Overview of Results from the DIII-D Negative Triangularity Campaign

In early 2023, a dedicated multiple-week experimental campaign was conducted to qualify the negative triangularity (NT) scenario for future reactors on the DIII-D tokamak after previous initial promising experiments on TCV and DIII-D. During this campaign, high confinement (H_98y,2≥1), high current (q₉₅<3), and high normalized pressure plasmas (β_N>2.5) were achieved at high-injected-power in strongly NT-shaped discharges with δ_avg= - 0.5. The experiments with a lower outer divertor X-point shape covered a wide range of DIII-D operational space (plasma current, toroidal field, electron density and pressure) in contrast to other high-performance ELM-suppression scenarios that have narrower operating windows. Also demonstrated was high normalized density (n_e/n_GW≤2), particle confinement comparable to energy confinement, a detached divertor without impurity seeding, and high core radiation fraction. Plasmas with strong NT maintained a non-ELMing NT-edge with an electron temperature pedestal, exceeding that of typical L-mode plasmas, whereas plasmas with reduced δ_avg~ - 0.18 transition into H-mode. These results are promising for a NT fusion pilot plant and further results on performance, stability, transport, scenario development, and core-edge integration will be presented.