Vaporization of Metal Absorbing Laser Radiation

The problem of vaporization of a light-absorbing metal into vacuum is considered. It is assumed that the density of the light energy flux is not excessively large so that there is no significant absorption of light by the vapor. The expansion of the vapor thus occurs in a centered rarefaction wave. The obtained boundary conditions relate the values of the hydrodynamic variables in the rarefaction wave with the surface temperature of the metal. This is accomplished by an approximate solution of the gaskinetic problem of vapor motion within a thin film directly adjacent to the phase interface. The velocity of the vaporization front, the surface temperature of the metal, the temperature and velocity of the vapor, and the recoil momentum are calculated.