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Ion heating, electron acceleration, and the self‐consistent parallel E‐field in downward auroral current regions
Author(s) -
Jasperse John R.
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 - 10.1029/98gl02666
Subject(s) - physics , electron , particle acceleration , flux tube , ion , atomic physics , plasma , computational physics , current (fluid) , earth's magnetic field , substorm , magnetosphere , magnetic field , magnetic flux , nuclear physics , quantum mechanics , thermodynamics
Downward auroral current regions are characterized by: upflowing field‐aligned electrons; transverse ion heating; depleted plasma densities; downward‐pointing parallel E‐fields and current densities; intense ELF and VLF plasma wave activity; and the absence of hot magnetospheric particles. In this paper, we present a kinetic model that explains all of these features. We imagine a geomagnetic flux tube of finite length imbedded in a downward current region and impose appropriate kinetic boundary conditions. We assume that broadband ELF waves exist on the flux tube and heat the ions by cyclotron resonance near the ion gyrofrequency. We carry out an iterative, steady‐state solution for the one‐particle distribution functions, f α ( s , ν ⟂ , ν ∥ ), and the self‐consistent parallel E‐field, E ∥ ( s ). When this theory is applied to the Gorney et al. [1985] data set, we find good agreement between theory and experiment for the ion conic, the electron beam, and the downward‐pointing E ∥ ( s ).