Large grain CBMM Nb ingot slices [electronic resource] : An ideal test bed for exploring the microstructure-electromagnetic property relationships relevant to SRF
- Washington, D.C. : United States. Dept. of Energy. High Energy Physics Division, 2015.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy
- Physical Description:
- Article numbers 020,004 : digital, PDF file
- Additional Creators:
- United States. Department of Energy. High Energy Physics Division
United States. Department of Energy. Office of Scientific and Technical Information
- High purity (RRR > 200), large grain (> 5-10 cm) niobium ingot slices have been successfully used to fabricate radio frequency (RF) cavities for particle accelerators. In addition, they offer significantly reduced fabrication cost by eliminating processing steps and furthermore they provide the opportunity to study the influence of individual grain boundaries in SRF Nb. Here we summarize our measurements of grain boundary (GB) effects on the superconducting properties of large grain high purity niobium sheet manufactured by CBMM. We show by magneto-optical (MO) imaging that GBs allow premature flux penetration, but only when they are oriented close to the direction of the magnetic field. However, even low angle GBs produced by minor deformations commensurate with half-cell forming produce localized flux penetration. The transport properties of grain boundaries were investigated by direct transport across them and evidence for preferential vortex flow along the GBs of SRF Nb was observed for the first time. Using transmission electron microscopy (TEM) and micro crystallographic analysis with electron backscattered diffraction (EBSD), we were able to quantitatively characterize surface substructures that can lead to localized thermal breakdown of superconductivity. Important to these studies was the development of sample preparation techniques that made the cut-out single, bi-crystal and tri-crystal Nb coupons as representative as possible of the surface properties of cavities manufactured by standard techniques.
- Published through SciTech Connect.
AIP Conference Proceedings 1687 ISSN 0094-243X AM
Science And Technology Of Ingot Niobium For Superconducting Radio Frequency Applications, Jefferson Lab, VA (United States), 4 Dec 2015.
Zu -Hawn Sung; Peter J. Lee; Anatolii Polyanskii; Shreyas Balachandran; Santosh Chetri; David C. Larbalestier; Mingmin Wang; Christopher Compton; Thomas R. Bieler.
Florida State Univ., Tallahassee, FL (United States)
- Funding Information:
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