Microwave cavity for a cold atom microwave clock

Abstract

The present application relates to a kind of microwave cavities for cold atom microwave clock, belong to cold atom clock field, comprising: main cavity, rectangular waveguide, upper end cover, lower end cover and frequency tuning component;The end cover of main cavity is fixed and sealed with main cavity, the end cover of rectangular waveguide is fixed and sealed with rectangular waveguide itself using laser welding, fundamentally avoid the unreliability problem caused by indium wire sealing, no need to carry out aging test again, shorten the development time of microwave cavity again.The frequency tuning of main cavity is realized using tuning component, the frequency tuning of rectangular waveguide is realized using tuning screw, through double tuning mode and laser welding synergistic effect, no longer need to repeatedly disassemble and grind debugging, further shorten the development time of microwave cavity, simplify assembly and tuning process, be conducive to realization standardization, realize industrialization development.The present application solves the tuning problem of the frequency of cold atom clock microwave cavity, also effectively solves the low reliability, tuning process complex problem caused by using indium wire sealing.

Description

Technical Field

[0001] This invention belongs to the field of cold atom clocks, and specifically relates to a microwave cavity for a cold atom microwave clock. Background Technology

[0002] Atomic clocks are the first high-precision timing devices based on the principles of quantum mechanics. Cold atom clocks use cold atoms with temperatures on the order of μK as frequency discriminants. Their accuracy surpasses that of traditional hot atom clocks by 1 to 2 orders of magnitude. They are currently the most accurate time and frequency timing and measurement devices and are widely used in metrology, satellite navigation, national defense, and communications.

[0003] Cold atom microwave clocks utilize the interaction between cold atoms and microwaves to lock the frequency of an external microwave oscillator onto the atomic energy level, thereby outputting a time and frequency signal with cold atom stability. The microwave cavity is the core component of a cold atom microwave clock, serving as the site for the interaction between cold atoms and external microwaves. The microwave cavity typically uses a cylindrical cavity as its main body, with rectangular waveguides on the sidewalls. External microwaves enter the main cavity through a two-stage coupling process.

[0004] In the development of microwave cavities, the resonant frequency tuning of the main cavity and rectangular waveguide is typically achieved through grinding. The process is as follows: After machining the structure, the surfaces of the main cavity and the rectangular waveguide end caps are ground with sandpaper. This process involves repeated grinding and adjustment, requiring constant disassembly and reassembly of the end caps and the main cavity, as well as the rectangular waveguide end caps and the rectangular waveguide, until the cavity resonant frequency requirement is met. Finally, the end caps of the main cavity and the rectangular waveguide are fixed with non-magnetic screws. The microwave cavity also requires indium wire sealing of the end caps to suppress microwave leakage. Since the microwave cavity operates in a high-vacuum environment, and achieving this high vacuum requires high-temperature baking, microwave cavities sealed with indium wires need to undergo high and low temperature aging tests. After the aging tests, at least one month of static observation is required to confirm that the resonant frequency of the cavity no longer changes. Because the tuning and sealing processes of the microwave cavity can interact, ensuring reliability not only complicates the structure and tuning process but also further prolongs the development time, significantly hindering the standardization and industrialization of cold atom microwave clocks. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, this invention provides a microwave cavity for a cold atom microwave clock. The technical problem to be solved by this invention is achieved through the following technical solution:

[0006] This invention provides a microwave cavity for a cold atom microwave clock, comprising: a main cavity body with two rectangular waveguides symmetrically arranged on its sidewalls and sealed by welding; an upper end cover welded to the upper end of the main cavity body, the center of which has an extending upper cylindrical cutoff waveguide; a lower end cover welded to the lower end of the main cavity body, the center of which has an extending lower cylindrical cutoff waveguide; a frequency tuning assembly including an upper tuning cover and a lower tuning cover, the upper tuning cover pressing on the upper end cover and the lower tuning cover pressing on the lower end cover, and the upper and lower tuning covers being connected by multiple tuning screws; a threaded hole at the center of each rectangular waveguide, and a tuning screw connected to the threaded hole; wherein, each tuning screw has a locking nut connected to both ends, and by tightening the locking nut, the upper and lower end covers are deformed to change the resonant frequency of the main cavity body; the resonant frequency of the rectangular waveguide is tuned by adjusting the screw depth of the tuning screw.

[0007] In one embodiment of the present invention, the sidewall of the main cavity is symmetrically provided with small holes, and the two rectangular waveguides are respectively coupled to the main cavity through the small holes.

[0008] In one embodiment of the present invention, the microwave cavity for a cold atom microwave clock further includes a semi-rigid cable, which is coupled to the rectangular waveguide via an inner conductor probe.

[0009] In one embodiment of the present invention, the upper cylindrical cutoff waveguide and the lower cylindrical cutoff waveguide are coaxially arranged and serve as a cold atom channel.

[0010] In one embodiment of the present invention, the upper cylindrical cutoff waveguide is covered with a copper tube, and the copper tube outside the upper cylindrical cutoff waveguide at least covers the free flight region of atoms; the lower cylindrical cutoff waveguide is covered with a copper tube, and the lower cylindrical cutoff waveguide extends to the detection region of the cold atom microwave clock.

[0011] In one embodiment of the present invention, the lower cylindrical cutoff waveguide has a positioning disk in the middle and a fixing disk at the end, and the fixing disk has a plurality of connection holes.

[0012] In one embodiment of the present invention, the upper tuning cover is a square plate with a through hole in the middle; the lower tuning cover is a square plate with a U-shaped groove; the four corners of the upper and lower tuning covers are provided with threaded holes to connect the tuning screw.

[0013] In one embodiment of the invention, the tuning screw is threaded to the rectangular waveguide and sealed by non-magnetic solder after tuning.

[0014] In one embodiment of the present invention, the main cavity, the rectangular waveguide, the upper end cover, and the lower end cover are all made of oxygen-free copper material.

[0015] In one embodiment of the present invention, the upper tuning cover, the lower tuning cover, the tuning screw, and the locking nut are all made of titanium.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] The microwave cavity for a cold atom microwave clock of the present invention has a main cavity body and a rectangular waveguide sealed by welding. At the same time, the upper end cover and the lower end cover are also welded to the main cavity body. The welding seal replaces the traditional indium wire seal, thus eliminating the need to design high and low temperature aging tests and avoiding the risk of aging and deformation of indium wire seals. It effectively prevents microwave leakage, simplifies the structure, improves sealing reliability, and shortens the development time of microwave cavity.

[0018] The microwave cavity of the cold atom microwave clock of the present invention is equipped with a frequency tuning component. Even if the resonant frequency of the main cavity changes after welding, the upper and lower end covers can be deformed by tightening the locking nut, thereby changing the resonant frequency of the main cavity and achieving quick adjustment. Therefore, there is no need to use traditional indium wire sealing and corresponding aging test.

[0019] The microwave cavity for a cold atom microwave clock of the present invention integrates a rectangular waveguide and its end cap as one unit. The rectangular waveguide is then sealed to the main cavity body by welding. The resonant frequency of the rectangular waveguide is tuned by adjusting the insertion depth of the tuning screw. This alters the tuning method of the rectangular waveguide's resonant frequency and simplifies its structure. After tuning, the outer surface of the rectangular waveguide in contact with the tuning screw is soldered with non-magnetic solder, thus completely eliminating the possibility of microwave leakage from the tuning screw.

[0020] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0021] Figure 1 This is a structural diagram of a microwave cavity for a cold atom microwave clock provided in an embodiment of the present invention;

[0022] Figure 2 This is provided by the embodiments of the present invention. Figure 1 Schematic diagram of the structure at point I;

[0023] Figure 3 This is a schematic diagram of the main cavity structure provided in an embodiment of the present invention;

[0024] Figure 4 This is a structural cross-sectional view of the microwave cavity for a cold atom microwave clock provided in an embodiment of the present invention;

[0025] Figure 5 This is provided by the embodiments of the present invention. Figure 4 Schematic diagram of the structure at point II;

[0026] Figure 6 This is a schematic diagram of the structure of the frequency tuning component provided in an embodiment of the present invention.

[0027] Reference numerals: 1-Main cavity; 11-Small hole; 2-Rectangular waveguide; 21-Tuning screw; 3-Semi-rigid cable; 4-Upper end cover; 41-Upper cylindrical cutoff waveguide; 5-Lower end cover; 51-Lower cylindrical cutoff waveguide; 511-Positioning plate; 512-Fixing plate; 6-Frequency tuning assembly; 61-Upper tuning cover; 62-Lower tuning cover; 63-Tuning screw. Detailed Implementation

[0028] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the following detailed description of a microwave cavity for a cold atom microwave clock, in conjunction with the accompanying drawings and specific embodiments, is provided.

[0029] The foregoing and other technical contents, features, and effects of the present invention will be clearly presented in the following detailed description of specific embodiments in conjunction with the accompanying drawings. Through the description of the specific embodiments, a more in-depth and concrete understanding can be gained of the technical means and effects adopted by the present invention to achieve its intended purpose. However, the accompanying drawings are for reference and illustration only and are not intended to limit the technical solutions of the present invention.

[0030] Example 1

[0031] Existing microwave cavities suffer from low reliability, complex debugging and sealing processes, and long processing times, which hinder the standardization and industrialization of cold atom microwave clocks. Therefore, this invention provides a microwave cavity for cold atom microwave clocks, such as... Figure 1 and Figure 2 As shown, Figure 1 This is a structural diagram of a microwave cavity for a cold atom microwave clock provided in an embodiment of the present invention; Figure 2 This is provided by the embodiments of the present invention. Figure 1 A schematic diagram of the structure at point I.

[0032] In this embodiment, the microwave cavity for a cold atom microwave clock includes: a main cavity 1, a rectangular waveguide 2, an upper end cover 4, a lower end cover 5, and a frequency tuning assembly 6. Two rectangular waveguides 2 are symmetrically arranged on the sidewalls of the main cavity 1 and sealed by welding. The upper end cover 4 is welded to the upper end of the main cavity 1, and an extended upper cylindrical cutoff waveguide 41 is located at the center of the upper end cover 4. The lower end cover 5 is welded to the lower end of the main cavity 1, and an extended lower cylindrical cutoff waveguide 51 is located at the center of the lower end cover 5. The frequency tuning assembly 6 includes an upper tuning cover 61 and a lower tuning cover 62. The upper tuning cover 61 presses onto the upper end cover 4, and the lower tuning cover 62 presses onto the lower end cover 5. The upper tuning cover 61 and the lower tuning cover 62 are connected by multiple tuning screws 63. A threaded hole is located at the center of the rectangular waveguide 2, and a tuning screw 21 is connected to the threaded hole. Since the rectangular waveguide 2 is a single-piece structure, the threaded hole is actually located at the center of the end cover position of the rectangular waveguide 2.

[0033] In this embodiment, each tuning screw 63 is connected to a locking nut at both ends. Tightening the locking nut causes deformation of the upper end cover 4 and the lower end cover 5, thereby changing the resonant frequency of the main cavity 1. The principle is that when the locking nut is tightened, the upper end cover 4, which is in close contact with the upper tuning cover 61, and the lower end cover 5, which is in close contact with the lower tuning cover 62, begin to be subjected to force. Under the action of the upper tuning cover 61 and the lower tuning cover 62, the distance between the upper end cover 4 and the lower end cover 5 changes due to elastic deformation. The distance change is different under different forces, thereby using the change in distance to achieve tuning of the frequency of the main cavity 1.

[0034] In this embodiment, the resonant frequency of the rectangular waveguide 2 is tuned by adjusting the screw depth of the tuning screw 21. As the tuning screw 21 is continuously screwed deeper into the rectangular waveguide 2, one end face of the tuning screw 21 and the inner wall surface of the rectangular waveguide 2 together form part of an adjustable short-circuit surface (the inner surface of the rectangular waveguide 2 away from the main cavity 1). As the tuning screw 21 is continuously screwed in, it is equivalent to the short-circuit surface continuously approaching the side wall of the main cavity 1, which is equivalent to the distance between the short-circuit surface and another short-circuit surface on the opposite side. By continuously reducing the size, frequency tuning of rectangular waveguide 2 was achieved.

[0035] It is worth noting that the tuning screw 21 engages with the threaded hole of the rectangular waveguide 2 through the thread, thereby ensuring the accuracy of frequency tuning through the precision of the thread, which can meet the working requirements of the resonant cavity. After the frequency tuning is completed, it can be sealed by welding with non-magnetic solder to the rectangular waveguide 2, that is, the connection interface between the tuning screw 21 and the rectangular waveguide 2 is sealed by non-magnetic solder to prevent microwave leakage.

[0036] Preferably, the end cap of the rectangular waveguide 2 has an M5 threaded hole at its center, and the tuning screw 21 is M5 with a length of 20mm, and the material can be titanium. It is understood that since the rectangular waveguide 2 and its end cap are designed as an integral structure, the end cap of the rectangular waveguide 2 refers to the location and structure that performs the function of the end cap, and will not be described further hereafter.

[0037] This invention integrates the rectangular waveguide 2 with its end cap, and achieves a sealed connection between the rectangular waveguide 2 and the main cavity 1 by welding. The resonant frequency of the rectangular waveguide 2 is tuned by adjusting the screw depth of the tuning screw 21. This changes the tuning method of the resonant frequency of the rectangular waveguide 2 and simplifies its structure. After tuning, the outer surfaces of the rectangular waveguide 2 and the tuning screw 21 are welded together using non-magnetic solder, completely eliminating the possibility of microwave leakage from the tuning screw 21. Finally, because this invention changes the tuning method of the resonant frequency of the rectangular waveguide 2, welding the rectangular waveguide 2 to the main cavity 1 becomes possible, avoiding the aging test required after using indium wire sealing for the rectangular waveguide 2. Therefore, this invention, through the tuning screw 21, not only solves the frequency tuning problem of the rectangular waveguide 2, but more importantly, it effectively solves the problems of low reliability and complex process associated with indium wire sealing.

[0038] In an alternative embodiment, the microwave cavity for the cold atom microwave clock further includes a semi-rigid cable 3, which is coupled to the rectangular waveguide 2 via an inner conductor probe.

[0039] like Figure 3 As shown, Figure 3 This is a schematic diagram of the main cavity provided in an embodiment of the present invention.

[0040] In one optional embodiment, the main cavity 1 is a cylindrical cavity, and small holes 11 are symmetrically provided on the side wall of the main cavity 1. Two rectangular waveguides 2 are respectively microwave coupled to the main cavity 1 through the small holes 11.

[0041] like Figure 4 and Figure 5 As shown, Figure 4 This is a structural cross-sectional view of the microwave cavity for a cold atom microwave clock provided in an embodiment of the present invention; Figure 5 This is provided by the embodiments of the present invention. Figure 4 A schematic diagram of the structure at point II.

[0042] In this embodiment, the upper end cover 4 and the lower end cover 5 are respectively provided at the upper and lower ends of the main cavity 1, and the center of the upper end cover 4 and the lower end cover 5 are both cylindrical cutoff waveguides. The upper cylindrical cutoff waveguide 41 and the lower cylindrical cutoff waveguide 51 are coaxially arranged and serve as cold atom channels.

[0043] In one optional embodiment, the upper cylindrical cutoff waveguide 41 is covered with a copper tube, and the copper tube outside the upper cylindrical cutoff waveguide 41 at least covers the free-flight region of the atom, that is, the entire path of the cold atom above the microwave cavity. This not only effectively shields stray GHz microwaves distributed in space, but also provides a uniform temperature distribution environment for the entire atom path, which is beneficial to improving the performance of the cold atom microwave clock. The lower cylindrical cutoff waveguide 51 is covered with a copper tube and extends to the detection region of the cold atom microwave clock. Setting the lower cylindrical cutoff waveguide 51 to have a sufficient extension length can avoid spatial stray microwave interference before the atom enters the detection region.

[0044] For example, the diameter of the upper cylindrical cutoff waveguide 41 is generally tens of mm, the height ranges from 60 to 90 mm, and the outer side is covered with a copper tube with an inner diameter range of 34 to 44 mm and a length range of 400 to 450 mm.

[0045] For example, the length of the lower cylindrical cutoff waveguide 51 ranges from 250 mm to 300 mm.

[0046] In an optional embodiment, the lower cylindrical cutoff waveguide 51 has a positioning disk 511 in the middle and a fixing disk 512 at the end. The positioning disk 511 is used to ensure that the entire cavity is parallel to the vertical direction. The fixing disk 512 has multiple connecting holes, through which it connects to other components of the cold atom microwave clock. For example, both the positioning disk 511 and the fixing disk 512 can be configured as circular disks.

[0047] To completely eliminate the possibility of GHz microwave leakage from the microwave cavity, both the upper end cover 4 and the lower end cover 5 are welded to the main cavity 1. During the welding process, the end covers are usually fixed to the cavity using clamps. After welding is completed, the clamps are removed to release stress, but the resonant frequency of the resonant cavity usually changes during this process.

[0048] like Figure 6 As shown, Figure 6 This is a schematic diagram of the frequency tuning component provided in this embodiment of the invention. The resonant frequency can be tuned using the frequency tuning component 6. The frequency tuning component 6 includes an upper tuning cover 61, a lower tuning cover 62, and a tuning screw 63. Both ends of the tuning screw 63 are equipped with locking nuts (not shown in the figure). By tightening the locking nuts, the upper tuning cover 61 presses against the upper end cover 4, and the lower tuning cover 62 presses against the lower end cover 5, thereby subjecting the end covers of the main cavity 1 to force. Depending on the force applied to the end covers, the resonant frequency of the resonant cavity will also change. Thus, by pressing the end covers, the resonant frequency is tuned until the microwave cavity's requirements for the cavity resonant frequency are met.

[0049] In one alternative embodiment, the upper tuning cover 61 is a square plate with a through hole in the center and threaded holes at the four corners for connecting the tuning screw 63.

[0050] For example, the upper tuning cover 61 is a square titanium plate with a circular hole in the center and threaded holes at each of the four corners. Preferably, the upper tuning cover 61 is a square titanium plate with a length and width of 110mm and a thickness of 5mm. A circular hole with a diameter of 35.5mm is located in the center of the square plate for the passage of the upper cylindrical cutoff waveguide 41 and the lower cylindrical cutoff waveguide 51. Four M6 threaded holes are evenly distributed at the four corners of the square plate. The tuning screw 63 has a length of 95mm.

[0051] In one alternative embodiment, the lower tuning cover 62 is a square plate with a U-shaped groove for easy installation, and the four corners of the lower tuning cover 62 are provided with threaded holes corresponding to the upper tuning cover 61 to connect the tuning screw 63.

[0052] Preferably, the lower tuning cover 62 is a square titanium plate with a length and width of 110mm and a thickness of 5mm. It has a U-shaped groove in the middle and four M6 threaded holes at the four corners. Correspondingly, there are also four tuning screws 63.

[0053] Preferably, the upper tuning cover 61, the lower tuning cover 62, the four tuning screws 63 and the eight locking nuts at both ends are all made of titanium.

[0054] It is worth noting that, through the frequency tuning component 6, even if the resonant frequency of the main cavity 1 changes after welding, the upper end cover 4 and the lower end cover 5 can be deformed by tightening the locking nut, thereby changing the resonant frequency of the main cavity 1 and achieving quick adjustment. Therefore, there is no need to use traditional indium wire sealing and set up aging tests accordingly.

[0055] For example, the main cavity 1, the rectangular waveguide 2, the upper end cover 4, and the lower end cover 5 can all be made of oxygen-free copper material.

[0056] For example, the copper tube covering the upper cylindrical cutoff waveguide 41 can also be made of titanium; the positioning disk 511 and fixing disk 512 of the lower cylindrical cutoff waveguide 51 can also be made of titanium.

[0057] For example, the upper tuning cover 61, the lower tuning cover 62, the tuning screw 63, and the locking nut can all be made of titanium.

[0058] Understandably, existing cold atom clocks use microwave cavities that are sealed with indium wire and their upper and lower end caps, then secured with screws. This sealing method facilitates the removal of the cavity cap to adjust the resonant frequency. However, in terms of suppressing microwave leakage, indium wire sealing is clearly less reliable than directly welding the cavity cap to the cavity. Furthermore, since cold atom clocks operate in a high-vacuum environment, microwave cavities sealed with indium wire require aging tests to verify their integrity and prevent deformation of the indium wire during high-temperature baking, which could affect the resonant frequency of the cavity. This undoubtedly increases the complexity of the resonant cavity development process. In contrast, the rectangular waveguide 2, upper end cap 4, and lower end cap 5 of this invention are directly welded to the main cavity 1, which not only completely prevents microwave leakage in the microwave cavity but also eliminates the need for aging tests, offering high reliability and ease of operation.

[0059] Specifically, in the microwave cavity of the cold atom microwave clock of the present invention, the end cap of the main cavity 1 is welded to the main cavity 1, and the end cap of the rectangular waveguide 2 is welded to the rectangular waveguide 2 itself using laser welding for fixation and sealing. Frequency tuning of the main cavity 1 is then achieved using the frequency tuning component 6, while frequency tuning of the rectangular waveguide 2 is achieved using the tuning screw 21. In contrast, in existing microwave cavities, screws are used to fix the end cap of the main cavity to the main cavity and the end cap of the rectangular waveguide to the rectangular waveguide. During frequency tuning, the end cap is then polished with sandpaper. Specifically, the cavity cap is polished, then fixed to the cavity, and the resonant frequency is tested to ensure it meets the requirements. Generally, the process of polishing and testing the resonant frequency may be repeated several times, requiring repeated disassembly and adjustment of the end cap. It is precisely this need for repeated disassembly and adjustment that prevents the use of fixing and sealing methods such as welding in existing technologies. Furthermore, due to the use of screws for fixation, indium wire sealing is necessary at the connection points to prevent microwave leakage. However, using indium wire sealing introduces new problems. Since cold atom microwave cavities operate in a high-vacuum environment, microwave cavities using indium wire sealing require high- and low-temperature aging tests before high-vacuum evacuation, and must be left to stand for at least a month after the tests to observe any changes in the cavity frequency. This process undoubtedly significantly prolongs the development time of the microwave cavity. In other words, there is an irreconcilable contradiction in existing microwave cavities: indium wire sealing requires a lengthy aging test process and has relatively low reliability, while using non-removable sealing connections such as welding completely destroys the microwave cavity's tuning capability.

[0060] In other words, the microwave cavity for a cold atom microwave clock of the present invention uses laser welding to fix and seal the end cap of the main cavity 1 to the main cavity 1 and the end cap of the rectangular waveguide 2 to the rectangular waveguide 2 itself. This fundamentally avoids the unreliability problems caused by indium wire sealing and eliminates the need for aging tests, thus shortening the development time of the microwave cavity. Furthermore, the tuning assembly 6 is used to achieve frequency tuning of the main cavity 1, and the tuning screw 21 is used to achieve frequency tuning of the rectangular waveguide 2. Thus, through the synergy of dual tuning and laser welding, repeated disassembly, grinding, and debugging are no longer required, further shortening the development time of the microwave cavity, simplifying the assembly and tuning process, and facilitating standardization and industrialization.

[0061] The microwave cavity for a cold atom microwave clock of the present invention has a main cavity body and a rectangular waveguide sealed by welding. At the same time, the upper end cover and the lower end cover are also welded to the main cavity body. The welding seal replaces the traditional indium wire seal, thus eliminating the need to design high and low temperature aging tests and avoiding the risk of aging and deformation of indium wire seals. It effectively prevents microwave leakage, simplifies the structure, improves sealing reliability, and shortens the development time of microwave cavity.

[0062] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations are intended to cover non-exclusive inclusion, such that an article or device comprising a list of elements includes not only those elements but also other elements not expressly listed. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device comprising said element. Terms such as "connected" or "linked" are not limited to physical or mechanical connections but can include electrical connections, whether direct or indirect. The orientations or positional relationships indicated by terms such as "upper," "lower," "left," and "right" are based on the orientations or positional relationships shown in the accompanying drawings and are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element 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.

[0063] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A microwave cavity for a cold atom microwave clock, characterized in that, The utility model relates to a cold atom microwave cavity, comprising: a main cavity, two rectangular waveguides are symmetrically arranged on the side wall and are sealed by welding; an upper end cover is welded on the upper end of the main cavity, an extended upper cylindrical cutoff waveguide is arranged at the center of the upper end cover, a lower end cover is welded on the lower end of the main cavity, and an extended lower cylindrical cutoff waveguide is arranged at the center of the lower end cover; a frequency tuning assembly, comprising an upper tuning cover and a lower tuning cover, the upper tuning cover is overlaid on the upper end cover, the lower tuning cover is overlaid on the lower end cover, and the upper tuning cover and the lower tuning cover are connected by a plurality of tuning screws; a threaded hole is arranged at the center of the rectangular waveguide, and a tuning screw is connected to the threaded hole; wherein a locking nut is connected to each end of the tuning screw, the upper end cover and the lower end cover are deformed by tightening the locking nut, so as to change the resonant frequency of the main cavity; the resonant frequency of the rectangular waveguide is tuned by adjusting the screwing depth of the tuning screw.

2. The microwave cavity for a cold atom microwave clock of claim 1, wherein, The side wall of the main cavity is symmetrically provided with a small hole, and the two rectangular waveguides are respectively coupled to the main cavity through the small hole.

3. The microwave cavity for a cold atom microwave clock of claim 1, wherein, It also includes a semi-rigid cable, which is coupled to the rectangular waveguide through an inner conductor probe.

4. The microwave cavity for a cold atom microwave clock of claim 1, wherein, The upper cylindrical cutoff waveguide and the lower cylindrical cutoff waveguide are coaxially arranged and serve as a cold atom channel.

5. The microwave cavity for a cold atom microwave clock of claim 1, wherein, The upper cylindrical cutoff waveguide is wrapped with a copper pipe, and the copper pipe outside the upper cylindrical cutoff waveguide covers at least the atom free flight area; the lower cylindrical cutoff waveguide is wrapped with a copper pipe, and the lower cylindrical cutoff waveguide extends to the detection area of the cold atom microwave clock.

6. The microwave cavity for a cold atom microwave clock of claim 1, wherein, The middle part of the lower cylindrical cutoff waveguide is provided with a positioning disc, and the end part is provided with a fixing disc, and a plurality of connecting holes are arranged on the fixing disc.

7. The microwave cavity for a cold atom microwave clock of claim 1, wherein, The upper tuning cover is a square plate, and a through hole is arranged in the middle part; the lower tuning cover is a square plate, and a U-shaped groove is arranged on the upper part; a threaded hole is arranged at the four corners of the upper tuning cover and the lower tuning cover to connect the tuning screw.

8. The microwave cavity for a cold atom microwave clock of claim 1, wherein, The tuning screw is threadedly connected to the rectangular waveguide, and is sealed by non-magnetic soldering after tuning.

9. The microwave cavity for a cold atom microwave clock of claim 1, wherein, The main cavity, the rectangular waveguide, the upper end cover and the lower end cover are made of oxygen-free copper material.

10. The microwave cavity for a cold atom microwave clock of claim 1, wherein, The upper tuning cover, the lower tuning cover, the tuning screw and the locking nut are made of titanium material.

Images