Quasilinear Approach of the Whistler Heat-Flux Instability in the Solar Wind

The hot beaming (or strahl) electrons responsible for the main electron heat-flux in the solar wind are believed to be self-regulated by the electromagnetic beaming instabilities, also known as the heat-flux instabilities. Here we report the first quasi-linear theoretical approach of the whistler unstable branch able to characterize the long-term saturation of the instability as well as the relaxation of the electron velocity distributions. The instability saturation is not solely determined by the drift velocities, which undergo only a minor relaxation, but mainly from a concurrent interaction of electrons with whistlers that induces (opposite) temperature anisotropies of the core and beam populations and reduces the e ective anisotropy. These results might be able to (i) explain the low intensity of the whistler heat-flux fluctuations in the solar wind (although other explanations remain possible and need further investigation), and (ii) con rm a reduced effectiveness of these fluctuations in the relaxation and isotropization of the electron strahl and in the regulation of the electron heat-flux.

Publication year:2019

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BOF-publication weight:2

CSS-citation score:2

Authors:International

Authors from:Higher Education

Accessibility:Open