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Analysis of EMIC‐wave‐moderated flux limitation of measured energetic ion spectra in multispecies magnetospheric plasmas
Author(s) -
Mauk B. H.
Publication year - 2013
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/grl.50789
Subject(s) - physics , ion , magnetosphere , spectral line , atomic physics , computational physics , flux (metallurgy) , cyclotron , plasma , ionosphere , geophysics , nuclear physics , astronomy , materials science , quantum mechanics , metallurgy
A differential Kennel‐Petschek (KP) flux limit for magnetospheric energetic ions is devised taking into account multiple ion species effects on electromagnetic ion cyclotron (EMIC) waves that scatter the ions. The idea is that EMIC waves may limit the highest ion intensities during acceleration phases of storms and substorms (~ hour) while other mechanisms (e.g., charge exchange) may account for losses below those limits and over longer periods of time. This approach is applied to published Earth magnetosphere energetic ion spectra (~ keV to ~1 MeV) for radial positions ( L ) 3 to 6.7 R E . The flatness of the most intense spectral shapes for <100 keV indicate sculpting by just such a mechanism, but modifications of traditional KP parameters are needed to account for maximum fluxes up to 5.4 times greater than expected. Future work using the new capabilities of the Van Allen Probes mission will likely resolve outstanding uncertainties.