2019_EJRNL_PP_M__E__AUSTIN_1.pdf
Terbatas Ratnasari
» ITB
Terbatas Ratnasari
» ITB
Plasma discharges with a negative triangularity (? ¼ ?0.4) shape have been created in the DIII-D
tokamak with a significant normalized beta (?N ¼ 2.7) and confinement characteristic of the high
confinement mode (H98y2 ¼ 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 (? ¼ þ0.4) ELMing H-mode discharge with the same plasma current, elongation and cross
sectional area. For cases both of dominant electron cyclotron heating with Te=Ti > 1 and dominant neutral
beam injection heating with Te=Ti ¼ 1, turbulent fluctuations over radii 0.5 < ? < 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.