Plasma and current asymmetry effects on the performance of a radial POS

The effect of plasma and current asymmetries on a radial geometry based plasma opening switch (POS) operated on the 1 μs time scale into an inductive short circuit load has been investigated. The study was performed at the ACE 2 facility, a 240 kV, 1 MJ Marx with a 3 μs quarter period. In this configuration the active POS area consisted of an annular, parallel plate region with the power flowing radially inward. The ACE 2 annular POS region extended from an upstream outer 56 cm diameter to a downstream inner 25 cm diameter with plasma supplied by flashboards using peaking capacitors through a transparent anode. The effect of both current and plasma asymmetries on the POS performance was evaluated through measurements of the POS conduction time, POS voltage, and load current pulse shape. Asymmetry in the current distribution was found to degrade the performance of the switch but matching the asymmetry in current with an asymmetry in the plasma was found to restore the performance to the level seen with symmetric current injection. An asymmetry in the plasma distribution with symmetric current injection was found to have little effect on the peak generated POS voltage, but was found to degrade the initial rate of current transfer to the load.