Radiation Asymmetry Research Articles

Joint Analysis of Solar Radiation and Wind Speed: Approach With Sliding Windows

Objective: This paper aims to characterise the daily fluctuations of the wind speed and solar radiation time series of some cities in the State of Bahia, Brazil, from January 2009 to December 2018, using the sliding window approach. Theoretical Framework: Due to its complexity and importance for life on planet Earth, climate change and its socio-environmental impacts are subject to studies by the scientific community and governmental and non-governmental institutions. Wind speed and solar radiation are among the elements that are relevant to climate change. Method: The DCCA Cross-Correlation Coefficient (ρDCCA) was applied to meet the objective. Five cities in Bahia, with different biomes, were selected for the modelling. Results and Discussion: The descriptive one with sliding windows identified a predominance of greater relative variation around the mean in the solar radiation time series and divergent signs in the asymmetry of wind speed and solar radiation. It was found in the cross-correlation estimation, via ρDCCA, positive and negative correlations varying according to the city, the size of the window (w) and the evaluated temporal scale (n). Conclusion: From the results and chosen methodology, one more proposal to jointly and dynamically characterise the climatic variables wind speed and solar radiation fluctuations is presented.

Radiation asymmetry in JET disruption mitigation experiments with shattered pellet injection

In ITER, to mitigate the deleterious effects of plasma disruptions, massive quantities of radiating impurities will be injected into the disrupting plasma by shattered pellet injectors (SPI) to pre-emptively radiate away the stored thermal and magnetic energy (Lehnen et al Proc. 27th IAEA Fusion Energy Conf. (FEC 2018) (Gandhinagar, India) EX/P7-12). However, asymmetries in the radiation pattern could result in intense photon flashes during the thermal quench that could locally damage or erode the stainless steel plasma-facing surface of the diagnostic port plugs (Pitts et al 2015 J. Nucl. Mater. 463 748–75). Experiments have been undertaken at JET to assess the potential dependence of the radiated power asymmetry on plasma energy during SPI mitigated disruptions. Calculations of the toroidal asymmetry in the radiated power indicate that the toroidal peaking factor is largest near the SPI position and decreases with the plasma stored energy, which is a promising result in view of radiation heat loads during mitigated disruptions in ITER.

Reconstruction and interpretation of ionization asymmetry in magnetic confinement via synthetic diagnostics

Strong poloidal refueling asymmetry in the DIII-D tokamak is inferred from line radiation measurements. Synthetic diagnostics in neutral transport modeling coupled to gyrokinetic simulations illuminate implications for the plasma flow profile in the scrape-off layer of single-null beam-driven discharges. Recycling occurs primarily either on the inner or outer divertor legs, depending on the toroidal magnetic field direction. By reversing the toroidal magnetic field, the observed line radiation asymmetry is nearly eliminated or reversed. It is determined that, while relatively simple physics can describe the observed ionization asymmetry, predicting the overall brightness of the hydrogenic Lyman-α signal requires detailed simulation of the plasma and resulting turbulence. To this end, kinetic plasma simulations fully coupled to comprehensive neutral transport calculations—a novel capability—provide first-principles reproduction of Lyman-α observations on DIII-D.

Plasmoid drift and first wall heat deposition during ITER H-mode dual-SPIs in JOREK simulations

The heat flux mitigation during the thermal quench (TQ) by the shattered pellet injection (SPI) is one of the major elements of disruption mitigation strategy for ITER. It’s efficiency greatly depends on the SPI and the target plasma parameters, and is ultimately characterised by the heat deposition on to the plasma facing components. To investigate such heat deposition, JOREK simulations of neon-mixed dual-SPIs into ITER baseline H-mode and a ‘degraded H-mode’ with and without good injector synchronization are performed with focus on the first wall heat flux and its energy impact. It is found that low neon fraction SPIs into the baseline H-mode plasmas exhibit strong major radial plasmoid drift as the fragments arrive at the pedestal, accompanied by edge stochasticity. Significant density expulsion and outgoing heat flux occurs as a result, reducing the mitigation efficiency. Such drift motion could be mitigated by injecting higher neon fraction pellets, or by considering the pre-disruption confinement degradation, thus improving the radiation fraction. The radiation heat flux is found to peak in the vicinity of the fragment injection location in the early injection phase, while it relaxes later on due to parallel impurity transport. The overall radiation asymmetry could be significantly mitigated by good synchronization. Time integration of the local heat flux is carried out to provide its energy impact for wall heat damage assessment. For the baseline H-mode case with full pellet injection, melting of the stainless steel armour of the diagnostic port could occur near the injection port, which is acceptable, without any melting of the first wall tungsten tiles. For the degraded H-mode cases with quarter-pellet SPIs, which have 1/4 total volume of a full pellet, the maximum energy impact approaches the tolerable limit of the stainless steel with un-synchronized SPIs, and stays well below such limit for the perfectly synchronized ones.

Topological Nature of Radiation Asymmetry in Bilayer Metagratings.

Manipulating radiation asymmetry of photonic structures is of particular interest in many photonic applications such as directional optical antenna, high efficiency on-chip lasers, and coherent light control. Here, we proposed a term of pseudopolarization to reveal the topological nature of radiation asymmetry in bilayer metagratings. Robust pseudopolarization vortex with an integer topological charge exists in P-symmetry metagrating, allowing for tunable directionality ranging from -1 to 1 in synthetic parameter space. When P-symmetry breaking, such vortex becomes pairs of C points due to the conservation law of charge, leading to the phase difference of radiation asymmetry from π/2 to 3π/2. Furthermore, topologically enabled coherent perfect absorption is robust with customized phase difference at will between two counterpropagating external light sources. This Letter can not only enrich the understanding of two particular topological photonic behaviors, i.e., bound state in the continuum and unidirectional guided resonance, but also provide a topological view on radiation asymmetry, opening an unexplored avenue for asymmetric light manipulation in on-chip laser, light-light switch, and quantum emitters.

Impact of gas injection location and divertor surface material on ITER fusion power operation phase divertor performance assessed with SOLPS-ITER *

The ITER divertor design and performance assessment, primarily based on the SOLPS-4.3 burning plasma database (Pitts R. et al 2019 Nucl. Mater. Energy 20 100696), assumes the use of beryllium (Be) as the divertor surface material and the injection of gas from the main chamber top. However, the current ITER baseline favors gas injection from the more toroidally symmetric sub-divertor region. This paper evaluates the implications of these assumptions for divertor performance in the ITER fusion power operation phase. The impact of the divertor surface material and the gas injection location on the main ions mirrors the hydrogen only low power phase scenario shown in Park J.-S.et al (2020 Nucl. Fusion 61 016021). However, during burning plasma operation, extrinsic impurity seeding will be required. In the case of neon (Ne), studied here, impurity retention is influenced by both the divertor surface material and the fueling location. Neon leakage increases due to more energetic reflection from tungsten than beryllium, but equivalent divertor performance can be achieved by adjusting the neon seeding rate. While the impurity seeding location does not affect the distributions of impurity or radiation, the fueling location does. Top fueling provides local ionization sources mainly in the mid-SOL under detached conditions, enhancing divergences of the flux there (source-driven flow), bringing stagnation points close to the fueling location, and equilibrating flows towards both targets. In contrast, the global flow pattern (in the absence of fluid drifts) in the case of sub-divertor fueling is biased towards the inner target. Impurity flows, driven by force balance, largely mirror those of the main ion flow, including the stagnation point. The case with top fueling enhances Ne retention and corresponding radiation in the outer divertor, effectively reducing the total and peak target heat fluxes by 20%–40%, compared to the case with divertor fueling. Meanwhile, the case with outer target fueling also achieves similar reductions by enhancing plasma-neutral interactions. These results suggest the possibility that the selection of the fueling location and throughput can be used as an actuator to control impurity divertor retention and divertor radiation asymmetry.

Effect of 2/1 tearing mode on radiation asymmetry during disruptions on J-TEXT

Plasma disruption in the tokamak is a huge threat to the safe operation of ITER, which will cause serious damage to the tokamak device. At present, massive impurity injection is the main disruption mitigation method, include massive gas injection (MGI) and shattered pellet injection (SPI) which can dissipate most of the internal thermal energy via radiation. However, radiation asymmetry will still cause damage to the device when it results the concentration of radiation in a small area. It has been observed on many devices that n = 1 mode has a strong influence on radiation asymmetry. In this paper, the experimental results of radiation asymmetry on J-TEXT tokamak have been introduced, and there is a close to sine function relationship between toroidal peaking factor (TPF) and the phase of 2/1 tearing mode. It is found that when the injection position is aligned with the X-point of the pre-existing magnetic island, TPF has the maximum value, and while the injection position is between the X-point and the O-point, TPF has the minimum value. This will be helpful for the study of disruption mitigation of future large devices.

Experimental study on up-down asymmetry of tungsten impurities in EAST tokamak

By using the high-performance extreme ultraviolet spatial resolution impurity spectrometer, the up-down asymmetric distribution of tungsten impurity radiation in EAST tokamak is studied experimentally for the first time. The results show that during the co-directional neutral beam injection, the central toroidal rotation velocity is large, the up-down asymmetry is strong, and the side with strong radiation deviates from ion <inline-formula><tex-math id="Z-20240121170250">\begin{document}$B\times \nabla B$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20231448_Z-20240121170250.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20231448_Z-20240121170250.png"/></alternatives></inline-formula> drift direction. However, after injecting deuterated methane CD<sub>4</sub> into plasma through the valve of the upper divertor outer plate, the central toroidal rotation velocity decreases rapidly, and the asymmetry of the original tungsten impurity radiation decreases soon and finally reverses. In this work, a further statistical study of the W<sup>32+</sup> impurity radiation asymmetry factor <i>I</i><sub>u</sub>/<i>I</i><sub>d</sub> depending on the central toroidal rotation velocity <i>V</i><sub>t0</sub> is performed. The results show that when <i>V</i><sub>t0</sub> is larger than 30 km/s, the side with strong radiation deviates from ion <inline-formula><tex-math id="Z-20240121170255">\begin{document}$B\times \nabla B$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20231448_Z-20240121170255.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20231448_Z-20240121170255.png"/></alternatives></inline-formula> drift direction, however, when <i>V</i><sub>t0</sub> decreases to below 20 km/s, the asymmetry can be reversed. The relation of toroidal rotation velocity with impurity radiation asymmetry validates the prediction from drift-kinetic theory, and demonstrates that the centrifugal force induced by the toroidal rotation directly causes the asymmetric distribution of tungsten impurities through affecting the momentum conservation parallel to the magnetic field. The experimental observation of the asymmetric distribution of tungsten impurities in this work lays a solid foundation for further studying the poloidal transport of high-<i>Z</i> impurities and provides some important references for controlling the high-<i>Z</i> impurities in future fusion reactors.

On the use of error field correction coils in JET

This work describes the usage of Error Field Correction Coil (EFCC) system [Barlow I. et al. 2001 Fusion Eng. Des. 58–59 189], which is a set of 4 coils located external to the vessel of the JET device, with the aim of introducing non-axisymmetric n = 1 magnetic field perturbations in various targeted plasma experiments. Besides being used to characterize and correct the intrinsic error field, the EFCCs system has been exploited to i) probe plasma stability in high-βN regimes through the MHD spectroscopy technique, allowing the identification of resistive-wall mode stable operational scenarios, ii) study radiation asymmetry when testing the shattered pellet injector as the prime candidate for ITER disruption mitigation system, and iii) control edge localized modes, permitting a reduction in heat fluxes and carbon erosion of the divertor target plates.

Semi-hydro-equivalent design and performance extrapolation between 100 kJ-scale and NIF-scale indirect drive implosion

Extrapolation of implosion performance between different laser energy scales is investigated for indirect drive through a semi-hydro-equivalent design. Since radiation transport is non-hydro-equivalent, the peak radiation temperature of the hohlraum and the ablation velocity of the capsule ablator are not scale-invariant when the sizes of the hohlraum and the capsule are scale-varied. A semi-hydro-equivalent design method that keeps the implosion velocity Vi, adiabat αF, and PL/Rhc2 (where PL is the laser power and Rhc is the hohlraum and capsule scale length) scale-invariant, is proposed to create hydrodynamically similar implosions. The semi-hydro-equivalent design and the scaled implosion performance are investigated for the 100 kJ Laser Facility (100 kJ-scale) and the National Ignition Facility (NIF-scale) with about 2 MJ laser energy. It is found that the one-dimensional implosion performance is approximately hydro-equivalent when Vi and αF are kept the same. Owing to the non-hydro-equivalent radiation transport, the yield-over-clean without α-particle heating (YOCnoα) is slightly lower at 100 kJ-scale than at NIF-scale for the same scaled radiation asymmetry or the same initial perturbation of the hydrodynamic instability. The overall scaled two-dimensional implosion performance is slightly lower at 100 kJ-scale. The general Lawson criterion factor scales as χnoα2D∼S1.06±0.04 (where S is the scale-variation factor) for the semi-hydro-equivalent implosion design with a moderate YOCnoα. Our study indicates that χnoα ≈ 0.379 is the minimum requirement for the 100 kJ-scale implosion to demonstrate the ability to achieve marginal ignition at NIF-scale.

On the Possible Asymmetry in Gamma Rays from Andromeda Due to Inverse Compton Scattering of Star Light on Electrons from Dark Matter Annihilation

Dark matter is a popular candidate to a new source of primary-charged particles, especially positrons in cosmic rays, which are proposed to account for observable anomalies. While this hypothesis of decaying or annihilating DM is mostly applied for our Galaxy, it could possibly lead to some interesting phenomena when applied for the other ones. In this work, we look into the hypothetical asymmetry in gamma radiation from the upper and lower hemisphere of the dark matter halo of the Andromeda galaxy due to inverse Compton scattering of starlight on the DM-produced electrons and positrons. While our 2D toy model raises expectations for the possible effect, a more complex approach gives negligible effect for the dark halo case, but shows some prospects for a dark disk model.

Impact of solar radiation on indoor thermal comfort near highly glazed façades in a hot-humid subtropical climate: An experimental evaluation

Solar radiation has a profound impact on indoor thermal conditions, particularly in highly glazed spaces. However, there have been limited field measurements on this subject. Focusing on subtropical climate, this study investigated the effects of irradiation on thermal comfort from two aspects, disparities in glass properties and spatial positions, through a field measurement. Six test cells, each equipped with a representative type of glass, were established; two measurement points were set at inner and near-window positions to analyze the spatial disparities and impacts of solar radiation asymmetry. PMV-PPD-based evaluation criteria were employed to assess the long-term comfort levels and classified by environmental quality index (EQI); additionally, we assessed the risk of overheating by considering two indices: overheating hours and overheating severity, which represent the duration and extent of thermal discomfort. The results indicated that radiation asymmetry varied depending on glass properties and spatial/temporal difference, leading to partial thermal discomfort. Specifically, the MRT at the near-window point increased significantly, reaching 50.8 °C for single-pane glass, 40.1 °C for single-pane tinted glass, and a minimum of 32.8 °C for double-pane reflective glass after 14:30 due to direct sunlight. In contrast, the MRT at the indoor positions remained relatively stable at around 25 °C–27 °C, irrespective of the glazing type. SHGC of glass is critical for thermal comfort, as higher SHGC values intensify the sensation of extreme warmth. Through experiments, this study quantified the relationship between thermal discomfort and glazing properties, providing valuable insights for glazing facades design that can optimize indoor thermal environments.

Tangentially viewing hard X-ray imaging system and its measurement simulation on the HL-2M tokamak

A tangentially viewing Hard X-ray Real-Time Imaging (HXR-RTI) system and its measurement simulation on the HL-2M tokamak are presented. The HXR-RTI system mainly consists of a CsI:Tl scintillator crystal, a pinhole mechanism and a high-speed camera. When the CsI:Tl crystal is struck by the X-ray photons, certain wavelengths of visible or near-visible photons will be scintillated, which could be collected by the lens and imaged by the high-speed camera. This system can measure HXR with energy up to 300 keV, spatial resolution of less than 10 mm, and temporal resolution of several tens of microseconds. To understand the emission profile, we have developed a Geant4 model. The simulation results confirm that the spatial asymmetry will eventually lead to radiation asymmetry distribution. This system is designed for real-time exhibition of hard X-ray radiations from fast electron forward bremsstrahlung and will be used to study the dynamics of fast electrons.

Laser parameters affecting the asymmetric radiation of the electron in tightly focused intense laser pulses

The nonlinear radiation of the electron is a distinctive feature of the action of tightly focused linearly polarized lasers. In this paper, from the perspective of radiation symmetry, the effect of laser parameters on the electron radiation power in the time domain is studied systematically. An asymmetric bimodal structure is found in the time domain in the direction of the maximum radiation. For this special structure, an explanation is given based on the electron dynamics perspective. The structure is compared with the symmetric bimodal structure in the classical theory. The increase in laser intensity, while significantly increasing the radiated power of the electron, exacerbates the asymmetry of the electron radiation. The variation in the initial phase of the laser leads to a periodic variation in the electron motion, which results in a periodic extension of the electron spatial radiation with a period of π. Moreover, the existence of jump points with a phase difference of π in the range of 0–2π is found. The increase in pulse width reduces the radiated power, extends the radiation range, and alleviates the radiation asymmetry. The results in this paper contribute to the study of electron radiation characteristics in intense laser fields.

Continental drift shifts tropical rainfall by altering radiation and ocean heat transport.

Shifts in the position of the intertropical convergence zone (ITCZ) have great importance for weather, climate, and society. The ITCZ shifts have been extensively studied in current and future warmer climate; however, little is known for its migration in the past on geological time scales. Using an ensemble of climate simulations over the past 540 million years, we show that ITCZ migrations are controlled primarily by continental configuration through two competing pathways: hemispheric radiation asymmetry and cross-equatorial ocean heat transport. The hemispheric asymmetry of absorbed solar radiation is produced mainly by land-ocean albedo contrast, which can be predicted using only the landmass distribution. The cross-equatorial ocean heat transport is strongly associated with the hemispheric asymmetry of surface wind stress, which is, in turn, controlled by the hemispheric asymmetry of ocean surface area. These results allow the influence of continental evolution on global ocean-atmosphere circulations to be understood through simple mechanisms that depend primarily on the latitudinal distribution of land.

Comparison of different noble gas injections by massive gas injection on plasma disruption mitigation on Experimental Advanced Superconducting Tokamak

Massive gas injection (MGI) is a traditional plasma disruption mitigation method. This method directly injected massive gas into the pre-disruption plasma and had been developed on the Experimental Advanced Superconducting Tokamak (EAST). Different noble gas injection experiments, including He, Ne, and Ar, were performed to compare the mitigation effect of plasma disruption by evaluating the key parameters such as flight time, pre-thermal quench (pre-TQ), and current quench (CQ). The flight time was shorter for low atomic number (Z) gas, and the decrease in flight time by increasing the amount of gas was insignificant. However, both pre-TQ and CQ durations decreased considerably with the increase in gas injection amount. The effect of atomic mass on pre-TQ and CQ durations showed the opposite trend. The observed trend could help in controlling CQ duration in a reasonable area. Moreover, the analysis of radiation distribution with different impurity injections indicated that low Z impurity could reduce the asymmetry of radiation, which is valuable in mitigating plasma disruption. These results provided essential data support for plasma disruption mitigation on EAST and future fusion devices.

Assessing azimuthal asymmetry in the noise radiation from a three-core launch vehicle during liftoff

Creating accurate rocket noise models is important for assessing impacts on humans, the environment, and payloads. The United Launch Alliance Delta IV Heavy launch vehicle is unique because of the separation of the three cores and their associated RS-68A nozzles. This makes it a good candidate for determining how the asymmetry of nozzle configuration affects noise radiation, which can affect noise models. The NROL-82 and NROL-91 missions both launched from Vandenberg Spaceforce Base using Delta IV Heavy Vehicles. For both of these launches, acoustic data were recorded between ∼0.9 and ∼5.2 km from the vehicle at different azimuths to determine the extent of azimuthal asymmetry in noise radiation. Maximum overall sound pressure level, spectra, and overall power level were determined for each launch. Methods for comparing the datasets and results will be discussed.

Erratum to “The Asymmetry of the Cosmic Microwave Background Radiation as Signature of Local Lorentz Invariance Violation”

Erratum to “The Asymmetry of the Cosmic Microwave Background Radiation as Signature of Local Lorentz Invariance Violation”

Verification of compliance with the requirements of the norms for the internal microclimate of a corner room

The article considers the buildings of the transport infrastructure that provides services to transport workers, e.g. medical and preventive, children's educational and educative institutions. The resistance to heat transfer of the windows was not increased for such buildings at the last change in the norms of thermal protection in the Russian Federation in 2018. In this regard, it is important to check compliance with the requirements of regulatory documents for radiation temperature and asymmetry of the radiation temperature at the boundary of the serviced area of the premises of such buildings. A literary review has shown that much attention is paid to these parameters in the world. Since the heat transfer resistance of the windows is much less than that of the outer walls, the influence of the outside air temperature on the temperature of the inner surface of the window is much greater than that of the walls. The proposed article considers a corner room of an intermediate floor with windows in the outer walls, occupying 35% of the area of the external enclosing structures, in Belgorod. The building is serviced by air heating. A comparison of the radiation temperature and the asymmetry of the radiation temperature with the same indicators in the ordinary room considered earlier showed that with windows of the specified size, the influence of the second window significantly reduces the radiation temperature and increases the values of the local asymmetry of the radiation temperature. At the same time, during the estimated winter period, not only optimal, but also permissible requirements of the regulatory document are not met at the border of the serviced area of the premises.

ПРОВЕРКА ВЫПОЛНЕНИЯ ТРЕБОВАНИЙ НОРМ К ВНУТРЕННЕМУ МИКРОКЛИМАТУ УГЛОВОГО ПОМЕЩЕНИЯ

The article considers the buildings of medical and preventive, children's educational and educative institutions. The resistance to heat transfer of the windows is not increased for such buildings at the last change in the norms of thermal protection in the Russian Federation in 2018. In this regard, it is important to check compliance with the requirements of regulatory documents for radiation temperature and asymmetry of the radiation temperature at the boundary of the serviced area of the premises of such buildings. A literary review has shown that much attention is paid to these parameters in the world. Since the heat transfer resistance of the windows is much less than that of the outer walls, the influence of the outside air temperature on the temperature of the inner surface of the window is much greater than that of the walls. The proposed article considers a corner room of an intermediate floor with windows in the outer walls, occupying 35% of the area of the external enclosing structures in Belgorod. The building is serviced by air heating. A comparison of the radiation temperature and the asymmetry of the radiation temperature with the same indicators in the ordinary room considered earlier showed that with windows of the specified size, the influence of the second window significantly reduces the radiation temperature and increases the values of the local asymmetry of the radiation temperature. At the same time, during the estimated winter period optimal and permissible requirements of the regulatory document are not met at the border of the serviced area of the premises