Microwave permittivity and permeability measurements on lunar simulants at low temperatures

Lunar simulants are used to approximate the behavior of the lunar regolith. This work focuses on materials responses relevant for microwave heating to inform in-situ resource utilization of lunar regolith for landing pads and building infrastructure. Microwave dielectric permittivity and magnetic permeability measurements have been made for the first time on several new highland lunar simulants (NU-LHT-4M, NUW-LHT-5M and CSM-LHT-1G). One mare lunar simulant (JSC-1A) is included in this work. We present these measurements in the low temperature range -185°C to 250°C and in the frequency range 50 MHz to 3 GHz. The dominant minerals in the simulants are the minerals bytownite, ortho- and clino-pyroxenes, olivine, and glass. Less complex rock feedstocks for highland simulants, anorthosite and pyroxenite, were also measured separately. The dielectric measurements were performed on samples having different densities. To more accurately compare the magnitude of the real permittivity measurements, a normalization expression was developed. Differences in the dielectric responses were noted, however all simulants were weak microwave absorbers at the low temperatures. This data assists with planning for a hybrid approach to microwave sintering at the lunar south pole.

月球模拟物（Lunar simulant）用于模拟月球风化层（lunar regolith）的物理特性。本研究聚焦于与微波加热相关的材料响应，旨在为月球风化层的原位资源利用（in-situ resource utilization）提供指导，以支撑月球着陆垫与建筑基础设施的建设。本研究首次针对多款新型高地型月球模拟物（NU-LHT-4M、NUW-LHT-5M及CSM-LHT-1G）开展了微波介电常数（dielectric permittivity）与磁导率（magnetic permeability）测量，同时纳入了一款月海型月球模拟物JSC-1A。本次测量覆盖的温度区间为-185℃至250℃，频率区间为50 MHz至3 GHz。该批模拟物的主要矿物成分为培长石（bytownite）、正辉石（orthopyroxene）、单斜辉石（clinoproxene）、橄榄石及玻璃相；针对高地型模拟物所用的成分更简化的岩石原料——斜长岩（anorthosite）与辉石岩（pyroxenite），本研究也单独开展了测量。本次介电测量的样品具备不同的密度水平。为更精准地对比实部介电常数的测量结果，本研究构建了归一化表达式。研究观察到不同模拟物的介电响应存在差异，但所有模拟物在低温区间均为弱微波吸收体。本数据集可为月球南极区域微波烧结混合工艺的规划工作提供数据支撑。