EGU21-10198
https://doi.org/10.5194/egusphere-egu21-10198
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Particle-In-Cell simulations of resonant interactions between whistler waves and electrons in the near-Sun solar wind: scattering of the strahl into the halo and heat flux regulation.

Alfredo Micera1,2, Andrei Zhukov1,3, Rodrigo A. López4, Maria Elena Innocenti5, Marian Lazar2,5, Elisabetta Boella6,7, and Giovanni Lapenta2
Alfredo Micera et al.
  • 1Royal Observatory of Belgium, Brussels, Belgium
  • 2KU Leuven, Leuven, Belgium
  • 3Moscow State University, Moscow, Russia
  • 4Universidad de Santiago de Chile, Santiago, Chile
  • 5Ruhr-Universität Bochum, Bochum, Germany
  • 6Lancaster University, Lancaster, UK
  • 7Daresbury Laboratory, Warrington, UK

Electron velocity distribution functions, initially composed of core and strahl populations as typically encountered in the near-Sun solar wind and as recently observed by Parker Solar Probe, have been modeled via fully kinetic Particle-In-Cell simulations. It has been demonstrated that, as a consequence of the evolution of the electron velocity distribution function, two branches of the whistler heat flux instability can be excited, which can drive whistler waves propagating in the direction parallel or oblique to the background magnetic field. First, the strahl undergoes pitch-angle scattering with oblique whistler waves, which provokes the reduction of the strahl drift velocity and the simultaneous broadening of its pitch angle distribution. Moreover, the interaction with the oblique whistler waves results in the scattering towards higher perpendicular velocities of resonant strahl electrons and in the appearance of a suprathermal halo population which, at higher energies, deviates from the Maxwellian distribution. Later on, the excited whistler waves shift towards smaller angles of propagation and secondary scattering processes with quasi-parallel whistler waves lead to a redistribution of the scattered particles into a more symmetric halo. All processes are accompanied by a significant decrease of the heat flux carried by the strahl population along the magnetic field direction, although the strongest heat flux rate decrease is simultaneous with the propagation of the oblique whistler waves.

How to cite: Micera, A., Zhukov, A., López, R. A., Innocenti, M. E., Lazar, M., Boella, E., and Lapenta, G.: Particle-In-Cell simulations of resonant interactions between whistler waves and electrons in the near-Sun solar wind: scattering of the strahl into the halo and heat flux regulation., EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10198, https://doi.org/10.5194/egusphere-egu21-10198, 2021.

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