Dynamics of a laser-produced silver plume in an oxygen background gas

Abstract

The expansion of a plasma plume in a background gas is a key problem for film deposition and laser ablation studies. Combined diagnostic measurements of deposition rates and ion time-of-flight (TOF) signals have been used to study the dynamics of a laser ablation plume in an oxygen gas. This study is similar to our previous work on an argon background gas and shows essentially the same trend. At an enhanced gas pressure, the angular distribution of collected ablated atoms becomes comparatively broad, while the total collected yield decreases strongly. The total collected yield exhibits three separate regimes with increasing pressure, a vacuum-like regime, a transition regime with increasing plume broadening and splitting of the ion signal, and at the highest pressures a diffusion-like regime with a broad angular distribution. In the high pressure regime, the expansion can be described by a simple model based on diffusion from a confined plume.