Author: Prudnikava, A.L.
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TUPB111 R&D Activities on Centrifugal Barrel Polishing of 1.3 GHz Niobium Cavities at DESY/University of Hamburg 655
 
  • A.L. Prudnikava, B. Foster, Y. Tamashevich
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • A. Ermakov, B. Foster
    DESY, Hamburg, Germany
  • Y. Tamashevich
    HZB, Berlin, Germany
  
  In this paper the status of research activities at ILC-HiGrade Lab (DESY/University of Hamburg) on Centrifugal Barrel Polishing (CBP) of 1.3 GHz Niobium Cavities is presented. We focus on CBP based on the polishing recipe reported by Fermi National Laboratory and Jefferson Lab*. The aim is to gain a better understanding of the limitations of this technique, detailed characterization of the treated surface after each polishing step using a "coupon" single cell cavity. Plastic deformations upon initial CBP steps, embedded polishing media and residual damage upon final polishing were investigated at different areas of the cavity.
* C. A. Cooper, L. D. Cooley, Supercond. Sci. Technol. 26 (2013) 015011 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB111  
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TUPB113 Surface Characterization of Nitrided Niobium Surfaces 663
 
  • A.L. Prudnikava, B. Foster
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • B. Foster
    DESY, Hamburg, Germany
  • Y. Tamashevich
    HZB, Berlin, Germany
  • Y. Tamashevich
    University of Hamburg, Hamburg, Germany
  
  Thermal treatment of niobium radio frequency cavities in nitrogen atmosphere is employed in ILCLS-II Project in order to improve the quality factor of Nb cavities. A so called "N-infusion" thermal treatment is applied without any post processing*, **, whereas "N-doping" requires the removal of the upper layer of 5-30 um. For better understanding the mechanism of such an improvement, a detailed characterization of the nitrided surface is necessary. Our studies are focused on characterization of the niobium surface subjected to such treatments (surface morphology, nitrogen concentration profile, hardness, phase composition). The sample preparation technique for studying the hydride precipitation in N-Nb system is presented, and current activities on studying of N-infused Nb samples by SQUID and PPMS are briefly discussed.
* A. Grassellino, et al, Supercond. Sci. Technol. 26 (2013) 102001.
** A. Grassellino, arXiv:1701.06077 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB113  
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THPB007 Nitrogen Infusion R&D on Single Cell Cavities at DESY 759
 
  • M. Wenskat, D. Reschke, J. Schaffran
    DESY, Hamburg, Germany
  • A.L. Prudnikava
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  
  A first series of single cell cavities underwent the "Nitrogen Infusion" treatment at DESY. Samples, which were in the furnace together with the cavities, underwent a series of SEM/EDX measurements and showed some unexpected structures. In parallel, the cavity performance deteriorated after the treatment. The furnace pressure and temperature and the residual gases during the treatment were analyzed and the possible cause for the deterioration has been found. Steps to prevent this deterioration in following treatments are discussed and first results are shown.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THPB007  
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