Turbulence in the TORE SUPRA Tokamak: Measurements and Validation of Nonlinear Simulations

Casati, A.; Gerbaud, T.; Hennequin, Pascale; Bourdelle, C.; Candy, J.; Clairet, F.; Garbet, X.; Grandgirard, V.; Gürcan, Ö. D.; Heuraux, S.; Hoang, G. T.; Honoré, Cyrille; Imbeaux, F.; Sabot, R.; Sarazin, Y.; Vermare, Laure; Waltz, R. E.

doi:10.1103/physrevlett.102.165005

Cited by 74 publications

(78 citation statements)

References 16 publications

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“…While good agreement has been found between electric field fluctuations in both frequency and amplitude in global simulations [32] and density turbulence level in both directions perpendicular to the magnetic field [29], mixed results have been obtained when comparing the radial dependence of density and temperature fluctuation levels [6,15,28]. The scarcity of results, in particular of scale-resolved comparisons [6,15], indicates that these studies are demanding on both experimental and simulation sides, all the more reason to dedicate more effort into validation of gyrokinetic models and their predictions through comparison with microturbulence measurements.…”

Section: Introductionmentioning

confidence: 67%

“…They have been successfully applied to describe core transport properties like profile stiffness [15][16][17][18][19][20] and (internal) transport barriers [21]. However, while substantial effort has been dedicated to the verification of the codes [22][23][24][25][26][27], a careful validation including measurements of microturbulence and non-linear simulations, which has to be applied to many different plasma regimes, has only started in the last years [15,[28][29][30][31][32][33][34]. The definition of the terms verification and validation are used as in Refs.…”

Section: Introductionmentioning

confidence: 99%

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Core turbulence behavior moving from ion-temperature-gradient regime towards trapped-electron-mode regime in the ASDEX Upgrade tokamak and comparison with gyrokinetic simulation

et al. 2015

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Additional electron cyclotron resonance heating (ECRH) is used in an ion-temperature-gradient instability (ITG) dominated regime to increase R/L Te in order to approach the trapped-electron-mode instability (TEM) regime. The radial ECRH deposition location determines to a large degree the effect on R/L Te . Accompanying scale-selective turbulence measurements at perpendicular wavenumbers between k ⊥ = 4 -18 cm −1 (k ⊥ ρ s = 0.7 -4.2) show a pronounced increase of large-scale density fluctuations close to the ECRH radial deposition location at mid-radius, along with a reduction in phase velocity of large-scale density fluctuations. Measurements are compared with results from linear and non-linear flux-matched gyrokinetic (GK) simulations with the gyrokinetic code gene. Linear GK simulations show a reduction of phase velocity, indicating a pronounced change in the character of the dominant instability. Comparing measurement and non-linear GK simulation, as a central result, agreement is obtained in the shape of radial turbulence level profiles. However, the turbulence intensity is increasing with additional heating in the experiment, while gyrokinetic simulations show a decrease.

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Section: Introductionmentioning

confidence: 67%

Section: Introductionmentioning

confidence: 99%

Core turbulence behavior moving from ion-temperature-gradient regime towards trapped-electron-mode regime in the ASDEX Upgrade tokamak and comparison with gyrokinetic simulation

et al. 2015

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“…This choice of k-space spectrum is in agreement with nonlinear simulations and observations. 4,11 Fluxes computed by QuaLiKiz have been compared with GYRO non-linear simulations, and agreement for both heat and particle fluxes have been obtained in R=L T ; Z eff ; T i =T e , and collisionality scans around GA-standard case parameters. 4 Extensive GYRO non-linear simulations consisting of q-profile and magnetic shear scans have previously been carried out.…”

Section: Review Of the Qualikiz Modelmentioning

confidence: 99%

“…4,10 The model for the saturated electrostatic potential-a critical ingredient in evaluating the turbulent fluxes-consists of a mixing length rule weighted by a k-space spectral function validated against both non-linear simulations and experimental observations. 4,11 The saturated potential frequency spectral shape is taken as a Lorentzian, with a width equal to the linear growth rate. This assumption has been shown to agree with non-linear simulations and experimental observations at transport relevant wavelengths.…”

Section: Review Of the Qualikiz Modelmentioning

confidence: 99%

Quasilinear transport modelling at low magnetic shear

et al. 2012

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Accurate and computationally inexpensive transport models are vital for routine and robust predictions of tokamak turbulent transport. To this end, the QuaLiKiz [Bourdelle et al., Phys. Plasmas 14, 112501 (2007)] quasilinear gyrokinetic transport model has been recently developed. QuaLiKiz flux predictions have been validated by non-linear simulations over a wide range in parameter space. However, a discrepancy is found at low magnetic shear, where the quasilinear fluxes are significantly larger than the non-linear predictions. This discrepancy is found to stem from two distinct sources: the turbulence correlation length in the mixing length rule and an increase in the ratio between the quasilinear and non-linear transport weights, correlated with increased non-linear frequency broadening. Significantly closer agreement between the quasilinear and non-linear predictions is achieved through the development of an improved mixing length rule, whose assumptions are validated by non-linear simulations. V C 2012 American Institute of Physics.

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“…1 The nonlinear gyrokinetic model has been used extensively to study the turbulent transport in tokamak plasmas, with recent papers focusing on validation efforts that involve direct comparisons with measured turbulence. [2][3][4][5][6][7][8] Validation of the gyrokinetic model is an important step towards using this model for assessing the performance of fusion plasmas in the future.…”

Section: Introductionmentioning

confidence: 99%

Quantitative comparison of electron temperature fluctuations to nonlinear gyrokinetic simulations in C-Mod Ohmic L-mode discharges

et al. 2016

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Long wavelength turbulent electron temperature fluctuations (kyρs < 0.3) are measured in the outer core region (r/a > 0.8) of Ohmic L-mode plasmas at Alcator C-Mod [E. S. Marmar et al., Nucl. Fusion 49, 104014 (2009)] with a correlation electron cyclotron emission diagnostic. The relative amplitude and frequency spectrum of the fluctuations are compared quantitatively with nonlinear gyrokinetic simulations using the GYRO code [J. Candy and R. E. Waltz, J. Comput. Phys. 186, 545 (2003)] in two different confinement regimes: linear Ohmic confinement (LOC) regime and saturated Ohmic confinement (SOC) regime. When comparing experiment with nonlinear simulations, it is found that local, electrostatic ion-scale simulations (kyρs ≲ 1.7) performed at r/a ∼ 0.85 reproduce the experimental ion heat flux levels, electron temperature fluctuation levels, and frequency spectra within experimental error bars. In contrast, the electron heat flux is robustly under-predicted and cannot be recovered by using scans of the simulation inputs within error bars or by using global simulations. If both the ion heat flux and the measured temperature fluctuations are attributed predominantly to long-wavelength turbulence, then under-prediction of electron heat flux strongly suggests that electron scale turbulence is important for transport in C-Mod Ohmic L-mode discharges. In addition, no evidence is found from linear or nonlinear simulations for a clear transition from trapped electron mode to ion temperature gradient turbulence across the LOC/SOC transition, and also there is no evidence in these Ohmic L-mode plasmas of the “Transport Shortfall” [C. Holland et al., Phys. Plasmas 16, 052301 (2009)].

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Turbulence in the TORE SUPRA Tokamak: Measurements and Validation of Nonlinear Simulations

Cited by 74 publications

References 16 publications

Core turbulence behavior moving from ion-temperature-gradient regime towards trapped-electron-mode regime in the ASDEX Upgrade tokamak and comparison with gyrokinetic simulation

Core turbulence behavior moving from ion-temperature-gradient regime towards trapped-electron-mode regime in the ASDEX Upgrade tokamak and comparison with gyrokinetic simulation

Quasilinear transport modelling at low magnetic shear

Quantitative comparison of electron temperature fluctuations to nonlinear gyrokinetic simulations in C-Mod Ohmic L-mode discharges

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