Molecular dynamics simulations of cluster distribution from femtosecond laser ablation in aluminum

Femtosecond laser ablation and plume evolution of aluminum is investigated for various inhomogeneous laser pulses. For the simulations of the atoms the molecular dynamics code IMD is used. The ablated gas-phase is scanned by a cluster algorithm (DBSCAN), from which we gain a cluster size distribution of the ablated material. Per single pulse, only a small portion of the total volume evaporates into the gas phase. Therefore-to have reasonable statistics-we have to deal with huge samples (6x10(7) atoms). The ablation threshold is determined by comparing the depth of the holes to the applied fluence. Angular and velocity distributions of the plume are compared to experiments.