Two-dimensional simulation of filaments in barrier discharges

We present a fluid model for barrier discharges in air at atmospheric pressure with spectral resolved photonic secondary processes, implemented with general finite-element software. The results show five different discharge phases, a homogenous and a space-charge dominated avalanche phase, a phase of dielectric charging with field enhancement due to positive ions causing streamer formation, a cathode streamer and a subsequent glow-discharge phase with a cathode-fall region. Quenching of the microdischarge occurs after a few nanoseconds by the increasing charge on the dielectric. While the capacity of the dielectric has nearly no influence on the energetic efficiency of radical production and vacuum-UV-irradiation of the dielectric, a higher voltage causes a small decrease in radical efficiency and a significant increase in the efficiency of VUV-irradiation of the dielectric. (author)