Evaluation of Facility Effects on Ion Migration in a Hall Thruster Plume

5torr. The effects of background facility neutrals were characterized and isolated, which enabled precise and accurate estimation of thruster ion beam current and plume divergence. A set of guidelinesarerecommendedforFaradayprobedesign,experimentalmethodology,anddataanalysisthatareaimed at minimizing uncertainty of far-field Faraday probe measurements. These guidelines were shown to reduce the experimentally derived ion beam current by 10–20%, compared with conventional analysis techniques, and to reduce measurement uncertainty to approximately 3%. The reductions in measurement uncertainty and the increased capability to approximate the onorbit plume expansion from ground-based measurements are significant improvements that can be used for validation of numerical simulations and investigations of Hall thruster performance loss mechanisms. Nomenclature AC = cross-sectional geometric area of Faraday probe collector A0;1;2 = second-order polynomial coefficients G0;1;2;3;4 = Gaussian function coefficients