Electrical discharge initiation and a macroscopic model for formative time lags

Formative times in electrical discharges in overvoltaged gaps are analyzed with a model having no spatial dependence and with simple assumptions about discharge channel temperature T and discharge voltage. The model treats the early temporal evolution of the discharge. Specifically, the dissipative voltage drop, V*, across the discharge is taken to be a step function of T. Thermal quasi-equilibrium is assumed in the discharge medium, and it is shown that d(In t/sub d/)//sub d/(In theta )=-1, i.e., theta t/sub d/=constant, where theta is the fractional overvoltage and t/sub d/ is the formative time lag, in agreement with measured values of t/sub d/ for much of the experimentally explored range of theta . Highly-time-resolved ( approximately 92 ps) experimental data are presented for the first 10 ns of electrical discharge initiation; these data suggest that the authors' model should provide a reasonable representation of t/sub d/ when t/sub d/>10-100 ns.<
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