INFLUENCE OF HUMIDITY ON CURRENT WAVE-FORM AND LIGHT-EMISSION OF A LOW-FREQUENCY DISCHARGE CONTROLLED BY A DIELECTRIC BARRIER

The aim of this work is to determine the effect of humidity on a silen t discharge in air. A point to plane configuration has been used. Curr ent and emission spectra of the discharge have been recorded in dry an d humid air for short and long inter-electrode gaps and with the plane electrode coated by a silicone rubber plate alone or under a polyprop ylene film. Results show the typical corona discharge regimes. For a l ong gap, humidity decreases the number of breakdown streamer pulses. F or a short gap, the behavior observed depends on the surface conductio n of the dielectric in contact with the discharge. These results show that the presence of humidity in the discharge cell not only modifies the gas but also the surface states of the dielectrics coating the ele ctrodes. The surface charge decay appears as a major parameter, since it is related to the local field value which results from the applied field and the reverse field induced by charge accumulation during prev ious discharges.