Predicting Zonal Flows -- A Comprehensive Reynolds-Stress Response-Functional from First-Principles-Plasma-Turbulence Computations

TL;DR

This paper develops a first-principles-based Reynolds stress response functional to accurately predict the equilibrium states of turbulence-driven zonal flows in fusion plasmas, advancing understanding of plasma confinement.

Contribution

It introduces a novel, self-consistent Reynolds stress response functional derived from first-principles turbulence simulations, enabling reliable prediction of zonal flow equilibria.

Findings

Reynolds stress response functional successfully predicts zonal flow states.

First-principles turbulence data underpin the functional's accuracy.

The approach advances the modeling of plasma turbulence and confinement.

Abstract

Turbulence driven zonal flows play an important role in fusion devices since they improve plasma confinement by limiting the level of anomalous transport. Current theories mostly focus on flow excitation but do not self-consistently describe the nearly stationary zonal flow turbulence equilibrium state. First-principles two-fluid turbulence studies are used to construct a Reynolds stress response functional from observations in turbulent states. This permits, for the first time, a reliable charting of zonal flow turbulence equilibria.