Scientists funded by the Exascale Computing Project (ECP) have developed WarpX, a modern, performance-portable Particle-in-Cell code that describes the relativistic physics of charged plasma particles for accelerator and laser–plasma physics. WarpX is a single-source, modern C++ code combining the latest algorithmic advancements with mesh refinement; it runs on CPUs and multiple architectures of GPUs for current and forthcoming supercomputers. The team demonstrated for the first time 3D simulations of a three-stage laser-wakefield accelerator, using Summit, the nation’s most powerful supercomputer. Their findings were published in the February 2021 edition of Physics of Plasmas.
WarpX runs simulations of laser–plasma acceleration, a process in which an intense laser pulse excites a nonlinear plasma wake in a gas with an associated accelerating field. Fast and accurate simulation tools are required to study the physics toward configurations that enable the production and acceleration of very small beams with low energy spread and emittance preservation over long distances, as required for a collider. Because the process of accelerating particles is limited to the energy that can be transferred from the laser pulse to the plasma particles, the scientists implemented staging, a process for coupling multiple laser pulses into subsequent acceleration stages and matching the particle beams from one stage to another. So far, the code enabled modeling of chains of up to ten plasma accelerator stages in full 3D. The team also optimized communication buffers in the code, balancing predicted particle beam quality and simulation costs.
The team’s demonstration of WarpX for plasma physics simulations on Summit is an important step toward modeling multistage particle acceleration to advance accelerator research with the goal of chains of tens to hundreds of stages for future collider designs. WarpX is expected to be used for experimental campaigns at the Lawrence Berkeley National Laboratory BELLA laser facility in California as well as implementations in future particle colliders. The scientists work closely with other ECP teams on common solutions related to in situ visualization and compression, input/output, and exploration of local and multidevice fast Fourier transforms.
Vay, J.-L., A. Huebl, A. Almgren, L. D. Amorim, J. Bell, L. Fedeli, L. Ge, et al. 2021. “Modeling of a Chain of Three Plasma Accelerator Stages with the WarpX Electromagnetic PIC Code on GPUs.” Physics of Plasmas 28 (2) (February): 023105. doi:10.1063/5.0028512. http://dx.doi.org/10.1063/5.0028512.