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Influence of the position relationship between the cathode and magnetic separatrix on the discharge process of a hall thruster

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Plasma Science and Technology 2024年第1期26卷 74-81页

作者：曹希峰麻洪宁夏国俊刘辉赵方舟王宇航陈巨辉 School of Mechanical and Power Engineering Harbin University of Science and TechnologyHarbin 150001People’s Republic of China Shanghai Institute of Satellite Engineering Shanghai 20040People’s Republic of China Lab of Plasma Propulsion Harbin Institute of TechnologyHarbin 150001People’s Republic of China

Previous studies have shown that there is an obvious coupling relationship between the installation location of the external cathode and the magnetic separatrix in the plume region of a hall *** this paper,the particle-in-cell simulation method is used to compare the thruster discharge process under the conditions of different position relationships between the cathode and the magnetic *** comparing the distribution of electron conduction,potential,plasma density and other microscopic parameters,we try to explain the formation mechanism of the discharge *** simulation results show that the cathode inside and outside the magnetic separatrix has a significant effect on the distribution of potential and plasma *** the cathode is located on the outer side of the magnetic separatrix,the potential above the plume region is relatively low,and there is a strong potential gradient above the plume *** potential gradient is more conducive to the radial diffusion of ions above the plume,which is the main reason for the strong divergence of the *** distribution of ion density is also consistent with the distribution of *** the cathode is located on the outer side of the magnetic separatrix,the radial diffusion of ions in the plume region is ***,by comparing the results of electron conduction,it is found that the traiectories of electrons emitted from the cathode are significantly different between the inner and outer sides of the magnetic *** is mainly because the electrons are affected by the magnetic mirror effect of the magnetic tip,which makes it difficult for the electrons to move across the magnetic *** is the main reason for the difference in potential *** this paper,the simulation results of macroscopic parameters under several conditions are also compared,and they are consistent with the experimental *** cathode is located on the inner side of the ma

关键词： hall thruster cathode magnetic separatrix

A novel optical emission spectroscopy method for diagnostics of contribution of different ionization mechanisms and flux of ions in different valences in discharge channel of a hall thruster

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Chinese Journal of Aeronautics 2024年第4期37卷 294-307页

作者： Yanfei WANG Ximing ZHU Renqiu ZOU Shilin YAN Junwei JIA Zhongxi NING Daren YU School of Energy Science and Engineering Harbin Institute of TechnologyHarbin 150001China Key Laboratory of Aerospace Plasma Propulsion Ministry of Industry and Information TechnologyHarbin 150001China Beijing Orient Institute of Measurement and Test Beijing 100094China Beijing Aerospace Long March Aircraft Research Institute Beijing 100076China

The mass application of hall thrusters poses the need for a diagnostic method of ionization mechanism in the discharge channel to boost the iteration and optimization of thruster *** work presents an Optical Emission Spectroscopy (OES) method for diagnostics of the contribution of different ionization mechanisms and the flux of ions in different valences in the discharge channel of a hall *** emission spectra in the discharge channel are analyzed by jointly utilizing a collisional-radiative model,an ionization-excitation model,and a flux-conservation *** is found that the intensities of some spectral lines can be converted into the reaction rates of collision processes,e.g.,electron-induced excitation and ionization *** latter can further be used to determine the evolutions of particle fluxes by utilizing the conservation law of *** novel method is demonstrated on a kilo-watt hall *** evolutions of several parameters are determined using this method along the discharge channel,including the ionization rates of different mechanisms,particle fluxes,particle densities,and particle *** novel method can be further developed by being jointly utilized with spectral imaging and tomography techniques,enabling diagnostics of multi-dimensional distributions of the above-mentioned parameters in the discharge channel and near-field plume.

关键词： hall thruster Optical emission spectroscopy Ionization mechanism Particle flux Divalent ion

Growth mechanism and characteristics of electron drift instability in hall thruster with different propellant types

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Chinese Physics B 2024年第1期33卷 511-522页

作者：陈龙阚子晨高维富段萍陈俊宇檀聪琦崔作君 School of Science Dalian Maritime UniversityDalian 116026China

The existence of a significant electron drift instability(EDI) in the hall thruster is considered as one of the possible causes of the abnormal increase in axial electron mobility near the outlet of the channel. In recent years, extensive simulation research on the characteristics of EDI has been conducted, but the excitation mechanism and growth mechanism of EDI in linear stage and nonlinear stage remain unclear. In this work, a one-dimensional PIC model in the azimuthal direction of the thruster near-exit region is established to gain further insights into the mechanism of the EDI in detail, and the effects of different types of propellants on EDI characteristics are discussed. The changes in axial electron transport caused by EDI under different types of propellants and electromagnetic field strengths are also examined. The results indicate that EDI undergoes a short linear growth phase before transitioning to the nonlinear phase and finally reaching saturation through the ion Landau damping. The EDI drives a significant ion heating in the azimuthal direction through electron–ion friction before entering the quasi-steady state, which increases the axial mobility of the electrons. Using lighter atomic weight propellant can effectively suppress the oscillation amplitude of EDI, but it will increase the linear growth rate, frequency, and phase velocity of EDI. Compared with the classical mobility, the axial electron mobility under the EDI increases by three orders of magnitude, which is consistent with experimental phenomena. The change of propellant type is insufficient to significantly change the axial electron mobility. It is also found that the collisions between electrons and neutral gasescan significantly affect the axial electron mobility under the influence of EDI, and lead the strength of the electric field to increase and the strength of the magnetic field to decrease, thereby both effectively suppressing the axial transport of electrons.

关键词： hall thruster electron drift instability axial electron mobility particle-in-cell simulation

Influence of acceleration stage electrode voltage on the performance of double-stage hall effect thruster with adjustable zero magnetic point

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Plasma Science and Technology 2024年第6期26卷 60-69页

作者：陈龙高维富崔作君段萍许雪松阚子晨檀聪琦陈俊宇 School of Science Dalian Maritime UniversityDalian 116026People’s Republic of China

The configuration of electrode voltage and zero magnetic point position has a significant impact on the performance of the double-stage hall effect thruster. A 2D-3V model is established based on the two-magnetic peak type double-stage hall thruster configuration, and a particle-in-cell simulation is carried out to investigate the influences of both acceleration electrode voltage value and zero magnetic point position on the thruster discharge characteristics and *** results indicate that increasing the acceleration voltage leads to a larger potential drop in the acceleration stage, allowing ions to gain higher energy, while electrons are easily absorbed by the intermediate electrode, resulting in a decrease in the anode current and ionization rate. When the acceleration voltage reaches 500 V, the thrust and efficiency are maximized, resulting in a 15%increase in efficiency. After the acceleration voltage exceeds 500 V, a potential barrier forms within the channel, leading to a decrease in thruster efficiency. Further study shows that as the second zero magnetic point moves towards the outlet of the channel, more electrons easily traverse the zero magnetic field region, participating in the ionization. The increase in the ionization rate leads to a gradual enhancement in both thrust and efficiency.

关键词： hall thruster particle-in-cell simulation intermediate electrode zero magnetic point

Investigation of short-channel design on performance optimization effect of hall thruster with large height–radius ratio

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Plasma Science and Technology 2022年第2期24卷 1-9页

作者：范昊天丁永杰牟春锦魏立秋李鸿于达仁 Plasma Propulsion Lab Institute of Advanced PowerHarbin Institute of TechnologyHarbin 150001People's Republic of China Key Laboratory of Aerospace Plasma Propulsion Ministry of Industry and Information TechnologyHarbin 150001People's Republic of China

In this study,the neutral gas distribution and steady-state discharge under different discharge channel lengths were studied via numerical *** results show that the channel with a length of 22 mm has the advantage of comprehensive discharge *** this time,the magnetic field intensity at the anode surface is 10%of the peak magnetic field *** analysis shows that the high-gas-density zone moves outward due to the shortening of the channel length,which optimizes the matching between the gas flow field and the magnetic field,and thus increases the ionization *** outward movement of the main ionization zone also reduces the ion loss on the wall ***,the propellant utilization efficiency can reach a maximum of 96.8%.Moreover,the plasma potential in the main ionization zone will decrease with the shortening of the *** excessively short-channel will greatly reduce the voltage utilization *** thrust is reduced to a minimum of 46.1 m ***,because the anode surface is excessively close to the main ionization zone,the discharge reliability is also difficult to *** was proved that the performance of hall thrusters can be optimized by shortening the discharge channel appropriately,and the specific design scheme of short-channel of HEP-1350 PM was defined,which serves as a reference for the optimization design of hall thruster with large height–radius *** shortchannel design also helps to reduce the thruster axial dimension,further consolidating the advantages of lightweight and large thrust-to-weight ratio of the hall thruster with large height–radius ratio.

关键词： hall thruster large height-radius ratio short-channel design discharge performance numerical simulation

A fast convergence fourth-order Vlasov model for hall thruster ionization oscillation analyses

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Plasma Science and Technology 2022年第2期24卷 117-126页

作者： Zhexu WANG Rei KAWASHIMA Kimiya KOMURASAKI The University of Tokyo 7-3-1 Hongo Bunkyo Tokyo 113-8656 Japan

A 1D1 V hybrid Vlasov-fluid model was developed for this study to elucidate discharge current oscillations of hall thrusters(HTs).The Vlasov equation for ions velocity distribution function with ionization source term is solved using a constrained interpolation profile conservative semiLagrangian *** fourth-order weighted essentially non-oscillatory(4 th WENO)limiter is applied to the first derivative value to minimize numerical oscillation in the discharge oscillation *** fourth-order accuracy is verified through a 1 D scalar test *** and high-resolution features of the Vlasov model are confirmed by simulating the test cases of the Vlasov–Poisson system and by comparing the results with a particle-in-cell(PIC)method.A1 D1 V HT simulation is performed through the hybrid Vlasov *** ionization oscillation is *** oscillation amplitude and plasma density are compared with those obtained from a hybrid PIC *** comparison indicates that the hybrid Vlasov-fluid model yields noiseless results and that the steady-state waveform is calculable in a short time period.

关键词： hall thruster ionization oscillation Vlasov equation semi-Lagrangian method

Numerical study of the effect of aft-loaded magnetic field on multiple ionizations in hall thruster

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Plasma Science and Technology 2022年第7期24卷 45-52页

作者：曾德迈李鸿刘金文丁永杰魏立秋于达仁毛威 Lab of Plasma Propulsion Harbin Institute of TechnologyHarbin 150001People's Republic of China Key Laboratory of Aerospace Plasma Propulsion Ministry of Industry and Information TechnologyHarbin 150001People's Republic of China Qingdao Haier Smart Technology Qingdao 266100People's Republic of China Beijing Institute of Control Engineering Beijing 100190People's Republic of China

It is assumed that the shift of a strong magnetic field region with a positive gradient from exit plane to outside, namely the transit from a normal loaded magnetic field to an aft-loaded one, enhances the multiple ionization process in the magnetically shielded hall thruster. To confirm this conjecture, a comparative study is carried out numerically with a particle-in-cell method. The simulation results prove that compared with the normal loaded magnetic field, the application of aft-loaded magnetic field enhances the multiple ionization process. This study further analyzes the ionization characteristics of the transition from low-charged ions to high-charged ions under two magnetic field conditions and the influence of the magnetic strength of aft-loaded magnetic field on the multiple ionization characteristics. The study described herein is useful for understanding the discharge characteristics of hall thruster with an aft-loaded magnetic field.

关键词： hall thruster aft-loaded magnetic field multiple ionization electron temperature

Study on the characteristics of non-Maxwellian magnetized sheath in hall thruster acceleration region

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Plasma Science and Technology 2022年第7期24卷 102-111页

作者：陈龙安宇豪孙少娟段萍姜博瑞杨叶慧崔作君 College of Science Dalian Maritime UniversityDalian 116026People's Republic of China

The secondary electron emission(SEE) and inclined magnetic field are typical features at the channel wall of the hall thruster acceleration region(AR), and the characteristics of the magnetized sheath have a significant effect on the radial potential distribution, ion radial acceleration and wall erosion. In this work, the magnetohydrodynamics model is used to study the characteristics of the magnetized sheath with SEE in the AR of hall thruster. The electrons are assumed to obey non-extensive distribution, the ions and secondary electrons are *** on the Sagdeev potential, the modified Bohm criterion is derived, and the influences of the non-extensive parameter and magnetic field on the AR sheath structure and parameters are discussed. Results show that, with the decrease of the parameter q, the high-energy electron leads to an increase of the potential drop in the sheath, and the sheath thickness expands accordingly,the kinetic energy rises when ions reach the wall, which can aggravate the wall *** the magnetic field inclination angle in the AR of the hall thruster, the Lorenz force along the x direction acting as a resistance decelerating ions becomes larger which can reduce the wall erosion, while the strength of magnetic field in the AR has little effect on Bohm criterion and wall potential. The propellant type also has a certain effect on the values of wall potential,secondary electron number density and sheath thickness.

关键词： hall thruster magnetized sheath non-extensive distribution secondary electron emission

Machine learning-based method to adjust electron anomalous conductivity profile to experimentally measured operating parameters of hall thruster

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Plasma Science and Technology 2022年第6期24卷 148-156页

作者： Andrey SHASHKOV Mikhail TYUSHEV Alexander LOVTSOV Dmitry TOMILIN Dmitrii KRAVCHENKO JSC'Keldysh Research Center' 8 Onezhskaya St.Moscow 125438Russia

The problem of determining the electron anomalous conductivity profile in a hall thruster,when its operating parameters are known from the experiment,is *** solve the problem,we propose varying the parametrically set anomalous conductivity profile until the calculated operating parameters match the experimentally measured ones in the best *** axial 1D3V hybrid model was used to calculate the operating parameters with parametrically set *** of the conductivity profile was performed using Bayesian optimization with a Gaussian process(machine learning method),which can resolve all local minima,even for noisy *** calculated solution corresponding to the measured operating parameters of a hall thruster in the best way proved to be unique for the studied operating modes of *** local plasma parameters were calculated and compared to the measured ones for four different operating *** results show the qualitative *** agreement between calculated and measured local parameters can be improved with a more accurate model of plasma-wall interaction.

关键词： hall thruster anomalous conductivity machine learning Bayesian optimization Gaussian process electric propulsion