Plume measurements with the T5 xenon ion thruster

Abstract : Two measurement techniques for investigating performance and life-limiting characteristics of ion engines are applied to a 10-cm T5 xenon thruster: (1) Thrust vector stability is evaluated with four double-wire Langmuir probes, aligned in the form of a cross, which are placed in the exhaust plume and are translated by a motorized positioning system to balance the currents collected along two orthogonal axes. The thrust vector position is thereby tracked with an angular resolution of <0.01 deg and a response time of <5 s. (2) A plume-sampling mass spectrometer has been developed for measuring the xenon charge state distribution and the flux of erosion products from the discharge chamber as a function of operating point. To demonstrate the capability for real-time erosion monitoring, plume spectra that reveal trace amounts of metal ions are presented.