Secondary and Backscattered Electron Current Induced Differential Charging on a Triple Junction of Spacecraft

Abstract

This article discusses and analyzes the quantification of differential potential developed due to the effect of secondary electron yield (SEY) and backscattered electron yield (BEY) at adjacent dissimilar material surfaces present in a spacecraft. Subsequently, the differential potential creates electrostatic discharge (ESD). The threshold potential for generating the ESD is captured for the generalized case of differential charging on metallic patches embedded over a thin layer of the dielectric surface with the help of Spacecraft Plasma Interaction Experiments-II (SPIX-II) facilities. In view of the limitations of the experimental setup, numerical modeling is implemented to compute the differential charging for the recommended cases of plasma environment. The threat of an ESD event is indicated when the computed differential charging exceeds the ESD inception threshold voltage obtained from the experiments. Evaluation of the capacitance between material surfaces, which governs the timescale of differential charging, is carried out using the method of moments (MoM). The impact of diverse SEY and BEY of different materials on steady-state body potential is investigated. The validity of the analysis is also established with the results available in the open literature.