  We present a further investigation into the increased ionization observed in
element charge states in the fast solar wind compared to its coronal hole
source regions. Once ions begin to be perpendicularly heated by ion cyclotron
waves and execute large gyro-orbits, density gradients in the flow can excite
lower hybrid waves that then damp by heating electrons in the parallel
direction. We give further analysis of charge state data from polar coronal
holes at solar minimum and maximum, and also from equatorial coronal holes. We
also consider further the damping of lower hybrid waves by ions and the effect
of non-Maxwellian electron distribution functions on the degree of increased
ionization, both of which appear to be negligible for the solar wind case
considered here. We also suggest that the density gradients required to heat
electrons sufficiently to further ionize the solar wind can plausibly result
from the turbulent cascade of MHD waves.
