Plasma probe array calibration method based on radiation spectrum and infrared imaging

Abstract

The present invention relates to the field of plasma probe calibration, and provides a plasma probe array calibration method based on radiation spectroscopy and infrared imaging. The surface temperature of the probe array is measured, and the plume parameters of the stably operating Hall thruster are measured using the probe array to obtain the volt-ampere characteristic curve collected by the probe array at this time. An infrared imager is then used to measure the surface temperature of the probe array to obtain the temperature difference of the probe heated by bombardment. Combined with the secondary electron emission coefficient of the probe surface, the secondary current value is calculated. Combined with the ion current value measured by the probe itself, the electron current value is corrected to obtain a true volt-ampere characteristic curve, and the accurate electron temperature density is calculated. A spectrometer is used to measure the electron temperature electron density at this time through spectroscopy, and the electron temperature electron density measured by the modified probe is compared to achieve calibration of the plasma probe array. This is used to solve the problem that the probe measurement results lack calibration and the accuracy is difficult to assess.

Description

Technical Field

[0001] The invention belongs to the technical field of aerospace plasma probe test calibration, and in particular relates to a plasma probe array calibration method based on radiation spectrum and infrared imaging. Background Art

[0002] Space plasma thrusters, represented by Hall thrusters and ion thrusters, are widely used in spacecraft attitude control, position maintenance, drag compensation, orbit transfer, and other tasks. The measurement of plasma parameters plays a very important role in thruster research.

[0003] Electrostatic probes are the oldest yet most commonly used diagnostic method for low-temperature plasmas. Their principle is to place a bare metal wire with a Langmuir probe tip into the plasma. By applying a bias voltage to the probe, information such as the electron temperature and density within the plasma is measured. Commonly used probes include planar probes, cylindrical probes, dual probes, and emission probes. For engineering tasks such as measuring thruster plume boundaries, multiple or diverse probes are often combined into a plasma probe array to obtain plasma parameters in multiple directions and more detailed information about plasma sub-parameters.

[0004] Currently, the Langmuir probe can measure the most plasma parameters, and its advantages are obvious, including its simple structure, ease of use, and high spatial resolution. However, the probe method also has certain limitations. As a contact measurement method, the probe needs to enter the plasma region to perform the measurement. Therefore, the probe size, probe circuit resistance, plasma oscillations, ion current, and probe surface contamination can interfere with the probe's measurement results, making the results relatively inaccurate. Currently, the probe measurement results lack calibration, making it difficult to assess accuracy, which limits the application of this method in measuring plasma density. Summary of the Invention

[0005] The present invention provides a plasma probe array calibration method based on radiation spectrum and infrared imaging, which is used to solve the problem that probe measurement results lack calibration and accuracy is difficult to assess.

[0006] The present invention is achieved through the following technical solutions:

[0007] A plasma probe array calibration method based on radiation spectroscopy and infrared imaging, wherein the plasma probe array 7 of the plasma probe array calibration method includes a spherical probe 1, a planar probe 4, a cylindrical probe I2, and a cylindrical probe II5; the probe array 7 is arranged on a cross-shaped bracket 3, the spherical probe 1 and the planar probe 4 are arranged at opposite ends of the cross-shaped bracket 3, the cylindrical probe I2 and the cylindrical probe II5 are arranged at opposite ends of the cross-shaped bracket 3, and the spherical probe 1, the planar probe 4, the cylindrical probe I2, and the cylindrical probe II5 are arranged at intervals;

[0008] The plasma probe array calibration method comprises the following steps:

[0009] Step 1: placing the plasma probe array 7 in a vacuum tank 55 and evacuating the vacuum tank 55;

[0010] Step 2: measuring the probe surface temperature of the plasma probe array 7 based on the vacuum tank 55 evacuated in step 1;

[0011] Step 3: Turn on the Hall thruster 33 and wait for it to operate stably, then use the probes of the plasma probe array 7 to measure the Hall thruster plume parameters at this time. The probes of the plasma probe array 7 collect the volt-ampere characteristic curve at this time;

[0012] Step 4: measuring the surface temperature after the plasma probe array 7 collects the Hall thruster plume parameters in step 3;

[0013] Step 5: Subtract the surface temperature of the plasma probe array 7 in step 2 from the surface temperature of the probes of the plasma probe array 7 in step 4 to obtain the temperature difference of the probes of the plasma probe array 7 after being bombarded and heated by the Hall thruster plume;

[0014] Step 6: Calculate the secondary current value by combining the temperature difference after being bombarded and heated by the Hall thruster plume in step 5 with the secondary electron emission coefficient of the probe surface of the plasma probe array 7;

[0015] Step 7: Combine the secondary current value from step 6 with the ion current value measured by the probe itself to correct the electron current value and obtain the true volt-ampere characteristic curve, thereby calculating the accurate electron temperature density;

[0016] Step 8: Use spectrometer 4 to measure the electron temperature and electron density, and compare them with the electron temperature and electron density measured by the modified probe in step 7, so as to calibrate the plasma probe array.

[0017] Furthermore, a Hall thruster 33 and an optical probe 6 are also installed in the vacuum tank 55 of step 1. The Hall thruster 33 is connected to the power supply 11 and the airflow module 22 respectively. A quartz window 8 is provided on the vacuum tank 55. The optical probe 6 is connected to the spectrometer 4. The infrared imager 9 measures the internal probe surface temperature through the quartz window 8 of the vacuum tank.

[0018] Furthermore, the infrared imager 9 , the quartz window 8 , the plasma probe array 7 and the Hall thruster 33 are sequentially arranged in a straight line.

[0019] Furthermore, the center of the Hall thruster 33 is in a straight line with the center of the cross bracket 3, the probes of the plasma probe array 7 are facing the Hall thruster 33, and the spherical probe 1, the planar probe 4, the cylindrical probe I2 and the cylindrical probe II5 are all distributed on the plume boundary of the Hall thruster.

[0020] Furthermore, the optical probe 6 is connected to the spectrometer 4 outside the vacuum tank through an optical fiber via a flange. The spectrometer 4 , infrared imager 9 , power supply 11 and airflow module 22 are all arranged outside the vacuum tank 55 .

[0021] Furthermore, the vacuuming in step 1 is specifically to reduce the pressure of the vacuum tank 55 to 10 -3 Below Pa.

[0022] Furthermore, the step 3 is specifically as follows: the airflow module 22 provides the working gas with an airflow flow rate to the Hall thruster 33 , and at the same time, the power supply 11 is started to provide the Hall thruster 33 with voltage and excitation current.

[0023] Furthermore, the step 6 is specifically as follows:

[0024]

[0025] Where, is the secondary current; A The exposed portion of the probe constitutes an effective area for collecting charged ions; is the secondary electron emission coefficient of the probe, e is the electron charge, k is the Boltzmann constant, is the ion mass, Surface temperature difference.

[0026] Furthermore, the step 7 is specifically as follows:

[0027]

[0028]

[0029] Where Tev is the electron temperature in eV, V is the probe voltage, Vs is the plasma space potential, and I is the probe collection current.

[0030]

[0031] Where, n e is the electron density, S is the area of ​​the plasma sheath.

[0032] Furthermore, the electron temperature and electron density measured by the spectrometer (4) are compared with the electron temperature and electron density measured by the modified probe in step 7. Specifically,

[0033]

[0034] Where, and is the electron density and temperature measured by the probe, and is the electron temperature and density measured by spectroscopy, To measure and compare the results, the deviations of the electron temperature and electron density measured by the two methods were characterized.

[0035] The beneficial effects of the present invention are:

[0036] The present invention can calibrate the plasma probe array and ensure the accuracy and traceability of the plasma probe measurement results. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a flow chart of the method of the present invention.

[0038] Figure 2 1 and 2 are cross-sectional views of three probes of the present invention, wherein (a) is a spherical probe, (b) is a cylindrical probe, and (c) is a flat probe.

[0039] Figure 3 Schematic diagram of the plasma probe array of the present invention.

[0040] Figure 4 It is a schematic diagram of the device for calibrating the ion probe array of the present invention.

[0041] Figure 5 This is a graph showing the relationship between the secondary electron emission coefficient and temperature on the probe surface of the present invention. DETAILED DESCRIPTION

[0042] In the following description, specific details such as specific system structures and technologies are provided for illustration rather than limitation to facilitate a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid obstructing the description of the present application with unnecessary details.

[0043] It will be understood that when used in this specification and the appended claims, the term "comprising" indicates the presence of described features, integers, steps, operations, elements and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0044] It should also be understood that the terms used in this specification are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in this specification and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0045] The following is attached to this application specification Figure 1-5 , clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of this application.

[0046] In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0047] A plasma probe array calibration method based on radiation spectroscopy and infrared imaging, wherein the plasma probe array 7 of the plasma probe array calibration method includes a spherical probe 1, a planar probe 4, a cylindrical probe I2, and a cylindrical probe II5; the probe array 7 is arranged on a cross-shaped bracket 3, the spherical probe 1 and the planar probe 4 are arranged at opposite ends of the cross-shaped bracket 3, the cylindrical probe I2 and the cylindrical probe II5 are arranged at opposite ends of the cross-shaped bracket 3, and the spherical probe 1, the planar probe 4, the cylindrical probe I2, and the cylindrical probe II5 are arranged at intervals;

[0048] The plasma probe array calibration method comprises the following steps:

[0049] Step 1: placing the plasma probe array 7 in a vacuum tank 55 and evacuating the vacuum tank 55;

[0050] Step 2: measuring the probe surface temperature of the plasma probe array 7 based on the vacuum tank 55 evacuated in step 1;

[0051] Step 3: Turn on the Hall thruster 33 and wait for it to operate stably, then use the probes of the plasma probe array 7 to measure the Hall thruster plume parameters at this time. The probes of the plasma probe array 7 collect the volt-ampere characteristic curve at this time;

[0052] Step 4: measuring the surface temperature after the plasma probe array 7 collects the Hall thruster plume parameters in step 3;

[0053] Step 5: Subtract the surface temperature of the plasma probe array 7 in step 2 from the surface temperature of the probes of the plasma probe array 7 in step 4 to obtain the temperature difference of the probes of the plasma probe array 7 after being bombarded and heated by the Hall thruster plume;

[0054] Step 6: Calculate the secondary current value by combining the temperature difference after being bombarded and heated by the Hall thruster plume in step 5 with the secondary electron emission coefficient of the probe surface of the plasma probe array 7;

[0055] Step 7: Combine the secondary current value from step 6 with the ion current value measured by the probe itself to correct the electron current value and obtain the true volt-ampere characteristic curve, thereby calculating the accurate electron temperature density;

[0056] Step 8: Use spectrometer 4 to measure the electron temperature and electron density, and compare them with the electron temperature and electron density measured by the modified probe in step 7, so as to calibrate the plasma probe array.

[0057] Furthermore, a Hall thruster 33 and an optical probe 6 are also installed in the vacuum tank 55 of step 1. The Hall thruster 33 is connected to the power supply 11 and the airflow module 22 respectively. A quartz window 8 is provided on the vacuum tank 55. The optical probe 6 is connected to the spectrometer 4. The infrared imager 9 measures the internal probe surface temperature through the quartz window 8 of the vacuum tank.

[0058] Furthermore, the infrared imager 9 , the quartz window 8 , the plasma probe array 7 and the Hall thruster 33 are sequentially arranged in a straight line.

[0059] Furthermore, the center of the Hall thruster 33 is in a straight line with the center of the cross bracket 3, the probes of the plasma probe array 7 are facing the Hall thruster 33, and the spherical probe 1, the planar probe 4, the cylindrical probe I2 and the cylindrical probe II5 are all distributed on the plume boundary of the Hall thruster, so that the plasma parameters of the plume in multiple directions can be obtained.

[0060] Furthermore, the optical probe 6 is connected to the spectrometer 4 outside the vacuum tank through an optical fiber via a flange. The spectrometer 4 , infrared imager 9 , power supply 11 and airflow module 22 are all arranged outside the vacuum tank 55 .

[0061] Furthermore, the vacuuming in step 1 is specifically to reduce the pressure of the vacuum tank 55 to 10 -3 Below Pa.

[0062] Furthermore, the step 3 is specifically as follows: the airflow module 22 provides the working gas with an airflow flow rate to the Hall thruster 33 , and at the same time, the power supply 11 is started to provide the Hall thruster 33 with voltage and excitation current.

[0063] Furthermore, in step 6, the temperature difference after being bombarded and heated by the Hall thruster plume in step 5 is combined with the secondary electron emission coefficient of the probe surface of the plasma probe array (7) to calculate the secondary current value, specifically,

[0064]

[0065] Where, is the secondary current; A The exposed portion of the probe constitutes an effective area for collecting charged ions; is the secondary electron emission coefficient of the probe, e is the electron charge, k is the Boltzmann constant, is the ion mass, Surface temperature difference.

[0066] Furthermore, in step 7, the secondary current value is combined with the ion current value measured by the probe itself to correct the electron current value and obtain a true volt-ampere characteristic curve, thereby calculating the accurate electron temperature density. Specifically,

[0067]

[0068]

[0069] Where Tev is the electron temperature in eV, V is the probe voltage, Vs is the plasma space potential, and I is the probe collection current.

[0070]

[0071] Where, n e is the electron density, S is the area of ​​the plasma sheath.

[0072] Furthermore, the electron temperature and electron density measured by the spectrometer (4) are compared with the electron temperature and electron density measured by the modified probe in step 7. Specifically,

[0073]

[0074] Where, and is the electron density and temperature measured by the probe, and is the electron temperature and density measured by spectroscopy, To measure and compare the results, the deviations of the electron temperature and electron density measured by the two methods were characterized.

Claims

1. A plasma probe array calibration method based on radiation spectroscopy and infrared imaging, characterized in that: The plasma probe array (7) of the plasma probe array calibration method comprises a spherical probe (1), a planar probe (4), a cylindrical probe I (2), and a cylindrical probe II (5); the plasma probe array (7) is arranged on a cross-shaped bracket (3), the spherical probe (1) and the planar probe (4) are arranged at opposite ends of the cross-shaped bracket (3), the cylindrical probe I (2) and the cylindrical probe II (5) are arranged at opposite ends of the cross-shaped bracket (3), and the spherical probe (1), the planar probe (4), the cylindrical probe I (2), and the cylindrical probe II (5) are arranged at intervals; The plasma probe array calibration method comprises the following steps: Step 1: placing the plasma probe array (7) in a vacuum tank (55), and evacuating the vacuum tank (55); Step 2: measuring the probe surface temperature of the plasma probe array (7) based on the vacuum tank (55) evacuated in step 1; Step 3: Using the plasma probe array (7) to measure the plume parameters of the stably operating Hall thruster (33), the probes of the plasma probe array (7) collect the volt-ampere characteristic curve at this time; Step 4: Measure the surface temperature after the plasma probe array (7) collects the Hall thruster plume parameters in step 3; Step 5: subtract the surface temperature of the plasma probe array (7) in step 2 from the surface temperature of the probe of the plasma probe array (7) in step 4 to obtain the temperature difference of the probe of the plasma probe array (7) after being bombarded and heated by the Hall thruster plume; Step 6: Calculate the secondary current value by combining the temperature difference after being bombarded and heated by the Hall thruster plume in step 5 with the secondary electron emission coefficient of the probe surface of the plasma probe array (7); Step 7: Combine the secondary current value from step 6 with the ion current value measured by the probe itself to correct the electron current value and obtain the true volt-ampere characteristic curve, thereby calculating the accurate electron temperature density; Step 8: Use the spectrometer (4) to measure the electron temperature and electron density, and compare it with the electron temperature and electron density measured by the modified probe in step 7 to calibrate the plasma probe array.

2. A plasma probe array calibration method based on radiation spectrum and infrared imaging according to claim 1, characterized in that: The vacuum tank (55) of step 1 is further equipped with a Hall thruster (33) and an optical probe (6), wherein the Hall thruster (33) is connected to a power supply (11) and an airflow module (22), respectively. A quartz window (8) is provided on the vacuum tank (55), and the optical probe (6) is connected to a spectrometer (4). The infrared imager (9) measures the surface temperature of the probe inside the vacuum tank through the quartz window (8) of the vacuum tank.

3. The plasma probe array calibration method based on radiation spectrum and infrared imaging according to claim 2, characterized in that: The infrared imager (9), the quartz window (8), the plasma probe array (7) and the Hall thruster (33) are sequentially arranged in a straight line.

4. The plasma probe array calibration method based on radiation spectrum and infrared imaging according to claim 2, characterized in that: The center of the Hall thruster (33) and the center of the cross-shaped bracket (3) are in a straight line, the probes of the plasma probe array (7) are facing the Hall thruster (33), and the spherical probe (1), the planar probe (4), the cylindrical probe I (2) and the cylindrical probe II (5) are all distributed on the plume boundary of the Hall thruster.

5. The plasma probe array calibration method based on radiation spectrum and infrared imaging according to claim 2, characterized in that: The optical probe (6) is connected to the spectrometer (4) outside the vacuum tank via an optical fiber through a flange. The spectrometer (4), infrared imager (9), power supply (11) and airflow module (22) are all arranged outside the vacuum tank (55).

6. The plasma probe array calibration method based on radiation spectrum and infrared imaging according to claim 1, characterized in that: The vacuuming in step 1 is specifically to reduce the pressure of the vacuum tank (55) to 10 -3 Below Pa.

7. The plasma probe array calibration method based on radiation spectrum and infrared imaging according to claim 1, characterized in that: Specifically, the step 3 comprises the following steps: the airflow module (22) provides the Hall thruster (33) with a working gas having an airflow rate, and simultaneously starts the power supply (11) to provide the Hall thruster (33) with a voltage and an excitation current.

8. The plasma probe array calibration method based on radiation spectrum and infrared imaging according to claim 1, characterized in that: The step 6 is specifically as follows: Where, is the secondary current; A The exposed portion of the probe constitutes an effective area for collecting charged ions; is the secondary electron emission coefficient of the probe, e is the electron charge, k is the Boltzmann constant, is the ion mass, Surface temperature difference.

9. The plasma probe array calibration method based on radiation spectrum and infrared imaging according to claim 8, characterized in that: The step 7 is specifically as follows: Where Tev is the electron temperature in eV, V is the probe voltage, Vs is the plasma space potential, and I is the probe collection current. Where, n e is the electron density, S is the area of ​​the plasma sheath.

10. The plasma probe array calibration method based on radiation spectrum and infrared imaging according to claim 9, characterized in that: The electron temperature and electron density measured by the spectrometer (4) are compared with the electron temperature and electron density measured by the modified probe in step 7. Specifically, Where, and is the electron density and temperature measured by the probe, and is the electron temperature and density measured by spectroscopy, To measure and compare the results, the deviations of the electron temperature and electron density measured by the two methods were characterized.

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