CHARGING AND FLASHOVER INDUCED BY SURFACE POLARIZATION RELAXATION PROCESS

Electric charges trapping into a dielectric medium are described from polarons trapped into sites which are characteristic of the material structure (polaron trap). In terms of susceptibility, that means charges are trapped into sites whose susceptibility is lower than their surrounding environment. The charge trapping produces polarization of the medium. The energy of polarization per embedded charge is estimated to be equal to 5-chi (chi being the susceptibility). The surface breakdown of the dielectric is attributed both to charge detrapping and to relaxation of energy of polarization, using the collective many-body process. The consequences of this interpretation are consistent with experiments on surface breakdown performed with a scanning electron microscope. Furthermore, considerations about the improvement of breakdown voltage for dielectric materials are introduced.