The COXINEL seeded free electron laser driven by the HZDR laser plasma acceleration

Laser Plasma Accelerators (LPAs), reaching gigavolt-per-centimeter accelerating fields, can generate high peak current, low emittance and GeV class electron beams that can be qualified by a Free Electron Laser (FEL) application. We report here on the commissioning of the COXINEL beamline driven by the HZDR plasma accelerator and experimental demonstration of FEL lasing at 270 nm in a seeded configuration. We also present the transport and characterization of LPA based beams using different imaging systems along the beamline. The use of a streak camera and a UV spectrometer enable to align the seed and the electron beam in the temporal, spectral and transverse domains. Furthermore, the appearance of interference fringes, resulting from the interaction between the phase-locked emitted radiation and the seed, confirms longitudinal coherence, representing an essential feature of seeded FELs. These results are comforted by ELEGANT and GENESIS simulations.