Potential Contours in Ion Focusing Hall Thruster

The Embedded Electrode Hall Effect Thruster is a modified 10 kW T-220HT with embedded graphite electrodes within the channel wall to study ion focusing for improved thrust-to-power ratio. Previous experiments with the thruster have demonstrated increased performance on xenon with biased electrodes caused by increases in ion energy, propellant efficiency, and a reduction in the plume divergence angle. In this paper, the in-channel plasma potential is experimentally mapped with emissive probes to determine the effect of the cusp-magnetic fields and wall electrodes on the plasma. The resultant potential contours indicate a significant compression in the potential field and acceleration region by 4 – 10 cm when the electrodes are biased to 30 V and creation of domed high-potential regions that are responsible for focusing electric fields.