Conversion Efficiency Of Radiation Research Articles

Ideal Photothermal Materials Based on Ge Subwavelength Structure.

Photothermal materials often prioritize solar absorption while neglecting thermal radiation losses, which diminishes thermal radiation conversion efficiency. This study addresses this gap by introducing a germanium (Ge) subwavelength structure (SWS) designed to optimize both solar absorption and infrared emissivity. Using a self-masked reactive ion etching (RIE) technique, we achieved a peak absorption of 98.8% within the 300 nm to 1800 nm range, with an infrared emissivity as low as 0.32. Under solar illumination of 1000 W/m2, the structure's temperature increased by 50 °C, generating a heating power of 800 W/m2. Additionally, it demonstrated good mechanical and thermal stability at high temperatures and possessed a hydrophobic angle of 132°, ensuring effective self-cleaning. These characteristics make the Ge SWS suitable for application in solar panels, displays, sensors, and other optoelectronic devices.

Quantitative Structure Photovoltaic Properties Relationship of Coumarin Dyes Derived

The performance of an organic solar cell is strongly influenced by the structure of the photosensitizer. In this work, the open-circuit voltage (<I>V<SUB>OC</SUB></I>) and conversion efficiency (<i>η</i>) of a series of coumarin dyes are quantitatively related to the structure of nine coumarin derivatives. The Quantitative Structure Property Relationship (QSPR) is performed using the statistical method of multiple linear regression. In addition, descriptors determined from the ground state at the Cam_B3lyp/6-31G(d, p) level of theory and from the 2D structure of the molecules are mathematically related to the photovoltaic properties. These VOC and <i>η </i>models are accredited with very good statistical indicators (<I>R<sup>2</sup></I> = 0.906 and 0.918; Q<sub>cv</sub><sup>2</sup>= 0.845 and 0.849; S= 0.045 and 0.112; F = 14.524 and 16.846). These statistical indicators confirm the robustness and performance of the models developed. The results show that Voc improves with decreasing surface tension (<i>ts</i>) and increasing number of cycles (<i>cycle</i>). As for the conversion efficiency of light radiation into electrical energy, it is optimal when the light harvesting efficiency (<i>LHE<sub>th</sub></i>) and the excited state lifetime (<i>τ<sub>th</sub></i>) are high. In conclusion, these models have good predictive capabilities and can be used to predict and explain the open-circuit voltage and efficiency of coumarin derivatives that belong to the same field of application.

Enhanced terahertz radiation generated by intense laser interaction with a two-layer thin solid target

A terahertz radiation enhancing scheme, in which a linearly polarized weakly relativistic laser pulse irradiates a target consisting of two parallel thin-solid layers with a certain gap, is proposed and studied by using two-dimensional particle-in-cell simulations. The radiation is known to be produced by laser-produced hot electrons via mechanisms such as coherent transition radiation at the target surfaces. Under optimized conditions, the energy conversion efficiency of terahertz radiation can be as high as 3.3%, which is nearly 1.5 times higher than that obtained with a single-layer target with the same drive laser. This is mainly due to the enhanced hot electron generation with moderate energy via multiple reflections of the laser pulse between the two target layers. The radiation has two peaks close to 30° from the target surface, which are more collimated than that with the single-layer target. The dependence of the terahertz radiation on a variety of target parameters is given, which can control the terahertz spectrum and radiation efficiency and thus provide guidance for experimental investigations. Moreover, both the coherent transition radiation and antenna radiation models are applied to explain the angular distributions of the terahertz emission found in the simulations. Published by the American Physical Society 2024

Carbon Nanotube Films with Fewer Impurities and Higher Conductivity from Aqueously Mono-Dispersed Solution via Two-Step Filtration for Electric Heating.

With the intensification of global climate problems, electric heating has recently attracted much attention as a clean and low-carbon heating method. Carbon nanotubes (CNTs) are an ideal medium for electric heating applications due to their excellent mechanical, electrical, and thermal properties. The preparation of electrothermal films based on an aqueous CNT dispersion as a raw material is environmentally friendly. However, in the traditional one-step filtration method, the residual excess dispersant and the small aspect ratio of the CNTs in the preparation process limit the performance of electrothermal CNT films. In this paper, we report a two-step filtration method that removes the free dispersant and small CNTs in the first filtration step and obtains denser CNT films by controlling the pores of the filter membrane in the second filtration step. The results suggest that, compared to the CNT1 film obtained from one-step filtration, the CNT1-0.22 film, obtained from two-step filtration using 1 and 0.22 μm membranes, has a smoother and flatter surface, and the surface resistance is 80.0 Ω sq-1, which is 29.4% lower. The convective radiation conversion efficiency of the CNT1-0.22 film is 3.36 mW/°C, which is 36.1% lower. We anticipate that such CNT films could be widely applied in building thermal insulation and underfloor heating.

Adaptive cooling strategy via human hair: High optothermal conversion efficiency of solar radiation into thermal dissipation

Natural species have developed complex nanostructures in a hierarchical pattern to control the absorption, reflection, or transmission of desired solar and infrared wavelengths. This bio-inspired structure is a promising method to manipulating solar energy and thermal management. In particular, human hair is used in this article to highlight the optothermal properties of bio-inspired structures. This study investigated how melanin, an effective solar absorber, and the structural morphology of aligned domains of keratin polymer chains, leading to a significant increase in solar path length, which effectively scatter and absorb solar radiation across the hair structure, as well as enhance thermal ramifications from solar absorption by fitting its radiative wavelength to atmospheric transmittance for high-yield radiative cooling with realistic human body thermal emission.

Simulation of extreme ultraviolet radiation of laser induced discharge plasma

Extreme ultraviolet (EUV) light source is an important part of EUV lithography system in semiconductor manufacturing. The EUV light source requires that the 4p<sup>6</sup>4d<sup><i>n</i></sup>-4p<sup>5</sup>4d<sup><i>n</i>+1</sup> + 4d<sup><i>n</i>-1</sup>4f transitions of Sn<sup>8+~13+</sup> ions emit thousands of lines which form unresolved transition arrays near 13.5 nm. Laser-induced discharge plasma is one of the important technical means to excite target into an appropriate plasma condition. Laser-induced discharge plasma has a simple structure and a low cost. It also has important applications in mask inspection, microscopic imaging, and spectral metrology. In the design and production process, there are many factors that can influence the conversion efficiency, such as current, electrode shape, and laser power density. The simulation method is a convenient way to provide guidance for optimizing the parameters. In this paper, a completed radiation magneto-hydrodynamic model is used to explore the dynamic characteristics of laser-induced discharge plasma and its EUV radiation characteristics. To improve the accuracy, a more detailed global equation of state model, an atomic structure calculation model including relativistic effect and a collision radiation model are proposed simultaneously. The simulation reconstructs the discharge process effectively, which is divided into five stages in the first half cycle of current, including expansion of laser plasma, column formation of discharge plasma, diffusion of discharge plasma, contraction of discharge plasma, and re-diffusion of discharge plasma. It is revealed that the pinch effect during the current rising time exerts a significant influence on the generation of EUV radiation. The conversion efficiency of EUV radiation is still low under our existing conditions, and hopefully a higher rising rate of current can improve the conversion efficiency in the future work.

On the Efficiency of Solar Radiation Conversion into Steam, Production of Clean Water, and Generation of Electrical Energy

This study focuses on the development of a model for evaluating the efficiency of converting solar radiation into thermal energy. The efficiency coefficient is represented as a function of multiple variables, including system geometry, time, properties of the working fluid, and external parameters. The developed model is a simplified version and is applicable to systems with a stationary working fluid undergoing heating and vaporization due to solar radiation. Calculations were performed based on the model using a gold-water nanofluid. The results of the calculations demonstrated the existence of an optimal range of optical thickness and nanoparticle concentration, where the working fluid is effectively heated and vaporized. It is shown that the efficiency of systems employing nanofluids as heat transfer fluids cannot be evaluated solely based on the absolute value of the heating efficiency coefficient. However, it can be assessed through its derivative with respect to time. The faster the heating efficiency coefficient decreases over time, the more efficient the system is in terms of heating, and the sooner it reaches a steady-state condition. The developed model serves as a foundation for the advancement of more sophisticated models that allow for the evaluation of various other factors, such as complex geometries with forced fluid flow, the nature of interactions between nanoparticles and the base fluid, as well as mechanisms of solar radiation conversion into thermal energy.

Sustainable microwave-heating healing asphalt concrete fabricated with waste microwave-sensitive fillers

The use of waste fillers as substitutes for limestone powder (LP) filler is a promising way to consume industrial by-products and achieve sustainable asphalt pavement. This study recycles three types of microwave-sensitive fillers, namely, coal gangue powder (CGP), ferrite powder (FP), and fly ash (FA), as alternatives to LP filler, in the creation of microwave-heating healing asphalt composites. The results indicate that conventional LP-modified asphalt mastics have a self-healing initiation temperature of 88.2 °C. On the contrary, CGP-modified asphalt mastics and FP-modified asphalt mastics exhibit significantly lower starting self-healing temperatures, with values of 65.6 °C and 56.2 °C, respectively. Moreover, CGP-modified asphalt mastics and FP-modified asphalt mastics achieve an average surface temperature surpassing 95 °C within 60 s of microwave heating. It is worth noting that FP-modified asphalt mastics retain an impressive healing index of 46.6% even after three cycles of damage-healing-damage. The incorporation of microwave-sensitive fillers in asphalt composites can improve the conversion efficiency of microwave radiation to thermal energy, and thus enhance the microwave-heating healing characteristics compared to conventional LP-modified asphalt composites. Additionally, a comprehensive assessment of the environmental benefits and economic costs reveals significant cost savings and reductions in CO2 emissions associated with the adoption of microwave-heating healing asphalt pavement. These findings strongly support the practical implementation of microwave-sensitive fillers in asphalt composites, leading to improved maintenance efficiency, enhanced serviceability, and sustainability for pavement systems.

Experimental Study on the Temporal Evolution Parameters of Laser–Produced Tin Plasma under Different Laser Pulse Energies for LPP–EUV Source

The laser–produced plasma extreme ultraviolet (LPP–EUV) source is the sole light source currently available for commercial EUVL (extreme ultraviolet lithography) machines. The plasma parameters, such as the electron temperature and electron density, affect the conversion efficiency (CE) of extreme ultraviolet radiation and other critical parameters of LPP–EUV source directly. In this paper, the optical emission spectroscopy (OES) was employed to investigate the time–resolved plasma parameters generated by an Nd:YAG laser irradiation on a planar tin target. Assuming that the laser–produced tin plasma satisfies the local thermodynamic equilibrium (LTE) condition, the electron temperature and electron density of the plasma were calculated by the Saha–Boltzmann plot and Stark broadening methods. The experimental results revealed that during the early stage of plasma formation (delay time < 50 ns), there was a significant presence of continuum emission. Subsequently, the intensity of the continuum emission gradually decreased, while line spectra emerged and became predominant at a delay time of 300 ns. In addition, the evolution trend of plasma parameters, with the incident laser pulse energy set at 300 mJ, was characterized by a rapid initial decrease followed by a gradual decline as the delay time increased. Furthermore, with an increase in the incident laser pulse energy from 300 mJ to 750 mJ, the electron temperature and electron density of laser–produced tin plasma exhibiting a monotonically showed increasing trend at the same delay time.

Passive Energy Conservation Strategies for Mitigating Energy Consumption and Reducing CO2 Emissions in Traditional Dwellings of Peking Area, China

Within China, brick dwellings stand as archetypal relics of traditional habitation, embodying a “living fossil” status. The sustainability of these dwellings is contingent upon the integration of energy-conservation strategies. This study scrutinized and empirically assessed a representative dwelling in the Peking area. Using numerical simulations, the impact on energy consumption of factors such as insulation and glazing type, external wall thickness, insulation thickness, and solar energy utilization was evaluated. The outcomes reveal that introducing external thermal insulation—specifically, expanded polystyrene panels with a thickness of 60 mm and 40 mm for the roof and exterior walls, respectively—along with a sunspace of depth 1.5 m yielded superior energy efficiency. Additionally, substituting conventional roofing with solar tiles exhibited a potential annual electricity generation coupled with an annual solar radiation conversion efficiency of 17%. Collectively, these strategies induced a substantial reduction in annual energy consumption. This study presents tailored energy-conservation measures and provides design decision support for architects’ practical recommendations on thermal environment control of passive traditional dwellings in the Peking area.

Soybean seed yield and protein response to crop rotation and fertilization strategies in previous seasons

Annual crops dominate Argentinean landscapes with a majority of fields dedicated to soybean production. Consecutive years with full-season soybean crops are frequent and this practice is associated with organic carbon losses affecting soil chemical and physical properties. It is proposed that more intensive and diverse cropping sequences coupled with targeted fertilization may allow keeping near-neutral nutrient and carbon balances while improving successive crops performance. We conducted four on–farm experiments along six seasons in the Argentine Pampas where three crop rotations and two fertilization strategies (high and regular rates of N, P, and S) were evaluated. Crop rotations involved were i) soybean monoculture, ii) a typical wheat-soybean/maize/soybean rotation, and iii) a more intensified rotation consisting of wheat-soybean/field pea-maize/soybean. After five years, soil organic carbon was consistently lower under soybean monoculture compared to that under more intensive and diverse rotations. During the sixth and last season, identically managed soybean crops were grown in all treatments to determine the influence of previous management history on soil, plant nutrients, and on crop performance. Results indicate that crop rotation largely influenced soybean seed yield (range from 120 to 690 kg ha−1 yield increase) mainly through changes in water use affecting solar radiation interception and, by a lesser extent, the conversion efficiency of radiation into biomass and partition to seeds. Comparatively, increased fertilization rates in preceding seasons resulted in a lower seed yield response (range from nil to 180 kg ha−1), which indicates that fertilization strategies alone are ineffective to restore productivity levels after years of soybean monoculture. However, in most cases, the high fertilization strategy in previous seasons resulted in greater soybean protein concentration in seeds and in overall protein yield.

Betatron Radiation and Bremsstrahlung in the Interaction of Intense Laser Pulse with Solid Target

X-ray generation via synchrotron radiation and bremsstrahlung in the interaction of short laser pulses with a solid target is of much current interest owing to its numerous applications. The efficiency of laser to X-ray energy conversion is thus a crucial factor. We found that the energy conversion efficiency of synchrotron radiation and bremsstrahlung is mainly governed by the ratio of the laser pulse width to the preplasma width, which is in turn governed by the laser profile, intensity, and spot size. Synchrotron radiation dominates when the ratio is less than unity, otherwise bremsstrahlung dominates. The type of radiation can thus be controlled by tailoring the laser parameters.

On the Possibility of Converting Linearly Polarized Attosecond Pulses of High Harmonics into Circularly Polarized Pulses with an Increase in the Energy in an Optically Modulated Neon-Like Active Medium of an X-Ray Plasma Laser

A method is proposed for converting linearly polarized radiation of a single harmonic or a combination of high-order harmonics of an optical field, which form a train of subfemto-/attosecond pulses, into elliptically and, in particular, circularly polarized radiation in an optically modulated neon-like active medium of an X‑ray plasma laser. It is shown that this method can provide a high energy efficiency of radiation conversion due to the amplification of the harmonic field, and is also insensitive to changes in the number of high harmonics that form the amplified pulses. The possibility of experimental implementation of the method is considered on the example of an active plasma of neon-like Ti12+ ions with an unperturbed inverted transition wavelength of 32.6 nm.

РАСЧЕТ НЕЛИНЕЙНО-ОПТИЧЕСКИХ ХАРАКТЕРИСТИК КРИСТАЛЛОВ LiNbO3:Zn:Mg, ПОЛУЧЕННЫХ ПО ТЕХНОЛОГИЯМ ПРЯМОГО И ГОМОГЕННОГО ЛЕГИРОВАНИЯ

The coefficients of the second-order nonlinear optical tensor (dij) for lithium niobate crystals doubly doped with magnesium and zinc by different methods of impurity introduction were calculated.Impurity concentrations (Zn:Mg) in crystals were 3.74:1.09 mol. % in case of direct doping, 3.83:0.97 mol. % in case of homogeneous doping. It was shown that the efficiency of radiation conversion with second harmonic generation in a homogeneously doped crystal is higher than in a crystal obtained by the direct doping method.

Effects of a Graphene Heating Device on Fatigue Recovery of Biceps Brachii.

Far-infrared (FIR) is considered to be an ideal method to promote fatigue recovery due to its high permeability and strong radiation. In this paper, we report a flexible and wearable graphene heating device to help fatigue recovery of human exercise by using its high FIR divergence property. This study compares two different fatigue recovery methods, graphene far-infrared heating device hot application and natural recovery, over a 20 min recovery time among the male colleges' exhaustion exercise. Experimental results show that the achieved graphene device holds excellent electro-thermal radiation conversion efficiency of 70% and normal total emissivity of 89%. Moreover, the graphene FIR therapy in our work is more energy-efficient, easy to use, and wearable than traditional fatigue recovery methods. Such an anti-fatigue strategy offers new opportunities for enlarging potential applications of graphene film in body science, athletic training recovery, and wearable devices.

Broadband electromagnetic emission via mode conversion mediated by stimulated Raman scattering in inhomogeneous plasma

Electromagnetic emission via linear mode conversion from electron plasma waves (EPWs) excited by stimulated Raman scattering (SRS) of an incident laser pulse in inhomogeneous plasma is investigated theoretically and numerically. It is found that the mode conversion can occur naturally in underdense plasma region below the quarter critical density provided that EPWs are generated due to the development of backward SRS when the laser pulse is incident at certain angle with the plasma density gradient. The produced radiation may cover a broad frequency range up to half of the incident laser frequency. The dependence of the radiation conversion efficiency on the laser intensity, incident angle, laser pulse duration, plasma density scale length, and initial electron temperature is analyzed based on one-dimensional particle-in-cell simulation. In two-dimensional geometry, due to the development of sideward SRS, it is found that the mode conversion to occur even at normal incidence of the laser pulse. The radiation frequency, bandwidth, duration, and amplitude can be well controlled by the laser and plasma parameters, suggesting that it may provide a new source of tunable broadband radiation as well as a diagnosis of the development of SRS.

Novel Miscanthus hybrids: Modelling productivity on marginal land in Europe using dynamics of canopy development determined by light interception.

New biomass crop hybrids for bioeconomic expansion require yield projections to determine their potential for strategic land use planning in the face of global challenges. Our biomass growth simulation incorporates radiation interception and conversion efficiency. Models often use leaf area to predict interception which is demanding to determine accurately, so instead we use low-cost rapid light interception measurements using a simple laboratory-made line ceptometer and relate the dynamics of canopy closure to thermal time, and to measurements of biomass. We apply the model to project the European biomass potentials of new market-ready hybrids for 2020-2030. Field measurements are easier to collect, the calibration is seasonally dynamic and reduces influence of weather variation between field sites. The model obtained is conservative, being calibrated by crops of varying establishment and varying maturity on less productive (marginal) land. This results in conservative projections of miscanthus hybrids for 2020-2030 based on 10% land use conversion of the least (productive) grassland and arable for farm diversification, which show a European potential of 80.7-89.7Mt year-1 biomass, with potential for 1.2-1.3EJ year-1 energy and 36.3-40.3Mt year-1 carbon capture, with seeded Miscanthus sacchariflorus × sinensis displaying highest yield potential. Simulated biomass projections must be viewed in light of the field measurements on less productive land with high soil water deficits. We are attempting to model the results from an ambitious and novel project combining new hybrids across Europe with agronomy which has not been perfected on less productive sites. Nevertheless, at the time of energy sourcing issues, seed-propagated miscanthus hybrids for the upscaled provision of bioenergy offer an alternative source of renewable energy. If European countries provide incentives for growers to invest, seeded hybrids can improve product availability and biomass yields over the current commercial miscanthus variety.

Simulation of extreme ultraviolet radiation of laser induced discharge plasma

Extreme ultraviolet (EUV) light source is an important part of EUV lithography system in semiconductor manufacturing. The EUV light source requires that the 4p<sup>6</sup>4d<sup><i>n</i></sup>-4p<sup>5</sup>4d<sup><i>n</i>+1</sup> + 4d<sup><i>n</i>–1</sup>4f transitions of Sn<sup>8+~13+</sup> ions emit thousands of lines which form unresolved transition arrays near 13.5 nm. Laser-induced discharge plasma is one of the important technical means to excite target into an appropriate plasma condition. Laser-induced discharge plasma has a simple structure and a low cost. It also has important applications in mask inspection, microscopic imaging, and spectral metrology. In the design and production process, there are many factors that can influence the conversion efficiency, such as current, electrode shape, and laser power density. The simulation method is a convenient way to provide guidance for optimizing the parameters. In this paper, a completed radiation magneto-hydrodynamic model is used to explore the dynamic characteristics of laser-induced discharge plasma and its EUV radiation characteristics. To improve the accuracy, a more detailed global equation of state model, an atomic structure calculation model including relativistic effect and a collision radiation model are proposed simultaneously. The simulation reconstructs the discharge process effectively, which is divided into five stages in the first half cycle of current, including expansion of laser plasma, column formation of discharge plasma, diffusion of discharge plasma, contraction of discharge plasma, and re-diffusion of discharge plasma. It is revealed that the pinch effect during the current rising time exerts a significant influence on the generation of EUV radiation. The conversion efficiency of EUV radiation is still low under our existing conditions, and hopefully a higher rising rate of current can improve the conversion efficiency in the future work.

Нелинейно-оптические свойства кристаллов ниобата лития, легированных цинком

The coefficients of the second order nonlinear optical dij tensor were calculated by the method developed on the basis of the dielectrics theory of Phillipson and Van Wetchen and the Levin charge coupling model for lithium niobate crystals doped with zinc (3.43–5.84 mol %). In LiNbO3 : Zn crystals, the concentration dependences of the nonlinear optical coefficients showed several regions with maxima and minima; the most noticeable changes in the nonlinear optical coefficients were observed at threshold concentrations of zinc oxide in the melt. Doping with zinc increases the conversion efficiency of the second harmonic radiation, such the crystals are more promising for use in nonlinear optics than a nominally pure lithium niobate crystal.

Control of second-harmonic generation in all-dielectric intersubband metasurfaces by controlling the polarity of χ(2).

All-dielectric metasurfaces have recently led to a paradigm shift in nonlinear optics as they allow for circumventing the phase matching constraints of bulk crystals and offer high nonlinear conversion efficiencies when normalized by the light-matter interaction volume. Unlike bulk crystals, in all-dielectric metasurfaces nonlinear conversion efficiencies primarily rely on the material nonlinearity, field enhancements, and the modal overlaps, therefore most efforts to date have only focused on utilizing these degrees of freedom. In this work, we demonstrate that for second-harmonic generation in all-dielectric metasurfaces, an additional degree of freedom is the control of the polarity of the nonlinear susceptibility. We demonstrate that semiconductor heterostructures that support resonant nonlinearities based on quantum-engineered intersubband transitions provide this new degree of freedom. We can flip and control the polarity of the nonlinear susceptibility of the dielectric medium along the growth direction and couple it to the Mie-type photonic modes. Here we demonstrate that engineering the χ(2) polarity in the meta-atom enables the control of the second-harmonic radiation pattern and conversion efficiency. Our results therefore open a new direction for engineering and optimizing second-harmonic generation using all-dielectric intersubband nonlinear metasurfaces.