Inference of main ion particle transport coefficients with experimentally constrained neutral ionization during edge localized mode recovery on DIII-D

Rosenthal, Aaron; Hughes, J.W.; Laggner, F. M.; Odstrčil, T.; Bortolon, A.; Wilks, Theresa; Sciortino, Francesco

doi:10.1088/1741-4326/acb95a

Cited by 9 publications

(17 citation statements)

References 61 publications

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“…The small modulation in both temperature and density likely contributes to the large errorbars reported in the D and v profiles. Finally, there are no un-physical or 'surprising' features in the inferred amplitude and phase behavior shown in figure 4 which have indicated changing transport coefficients in other studies [8,29,54]; therefore, time-independent transport coefficients seem sufficient to explain the experimental behavior.…”

Section: Discussionmentioning

confidence: 71%

“…Both the analytic and IMPRAD approach do not account for poloidal asymmetries in the density or source. In particular, the source is expected to have a significant poloidal asymmetry as observed on previous shots [8] and suggested in simulation of other shots on DIII-D [47][48][49]. In this discharge, only the LFS LLAMA source is utilized for transport inference as the modulation is clearer than the HFS and more investigation is required to determine how to provide a poloidal average of the two views.…”

Section: Discussionmentioning

confidence: 79%

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Pedestal main ion particle transport inference through gas puff modulation with experimental source measurements

Rosenthal,

Hughes,

Laggner

et al. 2024

Nucl. Fusion

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Transport in the DIII-D high confinement mode (H-mode) pedestal is investigated through a periodic edge gas puff modulation (GPM) which perturbs the deuterium density and source profiles. By using absolutely calibrated experimental edge ionization profile measurements, radial profiles of diffusion (D) and convection (v) are calculated into the pedestal region without depending on modeling the edge ionization source. An analytic approach with closed-form expressions for the D and v profiles and a more advanced Bayesian approach show evidence of an inward particle convection on the order of 1 m s−1 extending to normalized poloidal flux (ΨN) of 0.98. Meanwhile, diffusion reaches a minimum value of (0.03 ± 0.02) m2 s−1 in the pedestal region. Notably, the Bayesian approach, which utilizes the Aurora 1.5 D forward model inside the IMPRAD OMFIT module, provides radially resolved transport profiles withassociated uncertainty without requiring an explicit form for the perturbation to the density profile or source. The combination of  experimental ionization measurements and Bayesian inference provides an enhanced robust framework for investigating edgeparticle transport coefficients to experimentally test transport physics in order to improve predictive capabilities in the tokamak edge.

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Section: Discussionmentioning

confidence: 71%

Section: Discussionmentioning

confidence: 79%

Pedestal main ion particle transport inference through gas puff modulation with experimental source measurements

Rosenthal,

Hughes,

Laggner

et al. 2024

Nucl. Fusion

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“…The chosen radial behaviors capture the basic physics: the absolute turbulent fluctuations typically decay with increasing radius near the LCFS [8,[30][31][32][33] and neutral particles grow in abundance toward the wall [35,36]. The assumed radial decay of the turbulence also allows for direct comparison with section 2 and previous works [6,8].…”

Section: Intrinsic Rotation With Simple Profilesmentioning

confidence: 99%

Intrinsic rotation modulation by diffusive neutral particles in tokamaks

Brzozowski III,

Stoltzfus-Dueck

2024

Plasma Phys. Control. Fusion

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The modulated transport model, a model kinetic ion transport equation for the pedestal and scrape-off layer, is generalized to self-consistently include effects of a single neutral particle species. The neutrals contribute additional transport terms, modifying the v||-dependent orbit-averaged ion diffusivities of the original work and the resulting predicted intrinsic rotation of the ions. After making simplifying assumptions of the neutral transport, in particular taking the continuous transport limit via a short charge-exchange step expansion, we derive relatively simple analytic expressions that capture the diffusive neutral physics. Within the scope of the model's validity, the neutral-driven intrinsic rotation can compete with the turbulence-driven intrinsic rotation. However, for physically motivated parameters, the neutral-driven intrinsic rotation appears negligible, either on a term-by-term basis or due to a strong cancellation between the neutral-driven momentum diffusion and pinch terms. It appears that a treatment containing finite charge-exchange steps is necessary to capture neutral transport of strong flow momentum into the confined region from the scrape-off layer.

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“…Dynamic plasma states offer additional insights into the transport behavior compared to the steady state. This is true for heat transport [3,4], where transient states show how transport changes with altered conditions, but also, and especially, for particle transport [5][6][7][8][9][10][11][12][13], where convective and diffusive transport contributions can, in principle, be separated.…”

Section: Introductionmentioning

confidence: 99%

“…Figure13. Relative amplitude ((a), (c), (e)) and phase delays ((b), (d), (f )) for all discussed cases.…”

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confidence: 99%

Dynamic edge transport investigations at ASDEX Upgrade using gas puff modulation

et al. 2023

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Gas puff modulation experiments are performed at ASDEX Upgrade in L-mode,EDA H-mode and QCE discharges. Plasma density and temperatures are measuredand their temporal development is analyzed simultaneously, revealing that both heatand particle transport are strongly influenced by the modulation. As a consequence,the particle transport coefficients are underdetermined. In the transport modelling,the pedestal cannot be treated as a single region, but the pedestal foot must be allowedto increase its transport with gas puff modulation independently. The analysis of thetemporal behaviours of the heat and particle diffusivities shows that they are stronglycorrelated. Considering the heat diffusivity as a a proxy for the particle diffusivity,allows interpretation of the density evolution: a pinch is not required for any ofthe discharges. An analysis with the gyrokinetic turbulence code GENE identifiesdominant instabilities and reproduces several experimentally found trends. Despite alluncertainties concerning particle transport, one can expect a future reactor featuringa weak edge density gradient even with purely diffusive transport.

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Inference of main ion particle transport coefficients with experimentally constrained neutral ionization during edge localized mode recovery on DIII-D

Cited by 9 publications

References 61 publications

Pedestal main ion particle transport inference through gas puff modulation with experimental source measurements

Pedestal main ion particle transport inference through gas puff modulation with experimental source measurements

Intrinsic rotation modulation by diffusive neutral particles in tokamaks

Dynamic edge transport investigations at ASDEX Upgrade using gas puff modulation

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