Non-local effects in spatial distribution of excitation rates in positive column of glow discharge plasma of molecular gases

Research output

Abstract

At simulations of gas-discharge plasmas the electron distribution function (EDF) is usually calculated using a local approximation (LA) which is applicable only when electron energy relaxation length \textit{le} $<\quad R --$plasma size. For atomic gases \textit{le} $> \quad 100l$ ($l$ -- electron free-path-length), so the LA for EDF is not valid up to high pressures. By contrast, in molecular gases due to strong vibrational excitation with low energy threshold, the length \textit{le} is small \textit{le$\sim$l}. And so it is assumed everywhere that the LA for EDF calculation in molecular gases is valid in any cases when diffusive approximation $R$>$l$ is applicable. In this report it is shown that in molecular gases local approximation is inapplicable on the discharge periphery, where ambipolar field exceeds longitudinal field. A heating of fast electrons in ambipolar field gives rise to excitation constants from centre to periphery of discharge.
Original language Undefined 53 Bulletin of the American Physical Society 53 10 Published - 2008