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Title: Reduction of edge localized mode intensity on DIII-D by on-demand triggering with high frequency pellet injection and implications for ITER

The injection of small deuterium pellets at high repetition rates up to 12× the natural edge localized mode (ELM) frequency has been used to trigger high-frequency ELMs in otherwise low natural ELM frequency H-mode deuterium discharges in the DIII-D tokamak [J. L. Luxon and L. G. Davis, Fusion Technol. 8, 441 (1985)]. The resulting pellet-triggered ELMs result in up to 12× lower energy and particle fluxes to the divertor than the natural ELMs. The plasma global energy confinement and density are not strongly affected by the pellet perturbations. The plasma core impurity density is strongly reduced with the application of the pellets. These experiments were performed with pellets injected from the low field side pellet in plasmas designed to match the ITER baseline configuration in shape and normalized β operation with input heating power just above the H-mode power threshold. Nonlinear MHD simulations of the injected pellets show that destabilization of ballooning modes by a local pressure perturbation is responsible for the pellet ELM triggering. This strongly reduced ELM intensity shows promise for exploitation in ITER to control ELM size while maintaining high plasma purity and performance.
Authors:
; ; ; ; ; ;  [1] ; ; ; ; ; ; ;  [2] ; ;  [3] ;  [4] ; ; ;  [5]
  1. Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, Tennessee 37830-6169 (United States)
  2. General Atomics, PO Box 85608, San Diego, California 92186-5608 (United States)
  3. Lawrence Livermore National Laboratory, 700 East Ave, Livermore, California 94550 (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, 13115 St. Paul Lez Durance (France)
Publication Date:
OSTI Identifier:
22227915
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 20; Journal Issue: 8; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; BALLOONING INSTABILITY; DEUTERIUM; DISTURBANCES; DIVERTORS; DOUBLET-3 DEVICE; EDGE LOCALIZED MODES; HIGH-FREQUENCY DISCHARGES; H-MODE PLASMA CONFINEMENT; ITER TOKAMAK; MAGNETOHYDRODYNAMICS; PELLET INJECTION; PLASMA BEAM INJECTION; PLASMA DENSITY; PLASMA IMPURITIES; PLASMA SIMULATION