Experimental Investigation of Liquid-propellant Laser Propulsion with a Horizontal Momentum Measuring Lever

Thrust performance of Liquid-propellant laser propulsion (LLP) is seriously influenced by factors like laser parameters, choice of propellants and ablation materials. For the purpose of studying these influences, series of impulse measuring experiments for various propellants and ablation materials were conducted. The key device is a Horizontal Momentum Measuring Lever, which covers a Cm measuring range from 103 Ns/MJ to about 1.6x104 Ns/MJ. A Nd:YAG laser was used as the laser source. From the result, it is found that laser energy density plays an important role on LLP efficiency, higher energy density leads to higher Cm and Isp. Highest Cm of about 104 Ns/MJ with the Isp of 3.57s was achieved by focusing the laser to the average energy density of 8.83x108 W/cm2. Besides of that, it is also found that when the energy density is certainly high, Cm of LLP increases stably with the increase of the propellant thickness, which gives a potential way to further improve the thrust performance in LLP.