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Langmuir turbulence in the auroral ionosphere 1: Linear theoryIntense bursts of Langmuir waves with electric fields of 50 to 500 mV / m have been frequently observed at altitudes greater than 500 km in the auroral ionosphere. These bursts are driven by 20 eV to 4 keV field-aligned electrons, which are embedded in an approximately isotropic nonthermal tail of scattered electrons. The Langmuir bursts are often observed at altitudes where the ionosphere is moderately magnetized (OMEGA (sub e) approximately equals omega (sub pe)). Both the moderate magnetization and the scattered electrons have a major influence on the linear dispersion and damping of Langmuir waves. In particular, the linear dispersion is topologically different depending on whether the magnetic field is subcritical (OMEGA (sub e) less than omega (sub pe)) or supercritical (OMEGA (sub e) greater than omega (sub pe)). The correct dispersion and damping can account for the observed polarization of the Langmuir waves, which is very nearly parallel to the geomagnetic field. Inferred properties of the linear instability driven by the field-aligned electrons are discussed. The linear dispersion and damping derived here provide the basis for a nonlinear turbulence study described in a companion paper (Newman et al., this issue).
Document ID
19950029585
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Newman, D. L.
(Univ. of Colorado, Boulder, CO United States)
Goldman, M. V.
(Univ. of Colorado, Boulder, CO United States)
Ergun, R. E.
(Univ. of California, Berkeley, CA United States)
Boehm, M. H.
(Max-Planck-Institut Garching, Munich, Germany)
Date Acquired
August 16, 2013
Publication Date
April 1, 1994
Publication Information
Publication: Journal of Geophysical Research
Volume: 99
Issue: A4
ISSN: 0148-0227
Subject Category
Geophysics
Accession Number
95A61184
Funding Number(s)
CONTRACT_GRANT: NSF ATM-91-13375
CONTRACT_GRANT: NSF ATM-88-13255
CONTRACT_GRANT: NAG6-10
Distribution Limits
Public
Copyright
Other

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