Present Status and Prospects of Research on Zonal Flow 2.Theoretical Progress of Zonal Flow

Abstract

An overview of the theory of zonal flows is presented. The contents include description of the mechanism by which zonal flows are generated, there relation between turbulence and zonal flows, and transport in drift wave-zonal flow turbulence. The physics of zonal flows is a prototypical example of a paradigm shift from the linear-local-deterministic view to the nonlinear-nonlocal-statistical view of structure formation in plasmas. Research regarding the turbulence-zonal flow system in laboratory plasma will deepen our understanding of this aspect of nature.