Imaging and reconstruction of positive streamer discharge tree structures

Streamer discharges often exhibit branching, which can greatly affect their behavior and will lead to so-called streamer trees. In this work we present a methodology for investigating the structure of a streamer discharge tree by means of advanced imaging techniques. Stereoscopic and stroboscopic techniques augment the images with depth perception and temporal information relevant to study the inherently stochastic three-dimensional and transient streamers. A semi-automated post processing algorithm is developed to make a reconstruction of the streamer discharge tree formation. This results in a tree of streamer segments, separated by branching events, where velocities, diameters and trajectories are used to characterize the morphology. The workings of the algorithm is detailed using an exemplar measurement series of positive streamers in synthetic air at 233 mbar.