Glow currents in a point-to-plane dielectric barrier discharge in the context of the chemical reactivity control

Abstract

This paper reports on the identification of the glow current components also called pseudo-continuous components associated to non-impulsive currents, in a point-to-plane dielectric barrier discharge (DBD) energized by a sinusoidal alternating high voltage. Thanks to a detailed analysis of both photographic and discharge current recordings, coupled to a close comparison with dc corona behaviours, the existence of both positive and negative glow discharges in DBDs is evidenced. The negative glow current can represent the major part of the current in the negative alternation. The relatively low amplitudes of the glow currents (∼0.1–1 mA), compared to streamers pulses amplitudes, often make them quite difficult to detect although they often represent more than 50% of the power delivered to the discharge cell. Discharge photographs taken with a fast camera demonstrate that the negative glow (in the negative alternation of the voltage) can, for high voltage levels, extend across the whole gaseous gap with higher current amplitudes than in dc coronas and without any spark breakdown risks. Thus, the ionization and thermal phenomena identified under negative dc corona may play a more important role in the DBD chemical reactivity, besides the streamer type discharges, in particular through their influence on the gas temperature and chemical species profiles in and out of the discharge volume; this last point is evoked in the discussion closing the paper.