Turbulence modeling using test modes

摘要

We present an analytical self-consistent approach, which is able to analyze the processes that appear in the nonlinear stage of turbulence. The results concern drift turbulence in confined plasmas. The method is based on a combined study of test particle and test modes in turbulent plasmas. We show that the main cause of the nonlinear processes that appear beyond the quasilinear stage of turbulence is trajectory trapping or eddying. Trapping introduces quasi-coherent aspects in test trajectory statistics, which lead to large scale correlations, nonlinear damping of the drift modes and generation of the zonal flow modes.