Design and Fabrication of Forced-Flow Coils as R&D Program for Large Helical Device

摘要

As research and development of helical field coil and poloidal field coil for Large Helical Device (LHD), two forced-flow cooled NbTi superconducting coils (TOKI-TF, PF) have been designed and fabricated. The helical coil (TOKI-TF) is a 1/4 scale model of LHD. It has the major radius of 0.9 m, the minor radius of 0.25 m and pitch number of 4. Nominal current and maximum field were designed to be 8 kA and 2.8 T, respectively. Another coil (TOKI-PF) was fabricated for the demonstration of LHD poloidal field coils. It consists of two double-pancakes with the inner radius of 0.6 m and the outer radius of 0.82 m. Nominal current of 25 kA simulates that of LHD poloidal field coils. Cable-in-conduit type conductors were used for the both coils. The test facility was also constructed with a vacuum vessel, Iiquid nitrogen shield, 30 kA power leads, a heat exchanger, cryogenic supports and others. In this paper, design concepts and details will be presented.