Ion thruster plumes interacting with ambient atomic oxygen are simulated using direct simulation Monte Carlo/particle-in-cell code with automatic mesh refinement/octree grids. Because of the disparity among the species concentrations and velocities, particle weighting factors with multiple species weighting time steps have been used. To calculate the elastic cross section for collisions, the variable hard sphere collision cross section was compared with the higher-fidelity Lennard–Jones model and found to agree well at the relevant collision energies. Because momentum and charge exchange cross sections for and O are not available in the literature, analytic approaches were used to infer these values. The simulations provide a number of interesting results about the role of and collisions. The effect of incoming freestream atomic oxygen direction on the ion thruster plume at 185 and 300 km altitudes was studied by changing the plume angle with respect to the freestream atomic oxygen, corresponding to satellite orientation change in orbit. It was observed that the freestream atomic oxygen affects the backflux of Xe at the lower altitude. This effect lessens as the altitude increases and is not observable at 300 km, and it was observed that Xe fluxes scale in a linear fashion with the density of O. The spatial distribution of the xenon ion fluxes was not influenced by collisions with freestream atomic oxygen.
Particle Simulations of the Effects of Atomic Oxygen on Ion Thruster Plumes
Journal of Spacecraft and Rockets ; 55 , 5 ; 1154-1165
2018-04-30
12 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
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