Longitudinal laser ion acceleration in low density targets: experimental optimization on the Titan laser facility and numerical investigation of the ultra-high intensity limit

摘要: Recent theoretical and experimental studies suggest the possibility of enhancing efficiency ease laser acceleration protons ions using underdense or near critical plasmas through electrostatic shocks. Very promising results were recently obtained in this regime. In these experiments, a first ns pulse was focused on thin target to explode it second with high intensity exploded foil. The delay between two lasers allowed control density gradient seen by pulse. transition various ion regimes depending length studied. With energy few Joules, energies close TNSA accelerated for foils configurations. regime (~180 J), significantly higher than ones when exploding foil while keeping good beam quality. These demonstrate that low-density targets are candidates an efficient proton source can be optimized choosing appropriate plasma conditions. New experiments also performed gas jets. Scaling shock low ultra intensities is challenge as radiation losses electron positron pair production change optimization process. Using large-scale Particle-In-Cell simulations, which intense beams relativistic produced investigated.