First fully kinetic three-dimensional simulation of the AWAKE baseline scenario

Abstract

The "Advanced Proton Driven Plasma Wakefield Acceleration Experiment" (AWAKE) aims to accelerate leptons via proton-beam-driven wakefield acceleration. It comprises extensive numerical studies as well as experiments at the CERN laboratory. The baseline scenario incorporates a plasma volume of approximately 62 cm 3 . The plasma wavelength is about 1.25 mm and needs to be adequately resolved, using a minimum of 130 points per plasma wavelength, in order to accurately reproduce the physics. The baseline scenario incorporates the proton beam micro-bunching, the concurrent non-linear wakefield growth as well as the off-axis electron beam injection, trapping and acceleration. We present results for the first three-dimensional simulation of this baseline scenario with a full model, using a sufficient resolution. The simulation consumed about 22 Mch of computer resources and scaled up to 32768 cores, thanks to a multitude of adaptions, improvements and optimization of the simulation code PSC. Through this large-scale simulation effort we were able to verify the results of reduced-model simulations as well as identify important novel effects during the electron injection process.

Experimental study of wakefields driven by a self-modulating proton bunch in plasma

“…This effect and the presence of a density ramp at the plasma entrance in the experiment motivated external injection at an angle with respect to the plasma column [31,33,36,37]. Simulation results show that with this injection geometry, test electrons that are eventually accelerated to the highest energy may be confined to a region outside the peak wakefields over the first few meters of plasma, and eventually drop into the wakefields when full SM of the proton bunch has occurred [16].…”

“…To study wakefields after the SM process developed, we externally inject electrons, accelerate them and measure their energy downstream of the plasma. While SM develops, the wakefields' phase velocity evolves and acceleration dynamics are complex [16]. However, once the phase velocity stabilizes, electrons gain energy consistently according to the integrated longitudinal field amplitude they experience from there on.…”

Experimental Study of Wakefields Driven by a Self-Modulating Proton Bunch in Plasma

“…Simulation results show that with this injection geometry, test electrons that are eventually accelerated to the highest energy may be confined to a region outside the peak wakefields over the first few meters of plasma, and eventually drop into the wakefields when full SM of the proton bunch has occurred [16]. It is clear from these results that the charge capture and acceleration processes are very intricate when injecting at an angle and in evolving wakefields.…”

“…To study wakefields after the SM process developed, we externally inject electrons, accelerate them and measure their energy downstream of the plasma. While SM develops, the wakefields phase velocity evolves and acceleration dynamics are complex [16]. However, once the phase velocity stabilises, electrons gain energy consistently according to the integrated longitudinal field amplitude they experience from there on.…”

Force exerted on particle bunch propagating near plasma-vacuum boundary

“…In studies of novel accelerators [1,2], the setup sometimes appears when an ultra-relativistic charged particle bunch propagates parallel or at a shallow angle to a vacuum-plasma boundary [3][4][5], either in the plasma or in the vacuum. The electromagnetic fields induced by the boundary can deflect [3], attract [4], or destroy [5] the bunch, so the boundary effect is of practical importance. In this paper, we derive analytical expressions for these fields under the assumption of linear plasma response and approximate them by elementary functions wherever possible.…”