bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nonlinear Theory of the Instability of a Modulated Electron Beam of Low Density in a Plasma. II. Energetic Analysis of Certain Types of Monoenergetic Beam‐Plasma Interactions Based on the Čerenkov Resonance Condition
Authors: Kruscha K. J. G. , Kondratenko A. N. 
Published: July 2007

AbstractThe energy and momentum balance equations for a potential wave in a monoenergetic electron beam‐plasma system are considered in the linear approximation, when the wave is in Čerenkov resonance with the beam particles. An energetic analysis of certain types of beam‐plasma instabilities is given. It is shown that the energy and momentum balance equations are consistent with the dispersion relation for all unstable waves. From this fact follows that the energy and momentum densities of all linear unstable waves in reactive beam‐plasma systems are equal to zero. An interpretation and a possible classification of beam‐plasma instabilities are given.
Temperature Effects on the Beat Heating of a Collisional Magnetoplasma
Authors: Arora B. B. , Phalswal D. R. , Varma N. L. 
Published: July 2007

AbstractThe beat heating of a magneto‐plasma by two antiparallel electromagnetic waves at different temperatures is examined. The effects of plasma temperature, plasma electron collisions, plasma ion collisions and magnitude and direction of the magnetic field on the excitation of plasma electron waves and plasma ion waves are studied. A formula for the power absorption density of the plasma by using Maxwell's equations in conjuction with continuity and momentum equation. including collisions and pressure tensor terms, is derived. The contribution of the plasma temperature to the power absorption density, both at low and high beat frequencies, of the collisional and the non‐collisional magnetised plasmas is found very significant and is illustrated numerically. The inclusion of pressure tensor term in the momentum equation is also found to cause characteristic changes in the power absorption density of the plasma with the orientation of magnetic field.
Formation of Discharges between Glass Insulated Electrodes in Ne + 1% N2 Mixtures. II. Frequency Dependence and Discharge Modes
Authors: Lange H. , Stern W. 
Published: July 2007

AbstractDischarges between glazed electrodes for p = 2.67 kPa Ne + 1% N2 and pd = 1.3 kPa cm (p = gas pressure, d = electrode distance) are investigated. They are sustained by a sine wave voltage of variable frequency f. Measurements of the space time structure of the radiation emission provide information of the build up and quenching of discharges and of the structure of the fully developed ac‐discharge.It is shown that the discharge types for the different values of frequency and amplitude of the sine wave sustaining voltage are dynamically developed Townsend and glow discharges. For f ≦ 4 kHz the optical structure and its temporal behaviour largely depends on the increment of the sustaining voltage. For f ≧ 20 kHz the axial structure of radiation emission is modified by the influence of consecutive discharges due to residual ions (f ≌ 20 kHz) and metastable Ne(3P2)‐atoms (f > 20 kHz) existing for several periods of sine wave. The Penning effect of metastable Ne‐atoms with N2 molecules then produces start electrons for each discharge in a sequence which improve the initial conditions for the breakdown. Relations between space time structure and breakdown voltage as a function of frequency f are discussed.
On the Anomaly of the Electrical Field Strength in the Magnetized Positive Column of Glow Discharges at Small Currents
Authors: Deutsch H. , Klagge S. 
Published: July 2007

AbstractThe axial electrical field strength in the positive column of glow discharges at small currents in noble gases passes through a maximum with the increase of an axially directed magnetic field. This maximum is explained of the contrary processes of extension of the radial profiles of the electron energy and the concentration of the metastable atoms on the one hand and the decrease of the ambipolar diffusion losses on the other hand. Using the results of measurements of metastable atom concentrations, the electrical field strength is calculated as a function of magnetical induction with the aid of a set of balance equations. The radial and axial distribution of the electrons is checked by probe measurements. The methods for measuring the concentration of the excited atoms and the electrons are described.
Coronal and Collisional — Radiative Model of the Plasma for the Case of Hydrogen Glow Discharge
Authors: Ferdinand J. , Vlček J. , Čejková E. 
Published: July 2007

AbstractIn this paper the comparison of coronal and collisional‐radiative models of the plasma of the positive column of hydrogen glow discharge is made. From the good agreement between theoretical and experimental results it follows that both models are suitable for description of the two spectral lines intensities ratio dependence on electron temperature.
General Form for the Electron Distribution Function for an Inhomogeneous Fully Ionized and Magnetized Plasma Interacting with an Alternating Electric Field
Authors: Burdujan I. , Zoler D. 
Published: July 2007

AbstractIt is the purpose of this paper to give a general form for the isotropic and vectorial part of the distribution function for electrons, in a fully ionized and magnetized plasma, interacting with an alternating electric field.By making the assumption, that the ions have an equilibrium distribution, we obtain the needed solutions as series with respect to time and complex exponentials. Also have indicated a new manner in which the solution may be obtained with any precission we want. A general form for density current is obtained. It should be denoted that these results are obtained, without being done any previous assumption on the temporal dependence of the distribution function.
The Knudsen Ion Layer Problem in the Theory of the Collisionless Sheath
Authors: Chekmarev I. B. , Sklyaroba E. M. , Kolesnikova E. N. 
Published: July 2007

AbstractThe interaction of a partially ionized continuum gas with a negatively charged electrode is investigated theoretically. It is supposed that ld ≪ 1, where ld is the Debye length, l is the mean‐free‐path. The self‐consistent solution is given for two cases: lI ≫ l and lI ∼ l, lI is the effective ionisation length. The matched asymptotic expansions method is used. The Bohm sheath criterion is shown to be satisfied automatically in the considered cases.
Application of the Inverse Matrix Pearce Method to Plasma Spectroscopy
Authors: Sato M. 
Published: July 2007

AbstractThe inverse matrix method is a variation of the Pearce method for numerically solving the Abel integral equation in plasma spectroscopy. Differed from the original method, the matrix method allows a direct determination of radial intensity profiles without iterative calculation from the zone of the plasma edge. From the tests through numerical simulations, it is found that this method has the higher accuracy than the original method by reducing the errors caused by iterative calculations. Since no smoothing procedure is included, the matrix method is vulnerable to receive the effects of random scattering. However, when appropriate smoothing is made, this method becomes as useful as the other methods. The Nestor‐Olsen and Barr methods are also tested for comparison.
Electrodynamic Model of Initiation and Extinction of Emitting Sites Interacting Together in Cold Cathode Spots (Type A) in Air
Authors: Liegmann K. 
Published: July 2007

AbstractFrom an electrodynamic and simple quantum‐mechanical point of view a model is proposed which explains the phenomena of minimum arc current as well as the formation and extinction of tiny emitting sites interacting together in cold cathode spots (called type A) on the base of a specific coupling between the tunnelling “average” electrons and the metal bulk phonon field. The model seems to be especially applicable to such experimental conditions where typical trumpetlike microcraters with pronounced rims with diameters in the range 0.5—1 μm are left by microspot ensembles on the cathode surface.The model yields emitting‐site lifetimes, currents, current densities and radii in the order of τps ⋍ \documentclass{article}\pagestyle{empty}\begin{document}$ \sqrt {3M/m} $\end{document} τ0 ⋍ 10−11 sec, Imin = 4π ℏ \documentclass{article}\pagestyle{empty}\begin{document}$ \sqrt {n/\mu _0 m} $\end{document}⋍ 0.4 A, j = nevs ⋍ 4 · 1013 A/m2 and ra ⋍ 2c/ωPl ⋍ 30 nm (τps…lifetime of short wave phonons, M … atom mass, m … electron mass, τ0 … mean free collision time of Fermi electrons at room temperature, n … conduction electron density in the metal bulk, vs … metal bulk sound velocity, c … light velocity, ωPl … metal bulk plasma frequency (values for copper). The lifetime and the interaction diameter of an emitting site (event) ensemble are derived to τpl ⋍(M/m) τp ⋍ 3 nsec and Λpl = νsτpl ⋍ 10 μ (τpΛpl … lifetime and mean free path of long wave phonons).
Generalized Boundary Conditions in an Existence and Uniqueness Proof for the Solution of the Non‐Stationary Electron Boltzmann Equation by Means of Operator‐Semigroups
Authors: Bartolomäus G. , Wilhelm J. 
Published: July 2007

AbstractRecently, based on the semigroup approach a new proof was presented of the existence of a unique solution of the non‐stationary Boltzmann equation for the electron component of a collision dominated plasma. The proof underlies some restrictions which should be overcome to extend the validity range to other problems of physical interest. One of the restrictions is the boundary condition applied. The choice of the boundary condition is essential for the proof because it determines the range of definition of the infinitesimal generator and thus the operator semigroup itself. The paper proves the existence of a unique solution for generalized boundary conditions, this solution takes non‐negative values, which is necessary for a distribution function from the physical point of view.
Excitation of Plasma Waves by Means of a Weakly Ionized Monoenergetic Particle Beam
Authors: Kondratenko A. N. , Kruscha J. , Kuklin V. M. , Tkachenko V. I. , Vorobjov V. M. 
Published: July 2007

AbstractThe instability of a weakly ionized monoenergetic particle beam in a plasma is investigated by means of the weak cold beam description. Such an instability is characterized not only by a collective interaction of the beam electrons with the plasma electrons via the unstable waves but also by collisions of the beam electrons with the neutral beam particles.The considered instability is characterized by a strong velocity focusing and intensive bunching of the beam electrons. An essential enlargement of the maximum wave amplitude relative to the resonant reactive instability [1] was observed.
The Measurement of Current Column Plasma Parameters in the Glow Discharge at Increased Pressure
Authors: Akishev Yu. S. , Napartovich A. P. , Pashkin S. V. , Trushkin N. I. 
Published: July 2007

AbstractResults of the probe and thermocouple measurements of the constricted stationary glow dis charge in nitrogen and air at pressures up to 60 Torr are given. It was shown that the main energy processes in the column are the heating of the gas and its vibrational excitation. The balance of charged particles is determined by the electron‐ion recombination and the stepwise ionization through metastable levels of nitrogen molecules. The results obtained can be used in the numerical simulation of a moving filament during the current constriction in the glow discharge.
Das Abklingen des Plasmas der Impulslaser‐Gasentladung in Stickstoff
Authors: Wojaczek K. 
Published: July 2007

AbstractFor a typical laser gas discharge, the concentration and temperature of the most important plasma components at the end of the current pulse are calculated on the basis of given data for the tube radius, gas pressure, and energy input. Relating to a postdischarge time up to 1 s, the deionization, the association of the nitrogen atoms, the deexcitation of metastable molecules and the relaxation of the vibration temperature are investigated by means of simple balance equations. Finally the influence of plasma relicts on the following discharge pulse is discussed.
On the Theory of Ion‐Cyclotron Instabilities in Collisional Rotating Plasma
Authors: Kurko O. V. , Mikhailovskii A. B. 
Published: July 2007

AbstractThe role of collisions in the ion‐cyclotron instabilities in the rotating plasma has been investigated. Collisional varieties of such instabilities at moderate collisions have been shown possible. At frequent enough collisions the total stabilization of such instabilities takes place. A survey of the contemporary state of the problem of the ion‐cyclotron instabilities in rotating plasma has been given.
Der zeitliche Verlauf einer Elektronenstrahl‐gesteuerten Hochdruckentladung in CO2‐Lasergasgemischen
Authors: Albrecht H. , Gündel H. , Seliger K. 
Published: July 2007

AbstractThe energy which may be introduced into the plasma of an e‐beam sustained laser discharge depends on the electron loss processes as recombination and attachment. Measuring the time behaviour of the discharge current both the recombination and the attachment rate coefficients can be determined.The results of such investigations reported here suggest that some widely used assumptions have to be proofed carefully once more. It could be shown that in the case of pure nitrogen the recombination coefficient decreases very rapidly immediately after the discharge ignition even if the reduced electric field strength remains unchanged. In CO2‐discharges such a behaviour could not be observed. Moreover, it has been found that CO2‐discharges are stable only as long as they are recombination determined.These results are supported by additional investigations in N2—CO2‐mixtures. Some conclusions according to the operation of tunable high pressure lasers are given.
Complex Calculations of High‐Pressure Discharge Irradiation Characteristics
Authors: Sinyarev G. B. , Gradov V. M. 
Published: July 2007

AbstractA wide range of problems related to the determination of the high‐pressure irradiation parameters in inert gases and vapors of metals is considered. A new method for calculating equilibrium states of the computed thermodynamic systems is described and its applications to the determination of the plasma composition are disclosed.The method for computing basic discharge characteristics including the determination of material functions of the plasma producing media along with the optical absorption factors' a temperature field in a discharge stabilized by a quartz shell with regard to irradiation energy transfer carried out by bright‐line and continous spectra, spectral distributions for the radiant fluxes and discharge irradiation efficiency is presented.Results of multiple calculations to obtain said characteristics in krypton, xenon, vapors of sodium, potassium, rubidium and their mixtures with inert gases are given. Calculated data is a satisfactory agreement with the results of experiments published by various authors.
Plasma Oscillations and Their Influence on Certain Properties of Nonideal Plasma
Authors: Kurilenkov Yu. K. , Valuev A. A. 
Published: July 2007

AbstractThe hypothesis is proposed that Langmuir plasma oscillations can exist in nonideal plasma inspite of great collisional frequency. This possibility is confirmed by numerical estimations and the results of several experiments. The influence of plasma oscillations on electron states density and conductivity of nonideal plasma is considered. The simple formula obtained for conductivity agrees well with available experimental data.
On the Nonlinear Theory of Surface Wave Excitation in a Collisional Solid State Plasma
Authors: Grishin V. K. , Kanevskii M. F. , Ivanov S. T. 
Published: July 2007

AbstractThe nonlinear equations governing relativistic electron beam‐surface wave dynamics in dissipative P‐S‐plasma are derived. The influence of P‐plasma on time saturation, amplitude of the wave at saturation and damping factor is analyzed. The obtained results are discussed from the physical point of view.
Propagation and Diagnostic of Ion Acoustic Waves in a Low Pressure Argon Discharge
Authors: Sato M. , Wagatsuma Y. , Sato T. 
Published: July 2007

AbstractIn a dc argon discharge column of pressure 5 × 10−4 torr, ion acoustic waves are studied experimentally. Plasma parameters obtained from the phase velocity of waves are compared with the Langmuir probe measurements. The wave diagnostic method yields the electron temperature lower than the probe method by a factor of 3…︁5, if the atomic argon ion is assumed as a dominant ion species. The axial profiles of ion drift velocity show the presence of ions flowing toward the anode along the potential drop in flont of it. Also it is found that the surface condition of the cathode sensitively affects the propagation of ion acoustic waves through the changes in discharge parameters.
Studies on the Decomposition of Carbon Dioxide in a Low‐Temperature Plasma
Authors: Szymański A. , Huczko A. 
Published: July 2007

AbstractThe decomposition of carbon dioxide was studied in an argon plasma jet, generated by a direct‐current arc discharge. The decomposition degree of carbon dioxide was up to 0,4 at an effective energy consumption lower than 1 MJ/mole CO. The efficiency of high‐temperature decomposition of carbon dioxide to carbon monoxide and oxygen is essentially dependent both on the quenching intensity of the products, which prevents from the reverse oxidation reaction in the system, as well as on the proper conditions of plasma‐substrate mixing.
Zur plasmachemischen Umsetzung von GaAs mit CCl4 und CF2Cl2 in Gegenwart von Sauerstoff
Authors: Prösch U. , Buttke K. 
Published: July 2007

AbstractEs wurde der plasmachemische Abtrag von GaAs durch CCl4 und CF2Cl2 bei unterschiedlichen Leistungen eines 27,3 MHz Generators und unter Zusatz von Sauerstoff gemessen. Zur Interpretation der erhaltenen Ergebnisse wird ein einfaches kinetisches Modell vorgeschlagen.
Inclusion of the Full Electromagnetic Interaction in Correlations and Physical Quantities
Authors: Lambert A. J. D. , Schram P. P. J. M. 
Published: July 2007

AbstractDensity‐density correlations in a homogeneous, isotropic, classical plasma are calculated with inclusion of the full electromagnetic interaction. This leads to isotropic homogeneous field limits, contrary to the electrostatic approximation, that is consequently not valid for small wavenumbers. Application of the theory of generalized functions, combined with Kramer Kronig relations makes it possible to deal with the integrals that occur in the transverse part, provided a nonrelativistic approximation has been applied. As a side result Kubo's formula, applied to the electric conductivity, and generally derived under restriction to the electrostatic approximation, reappears for the case that the full electromagnetic interaction is included.
Resonant Wave‐Particle Interaction in an Explosively Unstable Beam‐Plasma System II. Investigation of the Relaxation Behaviour of the Electron Beam
Authors: Kruscha K. J. G. , Leven R. W. 
Published: July 2007

AbstractThree typical saturation mechanisms of the explosive instability (EI) in a beam‐plasma system are investigated. It is shown that the maximum values of the electric field strengths of the explosively unstable plasma waves can be of the same order as the maximum wave amplitude of the linearly unstable waves. Some conclusions with regard to the role played by the EI in the evolution of a real beam‐plasma system are presented. The relaxation of a strongly modulated electron beam by the explosive wave coupling mechanism is examined in an appendix. A qualitative interpretation of the diversity of the EI saturation mechanisms found in this investigation is given.
Nonlinear Interaction of S‐Polarized Incident Radiation and Surface Waves in Magnetoactive Plasma
Authors: El‐Seragy N. M. , Khalil Sh. M. , Sayed Y. A. , El‐Sherif R. N. 
Published: July 2007

AbstractThe effect of an external magnetic field on the nonlinear interaction of S‐polarized electromagnetic radiation incident on a S‐polarized surface wave in a plasma layer was studied analytically. We have calculated the amplitudes of generated waves at combination frequencies. The generated waves are of P‐polarization and can be either electromagnetic or surface waves, depending on the signal of the value=\documentclass{article}\pagestyle{empty}\begin{document}$ ^{\chi '^2 = \frac{{k'^2 }}{{\varepsilon '}} - \frac{{\omega '^2 }}{{c^2 }} + k'\frac{\partial }{{\partial x}}\frac{{\varepsilon '_2 }}{{\varepsilon '\varepsilon '_1 }}} $\end{document}.
Electronic Heat Conductivity of a Partially Ionized Hydrogen Plasma
Authors: Schlanges M. , Kremp D. , Kraeft W. D. 
Published: July 2007

AbstractThe electronic contribution of the translational heat conductivity of a partially ionized hydrogen plasma is determined, starting from a quantum kinetic equation, which takes into account the two particle scattering between the free charge carriers as well as electron‐atom collisions. Plasma effects are included by statically screened potentials. In connection with a mass action law, the influence of the different collision terms on the electron heat conductivity is shown. An estimation is given for the contribution of the atoms. The pressure ionization (Mott effect) is described by a minimum behaviour of the heat conductivity.
Distribution of Excited Atoms and Ions in a Plasma Generated at the Surface of Ferroelectric Ceramic
Authors: Janus H. , Kusz J. , Musielok J. 
Published: July 2007

AbstractThe distribution of excited atoms and ions in a plasma generated at the surface of ferroelectric ceramic has been studied. For all studied spectral lines of He I, Ar I, Ar II and hydrogen a decrease of the total line intensity with the increasing distance from the ceramic surface has been found. The shapes of these distributions are characteristic of the specific spectral lines. The distributions for He I lines depend strong on the concentration of argon in the helium — argon mixture. The effect of overpopulation of some excited Ar II ion levels in an argon discharge observed already in a previous work has been found also in the case of a helium — argon plasma.
The Theory of Ionization Waves in the Contracted Discharge of Noble Gases
Authors: Golubovski Ju. B. , Nekuchajev V. O. 
Published: July 2007

AbstractPositive column plasma in noble gases at middle pressures is analysed for stability in the frames of the linear hydrodynamic theory. At critical values of pressure and current the discharge becomes unstable to radial contraction (contraction) and to wave disturbances of the type of current pinch constrictions (contraction ionization waves). Ionization waves in the contracted discharge are three‐dimensional formations with electron concentration oscillations on the axis in the opposite phase with current pinch cross section. The discharge diffuse‐recombination theory was used for analysing the problem of instability arising.