Evaporation of metals by a high-energy-density source

The authors present a theoretical model describing the evaporation and expansion of vapours from metal surfaces subject to high energy density. The model links the surface temperature of the metal with the evaporation rate and the hydrodynamic parameters of the vapour near the surface. These parameters serve as boundary values for the hydrodynamic equations describing the gas flow, which are solved by a 1-D Lagrangian simulation code. A criterion for the transition from hydrodynamic flow to molecular flow far from the metal is presented, with the aid of which they predict the vapour flux and velocity distribution as a function of the surface temperature. Good agreement between their predictions and empirical results is found.