Linear theory of weakly amplified, parallel propagating, transverse temperature anisotropy instabilities in magnetized thermal plasmas

TL;DR

This paper provides an analytical framework for understanding weakly amplified transverse instabilities in magnetized plasmas, explaining observed solar wind turbulence and confinement limits at low plasma beta.

Contribution

It offers a rigorous analytical dispersion relation analysis for transverse instabilities in anisotropic magnetized plasmas, linking theory with solar wind observations.

Findings

Identifies conditions for Alfven-proton-cyclotron and Alfven-Whistler-electron-cyclotron instabilities.

Explains observed solar wind magnetic turbulence characteristics.

Accounts for confinement limits at small parallel plasma beta.

Abstract

A rigorous analytical study of the dispersion relations of weakly amplified transverse fluctuations with wave vectors ($\vec{k}\parallel \vec{B}$) parallel to the uniform background magnetic field $\vec{B}$ in an anisotropic bi-Maxwellian magnetized electron-proton plasma is presented. We determine the conditions for which the weakly amplified LH-handed polarized Alfven-proton-cyclotron and RH-handed polarized Alfven-Whistler-electron-cyclotron branches can be excited. The results of our instability study are applied to the observed solar wind magnetic turbulence. The Alfvenic instability diagram explains well the main characteristic properties of the observed solar wind fluctuations. Especially, the observed confinement limits at small parallel plasma beta values are explained.