Overview of JT-60U Results toward High Integrated Performance in Reactor-Relevant Regime
T. Fujita, JT-60Team
Japan Atomic Energy Research Institute, Naka Fusion Research Establishment Naka-machi, Naka-gun, Ibaraki-ken, Japan.
Abstract.
Recent JT-60U results toward high integrated performance are reported with emphasis on the projection to the reactor-relevant regime. N-NB and EC power increased up to 6.2 MW and 3 MW, respectively. A high βp H-mode plasma with full non-inductive current drive has been obtained at 1.8 MA and the fusion triple product reached 3.1x1020 m-3keVs. High beta with 
=2.7 was maintained for 7.4 s. NTM suppression with EC was accomplished using a real-time feedback control system and improvement in was obtained. A stable existence of current hole was observed. High DT-equivalent fusion gain of 0.8 was maintained for 0.55 s in a plasma with a current hole. The current profile control in high bootstrap current reversed shear plasmas was demonstrated using N-NB and LH. A new operation scenario has been established in which a plasma with high bootstrap current fraction and ITBs is produced without the use of OH coil. ECCD study was undertaken in a reactor-relevant high Te regime. A new type of AE mode has been proposed and found to explain the observed frequency chirp quite well. High confinement reversed shear plasmas with Te>Ti were obtained. Ar exhaust with EC heating was obtained in a high βp mode plasma. Impurity accumulation related to strong ITBs in a reversed shear plasma and degradation of ITB by ECH in a weak positive shear plasma have been found. Dedicated measurement of ELM dynamics and SOL plasma flow advanced the physics understanding. N-NB heating in an Ar-seed plasma extended the density region to 95% of Greenwald density with HHy2=0.9. The enhancement of pedestal pressure was obtained with an increase of βp in a high triangularity configuration.