Testing neoclassical and turbulent effects on poloidal rotation in the core of DIII-D

Chrystal, C.; Burrell, K.H.; Grierson, B. A.; Staebler, G. M.; Solomon, W. M.; Wang, W. X.; Rhodes, T. L.; Schmitz, L.; Kinsey, J. E.; Lao, L. L.; deGrassie, J.S.; Mordijck, S.; Meneghini, O.

doi:10.1063/1.4887296

Cited by 13 publications

(16 citation statements)

References 39 publications

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“…Well-established neoclassical models [10][11][12][13] have been used to calculate the poloidal rotation velocity. Based on these, a significant deviation of poloidal rotation from the neoclassical prediction was observed in previous studies on many toka maks [14][15][16][17].…”

Section: Introductionsupporting

confidence: 60%

Studies of Reynolds stress and the turbulent generation of edge poloidal flows on the HL-2A tokamak

Long¹,

Diamond²,

Xu³

et al. 2019

Nucl. Fusion

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Several new results in the physics of edge poloidal flows, turbulent stresses and momentum transport are reported. These are based on experiments on the HL-2A tokamak. Significant deviation from neoclassical prediction for mean poloidal flow in Ohmic and L mode discharges is deduced from direct measurements of the turbulent Reynolds stress. The deviation increases with heating power. The turbulent poloidal viscosity is synthesized from fluctuation data, and is found to be comparable to the turbulent particle diffusivity. The intrinsic poloidal torque is deduced from synthesis, for the first time. PDFs of particle flux and Reynolds stress are obtained. Both exhibit fat tails and large kurtosis, suggesting that the momentum transport process represented by the Reynolds stress is not well described by quasilinear calculations.

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Section: Introductionsupporting

confidence: 60%

Studies of Reynolds stress and the turbulent generation of edge poloidal flows on the HL-2A tokamak

Long¹,

Diamond²,

Xu³

et al. 2019

Nucl. Fusion

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“…The project is very active, with an average of over 100 commits per month and a monthly stable release cycle. To date OMFIT has fostered the research leading to the following refereed journal publications [18,[22][23][24][25][26][27].…”

Section: A Bottom-up Strategy To Integrated Modelingmentioning

confidence: 99%

“…This OMFIT workflow has streamlined the way DIII-D kinetic equilibrium reconstruction is carried out, and the resulting equilibria have been the starting point for numerous and diverse experimental analyses. The power, particle and momentum-balance information naturally output as part of the transport code calculation provides the basis for experimental transport analyses and validation of transport models [23,57,58].…”

Section: Kinetic Equilibrium Reconstructionmentioning

confidence: 99%

Integrated modeling applications for tokamak experiments with OMFIT

et al. 2015

Self Cite

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One modeling framework for integrated tasks (OMFIT) is a comprehensive integrated modeling framework which has been developed to enable physics codes to interact in complicated workflows, and support scientists at all stages of the modeling cycle. The OMFIT development follows a unique bottom-up approach, where the framework design and capabilities organically evolve to support progressive integration of the components that are required to accomplish physics goals of increasing complexity. OMFIT provides a workflow for easily generating full kinetic equilibrium reconstructions that are constrained by magnetic and motional Stark effect measurements, and kinetic profile information that includes fast-ion pressure modeled by a transport code. It was found that magnetic measurements can be used to quantify the amount of anomalous fast-ion diffusion that is present in DIII-D discharges, and provide an estimate that is consistent with what would be needed for transport simulations to match the measured neutron rates. OMFIT was used to streamline edge-stability analyses, and evaluate the effect of resonant magnetic perturbation (RMP) on the pedestal stability, which have been found to be consistent with the experimental observations. The development of a five-dimensional numerical fluid model for estimating the effects of the interaction between magnetohydrodynamic (MHD) and microturbulence, and its systematic verification against analytic models was also supported by the framework. OMFIT was used for optimizing an innovative high-harmonic fast wave system proposed for DIII-D. For a parallel refractive index > ∥ n 3, the conditions for strong electron-Landau damping were found to be independent of launched ∥ n and poloidal angle. OMFIT has been the platform of choice for developing a neural-network based approach to efficiently perform a non-linear multivariate regression of local transport fluxes as a function of local dimensionless parameters. Transport predictions for thousands of DIII-D discharges showed excellent agreement with the power balance calculations across the whole plasma radius and over a broad range of operating Nuclear Fusion

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“…the measurements do not overlay as a function of ρ tor , the HFS T i and u tor profiles are shifted accordingly in order to avoid equilibrium effects on the reconstruction of u pol . This method has been introduced in [40] and the applied shifts are within the uncertainty of the pickup coil measurements [28]. Additionally, possible atomic physics effects are carefully treated for the reconstruction of the core poloidal rotation.…”

Section: Measurement Techniquementioning

confidence: 99%

Measurement of the complete core plasma flow across the LOC–SOC transition at ASDEX Upgrade

et al. 2017

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A newly installed core charge exchange recombination spectroscopy (CXRS) diagnostic at ASDEX Upgrade (AUG) enables the evaluation of the core poloidal rotation (u pol) through the inboard-outboard asymmetry of the toroidal rotation with an accuracy of 0.5 to 1 km/s. Using this technique, the total plasma flow has been measured in Ohmic L-mode plasmas across the transition from the linear to saturated ohmic confinement (LOC-SOC) regimes. The core poloidal rotation of the plasma around mid-radius is found to be always in the ion diamagnetic direction, in disagreement with neoclassical (NC) predictions. The edge rotation is found to be electron-directed and consistent with NC codes. This measurement provides as well the missing ingredient to evaluate the core E × B velocity (u E× B) from data only, which can then be compared to measurements of the perpendicular velocity of the turbulent fluctuations (u ⊥) to gain information on the turbulent phase velocity (v ph). The non neoclassical u pol from CXRS leads to good agreement between u E× B and u ⊥ indicating that v ph is small and at similar values as found with gyrokinetic simulations. Moreover, the data shows a shift of v ph in the ion-diamagnetic direction at the edge after the transition from LOC to SOC consistent with a change in the dominant turbulence regime. The upgrade of the core CXRS system provides as well a deeper insight into the intrinsic rotation. This paper shows that the reversal of the core toroidal rotation occurs clearly after the LOC-SOC transition and concomitant with the peaking of the electron density.

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Testing neoclassical and turbulent effects on poloidal rotation in the core of DIII-D

Cited by 13 publications

References 39 publications

Studies of Reynolds stress and the turbulent generation of edge poloidal flows on the HL-2A tokamak

Studies of Reynolds stress and the turbulent generation of edge poloidal flows on the HL-2A tokamak

Integrated modeling applications for tokamak experiments with OMFIT

Measurement of the complete core plasma flow across the LOC–SOC transition at ASDEX Upgrade

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