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[en] The characteristics of the corona onset of point-to-plane gap under negative steady potentials in air were studied using a quartz-lens camera, an electrometer, a Van de Graaf generator and an ocilloscope. The results indicated that the larger the point radius was, the more irregular coronas observed. As the gap length increases, the corona onset potential increased exponentially in the short range and increased linearly for the constant point radius and as a function of point radius for the fixed gap length. The corona current decreased as the gap length increased for the constant point radius while it increased as the point radius increased with the fixed gap length. As to the corona figure, we have also found that the axial length of stremers increased slowly for the increase of gap length. (Author)
[en] Inconsistency regarding the influence of Ar addition on ozone generation in a corona discharge has been found in relevant studies. Unlike in the literature to date, a dielectric barrier discharge (DBD) reactor is adopted in this study. In addition to clarifying whether using Ar as an additive would lead to different types of behavior in a DBD and a corona discharge, this study is also motivated to explore the possible causes leading to the inconsistency. The experimental results show that adding Ar into the O2 plasma would lead to the same influence on ozone generation in the DBD and corona discharge. Moreover, all types of controversial behavior caused by Ar addition reported in the relevant literature are observed in this study as well, indicating that the results of this study are comprehensive enough to interpret the inconsistency. By examining the experimental results in detail, it is found that the controversial influences of Ar addition on ozone generation were found using different assumptions. At a fixed applied voltage, the ozone generation might increase as the Ar concentration is increased, which results from a higher discharge power. Nevertheless, for a certain specific input energy (the ratio of discharge power to gas flow rate), the ozone concentration is lower as the Ar concentration is increased. Therefore, adding Ar is not a good way to enhance ozone generation from an economic point of view.
[en] An anomalous kind of the positive corona - a linear corona torch discharge - is investigated. The discharge is nearly steady-state and operates with various electrode configurations, e.g., wire-plane, needle-plane, wire-cylinder, and two or more wires placed in parallel. It is found that the discharge exists in the form of a pulsed corona or an ordinary positive corona, which alternatively change each other under the action of a spark-gap switch
[en] Corona discharges in gases exist under several distinctive forms. In this paper, a survey study has been made of ac corona discharge modes generated in some different gases fed in a wire-duct reactor with a constant rate of flowing at atmospheric pressure. The properties of different corona modes are analyzed under some condition transitions from Trichel pulses to a steady glow. In the course of the presented experimental work, numerous apparent contradictions with earlier observations necessitated further study and are given to provide more information on the physical mechanisms of the ac corona discharges. Furthermore, we have gained insight into some new technologies and applications of the environmentally friendly corona and plasma discharges.
[en] Some aspects of progress in laser fusion are briefly reviewed which indicate that experiments are on the threshold of entering a regime where nonlinear dynamics will become important. Recent studies of the general nonlinear force that include additional nonponderomotive terms are reviewed. Computer calculations that provide a detailed knowledge of the transfer of optical energy into a plasma corona by nonlinear forces are then described. Two key regimes are observed: 1) early production of fast moving cold blocks of plasma followed by 2) a decay of the corona where the plasma velocity obeys a Kortweg-de-Vries equation. 54 refs
[en] Monolayer Tungsten disulfide (WS2) shows unique optoelectronic properties and has potential applications in nanodevices. However, the stability of the monolayer WS2 exposed in the ambient condition should be evaluated and improved before its practical application. In this paper, we investigated the shape, structure, and luminescence of the monolayer WS2 under heating and corona discharge conditions in air. We show that monolayer WS2 without any coating film is unstable under such practical condition. To protect the monolayer, we covered a layer of polymethyl methacrylate (PMMA) on the surface of the monolayer WS2 and found the stability was improved. (paper)