The first application of time-dependent probability density function (PDF) analysis to the L-H transition in fusion plasmas is presented. PDFs have been constructed using Doppler Backscattering data of fluctuation velocity, u⊥, and turbulence from the edge region of the DIII-D tokamak. This raw time-series data has been sliced into millisecond-long sliding time-windows to create the PDFs. During the transition, the u⊥ PDFs develop strong right tails, which are indicative of turbulence-suppressing shear flows in the plasma edge region; such features and other subtle behaviours are explored using novel information geometry techniques. This paper highlights the power of these techniques to predict the onset of L-H transitions and support theories of predator-prey self-regulation between turbulence and shear flows.
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