Density redistribution in a microsecond-conduction-time plasma opening switch

The first measurements of the line-integrated electron density in a coaxial microsecond-conduction-time plasma opening switch during switch operation are presented. Current conduction is observed to cause a radial redistribution of the switch plasma, with a large decrease in axial line density over most of the radial extent of the switch. A local reduction in line density of more than an order of magnitude occurs by the time opening begins. It is hypothesized that this density reduction allows the switch to open by an erosion mechanism. Initial numerical modeling efforts have reproduced the principal observed results.