Generation and interactions of energetic tin ions

Abstract

I investigated the processes taking place in extreme ultraviolet (EUV) light sources. Light of these light sources is not visible for the human eye, but has various scientific and industrial applications. The light is created in a laser-produced plasma, from which also particles (ions) originate which can interact with the source environment (e.g. the machines in which the light is used). The plasma itself and the interaction with the surroundings is never systematically studied, as these plasmas do not appear in nature. The formation and expansion of the plasma is studied with laser ablation experiments, in which also the ion yield and energies are recorded. This helps to find better laser settings which leads to less ions while it does not diminish the desired EUV light. We discovered that the plasma expansion can be predicted by relatively simple models. After establishing the ion energies, I investigated the interaction with solid targets. We look at the scattering (‘reflection’) of incoming ions by the surface, and compare these distributions with the results of various simulation packages. The interaction takes place mainly at and just under the surface in the examined energy range, what is well-predicted by the simulation packages. The interaction with the topmost surface layer is not properly simulated. More elaborate simulation methods are apparently necessary to predict this interaction