Water vapor preparation device in low vacuum range and pressure measurement method

Abstract

The invention 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 capacitance film gauge, a second capacitance film gauge and a vacuum pump set; wherein the water vapor sample chamber is connected with the measuring cavity through the first high-vacuum angle valve; the metal container is arranged in the water vapor sample chamber; the first capacitance film gauge is a low-voltage capacitance film gauge and is connected with the measuring cavity through a second high-vacuum angle valve; the second capacitance film gauge is a high-voltage capacitance film gauge and is connected with the measuring cavity through a third high-vacuum angle valve; the vacuum pump set is connected with the measuring cavity through a fourth high-vacuum angle valve. According to the method, high-purity water vapor is obtained in a low-temperature frozen deionized water sublimation vaporization mode, impurity gas introduced in the metal container placing process can be effectively pumped out, and the water vapor phase change probability caused by temperature and pressure fluctuation is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of vacuum pressure measurement, and in particular to a water vapor preparation device and a pressure measurement method within a low vacuum range. Background Art

[0002] In the fields of semiconductors, lithography machines, aerospace, etc., water vapor is the main pollutant, which is related to the safe production operation of equipment and product quality control. It is necessary to obtain stable and precise water vapor pressure in the vacuum system.

[0003] In the mission of exploring the permanent shadow area of ​​the Moon's South Pole and the water ice resources at the bottom of the crater, 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 the water bath method and controlling the external temperature, or by immersing the sample device in distilled water and then letting the water vapor evaporate to obtain the saturated water vapor at room temperature. However, these two methods are prone to completely extracting liquid water when the vacuum pump group is used to extract the impurity gas, and the obtained water vapor pressure is highly dependent on temperature.

[0004] At the same time, water vapor is prone to phase change under different temperature and pressure conditions, and is prone to condensation and adsorption after being introduced into the vacuum system. The amount of adsorption is related to the properties of the surface materials of the chamber and its associated pipelines, the surface material treatment method, temperature and other factors. The existing adsorption model is difficult to qualitatively describe the accurate relationship between water vapor pressure and adsorption. Therefore, it is difficult to obtain high-purity and stable pressure water vapor in the low vacuum pressure range using existing means. How to obtain water vapor at an accurate and stable pressure in the low vacuum pressure range has become a problem that needs to be solved urgently. Summary of the invention

[0005] The present application provides a water vapor preparation device and a pressure measurement method within a low vacuum range, which obtain high-purity water vapor by freezing solid deionized water at low temperatures, removing impurity gases, and then sublimating and vaporizing them.

[0006] In order to achieve the above-mentioned purpose, the present application provides a water vapor preparation device within a low vacuum range, including a water vapor sample chamber, a metal container, a measuring chamber, a first capacitance film gauge, a second capacitance film gauge and a vacuum pump group, wherein: the water vapor sample chamber is connected to the measuring chamber through a first high vacuum angle valve; the metal container is arranged inside the water vapor sample chamber; the first capacitance film gauge is a low-pressure capacitance film gauge, which is connected to the measuring chamber through a second high vacuum angle valve; the second capacitance film gauge is a high-pressure capacitance film gauge, which is connected to the measuring chamber through a third high vacuum angle valve; the vacuum pump group is connected to the measuring chamber through a fourth high vacuum angle valve.

[0007] Furthermore, the metal container is filled with low-temperature frozen deionized water.

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

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

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

[0011] Furthermore, the relative measurement uncertainties of the first capacitance film gauge and the second capacitance film gauge are both less than 0.4%.

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

[0013] Furthermore, the effective pumping speed of the vacuum pump group is greater than 10 L / s.

[0014] In addition, the present application also provides a method for measuring pressure 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 high vacuum angle valve and the fourth high vacuum angle valve, and start the vacuum pump group to evacuate the measuring chamber;

[0016] Step 2: When the second capacitance film gauge shows that the pressure of the measuring chamber is less than 13Pa, open the second high vacuum angle valve; when the first capacitance film gauge shows that the pressure of the measuring chamber is 0.000Pa, close the second high vacuum angle valve and the fourth high vacuum angle valve to stop pumping the measuring chamber;

[0017] Step 3: Place the metal container in liquid nitrogen to cool it down, and take it out with tweezers after the liquid nitrogen stops boiling. Pour deionized water into the metal container, and after it is completely frozen, place the metal container containing the deionized water frozen into a solid state at low temperature 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 into the measuring chamber, then open the fourth high vacuum angle valve, and use the vacuum pump group to remove the impurity gas introduced during the placement of the metal container;

[0019] Step 5: When the second capacitance film gauge shows that the pressure of the measuring chamber is less than 13Pa, open the second high vacuum angle valve; when the first capacitance film gauge shows that the pressure of the measuring chamber is 0.000Pa, close the fourth high vacuum angle valve and stop evacuating the measuring chamber with the vacuum pump group;

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

[0021] Step 7: After the water vapor in the measuring chamber reaches saturated steam, open the fourth high vacuum angle valve, and use the vacuum pump group to evacuate the measuring chamber. When the second capacitance film gauge shows that the pressure of the measuring chamber is less than 13Pa, open the second high vacuum angle valve, and use the first capacitance film gauge to measure the water vapor pressure in the measuring chamber;

[0022] Step 8: When the first capacitance film gauge displays that the pressure of the measuring chamber is 0.1Pa, 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 wall of the measuring chamber and its affiliated pipes will continue to desorb, causing the pressure value displayed by the first capacitance film gauge to continue to rise;

[0023] Step 9: When the first capacitance film gauge shows that the pressure of the measuring chamber is 13 Pa, close the second high vacuum angle valve, and use the second capacitance film gauge to record the pressure change curve p(t) of the measuring chamber over time;

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

[0025] The present application provides a water vapor preparation device and a pressure measurement method within a low vacuum range, which have the following beneficial effects:

[0026] The present application adopts the method of sublimation and vaporization of low-temperature frozen deionized water 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; and through repeated vacuuming, water vapor within a low vacuum pressure range is obtained, reducing water vapor adsorbed on the walls of the chamber and the associated pipes, so that the gas phase water vapor in the measuring chamber and the water vapor adsorbed on the walls of the chamber and the associated pipes can maintain a relatively balanced state, making it easier to obtain water vapor at different pressures. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings constituting a part of this application are used to provide a further understanding of this application, so that other features, purposes and advantages of this application become more obvious. The schematic embodiment drawings and their descriptions of this application are used to explain this application and do not constitute an improper limitation on this application. In the drawings:

[0028] Figure 1 is a schematic diagram of a water vapor preparation device within a low vacuum range provided in an embodiment of the present application;

[0029] Figure 2 is a graph showing the change of the pressure inside the measuring chamber over time during the pressure measurement process using the embodiment of the present application;

[0030] Figure 3 is a fitting function diagram of the pressure inside the measuring chamber and time during the pressure measurement process using the embodiment of the present 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 group. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work 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 and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0034] In the present application, the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings. These terms are mainly used to better describe the present application and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation.

[0035] In addition, some of the above terms may be used to express other meanings in addition to indicating orientation or positional relationship. For example, the term "on" may also be used to express a certain dependency or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in this application can be understood according to specific circumstances.

[0036] In addition, the term "plurality" shall mean two or more.

[0037] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0038] like Figure 1 As shown, the present application provides a water vapor preparation device within a low vacuum range, including a water vapor sample chamber 1, a metal container 2, a measuring chamber 6, a first capacitance film gauge 4, a second capacitance film gauge 8 and a vacuum pump group 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 arranged inside the water vapor sample chamber 1; the first capacitance film gauge 4 is a low-pressure capacitance film gauge, connected to the measuring chamber 6 through a second high vacuum angle valve 5; the second capacitance film gauge 8 is a high-pressure capacitance film gauge, connected to the measuring chamber 6 through a third high vacuum angle valve 7; the vacuum pump group 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 the embodiment of the present application obtains high-purity stable water vapor by freezing solid deionized water at low temperature, removing impurity gases, and then sublimating and vaporizing; by repeatedly pumping, the gas adsorbed on the water vapor sample chamber 1, the measuring chamber 6 and the wall of the attached pipeline will gradually desorb, and the pressure rise rate will slow down with the successive pumping, and then obtain water vapor in the low vacuum pressure range, effectively solving the problems of easy extraction of liquid water in the process of extracting impurity gases, contamination of water vapor by impurity gases, and unstable water vapor pressure. Among them, the water vapor sample chamber 1 is used to place a metal container 2 with deionized water as a source of water vapor preparation; the measuring chamber 6 is used for the preparation, testing and storage of water vapor; the first capacitance film gauge 4 and the second capacitance film gauge 8 are used to detect the pressure inside the measuring chamber 6; the vacuum pump group 10 is preferably composed of a mechanical pump and a turbomolecular pump, which is used to extract impurities and obtain a high vacuum background; the high vacuum angle valve is mainly used to control the on-off of the pipeline between each instrument and the measuring chamber 6.

[0040] Furthermore, the metal container 2 is filled with low-temperature frozen deionized water. The low-temperature frozen deionized water is used as a raw material for preparing water vapor; during preparation, the metal container 2 is placed in liquid nitrogen for cooling, and is taken out after the liquid nitrogen stops boiling, and deionized water is injected into the metal container 2. After a period of complete freezing, the metal container 2 containing the low-temperature frozen deionized water in a solid state is placed in the water vapor sample chamber 1, and subsequently, high-purity and stable water vapor is obtained by sublimation and vaporization of the low-temperature frozen deionized water;

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

[0042] Furthermore, the measuring cavity 6 is a spherical structure. The measuring cavity 6 is preferably a spherical structure, with small wall thickness and surface area, uniform force, and convenient for pressure testing.

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

[0044] Furthermore, the relative measurement uncertainties of the first capacitor film gauge 4 and the second capacitor film gauge 8 are both less than 0.4%.

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

[0046] Furthermore, the background leakage rate and degassing rate of the water vapor sample chamber 1 and the measuring chamber 6 are both ≤1×10 -11 Pa·m 3 / s. When testing for leaks, the helium mass spectrometer used has a minimum leak rate of 1×10 -13 Pa·m 3 / s.

[0047] Furthermore, the effective pumping speed of the vacuum pump group 10 is greater than 10 L / s, ensuring that the impurity gas is completely pumped out in a short time.

[0048] In addition, the embodiment of the present application also provides a method for measuring pressure using a water vapor preparation device within a low vacuum range, which obtains water vapor within a low vacuum pressure range by repeatedly pumping air, reduces water vapor adsorbed on the walls of the chamber and the attached pipes, and enables the gas phase water vapor in the measuring chamber 6 and the water vapor adsorbed on the walls of the chamber and the attached pipes to maintain a relatively balanced state, and can obtain water vapor at different pressures, which specifically 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 second capacitance film gauge 8 shows that the pressure of the measuring chamber 6 is less than 13Pa, the second high vacuum angle valve 5 is opened; when the first capacitance film gauge 4 shows that the pressure of the measuring chamber 6 is 0.000Pa, the second high vacuum angle valve 5 and the fourth high vacuum angle valve 9 are closed to stop pumping the measuring chamber 6;

[0051] Step 3: Place the metal container 2 in liquid nitrogen to cool it down, and take it out with tweezers after the liquid nitrogen stops boiling, inject deionized water into the metal container 2, and after it is completely frozen for a period of time, place the metal container 2 containing the deionized water 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 into the measuring chamber 6, then open the fourth high vacuum angle valve 9, and use the vacuum pump group 10 to remove the impurity gas introduced during the placement of the metal container 2;

[0053] Step 5: When the second capacitance film gauge 8 shows that the pressure of the measuring chamber 6 is less than 13Pa, the second high vacuum angle valve 5 is opened; when the first capacitance film gauge 4 shows that the pressure of the measuring chamber 6 is 0.000Pa, the fourth high vacuum angle valve 9 is closed, and the vacuum pump group 10 is stopped from evacuating the measuring chamber 6;

[0054] Step 6: Use the first capacitance film gauge 4 to record the pressure change curve p(t) of the measuring chamber 6 over time. When the first capacitance 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 capacitance film gauge 8 to record the pressure change curve p(t) of the measuring chamber 6 over time.

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

[0056] Step 8: When the first capacitance film gauge 4 shows that the pressure of the measuring chamber 6 is 0.1Pa, the fourth high vacuum angle valve 9 is closed, and the vacuum pump group 10 is stopped from evacuating the measuring chamber 6. After that, the water vapor molecules adsorbed on the wall of the measuring chamber 6 and its affiliated pipes will be continuously desorbed, so that the pressure value displayed by the first capacitance film gauge 4 will continue to rise;

[0057] Step 9: When the first capacitance 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 capacitance film gauge 8 to record the pressure change curve p(t) of the measuring chamber 6 over time;

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

[0059] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A water vapor preparation device in a low vacuum range, characterized in that: It includes a water vapor sample chamber, a metal container, a measuring chamber, a first capacitance film gauge, a second capacitance film gauge and a vacuum pump group, wherein: The water vapor sample chamber is connected to the measuring chamber via a first high vacuum angle valve; The metal container is arranged inside the water vapor sample chamber; The first capacitance film gauge is a low-pressure capacitance film gauge, which is connected to the measuring chamber via a second high vacuum angle valve; The second capacitance film gauge is a high-voltage capacitance film gauge, which is connected to the measuring chamber via a third high-vacuum angle valve; The vacuum pump group is connected to the measuring chamber through a fourth high vacuum angle valve.

2. The water vapor preparation device in the low vacuum range according to claim 1, characterized in that: The metal container is filled with low-temperature frozen deionized water.

3. The water vapor preparation device in the low vacuum range according to claim 2, characterized in that: The water vapor sample chamber is a spherical or cylindrical structure.

4. The water vapor preparation device in the low vacuum range according to claim 3, characterized in that: The measuring cavity is a spherical structure.

5. The water vapor preparation device in the low vacuum range according to claim 4, characterized in that: The first capacitance film gauge is a capacitance film gauge with a full scale of 1.3Pa; the second capacitance film gauge is a capacitance film gauge with a full scale of 133322Pa.

6. The water vapor preparation device in the low vacuum range according to claim 5, characterized in that: The relative measurement uncertainties of the first capacitance film gauge and the second capacitance film gauge are both less than 0.4%.

7. The water vapor preparation device in the low vacuum range according to claim 6, characterized in that: The background leakage rate and degassing rate of the water vapor sample chamber and the measuring chamber are both ≤1×10 -11 Pa·m 3 / s.

8. The water vapor preparation device in the low vacuum range according to claim 7, characterized in that: The effective pumping speed of the vacuum pump group is greater than 10 L / s.

9. A method for measuring pressure using the water vapor preparation device in a low vacuum range as claimed in claim 8, characterized in that: The steps include: Step 1: Close the first high vacuum angle valve, open the third high vacuum angle valve and the fourth high vacuum angle valve, and start the vacuum pump group to evacuate the measuring chamber; Step 2: When the second capacitance film gauge shows that the pressure of the measuring chamber is less than 13Pa, open the second high vacuum angle valve; when the first capacitance film gauge shows that the pressure of the measuring chamber is 0.000Pa, close the second high vacuum angle valve and the fourth high vacuum angle valve to stop pumping the measuring chamber; Step 3: Place the metal container in liquid nitrogen to cool it down, and take it out with tweezers after the liquid nitrogen stops boiling. Pour deionized water into the metal container, and after it is completely frozen, place the metal container containing the deionized water frozen into a solid state at low temperature 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 into the measuring chamber, then open the fourth high vacuum angle valve, and use the vacuum pump group to remove the impurity gas introduced during the placement of the metal container; Step 5: When the second capacitance film gauge shows that the pressure of the measuring chamber is less than 13Pa, open the second high vacuum angle valve; when the first capacitance film gauge shows that the pressure of the measuring chamber is 0.000Pa, close the fourth high vacuum angle valve and stop evacuating the measuring chamber with the vacuum pump group; Step 6: Use the first capacitance film gauge to record the pressure change curve p(t) of the measuring chamber over time. When the first capacitance film gauge shows that the pressure of the measuring chamber is 13 Pa, close the second high vacuum angle valve, and use the second capacitance film gauge to record the pressure change curve p(t) of the measuring chamber over time. Step 7: After the water vapor in the measuring chamber reaches saturated steam, open the fourth high vacuum angle valve, and use the vacuum pump group to evacuate the measuring chamber. When the second capacitance film gauge shows that the pressure of the measuring chamber is less than 13Pa, open the second high vacuum angle valve, and use the first capacitance film gauge to measure the water vapor pressure in the measuring chamber; Step 8: When the first capacitance film gauge displays that the pressure of the measuring chamber is 0.1Pa, 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 wall of the measuring chamber and its affiliated pipes will continue to desorb, causing the pressure value displayed by the first capacitance film gauge to continue to rise; Step 9: When the first capacitance film gauge shows that the pressure of the measuring chamber is 13 Pa, close the second high vacuum angle valve, and use the second capacitance film gauge to record the pressure change curve p(t) of the measuring chamber over time; Step 10: When the measurement time reaches 9000s, repeat steps 7-9 and repeat the test five times to obtain the curve of the change of the measurement chamber pressure over time and the fitting function.

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