Conductor fabrication for the HT-7U model coil

Hefei Tokamak HT-7 Upgrade (HT-7U) is a nuclear fusion experimental device with advanced tokamak operating modes. All of the coils will use NbTi/Cu Cable-in-Conduit Conductor (CICC) cooled with forced-flow supercritical helium (SHe). Up to date, the conductor fabrication for the central solenoid (CS) model coil has been completed. The length of the conductor is 370 m. The CICC consists of cabled 108 NbTi strands and 54 Cu strands in 316 L jacket by TIG welding. The outer dimensions of the conduit are 17.4 mm x 17.4 mm with an outer-corner radius of 3.5 mm. The void fraction of the conductor is 38 %. In this paper, we present a detailed description of the conductor manufacture for the CS model coil. (author)