A diode laser study and modeling of NO and NO2 formation in a pulsed DC air discharge

The kinetics of a low pressure pulsed DC discharge in dry air is experimentally studied using simultaneous measurements of the concentrations of NO and NO2 downstream the plasma region. The measurements have been performed via infrared tunable diode laser absorption spectroscopy. The gas pressure was 3.95 mbar and the pulse duration and frequency range from 20 μs to 3 ms and from 50 to 1000 Hz, respectively. The peak current was varied from 10 to 80 mA. It is shown that the NO and NO2 densities depend only on the averaged current. In order to explain this feature a simplified analytical calculation has been developed which considers about 30 kinetic reactions involved in the NOx formation. The calculations lead to a fair agreement with the experimental results.