Fast measurement method of plasma global average non-extended parameter of hall thruster

Abstract

This invention proposes a fast measurement method for the global average non-extensive parameter of a Hall thruster plasma. The method includes steps S1 (steady-state operation of the equipment), S2 (collecting cathode-side electron temperature, anode-side electron temperature, and discharge voltage), and S3 (calculating the global average non-extensive parameter Q). The analytical formula is: [Formula omitted for brevity]. This method abandons traditional distribution function fitting methods and directly analyzes the global average non-extensive parameter Q within the discharge channel by measuring relevant physical quantities of the anode and cathode. The analytical formula is concise and the calculation is fast, enabling on-orbit online real-time monitoring and parameter calculation. The entire process utilizes the existing temperature and pressure measurement circuits of the equipment without adding new hardware, achieving global, real-time, and low-cost measurement. It is suitable for strong non-equilibrium plasma conditions such as Hall thrusters, and the calculated non-extensive parameter can be applied to thrust modeling and operational condition monitoring.

Description

Technical Field

[0001] This invention belongs to the fields of plasma diagnostics, electric propulsion technology and non-extensive statistical applications, and specifically relates to a method for measuring the global average non-extensive parameters of a Hall thruster plasma. Background Technology

[0002] The global average non-extensive parameter Q is a core statistical indicator of non-equilibrium plasma physics in Hall thrusters. It quantitatively characterizes the degree of global deviation from thermal equilibrium and is a key parameter for high-precision modeling and analysis of electron transport and heating, sheath, oscillation, and efficiency. The global average non-extensive parameter Q in Hall thrusters is based on Tsallis non-extensive statistical mechanics and is a key statistical parameter used to quantify the degree of overall plasma deviation from the Maxwell-Boltzmann thermal equilibrium distribution within the thruster. The q-values ​​differ in different regions within the Hall thruster discharge channel (divided into the ionization region, acceleration region, and sheath). The global average non-extensive parameter Q is a spatially / temporally weighted average of the q-values ​​across the entire discharge channel, yielding a single characterizing value.

[0003] Current mainstream methods for measuring non-extensive parameters in plasma rely on techniques such as Langmuir probe acquisition of electron velocity distribution functions, multi-curve nonlinear fitting, and spectral inversion, which have the following drawbacks:

[0004] (1) The measurement process is complex, the amount of calculation is large, and it is highly dependent on high-precision diagnostic equipment;

[0005] (2) It can only achieve single-point local measurement and cannot obtain the global average non-extensive parameters of the entire discharge channel of the thruster, which is not suitable for whole machine modeling and closed-loop control of operating conditions.

[0006] (3) For the Hall thruster, which has strong non-equilibrium conditions such as dual temperature distribution, anomalous transport and electron number density reversal, the traditional fitting method has large measurement error and poor applicability.

[0007] (4) Existing non-extensive measurement methods are all based on distribution function fitting, fluctuation spectrum analysis, and multi-probe array iteration. There is no technical solution that directly calculates non-extensive parameters using the temperature difference between the anode and cathode and the discharge voltage. Summary of the Invention

[0008] The present invention aims to provide a method for measuring the global average non-extensive parameter of a Hall thruster plasma, which can quickly calculate the global average non-extensive parameter and is suitable for real-time online measurement.

[0009] Therefore, the technical solution adopted in this invention is: a fast measurement method for the global average non-extensive parameter of a Hall thruster plasma, comprising the following steps:

[0010] Step S1: Steady-state operation of the equipment;

[0011] Start the Hall thruster, adjust the working fluid flow and discharge power to the target operating conditions, and wait for the parameters to stabilize: electron temperature and discharge voltage fluctuation ≤ ±5%, and remain stable for ≥ 30s to ensure that the plasma is in a steady-state discharge state.

[0012] Step S2: Collect cathode-side electron temperature Anode side electron temperature and discharge voltage Among them, the cathode-side electron temperature Anode side electron temperature The unit is K; discharge voltage The unit is V;

[0013] Step S3: Calculate the global average non-extensive parameter Q;

[0014] The collected cathode-side electron temperature Anode side electron temperature With discharge voltage Substituting into the analytical formula, real-time calculations are performed to obtain the global average non-extensive parameter Q of the entire discharge channel of the Hall thruster. The analytical formula is as follows:

[0015]

[0016] Among them, Boltzmann constant , It represents the elementary charge.

[0017] As a preferred embodiment of the above scheme, in step S2, the cathode-side electron temperature... The sampling point is set inside the discharge channel near the hollow cathode, and the electron temperature on the anode side is... The sampling point is set inside the discharge channel near the anode.

[0018] More preferably, in step S2, the cathode-side electron temperature Anode side electron temperature The measurement can be performed using any of the following methods: Langmuir probe, fiber optic spectroscopy, or microwave diagnostics.

[0019] More preferably, in step S2, the discharge voltage Read directly from the power supply system of the Hall thruster.

[0020] More preferably, in step S3, a handheld computing device or an airborne computing device is used to complete the real-time calculation.

[0021] The beneficial effects of this invention are:

[0022] (1) Instead of using traditional distribution function fitting methods, the average non-extensive parameter Q of the discharge channel is directly obtained by measuring the relevant physical quantities of the anode and cathode, without complicated calculations;

[0023] (2) The original temperature and pressure measurement modules of the Hall thruster are reused throughout the process, without the need for new diagnostic hardware and sensors, resulting in extremely low measurement costs; no local probe fitting is required, and zero new hardware and zero structural modifications can be made simply by using the inherent macroscopic electrical parameters of the equipment.

[0024] (3) The measurement results are the average parameters of the entire discharge channel, which are suitable for the simulation of the Hall thruster system and the closed-loop control of the working condition;

[0025] (4) It is naturally suitable for strong nonequilibrium plasma conditions such as dual temperature distribution, anomalous transport, and number density reversal, and has high measurement accuracy;

[0026] (5) The analytical formula is concise and the calculation is fast, enabling real-time online monitoring and parameter calculation on track;

[0027] (6) Engineering applications of non-extensive parameters: The calculated non-extensive parameter Q can be directly used in scenarios such as statistical modeling of Hall thrusters, accurate thrust analysis, identification of anomalous transport conditions, online monitoring of electron number density reversal state, and optimization of thrust closed-loop control. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the Hall thruster. Detailed Implementation

[0029] The present invention will now be further described with reference to the accompanying drawings and embodiments.

[0030] A fast method for measuring the global average non-extensive parameter of a Hall thruster plasma includes the following steps:

[0031] Step S1: Steady-state operation of the equipment;

[0032] Start the Hall thruster, adjust the working fluid flow rate and discharge power to the target operating conditions, and wait for the parameters to stabilize: electron temperature and discharge voltage fluctuation ≤ ±5%, and remain stable for ≥ 30s to ensure that the plasma is in a steady-state discharge state.

[0033] The working fluid of the Hall thruster is an inert gas, preferably xenon.

[0034] Step S2: Collect cathode-side electron temperature Anode side electron temperature and discharge voltage Among them, the cathode-side electron temperature Anode side electron temperature ,volt.

[0035] like Figure 1 As shown, the Hall thruster is equipped with a cylinder 1, the inner cavity of which is a discharge channel 2. An anode 3 is located at the bottom of the discharge channel 2, and a hollow cathode 4 is located on the outer side of the opening of the cylinder 1. The cathode side electron temperature... The sampling point 5 is located inside the discharge channel 2 near the hollow cathode 4; the electron temperature on the anode side... The sampling point 6 is located inside the discharge channel 2 near the anode 3; the cathode side electron temperature Anode side electron temperature Any measurement method, such as Langmuir probe, fiber optic spectroscopy, or microwave diagnostics, can be used; however, this is not a limitation. Typically, the Hall thruster itself contains cathode-side electron temperature measurement capabilities. The electron temperature acquisition point on the anode side can be read directly without the need for additional sensors.

[0036] In addition, discharge voltage Read directly from the power supply system of the Hall thruster.

[0037] Step S3: Calculate the global average non-extensive parameter Q;

[0038] The collected cathode-side electron temperature Anode side electron temperature With discharge voltage Substituting into the analytical formula, real-time calculations are performed to obtain the global average non-extensive parameter Q of the entire discharge channel of the Hall thruster. The analytical formula is as follows:

[0039]

[0040] Among them, Boltzmann constant Electron volts / Kelvin; It represents the elementary charge.

[0041] For real-time calculations, it is best to use handheld or airborne computing devices; however, manual real-time calculations are also possible. The calculated "Q" value can be used for thrust modeling correction, ionization cross-section calibration, online monitoring of plasma conditions, and closed-loop control.

[0042] Example 1: 6kW Hall thruster

[0043] Equipment under test: 6kW Hall thruster, xenon working fluid, non-equilibrium steady-state operation; after steady-state operation, Langmuir probes are used to collect the electron temperature on the cathode side. Anode side electron temperature And calculate =5eV, =3eV, read the discharge voltage from the power supply system. =300V; Substituting into the formula, we get: Q = (5-3)eV / 300eV = 1 / 150.

[0044] Example 2: 1.5kW low-power Hall thruster

[0045] Equipment under test: 1.5kW Hall thruster, xenon working fluid, medium-low power steady-state operation; after steady-state operation, the cathode-side electron temperature was measured by spectral diagnostics. Anode side electron temperature And calculate =4eV =2eV, read the discharge voltage from the power supply system. =250V; Substituting into the formula, we get: Q = (4-2) eV / 250 eV =1 / 125.

Claims

1. A fast measurement method for the global average non-extensive parameter of a Hall thruster plasma, characterized in that, Includes the following steps: Step S1: Steady-state operation of the equipment; Start the Hall thruster, adjust the working fluid flow and discharge power to the target operating conditions, and wait for the parameters to stabilize: electron temperature and discharge voltage fluctuation ≤ ±5%, and remain stable for ≥ 30s to ensure that the plasma is in a steady-state discharge state. Step S2: Collect cathode-side electron temperature Anode side electron temperature and discharge voltage Among them, the cathode-side electron temperature Anode side electron temperature The unit is K; discharge voltage The unit is V; Step S3: Calculate the global average non-extensive parameter Q; The collected cathode-side electron temperature Anode side electron temperature With discharge voltage Substituting into the analytical formula, real-time calculations are performed to obtain the global average non-extensive parameter Q of the entire discharge channel of the Hall thruster. The analytical formula is as follows:

2. Among them, Boltzmann constant , It represents the elementary charge.

3. The fast measurement method for the global average non-extensive parameter of Hall thruster plasma according to claim 1, characterized in that: In step S2, the cathode-side electron temperature The sampling point is set inside the discharge channel near the hollow cathode, and the electron temperature on the anode side is... The sampling point is set inside the discharge channel near the anode.

4. A fast measurement method for the global average non-extensive parameter of a Hall thruster plasma according to claim 1 or 2, characterized in that: In step S2, the cathode-side electron temperature Anode side electron temperature The measurement can be performed using any of the following methods: Langmuir probe, fiber optic spectroscopy, or microwave diagnostics.

5. The fast measurement method for the global average non-extensive parameter of Hall thruster plasma according to claim 1, characterized in that: In step S2, the discharge voltage Read directly from the power supply system of the Hall thruster.

6. The fast measurement method for the global average non-extensive parameter of Hall thruster plasma according to claim 1, characterized in that: In step S3, real-time calculations are performed using handheld or airborne computing devices.

7. The fast measurement method for the global average non-extensive parameter of Hall thruster plasma according to claim 1, characterized in that: In step S1, the working medium is xenon gas.

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