Influence Of Electron Temperature Research Articles

Surface activation of thin polyvinyl alcohol films by atmospheric pressure plasma jet: Influence of electron temperature

AbstractThis study investigates the effects of nonthermal plasma characteristics on surface treatments of polyvinyl alcohol with various diagnostics such as Raman spectroscopy, work of adhesion, optical emission spectroscopy, and current–voltage measurements. Our findings demonstrate the importance of controlling the plasma's electron temperature and density to achieve the desired surface treatment outcomes. We show that plasma jets with varying electron temperatures are more appropriate for different surface treatments, with high electron temperatures than 1.1 eV suitable for functional group (C═O) insertion abiding macro‐scale surface roughness and low electron temperatures for plasma etching, which increased surface roughness significantly. Plasma electron temperatures between 1.1 and 1.3 eV are best for treatment as higher ones cause bond breaking while lower ones would etch the surface.

Studies of growing waves in Hall thruster beam plasma under the influence of electron temperature

Studies of growing waves in Hall thruster beam plasma under the influence of electron temperature

Numerical study on the influence of electron temperature on void formation in dusty plasma

In the past, experiments have proven that the electron temperature in the void is lower than that in the dust cloud. Based on this point, the influence of the spatial distribution of the electron temperature on the void is studied by calculating the fluid equation with explicit ionization, and the images of the circular void and the ring void are obtained by simulation. It is found that when the electron temperature is greater than the threshold value, a stable circular void is generated, and as the electron temperature increases, the time required for the circular void to reach a steady state decreases and its size decreases. This law is not affected by electron temperature spatial distribution set in the center. Combined with the studies of circular void, we speculate that the electron temperature in the ring void is also lower than that in the dust cloud. Through the assumption of the spatial distribution of electron temperature, the simulation results in a ring-shaped void. And the influence of the intensity of the spatial variation of the electron temperature on the ring void is verified. The results show that when the electron temperature change is severe enough, a ring void is generated. And as the intensity increases, the time required for the ring void to reach a steady state decreases, and the size increases slightly.

Influence of electron temperature on breaking of plasma oscillations

Abstract The influence of thermal motion of electrons on the processes of relativistic plasma oscillations is studied analytically and numerically. It is shown that if the temperature of electrons grows and exceeds a certain critical level, then the breaking effect vanishes due to transformation of plasma oscillations into travelling waves. Analytical conclusions are made in the framework of the theory of small perturbations based on Lagrangian variables. Numerical simulation of the transformation is performed using three different algorithms constructed on the basis of the method of finite differences in Eulerian variables. The analytical results are in good agreement with numerical experiments.

Characteristics of carbon-related materials deposited in electron-energy controlled CH 4/H 2 RF discharge plasmas

The influence of electron temperature T e on the production of carbon-related materials was investigated in a hollow-type magnetron radio-frequency (RF) CH 4/H 2 plasma. Here, the electron temperature decreased along the plasma column. Since the dissociation of CH 4 is determined by the electron energy in plasmas, the density ratio of radicals CH 2/CH 3 can be varied by the electron temperature. Therefore, the change of the electron temperature is quite important for controlling the characteristics of carbon-related materials. In the experiment, the production of diamond microparticles in low T e plasma was detected. On the other hand, thin carbon films consisting of graphitic carbons were observed in the high T e plasma. Therefore, it is shown that control of the electron temperature in the plasma has a key effect on the film quality.

A sodium (Na) beam edge diagnostic

A fast (40–80 keV) neutral sodium (Na) beam is considered as advantageous alternative to the fast lithium (Li) beam installed at ASDEX Upgrade. Recently, a complete data set of all relevant plasma particles (electron, ions) – Na collisions has been compiled [1] and first experiments with a Na beam installed at ASDEX Upgrade have been carried out. A collisional radiative model is employed to calculate the beam attenuation in a plasma discharge as well as the occupation number of Na excited states (including n = 3, 4, 5s). Excellent agreement between modeled and measured Na I emission profiles is found, proving the validity of the compiled data set. Despite the lower velocity at the same acceleration voltage, beam penetration of Na as compared with Li is not significantly deteriorated. The influence of electron temperature ( T e) and Z eff profiles on evaluated electron density ( n e) profiles is analyzed.

Filtration of Interstellar Atoms through the Heliospheric Interface

Interstellar atoms penetrate deep into the heliosphere after passing through the heliospheric interface—the region of the interaction of the solar wind with the interstellar medium. The heliospheric interface serves as a filter for the interstellar atoms of hydrogen and oxygen, and, to a lesser extent, nitrogen, due to their coupling with interstellar and heliospheric plasmas by charge exchange and electron impact ionization. The filtration has great importance for the determination of local interstellar abundances of these elements, which becomes now possible due to measurements of interstellar pickup by Ulysses and ACE, and anomalous cosmic rays by Voyagers, Ulysses, ACE, SAMPEX and Wind. The filtration of the different elements depends on the level of their coupling with the plasma in the interaction region. The recent studies of the filtration of the interstellar atoms in the heliospheric interface region is reviewed in this paper. The dependence of the filtration on the local interstellar proton and H atom number densities is discussed and the roles of the charge exchange and electron impact ionization on the filtration are evaluated. The influence of electron temperature in the inner heliosheath on the filtration process is discussed as well. Using the filtration coefficients obtained from the modeling and SWICS/Ulysses pickup ion measurements, the local interstellar abundances of the considered elements are determined.

Consecutive- reversible Iioniza-tion-recombination rReactions and Iionic Ccharge sState dDistribution of Au plasma

The present work proposes kinetics of ionization-recombination to carry out a research intostudy the charge state distribution of Au plasma. The first step is to calculate the average lifetime, energy level structure, degeneracy and partition function of Au 48+ ―Au 52+ by relativistic quantum mechanics, and next to compute then, the equilibrium constant and the second-order recombination rate constant by statistical thermodynamics. Based on these data, the solution of differential equations of consecutive- reversible ionization-recombination reactions are solved from whichlead to the charge state distribution and its average charge are derived. FinallyWe do not only give the average charge, but also derive the quantitative influence of electron temperature and density on average charge by electron temperature and electron densityis given in this paper. It is called the first-principles theory, for no experimental data is are needed.

Carbon content control in plasma carburizing using process parameter and probe methods

Low carbon steel foil specimen was plasma carburized in methane/hydrogen mixed gas. In this study carbon content was controlled using process parameter and probe methods. As the plasma current, plasma voltage and/or treating time increases, the carbon content increases. An equation, by which carbon content was accurately estimated with respect to process parameters, was obtained. Using this equation along with variables such as treating time, plasma current and plasma voltage, the carbon content can be predicted using the treating parameters. In the plasma carburizing process, the influence of electron temperature and electron density measured by the Langmuir probe, on carbon content was studied on low carbon steel foils of 0.25 mm in thickness. Increases in plasma current and plasma voltage lead to decrease in electron temperature. The carbon content decreases curvilinearly as the electron temperature increases.

The Influence of Electron Temperature and Magnetic Field Strength on Cosmic‐Ray Injection in High Mach Number Shocks

Electron preacceleration from thermal to mildly relativistic energies in high Mach number shocks (the injection problem) is an outstanding issue in understanding synchrotron radiation from supernova remnants. At high Alfvenic Mach numbers, collisionless perpendicular shocks reflect a fraction of the upstream ions. This gives rise to two-stream instabilities, which in turn can accelerate ions. However, in astrophysical plasmas, the value of β—the ratio of kinetic pressure to magnetic pressure—is not well known. We have used a particle in cell simulation code to investigate the influence of β on the shock structure and on the electron acceleration (assuming thermodynamic equilibrium in the undisturbed plasma, β = βi = βe). Previous simulations at low values of β showed that the phase space distributions of electrons and ions became highly structured: characteristic holes appear in the electron phase space, and the shock dynamics exhibit reformation processes. However, we find that all these features disappear at higher β due to the high initial thermal velocity of the electrons. It follows that the electron cosmic-ray injection mechanism depends strongly on β, that is, on the electron temperature normalized to the magnetic field upstream.

The influence of electron temperature on pattern-dependent charging during etching in high-density plasmas

The effect of the electron temperature (Te) on charging potentials that develop in trenches during plasma etching of high aspect ratio polysilicon-on-insulator structures is studied by two-dimensional Monte Carlo simulations. Larger values of Te cause the potential of the upper photoresist sidewalls to become more negative; thus, more electrons are repelled back and the electron current density to the trench bottom decreases. The ensuing larger charging potential at the bottom surface perturbs the local ion dynamics so that more ions are deflected towards the polysilicon sidewalls causing (a) more severe lateral etching (notching) and (b) larger gate potentials, thereby increasing the probability of tunneling currents through the underlying gate oxide. The simulation results capture reported experimental trends and offer new insight into the nature of charging damage.

INFLUENCE OF ELECTRON TEMPERATURE ON POPULATION INVERSION AMONG ELECTRONIC SUBBANDS IN OPTICALLY PUMPED SEMICONDUCTOR QUANTUM WELLS

A detailed theoretical study on population inversion among different electronic subbands, induced by hot-electron interactions with LO-phonons and with photons, is presented for an optically pumped AlGaAs-GaAs double quantum well system which may behave as a 3-level far-infrared laser generator. The influence of electron temperature and pumping intensity on the population inversion in this laser system proposed very recently, has been studied through calculating the inter-subband electronic scattering rate caused by electron-LO-phonon interactions and by optical absorption scattering. Theoretical results obtained from this study indicate that at a fixed pumping intensity, the population inversion among different electronic subbands can be tuned by varying electron temperature through, e.g. applying an in-plane electric field.

低炭素鋼のプラズマ浸炭における炭素濃度制御へのプローブ診断法の適用

In the plasma carburizing process, the influence of electron temperature and electron density measured by a langmuir probe on carbon content was studied on low carbon steel foils of 0.25 mm in thickness. The increases in plasma current and plasma voltage cause the decreases in electron temperature. The carbon content decreases curvilinearly as the electron temperature increases. Generally the carbon content approximately 0.8 mass% is targeted to obtain an effective mechanical property. But the decreasing rate of carbon content to electron temperature at around 0.8 mass%C is large, so a highly accurate control with electron temperature is difficult. The increase in plasma current and plasma voltage cause the increases in electron density. The carbon content increases linearly as electron density increases. Negative charges balance with positive charges in plasma, so the density of positively charged carbon ions increases as the electron density increases, hence the carbon content increases. Even if the electron temperature or electron density is constant, the carbon content increases as the premixed methane ratio increases. Because the increase in premixed methane ratio causes the increased retained methane ratio and the increased carbon potential. Even if the plasma current or plasma voltage changes in plasma carburizing, the carbon content can be predicted and controlled by the electron density.

Influence of electron temperature and carrier concentration on electron–LO-phonon intersubband scattering in wide GaAs/AlxGa1−xAs quantum wells

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