Fluid modeling of surface dielectric barrier discharges to understand bulk and surface phenomena*

Surface dielectric barrier discharges (DBDs) in ambient air have found applications in agriculture for plasma treatment of water, as well as pollution control. One of the key aspects that is not well understood in surface DBDs is the influence of the operational parameters such as power, applied voltage, and relative humidity for discharge operation and for effective dissociation of molecular species. Recent experimental investigations have shown that plasma ignition is inhibited at high relative humidity. However, difficulties arise for in-situ diagnosing of discharge parameters in close proximity to the surface. In this work, a 2-D fluid model for surface DBD is developed to complement experimental measurements and assess the influence of volume and surface processes for discharge formation. The model couples fluid discharge equations for a four fluid mixture including neutrals, electrons, positive ions, and negative ions, with the Poisson equation. As a result of the model, the coupling of bulk and surface processes and the effect of air humidity on discharge parameters is investigated. The understanding of transport and heterogeneous processes at the plasma-surface interface plays an important role for improvement of current 0-D plasma models with detailed chemistry.