Slow L-H transitions in DIII-D plasmas

The transitions from the low to the high mode of plasma confinement were studied in a fusion reaction by an experimental technique, which allows an arbitrary slow transition. The periodic turbulent instability bursts were observed near the separatrix, which inhibited the full transitions. The periodic turbulent instability bursts were damped by self generated shear flows and a predator-prey-type relationship was shown to give a good description of the data. The oscillations change to type III edge localized modes as the neutral-beam powder was raised.