Cavitating Langmuir Turbulence in the Terrestrial Aurora

TL;DR

This paper provides the first direct evidence that cavitating Langmuir turbulence naturally occurs in the Earth's ionosphere, driven by auroral electron beams and characterized by cascading plasma wave excitations.

Contribution

It demonstrates the occurrence of natural cavitating Langmuir turbulence in the ionosphere through spectral measurements and modeling, a phenomenon previously only artificially produced.

Findings

Natural cavitating Langmuir turbulence occurs in the ionosphere.

Auroral electron beams drive Langmuir waves leading to turbulence.

First direct evidence of such turbulence in space plasma.

Abstract

Langmuir cavitons have been artificially produced in the earth's ionosphere, but evidence of naturally-occurring cavitation has been elusive. By measuring and modeling the spectra of electrostatic plasma modes, we show that natural cavitating, or strong, Langmuir turbulence does occur in the ionosphere, via a process in which a beam of auroral electrons drives Langmuir waves, which in turn produce cascading Langmuir and ion-acoustic excitations and cavitating Langmuir turbulence. The data presented here are the first direct evidence of cavitating Langmuir turbulence occurring naturally in any space or astrophysical plasma.