Reduction of Edge Localized Mode Intensity on DIII-D by On-demand triggering with High Frequency Pellet Injection and Implications for ITER

Journal Article · Tue Jan 01 00:00:00 EST 2013 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.4818772· OSTI ID:1093100

Baylor, Larry R ^[1]; Commaux, Nicolas JC ^[1]; Jernigan, T. C. ^[2]; Meitner, Steven J ^[1]; Combs, Stephen Kirk ^[1]; Isler, Ralph C ^[1]; Unterberg, Ezekial A ^[1]; Brooks, N. H. ^[3]; Evans, T. E. ^[3]; Leonard, A. W. ^[4]; Osborne, T. H. ^[4]; Parks, P. B. ^[4]; Snyder, P. B. ^[4]; Strait, E. J. ^[4]; Fenstermacher, M. E. ^[5]; Lasnier, C. J. ^[5]; Moyer, R. A. ^[6]; Loarte, A. ^[7]; Huijsmans, G. T.A. ^[8]; Futantani, S. ^[8]

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1. ORNL
2. Oak Ridge National Laboratory (ORNL)
3. General Atomics, San Diego
4. General Atomics
5. Lawrence Livermore National Laboratory (LLNL)
6. University of California, San Diego
7. ITER Organization, Cadarache, France
8. ITER Organization, Saint Paul Lez Durance, France

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 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.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: DE-AC05-00OR22725
• OSTI ID: 1093100
• Journal Information: Physics of Plasmas, Vol. 20, Issue 8; ISSN 1070-664X
• Publisher: American Institute of Physics (AIP)
• Country of Publication: United States
• Language: English