Blackbody Radiation Research Articles

Decoherence of a matter wave by blackbody radiation

Decoherence of a matter wave by blackbody radiation

Experimental investigations of 9 mol.% Mo5SiB2 isopleth phase diagram in Mo–Mo5SiB2–TiC pseudo-ternary system

The present work focuses on gaining a systematic understanding of the microstructure variation and solidification reactions of alloys in the Mo-rich portion of the Mo–Mo5SiB2(T2)–TiC pseudo-ternary system. A series of MoSiBTiC alloys with 9mol% T2 were selected from the vicinity of the Mo–TiC binary and Mo–Mo5SiB2(T2)–TiC ternary eutectic point to carefully examine the solidification pathway and phase diagram. The solidification reaction temperature of the alloys was detected via an ultra-high-temperature thermal analysis method using blackbody radiation. Solidification was observed in situ using an electromagnetic levitation (EML) apparatus, and the microstructure evolution of solidified EML samples under different thermal histories was characterized. The results provide an experimentally based reassessment of the liquidus surface projection. The primary Moss phase region is shown to be larger than indicated in previously reported data, and a Mo2B primary region should exist in the triangle. As the main result of the investigation of the solidification pathway of a series of MoSiBTiC alloys, an isopleth phase diagram with 9mol.% T2 in Mo–Mo5SiB2(T2)–TiC pseudo-ternary system is presented.

Improvement strategy evaluation from coupled energy-flow perspective on the GaSb thermophotovoltaic cell

Thermophotovoltaic (TPV) emerges as a novel high-efficiency generation technology, showcasing enormous potential in various sustainable energy solutions. Aiming to understand the complex conversion process between radiative, electrical and thermal energies within TPVs, a multi-physics coupled model is established. From the heat generation, temperature and carrier perspectives, the output performance is analyzed in detail. Under 1200 K black-body radiation, the energy loss distribution in the GaSb cell is analyzed meticulously, where Joule heat (40.4 %), surface recombination heat (23.1 %) and thermalization heat (20.8 %) play predominant roles. As it stands, the cell temperature rises to a maximum of 317.0 K with a cooling intensity of 300 W/(m2·K). The minimum of the average cell temperature (approximately 312.3 K) occurs at the optimized working voltage of 0.3 V. Subsequently, the electrical characteristics are illustrated. The results indicate a maximum output power underestimation of 4.6 % compared to the uncoupled isothermal case. Based on the coupled model, a quantitative analysis of the anti-reflection coating (ARC), the structural adjustment (SA) and the selective emitter (SE) is conducted. The results reveal that the ARC case exhibits the most enhancement in the output power (55.3 %) followed by the SA case, which effectively improves it by 12.2 %. Although the SE case partially decreases the output power (−9.8 %), it shows promise in promoting conversion efficiency. Integrating the above strategies, the TPV system achieves an impressive conversion efficiency of 29.38 %, representing a 76.46 % improvement compared to the prototype with the cell only

Highly efficient molybdenum nanostructures for solar thermophotovoltaic systems: One-step fabrication of absorber and design of selective emitter

Efficient solar energy harvesting materials or structures have become a topic of great interest in response to the ever-increasing energy demand. Refractory transition metals have been found to exhibit attractive properties in broadband absorptance, making them highly effective in solar thermophotovoltaic (STPV) systems that aim to surpass the Shockley-Queisser limit. Typically, broadband absorbers are made from hybrid materials or complex geometrical structures, which require multi-step fabrication technologies. In this study, we successfully developed a highly efficient broadband absorber based on molybdenum (Mo) nanosheets using a one-step physical vapor deposition process. The nanosheets result in the high absorber efficiencies of 96.1 % for blackbody radiation (BBR) at 5778 K and of 96.4 % for air mass (AM) 1.5 spectrum, and are insensitive to polarization and incident angle. After annealing at 1650 K for 24 h, the Mo nanosheets absorber demonstrates outstanding thermal stability without compromising the efficiency of the STPV system. To complete the STPV system, a selective narrowband Mo-based gratings emitter was further designed with a high emissivity of 96 % at a wavelength of 2.17 μm, resulting in a high PV cell efficiency of 41.8 % around 1723 K. Through a series of theoretical calculations, the proposed STPV system can achieve an overall conversion efficiency of 40.2 % by a trade-off between the structure temperature and the sun concentration. Furthermore, an efficiency of 35.5 % can be achieved at a low temperature of 1073 K with a low solar concentration of 500 suns.The results provide tremendous opportunities for widespread applications of high-performance STPV systems.

Three-dimensional shape measurement technique for hot and shiny forging

For hot and shiny forging, rapid optical three-dimensional (3D) shape measurement can find the defects in time, improve manufacturing efficiency and reduce manufacturing cost. Optical 3D measurement of hot and shiny forging faces following three challenges. (a) Influence of blackbody radiation on the red band of visible light leads to saturation of captured fringe pattern. (b) Infrared band of blackbody radiation causes the camera to heat up. (c) Specular reflection of shiny forging leads to local saturation of captured fringe pattern. To address the above issues, we propose an effective optical 3D measurement scheme for hot and shiny forging in this paper. Firstly, the experiments demonstrate that the influence of blackbody radiation on visible light is concentrated in red light band and has no crosstalk in the blue light band, so we adopt blue light projection and blue light band-pass filter (BBF) to capture clear fringe pattern. Secondly, since the BBF cannot block the near-infrared component, we use an infrared light cutoff filter (ICF) to reduce the thermal effect of blackbody radiation. Finally, we analyze the Fourier transform (FT) spectrum of saturated fringe pattern caused by specular reflection, and propose an efficient Butterworth low-pass filtering (BLPF) method that does not require additional hardware, algorithm processing, and image assistance. The experimental results verify the effectiveness of the proposed scheme.

SootImage: An image recreation, post-processing validation procedure for sooting axisymmetric flames

Validation is a vital part of any computational fluid dynamics study. Validation is done by comparing the computed results to the experimental measurements performed in a known configuration. In sooting flames, such a comparison is non-trivial since the measurements have a wide range of uncertainty due to difficulties in directly measuring soot volume fractions. This work introduces a different way to verify the computations using a software package called SootImage. In this proposed methodology, comparisons are not made directly to the computed properties of interest (soot volume fraction and temperature). Instead, a post-processing procedure is performed to obtain an image of the flame based on the computed properties. This reconstructed image is compared to an actual image of the flame being studied. The algorithm of the image reconstruction utilized within SootImage is presented in detail. Finally, the usage of SootImage is demonstrated on a co-flowing, laminar ethylene/air diffusion flame. Program summaryProgram Title: SootImageCPC Library link to program files:https://doi.org/10.17632/nc5myw64km.1Developer's repository link:https://github.com/VictorChernov/SootImageLicensing provisions: CC BY NC 3.0Programming language: MATLABNature of problem: The software allows comparing images of a real flame with the recreated image of a simulated flame. This requires two major steps. One is the recreation of the image of an axisymmetrical flame from the computed soot volume fraction and temperature fields for a known camera and optical configuration. The second is cropping and position images to obtain a meaningful comparison.Solution method: The solution recreates the image by integrating the soot thermal radiation over a line-of-sight. Soot is assumed to emit as gray body. The integrated radiation is passed through the color filters of the camera and is translated to pixel values. After the process is done for the whole flame, the width, height and origin of both flames are found, and images that can be easily compared are created.

Metallic photoluminescence of plasmonic nanoparticles in both weak and strong excitation regimes

Abstract The luminescent nature of plasmonic nanoparticles (NPs) has been intensively investigated in recent years. Plasmon-enhanced electronic Raman scattering and the radiation channels of metallic photoluminescence (PL) involving conventional carrier recombinations and emergent particle plasmons are proposed in the past few decades but largely limited to weak excitation regimes. Here, we systematically examine the PL evolution of plasmonic NPs under different excitation power levels. The spectral resonances and chromaticity of PL are investigated within and beyond the scope of geometry conservation. Results indicate the nature of PL in plasmonic NPs could be a process of graybody radiation, including one factor of plasmonic emissivity in the weak excitation regime and the other factor of blackbody radiation in the strong excitation regime. This comprehensive analysis provides a fundamental understanding of the luminescent nature of plasmonic NPs and highlights their potential applications in transient temperature detection at the nanometer scale.

Emission Spectroscopy-Based Sensor System to Correlate the In-Cylinder Combustion Temperature of a Diesel Engine to NOx Emissions.

Due to a rising importance of the reduction of pollutant, produced by conventional energy technologies, the knowledge of pollutant forming processes during a combustion is of great interest. In this study the in-cylinder temperature, of a near series diesel engine, is examined with a minimal invasive emission spectroscopy sensor. The soot, nearly a black body radiator, emits light, which is spectrally detected and evaluated with a modified function of Planck's law. The results show a good correlation between the determined temperatures and the NOx concentration, measured in the exhaust gas of the engine, during a variety of engine operating points. A standard deviation between 25 K and 49 K was obtained for the in-cylinder temperature measurements.

An experimental platform for investigation of the Zeeman effect in strong magnetic fields.

An experimental platform is developed for the investigation of the Zeeman effect in strong magnetic fields. Mega-Gauss magnetic fields are generated by a 1 MA Zebra pulsed power machine using metal rod loads. A gas jet or CH oil on the load is the source of hydrogen. Excited hydrogen atoms are backlit by black body radiation from the rod load. Hydrogen absorption spectra are recorded with a grating spectrometer and intensified gated CCD camera. The experimental platform enables the observation of the quadratic Zeeman effect in hydrogen gas jets using the spectral shift of the central line in the Zeeman triplet. Other gases can be studied using the gas jet method.

Pixelwise high-temperature calibration for in-situ temperature measuring in powder bed fusion of metal with laser beam

High-temperature calibration methods in additive manufacturing involve the use of advanced techniques to accurately measure and control the temperature of the build material during the additive manufacturing process. Infrared cameras, blackbody radiation sources and non-linear optimization algorithms are used to correlate the temperature of the material with its emitted thermal radiation. This is essential for ensuring the quality and repeatability of the final product. This paper presents the calibration procedure of an imaging system for in-situ measurement of absolute temperatures and temperature gradients during powder bed fusion of metal with laser beam (PBF-LB/M) in the temperature range of 500 K–1500 K. It describes the design of the optical setup to meet specific requirements in this application area as well as the procedure for accounting the various factors influencing the temperature measurement. These include camera-specific effects such as varying spectral sensitivities of the individual pixels of the sensor as well as influences of the exposure time and the exposed sensor area. Furthermore, influences caused by the complex optical path, such as inhomogeneous transmission properties of the galvanometer scanner as well as angle-dependent transmission properties of the f-theta lens were considered. A two-step fitting algorithm based on Planck's law of radiation was applied to best represent the correlation. With the presented procedure the calibrated thermography system provides the ability to measure absolute temperatures under real process conditions with high accuracy.

Measurement of infrared magic wavelength for an all-optical trapping of 40Ca+ ion clock

For the first time, we experimentally determine the infrared magic wavelength for the 40Ca+ 4s2S1/2→3d2D5/2 electric quadrupole transition by observation of the light shift canceling in 40Ca+ optical clock. A ‘magic’ magnetic field direction is chosen to make the magic wavelength insensitive to both the linear polarization purity and the polarization direction of the laser. The determined magic wavelength for this transition is 1056.37(9) nm, which is not only in good agreement with theoretical predictions (‘Dirac–Fock plus core polarization’ method) but also more precise by a factor of about 300. Using this measured magic wavelength, we also derive the differential static polarizability to be −44.32(32) a.u., which will be an important input for the evaluation of the blackbody radiation shift at room temperatures. Our work paves a way for all-optical-trapping of 40Ca+ optical clock.

Evidence of the γ-ray counterpart of nova FM Cir from Fermi–LAT

ABSTRACT We report the results of an analysis of X-ray and γ-ray data from the nova FM Cir taken by Swift and Fermi–LAT. The γ-ray emission from FM Cir can be identified with a significance level of ∼3σ within ∼40 d after the nova eruption (2018 January 19) when we bin the light curve per day. The significance can exceed the 4σ confidence level if we accumulate a longer time (i.e. 20 d) to bin the light curve. The γ-ray counterpart could be identified with a Test Statistic (TS) above 4 until ∼180 d after the eruption. The duration of the γ-ray detection is longer than those reported in previous studies of other novae detected in the GeV range. Significant X-ray emission was observed after the γ-ray flux level fell below the sensitivity limit of Fermi–LAT. The hardness ratio of the X-ray emission decreased rapidly with time, and the spectra were dominated by blackbody radiation from the hot white dwarf. Except for the longer duration of the γ-ray emission, the multiwavelength properties of FM Cir closely resemble those of other novae detected in the GeV range.

Multispectral Thermometry Method Based on Optimisation Ideas.

Multispectral thermometry is based on the law of blackbody radiation and is widely used in engineering practice today. Temperature values can be inferred from radiation intensity and multiple sets of wavelengths. Multispectral thermometry eliminates the requirements for single-spectral and spectral similarity, which are associated with two-colour thermometry. In the process of multispectral temperature inversion, the solution of spectral emissivity and multispectral data processing can be seen as the keys to accurate thermometry. At present, spectral emissivity is most commonly estimated using assumption models. When an assumption model closely matches an actual situation, the inversion of the temperature and the accuracy of spectral emissivity are both very high; however, when the two are not closely matched, the inversion result is very different from the actual situation. Assumption models of spectral emissivity exhibit drawbacks when used for thermometry of a complex material, or any material whose properties dynamically change during a combustion process. To address the above problems, in the present study, we developed a multispectral thermometry method based on optimisation ideas. This method involves analysing connections between measured temperatures of each channel in a multispectral temperature inversion process; it also makes use of correlations between multispectral signals at different temperatures. In short, we established a multivariate temperature difference correlation function based on the principles of multispectral radiometric thermometry, using information correlations between data for each channel in a temperature inversion process. We then established a high-precision thermometry model by optimising the correlation function and correcting any measurement errors. This method simplifies the modelling process so that it becomes an optimisation problem of the temperature difference function. This also removes the need to assume the relationships between spectral emissivity and other physical quantities, simplifying the process of multispectral thermometry. Finally, this involves correction of the spectral data so that any impact of measurement error on the thermometry is reduced. In order to verify the feasibility and reliability of the method, a simple eight-channel multispectral thermometry device was used for experimental validation, in which the temperature emitted from a blackbody furnace was identified as the standard value. In addition, spectral data from the 468-603 nm band were calibrated within a temperature range of 1923.15-2273.15 K, resulting in multispectral thermometry based on optimisation principles with an error rate of around 0.3% and a temperature calculation time of less than 3 s. The achieved level of inversion accuracy was better than that obtained using either a secondary measurement method (SMM) or a neural network method, and the calculation speed achieved was considerably faster than that obtained using the SMM method.

Bias-Tunable Quantum Well Infrared Photodetector.

With the rapid advancement of Artificial Intelligence-driven object recognition, the development of cognitive tunable imaging sensors has become a critically important field. In this paper, we demonstrate an infrared (IR) sensor with spectral tunability controlled by the applied bias between the long-wave and mid-wave IR spectral regions. The sensor is a Quantum Well Infrared Photodetector (QWIP) containing asymmetrically doped double QWs where the external electric field alters the electron population in the wells and hence spectral responsivity. The design rules are obtained by calculating the electronic transition energies for symmetric and antisymmetric double-QW states using a Schrödinger-Poisson solver. The sensor is grown and characterized aiming detection in mid-wave (~5 µm) to long-wave IR (~8 µm) spectral ranges. The structure is grown using molecular beam epitaxy (MBE) and contains 25 periods of coupled double GaAs QWs and Al0.38Ga0.62As barriers. One of the QWs in the pair is modulation-doped to provide asymmetry in potential. The QWIPs are tested with blackbody radiation and FTIR down to 77 K. As a result, the ratio of the responsivities of the two bands at about 5.5 and 8 µm is controlled over an order of magnitude demonstrating tunability between MWIR and LWIR spectral regions. Separate experiments using parameterized image transformations of wideband LWIR imagery are performed to lay the framework for utilizing tunable QWIP sensors in object recognition applications.

The minimum mass for star formation by dynamical fragmentation: dependence on epoch, dust abundance, and environment

ABSTRACT We estimate the minimum mass of a star formed by dynamical collapse and fragmentation, as a function of epoch, dust abundance, and environment. Epoch is parametrized by redshift, zred, through the variation in the temperature of the cosmic microwave background. The dust abundance is parametrized by the mass-fraction in dust, ZD, with the additional simplifying assumption that the intrinsic properties of dust do not change with ZD, only the amount of dust. Environment is parametrized by the energy-density of the ambient suprathermal radiation fields through a dilution factor ω⋆ (applied to a blackbody radiation field at $T_{\star }=10^4\, {\rm K}$). The critical condition is that a spherical proto-fragment should be able to cool, and therefore contract, fast enough to detach from neighbouring proto-fragments. The minimum mass increases with increasing redshift, increasing dust abundance, and increasing suprathermal background. Values in the range from $M_{{\rm MIN}}\sim 0.002\, {\rm M}_{\odot }$ to $M_{{\rm MIN}}\sim 0.2\, {\rm M}_{\odot }$ are obtained at the extremes of the parameter ranges we have considered (0 ≤ zred ≤ 8,  0.00016 < ZD < 0.04,  and  10−15 ≤ ω⋆ ≤ 10−8). Our results agree quite well with the predictions of detailed numerical simulations invoking similar redshifts and dust abundances, but our estimates are somewhat lower; we attribute this difference to resolution issues and the small-number statistics from the simulations. The increased minimum masses predicted at high redshift and/or high suprathermal background result in significantly bottom-light initial mass functions, and therefore low mass-to-light ratios, provided that the dust abundance is not too low. The changes due to high suprathermal background may be particularly important for star formation in galactic nuclei and at high redshift.

The Puzzling of Stefan–Boltzmann Law: Classical or Quantum Physics

Stefan–Boltzmann law, stating the fourth power temperature dependence of the radiation emission by a black-body, was empirically formulated by Stefan in 1874 by fitting existing experiments and theoretically validated by Boltzmann in 1884 on the basis of a classical physical model involving thermodynamics principles and the radiation pressure predicted by Maxwell equations. At first sight the electromagnetic (EM) gas assumed by Boltzmann and following Rayleigh (1900) identifiable as an ensemble of N classical normal-modes, looks like an extension of the classical model of the massive ideal-gas. Accordingly, for this EM gas the internal total energy, U, was assumed to be function of volume V and temperature T as [Formula: see text], and the equation of state was given by [Formula: see text], with P the radiation pressure. In addition, Boltzmann implicitly assumed that, for given values of V and T, U and the number of modes N would take finite values. However, from one hand these assumptions are not justified by Maxwell equations and classical statistics since, in vacuum (i.e., far from the EM sources), the values of N and U diverge, the so-called ultraviolet catastrophe introduced by Ehrenfest in 1911. From another hand, Boltzmann derivation of Stefan law is found to be macroscopically compatible with its derivation from quantum statistics announced by Planck in 1901. In this paper, we present a justification of this puzzling classical/quantum compatibility by noticing that the implicit assumptions made by Boltzmann is fully justified by Planck quantum statistics. Furthermore, we shed new light on the interpretation of recent classical simulations of a black body carried out by Wang, Casati, and Benenti in 2022 who found an analogous puzzling consistency between Stefan–Boltzmann law and their simulations to induce speculations on classical physics and black body radiation that are claimed to require a critical reconsideration of the role of classical physics for the understanding of quantum mechanics.

Temperature-Automated Calibration Methods for a Large-Area Blackbody Radiation Source.

High-precision temperature control of large-area blackbodies has a pivotal role in temperature calibration and thermal imaging correction. Meanwhile, it is necessary to correct the temperature difference between the radiating (surface of use) and back surfaces (where the temperature sensor is installed) of the blackbody during the testing phase. Moreover, large-area blackbodies are usually composed of multiple temperature control channels, and manual correction in this scenario is error-prone and inefficient. At present, there is no method that can achieve temperature-automated calibration for a large-area blackbody radiation source. Therefore, this article is dedicated to achieving temperature-automated calibration for a large-area blackbody radiation source. First, utilizing two calibrated infrared thermometers, the optimal temperature measurement location was determined using a focusing algorithm. Then, a three-axis movement system was used to obtain the true temperature at the same measurement location on a large-area blackbody surface from different channels. This temperature was subtracted from the blackbody's back surface. The temperature difference was calculated employing a weighted algorithm to derive the parameters for calibration. Finally, regarding experimental verification, the consistency error of the temperature measurement point was reduced by 85.4%, the temperature uniformity of the surface source was improved by 40.4%, and the average temperature measurement deviation decreased by 43.8%. In addition, this system demonstrated the characteristics of strong environmental adaptability that was able to perform temperature calibration under the working conditions of a blackbody surface temperature from 100 K to 573 K, which decreased the calibration time by 9.82 times.

Utilizing blackbody radiation inversion to attain an upper bound on the mass of photon using cosmic microwave background radiation

Utilizing blackbody radiation inversion to attain an upper bound on the mass of photon using cosmic microwave background radiation

Toward a dual-species atom interferometer with cadmium and strontium

We report on the progress toward a dual-species cadmium and strontium atom interferometer for fundamental physics tests. We have developed and characterized a complete baseline laser system for cadmium, which provides the high power and narrow linewidth necessary for laser cooling and trapping and for performing atom interferometry, with upgraded systems for strontium also implemented. An overview of a design for cooling cadmium is presented, and we outline the basic design of a Cd–Sr atomic fountain, discussing atom launching techniques and the possible role of blackbody radiation. The excellent properties of cadmium and strontium, both individually and as a test pair, are discussed along with the enabled fundamental physics program of tests of the weak equivalence principle and the measurement of relativistic time dilation effects in quantum superpositions of clocks.

Dulong-Petit’s law and Boltzmann’s theoretical proof from the Kinetic Theory of Gases

The main aspect that we will address in this work is the introductory presentation of the empirical law of the specific heats of material bodies, published by Dulong and Petit on April 12, 1819, in the magazine Comptes Rendus. The analytical demonstration of this law appeared for the first time in 1866 in the Doctoral Thesis of the Austrian physicist Ludwig Boltzmann, according to the research carried out by Cássio C. Laranjeiras and presented in his Doctoral Thesis in 2002. In the introduction we discussed how Dulong’s law and Petit played a key role in the subsequent development of a new physics (Quantum Mechanics), when Max Planck changed his research program from electrodynamics to thermodynamics, evidenced in the book: Black Body Theory and the Quantum Discontinuity, 1894-1912, published by Thomas Khun in 1978. Between 1900 and 1912, we observed that fundamental works published by Albert Einstein, Henri Poincaré and Peter Debye explained the mathematical relationship of this empirical law based on Planck’s hypothesis of the quantum of action of blackbody radiation. Despite the controversy over the authorship of the law, whether it would have been formulated in advance by Arago, we agree with Robert Fox that it was the results of Dulong and Petit’s experiments that led to the formulation of the law.