Particle-In-Cell Simulations of Sunward and Anti-sunward Whistler Waves in the Solar Wind

Abstract

Spacecraft observations showed that electron heat conduction in the solar wind is probably regulated by whistler waves, whose origin and efficiency in electron heat flux suppression is actively investigated. In this paper, we present Particle-In-Cell simulations of a combined whistler heat flux and temperature anisotropy instability that can operate in the solar wind. The simulations are performed in a uniform plasma and initialized with core and halo electron populations typical of the solar wind. We demonstrate that the instability produces whistler waves propagating both along (anti-sunward) and opposite (sunward) to the electron heat flux. The saturated amplitudes of both sunward and anti-sunward whistler waves are strongly correlated with their {\it initial} linear growth rates, $B_w/B_0\sim (\gamma /{\omega }_{ce}{)}^{\nu }$, where for typical electron betas we have $0.6\lesssim \nu \lesssim 0.9$. The correlations of whistler wave amplitudes and spectral widths with plasma parameters (electron beta and temperature anisotropy) revealed in the simulations are consistent with those observed in the solar wind. The efficiency of electron heat flux suppression is positively correlated with the saturated amplitude of sunward whistler waves. The electron heat flux can be suppressed by 10--60% provided that the saturated amplitude of sunward whistler waves exceeds about 1% of background magnetic field. Other experimental applications of the presented results are discussed.

References in corpus (19)

• Particle acceleration in relativistic collisionless shocks: Fermi process at last?
• Electrons in the Young Solar Wind: First Results from the Parker Solar Probe
• Whistler mode waves and the electron heat flux in the solar wind: Cluster observations
• Statistical Study of Whistler Waves in the Solar Wind at 1 AU
• Experimental determination of whistler wave dispersion relation in the solar wind
• Whistler wave generation by halo electrons in the solar wind
• Electron heat flux in the near-Sun environment
• Particle-In-Cell simulation of whistler heat flux instabilities in the solar wind: heat flux regulation and electron halo formation
• Whistler wave occurrence and the interaction with strahl electrons during the first encounter of Parker Solar Probe
• Suprathermal electron strahl widths in the presence of narrow-band whistler waves in the solar wind
• Precision Electron Measurements in the Solar Wind at 1 au from NASA's Wind Spacecraft
• On the role of solar wind expansion as a source of whistler waves: scattering of suprathermal electrons and heat flux regulation in the inner heliosphere
• Whistler waves observed by Solar Orbiter / RPW between 0.5 AU and 1 AU
• Whistler Waves and Electron Properties in the Inner Heliosphere: Helios Observations
• On quasi-parallel whistler waves in the solar wind
• Electron energy partition across interplanetary shocks: III. Analysis
• Whistler instability driven by the sunward electron deficit in the solar wind
• Whistler waves generated inside magnetic dips in the young solar wind: observations of the Search-Coil Magnetometer on board Parker Solar Probe
• The Stability of the Electron Strahl against the Oblique Fast-magnetosonic/Whistler Instability in the Inner Heliosphere