bluuebunny/crossref_metadata_2025_split huggingface dataset:
Zur mikrophysikalischen Beschreibung des schwachionisierten Stickstoffmolekülplasmas der positiven Säule von Glimmentladungen. III. Elektronenkinetische Kenngrößen unter Berücksichtigung der Dissoziation durch direkten Elektronenstoß
Authors: Pfau S. , Winkler R. 
Published: July 2007

AbstractDie Ergebnisse einer Berechnung der makroskopischen Kenngrößen der Elektronen für das schwachionisierte Stickstoffmolekülplasma im reduzierten Feldstärkebereich von 1 V/(cm Torr) bis 100 V/(cm Torr) aus der homogenen stationären Boltzmanngleichung unter Berücksichtigung der direkten Dissoziation durch Elektronenstoß werden mitgeteilt. In Fortführung der vorangegangenen Untersuchungen [1, 2] konnte ein auch die direkte Dissoziation der N2‐Moleküle berücksichtigender Satz von Wirkungsquerschnitten aller wesentlichen Elektronen‐Molekülstoßprozesse festgelegt werden, welcher eine gute Beschreibung der Geschwindigkeitsverteilung und einiger experimentell bestimmter makroskopischer Größen der Elektronen erlaubt.
Trivelpiece‐Gould‐Modes in an Axial Inhomogeneous Plasma
Authors: Prinzler H. , Heymann P. 
Published: July 2007

AbstractExperiments on the propagation of TG‐modes in a weakly inhomogeneous plasma are reported. The modes travel from the high density part (ω < ωpe) to that of lower density (ω > ωpe). The wavelength decreases as expected but an increase of the longitudinal fieldstrength predicted by collisionless theory could not be observed. Two nonlinear effects appear one after another with increasing wave amplitude. These are the sideband instability and a decay into the drift frequency range occuring in the whole plasma column. Neither the region ω ≈ ωpe nor the very vicinity of the exciter antenna are distinguished. The second instability is accompanied by effective electron heating.
[Russian Text Ignored]
Authors: [Russian Text Ignored]  
Published: July 2007

AbstractThe stability of the electromagnetic plasma confinement by powerful external s‐polarized pump waves is considered. The parametric excitation of standing electromagnetic waves along the plasma boundary with frequencies close to the frequency of the pump wave leads to a periodic density modulation of the plasma boundary. The density disturbances along the direction of the external wave field are connected to the excitation of transverse p‐polarized surface waves while the modulation in the direction perpendicular to the pump field are created by the parametric interaction between the external wave and s‐polarized trapped leaking oscillations. Only when the leaking waves are excited the scale length of the modulation is larger than half the free space wave length of the incident radiation.
Die Relaxation der Geschwindigkeitsverteilungsfunktion der Elektronen im homogenen Feld mit elastischen und anregenden Stößen. III. Die Einstellung des periodischen Verhaltens der Elektronen‐komponente im elektrischen Feld großen Modulationsgrades
Authors: Wilhelm J. , Winkler R. 
Published: July 2007

AbstractIn Fortführung der kinetischen Untersuchungen zum periodischen Verhalten der Elektronen‐komponente eines schwachionisierten Ne‐Plasmas einer Glimmentladung im periodischen elektrischen Feld [4] großen Modulationsgrades wird im folgenden Beitrag das Einstellverhalten der Isotropverteilungsfunktion der Elektronen und der hieraus folgenden wichtigsten makroskopischen Kenngrößen in den periodischen Zustand numerisch berechnet und physikalisch interpretiert. Auf der Basis der nichtstationären Boltzmanngleichung wird einerseits das Einstellverhalten bei unterschiedlichen Gleichfeldanteilen und annähernd konstantem Modulationsgrad verfolgt. Durch ent‐sprechende Variation der Periodendauer des elektrischen Feldes und ausgehend von verschiedenen stationären Anfangszuständen wird es möglich, den Einstellvorgang und die ihn charakterisierende normierte Einstellzeit ausgehend von der Grenze eines praktisch momentanen Einstellverhaltens bis hin zur Einstellung in der Nähe der durch sehr kleine Modulationsgrade der Isotropverteilung charakterisierten Hochfrequenzgrenze zu analysieren. Andererseits wird der Einfluß einer Änderung des Modulationsgrades auf den Einstellprozeß und auf die normierte Einstellzeit untersucht und physikalisch gedeutet. Dabei erweist sich das Spektrum der allen Momentanwerten des periodischen elektrischen Feldes zugeordneten Einstellzeiten stationärer Zustände [2] auch hier als grundlegend für die physikalische Interpretation des Einstellvorganges in periodische Zustände. Insgesamt ergeben sich größenordnungsmäßige Änderungen der Einstellzeit des periodischen Zustandes bei entsprechender Variation der Parameter des elektrischen Feldes.
The Theory of the Low‐Pressure, High‐Current Discharge Column: The Influence of the Degree of Ionization and of the Neutral Gas Temperature on the Radial Profiles of the Charged Particle Density, the Neutral Gas Density, and on the Electron Temperature
Authors: Valentini H.‐B. 
Published: July 2007

AbstractTo give a theoretical description of the low‐pressure positive column at high degrees of ionization under ambipolar and under free‐fall conditions, the differential equations for the first two and the first three moments of the velocity distribution functions of the atoms, the ions, and the electrons are derived. In particular, to close the set of the equations in a physically reasonable manner, typical features of the discharge in the free‐fall regime are taken into consideration by the statements for the heat flux tensors of the ion gas and of the neutral gas. Numerical solutions are given for the radial profiles of the number density, of the radial drift velocities, and of the radial and the azimuthal temperatures in the ion gas and in the neutral gas. The charged particle density profile is broadened under diffusion conditions, if the electron temperature and the degree of ionization increase. In the free‐fall regime the charged particle density profile depends only weakly on the electron temperature and is slightly constricted if the degree of ionization increases. The degree of ionization affects the density profiles of the charged particles and the neutral gas under ambipolar diffusion conditions more than under free‐fall conditions. Rising neutral gas temperature leads to a weak narrowing of the charged particle density in both regions. The electron temperature depends only weakly on the forms of the density profiles of the charged particles and of the neutral gas. Furthermore, the ion flux density to the wall and the wall potential are calculated in dependence on the degree of ionization and on the neutral gas temperature.
Untersuchungen zum Einfluß der Plasmaparameter auf die Löslichkeit von Glimmpolymerschichten aus Hexamethyldisiloxan (HMDS)
Authors: Schmidt M. , Maass M. , Möller W. 
Published: July 2007

AbstractDurch Sondenmessungen an einer durchströmten Argon‐HMDS‐Glimmentladung bestimmte Werte für den axialen Potentialgradienten, die Temperatur und die Dichte der Elektronen erlauben eine Diskussion von Ursachen der Löslichkeitsänderung der unter diesen Bedingungen abgeschiedenen Glimmpolymerschichten. Es wird ein Modell vorgeschlagen, wonach das Absinken der Löslichkeit auf eine Mehrfachradikalbildung im Volumen zurückgeführt wird. Betrachtungen zum Energieumsatz bei der Schichtbildung werden durchgeführt.
Dispersion Theory of Self Excited Ion Acoustic Waves in a Hot Cylindrical Plasma. I. The General Formula
Authors: Goepp X. , Leven R. 
Published: July 2007

AbstractStarting from the system of the Vlasov‐Poisson equations, a closed equation for the potential of the electrostatic field of ion acoustic waves in a hot cylindrical plasma with drifting electrons is found. For the electrons ideal reflection at the plasma boundary is supposed. From this equation in a first approximation a dispersion relation is derived, which includes dispersion equations presented in the literature for special cases.
Wave Propagation in Waveguide Filled with Hot Collisional Plasma
Authors: Phalswal D. R. , Varma N. L. 
Published: July 2007

AbstractFor a cylindrical waveguide filled with hot, collisional and homogeneous plasma, the dispersion relation is derived and discussed for particular cases of interest. It is observed that the collision frequency (v) and thermal velocity (v0) have a significant effect in damping of low frequencies waves at the wall of the wageguide.
Die Eigenschaften stationärer Hochstrom‐Niederdruckentladungen in Edelgas‐Ionen‐Lasern
Authors: Ebert W. 
Published: July 2007

AbstractDischarges at high current densities and low pressures in the transition region from free fall to ambipolar diffusion conditions are the laser media of noble gas ion lasers. A short review of well known discharge theories of low pressure discharges is given.Experimental results of discharge parameters and plasma data obtained for different ion laser tubes are described. Wall probes were used to measure the electron temperature, the current density of the positive ions at the wall, and the mean electron density. Optical methods provided measurements of axial ion temperature, axial temperature of the neutral gas, and the mean drift velocity of the positive ions.For electron temperatures higher than 4 eV, the energy ballance, the electrical field intensity, the axial drift velocity of the ions and the electrons, the mean neutral gas density and the degree of ionization are in agreement with the results from the free fall theory.
Unified System of Differential Equations for Plasmas and Boundary Layers
Authors: Valentini H.‐B. 
Published: July 2007

AbstractStarting from the Boltzmann equation the moment equations up to the third order for a non‐quasineutral plasma are derived. It is shown that for a non‐quasineutral plasma, in the distinction from the second order set of moment equations, the systems of the first order and of the third order can be closed in a physically reasonable manner by a relatively simple method when near the walls the ion gas has a high drift velocity caused by an electric field. From this follows that in non‐quasineutral plasmas the ion pressure must be neglected in the first order set of equations consisting of the equations of continuity and of momentum transfer. Terms of the first order in the ion pressure related to the electron pressure are taken into consideration for the third order system. In this way one obtains a unified set of differential equations to treat both the quasineutral plasma core and the space charge sheath at the walls jointly taking into account a non‐vanishing ion temperature. This set of equations is applied to the positive column in the free‐fall regime.
On Nonlinear Resonant Absorption of Surface Waves
Authors: Gradov O. M. , Stenflo L. , Tegeback R. , Sünder D. 
Published: July 2007

AbstractWe consider the resonant absorption of surface waves in a cold electron plasma by taking into account the nonlinear change in the electron density profile which is caused by the wave pressure in the transition layer. Equations, which describe the time evolution of the amplitudes of the electric fields of the surface waves, are obtained and solved. It is shown that the time‐behaviour of the surface waves can be significantly different from that obtained from linear theory, and nonlinear effects can thus change the rate of absorption of the surface wave energy and can also stabilize linear surface wave instabilities.
Drifting Electron Effects on Strongly Non‐Linear Ion‐Acoustic Solitons
Authors: Leven R. , Steinmann W. 
Published: July 2007

AbstractThe influence of drifting electrons on the properties of ion acoustic solitons is discussed. The range of Mach numbers within which solitary waves are possible and the dependence of soliton velocity on amplitude are given. It is shown that solitary waves exist for Mach numbers M < 1 in the presence of drifting electrons.
Nonideal Plasma Generation by Mechanical Compression
Authors: Buschig D. , Clemens G. , Finn T. , Hess H. , Metzke E. , Wirsig M. 
Published: July 2007

AbstractNonideal plasmas have been generated by mechanical compression with a so‐called ballistic compressor. The Debye numbers reached were 0.4 in argon and 0.2 in xenon. The experimentally determined pressure, specific volume, and temperature are compared with calculations of the compression using different models of the charged particle interaction. This comparison shows that heat losses may take an essential part in the interpretation of the experimental results.
Modifications of the Surface of a Stainless Steel Limiter During Operation in the T‐10 Tokamak
Authors: Hildebrandt D. , Laux M. , Lingertat J. , Pech P. , Reiner H.‐D. , Strusny H. , Wolff H. 
Published: July 2007

AbstractParts of a stainless steel limiter used in the T‐10 tokamak for about 1000 discharges have been analyzed by several standard analysis techniques as SEM, EDS, SAM, AES, RBS and SIMS with respect to modifications of surface structure and chemical composition. Erosion phenomena due to melting and evaporation, arcing, and sputtering could be observed on limiter parts exposed to the plasma flux. In these regions the chemical composition was changed only slightly, whereas in regions shielded by other internal structures of T‐10 impurity layers with a thickness up to about 3000 Å were deposited.Additionally on the limiter surface there has been found a considerable number of microscopic particles. They seem to originate from different internal components of T‐10, as the fixed W/Mo‐limiter, a Ti‐anode, and Inconel made parts of the vessel.
Verallgemeinerung der Methode der singulären Normallösungen für isotherme irreversible Vlasov‐Systeme
Authors: Vojta G. , Mocker M. 
Published: July 2007

AbstractIrreversible Vlasov‐Systeme, d. h. Systeme, die durch eine kinetische Gleichung vom Vlasov‐Typ mit zusätzlichen entropieproduzierenden Stoßtermen zu beschreiben sind, werden mit der Technik der singulären Normalmoden und singulären Integralgleichungen untersucht. Dazu wird eine neue indirekte Methode entwickelt, die eine einfache Verallgemeinerung des ursprünglich für stoßfreie Vlasov‐Plasmen entwickelten Formalismus von Case gestattet, im Gegensatz zu einer komplizierteren Methode, die von den Autoren für eine erstmalige Anwendung des Formalismus der singulären Normalmoden auf irreversible Vlasov‐Systeme angegeben wurde (1970). Der linearisierte Vlasov‐Operator, der durch vollständige Bhatnagar‐Gross‐Krook‐Stoßintegrale als die wichtigsten Modellstoßterme vervollständigt ist, wird für ein nichtrelativistisches, nichtentartetes, stationäres Elektronengas mit neutralisierenden positiven Ionen und neutralen Teilchen ohne Magnetfeld und bei konstanter Temperatur im Detail untersucht, Verallgemeinerungen auf kompliziertere irreversible Vlasov‐Systeme sind möglich. Der wesentliche Punkt der entwickelten indirekten Methode ist die Einführung einer transformierten Elektronen‐Verteilungsfunktion, die als additives Glied ein Integral über die gewöhnliche Verteilungsfunktion enthält. Die neue kinetische Gleichung und ihre adjungierte Gleichung werden wieder lineare Integralgleichungen und liefern einen Satz von regulären und singulären Normalmoden, für die der Beweis der Orthogonalität und der Vollständigkeit angegeben wird. Das Anfangswertproblem wird exakt gelöst. Ein Vergleich der Ergebnisse mit denen der Laplace‐Transformationstheorie nach Landau, die für die volle Vlasov‐BGK‐Gleichung formuliert wird, ergibt Übereinstimmung der Lösungen. Das Zeitverhalten der Lösungen wird diskutiert.
Methods of Wall Charge Determination in External Electrode Gas Discharges. II. Preliminary Tests, Comparison of Methods, Distributions
Authors: Kindel E. , Arndt R. 
Published: July 2007

AbstractFirst experiments with the arrangement described in part I of this paper resulted in three spurious effects: shifting of characteristic values due to ageing effects, dissymmetric behaviour of wall charges and currents with respect to the voltage pulse sign, and backfiring. The comparison between the direct and the indirect methods demonstrated the sensitivity of the indirect ones to uncertainties and variations in effective cell capacities. The wall charge density distributions are axially symmetric and can be described in the electrode range by ƒ (x) = ae.
Teilprozesse bei der Ozonerzeugung mittels stiller elektrischer Entladungen. Teil II: Die Ozon‐ und Stickoxydbildung im Ozonisator
Authors: Hirth M. 
Published: July 2007

AbstractDie Arbeit untersucht die Ozonerzeugung und den Einfluß von Stickoxyden bei der Betreibung eines Siemens‐Ozonisators mit Luft als Arbeitsgas. Sie zeigt im einzelnen die Anwendung der bekannten Ozon‐Reaktionsgleichungen bei einer stillen el. Entladung, die Ortsabhängigkeit der Ozonkonzentration und Stickoxydkonzentration im Ozonisator, die Ozon‐Gleichgewichtskonzentration als Funktion der Temperatur und das Zusammenspiel zwischen Ozon und Stickoxyden im Ozonisator.
Spectral Investigation of an a. c. Plasma Display
Authors: Musa G. , Nâastase L. , Trache M. 
Published: July 2007

AbstractThe work presents the spectral investigations on an a.c. plasma display, in order of a better understanding of the physical phenomena taking place in such a device. The spectral characteristics of the panel filled with a Penning mixture Ne + 0.1% Ar are presented and the influence of the nitrogen addition on these characteristics was evidentiated. The presence of the trace of nitrogen in the device may be used in order to evidentiated. The presence of the trace of nitrogen in the device may be used in order to evidentiate small leaks or imperfections in pumping and outgasing processing of the display.
Macroscopic Equations for a Multicomponent Plasma
Authors: Hebenstreit H. 
Published: July 2007

AbstractFrom the balance equations for partial quantities we derive equations for lumped quantities, e.g. a generalized Ohm's law. They are especially useful for a three‐component system (electrons, one species of ions and neutral particles). Certain conditions are derived and investigated to describe a plasma with more than three components by the lumped quantities.
Spektrallinienprofile des neutralen Argons im nahen infraroten Spektralbereich
Authors: Musielok J. 
Published: July 2007

AbstractIn dieser Arbeit wurden Untersuchungen der Linienprofile von ArI im nahen infraroten Bereich durchgeführt. Die Strahlung der Plasmasäule wurde auf Photoplatten mit Hilfe des Plangitterspektrographen PGS2 registriert. Für ausgewählte Linien wurde die spektrale Intensitätsverteilung gemessen. Aus der gemessenen Halbwertsbreite und dem Emissionskoeffizienten der Hβ‐Linie wurden die Elektronenkonzentration und die Temperatur bestimmt. Mit diesen Plasmaparametern wurden die theoretischen Profile der ausgewählten Linien berechnet und mit den experimentellen Ergebnissen verglichen. Es wurde eine gute Übereinstimmung zwischen Experiment und Theorie festgestellt.
Cathode Phenomena with Arcs and Breakdowns in Vacuum
Authors: Jüttner B. 
Published: July 2007

AbstractA short review is given on cathode phenomena in vacuum. Based on experimental results about temporal and spatial development of craters, arc spots and breakdown flares, conclusions are drawn with respect to the dynamics of crater heating, the connection of craters with spots, the current density, the reason of arc spot movement, the nature of different spot types, and the analogy of cathode flares with arc cathode spots. Referring only to surface processes, some general results could be obtained which allow a unified description of various cathode phenomena.
On the Motion of Unipolar Arcs in a Tokamak
Authors: Hintze W. , Laux M. 
Published: July 2007

AbstractTracks of unipolar arcs found on parts of the T‐10 tokamak (shield and pipe section of the surface analysis station WASA, edge of the movable limiter) are analyzed.It is the aim of this paper to explain the observed deviations of the arc motion from the first order retrograde direction. It is shown that the drift of the arc which occurs if the magnetic field is inclined to the cathode surface, and which was studied in detail by Robson [1], causes the deviations. To this end, arc tracks on three differently shaped electrodes (cone, cylinder, sphere) are calculated theoretically and compared with the data from T‐10. Good agreement is obtained if the drift angle is approximately equal to one half of the inclination angle of the magnetic field. The present investigation is consistent with the model of retrograde arc motion of Robson and von Engel [2, 3].
[Russian Text Ignored.]
Authors: [Russian Text Ignored.] B. , [Russian Text Ignored.] M. H. 
Published: July 2007

AbstractAn investigation of the heterogeneous low temperature plasma ionization is stimulated by practical needs. Earlier theoretical studies of the ionization process are connected with many difficulties and realized by simple models.In this paper a solution of the kinetic equations of the electron‐ion process and the Poisson equation for a self‐consistent electrostatic potential is presented.A pecularity of the volume density determination of the electron‐ion atmosphere around a solid particle, the connection between the integral and local density of charged particles and the own particle volume are taken into consideration.The influence of characteristic parameters of the condensed phase on the equilibrium electron density is received.
Stability of a Stratified Partially Ionized Plasma in a Horizontal Magnetic Field
Authors: Sankhla V. D. , Bhatia P. K. 
Published: July 2007

AbstractThe dynamic instability of a composite hydromagnetic compressible plasma has been studied to include the effects of finite electrical conductivity. Making use of existence of the variational principle which is shown to characterize the problem, proper solutions have been obtained for a semi‐infinite composite plasma having density stratification along the vertical. It is found that the frictional effects with neutrals have a stabilizing influence on the growth rate of the unstable disturbances while compressibility as well as magnetic resistivity both have a destabilizing influence.
A Model for Diffuse Breakdown in High Pressure Gases at Homogeneous Electric Field Strengs
Authors: Gündel H. 
Published: July 2007

AbstractA model of the breakdown in high pressure gases is presented taking into consideration the finite voltage rise time at the discharge electrodes and a finite initial charge carrier density in the gap. Several types of breakdown could be distinguished important for several applications. Thus, the range of existence of high pressure laser discharges at a given preionization density and circuit parameters can be calculated. Moreover, the change in the breakdown characteristics of high pressure gases at high temperatures is explained. This behaviour seems to be important for understanding the physical processes in circuit breaker chambers.
Modulational Instability of Two Longitudinal Waves in a Hot Electron Plasma
Authors: Das K. P. , Sihi S. 
Published: July 2007

AbstractBy Whitham's method of averaged Lagrangian two coupled nonlinear Schrödinger equations are derived that give the evolution of the amplitudes of two longitudinal waves, both propagating in the same direction in a hot electron plasma. It is found that a single wave is modulationally stable, while two waves together are modulationally unstable if either the difference between the group velocities of the two waves is sufficiently large, or if this difference is sufficiently small and a coefficient, which couples the two waves, is sufficiently large.
Bestimmung der Ionendichte in strömenden Hochdruckplasmen mittels elektrischer Staupunktsonden
Authors: Lachmann J. , Winkelmann G. 
Published: July 2007

AbstractEs wurde eine elektrische Staupunktsonde zur Messung lokaler Ionendichten in strömenden Hochdruckplasmen (p = 105 Pa) entwickelt. Die experimentellen Ergebnisse der im Raumladungs‐Konvektions‐Gebiet arbeitenden Sonde bestätigen die Richtigkeit der Sondentheorie bezüglich der Kennlinienform und der gemessenen Ionendichte, die mit spektroskopischen Werten verglichen wird. Die Abweichung zwischen beiden Meßverfahren ist geringer als eine halbe Größenordnung.