Observations of the ultraviolet and x-ray brightness profiles and cooling rates of Kr and Ar in magnetically confined fusion plasmas

The spatial brightness profiles of Ar and Kr ions have been measured during a set of experiments in which these gases were puffed into FTU (Frascati Tokamak Upgrade) and Alcator C-Mod tokamak plasmas. These profiles were measured by spatially scanning photometrically calibrated vuv and x-ray spectrometers covering 3 to 1700 Å on a shot to shot basis. Several simulations of these profiles were performed using the multiple ionization state transport (MIST) code to validate the atomic physics rates used to determine the charge state distribution in the plasmas. A comparison of two sets of atomic physics rates was made. The chosen rates were the original rates in MIST and the more accurate ionization/recombination rate coefficients from the HULLAC atomic code and the current compilations by Mazzotta. The simulations with the more accurate rates could correctly predict the brightness profiles. The simulations with the older rates adequately predicted the Ar brightness profiles but did not accurately predict those of Kr. The inclusion of the excitation autoionization rates which were absent from the MIST code had the most profound effect on the simulated charge state distributions.