Breakdown of air over a water surface stressed by a perpendicular alternating electric field, in the presence of a dielectric barrier

Distortion of the surface of a water layer serving as the ground electrode of an experimental ozone generator has a strong influence on the generator´s performance. The distortion is highly affected by the frequency, as well as the magnitude, of the applied electric field. In turn, the resultant field is affected by the distortion. Over the frequency range tested (20-300 Hz), the applied field required to initiate electrical breakdown of the air over the water surface was found to be less than that required for breakdown over a flat metallic electrode. This reduction in applied field for breakdown is attributed to a reduction of the air-gap height due to an upward bulge of the water surface, and to field intensification by sharply pointed cones. The cones are most predominant at lower frequencies