Experimental Studies on Thermal Oxidation and Laser Ignition Properties of Al-Mg-Li Powders

Powder ramjets are a kind of vehicle propulsion system with high specific impulse and efficiency. They provide significant benefits in terms of extended propulsion and thrust adjustment. The pursuit of a highly reactive fuel appropriate for powder ramjets is likely to stimulate advancements in innovative propulsion systems, which are crucial for deep space exploration and long-term space missions. This work presents experimental studies on the thermal oxidation and laser ignition performance of aluminum-magnesium-lithium powders at atmospheric pressure. TG-DSC curves of powders in three heating rates were obtained. The ignition processes and ignition delay times were recorded by a CO₂ laser ignition experiment system at a laser power of 10~60 W. The results show that at a lower heating rate of 10 K/min, the powder's thermal hysteresis is less, and the powder energy released in stage I is more concentrated. However, the degree of heat release concentration approached a similar level at heating rates of 30 K and 50 K. The ignition delay time decreased as the laser flux density increased. When the laser flux density exceeds 80 W/cm², the effect of laser power on the ignition delay time decreases. At atmospheric pressure, the mathematical relationship between ignition delay time and laser flux density is given. Finally, the powder ignition processes at different laser powers are represented graphically.