A steady-state crater formed as a result of interaction of high-power cw CO2 laser radiation with metals and liquids

It was established experimentally that the efficiency of the action of continuous laser radiation on a metal target increases steeply when the intensity reaches a certain threshold. A dagger-shaped molten region then forms on the target surface and a continuous optical discharge takes place above the surface. Formation of a laser crater under the action of the recoil pressure of a jet of vaporized matter is considered as a mechanism which can explain the deepening of the heat source. Formation of a channel in matter under the action of intense laser radiation is confirmed by the authors' experiments on liquids which also exhibit deep craters. An estimate is obtained of the depth of a laser crater in water.