A zirconia near-blackbody radiation source, 2500 K in air

A near-blackbody radiation source was designed for operating in an oxidizing atmosphere up to 2500 K. As a small zirconia furnace, the radiation source has a blackbody cavity, provided by a lateral hole formed on an yttria-stabilized zirconia tube. A good transfer radiation source should have an emissivity independent of the wavelength. This condition depends on the emissivity of the material and on the thermal characteristics of the source. The emissivity of the cavity has been calculated for different experimental conditions. The influence of temperature gradients in the cavity has been outlined. The aperture of the source, which is given by the sizes of the holes in the radiation shields, should not be too large. to avoid a large temperature gradient. even though some compensation occurs. For special applications. the aperture can be as large as 60°. The stability of the source has been studied.Paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24, 1994, Boulder, Colorado. U.S.A.