<title>Laser plasma of poly (methyl methacrylate) in air: modeling and experiment</title>

Abstract

Experimental and theoretical studies on laser ablation of polymers (PMMA, polyimide) have been performed in a wide range of CO2-laser fluences. Evolution of polymer laser plume in air has been investigated with simultaneous registration of radiation spectra of the ablation products, spatial dynamics of flare, and temporal behavior of emission on separate spectral lines. It has been found that spectral lines have intensity peak after laser pulse termination while emission spectra are similar to those of organic material combusting. The results confirm that combustion of the laser-vaporized polymers occurs in the plume. A thermo-chemical model of heating and ablation of organic polymers by CO2 laser pulses has been developed which takes into account attenuation of radiation in laser plasmas and chemical processes leading to heating the plume of the ablation products. Temperature evolution in the irradiated sample, ablation dynamics, and laser beam attenuation are analyzed. The modeling results are compared with the experimental data on high-speed imaging of the plume. The effect of the formation of a plasma pipe is revealed under polymer ablation in air under normal conditions.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.