 |
| Titel |
Beads and glows in sprite discharges resulting from a dynamical instability of streamer channels. |
| VerfasserIn |
Alejandro Luque Estepa, Hans C. Stenbaek-Nielsen, Matthew G. McHarg, Ryan K. Haaland |
| Konferenz |
EGU General Assembly 2015
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250110794
|
| Publikation (Nr.) |
 EGU/EGU2015-10831.pdf |
|
|
|
|
|
| Zusammenfassung |
| High-speed video recordings of sprite discharges show patches of luminosity appearing some
milliseconds after a streamer channel is formed [1]. Called beads or glows depending on their
size, these luminous patches have decay times of tens of milliseconds and they are
responsible for most of the light emitted by the sprite [2].
A possible mechanism explaining the frequent formation of beads and glows is called
"attachment instability". This is a dynamical instability inherent in streamer channels that
results when a locally higher electric field enhances the effective attachment rate and reduces
the electron density. In turn, a depleted electron density enhances the electric field, thus
feeding the instability. The instability can be triggered by small perturbations to the streamer
channel, such as those arising from a pre-existing inhomogeneity in the electron density
[3].
We present observations of the formation of beads and glows and measurements of their
decay times. Then we compare with numerical simulations of a streamer channel where the
attachment instability generates bright patches with a high electric field. Most of
the observed properties of beads and glows are present in the simulation, which
leads us to believe that these features are indeed manifestations of the attachment
instability.
[1] H. C. Stenbaek-Nielsen and M. G. McHarg, J. Phys. D 41, 234009 (2008).
[2] H. C. Stenbaek-Nielsen , T. Kanmae, M. G. McHarg and R. K. Haaland, Surv.
Geophys. 34:769-795 (2013).
[3] A. Luque and F. J. Gordillo-Vázquez, Geophys. Res. Lett. 38, L04808 (2011). |
|
|
|
|
|
|