A cylindrical sapphire atomic gas chamber shell and its preparation method
The sapphire atomic gas chamber shell was prepared by cutting, grinding, polishing and non-contact heating, which solved the problem of sealing sapphire material and achieved a cylindrical gas chamber with high airtightness and low helium leakage rate, which is suitable for quantum instruments.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- BEIJING INST OF AEROSPACE CONTROL DEVICES
- Filing Date
- 2023-06-15
- Publication Date
- 2026-07-17
Smart Images
Figure CN116892956B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of atomic gas chamber manufacturing technology, and in particular to a cylindrical sapphire atomic gas chamber shell and its preparation method. Background Technology
[0002] The atomic gas chamber is a core component of quantum instruments such as gyroscopes, magnetometers, and atomic clocks, and its performance directly affects the final accuracy of these instruments. Atomic gas chambers are typically cubic / cylindrical structures made of glass. The usual operating procedure involves first evacuating the empty atomic gas chamber shell, then filling it with an alkali metal and a filling gas, and finally sealing the chamber by melting the glass tube with a flame. Currently, commonly used materials for atomic gas chambers include borosilicate glass, quartz glass, and high-alumina silicate glass.
[0003] Sapphire, an α-Al₂O₃ single crystal, possesses excellent physicochemical properties such as high strength, high temperature resistance, corrosion resistance, and wear resistance. Combined with its good optical properties, it is increasingly widely used in high-temperature and high-pressure devices, special optical windows, and missile fairings. Using sapphire to fabricate atomic chamber shells offers advantages such as a low coefficient of thermal expansion, high temperature resistance (2000℃), and high helium permeability. The industry has high hopes for sapphire atomic chambers and has an urgent application demand. However, as a crystal, sapphire cannot be processed into shells using the flame melting method common to other glasses. Summary of the Invention
[0004] The purpose of this invention is to solve the problem of difficult processing of sapphire atomic gas chambers, and to provide a cylindrical sapphire atomic gas chamber shell and its preparation method, which solves the problem of sealing the sapphire shell during processing when sapphire is used as the raw material for atomic gas chamber shells.
[0005] The above-mentioned objective of this invention is mainly achieved through the following technical solution: a method for preparing a cylindrical sapphire atomic gas chamber shell, comprising the following steps:
[0006] (1) Cut the first sapphire wafer and the second sapphire wafer to serve as the light-transmitting surface of the atomic gas chamber, and drill holes in the first sapphire wafer;
[0007] (2) Cut the sapphire tube to serve as the main body of the atomic gas chamber;
[0008] (3) Cut the first glass transition ring for the transition between the sapphire tube and the first sapphire wafer, and cut the second glass transition ring for the transition between the sapphire tube and the second sapphire wafer.
[0009] (4) Grinding, polishing and shaping of the first sapphire wafer, the second sapphire wafer, the sapphire tube and the first glass transition ring and the second glass transition ring;
[0010] (5) Limit the air chamber shell, and stack it in the following order: first sapphire disc - second glass transition ring - sapphire tube - second glass transition ring - second sapphire disc, and apply prestress.
[0011] (6) Non-contact heating of the air chamber shell;
[0012] (7) After cooling to room temperature, check the regularity of the air chamber shell, and discard the air chamber shells that have not been welded or have been deformed too much. The air chamber shells that have qualified regularity can proceed to the next step.
[0013] (8) Use a flame to fuse the hole in the first sapphire wafer with the filling tube;
[0014] (9) Connect the filling tube to the vacuum system and check the air tightness. If the vacuum leakage rate meets the preset requirements, remove the air chamber shell with qualified air tightness, clean the inner and outer walls of the air chamber shell, and dry it.
[0015] (10) Check the light transmittance of the light-transmitting surface of the air chamber shell. If the light transmittance meets the preset requirements, check the regularity of the air chamber shell. If the regularity meets the preset requirements, the air chamber shell is qualified. If at least one of the air tightness, light transmittance, or regularity does not meet the requirements, the air chamber shell is unqualified and the unqualified air chamber shell is rejected.
[0016] Furthermore, the diameter of the hole drilled in the first sapphire wafer is 1.5–2.5 mm;
[0017] The outer diameter of the filling tube is 2.5–3.5 mm, the inner diameter is 1.5–2.5 mm, and the length is 30–40 mm.
[0018] Furthermore, in step (3), the first glass transition ring and the second glass transition ring are both made of DM308 electronic material, and the thickness of the first glass transition ring and the second glass transition ring is 0.3 to 0.6 mm.
[0019] Furthermore, in step (4), the grinding, polishing, and shaping of the first sapphire wafer, the second sapphire wafer, the sapphire tube, the first glass transition ring, and the second glass transition ring are required to have a surface profile accuracy better than λ / 4, a surface roughness ≤10nm, and a light transmittance of ≥85%@0.15~7.5μm in the light-transmitting area of the first sapphire wafer and the second sapphire wafer.
[0020] Furthermore, in step (5), a custom tooling made of polyimide is used to limit the gas chamber shell, and a prestress value of 0.12 to 0.15 MPa is applied.
[0021] Furthermore, in step (6), the air chamber shell is heated non-contactly using a high-frequency induction heater. The target heating temperature is 720–750°C, and the heating time is 6–8 minutes.
[0022] Furthermore, in step (9), the air tightness of the gas chamber shell is tested using a helium mass spectrometer leak detector.
[0023] Furthermore, in step (9), the inner and outer walls of the air chamber shell are cleaned using an ultrasonic cleaner with a working frequency of ≤40kHz.
[0024] Furthermore, a cylindrical sapphire atomic gas chamber shell is provided, comprising a stacked structure consisting of a first sapphire disc, a first glass transition ring, a sapphire tube, a second glass transition ring, and a second sapphire disc. The first sapphire disc is provided with a through hole, which is fused to the filling tube.
[0025] Furthermore, the sapphire tube, the first sapphire wafer, and the second sapphire wafer are made of α-Al2O3 single crystal, the first glass transition ring and the second glass transition ring are made of DM308 electronic glass, and the filling tube is made of Schott 8436 glass.
[0026] Compared with the prior art, the present invention has the following advantages:
[0027] (1) The cylindrical sapphire atomic gas chamber shell prepared by this method solves the sealing problem of sapphire shell by using a high-frequency induction heater for non-contact heating of the gas chamber shell, achieving high gas tightness sealing with an overall leakage rate better than 1×10⁻⁶. –12 Pa·m 3 / s, which can meet the requirements for filling atomic gas chambers;
[0028] (2) The cylindrical sapphire atomic gas chamber shell prepared by this method can give full play to the excellent properties of sapphire material. It has the advantages of high regularity, good light transmittance and low helium leakage rate. The gas chamber can work for a long time under the conditions of 400-500℃. Attached Figure Description
[0029] Figure 1 This is a flowchart illustrating the fabrication process of a cylindrical sapphire atomic gas chamber shell according to the present invention.
[0030] Figure 2(a) is a schematic diagram of the components of a cylindrical sapphire atomic gas chamber shell according to the present invention;
[0031] Figure 2(b) is a schematic diagram of the forming of a cylindrical sapphire atomic gas chamber shell in this invention. Detailed Implementation
[0032] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments:
[0033] A cylindrical sapphire atomic gas chamber shell and its preparation method are characterized by the following steps:
[0034] (1) Cut the first sapphire disc and the second sapphire disc according to the size of the gas chamber to be processed, and use them as the light-transmitting surface of the atomic gas chamber. Drill holes in the first sapphire disc with a diameter of 2mm for connecting the filling tube.
[0035] (2) Cut the sapphire tube according to the size of the finished gas chamber to be processed, and use it as the main body of the atomic gas chamber;
[0036] (3) Cut the first glass transition ring according to the size of the finished gas chamber to be processed, for the transition between the sapphire tube and the first sapphire wafer, and cut the second glass transition ring for the transition between the sapphire tube and the second sapphire wafer.
[0037] (4) Grinding, polishing and shaping of the first sapphire wafer, the second sapphire wafer, the sapphire tube and the first glass transition ring and the second glass transition ring, requiring the surface accuracy of the mating surface to be ≥λ / 4 and the surface roughness to be ≤10nm. The light transmittance of the light-transmitting area of the first sapphire wafer and the second sapphire wafer is ≥85%@0.15~7.5μm.
[0038] (5) Use custom tooling to limit the gas chamber shell components. The arrangement order is: first sapphire disc - first glass transition ring - sapphire tube - second glass transition ring - second sapphire disc. Apply prestress with a stress value range of 0.12 to 0.15 MPa.
[0039] (6) Use a high-frequency induction heater to perform non-contact heating on the air chamber shell clamped by the customized tooling, with a target heating temperature of 720-750℃ and a heating time of 6-8 minutes;
[0040] (7) After cooling to room temperature, remove the air chamber shell from the custom tooling, check the regularity, and discard the air chamber shells that have not been welded or have been deformed too much. The air chamber shells that have qualified regularity can proceed to the next step.
[0041] (8) Use a flame to fuse the drilled position of the first sapphire wafer with the filling tube for subsequent filling of alkali metals and gas.
[0042] (9) Connect the filling tube to the vacuum system and check the airtightness. The vacuum leakage rate should be better than 1×10⁻⁶. –12 Pa·m 3 Only when the air chamber shell with a capacity of / s is qualified can the next step of operation be carried out;
[0043] (10) Remove the air chamber shell with qualified air tightness, use an ultrasonic cleaner to clean the inner and outer walls of the air chamber shell, and dry it.
[0044] (11) Check the light transmittance of the light-transmitting surface of the air chamber shell. The light transmittance is ≥85%@0.15~7.5μm to be qualified before proceeding to the next step.
[0045] (12) Check the regularity of the gas chamber shell; when the regularity, air tightness and light transmittance of the gas chamber shell are all qualified, the prepared gas chamber shell is qualified and can be used for the preparation of atomic gas chambers; otherwise, the prepared gas chamber shell is unqualified and the unqualified gas chamber shell is rejected.
[0046] In step (3) above, the first glass transition ring and the first glass transition ring are both made of DM308 electronic glass. The thickness of the first glass transition ring and the first glass transition ring is 0.3 to 0.6 mm, and there are no obvious chipping or scratches.
[0047] In step (5) above, the custom tooling is made of polyimide material with a surface finish of R0.3.
[0048] In step (6) above, the high-frequency induction heater has a heating power of 5kW and a resonant frequency of 500kHz.
[0049] The filling tube in step (8) above is obtained by secondary processing of Schott 8436 high aluminosilicate glass, with an outer diameter of 3mm, an inner diameter of 2mm, and a length of 30-40mm;
[0050] In step (9) above, the airtightness of the shell is tested using a helium mass spectrometer leak detector. The minimum detectable leak rate of the helium mass spectrometer leak detector is 5×10⁻⁶. -13 Pa·m 3 / s;
[0051] In step (10) above, the ultrasonic cleaner operates at a frequency of ≤40kHz to avoid cracking the housing due to excessive frequency.
[0052] Based on the aforementioned preparation method, a cylindrical sapphire atomic gas chamber shell comprises a stacked structure consisting of a first sapphire wafer, a first glass transition ring, a sapphire tube, a second glass transition ring, and a second sapphire wafer. The first sapphire wafer has a through-hole, which is fused to a filling tube. The sapphire tube, the first sapphire wafer, and the second sapphire wafer are made of α-Al₂O₃ single crystal; the first and second glass transition rings are made of DM308 electronic glass; and the filling tube is made of Schott 8436 glass. The overall leakage rate is better than 1×10⁻⁶. –12 Pa·m 3 / s.
[0053] The cylindrical sapphire atomic gas chamber shell of this invention has advantages such as low thermal expansion coefficient, low helium leakage rate, resistance to alkali corrosion, high temperature resistance, and high light transmittance, giving it significant advantages and broad application prospects in the field of quantum instruments. By using a high-frequency induction heater for non-contact heating of the gas chamber shell, the sealing problem of the sapphire material shell is solved, achieving a high-airtightness sealing.
[0054] The above description is only one specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the protection scope of the present invention.
[0055] The contents not described in detail in this specification are common knowledge to those skilled in the art.
Claims
1. A method for preparing a cylindrical sapphire atomic gas chamber shell, characterized in that... Includes the following steps: (1) Cut the first sapphire wafer and the second sapphire wafer to serve as the light-transmitting surface of the atomic gas chamber, and drill holes in the first sapphire wafer; (2) Cut the sapphire tube to serve as the main body of the atomic gas chamber; (3) Cut the first glass transition ring for the transition between the sapphire tube and the first sapphire wafer, and cut the second glass transition ring for the transition between the sapphire tube and the second sapphire wafer. (4) Grinding, polishing and shaping of the first sapphire wafer, the second sapphire wafer, the sapphire tube and the first glass transition ring and the second glass transition ring; (5) Limit the air chamber shell, and stack it in the following order: first sapphire disc - second glass transition ring - sapphire tube - second glass transition ring - second sapphire disc, and apply prestress. (6) Non-contact heating of the air chamber shell; (7) After cooling to room temperature, check the regularity of the air chamber shell, and discard the air chamber shells that have not been welded or have been deformed too much. The air chamber shells that have qualified regularity can proceed to the next step. (8) Use a flame to fuse the hole in the first sapphire wafer with the filling tube; (9) Connect the filling tube to the vacuum system and check the air tightness. If the vacuum leakage rate meets the preset requirements, remove the air chamber shell with qualified air tightness, clean the inner and outer walls of the air chamber shell, and dry it. (10) Check the light transmittance of the light-transmitting surface of the air chamber shell. If the light transmittance meets the preset requirements, check the regularity of the air chamber shell. If the regularity meets the preset requirements, the air chamber shell is qualified. If at least one of the air tightness, light transmittance, or regularity does not meet the requirements, the air chamber shell is unqualified and the unqualified air chamber shell is rejected.
2. The method for preparing a cylindrical sapphire atomic gas chamber shell according to claim 1, characterized in that, The diameter of the hole drilled in the first sapphire wafer is 1.5–2.5 mm; The outer diameter of the filling tube is 2.5–3.5 mm, the inner diameter is 1.5–2.5 mm, and the length is 30–40 mm.
3. The method for preparing a cylindrical sapphire atomic gas chamber shell according to claim 1, characterized in that, In step (3), the first glass transition ring and the second glass transition ring are both made of DM308 electronic material, and the thickness of the first glass transition ring and the second glass transition ring is 0.3 to 0.6 mm.
4. The method for preparing a cylindrical sapphire atomic gas chamber shell according to claim 1, characterized in that, Step (4) involves grinding, polishing, and shaping the first sapphire wafer, the second sapphire wafer, the sapphire tube, the first glass transition ring, and the second glass transition ring. The surface accuracy of the bonding surface is required to be better than λ / 4, the surface roughness is ≤10nm, and the light transmittance of the light-transmitting area of the first sapphire wafer and the second sapphire wafer is ≥85%@0.15~7.5μm.
5. The method for preparing a cylindrical sapphire atomic gas chamber shell according to claim 1, characterized in that, In step (5), a custom tooling made of polyimide is used to limit the gas chamber shell, and the prestress value is 0.12 to 0.15 MPa.
6. The method for preparing a cylindrical sapphire atomic gas chamber shell according to claim 1, characterized in that, Step (6) involves non-contact heating of the air chamber shell using a high-frequency induction heater. The target heating temperature is 720–750°C, and the heating time is 6–8 minutes.
7. The method for preparing a cylindrical sapphire atomic gas chamber shell according to claim 1, characterized in that, In step (9), the air tightness of the gas chamber shell is tested using a helium mass spectrometer leak detector.
8. The method for preparing a cylindrical sapphire atomic gas chamber shell according to claim 1, characterized in that, Step (9) involves cleaning the inner and outer walls of the air chamber housing using an ultrasonic cleaner with a working frequency of ≤40kHz.
9. A cylindrical sapphire atomic gas chamber shell based on the preparation method of claim 1, characterized in that, The structure comprises a stacked structure consisting of a first sapphire wafer, a first glass transition ring, a sapphire tube, a second glass transition ring, and a second sapphire wafer. The first sapphire wafer has a through hole, which is fused to the filling tube.
10. A cylindrical sapphire atomic gas chamber shell according to claim 9, characterized in that, The sapphire tube, the first sapphire wafer, and the second sapphire wafer are made of α-Al2O3 single crystal, the first glass transition ring and the second glass transition ring are made of DM308 electronic glass, and the filling tube is made of Schott 8436 glass.