Ablation processes induced by UV lasers in metals and ceramics

The interaction in air of high intensity excimer lasers (KrF) with metals (Aluminum and aluminum alloys) and ceramics (Al 2 O 3 , ZrO 2 , AlN, SiC) has been investigated. Results concern the dynamics of the generated plasma and include the visualization of the luminous plasma front and the developed shock waves by means of an ICCD camera. At the same time, a shadowgraphy optical device has allowed to observe simultaneously the formation and expansion of plasma and shock wave fronts propagating into the surrounding gas during and after the irradiation pulse (20 ns). Complex structures inside the plasma plume have been observed inducing turbulence phenomena after irradiation that could be detrimental for high repetition rates and need further study. From a theoretical point of view, numerical simulations of the described irradiation experiments have been attempted trying to predict the observed plasma dynamics and, at the same time, to provide a macroscopic estimate of the mechanical transformations induced in the treated material. A 1D thermofluiddynamic code with detailed atomic and EOS parameters has been used for the simulation of the plasma dynamics and a full 3D finite element code provided with temperature dependent material data has been used for the macroscopic assessment.