MAGNETIZATION AND CRITICAL CURRENT-DENSITY OF ULTRA-FINE MULTIFILAMENTARY SUPERCONDUCTING WIRES

Multifilamentary superconducting wires with a greatly reduced level of losses have been produced with lengths of several tens of kilometers. In spite of the reduction of the filament diameter, proximity effects are avoided, and we make the best possible use of the reversible motion of the flux lines, so that the hysteretic losses are reduced. The concepts lead us to realize conductors comprising filaments of Nb-Ti, with a 0.1 to 0.2-mu-m diameter embedded in a highly resistive CuNi matrix. In order to characterise the possible applications to industrial power systems, we should investigate in a quite precise way, the losses in submicronic filaments. We can determine the correct value of the critical current density with critical current measurements and magnetization curves on such wires.