Spectroscopic Study of Ar-N2 Spatial Postdischarges Sustained in Atmospheric-Pressure Microwave Plasmas

Abstract

Atmospheric pressure microwave-sustained Ar-N2 spatial postdischarges are characterized by a high content of reactive nitrogen species as well as low gas temperature values with potential to be used in different applications, including the treatment of the surface of thermosensitive materials. However, optimizing their performance requires prior knowledge of their composition, as well as of the kinetics involved in their sustainment. A comprehensive experimental characterization of Ar-N2 spatial postdischarges generated with different nitrogen concentrations by optical emission spectroscopy has been performed, together with direct gas temperature measurements. From this study, a complete postdischarge kinetics scheme is proposed for the first time for this kind of spatial afterglows, highlighting the crucial role of argon and nitrogen metastables.