Effects of plasma surface layers on the efficiency of plasma flow switching

The plasma flow switch is a possible fast opening-switch for Z-pinches on inductive-store pulsed-power machines. This paper presents results of two-dimensional, radiation-magnetohydrodynamic models for a well-characterized plasma flow switch operating into a load region at current levels of 5-6 MA. The calculations predict that motion of the switch plasma along coaxial electrodes leads to the formation along the inner electrode of a boundary layer that can interfere with switching. The simulations describe the effect of the boundary layer on switching and show that it may be removed by means of a boundary-layer trap. Predictive calculations were used to eliminate the effects of the boundary layer and led to an improvement in the switch´s performance. Comparison with experiments lends credence to the model