Zonal Flow Patterns: How Toroidal Coupling Induces Phase Jumps and Shear Layers

A new, frequency modulation mechanism for zonal flow pattern formation is presented. The model predicts the probability distribution function of the flow strength as well as the evolution of the characteristic spatial scale. Magnetic toroidicity-induced global phase dynamics is shown to determine the spatial structure of the flow. A key result is the observation that global phase patterning can lead to zonal flow formation in the absence of turbulence inhomogeneity.

Figure 1

Red: phase lattice; dashed black: continuous limit of the phase lattice.

Figure 2

Top figure: global phase gradient shock induced by magnetic toroidicity; bottom figure: staircaselike ZF bands induced by the shocks.