Influence Of Plasma Parameters Research Articles

Growth of graphene nanowalls in low-temperature plasma: Experimental insight in initial growth and importance of wall conditioning

Plasma-enabled growth of vertically aligned graphene nanowalls (CNWs) and the influence of plasma parameters are widely investigated to produce high-quality CNWs. The initial growthsteps of CNWs and the impact of the plasma chamber condition still need to be explored. This work investigatesthe initial growth steps of CNWs and the influence of plasma chamber conditions using advanced spectroscopic and microscopic techniques. The changes in substrate surfaces and CNW growth were studied in two steps: pre-treatment and plasma deposition. Angle-resolved NEXAFS observations on the samples produced during both stages suggest that growth starts horizontallyon the substrate and changes to vertical in one critical moment. Also, we observed that CNW growth occurs not only at the deposition stage but also during the pre-treatment stage, indicating the influence of the chamber wall during the growth. Switching from horizontal to vertical orientation could be explained by the surface energy disbalance during the initial growth stages. The pre-treatment and conditioning of the chamber control the oxygen presence and provide a higher amount of carbon precursor for a fast, stable and controllable growth process. These results will direct the future possibilities of upscaling plasma systems for large-scale growth of CNWs for commercial applications by considering the influence of plasma and chamber conditions.

Bifurcation analysis of ion-acoustic superperiodic waves in ultra-relativistic dense plasma

Abstract Bifurcation analysis of ion-acoustic solitary, periodic and superperiodic waves in ultra-relativistic quantum degenerate electron-positron-ion plasma is investigated based on Sagdeev’s pseudopotential approach. The phase plane plots for the superperiodic, periodic, and homoclinic trajectories for the dynamical system are developed. Rarefactive and compressive solitary waves are demonstrated to exist. The influence of plasma parameters on the characteristic properties of the periodic and superperiodic waves is studied. Also, the effect of different plasma parameters on the Sagdeev pseudopotential profile is investigated. The results of this study may be used to shed light on the fundamental properties of nonlinear waves in dense objects (e.g., white dwarfs and neutron stars). These results also may be beneficial in describing laboratory plasma (e.g., interaction experiments of intense laser-solid matter), and plasma applications such as microelectronic devices.

Modulated ion-acoustic wavepackets in a multi-component dense plasma with Thomas-Fermi distribution

Modulated ion acoustic wavepackets have been investigated in a multi-component, dense plasma containing degenerate electrons/positrons, and positive/negative ions. The electrons and positrons assumed to be followed Thomas-Fermi distribution, while the ions considered to be classic. Employing a multi-scale perturbation technique, the nonlinear Schrödinger equation is derived. The criteria for the occurrence of modulational instability of the modulated ion acoustic waves are analyzed. The influences of plasma parameters on the modulational instability and its growth rate have been discussed. The envelope solitons have been discussed as well. The results showed that both modulationally unstable domain and stable domain can be found, depending on the plasma parameters. It is also found that the width of the envelop solitons are significantly modified by related plasma parameters. The present results will be useful in understanding the conditions for modulational instability of ion acoustic waves which are relevant to both space and laboratory dense plasmas.

Equivalent Circuit Model Analysis of Electromagnetic Metasurface Loaded With Plasma

An equivalent circuit model (ECM) is proposed for a Jerusalem cross metasurface structure loaded with plasma. Based on the microwave network theory, the electromagnetic properties of the composite structure are analyzed through this ECM. Due to the wave-absorbing effect of plasma, the parallel conductive and inductive elements are introduced to the ECM of the Jerusalem cross metasurface, forming the ECM of the composite structure. The circuit element parameters are extracted by genetic algorithm optimization. The consistency between the simulated reflection coefficient and the calculated ones by this model proves the accuracy of the proposed ECM for analyzing the electromagnetic properties of a composite structure. Moreover, the plasma collision frequency and the plasma electron density are selected within a certain frequency range to further prove the accuracy of this model. The influence of plasma parameters on the equivalent circuit element values is also analyzed. The ECM can predict the electromagnetic properties of the composite structure and provide theoretical guidance for the design.

MD Simulation of the Laser Effects on Stopping for B+ Ion in Plasmas

In this work, the laser effects on the stopping for boron ion in plasmas are studied by molecular dynamics (MD) simulation. The expressions of the stopping power is derived based on the potential. The effects of different laser intensity, laser frequency, laser angle, plasma density and electron temperature on the stopping power of B+ ion are discussed. The results tell that the stopping power of B+ ion will decrease significantly with the increase of laser intensity, and the laser intensity has a strong modulation effect on the stopping power. On the other hand, when the included angle between the laser and the moving direction of boron ion is in the range of 0 to π / 2, the stopping power decreases gradually with the increase of the projectile angle. On the other hand, the influence of plasma parameters on the stopping power of boron ions is also very obvious. When other parameters are given, the increase of plasma temperature or the decrease of plasma density can decrease the value of stopping power.

Plasma with carbon nanoparticles: advances and application

This article is devoted to the study of the glow intensity of radio-frequency capacitive discharge plasma with nanoparticles for further use in lighting devices. The process of carbon nanoparticles synthesis in the radiofrequency discharge was investigated, and the influence of plasma parameters on the formation and growth of the material was also studied. A method for determining the diameter of nanoparticles based on self-bias voltage and electron density is considered. It is revealed that the diameter of nanoparticles has a considerable influence on the optical properties of the plasma, in particular, on the emission intensity. Based on the obtained data, laboratory samples of lighting devices with improved luminous intensities were developed.

Influence of carbonaceous species entered during arc plasma synthesis on the stoichiometry of LaB6

Electron emission properties of lanthanum hexaboride are dependent on the crystal structure as well as stoichiometric ratio of boron and lanthanum. Present research deals with the influence of carbon diffusion on the stoichiometric LaB6 synthesized using arc plasma gas phase condensation process.Nanocrystalline LaB6 has been synthesized using arc plasma at different plasma powers viz 2–3.4 kW. Further, an inclusion of carbonaceous species from the graphite anode with increasing plasma power and its correlation with stoichiometry has been elucidated. X-ray photo-electron spectroscopic technique has been used for the identification of surface chemistry of the synthesized powders and more effectively to infer the stoichiometry i. e. ratio of B:La in the samples synthesized with increasing plasma in put power. The influence of plasma parameters on the work function of the synthesized nanoparticles has also been elucidated using Ultraviolet Photoelectron Spectroscopy (UPS).

Transmission characteristics of electromagnetic waves in a semicircular plasma filament layer generated by a femtosecond laser

AbstractThe transmission characteristics of electromagnetic (EM) waves in a semicircular plasma filament layer generated by a femtosecond laser were studied in a wide frequency band including radar waves. We have focussed on the influence of plasma parameters and filament arrangement based on the diffraction and superposition theory of EM waves on the transmittance. A numerical simulation model using the current density convolution finite‐difference time‐domain method was constructed in a semicircular multilayer filament structure, and the transmission characteristics of spherical EM waves were examined. The simulation results showed that in this semicircular structure, the transmittance was periodically changed at a frequency interval corresponding to the thickness of the filament channel. This phenomenon was more pronounced as the number of the filament layers increased. In the lower band (<30 GHz), there was little change in the transmittance according to layer‐to‐layer distance, but in the higher band (>30 GHz), it changed irregularly. On the contrary, for the electron number density, it changed regularly in the lower frequency and hardly changed in the higher frequency. When the number of layers was 3 or more, the transmittance became 0 at the centre of the channel, and a discontinuous interference pattern appeared more clearly as the frequency increased.

Nonlinear ion acoustic solitary waves with dynamical behaviours in the relativistic plasmas

This work investigates the basic features of Nonlinear Ion Acoustic Solitary waves (NIASWs) and their dynamical behaviours in an unmagnetized relativistic collisionless plasma system via the Schamel Korteweg-de Vries (SKdV) equation. Such plasma is composed by the generalized distributed electrons, Boltzmann distributed positrons and relativistic warm ions. The influences of plasma parameters on NIASWs and their dynamical behaviours are investigated by comparing 26−term expansion of relativistic Lorentz factor (RLF) with both of weakly (2−term expansion of RLF) and highly (3−term expansion of RLF) regimes. It is found that the 26−term expansion of RLF are significantly changed NIASWs instead of both weakly and highly relativistic regimes. Therefore, the theoretical results would be very useful for understanding the nature (amplitude, width, polarity, etc.) of wave dynamics not only in astrophysical and space environments but also in further laboratory studies, where the proposed plasma assumptions are existed.

Researches on the scattering characteristics in THz band of conductor cylinder coated with parabolic distribution and time-varying plasma media

It is widely acknowledged that inhomogeneous and time-varying plasma can effectively reduce the back scattering radar cross section (RCS) and THz wave has the potential to penetrate the plasma and against the plasma stealth. Therefore, the backscattering and bistatic radar cross section (RCS) of conductor cylinder coated with parabolic distribution and time-varying plasma media in THz wave band are studied by the Runge-Kutta Exponential Time Differencing-Finite Difference Time Domain (RKETD-FDTD) method in this paper. The influences of plasma parameters are analyzed. From both the backscattering and bistatic RCS simulations, it is obviously that inhomogeneous and time-varying plasma cloaking system makes a significant difference on reducing the RCS and improve the plasma stealth while electromagnetic wave in THz region can successfully weaken its influence and contribute to the anti-stealth.

Adhesion improvement at polyester fabric-silicone rubber interface by plasmas of argon and air to obtain conveyor belt

Conveyor belt production requires good adhesion between coating layer and fabrics. Adhesion is important for good mechanical properties of belts. Silicone rubber has gained importance in food carrying because it is harmless when being in contact with food materials. The aim of this study is to enhance the problematic adhesion properties between polyester fabrics and silicone rubber coating by plasma treatment. The fabrics are modified by air or argon RF plasmas under different power and time conditions. Influence of plasma parameters was investigated by adhesion strength tests. To investigate changes on adhesion, wettability measurements, X-ray photoelectron spectrometry (XPS), Atomic Force Microscopy (AFM), scanning electron microscopy (SEM) were performed untreated and plasma treated polyester fabrics. After plasma treatments, the coating adhesion between fabric and coating polymer was increased approximately for 4.6 times for argon and 4.3 times for air plasmas.

Controlled Surface Wettability by Plasma Polymer Surface Modification

Inspired by nature, tunable wettability has attracted a lot of attention in both academia and industry. Various methods of polymer surface tailoring have been studied to control the changes in wetting behavior. Polymers with a precisely controlled wetting behavior in a specific environment are blessed with a wealth of opportunities and potential applications exploitable in biomaterial engineering. Controlled wetting behavior can be obtained by combining surface chemistry and morphology. Plasma assisted polymer surface modification technique has played a significant part to control surface chemistry and morphology, thus improving the surface wetting properties of polymers in many applications. This review focuses on plasma polymerization and investigations regarding surface chemistry, surface wettability and coating kinetics, as well as coating stability. We begin with a brief overview of plasma polymerization; this includes growth mechanisms of plasma polymerization and influence of plasma parameters. Next, surface wettability and theoretical background structures and chemistry of superhydrophobic and superhydrophilic surfaces are discussed. In this review, a summary is made of recent work on tunable wettability by tailoring surface chemistry with physical appearance (i.e. substrate texture). The formation of smart polymer coatings, which adjust their surface wettability according to outside environment, including, pH, light, electric field and temperature, is also discussed. Finally, the applications of tunable wettability and pH responsiveness of polymer coatings in real life are addressed. This review should be of interest to plasma surface science communality particularly focused controlled wettability of smart polymer surfaces.

Characteristics of electromagnetic wave transmission and reflection from isotropic plasma coated circular nihility cylinder

Theoretical investigation has been carried out to study the scattering and transmission of electromagnetic energy from isotropic plasma coated circular nihility cylinder. The physical modeling of the problem is done in frame work of classical scattering theory. All the fields are expanded in terms of cylindrical vector wave functions (CVWFs). The analytical as well as numerical solution for both Transverse Electric (TE) and Transverse Magnetic (TM) polarizations is presented. The unknown scattering coefficients are computed by implementing the boundary conditions at each interface (free space/plasma and plasma/nihility). The influence of plasma parameters i.e., plasma density (ND) and effective collision frequency (v) on the bistatic echo width is analyzed and it is concluded that the plasma coating can be used to control and tune the scattering amplitude. Further it is also concluded that for the case ω > ωp the scattering amplitude is much less than for the case ω < ωp. Under special conditions, the results of present work compared with the published literature and good agreement is found.

Parametric investigation of symmetric electromagnetic waves propagating along inhomogeneous plasma layer coated metallic surfaces

Based on the transcendental dispersion relation of the azimuthally symmetric mode which propagates along the surface of an inhomogeneous and collisional plasma layer coated cylindrical metallic surface, the influence of plasma parameters and metallic surface geometric size on propagation constant, radiation enhancement intensity, and wave energy loss properties is investigated. Theoretical calculation results indicate that there is a resonance at the point ωpe/ω = 1; near this point, the propagation constant of the symmetric mode exhibits extraordinary characteristics, the radiation enhancement intensity reaches a maximum at the point (ωpe/ω = 1.05, ν/ω = 1), and the wave energy loss reaches a maximum at the point (ωpe/ω = 1, ν/ω = 0.006). These theoretical results may have a potential application value in microwave enhanced radiation and high resolution image processing.

Investigation of the influence of pretreatment parameters on the surface characteristics of amorphous metal for use in power industry

Metallic glasses are metallic materials, which exhibit an amorphous structure. These are mostly three or more component alloys, and some of them are magnetic metals. Materials of this kind are characterized by high electrical resistivity and at the same time exhibit very good magnetic properties (e.g. low-magnetization loss). The above mentioned properties are very useful in electrical engineering industry and this material is more and more popular as a substance for high-efficiency electrical devices production. This industry area is still evolving, and thus even higher efficiency of apparatus based on amorphous material is expected. A raw material must be carefully investigated and characterized before the main production process is started.Presented work contains results of complementary examination of amorphous metal Metglas 2605. Studies involve two ways to obtain clean and oxidized surface with high reactivity, namely degreasing followed by annealing process and plasma treatment. The amorphous metal parameters were examined by means of several techniques: surface free energy (SFE) measurements by sessile drop method, X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and both ex situ and in situ Raman spectroscopy. Additionally, influence of plasma parameters on wetting properties were optimized in systematic way with Design of Experiments (DOE) method.A wide range of used methods allow to fully investigate the amorphous metal material during preliminary preparation of surface. Obtained results provide information about appropriate parameters that should be applied in order to obtain highly reactive surface with functional oxide layer on it.

Nonlinear propagation of ion-acoustic waves through the Burgers equation in weakly relativistic plasmas

The Burgers equation is obtained to study the characteristics of nonlinear propagation of ionacoustic shock, singular kink, and periodic waves in weakly relativistic plasmas containing relativistic thermal ions, nonextensive distributed electrons, Boltzmann distributed positrons, and kinematic viscosity of ions using the well-known reductive perturbation technique. This equation is solved by employing the (G'/G)-expansion method taking unperturbed positron-to-electron concentration ratio, electron-to-positron temperature ratio, strength of electrons nonextensivity, ion kinematic viscosity, and weakly relativistic streaming factor. The influences of plasma parameters on nonlinear propagation of ion-acoustic shock, periodic, and singular kink waves are displayed graphically and the relevant physical explanations are described. It is found that these parameters extensively modify the shock structures excitation. The obtained results may be useful in understanding the features of small but finite amplitude localized relativistic ion-acoustic shock waves in an unmagnetized plasma system for some astrophysical compact objects and space plasmas.

Nonlinear propagation of weakly relativistic ion-acoustic waves in electron–positron–ion plasma

This work presents theoretical and numerical discussion on the dynamics of ion-acoustic solitary wave for weakly relativistic regime in unmagnetized plasma comprising non-extensive electrons, Boltzmann positrons and relativistic ions. In order to analyse the nonlinear propagation phenomena, the Korteweg–de Vries (KdV) equation is derived using the well-known reductive perturbation method. The integration of the derived equation is carried out using the ansatz method and the generalized Riccati equation mapping method. The influence of plasma parameters on the amplitude and width of the soliton and the electrostatic nonlinear propagation of weakly relativistic ion-acoustic solitary waves are described. The obtained results of the nonlinear low-frequency waves in such plasmas may be helpful to understand various phenomena in astrophysical compact object and space physics.

Effect of glow discharge oxygen plasma treated surface and antimicrobial properties of viscose fabric

In this paper, an effective and clean production process was developed for spandex mixed viscose fabric pretreatment with the aid of low pressure plasma. The functional properties are developed due to plasma treatment. The influence of plasma parameters, such as oxygen pressure, discharge power and exposure time of pretreatment, on the fabric was investigated and compared with aloe vera and ZnO coated fabric. Results reveal the weight loss, impurity removal, contact angle and antimicrobial properties of the fabric. Modification of the chemical nature of the fabric surface was characterised by ATR-FTIR, the study of the surface morphology by scanning electron microscopy.

Influence of plasma parameters and substrate temperature on the structural and optical properties of CdTe thin films deposited on glass by laser ablation

In the pulsed laser deposition of thin films, plasma parameters such as energy and density of ions play an important role in the properties of materials. In the present work, cadmium telluride thin films were obtained by laser ablation of a stoichiometric CdTe target in vacuum, using two different values for: substrate temperature (RT and 200 °C) and plasma energy (120 and 200 eV). Structural characterization revealed that the crystalline phase can be changed by controlling both plasma energy and substrate temperature; which affects the corresponding band gap energy. All the thin films showed smooth surfaces and a Te rich composition.

Improving adhesion of powder coating on PEEK composite: Influence of atmospheric plasma parameters

In aeronautic industries, powder coatings are increasingly used because of environmental considerations. During the deposition of such a coating on a substrate piece, the main objective is to obtain a good coating/substrate adhesion. In this study, the targeted substrate is a Poly-(Ether EtherKetone)-(PEEK) based composite material. Due to the poor surface energy of PEEK, a surface treatment is necessary in order to enhance its adhesion with the coating. In this purpose, atmospheric plasma treatment has been chosen and the influence of plasma parameters has been studied. Four scan speed nozzles and three gases (Air, N2 and Argon) plasma has been tested. The increase of adhesion with increasing wettability, polarity and nanoroughness has been evidenced. A particular study of the type of grafted polar functionalities according to gas nature allowed to better understand the plasma mechanism and the cross-impact of polarity and nanoroughness in adhesion enhancement.