Understanding nonlinear saturation in zonal-flow-dominated ion temperature gradient turbulence

Understanding nonlinear saturation in zonal-flow-dominated ion temperature gradient turbulence

We propose a quantitative model of ion temperature gradient driven turbulence in toroidal magnetized plasmas. In this model, the turbulence is regulated by zonal flows, i.e. mode saturation occurs by a zonal-flow-mediated energy cascade (‘shearing’), and zonal flow amplitude is controlled by nonlinear decay. Our model is tested in detail against numerical simulations to confirm that both its as...

Zonal flow generation in ion temperature gradient mode turbulence

In the present work the zonal flow ~ZF! growth rate in toroidal ion-temperature-gradient ~ITG! mode turbulence including the effects of elongation is studied analytically. The scaling of the ZF growth with plasma parameters is examined for typical tokamak parameter values. The physical model used for the toroidal ITG driven mode is based on the ion continuity and ion temperature equations where...

Coherent structures in ion temperature gradient turbulence-zonal flow

Fine-Scale Zonal Flow Suppression of Electron Temperature Gradient Turbulence

Abstract. It is found in collisionless Electron Temperature Gradient (ETG) turbulence simulations that, while zonal flows are weak at early times, the zonal flows continue to grow algebraically (proportional to time). These fine-scale zonal flows have a radial wave number such that krρi > 1 and krρe < 1. Eventually, the zonal flows grow to a level that suppresses the turbulence due to ExB shear...

Gyrokinetic Studies of Ion Temperature Gradient Turbulence and Zonal Flows in Helical Systems

Gyrokinetic theory and simulation results are presented to investigate regulation of ion temperature gradient (ITG) turbulence due to E × B zonal flows in helical systems. In order to examine effects of changes in helical magnetic configuration on anomalous transport and zonal flows, magnetic field parameters representing the standard and inward-shifted configurations of the Large Helical Devic...