Two-dimensional studies of current conduction in plasma opening switches

We summarize our general understanding of the long conduction time (~1 μs) plasma opening switch POS, both in the conduction phase and in the opening phase of POS operation. For long conduction times, the mechanisms dominant in conduction have origins in electron-Hall effect (EHD) and in magnetohydrodynamics (MHD). These mechanisms are considered in the context of experiments conducted on two different pulsed power accelerators, with concurrent in situ measurements, of plasma density indicating that one of the accelerators is predominantly in the EHD, the other in the MHD regime. In the latter case, with application of a 2-D snowplow model we are able to reproduce with fair accuracy the time variations of line integrated plasma density observed with laser interferometry near the cathode. For the opening phase, we introduce a theory of magnetically enhanced ion erosion for plasma sheath formation and development of switch voltage. The theory, based on conservation of total momentum flux in the sheath, electromagnetic as well as particle, captures the measured voltage saturation of the switch limited POS operation.