In this seminar, the subject of superintense laser-driven ion acceleration will be reviewed [1] and some recent developments discussed. Since its surprising discovery in 2000, ion acceleration from solid targets irradiated by high-intensity pulses attracts a phenomenal amount of experimental and theoretical research worldwide. Key to this interest are the ultra-compact spatial scale of the accelerator and the properties of the laser-driven ion beams, under several aspects markedly different from those of "conventional" accelerator beams. The research conducted so far naturally leads to a number of crucial, fundamental questions which the community needs to face to obtain ground-breaking advances. In this talk, special focus will be given on the problem of the maximum ion energy achieved in the Target Normal Sheath Acceleration scenario, which is by far the most natural acceleration mechanism in most experiments. First, the development of effective analytical modeling of the TNSA will be discussed, with the aim of both gaining satisfactory interpretation and obtaining reliable scaling laws, to understand experimental data and provide realistic predictions for future system parameters. Also, some novel ideas to optimize the maximum ion energy through an active control of target properties will be presented, with particular reference to experimental and theoretical studies dealing with the fabrication of nano-engineered multilayered targets composed by a main solid foil with an ultralow-density layer on the illuminated side.

[1] A. Macchi, M. Borghesi, M. Passoni, “Ion acceleration by superintense laser pulses”, Reviews of Modern Physics, to be published.