BREAKDOWN PROPERTIES OF RANDOM-SYSTEMS WITH DISTRIBUTED CONDUCTANCES

The breakdown problem in a random system is investigated by numerical simulation for a network of distributed conductance The breakdown voltages are studied in the different conductance configurations. The mean breakdown strength shows anomalous size dependence given by < V(b) > proportional-to 1/((ln L))y for L (the linear dimension of the network). The exponent y depends upon a degree of non-uniformity of the system and gives an information on the critical event of the breakdown. For the case of a comparatively homogeneous network the micro-crack nucleation is the critical event of a breakdown. In such a random resistor network funnel defects act as the appropriate critical defects. On the other hand, in the case of strongly disordered system the critical event in a breakdown is attributed to growth of cracks.