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Peculiar pitch angle distribution of relativistic electrons in the inner radiation belt and slot region
Author(s) -
Zhao H.,
Li X.,
Blake J. B.,
Fennell J. F.,
Claudepierre S. G.,
Baker D. N.,
Jaynes A. N.,
Malaspina D. M.,
Kanekal S. G.
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 - 10.1002/2014gl059725
Subject(s) - van allen radiation belt , physics , electron , pitch angle , radiation , geophysics , distribution (mathematics) , geology , computational physics , geodesy , nuclear physics , magnetosphere , plasma , mathematical analysis , mathematics
The relativistic electrons in the inner radiation belt have received little attention in the past due to sparse measurements and unforgiving contamination from the inner belt protons. The high‐quality measurements of the Magnetic Electron Ion Spectrometer instrument onboard Van Allen Probes provide a great opportunity to investigate the dynamics of relativistic electrons in the low L region. In this letter, we report the newly unveiled pitch angle distribution (PAD) of the energetic electrons with minima at 90° near the magnetic equator in the inner belt and slot region. Such a PAD is persistently present throughout the inner belt and appears in the slot region during storms. One hypothesis for 90° minimum PADs is that off 90° electrons are preferentially heated by chorus waves just outside the plasmapause (which can be at very low L during storms) and/or fast magnetosonic waves which exist both inside and outside the plasmasphere.