Blackbody Radiation Theory Research Articles

Claude Ziad El-A Proposed Algorithm for Detecting Invisible Celestial Objects by Generalizing the Planck’s Blackbody Radiation Law

Blackbody radiation was proposed by Planck to measure the temperature of a body by observing its electromagnetic waves spectrum. However, when it comes to massive objects such as stars, other factors can affect the emitted wavelength of the light from the body, such as gravitational field and doppler effect, which are caused not only by the star but also by the observer (i.e., Earth). Hence, predicting the surface temperature of a star by using only its radiation might not be accurate especially for massive stars. To solve the problem, and to give more accuracy to the measurement, this paper proposes an algorithm and a modification of the Plank’s blackbody radiation theory by considering the impact of relativistic Doppler effect and the gravitational field of both, the emitter (i.e., star), and the receiver (i.e., Earth). For validation purposes, the proposed modification theory is compared to the original one proposed by Planck using four different case studies, (a) sun is considered as an emitter and the earth as the receiver; (b) a massive star is considered as an emitter and the earth as a receiver; (c) the earth is considered as an emitter and a massive star as a receiver; finally (d) two identical stars are considered as emitter and receiver, respectively. Results show that our proposed method works perfectly and gives more accurate results compared to the traditional Plank’s theory since the impact of gravitational field and Doppler effect on the spectrum are considered.

On the nuclear explosion fireball

For a nuclear explosion (fireball), the radiation energy to particle gas energy ratio at different stages is studied. Besides, some basic results of blackbody radiation theory are applied to study some important and useful quantities of the Trinity Test fireball.

A new high-precision star map simulation model and experimental verification

In order to meet the ground test requirements of star sensors and solve the problem of the non-linearity between the apparent magnitude and the total grey value of the stars encountered in actual measurement, the colour index of stars and the theory of blackbody radiation are introduced to modify the simulation model which only used apparent magnitude formerly. In addition, simulation accuracy evaluation parameters are established based on the characteristics of star points. Finally, practical star observation experiments are carried out with a KAI-4021 detector as an example. Through the comparison between the measured and simulated star maps, the average grey-scale error is less than 12%, which is typically smaller than that of AGS model, and the error is reduced by 5% to 15%. The experimental results show that the proposed star map simulation method has higher accuracy and can provide star maps for star sensor ground tests. https://doi.org/10.1364/99.099999

Infrared emission properties of a kind of natural carbonate: interpretation from mineralogical analysis

In recent years, infrared radiation materials have received extensive attention. In this study, a kind of natural carbonate rock was highlighted and its radiation mechanism investigated, using a series of mineralogical and spectroscopy studies such as optical microscope, varying-temperature X-ray diffraction (XRD), Raman spectroscopy, X-ray fluorescence spectrometer (XRF), inductively coupled plasma mass spectrometry (ICP-MS), electron microprobe analysis (EMPA), thermogravimetry, differential thermal analysis (TG/DTA), environment scanning electron microscopy (ESEM) and infrared absorption and emission spectroscopy (IR). Results indicated that micro-nanoscale calcite (95%), graphite (3%) and pyrite (0.1%) were the primary components. Additionally, Sr2+ and Mg2+ were found to substitute Ca2+ in calcite, whose content could reach 0.145% and 0.152% (wt%), respectively. On the basis of blackbody radiation theory and the radiation energy spectrum of samples from 400 to 2000 cm−1, the average emissivity of this rock, pure calcite, pyrite and graphite was calculated as 1.007, 0.986, 0.899 and 0.488, respectively, in the temperature range of 50–140 °C. Notably, the radiation energy spectrum calculated emissivity and emission spectrum of calcite showed high consistency with the natural carbonate at all temperatures, indicating that the radiation performance of the rock was principally contributed to calcite. The heat capacity of three components presented a positive correlation with their infrared emissivity values within the temperature and wavelength of this study. The highest heat capacity of calcite benefited the enhancement of the whole thermal radiation performance of carbonate rock. The vibration of C–O bonds in the narrow absorption band of emission spectrum (1350–1500 cm−1) would lead to relatively high radiation energy and emissivity. In addition, the substitution of Mg2+ and Sr2+ for Ca2+ improved the infrared radiation characteristics due to the 6–8% enhancement of average emissivity for pure MgCO3 and SrCO3 compared to CaCO3. This study can provide theoretical reference for infrared radiation material, using abundant and cheap natural minerals on the Earth as a source of raw materials for infrared functional materials.

Particle transport mode during flash sintering of sodium bismuth titanate ceramic

In this work, the NBT ceramics are successfully flash sintered at a direct current 30 mA/mm 2 for 30 s under different initial electric field. Subsequently, the actual temperature of samples is estimated by blackbody radiation theory under different conditions. The calculation results show that the sample temperature is close to the densification temperature of NBT ceramics used in conventional method. The rapid densification mechanism is discussed by wetting of local contact particles due to the asymmetrical Joule heating. In particular, we analyzed the particle transport mode during flash sintering in terms of particle diffusion. It is believed that the transform in the particles transport mode from solid diffusion to flow mass transfer accelerated the particles diffusion rate, which ensure the particle rearrangement and achieve the local shrinkage of particles in a short period of time.

Host‐Sensitized Continuum‐Broad‐Band White‐Light Emitting Yb2O3:Er3+ Phosphor under CW‐NIR Light Absorption

AbstractSingle cubic phase Yb2O3:Er3+ phosphors have been synthesized via solid state reaction technique and characterized by X‐ray diffraction (XRD) and Field emission scanning electron microscopy (FE‐SEM) analysis. An unusual continuum broad band white colour upconversion (UC) emission has been observed under 980 nm continuous wave (CW) near infrared (NIR) laser diode excitation. Interestingly, the phosphor shows characteristic erbium ion transitions at low pump power, but at high pump power heat associated continuum broad band emission was realized. The continuum broad band emission was explained on the basis of energy level diagram, laser induced pump power dependence and blackbody radiation theory. The heat associated/incandescence‐like light is originated due to heating induced by the nonradiative relaxation followed by sensitization (Yb → Er) and Yb−Yb dimer formation. The synthesized phosphor emits effective broad band white colour emission under high pump power and colour co‐ordinates (white colour: 0.34, 0.32) were located in the chromaticity diagram. Intrinsic optical bistability (IOB) behavior shows the hysteresis‐like loop originated upon variation in the laser pump power. The observed high temperature at point of irradiation of the prepared nanocrystalline phosphor is about ∼ 2442 K at 1430 mW, which is high as compare to tungsten bulb (2400 K for 100 W). The developed phosphors can be useful in white light production, solar cell efficiency enhancement, switchable bistable and as light to heat converter.

The Bose-Einstein condensate temperature of an ideal blackbody

The oscillators of a perfect blackbody are considered as non-interacting entities. Thus, Bose-Einstein Condensation is possible for these entities. The Bose-Einstein Condensate (BEC) temperature of a perfect blackbody is calculated from the Planck’s theory of blackbody radiation and de Broggle’s wave-particle duality relation. It is observed that the BEC temperature of an ideal blackbody is 4.0K. Thus, bellow 4.0K temperature the energy density vs wavelength plot of a blackbody would look like a delta function. In this region, a blackbody would absorb or emit radiation of unique frequency depending upon its temperature. It is also possible to calculate the rest mass and the ground state vibrational energy of the oscillators of a blackbody using present formalism.

Research and Verification of Blackbody Radiation Law

<p>Blackbody radiation theory is one of the important origins of light quantum theory in the twentieth century. It is not only an important basis for quantum mechanics and photonics theory, but also an important conclusion of blackbody radiation, and an important foundation of modern measurement. In the early nineteenth century, the study of thermal radiation was supported by thermodynamics and spectroscopy, and the rapid development of electromagnetism and optics was used. By the end of the 19th century, it was recognized that both the thermal radiation and the optical radiation were electromagnetic waves, and began to study the distribution of radiant energy in different frequency ranges, especially the study of blackbody radiation in theory and practice. Blackbody radiation experiment is one of the contents of modern physics experiment in colleges and universities. This paper mainly studies and validates the law of blackbody radiation by the WGH-10 blackbody experimental device. There is already a calibrated bromine tungsten lamp energy curve at 2940k. At the beginning of the experiment, we should scan at 2940k color temperature to get the baseline, and then calculate the transfer function. Again, the energy curve obtained by scanning at different color temperatures is divided by the transfer function to obtain the correct energy radiation curve. The experimental study of blackbody radiation by computer scanning grating spectrometer and bromine tungsten lamp was carried out. By means of scrolling grating and sine mechanism, the data were recorded by computer scanning to verify the three laws of blackbody radiation directly, and the radiation, transmission and reception of blackbody were analyzed Error correction. </p>

Infrared radiation characterization of several stainless steel textiles in the 3.5–5.1 μm infrared range

The infrared emission of four stainless steel textiles was characterized in the mid-infrared range, i.e. 3.6÷5.1 μm, by observing their temperature evolution under heating regime. The investigated steel textiles differ by the type of fabrics, resulting in some variation in the infrared emission. Standard test method for measuring emissivity was applied to the set of metallic textiles using infrared imaging radiometers as well as a reference surface of known high emissivity. The obtained experimental results allowed to retrieve the infrared emissivity at different applied temperatures. The experimental data were interpreted by means of Plank's theory of black-body radiation. Finally, all the investigated textiles appear to be suitable for thermal shielding applications.

High-temperature sensor instrumentation with a thin-film-based sapphire fiber.

A novel sapphire fiber-optic high-temperature sensor has been designed and fabricated based on blackbody radiation theory. Metallic molybdenum has been used as the film material to develop the blackbody cavity, owing to its relatively high melting point compared to that of sapphire. More importantly, the fabrication process for the blackbody cavity is simple, efficient, and economical. Thermal radiation emitted from such a blackbody cavity is transmitted via optical fiber to a remote place for detection. The operating principle, the sensor structure, and the fabrication process are described here in detail. The developed high-temperature sensor was calibrated through a calibration blackbody furnace at temperatures from 900°C to 1200°C and tested by a sapphire crystal growth furnace up to 1880°C. The experimental results of our system agree well with those from a commercial Rayteck MR1SCCF infrared pyrometer, and the maximum residual is approximately 5°C, paving the way for high-accuracy temperature measurement especially for extremely harsh environments.

Light-induced confinement of electrons in stacked distorted graphene layers - a (TD-)DFT study.

Recently observed white-light emission from graphene ceramics cannot be explained by black body radiation theory because of a relatively low temperature of the sample. Furthermore the intensity of the emission stays at the same level even at temperatures as low as 10 K, indicating the purely electronic nature of the observed emission. In this work a model of light emission from locally interacting stacked graphene layers after intense continuous wave laser excitation is proposed. After a light-induced sp2 to sp3 change of the hybridization sp2-nanodomains surrounded by sp3 carbon atoms could be created and the electrons can be confined. Using DFT and TD-DFT methods followed by a molecular-like approach we examine the electronic structure and the optical properties of graphene (sp2,sp3)-clusters. We show the quantized and well separated energy levels of electrons from the domain's interior and the possibility of emission in the NIR/VIS/UV range.

Temperature dependent emissivity of different stainless steel textiles in the infrared range

We experimentally investigated the infrared properties of a set of steel textiles, prepared using different type of fabrics. Infrared emission of the textiles was characterized in the mid-infrared range, i.e. 8÷14 μm, by observing their temperature evolution under heating regime with a focal plane array (FPA) infrared camera. Standard test method for measuring and compensating emissivity using infrared imaging radiometers was applied to the set of metallic textiles. The obtained experimental results allowed to retrieve the infrared emissivity at different applied temperatures. Although their infrared emission show some differences depending on the specific fabric, all the investigated textiles composed of steel yarns appear to be suitable for thermal shielding applications. Finally, the measured data were interpreted by means of the finite-difference time-domain (FDTD) numerical simulations as well as using Plank's theory of black-body radiation.

Synthesis and electrical field-assisted sintering behaviour of yttria-stabilized tetragonal ZrO2 nanopowders by polyacrylamide gel method

The tetragonal ZrO2 nanopowders stabilized with 3 mol% Y2O3 (3YSZ) were synthesized using a polyacrylamide gel method. The mean particle size of the 3YSZ nanopowders was found to decrease with increasing molecular ratio of monomer to the precursor salt. The 3YSZ nanopowders with mean particle size of 12 nm can be densified in 1 h at 800∘C, by the application of a d.c. electrical field. Under a constant d.c. electrical field, the current density through the specimen of 3YSZ rose rapidly when the temperature increased to a certain value. In the sintering process, the current density was restricted when the sharp increase occurred. By limiting current density to different values for one hour, it was found that current density was the most important factor in electrical field-assisted sintering process. The grain size of 3YSZ bulk increased with the enhanced current density. The stable stage of electrical field-assisted sintering process can be explained by Joule heating. Corresponding real temperature of specimens is estimated by applying black body radiation theory.

Up-conversion luminescence from single vanadate through blackbody radiation harvesting broadband near-infrared photons for photovoltaic cells

Up-conversion (UC) is a promising route to harvest near-infrared (NIR) sunlight and enhance the power conversion efficiency (PCE) of photovoltaic (PV) cells. However, most of the UC materials have some bottleneck problems associated with them, such as own only narrower excitation band matching with the sun spectrum, lower UC luminescence efficiency, and considerable heat losses. Thus, it is essential to design and find a UC material that can absorb broadband NIR photons through an attractive route named thermal radiation for photon energy UC. In this work, we investigated the UC luminescence properties of single CeVO4 materials, in which the excitation bands can be augmented at least a range of 808–1064 nm. We also confirmed that this kind of UC emission is triggered by the thermal absorption of VO43−, which might be expanded to other single vanadate materials. The UC luminescence mechanisms were analyzed by power dependence and temperature modeling, and interpreted in terms of blackbody radiation theory. We demonstrated the possibility of photocurrent response in thin-film-hydrogenated amorphous silicon solar cell modified with CeVO4 powders through blackbody radiation for harvesting NIR photons. Such single vanadate materials can absorb broader NIR photons for UC luminescence through blackbody radiation, will open a new door for the enhancement of the PCE in the next-generation concentrated PV cells.

Understanding the Flash Sintering of Rare‐Earth‐Doped Ceria for Solid Oxide Fuel Cell

A novel electrical current applied technique known as flash sintering has been applied to rapidly (within 10 min) densify electrolytes including Ce0.8Gd0.2O1.9 (GDC20), Ce0.9Gd0.1O1.95 (GDC10), and Ce0.8Sm0.2O1.9 (SDC20) for application in Solid Oxide Fuel Cells (SOFCs). The densification temperature for the three electrolytes was 554°C, 635°C, and 667°C, respectively, which is far below conventional sintering temperatures. All specimens after flash sintering maintained the pure fluorite structure and exhibited a well‐densified microstructure. To investigate the flash‐sintering mechanism, we have applied Joule heating effect with blackbody radiation theory, and found that this theory could reasonably interpret the flash‐sintering phenomenon by matching theoretically calculated temperature with the real temperature. More importantly, one of the materials inherent properties, the electronic conductivity, has been found correlated with the onset of flash sintering, which indicates that the electrons and holes are the primary current carriers during the start of flash‐sintering process. As a result, potential densification mechanisms have been discussed in terms of spark plasma discharge.

Notes on Contributors

Notes on Contributors

Wavelength-band Transformation Method of Gray-body Infrared Image Using Surface Temperature Estimation

Infrared (IR) imaging systems obtain thermal images by converting surface temperature into two-dimensional images by measuring IR radiation from an object’s surface. This research proposes a wavelength-band transformation method to convert an IR image of an arbitrary wavelength-bandwidth into an IR image of another wavelength-bandwidth. We estimate the temperature of an arbitrary wavelength by obtaining the radiance from the black body radiation theory and the linear transformation function of the gray level from the radiance. We generate an IR image for another wavelength-bandwidth by calculating the radiance of another wavelength-bandwidth using the estimated temperature. The validity of the proposed method was verified through simulations. The IR target image was generated using RadThermIR software, and images, acquired from a thermal observation device, were used as IR background image.

An improved direct current sintering technique for proton conductor – BaZr0.1Ce0.7Y0.1Yb0.1O3: The effect of direct current on sintering process

BaZr0.1Ce0.7Y0.1Yb0.1O3 (BZCYYb), a promising proton conductor of poor sinterability used in Solid Oxide Fuel Cells (SOFCs), has been densified in one hour at 850 °C by applying direct current sintering technique (DC-sintering). Under a constant electrical field, the current density through the specimen of BZCYYb rises rapidly when the temperature increases to a certain value. In DC-sintering process, we restrict the current density when the sharp increase occurs. By limiting current density to different values for one hour, we find that current density is the most important factor in DC-sintering process. The conductivity and the grain size of BZCYYb electrolyte increase significantly with the enhanced current density, while the different initial applied electrical fields have negligible effect. The stable stage of DC-sintering process can be explained by Joule heating. Corresponding real temperature of specimens is estimated by applying black body radiation theory.

Modeling and validation of photometric characteristics of space targets oriented to space-based observation

A modeling and validation method of photometric characteristics of the space target was presented in order to track and identify different satellites effectively. The background radiation characteristics models of the target were built based on blackbody radiation theory. The geometry characteristics of the target were illustrated by the surface equations based on its body coordinate system. The material characteristics of the target surface were described by a bidirectional reflectance distribution function model, which considers the character of surface Gauss statistics and microscale self-shadow and is obtained by measurement and modeling in advance. The contributing surfaces of the target to observation system were determined by coordinate transformation according to the relative position of the space-based target, the background radiation sources, and the observation platform. Then a mathematical model on photometric characteristics of the space target was built by summing reflection components of all the surfaces. Photometric characteristics simulation of the space-based target was achieved according to its given geometrical dimensions, physical parameters, and orbital parameters. Experimental validation was made based on the scale model of the satellite. The calculated results fit well with the measured results, which indicates the modeling method of photometric characteristics of the space target is correct.

Infrared characteristics of on-orbit targets based on space-based optical observation

A modeling method of infrared characteristics of the on-orbit target was presented by a comprehensive consideration of the influence of structure, material, background, attitude and surface self-shadowing of the target at the larger scale. A physical and mathematical model of background radiation was established based on the blackbody radiation theory. The target surface was divided into regions based on structure and material properties and each region was divided into grids by finite element method. Bidirectional Reflection Distribution Function (BRDF) measured in advance was introduced to describe infrared reflection characteristics of each grid and a mathematical model on reflected radiation of the target was built by summing reflection of each grid. The thermal equilibrium temperature of the target surface was calculated by node network method and a mathematical model on emitted radiation of the target was built. Then a body coordinate system was set to describe the relative positions of the target, background radiation sources and detector by coordinate conversion and determine contributed surfaces of the target to the detector. Simulation of the target infrared characteristics on orbit was achieved. The results provide a feasibility of using material properties for satellite detection to within the accuracy of materials measurement and real-time simulation capabilities of computer.