Progress and issues in understanding the physics of ELM dynamics, ELM mitigation, and ELM control

Oyama, Naoyuki

This paper reports progress and issues in physics understanding of dynamics, mitigation and control of ELMs, which have been recognized as one of the important issues in ITER. As for the ELM dynamics, studies of ELM precursor, filamentary structures during the collapse phase, dependence of ELM energy loss on the toroidal rotation and edge stability are progressed. In the small/no ELM regimes, expansion of the operational space toward low collisionality region has been achieved in type V ELM. In grassy ELM regime and QH-mode regime, ELM frequency dependence and EHO characteristics in term of edge rotation have been observed, respectively. As for the ELM control, the applicability of pellet pacing and external ELM control coils to ITER is discussed. Since the effect of toroidal rotation is now recognized as a fundamental parameter, the reliable prediction of edge rotation in ITER becomes more important.