Vorticity dynamics, drift wave turbulence, and zonal flows: a look back and a look ahead

Diamond, P. H.; Hasegawa, Akira; Mima, K.

doi:10.1088/0741-3335/53/12/124001

Cited by 77 publications

(56 citation statements)

References 79 publications

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“…Drift waves, on the other hand, arise from E Â B convection of the electron density profile, and they become destabilized in the presence of a non-adiabatic electron response, due to, e.g., resistivity or finite electron mass. [19][20][21][22][23] As a matter of fact, in agreement with experimental results, low-frequency non-linear electromagnetic models (both fluid and gyrofluid) have identified the edge turbulent regimes, [3][4][5][6]24 showing that DW and BM instabilities determine the plasma turbulent dynamics. The relative importance of each mode, however, is still unclear, and non-linear simulations of edge and SOL turbulent dynamics have addressed both instabilities.…”

Section: Introductionsupporting

confidence: 59%

Low-frequency linear-mode regimes in the tokamak scrape-off layer

et al. 2012

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Oblique electron-cyclotron-emission radial and phase detector of rotating magnetic islands applied to alignment and modulation of electron-cyclotron-current-drive for neoclassical tearing mode stabilization Rev. Sci. Instrum. 83, 103507 (2012) Toroidal rotation of multiple species of ions in tokamak plasma driven by lower-hybrid-waves Phys. Plasmas 19, 102505 (2012) Motivated by the wide range of physical parameters characterizing the scrape-off layer (SOL) of existing tokamaks, the regimes of low-frequency linear instabilities in the SOL are identified by numerical and analytical calculations based on the linear, drift-reduced Braginskii equations, with cold ions. The focus is put on ballooning modes and drift wave instabilities, i.e., their resistive, inertial, and ideal branches. A systematic study of each instability is performed, and the parameter space region where they dominate is identified. It is found that the drift waves dominate at high R=L n , while the ballooning modes at low R=L n ; the relative influence of resistive and inertial effects is discussed. Electromagnetic effects suppress the drift waves and, when the threshold for ideal stability is overcome, the ideal ballooning mode develops. Our analysis is a first stage tool for the understanding of turbulence in the tokamak SOL, necessary to interpret the results of non-linear simulations. [http://dx.doi.org/10.1063/ 1.4758809]

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Section: Introductionsupporting

confidence: 59%

Low-frequency linear-mode regimes in the tokamak scrape-off layer

et al. 2012

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“…These quantities are defined by Eqs. (16), (17), and (18) and verified by the conservation law (24).…”

Section: B Numerical Results In the Interchange Regimementioning

confidence: 69%

Shear-flow trapped-ion-mode interaction revisited. I. Influence of low-frequency zonal flow on ion-temperature-gradient driven turbulence

Ghizzo

Palermo

2015

Physics of Plasmas

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Collisionless trapped ion modes (CTIMs) turbulence exhibits a rich variety of zonal flow physics. The coupling of CTIMs with shear flow driven by the Kelvin-Helmholtz (KH) instability has been investigated. The work explores the parametric excitation of zonal flow modified by wave-particle interactions leading to a new type of resonant low-frequency zonal flow. The KH-CTIM interaction on zonal flow growth and its feedback on turbulence is investigated using semi-Lagrangian gyrokinetic Vlasov simulations based on a Hamiltonian reduction technique, where both fast scales (cyclotron plus bounce motions) are gyro-averaged. V C 2015 AIP Publishing LLC.

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“…21 The turbulence quenching sheared flows in a plasma are identified as the E Â B-flows. [22][23][24] These flow shears are indeed observed as driven by Reynolds stress in the form of zonal flows, 3,25 and externally driven by probes generating a radial electric field, 26 and by various other mechanisms. This quenching mechanism is frequently modelled 13,14 as an effective diffusivity depending on the E Â Bflow shear,…”

Section: Transport Model For the L-h Transitionmentioning

confidence: 95%

“…Although this very beneficial, L-to H-mode transition has been seen in most present day tokamaks, all physical mechanisms which are relevant to these transitions are still not fully identified. 2 Many different models have been introduced 3,4 to explain the reduction of transport due to the L-H transition. Some models, based on sets of 0-dimensional dynamical equations, are well capable of qualitatively describing global temporal evolution behaviour around L-H transitions.…”

Section: Introductionmentioning

confidence: 99%

Bifurcation theory of a one-dimensional transport model for the L-H transition

2013

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Transitions between low and high-confinement (L-H transitions) in magnetically confined plasmas can appear as three qualitatively different types: sharp, smooth, and oscillatory. Bifurcation analysis unravels these possible transition types and how they are situated in parameter space. In this paper the bifurcation analysis is applied to a 1-dimensional model for the radial transport of energy and density near the edge of magnetically confined plasmas. This phenomenological L-H transition model describes the reduction of the turbulent transport by E Â B-flow shear selfconsistently with the evolution of the radial electric field. Therewith, the exact parameter space, including the threshold values of the control parameters, of the possible L-H transitions in the model is determined. Furthermore, a generalised equal area rule is derived to describe the evolution of the transport barrier in space and time self-consistently. Applying this newly developed rule to the model analysed in this paper reveals a naturally occurring transition to an extra wide transport barrier that may correspond to the improved confinement known as the very-high-confinement mode. [http://dx

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Vorticity dynamics, drift wave turbulence, and zonal flows: a look back and a look ahead

Cited by 77 publications

References 79 publications

Low-frequency linear-mode regimes in the tokamak scrape-off layer

Low-frequency linear-mode regimes in the tokamak scrape-off layer

Shear-flow trapped-ion-mode interaction revisited. I. Influence of low-frequency zonal flow on ion-temperature-gradient driven turbulence

Bifurcation theory of a one-dimensional transport model for the L-H transition

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