TEMPERATURE AND STRESS FIELDS IN SILVER DUE TO LASER PICOSECOND HEATING PULSE

Abstract

Laser short-pulse heating of metallic surfaces is involved with nonequilibrium energy transport in the region irradiated by a laser beam. In this case, the Fourier heating model fails to predict correct temperature rise in this region. Moreover, for completeness of analysis, the thermomechanical coupling needs to be incorporated in the governing equations. In the present study, electron kinetic theory approach is introduced to model the heating process and thermomechanical coupling is formulated and accommodated in the energy transport equation. Temperature and stress fields are computed numerically for silver. It is found that electron temperature well in excess of lattice site temperature occurs in the surface vicinity of the substrate material. Although lattice site temperature rise is low (~170°C), stress levels as high 3 2 10 8 Pa are computed in the region heated by a laser beam. The thermal expansion of the surface at the irradiated spot center reaches 0.5 nm after 4 ns of the heating period.