Nonlinear evolution of the Kelvin-Helmholtz instability in the high-latitude ionosphere. Interim report

Technical Report · Mon Dec 21 04:00:00 EST 1987

OSTI ID:5268725

Keskinen, M J; Mitchell, H G; Fedder, J A; Satyanarayana, P; Zalesak, S T

The nonlinear evolution of the electrostatic Kelvin-Helmholtz instability, resulting from velocity-sheared plasma flows perpendicular to an ambient magnetic field, was 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 that 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.

• Research Organization: Naval Research Lab., Washington, DC (USA)
• OSTI ID: 5268725
• Report Number(s): AD-A-188875/9/XAB; NRL-MR-6043
• Country of Publication: United States
• Language: English

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71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CHARGED PARTICLES
COLLISIONS
DISTRIBUTION
EARTH ATMOSPHERE
ELECTROSTATICS
HELMHOLTZ INSTABILITY
INSTABILITY
ION DENSITY
IONOSPHERE
IONS
MAGNETIC FIELDS
NONLINEAR PROBLEMS
PLANETARY IONOSPHERES
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
SPATIAL DISTRIBUTION
TURBULENCE
VORTICES
WIND