Negative triangularity as a possible tokamak scenario

Kikuchi, Mitsuru; Takizuka, Tomonori*; Furukawa, Masaru*

Recent scaling of SOL e-folding length by Goldston shows pessimistic prediction to ITER and DEMO. This seems caused by the SOL acceleration mechanism found by Takizuka. In the negative D shaped plasma, this SOL acceleration may be significantly reduced. Negative D also has TEM eigen mode structure tilted poloidally and confinement in L mode is two times of L-mode. Based on these facts, we discuss possibility of negative D as a possible operation candidate of tokamak.