ELECTROSTATIC ION THRUSTERS - TOWARDS PREDICTIVE MODELING

Abstract

For satellite missions, thrusters have to be qualified in large vacuum vessels to simulate space environment. One caveat of these experiments is the possible modification of the beam properties due to the interaction of the energetic ions with the vessel walls. Impinging ions can produce sputtered impurities or secondary electrons from the wall. These can stream back into the acceleration channel of the thruster and produce co-deposited layers. Over the long operation time of thousands of hours, such layers can modify the optimized geometry and induce changes of the ion beam properties, e.g. broadening of the angular distribution and thrust reduction. To study such effects, a Monte Carlo code for the simulation of the interaction of ion thruster beams with vessel walls was developed. Strategies to overcome sputter limitations by additional baffles are studied with the help of this Monte-Carlo erosion code.