After winding, the seventh and last coil of FRESCA2 left Saclay in June 2019 in its reaction mould, putting an end to Irfu's activity on this project, which began in 2009 in collaboration with CERN. This type 3-4 coil is a spare coil, which, after reaction, instrumentation and impregnation at CERN, will join its type 1-2 sister on CERN shelves.
In a first step, the FRESCA2 dipole, a 100 mm Nb3Sn dipole magnet tested at CERN, had reached a field of 13.3 T (see highlight of 20/09/2017). A new series of tests in April 2018, after modifying the mechanical preloading of the magnet, allowed the FRESCA2 dipole to reach 14.6 T at a temperature of 1.9 K, representing a new field record for a dipole of this aperture. During these tests, the stability of its operation was validated at 14.4 T at 1.9 K, and at 13.6 T at 4.5 K respectively. The dipole has been qualified: it will now be able to be used as a test station to accommodate, in particular, tests of small magnets made from high temperature superconductors.
After more than 5 years of development, including 6 months of integration work of the 12,000 separate components to a complete cryomodule, the CEA-Irfu has just validated the technology of this complex system that reached the nominal ESS accelerating field in the 4 superconducting accelerating cavities.
At the limits of technology, this is the first time that such an intense accelerating field, maintained over such long pulse durations and with such high RF power, has been measured in superconducting cavities installed in a complete cryomodule.
This key step makes it possible to start the production phase of the 30 cryomodules that France is to deliver to the ESS research infrastructure, which will be operational in Sweden in 2023. This serial integration will begin in January 2019 under the supervision of Irfu with the contribution of the company B&S France and should be completed in 2022.