Particle in cell simulation of plasma thrusters

Abstract

Summary form only given. The Particle-in-Cell (PIC) method was used to study various plasma thruster concepts: Stationary Plasma Thruster (SPT), High Efficiency Multistage Plasma Thruster (HEMP-T) and the cylindrical Hall thruster (CHT). In all cases PIC proved itself as a powerful tool, delivering important insight into the basic physics of the different thruster concepts. Two dimensional Particle-in-Cell code with Monte Carlo Collisions (PIC-MCC) was applied to simulate the operation of SPT and HEMP thrusters, in particular the plasma properties in the discharge chamber due to the different magnetic field configurations. Special attention was paid to the simulation of plasma particle fluxes on the thrusters' channel surfaces. The model resolves 2 spatial (rz) and 3 velocity components (2d3v). Using ion flux distributions calculated with PIC-MCC, the wall erosion of both thruster types was studied with the binary collision approximation (BCA) based Monte-Carlo code SDTrimSP1. In order to resolve the electron cross-field transport selfconsistently, accounting for plasma azimuthal dynamics, a new, fully three-dimensional PIC-MCC model was developed2. The model utilizes an equidistant Cartesian grid which explicitly assures momentum conservation and zero self forces. The simulation treats electrons, Xe+ ions and neutral Xenon atoms. All relevant collisional processes are included in the model. The dynamics of the background neutral gas is self-consistently resolved with direct simulation Monte Carlo. The model was applied to simulate the operation of a 100 W CHT thruster3. In the simulation a spoke rotating with the velocity of about 2 km/s was observed in the thruster channel, which agrees very well with the experiment4. The initial position of the spoke was found to be strongly correlated with the cathode placement. The simulation has shown that the rotating spoke is associated with the strong azimuthal depletion of the neutral gas, which indicates the importance of the ionization for this instability.