Role of Collisions with Neutrals in the Process of Modulational Excitation of Dust Acoustic Perturbations in Dusty Ionosphere

Abstract

The role of inelastic collisions of electrons and ions with neutrals during the development of modulational instability involving dust acoustic perturbations in dusty ionospheric plasma, as well as the effect of collisions of electrons, ions, and dust grains with neutrals on the manifestations of modulational interaction in the dusty ionosphere, are estimated. It is shown that, in this case, the influence of collisions of electrons and ions with neutrals is usually less significant than the influence of collisions between dust grains and neutrals. It is demonstrated that the effect of modulational instability on the propagation of electromagnetic waves in the dusty ionospheric plasma is the most significant at altitudes of 100–120 km. The modulational interaction in the dusty ionosphere is important for the explanation of such effects as ground-based observations of low-frequency ionospheric radio noises with frequencies below 50 Hz, generation of infrasonic waves in the ionosphere and the possibility to detect them near the Earth’s surface, enhancement of the green nightglow emission at a wavelength of 557.7 nm from the lower ionosphere layer at altitudes of 110–120 km, and modulational excitation of inhomogeneities in the electron and ion densities in the ionosphere at altitudes of 100–120 km. The absence of observations of low-frequency ionospheric radio noise during such phenomena as noctilucent clouds and polar mesosphere summer echoes caused by the presence of dusty plasma at altitudes of 80–95 km is explained. It is shown that the latter phenomenon is related to the suppression of modulational processes at these altitudes.