Evaporation chamber for dilution refrigerator and manufacturing method thereof

Abstract

The invention discloses an evaporation chamber for a dilution refrigerator and a manufacturing method of the evaporation chamber, and relates to the field of refrigeration and low-temperature engineering. The evaporation chamber comprises an evaporation chamber cavity, and the upper end face of the evaporation chamber cavity and the lower end face of a cover plate flange are kept flush and welded through a welding point A; and the upper end face of the boss structure arranged at the top of the cover plate flange is flush with the lower end face of the superfluid helium thin film suppressor sleeve and is welded through a D welding point. The efficient and stable evaporation process in the evaporation chamber is achieved through different surface treatments of all parts of the evaporation chamber and the design of the reinforced annular heat exchange fins; the temperature-controllable nanoscale knife edge is used in cooperation with the superfluid helium suppressor cavity with the micropore flow guide structure to achieve heating suppression of the superfluid helium film, the whole dilution refrigeration cycle is stabilized, and operation of a high-performance and high-efficiency dilution refrigerator is maintained. The heat leakage loss of the whole evaporation chamber is fully reduced through the inhibition of the superfluid helium film, the use of materials with different thermal conductivities and the surface zoning treatment of the materials.

Description

Technical Field

[0001] The present invention relates to the field of refrigeration and cryogenic engineering, and particularly to an evaporation chamber for a dilution refrigerator and a manufacturing method thereof. Background Art

[0002] Dilution refrigerators are currently a research hotspot for cryogenic refrigerators in the extremely low temperature field. Due to their advantages of continuous refrigeration at a temperature of 100 mK, no electromagnetic interference, and low vibration, they have broad application prospects in fields such as superconducting quantum computing. The mK-temperature range dilution refrigerator uses a helium-3 / helium-4 mixed working fluid, and the lowest temperature can reach about 1 mK. The entire dilution refrigeration cycle includes precooling, throttling, condensation heat exchange, dilution process, reflux heat exchange, evaporation process, and compression process. The cycle is driven by an evaporation chamber and a pump group. Since the mixed working fluid contains helium-4, its liquid will form superfluid helium after the temperature is lower than 2.17 K, which has the characteristics of anti-gravity climbing and quickly passing through microporous structures, having a great negative impact on the dilution refrigeration cycle. Therefore, it is necessary to suppress superfluid helium to prevent it from entering the circulation loop.

[0003] The evaporation chamber of a dilution refrigerator is an important driver of the entire dilution refrigeration cycle. Ideally, it should achieve the following three functions:

[0004] (1) Achieve an efficient and stable evaporation process. In the actual operation process, an external heater needs to be connected to the lower surface of the evaporation chamber cavity of the dilution refrigerator to maintain its temperature at about 0.7 K. At this temperature, the evaporation rate is relatively fast, which can better drive the entire dilution refrigeration cycle. However, in fact, it is the mixed liquid in the evaporation chamber cavity that needs to be heated. Therefore, it is required that there is a heat transfer enhancement structure between the inner wall of the evaporation chamber cavity and the mixed liquid.

[0005] (2) Achieve the suppression of the superfluid helium film. The evaporation chamber of a dilution refrigerator is the place where the gas-liquid phase change process of the entire dilution refrigeration cycle is the most intense, with the largest gas-liquid interface. Helium-4 in the low-temperature mixed fluid is in a superfluid state at this temperature and has the property of anti-gravity climbing. Therefore, it will climb along the wall of the evaporation chamber to the outlet air duct of the evaporation chamber and finally enter the entire dilution refrigeration cycle under the action of pressure and temperature. However, this will affect the dilution refrigeration cycle, resulting in a decrease in the lowest temperature and refrigeration power, and affecting the balance of the entire dilution refrigeration cycle. Therefore, it is necessary to suppress the superfluid helium film to ensure that the concentration of helium-3 in the gas entering the dilution refrigeration cycle remains in a relatively high range (greater than 95%). This requires integrating a superfluid helium film suppressor in the evaporation chamber.

[0006] (3) Have a small heat leakage loss. The refrigeration capacity in the extremely low temperature region is often on the order of mW, and it is greatly affected by radiation heat leakage and superfluid helium heat conduction leakage. Therefore, it is required that the radiation heat leakage of the evaporation chamber cavity itself be reduced to the lowest.

[0007] In the evaporation chamber of a conventional dilution refrigerator at present, only a single knife-edge tip structure and a small-hole structure are used to achieve the suppression effect of the superfluid helium film. The overall suppression effect of its structure is not obvious, and it can only achieve a certain suppression effect at the initial stage of operation. This leads to a large amount of heat leakage loss in the evaporation chamber after the suppression effect of the superfluid helium film fails, and the content of helium-4 in the circulating gas increases, affecting the overall temperature stability and refrigeration performance of the dilution refrigerator. At the same time, generally, the inner wall surface of the evaporation chamber cavity is not subjected to partition surface treatment. Therefore, the conventional evaporation chamber has great limitations in meeting the three requirements of achieving an efficient and stable evaporation process, achieving the suppression of the superfluid helium film, and reducing heat leakage loss.

[0008] Therefore, it is necessary to invent an evaporation chamber for a dilution refrigerator and its manufacturing method to solve the above problems. Summary of the Invention

[0009] The purpose of the present invention is to provide an evaporation chamber for a dilution refrigerator and its manufacturing method to solve the problems in the background technology that in the evaporation chamber of a conventional dilution refrigerator, only a single knife-edge tip structure and a small-hole structure are used to achieve the suppression effect of the superfluid helium film. The overall suppression effect of its structure is not obvious, and it can only achieve a certain suppression effect at the initial stage of operation. This leads to a large amount of heat leakage loss in the evaporation chamber after the suppression effect of the superfluid helium film fails, and the content of helium-4 in the circulating gas increases, affecting the overall temperature stability and refrigeration performance of the dilution refrigerator. At the same time, generally, the inner wall surface of the evaporation chamber cavity is not subjected to partition surface treatment. Therefore, the conventional evaporation chamber has great limitations in meeting the three requirements of achieving an efficient and stable evaporation process, achieving the suppression of the superfluid helium film, and reducing heat leakage loss.

[0010] To achieve the above purpose, the present invention provides the following technical solution: An evaporation chamber for a dilution refrigerator includes an evaporation chamber cavity. The upper end surface of the evaporation chamber cavity is flush with the lower end surface of the cover flange and is welded through welding point A. The upper end surface of the boss structure provided on the top of the cover flange is flush with the lower end surface of the superfluid helium film suppressor sleeve and is welded through welding point D. The upper end surface of the superfluid helium film suppressor sleeve flange structure is flush with the lower end surface of the temperature control knife-edge flange structure and is welded through welding point C. The upper end surface of the temperature control knife-edge flange structure is flush with the lower end surface of the evaporation chamber outlet airway flange structure and is welded through welding point B. The table surface of the boss structure at the lower end of the evaporation chamber outlet airway is flush with the upper end surface of the condensation baffle flange structure. The lower end surface of the condensation baffle flange structure is flush with the upper end surface of the baffle fixing sleeve. And the evaporation chamber outlet airway, the condensation baffle, and the baffle fixing sleeve are welded through welding point E.

[0011] Preferably, an evaporation chamber cavity side wall is provided inside the evaporation chamber cavity. At the bottom of the evaporation chamber cavity inside the evaporation chamber cavity, three evenly distributed annular heat exchange fins are cut out, and the height of the annular heat exchange fins is one-half of the total height of the evaporation chamber cavity, strengthening the convective heat transfer inside the evaporation chamber cavity. A reflux port is provided at the bottom of the evaporation chamber cavity. The evaporation chamber cavity and the annular heat exchange fins are integrally processed and formed to ensure good heat exchange between the annular heat exchange fins and the evaporation chamber cavity.

[0012] Preferably, the upper end face of the cover flange, the inner surface of the superfluid helium film suppressor sleeve, the temperature control knife edge, and the outer surface of the evaporation chamber outlet airway tube structure together form a superfluid helium suppressor chamber, and there is an annular microchannel between the cover flange and the evaporation chamber outlet airway. The width of the channel is controlled below 0.05 mm, that is, the difference between the inner diameter of the cover flange and the outer diameter of the tube structure part of the evaporation chamber outlet airway does not exceed 0.05 mm. The two use the same material to ensure that the deformation amounts are maintained consistent under the same temperature condition, and a 1 mm rounded corner diversion structure is processed at the inlet of the channel to enable the superfluid helium film to quickly enter the superfluid helium suppressor chamber along the diversion structure.

[0013] Preferably, the length of the middle knife edge of the temperature control knife edge is one-half of the height of the superfluid helium film suppressor sleeve, and the temperature control knife edge structure is integrally formed, and the end of the temperature control knife edge is a nano-level knife edge structure.

[0014] Preferably, the thickness of the condensation baffle decreases from the inside to the outside, and the condensation baffle is integrally in a conical surface structure.

[0015] The present invention also provides a manufacturing method for an evaporation chamber for a dilution refrigerator, using the above-mentioned evaporation chamber for a dilution refrigerator. The specific operation steps are as follows:

[0016] Step 1: Weld the A welding point, B welding point, C welding point, D welding point, and E welding point along a circle using the clean brazing technology to combine the evaporation chamber cavity, the cover flange, the superfluid helium film suppressor sleeve, the temperature control knife edge, the evaporation chamber outlet airway, the condensation baffle, and the baffle fixing sleeve into a whole, thereby forming an evaporation chamber for a dilution refrigerator;

[0017] Step 2: The surface roughness requirement of the outer surface of the evaporation chamber cavity is lower than 0.04, which is beneficial to reducing the emissivity and minimizing the radiative heat leakage. The surface roughness requirement of the bottom surface of the evaporation chamber cavity is higher than 0.8, and the surface roughness requirement of the annular fins is higher than 0.8. The surface roughness setting of this part of the structure is beneficial to the formation of condensation nuclei of the liquid inside the evaporation chamber cavity, and is more conducive to the gas-liquid phase change process and the evaporation of gas. The surface roughness requirement of the side wall of the evaporation chamber cavity is lower than 0.04, and the surface roughness setting of this part of the structure is beneficial to initially realizing the suppression of the superfluid helium film;

[0018] Step 3: The cover flange is made of a material with low thermal conductivity and is made of the same material as the evaporation chamber outlet air duct. The difference between the inner diameter of the cover flange and the outer diameter of the pipe structure part of the evaporation chamber outlet air duct is controlled within 0.05 mm. The upper and lower end faces, inner diameter surface, and fillet flow guiding structure surface of the cover flange are subjected to electrolytic polishing treatment, and the inner diameter surface and fillet flow guiding structure are gold-plated, which is conducive to initially suppressing the superfluid helium film. The surface roughness requirement of the outer surface of the cover flange is less than 0.04, reducing the emissivity and minimizing the radiative heat leakage;

[0019] Step 4: The superfluid helium film suppressor sleeve is made of a material with low thermal conductivity. The thickness of the pipe structure part of the superfluid helium film suppressor sleeve is controlled between 1 and 2 mm, having a certain structural strength and minimizing the heat transfer up and down as much as possible. The inner wall of the pipe structure of the superfluid helium film suppressor sleeve is subjected to electrolytic polishing treatment, and the outer wall roughness requirement is less than 0.04;

[0020] Step 5: The temperature-controlled knife edge is made of a material with high thermal conductivity. A heating sheet and heating wire can be added to the plane of the temperature-controlled knife edge flange, and temperature control is achieved through an external controller. The tip of the temperature-controlled knife edge is a nanoscale knife edge structure, which itself has the effect of suppressing the superfluid helium film;

[0021] Step 6: The inner diameter of the evaporation chamber outlet air duct is controlled between 10 and 16 mm and is made of a material with low thermal conductivity. The thickness of the pipe structure part of the evaporation chamber outlet air duct is controlled below 1 mm, which can avoid being affected by the heating of the temperature-controlled knife edge at low temperatures. Both the inner and outer surfaces of the pipe structure part of the evaporation chamber outlet air duct are subjected to electrolytic polishing treatment and need to be gold-plated;

[0022] Step 7: The condensation baffle decreases in thickness from the inside to the outside and has an overall conical surface structure with a conical angle of 15°. The maximum diameter of the condensation baffle is less than the inner diameter of the evaporation chamber cavity by more than 5 mm. The entire surface of the condensation baffle is subjected to electrolytic polishing treatment.

[0023] In the above technical solutions, the technical effects and advantages provided by the present invention are as follows:

[0024] 1. Through different surface treatments of the components in the evaporation chamber and the design of the enhanced annular heat exchange fins, an efficient and stable evaporation process in the evaporation chamber is achieved;

[0025] 2. Using a temperature-controllable nanoscale knife edge and cooperating with the superfluid helium suppressor chamber with a microporous flow guiding structure realizes the heating suppression of the superfluid helium film, which is beneficial to stabilizing the entire dilution refrigeration cycle and maintaining the operation of a high-performance and high-efficiency dilution refrigerator;

[0026] 3. Through the suppression of the superfluid helium film, the use of materials with different thermal conductivities, and the surface zoning treatment of the materials, the heat leakage loss of the entire evaporation chamber is fully reduced. Description of the Drawings

[0027] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings.

[0028] Figure 1 It is the overall three-dimensional structural decomposition diagram of the evaporation chamber for the dilution refrigerator of the present invention;

[0029] Figure 2 It is the overall structural sectional view of the evaporation chamber for the dilution refrigerator of the present invention;

[0030] Figure 3 It is the three-dimensional schematic diagram of the evaporation chamber cavity of the present invention;

[0031] Figure 4 For the present invention Figure 2 The enlarged plan view of the structure at position A.

[0032] Explanation of reference numerals:

[0033] 1. Evaporation chamber cavity; 2. Return port; 3. Bottom of the evaporation chamber cavity; 4. Annular heat exchange fins; 5. Side wall of the evaporation chamber cavity; 6. Welding point A; 7. Cover flange; 8. Superfluid helium film suppressor sleeve; 9. Temperature control knife edge; 10. Evaporation chamber outlet air duct; 11. Welding point B; 12. Welding point C; 13. Superfluid helium suppressor chamber; 14. Welding point D; 15. Welding point E; 16. Condensation baffle; 17. Baffle fixing sleeve. Detailed implementation manners

[0034] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the following will further introduce the present invention in detail in conjunction with the drawings.

[0035] The present invention provides as Figures 1-4An evaporation chamber for a dilution refrigerator as shown, comprising an evaporation chamber cavity 1. The upper end face of the evaporation chamber cavity 1 is flush with the lower end face of the cover flange 7 and is welded through the A welding point 6. Moreover, the upper end face of the boss structure provided on the top of the cover flange 7 is flush with the lower end face of the superfluid helium film suppressor sleeve 8 and is welded through the D welding point 14. And the upper end face of the flange structure of the superfluid helium film suppressor sleeve 8 is flush with the lower end face of the flange structure of the temperature control knife edge 9 and is welded through the C welding point 12. The upper end face of the flange structure of the temperature control knife edge 9 is flush with the lower end face of the flange structure of the evaporation chamber outlet airway 10 and is welded through the B welding point 11. And the table surface of the boss structure at the lower end of the evaporation chamber outlet airway 10 is flush with the upper end face of the flange structure of the condensation baffle 16. The lower end face of the flange structure of the condensation baffle 16 is flush with the upper end face of the baffle fixing sleeve 17. And the evaporation chamber outlet airway 10, the condensation baffle 16 and the baffle fixing sleeve 17 are welded through the E welding point 15. Thus, the evaporation chamber for a dilution refrigerator is composed of the evaporation chamber cavity 1, the cover flange 7, the superfluid helium film suppressor sleeve 8, the temperature control knife edge 9, the evaporation chamber outlet airway 10, the condensation baffle 16 and the baffle fixing sleeve 17.

[0036] An evaporation chamber side wall 5 is arranged inside the evaporation chamber cavity 1. At the bottom 3 of the evaporation chamber cavity 1 inside the evaporation chamber cavity 1, three uniform annular heat exchange fins 4 are cut out. And the height of the annular heat exchange fins 4 is one-half of the total height of the evaporation chamber cavity 1, strengthening the convective heat transfer inside the evaporation chamber cavity 1. A return port 2 is arranged at the bottom 3 of the evaporation chamber cavity 1. The evaporation chamber cavity 1 and the annular heat exchange fins 4 are integrally processed and formed, ensuring good heat exchange between the annular heat exchange fins 4 and the evaporation chamber cavity 1. By arranging the annular heat exchange fins 4 inside the evaporation chamber cavity 1, the convective heat transfer is strengthened, and the integration of the superfluid helium suppressor and the evaporation chamber is realized.

[0037] The upper end face of the cover flange 7, the inner surface of the superfluid helium film suppressor sleeve 8, the temperature control knife edge 9 and the outer surface of the tube structure of the evaporation chamber outlet airway 10 together constitute the superfluid helium suppressor chamber 13. And there is an annular microchannel between the cover flange 7 and the evaporation chamber outlet airway 10. The width of the channel is controlled at 0.04 mm. Both use the same material to ensure that the deformation amount remains consistent under the same temperature condition. And a 1 mm rounded corner diversion structure is processed at the inlet of the channel, enabling the superfluid helium film to quickly enter the superfluid helium suppressor chamber 13 along the diversion structure.

[0038] The length of the knife edge in the temperature control knife edge 9 is one-half of the height of the superfluid helium film suppressor sleeve 8. And the temperature control knife edge 9 is integrally formed. And the end of the temperature control knife edge 9 is a nanoscale knife edge structure. The temperature control knife edge 9 is used to heat the superfluid helium film to convert it into gas.

[0039] The condensation baffle 16 decreases in thickness from the inside to the outside, and the condensation baffle 16 as a whole has a conical surface structure. The temperature-controlled cutting edge 9 heats the superfluid helium film to convert it into gas, and then it condenses back into normal fluid liquid helium on the condensation baffle 16 again.

[0040] During use, the evaporation chamber for a dilution refrigerator, which consists of an evaporation chamber cavity 1, a cover flange 7, a superfluid helium film suppressor sleeve 8, a temperature-controlled cutting edge 9, an evaporation chamber outlet air duct 10, a condensation baffle 16, and a baffle fixing sleeve 17, realizes the diversion of the superfluid helium film in a way of annular micropores and annular rounded corner diversion. The temperature-controlled cutting edge 9 is used to heat the superfluid helium film to convert it into gas, and then it condenses back into normal fluid liquid helium on the condensation baffle 16 again. Finally, it flows back into the evaporation chamber cavity 1 under the action of gravity. And through the annular heat exchange fins 4 arranged in the evaporation chamber cavity 1, the convective heat transfer is strengthened, realizing the integration of the superfluid helium suppressor and the evaporation chamber.

[0041] The present invention also provides a manufacturing method for an evaporation chamber for a dilution refrigerator. Using the above evaporation chamber for a dilution refrigerator, the specific operation steps are as follows:

[0042] Step 1: The A welding point 6, B welding point 11, C welding point 12, D welding point 14, and E welding point 15 are all welded along a circumference using a clean brazing technique to combine the evaporation chamber cavity 1, the cover flange 7, the superfluid helium film suppressor sleeve 8, the temperature-controlled cutting edge 9, the evaporation chamber outlet air duct 10, the condensation baffle 16, and the baffle fixing sleeve 17 into a whole, thus forming an evaporation chamber for a dilution refrigerator;

[0043] Step 2: The height of the evaporation chamber cavity 1 is controlled at 80 mm, the aspect ratio is 2:3, the number of uniform annular heat exchange fins 4 is 3, the distance between the annular heat exchange fins 4 is controlled at 11 mm, the diameter of the bottom return port 2 is controlled at 5.5 mm, the surface roughness requirement of the outer surface of the evaporation chamber cavity 1 is 0.03, which is beneficial to reducing the emissivity and decreasing the radiation heat leakage. The surface roughness requirement of the bottom surface 3 of the evaporation chamber cavity is a frosted surface with a roughness of 0.9, and the surface roughness requirement of the annular fin surface is a frosted surface with a roughness of 0.9. The surface roughness setting of this part of the structure is beneficial to forming condensation nuclei of the liquid in the evaporation chamber cavity 1, and is more beneficial to the gas-liquid phase change process and the evaporation of gas. The surface roughness requirement of the side wall 5 of the evaporation chamber cavity is a surface with an electroplated and polished treatment with a roughness of 0.04. The surface roughness setting of this part of the structure is beneficial to initially realizing the suppression of the superfluid helium film;

[0044] Step 3: The cover flange 7 is made of a material with low thermal conductivity and is made of the same material as the evaporation chamber outlet air duct 10. The difference between the inner diameter of the cover flange 7 and the outer diameter of the pipe structure part of the evaporation chamber outlet air duct 10 is controlled within 0.05 mm. The upper and lower end faces, inner diameter surface, and rounded corner diversion structure surface of the cover flange 7 are subjected to electrolytic polishing treatment, and the inner diameter surface and rounded corner diversion structure are gold-plated, which is conducive to initially realizing the suppression of the superfluid helium film. The surface roughness of the outer surface of the cover flange 7 is required to be 0.03, reducing the emissivity and minimizing the radiative heat leakage;

[0045] Step 4: The superfluid helium film suppressor sleeve 8 is made of a material with low thermal conductivity. The thickness of the pipe structure part of the superfluid helium film suppressor sleeve 8 is controlled at 1.5 mm, which has a certain structural strength and minimizes the heat transfer up and down as much as possible. The inner wall of the pipe structure of the superfluid helium film suppressor sleeve 8 is subjected to electrolytic polishing treatment, and the outer wall roughness requirement is 0.03;

[0046] Step 5: The temperature-controlled knife edge 9 is made of a material with high thermal conductivity. A heating sheet and heating wire can be added to the flange plane of the temperature-controlled knife edge 9, and temperature control is achieved through an external controller. The tip of the knife edge of the temperature-controlled knife edge 9 has a nano-level knife edge structure, which itself has the effect of suppressing the superfluid helium film;

[0047] Step 6: The inner diameter of the evaporation chamber outlet air duct 10 is controlled at 11 mm and is made of a material with low thermal conductivity. The thickness of the pipe structure part of the evaporation chamber outlet air duct 10 is controlled at 0.9 mm, which can avoid being affected by the heating of the temperature-controlled knife edge 9 at low temperatures. The inner and outer surfaces of the pipe structure part of the evaporation chamber outlet air duct 10 are both subjected to electrolytic polishing treatment and need to be gold-plated;

[0048] Step 7: The condensation baffle 16 decreases in thickness from the inside to the outside and has an overall conical surface structure with a conical angle of 15°. The maximum diameter is less than the inner diameter of the evaporation chamber cavity 1 by 6 mm. The entire surface of the condensation baffle 16 is subjected to electrolytic polishing treatment.

[0049] Only some exemplary embodiments of the present invention have been described by way of illustration above. Undoubtedly, for those of ordinary skill in the art, the described embodiments can be modified in various different ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the protection scope of the claims of the present invention.

Claims

1. An evaporation chamber for a dilution refrigerator, comprising an evaporation chamber cavity (1), characterized in that, The upper end surface of the evaporation chamber cavity (1) and the lower end surface of the cover flange (7) are kept flush and welded through the A welding point (6). The upper end surface of the boss structure provided at the top of the cover flange (7) is kept flush with the lower end surface of the superfluid helium film suppressor sleeve (8) and welded through the D welding point (14). Also, the upper end surface of the flange structure of the superfluid helium film suppressor sleeve (8) and the lower end surface of the flange structure of the temperature control knife edge (9) are kept flush and welded through the C welding point (12). The upper end surface of the flange structure of the temperature control knife edge (9) and the lower end surface of the flange structure of the evaporation chamber outlet airway (10) are kept flush and welded through the B welding point (11). The table surface of the lower boss structure of the evaporation chamber outlet airway (10) is kept flush with the upper end surface of the flange structure of the condensation baffle (16). The lower end surface of the flange structure of the condensation baffle (16) is kept flush with the upper end surface of the baffle fixing sleeve (17). And the evaporation chamber outlet airway (10), the condensation baffle (16), and the baffle fixing sleeve (17) are welded through the E welding point (15).

2. The evaporation chamber for a dilution refrigerator according to claim 1, characterized in that An evaporation chamber cavity side wall (5) is provided inside the evaporation chamber cavity (1). At the evaporation chamber cavity bottom (3) inside the evaporation chamber cavity (1), three uniform annular heat exchange fins (4) are cut out, and the height of the annular heat exchange fins (4) is one-half of the total height of the evaporation chamber cavity (1). A reflux port (2) is provided at the evaporation chamber cavity bottom (3).

3. The evaporation chamber for dilution refrigerator according to claim 1, characterized in that, The upper end surface of the cover flange (7), the inner surface of the superfluid helium film suppressor sleeve (8), the temperature control knife edge (9), and the outer surface of the pipe structure of the evaporation chamber outlet airway (10) together form a superfluid helium suppressor chamber (13). There is an annular microchannel flow path between the cover flange (7) and the evaporation chamber outlet airway (10), and a 1 mm rounded corner flow guiding structure is machined at the inlet of the flow path.

4. The evaporation chamber for a dilution refrigerator according to claim 3, characterized in that, The length of the knife edge in the temperature control knife edge (9) is one-half of the height of the superfluid helium film suppressor sleeve (8). The temperature control knife edge (9) is integrally formed, and the end of the temperature control knife edge (9) is a nano-level knife edge structure.

5. The evaporation chamber for dilution refrigerator according to claim 1, characterized in that, The condensation baffle (16) decreases in thickness from the inside to the outside, and the condensation baffle (16) is overall in a conical surface structure.

6. A manufacturing method of an evaporation chamber for a dilution refrigerator, using an evaporation chamber for a dilution refrigerator as described in any one of claims 1-5, characterized in that, The specific operation steps are as follows: Step 1: The A welding point (6), B welding point (11), C welding point (12), D welding point (14), and E welding point (15) are all welded along a circle using the clean brazing technology to combine the evaporation chamber cavity (1), the cover flange (7), the superfluid helium film suppressor sleeve (8), the temperature control knife edge (9), the evaporation chamber outlet airway (10), the condensation baffle (16), and the baffle fixing sleeve (17) into a whole, thereby forming an evaporation chamber for a dilution refrigerator; Step 2: The rough surface structure on the outer surface of the evaporation chamber cavity (1) is beneficial to reducing the emissivity and decreasing the radiative heat leakage. The bottom surface (3) of the evaporation chamber cavity and the surfaces of the annular fin structures are both provided with rough structures. The rough setting of these parts of the structure is conducive to the formation of condensation nuclei of the liquid in the evaporation chamber cavity (1), and is more conducive to the gas-liquid phase change process and the evaporation of the gas. The rough surface structure on the side wall (5) of the evaporation chamber cavity is conducive to initially suppressing the superfluid helium film; Step 3: The cover flange (7) is made of a material with low thermal conductivity. The cover flange (7) and the evaporation chamber outlet airway (10) are made of the same material. The upper and lower end faces, the inner diameter surface and the surface of the fillet flow guiding structure of the cover flange (7) are subjected to electrolytic polishing treatment. The inner diameter surface and the fillet flow guiding structure of the cover flange (7) are gold-plated to achieve the suppression of the superfluid helium film. The outer surface of the cover flange (7) is provided with a rough structure, which can reduce the emissivity and decrease the radiative heat leakage; Step 4: The superfluid helium film suppressor sleeve (8) is made of a material with low thermal conductivity, and the inner wall of the superfluid helium film suppressor sleeve (8) is subjected to electrolytic polishing treatment; Step 5: The temperature control knife edge (9) is made of a material with high thermal conductivity. A heating sheet and heating wires can be added to the flange plane of the temperature control knife edge (9), and temperature control is realized through an external controller. The tip of the temperature control knife edge (9) is a nano-level knife edge structure, which itself has the effect of suppressing the superfluid helium film; Step 6: The evaporation chamber outlet airway (10) is made of a material with low thermal conductivity. Both the inner and outer surfaces of the structural part of the evaporation chamber outlet airway (10) are subjected to electrolytic polishing treatment and need to be gold-plated; Step 7: The condensation baffle (16) decreases in thickness from the inside to the outside, and is in an overall conical surface structure with a conical angle of 15°. The maximum diameter of the condensation baffle (16) is smaller than the inner diameter of the evaporation chamber cavity (1), and the entire surface of the condensation baffle (16) is subjected to electrolytic polishing treatment.

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