Turbulent transport reduction by zonal flows: Massively parallel simulations.

Reports that three-dimensional gyrokinetic simulations of microturbulence in magnetically confined toroidal plasmas with massively parallel computers showed that, with linear flow damping, an asymptotic residual flow develops in agreement with analytic calculations. Nonlinear global simulations of instabilities as supporting the view that turbulence-driven fluctuating zonal flows can reduce turbulent transport; Global and local simulations due to profile variations.