Sputtering of cubic metal crystals by low-energy xenon-ions
ES Wise and MS Liu and T Miller, COMPUTATIONAL MATERIALS SCIENCE, 107, 102-109 (2015).
Ion thrusters are playing an increasingly important role on-board satellites, largely because of their high fuel efficiency. As a result, there has been strong interest in improving their performance and extending their operational lifetimes. A key factor limiting these lifetimes is the sputtering of atoms from thruster components. Ion thrusters generally use molybdenum grids, however it is thought that non-standard grid materials may prove more robust to this damage. High manufacturing costs and lengthy testing times limit the ability of researchers to investigate this experimentally. Computational methods provide an alternative mechanism for assessing potential alternative grid materials. Atomistic simulations of sputtering have been shown to be accurate for a number of systems, and so in this work we attempt to establish this effectiveness for a much wider range of materials. Atomistic simulations additionally have the potential to elucidate the dynamics of sputtering better than other simulation methodologies. To this end, we used atomistic simulations to compute sputter yields for 12 different metals under bombardment by xenon-ions with kinetic energies of between 100 eV and 1 keV. We found that the method showed great promise, but that the sputter yield is dependent on the exact choice of interatomic potential. We went on to examine sputtering of molybdenum in greater detail and compared our results with commonly used empirical models, the TRIM simulation program and experimental data from the literature. Some similarities and some differences were observed, however atomistic simulations are shown to generally produce accurate yields and a more realistic representation of the dynamics of sputtered particles. Crown Copyright (C) 2015 Published by Elsevier B.V. All rights reserved.
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