Lithium atom furnace for spectrum experiment and preparation method thereof

Abstract

The invention belongs to the technical field of spectral measurement equipment, and provides a lithium atom furnace for a spectral experiment and a preparation method thereof.The lithium atom furnace comprises a vacuum tube body, a lithium ion battery, a lithium ion battery and a lithium ion battery, the communicating piece is arranged at the port of the vacuum tube body and used for blocking the vacuum tube body, a vacuum glass window is arranged on the communicating piece, and the vacuum glass window and the port of the vacuum tube body are located on the same axis; the heating structure comprises a heating piece and a heat preservation layer, the heating piece and the heat preservation layer are arranged on the outer wall face of the vacuum pipe body, the temperature in the vacuum pipe body is controlled through cooperation of the heating piece and the heat preservation layer, the temperature in the vacuum pipe body is gradually reduced from the center of the vacuum pipe body to the two end openings, and the end opening temperature is lower than the structural melting point of the vacuum glass window. The atomic furnace can be conveniently suitable for various spectrum experiments, the system stability in the experiment process can be effectively improved, the attachment degree of atomic steam on the vacuum glass window is reduced, the spectrum effect is enhanced, and the service life of the system is prolonged.

Description

Technical Field

[0001] The present invention belongs to the technical field of spectral measurement equipment, and particularly relates to a lithium atomic furnace for spectral experiments and a preparation method thereof. Background Art

[0002] The research objects of atomic and molecular physics experiments are often specific atoms or molecules. For metals with melting points higher than room temperature, we often use high-temperature atomic furnaces to prepare the required atomic samples, such as Group IA atoms. Among them, metallic lithium, with a melting point of 180 °C, is very suitable for using a high-temperature atomic furnace to prepare the required lithium atoms. At the same time, because lithium atoms, as the lightest and simplest-structured metal, have a relatively simple spectral structure, they are widely used in various research fields of atomic and molecular physics, including precision measurement fields, many-body physics fields, and various cross fields.

[0003] The size of traditional lithium atomic furnaces is within 50 cm. When used in spectral measurement experiments, in order to obtain a strong enough signal, the temperature of the atomic furnace needs to be maintained above 350 °C to obtain a high-density atomic vapor. Some researchers, in order to save the space occupied by experimental instruments and enhance the signal at the same time, made shorter lithium atomic furnaces and baked the temperature to 450 °C. However, in this case, additional measures need to be taken to prevent the glass window from bursting due to excessive temperature and the problem of being coated with high-density lithium vapor.

[0004] When designing an atomic furnace, it is necessary to consider that the higher the temperature, the greater the safety hazards; it is also necessary to consider that high-density atomic vapor is very likely to produce coatings on the inner wall of the atomic furnace cavity and the glass window during the diffusion process; on the one hand, the rapid evaporation of the sample under high-temperature conditions will reduce the utilization rate of the sample, and on the other hand, the high-density lithium vapor in the furnace is more likely to form a coating on the glass window, which will rapidly reduce the transmittance of the spectral laser, thus affecting the experimental results; and when the atomic furnace system works in a high-vacuum environment for a long time, the vacuum degree of the system will gradually deteriorate over time. On the one hand, it is because a certain amount of gas will be released from the inner wall of the cavity, and on the other hand, it is because there is a pressure difference of 5 to 6 orders of magnitude between the inside and outside of the cavity, and the gas in the environment will slowly enter the inside through the gaps of the cavity. When the air pressure inside the cavity is relatively large, the experiment cannot be carried out. Some researchers choose to always connect a vacuum pump to the atomic furnace and directly operate the vacuum pump to improve the vacuum degree when it deteriorates, while some other researchers choose to evacuate the atomic furnace once in a while. These methods greatly increase the complexity of the experiment.

[0005] Therefore, the present application designs a lithium atomic furnace for spectral experiments and a preparation method thereof to solve the above technical problems. Summary of the Invention

[0006] The object of the present invention is to provide a lithium atomic furnace for spectroscopic experiments and a preparation method thereof to solve the above problems, which can be conveniently applied to various spectroscopic experiments, effectively improve the system stability during the experiment, reduce the adhesion degree of atomic vapor on the vacuum glass window, enhance the spectroscopic effect, and extend the service life of the system.

[0007] To achieve the above object, the present invention provides the following solution: A lithium atomic furnace for spectroscopic experiments includes

[0008] a vacuum tube body, which stores atomic vapor inside for spectroscopic experiments;

[0009] a connecting member, which is arranged at the port of the vacuum tube body for sealing the vacuum tube body, and a vacuum glass window is arranged on the connecting member, and the vacuum glass window and the port are on the same axis;

[0010] a heating structure, including a heating element and a heat insulation layer, both of which are arranged on the outer wall surface of the vacuum tube body, and the temperature inside the vacuum tube body is controlled by the cooperation of the heating element and the heat insulation layer, and gradually decreases along the two port directions from the center of the vacuum tube body, and the temperature of the port is lower than the structural melting point of the vacuum glass window.

[0011] Preferably, it further includes

[0012] a vacuum detection unit, which is arranged on any one of the connecting members for detecting the air pressure inside the vacuum tube body;

[0013] wherein, a valve is arranged on the other connecting member far away from the vacuum detection unit, the valve is used to connect a vacuum pump, the vacuum pump is used to prepare a vacuum environment inside the vacuum tube, and the valve is a valve body structure that can be switched between open and closed;

[0014] a temperature measurement unit, which is arranged on the outer wall of the vacuum tube body for monitoring the temperature from the center to the port of the vacuum tube body;

[0015] a cage net, which is arranged inside the vacuum tube body, and the cage net is used to place a metal lithium sample and re-collect the metal lithium that flows to the edge of the vacuum tube body due to melting by capillary action.

[0016] Preferably, a bracket is fixedly connected to the vacuum tube body, and the middle part inside the vacuum tube body is the placement point of the metal lithium sample.

[0017] Preferably, the heating element includes a heating tape wound around the outer wall surface of the vacuum tube body, one end of the heating tape is connected to a power supply, the heat insulation layer is used to wrap the heating tape, and the thickness of the heat insulation layer gradually decreases from the middle part of the vacuum tube body to both ends.

[0018] Preferably, the connecting member includes a three-way pipe fixedly connected to the port of the vacuum tube body, and a vacuum glass window is fixedly connected to one side opposite to the port of the three-way pipe.

[0019] Preferably, the temperature measuring unit is fixedly connected to the outer wall surface of the vacuum tube body.

[0020] Preferably, the vacuum detection unit includes a vacuum gauge disposed on the three-way pipe. The vacuum gauge is fixedly connected to one end of the three-way pipe far from the vacuum tube body and the vacuum glass window, and the vacuum gauge is used for electrical connection with a vacuum gauge.

[0021] A method for preparing a lithium atomic furnace, characterized in that, based on the lithium atomic furnace for spectral experiments according to claim 1, the method includes the following steps:

[0022] Structure installation: Clean the lithium atomic furnace with acetone, install the system as shown, and replace the vacuum glass window with a blind plate. The outer thermal insulation layer of the vacuum tube body is uniformly coated with heat-insulating material;

[0023] Structure degassing: Connect a vacuum pump through a valve to evacuate the vacuum tube body. During the evacuation process, start the heating element and detect the temperature through the temperature measuring unit. Bake the temperature of the vacuum tube body to about 300 °C and keep it for two days. After turning off the heating element and the valve, lower the vacuum tube body to room temperature;

[0024] Structure breaking the vacuum: Pass an inert gas such as argon into the vacuum tube body through the valve, and use the vacuum detection unit to detect the air pressure value in the vacuum tube body to be slightly greater than the atmospheric pressure;

[0025] Sample preparation: Insert one end of the vacuum tube body into the vacuum glove box to communicate with the vacuum glove box, ensure that there is no obvious air leakage at the connection, fill the vacuum glove box with an inert gas such as argon until the internal air pressure is slightly greater than the atmospheric pressure. Place metallic lithium at the center inside the vacuum tube body through a cage net in the vacuum glove box, and then seal the vacuum tube body through the connecting member. Then repeat the structure degassing, noting that the oil on the surface of the metallic lithium needs to be cleaned, and the metallic lithium is cut into particles with a diameter not exceeding 2 mm;

[0026] Sample degassing: Replace the blind plate with a vacuum glass window. During the operation, always align the argon gas nozzle with the disassembled port of the vacuum tube body to ensure that only argon gas flows through the vacuum tube body during the subsequent operation; Bake the system again. During the process, the highest temperature measured by the temperature measuring unit near the glass window does not exceed 250 °C. Maintain the operation of the vacuum pump for 2 days and then lower the central baking temperature to about 180 °C, and continue to maintain the operation of the vacuum pump for about 5 days; Turn off the mechanical pump and the valve and lower the vacuum tube body to room temperature;

[0027] The system is on standby. The tin foil paper uniformly coated outside the vacuum tube is replaced with a coating method in which the number of layers gradually decreases from the middle to both ends along the vacuum tube body. By adjusting the heat dissipation distribution, the temperature gradually decreases along the direction from the center to the port of the vacuum tube body. During use, the air pressure inside the vacuum tube is detected by the vacuum detection unit. When it is less than 0.1 Pa, the lithium atom furnace is started for spectral experiments. When the air pressure is not less than 0.1 Pa, only the temperature at the center of the vacuum tube body needs to be baked to about 300 °C and maintained for 1 day, then the vacuum degree can rise. When the temperature is reduced to 200 °C, it can be directly used for spectral experiments.

[0028] Compared with the prior art, the present invention has the following advantages and technical effects:

[0029] 1. The present invention uses the vacuum tube body for spectral experiments. Not only does the atomic vapor generated during the lithium atom experiment gradually decrease the temperature inside the vacuum tube body from the center to the port under the combined action of the heating element and the heat preservation layer, making the density of the atomic vapor gradually decrease from the center to the port, effectively slowing down the plating speed caused by the atomic vapor adhering to the vacuum glass window, and enabling the efficiency of light entering the spectral experiment area from the vacuum glass window to be maintained at a relatively high level for a long time. On the one hand, the relatively high light utilization rate and the relatively long interaction interval between light and atomic vapor provide favorable conditions for enhancing the spectral experiment signal under low-temperature conditions. On the other hand, the temperature of the vacuum glass window is close to room temperature, eliminating the need for additional cooling measures, which not only reduces the maintenance difficulty of the equipment, extends the service life of the equipment, but also improves the safety of the experiment.

[0030] 2. Since the vacuum degree deteriorates after the lithium atom furnace has been placed for a period of time, the impurity gas (mainly nitrogen) leaking into the vacuum tube body is prone to chemical reaction with lithium atoms, generating stable chemical crystals (such as Li3N) attached to the inner wall of the atomic furnace. The present invention continuously bakes the lithium atom furnace through the heating element. When the temperature at the center of the lithium atom furnace is raised above the melting point of lithium, enough lithium atom vapor is generated to react with nitrogen, converting gaseous nitrogen into solid Li3N crystals, thereby improving the vacuum degree. Therefore, as long as a sufficient amount of lithium sample is placed in the furnace, after the atomic furnace is prepared, there is no need for additional vacuum equipment, and the vacuum inside the furnace can be re-adjusted to the range required for spectral experiments by baking, thus greatly improving the convenience during the use of the lithium atom furnace. Description of the Drawings

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings:

[0032] Figure 1 Schematic structural diagram of a lithium atomic furnace;

[0033] Figure 2 Flow chart of the preparation method of the lithium atomic furnace;

[0034] Figure 3 Schematic diagram of thermocouple temperature detection;

[0035] Among them, 1. Vacuum glass window; 2. Three-way pipe; 3. Valve; 4. Vacuum tube body; 5. Cage net; 6. Heating tape; 7. Lithium metal sample; 8. Vacuum gauge tube; 9. Support; 10. Temperature measurement unit; 11. Thermal insulation layer. Specific implementation manners

[0036] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0037] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0038] Embodiment: Refer to Figure 1 、 Figure 3 , a lithium atomic furnace for spectroscopic experiments, including,

[0039] A vacuum tube body 4, which stores atomic vapor inside for spectroscopic experiments;

[0040] A connecting member 2, which is arranged at the port of the vacuum tube body 4 for sealing the vacuum tube body 4. A vacuum glass window 1 is arranged on the connecting member 2, and the vacuum glass window 1 and the port are on the same axis;

[0041] A heating structure, including a heating element 6 and a thermal insulation layer 11. The heating element 6 and the thermal insulation layer 11 are both arranged on the outer wall surface of the vacuum tube body 4. The temperature inside the vacuum tube body 4 is adjusted by the cooperation of the heating element 6 and the thermal insulation layer 11, so that it gradually decreases from the center of the vacuum tube body 4 along the port direction, and the temperature of the port is lower than the structural melting point of the vacuum glass window 1.

[0042] The present invention uses the vacuum tube body 4 to store atomic vapor for spectroscopic experiments. The vacuum tube body 4 is sealed by arranging connecting members 2 at both ends of the vacuum tube body 4, and a vacuum glass window 1 coaxial with the port of the vacuum tube body 4 is arranged on the connecting member 2. When spectroscopic experiments are carried out inside the vacuum tube body 4, due to the cooperation of the heating element 6 and the thermal insulation layer 11, the temperature inside the vacuum tube body 4 gradually decreases along the axis from the center to both sides of the vacuum glass window 1;

[0043] On the one hand, the vacuum tube body 4 is relatively long (the length in this embodiment is 80 cm). The temperature is maintained at a relatively high level by the heating element 6 and the heat insulation layer 11. The metal lithium sample is placed in the center. During the experiment, the density of lithium atom vapor at the center position is the highest, and it gradually decreases from the center of the vacuum tube body 4 towards both sides in the direction of the vacuum glass window 1. Thus, the density of lithium atom vapor near the vacuum glass window 1 is effectively reduced, and the speed of the coating generated by the attachment of atomic vapor on the vacuum glass window 1 is delayed. Therefore, the light transmittance of the glass window 1 can be maintained at a relatively high level, and further, the efficiency of light entering the spectral experiment area from the vacuum glass window 1 can be maintained at a relatively high level for a long time;

[0044] On the other hand, the sufficiently long vacuum tube body 4 also ensures that light and atomic vapor have a sufficiently long interaction interval, providing favorable conditions for obtaining a sufficiently strong spectral experiment signal under relatively low temperature conditions. And as the temperature gradually decreases from the center of the vacuum tube body 4 along the port direction, the temperature of the vacuum glass window 1 approaches room temperature, eliminating the need for additional cooling measures. This not only reduces the maintenance difficulty of the equipment, prolongs the service life of the equipment, but also improves the safety of the experiment.

[0045] In addition, when the lithium atom furnace has been placed for some time and the vacuum degree deteriorates, the impurity gas leaking into the vacuum tube body 4 is mainly nitrogen. Since nitrogen easily reacts with lithium atoms to form stable Li3N solid, when the central temperature of the lithium atom furnace is raised above the melting point of lithium, enough lithium vapor can be generated to chemically react with nitrogen to form a solid, thereby improving the vacuum degree. Therefore, as long as a sufficient amount of lithium sample is placed in the furnace, after the atomic furnace is prepared, it is not necessary to use additional vacuum equipment to re-prepare the vacuum in the furnace to the range required for spectral experiments, thus greatly improving the convenience during the use of the lithium atom furnace.

[0046] Furthermore, it further includes,

[0047] A vacuum detection unit, which is arranged on any one of the connecting components and is used to detect the air pressure inside the vacuum tube body 4;

[0048] Among them, a valve 3 is arranged on the other connecting component far away from the vacuum detection unit. The valve 3 is used to connect to a vacuum pump, and the vacuum pump is used to prepare the vacuum environment inside the vacuum tube body 4. The valve 3 is a valve body structure that can be switched between open and closed;

[0049] A temperature measurement unit, which is arranged on the outer wall of the vacuum tube body 4 and is used to monitor the temperature from the center to the port of the vacuum tube body 4;

[0050] A cage net 5, which is arranged inside the vacuum tube body 4. The center of the cage net 5 is used to place the metal lithium sample 7, and it uses capillary action to re-collect the molten metal lithium flowing to the edge of the vacuum tube body 4.

[0051] In this technical solution, the valve 3 is a common angle valve. Selective connection can be made between a commonly used vacuum pump in spectral experiments, a gas transmission device for introducing inert gas, etc. and the vacuum tube body 4 through the valve 3 to ensure the sealing performance inside the vacuum tube body 4 through the valve 3;

[0052] The vacuum degree inside the vacuum furnace tube during the experiment can be monitored in real time through the vacuum detection unit. The purpose of using the heating element to bake the vacuum furnace tube at a high temperature is to further promote the release of gas molecules attached to the inner wall of the vacuum furnace tube and evacuate them using the vacuum pump, thereby further improving the vacuum degree inside the vacuum tube body 4. The cage net 5 laid inside the vacuum tube body 4 is used to load the lithium metal sample 7. The lithium metal sample 7 is placed on the cage net 5 and located in the middle of the vacuum tube body 4. Through capillary action, the heated and melted lithium metal sample 7 can flow back onto the cage net 5, enhancing the utilization rate of the lithium metal sample 7. The temperature measurement unit 10 arranged inside the vacuum tube body 4 cooperates with the heating element 6 to facilitate the control of the heating temperature.

[0053] Furthermore, a support 9 is fixedly connected to the vacuum tube body 4. The middle part inside the vacuum tube body 4 is the placement point of the lithium metal sample 7. During the baking process of the entire vacuum tube body 4, the temperature at the port of the tube body 4 needs to be lower than the structural melting point of the vacuum glass window 1.

[0054] Furthermore, the heating element includes a heating tape 6 wound around the outer wall surface of the vacuum tube body 4. One end of the heating tape 6 is connected to a power source. The heat insulation layer 11 is used to wrap the heating tape 6, and the thickness of the heat insulation layer 11 gradually decreases from the middle of the vacuum tube body 4 towards both ends.

[0055] Furthermore, the connecting member includes a tee pipe 2 fixedly connected to the port of the vacuum tube body 4. One port of the tee pipe 2 is fixedly connected to the furnace tube 4, and the other port is fixedly connected with a vacuum glass window 1 and is opposite to the furnace tube 4.

[0056] In this technical solution, the length of the vacuum tube body 4 is preferably but not limited to 80 cm. The inner wall surface of the vacuum tube body 4 is provided with a cage net 5. The mesh size of the cage net 5 is preferably but not limited to 1 mm × 1 mm. A lithium metal sample 7 is placed on the cage net 5. During spectral experiments, both sides of the longer vacuum tube body 4 can effectively dissipate heat from the heating temperature. The atomic vapor of the lithium metal sample 7 will fill the entire vacuum tube body 4, and the density gradually decreases from the middle to both ends, thereby reducing the degree of atomic vapor adhering to the vacuum glass window 1. The vacuum glass window 1 is used to block the tee pipe 2. An antireflection coating of 671 nm is plated on the vacuum glass window 1 to effectively enhance the light input amount. And the tee pipe 2 is hermetically connected to the two ports of the vacuum tube body 4 through flanges. The tee pipe 2 is blocked at the other end away from the vacuum glass window 1 and the vacuum tube body 4 respectively through the provided vacuum detection unit and the valve 3 to ensure the sealing performance of the vacuum tube body 4.

[0057] Moreover, in this technical solution, the thermal insulation layer 11 is preferably but not limited to heat insulation materials such as tinfoil and asbestos mesh. By laying the thickness of the thermal insulation layer 11 to continuously decrease from the middle to both ends of the vacuum tube body 4, the effect that the temperature in the middle of the vacuum tube body 4 is higher than that at both ends is achieved.

[0058] Furthermore, the temperature measurement unit 10 is fixedly connected to the outer wall surface of the vacuum tube body 4. The temperature measurement unit 10 includes a plurality of thermocouples, and the thermocouples are attached to the outer wall surface of the vacuum tube body 4.

[0059] In this technical solution, at least five thermocouples are provided. The five thermocouples are symmetrically distributed on the outer wall surface along the axial direction of the vacuum tube body 4 from the center to both ends, so as to effectively monitor the temperature change inside the vacuum tube body 4. Figure 3 As shown in the temperature distribution measured by the 5 thermocouples evenly distributed under different heating degrees, it can be clearly found that the temperature in the middle of the vacuum tube body is the highest and symmetrically decreases along both ends.

[0060] Furthermore, the vacuum detection unit includes a vacuum gauge 8 provided on the three-way pipe 2. The vacuum gauge 8 is connected and fixedly connected to one end of the three-way pipe 2 far from the vacuum tube body 4 and the vacuum glass window 1. The vacuum gauge 8 is used for electrical connection with a vacuum gauge.

[0061] Refer to Figure 1 、 Figure 3 , in the spectroscopic experiment, the temperature is usually 200 °C. Therefore, the vacuum tube body 4 is made of stainless steel, and a plurality of thermocouples are installed on the outer wall of the vacuum tube body 4 at equal intervals. During the heating process of the heating belt 6, the temperature change can be effectively monitored, and the temperature peak change inside the vacuum tube body 4 can be observed, that is, the temperature in the middle of the vacuum tube body 4 is high and the temperature at both ends is low, which is used to ensure the experimental effect. And the vacuum gauge 8 is connected and fixed to the three-way pipe 2 through a flange. During the spectroscopic experiment, the detection end of the vacuum gauge 8 can detect the air pressure value and display it through the connected vacuum gauge, which is convenient for the staff to judge the air pressure situation inside the vacuum tube body 4. When the vacuum degree is insufficient, only the heating belt 6 needs to be started for heating. The above usage methods of the vacuum gauge 8 and the vacuum gauge are all prior arts and will not be described in detail.

[0062] Refer to Figure 2 , a preparation method of a lithium atom furnace, based on the above lithium atom furnace for spectroscopic experiments, includes the following steps:

[0063] Structure installation, cleaning the lithium atom furnace with acetone, installing the system as shown in Figure 1 , and replacing the vacuum glass window with a blind plate. The outer thermal insulation layer of the vacuum tube body 4 is evenly coated with tinfoil, so that the system can be baked to a higher temperature;

[0064] Structural degassing: Connect a vacuum pump through a valve to evacuate the vacuum tube body 4. During the evacuation process, start the heating element and detect the temperature through the temperature measurement unit. Bake the temperature of the vacuum tube body 4 to about 300 °C and maintain it for two days. After closing the heating element and the valve, lower the vacuum tube body 4 to room temperature;

[0065] Structural air breaking: Introduce an inert gas (such as argon) into the vacuum tube body 4 through a valve, and use the vacuum detection unit to detect that the air pressure value in the vacuum tube body 4 is slightly greater than the atmospheric pressure;

[0066] Sample loading and preparation: Insert one end of the vacuum tube body 4 into the vacuum glove box to communicate with the vacuum glove box, ensure that there is no obvious air leakage at the connection, and fill the vacuum glove box with an inert gas (such as argon) until the internal air pressure is slightly greater than the atmospheric pressure. Place metallic lithium at the center of the inside of the vacuum tube body 4 through a cage net in the sealed box and then seal the vacuum tube body 4 through a connecting piece. Then repeat the structural degassing, noting that the oil on the surface of the metallic lithium needs to be cleaned, and the metallic lithium is cut into particles with a diameter not exceeding 2 mm;

[0067] Sample degassing: Replace the vacuum glass window with a blind plate. During the operation process, always align the argon gas nozzle with the port where the furnace tube is disassembled to ensure that only argon gas flows through the furnace tube during the subsequent operation process; Bake the system here. During the process, the highest temperature of the thermocouple near the glass window does not exceed 250 °C. After maintaining the operation of the vacuum pump for 2 days, lower the central baking temperature to about 180 °C and continue to maintain the operation of the vacuum pump for about 5 days; Close the mechanical pump and the valve and lower the vacuum tube body 4 to room temperature;

[0068] System standby: Replace the tin foil paper evenly coated outside the vacuum tube body 4 with a coating method that gradually reduces the number of layers from the middle to both ends along the vacuum tube body 4. Adjust the heat dissipation distribution to make the temperature gradually decrease from the center to the port direction of the vacuum tube body 4. During use, detect the air pressure in the vacuum tube body 4 through the vacuum detection unit. When it is less than 0.1 Pa, start the lithium atomic furnace for spectral experiments. When the air pressure is not less than 0.1 Pa, only need to bake the central temperature of the vacuum tube body 4 to about 300 °C and maintain it for 1 day, then the vacuum degree will rise. Lower the temperature to 200 °C and directly use it for spectral experiments.

[0069] The specific implementation steps include:

[0070] S1. Clean or wipe the entire lithium atomic furnace with acetone solution, and then assemble each part. Replace the vacuum glass windows 1 on the two three-way pipes 2 with stainless steel blind plates with flanges; At this time, the wrapping thickness of the thermal insulation layer 11 at different positions of the tube body is the same, so that the heating temperature of the heating element is consistent;

[0071] S2. Open the valve 3 and connect it to a vacuum pump. Extract the gas inside the vacuum tube body 4 through the vacuum pump to create a vacuum state. Use a thermocouple to detect the temperature and stabilize the maximum temperature at around 350 °C. Keep the vacuum pump equipment operating for 2 days under high-temperature conditions, then close the valve 3 and gradually reduce the temperature to room temperature, thus completing the degassing of the overall equipment. The vacuum pump extracts the gas in the vacuum tube body 4, reducing the air pressure inside the vacuum tube body 4. Heating can further prompt the gas molecules attached to the inner wall of the vacuum tube body 4 to be released and extracted.

[0072] S3. Break the vacuum with high-purity argon. Under the condition that the temperature of the vacuum tube body 4 drops to room temperature, disconnect the connection between the valve 3 and the vacuum pump; connect the outlet of the inert gas to the valve 3, adjust the gas outlet speed so that the gas transmission pipe is completely filled with inert gas, and then slowly open the valve 3 to fill the furnace tube with inert gas until the pressure value shown by the vacuum gauge is close to one atmosphere.

[0073] S4. Load the sample and pre-pump the vacuum. Remove the three-way pipe 2 equipped with the vacuum gauge tube 8, place the metal lithium storage tank, dust-free paper, utility knife, stainless steel forceps, an aluminum plate with a flat surface, and a beaker in a self-made glove box; utilize the hole on one side of the glove box that can just pass through the CF35 flange to extend the vacuum tube body 4 into the glove box; seal the gap between the vacuum tube body 4 and the glove box with adhesive tape; remove the blind plate on the furnace tube inside the glove box; loosen the blind plate at one end of the three-way pipe 2 until the blind plate can just continuously bite the CF flange sealing ring but will not shift; fill the glove box with high-purity argon, keep the internal argon gas pressure slightly higher than the atmospheric pressure, and observe argon gas leakage at the outer end blind plate of the vacuum tube body 4; take out the metal lithium sample 7 stored in mineral oil, place it on the surface of the dust-free tissue paper, and use forceps to pick it up and turn it over repeatedly to absorb the oil on the lithium surface; use forceps to pick up the metal lithium block without obvious oil on the surface and place it in the center of the aluminum plate, use a blade to scrape off the dark skin on the surface of the lithium block, and then cut the clean lithium block into particles with a diameter not exceeding 2 mm; use forceps to take out the cage net 5, place the metal lithium sample 7 into the cage net, arrange the particles along the axis to avoid accumulation; after placing the lithium particles, push the cage net 5 back into the furnace tube to ensure that its central position coincides with the central position of the vacuum tube body 4; cover the blind plate inside the glove box and seal the blind plates at both ends of the vacuum tube body 4 with screws; repeat the process of S2.

[0074] S5. Remove the blind plates at both ends of the vacuum tube body 4 and replace them with Figure 1The vacuum glass window 1 shown in [figure reference] always aligns the argon gas nozzle with the disassembled port of the vacuum tube body 4 during operation, ensuring that only argon gas flows through the vacuum tube body 4 during subsequent operations. Repeat the process of S2. It should be noted that during the baking process, the maximum temperature of the thermocouple closest to the vacuum glass window 8 does not exceed 250 °C. After maintaining the operation of the mechanical pump unit for 2 days, reduce the central baking temperature to about 180 °C and continue to maintain the operation of the mechanical pump unit for about 5 days. Tighten the valve 3 clockwise, turn off the vacuum pump and disconnect the connection with the valve 3 to effectively degas the lithium metal sample 7, thereby ensuring the spectral experiment effect.

[0075] Since nitrogen molecules are difficult to completely remove during the vacuum preparation process, and the extremely reactive lithium atoms are prone to chemical reactions with nitrogen molecules to form stable Li3N crystals attached to the inner wall of the vacuum tube body 4. However, because the Li3N crystals are solid, the gaseous nitrogen is converted into solid crystals, which can improve the environmental vacuum to a certain extent. As long as a sufficient amount of lithium sample is placed in the furnace, the vacuum inside the vacuum tube body 4 can be re-prepared without additional vacuum equipment, thus greatly improving the convenience during the use of the lithium atom furnace.

[0076] S6. Reduce the temperature to room temperature and change the insulation layer 11 to a state where it is thicker in the middle and thinner at both ends of the vacuum tube body 4, so that the temperature after heating the heating tape 6 gradually decreases from the middle to the port of the vacuum tube body 4. During use, when the vacuum gauge 8 detects that the air pressure in the vacuum tube body 4 is less than 0.1 Pa, the lithium atom furnace can be directly used for spectral experiments. When the air pressure is not less than 0.1 Pa, only need to control the heating tape 6 to maintain heating at 300 °C for one day and then cool down to 200 °C to reduce the air pressure, and then it can be used for spectral experiments.

[0077] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention, rather than indicating or implying 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 a limitation to the present invention.

[0078] The above-described embodiments are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention should fall within the protection scope determined by the claims of the present invention.

Claims

1. A lithium atomic furnace for spectroscopic experiments, characterized in that: including, a vacuum tube body (4) which stores atomic vapor inside for spectroscopic experiments; a connecting member disposed at the port of the vacuum tube body (4) for sealing the vacuum tube body (4), a vacuum glass window (1) is provided on the connecting member, and the vacuum glass window (1) and the port are on the same axis; a heating structure including a heating element and a heat insulation layer (11), both the heating element and the heat insulation layer (11) are provided on the outer wall surface of the vacuum tube body (4), the temperature inside the vacuum tube body is controlled by the cooperation of the heating element and the heat insulation layer (11), and gradually decreases along the two port directions from the center of the vacuum tube body (4), and the temperature of the port is lower than the structural melting point of the vacuum glass window (1).

2. The lithium atomic furnace for spectroscopic experiments according to claim 1, characterized in that: It further includes, a vacuum detection unit disposed on any one of the connecting members for detecting the air pressure inside the vacuum tube body (4); wherein, a valve (3) is provided on the other connecting member away from the vacuum detection unit, the valve (3) is used to connect a vacuum pump, the vacuum pump is used to prepare a vacuum environment inside the vacuum tube body (4), and the valve (3) is a valve body structure that can be switched between open and closed; a temperature measurement unit (10) disposed on the outer wall of the vacuum tube body (4) for monitoring the temperature from the center to the port of the vacuum tube body (4); a cage net (5) disposed inside the vacuum tube body (4), the cage net (5) is used to place a metallic lithium sample (7) and re-collect the metallic lithium that flows to the edge of the vacuum tube body (4) due to melting by capillary action.

3. The lithium atomic furnace for spectroscopic experiments according to claim 1, characterized in that: A bracket (9) is fixedly connected to the vacuum tube body (4), and the middle part inside the vacuum tube body (4) is the placement point of the metallic lithium sample (7).

4. The lithium atomic furnace for spectroscopic experiments according to claim 1, characterized in that: The heating element includes a heating tape (6) wound around the outer wall surface of the vacuum tube body (4), one end of the heating tape (6) is connected to a power source, and the heat insulation layer (11) is used to cover the heating tape (6), and the thickness of the heat insulation layer (11) gradually decreases from the middle part of the vacuum tube body (4) to both ends.

5. The lithium atomic furnace for spectral experiments according to claim 2, characterized in that: The connecting member includes a tee tube (2) fixedly connected to the port of the vacuum tube body (4), and the vacuum glass window (1) is fixedly connected to the side opposite to the port of the tee tube (2).

6. The lithium atomic furnace for spectroscopic experiments according to claim 2, characterized in that: The temperature measurement unit (10) is fixedly connected to the outer wall surface of the vacuum tube body (4).

7. The lithium atomic furnace for spectroscopic experiments according to claim 5, characterized in that: The vacuum detection unit includes a vacuum gauge tube (8) disposed on the tee tube (2), the vacuum gauge tube (8) is connected and fixed to one end of the tee tube (2) away from the vacuum tube body (4) and the vacuum glass window (1), and the vacuum gauge tube (8) is used to be electrically connected to a vacuum gauge.

8. A preparation method of a lithium atomic furnace, characterized in that, The lithium atomic furnace for spectroscopic experiments according to claim 1 includes the following steps: Structure installation: Clean the lithium atomic furnace with acetone, install the system as shown, and replace the vacuum glass window with a blind plate. The outer heat insulation layer of the vacuum tube body is a uniformly coated heat insulation material; Structural degassing: Connect a vacuum pump through a valve to evacuate the vacuum tube body. During the evacuation process, start the heating element and detect the temperature through the temperature measurement unit. Bake the temperature of the vacuum tube body to about 300 °C and maintain it for two days. After closing the heating element and the valve, lower the vacuum tube body to room temperature. Structural air-breaking: Introduce an inert gas such as argon into the vacuum tube body through a valve, and use the vacuum detection unit to detect the air pressure value in the vacuum tube body to be slightly greater than the atmospheric pressure. Sample loading and preparation: Insert one end of the vacuum tube body into the vacuum glove box to communicate with the vacuum glove box, ensure that there is no obvious air leakage at the connection, fill the vacuum glove box with an inert gas such as argon until the internal air pressure is slightly greater than the atmospheric pressure. Place lithium metal at the center of the vacuum tube body through the cage net in the vacuum glove box, and then seal the vacuum tube body through the connecting piece. Then repeat the structural degassing, noting that the oil on the surface of lithium metal needs to be cleaned, and the lithium metal is cut into particles with a diameter not exceeding 2 mm. Sample degassing: Replace the blind plate with a vacuum glass window. During the operation, always align the argon gas nozzle with the disassembled port of the vacuum tube body to ensure that only argon gas flows through the vacuum tube body during the subsequent operation. Bake the system again. During the process, the highest temperature measured by the temperature measurement unit near the glass window does not exceed 250 °C. After maintaining the operation of the vacuum pump for 2 days, lower the central baking temperature to about 180 °C, and continue to maintain the operation of the vacuum pump for about 5 days. Close the mechanical pump and the valve and lower the vacuum tube body to room temperature. System standby: Replace the tin foil paper evenly coated on the outside of the vacuum tube body with a coating method that gradually reduces the number of layers from the middle to both ends along the vacuum tube body. Adjust the heat dissipation distribution to make the temperature gradually decrease from the center to the port of the vacuum tube body. When in use, detect the air pressure in the vacuum tube body through the vacuum detection unit. When it is less than 0.1 Pa, start the lithium atomic furnace for spectroscopic experiments. When the air pressure is not less than 0.1 Pa, only need to bake the central temperature of the vacuum tube body to about 300 °C and maintain it for 1 day, and the vacuum degree will rise. Lower the temperature to 200 °C and directly use it for spectroscopic experiments.

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