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Elongation and branching of stem channels produced by positive streamers in long air gaps

The elongation and branching of long positive spark discharges in the laboratory and in lightning have been attributed to the formation of thermalized channels inside a diffuse, glow-like streamer section at the leader head. It is experimentally shown here that the structured morphology of streamers...

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Autores principales: Zhao, Xiangen, Becerra, Marley, Yang, Yongchao, He, Junjia
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group UK 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7892885/
https://www.ncbi.nlm.nih.gov/pubmed/33603104
http://dx.doi.org/10.1038/s41598-021-83816-7
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author Zhao, Xiangen
Becerra, Marley
Yang, Yongchao
He, Junjia
author_facet Zhao, Xiangen
Becerra, Marley
Yang, Yongchao
He, Junjia
author_sort Zhao, Xiangen
collection PubMed
description The elongation and branching of long positive spark discharges in the laboratory and in lightning have been attributed to the formation of thermalized channels inside a diffuse, glow-like streamer section at the leader head. It is experimentally shown here that the structured morphology of streamers produce low-density stem channels that elongate and branch well before a new leader channel section is formed. These non-thermalized stems are also shown to develop ahead of a developing leader channel. These findings are based on high-speed photography and Schlieren imaging used to visualize both the morphology of streamer filaments and stem channels. Numerical analysis is also performed to estimate the axial temperature and density of the stem channels. A stem-driven mechanism for the propagation and branching of positive long air gap discharges is proposed and discussed based on the presence of not-yet thermalized, low density channels formed by streamer ensembles at the leader head.
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spelling pubmed-78928852021-02-23 Elongation and branching of stem channels produced by positive streamers in long air gaps Zhao, Xiangen Becerra, Marley Yang, Yongchao He, Junjia Sci Rep Article The elongation and branching of long positive spark discharges in the laboratory and in lightning have been attributed to the formation of thermalized channels inside a diffuse, glow-like streamer section at the leader head. It is experimentally shown here that the structured morphology of streamers produce low-density stem channels that elongate and branch well before a new leader channel section is formed. These non-thermalized stems are also shown to develop ahead of a developing leader channel. These findings are based on high-speed photography and Schlieren imaging used to visualize both the morphology of streamer filaments and stem channels. Numerical analysis is also performed to estimate the axial temperature and density of the stem channels. A stem-driven mechanism for the propagation and branching of positive long air gap discharges is proposed and discussed based on the presence of not-yet thermalized, low density channels formed by streamer ensembles at the leader head. Nature Publishing Group UK 2021-02-18 /pmc/articles/PMC7892885/ /pubmed/33603104 http://dx.doi.org/10.1038/s41598-021-83816-7 Text en © The Author(s) 2021 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
spellingShingle Article
Zhao, Xiangen
Becerra, Marley
Yang, Yongchao
He, Junjia
Elongation and branching of stem channels produced by positive streamers in long air gaps
title Elongation and branching of stem channels produced by positive streamers in long air gaps
title_full Elongation and branching of stem channels produced by positive streamers in long air gaps
title_fullStr Elongation and branching of stem channels produced by positive streamers in long air gaps
title_full_unstemmed Elongation and branching of stem channels produced by positive streamers in long air gaps
title_short Elongation and branching of stem channels produced by positive streamers in long air gaps
title_sort elongation and branching of stem channels produced by positive streamers in long air gaps
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7892885/
https://www.ncbi.nlm.nih.gov/pubmed/33603104
http://dx.doi.org/10.1038/s41598-021-83816-7
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