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    Wyświetlanie 1-8 z 8
    Tytuł:
    Design and Reliability of a High Voltage, High Current Solid State Switch for Magnetic Forming Applications
    Autorzy:
    Welleman, A.
    Leutwyler, R.
    Gekenidis, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/1807871.pdf
    Data publikacji:
    2009-06
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    84.30.Jc
    84.32.Dd
    Opis:
    The presentation will give an overview of the design, construction, test and reliability of a solid state switch assembly used for magnetic forming applications. In 2005 a prototype of a reverse conducting semiconductor switch for 210 kA at 100 μs damped sine wave discharge and 21 kV dc was designed to be used in an experimental system at the Fraunhofer Institute at Chemnitz (Germany). The aim was to show the industry that semiconductors can be used for this type of applications. Precautions in the design stage have to be taken to reach high operational lifetime. The presented prototype switch was designed for an expected lifetime of 20 000 shots under nominal and 1 000 shots under short circuit conditions of 420 kA. After successful commissioning, further tests were done on separate semiconductor devices to verify under which conditions the lifetime could be increased to several million shots for the given application. For this verification, ABB has done extended device tests over more than one million shots and the wafers were analysed. The results of the reliability test are part of this presentation. It will be concluded that proper designed solid state switches are economically feasible, free from maintenance and despite higher initial cost are more reliable and superior to any other technology existing today.
    Źródło:
    Acta Physica Polonica A; 2009, 115, 6; 986-988
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of External Contacts on Edge Magnetic Moments in Graphene Nanoribbons
    Autorzy:
    Krompiewski, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/1386979.pdf
    Data publikacji:
    2015-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    72.80.Vp
    73.63.Rt
    84.32.Dd
    Opis:
    The main problem of interest of this study is the influence of external electrodes on the edge magnetic moments in graphene nanoribbons. The studies are carried out within the framework of tight-binding method (for π -state electrons) and the Landauer-Büttiker formalism combined with the Green function technique. It is shown that the edge atom moments get reduced (and eventually disappear) when the graphene nanoribbon/electrode interface becomes more and more transparent for electrons.
    Źródło:
    Acta Physica Polonica A; 2015, 127, 2; 523-524
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Electronic Transport in Multi-Terminal Graphene Devices with Various Arrangements of Electrodes
    Autorzy:
    Krompiewski, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/1201840.pdf
    Data publikacji:
    2014-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    72.80.Vp
    3.63.Rt
    84.32.Dd
    Opis:
    This study is devoted to the problem of electronic transport in graphene nanodevices in 4-terminal systems with various arrangements of electrodes. The electrodes are attached to square and rectangular graphene nanoflakes with armchair (a) and zigzag (z) edges. Apart from the known case of the zzzz-configuration, with all the electrodes coupled to the zigzag fragments of the edges, also the aaaa- and zaza-type cases are considered here. The adopted theoretical approach is based on a tight-binding method combined with the wideband approximation for electrodes, and an effective iterative knitting-type Green's function algorithm.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 1; 194-195
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    SN-series Pseudospark Switches, Operating Completely without Permanent Heating. New Prospects of Application in Pulsed Power
    Autorzy:
    Bochkov, V.
    Bochkov, D.
    Dyagilev, V.
    Ushich, V.
    Powiązania:
    https://bibliotekanauki.pl/articles/1807864.pdf
    Data publikacji:
    2009-06
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    52.75.-d
    52.77.Fv
    84.32.Dd
    52.75.Kq
    Opis:
    Since 1990s the process of exclusion of gas-discharge and vacuum switches (GDSs and VSs) from pulsed power systems has been conditioned by two major factors - insufficient service time and necessity to supply filament circuits of GDSs and VSs. In the report, design and long-term test results of pseudospark switches (PSSs) are presented. The PSSs are to a great extent free of the mentioned shortcomings; in particular, the switches are capable of operating without filament, providing a wide variety of perspective applications of the tubes in pulsed power.
    Źródło:
    Acta Physica Polonica A; 2009, 115, 6; 980-982
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Characterization of Nanocrystalline Cu25Mo Electrical Contact Material Synthesized via Ball Milling
    Autorzy:
    Biyik, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/1031886.pdf
    Data publikacji:
    2017-09
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    81.20.Ev
    84.32.Dd
    Opis:
    In this study, Cu-based Mo-doped composite powder was synthesized by ball milling technique. Elemental powder mixture containing 25 wt.% Mo was milled in a high-energy planetary-type ball mill to achieve homogeneously mixed composite powder. Characterization of the starting and the milled powders was carried out using scanning electron microscopy and laser diffraction analysis. It was found that particle size of powder had gradually decreased with increasing milling duration. scanning electron microscope pictures, corresponding to the later stages of milling process prove that nanocrystalline powders were obtained after milling duration of 30 h. Prolonged milling durations lead to powder contamination, which is undesirable for contact applications, where the purity is of big importance. Therefore, optimum milling duration was determined to be 30 h.
    Źródło:
    Acta Physica Polonica A; 2017, 132, 3; 886-888
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Fabrication and Arc-Erosion Behavior of Ag8SnO₂ Electrical Contact Materials under Inductive Loads
    Autorzy:
    Biyik, S.
    Aydin, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1030286.pdf
    Data publikacji:
    2017-03
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    81.20.Ev
    81.70.-q
    07.50.-e
    84.32.Dd
    Opis:
    In this study, Ag-based SnO₂-reinforced electrical contact materials were produced by powder metallurgy and mechanical alloying techniques. Elemental powder mixture containing 8 wt.% SnO₂ was milled in a high-energy planetary-type ball mill, to achieve homogeneously mixed composite powder, and subsequently pressed in a closed die to obtain green compacts with a cylindrical shape and then sintered under vacuum to obtain composites. Composites were then subjected to electrical wear tests under inductive loads to investigate the arc-erosion performance of electrical contacts. Surface deterioration and mass losses of electrical contacts were also evaluated, as a function of increasing switching number. Characterization of the starting and composite powders, green compacts, composites and arc-originated surface deterioration was carried out using scanning electron microscopy and energy-dispersive X-ray spectroscopy. It was found that powder particle size had decreased with the increasing milling time. Density and hardness values of the composites had increased, whereas porosity had decreased with the increasing sintering temperature. Optimum sintering temperature was determined as 900°C. The arc-affected zones became bigger with the increase of the number of switching operations. Furthermore, comparison between surface morphologies and mass losses of arc-eroded specimens had revealed that the stationary contacts exhibit higher rates of erosion than the movable contacts.
    Źródło:
    Acta Physica Polonica A; 2017, 131, 3; 339-342
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Investigation of the Effect of Different Current Loads on the Arc-Erosion Performance of Electrical Contacts
    Autorzy:
    Biyik, S.
    Aydin, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1186764.pdf
    Data publikacji:
    2016-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    81.70.-q
    07.50.-e
    84.32.Dd
    Opis:
    In this study, arc-erosion experiments using contactors were performed under inductive loads for up to 40000 switching operations to investigate the effect of different current loads on the arc-erosion performance of electrical contacts. Determination of the mass loss was performed after every 5000 operations. The arc-eroded surfaces were examined using scanning electron microscopy. The chemical composition near the arc was determined by energy dispersive X-ray spectroscopy. The results show that the contact surfaces are greatly affected by arc-erosion, resulting in mass loss due to material migration and/or evaporation. In addition, the arc-affected zones become bigger with the increase in the number of switching operations, especially at 20 A. However, electrical cleaning improves the contact performance by reducing the contact resistance due to breakdown of the non-conducting oxide films formed between 20000 and 25000 switching operations at 20 A. The stationary contacts experience major erosion, whereas the movable contacts suffered less contact erosion under each current load.
    Źródło:
    Acta Physica Polonica A; 2016, 129, 4; 656-660
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Optimization of Mechanical Alloying Parameters of Cu25W Electrical Contact Material
    Autorzy:
    Biyik, S.
    Aydin, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1031274.pdf
    Data publikacji:
    2017-09
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    81.20.Ev
    84.32.Dd
    Opis:
    In this study, the effect of mechanical alloying parameters, namely the effect of process control agent, ball-to-powder weight ratio and milling duration, on the synthesis of Cu25W composite powder was investigated. Planetary-type ball milling equipment was used to conduct mechanical alloying experiments. Stearic acid was used as the process control agent in order to establish a balance between cold welding and fracturing. The optimum amount of stearic acid was determined as a function of particle size and milling time at constant speed. By using this optimum amount of process control agent, three different ball-to-powder weight ratio values were also employed, and the effect of ball-to-powder weight ratio on particle size and morphology of Cu25W composite powders was investigated. The microstructural evolution of the milled powders was characterized using scanning electron microscopy and laser diffraction analysis. The test results have shown that the morphology and particle size distribution of the milled powders change significantly depending upon the milling parameters. In addition, higher ball-to-powder weight ratio values tend to lower the milling duration for the same amount of particle size reduction. However, particle size reduction suffers beyond the maximal value of ball-to-powder weight ratio, especially in the later stages of mechanical alloying.
    Źródło:
    Acta Physica Polonica A; 2017, 132, 3; 909-912
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-8 z 8

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