title: Reduction of edge-localized mode intensity using high-repetition-rate pellet injection in tokamak H-mode plasmas.
abstract: High repetition rate injection of deuterium pellets from the low-field side (LFS) of the DIII-D tokamak is shown to trigger high-frequency edge-localized modes (ELMs) at up to 12× the low natural ELM frequency in H-mode deuterium plasmas designed to match the ITER baseline configuration in shape, normalized beta, and input power just above the H-mode threshold. The pellet size, velocity, and injection location were chosen to limit penetration to the outer 10% of the plasma. The resulting perturbations to the plasma density and energy confinement time are thus minimal (<10%). The triggered ELMs occur at much lower normalized pedestal pressure than the natural ELMs, suggesting that the pellet injection excites a localized high-n instability. Triggered ELMs produce up to 12× lower energy and particle fluxes to the divertor, and result in a strong decrease in plasma core impurity density. These results show for the first time that shallow, LFS pellet injection can dramatically accelerate the ELM cycle and reduce ELM energy fluxes on plasma facing components, and is a viable technique for real-time control of ELMs in ITER.
authors.affiliation: Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-8072, USA.
authors.forename: L R
authors.initials: LR
authors.lastname: Baylor
authors.affiliation: Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-8072, USA.
authors.forename: N
authors.initials: N
authors.lastname: Commaux
authors.affiliation: Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-8072, USA.
authors.forename: T C
authors.initials: TC
authors.lastname: Jernigan
authors.affiliation: General Atomics, San Diego, California 92186-5608, USA.
authors.forename: N H
authors.initials: NH
authors.lastname: Brooks
authors.affiliation: Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-8072, USA.
authors.forename: S K
authors.initials: SK
authors.lastname: Combs
authors.affiliation: General Atomics, San Diego, California 92186-5608, USA.
authors.forename: T E
authors.initials: TE
authors.lastname: Evans
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
authors.forename: M E
authors.initials: ME
authors.lastname: Fenstermacher
authors.affiliation: Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-8072, USA.
authors.forename: R C
authors.initials: RC
authors.lastname: Isler
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
authors.forename: C J
authors.initials: CJ
authors.lastname: Lasnier
authors.affiliation: Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-8072, USA.
authors.forename: S J
authors.initials: SJ
authors.lastname: Meitner
authors.affiliation: University of California San Diego, La Jolla, California 92093-0319, USA.
authors.forename: R A
authors.initials: RA
authors.lastname: Moyer
authors.affiliation: General Atomics, San Diego, California 92186-5608, USA.
authors.forename: T H
authors.initials: TH
authors.lastname: Osborne
authors.affiliation: General Atomics, San Diego, California 92186-5608, USA.
authors.forename: P B
authors.initials: PB
authors.lastname: Parks
authors.affiliation: General Atomics, San Diego, California 92186-5608, USA.
authors.forename: P B
authors.initials: PB
authors.lastname: Snyder
authors.affiliation: General Atomics, San Diego, California 92186-5608, USA.
authors.forename: E J
authors.initials: EJ
authors.lastname: Strait
authors.affiliation: Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-8072, USA.
authors.forename: E A
authors.initials: EA
authors.lastname: Unterberg
authors.affiliation: ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance Cedex, France.
authors.forename: A
authors.initials: A
authors.lastname: Loarte