EXPERIMENTAL INVESTIGATION OF THE CURRENT IN A MICROSECOND-RANGE PLASMA EROSION SWITCH

A planar version of a microsecond-range plasma erosion switch (PES) is investigated; the obtained results are described. The type of the PES operating mode is found to be determined by the initial plasma density. A low or high PES impedance corresponds to a high or low initial density, respectively. In this work, the PES impedance is called ''low'' (or ''high'') when it is lower (or higher) than the characteristic impedance of the induction or capacitance energy-storage system used. The diagnostics are comprised of ion probes and a high-speed framing-photography system viewing the interelectrode gap. The behavior of the planar PES operating in the high-impedance mode (i.e., when the initial density is low) is found to be qualitatively similar to that of the previously investigated coaxial PES. The experiments reveal that, for high-density (and low-impedance), the behavior of the PES is influenced by boundary effects; in addition, the development of a large-scale instability is observed to occur in the final stage of the current passage through the PES.