Selection of dielectric material for producing diffuse dielectric barrier discharge plasma at atmospheric pressure

Abstract

Abstract We report the effect of dielectric layer and its selection criterion to produce diffuse dielectric barrier discharge plasma at atmospheric pressure. The dielectric barriers over electrodes are used to prevent glow-to-arc transition by limiting growth of discharge current. We have analyzed the dielectric properties such as secondary electron emission, dielectric constant, dielectric thickness etc in order to get better power efficiency at breakdown. It is observed that a thin dielectric layer with high dielectric constant is suitable for lowering the breakdown voltage. During one of our experiments, planar-surface discharge plasma was produced with the use of epoxy resin dielectric-covered stripe electrodes. High-voltage high frequency signal was applied between the electrodes to produce the discharge. It is observed that the discharge remain stable & uniform in our parametric range. However, after prolonged discharge operation, degradation of dielectric layer was observed in the form of powder formation over the dielectric insulation. SEM analysis reveals that the powder contains individual as well as cluster of particles of micrometer size dimension. Such micro-particle formation may be useful for some material and biomedical applications, however in other way degraded dielectric would lead to spark formation in plasma. In this context, theoretical and experimental analysis of our results is presented in this paper.