Dynamics of Fully Nonlinear Drift Wave-Zonal Flow Turbulence System in Plasmas

TL;DR

This paper uses numerical simulations to explore the complex interactions between drift waves and zonal flows in plasmas, revealing how these interactions lead to the formation of coherent structures and reduced particle transport.

Contribution

It introduces a fully nonlinear model of drift wave-zonal flow turbulence that accounts for pseudo-3D drift wave dynamics and their coupling to large-scale zonal flows, advancing plasma turbulence understanding.

Findings

Short-scale drift wave turbulence forms saturated dipolar vortices.

Zonal flows spontaneously develop as monopolar vortices.

Zonal flows suppress cross-field turbulent particle transport.

Abstract

We present numerical simulations of fully nonlinear drift wave-zonal flow (DW-ZF) turbulence systems in a nonuniform magnetoplasma. In our model, the drift wave (DW) dynamics is pseudo-three-dimensional (pseudo-3D) and accounts for self-interactions among finite amplitude DWs and their coupling to the two-dimensional (2D) large amplitude zonal flows (ZFs). The dynamics of the 2D ZFs in the presence of the Reynolds stress of the pseudo-3D DWs is governed by the driven Euler equation. Numerical simulations of the fully nonlinear coupled DW-ZF equations reveal that shortscale DW turbulence leads to nonlinear saturated dipolar vortices, whereas the ZF sets in spontaneously and is dominated by a monopolar vortex structure. The ZFs are found to suppress the cross-field turbulent particle transport. The present results provide a better model for understanding the coexistence of short- and large-scale coherent structures, as well as associated subdued cross-field particle transport in magnetically confined fusion plasmas.