Premium
Heating of ionospheric ion beams in inverted‐V structures
Author(s) -
Cui Y. B.,
Fu S. Y.,
Parks G. K.
Publication year - 2014
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 - 10.1002/2014gl060524
Subject(s) - ion , ionosphere , atomic physics , physics , flux (metallurgy) , ion beam , plasma sheet , range (aeronautics) , plasma , beam (structure) , materials science , geophysics , optics , magnetosphere , nuclear physics , quantum mechanics , metallurgy , composite material
Beams of H + , He + , and O + ions have been observed when the four Cluster satellites crossed the high‐latitude plasma sheet boundary layer at ∼4 R E . These beams appear as inverted‐V structures in the energy flux time spectrograms. The pitch angles of the beams range from ∼0 to 30° indicating the ions are streaming along the magnetic field out of the ionosphere. The streaming velocity is a few tens of km/s to several hundred km/s, consistent with the beams having gone through a potential drop of several tens of eV to a few keV. These beams are intense with beam to ambient density ratios, δ n b / n T , as large as ∼0.3. The beams are hotter than the ionospheric ion thermal energy, indicating the ions have been heated while accelerated along the magnetic field. We present first results that show the ions tend to be hotter at the peak (several hundred eV) than at the start of the inverted‐V structures (a few tens of eV). These results interpreted in terms of a U‐shaped potential structure indicate the hottest ions come from the central region where the potential difference is maximum.