Aspects of flow generation and saturation in drift-wave turbulence

The generation of large-scale flows by turbulence in plasmas and fluids has attracted a great deal of attention in the last years. The interplay between turbulence and sheared zonal flows has been identified as a possible candidate to explain the transition from L to H mode as well as the setup of transport barriers in general, while radial flows are made responsible for increased levels of transport. Using simplified equations for low-frequency plasma turbulence of the drift-wave type we consider some general aspects of flow generation and address the problem of saturation of drift-wave turbulence.