Dynamics of formation of the liquid-drop phase of laser erosion jets near the surfaces of metal targets

An investigation was made of laser erosion jets formed at 0.1 — 1.5 mm above the surfaces of Pb, Co, Ni, Sn, and Zn targets. A neodymium laser emitting rectangular pulses of 400 μs duration and of energy up to 400 J was used. The diameters, as well as the number density and volume fraction of the metal particles present in the jet, were measured. An analysis of the results showed that the metal liquid drops broke up near the surface and experienced additional evaporation because of their motion opposite to the laser beam.