LASER-INDUCED OXIDATION PROCESS OF TUNGSTEN

A simple model for laser-induced oxidation of tungsten is presented. A thin metallic film under laser irradiation in an oxidizing atmosphere is considered. The stability of the diffusion-controlled growth of an oxide layer with external cooling and heat radiation is investigated in terms of nonlinear point-system dynamics. Depending on the material and input parameters the system can exhibit limit cycles. A time-modulated laser beam can suppress these oscillations depending on frequency and pulse shape. Instabilities of this kind can be sources for striations on the cutting surface in reactive laser gas cutting.