Optimizing Parallel Computation of Collision Rates and Fusion Reactivity in Simulated Deuterium-Tritium Plasmas*

This paper presents a study of the collision processes in a one-dimensional particle-in-cell plasma model designed to simulate electrostatic motion of deuterium and tritium ions, as well as their corresponding electrons, under fusion conditions. We analyze the inherit challenges in computing collision rates posed by the different time scales of ion and electron movement and the inherent order N² computational complexity of this problem. To address these challenges, we implement parallelization strategies utilizing graphical processing units (GPUs) within a supercomputer cluster and discuss how Message Passing Interface (MPI) and Compute Unified Device Architecture (CUDA) are used to distribute the computation throughout the GPUs in the cluster.  Our findings, include detailed comparisons of electron-electron, electron-ion, and ion-ion collision rates, as well as fusion reactivity with theoretical predictions and previous experimental data. This work showcases the potential of high-performance computing in advancing plasma research, offering a framework for future studies that seek to explore complex plasma dynamics in fusion environments.