Process for scalable fabrication of low AC loss HTS conductors

Abstract

A scalable process has been developed to fabricate low AC loss cable from second generation high-temperature superconducting (2G HTS) coated conductors with an emulated Rutherford twisted conductor topology. The process uses an indexed tape design to precisely align separate YBCO tapes to form a single tape structure making it compatible with a reel-to-reel production process and involves a combination of three methods: (1) the use of laser lithography to striate 2G HTS tapes into a pattern of isolated diagonal filaments, (2) the precise alignment and decal bonding of a pattern of solder preforms to the filament edge contact areas, and (3) the alignment and bonding of a top and bottom HTS tape with a thin intervening adhesive layer that provides mechanical adhesion and electrical isolation between adjacent bonds and the interior where filament transposition occurs. The observation of a resistive critical current transition in the fully fabricated transposed striated HTS conductor indicates that all bonds were well formed and the superconducting current path was restricted to the filaments.