Generation mechanism and nonlinear dynamics of zonal modes in Alfvenic wave flucutations

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Zonal mode physics including convective cells in electromagnetic (EM) plasmas in a framework of nonlinear Alfven wave theory has been investigated based on gyrofluid simulations of multi-scale EM turbulence. Main findings are summarized as (1) the spectral characteristics of micro-turbulence is significantly modified by the feedback reaction of zonal flows including the GAMs and the secondary low-frequency long wavelength structures through the spectral scattering via nonlinear mode coupling ; (2) Larger magnetic island including the zonal fields induces a new global-type short wavelength ion-scale instability due to the collapse of ion temperature island involving the zonal temperature dynamics ; (3) A concept of cross-scale dynamo action is proposed as an alternative of the anomalous resistivity theory for fast magnetic reconnection ; (4) The zonal pressure corrugation can lead a bursty turbulent transport via nonlocal mode coupling.