Superconductor development and future trends

There is general agreement that progress in increasing J/sub c/ has been rapid and will continue. Flux pinning theory has not been a good guide because of the very complex metallurgy of NbTi as processed. Even though precipitate sizes are now much smaller than coherence lengths, improvements are still being made. The only large-scale production history for Nb3Sn has been with bronze matrix material which has a predictable J/sub c/ of 650-850 A/mm (10 T, 4.2 K). (This is probably not high enough to be economically attractive for most accelerator applications.) Fabrication processes for NbTi and Nb3Sn are discussed