Gasdynamic Diode: How to Stop 100-kV Streamer

The results of a two-dimensional numerical simulation of a streamer discharge developing through a shock wave in air were presented for various neutral density discontinuities across the wave. The focus was on the case when the streamer propagated from a low-density region to a high-density region. Streamer characteristics changed greatly after intersecting the shock wave. It was shown that the streamer failed to penetrate into the high-density region when the ratio between the densities in these regions was sufficiently high (\textgreater 1.2). In this case, the discharge developed along the surface between these regions after reaching the boundary between them. Thus, the gaseous medium demonstrates a unidirectional conductivity on a short time scale; a gas density discontinuity forms a kind of ``gas-dynamic diode'' that allows the plasma channel to propagate in one direction and blocks its development in another. Streamers could penetrate into any of the high-density and low-density regions when a neutral particle density discontinuity was replaced by a gradual density change.