Recombination and Ionization Measurements at the Heidelberg Heavy Ion Storage Ring TSR

Knowledge of the charge state distribution (CSD) of astrophysical plasmas is important for the interpretation of spectroscopic data. To accurately calculate CSDs, reliable rate coefficients are needed for dielectronic recombination (DR), which is the dominant electron-ion recombination mechanism for most ions, and for electron impact ionization (EII). We are carrying out DR and EII measurements of astrophysically important ions using the TSR storage ring at the Max-Plank-Institute for Nuclear Physics in Heidelberg, Germany. Storage ring measurements are largely free of the metastable contamination found in other experimental geometries, resulting in more unambiguous DR and EII reaction rate measurements. The measured data can be used in plasma modelling as well as for benchmarking theoretical atomic calculations.