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The time-dependent rotational and vibrational temperatures were measured to study the shock-heated thermal nonequilibrium behaviors of CO with Ar, He, and H2 as collision partners. Three interference-free transition lines in the fundamental vibrational band of CO were applied to the fast, in situ, and state-specific measurements. Vibrational relaxation times of CO were summarized over a temperature range of 1110–2820 K behind reflected shocks. The measured rotational temperature instantaneously reached an equilibrium state behind shock waves. The measured vibrational temperature experienced a relaxation process before reaching the equilibrium state. The measured vibrational temperature time histories were compared with predictions based on the Landau–Teller model and the state-to-state approach. The state-to-state approach treats the vibrational energy levels of CO as pseudo-species and accurately describes the detailed thermal nonequilibrium processes behind shock waves. The datasets of state-specific inelastic rate coefficients of CO–Ar, CO–He, CO–CO, and CO–H2 collisions were calculated in this study using the mixed quantum-classical method and the semiclassical forced harmonic oscillator model. The predictions based on the state-to-state approach agreed well with the measured data and nonequilibrium (non-Boltzmann) vibrational distributions were found in the post-shock regions, while the Landau–Teller model predicted slower vibrational temperature time histories than the measured data. Modifications were applied to the Millikan–White vibrational relaxation data of the CO–Ar and CO–H2 systems to improve the performance of the Landau–Teller model. In addition, the thermal nonequilibrium processes behind incident shocks, the acceleration effects of H2O on the relaxation process of CO, and the characterization of vibrational temperature were highlighted. [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 time-dependent rotational and vibrational temperatures were measured to study the shock-heated thermal nonequilibrium behaviors of CO with Ar, He, and H2 as collision partners. Three interference-free transition lines in the fundamental vibrational band of CO were applied to the fast, in situ, and state-specific measurements. Vibrational relaxation times of CO were summarized over a temperature range of 1110–2820 K behind reflected shocks. The measured rotational temperature instantaneously reached an equilibrium state behind shock waves. The measured vibrational temperature experienced a relaxation process before reaching the equilibrium state. The measured vibrational temperature time histories were compared with predictions based on the Landau–Teller model and the state-to-state approach. The state-to-state approach treats the vibrational energy levels of CO as pseudo-species and accurately describes the detailed thermal nonequilibrium processes behind shock waves. The datasets of state-specific inelastic rate coefficients of CO–Ar, CO–He, CO–CO, and CO–H2 collisions were calculated in this study using the mixed quantum-classical method and the semiclassical forced harmonic oscillator model. The predictions based on the state-to-state approach agreed well with the measured data and nonequilibrium (non-Boltzmann) vibrational distributions were found in the post-shock regions, while the Landau–Teller model predicted slower vibrational temperature time histories than the measured data. Modifications were applied to the Millikan–White vibrational relaxation data of the CO–Ar and CO–H2 systems to improve the performance of the Landau–Teller model. In addition, the thermal nonequilibrium processes behind incident shocks, the acceleration effects of H2O on the relaxation process of CO, and the characterization of vibrational temperature were highlighted. [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]

The performance of plasma sprayed thermal barrier coatings (TBCs) is strongly dependent on the quality of the feedstock powders, which usually are fabricated by conventional spray drying and multi-step sintering methods. In this work, a novel supersonic plasma spheroidization technology was employed to fabricate the spherical nanocrystalline Sc 2 O 3 -Y 2 O 3 co-stabilized ZrO 2 (ScYSZ) powder. The deformation process from the irregular powder to the spherical one was stimulated by the COMSOL phase field simulation. The results suggested that the original irregular pyrolysis products of ScYSZ precursors were aggregated into spherical powders by plasma spheroidization technology. The COMSOL simulations verified that the powder changed from irregular particles to spherical ones. The spheroidized ScYSZ particles exclusively consisted of non-transformed t' -ZrO 2 phase and showed good fluidity, smooth surface and high apparent density, which were expected to have a broader application prospect in the field of TBCs and other ceramic coatings. [ABSTRACT FROM AUTHOR]

This study presents the comparative analysis of untreated, optimized non-thermal plasma (NTP)–treated (38 kV/631 s), extreme NTP–treated (45 kV/900 s), and thermally treated (95 ℃/12 min) pineapple juice (PJ) on enzyme activity, microbial count, protein structure, particle size, bioactive substances and, sensory, rheological, and biochemical attributes. The PJ treated with optimized NTP demonstrated merits over extreme NTP–treated and thermally treated in terms of the retention of bromelain, bioactive components, and biochemical attributes. Moreover, the fuzzy logic evaluation showed that optimized NTP–treated juice had superior sensory characteristics than extremely NTP– and thermally treated juice. The NTP approach, like thermal treatment (95 ℃/12 min), extends shelf life by assuring microbiological safety (<1 log10 cfu/mL) and enzyme inactivation (>90%). However, the thermal treatment resulted in loss of bioactive, sensory, and biochemical attributes. Particle size distribution indicates that NTP significantly (p < 0.05) reduced the sauter mean and volume mean diameter from 1617 to 894 nm and 1688 to 917 nm, respectively, which stabilized juice after treatment. NTP treatment substantially reduced the consistency from 1.22 to 0.31 mPa.sn and showed a pseudo-plastic behavior of juice. These results collectively imply that NTP has a tremendous ability to maintain bioactive compounds, and sensory and physicochemical attributes, as well as extend the shelf life of PJ. [ABSTRACT FROM AUTHOR]

A study of cosmic ray modified shock structures is presented for a system of four fluids consisting upon cosmic rays, thermal plasmas, forward and backward propagating self-excited Alfvén waves. A fluid model is employed to study the energy exchange mechanisms for the shock formation where cosmic rays, forward and backward propagating Alfvén waves are taken massless fluids in the comparison of thermal plasmas. This work may help to understand theoretical and observational perspective of the processes involved in supernova environment. [ABSTRACT FROM AUTHOR]

Standard magnetic reconnection couples with both ions and electrons on different scales. Recently, a new type of magnetic reconnection, electron‐only reconnection without the coupling of ions, has been observed in various plasma environments. Standard reconnection typically has a reconnection outflow velocity of about one Alfvén speed. According to the scaling analysis, the electron outflow velocity is expected to be about one electron Alfvén speed in electron‐only reconnection. However, observations and simulations both find that the electron outflows are much slower than the electron Alfvén speed. In this letter, by performing two‐dimensional particle‐in‐cell simulations, we show that this is because ions play a role in electron‐only reconnection. The ions move slower than the electrons in the outflow direction, and such charge separation forms an in‐plane Hall electric field, which prevents the electrons from being accelerated to the electron Alfvén speed in electron‐only reconnection. Plain Language Summary: Magnetic reconnection is a fundamental plasma process during which magnetic field line topologies change and magnetic energy transfers to plasma kinetic and thermal energy. In standard collisionless magnetic reconnection, ions and electrons are both heated and accelerated to form high‐speed outflow. Theoretical analyses have been performed to successfully explain the fast outflow speed in standard magnetic reconnection. Recently, a new type of magnetic reconnection, electron‐only reconnection (in which there is no obvious ion heating and acceleration) has been reported to occur in various plasma environments. However, the same scaling analyses performed in electron‐only reconnection overestimate the outflow speed in the electron‐only reconnection by a factor of ∼10. Here, by performing two‐dimensional (2‐D) particle‐in‐cell (PIC) simulations, we show that the overestimation is due to the neglect of the role of ions. Because of the in‐plane Hall electric field caused by charge separation, electron outflow in electron‐only reconnection cannot be accelerated to the expected value. Key Points: Electrons are not accelerated to electron Alfvén speed in electron‐only magnetic reconnectionDeceleration of electron outflow caused by in‐plane Hall electric field should not be ignored [ABSTRACT FROM AUTHOR]

This paper focuses on the use of catalysts generated from metal–organic frameworks (MOFs) for the degradation of toluene in a linked non-thermal plasma/photocatalytic process. The porous tri-metal oxide catalyst (MCNOx) was derived from the metal organic framework (MOF-74) via an in situ pyrolysis strategy utilizing Mn-doped CoNi-MOF-74 as the precursor. The resulting MCNOx material exhibits a unique series of surface defects, which significantly enhances its catalytic activity. We found that MCNOx materials, due to their high specific surface area, regular porous structure, and excellent reducibility, can synergize well with NTP in the complete decomposition of toluene, which makes the NTP coupled catalytic system have better catalytic activity and CO2 selectivity. The toluene conversion temperature of T90 in the NTP synergistic thermocatalytic system was 250 °C for the 5MCNOx catalyst, which was also much higher than that of 1MCNOx (256 °C), 10MCNOx (258 °C), CNOx (270 °C), and 5MCNOx catalyst in the monocatalytic system (270 °C). In addition, the catalytic stability of MOF-derived MCNOx oxides and the influence of water vapor on catalytic activity were investigated, confirming their excellent catalytic performance. Finally, the importance of Mn doping in improving toluene oxidation activity on MOF-74 derived CNOx has been demonstrated, providing a viable strategy for developing a toluene oxidation catalyst. [ABSTRACT FROM AUTHOR]

The development of reduced models provide efficient methods that can be used to perform short term experimental data analysis or narrow down the parametric range of more sophisticated numerical approaches. Reduced models are derived by simplifying the physics description with the goal of retaining only the essential ingredients required to reproduce the phenomena under study. This is the role of the gyro-fluid code FAR3d, dedicated to analyze the linear and nonlinear stability of Alfvén Eigenmodes (AE), Energetic Particle Modes (EPM) and magnetic-hydrodynamic modes as pressure gradient driven mode (PGDM) and current driven modes (CDM) in nuclear fusion devices. Such analysis is valuable for improving the plasma heating efficiency and confinement; this can enhance the overall device performance. The present review is dedicated to a description of the most important contributions of the FAR3d code in the field of energetic particles (EP) and AE/EPM stability. FAR3d is used to model and characterize the AE/EPM activity measured in fusion devices as LHD, JET, DIII-D, EAST, TJ-II and Heliotron J. In addition, the computational efficiency of FAR3d facilitates performing massive parametric studies leading to the identification of optimization trends with respect to the AE/EPM stability. This can aid in identifying operational regimes where AE/EPM activity is avoided or minimized. This technique is applied to the analysis of optimized configurations with respect to the thermal plasma parameters, magnetic field configuration, external actuators and the effect of multiple EP populations. In addition, the AE/EPM saturation phase is analyzed, taking into account both steady-state phases and bursting activity observed in LHD and DIII-D devices. The nonlinear calculations provide: the induced EP transport, the generation of zonal structures as well as the energy transfer towards the thermal plasma and between different toroidal/helical families. Finally, FAR3d is used to forecast the AE/EPM stability in operational scenarios of future devices as ITER, CFETR, JT60SA and CFQS as well as possible approaches to optimization with respect to variations in the most important plasma parameters. [ABSTRACT FROM AUTHOR]

ABSTRACT The present work deals with the Argon (Ar) Thermal plasma‐induced surface modification of Cu and its correlation with the electrical and field emission (FE) properties. Polycrystalline Cu targets were treated with Ar thermal plasma under atmospheric pressure at different treatment times ranging from 5 min to 30 min. XRD patterns revealed the absence of new phase in treated samples. However, significant variation in peak intensities and shifting is observed, which is explained on the basis of thermal plasma ions induced defect generation and annihilation processes. The electrical conductivity of processed Cu targets measured by four‐probe method ranges from 1.9 MS/m to 70 MS/m and is well correlated with the crystallite size variation. Surface modification induced work function alternations investigated by employing Scanning Kelvin Probe (SKP) technique are in the range of 4.69 eV 4.97 eV. The irradiated morphology explored by optical and scanning electron microscopy analyses revealed the formation of localized melt pools, grains, hillocks, spheroids, and sputtered patches, which are explainable on the basis of Coulomb's explosion, thermal spike model, plasma‐induced sputtering, and re‐deposition. FE properties of thermal plasma‐treated Cu are measured in diode configuration by measuring I‐V characteristics of target under ultra‐high vacuum condition. The improved FE parameters such as turn‐on field (Eo), field enhancement factor (β), and maximum current density (Jmax) come out to be in the range of 3–7.5 V/μm, 1715–3223, and 284–872 nA/cm2, respectively and their correlation with plasma‐induced surface structural, morphological and work function modifications is discussed. [ABSTRACT FROM AUTHOR]

Low-cost micromanufacturing technique for forming copper foils into desired micro-parts plays an important role in facilitating the widespread application of copper foil. Here, the pulsed arc plasma generated by the pulsed voltage was used as a heat source to achieve thermal stress–induced bending of copper foil in an electrical discharge machining (EDM) machine. Metallic foil with a thickness of 0.1 mm and a cylindrical rod with scanning motion were used for the first time as tool electrodes in the EDM bending of workpieces. The effect of various processing parameters, such as polarity, machining time, discharge current, duty factor, and discharge frequency, on the bending angle was investigated by optical microscopy. The main factors affecting the bending angle and their working mechanisms were analyzed in depth. Experimental results showed that the bending angle of the copper foil increases with the increase of the discharge energy, which was mainly attributed to the increasing thermal gradient along the thickness direction of the copper foil. When the copper foil was used as the anode, the carbon deposition phenomenon in the copper foil effectively reduced the material removal caused by the pulsed arc plasma, which contributes to the surface integrity and performance of the copper foil. Furthermore, several typical bend-formed parts, including curved, sawtooth, and S-shapes, were formed using pulsed arc plasma. This work proves that pulsed arc plasma is a reliable and cost-effective heat source for achieving thermal stress–induced bending of copper foil. [ABSTRACT FROM AUTHOR]

Plasma-based methods present a highly efficient approach for reclaiming valuable metals and nanoparticles from discarded metal scraps and minerals. In this research, we employed the thermal plasma arc discharge (TPAD) method to synthesize mixed-phase spinal-type magnesium aluminate and magnesium oxide (MgAl 2 O 4 /MgO) nanocomposites ranging in size from 10 to 120 nm, using discarded MgAl alloy waste scraps as the primary material. By employing comprehensive characterization techniques such as powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and energy dispersive X-ray analysis (EDS), we successfully confirmed the formation of highly crystalline MgAl 2 O 4 /MgO nanocomposites, showcasing a nearly spherical morphology. The surface area of the prepared nanocomposites was investigated using Brunauer-Emmett-Teller (BET) analysis; the values are 51.3 m2g-1. The synthesized MgAl 2 O 4 /MgO nanocomposites displayed exceptional photocatalytic activity toward industrial wastewater and commercial dye. Moreover, investigated the storage properties of MgAl 2 O 4 /MgO nanocomposites as an electrode material, revealing a good specific capacitance of 379.2 F/g at a current density of 1 A/g, demonstrating pseudocapacitive behavior. These results offer valuable insights into sustainable waste utilization and the development of high-performance nanomaterials for practical applications in various fields. [ABSTRACT FROM AUTHOR]

In this study the electron density of an atmospheric plasma generated between a pin electrode and a water surface is measured by determining the Stark broadening of H α and H β emission lines. Comparable values for the electron density are achieved using the H α and H β broadening obtained in separate measurements. During the temporally evolving system, increasing electron densities are measured of 0.5 − 3 ⋅ 10 15 cm−3 during the plasma treatment of 5–10 min. The effect of the water temperature on plasma-water interaction is investigated by heating the water to ≈ 70 ∘ C prior to the measurements. This resulted in higher gas temperatures during the discharge up to 2500 K and 4000 K for positively and negatively pulsed discharge, respectively. Furthermore, an earlier increase of electron density and conductivity of the water is measured for the preheated experiments. The humidity of the gas is likely to be an important parameter causing the observed results. [ABSTRACT FROM AUTHOR]

Low-temperature plasma ablation has been recently used for minimally invasive surgeries. However, more research is still needed on its generation process during tissue ablation and the underlying mechanism of tissue thermal damage. In this paper, high-speed camera footage, voltage–current signal collection, temperature analysis, and histological analysis were used to investigate the dynamic process of plasma tissue ablation and its thermal effect of dual-needle electrodes immersed in normal saline, which were driven by a high-frequency DC power supply with an output voltage ranging from 220 V to 320 V and a squire wave of 100 kHz. Microbubbles occurred around the ground electrode and merged to form a vapor layer that could completely cover the ground electrode. Plasma capable of ablating tissue would occur in the vapor layer between the ground electrode and tissue. The effect of electrical parameters on plasma generation and its thermal effect are analyzed by statistical results. The experimental results indicated that the voltage applied to the electrodes significantly influenced both the generation and stability of plasma, as well as the heat generation and tissue damage around the electrodes. Furthermore, under the same voltage, the existence of biological tissue promotes the formation of a vapor layer around the electrode, thereby facilitating the generation and stability of plasma. Notably, the temperature rise around the ground electrode is much higher than that around the powered electrode. These results have direct application to the design of plasma tissue ablation systems, which could achieve tissue ablation effects with minimal thermal damage. [ABSTRACT FROM AUTHOR]

In this study, the origins of efficiency gains in Cu(In,Ga)Se2 (CIGS) solar cells are investigated by introducing an Al2O3 passivation layer in terms of the oxidation condition of Mo back contact, alkali‐metal diffusion, minority carrier lifetimes (τ), and charge conditions. The study reveals that introduction of an Al2O3 back‐contact passivation layer into solar cells yields multiple impacts. Al2O3 deposition enhances the oxidation of the Mo back contacts, increasing Na solubility in Mo and Na diffusion from Mo into the CIGS layer, thereby modifying the metastable properties of CIGS. The charge condition at the CIGS/Al2O3 interface is not fixed negative charge but variable, dependent on whether electrons or holes are supplied. During solar cell operation, the interfacial charge condition is expected to be neutral or positive for Al2O3 grown using plasma or thermal atomic layer deposition techniques, respectively. Moreover, the mechanical peeling off of CIGS from Mo back contact enhanced τ in a similar way as with the insertion of Al2O3. Based on this study, the enhancement of alkali metal supply and the removal of direct contact of CIGS to the metal contact (Mo) can play crucial roles in improving the performance of CIGS solar cell. [ABSTRACT FROM AUTHOR]

This paper examines the holographic computation of bulk and shear vis- cosity ratios in strongly coupled thermal plasmas using the AdS/BCFT correspon- dence within Horndeski gravity. We demonstrate that this framework leads to non-zero viscosity-to-entropy ratios (ζ/S and η/S) at low temperatures, indicating a break in conformal symmetry. At high temperatures, these ratios approach zero, recovering the expected conformal behavior of quark-gluon plasma. Our findings provide new insights into the hydrodynamic properties of strongly coupled plasmas and offer a more nuanced understanding of QCD-like theories in holographic models. [ABSTRACT FROM AUTHOR]

Non-thermal plasma (NTP) catalysis is considered one of the most promising technologies to address a wide range of energy and environmental needs, such as carbon dioxide (CO2) conversion, NH3 synthesis, and volatile organic compounds (VOCs) removal. A systematic approach to optimizing NTP systems benefits from understanding VOCs' fundamental NTP destruction behavior and analyzing the correlations between molecular structures and conversion and selectivity. Herein, the mechanical performance of the toluene destruction in NTP is examined and compared with benzene bearing a similar molecular structure. Different experimental and theoretical techniques are applied, including synchrotron vacuum ultraviolet photoionization mass spectrometry(SVUV-PIMS), thermochemistry, and quantum chemistry. Comparatively, toluene is more readily destroyed under the same NTP conditions than benzene. More intriguingly, the distribution of the decomposition species is significantly different. The theoretical calculations reveal that the abundant methyl radicals generated in toluene decomposition mainly lead to the various species distribution. These radicals promote some reactions, such as the decomposition of obenzoquinone, one of the key intermediates, thus leading to new reaction pathways and products different from benzene. Finally, the critical mechanistic steps of toluene decomposition under the present non-thermal plasma conditions are established, which include the interactions between toluene and electrons or reactive radicals, the cleavage of the aromatic ring, and the various reaction pathways involving of methyl radicals. This study presents an effective approach to elucidate the distinct fundamental reaction mechanisms arising from subtle structural differences, offering new insights into the underlying plasma chemistry crucial for advancing various promising environmental and energy applications of non-thermal plasma systems. [ABSTRACT FROM AUTHOR]

The thermal effect of a single-dielectric-barrier-discharge plasma actuator under steady actuation is numerically investigated. A new actuator model is proposed and validated using experimental data. A discrete Galerkin method based on high-order flux reconstruction schemes is employed to solve the flow governing equations and the actuator model equations on unstructured quadrilateral grids. By comparing the induced heated and cold flow fields of the actuator with and without a plasma thermal source, its thermal effect is revealed. The actuator generates a thermal wall jet with rich vorticity, forming a monopolar starting vortex with a high-temperature and low-density core. Over time, the starting vortex becomes unstable and transforms into a dipole. Actuator heating enhances jet velocity and width, as well as vortex stability, while slowing down vorticity generation. The relative change in density and temperature fields due to actuator heating is four orders of magnitude greater than that without actuator heating. Additionally, the actuator heating causes the background thermodynamic fields to increase approximately linearly with time. Two stages in the actuator's thermal effect are distinguished due to time accumulation. Initially, the actuator heating minimally affects the monopolar starting vortex motion, and the temperature and density fields are treated as passive variables driven by the velocity field. During this stage, the momentum and thermal effects of the actuator can be studied separately. However, after the starting vortex becomes unstable, the actuator heating significantly impacts its motion and morphology, and these two effects are coupled with each other. [ABSTRACT FROM AUTHOR]

Thermal plasma melting was applied to mixtures of MgO, Al 2 O 3 and Tb 4 O 7 to synthesize the MgAl 2 O 4 :Tb3+ (0.1–10 % wt. Tb 4 O 7) luminescent ceramics series. Coarse-grained spinel materials (0.1–1 mm) with preferred crystal orientation were obtained. Structural, morphological (XRD and SEM) and spectroscopic (cathodoluminescence and Raman spectroscopy) analysis were used to investigate the influence of Tb 4 O 7 content on ceramics phase composition, cell parameter of MgAl 2 O 4 :Tb3+, the inversion degree, and luminescent properties. It was found that the thermal plasma synthesized spinel ceramics exhibit a non-controlled inversion degree. The formation of TbAlO 3 as a by-product was observed in materials containing more than 1 wt% of Tb 4 O 7. It was demonstrated that the thermal plasma melting method could be potentially applied for fast preparation of MgAl 2 O 4 :Tb3+ luminescent ceramics. [ABSTRACT FROM AUTHOR]

In Magnetic Resonance Imaging (MRI), manganese oxides are predominantly used as contrast agents (CAs) to enhance contrast of T 1 –weighted acquisitions. In this work, Mn 3 O 4 nanomaterials were synthesized by high temperature thermal plasma route and thoroughly characterized by structural, microscopic and biocompatibility investigations. The nanoparticles so obtained display both T 1 and T 2 MRI contrast properties. This was attributed to the fact that the nanomaterials synthesized by thermal plasma route possess higher saturation magnetization than those synthesized by various chemical methods. The presence of oxygen vacancies and relatively large size of the synthesized nanoparticles can also be regarded as other two reasons behind attainment of T 1 -T 2 dual contrast. Thermal plasma synthesized nanomaterials have never been earlier demonstrated as MRI CAs. Moreover, this is the first report presenting detailed characterization of the thermal plasma synthesized Mn 3 O 4. The microstructure of the synthesized Mn 3 O 4 nanoparticles was observed to be spherical in shape. The biocompatibility of the developed nanosystem was established by cell viability analysis. Finally, the efficiency of the agent for T 1 –T 2 contrast enhancement was confirmed through MRI experiments. This work lays the foundation of research on a new class of MRI CAs synthesized by thermal plasma. [ABSTRACT FROM AUTHOR]

Additive manufacturing is a promising and actively developing method for the synthesis of metal products. The development of techniques for the production of spherical powder particles with specified properties from metals and alloys represents a significant challenge in the field of additive manufacturing. A new method for the production of titanium powders with spherical particles has been proposed, including the method of hydrogenation and dehydrogenation with subsequent spheroidization in thermal plasma. Titanium sponge, used as a feedstock, was saturated with hydrogen using the energy-efficient self-propagating high-temperature synthesis (SHS) method. The resulting hydride was then mechanically ground and then dehydrogenated by thermal decomposition in a vacuum furnace. The resulting precursor was subjected to plasma treatment, which resulted in a product (titanium powder) with a high degree of spheroidization. The physical, chemical, and technological parameters of the titanium powders were investigated. It was found that the final product, spherical titanium powder, has the necessary properties for use in additive manufacturing technologies. [ABSTRACT FROM AUTHOR]

The W/Cu binary system is characterized by its mutual insolubility and excellent wettability, making W/Cu composite materials ideal for managing thermal and electrical properties in electronic components. To optimize material properties, control over the microstructure is crucial, and nanocomposites with uniform dispersion offer significant advantages. In this study, W/Cu composite nanoparticles were synthesized by feeding a blended feedstock of tungsten trioxide (WO3) micro-powder and cupric oxide (CuO) micro-powder into a reactive radio frequency (RF) argon–hydrogen thermal plasma system. Cu-coated W nanocomposite particles were obtained through the vaporization, reduction, and condensation processes. The resulting nanocomposite particles were composed of body-centered cubic (BCC) α-W, A15 β-W, and face-centered cubic (FCC) Cu phases, with a chemical composition closely matching theoretical calculations. The phase evolution and morphological changes of the synthesized particles were analyzed as a function of heat treatment temperatures up to 1000 °C in a reducing atmosphere. Up to 600 °C, the phase composition and morphology remained stable. At 800 °C, localized diffusion and coalescence of Cu led to the formation of particulate Cu, and a significant phase transformation from metastable β-W to α-W was observed. Additionally, extensive Cu segregation due to long-range diffusion resulted in distinct Cu-rich and Cu-depleted regions. In these regions, notable sintering of W particles and the complete disappearance of β-W occurred. The results showed that the temperature-dependent redistribution of Cu plays a crucial role in the phase transformation of W and the morphology of W/Cu composite particles. [ABSTRACT FROM AUTHOR]

The process of obtaining powders from the 5–50 μm fraction of a W-Ni-Fe system consisting of particles with predominantly spherical shapes was investigated. Experimental studies on the plasma–chemical synthesis of a nanopowder composed of WNiFe-90 were carried out in a plasma reactor with a confined jet flow. A mixture of tungsten trioxide, nickel oxide, and iron oxide powders interacted with a flow of hydrogen-containing plasma generated in an electric-arc plasma torch. The parameters of the spray-drying process and the composition of a suspension consisting of WNiFe-90 nanoparticles were determined, which provided mechanically strong nanopowder microgranules with a rounded shape and a homogeneous internal structure that contained no cavities. The yield of the granule fraction under 50 μm was 60%. The influence of the process parameters of the plasma treatment of the nanopowder microgranules in the thermal plasma flow on the degree of spheroidization and the microstructure of the obtained particles, seen as their bulk density and fluidity, was established. It was shown that the plasma spheroidization of the microgranules of the W-Ni-Fe system promoted the formation of a submicron internal structure in the obtained spherical particles, which were characterized by an average tungsten grain size of 0.7 μm. [ABSTRACT FROM AUTHOR]

Yb-doped Y2O3 stabilized ZrO2 (YbYSZ) coatings, developed through solution precursor plasma spraying (SPPS), are engineered to resist calcium–magnesium–alumino–silicate (CMAS) infiltration by leveraging their unique micro-nano structures. This provides superior anti-wetting properties, crucial for preventing CMAS penetration at high temperatures. The investigation focused on the structural and compositional changes in YbYSZ-SPPS coatings subjected to prolonged thermal exposure at 1300 °C. Results indicate that while the coatings undergo significant sintering, leading to densification and microstructural evolution, the elemental composition and phase stability remain largely intact after up to 8 h of heat treatment. Despite some reduction in CMAS resistance, the coatings maintained their overall protective performance, demonstrating the potential of SPPS coatings for long-term use in high-temperature environments where CMAS infiltration is a concern. These findings contribute to the development of more durable TBCs for advanced thermal protection applications. [ABSTRACT FROM AUTHOR]

Thermal plasma is a versatile technology that can be used to treat various types of wastes, including vegetal and mineral oils, solvents, plastics, paper and cardboard, glasses, bricks and rocks, metals, clothes, and mixtures of these materials. In this study, we utilized a commercial plasma cutter as a thermal plasma source to decrease the volume of a simulated low-level radioactive mixed solid waste. The simulated waste included papers, plastics, clothes, gloves, metals, and stable Co, Cs, Sr, and Ce additives as surrogates of 60Co, 137Cs, 90Sr, and 144Ce, respectively, the latter being typical contaminants in nuclear LLW. As a result of the process, two products were obtained: a solid phase, on which we focused this work, and a gaseous phase. To retain as many as surrogates as possible in the solid final phase, crushed glass from broken bottles was included as a vitrification additive to the original waste. After undergoing heat treatment, a dense vitreous slag was produced along with ashes. The process resulted in a volume reduction of 70%, indicating the successful gasification of organic excess materials. The surrogate elements were retained in the process and were found in the ashes composition: Co (3.4% w/w), Cs (37.7% w/w), and Ce (0.6% w/w) and in the glass matrix composition of Co, Cs, Sr and Ce: 72.4 ± 14.7, 32 ± 18.2, 125.3 ± 31.6, 80 ± 13.1% w/w, respectively. For the actual experimental conditions, retention efficiencies were estimated for cobalt (Co) at 72.4 ± 14.7%, cerium (Ce) at 80 ± 13.1%, strontium (Sr) at 125.3 ± 31.6%, and notably cesium (Cs) at 32 ± 18.2%. [ABSTRACT FROM AUTHOR]

Non-thermal plasma as an emergent technology has received considerable attention for its wide range of applications in agriculture, material synthesis, and the biomedical field due to its low cost and portability. It has promising antimicrobial properties, making it a powerful tool for bacterial decontamination. However, traditional techniques for producing non-thermal plasma frequently rely on radiofrequency (RF) devices, despite their effectiveness, are intricate and expensive. This study focuses on generating Ar-O2 capacitively coupled plasma under vacuum conditions, utilizing a low-frequency alternating current (AC) power supply, to evaluate the system's antimicrobial efficacy. A single Langmuir probe diagnostic was used to assess the key plasma parameters such as electron density (ne), electron temperature (Te), and electron energy distribution function (EEDF). Experimental results showed that ne increases (7 × 1015 m−3 to 1.5 × 1016 m−3) with a rise in pressure and AC power. Similarly, the EEDF modified into a bi-Maxwellian distribution with an increase in AC power, showing a higher population of low-energy electrons at higher power. Finally, the generated plasma was tested for antimicrobial treatment of Xanthomonas campestris pv. Vesicatoria. It is noted that the plasma generated by the AC power supply, at a pressure of 0.5 mbar and power of 400 W for 180 s, has 75% killing efficiency. This promising result highlights the capability of the suggested approach, which may be a budget-friendly and effective technique for eliminating microbes with promising applications in agriculture, biomedicine, and food processing. [ABSTRACT FROM AUTHOR]

The main goal was to investigate the ability of a non-thermal plasma reactor with gliding arc discharge to remove diesel exhaust particulates (DEPs). A conventional knife-shaped LTP GA (low-temperature plasma gliding arc) reactor was utilized. The following three cases were studied: 140 L/min, 70 L/min, and 14 L/min of air drawn through the reactor, and diesel exhaust fumes were sampled continuously. They were assayed in terms of concentration and number particle size distribution. The higher the residence times, the higher the energy input that may be utilized for DEPs' removal. The reactor performance definitely lowered the concentration of DEPs (250–580 nm) and altered their number size distribution. There was no effect on the number concentration, nor the particle size distribution, of DEPs of 10–250 nm in size. Regarding the effectiveness of DEPs' removal, decreasing the flow rate from 140 L/min to 70 L/min somehow altered the values. Achieving the airflow of 14 L/min led to a substantial improvement (even to a fourfold increase for 300–480 nm particles). Non-thermal plasma reactors with gliding arc discharge may be successfully adapted to the process of DEP treatment. Their performance may be optimized by adjusting the airflow at the inlet of the reactor to guarantee the longest aerosol residence times and the highest removal efficiency. [ABSTRACT FROM AUTHOR]

This study investigates the paracetamol removal efficiency by multi-tip pulsed corona discharges, highlighting the conditions avoiding mutual effects between two consecutive streamer branching discharges generated by each tip. The results show that the production of reactive oxygen and nitrogen species (RONS) in the liquid phase and the efficiency of paracetamol removal are influenced by the distance between two contiguous tips due to the mutual effects for small inter-tip distances between 4 mm and 8 mm in the case of a fixed inter-electrode distance of 5 mm (i.e. distance between the tip summit and the water surface). Beyond an inter-tip distance of 12 mm (over twice the gap distance), the mutual effects of branching discharges were no longer observed since the field lines did not overlap, making the production and absorption of liquid-phase species more efficient. Furthermore, RONS production was almost linear when moving from one to four tip electrodes: [H2O2]1tip: 0.52 mg l–1 versus [H2O2]4tips: 1.99 mg l–1, a ratio of 3.82. Optimum values were reached for an inter-tip distance of 16 mm. In this case, the enhancement factor in this reactor configuration is the surface integration between the plasma and the liquid surface to be treated. Furthermore, the results show a quasi-exponential increase in the percentage of paracetamol degradation as a function of the number of electrodes, from 4% with a mono-tip configuration to over 78% for a treatment with a four tip one. [ABSTRACT FROM AUTHOR]

Multilayer plastic (MP) commonly used in food and beverage packaging is difficult to recycle due to its layered structure, resulting in its accumulation over time; the consequent environmental harm is further exacerbated by its short lifespan. This study investigates recycled low-value MP as a modifier for polymer-modified bitumen (PMB). However, the difference in polarity between MP and PMB mixtures is a challenge, resulting in their poor compatibility and reduced mechanical properties. To overcome this, low-value MP was treated with atmospheric cold plasma and thermal oxidation to enhance its compatibility with PMB. The results indicate that plasma and thermal treatments increase the hydrophilicity of low-value MP through the formation of low-molecular-weight oxidized molecules containing hydrophilic hydroxyl (-OH) and carbonyl (C = O) groups that act as an intermediary boundary layer between the low-value MP and asphaltene-rich bitumen. Further, the optimal oxidation conditions for MP are revealed as 60 s of plasma treatment followed by heating at 150 °C for 60 min. Mixtures of PMB and optimally oxidized MP have optimal compositions of 1 wt.%, with ductility and penetration values of 87.7 cm and 57.4 mm, respectively. [ABSTRACT FROM AUTHOR]

In this study, we explore the potential of using laser-induced photo-fragmentation of O3 by UV radiation as a quantitative diagnostic tool in non-thermal O2-mixed plasmas. We analyze the optical processes of O3 using a comprehensive kinetic model with a 226 nm laser, which is typically used in the two-photon absorption laser-induced fluorescence (TALIF) measurement of O atoms. Our model demonstrates that the fluorescence intensity from atomic O fragments produced by the same laser is directly proportional to the population of precursor O3. This makes various diagnostic purposes achievable through the proposed O3 full photo-fragmentation (FPF) TALIF spectroscopy, including calibration of TALIF signals of O atoms and quantification of both O and O3 in O2-mixed plasmas. We present detailed theoretical principles, technical requirements, and successful examples of implementation for different diagnostic aims using the proposed O3 FPF-TALIF spectroscopy. However, we also specify the limitations of the developed diagnostic methods, particularly under low E/N conditions (<30 Td), where other interferential species such as the vibrationally excited ground-state O 2 ( X 3 Σ g − , v ≠ 0) are abundantly produced. [ABSTRACT FROM AUTHOR]

The thermal decomposition and ignition of high-performance high explosives occur via a mechanism where the solid phase sublimes and the parent molecules decompose rapidly in the gas phase to form unstable and charged intermediates. These intermediates continue to react and form the final products to release energy and do work. We have observed that the presence of electromagnetic energy significantly reduces the ignition temperature of a common high explosive, and data suggest that this occurs via electromagnetic interactions with the charged gas-phase intermediates. Here, we modified the thermal decomposition kinetic expressions for octogen (High Melt eXplosive, HMX) to couple the effects of an incident microwave (MW) field. This modified kinetic model is used to investigate our previous experimental work which showed that the surface temperature at ignition of HMX powder is reduced by the MW field. The Fridman–Macheret α-model is a common approach in plasma chemistry and was incorporated into the Henson/Smilowitz HMX kinetics; this effectively reduces the activation energy (Ea) by vibronically excited charged reactive intermediates. A modified kinetic model was implemented into the COMSOL Multiphysics Software. The thermal time to ignition was validated; as a result, plasma formation reduced the surface temperature by ∼23 °C compared to thermal ignition. With a validated kinetic model that can simulate both pure thermal ignition and mixed thermal/plasma ignition, we are able to simulate our previous experimental work showing that plasma ignition reduces the surface temperature at ignition compared to thermal initiation. [ABSTRACT FROM AUTHOR]

The European Green Deal has set a target for Europe to achieve net-zero greenhouse gas emissions by 2050, necessitating a transition to more sustainable energy sources. Hydrogen gas (H 2) has emerged as a promising solution, with methane pyrolysis presenting a viable method for its production. This study explores the optimization of methane plasma pyrolysis for hydrogen and high-quality carbon production. Employing a statistical approach by a design of experiment software, critical process parameters are systematically analyzed to predict their impact within a defined range. Additionally, the paper conducts comprehensive characterization of the solid carbon produced during pyrolysis using imaging, spectroscopic and elemental analysis, and gas sorption analysis methods. The experimental investigation was conducted using a thermal plasma reactor with several settings of influential parameters including methane gas (CH 4) content in the plasma gas, electric current, and arc length. The DC-transferred plasma arc is formed using a variable gas mixture of argon gas (Ar) and CH 4, with a constant flow rate of 5 Nl/min. Thirteen tests were designed, evaluating responses such as power input, process stability, and H 2 yield. The H 2 yield indicates the hydrogen produced from CH 4 , with 100% representing total conversion. While the process exhibited inconstancy, attributed to reactor design constraints, a high H 2 yield of 67%–100% was achieved. The results indicate that a higher CH 4 content in the plasma gas and extended arc lengths disturb the plasma arc, hence reducing the H 2 yield. Increased power input, achieved through higher amperage levels, and a wider reaction zone eased by extending the arc length both led to an improved H 2 yield. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) revealed microstructural differences, with carbon samples from the filter exhibiting finer textures and carbon samples from the reactor larger sizes and dendritic particles. Raman spectroscopy confirmed crystalline graphitic-like structures with low defect concentrations, a finding supported by X-ray diffraction (XRD) analysis. Inductively coupled plasma mass spectroscopy (ICP-MS) analysis confirmed high-purity carbon with slight impurities from initial filter contamination. Brunauer-Emmett-Teller (BET) specific surface area calculations based on gas sorption analysis showed significant variations, with filter-collected samples exhibiting 40–170 m2/g and reactor-collected ones showing 7–30 m2/g. [Display omitted] • This study investigates a unique approach to optimizing the thermal plasma pyrolysis of methane. • A H 2 yield of 67%–100% was achieved utilizing a DC-transferred plasma arc furnace and an Ar and CH 4 mixture plasma gas. • A lower CH 4 content in the plasma gas and an optimized arc length improve the plasma arc and the H 2 yield. • The carbon shows crystalline graphitic-like structures with low defect concentrations. [ABSTRACT FROM AUTHOR]

Background: Thermal ablation is a minimally invasive treatment for non-small cell lung cancer (NSCLC). Aside from causing an immediate direct tumour cell injury, the effects of thermal ablation on the internal microenvironment are unknown. This study aimed to investigate the effects of thermal ablation on the plasma internal environment in patients with NSCLC. Methods: 128 plasma samples were collected from 48 NSCLC (pre [LC] and after thermal ablation [LC-T]) patients and 32 healthy controls (HCs). Olink proteomics and metabolomics were utilized to construct an integrated landscape of the cancer-related immune and inflammatory responses after ablation. Results: Compared with HCs, LC patients exhibited 58 differentially expressed proteins (DEPs) and 479 differentially expressed metabolites (DEMs), which might participate in tumour progression and metastasis. Moreover, 75 DEPs were identified among the HC, LC, and LC-T groups. Forty-eight highly expressed DEPs (eg, programmed death-ligand 1 [PD-L1]) in the LC group were found to be downregulated after thermal ablation. These DEPs had significant impacts on pathways such as angiogenesis, immune checkpoint blockade, and pro-tumour chemotaxis. Metabolites involved in tumour cell survival were associated with these proteins at the expression and functional levels. In contrast, 19 elevated proteins (eg, interleukin [IL]-6) were identified after thermal ablation. These proteins were mainly associated with inflammatory response pathways (NF-κB signalling and tumour necrosis factor signalling) and immune cell activation. Conclusions: Thermal ablation-induced changes in the host plasma microenvironment contribute to anti-tumour immunity in NSCLC, offering new insights into tumour ablation combined with immunotherapy. Trial registration This study was registered on the Chinese Clinical Trial Registry (https://www.chictr.org.cn/index.html). ID: ChiCTR2300076517. Registration Date: 2023-10-11. [ABSTRACT FROM AUTHOR]

Ni60A spraying-cladding coatings were innovatively prepared on the surface of the Q235 steel substrate by plasma spraying-cladding technique. Ni60A powder with a particle size of 30 μm was further selected as the optimum spraying-cladding powder based on preliminary numerical simulation. The spraying-cladding distanceØ was optimized, and the optimum distance was determined as 18 and 16 mm, respectively, for the internal feeding process and external feeding process. The microhardness of the spraying-cladding coating could reach 875.6 HV during the internal feeding process at a spraying-cladding distance of 18 mm, and reach 791.6 HV during the external feeding process at a spraying-cladding distance of 16 mm. Meanwhile, the thermal effect of the plasma spraying-cladding technique on the Q235 steel substrate was less. [ABSTRACT FROM AUTHOR]

This work presents a physics-informed fusion methodology for deformation detection using multi-sensor thermal data. A challenge with additive manufacturing (AM) is that abnormalities commonly occur due to rapid changes in the thermal gradient. Different non-destructive in-situ thermal sensors capture parts of the thermal history but are limited by the visible temperature spectrum and sensor field of view of the fabrication process. Various sensors mitigate problems with the loss of thermal history information; however, it brings forth challenges with integrating different data streams and the need to interpolate the internal thermal history. This study develops a thermal data-informed heat flux methodology that fills the gap in fusing numerical temperature approximation with data-driven knowledge of the surface of additive manufactured components. First, this study fuses infrared (IR) thermal data complexities during the AM process with the Goldak double ellipsoidal heat flux to model the energy input into the component. Second, a thermal physics-informed model input (PIMI) is created with thermal data-informed heat flux to capture internal thermal history. Lastly, a regression convolutional neural network (CNN) captures the relationship between the three-dimensional thermal gradient and the resulting surface deformation. The rapid thermal gradient formation and identification of deformation is a key step toward using thermal history data and machine learning to improve quality control in AM. The proposed surface deformation detection model achieved an mean squared error of 1.14 mm and an R² of 0.89 in the case study when fabricating thin-walled structures. [ABSTRACT FROM AUTHOR]

In this work, the significant lifetime improvement of negative bias thermal instability (NBTI) is demonstrated by the introduction of a thin SiN layer fabricated by plasma enhanced atomic layer deposition (PEALD) in stress memorization technique (SMT). The thin SiN film is deposited before the plasma enhanced chemical vapor deposition (PECVD) of SiN layer with a high tensile stress. It is revealed that the possible H2 escape accompanied with interface de-passivation can be effectively suppressed by this thin PEALD SiN layer, which may further reduce the interface states at Si/gate dielectric interface. Hence, about 500% NBTI lifetime improvement for PMOSFETs is demonstrated without obvious performance degradation for both NMOSFETs and PMOSFETs. [ABSTRACT FROM AUTHOR]

Highly complex high entropy metal oxides (HEOs) have several unique characteristics, such as more active sites and material stability that improve the electrochemical charge storage capacity. In this study, HEOs (Mn, Ni, Mo, Co, Fe) 3 O 4 nanoparticles were synthesized using a thermal plasma route and its electrochemical energy storage performance was studied with two distinct electrolytes such as 1 M KOH and NaOH. The X-ray diffraction analysis revealed the phase pure spinel structured HEOs with crystalline size ranging from 13 to 29 nm. Scanning electron microscopy and electron dispersive X-ray spectroscopy results revealed the quasi-spherical morphology and uniform distribution of constitutional cations in the as-synthesized HEOs. The X-ray photoelectron spectroscopy results identified the oxidation states of cations in spinel HEOs. The charge/discharge studies of as-synthesized HEOs showed a specific capacitance of 215 F g-1 /26.9 mAh g-1 at a current density of 2 A g-1 in 1 M KOH electrolyte which is 156 % greater than 1 M NaOH electrolyte. Furthermore, a high capacitance retention of 91 % was achieved after completing 3000 cycles at 10 A g-1 current density which indicates that the HEOs have excellent charge/discharge reversibility. Electrochemical impedance spectroscopy revealed that the solution and charge transfer resistances of HEOs electrodes were 1.04 and 3.2 Ω, respectively. This novel synthesis strategy attempts to overcome the difficulties experienced by established methods for bulk manufacture of phase pure HEOs since thermal plasma method is a rapid and a single-step approach for the bulk production of nanomaterial. [ABSTRACT FROM AUTHOR]

The transport and kinetic coefficients of copper plasma are studied. The temperature dependences of momentum transfer cross sections, collision frequencies (electron–atom, ion–atom), ionization and recombination rates, thermal diffusion, and thermal and electrical conductivity coefficients are calculated. Formulas are proposed that approximate the results of calculations with high accuracy. The temperature dependence of electrical and thermal conductivity is studied and compared with literature data. The obtained coefficients are necessary for the description of transfer processes in a copper non-equilibrium plasma. [ABSTRACT FROM AUTHOR]

The aim of the present study is to analyze the effect of the neutral beam current drive (NBCD), thermal plasma density, and NBI operational regime on the stability of pressure gradient-driven modes (PGDM) and Alfvén eigenmodes (AE) in LHD inward-shifted configurations. The stabilization of n / m = 1 / 2 PGDM (n toroidal mode and m poloidal mode) is observed in the discharge 167 800 during the co-NBCD phase. The iota profile evolution measured by motional stark effect diagnostic may indicate the iota profile up-shift caused by the co-NBCD can induce a non-resonant transition of the rational surface 1/2 before the mode stabilization. The evolution of the iota profile and continuum gaps in the discharge 167 805 during the ctr-NBCD phase leads to the stabilization of the AE, caused by the narrowing of the continuum gap as the iota profile down-shift. Opposite stability trends are identified for PGDM and AE stability with respect to the thermal plasma density. A larger thermal plasma density (larger thermal β) further enhances PGDM although the continuum gaps are narrower leading to configurations with stable AEs. The linear stability of AEs is analyzed using the gyro-fluid FAR3d code to reproduce the AE stability trends observed in the experiments with respect to the NBCD and thermal plasma density. The analysis of hypothetical scenarios dedicated to study different NBI operational regimes with respect to EP energy, and β and radial density profiles indicate off-axis NBI operation shows a higher EP β threshold to destabilize AEs compared to on-axis configuration. This is explained by the presence of a TAE gap in the inner plasma region, easily destabilized by an on-axis NBI injection. The control of the NBCD and thermal plasma in the discharge 167 800 shows a transitory stabilization of PGDM and AEs, as well as an improved discharge performance identified by an increment of the neutron fluxes. [ABSTRACT FROM AUTHOR]

The nearby ultraluminous infrared galaxy (ULIRG) IRAS F01004−2237 exhibits 100 kpc scale continuum emission at radio wavelengths. The absence of extended X-ray emission in IRAS F01004−2237 has suggested an active galactic nucleus (AGN) origin for the extended radio emission, whose properties and role in merging systems still need to be better understood. We present the results of multifrequency observations of IRAS F01004−2237 conducted by the Very Long Baseline Array at 2.3 and 8.4 GHz. Compact 8.4 GHz continuum emission was detected on a 1 pc scale in the nuclear region with an intrinsic brightness temperature of 108.1 K suggesting that the radio source originated from an AGN, potentially driving the extended emission. In contrast, no significant emission was observed at 2.3 GHz, indicating the presence of low-frequency absorption. This absorption cannot be attributed solely to synchrotron self-absorption; alternatively, free–free absorption due to thermal plasma is mainly at work in the spectrum. From combined perspectives, including mid-infrared and X-ray data, the AGN is obscured in a dense environment. The kinetic power of the nonthermal jet, as inferred from the extended emission, can play a more important role in dispersing the surrounding medium than the thermal outflow in IRAS F01004−2237. These findings hint that jet activities in ULIRGs may contribute to AGN feedback during galaxy evolution induced by merger events. [ABSTRACT FROM AUTHOR]

Context. Massive star winds are known to be responsible for X-ray emission arising from wind plasma heated by the strong shocks up to temperatures of 106–107 K in the case of colliding wind binaries. The investigation of X-ray emission from massive stars thus constitutes a valuable tool for identifying binaries, which is otherwise a difficult task using classical techniques. Aims. We investigated thermal and nonthermal X-ray emission from the massive O-type star HD 93250 to unveil its binary orbital parameters independently. Methods. To meet our goal, we analyzed X-ray data obtained with European Photon Imaging Camera on board XMM-Newton spanning over ~19 yr. Additionally, we analyzed NuSTAR observations of HD 93250 taken at various epochs. Results. We determine the variability timescale of the X-ray emission to be 193.8±1.3d, in full agreement with the 194.3±0.4d period derived from the astrometric orbit. The X-ray spectrum of HD 93250 is well explained by a three-temperature thermal plasma emission model with temperatures of 0.26, 1.0, and 3.3 keV. The resulting X-ray flux varies in compliance with the typical colliding wind emission from eccentric massive binaries where it enhances near periastron passage and decreases gradually close to apastron in proportion to the inverse of the binary separation. The periastron-to-apastron X-ray emission ratio points to an eccentricity range of 0.20–0.25, once again in agreement with the previously determined astrometric orbit. Finally, we do not detect any hard X-ray emission attributable to nonthermal emission above 10 keV. Conclusions. Given the derived plasma temperature, the strong phase-locked variability, and the significant over-luminosity in X-rays, we establish that the X-ray emission from HD 93250 is dominated by the colliding-wind region. Our results lend support to the idea that X-ray time analysis of massive stars constitutes a relevant tool for investigating their multiplicity and for extracting relevant information on their basic orbital parameters – such as period and eccentricity – independently of any orbital solution derived from classical techniques. [ABSTRACT FROM AUTHOR]

NaBH4 is an attractive candidate for closed-loop hydrogen generation in small practical applications owing to its ambient condition hydrogen release mechanism, non-toxic byproduct, ability to regenerate, and stability at ambient conditions. The hydrolysis of NaBH4 requires a catalyst to accelerate the hydrogen generation process and cobalt oxide is one such promising catalyst in this reaction. The surface species and crystalline phases of cobalt oxide catalysts play an important role in determining the hydrogen generation rate and overall hydrolysis process. In this study, cobalt oxide nanoparticles are synthesized by a thermal plasma route. The two crystalline phases, namely c-CoO and Co3O4, are tuned using thermal plasma operating conditions. The catalysts so obtained have been thoroughly characterized using analytical techniques like XRD, XPS, HR-TEM, etc. Furthermore, the catalyst was used for hydrogen production in the hydrolysis process of NaBH4. The ex situ X-ray photoelectron spectra recorded at different stages of the hydrolysis process have been extensively used to understand surface modifications occurring at the surface of the catalyst. The Co+3/Co+2 ratio and attachment of other species during hydrolysis analyzed using XPS are correlated with the overall hydrolysis reaction before and after catalysis. It was concluded that the presence of the c-CoO (i.e. initial Co+2 species presence) phase brings stability to hydrogen production in that cycle. [ABSTRACT FROM AUTHOR]

NaBH4 is an attractive candidate for closed-loop hydrogen generation in small practical applications owing to its ambient condition hydrogen release mechanism, non-toxic byproduct, ability to regenerate, and stability at ambient conditions. The hydrolysis of NaBH4 requires a catalyst to accelerate the hydrogen generation process and cobalt oxide is one such promising catalyst in this reaction. The surface species and crystalline phases of cobalt oxide catalysts play an important role in determining the hydrogen generation rate and overall hydrolysis process. In this study, cobalt oxide nanoparticles are synthesized by a thermal plasma route. The two crystalline phases, namely c-CoO and Co3O4, are tuned using thermal plasma operating conditions. The catalysts so obtained have been thoroughly characterized using analytical techniques like XRD, XPS, HR-TEM, etc. Furthermore, the catalyst was used for hydrogen production in the hydrolysis process of NaBH4. The ex situ X-ray photoelectron spectra recorded at different stages of the hydrolysis process have been extensively used to understand surface modifications occurring at the surface of the catalyst. The Co+3/Co+2 ratio and attachment of other species during hydrolysis analyzed using XPS are correlated with the overall hydrolysis reaction before and after catalysis. It was concluded that the presence of the c-CoO (i.e. initial Co+2 species presence) phase brings stability to hydrogen production in that cycle. [ABSTRACT FROM AUTHOR]

Considering the urgent need for green energy carriers, hydrogen became a promising substitute for fossil fuel production via sustainable approach. Therefore, developing efficient photocatalysts using solar energy is the main issue. Here, we report experimental and computational studies on nature and influence of oxygen vacancies in different atomic layers of defective TiO 2-x nanotubes photocatalysts. Although there are several studies that opened a new avenue to understand how to fabricate suboxide TiO 2-x , there is no any comparative study reported on two main oxygen reduction techniques yet: cold plasma treatment and thermal hydrogenation. Oxygen vacancies and Ti3+ species produced by plasma reduction in a mixed Ar/H 2 (90/10) under pressure of 10−3 Torr efficiently increase charge carrier life time (at optimum 15 W power) resulting in higher H 2 production rate and significant incident photon to current efficiency (60%) in comparison with point defects produced by hydrogenation treatment. Various techniques utilized to fabricate oxygen deficient TiO 2-x can lead to the creation of defects in specific atomic layers within the crystal structure. Therefore, we develop an ab initio model of the oxygen vacancies' formation at different depths of TiO 2 slabs to study the effect of defects' position in the crystal lattice on electronic structure against energy levels of water splitting reaction. This research provides a new and deep insight for designing suboxide black TiO 2-x for efficient photocatalytic reactions especially for green energy production and environmental remediation. [Display omitted] • Oxygen vacancies in TiO 2-x nanotubes enhance H 2 production and IPCE efficiency. • Cold plasma generates surface defects, while thermal treatment creates bulk defects. • Surface oxygen vacancies and Ti3+ boost carrier lifetime and photocatalytic activity. • Ab initio model investigates the impact of defect position on electronic structure. • This research guides the design of TiO 2-x for efficient green energy production. [ABSTRACT FROM AUTHOR]

The aims of this study encompass the characterization of process parameters and the antimicrobial potential during operation of a novel non-thermal plasma (NTP) source in a duct system containing a particulate matter (PM) filter thus mimicking the interior of an air purifier. Simulating conditions of a long-term operation scenario, in which bacterial aerosols in indoor environments accumulate on PM filters, the filter surfaces were artificially inoculated with Escherichia coli (E. coli) and exposed to an air stream enriched with reactive species. Electrical power consumption, key plasma parameters, volume flow and air flow velocity, reactive gas species concentrations as well as inactivation rates of E. coli were assessed. The NTP operated at a gas temperature close to ambient air temperature and featured a mean electron energy of 9.4 eV and an electron density of 1∙1019 m−3. Ozone was found to be the dominating reactive gas species with concentrations of approx. 10 ppm in close vicinity to the PM filters. An inactivation rate of 99.96 % could be observed after exposure of the PM filters to the gas stream for 15 min. This inactivation efficiency appears very competitive in combating realistic bacterial aerosol concentrations in indoor environments. [ABSTRACT FROM AUTHOR]

The constant growth in the share of renewable electricity and the need to reduce CO2 emissions create prospects for the development of non‐thermal plasma (NTP) pyrolysis of heavy oil. NTP pyrolysis requires only electricity and does not require heating of raw materials to high temperatures, which significantly reduces the carbon footprint during processing. This paper investigates the characteristics of NTP pyrolysis of vacuum gas oil under the action of electric microsecond discharges in the liquid phase, depending on the voltage of the current source 300–700 V to optimize energy consumption, conversion of raw materials, and increase the yield of commercial demand products. [ABSTRACT FROM AUTHOR]

The use of non thermal plasma (NTP) to improve indoor air quality (IAQ) has grown considerably in recent years. This paper demonstrates the advantage of NTP for IAQ improvement in terms of particulate matter (PM) removal. The PM removal mechanism using active air ions and radicals has been investigated. From the developed dielectric barreir discharge (DBD) air plasma reactor, the total PM removal efficiency of 61.72% has been achieved at an optimised concentration of negative and positive air ions in 2 hours of continuous operation. Due to the utilised sensor's limit of quantification (LOQ), PM 2.5 and PM 10 have been reduced to a certain value. The findings revealed that DBD air plasma can be effectively used for PM removal in an enclosed environment. [ABSTRACT FROM AUTHOR]

Introduction. One of the directions of development of plasma technologies consists in the formation of gas-metal plasma formations and throwing them to a certain distance. Known thrusters of plasma formation either have an electrode system that is prone to erosion, or a discharge system in a solid dielectric substance in which ablation occurs, or a complex gas-dynamic system with fuel supply. They do not provide acceleration of plasma formation in the atmosphere for a significant distance. Purpose. A theoretical and experimental study of electromechanical and thermophysical processes in a plasma thruster, which ensures the formation of a plasma formation due to thermal ionization by an induced current in a thin conductor layer during a high-voltage discharge on an inductor and the accelerating of a plasma formation in the atmosphere for a significant distance. Methodology. The proposed concept of a plasma thruster, in which the inductor inductively interacts with a combined armature, which includes an aluminum armature in the form of a thin (0.5-1 μm) foil, a copper armature made of a thicker foil (35-50 μm).On the basis of a mathematical model that takes into account the uneven distribution of currents in the inductor and conductive armatures, the features of the process of acceleration the combined armature in the atmosphere were established and experimental studies were carried out. Results. The electromechanical and thermal characteristics of the plasma thruster were calculated. It was established that the choice of the thickness of the dielectric layer of the armature, to which the aluminum and copper armatures are attached, is determined by the energy balance between the heating temperature of the aluminum armature and the electromechanical indicators of the thrower. Scientific novelty. It was experimentally established that the greatest density and homogeneity is observed in the middle of the plasma formation, which has the shape of a torus, moving away from the dielectric sheet on which the aluminum armature was located. As the voltage of the capacitive energy storage increases, the induced current density in the armature increases and the plasma formation becomes more uniform. Practical value. In comparison with the experimental results, the calculated current in the inductor coincides both in shape and in magnitude with an accuracy of 7 %. The biggest difference between the calculated and experimental currents of the inductor occurs when the aluminum armature is thermally destroyed. The transition of an aluminum armature into a plasma formation depends significantly on the voltage of the capacitive energy storage. References 26, figures 16. [ABSTRACT FROM AUTHOR]