Simulation of nanoscale particles elaboration in laser-produced erosive flow

Synthesis of nanoscale particles as a result of vapor condensation under la ser vaporisation of materials into high-pressure surrounding atmosphere has been studied. A 2D-hydrodynamic model is developed for a simulation of nan oscale particles formation in a laser-produced erosive flow propagating fro m the irradiated surface into the ambient gas. The analysis is based on a c ombined solution of the set of hydrodynamic equations describing the erosiv e flow and equations of nonequilibrium kinetics of particles nucleation and condensation growth. The detailed structure of the erosive jet is studied. It is shown that nucleation and condensation fronts are separated in space and are formed between the erosive vapor-gas flow and cold ambient gas. Th e model predicts bimodal particle-size distribution function. The particle size is shown to be independent on the evaporation rate and to increase wit h the laser beam radius and the ambient gas pressure. (C) 2000 Elsevier Sci ence B.V. All lights reserved.