Double corrugated tube low heat leakage dewar and fast sample changing measuring device

Abstract

This invention discloses a low-heat-leakage Dewar and rapid sample-changing testing device with dual corrugated tubes, comprising a vacuum chamber, a refrigeration system, and a sample chamber. The vacuum chamber includes a first top cover, a first flange, a second flange, a first cylinder, and a first tailpipe. The first and second flanges are located on either side of the centerline of the first top cover. The refrigeration system includes a refrigerator, a second top cover, a second cylinder, a second tailpipe, and a secondary cold head heat-conducting plate. The secondary cold head of the refrigerator is fixedly connected to the secondary cold head heat-conducting plate. The sample chamber includes a first corrugated tube, a second corrugated tube, and a third tailpipe. One end of the first corrugated tube is fixed to the first flange, and the other end is fixed to the second top cover. One end of the second corrugated tube is fixed to the second top cover, and the other end, along with the third tailpipe, is fixed to the upper and lower sides of the secondary cold head heat-conducting plate, respectively. The first, second, and third corrugated tubes are coaxial and coaxially assembled from the outside to the inside. Advantages of this invention: significantly reduced heat leakage, compact and stable structure, and reduced cost.

Description

Technical Field

[0001] This invention belongs to the field of cryogenic equipment and measurement technology, specifically a double-corrugated tube low-heat-leakage Dewar and rapid sample-changing measurement device. Background Technology

[0002] Liquid helium immersion cooling offers advantages such as good stability, low vibration, and high cooling capacity. However, helium is a non-renewable resource, and with its designation as a strategic material and restrictions on its extraction, the price of liquid helium has increased dramatically, making its use costly. Furthermore, the use of liquid helium generally requires a complete and expensive recovery, purification, and liquefaction system, which needs to be maintained by dedicated technicians, and the existence of recovery pipelines further limits its application.

[0003] The numerous limitations of using liquid helium have spurred the development of cryogenic Dewars equipped with small refrigerators as cold sources, which have been widely adopted in recent years. However, small refrigerators have low cooling power in the liquid helium temperature range, making them difficult to integrate with large-aperture sample chamber designs that have high heat loads. For example, in CN116146885A, the cooling of the large-aperture sample chamber relies on liquid helium immersion, resulting in significant liquid helium loss. While using high-powered refrigerators or multiple small refrigerators can solve the cooling problem of large-aperture sample chambers, this would greatly increase the system size, cost, and complexity.

[0004] Using corrugated pipes as heat conduction channels in the room temperature and low temperature regions can increase the solid heat transfer path while reducing the heat transfer area, significantly reducing heat leakage from the sample cavity. For example, CN116007792A discloses a low-temperature calibration system for the superfluid helium temperature region under a magnetic field environment. This system includes a low-temperature Dewar, a low-temperature isothermal system, a sample cavity, a superconducting magnet system, and low-temperature measurement and control equipment. The low-temperature Dewar consists of an outer vacuum cavity assembly and a radiation-shielding cold shield assembly located within the vacuum cavity. The vacuum cavity comprises a top cover, a cylinder, and a vacuum unit providing negative pressure; the cold shield is suspended within the cylinder. The sample cavity consists of a cavity body and a sample rod, with the sample cavity installed at the center of the top cover, extending downwards to the center of the vacuum cavity. A heater is located at the bottom, and the sample rod is inserted into the sample cavity, with a sample holder at the bottom. The low-temperature isothermal system consists of two GM refrigerators, installed on both sides of the sample cavity, with the main body extending into the vacuum cavity. The superconducting magnet system is suspended around the sample holder. The structure uses two refrigerators, which is complex. In addition, its bellows has no support structure. Changes in the vacuum level in the sample chamber will cause the sample chamber to expand and contract significantly in the vertical direction and swing laterally, which poses a safety hazard and may also damage the Dewar device and the test device in the sample chamber. Summary of the Invention

[0005] The technical problem to be solved by this invention is how to solve the problems of unstable structure and high cost of existing rapid sample change measurement devices.

[0006] The present invention solves the above-mentioned technical problems through the following technical means:

[0007] A low-heat-leakage Dewar with double bellows includes a vacuum chamber, a cooling system, and a sample chamber.

[0008] The vacuum chamber includes a first top cover, a first flange, a second flange, a first cylinder, and a first tail pipe; the first top cover, the first cylinder, and the first tail pipe are sequentially fixed to form the vacuum chamber; the first flange and the second flange seal the two inlets opened in the first top cover;

[0009] The refrigeration system includes a refrigeration unit, a second top cover, a second cylinder, a second tailpipe, and a secondary cold head cooling plate. The main body of the refrigeration unit is placed inside the first cylinder. The primary cold head of the refrigeration unit is fixed to the second top cover, and the secondary cold head of the refrigeration unit is fixedly connected to the secondary cold head cooling plate.

[0010] The sample chamber includes a first corrugated tube, a second corrugated tube, and a third tail tube. One end of the first corrugated tube is fixed to a first flange, and the other end is fixed to a second top cover. One end of the second corrugated tube is fixed to the second top cover, and the other end and the third tail tube are respectively fixed to the upper and lower sides of the secondary cold head cooling plate. The first corrugated tube, the second corrugated tube, and the third tail tube are coaxially connected.

[0011] The first tailpipe is installed at the bottom of the first cylinder, and the second tailpipe is installed at the bottom of the second cylinder. The first tailpipe, the second tailpipe, and the third tailpipe are coaxially assembled from the outside to the inside.

[0012] The double-corrugated sample chamber used in this invention significantly reduces heat leakage while ensuring structural stability, compared with the existing thin-walled neck tube structure. This invention uses a refrigerator as a cold source, eliminating the need for liquid helium and significantly reducing operating costs.

[0013] Furthermore, it also includes a support assembly, which includes a first support and a second support. The first support is supported between the first top cover and the second top cover, and the first support is located on both sides of the connection between the first corrugated pipe and the refrigerator. One end of the second support is fixed to the second top cover, and the other end is fixedly connected to the secondary cold head cold guide plate. The second support is coaxial with the second corrugated pipe.

[0014] Furthermore, a heating circuit is wound around the third tail tube, which consists of a heating wire and a thermometer.

[0015] Furthermore, the first top cover is equipped with an electrical interface, a safety valve, and a first vacuum extraction port.

[0016] Furthermore, the first flange is provided with reinforcing ribs and a second vacuum extraction port.

[0017] Furthermore, activated carbon packets are provided at the bottom of the secondary cold head heat-conducting plate, the second tail pipe, and the third tail pipe.

[0018] Furthermore, anti-collision supports are provided on both the bottom end cap of the second tailpipe and the bottom end cap of the third tailpipe.

[0019] Furthermore, the anti-collision support is fixed to the bottom end caps of the second and third tail tubes respectively by bolts, and the two sides of the anti-collision support are in contact with the inner walls of the second and first tail tubes respectively.

[0020] The present invention also provides a rapid sample change measurement system using the above-mentioned double-corrugated low-heat-leakage Dewar.

[0021] Furthermore, it also includes a vacuum adapter, a gate valve, and a one-dimensional hollow linear introducer. The built-in frame is installed inside the one-dimensional hollow linear introducer. The vacuum adapter, gate valve, and one-dimensional hollow linear introducer are coaxially mounted on the first flange from bottom to top. The built-in frame extends completely into the sample chamber after the one-dimensional hollow linear introducer is compressed.

[0022] The advantages of this invention are:

[0023] (1) The double-corrugated sample chamber used in this invention significantly reduces heat leakage while ensuring structural stability compared with the existing thin-walled neck tube structure; the invention uses a refrigerator as a cold source, eliminating the need for liquid helium and significantly reducing operating costs.

[0024] (2) The support assembly ensures the stability of the two bellows; the support assembly also serves as a weight support for the internal structure. The internal structure includes: a cold shield assembly, a second top cover, a second cylinder, a second tail tube; a secondary cold head cooling plate, and a third tail tube for the sample chamber. This increases the rigidity of the system structure and reduces the low-temperature displacement of the second and third tail tubes.

[0025] (3) This invention achieves compatibility between a small refrigerator and a sample chamber with a large aperture range, with a simple and compact structure, improving system reliability; the compatibility is specifically reflected in:

[0026] The sample chamber employs a segmented structural design, comprising a first corrugated tube, a second corrugated tube, and a third tail tube coaxially connected. The upper end of the first corrugated tube is at room temperature, while the lower end is thermally connected to the first-stage cold head via a second top cover, anchoring the temperature at 50K. For a 0mm diameter sample chamber, approximately 0.3W of heat is conducted to the first-stage cold head. The upper end of the second corrugated tube is thermally connected to the first-stage cold head via a second top cover, anchoring the temperature at 50K. The lower end is thermally connected to the second-stage cold head via a cooling plate, resulting in approximately 0.06W of heat conduction to the second-stage cold head for a 0mm diameter sample chamber. This structure requires only a low-power refrigerator with a first-stage cold head heat load of approximately 20W and a second-stage cold head heat load of approximately 0.5W. If a single straight tube design were used for the sample chamber, with the same diameter and length, the second-stage cold head heat leakage would be 1.5W, requiring two 1W@4.2K refrigerators or one 2.0W@4.2K refrigerator to meet the cooling requirements. This structure, through its segmented sample chamber design, reduces heat leakage by a significant amount compared to a single straight tube design, and achieves compatibility with small refrigerators and sample chambers with a wide range of diameters.

[0027] (4) The dual-corrugated tube low-leakage Dewar and rapid sample change system in this invention are suitable for sample measurement systems with a large aperture range under different extreme conditions, and can achieve rapid sample change. This design can be implanted in a strong magnetic field environment (e.g., a room temperature magnet with an inner diameter of 150 mm), realizing the combination of low temperature and strong magnetic field extreme environments. In addition, the introduction of a large-aperture sample cavity makes it easier to introduce other extreme measurement conditions such as terahertz lasers. Attached Figure Description

[0028] Figure 1 This is an overall structural diagram of a double-corrugated pipe low-heat-leakage Dewar according to Embodiment 1 of the present invention;

[0029] Figure 2 These are the left and rear views of a double-corrugated pipe low-heat-leakage Dewar according to Embodiment 1 of the present invention;

[0030] Figure 3 This is a top view of a double-corrugated pipe low-heat-leakage Dewar according to Embodiment 1 of the present invention;

[0031] Figure 4 This is a cross-sectional view of a double-corrugated pipe low-heat-leakage Dewar according to Embodiment 1 of the present invention;

[0032] Figure 5 yes Figure 4 A magnified view of the upper middle section;

[0033] Figure 6 yes Figure 4 Enlarged view of point B in the middle;

[0034] Figure 7 yes Figure 2 Internal structure diagram of the middle and rear view;

[0035] Figure 8 This is an overall structural diagram of the rapid sample change measurement system of Embodiment 2 of the present invention.

[0036] Numbered in the diagram: 1. First top cover; 2. First cylinder; 3. First tailpipe; 4. First flange; 5. Second flange; 6. Refrigeration unit; 61. First-stage cold head; 62. Second-stage cold head; 7. Second top cover; 8. Second cylinder; 9. Second tailpipe; 10. Second-stage cold head cooling plate; 11. First corrugated pipe; 12. Second corrugated pipe; 13. Third tailpipe; 14. First support; 15. Second support; 16. Heating wire; 17. Electrical interface; 18. Safety valve; 19. First vacuum extraction port; 20. Reinforcing rib; 21. Second vacuum extraction port; 22. Activated carbon bag; 23. Anti-collision wall support; 24. Vacuum adapter; 25. Gate valve; 26. One-dimensional hollow linear inlet; 27. Internal frame. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Example 1

[0039] like Figure 1 , 2As shown, a low-leakage Dewar with double corrugated pipes includes a vacuum chamber, a refrigeration system, and a sample chamber. The vacuum chamber includes a first top cover 1, a first flange 4, a second flange 5, a first cylinder 2, and a first tail pipe 3. The first flange 4 and the second flange 5 are located on opposite sides of the centerline of the first top cover 1. The refrigeration system includes a refrigerator 6, a second top cover 7, a second cylinder 8, a second tail pipe 9, and a secondary cold head heat-conducting plate 10. The refrigerator 6 is installed on the second flange 4, and the main body of the refrigerator is placed inside the first cylinder 2. The primary cold head 61 of the refrigerator is fixed to the second top cover 7, and the secondary cold head 62 of the refrigerator is fixedly connected to the secondary cold head heat-conducting plate 10. The sample chamber includes a first corrugated tube 11, a second corrugated tube 12, and a third tail tube 13. One end of the first corrugated tube 11 is fixed to the first flange 4, and the other end is fixed to the second top cover 7. One end of the second corrugated tube 12 is fixed to the second top cover 7, and the other end and the third tail tube 13 are respectively fixed to the upper and lower sides of the secondary cold head cooling plate 10. The first corrugated tube 11, the second corrugated tube 12, and the third tail tube 13 are coaxial. The first tail tube 3 is installed at the bottom of the first cylinder 2, and the second tail tube 9 is installed at the bottom of the second cylinder 8 through a flange. The first tail tube 3, the second tail tube 9, and the third tail tube 13 are coaxially assembled from the outside to the inside. Compared with the existing thin-walled neck tube structure, the double corrugated tube sample chamber used in this embodiment significantly reduces heat leakage while ensuring structural stability. In this embodiment, the corrugated tubes are made of 304 stainless steel. The corrugated tubes are welded and fixed to other components. Vacuum brazing (silver-based solder) is used for parts requiring high thermal conductivity to ensure sealing.

[0040] like Figure 7 As shown, the support assembly includes a first support 14 and a second support 15. One end of the first support 14 is fixed to the first top cover 1, and the other end is fixed to the second top cover 7. The first support 14 is located on both sides of the line connecting the first corrugated pipe 11 and the refrigerator 6. One end of the second support 15 is fixed to the second top cover 7, and the other end is bolted to the secondary cold head cooling plate 10. The second support 15 is coaxial with the second corrugated pipe 12. The support assembly ensures the stability of the two corrugated pipes. In this embodiment, the second support 15 is cylindrical, which has good strength and can withstand the pressure generated by changes in vacuum level within the vacuum chamber. It is also easy to process and install. Of course, it can also be a rectangular cylinder.

[0041] like Figure 7 As shown, a heating circuit is wound around the third tail tube 13. The heating circuit consists of a heating wire 16 and a thermometer. The continuous temperature variation of the sample chamber tail tube 13 is achieved through thermal compensation.

[0042] like Figure 3 As shown, the first top cover 1 is equipped with an electrical interface 17, a safety valve 18 and a first vacuum port 19, which is used to evacuate the vacuum chamber.

[0043] like Figure 3 As shown, a reinforcing rib 20 and a second vacuum port 21 are installed on the first flange 4. The second vacuum port 21 is used to evacuate the cavity formed by the first bellows 11, the second bellows 12 and the third tail pipe 13.

[0044] like Figure 6 As shown, activated carbon bags 22 are installed on the cooling plate 10 of the secondary cold head, the bottom end cap of the second tail pipe 9, and the bottom end cap of the third tail pipe 13. The activated carbon bags are tightly pressed to the fixed surface by bolts. The carbon bags have strong adsorption capacity at low temperatures and can adsorb gases such as hydrogen and helium that are difficult to be evacuated by the vacuum pump, thereby improving the Dewar vacuum level and further reducing heat leakage.

[0045] like Figure 6 As shown, anti-collision supports 23 are installed on the bottom end caps of the second tailpipe 9 and the third tailpipe 13. The anti-collision supports 23 are generally ring-shaped brackets made of fiberglass and are fixed to the bottom end caps of the second tailpipe 9 and the third tailpipe 13 respectively by bolts. The two sides of the anti-collision supports 23 are in contact with the inner walls of the second tailpipe 9 and the first tailpipe 3 respectively.

[0046] Example 2

[0047] This embodiment describes the rapid sample change measurement system using the Dewar of Embodiment 1, and also includes an internal frame 27, which includes a radiation shield and a sample measurement device. It also includes a vacuum adapter 24, a gate valve 25, and a one-dimensional hollow linear inlet 26, which are coaxially mounted on the first flange 4 from bottom to top.

[0048] In this embodiment, the gate valve 25 is first closed, helium gas is introduced into the one-dimensional hollow linear introducer 26 and maintained at positive pressure, the sample measuring device is inserted, and then the one-dimensional hollow linear introducer 26 is flushed three times. The gate valve is then opened, and the sample measuring device is introduced into the Dewar through the one-dimensional hollow linear introducer 26 for temperature-controlled measurement. When removing the device, helium gas is introduced into the sample chamber vacuum port 21 and maintained at positive pressure. The sample measuring device is lifted out of the Dewar through the one-dimensional hollow linear introducer 26, then the gate valve 25 is closed, and the sample chamber is evacuated. Helium exchange gas is introduced into the one-dimensional hollow linear introducer 26, and the measuring device is removed after the sample reaches room temperature.

[0049] In this embodiment, the vacuum chamber and cold shield are first evacuated to a vacuum state. Then, the refrigerator is turned on and operates until the temperature of the secondary cold head reaches approximately 30K. The vacuum port of the vacuum chamber is then closed, and the temperature continues to decrease until it stabilizes. The heating circuit is then turned on to heat the sample chamber to 300K. Helium gas is introduced through the second vacuum port to maintain a positive pressure in the sample chamber. The internal frame 27 is then placed in the sample chamber, and the sample chamber is flushed with helium three times. The heating circuit is then turned off. Exchange gas is introduced to cool the sample measuring device. Once the temperature stabilizes, the test is performed. After the test is completed, the heating circuit is turned on to heat the sample chamber to 300K. Helium gas is introduced through the vacuum port of the sample chamber to maintain a positive pressure in the sample chamber. The internal frame is then removed.

[0050] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A Dewar with low heat leakage and double corrugated pipes, characterized in that, Includes a vacuum chamber, a cooling system, and a sample chamber. The vacuum chamber includes a first top cover (1), a first flange (4), a second flange (5), a first cylinder (2), and a first tail pipe (3); the first top cover (1), the first cylinder (2), and the first tail pipe (3) are fixed in sequence to form the vacuum chamber; the first flange (4) and the second flange (5) block the two inlets opened on the first top cover (1); The refrigeration system includes a refrigeration unit (6), a second top cover (7), a second cylinder (8), a second tail pipe (9), and a secondary cold head guide plate (10). The main body of the refrigeration unit (6) is placed inside the first cylinder (2). The primary cold head (61) of the refrigeration unit (6) is fixed to the second top cover (7), and the secondary cold head (62) of the refrigeration unit (6) is fixedly connected to the secondary cold head guide plate (10). The sample chamber includes a first corrugated pipe (11), a second corrugated pipe (12), and a third tail pipe (13). One end of the first corrugated pipe (11) is fixed to the first flange (4), and the other end is fixed to the second top cover (7). One end of the second corrugated pipe (12) is fixed to the second top cover (7), and the other end and the third tail pipe (13) are respectively fixed to the upper and lower sides of the secondary cold head cooling plate (10). The first corrugated pipe (11), the second corrugated pipe (12), and the third tail pipe (13) are coaxially connected. The first tailpipe (3) is installed at the bottom of the first cylinder (2), and the second tailpipe (9) is installed at the bottom of the second cylinder (8). The first tailpipe (3), the second tailpipe (9) and the third tailpipe (13) are coaxially mounted from the outside to the inside.

2. The Dewar with low heat leakage and double corrugated pipe according to claim 1, characterized in that, It also includes a support assembly, which includes a first support (14) and a second support (15). The first support (14) is supported between the first top cover (1) and the second top cover (7). The first support (14) is located on both sides of the line connecting the first corrugated pipe (11) and the refrigerator (6). One end of the second support (15) is fixed to the second top cover (7), and the other end is fixedly connected to the secondary cold head cold guide plate (10). The second support (15) is coaxial with the second corrugated pipe (12).

3. The Dewar with low heat leakage and double corrugated pipe according to claim 1, characterized in that, The third tail tube (13) is wound with a heating circuit, which consists of a heating wire (16) and a thermometer.

4. A Dewar with low heat leakage due to double corrugated pipes according to claim 1, characterized in that, The first top cover (1) is provided with an electrical interface (17), a safety valve (18) and a first vacuum port (19).

5. A Dewar with low heat leakage due to double corrugated pipes according to claim 1, characterized in that, The first flange (4) is provided with reinforcing ribs (20) and a second vacuum extraction port (21).

6. A Dewar with low heat leakage and double corrugated pipes according to claim 1, characterized in that, The bottom of the heat-conducting plate (10) of the secondary cold head (62), the second tail pipe (9) and the third tail pipe (13) are all provided with activated carbon packs (22).

7. A Dewar with low heat leakage and double corrugated pipes according to claim 1, characterized in that, Anti-collision support (23) is provided on the bottom end cap of the second tail tube (9) and the bottom end cap of the third tail tube (13).

8. A Dewar with low heat leakage and double corrugated pipes according to claim 7, characterized in that, The anti-collision support (23) is fixed to the bottom end caps of the second tail tube (9) and the third tail tube (13) respectively by bolts. The two sides of the anti-collision support (23) are in contact with the inner walls of the second tail tube (9) and the first tail tube (3) respectively.

9. A rapid sample change measurement system made from a double-corrugated low-heat-leakage Dewar as described in any one of claims 1 to 8.

10. A rapid sample change measurement system according to claim 9, characterized in that, It also includes a vacuum adapter (24), a gate valve (25) and a one-dimensional hollow linear inlet (26). The built-in frame (27) is installed inside the one-dimensional hollow linear inlet (26). The vacuum adapter (24), the gate valve (25) and the one-dimensional hollow linear inlet (26) are coaxially mounted on the first flange (4) from bottom to top. The built-in frame (27) extends completely into the sample chamber after the one-dimensional hollow linear inlet (26) is compressed.

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