Directional airflow velocity testing device and method in a vacuum environment

Abstract

The application discloses a directional airflow velocity testing device and method in a vacuum environment, which comprises a thruster working condition simulation assembly, a one-way valve, a flowmeter, a vacuum chamber, an upper computer, a bellows, an aviation plug and an ionization probe. The upper computer is electrically connected with the ionization probe to receive the electric signal of the ionization probe and calculate the directional airflow velocity according to the response time difference. The bellows is fixed in the vacuum chamber, and the ionization probe is installed on the inner side of the bellows at a position corresponding to the aviation plug. The thruster working condition simulation assembly, the one-way valve, the flowmeter and the thruster are sequentially fixed in the vacuum chamber through a hose and communicate with the bellows. The thruster working condition simulation assembly is set at different working conditions, the response time difference of the ionization probe is recorded, and the directional airflow velocity is calculated according to the distance between the ionization probes and the response time difference. The device is convenient to control, simple to calculate, can effectively and accurately test the airflow velocity and realizes the rapid response of the directional airflow velocity.

Description

Technical Field

[0001] This invention relates to the field of airflow velocity testing, and in particular to a device and method for testing directional airflow velocity in a vacuum environment. Background Technology

[0002] Directed gas flow in a vacuum environment is crucial for scenarios such as molecular beam epitaxy, ion implantation, and ground testing of space propulsion vehicles. Accurately measuring the directional gas flow velocity in a vacuum environment is a core prerequisite for optimizing process parameters, validating fluid simulation models, and ensuring equipment performance. However, the changes in the physical behavior of gases in a vacuum environment lead to significant technical bottlenecks in the measurement of directional gas flow velocity.

[0003] Existing measurement methods mainly include macroscopic differential pressure methods, thermal flow sensing methods, and optical non-contact methods. Macroscopic differential pressure methods infer flow velocity by combining the pressure difference between upstream and downstream of the pipe with flow conductance theory; however, the inability to establish an effective pressure difference during measurement leads to poor accuracy. Thermal flow sensing methods use thermistors to measure the heat loss due to gas convection or changes in heating power to estimate flow velocity; however, thermistors may induce heat escape effects, causing measurement distortion. Optical non-contact methods utilize tracer particles or molecular Doppler shifts to obtain velocity field information, but tracer particles may introduce contamination and the system is costly. Furthermore, using an ionization gauge probe combined with a data acquisition and control circuit can achieve rapid diagnosis of beam atomic density; however, this research has not solved the quantitative measurement of directional airflow velocity, and the ionization gauge probe faces challenges in directional airflow environments, such as unstable emission current, decreased thermionic emission current, and inherent measurement delays, all of which affect measurement accuracy. Therefore, achieving high-precision and stable measurement of directional airflow velocity is an urgent problem to be solved. Summary of the Invention

[0004] The purpose of this invention is to overcome the above-mentioned shortcomings of the prior art and provide a device and method for testing directional airflow velocity in a vacuum environment.

[0005] The technical solution of the present invention is: a directional airflow velocity testing device in a vacuum environment, including a thruster operating condition simulation component, a one-way valve, a flow meter, a vacuum chamber, a host computer, a bellows, an aviation plug, and an ionization probe.

[0006] The thruster operating condition simulation component is configured with different components depending on the type of thruster.

[0007] The vacuum chamber is used to simulate a vacuum environment. It is hollow inside and has an air inlet at one end.

[0008] The host computer is electrically connected to the ionization probe and integrates a detection component and a display program for processing ionization probe signals. It is used to receive the electrical signals detected by the ionization probe and calculate the directional airflow velocity based on the time difference of the received electrical signals.

[0009] The corrugated pipe is fixed inside the vacuum chamber, and one end of it is connected to the outlet of the flow meter through the air inlet on the vacuum chamber via a flexible hose.

[0010] The number of aviation plugs is two, which are fixed to the outside of the bellows.

[0011] The number of ionization probes is the same as that of the aviation plug, namely the first ionization probe and the second ionization probe. They are installed on the inside of the bellows at the position corresponding to the aviation plug. The first ionization probe is closer to the air inlet of the vacuum chamber. The distance between the first ionization probe and the second ionization probe is L. The signal lines of the two ionization probes are connected to the aviation plug through flanges.

[0012] The outlet of the thruster operating condition simulation component is connected to the inlet of the one-way valve. The outlet of the one-way valve is connected to the inlet of the flow meter. The outlet of the flow meter is fixed to the inlet of the vacuum chamber through a hose. The other end of the hose is connected to the inlet of the bellows.

[0013] A further technical solution of the present invention is: when the thruster is a cold gas thruster, the thruster operating condition simulation component is a high-pressure gas pump; when the thruster is an electric thruster, the thruster operating condition simulation component is a plasma source or a molecular number epitaxial source.

[0014] A further technical solution of the present invention is: the ionization probe is a four-electrode self-stabilizing ionization probe, including a base, a cathode, a control electrode, an accelerating electrode, and a collecting electrode. The cathode is located at the center of the base, the control electrode is spirally arranged around the cathode, the accelerating electrode is spirally arranged around the control electrode, and the collecting electrode is spirally arranged around the accelerating electrode. The control electrode, accelerating electrode, and collecting electrode are concentrically arranged. The cathode is connected to a resistor, forming a negative feedback loop with the control electrode.

[0015] A further technical solution of the present invention is that the cathode, control electrode, accelerating electrode and collecting electrode are all made of fine tungsten wires wound together, the ratio of the cross-sectional area of ​​the ionization probe to that of the bellows is less than 1:1000, and multiple ionization probes are set on the central axis of the flow meter outlet.

[0016] A further technical solution of the present invention is that the number of aviation plugs and ionization probes is the same and more than two, and the directional airflow velocity in the host computer is calculated as the average value of the directional airflow velocity calculated between every two ionization probes.

[0017] Another technical solution provided by the present invention is a method for testing directional airflow velocity in a vacuum environment, comprising the following steps: Step 1: Start the thruster operating condition simulation component and simultaneously start the first and second ionization probes to work. Open the one-way valve and flow meter. According to the different operating conditions of the simulated thruster, the flow meter monitors the flow rate and causes the thruster operating condition simulation component to generate airflow jets under different operating conditions.

[0018] Step two: Under the action of the thruster operating condition simulation component, the airflow jet enters the bellows through the flow meter, and the first and second ionization probes set at different positions in the bellows detect the particle signals in sequence.

[0019] Step 3: Transmit the particle signals detected by the ionization probes to the host computer, record the response times of the first and second ionization probes respectively, and calculate the directional airflow velocity in the vacuum environment. The calculation formula is as follows: (4) in, V This indicates the velocity of directional airflow in a vacuum environment, measured in m / s. L This indicates the distance between the first and second ionization probes, in meters (m). t 1 、t 2 These represent the response times of the first and second ionization probes in detecting the particle signal, respectively, in μs; T This represents the inherent response time of the ionization probe, expressed in μs.

[0020] Another technical solution provided by the present invention is a method for testing directional airflow velocity in a vacuum environment, comprising the following steps: Step 1: Start the thruster operating condition simulation component and all ionization probes start working. Open the check valve and flow meter. According to the different operating conditions of the simulated thruster, the flow meter monitors the flow rate and causes the thruster operating condition simulation component to generate airflow jets under different operating conditions.

[0021] Step two: Under the action of the thruster operating condition simulation component, the airflow jet enters the bellows through the flow meter, and multiple ionization probes set at different positions in the bellows detect the particle signal in sequence.

[0022] Step 3: Transmit the particle signals detected by the ionization probes to the host computer, record the response times of the particle signals detected by multiple ionization probes, and calculate the directional airflow velocity in the vacuum environment. The calculation formula is as follows: (5) in, V This indicates the velocity of directional airflow in a vacuum environment, measured in m / s. L 1 、L 2... L n These represent the distances between the first and second ionization probes, the distances between the second and third ionization probes, ..., the distances between the (n+1)th and nth ionization probes, respectively, in meters. t 1 、t 2 ... t n+1 These represent the response times of the first ionization probe detecting the particle signal, the response times of the second ionization probe detecting the particle signal, ..., the response times of the (n+1)th ionization probe detecting the particle signal, respectively, in μs; T This represents the inherent response time of the ionization probe, expressed in μs.

[0023] A further technical solution of the present invention is: the response time of the ionization probe detecting the particle signal is the sum of the ion generation time and the ion flight time, and the electron ionization collision frequency is... υ i for: (1) in, n e Electron density, in cm³ -3 ; n 0 represents atomic density, in cm³. -3 ; σ i The cross-section of the ionization collision is in cm. 2 ; ν e Average electron velocity, in cm / s. Ion generation time. t i With ion flight time t f The calculation formulas are as follows: (2) in, n + Electron density, in cm³ -3 ; d The distance between the accelerating electrode and the collecting electrode is expressed in cm. a The acceleration during ion movement is expressed in cm / s². 2 , m i This refers to the ion mass, expressed in kg. U The potential difference between the accelerating and collecting electrodes is expressed in volts (V). The response time is then obtained. t for: (3).

[0024] Compared with the prior art, the present invention has the following characteristics: This invention uses an ionization probe to measure the pulse ionization signal of the thruster in real time. The time difference of the pulse ionization signal at different locations detected by multiple ionization probes is used to calculate the directional airflow velocity in the vacuum environment. This can avoid the influence of heat generated by the thruster itself and the inherent time of the ionization probe, and achieve a fast and accurate response to the directional airflow velocity.

[0025] The detailed structure of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0026] Figure 1 This is a structural diagram of the directional airflow velocity testing device in a vacuum environment according to the present invention; Figure 2 This is a cross-sectional view of the components inside the vacuum chamber; Figure 3 This is a structural diagram of an ionization probe. Detailed Implementation

[0027] Example 1, such as Figures 1-3 As shown, the directional airflow velocity testing device in a vacuum environment includes a thruster operating condition simulation component 1, a one-way valve 2, a flow meter 3, a vacuum chamber 4, a host computer 5, a bellows 6, an aviation plug 7, and an ionization probe 8.

[0028] The thruster operating condition simulation component 1 is configured with different components depending on the type of thruster. Specifically, when the thruster is a cold gas thruster, the thruster operating condition simulation component 1 is a high-pressure gas pump. Since the operation of a cold gas thruster depends on the gas pressure difference, the gas flow generated by the gas pump storing high-pressure gases such as nitrogen or helium can meet the requirements of the actual working fluid. Therefore, a high-pressure gas pump is selected when conducting directional gas flow velocity tests in a vacuum environment for cold gas thrusters. However, when the thruster 4 is an electric thruster, ordinary gas pumps cannot achieve the high-speed, directional neutral particle beam required by electric thrusters. The thruster operating condition simulation component 1 usually selects a plasma source or a molecular number epitaxy source.

[0029] The vacuum chamber 4 is used to simulate a vacuum environment. It is hollow inside and has an air inlet at one end, capable of generating a vacuum of 1.0 × 10⁻⁶. -4 A vacuum environment of Pa.

[0030] The host computer 5 integrates relevant detection components and display programs for processing signals from the ionization probe 8. It is electrically connected to the ionization probe 8 and is used to receive the electrical signals detected by the ionization probe 8 and calculate the directional airflow velocity based on the time difference of the received electrical signals.

[0031] The corrugated pipe 6 is fixed inside the vacuum chamber 4, and one end of it is connected to the air outlet of the flow meter 3 through the air inlet on the vacuum chamber 4 via a flexible hose.

[0032] There are two aviation plugs 7, which are fixed to the outside of the bellows 6.

[0033] The ionization probe 8 is a four-electrode self-stabilizing ionization probe used to detect the electrical signal of the airflow field in a vacuum environment. For example... Figure 3 As shown, the probe includes a base 81, a cathode 82, a control electrode 83, an accelerating electrode 84, and a collecting electrode 85. The cathode 82 is located at the center of the base 81. The control electrode 83 is spirally arranged around the cathode 82, the accelerating electrode 84 is spirally arranged around the control electrode 83, and the collecting electrode 85 is spirally arranged around the accelerating electrode 84. The control electrode 83, accelerating electrode 84, and collecting electrode 85 are concentrically arranged. The cathode 82, control electrode 83, accelerating electrode 84, and collecting electrode 85 are all made of fine tungsten wire with a diameter of 0.1 mm. The overall cross-sectional area of ​​the probe is approximately 0.5 mm². 2 .

[0034] A resistor (not shown in the figure) is connected to the cathode 82, forming a negative feedback loop with the control electrode. In this embodiment, the value of the negative feedback resistor is set to 47.5 kΩ. During the actual operation of the quadrupole self-stabilizing ionization probe 8, the cathode 82 is first heated to induce electron emission. At this time, the potential of the control electrode 83 relative to the cathode 82 is set to negative, effectively stabilizing the number of emitted electrons and ensuring the stability and controllability of the emission process. A stable accelerating electric field is constructed between the accelerating electrode 84 and the cathode 82, under which the emitted electrons gain acceleration energy. When electrons collide with the thruster beam during flight, a series of physical reactions occur. Under specific conditions where the gas temperature and electron energy remain constant, the number of positive ions generated during the collision is only related to the gas pressure. These generated positive ions are then precisely captured by the collecting electrode 85, thus forming the current in the collecting electrode 85.

[0035] The response time of the four-electrode self-stabilizing ionization probe 8 in detecting the airflow is approximately the sum of the ion generation time and the ion flight time, that is, the time from ion generation to capture by the collecting electrode 85. Electron ionization collision frequency. υ i for: (1) in, n e Electron density, in cm³ -3 ; n 0 represents atomic density, in cm³. -3 ; σ iThe cross-section of the ionization collision is in cm. 2 ; ν e Average electron velocity, in cm / s. Ion generation time. t i With ion flight time t f The calculation formulas are as follows: (2) in, n + Electron density, in cm³ -3 ; d The distance between the accelerating electrode 84 and the collecting electrode 85 is expressed in cm. a The acceleration during ion movement is expressed in cm / s². 2 , m i This refers to the ion mass, expressed in kg. U The potential difference between the accelerating electrode 84 and the collecting electrode 85 is expressed in volts (V). The response time is then obtained. t for: (3) The quadrupole self-stabilizing ionization probe 8 enables the system to have strong damping characteristics, effectively suppressing high-frequency jitter caused by airflow pulsation, thereby obtaining smoother measurement data.

[0036] The number of ionization probes 8 is the same as that of the aviation plug 7, namely the first ionization probe and the second ionization probe, which are installed inside the bellows 6 at positions corresponding to the aviation plug 7. The cross-sectional area of ​​the bellows 6 is approximately 500 mm². 2 The ratio of ionization probe 8 to bellows 6 is less than 1:1000, thus making the obstruction effect of ionization probe 8 on directional airflow negligible. The first ionization probe is close to the air inlet of vacuum chamber 4, and the distance between the first and second ionization probes is L. In this embodiment, L is 100 mm. The signal lines of the two ionization probes 8 are connected to the aviation plug 7 through a flange (not shown in the figure).

[0037] The outlet of the thruster operating condition simulation component 1 is connected to the inlet of the one-way valve 2. The outlet of the one-way valve 2 is connected to the inlet of the flow meter 3. The outlet of the flow meter 3 is fixed to the inlet of the vacuum chamber 5 through a hose. The other end of the hose is connected to the inlet of the bellows 6.

[0038] Example 2 is the same as Example 1 in basic content, except that: in the directional airflow velocity testing device in the vacuum environment, the number of aviation plug 7 and ionization probe 8 is the same and more than two, for example, three or four, and the directional airflow velocity in the host computer 5 is calculated as the average value of the directional airflow velocity calculated between every two ionization probes 8.

[0039] Example 3 is the same as Example 1 in basic content, except that: in the directional airflow velocity testing device in the vacuum environment, the multiple ionization probes 8 are set on the central axis of the outlet of the flow meter 3 in order to improve the collection efficiency of the ionization probes 8 and make the measured particle signal more accurate.

[0040] Example 4: A method for testing the directional airflow velocity in a vacuum environment using the aforementioned Example 1 or Example 3, comprising the following steps: Step 1: Simultaneously with the activation of the thruster operating condition simulation component 1, the first and second ionization probes 8 begin to work, and the one-way valve 2 and flow meter 3 are opened. Depending on the different operating conditions of the simulated thruster, the flow rate is monitored by the flow meter 2, causing the thruster operating condition simulation component 1 to generate airflow jets under different operating conditions.

[0041] Step 2: Under the action of the thruster operating condition simulation component 1, the airflow beam enters the bellows 6 through the flow meter 3, and the two ionization probes 8 set at different positions in the bellows 6 detect the particle signal in turn.

[0042] Step 3: Transmit the particle signal detected by ionization probe 8 to host computer 5, record the response time of the particle signal detected by the first and second ionization probes respectively, and calculate the directional airflow velocity in the vacuum environment. The calculation formula is as follows: (4) in, V This indicates the velocity of directional airflow in a vacuum environment, measured in m / s. L This indicates the distance between the first and second ionization probes, in meters (m). t 1 、t 2 These represent the response times of the first and second ionization probes in detecting the particle signal, respectively, in μs; T The inherent response time of the ionization probe is expressed in μs. As can be seen from formula (4), by using the first and second ionization probes and adopting a multi-point layout, the differential algorithm used in the calculation of directional airflow velocity eliminates the influence of the inherent response time of the ionization probe 8 itself, thereby improving the accuracy of velocity measurement.

[0043] Example 5: A method for testing directional airflow velocity in a vacuum environment using the aforementioned Example 2 or 3, comprising the following steps: Step 1: Start the thruster operating condition simulation component 1 and all ionization probes 8 start working. Open the one-way valve 2 and flow meter 3. According to the different operating conditions of the simulated thruster, the flow rate is monitored by the flow meter 2, so that the thruster operating condition simulation component 1 generates airflow jets under different operating conditions.

[0044] Step 2: Under the action of the thruster operating condition simulation component 1, the airflow jet enters the bellows 6 through the flow meter 3, and multiple ionization probes 8 set at different positions in the bellows 6 detect the particle signal in sequence.

[0045] Step 3: Transmit the particle signals detected by ionization probe 8 to the host computer 5, record the response times of the particle signals detected by multiple ionization probes, and calculate the directional airflow velocity in the vacuum environment. The calculation formula is as follows: (5) in, V This indicates the velocity of directional airflow in a vacuum environment, measured in m / s. L 1 、L 2 ... L n These represent the distances between the first and second ionization probes, the distances between the second and third ionization probes, ..., the distances between the (n+1)th and nth ionization probes, respectively, in meters. t 1 、t 2 ... t n+1 , respectively, represent the response time of the first ionization probe detecting the particle signal, the response time of the second ionization probe detecting the particle signal, ..., the response time of the (n+1)th ionization probe detecting the particle signal, in μs. It can be seen from formula (5) that, due to the use of multiple ionization probes and a multi-point layout, the differential algorithm used in calculating the directional airflow velocity eliminates the influence of the inherent response time of the ionization probe 8 itself, thus improving the accuracy of the measured velocity.

Claims

1. A device for testing directional airflow velocity in a vacuum environment, characterized by: Includes thruster operating condition simulation components, check valves, flow meters, vacuum chambers, host computers, bellows, aviation connectors, and ionization probes; The thruster operating condition simulation component is configured with different components according to different types of thrusters; The vacuum chamber is used to simulate a vacuum environment. It is hollow inside and has an air inlet at one end. The host computer is electrically connected to the ionization probe and integrates a detection component and a display program for processing ionization probe signals. It is used to receive the electrical signals detected by the ionization probe and calculate the directional airflow velocity based on the time difference of the received electrical signals. The corrugated pipe is fixed inside the vacuum chamber, and one end of it is connected to the outlet of the flow meter through the air inlet on the vacuum chamber via a flexible hose. The number of aviation plugs is two, which are fixed to the outside of the bellows; The number of ionization probes is the same as that of the aviation plug, namely the first ionization probe and the second ionization probe. They are installed inside the bellows at the position corresponding to the aviation plug. The first ionization probe is closer to the air inlet of the vacuum chamber. The distance between the first ionization probe and the second ionization probe is L. The signal lines of the two ionization probes are connected to the aviation plug through a flange. The outlet of the thruster operating condition simulation component is connected to the inlet of the one-way valve. The outlet of the one-way valve is connected to the inlet of the flow meter. The outlet of the flow meter is fixed to the inlet of the vacuum chamber through a hose. The other end of the hose is connected to the inlet of the bellows.

2. The directional airflow velocity testing device in a vacuum environment as described in claim 1, characterized in that: When the thruster is a cold gas thruster, the thruster operating condition simulation component is a high-pressure gas pump; when the thruster is an electric thruster, the thruster operating condition simulation component selects a plasma source or a molecular number epitaxial source.

3. The directional airflow velocity testing device in a vacuum environment as described in claim 1, characterized in that: The ionization probe is a four-electrode self-stabilizing ionization probe, including a base, a cathode, a control electrode, an accelerating electrode, and a collecting electrode. The cathode is located at the center of the base, the control electrode is spirally arranged around the cathode, the accelerating electrode is spirally arranged around the control electrode, and the collecting electrode is spirally arranged around the accelerating electrode. The control electrode, accelerating electrode, and collecting electrode are concentrically arranged. The cathode is connected to a resistor, forming a negative feedback loop with the control electrode.

4. The directional airflow velocity testing device in a vacuum environment as described in claim 3, characterized in that: The cathode, control electrode, accelerating electrode, and collecting electrode are all made of fine tungsten wires wound together. The ratio of the cross-sectional area of ​​the ionization probe to that of the bellows is less than 1:1000. Multiple ionization probes are set on the central axis of the flow meter outlet.

5. The directional airflow velocity testing device in a vacuum environment as described in claim 1, characterized in that: The number of aviation plugs and ionization probes is the same and more than two, and the directional airflow velocity in the host computer is calculated as the average of the directional airflow velocities calculated between every two ionization probes.

6. A method for testing directional airflow velocity in a vacuum environment according to any one of claims 1 to 4, characterized in that: Includes the following steps, Step 1: Start the thruster operating condition simulation component and simultaneously start the first and second ionization probes to work. Open the check valve and flow meter. According to the different operating conditions of the simulated thruster, the flow rate is monitored by the flow meter, so that the thruster operating condition simulation component generates airflow jets under different operating conditions. Step 2: Under the action of the thruster operating condition simulation component, the airflow jet enters the bellows through the flow meter, and the first and second ionization probes set at different positions in the bellows detect the particle signals in sequence. Step 3: Transmit the particle signals detected by the ionization probes to the host computer, record the response times of the first and second ionization probes respectively, and calculate the directional airflow velocity in the vacuum environment. The calculation formula is as follows: （4） in, V This indicates the velocity of directional airflow in a vacuum environment, measured in m / s. L This indicates the distance between the first and second ionization probes, in meters (m). t 1 、t 2 These represent the response times of the first and second ionization probes in detecting the particle signal, respectively, in μs; T This represents the inherent response time of the ionization probe, expressed in μs.

7. A method for testing directional airflow velocity in a vacuum environment according to any one of claims 1 to 5, characterized in that: Includes the following steps, Step 1: Start the thruster operating condition simulation component and all ionization probes start working. Open the check valve and flow meter. According to the different operating conditions of the simulated thruster, the flow rate is monitored by the flow meter, so that the thruster operating condition simulation component generates airflow jets under different operating conditions. Step 2: Under the action of the thruster operating condition simulation component, the airflow jet enters the bellows through the flow meter, and multiple ionization probes set at different positions in the bellows detect the particle signal in sequence. Step 3: Transmit the particle signals detected by the ionization probes to the host computer, record the response times of the particle signals detected by multiple ionization probes, and calculate the directional airflow velocity in the vacuum environment. The calculation formula is as follows: （5） in, V This indicates the velocity of directional airflow in a vacuum environment, measured in m / s. L 1 、L 2 ... L n These represent the distances between the first and second ionization probes, the distances between the second and third ionization probes, ..., the distances between the (n+1)th and nth ionization probes, respectively, in meters. t 1 、t 2 ... t n+1 These represent the response times of the first ionization probe detecting the particle signal, the response times of the second ionization probe detecting the particle signal, ..., the (n+1)th ionization probe detecting the particle signal, respectively, in μs; T This represents the inherent response time of the ionization probe, expressed in μs.

8. The method for testing directional airflow velocity in a vacuum environment as described in claim 6 or 7, characterized in that: The response time of the ionization probe to detect the particle signal is the sum of the ion generation time and the ion flight time, and the electron ionization collision frequency is... υ i for: （1） in, n e Electron density, in cm³ -3 ; n 0 represents atomic density, in cm³. -3 ; σ i The cross-section of the ionization collision is in cm. 2 ; ν e Average electron velocity, in cm / s; ion generation time t i With ion flight time t f The calculation formulas are as follows: （2） in, n + Electron density, in cm³ -3 ; d The distance between the accelerating electrode and the collecting electrode is expressed in cm. a The acceleration during ion movement is expressed in cm / s². 2 , m i This refers to the ion mass, expressed in kg. U The potential difference between the accelerating and collecting electrodes is expressed in volts (V); the response time is further obtained. t for: （3）。

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