title: Low-to-High Confinement Transition Mediated by Turbulence Radial Wave Number Spectral Shift in a Fusion Plasma.
abstract: A new model for the low-to-high (L-H) confinement transition has been developed based on a new paradigm for turbulence suppression by velocity shear [G. M. Staebler et al., Phys. Rev. Lett. 110, 055003 (2013)]. The model indicates that the L-H transition can be mediated by a shift in the radial wave number spectrum of turbulence, as evidenced here, for the first time, by the direct observation of a turbulence radial wave number spectral shift and turbulence structure tilting prior to the L-H transition at tokamak edge by direct probing. This new mechanism does not require a pretransition overshoot in the turbulent Reynolds stress, shunting turbulence energy to zonal flows for turbulence suppression as demonstrated in the experiment.
authors.affiliation: Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China.
authors.forename: G S
authors.initials: GS
authors.lastname: Xu
authors.affiliation: Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China.
authors.forename: B N
authors.initials: BN
authors.lastname: Wan
authors.affiliation: Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China.
authors.forename: H Q
authors.initials: HQ
authors.lastname: Wang
authors.affiliation: Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China.|General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA.
authors.forename: H Y
authors.initials: HY
authors.lastname: Guo
authors.affiliation: PPFE, Department of Physics, Technical University of Denmark, DK 2800 Kongens Lyngby, Denmark.
authors.forename: V
authors.initials: V
authors.lastname: Naulin
authors.affiliation: PPFE, Department of Physics, Technical University of Denmark, DK 2800 Kongens Lyngby, Denmark.
authors.forename: J Juul
authors.initials: JJ
authors.lastname: Rasmussen
authors.affiliation: PPFE, Department of Physics, Technical University of Denmark, DK 2800 Kongens Lyngby, Denmark.
authors.forename: A H
authors.initials: AH
authors.lastname: Nielsen
authors.affiliation: Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China.
authors.forename: X Q
authors.initials: XQ
authors.lastname: Wu
authors.affiliation: Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China.|PPFE, Department of Physics, Technical University of Denmark, DK 2800 Kongens Lyngby, Denmark.
authors.forename: N
authors.initials: N
authors.lastname: Yan
authors.affiliation: Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China.
authors.forename: L
authors.initials: L
authors.lastname: Chen
authors.affiliation: Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China.
authors.forename: L M
authors.initials: LM
authors.lastname: Shao
authors.affiliation: Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China.
authors.forename: R
authors.initials: R
authors.lastname: Chen
authors.affiliation: Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China.
authors.forename: L
authors.initials: L
authors.lastname: Wang
authors.affiliation: Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China.
authors.forename: W
authors.initials: W
authors.lastname: Zhang