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

Abstract

The dynamical interplay between turbulent particle transport (Γ) and Reynolds stress (ℜ) 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 Γ and ℜ 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 E×B 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 (k_{θ}ρ_{s}>0.6) are shown to play a key role via a mutual stabilization-destabilization process.