Effects of Nano Carbon Dopants on Laser Ablation Propulsion Performance of GAP.

The energetic polymer polyazide glycidyl ether (GAP) is used as the target of a laser ablation micro thruster in the experiment. The specific impulse, momentum coupling coefficient and ablation efficiency of the laser ablated GAP with different concentrations of carbon nanoparticles doping and target thicknesses are measured and the plumes are observed. The mechanism of the carbon nanoparticles doping to improve the propelling performance of the laser ablative polymer target is analyzed and the suitable method of the carbon nanoparticles doping is investigated. Experimental results show that the laser absorption of the polymer is greatly enhanced after doped with the carbon nanoparticles, but the laser ablation propelling performance does not increase obviously with the increase of the doping concentration. The high temperature local hotspots formed by the carbon nanoparticles after absorbing laser energy promote the release of the chemical energy in the polymer, which is the main reason for the improvement of the propulsion performance. The ablation depth of GAP decreases after doping the carbon nanoparticles, which shows the surface absorption characteristic similar to the metal target. With the increase of the target thicknesses, the mass of the incomplete ablative materials increases, and the utilization ratio of the target material is greatly reduced, which leads to the degradation of the polymer propulsion performance. The optimal ablation efficiency of GAP with 3% carbon concentrations in 54 p,m exceeds 250%, which is suitable for a laser ablation micro-thruster. [ABSTRACT FROM AUTHOR]