Modelling study of dielectric barrier glow discharge in Ar/NH₃ mixture at atmospheric pressure

In order to investigate the mechanism of dielectric barrier glow discharge in Ar/NH₃ mixture at atmospheric pressure, a multiple particles self-consistent coupled fluid model is proposed. And the finite-element method is used in the numerical calculation model, so the periodically varying waveforms of gas voltage, dielectric surface charge density and discharge current density are investigated. The spatial and temporal distributions of charged and neutral particles density and space electrical field strength are also obtained. The simulation results show that the periodic breakdown process of the gas gap is controlled by the gas voltage, and affected by dielectric surface charges. The spatiotemporal distributions of charged particle density and electrical field strength show that the discharge under conditions considered in this model is a typical atmospheric pressure glow discharge, and that in the discharge process there exist an obvious cathode fall region, a negative glow region, a Faraday dark space, and a positive column region. In the Ar/NH₃ plasma, the dominant positive ions are NH₃⁺, and the next ions are Ar₂⁺; the dominant negative ions are NH₂^-; the main radical molecule products of ammonia decomposition are NH, NH₂, and N₂H₃, but the main final stable products are N₂ and H₂.