INSTRUMENTS DESIGN AND ON-ORBIT TESTING DATA ANALYSIS FOR ION ENERGY DISTRIBUTION MEASUREMENT OF THE THRUSTER PLUME

Plasma ion energy per unit charge distribution can be measured effectively by Retarding Potential Analyzer(RPA).RPA should be designed specially according to plume plasma parameters range and feature of the Xe thruster.Major principles usable for good RPA design are discussed carefully.Design and the influence factors of RPA being used for on orbit spacecraft are described.On-orbit testing results show that desired data were achieved by the RPA.The data achieved by RPA are given and analyzed.