Streamer propagation as a pattern formation problem: Planar fronts

Streamers often constitute the first stage of dielectric breakdown in strong electric fields: a nonlinear ionization wave transforms a nonionized medium into a weakly ionized nonequilibrium plasma. New understanding of this old phenomenon can be gained through modern concepts of (interfacial) pattern formation. As a first step towards an effective interface description, we determine the front width, solve the selection problem for planar fronts, and calculate their properties. Our results are in good agreement with many features of recent three-dimensional numerical simulations.