Leith, S.; Vogel, M.; Seiler, E.; Ries, R.; Li, Y.; Müller, J.; Tikhonov, D.; Kugeler, O.; Keckert, S.; Sezgin, A. Ö.; Jiang, X.; Butz, B.; Knobloch, J.: The Development of HiPIMS Multilayer SIS Film Coatings on Copper for SRF Applications. In: Kenji Saito ... [Ed.] : SRF2021 : Proceedings of the 20th International Conference on RF Superconductivity, virtuell, 27 June 2021 to 2 July 2021Geneva: JACoW, 2022. - ISBN 978-3-95450-233-2, p. SUPFDV012/1-5
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Abstract:
Abstract In recent years, the use of alternatives to bulk Nb in the fabrication of SRF cavities, including novel materials and/or fabrication techniques, have been extensively explored by the SRF community. One of these new methodologies is the use of a superconductor-insulator-superconductor (SIS) multilayer structure. Typically, these have been envisaged for use with bulk Nb cavities. However, it is conceivable to combine the benefits of SIS structures with the benefits of coated Cu cavities, such as operation at 4.2 K. It is also clear that the use of, so-called, energetic deposition techniques such as high power impulse magnetron sputtering (HiPIMS), provide significant benefits over typical DC magnetron sputtering (MS) coatings, in terms of SRF performance. In light of this, two series of multilayer SIS film coatings, with a Nb-AlN-NbN structure, were deposited onto electropolished OFHC Cu samples, with the use of HiPIMS, in order to determine the efficacy of this approach. This contribution details the development of these coatings and the required optimization of the coating parameters of the separate material systems, through the use of multiple material and superconducting characterization techniques. This research culminated in the deposition of two SIS-film quadrupole resonator (QPR) samples, using the final optimized coating process.