Exascale Implicit Kinetic Plasma Simulations on El~Capitan for Solving the Micro-Macro Coupling in Magnetospheric Physics

TL;DR

This paper demonstrates a highly scalable, GPU-accelerated implicit Particle-in-Cell simulation framework that enables detailed kinetic modeling of planetary magnetospheres at unprecedented scales, capturing multi-scale plasma physics.

Contribution

The work introduces a GPU-optimized, fully kinetic implicit PIC simulation capable of modeling global magnetospheres at scales previously unattainable, with innovations in algorithms and data management.

Findings

Simulated magnetospheres of Mercury and Ganymede at global scales.

Achieved up to 10x larger time steps without losing accuracy.

Utilized advanced GPU kernels and data compression techniques.

Abstract

Our fully kinetic, implicit Particle-in-Cell (PIC) simulations of global magnetospheres on up to 32,768 of El Capitan's AMD Instinct MI300A Accelerated Processing Units (APUs) represent an unprecedented computational capability that addresses a fundamental challenge in space physics: resolving the multi-scale coupling between microscopic (electron-scale) and macroscopic (global-scale) dynamics in planetary magnetospheres. The implicit scheme of iPIC3D supports time steps and grid spacing that are up to 10 times larger than those of explicit methods, without sacrificing physical accuracy. This enables the simulation of magnetospheres while preserving fine-scale electron physics, which is critical for key processes such as magnetic reconnection and plasma turbulence. Our algorithmic and technological innovations include GPU-optimized kernels, particle control, and physics-aware data compression using Gaussian Mixture Models. With simulation domains spanning 100-1,000 ion skin depths, we reach the global scale of small-to-medium planetary magnetospheres, such as those of Mercury and Ganymede, which supports fully kinetic treatment of global-scale dynamics in systems previously out of reach for fully kinetic PIC codes.