Cryogenic vacuum pump for a fusion device

Abstract

The application discloses a kind of cryogenic vacuum pumps for fusion device, discard traditional liquid helium, liquid nitrogen refrigeration medium, adopt refrigerator as the refrigeration source of complete machine, save the complex cryogenic medium supply system, compact structure, simplify field operation maintenance, facilitate fusion device complete machine integration, and design low gas resistance intake structure's baffle, improve the gas quantity of unit time into cold screen inside, by setting precooling plate in front of adsorption array, reduce the direct heat shock of gas to adsorption array, ensure that adsorption array maintains ultra-low temperature, realize the large pumping speed of process gas in fusion device, high capacity capture, valve of pump body is all in the form of pneumatic, electronic components are centrally arranged in control box, effectively resist the influence brought by strong magnetic field, irradiation environment and radio frequency field intensity, pump body sealing and bonding are all selected using inorganic material, avoid hydrogen embrittlement, tritium permeation, tritium exchange and the like, prevent tritium gas leakage.

Description

Technical Field

[0001] This invention belongs to the field of vacuum equipment technology and relates to a cryogenic vacuum pump, specifically a cryogenic vacuum pump for fusion devices. Background Technology

[0002] In order to maintain an ultra-high vacuum environment during plasma experiments, fusion devices require dedicated cryogenic vacuum pumps to remove fusion process gases such as deuterium and tritium. Existing fusion devices mostly use liquid helium or liquid nitrogen as the cooling source for their cryogenic vacuum pumps. The entire system requires a large-scale cryogenic medium storage, transportation, and replenishment system, resulting in a complex overall structure, large equipment size, and cumbersome on-site operation and maintenance procedures, thus limiting the overall integration of the fusion device.

[0003] With the development of small-scale GM cryogenic refrigerator technology, cryogenic vacuum pumps using refrigerators as cold sources have been applied. However, when conventional cryogenic vacuum pumps from refrigerators are directly applied to fusion devices, they face multiple stringent constraints, including strong magnetic fields, neutron irradiation, complex radio frequency electromagnetic fields, and tritium corrosion and permeation. First, the strong magnetic field generated during the operation of the fusion device interferes with the normal operation of the refrigerator motor and causes distortion of the pump's temperature measurement signal, affecting the accuracy of temperature measurement and control. Second, the fusion environment is subject to neutron and gamma-ray irradiation, which interferes with the operation of electronic components in the pump. Furthermore, the pump's sealing media and adhesives are prone to irradiation aging and degradation, leading to equipment failure and safety hazards. Third, the complex radio frequency field in fusion conditions makes ordinary controllers and sensors susceptible to radio frequency interference, causing control failure, measurement data drift, and electromagnetic compatibility issues. Finally, tritium in the fusion process gas, as a radioactive hydrogen isotope, possesses hydrogen embrittlement, metal permeation, and isotope exchange properties, making it prone to tritium permeation and leakage risks, posing radioactive safety hazards.

[0004] On the other hand, there are also the requirements for high pumping speed and high capacity adsorption for process gases such as deuterium and tritium: the gas inlet structure of conventional cryogenic vacuum pumps has high gas resistance due to the setting of baffles, resulting in insufficient pumping speed for light gases such as deuterium and tritium; however, if baffles are not set, the adsorption array will lose its heat insulation barrier, causing the activated carbon to operate at a higher temperature and the adsorption capacity to decrease, which cannot meet the needs of large-capacity gas capture for fusion devices.

[0005] In summary, existing cryogenic vacuum pumps cooled by liquid helium / liquid nitrogen are bulky and complex to operate, while cryogenic vacuum pumps cooled by ordinary refrigeration machines cannot simultaneously achieve the comprehensive performance of strong magnetic field resistance, radiation resistance, electromagnetic compatibility, tritium compatibility, high pumping speed, and high adsorption capacity, making it difficult to directly adapt to the actual use requirements of fusion devices. Summary of the Invention

[0006] To address the technical problems existing in the background art, this invention proposes a cryogenic vacuum pump for fusion devices, which uses a small refrigerator as a cooling source and possesses the characteristics of strong magnetic field resistance, radiation resistance, electromagnetic compatibility, tritium compatibility, high pumping speed, and high capacity adsorption capability for use in fusion devices.

[0007] The objective of this invention can be achieved through the following technical solutions: A cryogenic vacuum pump for a fusion device includes: a vacuum housing, a refrigerator, a cold shield, an adsorption array, and a baffle. One end of the vacuum housing has a pump port for sealing and connecting to the fusion device. The refrigerator is sealed and connected to the other end of the vacuum housing. The cold shield is disposed inside the vacuum housing and connected to the first-stage cold head of the refrigerator. The adsorption array is disposed inside the cold shield and connected to the second-stage cold head of the refrigerator, forming a sleeve-like structure with gradually decreasing temperature from the outside to the inside. The baffle is connected to the end of the cold shield near the pump port via a heat-conducting rod to shield the adsorption array from direct thermal radiation from gas molecules outside the cold shield. The baffle adopts a low-resistance inlet structure to increase the molecular weight of gas entering the cold shield per unit time. A pre-cooling plate is disposed at the end of the adsorption array near the baffle. The pre-cooling plate has vent holes. Gas molecules entering the cold shield first pass through the pre-cooling plate and are then condensed and adsorbed by the adsorption array.

[0008] Furthermore, the adsorption array includes: a heat-conducting support and multiple layers of spaced condensing plates. One end of the heat-conducting support is connected to the secondary cold head of the refrigerator, and the other end passes through multiple layers of condensing plates to connect to the pre-cooling plate. Activated carbon is adhered to the surface of the condensing plates.

[0009] Furthermore, an inorganic adhesive is used as a bonding agent between the activated carbon and the condenser plate, and metal powder is added to the adhesive as an auxiliary heat-conducting material.

[0010] Furthermore, the baffle adopts multiple coaxially arranged annular baffles, which are inclined to form a tortuous channel for gas molecules to pass through between any two adjacent annular baffles. One or more heat-conducting rods are provided, which pass radially through the center of the multiple annular baffles to connect and fix the multiple annular baffles to the inner wall of the cold shield.

[0011] Furthermore, the multi-ring annular baffle, precooling plate, and adsorption array are arranged coaxially in sequence with the same radius, and there is an annular unobstructed air intake channel between the multi-ring annular baffle and the inner wall of the cold screen to form a low air resistance air intake structure.

[0012] Furthermore, it also includes: a regeneration pump valve, a regeneration vent valve, and a safety relief valve connected to the end of the vacuum housing away from the pump port, all of which are pneumatic valves.

[0013] Furthermore, a controller is installed at the end of the vacuum housing away from the pump port. The controller includes a control box and a control circuit board, a conductive silicone sheet, and a solenoid valve assembly arranged inside the control box. The conductive silicone sheet is filled between the control circuit board and the inner wall of the control box. The control circuit board is electrically connected to the solenoid valve assembly and is used to control the output of compressed air from the solenoid valve assembly to drive the regeneration suction valve, the regeneration ventilation valve, and the safety pressure relief valve to open or close.

[0014] Furthermore, a temperature sensor and a vacuum gauge are installed at the end of the vacuum housing away from the pump port. Both the temperature sensor and the vacuum gauge are connected to the control circuit board via shielded signal cables that pass through a metal glancing lock arranged on the control box.

[0015] Furthermore, the regeneration extraction valve, regeneration ventilation valve, and safety relief valve are all connected to the vacuum housing via a vacuum connector with a two-stage containment sealing structure.

[0016] Furthermore, the vacuum connector includes: an inner main connecting pipe and an outer enclosing interlayer. The two ends of the main connecting pipe are connected to the vacuum housing and the corresponding valves through sealing joints to form a first-level sealing structure. The enclosing interlayer is closedly set around the main connecting pipe. The sealing joints at both ends of the main connecting pipe are completely wrapped inside the enclosing interlayer to form a second-level sealing structure. The enclosing interlayer is connected to external negative pressure equipment to maintain a negative pressure state.

[0017] The beneficial effects of this invention are as follows: The cryogenic vacuum pump for fusion devices provided by this invention abandons the traditional liquid helium and liquid nitrogen refrigerants, and uses a refrigerator as the overall cooling source. Its first-stage cold head achieves cryogenic cooling of the cold screen, and the second-stage cold head achieves ultra-low temperature cooling of the adsorption array. This eliminates the need for a complex cryogenic medium supply system, resulting in a compact structure, simplified on-site operation and maintenance, and easy integration into the fusion device. Furthermore, the design incorporates a low-resistance inlet baffle to increase the amount of gas entering the cold screen per unit time. By setting a pre-cooling plate at the front end of the adsorption array, the direct thermal shock of the gas to the adsorption array is reduced. To ensure the adsorption array maintains ultra-low temperatures, enabling high-speed and high-capacity capture of process gases within the fusion device, the pump body valves are all pneumatically operated, and electronic components are centrally located within the control box, effectively resisting the effects of strong magnetic fields, irradiation environments, and radio frequency field strength. Inorganic materials are used for pump body sealing and bonding to avoid hydrogen embrittlement, tritium permeation, tritium exchange, and other issues, preventing tritium leakage. It can be used not only in fusion devices but also in other fields requiring resistance to strong magnetic fields, radiation resistance, electromagnetic compatibility, tritium compatibility, high pump speed, and high-capacity adsorption capabilities. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the present invention.

[0019] Figure 2 This is a schematic diagram of the internal structure of the cold screen of the present invention.

[0020] Figure 3 This is a schematic diagram of the adsorption array of the present invention.

[0021] Figure 4 This is a schematic diagram of the installation of the precooling plate of the present invention.

[0022] Figure 5 This is a schematic diagram of the installation of the valve of the present invention.

[0023] Figure 6 This is a schematic diagram of the structure of the vacuum connector of the present invention. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and 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.

[0025] like Figures 1-2 As shown, this invention provides a cryogenic vacuum pump for a fusion device, comprising: a vacuum housing 1, a refrigerator 2, a cold shield 3, an adsorption array 4, and a baffle 5. One end of the vacuum housing 1 is provided with a pump port 6 for sealing and connecting to the fusion device. Deuterium, tritium, and other gas molecules within the fusion device enter the vacuum housing 1 through the pump port 6. To meet the requirements for resistance to strong magnetic fields, radiation, and tritium compatibility during use, the vacuum housing 1 is made of 316L stainless steel, effectively reducing the impact of strong magnetic fields, radiation, and tritium on the metal material during operation. The refrigerator 2 is sealed and connected to the other end of the vacuum housing 1, and the motor portion of the refrigerator 2 is designed with a permalloy metal casing to reduce the impact of strong magnetic fields on the motor during operation. Specifically, the refrigerator 2 uses a two-stage Gifford-McMahon GM refrigerator, with its first-stage cold head providing a low temperature of 30K-90K and its second-stage cold head providing an ultra-low temperature of 4K-20K. By using a small GM refrigerator instead of liquid helium or liquid nitrogen as the cooling source, the pump structure is simplified, the pump size is reduced, and it is easier to use and operate.

[0026] Both the vacuum housing 1 and the cold shield 3 are cylindrical. The cold shield 3 is coaxially arranged inside the vacuum housing 1, and the adsorption array 4 is coaxially arranged inside the cold shield 3. The vacuum housing 1 is in direct contact with the external environment, and its surface temperature is usually maintained at room temperature of 300K. The cold shield 3 is connected to the first-stage cold head of the refrigerator 2 to maintain the surface temperature of the cold shield 3 at a low temperature of 30K-90K. The adsorption array 4 is connected to the second-stage cold head of the refrigerator 2 to maintain the surface temperature of the adsorption array 4 at an ultra-low temperature of 4K-20K. This forms a sleeve-like structure with the temperature gradually decreasing from the outside to the inside, so that the temperature of gas molecules such as deuterium and tritium entering the vacuum housing 1 is gradually cooled to 4K-20K and eventually adsorbed by the adsorption array 4, thereby continuously reducing the gas molecule density in the fusion device and achieving and maintaining a high vacuum or even an ultra-high vacuum.

[0027] The baffle 5 is connected to the end of the cold screen 3 near the pump port 6 via a heat-conducting rod 7. Utilizing the heat conduction of the heat-conducting rod 7, it maintains a low temperature of 30K-90K synchronized with the cold screen 3, thus shielding the adsorption array 4 from direct thermal radiation by external gas molecules. Specifically, the baffle 5 employs multiple coaxially arranged annular baffles, tilted to create a tortuous channel for gas molecules to pass through between any two adjacent annular baffles. This prevents deuterium, tritium, and other gas molecules at 300K room temperature inside the vacuum shell 1 from directly radiating the surface of the adsorption array 4 along a straight path. Instead, they can only enter the cold screen 3 through multiple reflections. With each reflection, the gas molecules transfer some heat to the cold screen 3 and the baffle 5, thus cooling the adsorption array 4 to 30K-90K before contacting it. This ensures the ultra-low temperature operating environment of the adsorption array 4 and significantly reduces the heat load on the refrigerator 2. In this embodiment, three heat-conducting rods 7 are provided, and the intersection angle of any two heat-conducting rods 7 is 60 degrees. They pass through the center of the multi-ring baffle in the radial direction to connect and fix the multi-ring baffle.

[0028] To meet the requirements of high pumping speed and high adsorption capacity during use, the baffle 5 adopts a low-resistance air intake structure to increase the molecular weight of gas entering the interior of the cold screen 3 per unit time. Specifically, the multi-ring annular baffle is coaxially arranged with the same radius as the adsorption array 4, completely blocking the adsorption array 4 only in the axial direction. Between the multi-ring annular baffle and the inner wall of the cold screen 3, there is an annular unobstructed air intake channel. Gas molecules such as deuterium and tritium in the vacuum shell 1 can quickly enter the interior of the cold screen 3 along the inner wall of the cold screen 3 through the annular unobstructed air intake channel, forming a low-resistance air intake structure.

[0029] To further ensure the ultra-low temperature operating environment of the adsorption array 4, a pre-cooling plate 8 is provided at one end of the adsorption array 4 near the baffle 5. The pre-cooling plate 8 has vent holes. Gas molecules entering the cold shield 3 first pass through the pre-cooling plate 8, are cooled again to 4K-20K, and then condensed and adsorbed by the adsorption array 4. Specifically, as... Figures 3-4As shown, the adsorption array 4 includes a heat-conducting support 41 and multiple layers of spaced-apart condensing plates 42. One end of the heat-conducting support 41 is connected to the secondary cold head of the refrigerator 2, and the other end passes through the multiple layers of condensing plates 42 to connect to the pre-cooling plate 8. This utilizes the heat conduction effect of the heat-conducting support 41 to maintain the pre-cooling plate 8 at a low temperature of 4K-20K, synchronized with the adsorption array 4. The surface of the condensing plate 42 is coated with activated carbon with a large specific surface area. At the extremely low temperature of 4K-20K, gas molecules such as deuterium and tritium are firmly bound to the surface of the activated carbon micropores through physical adsorption.

[0030] To meet the requirements for radiation resistance and tritium compatibility during use, all sealing media within the vacuum housing 1 are made of metal sealing materials or inorganic materials such as sintered glass. An inorganic adhesive is used as a binder between the activated carbon and the condenser plate 42 to prevent organic degradation due to radiation, tritium embrittlement, tritium permeation, and tritium exchange. Furthermore, metal powder is added to the inorganic adhesive as an auxiliary heat-conducting material to improve its thermal conductivity, reduce the temperature difference in heat transfer, and consequently lower the temperature of the activated carbon on the surface of the adsorption array 4, thereby increasing the adsorption capacity of the adsorption array 4.

[0031] like Figure 5 As shown, the end of the vacuum housing 1 furthest from the pump port 6 is also connected to a regeneration ventilation valve 9, a regeneration extraction valve 10, and a safety relief valve 11. When the cryogenic vacuum pump is working normally, the pump port 6 of the vacuum housing 1 is connected to the fusion device, and the regeneration ventilation valve 9, regeneration extraction valve 10, and safety relief valve 11 are all closed. The refrigerator 2 continuously provides cooling, and the adsorption array 4 cryogenically captures gas molecules such as deuterium and tritium within the fusion device. When the gas molecules captured by the adsorption array 4 reach saturation, a regeneration process needs to be performed: the pump port 6 is closed, the regeneration ventilation valve 9 and the regeneration extraction valve 10 are opened, and high-purity nitrogen or other dry purging gases are introduced into the vacuum housing 1 through the regeneration ventilation valve 9. Simultaneously, the refrigerator 2 is stopped and heated to desorb the gas molecules adsorbed by the adsorption array 4, restoring its adsorption capacity. During this process, the regeneration extraction valve 10 maintains a negative pressure state, discharging the desorbed mixed gas outwards for processing. After regeneration is complete, close the regeneration vent valve 9 and the regeneration extraction valve 10, open the pump port 6, and the refrigerator 2 restarts refrigeration, returning the cryogenic vacuum pump to its pumping operation. The safety relief valve 11 is mainly used for pressure relief protection when the internal pressure of the vacuum housing 1 exceeds the limit; it is a safety function valve. For example, if the cryogenic vacuum pump experiences an unexpected temperature rise leading to a large amount of gas desorption or desorption during regeneration, the internal pressure of the vacuum housing 1 will rise rapidly. When the pressure reaches the threshold of the safety relief valve 11, it will passively open to release pressure, preventing the cryogenic vacuum pump from exceeding its pressure limit and ensuring the structural safety of the equipment.

[0032] To meet radiation resistance requirements during use, the regeneration ventilation valve 9, regeneration extraction valve 10, and safety relief valve 11 are all pneumatic valves to prevent electronic components from being affected by the radiation environment. A controller 12 is installed at the end of the vacuum housing 1 furthest from the pump port 6. The controller 12 includes a control box and a control circuit board and solenoid valve assembly arranged within the control box. The control circuit board is electrically connected to the solenoid valve assembly and is used to control the output of compressed air from the solenoid valve assembly to drive the regeneration ventilation valve 9, regeneration extraction valve 10, and safety relief valve 11 to open or close. To meet the requirements for resistance to strong magnetic fields, radiation, and electromagnetic compatibility during use, the control box is made of 316L stainless steel, and conductive silicone sheets are filled between the control circuit board and the inner wall of the control box to block the influence of strong magnetic fields, radiation, and radio frequency fields in the working environment on the control circuit board and solenoid valve assembly.

[0033] A temperature sensor 13 and a vacuum gauge tube 14 are installed at the end of the vacuum housing 1 furthest from the pump port 6. The temperature sensor 13 measures the temperature inside the vacuum housing 1, and the vacuum gauge tube 14 measures the vacuum level inside the vacuum housing 1. The temperature sensor is a resistive temperature sensor to reduce the influence of the ambient radio frequency field strength on the measurement accuracy during operation. Both the temperature sensor 13 and the vacuum gauge tube 14 are connected to the control circuit board via shielded signal cables passing through a metal gland lock arranged on the control box, further blocking the influence of the radio frequency field strength on the inside of the controller 12.

[0034] The regeneration vent valve 9, regeneration extraction valve 10, and safety relief valve 11 are all connected to the vacuum housing 1 via a two-stage enclosed sealing vacuum connector 20 to prevent tritium leakage. For example, Figure 6 As shown, the vacuum connector 20 includes an inner main connecting pipe 21 and an outer enclosing interlayer 22. The main connecting pipe 21 allows the flow of gas molecules such as deuterium and tritium. Both ends of the main connecting pipe 21 are connected to the vacuum housing 1 and corresponding valves through sealing joints, forming a first-level sealing structure. The enclosing interlayer 22 is closedly disposed around the main connecting pipe 21. The sealing joints at both ends of the main connecting pipe 21 are completely enclosed within the enclosing interlayer 22. When tritium permeates or leaks slightly at the sealing joints of the inner main connecting pipe 21, the leaked tritium gas will be confined within the outer enclosing interlayer 22, forming a second-level sealing structure to prevent tritium gas from leaking into the external environment. The enclosed interlayer 22 is connected to an external negative pressure device to maintain a negative pressure state. Under negative pressure, the external atmospheric pressure is greater than the internal pressure of the enclosed interlayer 22. Gas can only flow into the enclosed interlayer 22 from the external environment, while the tritium gas that enters the enclosed interlayer 22 cannot escape to the external environment. The leaked tritium gas can be drawn away by the negative pressure and sent to the tritium gas recovery system, thus achieving dual protection against tritium leakage.

[0035] The above description is merely an example and illustration of the structure of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the structure of the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A cryogenic vacuum pump for a fusion device, characterized in that, include: The vacuum shell (1), refrigerator (2), cold shield (3), adsorption array (4), and baffle (5) are arranged in a sleeve structure with a gradually decreasing temperature from the outside to the inside. The vacuum shell (1) has a pump port (6) for sealing and connecting the fusion device at one end. The refrigerator (2) is sealed and connected to the other end of the vacuum shell (1). The cold shield (3) is located inside the vacuum shell (1) and connected to the first-stage cold head of the refrigerator (2). The adsorption array (4) is located inside the cold shield (3) and connected to the second-stage cold head of the refrigerator (2), forming a sleeve structure. The baffle (5) is also included. 5) The heat-conducting rod (7) is connected to the end of the cold screen (3) near the pump port (6) to shield the direct thermal radiation of gas molecules outside the cold screen (3) to the adsorption array (4). The baffle (5) adopts a low gas resistance air intake structure to increase the molecular weight of gas entering the cold screen (3) per unit time. A pre-cooling plate (8) is provided at the end of the adsorption array (4) near the baffle (5). The pre-cooling plate (8) has air vents. The gas molecules entering the cold screen (3) first pass through the pre-cooling plate (8) and are then condensed and adsorbed by the adsorption array (4).

2. The cryogenic vacuum pump according to claim 1, characterized in that, The adsorption array (4) includes a heat-conducting bracket (41) and a multi-layered condensing plate (42). One end of the heat-conducting bracket (41) is connected to the secondary cold head of the refrigerator (2), and the other end passes through the multi-layered condensing plate (42) and is connected to the precooling plate (8). Activated carbon is adhered to the surface of the condensing plate (42).

3. The cryogenic vacuum pump according to claim 2, characterized in that, An inorganic adhesive is used as a binder between activated carbon and condenser plate (42), and metal powder is added to the adhesive as an auxiliary heat-conducting material.

4. The cryogenic vacuum pump according to claim 1, characterized in that, The baffle (5) adopts a multi-ring coaxially arranged annular baffle. The annular baffle is inclined to form a tortuous channel for gas molecules to pass through between any two adjacent annular baffles. One or more heat-conducting rods (7) are provided. The heat-conducting rods (7) pass through the center of the multi-ring annular baffles radially to connect and fix the multi-ring annular baffles to the inner wall of the cold screen (3).

5. The cryogenic vacuum pump according to claim 4, characterized in that, The multi-ring baffle, precooling plate (8), and adsorption array (4) are arranged coaxially and sequentially with the same radius. There is an annular unobstructed air intake channel between the multi-ring baffle and the inner wall of the cold screen (3) to form a low air resistance air intake structure.

6. The cryogenic vacuum pump according to claim 1, characterized in that, Also includes: The regeneration ventilation valve (9), regeneration extraction valve (10) and safety relief valve (11) are connected to the end of the vacuum housing (1) away from the pump port (6). The regeneration ventilation valve (9), regeneration extraction valve (10) and safety relief valve (11) are all pneumatic valves.

7. The cryogenic vacuum pump according to claim 6, characterized in that, A controller (12) is installed at the end of the vacuum housing (1) away from the pump port (6). The controller (12) includes a control box and a control circuit board, a conductive silicone sheet and a solenoid valve group arranged in the control box. The conductive silicone sheet is filled between the control circuit board and the inner wall of the control box. The control circuit board is electrically connected to the solenoid valve group and is used to control the output of compressed air from the solenoid valve group to drive the regeneration ventilation valve (9), the regeneration extraction valve (10) and the safety pressure relief valve (11) to open or close.

8. The cryogenic vacuum pump according to claim 7, characterized in that, A temperature sensor (13) and a vacuum gauge tube (14) are installed at the end of the vacuum housing (1) away from the pump port (6). Both the temperature sensor (13) and the vacuum gauge tube (14) are connected to the control circuit board through shielded signal cables passing through the metal glancing lock arranged on the control box.

9. The cryogenic vacuum pump according to claim 6, characterized in that, The regeneration ventilation valve (9), the regeneration extraction valve (10), and the safety relief valve (11) are all connected to the vacuum housing (1) via a vacuum connector (20) with a two-stage enclosed sealing structure.

10. The cryogenic vacuum pump according to claim 9, characterized in that, The vacuum connector (20) includes an inner main connecting pipe (21) and an outer enclosing interlayer (22). The two ends of the main connecting pipe (21) are connected to the vacuum housing (1) and the corresponding valves through sealing joints to form a first-level sealing structure. The enclosing interlayer (22) is closedly set around the main connecting pipe (21). The sealing joints at both ends of the main connecting pipe (21) are completely wrapped in the enclosing interlayer (22) to form a second-level sealing structure. The enclosing interlayer (22) is connected to an external negative pressure device to maintain a negative pressure state.

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