This tutorial-style presentation will begin with a brief review of basic sheath physics and thesheath boundary conditions for low frequency turbulence simulations. A few consequences ofsheaths for scrape-off layer (SOL) instabilities will then be discussed using analytical models toprovide insight. Using a scaling correspondence between linear instabilities and turbulentstructures, semi-quantitative sheath-related propagation regimes of blob-filaments will bediscussed and compared with experimental measurements. Turning to RF sheaths, afterreviewing the physics of RF rectification, thermal sheath boundary conditions are generalized todescribe the effect of RF-driven sheaths on low frequency turbulence. ICRF-driven sheathstypically have much higher sheath potentials than their thermal sheath counterparts. Recentwork using the Hermes turbulence code to model ICRF driven convection and changes in theSOL density profile will be summarized. In this work the importance of 3D geometry for themodeling is emphasized. Convective cells near an antenna are shown to influence the transportof impurity ions that originate from RF-induced sputtering. Finally, some comments,speculations and challenges for modeling grazing magnetic angle sheaths will be presented.
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