Ion Acceleration—Target Normal Sheath Acceleration

Abstract

Energetic ions have been observed since the very first laser-plasma experiments. Their origin was found to be the charge separation of electrons heated by the laser, which transfers energy to the ions accelerated in the field. The advent of ultra-intense lasers with pulse lengths in the femtosecond regime resulted in the discovery of very energetic ions with characteristics quite different from those driven by long-pulse lasers. Discovered in the late 1990s, these ion beams have become the focus of intense research worldwide, because
of their unique properties and high particle numbers. Based on their nonisotropic, beam-like behaviour, which is always perpendicular to the emitting surface, the acceleration mechanism is called target normal sheath acceleration (TNSA).We address the physics of the mechanism and its dependence on laser and target parameters. Techniques to explore and diagnose the beams, to make them useful for applications, are also addressed.