Self-consistent modeling of in dielectric-barrier atmospheric plasmas

Summary form only given. Nonthermal dielectric barrier plasmas produced at atmospheric pressure have been studied extensively in terms of their current-voltage characteristics and optical emission. While there has been a great deal of progress towards development of their capability as a material processing tool, a full and quantitative understanding of their dynamic behaviour is still missing. This fundamental understanding is very important to underpin future development of dielectric barrier atmospheric plasmas, and will impact on development of suitable diagnostic methodologies and contribute to guidance for rig design and control. To a large extent, the current understanding of dielectric barrier atmospheric plasmas is based on a series of detailed numerical studies and typically these are based on the hydrodynamic assumption that electrons are in equilibrium with the local electric field. Both experimental evidence and comparison with glow discharges at intermediate pressures suggest that the hydrodynamic assumption may not valid in the electrode sheath region where electrons are yet to be sufficiently accelerated to reach equilibrium with the electric field. In this contribution we report results of a numerical study of dielectric barrier atmospheric plasmas based on a self-consistent model that removes the hydrodynamic assumption. Through numerical examples, it is shown that plasma dynamics in the sheath region are indeed very different when described with the self-consistent model. In general the hydrodynamic model overestimates ionization in the sheath particularly near the electrode surface. Yet it underestimates ionization around the boundary between the sheath and the plasma bulk region. Intriguingly these two shortcomings of the hydrodynamic mode compensate each other and for certain physical parameter its error is reduced. On the other hand significant drawbacks of the hydrodynamic mode are exposed clearly for other parameters such as spatial profile- of charged particles and excited species, electric field, and mean electron energy.