Progress towards sustainment of advanced tokamak modes in DIII-D

Conference · Tue Dec 01 00:00:00 EST 1998

OSTI ID:296837

Rice, B. W. ^[1]; Burrell, K. H.; Ferron, J. R. ^[2]; Greenfield, C. M.; Jackson, G. L.; Lao, L. L.; Lahaye, R. J.; Luce, T. C.; Stallard, B. W. ^[1]; Strait, E. J.; Taylor, T. S.; Turnbull, A. D.; Wade, M. R.; Synakowski, E. J. ^[3]

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1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2. General Atomics, San Diego, CA (United States); and others
3. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)

Improving confinement and beta limits simultaneously in long-pulse ELMy H-mode discharges is investigated. The product β_NH_98y serves as a useful figure-of-merit for performance, where β_N {triple_bond} β/(I/aB) and H_98y is the ratio of the thermal confinement time relative to the most recent ELMy H-mode confinement scaling established by the ITER confinement database working group. In discharges with q₀ ~ 1 (no sawteeth) and discharges with q_min > 1.5 and negative central magnetic shear, β_N ~ 2.9 and H_98y ~ 1.4 are sustained for up to 2 s. Although peaked profiles are observed, steep internal transport barriers are not present. Further increases in β_N in these discharges is limited by neoclassical tearing modes (NTM) in the positive shear region. In another recently developed regime, β_N ~ 3.8 and H_98y ~ 1.8 has been sustained during large infrequent ELMs in non-sawtoothing discharges with q₀ ~ 1. This level of performance is similar to that obtained in ELM-free regimes such as VH-mode. The limitation on β_N and pulse length in these discharges is also the onset of NTMs.

• Research Organization: General Atomics, San Diego, CA (United States); Princeton Univ., Princeton Plasma Physics Lab., NJ (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE Office of Energy Research, Washington, DC (United States)
• DOE Contract Number: AC03-89ER51114; AC02-76CH03073; AC05-96OR22464; W-7405-ENG-48
• OSTI ID: 296837
• Report Number(s): GA-A22999; CONF-981064-; ON: DE99001352; TRN: 99:002478
• Resource Relation: Conference: 17. IAEA fusion energy conference, Yokohama (Japan), 19-24 Oct 1998; Other Information: PBD: Dec 1998
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION
PLASMA CONFINEMENT
BETA RATIO
EDGE LOCALIZED MODES
PERFORMANCE
CONFINEMENT TIME
DOUBLET-3 DEVICE
OPERATION
ITER TOKAMAK