Accelerated expansion of laser-ablated materials near a solid surface

A dynamic source effect that accelerates the expansion of laser-ablated material in the direction perpendicular to the target is demonstrated. A self-similar theory shows that the maximum expansion velocity is proportional to csα, where 1-α is the slope of the velocity profile and cs is the sound speed. Numerical hydrodynamic modeling is in good agreement with the theory. A dynamic partial ionization effect is also studied. With these effects, α is reduced and the maximum expansion velocity is significantly increased over that found from conventional models.