Self-consistent turbulent convection in a magnetized plasma

Abstract

It has been shown that low-frequency vortex convection, which is self-consistently developed in a magnetized plasma, may lead to nondiffusive transport processes similar to those observed in various systems of the plasma magnetic confinement. To theoretically analyze such a convection, an approach is proposed on the basis of the direct computer simulation of the quasi-two-dimensional dynamics of a weakly dissipative plasma with the use of adiabatically reduced hydrodynamic-type equations. The derived equations ensure the description of both relatively fast nonlinear convective flows and slower resulting transport processes and allow the simulation of the plasma evolution at sufficiently long times comparable with the plasma lifetime. The simulation shows that the development of the convection leads to the formation of nonlinear large-scale stochastic vortex structures, which exhibit broad power-law frequency and wavenumber spectra, as well as the non-Gaussian statistics of fluctuations, and corresponds to the notion of structure turbulence. The resulting transport processes are nonlocal and nondiffusive and have a number of characteristic properties similar to those observed in real experiments. The self-consistency of the pressure and density profiles in the plasma, L-H transitions, impurity pinch, etc., are among these properties.