Extension of lightning corona sheath model during return stroke

A generalized lightning traveling current source return stroke model has been used to examine the characteristics of the lightning channel corona sheath. A model of lightning channel consisting of a charged corona sheath and a narrow, high conducting central core is assumed. The return stroke process is modeled with the positive charge coming from the channel core discharging the negative leader charge in the corona sheath. According to the corona sheath model proposed earlier by Maslowski and Rakov, it consists of three zones, zone 1 (inner zone containing net positive charge), zone 2 (surrounding zone 1 with negative charge and outer zone 3 without charge. We adopted the assumption of a constant electric field inside zone 1 of the corona sheath proved in the experimental research of the corona discharges in a coaxial geometry of Cooray. This assumption seems to be more realistic than the assumption of a uniform corona space charge density used previously in the study of Maslowski and Rakov, Marjanovic and Cvetic, and Tausanovic et al. Based on the measurements of the electric field performed by Miki et al, the conductivity of the channel sheath in zone 1 is calculated.