Results from core-edge experiments in high Power, high performance plasmas on DIII-D. (August 2017)

• Record Type: Journal Article
• Authors: Petrie, T.W.; Fenstermacher, M.E.; Holcomb, C.T.; Osborne, T.H.; Allen, S.L.; Ferron, J.R.; Guo, H.Y.; Lasnier, C.J.; Leonard, A.W.; Luce, T.C.; Makowski, M.A.; McLean, A.G.; Pace, D.C.; Solomon, W.M.; Turco, F.; VanZeeland, M.A.; Watkins, J.G.
• Is Part Of: Nuclear materials and energy. Volume 12(2017)
• Page Start: 1141
• Page End: 1145
• Publication Date: 2017-08
• Subjects: DIII-D -- Divertor geometry -- Gas injection and fueling -- Impurity sources -- Power deposition; Nuclear energy -- Periodicals; Nuclear fuels -- Periodicals; Nuclear reactors -- Materials -- Periodicals; Radioactive substances -- Periodicals; 621.4833
• DOI: 10.1016/j.nme.2016.10.029
• Languages: English
• ISSNs: 2352-1791

Abstract

Highlights: Peaked heat flux dependence on IP and PSOL for DIII-D DNDs consistent with ITPA SNs. Gas injection can improve τE in highly powered DND plasmas. "Semi-slot" divertor configuration on DIII-D shows significant heat flux reduction. Abstract: Significant challenges to reducing divertor heat flux in highly powered near-double null divertor (DND) hybrid plasmas, while still maintaining both high performance metrics and low enough density for application of RF heating, are identified. For these DNDs on DIII-D, the scaling of the peak heat flux at the outer target (q⊥ P ) ∝ [PSOL x IP ] 0.92 for PSOL = 8−19 MW and IP = 1.0–1.4 MA, and is consistent with standard ITPA scaling for single-null H-mode plasmas. Two divertor heat flux reduction methods were tested. First, applying the puff-and-pump radiating divertor to DIII-D plasmas may be problematical at high power and H98 (≥ 1.5) due to improvement in confinement time with deuterium gas puffing which can lead to unacceptably high core density under certain conditions. Second, q⊥ P for these high performance DNDs was reduced by ≈35% when an open divertor is closed on the common flux side of the outer divertor target ("semi-slot") but also that heating near the slot opening is a significant source for impurity contamination of the core.