Composite Superconducting MgB2 Wires Made by Continuous Process

Abstract

Previously developed manufacturing technology of a low-cost composite single core based MgB 2 superconductive wires has been investigated in details using monel sheath and titanium diffusion barrier. In this process, Mg and B as well as nanoSiC dopant powders were fed continuously to a “U”-shaped metallic sheath titanium, and subsequently monel sheath. Resulting wires were assembled in a “6 + 1” configuration cable constructed from six 0.75-mm Monel/Titanium/(MgB 2 + 10 wt%SiC) and Monel/Titanium/MgB 2 wires and one central copper wire with two twist pitch arrangements: 13 mm. Undoped and SiC-doped wires were compared in respect of their I c (B, T ) characteristic. Wires were sintered at 700 °C for different times and subsequently were initially tested in a dedicated helium force vapor cooling system at temperatures 20-35 K at 1 T. Systematic and statistic I c (B, T ) measurements of the wires and cables in LHe were conducted at high external magnetic flux density up to 9 T. It was shown that wire feeding, sealing, reduction, and forming technology enable virtually unlimited conductor lengths as well as in-line processing control simultaneously ensuring a high degree of reproducibility and consistent quality of the MgB 2 superconductor. Such generic single core MgB 2 conductors enable manufacture of multifilamentary MgB 2 conductors with desired configurations (e.g., twist pitch for transient losses and ac applications).