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The target surface to be treated in reality is often not smooth and horizontal and may also be in different tilting angles. The treatment of the tilted dielectric surface by the atmospheric pressure plasma jet (APPJ) undoubtedly increases the complexity of surface modification. Therefore, a two-dimensional fluid model is established to reveal the internal mechanism of the interaction between the He APPJ and the tilted dielectric surface by means of numerical simulation. The distribution of the gas flow in a small angular range (0°, 3°, 5°, 8°, 10°, and 15°) is studied. In addition, the effects of the tilt angle on the jet morphology, discharge dynamic properties, and species distribution of the He APPJ are emphatically discussed. It is found that the jet morphology and parameters are no longer symmetrical under the tilted surface. With the increase in the tilt angle, the enhanced electric field in the upper surface region leads to the increase in the ionization rate and electron density here, and also accelerates the propagation speed of the jet to the dielectric surface in the atmospheric environment. Driven by the electric field force, the jet is closer to the dielectric surface, resulting in a decrease in the thickness of the cathode sheath and an increase in the surface charge density in the area to the right of the central axis. The influence of the gas flow structure leads to the shortening of the jet development distance and a decrease in the jet velocity on the upper surface. N and O also form higher fluxes on the upper surface due to the increase in the electron density. [ABSTRACT FROM AUTHOR]

Helium metastable densities in the COST Reference Microplasma Jet are estimated for a variety of He/N2 admixtures and dissipated powers by applying a collisional-radiative model to absolutely calibrated optical emission spectroscopy measurements. This is accomplished by delineating the excitation mechanisms that result in the N2(C–B) and N 2 + (B–X) emission bands, the latter of which is strongly coupled to the presence of helium metastables. A number of other plasma parameters are established and discussed for each operating condition including the electron energy distribution function, reduced electric field, rate constants, and electron density. With these parameters, the reaction rates for the primary ionization pathways are also calculated, emphasizing the importance of helium metastables for discharge sustainment. Good agreement with the existing literature is found for most plasma parameters and for helium metastable densities, in particular. A clear [N2] − 1 relationship between the nitrogen concentration and density of helium metastables is demonstrated, as has been identified in previous studies in analogous atmospheric pressure plasma jets. This validates the efficacy of this optical technique for determining helium metastable densities and establishes it as a viable, and in many cases, more accessible alternative to other means of quantifying helium metastables in low-temperature plasmas. [ABSTRACT FROM AUTHOR]

The contribution of atomic nitrogen is fairly possible in plasma-assisted catalytic synthesis of ammonia since it has high adsorption probabilities on solid surfaces. On the other hand, recently, the contribution of vibrational excited molecular nitrogen to ammonia synthesis has been discussed. In this work, we compared the fluxes of atomic nitrogen and vibrational excited molecular nitrogen with the rate of plasma-assisted ammonia synthesis. We employed an atmospheric-pressure nitrogen plasma jet, and the spatial afterglow of the plasma jet and a hydrogen flow irradiated the surface of a ruthenium catalyst. The fluxes of atomic nitrogen and vibrational excited molecular nitrogen were measured by two-photon absorption laser-induced fluorescence spectroscopy and laser Raman scattering, respectively. The synthesis rate of ammonia had a positive correlation with the flux of vibrational excited molecular nitrogen, while the variation of the synthesis rate with the gas flow rate was opposite to the flux of atomic nitrogen. The experimental results indicate the contribution of vibrational excited molecular nitrogen to the synthesis of ammonia using the atmospheric-pressure plasma, where the flux of vibrational excited molecular nitrogen is more than four orders of magnitude higher than that of atomic nitrogen. [ABSTRACT FROM AUTHOR]

We present experimental measurements of the electron temperature and density profiles and analyze the dynamics of a plasma bullet at volumetric concentrations of nitrogen admixture, 0%–3%, in an atmospheric-pressure nanosecond-pulsed argon jet plasma. Time-resolved Thomson scattering measurements taken 2.5 mm from the exit plane reveal that the temporal maximum of electron temperature and density reduced by as much as 55% and 29%, respectively, when mixing only 3% nitrogen to pure argon. These trends were consistent across axial locations from 2.5 to 14 mm from the exit plane for both electron temperature and density at nitrogen admixture plasmas. Moreover, the propagation velocity and length of the plasma bullet decreased by 13% while the radius by 23% at 3%-nitrogen admixture when compared to the pure argon jet case. The analysis suggests that the nitrogen admixture causes electron cooling due to inelastic energy losses, which results in a reduced electron density and propagation velocity due to a decrease in the electron-impact ionization rate. It is therefore inferred that the electron cooling mechanism and reduced density at nitrogen admixture will significantly impact the electron-impact excitation rate coefficient of nitrogen as well as the concentration of the precursor species such as N2(A3Σu+). [ABSTRACT FROM AUTHOR]

The atmospheric pressure pulsed microwave He plasma jet has the advantages of high electron density and abundant active particles, but its shrinking on the discharge electrode morphology limits its application range. In order to modulate a He plasma jet with a longer plume and study its ionization development characteristics, we constructed a dual-channel pulsed microwave coaxial discharge device. He and air were, respectively, injected into the inner and outer gas channels of the resonator to generate a double-layer atmospheric pressure microwave plasma jet with a longer plume. It is observed that the bifurcation of the stratified plasma jet will occur by changing the gas flow. The ionization development of plasma jet was observed by using enhanced charge-coupled device and microwave Rayleigh scattering apparatus measured the space-time evolution of plasma and observed the three times ionization enhancement process of plasma jet development. The spectral lines of the active products associated with Penning ionization were observed by using a fiber optic spectrometer. A fluid model was constructed to simulate and analyze that under the condition of sufficient He flow rate (He flow rate is above 0.6 slm), there will be sufficient and stable He mole fraction (64%) at the stratification of the plasma jet. The experimental and simulation results show that the jet profile of the microwave He plasma is related to the inlet structure of the discharger and He flow rate. Stratified intake structure can produce stratified He plasma jet, and the unique appearance of bifurcation of jet can be produced by changing the flow rate of He. In the bifurcation process of the plasma jet, the product of Penning ionization inhibits the development of the main branch of the plasma jet, and the secondary electron avalanche of the local electric field promotes the formation of the branch of the plasma jet and is accompanied by the enhancement of the second ionization. The ionization mechanism of microwave He plasma is the resonance excitation of local enhanced electric field, the advance of ionizing waves, and the interaction between the spatially distributed active particles. [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]

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

Low-temperature plasma (LTP) jets are Food and Drug Administration (FDA)-approved medical devices to remove cancerous tissue and aid in wound healing. However, reports on their reaction with proteins are conflicting, ranging from fragmentation, oxidation, aggregation, or a combination thereof. In this study we bridge the gap between plasma-treatment of short peptides to proteins at physiologically relevant concentrations. The LTP in this study is based on a helium dielectric barrier discharge that forms a plasma-jet, which is directed at the solution without direct contact with the plasma, and results in the formation of reactive oxygen species (ROS) OH• and O2•− in solution. The longer the solution is treated, the more solution-phase ROS form. Treating peptide- and protein-containing solutions leads to extensive oxidation. The ROS led to the same oxidative modifications for peptide M with increasing chain length (9, 18, 37, 76 amino acids), which could be identified with high-resolution mass spectrometry. Oxidized species M + x O led to conformational changes such as compaction and elongation, while the unmodified peptide M remained unaltered, as found by ion mobility spectrometry and size exclusion chromatography. For proteins at high concentration, insoluble aggregates formed and could be identified by UV/V is light scattering and atomic force microscopy. The formation of aggregates is dependent on the amino acid chain length, the peptide concentration, and the time for aggregate formation. These findings highlight the importance of both peptide chain length and concentration in determining the fate of peptides following the exposure to LTP, while also offering valuable insights for the field of plasma medicine. [ABSTRACT FROM AUTHOR]

We present a new food processing method to increase the content of polyphenols, which are a type of health-promoting food component, in harvested onions using atmospheric-pressure low-temperature plasma technologies. Harvested onions were locally irradiated for different times with a low-temperature air plasma jet generated near atmospheric pressure and stored in the dark for various periods. The plasma-irradiated area was 7 mm2. The plasma irradiation was performed without removing the onion peel. After storage following plasma irradiation, the onion was peeled and cut into the outer, middle, and inner parts, analysing polyphenol content at each edible onion part, namely the bulb. The polyphenol content in the onions irradiated for 30 min and stored for 3 d increased over that of unirradiated onions stored for the same period. This increase occurred regardless of the bulb parts. Neither the plasma-irradiated onions without storage nor the air gas-irradiated onions without air plasma irradiation exhibited a higher polyphenol content. In particular, quercetin aglycone, quercetin 4′-O-glucoside, quercetin 3-O-glucoside, and quercetin 3,4′-O-glucoside were increased in the polyphenol content, contributing to an increase in the antioxidative activity. NO3− and NO2− were introduced into water under an onion peel by air plasma irradiation for 30 min and decreased after 3 d of storage but remained. However, no H2O2 was introduced. The plasma-introduced NO3− was distributed throughout the onion owing to the plasmodesmata serving as channels for cell-to-cell transports of molecules. These results suggest that the increased polyphenol content originates from the transcriptional factors acting in stress responses to the plasma-introduced NO3− and NO2−, not the electric field-induced electroporation, in onion cells. The present study provides valuable insights into interactions between low-temperature air plasma jets and onion cells. [ABSTRACT FROM AUTHOR]

A new design of plasma-assisted injector to ignite or stabilize combustion is presented. This design is intended to produce discharges that penetrate the combustion chamber instead of staying at the wall. This plasma-assisted injector, simple and robust, allows compact designs for a weakly intrusive implementation in engines, and is compatible with either air or fuel, depending on the process or application. A prototype was manufactured, implemented and tested with quasi-DC discharges on the LAPCAT2 Dual Mode Ramjet combustor at LAERTE facility in ONERA. Combustion tests showed earlier ignition and increased pressure when the plasma was turned on with a measured plasma power of 1.4 kW. • Presentation of the design and principle of a new plasma assisted injector. • Demonstration of its ability to generate discharges penetrating the flow. • Characterization of the discharge dynamics and its interaction with the gas flow. • Comparison of the discharge behavior in hydrogen vs air. • Ability of the plasma assistance to enhance supersonic combustion. [ABSTRACT FROM AUTHOR]

This study explores the use of air-fed atmospheric pressure plasma jets (APPJs) as a pre-joining treatment for 3D carbon fiber-reinforced carbon matrix composites (C/C) with the aim of both creating a textured surface that resembles a brush structure and improving the joint strength. The effects of various treatment time lengths on the mass loss, etching depth, and surface texture were investigated using SEM and confocal microscopy. An optimal process time of 30 s was selected, while keeping the other process parameters fixed (air flow of 1750 l/h and nozzle-sample distance of 5 mm). Wetting tests were conducted at 1000 °C, on both untreated and pre-treated C/C surfaces by means of liquid TiCuNi brazing alloy, and low contact angles of about 20° were measured. C/C–TiCuNi–C/C and C/C–TiCuNi–Cu joints were then produced, and their interfacial reactivity was evaluated. The apparent shear strength measured for the APPJ-treated C/C–Cu joints was 140 % higher than the value recorded for the untreated joints, thus confirming the effectiveness of the treatment. Even though a further investigation is needed in which an optimization of the process parameters should be included, this preliminary study has revealed the viability of APPJ as a promising technique to enhance the bonding of C/C composites in dissimilar assemblies and to improve the joint quality. [ABSTRACT FROM AUTHOR]

Wound healing is a dynamic and intricate biological process crucial for tissue repair and regeneration. This study explores the potential therapeutic impact of non-thermal plasma generated by a hand-held cold atmospheric pressure plasma jet (C-APPJ) source on fibroblast cells (NIH/3T3) in vitro. The sequential phases of wound healing—inflammation, cell proliferation, and tissue remodelling, were assessed in the context of cell migration and oxidative stress dynamics. Typically, plasma generates a mixture of several reactive oxygen/nitrogen (ROS/RNS) species. The present study investigates the safety and efficacy of C-APPJ under distinct operating conditions (argon (GI) and argon + nitrogen (GII)) and exposure times (1 min and 3 min). Cell viability assays confirmed the non-cytotoxic nature of the cold plasma conditioned medium. The levels of ROS/RNS and malondialdehyde (biomarker of oxidative stress) in the plasma-treated samples remained comparable with the control fibroblast cells grown in normal media, suggesting the favourable modulation of ROS by the cellular antioxidant mechanisms. Accelerated wound-closure rates from 6th hour to 24th hour in all the treated groups ranged from 38.76% to 45.66%, when compared to 34.25% in the control cells. Substantial cell migration leading to 51.59% of wound closure was recorded in the argon + nitrogen (GII) group exposed for 3 min. Taken together, the potential of cold plasma to effectively heal wounds without causing prolonged oxidative stress and chronic inflammation is implicated. These outcomes suggest scope for clinical application of C-APPJ as safe and cost-effective treatment of wounds (ulcers, burns, diabetic foot) and wound disinfection. [ABSTRACT FROM AUTHOR]

The reactive species-independent nature of cold plasma's electric field is pivotal in biomedical applications. This work proposes to connect the plasma fluid model and the asymptotic Smoluchowski model for electroporation, providing a unified framework to investigate the evolution of the electric field in the biological substrate and the multi-stage electroporation response of the human cell. Two common substrates with distinct dielectric properties, namely, the cultivation medium and epidermis, are selected to report three stages of ionization wave (IW)–substrate interaction. The three-stage streamer discharge dynamics (restrike, axial-radial transition, and radial expansion of IW) induce three-stage cell electroporation dynamics (slow charging, fast charging, and electroporation), though the two processes are asynchronous. Specifically, the inner membrane covered the cell nucleus with ultra-short charging time that undergoes only the first two discharge stages in both substrates. Whether the cell membrane is exposed to the third stage of discharge depends on the permittivity of the substrate. The asynchrony can be attributed to the difference in the charging time of the cell membranes and substrates affected by the substrate permittivity. The presented model can provide quantitative insights into the cell electroporation induced by the IW–substrate interaction and theoretical guidance for plasma biomedical applications. [ABSTRACT FROM AUTHOR]

This research is devoted to the fabrication of zinc selenide nanostructures using the pulsed laser deposition (PLD) technique in a vacuum under a pressure of 2. 5 × 1 0 − 2 mbar. The structure and structural properties were studied, as it was observed that it had polycrystalline structures and showed peaks for zinc and selenium and peaks belonging to the compound zinc selenide. As for the morphological characteristics of the nanostructures, the structures showed the nature of the surface and the roughness to identify its surface properties. Photocatalysis was carried out using several techniques (visible light, ultraviolet radiation and cold plasma), where a plasma jet system produced under normal atmospheric pressure was used in the treatment, with an exposure time of 4 min and an argon gas flow rate of 3 l/min. The hydrophilic properties were studied to apply these compositions in the self-cleaning process and photocatalytic activity. The results show that the ZnSe nanostructures have high wettability under UV light which has been shown to have excellent catalysis in the UV region, making its application as a self-cleaning material an attractive option. [ABSTRACT FROM AUTHOR]

When solving the problems of dynamics in space of EP's plasma jets, it is necessary to take into account the influence of the Earth's magnetic field on the formation of a plasma stream (EP-electric propulsion). It is shown that under the influence of a geomagnetic field, plasma jets acquire specific three—dimensional shapes at some distance from the source, biconvex plasma petals—"corsunoids." The strength of such influence is determined by a parameter of electromagnetic interaction—the Ampere parameter equal to a scale of the ratio of a transverse electromagnetic force to a pressure gradient. [ABSTRACT FROM AUTHOR]

Atmospheric pressure plasma jets (APPJs) have attracted significant attention due to their ability to generate plasma without vacuum systems, facilitating their use in small areas of plasma processing applications across various fields, including medicine, surface treatment, and agriculture. In this study, we investigate the interaction between two helium plasma jets, focusing on the effects of varying flow rate, voltage, and directional angle. By examining both in-phase and out-of-phase configurations, this research aims to elucidate the fundamental mechanisms of plasma plume merging, which has critical implications for optimizing plasma-based material processing systems. We demonstrate that while increasing voltage and flow rate for the in-phase condition leads to an extended plasma plume length, the plumes do not merge, maintaining a minimal gap. Conversely, plasma plume merging is observed for the out-of-phase condition, facilitated by forming a channel between the jets. This study further explores the impact of these merging phenomena on plasma chemistry through optical emission spectroscopy, revealing substantial differences in the emission intensities of OH, the second positive system of N 2 , and the first negative system of N 2 + . These findings offer valuable insights into controlling plasma jet interactions for enhanced efficiency in plasma-assisted processes, particularly where plume merging can be leveraged to improve the treatment area and intensity. [ABSTRACT FROM AUTHOR]

Plasma jet printing, which does not require preprocessing and postprocessing, is a promising technology for manufacturing flexible electronics. The conductive properties should be confirmed to ensure the performance of the flexible electronics. In this study, the conductive properties and control mechanism of plasma jet‐printed silver patterns were investigated. Analyses show that high‐energy particles in the plasma decomposed organic solvents and induced the interconnection between silver nanoparticles. The plasma jet‐printed silver patterns had high uniformity in vertical spatial distribution. The dense packing of the silver patterns was achieved by increasing the number of printed layers, reducing the print speed, and increasing the focusing ratio. Oxidation of the silver nanoparticles was reduced and the conductivity was improved by increasing the focusing ratio. [ABSTRACT FROM AUTHOR]

Spurred by global COVID‐19, work in recent years has demonstrated that various devices based on technology generating cold plasma are capable of reducing the infectivity of virus particles. There is great potential in this approach, which is, however, hampered by the ability of most cold plasma science laboratories to test for antiviral effects of their individual plasma sources in sophisticated mammalian cell test systems. To this end, we developed a quick, simple, and fast assay system based on bacteriophages and their ability to lyse bacterial hosts, which can be monitored in readily available microplate readers. We successfully demonstrated the principal ability of this approach using two types of plasma jets, different microplate readers, and two different bacteriophage strains. [ABSTRACT FROM AUTHOR]

In this article, a compact and portable microwave atmospheric pressure plasma jet (MW‐APPJ) generator based on a coaxial transmission line resonator (CTLR) was proposed. Based on the electromagnetic simulations, the jet generator was designed as a tapered inner conductor structure that ensures plasma generation at low power. A self‐igniting argon (Ar) plasma jet of 10 mm length was generated at an input power of ~20 W and maintained at 2 W. Thanks to the high efficiency of the CTLR structure, plasmas of mixed reactive gases were also realized. Intrinsic plasma parameters and active species were determined using optical emission spectroscopy. Furthermore, the MW‐APPJ device was used to modify the polytetrafluoroethylene surface, and improvement of hydrophilicity was achieved without thermal damage. [ABSTRACT FROM AUTHOR]

The modulation of surface properties of Ti3C2Tx plays a crucial role in its diverse applications across various fields. However, a straightforward and reliable technique for controlling its surface functional groups remains elusive. In this study, we achieved controlled modification of Ti3C2Tx surface functional groups using atmospheric‐pressure cold plasma. We evaluated the plasma generation characteristics and found that the gas parameters could influence the discharge power and lead to different gas temperatures with the same voltage. Spectral analysis confirmed the presence of numerous reactive species in the plasma, facilitating the breaking and recombination of chemical bonds of functional groups on the Ti3C2Tx surface. The interaction between the plasma jet and Ti3C2Tx film revealed that the semiconductor properties of the Ti3C2Tx film limit the plasma diffusion area, while N2 doping and increased gas flow rates respectively reduce and enlarge the coverage area of cold plasma. A brief one‐minute cold plasma treatment induced a slight etching effect on the Ti3C2Tx film surface, effectively altering the ‐O and ‐F functional groups. However, it is noteworthy that excessive cold plasma treatment in the air may result in partial oxidation of Ti3C2Tx, necessitating the use of custom gas environments in further applications. This research provides valuable insights into surface modification techniques for Ti3C2Tx with potential implications in a wide range of applications. [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]

Atmospheric plasma jets generated from air or nitrogen using commercial sources with relatively high energy densities are commonly used for industrial applications related to surface treatments, especially to increase the wettability of polymers or to deposit thin films. The heat fluxes to which the substrates are subjected are typically in the order of 100–300 W/cm2, depending on the treatment conditions. The temperature rise in the treated polymer substrates can have critical consequences, such as a change in the surface crystallinity or even the surface degradation of the materials. In this work, we report the phase transitions of two semicrystalline industrial-grade polymer resins reinforced with glass fibers, namely polyphenylene sulfide (PPS) and polyphthalamide (PPA), subjected to plasma treatments, as well as the modeling of the associated heat transfer phenomena using COMSOL Multiphysics. Depending on the treatment time, the surface of PPS becomes more amorphous, while PPA becomes more crystalline. These results show that the thermal history of the materials must be considered when implementing surface engineering by this type of plasma discharge. [ABSTRACT FROM AUTHOR]

The Solid-State Linear Transformer Driver (SSLTD) is a nanosecond pulse power source characterized by its fast rise time and adjustable output waveform. It can generate uniform and stable atmospheric plasma jets, which is suitable for material surface modification. In this study, a 15-stage SSLTD was designed and assembled, which can produce a stable nanosecond pulse voltage up to 15 times the amplitude of the charging voltage at high frequencies, with a rise time of approximately 10 ns. This device can be used to generate stable atmospheric pressure Ar plasma jets with an electron density in the range of 1015~1016 cm−3 and gas temperatures close to room temperature. After the modification treatment by the plasma jets, the content of the C=O groups on the surface of the epoxy resin significantly increased in the wavelength range of 1720~1740 cm−1, and its flashover resistance was noticeably enhanced. The optimal comprehensive modification effect was achieved at a charging voltage of 600 V, pulse width of 50 ns, and pulse frequency in the range of 800~1000 Hz. [ABSTRACT FROM AUTHOR]

In this work, zinc nanoparticles were prepared using the low-temperature plasma method at different times 3 min, 5 min, 7 min, 9 min, where the initial reactions of zinc lead to the formation of nanoparticles. The metal interacts with the ionized plasma under different conditions and may turn into an oxide such as exposing the sample to air and raising the temperature of the solution a few degrees as a result of high voltage and within a certain range. The atmospheric pressure plasma system acts as the cathode, while the zinc metal strip acts as the anode. A series of techniques were used, including the use of X-ray diffraction (XRD), ultraviolet-visible spectroscopy and scanning electron microscopy (FESEM). The X-ray diffraction results showed that the samples have polycrystalline structures with hexagonal and cubic structures with a time difference, and the X-ray diffraction results showed the conversion of zinc particles into zinc oxides. FESEM images reveal particle size and shape. The ZnO nanoparticles prepared by the mentioned method seem to form different nanoshapes such as starfish and mushroom nanoparticles. The UV-visible results showed that the samples had an energy gap of about 3.4 eV at a time of 3 min, and this value decreases with increasing reaction time. The appearance of zinc oxides increases gradually with the passage of time. These results provide credibility for the fabrication of ZnO nanostructures for use in future gas sensing applications, despite the inhomogeneity of particle size among ZnO particles, the sensor was also fabricated to detect nitrogen gas (NH3) with different concentrations (17.25 ppm, 46.38 ppm, 78.58 ppm). at room temperature. The ZnO sample showed the highest sensitivity (88.1%) at 7 min. The sensitivity showed different results and increased with reaction time and gas concentration. However, response and recovery time are moderate and decrease as reaction time increases. [ABSTRACT FROM AUTHOR]

Direct bonding of a TP340 titanium to PEEK by hot pressing via pre-treatment of non-thermal atmospheric pressure plasma jet has been demonstrated. The plasma irradiation effect on the bonding surface on the bond strength after hot pressing was investigated. The tensile shear strength of TP340-PEEK joined by hot pressing after plasma pre-treatment was measured by comparing specimens bonded using conventional hot pressing and those bonded using adhesives. The plasma treatment to the TP340 side resulted in the formation of TiO2, which is chemically fed to oxide formation due to the irradiation of oxygen radicals generated by the plasma, resulting in a bond strength of less than 1 MPa, similar to the bond strength of the untreated specimens. The plasma irradiation effect on the PEEK side on the bond strength of TP340-PEEK bonded samples was also investigated. The bonding strength was increased by plasma irradiation to PEEK. As the plasma irradiation time was increased, the bonding strength gradually increased to 9.2 MPa, which is about 19 times higher than the bonding strength without plasma irradiation. These results suggest that oxygen radicals in the atmospheric pressure RF plasma jet produced oxygen-containing surface functional groups on the PEEK surface, which increased the strength of the TP340-PEEK direct joining. [ABSTRACT FROM AUTHOR]

Conducting metal interconnections are essential to link electronic components or multiple circuits for electronic device fabrication. Scalable, rapid, and sustainable methods for printing adherent metal interconnections on dielectric materials are lacking, which stifles the development of new electronic consumer devices. Here a breakthrough single‐step and rapid process to deposit highly conducting metal tracks is introduced, using an atmospheric pressure plasma jet. The deposition process used a rudimentary aqueous solution of metal salts as ink, that was introduced as a mist into a helium plasma gas. The metal salt was reduced and deposited with spatiotemporal control using a plasma jet generated at radio frequency with 15 W power at room temperature and pressure. The conductive metal layers were highly adhesive on glass, ceramics, polymeric materials, even biological surfaces such as plant leaves and animal skin, depostedwith little damage to the substrate. The conductivity of deposited tracks on glass shows 50.8 ± 8.6% and 5.2 ± 1.6% of bulk silver and copper metal conductivity respectively. [ABSTRACT FROM AUTHOR]

For satellites in Very Low Earth Orbit (VLEO) or the upper atmosphere, Air-Breathing Electric Propulsion (ABEP) can be used to counteract the drag effects of the atmosphere or provide attitude control without the need for onboard propellant storage. The Dense Plasma Focus (DPF) inspired the design of an ABEP Pulsed Plasma Thruster (TAMU PPT) which takes advantage of the simplicity, scalability, and high energy density of the DPF. This work details the design and testing of a PPT for use on satellites in the upper atmosphere. Testing was conducted at a variety of pressures and pulsing energies to determine which conditions provide maximum thrust and thrust to power ratios (TPR). It was found through single pulse experiments that a pressure of 6.3 hPa (corresponding to an altitude of about 35 km) and an energy per pulse of 9 J yield a TPR of 21 mN/kW. High frequency operation at 20 Hz in similar conditions showed a TPR of up to 28 mN/kW with a corresponding thrust of 4.8 mN. High speed imaging of the plasma plume found plasma velocities in excess of 2 km/s and identified metal ejecta with velocities up to 350 m/s. The pinching phenomenon associated with a DPF was also observed and a plasma jet velocity up to 50 km/s was recorded. The TPR of the TAMU PPT demonstrated in this work is comparable to that of other ABEP thrusters, however the TAMU PPT has an advantage when comparing thrust density. The TAMU PPT has a thrust density between 4.8 and 19 mN/cm2 while other ABEP thrusters have thrust densities between 0.019 and 0.36 mN/cm2. [ABSTRACT FROM AUTHOR]

Aims This study aims to assess the potential bacterial inactivation pathway triggered by argon (Ar) cold atmospheric pressure plasma jet (CAPJ) discharge using spectroscopic and imaging techniques. Methods and results Electrical and reactive species of the Ar CAPJ discharge was characterized. The chemical composition and morphology of bacteria pre- and post-CAPJ exposure were assessed using Fourier transform infrared (FTIR), Raman micro-spectroscopy, and transmission electron microscopy (TEM). A greater than 6 log reduction of Escherichia coli and Staphylococcus aureus was achieved within 60 and 120 s of CAPJ exposure, respectively. Extremely low D- values (<20 s) were recorded for both the isolates. The alterations in the FTIR spectra and Raman micro-spectra signals of post-CAPJ exposed bacteria revealed the degree of destruction at the molecular level, such as lipid peroxidation, protein oxidation, bond breakages, etc. Further, TEM images of exposed bacteria indicated the incurred damages on cell morphology by CAPJ reactive species. Also, the inactivation process varied for both isolates, as evidenced by the correlation between the inactivation curve and FTIR spectra. It was observed that the identified gas-phase reactive species, such as Ar I, O I, OH•, NO+, OH+, NO2−, NO3−, etc. played a significant role in bacterial inactivation. Conclusions This study clearly demonstrated the effect of CAPJ exposure on bacterial cell morphology and molecular composition, illuminating potential bacterial inactivation mechanisms. [ABSTRACT FROM AUTHOR]

Plasma ignition and combustion enhancement is a promising technology in applications of engines, industrial burners, pollutant emissions controls, etc. A new repetitive electrothermal plasma jet ignition system based on ablated capillary discharge under atmospheric pressure is presented in this paper. It consists of a capillary discharge module, a pulse current circuit, a pulse voltage circuit, a current release unit, an LC series resonant circuit, and a control system. The effects of the energy storage capacitor's voltage and resistance in the current release unit on the electrical parameters are investigated. Increasing the capacitor voltage helps to shorten the discharge delay and increase the energy deposition efficiency in the main discharge process. The increase of the resistance in the current release unit leads to a longer discharge delay and higher energy deposition efficiency in the main discharge process. Balanced parameters between the delay of discharge in 66 µs and the energy deposition efficiency in 84% are achieved through optimization, with a peak radiative heat flux of 23 MW m−2 and a maximum jet length of 17 cm. Repetitive capillary discharge at 20 Hz under atmospheric pressure is achieved with the dispersion of energy storage capacitor charging voltage and energy deposition efficiency of 0.3% and 9.6%, respectively. Simplified circuit topology and control logic contribute to the miniaturization of the ignition system. [ABSTRACT FROM AUTHOR]

A two-dimensional axisymmetric fluid model was established to investigate the dynamic behavior of pre-ionized pulsed-direct-current helium plasma jets at atmospheric pressure. Our simulation results show that, at a relatively low pre-ionization level, the electron number density is reduced and the streamer propagation is decelerated before the plasma jet is ejected from the tube, which is attributed to the inhibitory effect of a recombination process between the positive ions in the streamer and the seed electrons near the anode. As the pre-ionization reaches a relatively high level, the electron number density is larger than that without pre-ionization before the plasma jet is ejected from the tube, which originates from the promotion effect of decreased breakdown voltage. These two competing mechanisms jointly dominate the dynamic behavior of gas discharge in the presence of pre-ionization. After the plasma jet is ejected from the tube, the enhanced discharge power is responsible for the strengthened electric field in the streamer head, augmented total ionization rate, accelerated streamer propagation, and increased number density of electrons and active species, whatever the pre-ionization density is. With the increase in pre-ionization density, the plasma jet length, streamer propagation speed, discharge power, and discharge energy exhibit the initial increase and subsequent decrease variation trend. The optimal enhancement effect is obtained at the pre-ionization density of 6 × 1012 m−3, with the plasma jet lengthened by 28.4% and the energy deposition efficiency enhanced by 28.1%. [ABSTRACT FROM AUTHOR]

Large-scale plasma plumes downstream of plasma jets are in urgent need from a practical viewpoint. In this Letter, an argon plasma jet with floating electrodes is proposed to produce a large-scale planar plume array. Results indicate that with increasing peak voltage (Vp), the planar plume array elongates gradually and scales up in the lateral direction to an optimal value of 90.0 mm. There is only one discharge pulse per voltage half cycle, whose intensity and duration increase with increasing Vp. Moreover, there is a time lag between the initiations of individual plumes. Fast photography reveals that the planar plume array originates from the repeated process of some micro-discharge filaments stretching along the argon stream. By optical emission spectroscopy, the spatial distribution of plasma parameters is obtained, such as electron density, electron temperature, and gas temperature. At last, the planar plume array is employed to test the surface modification of polyethylene terephthalate, for which a uniform modification has been realized with a scan velocity of 1.0 cm/min. These results are of great significance for the development of large-scale atmospheric pressure plasma sources. [ABSTRACT FROM AUTHOR]

Cold physical plasma, a partially ionized gas, has been shown to be effective in treating chronic wounds and cancer. However, there is limited research on plasma exposure of leukemia cell lines, such as chronic lymphocytic leukemia (CLL) and cytotoxic CD8+ T cells. To investigate the potential proimmunogenic effects of plasma‐derived reactive oxygen species, cytotoxic T cells were isolated from CLL patients and healthy volunteers. Extensive cold plasma treatment reduced T‐cell metabolic activity and viability in both diseased and healthy groups. Plasma treatment of cocultures, but not CD8+ T‐cell monocultures, spurred cytotoxic T‐cell proliferation, possibly due to plasma‐enhanced CLL antigen display and plasma‐mediated modulation of immunoregulatory surface molecules. Further studies are needed to understand the mechanisms and clinical relevance of these findings. [ABSTRACT FROM AUTHOR]

Pulse opposing plasma synthetic jets (OPSJs) have potential for reducing the drag coefficient of hypersonic airfoils. This paper numerically investigated the effects and flow control mechanisms of a continuous nanosecond pulse OPSJ on the aerodynamic performance of a hypersonic airfoil. The results indicate that a continuous-pulse OPSJ reduces the airfoil drag coefficient by generating diffracted waves to shift the leading-edge shock wave. However, the flow control effectiveness of a pulse OPSJ decreases with the increase of the pulse sequence. The time-averaged lift-to-drag ratio of the airfoil decreased rapidly from 1.11 for the first pulse sequence to 0.94 for the third pulse sequence, followed by a gradual decrease. The thermal accumulation within the cavity triggers a blocking effect, impeding the heat exchange between the cavity and external fluid. This is the primary factor leading to the decreasing flow control effectiveness of continuous-pulse OPSJs. Furthermore, the results suggest that enhancing the mixing effect within the cavity can improve heat transfer between the cavity and the external flow, suppress thermal accumulation, and improve the flow control capability of continuous-pulse OPSJs in hypersonic flows. [ABSTRACT FROM AUTHOR]

Attention has recently been given to finding alternative and sustainable raw material sources for wood and metal adhesives, such as polyvinyl alcohol (PVA), corn starch (CS), arabic gum (AG), and dextrins (D). Modifying polymer dispersion using unique substances, such as modifying reactive elastomer liquid (EL) using PVA, CS, AG, or D results in sufficiently moisture-resistant adhesive joins. In the present study, the physical characteristics of EL/blended with the natural polymers PVA, CS, AG, and D, based on high-density fiberboard (HDF) wood and aluminum (Al) adhesives and coatings, were investigated and compared to those of pure EL. The EL was blended with PVA, CS, AG, or D at a ratio of 60/40 (w/w) to form EL/blends. The chemical structures, surface and interface morphology, adhesion strengths (including shear strength and pull-off strength), surface roughness, wettings, color intensity, and thermal insulation of the prepared EL and EL/blends were investigated. A scanning electron microscopy (SEM) investigation confirmed filler dispersion and adhesion between the blends, and coated HDF wood, or Al. The developed EL/AG blend had a pull-off strength of 144±5 and 102±3 MPa and a shear strength of 771±11, and 52±3 N with HDF wood and Al substrate, respectively. The EL/PVA blend had a maximum surface roughness value 4.57 μm, and its average water contact angle (WCA) was 85.6°. A plasma jet was used to treat the surface roughness and hence the wettability of the pure EL and the EL/blends, for example, plasma treatment decreased the roughness of the EL/AG blend from 4.36 to 3.28 μm. WCA, and hence wettability, was also significantly influenced by plasma treatment, for example, plasma treatment decreased the WCA of the pure EL from 71.7±0.4° to 30.7±0.7°. The lightness value of the EL/blends was less than that of the pure EL, indicating that (the color adhesives have darkened). Similarly, the yellowness-blueness and redness-greenness values of the EL/blends were greater than those of the pure EL, (rendering the blended adhesives more reddish and bluish). The EL/AG blend was found to have a minimum thermal conductivity (of 0.27 W/m.K), indicating maximum insulation. [ABSTRACT FROM AUTHOR]

There is a currently a lack of large-area plasma sterilization devices that can intelligently identify the shape of a wound for automatic sterilization. For this reason, in this work, a plasma sterilization device with wound-edge recognition was developed using a field-programmable gate array (FPGA) and a high-performance image-processing platform to realize intelligent and precise sterilization of wounds. SOLIDWORKS was used to design the mechanical structure of the device, and it was manufactured using 3D printing. The device used an improvement of the traditional Sobel detection algorithm, which extends the detection of edges in only the x and y directions to eight directions (0°, 45°, 90°, 135°, 180°, 225°, 270°, and 315°), completing the wound-edge detection by adaptive thresholding. The device can be controlled according to different shapes of sterilization area to adjust the positioning of a single plasma-jet tube in the horizontal plane for two-dimensional movement; the distance between the plasma-jet tube and the surface of the object to be sterilized can be also adjusted in the vertical direction. In this way, motors are used to move the plasma jet and achieve automatic, efficient, and accurate plasma sterilization. It was found that a good sterilization effect could be achieved at both the culture-medium level and the biological-tissue level. The ideal sterilization parameters at the culture-medium level were a speed of 2 mm/s and a flow rate of 0.6 slm, while at the biological-tissue level, these values were 1 mm/s and 0.6 slm, respectively. ARTICLE HIGHLIGHTS: • Image processing combining eight-direction Sobel edge detection and a median-filtering adaptive threshold was used for wound-edge recognition. • A device with x, y, and z degrees of freedom was designed and 3D printed. • An FPGA-based sterilization platform combining edge-recognition detection, a three-degree-of-freedom kinematic device, and a plasma injector was built to precisely sterilize wounds. [ABSTRACT FROM AUTHOR]

We present quasi-exact ab initio path integral Monte Carlo (PIMC) results for the partial static density responses and local field factors of hydrogen in the warm dense matter regime, from solid density conditions to the strongly compressed case. The full dynamic treatment of electrons and protons on the same footing allows us to rigorously quantify both electronic and ionic exchange–correlation effects in the system, and to compare the results with those of earlier incomplete models such as the archetypal uniform electron gas or electrons in a fixed ion snapshot potential that do not take into account the interplay between the two constituents. The full electronic density response is highly sensitive to electronic localization around the ions, and our results constitute unambiguous predictions for upcoming X-ray Thomson scattering experiments with hydrogen jets and fusion plasmas. All PIMC results are made freely available and can be used directly for a gamut of applications, including inertial confinement fusion calculations and the modeling of dense astrophysical objects. Moreover, they constitute invaluable benchmark data for approximate but computationally less demanding approaches such as density functional theory or PIMC within the fixed-node approximation. [ABSTRACT FROM AUTHOR]

In this study, a single-outer-spiral electrode with inductance of 20 μH is employed to couple the energy input of a bipolar nanosecond pulse for the purpose of generating a large-scale atmospheric pressure plasma jet. When the spiral electrode is wrapped around a plasma jet tube with a length of 35 cm, the electrical field can be optimized, resulting in a stable laminar flow field, and a plasma jet with a length and diameter larger than 14 cm and 1.2 cm can be generated. A comparative study of the bipolar and unipolar pulse excitation voltages is also conducted, showing that the maximum lengths of the plasma jet excited by a bipolar pulse voltage, positive pulse voltage, and negative are 14 cm, 10 cm, and 7 cm, respectively. The temporal and spatially resolved spectra of the plasma jets excited by both bipolar and unipolar pulses are investigated, respectively, and the main physiochemical processes of the active species and the plasma dynamics' evolution are discussed. [ABSTRACT FROM AUTHOR]

In this study, a disk-type bluff body was installed at the upper part of a nozzle exit, and the circular jet inside the nozzle was controlled using a dielectric barrier discharge (DBD) plasma actuator (DBD-PA). The effects of the changes in the excitation frequency of the jet induced by the DBD-PA on the jet diffusion were elucidated. The experiments included visualization of the jet cross-section, particle image velocimetry analysis, and velocity measurements using an I-type hot-wire anemometer. When the DBD-PA was driven at a specific burst frequency (900–1400 Hz), a lock-in phenomenon occurred, in which the frequency of vortices generated in the initial jet coincided with the burst frequency. This lock-in phenomenon suppressed the merging of vortices by generating vortices at regular intervals. When vortex merging was suppressed, the jet was less likely to be entrained into the recirculation flow generated by the bluff body, thereby increasing the downstream jet width and average flow rate. [ABSTRACT FROM AUTHOR]

Plasma-liquid interactions yield numerous physicochemical phenomena, rendering them promising for various applications. Plasma-based technology is proposed for water treatment due to its high efficiency in removing contaminants unattainable by conventional techniques. In this study, we employ an argon microwave plasma jet (MWPJ) to investigate methylene blue (MB) degradation. We observe a significant enhancement in the MB degradation rate in a covered system, attributed to increased air humidity promoting hydroxyl radicals (OH) production, which degrade approximately 95% of MB. Furthermore, the injection of O2 gas into the solution under the plasma generates more hydrogen peroxide (H2O2), around 30 mg/L compared to approximately 20 mg/L without injection, although the MB degradation efficiency is reduced. We evaluate MB degradation under various solution properties, revealing that increasing electrical conductivity decreases the MB degradation rate until it becomes independent for conductivities > 10,000 µS/cm. In these latter conditions, a non-conventional temporal evolution of solution conductivity was observed: a decrease during the first tens of minutes followed by a continuous increase for longer treatment time. Conversely, solution acidity minimally affects the MB degradation rate. The MWPJ is characterized by optical emission spectroscopy, showing stability over time and under various solution properties. The energy yield (Y50%) consistently demonstrates superior performance of the MWPJ in a closed environment compared to an open-to-air environment. Although its efficiency is relatively low compared to other systems, we anticipate improvements through parameter adjustments. [ABSTRACT FROM AUTHOR]

Atmospheric pressure plasmas (APPJs) are widely used for research purposes or industrial applications. There are plenty of different APPJs designed with various geometries and excitation frequencies ranging from kHz over RF (MHz) to fast ns pulses. A direct comparison of these APPJs is often challenging as the different geometries or the different excitation frequencies are not the same and can strongly influence plasma behaviour. In this work, this challenge is met and overcome by the use of an APPJ which can be operated at various excitation frequencies. kHz pulsing with a high voltage peak with µ s rise time, sinusoidal voltage pulse at 13.56 MHz and fast high voltage ns pulse were applied to the plasma jet used. The production of H 2 O 2 was investigated by treating liquids and measuring the H 2 O 2 concentration in the treated liquid. Fast ns pulses and RF excitation show similar results, while the kHz excitation is less effective in the H 2 O 2 production. [ABSTRACT FROM AUTHOR]

In this study, the transportation of reactive species from argon (Ar) and helium (He) atmospheric-pressure plasma jets (APPJs) to water is comparatively investigated using two-dimensional (2D) fluid models. For the same gas flow rate and reactive species concentration at the jet orifice, the transportation efficiency of the Ar APPJ is found to be higher than that of the He APPJ by 3.7 times. This is primarily attributed to the difference in the gas flow between the Ar and He APPJs. Ar has a higher molecular weight than air, which allows the reactive species in the Ar gas flow to sufficiently contact the water surface. He is much lighter than air, and consequently, the He gas flow floats upwards and inhibits transportation. Increasing the gas flow rate can reduce the floating of He and enhance the transportation of all reactive species in the He APPJ, but can only improve the transportation of short-lived species in the Ar APPJ. The use of shielding air gas reduces the floating of He and promotes the production of reactive species in the plasma plume, thus, the normalised concentration of the reactive species in the He APPJ-treated water increases drastically by 30.3 times. The numerical results conform to the trends observed in the available experimental data, which explains the reason why the Ar APPJ has stronger sterilization and anticancer effects than the He APPJ. The findings also serve as a reference for improving the He APPJ for biomedical applications. [ABSTRACT FROM AUTHOR]

Plasma-activated saline (PAS) holds immense potential for diverse applications, including antimicrobial activity, anti-inflammatory effects, and cancer therapy. This study introduces a novel approach utilizing a serially associated hybrid plasma discharge system, which combines dielectric barrier discharge (DBD) with a gliding arc plasma jet (GAPJ), to enhance the production of reactive oxygen and nitrogen species (RONS) in saline water. The serial configuration of DBD and GAPJ effectively amplifies the generation of RONS, as confirmed by optical emission spectroscopy, which revealed unique emissions associated with nitrogen and oxygen ions. Significant changes in the physicochemical properties of saline were observed, including reductions in pH and increases in oxidation–reduction potential and total dissolved solids, particularly during the initial activation phase. Real-time UV–Vis spectroscopy revealed the formation of key RONS such as hydrogen peroxide (H2O2), ozone (O3), nitrite (NO2‒), and nitrate (NO3‒), with distinct absorption bands emerging in the UV region. Raman spectroscopy further confirmed the impact of plasma treatment on the molecular structure of saline, showing a weakening of the hydrogen-bonding network. This work offers new insights into PAS production using the serial association of DBD and GAPJ, advancing its potential for various therapeutic applications. [ABSTRACT FROM AUTHOR]

Atmospheric repetitive He discharge with 10 ns current peak width and 3 × 10 11 V/s voltage front rise working in jet geometry is studied. This part deals with the ionization waves, electron density, and electric field dynamics. The electron density (n e) is measured by Stark broadening of the H Balmer β (H β) and He emission lines, the electric field is analyzed using Stark polarization spectroscopy, and the ionization waves are studied by fast imaging. We found that the ionization fronts propagate in the quartz tube with a velocity of about 5 × 10 5 m/s; this velocity slowly decreases along the tube but may jump in the open air at some conditions. In the space between electrodes, n e increases rapidly at the beginning, reaching about 7 × 10 15 cm − 3 , which corresponds to electron avalanche defining the discharge current peak. In the tube, the electrons are concentrated in the ionization wavefronts having low density (< 10 14 cm − 3 ). Before the avalanche, a macroscopic (electrode-induced) electric field dominates between the electrodes peaking at about 8 kV/cm as deduced from H β peak splitting, whereas during the avalanche, H β reveals a double-Lorentzian polarization-insensitive profile imposed by two electron populations. In the low-density electron group, n e does not exceed 10 14 cm − 3 , whereas the high-density group is responsible for the observed electron density peak formation. After a rapid decay of the electrode-induced field, the microscopic electric field (induced by space-charge) dominates, peaking at about 25 kV/cm after the electron density peak. Certain electric field anisotropy is also detected in the quartz tube, confirming the wavefront propagation. [ABSTRACT FROM AUTHOR]

This article presents an experimental investigation of an argon plasma jet. It examines a commercial argon plasma jet device's physical, chemical, and biological impacts, comparing findings against global standards. The study focuses on electrical features ensuring safety for patients and consumers, finding all leakage current values within established standards. Chemical analysis of emitted gases shows no detectable levels of harmful compounds near treated skin. Optical emission spectroscopy reveals bioactive compounds within the plasma jet. UV radiation emission remains within safety thresholds. Hyperspectral imaging shows temporary increases in skin characteristics posttreatment, reverting to baseline over time. Overall, the study demonstrates the safety and potential of the argon plasma jet in skin treatment. [ABSTRACT FROM AUTHOR]

Considerable interest has emerged in atmospheric pressure discharges within the microwave frequency range over the past decade, driven by the growing potential applications such as material processing, CO2 dissociation, waste treatment, hydrogen production, water treatment, and so forth. This review delves into the diverse types of atmospheric pressure plasma jets (APPJs) operated at microwave frequencies. The analysis integrates insights from an overall review that encapsulates the different types of geometry, characterizations, modeling, and various applications of microwave atmospheric plasma jets (MW‐APPJs). This paper will contribute to a comprehensive understanding of microwave plasma generated in the ambient atmosphere. The fundamental insights into these discharges are emerging, but there are still numerous unexplained phenomena in these inherently complex plasmas that need to be studied. The properties of these MW‐APPJs encompass a higher range of electron densities (ne), gas temperatures (Tg), electron temperatures (Te), and reactive oxygen and nitrogen species (RONS). This review provides an overview of the key underlying processes crucial for generating and stabilizing MW‐APPJs. Additionally, the unique physical and chemical properties of these discharges are summarized. In the initial section, we aim to introduce the primary scientific characterizations of different types of waveguide‐based and non‐waveguide‐based MW‐APPJs. The subsequent part focuses on the diverse modeling approaches for different MW‐APPJs and the outcomes derived from these models. The final section describes the potential applications of MW‐APPJs in various domains. [ABSTRACT FROM AUTHOR]

The SOLPS‐ITER3.0.8 code with new Grad‐Zhdanov module was applied for predictive modeling of tritium plasma and deuterium‐tritium mixture in tokamak JET. The moderate power scenario of shot JPN #85278 modeled earlier for deuterium plasma was taken as a starting point. Effect of puffing increase, which was applied in experiment, on divertor conditions and inter‐ELM tungsten sputtering for both working gases and on isotope separation in their mixture is analyzed. Both for attached and for semi‐detached outer targets, the tritium plasma shows moderate increase in SOL width compared to deuterium one. The tungsten sputtering at the outer target in the inter‐ELM period for tritium is an order of magnitude bigger than that for deuterium. The D–T separation in the D–T mixture is moderate. [ABSTRACT FROM AUTHOR]

The hydrogenic two‐point model (H‐2PM), an analytical model for the scrape‐off layer that predicts a common electron and ion temperature and density along a flux tube from a target temperature and density, is adapted to a single‐species helium (He) model, preserving the 2PM assumptions and analytical nature. Across a range of densities and heating powers, the predicted Te$$ {T}_e $$ is within 20eV$$ 20\kern0.3em \mathrm{eV} $$ of upstream measurements by high‐resolution Thomson scattering (HRTS) for low‐confinement He plasmas performed in JET ITER‐like wall (JET‐ILW). For high‐recycling conditions, He‐2PM predictions of ne$$ {n}_e $$ were within 10% of the Li‐beam diagnostic measurements, excluding the near‐SOL, when assuming Zeff=1$$ {Z}_{\mathrm{eff}}=1 $$, suggesting the divertor SOL was not fully ionised in the JET‐ILW He plasmas. [ABSTRACT FROM AUTHOR]

We calculate the medium modification factor for 5.02 TeV + Pb collisions. We use the Monte Carlo Glauber model to determine the parameters of the quark–gluon plasma fireball in jet events. Our calculations show that the jet quenching effect for turns out to be rather small. We have found that the theoretical as a function of the underlying event charged multiplicity density, within errors, agrees with data from ALICE [1] for 5.02 TeV + Pb collisions. However, the experimental errors are too large to draw a firm conclusion on the possible presence of jet quenching. [ABSTRACT FROM AUTHOR]

This research aim is to activate water using a plasma jet that works with argon gas and to study the effect of the plasma on the physicochemical properties of the water. The plasma consists of a power supply capable of supplying a high alternating voltage of up to 12 kV in the form of a sinusoidal wave with a frequency of 20 kHz. The temperature of the produced plasma (Te) was (1.028) eV, and its electron density (ne) was (4.392×1017) cm-3 at a flow rate of 1L/min. The physicochemical properties of the water are determined by determining the concentration of each of NO2, NO3, and H2O2, the pH of the water, and the water temperature during exposure to the plasma. The effect of storage time on the properties of the activated water is determined after 48 hours of exposure to plasma. The RONS species were measured using kits purchased from USA (Bartovation) Company manufactured for this purpose. The pH was measured with a pH meter, and the working gas temperature was remotely measured with an IR thermometer. The concentration of the three active species increases with exposure time, but the active species NO2 concentration decreases to zero at an exposure time of 120 minutes. The concentrations of the three components decrease with the decrease in the flow rate. The pH decreases with the exposure time until it reaches 2, and the temperature increases until it reaches 35oC. The concentration of NO3 increases with the increase of the water storage time. In the case of H2O2, the concentration increases slightly, then after 10 hours it begins to decrease exponentially, reaching a value close to zero after the passage of 48 hours. For NO2, its concentration begins to decrease exponentially from the start of storage and reaches a concentration close to zero after 48 hours of storage. The pH increases with the storage time, and the water reaches its natural state with a pH of 7 after 48 hours of storage. From this, it is concluded that the best storage time for PAW is ten minutes after the end of the activation process, and also that the activation time should be short, but not exceeding ten minutes. [ABSTRACT FROM AUTHOR]

Plasma treatment is necessary to optimize the performance of biomaterial surfaces. It enhances and regulates the performance of biomaterial surfaces, creating an effective interface with the human body. Plasma treatments have the ability to modify the chemical composition and physical structure of a surface while leaving its properties unaffected. They possess the ability to modify material surfaces, eliminate contaminants, conduct investigations on cancer therapy, and facilitate wound healing. The subject of study in question involves the integration of plasma science and technology with biology and medicine. Using a helium plasma jet source, applying up to 18 kV, with an average power of 10 W, polymer foils were treated for 60 s. Plasma treatment has the ability to alter the chemical composition and physical structure of a surface while maintaining its quality. This investigation involved the application of helium plasma at atmospheric pressure to polyamide 6 and polyethylene terephthalate sheets. The inquiry involves monitoring and assessing the plasma source and polymer materials, as well as analyzing the impacts of plasma therapy. Calculating the mean power of the discharge aids in assessing the economic efficacy of the plasma source. Electric discharge in helium at atmospheric pressure has beneficial effects in technology, where it increases the surface free energy of polymer materials. In biomedicine, it is used to investigate cytotoxicity and cell survival, particularly in direct blood exposure situations that can expedite coagulation. Comprehending the specific parameters that influence the plasma source in the desired manner for the intended application is of utmost importance. [ABSTRACT FROM AUTHOR]