Strong Near-Field Enhancement of Radiative Heat Transfer between Metallic Surfaces

Abstract

Near-field heat transfer across a gap between plane-parallel tungsten layers in vacuo was studied experimentally with the temperature of the cold sample near 5 K and the temperature of the hot sample in the range 10-40 K as a function of the gap size d. At gaps smaller than one-third of the peak wavelength λ(m) given by Wien's displacement law, the near-field effect was observed. In comparison with blackbody radiation, hundred times higher values of heat flux were achieved at d≈1 μm. Heat flux normalized to the radiative power transferred between black surfaces showed scaling (λ(m)/d)(n), where n≈2.6. This Letter describes the results of experiment and a comparison with present theory over 4 orders of magnitude of heat flux.

Nanoscale Thermal Transfer – An Invitation to Fluctuation Electrodynamics

“…Experiments in a planar geometry, closer to theorists' favourite ( Fig. 1), have been reported in [28][29][30]. Further enhancement of heat exchange and its spatial modulation were observed with coated or 'island-decorated' samples [31,32].…”

Near-Field Heat Transfer between Multilayer Hyperbolic Metamaterials

“…It is well known that in this distance regime the radiative heat flux can be much larger than that of a blackbody due to the extra-contribution of evanescent waves such as surface phonon polaritons [33][34][35][36][37], for instance. This super-Planckian effect has been measured by many different experiments using different geometries and materials [38][39][40][41][42][43][44][45][46][47][48][49][50], in the past 10 years. So far, there is only one experiment that has measured the heat flux of an HM [27], although HM seem to have quite interesting features for near-field thermal radiation.…”

Near-Field Radiative Heat Transfer under Temperature Gradients and Conductive Transfer

“…plasmons in metals or phonon-polaritons in dielectrics, such that heat is primiarily mediated by collective electronic-photonic excitations propagating at material interfaces. Many experiments have since been performed -primarily in planar or nearly planar geometries, demonstrating very good agreement with theoretical predictions [7][8][9][10][11][12][13][14][15][16][17]. More recently, however, experiments have begun to explore nano-metric gaps, where additional mechanisms (including phonon-and electron-mediated transfer) are expected to also contribute and have demonstrated unexpected behaviours, with either a reduction or an enahncement of the flux [18][19][20].…”