Particle acceleration: the laser Plasma approach

With the achievement of the chirped pulse amplification technique, laser intensities have been increased by several orders of magnitude, permitting now to reach the relativistic regime (e.g. electrons oscillate in the laser field with relativistic velocities). The interaction of such powerful lasers with underdense plasmas has allowed studies of various new phenomena. In particular, extremely high electric fields, several orders of magnitude greater than those obtained in conventional accelerators, have been measured. These high fields are able to trap plasma background electrons and accelerate them to relativistic energies. As a consequence, relativistic electron beams are now routinely being produced using lasers in the laboratory. A review of the processes involved as well as the evolution of compact laser plasma accelerators will be presented. Some already identified applications of these new particle beams with unique parameters will be also presented. (Author)