Author: Prudnikava, A.L.
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MOPTEV006 Synchrotron XPS Study of Niobium Treated with Nitrogen Infusion 211
  • A.L. Prudnikava, J. Knobloch, O. Kugeler, Y. Tamashevich
    HZB, Berlin, Germany
  • V. Aristov, O. Molodtsova
    DESY, Hamburg, Germany
  • S. Babenkov
    LIDYL, Gif sur Yvette, France
  • A. Makarova
    FUB, Berlin, Germany
  • D. Smirnov
    Technische Universität Dresden, Dresden, Germany
  Processing of niobium cavities with the so-called ni-trogen infusion treatment demonstrates the improve-ment of efficiency and no degradation of maximal accelerating gradients. However, the chemical compo-sition of the niobium surface and especially the role of nitrogen gas in this treatment has been the topic of many debates. While our study of the infused niobium using synchrotron X-ray Photoelectron Spectroscopy (XPS) showed modification of the surface sub-oxides surprisingly there was no evidence of nitrogen con-centration build up during the 120°C baking step, irre-spectively of N2 supply. Noteworthy, that the niobium contamination with carbon and nitrogen took place during a prolonged high-temperature anneal even in a high vacuum condition (10-8-10-9 mbar). Evidently, the amount of such contamination appears to play a key role in the final cavity performance  
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About • Received ※ 21 June 2021 — Revised ※ 13 July 2021 — Accepted ※ 19 August 2021 — Issue date ※ 05 September 2021
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Damage Recovery for SRF Photoinjector Cavities  
  • Y. Tamashevich, A. Frahm, F. Göbel, S. Heling, A. Hellwig, K. Janke, S. Klauke, J. Knobloch, A.N. Matveenko, A. Neumann, H. Plötz, A.L. Prudnikava, S. Rotterdam, M. Schuster, J. Ullrich
    HZB, Berlin, Germany
  Two niobium elliptical 1.3 GHz SRF electron photoinjector cavities were successfully recovered after mechanical inner surface damage. Both injector cavities had deep imprints in critical high surface electric field area around the photoelectric cathode position. The repairing procedure, consisting of surface inspection, mechanical polishing and light chemical etching is described in detail. Subsequent cold RF tests demonstrate complete performance recovery.  
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