The spatiotemporal behavior of the interaction between turbulence and flows has been studied close to the L-H transition threshold conditions in the edge region (ρ≥0.7) of TJ-II plasmas. The temporal dynamics of the interaction displays an oscillatory behavior with a characteristic predator-prey relationship. The spatial evolution of this turbulence-flow oscillation pattern has been measured, showing both radial outward and inward propagation velocities of the turbulence-flow front. The results indicate that the edge shear flow linked to the L-H transition can behave either as a slowing-down, damping mechanism of outward propagating turbulent-flow oscillating structures, or as a source of inward propagating turbulence-flow events.

The physical mechanisms behind the L-H transition have been experimentally studied in the TJ-II plasmas. The spatial, temporal and spectral structure of the interaction between turbulence and flows has been studied close to the L-H transition threshold conditions. The temporal dynamics of the turbulence-flow interaction displays a predator-prey relationship and both, radial outward and inward propagation velocities of the turbulence-flow front have been measured. Moreover, the turbulence scales involved in the energy transfer of the predator-prey process have been identified. © 2012 IOP Publishing Ltd.