Numerical Analysis of the Sheath Structure and Discharge Current Oscillation in an Anode-Layer Hall Thruster

To investigate a role of a hollow anode for discharge stabilization in anode-layer hall thrusters, plasma dynamics inside a thruster was computed using the fully kinetic 2D3V Particle-in-Cell (PIC) and Direct Simulation Monte Carlo (DSMC) methods. The developed code successfully reproduced the measured discharge current waveform and threshold magnetic flux density for the oscillation onset. At the low magnetic flux density corresponding to the stable discharge case, ionization in the hollow anode was found vigorous and an ion sheath was created on the anode surface. This sheath contributed to the discharge stabilization. However, the amount of ionization in the anode decreased with the magnetic flux density, and the sheath structure changed to an electron sheath at the threshold magnetic flux density.