Measurements of electric current through a liquid-air interface in corona discharge

Corona discharge from a point provides an ion source and can induce electrohydrodynamic (EHD) instabilities on layers of dielectric liquids. A first instability is associated with the classical EHD instability of a layer of insulating liquid subjected to unipolar injection. A second instability, referred to as rose-window, is characterized by larger cells and appears also in ohmic liquids. The electric current through the liquid is an important variable in the study of the instabilities that appear on the layer. We have measured the electric current for different liquids, as a function of the thickness of the layer, the height of the point, and the imposed voltage.