Chemical kinetics simulation for atmospheric pressure air plasmas in a streamer regime

We present a theoretical analysis of air discharges at high pressure which operates in a streamer regime. The aim is to provide a simplified framework to study the chemical kinetics in the discharge gas phase. We have tried to model the characteristics of actually existing devices, such as dc and ac discharges in sharp point-plane, point to point, or coaxial cylinder configuration, dielectric barrier discharges. Within such scheme it is possible to perform numerical simulations in order to predict the evolution of the gas-phase chemical composition. As a first application we have chosen to simulate the chemical kinetics induced in a single isolated streamer and the results of this approach are examined within this paper. In particular, we have studied the detailed temporal evolution of the discharge gas phase using reference values for the simulation free parameters. The interplay between different time scale processes is shown. The effect due to charged as well as metastable species on chemical kinetics has been discussed too. Then we have studied the dependence of chemical species density on discharge parameters such as the electron temperature, the electron density, the transverse radius of the streamer, and the streamer formation time. Many results can be proven relevant for a better understanding of the operating conditions during technological sensible processing based on atmospheric pressure plasma. (C) 2005 American Institute of Physics.