ACCELERATED EXPANSION OF LASER-ABLATED MATERIALS NEAR A SOLID-SURFACE

A dynamic source effect that accelerates the expansion of laser-ablate d material in the direction perpendicular to the target is demonstrate d. A self-similar theory shows that the maximum expansion velocity is proportional to c(s)/alpha, where 1 - alpha is the slope of the veloci ty profile and c(s) is the sound speed. Numerical hydrodynamic modelin g is in good agreement with the theory. A dynamic partial ionization e ffect is also studied. With these effects, alpha is reduced and the ma ximum expansion velocity is significantly increased over that found fr om conventional models.