Development of Ka-Class Superconducting Cables for AC Use (I)-Design and Fabrication

Abstract

A large current AC superconductors were fabricated and tested. A strand with more than 20000 NbTi filaments was extruded down to 0.153 mm in diameter to produce filaments of 0.57 µm in diameter. The mixed matrix composed of Cu and CuNi was employed. A final conductor was made of 12 2nd-level sub-cables (6×7 strands) with a mandrel and was compressed on its four sides like a Rutherford type one. Four kinds of conductor were fabricated; one had an FRP mandrel, and the other three had a stainless steel mandrel with various compression rate. They were wound on FRP bobbins to form coils. Three of four coils were successfully operated up to about DC 5 kA.