A radio-frequency generator for ion thrusters based on a Class-E power circuit

Abstract

AbstractOperating a radio-frequency ion thruster (RIT) requires a high frequency current flowing through an induction coil in order to ignite and maintain an inductively coupled plasma discharge (ICP). Several methods to create that current have been demonstrated and evaluated regarding complexity, flexibility and efficiency. Especially in space applications reliability and minimal power loss is crucial to comply to strict mission requirements. As one of the leanest concepts in terms of required components and nevertheless highest possible efficiency, the Class-E power circuit has proven itself as a well suited radio-frequency generator (RFG) of a RIT system. However, electrical performance and especially electromagnetic compatibility (EMC) during operation have not been evaluated, but are essential if the system is intended for use in space. In order to fill this gap and bring the Class-E circuit into the fold of established RFG concepts, a prototype was designed, built, and used to operate a RIT-10. For reference, a conventional Half-Bridge RFG was tested under the same operating conditions. Further investigations are concerned with EMC behaviour of both devices and show that Class-E circuit exhibits significantly lower electromagnetic emission during operation compared to the Half-Bridge reference.