Speaker
Description
See the full abstract here http://ocs.ciemat.es/EPS2019ABS/pdf/O4.107.pdf
A 100 sec long-pulse steady-state H-mode plasma with good energy confinement (H98(y,2) ~ 1.1) has been successfully achieved on EAST using RF heating and current drive. Recent EAST experiments with improved hardware capabilities have demonstrated steady-state fully non-inductive scenarios with extension of fusion performance (Betap~2.5 & N~2.0, H98(y,2) ~ 1.2, <ne>/nGW~0.8, fBS~50% at q95~6.8) through integrated control of the wall conditioning and recycling, plasma configuration, divertor heat flux, particle and impurity control, and the effective coupling of multiple RF heating and current drive (H&CD) sources. This steady-state scenario was characterized with fully non-inductive current drive at high density with low rotation and high-frequency, small-amplitude edge localized modes (ELMs), and stable control of heat and particle exhaust using various technologies (e.g. RMP) on the ITER-like tungsten divertor. The optimization of the X-point, plasma shape, the outer gap and local gas puffing near the lower hybrid wave (LHW) antenna were integrated with global parameters of BT, line averaged electron density <ne> for high LHW current drive efficiency, and on-axis deposition of ECH in the long pulse operation. The benefits of using ECRH to avoid tungsten accumulation in the core plasma, and enhancement of H&CD by the synergistic effect of ECH and LHW were demonstrated. A higher energy confinement is observed at higher performance with favourable toroidal field direction. In addition, reduction of the peak divertor heat flux was successfully demonstrated using active radiation feedback control. Towards the next goal (400s long pulse H-mode operations with ~50% bootstrap current fraction) on EAST, an integrated control of the current density profile, the pressure profile and the radiative divertor will be addressed in the near future.
