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Near-Field Thermal Radiation
Published in John R. Howell, M. Pinar Mengüç, Kyle Daun, Robert Siegel, Thermal Radiation Heat Transfer, 2020
John R. Howell, M. Pinar Mengüç, Kyle Daun, Robert Siegel
In the next section, we outline the electromagnetic treatment of thermal radiation and briefly introduce the concepts of density of electromagnetic states (DOS) and coherence necessary to understand the physics of near-field radiative heat transfer. Then, evanescent waves and surface polaritons are overviewed. Subsequently, near-field radiative heat transfer between closely spaced bodies is explained in detail through flux calculations in a one-dimensional (1D) layered geometry. Finally, we discuss experimental works related to near-field thermal radiation.
Near-Field Radiative Heat Transfer between $\beta-$GeSe monolayers: An ab initio study
Published in Nanoscale and Microscale Thermophysical Engineering, 2023
R. Esquivel-Sirvent, A. Gusso, F. Sánchez Ochoa
The near field radiative heat transfer (NFRHT) between two bodies at different temperatures exceeds the value predicted by Stefan-Boltzmann law by several orders of magnitude [1]. This is true when the separation between the two bodies is less than Wien’s thermal wavelength . Since the original experiments of Hargreaves [2], this enhancement has been verified in many experiments [3–7]. From a theoretical point of view, the NFRHT is explained using fluctuation electrodynamics, which provides the mechanisms for the emission of thermally-excited electromagnetic fields [8, 9]. Within this theory, the far-field or Stefan-Boltzmann contribution comes from the propagating electromagnetic fields between the two bodies. In the near-field, there is an additional contribution due to the evanescent modes.
Near-field electromagnetic heat transfer through nonreciprocal hyperbolic graphene plasmons
Published in Nanoscale and Microscale Thermophysical Engineering, 2020
ChengLong Zhou, Shui-Hua Yang, Yong Zhang, Hong-Liang Yi
In summary, we theoretically prove that the application of a drift current to a graphene grating results in an extremely asymmetric modal dispersion and photonic transmission mode, which has never been noted in the noncontact heat exchanges at nanoscale before. These NHSPPs are excited by drift current in the graphene grating. In addition, analyses of the effects of drift current velocity, vacuum gap, graphene filling factor, chemical potential, and twisting angle on the NFRHT reveal some unique phenomena. By changing the strength of drift current, the frequency and intensities of the NHSPPs can be modulated, and hence the NFRHT can be tuned accordingly. As the graphene filling factor increases, the asymmetric modal in this wave vector gradually decreases. Interestingly, compared with the case of zero-current, the existence of the lower chemical potential and lower graphene filling factor results in a unique suppression of heat transfer with high drift current. Moreover, we have found that thanks to the nonreciprocal hyperbolic topology of the NHSPPs supported by the drift-biased graphene grating, at a large twisting angle, the system of a large drift current velocity is more preferable to modulate the NFRHT compared with the case of zero- current. The combined effect of drift current and graphene grating provides a tunable way to realize near-field electromagnetic energy modulation for devices. The fundamental understanding gained here will open a new way to spectrally tune near-field radiative heat transfer between metamaterials for energy conversion and thermal management. Moreover, the more interesting effects of drift current on other materials need to be further explored, such as elliptical materials and so on.