Lightning corona sheath dynamics based on a generalized space charge distribution

摘要

A model of corona sheath that surrounds the thin core of the lightning channel has been investigated by using a new space charge function. The lightning channel is modeled by a charged corona sheath that stretches around a highly conductive central core through which the main current flows. The channel core with the negatively charged outer channel sheath forms a strong electric field, with an overall radial orientation. The return stroke process is modeled as the negative leader charge in the corona sheath being discharged by the positive charge coming from the channel core. The corona sheath model [1-5] divides the sheath into two zones with charges: zone 1 (surrounding the channel core with net positive charge) and zone 2 (surrounding zone 1 with negative charge). We introduced a new expression for space charge distribution inside both zones that represents a generalization of previously used space charges. Using appropriate parameter values, previously examined corona charge densities are obtained as special cases of this generalized distribution. Furthermore, the influence of the new distribution of space charge on the corona sheath dynamics is examined. Expressions that describe how the corona sheath radius evolves during the return stroke are obtained from the adopted corona sheath model and the new sheath space charge density. The new distribution can also be readily applied to transmission-line type models.