抄録
Recently, the need for lunar exploration has increased as the first step toward future Mars exploration, and the construction of a lunar base is the key to permanent lunar exploration. In this study, we focused on alumina, which is abundant in lunar regolith, reduced to aluminum using laser diode ablation, and collected it. We aimed to improve the reduction ratio using hydrogen as a reductant and preheating the alumina before the laser irradiation. In this study, the laser intensity was 1.3 GW/m2, the wavelength was 940 nm, the ambient pressure was 100 kPa, and the hydrogen ratio was varied from 0-100% using a mixture of hydrogen and argon gases. Preheating was conducted up to 1300 K. The plume temperature estimated from the emission spectra increased up to 500 K by preheating, which corresponds to the increase in the reduction from 30 % to 63%, assuming chemical equilibrium. On the other hand, the temperature decreased with increasing hydrogen ratio due to the higher specific heat of hydrogen than argon. In the collection experiments, the preheating increased the adhesion on the collection plate by up to a factor of three. As a result of EDX analysis, the O/Al ratio on the collection plate decreased with preheating and did not change with the increase in hydrogen ratio.
https://ror.org/01w6wtk13 
