Analysis of the Dynamics of Laser Ablation of Polymers

The change in the main power parameters of poly(methyl methacrylate) ablation by continuous-wave CO₂ laser radiation has been studied. Measurements of the complex parameter “target weight + recoil force of ablation flow” were carried out using a force meter with computer data recording having a time resolution of 126.5 ms. Experimental data for the initial interval of 0–2 s were approximated by a model function, the processing of which made it possible to identify changes in the target weight and the recoil force of the ablation flow during irradiation. For the moment the ablation rate reaches a stationary regime, the energy efficiency of the process in a low-thrust jet engine was determined to be C_m = 115 μN/W, which decreases over time of laser irradiation due to the formation of a crater with a concave surface and an increase in gas pressure in the ablation chamber. It is noted that the type of ablation curve and, accordingly, an approximating function for the initial stage of ablation are individual for each polymer and laser beam parameters.