Author: Balachandran, S.
Paper Title Page
WEZE5 Magnetic Flux Expulsion in Superconducting Radio-Frequency Niobium Cavities Made from Cold Worked Niobium 611
  • B.D. Khanal
    ODU, Norfolk, Virginia, USA
  • S. Balachandran, P.J. Lee
    NHMFL, Tallahassee, Florida, USA
  • S. Chetri
    ASC, Tallahassee, Florida, USA
  • P. Dhakal
    JLab, Newport News, Virginia, USA
  Trapped residual magnetic field during the cool down of superconducting radio frequency (SRF) cavities is one of the primary sources of RF residual losses leading to lower quality factor. Historically, SRF cavities have been fabricated from high purity fine grain niobium with grain size ~50 to 100 µm as well as large grain with grain size of the order of few centimeters. Non-uniform recrystallization of fine-grain Nb cavities after the post fabrication heat treatment leads to higher flux trapping during the cool down, and hence the lower quality factor. We fabricated two 1.3 GHz single cell cavities from cold-worked niobium from different vendors and processed along with cavities made from SRF grade Nb. The flux expulsion and flux trapping sensitivity were measured after successive heat treatments in the range 800 to 1000°C. The flux expulsion from cold-worked fine-grain Nb cavities improves after 800°C/3h heat treatments and it becomes similar to that of standard fine-grain Nb cavities when the heat treatment temperature is higher than 900°C.  
slides icon Slides WEZE5 [2.029 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEZE5  
About • Received ※ 01 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 31 August 2022
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