Plasma Generation Research Articles

Effect of high voltage discharge on germination characteristics of vetch seeds at high altitude

High-voltage electrostatic fields and low-temperature plasma technology at atmospheric pressure have an important impact on biological growth promotion. Therefore, a multi-needle-column-plate corona plasma generator is proposed in this paper. The negative corona voltammetry characteristics of multi-needle-plate electrodes and multi-needle-column-plate electrodes with different electrode spacing are investigated experimentally, and the electric field distribution of the device is simulated. The device was also applied to vetch seeds at high altitudes to investigate the effect of discharge on germination and root length. The results show that the introduction of column electrodes can effectively improve the electric field distribution of the device so that the device can provide two modes of high voltage electrostatic field and corona plasma field, and ensure the uniform treatment of seeds when the electrode spacing is 3 cm. The treatment of this device accelerates seed germination and promotes root growth, and is more effective under the combined influence of higher electric field strength, ionic wind generated by the discharge, and the active species than a single factor with a lower electric field, as well as shortening the duration of action. The high voltage electrostatic fields at −3 kV, −6 kV, and −9 kV and the corona discharge plasma fields at −12 kV, −15 kV, and −18 kV can effectively accelerate the germination of vetch seeds as well as promote the root growth under the treatment time of 10 min, 20 min, and 30 min. The optimal conditions were −9 kV for 30 min and −15 kV for 10 min, respectively.

Optical and electric characteristics of CuO nanoparticle-doped ZnO thin films using thermionic vacuum arc deposition system

In this study, the thermionic vacuum arc (TVA) method was employed to fabricate thin films of zinc oxide (ZnO) doped with copper oxide nanoparticles (CuONPs). The primary objective was to investigate the influence of the substrate on the characteristics of the CuONPs-doped ZnO thin films. CuONPs were synthesized using both the solution plasma process and the high-voltage liquid plasma generation method, resulting in particle sizes ranging from 20 to 40 nm. The X-ray diffraction (XRD) pattern confirmed the polycrystalline nature of the CuONPs. The prepared CuONPs in powder form were blended with ZnO powder and utilized as an anode material for TVA discharge and coating. The structural, optical, elemental, and topological properties of the resulting thin films were systematically examined. The findings revealed that the deposited thin films exhibited a polycrystalline structure, with transparent and electrically conductive layers. Similar reflection values were observed for films deposited on both glass and indium tin oxide (ITO)-coated glass substrates. Nanostructures on the film surfaces were elucidated through field emission scanning electron microscopy images. The atomic ratios of Cu/Zn were determined as 1/3 and 1/10 for films deposited on uncoated and ITO-coated glass substrates, respectively. The mean grain size of the nanoparticles on the film surface measured approximately 17 nm for films deposited on uncoated glass substrates and 35 nm for those deposited on ITO-coated glass substrates. The film resistance was measured at 20 kΩ, indicating its suitability as a semiconductor. Analysis of the XRD pattern identified peaks corresponding to CuONPs and ZnO in the deposited films, affirming their polycrystalline nature. In conclusion, the deposited thin films exhibit favorable characteristics for semiconductor applications, and the coating method employed proves to be effective in producing high-quality thin films.

Simulation and experimental results of plasma opening switch operation with inductive and electron beam diode loads in different plasma regimes

This paper reports the experimental results of a plasma opening switch (POS) that operates at hydrogen and carbon plasma regimes confirmed based on the conduction bipolar limit of the plasma species and the availability of plasma species during the conduction based on the density profiles. The generator is the compact capacitor bank developed using the synchronization of four field distortion spark gap switches. The plasma source is coaxial cable plasma guns characterized using the Faraday cup plasma diagnostic. The experimental results are compared with the time domain simulation code in which the POS is represented as the dynamic resistance governed by the physical equations of the bipolar model. The experiments and simulations are compared for inductive load and dynamic load of accelerating gap of 5 mm between the anode and cathode at the load end. From the results, POS can be operated based on the availability of plasma species with proper synchronized triggering between the plasma gun firing and generator firing that can operate at low and high values of currents.

Microwave electrothermal thruster with surface wave plasma

AbstractA new microwave electrothermal thruster (MET) with small dimensions (length of 25 mm and diameter of 6 mm), utilizing surface wave (SW) plasma at low average power consumption Pav ˜ 2 W, is made. It uses microwaves at a frequency of 2.45 GHz for plasma generation within a dielectric chamber enclosed in a metal shield. The SW is excited at the plasma‐dielectric interface by a coaxial launcher and a standing wave is created due to the wave reflection from the shield. The high‐density plasma produced in this resonant chamber heats up the argon gas, which expands through the nozzle in the axial direction. The temperature of the gas decreases from 1900 K at atmospheric pressure to 1200 K at 10 Torr ambient pressure. This small‐sized MET shows stable low‐pressure operation with a thrust of 4 mN and an efficiency of 8% and is suitable for nanosatellite orbit control.

B meson production in Pb+Pb at 5.02 ATeV at LHC: Estimating the diffusion coefficient in the infinite mass limit

In the last decade a Quasi-Particle Model (QPM) has been developed to study charm quark dynamics in ultra-relativistic heavy-ion collisions supplying a satisfactory description of the main observables for D meson and providing an estimate of the space-diffusion coefficient Ds(T) from the phenomenology. In this paper, we extend the approach to bottom quarks describing their propagation in the quark-gluon plasma within an event-by-event full Boltzmann transport approach followed by a coalescence plus fragmentation hadronization. We find that QPM approach is able to correctly predict the first available data on RAA(pT) and v2(pT) of single-electron from B decays without any parameter modification w.r.t. the charm. We show also predictions for centralities where data are not yet available for both v2(pT) and v3(pT). Moreover, we discuss the significant breaking of the expected scaling of the thermalization time τth with MQ/T, discussing the evolution with mass of Ds(T) to better assess the comparison to lQCD calculations. We find that at T=Tc charm quark Ds(T) is about a factor of 2 larger than the asymptotic value for M→∞, while bottom Ds(T) is only a 20% higher. This implies a Ds(T) which is consistent within the current uncertainty to the most recent lattice QCD calculations with dynamical quarks for M→∞.

Effects of TiO2 Nanotubes and Reduced Graphene Oxide on Streptococcus mutans and Preosteoblastic Cells at an Early Stage.

The effects of TiO2 nanotube (TNT) and reduced graphene oxide (rGO) deposition onto titanium, which is widely used in dental implants, on Streptococcus mutans (S. mutans) and preosteoblastic cells were evaluated. TNTs were formed through anodic oxidation on pure titanium, and rGO was deposited using an atmospheric plasma generator. The specimens used were divided into a control group of titanium specimens and three experimental groups: Group N (specimens with TNT formation), Group G (rGO-deposited specimens), and Group NG (specimens under rGO deposition after TNT formation). Adhesion of S. mutans to the surface was assessed after 24 h of culture using a crystal violet assay, while adhesion and proliferation of MC3T3-E1 cells, a mouse preosteoblastic cell line, were evaluated after 24 and 72 h through a water-soluble tetrazolium salt assay. TNT formation and rGO deposition on titanium decreased S. mutans adhesion (p < 0.05) and increased MC3T3-E1 cell adhesion and proliferation (p < 0.0083). In Group NG, S. mutans adhesion was the lowest (p < 0.05), while MC3T3-E1 cell proliferation was the highest (p < 0.0083). In this study, TNT formation and rGO deposition on a pure titanium surface inhibited the adhesion of S. mutans at an early stage and increased the initial adhesion and proliferation of preosteoblastic cells.

Synthesis of Ni nanoclusters supported on diamond by plasma technique and their electrochemical properties

In this study, particles of synthetic undoped diamond (DN) obtained via the high pressure – high temperature method were coated with a nickel shell using metallic nickel plasma in a two-jet plasma generator with gas vortex and magnetic flux stabilization. Through the use of scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy, we observed the formation of a nickel diamond composite with a core-shell structure, where DN serves as the core and Ni nanoclusters form the shell (DN@Ni). The results of voltammetric analysis indicated that DN@Ni, when deposited on a graphite electrode, exhibited significant electrocatalytic activity in the oxidation of methanol and paracetamol in an alkaline electrolyte.

Generation of meter-scale hydrogen plasmas and efficient, pump-depletion-limited wakefield excitation using 10 GeV electron bunches

High repetition rates and efficient energy transfer to the accelerating beam are important for a future linear collider based on the beam-driven plasma wakefield acceleration scheme (PWFA-LC). This paper reports the first results from the Plasma Wakefield Acceleration Collaboration (E300) that are beginning to address both of these issues using the recently commissioned FACET-II facility at SLAC national accelerator laboratory. We have generated meter-scale hydrogen plasmas using time-structured 10 GeV electron bunches from FACET-II, which hold the promise of dramatically increasing the repetition rate of PWFA by rapidly replenishing the gas between each shot compared to the hitherto used lithium plasmas that operate at 1–10 Hz. Furthermore, we have excited wakes in such plasmas that are suitable for high gradient particle acceleration with high drive-bunch to wake energy transfer efficiency- a first step in achieving a high overall energy transfer efficiency. We have done this by using time-structured electron drive bunches that typically have one or more ultra-high current ( > 30 kA) femtosecond spike(s) superimposed on a longer (∼0.4 ps) lower current ( < 10 kA) bunch structure. The first spike effectively field-ionizes the gas and produces a meter-scale (30–160 cm) plasma, whereas the subsequent beam charge creates a wake. The length and amplitude of the wake depends on the longitudinal current profile of the bunch and plasma density. We find that the onset of pump depletion, when some of the drive beam electrons are nearly fully depleted of their energy, occurs for hydrogen pressure ⩾ 1.5 Torr. We also show that some electrons in the rear of the bunch can gain several GeV energies from the wake. These results are reproduced by particle-in-cell simulations using the QPAD code. At a pressure of ∼2 Torr, simulation results and experimental data show that the beam transfers about 60% of its energy to the wake.

Detection of FG-4592 and metabolites in equine plasma, urine and hair following oral administration.

FG-4592 is a hypoxia-inducible factor inhibitor that has been approved for therapeutic use in some countries. This class of compounds can increase the oxygen carrying capacity of the blood and thus have the potential to be used as performance enhancing agents in sports. The purpose of this study was to investigate the detection of FG-4592 and metabolites in equine plasma and mane hair following a multiple dose oral administration to two Thoroughbred racehorses, to identify the best analytical targets for doping control laboratories. Urine samples were also analysed, and the results compared to previously published urine data. Liquid chromatography-high resolution mass spectrometry was used for metabolite identification in urine and plasma. Liquid chromatography-tandem mass spectrometry was used for full sample analysis of urine, plasma and hair samples and generation of urine and plasma profiles. FG-4592 and a mono-hydroxylated metabolite were detected in plasma. FG-4592 was detected with the greatest abundance and gave the longest duration of detection, up to 312 h post-administration, and would be the recommended target in routine doping samples. FG-4592 was detected in all mane hair samples collected post-administration, up to 166 days following the final dose, showing extended detection can be achieved with this matrix. To the best of the authors' knowledge, this is the first report of FG-4592 and metabolites in equine plasma and hair samples. Urine results were consistent with the previously published data, with FG-4592 offering the best target for detection and longest detection periods.

Generation of Species-Specific High-Strength Plasma Activated Water at Neutral pH and its Antimicrobial Characteristics

Generation of Species-Specific High-Strength Plasma Activated Water at Neutral pH and its Antimicrobial Characteristics

Cold atmospheric plasma is bactericidal to wound-relevant pathogens and is compatible with burn wound healing

Burn wound healing can be significantly delayed by infection leading to increased morbidity and hypertrophic scarring. An optimal antimicrobial agent would have the ability to kill bacteria without negatively affecting the host skin cells that are required for healing. Currently available products provide antimicrobial coverage, but may also cause reductions in cell proliferation and migration. Cold atmospheric plasma is a partially ionized gas that can be produced under atmospheric pressure at room temperature. In this study a novel handheld Aceso Plasma Generator was used to produce and test Aceso Cold Plasma (ACP) in vitro and in vivo. ACP showed a potent ability to eliminate bacterial load in vitro for a number of different species. Deep partial-thickness and full-thickness wounds that were treated with ACP after burning, after excision, after autografting, and at days 5, 7, and 9 did not show any negative effects on their wound healing trajectories. On par with in vitro analysis, bioburden was decreased in treated wounds vs. control. In addition, metrics of hypertrophic scar such as dyschromia, elasticity, trans-epidermal water loss (TEWL), and epidermal and dermal thickness were the same between the two treatment groups.It is likely that ACP can be used to mitigate the risk of bacterial infection during the phase of acute burn injury while patients await surgery for definitive closure. It may also be useful in treating wounds with delayed re-epithelialization that are at risk for infection and hypertrophic scarring. A handheld cold plasma device will be useful in treating all manner of wounds and surgical sites in order to decrease bacterial burden in an efficient and highly effective manner without compromising wound healing.

Influence of cusp magnetic field configuration on plasma parameters of radio frequency driven negative ion source for CRAFT NNBI

Radio Frequency (RF) driven negative ion source is the preferred ion source for negative ion based Neutral Beam Injection system (NNBI). The plasma generator, which consists of RF driver(s) and an expansion chamber, is one of the key parts for NNBI. The distribution of cusp magnetic field which is generated by permanent magnets installed at the lateral wall of the expansion chamber is a common issue, due to the great influence on electron density, electron temperature and spatial uniformity of plasma density in the extraction area. Two kinds of configuration of cusp magnetic field (checkerboard type and symmetric type) and three types of arrangement of permanent magnets (with three, four and five rows of magnets) have been carried out with the approach of finite element and the experimental performance. On the RF negative ion source testbed, a moveable Langmuir probe has been adopted to investigate the characteristic of electron density and temperature near the extraction area. Since the symmetric type with three rows of permanent magnets generates the distribution of cusp magnetic field that contribute to extract the plasma from RF driver and improve the probability of particle collision easily, the higher electron density and the lower electron temperature was obtained via simulation. The experimental conclusion is that the symmetric type with three rows of permanent magnets leads to a higher electron density and lower electron temperature, showing a great agreement with simulation results. The results are helpful to optimize the structure and performance of high power ion source, and provide support for the development of large area RF negative ion sources with multi-driver.

Added insult to injury? The response of meat-associated pathogens to proposed antimicrobial interventions

Modern requirements for ‘green label’ meat products have led to the design of novel antimicrobial innovations which prioritise quality, safety and longevity. Plasma-functionalised water (PFW), ultraviolet light and natural antimicrobial compositions have been investigated and optimised for control of foodborne pathogens like Campylobacter jejuni and Salmonella enterica serovar Typhimurium. However, given the adaptive mechanisms present in bacteria under external stresses, it is imperative to understand the effect that sublethal treatment may have on the bacterial transcriptome. In this study, Salmonella Typhimurium and C. jejuni were treated with sublethal doses of ultraviolet light, a citrus juice/essential oil marinade, and ‘spark’ or ‘glow’ cold plasma generation system-produced PFW. Immediately after treatment, cells were lysed and RNA was extracted and purified. mRNA was converted to cDNA by reverse transcription-PCR and sequenced by an Illumina MiSeq® system. Sequences were filtered and analysed using the Tuxedo workflow. Sublethal treatment of Campylobacter jejuni and Salmonella Typhimurium led to increased immediate cellular and metabolic activity, as well as diversification in protein and metabolic functioning. There was further expression of pathogenesis and virulence-associated traits associated with spark PFW and marinade treatment of Salmonella Typhimurium. However, similar concerns were not raised with glow PFW or UV-treated samples. This study provides science-based evidence of the efficacy of multi-hurdle antimicrobial system using green-label marinades and PFW or UV to inactivate pathogens without upregulating virulence traits in surviving cells. This study will inform policymakers and food industry stakeholders and reinforces the need to incorporate in-line novel technologies to ensure consumer safety.Key points• Salmonella and C. jejuni showed increased cell activity in immediate response to stress.• Virulence genes showed increased expression when treated with natural antimicrobials and sPFW.• Reduced immediate transcriptomic response to gPFW and UV treatment indicates lower risk.

Terahertz generation in ripple density hot plasma under the influence of static magnetic field

Terahertz generation in ripple density hot plasma under the influence of static magnetic field

Wavefront distortion and compensation for weakly relativistic vortex beams propagating in plasma

The propagation of electromagnetic wave in plasma is one of the long-standing concerns in the field of laser plasma, and it is closely related to the researches of radiation source generation, particle acceleration, and inertial confinement fusion. Recently, the proposal of various schemes for generating intense vortex beams has led to an increasing number of researchers focusing on the interaction between intense vortex beams and plasmas, resulting in significant research progress in various areas, such as particle acceleration, high-order harmonic generation, quasi-static self-generated magnetic fields, and parametric instability. Compared with traditional Gaussian beams, vortex beams, featuring their hollow amplitudes and helical phases, can exhibit novel phenomena during propagating through plasma. In this work, we primarily focus on studying the influence of the propagation process on the wave structure of vortex beams before filamentation occurs. The three-dimensional particle-in-cell simulations show that weakly relativistic vortex beams exhibit wavefront distortion during their propagation in plasma. The distortion degree is closely related to the intensity of the electromagnetic wave and the propagation distance for a given plasma density. This phenomenon is theoretically explained by using a phase correction model that considers the relativistic mass correction of electrons. Additionally, we demonstrate that the wavefront distortion can be compensated for and suppressed by appropriately modulating the initial plasma density, as confirmed by three-dimensional particle simulations. The results of decomposing the wavefront into Laguerre-Gaussian (LG) mode components indicate that the wavefront distortion is primarily caused by high-order &lt;i&gt;p&lt;/i&gt; LG modes, and it is independent of other &lt;i&gt;l&lt;/i&gt; LG modes. Additionally, we extend the present investigation to the propagation of vortex beams in axially magnetized plasma, where the phase correction model can also effectively explain the occurrence of wavefront distortion. Our work can deepen the understanding of the interaction between plasma and strong vortex beams, and provide some valuable references for designing plasma devices serving as the manipulation of intense vortex beams in future research.

EMWP-RNN: A Physics-Encoded Recurrent Neural Network for Wave Propagation in Plasmas

EMWP-RNN: A Physics-Encoded Recurrent Neural Network for Wave Propagation in Plasmas

Transient Simulation of Electromagnetic Wave Propagation in Plasma Based on Dynamic Drude Model

Transient Simulation of Electromagnetic Wave Propagation in Plasma Based on Dynamic Drude Model

Methods and Applications for Amplified Bursts of Picosecond-Spaced Ultrashort Pulses

Generating packages of picosecond-spaced ultrashort pulses yields various advantages in their application in nonlinear spectroscopy, micromachining, and plasma generation. We outline methods of burst amplification, with a focus on recent advancements in the generation and application of amplified pulse bursts.

Synergistic low-temperature plasma (DBD) treatment of n-hexane gas

The experiment is based on a single dielectric barrier discharge (DBD) plasma generator, using micro-discharge to produce non-equilibrium plasma synergizing with two different catalysts (TiO2, 4A molecular sieve) to decompose n-hexane gas. In the n-hexane degradation experiment, the study investigates the influence of factors such as the type of catalyst, discharge voltage, and flow rate on the degradation rate of n-hexane. The experiments revealed that in all synergistic experiments with catalysts, the degradation rate of n-hexane increased with the decrease in flow rate and with the increase in voltage. Among the four catalysts selected, the 4A molecular sieve catalyst showed the best removal effect for n-hexane gas, reaching 73.2%.

High-pressure plasma etching up to 9 atm toward uniform processing inside narrow grooves of high-precision X-ray crystal optics

We developed a new etching technique using plasma generated at high pressure up to 9 atm. Operating at 9-atm pressure with a 30-μm-diameter wire electrode, we demonstrated the generation of well-ordered plasma at a narrow gap of ∼10 μm between the electrode and workpiece, and realized a high spatial resolution of <40 μm during processing. This technique should allow for the processing of high-precision X-ray crystal optical devices with compact and complex structures, such as a micro channel-cut crystal monochromator with an extremely narrow (sub-100 μm width) groove for realization of Fourier-transform-limited X-ray lasers with high intensity.