Numerical Simulation Of Hall Thruster Discharge Channel Wall Erosion

Hall thruster, a type of electric propulsion with long lifetime, is an ideal low thrust device for long missions such as satellite station keeping and deep space exploration. Because of its good overall performance, such as high specific impulse, high propulsion efficiency and long lifetime, Hall thruster has been widely used for space explore missions of various spacecraft. Recently, the lifetime challenge of Hall thruster has been raised by the requirement of applying the thruster to more complex propulsion tasks.The major factor that influences properties of Hall thruster is discharge channel wall sputtering erosion. The main structure of Hall thruster is its coaxial discharge channel. A radial magnetic field that is orthogonal to the axial electric field causing a crossed-field in its specialized coaxial discharge channel, and electrons are restrained in the channel by this field. Ions are generated through electron-impact ionization of propellant. The thrust in Hall thruster is generated by ions being accelerated through the discharge channel by the electric field. Because of the imperfect configuration of the electric field and magnetic field, the ion flux is not ideally focused and some energetic ions sputtering on the discharge channel, causing channel wall erosion. Once the channel wall is eroded off, the magnetic field coils are exposed and further degradation may occur, affecting the stable performance of the thruster. So it is necessary to understand the corrosion mechanism of Hall thruster for its further development.A two-dimensional axisymmetric fully-kinetic PIC-MCC model is developed to study the erosion of the channel wall of the Hall thruster in this paper. The distribution of the particles is tracked by the fully-kinetic PIC-MCC method. The erosion model is established based on the sputtering model of the wall, and the erosion rate is calculating using the distribution of ions and tabulated data of the sputter yield of the wall material.In this paper, the wall erosion evolution of SPT-100 type Hall thruster is simulated, and the research shows that the simulated results match well with the experimental results. Thus, the simulation results verify the validity of the method used in this paper. The relation between operation conditions and wall erosion of SPT-100 is studied. What’s more, the effect of pre-ionization on erosion of the channel wall of the second generation P70 type Hall thruster is studied in the paper. The results obtained indicate that the erosion of the channel wall increases as the pre-ionization ratio increases. Thus, in the designing of the new generation Hall thruster, more aspects must be considered to achieve better performance and longer life of the thruster.