Product Code: PIC2008_M701

Multiscale Modeling of Ultrafast Laser-Material Interactions (Invited Paper)
Authors:
Hai-Lung Tsai, University of Missouri-Rolla; Rolla MO USA
Lan Jiang, Beijing Institute of Technology; Beijing Peoples Republic of China
Presented at PICALO 2008

This paper reports the overall picture of our ongoing efforts to establish the scientific understanding of ultrafast, non-equilibrium laser-material interactions from nanometer to milimeter and from femtosecond to microsecond through comprehensive, integrated multiscale physico-chemical modeling and experimental verification. Based on the time when collisions govern the evolution of the phenomena, modeling of ultrafast laser-material interactions is divided into three stages: 1) femtosecond pulse absorption through photon-electron interactions, including electron heating, excitation and generation; 2) electron-ion interactions, including energy transport, phase change and plasma generation; and 3) plasma expansion, shock wave propagation and radiation during plasma-environment interactions. A novel plasma model with quantum treatments was developed to account for significantly varying optical properties. The model was used to successfully predict two uncommon phenomena that were experimentally observed: 1) a flat-bottom crater shape created by a Gaussian beam and 2) repeatable nanoscale structures achieved by pulse train technology. The well known two-temperature model was improved by considering the quantum effects of different heat carriers and then was used to accurately predict the damage thresholds for metals. The ab initio molecular dynamics model is being developed to predict the plasma generation, and a continuum model is also being developed to account for the chemically reacting two-phase fluid flow of the generated plasma. Preliminary results for these ongoing modeling efforts will be reported.