ESS Prototype Cavities Developed at CEA Saclay

CEA-Saclay has developed and manufactured 11 elliptical cavities for the European Spallation Source (ESS). A reliable manufacturing and preparation sequence (bulk buffer chemical polishing, heat treatment, flash buffer chemical polishing) has been developed. Latest results on the high beta model are reported and compared to the one of other cavities that have followed the same preparation. The five cavities presented here overpass the target perfor-mance values set by ESS.