CN120491417A - Low-temperature action area device for ultralow Wen Se atomic fountain clock - Google Patents
Low-temperature action area device for ultralow Wen Se atomic fountain clockInfo
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- CN120491417A CN120491417A CN202510720367.9A CN202510720367A CN120491417A CN 120491417 A CN120491417 A CN 120491417A CN 202510720367 A CN202510720367 A CN 202510720367A CN 120491417 A CN120491417 A CN 120491417A
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Abstract
本发明涉及一种用于超低温铯原子喷泉钟的低温作用区装置，包括：液氮杜瓦瓶通过多根吊管悬挂于真空筒内，真空筒与液氮杜瓦瓶之间设置有冷屏，微波腔组件设置于液氮杜瓦瓶内；补液制冷装置位于真空筒的上方，且补液制冷装置与液氮杜瓦瓶通过液氮管道相连，用于向液氮杜瓦瓶充入液氮。本发明通过液氮杜瓦瓶的吊装结构与补液制冷装置自动补液系统结合，提高了低温作用区温度的稳定性，实现了低温环境的精准控制。液氮通过补液制冷装置自动补充，避免了手动操作引起的温度波动，同时确保微波腔谐振频率的精确调谐。再通过吊装结构结合冷屏，有效隔绝低温作用区与常温系统的热交换，避免热量损失，显著提升温度稳定性。
The present invention relates to a low-temperature action zone device for an ultra-low-temperature cesium atomic fountain clock, comprising: a liquid nitrogen dewar flask suspended in a vacuum cylinder via a plurality of hanging tubes, a cold shield disposed between the vacuum cylinder and the liquid nitrogen dewar flask, and a microwave cavity assembly disposed in the liquid nitrogen dewar flask; a liquid replenishment refrigeration device located above the vacuum cylinder, and connected to the liquid nitrogen dewar flask via a liquid nitrogen pipeline for filling the liquid nitrogen dewar flask with liquid nitrogen. The present invention improves the temperature stability of the low-temperature action zone and achieves precise control of the low-temperature environment by combining the hanging structure of the liquid nitrogen dewar flask with the automatic liquid replenishment system of the liquid replenishment refrigeration device. Liquid nitrogen is automatically replenished by the liquid replenishment refrigeration device, avoiding temperature fluctuations caused by manual operation while ensuring precise tuning of the microwave cavity resonant frequency. Furthermore, the hanging structure is combined with the cold shield to effectively isolate the heat exchange between the low-temperature action zone and the normal temperature system, avoiding heat loss and significantly improving temperature stability.
Description
Technical Field
The invention belongs to the technical field of ultralow-temperature atomic fountain clocks, and particularly relates to a low-temperature action area device for an ultralow Wen Se atomic fountain clock.
Background
The ultra-low Wen Se atomic fountain clock is used as a high-precision time-frequency reference device, has the highest accuracy performance at present, is used for calibrating other types of time-keeping atomic clocks, and the performance core of the ultra-low Wen Se atomic fountain clock depends on the stable environment of a low-temperature action area. The low-temperature action area needs to provide a low-temperature environment for the microwave cavity and the free flight area of atoms so as to inhibit the influence of the blackbody radiation frequency shift on the frequency uncertainty.
In the prior art, the low-temperature action area is generally realized by combining liquid nitrogen cooling with a vacuum heat insulation structure, for example, the temperature of the low-temperature action area is reduced and maintained by adopting a liquid nitrogen filling mode, and then a microwave cavity in the low-temperature action area is connected with a normal-temperature system below the microwave cavity in an insulating mode by utilizing a vacuum bellows, so that heat insulation is realized and the temperature difference is maintained. The contact type heat insulation design through the vacuum corrugated pipe still has the obvious defects that firstly, the liquid nitrogen temperature is not adjustable and deviates from the actual working temperature of a microwave cavity, so that the resonant frequency of the microwave cavity cannot be accurately tuned, the cavity is detuned to cause larger traction frequency shift, and finally the uncertainty of the clock frequency is increased, secondly, liquid nitrogen is usually required to be manually filled frequently during normal operation of a fountain clock, temperature fluctuation is easily caused due to the fact that liquid is manually filled, impact force in the liquid filling process causes larger temperature change, the uncertainty of blackbody radiation frequency shift is larger, thirdly, heat loss of a heat insulation structure is larger, heat transfer between a low-temperature acting area and a normal-temperature system is difficult to block, and the temperature stability is further influenced. Therefore, a need exists for a low temperature active area device for an ultra-low Wen Se atomic fountain clock.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a low-temperature action area device for an ultralow Wen Se atomic fountain clock. The technical problems to be solved by the invention are realized by the following technical scheme:
The invention provides a low-temperature acting area device for an ultralow Wen Se atomic fountain clock, which comprises a liquid nitrogen dewar, a microwave cavity assembly, a liquid supplementing refrigerating device and a liquid nitrogen dewar, wherein the liquid nitrogen dewar is suspended in a vacuum cylinder through a plurality of hanging pipes, a cold screen is arranged between the vacuum cylinder and the liquid nitrogen dewar, the microwave cavity assembly is arranged in the liquid nitrogen dewar, the liquid supplementing refrigerating device is positioned above the vacuum cylinder, and the liquid supplementing refrigerating device is connected with the liquid nitrogen dewar through a liquid nitrogen pipeline and is used for filling liquid nitrogen into the liquid nitrogen dewar.
In one embodiment of the invention, the liquid nitrogen dewar comprises a double-layer hollow cylinder, an open-pore flange and an annular copper base, wherein the double-layer hollow cylinder is provided with a hollow inner cavity, and the bottom of the double-layer hollow cylinder is connected with the annular copper base through the open-pore flange.
In one embodiment of the invention, the perforated flange is provided with a plurality of through holes, the annular copper base is provided with a groove, and the hollow inner cavity is communicated with the groove through the plurality of through holes.
In one embodiment of the invention, the cold screen is provided with two layers, a plurality of vent holes are arranged on the two layers of the cold screen, and the vent holes on the two layers of the cold screen are staggered.
In one embodiment of the invention, the two layers of cold shields are connected with the upper end of the liquid nitrogen dewar through a screw, a sleeve is arranged outside the screw, and a plurality of holes are arranged on the side wall of the sleeve.
In one embodiment of the invention, the microwave cavity assembly comprises a microwave cavity, a microwave cavity base, a T-shaped insulating ceramic tube, an annular ceramic plate, a titanium spring washer, an inner hexagonal screw and an outer hexagonal screw, wherein the microwave cavity is fixed at the upper end of the microwave cavity base through the inner hexagonal screw, the T-shaped insulating ceramic tube, the annular ceramic plate and the titanium spring washer are sleeved outside the inner hexagonal screw, the annular ceramic plate is arranged between the lower surface of the microwave cavity and the upper surface of the microwave cavity base, the titanium spring washer is arranged between the T-shaped insulating ceramic tube and the end part of the inner hexagonal screw, and the lower end of the microwave cavity base is connected with the annular copper base through the outer hexagonal screw.
In one embodiment of the invention, the liquid nitrogen pipeline passes through the vacuum cylinder and the two layers of cold shields to be communicated with the hollow inner cavity.
In one embodiment of the invention, the liquid supplementing and refrigerating device comprises a refrigerator, a temperature monitor and a low-temperature controller, wherein the refrigerator is communicated with the hollow inner cavity through the liquid nitrogen pipeline, the temperature monitor is used for monitoring the liquid nitrogen temperature, the refrigerator refrigerates liquid nitrogen according to the liquid nitrogen temperature, and the low-temperature controller heats the liquid nitrogen according to the liquid nitrogen temperature.
In one embodiment of the invention, a plurality of hanging pipes penetrate through the cold screen, the upper end of the liquid nitrogen dewar is hung on the vacuum cylinder through the hanging pipes, and the side wall of each hanging pipe is provided with a plurality of openings.
In one embodiment of the invention, the low-temperature action zone device for the ultra-low Wen Se atomic fountain clock further comprises an exhaust pipeline, wherein the exhaust pipeline penetrates through the vacuum cylinder and is communicated with the hollow inner cavity, and the exhaust pipeline is connected with an exhaust valve.
Compared with the prior art, the invention has the beneficial effects that:
The low-temperature action area device for the ultralow Wen Se atomic fountain clock is combined with the automatic liquid supplementing system of the liquid supplementing refrigeration device through the hoisting structure of the liquid nitrogen dewar, so that the stability of the temperature of the low-temperature action area is improved, and the accurate control of the low-temperature environment is realized. The liquid nitrogen is automatically supplemented by the liquid supplementing refrigeration device, so that temperature fluctuation caused by manual operation is avoided, and meanwhile, accurate tuning of the resonant frequency of the microwave cavity is ensured. And the cold screen is combined through the hoisting structure, so that heat exchange between the low-temperature action area and the normal-temperature system is effectively isolated, heat loss is avoided, and the temperature stability is remarkably improved.
The invention fills the annular copper base with liquid nitrogen by using the perforated flange, so that the temperature of the microwave cavity is kept consistent with that of the liquid nitrogen, the insulation and heat conduction of the microwave cavity are realized by adopting the annular ceramic plate, and the vacuum pumping and heat radiation shielding are taken into consideration by the staggered arrangement of the vent holes of the double-layer cold screen and the sleeve supporting structure, so that a reliable running environment with low noise and high stability is provided for the ultra-low temperature atomic fountain clock.
The foregoing description is only an overview of the present invention, and is intended to be implemented in accordance with the teachings of the present invention, as well as the preferred embodiments thereof, together with the following detailed description of the invention given in conjunction with the accompanying drawings.
Drawings
FIG. 1 is a schematic diagram of a low temperature region of action device for an ultra-low Wen Se atomic fountain clock according to an embodiment of the present invention;
FIG. 2 is a schematic view of a partial structure of a liquid nitrogen dewar provided by an embodiment of the present invention;
FIG. 3 is a schematic diagram of a connection structure of a microwave cavity assembly according to an embodiment of the present invention;
fig. 4 is a schematic view of a hoisting structure according to an embodiment of the present invention.
The reference numerals comprise a 100-vacuum cylinder, a 200-liquid nitrogen Dewar, a 201-double-layer hollow cylinder, a 202-perforated flange, a 203-annular copper base, a 300-cold screen, a 301-sleeve, a 302-screw, a 303-nut, a 400-microwave cavity assembly, a 401-microwave cavity, a 402-T-shaped insulating ceramic tube, a 403-annular ceramic sheet, a 404-titanium spring washer, a 405-microwave cavity base, a 406-inner hexagon screw, a 407-outer hexagon screw, a 500-liquid supplementing refrigerating device, a 501-refrigerator, a 502-temperature monitor, a 503-low temperature controller, a 600-liquid nitrogen pipeline, a 700-hanging tube, a 800-exhaust pipeline and a 900-exhaust valve.
Detailed Description
In order to further describe the technical means and effects adopted by the invention to achieve the preset aim, the following describes in detail a low-temperature action area device for an ultra-low Wen Se atomic fountain clock according to the invention with reference to the attached drawings and the detailed description.
The foregoing and other features, aspects, and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments when taken in conjunction with the accompanying drawings. The technical means and effects adopted by the present invention to achieve the intended purpose can be more deeply and specifically understood through the description of the specific embodiments, however, the attached drawings are provided for reference and description only, and are not intended to limit the technical scheme of the present invention.
Example 1
The existing low-temperature action area is generally realized by combining liquid nitrogen cooling with a vacuum heat insulation structure, but the problems of inaccurate temperature control, low liquid supplementing efficiency, uneven heat conduction between a microwave cavity and liquid nitrogen and insufficient heat stability of the low-temperature action area still exist. As shown in fig. 1 to 4, fig. 1 is a schematic structural diagram of a low-temperature action area device for an ultra-low Wen Se atomic fountain clock according to an embodiment of the present invention, fig. 2 is a schematic partial structural diagram of a liquid nitrogen dewar provided by an embodiment of the present invention, fig. 3 is a schematic connecting structure of a microwave cavity assembly provided by an embodiment of the present invention, and fig. 4 is a schematic lifting structure provided by an embodiment of the present invention.
In the embodiment, the low-temperature action area device for the ultra-low Wen Se atomic fountain clock comprises a vacuum cylinder 100, a liquid nitrogen dewar 200, a cold screen 300, a microwave cavity assembly 400 and a liquid supplementing refrigeration device 500, wherein the liquid nitrogen dewar 200 is suspended in the vacuum cylinder 100 through a plurality of hanging pipes 700, the cold screen 300 is arranged between the vacuum cylinder 100 and the liquid nitrogen dewar 200, the microwave cavity assembly 400 is arranged in the liquid nitrogen dewar 200, the liquid supplementing refrigeration device 500 is positioned above the vacuum cylinder 100, and the liquid supplementing refrigeration device 500 is connected with the liquid nitrogen dewar 200 through a liquid nitrogen pipeline 600 and is used for filling liquid nitrogen into the liquid nitrogen dewar 200.
The principle is that vacuum is pumped in the vacuum cylinder 100, and the microwave cavity assembly 400 is arranged in a low-temperature action area because the microwave cavity assembly 400 depends on low temperature to maintain stability, namely, the low-temperature action area is formed in the internal environment of the vacuum cylinder 100 through liquid nitrogen cooling. To avoid temperature loss, the low temperature region of action is physically isolated from its surroundings, including reducing heat radiation outside the vacuum drum 100 by cold screen 300, and suspending the liquid nitrogen dewar 200 within the vacuum drum 100 by a plurality of suspension tubes 700. In addition, in order to avoid temperature fluctuation caused by impact in the liquid supplementing process, automatic liquid supplementing is also realized through the liquid supplementing refrigeration device 500, so as to improve the stability of the low-temperature acting region.
In an alternative embodiment, liquid nitrogen dewar 200 comprises a double-layered hollow cylinder 201, an apertured flange 202 and an annular copper base 203, double-layered hollow cylinder 201 is provided with a hollow interior cavity, and the bottom of double-layered hollow cylinder 201 is connected to annular copper base 203 by apertured flange 202.
In an alternative embodiment, the open-pore flange 202 and the bottom of the double-layer hollow cylinder 201 are sealed by welding, the open-pore flange 202 is provided with a plurality of through holes, the annular copper base 203 is provided with a groove, the open-pore flange 202 wraps the annular copper base 203, the hollow inner cavity of the double-layer hollow cylinder 201 is communicated with the groove through the plurality of through holes, liquid nitrogen flows downwards after being filled into the hollow inner cavity through the liquid nitrogen pipeline 600, and flows into the groove of the annular copper base 203 through the plurality of through holes, so that the contact area between the double-layer hollow cylinder 201 and the annular copper base 203 is increased, the stability of the Dewar structure is ensured, and direct heat conduction to the microwave cavity 401 is facilitated. The interior of the liquid nitrogen dewar 200 is filled with liquid nitrogen during normal operation to provide a low temperature environment for the interior microwave cavity 401 and the upper atomic free flight zone.
For example, the double-layered hollow cylinder 201 may be made of a titanium alloy material.
Illustratively, the groove of the annular copper base 203 is annular, and the plurality of through holes are also arranged along the circumference, so that the contact area of the annular copper base 203 is increased through the annular groove structure, and the uniform transfer of the liquid nitrogen cooling capacity to the microwave cavity 401 is ensured.
Illustratively, the upper end of the double-layer hollow cylinder 201 is provided with a double-layer end cover structure, and the center through hole of the double-layer end cover is used for microwave cable routing, and the two holes are sealed by welding a titanium alloy pipeline.
In an alternative embodiment, the cold screen 300 is provided with two layers, a plurality of ventilation holes are formed in the two layers of cold screen 300, and the ventilation holes in the two layers of cold screen 300 are staggered, so as to ensure vacuum pumping, and simultaneously effectively reduce direct heat radiation of the external environment of the vacuum cylinder 100 to the low-temperature action area. Further, in order to realize the connection and fixation between the cold shield 300 and the liquid nitrogen dewar 200, the two layers of cold shields 300 are connected with the upper end of the liquid nitrogen dewar 200 through a screw 302. Specifically, two screws 302 are welded at the upper end of the liquid nitrogen dewar 200, openings are arranged at corresponding positions of the two layers of cold shields 300, and the two screws 302 pass through the openings and are fixedly installed by using nuts 303. The casing 301 is arranged outside the screw 302, a plurality of holes are arranged on the side wall of the casing 301, and the casing 301 is used for supporting the cold screen 300 and adjusting the distance and plays a role in maintaining the temperature difference between the two layers of cold screens 300.
Illustratively, both cold shields 300 may be made of pure copper, and silver plating is performed on the surfaces of both cold shields 300 to avoid copper oxidation and reduce heat radiation.
Further, the nesting of two-layer cold screen 300 sets up, and the internal diameter of two-layer cold screen 300 is 238mm, 268mm respectively, and the height is 645mm, 693mm respectively, and the thickness of two-layer cold screen 300 is 2mm, and equidistant evenly setting of air vent on the two-layer cold screen 300, if the air vent sets up to 4 rows and 4 columns, the aperture of every air vent is 20mm, and the air vent of two-layer cold screen 300 staggers the setting when the installation.
In this embodiment, the microwave cavity assembly 400 includes a microwave cavity 401, a microwave cavity base 405, a T-shaped insulating ceramic tube 402, an annular ceramic plate 403, a titanium spring washer 404, an inner hexagonal screw 406 and an outer hexagonal screw 407, wherein the lower end of the microwave cavity 401 is fixedly connected to the upper end of the microwave cavity base 405 by the inner hexagonal screw 406, the inner hexagonal screw 406 is sleeved with the T-shaped insulating ceramic tube 402, the annular ceramic plate 403 and the titanium spring washer 404, the annular ceramic plate 403 is disposed between the lower surface of the microwave cavity 401 and the upper surface of the microwave cavity base 405, the titanium spring washer 404 is disposed between the T-shaped insulating ceramic tube 402 and the end of the inner hexagonal screw 406, and the lower end of the microwave cavity base 405 is connected to the annular copper base 203 by the outer hexagonal screw 407.
By way of example, the annular ceramic plate 403 may be made of aluminum nitride material, and the socket head cap screws 406 penetrate the annular ceramic plate 403, and the annular ceramic plate 403 is used for insulation of the microwave cavity 401 and is capable of rapidly conducting the liquid nitrogen temperature to the microwave cavity 401. Further, the microwave cavity 401 may be made of pure copper, when the temperature in the low temperature acting area changes, copper is obviously affected by temperature, and expansion and contraction will occur, so as to prevent the annular ceramic plate 403 between the microwave cavity 401 and the heated and crushed ceramic plate, and a titanium spring washer 404 is installed on an inner hexagon screw 406 for fixing the microwave cavity 401 to reserve a deformation space.
Further, the lower end of the microwave cavity 401 is connected with the upper end of the microwave cavity base 405 through 8 socket head cap screws 406 uniformly arranged along the circumference, a T-shaped insulating ceramic tube 402 is sleeved outside each socket head cap screw 406 for insulation, and each socket head cap screw 406 is provided with a titanium spring washer 404. Similarly, the lower end of the microwave cavity mount 405 is connected to the annular copper mount 203 by 12 circumferentially uniformly disposed outer hex screws 407.
In this embodiment, the liquid-supplementing refrigeration device 500 comprises a refrigerator 501, a temperature monitor 502 and a low-temperature controller 503, wherein a liquid nitrogen pipeline 600 passes through the vacuum cylinder 100 and the two-layer cold screen 300 to be communicated with the hollow inner cavity, the refrigerator 501 is communicated with the hollow inner cavity through the liquid nitrogen pipeline 600, the temperature monitor 502 is used for monitoring the temperature of liquid nitrogen, the refrigerator 501 refrigerates the liquid nitrogen according to the temperature of the liquid nitrogen, and the low-temperature controller 503 heats the liquid nitrogen according to the temperature of the liquid nitrogen.
The temperature control of the low temperature acting area is realized by a temperature monitor 502 and a low temperature controller 503, the temperature monitor 502 is respectively in communication connection with the refrigerator 501 and the low temperature controller 503, meanwhile, the refrigerator 501, the temperature monitor 502 and the low temperature controller 503 are all connected with an external control module, the temperature monitor 502 can adopt a Lake Shore 218 type temperature monitor, the low temperature controller 503 can adopt a Lake Shore 336 type low temperature controller, and the temperature control of the liquid nitrogen temperature in the range of 77 k-87 k can be realized by combining with the refrigerator 501 through the control of the external control module.
Further, the low-temperature controller 503 is disposed below the driving piston of the refrigerator 501, the low-temperature controller 503 is provided with an independent heater, the refrigerator 501 and the low-temperature controller 503 are both controlled by an external control module through PID (proportional-integral-derivative control) to perform closed-loop temperature control according to the liquid nitrogen temperature, so as to realize the adjustment of the liquid nitrogen temperature. The operation of the liquid replenishing refrigeration device 500 is as follows, and the liquid replenishing refrigeration device is communicated with the hollow cavity of the liquid nitrogen dewar 200 through a liquid nitrogen pipeline 600. The temperature monitor 502 monitors the temperature of the liquid nitrogen within the liquid nitrogen dewar 200 in real time and transmits temperature signals to the refrigerator 501 and the cryogenic controller 503. When the liquid nitrogen temperature is higher than the set value, the refrigerator 501 is started, the refrigeration of the liquid nitrogen is realized through the refrigerant circulation in the refrigerator 501, the liquid nitrogen temperature is reduced, and when the liquid nitrogen temperature is lower than the set value, the low-temperature controller 503 is started, and the heating element is used for heating the liquid nitrogen, so that the liquid nitrogen temperature is increased. The refrigerator 501 and the low-temperature controller 503 work simultaneously or in a time-sharing mode under the coordination of an external control module, closed-loop temperature control is carried out according to a PID algorithm, and the temperature of liquid nitrogen is accurately regulated within the range of 77K-87K.
In an alternative implementation manner, the low-temperature action area device for the ultra-low Wen Se atomic fountain clock of the embodiment further comprises an exhaust pipeline 800, the exhaust pipeline 800 passes through the vacuum cylinder 100 to be communicated with the hollow inner cavity, and the exhaust pipeline 800 is connected with an exhaust valve 900.
The principle of the device is that a liquid nitrogen pipeline 600 is used as a pipeline for inputting and outputting liquid nitrogen, a refrigerator 501 is a GM (Gifford-McMahon) refrigerator and is connected with a condenser, and the processes of liquid nitrogen evaporation, cooling, liquefaction and reflux are utilized to realize the stability of the temperature of an ultralow temperature action area and the zero evaporation cycle use of the liquid nitrogen and realize automatic condensation quasi-static liquid filling. Specifically, two installation fixing holes are symmetrically formed at the upper end of the outer layer of the liquid nitrogen dewar 200 with respect to the center, one installation fixing hole is connected with the refrigerator 501 through a liquid nitrogen pipeline 600 to inject liquid nitrogen, after the liquid nitrogen in the liquid nitrogen dewar 200 is gasified, low-temperature nitrogen returns to the refrigerator 501 along the liquid nitrogen pipeline 600, and is cooled again to be low-temperature liquid nitrogen after being cooled by the refrigerator 501 for circulation, and enters the hollow inner cavity of the liquid nitrogen dewar 200 through the liquid nitrogen pipeline 600 under the action of gravity again, so that the temperature stability of a low-temperature action area is maintained, the function of automatically condensing quasi-static liquid filling is realized, and zero evaporation of the liquid nitrogen is recycled. The other mounting fixing hole of the liquid nitrogen dewar 200 is connected to the degassing valve 900 through the degassing pipe 800 for discharging gas during the initial mounting process, that is, discharging internal gas during the initial filling of liquid nitrogen, ensuring the flow stability of liquid nitrogen.
In an alternative embodiment, the cold screen 300 is further provided with a lifting hole, the plurality of lifting pipes 700 penetrate through the lifting hole on the cold screen 300, the side wall of the lifting pipe 700 is provided with a plurality of openings, direct heat radiation of the external environment of the vacuum cylinder 100 to a low-temperature action area is effectively reduced, vacuum pumping is not affected, and the upper end of the liquid nitrogen dewar 200 is suspended on the vacuum cylinder 100 through the plurality of lifting pipes 700. Specifically, taking four holes in total of two lifting holes and two mounting fixing holes, and two lifting pipes 700 as an example, the two lifting pipes 700 and the other liquid nitrogen pipeline 600 and the exhaust pipeline 800 are all arranged along the vertical direction, and the two lifting holes and the two mounting fixing holes are arranged in a rectangular shape, wherein the two lifting holes are arranged diagonally, the two mounting fixing holes are arranged diagonally, and the whole low-temperature action area is lifted through the liquid nitrogen pipeline 600, the lifting pipes 700 and the exhaust pipeline 800, so that heat loss caused by direct contact of the low-temperature action area and a normal-temperature physical system below is avoided.
The side wall of the hanging pipe 700 is provided with a plurality of holes to avoid influencing vacuum pumping, the two hanging pipes 700, the liquid nitrogen pipeline 600 and the exhaust pipeline 800 are welded at the upper end of the outer layer of the liquid nitrogen dewar 200 and are also welded with the vacuum cylinder 100, and the corresponding positions of the upper end of the cold screen 300 are also provided with lifting holes to ensure that the two hanging pipes 700, the liquid nitrogen pipeline 600 and the exhaust pipeline 800 do not contact with the cold screen 300 to pass through, thereby realizing both lifting and heat insulation.
It is worth noting that the low-temperature action area device for the ultra-low Wen Se atomic fountain clock realizes the adjustability of the temperature of the low-temperature action area within the range of 10K, improves the temperature stability and reduces the uncertainty of the frequency shift of the blackbody radiation. Insulation of the microwave cavity 401 and direct contact of the microwave cavity 401 and liquid nitrogen are achieved, traction frequency shift of the microwave cavity 401 is effectively reduced, frequency uncertainty of the fountain clock is improved, and high performance of the atomic clock is achieved. Specifically, the invention adopts an automatic condensing quasi-static liquid nitrogen supplementing mode to reduce and maintain the temperature of a low-temperature action area, utilizes the perforated flange 202 to fill the annular copper base 203 with liquid nitrogen, keeps the temperature of the microwave cavity 401 consistent with that of the liquid nitrogen, adopts a mode of combining an aluminum nitride ceramic plate and a spring washer to realize the insulation and heat conduction of the microwave cavity 401, and is insulated with a lower normal-temperature system by hoisting the low-temperature action area. The temperature control system based on the liquid supplementing refrigeration device 500 enables the temperature of the low-temperature acting area to be adjustable within 77K-87K, and the microwave cavity 401 can be further tuned conveniently. Compared with the traditional structural design, the heat loss and the impact force generated in the manual fluid infusion process are avoided, and the stability of the temperature of the low-temperature action area is improved. The liquid nitrogen filling device has the characteristics of no magnetism, good heat conduction between the microwave cavity 401 and liquid nitrogen, controllable temperature, further tuning of the microwave cavity 401 in a low-temperature action area and automatic quasi-static liquid filling.
The low-temperature action area device for the ultralow Wen Se atomic fountain clock is combined with the automatic liquid supplementing system of the liquid supplementing refrigeration device through the hoisting structure of the liquid nitrogen dewar, so that the stability of the temperature of the low-temperature action area is improved, and the accurate control of the low-temperature environment is realized. The liquid nitrogen is automatically supplemented by the liquid supplementing refrigeration device, so that temperature fluctuation caused by manual operation is avoided, and meanwhile, accurate tuning of the resonant frequency of the microwave cavity is ensured. And the cold screen is combined through the hoisting structure, so that heat exchange between the low-temperature action area and the normal-temperature system is effectively isolated, heat loss is avoided, and the temperature stability is remarkably improved.
The invention fills the annular copper base with liquid nitrogen by using the perforated flange, so that the temperature of the microwave cavity is kept consistent with that of the liquid nitrogen, the insulation and heat conduction of the microwave cavity are realized by adopting the annular ceramic plate, and the vacuum pumping and heat radiation shielding are taken into consideration by the staggered arrangement of the vent holes of the double-layer cold screen and the sleeve supporting structure, so that a reliable running environment with low noise and high stability is provided for the ultra-low temperature atomic fountain clock.
It should be noted that in this document relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that an article or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed. Without further limitation, an element defined by the phrase "comprising one does not exclude the presence of other like elements in an article or apparatus that comprises the element. The terms "connected" or "connected," and the like, are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The orientation or positional relationship indicated by "upper", "lower", "left", "right", etc. is based on the orientation or positional relationship shown in the drawings, and is merely for convenience of description and to simplify the description, and is not indicative or implying that the apparatus or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention.
The foregoing is a further detailed description of the invention in connection with the preferred embodiments, and it is not intended that the invention be limited to the specific embodiments described. It will be apparent to those skilled in the art that several simple deductions or substitutions may be made without departing from the spirit of the invention, and these should be considered to be within the scope of the invention.
Claims (10)
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