Abstract
When high power, pulsed laser interacts with materials, a condensed plasma layer is generated above the target surface. The laser-induced plasma changes the energy coupling mechanisms between the laser beam and the target. This work investigates the radiative heat transfer process in the plasma layer generated by laser irradiation. Novel diagnostic techniques are developed to measure the transient transmission and scattering of the thin plasma layer within the duration of the laser pulse. Based on the measurements radiative heat transfer analysis is performed to evaluate the radiative properties of the plasma layer, including the optical depth, the absorption coefficient, the single scattering phase function, and the scattering size parameters. Knowledge on these radiative properties help to understand the energy transfer process during laser materials interaction. Further this work demonstrates the feasibility of using the transient scattering measurement for in-situ monitoring of the diameter of the laser ejected particles.
