Mathematical modelling of pulsed laser ablated flows

Numerical modelling of non-steady state laser-ablated flows is presented. T wo simulation methods, the Monte Carlo technique and the large-particle (LP ) method are used to investigate pulsed laser evaporation for different las er fluences under vacuum. Time-evolutions of the flow parameters are relate d to the evaporated material properties and laser pulse parameters. Non-Max wellian time-of-flight (TOF) distributions are attributed to both non-stati onary surface evaporation and inter-particle interactions in the laser plum e. A radial surface temperature distribution was found to influence the plu me shape. The influences of the experimental parameters on the TOF signal a nd on the plume shape are analyzed based on the Knudsen layer - unsteady ad iabatic expansion model. The role of the evaporation yield, laser beam radi us, initial plume length, and evaporation barrier in the formation of the a ngular distribution of the ablated material are discussed. The study concen trates on a better understanding of pulsed laser deposition (PLD). (C) 2000 Elsevier Science B.V. All rights reserved.