Evaluation of Bending Strain in Nb3Sn Strands of CIC Conductor Using Neutron Diffraction

• Published in: IEEE transactions on applied superconductivity Vol. 27; no. 4; pp. 1 - 5
• Main Authors: Hemmi, Tsutomu, Harjo, Stefanus, Kajitani, Hideki, Suwa, Tomone, Saito, Toru, Aizawa, Kazuya, Osamura, Kozo, Koizumi, Norikiyo
• Format: Journal Article
• Language: English
• Published: IEEE 01-06-2017
• Subjects: Bending strain; cable-in-conduit conductor (CICC); Conductors; Diffraction; ITER; Lattices; Nb<named-content xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:ali="http://www.niso.org/schemas/ali/1.0/" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" content-type="math" xlink:type="simple"> <inline-formula> <tex-math notation="LaTeX"> _3</tex-math> </inline-formula> </named-content>Sn; neutron diffraction; Neutrons; Niobium-tin; Strain; Strain measurement
• ISSN: 1051-8223; 1558-2515
• DOI: 10.1109/TASC.2017.2660064

The superconducting property of Nb 3 Sn strands is very sensitive to strain. The transverse electromagnetic loading has been considered as a major origin of the degradation of Nb 3 Sn cable-in-conduit conductors (CICCs) due to the local bending. Since the bending pitch is around 5 mm due to contacting of strands compacted by the electromagnetic transverse loading, there is a possibility of a large bending strain with small deflection of strands. The bending strain of the strands cannot be evaluated from only the small deflection obtained visually. Measuring bending strain of Nb 3 Sn strand in CICCs is important for evaluating the conductor performance. Neutrons, which have a large penetration depth, are a powerful tool to evaluate the internal strain of Nb 3 Sn in the CICC. This paper shows that the bending strain in Nb 3 Sn strands of CICCs can be determined by the neutron diffraction profile nondestructively and quantitatively.