Latest developments in BOUT++ boundary plasma turbulent transport simulations

A significant progress has been made recently in BOUT++ simulations. The results will be summarized here including, but not limited to: (1) Developed simulation models for density limited disruptions and the resulting scrape-of-layer broadening. (2) Derived a Landau fluid closure for arbitrary frequency, implemented and tested in BOUT++ simulations. (3) Performed linear analyses of peeling-ballooning modes in high beta pedestal plasmas. Taking the kinetic effects into account, simulations of kinetic peeling-ballooning mode show the existence of the high beta peeling-ballooning mode stability region. (4) Simulated the ELMs triggering by lithium pellet and its ablation process. Both BOUT++ turbulence and transport codes are used to simulate the divertor heat flux width, which is consistent with experimental Eich scaling for current tokamaks. However, transport simulations show that (1) Drifts and turbulence are locked in a tight competition for C-Mod and a critical SOL transport coefficient is found. (2) ITER & CFETR will possibly operate in a turbulence dominant regime with a heat flux width larger than those extrapolated from the Eich scaling and Goldston HD model sets the lower limit of the width.