Double Layer Effects on Shock Wave Propagation

An analysis and assessment of two mechanisms in plasma shock interactions was conducted under conditions typically encountered in a weakly ionized glow discharge. The mechanisms of a spatially-dependent electron temperature and additional electron impact ionization at the shock front were examined for effects on shock structure and propagation. These mechanisms were incorporated into an existing one-dimensional, time-dependent, fluid dynamics code that uses the Riemami problem as a basis and numerically solves the Euler equations for two fluids: the neutral gas and the charged component. The spatial variation in electron temperature was modeled as a shock-centered rise in temperature. Additional ionization was modeled by incorporating a variable electron temperature and a quasi-kinetic collision function, for both unrestricted ionization and ionization mitigated by ion-electron recombination. Introduction of a spatial variation in electron temperature resulted in a broadening and strengthening of the electric field associated with the electronic double layer (EDL) at the shock front. Results of unrestricted ionization were a broadening and strengthening of the electric field associated with the EDL, acceleration of the neutral shock front, and the development of a neutral precursor ahead of the shock. Ion-electron recombination was seen to reduce these effects