Modelling of laser produced plasma and time-of-flight experiments in UV laser ablation of aluminium targets

Experimental and theoretical analysis have been performed to investigate UV laser ablation of Aluminium targets irradiated in vacuum. From lime-of-fli ght (TOF) investigation a direct characterisation of the ions kinetic energ y distribution and yield as a function of the laser fluence has been obtain ed. Moreover. the total yield of charged particles (ions and electrons) has been investigated. All the investigated plasma parameters strongly depends on the laser fluence until a roll off is reached at higher irradiance. Thi s behaviour has been analysed by discussing a laser-solid-plasma interactio n model taking into account photon absorption and ionisation mechanisms act ive in the Al plasma as well as laser produced plasma kinetics. Calculation s suggest that the observed behaviour is due to plasma kinetics and shieldi ng occurring around 1 GW cm(-2) in nanosecond pulsed laser ablation of Al t argets. (C) 1999 Elsevier Science B.V. All rights reserved.