Development of 10kA Bi2212 conductor for fusion application

Isono, Takaaki; Nunoya, Yoshihiko; Ando, Toshinari*; Okuno, Kiyoshi; Ono, Michitaka*; Ozaki, Akira*; Koizumi, Tsutomu*; Otani, Nozomu*; Hasegawa, Takayo*

Japan Atomic Energy Research Institute has started development work on a large current conductor using high Tc superconductor (HTS) aiming at a fusion power reactor after the International Thermonuclear Experimental Reactor (ITER). HTS has a capability to produce a magnetic field of higher than 16 T, which is required in such a fusion power reactor. A trial fabrication of a 10-kA 12-T conductor was started using round Ag-alloy sheathed Bi-2212 strands, which has best performance at 4.2K, 16T at present. The conductor has about 34-mm diameter, and is composed of 729 HTS strands. Operating temperature is designed at not only 4 K but also 20K. The conductor sample is indirectly cooled and is solder-coated on the surface to use specific heat of the lead as much as possible, which at 20 K is almost comparable with specific heat of SHe at 4.5K, 0.6MPa. From the tests of the conductor, the fabrication of large HTS conductor and 10kA operation at 12 T and about 12.5 K were successfully performed and the possibility of HTS to use fusion application was demonstrated.