Large-scale structures produced on metal surfaces by multiple laser pulses

A mathematical model is constructed to describe the formation of inhomogeneous surface structures 10—50 μm in height on metal surfaces exposed to repetitive laser pulses with the following parameters: pulse duration of ~20 ns, pulse repetition rate of ~10 kHz, pulse intensity in the range 10⁷—10⁸ W cm^-2 and beam diameter from 50 to 100 μm. The model takes into account melting of the metal and melt flow over a distorted surface. The surface profile amplitude evaluated in the model agrees with experimental data.