The quiescent H-mode regime for high performance edge localized mode-stable operation in future burning plasmas

Journal Article · Fri May 15 00:00:00 EDT 2015 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.4921406· OSTI ID:22410394

Burrell, K. H.; Meneghini, O.; Osborne, T. H.; Paz-Soldan, C.; Smith, S. P.; Snyder, P. B.; Turnbull, A. D. ^[1]; Eldon, D.; Grierson, B. A.; Solomon, W. M. ^[2]; Hanson, J. M. ^[3]; Holland, C. ^[4]; Huijsmans, G. T. A.; Liu, F.; Loarte, A. ^[5]; Zeng, L. ^[6]

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1. General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States)
2. Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543-0451 (United States)
3. Columbia University, 2960 Broadway, New York, New York 10027-6900 (United States)
4. University of California San Diego, 9500 Gilman Dr., La Jolla, California 92093-0417 (United States)
5. ITER Organization, Route de Vinon sur Verdon, 13067 St Paul Lez Durance (France)
6. University of California Los Angeles, P.O. Box 957099, Los Angeles, California 90095-7099 (United States)

For the first time, DIII-D experiments have achieved stationary quiescent H-mode (QH-mode) operation for many energy confinement times at simultaneous ITER-relevant values of beta, confinement, and safety factor, in an ITER-like shape. QH-mode provides excellent energy confinement, even at very low plasma rotation, while operating without edge localized modes (ELMs) and with strong impurity transport via the benign edge harmonic oscillation (EHO). By tailoring the plasma shape to improve the edge stability, the QH-mode operating space has also been extended to densities exceeding 80% of the Greenwald limit, overcoming the long-standing low-density limit of QH-mode operation. In the theory, the density range over which the plasma encounters the kink-peeling boundary widens as the plasma cross-section shaping is increased, thus increasing the QH-mode density threshold. The DIII-D results are in excellent agreement with these predictions, and nonlinear magnetohydrodynamic analysis of reconstructed QH-mode equilibria shows unstable low n kink-peeling modes growing to a saturated level, consistent with the theoretical picture of the EHO. Furthermore, high density operation in the QH-mode regime has opened a path to a new, previously predicted region of parameter space, named “Super H-mode” because it is characterized by very high pedestals that can be more than a factor of two above the peeling-ballooning stability limit for similar ELMing H-mode discharges at the same density.

• OSTI ID: 22410394
• Journal Information: Physics of Plasmas, Vol. 22, Issue 5; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
BALLOONING INSTABILITY
DOUBLET-3 DEVICE
EDGE LOCALIZED MODES
HARMONICS
H-MODE PLASMA CONFINEMENT
ITER TOKAMAK
MAGNETOHYDRODYNAMICS
NONLINEAR PROBLEMS
PLASMA
PLASMA DENSITY
PLASMA IMPURITIES
ROTATING PLASMA
SAFETY
SHAPE