Propagation Along a Cylindrical Model of the Lightning Return Stroke

The relationship between the current in the lightning strike and the radiated fields varies considerably by both the physical assumptions used and the approximate model chosen for the lightning channel. In this paper, we consider the lightning channel in two cylindrical regions -the conducting channel and the region outside the channel. Most of the lightning literature uses various departures from a transmission-line model to predict the current evolution. We use the two region plasma model in the frequency domain and estimate the radial field distribution with solutions to Bessel's equation and solve for the propagation constant in the usual way. We find that the high frequency components of the current in the channel are attenuated as they propagate upward implying that the high frequency fields are generated from currents near the surface.