Size Scaling of Turbulent Transport in Magnetically Confined Plasmas

Zhang, Lin; Ethier, S.; Hahm, T. S.; Tang, W. M.

doi:10.1103/physrevlett.88.195004

Cited by 223 publications

(208 citation statements)

References 22 publications

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“…However, the turbulence intensity field itself can spread out, an effect known as turbulence spreading or turbulence penetration. [4][5][6][7][8][9] In the absence of turbulence spreading, this approach is mostly equivalent to the classical one, as the growth rates of the instabilities are large compared to transport timescales, and local saturation of the turbulence intensity field happens nearly instantaneous. By including the turbulence intensity field, this new approach has two implications.…”

Section: Introductionmentioning

confidence: 99%

Cold pulse and rotation reversals with turbulence spreading and residual stress

et al. 2016

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Articles you may be interested inTurbulence induced radial transport of toroidal momentum in boundary plasma of EAST tokamak Phys. Plasmas 23, 062309 (2016) Transport modeling based on inclusion of turbulence spreading and residual stresses shows internal rotation reversals and polarity reversal of cold pulses, with a clear indication of nonlocal transport effects due to fast spreading in the turbulence intensity field. The effects of turbulence spreading and residual stress are calculated from the gradient of the turbulence intensity. In the model presented in this paper, the flux is carried by the turbulence intensity field, which in itself is subject to radial transport effects. The pulse polarity inversion and the rotation profile reversal positions are close to the radial location of the stable/unstable transition. Both effects have no direct explanation within the framework of classical transport modeling, where the fluxes are related directly to the linear growth rates, the turbulence intensity profile is not considered and the corresponding residual stress is absent. Our simulations are in qualitative agreement with measurements from ohmically heated plasmas. Rotation reversal at a finite radius is found in situations not displaying saturated confinement, which we identify as situations where the plasma is nearly everywhere unstable. As an additional and new effect, the model predicts a perturbation of the velocity profile following a cold pulse from the edge. This allows direct experimental confirmation of both the existence of residual stress caused by turbulence intensity profiles and fundamental ideas of transport modeling presented here. Published by AIP Publishing.

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Section: Introductionmentioning

confidence: 99%

Cold pulse and rotation reversals with turbulence spreading and residual stress

et al. 2016

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“…This allows to give a description of the behaviour of the plasma at fine scales. This is physically relevant, since it was observed experimentally that the plasma undergoes a "turbulent" behaviour at such scales [14]. Let us also mention that recently, this regime was investigated in [3,5,9,12,13].…”

Section: The Finite Larmor Radius Scaling For the Vlasov-poisson Equamentioning

confidence: 99%

Effect of the polarization drift in a strongly magnetized plasma

Han-Kwan

2012

ESAIM: M2AN

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Abstract. We consider a strongly magnetized plasma described by a Vlasov-Poisson system with a large external magnetic field. The finite Larmor radius scaling allows to describe its behaviour at very fine scales. We give a new interpretation of the asymptotic equations obtained by Frénod and Sonnendrücker [SIAM J. Math. Anal. 32 (2001) 1227-1247 when the intensity of the magnetic field goes to infinity. We introduce the so-called polarization drift and show that its contribution is not negligible in the limit, contrary to what is usually said. This is due to the non linear coupling between the Vlasov and Poisson equations.Mathematics Subject Classification. 35Q83, 76X05, 82D10.

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“…However, with the advent of modern supercomputers, it was ultimately possible to give numerical demonstrations (Lin et al 2002(Lin et al , 2012) that turbulent gyrokinetic plasmas transition from Bohm to gyro-Bohm diffusion as ρ * . = ρ i /a is reduced.…”

Section: The Hasegawa-mima Equationmentioning

confidence: 99%

A tutorial introduction to the statistical theory of turbulent plasmas, a half-century after Kadomtsev’sPlasma Turbulenceand the resonance-broadening theory of Dupree and Weinstock

Krommes

2015

J. Plasma Phys.

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In honour of the 50th anniversary of the influential review/monograph on plasma turbulence by B. B. Kadomtsev as well as the seminal works of T. H. Dupree and J. Weinstock on resonance-broadening theory, an introductory tutorial is given about some highlights of the statistical-dynamical description of turbulent plasmas and fluids, including the ideas of nonlinear incoherent noise, coherent damping, and self-consistent dielectric response. The statistical closure problem is introduced. Incoherent noise and coherent damping are illustrated with a solvable model of passive advection. Self-consistency introduces turbulent polarization effects that are described by the dielectric function D. Dupree's method of using D to estimate the saturation level of turbulence is described; then it is explained why a more complete theory that includes nonlinear noise is required. The general theory is best formulated in terms of Dyson equations for the covariance C and an infinitesimal response function R, which subsumes D. An important example is the direct-interaction approximation (DIA). It is shown how to use Novikov's theorem to develop an x-space approach to the DIA that is complementary to the original k-space approach of Kraichnan. A dielectric function is defined for arbitrary quadratically nonlinear systems, including the Navier-Stokes equation, and an algorithm for determining the form of D in the DIA is sketched. The independent insights of Kadomtsev and Kraichnan about the problem of the DIA with random Galilean invariance are described. The mixing-length formula for drift-wave saturation is discussed in the context of closures that include nonlinear noise (shielded by D). The role of R in the calculation of the symmetry-breaking (zonostrophic) instability of homogeneous turbulence to the generation of inhomogeneous mean flows is addressed. The second-order cumulant expansion and the stochastic structural stability theory are also discussed in that context. Various historical research threads are mentioned and representative entry points to the literature are given. Some outstanding conceptual issues are enumerated.

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Size Scaling of Turbulent Transport in Magnetically Confined Plasmas

Cited by 223 publications

References 22 publications

Cold pulse and rotation reversals with turbulence spreading and residual stress

Cold pulse and rotation reversals with turbulence spreading and residual stress

Effect of the polarization drift in a strongly magnetized plasma

A tutorial introduction to the statistical theory of turbulent plasmas, a half-century after Kadomtsev’sPlasma Turbulenceand the resonance-broadening theory of Dupree and Weinstock

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