Gyrokinetic simulations of plasma turbulence in a Z-pinch using a moment based approach and advanced collision operators

TL;DR

This paper presents the first nonlinear gyrokinetic simulations of plasma turbulence in a Z-pinch using a moment-based approach with advanced collision models, showing good agreement with existing codes and highlighting the impact of collisions on turbulence regulation.

Contribution

It introduces a novel nonlinear gyrokinetic simulation method based on Hermite-Laguerre moments with advanced collision operators for Z-pinch turbulence.

Findings

Good agreement with GENE code in collisionless regime

Collision operator choice affects turbulence suppression by zonal flows

Including collisions improves convergence of the moment approach

Abstract

The first nonlinear gyrokinetic simulations obtained using a moment approach based on the Hermite-Laguerre decomposition of the distribution function are presented, implementing advanced models for the collision operator. Turbulence in a \modif{two-dimensional} Z-pinch is considered within a flux tube configuration. In the collisionless regime, our gyromoment approach shows very good agreement with nonlinear simulations carried out with the continuum gyrokinetic code GENE, even with fewer gyromoments than required for the convergence of the linear growth rate. By using advanced linear collision operators, the role of collisions in setting the level of turbulent transport is then analyzed. The choice of collision operator model is shown to have a crucial impact when turbulence is quenched by the presence of zonal flows. The convergence properties of the gyromoment approach improve when collisions are included.