Blackbody radiation shielding device suitable for ultrahigh vacuum environment

Abstract

The invention discloses a blackbody radiation shielding device suitable for an ultrahigh vacuum environment, and the device comprises an annular cavity, the circumferential direction of the annular cavity is provided with a pair of atomic beam inlets and outlets and five pairs of optical windows, the bottom of the annular cavity is provided with a cavity bottom plate, the top of the annular cavity is provided with a cavity cover, and the cavity cover and the cavity bottom plate are respectively provided with an optical window. The flange plate tightly presses the C-shaped heat conducting plate provided with the platinum resistance probe on the lower surface of the cavity bottom plate and is fixedly connected with the cavity bottom plate, and the water-cooling MOT coil tightly presses the semiconductor chilling plate on the lower surface of the flange plate and is fixedly connected with the flange plate. According to the invention, the platinum resistor is fixed outside the vacuum and can be detached at any time for secondary calibration, the influence of the vacuum baking process on the platinum resistor is eliminated, and the temperature measurement precision is improved; active temperature control is performed in the shielding cavity through the semiconductor chilling plate and the C-shaped heat conduction plate, temperature fluctuation in the cavity is reduced, and the uncertainty of the frequency of the atomic optical clock caused by black body radiation frequency shift is remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of atomic optical frequency standards, and more specifically to a blackbody radiation shielding device suitable for ultra-high vacuum environments. Background Technology

[0002] Optical atomic clocks utilize the narrow linewidth transitions of atoms in the optical band as a frequency reference, exhibiting frequency stability and uncertainty far exceeding that of traditional microwave clocks, and are expected to become the next-generation time and frequency standard. Blackbody radiation (BBR) frequency shift is the primary source of uncertainty in optical clock systems. For most optical clock systems, the contribution of blackbody radiation frequency shift dominates the system uncertainty assessment table, and is the main obstacle limiting optical clock uncertainty to the E-19 order of magnitude. Therefore, precise control and characterization of blackbody radiation frequency shift is a key technology for realizing high-precision atomic optical clocks.

[0003] The blackbody radiation frequency shift of atomic clock transitions is caused by the thermal radiation field surrounding the atoms and is closely related to the temperature fluctuations and temperature gradients of the radiation field. In order to evaluate the impact of the thermal radiation field on optical clocks, it is necessary to precisely control the ambient temperature of the experimental setup at room temperature to improve the blackbody radiation frequency shift of the optical clock.

[0004] To achieve precise control and characterization of blackbody radiation frequency shift, three main technical approaches are currently employed: The first approach involves overall temperature control and multi-point temperature monitoring within the vacuum cavity, aided by finite element thermal radiation analysis. This approach requires precise control of the overall system temperature to reduce temperature non-uniformity within the vacuum cavity, typically achieved using precision water cooling devices or precision air conditioning systems, resulting in a complex overall structure. The second approach utilizes cryogenic technology, designing a cryogenic cavity within the vacuum and transferring atoms into it using moving optical lattice technology, or directly cooling and confining atoms within the cryogenic cavity, thereby significantly reducing the blackbody radiation frequency shift and its uncertainty. While this approach is the most effective, the complex design of the cryogenic structure within the vacuum and the need for expensive cryogenic cycling equipment hinder the portability and miniaturization of optical clocks. The third approach employs a vacuum-based blackbody radiation shielding cavity scheme, which achieves a uniform thermal radiation environment by placing a high thermal conductivity blackbody radiation shielding cavity within the vacuum. Since the blackbody radiation shielding cavity is located in a vacuum, it is not sensitive to ambient temperature and airflow. This greatly reduces the requirements for temperature control of the vacuum system. However, it usually requires multiple sets of platinum resistance thermometers to be arranged on the outer surface of the shielding cavity to measure the temperature inside the cavity, which makes the vacuum system more complex. In addition, the baking process during vacuum preparation will affect the temperature measurement accuracy of the platinum resistance thermometers, thus limiting the control accuracy of the blackbody radiation frequency shift. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a blackbody radiation shielding device suitable for ultra-high vacuum environments. This device employs an embedded blackbody radiation shielding cavity design, making it suitable for ultra-high vacuum environments. Furthermore, it allows for precise temperature measurement and control within the vacuum cavity from the air end, meeting the requirements of ultra-high vacuum applications at the E-9 Pa level for optical clocks.

[0006] The above-mentioned objectives of the present invention are achieved by the following technical means: A blackbody radiation shielding device suitable for ultra-high vacuum environments includes an annular cavity. The annular cavity has one pair of atomic beam inlets and outlets and five pairs of optical windows arranged circumferentially. A cavity base plate is provided at the bottom of the annular cavity, and a cavity cover is provided at the top of the annular cavity. Optical windows are respectively provided on the cavity cover and the cavity base plate. The central axes of the atomic beam inlets and outlets, the central axes of the pairs of optical windows arranged circumferentially in the annular cavity, and the central axes of the pairs of optical windows arranged vertically in the annular cavity all pass through the center of the annular cavity. The central axis of one of the pairs of optical windows arranged circumferentially in the annular cavity is perpendicular to the central axis of the atomic beam inlets and outlets. A temperature control and measurement component is fixedly provided on the lower surface of the cavity base plate, and a water-cooled MOT coil is fixedly provided below the temperature control and measurement component.

[0007] The temperature control and measurement components include a C-shaped heat-conducting plate, a flange, a platinum resistance probe, and a thermoelectric cooler. Screw No. 2 passes through the annular cavity and the C-shaped heat-conducting plate from top to bottom, securing the C-shaped heat-conducting plate to the lower surface of the cavity base plate. Screw No. 3 passes through the flange and the C-shaped heat-conducting plate from bottom to top, pre-tightening the flange to the lower surface of the C-shaped heat-conducting plate. The C-shaped heat-conducting plate and the flange are fixed by welding. The C-shaped heat-conducting plate has a probe mounting hole. The platinum resistance probe passes through the through hole on the flange and is fixed in the probe mounting hole. The thermoelectric cooler is fixed to the upper surface of the water-cooled MOT coil with thermally conductive epoxy resin. The water-cooled MOT coil presses the upper surface of the thermoelectric cooler against the lower surface of the flange and is fixedly connected to the flange.

[0008] The semiconductor refrigeration chips are multiple, with two semiconductor refrigeration chips connected in series to form a refrigeration unit, and each refrigeration unit connected in parallel. The semiconductor refrigeration chips are evenly and symmetrically distributed around the central axis of the annular cavity.

[0009] The platinum resistance probe includes a platinum resistance resistor and an oxygen-free copper screw. The platinum resistance resistor is soldered to the end face of the oxygen-free copper screw via an indium layer, and the oxygen-free copper screw is threadedly connected to the probe mounting hole.

[0010] The probe mounting hole is a blind hole, and a thermally conductive thin wall is formed between the bottom of the probe mounting hole and the upper surface of the C-shaped heat-conducting plate.

[0011] The atomic beam inlet and outlet are the atomic beam inlet and outlet channels, respectively. The circumferentially arranged optical window pairs of the annular cavity are the first and sixth flat windows, the second and seventh flat windows, the third and eighth flat windows, the fourth and ninth flat windows, and the fifth and tenth flat windows. The vertically arranged optical window pairs of the annular cavity are the eleventh and twelfth flat windows. The first to tenth flat windows are pressed onto the annular cavity by window retaining rings, and the retaining rings pressing the first to tenth flat windows are fixed onto the annular cavity by screw No. 1. The eleventh flat window is pressed onto the cavity bottom plate by a window retaining ring, and the retaining ring pressing the eleventh flat window is fixed onto the cavity bottom plate by screw No. 1. The twelfth flat window is pressed onto the cavity cover by a window retaining ring, and the retaining ring pressing the twelfth flat window is fixed onto the cavity cover by screw No. 1.

[0012] The materials of screws No. 1, No. 2 and No. 3 are all TC4 titanium alloy. Screws No. 1, No. 2 and No. 3 have screw through holes from the nut to the screw tip. The screw hole on the annular cavity that is adapted to connect with screw No. 1 is a blind hole.

[0013] The annular cavity, cavity cover, cavity bottom plate, C-shaped heat-conducting plate, window retaining ring set on the cavity cover, and window retaining ring set on the cavity bottom plate are all provided with gaps in the same radial direction.

[0014] The annular cavity, cavity base plate, cavity cover, C-shaped heat-conducting plate, atomic beam inlet channel, and atomic beam outlet channel are all made of oxygen-free copper. The inner surfaces of the annular cavity, cavity base plate, cavity cover, atomic beam inlet channel, atomic beam outlet channel, and the two side plates and edge surfaces of the C-shaped heat-conducting plate are all covered with a conductive coating with a thermal radiation coefficient of 0.95. The inner surfaces of the first to twelfth flat windows are coated with an ITO antireflective film.

[0015] The conductive coating is made by thoroughly mixing multi-walled carbon nanotube powder with a purity greater than 99.9% with organosilicon resin at a mass ratio of 1:2.

[0016] Compared with the prior art, the present invention has the following advantages: (1) The platinum resistance thermometer used for temperature measurement is fixed outside the vacuum and can be disassembled at any time for secondary calibration. At the same time, the influence of the vacuum baking process on the platinum resistance thermometer is eliminated, which is conducive to improving the temperature measurement accuracy. (2) By adopting the method of accurately measuring the temperature inside the blackbody radiation shielding cavity from the air end, the external platinum resistance reduces the complexity of the blackbody radiation shielding cavity structure in the vacuum environment, improves the system reliability, and is conducive to the realization of ultra-high vacuum; (3) Active temperature control of the atomic thermal radiation environment of the blackbody radiation shielding cavity is achieved by using semiconductor cooling chips and temperature control and measurement components, which reduces the temperature fluctuation in the blackbody radiation shielding cavity and can significantly improve the frequency uncertainty of the atomic optical clock caused by the blackbody radiation frequency shift. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the structure of a blackbody radiation shielding cavity in a vacuum environment; Figure 3 This is an exploded view of the structure of the present invention; Figure 4 This is a schematic diagram of the installation of a platinum resistance probe; In the diagram: 1-Annular cavity; 2-Cavity cover; 3-C-type heat-conducting plate; 4-Flange; 501-Atomic beam inlet channel; 502-Atomic beam outlet channel; 601-612 are the first to twelfth flat windows respectively; 7-Window pressure ring; 8-Platinum resistance probe; 9-Semiconductor cooling chip; 10-Water-cooled MOT coil; 1001-Water-cooled inlet; 1002-Water-cooled outlet; 1101-Screw No. 1; 1102-Screw No. 2; 1103-Screw No. 3. Detailed Implementation

[0018] To facilitate understanding and implementation of the present invention by those skilled in the art, the present invention will be further described in detail below with reference to embodiments. The embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0019] Example 1: like Figures 1 to 3As shown, a blackbody radiation shielding device suitable for ultra-high vacuum environments includes a blackbody radiation shielding cavity, which comprises an annular cavity 1 and a cavity cover 2. The annular cavity 1 has one pair of atomic beam inlets / outlets and five pairs of optical windows arranged circumferentially. A cavity base plate is provided at the bottom of the annular cavity 1, and the cavity base plate is integrally formed with the annular cavity 1. This integral design of the cavity base plate and the annular cavity 1 provides better heat conduction compared to a separate design. The cavity cover 2 is provided at the top of the annular cavity 1. In this embodiment, the cavity cover 2 is fixed to the top of the annular cavity 1 by screw No. 1101. Optical windows are respectively provided on the cavity cover 2 and the cavity base plate. The central axes of the atomic beam inlets / outlets, the central axes of the circumferentially arranged optical windows of the annular cavity 1, and the central axes of the vertically arranged optical windows of the annular cavity 1 (the optical windows on the cavity cover 2 and the cavity base plate form a vertically arranged optical window pair) all pass through the center of the annular cavity 1. One pair of atomic beam inlets and outlets are used to form the entry and exit channels of the atomic beam. The optical window is used for laser cooling, lattice trapping and clock probing. In the experiment, the optical window can be flexibly selected as the observation window or optical channel as needed.

[0020] In some embodiments, the optical windows arranged circumferentially in the annular cavity 1 are aligned, wherein the central axis of one pair of optical windows is perpendicular to the central axis of the atomic beam inlet and outlet.

[0021] Furthermore, the atomic beam inlet and outlet are atomic beam inlet channel 501 and atomic beam outlet channel 502. The circumferentially arranged optical window pairs of the annular cavity 1 are the first flat window 601 and the sixth flat window 606, the second flat window 602 and the seventh flat window 607, the third flat window 603 and the eighth flat window 608, the fourth flat window 604 and the ninth flat window 609, and the fifth flat window 605 and the tenth flat window 610. The vertically arranged optical window pairs of the annular cavity 1 are the eleventh flat window 611 and the twelfth flat window 612. The first flat window 601 to the sixth flat window 606 are... Ten flat window panes 610 are pressed onto the annular cavity 1 by window pane retaining rings 7. The retaining rings 7 pressing the first flat window pane 601 to the tenth flat window pane 610 are fixed onto the annular cavity 1 by screw No. 1101. The eleventh flat window pane 611 is pressed onto the cavity bottom plate by window pane retaining rings 7. The retaining rings 7 pressing the eleventh flat window pane 611 are fixed onto the cavity bottom plate by screw No. 1101. The twelfth flat window pane 612 is pressed onto the cavity cover 2 by window pane retaining rings 7. The retaining rings 7 pressing the twelfth flat window pane 612 are fixed onto the cavity cover 2 by screw No. 1101.

[0022] In some embodiments, a blackbody radiation shielding device suitable for ultra-high vacuum environments further includes a temperature control and measurement component, which includes a C-shaped heat-conducting plate 3, a flange 4, a platinum resistance probe 8, and a semiconductor cooling chip 9. A screw 1102 passes through the annular cavity 1 and the C-shaped heat-conducting plate 3 from top to bottom, securing the C-shaped heat-conducting plate 3 to the lower surface of the cavity base plate; a screw 1103 passes through the flange 4 and the C-shaped heat-conducting plate 3 from bottom to top, pre-fastening the flange 4 to the lower surface of the C-shaped heat-conducting plate 3. The C-shaped heat-conducting plate 3 and the flange 4 are fixed by welding. The C-shaped heat-conducting plate 3 has a probe mounting hole. The platinum resistance probe 8 passes through a through hole in the flange 4 and is fixed in the probe mounting hole, allowing the platinum resistance probe 8 to be installed from the air end. Multiple semiconductor cooling chips 9 are disposed on the lower surface of the C-shaped heat-conducting plate 3.

[0023] The C-type heat-conducting plate 3 and flange 4 are welded using a vacuum furnace brazing process. The specific operation is as follows: First, the C-type heat-conducting plate 3 and flange 4 are thoroughly cleaned before welding. Then, brazing filler metal is evenly applied to the contact surfaces of the C-type heat-conducting plate 3 and flange 4 (avoiding the fixing screw holes on the contact surfaces). Next, the two are pre-fixed at the bottom of the flange using eight No. 3 1103 screws. Finally, they are placed in a vacuum brazing furnace for welding. The key to this welding process is to precisely execute the thermal cycle in a vacuum environment (at least on the order of E-3 Pa). After preheating and degassing, the temperature is rapidly heated to slightly above the liquidus line of the brazing filler metal and held at that temperature for a short time (usually 5-15 minutes). Finally, the cooling rate is controlled to reduce thermal stress, ultimately obtaining a dense and reliable weld surface with a controllable compound layer thickness.

[0024] Before being placed in the welding furnace, eight No. 3 1103 screws are used to penetrate from the bottom of the flange upwards and embed into the C-shaped heat-conducting plate 3, which further strengthens the fixed connection between the C-shaped heat-conducting plate 3 and the flange 4 and improves the reliability of the overall structure.

[0025] Furthermore, such as Figure 4 As shown, the platinum resistance probe 8 includes a platinum resistance thermometer and an oxygen-free copper screw. The platinum resistance thermometer is cryogenically soldered to the end face of the oxygen-free copper screw via an indium layer. The oxygen-free copper screw is threaded into the probe mounting hole. The platinum resistance probe 8 is a four-wire high-precision platinum resistance thermometer. Two wires are connected to each of the positive and negative leads to form a four-wire measurement system, enabling real-time and accurate measurement of the temperature inside a shielded vacuum chamber, thereby achieving precise temperature control within the chamber. Before use, the platinum resistance thermometer 8 must be precisely calibrated to reduce the calibration uncertainty to below 5 mK.

[0026] Furthermore, the probe mounting hole is a blind hole with internal threads, and a thin thermally conductive wall is formed between the bottom of the probe mounting hole and the upper surface of the C-shaped heat-conducting plate 3. This ensures that the temperature measurement point of the installed platinum resistance probe 8 is very close to the contact surface between the C-shaped heat-conducting plate 3 and the annular cavity 1, thus ensuring that the temperature measured by the platinum resistance probe 8 accurately reflects the true temperature inside the annular cavity 1. The flange 4 is used to install the vacuum chamber. The C-shaped heat-conducting plate 3 is used for both temperature control and measurement of the annular cavity 1 (temperature control is achieved through the semiconductor cooling chip 9, and temperature measurement is achieved through the platinum resistance probe 8), and also serves as a vacuum isolation function (the part of the annular cavity 1 that is not in contact with the C-shaped heat-conducting plate 3 is in a vacuum environment).

[0027] In some embodiments, the annular cavity 1, cavity bottom plate, cavity cover 2, C-shaped heat-conducting plate 3, atomic beam inlet channel 501, and atomic beam outlet channel 502 are all made of oxygen-free copper. The inner surface of the annular cavity 1, the inner surface of the cavity bottom plate, the inner surface of the cavity cover 2, the inner surface of the atomic beam inlet channel 501, the inner surface of the atomic beam outlet channel 502, and the two side plates and edge surfaces of the C-shaped heat-conducting plate 3 are all covered with a conductive coating with low outgassing rate and high thermal radiation coefficient. The conductive coating is made by thoroughly mixing multi-walled carbon nanotube powder with a purity greater than 99.9% with organosilicon resin at a mass ratio of 1:2. The thermal radiation coefficient of the conductive coating is 0.95. All the materials constituting the conductive coating are low outgassing materials, so it is suitable for ultra-high vacuum environments on the E-9Pa level. Before installation, the polyhedral cavity 1, cavity cover 2, atomic beam inlet channel 501, atomic beam outlet channel 502, and window pressure ring 7 need to be ultrasonically cleaned in anhydrous ethanol with a purity greater than 99.5% for about 10 minutes, and then removed and dried before assembly.

[0028] Furthermore, the C-shaped heat-conducting plate 3 has a radially spaced slit with a width of 10mm. The window retaining ring 7 has a 0.5mm wide slit. The cavity cover 2, the annular cavity 1, and the cavity base plate all have slits of the same width (0.3mm) in the same radial direction. After installation, the slits in the same radial direction on the cavity cover 2, the cavity cover 2, the annular cavity 1, and the cavity base plate are aligned radially with the slits in the C-shaped heat-conducting plate 3, thus preventing eddy currents from forming within the blackbody radiation shielding cavity due to changes in the ambient magnetic field.

[0029] Furthermore, the first to twelfth flat window panes 612 are made of borosilicate crown glass (BK7 glass) with a thickness of 6mm and an effective light-transmitting aperture of 16mm. BK7 material can block the transmission of far-infrared radiation with wavelengths greater than 2.8μm. The inner surfaces of the first to twelfth flat window panes 612 are coated with an indium tin oxide (ITO) antireflective film to isolate the penetration of environmental thermal radiation and prevent DC Stark frequency shift caused by accumulated charges on the inner surface of the window panes. The flange 4 is made of titanium alloy, which has high strength, good corrosion resistance, and is lightweight. Through the above treatment, the inner wall of the blackbody radiation shielding cavity is constructed with a conductive thermal radiation shielding layer, making the blackbody radiation shielding cavity a nearly closed Faraday cage structure. The atomic cluster at the center of the cavity is in a near-ideal blackbody radiation thermal radiation environment, improving the measurement accuracy of the radiation field temperature and simultaneously achieving effective shielding against the environmental electric field.

[0030] In some embodiments, a blackbody radiation shielding device suitable for ultra-high vacuum environments further includes a water-cooled MOT coil 10. The thermoelectric cooler 9 and the water-cooled MOT coil 10 are disposed below the flange 4. In this embodiment, four thermoelectric coolers 9 are used, positioned on the upper surface of the water-cooled MOT coil 10 and fixed with thermally conductive epoxy resin. The thermoelectric coolers 9 are uniformly and symmetrically distributed around the central axis of the annular cavity 1. This uniform and symmetrical arrangement of the thermoelectric coolers 9 around the central axis of the annular cavity 1 effectively reduces interference from the magnetic field generated after energization. The water-cooled MOT coil 10 is fixedly connected to the flange 4 by fixing screws (not shown in the figures). After assembly, the upper surface of the thermoelectric cooler 9 is in close contact with the lower surface of the flange 4, and the lower surface of the thermoelectric cooler 9 is in close contact with the upper surface of the water-cooled MOT coil 10. The skeleton of the water-cooled MOT coil 10 is made of titanium alloy, with enameled copper wire wound around it to form a magneto-optical trap (MOT) coil. The water-cooled MOT coil 10 frame is provided with a water-cooling inlet 1001 and a water-cooling outlet 1002.

[0031] Furthermore, the four thermoelectric coolers 9 are connected in a manner that "two thermoelectric coolers 9 are connected in series to form a cooling unit, and the two cooling units are connected in parallel" to form a cooling assembly. The thermoelectric coolers 9 can reduce the required driving voltage and equivalent resistance through the above connection method, and achieve the "small voltage, large current" working mode.

[0032] In atomic clock experiments, cold atoms must be in an ultra-high vacuum environment, and the vacuum cavity must have excellent temperature uniformity to achieve a uniform thermal radiation environment. However, fluctuations in ambient temperature pose a challenge to achieving uniform cavity temperature. This invention utilizes a semiconductor cooler 9 and its heat transfer structure for temperature control of the blackbody radiation shielding cavity, fully meeting the experimental requirements. The semiconductor cooler 9 is based on the Peltier effect, is small in size, simple in structure, easy to install, and has high cooling efficiency, making it suitable as a temperature control component for the blackbody radiation shielding cavity. The heat transfer structure composed of the flange 4, C-shaped heat-conducting plate 3, and annular cavity 1 can control the temperature fluctuations within the blackbody radiation shielding cavity to within 0.01℃. In atomic clock experiments, atomic cooling, confinement, and clock probing are all completed at the center of the annular cavity 1, ensuring that the atoms are always in a temperature-controlled, isothermal thermal radiation environment. By changing the temperature control, the blackbody radiation shielding cavity can be used to analyze the influence of blackbody radiation frequency shift at different temperatures.

[0033] The water-cooled inlet 1001 and water-cooled outlet 1002 on the frame of the water-cooled MOT coil 10 are connected to the external water chiller of the present invention to remove the heat generated by the operation of the MOT coil in a timely manner.

[0034] Furthermore, screws 1101, 1102, and 1103 are all made of TC4 titanium alloy. Screw 1101 is 8mm long (M3 hexagonal head), screw 1102 is 30mm long (M4 hexagonal head), and screw 1103 is 12mm long (M4 countersunk head). Each screw has a 1.2mm through-hole from the nut to the tip, allowing residual gas to be expelled during vacuum preparation. The screw hole on the annular cavity 1 that mates with screw 1101 is a blind hole with a specific depth, preventing vacuum leakage.

[0035] This invention is applied to atomic optical clock physics systems with a vacuum level on the order of E-9 Pa. It can fully meet the experimental requirements of ultra-high vacuum environments. At room temperature, it can significantly reduce the system uncertainty of optical clocks caused by blackbody radiation frequency shift, improve the stability and reproducibility of optical clock experiments, and demonstrate important application value in the field of high-precision atomic optical frequency standards.

[0036] It should be noted that the embodiments described in this invention are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains can make various modifications or additions to the described embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A blackbody radiation shielding device suitable for ultra-high vacuum environments, comprising an annular cavity (1), characterized in that, The annular cavity (1) is circumferentially provided with one pair of atomic beam inlets and outlets and five pairs of optical windows. The bottom of the annular cavity (1) is provided with a cavity base plate, and the top of the annular cavity (1) is provided with a cavity cover (2). Optical windows are provided on the cavity cover (2) and the cavity base plate respectively. The central axis of the atomic beam inlet and outlet, the central axis of the optical windows circumferentially provided in the annular cavity (1), and the central axis of the optical windows vertically provided in the annular cavity (1) all pass through the center of the annular cavity (1). The central axis of one of the optical window pairs circumferentially provided in the annular cavity (1) is perpendicular to the central axis of the atomic beam inlet and outlet. A temperature control and measurement component is fixedly provided on the lower surface of the cavity base plate. A water-cooled MOT coil (10) is fixedly provided below the temperature control and measurement component.

2. A blackbody radiation shielding device suitable for ultra-high vacuum environments according to claim 1, characterized in that, The temperature control and measurement components include a C-type heat-conducting plate (3), a flange (4), a platinum resistance probe (8), and a semiconductor cooling chip (9). Screw No. 2 (1102) passes through the annular cavity (1) and the C-type heat-conducting plate (3) from top to bottom, securing the C-type heat-conducting plate (3) to the lower surface of the cavity base plate. Screw No. 3 (1103) passes through the flange (4) and the C-type heat-conducting plate (3) from bottom to top, pre-tightening the flange (4) to the lower surface of the C-type heat-conducting plate (3). On the surface, the C-type heat-conducting plate (3) and the flange (4) are fixed by welding. The C-type heat-conducting plate (3) is provided with a probe mounting hole. The platinum resistance probe (8) passes through the through hole provided on the flange (4) and is fixed in the probe mounting hole. The semiconductor cooling chip (9) is fixed to the upper surface of the water-cooled MOT coil (10) by thermally conductive epoxy resin. The water-cooled MOT coil (10) presses the upper surface of the semiconductor cooling chip (9) against the lower surface of the flange (4) and is fixedly connected to the flange (4).

3. A blackbody radiation shielding device suitable for ultra-high vacuum environments according to claim 2, characterized in that, There are multiple semiconductor refrigeration chips (9), two semiconductor refrigeration chips (9) are connected in series to form a refrigeration unit, and each refrigeration unit is connected in parallel. The semiconductor refrigeration chips (9) are evenly and symmetrically distributed around the central axis of the annular cavity (1).

4. A blackbody radiation shielding device suitable for ultra-high vacuum environments according to claim 2, characterized in that, The platinum resistance probe (8) includes a platinum resistance and an oxygen-free copper screw. The platinum resistance is welded to the end face of the oxygen-free copper screw through an indium layer. The oxygen-free copper screw is threadedly connected to the probe mounting hole.

5. A blackbody radiation shielding device suitable for ultra-high vacuum environments according to claim 2, characterized in that, The probe mounting hole is a blind hole, and a thermally conductive thin wall is formed between the bottom of the probe mounting hole and the upper surface of the C-shaped heat-conducting plate (3).

6. A blackbody radiation shielding device suitable for ultra-high vacuum environments according to claim 2, characterized in that, The atomic beam inlet and outlet are the atomic beam inlet channel (501) and the atomic beam outlet channel (502). The circumferentially arranged optical window pairs of the annular cavity (1) are the first flat window (601) and the sixth flat window (606), the second flat window (602) and the seventh flat window (607), the third flat window (603) and the eighth flat window (608), the fourth flat window (604) and the ninth flat window (609), and the fifth flat window (605) and the tenth flat window (610). The vertically arranged optical window pairs of the annular cavity (1) are the eleventh flat window (611) and the twelfth flat window (612). The first flat window (601) to the tenth flat window... (610) The window clips (7) are pressed onto the annular cavity (1) respectively. The window clips (7) pressing the first flat window (601) to the tenth flat window (610) are fixed onto the annular cavity (1) by screw No. 1 (1101). The eleventh flat window (611) is pressed onto the cavity bottom plate by the window clips (7). The window clips (7) pressing the eleventh flat window (611) are fixed onto the cavity bottom plate by screw No. 1 (1101). The twelfth flat window (612) is pressed onto the cavity cover (2) by the window clips (7). The window clips (7) pressing the twelfth flat window (612) are fixed onto the cavity cover (2) by screw No. 1 (1101).

7. A blackbody radiation shielding device suitable for ultra-high vacuum environments according to claim 6, characterized in that, The materials of screw No. 1 (1101), screw No. 2 (1102) and screw No. 3 (1103) are all TC4 titanium alloy. Screw through holes are opened from the nut to the tip of screw No. 1 (1101), screw No. 2 (1102) and screw No. 3 (1103). The screw hole on the annular cavity (1) that is adapted to connect with screw No. 1 (1101) is a blind hole.

8. A blackbody radiation shielding device suitable for ultra-high vacuum environments according to claim 6, characterized in that, The annular cavity (1), cavity cover (2), cavity bottom plate, C-shaped heat-conducting plate (3), window pressure ring (7) set on cavity cover (2) and window pressure ring (7) set on cavity bottom plate are all provided with gaps in the same radial direction.

9. A blackbody radiation shielding device suitable for ultra-high vacuum environments according to claim 6, characterized in that, The annular cavity (1), cavity bottom plate, cavity cover (2), C-type heat-conducting plate (3), atomic beam inlet channel (501), and atomic beam outlet channel (502) are all made of oxygen-free copper. The inner surface of the annular cavity (1), the inner surface of the cavity bottom plate, the inner surface of the cavity cover (2), the inner surface of the atomic beam inlet channel (501), the inner surface of the atomic beam outlet channel (502), and the two side plates and edge surfaces of the C-type heat-conducting plate (3) are all covered with a conductive coating with a thermal radiation coefficient of 0.

95. The inner surfaces of the first flat window (601) to the twelfth flat window (612) are coated with an ITO anti-reflection film.

10. A blackbody radiation shielding device suitable for ultra-high vacuum environments according to claim 9, characterized in that, The conductive coating is made by thoroughly mixing multi-walled carbon nanotube powder with a purity greater than 99.9% with organosilicon resin at a mass ratio of 1:2.

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