Critical fluence effects in laser propulsion

The fluence dependence of the laser ablation of selected polymers was studied within the range from 1-150 J/cm 2 . A TEA CO 2 laser operating at 10.6 μm with 300 ns main pulse length and up to 20 J pulse energy was used to ablate prepared polymer samples with single pulses of laser energy. Measurements of parameters such as the ablated mass per spot area (Δm a ), momentum coupling coefficient (C m ), specific impulse (I sp ), and internal efficiency (η i ) will be plotted as functions of fluence. Critical threshold effects observed throughout the experiments will be described in detail.