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Suche nach „[D.] [Wang]“ hat 8 Publikationen gefunden
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    NachhaltigElektrotechnik und Medientechnik

    Zeitschriftenartikel

    D. Liu, C. Liu, W. Ni, Y. Wang, H. Fan, Günther Benstetter, Y.-W. You, L. Liu, Q. Yang

    Nanostructured fuzz growth on tungsten under low-energy and high-flux He irradiation

    Scientific Reports (Nature Publishing Group), vol. 5, no. Article number: 10959, pp. 1-9

    2015

    DOI: 10.1038/srep10959

    NachhaltigElektrotechnik und Medientechnik

    Zeitschriftenartikel

    D. Liu, Tobias Berthold, W. Ni, Y. Wang, H. Fan, Günther Benstetter, L. Liu, Q. Yang

    Observation of interstitial loops in He+ irradiated W by conductive atomic force microscopy

    Acta Materialia, vol. 92, pp. 178-188

    2015

    NachhaltigAngewandte Naturwissenschaften und Wirtschaftsingenieurwesen

    Zeitschriftenartikel

    S. Liu, J. Sun, C. Sang, Thomas Stirner, S. Dai, D. Wang

    Molecular dynamics simulation of the formation, growth and bursting of bubbles in tungsten exposed to high fluxes of low energy deuterium

    Journal of Nuclear Materials - PLASMA-SURFACE INTERACTIONS 21 — Proceedings of the 21st International Conference on Plasma-Surface Interactions in Controlled Fusion Devices Kanazawa, Japan, May 26-30, 2014, vol. 463, no. August, pp. 363-366

    2015

    DOI: 10.1016/j.jnucmat.2014.12.060

    Abstract anzeigen

    Molecular dynamics simulations are carried out to investigate the formation, growth and bursting of bubbles in tungsten exposed to the irradiation of an extremely high deuterium flux. It is found that the bubbles form in the region near the location of the implanted ion distribution peaks, and that the effect of the substrate temperature on the bubble formation depth is negligible; it is also found that the percentage of deuterium that is found in D2 molecules increases as the bubble grows, and that the evolution of the bubble’s internal pressure is strongly associated with the properties of its surrounding structure. The simulations display the development of a dome-shaped structure at the tungsten surface during the bubble growth. The merging of two deuterium bubbles is also observed. The present simulations also show that the bubble bursts by generating a partially opened lid, which has already been observed in previous independent experiments.

    Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen

    Zeitschriftenartikel

    J. Sun, Thomas Stirner, D. Wang, Y. Fan, Y. Zou

    Investigation of the effects of a thin dielectric layer on low-pressure hydrogen capacitive discharges driven by combined radio frequency and pulse power sources

    Physics of Plasmas, vol. 20, no. 11

    2013

    DOI: 10.1063/1.4831775

    Abstract anzeigen

    Negative hydrogen ion sources, for instance for fusion devices, currently attract considerable attention. To generate the precursors—highly rovibrationally excited hydrogen molecules—for negative hydrogen ions effectively by electron excitation, a thin dielectric layer is introduced to cover the surface of the electrically grounded electrode of two parallel metal plates in a low-pressure hydrogen capacitive discharge driven by combined rf and pulse power sources. To understand the characteristics of such discharges, particle-in-cell simulations are conducted to study the effects that the single dielectric layer would bring onto the discharges. The simulation results show that the dielectric layer leads to a much higher plasma density and a much larger production rate of highly vibrationally excited hydrogen molecules compared to discharges without the dielectric layer on the electrode. Further investigation indicates that the nonlinear oscillation of the electrons induced by the nanosecond-pulse continues until it is finally damped down and does not show any dependence on the pulse plateau-time, which is in stark contrast to the case without the dielectric layer present. The physical reason for this phenomenon is explored and explained.

    Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen

    Zeitschriftenartikel

    J. Sun, Thomas Stirner, D. Wang, Y. Fan, Y. Zou

    Study of the effects of a transverse magnetic field on radio frequency argon discharges by two-dimensional particle-in-cell-Monte-Carlo collision simulations

    Physics of Plasmas, vol. 20, no. 10

    2013

    DOI: 10.1063/1.4826215

    Abstract anzeigen

    The influence of an applied magnetic field on plasma-related devices has a wide range of applications. Its effects on a plasma have been studied for years; however, there are still many issues that are not understoodwell. This paper reports a detailed kinetic study with thetwo-dimension-in-space and three-dimension-in-velocity particle-in-cellplus Monte Carlo collision method on the role of E×B drift in acapacitive argon discharge, similar to the experiment of You et al.[Thin Solid Films 519, 6981 (2011)]. The parameters chosen in the present study for the external magnetic field are in a range common tomany applications. Two basic configurations of the magnetic field areanalyzed in detail: the magnetic field direction parallel to theelectrode with or without a gradient. With an extensive parametricstudy, we give detailed influences of the drift on the collectivebehaviors of the plasma along a two-dimensional domain, which cannot berepresented by a 1 spatial and 3 velocity dimensions model. By analyzingthe results of the simulations, the occurring collisionless heating mechanism is explained well.

    Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen

    Zeitschriftenartikel

    L. Li, J. Bai, J. Sun, Thomas Stirner, D. Wang

    Particle simulation of the nonlinear oscillation of electrons induced by a nanosecond pulse in rf capacitive hydrogen discharges

    Physics of Plasmas, vol. 19, no. 3

    2012

    DOI: 10.1063/1.3695121

    Abstract anzeigen

    A particle-in-cell simulation was employed to investigate the nature and physical cause of the nonlinear oscillation of electrons induced by a nanosecond pulse in rf capacitive hydrogen discharges. It was found that the applied nanosecond pulse converted the plasma quickly from the bi-Maxwellian equilibrium formed in the rf capacitive discharge into another temporal bi-Maxwellian equilibrium. When the applied electric field collapses within a few nanoseconds, the electric field arising from the space charge serves as a restoring force to generate a swift oscillation of the electrons. The energy stored in the plasma is converted gradually into the chemical energy during the electron periodic movement. It is also found that the rise-, plateau-, and fall-times of the applied pulse affect the evolution of the electron energy distribution. The collective electron oscillation has a repetition frequency approximately equal to the electron plasma frequency, independent of pulse rise-, plateau-, and fall-times. This oscillation of electrons induced by a nanosecond pulse can be used to generate highly excited vibrational states of hydrogen molecules, which are a necessary precursor for negative hydrogen ions.

    Elektrotechnik und Medientechnik

    Zeitschriftenartikel

    D. Liu, Günther Benstetter, J. Zhang, W. Wang

    Effect of pressure on the deposition of hydrogen-free amorphous carbon and carbon nitride films by the pulsed cathodic arc discharge method

    Journal of Vacuum Science & Technology A, vol. 22

    2004

    DOI: 10.1116/1.1798691

    Abstract anzeigen

    Hydrogen-free amorphous carbon and carbon nitride films were deposited using the pulsed cathodic arc discharge at different argon and nitrogen pressures. The surface and mechanical properties of these films were found to strongly depend on the gas pressure. The tetrahedral amorphous carbon and hard films with smooth surfaces (rms roughness: ) were prepared at lower gas pressures. Incorporation of an increasing amount of nitrogen in films caused a decrease in filmhardness. All the films were covered with the thin graphite-like surface layers. The filmhardness was correlated to the soft surface layer thickness, and the films with thinner surface layers exhibit higher hardness. The mean energies of pulsed plasma beams were measured as the functions of argon and nitrogen pressures. The mean energies of plasma beams decrease in an exponential fashion with increasing gas pressure due to the carbon ion collisions with the neutral gas species. The effects of mean energies of deposited species on the filmdeposition were explained in terms of the thermal spike migration of surface atoms. The formation of graphite-like surface layers is associated with the low-energy deposition process. The low-energy species diffusing on filmsurface lead to the formation of graphite-like films with plenty of grains. The higher-energy species may produce the strong thermal spike at filmsurface, and contribute to the formation of bonded structure at a bonded matrix.

    Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen

    Zeitschriftenartikel

    J. Sun, Thomas Stirner, D. Wang

    A kinetic study of ozone and nitric oxides in dielectric barrier discharges for O2/NOx mixtures

    Plasma Science & Technology, vol. 4, pp. 1227-1238

    2002

    DOI: 10.1088/1009-0630/4/2/008

    Abstract anzeigen

    A simple model is described to simulate kinetic processes in dielectric barrier discharges for O2/NOx mixtures. A threshold of ozone production found experimentally is confirmed by the calculations of this modeling, and the underlying chemical reaction mechanisms are discussed. It is also found that the effects of diffusion processes in the period of the lifetime of O atoms are not important to microdischarge channels with a large radius, i.e. larger than 150 μm.