Ultra-high brightness electron beams by all-optical plasma-based injectors

We studied the generation of low emittance high current mono-energetic beams from plasma waves driven by ultra-short laser pulses, in view of achieving beam brightness of interest for FEL applications. We have studied a regime based on a LWFA plasma driving scheme on a gas jet modulated in areas of different densities with sharp density gradients. Simulations carried out using VORPAL show that, using a properly density modulated gas jet, it is possible to generate beams at energies of about 30 MeV with peak currents of 20 kA, slice transverse emittances as low as 0.3 μm and energy spread around 0.4 %. This beams break the barrier of 1018 A/(mm.mrad)2 in brightness, opening a new range of opportunities for FEL applications. An example of FELs driven by such kind of beams injected into laser undulators is shown. The system constituted by the electron beam under the effect of the e.m. undulator has been named AOFEL (for All Optical Free-Electron Laser)