Modeling of Positive Leader Speed Under Slow Front Voltages—Part I: Long Air Gaps

This paper introduces a new mathematical model of positive leader propagation speed based on intense ionization in a thin boundary layer ahead of the tip of the leader channel. The model explicitly accounts for the effect of overvoltage and the resulting increase in leader current on leader speed. The model was applied to large rod-plane gaps under critical switching impulses. Numerical assessment of the model findings is included and whenever possible comparison with experiments has been found satisfactory.