Coupled drift-wave-zonal flow model of turbulent transport in the tokamak edge

Abstract

Analytical investigations of several linear and nonlinear features of drift resistive ballooning mode (DRBM) have been carried out. The physics of this mode has been elucidated, as well as the parameter space where it is important. Based on the linear theory, it is shown that the growth of the high-m DRBM is crucially dependent on the poloidal mode number and finite Larmor radius effects i.e., drift parameter). The modulational instability of the zonal flow in a background of DRBM turbulence (using the parametric instability methods) has also been presented. Furthermore, an estimate of the particle transport due to DRBM (with its amplitude level limited by zonal flows) has also been computed. Finally, comparison with the transport estimated from the mixing length arguments and earlier simulations by Rogers and Drake [ B. N. Rogers and J. F. Drake, Phys. Rev. Lett. 81, 4396 (1998) ] are also presented.