Development of Nb3Sn tapes having low AC losses

A process has been developed for modifying the surface topography of Nb3Sn tapes produced by the diffusion process such that losses at 60 Hz and 4.2 K are reduced by a factor of 4 or more. The process comprises an etching sequence followed by reapplication of tin; the latter operation restores solderability for the subsequent fabrication of laminated conductor and, under some conditions, contributes to the reduction of ac losses. The treated superconductor tapes apparently fulfill the essential requirements established for superconducting ac power transmission cables.