Pushing the Frontier in the Design of Laser-Based Electron Accelerators with Groundbreaking Mesh-Refined Particle-In-Cell Simulations on Exascale-Class Supercomputers

150 word max) We present a first-of-kind mesh-refined (MR) massively parallel Particle-In-Cell (PIC) code for kinetic plasma simulations optimized on the Frontier, Fugaku, Summit, and Perlmutter supercomputers. Major innovations, implemented in the WarpX PIC code, include: (i) a three level parallelization strategy that demonstrated performance portability and scaling on millions of A64FX cores and tens of thousands of AMD and Nvidia GPUs (ii) a groundbreaking mesh refinement capability that provides between 1.5x to 4x savings in computing requirements on the science case reported in this paper, (iii) an efficient load balancing strategy between multiple MR levels. The MR PIC code enabled 3D simulations of laser-matter interactions on Frontier, Fugaku, and Summit, which have so far been out of the reach of standard codes. These simulations helped remove a major limitation of compact laser-based electron accelerators, which are promising candidates for next generation high-energy physics experiments and ultra-high dose rate FLASH radiotherapy.

Automated summary

This paper presents a mesh-refined massively parallel Particle-In-Cell (PIC) code optimized for kinetic plasma simulations on supercomputers. The code incorporates innovative strategies such as parallelization, mesh refinement, and load balancing, enabling 3D simulations of laser-matter interactions on high-performance supercomputers. The simulations overcome limitations in laser-based electron accelerators, which have potential applications in high-energy physics experiments and FLASH radiotherapy.