Stanislav Boldyrev

The solar wind contains fast, suprathermal electrons that stream from the sun along the Parker-spiraled magnetic field lines. These electrons experience very weak Coulomb collisions and they get collimated in a narrow beam (strahl). When Coulomb collisions are not efficient, the strahl is broadened by interactions with plasma turbulence. We argue that at high energies, the strahl electrons can efficiently interact with whistler waves. We demonstrate how pitch-angle scattering by whistler turbulence can be incorporated into the kinetic theory of electron strahl broadening. By measuring the strahl width, one can estimate the parameters of whistler turbulence.