Research and development of superconductors for commercial frequency

For the purpose of developing superconductors of low AC loss applicable to power apparatuses operating at commercial frequency, NbTi and Nb/sub 3/Sn were studied in the strand stage in the framework of the Japanese Super-GM. Basic data concerning processability, AC loss reduction, and current density enhancement were obtained. Excellent values of critical current density (30000 A/mm/sup 2/ at 0.5 T) and hysteresis loss (0.07 kJ/m/sup 3/ at +or-0.5 T) in superconductivity could be obtained for NbTi wires. As regards superconductivity for Nb/sub 3/Sn wires, critical current density could be enhanced by improving heat treatment, and AC loss could be reduced by addition of alloying elements and optimum arrangement of filaments.>