Coupling between conduction and near-field radiative heat transfer in tip–plane geometry

We analyze the coupling between conduction and radiative heat transfer in the near-field regime between two coaxial cylinders separated by a vacuum gap. By solving the heat transport equation in the steady-state regime between metals or polar materials, we highlight a flux saturation mechanism for the radiative transfer even without a non-local effect. In the case of polar materials, this saturation occurs in the separation distances in the range of 1–10 nm, which can be experimentally explored.