scholarly journals Thermal Emission Shaping and Radiative Cooling with Thermal Wells, Wires and Dots

2015 ◽  
Author(s):  
Svetlana V. Boriskina ◽  
Jonathan K. Tong ◽  
Lee A. Weinstein ◽  
Wei-Chun Hsu ◽  
Yi Huang ◽  
...  
Keyword(s):  
Thermal Emission ◽  
Radiative Cooling

Anisotropic Polarized Emission of a Doped Silicon Lamellar Grating

2006 ◽  
Vol 129 (1) ◽  
pp. 11-16 ◽  
Author(s):  
F. Marquier ◽  
M. Laroche ◽  
R. Carminati ◽  
J.-J. Greffet
Keyword(s):  
Surface Plasmons ◽  
Angular Dependence ◽  
Thermal Emission ◽  
Azimuthal Angle ◽  
Radiative Cooling ◽  
Polarized Emission ◽  
Doped Silicon ◽  
Resonant Emission ◽  
Thermal Sources ◽  
Total Hemispherical Emissivity

Thermal emission of a doped silicon grating has been studied in the plane perpendicular to the grooves. We show how the excitation of surface plasmons produce a resonant emission weakly depending on the polarization and azimuthal angle. We analyze in detail the polarization and angular dependence of the emission out of the plane perpendicular to the grooves. Two kinds of thermal sources, directional and quasi-isotropic, are studied. They have been designed in a previous paper. We also compute the total hemispherical emissivity of these gratings. In addition we show that in applications such as radiative cooling, these sources are less efficient than other structures.

scholarly journals Metamaterial-Based Radiative Cooling: Towards Energy-Free All-Day Cooling

Energies ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 89 ◽  
Author(s):  
Byoungsu Ko ◽  
Dasol Lee ◽  
Trevon Badloe ◽  
Junsuk Rho
Keyword(s):  
Near Infrared ◽  
Thermal Emission ◽  
Cooling System ◽  
Radiative Cooling ◽  
Future Perspectives ◽  
Direct Sunlight ◽  
Basic Principles ◽  
Atmospheric Window ◽  
Window Region ◽  
Reduce Energy Consumption

In the light of the ever increasing dangers of global warming, the efforts to reduce energy consumption by radiative cooling techniques have been designed, but are inefficient under strong sunlight during the daytime. With the advent of metamaterials and their selective control over optical properties, radiative cooling under direct sunlight is now possible. The key principles of metamaterial-based radiative cooling are: almost perfect reflection in the visible and near-infrared spectrum (0.3–3 µm) and high thermal emission in the infrared atmospheric window region (8–13 µm). Based on these two basic principles, studies have been conducted using various materials and structures to find the most efficient radiative cooling system. In this review, we analyze the materials and structures being used for radiative cooling, and suggest the future perspectives as a substitute in the current cooling industry.

scholarly journals Jupiter's post-impact atmospheric thermal response

1996 ◽  
Vol 156 ◽  
pp. 293-306
Author(s):  
Barney J. Conrath
Keyword(s):  
Time Scales ◽  
Thermal Emission ◽  
Thermal Structure ◽  
Radiative Cooling ◽  
Temperature Perturbation ◽  
Ambient Atmosphere ◽  
Height Range ◽  
Upper Troposphere ◽  
Entire Height ◽  
The Impact

Measurements of thermal emission in spectral regions, ranging from the near-infrared to mm wavelengths provide information on the atmospheric thermal structure over impact sites fromμbar levels in the upper stratosphere down to the upper troposphere. Systematic time series of observations relevant to this entire height range over individual spots do not exist. However, by piecing together information at different times from various spots, it is possible to obtain a provisional, semi-quantitative picture of the behavior of the thermal structure over a typical impact site. Immediately after fall-back of the ejecta plume, the upper stratosphere is heated to ∼ 600-1300 K above ambient temperature. The amplitude of the temperature perturbation diminishes with increasing depth in the atmosphere, but even in the upper troposphere a temperature increase of a few kelvins is observed. Initially, the upper stratosphere cools very rapidly with time scales of tens of minutes, presumably the result of strong radiative cooling associated with the high temperatures. After the initial cooling, all levels continue to cool at slower rates with time scales of a few days; however, this is still very rapid compared to radiative cooling of the ambient atmosphere. Enhancements in infrared opacity necessary to produce the cooling radiatively do not appear to be viable, suggesting that dynamical effects may play a dominant role. Possible mechanisms include horizontal mixing with the ambient atmosphere and adiabatic cooling produced by upward motion associated with an anticyclonic vortex. Many questions remain concerning the thermal structure above the impact sites; these are being addressed through ongoing data analysis and modeling efforts.

Measurement of lattice parameter at the nanometer scale using convergent-beam microdiffraction from a thermal emission source

1993 ◽  
Vol 51 ◽  
pp. 690-691
Author(s):  
W. T. Pike
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Thermal Emission ◽  
Lattice Parameter ◽  
Scanning Transmission Electron Microscope ◽  
Emission Source ◽  
Device Structure ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Convergent Beam

With the advent of crystal growth techniques which enable device structure control at the atomic level has arrived a need to determine the crystal structure at a commensurate scale. In particular, in epitaxial lattice mismatched multilayers, it is of prime importance to know the lattice parameter, and hence strain, in individual layers in order to explain the novel electronic behavior of such structures. In this work higher order Laue zone (holz) lines in the convergent beam microdiffraction patterns from a thermal emission transmission electron microscope (TEM) have been used to measure lattice parameters to an accuracy of a few parts in a thousand from nanometer areas of material.Although the use of CBM to measure strain using a dedicated field emission scanning transmission electron microscope has already been demonstrated, the recording of the diffraction pattern at the required resolution involves specialized instrumentation. In this work, a Topcon 002B TEM with a thermal emission source with condenser-objective (CO) electron optics is used.

Saturation mechanism and generated viscosity in gravito-turbulent accretion disks

2020 ◽  
Vol 640 ◽  
pp. A53
Author(s):  
L. Löhnert ◽  
S. Krätschmer ◽  
A. G. Peeters
Keyword(s):  
Growth Rate ◽  
Numerical Simulations ◽  
Accretion Disks ◽  
Gravitational Instability ◽  
Turbulent Viscosity ◽  
Radial Distance ◽  
Maximum Growth ◽  
Wave Number ◽  
Radiative Cooling ◽  
Mixing Length

Here, we address the turbulent dynamics of the gravitational instability in accretion disks, retaining both radiative cooling and irradiation. Due to radiative cooling, the disk is unstable for all values of the Toomre parameter, and an accurate estimate of the maximum growth rate is derived analytically. A detailed study of the turbulent spectra shows a rapid decay with an azimuthal wave number stronger than ky−3, whereas the spectrum is more broad in the radial direction and shows a scaling in the range kx−3 to kx−2. The radial component of the radial velocity profile consists of a superposition of shocks of different heights, and is similar to that found in Burgers’ turbulence. Assuming saturation occurs through nonlinear wave steepening leading to shock formation, we developed a mixing-length model in which the typical length scale is related to the average radial distance between shocks. Furthermore, since the numerical simulations show that linear drive is necessary in order to sustain turbulence, we used the growth rate of the most unstable mode to estimate the typical timescale. The mixing-length model that was obtained agrees well with numerical simulations. The model gives an analytic expression for the turbulent viscosity as a function of the Toomre parameter and cooling time. It predicts that relevant values of α = 10−3 can be obtained in disks that have a Toomre parameter as high as Q ≈ 10.

Application of Backside Photo and Thermal Emission Microscopy Techniques to Advanced Memory Devices

1997 ◽  
Author(s):  
S.-S. Lee ◽  
J.-S. Seo ◽  
N.-S. Cho ◽  
S. Daniel
Keyword(s):  
Thermal Emission ◽  
Test Cases ◽  
Memory Devices ◽  
Front Side ◽  
Emission Analysis ◽  
Intensity Attenuation ◽  
Analysis Techniques ◽  
Defect Sites ◽  
Emission Microscopy ◽  
Microscopy Techniques

Abstract Both photo- and thermal emission analysis techniques are used from the backside of the die colocate defect sites. The technique is important in that process and package technologies have made front-side analysis difficult or impossible. Several test cases are documented. Intensity attenuation through the bulk of the silicon does not compromise the usefulness of the technique in most cases.

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