Design and Performance Evaluation of MEMS-Based Spaceborne Variable Emissivity Radiator Using Movement of Electrified Beads

A novel concept of a variable emissivity radiator was proposed and fabricated using micro electro mechanical system (MEMS) technologies. The emissivity of the radiator can be varied by moving beads electrified along the direction of an electric field. A continuous power supply is not required to sustain the desired state of the radiator to maintain a high or low emissivity state once the beads are electrified by applying a pulse voltage signal. The operational function and the thermal control performance of the fabricated radiator were investigated through experimental approaches. In addition, the theoretical maximum effective emissivity was predicted using a simple numerical model and was compared with the actual value experimentally measured by the thermal test. The temperature difference on the radiator based on the position of the electrified beads, which corresponds to the open and close modes of the radiator, was measured under vacuum condition. The feasibility of the proposed MEMS-based variable emissivity radiator was successfully demonstrated, and its effectiveness in terms of thermal control performance was evaluated through the experimental and numerical approaches.