First Integration of negative triangularity plasmas with high core radiation fraction

High performance, high power, highly radiative and robustly ELM free discharges have been achieved in negative triangularity (NT) shape enabled by the DIII-D armored campaign. A wide parameter range has been achieved with a core radiated power fraction up to 0.85 and a Greenwald density greater than 1 in some cases. Core radiation limits have been explored and achieved for Ne, Ar and Kr as seeded impurities while scanning key parameters such as plasma density, current, toroidal magnetic field direction, impurity rate and gas seeding location. It was also found that adding N₂ mantle radiation leads to a reduction in heat flux at the target while the energy confinement remained constant or improved. Matched discharges at high core radiation fraction where only the toroidal field direction was changed yield to similar global parameters but very different divertor conditions which are analyzed with SOLPS-ITER modeling. BES measurements reveal reduction in turbulence during the impurity injection which correlates with changes in transport. High core radiation fraction with BetaN values greater than 2 have been sustained as long as impurity accumulation was controlled to prevent radiative collapse and excess dilution, highlighting a path for an optimized core-edge and power exhaust solution with NT shaping.