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A study was made of the dynamics of crater growth when a millisecond light pulse with a complex temporal profile interacted with the surface of a transparent insulator. The effective growth of a crater was found to last no more than 100 microsecond(s) and it consisted of two stages. In the first stage the area of the damage region increased while its depth remained practically constant, whereas in the second stage the crater growth was three-dimensional. The increasing use of laser treatment of materials is responsible for the growing interest in the processes resulting from the interaction of high-power light pulses with the surface of a solid. Such investigations are essential for the selection of the effective technological regimes and for the development of new monitoring and diagnostic methods; moreover, such investigations provide results of purely scientific interest. The phenomena that occur in a plasma cloud formed at the surface of a target and in the bulk of an irradiated sample have been investigated thoroughly. On the other hand, much less information is available on the processes that occur on the surface of a solid, including primary (and, at first sight, trivial) phenomena as the formation of a crater and an inelastically deformed zone. The data are particularly scarce on the interaction of solids with relatively long (at least 1 microsecond(s) ) light pulses which have complex temporal profiles (these are the pulses typically emitted by solid-state laser operating under free-running conditions). The dynamics of such surface processes under the action of a light flux has been practically ignored in the case when the solid is not a metal but a transparent insulator. However, any optical component used in experiments involving high- power laser radiation is in fact a sample of this kind investigate the dynamics of crater growth and of changes in the density of an inelastically deformed material, on the surface of a transparent insulator when it interacts with a millisecond light pulse that has a complex temporal profile.
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