Fluxon-Induced Losses in Niobium Thin-Film Cavities Revisited

Long standing data from niobium thin-film accelerating cavities will be revisited and analyzed by a modified London model of radio-frequency (RF) superconductivity. First, the applicability of this model is explored using the data of the Bardeen-Cooper-Schrieffer (BCS) surface resistance and its dependence on the RF magnetic field, temperature, and mean free path. Second, the RF losses from the trapped magnetic flux are analyzed with regard to their dependence on these same parameters.