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Development of a Differential Radio Frequency Ion Thruster for Precision Spacecraft Control

A novel miniaturized gridded ion thruster is under development by the Electric Propulsion Group of QinetiQ in collaboration with the University of Southampton to provide a single propulsion system capable of providing both coarse and fine spacecraft control manoeuvres. The thruster concept is expected to provide sub micro-Newton thrust control and resolution by the differential control of opposing ion beams extracted from a common plasma discharge. A radio frequency inductive discharge is used as the ionization process. Prototype and breadboard models of the thruster have been manufactured and tested at the EP facilities of QinetiQ. Following discharge and geometry investigations, two simultaneous ion beams were successfully extracted at RF input powers between 45W - 50W and flow rates between 0.06 mgs -1 - 0.11 mgs -1 . Single-ended operation of the thruster enabled thrust levels of 200�N-480�N at RF powers between 22W – 29W and flow rates of 0.03 mgs -1 - 0.05 mgs -1 . Further analysis of thruster performance and investigations into the differential control of the ion beams continues.