Beyond scale separation in gyrokinetic turbulence

Garbet, X.; Sarazin, Y.; Grandgirard, V.; Dif‐Pradalier, G.; Darmet, G.; Ghendrih, Ph.; Angelino, Paolo; Bertrand, Pierre; Besse, Nicolas; Gravier, Etienne; Morel, Pierre; Sonnendrücker, Éric; Crouseilles, Nicolas; Dischler, Jean‐Michel; Latu, Guillaume; Violard, Eric; Brunetti, Maura; Brunner, S.; Lapillonne, Xavier; Tran, T. M.; Villard, L.; Boulet, Mireille

doi:10.1088/0029-5515/47/9/017

Cited by 17 publications

(22 citation statements)

References 25 publications

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“…We note here that there are other full-f gyrokinetic codes under development for core plasma studies. [7][8][9] The rest of this paper is organized as follows. In Sec.…”

Section: Introductionmentioning

confidence: 99%

Compressed ion temperature gradient turbulence in diverted tokamak edge

Chang

Diamond

et al. 2009

Physics of Plasmas

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It is found from a heat-flux-driven full-f gyrokinetic particle simulation that there is ion temperature gradient ͑ITG͒ turbulence across an entire L-mode-like edge density pedestal in a diverted tokamak plasma in which the ion temperature gradient is mild without a pedestal structure, hence the normalized ion temperature gradient parameter i = ͑d log T i / dr͒ / ͑d log n / dr͒ varies strongly from high ͑Ͼ4 at density pedestal top/shoulder͒ to low ͑Ͻ2 in the density slope͒ values. Variation of density and i is in the same scale as the turbulence correlation length, compressing the turbulence in the density slope region. The resulting ion thermal flux is on the order of experimentally inferred values. The present study strongly suggests that a localized estimate of the ITG-driven i will not be valid due to the nonlocal dynamics of the compressed turbulence in an L-mode-type density slope. While the thermal transport and the temperature profile saturate quickly, the E ϫ B rotation shows a longer time damping during the turbulence. In addition, a radially in-out mean potential variation is observed.

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“…We note here that there are other full-f gyrokinetic codes under development for core plasma studies. [7][8][9] The rest of this paper is organized as follows. In Sec.…”

Section: Introductionmentioning

confidence: 99%

Compressed ion temperature gradient turbulence in diverted tokamak edge

Chang

Diamond

et al. 2009

Physics of Plasmas

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“…The appropriate framework for this turbulence is the Vlasov equation in the gyrokinetic approximation associated to the Maxwell-Gauss equation that relates the electric field to the charge density. When considering the Ion Temperature Gradient instability [9] that appears to dominate the ion heat transport, one can further assume the electron response to be adiabatic so that the plasma response is governed by the gyrokinetic Vlasov equation for the ion species. Let us now consider the linear response of such a distribution function f , to a given electrostatic perturbation, typically of the form T e φ e −iωt+i k r , (where f and φ are Fourier amplitudes of distribution function and electric potential).…”

Section: Physical Motivationsmentioning

confidence: 99%

“…Here f eq is the reference distribution function, locally Maxwellian with respect to v || and ω * is the diamagnetic frequency that contains the density and temperature gradient that drive the ITG instability [9]. T e is the electronic temperature.…”

Section: Physical Motivationsmentioning

confidence: 99%

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Barriers for the reduction of transport due to theE×Bdrift in magnetized plasmas

Tronko¹,

Vittot²,

Chandre³

et al. 2009

J. Phys. A: Math. Theor.

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We consider a 1 1 2 degrees of freedom Hamiltonian dynamical system, which models the chaotic dynamics of charged test-particles in a turbulent electric field, across the confining magnetic field in controlled thermonuclear fusion devices. The external electric field E = − ∇V is modeled by a phenomenological potential V and the magnetic field B is considered uniform. It is shown that, by introducing a small additive control term to the external electric field, it is possible to create a transport barrier for this dynamical system. The robustness of this control method is also investigated. This theoretical study indicates that alternative transport barriers can be triggered without requiring a control action on the device scale as in present Internal Transport Barriers (ITB).

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“…Neverthless, it is explained the physical assumptions needed to consider as constants the following GC quantities: P φ (corresponding to the axisymmetry angular momentum), the kinetic energy per unit mass w and the generalized pitch angle variable λ, defined as the ratio between the magnetic moment µ and w. In the text, the set (P φ , w, λ) will be referred to as the Quasi Invariants (QIs) set. The Section (2.2) provides a brief outline on how it is currently solved the problem of assigning an equilibrium distribution function in gyrokinetic codes [2,3,4,5,6,7,8]. The difficulties arising from that common procedure will be the starting point for the developing of an alternative approach.…”

Section: Introductionmentioning

confidence: 99%

From the orbit theory to a guiding center parametric equilibrium distribution function

Troia

2012

Plasma Phys. Control. Fusion

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Abstract. This work proposes a parametric equilibrium distribution function F eq to be applied to the gyrokinetic studies of the Finite Orbit Width behavior of guiding centers representing several species encountered in axisymmetric tokamak plasma, as fusion products, thermal bulk and energetic particles from Ion Cyclotron Radiation Heating and Negative Neutral Beam Injections.After the analysis of the basic results of orbit theory obtained with a particularly convenient orbit coordinates set, it is shown how the proposed F eq satisfies the two conditions that make it an equilibrium distribution function: (i) it must depend only on the constants of motion and adiabatic invariants, and (ii) the guiding centers must remain confined for suitably long time.Furthermore, the F eq can be modeled, with a proper choice of its parameters, to reproduce the most common distribution functions. A local Maxwellian distribution function is obtained for the thermal plasma in the Zero Orbit Width approximation. For the fusion α particles, F eq can also reproduce the Slowing Down (SD) distribution function. More generally, for supra-thermal particles, when external heatings are present, such as (N)NBI and ICRH, the proposed model distribution function shows similarities with the anisotropic SD and the biMaxwellian distribution functions.F eq can be used to fit experimental profiles and it could provide a useful tool for experimental and numerical data analysis. Moreover, it could help to develop analytical computations for facilitating data interpretation in the light of theoretical models. This distribution function can be easily implemented in gyrokinetic codes, where it can be used to simulate plasma also in the presence of external heating sources.

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Beyond scale separation in gyrokinetic turbulence

Cited by 17 publications

References 25 publications

Compressed ion temperature gradient turbulence in diverted tokamak edge

Compressed ion temperature gradient turbulence in diverted tokamak edge

Barriers for the reduction of transport due to theE×Bdrift in magnetized plasmas

From the orbit theory to a guiding center parametric equilibrium distribution function

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