Anode Geometry Effects on Ion Beam Energy Performance in Helicon Electrostatic Thruster

The ion beam energy performance in a helicon electrostatic thruster with various anode geometries was investigated. For discharge voltages from 100 to 300 V, the ion beam energy increased almost linearly with the discharge voltage. The rate of increase strongly depended on the anode inner diameter (ID). However, the ion beam energy was fit to a single linear function of the total input power irrespective of the anode ID. The effect of an insulation cover set on the side wall of the anode depended on the anode ID; while with the anode ID being equaled to that of the helicon source tube, i.e., 27 mm, the ion beam energy was decreased by about 30%, with the anode ID of 40 mm the electrostatic acceleration became negligible. Under typical operation conditions, the ion beam energy had a flat-hat profile with a diverging angle of 47°; the specific impulse, thrust efficiency, and propellant utilization efficiency evaluated from probe survey measurements were 2000 s, 9.7%, and 98%, respectively.