Plasma Dynamics in Opening Switches

The energy balance of a plasma opening switch in the conduction stage is calculated, in which the dominant process is magnetic field penetration into the plasma volume due to the magnetic piston effect. This mechanism is typical for a microsecond plasma opening switch of the mega-ampere range. It is also shown that the process of magnetic field penetration into the switch plasma is determined by the field diffusion near the magnetic piston, followed by the convective transport of magnetic field in the plasma. This transport is due to the field being frozen-in into the plasma flow behind the shock wavefront, which is formed in the plasma accelerated by the magnetic field pressure. The shock wave propagation leads to the formation of directed plasma flow with falling density, velocity, and pressure in the region between the magnetic piston and the shock wavefront. The following analysis of gas dynamics and related electromagnetic problems reveals the most important processes determining plasma and magnetic field dynamics.