Investigation into the strain tolerance of BSCCO composite tapes

Intense research activity carried out worldwide has led to the development of high Tc superconducting tapes with electrical performances closer and closer to those required for power cables applications. In this perspective, the mechanical behavior of these tapes, which is known to be intrinsically rather poor, can turn out to be a critical factor. Mono and multifilamentary composite (silver sheathed) BSCCO tapes have been tested using a specially designed apparatus. The dependence of critical current on stress and strain has been investigated for different configurations, and possible models have been considered taking into account the structural parameters as well as the thermal history of the composite tapes. In particular, the effect of the pre-compression which is assumed to be imposed to the superconductor by the silver sheath during cool down has been analyzed. The comparison between experimentally determined maximum tolerable stress and strain of present tapes, and values typically required during cable manufacturing, handling and service conditions, is discussed. Possible ways to improve the strain tolerance of superconducting tapes are analyzed