Strain effects in cabled and braided "in situ" formed Nb3Sn conductors

Three-strand cables (pitch=15 and 30 mm) and three-strand braid (pitch=30 mm) have been made using "in situ" formed Nb3Sn wire (0.31 mm outer diameter) as strands, and their mechanical properties and strain effects have been investigated. The stress-strain relations of all the cables and braid examined are similar to that of the strand except in lower strain region. The degradations in the critical currents are observed for the cable with smaller pitch and the braid. Strain sensitivity of critical current is enhanced by braiding. The optimization of the pitch is required for cables and braids in order to fully utilize high critical current and high strain tolerence of "in situ" formed strands.