Large grain CBMM Nb ingot slices: An ideal test bed for exploring the microstructure-electromagnetic property relationships relevant to SRF

Zu Hawn Sung, Peter J. Lee, Anatolii Polyanskii, Shreyas Balachandran, Santosh Chetri, David C. Larbalestier, Mingmin Wang, Christopher Compton, Thomas R. Bieler

    Research output: ResearchConference contribution

    Abstract

    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. 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 cutout single, bi-crystal and tri-crystal Nb coupons as representative as possible of the surface properties of cavities manufactured by standard techniques.

    LanguageEnglish (US)
    Title of host publicationScience and Technology of Ingot Niobium for Superconducting Radio Frequency Applications
    PublisherAmerican Institute of Physics Inc.
    Volume1687
    ISBN (Electronic)9780735413344
    DOIs
    StatePublished - Dec 4 2015
    EventIngot Niobium Summary Workshop - Newport News, United States
    Duration: Dec 4 2015 → …

    Other

    OtherIngot Niobium Summary Workshop
    CountryUnited States
    CityNewport News
    Period12/4/15 → …

    Profile

    electromagnetic properties
    test stands
    ingots
    grain boundaries
    microstructure
    niobium
    purity
    penetration
    cavities
    crystals
    particle accelerators
    substructures
    microanalysis
    surface properties
    radio frequencies
    superconductivity
    electron diffraction
    transport properties
    breakdown
    vortices

    ASJC Scopus subject areas

    • Physics and Astronomy(all)

    Cite this

    Sung, Z. H., Lee, P. J., Polyanskii, A., Balachandran, S., Chetri, S., Larbalestier, D. C., ... Bieler, T. R. (2015). Large grain CBMM Nb ingot slices: An ideal test bed for exploring the microstructure-electromagnetic property relationships relevant to SRF. In Science and Technology of Ingot Niobium for Superconducting Radio Frequency Applications (Vol. 1687). [020004] American Institute of Physics Inc.. DOI: 10.1063/1.4935318

    Large grain CBMM Nb ingot slices : An ideal test bed for exploring the microstructure-electromagnetic property relationships relevant to SRF. / Sung, Zu Hawn; Lee, Peter J.; Polyanskii, Anatolii; Balachandran, Shreyas; Chetri, Santosh; Larbalestier, David C.; Wang, Mingmin; Compton, Christopher; Bieler, Thomas R.

    Science and Technology of Ingot Niobium for Superconducting Radio Frequency Applications. Vol. 1687 American Institute of Physics Inc., 2015. 020004.

    Research output: ResearchConference contribution

    Sung, ZH, Lee, PJ, Polyanskii, A, Balachandran, S, Chetri, S, Larbalestier, DC, Wang, M, Compton, C & Bieler, TR 2015, Large grain CBMM Nb ingot slices: An ideal test bed for exploring the microstructure-electromagnetic property relationships relevant to SRF. in Science and Technology of Ingot Niobium for Superconducting Radio Frequency Applications. vol. 1687, 020004, American Institute of Physics Inc., Ingot Niobium Summary Workshop, Newport News, United States, 12/4/15. DOI: 10.1063/1.4935318
    Sung ZH, Lee PJ, Polyanskii A, Balachandran S, Chetri S, Larbalestier DC et al. Large grain CBMM Nb ingot slices: An ideal test bed for exploring the microstructure-electromagnetic property relationships relevant to SRF. In Science and Technology of Ingot Niobium for Superconducting Radio Frequency Applications. Vol. 1687. American Institute of Physics Inc.2015. 020004. Available from, DOI: 10.1063/1.4935318
    Sung, Zu Hawn ; Lee, Peter J. ; Polyanskii, Anatolii ; Balachandran, Shreyas ; Chetri, Santosh ; Larbalestier, David C. ; Wang, Mingmin ; Compton, Christopher ; Bieler, Thomas R./ Large grain CBMM Nb ingot slices : An ideal test bed for exploring the microstructure-electromagnetic property relationships relevant to SRF. Science and Technology of Ingot Niobium for Superconducting Radio Frequency Applications. Vol. 1687 American Institute of Physics Inc., 2015.
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