The PIC Simulation Research On Characteristics Of Plasma Discharge In The Whole Channel Of Hall Thruster

Hall thruster is an electromagnetic plasma accelerator which is widely used in the field of space propulsion, the hollow coaxial cylindrical discharge channel is one of the core components of the thruster, and the plasma discharge characteristics under the effect of internal electromagnetic field inside the channel have significant influences on the performance of the thruster. Since the discharge voltage and working fluid flows are the crucial parameters which affect the plasma motions inside the thruster channel, researches on the processes of electron-atom collision, ion-ionization and acceleration under different physical conditions have great significances on generating a homogeneous and high-speed plasma beam in the Hall thruster.In this paper, a two-dimensional physical model which simulates the entire discharge channel Hall thruster is established base on the process of electromagnetic fields and plasma interaction, then the area of simulation and boundary conditions are confirmed. By using the PIC simulation method, the variation of wall channel potential, electron temperature, ion density distribution with the discharge voltage and mass flow is investigated, and the influences of mass flow on ion current, thrust force and propulsive efficiency are also discussed. The results show that when the discharge voltage is relatively low (250V-350V), the ionization region stays at 0.02m in the axial direction and the distribution on axial direction is relatively wide, the potential distribution merely changes with the growth of discharge voltage, the potential drop is concentrated at the channel outlet, and the accelerating region in the axial direction is short; while the discharge voltage continues to rise gradually (400-650V), the ionization region moves toward the anode gradually and the distribution region in axial direction decreased, the potential drop moves towards to the anode in axial direction gradually, the angel between the equipotential line and the channel wall increases, and the accelerating region expands in axial direction, when the discharge voltage range from 400V to 450V, the electron temperature appears to have a abrupt change phenomenon; when the discharge voltage is 700V, the ionization region is compressed and located near to the anode, but the acceleration region in axial direction increases greatly. The researches of discharge characteristics of Hall thruster with different mass flow show that: at lower mass flow (2-4mg/s), electron number density of ionization region increases with the increase of mass flows, the accelerating region is located in the narrow area near the channel outlet and the electron temperature increases, the potential drop is concentrated at the channel outlet, thrust force and ion current increase gradually, and the efficiency merely changes; at relatively high mass flows (5-6mg/s), the ionization region moves towards the anode gradually, accelerating region expends obviously in axial direction, the potential drop is mainly located between 0.015m and the channel outlet in axial direction, the angle between the equipotential line and the wall increases, the thrust force, ion current and propulsive efficiency decline gradually.