Alternative explanation of the Doppler spectra of current-driven plasma instabilities
Radar observations of Doppler spectra from electron density irregularities in the auroral and equatorial electrojets often fall into two categories: narrow spectra with constant Doppler shifts and broad spectra with Doppler shifts dependent on the angle between the radar wave vector and the mean electron drift direction. Until now these spectra have been related to the two-stream and gradient-drift instabilities, respectively. In this paper we examine whether effects other than direct association of the instability type with the spectral type could reproduce the spectral observations. In particular, we make three assumptions: (1) both two-stream and gradient-drift irregularities have angle-dependent Doppler shifts, (2) the electron drift direction within the scattering volume is broadened due to plasma turbulence or spatial structure, and (3) the scattering cross section (mean square density fluctuation) is dependent on the angle between the radar wave vector and the local electron drift direction. These assumptions are sufficient to reproduce many of the spectral observations, including Doppler velocity plateaus. The plateau velocities under these assumptions have magnitudes that are slightly less than the electron drift velocity.
- Research Organization:
- Max-Planck-Institut fuer Aeronomie, Lindau 3, West Germany
- OSTI ID:
- 6270631
- Journal Information:
- J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 84:A2; ISSN JGREA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
Ionospheric
& Magetospheric Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CURRENTS
DATA
DATA FORMS
DOPPLER EFFECT
ELECTRIC CURRENTS
ELECTROJETS
EXPERIMENTAL DATA
INFORMATION
INSTABILITY
ISOLATED VALUES
NUMERICAL DATA
PLASMA INSTABILITY
TURBULENCE
VELOCITY