Interplay of turbulent transport and Reynolds stress in drift-wave turbulence

The dynamical interplay between turbulent particle transport and Reynolds stress at the edge of toroidal magnetically confined plasmas is experimentally investigated on the basis of the cross-coupling between density and potential fluctuations in drift-wave turbulence. Both and are found to be temporally anticorrelated, with a dynamical coupling of the density and potential fluctuations as an agent in their interplay. The density-potential coupling is shown for the first time to be dynamically related to the Reynolds stress in agreement with the vortex-tilting mechanism. Consistently, a temporal deterioration of the coupling links the evolution of particle transport to the drop in the Reynolds stress. Small-scale contributions are shown to play a key role via a mutual stabilization-destabilization process.