Achievement of Reactor-Relevant Performance in Negative Triangularity Shape in the DIII-D Tokamak

M E Austin; A Marinoni; M L Walker; M W Brookman; J S deGrassie; A W Hyatt; G R McKee; C C Petty; T L Rhodes; S P Smith; C Sung; K E Thome; A D Turnbull

doi:10.1103/PhysRevLett.122.115001

Achievement of Reactor-Relevant Performance in Negative Triangularity Shape in the DIII-D Tokamak

Phys Rev Lett. 2019 Mar 22;122(11):115001. doi: 10.1103/PhysRevLett.122.115001.

Authors

M E Austin¹, A Marinoni², M L Walker³, M W Brookman³, J S deGrassie³, A W Hyatt³, G R McKee⁴, C C Petty³, T L Rhodes⁵, S P Smith³, C Sung⁶, K E Thome³, A D Turnbull³

Affiliations

¹ The University of Texas at Austin, Austin, Texas 78712, USA.
² MIT-Plasma Science and Fusion Center, Cambridge, Massachusetts 02139, USA.
³ General Atomics, San Diego, California 92186, USA.
⁴ University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
⁵ University of California-Los Angeles, Los Angeles, California 90095, USA.
⁶ Lam Research Corp., Fremont, California 94538, USA.

PMID: 30951344
DOI: 10.1103/PhysRevLett.122.115001

Abstract

Plasma discharges with a negative triangularity (δ=-0.4) shape have been created in the DIII-D tokamak with a significant normalized beta (β_{N}=2.7) and confinement characteristic of the high confinement mode (H_{98y2}=1.2) 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 (δ=+0.4) ELMing H-mode discharge with the same plasma current, elongation and cross sectional area. For cases both of dominant electron cyclotron heating with T_{e}/T_{i}>1 and dominant neutral beam injection heating with T_{e}/T_{i}=1, turbulent fluctuations over radii 0.5<ρ<0.9 were reduced by 10-50% in the negative triangularity shape compared to the matching positive triangularity shape, depending on the radius and conditions.