CONFINEMENT AND DIVERTOR STUDIES IN JAPAN TOKAMAK JT-60U

This paper presents confinement characteristics of H mode and high beta(P) mode in Japan Tokamak JT-60U [Plasma Devices Operat. 1, 43 (1990)], effects of current profiles, pressure profiles and sawtooth oscillations on the operational limits and energy confinement, and divertor characteristics. The operational regime required for core plasma performance and divertor conditions is discussed on the basis of the experimental results. The main parameters achieved in confinement studies are T(i)(0) = 38 keV, n(d)(0)T(i)(0)tau(E)global approximately 4.4 X 10(20) m-3 sec keV, H factor {defined by tau(E)/tau(E)ITER89P L mode [Nucl. Fusion 30, 1999 (1990)]} approximately 3 at epsilonbeta(P) approximately 0.5 in high beta(P) mode and n(d)(0)T(i)(0)tau(E)global approximately 2.5 X 20(20) m-3 sec keV in H-mode discharges with B(T) = 4.2 T. Advantages ot' high q operation are suggested from studies on operational regime and confinement. The divertor study shows that a parameter n(e)BAR q(eff) (q(eff): effective safety factor) plays a role in characterizing divertor actions such as relaxing of heat flux profiles, radiation loss and deuterium recycling. High n(e)BAR q(eff) operation is shown to be essential for the alleviation of heat load on the divertor.