The Study on the Effect of Particle Size on the Electromagnetic Heating Characteristics of Lunar Regolith Simulant

Microwave sintering of lunar soil is widely regarded as one of the most promising technological options for future in-situ resource utilization （ISRU） on the lunar surface and is critical for the construction of lunar bases and related infrastructure. This technique exploits the intrinsic microwave responsiveness of lunar soil to form solid structural components without requiring external binders or material transport from Earth. In this study, based on the theoretical background and physical processes of electromagnetic heating in lunar regolith simulant, electromagnetic reflection loss and attenuation loss were selected as the core indicators for comprehensively evaluating the electromagnetic heating characteristics of lunar regolith simulant. Using the waveguide measurement method, electromagnetic parameters of lunar regolith simulant with different particle sizes were experimentally determined in the frequency range of 2.17 to 3.3 GHz. On the basis of these measurements, quantitative calculations and systematic comparisons of electromagnetic reflection loss and attenuation loss among different particle size ranges were conducted. The results revealed a pronounced nonlinear relationship between particle size and dielectric properties of the lunar regolith simulant. Specifically, as particle size decreased, the complex permittivity and related dielectric parameters initially increased, reached an optimum value, and subsequently decreased. Notably, lunar regolith simulant within the particle size range of 120 to 230 mesh exhibited the most favorable dielectric performance, with superior energy storage and dissipation capacity in the electric field. This specific particle size range effectively reduced surface electromagnetic wave reflection while maximizing attenuation loss, thereby enhancing the absorption of electromagnetic energy within the regolith and its conversion into thermal energy. Collectively, these characteristics significantly improved the electromagnetic heating characteristics of the lunar regolith simulant, this enabling more efficient and reliable microwave sintering. This work provides valuable reference for microwave sintering of lunar soil in future lunar missions, and greatly advances the development of ISRU technologies for sustainable lunar exploration.