Dependence of high-Z redeposition on the field-to-surface pitch angle and other sheath parameters in tokamaks

Accurately predicting redeposition is vital for high-Z plasma-facing component (PFC) survivability in magnetic confinement fusion. In this study, we categorize high-Z redeposition into three mechanisms: geometric-driven (prompt), sheath-driven (local), and scrape-off-layer-driven (far) redeposition....

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Bibliographic Details
Published in:Physics of plasmas 2024-05, Vol.31 (5)
Main Authors: Easley, D. C., Diaw, A., Younkin, T. R., Donovan, D. C., Unterberg, E. A., Nichols, J. H., Johnson, C. A., Kumar, A.
Format: Article
Language:English
Subjects:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
magnetic confinement fusion
Parameters
Pitch (inclination)
plasma facing components
plasma impurities
plasma material interactions
plasma sheaths
Sheaths
Survivability
Tokamak devices
tokamaks
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Summary:Accurately predicting redeposition is vital for high-Z plasma-facing component (PFC) survivability in magnetic confinement fusion. In this study, we categorize high-Z redeposition into three mechanisms: geometric-driven (prompt), sheath-driven (local), and scrape-off-layer-driven (far) redeposition. To investigate these mechanisms, we employ Monte Carlo transport codes to simulate azimuthally symmetric tungsten source erosion and redeposition in a tokamak. By iteratively analyzing critical parameters, we evaluate redeposition scaling for each mechanism. Specifically, we investigate the impact of magnetic-field-to-PFC pitch angle assumptions on PFC losses into the scrape-off layer. Our findings reveal significant pitch angle sensitivity due to an asymmetric prompt vs local redeposition trade-off. These results enhance our understanding of redeposition phenomena in fusion plasma environments.
ISSN:1070-664X
1089-7674
DOI:10.1063/5.0187331