Pre-breakdown luminous wave in coplanar barrier discharge

In physics of dielectric barrier discharges two consecutive phases of discharge dynamics were reported so far. The Townsend phase of discharge formation followed by the ionizing waves propagation (cathode/anode). During the Townsend phase the formation of electron avalanches leads to space charge accumulation and electric field distortion invoking the propagation of ionizing waves leaving the dielectrics charged by surface charges. In present contribution the new luminous phase of discharge formation is reported in coplanar dielectric barrier discharge, that precedes the Townsend phase of discharge formation. During this phase the luminous cloud was formed above the edge of still negative electrode, just before the change of electrodes polarity. Consequentlyit spread across the whole electrode surface as a luminous wave. This extremely weak light phenomenon was attributed to surface charge dynamics connected to the recombination of surface charges prior to the next discharge event.