Three-dimensional global fluid simulations of cylindrical magnetized plasmas

Plasma dynamics in cylindrical geometry, with many well diagnosed experiments in operation worldwide, is of fundamental interest. These linear machines can provide an unique testing ground for direct and detailed comparisons of numerical simulations of nonlinear plasma dynamics with experiments. Thus, it is possible to assess the reproductive and predictive capabilities of plasma simulations in unprecedented detail. Here, three-dimensional global fluid simulations of a cylindrical magnetized plasma are presented. This plasma is characterized by the existence of spatially localized sources and sinks. The traditional scale separation paradigm is not applied in the simulation model to account for the important evolution of the background profiles due to the dynamics of turbulent fluctuations. Furthermore, the fluid modeling of sheath boundary conditions, which determine the plasma conditions, are an important ingredient to the code presented here. The linear properties of the model equations are studied and are shown to agree well with experimental observations of linear drift modes. The fully nonlinear simulations are characterized by turbulent fluctuations, which are dominated by low mode numbers in the large radial pressure gradient region. In the far plasma edge, the fluctuations display an intermittent character due to convection within radially extended spatiotemporal potential fluctuations. This paper reports on the model and general code results, while the detailed comparison to a specific experiment is left to a follow-up paper. (c) 2008 American Institute of Physics.