Search

This paper established a three-dimensional transient MHD model of a high-current multi-component vacuum arc under a transverse magnetic field (TMF) to simulate the dynamic characteristics of plasma parameters in the uniform motion mode of a contracted arc under lower TMF. The model considered the ionization–recombination process among the multi-components and used the P1 model to calculate the thermal radiation losses. The simulation results show that the ion number density of The TMF arc is on the order 1024 m−3, and when the plasma temperature reaches 4.3 eV, the effects of thermal radiation cannot be ignored. The majority of the plasma from the cathode and anode undergo acceleration and then deceleration before finally intersecting at the center of the arc, creating an extreme value of the density and the pressure, where a large amount of kinetic energy is converted into internal energy. The arc will be bent and deflected under the action of the ampere force, and the deflection of Cu3+ is especially obvious. The TMF affects the collision strength of the jet in the intersection area and, thus, affects the ion density, in which the change of Cu2+ is dominant. The ionization–recombination process of ions is mainly determined by the electron temperature, which is affected by the arc current. As the current decreases, Cu1+ increases and Cu2+ and Cu3+ decrease, and the change in ionization rate is the main reason for the change in the proportion of each ionic component; the heat flux density to the anode and cathode is on the order of 1010 W/m2, which heats the front of the arc and ensures the stable movement of the arc. Meanwhile, due to the high ion number density, the ion heat flux accounts for the main part of the heat flux, and the anode exhibits a higher proportion of ion heat flux. [ABSTRACT FROM AUTHOR]

A nanosecond Nd:YAG laser was used to study the laser ablation of aluminum foil in the phase explosion regime at a laser intensity range of 0.63–3.61 × 10 12 W / cm 2. Laser ablation and plasma characteristics were studied using microscopic ablation crater images, plasma emission spectra, and plasma plume images. Measured plasma density using a Stark width of Al I (396.2 nm) showed a strong linear correlation with crater size, with a Pearson correlation coefficient (r) of 0.97. To understand the origin of this linear correlation, plasma temperature was estimated using Bremsstrahlung emission from 512 to 700 nm. The estimated plasma temperature and aspect ratio of the plasma plume were negatively correlated, having r = − 0.76. This negative correlation resulted from a laser-plasma interaction, which heated the plasma and increased its hydrodynamic length. The percentages of laser energy used for plasma heating ( E p / E L ) and Al foil ablation ( E Al / E L ) were estimated from plasma temperature. Increased E Al / E L , such as crater size, with increasing laser intensity, confirms that greater mass ablation is the fundamental reason for the strong linear correlation between crater size and plasma density. [ABSTRACT FROM AUTHOR]

The long-term storage performance of energetic multilayer nanofilms is of great significance for their applications. In this paper, it is proposed to add a 10 nm Cu barrier layer between Al/CuO composite films to increase their storage stability. The Al/CuO composite film and Al/Cu/CuO composite film were aged for 14 days in an environment with a relative humidity of 40% and a temperature of 71 °C. Scanning electron microscopy and differential scanning calorimetry were used to analyze the microstructure and thermodynamic properties of the energetic films before and after aging, and the electrical detonation performance and ignition ability of energy-containing semiconductor bridges were studied. The results indicate that after aging for 14 days in an environment with a relative humidity of 40% and a temperature of 71 °C, the Al layer of the Al/CuO composite film becomes thinner, the Al2O3 interface layer increases, and the heat release decreases. The interlayer microstructure of the Al/Cu/CuO energetic multilayer nanofilms did not change significantly, and the addition of a 10 nm Cu layer formed a low-temperature Al–Cu alloy, reducing the reaction initiation temperature from 626 to 570 °C. The critical ignition time and critical ignition energy of the Al/CuO-energetic semiconductor bridge (ESCB) increased, the flame duration shortened from 440 to 300 μs, the flame size decreased by 50%, the plasma temperature decreased, and aging had no significant effect on the electrical explosion performance of Al/Cu/CuO-ESCB. After aging for 14 days in an environment with a relative humidity of 40% and a temperature of 71 °C, the maximum ignition gap of B/KNO3 for Al/CuO-ESCB decreased from 1.4 to 1.2 mm, while the maximum ignition gap for Al/Cu/CuO-ESCB remained at 1.6 mm, which significantly improved the ignition performance and long storage performance of the energetic semiconductor bridge. [ABSTRACT FROM AUTHOR]

Understanding the behavior of intrinsic defects and helium (He) in tungsten oxides is useful for the application of tungsten (W) in a fusion environment because of the oxidation of W surfaces. The formation and diffusion energies of intrinsic defects and He in monoclinic γ-WO3 have been investigated using first-principles density functional theory calculations. The formation energy and diffusion activation energy of O defects are lower than W defects. O vacancy prefers to diffuse along the ⟨ 001 ⟩ direction, then followed by ⟨ 010 ⟩ and ⟨ 100 ⟩ directions; however, the W vacancy is immobile at temperatures lower than 2000 K. The stability of Schottky defects (SDs) is sensitive to their geometry and orientation. W interstitials prefer to move along the [100] direction, while O interstitials jump around W atoms rather than through the W quasi-cubic centers. He interstitial atoms are predicted to have a high solubility and an anisotropic diffusion mechanism in γ-WO3. In addition, the effect of biaxial strain on the solubility and diffusivity of He interstitials was investigated. He interstitials prefer to reside at individual sites rather than clusters. He atoms are weakly trapped by single vacancies or SDs. Vacancies assist the local migration of nearby He. Correspondingly, He self-clustering and bubble formation are less likely to form in γ-WO3 relative to bcc W. The energetics obtained in this work can be used to predict the microstructure evolution of the WO3 layer on a W substrate exposed to He plasmas at different temperatures. [ABSTRACT FROM AUTHOR]

Spherical powders are required for many advanced manufacturing techniques due to their inherent requirement of flowability, either within feed tubes or during powder spreading. As advanced manufacturing of magnets continues to develop, new production methods for feedstocks are also sought. Plasma spheroidization is a high-yield method to produce spherical Nd–Fe–B powders from irregularly shaped particles, with advantages including high throughput and a well-controlled size distribution. Highly spherical Nd–Fe–B powders with large scale production (i.e., kg) have been demonstrated using an inductively coupled thermal plasma system; however, the magnetic properties of the output powder display significant degradation. The coercivity was decreased from the initial 8 kOe (636 kA/m) of the as-received to 0.7 kOe (55 kA/m) for spheroidized powders. Microstructural investigation reveals 6% Nd depletion caused by the extreme temperatures of the plasma, leading to the formation of low-coercivity α-Fe and a subsequent decrease in energy product. Post-spheroidization heat treatments with Nd can partially mitigate the coercivity degradation, increasing to 1.7 kOe (135 kA/m), potentially offering a pathway toward spherical powders for a range of applications. [ABSTRACT FROM AUTHOR]

The described method is intended for application as a diagnostic tool for a nonstationary, short-lived plasma (in particular, for the laser-produced plasma). It is based on taking into account the lifetime of a laser-produced plasma, which is so short (several nanoseconds) that it is not enough for the ionization equilibrium to be established. Among mechanisms leading to appearance of an ion with a given charge Z in the plasma, only the electron-collisional ionization is considered, because contributions of other phenomena turn out to be negligible. The method is discussed as an example of a plasma excited on the Xe gas-jet target. The necessary collisional cross sections of ions from+7Xe to+16Xe have been calculated specifically for this study using a quantum-mechanical numerical simulation, with its principles and features being also presented in the paper. To demonstrate capabilities of the method, it has been applied to one of the experimental cases when the plasma was produced by the laser beam focused on the Xe gas-jet target. The time-integrated energy of laser radiation absorbed in the plasma was measured, and the absorption coefficient, μ, was derived from it with a correction for the plasma lifetime, which was several times shorter than the laser pulse. Using the method described here, the values of ⟨ Z ⟩ and then μ were calculated as a function of temperature. The time-averaged plasma temperature, T, in the above-mentioned experiment was believed to be equal to that at which the calculated and experimentally determined values of μ coincided. The following results were obtained: T = 42 eV, ⟨ Z ⟩ = 10.2. [ABSTRACT FROM AUTHOR]

This study explores the effects of chamber pressure on the electrical and thermodynamic characteristics of a low-pressure thermal plasma jet. The investigation focuses on current–voltage characteristics, arc voltage fluctuations, plasma jet temperature, electron density, and velocity within the range of 100–500 A arc current, at chamber pressures of 100 Pa, 1 kPa, and 3 kPa. Spectral analysis of the arc voltage reveals the presence of distinct frequencies, including restrike, Helmholtz, and acoustic modes, which exhibit varying behavior under different chamber pressure conditions. Restrike frequency shows an increase with decreasing chamber pressure, while Helmholtz frequency remains unaffected, and the power density of the acoustic frequency diminishes, eventually disappearing from the spectrum. The transition of the plasma jet from a continuum regime to a frozen state with decreasing chamber pressure is observed along with its shock structures. Optical emission spectroscopy is utilized to map the excitation temperature and electron density profile along the jet axis, demonstrating that the jet temperature and density peaks at the compression zone. Furthermore, Mach probe measurements of the plasma jet velocity at different axial locations, under various chamber pressure conditions, illustrate that the plasma jet maintains a supersonic state, regardless of chamber pressure. However, after the formation of a Mach disk, the jet velocity becomes subsonic. The highest velocity is achieved at 100 Pa chamber pressure, reaching Mach 2.9 at 50 mm from the anode exit. This research enhances our understanding of thermal plasma jets under low-pressure conditions, contributing to the advancement of knowledge in their applications across various domains. [ABSTRACT FROM AUTHOR]

It is imperative to develop the simulation of vacuum arcs as a tool to aid electrode design in vacuum circuit breakers. Although the development of electromagnetic thermo‐fluid simulations for vacuum arcs has been reported, most of them do not take cathode sheath phenomena into account and have not been able to reproduce vacuum arc phenomena, especially cathode spots. As the first step, the cathode sheath voltage, cathode surface electric field, and temperature and field (T‐F) electron emission current were analyzed numerically on the basis of the space charge in the cathode sheath. In this study, the cathode sheath was assumed to exist when the charge density induced on the cathode surface is positive, and the temperature and density of vacuum arc plasma and cathode temperature, which are physical quantities obtained by electromagnetic thermo‐fluid simulation, were used as parameters of the analysis. As a result, the cathode sheath voltage, electric field, and electron emission current density can be calculated from the vacuum arc plasma temperature, density, and cathode temperature. Numerical results show that the electron emission current density has a dominant effect on the presence or absence of the cathode sheath. [ABSTRACT FROM AUTHOR]

In this research, animal samples were subjected to skin rejuvenation using the floating electrode dielectric barrier discharge plasma device. Plasma processing was performed on the dorsal area of the rat's neck, covering a surface area of 18 cm2. Biometric assessments, encompassing measurements of skin surface evaporation, moisture content, melanin and erythema levels, as well as skin firmness and elasticity, were conducted before treatment initiation, immediately posttreatment, at the 4th and the 10th week during the follow‐up period. Physical examinations were employed to investigate and record the active species generated by plasma as well as the temperature of the skin surface. The skin ultrasound device was utilized to assess the density and thickness of both the epidermis and dermis. [ABSTRACT FROM AUTHOR]

A new portable miniaturized atmospheric microplasma discharge (μAPD) system coupled with the optical emission spectrometry (OES) detection for the determination of Hg in water samples was developed. The device was built from cheap, easily replaceable, and commercially available parts and was able to work with the photo-induced chemical vapor generation (PCVG). To optimize the photochemical volatile Hg generation process, a wide range of low molecular weight organic compounds (LMWOCs), namely formic, oxalic, acetic, propionic, and malonic acids, in addition to methanol, ethanol, glycerin, ethylene glycol, formaldehyde, and acetaldehyde, were tested to establish their influence on the signal of Hg. To assess the excitation and atomization potential of the newly developed μAPD system and its impact on the analytical performance of this microplasma excitation source, the plasma temperatures and the electron number density were evaluated. The analytical figures of merit were determined for the coupled PCVG-μAPD system. Additionally, the usability of the method was tested in reference to the analysis of selected environmental samples, i.e., tap, well, and river water spiked with Hg. A recovery test was also performed to evaluate the accuracy of the method. The examined analytical system allowed to detect Hg in water at a level lower than 0.33 μg L−1 when operating it at relatively low sample flow rates (2 mL min−1) and Ar supporting and plasma forming gas rates (20 mL min−1). The precision of measurements was better than 5% for formic acid. We believe that the presented system might be an attractive, cheaper alternative to commercial, highly expensive systems, e.g. based on inductively coupled plasma optical emission spectrometry (ICP OES). [ABSTRACT FROM AUTHOR]

The mechanism of double-pulse laser irradiation under spatial confinement remains unclear due to complex plasma plume dynamics and multiple shock wave interactions. In this study, coupling of spatial confinement and double-pulse irradiation was investigated using fast photography, laser shadowgraphy, and spectroscopy. The experimental results demonstrated unique dynamic processes of plasma plume and shock waves, confirming that the plasma plume was eventually reshaped into a jet-like structure, and the combined enhancement effect can be regulated through different parameters, including inter-pulse delay and plate spacing. The inter-pulse delay dictates the primary mechanism of the secondary pulse's interaction with the initial plasma and the target surface; as it increases, plasma front absorption decreases while target surface ablation intensifies. Plate spacing determines the delay from laser incidence to plasma plume compression; along with the inter-pulse delay, it influences whether the secondary pulse generates a second-generation shock wave that merges with the initial shock wave for compression or performs a secondary compression after the first. Compared to double-pulse irradiation alone, combined enhancement increased emission intensity of Fe, Ni, and C spectra by up to 4.1 times accompanied by the increase in plasma temperature. The R2 of calibration curves was increased, and the sensitivity for trace components Cr and C was improved with limits of detection reaching 255 and 659 ppm. [ABSTRACT FROM AUTHOR]

This paper is devoted to the experimental study of the characteristics of a continuous optical discharge (COD) sustained by high power continuous wave laser radiation at a wavelength λ = 1.08 μ m in high pressure argon. New data on the COD threshold laser power dependence of argon pressure in the range 20–50 bar is obtained. The COD threshold laser power is shown to be in good agreement with the data obtained by other authors and theoretical evaluations provided the contribution of plasma energy loss due to thermal radiation is taken into account properly. The maximum plasma temperature was estimated to be 20–21 kk or higher, favorable to obtain high UV spectral radiance. A study of the convective plume oscillations around COD in argon has been carried out. It is found that in the pressure range 25–35 bars the growth of the laser radiation power leads to a decrease in convection oscillation frequency from 33 to 29 Hz, while the radius of the convective plume grows accordingly. The oscillation frequency ν and characteristic radius of the convective plume r 0 were found to obey the similarity relation ν = 0.5 g / 2 r 0 previously established in experiments with COD in xenon. These results are promising for using COD in argon as a high brightness broadband UV radiation source. [ABSTRACT FROM AUTHOR]

Hydrogen, as a kind of green and efficient energy, plays an increasingly important role in current social development. Hydrogen storage technology is considered to be one of the main bottlenecks in limiting the large-scale application of hydrogen energy. The solid-state hydrogen storage technology based on Mg-based materials has received extensive attention due to its advantages of high hydrogen capacity, good reversibility, and low cost, but there are still shortcomings such as high reaction temperature, large energy consumption, and slow reaction kinetics. In order to solve these problems, this article proposes a new method of using microwave plasma to ionize hydrogen into H− ion. The possible activation mechanism of microwave plasma to improve the hydrogen storage properties is put forward. Based on the activation mechanism, the thermodynamic performance of Mg-based hydrogen storage is evaluated using density functional theory. It is concluded that the reaction temperature is significantly reduced from 339°C to 109°C with the help of microwave plasma. In addition, the comparison between the conventional heating hydrogen storage process based on MgH2 and microwave enhanced advanced hydrogen storage process based on MgH2 systems coupled with solid oxide fuel cells for heat and power generation is conducted to evaluate the economic feasibility. The results show that the energy consumption cost of the proposed microwave plasma enhancing hydrogen storage system is approximately 1.71 $/kgH2, which is about 50% of the energy consumption cost of the conventional system. [ABSTRACT FROM AUTHOR]

ABSTRACT This research examines the correlation between temperature effects and surface charging problems on a silicon dioxide mask using simulation techniques. The findings of this study validate the significance of considering electron–solid interactions, especially when influenced by varying temperatures. The impacts of temperature changes on the spatial distributions of net charge deposition, electric potential, and electric field are examined. It was noted that the temperature rise leads to an increase in the concentration of positively charged holes near the surface of the mask, thereby diminishing the spatial dispersion of positive potential. This results in a less conspicuous alteration of the mask profile as the temperature increases. This investigation is anticipated to possess substantial significance and offer valuable insights for optimizing mask design. [ABSTRACT FROM AUTHOR]

The impact of plasma temperature on the formation and evolution of distinct and unique molecular species recorded as molecular signatures from laser induced plasma (LIP) was examined in this study. A definitive correlation between plasma temperature and the formation of molecular species has been established through a comprehensive temporal analysis of BO and BO2 molecular bands. The utilization of the signal-to-envelope ratio diagrams allowed for pinpointing the optimal temperature range for molecule emission. Notably, the molecule BO exhibited an ideal temperature range of 10,000–11,000 K for the proper formation of molecular emission bands, while BO2 preferred temperatures between 8,000–9,000 K. These optimal temperature ranges remained consistent regardless of the laser irradiation wavelength or ambient gas conditions of Ar, air or He studied in this work. These key findings highlight the significant influence of plasma temperature in shaping the molecular species observed in LIP. [ABSTRACT FROM AUTHOR]

Prealloyed powders present a promising alternative to traditional ball milling processes in powder metallurgy, addressing challenges such as uneven powder mixing and incomplete reinforcement reactions. This study investigates the preparation of Ti–TiBw composites using spark plasma sintering (SPS) at temperatures ranging from 950 to 1050 °C, utilizing Ti–TiBw prealloyed composite powders. The effects of sintering temperature on the microstructure and mechanical properties of Ti–TiBw composites are studied, comparing prealloyed composite powders with ball‐milled premixed powders. As a result, the composites exhibit excellent strength and ductility, with an ultimate tensile strength of 676 MPa at 1000 °C and an elongation of 20.42% at 1050 °C. Comparatively, Ti–TiBw composites prepared from premixed powders achieve densification at 1050 °C, 50 °C higher than those prepared from prealloyed powders. [ABSTRACT FROM AUTHOR]

The theory of ion-acoustic solitons in nonrelativistic fully degenerate plasmas and nonrelativistic and ultra-relativistic degenerate plasmas at low temperatures is known. We consider a multi-component relativistic degenerate electron-positron-ion plasma at finite temperatures. Specifically, we focus on the intermediate region where the particle's thermal energy (k B T) and the rest mass energy (m c 2) do not differ significantly, i.e., k B T ∼ m c 2 . However, the Fermi energy (k B T F) is larger than the thermal energy and the normalized chemical energy ( ξ = μ / k B T ) is positive and finite. Two different parameter regimes with β ≡ k B T / m c 2 < 1 and β > 1 , relevant for astrophysical plasmas, are defined, and the existence of small amplitude ion-acoustic solitons in these regimes are studied, including the critical cases where the known KdV (Korteweg–de Vries) theory fails. We show that while the solitons with both the positive (compressive) and negative (rarefactive) potentials coexist in the case of β < 1 , only compressive solitons can exist in the other regime (β > 1) . Furthermore, while the rarefactive solitons within the parameter domains of β and ξ can evolve with increasing amplitude and hence increasing energy, the energy of compressive solitons reaches a steady state. [ABSTRACT FROM AUTHOR]

Hot electrons generated by the two-plasmon-decay (TPD) instability in laser-direct-drive implosions preheat the fuel and degrade performance. The mitigation of preheat using silicon-doped ablators (i.e., preheat is reduced by a factor of 1.40 ± 0.04) while decreasing the ratio of the laser spot diameter to the target diameter ( R b / R t ) to mitigate cross-beam energy transfer has been demonstrated on the OMEGA laser for quarter-critical laser intensities of 4.1 × 10 14 W / c m 2 , equivalent to an incident laser intensity of 8.3 × 10 14 W / c m 2 . The silicon dopant increases the electron temperature of the ablation plasma, which raises the intensity threshold for the onset of the TPD instability. These results show that implosion designs utilizing higher drive intensities can be used to achieve higher shell velocities, which are currently inaccessible with plastic ablators due to excessive preheat. [ABSTRACT FROM AUTHOR]

Herein, a selective passivation of p‐GaN via hydrogen plasma treatment for InGaN single‐quantum‐well (SQW) red light‐emitting diodes (LEDs) is reported. Insulating regions are formed on the p‐GaN top surface via hydrogen plasma treatment, suppressing current injection beneath the p‐pad and along the mesa perimeter to increase light output and mitigate non‐radiative recombination. The fabricated LEDs demonstrate a high on‐wafer light output power density of >88 mW cm−2, a peak on‐wafer external quantum efficiency of 0.65%, and on‐wafer wall‐plug efficiency of 0.41% with a 645 nm peak emission wavelength at 10 mA (7.2 A cm−2) current injection. Further, the temperature dependence of InGaN SQW red LEDs is compared with their AlGaInP counterparts. InGaN SQW red LEDs exhibit a high characteristic temperature of 208 K and a small redshift coefficient of 0.072 nm K−1 at 72 A cm−2 current injection, which are almost 3 and 2 times better than the characteristics of AlGaInP red LEDs, respectively. [ABSTRACT FROM AUTHOR]

A model for fast electron-driven high-density plasma is proposed to describe the effect of injected fast electrons on the temperature and inner pressure of the plasma in the fast heating process of the double-cone ignition (DCI) scheme. Due to the collision of the two low-density plasmas, the density and volume of the high-density plasma vary. Therefore, the ignition temperature and energy requirement of the high-density plasma vary at different moments, and the required energy for hot electrons to heat the plasma also changes. In practical experiments, the energy input of hot electrons needs to be considered. To reduce the energy input of hot electrons, the optimal moment and the shortest time for injecting hot electrons with minimum energy are analyzed. In this paper, it is proposed to inject hot electrons for a short time to heat the high-density plasma to a relatively high temperature. Then, the alpha particles with the high heating rate and P d V work heat the plasma to the ignition temperature, further reducing the energy required to inject hot electrons. The study of the injection time of fast electrons can reduce the energy requirement of fast electrons for the high-density plasma and increase the probability of successful ignition of the high-density plasma. [ABSTRACT FROM AUTHOR]

An understanding of the behaviour of the D or He fuel used in tokamak discharges is essential in analyses such as modelling edge and divertor transport and the erosion of the vessel walls. However, poor agreement is found between measurements made on the JET tokamak and collisional-radiative models used to predict the hydrogen-like D and He line intensities. The range of temperatures of the plasmas emitting the radiation is also limited, in contrast to that for many impurities for which a wide range is possible. This is particularly so for He II whose line intensities tend to have the same near-constant ratios in most pulses, suggesting that the emission originates in plasma regions with very similar electron temperatures. To gain understanding and to allow quantitative comparisons with theoretical models, extensive observations of the VUV Lyman series have been made, for all discharge scenarios run during three He campaigns. Those for He discharges in both JET ITER-like wall (JET-ILW) and JET C (JET-C) campaigns are presented here. He discharges have the advantage of fewer impurities resulting in less complex spectra than when D is used as the fuel. However, the characteristics of the observed discrepancies are similar in both species, allowing He to be used as a proxy for D in order to gain understanding of the discrepancy. In addition, the study of He avoids the complication of molecular species contributing to the level populations. Opacity effects are also expected to be less severe in He discharges. Nevertheless, so as to ensure that the measurements are not unduly affected by opacity, comparisons have also been made with emission from Balmer and Paschen series members. Measurements of both line intensities and their ratios are presented for all-pulse surveys and for individual pulses. In exceptional cases in which the He emission is intense a dependence on the He II line intensity is demonstrated. The discrepancy between these measurements and the theoretical models is illustrated. [ABSTRACT FROM AUTHOR]

To explore the asymmetry in ion and electron heating at Earth's magnetotail at mid‐tail distances (XGSM< ${X}_{\mathit{GSM}}< $ −30 RE ${R}_{E}$), we analyze near‐simultaneous observations of reconnection outflows from two opposite sides of reconnection sites at those distances using Magnetospheric Multiscale (MMS) and Acceleration, Reconnection, Turbulence and Electrodynamics of Moon's Interaction with the Sun (ARTEMIS) data. We report a pronounced temperature asymmetry between the earthward and tailward reconnection outflows. The asymmetry is more significant for electrons than for ions: Earthward moving ions are only three times hotter than tailward ones, but earthward moving electrons are 5–20 times hotter than tailward ones. The closed field‐line topology on the earthward side of the reconnection region, as opposed to the open topology on the tailward side, is likely a critical contributor to this asymmetry. These findings cast light on the underlying mechanisms of particle heating and energization in magnetotail reconnection, highlighting the significant role of Earth's dipolar magnetic field. This study offers insights for refining magnetic reconnection models, emphasizing the importance of incorporating realistic magnetic field topologies to accurately simulate the heating and energization processes observed in space plasma environments. Key Points: Ions and electrons exhibit higher temperatures earthward of mid‐tail reconnection than tailwardIons are three times hotter earthward than tailward and electrons are 5–20 times hotter earthward than tailwardWe suggest that the temperature asymmetry is due to the closed magnetic field earthward and open field tailward of the reconnection site [ABSTRACT FROM AUTHOR]

A possibility of studying effects of the main background ions formed by the main elements of inductively coupled plasma (H, N, O, and Ar) at the working parameters of the normal ("hot") plasma mode by thermodynamic modeling is assessed. Such ions, responsible for the strongest spectral interferences in the mass spectra are always observed upon the injection of aqueous ("wet") sample solutions into inductively coupled plasma mass spectrometers (ICP MS). The quantitative composition of the main background ions in an ICP MS is calculated as a function of plasma temperature in the temperature range from 3000 to 8000 K using thermodynamic modeling. The results of modeling were compared with the experimental data on the measured mass spectra of the main background ions and a high degree of correlation between the theoretical and experimental results was shown. The agreement between the results of calculations the experimental data validates the thermodynamic model of thermochemical processes in an ICP MS used and its applicability to subsequent calculations in fulfilling analytical tasks. A possibility of the unambiguous assessment of gas-kinetic plasma temperature is confirmed by comparing the theoretical and experimental mass spectra of the main ICP background ions in a normal mode. It was found that the calculated and experimental data on the concentration of only NO+ ions do not agree with the regularities noticed for the other background ions in the normal ICP mode. [ABSTRACT FROM AUTHOR]

The Extreme ultraviolet Variability Experiment (EVE) is one of three instruments onboard the Solar Dynamics Observatory (SDO). This paper focuses on using the "A" channel on the Multiple EUV Grating Spectrographs (MEGS-A) on EVE, which measures wavelengths of 5 – 37 nm, to improve the wavelength scale accuracy and spectral resolution during solar flares. EVE's least processed (Level 0B) data product is used to create updated wavelength scales that are shown, through this analysis, to make more precise spectral measurements compared to EVE Level 2 data. An X2.2 class flare that occurred on 15 February 2011, SOL2011-02-15T0156, was used to derive the pixel-to-wavelength scales. An improvement range of 5.21% to 11.35% was found in the emission line widths. In the future, these measurements can be used for improved Doppler velocity calculations of the accelerated plasma of various temperatures during solar flares. [ABSTRACT FROM AUTHOR]

Laser-induced breakdown spectroscopy (LIBS), a rapid and nondestructive elemental analysis method, is widely applied across various fields. This technique is used for elemental analysis of materials by analyzing the light emitted from laser-induced plasma, with plasma temperature being a crucial parameter. This study focused on obtaining time-resolved spectra of Cu samples at different distances from the lens to the sample using LIBS in conjunction with the following machine-learning algorithms to simulate plasma temperature: decision trees, support vector machine, Gaussian process regression, and neural network. The study compared the accuracy of these four algorithms before and after normalization based on the Cu (I) spectral line at 510.55 nm. All four algorithms achieved a correlation coefficient greater than 0.95 after normalization. The Gaussian process regression model provided excellent predictions before and after normalization with a correlation coefficient of 0.99, demonstrating the advantages of this model in plasma temperature simulation. This study confirmed that machine learning can effectively, conveniently, and accurately predict laser-induced plasma temperature, providing significant utility in LIBS research. [ABSTRACT FROM AUTHOR]

We consider the plasma made of relativistic electrons and positrons in thermodynamic equilibrium with photons at arbitrary temperature and degeneracy. We establish various thermodynamic identities as a function of the electron and positron chemical potentials and temperature. The high-temperature regime in which the electrons and positrons are ultrarelativistic is recovered. The excess of electrons with respect to positrons or the excess of positrons with respect to electrons depends on the thermodynamic conditions. Doing so, we go beyond what is usually found in the literature where only the high temperature regime is usually tackled. [ABSTRACT FROM AUTHOR]

In this investigation, a spectroscopic optical emission test was used to investigate the characteristics of gold plasmas that were produced in the surrounding environment using an Nd: YAG system at a wavelength of 1064 nm and had an energy output that varied from 400 to 600 mJ. The emission spectrum profiles of (Au) were analyzed and recorded using a spectrometer to aid in the extraction of vital plasma features (i.e., T e and n e ). Plasma temperature was determined using the Boltzmann plot method, and electron density was determined using the Stark broadening method. The temperature was between (0.91 and 0.94) eV, while the electron density ranged between (4.79 and 5.26) × 1 0 1 7 cm − 3 . The rest of the plasma parameters were calculated by the mathematical equations of the method used (Boltzmann Plott). [ABSTRACT FROM AUTHOR]

Flow ultrasound generators are devices that emit high-frequency sound waves due to the hydrodynamic instability of the supersonic flow. In the electric power industry, such generators are used in arc quenching systems of high-voltage gas blast circuit breakers. The design of the flow ultrasound generator includes a nozzle and a hollow cylindrical resonator. Self-oscillations of the sealing waves occur when a supersonic gas jet collides with a resonator. This article is devoted to the analysis of the arrester operation, which has design features of flow ultrasound generators. The paper includes both experimental investigations of the proposed spark gap arrester design and mathematical modeling of the processes occurring in it. A description of the methods used is presented, and a comparison of the time dependences of currents and voltages obtained as a result of experimental studies and as a result of calculations is performed in the next section. The calculation results include oscillograms of the voltage and current, and the plasma temperature distribution in the arrester chamber at different moments of time. The investigations show that the presence of a nozzle and resonator leads to an intensification of the gas dynamic effect on the electric arc. [ABSTRACT FROM AUTHOR]

The poor spectral stability of laser-induced breakdown spectroscopy (LIBS) seriously affects its analytical performance, which is a key obstacle to its further development. To overcome this challenge, an improved spectral standardization method based on plasma image-spectrum fusion (ISS-PISF) was proposed in this study. This method, for the first time, considers and quantifies the influence of plasma morphology on spectral intensity based on the line-integrated intensity formula of LIBS spectra. It recognizes that the spectral fluctuations mainly stem from variations in total number density, plasma temperature, electron number density, and plasma morphology. Therefore, ISS-PISF innovatively utilizes easily accessible features from plasma images and spectra to eliminate the influence of these four plasma parameters, thereby improving the spectral stability and analytical performance of LIBS. To validate the effectiveness of this method, the spectra of aluminum alloy samples obtained under complex detection conditions simulated by varying laser energy and defocusing amount were analyzed. After correction by ISS-PISF, the R2 for Mg I 516.73 nm, Mn II 294.92 nm, and Si I 288.16 nm improved to 0.990, 0.976, and 0.961, and the average RMSE of the validation set decreased by 46.154%, while the average STD of the validation set decreased by 37.405%. These experimental results indicate that this study provides a simple, effective, and physically supported spectral standardization method, which contributes to the further promotion and application of LIBS. [ABSTRACT FROM AUTHOR]

The high‐density transient plasma, streaming from a pulsed plasma accelerator (PPA), was diagnosed with a Triple Langmuir probe (TLP) for spatial mapping of the stream in terms of plasma density and temperature. A contour plot for density and temperature shows a distinct form of a highly dense island of plasma with varied plasma temperatures. The formation of such highly dense islands can be correlated with the formation of distinct plasma structures, as observed in astrophysical plasmas and fusion plasma. The results of TLP were supported by the intensity variation derived from signals of a photodetector system. The plasma stream imaged with high‐speed video camera also showed the density fluctuation inside the plasma stream. The estimated maximum density and temperature were ∼7.2 × 1020 m−3 and ∼28 eV, respectively. [ABSTRACT FROM AUTHOR]

The WHAMP (Rönnmark, 1982, https://inis.iaea.org/search/search.aspx?orig%5fq=RN:14744092) and LEOPARD (Astfalk & Jenko, 2017, https://doi.org/10.1002/2016ja023522) dispersion relation solvers were used to evaluate the growth rate and scale size for mirror mode (MM) and ion cyclotron (IC) instabilities under plasma conditions resembling Saturn's magnetosheath in order to compare observations to predictions from linear kinetic theory. Instabilities and waves are prevalent in planetary magnetosheaths. Understanding the origin and conditions under which different instabilities grow and dominate can help shed light on the role each instability plays in influencing the plasma dynamics of the region. For anisotropic plasmas modeled with bi‐Maxwellian particle distribution, the dispersion, growth rate, and scale size of MM and IC were studied as functions of proton temperature anisotropy, proton plasma beta, and oxygen ion abundance. The dispersion solvers showed that the IC mode dominated over MM under typical conditions in Saturn's magnetosheath, but that MM could dominate for high enough O+ ${O}^{+}$ abundance >40%ne $\left(> 40\%\ {\mathrm{n}}_{\mathrm{e}}\right)$. These water ion‐rich plasma conditions are occasionally found in Saturn's magnetosheath (Sergis et al., 2013, https://doi.org/10.1002/jgra.50164). The maximum linear growth rates γm/Ωp $\left({\gamma }_{m}/{{\Omega }}_{p}\right)$ for MM ranged from 0.02 to 0.2, larger than expected from observations. The scale size at maximum growth rate ranged from 4 to 12 ρp ${\rho }_{\mathrm{p}}$, smaller than expected from observations. These inconsistencies could potentially be attributed to diffusion and non‐linear growth processes. Plain Language Summary: Plasma instabilities have well‐defined relationships between the wavevector and the frequency captured in the dispersion relation. Linear kinetic theory provides a basis for interpreting instability growth rates and scale sizes in simulations and observations with small plasma fluctuations. However, it cannot describe the fate of the instability such as the maximum amplitude, nor its interactions with other modes. The ion cyclotron (IC) and mirror mode (MM) instabilities lead to fluctuations of different frequencies and spatial scales. Their growth occurs when the plasma exhibits temperature perpendicular‐to‐magnetic‐field greater than some threshold of the temperature parallel‐to‐magnetic‐field direction known as temperature anisotropy. Each instability has a role to play in influencing the plasma dynamics of the region. This study investigates the growth and scale size of IC and MM instabilities in conditions resembling Saturn's magnetosheath. Key Points: Dispersion solvers indicate ion cyclotron (IC) mode dominates over mirror mode (MM) at Saturn, but MM prevails with high O+ abundanceThe predicted MM linear growth rates at Saturn were 0.02–0.2, exceeding the inferred maximum rate of 0.008 from observationsThe scale size of MM at maximum linear growth rate was 4–12 ρp, smaller than the inferred size of 18–38 ρp from observations [ABSTRACT FROM AUTHOR]

This work presents a characterisation model for the temperature distribution at different substrate depths during the atmospheric plasma spray (APS) coating process. The torch heat flow in this model is simulated as forced convection defined by a surface, a temperature profile, and a convection coefficient. The simulation model considers three plasma temperature profiles of the Al2O3 coating on a 5 mm thickness flat aluminium substrate. The simple and low-cost experimental procedure, based on a thermocouple, measures the plasma plume temperature distribution of the APS coating system, and their results are used to obtain the parameter values of each of the three proposed plasma temperature profiles. The experimental method for in situ non-contact temperature measurements inside the substrate is based on an infrared pyrometry technique and validates the simulation results. The Gaussian temperature profile shows excellent accuracy with the measured temperatures. The Gaussian approach could be a powerful tool for predicting residual stress through a coupled one-way thermal-mechanical analysis of the APS process. [ABSTRACT FROM AUTHOR]

In this study, we have investigated the relationship between the plasma temperature in remote laser-induced breakdown spectroscopy (LIBS) experiments and the hydrophobic properties of silicone rubber insulators (SIRs). Contact angle and LIBS measurements were conducted on both artificially-aged (accelerated aging) and field-aged SIRs. This study reveals a clear connection between plasma temperature and the properties of aged SIRs on artificially-aged SIR specimens. Specifically, the plasma temperature exhibits a consistent increase with the duration of the accelerated aging test. The hydrophobicity of the artificially-aged SIRs was assessed by performing contact angle measurements, revealing a decrease in the hydrophobicity with increased aging test duration. Furthermore, we extended our investigation to the study of nine field-aged SIRs that had been in use on 150 kV overhead transmission lines for 0 to 21 years. We find that the laser absorption and hardness of the material do not relate to the plasma temperature. In summary, we observe a direct connection of plasma temperature to both contact-angle measurements and operation time of the in-service insulators. These results strongly suggest the potential use of LIBS for remotely evaluating the hydrophobicity and aging degree of silicone rubber insulators, thus assessing their real-time on-site operational quality. [ABSTRACT FROM AUTHOR]

A computationally efficient model is proposed to analyze plasma-assisted combustion using nanosecond repetitive pulsed (NRP) plasmas. The NRP plasma discharge is placed in the oxidizer stream of a counter-flow diffusion flame. The effect of changing the flow rate and the pulse repetition frequency (PRF) of a continuous NRP plasma discharge on the temperature and species profiles of a counter-flow diffusion flame is investigated numerically. The results confirm that oxygen atom and nitrogen vibrational states are the most important species to enhance combustion. The results also show that kinetic effects are much more significant for higher PRF and lower pulse voltage. In addition, when steady plasma profiles are used instead of unsteady plasma profiles, the extinction strain rates increase by 25.8%, 21.1%, and 10.8% for PRF equal to 1, 2, and 4 kHz, respectively. [ABSTRACT FROM AUTHOR]

Context. HESS J1702-420 is a peculiar TeV complex with a morphology changing from a diffuse source (HESS J1702-420B) at ≲2 TeV to a point-like one (HESS J1702-420A) at ≳10 TeV energies. The morphology and spectral properties of HESS J1702-420 could be understood in terms of (diffusive) hadronic or leptonic models in which the observed TeV emission arises correpondingly from proton-proton or IC-radiation of relativistic particles present in the region. Aims. In this work, we perform searches of the X-ray counterpart of the HESS J1702-420B source originating from the synchrotron emission of the primary or secondary relativistic electrons produced within leptonic or hadronic models. Such an emission can be extended and remain beyond the detection capabilities of narrow field-of-view instruments such as XMM-Newton. Methods. We utilised the publicly available first-6-months eROSITA dataset (DR1) fully covering the selected analysis region of > 5°-radius around HESS J1702-420. We discuss biases connected to variable plasma temperature or neutral hydrogen column density in the region and present results based on the background modelling approach. Results. The performed analysis does not allow us to detect the extended X-ray counterpart of HESS J1702-420 of 0.07° −3°-radii sizes. The derived upper limits are significantly higher than the expected hadronic model flux of the X-ray counterpart. For the leptonic model, the derived limits indicate the magnetic field in the region B ≲ 2 μG. We argue that further advances in the diffuse X-ray counterpart searches could be achieved with either next-generation missions or Msec-long observational campaigns using currently operating instruments. [ABSTRACT FROM AUTHOR]

One of the most significant medicinal plants used to treat numerous illnesses is Swertia chirayita. The present study demonstrated the compositional analysis of the Swertia chirayita (S. chirayita) plant using an emerging and non-destructive laser-induced breakdown spectroscopy (LIBS) technique. Mg, Ca, K, Fe, Sr, Cr, and Na were verified as necessary elements by the optical emission investigations, while Al, Ti, Si, Ba, Mn, and Li were non-essential. Using the Boltzmann plot technique with stark broadening parameters, plasma temperature and electron number density were calculated in the range of (10,000–12,000) K ±1000 K and (1.5–1.8) × 1017 cm-3, respectively. Finally, compositional analysis was carried out using calibration-free (CF-LIBS) analysis and results were compared with ICP-MS. It was observed that the concentration of Ca and Fe is higher than other detected elements. All the toxic elements are found to be within the safe limit. So, this medicinal plant can be used to cure a variety of diseases that arise due to the deficiency of these elements. [ABSTRACT FROM AUTHOR]

• The effect of temperature on plasma gasification of CPMW is explored experimentally. • A temperature of 1800 °C provides the optimum performance for air-CPMW gasification. • The volume fraction of H 2 and CO increases with the increased reactor temperature. Plasma gasification melting (PGM) provides reliable disposal of toxic medical waste with a low heating value, which is capable of converting waste into energy. This study investigates the performance of experiments on plasma gasification for the treatment of chemical-pharmaceutical medical waste (CPMW) with an air medium. A comparative analysis is performed for gasification characteristics at three reactor temperatures (1000, 1400, and 1800 °C). Moreover, a thermodynamic equilibrium model is developed to assess performance features such as syngas yield, high heating value, and cold gas efficiency in the gasification temperature range of 1000–1800 °C. A comparison of the experiment and computational outcomes shows a good agreement. The results show that the quality of syngas and heating value is improved by increasing the temperature of the plasma gasifier so that at 1800 °C, H 2 , CO, and higher heating value (HHV) are obtained as 41 %, 37 %, and 10 MJ/Nm3, respectively. The obtained syngas is a clean fuel with low sulfur-containing and nitrogen-containing. The experimental results provide an extensive comprehension of CPMW gasification in a plasma reactor and consider a possibility for hydrogen and energy production. [ABSTRACT FROM AUTHOR]

Copyright of Science & Technology of Food Industry is the property of Science & Technology of Food Industry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

AbstractThe accuracy of quantitative analysis in soil laser-induced breakdown spectroscopy (LIBS) is frequently compromised by self-absorption. Eliminating this influence is imperative for attaining reliable results. To mitigate the impact of self-absorption upon the determination of Cr in soil, a novel correction model based upon plasma temperature (SAT) is reported grounded in column density-Saha-Boltzmann (CD-SB) theory. This approach calculates plasma temperature using self-absorption spectra, thereby providing a foundation for line intensity calibration. Initially, the electron number density was determined using the full width at half maximum (FWHM) of the Hα 656.27 nm line. Subsequently, the column density of particles at lower energy levels and the plasma temperature were ascertained. Finally, a multi-line method was employed to correct for self-absorption. In comparison to the LIBS calibration curve procedure, the SAT model effectively rectifies self-absorption in the analysis of soil by significantly enhancing the linear determination coefficients (R2) of the Cr I 425.43 nm and Cr I 427.48 nm lines from 0.9569 and 0.9578 to 0.9869 and 0.9819, respectively. The model also reduces the exponential self-absorption factors by 2.1806 and 0.9919, respectively. The results demonstrate that the SAT model effectively rectifies self-absorption, thereby enhancing the accuracy for the quantitative analysis of soil. [ABSTRACT FROM AUTHOR]

Laser propagation in an electron-positron-ion (EPI) plasma medium having a constant density gradient is studied for the soliton evolution in the presence of a parallelly applied strong magnetic field. In a nonlinear regime, laser-plasma interaction forms an electron density hill that moves backward due to the density gradient. This hill localizes laser energy by the mechanism of resonance absorption (ωl = ωpe) and remains stable for a longer period, qualifying for the evolution of electromagnetic soliton. The position of the soliton from where it starts moving backward depends on the slope of the linear density variation. If the slope increases, then the position of the soliton is closer to the plasma boundary (x = 0). Another interesting property of the soliton is that its height decreases, and width increases as the temperature of plasma species rises. We simulate this phenomenon of electromagnetic soliton evolution in 1-D and 2-D by using Particle-In-Cell (PIC) simulation using the EPOCH-4.17.10. [ABSTRACT FROM AUTHOR]

A new method is proposed for measuring the electron plasma temperature at the GOL-NB facility. The method is based on measuring the ratio between the intensities of the spectral lines emitted by the fast atoms injected into the plasma. The beams of fast hydrogen atoms used for heating the plasma at the GOL-NB facility contain not only atoms with a full energy (E) but also atoms with fractional energies (E/2, E/3, E/18) that appear as a result of the dissociation of the H , H , and H2O+ molecular ions. The spectral lines of the beam components with these energies (and, in particular, the hydrogen Hα line) can be resolved due to the Doppler shift caused by the difference between the atom speeds. For atoms with low energy, the excitation that leads to the photon emission occurs only due to their collisions with thermal electrons, while for atoms with high energy, a sufficient deposition into their excitation is given by their collisions with the plasma ions. This is why the ratio between the intensities of the lines of different beam components depends on the plasma electron temperature, and thus, it can be used to measure this temperature. At the beam energy of 24 keV, the proposed method can be used to measure the electron temperature in the range of up to 40 eV, which is of interest for the current experiments conducted at the GOL-NB facility. Note that measurement of the electron temperature higher than 20 eV requires that the ratio between the spectral line intensities be measured with an accuracy of the order of one percent, and that the attenuation of the neutral beam that passes through the plasma be measured with the same accuracy. The proposed method can be used at other fusion facilities that use fast hydrogen atom injection to measure the temperature of the edge plasma. [ABSTRACT FROM AUTHOR]

The magnetospheric plasma (hot and thin) and the solar wind plasma (cold and dense) are separated by the Earth's magnetopause, in which plasmas of both origins coexist. Different types of plasma diffusions are found due to this plasma mixing, and kinetic Alfvén solitary waves (KASWs) are one of them. In this work, a theoretical approach is taken to study the fundamental properties of heavy ion acoustic KASWs (HIAKASWs) in a magnetized plasma system whose constituents are nonextensive q-distributed two temperature electrons with dynamical heavy ions. The perturbations of the magnetized collisionless plasma system are investigated using the reductive perturbation technique to deduce the Korteweg–de Vries (K–DV) and modified K–DV (MK–DV) equations to determine the fundamental characteristics of small, but finite amplitude HIAKASWs. The presence of nonextensive electrons, magnetic field, obliquity angle (the angle between the external magnetic field and wave propagation), plasma particle number densities, and the temperature of various plasma species are observed to significantly alter the fundamental properties of HIAKASWs. The findings of our present study may be useful for comprehending the nonlinear wave properties in diverse interstellar plasma environments. [ABSTRACT FROM AUTHOR]

We investigate the dynamics of plasma-based acceleration processes with collisionless particle dynamics and non-negligible thermal effects. We aim at assessing the applicability of fluid-like models, obtained by suitable closure assumptions applied to the relativistic kinetic equations, thus not suffering from statistical noise, even in the presence of a finite temperature. The work here presented focuses on the characterization of pressure anisotropies, which crucially depend on the adopted closure scheme, and hence are useful to discern the appropriate thermal fluid model. To this aim, simulation results of spatially resolved fluid models with different thermal closure assumptions are compared with the results of particle-in-cell simulations at changing temperature and amplitude of plasma oscillations. [ABSTRACT FROM AUTHOR]

Considering the effects of non-Maxwellian distributed electrons and the generation of magnetic field on the inertial confinement fusion driven by laser, the quasi-static magnetic field generated by nonlinear magnetization current in laser plasma with super-Gaussian distributed electrons is studied. Based on the kinetic theory, an analytical expression for the spontaneous magnetic field in Fourier space, valid for arbitrary frequencies, has been obtained. According to the existing experimental data, the effects of the frequency, plasma temperature, and super-Gaussian index on the spontaneous magnetic field are analyzed through numerical calculations. It is shown that the strength of the spontaneous magnetic field first decreases and then increases with the increase in the super-Gaussian index when the laser intensity is ∼ 10 12 W / cm 2 . It is about the order of 100 G, which is much smaller than the experimental observation. When the laser intensity is ∼ 10 16 W / cm 2 , the strength of the spontaneous magnetic field increases monotonically with the super-Gaussian index in the low-frequency region, and behaves similarly to the one of the laser intensity ∼ 10 12 W / cm 2 in the high-frequency region. It will be as large as megagauss, which is consistent with the experimental observation results. Moreover, the strength of the spontaneous magnetic field increases with the increase in frequency and the decrease in the electron temperature. [ABSTRACT FROM AUTHOR]

Singly charged background argide ions ArH+, ArN+, ArO+, and Ar2+ create strong spectral interferences in elemental and isotopic analysis by inductively coupled plasma mass spectrometry (ICP MS). In this study, we experimentally investigated the behavior of these ions depending on variations in high-frequency plasma power and argon carrier gas flow rate. Theoretical analysis was performed using thermodynamic modeling to predict the behavior of these argide ions on changes in plasma temperature and argon flow rate. Common patterns in the intensity of these major background ions and changes in their formation efficiency at different working parameters of the ICP are noted. A good agreement between the observed experimental dependences and those derived from thermodynamic models is noted. [ABSTRACT FROM AUTHOR]

In this research, the finite-element numerical software COMSOL Multiphysics is used to simulate the electric pulse rock-breaking process, and the novel numerical model takes into account the multiple fields of electrical, thermal, and mechanical physics. The electric field strength inside the rock under the action of the electric pulse is updated by the full coupling function of COMSOL (version 6.1) software, and the electric damage variable χ is used to describe the process of electric breakdown inside the rock, to simulate the formation of plasma channel in the process of electric pulse rock-breaking. The voltage change curves and plasma channel trajectories in the electric breakdown process of the model in this paper are compared with the literature to verify the accuracy of the model. The formation process of plasma channels captures the temperature and stress changes during the whole process of electric pulse rock-breaking, to reveal the mechanism of the electric pulse rock-breaking process. With the presence of conductive particles inside the rock, the particles can effectively promote the formation of plasma channels, increase the area of electrical damage, and improve rock-breaking efficiency. Before the formation of the plasma channel, the internal temperature of the rock is about 600 K, and the stress is about 10−2 MPa; when the channel is formed, the energy of the electric pulse is mainly concentrated in the plasma channel, and the temperature of the plasma channel rises to 104 K. When the maximum stress exceeds the critical stress of the rock, the rock undergoes fracture. Furthermore, an appropriate increase in the rise time of the electric pulse increases the speed and area of rock-breaking, subsequently improving the efficiency of rock fracture. The results of the numerical modeling in this paper help to better understand the mechanism of the electric pulse rock-breaking process, which is of great engineering significance for the development of new electric pulse rock-breaking technology in the realm of geotechnical engineering. [ABSTRACT FROM AUTHOR]

There is a lack of information about transforming growth factor beta-1 (TGF-β1) and cytokines contained in pure platelet-rich plasma (P-PRP) and release from pure-platelet-rich gel supernatants (P-PRGS) might be affected by the temperature and time factors; P-PRP from 6 heifers was activated with calcium gluconate. Thereafter, P-PRG and their supernatants (P-PRGS) were maintained at −80, −20, 4, 21, and 37 °C and collected at 3, 6, 12, 24, 48, 96, 144, 192, 240, and 280 h for subsequent determination of TGF-β1, tumor necrosis factor alfa (TNF-α), interleukin (IL)-2, and IL-6; TGF-β1 concentrations were significantly (p < 0.05) higher in PRGS maintained at 21 and 37 °C when compared to PRGS maintained at 4, −20, and −80 °C; PRGS TNF-α concentrations were not influenced by temperature and time factors. However, PRGS maintained at 4 °C showed significantly (p < 0.05) higher concentrations when compared to PRGS maintained at −20, and −80 °C at 144, and 192 h. IL-6 concentrations were significantly (p < 0.05) higher in PRGS stored at −20, and −80 over the first 48 h and at 10 days when compared to PRGS stored at 4, 21, and 37 °C. These results could suggest that P-PRP/P-PRGS could be maintained and well preserved for at least 12 days at room temperature for clinical use in bovine therapeutic massive protocols. [ABSTRACT FROM AUTHOR]

This work explores microcombustion technologies enhanced by plasma-assisted combustion, focusing on a novel simulation model for a Y-shaped device with a non-premixed hydrogen-air mixture. The simulation integrates the ZDPlasKin toolbox to determine plasma-produced species concentrations to Particle-In-Cell with Monte Carlo Collision analysis for momentum and power density effects. The study details an FE-DBD plasma actuator operating under a sinusoidal voltage from 150 to 325 V peak-to-peak and a 162.5 V DC bias. At potentials below 250 V, no hydrogen dissociation occurs. The equivalence ratio fitting curve for radical species is incorporated into the plasma domain, ensuring local composition accuracy. Among the main radical species produced, H reaches a maximum mass fraction of 8% and OH reaches 1%. For an equivalence ratio of 0.5, the maximum temperature reached 2238 K due to kinetic and joule heating contributions. With plasma actuation with radicals in play, the temperature increased to 2832 K, and with complete plasma actuation, it further rose to 2918.45 K. Without plasma actuation, the temperature remained at 300 K, reflecting ambient conditions and no combustion phenomena. At lower equivalence ratios, temperatures in the plasma area consistently remained around 2900 K. With reduced thermal power, the flame region decreased, and at Φ = 0.1, the hot region was confined primarily to the plasma area, indicating a potential blow-off limit. The model aligns with experimental data and introduces relevant functionalities for modeling plasma interactions within microcombustors, providing a foundation for future validation and numerical models in plasma-assisted microcombustion applications. [ABSTRACT FROM AUTHOR]

Plasma‐based CO2 conversion has attracted increasing interest. However, to understand the impact of plasma operation on post‐plasma processes, we studied the effect of adding N2, N2/CH4 and N2/CH4/H2O to a CO2 gliding arc plasmatron (GAP) to obtain valuable insights into their impact on exhaust stream composition and temperature, which will serve as feed gas and heat for post‐plasma catalysis (PPC). Adding N2 improves the CO2 conversion from 4 % to 13 %, and CH4 addition further promotes it to 44 %, and even to 61 % at lower gas flow rate (6 L/min), allowing a higher yield of CO and hydrogen for PPC. The addition of H2O, however, reduces the CO2 conversion from 55 % to 22 %, but it also lowers the energy cost, from 5.8 to 3 kJ/L. Regarding the temperature at 4.9 cm post‐plasma, N2 addition increases the temperature, while the CO2/CH4 ratio has no significant effect on temperature. We also calculated the temperature distribution with computational fluid dynamics simulations. The obtained temperature profiles (both experimental and calculated) show a decreasing trend with distance to the exhaust and provide insights in where to position a PPC bed. [ABSTRACT FROM AUTHOR]

The paper presents the results of the study of tungsten surface structure modification under helium plasma irradiation. It is revealed that during irradiation of samples, surface modification in the form of relief development as a result of irradiation is observed. X‐ray phase analysis showed that no new phases of the W system were found after irradiation, only an increase in the intensity of diffraction lines was observed. There are significant differences in the microstructure of tungsten depending on the temperature of helium plasma irradiation in the above range. It is assumed that the cause of defects is the extremely low solubility of helium in tungsten. Metallographic analysis has shown that at irradiation of tungsten samples in time modes 1 and 1.5 hours, the degree of relief development is not high in comparison with the tungsten sample irradiated in the 0.5‐hour mode. The greatest increase in surface roughness of the sample irradiated for 1 hour was registered, which is associated with the formation of small cracks, bubbles, and pores in the surface layer. At the same time, in the samples irradiated for 1.5 hours, the surface of which is characterized by chaotically located protrusions and depressions of various shapes, the roughness parameter Ra was 0.0603 μm. It was found that at temperature regimes T = 1200°C and T = 1500°C, the microhardness of tungsten increases by 10% and 11%, respectively. [ABSTRACT FROM AUTHOR]