Space charge distribution induced field strength size effect

The dependence of the breakdown field on the length of the dielectric gap of a parallel plate capacitor constitutes the field strength size effect. In the present interpretation of the size effect, the formation of a space charge is considered as the cause of breakdown, the energy source of which being supplied by the relaxation of the polarised lattice, subsequent to charge detrapping. Here we are considering breakdown at the anode where a stable glow is observed when the electric field becomes high enough, whose brightness increases with the field until breakdown occurs. This type of breakdown is observed when the internal field becomes greater than a threshold detrapping field, so that charges are successively trapped and detrapped during their flowing through the dielectric gap. Breakdown is triggered when critical conditions are reached, resulting from a balance between the energy released by detrapping and the dissipation of energy by the medium