Dynamic modelling of lightning return stroke and its optical and electromagnetic radiations based on Maxwell´S integral-equations

A lightning return stroke is always preceded by a downward leader process that takes a dominant role in determining the property of the return stroke. Besides, the channel parameters of a return stroke are spatial and temporal variables. These two points are ignored or scorned in most of existing return stroke modelling. In this research, we have developed a leader-return stroke coupled model based on the time domain electric field integral equation (TD-EFIE), which is actually a growth of Kumar´s microscopic model. With a presumed leader channel and boundary condition, a set of equations controlling the evolutions of return stroke parameters, such as the channel current, channel charge deposit, channel radius and conductance, is derived. Furthermore, based on the channel current and conductance, a set of equations for calculating the current-produced electromagnetic fields and light emissions is also derived. A trial of the present model yielded preferable results on both the return stroke current and its optical and electromagnetic radiations in comparison with those observations in literature.