bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mikrowellendiagnostik der Rauschtemperatur im Stickstoffplasma der Schwachstromsäule
Authors: Bartels W. , Gundermann S. , Pauli W. , Winkler R. 
Published: July 2007

AbstractDiese Arbeit behandelt die Berechnung und Messung der Rauschtemperatur für ein stationäres und axial homogenes Säulenplasma einer Stickstoff‐Entladung. Die Berechnungen basieren auf einer Energieverteilungsfunktion der Elektronen, welche durch Lösung der Boltzmann‐Gleichung für ein Stickstoffplasma erhalten wurde. Die Rauschtemperatur in der Schwachstromsäule dieses Plasmas wurde mit einem Dicke‐Radiometer gemessen. Der Vergleich der berechneten und gemessenen Werte der Rauschtemperatur zeigt eine gute Übereinstimmung im betrachteten Parameter‐bereich. Zusätzlich wurde die Rauschtemperatur theoretisch näherungsweise unter Verwendung einer über die Energiebilanz der Elektronen angepaßten Maxwell‐Verteilung bestimmt und der kinetisch begründeten Rauschtemperatur gegenübergestellt.
Methods of Wall Charge Determination in External Electrode Gas Discharges. I. Experimental Arrangement
Authors: Kindel E. , Arndt R. 
Published: July 2007

AbstractFor direct and absolute determination of wall charges an electrostatic probe method, the field mill and the Faraday cup technique are used. The first scans the charge density distribution, while the two latter methods measure total charge magnitudes. Indirect methods, estimating the wall charges by integration of discharge current pulses are also used in the arrangement. The discharges are generated in a cylindrical quartz insulated Ne + N2‐filled discharge gap by individual voltage pulses having small risetimes and long duration.Preliminary tests, comparison of the methods and first results concerning charge density distributions will be given in part II of this paper.
Motion of Electrons and Ions in a Weakly Ionized Gas in a Field. 1. Foundations of the Integral Theory
Authors: Braglia G. L. 
Published: July 2007

AbstractA detailed analysis of an integral transport theory of electrons and ions in a gas in a field is presented. Different procedures allowing, in principle, the rigorous calculation of velocity distribution, drift velocity and diffusion coefficients are discussed. A derivation of a general expression for the transition probability, from a given velocity to another, which holds for any kind of collision, is given. Some questions linked to the convergence of iterative procedures of solution of some basic integral equations are also treated.
Lokale Messung von Driftgeschwindigkeit und Temperatur der Ionen einer Argon‐Niederdruckentladung mit resonanter Laserstreuung
Authors: Bergmann J. , Schubert M. 
Published: July 2007

AbstractThe radial ion drift velocity and temperature in an argon low‐pressure discharge have been measured by a resonant laser scattering method with high spatial resolution. The detection limit for the drift velocities was 2 · 104 cm · s−1. In the vicinity of the discharge axis the drift velocity grows linear with the distance from the axis. The measurements have shown the existence of a radial dependence of the ion temperature T1(r). Comparisons of axial ion temperature T⟂ with T‖(r = 0) are an experimental demonstration of the anisotropy of the ion velocity distribution in this kind of discharges.
Field Free Relaxation of the Electron Component in the Temporally Decaying Molecular Gas Plasmas Hydrogen and Nitrogen
Authors: Winklek R. , Wilhelm J. 
Published: July 2007

AbstractThis paper deals with the temporal relaxation of the electron component of weakly ionized, anisothermal and collision dominated plasma in the molecular gases hydrogen and nitrogen after jump‐like switching off of the electric field starting from stationary states. The investigation is based upon a solution of the non‐stationary Boltzmann equation using a finite difference approach of the resulting partial differential equation. Besides the temporal development of the energy distribution and of some macroscopic quantities of the electrons especially the characteristic relaxation times and their physical nature are discussed and compared with former results on the relaxation in an inert gas plasma.
Über den Gleichspannungsdurchschlag im Ultrahochvakuum
Authors: Jüttner B. , Siemroth P. 
Published: July 2007

AbstractMit hoher Zeitauflösung wurden Gleichspannungsdurchschläge mit bogenformierten Elektroden in einem dampffreien Vakuum untersucht. Die Durchschläge begannen stets mit einer Katodenfackel, deren Zündspannung stark mit der im Vordurchschlagsgebiet fließenden Feldemission korreliert war. Die zeitliche Entwicklung des Plasmas im Elektrodenzwischenraum, des Entladungsstromes und der Entladungsspannung während der Durchschläge konnten durch die Modelle der Explosivemission und des raumladungsbegrenzten Diodenstromes zufriedenstellend erklärt werden. Mit Elektrodenabständen bis 6 mm und Spannungen bis 120 kV konnte kein Mechanismuswechsel gefunden werden. Im allgemeinen wurde der Widerstand des Entladungskanals klein genug, um das Bogenstadium einzuleiten. Jedoch wurde auch in einigen Fällen eine Selbstbegrenzung der Entladung gefunden, die auf unzureichende Materialnachlieferung von der Katode zurückzuführen ist. Bei größeren Elektrodenabständen hatten die umgebenden Wände einen ausgeprägten Einfluß auf die Zündung der Entladungen.
The Rates of Formation of Negative Ions for Some Halocarbons in Nitrogen and in Argon‐Nitrogen Mixtures in Dependence on the Mean Electron Energy
Authors: Popp P. , Leonhardt J. 
Published: July 2007

AbstractAn experimental electron swarm method with a special electron capture detector arrangement (ECD) is described which allows one to modify the energy of low energetic electrons from thermal to 2.8 eV by means of radio‐frequency voltage. Using theoretically calculated values of electron energy distribution functions in nitrogen and argon the attachment coefficients and the formation rates of negative ions for chlorobenzene, benzyl chloride, chloroform, methylene chloride, nitrobenzene, propyl iodide, trichloroethylene and carbon disulfide were determined in dependence on the mean electron energy. Mean electron attachment cross sections could be estimated.
Zersetzung von CCl4 im HF‐Niederdruckplasma für plasmachemisches Ätzen von Aluminium
Authors: Tiller H.‐J. , Mohr R. , Berg D. , Breitbarth F.‐W. , Dumke K. , Göbel R. 
Published: July 2007

AbstractAfter a brief summary of decomposition processes occuring in a plasma etching reactor investigations of CCl4‐decomposition by gaschromatography and time resolved emission spectroscopy are described. The decomposition takes place in a plasma tube with external r.f. electrodes. The qualitative identification of decomposition products of CCl4 shows few main products only quite in contrast to plasma decomposition of hydrocarbons. These are CCl4, Cl2, C2Cl4, C2Cl6 and glow polymers. The dependence of the product distribution on power density and flow rate gives some hints for a rapid decomposition mechanism. The time resolved emission spectroscopy bases on a two channel method using a reference signal of an Ar line to eliminate the changing plasma conditions during the decomposition process. The limits of application of this method are discussed. Investigations of CCl‐, Cl2‐ and Cl‐intensity‐time‐functions also reveal the existence of a the rapid decomposition mechanism for which a dissociative electron attachment is supported giving rate constants in the expected order of magnitude.
Nonlinear Excitation of Plasma Convection
Authors: Spatschek K. H. , Laedke E. W. , Shukla P. K. , Yu M. Y. 
Published: July 2007

AbstractParametric excitations of electrostatic convective cells by drift waves as well as magnetostatic cells by Alfvén waves are considered. The growth rates are calculated for various limits of interest to plasma diffusion studies; our results agree with computer simulations. The problem of crossfield diffusion is also discussed. Finally, the coupling of magnetostatic modes with electrostatic modes is investigated and a variational principle for coalescence of magnetic islands is formulated.
Zur Mikrowellendiagnostik der Rauschtemperatur und der Trägerdichte eines Neonplasmas im Übergangsbereich zwischen der Freifall‐ und diffusionsbestimmten Säule
Authors: Gundermann S. , Bartels W. 
Published: July 2007

AbstractIn dieser Arbeit wird die experimentelle Bestimmung der Rauschtemperatur und der Elektronendichte behandelt. Die Plasmaparameter wurden mit Hilfe der Mikrowellen‐Resonatormethode im Druckbereich zwischen Diffusions‐ und Freifallbedingungen bestimmt. Die Berechnungen der Rauschtemperatur und der Elektronendichte erfolgten überwiegend mit den aus der Boltzmann‐Gleichung für Elektronen erhaltenen Energieverteilungsfunktionen. Es treten größere Abweichungen zwischen den gemessenen und berechneten Werten auf, wenn die mittlere freie Weglänge der Elektronen mit den Abmessungen des Entladungsrohres vergleichbar wird. Diese Unterschiede können durch eine erhöhte Wechselwirkung zwischen den Randschichtschwingungen und dem Plasma hervorgerufen werden.
Entladungsphänomene in meterlangen Luftfunkenstrecken bei positiver Schaltimpulsspannung
Authors: Engelmann E. 
Published: July 2007

AbstractDie Beherrschung höchster Spannungen in Luftisolierungen erfordert neben der Kenntnis der dominierenden Entladungsformen grundlegende Aussagen zu den Zünd‐ und Durchschlagprozessen. In meterlangen Kugel‐Platte‐Funkenstrecken wurden bei Variation der Elektrodenmakro‐ und ‐mikrogeometrie die Zündbedingungen und die räumlich‐zeitliche Entwicklung der Streamerentladung bei positiver Schaltimpulsspannung untersucht. Besonderes Interesse galt dabei dem Übergang der Streamerentladung in die Leaderentladung sowie der Stochastik der Entladungsprozesse. Aus den Untersuchungen wurden technisch‐physikalische Modelle zum Entladungsverhalten großflächiger Elektroden im Megavoltbereich abgeleitet, auf denen Kriterien für die Bemessung von Elektroden für Hochspannungsprüfanlagen aufbauen.
Properties of the Collision Operators of the Electron Boltzmann Equation for a Weakly Ionized Plasma. II. Compactness Proof and Statements on the Spectrum
Authors: Bartolomäus G. , Wilhelm J. 
Published: July 2007

AbstractThe compactness has been proved of the inscattering operator covering elastic, exciting and deexciting processes between electrons and heavy neutral particles. Starting point is the proof of the boundedness of the different inscattering operators for the individual collision processes using certain assumptions on the structure of the corresponding differential cross sections. Then, under somewhat more confined conditions the proff of compactness could be performed with the aid of the square integrability of an eightfold iterated kernel. On the basis of this property it was possible to draw conclusions with regard to the spectrum of the total collision operator. They are related to the continuous as well as the discrete part of the spectrum and are discussed in detail. For elastic collisions additional statements can be deduced from our investigation.
Remarks on the Energy Balance of Low Pressure Discharges
Authors: Valentini H.‐B. 
Published: July 2007

AbstractIncluding excitation and de‐excitation processes, direct and stepwise processes of the ionization, the particle balance and the energy balance of a positive column are jointly studied. It is shown that even near the axis the energy flux due to the radial electron drift can be only neglected provided that the mean electron energy is considerably less than the ionization energy. In some cases, it appears easier to apply the total energy balance instead of the energy balance of the electron gas alone.
Probe Measurements in a Beam Plasma Discharge
Authors: Babarickij A. I. , Klagge S. , Maass M. 
Published: July 2007

AbstractThe influence of the beam energy and beam current density on the parameters of the plasma is investigated. The efficiency of carrier generation by collective interactions (Langmuir‐oscillations) is compared with that by the single collision mechanism. The additional negative charging of the static probe caused by the beam electrons is used for the determination of the beam electron density.
Collisional Effects on the TM Modes in Parallel Plane Wave Guide Filled with Plasma
Authors: Arora B. B. , Phalswal D. R. , Varma N. L. 
Published: July 2007

AbstractThe reflection coefficient (CR) and the transmission coefficient (CT) of the TM modes in a half space (z < 0) parallel plane wave guide filled with homogeneous, collisional and moving plasma are derived and discussed. It is observed that CR and CT are modified depending upon the collision frequency of the electrons as well as that of the ions. There is a remarkable change in CR due to ion‐neutral collisions when the plasma moves against the direction of the TM modes.
Remarks on the Calculation of Eigenvalues and Generalized Eigenfunctions Using a Finite Dimensional Approximation for the Inscattering Part of the Boltzmann Collision Operator
Authors: Bartolomäus G. , Wilhelm J. 
Published: July 2007

AbstractFrom several points of view it is of advantage to know the properties of the collision operators in kinetic equations, e.g. in the well known Boltzmann equation, in particular for the purpose of solving eigenvalue problems. With regard to elastic, exciting and deexciting processes some attemps were recently made to investigate such operators in the Boltzmann equation describing the behaviour of electrons in weakly ionized plasmas.In the following we will prove that in the case of a finite dimensional inscattering operator the eigenvalues and the corresponding eigenfunctions can be represented explicitly. Finite dimensional operators were used successfully in special models to approximate the inscattering operators; they possess the property of compactness and are well suitable for analytical or numerical calculations.The representation has been obtained by solving an adequate linear equation system. The generalized eigenfunctions correspond to the normal solutions used by Case in the neutron transport theory. The regularization of the singular integrals which are necessary to obtain this solution will be given in detail. Further a velocity dependence of the collision frequency which need not be monotonous in the considered case and the dependence on the direction could be included.
Abweichungen von der Gleichgewichtsbesetzung der Ar‐II‐Terme in einem an der Oberfläche von Ferrelektrika erzeugten Plasma
Authors: Kusz J. , Musielok J. , Wanik B. 
Published: July 2007

AbstractA plasma obtained in argon near the surface of ferroelectric BaTiO3 ceramics has been examined in this work. It was found that the population densities of the excited Ar II doublet levels are greater than those of the excited Ar II quartet levels. This fact is related to the specific conditions of argon atoms excitation in the electric field of the ferroelectric domains. There is a possibility of ionization with simultaneous excitation of the neutral argon atoms.
Electron Kinetic Investigations of the Glow Discharge Plasma in ArHg Mixtures
Authors: Winkler R. B. , Wilhelm J. , Winkler R. 
Published: July 2007

AbstractIn the theoretical description of mixture plasmas used in fluorescent lamps a Maxwellian energy distribution and a two‐electron‐group model has been applied to determine the transport quantities and the main collision rates of the electrons. For various parameters, especially for a wide range of the ionization degree we calculated the electron energy distribution function for the ArHg plasma from the Boltzmann equation taking into account all important elementary processes and the Coulomb interaction. Further, we made a self‐consistent determination of the ionization degree additionally applying the current balance. In this way the energy distribution function and resulting transport coefficients, collision and energy transfer rates of the electrons were calculated and a comparison with the above models was performed. An interesting finding was that they satisfactorily describe the low energy part of the energy distribution, whilst in the tail of the distribution there is a gradually underpopulation as compared to the models. Furthermore, calculated and experimental results are compared.
Device for Producing and Investigating an Electron Beam Plasma Discharge
Authors: Schmidt M. , Föste T. , Michel P. , Šapkin V. V. 
Published: July 2007

AbstractA survey on the properties and applications of the beam plasma discharge is given. A device for the experimental investigation of this discharge is described in which a magnetically guided (H = 0.05−0.1 T), ribbonlike electron beam (eU = 0.5–5 KeV, I = 10−3−1 A) passes through a working chamber (p = 0.1–10 Pa; l = 10 cm, ø = 22 cm). The beam plasma discharge is sustained by collective beam plasma interaction. First results concerning the wall current and the ignition of the discharge as dependent on beam parameters are presented.
Energetische Eigenschaften eines 100‐kW‐Kaskaden‐Plasmatrons
Authors: Scheibe H.‐J. , Musikowski H. D. 
Published: July 2007

AbstractEnergetical properties of two different cascaded 100 kW‐H2‐plasma jets are treated. The losses of the heat are tested in dependence of the current. The influence of the geometrical place on the losses of heat in the plasma jet is shown. Questions of the adaption of the plasma jet to the power supply are discussed.
Electromotive Force and Dissipation in the Plasma‐Induced Arc
Authors: Ecker G. , Riemann K.‐U. , Wieckert Ch. 
Published: July 2007

AbstractA joint treatment of cathode spot, main plasma and anode sheath of the plasma induced are is given which shows an additional electromotive force in the plasma and accounts for the upper limit of the electron temperature. The plasma‐emf may be substantially larger than that of the sheath. The reduction effect of the dissipation is comparatively small. As a result existence limitations for the electron temperature and the neutral density are given which are quite different from those derived simply from the floating potential.
Surface Wave Generation in a Solid State Plasma by Relativistic Electron Beams
Authors: Grishin V. K. , Kanevskii M. F. 
Published: July 2007

AbstractThe linear and nonlinear theory of the surface wave generation in solid‐state plasma by a relativistic electron beam propagating in a gaseous plasma is treated. The proposed scheme is in better agreement with the conditions of real experiment. Besides, the neutralization of beam charge is possible and the oscillation frequency and its stability increase, etc. A nonlinear analysis permits to obtain the estimation of efficiency of the beam interaction with the surface wave and a number of other characteristics of the system.
Plasma‐Beam Discharge with a Pipe‐like Electron Beam as the Generator of Large Flows of Active Radicals
Authors: Atamanov V. M. , Levadny G. B. , Ivanov A. A. , Nasedkin Y. F. , Sereda Y. V. , Serov A. A. , Timchenko N. N. 
Published: July 2007

AbstractInvestigations on the device with a tube‐like electron beam have been carried out. The behaviour of the plasma‐beam discharge in active molecular gases at low pressures and at the pressure P = 1 Torr has been studied. The etching of crystalline silicon by active fluorine radicals has been carried out.
Non‐Maxwellian Electron Velocity Distribution Resulting from Electron‐SF6 Attachment Collisions
Authors: Schmidt R. , Stiller W. 
Published: July 2007

AbstractA model reaction system is considered consisting of a heat bath of argon atoms (c) and small concentrations of SF6‐molecules (m) and electrons (e) (number densities: ne ≪ nm ≪ nc). Within the model the time behaviour of the electron velocity distribution function is studied under the influence of elastic electron‐argon collisions and electron SF6 attachment collisions. On the basis of the distribution function time‐dependent macroscopic quantities (kinetic electron temperature. nonequilibrium rate constant of the attachment reaction) are calculated.
The Stability of the Relativistic Alfvén Waves
Authors: Ciubotariu C. D. , Zoler D. I. , Thirer N. S. 
Published: July 2007

AbstractWithin the framework of the special relativity, the system of reference comoving with Alfvén wave is defined and the form of the perturbations with respect to this system are deduced. The system of equations corresponding to the interaction of the waves, in the case when the relativistic Alfvén wave can generate new Alfvén waves and magnetosonic waves, is obtained in the most general form.In the one‐dimensional case the time dependent perturbation method is used for obtain the dispersion equation for the relativistic coupled waves (decay processes). Finally, by solving numerically the dimensionless dispersion equation, the instability domains of the Alfvén waves are obtained. It is shown that there are possible decay processes and modulational instabilities.
Untersuchungen des turbulenten Strömungsfeldes eines schnellen eingeschlossenen Plasmastrahls
Authors: Hayess E. 
Published: July 2007

AbstractEs werden radiale Temperatur‐ und Geschwindigkeitsverteilungen an einen eingeschlossenen turbulenten Plasmastrahl mit Thermoelement‐ und Drucksonden gemessen. Durch iterative Korrekturberechnungen werden neben den Temperatur‐ und Geschwindigkeitsfeldern auch die Felder verschiedener thermodynamischer Funktionen bestimmt. Das Verhalten des Plasmastrahls unterscheidet sich grundsätzlich nicht von den der Gasstrahlen und Flammen.Infolge der Masseneintragung aus der Umgebung divergiert der Strahl und klingt sehr schnell ab.Die aus Gründen der Massenerhaltung an der Behälterwand entlang verlaufende Rückströmung wird abgeschätzt. Sie ist so klein, daß sie mit den benutzten Meßmitteln nicht mehr nachgewiesen werden kann.
Zut Kinetik der plasmachemischen Methan‐Umsetzung in einer stillen elektrischen Entladung
Authors: Rutkowsky J. , Drost H. , Mach R. 
Published: July 2007

AbstractIn einer durch eine 50 Hz, 10 bzw. 20 kV‐Wechselspannung betriebenen stillen elektrischen Entladung vom Barrieren‐Typ wurde bei Drücken von 3,32–9,96 × 104 Pa Methan plasmachemisch in einfache Kohlenwasserstoffe umgesetzt. Als gasförmige Hauptprodukte wurden Äthan und Propan identifiziert, wogegen Buten, Azetylen, Äthylen und Propylen in deutlich niedrigeren Konzentrationen auftraten. Der Methan‐Zerfall in Abhängigkeit von der Entladungszeit entspricht bis zu 1000 s streng einer Exponentialfunktion. Die Bildung der Alkane, insbesondere des Äthans, verläuft nach dem Schema einer Folgereaktion; sie läßt sich kinetisch gut durch eine Geschwindigkeitsgleichung 1. Ordnung beschreiben.
On the Question of Increasing Maxwellization of the Electron Energy Distribution Function due to Electron — Electron Interaction with Growing Ionization Degree in the Beam Discharge Plasma
Authors: Winkler R. , Wilhelm J. 
Published: July 2007

AbstractThe question of the establishment of an almost complete Maxwellian energy distribution of the electrons in a given discharge plasma is of importance, especially under the aspect of a more convenient determination of transport and rate coefficients.In [5] an energy space averaged criterion for the establishment of such a structure of the electron energy distribution function in the stationary beam discharge plasma of molecular gases was formulated from a heuristic point of view.This paper investigates this question in detail starting from the adequate Boltzmann equation of such plasmas. Energy resolved conditions for the establishment of an almost complete Maxwellian distribution are derived from the kinetic equation. Using one of these conditions, the formal derivation of the mentioned averaged condition is performed and its limitations are shown. The fulfilment of the energy resolved and of the averaged conditions are illustrated and discussed using solutions of the kinetic equation in purely molecular hydrogen for two parameter sets yielding larger and smaller deviations of the real distribution function from the Maxwellian form.