  The Particle-in-Cell (PIC) method was used to study two different ion
thruster concepts - Stationary Plasma Thrusters (SPT) and High Efficiency
Multistage Plasma Thrusters (HEMP-T), 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. In both cases, PIC proved itself as a powerful
tool, delivering important insight into the basic physics of the different
thruster concepts. The simulations demonstrated that the new HEMP thruster
concept allows for a high thermal efficiency due to both minimal energy
dissipation and high acceleration efficiency. In the HEMP thruster the plasma
contact to the wall is limited only to very small areas of the magnetic field
cusps, which results in much smaller ion energy flux to the thruster channel
surface as compared to SPT. The erosion yields for dielectric discharge channel
walls of SPT and HEMP thrusters were calculated with the binary collision code
SDTrimSP. For SPT, an erosion rate on the level of 1 mm of sputtered material
per hour was observed. For HEMP, thruster simulations have shown that there is
no erosion inside the dielectric discharge channel.
