title: Role of zonal flow predator-prey oscillations in triggering the transition to H-mode confinement.
abstract: Direct evidence of zonal flow (ZF) predator-prey oscillations and the synergistic roles of ZF- and equilibrium E×B flow shear in triggering the low- to high-confinement (L- to H-mode) transition in the DIII-D tokamak is presented. Periodic turbulence suppression is first observed in a narrow layer at and just inside the separatrix when the shearing rate transiently exceeds the turbulence decorrelation rate. The final transition to H mode with sustained turbulence and transport reduction is controlled by equilibrium E×B shear due to the increasing ion pressure gradient.
authors.affiliation: University of California-Los Angeles, Los Angeles, California 90095, USA.
authors.forename: L
authors.initials: L
authors.lastname: Schmitz
authors.forename: L
authors.initials: L
authors.lastname: Zeng
authors.forename: T L
authors.initials: TL
authors.lastname: Rhodes
authors.forename: J C
authors.initials: JC
authors.lastname: Hillesheim
authors.forename: E J
authors.initials: EJ
authors.lastname: Doyle
authors.forename: R J
authors.initials: RJ
authors.lastname: Groebner
authors.forename: W A
authors.initials: WA
authors.lastname: Peebles
authors.forename: K H
authors.initials: KH
authors.lastname: Burrell
authors.forename: G
authors.initials: G
authors.lastname: Wang