Erlangen 2026 – scientific programme

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P: Fachverband Plasmaphysik

P 16: Poster Session Plasma Physics

P 16.24: Poster

Thursday, March 19, 2026, 13:45–15:45, Redoutensaal

GPU Acceleration of Hybrid Fluid-Kinetic Simulations of Runaway Electrons in JOREK — •edoardo carrà, patrik rác, hannes bergström, and matthias hölzl — Max Planck Institute for Plasma Physics

JOREK is a 3D nonlinear, extended magneto-hydrodynamic and hybrid fluid-kinetic code for investigating large scale transient plasma dynamics in realistic tokamak and stellarator fusion plasmas. In high-current tokamaks such as ITER, loss of plasma confinement in a disruption can generate highly energetic ''runaway'' electrons (REs), which can pose a serious threat to plasma-facing components. Understanding and predicting RE dynamics is therefore essential for safe operation of future fusion reactors. While JOREK supports MPI + OpenMP parallelization on CPUs, hybrid RE simulations span widely different timescales, making them computationally prohibitively expensive on conventional CPU architectures. This work addresses that challenge by porting the fluid and kinetic components of hybrid RE simulations to GPUs. Using OpenMP directives, we ensure portability and transparency across hardware platforms while achieving significant performance improvements. We detail the optimization strategies employed and present a comprehensive performance and verification study on NVIDIA and AMD accelerated architectures by benchmarking the linear growth rate of plasma instabilities in the presence of REs and performing a highly non-linear RE beam termination event as first large-scale physics application.

Keywords: Numerical methods; GPU; Plasma physics; Magnetic confinement; Runaway electrons