Advantages of Cu-Nb Reinforced Nb }Sn Strands in Large Multi-Stage Stranded Cables With Low-Void Fraction

• Published in: IEEE transactions on applied superconductivity Vol. 34; no. 5; pp. 1 - 6
• Main Authors: Sugimoto, Masahiro, Hirose, Kiyoshige, Taniguchi, Ryo, Ebisawa, Koichi, Awaji, Satoshi, Oguro, Hidetoshi, Utoh, Hiroyasu, Sakamoto, Yoshiteru
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-08-2024; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Bending; Cables; Conductors; Copper; Force; Low-void fraction; Manufacturability; Mechanical properties; multi-stage stranded cable; Nb-rod-method Cu-Nb; 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; Niobium; Nuclear power plants; Prototypes; reinforcement; Strands; Stress; Superconducting cables; Tin; Void fraction; Wires
• ISSN: 1051-8223; 1558-2515
• DOI: 10.1109/TASC.2024.3374255

A large multi-stage stranded cable structure with Nb<inline-formula><tex-math notation="LaTeX">_{\text{3}}</tex-math></inline-formula>Sn strands twisted at a short-pitch and compressed to a low-void fraction is a major candidate for Nb<inline-formula><tex-math notation="LaTeX">_{\text{3}}</tex-math></inline-formula>Sn conductors for JA-DEMO-TF coils. To realize the conductor, we have proposed the application of Nb-rod-method Cu-Nb reinforced ITER-CS type Nb<inline-formula><tex-math notation="LaTeX">_{\text{3}}</tex-math></inline-formula>Sn strands (Cu-Nb/Nb<inline-formula><tex-math notation="LaTeX">_{\text{3}}</tex-math></inline-formula>Sn wires). Prototype 4th-stage stranded cables simulated the stranded process for the ITER-CS conductor and for the JA-DEMO-TF conductor were fabricated using the Cu-Nb/Nb<inline-formula><tex-math notation="LaTeX">_{\text{3}}</tex-math></inline-formula>Sn strands or conventional non-reinforced ITER-CS strands (Cu/Nb<inline-formula><tex-math notation="LaTeX">_{\text{3}}</tex-math></inline-formula>Sn wires), and compression-formed to a low-void fraction below 30%. Cu-Nb/Nb<inline-formula><tex-math notation="LaTeX">_{\text{3}}</tex-math></inline-formula>Sn strands extracted from the compacted 4th-stage cables had no degradation of I c as well as Cu/Nb<inline-formula><tex-math notation="LaTeX">_{\text{3}}</tex-math></inline-formula>Sn strands. Destructive investigation of the compacted 4th-stage cables showed Cu-Nb/Nb<inline-formula><tex-math notation="LaTeX">_{\text{3}}</tex-math></inline-formula>Sn cables had better manufacturability of the large multi-stage stranded cables with low-void fraction than the conventional Cu/Nb<inline-formula><tex-math notation="LaTeX">_{\text{3}}</tex-math></inline-formula>Sn cables. Moreover, the Cu-Nb/Nb<inline-formula><tex-math notation="LaTeX">_{\text{3}}</tex-math></inline-formula>Sn triplex had improved current-carrying properties under transverse compression stresses by enhancement of the mechanical properties. In this study, the advantages of applying Cu-Nb/Nb<inline-formula><tex-math notation="LaTeX">_{\text{3}}</tex-math></inline-formula>Sn strands for the large multi-stage stranded cables with low-void fraction are discussed.