High-speed imaging of plasma plume induced by pulse laser ablation

Abstract

A new concept of pulse laser ablation target were proposed. The idea is two-fold; that is, the target material to be ablated is a very thin layer deposited on a surface of some substrate material. As the substrate material, we will choose a transparent material like polymer or glass. Through the transparent material, a pulse laser beam is focused onto the thin film layer from rear side. In this way, we have tried to produce high energy particle beam without slow particles and droplets. Behavior of plume induced by the ablation of thin carbon film of 200 nm deposited on a polymethylmethacrylate (PMMA) substrate has been examined. Thin film target is found to achieve high energy density states by absorbing the pulse laser energy. An Nd:YAG laser of infrared wavelength is used in this study due to the efficient absorption of energy by the ablated plasma plume. Ablation emission was observed by the high-speed streak camera. Plume is shown to be induced at the carbon fllm surface and also at the opposite PMMA surface. Several velocity groups are recognized in the plume. Stress waves in PMMA plate placed close to the thin film target was observed by the pulse laser shadowgraphy.