ATTAINMENT OF HIGH FUSION REACTIVITY UNDER HIGH BOOTSTRAP CURRENT FRACTION IN JT-60U

The fusion performance of high beta(p) plasmas with significant D-D neutron production up to (5.6 +/- 0.6) x 10(16) n/s has been investigated. The attainment of a high fusion triple product, n(d)(0) tau(E)total T(i)(0), up to (1.1 +/- 0.3) x 10(21) m-3.s.keV is confirmed by both time dependent and time slice analysis. The highly enhanced confinement of up to 3.6 times ITER-89P scaling is dominated by the improved thermal confinement, and one half of the D-D neutrons come from the thermal reactions. The highest equivalent Q(DT) of approximately 0.56 was obtained. The ratio Q(DT)/Q(DD) is in the range 133-151. More importantly, a high bootstrap current of up to approximately 1 MA (approximately 50% of the total current) was obtained simultaneously with the high fusion performance. These results are quite encouraging as far as the realization of a steady state tokamak reactor is concerned.