Chemical composition of gaseous products generated by coplanar barrier discharge in air and N₂/O₂ mixtures

Abstract Absolute densities of gaseous products generated by coplanar dielectric barrier discharge in N2/O2 mixtures and in ambient air were determined using Fourier transform infrared (FTIR) spectroscopy. A theoretical model containing up to four molecular absorption cross sections was used to split the peaks overlapping in the FTIR spectra. The product densities were determined for a wide range of applied input powers (100 - 400 W). Ozone (O3) and nitrogen oxides (N2O, NO, NO2 and N2O5) were identified as the stable products of the discharge in N2/O2 mixtures, HNO2, HNO3 and CO2 were steadily present in the gas coming from the discharge in ambient air. It was found that the actual product composition strongly depends on the gas temperature. At low input power with the low gas temperature, (O3 density was high and the NO and NO2 densities were very low. At a specific input power (and the gas temperature) O3 disappeared, while NO density started to increase gradually and NO2 density increased steeply. N2O5 density increased at low input power but decreased suddenly at the same temperature when O3 density decreased. The influence of the gas temperature on the discharge product composition was also confirmed by the 0D chemical kinetic model and by temperature measurement. The maximal ozone density reached approximately 2.7 × 1023 m-3 for the input power below 150 W and the gas mixture N2:O2 40:60. Density of 2.6 × 1022 m-3 was obtained for NO2 in the same gas mixture above 250 W.