Recent Results from Nb₃Sn-Coated Single-cell Cavities Combined with Sample Studies at Jefferson Lab

The critical temperature (~ 18 K) and superheating field (~ 425 mT) of Nb₃Sn are almost twice that of niobium, thereby promising the higher quality factor and accelerating gradient at any given temperature compared to traditional SRF cavities made of niobium. It can enable higher temperature for cavity operation (4 K Vs. 2 K), resulting in significant reduction in both capital and operating cost for the cryoplant. Several single-cell cavities along with witness samples were coated with Nb₃Sn to explore, understand and improve the coating process for betterment of cavity performance. RF measurements of coated cavities combined with material characterization of witness samples were employed to update the coating process. Following some modifications to the existing coating process, we were able to produce Nb₃Sn cavity with quality factor ≥ 2.10¹⁰ for accelerating gradient up to 15 MV/m at 4 K, without any significant Q-slope. In this article, we will discuss recent results from several Nb₃Sn coated single-cell cavities combined with material studies of witness samples.
Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia