Particle-in-cell Simulations of the Whistler Heat-flux Instability in Solar Wind Conditions

López, R. A. and Shaaban, S. M. and Lazar, M. and Poedts, S. and Yoon, P. H. and Micera, A. and Lapenta, G. (2019) Particle-in-cell Simulations of the Whistler Heat-flux Instability in Solar Wind Conditions. The Astrophysical Journal, 882 (1). L8. ISSN 2041-8213

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Abstract

In collision-poor plasmas from space, e.g., solar wind or stellar outflows, the heat flux carried by the strahl or beaming electrons is expected to be regulated by the self-generated instabilities. Recently, simultaneous field and particle observations have indeed revealed enhanced whistler-like fluctuations in the presence of counter-beaming populations of electrons, connecting these fluctuations to the whistler heat-flux instability (WHFI). This instability is predicted only for limited conditions of electron beam-plasmas, and has not yet been captured in numerical simulations. In this Letter we report the first simulations of WHFI in particle-in-cell setups, realistic for the solar wind conditions, and without temperature gradients or anisotropies to trigger the instability in the initiation phase. The velocity distributions have a complex reaction to the enhanced whistler fluctuations conditioning the instability saturation by a decrease of the relative drifts combined with induced (effective) temperature anisotropies (heating the core electrons and pitch-angle and energy scattering the strahl). These results are in good agreement with a recent quasilinear approach, and support therefore a largely accepted belief that WHFI saturates at moderate amplitudes. In the anti-sunward direction the strahl becomes skewed with a pitch-angle distribution decreasing in width as electron energy increases, which seems to be characteristic of self-generated whistlers and not to small-scale turbulence.

Item Type: Article
Subjects: Science Global Plos > Physics and Astronomy
Depositing User: Unnamed user with email support@science.globalplos.com
Date Deposited: 01 Jun 2023 10:06
Last Modified: 16 Jan 2024 05:07
URI: http://ebooks.manu2sent.com/id/eprint/988

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