"Since the first laser discovery in 1960 and the first Free Electron Laser (FEL) in 1977, Linac based fourth generation light sources provide intense coherent fs pulses in the X-ray range for multidisciplinary investigations of matter. In parallel, Laser Wakefield Accelerator (LWFA) by using intense laser beams interacting with cm long plasmas can now provide high quality electron beams of very sh ...