A mathematical model is proposed to describe laser ablation of metals in vacuum under the action of nanosecond laser pulses of moderate intensity taking into account the processes of cluster formation and decay in the vapor cloud. To describe the laser radiation absorption and metal heating, the thermal model based on the unsteady one-dimensional heat equation with a volume heat source is used, and the method of statistical modelling is employed for modelling vapor expansion and the processes of cluster formation. The efficiency of the proposed complex model is considered by the example of pulsed laser ablation of a niobium target.
T.V. Ershova2, V.F. Kosarev1, and D.S. Mikhatulin2 1Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia 2Institute of High Temperatures RAS, Moscow, Russia
Pages: 537-547
This publication is a continuation of works devoted to problems that arise in heterogeneous technologies. The matter of parameters that define the transition from surface erosion to particle spraying onto the surface is addressed. In particular, we experimentally examine the influence of temperature of the supersonic heterogeneous flow (carrier-gas temperature and particle temperature) interacting with the streamlined obstacle on the occurrence probability of either surface damage or particle spraying.
The temperature mode of a wall was studied experimentally for sub- and supercritical pressures of water in tubes with turbulence stimulators; these data were compared with similar results obtained for a smooth tube. An increase in heat transfer inside a turbulizing tube was revealed for a single- and two-phase water flows. Correlation dependencies for determination of heat transfer coefficient in a single-phase flow inside a tube with turbulence stimulators were obtained.
A mathematical model is presented for unsteady conjugate convective-conductive heat transfer in a closed volume with local sources of heat release under the conditions of a convective-radiation heat exchange on one of external faces of the solution region. The thermogravitation convection regime was analysed for moderate Grashof numbers. The typical temperature and velocity fields were obtained, and the fields of desired quantities were compared for the planar and three-dimensional models in one of the typical sections of the solution region.
The density of aqueous solutions of lithium bromide was studied by the monochromatic gamma-ray attenuation method at the saturation line from the liquidus temperature of up to 250
New generalized formulas for calculation of thermal conductivity of aqueous solutions of binary and multicomponent inorganic substances under high values of state parameters were derived. New values of thermal conductivity were calculated for aqueous solutions of salts within the ranges of temperatures of 293- 473 K, concentrations of 0- 25 mass % and pressures
The experimental setup is described and results are presented for measuring average boiling-up lag time for superheated n-hexane mixed with solid structures (activated coal, cellulose, silica gel) as function of temperature under atmospheric pressure. The
The results of computing a stationary arc with annular attachment on the butt end of a solid cylindrical cathode are presented. The influence of the discharge external parameters on the characteristics of arc plasma and the anode thermal state are considered.
