Coils performances of superconducting cables for 50/60 Hz applications

Multifilamentary superconducting wires with a greatly reduced level of losses have been produced with unit lengths of several tens of kilometers. With the reduction of the filament diameter, proximity effects are avoided and maximum advantage is taken of the reversible motion of flux lines, so that the hysteretic and matrix losses are lower. These concepts have led to the manufacture on an industrial scale of three wires comprising 377982, 597102 and 920304 filaments of NbTi with a diameter of 0.14 μm and a 0.13-μm spacing between the filaments. The matrix material is 30%-Ni-content copper-nickel. Cables made from six such insulated wires have been made with more than 1-km kilometer unit lengths. Numerous impregnated and nonimpregnated coils have been wound with single strands and 6+1 cables. A report is presented on 50-Hz and DC quench currents, 50-Hz AC losses, and 50-Hz electromagnetic stability results. These results are analyzed taking into account proximity effects, reversible motion of flux lines, current sharing, and the thermal behavior of the coil