Publication Type
Journal
Journal Name
Physical Review Letters
Publication Date
Page Numbers
1 to 10
Volume
103
Abstract
Reduction or elimination of edge localized modes (ELMs) while maintaining high confinement is essential for future fusion devices, e.g. the ITER. An ELM-free regime was recently obtained in the National Spherical Torus Experiment, following lithium (li) evaporation onto the plasma facing components. Edge stability calculations indicate that the pre-li discharges were unstable to low-n peeling/ballooning modes, while broader pressure profiles stabilized the post-li discharges. Normalized energy confinement increased by 50% post-li, with no sign of ELMs up to the global stability limit.