Numerical Study On Effect Of Background Magnetic Field On Electron Behavior In Hall Thruster

Hall thruster is one of the electric thruster that the most widely used, the most mature technology in aerospace electric thruster, it can be used as a spacecraft device such an attitude control, orbital correction, orbit transfer, dynamic compensation and also can be used as a the main thruster in space detection and interstellar travel.As the larmor radius of ion is much larger than the characteristic length of thruster, the magnetic field only affects electron in Hall thruster. It can design a reasonable magnetic field to control behavior of the electron that the directly controlled factor in Hall thruster. In this paper, we study the ATON Hall thruster, based on the theory of electromagnetics, a two-dimensional model of the background magnetic field in a Hall thruster is established, the background magnetic field in Hall thrusters is calculated using the four methods respectively and the numerical results are obtained. Through analysis and comparison of the numerical results, the computational efficiencies of the four iterative methods are investigated. It is concluded that the optimal method is Gauss-Seidel iterative method by row-by-row and column-by-column.In some regions of the thruster, the interaction occur between plasma and thruster wall, the most complicated effect take place between electrons and wall. When the interaction between electrons and wall occurs again and again, it can causes serious corrosion to wall and influence ionization efficiency of working gas, as a result the lifetime of thruster and working efficiency will be affected. In this paper we use the above magnetic field as the background magnetic field of Hall thruster, based on the theory of plasma fluid, a two-dimensional fluid model is established, in our research we consider in electron time scale the ions and neutrals do not move, so in our model, we do not take the motion of the ions and neutrals into consideration. As a result, our present formulation only considers the behavior of the electrons. Research is about numerical study on the evolution of the electron density, the electron velocity and the electron temperature over time nearby ceramic wall in Hall thruster nozzle. From analysis of the numerical solution, it shows that when the magnetic field increase to the largest from the anode to export, the electron density gradually decreased to the minimum value; the inhomogeneity of electron density distribution with the increase of magnetic field gradient become gradually disappear near the inner wall, and the outer wall’s situation is the opposite; interaction between electron and wall on inner wall is severer than outer wall; the change of electron toroidal velocity is the outcome of combined action that between magnetic field and electric field; the existence of the magnetic field gradient can increases the electronic axial velocity and electrons are constrained very well on the place of the magnetic field intensity is stronger; due to the constraint that the magnetic field to electron, the difficulty of electrons cross the magnetic field become stronger as the increase of magnetic field.