PECULIARITIES IN ELECTROMAGNETIC BEHAVIOR OF MF NBTI COMPOSITES FOR AC USE

The paper presents results obtained in the study of the current - voltage characteristics, critical and quenching currents as well as of the AC transport current and magnetization losses in four series of fine filament NbTi composites prepared by Showa Electric Wire & Cable Co., Japan. Complementary measurements have been made also on a commercially available type T AC superconducting wire produced by GEC Alsthom Company, France. The samples differ in filament diameter, matrix thickness between filaments and in the number and structure of filament bundles in the composite. In two series of samples barrier type artificial pinning centers have been introduced to increase J(c) and decrease the normalized magnetization losses. The conclusions concerning the optimization of multifilamentary composites and cables for AC use at low working magnetic field are briefly reviewed.