EFDA-JET-PR(04)60
Structure, Stability and ELM Dynamics of the H-Mode Pedestal in DIII-D
Experiments are described that have increased understanding of the transport and stability physics that set the H-mode edge pedestal width and height, determine the onset of Type-I Edge Localized Modes (ELMs), and produce the nonlinear dynamics of the ELM perturbation in the pedestal and Scrape-Off Layer (SOL). Models now exist for the ne pedestal profile and the pe height at the onset of Type-I ELMs, and progress has been made toward models of the Te pedestal width and nonlinear ELM evolution. Similarity experiments between DIII-D and JET suggested that neutral penetration physics plays an important role in the relationship between the width and height of the-ne pedestal. Plasma physics appears to dominate in setting the Te pedestal width. Measured pedestal conditions including edge current at ELM onset agree with intermediate-n peeling-ballooning (P-B) stability predictions. Midplane ELM dynamics data show the predicted (P-B) structure at ELM onset, large rapid variations of the SOL parameters, and fast radial propagation in later phases, similar to features in nonlinear ELM simulations.