Author: Stierle, A.
Paper Title Page
MOP023 Nitrogen Infusion Sample R&D at DESY 77
SUSP002   use link to see paper's listing under its alternate paper code  
  • C. Bate, A. Dangwal Pandey, A. Ermakov, B. Foster, T.F. Keller, D. Reschke, J. Schaffran, S. Sievers, N. Walker, H. Weise, M. Wenskat
    DESY, Hamburg, Germany
  • W. Hillert
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • G.D.L. Semione, V. Vonk
    DESY Nanolab, FS-NL, Hamburg, Germany
  • A. Stierle
    University of Hamburg, Hamburg, Germany
  The European XFEL continuous wave upgrade requires cavities with reduced surface resistance (high Q-values) for high duty cycle while maintaining high accelerating gradient for short-pulse operation. A possible way to meet the requirements is the so-called nitrogen infusion procedure. However, a fundamental understanding and a theoretical model of this method are still missing. The approach shown here is based on sample R&D, with the goal to identify key parameters of the process and establish a stable, reproducible recipe. To understand the underlying processes of the surface evolution, which gives improved cavity performance, advanced surface analysis techniques (e.g. SEM/EDX, TEM, XPS, TOF-SIMS) are utilized. Additionally, a small furnace just for samples was set up to change and explore the parameter space of the infusion recipe. Results of these analyses, their implications for the cavity R&D and next steps are presented.  
poster icon Poster MOP023 [3.759 MB]  
DOI • reference for this paper ※  
About • paper received ※ 23 June 2019       paper accepted ※ 30 June 2019       issue date ※ 14 August 2019  
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Surface Analysis of Niobium After Thermal/Gas Treatments via Samples - Review  
  • A. Dangwal Pandey, T.F. Keller, H. Noei, D. Reschke, J. Schaffran, G.D.L. Semione, V. Vonk, H. Weise, M. Wenskat
    DESY, Hamburg, Germany
  • C. Bate, A. Stierle
    University of Hamburg, Hamburg, Germany
  Thermal treatments of SRF Nb cavities - including the well-established 120°C bake and the recently reported N-infusion - are shown to improve the cavity performance significantly; however, the underlying physical phenomenon is not fully understood. A short review will be presented on surface characterization of niobium material subjected to various thermal and gas exposure protocols and how the findings correlate with observed SRF properties. Moreover, recent results obtained on single-crystal Nb samples - heated in different vacuum environments and characterised by means of X-ray photoelectron spectroscopy and grazing-incidence X-ray diffraction, electron microscopy, energy dispersive X-ray spectroscopy and time-of-flight secondary ion mass spectroscopy will be discussed.  
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