In this work, the dynamic heat rejection of a VO₂-based nanophotonic variable-emittance coating is demonstrated in a cryothermal vacuum experiment that simulates a cold space environment. The fabricated coating displays a significant augmentation in radiated heat flux, from 136 W/m² at the onset of the VO₂ insulator-to-metal phase transition to 444 W/m² at the end, which is in excellent agreement with theoretical modeling. Additionally, the temperature stability of both VO₂ thin films and the fabricated nanophotonic emitter are assessed for cryogenic temperatures (down to −196 °C) and high temperatures (up to 450 °C). The VO₂ thin film shows little change in transmittance from cryogenic temperatures up to temperatures of 200 °C. The variable-emittance coating likewise shows no change in behavior at cryogenic temperatures, while the emittance remains stable up to 200 °C. The partial heating/cooling hysteresis behavior is also investigated for VO₂ thin films on silicon and the variable-emittance coating, where a theoretical model quantifying the hysteresis effect is developed for both. The substantial increase in heat rejection upon VO₂ phase transition at higher temperatures indicates great promise for the nanophotonic variable-emittance coating to be used for spacecraft thermal control with excellent temperature stability and resistance to thermal cycling.

在这项工作中，基于VO ₂的纳米光子可变发射率涂层的动态热排斥在模拟冷空间环境的低温真空实验中得到了证明。制造的涂层显示出辐射热通量的显着增加，从VO ₂绝缘体到金属相变开始时的136 W/m ²到结束时的 444 W/m ²，这与理论模型非常吻合. 此外，还针对低温（低至 -196 °C）和高温（高达 450 °C）评估了 VO ₂薄膜和制造的纳米光子发射器的温度稳定性。VO ₂从低温到 200 °C 的温度，薄膜的透射率几乎没有变化。可变发射率涂层同样在低温下没有表现出任何变化，而发射率在高达 200 °C 时仍保持稳定。还研究了硅上VO ₂薄膜和可变发射率涂层的部分加热/冷却滞后行为，其中开发了量化滞后效应的理论模型。在更高温度下VO ₂相变时热损耗的显着增加表明，纳米光子可变发射涂层有望用于航天器热控制，具有出色的温度稳定性和抗热循环性。