bluuebunny/crossref_metadata_2025_split huggingface dataset:
Zur Glimmentladungspolymerisation des Benzols‐Vergleich gemessener mit berechneten Wachstumsraten polymerer Filme aus der Ne‐Benzol‐Entladung
Authors: Deutsch H. , Klagge S. 
Published: July 2007

AbstractThe growth rate of thin polymer films polymerized in the positive column of a dc‐glow discharge on the conditions [total pressure: Pneon + Pbenzene = 1 Torr, admixture of benzene : 10−4 < x < 10−1, discharge current: 1 mA — 15 mA] is calculated and measured. The calculation is based upon a previously developed polymerization model [6], which ascribe the major part of the growth rate to the insertion and crosslink of benzene ions into the substrate surface. The calculated growth rates of the polymer films and the separated portions of the considered polymerization processes correspond to the experiments within the bounds of the actual possibilities of analyzing the model.
The Theory of the Low Pressure Discharge in the Strong Ionization Regime
Authors: Valentini H.‐B. 
Published: July 2007

AbstractA system of integro‐differential equations describing the velocity distribution functions of the neutral atoms and of the ions and the radial profiles of the electric potential and the particle densities in the positive column at low pressures and high degrees of ionization is derived. This system is solved for a simplified, but self‐consistent, plane model. Both the initial velocity of the ions and the neutral gas depletion caused by the ionization processes are taken into account. For a cylindrical model a solution is obtained for the region near the axis. With rising neutral gas temperature the radial ion flux density is slightly increasing. The pressure tensor, the heat flux tensor, and several components of the corresponding tensor of the fourth order for the ion gas are calculated. It is shown that on the axis the radial and the azimuthal ion temperatures are smaller than the neutral gas temperature because the ions generated out of neutral atoms are retarded during the flight to the axis.
On the Nature and the Motion of Arc Cathode Spots in UHV
Authors: Bushik A. I. , Jüttner B. , Pursch H. 
Published: July 2007

AbstractCathode spot types and spot motion of arcs in ultra high vacuum have been investigated with large area cathodes that consisted of two adjacent pieces of Mo and Cu. Arc currents were 20–60 A dc and 8–20 kA pulse (duration about 1 ms). Two spot types occured with different velocities and surface erosion: Type 1 spots are typical for surfaces covered by oxides or thick adsorption layers, whereas clean surfaces show only type 2 spots.During arc‐conditioning both types exist simultaneously in a complex mutual dependence. Type 1 spots react weakly on the cathode material, while type 2 spots burn preferentially on Cu and at the boundary line between Mo and Cu. The motion of type 1 spots is determined by the expanding spot plasma, whereas type 2 spots show a step‐by step motion, determined by explosions in the arc craters. Generally a spontaneous formation of type 2 spots beneath the arc plasma takes place only with contaminated surfaces (probably by a transition from type 1 to type 2 spots). Thus a breakdown between plasma and cathode surface requires the presence of contaminations. The observed effects occur in low current dc‐arcs as well as in high current pulse arcs. They are discussed for different spot models.
Experimental Measurements on the Current Balance at the Cathode of a Cylindrical Hollow Cathode Glow Discharge
Authors: Helm H. 
Published: July 2007

AbstractThe contribution of positive ions, photons and metastable particles to the secondary emission of electrons from the cathode of an argon glow discharge with cylindrical cathode is measured by sampling the plasma species through a small orifice in the cathode wall and analyzing them in a high vacuum region. Additional experiments are made with a second apparatus which enables the sampling fo plasma species from the negative glow and the dark space.The paper describes the experimental techniques used in both cases and presents estimates on the validity of the results obtained.The positive ions are found to be the dominant contribution to the discharge current at the cathode. The secondary emission of electrons is — in decreasing order of importance — due to impact fo singly charged ions, doubly charged ions and metastable atoms.
Messung relativer Radialprofile der Ionendichte in einer Argon‐Hochstrom‐Niederdruckentladung mittels resonanter Laserlichtstreuung
Authors: Schubert M. , Bergmann J. 
Published: July 2007

AbstractRadial ion density profiles have been measured in an argon high current low pressure discharge by a laser resonance scattering technique with a high spatial resolution in the range of 100 μm. For electron temperatures at 2 eV in segmented discharge channels a radial dependence of averaged electron impact excitation cross section seems to be probable. The influence of several kinetic effects of ions on the measurements has been discussed.
Diffusionstheoretische Beschreibung der Dissoziation und des Ionenhaushaltes im schwachionisierten Säulenplasma der Wasserstoffentladung. II. Makroskopische Kenngrößen der Elektronen im H/H2‐Mischplasma
Authors: Michel P. , Pfau S. , Rutscher A. , Winkler R. 
Published: July 2007

AbstractFür das stationäre und homogene H/H2‐Mischplasma werden die Ergebnisse der Berechnung des Isotropteils der Geschwindigkeitsverteilungsfunktion f(U), der Transportgrößen Ū, be, De. der Stoßfrequenzen für Dissoziation und Direktionisation sowie aller wesentlichen Energieverluste durch elastische und unelastische Stöße an die Komponenten des Mischplasmas mitgeteilt. Diese Berechnungen erfolgten mittels der Boltzmanngleichung der Elektronen in Abhängigkeit von der normierten elektrischen Feldstärke E/p0 und der Gemischzusammensetzung xD und wurden für E/p0‐Werte von 7,5–100 V/cm Torr und für beliebige Gemischzusammensetzung durchgeführt.
The Calculations of the Concentrations, of the Radial Distributions, and of the Radial Particle Currents of Excited and of Doubly Charged Ions in Low Pressure Discharges
Authors: Valentini H.‐B. 
Published: July 2007

AbstractA system of differential equations describing the radial profiles of the number densities and of the radial drift velocities of the ions and of the electrons in positive columns at low pressure containing several species of ions is derived. Excited ions and doubly charged ions, generated in two‐step processes by electron impacts, the inertia of the ions and space charge effects are taken into account. For the excited ions de‐excitation processes by electron collisions and by spontaneous emission are regarded. A set of nonlinear equations to determine the population densities and the initial values of the differential equations and corresponding boundary conditions are put up. Numerical solutions are given for discharges in argon under free‐fall conditions similiar to argon ion lasers. One notices that without stepwise processes via excited ion levels the concentration of double charged ions remains small. In some cases the radial drift of the ions considerably reduces the population of the metastable ion levels. The radial density profiles of the double charged ions and of long‐living excited ions considerably deviate from the squared radial profile of the electron density. In addition, for low degrees of ionization the theory of the free‐fall column given by Tonks and Langmuir is extended to plasmas containing two species of ions.
Reaktionskinetik der Ozonbildung in der Sauerstoffglimmentladung
Authors: Sabadil H. , Bachmann P. , Kastelewicz H. 
Published: July 2007

AbstractHg‐light absorption at λ = 2537 Ǎ by O3 has been used to measure the concentration of O3 in the positive column of an oxygen glow discharge under the nonstationary conditions of the Q‐form (tube diameter 3:4 cm). For all gas pressures investigated (p = 7 — 12 torr) the O3 density (n3) as a function of the current reaches a remarkable maximum at i ≈ 15 mA. n3 max was found to increase almost linearly with the gas pressure. At i = 80 mA, on the other hand, n3 increases according to a quadratic relation.In order to understand the dependence of n3 on the pressure and on the current density (or equivalently on the electron density ne) a kinetic model previously developed has been used involving the following particles
equation image
.For example, it can be shown that in the region of the maximum of n3 one main production process of ozone is the associative detachment reaction
equation image
.The calculated maximum of the ozone density is higher than the measured one and appears at higher electron density.
Teilprozesse bei der Ozonerzeugung mittels stiller elektrischer Entladungen. I. Die elektrische Entladung im Ozonisator
Authors: Hirth M. 
Published: July 2007

AbstractDie Arbeit befaßt sich mit den Eigenschaften der stillen el. Entladung in einem Siemens‐Ozonisator. Sie enthält im einzelnen Untersuchungen zur Ladungs‐ und Potentialverteilung auf dem Dielektrikum, zum zeitlichen Stromverlauf einzelner Teilentladungen. zur statistischen Ver‐ teilung der bei einer Einzelentladung geflossenen Ladungsmenge, zur räumlichen und zeitlichen Temperaturverteilung und zur Lage der Wärmequellen im Luftspalt.
Zur Mikrowellendiagnostik der Elektronendichte im Neonplasma der Freifallsäule
Authors: Gundermann S. , Bartels W. , Leven R. 
Published: July 2007

AbstractEs wird über die Elektronendichtemessung in der Freifallsäule einer Neonentladung berichtet. Die experimentelle Bestimmung erfolgte mit Hilfe der Resonanzfrequenzänderung eines Mikrowellenresonators. Die auf diesem Wege ermittelten Werte der Trägerdichte werden zur Berechnung der Existenzgrenze von Ionenschallwellen verwendet.
Der freibrennende Störlichtbogen
Authors: Klengel H. , Böhme H. 
Published: July 2007

AbstractLong high current arcs (I ⩽ 60 kA, f = 50 Hz, t ⩽ 200 ms, l = 1 m) appear after discharges at electric power systems. The arc must be localized in a separate volume in order to protect the equipment from the high temperature. The arc is stabilizing by the plasma‐beam starting at its bottom.The properties of the plasma‐beam are described: general phenomena, the length as a function of current and time, the behaviour in a half‐cycle and the acoustic emission. Several conclusions for the construction of the protective armatures are presented.
Spherical and Cylindrical Solitons in a Warm and Multi‐Electron Plasma
Authors: Kalita M. K. , Bujarbarua S. 
Published: July 2007

AbstractThe ion acoustic soliton has been investigated in spherical and cylindrical geometry in a warm plasma having two electron components each described by a Boltzmann distribution. It has been shown that both potential hump and potential dip are possible in this case.
Perturbational Approach to Force — Free Toroidal Equilibria
Authors: Cap F. , Zagrodzirński J. 
Published: July 2007

AbstractSolutions of the equation curl B = γB inside a torus‐shaped region with vanishing normal component on the torus surface are sought by the perturbation method. The perturbation parameter is proportional to the curvature of the torus, i.e zero‐order solutions are exact helical solutions for a straight tube.
Ionization Dynamics in a Pulse Disturbed Magnetically Confined Helium Plasma
Authors: Prinzler H. , Heymann P. 
Published: July 2007

AbstractThe equilibrium of a magnetized Helium plasma is disturbed by a pulsed Trivelpiece‐Gouldwave. The electrons obtain the energy by linear collisionless wave absorption. The relaxation phenomena of density and energy are explained in terms of two relaxation times τE, τ1 and a quantity giving the additional ionization. These quantities are derived from a small signal fluid model based upon energy and particle balance equations. In the experiment they are taken from the transient curves of Langmuir‐probe current, optical line radiation and the noise power at the electron cyclotron frequency.The experimental conditions are: Helium‐gas, p = 1 …︁ 5 Pa, Te = 4 eV, n = 1 …︁ 5 · 1010 cm−3, B = 6,5 · 10−2 T, 27 MHz rf plasma source, low frequency fluctuation level < 1%, classical losses. The energy relaxation time …︁E = 10 …︁ 15 μs is given by inelastic collision losses. The ionization time constant τ1 is related to the instantaneous ionization frequency during the transient state. It shows a high value at the very beginning of the pulse which must be explained by a tail formation in the distribution function and enhanced radial losses becoming Bohm‐like in the transition phase.
Mass Spectrometric Determination of Partial Ionization Cross Sections
Authors: Märk T. D. 
Published: July 2007

AbstractA review of the measurement of partial electron impact ionization cross sections for rare gas atoms and molecules is presented, with particular regard to the low electron energy regime (<200 eV). Recently developed experimental techniques are surveyed. Predictions of quantal and classical approximations as well as some empirical formulae are compared with the experimental data. In conclusion a set of recommended atomic ionization cross sections is given for electron energies ranging from threshold up to 14 keV. Finally, the existence and measured appearance potentials for the production of doubly ionized rare gas dimers are discussed.
Deposition and Etching of Thin Films by Means of Beam Plasma Discharge with Tube‐Like Electron Beam
Authors: Atamanov V. M. , Levadny G. B. , Ivanov A. A. , Klagge S. , Maass M. , Nasedkin Y. F. , Sereda U. V. , Serov A. A. , Timchenko N. N. 
Published: July 2007

AbstractThe efficiency of energy dissipation caused by the mechanism of turbulent plasma heating from a tube‐like electron beam in a electronegative gas is measured calorimetrically. Amorphous Si‐layers are deposited from a SiH4/Ar discharge both on conducting and nonconducting substrates and are analyzed by means of Auger‐spectrometry. The velocity and specific energy of etching of SiO2‐layers in a CF4‐plasma are determined.Measured etching velocities of tungsten surfaces biased differently against the space potential provide information on the mechanism of plasma etching in a SF6‐plasma. Simultaneously performed Langmuir‐probe measurements permit predictions to be made on the properties of the etching plasma.
An Improved Two‐Dimensional Snow‐Plow Model for Plasma Acceleration in Coaxial Geometry
Authors: Grosu I. 
Published: July 2007

AbstractThe plasma sheath acceleration in a system of two coaxial electrodes is studied by means of a two‐dimensional snow‐plow model presented in [9]. An improved expression for the variable plasma inductance is used. The calculated values for the final axial velocity and the current intensity are in favorable agreement with experimental values. A comparison between the results of these calculations and those of some recent analytical models is presented.
The Construction of Systems of Equations Describing Gas Discharges Containing Several Species of Atoms and Ions, Including Stepwise Processes, Negative Ions, and the Spatial Variation of the Temperatures
Authors: Valentini H.‐B. 
Published: July 2007

AbstractThe sets of differential equations usually used for the description of the low pressure discharges are underconstrained if several species of atoms and of ions and stepwise processes are taken into consideration. Using the equations of continuity, of momentum transfer, and of energy transfer for each species it is shown that, besides known closing statements for these sets of differential equations, additional conditions are necessary. It is found that the following relatively simple condition is sufficient for positive ions. The radial pressure gradient has to be assumed to vanish at least with the third order as the distance from the axis approaches zero. Various simpler and also more accurate and cumbersome approximations describing non‐excited atoms, positive and negative ions are investigated. Under some conditions one can formulate additional boundary conditions at the wall instead of additional conditions on the axis.
Ionenschallinstabilitäten in Edelgas‐Gleichstromentladungen bei niedrigen Drücken. II. Vergleich der experimentellen Ergebnisse mit einer eindimensionalen kinetischen Dispersionstheorie
Authors: Leven R. , König A. 
Published: July 2007

AbstractThe experimental measurements of the propagation properties of self‐exicted ion acoustic waves in a de‐low pressure column are compared with a one dimensional dispersion theory. The corresponding dispersion relation is developed starting from the linearised Vlasov equation with a Davydov‐type collision term. It is shown, that the mean features of the propagation behaviour of the ion acoustic waves can be explained by the theory. The experimental results concerning the dependence of the upper limit frequency of the waves upon the discharge current should be analysed on the base of new results from plasma diagnostics, taking also into account nonlinear and geometrical effects.
Nonlinear Theory of the Instability of a Modulated Electron Beam of Low Density in a Plasma. I. Conservation Laws of Energy and Momentum for Electromagnetic Waves in a Nonequilibrium Dispersive and Dissipative Medium in the Case of a Slow Change of Amplitude and Phase of the Wave
Authors: Kruscha K. J. G. , Kondratenko A. N. 
Published: July 2007

AbstractA formula is given for the energy and momentum conservation laws for a narrow spectrum of electromagnetic waves in an unstable dispersive and dissipative medium by any level of dissipation and on condition that the amplitude and phase change slowly in the time and space period of oscillations. It is shown that the density of energy and momentum of the motion of resonant particles, connected with the propagation of the electromagnetic wave, generally cannot be expressed by the dielectric function of the unstable system. For example it is demonstrated that the well known Landau formula for determining the density of the wave energy in a unstable monoenergetic beam‐plasma system in general is not applicable as it is often done in literature.
Experimentelle Untersuchungen axialer Druckgradienten in Niederdruck‐Hochstromentladungen
Authors: Ebert W. 
Published: July 2007

AbstractEs wurden Messungen des axialen Druckes in Niederdruck‐Hochstromentladungen durchgeführt. Es konnte gezeigt werden, daß der axiale Druck im Entladungsrohr hauptsächlich durch dir Größe des Kathodenraumes oder des Anodenraumes bestimmt wird und nicht durch Entladungsstrom und Fülldruck. Für den Fall, daß das Anodengefäß wesentlich größer als das Kathodengefäß ist, stellt sich ein nahezu konstanter Druck im Entladungsrohr ein (grad p ≈ 0). Die Ergebnisse dieser Experimente sind in Übereinstimmung mit numerischen Rechnungen.
IR‐Emissionsspektrum eines Argon‐Plasmastrahls zwischen 4 und 25 μm
Authors: Winkelmann G. , Tilgner J. 
Published: July 2007

AbstractDas infrarote Emissionsspektrum eines Argon‐Plasmastrahls (1 atm) wurde im Wellenlängenbereich von 4–25 μm (2500–400 cm−1) mittles eines Fourier‐Transform‐Spektrometers untersucht. Neben zahlreichen schmalen Emissionalinien des Argons (Halbwertsbreite ⩽ 1 cm−1) traten bei 4,636 μm, 7,435 μm und 12,346 μm sehr breite Intensitätsmaxima mit einer Halbwertsbreite von 7; 20 bzw. 39 cm−1 auf.
On Electron Concentration Distribution along the Radius of the Positive Column of a Glow Discharge in Electronegative Gases
Authors: Arutunyan G. G. , Galechyan G. A. , Tavakalyan L. B. 
Published: July 2007

AbstractIt is shown in this paper that the form of the electron concentration distribution along the radius of the positive column in an oxygen discharge depends on the relative concentration of negative ions α = n‐/ne in the plasma.It is found that in discharges in electronegative gases everywhere along the radius of the positive column, where α > 10, the electron concentration is equal to its value on the tube axis (plane electron distribution along the radius of the positive column).It is shown that an increase of the discharge current leads to the decrease of α and to the change of the distribution of profile ne from plane to parabolic. However, weak laminar oxygen pumping along the positive column leads to more plane an electron concentration distribution because an increase of the negative ions concentration takes place. It is induced by the decrease of oxygen atoms density on account of their carrying out by the flow.
Nonlinear Theory of the Instability of a Modulated Electron Beam of Low Density in a Plasma. III. Derivation of Nonlinear Equations for the Time‐ and Space‐Problems (Single Wave Model)
Authors: Kruscha K. J. G. , Kondratenko A. N. 
Published: July 2007

AbstractIn this paper it is shown that there are, in dependence on the properties of the system, several systems of nonlinear equations for the description of the nonlinear “hydrodynamical stage” of the beam‐plasma instability. It becomes evident that the well known system of equations for the resonant wave instability in beam‐plasma systems is not applicable for the case of strong dissipation of the wave energy in the plasma and for the case of the excitation of nonresonant waves. As well for the time‐problem as for the space‐problem there are derived three different systems of nonlinear equations. An energetic analysis of the nonlinear stage of the excitation of resonant waves is given. Anomalous growth of the amplitude of resonant waves by interaction with strong modulated electron beams is examined.
Bestimmung der Gastemperatur in Wasserstoffniederdruckentladungen
Authors: Krysmanski K. H. 
Published: July 2007

AbstractIn the positive column of hydrogen low pressure gas discharges the radial temperature profil was measured by an interferometric method. A Michelson‐interferometer in combination with an He—Ne‐laser was used. In the range from 532 to 1330 Pa and 25 to 100 mA for a water cooled tube of inner diameter of 20.5 mm axis temperatures from 340 to 500 K with a nearly parabolic profil were found. Rotational temperatures from the Fulcher‐bands were systematically lower about 15%.
Cathodic and Anodic Spot Phenomena on Rotating Electrode Disks and Plasmatron Electrodes
Authors: Kranz E. 
Published: July 2007

AbstractThe arc spot life time and velocity before reaching melting temperature have been calculated for different electrode materials. They vary between 10−10 to 10−14 s and 102 to 106 m/s for heat flux densities of 109 to 1012 W/m2. The experimental examination of such results was carried out by means of fast rotating electrode disks and tubular electrodes in plasmatrons. The measurements resulted in life times of more than 10−5 s with erosion rates from 10−10 to 10−2 g/As and electrode spot diameters ranging from 0,01 to 5 mm while the heat flux density varied between 107 to 1012 W/m2. Ten different types of continuous traces, single spots, and craters have been found. Some spot phenomena, the high erosion rates of rotating disks and the similarity of ignition events have been clarified for electrodes made from good conductive materials and less conductive. But the melting and boiling of the spot surfaces was inevitable in all cases.
Zur plasmachemischen Umsetzung von CO/H2‐Gemischen zu leichten Kohlenwasserstoffen in einer Glimmentladung
Authors: Mach R. , Drost H. , Dube G. , Spangenberg H.‐J. 
Published: July 2007

AbstractCO/H2‐Gemische lassen sich durch nichtthermische Aktivierung in einer Glimmentladung teilweise in Kohlenwasserstoffe (KW), insbesondere Methan, umsetzen. Als höchster Umsetzungsgrad des CO → KW ergab sich 12%, als höchster Methan‐Partialdruck 3%. Die CO‐Umsetzung ist abhängig von den Entladungsparametern, der Entladungszeit bzw. dem Energieeinsatz und dem CO/H2‐Mischungsverhältnis. Die gebildeten KW sind Zwischenverbindungen, die zu höheren, darunter auch festen KW, weiterreagieren. Auf Grund massenspektrometrischer Ionenanalysen wurde für die KW‐Bildung ein Reaktionsschema entwickelt, das sowohl für ionische als auch für Neutralteilchen‐Reaktionen als gültig angesehen wird.