Laser Ablation of Metals

Laser ablation is the process of removing material with very intensive, pulsed laser radiation. It is a technology which gains increasingly greater importance for drilling, eroding, welding, structuring and marking of all kinds of materials. With the advent of ultrashort picoand femtosecond pulses especially, a large number of new processing methods were developed. A deeper understanding of the ablation process itself still lacks behind. The time scales of the processes involved in laser ablation are in the range from a several hundred femtoseconds (laser pulse) through a few picoseconds (electron-lattice-relaxation time) up to many nanoseconds (extrusion of the melt, cooling of the sample). Thus molecular dynamics (MD) simulations are the method of choice to get a deeper inside into the issue. The time steps applied are of the order of a few femtoseconds; on current computer architectures a few million time steps can be simulated. Thus the whole scope of interesting phenomena can be covered with atomistic resolution. Such a detailed treatment of the time steps and particle coordinates cannot be handled on common institute workstations, neither the wall clock time nor the storage of the results. Thus for most of the computations we rely heavily on the supercomputers of the HLRS.