Author: Fonnesu, D.
Paper Title Page
Nb/Cu Coatings Characterization in HiPIMS With Biased Substrate and Application of a Positive Pulse  
  • F. Avino, S. Calatroni, D. Fonnesu, A. Grudiev, P. Naisson, H. Neupert, A.T. Perez Fontenla, T. Richard, G.J. Rosaz, A. Sublet, M. Taborelli
    CERN, Geneva, Switzerland
  In this work, we present results on the characterization of Nb on Cu films obtained in High Power Impulse Magnetron Sputtering (HiPIMS) with a negatively biased substrate, or with a positive pulse after the main negative one [1]. This allows to accelerate the Nb+ atoms towards substrates with small grazing angles of incidence to obtain a dense and defect-free Nb film. Samples reproducing the shape of a 1.3 GHz SRF cavity are coated by varying the timing of the substrate bias with respect to the main HiPIMS. The Nb film residual stress and estimations of the amount of trapped discharge gas (Kr) are also presented. The effect of applying a positive pulse after the main HIPIMS pulse on Nb/Cu samples coated in Ar is further explored. Crystallites size characterization is obtained with X-Ray Diffraction. First SRF properties by measurement of the critical temperature are provided. Preliminary results of Nb/Cu coatings of Cu samples reproducing the real geometry of the Wide Open Waveguide Crab cavity [2] are presented.
[1] F Avino et al., Plasma Sources Sci. Technol., vol. 28 pp. 01LT03, 2019.
[2] A. Grudiev, Proceedings of SRF 2015.
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