Modeling of vapor-droplet plumes ablated from multiple spots

The study aims at modeling of plume shielding aspects of laser ablation processes with multiple laser pulses applied to multiple targets. The main obstacle with the efficient use of multiple laser pulse technologies is an attenuation of the laser irradiation by previously ablated plumes. Dynamics of plumes is described by the axisymmetric Euler equations describing a vapor-droplet ablated mixture rolling-up in the surrounding ideal gas. For multiple laser pulses, the role of absorption of laser beam by previously ablated plumes is evaluated varying a model parameter that defines the fraction of laser energy absorbed by the ablated mixture. Absorption of laser beam by plume may cause its secondary explosion that cleans the target surface and, subsequently, increases the mass ablated by the consequent pulse. Dynamics of plumes ablated from two targets with possible time delay between two laser hits is investigated as a representative case of multiple targets. Shielding of the surface between targets appears to be significant if the second pulse occurs before the first shock wave passes the second target.