Collective acceleration of streamer discharge systems

Abstract:

The early development of a lightning discharge is often observed to involve the rapid motion of a discharge structure, known as fast breakdown (positive and negative). One hypothesis to explain this emission is that it is produced by a moving population of streamers, millimeter-scale cold plasma discharges that can extend, branch, and interact as they extend over meter scales. However, the collective dynamics of such large-scale streamer systems is quite complex, thanks to interactions between streamers and their effects on the external electric field that drives the discharge. These collective effects can be studied by simulations including streamer-streamer interactions and charge flow along the network of channels left behind. Running such simulations with populations of thousands of streamers on meter scales captures many interesting collective effects, including a population of streamers lagging behind the main population, extensive interconnection between channels, and the formation of local hot-spots within the channel network. One especially intriguing result is the collective motion of the population of streamers and how the interactions between streamers leads to an acceleration of the propagation of the overall system at speeds several times greater than those expected for the propagation of isolated individual streamers. This acceleration may help provide an explanation for the "fast" nature of fast breakdown.