G. Kurita, K. Ushigusa, M. Kikuchi, K. Nagashima, Y. Neyatani, N. Miya, N. Toyoshima, Y. Takahashi, T. Hayashi, M. Kuriyama, T. Yamamoto, K. Tobita, H. Kubo, N. Hosogane, A. Nagashima, K. Masaki, A. Kaminaga, K. Nakagawa, K. Mori, T. Kitai, S. Oguri, M. Otsuka1), K. Nakashima2), S. Nakagawa3), T. Suzuki4), M. Nagami, H. Kishimoto
Japan Atomic Energy Research Institute, Naka Fusion Research Establishment
Naka-machi, Naka-gun, Ibaraki-ken, 311-01 Japan
1) Hitachi limited, 2) Mitsubishi F.C., 3) Toshiba corp., 4) Kawasaki heavy industries.
To realize the steady-state tokamak reactor SSTR, simultaneous achievement is required at high q (5-6) and high bp (2-2.5), in addition to the alpha burning, of (1) high energy confinement (H-factor>2) under good particle controllability, (2) stable high normalized beta (bN ~3.5), (3) high bootstrap current fraction and high efficiency non-inductive current drive, and (4) heat load reduction and He ash exhaust with divertor. The JT-60SU machine has been studied to establish such a reactor relevant operation mode using deuterium as well as to contribute to the advanced ITER scenario.
The cryostat diameter and height of JT-60SU are 22m and 17.5m, respectively. The total weight of the device including cryostat is ~11000ton. Toroidal field magnet consists of 18 coils to produce 6.25T at 4.8m. Various plasma shape can be produced by ten blocks of poloidal field coils to explore optimum plasma shape in a tokamak.(elongation kx up to 2.0 and triangularitydx up to 0.8 for double null configuration). The maximum plasma current of 10MA is chosen to study reactor relevant plasma. The current drive system with total injection power of 60MW is a combination of N-NBI and ECH to allow a wide range of current profile control. Demonstration of 5MA full current drive is planned for 1000s-1Hr at ne~8.8x1019m-3 which is around the Greenwald density limit. Normalized beta bNfor 5MA full CD operation is ~2.0, which is stable with the edge bootstrap current, expected for H-mode edge transport barrier, of Jedge/Jo~0.3 without conducting shell. The vacuum vessel is made of low cobalt concentration (0.05%) 316SS and the extra shield made of RAF(reduced activation ferritic steel) will be installed for the possible DT option. One turn resistance of the vacuum vessel is 25mW to allow plasma initiation with EF 0.2V/m. The growth rate of the vertical instability g and stability margin ms=(ns(infinity)+n)//n/ are g 30/s and ms 0.5, respectively, with toroidally continuous divertor baffle plate. Main fraction of the neutron and g-rays are shielded by the vacuum vessel, TF shear-panel and the cryostat.