Refrigerator-based direct-cooled dry high-pumping speed cryopump for fusion neutral beam

Abstract

The application belongs to the technical field of low-temperature vacuum obtaining and auxiliary system of nuclear fusion device, and relates to a large-pumping-speed low-temperature pump based on a direct-cooling dry type of refrigerator for fusion neutral beam. In the device, a primary cold head mounting plate is located below a vacuum flange and connected with the lower end of a primary cold head; the upper end of a radiation shield is connected with the primary cold head mounting plate; a secondary cold head mounting plate is located below the primary cold head mounting plate and connected with the lower end of a secondary cold head; a low-temperature adsorption array is connected with the secondary cold head mounting plate; the notch of a C-shaped low-temperature plate faces the pumping direction; the adsorption layer is arranged on the C-shaped low-temperature plate in a block array structure, the block array structure comprises a plurality of independent sub-adsorption layers, and a thermal expansion gap is reserved between adjacent sub-adsorption layers; and a composite fiber pull rod is connected between the vacuum flange and a bearing. The application has the advantages of low cost, large adsorption area, large pumping speed, uniform temperature distribution, long service life, low heat leakage and strong engineering adaptability.

Description

Technical Field

[0001] This invention belongs to the technical field of low-temperature vacuum acquisition and auxiliary systems for nuclear fusion devices, and particularly relates to a high-speed, dry-type cryogenic pump based on a refrigerator for fusion neutral beams. Background Technology

[0002] In nuclear fusion experimental devices and future fusion reactors, the neutral beam injection (NBI) heating system is one of the key auxiliary heating methods for increasing plasma temperature. The NBI system provides a large amount of energy to the plasma by accelerating hydrogen or deuterium atoms to tens to hundreds of keV (kiloelectron volts) before injecting them into the plasma. The neutralization unit requires a continuous supply of a large amount of hydrogen gas (operating at approximately 10 kV) during operation. - If the pressure (on the order of 2 Pa) is not released in time, it will cause pressure imbalance in the entire vacuum system. At the same time, a high vacuum needs to be maintained in the downstream region of the neutralization unit to prevent reionization of the neutral beam. Therefore, the NBI system must be equipped with a high-speed cryogenic pump to maintain the required vacuum environment.

[0003] Cryogenic pumps utilize low-temperature surfaces (approximately 15K and below) to condense or adsorb gas molecules, offering advantages such as high pumping speed per unit area and the ability to achieve a clean vacuum. They are an irreplaceable pumping device in NBI systems. With the increasing scale of nuclear fusion devices and the rise in NBI power, the required pumping capacity of a single NBI cryogenic pump has reached the order of 1000 m³ / s.

[0004] However, existing high-speed cryogenic pumps mainly employ the following two technical approaches, both of which have significant shortcomings.

[0005] One type is the liquid helium-cooled condenser pump.

[0006] The liquid helium cooling condenser pump uses liquid helium as a coolant. The liquid helium flows through pipes inside the cooling panel, cooling the panel to approximately 4.2K (down to 3.7K after depressurization), causing hydrogen molecules to condense on the metal panel surface. The system typically includes a helium liquefaction unit, a gas-liquid separator, a liquid nitrogen precooling system, and transmission pipelines.

[0007] However, liquid helium-cooled condenser pumps have the following drawbacks: First, the system is complex and expensive. Liquid helium cooling condensation pumps require large-scale helium refrigeration equipment and liquid nitrogen supply systems, resulting in high equipment investment and operating costs. Traditional large-scale liquid helium cooling condensation pumps use liquid helium as a coolant, achieving a cryogenic temperature of approximately 4.2K (which can be further reduced to 3.7K) through the flow of liquid helium within the cooling panel. Liquid helium cooling condensation pumps require auxiliary equipment such as large-scale helium liquefaction systems, liquid helium transmission pipelines, liquid nitrogen precooling systems, and gas-liquid separators, making the system complex and costly.

[0008] Secondly, liquid helium systems are subject to high-pressure gas safety regulations, requiring regular safety inspections and complex operation and maintenance. Because liquid helium cooling systems are classified as special equipment related to high-pressure gases, they require regular safety monitoring, resulting in a significant workload for operation and maintenance.

[0009] Third, the pumping speed varies significantly with the operating pressure, and the pumping performance is unstable within the wide pressure range of the NBI (Non-Biologically Injectable) pump. The pumping speed of the condensate pump is strongly dependent on the saturated vapor pressure of the gas being pumped, and is significantly higher than that of the gas being pumped. - ¹Pa to 10 - Within the operating pressure range of ³Pa, the hydrogen pumping speed may vary by nearly three times, making it difficult to maintain stable pumping performance over a wide pressure range.

[0010] Fourth, the cooling panel has a liquid helium pipe structure, and the panel temperature is affected by the flow distribution of liquid helium, posing a risk of uneven temperature. Existing large-scale cold adsorption pumps have long heat conduction paths and poor temperature uniformity in their cold plates, resulting in rapid degradation of pumping performance during continuous high-load operation.

[0011] Another type is the GM-type adsorption cryogenic pump used in semiconductor production lines.

[0012] The commercial GM-type adsorption cryogenic pump for semiconductor production lines is a standardized dry closed-loop cryogenic equipment. It is equipped with a two-stage GM refrigerator. The first stage cold head independently cools the 80K radiation shield, and the second stage cold head cools the adsorption plate with a whole piece of activated carbon attached. It is used for the adsorption and removal of trace amounts of water vapor and hydrogen in small vacuum chambers of semiconductors. It does not require a liquid nitrogen / liquid helium supporting system. The single pump hydrogen pumping speed is 10~80m³ / s, which is suitable for batch and intermittent production.

[0013] Currently, wafer etching and thin film deposition production lines use two-stage GM closed-loop cryogenic pumps in large quantities. These pumps rely on a first-stage cold head to self-cool an 80K radiation screen and a second-stage cold head to cool the screen to 10-15K, combined with a whole activated carbon adsorption plate. The entire process does not require cryogenic liquids such as liquid nitrogen or liquid helium, making it a mature dry vacuum system. However, this type of product is designed for small-cavity, intermittent, low-hydrogen-load semiconductor processes. Directly scaling it up for use in fusion NBI devices would expose inherent structural defects.

[0014] However, commercially available GM-type adsorption cryogenic pumps in semiconductor production lines have the following drawbacks: First, the adaptability of the cooling structure is poor. The single-end cooling layout of the cold plate has high axial thermal resistance, resulting in significant temperature rise at the end face under high hydrogen load and rapid decay of adsorption capacity. The standard model uses a single-end top cold head connected to the cold plate, and the axial temperature difference of the semiconductor short cold plate (short cold plate refers to the height or axial direction) can be controlled within 1K. However, if the scale is increased to meter-long adsorption panels for NBI, the heat transfer path from the cold head to the bottom of the plate is too long. Under steady-state hydrogen extraction conditions, the temperature difference between the top and bottom can reach 4~4.5K, the lower adsorption temperature exceeds the standard, the hydrogen adsorption capacity drops significantly, and the continuous stable operation time is limited.

[0015] Secondly, the adsorption layer lacks resistance to thermal fatigue. The integral plate-type activated carbon adhesive structure has poor resistance to thermal cycling stress and is prone to peeling under high-frequency regeneration conditions, resulting in insufficient long-term pumping stability. Existing activated carbon adsorption layers are integrally coated or bonded structures, which are prone to cracking and detachment under repeated thermal cycling, affecting long-term reliability. Commercial models use integral plate-bonded activated carbon technology, which has low frequency of semiconductor thermal cycling and small deformation amplitude; fusion NBI requires periodic heating and regeneration, and the thermal expansion coefficients of the metal substrate, adhesive layer, and activated carbon are mismatched. After long-term cycling, the adsorption layer is prone to cracking and localized detachment, resulting in a continuous reduction in the effective adsorption area.

[0016] Third, there is a lack of specific optimization for low-temperature heat leakage supports. The existing cryogenic pump support structure suffers from significant heat leakage, resulting in substantial heat loss from the chiller due to heat conduction, limiting achievable pumping speeds and continuous operating times. The mechanical supports lack specific design for low-temperature heat leakage, leading to severe solid-state heat loss from room temperature to the cryogenic region, resulting in significant chiller energy loss. Semiconductor equipment is designed for miniaturization and lightweighting; the cold shield and cold plate supports only meet basic mechanical strength requirements, resulting in significant solid-state heat conduction and leakage. A large amount of chiller energy is ineffectively consumed at the room temperature end, making it unable to withstand the high, continuous hydrogen heat load of NBI (Non-Biological Injection).

[0017] Fourth, the pumping speed and flow channels are not optimized for fusion: Within the limited installation space of an NBI device, a high pumping speed of hundreds to thousands of m³ / s needs to be achieved with a compact structure. The monolithic, fixed structure cannot be disassembled or expanded, making it difficult to adapt to the customized pumping speed requirements of different-scale fusion NBI devices. Cooling configurations and airflow channels are calibrated for small cavities with low gas loads; when scaled up to meter-level large adsorption surfaces, temperature differences become uncontrollable, making it impossible to achieve hydrogen pumping speeds of thousands of cubic meters per second for fusion. Commercial pumps have a rated hydrogen pumping speed of only 10~80 m³ / s per unit, and the inlet baffles and airflow channels are designed for trace amounts of process gas, making it difficult to meet the high hydrogen pumping requirements of hundreds to 1000 m³ / s for NBI.

[0018] Fifth, the modularity of the entire unit is low. Commercial pumps have a fixed, integrated structure, making it impossible to flexibly add or remove adsorption units according to different power NBI devices, resulting in poor engineering adaptability.

[0019] In summary, as magnetic confinement fusion devices iterate towards long pulse and steady-state operation, the NBI neutral beam system places stringent demands on cryogenic pumps, such as continuous high-load hydrogen pumping, uniform plate temperature, low maintenance, and compact high pumping speed. However, existing liquid helium condensation pumps and liquid nitrogen precooling cold adsorption pumps rely on cryogenic liquid supply, resulting in complex systems, high costs, and poor safety. Summary of the Invention This invention aims to at least partially solve one of the technical problems in related technologies. Therefore, one objective of this invention is to provide a cryogenic pump for fusion neutral beams based on a direct-cooling dry-type pump with high pumping speed, characterized by low cost, large adsorption surface, high pumping speed, uniform temperature distribution, long service life, low heat leakage, and strong engineering adaptability.

[0020] This invention relates to a fusion neutral beam cryogenic pump based on a direct-cooled dry-type high-speed cryogenic pump, used for installation in an NBI vacuum container, comprising: A vacuum flange, which is sealed and fixed to the NBI vacuum container; The refrigeration unit is a gas refrigeration unit, which has a primary cold head that provides a cooling capacity of 40~80K and a secondary cold head that provides a cooling capacity of 10~15K; the primary cold head and the secondary cold head pass through the vacuum flange from top to bottom; A primary cold head mounting plate, which is located below the vacuum flange and connected to the lower end of the primary cold head; A radiant screen, the upper end of which is connected to the first-stage cold head mounting plate, and the opening of the radiant screen faces the exhaust direction; A secondary cold head mounting plate, which is located below the primary cold head mounting plate and connected to the lower end of the secondary cold head; The low-temperature adsorption array is composed of at least one low-temperature adsorption unit. Each low-temperature adsorption unit is connected to the secondary cold head mounting plate and is arranged in the radiation screen in a one-to-one correspondence. It includes a C-shaped low-temperature plate and an adsorption layer. The notch of the C-shaped low-temperature plate faces the exhaust direction. The adsorption layer is arranged in a block array structure on the inner surface of the C-shaped low-temperature plate or on the inner and outer surfaces of the C-shaped low-temperature plate. The block array structure includes multiple independent sub-adsorption layers, and thermal expansion gaps are reserved between adjacent sub-adsorption layers. The baffle plate is connected between the bottom of the primary cold head mounting plate and the bottom of the radiation screen, and is distributed in the recesses of each of the C-type low temperature plates; A support member is disposed on the bottom lower surface of the radiation screen; Composite fiber tie rods are distributed outside the radiation screen and connected between the vacuum flange and the load-bearing component.

[0021] Compared with existing technologies, the fusion neutral beam cryogenic pump based on direct cooling dry high-speed pumping unit of the present invention has the following advantages: 1. Completely dry operation, no liquid helium or liquid nitrogen required. The radiation screen is directly cooled by a primary cold head, and the cryogenic adsorption array is directly cooled by a secondary cold head. This eliminates the need for liquid helium and liquid nitrogen systems and their corresponding transmission pipelines, simplifying system configuration and enabling a dry, high-speed cryogenic pump. The system has low complexity and low operating and maintenance costs, and high safety.

[0022] II. Segmented Adsorption Array Structure, Resistant to Cracking and Desquamation. The adsorption layer is designed as a segmented array structure, with pre-reserved thermal expansion gaps between each sub-adsorption layer. This effectively absorbs stress caused by temperature cycling, preventing the existing whole adsorption layer from cracking and desquamating. The low-temperature adsorption array has a long service life, maintains a stable adsorption area, and has long-term reliability.

[0023] 3. Large effective adsorption area. The low-temperature adsorption unit increases the effective adsorption area; the low-temperature adsorption unit adopts a C-shaped low-temperature plate, and the adsorption layer is set on the inner surface of the C-shaped low-temperature plate or on the inner and outer surfaces. Under the same exhaust port size, the low-temperature adsorption surface area is significantly increased, the pumping speed per unit volume is high, and a large pumping speed (up to hundreds of m³ / s to 1000 m³ / s) can be achieved in a compact structure.

[0024] IV. Composite Fiber Tie Rod Heat Leakage Support. Using composite fiber tie rods as suspension support elements balances high strength and low thermal conductivity, significantly reducing heat leakage from room temperature to the low-temperature region, alleviating the load on the refrigerator, and improving the temperature uniformity of load-bearing components, radiation shields, and baffles.

[0025] V. Optimization of heat conduction path and improvement of temperature uniformity. Each low-temperature adsorption unit is connected to the secondary cold head mounting plate. This direct connection method shortens the heat transfer distance from the secondary cold head to the farthest end of the adsorption surface of the low-temperature adsorption array (i.e., the heat transfer path is short), resulting in low temperature rise along the path, good temperature uniformity of the low-temperature adsorption unit, strong continuous pumping capability, and stable operation.

[0026] VI. High modularity and engineering adaptability. The fusion neutral beam uses a modular cryogenic adsorption array based on a direct-cooled dry high-pumping-speed cryogenic pump. The number of cryogenic adsorption units can be flexibly combined according to the pumping speed requirements of the NBI vacuum vessel, which can adapt to fusion devices of different scales and power levels.

[0027] The fusion neutral beam cryogenic pump based on direct cooling dry pumping speed of the refrigerator in this embodiment of the invention is a dry cryogenic pump structure that uses direct cooling by the refrigerator and does not require cryogenic liquid media such as liquid helium or liquid nitrogen. It is suitable for high gas load and high vacuum operation conditions with hydrogen or deuterium as the main gas.

[0028] In some embodiments, the refrigerator may be a GM refrigerator, a pulse tube refrigerator, or a Stirling refrigerator, and the number of refrigerators may be 1 to 10.

[0029] In some embodiments, each of the refrigerators cools one or more of the cryogenic adsorption units.

[0030] In some embodiments, the lower end of the primary cold head and the primary cold head mounting plate, and the lower end of the secondary cold head and the secondary cold head mounting plate are both connected by bolts.

[0031] In some embodiments, the sub-adsorption layer is an activated carbon adsorption layer or a molecular sieve adsorption material layer.

[0032] In some embodiments, the length and width of the sub-adsorption layer are from 10mm×10mm to 50mm×50mm, the thickness of the sub-adsorption layer is 2~5mm, and the thermal expansion gap is 0.5mm~3mm.

[0033] In some embodiments, the sub-adsorption layer is fixed to the C-type low-temperature plate by covering and fixing with a low-temperature resistant adhesive and / or a copper mesh.

[0034] In some embodiments, the cross-sectional shape of the C-type low-temperature plate can be replaced with a combination of U-shaped, V-shaped, corrugated, or flat plate shapes.

[0035] In some embodiments, the secondary cold head mounting plate and the C-type low-temperature plate are connected by bolt pressing, brazing, or soldering.

[0036] In some embodiments, the interface between the secondary cold head mounting plate and the C-type low-temperature plate is coated with thermally conductive silicone grease or indium foil.

[0037] In some embodiments, the surface of the radiating screen is polished or coated with a low emissivity material.

[0038] In some embodiments, the baffle adopts one or a combination of two of the following structures: a louver structure, a honeycomb structure, or a mesh structure.

[0039] In some embodiments, the primary cold head mounting plate, the radiation screen, the secondary cold head mounting plate, and the C-type low-temperature plate are all made of high-conductivity oxygen-free copper.

[0040] In some embodiments, the composite fiber tie rod is made of carbon fiber composite material, glass fiber composite material, aramid fiber composite material, or a multi-segment metal-composite material hybrid tie rod.

[0041] In some embodiments, G10 heat insulation pads are provided between the upper end of the composite fiber tie rod and the vacuum flange, and between the lower end of the composite fiber tie rod and the carrier.

[0042] In some embodiments, temperature sensors and heaters are arranged on the secondary cold head mounting plate, the upper and lower ends of the C-type low-temperature plate, and the radiation screen.

[0043] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0044] Figure 1This is a perspective view of a fusion neutral beam using a cryogenic pump based on a direct-cooled dry-type high-speed pumping unit, according to an embodiment of the present invention. Figure 2 yes Figure 1 Enlarged view of point A in the middle; Figure 3 This is a front view of a fusion neutral beam cryogenic pump based on a direct-cooled dry-type high-speed pumping unit, according to an embodiment of the present invention. Figure 4 yes Figure 3 Cross-sectional view at point BB; Figure 5 yes Figure 4 Enlarged view of point C in the middle; Figure 6 This is a structural diagram of a fusion neutral beam based on a direct-cooled, high-speed, dry cryogenic pump (baffle not shown) according to an embodiment of the present invention. Figure 7 yes Figure 6 Enlarged view of point D in the middle; Figure 8 This is a rear view of a fusion neutral beam cryogenic pump based on a direct-cooled dry-type high-speed pumping unit, according to an embodiment of the present invention. Figure 9 This is a schematic diagram of the C-type low-temperature plate in an embodiment of the present invention; Figure 10 This is a schematic diagram of the structure of the baffle in an embodiment of the present invention.

[0045] Figure Labels Fusion neutral beam based dry high-speed cryogenic pump 1000 with direct cooling from a cryostat; vacuum flange 1; cryostat 2; primary cold head 201; secondary cold head 202; primary cold head mounting plate 3; radiation screen 4; secondary cold head mounting plate 5; cryogenic adsorption array 6; cryogenic adsorption unit 601; C-type cryogenic plate 6011; adsorption layer 6012; sub-adsorption layer 60121; thermal expansion gap 60122; baffle 7; load-bearing component 8; composite fiber tie rod 9; G10 thermal insulation pad 10. Detailed Implementation

[0046] Embodiments of the present invention are described in detail below. Examples of these embodiments are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0047] The following is combined with Figures 1 to 10 The present invention describes a fusion neutral beam using a cryogenic pump 1000 based on a direct-cooling dry-type high-speed cryogenic pump.

[0048] like Figures 1 to 10As shown, the fusion neutral beam of this invention uses a cryogenic pump 1000 based on a direct-cooling dry high-speed cryogenic pump, which is installed in an NBI vacuum container and includes: a vacuum flange 1, a cryogenic pump 2, a primary cold head mounting plate 3, a radiation screen 4, a secondary cold head mounting plate 5, a cryogenic adsorption array 6, a baffle 7, a carrier 8, and a composite fiber tie rod 9.

[0049] Vacuum flange 1 is sealed and fixed to the NBI vacuum container and provides a vacuum sealing interface for the cryogenic pump 1000 based on a direct-cooled dry pumping speed for fusion neutral beam.

[0050] The refrigerator 2 is a gas-fired refrigerator, featuring a primary cold head 201 providing 40-80K cooling capacity and a secondary cold head 202 providing 10-15K cooling capacity; the primary cold head 201 and the secondary cold head 202 pass through the vacuum flange 1 from top to bottom. For example, as... Figure 4 As shown, the cryo-unit 2 is a GM cryo-unit 2. The main body of the cryo-unit 2 is located on the upper side of the vacuum flange 1. The secondary cold head 202 is coaxially arranged with the primary cold head 201 and extends downward from the primary cold head 201. The primary cold head 201 and the secondary cold head 202 pass through the vacuum flange 1 from top to bottom and extend into the NBI vacuum container. The primary cold head 201 and the secondary cold head 202 are located at different temperature levels. The fusion neutral beam uses a cryo-pump 1000 based on a cryo-unit-cooled dry high-speed pumping pump with an electrical interface for transmitting internal monitoring signals such as temperature, pressure, and heating signals to the acquisition system.

[0051] The primary cold head mounting plate 3 is located below the vacuum flange 1 and is connected to the lower end of the primary cold head 201, forming a low thermal resistance connection. The cooling capacity of the primary cold head 201 can be directly transferred to the primary cold head mounting plate 3, resulting in good heat transfer effect.

[0052] The upper end of the radiant screen 4 is connected to the first-stage cold head mounting plate 3, and the opening of the radiant screen 4 faces the exhaust direction. In this way, the first-stage cold head 201 can directly cool the radiant screen 4 through the first-stage cold head mounting plate 3. On the one hand, this eliminates the need for a liquid helium system, a liquid nitrogen system, and corresponding transmission pipelines, significantly reducing system complexity and operation and maintenance costs, and improving safety. On the other hand, it shortens the heat transfer path and improves the temperature uniformity of the radiant screen 4.

[0053] For example, refer to Figures 1 to 3 Each radiation screen 4 includes a base plate, a left side plate, a right side plate, and a rear side plate. The upper edges of the left side plate, the right side plate, and the rear side plate are welded to the lower surface of the primary cold head mounting plate 3. An opening facing the extraction direction is formed between the front edges of the left and right side plates. There are multiple radiation screens 4, arranged side-by-side in the left-right direction. The number of radiation screens 4 can be selected according to actual needs. Radiation screens 4, low-temperature adsorption arrays 6, and baffles 7 are configured in a one-to-one correspondence.

[0054] The primary cold head mounting plate 3 is used to support and cool the radiation screen 4, which can shield the radiant heat from the NBI vacuum container and precool the gas entering the fusion neutral beam using a cryogenic pump 1000 based on a direct-cooling dry pump.

[0055] like Figure 4 and Figure 5 As shown, the secondary cold head mounting plate 5 is located below the primary cold head mounting plate 3 and is connected to the lower end of the secondary cold head 202, forming a low thermal resistance connection. The cooling capacity of the secondary cold head 202 can be directly transferred to the secondary cold head mounting plate 5, resulting in good heat transfer. The low-temperature adsorption array 6 is set inside the radiation screen 4 and consists of at least one low-temperature adsorption unit 601. Each low-temperature adsorption unit 601 is connected to the secondary cold head mounting plate 5 and includes a C-shaped low-temperature plate 6011 and an adsorption layer 6012. The notch of the C-shaped low-temperature plate 6011 faces the exhaust direction. The adsorption layer 6012 is arranged in a block array structure on the inner surface of the C-shaped low-temperature plate 6011 or on both the inner and outer surfaces of the C-shaped low-temperature plate 6011. The block array structure includes multiple independent sub-adsorption layers 60121, with thermal expansion gaps 60122 reserved between adjacent sub-adsorption layers 60121.

[0056] In this way, the secondary cold head 202 can directly cool the cryogenic adsorption array 6 through the secondary cold head mounting plate 5. On the one hand, it eliminates the need for liquid helium system, liquid nitrogen system and corresponding transmission pipelines, greatly reducing system complexity and operation and maintenance costs, and improving safety. On the other hand, it shortens the heat transfer path and improves the temperature uniformity and continuous pumping capability of the C-type cryogenic plate 6011.

[0057] The adsorption layer 6012 is disposed on the inner surface of the C-type cryogenic plate 6011, or on both the inner and outer surfaces of the C-type cryogenic plate 6011. This significantly increases the cryogenic adsorption surface area within a limited exhaust port size, improving the pumping speed per unit volume and achieving high pumping speeds (ranging from hundreds of m³ / s to 1000 m³ / s) in a compact structure. The adsorption layer 6012 adopts a segmented array structure, where the thermal expansion gaps 60122 absorb thermal expansion deformation, preventing the sub-adsorption layers 60121 from cracking and falling off, ensuring long-term stable adsorption area and pumping speed. The secondary cold head mounting plate 5 is directly connected to each cryogenic adsorption unit 601, resulting in a short heat transfer path and improving the temperature uniformity of the secondary cold head mounting plate 5 and the continuous pumping capacity of the cryogenic adsorption unit 601.

[0058] refer to Figure 7The number of secondary cold head mounting plates 5 is the same as the number of refrigerators 2. Each secondary cold head mounting plate 5 is connected to a corresponding secondary cold head 202 of a refrigerator 2, and each C-shaped cryogenic plate 6011 is connected to a corresponding secondary cold head mounting plate 5. Specifically, the secondary cold head mounting plate 5 has a base and extensions that extend forward at intervals, such that the front edges of the two extensions and the base form a C-shape consistent with the cross-section of the C-shaped cryogenic plate 6011. The C-shaped cryogenic plate 6011 is located below the secondary cold head mounting plate 5, and the upper end of the C-shaped cryogenic plate 6011 is fitted and welded to the front edges of the two extensions and the base. This facilitates installation and maintenance.

[0059] Of course, there can be only one secondary cold head mounting plate 5, that is, one secondary cold head mounting plate 5 is connected to multiple secondary cold heads 202 of the refrigeration unit 2.

[0060] Of course, the secondary cold head mounting plate 5 can also be connected to the upper back of the C-type low temperature plate 6011.

[0061] Baffle 7 is connected between the bottom of the primary cold head mounting plate 3 and the radiation screen 4, and is distributed in the recesses of each C-type low-temperature plate 6011. It should be noted that baffle 7 extends through the upper end of the C-type low-temperature plate 6011, the secondary cold head mounting plate 5, and the lower end of the C-type low-temperature plate 6011, but does not contact the C-type low-temperature adsorption unit 601 or the secondary cold head mounting plate 5. Baffle 7 is used to block direct radiation and guide gas molecules into the low-temperature adsorption array 6 to reduce the impact on the probability of gas molecule flow. Baffle 7 can also pre-cool the incoming gas. Specifically, the gas enters from the extraction port, flows through baffle 7 in sequence to reach the adsorption layer 6012. The gas is pre-cooled by baffle 7 when flowing through it, which helps to improve the extraction speed.

[0062] The support component 8 is set on the bottom lower surface of the radiation screen 4 to bear the overall weight of the fusion neutral beam based on the direct-cooling dry high-speed cryogenic pump 1000 and the mechanical load during installation.

[0063] Composite fiber tie rods 9 are distributed outside the radiation screen 4 and connect the vacuum flange 1 and the load-bearing component 8. The composite fiber tie rods 9 have high axial strength and low radial thermal conductivity, which can reduce heat leakage through solid conduction and prevent heat exchange between the load-bearing component 8 and the vacuum flange 1. Simultaneously, the composite fiber tie rods 9 provide mechanical suspension support.

[0064] Compared with existing technologies, the fusion neutral beam cryogenic pump 1000 based on a direct-cooled dry-type high-speed cryogenic pump of the present invention has the following advantages: 1. Completely dry operation, no liquid helium or liquid nitrogen required. The radiation screen 4 is directly cooled by the first-stage cold head 201 and the cryogenic adsorption array 6 is directly cooled by the second-stage cold head 202, eliminating the need for liquid helium system, liquid nitrogen system and corresponding transmission pipelines, simplifying system configuration, realizing a dry high-speed cryogenic pump, with low system complexity and operation and maintenance costs, and high safety.

[0065] II. Segmented Adsorption Array Structure, Resistant to Cracking and Desquamation. The adsorption layer 6012 is designed as a segmented array structure, with thermal expansion gaps 60122 reserved between each sub-adsorption layer 60121. This effectively absorbs the stress caused by temperature cycling, avoiding the cracking and desquamation of the existing whole adsorption layer 6012. The low-temperature adsorption array 6 has a long service life and maintains a stable adsorption area, ensuring long-term reliability.

[0066] Third, large effective adsorption area. The low-temperature adsorption unit 601 increases the effective adsorption area; the low-temperature adsorption unit 601 adopts a C-shaped low-temperature plate 6011, and the adsorption layer 6012 is set on the inner surface of the C-shaped low-temperature plate 6011 or on the inner and outer surfaces. Under the same exhaust port size, the low-temperature adsorption surface area is significantly increased, the pumping speed per unit volume is high, and a large pumping speed (up to hundreds of m³ / s to 1000 m³ / s) can be achieved in a compact structure.

[0067] IV. Composite Fiber Tie Rod 9 for Heat Leakage Support. The composite fiber tie rod 9 is used as a suspension support element, which takes into account both high strength and low thermal conductivity, significantly reducing the heat leakage from room temperature to the low temperature region, reducing the load on the refrigerator 2, and improving the temperature uniformity of the load-bearing component 8, radiation screen 4, and baffle 7.

[0068] V. Optimization of heat conduction path and improvement of temperature uniformity. Each low-temperature adsorption unit 601 is connected to the secondary cold head mounting plate 5. This direct connection method shortens the heat transfer distance (i.e., the heat transfer path) from the secondary cold head 202 to the farthest end of the adsorption surface of the low-temperature adsorption array 6, resulting in a low temperature rise along the path, good temperature uniformity of the low-temperature adsorption unit 601, strong continuous air extraction capability, and stable operation.

[0069] VI. Modular design and strong engineering adaptability. The fusion neutral beam uses a modular cryogenic adsorption array 6 based on a direct-cooled dry high-speed cryogenic pump 1000. The number of cryogenic adsorption units 601 can be flexibly combined according to the pumping speed requirements of the NBI vacuum container, which can adapt to fusion devices of different scales and power levels.

[0070] The fusion neutral beam-based dry high-speed cryogenic pump 1000 with direct cooling by a refrigerator 2 in this embodiment of the invention is a dry cryogenic pump structure that uses a refrigerator 2 for direct cooling and does not require cryogenic liquid media such as liquid helium or liquid nitrogen. It is suitable for high gas load and high vacuum operation conditions with hydrogen or deuterium as the main gas.

[0071] In some embodiments, the chiller 2 may be a GM chiller 2, a pulse tube chiller 2, or a Stirling chiller 2. The GM chiller 2, pulse tube chiller 2, or Stirling chiller 2 are all gas chillers 2, enabling completely dry operation and reducing maintenance costs. The number of chillers 2 can be 1 to 10, and can be flexibly configured according to pumping speed requirements to meet ultra-high pumping speed requirements at the thousand cubic meters per second level.

[0072] In some embodiments, each refrigerator 2 cools one or more low-temperature adsorption units 601, which can be flexibly configured as needed.

[0073] In some embodiments, the lower end of the primary cold head 201 and the primary cold head mounting plate 3, and the lower end of the secondary cold head 202 and the secondary cold head mounting plate 5 are both bolted together. On the one hand, this shortens the heat transfer path, reduces thermal resistance, and allows the primary cold head 201 to directly transfer cooling energy to the primary cold head mounting plate 3, and the secondary cold head 202 to directly transfer cooling energy to the secondary cold head mounting plate 5, resulting in good heat transfer performance. On the other hand, bolted connections facilitate assembly and subsequent maintenance and disassembly.

[0074] In some embodiments, the sub-adsorption layer 60121 is an activated carbon adsorption layer 6012 or a molecular sieve adsorption material layer. The activated carbon adsorption layer 6012 or the molecular sieve adsorption material layer has a high adsorption capacity, which can meet the requirements of high pumping speed.

[0075] In some embodiments, the length and width of the sub-adsorption layer 60121 are from 10mm×10mm to 50mm×50mm, the thickness of the sub-adsorption layer 60121 is 2~5mm, and the thermal expansion gap 60122 is 0.5mm~3mm. This size range ensures sufficient adsorption area and adsorption depth, while the thermal expansion gap 60122 effectively prevents the adsorption layer 6012 from cracking or peeling off as a whole.

[0076] In some embodiments, the sub-adsorption layer 60121 is fixed to the C-type low-temperature plate 6011 by covering and fixing it with a low-temperature resistant adhesive and / or a copper mesh. The method of fixing with the low-temperature resistant adhesive and / or the copper mesh ensures that the sub-adsorption layer 60121 is reliably fixed and not easily detached. Furthermore, the copper mesh does not affect the gas entry into the sub-adsorption layer 60121, and the material of the copper mesh is the same as that of the C-type low-temperature plate 6011, resulting in substantially the same thermal expansion and contraction.

[0077] In some embodiments, the cross-sectional shape of the C-type low-temperature plate 6011 can be replaced with a combination of U-shaped, V-shaped, corrugated, or flat plate shapes to adapt to different spatial layouts and airflow organization requirements.

[0078] In some embodiments, the secondary cold head mounting plate 5 and the C-type low temperature plate 6011 are connected by bolt pressing, brazing or soldering, resulting in lower contact thermal resistance and a shorter heat transfer path.

[0079] In some embodiments, the connection interface between the secondary cold head mounting plate 5 and the C-type low-temperature plate 6011 is coated with thermally conductive silicone grease or indium foil, resulting in lower contact thermal resistance and reliable connection.

[0080] In some embodiments, polishing or attaching a low-emissivity material to the surface of the radiation screen 4 can reduce the surface emissivity of the radiation screen 4.

[0081] In some embodiments, the baffle 7 adopts one or a combination of two of the following structures: louver structure, honeycomb structure, or mesh structure. The baffle 7 is used to block direct radiation and guide gas molecules into the low-temperature adsorption array 6 to reduce the impact on the probability of gas molecule flow. The baffle 7 can also pre-cool the incoming gas. Specifically, the gas enters from the exhaust port and flows through the baffle 7 to the adsorption layer 6012. When the gas flows through the baffle 7, it is pre-cooled by the baffle 7, which helps to improve the extraction speed.

[0082] In some embodiments, the primary cold head mounting plate 3, the radiation screen 4, the secondary cold head mounting plate 5, and the C-type low-temperature plate 6011 are all made of high-conductivity oxygen-free copper. High-conductivity oxygen-free copper has good thermal conductivity, ensuring the overall temperature uniformity of the adsorption array 6.

[0083] In some embodiments, the composite fiber tie rod 9 is made of carbon fiber composite material, glass fiber composite material, aramid fiber composite material, or multi-segment metal-composite material hybrid tie rod. These materials not only bear the weight of the cold mass at low temperatures, but also reduce heat leakage through low axial thermal conductivity.

[0084] In some embodiments, a G10 thermal insulation pad 10 is provided between the upper end of the composite fiber tie rod 9 and the vacuum flange 1, and between the lower end of the composite fiber tie rod 9 and the carrier 8. The G10 thermal insulation pad 10 has a lower thermal conductivity, which can reduce solid thermal leakage.

[0085] In some embodiments, temperature sensors (not shown in the figure) and heaters (not shown in the figure) are arranged on the upper and lower ends of the secondary cold head mounting plate 5, the C-type low temperature plate 6011, and the radiation screen 4. The temperature sensors and heaters are used to monitor the temperature and achieve controllable heating during regeneration.

[0086] In some embodiments, the support member 8 is a crossbeam, and there are two crossbeams arranged in parallel. The two ends of each crossbeam are connected to the vacuum flange 1 by composite fiber tie rods 9. The double crossbeam structure is more stable.

[0087] The following are three specific embodiments of the present invention for a cryogenic pump 1000 based on a direct-cooled dry high-speed cryogenic pump for fusion neutral beam: Example 1 like Figure 1As shown, the fusion neutral beam cryogenic pump 1000 based on direct cooling dry high-speed cryogenic pump of the present invention includes a vacuum flange 1, a cryogenic pump 2, a primary cold head mounting plate 3, a secondary cold head mounting plate 5, a radiation screen 4, a cryogenic adsorption array 6, a baffle 7, a carbon fiber tie rod, a load-bearing component 8, a G10 heat insulation pad 10, a load-bearing crossbeam and an electrical interface.

[0088] The refrigeration unit 2 is a two-stage GM refrigeration unit 2; the first-stage cold head 201 has a cooling temperature of approximately 60K and a cooling capacity of approximately 100W; the second-stage cold head 202 has a cooling temperature of 15K and a cooling capacity of approximately 10W~20W; the radiation screen 4 is an 80K radiation screen; the low-temperature adsorption array 6 is a 15K low-temperature adsorption array; the support component 8 is a support beam. In this embodiment, each low-temperature pump is equipped with multiple refrigeration units 2, and each refrigeration unit 2 is responsible for cooling a group of C-shaped low-temperature plates 6011; the adsorption layer 6012 is an activated carbon adsorption layer 6012; the composite fiber tie rod 9 is a carbon fiber tie rod.

[0089] The first-stage cold head mounting plate 3 is a high-conductivity oxygen-free copper plate with a thickness of 10mm~30mm. It is connected to the first-stage cold head 201 of the GM refrigerator 2 by bolts and coated with thermally conductive silicone grease to achieve a low thermal resistance connection. An 80K radiation screen is welded or bolted to the bottom of the first-stage cold head mounting plate 3.

[0090] The 80K radiation screen is made of high-conductivity oxygen-free copper with a thickness of 3mm to 5mm and the surface is polished to reduce emissivity. A baffle 7 is installed inside the 80K radiation screen. The baffle 7 adopts a louver structure with a blade thickness of 0.5mm to 2mm and a blade spacing of 5mm to 20mm, so that the influence on the probability of gas molecule flow is controlled within an acceptable range.

[0091] The secondary cold head mounting plate 5 is a rectangular or fan-shaped high-conductivity oxygen-free copper plate with a thickness of 15mm~40mm. It is pressed together with the secondary cold head 202 of the GM refrigerator 2 through indium foil. The upper ends of multiple C-shaped low-temperature plates 6011 are connected to the lower part of the secondary cold head mounting plate 5 by brazing, so that the cooling capacity of the refrigerator 2 is conducted to the adsorption surface along the shortest path.

[0092] The C-shaped low-temperature plate 6011 is made of high-conductivity oxygen-free copper with a thickness of 2mm~3mm. It has a C-shaped cross-section, a height of about 400mm, a width of about 250mm, and a spacing of about 20mm between adjacent C-shaped low-temperature plates 6011. The inner and outer surfaces of the C-shaped low-temperature plate 6011 are bonded with a segmented activated carbon adsorption layer 6012 by a low-temperature resistant adhesive.

[0093] The segmented activated carbon adsorption layer 6012 consists of an array of activated carbon blocks with a size of approximately 20mm × 20mm × 3mm, with a gap of approximately 1mm between adjacent activated carbon blocks; the activated carbon blocks are fixed to the surface of the C-shaped low-temperature plate 6011 by covering them with epoxy resin-based low-temperature adhesive or copper mesh.

[0094] Carbon fiber tie rods are installed between vacuum flange 1 and primary cold head mounting plate 3 / 80K radiation screen, and between 80K radiation screen and secondary cold head mounting plate 5 / C-type low temperature plate 6011. The diameter of the carbon fiber tie rods is 6mm~16mm, arranged along the axial direction, and the number is determined according to the load calculation. They not only bear the gravity of the low temperature cold mass, but also reduce heat leakage through low axial thermal conductivity.

[0095] G10 heat insulation pads 10 are installed at mechanical contact points where there is a temperature difference, such as between the primary cold head mounting plate 3 and the vacuum flange 1, and between the secondary cold head mounting plate 5 and the primary cold head mounting plate 3, to block solid thermal short circuits.

[0096] The load-bearing crossbeam is located on the lower end face of the radiant screen 4 and is used to support the overall weight of the cryogenic pump during hoisting and transportation.

[0097] The fusion neutral beam of this invention uses a 1000-type dry-type cryogenic pump with direct cooling from a refrigerator, designed to pump at a speed of 500 m³ / s (hydrogen). Under operating temperature, the temperature of the 80K radiation screen is approximately 60K~80K, the upper temperature of the 15K cryogenic adsorption array is approximately 12K~15K, and the lower temperature is approximately 16K~20K. The temperature difference between the upper and lower ends is controlled within approximately 5K, which is significantly better than the existing long cold plate structure that cools from a single point at the top.

[0098] Example 2: This embodiment focuses on the fixing method of the segmented activated carbon adsorption layer 6012. Shallow grooves or a grid-like positioning structure are machined on the surface of the C-shaped low-temperature plate 6011. The shallow grooves are 0.5mm to 1mm deep and are used to accommodate and position the activated carbon blocks. The back of the activated carbon blocks is pre-coated with a low-temperature adhesive, then pressed into the shallow grooves, and finally covered and fixed with a copper mesh. The copper mesh has through holes to ensure that gas molecules can freely reach the surface of the activated carbon.

[0099] This fixing method allows the activated carbon block to expand or contract freely in the in-plane direction during temperature cycling, avoiding excessive tensile stress that could lead to cracking; at the same time, the copper mesh constrains the normal displacement of the activated carbon block, preventing it from falling off during vibration or regeneration.

[0100] Example 3: This invention utilizes a cryogenic dry-type pump 1000 based on a direct-cooling cryogenic unit (DRU) for the fusion neutral beam, illustrating its operation and regeneration process within an NBI vacuum container. The DRU is a GM cryogenic unit (GMC); the radiation screen 4 is an 80K radiation screen; and the cryogenic adsorption array 6 is a 15K cryogenic adsorption array. During normal operation, the GMC cryogenic unit 2 starts, cooling the 80K radiation screen and the 15K cryogenic adsorption array to the target temperature. A large amount of hydrogen gas generated by the neutralization unit is pre-cooled by the baffle 7 and then enters the 15K cryogenic adsorption array, where it is adsorbed by the activated carbon adsorption layer 6012. Temperature sensors monitor the temperature at key locations in real time; if the temperature at any point exceeds a set threshold, an alarm is triggered or the gas load is reduced.

[0101] When the activated carbon adsorption capacity approaches the safety limit or the operating cycle ends, the regeneration procedure is initiated: the GM refrigerator 2 is shut down or its cooling power is reduced, and the 15K cryogenic adsorption array is heated to 50K~100K via a heater for cryogenic regeneration, releasing the adsorbed hydrogen and nitrogen back into the vacuum container, which is then discharged by the auxiliary vacuum pump group; after regeneration, it is recooled and put back into operation. Because the fusion neutral beam in this embodiment of the invention uses a direct-cooled, high-speed dry cryogenic pump 1000 based on a refrigerator, eliminating the need for liquid helium and liquid nitrogen systems, the regeneration and recooling processes only require controlling the power of the refrigerator 2 and the heater, making operation simple.

[0102] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be regarded as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A cryogenic pump for fusion neutral beam based on a direct-cooled dry-type high-speed cryogenic pump, characterized in that, For installation in an NBI vacuum container, including: A vacuum flange, which is sealed and fixed to the NBI vacuum container; The refrigeration unit is a gas refrigeration unit, which has a primary cold head that provides a cooling capacity of 40~80K and a secondary cold head that provides a cooling capacity of 10~15K; the primary cold head and the secondary cold head pass through the vacuum flange from top to bottom; A primary cold head mounting plate, which is located below the vacuum flange and connected to the lower end of the primary cold head; A radiant screen, the upper end of which is connected to the first-stage cold head mounting plate, and the opening of the radiant screen faces the exhaust direction; A secondary cold head mounting plate, which is located below the primary cold head mounting plate and connected to the lower end of the secondary cold head; The low-temperature adsorption array is composed of at least one low-temperature adsorption unit. Each low-temperature adsorption unit is connected to the secondary cold head mounting plate and is arranged in the radiation screen in a one-to-one correspondence. It includes a C-shaped low-temperature plate and an adsorption layer. The notch of the C-shaped low-temperature plate faces the exhaust direction. The adsorption layer is arranged in a block array structure on the inner surface of the C-shaped low-temperature plate or on the inner and outer surfaces of the C-shaped low-temperature plate. The block array structure includes multiple independent sub-adsorption layers, and thermal expansion gaps are reserved between adjacent sub-adsorption layers. The baffle plate is connected between the bottom of the primary cold head mounting plate and the bottom of the radiation screen, and is distributed in the recesses of each of the C-shaped low temperature plates; A support member is disposed on the bottom lower surface of the radiation screen; Composite fiber tie rods are distributed outside the radiation screen and connected between the vacuum flange and the load-bearing component.

2. The cryogenic pump for fusion neutral beam based on direct cooling dry-type high-speed pumping unit according to claim 1, characterized in that, The refrigeration unit can be a GM refrigeration unit, a pulse tube refrigeration unit, or a Stirling refrigeration unit, and the number of the refrigeration units is 1 to 10.

3. The cryogenic pump for fusion neutral beams based on a direct-cooled, high-speed cryogenic pump according to claim 2, characterized in that, Each of the refrigeration units cools one or more of the low-temperature adsorption units.

4. The cryogenic pump for fusion neutral beams based on a direct-cooled dry-type high-speed cryogenic pump according to claim 1, characterized in that, The lower end of the primary cold head and the primary cold head mounting plate, as well as the lower end of the secondary cold head and the secondary cold head mounting plate, are all connected by bolts.

5. The cryogenic pump for fusion neutral beams based on a direct-cooled dry-type high-speed cryogenic pump according to claim 1, characterized in that, The sub-adsorption layer is an activated carbon adsorption layer or a molecular sieve adsorption material layer.

6. The cryogenic pump for fusion neutral beams based on a direct-cooled dry-type high-speed cryogenic pump according to claim 1, characterized in that, The length and width of the sub-adsorption layer are from 10 mm × 10 mm to 50 mm × 50 mm, the thickness of the sub-adsorption layer is 2 to 5 mm, and the thermal expansion gap is 0.5 mm to 3 mm.

7. The cryogenic pump for fusion neutral beam based on direct cooling dry-type high-speed pumping unit according to claim 1, characterized in that, The sub-adsorption layer is fixed to the C-type low-temperature plate by covering and fixing it with a low-temperature resistant adhesive and / or a copper mesh.

8. The cryogenic pump for fusion neutral beam based on direct cooling dry-type high-speed pumping unit according to claim 1, characterized in that, The cross-sectional shape of the C-type low-temperature plate can be replaced with a combination of U-shaped, V-shaped, corrugated, or flat plate.

9. The cryogenic pump for fusion neutral beam based on direct cooling dry-type high-speed pumping unit according to claim 1, characterized in that, The secondary cold head mounting plate and the C-type low temperature plate are connected by bolt pressing, brazing or soldering.

10. The cryogenic pump for fusion neutral beams based on a direct-cooled, high-speed cryogenic pump according to claim 9, characterized in that, The interface between the secondary cold head mounting plate and the C-type low-temperature plate is coated with thermally conductive silicone grease or indium foil.

11. The cryogenic pump for fusion neutral beams based on a direct-cooled, high-speed cryogenic pump according to claim 1, characterized in that, The surface of the radiation screen is polished or coated with a low emissivity material.

12. The cryogenic pump for fusion neutral beams based on a direct-cooled, high-speed cryogenic pump according to claim 1, characterized in that, The baffle adopts one or a combination of two of the following structures: louver structure, honeycomb structure, or grid structure.

13. The cryogenic pump for fusion neutral beams based on a direct-cooled, high-speed cryogenic pump according to claim 1, characterized in that, The primary cold head mounting plate, the radiation screen, the secondary cold head mounting plate, and the C-type low-temperature plate are all made of high-conductivity oxygen-free copper.

14. The cryogenic pump for fusion neutral beams based on a direct-cooled, high-speed cryogenic pump according to claim 1, characterized in that, The composite fiber tie rod is made of carbon fiber composite material, glass fiber composite material, aramid fiber composite material, or multi-segment metal-composite material hybrid tie rod.

15. The cryogenic pump for fusion neutral beams based on a direct-cooled, high-speed cryogenic pump according to claim 1, characterized in that, G10 heat insulation pads are provided between the upper end of the composite fiber tie rod and the vacuum flange, and between the lower end of the composite fiber tie rod and the bearing member.

16. The cryogenic pump for fusion neutral beams based on a direct-cooled, high-speed cryogenic pump according to claim 1, characterized in that, Temperature sensors and heaters are arranged on the secondary cold head mounting plate, the upper and lower ends of the C-type low-temperature plate, and the radiation screen.

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