Predictive turbulence-driven flux model of scrape-off layer widths across confinement regimes in tokamaks

In this contribution, a non-isothermal extension of the Sheared Spectra Filament model (SSF model) describing the impacts of magnetic shear and ExB shear on the cross-field turbulent transport in the scrape-off layer has been derived [1]. It relies on the description of the curvature drive of the interchange instability balanced by the parallel flow damping, the magnetic shear and the ExB shear. This turbulence-driven transport model results in predictions for the various decay lengths as a function of a set of scalar plasma and device parameters. The model predictions for the SOL decay lengths are validated through a comparison with a large database of L-mode and H-mode DIII-D discharges. Radial decay lengths for density, temperature and pressure profiles measured in the SOL with Thomson Scattering in DIII-D are well reproduced across L-mode and H-mode regimes. A scaling law for the heat flux decay length λ_q is then derived, leading to predictions in quantitative agreement with the multi-machine empirical Eich scaling in H-mode. Predictions for ITER with the SSF model show that λ_q≈2mm, which is 3-4 times higher than the Eich scaling.

[1] M. Peret et al., Physics of Plasmas 29, 072306 (2022)