FPGA Based Hybrid Computing Platform for ESS Linac Simulator

This paper presents a scalable and high-throughput hybrid computing platform for the real-time multi-particle based Linac (Linear accelerator) simulation model to be used at the European Spallation Source (ESS). The multi-particle simulation model with non-linear modeling is needed to provide a realistic behavior of the particle beam for reducing the losses at the superconducting structures. The computation complexity of the simulations can reach 10¹² matrix multiplication operations for a test case of 10⁶ beam particles simulated over 10⁶ cells. An OpenCL (Open Computing Language) based framework is used to map the processing intensive parts of the simulation model efficiently to any configuration of a CPU-, GPU- and FPGA-based platform. Optimizations using data precision strategies have also been explored to further improve the throughput after reaching memory access saturation. We are able to achieve up to $89 \times$ speed up compared to a C++ benchmark of the same system.