Orateur
Description
The suprathermal electrons in the solar wind are categorized in two different
populations. The halo is nearly isotropic while the strahl is highly anisotropic.
Following previous studies, we characterize the strahl by its pitch angle width.
We aim at finding correlations between this quantity and local plasma or mag-
netic field parameters, and to compare these correlations with prediction from
diffusion models for solar wind electrons. For this, we used data from the SPAN
and FIELDS instruments of the Parker Solar Probe mission, during 17 approaches.
We show that the correlations between the strahl PAW and the density and
the energy are in a relatively good agreement with a pitch angle diffusion due
to the Coulomb collisions at distances from the Sun smaller than 30 Rs at en-
ergies around 300 eV. At larger distances, we show that the pitch-angle width
cannot be explained by Coulomb scattering. We discuss the likely causes of the
non-coulomb strahl broadening, from whistler waves or background magnetic
fluctuations.
| Astrophysics Field | Plasma, Electrons, Heliosphere |
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