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The performance characteristics of an argon propellant Hall thruster with two types of propellant injectors, the axial and swirl injectors, were investigated. In the swirl injector, the propellant is injected in the tangential direction. At a discharge voltage of 150 V, the swirl injector achieved a higher propellant utilization efficiency (30.3%) and anode efficiency (8.8%) compared to the axial injector (26.7% and 7%, respectively). A numerical simulation quantitatively explained the reason for these differences, which shows an increase in the neutral particle density of 32.6% near the injection region and 7.8% at the exit of the hollow anode with the swirl injector. Neutral particle accommodation on the anode wall was found to be the predominant mechanism, which reduces the injection effect. [ABSTRACT FROM AUTHOR]

A fundamental equation of state in terms of the Helmholtz energy is presented for mixtures of nitrogen, oxygen, and argon at any composition. It is expressed in terms of the residual Helmholtz energy and can be used to calculate all thermodynamic equilibrium properties including vapor–liquid equilibria. The parameters of the equations for the pure-fluid and mixture contributions are fitted exclusively to molecular simulation data so that the model has a predictive character. The description of the mixture-specific reducing parameters is realized via generalized correlations of the critical parameters of the pure fluids so that an extension of the model to additional components can be implemented straightforwardly. Extensive comparisons to experimental data and the GERG-2008 reference equation of state show that the prediction of thermodynamic properties is satisfactory. [ABSTRACT FROM AUTHOR]

For many years, the recombination of excited ions of argon, Ar + ( P 1 / 2 2 ) , has been assumed negligible under ambient conditions as compared to the recombination of ground-state ions, Ar + ( P 3 / 2 2 ). This opinion was confronted with detailed experimental results that seem to clearly support it. Here, we propose a new interpretation in light of our recent calculations, which shows that the recombination efficiency is comparable for both fine-structure states. Noteworthily, in our model leading to a picture consistent with the experiment, residual dimer ions emerge from A r + ( P 1 / 2 2 ) due to non-adiabatic dynamics effects and interplay in measured data. [ABSTRACT FROM AUTHOR]

Laser diode absorption spectroscopy is used to experimentally measure Ar(1s5) metastable density and translational gas temperature within a 94 GHz microplasma. A square two-dimensional photonic crystal (PhC) at this resonance frequency serves to ignite and sustain the plasma from 20 to 200 Torr (2.7 × 103–2.7 × 104 Pa) by using millimeter wave power from 300 to 1000 mW. Metastable density within the plasma is estimated from the absorption line shape of the laser traversing the PhC. The metastable density reaches an order of 1019 m−3 at lower pressure and decreases as pressure increases. From the Lorentzian line shape of the absorption profile at 811.53 nm, the gas temperature is extracted and found to increase from 500 K at 20 Torr to 1300 K at 200 Torr. These data are analyzed and compared with a zero-dimensional plasma model and with previous experimental plasma results at 43 GHz. [ABSTRACT FROM AUTHOR]

Shock tubes are instrumental in studying high-temperature kinetics and simulating high-speed flows. They rapidly increase the thermodynamic conditions of test gases, making them ideal for examining chemical reactions and generating high-enthalpy flows for aerodynamic research. However, non-ideal effects, stemming from factors like diaphragm opening processes and viscous effects, can significantly influence thermodynamic conditions behind the shock wave. This study investigates the impact of various diaphragm opening patterns on the shock parameters near the driven section's end wall. Experiments were conducted using helium and argon as driver and driven gases, respectively, at pressures ranging from 1.32 to 2.09 bar and temperatures from 1073 to 2126 K behind the reflected shock. High-speed imaging captured different diaphragm rupture profiles, classified into four distinct types based on their dynamics. Results indicate that the initial stages of diaphragm opening, including the rate and profile of opening, play crucial roles in the resulting incident shock Mach number and test time. A sigmoid function was employed to fit the diaphragm opening profiles, allowing for accurate categorization and analysis. New correlations were developed to predict the incident shock attenuation rate and post-shock pressure rise, incorporating parameters such as diaphragm opening time, rupture profile constants, and normalized experimental Mach number. The results emphasize the importance of considering diaphragm rupture dynamics in shock tube experiments to achieve accurate predictions of shock parameters. [ABSTRACT FROM AUTHOR]

In this work, the Yb2Si2O7 interphase was prepared on SiC fibers using the sol–gel method. The influence of sol concentration on the morphology of the interphase was discussed. After heat treatment in argon at 1200°C for 1 h, the Yb2Si2O7 was grown in situ on the fiber surface, forming an interphase layer. Then, SiCf/Yb2Si2O7/SiC minicomposites were prepared by chemical vapor infiltration (CVI). The Yb2Si2O7 interphase exhibited no changes throughout the high‐temperature preparation process and maintained stability and compatibility with the fiber and matrix. The tensile strength of SiCf/Yb2Si2O7/SiC minicomposites with Yb2Si2O7 interphase was significantly higher than SiCf/SiC minicomposites without interphase. The crack deflection, interfacial debonding, and fiber pullout were observed in the tensile fracture of the SiCf/Yb2Si2O7/SiC minicomposites. [ABSTRACT FROM AUTHOR]

Thermodynamic property data for solid argon have been analysed to construct a new fundamental equation of state (EOS) based on the Helmholtz energy. This approach is based on methodologies previously applied to solid CO2 and benzene (Trusler in J Phys Chem Ref Data 40:043105, 2011; Xiao et al. in J Phys Chem Ref Data 50:043104, 2021). The EOS is capable of predicting thermodynamic properties of solid argon up to 760 K and 6300 MPa, using temperature and cell volume as independent variables. The model incorporates the quasi-harmonic approximation with a Debye oscillator framework for vibrons, along with an anharmonic term to address deviations near the triple point. In addition to literature data, the model was regressed to new measurements of argon's solid cell volume conducted from (8 to 50) K using a high-intensity neutron diffractometer, the results of which are reported here. This new EOS achieves a high degree of accuracy in representing experimental data, with uncertainties (k = 1) estimated of 0.1 %, 0.5 %, and 0.5 % for the cell volume along the sublimation curve, along the melting curve, and in the compressed solid phase, respectively; 2 % to 10 % for the heat capacity along the sublimation curve in different temperature regions; 1 % to 10 % for the thermal expansivity on the sublimation curve; 2 % for the isothermal bulk modulus, 1 % for the isentropic bulk modulus, 0.2 % for the enthalpy of sublimation, 0.5 % to 2 % for the enthalpy of melting, 1 % for the sublimation pressure (T > 50 K), and 2 % to 5 % for melting pressure. The EOS maintains physically realistic behaviour across the range of conditions from absolute zero to high-pressure. [ABSTRACT FROM AUTHOR]

Photoresist ashing is one of the most common processing steps in semiconductor manufacturing. Conventional methods for photoresist ashing are wasteful, cause undesired damage, or lack the high throughput desired by industry. In this study, a large-area, atmospheric-pressure plasma source is studied for photoresist ashing. Etch rates of ∼200 nm/min are achieved using only argon and air, and no damage is introduced onto the underlying substrate. The ability to remove blanket and patterned photoresist films is demonstrated. [ABSTRACT FROM AUTHOR]

Purpose: The emulsification of silicone oil (SO) remains poorly understood. In the present study, we investigated the physical properties of unused pharmaceutical SO samples under various conditions. Moreover, clinical correlations with the patients' SO samples were assessed. Methods: Unused pharmaceutical ophthalmic SO samples and four explanted SO samples from previously vitrectomized patients with rhegmatogenous retinal detachment were analyzed. To assess the stability of SO, the samples were exposed to UV light, visible light, a green argon laser, microwave radiation, heat, and were aged. Following exposure, the samples were investigated using Fourier-transform infrared spectroscopy, optical transmittance and absorbance, and micro-viscometry measurements. Two patients underwent argon laser retinopexy while SO tamponaded the vitreous cavity postoperatively. Results: The physical properties of SO exposed to heat, UV light, microwave radiation, and aging did not change. However, SO irradiated by the green argon laser demonstrated a significant breakdown of atomic bonding and a transmittance loss. These results are consistent with the analyses of SO samples provided by patients. In those who underwent laser retinopexy, the SO exhibited clinical emulsification necessitating earlier removal, which was confirmed by physical tests. Conclusions: It may be postulated that patients exposed to the argon laser experienced more emulsification than the other two groups, leading to the earlier removal of the SO implants from the eyes. This investigation did not consider the biological effects of inflammatory biomarkers; however, it may provide valuable insights for optimizing the use of SO in ophthalmic surgery and other potential applications. [ABSTRACT FROM AUTHOR]

The dual-phase liquid argon time projection chamber is presently one of the leading technologies to search for dark matter particles with masses below 10 GeV c−2. This was demonstrated by the DarkSide-50 experiment with approximately 50 kg of low-radioactivity liquid argon as target material. The next generation experiment DarkSide-20k, currently under construction, will use 1,000 times more argon and is expected to start operation in 2027. Based on the DarkSide-50 experience, here we assess the DarkSide-20k sensitivity to models predicting light dark matter particles, including Weakly Interacting Massive Particles (WIMPs) and sub-GeV c−2 particles interacting with electrons in argon atoms. With one year of data, a sensitivity improvement to dark matter interaction cross-sections by at least one order of magnitude with respect to DarkSide-50 is expected for all these models. A sensitivity to WIMP–nucleon interaction cross-sections below 1 × 10−42 cm2 is achievable for WIMP masses above 800 MeV c−2. With 10 years exposure, the neutrino fog can be reached for WIMP masses around 5 GeV c−2. The DarkSide-20k collaboration reports the sensitivity of its detector, currently under construction, to models predicting light dark matter particles. This includes Weakly Interacting Massive Particles and particles interacting with bound electrons of argon atoms. [ABSTRACT FROM AUTHOR]

A self-consistent model of inductively coupled plasma (ICP) discharge in argon describing the main plasma parameters at medium and high pressures was formulated in the work. Numerical calculations were carried out in a wide range of discharge conditions. Deviations from the fulfillment of similarity laws for some parameters for geometrically similar discharge tubes are shown. [ABSTRACT FROM AUTHOR]

The work carried out numerical calculations to study the dynamics of plasma-chemical processes in a glow discharge in argon with small admixtures of methane CH4 at low pressures. The dynamics of changes in the main conversion products and various types of ions in the process of establishing a discharge are presented. It is shown that the time it takes for the conversion products to reach a stationary regime is about t = 8 s. The main products of methane conversion in steady state are atomic hydrogen, as well as atomic and molecular carbon. [ABSTRACT FROM AUTHOR]

The application of the entropy-driven and density-driven phase transitions for analysis of phase diagram of water and argon is discussed. The reduced coefficient of isothermal compressibility is evaluated as βr = –(dV/dP)T(Pc/Vc) (Pc and Vc are the values in the critical point). The data are presented as dependencies of βr on the reduced temperature T/Tc, pressure P/Pc, and chemical potential μ/μc. Consideration is based on the principle of corresponding states. For water, the regions with anomalous behavior associated with the entropy-driven liquid–hexagonal ice phase transition and minima observed at T = (315.3 ± 0.2) K, P = (8.30 ± 0.04) kPa, and μ = (1122 ± 5) kJ/kg. For water, the baric dependence βr(P/Pc) along the liquid–vapor equilibrium line forms a closed loop with line of the liquid–hexagonal ice equilibrium. The thermodynamic similarity of water and argon is observed at relatively large temperatures T/Tc > 0.56, pressures P/Pc > 0.00358, and chemical potentials μ/μc > 0.505. [ABSTRACT FROM AUTHOR]

In this study, we explore high harmonic generation (HHG) in pure argon (Ar) gas and a mixture of argon and helium (He). We investigate phase-matching conditions and interference effects in both single and mixed-gas systems. By varying the gas pressure in the Ar–He mixture, we optimize the harmonic spectrum, achieving a broad range from H17 to H43, corresponding to photon energies of 25 eV to 75 eV. We attribute the spectrum broadening to a cascaded HHG process: argon-generated extreme ultraviolet photons excite helium's outer electrons, which are then driven by the fundamental laser field to contribute to HHG. This finding aligns with previous studies, showing that mixing gases with low and high ionization potentials can enhance HHG. The results offer a broad HHG spectrum ideal for ultra-fast spectroscopy and high-resolution imaging applications. [ABSTRACT FROM AUTHOR]

This study investigates the ionization pressure threshold of a gas (air, helium, argon, and SF6 across a wide pressure range) filled dielectric tube when a ∼300 MW, ∼0.7 ns, 9.6 GHz high-power microwave (HPM) pulse propagates through it. The thresholds are determined as the pressure for which the energy of the transmitted HPM pulse decreases to ∼30%, which is close to the same HPM pulse's transmission coefficient when a metal rod fills the tube. These thresholds are found to be 0.4 × 105 Pa,105 Pa, 1.8 × 105 Pa, and 0.2 × 105 Pa, for air, argon, helium, and SF6, respectively. The measured intensity of the plasma light emission starts to decrease at a pressure which coincides with the pressure threshold determined by HPM pulse propagation. Additionally, at gas pressures <5 × 104 Pa, it is shown that time- and space-resolved images of the light emission display a diffused plasma which at higher pressures >105 Pa transforms into streamer like plasma. Simplified numerical simulations of a microwave discharge in air at 1 × 105 Pa and 4 × 105 Pa are consistent with the experimental plasma light observations. [ABSTRACT FROM AUTHOR]

The noble gas argon is one of the most promising neuroprotective agents for hypoxic-reperfusion injuries of the brain. However, its effect on traumatic injuries has been insufficiently studied. The aim of this study was to analyze the effect of the triple inhalation of the argon-oxygen mixture Ar 70%/O2 30% on physical and neurological recovery and the degree of brain damage after traumatic brain injury and to investigate the possible molecular mechanisms of the neuroprotective effect. The experiments were performed in male Wistar rats. A controlled brain injury model was used to investigate the effects of argon treatment and the underlying molecular mechanisms. The results of the study showed that animals with craniocerebral injuries that were treated with argon inhalation exhibited better physical recovery rates, better neurological status, and less brain damage. Argon treatment significantly reduced the expression of the proinflammatory markers TNFα and CD68 caused by TBI, increased the expression of phosphorylated protein kinase B (pAKT), and promoted the expression of the transcription factor Nrf2 in intact animals. Treatment with an argon-oxygen breathing mixture after traumatic brain injury has a neuroprotective effect by suppressing the inflammatory response and activating the antioxidant and anti-ischemic system. [ABSTRACT FROM AUTHOR]

Recently (2024), the NA61/SHINE collaboration has presented new experimental data on , , proton, and antiproton productions in central 40Ar + 45Sc collisions at the laboratory momenta Plab = 13–150 A GeV/c and has compared these data with predictions of popular theoretical models. It turned out that the models poorly describe the data in the entire energy range. In this work, it has been suggested for the first time that nucleons participating in non-diffractive collisions cannot diffractively dissociate in subsequent nucleon–nucleon collisions. This idea has been implemented in the Geant4 FTF model. Good description of the data, including the first NICA BM@N data on meson production in the collisions of 40Ar nuclei with various nuclei at an energy of 3.2 A GeV, has been achieved. [ABSTRACT FROM AUTHOR]

The primary objective of this study was to investigate the pharmacokinetics of inhaled argon in young pigs using mechanical ventilation. Also a physiologically based model of argon pharmacokinetics (PBPK) is validated with human data for xenon from the literature and the new data from juvenile pigs. The inherent difficulty in performing pharmacokinetics studies of argon makes the use of the PBPK model especially relevant. The model is used to investigate argon pharmacokinetics for adult and neonate applications. Juvenile pigs (n = 4) were anesthetized, submitted to endotracheal intubation, and mechanical ventilation using a conventional ventilator. Argon inhalation was achieved by switching the animal from the first mechanical ventilator (with air/oxygen) to a second one that was supplied with 75% argon and 25% oxygen from premixed gas cylinders. This administration yielded blood samples that were analyzed using a quadrupole based technique for determining argon concentration. The range of blood:gas partition coefficient corresponding to the average measured Cmax of 190–872 μM is 0.005–0.022. Based on the average curve, T1/2= 75 seconds. The PBPK is shown to be in general agreement with the experimental data in pigs. Inhaled argon administration exhibited an on-off nature such that AUC was proportional to administration time. Confidence in the PBPK model and the remarkably robust and stable on-off nature of argon pharmacokinetics, notwithstanding intersubject variability and comorbidity, suggests that inhaled argon could readily be applied to any treatment regime. [ABSTRACT FROM AUTHOR]

Analysis of the effect of argon bottom blowing on stirring and refining in a ladle was carried out using numerical simulation based on a 250-ton ladle. The flow field inside the ladle was calculated for different bottom-blowing hole angles and radial positions, and the influence of the distance between the bottom-blowing holes and refining effect was investigated. The results indicate that as the bottom-blowing flow rate increases, the rate of change in the dead zone inside the ladle gradually decreases and drops sharply at 950 L/min. When the angle between the two bottom-blowing holes increases from 90° to 180 ° under the same bottom-blowing flow rate, the maximum velocity at the steel-liquid interface decreases and the average flow velocity of the steel liquid increases. When the bottom-blowing aperture is at a position of r/R = 0.5, the stirring effect of the steel liquid is good, and when r/R = 0.67 is arranged. When the spacing ratio is constant, the relative position changes, and the bottom-blowing effect hardly changes. When the spacing ratio increases from 0.707 to 1, the mixing effect of the steel liquid improves, and the refining effect of the steel-liquid interface decreases. [ABSTRACT FROM AUTHOR]

This work studied the rovibrational absorption spectral line-shape parameters of the P(1)–P(10) and R(0)–R(9) lines for Hydrogen fluoride perturbed by argon in the 0–0, 1–0, and 2–0 vibrational bands at 20–1000 K. A dataset of beyond-Voigt line-shape parameters (pressure broadening and shifting parameters, their speed dependencies, and the complex Dicke parameters) has been theoretically determined for the first time from generalized spectroscopic cross-section calculated by the full quantum scattering calculations. Then these parameters were employed to predict the line shape and asymmetry based on the partially-correlated speed-dependent hard-collision and the partially-correlated quadratic-speed-dependent hard-collision profiles. The effect of each parameter on the line shape and line asymmetry was further studied, which revealed that the beyond-Voigt effects were indispensable to accurately describe the line shape contour. Our results are in good agreement with the available experimental observations and provide a comprehensive set of theoretical references for further experimental measurements. [ABSTRACT FROM AUTHOR]

Diode-pumped rare gas lasers (DPRGLs) have the potential for high-energy laser output with high beam quality. The metastable concentration >1014 cm−3 and pump intensity >10 kW/cm2 are required in developing high-power and efficient DPRGLs. However, the kinetics of 1s and 2p levels (Paschen notation) under these conditions is unclear yet, particularly regarding the adverse effects of interference energy levels (e.g., 1s4 and 2p1–2p8). This study addresses this gap by measuring the number densities of 1s and 2p levels in a diode-pumped plasma jet metastable argon laser. The experiment was conducted with a much higher number density of 1014 cm−3 and a higher pump intensity of 12 kW/cm2 than our previous works. The results indicate that the adverse effect of 1s4 accumulation could be partially compensated, and the relative population distribution of 2p energy levels remained unchanged. However, the high gas temperature (>1000 K) caused a significant negative impact of high 2p levels (2p1–2p8), and the air environment weakened the effect of He collision relaxation. [ABSTRACT FROM AUTHOR]

The importance of microwave device reliability and performance for microscale devices motivates a more fundamental understanding of breakdown mechanisms in this regime. Microwave breakdown theories predict breakdown when electron production balances electron loss. Electron production depends strongly on the ionization rate ν i ; however, previous studies either used the measured ν i in macroscale gaps or the empirical formula for DC voltage, inaccurately predicting ν i in microscale gaps. Alternatively, this work characterizes ν i in microwave microplasmas by using particle-in-cell simulations. We calculated ν i in argon gas at atmospheric pressure for 2–10 μm gaps under AC fields ranging from 1 to 1000 GHz. The behavior of ν i may be separated into two regimes by defining a critical frequency f c r that depends on the amplitude of the applied voltage, gap distance, and pressure. For frequency f < f c r , the electrodes collect the electrons during each cycle and the electron number oscillates with the electric field, causing ν i / f to roughly scale with the reduced effective field E e f f / p. For f > --> f c r , the phase-space plots indicate that the electrons are confined inside the gap, causing the electron number to grow exponentially and v i / p to become a function of E e f f / p. These results elucidate the ionization mechanism for AC fields at microscale gap distances and may be incorporated into field emission-driven microwave breakdown theories to improve their predictive capability. [ABSTRACT FROM AUTHOR]

The second-order optical nonlinearity (SON) of thermally poled fused silica was shown for the first time to be significantly improved by the implantation of multi-energy boron (B) ions, and the outcomes were compared with those obtained from the implantation of multi-energy argon (Ar) ions. Second-harmonic (SH) signals in both samples grew roughly linearly as the poling temperature rose. Samples with Ar implants showed a greater increase in SH signal with rising poling temperature. A qualitative explanation for the formation of χ (2) in poled samples can be found in a model of charge hopping and migration through defects. The diminished SH signal in the B-implanted sample is probably caused by the negative charge trapping layer, as well as by B 2 α and E ′ center defects. [ABSTRACT FROM AUTHOR]

High-temperature annealing (HTA) is one of the most promising techniques to produce high-quality, cost-efficient AlN templates for further epitaxial growth of AlGaN devices. Unfortunately, the yield of this process seems to be limited due to the restricting face-to-face configuration that is typically used, in which contaminations of the template surface can occur easily. A high yield is crucial for process transfer into industry. Indeed, templates that are annealed in open-face configuration suffer from surface degradation due to excessive AlN evaporation during the course of the annealing process. To highlight the physics that are restricting the open-face approach of the process, sublimation behavior of AlN at temperatures and atmospheres typically used in HTA processes has to be examined. In this study, we use the Knudsen effusion mass spectrometry technique to confirm the previously published results on equilibrium partial pressures of species above AlN. Based on the experimentally determined data and further AlN sublimation experiments, the apparent sublimation coefficient of AlN in N2 and Ar atmospheres at HTA process conditions can be derived. Despite N2 having a stabilizing effect on AlN during HTA, the still high decomposition rates of several hundred nanometers per hour can explain the excessive damage that is typically observed if AlN/sapphire templates are annealed in an open-face configuration. Finally, based on theoretical considerations, a strategy to reduce the sublimation of AlN during HTA in open-face configuration is suggested. [ABSTRACT FROM AUTHOR]

Inert gas argon has important applications in the fields of daily life, industrial manufacture and nuclear environmental monitoring. The key to its application is to selectively and efficiently separate and purify Ar from complex gas components. However, the separation of O2 and Ar at normal temperature is full of challenge due to their similar molecular sizes and adsorption properties as well as their close boiling point. In industry, high purity Ar is mainly produced by low temperature rectification, which is mature technology, but the equipment is large, high-energy consumption and explosive. Adsorption separation is a common method of gas separation. Molecular sieves are the most widely used material due to their huge specific surface area, aboudant pore structure and excellent adsorption properties. The silica tetrahedron in molecular sieve is electrically neutral, while the aluminum tetrahedron is electronegative, which makes it necessary to use H+ or Na+ outside the molecular sieve skeleton to maintain electrical neutrality. In actual application, the interaction between adsorbent and adsorbent can be enhanced by ion-exchange modification of molecular sieve material, so as to effectively improve the O2/Ar separation capacity of molecular sieve. In this paper, the application of ion-exchange modified molecular sieve materials in the field of O2/Ar adsorption separation was systematically summarized and reviewed. The results show that the O2/Ar separation coefficients of molecular sieves modified by alkaline earth metal ions like Ca2+, Sr2+ and Ba2+ can reach about 2.0, while that of Ce3+-exchanged X-type molecular sieve is as high as 5.9, it is an ideal adsorption material for O2/Ar separation. However, the high separation coefficient is limited to the range of low partial pressure, and the O2/Ar separation coefficient under normal pressure is below 2.0. The Ag+-exchanged molecular sieves, namely silver-loaded molecular sieves, have excellent Ar adsorption selectivity. At present, the O2/Ar separation coefficients of silver-loaded molecular sieve materials at atmospheric pressure are around 2.0, but the preparation cost of silver-loaded molecular sieves is high, and it is more suitable for small-scale separation applications, it means that the efficient separation of O2 and Ar at normal temperature and pressure is still challenging. The development of novel ion-exchange modified molecular sieve materials with high adsorption capacity and high adsorption selectivity for the separation of O2 and Ar is still one of the focuses and trends of future research projects.

The paper presents the results of the study of the processes of self-propagating high-temperature synthesis of Zr-1%B alloy and its refining by electron beam melting. Experiments on the influence of boron’s amorphous and crystalline modifications on the safety parameters of the synthesis process of Zr-1%B alloy necessitated the conversion of amorphous boron into crystalline form by electron beam melting, with an increase in its purity from 94% to 99.9%. High efficiency of vacuum induction and electron beam equipment was demonstrated, which provided a high purity of the Zr-1%B alloy of at least 99.9%. The alloy ingots had a uniform distribution of the alloying element (boron) all over the volume. The obtained alloy is suitable for the production of materials with thermal neutron capture cross-sections of up to 40 barns for neutron protection.

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]

The thermodynamic constraints of steel deoxidation are discussed based on calculated [%Me]–[%O] diagrams for different deoxidizing elements in pure Fe and five examples of steel grades, highlighting the influence of alloying on the equilibria. The role of deoxidation product oxides is considered with special emphasis on the activity of SiO2 and the possibility of utilizing slags with a very low aSiO2 to amplify the deoxidizing power of silicon. This effect was verified for SiCr spring steel and 18Cr8Ni stainless steel. The results indicate a strong reduction in equilibrium oxygen content. Different means for industrial implementation of this principle are discussed. The conventional steel/slag equilibration via gas stirring is tested in practice. As potentially more efficient methods, slag powder injection (argon, lance) and cored wire injection combined with argon bubbling are studied. In such treatments, specific tailored slag additives can be used for divergent steel grades to optimize steel cleanliness and inclusion engineering. [ABSTRACT FROM AUTHOR]

Chemiluminescence of OH∗ is commonly employed as an optical indicator for the combustion process. It is widely recognized that the generation of OH∗ in hydrogen flames is primarily governed by the reaction H + O + M=>OH∗+M. In this study, the time histories of OH∗ chemiluminescence from the A→X band around 308 nm were recorded behind reflected shock waves for stoichiometric and lean H 2 /O 2 mixtures highly diluted in argon over the temperature range of 1130–3150 K and at the pressure of approximately 0.9 atm. Based on the time histories of OH∗ chemiluminescence, the best-fit reaction rate coefficient for the reaction H + O + M=>OH∗+M was determined as k = 3.17 × 1027exp(-121968 cal mol−1/RT) + 2.25 × 1017exp(-4246 cal mol−1/RT) cm6 mol−2 s−1 over the temperature range studied. Furthermore, by using the current rate coefficient in mechanism predictions, the predicted time histories and relative peak intensities of OH∗ chemiluminescence are in good agreement with experimental results reported in literature. • The time histories of OH∗ chemiluminescence up to 3150K are recorded. • The rate coefficient for H + O + M=>OH∗+M is determined. • The OH∗ sub-mechanism with the fitted rate coefficient has been verified. [ABSTRACT FROM AUTHOR]

Since the last century, it has been known that inert gases can cause a range of physiological effects. The biological activity of inert gases is an extremely multifaceted phenomenon. Despite the similarity of most physical and chemical characteristics, they differently influence many organs and tissues by interacting with a variety of protein targets. Xenon, krypton, and argon are now known to be capable of altering the functional state of the central nervous system and correcting some psychoemotional disorders. In addition, noble gases act on the processes of apoptosis and cellular stress response, affect the immune status and various homeostatic parameters. The cytoprotective effects of helium on the cardiovascular and respiratory systems have also been convincingly demonstrated. Thus, inert gases are currently being considered as potential tools to correct various diseases. This review analyzes literature data on the physiological effects of inert gases, as identified in biomedical studies on patients, as well as in cell culture and in vivo models. Each chapter is dedicated to a particular gas of this group, starting from the most studied. For each of the inert gases (helium, neon, argon, krypton, xenon, and radon), the physiological activity, possibility of being used in medicine, and some known mechanisms of its action are considered. Moreover, the existing data are critically analyzed, and the key gaps to be filled in future research are highlighted. [ABSTRACT FROM AUTHOR]

The study aims to comprehend the behavior of nitrogen in the argon oxygen decarburization (AOD) process during the production of nitrogen‐alloyed stainless steels, where the precise adjustment of nitrogen content plays a crucial role in enhancing productivity. Furthermore, the objective is to investigate the rate of change in nitrogen content when blowing a mixture of nitrogen and argon, instead of using pure nitrogen or argon alone. Hence, both nitrogenation and denitrogenation cases are examined, and kinetic models are developed. While solution thermodynamics can predict the final nitrogen content, the kinetics are influenced by the gas flow rate, steel temperature and composition, and levels of the surface active elements in the steel. By integrating a previously developed thermodynamic equilibrium equation with the kinetic models, nitrogen contents in the range of 0.150–0.400% can be reliably predicted. Consequently, the equations can be applied to predict nitrogen content during both the nitrogenation and denitrogenation stages in the reduction and desulfurization phases of the AOD process. [ABSTRACT FROM AUTHOR]

Wood–plastic composites (WPCs) combine the properties of plastics and lignocellulosic fillers. A particular limitation in their use is usually a hydrophobic, poorly wettable surface. The surface properties of materials can be modified using ion implantation. The research involved using composites based on polyethylene (PE) filled with sawdust or bark (40%, 50%, and 60%). Their surfaces were modified by argon ion implantation in three fluencies (1 × 1015, 1 × 1016, and 1 × 1017 cm−2) at an accelerating voltage of 60 kV. Changes in the wettability, surface energy, and surface colour of the WPCs were analysed. It was shown that argon ion implantation affects the distinct colour change in the WPC surface. The nature of the colour changes depends on the filler used. Implantation also affects the colour balance between the individual variants. Implantation of the WPC surface with argon ions resulted in a decrease in the wetting angle. In most of the variants tested, the most significant effect on the wetting angle changes was the ion fluence of 1 × 1017 cm−2. Implantation of the WPC surface also increased the surface free energy of the composites. The highest surface free energy values were also recorded for the argon ion fluence of 1 × 1017 cm−2. [ABSTRACT FROM AUTHOR]

To investigate the impact of energy release of reactive material on its damage effect, a modified test chamber was developed to conduct vented chamber tests and penetration tests in both air and argon environments of Al/Ti and Al/TI/W reactive projectiles. The deformation volumes obtained from the scanning results were employed to characterize the damage effect of the reactive materials on multi-spaced plate targets. Several key results include the following: Despite its lower energy density, the Al/Ti/W composite exhibits higher energy release efficiency than the Al/Ti composite. This is attributed to the lower strength of the material, causing it to fragment into finer debris upon impact, thereby facilitating easier ignition and reaction. The Al/Ti/W projectiles induce a significant deformation volume in the plates during penetration tests but exhibit a decrease in penetrative capacity. This phenomenon is attributed to the mechanical characteristics of the Al/Ti/W materials rather than the energy release upon impact. The deflagration of reactive materials during impact does not significantly enhance the structural damage of the target, at least at impact velocities below 1200 m/s. [ABSTRACT FROM AUTHOR]

The original Rosenfeld–Tarazona (RT) scaling of the excess energy in simple dense fluids predicts a ∝ T 3 / 5 thermal correction to the fluid Madelung energy. This implies that the excess isochoric heat capacity scales as C v ex ∝ T − 2 / 5 . Careful examination performed in this paper demonstrates that the exponent − 2 / 5 is not always optimal. For instance, in the Lennard-Jones fluid in some vicinity of the triple point, the exponent − 1 / 3 turns out to be more appropriate. The analysis of the specific heat data in neon, argon, krypton, xenon, and liquid mercury reveals that no single value of the exponent exists, describing all the data simultaneously. Therefore, we propose a generalized RT scaling in the form C v ex ∝ T − α , where α is a density- and material-dependent adjustable parameter. The question concerning which material properties and parameters affect the exponent α and whether it can be predicted from general physical arguments requires further investigation. [ABSTRACT FROM AUTHOR]

A multiphase mathematical model was established to study the fluid flow, the open-eye formation, and the residence time of slag inclusions in a bottom argon-blowing ladle. The fluid flow was solved using the Eulerian-Lagrangian multiphase approach, and the interface between different phases was described using the Volume of Fluid (VOF) model. The motion of argon bubbles and slag inclusions was tracked with the method of the discrete phase model (DPM). Moreover, the composition transformation of slag inclusions was predicted by employing a kinetic model based on the coupled reactions model. Numerical results show that the flow of the molten steel and the open-eye of the molten slag were sensitive to the argon blowing rate. The larger argon blowing rate expanded the volume of the plume and the area of the open-eye. Slag droplets were considered to move with the steel to the region away from the open-eye and then entrained into the steel to form slag inclusions as there was barely any downward velocity around the open-eye. Most slag inclusions were able to be removed immediately after the entrainment, while there still were some slag inclusions retaining in the steel for as long as thousands of seconds. The composition of slag inclusions had an apparent transformation due to reactions with the steel. The content of SiO2 and MgO in slag inclusions had a decrease while that of Al2O3 rose remarkably. The variation of SiO2 content occurred in the early one minute and the MgO content reduced gradually from 7.34wt% to 1.12wt% in 10 min. The composition transformation of slag inclusions was basically completed within 10 min in the current case. [ABSTRACT FROM AUTHOR]

This study, investigated the powder flow field for multiangle laser cladding, bridging theoretical gaps in the repair of metal parts with tilted and complex surface, specifically those are immovable and nonrotatable. Initially, a multiangle computational fluid dynamics-discrete element method gas-powder coupling model was established. It can consider not only the continuity characteristics of gas as a fluid, the discreteness characteristics of powder as particles, but also the mutual influence relationship. Subsequently, the response surface method was used to explore the optimal combination of carrier argon gas rate (A), the powder-feeding rate (B), and the protective argon gas rate (C) at different deflection angles, with the powder collection rate as the optimization objective. Analysis of variance results for the powder collection rate indicated that the significance of the factors and their interaction terms were ranked as A > B > AB at 0° and 30°, A > B > BC at 60°, A > B > C > BC at 90°, and C > A > BC > AB at 120° and 150°. Furthermore, the relative errors between predicted and simulated values, as well as simulated and powder collection experimental values, the single-pass experimental values were within 2%, 3%, and 7%, indicating the model was valid and reliable. Finally, the optimal combinations of carrier argon gas rate, powder-feeding rate, and protective argon gas rate were obtained, achieving high powder collection rates. These research findings offer theoretical guidance for selecting and optimizing process parameters in multiangle laser cladding. [ABSTRACT FROM AUTHOR]

The effect of the initial atoms distribution on the molecular dynamics (MD) simulation of a model atomic fluid (argon) is investigated for the case of the isochoric phase transition to the supercritical state. In particular, the case of uniformly distributed atoms in the simulation domain is compared with the case of separated liquid and vapor atoms. The sensitivity of simulations to asymmetric nanoscale perturbations in the boundary is also studied. Despite its high computational cost, the MD approach has the potential to successfully address long‐standing problems in computational fluid dynamics (CFD), especially those associated with mathematical singularities, such as contact angles, vortices, phase transitions and so forth. Unlike conventional CFD simulations, where the initial condition is the pressure or velocity distribution in the simulation domain, MD simulations also require the initial position of each molecule. Thus, it is important to understand whether a judicious choice of the initial distribution of molecules can reduce the overall computation time of the simulation. The evolution of the model fluid system during the phase transition was simulated using a Lennard‐Jones interatomic potential, corrected with the Lorentz–Berthelot mixing rule for the interactions with the solid walls. The system was allowed to relax until equilibrium, and then a Heaviside temperature step was applied to the wall to bring the system to supercritical conditions. Results show the initial choice of the atoms distribution can significantly affect the computational time, while the effect of asymmetric perturbations on the boundary is negligible. [ABSTRACT FROM AUTHOR]

Plasma-catalysis has attracted significant interest in recent years as an alternative for the direct upgrading of methane into higher-value products. Plasma-catalysis systems can enable the electrification of chemical processes; however, they are highly complex with many previous studies even reporting negative impacts on methane conversion. The present work focuses on the non-oxidative plasma-catalysis of pure methane in a Dielectric Barrier Discharge (DBD) reactor at atmospheric pressure and with no external heating. A range of transition and noble metals (Ni, Fe, Rh, Pt, Pd) supported on γ-Al2O3 are studied, complemented by plasma-only and support-only experiments. All reactor packings are investigated either with pure methane or co-feeding of helium or argon to assess the role of noble gases in enhancing methane activation via energy transfer mechanisms. Electrical diagnostics and charge characteristics from Lissajous plots, and electron temperature and collision rates calculations via BOLSIG+ are used to support the findings with the aim of elucidating the impact of both active metal and noble gas on the reaction pathways and activity. The optimal combination of Pd catalyst and Ar co-feeding achieves a substantial improvement over non-catalytic pure methane results, with C2+ yield rising from 30% to almost 45% at a concurrent reduction of energy cost from 2.4 to 1.7 and from 9 to 4.7 . Pd, along with Pt, further displayed the lowest coke deposition rates among all packings with overall stable product composition during testing. [ABSTRACT FROM AUTHOR]

Featured Application: Development of ultrapure materials technology. We demonstrate measurements of the absorption coefficient α ≈ 2.5 × 10−7 cm−1 in synthetic crystalline quartz at a wavelength of 1071 nm with a signal-to-noise ratio of 10/1 using the Time-resolved photothermal common-path interferometry (TPCI) scheme. It utilized cells filled with flowing argon and eliminated the influence of ambient air absorption. The scheme elements limiting the sensitivity of measurements at the level of ≈7.8 × 10−8 cm−1 were revealed. When these elements are replaced by better ones in terms of their thermal influence, the sensitivity of absorption coefficient measurements in crystalline quartz is ~10−8 cm−1. The calculation of the correction due to these optical elements of the values of the measured absorption coefficients is also described, which makes it possible to achieve the same sensitivity without replacing the elements. The improved scheme confirms the presence of the spatial inhomogeneity of absorption with a minimum coefficient of 2.5 × 10−7 cm−1 in synthetic crystalline quartz. The discrepancy of the absorption coefficient values in different regions of the crystal in the presented series of experiments was 2.5 × 10−7 cm−1 to 4 × 10−6 cm−1. Taking into account the ratio of thermo-optical parameters and the heat diffusion effect, the calculation shows that for quartz glasses the corresponding sensitivity of the absorption coefficient measurements equals ≈1.5 × 10−9 cm−1. [ABSTRACT FROM AUTHOR]

In this paper, the dissolution behavior of crystal-originated particle (COP) in 300 mm Czochralski silicon under argon annealing was investigated. The latex sphere equivalent size distributions of defects along the depth direction in silicon wafers annealed under different conditions were quantified utilizing chemical–mechanical polishing and localized light scattering inspection. The interstitial oxygen concentration profiles were quantified by secondary ion mass spectrometry, and the distributions of oxygen precipitation within annealed wafers were obtained based on peak analysis. Furthermore, the classical theoretical model was employed to elucidate the depth-dependent dissolution of COP. Based on the initial COP sizes and oxygen concentrations, the relationship between COP sizes and depth after annealing was calculated. The depth distributions of defects obtained by combining the dissolution of COP from calculation with the changes of oxygen precipitation were found to be highly consistent with the measurement results. These findings could enhance the understanding of the mechanism of COP dissolution, which contributes to the production of defect-free silicon wafers for nanometre-scale integrated circuits. [ABSTRACT FROM AUTHOR]

The results of experiments with a model of an optically pumped rare-gas laser are presented. Laser generation was produced simultaneously at three wavelengths (912.3, 893.1, and 877.7 nm) using a gas mixture consisting of 98% He (buffer gas), 1.5% Ar, and 0.5% Kr. Dependence of generation power and of the ratio of the intensities of individual lines in total generation on consumption of the gas mixture, on cuvette pressure, and on the discharge pulse repetition rate has been studied experimentally. The maximum laser power (the sum of all the wavelengths) was ~8 mW. [ABSTRACT FROM AUTHOR]

Molecular beam mass spectrometry (MBMS) has been adapted at the gas dynamic stand LEMPUS-2 to study the free molecular beam particle-scattering process on particles of the background gas. The verification of the used technique in noncondensing flows was carried out, and the results of measuring the effective scattering cross sections of argon atoms and nitrogen molecules were compared with the known literature data. The process of atoms and small argon clusters (oligomers) scattering on carbon dioxide particles located in the background space at different average sizes of clusters 〈N〉 formed in the flow is investigated. When 〈N〉 ≈ 48, the obtained scattering cross-sections for argon atoms, dimers, and trimers is 39, 17, and 6 Å2, respectively. With an increase in the average cluster size in the flow, the effective scattering cross-section of argon atoms decreases. The paper discusses the causes of the detected effect as well as the features of MBMS use for the study of supersonic clustered jets. [ABSTRACT FROM AUTHOR]