Generation of Energetic Particles in Intense Laser Matter Interaction*

The acceleration of high energy ion beams up to several tens of MeV per nucleon following the interaction of an ultra-short (t \textless 50 fs), intense (I$\lambda^{\mathrm{2}}$ \textgreater 10$^{\mathrm{18}}$ W.cm$^{\mathrm{-2}}$.$\mu $m$^{\mathrm{-2}})$ laser pulse with solid targets, is one of the burgeoning fields of research in the last few years. Mechanisms leading to forward-accelerated, high quality ion beams, operating at currently accessible laser intensities (up to 10$^{\mathrm{21}}$ W/cm2) in laser-matter interactions, are mainly associated with large electric fields set up at the target rear interface by the laser-accelerated electrons leaving the target. In this paper, we present our recent experimental results on MeV ion generation by mildly relativistic (10$^{\mathrm{19\thinspace }}$W/cm$^{\mathrm{-2}})$ short-pulse (45 fs) laser interaction with foil targets of varying thicknesses, structured / uniform targets (e.g. nano structures on thin metallic foils, sandwich targets). Spectral modification / bunching, and divergence from structured targets will be discussed.