Theory-based scaling laws of near and far scrape-off layer widths in single-null L-mode discharges

Abstract

Theory-based scaling laws of the near and far scrape-off layer (SOL) widths are analytically derived for L-mode diverted tokamak discharges by using a two-fluid model. The near SOL pressure and density decay lengths are obtained by leveraging a balance among the power source, perpendicular turbulent transport across the separatrix, and parallel losses at the vessel wall, while the far SOL pressure and density decay lengths are derived by using a model of intermittent transport mediated by filaments. The analytical estimates of the pressure decay length in the near SOL is then compared to the results of three-dimensional, flux-driven, global, two-fluid turbulence simulations of L-mode diverted tokamak plasmas, and validated against experimental measurements taken from an experimental multi-machine database of divertor heat flux profiles, showing in both cases a very good agreement. Analogously, the theoretical scaling law for the pressure decay length in the far SOL is compared to simulation results and to experimental measurements in TCV L-mode discharges, pointing out the need of a large multi-machine database for the far SOL decay lengths.

Nucl. Fusion 2021

References in corpus (6)

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• On the role of filaments in perpendicular heat transport at the Scrape-off Layer
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• Effect of triangularity on plasma turbulence and the SOL-width scaling in L-mode diverted tokamak configurations
• Turbulent transport regimes in the tokamak boundary and operational limits
• Global fluid simulation of plasma turbulence in a stellarator with an island divertor
• Magnetic flutter effect on validated edge turbulence simulations
• Simulations of scrape-off layer power width for EAST H-mode plasma and ITER 15 MA baseline scenario by 2D electrostatic turbulence code
• Three-dimensional boundary turbulence simulations of a RFX-mod plasma in the presence of voltage biasing