Berlin 2024 – wissenschaftliches Programm
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AKBP: Arbeitskreis Beschleunigerphysik
AKBP 9: SRF-Cavities -Materials and Methods
AKBP 9.2: Vortrag
Mittwoch, 20. März 2024, 15:15–15:30, E 020
Magnetic Characterization of PEALD Coated Thin Films for SRF Cavity Research — •Lea Preece1, Isabel Gonzalez Diaz-Palacio1, Getnet Deyu1, Robert Blick1, Robert Zierold1, Daniel Turner2, Alick Macpherson2, Marc Wenskat1, and Wolfgang Hillert1 — 1Universität Hamburg, Hamburg, Germany — 2CERN, Geneva, Switzerland
Superconducting radio frequency (SRF) bulk niobium cavities approach their performance limit. Therefore, current research explores novel approaches, such as coating the inner cavity walls with superconductor-insulator-superconductor (SIS) multilayers. Herein, we report on the unprecedented in-depth magnetic characterization of SIS samples deposited by plasma-enhanced atomic layer deposition (PEALD). The aim of this study is to assess the quality of PEALD-based SIS films and foresee potential improvements in cavity performance. The research involves several steps. First, the critical temperature (TC) and the lower critical magnetic field (HC1) of SIS-coated Nb and Si samples are measured via electrical transport and vibrating sample magnetometry. Then, the magnetic flux expulsion of SIS-coated Nb samples is being investigated in cooperation with CERN. Moreover, the London penetration depth (λL) of a coated Nb sample is derived. Finally, the lower critical magnetic field HC1 of SIS-coated Nb samples with various thicknesses of the superconducting top layer is determined by performing third-harmonic voltage measurements with local magnetometry. All these results will be tested against theoretical predictions for SIS multilayer films.
Keywords: SRF; Niobium; Cavity; Thin Films; SIS