Thermal dynamics in the flux-coordinate independent turbulence code GRILLIX

GRILLIX employs the flux-coordinate independent approach (FCI), which allows us to study boundary plasma turbulence in realistic diverted configurations. Recently, the physical model in GRILLIX has been extended to a global drift-reduced Braginskii model, without any separation between background and fluctuations. It includes electromagnetic and thermal dynamics with hot ions, relaxation of the Boussinesq approximation and non-linear parametric dependencies. This contribution presents solutions to associated issues, that is, the ion diamagnetic polarization and the stiff parallel heat conduction. Simulations based on parameters characteristic for the Alcator C-Mod tokamak were carried out. In circular geometry, the self-consistent electric field contains zonal flows and geodesic acoustic modes in the confined region. In the scrape-off layer, the electron parallel heat conduction and its boundary condition determine the temperature and electric field, leading to sheared flows at the last closed flux surface.