Dynamics of the lightning channel using generalized traveling current source return stroke model

Characteristics of the lightning channel corona sheath surrounding a thin channel core are examined using the generalized lightning traveling current source (GTCS) return stroke model. The return stroke process is modeled with positive charge coming from the channel core discharging negative leader charge in the corona sheath. The corona sheath model that predicts charge motion in the sheath is used to derive sheath radius vs. time expressions during the return stroke. According to the corona sheath model, previously pro-posed in [1] and [2], it consists of two zones, zone 1 (surrounding the channel core with net positive charge) and zone 2 (surrounding zone 1 with negative charge). We adopted the assumption of a constant electric field inside zone 1 of the corona sheath observed in laboratory experimental research of corona discharges. We examined the influence of different magnitudes of the breakdown electric field at the boundaries of both zones on the dynamics of the return stroke. The new channel discharge function, calculated from the close electric field waveform measured at 15m from the channel [7], is used. The calculations have shown that the maximum radii of zones 1 and 2 significiaantly decrease compared to the previous results given in [9]. Similar conclusion holds for the velocities of zone 1 and 2 boundaries. It is concluded that the new channel discharge function gives the results for the time dependence of both the radii and their velocities in a good agreement with the theoretical predictions