Estimating the error in filament propagation measurement using a synthetic probe

Shanahan, B.; Killer, C.; Pechstein, G.; Henneberg, S. A.; Fuchert, G.; Grulke, O.

doi:10.1088/1361-6587/ac2ff7

Cited by 4 publications

(5 citation statements)

References 34 publications

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“…This experimental comparison in turn inspired the work in Reference [39], where the sources of error in the filament characteristics via probe measurement in the Wendelstein 7-X SOL were quantified. The primary source of error was the one dimensional, conditionally-averaged measurement which systematically underestimated the filament size.…”

Section: Experimental Comparisonmentioning

confidence: 66%

“…Filaments were randomly seeded with a diameter and pressure within experimental parameters, and their resultant trajectories were measured using the synthetic diagnostic. The synthetic scaling is reproduced in Figure 4 [39], where the solid green circles indicate the filament properties measured by the synthetic diagnostic, and the hollow green circles indicate the actual properties determined from simulation. The green bar which connects these dots, then, indicates the total error associated with probe measurements.…”

Section: Experimental Comparisonmentioning

confidence: 99%

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Filament simulations for stellarators; a review of recent progress

Shanahan

2024

Front. Phys.

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A review of recent advances in simulations of turbulent filaments with relevance to stellarators is presented. Progress in performing global edge turbulence simulations is discussed as well as results from seeded filament simulations with applications to the unique environment of a stellarator island divertor–including abrupt changes in connection length and highly-nonuniform curvature drive. It is determined that the motion of filaments generally follows the average curvature, but strong nonuniform perturbations can shear a filament and reduce the overall transport. The coherence of filament transport is also determined to be influenced by the collisionality and electron plasma beta. By simplifying the simulation geometries, large parameter scans can be performed which accurately reflect the macroscopic transport of filaments observed in Wendelstein 7-X. Comparisons to experiments are discussed, and a the develeopment of a synthetic diagnostic has been able to inform experimental measurements by quantifying potential sources of error in filament propagation measurements. A discussion of the necessary extension to more complex multifluid models, and the scope for near-term filament simulations in stellarators, is provided.

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Section: Experimental Comparisonmentioning

confidence: 66%

Section: Experimental Comparisonmentioning

confidence: 99%

Filament simulations for stellarators; a review of recent progress

Shanahan

2024

Front. Phys.

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“…Such probes are used in the scrape-off layer of magnetic confinement fusion plasmas to measure flows relevant to particle and power exhaust. The specific case reported were filaments measured on W7-X [52]. Those were compared with drift-plane simulations.…”

Section: Synthetic Diagnostics Integration Verification and Validatio...mentioning

confidence: 99%

Summary report of the 4th IAEA Technical Meeting on Fusion Data Processing, Validation and Analysis (FDPVA)

Vicente

Mazon

et al. 2023

Nucl. Fusion

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The objective of the fourth Technical Meeting on Fusion Data Processing, Validation and Analysis was to provide a platform during which a set of topics relevant to fusion data processing, validation and analysis are discussed with the view of extrapolating needs to next step fusion devices such as ITER. The validation and analysis of experimental data obtained from diagnostics used to characterize fusion plasmas are crucial for a knowledge-based understanding of the physical processes governing the dynamics of these plasmas. This paper presents the recent progress and achievements in the domain of plasma diagnostics and synthetic diagnostics data analysis (including image processing, regression analysis, inverse problems, deep learning, machine learning, big data and physics-based models for control) reported at the meeting. The progress in these areas highlight trends observed in current major fusion confinement devices. A special focus is dedicated on data analysis requirements for ITER and DEMO with a particular attention paid to Artificial Intelligence for automatization and improving reliability of control processes.

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“…As such, turbulence simulations in stellarators have focused on the core transport using either a gyrokinetic (Xanthopoulos et al 2007;Bañón Navarro et al 2020;Maurer et al 2020;Singh et al 2022) or, less commonly, a fluid approach (Kleiber & Scott 2005). Recent work using local fluid simulations has informed interpretation of experimental measurements (Shanahan, Dudson & Hill 2018;Killer et al 2020;Shanahan et al 2021;Huslage et al 2023), without requiring modelling of the complex and numerically challenging SOL topology. Developments of numerical methods have provided the opportunity for global fluid turbulence simulations in stellarator geometries (Shanahan, Dudson & Hill 2019;Coelho et al 2022), but a general understanding of global phenomena at the edge and SOL of stellarators is only in its infancy.…”

Section: Introductionmentioning

confidence: 99%

“…2020; Shanahan et al. 2021; Huslage et al. 2023), without requiring modelling of the complex and numerically challenging SOL topology.…”

Section: Introductionmentioning

confidence: 99%

Global fluid turbulence simulations in the scrape-off layer of a stellarator island divertor

Shanahan,

Bold,

Dudson

2024

J. Plasma Phys.

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Isothermal fluid turbulence simulations have been performed in the edge and scrape-off layer (SOL) of an analytic stellarator configuration with an island divertor, thereby providing numerical insight into edge turbulence in regions around islands in a stellarator. The steady-state transport follows the a curvature drive that is inverse to the major radius ( $1/R$ ) toward the outboard side, but large fluctuations are present throughout the island divertor region, with the average wavelength of similar size to the island width. The system exhibits a prominent $m=2$ , $n=5$ mode, where m is the poloidal mode number and n is the toroidal mode number, although other modes are present. The amplitude and radial extent of the density fluctuations are similar throughout the edge and SOL, but can decrease near island O-points. The fluctuations exhibit a predominantly positive skewness on the outboard midplane, indicating blob-like perturbations for the transport into the outer SOL. It is determined that a point on the separatrix is generally more correlated with regions outside of the SOL than a nearby reference point which does not lie on the separatrix.

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Estimating the error in filament propagation measurement using a synthetic probe

Cited by 4 publications

References 34 publications

Filament simulations for stellarators; a review of recent progress

Filament simulations for stellarators; a review of recent progress

Summary report of the 4th IAEA Technical Meeting on Fusion Data Processing, Validation and Analysis (FDPVA)

Global fluid turbulence simulations in the scrape-off layer of a stellarator island divertor

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