Time-Dependent Close-Coupling Calculations of Charge Exchange between Bare Ne and Mg ions and atomic H and He targets at solar wind velocities*

Charge exchange between highly charged ions and neutrals introduces a problematic background source in each astrophysical x-ray observation. For H-like ions produced by charge exchange between bare ions and neutrals the angular momentum states within each n shell are degenerate. While several analytical angular momentum distributions are available (low energy, statistical), the exact distribution of angular momentum states is not yet known, and the most appropriate choice for solar wind velocities (~1 - 5 keV/u) is not apparent. We present nl-resolved CX cross sections for bare Ne and Mg incident on atomic H and He targets calculated using the time-dependent close-coupling (TDCC) approach. We combined our nl-resolved CX cross sections and other atomic data in an x-ray cascade model and compared our synthetic spectra against other work in the literature. At solar wind velocities, we find some similarities between Multi-Channel Landau-Zener (MCLZ) n-resolved cross sections with an applied statistical angular momentum distribution and our TDCC results. We find poorer agreement between TDCC and MCLZ n-resolved cross sections with a low energy l-distribution applied.