Search Results

This paper describes a new approach to spacecraft thermal control based on a passive thin-film smart radiator device (SRD) that employs a variable heat-transfer/emitter structure. The SRD employs an integrated thin-film structure based on V1-x-yMxNyOn that can be applied to existing Al thermal radiators. The SRD operates passively in response to changes in the temperature of the space structure. The V1-x-yMxNyOn exhibits a metal/insulator transition with temperature, varying from an IR transmissive insulating state at lower temperatures, to a semiconducting state at higher temperatures. Dopants, M and N, are employed to tailor the thermo-optic characteristics and the transition temperature of the passive SRD. The transition temperature can be preset over a wide range from below -30°C to above 68°C using suitable dopants. A proprietary SRD structure has been developed that facilitates emissivities below 0.2 to dark space at lower temperatures to reduce heater requirements.

This paper presents experimental results regarding a new approach to smart radiator devices (SRD) employing a smart, integrated thin-film structure based on V1-x-yMxNyOn that can be applied to existing thermal blankets such as Kapton or to thermal radiators such as Al. The smart coating facilitates thermal control by dynamically modifying the thermo-optic characteristics of the underlying substrate in response to the ambient temperature and/or a control voltage. This methodology has significant advantages over competitive technologies in terms of weight, cost, structural simplicity, and integration with the space structure. The effective emissivity of the film/substrate structure can be reduced dynamically by changing the behavior of the smart coating from insulator to metallic. High quality VO2 films have been prepared using a hybrid reactive laser ablation technique.