High vacuum degree measuring device based on pressed film damping effect

Abstract

The invention provides a high vacuum degree measuring device based on a pressed film damping effect, and belongs to the technical field of vacuum pressure measurement. The centers of the upper end and the lower end of a pendulous reed are symmetrically connected with one end of a low-loss flexible supporting structure respectively; the two low-loss flexible supporting structures are used for restraining the simple pendulum effect of the pendulous reed, and only the rotation movement of the pendulous reed around the low-loss flexible supporting structures is reserved. The air wall device is located in the vibration direction of the pendulous reed, a preset distance is reserved between the air wall device and the pendulous reed, and the air wall device is used for increasing film pressing damping when the pendulous reed vibrates. The oscillation starting device is used for applying driving force to the pendulous reed, so that the pendulous reed swings, and the vibration of the pendulous reed is gradually attenuated due to the damping effect of residual gas in the environment to be detected; and the angle detector is used for acquiring an amplitude attenuation factor of the oscillation of the pendulous reed and acquiring the total pressure of the environment to be detected by combining the pressure and damping relationship. According to the invention, the measurement of extremely high vacuum degree can be realized.

Description

Technical Field

[0001] The present application belongs to the technical field of vacuum pressure measurement, and more specifically, relates to a high vacuum degree measurement device based on squeeze film damping effect. Background Art

[0002] During the measurement process, most vacuum gauges first induce physical phenomena in the gas being measured by certain methods, and then measure the physical quantities related to the gas pressure in this process, and then indirectly measure the pressure of the gas being measured, such as thermal conductivity vacuum gauges, ionization vacuum gauges, and magnetic levitation rotor vacuum gauges.

[0003] Thermal conductivity vacuum gauges, such as Pirani vacuum gauges and thermocouple vacuum gauges, are based on the principle that the number of gas molecules affects thermal conductivity, and estimate the vacuum degree 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 temperature change of the heating element or the change of the current required to maintain the temperature. However, their accuracy is greatly affected by the type of gas, and the heat generated will change the pressure of the gas. Therefore, they are usually only suitable for low vacuum to medium vacuum measurements, and are not suitable for accurate measurement of high vacuum or specific gas mixtures. Ionization vacuum gauges are usually used to measure high vacuum to ultra-high vacuum. It estimates the vacuum degree by measuring the ions generated by the collision of electrons and gas molecules. Under the action of the electric field, the emitted electrons ionize the gas molecules and generate an ion current, the magnitude of which is proportional to the vacuum degree. However, during the measurement process, the vacuum gauge will pass a high voltage to generate electrons and ions, thereby changing the composition of the gas, interfering with the test environment, and even damaging the measuring equipment.

[0004] The magnetically suspended rotor vacuum gauge is commonly used for the measurement of medium vacuum to high vacuum, and as a damped viscous vacuum gauge, it does not have the disadvantages of the above-mentioned vacuum gauges. It uses the relationship that the relative decay rate of the rotor speed is proportional to the gas pressure to measure the vacuum degree. Its rotor is composed of a small metal ball and placed in a metal tube. It is magnetically suspended by an external permanent magnet and three pairs of electromagnetic coils, and then the electromagnetic coils are used to adjust the rotor position and drive its rotation. After the drive is disconnected, the rotor speed continues to decrease under the damping of gas molecules, and the size of the vacuum degree can be reflected by measuring the decay rate of the speed. The vacuum gauge does not generate electrons, ions and heat in the test environment, and does not change the gas composition and pressure during measurement, so it will not interfere with the test environment. However, the gas damping effect on the rotor of the vacuum gauge is small, resulting in its low sensitivity, and it is difficult to manufacture and expensive. Therefore, how to measure rarefied gas with high precision and vacuum degree without interfering with the test environment is still a problem that needs to be solved urgently. Summary of the invention

[0005] In view of the defects of the prior art, the purpose of this application is to provide a high vacuum measurement device based on the squeeze film damping effect, aiming to solve the problem that the existing vacuum gauge has poor measurement accuracy under rarefied gas pressure and the existing vacuum gauge measurement will cause interference to the test environment.

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

[0007] The measuring cavity is connected to the gas to be measured through a vacuum connecting 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 cavity respectively, so as to suppress the single pendulum effect of the pendulum and only retain the rotational movement of the pendulum around the low-loss flexible support structure; the gas wall device is vertically fixed in the measuring cavity, located in the direction of the pendulum vibration, with a preset spacing between the pendulum and the pendulum, so as to increase the compression film damping when the pendulum vibrates; the vibration-generating device is installed on the inner wall of the measuring cavity, so as to apply a driving force to the pendulum to make it swing, and the damping effect of the residual gas in the environment to be measured 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 the total pressure of the environment to be measured is obtained by combining the relationship between pressure and damping.

[0008] Further preferably, the angle detector comprises: a laser emitter, a light hole, a reflector, a light spot position detector and a data processing module;

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

[0010] The laser transmitter is used to provide laser; the laser is reflected multiple times between the reflector and the pendulum; the light spot position detector is used to detect the displacement of the output light spot; the data processing module is used to obtain the amplitude attenuation factor of the pendulum vibration according to the displacement of the output light spot, and combine the relationship between pressure and damping to obtain the total pressure of the environment to be tested.

[0011] Further preferably, the air wall device is located directly behind the swing piece, and the relative size of the opposing area formed is larger than the preset spacing.

[0012] It should be pointed out here that the relative size of the facing area formed by the air wall device and the pendulum is much larger than the spacing in practice. The preset spacing between the pendulum and the air wall device can be adjusted according to measurement requirements to increase the compression film damping when the pendulum vibrates.

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

[0014] Further preferably, the cross-sectional shape of the pendulum in the vibration direction is a rectangle, and the centers of the long sides on both sides are symmetrically connected to a low-loss flexible support structure.

[0015] Further preferably, the cross-sectional shape of the pendulum in the vibration direction is an axisymmetric figure.

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

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

[0018] Further preferably, a surface of the swing plate facing the reflector is coated with a highly reflective optical coating.

[0019] In general, the above technical solutions conceived by this application have the following beneficial effects compared with the prior art:

[0020] The present application provides a high vacuum measurement device based on the squeezed film damping effect, which does not require high voltage to be applied inside and can avoid interference from electrostatic effects and charged particles; a low-loss flexible torsion pendulum structure is used to directly detect the viscous damping of the residual gas, and the vibration state of the pendulum is measured optically, so its detection is not affected by the gas composition and does not cause thermal interference to the test environment; at the same time, a small-pitch gap is constructed near the pendulum to form an air film, and the squeezed film damping effect is used to amplify the mechanical effect of the rarefied gas, thereby realizing the measurement of extremely high vacuum.

[0021] The present application provides a high vacuum measuring device based on the squeeze film damping effect. After being vibrated by a vibrating device, the pendulum swings periodically. The damping effect of the residual gas in the measured environment will gradually attenuate the vibration of the pendulum. The vibration of the pendulum can be measured by a non-contact angle detector. The pendulum amplitude attenuation factor can be obtained by processing the angle data. Finally, the total pressure of the measured environment can be obtained by combining the pressure-damping related theory and calibration parameters. Among them, the non-contact angle detection can be achieved by multiple reflections of the laser on the pendulum and the reflector, and finally detecting the displacement of the output light spot. This method can amplify the vibration signal of the pendulum and reduce the demand for the light spot position detector, thereby having extremely high sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0024] Description of reference numerals:

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

[0026] For ease 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 of squeeze film damping effect, which can realize the measurement of gas pressure, especially rarefied gas, by using the relationship between squeeze film damping coefficient and gas absolute pressure. The pendulum vibrating in rarefied gas will be collided by gas molecules, especially in a small space. Due to the effect of squeeze film damping, the collision effect of gas molecules will increase, resulting in the gradual attenuation of the vibration amplitude of the pendulum. At this time, the angle detector can be used to directly detect the change of amplitude and then measure the damping caused by the gas effect, thereby realizing the measurement of the current gas pressure. Compared with the magnetically levitated rotor vacuum gauge, the squeeze film damping effect will significantly increase the damping of mechanical motion, and it mainly adopts a mechanical structure to avoid electromagnetic interference caused by power-on, so it is easier to realize accurate measurement of rarefied gas pressure.

[0029] like Figure 1 and Figure 2 As shown, the embodiment of the present application provides a high vacuum degree measuring device based on squeeze film damping effect, comprising: a vacuum connection section 1, a measuring cavity 2, a pendulum 3, a low-loss flexible support structure 4, an air wall device 5, a vibration device 6 and an angle detector 7;

[0030] The measuring chamber 2 is connected to the gas to be measured through the vacuum connecting section 1; the centers of the upper and lower ends of the pendulum 3 are symmetrically connected to one end of a low-loss flexible support structure 4, and the other ends of the two low-loss flexible support structures 4 are fixed to the upper and lower inner walls of the measuring chamber 2, respectively, thereby suppressing the single pendulum effect of the pendulum 3, and only retaining the rotational movement of the pendulum 3 around the low-loss flexible support structure 4; the air wall device 5 is vertically fixed in the measuring chamber 2, located behind the pendulum 3 and directly opposite to the rear end of the pendulum 3, and a small distance is reserved between the two to increase the compression film damping when the pendulum 3 vibrates; the vibration device 6 is fixedly installed on the inner wall of the measuring chamber 2, and is located on 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 includes: a laser emitter 8, a light hole 9, a reflector 10, a spot position detector 11 and a data processing module; the reflector 10 is fixedly installed on the inner wall of the measuring cavity 2 just in front of the pendulum 3, and facing the front end of the pendulum 3, and there is a light hole 9 on each side of the reflector 10. The laser emitter 8 and the spot position detector 11 are respectively fixed on the outer wall of the measuring cavity 2 at the light hole 9, and the data processing module is connected to the spot position detector 11 through a cable.

[0032] The squeezed film damping vacuum gauge provided in the embodiment of the present application has a simple structure, and does not require high voltage to be applied inside, which can avoid interference from electrostatic effects and charged particles; a low-loss flexible torsion pendulum structure is used to directly detect the viscous damping of the residual gas, thereby realizing direct measurement of the pressure; at the same time, the present application constructs a small-pitch gap near the pendulum 3 to form an air film, and uses the squeezed film damping effect to amplify the mechanical effect of the rarefied gas, thereby realizing the measurement of extremely high vacuum degrees. The principle of the present application is as follows: the pendulum 3 swings periodically after being vibrated by the vibrating device 6, and the damping effect of the residual gas in the test environment will gradually attenuate the vibration of the pendulum 3. The vibration of the pendulum 3 can be measured by the non-contact angle detector 7, and the amplitude attenuation factor of the pendulum 3 can be obtained by processing the angle data, and finally the total pressure of the test environment can be obtained by combining the pressure-damping related theory and calibration parameters; among them, non-contact angle detection can be achieved by multiple reflections of the laser on the pendulum 3 and the reflector 10, and finally detecting the displacement of the output light spot. This method can amplify the vibration signal of the pendulum and reduce the demand for the light spot position detector 11, thereby having extremely high sensitivity.

[0033] It should be understood that expressions such as "including" and "may include" that may be used in the present application indicate the existence of the 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 "including" and / or "having" may be interpreted as indicating specific characteristics, numbers, operations, constituent elements, components, or combinations thereof, but may not be interpreted as excluding the existence or possibility of adding one or more other characteristics, 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 clearly specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium.

[0035] In addition, in the embodiments of the present application, the mathematical concepts mentioned are symmetry, equality, parallelism, verticality, etc. These limitations are all for the current state of the art, rather than being absolutely strict definitions in a mathematical sense, and allow a small amount of deviation, approximation to symmetry, approximation to equality, approximation to parallelism, approximation to verticality, etc. are all possible. For example, A and B are parallel, which means that A and B are parallel or approximately parallel, and the angle between A and B can be between 0 and 10 degrees. A and B are perpendicular, which means that A and B are perpendicular or approximately perpendicular, and the angle between A and B can be between 80 and 100 degrees.

[0036] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A high vacuum degree measuring device based on squeeze film damping effect, characterized in that: include: Vacuum connection section, measuring cavity, pendulum, low-loss flexible support structure, air wall device, vibration device and angle detector; The measuring cavity is connected to the gas to be measured through a vacuum connecting 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 cavity respectively, so as to suppress the single pendulum effect of the pendulum and only retain the rotational movement of the pendulum around the low-loss flexible support structure; the gas wall device is vertically fixed in the measuring cavity, located in the direction of the pendulum vibration, with a preset spacing between the pendulum and the pendulum, so as to increase the compression film damping when the pendulum vibrates; the vibration-generating device is installed on the inner wall of the measuring cavity, so as to apply a driving force to the pendulum to make it swing, and the damping effect of the residual gas in the environment to be measured 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 the total pressure of the environment to be measured is obtained by combining the relationship between pressure and damping.

2. The high vacuum degree measuring device according to claim 1, characterized in that: The angle detector includes: a laser emitter, a light hole, a reflector, a light spot position detector and a data processing module; The reflector is installed on the inner wall of the measuring cavity in front of the swing plate, and there is a light hole on the wall of the measuring cavity on both sides of the reflector; the laser emitter and the light spot position detector are respectively fixed on the outer wall of the measuring cavity at the light hole; the data processing module is connected to the light spot position detector through a cable; The laser transmitter is used to provide laser; the laser is reflected multiple times between the reflector and the pendulum; the light spot position detector is used to detect the displacement of the output light spot; the data processing module is used to obtain the amplitude attenuation factor of the pendulum vibration according to the displacement of the output light spot, and combine the relationship between pressure and damping to obtain the total pressure of the environment to be tested.

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 opposing area formed 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 vibration device is located behind the pendulum.

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 flap are identical.

6. The high vacuum degree measuring device according to claim 1 or 5, characterized in that: The cross-sectional shape of the pendulum piece in the vibration direction 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 piece in the vibration direction is rectangular, T-shaped, I-shaped or circular.

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