Review of JT-60 experimental results from June to October, 1987

This is a prompt report on JT-60 experimental results from June to October, 1987. Experiments in hydrogen plasmas have been undertaken with up to 3.2 MA of plasma current in limiter discharges, 2.7 MA in divertor discharges, and 30 MW of total NB (H0 → H+) and RF injection power. In limiter discharges with ∼3 MA plasma current, the maximum central electron density of 1.3 x 1020 m-3 and the energy confinement time of 0.15 - 0.18 sec were obtained with heating powers of 13 - 20 MW. The total plasma stored energy of 3.1 MJ, and ne(0)τE of 1.4 - 1.8 x 1019 m-3 sec were achieved. The best set of parameters achieved is ne(0)τE = 1.8 x 1019 m-3 sec and Ti(0) = 3.7 KeV at plasma current of 3.2 MA. By applying deutrium discharge condition, ne(0)τE and Ti(0) enter the JT-60 target area determined by Atomic Energy Commission. Many short periods (50 - 100 ms) of H-mode phase are found in outside X-point divertor discharges with NB or NB + RF (LH or IC) heating power of more than 16 MW, although at present the energy confinement improvement is limited to within 10 %. In combined LH and NB heating of low-n-bare discharge, the plasma stored energy increases with the same rate as NB heating only, with preferential absorption of LH wave to the high energy beam ions. In combined NB and on-axis ICRF heating of low-n-bare discharge, a high incremental energy confinement time is obtained, with strong high energy beam ion acceleration and electron heating in the central region of the plasma. (author)