Progress in Steady-State High Performance and Related Technologies in the JT-60U Tokamak

Progress on NNB technology enables to demonstrate the N-NB driven current of around 1 MA with the efficiency of 0.155×10²⁰nT⁻²A/W. A newly installed 110GHz ECH system has demonstrated efficient central electron heating (T_e(0)>15keV) and local current profile control. Multiple pellet injection from high-field-top side into ELMy H-mode plasma has produced a high confinement plasma (HH_y2~1.05) at high density regime (n_e/n_GW~0.7). The both-leg divertor pumping has enhanced He exhaust by ~40%. Ar-puff experiments have improved confinement at high density with detached divertor due to high pedestal temperature. Based on these progresses in each issue, discharge optimization has been made to demonstrate integrated high performance plasmas. In the two advanced operation regimes (the reversed magnetic shear (RS) and the weak magnetic shear high-βp ELMy H-mode), discharges have been sustained near the steady-state current profile solution under full non-inductive current drive with proper driven current profiles (High βp; HH_y2~1.4 and β_N ~2.5 with N-NB, RS; HH_y2~2.2 and β_N ~2 with f_BS~80%).