Effects of Ripple-Induced Ion Thermal Transport on H-mode Plasma Performance
The effects of ripple-induced thermal ion transport on the performance of ELMy H-mode plasmas are investigated in predictive transport simulations. It is shown that ripple-induced transport can have a profound impact on the severity of ELMs and confinement. If the ripple-induced additional ion thermal transport is very edge-localized, the ELM frequency increases, whereby the energy and particle losses per ELM decrease, and there is a reduction of confinement due to an effective narrowing of the pedestal. A wider perturbation can lead to a reduced ELM frequency and somewhat improved overall confinement thanks to large edge losses between the ELMs resulting in an increase in the time average temperature at the top of the pedestal.