Abstract
Plasma discharges with a negative triangularity () shape have been created in the DIII-D tokamak with a significant normalized beta () and confinement characteristic of the high confinement mode () despite the absence of an edge pressure pedestal and no edge localized modes (ELMs). These inner-wall-limited plasmas have a similar global performance as a positive triangularity () ELMing -mode discharge with the same plasma current, elongation and cross sectional area. For cases both of dominant electron cyclotron heating with and dominant neutral beam injection heating with , turbulent fluctuations over radii were reduced by 10–50% in the negative triangularity shape compared to the matching positive triangularity shape, depending on the radius and conditions.
- Received 27 November 2018
- Revised 21 January 2019
DOI:https://doi.org/10.1103/PhysRevLett.122.115001
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