A high vacuum degree measuring device based on press membrane damping effect

Abstract

The application provides a high-vacuum measuring device based on a squeeze-film damping effect, and belongs to the technical field of vacuum pressure measurement. The upper and lower ends of a pendulum plate are respectively connected to one end of a low-loss flexible support structure. The two low-loss flexible support structures are used to suppress the pendulum effect of the pendulum plate, and only the rotational movement of the pendulum plate around the low-loss flexible support structure is reserved. An air-wall device is located in the vibration direction of the pendulum plate and has a preset interval with the pendulum plate, and is used to increase the squeeze-film damping when the pendulum plate vibrates. A vibration starting device is used to apply a driving force to the pendulum plate, so that the pendulum plate swings. The damping effect of residual gas in the environment to be measured makes the vibration of the pendulum plate gradually attenuate. An angle detector is used to obtain the amplitude attenuation factor of the pendulum plate vibration, and the total pressure of the environment to be measured is obtained by combining the pressure and damping relationship. The application can realize the measurement of extremely high vacuum.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of vacuum pressure measurement, and more particularly, to a high vacuum degree measuring device based on a pressure film damping effect. BACKGROUND

[0002] In the measurement process, most vacuum gauges first cause a physical phenomenon in the measured gas through a certain method, then measure the physical quantity related to the gas pressure in this process, and then indirectly measure the pressure of the measured gas. For example, thermal conductivity vacuum gauges, ionization vacuum gauges, and magnetic suspension rotor vacuum gauges.

[0003] Thermal conductivity vacuum gauges, such as Pirani gauges and thermocouple gauges, are based on the principle that the number of gas molecules affects the thermal conductivity. The vacuum degree is estimated by measuring the heat loss of the heating element. In a vacuum environment, the reduction of gas molecules will slow down the heat transfer, so the gas pressure is determined by the change in temperature or the current required to maintain the temperature of the heating element. However, their accuracy is greatly affected by the type of gas, and the heat generated will change the pressure of the gas, so they are usually only suitable for low vacuum to medium vacuum measurement, and are not suitable for high vacuum or accurate measurement of specific gas mixtures. Ionization vacuum gauges are usually used to measure high vacuum to ultra-high vacuum. They estimate the vacuum degree by measuring the ions produced by the collision of electrons with gas molecules. Under the action of an electric field, the emitted electrons ionize the gas molecules to produce an ion current, and the size of the current is proportional to the vacuum degree. However, the vacuum gauge will produce electrons and ions during the measurement process, thereby changing the composition of the gas and causing interference to the test environment, and even damaging the measurement equipment.

[0004] Magnetic suspension rotor vacuum gauges are commonly used for medium vacuum to high vacuum measurement, and as a damping type viscous vacuum gauge, they do not have the shortcomings of the above-mentioned vacuum gauges. It uses the relative decay rate of the rotor speed proportional to the gas pressure to measure the vacuum degree. The rotor is composed of small metal balls and placed in a metal tube. It is magnetically suspended by external permanent magnets and three pairs of electromagnetic coils, and the position of the rotor is adjusted and driven to rotate by the electromagnetic coils. After the drive is disconnected, the rotor speed continuously decreases under the action of gas molecular damping, and the vacuum degree can be reflected by measuring the decay rate of the rotor speed. The vacuum gauge does not produce electrons, ions and heat in the test environment, and does not change the composition and pressure of the gas during measurement, so it does not interfere with the test environment. However, the small gas damping effect on the rotor of the vacuum gauge leads to low sensitivity, and its manufacturing difficulty is high, and the cost is expensive, so how to measure the dilute gas with high precision and measure the vacuum degree without interfering with the test environment is still a problem to be solved. SUMMARY

[0005] In view of the defects of the prior art, the purpose of the present application is to provide a high vacuum degree measuring device based on the compression film damping effect, aiming at solving the problems of poor measurement accuracy of the existing vacuum gauge in the rare gas pressure and the interference of the existing vacuum gauge measurement on the test environment.

[0006] To achieve the above-mentioned purpose, the present application provides a high vacuum degree measuring device based on the compression film damping effect, comprising: a vacuum connecting section, a measuring cavity, a pendulum plate, a low-loss flexible support structure, a gas wall device, a vibration starting device and an angle detector.

[0007] The measuring cavity is communicated with the gas to be measured through the vacuum connecting section; the upper and lower ends of the pendulum plate are respectively connected with one end of a low-loss flexible support structure; the other end of the two low-loss flexible support structures is respectively fixed with the upper and lower inner walls of the measuring cavity, for suppressing the pendulum effect of the pendulum plate and only retaining the rotational movement of the pendulum plate around the low-loss flexible support structure; the gas wall device is vertically fixed in the measuring cavity and located in the direction of the pendulum plate vibration, and a predetermined distance is reserved between the pendulum plate and the gas wall device, for increasing the compression film damping when the pendulum plate vibrates; the vibration starting device is installed on the inner wall of the measuring cavity, for applying a driving force to the pendulum plate to make the pendulum plate swing, and the damping effect of the residual gas in the environment to be measured makes the vibration of the pendulum plate gradually attenuate; the angle detector is used to obtain the amplitude attenuation factor of the pendulum plate vibration, and the total pressure of the environment to be measured is obtained by combining the pressure and damping relationship.

[0008] Further preferably, the angle detector comprises: a laser emitter, a light transmission hole, a reflecting mirror, a light spot position detector and a data processing module.

[0009] The reflecting mirror is installed on the inner wall of the measuring cavity in front of the pendulum plate, and there is one light transmission hole on the wall of the measuring cavity on both sides of the reflecting mirror; the laser emitter and the light spot position detector are respectively fixed on the outer wall of the measuring cavity at the light transmission hole; the data processing module is connected with the light spot position detector through a cable.

[0010] The laser emitter is used to provide laser; the laser is reflected between the reflecting mirror and the pendulum plate for multiple times; the light spot position detector is used to detect the displacement of the outgoing light spot; the data processing module is used to obtain the amplitude attenuation factor of the pendulum plate vibration according to the displacement of the outgoing light spot, and the total pressure of the environment to be measured is obtained by combining the pressure and damping relationship.

[0011] Further preferably, the gas wall device is located behind the pendulum plate, and the relative scale of the opposite area formed by the gas wall device is greater than the predetermined distance.

[0012] It should be pointed out here that the relative scale of the opposite area formed by the gas wall device and the pendulum plate is much larger than the distance in practice, and the predetermined distance between the pendulum plate and the gas wall device can be adjusted according to the measurement requirements to increase the compression film damping when the pendulum plate vibrates.

[0013] Further preferably, the vibration starting device is located behind the pendulum plate.

[0014] Further preferably, the cross section shape of the oscillation direction of the pendulum is rectangular, and the center of the long side of the two sides is symmetrically connected with a low-loss flexible support structure.

[0015] Further preferably, the cross section shape of the oscillation direction of the pendulum is axisymmetric figure.

[0016] Further preferably, the cross section shape of the oscillation direction of the pendulum is rectangular, T-shaped or circular.

[0017] Further preferably, the laser emitter is a semiconductor laser.

[0018] Further preferably, the side of the pendulum opposite to the mirror is coated with a high-reflectivity optical coating.

[0019] Compared with the prior art, the above technical solutions conceived by the present application have the following beneficial effects in general:

[0020] The high-vacuum measuring device based on the squeeze film damping effect provided by the present application does not need to apply high voltage inside, and can avoid the interference of electrostatic effect and charged particles; the low-loss flexible torsion pendulum structure is used to directly detect the viscous damping of residual gas, and the vibration state of the pendulum is measured by an optical method, so that the detection is not affected by the gas components and does not generate thermal interference to the test environment; at the same time, a small gap is constructed near the pendulum to form a gas film, and the mechanical effect of the rare gas is amplified by the squeeze film damping effect, so that the measurement of extremely high vacuum can be realized.

[0021] The high-vacuum measuring device based on the squeeze film damping effect provided by the present application, the pendulum is vibrated by the vibration starting device, and the damping effect of the residual gas in the environment to be measured will gradually attenuate the vibration of the pendulum, the vibration condition of the pendulum can be measured by a non-contact angle detector, the amplitude attenuation factor of the pendulum can be obtained by processing the angle data, and finally the total pressure of the environment to be measured is obtained by combining the pressure-damping correlation theory and the calibration parameters; wherein the non-contact angle detection can be realized by the method of multiple reflections of laser on the pendulum and the mirror, and finally the displacement of the light spot is detected, which can amplify the pendulum vibration signal and reduce the demand for light spot position detector, thereby having extremely high sensitivity. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a top view cross-sectional structure schematic diagram of the squeeze film damping vacuum gauge provided by the embodiment of the present application;

[0023] Figure 2 is a front view cross-sectional structure schematic diagram of the squeeze film damping vacuum gauge provided by the embodiment of the present application;

[0024] BRIEF DESCRIPTION OF DRAWINGS:

[0025] 1-vacuum connecting section; 2-measuring cavity; 3-pendulum; 4-low-loss flexible support structure; 5-gas-wall device; 6-vibration starting device; 7-angle detector; 8-laser emitter; 9-light hole; 10-mirror; 11-light spot position detector. DETAILED DESCRIPTION

[0026] For the convenience of understanding, the English abbreviations and related technical terms involved in the embodiments of the present application are explained and described below.

[0027] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

[0028] The present application provides a high vacuum degree measuring device based on the pressure film damping effect. The pressure film damping coefficient and the absolute pressure of the gas are related, and the measurement of the gas pressure, especially the rarefied gas, can be realized. The pendulum vibrating in the rarefied gas will be collided by the gas molecules, especially in a narrow space. Due to the pressure film damping effect, the collision effect of the gas molecules will increase, thereby causing the gradual attenuation of the pendulum vibration amplitude. At this time, the change of the amplitude can be directly detected by using the angle detector, and the damping generated by the gas effect can be measured, thereby realizing the measurement of the current gas pressure. Compared with the magnetic suspension rotor vacuum gauge, the pressure film damping effect will significantly increase the damping of the mechanical movement, and the main mechanical structure is adopted to avoid the electromagnetic interference caused by power supply, so that the accurate measurement of the rarefied gas pressure is more easily realized.

[0029] As shown in Figure 1 and Figure 2 , the present application provides a high vacuum degree measuring device based on the pressure film damping effect, which comprises a vacuum connecting section 1, a measuring cavity 2, a pendulum 3, a low-loss flexible support structure 4, a gas-wall device 5, a vibration starting device 6 and an angle detector 7.

[0030] The measuring cavity 2 is communicated with the gas to be measured through the vacuum connecting section 1. The upper and lower center of the pendulum 3 is respectively symmetrically connected with one end of a low-loss flexible support structure 4, and the other end of the two low-loss flexible support structures 4 is respectively fixed with the upper and lower inner walls of the measuring cavity 2, so as to suppress the pendulum effect of the pendulum 3, and only the rotational movement of the pendulum 3 around the low-loss flexible support structure 4 is reserved. The gas-wall device 5 is vertically fixed in the measuring cavity 2, located behind the pendulum 3 and opposite to the rear end of the pendulum 3, and a small gap is reserved between the two to increase the pressure film damping when the pendulum 3 vibrates. The vibration starting device 6 is fixedly installed on the inner wall of the measuring cavity 2 and located at the side and rear of the pendulum 3, and can apply a driving force to the pendulum 3 to make the pendulum 3 vibrate.

[0031] The angle detector 7 comprises a laser emitter 8, a light hole 9, a mirror 10, a light spot position detector 11 and a data processing module; the mirror 10 is fixedly installed on the inner wall of the measuring cavity 2 in front of the pendulum plate 3 and faces the front end of the pendulum plate 3, and there is one light hole 9 on the wall of the measuring cavity 2 on each side of the mirror 10; the laser emitter 8 and the light spot position detector 11 are fixedly installed on the outer wall of the measuring cavity 2 at the light hole 9, and the data processing module is connected with the light spot position detector 11 through a cable.

[0032] The membrane damping vacuum gauge provided by the embodiment of the application has simple structure, does not need to apply high voltage inside, can avoid the interference of electrostatic effect and charged particles, directly detects the viscous damping of residual gas by using a low-loss flexible torsional pendulum structure, realizes direct measurement of pressure, forms a gas film by constructing a small gap near the pendulum plate 3 at the same time, amplifies the mechanical effect of rare gas by using the membrane damping effect, and can measure an extremely high vacuum degree. The principle of the application is as follows: the pendulum plate 3 is vibrated by the vibration starting device 6 and periodically swings, the damping effect of residual gas in the environment to be measured can make the vibration of the pendulum plate 3 gradually attenuate, the vibration condition of the pendulum plate 3 can be measured by the non-contact angle detector 7, the amplitude attenuation factor of the pendulum plate 3 can be obtained by processing the angle data, and finally the total pressure of the environment to be measured is obtained by combining the pressure-damping correlation theory and the calibration parameters; wherein the non-contact angle detection can be realized by the method that the laser is reflected on the pendulum plate 3 and the mirror 10 for multiple times and finally the displacement of the light spot is detected, the method can amplify the pendulum vibration signal and reduce the demand for the light spot position detector 11, so that the sensitivity is extremely high.

[0033] It should be understood that expressions such as "include" and "may include" used in the present application indicate the presence of disclosed functions, operations or constituent elements, and do not limit one or more additional functions, operations and constituent elements. In the present application, terms such as "include" and / or "have" can be interpreted to mean that specific features, numbers, operations, constituent elements, components or combinations thereof are present, but cannot be interpreted to exclude the presence or addition of one or more other features, numbers, operations, constituent elements, components or combinations thereof.

[0034] In the description of the embodiments of the present application, it should be noted that, unless otherwise explicitly specified and limited, the term "connection" should be understood in a broad sense, for example, "connection" can be detachable connection, or can be non-detachable connection; can be direct connection, or can be indirect connection through an intermediate medium.

[0035] In addition, in the embodiments of the present application, the mathematical concepts of symmetry, equality, parallel, perpendicular, etc. are mentioned. These limitations are for the current process level, not the absolute strict definition in the mathematical sense, and a small amount of deviation is allowed, such as approximately symmetrical, approximately equal, approximately parallel, approximately perpendicular, etc. For example, A is parallel to B, which means that A and B are parallel or approximately parallel, and the included angle between A and B can be between 0 degrees and 10 degrees. A is perpendicular to B, which means that A and B are perpendicular or approximately perpendicular, and the included angle between A and B can be between 80 degrees and 100 degrees.

[0036] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or replacements within the technical scope disclosed in the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A high vacuum degree measuring device based on the pressure film damping effect, characterized in that, include: Vacuum connection section, measuring cavity, swing plate, low-loss flexible support structure, air wall device, vibration starting device and angle detector; The measuring chamber is connected to the gas to be measured via a vacuum connection section; the upper and lower ends of the pendulum are symmetrically connected to one end of a low-loss flexible support structure; the other ends of the two low-loss flexible support structures are fixed to the upper and lower inner walls of the measuring chamber, respectively, to suppress the pendulum effect and retain only the rotational motion of the pendulum around the low-loss flexible support structure; the gas wall device is vertically fixed in the measuring chamber, located in the direction of pendulum vibration, and a preset distance is reserved between it and the pendulum to increase the pressure damping of the pendulum during vibration; the vibration initiation device is installed on the inner wall of the measuring chamber to apply a driving force to the pendulum, causing it to swing, and the damping effect of the residual gas in the measured environment causes the vibration of the pendulum to gradually decay; the angle detector is used to obtain the amplitude attenuation factor of the pendulum vibration, and combined with the pressure and damping relationship, the total pressure of the measured environment is obtained.

2. The high vacuum degree measuring device according to claim 1, characterized in that, The angle detector includes: a laser emitter, a light-transmitting aperture, a reflector, a light spot position detector, and a data processing module; A reflector is installed on the inner wall of the measuring cavity directly in front of the pendulum, and there is a light-transmitting hole on each side of the measuring cavity wall of the reflector; the laser emitter and the spot position detector are respectively fixed on the outer wall of the measuring cavity at the light-transmitting hole; the data processing module is connected to the spot position detector through a cable. The laser emitter provides the laser beam; the laser beam is reflected multiple times between the reflector and the pendulum; the spot position detector is used to detect the displacement of the emitted spot; the data processing module is used to obtain the amplitude attenuation factor of the pendulum vibration based on the displacement of the emitted spot, and combined with the pressure and damping relationship, to obtain the total pressure of the environment under test.

3. The high vacuum degree measuring device according to claim 1 or 2, characterized in that, The air wall device is located directly behind the pendulum, and the relative size of the resulting facing area is larger than the preset spacing; the preset spacing between the pendulum and the air wall device can be adjusted according to measurement requirements.

4. The high vacuum degree measuring device according to claim 1 or 2, characterized in that, The oscillation device is located behind the pendulum plate.

5. The high vacuum degree measuring device according to claim 1 or 2, characterized in that, The two low-loss flexible support structures on both sides of the pendulum are identical.

6. The high vacuum degree measuring device according to claim 1, characterized in that, The cross-sectional shape of the pendulum in the direction of vibration is an axisymmetric figure.

7. The high vacuum degree measuring device according to claim 6, characterized in that, The cross-sectional shape of the pendulum in the direction of vibration is rectangular, T-shaped, I-shaped, or circular.

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