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Optical emission spectroscopy studies of vanadium plasma in a cathodic-arc discharge in a nitrogen atmosphere have been carried out. Spectral lines of neutral atoms and ions of the cathode material V, V1+, and V2+, and nitrogen N2 and N2+ were observed in the discharge plasma. Analysis and comparison of the intensity of vanadium and nitrogen spectral lines as a function of nitrogen pressure showed that in vacuum excited ions V2+ and V+ are registered, with increasing pressure, the lines V+*, N2*, and N2+* are observed, and at pressures above 0.5 Pa, the neutral vanadium lines are additionally registered. The electron temperature of Te decreases from 5.9 to 3–4 eV with increasing pressure. Studies of cross-sectional scanning electron microscopy images of VN coatings deposited at different nitrogen pressures have shown that a dense, homogeneous, fine-grained microstructure is formed in the coating when the number of neutral V in the plasma is low, while in the presence of a large number of neutrals, the coating structure changes to a dense structure with columnar growth. [ABSTRACT FROM AUTHOR]

Plasma technology is based on a simple physical principle. When more energy enters the gas, it ionizes and becomes the fourth state of matter, the energy-dense plasma. The studies carried out within the scope of this study were designed to create microchannels on lamellar glass using an improved redesign of the current plasma arc device, which is the main subject of the paper. The created microchannel is examined at the microscale. Experimental analysis was conducted considering the effect of plasma on the effect of microchannel quality. We performed an experimental design study to determine the optimal parameter levels for improving microchannel quality. The predicted results have been validated with the experimental results. An experimental design study provides useful results, such as information about the distance between the probes, pulse duration, and material temperature, which enhances the channel dimensions. The improved device can be utilized effectively to establish microchannel processing in practice. [ABSTRACT FROM AUTHOR]

Electrical and fast imaging measurements are performed on an experimental device designed to study the dynamics of electric arcs in the DC regime. The work presented here investigates the relationship between electrical fluctuations and material ejection from the electrode surface. Cross-analysis of the electrical and imaging data reveals a significant correlation between electrical fluctuations in the kHz range and particle emission from the electrode surface. Different types of ejection are presented and a study of the dynamics of the ejected particles is carried out through the analysis of a statistically significant number of trajectories. [ABSTRACT FROM AUTHOR]

Background: Silver nanoparticles are extensively researched for their antimicrobial properties. Cold atmospheric plasma, containing reactive oxygen and nitrogen species, is increasingly used for disinfecting microbes, wound healing, and cancer treatment. Therefore, this study examined the effect of water activated by dielectric barrier discharge (DBD) plasma and gliding arc discharge plasma on the antimicrobial activity of silver nanoparticles from Alborzia kermanshahica. Methods: Silver nanoparticles were synthesized using the boiling method, as well as biomass from Alborzia kermanshahica extract grown in water activated by DBD and GA plasma. The physicochemical properties of the synthesized nanoparticles were evaluated using UV-vis spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, dynamic light scattering (DLS), zeta potential analysis, transmission electron microscopy (TEM), and gas chromatography-mass spectrometry (GC-MS) analysis. Additionally, the disk diffusion method was used to assess the antimicrobial efficacy of the manufactured nanoparticles against both Gram-positive and Gram-negative bacteria. Results: The spectroscopy results verified the presence of silver nanoparticles, indicating their biosynthesis. The highest amount of absorption (1.049) belonged to the nanoparticles synthesized by boiling under GA plasma conditions. Comparing the FTIR spectra of the plasma-treated samples with DBD and GA revealed that the DBD-treated samples had more intense peaks, indicating that the DBD method proved to be more effective in enhancing the functional groups on the silver nanoparticles. The DLS results revealed that the boiling method synthesized silver nanoparticles under DBD plasma treatment had a smaller particle size (149.89 nm) with a PDI of 0.251 compared to the GA method, and the DBD method produced nanoparticles with a higher zeta potential (27.7 mV) than the GA method, indicating greater stability of the biosynthesized nanoparticles. Moreover, the highest antimicrobial properties against E. coli (14.333 ± 0.47 mm) were found in the DBD-treated nanoparticles. TEM tests confirmed that spherical nanoparticles attacked the E. coli bacterial membrane, causing cell membrane destruction and cell death. The GC-MS results showed that compounds like 2-methylfuran, 3-methylbutanal, 2-methylbutanal, 3-hydroxy-2-butanone, benzaldehyde, 2-phenylethanol, and 3-octen-2-ol were much higher in the samples that were treated with DBD compared to the samples that were treated with GA plasma. Conclusion: The research indicated that DBD plasma was more efficient than GA plasma in boosting the antimicrobial characteristics of nanoparticles. These results might be a cornerstone for future advancements in utilizing cold plasma to create nanoparticles with enhanced antimicrobial properties. [ABSTRACT FROM AUTHOR]

A unified one-dimensional model of an arc plasma in air, between copper electrodes, that includes the change of the gap distance is presented. The occurrence of multiple reversals of the electric field and the anode voltage drop is observed. The evolution of the spatial distribution of the electron and heavy particle temperatures with the gap distance and the opening speed is also studied. The model quantitatively predicts a number of plasma properties under conditions that are relevant to the contact separation in low-voltage switching devices. [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]

Ni-WC composite coating was prepared on Q235 steel substrate by plasma transfer arc (PTA) with welding current ranging from 70 A to 85 A. The results show that the dissolution behaviour of WC particles and the elemental diffusion at the interface promoted by the increased welding current promote the formation and evolution of precipitates, including M 7 (B, C) 3 and M 6 C. The increased current reduced the volume fraction of WC particles in the coating, but increased that of the precipitates. At welding currents of 75 A and 80 A, dendritic-like M 7 (B, C) 3 presented a regular distribution at the bottom of the coating. At a welding current of 80 A, M 6 C phase began to form at the bottom of the coating. When the welding current reached 85 A, the dendritic structure was broken, and the M 6 C phase aggregated and grew. The Ni-WC coating had visible delamination. WC particles at the upper part of the coating dissolved more severely compared to those at the middle and bottom of the coating. Ni 3 Si compound was formed at the upper and middle of the coating, and it had a crystal orientation relationship of [011] Ni3Si ∥[011] γ-Ni , (11-1) Ni3Si ∥(11-1) γ-Ni , (−200) Ni3Si ∥(-200) γ-Ni , (-11-1) Ni3Si 1.3° from (-11-1) γ-Ni with γ-Ni. The average hardness of the coating decreased slightly due to the dissolution of WC, but the hardness at the interface increased, showing an improved bonding of the interface. The newly formed high hardness precipitates can share the load coming from the friction paired ball, thus reducing CoF and wear loss of the coating. [ABSTRACT FROM AUTHOR]

Electric arcs are a necessary heat source in many industrial processes that take place in Submerged Arc Furnaces (SAFs). Arcs exhibit non-linear electrical characteristics and behave in a complex manner. Therefore, an improved understanding of their behavior enables better control of furnace operation. Modeling of industrial arcs is a multiphysics process that involves simultaneously solving several coupled physical phenomena, such as electromagnetics, fluid dynamics, and heat transfer, including a radiative heat transfer from the plasma arc. Coupling fluid dynamics and electromagnetics is known as Magnetohydrodynamics (MHD). For practical applications, however, there are also simpler approaches to arc modeling, either based on simplified physical principles or empirical behavior. In this paper, a combined Cassie–Mayr model (CMM) and a channel arc model (CAM) are implemented and coupled with a submerged arc furnace electrical circuit model. The complete circuit model parameters such as resistances and inductances are estimated using modeling of a full size furnace, and then, actual measurements from a SAF are used to validate the models by comparing current and voltage waveform. Both models are then used to estimate harmonic distortion in a SAF for different arc current ratios, which should help operators to estimate the arc current in real time thus be able to lower and raise the electrode to keep operating conditions constant. [ABSTRACT FROM AUTHOR]

In the present study, 3D non-woven needle-punched preform (NPP) Cf–SiCm composite with 7.5 pct volume fraction of carbon fiber is prepared via liquid silicon infiltration technique and characterized for microstructure, phase formation and mechanical behaviors. Additionally, the composite is subjected to plasma arc jet tests for evaluation of ablation resistance under ultra-high temperature oxidation environment. The dense composite (density ~ 2.5 to 2.6 g/cm3) contains β-SiC phase due to the reaction between infiltrated molten silicon and carbon matrix surrounding the carbon fibers. The resultant Cf–SiCm composite shows high hardness and high abrasion resistance due to a higher proportion of hard SiC matrix as well as exhibits various toughening mechanisms from the carbon fiber reinforcement causing a delay in fracture. It also contains excellent resistance to thermal shock and thermo-oxidative erosion resistance during plasma arc jet ablation test without any visible crack or damage on the exposed surface. [ABSTRACT FROM AUTHOR]

Modeling analysis of underwater pulsed arc discharge can predict the characteristics of plasma channels, providing theoretical guidance for the practical application of underwater pulsed discharge. Due to the complexity of experimental diagnostics for 'kA'-level underwater pulsed discharge, there is currently a lack of precise experimental data to support the initial value selection and result optimization of the modeling. This paper established a plasma channel model for underwater pulsed arc discharge. In conjunction with the Saha ionization equilibrium equation, the model was capable of simulating the current, pressure, temperature, and electron density of the channel after gap breakdown. By utilizing spectroscopic diagnostic data and a multi-objective optimization algorithm, the initial values and key parameters of the model were reasonably determined. The simulation results were in good agreement with the experimental diagnostic results, reasonably representing the trends in electron density and blackbody radiation temperature. Moreover, the model was applicable for reasonably explaining the emission spectral mechanism of the arc channel and shock waves prediction under different discharge conditions. [ABSTRACT FROM AUTHOR]

Heterostructure engineering has been proposed as a promising approach to construct high-efficiency bifunctional electrocatalyst for overall water splitting. Integrated transition metal and metal oxide heterointerfaces with carbon nanomaterials are designed to facilitate electrocatalytic performance toward overall water splitting. Fe/MnO heterostructures are fabricated on graphene using a one-step DC arc plasma technology. In this way, increased electrochemically active specific areas, accelerated charge transfer, and proper interfacial electronic structure can be achieved. Benefiting from the synergistic effect of multiple materials, fabricated Fe/MnO/graphene heterointerfaces can make the redistribution of electrons between heterointerfaces, which effectively optimizes adsorption/desorption energy of the reaction intermediates. Fe/MnO/graphene delivers excellent catalytic activity with only 362 mV and 339 mV overpotential to reach current density of 10 mA cm−2 for OER and HER and exceptional long-term stability in alkaline solution. As electrocatalyst at both the cathode and the anode of an alkaline electrolyzer simultaneously, Fe/MnO/graphene electrocatalyst requires a cell voltage of 1.987 V at a current density of 10 mA cm−2 for overall water splitting. Therefore, this work offers a feasible route to construct hierarchically nanohybrids as bifunctional electrocatalysts by combining transition metal and metal oxide with carbon nanomaterials. • Fe–MnO/C nanocomposite with heterointerfaces is prepared by arc-discharge method. • The heterogeneous nanostructures exhibit prominent performance of water splitting. • The coupling and synergistic effects reduce the kinetic barriers of HER and OER. [ABSTRACT FROM AUTHOR]

In this paper, the laser and arc are shifted laterally to change the position and energy distribution of arc discharge, which provides a new idea and theoretical basis for solving the narrow gap welding defects of titanium alloy thick plate. In this study, the effect of transverse offset distance between laser and arc (DLAP) on the discharge characteristics of hybrid heat source coupling and the flow characteristics of molten pool was studied by using the welding method of plate surfacing. The dynamic behavior of the arc plasma, the molten pool, and the keyhole was monitored in real time, and the plasma spectral information was collected to analyze its energy distribution characteristics. The results show that under different DLAP conditions, the charged plasma of the hybrid heat source has two different states: strong coupling state and separation state. When DLAP = 2 mm, the plasma at the center of the keyhole has the strongest spectral intensity, the lowest electron temperature, and the highest electron density, which are 15174, 9546 K, and 1.88 × 1017/cm3, respectively. At this time, the weld pool and keyhole have the maximum arc pressure and Marangoni force, resulting in an increase in the flow velocity of the weld pool and an increase in the area of the weld pool. [ABSTRACT FROM AUTHOR]

NiAl intermetallic-based hardfacing coatings were processed by in situ synthesis from elemental Ni and Al powders mixtures, by Directed Energy Deposition - Plasma Transferred Arc (DED-PTA). The exothermic nature of NiAl synthesis promotes the formation of columnar grains, which do not contribute to mitigate the low toughness of the material at room temperature, limiting its use. Refining the microstructure is a path to overcome this limitation and the approach used took advantage of tungsten carbide nanoparticles (WC-NPs) to limit grain growth during solidification. During preparation of powder mixtures, the adhesion of 1 wt.%WC-NPs to the surface of Ni particles (which act as carriers) helps to reduce the tendency to agglomeration. However, this approach proved to be ineffective for the in situ synthesis of NiAl, since the NPs form a film of molten material on the Ni particle surface as they cross the plasma arc, limiting the interdiffusion of Ni and Al, compromising the synthesis of the aluminide alloy. The present study assessed this challenge by investigating the amount of NP carriers, i.e, the proportion of Ni particles that carry the NPs, that allows both for the synthesis of NiAl, and grain refining due to the WC-NPs. Results show that β-NiAl phase was successfully formed in multi-layer coatings, processed in situ by DED-PTA. Powder mixtures containing 50% and 70% NP carriers promoted a progressive reduction in grain size by the addition of 1 wt.% WC-NPs in the Ni+Al powder mixture, followed by an increase in hardness. [ABSTRACT FROM AUTHOR]

The mixing process of the cathodic jets is an important connection between the metal surface and the plasma arc column, which helps to understand the diffusion mechanism of the vacuum arc and guides the vacuum switch design. The interaction process of double cathode jets is simulated using a 3D magnetohydrodynamic method. This study analyzes the evolution of plasma parameters as the double cathode jets transition from a separated state to a mixed state. The results indicate that a mixed single-peaked jet ultimately forms at the exit when the double cathode jets are present at the inlet of the cathode surface. The transition from the separated state to the mixed state occurs further away from the cathode surface as the inlet current density of the jets increases from 3 to 5 × 109 A/m2. Additionally, the asymmetry in the current density of the double cathode jets causes the peaks of the mixed single-peak current density and ion temperature to be skewed toward the direction of the lower inlet current density. In cases where the inlet current direction is asymmetric, the peaks shift toward the direction where the inlet current is perpendicular to the cathode surface. Furthermore, the outward expansion acceleration trend of the plasma aligns well with the results from single-jet numerical simulations. [ABSTRACT FROM AUTHOR]

The paper investigates the structure and properties of the surface layers of AA5056 and AA2024 aluminum alloy plates 35 to 40 mm thick after reverse-polarity plasma cutting. It is shown that for alloys with varied parameters of the heat capacity, plasma cutting conditions are the same. At the best plasma cutting parameters, the cut geometry shows the lowest distortion. It is found that the cutting surface distortion occurs in exceeding the optimum heat input of the plasma arc. Conversely, at the reduced heat input, the alloy plate cannot be cut to its full thickness. Most of cutting modes provide the higher surface roughness, while the roughness of the upper edge cut reduces relative to the central and lower areas. [ABSTRACT FROM AUTHOR]

This investigation conducted an experimental study of flow control in a Mach 2.5 cavity combustor using arc plasma energy deposition (APED), implemented both with and without injection. APED was produced by a pulsed arc discharge plasma actuator at frequencies of 5, 10, 15, and 20 kHz. The objective is to elucidate the influence and underlying mechanisms of APED on the flow dynamics by statistically evaluating time-resolved schlieren images and monitoring pressure fluctuations throughout the control process. The findings indicate that APED significantly modifies the energy distribution across unsteady modes and alters the pressure distribution within the flow field. In scenarios without injection, high-frequency discharge triggers oscillations in the shear layer; the impact of precursor shocks and thermal bubbles diminishes the magnitude and fluctuations of both shear layer-induced and internal shocks. Conversely, in the injection scenario, high-frequency discharge, in conjunction with oscillations of the boundary layer and bow shocks, amplifies the oscillation amplitude and frequency of jet vortex shedding. Additionally, APED intensifies the pulsation and penetration depth of the jet, which is essential for enhancing the mixing efficiency of the incoming flow with fuel. The effectiveness of the control is positively correlated with the actuator's discharge frequency, or its average power, within the confines of this study. [ABSTRACT FROM AUTHOR]

A novel plasma reactor is being investigated for green NOx production, crucial for nitrate‐based fertilizer manufacturing. Various parameters, including air flow rates, gas ratios, ozone, and catalyst effects are explored for NO → NO2 conversion. NOx concentrations reach ~0.6 vol%, with a total production of ~9.7 gr/h and energy cost of ~3.0 mJ/mol, notably favorable for atmospheric gliding arc plasma. Selectivity (~75%) towards NO2 is achieved with ozone addition or catalytic treatment, pivotal for nitrate fertilizer and HNO3 production. [ABSTRACT FROM AUTHOR]

According to the control mechanism of surface arc discharge plasma actuation on the flow and combustion of flameholder, the applicability of the phenomenological model of surface arc discharge is verified. And, the effects of different actuation positions and actuation intensities on the flow field structure, fuel atomization, ignition delay and flame stability in the flameholder are systematically analyzed. The results show that different actuation positions have a significant impact on the flow field structure, especially when the actuation energy is effectively concentrated and a strong actuation region is formed, which leads to the expansion of the recirculation zone, which in turn promotes fuel atomization, slows down the ignition delay and increases the average flame temperature. At the same time, with the increase of actuation intensity, the length of the recirculation zone, the mixing efficiency and the combustion efficiency increased linearly. [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]

Fluorinated gases, e.g., CF3I, C3F8, C4F8, C4F7N, and C5F10O, show potential to replace SF6 in power industry due to their high dielectric strength and low global warming potential. However, particle condensation from arc plasmas of these compounds may reduce dielectric performance. We perform a systematic investigation of particle condensation in two-temperature (2T) arc plasmas of various SF6 replacements mixed with CO2, N2, and O2, by the Gibbs free energy minimization and entropy maximization methods. The influences of buffer gases, non-equilibrium degree, and gas pressure on particle condensation are discussed in various cases. The results indicate that O2 is necessary to prevent graphite formation in carbon–fluorine gaseous arcs, and specific mixing ratios of CO2 and N2 are required to avoid graphite and iodine crystals in CF3I arc plasmas. The relationship between condensation temperature and non-equilibrium degree is complex, with peaks and valleys observed for graphite and iodine crystal condensation temperatures. Moreover, different calculation methods (Gibbs free energy minimization versus entropy maximization) show varying sensitivity of condensation temperatures to pressure changes. All the above findings highlight the importance of considering non-equilibrium effects and multiple condensed species in evaluating arc plasma compositions of SF6 replacements. [ABSTRACT FROM AUTHOR]

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

This investigation reports the influence of Ti–C and Ti–W cathode composition on an industrial-scale dc vacuum arc plasma source. Further, we analyze the influence of plasma generation and plasma properties on the resulting cathode surface after the operation and on basic film properties. The results are compared with previous work focused on Ti–Al and Ti–Si compound cathodes. For all Ti–X compound cathodes (X = W, C, Al, and Si), a direct correlation between plasma ion energy/charge and the cohesive energy of the cathode was demonstrated, with a small number of exceptions to a limited set of specific cathode compositions. Hence, the "velocity rule" and effects from different electron temperatures were suggested to be important for gaining a more detailed understanding of plasma properties. A discrepancy was found between the cathode and plasma ion composition, though the difference was reduced in a corresponding comparison between the cathode and the deposited film composition. A significant contribution of a flux of neutrals and/or macroparticles to the final film composition was, therefore, suggested. The effect of the melting point of the cathode phase composition on the intensity of macroparticle generation and the smoothness of the cathode surface operation was also investigated. The presented results contribute to the fundamental understanding of vacuum arc plasma generation and transport and are of importance for further development and applicability of Ti-based coatings from arc deposition. [ABSTRACT FROM AUTHOR]

Electro-arc machining (EAM) is a new electrical discharge machining method based on thermal energy. A large amount of thermal energy is released during arc formation to melt and vaporize the workpiece material. Many factors affect arc machining performance, such as electrical parameters (peak current, etc.), non-electrical parameters (flushing pressure, etc.), workpiece and electrode shape, and material parameters. The electrode shape influences the machining performance. Single-factor, single-pulse arc discharge experiments are carried out to evaluate the effect of the electrode's shape. The polarity effect is verified, and the following results are obtained. For the same workpiece conditions, the arc pit diameter is larger for positive polarity than for negative polarity, suggesting that the arc machining performance is also better for positive polarity. The radius of curvature of the crater has a larger influence than the crater diameter. If a larger etching volume is required, the radius of curvature can be increased, but the etching depth is slightly reduced. The positive and negative polarity also affect the arc plasma characteristic. The compression-expansion effect of the plasma is more pronounced when the direct current is large and positive polarity is used. Waveform analysis shows that the processing stability is higher for positive polarity, whereas negative polarity is more likely to result in bridges and short circuits. As the radius of curvature increases, the processing time, processing instability, and the height of the crater wall increase. The height of the crater wall is higher for positive polarity than for negative polarity. [ABSTRACT FROM AUTHOR]

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

The 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]

Excessive alternating current (AC) arcs generated in electric systems will accumulate heat and easily cause fire. This paper studies the thermal characteristics of different numbers of AC arc plasma generated in a short gap of copper-cored wires in the air. The number of AC arcs is controlled in the AC arc experiment and an infrared thermal imager measures the temperature change at the specified position. Based on magnetohydrodynamics (MHD), a two-dimensional axisymmetric AC arc discharge numerical simulation model is established. The volt-ampere characteristic of the AC arc is used to solve the MHD simulation model to obtain the same 'zero current' characteristics as the real AC arc in the experiment. A large amount of heat accumulates in the electrode gaps when the arc generation, and then the heat dissipates in the 'zero current' stage. The continuously generated arc makes the temperature higher. The volume of the space area with a temperature higher than 10,000 K increases with the arc current, but is unrelated to the number of arcs. The volume of the space area with a temperature higher than 524.15 K and the temperature on the electrode are both positively correlated with the number of AC arcs and arc current. The results of this study can provide a reference for the detection standard of AC arc faults and the prevention of electrical fire. [ABSTRACT FROM AUTHOR]

The article describes modern methods for controlling and optimizing the energy mode of melting in electric arc furnaces and units for out-of-furnace steel processing using optical emission spectroscopy systems. These systems enable the determination of melt and slag temperatures, plasma temperatures in the arc combustion area, and slag composition, as well as the analysis of emission intensity from the melt and slag surfaces. The analysis revealed that depending on the range of steel to be smelted and the peculiarities of smelting technology at a particular electric arc steel-making furnace, control systems for smelting monitoring can be developed according to the obtained indicators of one or a combination of the abovementioned parameters. [ABSTRACT FROM AUTHOR]

The lifespan of the guide rail is a bottleneck restricting the operational life of electromagnetic railguns. A well‐designed arc extinguishing device can reduce the arcing erosion caused by residual currents within the guide rail. The CuW alloy is widely used in the high‐pressure arc extinction field due to its excellent electrical and thermal conductivity, high strength, and hardness. Based on the theory of equilibrium state arc plasma, a finite element model of the air arc‐CuW electrode coupling in the arc extinction device was established to study millisecond‐level arc initiation, evolution, extinguishing characteristics, and distribution patterns under extreme and harsh operational conditions with a current input of 110 kA. The highest temperature in the arc column region was found to exceed 50,000 K. The study elucidated the influence of arc extinction device parameters on arc evolution, breakdown time, and breakdown voltage. Consequently, it established that the R70 spherical electrode exhibits optimal arc extinguishing characteristics. The aim of this research is to provide theoretical support for optimizing the arc suppression device. Additionally, experiments on high‐speed and high‐current arc extinction device discharges were conducted to validate the finite element analysis results regarding arc diffusion patterns and electrode erosion. [ABSTRACT FROM AUTHOR]

The electrohydraulic effect induced by underwater arc discharge is an efficient way to generate controllable, high-intensity shock waves. However, the development process of underwater arc discharge involves the complex coupling of plasma arc, gas bubble, and liquid medium, of which the evolution mechanism is not well understood. In this paper, the underwater arc discharge process at a millisecond pulse (>50 ms) was investigated by high-speed shadow imaging and colorimetric temperature measurement, and a simulation model of bubble pulsation was proposed to quantitatively estimate the state variation and energy transfer of the gas bubble. The results indicate that the whole arc discharge process can be categorized into three successive stages: short-period oscillation, long-period oscillation, and quasi-steady state. The vapor inside the bubble can reach a supercritical state (827 K and 140 MPa) at the minimum bubble radius. The simulation shows that the light radiation absorption and the heat conduct loss through metal electrodes are the two dominant factors influencing the pulsation of the bubble, and further analysis indicates that the dynamic evolution of the arc determines the bubble pulsation mode. Our findings demonstrate why and how repetitive electrohydraulic shock waves can be generated by a single long pulse underwater arc discharge, providing a low-cost way of shock wave generator based on an AC/DC high-voltage power source. [ABSTRACT FROM AUTHOR]

Yttria-stabilized zirconia hollow spherical powder (YSZ-HOSP) is a widely utilized ceramic material in thermal barrier coatings (TBCs). Within the category of YSZ-HOSP, yttria-stabilized zirconia spherical thin-walled hollow-shell powder (YSZ-STHS) displays immense potential for producing TBCs with minimal inter-lamellar porosity and cracks. Arc plasma torch equipped with flow-shaping nozzle shows promise for preparing YSZ-STHS. However, there is limited research on the impact of the nozzle geometry on plasma flow field characteristics and the resulting effect on the quality of YSZ-HOSP, particularly in terms of spheroidization ratio, hollow-shell powder ratio, and shell thickness. To achieve controllable preparation of YSZ-STHS in arc plasma spheroidization, this paper proposed a novel model for the formation of YSZ-HOSP under different plasma flow characteristics, including high-speed compressing flow field, intermediate-speed critical flow field, and low-speed expanding flow field. These different plasma flow characteristics were achieved by changing the nozzle diameter and investigated by both numerical simulation and experiments in terms of plasma flow characteristics, electro-thermal characteristics, and the quality of the YSZ-HOSP. Results reveal that YSZ-HOSP prepared with high-speed compressing flow field resulted in a low hollow-shell powder ratio, while low-speed expanding flow field led to an over-thick shell. Conversely, the intermediate-speed critical flow field demonstrates relatively high thermal efficiency and enthalpy, along with moderate jet temperature and velocity, resulting in YSZ-STHS with a spheroidization ratio of 96.6 %, a hollow-shell powder ratio of 92.5 %, and a mean shell thickness of 3.49 μm. Therefore, it is evident that manipulating plasma flow characteristics allows for the controlled preparation of YSZ-STHS. [Display omitted] [ABSTRACT FROM AUTHOR]

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The effective welding of a 6 mm thick TA2 pure titanium medium-thickness plate was achieved by laser–arc hybrid welding (LAHW) with helium–argon mixed shielding gas. Conducted research on the influence of helium–argon mixed shielding gas on plasma and arc characteristics during welding, and its further impact on the microstructure, internal porosity defects, tensile properties, and corrosion resistance of welded joints was explored. The study demonstrated that under the shielding gas with 75% helium, the arc width narrowed significantly from 6.96 mm to 2.61 mm, achieving a 63% reduction, which enhanced the concentration of arc heat flux density. Achieved a well-formed weld with no surface spatter and significantly reduced the internal porosity rate from 3.02% to 0.47%, which is an 84% decrease. Tensile fractures are located in the base material, all exhibiting plastic failure. The corrosion resistance of the welded joint initially increased and then decreased with the increase of helium content in the shielding gas, peaking at 75% helium content. [ABSTRACT FROM AUTHOR]

Plasma seed pretreatment is an important means to rapidly improve seed quality. The studies on plasma-generating devices suitable for continuous seed pretreatment at atmospheric pressure have been relatively limited. Gliding arc discharge can generate atmospheric pressure plasma at room temperature, which provides a new way to use plasma to treat seeds at ambient temperature and pressure. By analyzing the influence of structural characteristics, such as gliding arc electrode shape, discharge distance, and electrode opening angle on plasma distribution, a plasma seed treatment method based on negative pressure guidance was proposed, and the electrode structure was optimized. The results show that the reasonable matching of electrode structure parameters can improve the gliding arc guiding ability of the discharge electrode. Comparing the three electrode shapes, it was found that the triangular electrode had the best gliding arc guiding ability, and it had the potential to further increase the plasma size with the increase in the electrode size. The discharge distance and electrode opening angle had a significant impact on the gliding arc guiding ability of the discharge electrode. When the discharge distance was 15 mm and the electrode opening angle was 76°, the structure parameters of the plasma seed treatment electrode were matched with each other, and the best processing capacity was achieved. After 10 s of gliding arc plasma treatment with the optimized triangular electrode structure, the seed germination rate and germination index of Leymus chinensis ((Trin.) Tzvel) increased by 33.3% and 13.8%. This study provides a theoretical basis for the design and optimization of gliding arc electrode structures and serves as a reference for the research and development of plasma generators for continuous seed treatment at atmospheric pressure. [ABSTRACT FROM AUTHOR]

The abiotic synthesis of peptides, widely regarded as one of the key chemical reactions on the prebiotic Earth, is thermodynamically constrained in solution. Herein, a simulation of the lightning phenomenon on the sea surface using bubble bursting and arc plasma under ambient conditions enables dipeptide formation of six amino acids with conversion ratios ranging from 2.6 % to 25.5 %. Additionally, we observed the formation of biologically active tripeptides and investigated the stereoselectivity of the dipeptide formation reaction. By utilizing a mixture of 20 amino acids in the reaction, 102 possible dipeptides were generated. These results establish experimental constructions to mimic achievable prebiotic conditions and provide a credible pathway for endogenous biopolymer synthesis on prebiotic Earth. [ABSTRACT FROM AUTHOR]

At present, research on arc magnetic confinement predominantly focuses on the influence of external magnetic fields (EMF) on traditional free-welding arc. However, studies on magnetic re-confinement of plasma cut arc constrained by mechanical structures remain limited. This study establishes a three-dimensional (3D) electromagnetic model for the confinement device and designs a 3D plasma cutting arc model based on magneto-hydrodynamics. Through a combined simulation approach using Maxwell and ANSYS, we extensively investigated the distribution of the longitudinal magnetic field (LMF) and emphasized its impact on the characteristics of the plasma cutting arc. Within the range of 0 ~ 200 mT, simulations were conducted to analyze the temperature, velocity field, flow field, and arc pressure distribution of the plasma cutting arc under varying LMF intensity. The results indicate that the application of LMF can significantly enhance the current density, temperature, and straightness of the plasma cutting arc, thereby improving the cutting performance. These findings provide valuable theoretical insight for optimizing magnetic re-confinement plasma arc cutting device and process in practical engineering applications. [ABSTRACT FROM AUTHOR]

In gas–metal arc welding (GMAW), the welding quality is influenced by various factors, including the welding conditions and external environment. Achieving a high welding quality requires careful observation and control. Welding monitoring is crucial for validating a planned welding process and assessing its quality. This study introduces a vision system for the online acquisition of clear molten pool images. It uses a small camera equipped with a complementary metal-oxide-semiconductor sensor during GMAW, as well as a method for constructing this system. The proposed vision system does not require triggering using devices such as field-programmable gate arrays, facilitating lower costs and online quality monitoring under various welding conditions during mild-steel GMAW. Accurate measurement of radiation from the weld is essential for clear observation of the molten pool during welding, emphasizing the importance of selecting an optical system with appropriate lenses and filters. In addition, appropriate digital camera parameters must be set for monitoring. High-quality images were successfully captured using the proposed method, and the image quality was evaluated using the blind/referenceless image spatial quality evaluator algorithm. [ABSTRACT FROM AUTHOR]

Precisely assessing plasma parameters holds paramount importance in investigating the arc extinguishing mechanism of semi-sealed splitter plate DC circuit breakers, refining the configuration of splitter plates, and optimizing the overall structural design of circuit breakers. Based on the principle of the Langmuir probe, a double probe diagnostic method is proposed to investigate the air arc plasma in the opening process of a DC circuit breaker. The diagnostic circuit of the probes is designed, and three sets of double probes are arranged to trace the evolution of the plasma density during the opening process. The research reveals that the plasma center density, measured by the diagnostic system during the opening process of the DC circuit breaker, is about 1022 m−3–1023 m−3. This density is compared with the diagnostic results obtained by other methods, confirming the accuracy of the Langmuir double probe for plasma measurements in the DC circuit breaker. The study also revealed an exponential decay behavior of electron density along the radial direction of the arc. A mathematical model was employed to describe this phenomenon, establishing a relationship between the distribution of electron density and arc current. [ABSTRACT FROM AUTHOR]

Ammonia (NH3) production is of global concern for today's food supply security and as future energy vector. Plasma technology can add to supply‐chain resilience of fertilizer production and improve the environmental profile using renewable energy; allowing distributed NH3 production. With the objective to provide process intensification of small‐capacity reactors for local supply, a novel micropyramid‐disk plasma reactor operated in micro‐arc mode was developed. NH3 was synthesized from N2, nitrogen, and H2, hydrogen over Ru/MCM‐41 catalyst at atmospheric pressure. The microplasma brings plasma and catalyst surface close together and intensifies the electric field. The arc plasma elevates temperature, 'nonthermal', releasing high‐energy free electrons, known to be effective in converting low‐reactive molecules. The study demonstrates that microplasma, with reduced electrode‐to‐electrode dimensions and a microstructured reaction environment, enhances the performance of the NH3 synthesis and opens novel process windows. This is detailed on the impact of feed ratio (N2/H2), applied voltage, frequency, electrode gap, and the flow distribution by which the gas is fed in. Optical emission spectroscopy (OES) was used to identify vibrationally and other excited species generated by the microplasma and confirms the catalyst is in symbiosis with the radicals. [ABSTRACT FROM AUTHOR]

CuO nanoparticles obtained in a low-pressure arc discharge plasma followed by annealing in an oxygen atmosphere at 500°C were studied by X-ray diffraction and transmission electron microscopy. The formation of irregularly shaped nanoparticles in the size range of 5–30 nm was found. The Rietveld refinement confirmed the formation of a monoclinic CuO phase with an average crystallite size of ~21 nm. The temperature dependences of the magnetization and permittivity of CuO nanoparticles have been studied. They show antiferromagnetic behavior with a Neel temperature of 230 K and frequency-dependent dispersion behavior in the temperature range of 100–200 K at an external magnetic field induction of 0–1.3 T. The dielectric relaxation mechanism is analyzed and found to follow the Arrhenius behavior. It is shown that hopping conductivity with a variable hop length more accurately describes charge transport in CuO nanoparticles. A magnetodielectric response of about 2.5 was observed at a frequency of 12 kHz at a temperature of 150 K in a magnetic field of 1.3 T. [ABSTRACT FROM AUTHOR]

The effects of cutting speed and current on plasma cut quality were investigated. Regression modeling was used to establish relationship between process parameters and responses. Analysis of variance was performed to determine the significance of independent variables influencing the kerf geometry. The analysis showed that the proposed regression model fits the experimental data fairly well and the selected variables influence kerf length difference and top kerf width substantially. However, while the bottom kerf width was significantly influenced by cutting speed, it was not affected by the current. The analysis results were compared with the experimental data and were found to be in good agreement. The images captured with high-speed camera using appropriate band-pass filter revealed that the plasma flows under the workpiece were affected by the process parameters. The tail length and the direction angle of the plasma flow dictated the shape of the kerf geometry. [ABSTRACT FROM AUTHOR]

This paper utilizes the plasma arc as the heat source to successfully fabricate well-formed thin-walled parts using combined cable wire duplex stainless steel 2209. Microstructure of parts exhibited the favorable two-phase ratio and the absence of σ-phase. It was found that appropriate heat input (1.68 kJ/cm) and cooling rate (5 °C/s) can effectively avoid the precipitation of σ-phase. Furthermore, the properties of the as-deposited samples were comparable to those of the samples heat-treated at 1300 °C, proving that no subsequent heat treatment was required for 2209 stainless steel fabricated by plasma arc additive manufacture. The samples showed excellent properties, in which the ultimate tensile strength and yield strength were improved by about 7% and 24% compared with GB/T4237-2015. The impact toughness meets the requirements of EN10028-7-2016, which is about 35% higher than that of the cold metal transfer samples, and the corrosion resistance is comparable to that of hot rolled 2205. [ABSTRACT FROM AUTHOR]

Plasma-metal inert gas (MIG) hybrid welding enables to join thick steel plates in single pass. However, arc coupling occurring between the plasma and MIG arcs disturbs its heat source characteristics, lowering the welding quality. This arc coupling phenomenon is not yet understood due to the complexity. This study aims to clarify the effect of current waveform of arc on weld bead formation according to the arc coupling in plasma-MIG hybrid welding. The metal transfer characteristics and bottom side weld pool were observed for direct current (DC) and pulse-MIG current waveforms. In addition, Ni element was used for visualizing the transport process of high-temperature molten metal provided by MIG welding within the weld pool. From these results, the effects of differences in MIG arc current waveforms on heat and mass transport processes within the weld pool and also on weld bead formation on the bottom side through changes in the occurrence of arc coupling were discussed. As a result, it was clarified that the droplets after detachment from the wire were transferred to the weld pool surface under the wire tip for DC MIG current, while those were transferred along the wire axis to the weld pool surface behind the keyhole for pulse-MIG current. When the droplet was transferred to the weld pool region with the forward flow such as the pulse-MIG current case, the heat was transported to the bottom side together with the counter-clockwise eddy behind the keyhole, strongly contributing to increasing the penetration depth. In the case of pulse-MIG current, the plasma arc is oscillated due to the arc coupling. According to this oscillation, the accumulation of molten metal behind the keyhole is prevented to suppress the humping bead formation. Consequently, pulse-MIG current was found to be suitable for increasing the penetration depth and suppressing humping bead formation on the bottom side comparing with DC MIG current. [ABSTRACT FROM AUTHOR]

Enhancing lighting intensity while reducing costs is a primary focus. Lamp illumination has been refined by adjusting halide concentrations and pinpointing optimal thermal zones for maximum brightness. Arc discharge, particularly in high-intensity discharge (HID) lamps, plays a pivotal role in lighting technology and system upgrades. This study delves into the plasma processes of the ionization layers near the cathode surface, where we noticed that as the temperature increases, both (Te, ΔA, Øb) increase, also, notice an increase in the voltage barrier as a result of the collision between the electrons that leads to a loss of energy, and this leads to a decrease in the current density as a result of the high energy gap. That is, the value of the work function increases As a result of the increase in the energy of the electrons, which plays a major role in the processes of ionization and excitation, this is reflected in an increase in the temperature of the electron and a decrease in the voltage, especially at a voltage of 20 V, meaning that increasing the voltage difference from 10 to 20 V leads to a significant decrease in the voltage barrier, especially at temperatures greater than (Tw = 3800 K), and this leads to increase the temperature of the electron as a result of increasing the energy of the electrons so, at low temperatures, we notice that the effective work function increases in both cases (10.20) V with the decrease in the potential difference of the plasma layers at the cathode surface proximity, and it has a maximum value at 20 V. The difference in concentration plays a crucial part in increasing the temperature and decreasing the voltage barrier with the difference in the applied voltage. [ABSTRACT FROM AUTHOR]

Among the non-traditional manufacturing processes, electro-thermal based processes are used to machine the difficult to cut materials. Among thermal based unconventional machining processes, laser machining and plasma arc cutting (PAC) are most significant processes that find applications in various industries including aerospace, automotive, shipbuilding, chemical processes equipment manufacturing and fabrication. In this manuscript, the parametric optimization of PAC is extensively reviewed. Bibliometric analysis of PAC was performed using Web of science and Scopus database wherein research publications were analyzed between year of 1961 to 2023. It was observed from the analysis that minimization of energy consumption in thermal based non-conventional machining methods is not extensively studied. Therefore, literature was reviewed to discuss about energy consumption and reduction of energy requirements in laser and PAC machining. [ABSTRACT FROM AUTHOR]

In this paper, undoped and copper-doped ZnO nanoparticles (NPs) were successfully synthesized using a gliding arc discharge (GAD) plasma technique, which is a sustainable, cost-effective, and scalable method. This method offers several advantages over traditional synthesis methods. The synthesized NPs were characterized by various techniques to understand their physicochemical properties. XRD analysis confirmed the presence of characteristic peaks of pure ZnO, while doped samples exhibited additional peaks corresponding to CuO crystal planes, indicating the successful incorporation of Cu into the lattice. As obvious, bare ZnO showed absorption peak at 378 nm corresponding to the band gap of 3.21 eV. The band gap of Cu-doped samples increased systematically, i.e., 3.35 eV for 2% Cu, 3.47 eV for 4% Cu, and 3.66 eV for 6% Cu. SEM images revealed aggregation and increase in particle size with the increasing in Cu concentration. EDAX analysis revealed a decrease in the weight percentage of oxygen and zinc with the increase in Cu concentration, suggesting structural changes within the lattice. Furthermore, the antibacterial activity against Gram-positive and Gram-negative bacteria, antioxidant activity, and photocatalytic activity against three different organic dyes such as Brilliant Cresyl Blue (BCB), Methylene Blue (MB), and Congo Red (CR) was studied. It is found that the photocatalytic activity of ZnO NPs varies with Cu concentration, leading to a decrease in its performance. The antibacterial activity of the NPs was also assessed, with undoped ZnO NPs showing dose-dependent effects against bacteria, while the Cu-doped ZnO NPs exhibited decreased efficacy. Interestingly, Cu doping significantly enhanced the antioxidant activity of the NPs compared to the undoped ZnO. [ABSTRACT FROM AUTHOR]

K-TIG welding is an exceptionally efficient welding technique that enables full penetration with a single pass, without the need for groove preparation or wire filling. Comprehending the distinct arc characteristics of K-TIG welding is crucial for exploring the metallurgical process, heat, and mass transfer, and serves as a guide for design considerations. In this study, 2D numerical models of arc plasma in K-TIG welding were established. The arc characteristics of the keyhole and non-penetrated states were compared, while the influence of welding parameters on arc characteristics was further investigated. Finally, the calculated arc pressure was validated by experiments. Results show that the electric potential gradient in the arc column decreases once the keyhole is formed. Simultaneously, the temperature increases at the center of the anode surface and decreases on both sides away from the arc center. Higher welding currents and smaller tungsten tip angles will lead to an increase in the temperature and velocity of arc plasma. As the tungsten tip height increases, the arc temperature increases on both sides but decreases in the arc center, and the pressure in the inner wall of the keyhole shrinks. [ABSTRACT FROM AUTHOR]

Free-burning arc discharges play important roles in physical processes such as cutting, welding, arc furnaces, and switchgear. Therefore, in this paper, a combination of node-based and edge-based finite-element methods with the finite-volume scheme is developed to investigate the dynamics of these arc discharges. Considering the significant effect of self-induced magnetic fields on the dynamics of the thermal plasma arcs, accurate analysis of these magnetic fields is essential, especially for 3D geometries describing realistic conditions. Accordingly, the edge-based finite-element module is utilized to study the Ampere law in its vector form for estimating the vector potential and the corresponding magnetic field. Furthermore, the current conservation equation is solved using the node-based finite-element technique. The fluid dynamics are also investigated with the well-known finite-volume method. This hybrid model gives more accurate magnetic fields and Lorentz forces. Electromagnetic forces create high-speed streams of thermal plasma and increase the pressure in the near regions of the electrodes. As a result, the pressure and velocity profiles are closer to the predicted results. In addition, the fluid flow changes the temperature distribution in a way that agrees with experimental measurements. [ABSTRACT FROM AUTHOR]

This article investigates the plasma‐enhanced chemical vapor deposition of a‐C:H:SiOx coatings in a non‐self‐sustaining arc discharge plasma with a hot cathode in combination with a low‐frequency (200 kHz) inductively coupled plasma. It is shown that increasing the inductor power from 0 to 600 W leads to a twofold increase in the ion current density on the substrate. An increase in ion bombardment intensity results in a 1.3‐fold reduction in the coating's growth rate due to the resputtering phenomenon, a 1.5‐fold reduction in surface roughness, and an improvement in the mechanical properties of the coatings. The hardness of the coating is increased by 9–11%, the plasticity index by 10–17%, and the resistance to plastic deformation by 32–49%. [ABSTRACT FROM AUTHOR]

The ignition performance of an aeroengine combustion chamber significantly affects the engine's stable operating range. The ignition limit, a crucial factor in determining this performance, has consistently needed enhancement. To improve this and broaden the ignition limit, a kerosene pre-combustion gliding arc plasma jet igniter (KPPJ-Igniter) was developed. This igniter integrates gliding arc discharge, plasma jet ignition, and pre-chamber ignition techniques. Its characteristics were explored using a dual-head fan-shaped combustion chamber test section, where CH* groups produced during ignition were analyzed using the chemical self-luminescence method. The ignition mechanism, limit, and delay time of the KPPJ-Igniter were examined, revealing that increasing the jet flow rate decreases the jet flame length and increases discharge power, with the longest jet flame reaching 69.5 mm. The ignition process involves three stages: ignition transition stage, flame core expansion stage, and stable combustion stage. Two flame cores identified downstream of the igniter and in the combustor dome's recirculation zone significantly influence the combustion process. The KPPJ-Igniter notably extends the ignition limit, especially under low-velocity and low-turbulence conditions. With an inflow velocity of 80 m/s, it can expand the ignition limits by up to 32.6%, increasing the maximum ignition velocity from 80 to 100 m/s. The high ignition performance is attributed to the high-temperature jet flame and its cumulative effects, with the ignition delay time decreasing as fuel supply pressure and inflow velocity increase. [ABSTRACT FROM AUTHOR]