Generation of large-scale flows due to the small-scale drift-wave turbulence

Abstract

Summary form only given, as follows. Numerical simulation is performed of the two-dimensional plasma with to a view studying the generation of large-scale flows through the short-scale drift-wave turbulence. The electrostatic turbulence is modeled by Hasegawa-Mima equation with or without an external forcing. Both the shift of the frequency and the nonlinear growth rate of the long-wavelength drift wave will be investigated and the comparison will be made with the proposed predator-prey dynamical system. Without the waves, the energy cascades from the smaller scales to the larger ones and accumulates at the largest possible scale. However, the energy cascade is impeded by the presence of the waves whose frequencies are of the same order as the effective vorticity. As a result, under certain conditions, large-scale zonal flows may develop in the neutral fluids. In addition, plasmas have another important scale in the ion gyro-radius, which may keep the energy cascade from reaching the largest scale and help developing the coherent vortices In this poster, detailed analyses will be presented. regarding the formation of the large-scale flows in terms of the various parameters such as the external forcing, the ion gyro-radius, the dissipation and the system size.