Accession Number : ADA188875

Title :   Nonlinear Evolution of the Kelvin-Helmholtz Instability in the High Latitude Ionosphere.

Descriptive Note : Interim rept.,

Corporate Author : NAVAL RESEARCH LAB WASHINGTON DC

Personal Author(s) : Keskinen, M J ; Mitchell, H G ; Fedder, J A ; Satyanarayana, P ; Zalesak, S T

PDF Url : ADA188875

Report Date : 21 Dec 1987

Pagination or Media Count : 69

Abstract : The nonlinear evolution of the electrostatic Kelvin Helmholtz instability, resulting from velocity-sheared plasma flows perpendicular to an ambient magnetic field, has been studied including Pedersen conductivity effects (i.e., ion-neutral collisions). The Kelvin Helmholtz instability develops in a distinctly different manner in the nonlinear regime with Pedersen coupling than without it. Specifically, the Pedersen coupling effects, in conjunction with a neutral wind and density gradient, (1) result in an increased time scale for Kelvin Helmholtz instability wave growth. (2) inhibit Kelvin Helmholtz vortex formation, (3) lead to nonlinear structures which can be described as breaking waves, and (4) generate, in the nonlinear regime, small scale turbulence by means of secondary instabilities growing on the primary waves. The spatial power spectra of the electrostatic potential and density fluctuations, and it is found that there is a tendency for the potential and density to become shallower when Pedersen conductivity effects are included. The results are compared with recent Dynamics Explorer satellite observations of velocity sheared plasma flows in the high latitude, near-earth space plasma and good agreement is found.

Descriptors :   *PLASMAS(PHYSICS), *IONOSPHERIC DISTURBANCES, ARTIFICIAL SATELLITES, COLLISIONS, CONDUCTIVITY, COUPLING(INTERACTION), ELECTROSTATICS, EVOLUTION(GENERAL), FLOW, GRADIENTS, HIGH LATITUDES, IONOSPHERE, IONS, MAGNETIC FIELDS, NEUTRAL, NONLINEAR SYSTEMS, POWER SPECTRA, SCALE, SPACE SCIENCES, SPATIAL DISTRIBUTION, TIME, TURBULENCE, WIND, VORTICES, ION DENSITY, ELECTRICAL CONDUCTIVITY

Subject Categories : Atmospheric Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE