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9MODULATIONAL INSTABILITY AND DUST FLOWS IN THE EARTH'S
IONOSPHERE
Yu.N. Izvekova, S.I. Popel
Space Research Institute, Russian Academy of Sciences, Moscow, Russia
Strongly anisotropic flow structures in planets' atmospheres and ionospheres are usually formed by neutral gas while the influence of electrons and ions is negligible for many situations. However in terrestrial ionosphere the conditions when zonal flows and streamers are formed as a result of plasma effects can be fulfilled. This can occur in dusty ionospheric plasma when we can consider flows of matter as strongly anisotropic dust flow structures. We study the case when collisions of stationary neutrals with electrons and ions are more frequent than those between electrons and ions. Furthermore, we assume that the phase speed and the wavelength of the perturbations are much smaller than the ion thermal speed and the collisional mean free pass (for electrons and ions), respectively. We show that the interaction [1] of dust particles with acoustic gravity vortices at ionospheric altitudes can result in the formation of initial vortical perturbation in a dust cloud. We describe the modulational instability leading to dust flow generation as a result of nonlinear interaction of dust vortices with dust flows which is characterized by the growth rate y. We determine the parameters of dust vortex. The formation of vertical and zonal dust flows is shown to be possible at the altitudes higher than 90 km. At lower altitudes the formation of dust flows is restricted because of very frequent collisions with neutrals. Generation of dust flows as a result of the modulational instability is demonstrated to result in sufficient redistribution of dust particles in the ionosphere.
This work was supported by the Russian Foundation for Basic Research (project nos. 14-05-31410 Mon_a)
1. Yu. N. Izvekova, S. I. Popel, and P. K. Shukla, AIP Conference Proceedings, 1397, 243 (2011).
