Quasilinear Evolution of Kinetic Alfven Wave Turbulence and Perpendicular Ion Heating in the Solar Wind

TL;DR

This paper models how kinetic Alfven wave turbulence in the solar wind leads to ion heating, showing that wave-particle interactions cause increased perpendicular ion temperatures through quasi-linear diffusion and subsequent instabilities.

Contribution

It introduces a model linking kinetic Alfven wave turbulence to ion heating via quasi-linear diffusion and instability analysis in the solar wind.

Findings

Ion distribution becomes unstable to electromagnetic ion cyclotron waves.

Ion pitch-angle scattering increases perpendicular ion temperature.

Wave turbulence contributes to ion heating in the solar wind.

Abstract

The measured spectrum of kinetic Alfven wave fluctuations in the turbulent solar wind plasma is used to calculate the electron and ion distribution functions resulting from quasi-linear diffusion. The modified ion distribution function is found to be unstable to long wavelength electromagnetic ion cyclotron waves. These waves pitch angle scatter the parallel ion velocity into perpendicular velocity which effectively increases the perpendicular ion temperature.