Investigations of positive streamers as quasi-steady structures using reduced order models

Single streamers are currently well simulated using detailed computational models. Most of these models are inhibitively complex to use for modelling many-streamer interactions in a streamer corona. This work develops reduced order models of single positive streamers in atmospheric pressure air that replicate the core macroscopic behaviour of detailed models while using a simpler physics representation. Models are developed using the 1.5D framework, with emphasis placed on solving the equations of motion in the streamer reference frame. The solution in this quasi-steady frame is shown to be a good representation of the instantaneous state of the streamer. Finally, a method of uniquely characterizing the instantaneous state of a streamer using its macroscopic parameters (velocity, radius, tip electric field and channel electric field) is developed. This characterization is interpreted graphically, with streamers treated as quasi-steady structures which evolve in time at a rate much slower than the time scale of electron transport. Previous work in the literature is shown to be well captured by this interpretation.