Five-field simulations of peeling-ballooning modes using BOUT++ code

The simulations of edge localized modes (ELMs) with a 5-field peeling-ballooning (P-B) model using BOUT++ code are reported in this paper. In order to study the particle and energy transport in the pedestal region, the pressure equation is separated into ion density and ion and electron temperature equations. Through the simulations, the length scale Ln of the gradient of equilibrium density ni0 is found to destabilize the P-B modes in ideal MHD model. With ion diamagnetic effects, the growth rate is inversely proportional to ni0 at medium toroidal mode number n. For the nonlinear simulations, the gradient of ni0 in the pedestal region can more than double the ELM size. This increasing effect can be suppressed by thermal diffusivities χ∥, employing the flux limited expression. Thermal diffusivities are sufficient to suppress the perturbations at the top of pedestal region. These suppressing effects lead to smaller ELM size of P-B modes.