Lunar regolith is a dielectric material which can be efficiently heated to melting temperature using microwave energy [1]. Sintered or melted regolith can then be used as feedstock to construct infrastructure on the Moon, including landing pads, roadways and habitats. A material’s real permittivity, ε’, and imaginary permittivity, ε’’, are important factors in determining the efficiency of microwave heating. For lunar regolith, these increase with temperature [2,3].

Temperature-dependent permittivity measurements made under microwave heating [3] have been found to differ notably from those made under furnace heating [2]. This suggests that the heating method influences permittivity measurements. Therefore, understanding the underlying mechanisms behind this behaviour will enable improved computational modelling and the optimisation of microwave heating processes.