Regime of very high confinement in the boronized DIII-D tokamak

Following boronization, tokamak discharges in DIII-D have been obtained with confinement times up to a factor of 3. 5 above the ITER89-P L-mode scaling and 1. 8 times greater than the DIII-D/JET H-mode scaling relation. Very high confinement phases are characterized by relatively high central density with n₄ (0) 110^20 m^-3, and central ion temperatures up to 13. 6 keV at moderate plasma currents (1. 6 MA) and heating powers (12. 5--15. 3 MW). These discharges exhibit a low fraction of radiated power, P25%, Z₄₅₅ (0) close to unity, and lower impurity influxes than comparable DIII-D discharges before boronization.