Speaker: Dr. Ahmed Diallo, Princeton Plasma Physics Laboatory
Abstract: Fusion performance of the International Thermonuclear Experiment Reactor (ITER) is predicted to be proportional to the square of the pedestal pressure height. The reference scenario for the ITER high confinement mode is projected to be in the Type I edge localized mode (ELMy) regime where the maximum pedestal (edge) pressure is reached leading to an enahcement of the fusion gain. It is also well known that ELMs pose a threat to the plasma facing components. Controlling ELMs is necessary and hence it is vital to understand the underlying physics. In recent years, substantial progress has been made in pedestal research on the National Spherical Torus Experiment (NSTX). Characterizations of the pedestal parameter dynamics and microturbulence in the pedestal region throughout the edge localized modes (ELM) cycles are performed. More specifically, this talk will be describing the current understanding of the inter-ELM evolution, approach to instability of the edge pedestal, and summarize ongoing work aimed at identifying the microturbulence limiting the pedestal gradient. Finally, transition to ELM-free operations enabled by lithiumcoated walls will be discussed as such regime provides larger pedestal pressure than in ELMy cases.