Experimental characterization of ID-Hall, a double stage Hall thruster with an inductive ionization stage

Abstract

We present experimental results on the characterization of ID-Hall, a double stage Hall thruster with an inductively coupled magnetized ionization stage. This first experimental prototype of ID-Hall operates in a low power regime, typically below 400 W. The purpose of this work is not only to study the properties of ID-Hall and provide directions for optimization but also, and more generally, to study the relevance of the double stage concept with respect to important physical issues such as current oscillations and anomalous electron transport. We present experimental measurements of the current–voltage characteristics, extracted ion beam current (Faraday cup measurements), and ion energy and angular distribution functions (RPA measurements) in single and double stage regimes of operation, as a function of DC voltage and RF power. The results demonstrate that ions can be extracted from the inductive RF ionization stage even under conditions where the applied DC voltage is not sufficient to ionize the gas flow, i.e., ID-Hall can indeed operate in a double stage regime. At intermediate voltages, the overshoot observed in the current–voltage characteristics of single stage thrusters disappears in double stage operation, indicating a decrease in anomalous electron transport. Time-resolved and time-averaged ion energy distribution measurements show a coupling between ion energy, breathing mode oscillations, and the magnetic configuration of ID-Hall.