Development of a forced-cooled superconducting coil with high average current density (DPC-TJ)

A forced-cooled superconducting coil (DPC-TJ) using a double-walled cable-in-conduit, the so-called Performed Armor CICC, has been developed. The DPC-TJ is an advanced coil with an average current density of 40 A/mm/sup 2/, operating current of 24 kA, and field of 12 T. The DPC-TJ coil has several advantages such as mechanical rigidity, negligible degradation of critical current, sound electrical insulation, and excellent winding tolerance compared with a conventional forced-cooled coil. A superconducting strand was developed with the aim of improving the critical current density and resistivity. The resulting Nb-tube-processed (NbTi)/sub 3/Sn strand fulfils the requirement that the critical current density be more than 600 A/mm/sup 2/ at 12 T and the RRR (residual resistivity ratio) be higher than 50.<
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