Electron Scattering and Hydronamic Effects in Ionized Gases

Abstract

Intensive effort to understand the complex phenomenology of propagation and dispersion of shock wave in weakly ionized medium has been initiated recently, in view of the prospect for wide range of applications that could follow. Underlying mechanisms for the observed effects could be attributed to various electron collision processes. Although most applications involve molecular gases, the dispersion effects with a comparable intensity are observed in noble gases. Interaction of shock wave with ionized gas generates rapidly moving multiple electric layers, which form regions of increased electron density. Transient electric field in the electric layers enables new channels of communication between upstream and downstream regions. Time scale of collective interactions is comparable to the electron collision time and lifetime of excited states. In this environment electron scattering with excited atoms affects the macroscopic phenomenology as much as the transient field affects the collision itself. This results in an intricate ionization and recombination dynamics where the electron scattering with excited states is among the most important processes.