ITG sideband coupling models for zonal flows

Artikel i vetenskaplig tidskrift, 2011

Four-wave interaction model between ITG mode and zonal flow was derived using fluid equations. In this model, the zonal flow is excited non-linearly by ITG turbulence via Reynolds stress. Numerical simulations show that the system allows for a small range above the ITG threshold where the zonal flow can stabilize an unstable ITG mode, effectively increasing eta(i) threshold, an effect which has been called the Dimits shift. However, the shift is smaller than in known cases such that in the Cyclone base.