Heavy ion acceleration in the divergent solar wind

Abstract

We study the heavy ion acceleration due to cyclotron interaction with both right‐ and left‐hand polarized MHD waves propagating along the magnetic field in the outward direction in the divergent solar wind. It is shown in test‐particle approximation that heavy ions can overcome the gap between the maximum resonant velocity for left‐handed waves and minimum resonant velocity for right‐handed waves and acquire the average parallel velocity on the order of local Alfven speed relative to the protons.