High current surface discharge propagation analysis Application to the lightning leader

The main results obtained from a long-term experimental study of the mechanisms related to the propagation of gliding discharges are reported. The dominant role of the region of the discharge where the ionized medium changes from glow to arc is emphasized, along with the similarities of this discharge to a lightning stroke. The thermalized arc channel is found to be produced in three stages. The first stage features a preliminary discharge, similar to a positive glow, whose electron temperature is much greater than the gas temperature. There follows a transient arc stage with a constant duration of about 10 ns, where the major part of the energy of the electric field is transformed into ionization energy of the gas. Finally, there occurs the heating stage, with a duration between 25 and 60 ns, where the electric field is largely reduced and the ionization energy is partly in the form of heated neutrals.