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Sample records for pulsed dc reactive

  1. Aluminum oxide films deposited in low pressure conditions by reactive pulsed dc magnetron sputtering

    CERN Document Server

    Seino, T

    2002-01-01

    The reactive pulsed dc sputtering technique is widely used for the deposition of oxide films. The operating pressure for sputtering is commonly above 0.13 Pa. In this study, however, aluminum oxide (alumina) films were deposited at operating pressures from 0.06 to 0.4 Pa using a sputtering system equipped with a scanning magnetron cathode and a pulsed dc power supply. The pulsed dc power was found to be useful not only to reduce arcing, but also to sustain the discharge at low pressure. The electrical breakdown field, intrinsic stress, O/Al ratio, refractive index, and surface roughness were investigated. Both a low intrinsic stress and an O/Al ratio around the stoichiometry were required to get the film having a high breakdown field. A low operating pressure of 0.1 Pa was found to provide the necessary stress and O/Al ratio targets. A 50-nm-thick alumina film having a maximum breakdown field of 7.4 MV/cm was obtained.

  2. Bonding structure and morphology of chromium oxide films grown by pulsed-DC reactive magnetron sputter deposition

    Energy Technology Data Exchange (ETDEWEB)

    Gago, R., E-mail: rgago@icmm.csic.es [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, E-28049 Madrid (Spain); Vinnichenko, M. [Fraunhofer-Institut für Keramische Technologien und Systeme IKTS, D-01277 Dresden (Germany); Hübner, R. [Helmholtz-Zentrum Dresden – Rossendorf, Institute of Ion Beam Physics and Materials Research, Bautzner Landstraße 400, 01328 Dresden (Germany); Redondo-Cubero, A. [Departamento de Física Aplicada and Centro de Microanálisis de Materiales, Universidad Autónoma de Madrid, E-28049 Madrid (Spain)

    2016-07-05

    Chromium oxide (CrO{sub x}) thin films were grown by pulsed-DC reactive magnetron sputter deposition in an Ar/O{sub 2} discharge as a function of the O{sub 2} fraction in the gas mixture (ƒ) and for substrate temperatures, T{sub s}, up to 450 °C. The samples were analysed by Rutherford backscattering spectrometry (RBS), spectroscopic ellipsometry (SE), atomic force microscopy (AFM), scanning (SEM) and transmission (TEM) electron microscopy, X-ray diffraction (XRD), and X-ray absorption near-edge structure (XANES). On unheated substrates, by increasing ƒ the growth rate is higher and the O/Cr ratio (x) rises from ∼2 up to ∼2.5. Inversely, by increasing T{sub s} the atomic incorporation rate drops and x falls to ∼1.8. XRD shows that samples grown on unheated substrates are amorphous and that nanocrystalline Cr{sub 2}O{sub 3} (x = 1.5) is formed by increasing T{sub s}. In amorphous CrO{sub x}, XANES reveals the presence of multiple Cr environments that indicate the growth of mixed-valence oxides, with progressive promotion of hexavalent states with ƒ. XANES data also confirms the formation of single-phase nanocrystalline Cr{sub 2}O{sub 3} at elevated T{sub s}. These structural changes also reflect on the optical and morphological properties of the films. - Highlights: • XANES of CrO{sub x} thin films grown by pulsed-DC reactive magnetron sputtering. • Identification of mixed-valence amorphous CrO{sub x} oxides on unheated substrates. • Promotion of amorphous chromic acid (Cr{sup VI}) by increasing O{sub 2} partial pressure. • Production of single-phase Cr{sub 2}O{sub 3} films by increasing substrate temperature. • Correlation of bonding structure with morphological and optical properties.

  3. Deposition of PZT thin film onto copper-coated polymer films by mean of pulsed-DC and RF-reactive sputtering

    Czech Academy of Sciences Publication Activity Database

    Suchaneck, G.; Labitzke, R.; Adolphi, B.; Jastrabík, Lubomír; Adámek, Petr; Drahokoupil, Jan; Hubička, Zdeněk; Kiselev, D.A.; Kholkin, A. L.; Gerlach, G.; Dejneka, Alexandr

    2011-01-01

    Roč. 205, č. 2 (2011), S241-S244 ISSN 0257-8972 R&D Projects: GA ČR GC202/09/J017; GA AV ČR KAN301370701; GA MŠk(CZ) 1M06002 Institutional research plan: CEZ:AV0Z10100522 Keywords : pulsed DC reactive sputtering * RF reactive sputtering * complex oxide film deposition * polymer substrate Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.867, year: 2011

  4. Polarity inversion of AlN film grown on nitrided a-plane sapphire substrate with pulsed DC reactive sputtering

    Directory of Open Access Journals (Sweden)

    Marsetio Noorprajuda

    2018-04-01

    Full Text Available The effect of oxygen partial pressure (PO2 on polarity and crystalline quality of AlN films grown on nitrided a-plane sapphire substrates by pulsed direct current (DC reactive sputtering was investigated as a fundamental study. The polarity inversion of AlN from nitrogen (−c-polarity to aluminum (+c-polarity occurred during growth at a high PO2 of 9.4×103 Pa owing to Al-O octahedral formation at the interface of nitrided layer and AlN sputtered film which reset the polarity of AlN. The top part of the 1300 nm-thick AlN film sputtered at the high PO2 was polycrystallized. The crystalline quality was improved owing to the high kinetic energy of Al sputtered atom in the sputtering phenomena. Thinner AlN films were also fabricated at the high PO2 to eliminate the polycrystallization. For the 200 nm-thick AlN film sputtered at the high PO2, the full width at half-maximum values of the AlN (0002 and (10−12 X-ray diffraction rocking curves were 47 and 637 arcsec, respectively.

  5. Pulsed-DC selfsputtering of copper

    International Nuclear Information System (INIS)

    Wiatrowski, A; Posadowski, W M; Radzimski, Z J

    2008-01-01

    At standard magnetron sputtering conditions (argon pressure ∼0.5 Pa) inert gas particles are often entrapped in the formed films. Inert gas contamination can be eliminated by using the self-sustained magnetron sputtering process because it is done in the absence of the inert gas atmosphere. The self-sustained sputtering (SSS) gives also a unique condition during the transport of sputtered particles to the substrate. It is especially useful for filling high aspect ratio submicron scale structures for microelectronics. So far it has been shown that the self-sputtering process can be sustained in the DC operation mode (DC-SSS) only. The main disadvantage of DC-SSS process is instability related to possible arc formation. Usage of pulsed sputtering, similarly to reactive pulsed magnetron sputtering, could eliminate this problem. In this paper results of pulsed-DC self-sustained magnetron sputtering (pulsed DC-SSS) of copper are presented for the first time. The planar magnetron equipped with a 50 mm in diameter and 6 mm thick copper target was powered by DC-power supply modulated by power switch. The maximum target power was about 11 kW (∼550W/cm 2 ). The magnetron operation was investigated as a function of pulsing frequency (20-100 kHz) and duty factor (50-90%). The discharge extinction pressure was determined for these conditions. The plasma emission spectra (400-410nm range) and deposition rates were observed for both DC and pulsed DC sustained self-sputtering processes. The presented results illustrate that stable pulsed DC-SSS process can be obtained at pulsing frequency in the range of 60-100 kHz and duty factor of 70-90%

  6. Pulsed-DC selfsputtering of copper

    Science.gov (United States)

    Wiatrowski, A.; Posadowski, W. M.; Radzimski, Z. J.

    2008-03-01

    At standard magnetron sputtering conditions (argon pressure ~0.5 Pa) inert gas particles are often entrapped in the formed films. Inert gas contamination can be eliminated by using the self-sustained magnetron sputtering process because it is done in the absence of the inert gas atmosphere. The self-sustained sputtering (SSS) gives also a unique condition during the transport of sputtered particles to the substrate. It is especially useful for filling high aspect ratio submicron scale structures for microelectronics. So far it has been shown that the self-sputtering process can be sustained in the DC operation mode (DC-SSS) only. The main disadvantage of DC-SSS process is instability related to possible arc formation. Usage of pulsed sputtering, similarly to reactive pulsed magnetron sputtering, could eliminate this problem. In this paper results of pulsed-DC self-sustained magnetron sputtering (pulsed DC-SSS) of copper are presented for the first time. The planar magnetron equipped with a 50 mm in diameter and 6 mm thick copper target was powered by DC-power supply modulated by power switch. The maximum target power was about 11 kW (~550W/cm2). The magnetron operation was investigated as a function of pulsing frequency (20-100 kHz) and duty factor (50-90%). The discharge extinction pressure was determined for these conditions. The plasma emission spectra (400-410nm range) and deposition rates were observed for both DC and pulsed DC sustained self-sputtering processes. The presented results illustrate that stable pulsed DC-SSS process can be obtained at pulsing frequency in the range of 60-100 kHz and duty factor of 70-90%.

  7. Pulsed dc self-sustained magnetron sputtering

    International Nuclear Information System (INIS)

    Wiatrowski, A.; Posadowski, W. M.; Radzimski, Z. J.

    2008-01-01

    The magnetron sputtering has become one of the commonly used techniques for industrial deposition of thin films and coatings due to its simplicity and reliability. At standard magnetron sputtering conditions (argon pressure of ∼0.5 Pa) inert gas particles (necessary to sustain discharge) are often entrapped in the deposited films. Inert gas contamination can be eliminated during the self-sustained magnetron sputtering (SSS) process, where the presence of the inert gas is not a necessary requirement. Moreover the SSS process that is possible due to the high degree of ionization of the sputtered material also gives a unique condition during the transport of sputtered particles to the substrate. So far it has been shown that the self-sustained mode of magnetron operation can be obtained using dc powering (dc-SSS) only. The main disadvantage of the dc-SSS process is its instability related to random arc formation. In such case the discharge has to be temporarily extinguished to prevent damaging both the magnetron source and power supply. The authors postulate that pulsed powering could protect the SSS process against arcs, similarly to reactive pulsed magnetron deposition processes of insulating thin films. To put this concept into practice, (i) the high enough plasma density has to be achieved and (ii) the type of pulsed powering has to be chosen taking plasma dynamics into account. In this article results of pulsed dc self-sustained magnetron sputtering (pulsed dc-SSS) are presented. The planar magnetron equipped with a 50 mm diameter and 6 mm thick copper target was used during the experiments. The maximum target power was about 11 kW, which corresponded to the target power density of ∼560 W/cm 2 . The magnetron operation was investigated as a function of pulse frequency (20-100 kHz) and pulse duty factor (50%-90%). The discharge (argon) extinction pressure level was determined for these conditions. The plasma emission spectra (400-410 nm range) and deposition

  8. Optical emission and mass spectroscopy of plasma processes in reactive DC pulsed magnetron sputtering of aluminium oxide

    Czech Academy of Sciences Publication Activity Database

    Novotný, Michal; Bulíř, Jiří; Pokorný, Petr; Bočan, Jiří; Fitl, Přemysl; Lančok, Ján; Musil, Jindřich

    2010-01-01

    Roč. 12, č. 3 (2010), 697-700 ISSN 1454-4164 R&D Projects: GA AV ČR IAA100100718; GA AV ČR KAN400100653; GA ČR GP202/09/P324 Institutional research plan: CEZ:AV0Z10100522 Keywords : reactive magnetron sputtering * alumina * plasma spectroscopy * mass spectroscopy * optical emission spectroscopy Subject RIV: BH - Optics, Masers, Lasers Impact factor: 0.412, year: 2010

  9. A comparison of reactive plasma pre-treatments on PET substrates by Cu and Ti pulsed-DC and HIPIMS discharges

    Energy Technology Data Exchange (ETDEWEB)

    Audronis, M., E-mail: m.audronis@yahoo.co.uk [Gencoa Ltd, Physics Road, Speke, Liverpool, L24 9HP (United Kingdom); Hinder, S.J. [The Surface Analysis Laboratory, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, GU2 7XH (United Kingdom); Mack, P. [ThermoFisher Scientific Ltd, Imberhorne Lane, East Grinstead, Sussex, RH19 1UB (United Kingdom); Bellido-Gonzalez, V. [Gencoa Ltd, Physics Road, Speke, Liverpool, L24 9HP (United Kingdom); Bussey, D.; Matthews, A. [Department of Engineering Materials, University of Sheffield, Sheffield S1 3JD (United Kingdom); Baker, M.A. [The Surface Analysis Laboratory, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, GU2 7XH (United Kingdom)

    2011-12-30

    PET web samples have been treated by magnetically enhanced glow discharges powered using either medium frequency pulse direct current (p-DC) or low frequency high power pulse (HIPIMS) sources. The plasma pre-treatment processes were carried out in an Ar-O{sub 2} atmosphere using either Cu or Ti sputter targets. XPS, AFM and sessile drop water contact angle measurements have been employed to examine changes in surface chemistry and morphology for different pre-treatment process parameters. Deposition of metal oxide onto the PET surface is observed as a result of the sputter magnetron-based glow discharge web treatment. Using the Cu target, both the p-DC and HIPIMS processes result in the formation of a thin CuO layer (with a thickness between 1 and 11 nm) being deposited onto the PET surface. Employing the Ti target, both p-DC and HIPIMS processes give rise to a much lower concentration of Ti (< 5 at.%), in the form of TiO{sub 2} on the PET treated surface. The TiO{sub 2} is probably distributed as an island-like distribution covering the PET surface. Presence of Cu and Ti oxide constituents on the treated PET is beneficial in aiding the adhesion but alone (i.e. without oxygen plasma activation) is not enough to provide very high levels of hydrophilicity as is clear from sessile drop water contact angle measurements on aged samples. Exposure to the plasma treatments leads to a small amount of roughening of the substrate surface, but the average surface roughness in all cases is below 2.5 nm. The PET structure at the interface with a coating is mostly or wholly preserved. The oxygen plasma treatment, metal oxide deposition and surface roughening resulting from the HIPIMS and p-DC treatments will promote adhesion to any subsequent thin film that is deposited immediately following the plasma treatment.

  10. Pulse-width modulated DC-DC power converters

    CERN Document Server

    Kazimierczuk, Marian K

    2008-01-01

    This book studies switch-mode power supplies (SMPS) in great detail. This type of converter changes an unregulated DC voltage into a high-frequency pulse-width modulated (PWM) voltage controlled by varying the duty cycle, then changes the PWM AC voltage to a regulated DC voltage at a high efficiency by rectification and filtering. Used to supply electronic circuits, this converter saves energy and space in the overall system. With concept-orientated explanations, this book offers state-of-the-art SMPS technology and promotes an understanding of the principle operations of PWM converters,

  11. DC motor operation controlled from a DC/DC power converter in pulse mode with low duty cycle

    OpenAIRE

    Stefanov, Goce; Kukuseva, Maja; Citkuseva Dimitrovska, Biljana

    2016-01-01

    In this paper pulse mode of operation of DC motor controlled by DC/DC power converter is analyzed. DC motor operation with time intervals in which the motor operates without output load is of interest. In this mode it is possible the motor to restore energy. Also, in the paper are represented calculations for the amount of the restored energy in the pulse mode operation of the motor for different duty cycles.

  12. Efficiency Enhancement in DC Pulsed Gas Discharge Memory Panel

    Science.gov (United States)

    Okamoto, Yukio

    1983-01-01

    Much improvement in the luminous efficiency of a dc pulsed gas discharge memory panel for color TV display was achieved by shortening the sustaining pulse duration. High energy electrons can thus be produced in the pulsed discharge with fast rise times. Calculated optimum value of E/P in a Xe gas discharge is 7-8 V/cm\\cdotTorr.

  13. Economical hydrogen production by electrolysis using nano pulsed DC

    Energy Technology Data Exchange (ETDEWEB)

    Dharmaraj, C.H. [Tangedco, Tirunelveli, ME Environmental Engineering (India); Adshkumar, S. [Department of Civil Engineering, Anna University of Technology Tirunelveli, Tirunelveli - 627007 (India)

    2012-07-01

    Hydrogen is an alternate renewable eco fuel. The environmental friendly hydrogen production method is electrolysis. The cost of electrical energy input is major role while fixing hydrogen cost in the conventional direct current Electrolysis. Using nano pulse DC input makes the input power less and economical hydrogen production can be established. In this investigation, a lab scale electrolytic cell developed and 0.58 mL/sec hydrogen/oxygen output is obtained using conventional and nano pulsed DC. The result shows that the nano pulsed DC gives 96.8 % energy saving.

  14. Controlling DC-DC converters by chaos-based pulse width modulation to reduce EMI

    International Nuclear Information System (INIS)

    Li Hong; Zhang Bo; Li Zhong; Halang, Wolfgang A.; Chen Guanrong

    2009-01-01

    In this paper, periodic and chaotic behaviors of DC-DC converters under certain parametric conditions are simulated, experimentally verified, and analyzed. Motivated by the work of J.H.B. Deane and D.C. Hamill in 1996, where chaotic phenomena are useful in suppressing electromagnetic interference (EMI) by adjusting the parameters of the DC-DC converter and making it operate in chaos, a chaos-based pulse width modulation (CPWM) is proposed to distribute the harmonics of the DC-DC converters continuously and evenly over a wide frequency range, thereby reducing the EMI. The output waves and spectral properties of the EMI are simulated and analyzed as the carrier frequency or amplitude changes with regard to different chaotic maps. Simulation and experimental results are given to illustrate the effectiveness of the proposed CPWM, which provides a good example of applying chaos theory in engineering practice.

  15. Properties of DLC coatings deposited by dc and dc with superimposed pulsed vacuum arc

    International Nuclear Information System (INIS)

    Zavaleyev, V.; Walkowicz, J.; Aksyonov, D.S.; Luchaninov, A.A.; Reshetnyak, E.N.; Strel'nitskij, V.E.

    2014-01-01

    Comparative studies of the structure, mechanical and tribological properties of DLC coatings deposited in DC and DC with superimposed high current pulse modes of operation vacuum-arc plasma source with the graphite cathode are presented. Imposition the pulses of high current on DC vacuum-arc discharge allows both increase the deposition rate of DLC coating and reduce the residual compressive stress in the coatings what promotes substantial improvement the adhesion to the substrate. Effect of vacuum arc plasma filtration with Venetian blind filter on the deposition rate and tribological characteristics of the coatings analyzed.

  16. Pulsed energy conversion with a dc superconducting magnet

    International Nuclear Information System (INIS)

    Cowan, M.; Cnare, E.C.; Leisher, W.B.; Tucker, W.K.; Wessenberg, D.L.

    1976-01-01

    A generator system for pulsed power is described which employs a dc superconducting magnet in a magnetic flux compression scheme. Experience with a small-scale generator together with projections of numerical models indicate potential applications to fusion research and commercial power generation. When the system is large enough pulse energy can exceed that stored in the magnet and pulse rise time can range from several microseconds to tens of milliseconds. (author)

  17. Laboratory manual for pulse-width modulated DC-DC power converters

    CERN Document Server

    Kazimierczuk, Marian K

    2015-01-01

    Designed to complement a range of power electronics study resources, this unique lab manual helps students to gain a deep understanding of the operation, modeling, analysis, design, and performance of pulse-width modulated (PWM) DC-DC power converters.  Exercises focus on three essential areas of power electronics: open-loop power stages; small-signal modeling, design of feedback loops and PWM DC-DC converter control schemes; and semiconductor devices such as silicon, silicon carbide and gallium nitride. Meeting the standards required by industrial employers, the lab manual combines program

  18. Study of general digital DC/pulse neutron generator

    International Nuclear Information System (INIS)

    Li Gang; Liu Zheng; Li Wensheng; Liu Hanlin; Liu Linmao

    2014-01-01

    Preliminary experimental results of digital DC/pulse neutron generator based on a ceramic drive-in target neutron tube for explosives detection are presented. The generator is a portable and on-off neutron source, and it can be controlled by remote PC. The generator can produce DC neutrons, pulse neutrons and multiple pulse neutrons. The maximum neutron yield is about 2 × 10"8 n/s, the minimum pulse width is 10 μs and the maximum pulse frequency is 10 kHz. Neutron yield and time-spectrum is measured in China Academy of Engineering Physics. The generator is suitable for explosive detection with PFTNA technology, and it can be used in other areas such as reactor measurements and on-line industrial test systems. (authors)

  19. Reactive pulsed laser deposition with gas jet

    International Nuclear Information System (INIS)

    Rakowski, R.; Bartnik, A.; Fiedorowicz, H.; Jarocki, R.; Kostecki, J.; Szczurek, M.

    2001-01-01

    Different metal (Sn, Al, steel, Cu, W) thin films were synthesized by reactive pulsed laser deposition on steel, copper and glass wafers. In our work pulsed Nd:glass (10 J, 800μs) laser system was used. Jet of gas was created by electromagnetic valve perpendicularly to the laser beam. Nitrogen, oxygen and argon were used. We used several to tens laser shots to obtain visible with the naked eye layers. Thin layers were observed under an optical microscope. (author)

  20. Pulse-Width-Modulating Driver for Brushless dc Motor

    Science.gov (United States)

    Salomon, Phil M.

    1991-01-01

    High-current pulse-width-modulating driver for brushless dc motor features optical coupling of timing signals from low-current control circuitry to high-current motor-driving circuitry. Provides high electrical isolation of motor-power supply, helping to prevent fast, high-current motor-driving pulses from being coupled through power supplies into control circuitry, where they interfere with low-current control signals.

  1. RF-superimposed DC and pulsed DC sputtering for deposition of transparent conductive oxides

    International Nuclear Information System (INIS)

    Stowell, Michael; Mueller, Joachim; Ruske, Manfred; Lutz, Mark; Linz, Thomas

    2007-01-01

    Transparent conductive oxide films are widely used materials for electronic applications such as flat panel displays and solar cells. The superposition of DC and pulsed DC power by a certain fraction of RF power was applied to deposit indium tin oxide films. This technique allows an additional tuning of different parameters relevant to film growth, and yields high quality films even under kinetically limited conditions. A long-term stable RF/DC process could be realized by using different combinations of standard power supply components, which includes a fully reliable arc handling system for both the RF and DC generators. The effectiveness of the arc handling system is illustrated by the current and voltage behavior recorded for actual arcing events. The resistivity of indium tin oxide films is strongly influenced by the respective sputtering mode. The best resistivity values of 145-148 μΩ cm were obtained by RF-superimposed pulsed DC sputtering at a pulse frequency between 100 and 200 kHz and a substrate temperature as low as 140 deg. C. In addition, the films were extremely smooth with a surface roughness of 1-2.5 nm

  2. Optical transponder DC probe [for pulsed power generator

    CERN Document Server

    Thompson, M C

    1999-01-01

    The Atlas Pulse Power, Marx Bank will produce significant electromagnetic interference potential (EMI) via its 192 spark-gaps and trigger systems (36 more spark gaps). The authors have a need to measure DC charge components to a fair degree of accuracy during charge to ensure a safe and balanced system. Isolation from elevated- deck and/or high EMI environments during DC voltage or current measurement has classically been approached using frequency modulation (FM) of an imposed carrier on an optical fiber coupled system. There are shortcomings in most systems that can generally be compensated for by various means. In their application of remote sensing, the power to run this remote probe was a central issue. As such the authors took another approach to monitor the DC charge record for the Atlas' Marx banks. (0 refs).

  3. Zero-voltage DC/DC converter with asymmetric pulse-width modulation for DC micro-grid system

    Science.gov (United States)

    Lin, Bor-Ren

    2018-04-01

    This paper presents a zero-voltage switching DC/DC converter for DC micro-grid system applications. The proposed circuit includes three half-bridge circuit cells connected in primary-series and secondary-parallel in order to lessen the voltage rating of power switches and current rating of rectifier diodes. Thus, low voltage stress of power MOSFETs can be adopted for high-voltage input applications with high switching frequency operation. In order to achieve low switching losses and high circuit efficiency, asymmetric pulse-width modulation is used to turn on power switches at zero voltage. Flying capacitors are used between each circuit cell to automatically balance input split voltages. Therefore, the voltage stress of each power switch is limited at Vin/3. Finally, a prototype is constructed and experiments are provided to demonstrate the circuit performance.

  4. Crystalline silicon films grown by pulsed dc magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Reinig, Peter; Fenske, Frank; Fuhs, Walther; Selle, Burkhardt [Hahn-Meitner-Institut Berlin, Abt. Silizium-Photovoltaik, Kekulestr. 5, D-12489 Berlin (Germany)

    2002-04-01

    Pulsed dc magnetron sputtering is used as a novel method for the deposition of crystalline silicon films on glass substrates. Hydrogen-free polycrystalline Si-films are deposited with high deposition rates at temperatures of 400-450 C and pulse frequencies f in the range 0-250 kHz. Strong preferential (100) orientation of the crystallites is observed with increasing f. High frequency and similarly high negative substrate bias cause an increase of the Ar content and an enhancement of structural disorder. Measurements of the transient floating potential suggest that the observed structural effects are related to bombardment of the growing film by Ar{sup +} ions of high energy.

  5. Isolated PDM and PWM DC-AC SICAMs[Pulse Density Modulated; Pulse Width Modulated

    Energy Technology Data Exchange (ETDEWEB)

    Ljusev, P.

    2004-03-15

    In this report a class of isolated PDM and PWM DC-AC SICAMs is described, which introduce the audio reference only in the output stage. AC-DC power supply is implemented in its simplest form: diode rectifier followed by a medium-size charge-storage capacitor. Isolation from the AC mains is achieved using a high frequency (HF) transformer, receiving the HF voltage pulses from the input 'inverter' stage and transferring them to the output 'rectifier+inverter' stage, which can use either PDM or PWM. The latter stage is then interfaced to the load using an output low-pass filter. Each of the dedicated stages is discussed in detail. Measurements on the master/slave PWM DC-AC SICAM prototype are presented to help benchmarking the performance of this class of SICAMs and identify the advantages and drawbacks. (au)

  6. Performance analysis of pulse analog control schemes for LLC resonant DC/DC converters suitable in portable applications

    Directory of Open Access Journals (Sweden)

    P. Kowstubha

    2016-12-01

    Full Text Available Performance Analysis of Pulse Analog Control Schemes, predominantly Pulse-Width Modulation (PWM and Pulse-Position Modulation (PPM for LLC resonant DC/DC converter suitable in portable applications is addressed in this paper. The analysis is done for closed loop performance, frequency domain performance, primary and secondary side conduction losses and soft commutation using PSIM 6.0 software and observed that PPM scheme provides better performance at high input voltage with a good selectivity of frequency over a wide range of line and load variations. The performance of LLC resonant DC/DC converter is demonstrated using PPM scheme for a design specifications of 12 V, 5 A output.

  7. Effect of DC voltage pulses on memristor behavior.

    Energy Technology Data Exchange (ETDEWEB)

    Evans, Brian R.

    2013-10-01

    Current knowledge of memristor behavior is limited to a few physical models of which little comprehensive data collection has taken place. The purpose of this research is to collect data in search of exploitable memristor behavior by designing and implementing tests on a HP Labs Rev2 Memristor Test Board. The results are then graphed in their optimal format for conceptualizing behavioral patterns. This series of experiments has concluded the existence of an additional memristor state affecting the behavior of memristors when pulsed with positively polarized DC voltages. This effect has been observed across multiple memristors and data sets. The following pages outline the process that led to the hypothetical existence and eventual proof of this additional state of memristor behavior.

  8. SWITCH MODE PULSE WIDTH MODULATED DC-DC CONVERTER WITH MULTIPLE POWER TRANSFORMERS

    DEFF Research Database (Denmark)

    2009-01-01

    A switch mode pulse width modulated DC-DC power converter comprises at least one first electronic circuit on a input side (1) and a second electronic circuit on a output side (2). The input side (1) and the output side (2) are coupled via at least two power transformers (T1, T2). Each power...... transformer (T1, T2) comprises a first winding (T1a, T2a) arranged in a input side converter stage (3, 4) on the input side (1) and a second winding (T1 b, T2b) arranged in a output side converter stage (5) on the output side (2), and each of the windings (T1a, T1 b, T2a, T2b) has a first end and a second end....... The first electronic circuit comprises terminals (AO, A1) for connecting a source or a load, at least one energy storage inductor (L) coupled in series with at least one of the first windings (T1a, T2a) of the power transformers (T1, T2), and for each power transformer (T1, T2), an arrangement of switches...

  9. Study of the mechanisms of flux enhancement through hairless mouse skin by pulsed DC iontophoresis

    International Nuclear Information System (INIS)

    Pikal, M.J.; Shah, S.

    1991-01-01

    Enhanced iontophoretic transport using pulsed DC is usually explained by citing the observed decrease in skin resistance caused by an increase in AC pulse frequency at very small currents. Alternately, it has been suggested that the on-to-off nature of pulsed DC imparts an impact energy to the fluid, thereby increasing transport. This report provides a test of these mechanisms for enhanced delivery via pulsed iontophoresis. The DC resistance of hairless mouse skin during continuous and pulsed DC iontophoresis is measured as a function of time for selected pulse frequencies and duty cycles using current densities ranging from 0.1 to 1.0 mA/cm2. As a test of the impact energy mechanism, the iontophoretic transport of 14C-glucose measured with pulsed DC is compared with similar data obtained previously using continuous DC. It is suggested that pulsed current can yield lower resistance and enhanced drug delivery provided that (a) the steady-state current during the on phase of the pulse is very small and (b) the frequency is low enough to allow depolarization of the skin during the off phase of the pulse. The glucose transport results suggest that the impact energy concept does not apply to iontophoresis

  10. Reduction of DC-link Capacitor in Case of Cascade Multilevel Converters by means of Reactive Power Control

    DEFF Research Database (Denmark)

    Gohil, Ghanshyamsinh Vijaysinh; Wang, Huai; Liserre, Marco

    2014-01-01

    A method to selectively control the amount of dc link voltage ripple by processing desired reactive power by a DC/DC converter in isolated AC/DC or AC/DC/AC system is proposed. The concept can reduce the dc link capacitors used for balancing the input and output power and thereby limiting...... the voltage ripple. It allows the use of smaller dc link capacitor and hence a longer lifetime and at the same time high power density and low cost can be achieved. The isolated DC/DC converter is controlled to process the desired reactive power in addition to the active power. The control system to achieve...

  11. Analysis of DC control in double-inlet GM type pulse tube refrigerators for detectors

    Science.gov (United States)

    Du, B. Y.

    2016-10-01

    Pulse tube refrigerators have demonstrated many advantages with respect to temperature stability, vibration, reliability and lifetime among cryo-coolers for detectors. Double-inlet type pulse tube refrigerators are popular in GM type pulse tube refrigerators. The single double-inlet valve may introduce DC flow in refrigerator, which deteriorates the performance of pulse tube refrigerator. One new type of DC control mode is introduced in this paper. Two parallel-placed needle valves with opposite direction named double-valve configuration, instead of single double-inlet valve, are used in our experiment to reduce the DC flow. With two double-inlet operating, the lowest cold end temperature of 18.1K and a coolant of 1.2W@20K have been obtained. It has proved that this method is useful for controlling DC flow of the pulse tube refrigerators, which is very important to understand the characters of pulse tube refrigerators for detectors.

  12. Pulsed DC Electric Field-Induced Differentiation of Cortical Neural Precursor Cells.

    Directory of Open Access Journals (Sweden)

    Hui-Fang Chang

    Full Text Available We report the differentiation of neural stem and progenitor cells solely induced by direct current (DC pulses stimulation. Neural stem and progenitor cells in the adult mammalian brain are promising candidates for the development of therapeutic neuroregeneration strategies. The differentiation of neural stem and progenitor cells depends on various in vivo environmental factors, such as nerve growth factor and endogenous EF. In this study, we demonstrated that the morphologic and phenotypic changes of mouse neural stem and progenitor cells (mNPCs could be induced solely by exposure to square-wave DC pulses (magnitude 300 mV/mm at frequency of 100-Hz. The DC pulse stimulation was conducted for 48 h, and the morphologic changes of mNPCs were monitored continuously. The length of primary processes and the amount of branching significantly increased after stimulation by DC pulses for 48 h. After DC pulse treatment, the mNPCs differentiated into neurons, astrocytes, and oligodendrocytes simultaneously in stem cell maintenance medium. Our results suggest that simple DC pulse treatment could control the fate of NPCs. With further studies, DC pulses may be applied to manipulate NPC differentiation and may be used for the development of therapeutic strategies that employ NPCs to treat nervous system disorders.

  13. Pulsed DC Electric Field-Induced Differentiation of Cortical Neural Precursor Cells.

    Science.gov (United States)

    Chang, Hui-Fang; Lee, Ying-Shan; Tang, Tang K; Cheng, Ji-Yen

    2016-01-01

    We report the differentiation of neural stem and progenitor cells solely induced by direct current (DC) pulses stimulation. Neural stem and progenitor cells in the adult mammalian brain are promising candidates for the development of therapeutic neuroregeneration strategies. The differentiation of neural stem and progenitor cells depends on various in vivo environmental factors, such as nerve growth factor and endogenous EF. In this study, we demonstrated that the morphologic and phenotypic changes of mouse neural stem and progenitor cells (mNPCs) could be induced solely by exposure to square-wave DC pulses (magnitude 300 mV/mm at frequency of 100-Hz). The DC pulse stimulation was conducted for 48 h, and the morphologic changes of mNPCs were monitored continuously. The length of primary processes and the amount of branching significantly increased after stimulation by DC pulses for 48 h. After DC pulse treatment, the mNPCs differentiated into neurons, astrocytes, and oligodendrocytes simultaneously in stem cell maintenance medium. Our results suggest that simple DC pulse treatment could control the fate of NPCs. With further studies, DC pulses may be applied to manipulate NPC differentiation and may be used for the development of therapeutic strategies that employ NPCs to treat nervous system disorders.

  14. CrN thin films prepared by reactive DC magnetron sputtering for symmetric supercapacitors

    KAUST Repository

    Wei, Binbin; Liang, Hanfeng; Zhang, Dongfang; Wu, Zhengtao; Qi, Zhengbing; Wang, Zhoucheng

    2016-01-01

    stability are promising candidates as supercapacitor electrode materials. In this work, we report the fabrication of CrN thin films using reactive DC magnetron sputtering and further their applications for symmetric supercapacitors for the first time. The Cr

  15. Interaction of UV laser pulses with reactive dusty plasmas

    NARCIS (Netherlands)

    van de Wetering, F.M.J.H.; Beckers, J.; Nijdam, S.; Oosterbeek, W.; Kovacevic, E.; Berndt, J.

    2016-01-01

    This contribution deals with the effects of UV photons on the synthesis and transport of nanoparticles in reactive complex plasmas (capacitively coupled RF discharge). First measurements showed that the irradiation of a reactive acetylene-argon plasma with high-energy, ns UV laser pulses (355 nm, 75

  16. Electrical Tree Initiation and Growth in Silicone Rubber under Combined DC-Pulse Voltage

    Directory of Open Access Journals (Sweden)

    Tao Han

    2018-03-01

    Full Text Available Electrical tree is a serious threat to silicone rubber (SIR insulation and can even cause breakdown. Electrical trees under alternating current (AC and direct current (DC voltage have been widely researched. While there are pulses in high-voltage direct current (HVDC cables under operating conditions caused by lightning and operating overvoltage in the power system, little research has been reported about trees under combined DC-pulse voltage. Their inception and growth mechanism is still not clear. In this paper, electrical trees are studied under several types of combined DC-pulse voltage. The initiation and growth process was recorded by a digital microscope system. The experimental results indicate that the inception pulse voltage is different under each voltage type and is influenced by the combined DC. The initial tree has two structures, determined by the pulse polarity. With increased DC prestressing time, tree inception pulse voltage with the same polarity is clearly decreased. Moreover, a special initial bubble tree was observed after the prestressing DC.

  17. Preparation of TiN films by arc ion plating using dc and pulsed biases

    International Nuclear Information System (INIS)

    Huang, M.D.; Lee, Y.P.; Dong, C.; Lin, G.Q.; Sun, C.; Wen, L.S.

    2004-01-01

    TiN hard coatings were prepared by arc ion plating with both direct current (dc) and pulsed biases. An extensive investigation was undertaken to determine the effects of the substrate temperature on the mechanical properties and the microstructures of films. The results show that the substrate temperature is decreased evidently when a pulsed bias instead of a dc one is employed. At the same time, the microstructures and the properties are also improved. A low-temperature arc ion plating can be realized by using pulsed biases

  18. Response of larval sea lampreys (Petromyzon marinus) to pulsed DC electrical stimuli in laboratory experiments

    Science.gov (United States)

    Bowen, Anjanette K.; Weisser, John W.; Bergstedt, Roger A.; Famoye, Felix

    2003-01-01

    Four electrical factors that are used in pulsed DC electrofishing for larval sea lampreys (Petromyzon marinus) were evaluated in two laboratory studies to determine the optimal values to induce larval emergence over a range of water temperatures and conductivities. Burrowed larvae were exposed to combinations of pulsed DC electrical factors including five pulse frequencies, three pulse patterns, and two levels of duty cycle over a range of seven voltage gradients in two separate studies conducted at water temperatures of 10, 15, and 20°C and water conductivities of 25, 200, and 900 μS/cm. A four-way analysis of variance was used to determine significant (α = 0.05) influences of each electrical factor on larval emergence. Multiple comparison tests with Bonferroni adjustments were used to determine which values of each factor resulted in significantly higher emergence at each temperature and conductivity. Voltage gradient and pulse frequency significantly affected emergence according to the ANOVA model at each temperature and conductivity tested. Duty cycle and pulse pattern generally did not significantly influence the model. Findings suggest that a setting of 2.0 V/cm, 3 pulses/sec, 10% duty, and 2:2 pulse pattern seems the most promising in waters of medium conductivity and across a variety of temperatures. This information provides a basis for understanding larval response to pulsed DC electrofishing gear factors and identifies electrofisher settings that show promise to increase the efficiency of the gear during assessments for burrowed sea lamprey larvae.

  19. DC drive system for cine/pulse cameras

    Science.gov (United States)

    Gerlach, R. H.; Sharpsteen, J. T.; Solheim, C. D.; Stoap, L. J.

    1977-01-01

    Camera-drive functions are separated mechanically into two groups which are driven by two separate dc brushless motors. First motor, a 90 deg stepper, drives rotating shutter; second electronically commutated motor drives claw and film transport. Shutter is made of one piece but has two openings for slow and fast exposures.

  20. Deposition and characterization of titania-silica optical multilayers by asymmetric bipolar pulsed dc sputtering of oxide targets

    Energy Technology Data Exchange (ETDEWEB)

    Sagdeo, P R; Shinde, D D; Misal, J S [Optics and Thin Film Laboratory, Autonagar, BARC-Vizag, Visakhapatnam -530012 (India); Kamble, N M; Tokas, R B; Biswas, A; Poswal, A K; Thakur, S; Bhattacharyya, D; Sahoo, N K; Sabharwal, S C, E-mail: nksahoo@barc.gov.i, E-mail: sahoonk@gmail.co [Spectroscopy Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India)

    2010-02-03

    Titania-silica (TiO{sub 2}/SiO{sub 2}) optical multilayer structures have been conventionally deposited by reactive sputtering of metallic targets. In order to overcome the problems of arcing, target poisoning and low deposition rates encountered there, the application of oxide targets was investigated in this work with asymmetric bipolar pulsed dc magnetron sputtering. In order to evaluate the usefulness of this deposition methodology, an electric field optimized Fabry Perot mirror for He-Cd laser ({lambda} = 441.6 nm) spectroscopy was deposited and characterized. For comparison, this mirror was also deposited by the reactive electron beam (EB) evaporation technique. The mirrors developed by the two complementary techniques were investigated for their microstructural and optical reflection properties invoking atomic force microscopy, ellipsometry, grazing incidence reflectometry and spectrophotometry. From these measurements the layer geometry, optical constants, mass density, topography, surface and interface roughness and disorder parameters were evaluated. The microstructural properties and spectral functional characteristics of the pulsed dc sputtered multilayer mirror were found to be distinctively superior to the EB deposited mirror. The knowledge gathered during this study has been utilized to develop a 21-layer high-pass edge filter for radio photoluminescence dosimetry.

  1. Deposition and characterization of titania-silica optical multilayers by asymmetric bipolar pulsed dc sputtering of oxide targets

    International Nuclear Information System (INIS)

    Sagdeo, P R; Shinde, D D; Misal, J S; Kamble, N M; Tokas, R B; Biswas, A; Poswal, A K; Thakur, S; Bhattacharyya, D; Sahoo, N K; Sabharwal, S C

    2010-01-01

    Titania-silica (TiO 2 /SiO 2 ) optical multilayer structures have been conventionally deposited by reactive sputtering of metallic targets. In order to overcome the problems of arcing, target poisoning and low deposition rates encountered there, the application of oxide targets was investigated in this work with asymmetric bipolar pulsed dc magnetron sputtering. In order to evaluate the usefulness of this deposition methodology, an electric field optimized Fabry Perot mirror for He-Cd laser (λ = 441.6 nm) spectroscopy was deposited and characterized. For comparison, this mirror was also deposited by the reactive electron beam (EB) evaporation technique. The mirrors developed by the two complementary techniques were investigated for their microstructural and optical reflection properties invoking atomic force microscopy, ellipsometry, grazing incidence reflectometry and spectrophotometry. From these measurements the layer geometry, optical constants, mass density, topography, surface and interface roughness and disorder parameters were evaluated. The microstructural properties and spectral functional characteristics of the pulsed dc sputtered multilayer mirror were found to be distinctively superior to the EB deposited mirror. The knowledge gathered during this study has been utilized to develop a 21-layer high-pass edge filter for radio photoluminescence dosimetry.

  2. Huge increase in gas phase nanoparticle generation by pulsed direct current sputtering in a reactive gas admixture

    Science.gov (United States)

    Polonskyi, Oleksandr; Peter, Tilo; Mohammad Ahadi, Amir; Hinz, Alexander; Strunskus, Thomas; Zaporojtchenko, Vladimir; Biederman, Hynek; Faupel, Franz

    2013-07-01

    Using reactive DC sputtering in a gas aggregation cluster source, we show that pulsed discharge gives rise to a huge increase in deposition rate of nanoparticles by more than one order of magnitude compared to continuous operation. We suggest that this effect is caused by an equilibrium between slight target oxidation (during "time-off") and subsequent sputtering of Ti oxides (sub-oxides) at "time-on" with high power impulse.

  3. Interaction of nanosecond ultraviolet laser pulses with reactive dusty plasma

    International Nuclear Information System (INIS)

    Wetering, F. M. J. H. van de; Oosterbeek, W.; Beckers, J.; Nijdam, S.; Gibert, T.; Mikikian, M.; Rabat, H.; Kovačević, E.; Berndt, J.

    2016-01-01

    Even though UV laser pulses that irradiate a gas discharge are small compared to the plasma volume (≲3%) and plasma-on time (≲6 × 10 −6 %), they are found to dramatically change the discharge characteristics on a global scale. The reactive argon–acetylene plasma allows the growth of nanoparticles with diameters up to 1 μm, which are formed inside the discharge volume due to spontaneous polymerization reactions. It is found that the laser pulses predominantly accelerate and enhance the coagulation phase and are able to suppress the formation of a dust void.

  4. 50 mm Diameter digital DC/pulse neutron generator for subcritical reactor test

    International Nuclear Information System (INIS)

    Li Gang; Zhang Zhongshuai; Chi Qian; Liu Linmao

    2012-01-01

    A 50 mm diameter digital DC/pulse neutron generator was developed with 25 mm ceramic drive-in target neutron tube. It was applied in the subcritical reactor test of China Institute of Atomic Energy (CIAE). The generator can produce neutron in three modes: DC, pulse and multiple pulse. The maximum neutron yield of the generator is 1 × 10 8 n/s, while the maximum pulse frequency is 10 kHz, and the minimum pulse width is 10 μs. As a remote controlled generator, it is small in volume, easy to be connected and controlled. The tested results indicate that penning ion source has the feature of delay time in glow discharge, and it is easier for glow discharge to happen when switching the DC voltage of penning ion source into pulse. According to these two characteristics, the generator has been modified. This improved generator can be used in many other areas including Prompt Gamma Neutron Activation Analysis (PGNAA), neutron testing and experiment.

  5. 50 mm Diameter digital DC/pulse neutron generator for subcritical reactor test

    Energy Technology Data Exchange (ETDEWEB)

    Li Gang; Zhang Zhongshuai [Northeast Normal University, Changchun 130024 (China); Chi Qian [Guang Hua College of Chang Chun University, Changchun 130117 (China); Liu Linmao, E-mail: ll888@nenu.edu.cn [Northeast Normal University, Changchun 130024 (China)

    2012-11-01

    A 50 mm diameter digital DC/pulse neutron generator was developed with 25 mm ceramic drive-in target neutron tube. It was applied in the subcritical reactor test of China Institute of Atomic Energy (CIAE). The generator can produce neutron in three modes: DC, pulse and multiple pulse. The maximum neutron yield of the generator is 1 Multiplication-Sign 10{sup 8} n/s, while the maximum pulse frequency is 10 kHz, and the minimum pulse width is 10 {mu}s. As a remote controlled generator, it is small in volume, easy to be connected and controlled. The tested results indicate that penning ion source has the feature of delay time in glow discharge, and it is easier for glow discharge to happen when switching the DC voltage of penning ion source into pulse. According to these two characteristics, the generator has been modified. This improved generator can be used in many other areas including Prompt Gamma Neutron Activation Analysis (PGNAA), neutron testing and experiment.

  6. Superhydrophobic photocatalytic PTFE – Titania coatings deposited by reactive pDC magnetron sputtering from a blended powder target

    Energy Technology Data Exchange (ETDEWEB)

    Ratova, Marina, E-mail: marina_ratova@hotmail.com; Kelly, Peter J.; West, Glen T.

    2017-04-01

    The production of photocatalytic coatings with superhydrophobic properties, as opposed to the conventional hydrophilic properties, is desirable for the prevention of adhesion of contaminants to photocatalytic surfaces with subsequent deterioration of photocatalytic properties. In this work polytetrafluoroethylene (PTFE) – TiO{sub 2} composite thin films were deposited using a novel method of reactive pulsed direct current (pDC) magnetron sputtering of a blended PTFE – titanium oxide powder target. The surface characteristics and photocatalytic properties of the deposited composite coatings were studied. The as-deposited coatings were annealed at 523 K in air and analysed with Raman spectroscopy, optical profilometry and scanning electron microscopy. Hydrophobicity was assessed though measurements of water contact angles, and photocatalytic properties were studied via methylene blue dye degradation under UV irradiation. It was found that variations of gas flow and, hence, process pressures allowed deposition of samples combining superhydrophobicity with stable photocatalytic efficiency under UV light irradiation. Reversible wettability behaviour was observed with the alternation of light-dark cycles. - Highlights: • PTFE-TiO{sub 2} coatings were deposited by pDC reactive magnetron sputtering. • Blended powder target was used for coatings deposition. • Deposited coatings combined superhydrophobic and photocatalytic properties. • Under UV irradiation coatings exhibited reversible wettability.

  7. Novel high-frequency energy-efficient pulsed-dc generator for capacitively coupled plasma discharge

    Science.gov (United States)

    Mamun, Md Abdullah Al; Furuta, Hiroshi; Hatta, Akimitsu

    2018-03-01

    The circuit design, assembly, and operating tests of a high-frequency and high-voltage (HV) pulsed dc generator (PDG) for capacitively coupled plasma (CCP) discharge inside a vacuum chamber are reported. For capacitive loads, it is challenging to obtain sharp rectangular pulses with fast rising and falling edges, requiring intense current for quick charging and discharging. The requirement of intense current generally limits the pulse operation frequency. In this study, we present a new type of PDG consisting of a pair of half-resonant converters and a constant current-controller circuit connected with HV solid-state power switches that can deliver almost rectangular high voltage pulses with fast rising and falling edges for CCP discharge. A prototype of the PDG is assembled to modulate from a high-voltage direct current (HVdc) input into a pulsed HVdc output, while following an input pulse signal and a set current level. The pulse rise time and fall time are less than 500 ns and 800 ns, respectively, and the minimum pulse width is 1 µs. The maximum voltage for a negative pulse is 1000 V, and the maximum repetition frequency is 500 kHz. During the pulse on time, the plasma discharge current is controlled steadily at the set value. The half-resonant converters in the PDG perform recovery of the remaining energy from the capacitive load at every termination of pulse discharge. The PDG performed with a high energy efficiency of 85% from the HVdc input to the pulsed dc output at a repetition rate of 1 kHz and with stable plasma operation in various discharge conditions. The results suggest that the developed PDG can be considered to be more efficient for plasma processing by CCP.

  8. Novel high-frequency energy-efficient pulsed-dc generator for capacitively coupled plasma discharge.

    Science.gov (United States)

    Mamun, Md Abdullah Al; Furuta, Hiroshi; Hatta, Akimitsu

    2018-03-01

    The circuit design, assembly, and operating tests of a high-frequency and high-voltage (HV) pulsed dc generator (PDG) for capacitively coupled plasma (CCP) discharge inside a vacuum chamber are reported. For capacitive loads, it is challenging to obtain sharp rectangular pulses with fast rising and falling edges, requiring intense current for quick charging and discharging. The requirement of intense current generally limits the pulse operation frequency. In this study, we present a new type of PDG consisting of a pair of half-resonant converters and a constant current-controller circuit connected with HV solid-state power switches that can deliver almost rectangular high voltage pulses with fast rising and falling edges for CCP discharge. A prototype of the PDG is assembled to modulate from a high-voltage direct current (HVdc) input into a pulsed HVdc output, while following an input pulse signal and a set current level. The pulse rise time and fall time are less than 500 ns and 800 ns, respectively, and the minimum pulse width is 1 µs. The maximum voltage for a negative pulse is 1000 V, and the maximum repetition frequency is 500 kHz. During the pulse on time, the plasma discharge current is controlled steadily at the set value. The half-resonant converters in the PDG perform recovery of the remaining energy from the capacitive load at every termination of pulse discharge. The PDG performed with a high energy efficiency of 85% from the HVdc input to the pulsed dc output at a repetition rate of 1 kHz and with stable plasma operation in various discharge conditions. The results suggest that the developed PDG can be considered to be more efficient for plasma processing by CCP.

  9. Effect of dc and pulsed corona discharge on DNA and proteins

    International Nuclear Information System (INIS)

    Shvedchikov, A.P.; Polyakova, A.V.; Belousova, E.V.; Ponizovskii, A.Z.; Goncharov, V.A.

    1993-01-01

    The authors have investigated the effect of a d.c. and pulsed corona discharge in air and nitrogen on DNA and albumin films in the temperature range 77-298 K. The authors have shown that upon exposure to a corona discharge and O 3 , the biopolymers are degraded. With a reduction in temperature, the extent of degradation of DNA drops

  10. Experimental investigation of plasma dynamics in dc and short-pulse magnetron discharges

    International Nuclear Information System (INIS)

    Seo, Sang-Hun; In, Jung-Hwan; Chang, Hong-Young

    2006-01-01

    The spatiotemporal evolution of the electron energy distribution function (EEDF) and of plasma parameters such as the electron density, the electron temperature and the plasma and floating potentials has been investigated using spatially and temporally resolved single Langmuir probe measurements in dc and mid-frequency, short-pulse magnetron discharges with a repetition frequency of 10 kHz and a duty cycle of 10%. In the pulsed discharge of the short duty cycle, a peak electron temperature higher than 10 eV was observed near the cathode fall region during the early phase of the pulse-on, which is about three times higher than the steady-state value of the electron temperature in the dc discharge. The temporal evolution of the measured EEDFs showed the initial efficient electron heating during the early phase of the pulse-on and the subsequent relaxation of electron energy by the inelastic collisions and the diffusive loss. The high-energy electrons generated during the pulse-on phase diffused the downstream region toward the grounded substrate, resulting in a bi-Maxwellian EEDF consisting of the background low-energy electrons and the high-energy electrons. The results of the spatially and temporally resolved probe measurements will be presented and the enhanced efficiency of the electron heating in the short-pulse discharge will be explained on the basis of the global model of a pulsed discharge

  11. Comparative study of nanocomposites prepared by pulsed and dc sputtering combined with plasma polymerization suitable for photovoltaic device applications

    Energy Technology Data Exchange (ETDEWEB)

    Hussain, Amreen A. [Physical Sciences Division, Institute of Advanced Study in Science and Technology, Guwahati, Assam (India); Pal, Arup R., E-mail: arpal@iasst.gov.in [Physical Sciences Division, Institute of Advanced Study in Science and Technology, Guwahati, Assam (India); Kar, Rajib [Laser and Plasma Technology Division, Bhabha Atomic Research Center, Trombay, Mumbai (India); Bailung, Heremba; Chutia, Joyanti [Physical Sciences Division, Institute of Advanced Study in Science and Technology, Guwahati, Assam (India); Patil, Dinkar S. [Laser and Plasma Technology Division, Bhabha Atomic Research Center, Trombay, Mumbai (India)

    2014-12-15

    Plasma processing, a single step method for production of large area composite films, is employed to deposit plasma polymerized aniline-Titanium dioxide (PPani-TiO{sub 2}) nanocomposite thin films. The deposition of PPani-TiO{sub 2} nanocomposite films are made using reactive magnetron sputtering and plasma polymerization combined process. This study focuses on the direct comparison between continuous and pulsed dc magnetron sputtering techniques of titanium in combination with rf plasma polymerization of aniline. The deposited PPani-TiO{sub 2} nanocomposite films are characterized and discussed in terms of structural, morphological and optical properties. A self powered hybrid photodetector has been developed by plasma based process. The proposed method provides a new route where the self-assembly of molecules, that is, the spontaneous association of atomic or molecular building blocks under plasma environment, emerge as a successful strategy to form well-defined structural and morphological units of nanometer dimensions. - Highlights: • PPani-TiO{sub 2} nanocomposite by pulsed and dc sputtering with rf plasma polymerization. • In-situ and Ex-situ H{sub 2}SO{sub 4} doping in PPani-TiO{sub 2} nanocomposite. • PPani-TiO{sub 2} nanocomposite based self-powered-hybrid photodetector.

  12. Comparative study of nanocomposites prepared by pulsed and dc sputtering combined with plasma polymerization suitable for photovoltaic device applications

    International Nuclear Information System (INIS)

    Hussain, Amreen A.; Pal, Arup R.; Kar, Rajib; Bailung, Heremba; Chutia, Joyanti; Patil, Dinkar S.

    2014-01-01

    Plasma processing, a single step method for production of large area composite films, is employed to deposit plasma polymerized aniline-Titanium dioxide (PPani-TiO 2 ) nanocomposite thin films. The deposition of PPani-TiO 2 nanocomposite films are made using reactive magnetron sputtering and plasma polymerization combined process. This study focuses on the direct comparison between continuous and pulsed dc magnetron sputtering techniques of titanium in combination with rf plasma polymerization of aniline. The deposited PPani-TiO 2 nanocomposite films are characterized and discussed in terms of structural, morphological and optical properties. A self powered hybrid photodetector has been developed by plasma based process. The proposed method provides a new route where the self-assembly of molecules, that is, the spontaneous association of atomic or molecular building blocks under plasma environment, emerge as a successful strategy to form well-defined structural and morphological units of nanometer dimensions. - Highlights: • PPani-TiO 2 nanocomposite by pulsed and dc sputtering with rf plasma polymerization. • In-situ and Ex-situ H 2 SO 4 doping in PPani-TiO 2 nanocomposite. • PPani-TiO 2 nanocomposite based self-powered-hybrid photodetector

  13. Numerical simulation of Trichel pulses of negative DC corona discharge based on a plasma chemical model

    Science.gov (United States)

    Chen, Xiaoyue; Lan, Lei; Lu, Hailiang; Wang, Yu; Wen, Xishan; Du, Xinyu; He, Wangling

    2017-10-01

    A numerical simulation method of negative direct current (DC) corona discharge based on a plasma chemical model is presented, and a coaxial cylindrical gap is adopted. There were 15 particle species and 61 kinds of collision reactions electrons involved, and 22 kinds of reactions between ions are considered in plasma chemical reactions. Based on this method, continuous Trichel pulses are calculated on about a 100 us timescale, and microcosmic physicochemical process of negative DC corona discharge in three different periods is discussed. The obtained results show that the amplitude of Trichel pulses is between 1-2 mA, and that pulse interval is in the order of 10-5 s. The positive ions produced by avalanche ionization enhanced the electric field near the cathode at the beginning of the pulse, then disappeared from the surface of cathode. The electric field decreases and the pulse ceases to develop. The negative ions produced by attachment slowly move away from the cathode, and the electric field increases gradually until the next pulse begins to develop. The positive and negative ions with the highest density during the corona discharge process are O4+ and O3- , respectively.

  14. Pulsed neutron method for diffusion, slowing down, and reactivity measurements

    International Nuclear Information System (INIS)

    Sjoestrand, N.G.

    1985-01-01

    An outline is given on the principles of the pulsed neutron method for the determination of thermal neutron diffusion parameters, for slowing-down time measurements, and for reactivity determinations. The historical development is sketched from the breakthrough in the middle of the nineteen fifties and the usefulness and limitations of the method are discussed. The importance for the present understanding of neutron slowing-down, thermalization and diffusion are point out. Examples are given of its recent use for e.g. absorption cross section measurements and for the study of the properties of heterogeneous systems

  15. A study of the plasma electronegativity in an argon-oxygen pulsed-dc sputter magnetron

    International Nuclear Information System (INIS)

    You, S D; Dodd, R; Edwards, A; Bradley, J W

    2010-01-01

    Using Langmuir probe-assisted laser photodetachment, the temporal evolution of the O - density was determined in the bulk plasma of a unipolar pulsed-dc magnetron. The source was operated in reactive mode, at a fixed nominal on-time power of 100 W, sputtering Ti in argon-oxygen atmospheres at 1.3 Pa pressure, but over a variation of duty cycles from 5% to 50% and oxygen partial pressures of 10% and 50% of the total pressure. In the plasma on-time, for all duty cycles the negative ion density (n - ) rises marginally reaching values typically less than 2 x 10 15 m -3 with negative ion-to-electron density ratios, α - falls by about 20-30% as fast O - species created at the cathode exit the system. This is followed by a rapid rise in n - to values at least 2 or 3 times that in the on-time. The rate of rise of n - and its maximum value both increase with decreasing duty cycle. In the off-time, the electron density falls rapidly (initial decay rates of several tens of μs), and therefore the afterglow plasma becomes highly electronegative, with α reaching 4.6 and 14.4 for 10% and 50% oxygen partial pressure, respectively. The rapid rise in n - in the afterglow (in which the electron temperature falls from about 5 to 0.5 eV) is attributed to the dissociative attachment of highly excited oxygen metastables, which themselves are created in the pulse on-time. At the lowest duty of 5%, the long-term O - decay times are several hundred μs. Langmuir probe characteristics show the clear signature that negative ions dominate over the electrons in the off-time. From the ion and electron saturation current ratios, α has been estimated in some chosen cases and found to agree within a factor between 2 and 10 with those obtained more directly from the photodetachment method.

  16. Ion energy distributions in bipolar pulsed-dc discharges of methane measured at the biased cathode

    Energy Technology Data Exchange (ETDEWEB)

    Corbella, C; Rubio-Roy, M; Bertran, E; Portal, S; Pascual, E; Polo, M C; Andujar, J L, E-mail: corbella@ub.edu [FEMAN Group, IN2UB, Departament de Fisica Aplicada i Optica, Universitat de Barcelona, c/ MartI i Franques 1, 08028 Barcelona (Spain)

    2011-02-15

    The ion fluxes and ion energy distributions (IED) corresponding to discharges in methane (CH{sub 4}) were measured in time-averaged mode with a compact retarding field energy analyser (RFEA). The RFEA was placed on a biased electrode at room temperature, which was powered by either radiofrequency (13.56 MHz) or asymmetric bipolar pulsed-dc (250 kHz) signals. The shape of the resulting IED showed the relevant populations of ions bombarding the cathode at discharge parameters typical in the material processing technology: working pressures ranging from 1 to 10 Pa and cathode bias voltages between 100 and 200 V. High-energy peaks in the IED were detected at low pressures, whereas low-energy populations became progressively dominant at higher pressures. This effect is attributed to the transition from collisionless to collisional regimes of the cathode sheath as the pressure increases. On the other hand, pulsed-dc plasmas showed broader IED than RF discharges. This fact is connected to the different working frequencies and the intense peak voltages (up to 450 V) driven by the pulsed power supply. This work improves our understanding in plasma processes at the cathode level, which are of crucial importance for the growth and processing of materials requiring controlled ion bombardment. Examples of industrial applications with these requirements are plasma cleaning, ion etching processes during fabrication of microelectronic devices and plasma-enhanced chemical vapour deposition of hard coatings (diamond-like carbon, carbides and nitrides).

  17. Power quality improvement by using multi-pulse AC-DC converters for DC drives: Modeling, simulation and its digital implementation

    Directory of Open Access Journals (Sweden)

    Mohd Tariq

    2014-12-01

    Full Text Available The paper presents the modeling, simulation and digital implementation of power quality improvement of DC drives by using multi pulse AC–DC converter. As it is a well-known fact that power quality determines the fitness of electrical power to consumer devices, hence an effort has been made to improve power quality in this work. Simulation and digital implementation with the help of MATLAB/Simulink has been done and results obtained are discussed in detail to verify the theoretical results. The multipulse converter was connected with DC drives and was run at no load condition to find out the transient and steady state performances. FFT analysis has been performed and Total Harmonic Distortion (THD results obtained at different pulses are shown here.

  18. Methods and Apparatus for Pulsed-DC Dielectric Barrier Discharge Plasma Actuator and Circuit

    Science.gov (United States)

    Corke, Thomas C. (Inventor); Kaszeta, Richard (Inventor); Gold, Calman (Inventor)

    2017-01-01

    A plasma generating device intended to induce a flow in a fluid via plasma generation includes a dielectric separating two electrodes and a power supply. The first electrode is exposed to a fluid flow while the second electrode is positioned under the dielectric. The power supply is electrically coupled to a switch and the first and second electrodes. When the power supply is energized by repeated action of the switch, it causes a pulsed DC current between the electrodes which causes the fluid to ionize generating a plasma. The generation of the plasma induces a force with a velocity component in the fluid.

  19. Synchronized Pulsed dc - dc Converter as Maximum Power Position Tracker with Wide Load and Insolation Variation for Stand Alone PV System

    International Nuclear Information System (INIS)

    Hardik, P. Desai; Ranjan Maheshwari

    2011-01-01

    This paper investigates the interest focused on employing parallel connected dc-dc converter with high tracking effectiveness under wide variation in environmental conditions (Insolation) and wide load variation. dc-dc converter is an essential part of the stand alone PV system. Paper also presents an approach on how duty cycle for maximum power position (MPP) is adjusted by taking care of varying load conditions and without iterative steps. Synchronized PWM pulses are employed for the converter. High tracking efficiency is achieved with continuous input and inductor current. In this approach, the converter can he utilized in buck as well in boost mode. The PV system simulation was verified and experimental results were in agreement to the presented scheme. (authors)

  20. Dielectric properties of DC reactive magnetron sputtered Al2O3 thin films

    International Nuclear Information System (INIS)

    Prasanna, S.; Mohan Rao, G.; Jayakumar, S.; Kannan, M.D.; Ganesan, V.

    2012-01-01

    Alumina (Al 2 O 3 ) thin films were sputter deposited over well-cleaned glass and Si substrates by DC reactive magnetron sputtering under various oxygen gas pressures and sputtering powers. The composition of the films was analyzed by X-ray photoelectron spectroscopy and an optimal O/Al atomic ratio of 1.59 was obtained at a reactive gas pressure of 0.03 Pa and sputtering power of 70 W. X-ray diffraction results revealed that the films were amorphous until 550 °C. The surface morphology of the films was studied using scanning electron microscopy and the as-deposited films were found to be smooth. The topography of the as-deposited and annealed films was analyzed by atomic force microscopy and a progressive increase in the rms roughness of the films from 3.2 nm to 4.53 nm was also observed with increase in the annealing temperature. Al-Al 2 O 3 -Al thin film capacitors were then fabricated on glass substrates to study the effect of temperature and frequency on the dielectric property of the films. Temperature coefficient of capacitance, AC conductivity and activation energy were determined and the results are discussed. - Highlights: ► Al 2 O 3 thin films were deposited by DC reactive magnetron sputtering. ► The films were found to be amorphous up to annealing temperature of 550 C. ► An increase in rms roughness of the films was observed with annealing. ► Al-Al 2 O 3 -Al thin film capacitors were fabricated and dielectric constant was 7.5. ► The activation energy decreased with increase in frequency.

  1. Bioactivity response of Ta_1_-_xO_x coatings deposited by reactive DC magnetron sputtering

    International Nuclear Information System (INIS)

    Almeida Alves, C.F.; Cavaleiro, A.; Carvalho, S.

    2016-01-01

    The use of dental implants is sometimes accompanied by failure due to periimplantitis disease and subsequently poor esthetics when soft–hard tissue margin recedes. As a consequence, further research is needed for developing new bioactive surfaces able to enhance the osseous growth. Tantalum (Ta) is a promising material for dental implants since, comparing with titanium (Ti), it is bioactive and has an interesting chemistry which promotes the osseointegration. Another promising approach for implantology is the development of implants with oxidized surfaces since bone progenitor cells interact with the oxide layer forming a diffusion zone due to its ability to bind with calcium which promotes a stronger bond. In the present report Ta-based coatings were deposited by reactive DC magnetron sputtering onto Ti CP substrates in an Ar + O_2 atmosphere. In order to assess the osteoconductive response of the studied materials, contact angle and in vitro tests of the samples immersed in Simulated Body Fluid (SBF) were performed. Structural results showed that oxide phases where achieved with larger amounts of oxygen (70 at.% O). More compact and smooth coatings were deposited by increasing the oxygen content. The as-deposited Ta coating presented the most hydrophobic character (100°); with increasing oxygen amount contact angles progressively diminished, down to the lowest measured value, 63°. The higher wettability is also accompanied by an increase on the surface energy. Bioactivity tests demonstrated that highest O-content coating, in good agreement with wettability and surface energy values, showed an increased affinity for apatite adhesion, with higher Ca/P ratio formation, when compared to the bare Ti substrates. - Highlights: • Ta_1_-_xO_x coatings were deposited by reactive DC magnetron sputtering. • Amorphous oxide phases were achieved with higher oxygen amounts. • Contact angles progressively diminished, with increasing oxygen content. • Ta oxide surface

  2. Active screen cage pulsed dc discharge for implanting copper in polytetrafluoroethylene (PTFE)

    Science.gov (United States)

    Zaka-ul-Islam, Mujahid; Naeem, Muhammad; Shafiq, Muhammad; Sitara; Jabbar Al-Rajab, Abdul; Zakaullah, Muhammad

    2017-07-01

    Polymers such as polytetrafluoroethylene (PTFE) are widely used in artificial organs where long-term anti-bacterial properties are required to avoid bacterial proliferation. Copper or silver ion implantation on the polymer surface is known as a viable method to generate long-term anti-bacterial properties. Here, we have tested pulsed DC plasma with copper cathodic cage for the PTFE surface treatment. The surface analysis of the treated specimens suggests that the surface, structural properties, crystallinity and chemical structure of the PTFE have been changed, after the plasma treatment. The copper release tests show that copper ions are released from the polymer at a slow rate and quantity of the released copper increases with the plasma treatment time.

  3. Tracing the plasma interactions for pulsed reactive crossed-beam laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jikun; Stender, Dieter; Pichler, Markus; Pergolesi, Daniele; Schneider, Christof W.; Wokaun, Alexander; Lippert, Thomas, E-mail: thomas.lippert@psi.ch [General Energy Research Department, Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland); Döbeli, Max [Ion Beam Physics, ETH Zurich, CH-8093 Zurich (Switzerland)

    2015-10-28

    Pulsed reactive crossed-beam laser ablation is an effective technique to govern the chemical activity of plasma species and background molecules during pulsed laser deposition. Instead of using a constant background pressure, a gas pulse with a reactive gas, synchronized with the laser beam, is injected into vacuum or a low background pressure near the ablated area of the target. It intercepts the initially generated plasma plume, thereby enhancing the physicochemical interactions between the gaseous environment and the plasma species. For this study, kinetic energy resolved mass-spectrometry and time-resolved plasma imaging were used to study the physicochemical processes occurring during the reactive crossed beam laser ablation of a partially {sup 18}O substituted La{sub 0.6}Sr{sub 0.4}MnO{sub 3} target using oxygen as gas pulse. The characteristics of the ablated plasma are compared with those observed during pulsed laser deposition in different oxygen background pressures.

  4. Tracing the plasma interactions for pulsed reactive crossed-beam laser ablation

    Science.gov (United States)

    Chen, Jikun; Stender, Dieter; Pichler, Markus; Döbeli, Max; Pergolesi, Daniele; Schneider, Christof W.; Wokaun, Alexander; Lippert, Thomas

    2015-10-01

    Pulsed reactive crossed-beam laser ablation is an effective technique to govern the chemical activity of plasma species and background molecules during pulsed laser deposition. Instead of using a constant background pressure, a gas pulse with a reactive gas, synchronized with the laser beam, is injected into vacuum or a low background pressure near the ablated area of the target. It intercepts the initially generated plasma plume, thereby enhancing the physicochemical interactions between the gaseous environment and the plasma species. For this study, kinetic energy resolved mass-spectrometry and time-resolved plasma imaging were used to study the physicochemical processes occurring during the reactive crossed beam laser ablation of a partially 18O substituted La0.6Sr0.4MnO3 target using oxygen as gas pulse. The characteristics of the ablated plasma are compared with those observed during pulsed laser deposition in different oxygen background pressures.

  5. Time-resolved study of a pulsed dc discharge using quantum cascade laser absorption spectroscopy : NO and gas temperature kinetics

    NARCIS (Netherlands)

    Welzel, S.; Gatilova, L.; Röpcke, J.; Rousseau, A.

    2007-01-01

    In a pulsed dc discharge of an Ar–N2 mixture containing 0.91% of NO the kinetics of the destruction of NO has been studied under static and flowing conditions, i.e. in a closed and open discharge tube (p = 266 Pa). For this purpose quantum cascade laser absorption spectroscopy (QCLAS) in the

  6. A 34 MW, 120 MJ pulsed dc supply for the UK tokamak reactor ''DITE''

    International Nuclear Information System (INIS)

    Fry, M.G.J.

    1978-01-01

    A static rectifier set supplying as much as 120 MJ of energy at a peak power of 34 MW to the toroidal magnet coils in the DITE experiment is described in detail. The power supply is designed to meet the stringent requirements concerning the maximum admissible peak reactive power. The rectifier is divided into two series-connected sections, one with diode bridges providing a fixed voltage, the other with thyristors which may work in either the rectifier or line-commutated inverter mode. The rectifier transformers are preceded by mechanical line-voltage regulators of the patented ''Interstep'' types, which comprise dual-voltage 11/33 kV tapped autotransformers and tap selection switches. Four parallel-connected thyristor bridges are used, perfect current sharing being assured by independent control of firing circuits. The firing circuits consist of non-conventional pulse generators and pulse amplifiers. Trains of precisely timed firing pulses are produced by using the phase-lock loop technique and the TTL logic. An extremely high noise immunity is achieved. (J.U.)

  7. CrN thin films prepared by reactive DC magnetron sputtering for symmetric supercapacitors

    KAUST Repository

    Wei, Binbin

    2016-12-29

    Supercapacitors have been becoming indispensable energy storage devices in micro-electromechanical systems and have been widely studied over the past few decades. Transition metal nitrides with excellent electrical conductivity and superior cycling stability are promising candidates as supercapacitor electrode materials. In this work, we report the fabrication of CrN thin films using reactive DC magnetron sputtering and further their applications for symmetric supercapacitors for the first time. The CrN thin film electrodes fabricated under the deposition pressure of 3.5 Pa show an areal specific capacitance of 12.8 mF cm at 1.0 mA cm and high cycling stability with 92.1% capacitance retention after 20 000 cycles in a 0.5 M HSO electrolyte. Furthermore, our developed CrN//CrN symmetric supercapacitor can deliver a high energy density of 8.2 mW h cm at the power density of 0.7 W cm along with outstanding cycling stability. Thus, the CrN thin films have great potential for application in supercapacitors and other energy storage systems.

  8. Electrical and optical properties of reactive DC magnetron sputtered silver oxide thin films: role of oxygen

    Energy Technology Data Exchange (ETDEWEB)

    Kumar Barik, Ullash; Srinivasan, S; Nagendra, C L; Subrahmanyam, A

    2003-04-01

    Silver oxide thin films have been prepared on soda lime glass substrates at room temperature (300 K) by reactive DC Magnetron sputtering technique using pure silver metal target; the oxygen flow rates have been varied in the range 0.00-2.01 sccm. The X-ray diffraction data on these films show a systematic change from metallic silver to silver (sub) oxides. The electrical resistivity increases with increasing oxygen flow. The films show a p-type behavior (by both Hall and Seebeck measurements) for the oxygen flow rates of 0.54, 1.09 and 1.43 sccm. The refractive index of the films (at 632.8 nm) decreases with increasing oxygen content and is in the range 1.167-1.145, whereas the p-type films show a higher refractive index (1.186-1.204). The work function of these silver oxide films has been measured by Kelvin Probe technique. The results, in specific, the p-type conductivity in the silver oxide films, have been explained on the basis of the theory of partial ionic charge proposed by Sanderson.

  9. Electrical and optical properties of reactive DC magnetron sputtered silver oxide thin films: role of oxygen

    International Nuclear Information System (INIS)

    Kumar Barik, Ullash; Srinivasan, S.; Nagendra, C.L.; Subrahmanyam, A.

    2003-01-01

    Silver oxide thin films have been prepared on soda lime glass substrates at room temperature (300 K) by reactive DC Magnetron sputtering technique using pure silver metal target; the oxygen flow rates have been varied in the range 0.00-2.01 sccm. The X-ray diffraction data on these films show a systematic change from metallic silver to silver (sub) oxides. The electrical resistivity increases with increasing oxygen flow. The films show a p-type behavior (by both Hall and Seebeck measurements) for the oxygen flow rates of 0.54, 1.09 and 1.43 sccm. The refractive index of the films (at 632.8 nm) decreases with increasing oxygen content and is in the range 1.167-1.145, whereas the p-type films show a higher refractive index (1.186-1.204). The work function of these silver oxide films has been measured by Kelvin Probe technique. The results, in specific, the p-type conductivity in the silver oxide films, have been explained on the basis of the theory of partial ionic charge proposed by Sanderson

  10. Structural and optical properties of DC reactive magnetron sputtered zinc aluminum oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, B. Rajesh, E-mail: rajphyind@gmail.com [Department of Physics, GITAM Institute of Technology, GITAM University, Visakhapatnam - 530 045, A.P. (India); Rao, T. Subba, E-mail: thotasubbarao6@gmail.com [Department of Physics, Sri Krishnadevaraya University, Anantapuramu - 515 003, A.P. (India)

    2014-10-15

    Highly transparent conductive Zinc Aluminum Oxide (ZAO) thin films have been deposited on glass substrates using DC reactive magnetron sputtering method. The thin films were deposited at 200 °C and post-deposition annealing from 15 to 90 min. XRD patterns of ZAO films exhibit only (0 0 2) diffraction peak, indicating that they have c-axis preferred orientation perpendicular to the substrate. Scanning electron microscopy (SEM) is used to study the surface morphology of the films. The grain size obtained from SEM images of ZAO thin films are found to be in the range of 20 - 26 nm. The minimum resistivity of 1.74 × 10{sup −4} Ω cm and an average transmittance of 92% are obtained for the thin film post annealed for 30 min. The optical band gap of ZAO thin films increased from 3.49 to 3.60 eV with the increase of annealing time due to Burstein-Moss effect. The optical constants refractive index (n) and extinction coefficient (k) were also determined from the optical transmission spectra.

  11. A study of the transient plasma potential in a pulsed bi-polar dc magnetron discharge

    International Nuclear Information System (INIS)

    Bradley, J W; Karkari, S K; Vetushka, A

    2004-01-01

    The temporal evolution of the plasma potential, V p , in a pulsed dc magnetron plasma has been determined using the emissive probe technique. The discharge was operated in the 'asymmetric bi-polar' mode, in which the discharge voltage changes polarity during part of the pulse cycle. The probe measurements, with a time-resolution of 20 ns or better, were made along a line above the racetrack, normal to the plane of the cathode target, for a fixed frequency (100 kHz), duty cycle (50%), argon pressure (0.74 Pa) and discharge power (583 W). At all the measured positions, V p was found to respond to the large and rapid changes in the cathode voltage, V d , during the different phases of the pulse cycle, with V p always more positive than V d . At a typical substrate position (>80 mm from the target), V p remains a few volts above the most positive surface in the discharge at all times. In the 'on' phase of the pulse, the measurements show a significant axial electric field is generated in the plasma, with the plasma potential dropping by a total of about 30 V over a distance of 70 mm, from the bulk plasma to a position close to the beginning of the cathode fall. This is consistent with measurements made in the dc magnetron. During the stable 'reverse' phase of the discharge, for distances greater than 18 mm from the target, the axial electric field is found to collapse, with V p elevated uniformly to about 3 V above V d . Between the target and this field-free region an ion sheath forms, and the current flowing to the target is still an ion current in this 'reverse' period. During the initial 200 ns of the voltage 'overshoot' phase (between 'on' and 'reverse' phases), V d reached a potential of +290 V; however, close to the target, V p was found to attain a much higher value, namely +378 V. Along the line of measurement, the axial electric field reverses in direction in this phase, and an electron current of up to 9 A flows to the target. The spatial and temporal

  12. Study of sterilization-treatment in pure and N- doped carbon thin films synthesized by inductively coupled plasma assisted pulsed-DC magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Javid, Amjed [Center for Advanced Plasma Surface Technology (CAPST), NU-SKKU Joint Institute for Plasma Nano-Materials (IPNM), Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Department of Textile Processing, National Textile University, Faisalabad 37610 (Pakistan); Kumar, Manish, E-mail: manishk@skku.edu [Center for Advanced Plasma Surface Technology (CAPST), NU-SKKU Joint Institute for Plasma Nano-Materials (IPNM), Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Han, Jeon Geon, E-mail: hanjg@skku.edu [Center for Advanced Plasma Surface Technology (CAPST), NU-SKKU Joint Institute for Plasma Nano-Materials (IPNM), Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2017-01-15

    Highlights: • Pure and N-doped nanocrystallie carbon films are synthesized by ICP assisted pulsed DC plasma process. • ICP power induces the increase in average graphitic crystallite size from 4.86 nm to 6.42 nm. • Beneficial role of ICP source assistance to achieve high sputtering throughput (deposition rate ∼55 nm/min). • Post-sterilization electron-transport study shows N-doped carbon films having promising stability. - Abstract: Electrically-conductive nanocrystalline carbon films, having non-toxic and non-immunogenic characteristics, are promising candidates for reusable medical devices. Here, the pure and N- doped nanocrystalline carbon films are deposited by the assistance of inductively coupled plasma (ICP) in an unbalanced facing target pulsed-DC magnetron sputtering process. Through the optical emission spectroscopy study, the role of ICP assistance and N-doping on the reactive components/radicals during the synthesis is presented. The N-doping enhances the three fold bonding configurations by increasing the ionization and energies of the plasma species. Whereas, the ICP addition increases the plasma density to control the deposition rate and film structure. As a result, sputtering-throughput (deposition rate: 31–55 nm/min), electrical resistivity (4–72 Ωcm) and water contact angle (45.12°–54°) are significantly tailored. Electric transport study across the surface microchannel confirms the superiority of N-doped carbon films for sterilization stability over the undoped carbon films.

  13. Optimization of pulsed DC PACVD parameters: Toward reducing wear rate of the DLC films

    International Nuclear Information System (INIS)

    Ebrahimi, Mansoureh; Mahboubi, Farzad; Naimi-Jamal, M. Reza

    2016-01-01

    Highlights: • Effect of pulsed DC PACVD deposition temperature, duty cycle, hydrogen flow and argon/CH4 flow ratio on the wear rate and durability of DLC films was studied. • Results show that wear rate of the DLC films, reduced from 14×E-4 mm3/Nm to 1×E-6 mm3/Nm with increasing the duty cycle from 50% to 80%. • In low duty cycle (around 50%), wear rate increases with increasing in Argon/CH4 flow ratio. • Oxidation, fatigue, abrasion and graphitization are main wear mechanisms in the DLC film. - Abstract: The effect of pulsed direct current (DC) plasma-assisted chemical vapor deposition (PACVD) parameters such as temperature, duty cycle, hydrogen flow, and argon/CH_4 flow ratio on the wear behavior and wear durability of the diamond-like carbon (DLC) films was studied by using response surface methodology (RSM). DLC films were deposited on nitrocarburized AISI 4140 steel. Wear rate and wear durability of the DLC films were examined with the pin-on-disk method. Field emission scanning electron microscopy, Raman spectroscopy, and nanoindentation techniques were used for studying wear mechanisms, chemical structure, and hardness of the DLC films. RSM results show that duty cycle is one of the important parameters that affect the wear rate of the DLC samples. The wear rate of the samples deposited with a duty cycle of >75% decreases with an increase in the argon/CH4 ratio. In contrast, for a duty cycle of <65%, the wear rate increases with an increase in the argon/CH_4 ratio. The wear durability of the DLC samples increases with an increase in the duty cycle, hydrogen flow, and argon/CH_4 flow ratio at the deposition temperature between 85 °C and 110 °C. Oxidation, fatigue, abrasive wear, and graphitization are the wear mechanisms observed on the wear scar of the DLC samples deposited with the optimum deposition conditions.

  14. Optimization of pulsed DC PACVD parameters: Toward reducing wear rate of the DLC films

    Energy Technology Data Exchange (ETDEWEB)

    Ebrahimi, Mansoureh [Department of Mining and Metallurgical Engineering, Amirkabir University of Technology, P.O. Box 1875-4413, Tehran (Iran, Islamic Republic of); Mahboubi, Farzad, E-mail: mahboubi@aut.ac.ir [Department of Mining and Metallurgical Engineering, Amirkabir University of Technology, P.O. Box 1875-4413, Tehran (Iran, Islamic Republic of); Naimi-Jamal, M. Reza [Research Laboratory of Green Organic Synthesis and Polymers, Department of Chemistry, Iran University of Science and Technology, P.O. Box 16846, Tehran (Iran, Islamic Republic of)

    2016-12-15

    Highlights: • Effect of pulsed DC PACVD deposition temperature, duty cycle, hydrogen flow and argon/CH4 flow ratio on the wear rate and durability of DLC films was studied. • Results show that wear rate of the DLC films, reduced from 14×E-4 mm3/Nm to 1×E-6 mm3/Nm with increasing the duty cycle from 50% to 80%. • In low duty cycle (around 50%), wear rate increases with increasing in Argon/CH4 flow ratio. • Oxidation, fatigue, abrasion and graphitization are main wear mechanisms in the DLC film. - Abstract: The effect of pulsed direct current (DC) plasma-assisted chemical vapor deposition (PACVD) parameters such as temperature, duty cycle, hydrogen flow, and argon/CH{sub 4} flow ratio on the wear behavior and wear durability of the diamond-like carbon (DLC) films was studied by using response surface methodology (RSM). DLC films were deposited on nitrocarburized AISI 4140 steel. Wear rate and wear durability of the DLC films were examined with the pin-on-disk method. Field emission scanning electron microscopy, Raman spectroscopy, and nanoindentation techniques were used for studying wear mechanisms, chemical structure, and hardness of the DLC films. RSM results show that duty cycle is one of the important parameters that affect the wear rate of the DLC samples. The wear rate of the samples deposited with a duty cycle of >75% decreases with an increase in the argon/CH4 ratio. In contrast, for a duty cycle of <65%, the wear rate increases with an increase in the argon/CH{sub 4} ratio. The wear durability of the DLC samples increases with an increase in the duty cycle, hydrogen flow, and argon/CH{sub 4} flow ratio at the deposition temperature between 85 °C and 110 °C. Oxidation, fatigue, abrasive wear, and graphitization are the wear mechanisms observed on the wear scar of the DLC samples deposited with the optimum deposition conditions.

  15. Tribological behavior of an austenitic stainless steel AISI 316L nitrurated by DC-pulsed plasma

    International Nuclear Information System (INIS)

    De Las Heras, E; Walther, F; Corengia, P.A; Quinteiro, M.O; Cabo, A; Bruhl, S; Sommadossi, S

    2004-01-01

    Austenitic stainless steels are widely used in different applications because they withstands corrosion. Ionic nitruration has proven to be an adequate technique for modifying this type of steel, in order to improve its resistance to wear without diminishing its resistance to corrosion. While many publications have reported improvements in the tribological properties of the nitrurated AISI 316, systematic studies that evaluate this behavior using industrial equipment for its thermochemical treatment are of interest. This work studied the tribological behavior of an AISI 316L steel nitrurated by DC pulsed plasma in an industrial machine in an atmosphere of 25% N 2 and 75% H 2 for 20 h at 400 o C by means of abrasion tests under different conditions in an A 135 Amsler-disk machine. In order to characterize the abraded samples microhardness, optic and scanning electron microscopy profiles to determine the abrasion mechanisms were performed. The results showed substantial improvement in the abrasion resistance of the nitrurated samples compared to the non nitrurated ones and the different abrasion mechanisms are discussed to explain the test results (CW)

  16. Hard coatings on magnesium alloys by sputter deposition using a pulsed d.c. bias voltage

    Energy Technology Data Exchange (ETDEWEB)

    Reiners, G. [Bundesanstalt fuer Materialforschung und -pruefung, Berlin (Germany); Griepentrog, M. [Bundesanstalt fuer Materialforschung und -pruefung, Berlin (Germany)

    1995-12-01

    An increasing use of magnesium-based light-metal alloys for various industrial applications was predicted in different technological studies. Companies in different branches have developed machine parts made of magnesium alloys (e.g. cars, car engines, sewing and knitting machines). Hence, this work was started to evaluate the ability of hard coatings obtained by physical vapour deposition (PVD) in combination with coatings obtained by electrochemical deposition to protect magnesium alloys against wear and corrosion. TiN hard coatings were deposited onto magnesium alloys by unbalanced magnetron sputter deposition. A bipolar pulsed d.c. bias voltage was used to limit substrate temperatures to 180 C during deposition without considerable loss of microhardness and adhesion. Adhesion, hardness and load-carrying capacity of TiN coatings deposited directly onto magnesium alloys are compared with the corresponding values of TiN coatings deposited onto substrates which had been coated electroless with an Ni-P alloy interlayer prior to the PVD. (orig.)

  17. Optimization of pulsed DC PACVD parameters: Toward reducing wear rate of the DLC films

    Science.gov (United States)

    Ebrahimi, Mansoureh; Mahboubi, Farzad; Naimi-Jamal, M. Reza

    2016-12-01

    The effect of pulsed direct current (DC) plasma-assisted chemical vapor deposition (PACVD) parameters such as temperature, duty cycle, hydrogen flow, and argon/CH4 flow ratio on the wear behavior and wear durability of the diamond-like carbon (DLC) films was studied by using response surface methodology (RSM). DLC films were deposited on nitrocarburized AISI 4140 steel. Wear rate and wear durability of the DLC films were examined with the pin-on-disk method. Field emission scanning electron microscopy, Raman spectroscopy, and nanoindentation techniques were used for studying wear mechanisms, chemical structure, and hardness of the DLC films. RSM results show that duty cycle is one of the important parameters that affect the wear rate of the DLC samples. The wear rate of the samples deposited with a duty cycle of >75% decreases with an increase in the argon/CH4 ratio. In contrast, for a duty cycle of <65%, the wear rate increases with an increase in the argon/CH4 ratio. The wear durability of the DLC samples increases with an increase in the duty cycle, hydrogen flow, and argon/CH4 flow ratio at the deposition temperature between 85 °C and 110 °C. Oxidation, fatigue, abrasive wear, and graphitization are the wear mechanisms observed on the wear scar of the DLC samples deposited with the optimum deposition conditions.

  18. Arc dynamics of a pulsed DC nitrogen rotating gliding arc discharge

    Science.gov (United States)

    Zhu, Fengsen; Zhang, Hao; Li, Xiaodong; Wu, Angjian; Yan, Jianhua; Ni, Mingjiang; Tu, Xin

    2018-03-01

    In this study, a novel pulsed direct current (DC) rotating gliding arc (RGA) plasma reactor co-driven by an external magnetic field and a tangential gas flow has been developed. The dynamic characteristics of the rotating gliding arc have been investigated by means of numerical simulation and experiment. The simulation results show that a highly turbulent vortex flow can be generated at the bottom of the RGA reactor to accelerate the arc rotation after arc ignition, whereas the magnitude of gas velocity declined significantly along the axial direction of the RGA reactor. The calculated arc rotation frequency (14.4 Hz) is reasonably close to the experimental result (18.5 Hz) at a gas flow rate of 10 l min-1. In the presence of an external magnet, the arc rotation frequency is around five times higher than that of the RGA reactor without using a magnet, which suggests that the external magnetic field plays a dominant role in the maintenance of the arc rotation in the upper zone of the RGA reactor. In addition, when the magnet is placed outside the reactor reversely to form a reverse external magnetic field, the arc can be stabilized at a fixed position in the inner wall of the outer electrode at a critical gas flow rate of 16 l min-1.

  19. Quantitative characterization of silicon- and aluminium oxynitride films produced by reactive dc-magnetron sputtering

    International Nuclear Information System (INIS)

    Dreer, S.

    2000-05-01

    The deposition of aluminum and silicon oxynitride films by reactive dc-magnetron sputtering was systematically planned by design of experiments, carried out and evaluated with the application of specialized statistics software. The influence of the deposition parameters on the resulting films was evaluated by multiple regression analysis. With the obtained data a model of the deposition process for the quantitative prediction of the deposition parameters necessary to obtain films with desired composition was built. This is also of technological importance, since the physical properties of the films strongly depend on their composition. Furthermore, the long term repeatability of the deposition process was implemented into the model. A precise and economic way for quantitative bulk analysis of silicon/aluminum, oxygen and nitrogen based on EPMA was presented and the use of data gained by the latter method is discussed for the calculation of relative sensitivity factors for SIMS and hf-SNMS. Advantages and disadvantages of SIMS, hf-SNMS, hf-GD-OES, and sputter AES were compared. The combination FT-IR/EPMA/SIMS at present offers the best possibility for a quantitative bulk and in depth distribution analysis of such films in the range of 20 to 1000 nm thickness. The films were also characterized by XRD and PAA. The refractive index and the growth rate of the films were determined by spectroscopic ellipsometry. With indentation by a nano hardness tester the hardness and the Young's modulus of the films were obtained. The results of these measurements were evaluated by statistical software. The dependencies of the physical properties on the deposition parameters and on the film thickness were evaluated and quantified. Furthermore, the dependencies of the physical properties on the film composition represented by the oxygen content were evaluated. (author)

  20. Corrosion mechanism and model of pulsed DC microarc oxidation treated AZ31 alloy in simulated body fluid

    Energy Technology Data Exchange (ETDEWEB)

    Gu Yanhong, E-mail: ygu2@alaska.edu [Department of Mechanical Engineering, University of Alaska Fairbanks, Fairbanks, AK 99775 (United States); Chen Chengfu [Department of Mechanical Engineering, University of Alaska Fairbanks, Fairbanks, AK 99775 (United States); Bandopadhyay, Sukumar [Department of Mining Engineering, University of Alaska Fairbanks, Fairbanks, AK 99775 (United States); Ning Chengyun [College of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Zhang Yongjun [Department of Mining Engineering, University of Alaska Fairbanks, Fairbanks, AK 99775 (United States); Guo Yuanjun [College of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China)

    2012-06-01

    This paper addresses the effect of pulse frequency on the corrosion behavior of microarc oxidation (MAO) coatings on AZ31 Mg alloys in simulated body fluid (SBF). The MAO coatings were deposited by a pulsed DC mode at four different pulse frequencies of 300 Hz, 500 Hz, 1000 Hz and 3000 Hz with a constant pulse ratio. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests were used for corrosion rate and electrochemical impedance evaluation. The corroded surfaces were examined by X-ray diffraction (XRD), X-ray fluorescence (XRF) and optical microscopy. All the results exhibited that the corrosion resistance of MAO coating produced at 3000 Hz is superior among the four frequencies used. The XRD spectra showed that the corrosion products contain hydroxyapatite, brucite and quintinite. A model for corrosion mechanism and corrosion process of the MAO coating on AZ31 Mg alloy in the SBF is proposed.

  1. Corrosion mechanism and model of pulsed DC microarc oxidation treated AZ31 alloy in simulated body fluid

    International Nuclear Information System (INIS)

    Gu Yanhong; Chen Chengfu; Bandopadhyay, Sukumar; Ning Chengyun; Zhang Yongjun; Guo Yuanjun

    2012-01-01

    This paper addresses the effect of pulse frequency on the corrosion behavior of microarc oxidation (MAO) coatings on AZ31 Mg alloys in simulated body fluid (SBF). The MAO coatings were deposited by a pulsed DC mode at four different pulse frequencies of 300 Hz, 500 Hz, 1000 Hz and 3000 Hz with a constant pulse ratio. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests were used for corrosion rate and electrochemical impedance evaluation. The corroded surfaces were examined by X-ray diffraction (XRD), X-ray fluorescence (XRF) and optical microscopy. All the results exhibited that the corrosion resistance of MAO coating produced at 3000 Hz is superior among the four frequencies used. The XRD spectra showed that the corrosion products contain hydroxyapatite, brucite and quintinite. A model for corrosion mechanism and corrosion process of the MAO coating on AZ31 Mg alloy in the SBF is proposed.

  2. Pulsed EPR studies of small reactive radicals produced by ionizing radiation

    International Nuclear Information System (INIS)

    Lawler, R.G.

    1985-01-01

    For several years we have participated in a collaborative research effort to apply the pulsed EPR-pulse radiolysis technique to several problems associated with the dynamics of small reactive radicals formed during radiolysis of aqueous solutions using 3 MeV electrons from a Van de Graaff accelerator. We will discuss experimental techniques and applications arising from this work, with particular emphasis on problems requiring high initial radical concentrations and EPR time resolution of one microsecond or better. 2 figs., 2 tabs

  3. Deposition of zinc oxide thin films by reactive pulsed laser ablation

    Czech Academy of Sciences Publication Activity Database

    Bílková, Petra; Zemek, Josef; Mitu, B.; Marotta, V.; Orlando, S.

    2006-01-01

    Roč. 252, - (2006), s. 4604-4609 ISSN 0169-4332 Grant - others:NATO-CNR Outreach Fellowships Programm 2001(XE) 219.34 Institutional research plan: CEZ:AV0Z10100521 Keywords : reactive pulsed laser deposition * zinc oxide * thin films Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.436, year: 2006

  4. Guanosine radical reactivity explored by pulse radiolysis coupled with transient electrochemistry.

    Science.gov (United States)

    Latus, A; Alam, M S; Mostafavi, M; Marignier, J-L; Maisonhaute, E

    2015-06-04

    We follow the reactivity of a guanosine radical created by a radiolytic electron pulse both by spectroscopic and electrochemical methods. This original approach allows us to demonstrate that there is a competition between oxidation and reduction of these intermediates, an important result to further analyse the degradation or repair pathways of DNA bases.

  5. Analysis of rod drop and pulsed source measurements of reactivity in the Winfrith SGHWR

    International Nuclear Information System (INIS)

    Brittain, I.

    1970-05-01

    Reactivity measurements by the rod-drop and pulsed source methods in the Winfrith SGHWR are seriously affected by spatial harmonics. A method of calculation is described which enables the spatial harmonics to be calculated in non-uniform cores in two or three dimensions, and thus allows a much more rigorous analysis of the experimental results than the usual point model. The method is used to analyse all the rod-drop measurements made during commissioning of the Winfrith SGHWR, and to comment on the results of pulsed source measurements. The reactivity worths of banks of ten and twelve shut-down tubes deduced from rod-drop and pulsed source experiments are in satisfactory agreement with each other and also with AIMAZ calculated values. The ability to calculate higher spatial harmonics in nonuniform cores is thought to be new, and may have a wider application to reactor kinetics through the method of Modal Analysis. (author)

  6. A novel non-sequential hydrogen-pulsed deep reactive ion etching of silicon

    International Nuclear Information System (INIS)

    Gharooni, M; Mohajerzadeh, A; Sandoughsaz, A; Khanof, S; Mohajerzadeh, S; Asl-Soleimani, E

    2013-01-01

    A non-sequential pulsed-mode deep reactive ion etching of silicon is reported that employs continuous etching and passivation based on SF 6 and H 2 gases. The passivation layer, as an important step for deep vertical etching of silicon, is feasible by hydrogen pulses in proper time-slots. By adjusting the etching parameters such as plasma power, H 2 and SF 6 flows and hydrogen pulse timing, the process can be controlled for minimum underetch and high etch-rate at the same time. High-aspect-ratio features can be realized with low-density plasma power and by controlling the reaction chemistry. The so-called reactive ion etching lag has been minimized by operating the reactor at higher pressures. X-ray photoelectron spectroscopy and scanning electron microscopy have been used to study the formation of the passivation layer and the passivation mechanism. (paper)

  7. Time-resolved electrical measurements of a pulsed-dc methane discharge used in diamond-like carbon films production

    International Nuclear Information System (INIS)

    Corbella, C.; Polo, M.C.; Oncins, G.; Pascual, E.; Andujar, J.L.; Bertran, E.

    2005-01-01

    Amorphous hydrogenated carbon (a-C:H) thin films were obtained at room temperature via asymmetric bipolar pulsed-dc methane glow discharge. The power frequency values were varied from 100 to 200 kHz and the maximum amplitude voltage from -600 to -1400 V. Such films present diamond-like carbon (DLC) properties [J.L. Andujar, M. Vives, C. Corbella, E. Bertran, Diamond Relat. Mater. 12 (2003) 98]. The plasma, powered by a pulse frequency of 100 kHz, was electrically studied by a Langmuir probe. The next parameters were calculated within the pulse cycle from I-V measurements with 1 μs resolution: plasma and floating potentials, electron temperature, and electron and ion densities. The presence of a population of hot electrons (10 eV) was detected at high bias voltage region. The density of cold electrons grows one order of magnitude after each negative pulse, whereas the ion density suffers a prompt increase during each positive pulse. The surface topography of DLC films was scanned by atomic force microscopy (AFM). A smoothly varying friction coefficient (between 0.2 and 0.3) was measured by AFM in contact mode. X-ray reflectivity (XRR) analysis provided a wide characterization of the films, involving density, thickness and roughness. The C/H ratio, as directly obtained by elemental analysis (EA), shows an increase at higher bias voltages. All these features are discussed in terms of process parameters varied in film growth

  8. Effect of geometry on the surface characteristics of steel components AISI 4140 nitrited by DC-pulsed plasma

    International Nuclear Information System (INIS)

    Calahonra, C; De Las Heras, E; De La Serena, F; Corengia, P; Ybarra, G; Svoboda, H

    2004-01-01

    Steel AISI 4140 pieces containing cylindrical pinholes with different diameters and depths were nitrited by plasma, in an atmosphere of 25% N 2 + 75% H 2 under a DC-pulsed glow discharge for 15 h. The samples were nitrited to study the influence of the sizes of the pinholes on the uniformity of the compound layer, on the depth of the zone of diffusion and on the surface and subsurface micro-hardness. The results showed that nitriding pieces with pinholes introduces variations in the electric parameters and modifies the uniformity of the coat of compounds formed, altering the mechanical properties of the surface and subsurface (CW)

  9. DC-pulsed voltage electrochemical method based on duty cycle self-control for producing TERS gold tips

    International Nuclear Information System (INIS)

    Vasilchenko, V E; Kharintsev, S S; Salakhov, M Kh

    2013-01-01

    This paper presents a modified dc-pulsed low voltage electrochemical method in which a duty cycle is self tuned while etching. A higher yield of gold tips suitable for performing tip-enhanced Raman scattering (TERS) measurements is demonstrated. The improvement is caused by the self-control of the etching rate along the full surface of the tip. A capability of the gold tips to enhance a Raman signal is exemplified by TERS spectroscopy of single walled carbon nanotubes bundle, sulfur and vanadium oxide

  10. Dielectric properties of DC reactive magnetron sputtered Al{sub 2}O{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Prasanna, S. [Thin Film Center, Department of Physics, PSG College of Technology, Coimbatore, 641 004 (India); Mohan Rao, G. [Department of Instrumentation, Indian Institute of Science (IISc), Bangalore, 560 012 (India); Jayakumar, S., E-mail: s_jayakumar_99@yahoo.com [Thin Film Center, Department of Physics, PSG College of Technology, Coimbatore, 641 004 (India); Kannan, M.D. [Thin Film Center, Department of Physics, PSG College of Technology, Coimbatore, 641 004 (India); Ganesan, V. [Low Temperature Lab, UGC-DAE Consortium for Scientific Research (CSR), Indore, 452 017 (India)

    2012-01-31

    Alumina (Al{sub 2}O{sub 3}) thin films were sputter deposited over well-cleaned glass and Si < 100 > substrates by DC reactive magnetron sputtering under various oxygen gas pressures and sputtering powers. The composition of the films was analyzed by X-ray photoelectron spectroscopy and an optimal O/Al atomic ratio of 1.59 was obtained at a reactive gas pressure of 0.03 Pa and sputtering power of 70 W. X-ray diffraction results revealed that the films were amorphous until 550 Degree-Sign C. The surface morphology of the films was studied using scanning electron microscopy and the as-deposited films were found to be smooth. The topography of the as-deposited and annealed films was analyzed by atomic force microscopy and a progressive increase in the rms roughness of the films from 3.2 nm to 4.53 nm was also observed with increase in the annealing temperature. Al-Al{sub 2}O{sub 3}-Al thin film capacitors were then fabricated on glass substrates to study the effect of temperature and frequency on the dielectric property of the films. Temperature coefficient of capacitance, AC conductivity and activation energy were determined and the results are discussed. - Highlights: Black-Right-Pointing-Pointer Al{sub 2}O{sub 3} thin films were deposited by DC reactive magnetron sputtering. Black-Right-Pointing-Pointer The films were found to be amorphous up to annealing temperature of 550 C. Black-Right-Pointing-Pointer An increase in rms roughness of the films was observed with annealing. Black-Right-Pointing-Pointer Al-Al{sub 2}O{sub 3}-Al thin film capacitors were fabricated and dielectric constant was 7.5. Black-Right-Pointing-Pointer The activation energy decreased with increase in frequency.

  11. Isolated PWM DC-AC SICAM with an active capacitive voltage clamp[Pulse Density Modulated; Pulse Width Modulation

    Energy Technology Data Exchange (ETDEWEB)

    Ljusev, P.

    2004-03-15

    In this report an isolated PWM DC-AC SICAM with an active capacitive voltage clamp is presented. AC-DC power supply is implemented in its simplest form: diode rectifier followed by a medium-size charge-storage capacitors and possibly with an EMC filter on the mains entrance. Isolation from the AC mains is achieved using a high frequency (HF) transformer, whose voltages are not audio-modulated. The latter simplifies the design and is expected to have many advantages over the approach where the transformer voltages are modulated in regards to the audio signal reference. Input stage is built as a DC-AC inverter (push-pull, half-bridge or a full-bridge) and operated with 50% duty cycle, with all the challenges to avoid transformer saturation and obtain symmetrical operation. On the secondary side the output section is implemented as rectifier+inverter AC-AC stage, i.e. a true bidirectional bridge, which operation is aimed towards amplification of the audio signal. In order to solve the problem with the commutation of the load current, a dead time between the incoming and outgoing bidirectional switch is implemented, while a capacitive voltage clamp is used to keep the induced overvoltage to reasonable levels. The energy stored in the clamping capacitor is not wasted as in the dissipative clamps, but is rather transferred back to the primary side for further processing using an auxiliary isolated single-switch converter, i.e. an active clamping technique is used. (au)

  12. Scaled-Up Nonequilibrium Air Plasmas Generated by DC and Pulsed Discharges

    Science.gov (United States)

    2010-09-08

    memory effect - these electrons can remain from previous pulse thanks to the high f . During the short spark pulse, Rp drops down to few hundred ohms ...Morvova, E. Marode, and I. Morva. J. Phys. D: Appl. Phys., 33:3198, 2000. [23] Y Akishev, O Goossens, T Callebaut, C Leys , A Napartovich, and N

  13. Method of analysis to determine subcritical reactivity from the pulsed neutron experiment

    International Nuclear Information System (INIS)

    Parks, P.B.

    1975-06-01

    The published methods for the deduction of reactivity from pulsed neutron experiments on subcritical reactors are reviewed. Each method is categorized as inherently yielding a result that is either spatially independent or spatially dependent. The spatially independent results are formally identical with the static reactivity; the result does not depend, in principle, on the location of either the pulsed neutron source or the neutron detector during data collection. The spatially dependent results only approximate the static reactivity; the results are affected, in varying degrees, by the locations of the source and detector. Among the techniques yielding spatially independent results are the Space-Time method of Parks and Stewart and the Inhour method of Preskitt et al. Spatially dependent results are obtained with the Sjoestrand, Gozani, and Garelis-Russell methods which are examined with and without the kinetic distortion corrections given by Becker and Quisenberry. Intercomparisons of all methods are made with reference to pulsed neutron experiments on both unreflected and reflected reactors. Recommendations are made concerning the best choice of method under the various experimental conditions that are likely to be encountered. 14 references. (U.S.)

  14. Plasma surface treatment to improve surface charge accumulation and dissipation of epoxy resin exposed to DC and nanosecond-pulse voltages

    Science.gov (United States)

    Zhang, Cheng; Lin, Haofan; Zhang, Shuai; Xie, Qin; Ren, Chengyan; Shao, Tao

    2017-10-01

    In this paper, deposition by non-thermal plasma is used as a surface modification technique to change the surface characteristics of epoxy resin exposed to DC and nanosecond-pulse voltages. The corresponding surface characteristics in both cases of DC and nanosecond-pulse voltages before and after the modification are compared and investigated. The measurement of the surface potential provides the surface charge distribution, which is used to show the accumulation and dissipation process of the surface charges. Morphology observations, chemical composition and electrical parameters measurements are used to evaluate the treatment effects. The experimental results show that, before the plasma treatment, the accumulated surface charges in the case of the DC voltage are more than that in the case of the nanosecond-pulse voltage. Moreover, the decay rate of the surface charges for the DC voltage is higher than that for the nanosecond-pulse voltage. However, the decay rate is no more than 41% after 1800 s for both types of voltages. After the plasma treatment, the maximum surface potentials decrease to 57.33% and 32.57% of their values before treatment for the DC and nanosecond-pulse voltages, respectively, indicating a decrease in the accumulated surface charges. The decay rate exceeds 90% for both types of voltages. These changes are mainly attributed to a change in the surface nanostructure, an increase in conductivity, and a decrease in the depth of energy level.

  15. Plasma surface treatment to improve surface charge accumulation and dissipation of epoxy resin exposed to DC and nanosecond-pulse voltages

    International Nuclear Information System (INIS)

    Zhang, Cheng; Lin, Haofan; Zhang, Shuai; Ren, Chengyan; Shao, Tao; Xie, Qin

    2017-01-01

    In this paper, deposition by non-thermal plasma is used as a surface modification technique to change the surface characteristics of epoxy resin exposed to DC and nanosecond-pulse voltages. The corresponding surface characteristics in both cases of DC and nanosecond-pulse voltages before and after the modification are compared and investigated. The measurement of the surface potential provides the surface charge distribution, which is used to show the accumulation and dissipation process of the surface charges. Morphology observations, chemical composition and electrical parameters measurements are used to evaluate the treatment effects. The experimental results show that, before the plasma treatment, the accumulated surface charges in the case of the DC voltage are more than that in the case of the nanosecond-pulse voltage. Moreover, the decay rate of the surface charges for the DC voltage is higher than that for the nanosecond-pulse voltage. However, the decay rate is no more than 41% after 1800 s for both types of voltages. After the plasma treatment, the maximum surface potentials decrease to 57.33% and 32.57% of their values before treatment for the DC and nanosecond-pulse voltages, respectively, indicating a decrease in the accumulated surface charges. The decay rate exceeds 90% for both types of voltages. These changes are mainly attributed to a change in the surface nanostructure, an increase in conductivity, and a decrease in the depth of energy level. (paper)

  16. Electrical and optical properties of indium tin oxide thin films deposited on unheated substrates by d.c. reactive sputtering

    International Nuclear Information System (INIS)

    Karasawa, T.; Miyata, Y.

    1993-01-01

    Transparent conducting thin films of indium tin oxide (ITO) have been deposited by d.c. reactive planar magnetron sputtering by using metal In-Sn alloy target in an Ar-O 2 gas mixture. The study demonstrates that the deposition on unheated substrates achieved sheet resistance of as low as about 50-60 Ω/□ (or a resistivity of about 7 x 10 -4 Ω cm), and visible transmission of about 90% for a wavelength of 420 nm. The effects of heat treatment at 450 C in air depends on the deposition conditions of the as-deposited ITO films. Although annealing improves the properties of as-deposited ITO films which were deposited with non-optimum conditions, the optimized condition for the formation of the film in the as-deposited state is essential to obtain a high quality transparent conducting coating. (orig.)

  17. Decorative black TiCxOy film fabricated by DC magnetron sputtering without importing oxygen reactive gas

    Science.gov (United States)

    Ono, Katsushi; Wakabayashi, Masao; Tsukakoshi, Yukio; Abe, Yoshiyuki

    2016-02-01

    Decorative black TiCxOy films were fabricated by dc (direct current) magnetron sputtering without importing the oxygen reactive gas into the sputtering chamber. Using a ceramic target of titanium oxycarbide (TiC1.59O0.31), the oxygen content in the films could be easily controlled by adjustment of total sputtering gas pressure without remarkable change of the carbon content. The films deposited at 2.0 and 4.0 Pa, those are higher pressure when compared with that in conventional magnetron sputtering, showed an attractive black color. In particular, the film at 4.0 Pa had the composition of TiC1.03O1.10, exhibited the L* of 41.5, a* of 0.2 and b* of 0.6 in CIELAB color space. These values were smaller than those in the TiC0.29O1.38 films (L* of 45.8, a* of 1.2 and b* of 1.2) fabricated by conventional reactive sputtering method from the same target under the conditions of gas pressure of 0.3 Pa and optimized oxygen reactive gas concentration of 2.5 vol.% in sputtering gas. Analysis of XRD and XPS revealed that the black film deposited at 4.0 Pa was the amorphous film composed of TiC, TiO and C. The adhesion property and the heat resisting property were enough for decorative uses. This sputtering process has an industrial advantage that the decorative black coating with color uniformity in large area can be easily obtained by plain operation because of unnecessary of the oxygen reactive gas importing which is difficult to be controlled uniformly in the sputtering chamber.

  18. Investigation of carbon cathode surface before and after the passage of combined dc vacuum arc with superimposed high-current arc pulses

    International Nuclear Information System (INIS)

    Zavaleyev, V.; Walkowicz, J.; Moszynski, D.

    2016-01-01

    The paper presents the results of studies of carbon cathode surface before and after the passage of the combined DC vacuum-arc with superimposed high-current arc pulses. Investigations of surface morphology of carbon cathode showed, that secondary nuclei of high-density are formed after passing of the combined DC-pulse vacuum-arc, which results in the formation of a globular structures. The phase structure analysis by Raman spectroscopy showed that even at a minimum operation time (5 s) of the combined DC-pulse vacuum-arc broadening of the peaks 1355 and 1583 cm-1 occurs, which means that the carbon cathode surface undergo phase transformation. Results obtained by XPS spectroscopy demonstrate that the globular structures formed on the cathode surface are composed of sp 3 -bonded carbon atoms and carbon-oxygen bonds.

  19. Bioactivity response of Ta{sub 1-x}O{sub x} coatings deposited by reactive DC magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Almeida Alves, C.F., E-mail: cristiana.alves@fisica.uminho.pt [GRF-CFUM, Physics Departament, University of Minho, Campus of Azurem, Guimaraes 4800-058 (Portugal); Cavaleiro, A. [SEG-CEMUC, Mechanical Engineering Department, University of Coimbra, Coimbra 3030-788 (Portugal); Carvalho, S. [GRF-CFUM, Physics Departament, University of Minho, Campus of Azurem, Guimaraes 4800-058 (Portugal); SEG-CEMUC, Mechanical Engineering Department, University of Coimbra, Coimbra 3030-788 (Portugal)

    2016-01-01

    The use of dental implants is sometimes accompanied by failure due to periimplantitis disease and subsequently poor esthetics when soft–hard tissue margin recedes. As a consequence, further research is needed for developing new bioactive surfaces able to enhance the osseous growth. Tantalum (Ta) is a promising material for dental implants since, comparing with titanium (Ti), it is bioactive and has an interesting chemistry which promotes the osseointegration. Another promising approach for implantology is the development of implants with oxidized surfaces since bone progenitor cells interact with the oxide layer forming a diffusion zone due to its ability to bind with calcium which promotes a stronger bond. In the present report Ta-based coatings were deposited by reactive DC magnetron sputtering onto Ti CP substrates in an Ar + O{sub 2} atmosphere. In order to assess the osteoconductive response of the studied materials, contact angle and in vitro tests of the samples immersed in Simulated Body Fluid (SBF) were performed. Structural results showed that oxide phases where achieved with larger amounts of oxygen (70 at.% O). More compact and smooth coatings were deposited by increasing the oxygen content. The as-deposited Ta coating presented the most hydrophobic character (100°); with increasing oxygen amount contact angles progressively diminished, down to the lowest measured value, 63°. The higher wettability is also accompanied by an increase on the surface energy. Bioactivity tests demonstrated that highest O-content coating, in good agreement with wettability and surface energy values, showed an increased affinity for apatite adhesion, with higher Ca/P ratio formation, when compared to the bare Ti substrates. - Highlights: • Ta{sub 1-x}O{sub x} coatings were deposited by reactive DC magnetron sputtering. • Amorphous oxide phases were achieved with higher oxygen amounts. • Contact angles progressively diminished, with increasing oxygen content. • Ta

  20. Pulse Width Modulator Controller Design for a Brushless DC Motor Position Servo.

    Science.gov (United States)

    1987-06-01

    REQC1,REQC2, lAB, ZEC , ICA, 4. + PVAO, Fy5, PVCO,NODE,TRIG1,TRIG2,TRIG3 ,TRIG4, + TRIG5,TRIGS,RA,PLUGVAIMD,VBIND,VCIND) c call TCONST(ICQl, .75-SWl...DC Motors, Master’s Thesis, Naval Postgraduate School, Monterey, Ca., September 1984. 2. MacMillan, Peter N., A CSMP Commutation Model for .’. Design

  1. The dynamics of Al/Pt reactive multilayer ignition via pulsed-laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, Ryan D.; Reeves, Robert V.; Yarrington, Cole D.; Adams, David P. [Sandia National Laboratories, Albuquerque, New Mexico 87123 (United States)

    2015-12-07

    Reactive multilayers consisting of alternating layers of Al and Pt were irradiated by single laser pulses ranging from 100 μs to 100 ms in duration, resulting in the initiation of rapid, self-propagating reactions. The threshold intensities for ignition vary with the focused laser beam diameter, bilayer thickness, and pulse length and are affected by solid state reactions and conduction of heat away from the irradiated regions. High-speed photography was used to observe ignition dynamics during irradiation and elucidate the effects of heat transfer into a multilayer foil. For an increasing laser pulse length, the ignition process transitioned from a more uniform to a less uniform temperature profile within the laser-heated zone. A more uniform temperature profile is attributed to rapid heating rates and heat localization for shorter laser pulses, and a less uniform temperature profile is due to slower heating of reactants and conduction during irradiation by longer laser pulses. Finite element simulations of laser heating using measured threshold intensities indicate that micron-scale ignition of Al/Pt occurs at low temperatures, below the melting point of both reactants.

  2. Substantial difference in target surface chemistry between reactive dc and high power impulse magnetron sputtering

    Science.gov (United States)

    Greczynski, G.; Mráz, S.; Schneider, J. M.; Hultman, L.

    2018-02-01

    The nitride layer formed in the target race track during the deposition of stoichiometric TiN thin films is a factor 2.5 thicker for high power impulse magnetron sputtering (HIPIMS), compared to conventional dc processing (DCMS). The phenomenon is explained using x-ray photoelectron spectroscopy analysis of the as-operated Ti target surface chemistry supported by sputter depth profiles, dynamic Monte Carlo simulations employing the TRIDYN code, and plasma chemical investigations by ion mass spectrometry. The target chemistry and the thickness of the nitride layer are found to be determined by the implantation of nitrogen ions, predominantly N+ and N2+ for HIPIMS and DCMS, respectively. Knowledge of this method-inherent difference enables robust processing of high quality functional coatings.

  3. Social support and loneliness in college students: effects on pulse pressure reactivity to acute stress.

    Science.gov (United States)

    O'Donovan, Aoife; Hughes, Brian

    2007-01-01

    Socially supportive relationships at university may buffer against psychological stress in students, particularly in those experiencing loneliness. To examine the relation of social support at university and loneliness with pulse pressure (PP) reactivity to acute psychological stress in a sample of first-year undergraduate students. Sixty-five female, adolescent, first-year university students. Pulse pressure (PP) was calculated as the arithmetic difference between systolic blood pressure and diastolic blood pressure, which were measured during a resting baseline and during a stressful reading task. The difference between baseline and reading task PP represents PP reactivity. The Social Support at University Scale (SSUS) was used to assess social support availability in university, and the Revised UCLA Loneliness Scale was used to assess loneliness. Hierarchical linear regression was used to examine main and interactive effects of SSUS and loneliness on PP change scores, and simple slopes were computed to assist in the interpretation of interaction effects. Social support at university was associated with lower PP reactivity in students reporting medium (t = -2.03, p = .04) or high levels of loneliness (t = -2.93, p = .004), but not in those reporting low levels of loneliness (t = -0.20, p = .83). Psychosocial interventions designed to increase social support available at university, and targeted at students experiencing loneliness may buffer against the harmful effects of acute stressors in lonely first-year students.

  4. Microstructural Analysis of TiAl x N y O z Coatings Fabricated by DC Reactive Sputtering

    Science.gov (United States)

    García-González, L.; Hernández-Torres, J.; Flores-Ramírez, N.; Martínez-Castillo, J.; García-Ramírez, P. J.; Muñoz-Saldaña, J.; Espinoza-Beltrán, F. J.

    2009-02-01

    TiAl x N y O z coatings were prepared by DC reactive sputtering on AISI D2 tool steel substrates, using a target of Ti-Al-O fabricated from a mixture of powders of Ti (22.60 wt.%), Al (24.77 wt.%), and O (52.63 wt.%). The coatings were deposited on substrates at room temperature in a reactive atmosphere of nitrogen and argon under a pressure of 8.5 × 10-3 mbar. X-ray diffraction, electron dispersive spectroscopy, Raman scattering, and nanoindentation techniques were employed to investigate the coatings. The results show that the increment in the nitrogen flow affects the structure and the mechanical properties of the coatings. The sample with the lowest nitrogen flow presented the highest hardness (10.5 GPa) and the Young’s modulus (179.5 GPa). The hardness of the coatings TiAl x N y O z as a function of crystalline grain size shows a behavior consistent with the Hall-Petch relation.

  5. Resonance hairpin and Langmuir probe-assisted laser photodetachment measurements of the negative ion density in a pulsed dc magnetron discharge

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, James W.; Dodd, Robert; You, S.-D.; Sirse, Nishant; Karkari, Shantanu Kumar [Department of Electrical Engineering and Electronics, University of Liverpool, Liverpool (United Kingdom); National Centre for Plasma Science and Technology, Dublin City University, Dublin 9, Republic of Ireland (Ireland); National Centre for Plasma Science and Technology, Dublin City University, Dublin 9, Republic of Ireland and Institute for Plasma Research, Bhat Gandhinagar, Gujarat (India)

    2011-05-15

    The time-resolved negative oxygen ion density n{sub -} close to the center line in a reactive pulsed dc magnetron discharge (10 kHz and 50% duty cycle) has been determined for the first time using a combination of laser photodetachment and resonance hairpin probing. The discharge was operated at a power of 50 W in 70% argon and 30% oxygen gas mixtures at 1.3 Pa pressure. The results show that the O{sup -} density remains pretty constant during the driven phase of the discharge at values typically below 5x10{sup 14} m{sup -3}; however, in the off-time, the O{sup -} density grows reaching values several times those in the on-time. This leads to the negative ion fraction (or degree of electronegativity) {alpha}=n{sub -}/n{sub e} being higher in the off phase (maximum value {alpha}{approx}1) than in the on phase ({alpha}=0.05-0.3). The authors also see higher values of {alpha} at positions close to the magnetic null than in the more magnetized region of the plasma. This fractional increase in negative ion density during the off-phase is attributed to the enhanced dissociative electron attachment of highly excited oxygen molecules in the cooling plasma. The results show that close to the magnetic null the photodetached electron density decays quickly after the laser pulse, followed by a slow decay over a few microseconds governed by the negative ion temperature. However, in the magnetized regions of the plasma, this decay is more gradual. This is attributed to the different cross-field transport rates for electrons in these two regions. The resonance hairpin probe measurements of the photoelectron densities are compared directly to photoelectron currents obtained using a conventional Langmuir probe. There is good agreement in the general trends, particularly in the off-time.

  6. Electron beam induced coloration and luminescence in layered structure of WO3 thin films grown by pulsed dc magnetron sputtering

    International Nuclear Information System (INIS)

    Karuppasamy, A.; Subrahmanyam, A.

    2007-01-01

    Tungsten oxide thin films have been deposited by pulsed dc magnetron sputtering of tungsten in argon and oxygen atmosphere. The as-deposited WO 3 film is amorphous, highly transparent, and shows a layered structure along the edges. In addition, the optical properties of the as-deposited film show a steplike behavior of extinction coefficient. However, the electron beam irradiation (3.0 keV) of the as-deposited films results in crystallization, coloration (deep blue), and luminescence (intense red emission). The above changes in physical properties are attributed to the extraction of oxygen atoms from the sample and the structural modifications induced by electron bombardment. The present method of coloration and luminescence has a potential for fabricating high-density optical data storage device

  7. Investigation and control of dc arc jet instabilities to obtain a self-sustained pulsed laminar arc jet

    International Nuclear Information System (INIS)

    Krowka, J; Rat, V; Coudert, J F

    2013-01-01

    The uncontrolled arc plasma instabilities in suspension plasma spraying or solution precursor plasma spraying cause non-homogeneous plasma treatments of material during their flight and also on coatings during their formation. This paper shows that the arc motion in dc plasma torches mainly originates in two main modes of oscillation (Helmholtz and restrike modes). The emphasis is put on the restrike mode in which the time component is extracted after building up and applying a numerical filter to raw arc voltage signals. The dependence of re-arcing events on experimental parameters is analysed in the frame of a phenomenological restrike model. It is shown that when the restrike frequency reaches the Helmholtz one, both modes are locked together and a pulsed arc jet is generated. (paper)

  8. InTaO4-based nanostructures synthesized by reactive pulsed laser ablation

    International Nuclear Information System (INIS)

    Yoshida, Takehito; Toyoyama, Hirokazu; Umezu, Ikurou; Sugimura, Akira

    2008-01-01

    Nanostructured Ni-doped indium-tantalum-oxides (InTaO 4 ) were synthesized by a reactive pulsed laser ablation process, aiming at the final goal of direct splitting of water under visible sunbeam irradiation. The third harmonics beam of a Nd:YAG laser was focused onto a sintered In 0.9 Ni 0.1 TaO 4-δ target in pure oxygen background gases (0.05-1.00 Torr). Increasing the oxygen gas pressure, via thin films having nanometer-sized strong morphologies, single-crystalline nanoparticles were synthesized in the reactive vapor phases. The nanostructured deposited materials have the monoclinic layered wolframite-type structure of bulk InTaO 4 , without oxygen deficiency. (orig.)

  9. Control Rod Reactivity Measurements in the Aagesta Reactor with the Pulsed Neutron Method

    Energy Technology Data Exchange (ETDEWEB)

    Bjoereus, K

    1969-07-01

    An extensive series of control rod measurements was made in the Aagesta reactor during the low power experimental period following the first criticality. This report describes the part of these investigations made with the pulsed neutron method, comprising nearly 300 measurements. The main objective was the determination of control rod reactivity worths for different rods and groups of rods, but some supplementary measurements were also made, e.g. a determination of the prompt neutron decay constant for the delayed critical condition and four different cores. The cores consisted of 20, 32, 68, and 140 fuel elements respectively, and measurements were made at room temperature and with the moderator level close to critical for each core, and for the 140-element core also with full moderator height and at the temperatures 140 deg C and 215 deg C. Both fully and partly inserted control rod groups were investigated. The measurements at critical water level give directly the control rod reactivity worths, whereas those with full water height give the shut-down reactivity. A comparison was made between measured reactivity worths for a number of rod groups and those calculated with the HETERO code. The prompt neutron decay constant at delayed criticality {alpha}{sub 0}={beta}/l, for the full core at 215 deg C was found to be 9.60 {+-} 0.30/sec, corresponding to l = 0.76 {+-} 0.02 msec. The shut-down reactivity with 16 coarse control rods in pos. A-D 22, 40-04, 44, 26 is -5% at 25 deg C and -13% at 215 deg C. The relative error is usually around 8% in the reactivity worths, originating mainly from the higher harmonics content in the measured curves.

  10. Elimination of DC-Link Current Ripple for Modular Multilevel Converters With Capacitor Voltage-Balancing Pulse-Shifted Carrier PWM

    DEFF Research Database (Denmark)

    Deng, Fujin; Chen, Zhe

    2015-01-01

    The modular multilevel converter (MMC) is attractive for medium- and high-power applications because of its high modularity, availability, and power quality. In this paper, the current ripple on the dc link of the three-phase MMC derived from the phase-shifted carrier-based pulse-width modulation...

  11. Growth and characterization of polycrystalline Ge1-xCx by reactive pulsed laser deposition

    International Nuclear Information System (INIS)

    Hernandez, M.P.; Farias, M.H.; Castillon, F.F.; Diaz, Jesus A.; Avalos, M.; Ulloa, L.; Gallegos, J.A.; Yee-Madeiros, H.

    2011-01-01

    Polycrystalline thin films of Ge-C were grown on Si (1 1 1) substrates by means of reactive pulsed laser deposition with methane pressure of 100 mTorr. Effect substrate temperature, T s , on C incorporation to substitutional sites (x) in Ge 1-x C x was investigated systematically by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyzes. The substrate temperatures were ranging from 250 to 400 deg. C. The substitutional C composition x in the films by XRD were estimated using the Vegard's linear law. The maximum value of x calculated by XRD was 0.032 for T s of 350 deg. C. The position of the C 1s peak at 283.4 eV in the XPS spectrum confirmed the germanium-carbon alloys. XRD measurements indicated that x increased with T s from 250 deg. C to 350 deg. C. At T s = 400 deg. C, the estimation of x was lowered. However, the C content calculated by XPS analyzes increased with T s being more these values than substitutional C composition x. XPS and XRD analyzes demonstrate that the remaining C atoms are incorporated to interstitial sites. The use of the T s plays important roles in the incorporation of substitutional C and in restraining C-cluster formation in the reactive pulsed laser deposition growth of Ge-C/Si.

  12. Pulsed laser ablation of borax target in vacuum and hydrogen DC glow discharges

    Science.gov (United States)

    Kale, A. N.; Miotello, A.; Mosaner, P.

    2006-09-01

    The aim of our experiment was to produce a material with B sbnd H bonds for applications in hydrogen storage and generation. By using KrF excimer laser ( λ = 248 nm) ablation of borax (Na 2B 4O 7) target, thin films were deposited on KBr and silicon substrates. Ablation was performed both in vacuum and in hydrogen atmosphere. DC glow discharge technique was utilized to enhance hydrogen gas ionization. Experiments were performed using laser fluence from 5 to 20 J/cm 2. Films were deposited under gas pressure of 1 × 10 -5 to 5 × 10 -2 mbar and substrate temperatures of 130-450 °C. Scanning electron microscopy analysis of films showed presence of circular particulates. Film thickness, roughness and particulates number increased with increase in laser fluence. Energy dispersive X-ray spectroscopy analysis shows that sodium content in the particulates is higher than in the target. This effect is discussed in terms of atomic arrangements (both at surface and bulk) in systems where ionic and covalent bonds are present and by looking at the increased surface/bulk ratio of the particulates with respect to the deposited films. The Fourier transform infrared spectroscopy measurements showed presence of B sbnd O stretching and B sbnd O sbnd B bending bonds. Possible reasons for absence of B sbnd H bonds are attributed to binding enthalpy of the competing molecules.

  13. Electrical and optical properties of reactive dc magnetron sputtered silver-doped indium oxide thin films: role of oxygen

    International Nuclear Information System (INIS)

    Subrahmanyam, A.; Barik, U.K.

    2006-01-01

    Silver-doped indium oxide thin films have been prepared on glass and quartz substrates at room temperature (300 K) by a reactive dc magnetron sputtering technique using an alloy target of pure indium and silver (80:20 at. %). During sputtering, the oxygen flow rates are varied in the range 0.00-2.86 sccm keeping the magnetron power constant at 40 W. The resistivity of these films is in the range 10 0 -10 -3 Ωcm and they show a negative temperature coefficient of resistivity. The films exhibit p-type conductivity at an oxygen flow rate of 1.71 sccm. The work function of these silver-indium oxide films has been measured by a Kelvin probe technique. The refractive index of the films (at 632.8 nm) varies in the range 1.13-1.20. Silver doping in indium oxide narrows the band gap of indium oxide (3.75 eV). (orig.)

  14. Electrical and optical properties of reactive dc magnetron sputtered silver-doped indium oxide thin films: role of oxygen

    Energy Technology Data Exchange (ETDEWEB)

    Subrahmanyam, A; Barik, U K [Indian Institute of Technology Madras, Semiconductor Physics Laboratory, Department of Physics, Chennai (India)

    2006-07-15

    Silver-doped indium oxide thin films have been prepared on glass and quartz substrates at room temperature (300 K) by a reactive dc magnetron sputtering technique using an alloy target of pure indium and silver (80:20 at. %). During sputtering, the oxygen flow rates are varied in the range 0.00-2.86 sccm keeping the magnetron power constant at 40 W. The resistivity of these films is in the range 10{sup 0}-10{sup -3} {omega}cm and they show a negative temperature coefficient of resistivity. The films exhibit p-type conductivity at an oxygen flow rate of 1.71 sccm. The work function of these silver-indium oxide films has been measured by a Kelvin probe technique. The refractive index of the films (at 632.8 nm) varies in the range 1.13-1.20. Silver doping in indium oxide narrows the band gap of indium oxide (3.75 eV). (orig.)

  15. The microstructure and wettability of the TiO{sub x} films synthesized by reactive DC magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Lin Zeng [School of Mechanical Engineering and Automation, Northeastern University, Shenyang 110004 (China); State Key Laboratory of Plastic Forming Simulation and Die and Mould Technology Wuhan, Hubei 430074 (China)], E-mail: linzengsy@gmail.com; Liu Kun; Zhang Yichen; Yue Xiangji; Song Guiqiu [School of Mechanical Engineering and Automation, Northeastern University, Shenyang 110004 (China); Ba Dechun [School of Mechanical Engineering and Automation, Northeastern University, Shenyang 110004 (China)], E-mail: dechunba@yahoo.com

    2009-01-25

    Different chemical state of titanium oxide films were deposited on commercially pure Ti (CP Ti) by reactive DC magnetron sputtering under different oxygen flow rates to examine a possibility of their applications to endovascular stents. The chemical composition and crystal structure of the obtained films were analyzed by XPS and XRD, respectively. In dependence on the deposition parameters employed, the obtained films demonstrated different mixture of anatase TiO{sub 2}, Ti{sub 2}O{sub 3}, TiO and Ti. The wettability of the films was measured by the water contact angle variation. By formation of titanium oxide film on CP Ti, contact angle was decreased. In order to modify and control the surface wettability, the resultant TiO{sub x} films were etched subsequently by different plasma. The wettability was influenced by etched process according to the decreased contact angle values of etched TiO{sub x} film. Furthermore, TiO{sub x} films became highly hydrophilic by ultraviolet (UV) irradiation, and returned to the initial relatively hydrophobic state by visible-light (VIS) irradiation. The wettability of the TiO{sub x} film was enabled to convert between hydrophilic and hydrophobic reversibly by alternative UV and VIS irradiation. By adjusting deposition parameter and further modification process, the wettability of the TiO{sub x} films can be changed freely in the range of 0-90 deg.

  16. Preparation of p-type transparent conducting tin-antimony oxide thin films by DC reactive magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Zhenguo [College of Electronic Information, Hangzhou Dianzi University, Hangzhou (China); State Key Laboratory for Silicon Materials, Zhejiang University, Hangzhou (China); Xi, Junhua; Huo, Lijuan; Zhao, Yi [State Key Laboratory for Silicon Materials, Zhejiang University, Hangzhou (China)

    2008-07-01

    P-type transparent conducting tin-antimony oxide (TAO) films were successfully prepared by DC reactive magnetron sputtering followed by post annealing in the air. Structural, optical and electrical properties of the TAO films were investigated. X-ray diffraction studies showed that the films are polycrystalline with orthorhombic structure of Sb{sub 2}O{sub 4}. UV-Visible absorption and transmittance spectra showed that the optical band-gap of the TAO films is about 3.90 eV, and the overall transmittance is higher than 85% in the visible region. Hall effect measurement indicated that the Sn/Sb ratio is a critical parameter to get p-type conducting TAO films. It was found that 0.19

  17. Incorporation of N in TiO{sub 2} films grown by DC-reactive magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Serio, S. [CEFITEC, Departamento de Fisica, Faculdade de Ciencias e Tecnologia da Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Melo Jorge, M.E. [CCMM, Departamento de Quimica e Bioquimica, Faculdade de Ciencias da Universidade de Lisboa, Campo Grande C8, 1749-016 Lisboa (Portugal); Nunes, Y. [CEFITEC, Departamento de Fisica, Faculdade de Ciencias e Tecnologia da Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Barradas, N.P. [Instituto Tecnologico e Nuclear and CFNUL, E.N. 10, Sacavem 2686-953 (Portugal); Alves, E., E-mail: ealves@itn.pt [Instituto Tecnologico e Nuclear and CFNUL, E.N. 10, Sacavem 2686-953 (Portugal); Munnik, F. [Helmholtz-Zentrum Dresden-Rossendorf (Germany)

    2012-02-15

    Photocatalytic properties of TiO{sub 2} are expected to play an important role on emerging technologies based on OH radicals to destroy harmful nonbiodegradable organic and inorganic contaminants in water. The drawback is the wide band gap of TiO{sub 2} (3.2 eV) limiting its use to the UV part of electromagnetic spectrum under sunlight. Therefore, modifications of TiO{sub 2} are needed to tune the gap in order to allow an efficient use of the entire solar spectrum. One possibility is N-doping of TiO{sub 2} to make the photocatalytic activity possible under visible light and more suitable for water treatment. In our study nitrogen-doped TiO{sub 2} (TiO{sub 2-x}N{sub x}) films were deposited by DC-reactive magnetron sputtering using a dual-magnetron co-deposition apparatus on unheated glass and silicon substrates using a pure titanium target. The depth profile of nitrogen was measured with heavy ion elastic recoil detection analysis combined with Rutherford backscattering spectrometry (RBS) and correlated with the optical and structural properties obtained by UV-VIS spectroscopy and X-ray diffraction (XRD).

  18. Verification and Analysis of Implementing Virtual Electric Devices in Circuit Simulation of Pulsed DC Electrical Devices in the NI MULTISIM 10.1 Environment

    Directory of Open Access Journals (Sweden)

    V. A. Solov'ev

    2015-01-01

    Full Text Available The paper presents the analysis results of the implementation potential and evaluation of the virtual electric devices reliability when conducting circuit simulation of pulsed DC electrical devices in the NI Multisim 10.1environment. It analyses metrological properties of electric measuring devices and sensors of the NI Multisim 10.1environment. To calculate the reliable parameters of periodic non-sinusoidal electrical values based on their physical feasibility the mathematical expressions have been defined.To verify the virtual electric devices a circuit model of the power section of buck DC converter with enabled devices under consideration at its input and output is used as a consumer of pulse current of trapezoidal or triangular form. It is used as an example to show a technique to verify readings of virtual electric measuring devices in the NI Multisim 10.1environment.It is found that when simulating the pulsed DC electric devices to measure average and RMS voltage supply and current consumption values it is advisable to use the probe. Electric device power consumption read from the virtual power meter is equal to its average value, and its displayed power factor is inversely proportional to the input current form factor. To determine the RMS pulsed DC current by ammeter and multi-meter it is necessary to measure current by these devices in DC and AC modes, and then determine the RMS value of measurement results.Virtual electric devices verification has proved the possibility of their application to determine the energy performance of transistor converters for various purposes in the circuit simulation in the NI 10.1 Multisim environment, thus saving time of their designing.

  19. Gas Sensing Properties of Metal Doped WO3 Thin Film Sensors Prepared by Pulsed Laser Deposition and DC Sputtering Process

    Science.gov (United States)

    Bhuiyan, Md. Mosharraf Hossain; Ueda, Tsuyoshi; Ikegami, Tomoaki; Ebihara, Kenji

    2006-10-01

    Tungsten trioxide (WO3) thin films gas sensors were prepared by the KrF excimer pulsed laser deposition (PLD) method. The films were prepared on the quartz glass, silicon and also on the Al2O3 sensor substrates with platinum interdigitated electrodes. The effect of doping of the platinum (Pt), palladium (Pd) or gold (Au) on the WO3 thin film was also investigated. These metals were doped to the WO3 thin film by the DC sputtering process during the PLD. The substrate temperature and the oxygen pressure were 400 °C and 100 mTorr, respectively, during the deposition. The films were characterized by atomic force microscopy (AFM) and X-ray diffraction (XRD). The sensitivity of the prepared sensors to 60 ppm NO gas was examined using the two terminal resistance method in a chamber at atmospheric pressure and operating temperatures of 25-350 °C. The sensitivity of the WO3 thin films doped with Pt, Pd, or Au was found to be higher than that of the undoped WO3 thin film.

  20. Transmission of reactive pulsed laser deposited VO{sub 2} films in the THz domain

    Energy Technology Data Exchange (ETDEWEB)

    Émond, Nicolas; Hendaoui, Ali; Ibrahim, Akram; Al-Naib, Ibraheem; Ozaki, Tsuneyuki; Chaker, Mohamed, E-mail: chaker@emt.inrs.ca

    2016-08-30

    Highlights: • Synthesis of vanadium dioxide (VO{sub 2}) thin films as a function of oxygen pressure (2–25 mTorr) using Reactive Pulsed Laser Deposition (RPLD). • Characterization of RPLD-grown VO{sub 2} thin films in the THz frequency range. • THz switches and/or sensors require VO{sub 2} films deposited at low oxygen pressure (i.e. low transition temperature, large amplitude contrast of THz transmission, narrow hysteresis width). • THz optical memory applications require VO{sub 2} films deposited at high oxygen pressure (broad hysteresis width). - Abstract: This work reports on the characteristics of the insulator-to-metal transition (IMT) of reactive pulsed laser deposited vanadium dioxide (VO{sub 2}) films in the terahertz (THz) frequency range, namely the transition temperature T{sub IMT}, the amplitude contrast of the THz transmission over the IMT ΔA, the transition sharpness ΔT and the hysteresis width ΔH. XRD analysis shows the sole formation of VO{sub 2} monoclinic structure with an enhancement of (011) preferential orientation when varying the O{sub 2} pressure (P{sub O2}) during the deposition process from 2 to 25 mTorr. THz transmission measurements as a function of temperature reveal that VO{sub 2} films obtained at low P{sub O2} exhibit low T{sub IMT}, large ΔA, and narrow ΔH. Increasing P{sub O2} results in VO{sub 2} films with higher T{sub IMT}, smaller ΔA, broader ΔH and asymmetric hysteresis loop. The good control of the VO{sub 2} IMT features in the THz domain could be further exploited for the development of advanced smart devices, such as ultrafast switches, modulators, memories and sensors.

  1. Pulsed reactivity measurements of large 235U--Al castings in H2O

    International Nuclear Information System (INIS)

    Pellarin, D.J.; Jarriel, J.L.

    1977-01-01

    The safe storage and handling of large 235 U-Al castings at the Savannah River Plant are assured by limiting the number of fuel pieces and their spacing such that the k/sub eff/ calculated by KENO-IV with Hansen-Roach cross sections does not exceed some conservative limit with complete, accidental water immersion. For economic reasons, the conservative limit on the calculated k/sub eff/ is generally chosen as high as possible consistent with an accurate knowledge of the margin of error in the k/sub eff/ calculation. The margin of error for arrays of large, hollow cylinders of highly enriched 235 U-Al alloy fuel in H 2 O is presented. The subcritical reactivities were derived from pulsed neutron measurements. The measurements are extended to castings with 17.39 kg 235 U/m, the pulsed experiments are more accurately analyzed by the αv -1 method, and measurements for both 7-assembly hexagonal and 2 x 3 square pitch lattices are compared with KENO-IV calculations

  2. Structural and optical properties of surface-hydrogenated silicon nanocrystallites prepared by reactive pulsed laser ablation

    International Nuclear Information System (INIS)

    Makino, Toshiharu; Inada, Mitsuru; Umezu, Ikurou; Sugimura, Akira

    2005-01-01

    Pulsed laser ablation (PLA) in an inert background gas is a promising technique for preparing Si nanoparticles. Although an inert gas is appropriate for preparing pure material, a reactive background gas can be used to prepare compound nanoparticles. We performed PLA in hydrogen gas to prepare hydrogenated silicon nanoparticles. The mean diameter of the primary particles measured using transmission electron microscopy was approximately 5 nm. The hydrogen content in the deposits was very high and estimated to be about 20%. The infrared absorption corresponding to Si-H n (n = 1, 2, 3) bonds on the surface were observed at around 2100 cm -1 . The Raman scattering peak corresponding to crystalline Si was observed, and that corresponding to amorphous Si was negligibly small. These results indicate that the Si nanoparticles were not an alloy of Si and hydrogen but Si nanocrystallite (nc-Si) covered by hydrogen or hydrogenated amorphous silicon. This means that PLA in reactive H 2 gas is a promising technique for preparing surface passivated nc-Si. The deposition mechanism and optical properties of the surface passivated silicon nanocrystallites are discussed

  3. Models of WO x films growth during pulsed laser deposition at elevated pressures of reactive gas

    Science.gov (United States)

    Gnedovets, A. G.; Fominski, V. Y.; Nevolin, V. N.; Romanov, R. I.; Fominski, D. V.; Soloviev, A. A.

    2017-12-01

    The films of tungsten oxides were prepared by pulsed laser ablation of W target in a reactive gas atmosphere (air of laboratory humidity). Optical analysis and ion signal measurements for the laser plume allowed to recognise a threshold gas pressure that suppresses the deposition of non-scattered atomic flux from the plume. When the pressure exceeds about 40 Pa, the films grow due to the deposition of species that could be formed in collisions of W atoms with reactive molecules (e.g., O2). Kinetic Monte Carlo method was used for modelling film growth. Comparison of the model structures with the experimentally prepared films has shown that the growth mechanism of ballistic deposition at a pressure of 40 Pa could be changed on the diffusion limited aggregation at a pressure of ~100 Pa. Thus, a cauliflower structure of the film transformed to a web-like structure. For good correlation of experimental and model structures of WO x , a dimension of structural elements in the model should coincide with W-O cluster size.

  4. Assessment of macrovascular endothelial function using pulse wave analysis and its association with microvascular reactivity in healthy subjects.

    Science.gov (United States)

    Ibrahim, N N I N; Rasool, A H G

    2017-08-01

    Pulse wave analysis (PWA) and laser Doppler fluximetry (LDF) are non-invasive methods of assessing macrovascular endothelial function and microvascular reactivity respectively. The aim of this study was to assess the correlation between macrovascular endothelial function assessed by PWA and microvascular reactivity assessed by LDF. 297 healthy and non-smoking subjects (159 females, mean age (±SD) 23.56 ± 4.54 years) underwent microvascular reactivity assessment using LDF followed by macrovascular endothelial function assessments using PWA. Pearson's correlation showed no correlation between macrovascular endothelial function and microvascular reactivity (r = -0.10, P = 0.12). There was no significant correlation between macrovascular endothelial function assessed by PWA and microvascular reactivity assessed by LDF in healthy subjects. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  5. Room temperature H2S gas sensing property of indium oxide thin films obtained by pulsed D.C. magnetron sputtering

    International Nuclear Information System (INIS)

    Nisha, R.; Madhusoodanan, K.N.; Karthikeyan, Sreejith; Hill, Arthur E.; Pilkington, Richard D.

    2013-01-01

    Indium oxide thin films were prepared by pulsed dc magnetron sputtering technique with no substrate heating. X-ray diffraction was used to investigate the structural properties and AFM was used to study the surface morphology gas sensing performance were conducted using a static gas sensing system. Room temperature gas sensing performance was conducted in range of 17 to 286 ppm. The sensitivity, response and recovery time of the sensor was also determined. (author)

  6. DC-pulse atmospheric-pressure plasma jet and dielectric barrier discharge surface treatments on fluorine-doped tin oxide for perovskite solar cell application

    Science.gov (United States)

    Tsai, Jui-Hsuan; Cheng, I.-Chun; Hsu, Cheng-Che; Chen, Jian-Zhang

    2018-01-01

    Nitrogen DC-pulse atmospheric-pressure plasma jet (APPJ) and nitrogen dielectric barrier discharge (DBD) were applied to pre-treat fluorine-doped tin oxide (FTO) glass substrates for perovskite solar cells (PSCs). Nitrogen DC-pulse APPJ treatment (substrate temperature: ~400 °C) for 10 s can effectively increase the wettability, whereas nitrogen DBD treatment (maximum substrate temperature: ~140 °C) achieved limited improvement in wettability even with increased treatment time of 60 s. XPS results indicate that 10 s APPJ, 60 s DBD, and 15 min UV-ozone treatment of FTO glass substrates can decontaminate the surface. A PSC fabricated on APPJ-treated FTO showed the highest power conversion efficiency (PCE) of 14.90%; by contrast, a PSC with nitrogen DBD-treated FTO shows slightly lower PCE of 12.57% which was comparable to that of a PSC on FTO treated by a 15 min UV-ozone process. Both nitrogen DC-pulse APPJ and nitrogen DBD can decontaminate FTO substrates and can be applied for the substrate cleaning step of PSC.

  7. Diagnostics of atmospheric-pressure pulsed-dc discharge with metal and liquid anodes by multiple laser-aided methods

    Science.gov (United States)

    Urabe, Keiichiro; Shirai, Naoki; Tomita, Kentaro; Akiyama, Tsuyoshi; Murakami, Tomoyuki

    2016-08-01

    The density and temperature of electrons and key heavy particles were measured in an atmospheric-pressure pulsed-dc helium discharge plasma with a nitrogen molecular impurity generated using system with a liquid or metal anode and a metal cathode. To obtain these parameters, we conducted experiments using several laser-aided methods: Thomson scattering spectroscopy to obtain the spatial profiles of electron density and temperature, Raman scattering spectroscopy to obtain the neutral molecular nitrogen rotational temperature, phase-modulated dispersion interferometry to determine the temporal variation of the electron density, and time-resolved laser absorption spectroscopy to analyze the temporal variation of the helium metastable atom density. The electron density and temperature measured by Thomson scattering varied from 2.4  ×  1014 cm-3 and 1.8 eV at the center of the discharge to 0.8  ×  1014 cm-3 and 1.5 eV near the outer edge of the plasma in the case of the metal anode, respectively. The electron density obtained with the liquid anode was approximately 20% smaller than that obtained with the metal anode, while the electron temperature was not significantly affected by the anode material. The molecular nitrogen rotational temperatures were 1200 K with the metal anode and 1650 K with the liquid anode at the outer edge of the plasma column. The density of helium metastable atoms decreased by a factor of two when using the liquid anode.

  8. Studies on the reactive pulsed-magnetron sputtering of ITO from metallic targets; Untersuchungen zum reaktiven Pulsmagnetronsputtern von ITO von metallischen Targets

    Energy Technology Data Exchange (ETDEWEB)

    Gnehr, W.M.

    2006-06-15

    The thesis deals with a reactive sputter process for the deposition of ITO- films. In contrast to the usual technique, the sputter targets consists of indium-tin-alloy instead of ceramic ITO. All experiments were conducted on an inline coater with 600 mm target-width. The process is stabilized by a control loop based on optical emission detection. The experiments prove, that this control loop guarantees a long term stability of the outcomes of the coating process.Process parameters, that are crucial for the optical and electrical properties of the deposited thin films are identified and studied. Among them are the flow of oxygen and the substrate temperature but also less obvious parameters such as the distance between target and substrate.Througout the work the focus is on the film deposition with pulsed plasmas. Novel bipolar DC pulse- and pulse package generators are employed for the deposition.In order to shed some light onto the influence of certain pulse parameters on the outcome of a particular coating process, a Monte-Carlo-Simulation of the particle flow in pulsed plasmas is developed. This simulation yields the distribution of particles and their respective energies on deliberately placed planes in the process chamber. Particles under investigation are both sputtered species and neutral sputter gas atoms reflected at the target. The results of this simulation provide an explanation for the influence of certain pulse parameters on the outcome of the coating process. The further investigations deal with the influence of the construction of the process chamber on the coating process. For this purpose, locally resolved optical spectra are recorded. In order to analyse these spectra, a novel connected fit algorithm is developed.This algorithm yields the distribution of certain fitparameters on the substrate. Provided the most complex of the discussed parametrizations of the dielectric function are used, these can be crucial properties such as the carrier

  9. Influence of deposition parameters on the optical and structural properties of TiO/sub 2/ films produced by reactive dc plasmatron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Schiller, S; Beister, G; Sieber, W; Schirmer, G; Hacker, E

    1981-09-11

    We investigated the variations in the structure and optical properties of TiO/sub 2/ films produced by reactive d.c. plasmatron sputtering with the most important deposition parameters. Over a wide range, the phase composition (ratio of rutile to anatase) and the grain size of the TiO/sub 2/ films can be influenced in a controlled manner by variations in the substrate temperature and the oxygen partial pressure. Because of their high refractive index and low light-scattering losses, plasmatron-sputtered TiO/sub 2/ films are of great interest in the field of optical interference coatings, e.g. for dielectric multilayer stacks.

  10. Study on the clinical application of pulsed DC magnetic technology for tracking of intraoperative head motion during frameless stereotaxy

    Directory of Open Access Journals (Sweden)

    Stendel Rüdiger

    2006-04-01

    Full Text Available Abstract Background Tracking of post-registration head motion is one of the major problems in frameless stereotaxy. Various attempts in detecting and compensating for this phenomenon rely on a fixed reference device rigidly attached to the patient's head. However, most of such reference tools are either based on an invasive fixation technique or have physical limitations which allow mobility of the head only in a restricted range of motion after completion of the registration procedure. Methods A new sensor-based reference tool, the so-called Dynamic Reference Frame (DRF which is designed to allow an unrestricted, 360° range of motion for the intraoperative use in pulsed DC magnetic navigation was tested in 40 patients. Different methods of non-invasive attachment dependent on the clinical need and type of procedure, as well as the resulting accuracies in the clinical application have been analyzed. Results Apart from conventional, completely rigid immobilization of the head (type A, four additional modes of head fixation and attachment of the DRF were distinguished on clinical grounds: type B1 = pin fixation plus oral DRF attachment; type B2 = pin fixation plus retroauricular DRF attachment; type C1 = free head positioning with oral DRF; and type C2 = free head positioning with retroauricular DRF. Mean fiducial registration errors (FRE were as follows: type A interventions = 1.51 mm, B1 = 1.56 mm, B2 = 1.54 mm, C1 = 1.73 mm, and C2 = 1.75 mm. The mean position errors determined at the end of the intervention as a measure of application accuracy were: 1.45 mm in type A interventions, 1.26 mm in type B1, 1.44 mm in type B2, 1.86 mm in type C1, and 1.68 mm in type C2. Conclusion Rigid head immobilization guarantees most reliable accuracy in various types of frameless stereotaxy. The use of an additional DRF, however, increases the application scope of frameless stereotaxy to include e.g. procedures in which rigid pin fixation of the cranium is

  11. Effect of the diameter and depth of pinholes on surface characteristics in the DC pulse plasma nitriding process

    International Nuclear Information System (INIS)

    Calahonra, M.C.G; Egidi, D.A; Svoboda, H; Corengia, P

    2006-01-01

    The ion nitriding treatment is a process widely used in steel alloys to improve the material's properties; such as surface hardness, resistance to wear, fatigue life and resistance to corrosion. But geometric changes in the components can produce during the nitriding process different effects on the behavior of the plasma, such as local variations in the electric field, an empty cathode effect, etc. These in turn can affect among other factors the local temperature and therefore the kinetics of the process, generating variations in the compound layer thicknesses and zone of diffusion, and micro-hardness profile. These heterogeneities limit the effectiveness of the plasma nitriding process, where control and duplication of the surface modification are most important. This work aims to study the effect of the geometry of the pieces treated with ionic nitriding, especially the effect of the orifices. An understanding of the operating mechanisms is sought in order to predict the development of the compound layer and zone of diffusion inside the pinholes. A series of orifices with different diameters and depths were machine made in AISI 4140 quenched and tempered cylindrical steel test pieces. The diameters analyzed were 2, 4, 6, 10 and 12 mm, while the depths studied were 3, 8 and 15 mm, resulting in 15 different configurations. The samples were nitrided by DC-pulse plasma in an industrial reactor, using a mixture of 75% H 2 - 25% N 2 , during 15 hours at a temperature of 500 o C. The nitrided test pieces were characterized with transverse sections using optic and scanning electron microscopy and Vickers micro-hardness profiles, measuring the thicknesses of white layer and zone of diffusion on the wall and base of the orifices. The results show that the sizes of the pinholes made in AISI 4140 steel greatly influence the uniformity and continuity of the compound layers and zones of diffusion. 'Critical diameters' for pinholes were also defined, underneath which the

  12. Nanosecond pulsed electric fields (nsPEFs) low cost generator design using power MOSFET and Cockcroft-Walton multiplier circuit as high voltage DC source

    International Nuclear Information System (INIS)

    Sulaeman, M. Y.; Widita, R.

    2014-01-01

    Purpose: Non-ionizing radiation therapy for cancer using pulsed electric field with high intensity field has become an interesting field new research topic. A new method using nanosecond pulsed electric fields (nsPEFs) offers a novel means to treat cancer. Not like the conventional electroporation, nsPEFs able to create nanopores in all membranes of the cell, including membrane in cell organelles, like mitochondria and nucleus. NsPEFs will promote cell death in several cell types, including cancer cell by apoptosis mechanism. NsPEFs will use pulse with intensity of electric field higher than conventional electroporation, between 20–100 kV/cm and with shorter duration of pulse than conventional electroporation. NsPEFs requires a generator to produce high voltage pulse and to achieve high intensity electric field with proper pulse width. However, manufacturing cost for creating generator that generates a high voltage with short duration for nsPEFs purposes is highly expensive. Hence, the aim of this research is to obtain the low cost generator design that is able to produce a high voltage pulse with nanosecond width and will be used for nsPEFs purposes. Method: Cockcroft-Walton multiplier circuit will boost the input of 220 volt AC into high voltage DC around 1500 volt and it will be combined by a series of power MOSFET as a fast switch to obtain a high voltage with nanosecond pulse width. The motivation using Cockcroft-Walton multiplier is to acquire a low-cost high voltage DC generator; it will use capacitors and diodes arranged like a step. Power MOSFET connected in series is used as voltage divider to share the high voltage in order not to damage them. Results: This design is expected to acquire a low-cost generator that can achieve the high voltage pulse in amount of −1.5 kV with falltime 3 ns and risetime 15 ns into a 50Ω load that will be used for nsPEFs purposes. Further detailed on the circuit design will be explained at presentation

  13. Theoretical models for electron conduction in polymer systems—I. Macroscopic calculations of d.c. transient conductivity after pulse irradiation

    Science.gov (United States)

    Bartczak, Witold M.; Kroh, Jerzy

    The simulation of the transient d.c. conductivity in a quasi one-dimensional system of charges produced by a pulse of ionizing radiation in a solid sample has been performed. The simulation is based on the macroscopic conductivity equations and can provide physical insight into d.c. conductivity measurements, particularly for the case of transient currents in samples with internal space charge. We consider the system of mobile (negative) and immobile (positive) charges produced by a pulse of ionizing radiation in the sample under a fixed external voltage V0. The presence of space charge results in an electric field which is a function of both the spatial and the time variable: E( z, t). Given the space charge density, the electric field can be calculated from the Poisson equation. However, for an arbitrary space charge distribution, the corresponding equations can only be solved numerically. The two non-trivial cases for which approximate analytical solutions can be provided are: (i) The density of the current carriers n( z, t) is negligible in comparison with the density of immobile space charge N( z). A general analytical solution has been found for this case using Green's functions. The solutions for two cases, viz. the homogeneous distribution of space charge N( z) = N, and the non-homogeneous exponential distribution N( z) = A exp(- Bz), have been separately discussed. (ii) The space charge created in the pulse without any space charge present prior to the irradiation.

  14. Measurement of the C{sub 2}H{sub 2} destruction kinetics by infrared laser absorption spectroscopy in a pulsed low pressure dc discharge

    Energy Technology Data Exchange (ETDEWEB)

    Rousseau, A [LPTP, Ecole Polytechnique, CNRS, Route de Saclay, 91 128 Palaiseau Cedex (France); Guaitella, O [LPTP, Ecole Polytechnique, CNRS, Route de Saclay, 91 128 Palaiseau Cedex (France); Gatilova, L [LPTP, Ecole Polytechnique, CNRS, Route de Saclay, 91 128 Palaiseau Cedex (France); Hannemann, M [INP-Greifswald, Friedrich-Ludwig-Jahn-Str. 19, 17489 Greifswald (Germany); Roepcke, J [INP-Greifswald, Friedrich-Ludwig-Jahn-Str. 19, 17489 Greifswald (Germany)

    2007-04-07

    The kinetics of destruction of C{sub 2}H{sub 2} is investigated in a low pressure pulsed dc discharge in dry air. Tuneable diode laser absorption spectroscopy in the mid-infrared region (1350 cm{sup -1}) has been used to measure the influence of (i) the pulse duration (ii) the pulse repetition rate and (iii) the pulse current on the C{sub 2}H{sub 2} concentration in situ the discharge tube. First, it is shown that in the plasma region under flow conditions the time averaged concentration of C{sub 2}H{sub 2} depends only on the time averaged discharge current. Second, time resolved measurements have been performed in a closed reactor, i.e. under static conditions. A simple kinetic modelling of the pulsed discharge leads to a good agreement with the experimental results and shows that the oxidation rate of C{sub 2}H{sub 2} is mainly controlled by the time averaged concentration of O atoms. Finally, the influence of porous TiO{sub 2} photocatalyst on the C{sub 2}H{sub 2} oxidation rate is reported.

  15. Measurement of the C2H2 destruction kinetics by infrared laser absorption spectroscopy in a pulsed low pressure dc discharge

    International Nuclear Information System (INIS)

    Rousseau, A; Guaitella, O; Gatilova, L; Hannemann, M; Roepcke, J

    2007-01-01

    The kinetics of destruction of C 2 H 2 is investigated in a low pressure pulsed dc discharge in dry air. Tuneable diode laser absorption spectroscopy in the mid-infrared region (1350 cm -1 ) has been used to measure the influence of (i) the pulse duration (ii) the pulse repetition rate and (iii) the pulse current on the C 2 H 2 concentration in situ the discharge tube. First, it is shown that in the plasma region under flow conditions the time averaged concentration of C 2 H 2 depends only on the time averaged discharge current. Second, time resolved measurements have been performed in a closed reactor, i.e. under static conditions. A simple kinetic modelling of the pulsed discharge leads to a good agreement with the experimental results and shows that the oxidation rate of C 2 H 2 is mainly controlled by the time averaged concentration of O atoms. Finally, the influence of porous TiO 2 photocatalyst on the C 2 H 2 oxidation rate is reported

  16. Control of Reactive Species Generated by Low-frequency Biased Nanosecond Pulse Discharge in Atmospheric Pressure Plasma Effluent

    Science.gov (United States)

    Takashima, Keisuke; Kaneko, Toshiro

    2016-09-01

    The control of hydroxyl radical and the other gas phase species generation in the ejected gas through air plasma (air plasma effluent) has been experimentally studied, which is a key to extend the range of plasma treatment. Nanosecond pulse discharge is known to produce high reduced electric field (E/N) discharge that leads to efficient generation of the reactive species than conventional low frequency discharge, while the charge-voltage cycle in the low frequency discharge is known to be well-controlled. In this study, the nanosecond pulse discharge biased with AC low frequency high voltage is used to take advantages of these discharges, which allows us to modulate the reactive species composition in the air plasma effluent. The utilization of the gas-liquid interface and the liquid phase chemical reactions between the modulated long-lived reactive species delivered from the air plasma effluent could realize efficient liquid phase chemical reactions leading to short-lived reactive species production far from the air plasma, which is crucial for some plasma agricultural applications.

  17. Monte Carlo Simulations of High-speed, Time-gated MCP-based X-ray Detectors: Saturation Effects in DC and Pulsed Modes and Detector Dynamic Range

    International Nuclear Information System (INIS)

    Kruschwitz, Craig; Ming Wu; Moy, Ken; Rochau, Greg

    2008-01-01

    We present here results of continued efforts to understand the performance of microchannel plate (MCP)-based, high-speed, gated, x-ray detectors. This work involves the continued improvement of a Monte Carlo simulation code to describe MCP performance coupled with experimental efforts to better characterize such detectors. Our goal is a quantitative description of MCP saturation behavior in both static and pulsed modes. We have developed a new model of charge buildup on the walls of the MCP channels and measured its effect on MCP gain. The results are compared to experimental data obtained with a short-pulse, high-intensity ultraviolet laser; these results clearly demonstrate MCP saturation behavior in both DC and pulsed modes. The simulations compare favorably to the experimental results. The dynamic range of the detectors in pulsed operation is of particular interest when fielding an MCP-based camera. By adjusting the laser flux we study the linear range of the camera. These results, too, are compared to our simulations

  18. Ga-doped ZnO films deposited with varying sputtering powers and substrate temperatures by pulsed DC magnetron sputtering and their property improvement potentials

    International Nuclear Information System (INIS)

    Lee, Sanghun; Cheon, Dongkeun; Kim, Won-Jeong; Ham, Moon-Ho; Lee, Woong

    2012-01-01

    Ga-doped ZnO (GZO) transparent conductive oxide (TCO) films were deposited on glass substrates by pulsed DC magnetron sputtering with varying sputtering power and substrate temperature while fixing the Ga concentration in the sputtering target. The application of higher sputtering power by pulsed DC magnetrons sputtering at a moderate temperature of 423 K results in increased carrier concentration and mobility which accompanied improved doping efficiency and crystalline quality. Substrate temperature was found to be the more dominant parameter in controlling the electrical properties and crystallinity, while the sputtering power played synergistic auxiliary roles. Electrical and optical properties of the GZO TCO films fulfilled requirements for transparent electrodes, despite relatively low substrate temperature (423 K) and small thickness (100 nm). In an attempt to improve the electrical properties of the GZO films by hydrogen-treatment, it was observed that the substitutional Ga plays the complex role of carrier generator as donor and carrier suppressor deactivating the oxygen vacancy simultaneously, which would complicate the property improvement by increasing doping efficiency.

  19. Modified DLC coatings prepared in a large-scale reactor by dual microwave/pulsed-DC plasma-activated chemical vapour deposition

    International Nuclear Information System (INIS)

    Corbella, C.; Bialuch, I.; Kleinschmidt, M.; Bewilogua, K.

    2008-01-01

    Diamond-Like Carbon (DLC) films find abundant applications as hard and protective coatings due to their excellent mechanical and tribological performances. The addition of new elements to the amorphous DLC matrix tunes the properties of this material, leading to an extension of its scope of applications. In order to scale up their production to a large plasma reactor, DLC films modified by silicon and oxygen additions have been grown in an industrial plant of 1m 3 by means of pulsed-DC plasma-activated chemical vapour deposition (PACVD). The use of an additional microwave (MW) source has intensified the glow discharge, partly by electron cyclotron resonance (ECR), accelerating therefore the deposition process. Hence, acetylene, tetramethylsilane (TMS) and hexamethyldisiloxane (HMDSO) constituted the respective gas precursors for the deposition of a-C:H (DLC), a-C:H:Si and a-C:H:Si:O films by dual MW/pulsed-DC PACVD. This work presents systematic studies of the deposition rate, hardness, adhesion, abrasive wear and water contact angle aimed to optimize the technological parameters of deposition: gas pressure, relative gas flow of the monomers and input power. This study has been completed with measures of the atomic composition of the samples. Deposition rates around 1 μm/h, typical for standard processes held in the large reactor, were increased about by a factor 10 when the ionization source has been operated in ECR mode

  20. Effects of gamma irradiations on reactive pulsed laser deposited vanadium dioxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Madiba, I.G., E-mail: madibagiven@gmail.com [UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, P O Box 392, Pretoria (South Africa); Empa, Swiss Federal Laboratories Materials Science and Technology, CH-8600 Dübendorf (Switzerland); Émond, N.; Chaker, M. [Institut National de la Recherche Scientifique (INRS),1650 Blvd. Lionel-Boulet, Varennes, Québec J3X1S2 (Canada); Thema, F.T. [UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, P O Box 392, Pretoria (South Africa); iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); Tadadjeu, S.I. [iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); Department of Electrical, Electronics and Computer Engineering, French South African Institute of Technology/Cape Peninsula University of Technology, Bellville campus, PO Box 1906, Bellville, 7530 (South Africa); Muller, U.; Zolliker, P. [Empa, Swiss Federal Laboratories Materials Science and Technology, CH-8600 Dübendorf (Switzerland); Braun, A. [ETH Zurich, Swiss Federal Institute of Technology, CH-8057, Zurich (Switzerland); Empa, Swiss Federal Laboratories Materials Science and Technology, CH-8600 Dübendorf (Switzerland); Kotsedi, L. [iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); and others

    2017-07-31

    Highlights: • Synthesis of VO{sub 2} thin films by Reactive pulsed laser deposition has been achieved. • Properties VO{sub 2} remain mainly unaffected when subjected to gamma ray doses similar to those encountered during space missions. • The long range crystal structure of VO{sub 2} remains intact upon irradiation on different doses up to 100 kGy. • XPS reveals a shift from V{sup 4+} to V{sup 5+} oxidation state upon irradiation, due to the frenkel pair formation on the surface. • Irradiated films show the characteristic SMT of VO{sub 2}, although the electrical and optical properties are slightly affected. - Abstract: Vanadium oxide films are considered suitable coatings for various applications such as thermal protective coating of small spacecrafts because of their thermochromic properties. While in outer space, such coating will be exposed to cosmic radiations which include γ-rays. To study the effect of these γ-rays on the coating properties, we have deposited vanadium dioxide (VO{sub 2}) films on silicon substrates and subjected them to extensive γ-irradiations with typical doses encountered in space missions. The prevalent crystallographic phase after irradiation remains the monoclinic VO{sub 2} phase but the films preferential orientation shifts to lower angles due to the presence of disordered regions caused by radiations. Raman spectroscopy measurements also evidences that the VO{sub 2} structure is slightly affected by gamma irradiation. Indeed, increasing the gamma rays dose locally alters the crystalline and electronic structures of the films by modifying the V–V inter-dimer distance, which in turns favours the presence of the VO{sub 2} metallic phase. From the XPS measurements of V2p and O1s core level spectra, an oxidation of vanadium from V{sup 4+} towards V{sup 5+} is revealed. The data also reveal a hydroxylation upon irradiation which is corroborated by the vanishing of a low oxidation state peak near the Fermi energy in the

  1. Effect of N Concentration on Microstructure Evolution of the Nanostructured (Al, Ti, SiN Coatings Prepared by d.c. Reactive Magnetron Sputtering

    Directory of Open Access Journals (Sweden)

    L. Jakab-Farkas

    2009-12-01

    Full Text Available Nanostructured (Al, Ti, SiN thin film coatings were synthesized by d.c. reactive magnetron sputtering, performed in an Ar/N2 gas mixture from a planar rectangular Al:Ti:Si=50:25:25 alloyed target. The mass flow of N2 reactive gas was strictly controlled in sputtering process. Conventional transmission electron microscopy (TEM technique was used for microstructure investigation of the as deposited films. Cross-sectional cuts performed through the deposited films revealed distinct microstructure evolution for different samples. It was found that the variation of the reactive gas amount induced changes in film microstructure. The metallic AlTiSi film exhibited strong columnar growth with a crystalline structure. The addition of a small amount of nitrogen to the process gas leads to a crystallite refinement. Further increase of N concentration resulted in evolution of fine lamellae growth morphology consisting of hainlike pearls in a dendrite, clusters of very fine grains in close crystallographic orientation.

  2. Effect of deposition parameters on properties of ITO films prepared by reactive middle frequency pulsed dual magnetron sputtering

    International Nuclear Information System (INIS)

    Rogozin, A.I.; Vinnichenko, M.V.; Kolitsch, A.; Moeller, W.

    2004-01-01

    ITO layers with low resistivity and high visible transmittance were produced by means of middle frequency reactive dual magnetron sputtering. The influence of base pressure, Ar/O 2 ratio and magnetron pulse duration on the film composition, structure, electrical, and optical properties has been investigated. The deposition rate is proportional to the magnetron operation power at changing pulse duration and constant Ar and O 2 flows. At enhanced O 2 flows an onset of the magnetron target oxidation is discussed as a reason for the decrease of the deposition rate. The presence of water vapor in the residual gas is determined to be a reason for deterioration of resistivity and optical transmittance observed for ITO films produced at a base pressures higher than 5·10 -4 Pa. It is demonstrated that spectroscopic ellipsometry can be used as a noncontact tool to monitor the resistivity of ITO films

  3. Enhancement in dye-sensitized solar cells based on MgO-coated TiO2 electrodes by reactive DC magnetron sputtering

    International Nuclear Information System (INIS)

    Wu Sujuan; Han Hongwei; Tai Qidong; Zhang Jing; Xu Sheng; Zhou Conghua; Yang Ying; Hu Hao; Chen Bolei; Sebo, Bobby; Zhao Xingzhong

    2008-01-01

    A surface modification method was carried out by reactive DC magnetron sputtering to fabricate TiO 2 electrodes coated with insulating MgO for dye-sensitized solar cells. The MgO-coated TiO 2 electrode had been characterized by x-ray photoelectron spectroscopy (XPS), energy-dispersive x-ray spectroscopy (EDX), scanning electron microscopy (SEM), UV-vis spectrophotometer, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The study results revealed that the TiO 2 modification increases dye adsorption, decreases trap states and suppresses interfacial recombination. The effects of sputtering MgO for different times on the performance of DSSCs were investigated. It indicated that sputtering MgO for 3 min on TiO 2 increases all cell parameters, resulting in increasing efficiency from 6.45% to 7.57%

  4. The determination of reactivity at a compact core with low absorption reflector by means of the pulsed neutron method

    International Nuclear Information System (INIS)

    Hecker, R.; Drueke, V.; Ahmad, S.K.; Kacmary, S.; Paul, N.

    1976-09-01

    Pulsed measurements at a compact critical facility with low absorption reflector are described. By a number of such measurements at different points of the system a proper value for the reactivity can be determined, which allows a meaningful comparison with values calculated by static computer codes in spite of the presence of kinetic distortion in the system. A modified area ratio method is developed and applied to the measurements; furthermore a method is shown, which allows to suppress in this systems the kinetic distortion in the fundamental mode by application of special detectors. (orig.) [de

  5. On the estimation of subcritical reactivity by the pulsed α-method

    International Nuclear Information System (INIS)

    Shulepin, V.S.

    1974-01-01

    A technique for calculating the neutron generation time is considered. It is based on the use of only basic (non-conjugate) conditionally critical reactor equations. The formula is drawn to show the relation between the reactivity coefficient Ksub(eff), damping decrement and neutron generation time. Some transformations result in a conditionally critical equation at Ksub(eff) equal to unit, from which the neutron generation time is found that is necessary to measure subcritical reactivity by the α-method

  6. Growth and characterization of polycrystalline Ge{sub 1-x}C{sub x} by reactive pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez, M.P., E-mail: mayrap@fisica.uh.cu [Instituto de Ciencia y Tecnologia de Materiales, Zapata y G, P.O. Box 10400, Universidad de La Habana (Cuba); Farias, M.H.; Castillon, F.F.; Diaz, Jesus A.; Avalos, M. [Centro de Nanociencias y Nanotecnologia, Universidad Nacional Autonoma de Mexico, Km 107 Carretera Tijuana-Ensenada, C.P. 22800 Ensenada, Baja California (Mexico); Ulloa, L. [Universidad de Guadalajara, (CUCEI) Blvd. Marcelino Garcia Barragan 1421, C.P. 44430 Guadalajara, Jalisco (Mexico); Gallegos, J.A.; Yee-Madeiros, H. [Escuela Superior de Fisica y Matematicas-IPN, UP' ALM' , Colonia Lindavista 07738 (Mexico)

    2011-03-15

    Polycrystalline thin films of Ge-C were grown on Si (1 1 1) substrates by means of reactive pulsed laser deposition with methane pressure of 100 mTorr. Effect substrate temperature, T{sub s}, on C incorporation to substitutional sites (x) in Ge{sub 1-x}C{sub x} was investigated systematically by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyzes. The substrate temperatures were ranging from 250 to 400 deg. C. The substitutional C composition x in the films by XRD were estimated using the Vegard's linear law. The maximum value of x calculated by XRD was 0.032 for T{sub s} of 350 deg. C. The position of the C 1s peak at 283.4 eV in the XPS spectrum confirmed the germanium-carbon alloys. XRD measurements indicated that x increased with T{sub s} from 250 deg. C to 350 deg. C. At T{sub s} = 400 deg. C, the estimation of x was lowered. However, the C content calculated by XPS analyzes increased with T{sub s} being more these values than substitutional C composition x. XPS and XRD analyzes demonstrate that the remaining C atoms are incorporated to interstitial sites. The use of the T{sub s} plays important roles in the incorporation of substitutional C and in restraining C-cluster formation in the reactive pulsed laser deposition growth of Ge-C/Si.

  7. Optical, electrical and mechanical properties of the tantalum oxynitride thin films deposited by pulsing reactive gas sputtering

    International Nuclear Information System (INIS)

    Le Dreo, H.; Banakh, O.; Keppner, H.; Steinmann, P.-A.; Briand, D.; Rooij, N.F. de

    2006-01-01

    Thin films of tantalum oxynitride were prepared by reactive magnetron sputtering using a Ta target and N 2 and O 2 as reactive gases. The nitrogen flow was kept constant while the oxygen flow was pulsed periodically. The film composition evolves progressively from TaO 0.25 N 1.51 to TaO 2.42 N 0.25 while increasing the oxygen pulse duty cycle without any abrupt change in the elemental content. The optical transmission spectra of the films deposited on glass show a 'blue shift' of the absorption edge with increasing oxygen content. X-ray diffraction (XRD) patterns of all films exhibit broad peaks typical for nanocrystalline materials. Cross-section film morphology is rather featureless and surface topography is smooth exhibiting very small grains, in agreement with the results obtained by XRD. The optical properties of the films are very sensitive to their chemical composition. All films exhibit semiconducting behaviour with an optical band gap changing from 1.85 to 4.0 eV with increasing oxygen content. In order to evaluate the potential of the tantalum oxynitride films for microelectronic applications some Ta-O-N films were integrated in a MOS structure. The results of the capacitance-voltage measurements of the system Al//Ta-O-N//p-Si are discussed with respect to the chemical composition of the Ta-O-N films

  8. Measurement of deposition rate and ion energy distribution in a pulsed dc magnetron sputtering system using a retarding field analyzer with embedded quartz crystal microbalance.

    Science.gov (United States)

    Sharma, Shailesh; Gahan, David; Scullin, Paul; Doyle, James; Lennon, Jj; Vijayaraghavan, Rajani K; Daniels, Stephen; Hopkins, M B

    2016-04-01

    A compact retarding field analyzer with embedded quartz crystal microbalance has been developed to measure deposition rate, ionized flux fraction, and ion energy distribution arriving at the substrate location. The sensor can be placed on grounded, electrically floating, or radio frequency (rf) biased electrodes. A calibration method is presented to compensate for temperature effects in the quartz crystal. The metal deposition rate, metal ionization fraction, and energy distribution of the ions arriving at the substrate location are investigated in an asymmetric bipolar pulsed dc magnetron sputtering reactor under grounded, floating, and rf biased conditions. The diagnostic presented in this research work does not suffer from complications caused by water cooling arrangements to maintain constant temperature and is an attractive technique for characterizing a thin film deposition system.

  9. Preparation of Ga-doped ZnO films by pulsed dc magnetron sputtering with cylindrical rotating target for thin film solar cell applications

    International Nuclear Information System (INIS)

    Shin, Beom-Ki; Lee, Tae-Il; Park, Ji-Hyeon; Park, Kang-Il; Ahn, Kyung-Jun; Park, Sung-Kee; Lee, Woong; Myoung, Jae-Min

    2011-01-01

    Applicability of Ga-doped ZnO (GZO) films for thin film solar cells (TFSCs) was investigated by preparing GZO films via pulsed dc magnetron sputtering (PDMS) with rotating target. The GZO films showed improved crystallinity and increasing degree of Ga doping with increasing thickness to a limit of 1000 nm. The films also fulfilled requirements for the transparent electrodes of TFSCs in terms of electrical and optical properties. Moreover, the films exhibited good texturing potential based on etching studies with diluted HCl, which yielded an improved light trapping capability without significant degradation in electrical propreties. It is therefore suggested that the surface-textured GZO films prepared via PDMS and etching are promising candidates for indium-free transparent electrodes for TFSCs.

  10. Preparation of Ga-doped ZnO films by pulsed dc magnetron sputtering with cylindrical rotating target for thin film solar cell applications

    Science.gov (United States)

    Shin, Beom-Ki; Lee, Tae-Il; Park, Ji-Hyeon; Park, Kang-Il; Ahn, Kyung-Jun; Park, Sung-Kee; Lee, Woong; Myoung, Jae-Min

    2011-11-01

    Applicability of Ga-doped ZnO (GZO) films for thin film solar cells (TFSCs) was investigated by preparing GZO films via pulsed dc magnetron sputtering (PDMS) with rotating target. The GZO films showed improved crystallinity and increasing degree of Ga doping with increasing thickness to a limit of 1000 nm. The films also fulfilled requirements for the transparent electrodes of TFSCs in terms of electrical and optical properties. Moreover, the films exhibited good texturing potential based on etching studies with diluted HCl, which yielded an improved light trapping capability without significant degradation in electrical propreties. It is therefore suggested that the surface-textured GZO films prepared via PDMS and etching are promising candidates for indium-free transparent electrodes for TFSCs.

  11. Measurement of deposition rate and ion energy distribution in a pulsed dc magnetron sputtering system using a retarding field analyzer with embedded quartz crystal microbalance

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Shailesh, E-mail: shailesh.sharma6@mail.dcu.ie [Dublin City University, Glasnevin, Dublin 9 (Ireland); Impedans Limited, Chase House, City Junction Business Park, Northern Cross, D17 AK63, Dublin 17 (Ireland); Gahan, David, E-mail: david.gahan@impedans.com; Scullin, Paul; Doyle, James; Lennon, Jj; Hopkins, M. B. [Impedans Limited, Chase House, City Junction Business Park, Northern Cross, D17 AK63, Dublin 17 (Ireland); Vijayaraghavan, Rajani K.; Daniels, Stephen [Dublin City University, Glasnevin, Dublin 9 (Ireland)

    2016-04-15

    A compact retarding field analyzer with embedded quartz crystal microbalance has been developed to measure deposition rate, ionized flux fraction, and ion energy distribution arriving at the substrate location. The sensor can be placed on grounded, electrically floating, or radio frequency (rf) biased electrodes. A calibration method is presented to compensate for temperature effects in the quartz crystal. The metal deposition rate, metal ionization fraction, and energy distribution of the ions arriving at the substrate location are investigated in an asymmetric bipolar pulsed dc magnetron sputtering reactor under grounded, floating, and rf biased conditions. The diagnostic presented in this research work does not suffer from complications caused by water cooling arrangements to maintain constant temperature and is an attractive technique for characterizing a thin film deposition system.

  12. Re-activation of degraded nickel cermet anodes - Nano-particle formation via reverse current pulses

    DEFF Research Database (Denmark)

    Hauch, Anne; Marchese, M.; Lanzini, A.

    2018-01-01

    The Ni/yttria-stabilized-zirconia (YSZ) cermet is the most commonly applied fuel electrode for solid oxide cells (SOCs). Loss of Ni/YSZ electrode activity is a key life-time limiting factor of the SOC. Developing means to mitigate this loss of performance or re-activate a fuel electrode is theref......The Ni/yttria-stabilized-zirconia (YSZ) cermet is the most commonly applied fuel electrode for solid oxide cells (SOCs). Loss of Ni/YSZ electrode activity is a key life-time limiting factor of the SOC. Developing means to mitigate this loss of performance or re-activate a fuel electrode...

  13. Reactivity of OH and O– with aqueous methyl viologen studied by pulse radiolysis

    DEFF Research Database (Denmark)

    Solar, Sonja; Solar, Wolfgang; Getoff, Nikola

    1985-01-01

    The behaviour of aqueous MV2+ towards oxidizing radicals (OH and O–) has been investigated in the pH range from 6 to 14 by means of pulse radiolysis. A semi-linear optimization method was applied for resolving the complex reaction mechanism. In the pH range from 6 to 8 the rate constant for attac...

  14. Raman studies of reactive DC-magnetron sputtered thin films of YBaCuO on MgO

    International Nuclear Information System (INIS)

    Sheng, K.C.; Lee, S.J.; Shen, Y.H.; Wang, X.K.; Rippert, E.D.; Van Duyne, R.P.; Ketterson, J.B.; Chang, R.P.H.

    1989-01-01

    Raman spectroscopy was employed to study Y-Ba-Cu-O films prepared by multilayer, reactive sputtering from separate Y, Cu, and Ba 0.5 Cu 0.5 targets. A set of films having the composition Y x Ba 2 Cu y O z with 0.7 c (R=0), ranging from 25 to 90 K was studied with the Raman technique. The correlation between Raman data and critical temperature, T c , was investigated. This technique provides important information concerning the film crystallinity, homogeneity, and impurity content (including other phases) which is useful in judging the quality of high T c superconducting films. We also found that the rapid thermal annealing process is a very efficient way to reduce chemical reactions between the film and the substrate

  15. Effect of plasma immersion on crystallinity of V2O5 film grown by dc reactive sputtering at room temperature

    International Nuclear Information System (INIS)

    Choi, Sun Hee; Kim, Joosun; Yoon, Young Soo

    2005-01-01

    Vanadium oxide thin films were grown at room temperature by direct current reactive sputtering. To investigate the effect of plasma immersion on the crystallinity of as-grown film, we immersed samples in plasma during the deposition process. X-ray diffraction (XRD) measurements show that as-deposited thin films immersed in plasma are crystalline, whereas those not immersed in the plasma are amorphous. Images taken with scanning electron microscopy show that the surface of films exposed to plasma have a different morphology to the surface of films not exposed to plasma. The Li-intercalation feature of as-deposited films immersed in plasma shows the typical behavior of crystalline vanadium oxide; such behavior is unsuitable for the cathode of thin film batteries (TFBs). These results indicate that direct current plasma promotes the growth of crystalline vanadium oxide films

  16. Effect of reactive atmosphere on pulsed laser deposition of hydroxyapatite thin films

    Czech Academy of Sciences Publication Activity Database

    Mroz, W.; Jedynski, M.; Hoffman, J.; Jelínek, Miroslav; Major, B.; Prokopiuk, A.; Szymanski, Z.

    2007-01-01

    Roč. 59, - (2007), s. 720-723 ISSN 1742-6588 Grant - others:PBZ-KBN(PL) 100/TO8/2003 and 0028/TOO/2005/29 Institutional research plan: CEZ:AV0Z10100522 Keywords : PLD * hydroxyapatite * reactive atmosphere * thin layers Subject RIV: BM - Solid Matter Physics ; Magnetism

  17. Combined resonant tank capacitance and pulse frequency modulation control for ZCS-SR inverter-fed high voltage DC power supply

    International Nuclear Information System (INIS)

    Lee, S S; Iqbal, S; Kamarol, M

    2011-01-01

    Conventional pulse frequency modulated (PFM) zero current switching (ZCS) series resonant (SR) inverter fed high voltage dc power supplies have nearly zero switching loss. However, they have limitations of poor controllability at light loads and large output voltage ripple at low switching frequencies. To address these problems, this paper proposes a combined resonant tank capacitance and pulse frequency modulation based control approach. For the realization of the proposed control approach, the tank circuit of the resonant inverter is made up of several resonant capacitors that are switched into or out of the tank circuit by electromechanical switches. The output voltage of the converter is regulated by digitally modulating the resonant tank capacitance and narrowly varying the switching frequency. The proposed control scheme has several features, namely a wide range of controllability even at light loads, less output voltage ripple, and less current stress on the inverter's power switches at light loads. Therefore, the proposed control approach alleviates most of the problems associated with conventional PFM. Experimental results obtained from a scaled down laboratory prototype are presented to verify the effectiveness of the proposed system.

  18. Re-activation of degraded nickel cermet anodes - Nano-particle formation via reverse current pulses

    Science.gov (United States)

    Hauch, A.; Marchese, M.; Lanzini, A.; Graves, C.

    2018-02-01

    The Ni/yttria-stabilized-zirconia (YSZ) cermet is the most commonly applied fuel electrode for solid oxide cells (SOCs). Loss of Ni/YSZ electrode activity is a key life-time limiting factor of the SOC. Developing means to mitigate this loss of performance or re-activate a fuel electrode is therefore important. In this work, we report a series of five tests on state-of-the-art Ni/YSZ-YSZ-CGObarrier-LSC/CGO cells. All cells were deliberately degraded via gas stream impurities in CO2/CO or harsh steam electrolysis operation. The cells were re-activated via a variety of reverse current treatments (RCTs). Via electrochemical impedance spectroscopy, we found that the Ni/YSZ electrode performance could be recovered via RCT, but not via constant fuel cell operation. For optimized RCT, we obtained a lower Ni/YSZ electrode resistance than the initial resistance. E.g. at 700 °C we measured fuel electrode resistance of 180 mΩ cm2, 390 mΩ cm2, and 159 mΩ cm2 before degradation, after degradation and after re-activation via RCT, respectively. Post-test SEM revealed that the RCT led to formation of nano-particles in the fuel electrode. Besides the remarkable improvement, the results also showed that RCTs can weaken Ni/YSZ interfaces and the electrode/electrolyte interface. This indicates that finding an optimum RCT profile is crucial for achieving maximum benefit.

  19. Stress and piezoelectric properties of aluminum nitride thin films deposited onto metal electrodes by pulsed direct current reactive sputtering

    International Nuclear Information System (INIS)

    Dubois, Marc-Alexandre; Muralt, Paul

    2001-01-01

    Polycrystalline aluminum nitride thin films were deposited onto platinum, aluminum, and titanium electrodes by reactive magnetron sputtering in the pulsed direct current mode. The films exhibited all a columnar microstructure and a c-axis texture. The built-in stress and the piezoelectric properties of these films were studied as a function of both the processing conditions and the electrode material. Stress was found to be very much dependent on the growth conditions, and values ranging from strong compression to high tension were observed. The piezoelectric d 33,f coefficient was shown to rely on substrate quality and ionic bombardment: The nucleation surface must be stable with regard to the nitrogen plasma and present a hexagonal symmetry and, on the other hand, enough energy must be delivered to the growing film through ionic bombardment. [copyright] 2001 American Institute of Physics

  20. Effect of substrate type on the electrical and structural properties of TiO2 thin films deposited by reactive DC sputtering

    Science.gov (United States)

    Cheng, Xuemei; Gotoh, Kazuhiro; Nakagawa, Yoshihiko; Usami, Noritaka

    2018-06-01

    Electrical and structural properties of TiO2 thin films deposited at room temperature by reactive DC sputtering have been investigated on three different substrates: high resistivity (>1000 Ω cm) float zone Si(1 1 1), float zone Si(1 0 0) and alkali free glass. As-deposited TiO2 films on glass substrate showed extremely high resistivity of (∼5.5 × 103 Ω cm). In contrast, lower resistivities of ∼2 Ω cm and ∼5 Ω cm were obtained for films on Si(1 1 1) and Si(1 0 0), respectively. The as-deposited films were found to be oxygen-rich amorphous TiO2 for all the substrates as evidenced by X-ray photoemission spectroscopy and X-ray diffraction. Subsequent annealing led to appearance of anatase TiO2 on Si but not on glass. The surface of as-deposited TiO2 on Si was found to be rougher than that on glass. These results suggest that the big difference of electrical resistivity of TiO2 would be related with existence of more anatase nuclei forming on crystalline substrates, which is consistent with the theory of charged clusters that smaller clusters tend to adopt the substrate structure.

  1. Studies on the electrical properties of reactive DC magnetron-sputtered indium-doped silver oxide thin films: The role of oxygen

    Energy Technology Data Exchange (ETDEWEB)

    Subrahmanyam, A [Semiconductor Physics Laboratory, Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India); Barik, Ullash Kumar [Semiconductor Physics Laboratory, Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India)

    2007-03-15

    Indium ({approx}10 at.%)-doped silver oxide (AIO) thin films have been prepared on glass substrates at room temperature (300 K) by reactive DC magnetron sputtering technique using an alloy target made of pure (99.99%) silver and indium (90:10 at.%) metals. The oxygen flow rates have been varied in the range 0.00-3.44 sccm during sputtering. The X-ray diffraction data on these indium-doped silver oxide films show polycrystalline nature. With increasing oxygen flow rate, the carrier concentration, the Hall mobility and the electron mean free path decrease. These films show a very low positive temperature coefficient of resistivity {approx}3.40x10{sup -8} ohm-cm/K. The work function values for these films (measured by Kelvin probe technique) are in the range 4.81-5.07 eV. The high electrical resistivity indicate that the films are in the island state (size effects). Calculations of the partial ionic charge (by Sanderson's theory) show that indium doping in silver oxide thin films enhance the ionicity.

  2. Studies on the electrical properties of reactive DC magnetron-sputtered indium-doped silver oxide thin films: The role of oxygen

    International Nuclear Information System (INIS)

    Subrahmanyam, A.; Barik, Ullash Kumar

    2007-01-01

    Indium (∼10 at.%)-doped silver oxide (AIO) thin films have been prepared on glass substrates at room temperature (300 K) by reactive DC magnetron sputtering technique using an alloy target made of pure (99.99%) silver and indium (90:10 at.%) metals. The oxygen flow rates have been varied in the range 0.00-3.44 sccm during sputtering. The X-ray diffraction data on these indium-doped silver oxide films show polycrystalline nature. With increasing oxygen flow rate, the carrier concentration, the Hall mobility and the electron mean free path decrease. These films show a very low positive temperature coefficient of resistivity ∼3.40x10 -8 ohm-cm/K. The work function values for these films (measured by Kelvin probe technique) are in the range 4.81-5.07 eV. The high electrical resistivity indicate that the films are in the island state (size effects). Calculations of the partial ionic charge (by Sanderson's theory) show that indium doping in silver oxide thin films enhance the ionicity

  3. Hetero-epitaxial growth of TiC films on MgO(001) at 100 °C by DC reactive magnetron sputtering

    International Nuclear Information System (INIS)

    Braic, M.; Zoita, N.C.; Danila, M.; Grigorescu, C.E.A.; Logofatu, C.

    2015-01-01

    Hetero-epitaxial TiC thin films were deposited at 100 °C on MgO(001) by DC reactive magnetron sputtering in a mixture of Ar and CH 4 . The 62 nm thick films were analyzed for elemental composition and chemical bonding by Auger electron spectroscopy, X-ray photoelectron spectroscopy and micro-Raman spectroscopy. The crystallographic structure investigation by high resolution X-ray diffraction revealed that the films consist of two layers: an interface partially strained epilayer with high crystalline quality, and a relaxed layer, formed by columnar grains, maintaining the epitaxial relationship with the substrate. The films presented smooth surfaces (RMS roughness ~ 0.55 nm), with circular equi-sized grains/crystallites, as observed by atomic force microscopy. The Hall measurements in Van der Pauw geometry revealed relatively high resistivity value ~ 620 μΩ cm, ascribed to electron scattering on interfaces, on grain boundaries and on different defects/dislocations. - Highlights: • Hetero-epitaxial TiC 0.84 thin films were grown on MgO(001) at 100 °C by magnetron sputtering. • 62 nm thick films were synthesized by magnetron sputtering, using Ti, Ar and CH 4 . • The film comprises a partially strained interface epilayer and a relaxed top layer. • Both layers preserve the epitaxial relationship with the substrate. • Low RMS surface roughness ~ 0.55 nm and grains with mean lateral size of ~ 38.5 nm were observed

  4. Optical properties and thermal stability of TiAlN/AlON tandem absorber prepared by reactive DC/RF magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Barshilia, Harish C.; Selvakumar, N.; Rajam, K.S. [Surface Engineering Division, National Aerospace Laboratories, Bangalore 560 017 (India); Biswas, A. [Spectroscopy Division, Bhabha Atomic Research Center, Mumbai 400 085 (India)

    2008-11-15

    Spectrally selective TiAlN/AlON tandem absorbers were deposited on copper and stainless steel substrates using a reactive DC/RF magnetron sputtering system. The compositions and thicknesses of the individual component layers were optimized to achieve high absorptance ({alpha}=0.931-0.942) and low emittance ({epsilon}=0.05-0.06) on copper substrate. The experimental spectroscopic ellipsometric data have been fitted with the theoretical models to derive the dispersion of the optical constants (n and k). In order to study the thermal stability of the tandem absorbers, they were subjected to heat treatment (in air and vacuum) for different durations and temperatures. The tandem absorber deposited on Cu substrates exhibited high solar selectivity ({alpha}/{epsilon}) of 0.946/0.07 even after heat treatment in air up to 600 C for 2 h. At 625 C, the solar selectivity decreased significantly on Cu substrates (e.g., {alpha}/{epsilon}=0.924/0.30). The tandem absorber on Cu substrates was also stable in air up to 100 h at 400 C with a solar selectivity of 0.919/0.06. Studies on the accelerated aging tests indicated that the activation energy for the degradation of the tandem absorber is of the order of 100 kJ/mol. (author)

  5. Hetero-epitaxial growth of TiC films on MgO(001) at 100 °C by DC reactive magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Braic, M. [National Institute for Optoelectronics, 409 Atomistilor St., 077125 Magurele (Romania); Zoita, N.C., E-mail: cnzoita@inoe.ro [National Institute for Optoelectronics, 409 Atomistilor St., 077125 Magurele (Romania); Danila, M. [National Institute for Research and Development in Microtechnology, 126A Erou Iancu Nicolae Blvd., 077190 Bucharest (Romania); Grigorescu, C.E.A. [National Institute for Optoelectronics, 409 Atomistilor St., 077125 Magurele (Romania); Logofatu, C. [National Institute of Materials Physics, 105 bis Atomistilor St., 077125 Magurele (Romania)

    2015-08-31

    Hetero-epitaxial TiC thin films were deposited at 100 °C on MgO(001) by DC reactive magnetron sputtering in a mixture of Ar and CH{sub 4}. The 62 nm thick films were analyzed for elemental composition and chemical bonding by Auger electron spectroscopy, X-ray photoelectron spectroscopy and micro-Raman spectroscopy. The crystallographic structure investigation by high resolution X-ray diffraction revealed that the films consist of two layers: an interface partially strained epilayer with high crystalline quality, and a relaxed layer, formed by columnar grains, maintaining the epitaxial relationship with the substrate. The films presented smooth surfaces (RMS roughness ~ 0.55 nm), with circular equi-sized grains/crystallites, as observed by atomic force microscopy. The Hall measurements in Van der Pauw geometry revealed relatively high resistivity value ~ 620 μΩ cm, ascribed to electron scattering on interfaces, on grain boundaries and on different defects/dislocations. - Highlights: • Hetero-epitaxial TiC{sub 0.84} thin films were grown on MgO(001) at 100 °C by magnetron sputtering. • 62 nm thick films were synthesized by magnetron sputtering, using Ti, Ar and CH{sub 4}. • The film comprises a partially strained interface epilayer and a relaxed top layer. • Both layers preserve the epitaxial relationship with the substrate. • Low RMS surface roughness ~ 0.55 nm and grains with mean lateral size of ~ 38.5 nm were observed.

  6. STRUCTURAL, PHOTO-FUNCTIONAL AND SEMICONDUCTOR PROPERTIES OF COPPER OXIDE THIN FILMS PREPARED BY DC REACTIVE METHOD UNDER VARIOUS THICKNESSES Anmar H. Shukur

    Directory of Open Access Journals (Sweden)

    Anmar H. Shukur

    2018-01-01

    Full Text Available Cuprous oxide (Cu2O has been formed on glass substrates by dc reactive magnetron sputtering method, whereas pure target of the solid copper was sputtered with a mixture of plasma for argon gas and oxygen gas was used to form these films. Under vacuum chamber pressure of 1.2×10-5 Pa, thin film thickness was changed from 100 nm to 300 nm while other deposition parameters were fixed. The influence of changing the thickness of thin films on the electrical and the optical properties was investigated in this study. X-ray photoelectron spectroscopy (XPS, X-ray Diffractions system XRD, Atomic Force Microscopy (AFM, hall effect measurement system, UV–VIS spectrophotometer were employed to determine the characteristic of the deposited thin films. Thin film of 200 nm has observed low resistivity of 60.63 Ω cm and direct band gap of 2.5eV. This study has demonstrated that the thickness has direct influence on electrical and optical properties.

  7. Reactive pulsed laser deposition of Cu2ZnSnS4 thin films in H2S

    International Nuclear Information System (INIS)

    Surgina, G.D.; Zenkevich, A.V.; Sipaylo, I.P.; Nevolin, V.N.; Drube, W.; Teterin, P.E.; Minnekaev, M.N.

    2013-01-01

    Cu 2 ZnSnS 4 (CZTS) thin films have been grown by reactive pulsed laser deposition in H 2 S atmosphere, combining the alternate ablation from the metallic (Cu) and alloyed (Zn x Sn) targets at room temperature. The morphological, structural and optical properties of as grown CZTS thin films with varying compositions as well as upon annealing in N 2 atmosphere are investigated by Rutherford backscattering spectrometry, X-ray diffraction, Raman spectroscopy and optical spectrophotometry. The chemical bonding in the “bulk” of the CZTS films is elucidated via hard X-ray photoemission spectroscopy measurements. The formation of the good quality stoichiometric polycrystalline CZTS films is demonstrated upon optimization of the growth parameters. - Highlights: ► The new method of Cu 2 ZnSnS 4 (CZTS) thin films growth in H 2 S was realized. ► CZTS films were grown by pulsed laser deposition from Cu and alloyed Zn–Sn targets. ► The effect of the processing parameters on the CZTS properties was investigated. ► The chemical bonding in the “bulk” of CZTS films was studied

  8. Gas-phase mechanisms in the growth of ZrCyN1-y thin films by pulsed reactive crossed-beam laser ablation

    International Nuclear Information System (INIS)

    Spillmann, H.; Clerc, C.; Doebeli, M.; Willmott, P.R.

    2002-01-01

    Superhard zirconium carbonitride films have been grown via pulsed reactive crossed-beam laser ablation (PRCLA) using zirconium metal and a nitrogen- and carbon-containing gas pulse mixture. The control of stoichiometry was much simplified by using the thermally stable gas-phase species N 2 and CH 4 . The gas-phase processes are investigated using quadrupole mass spectroscopy and optical emission spectroscopy. The excitation of the ablation plume depends intimately on the collision partner of the gas pulse, in particular on its density of states and the probability of energy transfer to internal degrees of freedom

  9. Growth and characterization of nitrogen-doped TiO2 thin films prepared by reactive pulsed laser deposition

    International Nuclear Information System (INIS)

    Sauthier, G.; Ferrer, F.J.; Figueras, A.; Gyoergy, E.

    2010-01-01

    Nitrogen-doped titanium dioxide (TiO 2 ) thin films were grown on (001) SiO 2 substrates by reactive pulsed laser deposition. A KrF* excimer laser source (λ = 248 nm, τ FWHM ≅ 10 ns, ν = 10 Hz) was used for the irradiations of pressed powder targets composed by both anatase and rutile phase TiO 2 . The experiments were performed in a controlled reactive atmosphere consisting of oxygen or mixtures of oxygen and nitrogen gases. The obtained thin film crystal structure was investigated by X-ray diffraction, while their chemical composition as well as chemical bonding states between the elements were studied by X-ray photoelectron spectroscopy. An interrelation was found between nitrogen concentration, crystalline structure, bonding states between the elements, and the formation of titanium oxinitride compounds. Moreover, as a result of the nitrogen incorporation in the films a continuous red-shift of the optical absorption edge accompanied by absorption in the visible spectral range between 400 and 500 nm wavelength was observed.

  10. Experimental subcritical reactivity determinations employing APSD measurements with pulse mode detectors in the IPEN/MB-01 reactor

    International Nuclear Information System (INIS)

    Santos, Adimir dos; Lee, Seung Min; Diniz, Ricardo; Jerez, Rogerio

    2011-01-01

    This work aims to determine experimentally the subcritical reactivity levels of several configurations of the IPEN/MB-01 reactor in an approach based on the subcritical kinetic model developed by Gandini and Salvatores. The procedure employs the measurements of the APSD (Auto Power Spectral Density) using pulse mode detectors. The proposed approach is based only on measured quantities such as counting rates and the parameters arising from the least square approach of the APSD. Other difficult quantity such as detector efficiencies is not needed in the method. Several measurements of APSD were performed in varying degrees of sub-criticality (up to around -7000 pcm). The APSD data were least-square fitted to get the prompt decay mode (α). Beside the startup source, an external neutron sources of Am-Be was installed near the core in order to improve neutron count statistics. The final experimental results are of very good quality. The experiment shows clearly that the classical one point kinetic theory cannot describe the measured reactivity. MCNP K eff results were compared to the corresponding experimental results. The agreement was fairly good. (author)

  11. Design of six pulse bridge multiplication converter model for current harmonic elimination of three phase ac-dc converter

    International Nuclear Information System (INIS)

    Soomro, M.A.; Helepoto, I.A.

    2014-01-01

    The recent development of semiconductor technology and wide spread use of power electronic devices in power system have open the era of the power system harmonics due to increasing penetration of non-linear loads. Harmonics are widely admitted as most important issues of power quality which must be eliminated to maintain power system reliability. The tolerable THD (Total Harmonic Distortion) values must be bounded in well-defined limits recognized by IEEE-519 standard. In this work, in order to eliminate the current harmonics produced by non-linear loads, six pulse multiplication converter technique in conjunction with STSSHPE (Single Tuned Shunt Harmonic Passive Filter) is proposed. The proposed model has the capacity of harmonic cancellation of the dominant 3rd order harmonics. Besides that, the 5th and 7th order harmonics are also reduced to a diminishing level. The hardware model has been experimentally tested by PQA (Power Quality Analyzer) and simulation model is designed using MATLAB software. The acquired results have been measured by considering THD values in terms of current and voltage. Furthermore, they have been compared against IEEE-519 performance standards. The prosed model, successfully bounds the total harmonic distortion under defined limits by IEEE-519 standard. (author)

  12. Control and enhancement of the oxygen storage capacity of ceria films by variation of the deposition gas atmosphere during pulsed DC magnetron sputtering

    Science.gov (United States)

    Eltayeb, Asmaa; Vijayaraghavan, Rajani K.; McCoy, Anthony; Venkatanarayanan, Anita; Yaremchenko, Aleksey A.; Surendran, Rajesh; McGlynn, Enda; Daniels, Stephen

    2015-04-01

    In this study, nanostructured ceria (CeO2) films are deposited on Si(100) and ITO coated glass substrates by pulsed DC magnetron sputtering using a CeO2 target. The influence on the films of using various gas ambients, such as a high purity Ar and a gas mixture of high purity Ar and O2, in the sputtering chamber during deposition are studied. The film compositions are studied using XPS and SIMS. These spectra show a phase transition from cubic CeO2 to hexagonal Ce2O3 due to the sputtering process. This is related to the transformation of Ce4+ to Ce3+ and indicates a chemically reduced state of CeO2 due to the formation of oxygen vacancies. TGA and electrochemical cyclic voltammetry (CV) studies show that films deposited in an Ar atmosphere have a higher oxygen storage capacity (OSC) compared to films deposited in the presence of O2. CV results specifically show a linear variation with scan rate of the anodic peak currents for both films and the double layer capacitance values for films deposited in Ar/O2 mixed and Ar atmosphere are (1.6 ± 0.2) × 10-4 F and (4.3 ± 0.5) × 10-4 F, respectively. Also, TGA data shows that Ar sputtered samples have a tendency to greater oxygen losses upon reduction compared to the films sputtered in an Ar/O2 mixed atmosphere.

  13. Plant regeneration from pulse-treated longitudinally sliced half cotyledon node explants of Turkish ochrus chickling [Lathyrus ochrus (L. D.C.

    Directory of Open Access Journals (Sweden)

    Saglam S.

    2012-01-01

    Full Text Available The forage legume ochrus chickling [Lathyrus ochrus (L. D.C.] which is distributed in the Mediterranean region, is gaining importance in terms of economy and agriculture in Turkey. However, the full potential of the legume has yet to be realized due to the presence of neurotoxin, β-N-oxalyl-L-a, β-diaminopropionic acid (ODAP causing lathyrism. This study aimed to develop an efficient micropropagation system using longitudinally sliced cotyledon node explants for use in Agrobacterium-mediated genetic transformation in the future. The results show that the maximum number of shoots per explant was achieved on MS medium solidified with 8 g/l isubgol gelled medium containing 0.30 mg/l BA-0.2 mg/l NAA. Well-developed shoots were rooted by pulse treatment with 50 mg/l IBA and culturing on an 8 g/l isubgol gel solidified MS medium. The results showed 60% rooting in the treated shoots. The rooted plantlets were transferred to pots containing sand and organic matter and acclimatized.

  14. Evaluation of the optoelectronic properties and corrosion behavior of Al2O3-doped ZnO films prepared by dc pulsed magnetron sputtering

    International Nuclear Information System (INIS)

    Zubizarreta, C; Berasategui, E G; Bayón, R; Barriga, J; Escobar Galindo, R; Barros, R; Gaspar, D; Nunes, D; Calmeiro, T; Martins, R; Fortunato, E

    2014-01-01

    The main requirements for transparent conducting oxide (TCO) films acting as electrodes are a high transmission rate in the visible spectral region and low resistivity. However, in many cases, tolerance to temperature and humidity exposure is also an important requirement to be fulfilled by the TCOs to assure proper operation and durability. Besides improving current encapsulation methods, the corrosion resistance of the developed TCOs must also be enhanced to warrant the performance of optoelectronic devices. In this paper the performance of aluminum-doped zinc oxide (AZO) films deposited by pulsed dc magnetron sputtering has been studied. Structure, optical transmittance/reflectance, electrical properties (resistivity, carrier concentration and mobility) and corrosion resistance of the developed coatings have been analyzed as a function of the doping of the target and the coating thickness. Films grown from a 2.0 wt% Al 2 O 3 target with a thickness of approximately 1 µm showed a very low resistivity of 6.54  ×  10 –4  Ωcm and a high optical transmittance in the visible range of 84%. Corrosion studies of the developed samples have shown very low corrosion currents (nanoamperes), very high corrosion resistances (in the order of 10 7  Ω) and very high electrochemical stability, indicating no tendency for electrochemical corrosion degradation. (paper)

  15. Evaluation of the optoelectronic properties and corrosion behavior of Al2O3-doped ZnO films prepared by dc pulsed magnetron sputtering

    Science.gov (United States)

    Zubizarreta, C.; Berasategui, E. G.; Bayón, R.; Escobar Galindo, R.; Barros, R.; Gaspar, D.; Nunes, D.; Calmeiro, T.; Martins, R.; Fortunato, E.; Barriga, J.

    2014-12-01

    The main requirements for transparent conducting oxide (TCO) films acting as electrodes are a high transmission rate in the visible spectral region and low resistivity. However, in many cases, tolerance to temperature and humidity exposure is also an important requirement to be fulfilled by the TCOs to assure proper operation and durability. Besides improving current encapsulation methods, the corrosion resistance of the developed TCOs must also be enhanced to warrant the performance of optoelectronic devices. In this paper the performance of aluminum-doped zinc oxide (AZO) films deposited by pulsed dc magnetron sputtering has been studied. Structure, optical transmittance/reflectance, electrical properties (resistivity, carrier concentration and mobility) and corrosion resistance of the developed coatings have been analyzed as a function of the doping of the target and the coating thickness. Films grown from a 2.0 wt% Al2O3 target with a thickness of approximately 1 µm showed a very low resistivity of 6.54  ×  10-4 Ωcm and a high optical transmittance in the visible range of 84%. Corrosion studies of the developed samples have shown very low corrosion currents (nanoamperes), very high corrosion resistances (in the order of 107 Ω) and very high electrochemical stability, indicating no tendency for electrochemical corrosion degradation.

  16. Phase transition and thermal expansion studies of alumina thin films prepared by reactive pulsed laser deposition.

    Science.gov (United States)

    Balakrishnan, G; Thirumurugesan, R; Mohandas, E; Sastikumar, D; Kuppusami, P; Songl, J I

    2014-10-01

    Aluminium oxide (Al2O3) thin films were deposited on Si (100) substrates at an optimized oxygen partial pressure of 3 x 10(-3) mbar at room temperature by pulsed laser deposition (PLD). The films were characterized by high temperature X-ray diffraction (HTXRD), field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). The HTXRD pattern showed the cubic y-Al2O3 phase in the temperature range 300-973 K. At temperatures ≥ 1073 K, the δ and θ-phases of Al2O3 were observed. The mean linear thermal expansion coefficient and volume thermal expansion coefficient of γ-Al2O3 was found to be 12.66 x 10(-6) K(-1) and 38.87 x 10(-6) K(-1) in the temperature range 300 K-1073 K. The field emission scanning electron microscopy revealed a smooth and structureless morphology of the films deposited on Si (100). The atomic force microscopy study indicated the increased crystallinity and surface roughness of the films after annealing at high temperature.

  17. TiCN thin films grown by reactive crossed beam pulsed laser deposition

    Science.gov (United States)

    Escobar-Alarcón, L.; Camps, E.; Romero, S.; Muhl, S.; Camps, I.; Haro-Poniatowski, E.

    2010-12-01

    In this work, we used a crossed plasma configuration where the ablation of two different targets in a reactive atmosphere was performed to prepare nanocrystalline thin films of ternary compounds. In order to assess this alternative deposition configuration, titanium carbonitride (TiCN) thin films were deposited. Two crossed plasmas were produced by simultaneously ablating titanium and graphite targets in an Ar/N2 atmosphere. Films were deposited at room temperature onto Si (100) and AISI 4140 steel substrates whilst keeping the ablation conditions of the Ti target constant. By varying the laser fluence on the carbon target it was possible to study the effect of the carbon plasma on the characteristics of the deposited TiCN films. The structure and composition of the films were analyzed by X-ray Diffraction, Raman Spectroscopy and non-Rutherford Backscattering Spectroscopy. The hardness and elastic modulus of the films was also measured by nanoindentation. In general, the experimental results showed that the TiCN thin films were highly oriented in the (111) crystallographic direction with crystallite sizes as small as 6.0 nm. It was found that the hardness increased as the laser fluence was increased, reaching a maximum value of about 33 GPa and an elastic modulus of 244 GPa. With the proposed configuration, the carbon content could be easily varied from 42 to 5 at.% by changing the laser fluence on the carbon target.

  18. Advanced DC/DC converters

    CERN Document Server

    Luo, Fang Lin

    2003-01-01

    DC/DC conversion techniques have undergone rapid development in recent decades. With the pioneering work of these authors, DC/DC converters have now moved into their sixth generation. This book offers a concise, practical presentation of DC/DC converters, summarizing the spectrum of conversion tecnologies and presentingmany new ideas and more than 100 new topologies. Nowhere else in the literature are DC/DC converters so logically sorted and systematically introduced, and nowhere else can readers find detailed information on prototype topologies that represent a major contribution to modern power engineering. More than 320 figures, 60 tables, and 500 formulae facilitate understand and provide precise data.

  19. A global plasma model for reactive deposition of compound films by modulated pulsed power magnetron sputtering discharges

    Science.gov (United States)

    Zheng, B. C.; Wu, Z. L.; Wu, B.; Li, Y. G.; Lei, M. K.

    2017-05-01

    A spatially averaged, time-dependent global plasma model has been developed to describe the reactive deposition of a TiAlSiN thin film by modulated pulsed power magnetron sputtering (MPPMS) discharges in Ar/N2 mixture gas, based on the particle balance and the energy balance in the ionization region, and considering the formation and erosion of the compound at the target surface. The modeling results show that, with increasing the N2 partial pressure from 0% to 40% at a constant working pressure of 0.3 Pa, the electron temperature during the strongly ionized period increases from 4 to 7 eV and the effective power transfer coefficient, which represents the power fraction that effectively heats the electrons and maintains the discharge, increases from about 4% to 7%; with increasing the working pressure from 0.1 to 0.7 Pa at a constant N2 partial pressure of 25%, the electron temperature decreases from 10 to 4 eV and the effective power transfer coefficient decreases from 8% to 5%. Using the modeled plasma parameters to evaluate the kinetic energy of arriving ions, the ion-to-neutral flux ratio of deposited species, and the substrate heating, the variations of process parameters that increase these values lead to an enhanced adatom mobility at the target surface and an increased input energy to the substrate, corresponding to the experimental observation of surface roughness reduction, the microstructure transition from the columnar structure to the dense featureless structure, and the enhancement of phase separation. At higher N2 partial pressure or lower working pressure, the modeling results demonstrate an increase in electron temperature, which shifts the discharge balance of Ti species from Ti+ to Ti2+ and results in a higher return fraction of Ti species, corresponding to the higher Al/Ti ratio of deposited films at these conditions. The modeling results are well correlated with the experimental observation of the composition variation and the microstructure

  20. Dc-To-Dc Converter Uses Reverse Conduction Of MOSFET's

    Science.gov (United States)

    Gruber, Robert P.; Gott, Robert W.

    1991-01-01

    In modified high-power, phase-controlled, full-bridge, pulse-width-modulated dc-to-dc converters, switching devices power metal oxide/semiconductor field-effect transistors (MOSFET's). Decreases dissipation of power during switching by eliminating approximately 0.7-V forward voltage drop in anti-parallel diodes. Energy-conversion efficiency increased.

  1. Effects of depletion sampling by standard three-pass pulsed DC electrofishing on blood chemistry parameters of fishes from Appalachian streams

    Science.gov (United States)

    Densmore, Christine L.; Panek, Frank M.

    2013-01-01

    Adverse effects on fishes captured by electrofishing techniques have long been recognized, although the extent of associated physical injury and behavioral alterations are highly variable and dependent on a number of factors. We examined the effects of three-pass pulsed DC (PDC) electrofishing on two salmonid species (Rainbow Trout Oncorhynchus mykiss and Brook Trout Salvelinus fontinalis) and five other genera (Green Sunfish Lepomis cyanellus, Potomac Sculpin Cottus girardi, Fathead Minnow Pimephales promelas, Largemouth Bass Micropterus salmoides, and Channel Catfish Ictalurus punctatus) common to Appalachian streams. We examined the corresponding effects of PDC electroshock on the following physiological indicators of stress and trauma: blood glucose and serum lactate, as well as on other blood chemistry, namely, enzymes, electrolytes, minerals, and proteins. All species demonstrated physiological responses to PDC electroshock, indicated by the biochemical differences in blood parameters in unshocked and shocked groups of fish with or without gross evidence of hemorrhagic trauma. Serum lactate was the most consistent indicator of these effects. Significant differences in whole blood glucose levels were also noted in treatment groups in all species except Green Sunfish, although the patterns observed were not as consistent as for serum lactate. Elevations in the serum enzymes, aspartate aminotransferase and creatine kinase, in the electroshocked fish occurred only in the two salmonid species. In many instances, although blood parameters were elevated in electroshocked fish compared with the unshocked controls for a given species, there were no differences in those levels in electroshocked fish based on the presence of gross hemorrhagic trauma to axial musculature. While some of the blood parameters examined correlated with both the occurrence of electroshock and the resultant tissue injury, there was no apparent link between the altered blood chemistry and

  2. Effect of deposition angle on the structure and properties of pulsed-DC magnetron sputtered TiAlN thin films

    International Nuclear Information System (INIS)

    Shetty, A.R.; Karimi, A.; Cantoni, M.

    2011-01-01

    This article reports the comparison of structure and properties of titanium aluminum nitride (TiAlN) films deposited onto Si(100) substrates under normal and oblique angle depositions using pulsed-DC magnetron sputtering. The substrate temperature was set at room temperature, 400 o C and 650 o C, and the bias was kept at 0, - 25, - 50, and - 80 V for both deposition angles. The surface and cross-section of the films were observed by scanning electron microscopy. It was found that as the deposition temperature increases, films deposited under normal incidence exhibit distinct faceted crystallites, whereas oblique angle deposited (OAD) films develop a kind of 'tiles of a roof' or 'stepwise structure', with no facetted crystallites. The OAD films showed an inclined columnar structure, with columns tilting in the direction of the incident flux. As the substrate temperature was increased, the tilting of columns nearly approached the substrate normal. Both hardness and Young's modulus decreases when the flux angle was changed from α = 0 o to 45 o as measured by nanoindentation. This was attributed to the voids formed due to the shadowing effect. The crystallographic properties of these coatings were studied by θ-2θ scan and pole figure X-ray diffraction. Films deposited at α = 0 o showed a mixed (111) and (200) out-of-plane orientation with random in-plane alignment. On the other hand, films deposited at α = 45 o revealed an inclined texture with (111) orientation moving towards the incident flux direction and the (200) orientation approaching the substrate normal, showing substantial in-plane alignment.

  3. Composition, structure and properties of SiN x films fabricated by pulsed reactive closed-field unbalanced magnetron sputtering

    International Nuclear Information System (INIS)

    Yao, Zh.Q.; Yang, P.; Huang, N.; Sun, H.; Wan, G.J.; Leng, Y.X.; Chen, J.Y.

    2005-01-01

    Silicon nitride (SiN x ) thin films are of special interest in both scientific research and industrial applications due to their remarkable properties such as high thermal stability, chemical inertness, high hardness and good dielectric properties. In this work, SiN x films were fabricated by pulsed reactive closed-field unbalanced magnetron sputtering of high purity single crystal silicon targets in an Ar-N 2 mixture. The effect of N 2 partial pressure on the film composition, chemical bonding configurations, surface morphology, surface free energy, optical and mechanical properties were investigated. We showed that with increased N 2 partial pressure, the N to Si ratio (N/Si) in the film increased and N atoms are preferentially incorporated in the NSi 3 stoichiometric configuration. It leads the Si-N network a tendency to chemical order. Films deposited at a high N 2 fraction were consistently N-rich. The film surface transformed from a loose granular structure with microporosity to a homogeneous, continuous, smooth and dense structure. A progressive densification of the film microstructure occurs as the N 2 fraction is increased. The reduced surface roughness and the increased N incorporation in the film give rise to the increased contact angle with double-distilled water from 24 o to 49.6 o . To some extent, the SiN x films deposited by pulsed magnetron sputtering are hydrophilic in nature. The as-deposited SiN x films exhibit good optical transparency in the visible region and the optical band gap E opt can be varied from 1.68 eV for a-Si to 3.62 eV for SiN x films, depending on the synthesis parameters. With the increase of the N/Si atomic ratio, wear resistance of the SiN x films was improved, a consequence of increased hardness and elastic modulus. The SiN x films have lower friction coefficient and better wear resistance than 316L stainless steel under dry sliding friction, where the SiN x films experienced only fatigue wear

  4. Determination of reactivity of multiplying systems filled with spherical HTGR-fuel elements using kinetic methods with regard to the pulsed-neutron method

    International Nuclear Information System (INIS)

    Drueke, V.

    1978-06-01

    At three critical or subcritical facilities - two of them filled with spherical HTGR-fuel elements - the reactivity is determined using kinetic methods. Besides the inverskinetic method the applicability of the pulsed-neutron method is investigated. The experimental results using the pulsed-neutron method are compared partly with the inverskinetic method and partly with diffusion-calculations. It is shown, that in the HTGR the space dependence of the reactivity in radial direction is not remarkable in spite of the 'kinetic distortion'; on the contrary in axial direction - the direction of the external neutron source - space dependent reactivity worths are measured. The results of the pulsed-neutron methods of Sjoestrand and Simmons-King are rather good applicable in all configurations. For the method of Sjoestrand it is necessary to select the detector positions, whereas for Simmons-King the calculated life-time determines the results. Therefore it is proposed to compare calculated and measured decay constants of the prompt neutron field in future. (orig.) [de

  5. Nanoscale multilayered and porous carbide interphases prepared by pressure-pulsed reactive chemical vapor deposition for ceramic matrix composites

    International Nuclear Information System (INIS)

    Jacques, S.; Jouanny, I.; Ledain, O.; Maillé, L.; Weisbecker, P.

    2013-01-01

    In Ceramic Matrix Composites (CMCs) reinforced by continuous fibers, a good toughness is achieved by adding a thin film called “interphase” between the fiber and the brittle matrix, which acts as a mechanical fuse by deflecting the matrix cracks. Pyrocarbon (PyC), with or without carbide sub-layers, is typically the material of choice to fulfill this role. The aim of this work was to study PyC-free nanoscale multilayered carbide coatings as interphases for CMCs. Nanoscale multilayered (SiC–TiC) n interphases were deposited by pressure-Pulsed Chemical Vapor Deposition (P-CVD) on single filament Hi-Nicalon fibers and embedded in a SiC matrix sheath. The thicknesses of the carbide interphase sub-layers could be made as low as a few nanometers as evidenced by scanning and transmission electron microscopy. By using the P-ReactiveCVD method (P-RCVD), in which the TiC growth involves consumption of SiC, it was not only possible to obtain multilayered (SiC–TiC) n films but also TiC films with a porous multilayered microstructure as a result of the Kirkendall effect. The porosity in the TiC sequences was found to be enhanced when some PyC was added to SiC prior to total RCVD consumption. Because the porosity volume fraction was still not high enough, the role of mechanical fuse of the interphases could not be evidenced from the tensile curves, which remained fully linear even when chemical attack of the fiber surface was avoided.

  6. Nanoscale multilayered and porous carbide interphases prepared by pressure-pulsed reactive chemical vapor deposition for ceramic matrix composites

    Science.gov (United States)

    Jacques, S.; Jouanny, I.; Ledain, O.; Maillé, L.; Weisbecker, P.

    2013-06-01

    In Ceramic Matrix Composites (CMCs) reinforced by continuous fibers, a good toughness is achieved by adding a thin film called "interphase" between the fiber and the brittle matrix, which acts as a mechanical fuse by deflecting the matrix cracks. Pyrocarbon (PyC), with or without carbide sub-layers, is typically the material of choice to fulfill this role. The aim of this work was to study PyC-free nanoscale multilayered carbide coatings as interphases for CMCs. Nanoscale multilayered (SiC-TiC)n interphases were deposited by pressure-Pulsed Chemical Vapor Deposition (P-CVD) on single filament Hi-Nicalon fibers and embedded in a SiC matrix sheath. The thicknesses of the carbide interphase sub-layers could be made as low as a few nanometers as evidenced by scanning and transmission electron microscopy. By using the P-ReactiveCVD method (P-RCVD), in which the TiC growth involves consumption of SiC, it was not only possible to obtain multilayered (SiC-TiC)n films but also TiC films with a porous multilayered microstructure as a result of the Kirkendall effect. The porosity in the TiC sequences was found to be enhanced when some PyC was added to SiC prior to total RCVD consumption. Because the porosity volume fraction was still not high enough, the role of mechanical fuse of the interphases could not be evidenced from the tensile curves, which remained fully linear even when chemical attack of the fiber surface was avoided.

  7. High C reactive protein associated with increased pulse wave velocity among urban men with metabolic syndrome in Malaysia.

    Science.gov (United States)

    Aminuddin, Amilia; Zakaria, Zaiton; Fuad, Ahmad F; Kamsiah, Jaarin; Othman, Faizah; Das, Srijit; Kamisah, Yusof; Qodriyah, Haji S; Jubri, Zakiah; Nordin, Nor Anita M; Ngah, Wan Z

    2013-03-01

    To determine the association between carotid femoral pulse wave velocity (PWVCF); augmentation index (AI); and high-sensitivity C reactive protein (hs-CRP) with metabolic syndrome (MetS), and to determine the influence of ethnicity on PWVCF and AI, and the association between high hs-CRP and increased PWV, and AI in MetS. A cross-sectional study was conducted at Universiti Kebangsaan Malaysia Medical Center, Kuala Lumpur, Malaysia from September 2009 to September 2011. Three hundred and eighty men (Chinese and Malays) were recruited from the study. The PWVCF and AI were measured by Vicorder (SMT Medical, Wuerzburg, Germany). The hs-CRP level was also determined. We defined MetS using the International Diabetes Federation (IDF) and harmonized criteria. Malays had higher AI compared to the Malaysian Chinese. Patients with MetS had higher PWVCF (IDF criteria: 8.5 [8.3-8.7] versus 8.2 [8.0-8.4] m/s, p=0.03; harmonized criteria: 8.5 [8.4-8.7] versus 8.2 [8.0-8.4] m/s, p=0.007) and hs-CRP (IDF criteria: 0.9+/-2.0 versus 0.4+/-1.1 mg/L, p=0.0007; harmonized criteria: 0.8+/-1.9 versus 0.4+/-1.1 mg/L, p=0.002) compared to non-MetS. In subjects with MetS, those with high hs-CRP (>3 mg/L) had higher PWVCF. Augmentation index values were significantly higher in Malays compared with Malaysian Chinese. Metabolic syndrome was associated with increased PWVCF and hs-CRP. Patients with MetS and high hs-CRP were associated with higher PWVCF. The measurement of hs-CRP reflects the degree of subclinical vascular damage in MetS.

  8. dc Arc Fault Effect on Hybrid ac/dc Microgrid

    Science.gov (United States)

    Fatima, Zahra

    The advent of distributed energy resources (DER) and reliability and stability problems of the conventional grid system has given rise to the wide spread deployment of microgrids. Microgrids provide many advantages by incorporating renewable energy sources and increasing the reliability of the grid by isolating from the main grid in case of an outage. AC microgrids have been installed all over the world, but dc microgrids have been gaining interest due to the advantages they provide over ac microgrids. However the entire power network backbone is still ac and dc microgrids require expensive converters to connect to the ac power network. As a result hybrid ac/dc microgrids are gaining more attention as it combines the advantages of both ac and dc microgrids such as direct integration of ac and dc systems with minimum number of conversions which increases the efficiency by reducing energy losses. Although dc electric systems offer many advantages such as no synchronization and no reactive power, successful implementation of dc systems requires appropriate protection strategies. One unique protection challenge brought by the dc systems is dc arc faults. A dc arc fault is generated when there is a gap in the conductor due to insulation degradation and current is used to bridge the gap, resulting in an arc with very high temperature. Such a fault if it goes undetected and is not extinguished can cause damage to the entire system and cause fires. The purpose of the research is to study the effect of the dc arc fault at different locations in the hybrid ac/dc microgrid and provide insight on the reliability of the grid components when it is impacted by arc faults at various locations in the grid. The impact of dc arc fault at different locations on the performance of the PV array, wind generation, and constant power loads (CPL) interfaced with dc/dc converters is studied. MATLAB/Simulink is used to model the hybrid ac/dc microgrid and arc fault.

  9. Peripheral Blood CD4 T-Cell and Plasmacytoid Dendritic Cell (pDC) Reactivity to Herpes Simplex Virus 2 and pDC Number Do Not Correlate with the Clinical or Virologic Severity of Recurrent Genital Herpes

    Science.gov (United States)

    Moss, Nicholas J.; Magaret, Amalia; Laing, Kerry J.; Kask, Angela Shaulov; Wang, Minna; Mark, Karen E.; Schiffer, Joshua T.; Wald, Anna

    2012-01-01

    Leukocytes participate in the immune control of herpes simplex virus (HSV). Data from HIV coinfections, germ line mutations, and case reports suggest involvement of CD4 T cells and plasmacytoid dendritic cells (pDC). We investigated the relationships between these cells and recurrent genital herpes disease severity in the general population. Circulating CD4 T-cell responses to HSV-2 were measured in specimens from 67 immunocompetent individuals with measured genital lesion and HSV shedding rates. Similarly, pDC number and functional responses to HSV-2 were analyzed in 40 persons. CD4 responses and pDC concentrations and responses ranged as much as 100-fold between persons while displaying moderate within-person consistency over time. No correlations were observed between these immune response parameters and genital HSV-2 severity. Cytomegalovirus (CMV) coinfection was not correlated with differences in HSV-2-specific CD4 T-cell responses. The CD4 T-cell response to HSV-2 was much more polyfunctional than was the response to CMV. These data suggest that other immune cell subsets with alternate phenotypes or anatomical locations may be responsible for genital herpes control in chronically infected individuals. PMID:22761381

  10. Preparation of hydrogenated amorphous carbon films using a microsecond-pulsed DC capacitive-coupled plasma chemical vapor deposition system operated at high frequency up to 400 kHz

    Science.gov (United States)

    Mamun, Md Abdullah Al; Furuta, Hiroshi; Hatta, Akimitsu

    2018-06-01

    Hydrogenated amorphous carbon (a-C:H) films are deposited on silicon (Si) substrates using a high-repetition microsecond-pulsed DC plasma chemical vapor deposition (CVD) system from acetylene (C2H2) at a gas pressure of 15 Pa inside a custom-made vacuum chamber. The plasma discharge characteristics, hydrocarbon species, and the microstructure of the resulting films are examined at various pulse repetition rates from 50 to 400 kHz and a fixed duty cycle of 50%. The optical emission spectra confirmed the increase in electron excitation energy from 1.09 to 1.82 eV and the decrease in the intensity ratio of CH/C2 from 1.04 to 0.75 with increasing pulse frequency, indicating the enhanced electron impact dissociation of C2H2 gas. With increasing pulse frequency, the deposition rate gradually increased, reaching a maximum rate of 60 nm/min at 200 kHz, after which a progressive decrease was noted, whereas the deposition area was almost uniform for all the prepared films. Clear trends of increasing sp3 content (amorphization) and decreasing hydrogen (H) content in the films were observed as the pulse repetition rate increased, while most of the hydrogen atoms bonded to carbon atoms by sp3 hybridization rather than by sp2 hybridization.

  11. The performance of the DC motor by the PID controlling PWM DC-DC boost converter

    OpenAIRE

    Can, Erol; Sayan, Hasan Hüseyin

    2017-01-01

    This paper presents the PID controlling direct current (DC) to the direct current boost converter feds DC motor which has a 3.68 kW and 240 V of DC voltage input on its characteristics. What is first formed is the boost converter mathematical model at the design stage. Secondly, a mathematical model of the DC motor is created so that the boost converter with the machine can be established and modeled at the Matlab Simulink. The PID controller is considered for arranging a pulse width modulati...

  12. Milliwatt dc/dc Inverter

    Science.gov (United States)

    Mclyman, C. W.

    1983-01-01

    Compact dc/dc inverter uses single integrated-circuit package containing six inverter gates that generate and amplify 100-kHz square-wave switching signal. Square-wave switching inverts 10-volt local power to isolated voltage at another desired level. Relatively high operating frequency reduces size of filter capacitors required, resulting in small package unit.

  13. Production and correlation of reactive oxygen and nitrogen species in gas- and liquid-phase generated by helium plasma jets under different pulse widths

    Science.gov (United States)

    Liu, Zhijie; Zhou, Chunxi; Liu, Dingxin; Xu, Dehui; Xia, Wenjie; Cui, Qingjie; Wang, Bingchuan; Kong, Michael G.

    2018-01-01

    In this paper, we present the effects of the pulse width (PW) on the plasma jet's discharge characteristics, particularly focusing on the production and correlation of the reactive oxygen and nitrogen species (RONS) in gas- and liquid-phase. It is found that the length of plasma jet plume first increases before the PW of 10 μs, then gradually decreases and finally almost remains unchanged beyond 150 μs. The plasma bullet disappears after the falling edge of the voltage pulse at low PW, while it terminates far ahead of the falling edge of voltage pulse at high PW. This is mainly attributed to accumulation of space charges that lead to weakening of the reduced electric field with an increase of PW from low to high. More important, it is found that the excited reactive species, the positive and negative ions from plasma jet, and the concentrations of NO2- and NO3- in deionized water exposed to plasma jet also display the first increasing and then decreasing change trend with increase of PW, while the concentration of H2O2 in water almost displays the linearly increasing trend. This mainly results from the formation of the H3O+ and HO2-, as well as their ion water clusters that can produce more OH radicals to be converted into H2O2, while the NO2- and NO3- in gas phase can transport into water and exist most stably in water. The water cluster formation at gas-liquid interface is an important key process that can affect the chemical nature and dose of aqueous RONS in water; this is beneficial for understanding how the RONS are formed in liquid-phase.

  14. Multibloc system electronic equipment: D.C. linear - logarithmic amplifier and periodmeter and wide range (pulses, fluctuations and direct current) measuring set

    International Nuclear Information System (INIS)

    Guerre, J.; Plaige, Y.; Vaux, C.

    1974-01-01

    The requirements which have led to the design of a specific equipment for reactor neutron control (Multibloc system) are briefly recalled. It is shown how, for reasons of saving the cost of installation, the development tended towards a multifunction performance from signals delivered by one detector. Two major achievments in accordance with the above trend are described: the D.C. linear - logarithmic amplifier and periodmeter, and the wide dynamics range measuring set [fr

  15. Simulating and Testing a DC-DC Half-Bridge SLR Converter

    Science.gov (United States)

    2013-06-01

    future pulse power demands with ship power, a large bank of capacitors or similar rapid discharge source is required. If capacitors are charged...Single Pulsed Avalanche Energy (j) I" Avalanche Current (i) E,, Repetilive Avalanche Energy (i) dv/dt Peak Diode Recovery dv/dt ® Po Total Power...SLR), battery charging, DC-DC, pulse power, power electronics, SLR converter 15. NUMBER OF PAGES 119 16. PRICE CODE 17. SECURITY CLASSIFICATION

  16. Virtual-vector-based space vector pulse width modulation of the DC-AC multilevel-clamped multilevel converter (MLC2)

    DEFF Research Database (Denmark)

    Rodriguez, Pedro; Busquets-Monge, Sergio; Blaabjerg, Frede

    2011-01-01

    This work presents the development of the space vector pulse width modulation (SVPWM) of a new multi-level converter topology. First, the proposed converter and its natural space vector diagram are presented. Secondly, a modified space vector diagram based on the virtual-vectors technique is show...

  17. Chemical analysis of reactive species and antimicrobial activity of/nwater treated by nanosecond pulsed DBD air plasma

    Czech Academy of Sciences Publication Activity Database

    Laurita, R.; Barbieri, D.; Gherardi, M.; Colombo, V.; Lukeš, Petr

    2015-01-01

    Roč. 3, č. 2 (2015), s. 53-61 ISSN 2212-8166 R&D Projects: GA MŠk(CZ) LD14080 Grant - others:European Cooperation in Science and Technology(XE) COST TD1208 Institutional support: RVO:61389021 Keywords : Dielectric barrier discharge * Plasma activated water * Reactive species * Peroxynitrite * Phenol degradation * Candida albicans * Staphylococcus aureus * Antimicrobial activity * Nosocomial infections Subject RIV: BL - Plasma and Gas Discharge Physics http://www.sciencedirect.com/science/article/pii/S2212816615300081

  18. Investigation of reactivity of inorganic free radicals relative to ferrocyanide- and octacyanomolybdate-ions in aqueous solutions by the method of pulse radiolysis

    International Nuclear Information System (INIS)

    Gogolev, A.V.; Fedoseev, A.M.; Makarov, I.F.; Pikaev, A.K.

    1989-01-01

    In aqueous solutions by the method of pulse radiolysis (dose per impulse-7.96-47.8 Gy, electron energy-5 MeV) the reactivity of Cl 2 - , Br 2 - , I 2 - , (SCN) 2 - , CO 3 - , SeO 3 - , SO 4 - radicals towards ferrocyanide ions and of Br 2 - , CO 3 - , SO 4 - radicals tawards octacyanomolybdate ions is studied. Linear dependence of rate constant logarithm of Cl 2 - , Br 2 - , I 2 - reactions with cyanide complexes on the difference of redox potentials of reacting particles ΔE 0 is obtained. Radicals containing oxygen react with cyanide complexes more rapidly than can be expected on the basis of ΔE 0 values. The effect of solution ionic strength, charge of reacting particles and radical nature on the reaction rate is discussed

  19. Studies of the composition, tribology and wetting behavior of silicon nitride films formed by pulsed reactive closed-field unbalanced magnetron sputtering

    International Nuclear Information System (INIS)

    Yao, Zh.Q.; Yang, P.; Huang, N.; Wang, J.; Wen, F.; Leng, Y.X.

    2006-01-01

    Silicon nitride films were formed by pulsed reactive closed-field unbalanced magnetron sputtering of high purity Si targets in an Ar-N 2 mixture. The effects of N 2 fraction on the chemical composition, and tribological and wetting behaviors were investigated. The films deposited at a high N 2 fraction were consistently N-rich. The surface microstructure changed from continuous granular surrounded by tiny void regions to a homogeneous and dense microstructure, and densitied as the N 2 fraction is increased. The as-deposited films have a relatively low friction coefficient and better wear resistance than 316L stainless steel under dry sliding friction and experienced only abrasive wear. The decreased surface roughness and increased nitrogen incorporation in the film give rise to increased contact angle with double-stilled water from 24 deg. to 49.6 deg. To some extent, the silicon nitride films deposited are hydrophilic in nature

  20. Oxygen diffusion kinetics and reactive lifetimes in bacterial and mammalian cells irradiated with nanosecond pulses of high intensity electrons

    International Nuclear Information System (INIS)

    Epp, E.R.; Weiss, H.; Ling, C.C.; Djordjevic, B.; Kessaris, N.D.

    1975-01-01

    Experiaments have been designed to gain information on the lifetime of oxygen-sensitive species suspected to be produced in critical molecules in irradiated cells and on the time-diffusion of oxygen in cells. An approach developed in this laboratory involves the delivery of two high intensity electron pulses each of 3 ns duration to a thin layer of cells equilibrated with a known concentration of oxygen. The first pulse serves to render the cells totally anoxic by the radiochemical depletion of oxygen; the second is delivered at a time electronically delayed after the first allowing for diffusion of oxygen during this time. Under these conditions the radiosensitivity of E coli B/r has been measured over six decades of interpulse time. Cellular time-diffusion curves constructed from the measurements show that oxygen establishes its sensitizing effect within 10 -4 s after the creation of intracellular anoxia establishing this time as an upper limit to the lifetime of the species. Unusual behaviour of the diffusion curve observed for longer delay times can be explained by a model wherein it is postulated that a radiation-induced inhibiting agent slows down diffusion. Application of this model to the experimental data yields a value of 0.4x10 -5 cm 2 s -1 for the cellular oxygen diffusion coefficient. Similar experiments recently carried out for Serratia marcescens will also be described. The oxygen effect in cultured HeLa cells exposed to single short electron pulses has been examined over a range of oxygen concentrations. A family of breaking survival curves was obtained similar to those previously measured for E coli B/r by this laboratory. The data appear to be reasonably consistent with a physicochemical mechanism involving the radiochemical depletion of oxygen previously invoked for bacteria. (author)

  1. Reactivity of OH radicals with chlorobenzoic acids-A pulse radiolysis and steady-state radiolysis study

    DEFF Research Database (Denmark)

    Zona, Robert; Solar, Sonja; Getoff, Nikola

    2010-01-01

    The reactions of OH radicals with 2-, 3-, 4-chlorobenzoic acids (ClBzA) and chlorobenzene (ClBz), k(OH+substrates)=(4.5−6.2)×109 dm3 mol−1 s−1, have been studied by pulse radiolysis in N2O saturated solutions. The absorption maxima of the OH-adducts were in the range of 320−340 nm. Their decay wa...... to degradation. The order for the efficiency of dehalogenation was 4->2->3-ClBzA. Several primary radiolytic products could be detected by HPLC. To evaluate the toxicity of final products a bacterial bioluminescence test was carried out....

  2. Decentralized Interleaving of Paralleled Dc-Dc Buck Converters: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Brian B [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Rodriguez, Miguel [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Sinha, Mohit [University of Minnesota; Dhople, Sairaj [University of Minnesota; Poon, Jason [University of California at Berkeley

    2017-09-01

    We present a decentralized control strategy that yields switch interleaving among parallel connected dc-dc buck converters without communication. The proposed method is based on the digital implementation of the dynamics of a nonlinear oscillator circuit as the controller. Each controller is fully decentralized, i.e., it only requires the locally measured output current to synthesize the pulse width modulation (PWM) carrier waveform. By virtue of the intrinsic electrical coupling between converters, the nonlinear oscillator-based controllers converge to an interleaved state with uniform phase-spacing across PWM carriers. To the knowledge of the authors, this work represents the first fully decentralized strategy for switch interleaving of paralleled dc-dc buck converters.

  3. Analysis of a high power, resonant DC-DC converter for DC wind turbines

    DEFF Research Database (Denmark)

    Dincan, Catalin Gabriel; Kjær, Philip Carne; Chen, Yu-Hsing

    2018-01-01

    This paper is introducing a new method of operation for a series resonant converter, with intended application in megawatt high-voltage DC wind turbines. Compared to a frequency controlled series resonant converter operated in sub resonant mode, the method (entitled pulse removal technique) allows...

  4. Comparative study of total power density at a substrate in pulsed DC magnetron and hollow-cathode plasma jet sputtering systems

    Czech Academy of Sciences Publication Activity Database

    Čada, Martin; Virostko, Petr; Kment, Štěpán; Hubička, Zdeněk

    2009-01-01

    Roč. 6, S1 (2009), S247-S252 ISSN 1612-8850. [International Conference on Plasma Surface Engineering /11./. Garmisch Partenkirchen, 15.09.2008-19.09.2008] R&D Projects: GA AV ČR KAN301370701; GA AV ČR KJB100100707; GA AV ČR KJB100100805; GA MŠk(CZ) 1M06002 Institutional research plan: CEZ:AV0Z10100522 Keywords : calorimeter probe * floating substrate * magnetron * plasma jet * pulsed discharge Subject RIV: BH - Optics, Masers, Lasers Impact factor: 4.037, year: 2009

  5. Final design of the Korean AC/DC converters for the ITER coil power supply system

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Jong-Seok, E-mail: jsoh@nfri.re.kr [ITER Korea, National Fusion Research Institute, Daejeon 305-806 (Korea, Republic of); Choi, Jungwan; Suh, Jae-Hak; Choi, Jihyun [ITER Korea, National Fusion Research Institute, Daejeon 305-806 (Korea, Republic of); Lee, Lacksang; Kim, Changwoo; Park, Hyungjin; Jo, Seongman; Lee, Seungyun; Hwang, Kwangcheol; Liu, Hyoyol [Dawonsys Corp., Siheung 429-450 (Korea, Republic of); Hong, Ki-Don; Sim, Dong-Joon; Lee, Jang-Soo [Hyosung Corp., Gongdeok-Dong, Seoul 121-720 (Korea, Republic of); Lee, Eui-Jae; Kwon, Yang-Hae; Lee, Dae-Yeol; Ko, Ki-Won; Kim, Jong-Min [Mobiis Corp., Yangjae-dong, Seoul 137-888 (Korea, Republic of); Song, Inho [ITER Organization, Route de Vinon sur Verdon, CS 90 046, 13067 St. Paul Lez Durance Cedex (France); and others

    2015-10-15

    The final design of the ITER TF, CS, CC and VS AC/DC converters has been completed to implement ITER requirements following the detailed design and refinements of the preliminary design. The number of parallel thyristors and the rating of fuses are coordinated to keep those devices within the explosion limit even under most severe fault conditions. The impedance of the converter transformer has been optimized taking into account the energization inrush current, short circuit current, reactive power consumption and the available DC voltage. To ensure system integrity, AC/DC converters are mechanically divided into transformers, AC busbars, 6-pulse bridges, DC interconnecting busbars and DC reactors, and then all subsystems are decoupled by flexible links. To provide stable real time network communication down to the converters, a one GbE link is deployed between master controllers and local controllers. IEEE 1588 is implemented to the embedded controllers for precision time synchronization. This paper describes the detailed solutions implemented in the final design for the ITER AC/DC converters with R&D results of converter prototypes.

  6. A Unidirectional DC-DC Autotransformer for DC Grid Application

    Directory of Open Access Journals (Sweden)

    Meng Zhou

    2018-03-01

    Full Text Available Conventional unidirectional DC-DC converters for DC grid application employ DC-AC-DC two-stage conversion technology and suffer from high converter cost and power loss. To solve these issues, a unidirectional step-up DC-DC autotransformer (UUDAT and a unidirectional step-down DC-DC autotransformer (DUDAT are studied. The UUDAT and DUDAT are composed of a series connection of diode bridges and voltage source converters. Topologies of UUDAT and DUDAT are detailed. The harmonic and un-controllability issues are discussed. Control and possible application scenarios for UUDAT and DUDAT are depicted. DC fault isolation mechanism and the methods of dimensioning the voltage and power ratings of the components in UUDAT and DUDAT are studied. Extensive simulations on power system level and experiments on a UUDAT and DUDAT prototype verified their technical feasibility.

  7. Tube Inner Coating of Non-Conductive Films by Pulsed Reactive Coaxial Magnetron Plasma with Outer Anode

    Directory of Open Access Journals (Sweden)

    Musab Timan Idriss Gasab

    2018-03-01

    Full Text Available The double-ended coaxial magnetron pulsed plasma (DCMPP method with auxiliary outer anode was introduced in order to achieve the uniform coating of non-conductive thin films on the inner walls of insulator tubes. In this study, titanium (Ti was employed as a cathode (sputtering target, and a glass tube was used as a substrate. In an argon (Ar and oxygen (O2 gas mixture, magnetron plasma was generated. Oxygen gas was introduced to deposit a titanium oxide (TiO2 film. A comparison between films coated with and without an auxiliary outer anode was made. As a result, it was clearly shown that the DCMPP method using an auxiliary outer anode enhanced the uniformity of the deposited non-conductive film compared to the conventional DCMPP method. Moreover, the optimum conditions under which the thin TiO2 film was deposited on the inner wall of the glass tube were revealed. From the results, it was supposed that the auxiliary outer anode contributed to the uniformity of the distributions of deposited negative charge on the non-conductive film and consequently the electric field and the plasma density uniform.

  8. Study by γ radiolysis and pulsed radiolysis of the reactivity of the superoxide ion in the oxyhemoglobin-methemoglobin system

    International Nuclear Information System (INIS)

    Haristoy, Didier.

    1976-01-01

    γ radiolysis of aqueous solutions of methemoglobin (MetHb) in the presence of formate ions, shows that only 25% of the total protein is reduced in oxyhemoglobin (HbO 2 ) by superoxide ions O 2 - according to the reaction MetHb+O 2 - →HbO 2 . The result can be attributed neither to the reactions of O 2 - with HbO 2 , nor the oxidation of HbO 2 by H 2 O 2 produced in the radiolysis of water and by dismutation of O 2 - . Pulse radiolysis studies of this reaction strongly suggest the formation of a transient complex 'MetHbO 2 - ' during the reaction. In addition to the well known self-oxidation of HbO 2 , these results show the existence of an equilibrium between HbO 2 and MetHb+O 2 - . Such an equilibrium could give rise, 'in vivo' to a nearly steady concentration of superoxide ions which could initiate a reaction favoring oxidation by oxygen [fr

  9. Reactivity of OH radicals with chlorobenzoic acids-A pulse radiolysis and steady-state radiolysis study

    Energy Technology Data Exchange (ETDEWEB)

    Zona, Robert [University of Vienna, Department of Nutritional Sciences, Section Radiation Biology, UZAII, Althanstrasse 14, A-1090 Vienna (Austria); Solar, Sonja, E-mail: sonja.solar@univie.ac.a [University of Vienna, Department of Nutritional Sciences, Section Radiation Biology, UZAII, Althanstrasse 14, A-1090 Vienna (Austria); Getoff, Nikola [University of Vienna, Department of Nutritional Sciences, Section Radiation Biology, UZAII, Althanstrasse 14, A-1090 Vienna (Austria); Sehested, Knud; Holcman, Jerzy [RISO National Laboratory Environmental Science and Technology Department, DK-4000, Roskilde (Denmark)

    2010-05-15

    The reactions of OH radicals with 2-, 3-, 4-chlorobenzoic acids (ClBzA) and chlorobenzene (ClBz), k({sup c}entre dotOH+substrates)=(4.5-6.2)x10{sup 9} dm{sup 3} mol{sup -1} s{sup -1}, have been studied by pulse radiolysis in N{sub 2}O saturated solutions. The absorption maxima of the OH-adducts were in the range of 320-340 nm. Their decay was according to a second-order reaction, 2k=(1-9)x10{sup 8} dm{sup 3} mol{sup -1} s{sup -1}. In the presence of N{sub 2}O/O{sub 2} the formation of peroxyl radicals was detectable for 2-, 4-ClBzA and ClBz, k(OH-adduct+O{sub 2})=(2-4)x10{sup 7} dm{sup 3} mol{sup -1} s{sup -1}, while this reaction for 3-ClBzA was too slow to be registered. In the presence of N{sub 2}O the degradation rates induced by gamma radiation were very similar for all chlorobenzoic acids, yet the chloride formation was distinctly higher for 3-ClBzA. In the presence of oxygen the initial degradation of 2-and 4-ClBzA equaled the OH-radical concentration, whereas in case of 3-ClBzA only approx60% of {sup c}entre dotOH led to degradation. The order for the efficiency of dehalogenation was 4->2->3-ClBzA. Several primary radiolytic products could be detected by HPLC. To evaluate the toxicity of final products a bacterial bioluminescence test was carried out.

  10. Design and preliminary characterization of a miniature pulsed RF APGD torch with downstream injection of the source of reactive species

    International Nuclear Information System (INIS)

    Leveille, V; Coulombe, S

    2005-01-01

    The design of a miniature low-power atmospheric pressure glow discharge torch (APGD-t) and the results of its preliminary electrical and spectroscopic characterization are presented. A capacitively-coupled pulsed RF (13.56 MHz) helium plasma jet is formed in a converging confinement tube and O 2 is injected downstream in the plasma afterglow region through a capillary electrode. With 1 SLM He, the APGD-t produced a non-thermal plasma jet of 500 μm-diameter and ∼2.5 mm-long at power levels ranging from 1 to 5 W. At ∼1 W, the gas temperature and He excitation temperature near the nozzle exit were ∼50 0 C and slightly below 2000 K, respectively. The breakdown voltage in 1 SLM He is approximately 220 V pk-to-0 . Careful electric probe measurements and circuit analysis revealed the strong effect of the voltage probe on the total load impedance. The injection of 10 SCCM O 2 through the capillary electrode led to the transport of atomic O further downstream in the plasma jet and to a slight increase of the He excitation temperature without significant effects on the electrical properties and jet length. Alternatively, the addition of an equivalent amount of O 2 (1 v/v%) to the plasma-forming gas affected the electrical properties slightly, but led to a drastic contraction of the plasma jet. The atomic oxygen production and transport conditions provided by the APGD-t are promising for precise bio-applications such as the treatment of skin tissues and cells

  11. Step-Up DC-DC converters

    DEFF Research Database (Denmark)

    Forouzesh, Mojtaba; Siwakoti, Yam P.; Gorji, Saman A.

    2017-01-01

    on the general law and framework of the development of next-generation step-up dc-dc converters, this paper aims to comprehensively review and classify various step-up dc-dc converters based on their characteristics and voltage-boosting techniques. In addition, the advantages and disadvantages of these voltage...

  12. Preparation and comparison of a-C:H coatings using reactive sputter techniques

    Energy Technology Data Exchange (ETDEWEB)

    Keunecke, M., E-mail: martin.keunecke@ist.fraunhofer.d [Fraunhofer Institute for Surface Engineering and Thin Films (IST), Braunschweig (Germany); Weigel, K.; Bewilogua, K. [Fraunhofer Institute for Surface Engineering and Thin Films (IST), Braunschweig (Germany); Cremer, R.; Fuss, H.-G. [CemeCon AG, Wuerselen (Germany)

    2009-12-31

    Amorphous hydrogenated carbon (a-C:H) coatings are widely used in several industrial applications. These coatings commonly will be prepared by plasma activated chemical vapor deposition (PACVD). The main method used to prepare a-C:H coating in industrial scale is based on a glow discharge in a hydrocarbon gas like acetylene or methane using a substrate electrode powered with medium frequency (m.f. - some 10 to 300 kHz). Some aims of further development are adhesion improvement, increase of hardness and high coating quality on complex geometries. A relatively new and promising technique to fulfil these requirements is the deposition of a-C:H coatings by a reactive d.c. magnetron sputter deposition from a graphite target with acetylene as reactive gas. An advancement of this technique is the deposition in a pulsed magnetron sputter process. Using these three mentioned techniques a-C:H coatings were prepared in the same deposition machine. For adhesion improvement different interlayer systems were applied. The effect of different substrate bias voltages (d.c. and d.c. pulse) was investigated. By applying the magnetron sputter technique in the d.c. pulse mode, plastic hardness values up to 40 GPa could be reached. Besides hardness other mechanical properties like resistance against abrasive wear were measured and compared. Cross sectional SEM images showed the growth structure of the coatings.

  13. The impact of hybrid energy storage on power quality, when high power pulsed DC loads are operated on a microgrid testbed

    Science.gov (United States)

    Kelley, Jay Paul

    . This enables the generator to maintain its operation at levels of high efficiency thereby increasing the power quality of the AC bus. The work discussed here is aimed at evaluating how the use of energy storage impacts the power quality on MicroGrid's AC bus when high rate DC and AC loads are sourced simultaneously. Also HESM has been developed and evaluated as a mean to optimizing both the power and energy density of the energy storage installed.

  14. Nutritional and anti-nutritional potential of three accessions of itching bean (Mucuna pruriens (L.) DC var. pruriens): an under-utilized tribal pulse.

    Science.gov (United States)

    Kala, Balasubiramanian Kamatchi; Mohan, Veerabahu Ramasamy

    2010-08-01

    Three accessions of the under-utilized legume itching bean (Mucuna pruriens var. pruriens) were analysed for proximate composition, mineral profiles, vitamins (niacin and ascorbic acid), fatty acid profiles, amino acid profiles of total seed protein, in vitro protein digestibility and certain anti-nutritional factors. All three accessions of M. pruriens var. pruriens contained higher amounts of crude protein and crude lipid when compared with most of the commonly consumed pulses. The fatty acid profiles revealed that the seed lipids contained a higher concentration of palmitic acid and linoleic acids. Amino acid profiles of M. pruriens var. pruriens revealed that the seed protein contained relatively higher levels of certain essential amino acids compared with the FAO/WHO requirement pattern. The investigated seeds are rich in minerals such as potassium, calcium, magnesium, phosphorus, iron and manganese. Anti nutritional substances such as total free phenolics, tannins, 3,4-dihydroxyphenylalanine, phytic acid, hydrogen cyanide, trypsin inhibitor activity, oligosaccharides and phytohaemagglutinating activity were investigated. The anti-nutritional fatty acid, behenic acid, also was detected in the present study.

  15. Improved irradiation tolerance of reactive gas pulse sputtered TiN coatings with a hybrid architecture of multilayered and compositionally graded structures

    Science.gov (United States)

    Liang, Wei; Yang, Jijun; Zhang, Feifei; Lu, Chenyang; Wang, Lumin; Liao, Jiali; Yang, Yuanyou; Liu, Ning

    2018-04-01

    This study investigates the improved irradiation tolerance of reactive gas pulse (RGP) sputtered TiN coatings which has hybrid architecture of multilayered and compositionally graded structures. The multilayered RGP-TiN coating is composed of hexagonal close-packed Ti phase and face-centred cubic TiN phase sublayers, where the former sublayer has a compositionally graded structure and the latter one maintains constant stoichiometric atomic ratio of Ti:N. After 100 keV He ion irradiation, the RGP-TiN coating exhibits improved irradiation resistance compared with its single layered (SL) counterpart. The size and density of He bubbles are smaller in the RGP-TiN coating than in the SL-TiN coating. The irradiation-induced surface blistering of the coatings shows a similar tendency. Meanwhile, the irradiation hardening and adhesion strength of the RGP-TiN coatings were not greatly affected by He irradiation. Moreover, the irradiation damage tolerance of the coatings can be well tuned by changing the undulation period number of N2 gas flow rate. Detailed analysis suggested that this improved irradiation tolerance could be related to the combined contribution of the multilayered and compositionally graded structures.

  16. Epitaxial growth of indium oxyfluoride thin films by reactive pulsed laser deposition: Structural change induced by fluorine insertion into vacancy sites in bixbyite structure

    Energy Technology Data Exchange (ETDEWEB)

    Okazaki, Sohei [Kanagawa Academy of Science and Technology (KAST), 3-2-1 Sakado, Takatsu-ku, Kawasaki 213-0012 (Japan); CREST, Japan Science and Technology Agency (JST), 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Hirose, Yasushi, E-mail: hirose@chem.s.u-tokyo.ac.jp [Kanagawa Academy of Science and Technology (KAST), 3-2-1 Sakado, Takatsu-ku, Kawasaki 213-0012 (Japan); CREST, Japan Science and Technology Agency (JST), 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Department of Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Nakao, Shoichiro [Kanagawa Academy of Science and Technology (KAST), 3-2-1 Sakado, Takatsu-ku, Kawasaki 213-0012 (Japan); CREST, Japan Science and Technology Agency (JST), 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Yang, Chang [Kanagawa Academy of Science and Technology (KAST), 3-2-1 Sakado, Takatsu-ku, Kawasaki 213-0012 (Japan); CREST, Japan Science and Technology Agency (JST), 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Department of Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Harayama, Isao; Sekiba, Daiichiro [Tandem Accelerator Complex, University of Tsukuba, Tennodai 1-1-1, Tsukuba, Ibaraki 305-8577 (Japan); Hasegawa, Tetsuya [Kanagawa Academy of Science and Technology (KAST), 3-2-1 Sakado, Takatsu-ku, Kawasaki 213-0012 (Japan); CREST, Japan Science and Technology Agency (JST), 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Department of Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)

    2014-05-30

    InO{sub x}F{sub y} thin films were epitaxially grown on Y-stabilized ZrO{sub 2} (111) substrates by reactive pulsed laser deposition. By changing the substrate temperature (T{sub S}), we were able to control the fluorine content of the film. Phase-pure epitaxial thin films with bixbyite-like ordering in the anion-site occupancy were obtained at high T{sub S} (≥ 240 °C), where fluorine was inserted into the vacancy sites in the bixbyite lattice up to y / (x + y) ∼ 0.3. By decreasing T{sub S}, y / (x + y) increased and the bixbyite-like ordering disappeared; simultaneously, fluorine-rich and fluorine-poor subphases emerged. The films grown at T{sub S} ≤ 150 °C were amorphous and exhibited higher optical absorbance and electrical resistivity than the epitaxial films. - Highlights: • InO{sub x}F{sub y} epitaxial thin films with high fluorine concentration were grown on Y:ZrO{sub 2}. • Anion composition and structural, optical and transport properties were studied. • Fluorine is topotactically inserted into the oxygen vacancy sites in bixbyite cell. • Bixbyite-like ordering of the anion site occupancy was conserved in y / (x + y) ≤ ∼ 0.3.

  17. Epitaxial growth of indium oxyfluoride thin films by reactive pulsed laser deposition: Structural change induced by fluorine insertion into vacancy sites in bixbyite structure

    International Nuclear Information System (INIS)

    Okazaki, Sohei; Hirose, Yasushi; Nakao, Shoichiro; Yang, Chang; Harayama, Isao; Sekiba, Daiichiro; Hasegawa, Tetsuya

    2014-01-01

    InO x F y thin films were epitaxially grown on Y-stabilized ZrO 2 (111) substrates by reactive pulsed laser deposition. By changing the substrate temperature (T S ), we were able to control the fluorine content of the film. Phase-pure epitaxial thin films with bixbyite-like ordering in the anion-site occupancy were obtained at high T S (≥ 240 °C), where fluorine was inserted into the vacancy sites in the bixbyite lattice up to y / (x + y) ∼ 0.3. By decreasing T S , y / (x + y) increased and the bixbyite-like ordering disappeared; simultaneously, fluorine-rich and fluorine-poor subphases emerged. The films grown at T S ≤ 150 °C were amorphous and exhibited higher optical absorbance and electrical resistivity than the epitaxial films. - Highlights: • InO x F y epitaxial thin films with high fluorine concentration were grown on Y:ZrO 2 . • Anion composition and structural, optical and transport properties were studied. • Fluorine is topotactically inserted into the oxygen vacancy sites in bixbyite cell. • Bixbyite-like ordering of the anion site occupancy was conserved in y / (x + y) ≤ ∼ 0.3

  18. Interface description using computational methods and tribological characteristic of Ti N/Ti C films prepared by reactive pulse arc evaporation technique

    International Nuclear Information System (INIS)

    Devia N, D. M.; Gonzalez C, J. M.; Ruden M, A.

    2013-01-01

    The Ti N/Ti C bilayers have been deposited by Plasma Assisted Physical Vapor Deposition Technique - Reactive Pulsed Arc. The coatings were analyzed by X-ray photoelectron spectroscopy (XP S) and X-ray diffraction (XRD). From the signal treatment of the narrow XP S spectra and the XRD diffraction patterns, the formation of Ti N (titanium nitride), Ti C (titanium carbide) and Ti CN (titanium carbonitride) was confirmed, with fm-3m spatial group, corresponding to the Fcc phase of the synthesized compounds. The multilayer was simulated using Density Functional Theory (DFT) by the Unrestricted Hartree Fock method. Charge distributions and electron total density were obtained; finding bond formation at the interphase, electrical neutrality and system stability. Anomalies in the corners of the structures due to edge effect, simulation ideality and the no internal tension inclusion, intrinsic to the growing, are observed. The ball on disc tribometer was used to measure the friction and wear coefficient to verify the interface formation. (Author)

  19. Interface description using computational methods and tribological characteristic of Ti N/Ti C films prepared by reactive pulse arc evaporation technique

    Energy Technology Data Exchange (ETDEWEB)

    Devia N, D. M. [Universidad Nacional de Colombia, Sede Manizales, Campus La Nubia, Manizales, Caldas (Colombia); Gonzalez C, J. M.; Ruden M, A., E-mail: dmdevian@utp.edu.co [Universidad del Valle, Edificio 349, espacio 1003, Ciudad Universitaria Melendez, Cali (Colombia)

    2013-10-01

    The Ti N/Ti C bilayers have been deposited by Plasma Assisted Physical Vapor Deposition Technique - Reactive Pulsed Arc. The coatings were analyzed by X-ray photoelectron spectroscopy (XP S) and X-ray diffraction (XRD). From the signal treatment of the narrow XP S spectra and the XRD diffraction patterns, the formation of Ti N (titanium nitride), Ti C (titanium carbide) and Ti CN (titanium carbonitride) was confirmed, with fm-3m spatial group, corresponding to the Fcc phase of the synthesized compounds. The multilayer was simulated using Density Functional Theory (DFT) by the Unrestricted Hartree Fock method. Charge distributions and electron total density were obtained; finding bond formation at the interphase, electrical neutrality and system stability. Anomalies in the corners of the structures due to edge effect, simulation ideality and the no internal tension inclusion, intrinsic to the growing, are observed. The ball on disc tribometer was used to measure the friction and wear coefficient to verify the interface formation. (Author)

  20. Effect of deposition temperature on the properties of Al-doped ZnO films prepared by pulsed DC magnetron sputtering for transparent electrodes in thin-film solar cells

    Science.gov (United States)

    Kim, Doo-Soo; Park, Ji-Hyeon; Shin, Beom-Ki; Moon, Kyeong-Ju; Son, Myoungwoo; Ham, Moon-Ho; Lee, Woong; Myoung, Jae-Min

    2012-10-01

    A simple but scalable approach to the production of surface-textured Al-doped ZnO(AZO) films for low-cost transparent electrode applications in thin-film solar cells is introduced in this study by combining pulsed dc magnetron sputtering (PDMS) with wet etching in sequence. First, structural, electrical, and optical properties of the AZO films prepared by a PDMS were investigated as functions of deposition temperature to obtain transparent electrode films that can be used as indium-free alternative to ITO electrodes. Increase in the deposition temperature to 230 °C accompanied the improvement in crystalline quality and doping efficiency, which enabled the lowest electrical resistivity of 4.16 × 10-4 Ω cm with the carrier concentration of 1.65 × 1021 cm-3 and Hall mobility of 11.3 cm2/V s. The wet etching of the films in a diluted HCl solution resulted in surface roughening via the formation of crater-like structures without significant degradation in the electrical properties, which is responsible for the enhanced light scattering capability required for anti-reflective electrodes in thin film solar cells.

  1. Effect of a Ga-doped ZnO thin film with a ZTO buffer layer fabricated by using pulsed DC magnetron sputter for dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Song, Sang-Woo; Lee, Kyung-Ju; Roh, Ji-Hyung; Park, On-Jeon; Kim, Hwan-Sun; Moon, Byung-Moo [Korea University, Seoul (Korea, Republic of); Ji, Min-Woo [Yonsei University, Seoul (Korea, Republic of)

    2014-08-15

    The electrical property of a Ga-doped ZnO(GZO) thin film is well known to be similar that of commercialized fluorine-doped tin oxide(FTO). However GZO is limited for use at high process temperatures for solar cells because of its unstable resistivity at temperatures above 300 .deg. C. A GZO thin film compared to zinc tin oxide(ZTO)-GZO multilayer can be used at high process temperatures. A GZO thin film was deposited on glass by using pulsed DC magnetron sputter. Then, a ZTO buffer layer was deposited on the GZO surface. During the deposition, the working pressure was 5 mTorr (Z-1 glass) and 1 mTorr (Z-2 glass). Dye-sensitized solar cells (DSSCs) were fabricated using Z-1, Z-2 and commercialized FTO glasses. Z-2 showed a conversion efficiency of 4.265%, which was enhanced by 0.399% compared to that of the DSSCs using FTO(3.784%). The conversion efficiency for Z-1 (3.889%) was a little higher than that of FTO. Thus, the ZTO-GZO electrode showed better characteristics than those obtained using the FTO electrode, which can be attributed to the reduced charge recombination and series resistance.

  2. DC Home Appliances for DC Distribution System

    Directory of Open Access Journals (Sweden)

    MUHAMMAD KAMRAN

    2017-10-01

    Full Text Available This paper strengthens the idea of DC distribution system for DC microgrid consisting of a building of 50 apartments. Since the war of currents AC system has been dominant because of the paucity of research in the protection of the DC system. Now with the advance research in power electronics material and components, generation of electricity is inherently DC as by solar PV, fuel cell and thermoelectric generator that eliminates the rectification process. Transformers are replaced by the power electronics buck-boost converters. DC circuit breakers have solved the protection problems for both DC transmission and distribution system. In this paper 308V DC microgrid is proposed and home appliances (DC internal are modified to operate on 48V DC from DC distribution line. Instead of using universal and induction motors in rotary appliances, BLDC (Brushless DC motors are proposed that are highly efficient with minimum electro-mechanical and no commutation losses. Proposed DC system reduces the power conversion stages, hence diminishes the associated power losses and standby losses that boost the overall system efficiency. So in view of all this a conventional AC system can be replaced by a DC system that has many advantages by cost as well as by performance

  3. ELECTRICAL PROPERTIES OF DC REACTIVE MAGNETRON ...

    African Journals Online (AJOL)

    Mgina

    value of the AC resistivity was given by the ZnO:Al film with the highest value of ... Compared to other thin film ... critical parameters in determining the ... approach in studying the electronic transport ..... J 2009 Electrical and optical studies of.

  4. The application of standardized control and interface circuits to three dc to dc power converters.

    Science.gov (United States)

    Yu, Y.; Biess, J. J.; Schoenfeld, A. D.; Lalli, V. R.

    1973-01-01

    Standardized control and interface circuits were applied to the three most commonly used dc to dc converters: the buck-boost converter, the series-switching buck regulator, and the pulse-modulated parallel inverter. The two-loop ASDTIC regulation control concept was implemented by using a common analog control signal processor and a novel digital control signal processor. This resulted in control circuit standardization and superior static and dynamic performance of the three dc-to-dc converters. Power components stress control, through active peak current limiting and recovery of switching losses, was applied to enhance reliability and converter efficiency.

  5. Step-Up DC-DC converters

    DEFF Research Database (Denmark)

    Forouzesh, Mojtaba; Siwakoti, Yam P.; Gorji, Saman A.

    2017-01-01

    on the general law and framework of the development of next-generation step-up dc-dc converters, this paper aims to comprehensively review and classify various step-up dc-dc converters based on their characteristics and voltage-boosting techniques. In addition, the advantages and disadvantages of these voltage......DC-DC converters with voltage boost capability are widely used in a large number of power conversion applications, from fraction-of-volt to tens of thousands of volts at power levels from milliwatts to megawatts. The literature has reported on various voltage-boosting techniques, in which......-boosting techniques and associated converters are discussed in detail. Finally, broad applications of dc-dc converters are presented and summarized with comparative study of different voltage-boosting techniques....

  6. Reactive dual magnetron sputtering for large area application

    International Nuclear Information System (INIS)

    Struempfel, J.

    2002-01-01

    Production lines for large area coating demand high productivity of reactive magnetron sputtering processes. Increased dynamic deposition rates for oxides and nitrides were already obtained by using of highly powered magnetrons in combination with advanced sputter techniques. However, besides high deposition rates the uniformity of such coatings has to be carefully considered. First the basics of reactive sputtering processes and dual magnetron sputtering are summarized. Different methods for process stabilization and control are commonly used for reactive sputtering. The Plasma Emission Monitor (PE M) offers the prerequisite for fast acting process control derived from the in-situ intensity measurements of a spectral line of the sputtered target material. Combined by multiple Plasma Emission Monitor control loops segmented gas manifolds are able to provide excellent thin film uniformity at high deposition rates. The Dual Magnetron allows a broad range of processing by different power supply modes. Medium frequency, DC and pulsed DC power supplies can be used for high quality layers. Whereas the large area coating of highly isolating layers like TiO 2 or SiO 2 is dominated by MF sputtering best results for coating with transparent conductive oxides are obtained by dual DC powering of the dual magnetron arrangement. (Author)

  7. Hierarchical Velocity Control Based on Differential Flatness for a DC/DC Buck Converter-DC Motor System

    Directory of Open Access Journals (Sweden)

    R. Silva-Ortigoza

    2014-01-01

    Full Text Available This paper presents a hierarchical controller that carries out the angular velocity trajectory tracking task for a DC motor driven by a DC/DC Buck converter. The high level control is related to the DC motor and the low level control is dedicated to the DC/DC Buck converter; both controls are designed via differential flatness. The high level control provides a desired voltage profile for the DC motor to achieve the tracking of a desired angular velocity trajectory. Then, a low level control is designed to ensure that the output voltage of the DC/DC Buck converter tracks the voltage profile imposed by the high level control. In order to experimentally verify the hierarchical controller performance, a DS1104 electronic board from dSPACE and Matlab-Simulink are used. The switched implementation of the hierarchical average controller is accomplished by means of pulse width modulation. Experimental results of the hierarchical controller for the velocity trajectory tracking task show good performance and robustness against the uncertainties associated with different system parameters.

  8. DC electric springs with DC/DC converters

    DEFF Research Database (Denmark)

    Wang, Qingsong; Cheng, Ming; Jiang, Yunlei

    2016-01-01

    The concept of DC electric spring (DCES) was recently proposed to solve the stability issue caused by integrating intermittent renewable energy sources (RESs) to DC microgrids. In this paper, a new topology of DCES is proposed based on DC/DC converters. The proposed DCES consists of a bi-directio......The concept of DC electric spring (DCES) was recently proposed to solve the stability issue caused by integrating intermittent renewable energy sources (RESs) to DC microgrids. In this paper, a new topology of DCES is proposed based on DC/DC converters. The proposed DCES consists of a bi...... and/or constant discharging for batteries is adopted and four operating modes are analyzed as charging-positive, charging-negative, discharging-positive and discharging-negative modes. An additional mechanism for fast charging or fast discharging is also designed to secure normal operation...... of batteries. With the proposed DCES, the power fluctuations due to intermittent RESs can be passed to non-critical loads (NCLs) and batteries while power on critical loads (CLs) is kept stable. This is possibly the first attempt to design a DCES with only DC/DC converters. The performances of the proposed...

  9. Effect of Ta buffer and NiFe seed layers on pulsed-DC magnetron sputtered Ir{sub 20}Mn{sub 80}/Co{sub 90}Fe{sub 10} exchange bias

    Energy Technology Data Exchange (ETDEWEB)

    Oksuezoglu, Ramis Mustafa, E-mail: rmoksuzoglu@anadolu.edu.t [University of Anadolu, Faculty of Engineering and Architecture, Department of Materials Sciences and Engineering, Iki Eyluel Campus, 26555 Eskisehir (Turkey); Yildirim, Mustafa; Cinar, Hakan [University of Anadolu, Faculty of Engineering and Architecture, Department of Materials Sciences and Engineering, Iki Eyluel Campus, 26555 Eskisehir (Turkey); Hildebrandt, Erwin; Alff, Lambert [Department of Materials Sciences, Darmstadt University of Technology, Petersenstrasse 23, D-64287 Darmstadt (Germany)

    2011-07-15

    A systematic investigation has been done on the correlation between texture, grain size evolution and magnetic properties in Ta/Ni{sub 81}Fe{sub 19}/Ir{sub 20}Mn{sub 80}/Co{sub 90}Fe{sub 10}/Ta exchange bias in dependence of Ta buffer and NiFe seed layer thickness in the range of 2-10 nm, deposited by pulsed DC magnetron sputtering technique. A strong dependence of <1 1 1> texture on the Ta/NiFe thicknesses was found, where the reducing and increasing texture was correlated with exchange bias field and unidirectional anisotropy energy constant at both NiFe/IrMn and IrMn/CoFe interfaces. However, a direct correlation between average grain size in IrMn and H{sub ex} and H{sub c} was not observed. L1{sub 2} phase IrMn{sub 3} could be formed by thickness optimization of Ta/NiFe layers by deposition at room temperature, for which the maximum exchange coupling parameters were achieved. We conclude finally that the coercivity is mainly influenced by texture induced interfacial effects at NiFe/IrMn/CoFe interfaces developing with Ta/NiFe thicknesses. - Research highlights: We discussed the influence of Ta/NiFe thicknesses on structure and grain size in AF layer and texture. A direct correlation between the <1 1 1> texture and exchange coupling was found. A direct relation between average grain size and H{sub ex} and H{sub c} was not observed. L1{sub 2} phase IrMn{sub 3} was formed by deposition at room temperature for Ta (5-6 nm)/NiFe (6-8 nm). We conclude that the coercivity is influenced by order/disorder at NiFe/IrMn/CoFe interfaces.

  10. Effect of deposition temperature on the properties of Al-doped ZnO films prepared by pulsed DC magnetron sputtering for transparent electrodes in thin-film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Doo-Soo; Park, Ji-Hyeon; Shin, Beom-Ki; Moon, Kyeong-Ju [Information and Electronic Materials Research Laboratory, Department of Materials Science and Engineering, Yonsei University, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Son, Myoungwoo [Department of Nanobio Materials and Electronics, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of); Ham, Moon-Ho [Department of Nanobio Materials and Electronics, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of); School of Materials Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of); Lee, Woong [School of Nano and Advanced Materials Engineering, Changwon National University, 9 Sarim-Dong, Changwon, Gyeongnam 641-773 (Korea, Republic of); Myoung, Jae-Min, E-mail: jmmyoung@yonsei.ac.kr [Information and Electronic Materials Research Laboratory, Department of Materials Science and Engineering, Yonsei University, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-749 (Korea, Republic of)

    2012-10-15

    Highlights: Black-Right-Pointing-Pointer Surface-textured AZO films were achieved by combining PDMS method with wet etching. Black-Right-Pointing-Pointer The AZO film deposited at 230 Degree-Sign C by PDMS exhibited the best performance. Black-Right-Pointing-Pointer It is due to the higher plasma density supplied from PDMS system. Black-Right-Pointing-Pointer Wet etching of the films produces a crater-like rough surface morphology. - Abstract: A simple but scalable approach to the production of surface-textured Al-doped ZnO(AZO) films for low-cost transparent electrode applications in thin-film solar cells is introduced in this study by combining pulsed dc magnetron sputtering (PDMS) with wet etching in sequence. First, structural, electrical, and optical properties of the AZO films prepared by a PDMS were investigated as functions of deposition temperature to obtain transparent electrode films that can be used as indium-free alternative to ITO electrodes. Increase in the deposition temperature to 230 Degree-Sign C accompanied the improvement in crystalline quality and doping efficiency, which enabled the lowest electrical resistivity of 4.16 Multiplication-Sign 10{sup -4} {Omega} cm with the carrier concentration of 1.65 Multiplication-Sign 10{sup 21} cm{sup -3} and Hall mobility of 11.3 cm{sup 2}/V s. The wet etching of the films in a diluted HCl solution resulted in surface roughening via the formation of crater-like structures without significant degradation in the electrical properties, which is responsible for the enhanced light scattering capability required for anti-reflective electrodes in thin film solar cells.

  11. Effect of deposition temperature on the properties of Al-doped ZnO films prepared by pulsed DC magnetron sputtering for transparent electrodes in thin-film solar cells

    International Nuclear Information System (INIS)

    Kim, Doo-Soo; Park, Ji-Hyeon; Shin, Beom-Ki; Moon, Kyeong-Ju; Son, Myoungwoo; Ham, Moon-Ho; Lee, Woong; Myoung, Jae-Min

    2012-01-01

    Highlights: ► Surface-textured AZO films were achieved by combining PDMS method with wet etching. ► The AZO film deposited at 230 °C by PDMS exhibited the best performance. ► It is due to the higher plasma density supplied from PDMS system. ► Wet etching of the films produces a crater-like rough surface morphology. - Abstract: A simple but scalable approach to the production of surface-textured Al-doped ZnO(AZO) films for low-cost transparent electrode applications in thin-film solar cells is introduced in this study by combining pulsed dc magnetron sputtering (PDMS) with wet etching in sequence. First, structural, electrical, and optical properties of the AZO films prepared by a PDMS were investigated as functions of deposition temperature to obtain transparent electrode films that can be used as indium-free alternative to ITO electrodes. Increase in the deposition temperature to 230 °C accompanied the improvement in crystalline quality and doping efficiency, which enabled the lowest electrical resistivity of 4.16 × 10 −4 Ω cm with the carrier concentration of 1.65 × 10 21 cm −3 and Hall mobility of 11.3 cm 2 /V s. The wet etching of the films in a diluted HCl solution resulted in surface roughening via the formation of crater-like structures without significant degradation in the electrical properties, which is responsible for the enhanced light scattering capability required for anti-reflective electrodes in thin film solar cells.

  12. A resonant dc-dc power converter assembly

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention relates to a resonant DC-DC power converter assembly comprising a first resonant DC-DC power converter and a second resonant DC-DC power converter having identical circuit topologies. A first inductor of the first resonant DC-DC power converter and a second inductor of the s......The present invention relates to a resonant DC-DC power converter assembly comprising a first resonant DC-DC power converter and a second resonant DC-DC power converter having identical circuit topologies. A first inductor of the first resonant DC-DC power converter and a second inductor...... of the second resonant DC-DC power converter are configured for magnetically coupling the first and second resonant DC-DC power converters to each other to forcing substantially 180 degrees phase shift, or forcing substantially 0 degree phase shift, between corresponding resonant voltage waveforms of the first...

  13. High power pulsed magnetron sputtering of transparent conducting oxides

    International Nuclear Information System (INIS)

    Sittinger, V.; Ruske, F.; Werner, W.; Jacobs, C.; Szyszka, B.; Christie, D.J.

    2008-01-01

    High power pulsed magnetron sputtering (HPPMS) has been used in order to study the deposition of transparent conducting oxides. We summarize the studies carried out on different materials (indium tin oxide-ITO and aluminium-doped zinc oxide-AZO) using rather different technological approaches, namely sputtering of ceramic targets and reactive sputtering. For the deposition of AZO reactive HPPMS for metallic targets has been used. A feedback control loop has been implemented in order to stabilize the discharge at any given setpoint on the hysteresis curve. The hysteresis was also found to have a rather untypical form. Reactive HPPMS was found to be a promising tool for obtaining high quality films of low total thickness. In the case of ITO deposition a ceramic target has been used. The process has been characterized in terms of its plasma emission and increasing indium ionization was found for higher peak power densities. The properties of the deposited films were compared to DC sputtered films. While for DC sputtering the choice of oxygen addition and shieldings is crucial for determining surface morphology and resistivity, in HPPMS sputtering peak power density has been found to be a good parameter for influencing the crystal structure. The morphologies obtained differ strongly from those seen in DC sputtering. At high power densities films with low surface roughness and excellent resistivity could be deposited without the use of shieldings

  14. Effect of electroless nickel interlayer on the electrochemical behavior of single layer CrN, TiN, TiAlN coatings and nanolayered TiAlN/CrN multilayer coatings prepared by reactive dc magnetron sputtering

    International Nuclear Information System (INIS)

    Grips, V.K. William; Ezhil Selvi, V.; Barshilia, Harish C.; Rajam, K.S.

    2006-01-01

    The electrochemical behavior of single layer TiN, CrN, TiAlN and multilayer TiAlN/CrN coatings, deposited on steel substrates using a multi-target reactive direct current (dc) magnetron sputtering process, was studied in 3.5% NaCl solution. The total thickness of the coatings was about 1.5 μm. About 0.5 μm thick chromium interlayer was used to improve adhesion of the coatings. With an aim to improve the corrosion resistance, an additional interlayer of approximately 5 μm thick electroless nickel (EN) was deposited on the substrate. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were used to study the corrosion behavior of the coatings. Scanning electron microscopy and energy dispersive X-ray analysis were used to characterize the corroded samples. The potentiodynamic polarization tests showed lower corrosion current density and higher polarization resistance (R p ) for the coatings with EN interlayer. For example, the corrosion current density of TiN coated steel was decreased by a factor of 10 by incorporating 5 μm thick EN interlayer. Similarly, multilayer coatings of TiAlN/CrN with EN interlayer showed about 30 times improved corrosion resistance as compared to the multilayers without EN interlayer. The porosity values were calculated from the potentiodynamic polarization data. The Nyquist and the Bode plots obtained from the EIS data were fitted by appropriate equivalent circuits. The pore resistance (R pore ), the charge transfer resistance (R ct ), the coating capacitance (Q coat ) and the double layer capacitance (Q dl ) of the coatings were obtained from the equivalent circuit. Multilayer coatings showed higher R pore and R ct values as compared to the single layer coatings. Similarly, the Q coat and Q dl values decreased from uncoated substrate to the multilayer coatings, indicating a decrease in the defect density by the addition of EN interlayer. These studies were confirmed by examining the corroded samples under

  15. IGBT Based DC/DC Converter

    Directory of Open Access Journals (Sweden)

    M. Akherraz

    1997-12-01

    Full Text Available This paper presents an in-depth analytical and experimental investigation of an indirect DC-DC converter. The DC-AC conversion is a full bridge based on IGBT power modules, and the AC-DC conversion is done via a high  frequency AC link and a first diode bridge. The AC link, which consists of snubbing capacitors and a variable air-gap transformer, is analytically designed to fulfill Zero Voltage commutation requirement. The proposed converter is simulated using PSPICE and a prototype is designed built and tested in the laboratory. PSPICE simulation and experimental results are presented and compared.

  16. Analog Fiber Optic Link with DC-100 MHz Bandwidth

    National Research Council Canada - National Science Library

    Sullivan, C. A; Girardi, P. G; Lohrmann, Dieter R

    2008-01-01

    An analog fiber optic link covering the frequency range from DC to 100 MHz was designed, constructed, and tested, in order to connect a 10 kA pulse current probe to oscilloscopes for oscillographing...

  17. Computerized Torque Control for Large dc Motors

    Science.gov (United States)

    Willett, Richard M.; Carroll, Michael J.; Geiger, Ronald V.

    1987-01-01

    Speed and torque ranges in generator mode extended. System of shunt resistors, electronic switches, and pulse-width modulation controls torque exerted by large, three-phase, electronically commutated dc motor. Particularly useful for motor operating in generator mode because it extends operating range to low torque and high speed.

  18. A resonant dc-dc power converter assembly

    OpenAIRE

    Madsen, Mickey Pierre

    2015-01-01

    The present invention relates to a resonant DC-DC power converter assembly comprising a first resonant DC-DC power converter and a second resonant DC-DC power converter having identical circuit topologies. A first inductor of the first resonant DC-DC power converter and a second inductor of the second resonant DC-DC power converter are configured for magnetically coupling the first and second resonant DC-DC power converters to each other to forcing substantially 180 degrees phase shift, or fo...

  19. Studies on the cross-magnetron effect in the reactive indium tin oxide deposition. Effects of an inhomogeneous plasma distribution on the coating properties in dynamic and static coating by means of a pulsed dual magnetron

    International Nuclear Information System (INIS)

    Kleinhempel, Ronny

    2008-01-01

    In the present thesis the reactive ITO deposition process under application of metallic In:Sn targets is intensively studied. The coating deposition pursues at a symmetric bipolarly pulsed dual magnetron both on resting and moving substrates. The thesis comprehends two partial fields. On the one hand the dynamic deposition process was comprehensively characterized at an near-industry test facility and successfully transformed by means of its physical parameters to an industrial coating facility. On the other hand static depositions were performed. These allow the analysis of the lateral distribution of the functional coating properties. By this a correlation to the lateral distributions of the measured plasma parameters could be elaborated [de

  20. Troubleshooting of Modulator DC power supply at KOMAC

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Hae Seong; Kim, Han Sung; Kwon, Hyeok Jung; Kim, Seong Gu; Kim, Dae Il; Lee, Seok Geun; Kim, Jae Ha; Seol, Kyeong Tae; Cho, Yong Sub [KAERI, Daejeon (Korea, Republic of)

    2016-05-15

    The process of solving problems to operate the 2nd converter modulator will be introduced. Also, the PSpice simulation result about the 12-pulse rectifier will be compared with the measurement result. KOMAC (KOrea Multi-purpose Accelerator Complex) has four HVCMs (High Voltage Converter Modulator) which are the power source of nine klystrons. Four HVCMs are already operated since 2013 for operating the 100 MeV linear proton accelerator at KOMAC. This HVCM system includes the 12-pulse rectifier (ac-dc), capacitors bank (dc-link, Pos, Neg) and converter modulator (dc-dc). Especially, the 12-pulse rectifier system receives the power from the utility and converts 3,300 ac voltage to 2,200 dc voltage for supplying the dc power to the capacitors bank. This rectifier system used twelve thyristors for the rectification and applied RC snubber networks to protect the semiconductor switches (thyristors). Since the 2nd modulator dc power supply has troubled, the troubleshooting process conducted by the staves of KOMAC. It takes 3 months to solve the problems because it is not easy to find the faulty wiring. Nevertheless, our staves found the faulty point with a hope to operate the modulator system and the PSpice simulation helps to solve the problems. Using PSpice which is tool for simulating the circuit, the dc power supply abnormal phenomenon was simulated exactly. After corrected the faulty wiring, the modulator dc power supply operated.

  1. Egr2 induced during DC development acts as an intrinsic negative regulator of DC immunogenicity.

    Science.gov (United States)

    Miah, Mohammad Alam; Byeon, Se Eun; Ahmed, Md Selim; Yoon, Cheol-Hee; Ha, Sang-Jun; Bae, Yong-Soo

    2013-09-01

    Early growth response gene 2 (Egr2), which encodes a zinc finger transcription factor, is rapidly and transiently induced in various cell types independently of de novo protein synthesis. Although a role for Egr2 is well established in T-cell development, Egr2 expression and its biological function in dendritic cells (DCs) have not yet been described. Here, we demonstrate Egr2 expression during DC development, and its role in DC-mediated immune responses. Egr2 is expressed in the later stage of DC development from BM precursor cells. Even at steady state, Egr2 is highly expressed in mouse splenic DCs. Egr2-knockdown (Egr2-KD) DCs showed increased levels of major histocompatability complex (MHC) class I and II and co-stimulatory molecules, and enhanced antigen uptake and migratory capacities. Furthermore, Egr2-KD abolished SOCS1 expression and signal transducer and activator of transcription 5 (STAT5) activation during DC development, probably resulting in the enhancement of IL-12 expression and Th1 immunogenicity of a DC vaccine. DC-mediated cytotoxic T lymphocyte (CTL) activation and antitumor immunity were significantly enhanced by Egr2-KD, and impaired by Egr2 overexpression in antigen-pulsed DC vaccines. These data suggest that Egr2 acts as an intrinsic negative regulator of DC immunogenicity and can be an attractive molecular target for DC vaccine development. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Physical model of reactor pulse

    International Nuclear Information System (INIS)

    Petrovic, A.; Ravnik, M.

    2004-01-01

    Pulse experiments have been performed at J. Stefan Institute TRIGA reactor since 1991. In total, more than 130 pulses have been performed. Extensive experimental information on the pulse physical characteristics has been accumulated. Fuchs-Hansen adiabatic model has been used for predicting and analysing the pulse parameters. The model is based on point kinetics equation, neglecting the delayed neutrons and assuming constant inserted reactivity in form of step function. Deficiencies of the Fuchs-Hansen model and systematic experimental errors have been observed and analysed. Recently, the pulse model was improved by including the delayed neutrons and time dependence of inserted reactivity. The results explain the observed non-linearity of the pulse energy for high pulses due to finite time of pulse rod withdrawal and the contribution of the delayed neutrons after the prompt part of the pulse. The results of the improved model are in good agreement with experimental results. (author)

  3. Active superconducting DC fault current limiter based on flux compensation

    International Nuclear Information System (INIS)

    Shi Jing; Tang Yuejin; Wang, Chen; Zhou Yusheng; Li Jingdong; Ren Li; Chen Shijie

    2006-01-01

    With the extensive application of DC power systems, suppression of DC fault current is an important subject that guarantees system security. This paper presents an active superconducting DC fault current limiter (DC-SFCL) based on flux compensation. The DC-SFCL is composed of two superconducting windings wound on a single iron core, the primary winding is in series with DC power system, and the second winding is connected with AC power system through a PWM converter. In normal operating state, the flux in the iron core is compensated to zero, and the SFCL has no influence on DC power system. In the case of DC system accident, through regulating the active power exchange between the SFCL's second winding and the AC power system, the current on the DC side can be limited to different level complying with the system demand. Moreover, the PWM converter that interface the DC system and AC system can be controlled as a reactive power source to supply voltage support for the AC side, which has little influence on the performance of SFCL. Using MATLAB SIMULINK, the mathematic model of the DC-SFCL is created, simulation results validate the dynamics of system, and the performance of DC-SFCL is confirmed

  4. Giant Negative Piezoresistive Effect in Diamond-like Carbon and Diamond-like Carbon-Based Nickel Nanocomposite Films Deposited by Reactive Magnetron Sputtering of Ni Target

    DEFF Research Database (Denmark)

    Meškinis, Šaru Nas; Gudaitis, Rimantas; Šlapikas, Kęstutis

    2018-01-01

    deposited by either reactive HIPIMS or dc magnetron sputtering of Ni target was explained by possible clustering of the sp2-bonded carbon and/or formation of areas with the decreased hydrogen content. It was suggested that the tensile stress-induced rearrangements of these conglomerations have resulted......Piezoresistive properties of hydrogenated diamond-like carbon (DLC) and DLC-based nickel nanocomposite (DLC:Ni) films were studied in the range of low concentration of nickel nanoparticles. The films were deposited by reactive high power pulsed magnetron sputtering (HIPIMS) of Ni target, and some...... samples were deposited by direct current (dc) reactive magnetron sputtering for comparison purposes. Raman scattering spectroscopy, energy-dispersive X-ray spectrometry (EDS), and X-ray photoelectron spectroscopy (XPS) were used to study the structure and chemical composition of the films. A four...

  5. A dc non-thermal atmospheric-pressure plasma microjet

    Science.gov (United States)

    Zhu, WeiDong; Lopez, Jose L.

    2012-06-01

    A direct current (dc), non-thermal, atmospheric-pressure plasma microjet is generated with helium/oxygen gas mixture as working gas. The electrical property is characterized as a function of the oxygen concentration and show distinctive regions of operation. Side-on images of the jet were taken to analyze the mode of operation as well as the jet length. A self-pulsed mode is observed before the transition of the discharge to normal glow mode. Optical emission spectroscopy is employed from both end-on and side-on along the jet to analyze the reactive species generated in the plasma. Line emissions from atomic oxygen (at 777.4 nm) and helium (at 706.5 nm) were studied with respect to the oxygen volume percentage in the working gas, flow rate and discharge current. Optical emission intensities of Cu and OH are found to depend heavily on the oxygen concentration in the working gas. Ozone concentration measured in a semi-confined zone in front of the plasma jet is found to be from tens to ˜120 ppm. The results presented here demonstrate potential pathways for the adjustment and tuning of various plasma parameters such as reactive species selectivity and quantities or even ultraviolet emission intensities manipulation in an atmospheric-pressure non-thermal plasma source. The possibilities of fine tuning these plasma species allows for enhanced applications in health and medical related areas.

  6. A dc non-thermal atmospheric-pressure plasma microjet

    International Nuclear Information System (INIS)

    Zhu Weidong; Lopez, Jose L

    2012-01-01

    A direct current (dc), non-thermal, atmospheric-pressure plasma microjet is generated with helium/oxygen gas mixture as working gas. The electrical property is characterized as a function of the oxygen concentration and show distinctive regions of operation. Side-on images of the jet were taken to analyze the mode of operation as well as the jet length. A self-pulsed mode is observed before the transition of the discharge to normal glow mode. Optical emission spectroscopy is employed from both end-on and side-on along the jet to analyze the reactive species generated in the plasma. Line emissions from atomic oxygen (at 777.4 nm) and helium (at 706.5 nm) were studied with respect to the oxygen volume percentage in the working gas, flow rate and discharge current. Optical emission intensities of Cu and OH are found to depend heavily on the oxygen concentration in the working gas. Ozone concentration measured in a semi-confined zone in front of the plasma jet is found to be from tens to ∼120 ppm. The results presented here demonstrate potential pathways for the adjustment and tuning of various plasma parameters such as reactive species selectivity and quantities or even ultraviolet emission intensities manipulation in an atmospheric-pressure non-thermal plasma source. The possibilities of fine tuning these plasma species allows for enhanced applications in health and medical related areas. (paper)

  7. Performance of 22.4-kW nonlaminated-frame dc series motor with chopper controller. [a dc to dc voltage converter

    Science.gov (United States)

    Schwab, J. R.

    1979-01-01

    Performance data obtained through experimental testing of a 22.4 kW traction motor using two types of excitation are presented. Ripple free dc from a motor-generator set for baseline data and pulse width modulated dc as supplied by a battery pack and chopper controller were used for excitation. For the same average values of input voltage and current, the motor power output was independent of the type of excitation. However, at the same speeds, the motor efficiency at low power output (corresponding to low duty cycle of the controller) was 5 to 10 percentage points lower on chopped dc than on ripple free dc. The chopped dc locked-rotor torque was approximately 1 to 3 percent greater than the ripple free dc torque for the same average current.

  8. Full range ZVS DC-DC converter

    International Nuclear Information System (INIS)

    Upadhyay, Rinki; Badapanda, M.K.; Hannurkar, P.R.

    2011-01-01

    A 500 V, 24 Amp DC-DC converter with digital signal processor (DSP) based control and protection has been designed, fabricated and tested. Its power circuit consists of IGBT based single phase inverter bridge, ferrite transformer and diode rectifier. All IGBTs in the inverter bridge are operated in zero voltage switching (ZVS) mode to minimize switching losses thereby increasing the efficiency of the converter significantly. The efficiency of this converter is measured to be greater than 97% at full load. In a conventional full bridge inverter, typically ZVS is achieved under full load condition while at light load ZVS is lost. An auxiliary LC circuit has been intentionally incorporated in this converter to achieve ZVS even at light loaded conditions. Detailed simulation of the converter circuit is carried out and crucial waveforms have been presented in this paper. Microchip make dsPIC30F2020 DSP is employed to provide phase shifted PWMs to IGBTs in the inverter bridge. All the crucial parameters are also monitored by this DSP and in case of any unfavorable conditions, the converter is tripped off. Suitable experiments were carried out in this DC-DC converter under different loaded conditions and a close match between the simulated and experimental results were obtained. Such DC-DC converters can be connected in series or parallel for the development of solid state modular power supplies for various applications. (author)

  9. Geometry Optimization of DC/RF Photoelectron Gun

    CERN Document Server

    Chen Ping; Yu, David

    2005-01-01

    Pre-acceleration of photoelectrons in a pulsed, high voltage, short, dc gap and its subsequent injection into an rf gun is a promising method to improve electron beam emittance in rf accelerators. Simulation work has been performed in order to optimize the geometric shapes of a dc/rf gun and improve electron beam properties. Variations were made on cathode and anode shapes, dc gap distance, and inlet shape of the rf cavity. Simulations showed that significant improvement on the normalized emittance (< 1 mm-mrad), compared to a dc gun with flat cathode, could be obtained after the geometric shapes of the gun were optimized.

  10. RF and dc desensitized electroexplosive device

    Science.gov (United States)

    Krainiak, John W.; Speaks, Paul D.; Cornett, Michael S.

    1989-07-01

    This patent application relates to electroexplosive devices (EEDs) such as detonators, blasting caps and squibs, in particular to a method and device for desensitizing EEDs to electromagnetic radiation and electrostatic charges with the added ability to desensitize the device to essentially dc currents. An insensitive electroexplosive device to electrically ignite explosive is disclosed. This device is inherently immune to radio frequency (RF) radiation, and also provides protection against dc or very low frequency RF induced by arcing. A central feature is use of zeners and capacitors to form a reactively balanced bridge circuit. When constructed in semiconductor form, as described in this application, the device is capable of incorporation in small caliber ordnance.

  11. High voltage dc cables

    Energy Technology Data Exchange (ETDEWEB)

    Bjustrom, B

    1965-12-01

    How stress distribution in dc cables varies with temperature and stress level, influence of polarity reversals and space charges, and different types of overvoltage to which dc cable may be subjected are discussed. Design problems, especially as related to corrosion protection and to mechanical stress caused by wire armoring during manufacturing and laying, accessories and work done on test methods, and the possibility of designing 400 to 600 kV dc cables for transmitting 2000 to 4000 MW are described.

  12. Additional ion bombardment in PVD processes generated by a superimposed pulse bias voltage

    International Nuclear Information System (INIS)

    Olbrich, W.; Kampschulte, G.

    1993-01-01

    The superimposed pulse bias voltage is a tool to apply an additional ion bombardment during deposition in physical vapour deposition (PVD) processes. It is generated by the combination of a d.c. ground voltage and a higher d.c. pulse voltage. Using a superimposed pulse bias voltage in ion-assisted PVD processes effects an additional all-around ion bombardment on the surface with ions of higher energy. Both metal and reactive or inert-gas ions are accelerated to the surface. The basic principles and important characteristics of this newly developed process such as ion fluxes or deposition rates are shown. Because of pulsing the high voltage, the deposition temperature does not increase much. The adhesion, structure, morphology and internal stresses are influenced by these additional ion impacts. The columnar growth of the deposited films could be suppressed by using the superimposed pulse bias voltage without increasing the deposition temperature. Different metallizations (Cr and Cu) produced by arc and sputter ion plating are investigated. Carbon-fibre-reinforced epoxy are coated with PVD copper films for further treatment in electrochemical processes. (orig.)

  13. Numerical analysis and simulation of behavior of high burn-up PWR fuel pulse-irradiated in reactivity-initiated accident conditions

    International Nuclear Information System (INIS)

    Suzuki, M.; Sugiyama, T.; Udagawa, Y.; Nagase, F.; Fuketa, T.

    2010-01-01

    The four cases of the NSRR experiments, consisting of two room temperature tests and two high temperature tests, using high burn-up PWR fuel rods are analyzed by using the RANNS code to discuss the fuel behavior in hypothetical pulse-irradiation conditions, and the results are compared with metallography observations of ruptured claddings. The cladding rupture occurred by a shear sliding which starts from the tip of incipient crack generated in the hydride dense layer. The analyses reveal that the onset of shear sliding leading to cladding rupture can be closely associated with the stress intensity factor KI at the crack tip and local plastic strain evolution around the tip as well, and that these two factors depend also on the temperature of cladding. Simulation calculations on the basis of experimental conditions reveals that the cladding stress is dependent on the height and half-width of pulse power, and for the same integral enthalpy of pulse a larger half-width mitigates the severity of transient and decreases KI to allow plastic strain by temperature rise, thus failure possibility would be markedly decreased

  14. Obtainment of the subcritical reactivity by mean of measurement of APSD and CPSD employing pulse mode detectors in the IPEN/MB-01 reactor

    International Nuclear Information System (INIS)

    Lee, Seung Min

    2014-01-01

    This work presents a new experimental approach to determine the reactivity levels of subcritical systems. The method employs the subcritical kinetic model developed by Gandini and Salvatores and it is based only on measured quantities such as counting rates of the detectors employed in the experiments and the parameters arising from the least squares fitting of the APSD (Auto Power Spectral Density) and CPSD (Cross Power Spectral Density). Detector efficiencies, quantity required in other procedures such as Neutron Source Multiplication (NSM) method, are not needed in the proposed method. The only hypothesis made in the method was the independence of the effective delayed neutron fraction and the prompt neutron generation time to the subcriticality level of the system. The proposed method was applied to measure the reactivity of several subcritical configurations of the IPEN/MB-01 reactor. Measurements of APSD and CPSD were performed in several degrees of subcriticality (up to around -7000 pcm). The spectral densities data were least squares fitted to get the prompt decay mode (α) and other quantities. Beside the startup source of the facility, an external neutron source of Am-Be was installed near the core in order to improve neutron counting statistics. The final experimental results are of good quality. The proposed experimental method shows clearly that the classical point kinetic theory cannot describe the measured reactivity. Instead, the reactivity inferred from this model follows closely the subcriticality index (ζ) for the source arrangements in the experiment. The agreement of the MCNP5 and GPT-TORT results, both with ENDF/B-VII.0 as the basic nuclear data library, when compared to the corresponding experimental ones was also good. (author)

  15. Microstructure and surface mechanical properties of pulse electrodeposited nickel

    Energy Technology Data Exchange (ETDEWEB)

    Ul-Hamid, A., E-mail: anwar@kfupm.edu.sa [Center of Research Excellence in Corrosion (CoRE-C), Research Institute, King Fahd University of Petroleum and Minerals, P.O. Box 1073, Dhahran 31261 (Saudi Arabia); Dafalla, H.; Quddus, A.; Saricimen, H.; Al-Hadhrami, L.M. [Center of Research Excellence in Corrosion (CoRE-C), Research Institute, King Fahd University of Petroleum and Minerals, P.O. Box 1073, Dhahran 31261 (Saudi Arabia)

    2011-09-01

    The surface of carbon steel was modified by electrochemical deposition of Ni in a standard Watt's bath using dc and pulse plating electrodeposition. The aim was to compare the microstructure and surface mechanical properties of the deposit obtained by both techniques. Materials characterization was conducted using field emission scanning electron microscope fitted with scanning transmission electron detector, atomic force microscope and X-ray diffractometer. Nanoindentation hardness, elastic modulus, adhesion, coefficients of friction and wear rates were determined for both dc and pulse electrodeposits. Experimental results indicate that pulse electrodeposition produced finer Ni grains compared to dc plating. Size of Ni grains increased with deposition. Both dc and pulse deposition resulted in grain growth in preferred (2 0 0) orientation. However, presence of Ni (1 1 1) grains increased in deposits produced by pulse deposition. Pulse plated Ni exhibited higher hardness, creep and coefficient of friction and lower modulus of elasticity compared to dc plated Ni.

  16. Circuit description of unipolar DC-to-DC converters for APS storage ring quadrupoles and sextupoles

    International Nuclear Information System (INIS)

    McGhee, D.G.

    1993-01-01

    This paper describes the control, interlock, and power circuits for 680 unipolar switch mode DC-to-DC converters used to regulate the Advanced Photon Sources (APS's) storage ring quadrupole and sextupole magnet currents. Quadrupole current stability is ± 6x10 -5 and the sextupole current stability is ±3x10 -4 . The stability is obtained with pulse width modulation, operating at a switching frequency of 20kHz with full current switching. The converters are housed in 200 cabinets located on top of the storage ring tunnel. Raw DC power is distributed from 80 AC-to-DC power supplies, four at each of 20 locations around the storage ring. Voltages, currents, and temperatures are computer monitored and logged for the converters and magnets. All converters and magnets are water cooled with the flow and pressure monitored at the inlet and outlet of groups. Water is interlocked with the raw power supplies and not the individual converters

  17. Family of multiport bidirectional DC-DC converters

    NARCIS (Netherlands)

    Tao, H.; Kotsopoulos, A.; Duarte, J.L.; Hendrix, M.A.M.

    2006-01-01

    Multiport DC-DC converters are of potential interest in applications such as generation systems utilising multiple sustainable energy sources. A family of multiport bidirectional DC-DC converters derived from a general topology is presented. The topology shows a combination of DC-link and magnetic

  18. Design and modelling of high gain DC-DC converters for fuel cell hybrid electric vehicles

    Science.gov (United States)

    Elangovan, D.; Karthigeyan, V.; Subhanu, B.; Ashwin, M.; Arunkumar, G.

    2017-11-01

    Transportation (Diesel and petrol internal combustion engine vehicles) approximately contributes to 25.5% of total CO2 emission. Thus diesel and petrol engine vehicles are the most dominant contributors of CO2 emission which leads global warming which causes climate change. The problem of CO2 emission and global warming can be reduced by focusing on renewable energy vehicles. Out of the available renewable energy sources fuel cell is the only source which has reasonable efficiency and can be used in vehicles. But the main disadvantage of fuel cell is its slow response time. So energy storage systems like batteries and super capacitors are used in parallel with the fuel cell. Fuel cell is used during steady state vehicle operation while during transient conditions like starting, acceleration and braking batteries and super capacitors can supply or absorb energy. In this paper a unidirectional fuel cell DC-DC converter and bidirectional energy storage system DC-DC converter is proposed, which can interface dc sources at different voltage levels to the dc bus and also it can independently control the power flow from each energy source to the dc bus and vice versa. The proposed converters are designed and simulated using PSIM version 9.1.1 and gate pulse pattern, input and output voltage waveforms of the converters for steady state operation are studied.

  19. Effect of nitrogen doping on TiO.sub.x./sub.N.sub.y./sub. thin film formation at reactive high-power pulsed magnetron sputtering

    Czech Academy of Sciences Publication Activity Database

    Straňák, Vítězslav; Quaas, M.; Bogdanowicz, R.; Steffen, H.; Wulff, H.; Hubička, Zdeněk; Tichý, M.; Hippler, R.

    2010-01-01

    Roč. 43, č. 28 (2010), s. 1-7 ISSN 0022-3727 R&D Projects: GA AV ČR KAN301370701; GA MŠk(CZ) 1M06002 Grant - others:AVČR(CZ) M100100915 Institutional research plan: CEZ:AV0Z10100522 Keywords : magnetron sputtering * TiO 2 * pulse discharge * XRD * band gap Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.105, year: 2010 http://iopscience.iop.org/0022-3727/43/28/285203/

  20. Programmable dc motor controller

    Science.gov (United States)

    Hopwood, J. E.

    1982-11-01

    A portable programmable dc motor controller, with features not available on commercial instruments was developed for controlling fixtures during welding processes. The controller can be used to drive any dc motor having tachometer feedback and motor requirements not exceeding 30 volts, 3 amperes. Among the controller's features are delayed start time, upslope time, speed, and downslope time.

  1. Multilevel DC link inverter

    Science.gov (United States)

    Su, Gui-Jia

    2003-06-10

    A multilevel DC link inverter and method for improving torque response and current regulation in permanent magnet motors and switched reluctance motors having a low inductance includes a plurality of voltage controlled cells connected in series for applying a resulting dc voltage comprised of one or more incremental dc voltages. The cells are provided with switches for increasing the resulting applied dc voltage as speed and back EMF increase, while limiting the voltage that is applied to the commutation switches to perform PWM or dc voltage stepping functions, so as to limit current ripple in the stator windings below an acceptable level, typically 5%. Several embodiments are disclosed including inverters using IGBT's, inverters using thyristors. All of the inverters are operable in both motoring and regenerating modes.

  2. Influence of the reactive atmosphere on the formation of nanoparticles in the plasma plume induced by nanosecond pulsed laser irradiation of metallic targets at atmospheric pressure and high repetition rate

    Energy Technology Data Exchange (ETDEWEB)

    Girault, M. [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS-Univ. Bourgogne Franche-Comté, 9 Av. A. Savary, BP 47 870, F-21078 Dijon Cedex (France); Le Garrec, J.-L.; Mitchell, J.B.A. [Institut de Physique de Rennes, UMR 6251 CNRS-Université de Rennes 1, 35042 Rennes Cedex (France); Jouvard, J.-M. [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS-Univ. Bourgogne Franche-Comté, 9 Av. A. Savary, BP 47 870, F-21078 Dijon Cedex (France); Carvou, E. [Institut de Physique de Rennes, UMR 6251 CNRS-Université de Rennes 1, 35042 Rennes Cedex (France); Menneveux, J.; Yu, J. [Institut Lumière Matière, UMR5306 Université Lyon 1-CNRS, Université de Lyon, 69622 Villeurbanne Cedex (France); Ouf, F.-X. [Institut de Radioprotection et de Sureté Nucléaire IRSN/PSN-RES/SCA/LPMA BP 68, 91192 Gif-Sur-Yvette (France); Carles, S. [Institut de Physique de Rennes, UMR 6251 CNRS-Université de Rennes 1, 35042 Rennes Cedex (France); Potin, V.; Pillon, G.; Bourgeois, S. [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS-Univ. Bourgogne Franche-Comté, 9 Av. A. Savary, BP 47 870, F-21078 Dijon Cedex (France); Perez, J. [Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin, F-91192 Gif-sur-Yvette Cedex (France); Marco de Lucas, M.C., E-mail: delucas@u-bourgogne.fr [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS-Univ. Bourgogne Franche-Comté, 9 Av. A. Savary, BP 47 870, F-21078 Dijon Cedex (France); and others

    2016-06-30

    Highlights: • NPs formed in a plasma-plume during laser irradiation of metals (Al, Ti, Ag) were studied. • In situ SAXS and ex situ TEM, XRD and Raman spectra were measured. • NPs size decreased when increasing the O{sub 2} fraction in a controlled O{sub 2}+N{sub 2} atmosphere. • The oxidation of metal NPs in the plasma restricts the increase of the size of the NPs. - Abstract: The influence of a reactive atmosphere on the formation of nanoparticles (NPs) in the plasma plume generated by nanosecond pulsed laser irradiation of metal targets (Ti, Al, Ag) was probed in situ using Small Angle X-ray Scattering (SAXS). Air and different O{sub 2}–N{sub 2} gas mixtures were used as reactive gas within atmospheric pressure. SAXS results showed the formation of NPs in the plasma-plume with a mean radius varying in the 2–5 nm range. A decrease of the NPs size with increasing the O{sub 2} percentage in the O{sub 2}–N{sub 2} gas mixture was also showed. Ex situ observations by transmission electron microscopy and structural characterizations by X-ray diffraction and Raman spectroscopy were also performed for powders collected in experiments done using air as ambient gas. The stability of the different metal oxides is discussed as being a key parameter influencing the formation of NPs in the plasma-plume.

  3. DESIGN OF A DC/RF PHOTOELECTRON GUN

    International Nuclear Information System (INIS)

    YU, D.; NEWSHAM, Y.; SMIRONOV, A.; YU, J.; SMEDLEY, J.; SRINIVASAN RAU, T.; LEWELLEN, J.; ZHOLENTS, A.

    2003-01-01

    An integrated dc/rf photoelectron gun produces a low-emittance beam by first rapidly accelerating electrons at a high gradient during a short (∼1 ns), high-voltage pulse, and then injecting the electrons into an rf cavity for subsequent acceleration. Simulations show that significant improvement of the emittance appears when a high field (∼ 0.5-1 GV/m) is applied to the cathode surface. An adjustable dc gap ((le) 1 mm) which can be integrated with an rf cavity is designed for initial testing at the Injector Test Stand at Argonne National Laboratory using an existing 70-kV pulse generator. Plans for additional experiments of an integrated dc/rf gun with a 250-kV pulse generator are being made

  4. Bidirectional dc-to-dc Power Converter

    Science.gov (United States)

    Griesbach, C. R.

    1986-01-01

    Solid-state, series-resonant converter uses high-voltage thyristors. Converter used either to convert high-voltage, low-current dc power to lowvoltage, high current power or reverse. Taking advantage of newly-available high-voltage thyristors to provide better reliability and efficiency than traditional converters that use vacuum tubes as power switches. New converter essentially maintenance free and provides greatly increased mean time between failures. Attractive in industrial applications whether or not bidirectional capability is required.

  5. A DC Transformer

    Data.gov (United States)

    National Aeronautics and Space Administration — The goal of the project was to demonstrate a true direct current (DC) transformer, a new electro-mechanical component with potentially high power applications; in...

  6. Surface treatment of diamond-like carbon films by reactive Ar/CF{sub 4} high-power pulsed magnetron sputtering plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, Takashi, E-mail: t-kimura@nitech.ac.jp [Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan); Nishimura, Ryotaro [Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan); Azuma, Kingo [Department of Electrical Engineering and Computer Sciences, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280 (Japan); Nakao, Setsuo; Sonoda, Tsutomu; Kusumori, Takeshi; Ozaki, Kimihiro [National Institute of Advanced Industrial Science and Technology (AIST) - Chubu, 2266-98 Anagahora, Moriyama, Nagoya 463-8560 (Japan)

    2015-12-15

    Surface modification of diamond-like carbon films deposited by a high-power pulsed magnetron sputtering (HPPMS) of Ar was carried out by a HPPMS of Ar/CF{sub 4} mixture, changing a CF{sub 4} fraction from 2.5% to 20%. The hardness of the modified films markedly decreased from about 13 to about 3.5 GPa with increasing CF{sub 4} fraction, whereas the water contact angle of the modified films increased from 68° to 109° owing to the increase in the CF{sub x} content on the film surface. C 1s spectra in X-ray photoelectron spectroscopy indicated that a graphitic structure of modified films was formed at CF{sub 4} fractions less than 5%, above which the modified films possessed a polymer-like structure. Influence of treatment time on the properties of the modified films was also investigated in the range of treatment time from 5 to 30 min. The properties of the modified films did not depend on the treatment time in the range of treatment time longer than 10 min, whereas the water contact angle was not sensitive to the treatment time at any treatment time.

  7. REACTIVE POWER DEVICES IN SYSTEMS OF ELECTRIC TRACTION

    Directory of Open Access Journals (Sweden)

    M. O. Kostin

    2010-04-01

    Full Text Available A comparative characteristic of different concepts and expressions for determination of reactive power in the circuits with non-sinusoidal electric values has been given. For the first Ukrainian electric locomotives of DE1 type with the system of DC electric traction, the values of reactive power after Budeany, Fryze, and also the differential, integral and generalized reactive powers have been determined. Some measures on reducing its consumption by the DC electric rolling stock have been suggested.

  8. Controller for computer control of brushless dc motors. [automobile engines

    Science.gov (United States)

    Hieda, L. S. (Inventor)

    1981-01-01

    A motor speed and torque controller for brushless d.c. motors provides an unusually smooth torque control arrangement. The controller provides a means for controlling a current waveform in each winding of a brushless dc motor by synchronization of an excitation pulse train from a programmable oscillator. Sensing of torque for synchronization is provided by a light beam chopper mounted on the motor rotor shaft. Speed and duty cycle are independently controlled by controlling the frequency and pulse width output of the programmable oscillator. A means is also provided so that current transitions from one motor winding to another is effected without abrupt changes in output torque.

  9. Three new DC-to-DC Single-Switch Converters

    Directory of Open Access Journals (Sweden)

    Barry W. Williams

    2017-06-01

    Full Text Available This paper presents a new family of three previously unidentified dc-to-dc converters, buck, boost, and buck-boost voltage-transfer-function topologies, which offer advantageous transformer coupling features and low capacitor dc voltage stressing. The three single-switch, single-diode, converters offer the same features as basic dc-to-dc converters, such as the buck function with continuous output current and the boost function with continuous input current. Converter time-domain simulations and experimental results (including transformer coupling support and extol the dc-to-dc converter concepts and analysis presented.

  10. Zero-Voltage Switching PWM Strategy Based Capacitor Current-Balancing Control for Half-Bridge Three-Level DC/DC Converter

    DEFF Research Database (Denmark)

    Liu, Dong; Deng, Fujin; Zhang, Qi

    2018-01-01

    The current imbalance among the two input capacitors is one of the important issues of the half-bridge threelevel (HBTL) DC/DC converter, which would affect system performance and reliability. In this paper, a zero-voltage switching (ZVS) pulse-wide modulation (PWM) strategy including two operation...

  11. DC Collection Network Simulation for Offshore Wind Farms

    DEFF Research Database (Denmark)

    Vogel, Stephan; Rasmussen, Tonny Wederberg; El-Khatib, Walid Ziad

    2015-01-01

    The possibility to connect offshore wind turbines with a collection network based on Direct Current (DC), instead of Alternating Current (AC), gained attention in the scientific and industrial environment. There are many promising properties of DC components that could be beneficial such as......: smaller dimensions, less weight, fewer conductors, no reactive power considerations, and less overall losses due to the absence of proximity and skin effects. This work describes a study about the simulation of a Medium Voltage DC (MVDC) grid in an offshore wind farm. Suitable converter concepts...

  12. Design and simulation for the pulse high-voltage DC power supply (HVPS) of 1.2 MW/2.45 GHz HT-7U lower hybrid current drive system

    International Nuclear Information System (INIS)

    Huang Yiyun; Kuang Guangli; Xu Weihua; Liu Baohua; Lin Jianan; Wu Junshuan; Zheng Guanghua; Yang Chunshen

    2000-01-01

    The superconducting tokamak HT-7U has been designed by the Institute of Plasma Physics since 1998 and will be set up before 2003. The 1.2 MW/2.45 GHz HT-7U LHCD (Lower hybrid current drive) system which being the most efficient non-induction device can heat the plasma and drive the plasma current has been efficiently in operation now, and a particular design of the 2.8 MW/-35 kV high-voltage DC power supply has been already completed and will apply to the klystron of LHCD on HT-7 and the future HT-7U, and the project of the power supply has been examined and approved professionally by an authorized group of high-level specialist in the Institute of Plasma Physics. The detailed design of the power supply and the simulation results are referred

  13. ASDTIC control and standardized interface circuits applied to buck, parallel and buck-boost dc to dc power converters

    Science.gov (United States)

    Schoenfeld, A. D.; Yu, Y.

    1973-01-01

    Versatile standardized pulse modulation nondissipatively regulated control signal processing circuits were applied to three most commonly used dc to dc power converter configurations: (1) the series switching buck-regulator, (2) the pulse modulated parallel inverter, and (3) the buck-boost converter. The unique control concept and the commonality of control functions for all switching regulators have resulted in improved static and dynamic performance and control circuit standardization. New power-circuit technology was also applied to enhance reliability and to achieve optimum weight and efficiency.

  14. A Secondary Voltage Control Method for an AC/DC Coupled Transmission System Based on Model Predictive Control

    DEFF Research Database (Denmark)

    Xu, Fengda; Guo, Qinglai; Sun, Hongbin

    2015-01-01

    For an AC/DC coupled transmission system, the change of transmission power on the DC lines will significantly influence the AC systems’ voltage. This paper describes a method to coordinated control the reactive power of power plants and shunt capacitors at DC converter stations nearby, in order t...

  15. Ac-dc converter firing error detection

    International Nuclear Information System (INIS)

    Gould, O.L.

    1996-01-01

    Each of the twelve Booster Main Magnet Power Supply modules consist of two three-phase, full-wave rectifier bridges in series to provide a 560 VDC maximum output. The harmonic contents of the twelve-pulse ac-dc converter output are multiples of the 60 Hz ac power input, with a predominant 720 Hz signal greater than 14 dB in magnitude above the closest harmonic components at maximum output. The 720 Hz harmonic is typically greater than 20 dB below the 500 VDC output signal under normal operation. Extracting specific harmonics from the rectifier output signal of a 6, 12, or 24 pulse ac-dc converter allows the detection of SCR firing angle errors or complete misfires. A bandpass filter provides the input signal to a frequency-to-voltage converter. Comparing the output of the frequency-to-voltage converter to a reference voltage level provides an indication of the magnitude of the harmonics in the ac-dc converter output signal

  16. Three-port DC-DC converter with new integrated transformer for DC Distribution Systems

    DEFF Research Database (Denmark)

    Ouyang, Ziwei; Andersen, Michael A. E.

    2014-01-01

    A new integrated transformer for three-port dc-dc converter is proposed to overcome the power coupling effect existed in some known multiple inputs dc-dc converters. Orthogonal primary windings arrangement and in series connection of diagonal secondary Windings enables a fully power decoupling...

  17. 75 FR 23571 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-15, DC...

    Science.gov (United States)

    2010-05-04

    ... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 10-10, DC-10-10F, DC-10-15, DC-10-30, DC-10... amends Sec. 39.13 by adding the following new AD: 2010-09-12 McDonnell Douglas Corporation: Amendment 39... to McDonnell Douglas Corporation Model DC- 10-10, DC-10-10F, DC-10-15, DC-10-30, DC-10-30F (KC-10A...

  18. Design and Testing of Boost Type DC/DC Converter for DC Motor Control Applications

    OpenAIRE

    Samman, Faizal Arya; Akil, Yusri Syam; Noor, Nirwan A.

    2017-01-01

    in The Proceeding of The 2nd International Symposium on Smart Material and Mechatronics 2015 This paper presents the design and testing of a boost type DC/DC converter circuit, which can be used for DC motor control applications. The Boost converter is designed using DC chopper and DC chopper cascade configurations. The experimental setup was made by connecting the boost converter circuit with four types of DC motor, i.e. self-excited DC motor shunt, series, compound and separately exci...

  19. Control of improved full-bridge three-level DC/DC converter for wind turbines in a DC grid

    DEFF Research Database (Denmark)

    Deng, Fujin; Chen, Zhe

    2013-01-01

    transformer in the IFBTL dc/dc converter. A modulation strategy, including two operation modes, is proposed for the IFBTL dc/dc converter. Then, a voltage balancing control strategy is proposed for the IFBTL dc/dc converter. Furthermore, the control of the wind turbine based on the IFBTL dc/dc converter......This paper presents an improved full-bridge three-level (IFBTL) dc/dc converter for a wind turbine in a dc grid by inserting a passive filter into the dc/dc converter to improve the performance of the converter. The passive filter can effectively reduce the voltage stress of the medium frequency...

  20. Studies on the reactive deposition of TiN{sub x} and TiO{sub x} in a DC magnetron plasma; Untersuchungen zur reaktiven Abscheidung von TiN{sub x} und TiO{sub x} in einem DC-Magnetronplasma

    Energy Technology Data Exchange (ETDEWEB)

    Wrehde, Stefan

    2009-10-30

    In the present thesis experiments in a magnetron coating plasma on the (reactive) deposition of Ti, Ti{sub x}, and TiO{sub x} layers were performed. The aim was to meet by correlation of measurements of the ion and energy current on the substrate during the coating procedure with studies of the properties of the deposed layers statements about the connections of deposition conditions and layer properties. The layers deposed in the argon plasma without reactive gas contained beside titanium as main component also small concentrations of oxygen in the range of 8..15%, no completely pure respectively metallic titanium layers could be deposed. In the layers deposed in the argon-nitrogen plasma the increasing nitrogen admixture to the plasma leads mto an increasing nitridation of the layers. The measurements of the crystal structure show higher macroscopical stresses in the layers deposed in the unbalanced mode. From the combination of the higher thicknesses and densities of the layers deposed in the unbalanced mode in this operation mode of the magnetron higher deposition rates result. In the argon-oxygen plasma at increasing oxygen part it comes to a distinct increasement of the oxygen concentration at simultaneous decreasement of the relative titanium concentration in the deposed layers. The deposition in the unbalanced mode leads against the that in the balanced mode to a slightly lower oxygen concentration in the layers. The measurements of the crystal structure show also a lower oxygen insertion and tendentially lower macroscopical stresses in the layers deposed in the unbalanced mode. The measured densities of the layers deposed in the unbalanced mode are distinctly lower than to be expected, and above all smaller than those of the layers deposed in the balanced mode.

  1. Overview of Multi-DC-Bus Solutions for DC Microgrids

    DEFF Research Database (Denmark)

    Ricchiuto, D.; Mastromauro, R.A.; Liserre, Marco

    2013-01-01

    DC Microgrids have recently received a lot of attention in the last years due to high penetration of renewable energy sources as well as distributed energy storage systems. In the future DC microgrids could be preferable respect to AC microgrids in terms of redundancy since multi-DC-Bus solutions...... could provide a continuative power supply to the loads. An overview of Multi-DC-Bus solutions is presented in this paper. The performances are compared on the basis of possible DC microgrid configurations, redundancy, different DC voltage levels....

  2. Series-Connected High Frequency Converters in a DC Microgrid System for DC Light Rail Transit

    Directory of Open Access Journals (Sweden)

    Bor-Ren Lin

    2018-01-01

    Full Text Available This paper studies and presents a series-connected high frequency DC/DC converter connected to a DC microgrid system to provide auxiliary power for lighting, control and communication in a DC light rail vehicle. Three converters with low voltage and current stresses of power devices are series-connected with single transformers to convert a high voltage input to a low voltage output for a DC light rail vehicle. Thus, Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs with a low voltage rating and a turn-on resistance are adopted in the proposed circuit topology in order to decrease power losses on power switches and copper losses on transformer windings. A duty cycle control with an asymmetric pulse-width modulation is adopted to control the output voltage at the desired voltage level. It is also adopted to reduce switching losses on MOSFETs due to the resonant behavior from a leakage inductor of an isolated transformer and output capacitor of MOSFETs at the turn-on instant. The feasibility and effectiveness of the proposed circuit have been verified by a laboratory prototype with a 760 V input and a 24 V/60 A output.

  3. Motor control for a brushless DC motor

    Science.gov (United States)

    Peterson, William J. (Inventor); Faulkner, Dennis T. (Inventor)

    1985-01-01

    This invention relates to a motor control system for a brushless DC motor having an inverter responsively coupled to the motor control system and in power transmitting relationship to the motor. The motor control system includes a motor rotor speed detecting unit that provides a pulsed waveform signal proportional to rotor speed. This pulsed waveform signal is delivered to the inverter to thereby cause an inverter fundamental current waveform output to the motor to be switched at a rate proportional to said rotor speed. In addition, the fundamental current waveform is also pulse width modulated at a rate proportional to the rotor speed. A fundamental current waveform phase advance circuit is controllingly coupled to the inverter. The phase advance circuit is coupled to receive the pulsed waveform signal from the motor rotor speed detecting unit and phase advance the pulsed waveform signal as a predetermined function of motor speed to thereby cause the fundamental current waveform to be advanced and thereby compensate for fundamental current waveform lag due to motor winding reactance which allows the motor to operate at higher speeds than the motor is rated while providing optimal torque and therefore increased efficiency.

  4. 3 MeV DC accelerator, EBC Kharghar

    International Nuclear Information System (INIS)

    Bakhtsingh, R.I.; Acharya, S.

    2017-01-01

    The Accelerator and Pulse Power Division (APPD) has designed and developed a 3 MeV, 10 mA DC electron beam accelerator at Electron Beam Centre, Kharghar, Navi Mumbai. This machine has been utilized for reduction of SO_x and NO_x in simulated flue gases and treatment of waste water to reduce COD and BOD

  5. Harmonic analysis of DC capacitor current in sinusoidal and space ...

    Indian Academy of Sciences (India)

    DC capacitor current in a three-level neutral-point clamped (NPC) inverter, modu- lated with ... For control of the switches in two-level and three-level inverters, numerous pulse-width mod- ..... coincide with each other, and lie on the horizontal axis in figure 5b. The loci of the ... A MATLAB code is written for the purpose. 5.

  6. Multi Bus DC-DC Converter in Electric Hybrid Vehicles

    Science.gov (United States)

    Krithika, V.; Subramaniam, C.; Sridharan, R.; Geetha, A.

    2018-04-01

    This paper is cotncerned with the design, simulation and fabrication of the prototype of a Multi bus DC- DC converter operating from 42V DC and delivering 14V DC and 260V DC. As a result, three DC buses are interconnected through a single power electronic circuitry. Such a requirement is energized in the development of a hybrid electric automobile which uses the technology of fuel cell. This is implemented by using a Bidirectional DC-DC converter configuration which is ideally suitable for multiple outputs with mutual electrical isolation. For the sake of reduced size and cost of step-up transformer, selection of a high frequency switching cycle at 10 KHz was done.

  7. Coiled transmission line pulse generators

    Science.gov (United States)

    McDonald, Kenneth Fox

    2010-11-09

    Methods and apparatus are provided for fabricating and constructing solid dielectric "Coiled Transmission Line" pulse generators in radial or axial coiled geometries. The pour and cure fabrication process enables a wide variety of geometries and form factors. The volume between the conductors is filled with liquid blends of monomers, polymers, oligomers, and/or cross-linkers and dielectric powders; and then cured to form high field strength and high dielectric constant solid dielectric transmission lines that intrinsically produce ideal rectangular high voltage pulses when charged and switched into matched impedance loads. Voltage levels may be increased by Marx and/or Blumlein principles incorporating spark gap or, preferentially, solid state switches (such as optically triggered thyristors) which produce reliable, high repetition rate operation. Moreover, these Marxed pulse generators can be DC charged and do not require additional pulse forming circuitry, pulse forming lines, transformers, or an a high voltage spark gap output switch. The apparatus accommodates a wide range of voltages, impedances, pulse durations, pulse repetition rates, and duty cycles. The resulting mobile or flight platform friendly cylindrical geometric configuration is much more compact, light-weight, and robust than conventional linear geometries, or pulse generators constructed from conventional components. Installing additional circuitry may accommodate optional pulse shape improvements. The Coiled Transmission Lines can also be connected in parallel to decrease the impedance, or in series to increase the pulse length.

  8. Pulse Generator

    Science.gov (United States)

    Greer, Lawrence (Inventor)

    2017-01-01

    An apparatus and a computer-implemented method for generating pulses synchronized to a rising edge of a tachometer signal from rotating machinery are disclosed. For example, in one embodiment, a pulse state machine may be configured to generate a plurality of pulses, and a period state machine may be configured to determine a period for each of the plurality of pulses.

  9. Early Oscillation Detection for DC/DC Converter Fault Diagnosis

    Science.gov (United States)

    Wang, Bright L.

    2011-01-01

    The electrical power system of a spacecraft plays a very critical role for space mission success. Such a modern power system may contain numerous hybrid DC/DC converters both inside the power system electronics (PSE) units and onboard most of the flight electronics modules. One of the faulty conditions for DC/DC converter that poses serious threats to mission safety is the random occurrence of oscillation related to inherent instability characteristics of the DC/DC converters and design deficiency of the power systems. To ensure the highest reliability of the power system, oscillations in any form shall be promptly detected during part level testing, system integration tests, flight health monitoring, and on-board fault diagnosis. The popular gain/phase margin analysis method is capable of predicting stability levels of DC/DC converters, but it is limited only to verification of designs and to part-level testing on some of the models. This method has to inject noise signals into the control loop circuitry as required, thus, interrupts the DC/DC converter's normal operation and increases risks of degrading and damaging the flight unit. A novel technique to detect oscillations at early stage for flight hybrid DC/DC converters was developed.

  10. Conversion of continuous-direct-current TIG welder to pulse-arc operation

    Science.gov (United States)

    Lien, D. R.

    1969-01-01

    Electronics package converts a continuous-dc tungsten-inert gas welder for pulse-arc operation. Package allows presetting of the pulse rate, duty cycle, and current value, and enables welding of various alloys and thicknesses of materials.

  11. A ZVS PWM control strategy with balanced capacitor current for half-bridge three-level DC/DC converter

    DEFF Research Database (Denmark)

    Liu, Dong; Deng, Fujin; Chen, Zhe

    2017-01-01

    The capacitor current would be imbalanced under the conventional control strategy in the half-bridge three-level (HBTL) DC/DC converter due to the effect of the output inductance of the power supply and the input line inductance, which would affect the converter's reliability. This paper proposes...... a pulse-wide modulation (PWM) strategy composed of two operation modes for the HBTL DC/DC converter, which can realize the zero-voltage switching (ZVS) for the efficiency improvement. In addition, a capacitor current balancing control is proposed by alternating the two operation modes of the proposed ZVS...... PWM strategy, which can eliminate the current imbalance among the two input capacitors. Therefore, the proposed control strategy can improve the converter's performance and reliability in: 1) reducing the switching losses and noises of the power switches; 2) balancing the thermal stresses...

  12. Thyristors for dc transmission

    Energy Technology Data Exchange (ETDEWEB)

    1966-05-06

    As a first stage towards determining the feasibility of applying thyristors to hvdc converter terminals, the Westinghouse Electric Corporation has built a converter laboratory capable of testing thyristors under conditions similar to those which would have to be met in a 200 kV dc system. The equipment has been designed to test a 5 kV 600 A group of thyrisotrs, elevated 200 kV above earth. This rating has been chosen so that there would be a sufficient number of thyristors in series to enable the gating and voltage division characteristics to be investigated and at the same time the group could be operated at a potential equivalent to a complete 200 kV dc bridge.

  13. TOPOLOGICAL REVIEW AND ANALYSIS OF DC-DC BOOST CONVERTERS

    Directory of Open Access Journals (Sweden)

    V. INDRA GANDHI

    2017-06-01

    Full Text Available DC voltage boost up is essential in numerous applications; especially considering Photovoltaic (PV based renewable power generation system. The conventional DC-DC boost converter is the most admired configuration for this scheme, even if the converter efficiency is restricted at duty cycle near to maximum value. In order to find solution to the problem and improve its conversion capability, many converter configurations have been implemented so far. With this circumstance, this research work proposes to give overview of a few most imperative research works related to DC-DC boost converters. Some configurations are covered and classified basically based on the application. The major benefits and disadvantages related to the available techniques are also briefly conveyed. At last, a proper evaluation is recognized among the important types of DC-DC boost converters in terms of efficiency, number of components, and stability.

  14. Preliminary design of the ITER AC/DC converters supplied by the Korean Domestic Agency

    International Nuclear Information System (INIS)

    Oh, J.S.; Choi, J.; Suh, J.H.; Liu, H.; Hwang, K.; Chung, I.; Lee, S.; Kang, J.; Park, H.; Jung, W.; Jo, S.; Gweon, H.; Lee, Y.; Lee, W.; Kim, J.B.; Han, S.H.; Hong, G.D.; Lee, J.S.; Lee, B.W.; Yeo, C.H.

    2013-01-01

    Highlights: ► A self-supporting aluminium structure and symmetrical thyristor assembly are devised to assure a strong and reliable ITER converter. ► Converters are designed to be installable in a compact space with three times higher power density than normal industrial installations. ► Heating of the building structure due to high magnetic field by converters are identified and certain solutions are addressed in the building design. ► A cooperative fast control scheme is adopted to compensate fast reactive power change of up to the level of 900 Mvar. -- Abstract: The preliminary design for ITER AC/DC converters under the responsibility of the Korean Domestic Agency is performed on the basis of the engineering experience of previous R and D for a full-scale 6-pulse CS (Central Solenoid) converter unit. This paper describes key features of the preliminary design for the respective sub-systems; integrated self-supporting aluminium structure and symmetrical thyristor assembly for strong and reliable converters, optimised impedance of the converter transformer to limit short circuit current, coaxial-type AC bus bars to shield high magnetic field around wall penetrations, compact components to fit into given building space. The insulation and the minimisation of electrical loops of concrete rebar below the converter installations are essential to prevent floor heating. Required output voltage or current of converters is provided by a conventional controller. A master controller is designed to collect predicted reactive powers from each converter and deliver processed data to the reactive power compensation (RPC) system to improve the regulation speed of the RPC controller with fast feed-forward compensation under fast reactive power transients

  15. Preliminary design of the ITER AC/DC converters supplied by the Korean Domestic Agency

    Energy Technology Data Exchange (ETDEWEB)

    Oh, J.S., E-mail: jsoh@nfri.re.kr [ITER Korea, National Fusion Research Institute, Daejeon 305-806 (Korea, Republic of); Choi, J.; Suh, J.H. [ITER Korea, National Fusion Research Institute, Daejeon 305-806 (Korea, Republic of); Liu, H.; Hwang, K.; Chung, I.; Lee, S.; Kang, J.; Park, H.; Jung, W.; Jo, S.; Gweon, H.; Lee, Y.; Lee, W. [Dawonsys Corp., Siheung 429-450 (Korea, Republic of); Kim, J.B.; Han, S.H.; Hong, G.D.; Lee, J.S.; Lee, B.W.; Yeo, C.H. [Hyosung Corp., 450, Gongdeok-Dong, Seoul 121-720 (Korea, Republic of); and others

    2013-10-15

    Highlights: ► A self-supporting aluminium structure and symmetrical thyristor assembly are devised to assure a strong and reliable ITER converter. ► Converters are designed to be installable in a compact space with three times higher power density than normal industrial installations. ► Heating of the building structure due to high magnetic field by converters are identified and certain solutions are addressed in the building design. ► A cooperative fast control scheme is adopted to compensate fast reactive power change of up to the level of 900 Mvar. -- Abstract: The preliminary design for ITER AC/DC converters under the responsibility of the Korean Domestic Agency is performed on the basis of the engineering experience of previous R and D for a full-scale 6-pulse CS (Central Solenoid) converter unit. This paper describes key features of the preliminary design for the respective sub-systems; integrated self-supporting aluminium structure and symmetrical thyristor assembly for strong and reliable converters, optimised impedance of the converter transformer to limit short circuit current, coaxial-type AC bus bars to shield high magnetic field around wall penetrations, compact components to fit into given building space. The insulation and the minimisation of electrical loops of concrete rebar below the converter installations are essential to prevent floor heating. Required output voltage or current of converters is provided by a conventional controller. A master controller is designed to collect predicted reactive powers from each converter and deliver processed data to the reactive power compensation (RPC) system to improve the regulation speed of the RPC controller with fast feed-forward compensation under fast reactive power transients.

  16. DC-DC Type High-Frequency Link DC for Improved Power Quality of Cascaded Multilevel Inverter

    Science.gov (United States)

    Sadikin, Muhammad; Senjyu, Tomonobu; Yona, Atsushi

    2013-06-01

    Multilevel inverters are emerging as a new breed of power converter options for power system applications. Recent advances in power switching devices enabled the suitability of multilevel inverters for high voltage and high power applications because they are connecting several devices in series without the need of component matching. Usually, a transformerless battery energy storage system, based on a cascaded multilevel inverter, is used as a measure for voltage and frequency deviations. System can be reduced in size, weight, and cost of energy storage system. High-frequency link circuit topology is advantageous in realizing compact and light-weight power converters for uninterruptible power supply systems, new energy systems using photovoltaic-cells, fuel-cells and so on. This paper presents a DC-DC type high-frequency link DC (HFLDC) cascaded multilevel inverter. Each converter cell is implemented a control strategy for two H-bridge inverters that are controlled with the same multicarrier pulse width modulation (PWM) technique. The proposed cascaded multilevel inverter generates lower voltage total harmonic distortion (THD) in comparison with conventional cascaded multilevel inverter. Digital simulations are carried out using PSCAD/EMTDC to validate the performance of the proposed cascaded multilevel inverter.

  17. Method for integrating a train of fast, nanosecond wide pulses

    International Nuclear Information System (INIS)

    Rose, C.R.

    1987-01-01

    This paper describes a method used to integrate a train of fast, nanosecond wide pulses. The pulses come from current transformers in a RF LINAC beamline. Because they are ac signals and have no dc component, true mathematical integration would yield zero over the pulse train period or an equally erroneous value because of a dc baseline shift. The circuit used to integrate the pulse train first stretches the pulses to 35 ns FWHM. The signals are then fed into a high-speed, precision rectifier which restores a true dc baseline for the following stage - a fast, gated integrator. The rectifier is linear over 55dB in excess of 25 MHz, and the gated integrator is linear over a 60 dB range with input pulse widths as short as 16 ns. The assembled system is linear over 30 dB with a 6 MHz input signal

  18. An Integrated Multifunctional Bidirectional AC/DC and DC/DC Converter for Electric Vehicles Applications

    OpenAIRE

    Liwen Pan; Chengning Zhang

    2016-01-01

    This paper presents an on-board vehicular battery charger that integrates bidirectional AC/DC converter and DC/DC converter to achieve high power density for application in electric vehicles (EVs). The integrated charger is able to transfer electrical energy between the battery pack and the electric traction system and to function as an AC/DC battery charger. The integrated charger topology is presented and the design of passive components is discussed. The control schemes are developed for m...

  19. DC Stark addressing for quantum memory in Tm:YAG

    Science.gov (United States)

    Gerasimov, Konstantin; Minnegaliev, Mansur; Urmancheev, Ravil; Moiseev, Sergey

    2017-10-01

    We observed a linear DC Stark effect for 3H6 - 3H4 optical transition of Tm3+ ions in Y3Al5O12. We observed that application of electric field pulse suppresses the two-pulse photon echo signal. If we then apply a second electric pulse of opposite polarity the echo signal is restored again, which indicates the linear nature of the observed effect. The effect is present despite the D2 symmetry of the Tm3+ sites that prohibits a linear Stark effect. Experimental data analysis shows that the observed electric field influence can be attributed to defects that break the local crystal field symmetry near Tm3+ ions. Using this effect we demonstrate selective retrieval of light pulses in two-pulse photon echo.

  20. Pulse width modulation inverter with battery charger

    Science.gov (United States)

    Slicker, James M.

    1985-01-01

    An inverter is connected between a source of DC power and a three-phase AC induction motor, and a microprocessor-based circuit controls the inverter using pulse width modulation techniques. In the disclosed method of pulse width modulation, both edges of each pulse of a carrier pulse train are equally modulated by a time proportional to sin .theta., where .theta. is the angular displacement of the pulse center at the motor stator frequency from a fixed reference point on the carrier waveform. The carrier waveform frequency is a multiple of the motor stator frequency. The modulated pulse train is then applied to each of the motor phase inputs with respective phase shifts of 120.degree. at the stator frequency. Switching control commands for electronic switches in the inverter are stored in a random access memory (RAM) and the locations of the RAM are successively read out in a cyclic manner, each bit of a given RAM location controlling a respective phase input of the motor. The DC power source preferably comprises rechargeable batteries and all but one of the electronic switches in the inverter can be disabled, the remaining electronic switch being part of a "flyback" DC-DC converter circuit for recharging the battery.

  1. The effect of applied electric field on pulsed radio frequency and pulsed direct current plasma jet array

    International Nuclear Information System (INIS)

    Hu, J. T.; Liu, X. Y.; Liu, J. H.; Xiong, Z. L.; Liu, D. W.; Lu, X. P.; Iza, F.; Kong, M. G.

    2012-01-01

    Here we compare the plasma plume propagation characteristics of a 3-channel pulsed RF plasma jet array and those of the same device operated by a pulsed dc source. For the pulsed-RF jet array, numerous long life time ions and metastables accumulated in the plasma channel make the plasma plume respond quickly to applied electric field. Its structure similar as “plasma bullet” is an anode glow indeed. For the pulsed dc plasma jet array, the strong electric field in the vicinity of the tube is the reason for the growing plasma bullet in the launching period. The repulsive forces between the growing plasma bullets result in the divergence of the pulsed dc plasma jet array. Finally, the comparison of 309 nm and 777 nm emissions between these two jet arrays suggests the high chemical activity of pulsed RF plasma jet array.

  2. Commutator dc machines used as mechanical capacitors in a series resonant ohmic-heating circuit simulation

    International Nuclear Information System (INIS)

    Thullen, P.; Weldon, D.M.

    1979-01-01

    Rotating electrical machines, and in particular commutator dc machines can serve as a high-power energy-source for testing large, pulsed magnets. This paper describes a pulsed power supply based on traction motors which will be used to test the LASL prototype 20-MJ superconducting tokamak induction coil

  3. Improvements of Nickel Deposit Characteristics by Pulse Plating

    DEFF Research Database (Denmark)

    Tang, Peter Torben; Leisner, Peter; Møller, Per

    1993-01-01

    Investigation of the properties of electroplated nickel, using both pulse plating and conventional di-rect current (DC), has lead to several interesting improvements of deposit characteristics. Investigated properties include; internal stress, tensile strength, yield stress, elongation, hardness...

  4. Automation of Aditya tokamak plasma position control DC power supply

    Energy Technology Data Exchange (ETDEWEB)

    Arambhadiya, Bharat, E-mail: bharat@ipr.res.in; Raj, Harshita; Tanna, R.L.; Edappala, Praveenlal; Rajpal, Rachana; Ghosh, Joydeep; Chattopadhyay, P.K.; Kalal, M.B.

    2016-11-15

    Highlights: • Plasma position control is very essential for obtaining repeatable high temperature, high-density discharges of longer durations in tokomak. • The present capacitor bank has limitations of maximum current capacity and position control beyond 200 ms. • The installation of a separate set of coils and a DC power supply can control the plasma position beyond 200 ms. • A high power thyristor (T588N1200) triggers for DC current pulse of 300 A fires precisely at required positions to modify plasma position. • The commissioning is done for the automated in-house, quick and reliable solution. - Abstract: Plasma position control is essential for obtaining repeatable high temperature, high-density discharges of longer duration in tokamaks. Recently, a set of external coils is installed in the vertical field mode configuration to control the radial plasma position in ADITYA tokamak. The existing capacitor bank cannot provide the required current pulse beyond 200 ms for position control. This motivated to have a DC power supply of 500 A to provide current pulse beyond 200 ms for the position control. The automatization of the DC power supply mandated interfaces with the plasma control system, Aditya Pulse Power supply, and Data acquisition system for coordinated discharge operation. A high current thyristor circuit and a timer circuit have been developed for controlling the power supply automatically for charging vertical field coils of Aditya tokamak. Key protection interlocks implemented in the development ensure machine and occupational safety. Fiber-optic trans-receiver isolates the power supply with other subsystems, while analog channel is optically isolated. Commissioning and testing established proper synchronization of the power supply with tokamak operation. The paper discusses the automation of the DC power supply with main circuit components, timing control, and testing results.

  5. On and off controlled resonant dc-dc power converter

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention relates to a resonant DC-DC power converter comprising an input side circuit comprising a positive and a negative input terminal for receipt of an input voltage or current and an output side circuit comprising positive and negative output terminals for supply of a converter...... output voltage and connection to a converter load. The resonant DC-DC power converter further comprises a rectification circuit connected between an output of a resonant network and the output side circuit. The resonant network is configured for alternatingly being charged from the input voltage...... or current and discharged through the rectification circuit by a first controllable switch arrangement in accordance with a first switch control signal. A second controllable switch arrangement of the resonant DC-DC power converter is configured to select a first impedance characteristic of the resonant...

  6. DC Cable for Railway

    Science.gov (United States)

    Tomita, Masaru

    The development of a superconducting cable for railways has commenced, assuming that a DC transmission cable will be used for electric trains. The cable has been fabricated based on the results of current testing of a superconducting wire, and various evaluation tests have been performed to determine the characteristics of the cable. A superconducting transmission cable having zero electrical resistance and suitable for railway use is expected to enhance regeneration efficiency, reduce power losses, achieve load leveling and integration of sub-stations, and reduce rail potential.

  7. DC and AC biasing of a transition edge sensor microcalorimeter

    International Nuclear Information System (INIS)

    Cunningham, M.F.; Ullom, J.N.; Miyazaki, T.; Drury, O.; Loshak, A.; Berg, M.L. van den; Labov, S.E.

    2002-01-01

    We are developing AC-biased transition edge sensor (TES) microcalorimeters for use in large arrays with frequency-domain multiplexing. Using DC bias, we have achieved a resolution of 17 eV FWHM at 2.6 keV with a decay time of 90 μs and an effective detector diameter of 300 μm. We have successfully measured thermal pulses with a TES microcalorimeter operated with an AC bias. We present here preliminary results from a single pixel detector operated under DC and AC bias conditions

  8. Auxiliary resonant DC tank converter

    Science.gov (United States)

    Peng, Fang Z.

    2000-01-01

    An auxiliary resonant dc tank (ARDCT) converter is provided for achieving soft-switching in a power converter. An ARDCT circuit is coupled directly across a dc bus to the inverter to generate a resonant dc bus voltage, including upper and lower resonant capacitors connected in series as a resonant leg, first and second dc tank capacitors connected in series as a tank leg, and an auxiliary resonant circuit comprising a series combination of a resonant inductor and a pair of auxiliary switching devices. The ARDCT circuit further includes first clamping means for holding the resonant dc bus voltage to the dc tank voltage of the tank leg, and second clamping means for clamping the resonant dc bus voltage to zero during a resonant period. The ARDCT circuit resonantly brings the dc bus voltage to zero in order to provide a zero-voltage switching opportunity for the inverter, then quickly rebounds the dc bus voltage back to the dc tank voltage after the inverter changes state. The auxiliary switching devices are turned on and off under zero-current conditions. The ARDCT circuit only absorbs ripples of the inverter dc bus current, thus having less current stress. In addition, since the ARDCT circuit is coupled in parallel with the dc power supply and the inverter for merely assisting soft-switching of the inverter without participating in real dc power transmission and power conversion, malfunction and failure of the tank circuit will not affect the functional operation of the inverter; thus a highly reliable converter system is expected.

  9. PENGGUNAAN FUZZY LOGIC UNTUK KONTROL PARALLEL CONVERTER DC-DC

    Directory of Open Access Journals (Sweden)

    Bambang Prio Hartono

    2012-09-01

    Full Text Available Abstract: Using system fuzzy logic as control  technology have been used on low load dc-dc converter with combined parallel compiled  dc-dc converter can  obtain big load.   With existence of differrence of component parameter and each parallel compiled converter can obtained different current  and voltage output.  Function of controller  for to do adjustment, so that current which is applied  to  load by each converter  can be obtained  difference error as small as possible or same. The object of research is developing design of large signal dc-dc converter which is  combined with using  FLC so that  obtain  better performance.  To get better performance have been made plant model and simulation with CDE method.  The more systematic  system and design is needed to overcome bigger load  on dc-dc converter, so that parallel  compiled current master slave control system on dc-dc converter with using fuzzy logic  controller is used. Result of  research showed that error or difference of  current  which is applied to load can handled by fuzzy logic  controller.  Technic of current and voltage controller co to do adjustment current and voltage distribution  equally to load.  Distribution of iL1,iL2 and  output voltage Vo on dc-dc  converter with load 2,25 until  7,875 and voltage  100  until 120 volt,  load current beetwen  12 until 48, % relatif  error  Vo  0,4% until  0,9%.

  10. Step-Up DC-DC Power Converter

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention relates to a step-up DC-DC power converter which comprises a primary side circuit and a secondary side circuit coupled through a galvanic isolation barrier. The primary side circuit comprises a positive and a negative input terminal for receipt of an input voltage and an input...... being charged from the input voltage and discharged to the output capacitor through the galvanic isolation barrier in accordance with a switch control signal to produce the converter output voltage. The step-up DC-DC power converter comprises an electrical short-circuit connection across the galvanic...

  11. Utility Interfaced Pulse-Width Modulation of Solar Fed Voltage ...

    African Journals Online (AJOL)

    Utility Interfaced Pulse-Width Modulation of Solar Fed Voltage Source Inverter Using Fixed-Band Hysteresis Current Controller Method. ... with the conversion of solar energy into electrical energy; boosting the dc power; inversion of the dc to ac and then synchronization of the inverter output with the utility, and consequently, ...

  12. Amino-terminal pro-B-type natriuretic peptide and high-sensitivity C-reactive protein but not cystatin C predict cardiovascular events in male patients with peripheral artery disease independently of ambulatory pulse pressure.

    Science.gov (United States)

    Skoglund, Per H; Arpegård, Johannes; Ostergren, Jan; Svensson, Per

    2014-03-01

    Patients with peripheral arterial disease (PAD) are at high risk for cardiovascular (CV) events. We have previously shown that ambulatory pulse pressure (APP) predicts CV events in PAD patients. The biomarkers amino-terminal pro-B-type natriuretic peptide (NT-proBNP), high-sensitivity C-reactive protein (hs-CRP), and cystatin C are related to a worse outcome in patients with CV disease, but their predictive values have not been studied in relation to APP. Blood samples and 24-hour measurements of ambulatory blood pressure were examined in 98 men referred for PAD evaluation during 1998-2001. Patients were followed for a median of 71 months. The outcome variable was CV events defined as either CV mortality or any hospitalization for myocardial infarction, stroke, or coronary revascularization. The predictive values of log(NT-proBNP), log(hs-CRP), and log(cystatin C) alone and together with APP were assessed by multivariable Cox regression. Area under the curve (AUC) and net reclassification improvement (NRI) were calculated compared with a model containing other significant risk factors. During follow-up, 36 patients had at least 1 CV event. APP, log(NT-proBNP), and log(hs-CRP) all predicted CV events in univariable analysis, whereas log(cystatin C) did not. In multivariable analysis log(NT-proBNP) (hazard ratio (HR) = 1.62; 95% confidence interval (CI) = 1.05-2.51) and log(hs-CRP) (HR = 1.63; 95% CI = 1.19-2.24) predicted events independently of 24-hour PP. The combination of log(NT-proBNP), log(hs-CRP), and average day PP improved risk discrimination (AUC = 0.833 vs. 0.736; P < 0.05) and NRI (37%; P < 0.01) when added to other significant risk factors. NT-proBNP and hs-CRP predict CV events independently of APP and the combination of hs-CRP, NT-proBNP, and day PP improves risk discrimination in PAD patients.

  13. PSCAD modeling of a two-level space vector pulse width modulation algorithm for power electronics education

    Directory of Open Access Journals (Sweden)

    Ahmet Mete Vural

    2016-09-01

    Full Text Available This paper presents the design details of a two-level space vector pulse width modulation algorithm in PSCAD that is able to generate pulses for three-phase two-level DC/AC converters with two different switching patterns. The presented FORTRAN code is generic and can be easily modified to meet many other kinds of space vector modulation strategies. The code is also editable for hardware programming. The new component is tested and verified by comparing its output as six gating signals with those of a similar component in MATLAB library. Moreover the component is used to generate digital signals for closed-loop control of STATCOM for reactive power compensation in PSCAD. This add-on can be an effective tool to give students better understanding of the space vector modulation algorithm for different control tasks in power electronics area, and can motivate them for learning.

  14. DC Distribution Systems and Microgrids

    DEFF Research Database (Denmark)

    Dragicevic, Tomislav; Anvari-Moghaddam, Amjad; Quintero, Juan Carlos Vasquez

    2017-01-01

    summarized. Due to its attractive characteristics in terms of compliance with modern generation, storage and electronic load technologies, high reliability and current carrying capacity, as well as simple control, DC systems are already an indispensable part of power systems. Moreover, the existing......A qualitative overview of different hardware topologies and control systems for DC MGs has been presented in this chapter. Some challenges and design considerations of DC protections systems have also been discussed. Finally, applications of DC MGs in emerging smart grid applications have been...... challenges such as protection issues will be effectively resolved in the near future due to fast progress of semiconductor technology which is a key enabler cheap and reliable future DC solid-state protection systems. Therefore, it is the view of the author that more and more DC systems will appear...

  15. Pulse Circuits of Radar Stations

    Science.gov (United States)

    1982-08-06

    be less than in a symmetrical flip-flop since voltage webs additionally is reduced, given presence of cathode coupling (triode L2 cathode potential...and t, f(t). 636 7o%:i. iI where C’ - d-c component equal, in accordance with (1.5) -- L. ( * -. wiX " -- angular pulse repetition frequency tPRF]; T. K

  16. Reactive Arthritis

    Directory of Open Access Journals (Sweden)

    Eren Erken

    2013-06-01

    Full Text Available Reactive arthritis is an acute, sterile, non-suppurative and inflammatory arthropaty which has occured as a result of an infectious processes, mostly after gastrointestinal and genitourinary tract infections. Reiter syndrome is a frequent type of reactive arthritis. Both reactive arthritis and Reiter syndrome belong to the group of seronegative spondyloarthropathies, associated with HLA-B27 positivity and characterized by ongoing inflammation after an infectious episode. The classical triad of Reiter syndrome is defined as arthritis, conjuctivitis and urethritis and is seen only in one third of patients with Reiter syndrome. Recently, seronegative asymmetric arthritis and typical extraarticular involvement are thought to be adequate for the diagnosis. However, there is no established criteria for the diagnosis of reactive arthritis and the number of randomized and controlled studies about the therapy is not enough. [Archives Medical Review Journal 2013; 22(3.000: 283-299

  17. Very High Frequency Half Bridge DC/DC Converter

    DEFF Research Database (Denmark)

    Madsen, Mickey Pierre; Knott, Arnold; Andersen, Michael A. E.

    2014-01-01

    This paper presents the first, off chip, class DE (resonant half bridge) converter working in the Very High Frequency (VHF) range. The benefits of using half bridge circuits both in the inverter and rectifier part of a VHF resonant dc/dc converter are analyzed and design equations for all...

  18. SCM Handbooks for dc-to-dc Converters

    Science.gov (United States)

    Lee, F.; Mohmoud, M.; Yu, Y.

    1984-01-01

    Two documents aid in design of control modules for dc-to-dc converters. Features of SCM include: Adaptive stability, power component stress limiting, implementation of various control laws, unified design approach. Analysis and quidelines contained in handbooks enable engineer to design SCM circuit and confidently predict resulting overall performance.

  19. Sheppard-Taylor Isolated High Boost DC-DC Converter

    DEFF Research Database (Denmark)

    Chub, Andrii; Siwakoti, Yam Prasad; Vinnikov, Dmitri

    2017-01-01

    This paper presents a new galvanically isolated step-up dc-dc converter intended for low-power but high step-up applications. The proposed converter is capable of regulating output voltage within a wide range of the input voltage or load variations. In contrast to competitors, the converter can...

  20. A Current-Fed Isolated Bidirectional DC-DC Converter

    DEFF Research Database (Denmark)

    Sun, Xiaofeng; Wu, Xiaoying; Shen, Yanfeng

    2017-01-01

    This paper proposes a current-fed isolated bidirectional DC-DC converter (CF-IBDC) which has the advantages of wide input voltage range, low input current ripple, low conduction losses, and soft switching over the full operating range. Compared with conventional CF-IBDCs, the voltage spikes...

  1. Power flow analysis for DC voltage droop controlled DC microgrids

    DEFF Research Database (Denmark)

    Li, Chendan; Chaudhary, Sanjay; Dragicevic, Tomislav

    2014-01-01

    This paper proposes a new algorithm for power flow analysis in droop controlled DC microgrids. By considering the droop control in the power flow analysis for the DC microgrid, when compared with traditional methods, more accurate analysis results can be obtained. The algorithm verification is ca...

  2. A DC Transformer

    Science.gov (United States)

    Youngquist, Robert C.; Ihlefeld, Curtis M.; Starr, Stanley O.

    2013-01-01

    A component level dc transformer is described in which no alternating currents or voltages are present. It operates by combining features of a homopolar motor and a homopolar generator, both de devices, such that the output voltage of a de power supply can be stepped up (or down) with a corresponding step down (or up) in current. The basic theory for this device is developed, performance predictions are made, and the results from a small prototype are presented. Based on demonstrated technology in the literature, this de transformer should be scalable to low megawatt levels, but it is more suited to high current than high voltage applications. Significant development would be required before it could achieve the kilovolt levels needed for de power transmission.

  3. Design of a -1 MV dc UHV power supply for ITER NBI

    Science.gov (United States)

    Watanabe, K.; Yamamoto, M.; Takemoto, J.; Yamashita, Y.; Dairaku, M.; Kashiwagi, M.; Taniguchi, M.; Tobari, H.; Umeda, N.; Sakamoto, K.; Inoue, T.

    2009-05-01

    Procurement of a dc -1 MV power supply system for the ITER neutral beam injector (NBI) is shared by Japan and the EU. The Japan Atomic Energy Agency as the Japan Domestic Agency (JADA) for ITER contributes to the procurement of dc -1 MV ultra-high voltage (UHV) components such as a dc -1 MV generator, a transmission line and a -1 MV insulating transformer for the ITER NBI power supply. The inverter frequency of 150 Hz in the -1 MV power supply and major circuit parameters have been proposed and adopted in the ITER NBI. The dc UHV insulation has been carefully designed since dc long pulse insulation is quite different from conventional ac insulation or dc short pulse systems. A multi-layer insulation structure of the transformer for a long pulse up to 3600 s has been designed with electric field simulation. Based on the simulation the overall dimensions of the dc UHV components have been finalized. A surge energy suppression system is also essential to protect the accelerator from electric breakdowns. The JADA contributes to provide an effective surge suppression system composed of core snubbers and resistors. Input energy into the accelerator from the power supply can be reduced to about 20 J, which satisfies the design criteria of 50 J in total in the case of breakdown at -1 MV.

  4. Controller for a High-Power, Brushless dc Motor

    Science.gov (United States)

    Fleming, David J.; Makdad, Terence A.

    1987-01-01

    Driving and braking torques controllable. Control circuit operates 7-kW, 45-lb-ft (61-N-m), three-phase, brushless dc motor in both motor and generator modes. In motor modes, energy from power source is pulse-width modulated to motor through modified "H-bridge" circuit, in generator mode, energy from motor is pulse-width modulated into bank of load resistors to provide variable braking torques. Circuit provides high-resolution torque control in both directions over wide range of speeds and torques. Tested successfully at bus voltages up to 200 Vdc and currents up to 45 A.

  5. Deposition of diamond-like carbon films by plasma source ion implantation with superposed pulse

    International Nuclear Information System (INIS)

    Baba, K.; Hatada, R.

    2003-01-01

    Diamond-like carbon (DLC) films were prepared on silicon wafer substrate by plasma source ion implantation with superposed negative pulse. Methane and acetylene gases were used as working gases for plasma. A negative DC voltage and a negative pulse voltage were superposed and applied to the substrate holder. The DC voltage was changed in the range from 0 to -4 kV and the pulse voltage was changed from 0 to -18 kV. The surface of DLC films was very smooth. The deposition rate of DLC films increased with increasing in superposed DC bias voltage. Carbon ion implantation was confirmed for the DLC film deposited from methane plasma with high pulse voltage. I D /I G ratios of Raman spectroscopy were around 1.5 independent on pulse voltage. The maximum hardness of 20.3 GPa was observed for the film prepared with high DC and high pulse voltage

  6. PUSPATI Triga Reactor pulsing parameters

    Energy Technology Data Exchange (ETDEWEB)

    Auu, Gui Ah; Abu, Puad Haji; Yunus, Yaziz [PUSPATI, Selangor (Malaysia)

    1984-06-01

    The pulsing experiment was carried out as part of the commissioning activites of PUSPATI TRIGA Reactor (PTR). Several parameters of PTR were deduced from the experiment. It was found that the maximum temperature of the fuel was far below the safety limit when the maximum allowable positive reactivity of $3.00 was inserted into the core. The peak power achieved was 1354 Mw.

  7. Nuclear magnetic resonance experiments with dc SQUID amplifiers

    International Nuclear Information System (INIS)

    Heaney, M.B.

    1990-11-01

    The development and fabrication of dc SQUIDs (Superconducting QUantum Interference Devices) with Nb/Al 2 O 3 /Nb Josephson junctions is described. A theory of the dc SQUID as a radio-frequency amplifier is presented, with an optimization strategy that accounts for the loading and noise contributions of the postamplifier and maximizes the signal-to-noise ratio of the total system. The high sensitivity of the dc SQUID is extended to high field NMR. A dc SQUID is used as a tuned radio-frequency amplifier to detect pulsed nuclear magnetic resonance at 32 MHz from a metal film in a 3.5 Tesla static field. A total system noise temperature of 11 K has been achieved, at a bath temperature of 4.2 K. The minimum number of nuclear Bohr magnetons observable from a free precession signal after a single pulse is about 2 x 10 17 in a bandwidth of 25 kHz. In a separate experiment, a dc SQUID is used as a rf amplifier in a NQR experiment to observe a new resonance response mechanism. The net electric polarization of a NaClO 3 crystal due to the precessing electric quadrupole moments of the Cl nuclei is detected at 30 MHz. The sensitivity of NMR and NQR spectrometers using dc SQUID amplifiers is compared to the sensitivity of spectrometers using conventional rf amplifiers. A SQUID-based spectrometer has a voltage sensitivity which is comparable to the best achieved by a FET-based spectrometer, at these temperatures and operating frequencies

  8. 75 FR 61989 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-8-31, DC-8-32, DC-8-33, DC-8-41...

    Science.gov (United States)

    2010-10-07

    ... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 8-31, DC-8-32, DC-8-33, DC-8-41, DC-8-42, and... to all of the McDonnell Douglas Corporation airplanes identified above. The existing AD currently... the following new airworthiness directive (AD): 2010-21-03 McDonnell Douglas Corporation: Amendment 39...

  9. Triple voltage dc-to-dc converter and method

    Science.gov (United States)

    Su, Gui-Jia

    2008-08-05

    A circuit and method of providing three dc voltage buses and transforming power between a low voltage dc converter and a high voltage dc converter, by coupling a primary dc power circuit and a secondary dc power circuit through an isolation transformer; providing the gating signals to power semiconductor switches in the primary and secondary circuits to control power flow between the primary and secondary circuits and by controlling a phase shift between the primary voltage and the secondary voltage. The primary dc power circuit and the secondary dc power circuit each further comprising at least two tank capacitances arranged in series as a tank leg, at least two resonant switching devices arranged in series with each other and arranged in parallel with the tank leg, and at least one voltage source arranged in parallel with the tank leg and the resonant switching devices, said resonant switching devices including power semiconductor switches that are operated by gating signals. Additional embodiments having a center-tapped battery on the low voltage side and a plurality of modules on both the low voltage side and the high voltage side are also disclosed for the purpose of reducing ripple current and for reducing the size of the components.

  10. Enhancing the Capacity of the AC Distribution System Using DC Interlinks - A Step Towards Future DC Grid

    DEFF Research Database (Denmark)

    Chaudhary, Sanjay; Guerrero, Josep M.; Teodorescu, Remus

    2015-01-01

    The development of distributed generation system and electric vehicles is bound to strain the distribution network. A typical radial distribution feeder suffers from the voltage fluctuation and feeder overload in the presence of a large amount of variable renewable generation. This paper presents...... a concept of enhancing the power handling capacity of distribution networks using dc grid interconnections. Control of both the active and reactive power exchange between the ac feeder and the interconnecting power converter has been proposed for the voltage regulation at the ac feeder terminal. Besides......, the dc grid interconnection also allows the introduction of a common storage system which can be shared by the connected ac feeders, and the dc grid connection to other renewable energy resources. The increased power handling capacity and improved voltage profile of the ac distribution feeder using...

  11. Bi-Directional DC-DC Converter for PHEV Applications

    Energy Technology Data Exchange (ETDEWEB)

    Abas Goodarzi

    2011-01-31

    Plug-In Hybrid Electric Vehicles (PHEV) require high power density energy storage system (ESS) for hybrid operation and high energy density ESS for Electric Vehicle (EV) mode range. However, ESS technologies to maximize power density and energy density simultaneously are not commercially feasible. The use of bi-directional DC-DC converter allows use of multiple energy storage, and the flexible DC-link voltages can enhance the system efficiency and reduce component sizing. This will improve fuel consumption, increase the EV mode range, reduce the total weight, reduce battery initial and life cycle cost, and provide flexibility in system design.

  12. Fast response double series resonant high-voltage DC-DC converter

    International Nuclear Information System (INIS)

    Lee, S S; Iqbal, S; Kamarol, M

    2012-01-01

    In this paper, a novel double series resonant high-voltage dc-dc converter with dual-mode pulse frequency modulation (PFM) control scheme is proposed. The proposed topology consists of two series resonant tanks and hence two resonant currents flow in each switching period. Moreover, it consists of two high-voltage transformer with the leakage inductances are absorbed as resonant inductor in the series resonant tanks. The secondary output of both transformers are rectified and mixed before supplying to load. In the resonant mode operation, the series resonant tanks are energized alternately by controlling two Insulated Gate Bipolar Transistor (IGBT) switches with pulse frequency modulation (PFM). This topology operates in discontinuous conduction mode (DCM) with all IGBT switches operating in zero current switching (ZCS) condition and hence no switching loss occurs. To achieve fast rise in output voltage, a dual-mode PFM control during start-up of the converter is proposed. In this operation, the inverter is started at a high switching frequency and as the output voltage reaches 90% of the target value, the switching frequency is reduced to a value which corresponds to the target output voltage. This can effectively reduce the rise time of the output voltage and prevent overshoot. Experimental results collected from a 100-W laboratory prototype are presented to verify the effectiveness of the proposed system.

  13. Fast pulse discriminator for photon counting at high photon densities

    International Nuclear Information System (INIS)

    Benoit, R.; Pedrini, A.

    1977-03-01

    A fast tunnel diode discriminator for photon counting up to 200MHz count frequency is described. The tunnel diode is operated on its apparent I.V. characteristics displayed when the diode is driven into its oscillating region. The pulse shaper-discriminator is completely D.C. coupled in order to avoid base-line shift at high pulse rates

  14. Process of DC-SC photoinjector

    International Nuclear Information System (INIS)

    Xiang Rong; Zhao Kui; Quan Shengwen; Ding Yuantao; Zhang Baocheng; Lu Xiangyang; Lin Lin; Wang Lifang; Chen Jiaer

    2004-01-01

    The DC-SC photoinjector at Beijing University is designed to provide an electron beam of average current 1 mA with the energy of 2-3 MeV and normalized rms transverse emittance of 3πmm-mrad at an 81.25 MHz repetition rate. The test facility has been completely installed in our lab. In this paper some of the ongoing experimental activities are summarized. First results from the cold test of superconducting cavity have been presented. According to the results, authors have improved the main coupler to repress the multipacting. The beam test of 100 μA on the DC gun has been done, photocathode preparation chamber can produce Cs 2 Te cathodes, and the laser system can provide laser pulse with 266 nm wavelength. The time synchronization between laser and RF power has been achieved by a timing stabilizer. A new method using 'due image pattern' of Cherenkov radiation will be commissioned to measure beam emittance. The next step is under way, to prepare all the equipment for the beam tests. (authors)

  15. RESONANT STEP-DOWN DC-DC POWER CONVERTERS

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention relates to a resonant step-down DC-DC power converter which comprises a primary side circuit and a secondary side circuit coupled through a galvanic isolation barrier. The primary side circuit comprises a positive and a negative input terminal for receipt of an input voltage...... charged from the input voltage and discharged to the output capacitor through the galvanic isolation barrier by a semiconductor switch arrangement in accordance with a switch control signal to produce the converter output voltage. The resonant step-down DC-DC power converter comprises an electrical short......-circuit connection across the galvanic isolation barrier connecting, in a first case, the second negative electrode of the output capacitor to the positive input terminal of the primary side circuit or, in a second case, connecting the second positive electrode of the output capacitor to the negative input terminal...

  16. Active pre-filters for dc/dc Boost regulators

    Directory of Open Access Journals (Sweden)

    Carlos Andrés Ramos-Paja

    2014-05-01

    Full Text Available This paper proposes an active pre-filter to mitigate the current harmonics generated by classical dc/dc Boost regulators, which generate current ripples proportional to the duty cycle. Therefore, high output voltage conditions, i.e., high voltage conversion ratios, produce high current harmonics that must be filtered to avoid damage or source losses. Traditionally, these current components are filtered using electrolytic capacitors, which introduce reliability problems because of their high failure rate. The solution introduced in this paper instead uses a dc/dc converter based on the parallel connection of the Boost canonical cells to filter the current ripples generated by the Boost regulator, improving the system reliability. This solution provides the additional benefits of improving the overall efficiency and the voltage conversion ratio. Finally, the solution is validated with simulations and experimental results.

  17. Influence of Bipolar Pulse Poling Technique for Piezoelectric Vibration Energy Harvesters using Pb(Zr,Ti)O3 Films on 200 mm SOI Wafers

    International Nuclear Information System (INIS)

    Moriwaki, N; Fujimoto, K; Suzuki, K; Kobayashi, T; Itoh, T; Maeda, R; Suzuki, Y; Makimoto, N

    2013-01-01

    Piezoelectric vibration energy harvester arrays using Pb(Zr,Ti)O 3 thin films on 200 mm SOI wafers were fabricated. In-plane distribution of influence of bipolar pulse poling technique on direct current (DC) power output from the harvesters was investigated. The results indicate that combination poling treatment of DC and bipolar pulse poling increases a piezoelectric property and reduces a dielectric constant. It means that this poling technique improves the figure of merit of sensors and harvesters. Maximum DC power from a harvester treated by DC poling after bipolar pulse poling is about five times larger than a one treated by DC poling only

  18. Linking DC together with TRSL

    DEFF Research Database (Denmark)

    Haxthausen, Anne Elisabeth; Yong, X.

    2000-01-01

    in a method for real-time developments. An operational semantics with behavior is specified for TRSL. It is defined what its means for a TRSL process to satisfy a DC requirement, and a method for verifying whether the satisfaction relation holds or not is provided. Our contribution also demonstrates a general......Duration Calculus (DC) is an interval-based real-time logic, which can be used in capturing and eliciting users' real-time requirements. The Timed RAISE Specification Language (TRSL) is an extension of the RAISE Specification Language with real-time features. This paper links DC and TRSL together...

  19. DC Microgrids—Part II

    DEFF Research Database (Denmark)

    Dragicevic, Tomislav; Lu, Xiaonan; Quintero, Juan Carlos Vasquez

    2016-01-01

    distribution applications such as traction, telecom, vehicular and distributed power systems can be classified under DC MG framework and ongoing development and expansion of the field is largely influenced by concepts used over there. This paper aims firstly to shed light on the practical design aspects of DC...... MG technology concerning typical power hardware topologies and their suitability for different emerging smart grid applications. Then, an overview of the state of the art in DC MG protection and grounding is provided. Owing to the fact that there is no zero current crossing, an arc that appears upon...

  20. DC-Compensated Current Transformer.

    Science.gov (United States)

    Ripka, Pavel; Draxler, Karel; Styblíková, Renata

    2016-01-20

    Instrument current transformers (CTs) measure AC currents. The DC component in the measured current can saturate the transformer and cause gross error. We use fluxgate detection and digital feedback compensation of the DC flux to suppress the overall error to 0.15%. This concept can be used not only for high-end CTs with a nanocrystalline core, but it also works for low-cost CTs with FeSi cores. The method described here allows simultaneous measurements of the DC current component.

  1. DC injection into low voltage AC networks

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    This report summarises the results of a study investigating the impact of levels of injected DC current injections on a low voltage AC distribution network systems in order to recommend acceptable limits of DC from microgeneration. Relevant literature is reviewed, and the impact of DC levels in distribution transformers, transformer modelling, and instrumental transformers are discussed. The impact of DC in residual current devices (RCD) and in domestic electricity watt hour meters is examined along with DC enhanced corrosion, corrosion failure, and the measurement of DC current injection. Sources of DC injection outlined include DC from computer power supplies, network faults, geomagnetic phenomena, lighting circuits/dimmers, and embedded generators.

  2. Isolated step-down DC -DC converter for electric vehicles

    Science.gov (United States)

    Kukovinets, O. V.; Sidorov, K. M.; Yutt, V. E.

    2018-02-01

    Modern motor-vehicle industrial sector is moving rapidly now towards the electricity-driving cars production, improving their range and efficiency of components, and in particular the step-down DC/DC converter to supply the onboard circuit 12/24V of electric vehicle from the high-voltage battery. The purpose of this article - to identify the best circuitry topology to design an advanced step-down DC/DC converters with the smallest mass, volume, highest efficiency and power. And this will have a positive effect on driving distance of electric vehicle (EV). On the basis of computational research of existing and implemented circuit topologies of step-down DC/DC converters (serial resonant converter, full bridge with phase-shifting converter, LLC resonant converter) a comprehensive analysis was carried out on the following characteristics: specific volume, specific weight, power, efficiency. The data obtained was the basis for the best technical option - LLC resonant converter. The results can serve as a guide material in the process of components design of the traction equipment for electric vehicles, providing for the best technical solutions in the design and manufacturing of converting equipment, self-contained power supply systems and advanced driver assistance systems.

  3. Polymeric electrochemical element for adaptive networks: Pulse mode

    International Nuclear Information System (INIS)

    Smerieri, Anteo; Berzina, Tatiana; Erokhin, Victor; Fontana, M. P.

    2008-01-01

    An electrochemically controlled polymeric heterojunction working as a memristor, i.e., having memory properties, was investigated in pulse mode, mimicking synaptic behavior of signal transmission in biological systems. Influence of parameters such as pulse duration, interval between pulses, and value of potential base level was analyzed. Learning capabilities were shown to be reversible and repeatable for both potentiation and inhibition of signal transmission. The adaptive behavior of the element was investigated and was shown to be more efficient than the dc mode

  4. Investigations Of A Pulsed Cathodic Vacuum Arc

    Science.gov (United States)

    Oates, T. W. H.; Pigott, J.; Denniss, P.; Mckenzie, D. R.; Bilek, M. M. M.

    2003-06-01

    Cathodic vacuum arcs are well established as a method for producing thin films for coatings and as a source of metal ions. Research into DC vacuum arcs has been going on for over ten years in the School of Physics at the University of Sydney. Recently a project was undertaken in the school to design and build a pulsed CVA for use in the investigation of plasma sheaths and plasma immersion ion implantation. Pulsed cathodic vacuum arcs generally have a higher current and plasma density and also provide a more stable and reproducible plasma density than their DC counterparts. Additionally it has been shown that if a high repetition frequency can be established the deposition rate of pulsed arcs is equal to or greater than that of DC arcs with a concomitant reduction in the rate of macro-particle formation. We present here results of our investigations into the building of a center-triggered pulsed cathodic vacuum arc. The design of the power supply and trigger mechanism and the geometry of the anode and cathode are examined. Observations of type I and II arc spots using a CCD camera, and cathode spot velocity dependence on arc current will be presented. The role of retrograde motion in a high current pulsed arc is discussed.

  5. Investigations Of A Pulsed Cathodic Vacuum Arc

    International Nuclear Information System (INIS)

    Oates, T.W.H.; Pigott, J.; Denniss, P.; Mckenzie, D.R.; Bilek, M.M.M.

    2003-01-01

    Cathodic vacuum arcs are well established as a method for producing thin films for coatings and as a source of metal ions. Research into DC vacuum arcs has been going on for over ten years in the School of Physics at the University of Sydney. Recently a project was undertaken in the school to design and build a pulsed CVA for use in the investigation of plasma sheaths and plasma immersion ion implantation. Pulsed cathodic vacuum arcs generally have a higher current and plasma density and also provide a more stable and reproducible plasma density than their DC counterparts. Additionally it has been shown that if a high repetition frequency can be established the deposition rate of pulsed arcs is equal to or greater than that of DC arcs with a concomitant reduction in the rate of macro-particle formation. We present here results of our investigations into the building of a center-triggered pulsed cathodic vacuum arc. The design of the power supply and trigger mechanism and the geometry of the anode and cathode are examined. Observations of type I and II arc spots using a CCD camera, and cathode spot velocity dependence on arc current will be presented. The role of retrograde motion in a high current pulsed arc is discussed

  6. Borehole DC-12 hydrostratigraphic chart

    International Nuclear Information System (INIS)

    Gephart, R.E.

    1981-09-01

    This hydrostratigraphic chart identifies the basic stratigraphy and preliminary hydrologic testing results for Borehole DC-12. This borehole was cored through the Saddle Mountains and Wanapum basalt formations and into the Grande Ronde. Selected zones were hydrologically tested during coring

  7. Borehole DC-14 hydrostratigraphic chart

    International Nuclear Information System (INIS)

    Gephart, R.E.

    1981-09-01

    This hydrostratigraphic chart identifies the basic stratigraphy and preliminary hydrologic testing results for Borehole DC-14. This borehole was cored through the Saddle Mountains and Wanapum basalt formations and into the Grande Ronde. Selected zones were hydrologically tested during coring

  8. Borehole DC-15 hydrostratigraphic chart

    International Nuclear Information System (INIS)

    Gephart, R.E.

    1981-09-01

    This hydrostratigraphic chart identifies the basic stratigraphy and preliminary hydrologic testing results for Borehole DC-15. This borehole was cored through the Saddle Mountains and Wanapum basalt formations and into the Grande Ronde. Selected zones were hydrologically tested during coring

  9. Reactive Systems

    DEFF Research Database (Denmark)

    Aceto, Luca; Ingolfsdottir, Anna; Larsen, Kim Guldstrand

    A reactive system comprises networks of computing components, achieving their goals through interaction among themselves and their environment. Thus even relatively small systems may exhibit unexpectedly complex behaviours. As moreover reactive systems are often used in safety critical systems......, the need for mathematically based formal methodology is increasingly important. There are many books that look at particular methodologies for such systems. This book offers a more balanced introduction for graduate students and describes the various approaches, their strengths and weaknesses, and when...... they are best used. Milner's CCS and its operational semantics are introduced, together with the notions of behavioural equivalences based on bisimulation techniques and with recursive extensions of Hennessy-Milner logic. In the second part of the book, the presented theories are extended to take timing issues...

  10. Five-Level Active-Neutral-Point-Clamped DC/DC Converter for Medium-Voltage DC Grids

    DEFF Research Database (Denmark)

    Liu, Dong; Deng, Fujin; Chen, Zhe

    2017-01-01

    This paper proposes a five-level active-neutralpoint- clamped (5L-ANPC) dc/dc converter for applications in medium voltage dc (MVDC) grids. A modulation strategy is proposed for the 5L-ANPC dc/dc converter to generate multilevel voltage waveforms, which can effectively reduce voltage change rate dv...... effectively eliminate high voltage leaps caused by the dead time effect. In addition, a capacitor voltage control strategy is proposed for the 5L-ANPC dc/dc converter to ensure the balanced flying capacitor voltage and desired five-level voltage waveforms. Finally, simulation and experimental studies...

  11. Constant DC-Capacitor Voltage-Control-Based Harmonics Compensation Strategy of Smart Charger for Electric Vehicles in Single-Phase Three-Wire Distribution Feeders

    Directory of Open Access Journals (Sweden)

    Fuka Ikeda

    2017-06-01

    Full Text Available This paper discusses harmonic current compensation of the constant DC-capacitor voltage-control (CDCVC-based strategy of smart chargers for electric vehicles (EVs in single-phase three-wire distribution feeders (SPTWDFs under nonlinear load conditions. The basic principle of the CDCVC-based harmonics compensation strategy under nonlinear load conditions is discussed in detail. The instantaneous power flowing into the three-leg pulse-width modulated (PWM rectifier, which performs as a smart charger, shows that the CDCVC-based strategy achieves balanced and sinusoidal source currents with a unity power factor. The CDCVC-based harmonics compensation strategy does not require any calculation blocks of fundamental reactive, unbalanced active, and harmonic currents. Thus, the authors propose a simplified algorithm to compensate for reactive, unbalanced active, and harmonic currents. A digital computer simulation is implemented to confirm the validity and high practicability of the CDCVC-based harmonics compensation strategy using PSIM software. Simulation results demonstrate that balanced and sinusoidal source currents with a unity power factor in SPTWDFs are obtained on the secondary side of the pole-mounted distribution transformer (PMDT during both the battery-charging and discharging operations in EVs, compensating for the reactive, unbalanced active, and harmonic currents.

  12. 75 FR 63040 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-30, DC...

    Science.gov (United States)

    2010-10-14

    ... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 10-10, DC-10-10F, DC-10-30, DC-10-30F (KDC-10... following new airworthiness directive (AD): 2010-21-13 McDonnell Douglas Corporation: Amendment 39-16473... November 18, 2010. Affected ADs (b) None. Applicability (c) This AD applies to McDonnell Douglas...

  13. 75 FR 68246 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-15, DC...

    Science.gov (United States)

    2010-11-05

    ...-1044; Directorate Identifier 2010-NM-033-AD] RIN 2120-AA64 Airworthiness Directives; McDonnell Douglas..., 2007) and adding the following new AD: McDonnell Douglas Corporation: Docket No. FAA-2010-1044.... Applicability (c) This AD applies to all McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-15, DC...

  14. Whole tumor antigen vaccination using dendritic cells: Comparison of RNA electroporation and pulsing with UV-irradiated tumor cells

    Directory of Open Access Journals (Sweden)

    Benencia Fabian

    2008-04-01

    Full Text Available Abstract Because of the lack of full characterization of tumor associated antigens for solid tumors, whole antigen use is a convenient approach to tumor vaccination. Tumor RNA and apoptotic tumor cells have been used as a source of whole tumor antigen to prepare dendritic cell (DC based tumor vaccines, but their efficacy has not been directly compared. Here we compare directly RNA electroporation and pulsing of DCs with whole tumor cells killed by ultraviolet (UV B radiation using a convenient tumor model expressing human papilloma virus (HPV E6 and E7 oncogenes. Although both approaches led to DCs presenting tumor antigen, electroporation with tumor cell total RNA induced a significantly higher frequency of tumor-reactive IFN-gamma secreting T cells, and E7-specific CD8+ lymphocytes compared to pulsing with UV-irradiated tumor cells. DCs electroporated with tumor cell RNA induced a larger tumor infiltration by T cells and produced a significantly stronger delay in tumor growth compared to DCs pulsed with UV-irradiated tumor cells. We conclude that electroporation with whole tumor cell RNA and pulsing with UV-irradiated tumor cells are both effective in eliciting antitumor immune response, but RNA electroporation results in more potent tumor vaccination under the examined experimental conditions.

  15. A Zero-Voltage Switching Control Strategy for Dual Half-Bridge Cascaded Three-Level DC/DC Converter with Balanced Capacitor Voltages

    DEFF Research Database (Denmark)

    Liu, Dong; Wang, Yanbo; Chen, Zhe

    2017-01-01

    The input capacitor's voltages are unbalanced under the conventional control strategy in a dual half-bridge cascaded three-level (TL) DC/DC converter, which would affect the high voltage stresses on the capacitors. This paper proposes a pulse-wide modulation (PWM) strategy with two working modes...... for the dual half-bridge cascaded TL DC/DC converter, which can realize the zero-voltage switching (ZVS). More significantly, a capacitor voltage balance control is proposed by alternating the two working modes of the proposed ZVS PWM strategy, which can eliminate the voltage unbalance on the four input...... capacitors. Therefore, the proposed control strategy can improve the converter's performances in: 1) reducing the switching losses and noises of the power switches; and 2) reducing the voltage stresses on the input capacitors. Finally, the simulation results are conducted to verify the proposed control...

  16. Gate Driver Circuit of Power Electronic Switches with Reduced Number of Isolated DC/DC Converter for a Switched Reluctance Motor

    International Nuclear Information System (INIS)

    Memon, A.A.

    2013-01-01

    This paper presents a gate driver circuit for the switching devices used in the asymmetrical converter for a switched reluctance machine with reduced number of isolated dc/dc converters. Isolation required in the gate driver circuit of switching devices is indispensable. For the purpose of isolation different arrangements may be used such as pulse transformers. The dc/dc converter for isolation and powering the gate drive circuits is suitable, cheaper in cost and simple to implement. It is also significant that required number of isolation converters is much less than the switches used in converter. In addition, a simple logic circuit has been presented for producing the gate signals at correct phase sequence which is compared with the gated signals directly obtained from the encoder of an existing machine. (author)

  17. Kinetic studies on a repetitively pulsed fast reactor

    International Nuclear Information System (INIS)

    Das, S.

    1982-01-01

    Neutronic analysis of an earlier proposed periodically pulsed fast reactor at Kalpakkam (KPFR) has been carried out numerically under equilibrium and transient conditions using the one-point model of reactor kinetics and the experimentally measured total worth of reactivity modulator, the parabolic coefficient of reactivity of the movable reflector and the mean prompt neutron lifetime. Results of steady-state calculations - treated on the basis of delayed neutron precursor and energy balances during a period of operation - have been compared with the analytical formulae of Larrimore for a parabolic reactivity input. Empirical relations for half-width of the fast neutron pulse, the peak pulse power and the power at first crossing of prompt criticality have been obtained and shown to be accurate enough for predicting steady-state power pulse characteristics of a periodically pulsed fast reactor. The concept of a subprompt-critical reactor has been used to calculate the fictitious delayed neutron fraction, β of the KPFR through a numerical experiment. Relative pulse height stability and pulse shape sensitivity to changes of maximum reactivity is discussed. With the aid of new safety concepts, the Power Amplification Factor (PAF) and the Pulse Growth Factor (Rsub(p)), the dynamics KPFR under accidental conditions has been studied for step and ramp reactivity perturbations. All the analysis has been done without taking account of reactivity feedback. (orig.)

  18. Pulsewidth modulated DC-to-DC power conversion circuits, dynamics, and control designs

    CERN Document Server

    Choi, Byungcho

    2013-01-01

    This is the definitive reference for anyone involved in pulsewidth modulated DC-to-DC power conversion Pulsewidth Modulated DC-to-DC Power Conversion: Circuits, Dynamics, and Control Designs provides engineers, researchers, and students in the power electronics field with comprehensive and complete guidance to understanding pulsewidth modulated (PWM) DC-to-DC power converters. Presented in three parts, the book addresses the circuitry and operation of PWM DC-to-DC converters and their dynamic characteristics, along with in-depth discussions of control design of PWM DC-to

  19. Atmel Microcontroller Based Soft Switched PWM ZVS Full Bridge DC to DC Converter

    Directory of Open Access Journals (Sweden)

    DEEPAK KUMAR NAYAK

    2010-12-01

    Full Text Available This paper deals with the simulation and implementation of soft switched PWM ZVS full bridge DC to DC converter. The 48V DC is efficiently reduced to 12V DC using a DC to DC converter. This converter has advantages like reduced switching losses, stresses and EMI. Input DC is converted into high frequency AC and it is stepped down to 12V level. Later it is rectified using a full wave rectifier. Laboratory model of microcontroller based DC to DC converter is fabricated and tested. The experimental results are compared with the simulation results.

  20. 75 FR 60602 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-15, DC...

    Science.gov (United States)

    2010-10-01

    ... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 10-10, DC-10-10F, DC-10-15, DC-10-30, DC-10... adding the following new AD: 2010-20-14 McDonnell Douglas Corporation: Amendment 39-16449. Docket No. FAA... the airplanes identified in paragraphs (c)(1) and (c)(2) of this AD. (1) McDonnell Douglas Corporation...

  1. 75 FR 6160 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-15, DC...

    Science.gov (United States)

    2010-02-08

    ...-0032; Directorate Identifier 2009-NM-213-AD] RIN 2120-AA64 Airworthiness Directives; McDonnell Douglas...: McDonnell Douglas Corporation: Docket No. FAA-2010-0032; Directorate Identifier 2009-NM-213-AD. Comments Due... applies to McDonnell Douglas Corporation Model DC- 10-10, DC-10-10F, DC-10-15, DC-10-30, DC-10-30F (KC-10A...

  2. 75 FR 38943 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-30, DC...

    Science.gov (United States)

    2010-07-07

    ...-0672; Directorate Identifier 2010-NM-047-AD] RIN 2120-AA64 Airworthiness Directives; McDonnell Douglas...: McDonnell Douglas Corporation: Docket No. FAA-2010-0672; Directorate Identifier 2010-NM-047-AD. Comments Due... applies to McDonnell Douglas Corporation Model DC- 10-10, DC-10-10F, DC-10-30, DC-10-30F (KDC-10), DC-10...

  3. Light-weight DC to very high voltage DC converter

    Science.gov (United States)

    Druce, R.L.; Kirbie, H.C.; Newton, M.A.

    1998-06-30

    A DC-DC converter capable of generating outputs of 100 KV without a transformer comprises a silicon opening switch (SOS) diode connected to allow a charging current from a capacitor to flow into an inductor. When a specified amount of charge has flowed through the SOS diode, it opens up abruptly; and the consequential collapsing field of the inductor causes a voltage and current reversal that is steered into a load capacitor by an output diode. A switch across the series combination of the capacitor, inductor, and SOS diode closes to periodically reset the SOS diode by inducing a forward-biased current. 1 fig.

  4. Light-weight DC to very high voltage DC converter

    Energy Technology Data Exchange (ETDEWEB)

    Druce, Robert L. (Union City, CA); Kirbie, Hugh C. (Dublin, CA); Newton, Mark A. (Livermore, CA)

    1998-01-01

    A DC-DC converter capable of generating outputs of 100 KV without a transformer comprises a silicon opening switch (SOS) diode connected to allow a charging current from a capacitor to flow into an inductor. When a specified amount of charge has flowed through the SOS diode, it opens up abruptly; and the consequential collapsing field of the inductor causes a voltage and current reversal that is steered into a load capacitor by an output diode. A switch across the series combination of the capacitor, inductor, and SOS diode closes to periodically reset the SOS diode by inducing a forward-biased current.

  5. Radiated electromagnetic emissions of DC-DC converters

    International Nuclear Information System (INIS)

    Feld, L; Jussen, R; Karpinski, W; Klein, K; Sammet, J; Wlochal, M

    2010-01-01

    For the CMS tracker at SLHC a new powering scheme is considered to be mandatory to allow the detector to provide at least the same performance as today at the LHC. The baseline solution of CMS foresees the use of DC-DC converters to provide larger currents with smaller losses. An important component of most converters are inductors which, however, tend to radiate the switching noise generated by the converter. The emissions of different inductors have been measured and simulated, the coil design has been optimized and noise susceptibility measurements, with present CMS hardware, have been performed. This article summarizes the results.

  6. DESIGN OPTIMIZATION OF RESONANT DC-DC CONVERTERS

    OpenAIRE

    Belqasem Aljafari

    2016-01-01

    Resonant DC/DC converters are the class of converters, which have L-C resonant tank serving as a major part of the power conversion process. The fundamental concept of the resonant converter is that the circulating energy in an L-C resonant circuit is manageable by changing the operating frequency, and therefore the converter can condition the input power to the desired output voltage. The development in power conversion technology is steady demand for high power efficiency and high power den...

  7. DC grid for home applications

    Science.gov (United States)

    Elangovan, D.; Archana, R.; Jayadeep, V. J.; Nithin, M.; Arunkumar, G.

    2017-11-01

    More than fifty percent Indian population do not have access to electricity in daily lives. The distance between the power generating stations and the distribution centers forms one of the main reasons for lack of electrification in rural and remote areas. Here lies the importance of decentralization of power generation through renewable energy resources. In the present world, electricity is predominantly powered by alternating current, but most day to day devices like LED lamps, computers and electrical vehicles, all run on DC power. By directly supplying DC to these loads, the number of power conversion stages was reduced, and overall system efficiency increases. Replacing existing AC network with DC is a humongous task, but with power electronic techniques, this project intends to implement DC grid at a household level in remote and rural areas. Proposed work was designed and simulated successfully for various loads amounting to 250 W through appropriate power electronic convertors. Maximum utilization of the renewable sources for domestic and commercial application was achieved with the proposed DC topology.

  8. Linking DC together with TRSL

    DEFF Research Database (Denmark)

    Haxthausen, Anne; Yong, Xia

    1999-01-01

    In this talk we present a method for linking the Duration Calculus together with the Timed RAISE Specification Language. Duration Calculus (DC) [ZHR91] is an interval-based real time logic, which can be used naturally in capturing and eliciting users' real time requirements in the form of constra......In this talk we present a method for linking the Duration Calculus together with the Timed RAISE Specification Language. Duration Calculus (DC) [ZHR91] is an interval-based real time logic, which can be used naturally in capturing and eliciting users' real time requirements in the form.......TRSL is a real-time extension of the RAISE Specification Language (RSL) [Rlg92] which together with its associated method [Rmg95]and tools has shown to be very useful in the industrial development of software systems. Therefore, a promising approach for the development of real-time systemscould be to use DC...... for high-level specifications of real-time requirementsand TRSL for specifying real-time implementations in the form of timed communicating concurrent processes.In order to link DC and TRSL together in a well-founded way, we formally define what it means for a TRSL process to satisfy a DC requirement...

  9. Pulse plating

    CERN Document Server

    Hansal, Wolfgang E G; Green, Todd; Leisner, Peter; Reichenbach, Andreas

    2012-01-01

    The electrodeposition of metals using pulsed current has achieved practical importance in recent years. Although it has long been known that changes in potential, with or without polarity reversal, can significantly affect the deposition process, the practical application of this has been slow to be adopted. This can largely be explained in terms of the complex relationship between the current regime and its effect on the electrodeposition process. In order to harness these effects, an understanding of the anodic and cathodic electrochemical processes is necessary, together with the effects of polarity reversal and the rate of such reversals. In this new monograph, the basics of metal electrodeposition from solution are laid out in great detail in seven distinct chapters. With this knowledge, the reader is able to predict how a given pulse train profile can be adopted to achieve a desired outcome. Equally important is the choice of a suitable rectifier and the ancillary control circuits to enable pulse platin...

  10. Effects of microwave pulse-width damage on a bipolar transistor

    International Nuclear Information System (INIS)

    Ma Zhen-Yang; Chai Chang-Chun; Ren Xing-Rong; Yang Yin-Tang; Chen Bin; Zhao Ying-Bo

    2012-01-01

    This paper presents a theoretical study of the pulse-width effects on the damage process of a typical bipolar transistor caused by high power microwaves (HPMs) through the injection approach. The dependences of the microwave damage power, P, and the absorbed energy, E, required to cause the device failure on the pulse width τ are obtained in the nanosecond region by utilizing the curve fitting method. A comparison of the microwave pulse damage data and the existing dc pulse damage data for the same transistor is carried out. By means of a two-dimensional simulator, ISE-TCAD, the internal damage processes of the device caused by microwave voltage signals and dc pulse voltage signals are analyzed comparatively. The simulation results suggest that the temperature-rising positions of the device induced by the microwaves in the negative and positive half periods are different, while only one hot spot exists under the injection of dc pulses. The results demonstrate that the microwave damage power threshold and the absorbed energy must exceed the dc pulse power threshold and the absorbed energy, respectively. The dc pulse damage data may be useful as a lower bound for microwave pulse damage data. (interdisciplinary physics and related areas of science and technology)

  11. Design of double DC motor control system based on DSP

    Directory of Open Access Journals (Sweden)

    Suo WANG

    2017-10-01

    Full Text Available Aiming at the problems of speed control, commutation and so on in the multi-motor synchronous control system, based on automatic control technology, a control system with PC as principal computer and DSP as slave computer is designed, which can change dual DC motor speed and steering, as well as select work drive motors. Related hardware and software design of the control system are given. Through serial communication between DSP and PC using PC serial port software, digital control command is sent to the slave computer for controlling dual DC motor to do a series of preset functions. PWM pulse width modulation is used for motor speed regulation, photoelectric encoder is used to measure motor speed by T method, and the motor speed is displayed by the actual waveform. Experimental results show that the system can not only realize the synchronization of dual DC motor speed and steering adjustment, but also select the motor and achieve the dual DC motors synchronization control effect. The control system has certain reliability and effectiveness.

  12. Electroporation of DC-3F cells is a dual process.

    Science.gov (United States)

    Wegner, Lars H; Frey, Wolfgang; Silve, Aude

    2015-04-07

    Treatment of biological material by pulsed electric fields is a versatile technique in biotechnology and biomedicine used, for example, in delivering DNA into cells (transfection), ablation of tumors, and food processing. Field exposure is associated with a membrane permeability increase usually ascribed to electroporation, i.e., formation of aqueous membrane pores. Knowledge of the underlying processes at the membrane level is predominantly built on theoretical considerations and molecular dynamics (MD) simulations. However, experimental data needed to monitor these processes with sufficient temporal resolution are scarce. The whole-cell patch-clamp technique was employed to investigate the effect of millisecond pulsed electric fields on DC-3F cells. Cellular membrane permeabilization was monitored by a conductance increase. For the first time, to our knowledge, it could be established experimentally that electroporation consists of two clearly separate processes: a rapid membrane poration (transient electroporation) that occurs while the membrane is depolarized or hyperpolarized to voltages beyond so-called threshold potentials (here, +201 mV and -231 mV, respectively) and is reversible within ∼100 ms after the pulse, and a long-term, or persistent, permeabilization covering the whole voltage range. The latter prevailed after the pulse for at least 40 min, the postpulse time span tested experimentally. With mildly depolarizing or hyperpolarizing pulses just above threshold potentials, the two processes could be separated, since persistent (but not transient) permeabilization required repetitive pulse exposure. Conductance increased stepwise and gradually with depolarizing and hyperpolarizing pulses, respectively. Persistent permeabilization could also be elicited by single depolarizing/hyperpolarizing pulses of very high field strength. Experimental measurements of propidium iodide uptake provided evidence of a real membrane phenomenon, rather than a mere

  13. Modeling and analysis of fractional order DC-DC converter.

    Science.gov (United States)

    Radwan, Ahmed G; Emira, Ahmed A; AbdelAty, Amr M; Azar, Ahmad Taher

    2017-07-11

    Due to the non-idealities of commercial inductors, the demand for a better model that accurately describe their dynamic response is elevated. So, the fractional order models of Buck, Boost and Buck-Boost DC-DC converters are presented in this paper. The detailed analysis is made for the two most common modes of converter operation: Continuous Conduction Mode (CCM) and Discontinuous Conduction Mode (DCM). Closed form time domain expressions are derived for inductor currents, voltage gain, average current, conduction time and power efficiency where the effect of the fractional order inductor is found to be strongly present. For example, the peak inductor current at steady state increases with decreasing the inductor order. Advanced Design Systems (ADS) circuit simulations are used to verify the derived formulas, where the fractional order inductor is simulated using Valsa Constant Phase Element (CPE) approximation and Generalized Impedance Converter (GIC). Different simulation results are introduced with good matching to the theoretical formulas for the three DC-DC converter topologies under different fractional orders. A comprehensive comparison with the recently published literature is presented to show the advantages and disadvantages of each approach. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  14. An Integrated Multifunctional Bidirectional AC/DC and DC/DC Converter for Electric Vehicles Applications

    Directory of Open Access Journals (Sweden)

    Liwen Pan

    2016-06-01

    Full Text Available This paper presents an on-board vehicular battery charger that integrates bidirectional AC/DC converter and DC/DC converter to achieve high power density for application in electric vehicles (EVs. The integrated charger is able to transfer electrical energy between the battery pack and the electric traction system and to function as an AC/DC battery charger. The integrated charger topology is presented and the design of passive components is discussed. The control schemes are developed for motor drive system and battery-charging system with a power pulsation reduction circuit. Simulation results in MATLAB/Simulink and experiments on a 30-kW motor drive and 3.3-kW AC/DC charging prototype validate the performance of the proposed technology. In addition, power losses, efficiency comparison and thermal stress for the integrated charger are illustrated. The results of the analyses show the validity of the advanced integrated charger for electric vehicles.

  15. DC-STAMP Is an Osteoclast Fusogen Engaged in Periodontal Bone Resorption.

    Science.gov (United States)

    Wisitrasameewong, W; Kajiya, M; Movila, A; Rittling, S; Ishii, T; Suzuki, M; Matsuda, S; Mazda, Y; Torruella, M R; Azuma, M M; Egashira, K; Freire, M O; Sasaki, H; Wang, C Y; Han, X; Taubman, M A; Kawai, T

    2017-06-01

    Dendritic cell-specific transmembrane protein (DC-STAMP) plays a key role in the induction of osteoclast (OC) cell fusion, as well as DC-mediated immune regulation. While DC-STAMP gene expression is upregulated in the gingival tissue with periodontitis, its pathophysiological roles in periodontitis remain unclear. To evaluate the effects of DC-STAMP in periodontitis, anti-DC-STAMP-monoclonal antibody (mAb) was tested in a mouse model of ligature-induced periodontitis ( n = 6-7/group) where Pasteurella pneumotropica ( Pp)-reactive immune response activated T cells to produce receptor activator of nuclear factor kappa-B ligand (RANKL), which, in turn, promotes the periodontal bone loss via upregulation of osteoclastogenesis. DC-STAMP was expressed on the cell surface of mature multinuclear OCs, as well as immature mononuclear OCs, in primary cultures of RANKL-stimulated bone marrow cells. Anti-DC-STAMP-mAb suppressed the emergence of large, but not small, multinuclear OCs, suggesting that DC-STAMP is engaged in the late stage of cell fusion. Anti-DC-STAMP-mAb also inhibited pit formation caused by RANKL-stimulated bone marrow cells. Attachment of ligature to a second maxillary molar induced DC-STAMP messenger RNA and protein, along with elevated tartrate-resistant acid phosphatase-positive (TRAP+) OCs and alveolar bone loss. As we expected, systemic administration of anti-DC-STAMP-mAb downregulated the ligature-induced alveolar bone loss. Importantly, local injection of anti-DC-STAMP-mAb also suppressed alveolar bone loss and reduced the total number of multinucleated TRAP+ cells in mice that received ligature attachment. Attachment of ligature induced significantly elevated tumor necrosis factor-α, interleukin-1β, and RANKL in the gingival tissue compared with the control site without ligature ( P < 0.05), which was unaffected by local injection with either anti-DC-STAMP-mAb or control-mAb. Neither in vivo anti- Pp IgG antibody nor in vitro anti- Pp T

  16. Switching coordination of distributed dc-dc converters for highly efficient photovoltaic power plants

    Science.gov (United States)

    Agamy, Mohammed; Elasser, Ahmed; Sabate, Juan Antonio; Galbraith, Anthony William; Harfman Todorovic, Maja

    2014-09-09

    A distributed photovoltaic (PV) power plant includes a plurality of distributed dc-dc converters. The dc-dc converters are configured to switch in coordination with one another such that at least one dc-dc converter transfers power to a common dc-bus based upon the total system power available from one or more corresponding strings of PV modules. Due to the coordinated switching of the dc-dc converters, each dc-dc converter transferring power to the common dc-bus continues to operate within its optimal efficiency range as well as to optimize the maximum power point tracking in order to increase the energy yield of the PV power plant.

  17. Speed Control Analysis of Brushless DC Motor Based on Maximum Amplitude DC Current Feedback

    Directory of Open Access Journals (Sweden)

    Hassan M.A.A.

    2014-07-01

    Full Text Available This paper describes an approach to develop accurate and simple current controlled modulation technique for brushless DC (BLDC motor drive. The approach is applied to control phase current based on generation of quasi-square wave current by using only one current controller for the three phases. Unlike the vector control method which is complicated to be implemented, this simple current modulation technique presents advantages such as phase currents are kept in balance and the current is controlled through only one dc signal which represent maximum amplitude value of trapezoidal current (Imax. This technique is performed with Proportional Integral (PI control algorithm and triangular carrier comparison method to generate Pulse Width Modulation (PWM signal. In addition, the PI speed controller is incorporated with the current controller to perform desirable speed operation of non-overshoot response. The performance and functionality of the BLDC motor driver are verified via simulation by using MATLAB/SIMULINK. The simulation results show the developed control system performs desirable speed operation of non-overshoot and good current waveforms.

  18. A Comprehensive Analysis and Hardware Implementation of Control Strategies for High Output Voltage DC-DC Boost Power Converter

    Directory of Open Access Journals (Sweden)

    Sanjeevikumar Padmanaban

    2017-01-01

    Full Text Available Classical DC-DC converters used in high voltage direct current (HVDC power transmission systems, lack in terms of efficiency, reduced transfer gain and increased cost with sensor (voltage/current numbers. Besides, the internal self-parasitic behavior of the power components reduces the output voltage and efficiency of classical HV converters. This paper deals with extra high-voltage (EHV dc-dc boost converter by the application of voltage-lift technique to overcome the aforementioned deficiencies. The control strategy is based on classical proportional-integral (P-I and fuzzy logic closed-loop controller to get high and stable output voltage. Complete hardware prototype of EHV is implemented and experimental tasks are carried out with digital signal processor (DSP TMS320F2812. The control algorithms P-I, fuzzy logic and the pulse-width modulation (PWM signals for N-channel MOSFET device are performed by the DSP. The experimental results provided show good conformity with developed hypothetical predictions. Additionally, the presented study confirms that the fuzzy logic controller provides better performance than classical P-I controller under different perturbation conditions.

  19. PUSPATI Triga Reactor pulsing parameters

    International Nuclear Information System (INIS)

    Gui Ah Auu; Puad Haji Abu; Yaziz Yunus

    1984-01-01

    The pulsing experiment was carried out as part of the commissioning activites of PUSPATI TRIGA Reactor (PTR). Several parameters of PTR were deduced from the experiment. It was found that the maximum temperature of the fuel was far below the safety limit when the maximum allowable positive reactivity of $3.00 was inserted into the core. The peak power achieved was 1354 Mw. (author)

  20. PIII Plasma Density Enhancement by a New DC Power Source

    International Nuclear Information System (INIS)

    Lopez-Callejas, R.; Godoy-Cabrera, O. G.; Granda-Gutierrez, E. E.; Piedad-Beneitez, A. de la; Munoz-Castro, A. E.; Valencia A, R.; Barocio, S. R.; Mercado-Cabrera, A.; Pena-Eguiluz, R.

    2006-01-01

    In practical terms, those plasmas produced by a DC voltage power supply do not attain densities above the 108 to 109 cm-3 band. Here we present a power supply, controlled in current and voltage, which has been successfully designed and constructed delivering plasma densities in the orders of 109 - 1010 cm-3. Its experimental performance test was conducted within one toroidal and one cylindrical chambers capable of 29 and 35 litres, respectively, using nitrogen gas. The DC plasma was characterized by a double electric probe. Several physical phenomena present in the PIII process have been keenly investigated including plasma sheath dynamics, interaction of plasma and surface, etc. In this paper we analyze the effect of the implantation voltage, plasma density and pulse time in the PIII average heating power and fluence density

  1. Application of Distributed DC/DC Electronics in Photovoltaic Systems

    Science.gov (United States)

    Kabala, Michael

    In a typical residential, commercial or utility grade photovoltaic (PV) system, PV modules are connected in series and in parallel to form an array that is connected to a standard DC/AC inverter, which is then connected directly to the grid. This type of standard installation; however, does very little to maximize the energy output of the solar array if certain conditions exist. These conditions could include age, temperature, irradiance and other factors that can cause mismatch between PV modules in an array that severely cripple the output power of the system. Since PV modules are typically connected in series to form a string, the output of the entire string is limited by the efficiency of the weakest module. With PV module efficiencies already relatively low, it is critical to extract the maximum power out of each module in order to make solar energy an economically viable competitor to oil and gas. Module level DC/DC electronics with maximum power point (MPP) tracking solves this issue by decoupling each module from the string in order for the module to operate independently of the geometry and complexity of the surrounding system. This allows each PV module to work at its maximum power point by transferring the maximum power the module is able to deliver directly to the load by either boosting (stepping up) the voltage or bucking (stepping down) the voltage. The goal of this thesis is to discuss the development of a per-module DC/DC converter in order to maximize the energy output of a PV module and reduce the overall cost of the system by increasing the energy harvest.

  2. The Measurement of Reactivity In Multiregion Subcritical Systems by the Pulsed Neutron Technique; Mesure de la Reactivite dans les Systemes Sous-Critiques a Plusieurs Regions par la Methode des Neutrons Pulses; Izmerenie reaktivnosti v mnogozonnykh podkriticheskikh sistemakh metodom impul'snykh nejtronov; Mediciones de la Reactividad en Sistemas Subcriticos de Varias Regiones Mediante la Tecnica de los Neutrones Pulsados

    Energy Technology Data Exchange (ETDEWEB)

    Sherwin, J.; Leng, J. H. [United Kingdom Atomic Energy Authority, Windscale Works, Cumberland (United Kingdom)

    1965-10-15

    The prompt decay of a thermalized burst of neutrons in a multiregion subcritical system is examined using a two-group diffusion theory. It is shown that a relationship can be established between the prompt decay constant of the fundamental mode and the effective multiplication factor of the system in terms of two parameters, defined, for the purposes of this paper, as the reactor response coefficient and the prompt decay correction and which depend to a large extent on the spatial flux patterns within the system. For the uniform bare system, the response coefficient can be identified with the mean neutron lifetime in the system; for a multiregion system it represents a compound of the lifetimes in each region weighted by perturbation type integrals. The second parameter, the decay correction, can have no physical meaning in that it arises from an attempt to relate the two scales of reactivity involved; that is the scale using the prompt decay constant and the scale derived using the effective multiplication factor. The properties of these parameters are examined here with reference to an enriched uranium graphitemoderated reactor consisting of uniform core and reflector and it is shown that the two parameters are not uniquely defined by the reactivity of the system but depend on the method chosen to make the system subcritical. Two sets of measurements are treated by the theory. In one, the Windscale Advanced Gas-Cooled Reactor was shut down by a uniform poison. In the other the reactivity of a core in the zero-energy reactor HERO was varied by altering the loaded radius. The neutron pulse measurements are all shown to be in good agreement with more conventional methods of reactivity determination. Some discussion of the experimental techniques and the difficulties encountered in the graphite-moderated systems is presented. (author) [French] Les auteurs etudient la decroissance des neutrons instantanes d'une bouffee thermalisee de neutrons dans un systeme sous

  3. Design of a high power, resonant converter for DC wind turbines

    DEFF Research Database (Denmark)

    Dincan, Catalin Gabriel; Kjær, Philip Carne; Chen, Yu-Hsing

    2018-01-01

    This paper presents a design procedure and loss estimation for a high power, medium voltage series resonant converter (entitled SRC#), intended for application in megawatt medium-voltage DC wind turbines. The converter is operated with a novel method of operation, entitled pulse removal technique...

  4. Robust method for stator current reconstruction from DC link in a ...

    African Journals Online (AJOL)

    Using the switching signals and dc link current, this paper presents a new algorithm for the reconstruction of stator currents of an inverter-fed, three-phase induction motor drive. Unlike the classical and improved methods available in literature, the proposed method is neither based on pulse width modulation pattern ...

  5. Voltage Weak DC Distribution Grids

    NARCIS (Netherlands)

    Hailu, T.G.; Mackay, L.J.; Ramirez Elizondo, L.M.; Ferreira, J.A.

    2017-01-01

    This paper describes the behavior of voltage weak DC distribution systems. These systems have relatively small system capacitance. The size of system capacitance, which stores energy, has a considerable effect on the value of fault currents, control complexity, and system reliability. A number of

  6. Compact integrated dc SQUID gradiometer

    Science.gov (United States)

    de Waal, V. J.; Klapwijk, T. M.

    1982-10-01

    An all-niobium integrated system of first-order gradiometer and dc suprconducting quantum interference device (SQUID) has been developed. It is relatively simple to fabricate, has an overall size of 17×12 mm and a sensitivity of 3.5×10-12 T m-1 Hz-1/2.

  7. Compact integrated dc SQUID gradiometer

    Energy Technology Data Exchange (ETDEWEB)

    de Waal, V.J.; Klapwijk, T.M.

    1982-10-01

    An all-niobium integrated system of first-order gradiometer and dc suprconducting quantum interference device (SQUID) has been developed. It is relatively simple to fabricate, has an overall size of 17 x 12 mm and a sensitivity of 3.5 x 10/sup -12/ T m/sup -1/ Hz/sup -1/2/.

  8. Experiments with a DC Motor

    Science.gov (United States)

    Kraftmakher, Yaakov

    2010-01-01

    Experiments with an electric motor provide good opportunity to demonstrate some basic laws of electricity and magnetism. The aim of the experiments with a low-power dc motor is to show how the motor approaches its steady rotation and how its torque, mechanical power and efficiency depend on the rotation velocity. The tight relationship between the…

  9. Borehole DC-6 hydrostratigraphic chart

    International Nuclear Information System (INIS)

    Gephart, R.E.

    1981-09-01

    This hydrostratigraphic chart for Borehole DC-6 identifies the basic stratigraphy and preliminary hydrologic test results. This borehole was cored for obtaining stratigraphic data and only that portion within the Grande Ronde formation remains open for hydrologic testing. The upper two formations were cased and cemented off

  10. Startup experience with the MFTF-B ECRH 100 kV dc power supply

    International Nuclear Information System (INIS)

    Bishop, S.R.; Goodman, R.A.; Wilson, J.H.

    1983-01-01

    One of the 24 Accel dc Power Supplies (ADCPS) originally intended for the Mirror Fusion Test Facility (MFTF-B) Neutral Beam Power Supply (NBPS) System has been converted to provide negative polarity output at 90 kV with a load current of 64 A dc. The load duty cycle is a pulse of 30-seconds duration with a pulse repetition period of five minutes. A new control system has been built which will serve as a prototype for the MFTF-B ADCPS controls, and a test setup was built which will be used to test the ADCPS. The Electron Cyclotron Resonance Heating (ECRH) dc Power Supply (DCPS) has been tested under both no-load and dummy-load conditions, under remote control, without notable problems. Test results indicate that the power supply should be reliable and safe to operate, and will meet the load duty requirements

  11. Startup experience with the MFTF-B ECRH 100 kV dc power supply

    International Nuclear Information System (INIS)

    Bishop, S.R.; Goodman, R.A.; Wilson, J.H.

    1983-01-01

    One of the 24 Accel DC Power Supplies (ADCPS) originally intended for the Mirror Fusion Test Facility (MFTF-B) Neutral Beam Power Supply (NBPS) System has been converted to provide negative polarity output at 90 kV with a load current of 64 A dc. The load duty cycle is a pulse of 30-seconds duration with a pulse repetition period of five minutes. A new control system has been built which will serve as a prototype for the MFTF-B ADCPS controls, and a test setup was built which will be used to test the ADCPS. The Electron Cyclotron Resonance Heating (ECRH) DC Power Supply (DCPS) has been tested under both no-load and dummy-load conditions, under remote control, without notable problems. Test results indicate that the power supply should be reliable and safe to operate, and will meet the load duty requirements

  12. Construction of double discharge pulsed electron beam generator and its applications

    International Nuclear Information System (INIS)

    Goektas, H.

    2001-12-01

    Generation of fast pulsed electron beam by superposing DC and pulsed hollow cathode discharge is studied. The electrical characteristics and measurements of the electron beam generator are done dc glow discharge and for the pulsed one. The electron beam current, its density and magnetic field effect, pinch effect, have been studied. The dependence of the electron beam parameters with respect to pressure and magnetic field have been studied. The pulsing effect of the beam is reviewed. By using the generator, micron holes drilling and carbon deposition was done at the laboratory. As a target source for carbon deposition methane gas is used and for Hydrogen-free carbon deposition was graphite

  13. Pulsed laser illumination of photovoltaic cells

    Science.gov (United States)

    Yater, Jane A.; Lowe, Roland A.; Jenkins, Phillip P.; Landis, Geoffrey A.

    1995-01-01

    In future space missions, free electron lasers (FEL) may be used to illuminate photovoltaic receivers to provide remote power. Both the radio-frequency (RF) and induction FEL produce pulsed rather than continuous output. In this work we investigate cell response to pulsed laser light which simulates the RF FEL format. The results indicate that if the pulse repetition is high, cell efficiencies are only slightly reduced compared to constant illumination at the same wavelength. The frequency response of the cells is weak, with both voltage and current outputs essentially dc in nature. Comparison with previous experiments indicates that the RF FEL pulse format yields more efficient photovoltaic conversion than does an induction FEL format.

  14. Peptide-loaded dendritic cells prime and activate MHC-class I-restricted T cells more efficiently than protein-loaded cross-presenting DC

    DEFF Research Database (Denmark)

    Met, Ozcan; Buus, Søren; Claesson, Mogens H

    2003-01-01

    -pulsed DC. Moreover, SIINFEKL-loaded DC were up to 50 times more efficient than DC-pulsed with OVA-protein for generation of an H-2K(b)-restricted response. Immunization of mice with SIINFEKL-loaded DC resulted in a much stronger H-2K(b)-restricted response than immunization with OVA-pulsed DC. These data......Undifferentiated and differentiated dendritic cells (uDC and dDC, respectively), derived from the bone marrow, were studied in vitro and in vivo. Ovalbumin (OVA) and two OVA-derived peptides binding to H-2K(b) and I-A(b), respectively, were used. Two IL-2 secreting T cell hybridomas specific...... for the OVA-derived epitopes were used in the in vitro read-out. The ability to cross-present the H-2K(b) binding OVA(257-264)-peptide (SIINFEKL) was restricted to dDC, which express CD11c(+), CD86(+), and MHC-II(+). In vitro, the antigenicity of SIINFEKL-loaded DC declined at a slower rate than that of OVA...

  15. Pulsed power

    International Nuclear Information System (INIS)

    Anon.

    1977-01-01

    The key element of our pulsed power program is concentration of power in time and space by suppression of breakdown in dielectrics and in vacuum. Magnetically insulated vacuum transmission lines and magnetic suppression of insulator flashover have continued as the main reserch directions. Vacuum insulated line studies at Physics International have been expanded and a test bed at Sandia, called MITE (Magnetically Insulated Transmission Experiment), is under development. The choice for the baseline EBFA design will depend on the outcome of these studies and should be made in July 1977. The slow and intermediate speed pulsed power approaches to EBFA will be based on Proto I and Proto II results and several of the projected EBFA subsystems are presently being tested in Proto II. A further stage of power concentration, within the vacuum diode itself, would considerably ease the burden on dielectrics; methods of power multiplication involving magnetically imploded plasmas are being considered and tests have begun using the Ripple III apparatus

  16. DC to DC power converters and methods of controlling the same

    Science.gov (United States)

    Steigerwald, Robert Louis; Elasser, Ahmed; Sabate, Juan Antonio; Todorovic, Maja Harfman; Agamy, Mohammed

    2012-12-11

    A power generation system configured to provide direct current (DC) power to a DC link is described. The system includes a first power generation unit configured to output DC power. The system also includes a first DC to DC converter comprising an input section and an output section. The output section of the first DC to DC converter is coupled in series with the first power generation unit. The first DC to DC converter is configured to process a first portion of the DC power output by the first power generation unit and to provide an unprocessed second portion of the DC power output of the first power generation unit to the output section.

  17. A Single-Chip CMOS Pulse Oximeter with On-Chip Lock-In Detection

    OpenAIRE

    Diwei He; Stephen P. Morgan; Dimitrios Trachanis; Jan van Hese; Dimitris Drogoudis; Franco Fummi; Francesco Stefanni; Valerio Guarnieri; Barrie R. Hayes-Gill

    2015-01-01

    Pulse oximetry is a noninvasive and continuous method for monitoring the blood oxygen saturation level. This paper presents the design and testing of a single-chip pulse oximeter fabricated in a 0.35 ?m CMOS process. The chip includes photodiode, transimpedance amplifier, analogue band-pass filters, analogue-to-digital converters, digital signal processor and LED timing control. The experimentally measured AC and DC characteristics of individual circuits including the DC output voltage of the...

  18. High frequency pulse anodising of magnetron sputtered Al–Zr and Al–Ti Coatings

    DEFF Research Database (Denmark)

    Gudla, Visweswara Chakravarthy; Bordo, Kirill; Engberg, Sara

    2016-01-01

    High frequency pulse anodising of Al–Zr and Al–Ti coatings is studied as a surface finishing technique and compared to conventional decorative DC anodising. The Al–Zr and Al–Ti coatings were deposited using DC magnetron sputtering and were heat treated after deposition to generate a multiphase mi...

  19. Dilation and Curettage (D&C)

    Science.gov (United States)

    ... For Patients About ACOG Dilation and Curettage (D&C) Home For Patients Search FAQs Dilation and Curettage ( ... February 2016 PDF Format Dilation and Curettage (D&C) Special Procedures What is dilation and curettage (D& ...

  20. Design and performance of PEP dc-power systems

    International Nuclear Information System (INIS)

    Jackson, T.

    1981-03-01

    The PEP Magnet Power Supply System represents a significant departure from previous technology with the goal of improved performance at lower cost. In nineteen of the magnet families around the ring, Chopper power supplies are used. The many choppers are powered from two 2 MW dc supplies, and control the average power to the various magnet loads by pulse-width modulation at a 2 kilohertz repetition rate. Each chopper utilizes SCR's for switching, and stores sufficient capacitive energy for turn-off on command. Most of the energy is recirculated, resulting in high-efficiency. The two kilohertz chopping rate allows a one kilohertz unity-gain bandwidth in the current-regulator loop, and this wide bandwidth, coupled with low drift components in the error-detection system, provides a high-performance system. The PEP system has also shown that the chopper system is economical compared to standard multi-pulse controlled-rectifier

  1. Hierarchical Power Sharing Control in DC Microgrids

    DEFF Research Database (Denmark)

    Peyghami, Saeed; Mokhtari, Hossein; Blaabjerg, Frede

    2016-01-01

    Because of the advances in power electronics, DC-based power systems, have been used in industrial applications such as data centers [18], space applications [10], aircraft [12], offshore wind farms, electric vehicles [56], DC home systems [5, 20], and high-voltage DC transmission systems...

  2. Pulsed corona generation using a diode-based pulsed power generator

    Science.gov (United States)

    Pemen, A. J. M.; Grekhov, I. V.; van Heesch, E. J. M.; Yan, K.; Nair, S. A.; Korotkov, S. V.

    2003-10-01

    Pulsed plasma techniques serve a wide range of unconventional processes, such as gas and water processing, hydrogen production, and nanotechnology. Extending research on promising applications, such as pulsed corona processing, depends to a great extent on the availability of reliable, efficient and repetitive high-voltage pulsed power technology. Heavy-duty opening switches are the most critical components in high-voltage pulsed power systems with inductive energy storage. At the Ioffe Institute, an unconventional switching mechanism has been found, based on the fast recovery process in a diode. This article discusses the application of such a "drift-step-recovery-diode" for pulsed corona plasma generation. The principle of the diode-based nanosecond high-voltage generator will be discussed. The generator will be coupled to a corona reactor via a transmission-line transformer. The advantages of this concept, such as easy voltage transformation, load matching, switch protection and easy coupling with a dc bias voltage, will be discussed. The developed circuit is tested at both a resistive load and various corona reactors. Methods to optimize the energy transfer to a corona reactor have been evaluated. The impedance matching between the pulse generator and corona reactor can be significantly improved by using a dc bias voltage. At good matching, the corona energy increases and less energy reflects back to the generator. Matching can also be slightly improved by increasing the temperature in the corona reactor. More effective is to reduce the reactor pressure.

  3. Characterising and modelling extended conducted electromagnetic interference in densely packed DC-DC converter

    CSIR Research Space (South Africa)

    Grobler, Inus

    2013-09-01

    Full Text Available . The military specified DC-DC converters are applicable, spanning from 100 W handheld power managers up to 2 kW DC-DC battery chargers. Circuit layout high frequency effects as well as high frequency impedances of the power components were characterised...

  4. Full wave dc-to-dc converter using energy storage transformers

    Science.gov (United States)

    Moore, E. T.; Wilson, T. G.

    1969-01-01

    Full wave dc-to-dc converter, for an ion thrustor, uses energy storage transformers to provide a method of dc-to-dc conversion and regulation. The converter has a high degree of physical simplicity, is lightweight and has high efficiency.

  5. A DC-DC Conversion Powering Scheme for the CMS Phase-1 Pixel Upgrade

    CERN Document Server

    Feld, Lutz Werner; Marcel Friedrichs; Richard Hensch; Karpinski, Waclaw; Klein, Katja; Sammet, Jan Domenik; Wlochal, Michael

    2012-01-01

    The powering scheme of the CMS pixel detector will be described, and the performance of prototype DC-DC buck converters will be presented, including power efficiency, system tests with DC-DC converters and pixel modules, thermal management, reliability at low temperature, and studies of potential frequency locking betwe...

  6. Transformerless dc-Isolated Converter

    Science.gov (United States)

    Rippel, Wally E.

    1987-01-01

    Efficient voltage converter employs capacitive instead of transformer coupling to provide dc isolation. Offers buck/boost operation, minimal filtering, and low parts count, with possible application in photovoltaic power inverters, power supplies and battery charges. In photovoltaic inverter circuit with transformerless converter, Q2, Q3, Q4, and Q5 form line-commutated inverter. Switching losses and stresses nil because switching performed when current is zero.

  7. AC-DC PFC Converter Using Combination of Flyback Converter and Full-bridge DC-DC Converter

    Directory of Open Access Journals (Sweden)

    Moh. Zaenal Efendi

    2014-06-01

    Full Text Available This paper presents a combination of power factor correction converter using Flyback converter and Full-bridge dc-dc converter in series connection. Flyback converter is operated in discontinuous conduction mode so that it can serve as a power factor correction converter and meanwhile Full-bridge dc-dc converter is used for dc regulator. This converter system is designed to produce a 86 Volt of output voltage and 2 A of output current. Both simulation and experiment results show that the power factor of this converter achieves up to 0.99 and meets harmonic standard of IEC61000-3-2. Keywords: Flyback Converter, Full-bridge DC-DC Converter, Power Factor Correction.

  8. A Feed-Forward Control Realizing Fast Response for Three-Branch Interleaved DC-DC Converter in DC Microgrid

    Directory of Open Access Journals (Sweden)

    Haojie Wang

    2016-07-01

    Full Text Available It is a common practice for storage batteries to be connected to DC microgrid buses through DC-DC converters for voltage support on islanded operation mode. A feed-forward control based dual-loop constant voltage PI control for three-branch interleaved DC-DC converters (TIDC is proposed for storage batteries in DC microgrids. The working principle of TIDC is analyzed, and the factors influencing the response rate based on the dual-loop constant voltage control for TIDC are discussed, and then the method of feed-forward control for TIDC is studied to improve the response rate for load changing. A prototype of the TIDC is developed and an experimental platform is built. The experiment results show that DC bus voltage sags or swells caused by load changing can be reduced and the time for voltage recovery can be decreased significantly with the proposed feed-forward control.

  9. A Feed-Forward Control Realizing Fast Response for Three-Branch Interleaved DC-DC Converter in DC Microgrid

    DEFF Research Database (Denmark)

    Wang, Haojie; Han, Minxiao; Yan, Wenli

    2016-01-01

    It is a common practice for storage batteries to be connected to DC microgrid buses through DC-DC converters for voltage support on islanded operation mode. A feed-forward control based dual-loop constant voltage PI control for three-branch interleaved DC-DC converters (TIDC) is proposed...... for storage batteries in DC microgrids. The working principle of TIDC is analyzed, and the factors influencing the response rate based on the dual-loop constant voltage control for TIDC are discussed, and then the method of feed-forward control for TIDC is studied to improve the response rate for load...... changing. A prototype of the TIDC is developed and an experimental platform is built. The experiment results show that DC bus voltage sags or swells caused by load changing can be reduced and the time for voltage recovery can be decreased significantly with the proposed feed-forward control....

  10. A single-phase PWM controlled AC to DC converter based on control of unity displacement power factor

    OpenAIRE

    Funabiki, Shigeyuki

    1990-01-01

    A modified pulse-width modulation (PWM) technique that improves the displacement power factor and the input power factor of a single-phase AC to DC converter is discussed. The modified converter is shown to have a high input power factor and allows the of DC voltage from zero to more than the maximum value of the source voltage. The displacement power factor is unity, and the input power factor is almost unity in the wide range of current command

  11. The reactivity meter and core reactivity

    International Nuclear Information System (INIS)

    Siltanen, P.

    1999-01-01

    This paper discussed in depth the point kinetic equations and the characteristics of the point kinetic reactivity meter, particularly for large negative reactivities. From a given input signal representing the neutron flux seen by a detector, the meter computes a value of reactivity in dollars (ρ/β), based on inverse point kinetics. The prompt jump point of view is emphasised. (Author)

  12. FLYWHEEL AND A DC MACHINE

    Directory of Open Access Journals (Sweden)

    IVAN ALCALÁ

    2014-01-01

    Full Text Available Este artículo describe el análisis, modelado y simulación de un vehículo eléctrico (EV enfocado al desarrollo de un banco de pruebas para reproducir la dinámica del EV. El banco está formado por un drive de motor de inducción (IM acoplado directamente a una máquina de DC y a un volante de inercia a través de una transmisión. El volante de inercia y la máquina de DC reproducen la dinámica y las fuerzas que actúan en el vehículo. Se propone una metodología para diseñar un banco de pruebas de EV para estudiar el comportamiento de vehículos eléctricos cercano a las condiciones de operación reales. El análisis de las fuerzas en el EV en conjunto con la máquina DC define las condiciones de operación del EV. El modelado y la simulación son desarrollados en MATLAB/Simulink, el banco de pruebas implementado es controlado por un DSP. Finalmente, los resultados de simulación y experimentales obtenidos validan el funcionamiento del banco de prueba.

  13. Effects of pulse-to-pulse residual species on discharges in repetitively pulsed discharges through packed bed reactors

    Science.gov (United States)

    Kruszelnicki, Juliusz; Engeling, Kenneth W.; Foster, John E.; Kushner, Mark J.

    2016-09-01

    Atmospheric pressure dielectric barrier discharges (DBDs) sustained in packed bed reactors (PBRs) are being investigated for conversion of toxic and waste gases, and CO2 removal. These discharges are repetitively pulsed having varying flow rates and internal geometries, which results in species from the prior pulse still being in the discharge zone at the time the following discharge pulse occurs. A non-negligible residual plasma density remains, which effectively acts as preionization. This residual charge changes the discharge properties of subsequent pulses, and may impact important PBR properties such as chemical selectivity. Similarly, the residual neutral reactive species produced during earlier pulses will impact the reaction rates on subsequent pulses. We report on results of a computational investigation of a 2D PBR using the plasma hydrodynamics simulator nonPDPSIM. Results will be discussed for air flowing though an array of dielectric rods at atmospheric pressure. The effects of inter-pulse residual species on PBR discharges will be quantified. Means of controlling the presence of residual species in the reactor through gas flow rate, pulse repetition, pulse width and geometry will be described. Comparisons will be made to experiments. Work supported by US DOE Office of Fusion Energy Science and the National Science Foundation.

  14. PULSE COLUMN

    Science.gov (United States)

    Grimmett, E.S.

    1964-01-01

    This patent covers a continuous countercurrent liquidsolids contactor column having a number of contactor states each comprising a perforated plate, a layer of balls, and a downcomer tube; a liquid-pulsing piston; and a solids discharger formed of a conical section at the bottom of the column, and a tubular extension on the lowest downcomer terminating in the conical section. Between the conical section and the downcomer extension is formed a small annular opening, through which solids fall coming through the perforated plate of the lowest contactor stage. This annular opening is small enough that the pressure drop thereacross is greater than the pressure drop upward through the lowest contactor stage. (AEC)

  15. Pulse radiolysis

    International Nuclear Information System (INIS)

    Greenshields, H.; Seddon, W.A.

    1982-03-01

    This supplement to two bibliographies published in 1970 and 1972 lists 734 references to the literature of pulse radiolysis, arranged under eight broad subject headings. The references were compiled by searching Biological Abstracts, Chemical Abstracts, Nuclear Science Abstracts and the Weekly List of Papers in Radiation Chemistry issued by the Radiation Chemistry Data Center of Notre Dame University. Full bibliographic data is given for papers published in the period 1971 to 1974. A personal author index listing more than 600 authors and a similar number of co-authors is included

  16. Quasi-Z-Source Half-Bridge DC-DC Converter for Photovoltaic Applications

    OpenAIRE

    Vinnikov, D; Chub, A; Husev, O; Zaķis, J

    2015-01-01

    This paper presents a novel quasi-Z-source halfbridge galvanically isolated DC-DC converter intended for the photovoltaic applications. The topology could be envisioned as an alternative to the boost half-bridge DC-DC converter but the benefit of its symmetric structure reduces the threat of transformer saturation due to the dc flux. The proposed converter features the continuous input current and could be used either with one or two input voltage sources.

  17. Control of the DC-DC Converter used into Energy Generation System

    International Nuclear Information System (INIS)

    Bizon, Nicu; Oproescu, Mihai

    2006-01-01

    This paper presents an investigation of the DC-DC Converter controller used into Energy Generation System. The full bridge is used into an Energy Generation System (EGS) as second power interface between the energy source and the high DC bus. The simulation results show that the DC-DC Converter behavior can be improved using a well designed PI control surface. The used Simulink models for the EGS blocks and some design considerations are presented, too. (authors)

  18. Pulse pile-up. I: Short pulses

    International Nuclear Information System (INIS)

    Wilkinson, D.H.

    1990-07-01

    The search for rare large pulses against an intense background of smaller ones involves consideration of pulse pile-up. Approximate methods are presented, based on ruin theory, by which the probability of such pile-up may be estimated for pulses of arbitrary form and of arbitrary pulse-height distribution. These methods are checked against cases for which exact solutions are available. The present paper is concerned chiefly with short pulses of finite total duration. (Author) (5 refs., 24 figs.)

  19. A compact nanosecond pulse generator for DBD tube characterization

    Science.gov (United States)

    Rai, S. K.; Dhakar, A. K.; Pal, U. N.

    2018-03-01

    High voltage pulses of very short duration and fast rise time are required for generating uniform and diffuse plasma under various operating conditions. Dielectric Barrier Discharge (DBD) has been generated by high voltage pulses of short duration and fast rise time to produce diffuse plasma in the discharge gap. The high voltage pulse power generators have been chosen according to the requirement for the DBD applications. In this paper, a compact solid-state unipolar pulse generator has been constructed for characterization of DBD plasma. This pulsar is designed to provide repetitive pulses of 315 ns pulse width, pulse amplitude up to 5 kV, and frequency variation up to 10 kHz. The amplitude of the output pulse depends on the dc input voltage. The output frequency has been varied by changing the trigger pulse frequency. The pulsar is capable of generating pulses of positive or negative polarity by changing the polarity of pulse transformer's secondary. Uniform and stable homogeneous dielectric barrier discharge plasma has been produced successfully in a xenon DBD tube at 400-mbar pressure using the developed high voltage pulse generator.

  20. Calculation of concentration profiles and their experimental verification with a pulsed sieve-plate column and the reactive material system of uranyl nitrate, nitric acid/tributyl phosphate, kerosine

    International Nuclear Information System (INIS)

    Ihle, E.

    1985-01-01

    The present study is concerned with the calculation of stationary and non-stationary concentration profiles as well as with the starting and disturbance behaviour of a pulsed sieve-plate extraction column. It investigates into the material system HNO 3 /uranyl nitrate in water with 30 per cent by volume of tributyl phosphate in kerosine. During the measurements of the concentration profiles for HNO 3 transition, which were effected in the direction of extraction and reextraction, it was shown that the concentration profiles measured in the mixer-settler range, in spite of a sixfold enlargement of the specific heat transfer area, do not differ essentially from those measured in the dispersion range. During the measurements of concentration profiles for HNO 3 /uranium transition, which were effected in the direction of coextraction and co-reextraction only for mixer-settler range, it was discovered that with increasing phase ratios, there is a depletion of the uranium concentration in the aqueous phase. If the phase ratio is further raised, it is the nitric acid, and not the uranium, that is depleted. (orig./PW) [de

  1. ZVS Operating Region of Multiresonant DC/DC Boost Conveter

    Directory of Open Access Journals (Sweden)

    Elzbieta Szychta

    2007-01-01

    Full Text Available Electromagnetic phenomena that occur during stable operation in resonant circuits of multiresonant ZVS boost converter are described, which can be applied in many fields of the needs of DC voltage electricity. The operating region of the converter is defined which assures the circuit’s operation in which semiconductor elements are switched at zero voltage (ZVS. Conditions delimiting the ZVS operating region are provided. Analysis of the circuit’s operation is based on results of simulation testing by means of Simplorer software.

  2. Development of a dc, broad beam, Mevva ion source

    International Nuclear Information System (INIS)

    Brown, I.G.; Dickinson, M.R.; Galvin, J.E.; MacGill, R.A.

    1991-09-01

    We are developing an embodiment of metal vapor vacuum arc (Mevva) ion source which will operate dc and have very large area beam. In preliminary testing, a dc titanium ion beam was formed with a current of approximately 0.6 amperes at an extraction voltage of 9kV (about 18 keV ion energy, by virtue of the ion charge state distribution) and using an 18 cm diameter set of multi-aperture. Separately, we have tested and formed beam from a 50 cm diameter (2000 cm 2 ) set of grids using a pulsed plasma gun. This configuration appears to be very efficient in terms of plasma utilization, and we have formed beams with diameter 33 cm (FWHM) and ion current up to 7 amperes at an extraction voltage of 50 kV (about 100 keV mean ion energy) and up to 20 amperes peak at the current overshoot part of the beam pulse. Here we describe this Part Of our Mevva development program and summarize the results obtained to-date

  3. A Feedback Passivation Design for DC Microgrid and Its DC/DC Converters

    Directory of Open Access Journals (Sweden)

    Feifan Ji

    2016-12-01

    Full Text Available There are difficulties in analyzing the stability of microgrids since they are located on various network structures. However, considering that the network often consists of passive elements, the passivity theory is applied in this paper to solve the above-mentioned problem. It has been formerly shown that when the network is weakly strictly positive real (WSPR, the DC microgrid is stable if all interfaces between the microgrid and converters are made to be passive, which is called interface passivity. Then, the feedback passivation method is proposed for the controller design of various DC–DC converters to achieve the interface passivity. The interface passivity is different from the passivity of closed-loop systems on which the passivity based control (PBC concentrates. The feedback passivation design is detailed for typical buck converters and boost converters in terms of conditions that the controller parameters should satisfy. The theoretical results are verified by a hardware-in-loop real-time labotray (RTLab simulation of a DC microgrid with four generators.

  4. Artificial neural network control of sab dc/dc converter

    International Nuclear Information System (INIS)

    Mahar, M.A.; Abro, M.R.; Larik, A.S.

    2009-01-01

    The latest development of power semiconductor devices enable the modern power electronic converters to withstand high voltage and high power applications. Power electronic converters are mostly periodic variable structure systems due to their switched operations. The main drawback of these converters is the generation of oscillations which are developed during the operation of the converters under nonlinear situations. To handle these nonlinearities, various researchers have proposed different control techniques. Power electronic designers are devoting in the further development of converter topologies and their control techniques. SAB (Single Active Bridge) DC/DC converter is a new topology recently introduced by Demetriades. This topology is used in high voltage and high power applications. Because of its smart features, SAB converter has recently drawn attention of many researchers. However, during the operation of SAB converter severe oscillations are generated. In this research work, a novel NNC (Neural Network Controller) model is developed for SAB converter to minimize oscillations generated during its operation. NNC is believed to be an advanced nonlinear and robust controller which has the ability to map the nonlinear behaviour in a negligible response time. The performance of SAB converter with NNC is tested under dynamic region by considering the reference voltage variation and duty ratio variation. The SAB converter is implemented and simulated in MATLAB/Simulink. The simulated results are presented. (author)

  5. Optimal Operation of Photovoltaic System with a DC-DC Boost Converter FED SAF Using ICosφ Algorithm

    Directory of Open Access Journals (Sweden)

    G.Vijayakumar

    2014-07-01

    Full Text Available This paper presents an optimal utilization of Photovoltaic (PV solar system based Shunt Active Filter (PV-SAF for harmonic mitigation, real and reactive power compensation at the point of common coupling (PCC throughout the day. This PV system operated SAF reduces the energy consumption by disconnecting the utility grid from the load through semiconductor switches, when the PV system generates excessive or equal real power to the required load demand. However, the reduction of energy consumption is always desirable for the reduction of panel tariff and global warming gasses. The PV module is connected to the DC side of SAF through the DC-DC converter with fuzzy based Perturb & Observe (P&O Maximum Power Point Tracking (MPPT algorithm to eliminate the drawback of the conventional PV system by tracking maximum power point of the PV array is presented. The reference currents extract by the Fuzzy logic controller based ICosΦ control strategy. This proposed PV-SAF, if connected at the terminals of a small industry or a home or a small enlightening institution can avoid interruptible power supply, use of individual stabilizer and potential panel tariff over a 12 hour period. A MATLAB simulink is presented to validate the advantage of the proposed system.

  6. Experiments with a dc motor

    International Nuclear Information System (INIS)

    Kraftmakher, Yaakov

    2010-01-01

    Experiments with an electric motor provide good opportunity to demonstrate some basic laws of electricity and magnetism. The aim of the experiments with a low-power dc motor is to show how the motor approaches its steady rotation and how its torque, mechanical power and efficiency depend on the rotation velocity. The tight relationship between the mechanical and electrical parameters of the motor is clearly seen. The measurements are carried out with the ScienceWorkshop data-acquisition system and the DataStudio software from PASCO scientific. The experiments are well related to university courses of electricity and magnetism and can be used in undergraduate laboratories or for lecture demonstrations.

  7. Resonance reduction for AC drives with small capacitance in the DC link

    DEFF Research Database (Denmark)

    Máthé, Lászlo; Török, Lajos; Wang, Dong

    2016-01-01

    Pulse Width Modulated AC drives equipped with small DC-link capacitor are becoming an attractive solution for electric drive applications with moderate requirements for shaft dynamic performance. However, when these drives are fed from a weak grid a resonance between the line side impedance...... and the DC-link capacitor appears. Due to this resonance, the THD and the partially weighted harmonic distortion of the line currents are increased, which may rise compatibility problems with the AC line harmonic standards. By using vector control the motor drive is transformed into a constant power load...

  8. Evolution of the Al2O3/Ge(1 0 0) interface for reactively sputter-deposited films submitted to postdeposition anneals

    Science.gov (United States)

    Bom, Nicolau Molina; Soares, Gabriel Vieira; Krug, Cristiano; Pezzi, Rafael Peretti; Baumvol, Israel Jacob Rabin; Radtke, Claudio

    2012-05-01

    Al2O3 was deposited by pulsed DC reactive sputter on Ge(1 0 0) aiming at producing layers with reduced OH and H2O content in comparison with water-based atomic layer deposition. In this way, the intrinsic interaction of Al2O3 with Ge could be probed. Photoelectron spectroscopy showed evidence of a GeO2 interlayer in as-deposited samples. Thermal annealing in Ar or forming gas for 30 min at 350 °C reduced the amount of oxidized Ge, i.e. significant activity took place at the Al2O3/Ge interface irrespective of annealing ambient. The remaining transition layer consisted essentially of aluminum germanates. Analysis of Si companion samples indicates that in the absence of an oxidizing agent, Al2O3/Ge is more stable than Al2O3/Si.

  9. Using PBL to Improve Educational Outcomes and Student Satisfaction in the Teaching of DC/DC and DC/AC Converters

    Science.gov (United States)

    Martinez-Rodrigo, Fernando; Herrero-De Lucas, Luis Carlos; de Pablo, Santiago; Rey-Boue, Alexis B.

    2017-01-01

    This paper examines the question of how to use project-based learning to increase student performance and satisfaction in a power electronics course addressing the topics of dc/dc and dc/ac converters, the assembly of a dc/dc converter, and the use of a commercial speed drive. A detailed presentation of the methodology is shown, and the results…

  10. The Topologies Research of a Soft Switching Bidirectional DC/DC Converter

    DEFF Research Database (Denmark)

    Zhang, Qi; Zhang, Yongping; Sun, Xiangdong

    2017-01-01

    A soft-switching solution implemented to the traditional bidirectional DC/DC converter is developed. The soft-switching cell, which composed of three auxiliary switches, one resonant capacitor and one resonant inductor, is equipped in the traditional bidirectional DC/DC converter to realize circuit...... circle. And the proposed topology of bidirectional soft-switching dc-dc converter(TASBC) performs ideal soft switching at boost operations. The characteristics of the proposed converter has been verified by MATLAB simulations and experimental results....

  11. Elimination of output voltage oscillations in DC-DC converter using PWM with PI controller

    Directory of Open Access Journals (Sweden)

    Sreenivasappa Veeranna Bhupasandra

    2010-01-01

    Full Text Available In this paper the SIMULINK model of a PWM controlled DC-DC converter is modeled using switching function concept to control the speed of the DC motor. The presence of the voltage oscillation cycles due to higher switching frequency in the DC-DC converter is identified. The effect of these oscillations on the output voltage of the converter, Armature current, Developed torque and Speed of the DC motor is analyzed. In order to minimize the oscillation cycles the PI controller is proposed in the PWM controller.

  12. Chaos analysis and chaotic EMI suppression of DC-DC converters

    CERN Document Server

    Zhang, Bo

    2014-01-01

    Introduces chaos theory, its analytical methods and the means to apply chaos to the switching power supply design DC-DC converters are typical switching systems which have plenty of nonlinear behaviors, such as bifurcation and chaos. The nonlinear behaviors of DC-DC converters have been studied heavily over the past 20 years, yet researchers are still unsure of the practical application of bifurcations and chaos in switching converters. The electromagnetic interference (EMI), which resulted from the high rates of changes of voltage and current, has become a major design criterion in DC-DC co

  13. Reactivity estimation for subcritical and critical reactors

    International Nuclear Information System (INIS)

    Benhaim A; Bellino P; Gomez A

    2012-01-01

    We developed a digital reactimeter that works in both current and pulse mode. This reactimeter will allow to estimate the reactivity of the reactor at any state. We st obtained for the measurements taken in the experimental reactor RA-1 the reactivity around the critical state without a neutron source. Measurements were made using simultaneously a compensated ionization chamber and a 3He proportional counter. The results were compared with the ones obtained from the digital reactimeter of reference with matching results within the experimental errors (author)

  14. Simultaneous distribution of AC and DC power

    Science.gov (United States)

    Polese, Luigi Gentile

    2015-09-15

    A system and method for the transport and distribution of both AC (alternating current) power and DC (direct current) power over wiring infrastructure normally used for distributing AC power only, for example, residential and/or commercial buildings' electrical wires is disclosed and taught. The system and method permits the combining of AC and DC power sources and the simultaneous distribution of the resulting power over the same wiring. At the utilization site a complementary device permits the separation of the DC power from the AC power and their reconstruction, for use in conventional AC-only and DC-only devices.

  15. Drilling history core hole DC-8

    International Nuclear Information System (INIS)

    1978-10-01

    Core hole DC-8 was completed in August, 1978 by Boyles Brothers Drilling Company, Spokane, Washington, under subcontract to Fenix and Scission, Inc. The hole was cored for the US Department of Energy and the Rockwell Hanford Operations' Basalt Waste Isolation Program. Fenix and Scisson, Inc. furnished the engineering, daily supervision of the core drilling activities, and geologic core logging for hole DC-8. Core hole DC-8 is located on the Hanford Site near the Wye Barricade and 50 feet northwest of rotary hole DC-7. The Hanford Site vation coordinates for DC-8 are North 14,955.94 feet and West 14,861.92 coordinates for DC-8 are North 14,955.94 feet and West 14,861.92 mean sea level. The purpose of core hole DC-8 was to core drill vertically through the basalt and interbed units for stratigraphic depth determination and core collection, and to provide a borehole for hydrologic testing and cross-hole seismic shear and pressure wave velocity studies with rotary hole DC-7. The total depth of core hole DC-8 was 4100.5 feet. Core recovery exceeded 97 percent of the total footage cored

  16. Drilling history core hole DC-8

    Energy Technology Data Exchange (ETDEWEB)

    1978-10-01

    Core hole DC-8 was completed in August, 1978 by Boyles Brothers Drilling Company, Spokane, Washington, under subcontract to Fenix and Scission, Inc. The hole was cored for the US Department of Energy and the Rockwell Hanford Operations' Basalt Waste Isolation Program. Fenix and Scisson, Inc. furnished the engineering, daily supervision of the core drilling activities, and geologic core logging for hole DC-8. Core hole DC-8 is located on the Hanford Site near the Wye Barricade and 50 feet northwest of rotary hole DC-7. The Hanford Site vation coordinates for DC-8 are North 14,955.94 feet and West 14,861.92 coordinates for DC-8 are North 14,955.94 feet and West 14,861.92 mean sea level. The purpose of core hole DC-8 was to core drill vertically through the basalt and interbed units for stratigraphic depth determination and core collection, and to provide a borehole for hydrologic testing and cross-hole seismic shear and pressure wave velocity studies with rotary hole DC-7. The total depth of core hole DC-8 was 4100.5 feet. Core recovery exceeded 97 percent of the total footage cored.

  17. Wide Temperature Range DC-DC Boost Converters for Command/Control/Drive Electronics, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — We shall develop wide temperature range DC-DC boost converters that can be fabricated using commercial CMOS foundries. The boost converters will increase the low...

  18. Modular Power System Configured with Standard Product Hybrid DC-DC Converters, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — VPT proposes an innovative concept whereby complex NASA space power electronic systems can be configured using a small number of qualified hybrid DC-DC converter and...

  19. Development of a DC-DC conversion powering scheme for the CMS Phase-1 pixel upgrade

    CERN Document Server

    Feld, Lutz Werner; Karpinski, Waclaw; Klein, Katja; Lipinski, Martin; Preuten, Marius; Max Rauch; Rittich, David Michael; Sammet, Jan Domenik; Wlochal, Michael

    2014-01-01

    A novel powering scheme based on the DC-DC conversion technique will be exploited to power the CMS Phase-1 pixel detector. DC-DC buck converters for the CMS pixel project have been developed, based on the AMIS5 ASIC designed by CERN. The powering system of the Phase-1 pixel detector is described and the performance of the converter prototypes is detailed, including power efficiency, stability of the output voltage, shielding, and thermal management. Results from a test of the magnetic field tolerance of the DC-DC converters are reported. System tests with pixel modules using many components of the future pixel barrel system are summarized. Finally first impressions from a pre-series of 200 DC-DC converters are presented.

  20. DIAGNOSTIC/PROGNOSTIC EXPERIMENTS FOR CAPACITOR DEGRADATION AND HEALTH MONITORING IN DC-DC CONVERTERS

    Data.gov (United States)

    National Aeronautics and Space Administration — Studying and analyzing the ageing mechanisms of electronic components avionics in systems such as the GPS and INAV are of critical importance. In DC-DC power...

  1. Digitally intensive DC-DC converter for extreme space environments, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The Space Micro –Arizona State University (ASU) team will develop an all-digitally controlled, wide temperature range point-of-load switch-mode DC-DC regulator core...

  2. Digitally intensive DC-DC converter for extreme space environments, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The Space Micro-Arizona State University (ASU) team will develop an all-digitally controlled, wide temperature range point-of-load switch-mode DC-DC regulator core...

  3. 75 FR 61352 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-30, DC-10-30F, DC-10-30F (KC...

    Science.gov (United States)

    2010-10-05

    ... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 10-30, DC-10-30F, DC-10-30F (KC-10A and KDC-10...-13 McDonnell Douglas Corporation: Amendment 39-16448; Docket No. FAA-2010-0553; Directorate.... Applicability (c) This AD applies to McDonnell Douglas Corporation Model DC- 10-30, DC-10-30F, DC-10-30F (KC-10A...

  4. 75 FR 27401 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-9-30, DC-9-40, and DC-9-50...

    Science.gov (United States)

    2010-05-17

    ... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 9-30, DC-9-40, and DC-9-50 Series Airplanes... airworthiness directive (AD) for certain Model DC-9-30, DC-9-40, and DC-9-50 series airplanes. This AD requires... this AD to detect and correct the potential for an arc/spark condition to occur within the fuel boost...

  5. Response of tobacco to the Pseudomonas syringae pv. Tomato DC3000 is mainly dependent on salicylic acid signaling pathway.

    Science.gov (United States)

    Liu, Yang; Wang, Li; Cai, Guohua; Jiang, Shanshan; Sun, Liping; Li, Dequan

    2013-07-01

    Pseudomonas syringae pv. Tomato DC3000 (Pst DC3000) was the first pathogen to be demonstrated to infect Arabidopsis and to cause disease symptoms in the laboratory setting. However, the defense response to Pst DC3000 was unclear in tobacco. In this report, the expression profiles of twelve defense response-related genes were analyzed after treatment with salicylic acid (SA), jasmonic acid (JA), and pathogen Pst DC3000 by qRT-PCR. According to our results, it could be presented that the genes primarily induced by SA were also induced to higher levels after Pst DC3000 infection. SA accumulation could be induced to a higher level than that of JA after Pst DC3000 infection. In addition, SA could result in hypersensitive response (HR), which did not completely depend on accumulation of reactive oxygen species. These results indicated that tobacco mainly depended on SA signaling pathway rather than on JA signaling pathway in response to Pst DC3000. Further study demonstrated that JA could significantly inhibit the accumulation of SA and the generation of the HR induced by Pst DC3000. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  6. Reactive Kripke semantics

    CERN Document Server

    Gabbay, Dov M

    2013-01-01

    This text offers an extension to the traditional Kripke semantics for non-classical logics by adding the notion of reactivity. Reactive Kripke models change their accessibility relation as we progress in the evaluation process of formulas in the model. This feature makes the reactive Kripke semantics strictly stronger and more applicable than the traditional one. Here we investigate the properties and axiomatisations of this new and most effective semantics, and we offer a wide landscape of applications of the idea of reactivity. Applied topics include reactive automata, reactive grammars, rea

  7. Novel composite resonance DC-DC converter with voltage doubler rectifier

    OpenAIRE

    Kato, Hisatsugu; Matsuo, Hirohumi; Eguchi, Masaki; Sakamoto, Yukitaka; Nakaishi, Masaki

    2009-01-01

    This paper deals with a novel composite resonance DC-DC converter with the voltage doubler rectifier, which is developed to be applied to the power conditioner of the photovoltaic generation system. The proposed DC-DC converter has the current and voltage resonance functions. Therefore, the output voltage regulation can be achieved for the large variations of the input voltage and load. Also, this converter has the high power efficiency. The maximum power efficiency 96.1% can be realized.

  8. Regulation of DC development and DC-mediated T-cell immunity via CISH

    OpenAIRE

    Miah, Mohammad Alam; Bae, Yong-Soo

    2013-01-01

    Cytokine inducible SH2-containing protein (CISH) plays a crucial role in type 1 dendritic cell (DC) development as well as in the DC-mediated activation of cytotoxic T lymphocytes (CTLs). CISH expression at late DC developmental stages shuts down the proliferation of DC progenitors by negatively regulating signal transducer and activator of transcription 5 (STAT5) and facilitates the differentiation of DCs into potent stimulators of CTLs.

  9. Regulation of DC development and DC-mediated T-cell immunity via CISH.

    Science.gov (United States)

    Miah, Mohammad Alam; Bae, Yong-Soo

    2013-03-01

    Cytokine inducible SH2-containing protein (CISH) plays a crucial role in type 1 dendritic cell (DC) development as well as in the DC-mediated activation of cytotoxic T lymphocytes (CTLs). CISH expression at late DC developmental stages shuts down the proliferation of DC progenitors by negatively regulating signal transducer and activator of transcription 5 (STAT5) and facilitates the differentiation of DCs into potent stimulators of CTLs.

  10. Design and Analysis of Two-Phase Boost DC-DC Converter

    OpenAIRE

    Taufik Taufik; Tadeus Gunawan; Dale Dolan; Makbul Anwari

    2010-01-01

    Multiphasing of dc-dc converters has been known to give technical and economical benefits to low voltage high power buck regulator modules. A major advantage of multiphasing dc-dc converters is the improvement of input and output performances in the buck converter. From this aspect, a potential use would be in renewable energy where power quality plays an important factor. This paper presents the design of a 2-phase 200W boost converter for battery charging application. Analysis of results fr...

  11. A Fixed-Frequency Bidirectional Resonant DC-DC Converter Suitable for Wide Voltage Gain Range

    DEFF Research Database (Denmark)

    Shen, Yanfeng; Wang, Huai; Blaabjerg, Frede

    2017-01-01

    This paper proposes a new bidirectional resonant dc-dc converter suitable for wide voltage gain range applications (e.g., energy storage systems). The proposed converter overcomes the narrow voltage gain range of conventional resonant DC-DC converters, and meanwhile achieves high efficiency...... and characteristics of the proposed converter are analyzed. Finally, a 1-kW converter prototype is built and the experimental results verify the theoretical analyses....

  12. Development of a green mode DC/DC converter available to portable nuclear instrument

    International Nuclear Information System (INIS)

    Gao Feiyan; Wu Longxiong; Tan Wei; Tang Yaogeng

    2010-01-01

    A green mode DC/DC converter was developed which suitable to the portable nuclear instrument which is powered by battery and is sometime at stand-by mode. Some updated control approaches such as pseudo-resonant type power supply control and synchronous rectification were adopted to makethe DC/DC converter operate with low power consumption and high efficiency. The test results the battery can be prolonged with this converter. (authors)

  13. Superconducting dc fault current limiter

    International Nuclear Information System (INIS)

    Cointe, Y.

    2007-12-01

    Within the framework of the electric power market liberalization, DC networks have many interests compared to alternative ones, but their protections need to use new systems. Superconducting fault current limiters enable by an overstepping of the critical current to limit the fault current to a preset value, lower than the theoretical short-circuit current. For these applications, coated conductors offer excellent opportunities. We worked on the implementation of these materials and built a test bench. We carried out limiting experiments to estimate the quench homogeneity at various short-circuit parameters. An important point is the temperature measurement by deposited sensors on the ribbon, results are in good correlation with the theoretical models. Improved quench behaviours for temperatures close to the critical temperature have been confirmed. Our results enable to better understand the limitation mechanisms of coated conductors. (author)

  14. The possibility of detecting DC

    International Nuclear Information System (INIS)

    Witte, N.S.; Brown, R.D.

    1977-01-01

    IRC + 10216, a bright infrared late type carbon star, is observed to have millimetre range line emission of the species 12 CO, 13 CO, CS, C 2 H, HC 3 N, CN, HCN, SiS and SiO in an extended envelope around the central infrared sources. A model explaining the line emission in terms of infrared pumping between the two lowest vibrational levels, first proposed for IRC + 10216, was used to calculate antenna temperatures for various rotational transitions of HC 3 N; since there is a prima facie agreement between the calculated and observed values for HC 3 N we have attempted the same calculation for DC 3 N. (J.R.)

  15. Lentivirus-Induced Dendritic Cells (iDC for Immune-Regenerative Therapies in Cancer and Stem Cell Transplantation

    Directory of Open Access Journals (Sweden)

    Renata Stripecke

    2014-08-01

    Full Text Available Conventional dendritic cells (cDC are ex vivo differentiated professional antigen presenting cells capable of potently stimulating naïve T cells and with vast potential for immunotherapeutic applications. The manufacture of clinical-grade cDC is relatively complex and requires several days for completion. Clinical trials showed poor trafficking of cDC from subcutaneous injection sites to lymph nodes (LN, where DC can optimally stimulate naïve lymphocytes for long-lasting memory responses. We demonstrated in mouse and human systems that a single overnight ex vivo lentiviral (LV gene transfer into DC precursors for production of combination of cytokines and antigens was capable to induce autonomous self-differentiation of antigen-loaded DC in vitro and in vivo. These highly viable induced DC (iDC effectively migrated from the injected skin to LN, where they effectively activated de novo antigen-specific effector memory T cells. Two iDC modalities were validated in relevant animal models and are now in clinical development: Self-differentiated Myeloid-derived Antigen-presenting-cells Reactive against Tumors co-expressing GM-CSF/IL-4/TRP2 for melanoma immunotherapy in the autologous setting (SmartDCtrp2, and Self-differentiated Myeloid-derived Lentivirus-induced against human cytomegalovirus as an allogeneic matched adoptive cell after stem cell transplantation (SmyleDCpp65. The lentiviral vector design and packaging methodology has “evolved” continuously in order to simplify and optimize function and biosafety of in vitro and in vivo genetic reprogramming of iDC. Here, we address the challenges seeking for new creations of genetically programmed iDC and integrase-defective LV vaccines for immune regeneration.

  16. Power supply and pulsing strategies for the future linear colliders

    International Nuclear Information System (INIS)

    Brogna, A S; Weber, M; Göttlicher, P

    2012-01-01

    The concept of the power delivery systems of the future linear colliders exploits the pulsed bunch structure of the beam in order to minimize the average current in the cables and the electronics and thus to reduce the material budget and heat dissipation. Although modern integrated circuit technologies are already available to design a low-power system, the concepts on how to pulse the front-end electronics and further reduce the power are not yet well understood. We propose a possible implementation of a power pulsing system based on a DC/DC converter and we choose the Analog Hadron Calorimeter as a specific example. The model features large switching currents of electronic modules in short time intervals to stimulate the inductive components along the cables and interconnections.

  17. Superconducting energy stabilizer with charging and discharging DC-DC converters

    International Nuclear Information System (INIS)

    Kim, S.H.; Kostecki, E.L.; DeWinkel, C.C.

    1992-01-01

    This patent describes a superconducting energy stabilizer having multiple load connections and employing DC-DC conversion for storing energy in a superconducting inductive energy storage device having a first end and a second end, and for releasing the stored energy from the superconducting inductive energy storage device to a load or loads or to a utility or an industrial electrical distribution system, the superconducting energy stabilizer having multiple load connections and employing DC-DC conversion. It comprises: energy storage cell means for supplying energy to the load, discharging DC-DC converter means for releasing energy from the superconducting inductive energy storage device to the energy storage cell means, the discharging DC-DC converter means having input terminals, output terminals, and a discharging control line means for carrying signals controlling the operation of the discharging DC-DC converter means, one of the input terminals of the discharging DC-DC converter means coupled to the first end of the superconducting energy storage device

  18. Effect of reactive and un-reactive substrates on photopolymerization of self-etching adhesives with different aggressiveness.

    Science.gov (United States)

    Zhang, Ying; Wang, Yong

    2013-01-01

    The study investigated the influence of reactive (enamel) and un-reactive (glass) substrates on photo-polymerization of self-etching adhesives. Two commercial adhesives Adper Prompt L-Pop (APLP, pH~0.8) and Adper Easy Bond (AEB, pH~2.5) were applied onto prepared enamel and glass substrates using the same protocol. Micro-Raman spectroscopy was employed to determine the degree of conversion (DC) and the involved mechanism. DC of APLP was dramatically enhanced from ~9.4% to ~82.0% as when changing from glass to enamel, while DC of AEB on both substrates showed no difference. The DC distributions along the adhesive layers of the APLP and AEB on enamel showed descending and constant trends, respectively. Spectral analysis disclosed that the difference in chemical reaction of the two adhesives with enamel might be associated with the results. The chemical reaction of the adhesives with enamel significantly improved the DC of the strong APLP, but not that of the mild AEB.

  19. Reactive sputter deposition of boron nitride

    International Nuclear Information System (INIS)

    Jankowski, A.F.; Hayes, J.P.; McKernan, M.A.; Makowiecki, D.M.

    1995-10-01

    The preparation of fully dense, boron targets for use in planar magnetron sources has lead to the synthesis of Boron Nitride (BN) films by reactive rf sputtering. The deposition parameters of gas pressure, flow and composition are varied along with substrate temperature and applied bias. The films are characterized for composition using Auger electron spectroscopy, for chemical bonding using Raman spectroscopy and for crystalline structure using transmission electron microscopy. The deposition conditions are established which lead to the growth of crystalline BN phases. In particular, the growth of an adherent cubic BN coating requires 400--500 C substrate heating and an applied -300 V dc bias

  20. Research on Digital Output Verification Technology of Electronic DC Current Transformer

    Science.gov (United States)

    Chen, Yuanjie; Wang, Bin; Hu, Haoliang; Xiong, Qianzhu; Yang, Chunyan

    2017-05-01

    Aiming at the error of calibration system when conducting field calibration by electronic DC current transformer’s digital calibration system, an electronic DC current transformer’s digital calibration system based on protocol conversion is proposed and researched. Data frames outputted from merging unit are collected and converted by the system, the digital synchronization is realized by using the synchronous clock device to trigger the second pulse, and it is verified by the virtual instrument design software. The field calibration is conducted to some converter station digital dc current transformer under the rated current of 500A by using the calibration system. By calibrating and analyzing errors, the error is less than 0.075% when tested current is more than 40% of the rated current. According the standard in literature[1], performance of the calibration system is perfect, measured results perfectly meet the requirements of design, and the calibration system has great practical application value.

  1. Adaptive Sliding-Mode Control in Bus Voltage for an Islanded DC Microgrid

    Directory of Open Access Journals (Sweden)

    Dan Zhang

    2017-01-01

    Full Text Available The control of bus voltage is a crucial task for the stable operation of islanded DC microgrids. To improve the DC bus voltage control dynamics and stability, this paper proposes an adaptive sliding-mode control method based on large-signal model. The sliding-mode control, adaptive observation, and fix-frequency pulse width modulation technology are adopted and combined efficiently, which guarantee stable bus voltage and the constant switching frequency of closed-loop system, regardless of how the parameters vary with the variable constant-power loads and uncertainties. In addition, the reference values can be quickly tracked by the state variables using the proposed method without any additional sensors/hardware circuits. Therefore, this method is beneficial for the scalability and plug-play of the distributed generators and loads within the DC microgrids. The performance of the proposed control method has been successfully verified in simulation.

  2. A measurement method for determination of dc internal resistance of batteries and supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Shuhong; Wu, Feng [Department of Materials Science, Beijing Science and Technology University, Beijing 100081 (China); Yang, Liuxiang; Gao, Lijun [Department of Chemistry, NanChang University, JiangXi 330031 (China); Burke, Andrew F. [Institute of Transportation, University of California, Davis, CA 95616 (United States)

    2010-02-15

    Internal resistance is an importance parameter determining the power performance of a battery or supercapacitor. An 8.5 Ah Li-ion battery and a 350 F supercapacitor were tested as examples to validate the measurement method of dc internal resistance. Voltage data were taken at 10 ms, 2 s and 30 s after the current interruption or pulse. The ac resistances at 1 kHz of the battery and supercapacitor were also measured for comparison with the dc values. Based on these tests, it is proposed that the dc internal resistance of the battery and supercapacitor be obtained from {delta}V/{delta}I where the {delta}V is the voltage change after the current interruption, and {delta}I means current change from I to 0. When the voltage change at 10 ms or less is selected, the resistance corresponds to the Ohmic resistance of the device. (author)

  3. DC Langmuir Probe for Measurement of Space Plasma: A Brief Review

    Directory of Open Access Journals (Sweden)

    Koichiro Oyama

    2015-09-01

    Full Text Available Herein, we discuss the in situ measurement of the electron temperature in the ionosphere/plasmasphere by means of DC Langmuir probes. Major instruments which have been reported are a conventional DC Langmuir probe, whose probe voltage is swept; a pulsed probe, which uses pulsed bias voltage; a rectification probe, which uses sinusoidal signal; and a resonance cone probe, which uses radio wave propagation. The content reviews past observations made with the instruments above. We also discuss technical factors that should be taken into account for reliable measurement, such as problems related to the contamination of electrodes and the satellite surface. Finally, we discuss research topics to be studied in the near future.

  4. The experimental study of digital reactivity meter with space effect elimination

    International Nuclear Information System (INIS)

    Xie, Y.Q.; Jian, Z.B.; Zhang, Y.S.

    1988-01-01

    The paper summarizes a digital reactivity measurement theory with space effect elimination. On the basis of the theory, we have prepared an on-line digital reactivity meter with space effect elimination. This system is composed of neutron detector and magnifying, data acquisition channel, monoplate microprocessor and data output channel. Measured results of reactivity using the method described in this paper are in agreement with measured results of reactivity using the pulsed neutron method and 'ρ-shape' method within experimental error. (author)

  5. Reactive perforating collagenosis

    Directory of Open Access Journals (Sweden)

    Yadav Mukesh

    2009-01-01

    Full Text Available Reactive perforating collagenosis is a rare cutaneous disorder of unknown etiology. We hereby describe a case of acquired reactive perforating collagenosis in a patient of diabetes and chronic renal failure.

  6. Dual wound dc brush motor gearhead

    Science.gov (United States)

    Henson, Barrie W.

    1986-01-01

    The design requirements, the design, development tests and problems, the qualification and life test and the findings of the strip examination of a dual wound DC brushed motor gearhead are described. It is the only space qualified dual wound dc brushed motor gearhead in Europe.

  7. Electronic DC transformer with high power density

    NARCIS (Netherlands)

    Pavlovský, M.

    2006-01-01

    This thesis is concerned with the possibilities of increasing the power density of high-power dc-dc converters with galvanic isolation. Three cornerstones for reaching high power densities are identified as: size reduction of passive components, reduction of losses particularly in active components

  8. DC/DC converters for integration of double-layer condensers in onboard power supply; DC/DC-Wandler zur Einbindung von Doppelschichtkondensatoren in das Fahrzeugenergiebordnetz

    Energy Technology Data Exchange (ETDEWEB)

    Polenov, Dieter

    2010-01-15

    The paper discusses DC/DC converters for integration of double layer condensers into the onboard power system. First, requirements on DC/DC converters are listed and compared on the basis of three exemplary applications. A DC/DC converter concept is developed for decoupling transient high-power loads like electric steering systems. Three different topologies are compared using a specially developed method in order to find the best solution for the given application. In order to establish adequate criteria for selecting the switching frequency and inductivities of storage throttles, the influence of the trottle power change on the switching characteristics of the MOSFETs and on certain ranges of EMP interference emissions is investigated. As methods of optimising the operation of the synchronous rectifiers, parallel connection of Schottky diodes and synchronous rectifiers as well as the variation of the shut-off dead times of synchronous rectifiers were investigated. Further, a concept for converter control was developed in consideration of the intended application and topology. Finally, selected aspects for implementation of the DC/DC converter concept are presented as well as the results of experimental investigations.

  9. Modelling of flow phenomena during DC casting

    NARCIS (Netherlands)

    Zuidema, J.

    2005-01-01

    Modelling of Flow Phenomena during DC Casting Jan Zuidema The production of aluminium ingots, by semi-continuous casting, is a complex process. DC Casting stands for direct chill casting. During this process liquid aluminium transforms to solid aluminium while cooling down. This is not an

  10. DC KIDS COUNT e-Databook Indicators

    Science.gov (United States)

    DC Action for Children, 2012

    2012-01-01

    This report presents indicators that are included in DC Action for Children's 2012 KIDS COUNT e-databook, their definitions and sources and the rationale for their selection. The indicators for DC KIDS COUNT represent a mix of traditional KIDS COUNT indicators of child well-being, such as the number of children living in poverty, and indicators of…

  11. A 70 MHz pulsing beam system for protons

    International Nuclear Information System (INIS)

    An Shizhong; Zhang Tianjue; Wu Longcheng; Lv Yinlong; Song Guofang; Guan Fengping; Jia Xianlu

    2008-01-01

    A test beam line for pulsed beam generation for 10 MeV central region model (CRM) of a compact cyclotron is under construction as China Institute of Atomic Energy (CIAE). A 70 MHz continuous H - beam with the energy of dozens of keV or a hundred keV will be pulsed to pulse length of less than 10 ns with the repetition rate of 1-8 MHz. A 70.487 MHz buncher will be used to compress the DC beam into the RF phase acceptance of ±30° of the CRM cyclotron. The 2.2 MHz sine waveform will be used for the chopper. A pulse with the repetition rate to 4.4 MHz and pulse length less than 10 ns is expected after CRM cyclotron. (authors)

  12. Coordinating Flexibility under Uncertainty in Multi-Area AC and DC Grids

    DEFF Research Database (Denmark)

    Halilbasic, Lejla; Chatzivasileiadis, Spyros; Pinson, Pierre

    2017-01-01

    In the future, mixed AC and DC grids, spanning multiple areas operated by different transmission system operators (TSO), are expected to offer the necessary controllability for integrating large amounts of intermittent renewable generation. This is facilitated by high voltage direct current...... transmission based on voltage source converter technology that can offer recourse actions in the form of preventive and corrective control of both active and reactive power. Market-clearing procedures, based on optimal power flow algorithms, need to be revised to account for DC transmission, flexibility...... and privacy requirements. To this end, we propose a decentralized two-stage stochastic market-clearing algorithm that incorporates meshed DC grids and allows the sharing of flexibility resources between areas. The benefit of this approach lies in its pricing mechanism, used for coordinating the different area...

  13. Decentralised control method for DC microgrids with improved current sharing accuracy

    DEFF Research Database (Denmark)

    Yang, Jie; Jin, Xinmin; Wu, Xuezhi

    2017-01-01

    A decentralised control method that deals with current sharing issues in dc microgrids (MGs) is proposed in this study. The proposed method is formulated in terms of ‘modified global indicator’ concept, which was originally proposed to improve reactive power sharing in ac MGs. In this work......, the ‘modified global indicator’ concept is extended to coordinate dc MGs, which aims to preserve the main features offered by decentralised control methods such as no need of communication links, central controller or knowledge of the microgrid topology and parameters. This global indicator is inserted between...... a shunt virtual resistance. The operation under multiple dc-buses is also included in order to enhance the applicability of the proposed controller. A detailed mathematical model including the effect of network mismatches is derived for analysis of the stability of the proposed controller. The feasibility...

  14. Autonomous Operation of Hybrid Microgrid with AC and DC Sub-Grids

    DEFF Research Database (Denmark)

    Loh, Poh Chiang; Blaabjerg, Frede

    2011-01-01

    the power flow among all the sources distributed throughout the two types of sub-grids, which certainly is tougher than previous efforts developed for only either ac or dc microgrid. This wider scope of control has not yet been investigated, and would certainly rely on the coordinated operation of dc...... sources, ac sources and interlinking converters. Suitable control and normalization schemes are therefore developed for controlling them with results presented for showing the overall performance of the hybrid microgrid.......This paper investigates on the active and reactive power sharing of an autonomous hybrid microgrid. Unlike existing microgrids which are purely ac, the hybrid microgrid studied here comprises dc and ac sub-grids, interconnected by power electronic interfaces. The main challenge here is to manage...

  15. Using variable DC sources in order to improve the voltage quality of a multilevel STATCOM with low frequency modulation

    DEFF Research Database (Denmark)

    Dowlatabadi, Mohammadkazem Bakhshizadeh; Najjar, Mohammad; Blaabjerg, Frede

    2016-01-01

    In this paper, a Selective Harmonic Elimination Pulse Width Modulation (SHE-PWM) method, which utilizes adjustable dc links, is presented for a Static Synchronous Compensator (STATCOM) based on Cascaded H-Bridge (CHB) multilevel converter. The proposed switching algorithm is able to fix the capac......In this paper, a Selective Harmonic Elimination Pulse Width Modulation (SHE-PWM) method, which utilizes adjustable dc links, is presented for a Static Synchronous Compensator (STATCOM) based on Cascaded H-Bridge (CHB) multilevel converter. The proposed switching algorithm is able to fix...... unequal dc link voltages more levels at the output is achievable compared to the symmetrical multilevel converters that could be used in enhancing the power quality, while keeping the switching frequency near the fundamental (the maximum switching frequency can be kept below 150 Hz). The validity...

  16. Detailed design of a 13 kA 13 kV dc solid-state turn-off switch

    International Nuclear Information System (INIS)

    Praeg, W.F.

    1985-01-01

    An experimental facility for the study of electromagnetic effects in the First Wall-Blanket-shield (FWBS) systems of fusion reactors has been constructed at Argonne National Laboratory (ANL). In a test volume of 0.76 m 3 , a vertical, pulsed 5 kG dipole field (B -1 ) is perpendicular to a 10 kG solenoid field. Power supplies of 2.75 MW at 550 V dc and 5.5 MW at 550 V dc and a solid-state switch rated at 13 kA and 13 kV (169 MW) control the pulsed magnetic fields. The total stored energy in the coils is 2.6 MJ. This paper describes the design and construction features of the solid-state switching circuit which turns off a dc of 13 kA in approximately 82 μs and holds off voltages of < 13 kV

  17. Reactivity on the Web

    OpenAIRE

    Bailey, James; Bry, François; Eckert, Michael; Patrânjan, Paula Lavinia

    2005-01-01

    Reactivity, the ability to detect simple and composite events and respond in a timely manner, is an essential requirement in many present-day information systems. With the emergence of new, dynamic Web applications, reactivity on the Web is receiving increasing attention. Reactive Web-based systems need to detect and react not only to simple events but also to complex, real-life situations. This paper introduces XChange, a language for programming reactive behaviour on the Web,...

  18. Random pulse generator

    International Nuclear Information System (INIS)

    Guo Ya'nan; Jin Dapeng; Zhao Dixin; Liu Zhen'an; Qiao Qiao; Chinese Academy of Sciences, Beijing

    2007-01-01

    Due to the randomness of radioactive decay and nuclear reaction, the signals from detectors are random in time. But normal pulse generator generates periodical pulses. To measure the performances of nuclear electronic devices under random inputs, a random generator is necessary. Types of random pulse generator are reviewed, 2 digital random pulse generators are introduced. (authors)

  19. Semiconductor laser diodes and the design of a D.C. powered laser diode drive unit

    OpenAIRE

    Cappuccio, Joseph C., Jr.

    1988-01-01

    Approved for public release; distribution is unlimited This thesis addresses the design, development and operational analysis of a D.C. powered semiconductor laser diode drive unit. A laser diode requires an extremely stable power supply since a picosecond spike of current or power supply switching transient could result in permanent damage. The design offers stability and various features for operational protection of the laser diode. The ability to intensity modulate (analog) and pulse m...

  20. Monadic Functional Reactive Programming

    NARCIS (Netherlands)

    A.J. van der Ploeg (Atze); C Shan

    2013-01-01

    htmlabstractFunctional Reactive Programming (FRP) is a way to program reactive systems in functional style, eliminating many of the problems that arise from imperative techniques. In this paper, we present an alternative FRP formulation that is based on the notion of a reactive computation: a

  1. A Component-Reduced Zero-Voltage Switching Three-Level DC-DC Converter

    DEFF Research Database (Denmark)

    Qin, Zian; Pang, Ying; Wang, Huai

    2016-01-01

    The basic Zero-Voltage Switching (ZVS) three-level DC-DC converter has one clamping capacitor to realize the ZVS of the switches, and two clamping diodes to clamp the voltage of the clamping capacitor. In order to reduce the reverse recovery loss of the diode as well as its cost, this paper...... proposes to remove one of the clamping diodes in basic ZVS three-level DC-DC converter. With less components, the proposed converter can still have a stable clamping capacitor voltage, which is clamped at half of the dc link voltage. Moreover, the ZVS performance will be influenced by removing the clamping...

  2. Improved Control Strategy for T-type Isolated DC/DC Converters

    DEFF Research Database (Denmark)

    Liu, Dong; Deng, Fujin; Wang, Yanbo

    2017-01-01

    T-type isolated DC/DC converters have recently attracted attention due to their numerous advantages, including few components, low cost, and symmetrical operation of transformers. This study proposes an improved control strategy for increasing the efficiency of T-type isolated DC/DC converters....... Under the proposed strategy, the primary circulating current flows through the auxiliary switches (metal–oxide–semiconductor field-effect transistors) instead of their body diodes in free-wheeling periods. Such feature can reduce conduction losses, thereby improving the efficiency of T-type isolated DC...

  3. DC Voltage Droop Control Implementation in the AC/DC Power Flow Algorithm: Combinational Approach

    DEFF Research Database (Denmark)

    Akhter, F.; Macpherson, D.E.; Harrison, G.P.

    2015-01-01

    of operational flexibility, as more than one VSC station controls the DC link voltage of the MTDC system. This model enables the study of the effects of DC droop control on the power flows of the combined AC/DC system for steady state studies after VSC station outages or transient conditions without needing...... to use its complete dynamic model. Further, the proposed approach can be extended to include multiple AC and DC grids for combined AC/DC power flow analysis. The algorithm is implemented by modifying the MATPOWER based MATACDC program and the results shows that the algorithm works efficiently....

  4. Design of PI Controlled Non Isolated Bidirectional DC to DC Converter for Electric Vehicle Application

    Science.gov (United States)

    Geetha, A.; Subramani, C.; Thamizh Thentral, T. M.; Krithika, V.; Usha, S.

    2018-04-01

    Non isolated Bidirectional DC-DC Converter (NIBDDC) is a good interface between DC source and inverter Fed induction motor drive. This paper deals with comparison between open loop and PI controlled Bidirectional DC to DC Converter Inverter System (BDDCIS). The modelling and control of BDDC is becomes an important issue. Open loop BDDCIS and closed loop PI controlled BDDCIS are designed, modelled and simulated using Matlab- simulink and their results are presented. The investigations indicate superior performance of PI controlled BDDCIS. The proposed BDDCIS has advantages like bidirectional power transfer ability, reduced hardware count and improved dynamic response.

  5. Influence of reactive gas admixture on transition metal cluster nucleation in a gas aggregation cluster source

    Science.gov (United States)

    Peter, Tilo; Polonskyi, Oleksandr; Gojdka, Björn; Mohammad Ahadi, Amir; Strunskus, Thomas; Zaporojtchenko, Vladimir; Biederman, Hynek; Faupel, Franz

    2012-12-01

    We quantitatively assessed the influence of reactive gases on the formation processes of transition metal clusters in a gas aggregation cluster source. A cluster source based on a 2 in. magnetron is used to study the production rate of titanium and cobalt clusters. Argon served as working gas for the DC magnetron discharge, and a small amount of reactive gas (oxygen and nitrogen) is added to promote reactive cluster formation. We found that the cluster production rate depends strongly on the reactive gas concentration for very small amounts of reactive gas (less than 0.1% of total working gas), and no cluster formation takes place in the absence of reactive species. The influence of discharge power, reactive gas concentration, and working gas pressure are investigated using a quartz micro balance in a time resolved manner. The strong influence of reactive gas is explained by a more efficient formation of nucleation seeds for metal-oxide or nitride than for pure metal.

  6. Programmable pulse generator

    International Nuclear Information System (INIS)

    Xue Zhihua; Lou Binqiao; Duan Xiaohui

    2002-01-01

    The author introduces the design of programmable pulse generator that is based on a micro-controller and controlled by RS232 interface of personal computer. The whole system has good stability. The pulse generator can produce TTL pulse and analog pulse. The pulse frequency can be selected by EPLD. The voltage amplitude and pulse width of analog pulse can be adjusted by analog switches and digitally-controlled potentiometers. The software development tools of computer is National Instruments LabView5.1. The front panel of this virtual instrumentation is intuitive and easy-to-use. Parameters can be selected and changed conveniently by knob and slide

  7. An improved power control strategy for hybrid AC-DC microgrids

    DEFF Research Database (Denmark)

    Baharizadeh, Mehdi; Karshenas, Hamid Reza; Guerrero, Josep M.

    2018-01-01

    This paper presents a new droop-based control strategy for hybrid microgrids (HMG) with improved power sharing. When ac microgrids (AC-MG) and dc microgrids (DC-MG) are present in a distribution grid, there is an opportunity to interconnect them via an interlinking converter (IC) and form a HMG......, the possibility of participation of IC in AC-MG reactive power adds some complexity to a HMG control system. In this paper, a new decentralized control strategy is presented for a HMG which relies on regulating the voltage magnitude of a common bus in each microgrid. In this regard, new droop characteristics...... for sources across both microgrids as well as IC are proposed. The proposed droop characteristics result in better active/reactive power sharing across both microgrids and at the same time results in better voltage regulation. The derivation of new droop characteristics is thoroughly discussed in this paper...

  8. Drilling history core hole DC-4

    International Nuclear Information System (INIS)

    1978-12-01

    Core hole DC-4 was completed at a depth of 3998 feet in December, 1978 by Boyles Brothers Drilling Company, Spokane, Washington, under subcontract to Fenix and Scission, Inc. The hole was cored for the US Department of Energy and the Rockwell Hanford Operations' Basalt Waste Isolation Program. Fenix and Sicsson, Inc. furnished the engineering, daily supervision of the cable tool and core drilling activities, and geological core logging for DC-4. Core hole DC-4 is located on the Hanford Site about 3 miles east of the Yakima Barricade and approximately 103 feet southwest of rotary hole DC-5, which was completed to 3990 feet in February, 1978. Hanford Site coordinates reported for hole DC-4 are north 49,385.62 feet and west 85,207.63 feet, and Washington State coordinates are north 454,468.73 feet and east 2,209,990.87 feet. No elevation survey is available for hole DC-4, but it is approximately 745 feet above mean sea level based upon the survey of hole DC-5, which has a reported elevation of 745.16 feet on the top of the 3-inch flange. The purpose of core hole DC-4 was to core drill vertically through the basalt and interbed units for stratigraphic depth determination and core collection, and to provide a borehole for hydrologic testing, cross-hole seismic shear, and pressure wave velocity studies with rotary hole DC-5. Hole DC-4 was drilled through the overburden into basalt bedrock by cable tool methods (0-623 feet) and continuously cored through the final interval (623 to 3998 feet).Core recovery was 95.8 percent of the total footage cored

  9. A Dual-Buck–Boost AC/DC Converter for DC Nanogrid With Three Terminal Outputs

    DEFF Research Database (Denmark)

    Wu, Weimin; Wang, Houqing; Liu, Yuan

    2017-01-01

    Due to the widely used dc characterized loads and more distributed power generation sources, the dc nanogrid becomes more and more popular, and it is seen as an alternative to the ac grid. For safety considerations, the dc nanogrid should provide reliable grounding for the residential loads...... such as the low-voltage ac power system. There are three typical grounding configurations for a dc nanogrid: the united grounding, the unidirectional grounding, and the virtual isolated grounding. Each grounding configuration has its own specifications to ac/dc converters. In this paper, a dual-buck-boost ac/dc...... converter for use in the united-grounding-configuration-based dc nanogrid with three terminal outputs is proposed. The working principle of this converter is presented in detail through analyzing the equivalent circuits. Experiments are carried out to verify the theoretical analysis....

  10. A high voltage ratio and low ripple interleaved DC-DC converter for fuel cell applications.

    Science.gov (United States)

    Chang, Long-Yi; Chao, Kuei-Hsiang; Chang, Tsang-Chih

    2012-01-01

    This paper proposes a high voltage ratio and low ripple interleaved boost DC-DC converter, which can be used to reduce the output voltage ripple. This converter transfers the low DC voltage of fuel cell to high DC voltage in DC link. The structure of the converter is parallel with two voltage-doubler boost converters by interleaving their output voltages to reduce the voltage ripple ratio. Besides, it can lower the current stress for the switches and inductors in the system. First, the PSIM software was used to establish a proton exchange membrane fuel cell and a converter circuit model. The simulated and measured results of the fuel cell output characteristic curve are made to verify the correctness of the established simulation model. In addition, some experimental results are made to validate the effectiveness in improving output voltage ripple of the proposed high voltage ratio interleaved boost DC-DC converters.

  11. Engineering Design of the ITER AC/DC Power Supplies

    International Nuclear Information System (INIS)

    Oh, B. H.; Lee, K. W.; Hwang, C. K.; Jin, J. T.; Chang, D. S.; Kim, T. S.

    2009-02-01

    To design high power pulse power supplies, especially in huge power supplies have not designed till now, it is necessary to analyze a system's characteristics and relations with another systems as well as to know high voltage, high current control technologies. Contents of this project are; - Study for the engineering designs changed recently by ITER Organization(IO) and writing specifications for the power supplies to reduce project risk. - Detailed analysis of the AC/DC Converters and writing subtask reports on the Task Agreement. - Study for thyristor numbers, DCR's specifications for Korea-China sharing meetings. - Study for the grounding systems of the ITER power supply system. The results may used as one of reference for practical designs of the high power coil power supplies and also may used in various field such as electroplating, plasma arc furnaces, electric furnaces

  12. Digital reactivity meter

    International Nuclear Information System (INIS)

    Akkus, B.; Anac, H.; Alsan, S.; Erk, S.

    1991-01-01

    Nowadays, various digital methods making use of microcomputers for neutron detector signals and determining the reactivity by numerical calculations are used in reactor control systems in place of classical reactivity meters. In this work, a calculation based on the ''The Time Dependent Transport Equation'' has been developed for determining the reactivity numerically. The reactivity values have been obtained utilizing a computer-based data acquisition and control system and compared with the analog reactivity meter values as well as the values calculated from the ''Inhour Equation''

  13. Method of controlling reactivity

    International Nuclear Information System (INIS)

    Tochihara, Hiroshi.

    1982-01-01

    Purpose: To improve the reactivity controlling characteristics by artificially controlling the leakage of neutron from a reactor and providing a controller for controlling the reactivity. Method: A reactor core is divided into several water gaps to increase the leakage of neutron, its reactivity is reduced, a gas-filled control rod or a fuel assembly is inserted into the gap as required, the entire core is coupled in a system to reduce the leakage of the neutron, and the reactivity is increased. The reactor shutdown is conducted by the conventional control rod, and to maintain critical state, boron density varying system is used together. Futher, a control rod drive is used with that similar to the conventional one, thereby enabling fast reactivity variation, and the positive reactivity can be obtained by the insertion, thereby improving the reactivity controlling characteristics. (Yoshihara, H.)

  14. Pulsed water jet generated by pulse multiplication

    Czech Academy of Sciences Publication Activity Database

    Dvorský, R.; Sitek, Libor; Sochor, T.

    2016-01-01

    Roč. 23, č. 4 (2016), s. 959-967 ISSN 1330-3651 R&D Projects: GA MŠk(CZ) LO1406; GA MŠk ED2.1.00/03.0082 Institutional support: RVO:68145535 Keywords : high- pressure pulses * pulse intensifier * pulsed water jet * water hammer effect Subject RIV: JQ - Machines ; Tools Impact factor: 0.723, year: 2016 http://hrcak.srce.hr/163752?lang=en

  15. Improved DC Gun Insulator Assembly

    International Nuclear Information System (INIS)

    Neubauer, M.L.; Dudas, A.; Sah, R.; Poelker, M.; Surles-Law, K.E.L.

    2010-01-01

    Many user facilities such as synchrotron radiation light sources and free electron lasers require accelerating structures that support electric fields of 10-100 MV/m, especially at the start of the accelerator chain where ceramic insulators are used for very high gradient DC guns. These insulators are difficult to manufacture, require long commissioning times, and often exhibit poor reliability. Two technical approaches to solving this problem will be investigated. Firstly, inverted ceramics offer solutions for reduced gradients between the electrodes and ground. An inverted design will be presented for 350 kV, with maximum gradients in the range of 5-10 MV/m. Secondly, novel ceramic manufacturing processes will be studied, in order to protect triple junction locations from emission, by applying a coating with a bulk resistivity. The processes for creating this coating will be optimized to provide protection as well as be used to coat a ceramic with an appropriate gradient in bulk resistivity from the vacuum side to the air side of an HV standoff ceramic cylinder. Example insulator designs are being computer modelled, and insulator samples are being manufactured and tested

  16. Investigations of dc breakdown fields

    CERN Document Server

    Ramsvik, Trond; Reginelli, Alessandra; Taborelli, Mauro

    2006-01-01

    The need for high accelerating gradients for the future 30 GHz multi-TeV e+e- Compact Linear Collider (CLIC) at CERN has triggered a comprehensive study of DC breakdown fields of metals in UHV. The study shows that molybdenum (Mo), tungsten (W), titanium (Ti) and TiVAl reach high breakdown fields, and are thus good candidates for the iris material of CLIC structures. A significant decrease in the saturated breakdown field (Esat) is observed for molybdenum and tungsten when exposed to air. Specifically, at air pressures of 10-5 mbar, the decrease in Esat is found to be 50% and 30% for molybdenum and tungsten, respectively. In addition, a 30% decrease is found when molybdenum is conditioned with a CO pressure of ~1-10-5 mbar. Surface analysis measurements and breakdown conditioning in O2 ambience imply that the origin of the decrease in Esat is closely linked to oxide formation on the cathode surface. "Ex-situ" treatments by ion bombardment of molybdenum effectively reduce the oxide layers, and improve the brea...

  17. A THREE-PHASE BOOST DC-AC CONVERTER

    African Journals Online (AJOL)

    dc-ac converter (inverter) based on the dc-dc boost converters. ... Sliding mode controllers are designed to perform a robust control for the ... Computer simulations and spectral analysis demon- ... the conventional three-phase buck inverter,.

  18. 75 FR 75872 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-9-30, DC-9-40, and DC-9-50...

    Science.gov (United States)

    2010-12-07

    ... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 9-30, DC-9-40, and DC-9-50 Series Airplanes...: We are adopting a new airworthiness directive (AD) for the McDonnell Douglas Corporation airplanes... to include an airworthiness directive (AD) that would apply to certain McDonnell Douglas Model DC-9...

  19. A modular approach for RFX D.C. power supplies

    International Nuclear Information System (INIS)

    Bolognani, S.; Ciscato, D.; Tenti, P.

    1981-01-01

    A modular approach to the realization of D.C. Power Supplies of the Reverse Field Pinch Experiment (RFX) is presented. A basic convertor module configuration is proposed which enables a high flexibility of the power supply system to be obtained, as required to cope with the plasma behaviour uncertainties. The basic convertor module rating has been selected to meet all the expected load requirements and a preliminary design of the convertor has been carried out for evaluating the technical and economical feasibility of the system. Different fault conditions have been analyzed and protective devices have been devised accordingly. Finally simulated profiles of the active and reactive power drawn from the AC mains are reported. (author)

  20. Improvement of the dynamic response of the ITER Reactive Power Compensation system

    International Nuclear Information System (INIS)

    Finotti, Claudio; Gaio, Elena; Song, Inho; Tao, Jun; Benfatto, Ivone

    2015-01-01

    Highlights: • The slow response reasons of the classic ITER Reactive Power Compensation (RPC) control are explained. • The dynamic behaviors of the ac/dc converter and of the RPC are characterized. • New control concept to speed up the RPC response is developed. • Good performance of the new RPC control is verified even during fast transient conditions. - Abstract: The ITER ac/dc conversion system can absorb a total active and reactive power up to 500 MW and 950 Mvar, respectively. The Reactive Power Compensation (RPC) system is rated for a nominal power of 750 Mvar necessary to comply with the allowable reactive power limit value from the grid of 200 Mvar. This system is currently under construction and is based on Static Var Compensation technology with Thyristor Controlled Reactor (TCR) and Tuned Filters. The RPC has to minimize the demand of reactive power from the grid; its control is based on a feed-forward method, where the corrective input is the measurement of the reactive power consumption of the ac/dc converters, derived from the 50 Hz component of the Fast Fourier Transform (FFT) of the three-phase voltages and currents. The delay introduced by the FFT calculation and the slow response of the TCR could make the response speed of the RPC not sufficient to face fast variations of the reactive power demand and therefore in this paper a new controller of the RPC able to overcome this shortcoming is proposed and evaluated. It is based on the calculation of the predicted consumption of the reactive power by using the voltage reference signals coming from the Plasma Control System and the measurements of the dc current of the ac/dc converters and of the 66 kV busbar voltage, and on the speed up of the RPC control by introducing a lead–lag transfer function.