Veröffentlichungen und Präsentationen

Niobium-3-tin (\nbsn) has emerged as a promising alternative to bulk niobium for superconducting radio frequency (SRF) accelerator cavities, due to its higher critical temperature and lower surface resistance. This study focuses on optimizing the tin vapor diffusion process to enhance coating uniformity and superconducting performance in a 1.3 GHz single-cell Nb cavity. Nb coupon samples were strategically placed at multiple locations along the interior of the cavity to monitor local variations in coating growth. By systematically varying the coating temperature (1100-1200 ° C) and duration (75-150 min), we investigated their combined influence on film thickness, surface morphology, and chemical uniformity. The experimentally measured thickness profiles, obtained via cross-sectional SEM and EDS analysis, were directly compared with finite-element vapor transport simulations, revealing strong spatial dependence of Sn flux and coating growth kinetics along the cavity length. Both experimental and simulation results indicate that coating thickness decreases from the high-flux regions near the tin source toward the cavity equator, consistent with diffusion-limited Sn transport. Lowering the coating temperature reduced the roughness of the surface but required careful optimization to avoid incomplete coverage. These findings provide quantitative insight into the spatial and temporal evolution of Nb₃Sn coatings, guiding future process refinements to achieve uniform, high-quality films and improved SRF cavity performance.