# Verification of the global gyrokinetic stellarator code XGC-S for linear ion temperature gradient driven modes

## TL;DR

This paper benchmarks the extended XGC-S gyrokinetic code for stellarator configurations, demonstrating its accuracy in modeling ion temperature gradient-driven microinstabilities and showing good agreement with established codes in tokamak and stellarator geometries.

## Contribution

It introduces and validates XGC-S for stellarator modeling, extending the original XGC code to 3D configurations and benchmarking its performance against other gyrokinetic codes.

## Key findings

- XGC-S shows good agreement with XGC1, ORB5, and GENE in tokamak geometry.
- XGC-S accurately reproduces mode spectra and growth rates in Wendelstein 7-X stellarator.
- Benchmark results confirm XGC-S's reliability for stellarator turbulence studies.

## Abstract

XGC (X-point Gyrokinetic Code) is a whole-volume, total-f gyrokinetic particle-in-cell code developed for modelling tokamaks. In recent work, XGC has been extended to model more general 3D toroidal magnetic configurations, such as stellarators. These improvements have resulted in the XGC-S version. In this paper, XGC-S is benchmarked for linear electrostatic ion temperature gradient-driven microinstabilities, which can underlie turbulent transport in stellarators. An initial benchmark of XGC-S in tokamak geometry shows good agreement with the XGC1, ORB5, and global GENE codes. A benchmark between XGC-S and the EUTERPE global gyrokinetic code for stellarators has also been performed, this time in geometry of the optimised stellarator Wendelstein 7-X. Good agreement has been found for the mode number spectrum, mode structure, and growth rate.