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Initial FAST observations of acceleration processes in the cusp
Author(s) -
Pfaff R.,
Clemmons J.,
Carlson C.,
Ergun R.,
McFadden J.,
Mozer F.,
Temerin M.,
Klumpar D.,
Peterson W.,
Shelley E.,
Mœbius E.,
Kistler L.,
Strangeway R.,
Elphic R.,
Cattell C.
Publication year - 1998
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 - 10.1029/98gl00936
Subject(s) - magnetosheath , physics , particle acceleration , electron , ion , cusp (singularity) , acceleration , computational physics , particle (ecology) , electric field , charged particle , geophysics , pitch angle , plasma , astrophysics , atomic physics , magnetosphere , geology , classical mechanics , geometry , magnetopause , nuclear physics , mathematics , oceanography , quantum mechanics
FAST satellite observations during two encounters with the Earth's cusps near 4000 km are presented. In addition to precipitating magnetosheath particles with isotropic pitch angle distributions, the energetic particle data reveal upgoing ion beams, ion conics, downgoing “inverted‐V” electron distributions, and very narrow, intense upgoing electron beams. A rich assortment of DC‐coupled electric fields and plasma waves accompany these acceleration processes. In one example, step‐like injections of magnetosheath ions are correlated with bursts of upgoing ion beams and downgoing electrons, suggesting that the currents associated with these injections set up local electric potential structures that subsequently drive the acceleration processes. The observations underscore the fact that the cusp is not merely a conduit for the passage of magnetosheath particles and fields, but contains a dynamic internal electrical structure that accelerates particles locally and may alter the precipitating magnetosheath particle populations themselves.