Temperature-dependent dielectric properties of the Korean lunar simulant and ilmenite: Lunar microwave processing potential

Abstract

There is increasing interest in the potential application of microwave sintering technology in the construction of infrastructure on the Moon. This study aimed to characterize the dielectric properties of in situ lunar materials; this information is critical for an understanding of the interaction of these materials with microwave and in the application of microwave sintering technology. Dielectric properties including the real and imaginary permittivity, dielectric loss tangent, penetration depth, and electrical conductivity of Korean Lunar Simulant (KLS-1) and ilmenite (an abundant lunar mineral) were investigated at microwave frequencies as a function of temperature. X-ray dispersion (XRD) analyses confirmed that the lattice expansion of minerals with increasing temperature was consistent with an increasing trend in permittivity. The dielectric loss tangent of ilmenite was 2–36 times higher than that of KLS-1, depending on temperature, indicating that ilmenite has greater ability to absorb microwave energy, converting it to heat. Ilmenite demonstrated rapid heating to 1000°C within a few minutes on exposure to 1 kW microwave (2.45 GHz) irradiation. This study provides important information relevant to the development of microwave technology for future lunar applications.