Quantifying Uncertainty in Predictions of Spacecraft Erosion Induced by a Hall Thruster

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Quantifying Uncertainty in Predictions of Spacecraft Erosion Induced by a Hall Thruster

Meyer, Mackenzie E. / Byrne, Matthew P. / Boyd, Iain D. / Jorns, Benjamin A.

The impact of sputtering yield model uncertainty on the predicted erosion of a meshed reflector wire exposed to a Hall effect thruster plume is investigated. Quantifying this uncertainty is critical for making informed assessments of reflector lifetime. The erosion is modeled by assuming known ion current density and energy distribution at the location of the wire. The wire surface is then discretized, and wear is evaluated incrementally over time. The confidence in model predictions is quantified where the major source of uncertainty is assumed to stem from the material sputtering yield. The model is run to simulate reflector erosion after 10 h of exposure to a 3 kW class Hall thruster operating at 300 V. The simulated results then are compared to experimental measurements from a dedicated wear test performed on a series of mesh coupon samples. The experimental results are shown to fall largely within the 95% credible intervals from model predictions, though the uncertainty in the maximum predicted erosion is found to be up to 190% of the maximum predicted erosion. These results are discussed in the context of predicting lifetime of reflectors on orbit and the need for margin in this component design.