Author: Jiang, X.
Paper Title Page
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.
 
poster icon Poster THP041 [3.196 MB]  
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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THP042 Initial Results from Investigations into Different Surface Peparation Techniques of OFHC Copper for SRF Applications 941
 
  • S.B. Leith, X. Jiang, Z. Khalil, A.S.H. Mohamed, M. Vogel
    University Siegen, Siegen, Germany
 
  Funding: This work forms part of the EASITrain research programme. This Marie Sklodowska-Curie Action (MSCA) Innovative Training Networks (ITN) has received funding from the European Union’s H2020 Framework Programme under Grant Agreement no. 764879
As part of efforts to improve the performance of thin film coated accelerating cavities, improvement of the topography of the surface of copper is being pursued. This is known to strongly affect the properties of the deposited superconducting thin film. This study focuses on determining the optimal procedure to enhance homogeneity and smoothness of the copper surface. OFHC copper substrates have been processed using mechanical polishing (MP), chemical polishing (CP) and electropolishing (EP) procedures as well as a combina-tion thereof. The parameters of each of the procedures have been tested and optimised to produce the smoothest surface possible. The resulting samples have been analysed using a scanning electron microscope, a laser profilometer and a confocal microscope. Results indicate the superior per-formance of electrochemical polishing over chemical polishing in terms of planarization efficiency, while a combination of mechanical polishing followed by electropolishing provides the most homogeneous and smooth surface when utilising the critical current density of the electrolyte.
 
poster icon Poster THP042 [1.190 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP042  
About • paper received ※ 22 June 2019       paper accepted ※ 29 June 2019       issue date ※ 14 August 2019  
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THP043 Deposition Parameter Effects on Niobium Nitride (NbN) Thin Films Deposited Onto Copper Substrates with DC Magnetron Sputtering 945
SUSP008   use link to see paper's listing under its alternate paper code  
 
  • S.B. Leith, X. Jiang, M. Vogel
    University Siegen, Siegen, Germany
  • R. Ries, E. Seiler
    Slovak Academy of Sciences, Institute of Electrical Engineering, Bratislava, Slovak Republic
 
  Funding: The EASITrain project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant No 764879.
As part of efforts to improve the performance of SRF cavities, to that prescribed by future operating requirements, alternative materials are currently being investigated. NbN is one of the alternatives under investigation to provide these better performance figures. In this contribution, a summary of results from an investigation into DC magnetron sputtered NbN thin films deposited onto copper substrates is presented. The copper substrates were prepared using a mechanical polishing process, followed by a chemical etching process. The NbN films were prepared in a large scale commercial coating system. A high and low value for the substrate temperature, process pressure, bias voltage, cathode power, nitrogen gas percentage, and the working gas type, using either Argon or Krypton, constitute the parameters of this study. The base pressure of the system prior to deposition was 5x107 hPa for all coatings. The resulting films have been characterised using various surface characterisation methods to determine the effects of the deposition parameters during the film growth process. The deposition parameters have been optimised based on the characterisation results.
 
poster icon Poster THP043 [1.169 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP043  
About • paper received ※ 23 June 2019       paper accepted ※ 29 June 2019       issue date ※ 14 August 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)