On the generation of transient capillary waves on the surface of laser irradiated targets

In carrying out vapour pressure measurements on uranium carbide using a laser surface heating technique, an apparent ring structure on the target surface has been observed. Surface temperatures from 3000-5000 K were produced by laser power profiles of 106W/cm2 and duration approximately 100μs. At these temperatures, the solid melts, forming a pool of liquid on the target surface, and the ring structure is attributed to the radial propagation of a central disturbance on this liquid surface in the form of capillary waves. It is proposed that the observed phenomena could possibly be used to measure the surface tension and viscosity of liquid metals in the temperature range 2000-5000 K. (Auth.)