Numerical simulation study on the influence of channel geometry on discharge characteristics of low-power magnetically shielded Hall thrusters

Abstract By adjusting the relative position of the magnetic screen and the discharge channel, two types of 200 W low-power magnetically shielded Hall thrusters with three different B r e x i t / B r max ratios (the ratio of the radial magnetic field magnitude at the channel exit to the maximum radial magnetic field magnitude, taken at the channel mean diameter) using straight wall channel and chamfered wall channel geometries are designed. The discharge characteristics of the plasma under the two types of Hall thrusters are studied using the particle-in-cell (PIC) simulation, and the influence laws of the channel geometries on the thrust, specific impulse, and anode efficiency of the 200 W Hall thrusters are verified by the corresponding experimental testing. Both the results indicate that compared with the straight wall channel geometry of 200 W magnetically shielded Hall thrusters, the chamfered wall channel geometry will reduce the neutral gas density in the discharge channel, causing the propellant utilization efficiency to be lower, thus decreasing the ionization rate, ultimately reducing the performance of thruster. It explains and clarifies the reason for the dark gap phenomenon and the lower performance of the low-power magnetically shielded Hall thrusters.