Anode geometry influence on LaB 6 cathode discharge characteristics

Abstract

The characterization of an electric propulsion device cathode is performed in the so-called diode configuration with an external anode. The anode acts as a physical boundary for the cathode plasma discharge; therefore, it influences cathode operation and performances. In this study, four different anodes—namely, a disk, a plate, a long cylinder, and a short cylinder—have been used with a flat disk LaB6 emitter 5\u2009A-class cathode to examine the anode geometry impact on cathode discharge properties. Current–voltage curves, discharge oscillations, electron parameters, and ion velocities have been measured for currents in the 2\u2009A to 12\u2009A range and xenon mass flow rates varied from 0.4\u2009mg/s to 1\u2009mg/s with a fixed cathode-to-anode distance. The set of results clearly supports the fact that the anode geometry strongly influences the cathode characteristics both at the macroscopic and the microscopic scale.