The superconducting transformer of the Samsung Superconductor Test Facility (SSTF)

In the frames of designing the SSTF (Samsung Superconductor Test Facility) for the KSTAR (Korea Superconducting Tokamak Advanced Research), the 50 kA transformer charging a CICC (cable-in-conduit conductor) short sample for o ne second is now under design. The primary winding conductor consists of si x NbTi and six stainless steel strands cabled around a low RRR rectangular copper core, which was used by Kurchatov Institute in small SMES (supercond ucting magnetic energy storage) windings. The secondary winding consists of 24 subcables wrapped around and soldered to a low RRR copper strip. Each s ubcable consists of six NbTi strands cabled around a copper strand. The str ands for primary and secondary windings are 0.85 mm diameter NbTi wires wit h six micrometer 8910 filaments. Both primary and secondary conductors have large current and temperature margins to ensure a reliable operation of th e superconducting transformer. The primary coil is placed in a cylindrical LHe vessel. The four secondary turns are glued to the outer surface of the LHe vessel The joints between the transformer and the sample are described.