Investigation of the preplasma characteristics produced by the interaction of a laser pulse and a thin foil/film target.

With the current state-of-the art of laser technology, the existence of amplified spontaneous emission (ASE) and prepulse can be limited but still inevitable. As the laser intensity increases, the ASE and prepulse effects become significant in interaction of the intense laser pulse and a thin foil target before the main pulse arrives. When the ASE level exceeds the ionization and damage thresholds of the target materials, formation of the preplasma on the target surface due to the ASE will lead to destruction of the thin foil target. This early interaction may be very important in ion acceleration using a high power laser and a thin foil. So far, there have not been much studies on the formation and dynamics of the preplasma. In this work, we used a small mJ-scale laser system where the laser pulse was focused on the surface of a thin foil/film (aluminium and mylar) to generate a preplasma intentionally and its characteristics was investigated by using the pump and probe method. Some detailed results will be shown in this presentation.