engleski

Transformation of circular into triangular craters as a function of parameters in a train of laser pulses

In the pulsed laser-material interaction with the pulse-repetition rate, nu, in the KHz range, and the scan velocity v approximate to 25.4-127 mm/s (1-5 ''/s), the morphology of the laser trace changes drastically. The trace morphology arises from few simultaneous processes: material vaporization and crater formation with surface hydrodynamic flow. Depending on nu and v, the crater form changes from circular to triangular, passing through a generation of coherent hydrodynamic and chaotic structures finishing with pairing or merging of three vortices to form a triangular one ; the laser trace changes from the discontinuous to continuous. The phenomena observed are important from the theoretical aspect for the study of interaction of 2, 3 or more vortices on a short time scale, and the applied aspect is important for deep laser scribing and surface modification uses.

surface breakdown

nije evidentirano