Polarity dependent plasma dynamics in a tri-plate POS

An experimental comparison is presented of a planar, tri-plate POS operated in both negative and positive polarity. For the same initial conditions, the conduction time is longer in positive than in negative polarity and interferometry reveals marked differences in the evolution of the plasma distribution. 2-D Hall/MHD calculations are also presented for a situation similar, but not identical, to the experiment. We conclude that Hall physics can play a major role in the POS plasma dynamics during the conduction phase of the POS and in determining the initial conditions for the opening phase.