Theoretical studies towards a negative triangularity tokamak power plant

Experimental observations show that negative triangularity plasma shaping can significantly improve the energy confinement time of tokamaks. Moreover, unlike the standard positive triangularity shape, negative triangularity plasmas typically cannot access H-mode. Together these two facts may enable an attractive power plant design – the plasma can be heated to reactor-relevant conditions while remaining in L-mode to avoid the material survivability concerns associated with ELMs, yet still achieve sufficiently good confinement for high fusion gain. This potential has motivated the creation of EUROfusion’s Theory, Simulation, Verification, and Validation (TSVV) project on negative triangularity, which is investigating the feasibility of a negative triangularity power plant. In this talk, we will synthesize the most important results including the physical reasons behind the confinement time improvement, how performance scales to new parameter regimes (like spherical tokamaks), insights from reduced transport modeling, the scrape-off layer width, and more. We will connect these results to recent experiments and comment on the prospects for a negative triangularity power plant.