Under critical and near-critical dense plasmas: laser-driven particle acceleration and diagnostics

High-intensity laser-based particle accelerators are becoming a real alternative to conventional radiofrequency accelerators. Higher accelerating fields in much shorter lengths give beam performances comparable to the standard RF cavity approach. Energetic ion, electron, and X-ray beams have been produced and measured at VEGA 2 laser facility (CLPU) in recent experimental campaigns. The density of the target, as well as the laser parameters fully determine the acceleration mechanisms. In this talk, a short overview of the most important acceleration schemes in under and near-critical dense plasmas is given. The most interesting optical diagnostics for plasma characterization are also discussed. Results from VEGA 2 experiment will be shown.