MeV proton sources for plasma dynamics investigations on PS timescales

The interaction of high-intensity laser pulses with matter releases instantaneously ultra-large currents of highly energetic electrons, leading to the generation of highly-transient, large-amplitude electric and magnetic fields. We report results of recent experiment in which such phenomena have been studied by using proton probing techniques able to provide maps of the electrostatic fields with high spatial and temporal resolution. The dynamics of ponderomotive channelling in underdense plasmas have been studied with this technique, as also the process of Debye sheath formation and MeV ion front expansion at the rear of laser-irradiated thin metallic foils.