Exploring ELM-free and ELM suppressed operation for CFETR

With the proposed China Fusion Engineering Test Reactor (CFETR) as a next step in China fusion development, identifying stable operation regimes with good performance and acceptable heat and particle control is a key goal of CFETR engineering design. To achieve this goal Type I ELMs with large amplitudes have to be avoided in order to prevent excessive erosion of the divertor target material.

This study investigates various methods to achieve robust grassy ELM or ELM-free operations in CFETR. Using a combination of EPED and ELITE, we map out the operating space of the CFETR pedestal,and explore the changes in ELM characteristics along the marginal stability boundary. The pedestal current and density for optimized performance is identified. The ELM behavior is classified using BOUT++ simulation. Ways to suppress or avoid ELMs will be discussed.