Ultra-high-brightness and tuneable attosecond-long electron beams with the laser wake field acceleration

Ultra-low emittance and length-tuneable electron beams can be obtained with the Laser Wake Field Acceleration (LWFA) by employing advanced ionization injection techniques, such as the Two-Color and the Resonant Multi-Pulse Ionization injection (ReMPI) schemes. There, a tightly focused, short wavelength (ionization) pulse extracts electrons from a selected inner shell of a dopant, allowing them to be longitudinally compressed and trapped in the wakefield excited by a different (driver) pulse. In this work we demonstrate, by means of analytical results and Particle In Cell simulations, that 340 as long electron beams with 2.3 GeV energy, 6.1 pC charge, 0.15 % projected energy spread, 60 nm normalised emittance, and projected 6D-Brightness in excess of [Formula: see text] can be generated with a  200 TW Ti:Sa laser system. The beam slice analysis reveals its potentialities for driving a few-spikes attosecond X-ray Free Electron Laser. Furthermore, the ultra-high projected quality, and the extreme shortness of the beams make them ideal candidates for the generation of attosecond and quasi-monochromatic γ photons beams through Thomson/Compton backscattering, or for the injection in subsequent plasma wakefield structures so as to reach TeV energies from staged LWFA.