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Monoenergetic high‐energy electron precipitation in thin auroral filaments
Author(s) -
Dahlgren H.,
Ivchenko N.,
Lanchester B. S.
Publication year - 2012
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2012gl053466
Subject(s) - electron precipitation , precipitation , dispersion (optics) , electron , ion , atmospheric sciences , physics , atomic physics , environmental science , plasma , meteorology , nuclear physics , optics , magnetosphere , quantum mechanics
The energy distribution of the electron precipitation responsible for extremely narrow (70 m) and dynamic auroral filaments is found to be sharply peaked at around 8 keV. The events were captured with high resolution low‐light optical imagers located near Tromsø, Norway. The method uses imaging in two emissions which have different energy dependent responses to auroral electron precipitation. The key feature of the events was that no difference in the altitude of the two emissions was detected, nor any time‐of‐flight dispersion, thus leading to the conclusion that the filaments were caused by monoenergetic precipitation. Comparisons with an electron transport and ion chemistry model show that the high energy filaments were embedded in a region of lower energy precipitation of about 4 keV. There is currently no consistent theory to explain the characteristics of the observed auroral structures.