26th IAEA Fusion Energy Conference - IAEA CN-234

Study of toroidal rotation and ion temperature pedestals between ELM bursts on KSTAR H-mode plasmas

19 Oct 2016, 14:00

4h 45m

Kyoto International Conference Center

Poster EXW - Magnetic Confinement Experiments: Wave–plasma interactions; current drive; heating; energetic particles Poster 4

Speaker

Dr Sehoon Ko (National Fusion Research Institute)

Description

Steep pedestal profiles of ion temperature (Ti) and toroidal rotation (VФ) are routinely observed in neutral beam injection(NBI)-heated KSTAR H-mode plasmas[W. H. Ko et al Nucl. Fusion {\bf55} 083013 (2015)]. In this work, we report a result of detailed analysis of pedestal characteristics. By analyzing a set of data with different experimental conditions, we show that Ti and VФ pedestals are coupled each other whose correlation becomes stronger when NBI-power is low. This suggests the existence of intrinsic toroidal torque in the pedestal. To investigate further the magnitude and the role of intrinsic torque, we perform a 1D transport analysis and find that the prevalence of residual micro-turbulences is necessary to explain momentum transport in the pedestal. The estimated strength of intrinsic torque is shown to be comparable to that from a 2.7MW NBI source. Finally, we show that non-diffusive momentum flux is indispensable to explain momentum transport in the pedestal and a residual stress model fits the observed momentum flux reasonably.