Quasilinear Evolution and Perpendicular Ion Heating in the Turbulent Solar Wind

The measured spectrum of kinetic Alfven wave (KAW) fluctuations in the turbulent solar wind plasma is used to calculate the electron and ion distribution functions resulting from quasi-linear diffusion. Quasi-linear diffusion establishes a step-like profile on the distribution function over parallel velocity [1]. The size of ``plateau'' $v_m $, which can be created within the time of travel of solar wind plasma to the Earth $\sim $ 10$^{5}$ s, is estimated for electrons as $v_{me} /v_{te} \sim (10^{-7}t)^{1/6}\sim 0.5$, while for ions $v_{mi} /v_{ti} \sim (10^{-2}t)^{1/7}\sim 3$. In this case the evolution of the ion tail distribution function can be approximated as $f_{tail} \sim t^{-1/7}\exp (-\vert v_z \vert ^7/v_{mi}^7 )$. As a result, the Landau damping of KAW and whistlers in the high beta solar wind plasma is strongly\underline { }diminished. Also the ion tail distribution function is found to be unstable to electromagnetic ion cyclotron (EMIC) waves [2]. These waves pitch angle scatter the parallel component of the ion velocity into the perpendicular velocity. With less than 1{\%} of turbulent magnetic field energy in EMIC waves the perpendicular ion heating can be possible. Supported by ONR. \\[0pt] [1] L. Rudakov \textit{et. al.}, Phys. Plasma, \textbf{18}, 012307 (2011).\\[0pt] [2] L. Rudakov \textit{et. al.}, arxiv.org:physics.plasm-ph:1012.2398v2, (2011b).