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Title: Quantitative correlation between the void morphology of niobium-tin wires and their irreversible critical current degradation upon mechanical loading

Understanding the critical current performance variation of Nb 3Sn superconducting wires under mechanical loading is a crucial issue for the design of next generation accelerator and fusion magnets. In these applications, the mechanical properties of the conductors may become a limiting factor due to the strong electro-magnetic forces resulting from the combination of large magnets and intense magnetic fields. In particular, the presence of voids in the superconducting filament structure, which are formed during the fabrication and the reaction heat treatment, determines localized stress concentrations and possibly the formation of cracks. In this work, we demonstrate a quantitative correlation between the void morphology and the electro-mechanical limits measured on different Bronze route Nb 3Sn wires. Hot Isostatic Pressing (HIP) prior to the reaction heat treatment is utilized to partially eliminate the voids. The wires’ void distributions - with and without HIP treatment - are detected and statistically analyzed using high energy X-ray micro tomography. The stress concentration due to the shape and distribution of the voids as well as their impact on the electro-mechanical properties are determined through finite element method modeling. Lastly, the results are quantitatively correlated with the experimentally determined limits of the irreversible critical current degradation uponmore » mechanical loading.« less
Authors:
ORCiD logo [1] ;  [1] ; ORCiD logo [2] ;  [1] ;  [3] ;  [1] ; ORCiD logo [1]
  1. Univ. of Geneva, Geneva (Switzerland)
  2. European Synchrotron Radiation Facility (ESRF), Grenoble (France)
  3. Princeton Univ., Princeton, NJ (United States). Princeton Plasma Physics Lab. (PPPL)
Publication Date:
Type:
Accepted Manuscript
Journal Name:
Scientific Reports
Additional Journal Information:
Journal Volume: 8; Journal Issue: 1; Journal ID: ISSN 2045-2322
Publisher:
Nature Publishing Group
Research Org:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; Characterization and analytical techniques; Superconducting properties and materials
OSTI Identifier:
1436733