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Observation of magnetospheric relativistic electrons accelerated by Pc‐5 ULF waves
Author(s) -
Tan Lun C.,
Fung Shing F.,
Shao Xi
Publication year - 2004
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 - 10.1029/2004gl019459
Subject(s) - physics , electron , electric field , pitch angle , van allen probes , magnetosphere , magnetic field , computational physics , acceleration , field line , van allen radiation belt , atomic physics , particle acceleration , geophysics , nuclear physics , classical mechanics , quantum mechanics
Magnetic field, electric field and energetic electron measurements from CRRES, GOES‐6 and ‐7 satellites are used to investigate the production of up to 2 MeV electron fluxes through a storm sudden commencement (SSC) event on August 27, 1991. Strong Pc‐5 oscillations, whose electric field is mainly along the radial direction, and up to an order‐of‐magnitude enhancement in relativistic electron fluxes occurred simultaneously in a two‐hour period. The enhanced electron fluxes are found to have a pancake‐like pitch angle distribution, which is consistent with the fluxes being accelerated near the equatorial plane. The electron acceleration is shown to result from drift‐resonant interactions with the toroidal‐mode Pc‐5 ULF waves having wave frequencies three times the electron drift frequency. In view of the L‐variation of ULF wave frequencies, electron acceleration to relativistic energies becomes more effective in the geosynchronous region.