摘要
1 Introduction Plasma fluctuations in magnetically confined devices, such as the magnetohydrodynamic （MHD） and drift-type turbulence in tokamaks, possess multiple spatio-temporal scales and spectral anisotropy and/or nonlinear instabilities. coexist and interplay each due to the richness of linear Multi-scale fluctuations may other in a highly turbulent environment so that the characteristics of individual turbulence may be affected, even changed. This important issue has attracted intensive attention recently. As an aspect of such problems, coherent zonal flow and low frequency long wavelength generalized Kelvin-Helmholtz （GKH） fluctuations are generated nonlinearly as a secondary component.
