EZ: An Efficient, Charge Conserving Current Deposition Algorithm for Electromagnetic Particle-In-Cell Simulations

We present EZ, a novel Current Deposition algorithm for particle-in-cell simulations, which calculates the current density field due to macro-particle motion within a time step by solving the electrodynamic continuity equation. Being a charge conserving hybridization of \textbf{E}sirkepov's method and \textbf{Z}igZag, we refer to it as ``EZ'' as shorthand for ``Esirkepov meets ZigZag''. EZ achieves the same level of charge conservation as the commonly used method by Esirkepov, yet reaches higher performance for macro-particle assignment-functions up to third-order. Key considerations of its implementation in PIConGPU, an open source, C++, performance portable, fully relativistic 3D3V particle-in-cell code, are outlined in addition to the detailed description of EZ along with remarks on its optimization and customization.