Study on electrophysical properties off Nb3Sn-based tape superconductors

The results of measurements of electrophysi al properties of Nb3Sn-based standard superconductors (SC) are presented. Volt-ampere and volt-temperature characteristics (VAC and VTC) of tape SC of 5 mm width with a superconducting layer of 5 μm thickness and 25 μm copper substrate thickness are presented. The specific features of both characteristics is their ''lengthiness''. This circumstance requires application of a two-coordinate technique of VAC and VTC measurement and introduction of their functional description. VAC description by ''crytical current'' i. e. by a single point is unsatisfactory. The investigated SC anisotropy parameter K=Isub(c parallel)/Isub(c perpendicular) < 1, which makes VAC of the Nb3Sn tape SC in a perpendicular to a wide tape side magnetic field strongly ''lengthy''. Local reduction of the current-carrying capability of some samples, existence of VAC jumps, appearance of VAC jumps at sample tension are due to ''narrow'' defect areas which can be found by means of a continuous control of SC magnetization. The two-dimensional character of current overflow on the SC layer+normal metal is also a reflection of SC property heterogeneity over its length and width. The performed investigations of electrophysical properties of Nb3Sn tape SC as well as study on design of superconducting magnetic systems from these SC prove the necessity in control of uniformity of current carrying capability of tape SC over their length