The sensitivity of sprite streamer inception on the initial electron‐ion patch

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Sprite streamers are bright atmospheric phenomena above thunderstorms powered by sufficiently high electric fields and free charges from inhomogeneities in the mesosphere or ionosphere. A common feature of recent simulations is that they model the streamer inception from spherical Gaussian electron‐ion patches. We here tackle the question: How do the streamer inception time and streamer properties depend on the initial geometry? Therefore, we consider prolate (“cigar”) and oblate (“pancake”) electron‐ion patches aiming to understand the geometric influence on streamer inception speed, electric field evolution, branching time, and ohmic heating of streamers. We initiate patches of different geometry with fixed peak densities of 5·1011 m−3 or with a fixed total electron number of 9.40·1012 in ambient fields of 0.5 and 1.5 times the breakdown field and study the streamer evolution between 60 and 80 km altitude with a 2.5D cylindrical Monte Carlo particle code. We present the evolution of the electron density and of the electric field. In our simulations, the time for the electric field tips to develop into the regime where they can self sustain the discharge is shortest for streamers from prolate patches and longest for oblate patches. The branching time of negative fronts depends on the eccentricity and increases for oblate patches ranging from 5 μs to 8 μs. We observe ohmic heating with maximum temperature differences up to tens of K depending on the eccentricity and density of the initial patch influencing the efficiency of plasma reactions in streamer channels.
Original languageEnglish
JournalJournal of Geophysical Research: Space Physics
Volume124
Issue number4
Pages (from-to)3083-3099
ISSN2169-9380
DOIs
Publication statusPublished - 2019
CitationsWeb of Science® Times Cited: No match on DOI

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