On the resistive transition of composite superconductors

Resistive transition of composite superconducting wires and cables that contain NbTi and Nb3Sn is investigated. Several aspects, as the change of resistivity as a result of an increase of one or more of the variables such as current, magnetic field, temperature and strain are demonstrated. In its essence, the resistive transition of the super-conducting material refers to an electro-magnetic phenomenon: motion of flux lines. These investigations have been mainly performed by means of measurements of voltage-current characteristics. The shape of these characteristics of technical superconductors is determined by a large variety of factors, because these wires consist of filamentary super-conducting material embedded in a normal conducting matrix material as copper, copper-nickel or bronze. As a result, the resistive transition of the composite is determined by the basic flux-motion behaviour and large aspects of matrix resistivity, geometry e.t.c. (author). 105 refs.; 74 figs.; 12 tabs