Critical current degradation of a NbTi-multifilament conductor due to heat treatment

• Published in: IEEE Transactions on Magnetics (Institute of Electrical and Electronics Engineers); (United States) Vol. 30; no. 4; pp. 2391 - 2394
• Main Authors: Schneider, T., Turowski, P.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: New York, NY IEEE 01.07.1994; Institute of Electrical and Electronics Engineers
• Subjects: 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ALLOYS; Annealing; Applied sciences; CABLES; CLOSED PLASMA DEVICES; CONDUCTOR DEVICES; Conductors; CRITICAL CURRENT; Current measurement; CURRENTS; DATA; ELECTRIC CABLES; Electric connection. Cables. Wiring; ELECTRIC CURRENTS; Electrical engineering. Electrical power engineering; ELECTRICAL EQUIPMENT; ELECTROMAGNETS; Exact sciences and technology; EXPERIMENTAL DATA; FABRICATION; INFORMATION; MAGNETS; NIOBIUM ALLOYS; NUMERICAL DATA; Production; Soldering; STELLARATORS; SUPERCONDUCTING CABLES; Superconducting coils; SUPERCONDUCTING DEVICES; SUPERCONDUCTING MAGNETS; SUPERCONDUCTING WIRES; Thermal degradation; THERMONUCLEAR DEVICES; TITANIUM ALLOYS; Various equipment and components; Welding; WENDELSTEIN-7 STELLARATOR; WIRES 700430 > Fusion Technology > Magnet Coils & Fields > (1992-); Electrical engineering; Titanium alloy; Heat treatment; Electrical properties; Niobium alloy; Heat flow; Experimental study; Stellarator; Superconducting wires; Multifilamentary superconductor; Degradation; Winding; Critical current; Superconductive winding; Superconducting cable; Electrical conductor; Binary alloy
• ISSN: 0018-9464; 1941-0069
• DOI: 10.1109/20.305758

In the framework of the development of superconducting coils for the stellarator Wendelstein 7-X, the reduction of the critical current due to thermal treatment was investigated. During production steps like the extrusion of the Al-jacket onto the superconducting cable and also during welding and soldering, heat flux into the NbTi-strands occurs. For optimized NbTi-strands a degradation of the critical current was expected. The results of measurements of the critical current of an annealed NbTi multifilamentary superconductor at 4.2 K in the field range from 2 T to 10 T are presented. The commercially available conductor has been annealed at various temperatures up to 600/spl deg/C and times up to 120 s in order to simulate the conditions during such production steps. Special attention is paid to the shape of the voltage-current transition which is characterized on the one hand by a power law and on the other hand by an exponential function.< >