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Ion radial diffusion in an electrostatic impulse model for stormtime ring current formation
Author(s) -
Chen Margaret W.,
Schulz Michael,
Lyons Larry R.,
Gorney David J.
Publication year - 1992
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 - 10.1029/92gl00392
Subject(s) - ring current , physics , substorm , adiabatic process , van allen probes , electric field , diffusion , ion , computational physics , convection , guiding center , atomic physics , impulse (physics) , van allen radiation belt , magnetic field , magnetosphere , mechanics , classical mechanics , quantum mechanics
Guiding‐center simulations of stormtime transport of ring‐current and radiation‐belt ions having first adiabatic invariants μ ≳ 15 MeV/G (E ≳ 165 keV at L ∼ 3) are surprisingly well described (typically within a factor of ≲ 4) by the quasilinear theory of radial diffusion. This holds even for the case of an individual model storm characterized by substorm‐associated impulses in the convection electric field, provided that the actual spectrum of the electric field is incorporated in the quasilinear theory. Correction of the quasilinear diffusion coefficient D L L q lfor drift‐resonance broadening (so as to define D L L r b ) reduced the typical discrepancy with the diffusion coefficients D L L s i mdeduced from guiding‐center simulations of representative‐particle trajectories to a factor ∼3. The typical discrepancy was reduced to a factor ∼ 1.4 by averaging D L L s i m , D L L q l , and D L L r bover an ensemble of model storms characterized by different (but statistically equivalent) sets of substorm‐onset times.