The normal emittance of circular cylindrical cavities.

ABSTRACT

Analytical results, applicable both monochromatically and totally, are obtained for the normal emittance of diffusely emitting and reflecting cylindrical cavities. The analysis takes account of the size and location of the receiver which senses the radiant energy streaming from the cavity opening as well as of the cavity geometrical and surface emittance parameters. It is found that the distance of the receiver from the cavity can have an important effect on the normal emittance results, but that the size of the receiver is of secondary importance. The normal emittance exceeds the hemispherical emittance for cavities having a depth-to-radius ratio greater than unity.