Particle and power balances of hot-filament discharge plasmas in a multidipole device

This paper considers particle and power balances to estimate the bulk plasma potential of a hot-filament discharge plasma produced in a multidipole plasma device. The bulk plasma potential dependence on positive dc bias applied to an anode is analyzed, and the predicted characteristics of the plasma potential are compared to the experiment. It is shown that the plasma potential can be more positive or more negative than the anode bias potential. When the potential is more negative, a steady-state potential dip in front of an anode is observed using emissive probes with the zero-emission inflection point method. Conditions for the potential dip formation are discussed.