Integrated pedestal and core modeling of Joint European Torus (JET) triangularity scan discharges

Simulations of four Joint European Torus (JET) [Rebut et al., Nucl. Fusion 25, 1011 (1985)] type I ELMy high confinement mode discharges in a triangularity scan are carried out using the JETTO integrated modeling code [Erba et al., Plasma Phys. Contolled Fusion 39, 261 (1997)] with a predictive core transport model and a pedestal model that includes the effects of edge localized modes (ELMs). The pedestal pressure gradient is limited by the magnetohydrodynamic (MHD) ballooning mode instability, which triggers ELM crashes in these simulations. The validation of the pressure gradient limit used in the simulations is confirmed by a stability analysis carried out using the HELENA and MISHKA codes [Mikhailovskii et al., Plasma Phys. Rep 23, 713 (1997)]. The MHD stability analysis includes infinite-n ideal ballooning, finite-n ballooning, and low-n kink/peeling modes. It is shown that higher triangularity plasmas have easier access to the second stability region, which allows the edge pressure gradients in the higher triangularity discharges to increase to higher levels.