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Koide, Y.; Kikuchi, M.; Mori, Masahiro; Tsuji, S.; Ishida, S.; Asakura, N.; Kamada, Y.; Nishitani, T.; Kawano, Y.; Hatae, T.; Fujita, T.; Fukuda, T.; Sakasai, A.; Kondoh, T.; Yoshino, R.; Neyatani, Y.

doi:10.1103/physrevlett.72.3662

Cited by 292 publications

(123 citation statements)

References 11 publications

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“…One of the first clear internal transport barriers resulting in the strong growth of the interior ion temperature gradient up to a record value of տ60 keV/m is that shown in Fig. 12 from Koide et al (1994). The edge H-mode barrier forms after the internal transport barrier at r/a ϭ0.7 and is seen by examining the change from t 3 ϭ5.75 s to t 4 ϭ6.0 s in the T i profile in the lower left frame of Fig.…”

Section: Scaling Laws Of the Ion Temperature Gradient Turbulent Trmentioning

confidence: 99%

“…In recent theory and experiments for tokamak confinement devices the combined roles of E r ϫB sheared flows and magnetic shear are known to produce enhanced confinement regimes . The improved confinement occurs over narrow radial regions giving rise to new confinement regimes with internal transport barriers (Koide et al, 1994;Levinton et al, 1995;Strait et al, 1995). The principal tools available for understanding these changes in transport are the dependence of drift-wave turbulence on the system parameters especially the magnetic shear in B(x) and mass flow shear in the hydrodynamic flow velocity u(x).…”

Section: B Drift Waves In the Laboratorymentioning

confidence: 99%

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Drift waves and transport

1999

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Drift waves occur universally in magnetized plasmas producing the dominant mechanism for the transport of particles, energy and momentum across magnetic field lines. A wealth of information obtained from quasistationary laboratory experiments for plasma confinement is reviewed for drift waves driven unstable by density gradients, temperature gradients and trapped particle effects. The modern understanding of Bohm transport and the role of sheared flows and magnetic shear in reducing the transport to the gyro-Bohm rate are explained and illustrated with large scale computer simulations. The types of mixed wave and vortex turbulence spontaneously generated in nonuniform plasmas are derived with reduced magnetized fluid descriptions. The types of theoretical descriptions reviewed include weak turbulence theory, Kolmogorov anisotropic spectral indices, and the mixing length. A number of standard turbulent diffusivity formulas are given for the various space-time scales of the drift-wave turbulent mixing. [S0034-6861(99)00803-X] CONTENTS

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Section: Scaling Laws Of the Ion Temperature Gradient Turbulent Trmentioning

confidence: 99%

Section: B Drift Waves In the Laboratorymentioning

confidence: 99%

Drift waves and transport

1999

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“…While it is often assumed that the lack of poloidal symmetry within a tokamak device will result in the plasma poloidal flow being dragged back to its neoclassical level, numerous counterexamples in the vicinity of internal transport barriers can be identified within the experimental literature. [5][6][7] Furthermore, recent experiments at DIII-D indicate that deviations in the magnitude as well as direction of the poloidal rotation of impurity ions from that predicted by neoclassical theory can be present throughout the plasma volume. 8 Within the above studies, measured poloidal flows have been observed to deviate from neoclassical predictions by as much as an order of magnitude.…”

Section: Introductionmentioning

confidence: 99%

Poloidal rotation and its relation to the potential vorticity flux

et al. 2010

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A kinetic generalization of a Taylor identity appropriate to a strongly magnetized plasma is derived. This relation provides an explicit link between the radial mixing of a four-dimensional ͑4D͒ gyrocenter fluid and the poloidal Reynolds stress. This kinetic analog of a Taylor identity is subsequently utilized to link the turbulent transport of poloidal momentum to the mixing of potential vorticity. A quasilinear calculation of the flux of potential vorticity is carried out, yielding diffusive, turbulent equipartition, and thermoelectric convective components. Self-consistency is enforced via the quasineutrality relation, revealing that for the case of a stationary small amplitude wave population, deviations from neoclassical predictions of poloidal rotation can be closely linked to the growth/damping profiles of the underlying drift wave microturbulence.

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“…Wolf 1 has provided a comprehensive review of the experimental results and current understanding of these phenomena. Most experiments have achieved internal transport barriers (ITBs) by adding auxiliary heating 2,3,4,5,6 beyond some threshold value resulting in distinct changes in the heat, momentum, or particle transport from one region of the plasma to another. It has also been demonstrated that reversal of magnetic shear by use of current modification by lower hybrid current drive 7 or electron cyclotron current drive 8 encourages ITB development.…”

Section: Introductionmentioning

confidence: 99%

Control of internal transport barriers on Alcator C-Mod

et al. 2004

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Recent studies of internal transport and double transport barrier regimes in Alcator C-Mod [I. H. Hutchinson, et al., Phys. Plasmas 1, 1511] have explored the limits for forming, maintaining, and controlling these plasmas. C-Mod provides a unique platform for studying such discharges: the ions and electrons are tightly coupled by collisions and the plasma has no internal particle or momentum sources. The double-barrier mode comprised of an edge barrier with an internal transport barrier (ITB) can be induced at will using off-axis ion cyclotron range of frequency (ICRF) injection on either the low or high field side of the plasma with either of the available ICRF frequencies (70 or 80 MHz). When enhanced D α high confinement mode (EDA H-mode) is accessed in Ohmic plasmas, the double barrier ITB forms spontaneously if the Hmode is sustained for ~2 energy confinement times. The ITBs formed in both Ohmic and ICRF heated plasmas are quite similar regardless of the trigger method. They are characterized by strong central peaking of the electron density, and reduction of the core particle and energy transport. Control of impurity influx and heating of the core plasma in the presence of the ITB have been achieved with the addition of central ICRF power in both Ohmic H-mode and ICRF induced ITBs. The radial location of the particle transport is dependent on the toroidal magnetic field but not on the location of the ICRF resonance. A narrow region of decreased electron thermal transport, as determined by sawtooth heat pulse analysis, is found in these plasmas as well. Transport analysis indicates that reduction of the particle diffusivity in the barrier region allows the neoclassical pinch to drive the density and impurity accumulation in the plasma center. Examination of the gyrokinetic stability at the trigger time for the ITB suggests that the density and temperature profiles are inherently stable to ion temperature gradient (ITG) and trapped electron (TEM) modes in the core inside of the ITB location.

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Internal transport barrier onq=3 surface and poloidal plasma spin up in JT-60U high-βpdischarges

Cited by 292 publications

References 11 publications

Drift waves and transport

Drift waves and transport

Poloidal rotation and its relation to the potential vorticity flux

Control of internal transport barriers on Alcator C-Mod

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