Ion Charge States in a Time-Dependent Wave-Turbulence-Driven Model of the Solar Wind

Ion fractional charge states, measured in situ in the heliosphere, depend on the properties of the plasma in the inner corona. As the ions travel outward in the solar wind and the electron density drops, the charge states remain essentially unaltered or frozen in. Thus they can provide a powerful constraint on heating models of the corona and acceleration of the solar wind. We have implemented non-equilibrium ionization calculations into a 1D wave-turbulence-driven (WTD) hydrodynamic solar wind model and compared modeled charge states with the Ulysses 1994-1995 in situ measurements. We have found that modeled charge-state ratios of C6+/C5+ and O7+/O6+, among others, were too low compared with Ulysses measurements. However, a heuristic reduction of the plasma flow speed has been able to bring the modeled results in line with observations, though other ideas have been proposed to address this discrepancy. We discuss implications of our results and the prospect of including ion charge-state calculations into our 3D MHD model of the inner heliosphere.