Time-resolved force and ICCD imaging study of TEA CO2 laser ablation of ice and water

Time-resolved force measurements and Intensified Charge-Coupled Device (ICCD) imaging techniques were applied to the study of force generation in the laser ablation of water and ice. A transversely excited atmospheric (TEA) CO, laser operated at 10.6 mu m, 300 ns pulse width, and up to 20 J pulse energy was used to ablate water and ice held in various containers. Net imparted impulse and coupling coefficient were derived from force sensor data and relevant results will be presented for ice and water. ICCD imaging was used in conjunction with time-resolved force measurements in order to determine the dominating physical mechanism under which the thrust is produced. The effect of shock wave generation and propagation, as well as its contribution to the overall impulse imparted to the targets, was examined from the comparison of the timelines for the pertinent phenomena. The process of mass removal was investigated for each case, and specific impulse and efficiency were calculated from the data. Differences in the force-time curves for ice and water will be presented and discussed. Ballistic experiments were conducted in order to corroborate the force measurements.