Production of ultrahigh-current-density ion beams by short-pulse skin-layer laser–plasma interaction

We report experimental evidence, supported by a simple theory and numerical calculations, that the skin-layer subrelativistic interaction of a short (⩽1ps) low-energy (<1J) laser pulse with a thin preplasma layer in front of a solid target can produce a collimated fast ion flux of extremely high ion current density (⩾1010A∕cm2 close to the target), comparable to those predicted for ballistically focused ion beams from relativistic laser–plasma interactions.