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Plasma density enhancements in the high‐altitude polar cap region observed on Akebono
Author(s) -
Ichikawa Yohichi,
Abe Takumi,
Yau Andrew W.
Publication year - 2002
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 - 10.1029/2001gl013723
Subject(s) - ionosphere , plasma , polar , electron temperature , physics , convection , atmospheric sciences , electron density , geophysics , ion , altitude (triangle) , f region , drift velocity , atomic physics , meteorology , astronomy , nuclear physics , geometry , mathematics , quantum mechanics
The plasma density in the polar cap ionosphere is generally low (<10 3 cm −3 above 3000 km), mainly because of plasma escape from the ionosphere along open magnetic‐field lines. The Akebono satellite occasionally encounters regions of unusually high plasma density (≥10 3 cm −3 ) above 4000 km altitude, in which the thermal plasma exhibits a distinctively low electron temperature (<3000 K) and low parallel ion drift velocity (≤1 km/s). Such events are almost always observed on the dusk side. The occurrence of low electron temperature and ion drift velocity appears to suggest the antisunward convection of high‐density plasma into the polar cap, and the decrease in electron temperature due to the disruption of field‐aligned heat flux in the high‐altitude polar cap.