Journals of Accelerator Conferences Website (JACoW)

JACoW is a publisher in Geneva, Switzerland that publishes the proceedings of accelerator conferences held around the world by an international collaboration of editors.

URLhttps://doi.org/10.18429/JACoW-NAPAC2025-THYN01
TitleHow nitrogen and oxygen shape SRF cavity performance
Authors
  • H. Hu
    University of Chicago
  • D. Bafia
    Fermi National Accelerator Laboratory
  • Y. Kim
    University of Chicago, Fermi National Accelerator Laboratory
AbstractNitrogen and oxygen-based surface treatments have revolutionized the performance of superconducting radiofrequency (SRF) cavities, enabling them to reach higher gradients and lower losses. However, the exact mechanisms by which these treatments improve cavity performance remain largely unknown. This work provides new insights into the role of nitrogen and oxygen in SRF cavity performance by using time-of-flight secondary ion mass spectrometry (TOF-SIMS) to precisely quantify the concentrations and depth profiles of these impurities within niobium cutouts. We correlate these impurity profiles with detailed cavity performance measurements, including surface resistance and quality factor, and compare our findings with predictions from BCS theory. The results demonstrate that while both nitrogen and oxygen enhance performance, ten times more oxygen is required to achieve the same reduction in BCS resistance as interstitial nitrogen. We present a potential model in which the observed variation arises from nitrogen's greater effectiveness in trapping hydrogen, thus reducing the formation of niobium hydrides and enhancing superconducting gap.
Paperdownload: THYN01.pdf
CiteBibTeX, LaTeX, Text/Word, RIS, EndNote
Conference6th North American Particle Accel. Conf. (NAPAC2025)
Series
LocationSacramento, CA, USA
Date10-15 Aug 2025
PublisherJACoW Publishing, Geneva, Switzerland
Editorial BoardTor O. Raubenheimer (SLAC), Roark A. Marsh (LLNL), Eric Prebys (UC Davis), Ling Wang (MSU), Petr M. Anisimov (LANL), Kip Bishofberger (LANL), Gustavo Bruno (ANL), Zhichu Chen (SARI), Jan Chrin (PSI), Kelly Jaje (ANL), Jaeyu Lee (POSTECH), Magdalena Montes-Loera (SLAC), Mary Saethre (PHENOTYPE), Tasha Summers (SLAC), Kent Wootton (ANL)
Online ISBN978-3-95450-261-5
Online ISSN2673-7000
Received13 August 2025
Revised13 August 2025
Accepted14 August 2025
Issued28 January 2026
DOI10.18429/JACoW-NAPAC2025-THYN01
Pages932-935