Experimental Investigation on Plasma Plume Potential

An experimental investigation is carried out to quantify the potential of the plasma plume emitted by an ion thruster type plasma source. A capability for efficient 2-D measurements of the plume profile is developed. The effects of plume expansion, plume charge-exchange (CEX) plasma, and facility background plasma on plume potential are investigated. For plasma source and vacuum chamber operating conditions considered in this paper, we find that the propellant CEX plasma is the primary factor that terminates the plume expansion process, and thus largely controls the magnitude of the plume potential with respect to the ambient.