Plasma Generation Research Articles

Efficiency scaling of inductively coupled plasmas for radio frequency propulsion systems

AbstractA generalized inductively coupled plasma (ICP) efficiency model is derived, which may be used to predict plasma generation efficiency with many types of radio frequency (RF) electric propulsion system. The analytical ICP discharge model is used to examine device scaling, and investigate trends in ICP performance as a function of geometry and system inputs. The ICP efficiency model is applied to an analytical RF cathode model to predict device behavior. Results from the updated RF cathode model show improvements in agreement with experimental data.

Laboratory Simulations of Plasma Generated Around the Atmospheric Reentry Spacecraft

In this paper, plasma will be generated in a laboratory as a simulation of what happens to spacecraft when they enter the atmosphere of Earth. Parameters of plasma generation were determined in terms of pressures of 0.1, 0.2, 0.3, 0.4, and 0.5 mbar and generation energy 200 W. The parameters of the generated plasma were calculated using the optical emission spectroscopy two intensity ratio method, and the electron temperature, electron density, Debye length, and plasma frequency were calculated. Compare the results with the actual results, electron temperatures were 2.26–1.71 eV and plasma frequency 8.09 x1011-6.7x1011 at 0.1-0.5 mbar pressure.

Apoptotic Impact of Heliox Cold Plasma on a Cervical Cell Line Using Gold Nanoparticle-Doped Graphene Oxide Nanosheets

Background: Invasive cervical cancer is recognized as the second most common malignancy in women after breast cancer. Objectives: This study investigates, for the first time, the effect of gold nanoparticle-doped graphene oxide (GO) nanosheets on the human epithelial carcinoma (HeLa) cell line in the presence of heliox cold plasma. Methods: Graphene oxide nanosheets were synthesized using the Hummer method and then doped with gold nanoparticles. The nanoparticles were characterized by transmission electron microscopy (TEM), and the diffraction peaks of GO and gold nanoparticles were confirmed through X-ray diffraction (XRD) analysis. Additionally, the optical absorbance of the nanoparticles was measured in the range of 200 - 900 nm using UV-Visible spectroscopy. A plasma generator was fabricated to produce cold plasma using helium (He) and oxygen (O₂) gases at a 99:1 ratio. The radicals generated by the cold plasma were analyzed via optical emission spectroscopy (OES). Cell treatment was conducted by applying various concentrations of GO and GO/Au nanoparticles. Cellular phenotype was monitored through optical microscopy, and biocompatible concentrations of both nanoparticles were determined using the 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay. Subsequently, cold plasma at varying distances and durations was applied to the nanoparticle-treated cells. The generated radicals and the expression of apoptotic genes in treated cells were assessed using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and real-time PCR, respectively. Results: The width of the bacillus-like gold nanoparticles was 15.13 ± 0.96 nm. The cold plasma generated radicals such as N2I2⁺, N2II1⁻, He•, and O⁻•. XRD analysis confirmed the successful coupling of gold onto the GO nanosheets. The biocompatible concentrations of GO and GO/Au nanoparticles were found to be 30 µg/100 µL and 20 µg/100 µL, respectively, as determined by the MTT assay. Radical formation increased as incubation time was extended from 30 to 60 seconds. Furthermore, real-time PCR analysis demonstrated the highest levels of p53, Bax, and caspase 3/8 expression at a plasma exposure time of 60 seconds in the composite-treated group, while Bcl2 expression was significantly reduced. Conclusions: The findings suggest that the parameters of heliox cold plasma and the concentrations of GO/Au nanoparticles must be optimized to effectively induce apoptosis in cervical cancer cells.

High-order harmonic generation in boron carbide laser-induced plasma: comparison with carbon and boron plasmas, two-color-pumping-induced enhancement, quasi-phase-matching, and tuning of harmonics

High-order harmonic generation in boron carbide laser-induced plasma: comparison with carbon and boron plasmas, two-color-pumping-induced enhancement, quasi-phase-matching, and tuning of harmonics

Highly Efficient and Integrated Nonlinear Airy Beams Generation

AbstractOwing to its peculiar non‐diffraction, self‐acceleration, and self‐healing properties, the Airy beam has attracted a great deal of attention in various fields such as micro‐manipulation, plasma generation, and optical microscopy. To date, it is still a challenge to generate nonlinear Airy beams with microstructure efficiently, thus limiting applications of such Airy beams. Here, a novel and efficient method for generating Airy beams is experimentally demonstrated by microstructure on a nonlinear crystal surface, which is fabricated by a focused ion beam (FIB) technique. The second‐harmonic (SH) Airy beams are generated in the far field and characterize their intensity distributions, which agree well with theoretical results. Then, the self‐accelerating and self‐healing properties of the generated SH Airy beams are demonstrated. Besides, the normalized efficiency of SH Airy beams is measured at (1.44 × 10−5%W−1), and compare the efficiency of different methods of generating nonlinear Airy beams, which shows the advantages of this method. The proposed method of generating nonlinear Airy beams shows great potential for integrated optics, optical micro‐machining, and advanced imaging.

A mechanistic model of in vitro plasma activation to evaluate therapeutic kallikrein-kinin system inhibitors.

The kallikrein-kinin system (KKS) is a complex biochemical pathway that plays a crucial role in regulating several physiological processes, including inflammation, coagulation, and blood pressure. Dysregulation of the KKS has been associated with several pathological conditions such as hereditary angioedema (HAE), hypertension, and stroke. Developing an accurate quantitative model of the KKS may provide a better understanding of its role in health and disease and facilitate the rapid and targeted development of effective therapies for KKS-related disorders. Here, we present a novel, detailed mechanistic model of the plasma KKS, elucidating the processes of Factor XII (FXII) activation, the kallikrein feedback loop, cleavage of high molecular weight kininogen leading to bradykinin (BK) production, and the impact of inhibitors. The model incorporates both surface and solution-phase reactions of all proteins in the KKS, describing how binding site concentration affects the rate of surface reactions. The model was calibrated and validated using a variety of published and in-house experimental datasets, which encompass a range of dextran sulphate (DXS) concentrations to initiate contact activation and various KKS inhibitors to block bradykinin production. Our mathematical model showed that a trace amount of activated FXII is required for subsequent FXII activation. The model also reveals a bell-shaped curve relationship between the activation of the KKS and the number of DXS surface binding sites. Simulations of BK generation in healthy and HAE plasma demonstrated the impact of C1 esterase inhibitor (C1inh) deficiency via increased peak BK levels and accelerated formation in HAE plasma. The efficacy of KKS inhibitors, such as CSL312, ecallantide, and C1inh, was also evaluated, with CSL312 showing the most potent inhibition of BK generation. The present model represents a valuable framework for studying the intricate interactions within the plasma KKS and provides a better understanding of the mechanism of action of various KKS-targeted therapies.

A new optimization strategy, the influence of hollow electrode chamfers on the development of helium atmospheric pressure plasma jets

This work suggests applying chamfering treatment to the plasma generator of the empty electrode structure. Enhancing the electrodes’ physical structure can significantly improve plasma characteristics without requiring intricate control systems. Experiments have shown that changes in the electrode’s shape can lead to changes in the formation of the atmospheric pressure plasma jet. Specifically, our observations indicate that an increase in the chamfer radius leads to an increase in the ignition voltage and a greater density of reactive species inside the jet. We developed a multi-channel equivalent circuit model to describe the discharge process of a plasma jet. Then, using the mixed layer theory, we investigated the effect of the chamfer radius on the plasma jet. Our findings suggest that chamfering increases the effective discharge area, resulting in more discharge channels in the model. This leads to a higher density of reactive species. Additionally, chamfering improves the mixing of helium and air, increasing the concentration of N2 and O2. This consumes some of the avalanche electrons and raises the ignition voltages, ultimately enhancing the chemical reactivity of the plasma jet. This work provides new ideas for the optimization strategy of atmospheric pressure plasma radiation devices.

A Study of the Features of Coating Deposition on a Carbide Substrate Using Preliminary Etching with Glow-Discharge Plasma

The properties of coatings obtained using two surface preparation methods were compared: heating and etching by ion bombardment with plasma generation by arc evaporators and heating and etching by a glow discharge. A Ti-TiN-(Ti,Cr,Al)N coating was deposited. The use of a glow discharge provides better resistance of the coating to destruction during the scratch test and wear resistance of metal-cutting tools when turning steel. As the cutting speed increases, the advantage in wear resistance of the coating deposited using a glow discharge increases. During the process of heating and etching by ion bombardment with metal ions, a nanolayer rich in cobalt and tooling elements (iron, molybdenum) is formed in the area of the interface of the coating and the carbide substrate. When heated and etched by a glow discharge, such a layer does not form. When using both methods, there is identical diffusion of tungsten into the coating and diffusion of chromium and possibly titanium into the substrate. Thus, the glow-discharge heating and etching method can be effectively used in the process of PVD coating deposition.

Dynamic characterization of plasma and combustion wave interactions during millisecond-nanosecond combined laser-induced enhanced damage on fused silica

Fused silica, which is widely used in optical systems, limits the load capacity of the optical system when it is damaged by laser irradiation. In this paper, a combined millisecond-nanosecond pulsed laser induced triple combustion wave dynamics model for fused silica generation is developed. The relationship between pulse delay and the dynamic propagation of plasma and combustion waves induced by combined laser-induced fused silica was studied from three aspects: theory, simulation, and experiment. The results show that the energy deposition of the nanosecond laser injects energy into the dilute plasma, which increases the speed of the double-burning wave to form a triple-burning wave. In addition, it was found that the combined effect of viscous shear between the plasma plume and the air exacerbates the degree of imbalance in the Knudsen layer instantaneously releasing pressure and increasing the complexity of plasma and combustion wave propagation, recoil pressure produces a more complex crack network on the fused silica surface. The results provide a better understanding of the propagation properties of plasma and triple-burning waves during combined millisecond-nanosecond induced fused silica damage.

Interactions of localized wave and dynamics analysis in the new generalized stochastic fractional potential-KdV equation.

In this paper, we investigate the new generalized stochastic fractional potential-Korteweg-de Vries equation, which describes nonlinear optical solitons and photon propagation in circuits and multicomponent plasmas. Inspired by Kolmogorov-Arnold network and our earlier work, we enhance the improved bilinear neural network method by using a large number of activation functions instead of neurons. This method incorporates the concept of simulating more complicated activation functions with fewer parameters, with more diverse activation functions to generate more complex and rare analytical solutions. On this basis, constraints are introduced into the method, reducing a significant amount of computational workload. We also construct neural network architectures, such as "2-3-1," "2-2-3-1," "2-3-3-1," and "2-3-2-1" using this method. Maple software is employed to obtain many exact analytical solutions by selecting appropriate parameters, such as the superposition of double-period lump solutions, lump-rogue wave solutions, and three interaction solutions. The results show that these solutions exhibit more complex waveforms than those obtained by conventional methods, which is of great significance for the electrical systems and multicomponent fluids to which the equation is applied. This novel method shows significant advantages when applied to fractional-order equations and is expected to be increasingly widely used in the study of nonlinear partial differential equations.

On Velocity Stopbands in Electrostatic Solitary Wave Propagation in Magnetospheric Plasma in the Presence of an Ion Beam—Application in the Solar Wind

Satellite observations in the Earth’s magnetosphere suggest a coexistence of different types of ion populations, such as protons and heavier helium ions (alpha particles) transported by the solar wind. We have undertaken an investigation, from first principles, of the conditions for the occurrence of electrostatic solitary waves in such a multi-ion plasma environment. Nonlinear analysis has been employed to explore the effect of an ion beam on the occurrence of stopbands in a multicomponent plasma consisting of Boltzmann electrons and two ion species, modeled as cold and warm (adiabatic) ions. A “stopband” is an interval of pulse speed (mach (Mach number) values in which solitary waves cannot propagate. Such stopbands are known to exist in relation to fast ion-acoustic solitary waves (exclusively). Our parametric analysis reveals that the stopband widens over the range of cold ion charge density (values) upon increasing speed of a hot ion beam moving along the direction of wave propagation. However, the stopband becomes narrower in the case of a counterpropagating beam. Similarly, the streaming of a cold ion beam fluid along (or antiparallel) to the wave direction leads to the narrowing (or widening, respectively) of the stopband. The fast soliton existence (velocity) domain is characterized by two critical points (a crossover and a turning point), which are affected by the beam. Our study could be relevant to understanding energy dissipation processes in the fast solar wind associated with relative drifts between the major (protons) and minor (alpha particles) ions which results in the heating of both species.

Surface cleaning with atmospheric pressure plasma jet investigated by in-situ optical emission spectroscopy and laser-induced breakdown spectroscopy

Cleaning of surfaces with atmospheric pressure plasma jet (APPJ) is investigated by in-situ optical emission spectroscopy (OES) and laser-induced breakdown spectroscopy (LIBS). The APPJ device operates a spark discharge of kW power in Argon gas flow resulting in a powerful plasma jet expanding into air. For cleaning experiments samples are coated with lubricant layers of 1.1 to 7.1 µm thickness. Light collected at the sample surface during APPJ treatment is analyzed spectroscopically and used to monitor the cleaning process. LIBS chemical imaging delivers spatial cleaning profiles of plasma treated surfaces. From measured emission intensities of CN molecular band and Na atomic line the cleaning efficiencies for carbon and Na containing contaminants are determined. The power of APPJ plasma generator, distance between sample and jet nozzle, scan speed, and Argon gas flow are varied to optimize the surface treatment. Thermal and non-thermal processes contribute to cleaning. For the carbon containing contaminant thermal processes are dominating (∼90 %) while also non-thermal processes (∼30–45 %) are relevant for the Na containing component. A cleaned surface area per time from 0.3 to 10 cm2/s is investigated. Cleaning efficiency up to 95 % is obtained highlighting the potential of APPJ surface cleaning under ambient conditions.

Coupling of Fluid and Particle-in-Cell Simulations of Ambipolar Plasma Thrusters

Ambipolar plasma thrusters are an appealing technology due to multiple system-related advantages, including propellant flexibility and the absence of electrodes or neutralizer. Understanding the plasma generation and acceleration mechanisms is key to improving the performance and capabilities of these thrusters. However, the source and plume regions inside are often simulated separately, and no self-consistent strategy exists which can couple these different simulations together. This paper introduces the MUlti-regime Plasma Equilibrium Transport Solver (MUPETS), a self-consistent coupled model integrating a fluid solver for the plasma dynamics in the source, which are collision-driven, with a kinetic Particle-In-Cell (PIC) code for the plasma dynamics in the magnetic nozzle, which involve expansion across a diverging magnetic field. The methodology begins by solving the plasma source with the classical Bohm condition at the thruster’s throat. The resulting plasma profiles (density, temperature, speed) are input into the PIC code for the magnetic nozzle. The PIC code calculates the plasma plume expansion and determines the electric field at the thruster’s throat. This electric field is then used as a boundary condition in the fluid code, where it replaces the Bohm assumption, and the fluid simulation is repeated. This iterative process continues until convergence. In comparing the MUPETS results with those for an experimental thruster, the plasma densities at the thruster’s throat differed by less than 2–5% between the fluid and PIC regions. The thrust predictions agreed with the experimental trend, and were kept well within the measurement’s uncertainty band. These results validate the effectiveness of the coupling strategy for enhancing plasma thruster simulation accuracy.

Impact of DBD Plasma Jet Treatment on the Enamel Surface of Primary Teeth.

The impact of cold atmospheric plasma (CAP) treatment on the enamel of twelve primary teeth (incisors, canines, and molars) collected from six children was examined in order to evaluate the possibility of using the CAP technique in dental applications. A radio-frequency dielectric barrier discharge (DBD) plasma jet operating at a voltage of 3.25 kV using a mixture of helium and oxygen as the working gas was used for the generation of plasma as part of the electro-technological method for the treatment of biological material. The plasma exposure time for the primary teeth was 5, 10, and 20 min. The properties of tooth enamel (color, contact angles, surface roughness, surface topography, elemental composition) were examined before (control) and after the plasma treatment. As shown by the results, the plasma treatment time is a key parameter that can induce desired features, such as whitening or improved wettability. However, with prolonged plasma treatment (20 min), the enamel surface may be permanently damaged. The cold-plasma-treated samples were characterized by a higher value of the brightness L* parameter and thus a lighter color, compared to the CAP-untreated teeth. It was also evidenced that the plasma treatment increased the hydrophilicity of tooth surfaces, and the contact angles effectively decreased with the time of the CAP treatment. The tooth surface also became much more heterogeneous and rough with much greater amplitudes in heights. The surface of the primary teeth after the CAP treatment lost its homogeneity, as evidenced by the SEM micrographs. The analysis of the elemental composition revealed only minor changes after the plasma process, which may suggest that the observed morphological changes in the enamel surface are mainly physical and are not a consequence of chemical reactions between the enamel and the reactive components of the cold plasma. Plasma treatment of teeth opens up new possibilities of using this method as an alternative to whitening or pre-treatment before other dental procedures.

Design, development and test of single beamlet microwave ion source with spot-dense plasma system

In this paper, an efficient ion source with unique characteristics is introduced and proposed. It outlines the generation of a spot-dense plasma just below the plasma electrode aperture of the extractor system through the utilization of a 2.45 GHz microwave plasma source with a power of 1000 W, in the absence of a magnetic field. This source utilizes a 2.45 GHz microwave plasma generator operating at 1000 W, resulting in the generation of a spot-dense plasma just below the plasma electrode aperture of the extractor system, all achieved without the need for a magnetic field.The spot-dense plasma results in the extraction of an ion beam with high current density. Furthermore, the suggested ion source can be utilized in a smaller size using a higher frequency. Therefore, our findings indicate that the proposed method not only substantially enhances the extracted positive ion beam current but also significantly reduces the size of the ion beam source system. Based on the design and simulation results, an experimental model of the ion beam source is constructed. The diagnostic tools provided the beam current density and system efficiency values of 99mA/cm2 and 7×10−6A/W, respectively.

Generation of low-temperature plasma by pulse-width modulated signals and monitoring of the interaction thereof with the surface of objects

Abstract The article discusses the use of pulse-width modulation signals to generate low-temperature at-mospheric plasma in an inert gas environment. The results of studies of the energy consumption of a low-temperature plasma generation system depending on the duty rate, as well as the pulse repetition rate, are presented. The operating modes of the system have been established, in which a minimum of energy consumption is achieved. The issues of evaluating the interaction of plasma with objects based on the analysis of changes in signal parameters in the high-voltage circuit of the generator are also considered.

Mechanism of cold atmospheric plasma in treatment of chronic skin ulcer

To review the mechanism of cold atmospheric plasma (CAP) in the treatment of chronic skin ulcer, providing a new idea for ulcer therapy. The literature about CAP in the treatment of chronic skin ulcers in recent years was extensively screened and reviewed. The treatment principle, active ingredients, and mechanism were summarized. CAP is partial ionized gas discharged by plasma generator in high frequency under high voltage. It contains electrons, positive and negative ions, reactive oxygen species, reactive nitrogen species, and ultraviolet rays. In vitro and animal experiments show that the active ingredients contained in CAP can inactive microorganisms, against biofilm, regulate immune-mediated inflammatory, promoting blood flow, stimulate tissue regeneration and epithelial formation in the course of wounds healing. CAP play a role in different stages of chronic skin ulcer healing, with good effectiveness and safety, and broad clinical application prospects. But more studies are needed to explore the indications and dosages of CAP therapy.

High-order harmonic generation in the laser-induced plasmas produced on the surfaces of transition metals (Rh, Ru, Nb, and Zr) from the fifth period of periodic table

High-order harmonic generation in the laser-induced plasmas produced on the surfaces of transition metals (Rh, Ru, Nb, and Zr) from the fifth period of periodic table

Impact of hot plasma effects on electron cyclotron current drive in tokamak plasmas

Abstract Focusing on the impact of hot plasma effects on electron cyclotron current drive (ECCD), this paper presents the numerical results of top launch ECCD (TL-ECCD) and outside midplane or equatorial-plane launch ECCD (EL-ECCD) in the HL-3-like tokamak plasmas. For EL-ECCD, there is little difference in the calculated results under the cold and hot plasma propagation models, and the results are not affected by the dominant current drive mechanism of EC waves. In the cases of TL-ECCD, the large initial parallel refraction makes the influence of hot plasma effects on ECCD become significant. In the range of toroidal magnetic fields BT discussed in this paper, the difference between the calculated results under the two propagation models rapidly decreases as the value of BT decreases, and the difference between the two is already very small in the range of 1.8 T ≤ BT ≤ 2.0 T. Therefore, the influence of hot plasma effects can also be neglected for TL-ECCD, and the cold plasma propagation model can be directly adopted. For the HL-3-like tokamak equipped with a dual-frequency EC wave system at 140 GHz and 105 GHz, if the addition of a TL-ECCD is considered in the existing outside midplane and upper launch manners, through appropriate combination of 140 GHz TL-ECCD and dual-frequency outside EL-ECCD, the ECCD can be used in a larger BT window (1.8 T ≤ BT ≤ 2.25 T) and a wider radial range (0.1 ≤ ρ ≤ 0.8 ~ 0.9) to generate current efficiently. The normalized current drive efficiency of the TL-ECCD is nonlinear with the injected EC power, it reaches the maximum at the injected power of 6 ~ 8 MW. This is of significance for the stable operation of HL-3-like tokamak with high plasma current above 1 MA.

Analytical and dynamical analysis of nonlinear Riemann wave equation in plasma systems

The Riemann wave equation presents appealing nonlinear equations applicable in sea-water and tsunami wave propagation, ion and magneto-sound waves in plasmas, electromagnetic waves in transmission lines, and homogeneous stationary media. This study focuses on deriving soliton solutions in optics and exploring their physical properties. A wave transformation is used to convert a partial differential equation into an ordinary differential equation, from which soliton solutions are obtained using the generalized Riccati equation mapping approach. The solutions encompass various types of solitons, including bright, dark, periodic, and kink solitons. A comparison of solutions from this analytical method enhances the understanding of the nonlinear model’s behavior, with implications in plasma physics, fluid dynamics, optics, and communication technology. Additionally, 2D and 3D graphs illustrate the physical phenomena of the solutions using appropriate constant parameters. The qualitative analysis of the undisturbed planar system involves examining phase portraits in bifurcation theory, followed by introducing an outward force to induce disruption and reveal chaotic phenomena. Chaotic trajectories in the perturbed system are detected through various plots, including 3D, 2D, power spectrum, and chaotic attractor, alongside Lyapunov exponents. Stability analysis under different initial conditions is conducted, and sensitivity assessments are performed using the Runge–Kutta method. The findings are innovative and have not been previously explored for this system, highlighting the reliability, simplicity, and effectiveness of these techniques in analyzing nonlinear models in mathematical physics and engineering.