Simulation of breakdown in air using cellular automata with streamer to leader transition

We propose a new discrete stochastic model for computer simulation of the l ightning process and the breakdown process in long gaps in gaseous dielectr ics, In this model we used cellular automata, Two different states of a con ductive structure that correspond to streamers and channels of very high co nductivity (leader phase) are introduced. The conductivity of the streamers is assumed to be negligible in comparison with highly conductive channels. The electric-field potential is obtained by solving the Laplace equation i n a region outside the equipotential, highly conductive part of the structu re, As the streamer growth criteria we use two multi-element models in whic h several conductive bonds can arise at each time step. The growth is stoch astic in time, and the probability of streamer formation is proportional to a certain function of local electric field r(E) that depends on the proper ties of the dielectric. If the energy released in a segment of the streamer is larger than a certain critical value, the streamer transforms to a high ly conductive phase. Patterns of conductive trees are obtained in computer simulations of breakdown under various conditions.