Extended Data Fig. 1: Electron beam properties at the entrance of COXINEL beamline.
From: Seeded free-electron laser driven by a compact laser plasma accelerator
(a) the charge distribution of several sets of sequential shots at different times over two experimental days. No discrimination or sorting for performance is applied. (b) the mean RMS divergence and mean charge density evaluated for the ± 5% energy range (180–198 MeV) around the COXINEL design central energy (189 MeV) for all shots from a). Selecting shots considered to be of sufficient quality to contribute to FEL amplification, with a mean charge density > 4 pC/MeV throughout the abovementioned energy range (indicated by dashed box), selects 60% of all shots, consistent with experimental observations on FEL amplification signal probability per shot. Considering selected shots, a mean charge density of (6.3 ± 1.4 s.d.) pC/MeV with a mean RMS divergence of (0.80 ± 0.17 s.d.) mrad is found.
