Thick Film Analysis of Radiative Transfer Between Parallel Metallic Surfaces

The radiative transfer between two infinite parallel metallic surfaces separated by a nonconducting ideal dielectric is calculated on the basis of electromagnetic wave theory. The solution is restricted to the case of large spacing (thick film) wherein the effects of interference and radiation tunneling can be neglected. The optical properties of the metals are predicted via the anomalous skin effect theory, the Drude single electron theory and the Hagen-Rubens relation. A comparison of the predicted radiative fluxes indicates the large disparities which result from the three different specifications of the optical properties of metals. For practical applications at cryogenic temperatures, approximations are obtained for the thick film solution using the anomalous skin effect theory of the optical properties.