Parametric study on edge localized modes with a coupled peeling-ballooning triggering model for the KSTAR tokamak

In order to investigate the parametric characteristics of ELMs (Edge Localized Modes) in the KSTAR (Korea Superconducting Tokamak Advanced Research) tokamak, predictive numerical simulations have been carried out by using an integrated core-edge transport modeling code. Pressure-driven ballooning modes and current-driven peeling modes are considered in a coupled form as ELM triggering mechanisms. The simulation results demonstrate that the type of triggering modes has a strong effect on the evolution of pedestal parameters such as temperature, density, and bootstrap current, due to the interferences between stabilizing or destabilizing processes of current density and pressure gradient included in the ballooning and peeling modes criteria. The evolutions of temperature and density profiles at the edge region show a mixed oscillating form of ballooning and peeling modes. The relations between pedestal parameters, such as temperature and density, and ELMs are discussed with the effects of a triggering mechanism and calculation results of pedestal parameters are presented. In addition, the maximum dumped heat fluxes onto divertor plates are given according to various pedestal conditions and heating powers.