Exploring the mechanisms leading to diffuse and filamentary modes in dielectric barrier discharges in N 2 with N 2 O admixtures

Abstract

Abstract: The effects of nitrous oxide (N2O) in nitrogen (N2) on the development and morphology of sine-driven dielectric barrier discharges in a single-filament arrangement were studied. Detailed insight in the characteristics of the discharge and its development were obtained from electrical measurements combined with ICCD and streak camera recordings as well as numerical modelling. A miniaturised atmospheric pressure Townsend discharge (APTD) could be generated for admixtures up to 5 vol% N2O in N2 although N2O is an efficient collisional quencher of metastable nitrogen molecules. Increasing the high voltage amplitude led to a transition into a hybrid mode with the generation of an intermediate filament in addition to the diffuse, non-constricted APTD. A time-dependent, spatially one-dimensional fluid model was applied in order to study the underlying mechanisms causing the diffuse discharge characteristics. It was found that even for small N2O admixtures, the associative ionisation of atomic nitrogen and oxygen (O + N(2P) → NO+ + e) is the major electron source sustaining the volume memory effect and is therefore the reason for the formation of a diffuse APTD. Graphical abstract: [Figure not available: see fulltext.].