Self-consistent simulation of transport and turbulence in tokamak edge plasma by coupling SOLPS-ITER and BOUT++

Zhang, D.R.; Chen, Y.P.; Xu, X. Q.; Xia, Tianyang

doi:10.1063/1.5084093

Cited by 20 publications

(23 citation statements)

References 19 publications

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“…One approach to remedy this deficiency in mean-field transport codes is to couple them to turbulence codes that can a) Electronic mail: reinart.coosemans@kuleuven.be b) Electronic mail: wouter.dekeyser@kuleuven.be c) Electronic mail: martine.baelmans@kuleuven.be then provide transport coefficients self-consistently. In such an approach, the turbulence code can either resolve the turbulence locally in distinct parts of the mean-field domain as performed by for example Nishimura et al 16 , or it can globally solve the entire mean-field computational domain as performed by Zhang et al 17 . Note that in the former approach non-local transport effects cannot be captured, while in the latter approach the computational cost is expected to remain a bottleneck due to the need for a 3D turbulence simulation resolving the relevant turbulent length and time scales.…”

Section: Introductionmentioning

confidence: 99%

Turbulent kinetic energy in 2D isothermal interchange-dominated scrape-off layer E × B drift turbulence: Governing equation and relation to particle transport

2021

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This paper studies the turbulent kinetic energy (k ⊥ ) in 2D isothermal electrostatic interchange-dominated ExB drift turbulence in the scrape-off layer, and its relation to particle transport. An evolution equation for the former is analytically derived from the underlying turbulence equations. Evaluating this equation shows that the dominant source for the turbulent kinetic energy is due to interchange drive, while the parallel current loss to the sheath constitutes the main sink. Perpendicular transport of the turbulent kinetic energy seems to play a minor role in the balance equation. Reynolds stress energy transfer also seems to be negligible, presumably because no significant shear flow develops under the given assumptions of isothermal sheath-limited conditions in the open field line region. The interchange source of the turbulence is analytically related to the average turbulent ExB energy flux, while a regression analysis of TOKAM2D data suggests a model that is linear in the turbulent kinetic energy for the sheath loss. A similar regression analysis yields a diffusive model for the average radial particle flux, in which the anomalous diffusion coefficient scales with the square root of the turbulent kinetic energy. Combining these three components, a closed set of equations for the mean-field particle transport is obtained, in which the source of the turbulence depends on mean flow gradients and k ⊥ through the particle flux, while the turbulence is saturated by parallel losses to the sheath. Implementation of this new model in a 1D mean-field code shows good agreement with the original TOKAM2D data over a range of model parameters.Recently, Bufferand et al. 19 proposed a mean-field model for the turbulent particle transport in the plasma edge that draws inspiration from these RANS models. More specifically, the model bears similarity to k(−ε) models, where equations for the turbulent kinetic energy k (and dissipation ε) are solved to provide time-and length scales to model the closure terms 18 . Bufferand et al. proposed a diffusive model for the radial particle transport where the anomalous trans-

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Section: Introductionmentioning

confidence: 99%

Turbulent kinetic energy in 2D isothermal interchange-dominated scrape-off layer E × B drift turbulence: Governing equation and relation to particle transport

2021

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“…Numerous SOL turbulence models and codes are now being extended to include these features. [92][93][94][95][96][97][98][99][100] The statistical framework with super-position of filaments can be used for analysis and interpretation of simulation results in these more advanced models, similar to what has been done here and previously for experimental measurements. As such, this work sets a new standard for validation of turbulence simulation codes.…”

Section: Discussionmentioning

confidence: 84%

Numerical turbulence simulations of intermittent fluctuations in the scrape-off layer of magnetized plasmas

Decristoforo,

Theodorsen,

Omotani

et al. 2021

Preprint

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Intermittent fluctuations in the boundary of magnetically confined plasmas are investigated by numerical turbulence simulations of a reduced fluid model describing the evolution of the plasma density and electric drift vorticity in the two-dimensional plane perpendicular to the magnetic field. Two different cases are considered, one describing resistive drift waves in the edge region and another including only the interchange instability due to unfavorable magnetic field curvature in the scrape-off layer. Analysis of long data time series obtained by single-point recordings are compared to predictions of a stochastic model describing the plasma fluctuations as a super-position of uncorrelated pulses. For both cases investigated, the radial particle density profile in the scrape-off layer is exponential with a radially constant scale length. The probability density function for the particle density fluctuations in the far scrape-off layer has an exponential tail. Radial motion of blob-like structures leads to large-amplitude bursts with an exponential distribution of peak amplitudes and the waiting times between them. The average burst shape is well described by a two-sided exponential function. The frequency power spectral density of the particle density is simply that of the average burst shape and is the same for all radial positions in the scrape-off layer. The fluctuation statistics obtained from the numerical simulations are in excellent agreement with recent experimental measurements on magnetically confined plasmas. The statistical framework defines a new validation metric for boundary turbulence simulations.

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“…Hydrogen ions are assumed, and input parameters are B 0 = 0.5 T, n 0 = 5 × 10 18 (10 19 ) m −3 , T e0 = 30 eV T i0 = 60 eV, T n0 = 10 eV, and L z = 40 (10) m, with changes to the high density parameters denoted by parentheses. The resolution is 16,16,16) for the low density case and 16,16,16) for the high density case. Both were run to an end time of…”

Section: B Benchmarks With Degas2mentioning

confidence: 99%

“…Ionization and charge exchange interactions are included. The neutral grid resolution is (N x , N y , N z , N v x , N v y , N v z ) = (16,32,32,6,6,6), with the same configuration space extents as the gyrokinetic species and velocity space extents v x,y,z ∈ [−4v t,i0 , 4v t,i0 ] defined in terms of the ion thermal speed. Piecewise-linear basis functions are also used for the numerical solution of the neutral distribution function.…”

Section: A Simulation Setupmentioning

confidence: 99%

“…Because of this, much neutral modeling has been carried out by kinetic Monte Carlo (MC) codes, [10][11][12] and these models have been coupled to fluid turbulence codes like TOKAM2D 13 and TOKAM3X. 14,15 SOLPS has been coupled to the six-field two-fluid turbulence code BOUT++ 16 , and the XGC framework incorporates a model of MC neutrals. [17][18][19][20] MC codes are subject to statistical noise, which can interfere with the accuracy and convergence of Eulerian codes 21 when coupled to them.…”

Section: Introductionmentioning

confidence: 99%

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Kinetic modeling of neutral transport for a continuum gyrokinetic code

Bernard,

Halpern,

Francisquez

et al. 2022

Preprint

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We present the first-of-its-kind coupling of a continuum full-f gyrokinetic turbulence model with a 6D continuum model for kinetic neutrals, carried out using the Gkeyll code.Our objective is to improve the first-principles understanding of the role of neutrals in plasma fueling, detachment, and their interaction with edge plasma profiles and turbulence statistics. Our model incorporates electron-impact ionization, charge exchange, and wall recycling. These features have been successfully verified with analytical predictions and benchmarked with the DEGAS2 Monte Carlo neutral code. We carry out simulations for a scrape-off layer (SOL) with simplified geometry and NSTX parameters. We compare these results to a baseline simulation without neutrals and find that neutral interactions reduce the normalized density fluctuation levels and associated skewness and kurtosis, while increasing auto-correlation times. A flatter density profile is also observed, similar to the SOL density shoulder formation in experimental scenarios with high fueling.

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Self-consistent simulation of transport and turbulence in tokamak edge plasma by coupling SOLPS-ITER and BOUT++

Cited by 20 publications

References 19 publications

Turbulent kinetic energy in 2D isothermal interchange-dominated scrape-off layer E × B drift turbulence: Governing equation and relation to particle transport

Turbulent kinetic energy in 2D isothermal interchange-dominated scrape-off layer E × B drift turbulence: Governing equation and relation to particle transport

Numerical turbulence simulations of intermittent fluctuations in the scrape-off layer of magnetized plasmas

Kinetic modeling of neutral transport for a continuum gyrokinetic code

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