Thermal heat radiation, near-field energy density and near-field radiative heat transfer of coated materials

TL;DR

This paper studies how metal coatings on materials influence thermal radiation, near-field energy density, and heat transfer, revealing the role of surface polaritons and substrate type in these phenomena.

Contribution

It provides a detailed analysis of the effects of metal coatings on near-field thermal phenomena, highlighting the impact of substrate material on energy density enhancement.

Findings

Surface polariton coupling enhances TM-mode energy density with polar substrates.

No enhancement occurs for metal substrates due to surface plasmon coupling.

Enhanced thermal energy density affects near-field radiative heat transfer between coated and uncoated bodies.

Abstract

We investigate the thermal radiation and thermal near-field energy density of a metal-coated semi-infinite body for different substrates. We show that the surface polariton coupling within the metal coating leads to an enhancement of the TM-mode part of the thermal near-field energy density when a polar substrate is used. In this case the result obtained for a free standing metal film is retrieved. In contrast, in the case of a metal substrate there is no enhancement in the TM-mode part, as can also be explained within the framework of surface plasmon coupling within the coating. Finally, we discuss the influence of the enhanced thermal energy density on the near-field radiative heat transfer between a simple semi-infinite and a coated semi-infinite body for different material combinations.