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  • 1
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Contents Fusion machines with closed magnetic field configurations have emerged as the principal means of achieving magnetic confinement of plasmas. The necessary behaviour in the case of the W VII stellarator experiment at Garching, to be more precise, the transient coil currents occurring during a current pulse produced with a pulse power generator are analyzed. Allowance is thereby made for all inductive coupling, both in smooth operation and in the case of sudden coil shorting. The currents determined are then used to calculate the magnetic forced exerted on coils (Lorentz forces) as functions of time and shortcircuit impedance.
    Notes: Übersicht Für den magnetischen Einschluß eines Plasmas haben Fusionsmaschinen mit geschlossenen Magnetfeldkonfigurationen vorrangige Bedeutung gewonnen. Die dazu erforderlichen toroidalen Spulenanordnungen werden hinsichtlich ihres elektrischen Verhaltens am Beispiel des Garchinger Stellarator-Experimentes W VII untersucht. Genauer gesagt, werden die transienten Spulenströme während eines von einem Stoßleistungsgenerator gelieferten Stromimpulses analysiert. Dies geschieht unter Berücksichtigung aller induktiven Kopplungen sowohl für den ungestörten Betrieb wie für den Fall eines plötzlich eintretenden Spulenkurzschlusses. Die ermittelten Stromstärken dienen dann dazu, die auf die Spulen ausgeübten magnetischen Kräfte (Lorentz-Kräfte) als Funktion der Zeit und der Kurzschlußresistanz zu berechnen.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Electrical engineering 65 (1982), S. 233-239 
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Contents The diffusion of time varying magnetic fields through electrically conducting devices is numerically investigated. For this purpose a computer program was developed to compute the eddy currents induced in the walls of the device during the diffusion process, and their magnetic fields. The program is based on the finite element network method. By means of this approximation method the computation of diffusing magnetic fields is reduced to analysis of transient processes in electric networks. Given as a sample computation is a toroidal coil configuration typical of nuclear fusion experiments which is permeated in the vertical direction by an external, time varying magnetic field.
    Notes: Übersicht Die Diffusion zeitvarianter Magnetfelder durch elektrisch leitende Apparaturen wird numerisch untersucht. Dazu ist ein Computer-Programm entwickelt worden, mit dem die während des Diffusionsvorgangs in den Wänden der Apparatur induzierten Wirbelströme und deren Magnetfelder berechnet werden können. Das Programm basiert auf der sogenannten Finite-Element-Netzwerksmethode. Mit dieser Approximationsmethode wird die Berechnung diffundierender Magnetfelder auf die Analyse transienter Vorgänge in elektrischen Netzwerken zurückgeführt. Als Berechnungsbeispiel dient eine für Kernfusionsexperimente typische, toroidale Spulenanordnung, die von einem externen, zeitvarianten Magnetfeld in vertikaler Richtung durchdrungen wird.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Electrical engineering 62 (1980), S. 181-186 
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Contents The induction process induced in a toroidal vacuum vessel by sudden disruption of the plasma current is analyzed in the case of the ASDEX tokamak experiment by an approximation method. For this purpose the rotation symmetric vessel is regarded as parallel connected, circular, lossy conductors magnetically coupled with one another and with the plasma. The transient currents and voltages occurring in the network are numerically calculated. The current distribution in the vessel walls can then be given directly from these currents. In addition, the currents induced in the vessel walls are measured in a 1:10 model taking the necessary scaling factors into account. The experimental and calculated results are compared.
    Notes: Übersicht Der durch einen plötzlichen Abriß des Plasmastromes in einem ringförmigen Vakuumgefäß hervorgerufene Induktionsvorgang wird am Beispiel des Tokamak-Experimentes ASDEX mit Hilfe einer Approximations-Methode ana-lysiert. Dazu wird das rotationssymmetrische Gefäß als Parallelschaltung kreisfömiger, verlustbehafteter Leiter aufgefaßt, die miteinander und mit dem Plasma magnetisch gekoppelt sind. Die in diesem Netzwerk auftretenden transienten Ströme und Spannungen werden numerisch berechnet. Aus den Strömen kann unmittelbar die Stromverteilung in den Gefäßwänden angegeben werden. Außerdem wurden die Ströme in den Gefäßwänden gemessen. Hierzu diente ein Modell im Maßstab 1:10. Auf die Skalierungsfaktoren wird eingegangen. Die Ergebnisse aus Messung und Rechnung werden gegenübergestellt
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Electrical engineering 69 (1986), S. 359-365 
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Contents Tokamaks are toroidal experimental devices in which it is being attempted to achieved controlled nuclear fusion. This report describes investigations of the magnetic field diffusion through the vacuum vessel of the ASDEX Upgrade tokamak that occurs when there is sudden disruption of the plasma current. The eddy currents thereby generated in the vessel wall are numerically analysed in respect of their time behaviour and distribution. The vessel is also permeated by various magnetic fields, which, in conjunction with the eddy currents, produce magnetic forces. These forces are likewise calculated since they have a bearing on the design of the vessel.
    Notes: Übersicht Tokamaks sind torusförmig aufgebaute Experimentieranlagen, in denen man versucht, die kontrollierte Kernfusion zu erreichen. Für den Tokamak ASDEUX Upgrade wird die Magnetfelddiffusion durch sein Vakuumgefäß bei einem plötzlichen Abriß des Plasmastroms untersucht. Die dabei in der Gefäßwand erzeugten Wirbelströme werden hinsichtlich ihres zeitlichen Verhaltens und ihrer räumlichen Verteilung numerisch analysiert. Das Gefäß wird gleichzeitig von verschiedenen Magnetfeldern durchsetzt, die gemeinsam mit den Wirbelströmen magnetische Kräfte in der Gefäßwand verursachen. Diese Kräfte werden ebenfalls berechnet, da sie das Design des Gefäßes entscheidend beeinflussen.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 1556-1558 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The thermal outdiffusion of hydrogen from undoped ZnSe layers grown by metalorganic vapor phase epitaxy has been investigated. The samples were grown using dimethyl-zinc-triethylamine, di-tert.-butylselenide as precursors with hydrogen and nitrogen as carriergas. The typical atomic hydrogen concentrations of the samples is nH=1018 cm−3, which originates from pyrolysis products of the organometallic precursors. The incorporation from the carrier gas is negligible. Control samples grown by molecular beam epitaxy in the presence of atomic and molecular hydrogen in the growth chamber showed no hydrogen incorporation. The outdiffusion process was investigated using transient effusion experiments. The experiments are explained by diffusion controlled effusion with a diffusion coefficient of D(T)=1.4×10−11 exp[−0.33(±0.03) eV/(kBT)]cm2/s. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 5923-5925 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The morphology, atomic magnetic moments, and in-plane magnetic anisotropies of ultrathin bcc Fe(001) films deposited by molecular beam epitaxy on ZnSe epilayers grown on GaAs(001) single crystal are reported. The growth mode and structure have been determined in situ by means of reflection high energy electron diffraction and Auger electron spectroscopy. The magnetic properties were characterized ex situ by an alternating gradient magnetometer, superconducting quantum interference device (SQUID) magnetometry, and conversion electron Mössbauer spectroscopy (CEMS). The Fe growth is epitaxial and occurs by three dimensional nucleation at the beginning. The coalescence of the islands is observed around 7 monolayers (ML). In agreement with SQUID results, CEMS measurements indicate no reduction of the Fe magnetic moment compared to the bulk value even for the first Fe monolayers. Determination of the in-plane anisotropy constants as function of the Fe thickness shows a strong interface-induced uniaxial in-plane magnetic anisotropy, which leads to a continuous evolution from a pure uniaxial anisotropy with easy axis along [110] direction for thickness below 10 ML to the pure bulk cubic Fe anisotropy above 40 ML. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 2871-2875 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated CuInSe2 surfaces as well as the interfaces of the systems ZnSe/CuInSe2 and ZnS/CuInSe2 by vacuum ultraviolet photoelectron spectroscopy with synchrotron radiation. The CuInSe2 substrates are prepared with a hydrogen plasma and show high quality surfaces suitable for further growth of ZnSe in order to determine the valence-band offset of ZnSe/CuInSe2. At the surface of CuInSe2 Se atoms have been replaced by Te or S atoms, so that CuInTe2 or CuInS2 surfaces were formed. We determined the valence-band offsets of CuInTe2/CuInSe2 and CuInS2/CuInSe2 to be ΔEvb(CuInTe2/CuInSe2)=(0.85±0.05)eV and ΔEvb(CuInS2/CuInSe2)=(0.87±0.05)eV. ΔEvb(ZnSe/CuInSe2)=−(0.5±0.1)eV is in good agreement with values from literature. Furthermore we have examined the interface ZnS/CuInS2 and obtained the valence-band offset ΔEvb(ZnS/CuInS2)=−(2.3±0.1)eV. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0167-899X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Sozial- und Präventivmedizin 2 (1957), S. 397-408 
    ISSN: 1420-911X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Lead compounds are being largely distributed in the atmosphere by the consumption of leaded fuels in combustion engines. The particle size and shape of these compounds were determined, methods for their collection were investigated and lead concentrations in the air of streets and repair shops were tested. These investigations were accomplished by comparative determinations of lead contents in sedimented dusts from streets, repair shops and automotiv-free industrial plants, registrating the alteration of lead contents in the dust of streets during several years. Furthermore some tests concerning the retention of tetraethyl lead in the lung and the breathing tract were made.
    Notes: Zusammenfassung Durch den Verbrauch bleihaltigen Automobilbenzins gelangen Bleiverbindungen in weiter Verbreitung in die Luft. Teilchengröße und -gestalt dieser Verbindungen wurden bestimmt, Methoden zu ihrer Abscheidung untersucht und Bleikonzentrationen in der Luft von Straßen und Garagen ermittelt. Ergänzt wurden diese Untersuchungen durch vergleichende Bestimmungen der Bleigehalte in Sedimentstäuben von Straßen, Garagen und autofreien Gewerbebetrieben, wobei die Änderung der Bleigehalte im Straßenstaub über mehrere Jahre verfolgt wurde. Ferner wurden einige Versuche über die Retention von Bleitetraäthyldampf in Lunge und Atemwegen angestellt.
    Type of Medium: Electronic Resource
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