On quasi-parallel whistler waves in the solar wind
Document Type
Article
Publication Date
8-1-2020
Abstract
Recent simulations showed that the whistler heat flux instability, which presumably produces the most of quasi-parallel coherent whistler waves in the solar wind, is not efficient in regulating the electron heat conduction. In addition, recent spacecraft measurements indicated that some fraction of coherent whistler waves in the solar wind may propagate anti-parallel to the electron heat flux, being produced due to a perpendicular temperature anisotropy of suprathermal electrons. We present the analysis of properties of parallel and anti-parallel whistler waves unstable at electron heat fluxes and temperature anisotropies of suprathermal electrons typical of the pristine solar wind. Assuming the electron population consisting of counterstreaming dense thermal core and tenuous suprathermal halo populations, we perform a linear stability analysis to demonstrate that anti-parallel whistler waves are expected to have smaller frequencies, wave numbers, and growth rates compared to parallel whistler waves. The stability analysis is performed over a wide range of parameters of core and halo electron populations. Using the quasi-linear scaling relation, we show that anti-parallel whistler waves saturate at amplitudes of one order of magnitude smaller than parallel whistler waves, which is about 10 - 3 B 0 in the pristine solar wind. The analysis shows that the presence of anti-parallel whistler waves in the pristine solar wind is more likely to be obscured by turbulent magnetic field fluctuations because of lower frequencies and smaller amplitudes compared to parallel whistler waves. The presented results will also be valuable for numerical simulations of the electron heat flux regulation in the solar wind.
Identifier
85089874516 (Scopus)
Publication Title
Physics of Plasmas
External Full Text Location
https://doi.org/10.1063/5.0003401
e-ISSN
10897674
ISSN
1070664X
Issue
8
Volume
27
Recommended Citation
Vasko, I. Y.; Kuzichev, I. V.; Artemyev, A. V.; Bale, S. D.; Bonnell, J. W.; and Mozer, F. S., "On quasi-parallel whistler waves in the solar wind" (2020). Faculty Publications. 5134.
https://digitalcommons.njit.edu/fac_pubs/5134
