Langmuir Turbulence in the Auroral Ionosphere: Origins and Effects

Frontiers in Astronomy and Space Sciences

David L. Newman¹  Hassanali Akbari²  James W. LaBelle³ 

[1] Boulder, CO, United States;Greenbelt, MD, United States;Hanover, NH, United States;

关键词: Langmuir turbulence;    auroral ionosphere;    beam-plasma interactions;    plasma waves;    radar echoes;   

DOI  :  10.3389/fspas.2020.617792

来源: Frontiers

【 摘 要 】

Theory and observations of Langmuir waves and turbulence induced in the auroral ionosphere by electron beams of magnetospheric-origin are reviewed. The theoretical discussions include a brief description of the electrostatic dispersion relation, excitation of Langmuir waves by electron beams, and the stability of beam distributions. The theory of Langmuir turbulence—including the parametric decay instability and wave collapse—is also briefly discussed. The main focus of the review, however, is on the observations of Langmuir waves and turbulence in the ionosphere by in-situ and ground-based sensors. A summary of five decades of in-situ wave and particle observations is presented and combined with a collection of more recent results from ground-based instruments. The ground-based observations include signatures of Langmuir turbulence in the form of coherent echoes in incoherent scatter radar measurements; signatures of electron beams in the form of auroral morphologies recorded by high-speed, high-resolution optical imagers; and electromagnetic emissions received on the ground at high latitudes. Uniting the various observations obtained by the vastly different sensors is shown to provide further insight into the micro-scale processes that occur in the ionosphere. Also discussed in this review is the potential of the ground-based sensors to provide a broader spatial and temporal context for single-point in-situ measurements of such processes.

【 授权许可】

CC BY