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Title: Improvement of the low frequency oscillation model for Hall thrusters

Abstract

The low frequency oscillation of the discharge current in Hall thrusters is a major aspect of these devices that requires further study. While the existing model captures the ionization mechanism of the low frequency oscillation, it unfortunately fails to express the dynamic characteristics of the ion acceleration. The analysis in this paper shows this is because of the simplification of the electron equation, which affects both the electric field distribution and the ion acceleration process. Additionally, the electron density equation is revised and a new model that is based on the physical properties of ion movement is proposed.

Authors:
;  [1]
  1. Yanshan University, College of Vehicles and Energy, Qinhuangdao 066004, Hebei (China)
Publication Date:
OSTI Identifier:
22611420
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Advances; Journal Volume: 6; Journal Issue: 8; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ACCELERATION; CAPTURE; CURRENTS; DISTRIBUTION; ELECTRIC DISCHARGES; ELECTRIC FIELDS; ELECTRON DENSITY; ELECTRONS; EQUATIONS; HALL EFFECT; IONIZATION; IONS; OSCILLATIONS; PHYSICAL PROPERTIES; THRUSTERS

Citation Formats

Wang, Chunsheng, E-mail: wangcs@hit.edu.cn, and Wang, Huashan. Improvement of the low frequency oscillation model for Hall thrusters. United States: N. p., 2016. Web. doi:10.1063/1.4961061.
Wang, Chunsheng, E-mail: wangcs@hit.edu.cn, & Wang, Huashan. Improvement of the low frequency oscillation model for Hall thrusters. United States. doi:10.1063/1.4961061.
Wang, Chunsheng, E-mail: wangcs@hit.edu.cn, and Wang, Huashan. Mon . "Improvement of the low frequency oscillation model for Hall thrusters". United States. doi:10.1063/1.4961061.
@article{osti_22611420,
title = {Improvement of the low frequency oscillation model for Hall thrusters},
author = {Wang, Chunsheng, E-mail: wangcs@hit.edu.cn and Wang, Huashan},
abstractNote = {The low frequency oscillation of the discharge current in Hall thrusters is a major aspect of these devices that requires further study. While the existing model captures the ionization mechanism of the low frequency oscillation, it unfortunately fails to express the dynamic characteristics of the ion acceleration. The analysis in this paper shows this is because of the simplification of the electron equation, which affects both the electric field distribution and the ion acceleration process. Additionally, the electron density equation is revised and a new model that is based on the physical properties of ion movement is proposed.},
doi = {10.1063/1.4961061},
journal = {AIP Advances},
number = 8,
volume = 6,
place = {United States},
year = {Mon Aug 15 00:00:00 EDT 2016},
month = {Mon Aug 15 00:00:00 EDT 2016}
}
  • Numerical simulations and experiments have been conducted to investigate the effects of a filter on low frequency oscillation in Hall thrusters. With one-dimensional quasineutral hydrodynamic model, the effects of filter components are studied by way of simulation computations. The simulation results show that with proper filter parameters, low frequency oscillation can be stabilized. Further, an eigenvalue study of the linear stability has been performed and the stability conditions according to filter parameters are given. Finally, the theoretical analysis is validated qualitatively through experiments.
  • In order to study the effect of magnetic field strength on low frequency oscillation in Hall thrusters, experiments were carried out with different operating parameters. Experimental results show that the effect of magnetic field strength on the low frequency oscillation changes with operating parameters. In the decline zone of magnetoampere characteristic curve, low frequency oscillation increases with the increase of magnetic field strength at low mass flow rate, while decreases with the increase of magnetic field strength at high mass flow rate. With further experiments and numerical simulations, it is found that the change of electron current at low massmore » flow rate and the change of ion current at high mass flow rate account for the variations of low frequency oscillation. Finally, the physical analysis is performed.« less
  • The low-frequency oscillation characteristics of a Hall thruster were investigated by varying the dielectric wall temperature. Experimental results indicate that increasing the dielectric wall temperature can result in an increase in the amplitude of low-frequency oscillation and a slight decrease in its frequency. Physical analysis revealed that this change is related to the secondary electron emissions at different dielectric wall temperatures. The evidence suggests that this technique can serve as an effective way for future studies to examine how secondary electron emissions affect a discharging thruster.
  • It is found that the low frequency oscillations have modulating action on high frequency instabilities in Hall thrusters. The physical mechanism of this modulation is discussed and verified by numerical simulations. Theoretical analyses indicate that the wide-range fluctuations of plasma density and electric field associated with the low frequency oscillations affect the electron drift velocity and anomalous electron transport across the magnetic field. The amplitude and frequency of high frequency oscillations are modulated by low frequency oscillations, which show the periodic variation in the time scale of low frequency oscillations.
  • The breathing mode is a low frequency, longitudinal bulk instability observed in a majority of Hall thrusters. Its occurrence is accompanied by wide, regular discharge current oscillations in the 10-30 kHz range. A concise outline of the prevailing interpretations of this mode is provided, followed by an overview of a recently proposed theory. It is eventually shown that this ionization instability is not related to the motion of the ionization front but to an ionization predator-prey cycle, the former phenomenon being rather a consequence of the latter.