Nonlinear turbulent transport in magnetic fusion plasmas

In this paper, the influence of the parallel nonlinearity on zonal flows and heat transport in global particle-in-cell ion-temperature-gradient simulations is studied. Although this term is in theory orders of magnitude smaller than the others, several authors ͓L. In particular, it is demonstrated that the parallel nonlinearity, while important for energy conservation, affects the zonal electric field only if the simulation is noise dominated. When a proper convergence is reached, the influence of parallel nonlinearity on the zonal electric field, if any, is shown to be small for both the cases of decaying and driven turbulence.

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“…The absence of any temperature gradient evolution result in Ref. 29 makes a more detailed comparison with our simulations impossible.…”

Section: -5mentioning

confidence: 81%

“…29 the question of the influence of parallel nonlinearity has been examined. However, those simulations had no sources and used a number of particles per mode of about 20, which is, according to the results presented here, well short of what is necessary.…”

Section: -5mentioning

confidence: 99%

Influence of the parallel nonlinearity on zonal flows and heat transport in global gyrokinetic particle-in-cell simulations

et al. 2009

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“…The code with the key additional domain decomposition in radial dimension is named as GTC-P. The original version of GTC-P has demonstrated unprecedented efficiency for turbulent transport scaling analysis spanning the range from present generation experiments to the large ITER-scale plasmas [1,4,14]. However, earlier investigations [4] only explored flat MPI programming and suffered from load imbalance issues at high processor counts.…”

Section: Introductionmentioning

confidence: 99%

Kinetic turbulence simulations at extreme scale on leadership-class systems

Wang

Ethier

Tang

et al. 2013

Proceedings of the International Conference on High Performance Computing, Networking, Storage and Analysis

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Reliable predictive simulation capability addressing confinement properties in magnetically confined fusion plasmas is critically-important for ITER, a 20 billion dollar international burning plasma device under construction in France. The complex study of kinetic turbulence, which can severely limit the energy confinement and impact the economic viability of fusion systems, requires simulations at extreme scale for such an unprecedented device size. Our newly optimized, global, ab initio particle-in-cell code solving the nonlinear equations underlying gyrokinetic theory achieves excellent performance with respect to "time to solution" at the full capacity of the IBM Blue Gene/Q on 786,432 cores of Mira at ALCF and recently of the 1,572,864 cores of Sequoia at LLNL. Recent multithreading and domain decomposition optimizations in the new GTC-P code represent critically important software advances for modern, low memory per core systems by enabling routine simulations at unprecedented size (130 million grid points ITER-scale) and resolution (65 billion particles).

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“…Specifically, they argued for the presence of higher order terms in φ in the gyrokinetic Poisson's equation due to the fact that the 2 background distribution is Maxwellian only to the lowest order. In view of the recent highly interesting investigations based on the original gyrokinetic Vlasov-Poisson equations (using the linear φ) for studying the nonlinear interactions between microturbulence and the long wavelength zonal flow modes [10][11][12], we will re-examine these equations in the present paper from the point of view of the drift kinetic approximation of the original Vlasov-Poisson system and the associated guiding center dynamics. Starting from a simple procedure as described in Ref.…”

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confidence: 99%

“…The results confirm that the commonly used gyrokinetic Vlasov-Poisson equations are valid for an arbitrary distribution function in the long wavelength limit. In a recent paper [12], the nonlinearly-generated long wavelength (global) zonal flows due to ITG drift turbulence has been reported. It is shown that, by using the GTC code [18] for global gyrokinetic PIC simulation, that the damping of these long wavelength modes by the velocity space nonlinearity in the form of E ∂δf /∂v , from the last term in Eq.…”

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confidence: 99%

On Higher-order Corrections to Gyrokinetic Vlasov-Poisson Equations in the Long Wavelength Limit

Kolesnikov¹

2009

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In this paper, a simple iterative procedure is presented for obtaining the higher order E×B and dE/dt (polarization) drifts associated with the gyrokinetic Vlasov-Poisson equations in the long wavelength limit ofL is the scale length of the background inhomogeneity and is a smallness parameter. It can be shown that these new higher order k ⊥ ρ i terms, which are also related to the higher order Since the first derivations of the gyrokinetic Vlasov-Poisson equations [1, 2], tremendous progress has been made over the years in formulating and understanding these equations [3][4][5][6][7][8] for use in magnetic fusion research. They have also become the basis for the many simulation codes for turbulence and neoclassical transport studies in the community. In the electrostatic limit, this set of nonlinear equations keeps only the linear response of the perturbed potential φ and conserves energy to the order of φ 2 . It has been pointed out by a recent paper [9] that this version of the gyrokinetic Poisson's equation (also known as the gyrokinetic quasineutralilty condition)based on the linear φ may not be adequate for long wavelength modes, which, in turn, limits its application in describing correct physics on transport time scales. Specifically, they argued for the presence of higher order terms in φ in the gyrokinetic Poisson's equation due to the fact that the 2 background distribution is Maxwellian only to the lowest order. In view of the recent highly inter-

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Nonlinear turbulent transport in magnetic fusion plasmas

Cited by 9 publications

References 46 publications

Influence of the parallel nonlinearity on zonal flows and heat transport in global gyrokinetic particle-in-cell simulations

Influence of the parallel nonlinearity on zonal flows and heat transport in global gyrokinetic particle-in-cell simulations

Kinetic turbulence simulations at extreme scale on leadership-class systems

On Higher-order Corrections to Gyrokinetic Vlasov-Poisson Equations in the Long Wavelength Limit

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