Characteristics of deep-penetration melting by a moving laser beam

A study is made of the problem of deep-penetration ("dagger-like") melting of a metal target by a moving laser beam. The basic equations for the description of the deformation of the surface of a material under the action of its vapor are formulated allowing for the flow of the melt. The variation of the shape of the melt surface with the velocity of a laser beam is found. The dependence of the threshold of the deep-penetration melting on the beam velocity is determined and it is shown that such melting is possible at high beam velocities.