# Distinct turbulence saturation regimes in stellarators

## TL;DR

This paper identifies two distinct turbulence saturation regimes in stellarators, revealing how magnetic geometry influences turbulence behavior and heat flux scaling through advanced simulations and theory.

## Contribution

It uncovers a second turbulence saturation regime in stellarators characterized by small-scale turbulence and weak zonal flows, expanding understanding beyond tokamak-like regimes.

## Key findings

- Two turbulence regimes identified: strong zonal flows and small-scale turbulence.
- The second regime shows weaker heat flux scaling.
- Magnetic geometry critically influences turbulence behavior.

## Abstract

In the complex 3D magnetic fields of stellarators, ion-temperature-gradient turbulence is shown to have two distinct saturation regimes, as revealed by petascale numerical simulations, and explained by a simple turbulence theory. The first regime is marked by strong zonal flows, and matches previous observations in tokamaks. The newly observed second regime, in contrast, exhibits small- scale quasi-two-dimensional turbulence, negligible zonal flows, and, surprisingly, a weaker heat flux scaling. Our findings suggest that key details of the magnetic geometry control turbulence in stellarators.