A decrease in the edge magnetic and density fluctuations is always seen at the L-H transition in DIII-D. Also, a sudden change of the perpendicular rotation vperpendicular to in the edge has been observed at the transition, which indicates the formation of shear in the radial electric field. This region coincides with the region where the density fluctuations are suppressed. These experimental observations are consistent with earlier theoretical models. Comparisons between the theories and the experimental observations will be discussed.
Constraints on theories provided by fast time response measurements across the L to H transition on DIII-D