Extending the operational space of the high bootstrap current fraction scenario on DIII-D towards ITER steady-state

Recent DIII-D experiments have extended high β_p plasmas to higher performance, meeting the required normalized parameters for ITER Q=5 steady state operation. Plasmas with H₉₈ ≥1.5 and β_N ≥4 have been achieved at q_min≥2 and β_T≥3%, and sustained for about a current diffusion time. The normalized fusion performance G₉₈=H₉₈β_N/q² in DIII-D high β_p experiments reaches the predicted value for ITER from high β_p Q=5 modeling. Strong internal transport barrier leads to a high confinement core with bootstrap current fraction ≥ 80% and line-averaged density at the Greenwald limit. No core impurity accumulation has been observed even with a density ITB. In addition, high β_p plasmas with true single null ITER plasma shape have been obtained for the first time on DIII-D. Achieved normalized parameters (q₉₅~8.0, β_N >2.7 and H₉₈~1.4) are relevant to the ITER high β_p target. With ITER-like shape, excellent core-edge integration with simultaneously sustained ELM suppression, complete divertor detachment (DoD >10), and high confinement core (β_N>2.5) has been demonstrated with neon seeding. The ITB compensates the pedestal reduction from divertor detachment and promotes core-edge integration. These results confirm the high β_p scenario as a highly promising candidate for ITER steady-state operation.