Edge-Localized-Mode Suppression through Density-Profile Modification with Lithium-Wall Coatings in the National Spherical Torus Experiment
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 or 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.
- Publication:
-
Physical Review Letters
- Pub Date:
- August 2009
- DOI:
- 10.1103/PhysRevLett.103.075001
- Bibcode:
- 2009PhRvL.103g5001M
- Keywords:
-
- 52.55.Fa;
- 52.40.Hf;
- Tokamaks spherical tokamaks;
- Plasma-material interactions;
- boundary layer effects