Switched Emissivity Changes via Electrostatic Attraction

This Phase I SBIR proposal presents a very simple and practical approach to control the radiation from a surface. The method and prototype product developed as part of this Phase I proposal can replace louvers and provide improved performance with significantly reduced complexity and weight.The approach, which only works in a space environment and with a cold background, is based on the fact that the radiation from a high emissivity samples will be maximum when that surface is in intimate (good thermal) contact with a higher temperature surface, and is near or at that temperature. Alternately, when this thermal contact is missing, the radiation to a cold environment will lower its temperature and the radiation from this cover (which can be viewed as the total system emissivity) system will approach that of the lower emissivity, high temperature surface. Calculations indicate that an effective emissivity change from .05 to 1 can be obtained when an electrostatic attraction is used to insure this intimate contact. Preliminary results of this system, using a thermal imager, indicate that the basic concept is viable, with measured changes in the apparent emissivity, from .38 to .95. Fabricating a practical coating requires detailed system design but does not require any technical breakthroughs.