Full-f electromagnetic gyrokinetic turbulence simulations of the edge and scrape-off layer of ASDEX Upgrade with GENE-X*

Understanding and predicting the effects of turbulence in the edge and scrape-off layer (SOL) of magnetic fusion devices is known to be a critical step on the path towards a truly predictive capability. While there has been progress along these lines in recent years, especially with the help of Braginskii-type fluid codes, the development of full-f electromagnetic gyrokinetic codes for the edge and SOL in general diverted geometries remains the ultimate goal. 

Here, we present a novel grid-based ("continuum") code of this comprehensive type, GENE-X, along with applications to ASDEX Upgrade. GENE-X [1] is a newly developed version of the widely used GENE [2] code. It is aimed at describing edge and SOL turbulence and implements a full-f electromagnetic gyrokinetic model. GENE-X is able to handle diverted geometries in single-null, double-null and advanced divertor configurations by implementing the so-called flux-coordinate independent approach [3]. 

The simulations presented here are performed at both reduced and realistic ion-to-electron mass ratio on millisecond time scales, studying profile evolution. We compare the resulting plasma profiles to experimental measurements and to previous simulations with the Braginskii fluid code GRILLIX [4]. Based on the results, we discuss the influence of the ion-to-electron mass ratio and collisional effects on gyrokinetic SOL turbulence.

[1] D. Michels et al., Comput. Phys. Commun. 264 (2021) 107986

[2] F. Jenko et al., Phys. Plasmas 7 (2000) 1904

[3] F. Hariri et al., Comput. Phys. Commun. 184 (2013) 2419

[4] W. Zholobenko et al., Plasma Phys. Control. Fusion 63 (2021) 034001