Magnetization of in situ multifilamentary superconducting Nb3Sn-Cu composites

Magnetic properties are reported for in situ superconducting Nb
3
Sn composites that have exhibited attractive electrical properties and superior mechanical characteristics. Magnetization measurements were conducted up to 4 T at 4.2 K on a variety of samples of different sizes and twist pitches, and the results are presented in absolute M-H curves and losses per cycle. It is observed that the magnetization of such composites is generally proportional to the size of the wire (∼0.25 to 0.51 mm) rather than the fiber size (
\sim10^{-7}
m), which indicates a strong coupling effect among Nb
3
Sn fibers.