LASER SHORT-PULSE HEATING: INFLUENCE OF LASER POWER INTENSITY ON TEMPERATURE FIELDS

Abstract

High-power-intensity and short-pulse laser heating of metallic surfaces results in thermal separation of electron and lattice subsystems. In this case, energy transport between the subsystems is governed mainly by the collisional process. Moreover, electron and lattice subsystems respond differently for different pulse intensities, despite the fact that the laser pulses have the same energy content. Consequently, in the present study, laser step-input pulse heating of gold substrate is considered and the thermal response of electron and lattice subsystems to four different intensity pulses with the same energy content is examined. The electron kinetic theory approach is introduced to model the nonequilibrium energy transport in the substrate material. It is found that electron temperature rises rapidly in the heating cycle while lattice temperature rise is gradual, which is more pronounced for laser short pulse lengths. In the cooling cycle (time after the laser pulse diminishes), electron temperature decay rate differs from the rate of lattice site temperature rise due to the specific heat ratios of electron and lattice sites.