Method to Simulate Spacecraft Electrical Surface Charging due to Magnetoplasma Engine Plume-Spacecraft Interaction
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© 2018 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved. Electrical charging of spacecraft can lead to excessive charge differences on dissimilar materials leading to arcing and thus damage or destruction of external spacecraft components. One area of concern in using a magnetoplasma engines is how they will affect the spacecraft’s surface charge when active. A method to determine the interaction, specifically the electrical charging, caused by the plume of a magnetoplasma spacecraft engine and the adjoining spacecraft surfaces using a 3D axisymmetric numeric model is presented. Traditional methods use a continuum model to simulate plasma even when the plume’s Knudsen number > 1 and thus the continuum assumption is not valid. Therefore, the new method uses kinetic particle theory to numerically model a subset of individual ions to determine their trajectories and kinetic energies after ejection. The extrapolated data is used to predict how many ions will remain trapped by the engine’s magnetic field and interact with the spacecraft’s surfaces. The quantity and kinetic energy of all ions impacting spacecraft surfaces are then used to predict electrical charging. It was determined that 0.012% of ejected particles remain trapped in the engine’s magnetic field and impact under nominal operation but that this amount can vary significantly by changing the average exit velocity, magnetic field strength, and field geometry. Surface electrical charging was estimated to reach-15.61 V under nominal operation but can reach-20.89 V with different engine conditions. The erosion rate of different materials due to ion impact were presented in a previous paper.
author list (cited authors)
Martin, M. W., Staack, D., & Lalk, T.