Structural and chemical evolution of fluorocarbon coatings on reactor walls and their run-to-run impacts on film deposition in C4F8/Ar/N2 plasma processing

Effect of cold plasma processing on the immunoreactivity, structure and functional properties of peanut protein

Abstract Kinetic Alfvén waves (KAWs) are ubiquitous in space and solar plasmas and are believed to be crucial for energy transfer and particle energization. Existing studies on KAWs primarily focus on the low-frequency approximation, where the wave frequency is much smaller than the proton cyclotron frequency (i.e., ω ≪ ω cp ). However, the wave properties of high-frequency KAWs with ω ≳ ω cp remain unclear. In this work, based on the two-fluid theory, we derive a general dispersion relation for KAWs spanning low-frequency to high-frequency regimes, and examine this dispersion relation and the electromagnetic properties of both low-frequency and high-frequency KAWs. Our findings reveal that, compared to low-frequency KAWs, high-frequency KAWs exhibit several distinct features: higher wave frequency ( ω ≳ ω cp ), propagation angle over a broader oblique angle range, significantly larger ratio of parallel to perpendicular electric field, and the magnetic helicity and magnetic compressibility that are highly sensitive to the plasma beta. The enhanced parallel electric field highlights the pivotal role of high-frequency KAWs in field-aligned particle acceleration. This work extends KAW theory to the high-frequency domain, providing key insights into KAW properties and the particle acceleration process in space and solar plasmas.

We report a scalable and sustainable method for synthesizing graphene oxide (GO) via a non-thermal atmospheric nano-second pulsed plasma (NSPP) process, using methane as the carbon source and water as the substrate. Unlike conventional chemical vapor deposition (CVD), which demands high temperatures, low pressures, and inert gases, this approach operates at ambient conditions without additional gas inputs. The plasma decomposes methane directly on or near the water surface, producing high-purity, single-layer GO with tunable oxygen content and flake size. Gas chromatography confirms substantial hydrogen generation and minimal greenhouse gas emissions. Atomic Force Microscopy (AFM) analysis verifies single-layer morphology. Scaling the process with a four-gap reactor yields 5 g of GO per day, exceeding conventional CVD output while reducing cost and environmental impact. This plasma-driven strategy provides an energy-efficient route for large-scale GO production, with potential applications in electronics, energy storage, coatings, and concrete composites.

Nuclear waste management represents a challenge due to the hazardous characteristics. The most efficient alternative is to prevent improper disposal, thereby avoiding environmental harm and optimizing the resources needed for transport and storage, which in turn minimizes the associated costs. Therefore, the objective of this study is to evaluate the use of plasma technology in waste management for radioactive waste. To understand the impact of implementing a plasma reactor in the radioactive waste management systems, various scenarios were created to analyse the behaviour, particularly in terms of disposal costs for this waste, in this studied case. In light of the present work, the methodology, positive results and analyses may encourage further studies for the development of plasma systems with greater capacity and plasma processes designed to treat low-level radioactive waste. It is essential to acknowledge a limitation in this study, which is the existence of various factors and experimental conditions that can influence the performance of the plasma thermal process. There is also a need for test procedures specifically designed to evaluate the immobilization of radioactive waste.

Distinct material phase modulation is widely regarded as a key strategy for tailoring the surface properties of nano-frameworks. Plasma has emerged as an effective method for in situ phase modulation directly on substrate surfaces. However, the persistent vertical bombardment of reactive species in a conventional plasma system inevitably leads to excessive surface etching, thereby compromising the distinction and quality of surface structural engineering. Herein, we introduce a novel magnetically confined plasma strategy that enables the unique phase modulation of iron nitride nano-frameworks on iron substrates. By varying the magnetic field strength, the resultant iron nitride phase transitions from orthorhombic Fe2N to trigonal Fe2N, with a well-defined exposed facet, is achieved. In contrast, the conventional plasma nitridation predominantly yields hexagonal FeN. Operando plasma diagnostics and numerical simulations are employed to elucidate the underlying mechanism governing phase modulation. The superior distinction of phase modulation via magnetically confined plasma processing is further validated by comparing with conventional plasma nitridation under varying discharge parameters. Such apparent structural differences of nitrides via magnetically-confined plasma are confirmed through the corresponding electrocatalytic performance evaluation and theoretical calculations. Such an approach offers a promising pathway for the distinct structural engineering of nitrides directly on the substrate surface toward improved electrocatalytic behavior.

Direct growth of graphene among nanocarbons on catalyst- and seed-free insulators, which offers a technical advance in methodologically straightforward simplicity and avoiding the post-growth transfer process, has been extensively investigated toward evolving a wide range of applications. In this study, plasma-enhanced chemical vapor deposition (PECVD) instead of thermal CVD (TCVD) is adopted for lowering the on-insulator growth temperature and gaining new insight into the fundamental growth-process of 2D graphene in connection with 1D single-walled carbon nanotubes (SWNTs). It is found for the first time that PECVD of low-influx plasmas and—energy ions facing an insulating growth-substrate of naked quartz glass enables SWNTs, single-layer graphene (sGPN), and a few-layers graphene (fGPN) to grow at critical ambient temperature of 700 ℃, where an equilibrium state is sophisticatedly maintained between carbon-source deposition and etching of unwanted materials. This temperature is substantially lower than 1100–1600 ℃ in the cases of TCVD so far. Furthermore, when the plasma influx and ion energy is gradually increased at the same temperature, only the 2D nanocarbon composed of sGPN and turbostratic graphite in the form of a mixture isobserved to grow while SWNTs and fGPN disappear.

Dielectronic recombination (DR) is widely recognized as a fundamental atomic process in many astrophysical and laboratory plasmas, where it plays a crucial role in determining ionization balance and level populations over a broad temperature range. Reliable DR resonance strengths and plasma rate coefficients for such plasma modeling can be computed using the Jena Atomic Calculator (JAC)—a relativistic code based on the multiconfiguration Dirac–Hartree–Fock (MCDHF) method. In this work, we investigate the DR of Li-like Ar15+ ions in their ground state (2s), focusing on resonances associated with the fine-structure core excitations 2s1/2→2p1/2,3/2. The resulting fine-structure-resolved DR resonance strengths and plasma rate coefficients are in good agreement with recent high-resolution DR measurements of Ar15+ ions performed at the Main Cooler Storage Ring (CSRm) in Lanzhou, China. These results provide a stringent benchmark for JAC calculations and support their applicability in plasma modeling.

We develop a semi-analytic theory for describing nonadiabatic bound-bound, free-bound, bound-free, and free-free photoprocesses in heteronuclear ions in the regime of the superlinear potential energy curve crossing. It extends the previous semiclassical method for calculating the absorption and emission spectra of strongly and moderately bound diatomic species based on the linear curve crossing model and can be used for molecules and ions with small dissociation energies, D0 ≲ kBT. The use of quasicontinuum approximation for rovibrational levels allows us to give a unified description of the integral contributions of the discrete and continuous spectra of the molecular species with linear and superlinear crossings to the effective cross sections and rate coefficients of the radiative processes in the systems studied. Specific calculations were performed for the excimer-like NeXe+ ion (DeNeXe+=37.3 meV). Potential energy curves and dipole transition matrix elements are evaluated using abinitio multi-reference calculations with a perturbative description of relativistic effects. In contrast to ArXe+ and KrXe+ ions studied previously, the main contributions to the absorption spectra of NeXe+ are due to bound-bound transitions and photoassociation. The emission spectra at room temperatures are determined predominantly by the bound-bound transitions, while at temperatures above 450K, the most significant contribution to the radiation is made by bound-free phototransitions. Our calculations are in good agreement with the available experimental data. The results obtained are of interest for chemical physics, spectroscopy of weakly bound molecular systems, and physics of radiative processes in gases and plasmas, as well as for the kinetics of active media of excilamps and gas lasers based on noble gas mixtures.

In this study, the growth of vertical graphene (VG) nanosheets on copper (Cu) substrates in a direct-current plasma-enhanced chemical vapor deposition (PECVD) system was studied. The plasma process during the VG growth was characterized using a high-speed camera and optical emission spectroscopy. Results showed that the plasma composition remained constant, but the overall plasma intensity increased with increasing substrate open area (OA). At low OAs of > 0.05, VG growth was limited to edges, and the VG height increased gradually to reach 700 nm as more reactants became readily available. Two distinctive regimes were identified: diffusion-limited growth at OAs < 0.6, and kinetic-limited growth at OAs > 0.6 for Cu meshes and screens. Under the diffusion-limited regime, VG growth occurred preferentially from the substrate edge toward the center. Therefore, the deposition time was extended to achieve uniform VG deposition. However, in the kinetic-limited regime, the increased availability of reactants did not alter the VG height, which remained at 700 nm. The kinetic-limited deposition was uniform across the substrate due to less plasma screening. This study sheds light on the growth mechanism of VG on perforated substrates, opening new avenues to control deposition on Cu substrates within plasma-screened interfaces.

The growth and study of living cells outside their native organisms forms the foundation of modern biology and underpin medicine. It has led to the identification of stem cells and the development of methods that can reprogram mature cells into pluripotent states, creating enormous potential for new therapies that can cure previously untreatable conditions and enable the repair of patient-specific tissues and organs. Accessing these advances, however, will require the development of sophisticated new cell culture materials and technologies. This Perspective article reviews the development of cell culture and current cell culture capabilities, with particular attention to the influence of spatial and temporal factors. We discuss traditional 2D culture, the complexities of 3D systems, and the emergence of 2.5D approaches as an alternative to high throughput 2D systems. Untapped potential and barriers to progress are identified while the new materials and technologies needed to drive the field forward are discussed.

Coupled effects of plasma and thermal processes on interfacial performance of flax-fiber/thermoplastic composites

Valorising crude glycerol, a major by-product of biodiesel production, is essential for advancing a circular chemical economy. Traditional methods of oxidising crude glycerol to produce value-added chemicals such as glycolic acid (GcA) and dihydroxyacetone (DHA) typically require noble metal catalysts and energy-intensive conditions. Herein, we present a catalyst-free, non-thermal plasma (NTP) process that operates in the liquid phase at ambient temperature and pressure. This novel approach enables the selective oxidation of glycerol into GcA and DHA without the need for added reagents or catalysts. With a deposited power of 9.6 W and short residence time, 100% selectivity towards GcA was achieved with 7% glycerol conversion. Extending the treatment time to 60 min increased glycerol conversion to 35%, with selectivities of 58% for GcA and 36% for DHA. These results highlight the potential of liquid-phase NTP as a sustainable and efficient method for upgrading crude glycerol under mild conditions.

Context . As an unmagnetized planet, Venus lacks an intrinsic magnetic field, leading to the direct interaction with the solar wind, which results in differences in physical processes within its magnetosphere–ionosphere (MI) system compared to Earth. With intense solar wind disturbances, it has been suggested that interplanetary coronal mass ejections (ICMEs) have a pronounced effect on Venus. Aims . This study aims to investigate the responses of the Venusian plasma environment to ICMEs. A simulation driven by a real ICME event that occurred on 5 November 2011, was conducted to systematically and quantitatively analyze the plasma processes in Venusian magnetosphere. During this event, the solar wind dynamic pressure at the model input increased by a factor of up to 4.8, while the interplanetary magnetic field (IMF) strength was enhanced by a factor of 1.9. Methods . The numerical simulation for Venusian plasma environment uses a multi-fluid global magnetohydrodynamics (MHD) model, coupled with the uniform neutral atmosphere. Utilizing the upstream magnetic field data from VEX and idealized solar wind plasma parameters as model inputs, we examine the response of Venusian plasma environment after the ICME arrival. Results . Venusian plasma environment and boundaries respond rapidly on the order of minutes. During the ICME, the subsolar bow shock location exhibits an inverse-linear proportionality to the fast magnetosonic Mach number. Meanwhile, the variation in boundaries’ locations demonstrates that high solar wind dynamic pressure and an enhanced IMF display compressive and expanding effects, respectively. The total integral of the ions’ escape rate shows that under ICME passage, the O + escape rate of Venus exhibits a sustained increase, from 6.0 × 10 24 s −1 to 3.0 × 10 25 s −1 . Both solar wind dynamic pressure and IMF strength enhance ion escape, with dynamic pressure dominating this process. Conclusions . The simulation driven by a real ICME event demonstrates severe, rapid, and complex responses of Venusian plasma environments, accompanied by an order-of-magnitude enhancement O + escape rate. These results could advance the understanding of the long-term evolution of terrestrial planets and provides references for the scientific targets of future missions.

Highly efficient single-step microwave plasma conversion of hazardous aromatic hydrocarbons into few-layer graphene.

Abstract Electron cyclotron harmonic (ECH) waves, a subset of electron Bernstein modes, are characterized by their distinct harmonic frequency structures. In the outer magnetosphere of the Earth, these waves play a vital role in electron scattering, pitch‐angle diffusion, and the subsequent precipitation of particles into the ionosphere. In contrast, their properties in the vicinity of the Lunar surface remain relatively poorly understood. In this study, we investigate the statistical characteristics of ECH waves using 8 years of observations from the ARTEMIS mission, with the objective of systematically characterizing their behavior across diverse Lunar plasma environments. Our analysis indicates that the overall occurrence rate of ECH waves within the region is approximately 0.099%, but this rate rises to more than 1% on the anti‐sun side in close proximity to the Moon. Moreover, the majority of ECH wave events are detected when the Moon resides within the Earth's magnetotail. On the anti‐sun side, enhanced ECH wave amplitudes are most pronounced in the near Lunar surface region. These results demonstrate that the local Lunar plasma environment strongly influences ECH wave activity, with Lunar magnetic field anomalies significantly modulating the occurrence rate of ECH waves while exerting no substantial influence on their amplitude. Collectively, these findings provide new insights into the plasma processes operating near the Lunar surface.

Integrated physiological and multi-omics insights into Chlorella mutagenized by atmospheric and room temperature plasma for enhanced saline aquaculture wastewater treatment and bioresource production.

Insights into plasma-catalytic degradation of diethyl phthalate over solvent-regulated BiOBr: Experiments and density functional theory.

Gallium nitride (GaN)-basedhigh-electron-mobility transistors(HEMTs) are key to high-power and high-frequency electronics owingto their wide bandgap, high breakdown field, and ability to form ahigh-density two-dimensional electron gas (2DEG) at the AlGaN/GaNinterface. For power-switching systems, enhancement-mode (E-mode)operation, where devices remain normally off at zero gate bias, ispreferred for intrinsic failsafe behavior and reduced standby power.However, conventional E-mode strategies, such as deep gate recessingor p-type gate insertion, often introduce fabrication complexity,surface damage, and long-term instability. Here, we demonstrate agate-localized CHF3 plasma process that simultaneouslyproduces a self-limiting recess with a fluorine-terminated surface,enabling a normally off AlGaN/GaN HEMT. Fluorine incorporation compensatespolarization-induced charges and drives a positive shift in thresholdvoltage (Vth), whereas hydrogen speciesgenerated during plasma exposure passivate etch-induced Ga-relateddefects and suppress interface-trap formation. By confining plasmaexposure to the gate region, this method mitigates surface degradationand charge trapping typically observed with CF4 processing,achieving precise and stable Vth controlwithout deep gate recessing. The fabricated devices exhibit normallyoff operation while maintaining low gate leakage under bias stress.This single step, lithographically confined approach offers a practicalroute toward E-mode GaN HEMTs for energy-efficient, high-frequency,and high-power electronic systems.

Inductively coupled plasmas (ICPs) are commonly utilized for etching processes in the microelectronic industry. Of which, dual-coil antenna is introduced as a potential technique to improve the plasma uniformity of ICPs in the literature. In this work, we investigate electronegative chlorine (Cl2) ICPs used in realistic processing and their improvement of radial uniformity via adjusting the current amplitudes and phase shift between the inner and outer coils of the dual-coil antenna. It is found that as the inner-to-outer coil current amplitude ratio decreases, the peak of electron and ion density gradually moves away from the radial center. When the wall recombination coefficient of Cl is 0.007, optimized uniformity for electrons and Cl+ is achieved at an inner-to-outer current ratio of 1:2, whereas Cl2+ attains best uniformity at a ratio of 1:1. Furthermore, the lower inner-to-outer coil current ratio is found to result in the better uniformity for the neutral Cl atom and excited state chlorine molecule species. In addition, adjusting the phase shift also significantly changes the plasma density profile. Simulation results show that the phase shift of π yields the highest uniformity for plasma neutrals, while charged particles show a species-dependent behavior. Furthermore, a comparison of different wall recombination coefficients of the Cl atom reveals its significant impact on species uniformity. Validations of the simulations are done against experiments through confirming the increasing trend of electron density vs coil power. This work demonstrates that the inner-to-outer current amplitude ratio and phase shift of the dual-coil antenna in electronegative Cl2 ICPs offers an effective control of the plasma uniformity for different plasma species, providing valuable insights into plasma processing applications that requires high uniformity.