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 discharge). The aim of this paper is to contribute to a better understanding of the transition from a glow silent discharge to micro-discharges in nitrogen at atmospheric pressure. For this purpose, the two types of regime have been studied by emission spectroscopy and electrical measurements. The transition is always observed due to an increase of the power dissipated in the 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 the gas. These results have been explained by the predominance of the density of metastable nitrogen molecules on the discharge regime. Due to the creation of seed electrons via Penning ionization, these metastable molecules can control the gas breakdown and so the discharge regime. Their density essentially depends on their quenching rate. The products etched from the surfaces in contact with the discharge appear to be the main source of the metastable molecules quenching. Therefore, the nature of the surface controls the nature of the quenching of the metastable molecules and the power dissipated in the discharge the quencher density.