SOLT3D modeling of plasma instabilities and turbulence in tokamak scrape-off layer and divertor *

SOLT3D is a plasma model for tokamak scrape-off layer and divertor, implemented in the BOUT++ framework [1]. The model supports basic fluid instabilities relevant to scrape-off layer (SOL) and divertor plasmas: the drift-resistive-ballooning mode instability driven by the magnetic curvature and the radial gradient of plasma pressure, and the conducting-wall mode instability driven by the end-plate sheath boundary conditions and the radial gradient of plasma temperature. SOLT3D has been benchmarked against analytic linear dispersion relations and against some known nonlinear results, demonstrating excellent agreement. The model is used to develop some new insights on linear plasma instabilities in the tokamak edge, in particular in the low-fields side (LFS) and high-field side (HFS). For nonlinear regimes, SOLT3D is used to assess the role of different drive mechanisms for fluid plasma turbulence for parameters relevant to tokamak SOL and divertor. [1] B. D. Dudson et al. Comput. Phys. Commun. 180, 1467–1480 (2009).