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Poster Session II

4:30 pm – 6:30 pm, Wednesday October 15 Session DW5 COEX, Lobby E
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Early Model of Lightning Spectrum Generation with PIC-DSMC

Poster 30
Presenter: Matthew M Hopkins (Sandia National Laboratories)
Authors: Nichelle Bennett (Sandia National Laboratories), Lucas Beving (Sandia National Laboratories), Dustin Fisher (Sandia National Laboratories), Max Flynn (Sandia National Laboratories), Christopher Hogg (Sandia National Laboratories), Christopher Moore (Sandia National Laboratories), Julia Tilles (Sandia National Laboratories), Lydia Wermer (Sandia National Laboratories)

Cloud-to-ground lightning strikes are generally a sequence of multiple steps of streamer-leader progression, including branching, followed by a strongly conducting arc once the strike has grounded. Different plasma chemistry is active in each of these different phases, and the spectrum generated by each of these phases is also different. This work begins an effort to produce a time history of spectra for a lightning strike from initial streamer-leader steps to final conducting channel, including continuing currents. To do so, a model of air breakdown mimicking lightning is first performed in an implicit PIC-MCC simulation code, Chicago. A time history of reduced plasma state (e.g., gas density, electron temperature, etc.) is extracted from the large-scale simulation and handed off to an explicit PIC-DSMC simulation code, Aleph, which is capable of directly tracking photons and large speciation sets. Aleph is then exercised in a 0D mode to achieve quasistatic plasma states and their associated spectra. Aleph will track molecular and atomic species of nitrogen and oxygen, including electronically and vibrationally excited states. Photonic chemistry is also included (e.g., photoionization). Differences in spectra from different stages of the lightning strike will be presented.

Funding acknowledgement

This work was supported by the Laboratory Directed Research and Development program at Sandia National Laboratories, a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc. for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.

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