Investigation of ITG turbulence in cylinder geometry within a gyrokinetic global PIC simulation: influence of zonal flows and a magnetic well

A gyrokinetic global nonlinear particle-in-cell (PIC) method is applied to calculate ion-temperature-gradient (ITG) driven turbulence and the resulting anomalous heat transport in a θ-pinch. The level of turbulence and transport are strongly decreased by poloidal zonal E x B flows. The radial electric field, Er, leading to these zonal flows is generated by the turbulence. Thus, a magnetic field with a well according to a finite-β equilibrium and leading to a decrease in the linear growth rates of ITG-modes influences the formation of the radial electric field. The gyrokinetic global nonlinear TORB code has been modified to investigate the consequences for the turbulence level