Transition from glow silent discharge to micro-discharges in nitrogen gas

At atmospheric pressure, the electrical breakdown of a silent discharge can occur in many thin filaments (leading to micro-discharges) or in a single discharge canal covering the entire electrode surface (leading to a glow di scharge). The aim of this paper is to contribute to a better understanding of the transition from a glow silent discharge to micro-discharges in nitro gen at atmospheric pressure. For this purpose, the two types of regime have been studied by emission spectroscopy and electrical measurements. The tra nsition is always observed due to an increase of the power dissipated in th e gas gap, but the maximum power that can be used while maintaining a glow discharge depends on the nature of the dielectric surface in contact with t he gas. These results have been explained by the predominance of the densit y of metastable nitrogen molecules on the discharge regime. Due to the crea tion of seed electrons via Penning ionization, these metastable molecules c an control the gas breakdown and so the discharge regime. Their density ess entially depends on their quenching rate. The products etched from the surf aces in contact with the discharge appear to be the main source of the meta stable molecules quenching. Therefore, the nature of the surface controls t he nature of the quenching of the metastable molecules and the power dissip ated in the discharge the quencher density.