Particle and power balances of hot-filament discharge plasmas in a multi-dipole device in the presence of a positively biased electrode

Abstract

The plasma potential is typically assumed to float above an anode potential by an amount that is a few times the electron temperature (T/sub e//e). The difference between the plasma potential and the anode potential can be estimated by considering the particle production and loss. However, it has been reported experimentally that the plasma potential of a steady-state plasma can be more negative than the anode potential with a potential dip ( approximately T/sub e//e) in front of the anode. Particle and power balances have been carried out to estimate the bulk plasma potential of a hot-filament discharge plasma produced in a multidipole plasma device. The bulk plasma potential dependence on the positive DC bias applied to the anode is analyzed, and the predicted characteristics of the plasma potential dependence are compared to the experimental results. A steady-state potential dip in front of the anode has been experimentally observed using emissive probes with the zero emission inflection point method, and the conditions for the potential dip formation have been derived. >