Multifilamentary Nb3Sn composite conductors: Final report to Lawrence Livermore Laboratory

The development of manufacturing techniques for a multifilamentary Nb3Sn composite conductor of unique design is described. The uniqueness of the design lies in the use of hollow niobium filaments in a high conductivity copper matrix. Each filament contains a core of bronze. During heat treatment the tin migrates from the bronze to the inner wall of the niobium filament where the Nb3Sn is formed. The outer unreacted part of the niobium filament serves as a barrier to protect the purity and high conductivity of the copper. Thus, each filament is stabilized in the same way as in the composite NbTi conductors. Test samples of conductor containing large numbers of filaments were made from small two inch diameter billets.