Virginia TechScales, Wayne A.Bernhardt, P. A.Ganguli, Gurudas2014-02-052014-02-051995-01-01Scales, 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:10.1029/94JA02490.0148-0227http://hdl.handle.net/10919/25320The 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.application/pdfenIn CopyrightF-regionPlasmaInstabilityCloudsDrivenShearArticle - Refereedhttp://onlinelibrary.wiley.com/doi/10.1029/94JA02490/pdfhttps://doi.org/10.1029/94ja02490