Radiation Zone Research Articles

Electromagnetic Cascade Emission from Neutrino-coincident Tidal Disruption Events

The potential association between Tidal Disruption Events and high-energy astrophysical neutrinos implies the acceleration of cosmic rays. These accelerated particles will initiate electromagnetic (EM) cascades spanning from keV to GeV energies via the processes related to neutrino production. We model the EM cascade and neutrino emissions by numerically solving the time-dependent transport equations, and discuss the implications for AT2019dsg and AT2019fdr in the X-ray and γ-ray bands. We show that the γ-ray constraints from Fermi can constrain the size of the radiation zone and the maximum energy of injected protons, and that the corresponding expected neutrino event numbers in follow-up searches are limited to be less than about 0.1. Depending on the efficiency of p γ interactions and the time at which the target photons peak, the X-ray and γ-ray signals can be expected closer to the peak of the optical-ultraviolet luminosity or to the time of the neutrino production.

A multizone view on the multiwavelength emission of blazars

ABSTRACT In this work, a time-dependent modelling is developed to study the emission properties of blazars in the low state. Motivated by various observations, we speculate and assume that numerous discrete radiation zones throughout the jet of a blazar contribute to the broad-band emission. We model the temporal evolution of the electron spectrum in each emission zone taking into account the injection, cooling, and escape of relativistic electrons. By doing so, we are able to calculate the multiwavelength emission of each radiation zone. The observed emission of a blazar is then the superposition of the emission from all discrete radiation zones. We revisit the multiwavelength spectral energy distributions, light curves, and polarization under the model, and discuss its potential to reproduce the flat radio spectra, the core-shift phenomena, the minute-scale gamma-ray variability, and the large polarization-angle swings, which are difficult to explain under the conventional one-zone models simultaneously.

Observation of impurity accumulation and its compatibility with high plasma performance in W7-X

At the W7-X stellarator, the bolometer system has measured an intensive radiation zone in the inner plasma region (at a normalized radius ρ ∼ 0.3–0.4) in the hydrogen plasma generated by electron cyclotron resonance heating; it differs from the normal plasma radiation distribution with an edge-localized emission zone. Spectroscopic diagnostics have recorded high-Z elements such as iron. This phenomenon happens in the plasma phases after gas supply turn-off, which results in all impurity relevant diagnostic signals increasing for several seconds. Despite the enhancement of the core radiation, the plasma energy confinement is improved. A transport analysis shows that this impurity radiation behavior is associated with a low diffusion coefficient (D∼ 0.02 m2 s−1) and a reversal of the convection around the radial position of the emission peak, which, under normal conditions, separates the zones of outward convection in the central (|V| ∼ 0.1 m s−1) and inward convection in the outer region (|V| ∼ 0.3 m s−1). An impurity accumulation around this radial position has been identified. The transport coefficients obtained are comparable with the theoretical predictions of collisional impurity transport. In the plasma phases studied, both impurity and energy confinement are enhanced. The mechanism responsible for the improvement is believed to be a reduction of micro-instabilities associated with the observed steepening of the density profile, initiated by a low edge plasma density (<1.0 × 1019 m−3) after switching off the gas fueling. The normalized temperature and density gradients fulfil the condition for the suppression of ITG turbulence.

Integrating Commercial-Off-The-Shelf Components into Radiation-Hardened Drone Designs for Nuclear-Contaminated Search and Rescue Missions

This paper conducts a focused probabilistic risk assessment (PRA) on the reliability of commercial off-the-shelf (COTS) drones deployed for surveillance in areas with diverse radiation levels following a nuclear accident. The study employs the event tree/fault tree digraph approach, integrated with the dual-graph error propagation method (DEPM), to model sequences that could lead to loss of mission (LOM) scenarios due to combined hardware–software failures in the drone’s navigation system. The impact of radiation is simulated by a comparison of the total ionizing dose (TID) with the acceptable limit for each component. Errors are then propagated within the electronic hardware and software blocks to determine the navigation system’s reliability in different radiation zones. If the system is deemed unreliable, a strategy is suggested to identify the minimum radiation-hardening requirement for its subcomponents by reverse-engineering from the desired mission success criteria. The findings of this study can aid in the integration of COTS components into radiation-hardened (RAD-HARD) designs, optimizing the balance between cost, performance, and reliability in drone systems for nuclear-contaminated search and rescue missions.

Extraction, characterization and functionality assessment of Aloe vera, chitosan and silk sericin

Aloe vera, chitosan, and silk sericin have been investigated for their physicochemical properties as well as functional characteristics such as antibacterial, antioxidant, and UV resistance. Aloe vera was extracted by methanol as a solvent. Silk sericin was prepared from a boiled water solution of silk cocoons through ethanol precipitation, while chitosan was synthesized by deacetylation of chitin. FT-IR, TGA, DSC, EDX, UV–vis, and XRD were used to characterize the extracted Aloe vera, chitosan, and sericin. Antibacterial activity, antioxidant activity and UV protection factors were also investigated. The TGA graph revealed that the significant weight loss at 400 °C was 39%, 51%, and 52%. for Aloe vera, chitosan, and sericin, respectively. For E. coli, Aloe vera, chitosan, and silk sericin, the zones of inhibition were 2.5 mm, 3 mm, and 1 mm, respectively, whereas for S. aureus, the zones of inhibition were 4 mm, 5 mm, and 1.5 mm. The free radical scavenging activity of 10 mg/ml Aloe vera, chitosan and sericin was 93%, 53% and 52%, respectively. All three UV radiation zones were absorbed by an Aloe vera solution. Chitosan and silk sericin solution exclusively absorbed UV-C rays. These almost priceless natural resources can contribute to health-related beneficial issues.

Experimental characterization of TIAGO torch discharges: surface wave discharge behavior and (post-)discharge kinetics

The Torche à Injection Axial sur Guide d’Ondes source—better-known as the TIAGO torch—is a particular type of microwave-induced plasma that has become a focus of technological and scientific interest due to its outstanding features. Moreover, the TIAGO torch device arouses interest thanks to its remarkable performance in many challenging areas, such as green energy generation and graphene production by hydrocarbon decomposition. Although it has not been experimentally demonstrated to date, discharges generated by a TIAGO torch have been theoretically predicted to be surface wave discharges (SWDs), a kind of plasma leading the development of new materials. Therefore, deeper and fundamental research on this device is needed to optimize the implementation of plasma technology in these fields. In this study, the axial distribution of gas temperature, electron density and intensity of the main atomic and molecular emissions have been studied by optical emission spectroscopy when feeding the discharge with different input power values (200, 400 and 600 W). A complete axial characterization of both the dart and the plume regions is depicted and, according to the data obtained for the main plasma parameters, different regions can be identified, with the radiation zone being reported for the first time at atmospheric pressure. The kinetics of both the dart and the plume are discussed and an experimental verification of TIAGO torch behavior as a SWD is presented for the first time.

Electromagnetic radiation in chiral matter: The Cherenkov case

Starting from the modified Maxwell equations in Carroll-Field-Jackiw electrodynamics we study the electromagnetic radiation in a chiral medium characterized by an axion coupling $\theta(x)=b_\mu x^\mu$, with $b_\mu= (0,\mathbf{b})$, which gives rise to the magnetoelectric effect. Employing the stationary phase approximation we construct the Green's matrix in the radiation zone which allows the calculation of the corresponding electromagnetic potentials and fields for arbitrary sources. We obtain a general expression for the angular distribution of the radiated energy per unit frequency. As an application we consider a charge moving at constant velocity parallel to $\mathbf{b}$ in the medium and discuss the resulting Cherenkov radiation. We recover the vacuum Cherenkov radiation. For the case of a material with refraction index $n > 1$ we find that zero, one or two Cherenkov cones can appear. The spectral distribution of the radiation together with the comparison of the radiation output of each cone are presented, as well as some angular plots showing the appearance of the cones.

Тенденции развития лабораторий испытания и сертификации антенных комплексов в составе оборудования телекоммуникационных систем 5G NR

An analysis of international organizations involved in measuring the radiation characteristics of antenna systems in their near radiation zone is presented. Out of the great variety of such organizations we selected only those that specialize in testing of antenna system parameters for base stations and terminals that meet 5G NR telecommunication system standards. We have reviewed standards adopted by these testing laboratories and their cutting-edge samples of the testing systems. We have also analyzed the level of development of Russian specialized testing laboratories that perform testing and certification of 5G NR mobile network equipment. We have reviewed their equipment and capabilities for testing the parameters antenna systems being part of 5G NR telecommunication systems.

Argon–seeded detachment during ELM control by RMPs in KSTAR

In this study, we demonstrate argon-seeded discharges that exhibited a detached divertor during the full suppression and mitigation of edge-localized modes (ELMs) by an International Thermonuclear Experimental Reactor-like, three-row resonant magnetic perturbation (RMP) configuration in KSTAR. During the ELM suppression phase, the peak heat flux on the divertor target was successfully reduced from 1.6 MW m−2–0.5 MW m−2 via argon seeding. Further, the ion saturation current densities corresponding to the particle fluxes on both targets were reduced by more than 50%. During the RMP grassy-ELM regime, a further reduction to 0.1 MW m−2 in the divertor heat load was successfully achieved. A highly localized radiation zone near the X-point was also observed during divertor detachment. The calculated degree of detachment based on the two-point model increased to levels of approximately 3 and 2.3 for the outer target and inner target cases, respectively. These results provide valuable information regarding the effect of mid-Z impurities on RMP-detachment-compatible discharges.

Progress of Gamma Ray Irradiation Experiments on ITER Diagnostics from JADA

The Japan domestic agency (JADA) is responsible for procuring five diagnostic systems for ITER: the microfission chamber (MFC), poloidal polarimeter (PoPola), edge Thomson scattering (ETS), divertor impurity monitor (DIM), and divertor infrared thermography (IRTh) systems. Components of these systems that will be installed in high radiation zones must undergo radiation resistance tests to ensure reliability. The JADA diagnostic group has been conducting gamma ray irradiation experiments on diagnostic components at QST since 2018. The MFC is a neutron diagnostic system that uses uranium fission chambers, the mineral-insulated cables of which were evaluated for corrosion resistance. In-situ observations of the MFC preamplifier have been launched. The PoPola provides the plasma current profile by detecting the polarizations of far-infrared laser beams at their inlets and outlets. Irradiation tests confirmed the durability of PoPola piezo actuators. The ETS is a laser-aided diagnostic to measure electron temperature and density in plasmas from scattered spectra. Laser-induced damages to the optical elements caused by irradiation were investigated. The DIM is a spectroscopic system having a wavelength range of 200 nm to 1000 nm. The effects of irradiation on optical devices, metal mirrors, and radiation-resistant optical fibers were investigated. The IRTh is an infrared thermography system to observe the surface temperature of the divertor. The optical elements and electrical devices of the IRTh have undergone irradiation experiments. The progress of the gamma ray irradiation experiments on the ITER diagnostic systems from JADA are reported.

Anisotropic minimum dissipation subgrid-scale model in hybrid aeroacoustic simulations of human phonation.

This article deals with large-eddy simulations of three-dimensional incompressible laryngeal flow followed by acoustic simulations of human phonation of five cardinal English vowels, /ɑ, æ, i, o, u/. The flow and aeroacoustic simulations were performed in OpenFOAM and in-house code openCFS, respectively. Given the large variety of scales in the flow and acoustics, the simulation is separated into two steps: (1) computing the flow in the larynx using the finite volume method on a fine moving grid with 2.2 million elements, followed by (2) computing the sound sources separately and wave propagation to the radiation zone around the mouth using the finite element method on a coarse static grid with 33 000 elements. The numerical results showed that the anisotropic minimum dissipation model, which is not well known since it is not available in common CFD software, predicted stronger sound pressure levels at higher harmonics, and especially at first two formants, than the wall-adapting local eddy-viscosity model. The model on turbulent flow in the larynx was employed and a positive impact on the quality of simulated vowels was found.

Dynamics of shaded areas in a typical-shaped solar greenhouse and their effects on tomato growth—A case study in winter

The side walls and fixed insulation quilt of a solar greenhouse helped reduce heat loss from the room at night but produced shadows on the greenhouse floor during the day, affecting the growth and development of crops. In the present study, a method to calculate the projected area of the side walls and fixed insulation quilt in the greenhouse was derived. Then, a typical-shaped solar greenhouse and tomatoes were used as experimental research objects to investigate the spatial and temporal variation of indoor solar radiation intensity and tomato growth. The results showed that: 1) The average absolute error between the calculated and measured values of the ground shade of the solar greenhouse on four typical sunny days was 1.12%, 2.65%, and 2.02%, respectively. The area of selected greenhouse was 450m2, the maximum shaded area could account for 20.3% of the total area of the greenhouse, the shaded area projected by the insulation onto the greenhouse floor remained constant at different times, and that projected by the wall decreased and then increased parabolically with time. 2) The average solar radiation intensity in the greenhouse at the winter solstice tended to increase and then decrease with time, with a maximum value of 41,374.0 Lux. The uniformity of solar radiation distribution was reduced in the morning, evening and midday hours. 3) The tomato plant height, stem diameter, leaf area index and yield were 36.9%, 14.7%, 63.1% and 125.4% higher, respectively, in the high than in the low solar radiation zone. The results of the study can provide a theoretical basis for clarifying the dynamics of shaded areas and the spatial and temporal distribution of solar radiation intensity in greenhouses, and for optimizing the structural parameters of solar greenhouses.

Gravitational waves or x‐ray counterpart? No need to choose

AbstractBinary black holes emit gravitational waves (GWs) as they inspiral toward coalescence. Searches for electromagnetic counterparts to these GWs rely on looking for common sources producing both signals. In this article, we take a different approach: we investigate the impact of radiation zone effects, including retardation effects and gravitational wave propagation onto the circumbinary disk around stellar‐mass, spinning black holes, using general relativistic hydrodynamical simulations. Then we used a general relativistic ray‐tracing code to extract its x‐ray spectrum and lightcurve. This allowed us to show that radiation zone effects leave an imprint onto the disk, leading to quasi‐periodic patterns in the x‐ray lightcurve. The amplitude of the modulation is weak () but increases with time and is strongly dependent on the inclination angle.

Retarded potentials and radiation of a rotating charged rod

In this paper we determine the electromagnetic properties of a rotating charged rod, which rotates around the x-axis with an angular frequency that it’s not constant. As the charge is changing its position over time, the electromagnetic information reaches us with a certain time lag. Therefore, it is necessary to obtain the time-dependent(retarded) potentials at any point in space, for which we need multipolar expansion to determine the field at any point in space and do a Taylor expansion of the distance at which we want to measure the electromagnetic fields, in the static and induction zone. Then, we determine the Poynting vector in the corresponding radiation zone. Finally, we determine the radiated power, emphasizing the symmetries of the problem and showing how we can approach its solution considering these symmetries. .

Measurement and Model-Based Control of Solidification in Continuous Casting of Steel Billets

A laser vibrometer system in combination with appropriate artificial intelligence methods for clustering of the measured vibration spectra was tested at a continuous steel casting machine to receive information on the solidification status of the strand. Measurements with the laser vibrometer at a fixed strand position of the billet caster of ESF under conditions of incrementally increasing casting speeds revealed a transition in the population of the identified vibration clusters as a footprint of the passed crater end position with a change from a fully solidified strand to a strand with some liquid core at the measurement position. This was in accordance with the results from a three-dimensional dynamic temperature and solidification model which was set up based on a state-of-the-art approach for solution of the heat flow equation with tailored submodels for the different boundary zones of the ESF billet caster (i.e., mould, secondary spray water zones and radiation zones) and installed at the steel plant for online monitoring and control of the casting process. The application of the newly installed measurement and model-based information systems at ESF revealed significant improvements in their billet casting process in terms of halved strand breakout rates and correspondingly increased productivity.

PbO-TeO2-MgO-Na2O-B2O3 glasses: Optical properties and gamma ray shielding behaviour studies using the Monte Carlo simulation

Melt quenching is used to make the PbO-TeO2-MgO-Na2O-B2O3 glasses. As lead concentration rises, so does density rise from 3.283 to 3.923 g/cm3. The indirect band gap values decrease from 3.262 to 3.111 eV as lead oxide increases. The refractive index (n), optical dielectric constant, and dielectric constant (ε) increase from 2.329 to 2.368, 4.428 – 4.606, and 5.428 – 5.606 with the increase in lead content. The metallization value of all the samples is less than unity which confirms the non-metallic nature of all samples. The partial replacement of B2O3 by PbO compounds affects also the shielding characteristics. The Monte Carlo simulation for the gamma-ray shielding parameters depicts that the linear attenuation coefficient (LAC) of the fabricated samples increases gradually with rising the B2O3 substitution ratio. For example, at 244 keV, the linear attenuation coefficient enhances by 51% with increasing PbO content. The increase in LAC was associated with a significant decrease in the half-value thickness, thickness equivalent, and transmission factor while the radiation protection efficiency of the fabricated samples was enhanced. Therefore, fabricated glasses are considered a better choice to be used in the radiation zones.

Digital phased antenna array transceiver with multibeam radiation pattern

A transceiver has been designed for the digital generation of a multibeam radiation pattern in this work. The transceiver consists of a transmitter and receiver, both are integrated on a single printed circuit board. The transceiver provides the formation of multiple beams in the far field of the radiation zone. The experimental measurement of the multibeam radiation pattern of a phased antenna array with a digital pattern synthesis was carried out.

Evaluation of Environmental Radiation and Image Quality by Type of High-Energy Electromagnetic Wave Radiation Computed Tomography

With the enhancement of national income level, the number of computed tomography (CT) exams to diagnose diseases is increasing more and more. To utilize the data for the safety control of X-ray, the image quality of the environmental radiation at the boundaries in the radiation zone of the exam rooms by type of CT using highenergy electromagnetic wave. The locations of the environmental radiation measurement were shielding wall of the door for patients, door for patients, door to CT control room, shielding wall of the door for CT control room, and window to see the patients, and the glass dosimeters were installed 150 to 170 cm above the floor considering the location of the device to be measured for 3 months and analyzed. The environmental radiations in the MDCT room were measured with 3.09 ± 2.31 mSv, 0.51 ± 0.12 mSv, 0.99 ± 0.43 mSv, 0.27 ± 0.03 mSv, and 0.18 ± 0.03 mSv at the door to the control room, the wall of the control room, door for patients, door wall, and window to see the patients, respectively. In the mobile CT room, the radiation was detected only at the door of the control room with 1.65 ± 0.15 mSv, and no radiation was detected at the other boundaries. In the PET-CT room, the radiations were detected with 0.18 ± 0.03 mSv and 0.27 ± 0.03 mSv at the door and door wall, respectively, without detection at the other boundaries. Upon the results of image quality by CT devices, very satisfactory outcomes were found in terms of contrast, clarity of the boundaries, and detection rate of lesions in all the acquired images, and also very satisfactory in the functional evaluations of the organs in PET-CT only. These results are anticipated to be used as the reference data to establish the systemic and efficient systems and policies in the safety control of X-ray in the future.

Radiation-reaction and angular momentum loss at the second post-Minkowskian order

We compute the variation of the Fokker-Wheeler-Feynman total linear and angular momentum of a gravitationally interacting binary system under the second post-Minkowskian retarded dynamics. The resulting $O({G}^{2})$ equations-of-motion-based, total change in the system's angular momentum is found to agree with existing computations that assumed balance with angular momentum fluxes in the radiation zone.

Impact of a binary black hole on its outer circumbinary disc

ABSTRACTAccreting supermassive binary black holes (SMBBHs) are potential targets for multimessenger astronomy as they emit gravitational waves (GW) while their environment emits electromagnetic (EM) waves. In order to get the most out of a joint GW–EM detection we first need to obtain theoretically predicted EM signals unambiguously linked to BBHs. In that respect, this is the first of a series of papers dedicated to accreting pre-merger BBHs and their associated EM observables. Here, we extend our Numerical Observatory of Violent Accreting systems, e-NOVAs, to any space–time. Unlike previous studies, almost exclusively focused on the inner regions, we investigated the impact of the BBH on its outer circumbinary disc, located in the radiation (or wave) zone, after implementing an approximate analytical space–time of spinning, inspiralling BBHs in e-NOVAs. We follow the formation of a weak spiral structure in disc density arising from the retardation effects in the radiation zone metric. Simulation data are then post-processed with a general-relativistic ray-tracing code incorporating the same BBH space–time, assuming SMBBH sources. The density spiral creates a small $({\lt }1{{\ \rm per\ cent}})$ but unambiguous modulation of the light curve at the semi-orbital period. This signal, although weak, is fundamentally different from that of an axisymmetric disc around a single BH providing a lower limit on the impact of a BBH on its outer disc. This potential difference being found, we study how binary parameters impact this modulation in order to find the optimal case which is a high source inclination of any binary mass ratio (from 0.1 to 1).