Vacuum low-temperature platform and method for inflating and freezing target pellets

Abstract

The present application provides a kind of vacuum low temperature platform and frozen target target pellet inflation and freezing method, comprising: vacuum cover, which provides mechanical appearance and physical support;Vacuum pump, for pure environment and vacuum insulation;Cold screen cover, for blocking the room temperature environment outside vacuum pump, provide first-stage temperature control for target pellet gas;Vacuum cover and cold screen cover are provided with detachable flange, air inlet valve, detachable cavity, observation window;Low-temperature copper block, which is located in cold screen cover;Target holder clamp, one end is fixed to the side wall of low-temperature copper block, the other end is used to clamp frozen target holder and conduct the temperature of low-temperature copper block;Connecting hose, which guides input gas from air inlet valve to frozen target holder, and at least one connecting hose passes through low-temperature copper block.The present application provides three-stage temperature control to obtain lower temperature and pure vacuum environment;Isolate the ultra-low temperature of low-temperature copper block, reduce the risk of frostbite of operator, and have temperature control buffer, improve the safety of equipment.

Description

Technical Field

[0001] This invention relates to the field of gas filling and freezing technology for cryogenic targets, specifically, to a vacuum cryogenic platform and a method for gas filling and freezing cryogenic targets. Background Technology

[0002] In an era where energy issues are increasingly becoming a core concern for national security and social stability, controlled thermonuclear fusion has the potential to provide humanity with abundant, economical, and secure energy. Inertial confinement fusion is one promising method for achieving controlled thermonuclear fusion. The basic idea of ​​inertial confinement fusion is to provide energy to the fuel layer of a spherical target pellet, causing it to become plasma and undergo extremely rapid centripetal motion, thus being compressed to nuclear fusion conditions under its own inertial confinement.

[0003] The main target pellet fuel layer materials in this process are deuterium and tritium. Whether powered directly or indirectly by laser drive, ICF relies on a thick-shell, cryogenic deuterium-tritium spherical target pellet with a liquid or solid fuel layer. Currently, the methods for forming such thick-shell, cryogenic deuterium-tritium frozen target pellets are mainly divided into two types: direct freezing deposition using an external cryogenic environment and freezing deposition using an adsorption carrier. The latter method has received widespread attention due to its simple design and good adsorption effect. Several works, including T. Norimatsu et al.'s "Issue in capsule fabrication and injection into a wet-walled IFEreactor," Du Kai et al.'s "Development of Polymer Foam Spherical Shells for Cryogenic Targets," and RLMcCrory et al.'s "Direct-drive inertial confinement fusion research at the Laboratory for Laser Energetics: charting the path to thermonuclear ignition," have all employed foam microspheres to assist in the adsorption formation of the fuel layer.

[0004] Whether through direct freezing deposition or assisted adsorption deposition, the deposition of fuel layers in cryogenic spherical targets requires an external cryogenic environment and a suitable temperature-controlled freezing strategy. In 2020, Zhang Yong et al. from Southwest University of Science and Technology used Solidworks and finite element simulation to explore the temperature control requirements of the cryogenic target on the cryogenic shield system; their findings were published at the 12th National Conference on Nuclear Target Technology. In 2021, Chen Guanhua et al. from Xi'an Jiaotong University conducted a dynamic analysis of temperature disturbance characteristics of the cryogenic target shield based on user-defined functions and a discrete coordinate radiation model. In 2022, Li Cui et al. from Xi'an Jiaotong University established a three-dimensional mathematical model of the discrete coordinate radiation model to explore the influence of residual fuel ice in the micro-inflating tube on the temperature control process of the cryogenic target. The results showed that the maximum temperature difference on the target surface first decreased and then increased with the increase of the fuel ice length in the tube; when the fuel ice length in the tube was 0.09 mm, a better temperature control effect could be achieved.

[0005] However, the above-mentioned work and various domestic and international studies on cryogenic temperature control are mostly based on theoretical models and simulation results. In contrast, the results of cryogenic target work based on experimental verification have significant shortcomings. There is an urgent need for a cryogenic target pellet inflation and freezing device based on a vacuum cryogenic platform. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide a method for gas-filling and freezing frozen targets based on a vacuum cryogenic platform.

[0007] According to a first aspect of the present invention, a vacuum cryogenic platform is provided, comprising:

[0008] A vacuum enclosure, located on the outer layer, provides mechanical shape and physical support for the vacuum cryogenic platform, and its internal space constitutes the vacuum enclosure cavity;

[0009] A vacuum pump, connected to the vacuum shroud, provides a pure environment and vacuum insulation for the vacuum shroud cavity;

[0010] A cold shield is located in the inner layer of the vacuum chamber and is used to block the room temperature environment outside the vacuum pump. Its internal space forms a cold shield cavity to provide primary temperature control for the target gas.

[0011] The vacuum hood and the cold screen hood are equipped with detachable flanges, air inlet valves and detachable cavities, and the detachable cavity is equipped with an observation window for the cryogenic target rack;

[0012] A low-temperature copper block, the low-temperature copper block being located inside the cooling screen;

[0013] A target holder clamp, one end of which is fixed to the side wall of the low-temperature copper block, and the other end is used to clamp the freezing target holder and conduct the temperature of the low-temperature copper block to it, providing primary temperature control;

[0014] A connecting hose is provided, which guides the input gas from the inlet valve to the cryogenic target holder, and at least one connecting hose passes through the cryogenic copper block.

[0015] Preferably, the target holder clamp is made of copper or gold-plated copper, with one end threadedly fastened to the low-temperature copper block and the other end directly clamping and contacting the freezing target holder.

[0016] Preferably, the observation window is located on the right-side detachable cavity, with a window diameter of 1-5 inches, and is located at the top, front, and rear, respectively, for microscope imaging, X-ray phase imaging, and infrared homogenization observation.

[0017] Preferably, the detachable flange includes two types: one is a detachable flange that facilitates the installation of the vacuum shroud and the cooling screen, which is installed on the top or bottom of the vacuum shroud; the other is a detachable flange that facilitates the installation of the detachable cavity, which is installed on the right side of the vacuum shroud.

[0018] The intake valve includes two types: one is a target gas intake valve, which is installed on the top of the vacuum chamber, and if there is a detachable flange on the top, it is installed at the detachable flange on the top; the other is a liquid helium intake valve, which is connected to the existing refrigeration system and installed on the side of the vacuum chamber.

[0019] Preferably, the connecting hose is a polyimide hose, and the number of turns and the winding distance of the low-temperature copper block are adjusted according to the results obtained from the observation window of the freezing process.

[0020] According to a second aspect of the present invention, a method for gas-filling and freezing cryogenic targets based on the above-described vacuum cryogenic platform is provided, comprising:

[0021] Fuel gas is introduced through the intake valve and passed through the cooling shield for primary temperature control;

[0022] The fuel gas undergoes secondary temperature control through the cryogenic copper block, and when it flows to the cryogenic target frame, it is in a liquefied state and wets the double cones inside the cryogenic target.

[0023] Liquid helium gas is introduced through the inlet valve to the cryogenic target frame, increasing the gas pressure inside the cryogenic target while reducing the temperature of the fuel gas, thus achieving three-stage temperature control and solidifying the fuel gas.

[0024] Preferably, the fuel gas flows from the fuel gas tank into the top inlet valve of the cryogenic vacuum platform via a high-precision flow meter and an absolute pressure sensor.

[0025] The top air inlet valve steel pipe passes through the top through hole of the cold shield cavity for primary temperature control of the target gas.

[0026] Subsequently, the target gas path is connected via a polyimide gas path hose, and the target gas path hose is placed close to the low-temperature copper block for secondary temperature control of the target gas. The fuel gas is in a liquefied state to wet the double cone inside the frozen target.

[0027] Liquid helium flows from the liquid helium tank into the inlet valve inside the cryogenic vacuum platform cavity via a high-precision flow meter and a high-precision thin-film gauge. Then, it is connected to a polyimide liquid helium gas hose and introduced into the double cone inside the cryogenic target to cool the liquefied gas, achieving three-stage temperature control.

[0028] Preferably, the fuel gas is deuterium, tritium, hydrogen, or a mixture of gases.

[0029] Preferably, the performance indicators of the high-precision flow meter include: a gas flow control range of 0-5 mL / min and an accuracy of ±1%FS;

[0030] The performance specifications of the absolute pressure sensor include: a measurement range of 0-1.6×10⁻⁶. 5 Pa, with an accuracy of 0.01%FS;

[0031] The performance specifications of the high-precision thin-film gauge include: a measuring range of 10⁻¹×10⁻¹ 5 Pa, with an accuracy of 0.15%FS.

[0032] Preferably, the temperature of the cold shield is 50K, and the temperature of the low-temperature copper block is 5-20K.

[0033] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0034] 1. The vacuum cryogenic platform in this embodiment of the invention can provide three-level temperature control to obtain a lower temperature and a pure vacuum environment; the cold shield isolates the ultra-low temperature of the low-temperature copper block, reduces the risk of frostbite to operators, and improves equipment safety; and the cold shield itself also obtains a buffer temperature, which can be used for temperature control buffering.

[0035] 2. The vacuum cryogenic platform in this embodiment of the invention provides multiple functions, including an observation window that can be used for infrared homogenization observation, X-ray phase imaging and microscopic imaging; the detachable flange on the top of the cryogenic vacuum platform and the detachable flange on the right side cavity ensure the convenience of gas path assembly and disassembly, giving the platform a certain degree of flexibility.

[0036] 3. In the frozen target pellet inflation and freezing method of this embodiment of the invention, the frozen target frame undergoes primary temperature control via a target frame clamp, and the target pellet gas passes through a three-stage temperature control system: a cold shield, a low-temperature copper block, and liquid helium. Furthermore, the temperature control effect of the low-temperature copper block is adjustable based on the winding of the flexible tubing. This multi-stage temperature control strategy ensures the smooth progress of the freezing process.

[0037] 4. The method for filling and freezing frozen target pellets in the embodiments of the present invention is equipped with a gas flow meter and a gas pressure gauge, which together with microscopic imaging constitute a relatively complete control and monitoring mechanism. Attached Figure Description

[0038] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0039] Figure 1a This is a top view of the overall structure of a vacuum cryogenic platform according to an embodiment of the present invention;

[0040] Figure 1b This is a cross-sectional view of the cavity according to an embodiment of the present invention;

[0041] Figure 2 This is a schematic diagram of the overall structure of the vacuum cryogenic platform according to another embodiment of the present invention;

[0042] Figure 3 This is a flowchart of a method for gas filling and freezing of frozen target pellets based on a vacuum cryogenic platform according to an embodiment of the present invention.

[0043] Figure 4 This is a flowchart of a method for filling and freezing frozen target pellets based on a vacuum cryogenic platform, according to another embodiment of the present invention.

[0044] Figure 5a This is a top view of a cryogenic target holder in one embodiment; Figure 5b Its front view.

[0045] In the diagram: 101 is the target holder fixture, 102 is the low-temperature copper block, 103 is the observation window, 104 is the vacuum chamber, 105 is the cold shield, 106 is the KF25 optical flange, 107 is the inlet valve, 108 is the top removable flange, 109 is the right removable flange, and 110 is the polyimide hose; 203 is the observation window, 204 is the vacuum chamber, 206 is the KF25 optical flange, 207 is the inlet valve, 208 is the bottom removable flange, and 211 is the rear cooling system. Detailed Implementation

[0046] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0047] This invention provides an embodiment of a vacuum cryogenic platform, comprising a vacuum shroud 104, a vacuum pump, a cold shield 105, a cryogenic copper block 102, a target holder clamp 101, and a connecting hose 110. The vacuum shroud 104 is located on the outer layer, providing the mechanical shape and physical support for the vacuum cryogenic platform; its internal space constitutes the vacuum shroud cavity. The vacuum pump is connected to the vacuum shroud 104, providing a pure environment and vacuum insulation for the vacuum shroud cavity. The cold shield 105 is located on the inner layer of the vacuum shroud 104, used to block the room temperature environment outside the vacuum pump; its internal space constitutes the cold shield cavity, providing primary temperature control for the target gas. The vacuum shroud 104 and the cold shield 105 are equipped with detachable flanges, each fitted with an inlet valve. One side of the vacuum chamber and the cold screen chamber is a detachable chamber, and an observation window 103 for the cryogenic target frame is provided on the detachable chamber; the low-temperature copper block 102 is located inside the cold screen 105; one end of the target frame clamp 101 is fixed to the side wall of the low-temperature copper block 102, and the other end is used to clamp the cryogenic target frame and conduct the temperature of the low-temperature copper block to it, providing primary temperature control; the connecting hose 110 guides the input gas from the inlet valve to the cryogenic target frame, and at least one connecting hose passes through the low-temperature copper block 102.

[0048] The cryogenic vacuum platform in this embodiment provides three-stage temperature control to achieve a low temperature and a pure vacuum environment. The cold shield isolates the ultra-low temperature of the cryogenic copper block, reducing the risk of frostbite to operators and improving equipment safety. Furthermore, the cold shield itself gains a buffer temperature, which can be used for temperature control. The cryogenic vacuum platform in this embodiment provides multiple functions, including observation windows for infrared homogenization observation, X-ray phase imaging, and microscopic imaging. The detachable flanges on the top and right side of the platform ensure convenient assembly and disassembly of the gas path, giving the platform a degree of flexibility.

[0049] In a preferred embodiment of the invention, the target holder clamp 101 is made of copper or gold-plated copper, with one end threadedly fastened to the low-temperature copper block 102 and the other end directly clamping and contacting the cryogenic target holder. The observation window 103 is located on the right-side detachable cavity, with a diameter of 1-5 inches, and is located at the top, front, and rear, respectively, for microscope imaging, X-ray phase imaging, and infrared homogenization observation. Two types of detachable flanges are included: one is a detachable flange 108 for easy installation of the vacuum hood and cold screen, installed at the top or bottom of the vacuum hood; the other is a detachable flange 109 for easy installation of the detachable cavity, installed on the right side of the vacuum hood. Two types of inlet valves are included: one is a target gas inlet valve 107, installed at the top of the vacuum hood, or at the top detachable flange if one exists; the other is a liquid helium inlet valve, connected to the existing refrigeration system and installed on the side of the vacuum hood 104. The connecting hose is made of polyimide hose 110, and the number of turns and the winding distance of the low-temperature copper block are adjusted according to the results obtained from the observation window of the freezing process.

[0050] For ease of understanding, the present invention provides two preferred embodiments of a complete vacuum cryogenic platform. For the first, please refer to Figure 1. (Refer to...) Figure 1a The vacuum cryogenic platform includes two KF25 flanges 106 distributed in the front and rear chambers for inserting optical fibers, facilitating other optical experiments. A detachable flange 107 is located at the top of the platform, with four inlet valves 108 above it. The main purpose of the detachable flange 107 is to increase the flexibility of the inlet valves 108, facilitating installation and removal. The outermost part of the platform is sealed by a vacuum shroud 104. The right end of the vacuum shroud 104 is connected to the chamber with the observation window 103 via a right-side detachable flange 109, together forming the vacuum shroud chamber structure. The main purpose of the right-side detachable flange 109 is to facilitate the installation of the polyimide tubing 110 and the cryogenic target holder. (Refer to...) Figure 1b The cold shield 105 is located inside the vacuum chamber 104, and its right side is connected to the right cavity by a detachable flange, forming the cold shield cavity structure. The gap between the cold shield 105 and the vacuum chamber 104 is 1 cm. The low-temperature copper block 102 corresponds to the top detachable flange 108, and the right side wall is connected to the target holder clamp 101 by a threaded fastener. The clamp is 7 cm long.

[0051] The second one, please refer to Figure 2 The vacuum cryogenic platform includes the same KF25 flange 206 and observation window 203 as in the previous embodiment. The position of the KF25 flange can be adjusted according to the available space within the cavity and is not specifically required. Four inlet valves 207 are distributed at the top, front, and back, respectively. This dispersed arrangement of inlet valves facilitates thorough winding of the cryogenic copper block; however, the inlet valves 207 are fixedly welded to the vacuum shroud 204. The bottom removable flange provides flexibility for adjusting the vacuum cryogenic platform and any possible gas path adjustments. The vacuum shroud 204 is integrally machined with the right-side cavity, unlike the previous embodiment which used a removable right-side flange 109 for connection. It should be noted that... Figure 2 The internal cold shield of the device is also manufactured using an integrated process. In this embodiment, the integrated cavity provides better sealing performance, but on the other hand, it reduces the operational flexibility of the vacuum cryogenic platform. The back-end refrigeration system 211 provides cooling for the cryogenic copper block. The back-end refrigeration system is relatively mature and is not limited in this embodiment.

[0052] Based on the same inventive concept, the present invention provides a method for gas-filling and freezing frozen target pellets based on the above-mentioned vacuum cryogenic platform, comprising:

[0053] S01, fuel gas is introduced through the intake valve, and it passes through the cooling shield to achieve primary temperature control;

[0054] S02, the fuel gas passes through a low-temperature copper block to achieve secondary temperature control, and then flows to the cryogenic target frame in a liquefied state and wets the foam spherical shell of the double cone inside the cryogenic target;

[0055] S03, liquid helium gas is introduced through the inlet valve to the cryogenic target frame, increasing the gas pressure inside the cryogenic target while further reducing the temperature of the fuel gas, realizing a three-stage temperature control process, and solidifying the fuel gas.

[0056] In a preferred embodiment of the present invention, S01 and S02 are implemented. Specifically, refer to Figure 1. Figure 3 and Figure 4 The deuterium-tritium fuel gas cylinder flows into the top gas valve 107 of the vacuum cryogenic platform via a high-precision flow meter and an absolute pressure sensor. The steel pipe of the top gas valve passes through the top through-hole of the cold shield cavity 105, which has a temperature of around 50K, to complete the first-stage temperature control process of the target gas. It is then connected via a specially made polyimide hose 110, and the polyimide hose is placed close to the cryogenic copper block 102 for the second-stage temperature control of the target gas.

[0057] In a preferred embodiment of the present invention, in step S03, liquid helium gas is introduced to increase the gas pressure inside the cryogenic target while further reducing the temperature of the fuel gas below its freezing point, thereby achieving a three-stage temperature control process and solidifying the fuel gas. On the other hand, in order to maintain a constant gas pressure, the partially vaporized target fuel gas and liquid helium gas are extracted by a vacuum pump.

[0058] In a preferred embodiment, the fuel gas for the target pellet is protium, deuterium, tritium, and hydrogen (i.e., a natural mixture of the aforementioned three gases).

[0059] In a preferred embodiment, the temperature of the low-temperature copper block is 5-10K, while the solidification temperature of the target pellet fuel gas is around 20K. In order to prevent the target pellet gas from solidifying and blocking the gas passage during the secondary temperature control, a barrier such as a foam board can be selectively attached between the copper block and the polyimide hose.

[0060] In a preferred embodiment, the high-precision flow meter used is a fuel flow meter of model "CS200A 5SCCM D23MM485", and the absolute pressure sensor is model "RPS / DPS 811A-TB-A2-CC-H0-RF-3.5BAR-7". Liquid helium flows from a liquid helium tank into the gas valve inside the cryogenic vacuum platform cavity, controlled by the high-precision flow meter and monitored by a high-precision diaphragm gauge. It is then connected via a specially made polyimide hose. In this embodiment, the liquid helium flow meter is model "CS200A10SCCM HE 3MM 485".

[0061] In a preferred embodiment, the target gas path hose and the liquid helium gas path hose are fixed to the corresponding positions on the cryogenic target holder, as shown in the reference. Figure 3 The inflation position of the cryogenic target frame Figure 4This is the inflation position for another cryogenic target rack. This embodiment does not limit the structure of the cryogenic target rack; the gas path arrangement is relatively conventional, and the connection between the inflation gas path and the cryogenic target rack can be adjusted according to the specific structure of the cryogenic target rack. Figure 5a and Figure 5b This is a structural diagram of a cryogenic target frame according to an embodiment of the present invention. The support wall of the target frame is made of silicon material, and the total length of the target frame is 4-7cm.

[0062] The key factors in the freezing process lie first in controlling the flow rate and path length of the fuel gas, ensuring sufficient cooling during primary and secondary temperature control without reaching the solidification temperature. Therefore, the above embodiment offers at least three advantages: 1. The polyimide hose wrapping the cryogenic copper block facilitates control of the gas filling path length; 2. The three-stage gradient temperature control strategy minimizes the dependence of fuel gas liquefaction and solidification on the cryogenic copper block, avoiding the risk of over-freezing while allowing for the addition of foam boards between the cryogenic copper blocks to flexibly adjust the freezing temperature; 3. The detachable flange of the cryogenic platform provides the aforementioned two advantages with the feasibility of flexible equipment operation.

[0063] The second key factor is controlling the flow rate of liquid helium and the pumping rate of the vacuum pump to maintain the pressure and temperature at the freezing point of the fuel gas. The top observation window provided in the above embodiments can be used for real-time microscopic imaging, providing researchers with guidance on adjusting the vacuum pumping rate and the flow rate of fuel gas and liquid helium.

[0064] The above benefits will be demonstrated in more detail below with reference to specific embodiments:

[0065] Example 1:

[0066] Based on the vacuum cryogenic platform shown in Figure 1, this platform has two detachable flanges at the top and right side, with four air inlet valves located on the top detachable flange. A super depth-of-field microscope is fixed to the observation window at the top of the platform for X-ray phase imaging and infrared homogenization observation. The cryogenic target holder adopts the structure shown in Figure 5, with a length of 5 cm. The gold cone air inlet uses... Figure 3 The device shown.

[0067] When installing the cryogenic target frame, remove the top and right-side removable flanges. First, connect the cold shield and vacuum hood to the rear refrigeration system. Then, connect the top inlet valve to the top flange and connect the polyimide hose to the 1 / 8 steel pipe of the inlet valve. Use tape to attach the polyimide hose to the cryogenic copper block and lead it to the observation window, with a 5cm attachment length. Leave a 0.5mm foam board gap between the polyimide hose and the cryogenic copper block. Next, connect the top flange to the vacuum hood. Secure the target frame clamp to the right side wall of the cryogenic copper block and connect the cryogenic target frame to the target frame clamp. Then, connect the right-side vacuum hood cavity and cold shield cavity to the main body via the right-side flange. At this point, the gas path and cryogenic target frame are installed, forming an airtight cavity.

[0068] The protium fuel cylinder is introduced into the top gas valve, controlling the gas flow rate of the flow meter while ensuring the fuel gas pressure remains within a safe range. After the 1 / 8 valve steel pipe passes through the cold shield for primary temperature control, the polyimide hose is connected to the 1 / 8 steel pipe. The polyimide hose is attached to the cryogenic copper block without wrapping it around the copper block, and then the hose is connected to the cryogenic target frame. Protium gas is introduced into the tips of the upper and lower gold cones, with a foam spherical shell placed above the gold cone tips to assist in the adsorption of fuel gas. Liquid helium is introduced into the gold cone tips, and the vacuum pump extracts gas. Specifically, liquid helium is extracted above the foam spherical shell, liquid helium is introduced into the outer ring of the gold cones, and fuel gas is extracted at the center of the double gold cone tips.

[0069] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention. The above preferred features can be used in any combination without conflict.

Claims

1. A method for gassing and freezing of a target pellet based on a vacuum cryogenic platform, characterized in that, Comprising: The fuel gas is introduced from the intake valve, and is subjected to primary temperature control by passing through the cold shield; The fuel gas is subjected to secondary temperature control by passing through the low-temperature copper block, and is in a liquefied state when flowing to the cryogenic target and infiltrates the double cone in the cryogenic target; The liquid helium gas is introduced from the intake valve to the cryogenic target holder, increases the gas pressure in the cryogenic target, and lowers the temperature of the fuel gas, thereby achieving tertiary temperature control and solidifying the fuel gas; The fuel gas is introduced from the fuel gas tank to the top intake valve of the low-temperature vacuum platform through a high-precision flow meter and an absolute pressure sensor; The top intake valve steel pipe passes through the top through hole of the cold shield cavity for primary temperature control of the target pellet gas; Then, the target pellet gas hose is connected through the polyimide target pellet gas hose, and the target pellet gas hose is close to the low-temperature copper block for secondary temperature control of the target pellet gas, and the fuel gas infiltrates the double cone in the cryogenic target in a liquefied state; The liquid helium is introduced from the liquid helium tank to the intake valve inside the low-temperature vacuum platform through a high-precision flow meter and a high-precision diaphragm gauge, and then connected through the liquid helium gas hose, and input to the double cone in the cryogenic target, thereby lowering the temperature of the liquefied gas and achieving tertiary temperature control.

2. The method of claim 1, wherein the vacuum low temperature platform is a freeze target puck inflation and freezing method, further comprising: The fuel gas is one of deuterium gas, tritium gas, and hydrogen gas, or a mixture of deuterium gas, tritium gas, and hydrogen gas.

3. The method for gas-filling and freezing frozen target pellets on a vacuum cryogenic platform according to claim 2, characterized in that, The performance indicators of the high-precision flow meter include: gas flow control range of 0-5 mL / min, and accuracy of ±1% FS; The performance indicators of the absolute pressure sensor include: a range of 0-1.6x10 5 Pa, and an accuracy of 0.01% FS; The performance index of the high-precision thin-film gauge includes: a range of 10-1x10 5 Pa, and a precision of 0.15% FS.

4. The method of claim 2, wherein the target pellets are frozen in the vacuum cryogenic platform. The temperature of the cold shield is 50k, and the temperature of the low-temperature copper block is 5-20k.

5. A vacuum cryogenic platform for use in a vacuum cryogenic platform based gassing and freezing method of a frozen target pellet according to any one of claims 1 to 4, characterized in that Comprising: A vacuum cover is located in the outer layer, provides mechanical shape and physical support for the vacuum low-temperature platform, and the internal space constitutes a vacuum cover cavity; A vacuum pump is connected to the vacuum cover, provides a pure environment and vacuum insulation for the vacuum cover cavity; A cold shield is located in the inner layer of the vacuum cover, blocks the room temperature environment outside the vacuum pump, and the internal space constitutes a cold shield cavity, which provides primary temperature control for the target pellet gas; The vacuum cover and the cold shield are provided with detachable flanges, intake valves, and detachable cavities, and the detachable cavities are provided with an observation window of the cryogenic target holder; A low-temperature copper block is located in the cold shield; A target holder clamp is fixed to the side wall of the low-temperature copper block at one end, and is used to clamp the cryogenic target holder and conduct the temperature of the low-temperature copper block to the cryogenic target holder, thereby providing primary temperature control; The connecting hose guides the input gas from the intake valve to the cryogenic target holder, and at least one connecting hose passes through the low-temperature copper block.

6. A vacuum cryogenic stage according to claim 5, wherein, The target holder clamp is a copper clamp or a gold-plated copper clamp, one end of which is threadedly fastened to the low-temperature copper block, and the other end of which directly clamps the cryogenic target holder.

7. The vacuum cryogenic stage of claim 5, wherein, The observation window is located on the right detachable cavity, and the window diameter is 1-5 inches, which is located at the top, front, and rear, respectively, for microscope imaging window, X-ray phase imaging, and infrared homogenization observation.

8. The vacuum cryogenic stage of claim 5, wherein, The detachable flanges include two types, one is a detachable flange for installing the vacuum cover and the cold shield, which is installed at the top or the bottom of the vacuum cover, and the other is a detachable flange for installing the detachable cavity, which is installed on the right side of the vacuum cover. The gas inlet valve includes two kinds, one is a target pellet gas inlet valve, which is installed on the top of the vacuum cover, and if there is a detachable flange on the top, it is installed on the detachable flange of the top; the other is a liquid helium inlet valve, which is connected with the existing refrigeration system and installed on the side of the vacuum cover.

9. The vacuum cryogenic stage of claim 5, wherein, The connecting hose is selected from a polyimide hose, and the winding number and winding distance of the low-temperature copper block are adjusted according to the results obtained by the observation window during the freezing process.

Images