Plasma Performance and Operational Boundaries Without ELMs in DIII-D

ASDEX Upgrade Seminar

  • Date: Jul 1, 2020
  • Time: 04:00 PM - 05:30 PM (Local Time Germany)
  • Speaker: Carlos Paz Soldan
  • Location: Garching
  • Room: Zoom
  • Host: IPP
C Paz-Soldan: Plasma Performance and Operational Boundaries Without ELMs in DIII-D

Abstract:
A comprehensive database of stationary DIII-D plasmas without ELMs compares all no-ELM regimes types found in DIII-D: RMP-ELM suppression, QH-mode (incl. wide-ped), I-mode, EDA H-mode, regular L-mode, and negative triangularity L-mode (neg-D). Absolute plasma performance measured by Lawson product (<p>tE), increases in all regimes with IaB and injected power. These abscissa are often limited by the ELM, not hardware. Normalizing <p>tE to IaB, comparable performance is found for QH and RMP plasmas though the pedestal pressure (pped = 2 pe,ped) is very different. pped in RMP plasmas is roughly constant, with the best performance found with a high core <p> fraction alongside high core rotation, suggestive of an ExB shear turbulence suppression mechanism. pped of QH plasmas is significantly higher than RMP, and QH performance does not correlate with core rotation. However, the best QH pped are found with high carbon fraction. Performance of neg-D is below RMP & QH, owing to lower achieved elongation, IaB, and resultant confinement. The QH, EDA, L, and neg-D scenarios have approached divertor-friendly high density conditions, though neg-D does so with highest core performance, owing to its compatibility with both high power and density.
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