Modelling of streamer discharges between insulating and conducting surfaces

Two types of discharge configurations are discussed: (1) small spherical voids embedded in a dielectric (small cavities with one metal electrode) which both have in common that the radial spread of a surface discharge is negligible; (2) oblate inclusions embedded in a dielectric or with one metal and dielectric boundary. In these cases a radial surface discharge propagation (perpendicular to the electric field) predominantly determines the discharge process. The authors present a simplified physical model for partial discharge quantities based on the streamer theory serving to analytically estimate, for example, apparent charge, pulse phase/pulse height distribution, inception voltage for the two cases mentioned.