bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ionization Equilibrium in Nonideal Alkali and Noble Gas Plasmas
Authors: Redmer R. , Rother T. , Schmidt K. , Kraeft W. D. , Röpke G. 
Published: July 2007

AbstractUsing the method of thermodynamic Green functions, a generalized Saha equation is derived which accounts for different non‐ideality effects, as, e. g., interaction between charged particles and neutral composites (atoms). The degree of ionization was calculated for the alkali metals Li—Cs and for Xe in a wide n‐T range. Furthermore, the chemical potential μ and the pressure p were determined for these elements.
Generalized Susceptibilities for a Wall‐Stabilized Electric Are Displacement
Authors: Ramos‐Barrado J. R. , Galán‐Montenegro P. 
Published: July 2007

AbstractComplex susceptibilities for are displacement produced by an intermittent HF irradiation or by a time‐dependent transverse magnetic field, are defined. The analytical character of these susceptibilities is established from the development of its Kramers‐Kronig relations. Some experimental results for an are in a transverse magnetic field are shown.
The Impact of Different CO Admixtures on the Electron Kinetics in Collision Dominated RF He/CO Bulk Plasmas
Authors: Dilonardo M. , Capitelli M. , Gorse C. , Wilhelm J. , Winkler R. 
Published: July 2007

AbstractElectron energy distribution functions and mean collision frequencles for the uniform bulk plasma of established rf discharges in He/CO have been obtained by solving the time dependent Boltzmann equation. The results, which are of importance for plasma processing and laser technology, show that already small CO admixtures to He remarkably changes the periodic behaviour of the energy distribution of the electrons by drastical enhancement of the collisional energy dissipation effectiveness in the mixture. These changes can be interpreted on the basis of a lumped energy dissipation frequency in all electron collisions which is determined by the atomic data of the electron collision processes as well as by the admixture fractions and which drastically increases with increasing CO admixture. The degree of modulation of the energy distribution in different parts of the electron energy space and its population on the time average at higher energies are determined by the relation between the rf field frequency and the mentioned lumped energy dissipation frequency.
Burning Voltage in Atmospheric and Vacuum Short Arcs of Vanishing Length
Authors: Vogel N. 
Published: July 2007

AbstractThe stepwise increase of the burning voltage of short break arcs has been found not only in a gas but also in vacuum. It is suggested that the effect is associated with the occurrence of a positive anode fall which enhances ionisation phenomena near the anode. This view is supported by the simultaneous registration of arc current, burning voltage, light emission from the anode region, of spectral lines of ions, atoms and continuum from the near anode plasma. The phenomena occur beyond a critical gap distance which can be related to the characteristic geometry of the discharge.
Vortex Flows Induced by Electric Arc
Authors: Engelsht V. S. , Nevelev D. V. , Zhajnakov A. 
Published: July 2007

AbstractIn this paper a mathematical model of the stationary electric arc is made on the basis of solution of radiation gas dynamics two‐dimensional equations. Numerical analysis of electric arc with small length, depending on current force, distance between electrodes, electrode behaviour and geometry, type and expenditure amount of plasma forming gas, is carried out. It is shown that under some definite conditions electric arc induces toroidal gas vortexes playing an important part in the process of heat and mass transfer in electric arc plasma.
A Second‐Order Theory for Electron Plasma Solitary Waves in a Cylindrical Waveguide
Authors: Ghosh B. 
Published: July 2007

AbstractTo describe the long time asymptotic behaviour of weakly nonlinear plasma waves propagating in a strongly magnetized plasmafilled cylindrical waveguide the usual KDV equation which is first order in wave amplitude is extended to second order including the effects of finite temperature, mobile ions and giving a proper treatment to the radial co‐ordinate for all possible modes of propagation. The second‐order effects on the first‐order solitary wave profile, phase speed and first order correction to the wavelength are all determined and discussed.
Basic Mechanisms in Plasma Etching
Authors: Deutsch H. , Kersten H. , Rutscher A. 
Published: July 2007

AbstractA summary is given on the temperature dependence and basic processes in dry etching. The basic processes as Physical and Chemical Sputtering and Surface Film Etching completed by ion or electron stimulation of gas‐surface reactions and combined with adsorption and desorption are used in modelling different types of etch characteristics. Of special interest are non‐monotoneous characteristics. For some typical examples a comparison between measured and calculated curves is given which permit the determination of some kinetic parameters as activation energies and residence times.
Effects of Trapped Ions on the Nonlinear Propagation of Modified Electron Acoustic Waves
Authors: Das U. N. , Goswami K. S. , Bujarbarua S. 
Published: July 2007

AbstractEffects of trapped ions on the nonlinear propagation of modified electron acoustic waves in an unmagnetized plasma consisting of one cold and one hot components of electrons and one single species of hot ions, have been investigated in this paper. It has been shown that while rarefactive soliton solution exists in such a plasma, no double layer solution has been found to exist. The potential, velocity and width of the soliton have been calculated.
Determination of NIP‐Parameters in Terms of the Scattering Spectra Integral Characteristics
Authors: Adamjan V. M. , Tkachenko I. M. 
Published: July 2007

AbstractA new plasma diagnostics method is described, based on the connection between equilibrium plasma parameters (density, temperature, electronic static local field correction, static dielectric permeability, etc.) and the frequency moments of laser scattering and electron‐energy loss spectral intensities.
Hβ‐Line Profile Measurements in Optical Discharges
Authors: Uhlenbusch J. , Viöl W. 
Published: July 2007

AbstractIn the electrical field of a focused beam of a high‐power DC discharge multikilohertz repetition rate Q‐switched CO2 laser a so called pulsed optical discharge (POD) can be sustained. Applying laser pulses with max. 104 pulses/s, 50 mJ/pulse, pulse length 0.2 μs, average power 500 W and peak power 250 kW, the charge carrier density of a hydrogen plasma at a pressure of several MPa produced during the laser pulse is enhanced up to about the cut‐off density at λL = 10.6 μm (≃ 1025 m−3) and the electron temperature is increased to about 105 K. The non‐ideality factor reaches about 0.2. The calibrated line intensity of the Balmer Hβ was monitored by means of an optical multichannel analyzer system with spatial, frequency and time resolution. The measurements yield Stark‐broadened Hβ‐line profiles from which, assuming partial local thermal equilibrium, the electron temperature and density can be derived. The measured asymmetry of the Hβ‐line is in rough agreement with theoretical predictions available in literature.
Stark Shift and Broadening of Hydrogen Spectral Lines
Authors: Günter S. 
Published: July 2007

AbstractA Green's function approach as a many‐body treatment of the optical properties of dense plasmas is used to calculate profiles of Lyman‐α and Balmer‐α lines of hydrogen. The electron collisions are treated by an impact‐approximation. Because of a fully quantum mechanical treatment of electron collisions the integrals for shift and width do not diverge. In spite of that, we have to cut off these integrals because of an overestimation of the strong collision contributions. Effects of ions are incorporated into the Green's function concept in a quasistatic approximation using Hooper's distribution functions.
Reflectivity of Dense Plasma
Authors: Mintsev V. B. , Zaporogets Yu. B. 
Published: July 2007

AbstractThe results of the measurements of the reflection coefficient of the laser beam with λ = 1.06 μm from dense xenon plasma at P = 1.6–17 GPa and silicon under shock loading up to the insulator‐metal transition region at P = 10‐‐46 GPa are presented. Some properties of the optical and explosive experimental setup are described. The reflection picture and comparison of the dense plasma models with the experimental data are discussed.
The Regular Truncation Scheme of the BBGKY Hierarchy Equations for the Multi‐Component Weakly Non‐Ideal Plasma
Authors: Shapiro M. M. , Parsadanyan S. M. , Tabachnik Yu. V. , Furgel I. A. , Golosov N. S. 
Published: July 2007

AbstractA regular truncation scheme in which the divergencies characteristic of the Debye truncation are removed by taking into account the shall‐range correlations. As a result, the two radii of screening the Debye radius D and √2 D appear in plasma which is not symmetrical as to its particle charges. The criterion of the applicability of this approach relates the plasma parameter to the potential depth of unlike‐charged particles interaction.
TOkamak Edge Studies with A 2D Multifluid Code
Authors: Neuhauser J. , Braams B. , Krech M. , Ritschel U. , Schneider W. , Wunderlich R. 
Published: July 2007

AbstractThe Garching version B2CODE87 of the multifluid tokamak edge code of B. Braams is used for edge scoping studies in a quadrupole‐type x‐point geometry representative for open divertor configurations like ASDEX‐Upgrade or ITER. Two selected topics of common interest are treated here: Edge density limit in comparison with analytic models and impurity transport in the edge region. With respect to impurity transport the results of simpler models are qualitatively recovered for various nickel source scenarios. On the other hand, the simple edge density limit predicted by analytic models for pure hydrogen plasma is not recovered. Including impurity radiation, a modified limit is obtained.
MOdelling of Impurity Generation and Transport in Scrape‐Off Layers
Authors: Kawamura T. , Ono T. , Yoshida H. 
Published: July 2007

AbstractThe scrape‐off layer plasma is simulated with a 2‐dimensional fluid plasma code (SLIM) and a Monte Carlo neutral transport code (DEGAS) where the two codes are made runs iteratively until almost stable results are obtained. The geometry of the scrape‐off layer is referred to a toroidal pump limiter system. In the scrape‐off plasma thus obtained, ionization of neutral impurity particles ejected from the first wall, drift motion of charged impurities along the magnetic field lines and random diffusion across the magnetic field lines are simulated by a Monte Carlo method using atomic reaction rates of relevant processes and transport coefficients in the scrape‐off layer. From the statistics on calculations of destination of many impurity particles, the screening efficiency of the scrape‐off layer for impurity penetration into the core plasma, the impurity redeposition rate on the first wall, the exhaust efficiency of impurities are quantitatively analyzed.
Stationary Study of the Boundry Plasma of Large Tokamaks with Divertor
Authors: Galkowski A. , Zagorski R. 
Published: July 2007

AbstractThe hydrogen plasma and impurity flows parallel to the magnetic field lines in a collissional tokamak scrape‐off layer are numerically investigated. The physical model is developed on the basis of electron‐ion fluid equations for hydrogen plasma and rate equations for impurities. A complex model valid for arbitrary concentration of impurity ions based on 21‐moment Grad approximation is used to describe transport coefficients and thermal forces. Plasma interactions with neutral particles recycling at the divertor plate are taken into account. Steady state spatial profiles of the plasma and impurity (0, C) parameters are computed using the time relaxation method Possibility of helium exhaust is investigated.
The use of Langmuir Probe Methods for Plasma Diagnostic in Middle Pressure Discharges
Authors: David P. , Sicha M. , Tichy M. , Kopiczynski T. , Zakrzewski Z. 
Published: July 2007

AbstractThe article attempts to summarize the most important knowledge about the analysis of a Langmuir probe at middle pressures. First it briefly reviews the recent theories which deal with interpretation of Langmuir probe data at such conditions and then it applies the theory to the measurements in a Neon discharge at pressures 1.86 and 2.46 kPa. The charged particle density and the electron temperature obtained from the same probe data using different theories is compared against each other and a satisfactory agreement is obtained. The recommended procedure of probe data interpretation is given at the end of the paper.
Propagation of a Surface Wave Sustaining a Plasma Column at Atmospheric Pressure
Authors: Moisan M. , Pantel R. , Hubert J. 
Published: July 2007

AbstractThe propagation of a microwave surface wave is observed along a filamentary argon plasma at atmospheric pressure. The plasma is completely sustained by the propagating wave. Although the collision frequency is about ten times the wave angular frequency, the electron density is high enough so that the resulting conductivity of the plasma filament permits the propagation of the surface wave. The wave dispersion and attenuation diagrams calculated using a cold plasma linear dielectric description are in relatively good agreement with the experimental results.
Kinetic Approach to Reaction and Diffusion in Many‐Particle Systems
Authors: Klimontovich Yu. L. , Schlanges M. , Bornath T. 
Published: July 2007

AbstractA derivation of hydrodynamic equations which describe diffusion in connection with reaction processes in many‐particle systems is given on the basis of quantum kinetic theory. For this purpose kinetic equations are derived for a quantum gas with chemical reactions. Following Grad's method in a linear approximation reaction‐diffusion equations can be obtained with explicite expressions for the diffusion and reaction rate coefficients. The influence of nonideality effects in reaction‐diffusion equations is discussed.
Parametric Excitation of Electron‐Acoustic Mode in a Plasma of Two‐Temperature Electrons
Authors: Dwivedi C. B. , Asthana Meenu , Guha S. 
Published: July 2007

AbstractUsing hydrodynamical model of the two‐electron‐temperatere plasma, the analytical investigation of parametric instability of electron‐acoustic wave has been made. It is found that the growth rate decreases with increasing concentration ratio of the hot to the total electrons nh0/n0. The growth rate is found to be more for
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On a New Method of Determining Collision Rates for Ionization by Means of Pair Collisions and Stepwise Ionization
Authors: Wilke C. , Kablan N. , Deutsch H. 
Published: July 2007

AbstractWe report on a new method to determine the collision rates for ionization by means of pair collisions (Paarstöße) and stepwise ionization, respectively. This method is based on the experimental and theoretical study of the dynamical behaviour (impedance behaviour) of the positive column of a low‐current discharge at low pressure.
Absolute Electron Impact Cross Sections for Single Ionization of Metastable Atoms of H, He, Ne, Ar, Kr, Xe and Rn
Authors: Margreiter D. , Deutsch H. , Märk T. D. 
Published: July 2007

AbstractCross sections for single ionization of metastable atoms of H, He, Ne, Ar, Kr, Xe and Rn by electrons with impact energy E (threshold < E < 200 eV) are determined using a recently developed semiclassical formula. The formula consists of an energy dependent term (classical binary encounter approximation) and a term containing the weighted sum of the squared radii of maximum charge density of the outer electron subshells (Born Bethe approximation). Although this formula was originally devised and applied for ground state atoms, a comparison of the present calculations with previous calculations and measurements indicates that this formula can also be used successfully in case of metastable atoms.
Stationary Striations due to Interaction of Two Ionization Waves in Xenon Glow Discharge
Authors: Maruyama T. , Nishina S. , Kitamura H. , Itagaki K. , Mizuochi H. 
Published: July 2007

AbstractExperimental observations on stationary striations in the positive column of xenon discharge are reported. Stationary striations are observed when two ionization waves exist simultaneously in the positive column at low pressure and high current region. These stationary striations are caused by nonlinear interference of two backward ionization waves of which frequencies are either equal or are in the ratio 1:2. The spatial intervals for the striated pattern are equal to the reciprocal of the difference between the wave‐numbers of two ionization waves.
Statistics of Ignition Processes in ac Plasma Displays
Authors: Roepcke J. , Zahn R.‐J. 
Published: July 2007

AbstractThe statistics of the ignition behaviour of discharge cells in ac plasma displays and interaction processes occurring between several ignited cells are described and interpreted with a view to basic problems of gas discharge and solid state physics. For the statistical evaluation of ignition lag values recorded by means of a computer controlled equipment the Laue distribution is used.
MAgnetically Stabilized Plasma Sources of Getter Films
Authors: Karpov D. , Saksagansky G. 
Published: July 2007

AbstractModern state and ways of development of getter film plasma sources with the magnetic stabilization (GFPS) are considered. The description of physical mechanism of the magnetic stabilization, GFPS constructions and technical characteristics, their confronting parameters and the main factors defining usage perspectives is presented.
Model Experiments on Study of the First Wall Erosion Under the Action of Vacuum Arcs
Authors: Karpov D. , Saksagansky G. , Paszti F. 
Published: July 2007

AbstractWith d. c. vacuum arc discharges the dependence of cathode erosion rate on the transverse magnetic field induction is non‐linear. At first erosion rate rises with the magnetic induction and then drops. The maximum erosion rate value corresponds to the magnetic induction interval (50 – 115) · 10−4 T. The range of the vacuum arc discharge maximum stability also corresponds to the same interval. When the magnetic induction rises from 2 · 10−3 up to 1.1 · 10−2 T (I = 50 A), the erosion products angular distribution monotoneously narrows and with further magnetic ficld enhancement it abruptly widens. Current rise results in increasing extension of erosion products angular distribution. Asymmetry of erosion products angular distribution does not depend on the direction of the magnetic induction vector and gradually vanishes when the magnetic induction rises up to 1 · 10−2 T and higher.
ELectron Collision Rates and Transport Coefficients of a Weakly Ionized dc Plasma in Ar/Sih4‐Mixtures
Authors: Pfau S. , Winkler R. 
Published: July 2007

AbstractThe paper deals with electron kinetics of a Ar/SiH4 dc plasma, using the stationary and spatially uniform Boltzmann equation. The solution of this kinetic equation has been obtained by applying higher order Legendre polynomial expansion of the electron velocity distribution. For varying mixture composition the energy distribution and relevant macroscopic quantities as mean energy, drift velocity, rate coefficients for excitation, dissociation and ionization and relevant energy transfer rates for these processes have been calculated. In particular, it has been found that a most effective activation of the feed gas occurs for SiH4 admixtures in the range from 5 to 10 per cents.
New Method for Determination of Excited State Lifetime
Authors: Becker W. , Behnke J. , Kagel H. , Leven R. 
Published: July 2007

AbstractThe use of optical methods for the detection of plasma waves requires the consideration of propagation properties of waves as well as the excited state lifetimes. In case of known propagation properties of waves the excited state lifetime can be determined from the frequency‐dependent decrease of the wave amplitude. The proposed technique represents a new independent method for the determination of excited state lifetimes. This paper deals with first studies on excited state lifetime based on the frequency response of the amplitude of free streaming electron waves in He‐dc‐discharges.The results demonstrate the correctness of the idea about the decrease of wave signal in consequence of excited state lifetime.
Emissionspectroscopic Investigation of Bci3 Discharges
Authors: Breitbarth F.‐W. , Ducke E. 
Published: July 2007

AbstractRadiofrequency discharges in neat BCI3 exhibit 3 broad molecular emissions with intensity maxima at about 305, 350, and 480 nm. The 350 nm system consists of a progression of bands with an average separation of about 130 cm−1. All three emissions have an identical excitation kinetics in pulse discharges and are, therefore, believed to originate from the same emitter. Arguments are given that the emitter might be electronically excited BCl2.The dominant process of BCl(A) formation in neat BCl3 at low r.f. power is shown to be direct electron impact excitation of BCl(X). A transient excess population of BCl(A1II) in BCl3/Ar discharges is explained as due to an energy transfer from argon metastables.
Emissionspectroscopic Investigations On SiCl4 and Ccl4Si Plasmas for Etching Processes
Authors: Tiller H.‐J. , Sameith S. 
Published: July 2007

AbstractThe emission spectra of SiCl4‐ and CCl4/Si radio frequency discharges are analyzed. The broad emission between 310 and 360 nm is attributed to SiCl2 (Ã1B1 ‐ X1A1‐transition). The vibrational frequencies in the 1B1 state (ṽ2′) and in the 1A1 state (ṽ2″) and the energy difference between the vibrational ground states of the electronic 1B1 and 1A1 states are estimated.Further emission analysis results in an assignment of the 400 nm system to SiCl3 or SiCl3+ resp. Experimental results of the SiCl (B2Σ− – XΠr) and SiCl (B2δ – X2Πr) emission with high resolution are given.
Energetic Characteristics of Oxygen Plasma
Authors: Arutunyan G. G. , Babalyants L. P. 
Published: July 2007

AbstractA low‐temperature oxygen plasma is studied using the thermocouple, probe and spectral method in the range of 2–8 Torr pressure, 30–100 mA discharge currents, 0, 5, 10 m/s pumping velocity. The gas temperature, concentrations of electrons and oxygen atoms in the 3p5P state, and the longitudinal electric field are measured. Radial distributions of gas temperature and electron concentration are obtained. Ranges of pressures and currents are found in which considerable increases in electric field, discharge voltage, temperatures of gas and electrons are observed at pumping switched on. An estimate of the rate constant of the steplike ionization through the O2(a1Δg) state is given. The concentration of atomic oxygen in the ground state and excitation constant of the triplet O(3p5P) by electron impact are obtained from the solution of the balance equations and our experimental data.
Ordinary‐wave Propagation in Mirror‐Confined Plasmas
Authors: Saxena A. C. , Gupta G. P. , Rohatgi V. K. 
Published: July 2007

AbstractThe non‐relativistic dispersion relation for ordinary‐waves propagating in a hot plasma confined by magnetic mirrors is derived under small gyroradius approximation. The hot electron velocity distribution is modelled by a bi‐Maxwellian with a cutoff at the loss‐cone boundary. The dispersion relation is analyzed from propagation point of view. It is seen that the presence of loss cones in the electron velocity distribution reduces the high temperature effects in the ordinary‐wave propagation characteristics.