RF Measurement and Characterization of European Spallation Source Cavities at UKRI-STFC Daresbury Laboratory and DESY

The Accelerator and Science and Technology Centre (ASTeC) is responsible for delivering 88 High Beta (HB) cavities as part of the European Spallation Source (ESS) facility in Sweden. The bulk Niobium Superconducting Radio Frequency (SRF) cavities operate at 704 MHz. They have been fabricated in industry and are currently being tested at Daresbury Laboratory and Deutsches Elektronen-Synchrotron (DESY). They will then be delivered to Commissariat à l’énergie atomique et aux énergies alternatives (CEA) Saclay, France for integration into cryomodules. To date, 50 cavities have been conditioned and evaluated and 36 cavities have been delivered to CEA. This paper discusses the experiences and testing of the cavities performed to date at both sites