Shmeleva L. Theoretical investigation of the process of a solid surface destruction by high-amplitude pulse

In this thesis, the problem of interaction of intense pulsed laser radiation with a solid surface is formulated on the basis of a continuum mechanics equations set. The distinctive feature of this problem is that the rupture boundary simultaneously is an interphase boundary between solid and gas. All boundary conditions, namely the condition of a mass flux balance, impulse flow balance and energy flow balance are formulated more generally. A unified methodical approach is designed to the solution of all problems arising when modeling the operation of destroying and not destroying handling surfaces by intense streams of energy. In a thesis the generalized theoretical model which describes the process of a crater formation on the surface of the substance under powerful radiation pulses is constructed. We have formulated the system of nonlinear differential equations which are characterized, in the main, by gas parameters and described the dynamics of a crater formation and dynamics of a near-surface pressure. This system in general determines the process of a crater formation on the surface of the substance. The influence of the parameter responsible for the gas-radiation interaction on pressure is analyzed. Analyzing the dependence of pressure on the pulse length, we showed that an enlargement of a plasma plume has a great influence on pressure dynamics.In the thesis the general solution of temperature dynamics of a substance surface is obtained. The threshold values as to the intensity and length of a pulse depending on characteristics of the irradiated material, and first of all on an absorptivity of irradiated materials, are also examined.