Author: Valizadeh, R.
Paper Title Page
THFUA3
 Material and Superconducting Properties of NbTiN/AlN Multilayer Films  
 
  • A-M. Valente-Feliciano, D.R. Beverstock, C.E. Reece
    JLab, Newport News, Virginia, USA
  • C.Z. Antoine
    CEA-DRF-IRFU, France
  • S. Keckert, O. Kugeler, D.B. Tikhonov
    HZB, Berlin, Germany
  • M.J. Kelley
    The College of William and Mary, Williamsburg, Virginia, USA
  • R. Valizadeh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and DARPA-BAA MIPR No. HD0011728910
In the pursuit of increasing the range of surface magnetic fields sustainable in SRF cavities, new standards in quality of thin multi-layer superconductor/insulator/superconductor (SIS) structures are being achieved. With the synergistic development of multilayered metamaterials based on 3 to 1 nm NbTiN and AlN films, the interface between films is improved. Based on bulk film values, the maximum magnetic field contour plot is also established for NbTiN to guide the choice of each layer thickness and quickly converge to optimized SIS structures. The delayed DC flux entry is measured for standalone NbTiN films and multilayer stacked structures on ideal substrates and Nb substrates. Some SIS structures along with standalone NbTiN films have been deposited on Nb and their superconducting properties and RF surface impedance are evaluated. 		 
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THP041 Impact of the Cu Substrate Surface Preparation on the Morphological, Superconductive and RF Properties of the Nb Superconductive Coatings 935
 
  • C. Pira, E. Chyhyrynets
    INFN/LNL, Legnaro (PD), Italy
  • C.Z. Antoine
    CEA-IRFU, Gif-sur-Yvette, France
  • X. Jiang, S.B. Leith, M. Vogel
    University Siegen, Siegen, Germany
  • A. Katasevs, J. Kaupužs, A. Medvids, P. Onufrijevs
    Riga Technical University, Riga, Latvia
  • O. Kugeler
    HZB, Berlin, Germany
  • O.B. Malyshev, R. Valizadeh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • R. Ries, E. Seiler
    Slovak Academy of Sciences, Institute of Electrical Engineering, Bratislava, Slovak Republic
  • A. Sublet
    CERN, Meyrin, Switzerland
  
  Funding: This project has received funding from the European Union’s Horizon 2020 Research and Innovation programme under Grant Agreement No 730871.
Nowadays, one of the main issues of the superconducting thin film resonant cavities is the Cu surface preparation. A better understanding of the impact of copper surface preparation on the morphological, superconductive (SC) and RF properties of the coating, is mandatory in order to improve the performances of superconducting cavities by coating techniques. ARIES H2020 collaboration includes a specific work package (WP15) to study the influence of Cu surface polishing on the SRF performances of Nb coatings that involves a team of 8 research groups from 7 different countries. In the present work, a comparison of 4 different polishing processes for Cu (Tumbling, EP, SUBU, EP+SUBU) is presented through the evaluation of the SC and morphological properties of Nb thin film coated on Cu planar samples and QPR samples, polished with different procedures. Effects of laser annealing on Nb thin films have also been studied. Different surface characterizations have been applied: roughness measurements, SEM, EDS, XRD, AFM, and thermal and photo-stimulated exoelectrons measurements. SC properties were evaluated with PPMS, and QPR measurements will be carry out at HZB in the beginning of 2019. 		 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP041  
About • paper received ※ 23 June 2019       paper accepted ※ 05 July 2019       issue date ※ 14 August 2019  
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