Development of Nb-Ti cable with ultra-fine filament and high resistivity matrix for ac use

Abstract

The superconducting ac machines such as transformer and reactor are greatly expected to have an important role in the future electric power transport lines. In these machines, superconducting coils are wound by superconducting cables which have low ac loss, stable ac quenching current and high normal resistivity. We have developed Nb-Ti superconducting cables with ultra-fine filament and high resistivity matrix to apply these coils. A cable developed has a structure of double stranded round type using 0.2mm φ strand with 0.14 μm filament and Cu-30wt%Ni as a matrix material. 50Hz quenching current without external magnetic field exceeds 1400Arms. AC loss is 15kW/m3 at the transverse external magnetic field of 0.5T, 50Hz, and normal resistivity is 0.21Ω/m at 0T, 10K.