Tests at High RF Power of the ESS Medium Beta Cryomodule Demonstrator

International audienceCEA is in charge of the 30 elliptical medium and high-beta cryomodules to be installed in the ESS tunnel in Lund, Sweden. Before launching the assembly of the series cryomodules, CEA developed a medium-beta cryomodule technology demonstrator in a collaboration with IPNO, LASA and ESS. This paper briefly presents the cryomodule assembly and summarizes the main results of the high RF power tests performed in 2018 in a dedicated test stand in CEA Saclay. The main ESS requirements were reached: E_{acc} = 16.7 MV/m in cavities, Pforward = 1.1 MW in power couplers, RF pulses length = 3.6 ms at 14 Hz. The piezo tuners efficiently compensated the Lorentz forces detuning and could stabilize the accelerating field better than 1% over the full length of the expected ESS 2.86 ms beam pulse without any LLRF regulation system. Following this successful validation CEA started the assembly of the first ESS medium-beta series cryomodul

Developments and Progress with ESS Elliptical Cryomodules at CEA-Saclay and IPN-orsay

International audienceCEA Saclay in collaboration with IPN Orsay is in charge of the ESS elliptical cavities cryomodule design, prototyping and series production. Two cryomodule prototypes are being developed and will be tested at CEA Saclay before starting the series production. The main cryomodule design features are first reminded. We present the cavities and couplers test results and the achieved assembly sequences of the first medium beta cavities cryomodule demonstrator M-ECCTD. The progress on the preparation of the CEA cryomodule test station is given. The procurement status and development plan of the second high beta demonstrator H-ECCTD are also reported. Finally we give the components procurement progress and the assembly strategy of the 30 series cry-omodules to be integrated at CEA before delivery to ESS at Lund