Thermal return reflection method for resolving emissivity and temperature in radiometric measurements

Woskov, P.; Sundaram, S. K.

doi:10.1063/1.1516864

Cited by 23 publications

(23 citation statements)

References 8 publications

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“…The equations for interpreting this data need to include the emission and absorption by the waveguide. From Reference [11] they are: 32% lower than that for the molten glass. The difference in coupling factor suggests that the molten salt surface is a smoother, flatter surface (due to its low viscosity hence smooth covering) than the glass melt at these wavelengths.…”

Section: Resultsmentioning

confidence: 82%

“…Temperature and emissivity information were obtained from the broadband MMW thermal signal, which is proportional to the product of emissivity and temperature Thermal return reflection (TRR) [11] measurements were taken to obtain a quantitative measure of the surface emissivity. In the TRR method a beamsplitter at the receiver redirects a portion of the thermal signal back to the melt as a probe of its reflectivity.…”

Section: Methodsmentioning

confidence: 99%

“…The resulting increase in thermal signal depends on the emissivity (ε) and surface figure for coupling (τ k ) the radiation back to the receiver, were the surface figure depends on the surface roughness, curvature, and alignment. In the present experiment the instrumentation layout is the same as in [11] except that the positions of the receiver and return mirror are interchanged relative to the beamsplitter so that the beamsplitter reflectivity, r bs and transmission, τ bs are also interchanged in the equations of [11] for analysis of the data here.…”

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Molten salt dynamics in glass melts using millimeter-wave emissivity measurements

Woskov

Sundaram

Daniel

et al. 2004

Journal of Non-Crystalline Solids

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Section: Resultsmentioning

confidence: 82%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Molten salt dynamics in glass melts using millimeter-wave emissivity measurements

Woskov

Sundaram

Daniel

et al. 2004

Journal of Non-Crystalline Solids

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“…Thermal analysis by MMW radiometry methods [1] can be combined with MMW high power gyrotron radiation [2] to enable unique capability to research the thermodynamic properties of materials to extreme temperatures that have not been accessible to real time dynamic studies in the past. In particular, the properties of rocks melts up to the vaporization temperature can be quantitatively studied.…”

Section: Introductionmentioning

confidence: 99%

Millimeter-Wave Heating, Radiometry, and Calorimetry of Granite Rock to Vaporization

Woskov

Michael

2011

J Infrared Milli Terahz Waves

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Abstract:Millimeter-wave (MMW) technologies can provide unique heating and diagnostic capabilities to research the thermal dynamics of materials to extreme temperatures. The MMW properties of rocks in the molten state up to their vaporization temperatures are not well known. Using a 28 GHz gyrotron beam collinear with a 130 GHz radiometry view in a calorimetric chamber, the transitions of granite rock specimens through solid phases, melting, and vaporization were observed, including release of trapped trace gas (< 0.07%). The 28 GHz emissivity of molten granite was observed to be approximately constant at 0.66 ± 0.03 up to vaporization where it increased to 0.70 ± 0.03 at an equilibrated temperature of 2710 ± 120 °C. An analysis of the thermal power balance during a 76 s steady state vaporization time period indicates that the MMW emissivity of the molten granite is larger than in the infrared. The observations support the possibility that MMW thermal ablative penetration into hot crystalline rock formations could be a more practical approach than infrared laser drilling to access deep resources.

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“…The receiver receives signals from the sample and transmits a MMW probe signal back to the sample to monitor reflections. The temperature and emissivity of the monitored surface were obtained by measuring the MMW thermal radiation from the surface and using this radiation by the thermal return reflection mirror as a probe of the surface reflectivity (Woskov and Sundaram 2002). The sample temperature and emissivity were calculated using the equations 3.1 through 3.4.…”

Section: Emissivity Measurementsmentioning

confidence: 99%

Thermal Wadis in Support of Lunar Exploration: Concept Development and Utilization

Matyáš¹,

Wegeng²,

Burgess³

2009

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SummaryThermal wadis, engineered sources of heat, can be used to extend the life of lunar rovers by keeping them warm during the extreme cold of the lunar night. Thermal wadis can be manufactured by sintering or melting lunar regolith into a solid mass with more than two orders of magnitude higher thermal diffusivities compared to native regolith dust. Small simulant samples were sintered and melted in the electrical furnaces at different temperatures, different heating and cooling rates, various soaking times, under air, or in an argon atmosphere. The samples were analyzed with scanning electron microscopy and energy dispersive spectroscopy, X-ray diffraction, a laser-flash thermal diffusivity system, and the millimeter-wave system. The melting temperature of JSC-1AF simulant was ~50°C lower in an argon atmosphere compared to an air atmosphere. The flow of argon during sintering and melting resulted in a small mass loss of 0.04 to 0.1 wt% because of the volatization of alkali compounds. In contrast, the samples that were heat-treated under an air atmosphere gained from 0.012 to 0.31 wt% of the total weight. A significantly higher number of cavities were formed inside the samples melted under an argon atmosphere, possibly because of the evolution of oxygen bubbles from iron redox reactions. The calculated emissivity of JSCf-1AF simulant did not change much with temperature, varying between 0.8 and 0.95 at temperatures from 100 to 1200°C. The thermal diffusivities of raw regolith that was compressed under a pressure of 9 metric tons ranged from 0.0013 to 00011 in the 27 to 390°C temperature range. The thermal diffusivities of sintered and melted JSC-1AF simulant varied from 0.0028 to 0.0072 cm 2 /s with the maximum thermal diffusivities observed in the samples that were heated up 5°C/min from room temperature to 1150°C under argon or air. These thermal diffusivities are high enough for the rovers to survive the extreme cold of the Moon at the rim of the Shackleton Crater and allow them to operate for months (or years) as opposed to weeks on the lunar surface. Future investigations will be focused on a system that can efficiently construct a thermal wadi from the lunar mare regolith. Solar heating, microwave heating, or electrical resistance melting are considered.

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Thermal return reflection method for resolving emissivity and temperature in radiometric measurements

Cited by 23 publications

References 8 publications

Molten salt dynamics in glass melts using millimeter-wave emissivity measurements

Molten salt dynamics in glass melts using millimeter-wave emissivity measurements

Millimeter-Wave Heating, Radiometry, and Calorimetry of Granite Rock to Vaporization

Thermal Wadis in Support of Lunar Exploration: Concept Development and Utilization

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