Instability of convective cells in ion temperature gradient turbulence

It has been demonstrated using numerical simulation of two-dimensional ion temperature gradient (ITG) equations that a periodic array consisting of large scale convective cells is subject to shear flow instability. A dynamically global and self-consistent evolution of linearly unstable modes, close to marginal instability, leads to the formation of poloidal shear flow through the process of peeling-instability. The saturated state thus comprises radially localized and polloidally extended length scales, namely, zonal flows. The zonal flows are predominantly led by the perturbed shear flow, whose growth rate is larger than the linear ITG instability.