A cryogenic system based on GM refrigerator to achieve ultra-low vibration below 2K

Abstract

The present invention discloses a cryogenic system for achieving ultra-low vibration below 2K based on a GM refrigerator, comprising a target vibration reduction cold screen (7), a secondary cold screen (6), a primary cold screen (5) and a vacuum chamber (4), wherein the target vibration reduction cold screen (7) is independently fixed on a target vibration reduction cold screen independent bracket (2), and the vacuum chamber (4) is independently suspended on a vacuum chamber independent bracket (3), and the target vibration reduction cold screen independent bracket (2) and the vacuum chamber independent bracket (3) without direct contact are fixedly arranged on a vibration-free ground (1); the secondary cold screen (6) is independently fixed on the primary cold screen (5) and the primary cold screen (5) is independently fixed on the vacuum chamber (4), and the connection between each component and the secondary cold screen (6) and the primary cold screen (5) is softly connected by oxygen-free copper braid (11); the GM refrigerator (13) is connected to the vacuum chamber (4) through a GM refrigerator vibration reduction bellows (16). The cryogenic system of the present invention can reduce vibration and improve performance.

Description

Technical Field

[0001] The invention belongs to the field of refrigeration and cryogenic engineering, and specifically is a cryogenic system based on a GM refrigerator to achieve ultra-low vibration below 2K. Background Art

[0002] With the continuous development and innovation of science and technology, extreme environment detection technology plays a very important role in the ever-changing scientific research work. Among them, low temperature environment, as an important experimental means, plays an irreplaceable role in practical basic scientific research and industrial application. Common methods to achieve temperatures below 2K include JT throttling, He3 refrigerator and dilution refrigerator. Due to the shortage of helium resources on the earth, using GM refrigerator or pulse tube refrigerator as a cold source to achieve a completely closed cycle working mode can effectively save helium resources. GM refrigerator has attracted much attention due to its large refrigeration power and more convenient actual operation and maintenance. Due to the limitations of the working principle of GM refrigerator itself, GM refrigerator inevitably introduces large vibration during operation. When using GM refrigerator as the basis to build a dilution refrigerator or a low-temperature system below 2K, it is necessary to consider the vibration reduction problem. In order to solve the impact of the large vibration of GM refrigerator on the low-temperature system below 2K, a low-temperature system based on GM refrigerator to achieve ultra-low vibration below 2K is proposed. Summary of the invention

[0003] The purpose of the present invention is to provide a cryogenic system based on a GM refrigerator to achieve ultra-low vibration below 2K in order to minimize the vibration of the cryogenic system and improve the performance of the cryogenic system in order to solve the problems existing in the prior art.

[0004] The purpose of the present invention is to be solved by the following technical solutions:

[0005] A cryogenic system based on a GM refrigerator to achieve ultra-low vibration below 2K, characterized in that: the cryogenic system comprises a target vibration reduction cold screen and a secondary cold screen, a primary cold screen and a vacuum chamber which are sequentially sleeved on the outside of the target vibration reduction cold screen, and the four are coaxially arranged, the target vibration reduction cold screen is independently fixed to a target vibration reduction cold screen independent bracket through a target vibration reduction cold screen support rod, the vacuum chamber is independently suspended on a vacuum chamber independent bracket arranged in an inner cavity formed by the target vibration reduction cold screen independent bracket, the target vibration reduction cold screen independent bracket and the vacuum chamber independent bracket are both fixedly arranged on a vibration-free ground and there is no gap between the two. Direct contact; the secondary cold screen is fixed on the coaxially arranged primary cold screen through an independent support rod, and the primary cold screen is fixed on the upper cover of the coaxially arranged vacuum chamber through an independent support rod, and the connection between the support rod and the target vibration reduction cold screen support rod and the secondary cold screen and the primary cold screen adopts oxygen-free copper braid as low-temperature cold sink for soft connection; in order to avoid the influence of the vibration of the GM refrigerator on the vacuum chamber, the GM refrigerator and the vacuum chamber are transitionally connected by welding the GM refrigerator vibration reduction bellows, and the GM refrigerator is independently suspended, so as to avoid the influence of the vibration of the GM refrigerator on the vacuum chamber.

[0006] A vibration damper is provided on the independent bracket of the target vibration damping cold screen to improve the vibration damping effect of the overall system; a suspension part for suspending the target vibration damping cold screen is provided on the vibration damper, and a fine-tuning mechanism capable of adjusting the position of the target vibration damping cold screen is provided on the suspension part to ensure the concentricity of the target vibration damping cold screen with the secondary cold screen and the primary cold screen.

[0007] The vacuum chamber independent support is provided with a vibration damper to improve the vibration reduction effect of the overall system; the upper cover of the vacuum chamber is pressed on the vibration damper so that the vacuum chamber is independently suspended on the vacuum chamber independent support.

[0008] The above-mentioned shock absorber is an air-floating shock absorber, a rubber shock absorber or other active shock absorbers.

[0009] The target vibration reduction cold screen support rod and the vacuum chamber are connected by a target vibration reduction cold screen vibration reduction bellows, which can effectively isolate the vacuum chamber from the vibration of the target vibration reduction cold screen support rod.

[0010] In order to reduce the heat leakage of the target vibration reduction cold screen independent support, the target vibration reduction cold screen support rod adopts thin-walled stainless steel pipe (larger diameter) or G10 rod, which reduces heat leakage and increases the strength of longitudinal tension and transverse shear force.

[0011] Furthermore, in order to reduce the heat leakage of the thin-walled tube to the part below the target vibration reduction cold screen, oxygen-free copper braids are used to perform low-temperature cooling at the primary cold screen and the secondary cold screen, respectively, to reduce heat leakage while reducing the impact of each cold screen on the thin-walled tube.

[0012] A disconnectable mechanical thermal switch is provided between the target vibration reduction cold screen and the secondary cold screen. The closing surface of the mechanical thermal switch is a parallel plane or a conical surface, and oxygen-free copper braid is used to achieve a certain distance travel.

[0013] In order to ensure low vibration of the primary and secondary cold screens, oxygen-free copper braids are used as low-temperature cold sinks at the primary and secondary cold heads of the GM refrigerator to softly connect the primary and secondary cold screens, reducing the impact of the cold head vibration on the cold screens; in order to reduce the impact of the primary and secondary cold screens on the pipelines, oxygen-free copper braids are used as low-temperature cold sinks at the connections between the primary and secondary cold screens and the pumping pipelines for soft connection, reducing the vibration of the pumping pipelines.

[0014] The evacuation pipeline is connected to the vacuum chamber through the evacuation pipeline vibration reduction bellows, which reduces the influence of the vacuum pump group on the evacuation pipeline inside the vacuum chamber; the evacuation pipeline is connected to the distillation chamber (Still) through the evacuation pipeline transition bellows, which reduces the installation stress and the influence of the evacuation pipeline on the part below the target vibration reduction cold screen.

[0015] The first-stage cold head and the second-stage cold head of the GM refrigerator respectively use oxygen-free copper braids as low-temperature cold sinks to flexibly connect the intake heat exchanger to reduce the impact of the cold head vibration on the intake pipeline, thereby reducing the impact on the part below the target vibration reduction cold screen.

[0016] The flow resistance, distillation chamber (Still), target vibration reduction cold screen, continuous heat exchanger, step heat exchanger and mixing chamber are packaged together as an accessory and are independently fixed on the target vibration reduction cold screen independent bracket through the target vibration reduction cold screen support rod.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] The present invention solves the vibration problem of realizing a low-temperature system below 2K based on the GM refrigerator by arranging an independent support of the target low-temperature cold screen to isolate it from direct contact with the GM refrigerator.

[0019] The present invention adopts oxygen-free copper braids to softly connect the cold screens, thereby increasing cooling conduction and reducing the influence of the vibration of the cold head on the cold screens.

[0020] The present invention adopts a mechanical heat switch to achieve rapid cooling, and after the heat switch is disconnected, the connection with the target vibration reduction cold screen can be completely disconnected.

[0021] The present invention connects the target vibration reduction cold screen support rod with the upper cover flange portion of the vacuum chamber and adopts a welded target vibration reduction cold screen vibration reduction bellows as a transition connection pipe. The welded bellows is relatively soft and can effectively isolate the transmission of vibration. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Attached Figure 1A schematic diagram of an independent support structure of a cryogenic system of the present invention;

[0023] Attached Figure 2 It is a schematic diagram of the internal supporting shock absorbing structure of the low temperature system of the present invention.

[0024] Among them: 1—vibration-free ground; 2—target vibration-reducing cold screen independent bracket; 3—vacuum chamber independent bracket; 4—vacuum chamber; 5—primary cold screen; 6—secondary cold screen; 7—target vibration-reducing cold screen; 8—target vibration-reducing cold screen vibration-reducing bellows; 9—target vibration-reducing cold screen support rod; 10—mechanical thermal switch; 11—oxygen-free copper braid; 12—vibration damper; 13—GM refrigerator; 14—evacuation pipeline; 15—evacuation pipeline vibration-reducing bellows; 16—GM refrigerator vibration-reducing bellows; 17—intake heat exchanger; 18—flow resistance; 19—evacuation pipeline transition bellows; 20—distillation chamber; 21—continuous heat exchanger; 22—step heat exchanger; 23—mixing chamber. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0026] like Figure 1-2 As shown: a cryogenic system based on a GM refrigerator to achieve ultra-low vibration below 2K, the cryogenic system comprises a target vibration reduction cold screen 7 and a secondary cold screen 6, a primary cold screen 5 and a vacuum chamber 4 which are sequentially sleeved on the outside of the target vibration reduction cold screen 7 and the four are coaxially arranged, the target vibration reduction cold screen 7 is independently fixed to the target vibration reduction cold screen independent bracket 2 through the target vibration reduction cold screen support rod 9, the vacuum chamber 4 is independently suspended on the vacuum chamber independent bracket 3 arranged in the inner cavity formed by the target vibration reduction cold screen independent bracket 2, and the target vibration reduction cold screen independent bracket 2 and the vacuum chamber independent bracket 3 are both fixedly arranged on a vibration-free ground 1 and there is no direct contact between the two, and the target vibration reduction cold screen support rod 9 is connected to the vacuum chamber 4 by the target vibration reduction cold screen vibration reduction bellows 8; the secondary cold screen 6 is fixed on the coaxial primary cold screen 5 through an independent support rod, and the primary cold screen 5 is fixed on the upper cover of the coaxial vacuum chamber 4 through an independent support rod, and the connection between the support rod and the target vibration reduction cold screen support rod 9 and the secondary cold screen 6 and the primary cold screen 5 is softly connected by oxygen-free copper braid 11 as a low-temperature cold sink; the GM refrigerator 13 is connected to the vacuum chamber 4 through the GM refrigerator vibration reduction bellows 16. The target vibration reduction cold screen support rod 9 is made of thin-walled stainless steel pipe or G10 rod.

[0027] In order to further improve the vibration reduction effect of the overall system, a vibration damper 12 is provided on the target vibration reduction cold screen independent bracket 2, and a suspension member for suspending the target vibration reduction cold screen 7 is provided on the vibration damper 12; and a fine-tuning mechanism capable of adjusting the position of the target vibration reduction cold screen 7 is provided on the suspension member to ensure the concentricity of the target vibration reduction cold screen 7 with the secondary cold screen 6 and the primary cold screen 5. A vibration damper 12 is provided on the vacuum chamber independent bracket 3, and the upper cover of the vacuum chamber 4 is pressed on the vibration damper 12, so that the vacuum chamber 4 is independently suspended on the vacuum chamber independent bracket 3.

[0028] In order to solve the problem of rapid cooling of the entire system, a disconnectable mechanical thermal switch 10 is provided between the target vibration reduction cold screen 7 and the secondary cold screen 6. The mechanical thermal switch 10 is closed during the initial cooling process, and is disconnected when the temperature drops to about 10K, to ensure that the secondary cold screen 6 is completely disconnected from the part below the target vibration reduction cold screen 7 after the mechanical thermal switch 10 is disconnected. At this time, the part of the target vibration reduction cold screen 7 is in an independent state again. Therefore, when the system is running below 2K, the vibration of the part below the target vibration reduction cold screen 7 can be effectively controlled.

[0029] For the internal supporting shock-absorbing structure part, the first-level cold head and the second-level cold head of the GM refrigerator 13 respectively use oxygen-free copper braids 11 as low-temperature sinks to softly connect the first-level cold screen 5 and the second-level cold screen 6; the connection between the first-level cold screen 5 and the second-level cold screen 6 and the evacuation pipeline 14 respectively uses oxygen-free copper braids 11 as low-temperature sinks for soft connection; the evacuation pipeline 14 is transitionally connected to the vacuum chamber 4 through the evacuation pipeline vibration-damping bellows 15; and the evacuation pipeline 14 is connected to the distillation chamber 20 through the evacuation pipeline transition bellows 19; the first-level cold head and the second-level cold head of the GM refrigerator 13 respectively use oxygen-free copper braids 11 as low-temperature sinks to softly connect the intake heat exchanger 17; the flow resistance 18, the distillation chamber 20, the target vibration-damping cold screen 7, the continuous heat exchanger 21, the step heat exchanger 22 and the mixing chamber 23 are packaged together as an accessory and independently fixed to the target vibration-damping cold screen independent bracket 2 through the target vibration-damping cold screen support rod 9.

[0030] The cryogenic system provided by the present invention is further described below in conjunction with the accompanying drawings.

[0031] Take the dilution refrigerator as an example. Figure 1As shown, the target vibration reduction cold shield independent support 2 and the vacuum chamber independent support 3, which are constructed of aluminum profiles and equipped with vibration absorbers 12, are respectively placed on the vibration-free ground 1 to ensure that there is no direct contact between the target vibration reduction cold shield independent support 2 and the vacuum chamber independent support 3. The vacuum chamber 4 is independently suspended on the vacuum chamber independent support 3 equipped with the vibration absorber 12, the primary cold shield 5 is coaxially fixed to the upper cover of the vacuum chamber 4 through a support rod with small heat leakage, and the secondary cold shield 6 is coaxially fixed to the primary cold shield 5 through a support rod with small heat leakage. The target vibration reduction cold shield 7 is independently fixed to the target vibration reduction cold shield independent support 2 equipped with the vibration absorber 12 through the target vibration reduction cold shield support rod 9. In order to ensure the concentricity of the target vibration reduction cold shield 7 with the secondary cold shield 6 and the primary cold shield 5, a fine-tuning structure is provided on the target vibration reduction cold shield independent support 2. The target vibration reduction cold screen support rod 9 is connected to the vacuum chamber 4 by the target vibration reduction cold screen vibration reduction bellows 8. The bellows can be a soft welded bellows. Since the welded bellows is soft and flexible, it can effectively isolate the transmission of vibration between the vacuum chamber 4 and the target vibration reduction cold screen 7. In order to reduce the heat leakage of the support rod and the target vibration reduction cold screen support rod 9, low-temperature cold sinks are required at each level of cold screens, and all low-temperature cold sinks are softly connected with oxygen-free copper braids 11.

[0032] like Figure 2 The internal supporting shock-absorbing structure of the cryogenic system based on the GM refrigerator to achieve ultra-low vibration below 2K is shown. In order to reduce the vibration of the whole system, the GM refrigerator 13 is softly connected with the GM refrigerator vibration-damping bellows 16, and the GM refrigerator 13 can be independently supported, thereby reducing the impact of the GM refrigerator 13 on the vacuum chamber 4. The primary cold screen 5 is connected to the primary cold head of the GM refrigerator 13 through the oxygen-free copper braid 11, and the secondary cold screen 6 is also connected to the secondary cold head of the GM refrigerator 13 through the oxygen-free copper braid 11. The oxygen-free copper braid 11 can reduce the vibration transmission of the GM refrigerator 13 to the cold screens at each level while ensuring good heat conduction. The evacuation pipeline 14 is connected to the upper flange of the vacuum chamber 4 through the evacuation pipeline vibration reduction bellows 15 to prevent the vibration of the vacuum pump from being transmitted to the inside of the vacuum chamber 4 through the evacuation pipeline 14; the evacuation pipeline 14 is softly connected at the first-level cold screen 5 and the second-level cold screen 6 using oxygen-free copper braids 11, and the evacuation pipeline 14 is transitionally connected to the distillation chamber 20 through the evacuation pipeline transition bellows 19, which reduces the installation stress and the impact on the distillation chamber 20. The intake heat exchanger 17 is also softly connected to the GM refrigerator 13 and the cold screens at each level. The flow resistance 18, the distillation chamber 20, the target vibration reduction cold screen 7, the continuous heat exchanger 20, the step heat exchanger 21 and the mixing chamber 22 can be packaged together as an integral accessory, so that the lower part of the target vibration reduction cold screen 7 can be independently suspended on the target vibration reduction cold screen independent bracket 2, effectively reducing the vibration of the lower part of the target vibration reduction cold screen 7.

[0033] It is further emphasized that inside the vacuum chamber 4, all places where heat conduction connection is required are connected by oxygen-free copper braids 11 with good heat conductivity.

[0034] The target vibration reduction cold shield 7 is to achieve a low temperature below 2K mainly in the form of JT throttling refrigeration, He3 refrigerator, dilution refrigerator, etc. The cold source is a GM refrigerator or a pulse tube refrigerator.

[0035] The present invention is described in detail above in conjunction with the accompanying drawings and specific technical solutions. A person skilled in the art can make various changes below 2K according to the above description, such as replacing the part below the target vibration reduction cold shield with a pure He3 refrigerator and a JT throttling system. Therefore, certain details in the specific technical solutions shall not constitute a limitation of the present invention, and the present invention shall be protected by the scope defined by the attached claims.

Claims

1. A cryogenic system based on a GM refrigerator to achieve ultra-low vibration below 2K, characterized by: The cryogenic system comprises a target vibration reduction cold screen (7) and a secondary cold screen (6), a primary cold screen (5) and a vacuum chamber (4) which are sequentially sleeved on the outside of the target vibration reduction cold screen (7), and the four are coaxially arranged. The target vibration reduction cold screen (7) is independently fixed to a target vibration reduction cold screen independent bracket (2) through a target vibration reduction cold screen support rod (9), and the vacuum chamber (4) is independently suspended on a vacuum chamber independent bracket (3) arranged in the inner cavity formed by the target vibration reduction cold screen independent bracket (2), and the target vibration reduction cold screen independent bracket (2) and the vacuum chamber independent bracket (3) are both fixedly arranged. The secondary cold screen (6) is fixed to the coaxially arranged primary cold screen (5) through an independent support rod, and the primary cold screen (5) is fixed to the upper cover of the coaxially arranged vacuum chamber (4) through an independent support rod. The connection between the support rod and the target vibration reduction cold screen support rod (9) and the secondary cold screen (6) and the primary cold screen (5) is made of oxygen-free copper braid (11) as a low-temperature cold sink for soft connection. The GM refrigerator (13) is connected to the vacuum chamber (4) through the GM refrigerator vibration reduction bellows (16).

2. The cryogenic system for achieving ultra-low vibration below 2K based on the GM refrigerator according to claim 1, characterized in that: A vibration damper (12) is provided on the target vibration damping cold screen independent bracket (2), and a suspension member for suspending the target vibration damping cold screen (7) is provided on the vibration damper (12); and a fine adjustment mechanism capable of adjusting the position of the target vibration damping cold screen (7) is provided on the suspension member to ensure the concentricity of the target vibration damping cold screen (7) with the secondary cold screen (6) and the primary cold screen (5).

3. The cryogenic system for achieving ultra-low vibration below 2K based on the GM refrigerator according to claim 1, characterized in that: A vibration damper (12) is provided on the vacuum chamber independent support (3), and the upper cover of the vacuum chamber (4) is pressed on the vibration damper (12), so that the vacuum chamber (4) is independently suspended on the vacuum chamber independent support (3).

4. The cryogenic system for achieving ultra-low vibration below 2K based on a GM refrigerator according to any one of claims 1 to 3, characterized in that: The target vibration reduction cold shield support rod (9) and the vacuum chamber (4) are connected by a target vibration reduction cold shield vibration reduction bellows (8).

5. The cryogenic system for achieving ultra-low vibration below 2K based on the GM refrigerator according to claim 1, characterized in that: The target vibration reduction cold screen support rod (9) is made of a thin-walled stainless steel tube or a G10 rod.

6. The cryogenic system for achieving ultra-low vibration below 2K based on GM refrigerator according to claim 1, characterized in that: A disconnectable mechanical thermal switch (10) is provided between the target vibration reduction cold shield (7) and the secondary cold shield (6).

7. The cryogenic system for achieving ultra-low vibration below 2K based on a GM refrigerator according to claim 1, characterized in that: The first-stage cold head and the second-stage cold head of the GM refrigerator (13) respectively use oxygen-free copper braids (11) as low-temperature cold sinks to softly connect the first-stage cold screen (5) and the second-stage cold screen (6); the connection points of the first-stage cold screen (5) and the second-stage cold screen (6) with the evacuation pipeline (14) respectively use oxygen-free copper braids (11) as low-temperature cold sinks for soft connection.

8. The cryogenic system for achieving ultra-low vibration below 2K based on the GM refrigerator according to claim 7, characterized in that: The evacuation pipeline (14) is transitionally connected to the vacuum chamber (4) via the evacuation pipeline vibration-damping bellows (15); and the evacuation pipeline (14) is connected to the distillation chamber (20) via the evacuation pipeline transition bellows (19).

9. The cryogenic system for achieving ultra-low vibration below 2K based on a GM refrigerator according to claim 1 or 7, characterized in that: The first-stage cold head and the second-stage cold head of the GM refrigerator (13) respectively use oxygen-free copper braids (11) as low-temperature cold sinks to be flexibly connected to the intake heat exchanger (17).

10. The cryogenic system for achieving ultra-low vibration below 2K based on GM refrigerator according to claim 1, characterized in that: The flow resistance (18), the distillation chamber (20), the target vibration reduction cold screen (7), the continuous heat exchanger (21), the step heat exchanger (22) and the mixing chamber (23) are packaged together as an accessory and are independently fixed to the target vibration reduction cold screen independent bracket (2) through the target vibration reduction cold screen support rod (9).

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