We present a fluid model for barrier discharges in air at atmospheric press
ure with spectral resolved photonic secondary processes, implemented with g
eneral finite-element software. The results show five different discharge p
hases, a homogenous and a space-charge dominated avalanche phase, a phase o
f;dielectric charging with field enhancement due to positive ions causing s
treamer 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 capa
city 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 in
crease in the efficiency of VUV-irradiation of the dielectric.