Kinetic theory of the Thermal Farley-Buneman Instability in the E-region ionosphere

TL;DR

This paper presents a comprehensive kinetic linear theory of the thermal Farley-Buneman instability in the E-region ionosphere, incorporating ion electric field effects and providing a detailed dispersion relation.

Contribution

It introduces the first kinetic description of the instability that includes the electric field, unifying various plasma instabilities in the E-region.

Findings

Derived a linear wave dispersion relation involving elementary functions and plasma dispersion functions.

The theory applies to plasma wave frequencies at or above the ion-neutral collision frequency.

Provides insights relevant for interpreting radar signals from high E-region altitudes.

Abstract

This paper develops a fully kinetic linear theory of the thermal Farley-Buneman instability (TFBI) in the E-region ionosphere with unmagnetized ions. The TFBI combines spatially uniform E-region plasma instabilities, such as the Farley-Buneman instability (FBI), ion thermal instability (ITI), and electron thermal instability (ETI). Similar collision-dominated plasma processes can also occur in the solar and stellar chromospheres, as well as in other planetary atmospheres. For the first time in the theory of the FBI-related processes, the kinetic description of ions includes the driving electric field, resulting in automatic inclusion of the ITI. This analytic theory has produced a comprehensive linear wave dispersion relation. It is remarkable that, similarly to the oversimplified earlier ion-kinetic studies, this much more general kinetic dispersion relation involves only elementary functions and the standard plasma dispersion function (albeit of several different arguments). This new theory is limited to plasma waves with the frequencies of the order, or larger than, the ion-neutral collision frequency. This inherently kinetic frequency range is of importance for accurate interpretation of radar signals scattered from relatively high E-region altitudes, but at altitudes where ions are unmagnetized (mostly, below 110 km).