Description
High-energy positron beams are a key requirement for next-generation plasma-based accelerator facilities, including the EuPRAXIA conceptual design. In this work, a laser-driven positron source is developed as part of the EuPRAXIA preparatory programme, in collaboration with INFN Frascati, with the aim of delivering beams suitable for injection into advanced acceleration stages.
A full start-to-end simulation framework is developed, encompassing electron beam generation via laser wakefield acceleration, positron production in high-Z converter targets, and subsequent capture and transport. Particle-in-cell and Monte Carlo simulations, coupled with Bayesian optimisation, are used to maximise the high-energy electron charge, enabling efficient positron generation.
The generated positron beams initially exhibit multi-pC charge, broad energy spectra extending into the GeV regime, and ultrashort bunch duration (tens of fs). Through a dedicated beamline, incorporating magnetic optics and energy selection, these beams are transformed into quasi-monoenergetic, low-divergence distributions while preserving phase-space quality. At the beamline exit, the positron beams achieve parameters compatible with plasma-based acceleration requirements, including low energy spread, sub-micrometre normalised emittance, and high peak current, demonstrating their suitability for injection into wakefield acceleration stages.
Post-acceleration proof-of-principle simulations confirm that these beams can be efficiently injected and accelerated to multi-GeV energies, achieving gradients of order 10 GV/m.
This work establishes a scalable, laser-driven positron source tailored for positron plasma acceleration studies, providing a robust platform for investigating beam–plasma interactions and addressing key challenges in positron acceleration physics.