Unstructured 3D PIC/DSMC modeling of FEEP thruster backflow contamination

Summary form only given. A three-dimensional PIC/DSMC numerical code is used to study a charge-exchange (CEX) ion backflow from a Field-Emission-Electric-Propulsion (FEEP) thruster. Contamination from backflow CEX ions generated in the plume can be an important issue in the spacecraft propulsion system operation. The effect of the neutralizer on the back-flow current is analyzed. The results are compared with previous three-dimensional simulations. The code used for the FEEP plumes simulations is developed on the unstructured tetrahedral grids. Neutral particles are simulated using Direct Simulations Monte Carlo (DSMC) method while charged particles follow the Particle in Cell (PIC) algorithm. Simulated collisions include elastic neutral-neutral, both elastic and CEX ion-neutral and charge particle collisions.