Exploring zonal flow mediated saturation on stellarators

TL;DR

This paper investigates how the geometry of stellarator magnetic fields influences zonal flow activity and saturation, revealing key geometric factors that affect turbulence regulation in stellarators.

Contribution

It provides new insights into the geometric dependence of zonal flow damping and drive in stellarators, aiding the development of reduced turbulence models.

Findings

Variation in linear zonal flow damping correlates with nonlinear drive.

Key geometric features control zonal flow effects.

Understanding this balance is crucial for modeling turbulent transport.

Abstract

In stellarators, zonal flow activity depends sensitively on geometry of the three dimensional magnetic field, via an interplay of mechanisms that is not fully understood. In this work, we investigate this by studying three magnetic configurations of the Wendelstein 7-X stellarator. We find that variation in linear zonal flow damping is accompanied by variation in nonlinear drive, and identify key geometric features that control these effects. Understanding the resulting balance is important for the development of reduced models of turbulent transport.