Development of Advanced Operation Scenarios in Weak Magnetic-Shear Regime on JT-60U

Fully non-inductive discharge having relaxed current profile and high bootstrap current fraction fBS=0.5 has been realized in the highp ELMy H-mode discharge with weak magnetic-shear satisfying q95=5.8, qmin=2.1, and q(0)=2.4, where qmin and q(0) are the safety factor q at the minimum and the plasma center, respectively. The rest of the plasma current is externally driven by neutral beams (NBs) and lower-hybrid (LH) waves. The safety factor profile evaluated by the motional Stark effect (MSE) diagnostic is kept unchanged during 0.7 s at the end of the full current drive (CD) sustainment for 2 s (1.5 times the current relaxation time). The loop voltage profile is spatially uniform at 0 V at the end of the sustainment. This demonstration contributes to the ITER steady-state operation scenario development. Another ITER advanced operation scenario, the hybrid operation scenario, has also been developed in the highp ELMy H-mode with q95=3.2 and qmin~1. Period of sustainment at high N=2.6 has been almost tripled (to 28 s), and the JT-60U operation regime has extended toward longer sustainment and higher N. The development of advanced scenarios in JT-60U in these weak magnetic-shear regime leads development of advanced scenarios in ITER.