  Previous studies of streamer discharge branching mechanisms have mainly been
generative other than predictive. To predict or even control branching, a
reliable connection between experimental conditions and streamer branching
needs to be established. As an important step toward the goal, in this work, a
2D deterministic model of negative streamers in air is numerically solved with
the ionization seeds assumed as the superposition of Gaussians. The "indicative
profiles approach" developed here can consistently relate the change in a
quantitative measure of geometrical irregularity of the seed profiles with
specific electron densities to the emergence of front splitting of streamer
discharges under various voltages, seed characteristic sizes, and preionization
levels. The results of this study could inform experiments to identify and
clarify streamer branching mechanisms.
