Effects of vapor layer on the coupling of pulsed DF laser radiation to Al2O24

The interaction of high-power laser radiation with metals has been extensively studied, primarily in the context of 10.6 micron laser radiation. The present study is devoted to investigating the influence of an aluminum vapor layer on the transport of pulsed DF laser radiation to an Al2O24 target. When a plasma is ignited, a one-dimensional laser supported combustion (LSC) wave is formed and propagates up the laser beam and away from the surface. The LSC wave model which successfully predicts the radiative transfer 10.6 micron LSC wave plasmas, was adapted to 3.8 micron laser radiation. Here, the behavior of an aluminum vapor layer exposed to the radiation flux from an LSC wave plasma is modeled. The analysis is then combined with the LSC wave plasma model and the target thermal response model in order to predict the total interaction between the laser and the target. Results for two different representative laser pulse shapes indicate that the vapor layer impedes the transfer of energy from the LSC wave plasma.