26th IAEA Fusion Energy Conference - IAEA CN-234

Excitation of zonal flows and their impact on dynamics of edge pedestal collapse

21 Oct 2016, 08:30

4h

Kyoto International Conference Center

Poster THS - Magnetic Confinement Theory and Modelling: Stability Poster EX/9, EX/10, TH/7, TH/8, IFE/1, MPT/1, FNS/1

Speaker

Dr Hogun Jhang (National Fusion Research Institute)

Description

We study the role of zonal flows in edge pedestal collapse using a reduced magnetohydrodynamic (MHD) model. A dramatic change of dynamics happens when ideal ballooning modes are stabilized. A detailed analysis shows that a zonal flow driven instability is developed due to a strong excitation of zonal vorticity, resulting in secondary crashes. The presence of subsidiary bursts after a main crash increases the effective crash time and energy loss. These simulation results resemble the behavior of compound edge localized modes (ELMs). Thus, our results indicate that a complete understanding of ELM crash dynamics requires the self-consistent inclusion of nonlinear zonal flows-MHD interaction and transport physics.