Quasi-mono-energetic ion acceleration from a homogeneous composite target by an intense laser pulse

The paper presents an analytical model and particle-in-cell simulations of the quasi-mono-energetic ion acceleration by an intense laser pulse in a multispecies target and the corresponding experimental observations. Homogeneous and heterogeneous targets are considered, and it is shown that the formation of the energy spectrum proceeds in three stages: (1) the initial light ion acceleration in the sheath electric field, (2) the ion species separation followed by the electrostatic shock formation, and (3) the interaction of spatially separated ion bunches accompanied by electron cooling. The field ionization of heavy ions and interaction between the heavy and light species play an important role in the formation and preservation of the energy spectrum of light ions. The simulation results are compared with the theoretical predictions and the experiments. (c) 2006 American Institute of Physics.