Small Spacing Analysis of Radiative Transfer Between Parallel Metallic Surfaces

An attempt is made on the basis of electromagnetic theory to predict spacing effects on the radiative transfer between two closely-spaced, semi-infinite metals separated by a nonconducting dielectric. Electromagnetic energy transmission factors are derived for a general, three-medium system and their simplification for the metal-dielectric-metal system is shown. The net energy flux is calculated with these transmission factors and the estimated intensities in the metals. Numerical results are given which exhibit the effects of metal spacing, metal type, temperature level, and type of dielectric. Variations in the heat flux of several orders of magnitude are shown to exist in a system whereas the Stefan-Boltzmann relation indicates a constant flux, independent of spacing.