Fonnesu, D.; Chyhyrynets, A.; Ford, D.; Keckert, S.; Knobloch, J.; Kramer, F.; Kugeler, O.; Lazzari, M.; Marcomato, G.; Curci, I.; Proslier, T.; Wenskat, M.; Zubtsivskii, A.; Pira, C.: Development of Nb3Sn coatings on copper at INFN-LNL. In: Lin Bian (IHEP) ... [Ed.] : Proceedings of the 22nd International Conference on RF Superconductivity : SRF2025 : Tokyo, RIKEN Nishina Center in Wako, Japan from 21–26 September, 2025Geneve: JACoW, 2025. - ISBN 978-3-95450-256-1, p. THA02/1-7
10.18429/JACoW-SRF2025-THA02
Open Access Version
Abstract:
DEVELOPMENT OF Nb3Sn COATINGS ON COPPER AT INFN-LNL∗ D. Fonnesu† 1, E. Chyhyrynets1, D. Ford1, S. Keckert2, J. Knobloch2,6, F. Kramer2, O. Kugeler2, M. Lazzari1, G. Marconato3, I. Curci4, T. Proslier5, M. Wenskat3,7, A. Zubtsovskii6, C. Pira1 1INFN National Institute for Nuclear Physics - Legnaro National Laboratories, Legnaro, Italy 2HZB Helmholtz-Zentrum Berlin for Materials and Energy, Berlin, Germany The successful development of Nb3Sn/Cu coatings for the SRF cavities of next generation particle accelerators would result in the reduction of the needed cryogenic power by a factor 3 with respect to what normally needed for bulk Nb cavities, while maintaining operation at 4.5 K. In the frame- work of the I.FAST and ISAS collaborations, research activ- ities are carried out at INFN-LNL to develop new technolo- gies for the application of Nb3Sn on Cu, including seamless spinning of cavity prototypes, surface chemical preparation, cavity coating and testing. At the same time, an optimized recipe for Nb3Sn films deposited via DCMS has been es- tablished on flat samples and is discussed in this work. The recipe delivers films showing a 𝑇c ≃ 17 K, at deposition temperatures ≤ 650 °C , on a Cu substrate pre-coated with a 30 μm -thick buffer layer of Nb. The deposition recipe has been validated on bulk Nb by measuring its RF properties on a QPR sample, with the results being also discussed in this work. A surface resistance of 23 nΩ at 4.5 K and 20 mT is measured, which corresponds to a 𝑄0 about 5 times larger than the baseline specification for the LHC Nb/Cu cavities and already fulfills the requirements for the FCC-ee. Finally, updates on the activities toward the scalability of the coating recipe to the 1.3 GHz elliptical cavity prototype are given, and the perspectives for further coating recipe refinemenz are discussed.