Electrostatic Instabilities in Highly Collisional Magnetized Plasmas with Multi-Species Ions

Collisional plasma instabilities in low-ionized, highly dissipative, weakly magnetized plasmas play an important role in the lower Earth's ionosphere and, potentially, in other planetary ionospheres. In the Solar chromosphere, macroscopic effects of collisional plasma instabilities may contribute into significant chromospheric heating --- an effect originally deduced from spectroscopic observations and relevant modeling. We have developed a unified linear theory of local plasma instabilities, such as the Farley-Buneman, electron thermal, and ion thermal instabilities, in collisional plasmas with fully or partially unmagnetized multi-species ions. Theoretical analysis, based on a simplified 5-moment multi-fluid model, produces the general linear dispersion relation for the combined instability. Important limiting cases are analyzed in detail. This analysis demonstrates the acceptable applicability of this multi-fluid model for the processes under study. Fluid model simulations usually require much less computer resources than do more accurate kinetic simulations, so that the apparent success of the fluid-model approach to the linear theory of collisional plasma instabilities makes it possible to include these small-scale instabilities (along with their possible macroscopic effects) into global fluid codes originally developed for large-scale modeling of the Solar and planetary atmospheres.