Bulg. J. Phys. vol.33 no.s3 (2006), pp. 111-116



Modelling of Material Removal and Plasma Plume Formation Induced by High-Intensity Laser Beam Pulses

R. Rozman, E. Govekar, I. Grabec
Faculty of Mechanical Engineering, University of Ljubljana, SI-1000 Ljubljana, Slovenia
Abstract. In this article, a mathematical model of material removal and plasma plume formation induced by high intensity laser beam pulses is presented. The model includes the basic thermal phenomena caused by laser beam material interaction: heating, melting, evaporation, ionization of evaporated material and plasma plume formation. An important parameter of this process is the absorption coefficient of the plasma, which is described by three different mechanisms of absorption. These mechanisms are: the inverse bremsstrahlung process, photoionization process and absorption process of light induced by small, condensed clusters. Based on the model, numerical solutions are given for KrF laser beam irradiation (wavelength of 248 nm) impinging on a nickel substrate. In the model, laser pulses with duration 50 ns and fluence range from 2.5 to 10.5 J/cm2 are considered. Results of the proposed model show that the portion of absorbed laser beam energy in the plasma plume increases with the increase of laser beam fluence. The acquired results of our model are compared with experimental example from the literature [1].

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