Feedback of zonal flows on wave turbulence driven by small-scale instability in the Charney-Hasegawa-Mima model

Abstract

We demonstrate theoretically and numerically the zonal-flow/drift-wave feedback mechanism in an idealised 2-dimensional model of plasma turbulence driven by a small-scale instability. Zonal flows are generated by a secondary modulational instability of the modes which are directly driven by the primary instability. The zonal flows then suppress the small scales thereby arresting the energy injection into the system, a process which can be described using nonlocal (in scale) wave turbulence theory. Finally, the arrest of the energy input results in saturation of the zonal flows at a level which can be estimated from the theory and the system reaches stationarity without large-scale dissipation.