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 |
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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 |