Plasma Torch Development and Crater Growth Dynamics in the Course of Laser Processing of Materials and its Diangostics

The evolution of the plasma torch arising under the action of laser radiation on a metal specimen has been investigated by several methods. The dependence of the time form and the spectrum of acoustic vibrations on the parameters of the irradiated material and the law of increase in the crater depth has been determined. It has been found that under the action of a lser pulse of length ~20 μs on the surface of a copper specimen the growth time of the destruction zone is about 40–50 μs, which is in good agreement with the lifetime of plasma formation near the surface of the target subjected to laser-plasma processing (~50 μs). It has been shown that the use of the model of a loaded zone with moving boundaries emitting acoustic waves into an elastic medium permits solving an important practical problem — determining the law of time growth of the zone of irreversible deformations on the surface of the specimen subjected to pulsed laser plasma processing.