Temporal coherence and superradiance in plasma wakefield based light sources (Conference Presentation) (Invited Paper)

Coherent light sources, such as free electron lasers, provide bright beams for biology, chemistry, physics and advanced technological applications. As their brightness increases, these sources are also becoming progressively larger, with the longest being several km long (e.g. LCLS). Can we invert this tendency, and bring these sources back to thousands of university, hospital, and industry labs? Plasmas accelerator sources are certainly an attractive solution to this question, but only if their brightness increases several orders of magnitude. Drivers with a higher energy and power will increase the photon yield, but such a dramatic improvement depends on the onset of temporal coherence and superradiance. We intuitively expect superradiance emission when many light emitting particles fit within a radiation wavelength. When this condition is met, all particles radiate coherently as a single giant particle. Instead, here we show that superradiance can occur even when particles are arbitrarily far from each other [J. Vieira et al. Nat. Physics 17, 99 (2021)]. Moreover, by re-analysing the basics of superradiant emission, we explore previously unrecognised configurations leading to superradiance in plasma accelerator based light sources. We explore these concepts in theory and through particle-in-cell simulations complemented by the Radiation Diagnostic for Osiris (RaDiO) [M. Pardal et al, Comp. Phys. Communs. 285, 108634 (2023)].