 is connected to a hot end pipeline 23, and a part of the helium-4 superfluid flows to the hot end structure 2, and the liquid helium is recovered through the hot end pipeline 23.

[0048] In a feasible embodiment of the present invention, it further includes: a third Dewar 9, with a cold end structure 3 disposed inside. The third Dewar 9 is used to maintain the temperature of the cold end structure 3, that is, the third Dewar 9 and the cold end structure 3 are at the same temperature. The top of the third Dewar 9 is connected to the total liquid helium tank 5 through a seventh pipeline 19. In order to achieve the transmission and regulation of liquid helium, a third valve 10 is provided between the third Dewar 9 and the total liquid helium tank 5; a third vacuum pump is connected to the third Dewar 9 through an eighth pipeline 20; the third vacuum pump is used to evacuate the third Dewar 9 to maintain the stability of the internal environment. A third monitoring structure is connected to the third Dewar 9 through a ninth pipeline 21, and is used to monitor the temperature and pressure of the third Dewar 9 to ensure that it operates in a safe and reliable state. The cold end structure 3 is also connected to a cold end pipeline 22. The helium-3 and helium-4 normal fluid parts in the superfluid helium flow to the cold end structure 3 and flow out through the cold end pipeline 22.

[0049] In a feasible embodiment of the present invention, it further includes a liquid nitrogen Dewar structure 11, with a first Dewar 1, a second Dewar 7 and a third Dewar 9 disposed inside, so that the first Dewar 1, the second Dewar 7 and the third Dewar 9 are in a relatively stable low-temperature environment, which can better manage and control their temperatures, and ensure the stable operation of the entire system during the transmission, storage and processing of superfluid helium.

[0050] In a feasible embodiment of the present invention, in order to facilitate operation and avoid misoperation, a fourth valve 12 is provided between the flushing pipe 4 and the first Dewar 1. By opening and closing the fourth valve 12, the fluid flow between the flushing pipe 4 and the first Dewar 1 can be controlled, thereby realizing effective flushing and operation control. Such a design improves the operability and safety of the system.

[0051] In a feasible embodiment of the present invention, it further includes a pumping device, which is connected to the cold end structure 3 through the cold end pipeline 22. The pumping device is used to collect the helium-3 and helium-4 normal fluid parts in the superfluid helium. Through the connection between the pumping device and the cold end structure 3, the pumping device can effectively extract the normal fluid part in the superfluid helium and perform further processing or utilization.

[0052] In addition, the cold end structure 3 can also adopt a non-uniform pipeline, so that the helium-4 superfluid part of the superfluid helium adheres to the pipe wall due to the climbing film effect, reducing the superfluid part flowing into the cold end pipeline and improving the enrichment degree.

[0053] In summary, for the enrichment device based on superfluid helium-3 provided in the first aspect embodiment of the present invention, first, the liquid nitrogen dewar structure 11 is evacuated. The second pipeline 14, the fifth pipeline 17, and the eighth pipeline 20 are respectively connected to the first vacuum pump, the second vacuum pump, and the third vacuum pump. The first valve 6, the second valve 8, and the third valve 10 are opened, and the fourth valve 12 is closed. The third pipeline 15, the sixth pipeline 18, and the ninth pipeline 21 are respectively connected to the first monitoring structure, the second monitoring structure, and the third monitoring structure for detecting temperature and pressure. The first dewar 1, the second dewar 7, and the third dewar 9 are cooled to the working temperature and maintained. Among them, the first dewar 1 is maintained slightly below 2.17K, the second dewar 7 is maintained at about 1.5K, and the third dewar 9 is maintained below 1.5K. The flushing pipe 4 is made of a metal material with relatively good thermal conductivity, such as a copper pipe. After the temperatures of the second dewar 7 and the third dewar 9 are stabilized, a gradient temperature distribution will be formed in the flushing pipe 4. Then, the fourth valve 12 is slowly opened, so that the superfluid helium in the first dewar 1 enters the flushing pipe 4. Due to the temperature difference at both ends of the flushing pipe and the gradient distribution of the wall temperature, the superfluid component and the normal fluid component of the superfluid helium will flow to the hot end structure 2 and the cold end structure 3 respectively. The helium-3 and helium-4 normal fluids flow out from the cold end pipe 22 through the cold end structure 3. The cold end pipe 22 is connected to a pumping device to collect the enriched gas. The ratio of helium-3 / helium-4 in the enriched gas can be increased by 10,000 times compared with the original liquid helium; the helium-4 superfluid flows to the liquid helium recovery device through the hot end pipe 23.

[0054] The second aspect embodiment of the present invention lies in providing a method for using an enrichment device based on superfluid helium-3. Using the enrichment device based on superfluid helium-3 as described in the above embodiment, it includes:

[0055] S1. Release the superfluid helium in the first dewar 1;

[0056] S2. Form a temperature difference between the hot end structure 2 and the cold end structure 3;

[0057] S3. The helium-4 superfluid part in the superfluid helium flows to the hot end structure 2, and the helium-3 and helium-4 normal fluid parts in the superfluid helium flow to the cold end structure 3.

[0058] S4. Collect the helium-4 superfluid part in the superfluid helium at one end of the hot end structure 2 far from the first dewar 1, and collect the helium-3 and helium-4 normal fluid parts in the superfluid helium at one end of the cold end structure 3 far from the first dewar 1.

[0059] For the method for using an enrichment device based on superfluid helium-3 provided in the second aspect embodiment of the present invention, by adjusting the temperatures of the hot end structure 2 and the cold end structure 3, the temperature distribution in the flushing pipe 4 is more uniform, and a better flushing effect will be produced.

[0060] In summary, the present invention controls the temperature of the hot-end structure 2 by using the second Dewar 7, and controls the temperature of the cold-end structure by using the third Dewar 9. That is, by controlling both ends of the flushing pipe with Dewars at different temperatures, the superfluid helium entering the flushing pipe 4 can undergo sufficient internal convection. The continuous working process can greatly save time costs and improve the separation rate.

[0061] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0062] In the description of this specification, the descriptions with reference to terms such as "one embodiment", "some embodiments", "mode", "specific mode", or "some modes" mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or mode are included in at least one embodiment or mode of the embodiments of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or mode. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or modes. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or modes described in this specification and the features of different embodiments or modes.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An enrichment device based on superfluid helium-3, characterized in that, Comprising: A first Dewar (1) for storing superfluid helium; A hot end structure (2) and a cold end structure (3), both communicating with the first Dewar (1); The temperatures of the first Dewar (1), the hot end structure (2) and the cold end structure (3) are all less than 2.17K, and the temperature of the hot end structure (2) is greater than the temperature of the cold end structure (3); The helium-4 superfluid part in the superfluid helium flows to the hot end structure (2), and the helium-3 and helium-4 normal fluid parts in the superfluid helium flow to the cold end structure (3).

2. The enrichment device based on superfluid helium-3 according to claim 1, wherein Also included is a flushing pipe (4), horizontally arranged, with its top communicating with the first Dewar (1); and one end of the flushing pipe (4) communicates with the hot end structure (2), and the other end communicates with the cold end structure (3).

3. The enrichment device based on superfluid helium-3 according to claim 1, wherein Also comprising: A total liquid helium tank (5), communicating with the first Dewar (1), and a first valve (6) is provided between the total liquid helium tank (5) and the first Dewar (1).

4. The enrichment device based on superfluid helium-3 according to claim 1, characterized in that, Also comprising: A first vacuum pump and a first monitoring structure, both communicating with the first Dewar (1); the first vacuum pump is used to evacuate the first Dewar (1), and the first monitoring structure is used to monitor the temperature and pressure of the first Dewar (1).

5. The enrichment device based on superfluid helium-3 according to claim 3, characterized in that, Also comprising: A second Dewar (7) with the hot end structure (2) arranged inside, the second Dewar (7) is used to maintain the temperature of the hot end structure (2), and its top communicates with the total liquid helium tank (5); and a second valve (8) is provided between the second Dewar (7) and the total liquid helium tank (5); A second vacuum pump and a second monitoring structure, both communicating with the second Dewar (7); the second vacuum pump is used to evacuate the second Dewar (7), and the second monitoring structure is used to monitor the temperature and pressure of the second Dewar (7).

6. The enrichment device based on superfluid helium-3 according to claim 5, characterized in that, Also comprising: A third Dewar (9) with the cold end structure (3) arranged inside, the third Dewar (9) is used to maintain the temperature of the cold end structure (3), and its top communicates with the total liquid helium tank (5), and a third valve (10) is provided between the third Dewar (9) and the total liquid helium tank (5); A third vacuum pump and a third monitoring structure, both communicating with the third Dewar (9); the third vacuum pump is used to evacuate the third Dewar (9), and the third monitoring structure is used to monitor the temperature and pressure of the third Dewar (9).

7. The enrichment device based on superfluid helium-3 according to claim 6, characterized in that Also comprising: A liquid nitrogen Dewar structure (11) with the first Dewar (1), the second Dewar (7) and the third Dewar (9) arranged inside.

8. The enrichment device based on superfluid helium-3 according to claim 2, wherein A fourth valve (12) is provided between the flushing pipe (4) and the first Dewar (1).

9. The enrichment device based on superfluid helium-3 according to claim 2, characterized in that, Also comprising: A pumping device, communicating with the cold end structure (3), and the pumping device is used to collect the helium-3 and helium-4 normal fluid parts in the superfluid helium.

10. A method for using an enrichment device based on superfluid helium-3, which utilizes the enrichment device based on superfluid helium-3 as described in any one of claims 1-9, characterized in that, Comprising: Releasing the superfluid helium in the first Dewar (1); Forming a temperature difference between the hot end structure (2) and the cold end structure (3); The helium-4 superfluid part in the superfluid helium flows to the hot end structure (2), and the helium-3 and helium-4 normal fluid parts in the superfluid helium flow to the cold end structure (3). Collect the helium-4 superfluid part in the superfluid helium at one end of the hot end structure (2) far from the first dewar (1), and collect the helium-3 and helium-4 normal fluid parts in the superfluid helium at one end of the cold end structure (3) far from the first dewar (1).

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