Probability-statistical model of a liquid dielectric conductivity

The electrode surface is usually supposed to be ideally smooth when current passage is considered. However it is known that any real surface is rough to some extent. Even a smoothly polished surface (e.g. of a metal electrode) is covered by microprojections, the dimensions of which have the order of magnitude -10^-6 m, and a surface density N~10¹² m^-2. Their electric field strength is 2-3 orders higher then the average value near the electrode surface. When E⩾1 kV/cm, in the neighborhood of roughness there are favorable conditions and the layer, directly adjoining to the electrode surface and having a thickness of order of average size of microprojections (h⩾10^-6 m), is conducting. The considered process stages (breakdown, electrization) being underdeveloped and roughness size being small, smoothing out takes place. In the opposite case interfilm flows along the electrodes or the flows as narrow jets normal to the electrode surface can arise. On more coarse surfaces the charged layer thickness can reach values comparable with those of hydrodynamic layers, leading to macroscopic EHD-phenomena and their contribution to the electric current through the dielectric liquid. This theoretical investigation is undertaken with a goal to base the principal possibility of describing laws of the electric current passage in liquid dielectrics on the basis of accounting electrode roughness