Corona Discharge to Water Surface and Its Transition to a Spark

Impulse corona discharge in atmospheric air to the surface of a water layer with different electric conductivities is studied. The discharge was initiated from a corona electrode consisting of a metallic disk with evenly distributed corona needles. The dependences of the magnitudes of the measured impulse currents on the polarity of the corona electrode as well as the parameters of the gas gap and liquid layer were obtained. An equivalent electric circuit of the discharge system was proposed, allowing for explanations of the regularities in the measured currents and also the role of the water layer as a factor affecting the transition of the corona discharge to a spark.