Calculation of the effective emissivity of blackbodies made of alumina

Abstract

Blackbodies are sources of temperature radiation that are used for calibration of radiation thermometers. Their effective emissivity should be close to the value of 1 to approximate an ideal Planckian radiator. Their effective emissivity depends on the geometry of their cavity and the used material. It can be estimated by measurements, but often it is calculated by numerical methods. For typical graphite blackbodies, it was shown in the past that high effective emissivities better than 0.999 can be reached. In this paper, calculations of the effective emissivity of a alumina blackbody are presented. Alumina is a new material for blackbodies, with different radiation properties. Using two calculation methods (integrative cavity method and Monte Carlo method), the effective cavity emissivity for blank and coated alumina is estimated. It is shown that effective spectral emissivities up to 0.999 87 can be reached.

Calculation of Effective Emissivity of Isothermal Diffuse Cylindrical-inner-cone Cavity using Polynomial Interpolation Technique

“…Mathematically, the calculation of effective emissivity of blackbody cavity is mostly based on two methods. The first of them is the Integrative Cavity Method (ICM) that describes analytically the radiation exchange between surfaces inside a cavity [2], and the latter is a stochastic method that is also called the Monte-Carlo Method (MCM) using ray tracing algorithm [1][2][3]. The effective emissivity of a cavity depends on its geometry and used materials [1,4].…”