Abstract: Some possible qualitative models of nonstationary hydrodynamical phenomena in the melt surrounding the 'key-hole' in processes of laser beam or hole punching are presented. Different mechanisms of excitation of such nonstationarities are discussed: thermocapillary, evaporative and 'wind' instabilities of the surface of the me a 'shelf' instability of melt layers subjected to the action of intense laser irradiation. Estimations of the laser beam intensity value I and processing velocity v, representing the limits of different mechanisms of instabilities, are presented. The ranges of these two parameters are: I equals 10$+4$/ - 10$+7$/ W/cm$+2$/; v equals 10$+$MIN@1$/ - 10$+2$/ cm/s. These estimations give some preliminary ideas concerning the choice of (I,v) range, which enables it to provide the stability and quality of deep penetration laser materials processing. !26
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机译：摘要：提出了一些可能的定性模型，该模型在激光束或打孔过程中围绕“关键孔”的熔体中出现了不稳定的水动力现象。讨论了这种非平稳性的不同激发机理：熔体表面的热毛细管，蒸发和“风”不稳定性;经受强激光辐照作用的熔体层的“层架”不稳定性。给出了代表不同不稳定性机制的极限的激光束强度值I和处理速度v的估计。这两个参数的范围是：I等于10 $ + 4 $ /-10 $ + 7 $ / W / cm $ + 2 $ /; v等于10 $ + $ MIN @ 1 $ /-10 $ + 2 $ / cm / s。这些估计给出了有关（I，v）范围选择的一些初步想法，这使其能够提供深穿透激光材料加工的稳定性和质量。 ！26
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