Fine Filament NbTi Conductors: Design and Large Scale Production

Abstract

According to the present specifications, the accelerators and storage rings of the next generations like LHC, SSC, UNK, RHIC and ELOISATRON will require beam line magnets wound from keystoned cables consisting of strands with fine filaments. The specified filament diameters are between 6 µm down to about 2.5 µm in order to reduce field distortions due to persistent currents inside the filaments. In addition, the filament spacing must be large enough to avoid coupling between the filaments. The required distance depends on the matrix material and a safe choice is of the order of 1 µm for pure Cu. It can be made much smaller for Cu-alloys like CuNi and CuMn (in case of NbTi) or CuSn (for Nb₃Sn).