Early time evolution of a chemically produced electron depletion

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TR Number

Date

1995-01-01

Journal Title

Journal ISSN

Volume Title

Publisher

American Geophysical Union

Abstract

The early time evolution of an ionospheric electron depletion produced by a radially expanding electron attachment chemical release is studied with a two-dimensional simulation model. The model includes electron attachment chemistry, incorporates fluid electrons, particle ions and neutrals, and considers the evolution in a plane perpendicular to the geomagnetic field for a low beta plasma. Timescales considered are of the order of or less than the cyclotron period of the negative ions that result as a by-product of the electron attachment reaction. This corresponds to time periods of tenths of seconds during recent experiments. Simulation results show that a highly sheared azimuthal electron flow velocity develops in the radially expanding depletion boundary. This sheared electron flow velocity and the steep density gradients in the boundary give rise to small-scale irregularities in the form of electron density cavities and spikes. The nonlinear evolution of these irregularities results in trapping and ultimately turbulent heating of the negative ions.

Description

Keywords

F-region, Plasma, Instability, Clouds, Driven, Shear

Citation

Scales, W. A., P. A. Bernhardt, and G. Ganguli (1995), Early time evolution of a chemically produced electron depletion, J. Geophys. Res., 100(A1), 269-280, doi:10.1029/94JA02490.