Dielectronic recombination of iron L-shell ions

An experimental program to study low temperature dielectronic recombination (DR) in the iron L-shell ions Fe17+ to Fe23+ is currently in progress at t he TSR heavy-ion storage ring in Heidelberg, Germany L-shell iron ions play an important role in determining the line emission and thermal and ionizat ion structures of cosmic photoionized plasmas. Successful modelling of thes e plasmas requires accurate ionization and recombination rates, particularl y for low temperature DR which is the dominant recombination mechanism for most iron ions in photoionized plasmas. The dependence of DR on the detaile d atomic structure makes it challenging to determine the needed DR rate coe fficients theoretically, especially in many-electron systems. Our systemati c survey of Li- to F-like Fe-ions is designed to produce high-resolution DR spectra which can be used to benchmark theory for ions of increasing compl exity and to provide absolute low-temperature DR rates required in astrophy sics.