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.