Three-Dimensional Simulations of Ion Acceleration from a Foil Irradiated by a Short-Pulse Laser

Using 3D particle-in-cell simulations we study ion acceleration from a foil irradiated by a laser pulse at 10¹⁹ W/cm² intensity. At the front side, the laser ponderomotive force pushes electrons inwards, thus creating the electric field by charge separation, which drags the ions. At the back side of the foil, the ions are accelerated by space charge of the hot electrons exiting into vacuum, as suggested by Hatchett et al. [Phys. Plasmas 7, 2076 (2000)]. The transport of hot electrons through the overdense plasma and their exit into vacuum are strongly affected by self-generated magnetic fields. The fast ions emerge from the rear surface in cones similar to those detected by Clark et al. [Phys. Rev. Lett. 84, 670 (2000)].