title: Radiation characteristics of a high-emissivity cylindrical-spherical cavity with obscuration.
abstract: We have calculated, to first order, the apparent emissivity of the bounding diffuse surfaces of a high-emissivity cylindrical-spherical cavity enclosure. Our calculations indicate that to achieve emissivities close to a perfectly absorbing blackbody cavity along the bounding surfaces of the spherical enclosure, the radius of the sphere must be equal to or greater than a factor of 4 times the cylinder radius R(S) > or = 4R(C). Furthermore, to achieve emissivities approaching a blackbody cavity along the lower bounding surfaces of the cylindrical enclosure, the length of the cylinder must be a factor of 4 times greater than the radius of the cylinder L > or = 4R(C). In addition, we present the mathematical framework necessary to calculate radiant transfer within a cavity enclosure that contains obscuration. These results can be applied to the design of high-emissivity blackbody calibration cavities and to the reduction of stray light in terrestrial and spaceborne optical systems.
authors.affiliation: Innovision Directorate, National Imagery and Mapping Agency, Mail Stop DN-11, Reston, Virginia 20191, USA.
authors.forename: Steven R
authors.initials: SR
authors.lastname: Meier
authors.forename: Richard I
authors.initials: RI
authors.lastname: Joseph
authors.forename: Spiro K
authors.initials: SK
authors.lastname: Antiochos