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Models for electrostatic drift waves with density variations along magnetic field lines
Author(s) -
Garcia O. E.,
Pécseli H. L.
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 - 10.1002/2013gl057802
Subject(s) - physics , magnetic field , electron precipitation , geophysics , plasma , computational physics , amplitude , gravitational wave , flux tube , electric field , field line , ionosphere , magnetic flux , mechanics , magnetosphere , astrophysics , optics , quantum mechanics
Drift waves with vertical magnetic fields in gravitational ionospheres are considered where the unperturbed plasma density is enhanced in a magnetic flux tube. The gravitational field gives rise to an overall decrease of plasma density for increasing altitude. Simple models predict that drift waves with finite vertical wave vector components can increase in amplitude merely due to a conservation of energy density flux of the waves. Field‐aligned currents are some of the mechanisms that can give rise to fluctuations that are truly unstable. We suggest a self‐consistent generator or “battery” mechanism that in the polar ionospheres can give rise to magnetic field‐aligned currents even in the absence of electron precipitation. The free energy here is supplied by steady state electric fields imposed in the direction perpendicular to the magnetic field in the collisional lower parts of the ionosphere or by neutral winds that have similar effects.