SH025-10
Whistler Heat Flux and Anisotropy Instability in the Solar Wind
Thursday, 10 December 2020: 10:57
Virtual
Ilya Kuzichev, New Jersey Institute of Technology, Center for Solar-Terrestrial Research, Newark, NJ, United States; Space Research Institute RAS, Moscow, Russia, Ivan Vasko, Space Science Lab, UC Berkeley, Berkeley, CA, United States, A. Rualdo Soto-chavez, Syntek Technologies, Inc, Fairfax, VA, United States, Stuart D Bale, University of California Berkeley, Space Sciences Laboratory, Berkeley, CA, United States and Anton Artemyev, University of California Los Angeles, Earth, Planetary, and Space Sciences, Los Angeles, CA, United States
Abstract:
The electron heat flux is one of the leading terms in energy flow processes in the collisionless or weakly-collisional solar wind plasma. The very first observations demonstrated that the collisional Spitzer-Hӓrm law could not describe the heat flux in the solar wind well. In particular, in-situ observations at 1AU showed that the heat flux was suppressed below the collisional value. Different mechanisms of the heat flux regulation in the solar wind were proposed. One of these possible mechanisms is the wave-particle interaction with whistler-mode waves produced by the so-called whistler heat flux instability. This instability operates in plasmas with at least two counter-streaming electron populations. Recent observations indicated that the WHFI operates in the solar wind producing predominantly quasi-parallel whistler waves with the amplitudes up to several percent of the background magnetic field.
Simulations of the nonlinear evolution of WHFI demonstrated that parallel whistler waves are incapable of suppressing the heat flux. In this study, we consider the combined whistler heat flux and anisotropy instability (WHFAI). Anti-parallel waves driven by temperature anisotropy waves would interact with a substantial fraction of halo electrons carrying the heat flux. Thus, they could influence the heat flux more significantly than parallel waves. We have performed PIC simulations of WHFAI and studied how the wave properties depend on the electron distribution parameters. Our calculations demonstrate that anti-parallel waves can decrease the heat flux. This indicates that the whistler waves generated via combined anisotropy and whistler heat flux instability might contribute to regulation of the heat flux in the solar wind.
The work was supported by the NSF Grant No. 1502923 and the NASA Van Allen Probes RBSPICE instrument project provided by JHU/APL subcontract 131803 under NASA prime contract NNN06AA01C. We acknowledge high-performance computing support from Cheyenne (doi:10.5065/D6RX99HX) provided by NCAR's Computational and Information Systems Laboratory, sponsored by the National Science Foundation.
