Effect of Preheating Temperature of Al₂O₃ on Reduction Ratio by Laser Diode Ablation under Hydrogen Atmosphere

Today, interest in permanent lunar exploration, such as the Artemis plan, is growing in anticipation of future Mars exploration. In this case, the construction of a lunar base based on ISRU is important due to the high cost of material transportation from the earth. In this study, a 1 kW-class laser diode was used to ablate Al₂O₃, which is abundant in the lunar regolith, and reduce it to aluminum in a hydrogen atmosphere. In a previous study, the plume temperature decreased by about 400 K compared to that of the argon-filled plume due to the energy consumed by hydrogen dissociation under hydrogen-filled conditions. Therefore, we attempted to raise the plume temperature by preheating Al₂O₃ to a higher temperature even with the hydrogen atmosphere.