Near-Field Thermal Radiation: Comparison of Numerical Results and Experiments

2008 ◽  
Author(s):  
Arvind Narayanaswamy ◽  
Sheng Shen ◽  
Gang Chen
Keyword(s):  
Radiative Transfer ◽  
Thermal Radiation ◽  
Numerical Technique ◽  
Near Field ◽  
Blackbody Radiation ◽  
Numerical Results ◽  
Silica Substrate ◽  
Order Of Magnitude ◽  
Proximity Force Approximation ◽  
Curved Objects

Near–field radiative transfer between two objects can be enhanced by a few order of magnitude compared to the far–field radiative transfer that can be described by Planck’s theory of blackbody radiation and Kirchoffs laws. We have developed a numerical technique to determine the near–field thermal radiative transfer between two spheres. We have measured near–field thermal radiation between a silica sphere and a flat silica substrate as a function of gap between them using an bi–material cantilever as a thermal sensor. The experimental results show qualitative agreement with numerical results. The results of this work indicate that the proximity force approximation, widely used to determine forces between curved objects, is not applicable to near–field radiative transfer between curved objects.

Heat Transfer Spectroscopy and “Heat Transfer-Distance” Curves

2008 ◽  
Author(s):  
Arvind Narayanaswamy ◽  
Sheng Shen ◽  
Gang Chen
Keyword(s):  
Heat Transfer ◽  
Radiative Transfer ◽  
Atomic Force Microscope ◽  
Near Field ◽  
Surface Force ◽  
Casimir Forces ◽  
Distance Curve ◽  
Transfer Distance ◽  
Atomic Force ◽  
Order Of Magnitude

Thermal radiative transfer between objects as well as near-field forces such as van der Waals or Casimir forces have their origins in the fluctuations of the electrodynamic field. Near-field radiative transfer between two objects can be enhanced by a few order of magnitude compared to the far-field radiative transfer that can be described by Planck’s theory of blackbody radiation and Kirchoff’s laws. Despite this common origin, experimental techniques of measuring near-field forces (using the surface force apparatus and the atomic force microscope) are more sophisticated than techniques of measuring near-field radiative transfer. In this work, we present an ultra-sensitive experimental technique of measuring near-field using a bi-material atomic force microscope cantilever as the thermal sensor. Just as measurements of near-field forces results in a “force distance curve”, measurement of near-field radiative transfer results in a “heat transfer-distance” curve. Results from the measurement of near-field radiative transfer will be presented.

Near-Field Radiative Heat Transfer Between Spherical Surfaces

2009 ◽  
Author(s):  
Arvind Narayanaswamy ◽  
Sheng Shen ◽  
Gang Chen
Keyword(s):  
Heat Transfer ◽  
Radiative Transfer ◽  
Near Field ◽  
Blackbody Radiation ◽  
Experimental Investigations ◽  
Flat Substrate ◽  
Spherical Surfaces ◽  
Radiation Theory ◽  
Theoretical Predictions ◽  
Afm Cantilever

Nearfield radiative transfer is known to be significantly different from that of far-field radiative transfer based on Plancks theory of blackbody radiation. Theoretical predictions point to a significant enhancement of radiative transfer between closely spaced objects due to the tunneling of surface phonon polaritons. Despite extensive theoretical predictions of enhancement between parallel surfaces, experimental evidence of near-field radiative transfer in excess of Plancks limit has been elusive due to experimental difficulties. In this talk, we will present results of our theoretical and experimental investigations into near-field radiative transfer between spherical surfaces. We have developed a sensitive technique of measuring nearfield radiative transfer between a microsphere and a substrate using a bimaterial atomic force microscope (AFM) cantilever, resulting in heat transfer-distance curves. Measurements of radiative transfer between a sphere and a flat substrate show the presence of strong nearfield effects resulting in enhancement of heat transfer over the predictions of the Planck blackbody radiation theory.

Nanoscale Thermal Radiation Between Coated Spheres

2017 ◽  
Author(s):  
Braden Czapla ◽  
Arvind Narayanaswamy
Keyword(s):  
Radiative Transfer ◽  
Thermal Radiation ◽  
Near Field ◽  
Reflection Coefficients ◽  
Far Field ◽  
Surface Phonon ◽  
Surface Phonon Polariton ◽  
Silver Spheres ◽  
New Formula ◽  
Coated Spheres

In this work, we present a new formula for the near-field thermal radiative transfer between two spheres. The formula is identical for coated or uncoated spheres and captures the effect of the coatings in the effective Mie reflection coefficients of the spheres. We also numerically demonstrate that silica coated silver spheres transition from silver-like conductance in the far-field to surface phonon polariton dominated silica-like behavior in the extreme near-field.

A Generalized Landauer Formalism of Nanoscale Thermal Radiative Transfer

2012 ◽  
Author(s):  
Arvind Narayanaswamy
Keyword(s):  
Radiative Transfer ◽  
General Theory ◽  
General Framework ◽  
Near Field ◽  
Length Scale ◽  
Thermal Radiative Transfer ◽  
Curved Objects ◽  
Fluctuational Electrodynamics

Though the dependence of near-field radiative transfer on the gap between two planar objects is well understood and that between curved objects is becoming clearer, a general theory of micro and nanoscale radiative transfer is still unavailable. Here, I describe a general framework based on Rytov’s theory of fluctuational electrodynamics that can be used to analyze radiative transfer between any two structures, independent of their length scale.

scholarly journals Near-field thermal radiation between two closely spaced glass plates exceeding Planck’s blackbody radiation law

2008 ◽  
Vol 92 (13) ◽  
pp. 133106 ◽  
Author(s):  
Lu Hu ◽  
Arvind Narayanaswamy ◽  
Xiaoyuan Chen ◽  
Gang Chen
Keyword(s):  
Thermal Radiation ◽  
Near Field ◽  
Blackbody Radiation ◽  
Glass Plates

Near-field scanning optical microscopy

1986 ◽  
Vol 44 ◽  
pp. 642-643
Author(s):  
E. Betzig ◽  
A. Harootunian ◽  
M. Isaacson ◽  
A. Lewis
Keyword(s):  
Near Field ◽  
Optical Microscope ◽  
Visible Radiation ◽  
Field Methods ◽  
Optical Elements ◽  
Optical Region ◽  
Order Of Magnitude ◽  
Nondestructive Imaging ◽  
Scanning Optical Microscopy ◽  
Near Field Scanning

In general, conventional methods of optical imaging are limited in spatial resolution by either the wavelength of the radiation used or by the aberrations of the optical elements. This is true whether one uses a scanning probe or a fixed beam method. The reason for the wavelength limit of resolution is due to the far field methods of producing or detecting the radiation. If one resorts to restricting our probes to the near field optical region, then the possibility exists of obtaining spatial resolutions more than an order of magnitude smaller than the optical wavelength of the radiation used. In this paper, we will describe the principles underlying such "near field" imaging and present some preliminary results from a near field scanning optical microscope (NS0M) that uses visible radiation and is capable of resolutions comparable to an SEM. The advantage of such a technique is the possibility of completely nondestructive imaging in air at spatial resolutions of about 50nm.

Near-field and far-field effects in thermal radiation from metallic carbon nanotubes

2007 ◽  
Author(s):  
Andrei M. Nemilentsau ◽  
Gregory Ya. Slepyan ◽  
Sergey A. Maksimenko
Keyword(s):  
Carbon Nanotubes ◽  
Thermal Radiation ◽  
Near Field ◽  
Far Field ◽  
Field Effects

Sorption of radionuclides to a cementitious backfill material under near-field conditions

2012 ◽  
Vol 76 (8) ◽  
pp. 3401-3410 ◽  
Author(s):  
M. Felipe-Sotelo ◽  
J. Hinchliff ◽  
N. Evans ◽  
P. Warwick ◽  
D. Read
Keyword(s):  
Organic Compounds ◽  
Degradation Products ◽  
Cellulose Degradation ◽  
Near Field ◽  
Organic Ligand ◽  
Sorption Isotherms ◽  
Field Conditions ◽  
Sorption Behaviour ◽  
Backfill Material ◽  
Order Of Magnitude

AbstractThe sorption behaviour of I−, Cs+, Ni2+, Eu3+, Th4+ and UO2+2on NRVB (Nirex reference vault backfill) a possible vault backfill, at pH 12.8 was studied. Sorption isotherms generated were compared to results obtained in the presence of cellulose degradation products (CDP). Whereas Cs was not affected by the presence of the organic compounds, a notable reduction in the sorption of Th and Eu to cement was observed. The results also indicated limited removal of Ni from solution (with or without an organic ligand) by sorption, the concentration in solution seemingly being determined solely by solubility processes. In the case of uranium, the presence of CDP increased the sorption to cement by almost one order of magnitude. Further studies into the uptake of CDP by cement are being undertaken to identify the mechanism(s) responsible.

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