Summary of the Working Group 2: Ion beams from plasmas

Since the laser-produced ion beams have the ability to produce a large number of particles in a single bunch, significant effort has been made by various research groups in trying to increase the energy of those laser-produced ion beams. To tackle this, several schemes have been proposed, beyond the now widely used target normal sheath acceleration (TNSA) which relies on surface electrostatic acceleration of ions mediated by laser-heated electrons. The scheme proposed by Silva and co-workers uses low-density targets in which the laser penetrates and induces a collisionless shockwave. Provided that the traveling shock is of high velocity, it can reflect ions in the target and accelerate them to energies higher than those attained in TNSA with similar laser parameters. Radiation Pressure Acceleration (RPA) and Break-Out Afterburner (BOA) are two other proposed schemes, which takes advantage of the enhanced capability of ultra-intense lasers to allow transiting from standard TNSA acceleration to bulk acceleration, leading to higher ion energies.