Fine-Scale Zonal Flow Suppression of Electron Temperature Gradient Turbulence

Parker, Scott; Kohut, Jiri; Chen, Y.; Lin, Z.; Hinton, F. L.; Lee, W. W.

doi:10.1063/1.2404551

Cited by 11 publications

(14 citation statements)

References 14 publications

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“…Of particular interest is the effect of zonal flows on nonlinear energy and particle transport as well as nonlinear saturation level. The zonal flow is self-consistently generated by drift wave turbulence through nonlinear E × B coupling and is known to be important in regulating transport in ion-temperature-gradient driven turbulence [23,24,25,26], and may also be important in electron-temperature-gradient driven turbulence as well [27]. However, for TEM-driven turbulence, there is not yet a definitive theory or community consensus with regard to the role that zonal flow plays, if any.…”

Section: Introductionmentioning

confidence: 99%

Gyrokinetic δf particle simulation of trapped electron mode driven turbulence

Lang¹,

Chen²,

Parker³

2007

Physics of Plasmas

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The linear instabilities and nonlinear transport driven by collisionless trapped electron modes (CTEM) are systematically investigated using three-dimensional gyrokinetic δf particle-in-cell simulations. Scalings with local plasma parameters are presented. Simulation results are compared with previous simulations and theoretical predictions. The magnetic shear is found to be linearly stabilizing, but nonlinearly the transport level increases with increasing magnetic shear. This is explained by the changes in radial eddy correlation lengths caused by toroidal coupling. The effect of zonal flows in suppressing the nonlinear CTEM transport is demonstrated to depend on electron temperature gradient and electron to ion temperature ratio. The suppression effect is consistent with the rate of shearing on turbulent eddies due to zonal flows and the radial sprectra broadening. Strong geodesic acoustic modes (GAM) are generated along with zonal flows.

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Section: Introductionmentioning

confidence: 99%

Gyrokinetic δf particle simulation of trapped electron mode driven turbulence

Lang¹,

Chen²,

Parker³

2007

Physics of Plasmas

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“…1,2 The bulk of heat and particle transport in such systems is typically driven by residual, non-MHD, small-scale modes, which produce turbulent convection within the plasma. The zonal flows in these systems have a stabilizing impact on the turbulence that can become dramatically strong as the system approaches marginal stability: turbulence suppression due to zonal flows has been observed, for example, in ion temperature gradient, [3][4][5] electron temperature gradient, 6 trapped electron, 7,8 and entropy 9,10 mode turbulence. In these cases the turbulence-driving modes can be virtually eliminated by zonal flows that are themselves weak enough to be stable to Kelvin-Helmholtz-like instabilities and other modes.…”

Section: Introductionmentioning

confidence: 99%

Collisional damping of zonal flows due to finite Larmor radius effects

Ricci¹,

Rogers²,

Dorland³

2010

Physics of Plasmas

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The collisional damping of seeded E ϫ B zonal flows on the ion Larmor radius scale is studied using a gyrokinetic model. The focus is on flow damping due to finite Larmor radius effects, which cause a v ʈ / v anisotropy of the ion distribution function that is damped by ion-ion collisions. The gyrokinetic equations are solved in a slab geometry with no gradients or curvature, and a gyroaveraged Lorentz collision operator that conserves particle number, momentum, and energy is used. The solution of the gyrokinetic equations explores the dependence of the damping rate on the wavelength of the flows and the impact of the collisions on the ion distribution function. These numerical results can be used as a benchmark test during the implementation of finite Larmor radius effects in the collision operator of gyrokinetic codes.

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“…Particularly, the strong coupling with zonal flow and e-GAM was observed in global ETG simulations of NSTX plasma [41] as discussed above. In addition, the dependence of ETG turbulence on collisionality has been observed in particle-in-cell gyro-kinetic simulations [71] and more recently in [58]. Here we review on this dependence from a collisionality scan carried out using low-beta NSTX NBI-heated H-mode plasmas with ρ e , β e and q 95 kept approximately constant.…”

Section: × E B Shear Dependencementioning

confidence: 84%

Recent progress in understanding electron thermal transport in NSTX

Ren¹,

Белова²,

Gorelenkov³

et al. 2017

Nucl. Fusion

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The anomalous level of electron thermal transport inferred in magnetically confined configurations is one of the most challenging problems for the ultimate realization of fusion power using toroidal devices: tokamaks, spherical tori and stellarators. It is generally believed that plasma instabilities driven by the abundant free energy in fusion plasmas are responsible for the electron thermal transport. The National Spherical Torus eXperiment (NSTX) (Ono et al 2000 Nucl. Fusion 40 557) provides a unique laboratory for studying plasma instabilities and their relation to electron thermal transport due to its low toroidal field, high plasma beta, low aspect ratio and large × E B flow shear. Recent findings on NSTX have shown that multiple instabilities are required to explain observed electron thermal transport, given the wide range of equilibrium parameters due to different operational scenarios and radial regions in fusion plasmas. Here we review the recent progresses in understanding anomalous electron thermal transport in NSTX and focus on mechanisms that could drive electron thermal transport in the core region. The synergy between experiment and theoretical/numerical modeling is essential to achieving these progresses. The plans for newly commissioned NSTX-Upgrade will also be discussed.

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Fine-Scale Zonal Flow Suppression of Electron Temperature Gradient Turbulence

Cited by 11 publications

References 14 publications

Gyrokinetic δf particle simulation of trapped electron mode driven turbulence

Gyrokinetic δf particle simulation of trapped electron mode driven turbulence

Collisional damping of zonal flows due to finite Larmor radius effects

Recent progress in understanding electron thermal transport in NSTX

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