Experiment and simulation of ELM in NBI heated plasma on EAST tokamak

By scanning toroidal rotation with a combination of co- and counter-current direction neutral beam injection (NBI) on the Experimental Advanced Superconducting Tokamak, it is found the size of edge localized mode (ELM) decreases with increasing toroidal rotation in counter-current direction. The synergistic effect of plasma rotation and collisionality on ELM behavior is also studied by statistical analysis. Three-field module in BOUT++ framework is employed to study the impacts of toroidal rotation/E x B flow shear on ELM behaviors. The BOUT++ simulation results show that both Co- and Ctr-NBI induced net flow have stabilization effects on the peeling-ballooning modes, especially for counter NBI case, high-n ballooning mode can be totally stabilized. With larger E x B shear, the mode number of most unstable mode downshifts in the counter NBI case, with larger E x B shear, the mode number of most downshifts in the counter NBI case, correlated with reduced ELM size.

Automated summary

Through experiments, it was found that counter-current toroidal rotation can reduce the size of edge localized modes (ELMs), while the net flow induced by both co- and counter-current neutral beam injection has a stabilizing effect on peeling-ballooning modes.