Energy transfer and shear flow generation in plasma interchange turbulence

Energy transfer and ${\mathbf E} \times {\mathbf B}$ shear flow generation in plasma interchange turbulence are examined in a flux-driven system with both closed and open magnetic field lines. The nonlinear evolution of interchange turbulence shows the presence of two regimes characterized by low and high ${\mathbf E} \times {\mathbf B}$ flow shear. In the first regime, the mean ${\mathbf E} \times {\mathbf B}$ shear flow is at a relatively low level and the large-amplitude ${\mathbf E} \times {\mathbf B}$ velocity fluctuation dominates in the nonlinear saturated state. By increasing the heat flux that drives the system, the fluctuation-induced energy transfer becomes stronger and a transition to the second regime occurs, in which a high mean ${\mathbf E} \times {\mathbf B}$ flow shear is generated.