RF test on coated resonant cavity

The goal of D9.2 is to coat and test a resonant cavity with an alternative material to Niobium with a Q₀ > 10E9 at 4.2 K and 1.3 GHz. In Task 9.2, two lines of development were carried out to achieve the goal: the first concerning the copper cavities serving as substrates, and the second focusing on the deposition set-ups. For both, alternative solutions had to be identified compared to what was originally foreseen in the proposal, due both to technological challenges that emerged during the R&D phase of task 9.3 and to the loss of key partners.

In this document are reported the advancement in seamless Cu cavities production and polishing, the description of the two Nb₃Sn coating system designed and built in INFN and UKRI, the protocol adopted for the first 1.3 GHz Nb₃Sn cavity coated by PVD in Europe and finally, the SRF performances of Nb₃Sn coatings are reported and discussed.