Dynamics of subnormal regime in a direct-current nitrogen micro-discharge

Abstract

The dynamics of a subnormal mode of direct-current micro-discharge in pressurized nitrogen is studied using a self-consistent one-dimensional plasma fluid model coupled with the compressible Navier-Stokes equations. To clarify different time scales, we use a hierarchy of plasma reaction mechanisms. The simplest mechanism considers the two-species plasma without any excited species. The excitation of electronic and vibrational levels of nitrogen is only considered in the electron energy balance. The second mechanism considers multiple ions and electronically excited species. The most comprehensive third mechanism expands the second mechanism by tracking the vibrationally excited species as well as the reactions of vibrational-translational and vibrational-vibrational relaxation. By using this third mechanism, we analyze the dynamics associated with the relaxation of the vibrational distribution function of nitrogen.