Porting Negative Triangularity plasmas to the WEST tokamak

Diverted plasmas with a Negative Triangularity (NT) cross sectional shape have been developed on the WEST tokamak and were sustained for several current diffusion times. This innovative configuration is attractive thanks to its potential for solving the long-standing core-edge integration problem. Recently, significant power degradation of confinement was observed in divertor detached conditions on graphite devices, which motivates further studies in a full tungsten environment. The WEST team successfully developed lower single plasmas at the highest magnetic field of 3.7 T, scanning upper triangularity in the region [-0.3, +0.1] and edge safety factor between 4.5 and 9. Plasmas were heated with lower hybrid auxiliary power up to 1.5 MW. At these low auxiliary power levels, the core confinement quality and the density limit are similar between NT plasmas and their positive triangularity counterparts, consistent with prior experience on graphite devices. Future experiments will leverage the already developed scenario at higher auxiliary power levels to probe the sustainment of high confinement, the accessibility to increased density limit and plasma detachment conditions.