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Electron-Driven Instabilities in the Solar Wind
Journal article   Open access   Peer reviewed

Electron-Driven Instabilities in the Solar Wind

Daniel Verscharen, B. D. G. Chandran, E. Boella, J. Halekas, M. E. Innocenti, V. K. Jagarlamudi, A. Micera, V. Pierrard, S. Stverak, I. Y. Vasko, …
Frontiers in astronomy and space sciences, Vol.9, 951628
08/03/2022
DOI: 10.3389/fspas.2022.951628
url
https://doi.org/10.3389/fspas.2022.951628View
Published (Version of record) Open Access

Abstract

The electrons are an essential particle species in the solar wind. They often exhibit non-equilibrium features in their velocity distribution function. These include temperature anisotropies, tails (kurtosis), and reflectional asymmetries (skewness), which contribute a significant heat flux to the solar wind. If these non-equilibrium features are sufficiently strong, they drive kinetic micro-instabilities. We develop a semi-graphical framework based on the equations of quasi-linear theory to describe electron-driven instabilities in the solar wind. We apply our framework to resonant instabilities driven by temperature anisotropies. These include the electron whistler anisotropy instability and the propagating electron firehose instability. We then describe resonant instabilities driven by reflectional asymmetries in the electron distribution function. These include the electron/ion-acoustic, kinetic Alfven heat-flux, Langmuir, electron-beam, electron/ion-cyclotron, electron/electron-acoustic, whistler heat-flux, oblique fast-magnetosonic/whistler, lower-hybrid fan, and electron-deficit whistler instability. We briefly comment on non-resonant instabilities driven by electron temperature anisotropies such as the mirror-mode and the non-propagating firehose instability. We conclude our review with a list of open research topics in the field of electron-driven instabilities in the solar wind.
Physical Sciences Astronomy & Astrophysics Science & Technology

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