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  4. Estimating cross-field particle transport at the outer midplane of TCV by tracking filaments with machine learning
 
research article

Estimating cross-field particle transport at the outer midplane of TCV by tracking filaments with machine learning

Han, W.
•
Offeddu, N.  
•
Golfinopoulos, T.
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July 1, 2023
Nuclear Fusion

Cross-field transport of particles in the boundary region of magnetically confined fusion plasmas is dominated by turbulence. Blobs, intermittent turbulent structures with large amplitude and a filamentary shape appearing in the scrape-off layer (SOL), are known from theoretical and experimental studies to be the main contributor to the cross-field particle transport. The dynamics of blobs differs depending on various plasma conditions, including triangularity (d). In this work, we analyze triangularity dependence of the cross-field particle transport at the outer midplane of plasmas with d = +0.38, +0.15, -0.14, and -0.26 on the Tokamak a` Configuration Variable, using our novel machine learning (ML) blob-tracking approach applied to gas puff imaging data. The cross-field particle flux determined in this way is of the same order as the overall transport inferred from KN1D, GBS, and SOLPS-ITER simulations, suggesting that the blobs identified by the ML blob-tracking account for most of the cross-field particle transport in the SOL. Also, the ML blob-tracking and KN1D show a decrease in the cross-field particle transport as d becomes more negative. The blob-by-blob analysis of the result from the tracking reveals that the decrease of cross-field particle transport with decreasing d is accompanied by a decrease in the number of blobs in a fixed time, which tend to have larger area and lower radial speed. Also, the blobs in these plasmas are in the connected sheath regime, and show a velocity scaling consistent with the two-region model.

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Type
research article
DOI
10.1088/1741-4326/acdae5
Web of Science ID

WOS:001005653100001

Author(s)
Han, W.
Offeddu, N.  
Golfinopoulos, T.
Theiler, C.  
Terry, J. L.
Wuthrich, C.  
Galassi, D.  
Colandrea, C.  
Marmar, E. S.
Date Issued

2023-07-01

Publisher

IOP Publishing Ltd

Published in
Nuclear Fusion
Volume

63

Issue

7

Article Number

076025

Subjects

Physics, Fluids & Plasmas

•

Physics

•

negative triangularity

•

edge/sol turbulence

•

machine learning

•

gas puff imaging

•

particle transport

•

tokamak

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scrape-off-layer

•

edge

•

turbulence

Editorial or Peer reviewed

REVIEWED

Written at

EPFL

EPFL units
SPC  
Available on Infoscience
July 3, 2023
Use this identifier to reference this record
https://infoscience.epfl.ch/handle/20.500.14299/198660
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