Solar Wind Electron Scattering by Kinetic Instabilities and Whistler Turbulence

Abstract:

The expansion of the solar wind away from the Sun drives electron velocity distributions

away from the thermal Maxwellian form, yielding distributions near 1 AU which typically

can be characterized as consisting of three anisotropic components: a more dense, relatively cool

core, a relatively tenuous , relatively warm halo and a similarly tenuous, warm strahl.

Each of these nonthermal components are

potential sources of kinetic plasma instabilities; the enhanced waves from each

instability can scatter the electrons, acting to reduce the various anisotropies and

making their overall velocity distribution more nearly (but not completely) thermal.

In contrast, simulations are demonstrating that the forward decay of whistler

turbulence can lead to the development of a T_||> T_perp electron anisotropy.

This presentation will review linear theories of electron-driven kinetic instabilities

(following the presentation by Daniel Verscharen at the 2015 SHINE Workshop),

and will further consider the modification of electron velocity distributions as

obtained from particle-in-cell simulations of such instabilities

as well as from the decay of whistler turbulence.