Effects produced in dielectric barrier discharges by dielectric structures not in contact with plasma: 2D modeling approach

Abstract

The paper presents results of a computational study of the effects of different catalytic structures on the plasma parameters in dielectric barrier discharge (DBD) reactors. The catalytic structures, rods and voids with spherical and ellipsoidal cross sections having different orientations, are embedded into the bottom dielectric of a DBD reactor and are not in contact with plasmas. These structures enhance or deplete the electric field due to their polarization by approaching DBD surface streamers. The electric field enhancement in such structured DBDs depends upon the geometrical layout and the dielectric constant of the structures. The mode of plasma propagation is also sensitive to the shape and orientation of the rods and voids. It is found that the embedded material with higher dielectric constant produces more intense enhancement or depletion of plasma density in vicinity of rods or voids, respectively. It is shown that, in the considered arrangement, the rods mainly serve as catalysts while voids act as inhibitors for plasma processing. The electric field enhancement results in increasing fluxes of reactive species toward the surface where the catalytic structure is located. It is shown that by producing the designed combinations of rods and voids, one can control the production of useful species in the gas phase and, as a result, the production of fluxes of useful species to surfaces.