Small Business Innovation Program, Final Report, Phase 1. Selective Thermal Radiators

摘要

The objective of this work was to determine if a 'prepared surface' could serve to tailor the radiant output of a surface within the thermodynamic limits of blackbody radiation. Experiments used ion implantation to modify the radiation and evaporation surface properties of tungsten filaments operating at about 2800 degrees K. Tungsten filaments ion implanted with carbon at low energy showed an ability to dissipate more energy than unimplanted tungsten filaments when operated in parallel prior to filament failure. Infrared reflectance measurements of a blackbody source indicated anomolous behavior, in that the reflectance and emittance of the surface appeared to be a strong function of the wavelength in the vicinity of the period. There appeared to be a concomitant shift toward longer wavelengths in the peak of the reflected blackbody radiance spectrum when a periodically structured reflector was used. These results were not conclusive of the postulates that either ultra thin filament surface coatings could modify evaporation rate or emissivity, or that a periodically structured surface could suppress long wavelength emittance.