3D plume modeling of SPT-100

Hall thrusters are a spacecraft propulsion device for orbit maintenance and north-south station keeping. One of the concerns about Hall thrusters is the sputtering of high energy ions which could result in the erosion of sensitive surface coatings used for solar cell elements and thermal control. In this thesis, a 3D DSMC-PIC hybrid kinetic simulation of a well known, stationary plasma thruster SPT-100 plume modeling was performed using a hybrid MPI-GPU AMR code CHAOS. Xe atoms, Xe+, and Xe+2 ions are modeled using a kinetic approach. Modeling electrons using a kinetic approach is not feasible in today's computational power for a Hall thruster plume. Thus three different models are used to compute the plasma potential. First, Boltzmann and polytropic models are used for electric potential calculations. Current density values obtained from both electron models are compared with previous experimental measurements and simulations in the literature. It was seen that the polytropic model shows better agreement with the experimental measurements than the Boltzmann model and previous studies. In order to implement more detailed models, an electron fluid model is implemented and is solved on an AMR octree grid using the preconditioned conjugate gradient method. Current density comparisons of the electron fluid model with the experimental measurements showed a worse comparison than the polytropic model for the selected parameters. The implemented electron fluid model is then compared with ion energy distributions from flight measurements and previous simulations and showed good agreement for the chosen parameters. In order to investigate the influence of solar panel voltage on a spacecraft plume, simulations using the electron fluid and the polytropic models were compared. It was seen that the spatial distribution of ions in the core plume and in the backflow region are similar for both electron models. Finally, sputtering calculations were performed and it was seen that the energies of ions that hit the solar panel are smaller than the threshold energy of aluminum, and so that there would be insignificant sputtering. This is because neutralized particles in the vicinity of the solar panel create a shield that protects the solar panel from the high energy CEX ions