Minisymposium Presentation

Understanding and predicting turbulence-driven transport across the edge and scrape-off layer (SOL) are crucial for the success of magnetic confinement fusion devices. However, the challenging plasma conditions in the edge and SOL require first-principles gyrokinetic (GK) simulations. To address these challenges, the GENE-X code has been developed to solve the full-f GK model in magnetic geometries with X-points. While GENE-X simulations provide an accurate description of edge and SOL turbulence, their computational cost remains prohibitively high, often requiring millions of CPU hours and spanning over weeks or months. Although GPUs and exascale architectures offer potential speed-ups, further advances in numerical algorithms are essential.We present a novel velocity-space spectral method, recently implemented in the GENE-X code for the first time. The numerical implementation is rigorously verified, and performance benchmarks are conducted. Through a detailed analysis of spectral simulations, we demonstrate excellent agreement with Eulerian (grid-based) GENE-X simulations, validated against experimental measurements. This allows us to identify the minimum spectral resolution required to achieve accurate results, comparable to those from grid-based simulations. We find that the spectral approach enables a significant computational speed-up, reducing the velocity-space resolution by a factor of 50. The first applications in reactor-relevant scenarios will be presented.