Effects of Pellet ELM Pacing on Mitigation of Type-I ELM Energy Loss in KSTAR and ITER

Full text: Control of type-I ELMy H-mode by pellet injection has been numerically investigated for KSTAR and ITER using a 1.5D core transport code. Predictive modeling on ELMy H-mode in KSTAR successfully shows the consistent plasma dynamics compared with experiments and provides reasonable scaling between H-mode pedestal and ELM characteristics. In order to describe the ELM triggering by pellet injection, a pellet-induced density perturbation model is proposed to carry out an ELM pacing transport simulation. The simulation results of pellet ELM pacing in KSTAR show that the pellet-induced ELMs release the reduced energy bursts compared with spontaneous ELMs, which supports the necessity of high frequency pellet injection for the mitigation of ELMs in tokamaks. The proposed methodology of pellet induced ELM triggering is applied to ITER reference ELMy H-mode scenario so that the control of type-I ELMy H-mode by pellet injection is demonstrated to check an availability of the pellet injection for the mitigation of ELM energy loss in ITER. Consequently, the optimal pellet parameters are discussed to achieve an efficient ELM control in ITER. (author)