000004749 001__ 4749
000004749 005__ 20200203142330.0
000004749 0247_ $$2DOI$$a10.3847/2041-8213/ab398b
000004749 037__ $$aSCART-2020-0051
000004749 100__ $$aLopez, R. A.
000004749 245__ $$aParticle-in-cell simulations of the whistler heat-flux instability in the solar wind conditions
000004749 260__ $$c2019
000004749 520__ $$aIn collision-poor plasmas from space, e.g., solar wind or stellar outflows, the heat flux carried by the strahl or beaming electrons is expected to be regulated by the self-generated instabilities. Recently, simultaneous field and particle observations have indeed revealed enhanced whistler-like fluctuations in the presence of counter-beaming populations of electrons, connecting these fluctuations to the whistler heat-flux instability (WHFI). This instability is predicted only for limited conditions of electron beam-plasmas, and has not yet been captured in numerical simulations. In this Letter we report the first simulations of WHFI in particle-in-cell setups, realistic for the solar wind conditions, and without temperature gradients or anisotropies to trigger the instability in the initiation phase. The velocity distributions have a complex reaction to the enhanced whistler fluctuations conditioning the instability saturation by a decrease of the relative drifts combined with induced (effective) temperature anisotropies (heating the core electrons and pitch-angle and energy scattering the strahl). These results are in good agreement with a recent quasilinear approach, and support therefore a largely accepted belief that WHFI saturates at moderate amplitudes. In the anti-sunward direction the strahl becomes skewed with a pitch-angle distribution decreasing in width as electron energy increases, which seems to be characteristic of self-generated whistlers and not to small-scale turbulence.
000004749 594__ $$aNO
000004749 6531_ $$amethods: numerical; plasmas; solar wind; waves; instabilities; interplanetary medium; Physics - Plasma Physics; Astrophysics - Solar and Stellar Astrophysics; Physics - Space Physics 
000004749 700__ $$aShaaban, S. M.
000004749 700__ $$aLazar, M.
000004749 700__ $$aPoedts, S.
000004749 700__ $$aYoon, P. H.
000004749 700__ $$aMicera, A.
000004749 700__ $$aLapenta, G.
000004749 773__ $$cL8$$n1$$pApJL$$v882
000004749 8560_ $$falfredo.micera@observatoire.be
000004749 905__ $$apublished in
000004749 980__ $$aREFERD