Miniaturized vacuum system for atomic gravity gradiometer

Abstract

The invention discloses a miniaturized vacuum system for an atomic gravity gradiometer, which comprises an upper vacuum cavity, an upper getter I, an upper getter II, an ion pump I, an ion pump II, an upper copper pipe, an upper atomic source, a lower vacuum cavity, a lower getter I, a lower getter II, a lower copper pipe and a lower atomic source, the vacuum system can be divided into an upper atom trapping area, an upper interference area, an upper detection area, a cavity connecting area, a lower atom trapping area, a lower interference area and a lower detection area according to functional area division, and the upper detection area and the lower detection area are each provided with at least one detection window used for detecting the number of atoms. The mode of combining the getter and the ion pump is adopted to replace a large-size combination pump, the size of the vacuum system of the atomic gravity gradiometer is remarkably reduced, meanwhile, by reasonably distributing the positions of the pump sets, the vacuum degree consistency of the upper cavity and the lower cavity is effectively improved, the common-mode rejection effect of the atomic gravity gradiometer is enhanced, and the gravity gradient measurement precision is improved.

Description

Technical Field

[0001] This invention belongs to the field of atomic interferometer technology, specifically relating to a miniaturized vacuum system for an atomic gravity gradiometer. Background Technology

[0002] Currently, atomic interferometers have been successfully applied in measuring inertial quantities such as gravitational acceleration, gravitational gradient, and rotational angular velocity. Among these, the atomic interferometer used to measure gravitational acceleration has become a commercially available product—the atomic gravimeter. Compared to the atomic gravimeter, the atomic interferometer used to measure the gravitational gradient—the atomic gravity gradiometer—is more complex, larger, and heavier. Therefore, most existing atomic gravity gradiometers are still in the laboratory engineering prototype stage. To promote the development of atomic gravity gradiometers into commercial products, the first step is to improve the miniaturization of the vacuum system.

[0003] An atomic gravity gradiometer typically consists of two atomic interferometers. The vacuum system is quite long, requiring a larger and faster vacuum pump assembly to maintain the vacuum level, resulting in a significant system size and weight. Furthermore, these pump assemblies are magnetic. Placing them inside the magnetic shielding of the vacuum system can interfere with the atomic interferometry process, introducing measurement errors. Placing them outside the magnetic shielding can cause inconsistent vacuum levels between the two interferometers, reducing the system's common-mode suppression and affecting the gravity gradient measurement results.

[0004] The large size of the vacuum system of the atomic gravity gradiometer also requires more turns of the magnetic field coil and a larger driving current, which increases the size and complexity of the system. Summary of the Invention

[0005] The purpose of this invention is to provide a miniaturized vacuum system for atomic gravity gradiometers, solving the problems of large size and weight and low miniaturization of existing atomic gravity gradiometers, and promoting the development of atomic gravity gradiometers from the laboratory to commercial products.

[0006] The technical solution adopted by this invention to solve its technical problem is: a miniaturized vacuum system for an atomic gravity gradiometer, comprising an upper vacuum cavity and a lower vacuum cavity connected to each other, and ion pump one and ion pump two symmetrically arranged at the connection area of ​​the cavity at the same height. The upper vacuum cavity has an upper detection window located in the upper detection area above the connection. The upper vacuum cavity is sequentially arranged with an upper copper tube located in the upper interference area above the detection window, and upper getter one and upper getter two symmetrically arranged at the same height above the upper copper tube. An upper atomic source is arranged in the upper atomic cage area at the top of the upper vacuum cavity. The lower vacuum cavity has a lower atomic source located in the lower atomic cage area below the connection area of ​​the cavity at the connection. The lower vacuum cavity is sequentially arranged with lower getter one and lower getter two symmetrically arranged at the same height in the lower interference area below the lower atomic source, and a lower detection window is arranged in the lower detection area below the lower copper tube.

[0007] The miniaturized vacuum system for an atomic gravity gradiometer has two ion pumps, one and two, designed with double-layer magnetic shielding shells. They are installed in the cavity connection area by non-magnetic welding or flange connection. The two ion pumps are placed symmetrically at the same height, and the placement height is located at the center of the entire vacuum system.

[0008] The miniaturized vacuum system for an atomic gravity gradiometer has two getters, one and two, installed in the lower interference region by non-magnetic welding or flange connection. The two getters are placed symmetrically at the same height. To ensure the consistency of the vacuum level of the entire vacuum system, the distance from the upper getter one / upper getter two to the ion pump one / ion pump two is required to be equal to the distance from the lower getter one / lower getter two to the ion pump one / ion pump two.

[0009] The miniaturized vacuum system for an atomic gravity gradiometer is described above, in which the upper getter 1, upper getter 2, lower getter 1, and lower getter 2 are all made of non-magnetic materials and are non-magnetic as a whole.

[0010] The miniaturized vacuum system for an atomic gravity gradiometer has an upper vacuum chamber and a lower vacuum chamber made of non-magnetic materials and connected by non-magnetic welding or flange connection.

[0011] The miniaturized vacuum system for an atomic gravity gradiometer is described above. The shells of the upper and lower atomic sources are both made of non-magnetic materials and are completely non-magnetic. They are installed to the upper and lower vacuum chambers respectively by non-magnetic welding or flange connection.

[0012] The miniaturized vacuum system for an atomic gravity gradiometer has an upper atomic confinement zone and a lower atomic confinement zone that are octagonal columnar structures, each with a light-transmitting window on one of its six faces, including at least six light-transmitting windows: light-transmitting window one, light-transmitting window two, light-transmitting window three, light-transmitting window four, light-transmitting window five, and light-transmitting window six.

[0013] The miniaturized vacuum system for an atomic gravity gradiometer comprises six parallel windows arranged in pairs. Two of these windows house two anti-Helmholtz coils. Each of the six windows receives a laser beam of specific frequency, polarization, and power to generate the optical field required for atomic trapping. The anti-Helmholtz coils receive currents of specific magnitude and direction to generate the magnetic field gradient needed for atomic trapping, thus forming a three-dimensional magneto-optical trap for atomic confinement.

[0014] The miniaturized vacuum system for an atomic gravity gradiometer comprises two anti-Helmholtz coils, one and two, both fixed to the upper / lower vacuum chamber via structural components. By using an embedded design to reduce the center-to-center distance of the coils, a smaller size, fewer turns, and a weaker current are achieved to generate the magnetic field gradient required for atomic trapping.

[0015] The miniaturized vacuum system for an atomic gravity gradiometer is described above. Its upper and lower copper tubes are evacuated by an external vacuum pump. After the vacuum level reaches the experimental requirements, the copper tubes are sealed by pressure to achieve a non-magnetic seal.

[0016] The beneficial effects of this invention are:

[0017] This invention uses a combination of getter and ion pump to replace the large-volume composite pump, which significantly reduces the volume of the vacuum system of the atomic gravity gradiometer. At the same time, by rationally distributing the pump group positions, it effectively improves the consistency of vacuum in the upper and lower cavities, enhances the common-mode suppression effect of the atomic gravity gradiometer, and improves the accuracy of gravity gradient measurement.

[0018] The ion pump of this invention is designed with a double-layer magnetic shielding structure. Other components, such as getter and atomic source, are made of non-magnetic materials and are assembled through non-magnetic welding and other processes. This minimizes the bias magnetic field in the vacuum system and effectively reduces the error of the gravity gradient measurement system.

[0019] The anti-Helmholtz coil of this invention adopts an embedded design, which minimizes the center distance of the coil, reduces the required operating current, effectively reduces the volume of the vacuum system, and lowers the complexity of the drive system. Attached Figure Description

[0020] Figure 1 A schematic diagram of a vacuum system provided in an embodiment of the present invention;

[0021] Figure 2This is a schematic cross-sectional view of a vacuum system provided in an embodiment of the present invention;

[0022] Figure 3 This is a side view cross-sectional schematic diagram of the atomic prison area of ​​the vacuum system provided in an embodiment of the present invention.

[0023] The labels in the attached figures are as follows: 11—Upper vacuum chamber, 12—Lower vacuum chamber, 21—Upper getter 1, 22—Upper getter 2, 23—Lower getter 1, 24—Lower getter 2, 31—Ion pump 1, 32—Ion pump 2, 41—Upper copper tube, 42—Lower copper tube, 51—Upper atomic source, 52—Lower atomic source, 611—Light transmission window 1, 612—Light transmission window 2, 613—Light transmission window 3, 614—Light transmission window 4, 615—Light transmission window 5, 616—Light transmission window 6, 71—Upper detector window, 72—Lower detector window, 81—Inverse Helmholtz coil 1, 82—Inverse Helmholtz coil 2. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to the accompanying drawings.

[0025] like Figure 1 As shown, this embodiment provides a miniaturized vacuum system for an atomic gravity gradiometer, including an upper vacuum chamber 11, an upper getter 1 21, an upper getter 2 22, an ion pump 1 31, an ion pump 2 32, an upper copper tube 41, an upper atomic source 51, a lower vacuum chamber 12, a lower getter 1 23, a lower getter 2 24, a lower copper tube 42, and a lower atomic source 52.

[0026] like Figure 2 As shown, the vacuum system can be divided into an upper atomic confinement zone, an upper interference zone, an upper detection zone, a cavity connection zone, a lower atomic confinement zone, a lower interference zone, and a lower detection zone according to functional areas. Both the upper and lower detection zones are equipped with at least one detection window for detecting the number of atoms. Specifically, this includes an upper detection window 71 located above the connection point on the upper vacuum cavity 11 and a lower detection window 72 located on the lower copper tube 42.

[0027] The upper vacuum chamber 11 and the lower vacuum chamber 12 are made of pure titanium and are connected by non-magnetic welding. Requirements are set for the coaxiality of the upper and lower chambers after welding. An inspection process is set after welding to ensure the consistency of the atomic interference process of the two interferometers.

[0028] Ion pump 1 31 and ion pump 2 32 are located in the cavity connection area. The two ion pumps are placed symmetrically at the same height h0, and the placement height is located at the center of the entire vacuum system. They are installed to the upper vacuum cavity 11 by means of flange connection.

[0029] The housings of the upper getter 1 21, upper getter 2 22, lower getter 1 23, and lower getter 2 24 are all made of pure titanium and are non-magnetic. Upper getter 1 21 and upper getter 2 22 are positioned in the upper interference region, symmetrically placed at the same height h1, and installed to the upper vacuum chamber 11 using non-magnetic welding. Lower getter 1 23 and lower getter 2 24 are positioned in the lower interference region, symmetrically placed at the same height h2, and installed to the lower vacuum chamber 12 using non-magnetic welding. To ensure the consistency of the vacuum level throughout the system, the distance from the upper getter to the ion pump must be equal to the distance from the lower getter to the ion pump, i.e., (h1 + h2) / 2 = h0.

[0030] The shells of both the upper atomic source 51 and the lower atomic source 52 are made of pure titanium and are non-magnetic. The upper atomic source 51 and the lower atomic source 52 are respectively located in the upper atomic prison restricted area and the lower atomic prison restricted area, and are installed to the upper vacuum cavity 11 and the lower vacuum cavity 12 by non-magnetic welding.

[0031] The upper copper tube 41 and the lower copper tube 42 are respectively set in the upper interference region and the lower interference region. When evacuating, a vacuum pump is connected to the copper tube. When the vacuum degree reaches the experimental requirements, the copper tube is pressed to achieve non-magnetic sealing.

[0032] In the technical solution of this embodiment, a combination of getter and ion pump is used instead of a large-volume composite pump, which can reduce the maximum diameter of the vacuum system to within Φ20cm, significantly reducing the volume of the atomic gravity gradient instrument vacuum system.

[0033] Meanwhile, in the technical solution of this embodiment, by reasonably distributing the pump group positions, the consistency of vacuum degree between the upper and lower cavities is effectively improved, the common mode suppression effect of the atomic gravity gradiometer is enhanced, and the accuracy of gravity gradient measurement is improved.

[0034] In the technical solution of this embodiment, both ion pump 31 and ion pump 32 are designed with double-layer magnetic shielding shells. Other components and screws in the vacuum system are made of non-magnetic materials. Therefore, the bias magnetic field inside the vacuum system is extremely weak, which effectively reduces the measurement system error.

[0035] like Figure 2 and 3 As shown, the upper and lower atomic confinement areas are octagonal prism structures, each with at least six transparent windows (611, 612, 613, 614, 615, and 616) on its six faces. The windows are paired and parallel. A pair of anti-Helmholtz coils (81 and 82) are embedded within two of these faces. The upper and lower detection areas each have an upper detection window (71) and a lower detection window (72) for detecting the number of atoms. The upper and lower cavity windows are configured similarly to the coils and will not be described again.

[0036] By inputting a laser beam of specific frequency, polarization, and power into each of the light-transmitting windows (611, 612, 613, 614, 615, and 616), the optical field required for atomic trapping is generated. By inputting currents of specific magnitude and direction into anti-Helmholtz coil 81 and anti-Helmholtz coil 82, respectively, the magnetic field gradient required for atomic trapping is generated, thus forming a three-dimensional magneto-optical trap and realizing atomic trapping.

[0037] Generally, the greater the center distance between the anti-Helmholtz coil 1 (81) and the anti-Helmholtz coil 2 (82), the larger the size of the coil, the more turns, and the stronger the current required to generate the same magnetic field gradient in the center of the atomic prison. This also causes severe heat generation, and may even require water cooling to cool the coil, resulting in an increased system size and a more complex drive system.

[0038] In the technical solution of this embodiment, the coil embedded design can minimize the distance between the first anti-Helmholtz coil 81 and the second anti-Helmholtz coil 82. The coil can be smaller in size, with fewer turns and weaker current, effectively reducing the system size and the complexity of the drive system.

[0039] Those skilled in the art will readily understand that the above description is merely a preferred use case of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A miniaturized vacuum system for an atomic gravity gradiometer, characterized by: The utility model relates to a vacuum system, including mutually connected upper vacuum cavity (11) and lower vacuum cavity (12), and ion pump one (31) and ion pump two (32) are symmetrically arranged at the connecting place along the same height, the upper vacuum cavity (11) is opened with the upper detection window (71) located the connecting place top, and the upper vacuum cavity (11) is sequentially provided with the upper copper pipe (41) and symmetrically arranged upper getter one (21) and upper getter two (22) at the detection window (71) top along the same height outside, and the upper atomic trapping area of upper vacuum cavity (11) top is provided with upper atom source (51), and the lower atomic trapping area of lower vacuum cavity (12) located the connecting place below is provided with lower atom source (52), and the lower vacuum cavity (12) is sequentially provided with lower getter one (23) and lower getter two (24) and lower copper pipe (42) at the same height symmetrically below lower atom source (52) outside, and the lower vacuum cavity (12) is opened with the lower detection window (72) located lower copper pipe (42) below.

2. A miniaturized vacuum system for an atomic gravity gradiometer according to claim 1, characterized in that The ion pump one (31) and ion pump two (32) are provided with double-layer magnetic shielding shell, are installed to the cavity connecting area through the mode of non-magnetic welding or flange connection and are placed in the center of vacuum system.

3. A miniaturized vacuum system for an atomic gravity gradiometer according to claim 2, characterized in that The lower getter one (23) and lower getter two (24) are installed to the lower interference area through the mode of non-magnetic welding or flange connection, and the distance from upper getter one (21) / upper getter two (22) to ion pump one (31) / ion pump two (32) is equal to the distance from lower getter one (23) / lower getter two (24) to ion pump one (31) / ion pump two (32).

4. A miniaturized vacuum system for an atomic gravity gradiometer according to claim 1 or 2 or 3, characterized in that, The upper getter one (21), upper getter two (22), lower getter one (23) and lower getter two (24) are all made of non-magnetic material.

5. A miniaturized vacuum system for an atomic gravity gradiometer according to claim 4, characterized in that The upper vacuum cavity (11) and lower vacuum cavity (12) are made of non-magnetic material and are connected through the mode of non-magnetic welding or flange butt joint.

6. A miniaturized vacuum system for an atomic gravity gradiometer according to claim 5, characterized in that The shell of upper atom source (51) and lower atom source (52) is made of non-magnetic material and is installed to upper vacuum cavity (11) and lower vacuum cavity (12) through the mode of non-magnetic welding or flange connection.

7. A miniaturized vacuum system for an atomic gravity gradiometer according to claim 6, characterized in that The upper atomic trapping area and lower atomic trapping area are octagonal column structures, including light transmission window one (611), light transmission window two (612), light transmission window three (613), light transmission window four (614), light transmission window five (615) and light transmission window six (616).

8. A miniaturized vacuum system for an atomic gravity gradiometer according to claim 7, characterized in that The windows are opposite and parallel, and two of them have anti-Helmholtz coil one (81) and anti-Helmholtz coil two (82).

9. A miniaturized vacuum system for an atomic gravity gradiometer according to claim 8, characterized in that The anti-Helmholtz coil one (81) and anti-Helmholtz coil two (82) are fixed on upper vacuum cavity (11) / lower vacuum cavity (12) through structural members.

10. A miniaturized vacuum system for an atomic gravity gradiometer according to claim 8, characterized in that, The upper copper pipe (41) and lower copper pipe (42) are vacuumized through external vacuum pump, and are sealed by copper pipe after reaching the experimental requirement of vacuum degree.

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