A water vapor production device in a low vacuum range and a pressure measurement method

Abstract

The application relates to the technical field of vacuum pressure measurement, in particular to a water vapor preparation device in a low vacuum range and a pressure measurement method. The device comprises a water vapor sample chamber, a metal container, a measurement cavity, a first capacitive diaphragm gauge, a second capacitive diaphragm gauge and a vacuum pump set, wherein: the water vapor sample chamber is connected with the measurement cavity through a first high vacuum angle valve; the metal container is arranged in the water vapor sample chamber; the first capacitive diaphragm gauge is a low-pressure capacitive diaphragm gauge and is connected with the measurement cavity through a second high vacuum angle valve; the second capacitive diaphragm gauge is a high-pressure capacitive diaphragm gauge and is connected with the measurement cavity through a third high vacuum angle valve; and the vacuum pump set is connected with the measurement cavity through a fourth high vacuum angle valve. The application adopts a low-temperature freezing deionized water sublimation vaporization mode to obtain high-purity water vapor, can effectively remove impurity gas introduced in the process of placing the metal container, and reduces the water vapor phase change probability caused by temperature and pressure fluctuations.

Description

Technical Field

[0001] This application relates to the field of vacuum pressure measurement technology, and more specifically, to a steam preparation device and pressure measurement method in a low vacuum range. Background Technology

[0002] In fields such as semiconductors, lithography machines, and aerospace, water vapor is a major pollutant that affects the safe operation of equipment and the control of product quality. Stable and precise water vapor pressure needs to be obtained in a vacuum system.

[0003] In missions exploring the permanently shadowed region of the lunar south pole and the water ice resources at the bottom of craters, it is necessary to use a lunar soil water molecule analyzer to accurately measure the water content. Generally, water vapor corresponding to different saturated vapor pressures is obtained by water bath method and controlling external temperature, or by immersing the sample device in distilled water and then allowing the water vapor to evaporate to obtain water vapor at room temperature saturation. However, both of these methods tend to remove all liquid water when using a vacuum pump to remove impurity gases, and the obtained water vapor pressure is highly dependent on temperature.

[0004] Meanwhile, water vapor easily undergoes phase transitions under different temperature and pressure conditions. When introduced into a vacuum system, it readily condenses and is adsorbed. The amount of adsorption is related to factors such as the properties of the surface materials of the chamber and its auxiliary pipes, the surface treatment method, and temperature. Existing adsorption models cannot accurately describe the relationship between water vapor pressure and adsorption amount. Therefore, it is difficult to obtain high-purity, stable-pressure water vapor within a low vacuum pressure range using existing methods. How to obtain water vapor under precise and stable pressure within a low vacuum pressure range has become an urgent problem to be solved. Summary of the Invention

[0005] This application provides a water vapor preparation device and pressure measurement method in a low vacuum range, which obtains high-purity water vapor by freezing solid deionized water at low temperature, removing impurity gases, and then sublimating and vaporizing it.

[0006] To achieve the above objectives, this application provides a water vapor preparation device in a low vacuum range, comprising a water vapor sample chamber, a metal container, a measuring chamber, a first capacitor film gauge, a second capacitor film gauge, and a vacuum pump assembly, wherein: the water vapor sample chamber is connected to the measuring chamber via a first high-vacuum angle valve; the metal container is disposed inside the water vapor sample chamber; the first capacitor film gauge is a low-voltage capacitor film gauge, connected to the measuring chamber via a second high-vacuum angle valve; the second capacitor film gauge is a high-voltage capacitor film gauge, connected to the measuring chamber via a third high-vacuum angle valve; and the vacuum pump assembly is connected to the measuring chamber via a fourth high-vacuum angle valve.

[0007] Furthermore, the metal container is filled with cryogenically frozen deionized water.

[0008] Furthermore, the water vapor sample chamber has a spherical or cylindrical structure.

[0009] Furthermore, the measuring cavity has a spherical structure.

[0010] Furthermore, the first capacitor film gauge is a capacitor film gauge with a full scale of 13 Pa; the second capacitor film gauge is a capacitor film gauge with a full scale of 133322 Pa.

[0011] Furthermore, the relative measurement uncertainties of the first and second capacitor film gauges are both <0.4%.

[0012] Furthermore, the background leakage and outgassing rates of both the water vapor sample chamber and the measurement chamber are ≤1×10⁻⁶. -11 Pa·m 3 / s.

[0013] Furthermore, the effective pumping speed of the vacuum pump unit is >10L / s.

[0014] In addition, this application also provides a method for pressure measurement using a water vapor preparation device in a low vacuum range, comprising the following steps:

[0015] Step 1: Close the first high vacuum angle valve, open the third and fourth high vacuum angle valves, and start the vacuum pump group to evacuate the measuring chamber;

[0016] Step 2: When the pressure of the measuring chamber shown by the second capacitance diaphragm gauge is <13Pa, open the second high vacuum angle valve. When the pressure of the measuring chamber shown by the first capacitance diaphragm gauge is 0.000Pa, close the second and fourth high vacuum angle valves and stop evacuating the measuring chamber.

[0017] Step 3: Place the metal container in liquid nitrogen to cool. After the liquid nitrogen stops boiling, use tweezers to remove it. Pour deionized water into the metal container. After it is completely frozen, place the metal container containing the deionized water that has been frozen into a solid state in the water vapor sample chamber.

[0018] Step 4: Open the first high vacuum angle valve, wait for the impurity gas introduced during the placement of the metal container to expand and enter the measuring chamber, then open the fourth high vacuum angle valve and use the vacuum pump set to remove the impurity gas introduced during the placement of the metal container.

[0019] Step 5: When the pressure of the measuring chamber shown by the second capacitor diaphragm gauge is <13Pa, open the second high vacuum angle valve. When the pressure of the measuring chamber shown by the first capacitor diaphragm gauge is 0.000Pa, close the fourth high vacuum angle valve and stop using the vacuum pump group to evacuate the measuring chamber.

[0020] Step 6: Use the first capacitor membrane gauge to record the pressure change curve p(t) of the measuring chamber over time. When the first capacitor membrane gauge shows that the pressure of the measuring chamber is 13 Pa, close the second high vacuum angle valve and use the second capacitor membrane gauge to record the pressure change curve p(t) of the measuring chamber over time thereafter.

[0021] Step 7: After the water vapor in the measuring chamber reaches saturation, open the fourth high vacuum angle valve and use the vacuum pump set to evacuate the measuring chamber. When the second capacitor diaphragm gauge shows that the pressure in the measuring chamber is <13Pa, open the second high vacuum angle valve and use the first capacitor diaphragm gauge to measure the water vapor pressure in the measuring chamber.

[0022] Step 8: When the pressure of the measuring chamber displayed by the first capacitance diaphragm gauge is 0.1 Pa, close the fourth high vacuum angle valve and stop using the vacuum pump group to evacuate the measuring chamber. After that, the water vapor molecules adsorbed on the walls of the measuring chamber and its auxiliary pipes will continuously desorb, causing the pressure value displayed by the first capacitance diaphragm gauge to continuously rise.

[0023] Step 9: When the pressure in the measuring chamber is 13 Pa as indicated by the first capacitance diaphragm gauge, close the second high vacuum angle valve and use the second capacitance diaphragm gauge to record the pressure change curve p(t) of the measuring chamber over time.

[0024] Step 10: After the measurement time reaches 9000s, repeat steps 7-9 and test five times to obtain the curve of pressure change in the measurement chamber over time and the fitting function.

[0025] The steam generation apparatus and pressure measurement method in the low vacuum range provided in this application have the following advantages:

[0026] This application uses low-temperature freezing and deionized water sublimation vaporization to obtain high-purity water vapor, which can effectively remove impurity gases introduced during the placement of metal containers and reduce the probability of water vapor phase change caused by temperature and pressure fluctuations. Furthermore, by repeatedly evacuating the air, water vapor in a low vacuum pressure range is obtained, reducing the water vapor adsorbed on the walls of the chamber and auxiliary pipes. This allows the gaseous water vapor in the measuring chamber to maintain a relative equilibrium with the water vapor adsorbed on the walls of the chamber and auxiliary pipes, making it easier to obtain water vapor under different pressures. Attached Figure Description

[0027] The accompanying drawings, which form part of this application, are used to provide a further understanding of the application and to make other features, objects, and advantages of the application more apparent. The illustrative embodiments and descriptions of this application are used to explain the application and do not constitute an undue limitation of the application. In the drawings:

[0028] Figure 1 This is a schematic diagram of a water vapor preparation apparatus in a low vacuum range provided according to an embodiment of this application;

[0029] Figure 2 It is a graph showing the change of pressure inside the measuring chamber over time during pressure measurement using the embodiments of this application;

[0030] Figure 3 This is a graph showing the fitting function of the pressure inside the measurement chamber and the time during the pressure measurement process using the embodiments of this application;

[0031] In the figure: 1-Water vapor sample chamber, 2-Metal container, 3-First high vacuum angle valve, 4-First capacitance film gauge, 5-Second high vacuum angle valve, 6-Measuring chamber, 7-Third high vacuum angle valve, 8-Second capacitance film gauge, 9-Fourth high vacuum angle valve, 10-Vacuum pump set. Detailed Implementation

[0032] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0033] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0034] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0035] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0036] In addition, the term "multiple" should mean two or more.

[0037] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0038] like Figure 1 As shown, this application provides a water vapor preparation device in a low vacuum range, including a water vapor sample chamber 1, a metal container 2, a measuring chamber 6, a first capacitor film gauge 4, a second capacitor film gauge 8, and a vacuum pump assembly 10, wherein: the water vapor sample chamber 1 is connected to the measuring chamber 6 through a first high vacuum angle valve 3; the metal container 2 is disposed inside the water vapor sample chamber 1; the first capacitor film gauge 4 is a low-voltage capacitor film gauge, which is connected to the measuring chamber 6 through a second high vacuum angle valve 5; the second capacitor film gauge 8 is a high-voltage capacitor film gauge, which is connected to the measuring chamber 6 through a third high vacuum angle valve 7; and the vacuum pump assembly 10 is connected to the measuring chamber 6 through a fourth high vacuum angle valve 9.

[0039] Specifically, the water vapor preparation device in the low vacuum range provided in this application embodiment obtains high-purity and stable water vapor by sublimation and vaporization of solid deionized water after low-temperature freezing and removal of impurity gases. Through repeated evacuation, the gas adsorbed on the walls of the water vapor sample chamber 1, the measuring chamber 6, and the auxiliary pipes will gradually desorb, and the pressure rise rate will slow down with each evacuation, thereby obtaining water vapor in the low vacuum pressure range. This effectively solves the problems of easy removal of liquid water, contamination of water vapor by impurity gases, and unstable water vapor pressure during the removal of impurity gases. The water vapor sample chamber 1 is used to hold a metal container 2 containing deionized water as the source of water vapor preparation; the measuring chamber 6 is used for the preparation, testing, and storage of water vapor; the first capacitor film gauge 4 and the second capacitor film gauge 8 are used to detect the pressure inside the measuring chamber 6; the vacuum pump group 10 preferably consists of a mechanical pump and a turbomolecular pump, used to remove impurities and obtain a high vacuum background; the high vacuum angle valve is mainly used to control the opening and closing of the pipes between various instruments and the measuring chamber 6.

[0040] Furthermore, the metal container 2 is filled with cryogenically frozen deionized water. The cryogenically frozen deionized water is used as a raw material for steam preparation. During preparation, the metal container 2 is placed in liquid nitrogen for cooling. After the liquid nitrogen stops boiling, it is taken out and deionized water is injected into the metal container 2. After a period of time, it is completely frozen. The metal container 2 containing cryogenically frozen deionized water is then placed in the steam sample chamber 1. Subsequently, high-purity and stable steam is obtained by sublimation and vaporization of the cryogenically frozen deionized water.

[0041] Furthermore, the water vapor sample chamber 1 has a spherical or cylindrical structure. The water vapor sample chamber 1 is mainly used to place the metal container 2, and it is preferably spherical or cylindrical in shape.

[0042] Furthermore, the measuring cavity 6 has a spherical structure. The preferred spherical structure of the measuring cavity 6 results in a small wall thickness and surface area, uniform force distribution, and facilitates pressure testing.

[0043] Furthermore, the first capacitor film gauge 4 is a capacitor film gauge with a full scale of 13 Pa; the second capacitor film gauge 8 is a capacitor film gauge with a full scale of 133322 Pa.

[0044] Furthermore, the relative measurement uncertainty of the first capacitor film gauge 4 and the second capacitor film gauge 8 is both <0.4%.

[0045] Specifically, the full scale of the first capacitor film gauge 4 is 13 Pa, and its measurement accuracy is high within the pressure range of 1-13 Pa; the full scale of the second capacitor film gauge is 133322 Pa, and its measurement accuracy is high within the pressure range of 1000-133322 Pa; the relative measurement uncertainty of both the first capacitor film gauge 4 and the second capacitor film gauge 8 is <0.4%, which indicates high sensitivity and more accurate measurement.

[0046] Furthermore, the background leakage rate and outgassing rate of both the water vapor sample chamber 1 and the measurement chamber 6 are ≤1×10⁻⁶. -11 Pa·m 3 / s. During leak detection, the minimum leak rate of the helium mass spectrometer leak detector used reached 1×10⁻⁶. -13 Pa·m 3 / s.

[0047] Furthermore, the effective pumping speed of the vacuum pump unit 10 is >10L / s, ensuring that impurity gases are completely removed in a short time.

[0048] Furthermore, this application also provides a method for pressure measurement using a water vapor preparation device in a low vacuum range. By repeatedly evacuating the air, water vapor in a low vacuum pressure range is obtained, reducing the water vapor adsorbed on the walls of the chamber and auxiliary pipes. This allows the gaseous water vapor in the measuring chamber 6 to maintain a relative equilibrium with the water vapor adsorbed on the walls of the chamber and auxiliary pipes, enabling the acquisition of water vapor at different pressures. Specifically, the method includes the following steps:

[0049] Step 1: Close the first high vacuum angle valve 3, open the third high vacuum angle valve 7 and the fourth high vacuum angle valve 9, and start the vacuum pump group 10 to evacuate the measuring chamber 6;

[0050] Step 2: When the pressure of the measuring chamber 6 is <13Pa as indicated by the second capacitor diaphragm gauge 8, open the second high vacuum angle valve 5. When the pressure of the measuring chamber 6 is 0.000Pa as indicated by the first capacitor diaphragm gauge 4, close the second high vacuum angle valve 5 and the fourth high vacuum angle valve 9 to stop evacuating the measuring chamber 6.

[0051] Step 3: Place the metal container 2 in liquid nitrogen to cool. After the liquid nitrogen stops boiling, use tweezers to remove it. Pour deionized water into the metal container 2. After it is completely frozen for a period of time, place the metal container 2 containing the deionized water that has been frozen into a solid state at low temperature in the water vapor sample chamber 1.

[0052] Step 4: Open the first high vacuum angle valve 3, wait for the impurity gas introduced during the placement of the metal container 2 to expand and enter the measuring chamber 6, then open the fourth high vacuum angle valve 9 and use the vacuum pump set 10 to remove the impurity gas introduced during the placement of the metal container 2.

[0053] Step 5: When the pressure of the measuring chamber 6 is <13Pa as indicated by the second capacitor diaphragm gauge 8, open the second high vacuum angle valve 5. When the pressure of the measuring chamber 6 is 0.000Pa as indicated by the first capacitor diaphragm gauge 4, close the fourth high vacuum angle valve 9 and stop evacuating the measuring chamber 6 using the vacuum pump group 10.

[0054] Step 6: Use the first capacitor film gauge 4 to record the pressure change curve p(t) of the measuring chamber 6 over time. When the first capacitor film gauge 4 shows that the pressure of the measuring chamber 6 is 13 Pa, close the second high vacuum angle valve 5 and use the second capacitor film gauge 8 to record the pressure change curve p(t) of the measuring chamber 6 over time thereafter.

[0055] Step 7: After a sufficiently long time, when the water vapor in the measuring chamber 6 reaches saturation, open the fourth high vacuum angle valve 9 and use the vacuum pump group 10 to evacuate the measuring chamber 6. When the second capacitor diaphragm gauge 8 shows that the pressure in the measuring chamber 6 is <13Pa, open the second high vacuum angle valve 5 and use the first capacitor diaphragm gauge 4 to measure the water vapor pressure in the measuring chamber 6.

[0056] Step 8: When the pressure of the measuring chamber 6 displayed by the first capacitor film gauge 4 is 0.1 Pa, close the fourth high vacuum angle valve 9 and stop the vacuum pump group 10 from pumping air into the measuring chamber 6. After that, the water vapor molecules adsorbed on the measuring chamber 6 and its auxiliary pipe wall will continuously desorb, causing the pressure value displayed by the first capacitor film gauge 4 to continuously rise.

[0057] Step 9: When the pressure of the measuring chamber 6 is 13 Pa as displayed by the first capacitor film gauge 4, close the second high vacuum angle valve 5 and use the second capacitor film gauge 8 to record the pressure change curve p(t) of the measuring chamber 6 over time.

[0058] Step 10: After the measurement time reaches 9000s, repeat steps 7-9, and repeat the test five times to obtain the pressure change curve of measuring chamber 6 over time, as shown in the figure. Figure 2 As shown, and the fitting function, as follows Figure 3 As shown.

[0059] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A steam preparation apparatus in a low vacuum range, characterized in that, It includes a water vapor sample chamber, a metal container, a measuring chamber, a first capacitance thin-film gauge, a second capacitance thin-film gauge, and a vacuum pump assembly, wherein: The water vapor sample chamber is connected to the measurement chamber via a first high-vacuum angle valve; The metal container is disposed inside the water vapor sample chamber; The first capacitor film gauge is a low-voltage capacitor film gauge, which is connected to the measuring chamber through a second high-vacuum angle valve; The second capacitor film gauge is a high-voltage capacitor film gauge, which is connected to the measuring chamber through a third high-vacuum angle valve; The vacuum pump assembly is connected to the measuring chamber via a fourth high-vacuum angle valve; The metal container is filled with cryogenic deionized water.

2. The steam preparation apparatus in the low vacuum range according to claim 1, characterized in that, The water vapor sample chamber has a spherical or cylindrical structure.

3. The steam preparation apparatus in the low vacuum range according to claim 2, characterized in that, The measuring cavity has a spherical structure.

4. The steam preparation apparatus in the low vacuum range according to claim 3, characterized in that, The first capacitor film gauge is a capacitor film gauge with a full scale of 13 Pa; the second capacitor film gauge is a capacitor film gauge with a full scale of 133322 Pa.

5. The steam preparation apparatus in the low vacuum range according to claim 4, characterized in that, The relative measurement uncertainty of both the first capacitor film gauge and the second capacitor film gauge is <0.4%.

6. The steam preparation apparatus in the low vacuum range according to claim 5, characterized in that, The background leakage rate and outgassing rate of both the water vapor sample chamber and the measurement chamber are ≤1×10⁻⁶. -11 Pa·m 3 / s.

7. The steam preparation apparatus in the low vacuum range according to claim 6, characterized in that, The effective pumping speed of the vacuum pump set is >10 L / s.

8. A method for pressure measurement using the water vapor preparation apparatus in the low vacuum range as described in claim 7, characterized in that, Includes the following steps: Step 1: Close the first high vacuum angle valve, open the third and fourth high vacuum angle valves, and start the vacuum pump group to evacuate the measuring chamber; Step 2: When the pressure of the measuring chamber shown by the second capacitance diaphragm gauge is <13Pa, open the second high vacuum angle valve. When the pressure of the measuring chamber shown by the first capacitance diaphragm gauge is 0.000Pa, close the second and fourth high vacuum angle valves and stop evacuating the measuring chamber. Step 3: Place the metal container in liquid nitrogen to cool. After the liquid nitrogen stops boiling, use tweezers to remove it. Pour deionized water into the metal container. After it is completely frozen, place the metal container containing the deionized water that has been frozen into a solid state in the water vapor sample chamber. Step 4: Open the first high vacuum angle valve, wait for the impurity gas introduced during the placement of the metal container to expand and enter the measuring chamber, then open the fourth high vacuum angle valve and use the vacuum pump set to remove the impurity gas introduced during the placement of the metal container. Step 5: When the pressure of the measuring chamber shown by the second capacitor diaphragm gauge is <13Pa, open the second high vacuum angle valve. When the pressure of the measuring chamber shown by the first capacitor diaphragm gauge is 0.000Pa, close the fourth high vacuum angle valve and stop using the vacuum pump group to evacuate the measuring chamber. Step 6: Use the first capacitor membrane gauge to record the pressure change curve p(t) of the measuring chamber over time. When the first capacitor membrane gauge shows that the pressure of the measuring chamber is 13 Pa, close the second high vacuum angle valve and use the second capacitor membrane gauge to record the pressure change curve p(t) of the measuring chamber over time thereafter. Step 7: After the water vapor in the measuring chamber reaches saturation, open the fourth high vacuum angle valve and use the vacuum pump set to evacuate the measuring chamber. When the second capacitor diaphragm gauge shows that the pressure in the measuring chamber is <13Pa, open the second high vacuum angle valve and use the first capacitor diaphragm gauge to measure the water vapor pressure in the measuring chamber. Step 8: When the pressure of the measuring chamber displayed by the first capacitance diaphragm gauge is 0.1 Pa, close the fourth high vacuum angle valve and stop using the vacuum pump group to evacuate the measuring chamber. After that, the water vapor molecules adsorbed on the walls of the measuring chamber and its auxiliary pipes will continuously desorb, causing the pressure value displayed by the first capacitance diaphragm gauge to continuously rise. Step 9: When the pressure in the measuring chamber is 13 Pa as indicated by the first capacitance diaphragm gauge, close the second high vacuum angle valve and use the second capacitance diaphragm gauge to record the pressure change curve p(t) of the measuring chamber over time. Step 10: After the measurement time reaches 9000s, repeat steps 7-9 and test five times to obtain the curve of pressure change in the measurement chamber over time and the fitting function.

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