Gyrokinetic study of turbulence suppression in a JET-ILW power scan

Doerk, H.; Challis, C.; Citrin, J.; García, J.; Görler, T.; Jenko, F.; Contributors, Jet

doi:10.1088/0741-3335/58/11/115005

Cited by 25 publications

(47 citation statements)

References 37 publications

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“…High transport levels of particles and heat for all species are found in the KBM/BAE regime, from which we deduce that this turbulence type must be stable or marginally stable. This situation is very similar to the analysis of several other plasmas with particularly good confinement properties, reaching from L-mode [12] to H-mode plasmas of the hybrid type at JET [8,13,14] and 3 He minority ICRH heated H-modes at ASDEX Upgrade [47,48]. The analysis of these cases indicates that optimal ITG stabilisation, and thus improved confinement is obtained by closely approaching the KBM/BAE limit from below (not surpassing it).…”

Section: Discussionsupporting

confidence: 79%

“…[9]), and in gyrokinetic modelling [10]. Comprehensive nonlinear gyrokinetic results are available since half a decade, reaching from virtually electrostatic low density DIII-D QH modes [11], to strongly electromagnetic JET L-modes [12] and Hmodes [8,13,14]. As shown in the course of this paper, the present ASDEX Upgrade non-inductive scenario is similar to the plasmas of the latter, strongly electromagnetic category.…”

Section: Introductionmentioning

confidence: 72%

“…Despite the electron profile being captured relatively well, TGLF predicts a/L T i ∼ 0.8, much lower than the experiment. This suggests nonlinear electromagnetic physics and fast ion effects to be responsible for the strong ion transport reduction as concluded in [12,27] for a JET L-mode plasma, as well as JET H-mode plasmas [8,13,14]. For the gyrokinetic analysis, we focus on the radial position ρ tor = 0.4, where a/L T i becomes large and starts to deviate from TGLF predictions.…”

Section: Experimental Parametersmentioning

confidence: 95%

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Turbulence in high-beta ASDEX upgrade advanced scenarios

et al. 2017

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Recent experiments at ASDEX Upgrade achieve non-inductive operation in full tungsten wall conditions by applying electron cyclotron and neutral beam current drive. These discharges are characterised by a well-measured safety factor profile, which does not drop below one, and a good energy confinement. By reproducing the experimental heat fluxes, nonlinear gyrokinetic simulations suggest that the observed strong peaking of the ion temperature in the core is caused by the stabilising impact of a significant beam ion content, as well as strong electromagnetic effects on turbulent transport. Quasilinear transport models are not yet applicable in this interesting and reactor relevant parameter regime, but available simulation data may serve as a testbed for improvements. As the present plasma is close to the kinetic ballooning (KBM) threshold, elevating the safety factor profile under otherwise identical conditions is proposed to clarify, whether profiles are ultimately limited by KBM turbulence, or by global stability constraints.

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Section: Discussionsupporting

confidence: 79%

Section: Introductionmentioning

confidence: 72%

Section: Experimental Parametersmentioning

confidence: 95%

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Turbulence in high-beta ASDEX upgrade advanced scenarios

et al. 2017

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“…This is expected: we did not include fast ions in the simulation, and furthermore QuaLiKiz is an electrostatic code and does not include nonlinearly enhanced electromagnetic stabilization of ITG in the saturation rule. Fast-ionenhanced electromagnetic stabilization of ITG turbulence is an important effect for high performance hybrid scenarios at inner radii [31,65,29,30,66]. Pertinently, nonlinear simulations have shown electromagnetic stabilization to be a critical effect in inner radii for this specific discharge [28].…”

Section: Jet Hybrid Scenario 75225mentioning

confidence: 98%

Tractable flux-driven temperature, density, and rotation profile evolution with the quasilinear gyrokinetic transport model QuaLiKiz

Citrin

Bourdelle

Casson

et al. 2017

Plasma Phys. Control. Fusion

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139

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Quasilinear turbulent transport models are a successful tool for prediction of core tokamak plasma profiles in many regimes. Their success hinges on the reproduction of local nonlinear gyrokinetic fluxes. We focus on significant progress in the quasilinear gyrokinetic transport model QuaLiKiz [C. Bourdelle et al. 2016 Plasma Phys. Control. Fusion 58 014036], which employs an approximated solution of the mode structures to significantly speed up computation time compared to full linear gyrokinetic solvers. Optimization of the dispersion relation solution algorithm within integrated modelling applications leads to flux calculations ×10 6−7 faster than local nonlinear simulations. This allows tractable simulation of flux-driven dynamic profile evolution including all transport channels: ion and electron heat, main particles, impurities, and momentum. Furthermore, QuaLiKiz now includes the impact of rotation and temperature anisotropy induced poloidal asymmetry on heavy impurity transport, important for W-transport applications. Application within the JETTO arXiv:1708.01224v2 [physics.plasm-ph] 7 Aug 2017Tractable flux-driven temperature, density, and rotation profile evolution with the quasilinear gyrokinetic tran integrated modelling code results in 1 s of JET plasma simulation within 10 hours using 10 CPUs. Simultaneous predictions of core density, temperature, and toroidal rotation profiles for both JET hybrid and baseline experiments are presented, covering both ion and electron turbulence scales. The simulations are successfully compared to measured profiles, with agreement mostly in the 5-25% range according to standard figures of merit. QuaLiKiz is now open source and available at www.qualikiz.com.Tractable flux-driven temperature, density, and rotation profile evolution with the quasilinear gyrokinetic tran

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“…Hence, the MFC effect is significant when the global magnetic shear is finite s ≈ 1 such as JET66404 with s ¼ 0.7, AUG29224 with s ¼ 1.08, and JET75225r064 with s ¼ 1.44. On the other hand, the MFC effect is weak, when the global magnetic shear is small s ≪ 1 such as the core plasma of JET hybrid discharge [30,32,33], for instance, JET75225r033 with s ¼ 0.16. This implies that low global magnetic shear is an important parameter for the electromagnetic stabilization [34][35][36].…”

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confidence: 99%

Persistence of Ion Temperature Gradient Turbulent Transport at Finite Normalized Pressure

et al. 2019

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Plasma β dependence of electromagnetic turbulent transport is investigated by means of gyrokinetic simulations with self-consistent change of the equilibrium magnetic field. It is found that energy transport due to ion-temperature-gradient (ITG) driven turbulence does not decrease with increasing β; that is, the ion energy diffusivity does not decrease, and the electron energy diffusivity increases with β. This is because magnetic fluctuations are significantly influenced by the background magnetic field structure change with β by the Pfirsch-Schluter current. The magnetic field change weakens the suppression effect of magnetic perturbations on the growth of the ITG mode, and it also suppresses nonlinear zonal flow production. The influence of the magnetic field change is significant as the global magnetic shear increases.

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Gyrokinetic study of turbulence suppression in a JET-ILW power scan

Abstract: IPB y98 2 0.7 τ ∼ − [5]. Detailed studies exist for high-power C-wall 'hybrid' plasmas at JET, where high Plasma Physics and Controlled Fusion

Cited by 25 publications

References 37 publications

Turbulence in high-beta ASDEX upgrade advanced scenarios

Turbulence in high-beta ASDEX upgrade advanced scenarios

Tractable flux-driven temperature, density, and rotation profile evolution with the quasilinear gyrokinetic transport model QuaLiKiz

Persistence of Ion Temperature Gradient Turbulent Transport at Finite Normalized Pressure

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