Recent DIII-D experiments have significantly improved the understanding of internal
transport barriers (ITBs) that are triggered close to the time when an integer value of the
minimum in q is crossed. While this phenomenon has been observed on many tokamaks,
the extensive transport and fluctuation diagnostics on DIII-D have permitted a detailed study
of the generation mechanisms of q-triggered ITBs as pertaining to turbulence suppression
dynamics, shear flows, and energetic particle modes. In these discharges, the evolution of …