Plasma-based compression of electron beams

The generation of electron beams with attosecond pulse durations and ultra-high peak currents would open opportunities in applications as diverse as high-energy colliders, strong field quantum electrodynamics, and laboratory astrophysics. Compressing such beams while maintaining beam quality, however, remains a challenge. We demonstrate the use of plasma-based compression to achieve such extreme beams by exploiting the large acceleration gradients present in plasma wakefields to chirp the beam. By adding chirps on the order of 0.1 - 1 GeV/um, several orders of magnitude beyond what is possible using conventional techniques, subsequent compression in a dispersive element can produce bunches with durations approaching 10 nm and peak currents approaching 1 MA. We study, using particle-in-cell simulations, how plasma-based compression scales with beam and plasma properties and identify optimal conditions for different applications. Experiments at the FACET-II facility at SLAC National Accelerator Laboratory confirm the generation of highly-chirped electron beams using a beam-driven plasma wakefield accelerator. Such beams can then be compressed to 100 nm-scale durations in a downstream magnetic chicane. Insights from this work will help design the next-generation of high-brightness beams for new frontiers in scientific research.