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Observations of an upward‐directed electron beam with the perpendicular temperature of the cold ionosphere
Author(s) -
Boehm M. H.,
Clemmons J.,
Wahlund J.E.,
Eriksson A.,
Eliasson L.,
Blomberg L.,
Kintner P.,
Höfner H.
Publication year - 1995
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 - 10.1029/95gl01777
Subject(s) - ionosphere , physics , electron , atomic physics , ion , electric field , particle acceleration , electron precipitation , beam (structure) , perpendicular , electron temperature , computational physics , geophysics , optics , plasma , magnetosphere , nuclear physics , geometry , mathematics , quantum mechanics
The Freja TESP electron spectrometer has repeatedly observed ∼100 eV ‐ 1 keV upward‐directed, anti‐field‐aligned electron beams near 1700 km altitude in the auroral zone. A particularly intense event, at energies up to 2 keV, is described. The beam perpendicular temperature T ⟂ e was as low as 0.1–0.2 eV at 100–200 eV parallel energy. The 10–15 s period of upward fluxes was coincident with a low density (∼10 cm −3 ) period and a ∼5 keV ion conic. Strong low frequency waves and the lack of any downward motion in the simultaneously observed ion conic suggest a strong element of wave acceleration, while electric field and ion loss cone measurements provide limited evidence of potential acceleration to a fraction of the observed energies.