Collisions of neutral gas with dusty plasma support explanations of natural phenomena in Earth’s ionosphere
Collisions of neutral gas with dusty plasma support explanations of natural phenomena in Earth’s ionosphere lead image
High above Earth, there is a dusty band in the ionosphere stretching some 80 to 120 kilometers above the surface. It is filled with electrons, ion species, neutrals, and larger dust grains created by falling meteorites. This dusty plasma plays an important role in modulating wave processes occurring in the ionosphere and outer space and has received renewed interest in recent years.
Morozova et al. studied inelastic collisions of neutrals with charged particles in dusty ionospheric plasma for the first time. The authors specifically studied the effect of the collisions on the modulational instability of electromagnetic waves – a type of strong nonlinear interaction important for creating turbulence.
Developing mathematical models to describe the collisions’ effects on the modulational instability, the authors were able to study the how the instabilities grew. The results showed the influence due to collisions of electrons and ions with neutrals is usually less significant than collisions between dust grains and neutrals.
“Our results are important for the explanation and description of different natural phenomena,” said author Tatiana Morozova. “Furthermore, the processes described in our paper should be taken into account when describing the propagation of electromagnetic waves at altitudes of 90 to 120 kilometers.”
For example, the results help explain why there is often a lack of low-frequency ionospheric noise during noctilucent cloud events and polar mesosphere summer echoes, since at the heights of these phenomena, the dusty ionospheric plasma suppresses the growth of modulational instabilities. It also helps explain enhancements sometimes seen as green nightglow in the upper atmosphere.
Source: “Some aspects of modulational interaction in Earth’s dusty ionosphere,” by T. I. Morozova, S. I. Kopnin, S. I. Popel, and N. D. Borisov, Physics of Plasmas (2021). The article can be accessed at https://doi.org/10.1063/5.0040271 .
