Ion Charge States in the Fast Solar Wind: New Data Analysis and Theoretical Refinements

We present a further investigation into the increased ionization observed inelement charge states in the fast solar wind compared to its coronal holesource regions. Once ions begin to be perpendicularly heated by ion cyclotronwaves and execute large gyro-orbits, density gradients in the flow can excitelower hybrid waves that then damp by heating electrons in the paralleldirection. We give further analysis of charge state data from polar coronalholes at solar minimum and maximum, and also from equatorial coronal holes. Wealso consider further the damping of lower hybrid waves by ions and the effectof non-Maxwellian electron distribution functions on the degree of increasedionization, both of which appear to be negligible for the solar wind caseconsidered here. We also suggest that the density gradients required to heatelectrons sufficiently to further ionize the solar wind can plausibly resultfrom the turbulent cascade of MHD waves.Comment: 27 pages, accepted by Ap