 |
| Titel |
On the Electric Breakdown Field of the Mesosphere and the Influence of Electron Detachment |
| VerfasserIn |
Torsten Neubert, Olivier Chanrion |
| Konferenz |
EGU General Assembly 2013
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250080443
|
|
|
|
|
|
| Zusammenfassung |
| The breakdown field of the atmosphere, Ek, is commonly understood as the field value at
which the ionization rate equals the attachment rate of electrons to neutrals. This description
has worked well for the lower atmosphere and has been applied to the discharges of the
mesosphere, the sprites and giant jets, with much success. However, in the dilute mesosphere,
where neutral densities are 4-5 orders of magnitude lower than at sea level, the process of
electron associative detachment from negative atomic oxygen ions is also important and
provides an additional source of free electrons. We show that the introduction of the
detachment process allows for electron avalanche growth for any electric field magnitude,
provided the exposure time is long enough. The concept of a threshold field therefore itself
breaks down. For realistic source electric fields, the threshold may be as low as 0.7 Ek, which
relaxes the requirement on the field magnitude for initiation of sprites. We find
that the detachment process does not affect the time delays of sprites, as has been
proposed by others, and that detachment may decrease the conductivity of streamers. |
|
|
|
|
|
|