Decay Kinetics of Thermal Radiation Emitted by Surface Layers of Carbon Materials under Pulsed Laser Excitation

Abstract

The decay of thermal radiation emitted by surface layers of carbon materials excited by pulses of a Q-switched neodymium laser is investigated experimentally and theoretically. It is discovered that the decay curves can be approximated with satisfactory accuracy by a sum of two exponential components with decay times of about 10 and 100 ns. Changes in the decay curves under sample irradiation by a sequence of laser pulses can be interpreted as being the result of redistribution of intensities of these two components. Based on the results of computer simulation, the conclusion is drawn that the glow-decay time is determined by the ratio of the penetration depth of the laser radiation and the thermal-diffusion length, which creates an opportunity to determine the coefficient of temperature conductivity in a thin surface layer of the studied material at high temperatures (thousands of Kelvins).