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1

Electrical breakdown of gases  

Microsoft Academic Search

A collection of individual works on electrical discharges is presented. Topics covered include: fundamental processes in the electrical breakdown of gases; vacuum breakdown; spark breakdown in uniform fields; corona discharge; spark breakdown in non-uniform fields; breakdown voltage characteristics; irradiation and time lags; high-frequency breakdown of gases; laser-induced electrical breakdown of gases; spark channels; and electrode phenomena. (GHT)

J. M. Meek; J. D. Craggs

1978-01-01

2

Surface Breakdown Characteristics of Silicone Oil for Electric Power Apparatus  

NASA Astrophysics Data System (ADS)

This paper describes the surface breakdown characteristics of the silicone oil which has the possibility of the application to innovative switchgear as an insulating medium. At the first step, we have experimentally studied on the impulse breakdown characteristics of the configuration with a triple-junction where a solid insulator is in contact with the electrode. The test configurations consist of solid material (Nomex and pressboard) and liquid insulation oil (silicone and mineral oil). We have discussed the experimental results based on the maximal electric field at a triple-junction. As the second step, we have studied the configuration which may improve the surface breakdown characteristics by lowering the electric field near the triple-junction.

Wada, Junichi; Nakajima, Akitoshi; Miyahara, Hideyuki; Takuma, Tadasu; Okabe, Shigemitu; Kohtoh, Masanori; Yanabu, Satoru

3

Electrical breakdown characteristic of nanostructured W?Cu contacts materials  

Microsoft Academic Search

Nanostructured (NS) W?Cu composite powder was prepared by mechanical alloying (MA), and nanostructured bulk of W?Cu contact\\u000a material was fabricated by hot press sintering in an electrical vacuum furnace. The microstructure, electric conductivity,\\u000a hardness and break down voltage of NS W?Cu alloys were measured and compared to those of conventional W?Cu alloys prepared\\u000a by powder metallurgy. The experimental results show

Wang Junbo; Chen Wen'ge; Ding Binjun

2006-01-01

4

Breakdown Characteristics of an Isolated Conducting Object in a Uniform Electric Field.  

National Technical Information Service (NTIS)

A laboratory experiment was conducted to determine the physical processes involved in the electrical breakdown of a particular spark gap arrangement. The gap consists of an isolated conducting ellipsoid located midway between two large flat electrodes. Gr...

M. G. Grothaus T. F. Trost

1986-01-01

5

Vacuum Electrical Breakdown Characteristics of Oxygen-free Copper Electrodes Processed by Precision Machining in Clean Space  

NASA Astrophysics Data System (ADS)

The vacuum electrical breakdown characteristics of oxygen-free copper electrodes, which were processed by precision diamond turning machining in a clean room and were heat-treated in hydrogen after that machining, were investigated by applying impulse voltage. These electrodes were carried in mobile vacuum chamber in order to keep them clean. The surface conditions were analyzed by the X-ray Photoelectron Spectroscopy (XPS) before and after the ion-beam sputtering and after the 500 times repetitive breakdowns. These experiments can be performed in in-situ experimental apparatus that are maintained in ultra-high vacuum (10-7 to 10-8Pa). As a result, these electrodes showed higher breakdown fields at the first breakdown relative to values obtained in the past studies. In addition, their conditioning achieved with less number of breakdowns. According to the XPS spectra, it was confirmed that organic contaminants were reduced by heat treatment in hydrogen and ion beam sputtering. These shows that heat treatment in hydrogen is effective in reducing contaminants on the electrode surface and improving the breakdown characteristics.

Yamamoto, Takashi; Otsuka, Takahiro; Yamano, Yasushi; Kobayashi, Shinichi; Higo, Toshiyasu; Toge, Nobukazu; Takata, Koji; Higashi, Yasuo; Saito, Yoshio; Hitomi, Nobuteru

6

Characteristics of edge breakdowns on Teflon samples  

NASA Technical Reports Server (NTRS)

The characteristics of electrical discharges induced on silverbacked Teflon samples irradiated by a monoenergetic electron beam have been studied under controlled laboratory conditions. Measurements of breakdown threshold voltages indicate a marked anisotropy in the electrical breakdown properties of Teflon: differences of up to 10 kV in breakdown threshold voltage are observed depending on the sample orientation. The material anisotropy can be utilized in spacecraft construction to reduce the magnitude of discharge currents.

Yadlowsky, E. J.; Hazelton, R. C.; Churchill, R. J.

1980-01-01

7

Influence of the hot filament on the electrical breakdown characteristics in the presence of Ar/N2  

NASA Astrophysics Data System (ADS)

The influence of a hot filament on the electrical breakdown characteristics is studied for different ratios of argon and nitrogen gases for a wide range of pressure. The vacuum tube consists of two parallel plane stainless steels used as cathode and anode accompanied with a tungsten filament located behind the cathode. Paschen's curves are obtained for different ratios of argon and nitrogen as a function of pressure for various electric currents of the hot filament. The first and second Townsend coefficients as well as the ionization efficiency and secondary ionization coefficient are obtained for different filament currents. In addition, the influences of the nitrogen partial pressure on the forgoing parameters are obtained. It is shown that, increase of the filament current causes the decrease of the electrical breakdown voltage which is more pronounced in low pressures. Furthermore, introducing the nitrogen gas leads to the increase of the breakdown voltage and decrease of the ionization efficiency as well as the first and second Townsend coefficients. Moreover, it is concluded that, in the middle range of pressure, the presence of the hot filament results to the electrical breakdown which reveals the linear features.

Borkhari, Arian Fateh; Yasserian, Kiomars

2013-01-01

8

Breakdown characteristics of an isolated conducting object in a uniform electric field  

NASA Technical Reports Server (NTRS)

A laboratory experiment was conducted to determine the physical processes involved in the electrical breakdown of a particular spark gap arrangement. The gap consists of an isolated conducting ellipsoid located midway between two large flat electrodes. Gradual increase of the applied electric field, E, in the gap produces corona on the ellipsoid tips followed by flashover in a leader-arc sequence. The leader phase consists of the abrupt formation of ionized channels which partially bridge the gap and then decay prior to the arc. Measurements of dE/dt and of current were made, and photographs were taken with an image converter. Experimental parameters are listed.

Grothaus, M. G.; Trost, T. F.

1986-01-01

9

Electrical breakdown characteristic of a Ce-doped W-Cu contact material  

Microsoft Academic Search

W-Cu composite powder doped with Ce (1.5 wt.%) was prepared by mechanical alloying (MA), and the W-Cu contact material was\\u000a fabricated by hot pressing sintering in an electrical vacuum furnace. The microstructure, electric conductivity, hardness,\\u000a and breakdown voltage of the Ce-doped W-Cu alloy were measured and compared with a conventional W-Cu alloy prepared by powder\\u000a metallurgy. The results show that

Kewen Hu; Mianzhi Chen; Heng Ye

2010-01-01

10

Vacuum Electrical Breakdown Characteristics of Oxygen-free Copper Electrodes Processed by Precision Machining in Clean Space  

Microsoft Academic Search

The vacuum electrical breakdown characteristics of oxygen-free copper electrodes, which were processed by precision diamond turning machining in a clean room and were heat-treated in hydrogen after that machining, were investigated by applying impulse voltage. These electrodes were carried in mobile vacuum chamber in order to keep them clean. The surface conditions were analyzed by the X-ray Photoelectron Spectroscopy (XPS)

Takashi Yamamoto; Takahiro Otsuka; Yasushi Yamano; Shinichi Kobayashi; Toshiyasu Higo; Nobukazu Toge; Koji Takata; Yasuo Higashi; Yoshio Saito; Nobuteru Hitomi

2003-01-01

11

Breakdown Characteristics of Electrical Discharges in High-Density Helium Near the Critical Point  

NASA Astrophysics Data System (ADS)

We present an investigation of the breakdown behavior of micrometer gap direct-current discharges in gaseous, supercritical, and liquid helium, which shows a critical anomaly of the breakdown voltage near the critical point. A discharge model that combines gas- and liquid-like breakdown mechanisms and takes into account the local fluid structure in a fluctuating fluid with the concept of a modified electron mean free path, allows us to reproduce the breakdown behavior. The result of the analysis suggests that the critical breakdown anomaly is caused by long acceleration paths inside low-density domains resulting from the density fluctuation.

Muneoka, Hitoshi; Urabe, Keiichiro; Stauss, Sven; Terashima, Kazuo

2013-08-01

12

D.c. breakdown voltage characteristics in supercritical helium: breakdown in nonuniform fields  

Microsoft Academic Search

This Paper describes the results of an experimental study on the d.c. breakdown voltage characteristic of supercritical helium under a non-uniform electric field. The study was carried out to further the development of superconducting magnets cooled by supercritical helium. At a certain density value, varrhoc, a maximum breakdown voltage is observed in the breakdown voltage versus density characteristic. In the

S. Nakayama; D. Ito

1986-01-01

13

Electrical Breakdown Characteristics of Superconducting Magnet System in Sub-Cooled Liquid Nitrogen  

Microsoft Academic Search

Dielectric characteristics of gaseous helium (GHe) injected into the cooling system to make sub-cooled nitrogen condition with constant pressure is found to be extraordinarily weak in dielectric strength by H. Mitsuii (1998). In high voltage superconducting machines using the sub-cooled nitrogen cooling system, the current lead part in GHe environment could be electrical weak points rather than the superconducting magnet

Hyoungku Kang; Chanjoo Lee; Tae Kuk Ko; Bok-Yeol Seok

2007-01-01

14

Evaluation of Breakdown Characteristics of Gas Insulated Switchgears for Non-standard Lightning Impulse Waveforms - Breakdown Characteristics for Double-frequency Oscillations under Non-uniform Electric Field  

Microsoft Academic Search

An effective means of rationalization of insulation design for gas insulated switchgear (GIS) is the evaluation of insulation characteristics under actual surge waveforms in the field called non-standard lightning impulse waveforms (non-standard-LIWs). The preceding researches examined quasi-uniform electric field SF6 gas gaps and partly the cone-shaped insulating spacers that represent an insulation element of GIS in order to obtain the

Genyo Ueta; Shuhei Kaneko; Shigemitsu Okabe

2009-01-01

15

Breakdown characteristics of xenon HID Lamps  

NASA Astrophysics Data System (ADS)

The breakdown characteristics of mercury free xenon high intensity discharge (HID) lamps exhibit a large statistical time lag often having a large scatter in breakdown voltages. In this paper, we report on results from a computational investigation of the processes which determine the ignition voltages for positive and negative pulses in commercial HID lamps having fill pressures of up to 20 atm. Steep voltage rise results in higher avalanche electron densities and earlier breakdown times. Circuit characteristics also play a role. Large ballast resistors may limit current to the degree that breakdown is quenched. The breakdown voltage critically depends on cathode charge injection by electric field emission (or other mechanisms) which in large part controls the statistical time lag for breakdown. For symmetric lamps, ionization waves (IWs) simultaneously develop from the bottom and top electrodes. Breakdown typically occurs when the top and bottom IWs converge. Condensed salt layers having small conductivities on the inner walls of HID lamps and on the electrodes can influence the ignition behavior. With these layers, IWs tend to propagate along the inner wall and exhibit a different structure depending on the polarity.

Babaeva, Natalia; Sato, Ayumu; Brates, Nanu; Noro, Koji; Kushner, Mark

2009-10-01

16

Electrical and Electroluminescence Characteristics of AlGaN/GaN High Electron Mobility Transistors Operated in Sustainable Breakdown Conditions  

NASA Astrophysics Data System (ADS)

This paper reports on an extensive analysis of the electrical and optical properties of GaN-based high electron mobility transistors (HEMTs) biased in a non-destructive breakdown regime. By means of a number of measurements carried out with varying voltage and temperature conditions, we show that: (i) HEMTs can reach a sustainable breakdown condition, when they are biased in current-controlled mode, with a gate voltage smaller than the pinch-off voltage; (ii) when biased in sustainable breakdown, HEMTs can emit a weak luminescence signal, localized in proximity of the drain edge; (iii) the breakdown voltage (BDV) is strongly dependent on temperature. Through a careful investigation of the drain, source and gate current components, we demonstrate that breakdown originates from two different mechanisms, depending on the gate voltage: for gate voltages close to the pinch-off, breakdown current originates from the space charge injection of electrons from the source to the drain. On the other hand, for more negative gate voltages, breakdown current originates from the injection of electrons from the gate. Finally, the analysis of the temperature dependence of the breakdown current confirms that two different mechanisms significantly contribute to current conduction at high drain voltage levels.

Meneghini, Matteo; Zanandrea, Alberto; Rampazzo, Fabiana; Stocco, Antonio; Bertin, Marco; Cibin, Giulia; Pogany, Dionyz; Zanoni, Enrico; Meneghesso, Gaudenzio

2013-08-01

17

Evaluation of breakdown characteristics of gas insulated switchgears for non-standard lightning impulse waveforms - breakdown characteristics under non-uniform electric field  

Microsoft Academic Search

To lower the lightning impulse withstand voltage of gas insulated switchgear (GIS) while maintaining the high reliability of its insulation performance, it is important to define in an organized way the insulation characteristics for non-standard lightning impulse voltage waveforms that represent actual surge waveforms in the field and compare them with the characteristics for the standard lightning impulse waveform quantitatively.

Genyo Ueta; Shuhei Kaneko; Shigemitsu Okabe

2008-01-01

18

Electrical breakdown of anodic aluminum oxide  

Microsoft Academic Search

Results are presented from a study of electrical breakdown of anodic aluminum oxide in a constant field with a platinum pressure electrode. Statistical breakdown parameters and their dependence on the magnitude and polarity of the applied voltage are obtained. Field and temperature dependences of breakdown delay time t over the interval 10-6–103 sec are determined. It is shown that the

V. A. Laléko; N. Yu. Ershova

1990-01-01

19

Electrical breakdown of anodic aluminum oxide  

Microsoft Academic Search

Results are presented from a study of electrical breakdown of anodic aluminum oxide in a constant field with a platinum pressure electrode. Statistical breakdown parameters and their dependence on the magnitude and polarity of the applied voltage are obtained. Field and temperature dependences of breakdown delay time tau over the interval 10-6 103 sec are determined. It is shown that

V. A. Laléko; N. Yu. Ershova

1990-01-01

20

Electrical Breakdown of Submillimeter Water Gaps  

Microsoft Academic Search

Electrical breakdown and recovery processes in water have been studied using electrical and nanosecond optical diagnostics. The breakdown electric field in submillimeter gaps with 200 ns voltage pulses applied has been measured as 1 MV\\/cm, the rate of current rise during breakdown reaches 4.1011 A\\/s. The switch recovery time is determined by expansion and decay of a vapor bubble. The

K. H. Schoenbach; J. Cooper; A. Garner; B. Goan; R. P. Joshi; J. Kolb; S. Katsuki; S. Kono; M. Laroussi; F. Leipold; X. Lu; C. Mallot; J. Quian; S. Xiao

2002-01-01

21

Electrical breakdown of water in microgaps  

NASA Astrophysics Data System (ADS)

Experimental and modeling studies on electrical breakdown in water in submillimeter gaps between pin and plane electrodes have been performed. Prebreakdown, breakdown and recovery of the water gaps were studied experimentally by using optical and electrical diagnostics with a temporal resolution on the order of one nanosecond. By using Mach-Zehnder interferometry, the electric field distribution in the prebreakdown phase was determined by means of the Kerr effect. Electric fields values in excess of the computed electric fields, which reach >4 MV cm-1 for applied electrical pulses of 20 ns duration, were recorded at the tip of the pin electrode, an effect which can be explained by a reduced permittivity of water at high electric fields. Breakdown of the gaps, streamer-to-arc transition, was recorded by means of high-speed electrical diagnostics, and through high-speed photography. It was shown, through simulations, that breakdown is initiated by field emission at the interface of preexisting microbubbles. Impact ionization within the micro-bubble's gas then contributes to plasma development. Experiments using pulse-probe methods and Schlieren diagnostics allowed us to follow the development of the disturbance caused by the breakdown over a time of more than milliseconds and to determine the recovery time of a water switch. In order to trigger water switches a trigger electrode with a triple point has been utilized. The results of this research have found application in the construction of compact pulse power generators for bioelectric applications.

Schoenbach, Karl; Kolb, Juergen; Xiao, Shu; Katsuki, Sunao; Minamitani, Yasushi; Joshi, Ravindra

2008-05-01

22

Electrical breakdown and space charge of polyphenylene sulfide films  

Microsoft Academic Search

The electrical breakdown of PPS (polyphenylene sulfide) films of three different thicknesses was investigated. Impulse breakdown strength was almost constant in the temperature range from -60 to 150°C, but showed a negative thickness dependence, suggesting electron avalanche breakdown. Assuming single electron avalanche breakdown, the mean free path was estimated to be about 9 Å. The DC breakdown strength was lower

T. Mizutani; M. Hikita; A. Umemura; M. Ieda

1989-01-01

23

Flashover and breakdown characteristics in low pressure environments  

Microsoft Academic Search

A present trend in aircraft design is the increasing use of 270-Vdc power circuitry. Also, significant voltage spikes may be superimposed on the dc level. In many situations involving unsealed equipment enclosures, electrical insulation is provided by a combination of gaseous medium and spacing between conductors. Consequently, flashover\\/breakdown characteristics of electrical wiring and printed-circuit-board traces depend upon the environment in

Dennis Grosjean; Donald Kasten; Stephen Sebo; Titus Chen; Michael Rupp; Daniel Schweickart

2011-01-01

24

Electrical Breakdown at Solid-Liquid Interfaces  

Microsoft Academic Search

Observations of the electrohydrodynamic (EHD) motion of insulating oils in a static electric field, between plane parallel electrodes separated by an insulating support, are reported. A transition from laminar to turbulent flow in the bridged gap is observed near breakdown voltages. Velocity measurements support the observations of the onset of turbulent flow prior to flashoever while photographic observations show the

Edward Cherney; James Cross

1977-01-01

25

Origin of thickness dependent dc electrical breakdown in dielectrics  

NASA Astrophysics Data System (ADS)

A model based on space charge dynamics under high dc electric field has been proposed to explain commonly observed thickness dependent breakdown of polymeric material. The formation and dynamics of space charge will result in local electric field enhancement that has a direct impact on dielectric breakdown. The simulation results show that the breakdown depends on the sample thickness with a power index of 0.143, indicating the space charge and its dynamics are responsible for thickness dependent breakdown. The model also predicts the effect of voltage ramping rate on the electrical breakdown strength.

Chen, George; Zhao, Junwei; Li, Shengtao; Zhong, Lisheng

2012-05-01

26

Evaluation of breakdown characteristics of gas insulated switchgears for non-standard lightning impulse waveforms - breakdown characteristics in the presence of bias voltages under non-uniform electric field  

Microsoft Academic Search

To lower the lightning impulse withstand voltage of gas insulated switchgear (GIS) while maintaining the high reliability of its insulation performance, it is important to define in an organized way the insulation characteristics for non-standard lightning impulse voltage waveforms that represent actual surge waveforms in the field and compare them with the characteristics for the standard lightning impulse waveform quantitatively.

Genyo Ueta; Shuhei Kaneko; Shigemitsu Okabe

2009-01-01

27

AC breakdown characteristics of epoxy nanocomposites  

Microsoft Academic Search

Experiments were conducted to measure the ac breakdown strength of epoxy alumina nanocomposites with different filler loadings of 0.1, 1 and 5 wt%. The experiments were performed as per the ASTM D 149 standard on samples of thickness 0.5 mm, 1 mm and 3 mm in order to study the effect of thickness on the ac breakdown strength of epoxy

P. Preetha; M. Joy Thomas

2011-01-01

28

Breakdown characteristics of metal halide plasma lamps  

Microsoft Academic Search

Nowadays, metal halide plasma lamps are compact and efficient light sources. The dynamics of their breakdown stage are of actual research interest for improving reliable lamp ignition at comparatively low voltages. In order to study the influence of additives on the lamps' breakdown phase at high pressure, a simplified lamp geometry was used, containing 5 bar Xenon and some milligrams

S. Peters; M. Kettlitz; M. Wendt; A. Moss

2008-01-01

29

Evaluation of breakdown characteristics of CO2 gas for non-standard lightning impulse waveforms under non-uniform electric field - breakdown characteristics for single-frequency oscillation waveforms -  

Microsoft Academic Search

SF6 gas, an insulation medium used for gas insulated switchgear (GIS), has a high global warming potential, hence an effective alternative means is expected from the environmental perspective. As one of its potential alternatives, the authors are focusing on CO2 gas, which has relatively good insulation characteristics among gases with a low environmental impact (natural gases). To use this CO2

Junichi Wada; Genyo Ueta; Shigemitsu Okabe

2011-01-01

30

AC breakdown characteristics of epoxy alumina nanocomposites  

Microsoft Academic Search

Experiments were conducted to measure the ac breakdown strength of 0.5 mm, thick epoxy alumina nanocomposites with different filler concentrations of 0.1, 1 and 5wt%. The experiments were performed as per the ASTM D 149 standard. It was observed that the ac breakdown strength was marginally lower up to 1wt% filler concentration and then increased at 5wt% filler concentration as

P. Preetha; M. Joy Thomas

2010-01-01

31

Electrical Conduction and Breakdown in Liquid Dielectrics  

Microsoft Academic Search

Measurements of the breakdown strength of purified organic liquids have been made using rectangular voltage pulses of duration between 0.2 and 20 microseconds. The effects of cathode metal, ?-radiation and of changes in pulse duration, electrode separation, temperature, constitution of the liquid, etc. lead to a theory of breakdown according to which an instability arises as a result of electron

D W Goodwin; K A Macfadyen

1953-01-01

32

Electrical Breakdown in a Martian Gas Mixture  

NASA Technical Reports Server (NTRS)

The high probability for dust interactions during Martian dust storms and dust devils combined with the cold, dry climate of Mars most likely result in airborne dust that is highly charged. On Earth, potential gradients up to 5 kV/m have been recorded and in some cases resulted in lightning. Although the Martian atmosphere is not conducive to lightning generation, it is widely believed that electrical discharge in the form of a corona occurs. In order to understand the breakdown of gases, Paschen measurements are taken which relate the minimum potential required to spark across a gap between two electrodes. The minimum potential is plotted versus the pressure-distance value for electrodes of a given geometry. For most gases, the potential decreases as the pressure decreases. For CO2, the minimum in the curve happens to be at Mars atmospheric pressures (5-7 mm Hg) for many distances and geometries. However, a very small amount (<0.1%) of mixing gases radically changes the curve, as noted by Leach. Here, we present the first experimental results of a Paschen curve for a Mars gas mixture compared with 100% pure CO2.

Buhler, C. R.; Calle, C. I.; Nelson, E.

2003-01-01

33

Electrical breakdown in thin oxides during bias-temperature ramps  

SciTech Connect

Electrical breakdown in thin oxides is assessed by a new bias-temperature ramp technique. No significant effect of radiation exposure on breakdown is observed for high quality thermal and nitrided oxides, up to 20 Mrad(SiO{sub 2}).

FLEETWOOD,D.M.; RIEWE,LEONARD CHARLES; WINOKUR,PETER S.; SEXTON,FREDERICK W.

2000-02-08

34

Study on the lightning impulse breakdown characteristics of gaseous insulation media for the design of a high voltage superconducting apparatus  

NASA Astrophysics Data System (ADS)

In general, the current leads of high voltage superconducting apparatuses cooled by liquid nitrogen are exposed to gaseous insulation media. Therefore, the investigation on the electrical breakdown characteristics of gaseous insulation media should be performed to develop electrically reliable high voltage superconducting power apparatuses. In this study, the lightning impulse breakdown tests on gaseous insulation media are conducted by using sphere-to-plane electrode systems made of stainless steel. Also, the lightning impulse breakdown voltage tests on gaseous insulation media according to various pressures are performed. The experimental results show that the electrical breakdown characteristics under lightning impulse voltage are affected by the gap length between electrode systems, the size of electrodes, and the field utilization factors. From these results, the electrical insulation design criteria to estimate the electrical breakdown voltage are established. The results are expected to be applicable to the design of current leads for high voltage superconducting apparatuses.

Kang, H.; Na, J. B.; Ahn, M. C.; Bae, D. K.; Kim, Y. H.; Ko, T. K.

2010-11-01

35

Plancktons in a unified theory of electrical breakdown  

Microsoft Academic Search

Over a decade ago, a theory based on Paschen's law was proposed to unify electrical breakdown in gaseous, liquid, and solid dielectrics. In liquids, the mechanism proposed was the growth of vapor bubbles by the electrical heating accompanying electron avalanche. However, if submicroscopic bubbles pre-exist in liquid dielectrics before the electric field is applied, the formation of vapor bubbles would

T. V. Prevenslik

1999-01-01

36

Breakdown characteristics and conditioning of carbon and refractory metal electrodes  

NASA Technical Reports Server (NTRS)

High voltage carbon and refractory metal electrodes employed in devices used in space, such as ion thrusters and traveling wave tubes, can be easily damaged by electrical breakdown and arcing events. Modification of the electrode surfaces due to these events can impact the voltage hold off capability of the surfaces, which could lead to additional arcing, further damage, and the potential for device failure. On the cathode-potential surface, the arc energy is deposited by all of the processes at the surface ultimately responsible for net electron emission, such as melting, vapor and particulate formation, sputtering, ion bombardment, etc. On the anode-potential surface, the energy is deposited from the plasma or electron stream that crosses the gap, which causes surface damage by local heating. In spite of this energy dependence on the damage, many systems that use arc discharges characterize the amount of material removed from the surfaces and the lifetime of the device for voltage hold-off by the amount of current that passes through the arc, or the 'Coulomb-rating'. The results of a series of tests that were preformed on the boltage hold off capability and damage to carbon-carbon composite surfaces and molybdenum surfaces due to induced arcing will be presented and discussed. Damage to the surfaces was characterized by the field emission performance after the arc initiation and SEM photographs for the different energy and coulomb-transfer arc conditions. Both conditioning and damage to the surfaces were observed, and will be related to the characteristics of the electrical breakdown.

Goebel, Dan M.

2004-01-01

37

The effect of contaminant in breakdown time lag of uniform electric field using impulse breakdown in mineral oil  

Microsoft Academic Search

A breakdown time lag of uniform electric field using sphere-sphere electrodes was measured in pure mineral oil and in contaminated oil. The electrodes were steel spheres of diameter 12.5 mm. The effect for breakdown time lag wielded by differences of the distance between electrodes, applied impulse voltage and contaminant was measured, The breakdown time lag increased proportionally to applied voltage

H. Naoshi; O. A. Aloys; A. Kiyomitsu

1999-01-01

38

Breakdown Characteristics Study on an 18 Cell X-band Structure  

SciTech Connect

A CLIC designed 18 cells, low group velocity (2.4% to 1.0% c), X-band (11.4 GHz) accelerator structure (denoted T18) was designed at CERN, its cells were built at KEK, and it was assembled and tested at SLAC. An interesting feature of this structure is that the gradient in the last cell is about 50% higher than that in the first cell. This structure has been RF conditioned at SLAC NLCTA for about 1400 hours where it incurred about 2200 breakdowns. This paper presents the characteristics of these breakdowns, including (1) the breakdown rate dependence on gradient, pulse width and conditioning time, (2) the breakdown distribution along the structure, (3) relation between breakdown and pulsed heating dependence study and (4) electric field decay time for breakdown changing over the whole conditioning time. Overall, this structure performed very well, having a final breakdown rate of less than 1e-6/pulse/m at 106 MV/m with 230 ns pulse width.

Wang, Faya; ,

2008-11-12

39

Electrode area of breakdown depending on conditioning mechanism under non-uniform electric field in vacuum  

Microsoft Academic Search

In this paper, we discussed the breakdown (BD) area of electrode on conditioning characteristics under non-uniform electric field in vacuum. Negative standard lightning impulse voltage was applied between rod and plane electrodes made of Cu-Cr and stainless steel for different tip radii and gap lengths. Experimental results revealed how the electrode area of BD and the BD field strength depend

Hitoshi Okubo; F. Miyazaki; Y. Inagawa; K. Kato; M. Sakaki; H. Ichikawa

2004-01-01

40

Electrical breakdown of Space Station Freedom surfaces  

NASA Technical Reports Server (NTRS)

Space Station Freedom (SSF) will be the largest and highest power spacecraft that the U.S. has put into orbit. The solar array will generate 160 volts nominal when in sunlight, and the present baseline design is for the negative end of the solar array to be tied to SSF structure. Due to the balance of leakage currents through the plasma, the structure will be driven approximately 140 volts negative of the ambient conductive ionospheric plasma. Surface materials such as anodized aluminum will have this voltage drop across a thin dielectric which may not have sufficient dielectric strength to prevent dielectric breakdown. This can lead to arcing on the exterior surfaces of Space Station.

Carruth, M. R., Jr.; Vaughn, J. A.; Bechtel, R. T.; Gray, P. A.

1992-01-01

41

Reducing bubbles in glass coatings improves electrical breakdown strength  

NASA Technical Reports Server (NTRS)

Helium reduces bubbles in glass coatings of accelerator grids for ion thrustors. Fusing the coating in a helium atmosphere creates helium bubbles in the glass. In an argon atmosphere, entrapped helium diffuses out of the glass and the bubbles collapse. The resultant coating has a substantially enhanced electrical breakdown strength.

Banks, B.

1968-01-01

42

Analysis of the electrical breakdown in hydrogenated amorphous silicon thin-film transistors  

Microsoft Academic Search

Electrical breakdown induced by systematic electrostatic discharge (ESD) stress of thin-film transistors used as switches in active matrix addressed liquid crystal displays has been studied using electrical measurements, electrical simulations, electrothermal simulations, and postbreakdown observations. Breakdown due to very short pulses (up to 1 ?s) shows a clear dependence on the channel length. A hypothesis that electrical breakdown in the

Natasa Tosic Golo; Fred G. Kuper; Ton J. Mouthaan

2002-01-01

43

Plasma formation and electrical breakdown in water  

Microsoft Academic Search

Summary form only given. The temporal development of plasma formation in water with up to MV\\/cm pulsed electric fields applied was explored in a strongly inhomogeneous (wire-plane), and a semi-homogeneous (sphere-plane) electric field configuration. In the first case, by applying 120 kV voltage pulses to a tungsten wire with a diameter of 75 pm, and the second, plane electrode being

S. Katsuki; F. Leipold; M. Laroussi; K. H. Schoenbach

2002-01-01

44

Electrical breakdown of sub-millimeter water gaps  

Microsoft Academic Search

We have studied the temporal development of the electrical breakdown in water by means of electrical and optical diagnostic methods. Distilled water with a resistivity of 200 k?cm was placed between a 1.7 mm diameter sphere steel electrode and a plane stainless steel electrode. The gap distance was varied from 50 ?m to 400 ?m. Up to 50 kV high

S. Katsuki; S. Xiao; R. P. Joshi; M. Laroussi; K. H. Schoenbach; J. Kolb; S. Kono; F. Leipold; X. Lu; C. Mallot; J. Quian

2002-01-01

45

Resistance of a pulsed electrical breakdown channel in ionic crystals  

NASA Astrophysics Data System (ADS)

A technique for estimating the resistance of the electrical breakdown channel in ionic crystals is proposed. This technique is based on measuring the channel velocity in a sample when a ballast resistor is connected to the circuit of a needle anode and on using the theoretical dependence of the channel velocity on the channel conductivity. The breakdown channel resistance at a voltage of 140 kV is about 6.5 k? in KCl and about 6.1 k? in KBr. These resistances are shown to characterize a gas phase. The gas-phase resistance is found to be nonuniform along the breakdown channel. The head part ˜1 mm long has the maximum resistance. This head region is concluded to contain dielectric substance clusters, which then decompose into metal and halogen ions. The cluster lifetime is ˜10-9 s.

Punanov, I. F.; Emlin, R. V.; Kulikov, V. D.; Cholakh, S. O.

2014-04-01

46

Impulse-Breakdown Characteristics of Polymers Immersed in Insulating Oil  

Microsoft Academic Search

Surface discharges along oil-immersed solids used as insulators and supports in high-voltage pulsed-power equipment can lead to catastrophic system failures. To achieve reliable compact pulsed-power systems, it is important to quantify the electrical fields at which surface flashover, or other types of breakdown event, will occur for different dielectric materials. This paper reports the observed behavior of samples of polypropylene,

Mark P. Wilson; Martin J. Given; Igor V. Timoshkin; Scott J. MacGregor; Mark A. Sinclair; Kenneth J. Thomas; Jane M. Lehr

2010-01-01

47

Impulse breakdown characteristics of dielectric materials immersed in insulating oil  

Microsoft Academic Search

Surface discharges along oil-immersed solids chosen to insulate high-voltage, pulsed-power systems are a problem that can lead to catastrophic failure. Knowledge of the electrical fields at which surface flashover, or other types of breakdown event, will occur for different dielectric materials is therefore important for the proper design of insulating components for pulsed-power systems. In the present work, impulse voltages

M. P. Wilson; S. J. MacGregor; I. V. Timoshkin; M. J. Given; M. A. Sinclair; K. J. Thomas; J. M. Lehr

2009-01-01

48

Fast Diagnostic For Electrical Breakdowns In Vacuum  

SciTech Connect

The design of an inexpensive, small, high bandwidth diagnostic for the study of vacuum insulator flashover is described. The diagnostic is based on the principle of capacitive coupling and is commonly referred to as a D-dot probe due to its sensitivity to the changing of the electric displacement field. The principle challenge for the design proved to be meeting the required mechanical size for the application rather than bandwidth. An array of these probes was fabricated and used in an insulator test stand. Data from the test stand with detailed analysis is presented. A highlight of the application of the probes to the test stand was the ability to detect the charging of the insulator surface by UV illumination as a prelude to the insulator flashover. The abrupt change in the insulator's surface charge during the flashover was also detected.

Houck, T L; Javedani, J B; Lahowe, D A

2008-03-25

49

Breakdown characteristics of RTO 10 nm SiO2 films grown at different temperatures  

Microsoft Academic Search

Metal-oxide-semiconductor capacitors with 10 nm gate oxides grown by rapid thermal oxidation at temperatures of 1000, 1100 and 1150°C have been electrically characterized by means of C-V techniques, time-zero and time-dependent breakdown experiments. The oxides grown at higher temperatures show superior interfacial and oxide integrity characteristics, which is consistent with a lower level of intrinsic stress in such layers. The

L. Fonseca; F. Campabadal

1994-01-01

50

Breakdown characteristics of emitter-base and collector-base junctions of silicon bipolar junction transistors  

NASA Astrophysics Data System (ADS)

Recently, avalanche breakdown phenomena have received considerable attention. This is due to the lower breakdown voltage in advanced bipolar junction transistors (BJTs), which result from the increased collector doping. Avalanche breakdown in BJTs is an old issue; however, it is still not well-understood. This paper reports on studies of the breakdown characteristics of emitter-base and collector-base junctions with the other terminal open or shorted to the base. This is fundamental for the understanding of current-voltage characteristics of Si BJTs operated in the breakdown condition. The study includes the phenomena of avalanche breakdown, punchthrough and avalanche-induced light emission.

Jang, Sheng-Lyang; Chern, Kuang-Lang

1992-05-01

51

Space Charge Formation and Electrical Breakdown at High Temperature Region in PVC for Electrical Wiring Assembly  

NASA Astrophysics Data System (ADS)

The Polyvinyl chloride (PVC), the most popular insulating material, is used as an insulating material of various electric products. When using an electrical wiring assembly code over the power capacity, PVC could melt by the joule heating and cause an electrical breakdown. Therefore, it is necessary to clarify the electrical breakdown phenomena near the melting point (170°C) in PVC. In this paper, space charge distribution and conduction current have been measured in PVC sheets up to the electrical breakdown in the range from room temperature to 200°C under DC electric field. The breakdown strength decreases with temperature in PVC. Small hetero-space charges are accumulated near both of the electrodes at room temperature region. At high temperature region above 100°C, it is observed that positive charges are injected from anode and move toward the cathode; the electric field is emphasized near the cathode due to the packet-like positive charge in PVC. It shows a thermal breakdown process of the electric fields due to positive charge behavior and conduction current increase with temperature near the melting point in PVC.

Miura, Masakazu; Fukuma, Masumi; Kishida, Satoru

52

Mass spectra of neutral particles released during electrical breakdown of thin polymer films  

NASA Technical Reports Server (NTRS)

A special type of time-of-flight mass spectrometer triggered from the breakdown event was developed to study the composition of the neutral particle flux released during the electrical breakdown of polymer films problem. Charge is fed onto a metal-backed polymer surface by a movable smooth platinum contact. A slowly increasing potential from a high-impedance source is applied to the contact until breakdown occurs. The breakdown characteristics is made similar to those produced by an electron beam charging system operating at similar potentials. The apparatus showed that intense instantaneous fluxes of neutral particles are released from the sites of breakdown events. For Teflon FEP films of 50 and 75 microns thickness the material released consists almost entirely of fluorocarbon fragments, some of them having masses greater than 350 atomic mass units amu, while the material released from a 50 micron Kapton film consists mainly of light hydrocarbons with masses at or below 44 amu, with additional carbon monoxide and carbon dioxide. The apparatus is modified to allow electron beam charging of the samples.

Kendall, B. R. F.

1985-01-01

53

Electrical Breakdown in Lightning Arrestor Connector (LAC) Devices  

NASA Astrophysics Data System (ADS)

Lightning arrestor connector (LAC) devices protect electronic devices by providing a conductive path to ground for electrical power surges caused by lightning. Such devices consist of an insulating material between electrodes. This insulation region is composed of an air gap and a high permittivity dielectric. In this presentation, the physics of the phenomena active in the early stages of the flow of transient electrical current will be described. The conditions that lead to thermal breakdown of the dielectric will also be discussed.--Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Hjalmarson, Harold P.; Kambour, Kenneth; Pineda, Andrew C.

2011-03-01

54

Enhanced electric breakdown strength and high energy density of barium titanate filled polymer nanocomposites  

NASA Astrophysics Data System (ADS)

We report improved electric breakdown strength, high energy density, and low dielectric loss of nanocomposites using surface modified BaTiO3 (BT) nanoparticles filling in poly(vinylidene fluoride) polymer matrix. Dielectric and electric breakdown properties of the nanocomposites have been investigated as a function of BT content. The electric breakdown strength of 285 MV/m has been achieved at the nanocomposite with 10 vol. % BT nanoparticles. The results indicate that functionalized and produced passivation layers on the surface of ceramic fillers can improve the homogeneity of the nanocomposites, promote space charge and interface effects, and significantly enhance electric breakdown strength of the nanocomposites.

Yu, Ke; Niu, Yujuan; Xiang, Feng; Zhou, Yongcun; Bai, Yuanyuan; Wang, Hong

2013-11-01

55

The impact ionization and electrical breakdown strength for atomic and molecular liquids  

Microsoft Academic Search

It is pointed out that ionization electron avalanche development determines the electrical breakdown strength of the high-electron-mobility liquids Ar, Kr, and Xe. The DC and laser-induced breakdown strengths of these liquids are lower than low-density gas extrapolation values. This difference is the consequence of the absence of inelastic electron energy losses in liquids. In low-electron-mobility molecular liquids the electrical breakdown

V. M. Atrazhev; E. G. Dmitriev; I. T. Iakubov

1991-01-01

56

PZT 52\\/48 ferroelectric ceramics: Depolarization and electric breakdown under longitudinal explosive shock  

Microsoft Academic Search

Electric breakdown within longitudinally explosively shocked Pb(Zr0.52Ti0.48)O3 (PZT 52\\/48) ferroelectric ceramics was investigated. It was experimentally demonstrated that electric breakdown causes significant energy losses in miniature autonomous generators based on shock depolarization of poled ferroelectric elements. We found that a dependence of breakdown field strength, Eg, of shocked ferroelectric, on the thickness of the element, d, is described by the

S. I. Shkuratov; E. F. Talantsev; J. Baird

2011-01-01

57

Electrical breakdown properties of liquid nitrogen for electrical insulation design of pancake coil type HTS transformer  

Microsoft Academic Search

In the electrical insulation design of a pancake coil type high temperature superconducting (HTS) transformer, knowledge of the dielectric behavior of both liquid nitrogen (LN2) and gaseous nitrogen (GN2) is very important. Also, the breakdown strength under a quench conditions is an important factor of the insulation engineering. Since spacers are used in the pancake coil type HTS transformer, the

S. M. Baek; J. M. Joung; J. H. Lee; S. H. Kim

2003-01-01

58

Breakdown Characteristics of a Gas Mixed with Liquid Mist. Evaluation of Breakdown Strength under Quasi-Uniform Fields.  

National Technical Information Service (NTIS)

In order to clarify the breakdown characteristics of a gas mixed with liquid mist, flashover voltages were measured when N2 or SF6 gas was mixed with C2 Cl4 mist and influence of gas pressure, applied voltage and horizontal and vertical gap arrangements w...

M. Yashima H. Fujinami K. Takuma

1988-01-01

59

Influence of localized latent defects on electrical breakdown of thin insulators  

Microsoft Academic Search

Electrical breakdown in thin SiO2 films was measured with different techniques at different electric fields. It is shown that oxide reliability is affected by the presence of latent defects requiring a certain time to develop and evolve towards a destructive stage. As such a time is weakly dependent on applied fields, breakdown is not adequately detected by accelerated tests. It

Piero Olivo; Thao N. Nguyen; B. Ricco

1991-01-01

60

Electrical characteristics of natural and synthetic insulating fluids  

Microsoft Academic Search

Mineral oil with high insulation performance and cooling capability is currently used for oil-immersed transformers. However, mineral oil is derived from petroleum and thus is a limited resource. In a search for mineral oil substitutes, we investigated the characteristics of silicone and ester oils. The electrical performance was assessed in terms of the breakdown and streaming electrification characteristics and the

Satoshi Arazoe; Daisuke Saruhashi; Yuki Sato; Satoru Yanabu; Genyo Ueta; Shigemitsu Okabe

2011-01-01

61

Effect of electrode surface roughness on breakdown conditioning under non-uniform electric field in vacuum  

Microsoft Academic Search

Breakdown (BD) characteristics in vacuum are strongly dependent on the electrode surface conditions, such as surface roughness. However, there is little known concerning the details of the relationship between the surface roughness and BD conditioning effect. In practical application, it is important to clarify how the surface roughness affects the breakdown conditioning characteristics, especially for the non-uniform field configuration. This

K. Kato; Y. Fukuoka; H. Saitoh; M. Sakaki; H. Okubo

2007-01-01

62

Electrical breakdown and nanogap formation of indium oxide core/shell heterostructure nanowires  

NASA Astrophysics Data System (ADS)

We report the electrical breakdown behavior and subsequent nanogap formation of In2O3/InOx core/shell heterostructure nanowires with substrate-supported and suspended structures. The radial heterostructure nanowires, composed of crystalline In2O3 cores and amorphous In-rich shells, are grown by chemical vapor deposition. As the nanowires broke down, they exhibited two distinct current drops in the current-voltage characteristics. The tips of the broken nanowires were found to have a cone or a volcano shape depending on the width of the nanowire. The shape, the size, and the position of the nanogap depend strongly on the device structure and the nanowire dimensions. The substrate-supported and the suspended devices exhibit distinct breakdown behavior which can be explained by the diffusive thermal transport model. The breakdown temperature of the nanowire is estimated to be about 450 K, close to the melting temperature of indium. We demonstrated the usefulness of this technique by successful fabrication of working pentacene field-effect transistors.

Jung, Minkyung; Song, Woon; Lee, Joon Sung; Kim, Nam; Kim, Jinhee; Park, Jeunghee; Lee, Hyoyoung; Hirakawa, Kazuhiko

2008-12-01

63

Electrical Breakdown of Dielectrics with a Dipole Structure.  

National Technical Information Service (NTIS)

On the basis of data obtained in the breakdown of water and glycerine, as a function of the variation of the temperature, and also from data concerning breakdown voltages for ice, Seignette salt, and polar liquids, it follows that with the variation of th...

N. A. Prikhodko

1972-01-01

64

RESEARCH NOTES: Directional electric breakdown of KCl single crystals  

Microsoft Academic Search

Controversy exists about whether the discharge channel existing after breakdown in alkali halide crystals marks the path of the electronic instability or results from secondary processes. A fast electro-optical shutter has been used to observe the pre-breakdown light emission from KCl single crystals, and it has been found that the discharge channel does lie in the path of the electronic

R. Cooper; C. T. Elliott

1968-01-01

65

Pulsed breakdown voltage characteristics of pressurized carbon dioxide up to supercritical conditions  

Microsoft Academic Search

Statistical characteristics of pulsed breakdown voltage of pressurized carbon dioxide up to supercritical condition were investigated experimentally. The tested gap is a sphere-to-sphere and the gap length and sphere diameter are around 140 ¿m and 20 mm, respectively. The experimental results show the followings: 1) in the supercritical phase, the scattering in measured breakdown voltage increases with increasing the medium

T. Kiyan; K. Miyaji; T. Ihara; M. Hara; H. Akiyama

2009-01-01

66

Locating initial breakdown pulses using electric field change network  

NASA Astrophysics Data System (ADS)

Initial breakdown pulses (IBPs) observed in the fast electric field change (E-change) at the beginning of intracloud (IC) and cloud-to-ground (CG) lightning flashes are located using a time-of-arrival technique called Position By Fast Antenna (PBFA) with data from a network of 10 E-change sensors located at Kennedy Space Center. Location errors, estimated using a Monte Carlo method, are usually less than 100 m for horizontal coordinates and several hundreds of meters for altitude, depending on distance to the sensors and altitude of the source. Comparison of PBFA source locations to locations from a VHF lightning mapping system (Lightning Detection and Ranging II (LDAR2)) shows that PBFA locates most of the "classic" IBPs while LDAR2 locates only a few percent of them. As the flash develops during the IB stage, PBFA and LDAR2 obtain similar locations when they detect the same IBPs. The overall vertical motion indicated by the PBFA positions of IBPs was downward with time for CG flashes and upward with time for IC flashes. Location of the fast pulses due to return strokes of CG flashes is also determined using PBFA. Comparison to locations from the Cloud-to-Ground Lightning Surveillance System (CGLSS) shows that PBFA reliably locates ground strokes. These results are verified using ground truth data acquired with a high-speed video camera. After cross calibration with the CGLSS data set, peak currents of return strokes are also determined.

Karunarathne, Sumedhe; Marshall, Thomas C.; Stolzenburg, Maribeth; Karunarathna, Nadeeka; Vickers, Lauren E.; Warner, Tom A.; Orville, Richard E.

2013-07-01

67

THE ONSET OF ELECTRICAL BREAKDOWN IN DUST LAYERS: I. MICROSPARKING DESCRIBED BY PASCHEN'S LAW  

EPA Science Inventory

This paper describes a study of the onset of electrical breakdown in dust layers, for hand-deposited dust layers in a parallel-plate geometry. It was found that the breakdown was an ordinary electron-avalanche process originating in voids within the dust layer and obeying Paschen...

68

Effect of polar groups on the electrical breakdown strength of plasma-polymerized films  

Microsoft Academic Search

The electrical breakdown of plasma polymer films was studied by applying rectangular voltage pulses. Experimental evidence indicates that the breakdown field increases after incorporation of fluorine atoms into the film when the pulse width is <5 ?s. This is due to the scattering of electronic carriers caused by C-F bonds

T. Nakano; Masao Fukuyama; Hisaaki Hayashi; K. Ishii; Y. Ohki

1990-01-01

69

Technology Breakdown Structure of Physical and Performance Characteristics of Ocean Construction Platforms.  

National Technical Information Service (NTIS)

A technology breakdown structure (TBS) of the physical and performance characteristics (parametric descriptors) of O/C platforms is given. This is a systematic division/grouping of parametric descriptors into generic categories (TBS elements) that consist...

R. Taggart

1974-01-01

70

Breakdown characteristics of titanium dioxide–silicone–fluorophlogopite nanocomposite coating  

Microsoft Academic Search

In order to improve the high-voltage performance of organic insulators against flashover breakdown, a novel composite coating capable of conductive manipulation by the introduction of suitable amount of titanium dioxide photocatalytic semiconductor was proposed. This composite coating containing organic silicon, titanium dioxide and fluorophlogopite was fabricated on polyamide substrate by the brushing method. X-ray diffraction (XRD), scanning electron microscopy (SEM),

Yakui Bai; Yunhan Ling; Xinde Bai

2011-01-01

71

Bird Streamer Initiated Breakdown Characteristics under HVDC Conditions  

Microsoft Academic Search

A study of the role played by bird streamers (bird excretements) in transmission line faults under HVDC conditions is described in this paper. The research was initiated due to the lack of knowledge regarding this phenomenon. An insight is given as to what bird streamers faults are, and their role in the breakdown of air-gaps. A model HVDC transmission line

K. Naidoo; N. M. Ijumba; A. C. Britten

2006-01-01

72

DC conduction and electrical breakdown of MgO\\/LDPE nanocomposite  

Microsoft Academic Search

To understand basic electric properties of nano-sized magnesium oxide (MgO) \\/ low-density polyethylene (LDPE) nanocomposite under DC voltage application, the volume resistivity, the space charge distribution and the breakdown strength were investigated. By the addition of nano-sized MgO filler, both the DC breakdown strength and the volume resistivity of LDPE increased. At the average DC electric field of about 85

Yoshinobu Murakami; Masanori Nemoto; Syunsuke Okuzumi; Suguru Masuda; Masayuki Nagao; Naohiro Hozumi; Yoitsu Sekiguchi; Yoshinao Murata

2008-01-01

73

Numerical modeling of the electrical breakdown and discharge properties of laser-generated plasma channels.  

PubMed

An extensive nonequilibrium steady-state kinetics model incorporating collisional and radiative processes is developed to study the electrical breakdown and discharge maintenance of laser-induced atmospheric plasma channels formed in externally applied electric fields. The model is based upon a self-consistent numerical solution of the Boltzmann equation for the electron energy distribution function coupled with the electron energy balance equation and the population balance equations for electrons and air species. Using the electron energy distribution function, the ionization and electron attachment rates as a function of the reduced applied electric field at different degrees of ionization are calculated. We find that the ionization rate as a function of applied electric field in a laser-induced plasma channel is orders of magnitude larger than that obtained for a natural atmospheric air discharge. Therefore, the electrical breakdown of these plasma channels may occur at significantly lower applied electric fields. The present model predicts a breakdown electric field of 10kVcm , while the experimentally determined breakdown field strength is approximately 5.7kVcm [A. P. Baronavski, NRL Memorandum Report No. NRL/MR/6110-02-8642, 2002 (unpublished)], a reduction of about a factor of 5 from the natural Paschen electrical breakdown field of approximately 30kVcm . PMID:18233930

Petrova, Tz B; Ladouceur, H D; Baronavski, A P

2007-12-01

74

Numerical modeling of the electrical breakdown and discharge properties of laser-generated plasma channels  

SciTech Connect

An extensive nonequilibrium steady-state kinetics model incorporating collisional and radiative processes is developed to study the electrical breakdown and discharge maintenance of laser-induced atmospheric plasma channels formed in externally applied electric fields. The model is based upon a self-consistent numerical solution of the Boltzmann equation for the electron energy distribution function coupled with the electron energy balance equation and the population balance equations for electrons and air species. Using the electron energy distribution function, the ionization and electron attachment rates as a function of the reduced applied electric field at different degrees of ionization are calculated. We find that the ionization rate as a function of applied electric field in a laser-induced plasma channel is orders of magnitude larger than that obtained for a natural atmospheric air discharge. Therefore, the electrical breakdown of these plasma channels may occur at significantly lower applied electric fields. The present model predicts a breakdown electric field of 10 kV/cm, while the experimentally determined breakdown field strength is {approx}5.7 kV/cm [A. P. Baronavski et al., NRL Memorandum Report No. NRL/MR/6110-02-8642, 2002 (unpublished)], a reduction of about a factor of 5 from the natural Paschen electrical breakdown field of {approx}30 kV/cm.

Petrova, Tz. B.; Ladouceur, H. D.; Baronavski, A. P. [Molecular Dynamics Section, Chemistry Division, Naval Research Laboratory, 4555 Overlook Avenue, Washington, DC 20375 (United States)

2007-12-15

75

An investigation into the cumulative breakdown process of polymethylmethacrylate in quasi-uniform electric field under nanosecond pulses  

SciTech Connect

A group of complete images on the discharge channel developed in PMMA in quasi-uniform electric field under nanosecond pulses are observed with an on-line transmission microscope. The characteristics of the cumulative breakdown process are also generalized, which include initiating from the vicinity of the cathode, developing to the anode with a branch-like shape, and taking on a wormhole appearance when final breakdown occurs. The concluded characteristics are explained by referring to the conceptions of “low density domain” and “free radical” and considering the initial discharge channel as a virtual needle. The characteristics are helpful for designers to enhance the lifetime of insulators employed on a nanosecond time scale.

Zhao, Liang; Cang Su, Jian; Bo Zhang, Xi; Feng Pan, Ya; Min Wang, Li; Peng Fang, Jin; Sun, Xu; Lui, Rui [Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, P.O. Box 69 Branch 13, Xi'an 710024 (China)] [Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, P.O. Box 69 Branch 13, Xi'an 710024 (China)

2013-08-15

76

An investigation into the cumulative breakdown process of polymethylmethacrylate in quasi-uniform electric field under nanosecond pulses  

NASA Astrophysics Data System (ADS)

A group of complete images on the discharge channel developed in PMMA in quasi-uniform electric field under nanosecond pulses are observed with an on-line transmission microscope. The characteristics of the cumulative breakdown process are also generalized, which include initiating from the vicinity of the cathode, developing to the anode with a branch-like shape, and taking on a wormhole appearance when final breakdown occurs. The concluded characteristics are explained by referring to the conceptions of ``low density domain'' and ``free radical'' and considering the initial discharge channel as a virtual needle. The characteristics are helpful for designers to enhance the lifetime of insulators employed on a nanosecond time scale.

Zhao, Liang; Cang Su, Jian; Bo Zhang, Xi; Feng Pan, Ya; Min Wang, Li; Peng Fang, Jin; Sun, Xu; Lui, Rui

2013-08-01

77

A novel method for investigating electrical breakdown enhancement by nm-sized features.  

PubMed

Electrical transport studies across nm-thick dielectric films can be complicated, and datasets compromised, by local electrical breakdown enhanced by nm-sized features. To avoid this problem we need to know the minimal voltage that causes the enhanced electrical breakdown, a task that usually requires numerous measurements and simulation of which is not trivial. Here we describe and use a model system, using a "floating" gold pad to contact Au nanoparticles, NPs, to simultaneously measure numerous junctions with high aspect ratio NP contacts, with a dielectric film, thus revealing the lowest electrical breakdown voltage of a specific dielectric-nanocontact combination. For a 48 ± 1.5 Å SiO(2) layer and a ?7 Å monolayer of organic molecules (to link the Au NPs) we show how the breakdown voltage decreases from 4.5 ± 0.4 V for a flat contact, to 2.4 ± 0.4 V if 5 nm Au NPs are introduced on the surface. The fact that larger Au NPs on the surface do not necessarily result in significantly higher breakdown voltages illustrates the need for combining experiments with model calculations. This combination shows two opposite effects of increasing the particle size, i.e., increase in defect density in the insulator and decrease in electric field strength. Understanding the process then explains why these systems are vulnerable to electrical breakdown as a result of spikes in regular electrical grids. Finally we use XPS-based chemically resolved electrical measurements to confirm that breakdown occurs indeed right below the nm-sized features. PMID:22517579

Shpaisman, Hagay; Cohen, Hagai; Har-Lavan, Rotem; Azulai, Daniel; Stein, Nir; Cahen, David

2012-05-21

78

Studies on the temporal development of electrical breakdown in water  

Microsoft Academic Search

Pre-breakdown phenomena between a needle point of 5 ?m curvature and a plate, 100 ?m apart, in tap water have been studied with a spatial resolution of micrometers and a temporal resolution of 10 ns. The phenomena were observed by means of phase contrast microscopy. The illuminating light source was a flash lamp with a pulse duration of 10 ns.

F. Leipold; G. Yu; R. H. Stark; A. Abou-Ghazala; K. H. Schoenbach

2000-01-01

79

Relation between Electrical Impulse Breakdown Strength and Rate of Drawing in Polyethylene  

Microsoft Academic Search

The relation between electrical impulse breakdown strength and rate of drawing in films of low-density polyethylene is investigated. The rate of drawing is changed to cover the range from 2 mm\\/min to 60 mm\\/min, and the drawing temperature is from 20 to 60°C. The impulse breakdown strength is measured at ca.20°C after drawing at various drawing temperatures. The draw ratio

Kichinosuke Yahagi; Keiji Isshiki; Haruyasu Imada

1979-01-01

80

REVIEWS OF TOPICAL PROBLEMS: Runaway breakdown and electric discharges in thunderstorms  

Microsoft Academic Search

This review concerns the theory of the avalanche multiplication of high-energy (0.1 - 10 MeV) electrons in a neutral material, a newly discovered phenomenon known as runaway breakdown (RB). In atmospheric conditions RB takes place at electric fields an order of magnitude weaker than those needed for normal breakdown in air. Experimental work of the past few years has shown

Aleksandr V. Gurevich; Kirill P. Zybin

2001-01-01

81

Aromatic polythiourea dielectrics with ultrahigh breakdown field strength, low dielectric loss, and high electric energy density.  

PubMed

The promise of aromatic, amorphous, polar polymers containing high dipolar moments with very low defect levels is demonstrated for future dielectric materials with ultrahigh electric-energy density, low loss at high applied fields, and ultrahigh breakdown strengths. Specifically, aromatic polythiourea films exhibit an ultrahigh breakdown field (>1 GV m(-1)), which results in an energy density of ?22 J cm(-3), as well as a low loss. PMID:23315675

Wu, Shan; Li, Weiping; Lin, Minren; Burlingame, Quinn; Chen, Qin; Payzant, Andrew; Xiao, Kai; Zhang, Q M

2013-03-25

82

Influence of magnetic field on the electric breakdown in penning ion source  

Microsoft Academic Search

A cold-cathode penning-type ion source has been developed in our laboratory to study the electric breakdown in this type of sources. The breakdown voltage was measured as a function of axial magnetic field, in the range of 440–600 G, and anode length, in steps of 14, 20, and 24 mm. The measurement was performed with stainless steel cathodes in argon

M. Mahjour-Shafiei; H. Noori; A. H. Ranjbar

2011-01-01

83

Study of electric breakdown of liquid dielectrics using Schlieren optical techniques  

Microsoft Academic Search

The work is a contribution to the understanding of the mechanism of electric breakdown in liquid dielectrics. The liquid dielectric chosen throughout the experiments was n-hexane, because an extensive literature exists on the breakdown of this material. The applied voltage was a rectangular pulse of different durations supplied from a 125 kv, five-stage Marx-Goodlet impulse generator. A novel rotary multiple

B. Farazmand

1961-01-01

84

Investigation of the breakdown products produced from electrical discharge in selected CFC replacement fluids  

SciTech Connect

LLNL personnel have designed and constructed a special purpose electrical test stand to evaluate CFCs and CFC replacement fluids under simulated AC, DC, and pulsed breakdown conditions. The test stand includes an electrical diagnostic system which allows the measurement of breakdown voltage, discharge current, arc power, and energy associated with each pulse. The appropriate data that is collected in order to correlate the quantity of by-products produced with the pertinent control variables, such as voltage, current, pulse width, pulse repetition frequency, and energy. Along with the electrical test stand, LLNL has extensive chemical analysis facilities that enable us to perform gas chromatographic and gas chromatographic-mass spectrometric analysis of various fluids to identify and quantify the breakdown products formed under various scenarios of electrical energy deposition.

Hawley-Fedder, R.; Goerz, D.; Koester, C.; Wilson, M.

1996-04-01

85

Analytical investigation of electrical breakdown properties in a nitrogen-SF{sub 6} mixture gas  

SciTech Connect

The electrical breakdown properties in nitrogen gas mixed with SF{sub 6} are analytically investigated in this article by making use of the ionization and attachment coefficients of the mixed gas. The ionization coefficients of nitrogen and SF{sub 6} gas are obtained in terms of the electron temperature T{sub e} by assuming a Maxwellian distribution of the electron energy. The attachment coefficient of SF{sub 6} gas is also obtained in terms of the gas temperature T{sub e}. An algebraic equation is obtained, relating explicitly the electron breakdown temperature T{sub b} in terms of the SF{sub 6} mole fraction {chi}. It was found from this equation that the breakdown temperature T{sub b} increases from approximately 2 to 5.3 eV as the mole fraction {chi} increases from zero to unity. The breakdown temperature T{sub b} of the electrons increases very rapidly from a small value and then approaches 5.3 eV slowly as the SF{sub 6} mole fraction increases from zero to unity. This indicates that even a small mole fraction of SF{sub 6} in the gas dominates the electron behavior in the breakdown system. The breakdown electric field E{sub b} derived is almost linearly proportional to the breakdown electron temperature T{sub b}. The experimental data agree remarkably well with the theoretical results. Therefore, it is concluded that even a small fraction of SF{sub 6} gas dominates nitrogen in determining the breakdown field. In this context, nearly 25% of the SF{sub 6} mole fraction provides a reasonable enhancement of the breakdown field for practical applications.

Uhm, Han S. [Kwangwoon Academy of Advanced Studies, Kwangwoon University, 447-1, Wolgye-Dong, Nowon-Gu, Seoul 137-701 (Korea, Republic of); Byeon, Yong S.; Song, Ki B.; Choi, Eun H. [Department of Electrophysics, Kwangwoon University, 447-1, Wolgye-Dong, Nowon-Gu, Seoul 137-701 (Korea, Republic of); Ryu, Han-Yong; Lee, Jaimin [Agency for Defense Development, 462 Jochiwongil, Yuseong, Daejeon 305-605 (Korea, Republic of)

2010-11-15

86

Impulse breakdown conditioning process under non-uniform electric field in vacuum  

Microsoft Academic Search

This paper describes an experimental investigation of impulse conditioning effect in vacuum by analyzing the history of sequential breakdown (BD) and the relationship between the migration of BD spots and the variation of electric field strength for nonuniform electric field distribution. From the experimental results, the authors found \\

H. Okubo; H. Wanibe; F. Miyazaki; K. Kato; T. Shioiri

2002-01-01

87

Analysis of the polarity effects in the electrical breakdown of liquids.  

SciTech Connect

Electrical breakdown simulations are carried out for liquids in response to a sub-microsecond ({approx}100-200 ns) voltage pulse. This model builds on our previous analysis and focuses particularly on the polarity effect seen experimentally in point-plane geometries. The flux-corrected transport approach is used for the numerical implementation. Our model adequately explains experimental observations of pre-breakdown current fluctuations, streamer propagation and branching as well as disparities in hold-off voltage and breakdown initiation times between the anode and cathode polarities. It is demonstrated that polarity effects basically arise from the large mobility difference between electrons and ions. The higher electron mobility leads to greater charge smearing and diffusion that impacts the local electric field distributions. Non-linear couplings between the number density, electric field and charge generation rates then collectively affect the formation of ionized channels and their temporal dynamics.

Woodworth, Joseph Ray; Qian, J. (Old Dominion University, Norfolk, VA); Joshi, Ravindra P. (Old Dominion University, Norfolk, VA); Schamiloglu, Edl (University of New Mexico, Albuquerque, NM); Gaudet, John A. (University of New Mexico, Albuquerque, NM); Lehr, Jane Marie

2005-03-01

88

Electric field enhancement during gap breakdown by ionization waves in nitrogen at elevated pressure  

NASA Astrophysics Data System (ADS)

The breakdown of an interelectrode gap filled with nitrogen and some other gases at elevated pres- sure has been studied in an inhomogeneous electric field generated by high-voltage pulses applied to sharp blade electrodes. It is established that the gap breakdown is produced by counterpropagating diffuse plasma jets originating from the two electrodes. The jets merge together and shorten the gap in the axial direction and at angles relative to the electric field lines. The measurements of the laser generation in nitrogen at ? = 337.1 nm showed that, at elevated gas pressures, the electric field in the region of breakdown between coun- terpropagating jets is enhanced, while the intensity of the discharge plasma glow in this region is lower than in the other parts of the gap.

Tarasenko, V. F.; Tel'Minov, A. E.; Burachenko, A. G.

2011-03-01

89

Breakdown mechanisms and reverse current-voltage characteristics of organic bulk heterojunction solar cells and photodetectors  

NASA Astrophysics Data System (ADS)

We investigate the reverse current-voltage characteristics and breakdown mechanisms of organic bulk heterojunction solar cells and photodetectors. Dark current and photo current measurements at different temperatures indicate that tunneling is the dominant mechanism at high reverse voltage. A band-to-band tunneling model that accommodates either Gaussian or exponential-parabolic density of states distributions is developed and used for simulations. At high reverse bias, the model explains the observed breakdown, which differs from the bias independent dark current behavior predicted by the Onsager-Braun model. At low reverse voltage, the incorporation of shunt resistance in the model provides good agreement between the measured reverse bias characteristics and simulations.

Li, Kejia; Li, Lijun; Khlyabich, Petr P.; Burkhart, Beate; Sun, Wenlu; Lu, Zhiwen; Thompson, Barry C.; Campbell, Joe C.

2014-06-01

90

Streamer formation in electric fields above and below the breakdown threshold  

NASA Astrophysics Data System (ADS)

Streamers are rapidly growing plasma filaments that can penetrate into non-ionized regions due to the electric field enhancement at their tips. They play a key role in the early stages of many atmospheric discharges, for example in lightning inception, in the streamer coronas of lightning leaders and of jets, and in sprite discharges. There are positive and negative streamers. Positive streamers propagate along the direction of the electric field, while negative streamers propagate in the opposite direction. With fully three-dimensional particle simulations, we study the combined effect of natural background ionization, electron detachment and photoionization on the formation of streamers in atmospheric air. We use adaptive grid refinement and adaptive particle management, and we have parallelized our particle code. We show that in electric fields below the breakdown threshold, positive streamers can only form if there is a strong initial seed present. Negative streamers fail to originate, at least on the time scales we have considered. In electric fields above the breakdown threshold, the situation is very different. New avalanches continuously form all over the domain. They originate from free electrons, which can be created by photoionization or by detachment from negative ions. Instead of the "double-headed" streamers that show up in most fluid models, we observe a more uniform discharge. We conclude that single elongated streamers exist only if the overall background electric field is below the breakdown value. The local field at the streamer head, of course, has to exceed the breakdown field.

Sun, Anbang; Teunissen, Jannis; Koehn, Cristoph; Ebert, Ute

2013-04-01

91

Methods to increase electrical breakdown threshold of polystyrene insulators  

Microsoft Academic Search

This paper discusses experimental studies conducted to determine the effects of methods used to increase the electrical stress limit of polystyrene dielectric samples. Surfaces of samples were laser annealed to create a more uniform surface and decrease voids where charge may accumulate. Geometry of the dielectric samples were considered with the aim of reducing electric field intensity at the triple

Jennifer L. Zirnheld; Kevin M. Burke; Shola Olabisi; Jahmil Campbell; Harry Moore; Dave Singh

2009-01-01

92

Electric breakdown strength of aromatic polymers: dependence on film thickness and chemical structure  

Microsoft Academic Search

The AC electric breakdown field strength FB of aromatic polymer films as a function of sample thickness was investigated. A power-law dependence of FB on sample thickness was found. The exponential parameter of the power law was shown to correlate with the electron accepting properties of the polymer. Reasonable values of the electron accepting properties of the polymers were assigned

Bertil Helgee; Peter Bjellheim

1991-01-01

93

Electron waves in the electrical breakdown of gases, with application to the dart leader in lightning  

Microsoft Academic Search

The fluid dynamical analysis of an electron gas has been recently reviewed and applied to the final stages of an electrical breakdown in gases at atmospheric pressure. In particular, it has been used to describe the wavelike propagation of luminous pulses (ionizing waves) that move with speeds of 106-107 m\\/s. Because of the complexity of the fluid equations, the usual

H. Jurenka; E. Barreto

1985-01-01

94

High Speed Laser Schlieren Studies of Electrical Breakdown in Liquid Hydrocarbons  

Microsoft Academic Search

The events occurring just prior, during, and after electrical break-down in liquid hydrocarbons have been photographed using 15 ns laser pulses produced with a ruby laser, to illuminate the space between two parallel plate electrodes, and schlieren optics. In this manner it was possible to obtain experimental evidence of the density gradients produced by the movement of charge carriers during

E. O. Forster; P. Wong

1977-01-01

95

Electric Field Breakdown of Charge-Density-Wave-Induced Anomalies in NbSe3  

Microsoft Academic Search

We report the suppression by electric fields of longitudinal resistivity anomalies at 145 and 59 K in the compound NbSe3. Sample resistance was determined by conventional four-probe dc measurement as well as with short current pulses. We attribute the observed suppression to Zener breakdown across extremely small gaps introduced by the presence of charge density waves.

P. Monçeau; N. P. Ong; A. M. Portis; A. Meerschaut; J. Rouxel

1976-01-01

96

An advanced no-snapback LDMOSFET with optimized breakdown characteristics of drain n-n+ diodes  

Microsoft Academic Search

Snapbacks in sustain characteristics of lateral double-diffused MOSFETs (LDMOSFETs) are caused by positive feedbacks between the turn-on of the bipolar junction transistors (BJTs) and the avalanche breakdown of the drain n-n+ diodes . Although the n-n+ diodes are thus one of the most basic parasitic devices, which play a leading role in the snapback characteristics, neither a textbook nor a

Kazunori Kawamoto; Shigeki Takahashi

2004-01-01

97

Mass spectrometric studies of the electrical breakdown of thin polymer films  

NASA Technical Reports Server (NTRS)

The composition of the neutral particles released during the electrical breakdown of 50-micron and 75-micron insulating films of the type used on spacecraft exteriors investigated experimentally using a time-of-flight mass spectrometer triggered by the breakdown event. The experimental apparatus is described in detail, and the results are presented in photographs. It is found that the particle flux from Teflon FEP and PFA films comprise mainly fluorocarbon fragments, some with mass 350 amu or greater, but the flux from Kapton oxygen-ion-beam treated Kapton, Tefzel, and Mylar comprises mainly molecules of mass 44 amu or less.

Kendall, B. R. F.; Rohrer, V. S.; Bojan, V. J.

1986-01-01

98

Electrical conduction and breakdown properties of silicon nitride films  

Microsoft Academic Search

The electrical conduction properties of ion-plated silicon nitride films in the form of aluminium-silicon nitride-aluminium structures have been studied in the temperature range 300 K to 470 K. The results obtained in the d.c. Conduction studies have been explained on the basis of the Poole-Frenkel conduction mechanism. The a.c. conduction studies in the frequency range 500 Hz to 30 kHz

D. Mangalaraj; M. Radhakrishnan; C. Balasubramanian

1982-01-01

99

A system for gas electrical breakdown time delay measurements based on a microcontroller  

NASA Astrophysics Data System (ADS)

A new system, called gasmem v1.0, for the measurements of gas electrical breakdown time delay (td), with significantly better characteristics than older systems, has been developed and realized. It is based on the PIC 18F4550 microcontroller and could measure the minimal td of about 1.5 ?s with the resolution of 83.33 ns. The relaxation (afterglow) period (?) could vary from 1 to 232 ms (?50 days). The successive series of td measurements with various ? could be performed, giving very reliable td data that are stored on the personal computer (PC) hard drive via the USB interface. The td and ? values enable the drawing of memory curves (langtdrang = f(?)) and the analysis of memory effects in the gases. The randomness of td values measured by the gasmem system for more ? values was tested using the nonparametric Wald-Wolfowitz test showing the stochastic nature of obtained results. The memory curves obtained by this system have shown very high reproducibility. In addition, the system has a capability of operating as a stand-alone system (independently of a PC), with the possibility for the implementation of a touch screen for controlling the system and additional memory (e.g. memory card) for data storage.

Todorovi?, Miomir; Vasovi?, Nikola D.; Risti?, Goran S.

2012-01-01

100

Mass analysis of neutral particles and ions released during electrical breakdowns on spacecraft surfaces  

NASA Technical Reports Server (NTRS)

Charged-particle fluxes from breakdown events were studied. Methods to measure mass spectra and total emitted flux of neutral particles were developed. The design and construction of the specialized mass spectrometer was completed. Electrical breakdowns were initiated by a movable blunt contact touching the insulating surface. The contact discharge apparatus was used for final development of two different high-speed recording systems and for measurements of the composition of the materials given off by the discharge. It was shown that intense instantaneous fluxes of neutral particles were released from the sites of electrical breakdown events. A laser micropulse mass analyzer showed that visible discoloration at breakdown sites were correllated with the presence of iron on the polymer side of the film, presumably caused by punch-through to the Inconel backing. Kapton samples irradiated by an oxygen ion beam were tested. The irradiated samples were free of surface hydrocarbon contamination but otherwise behaved in the same way as the Kapton samples tested earlier. Only the two samples exposed to oxygen ion bombardment were relatively clean. This indicates an additional variable that should be considered when testing spacecraft materials in the laboratory.

Kendall, B. R. F.

1985-01-01

101

Influence of magnetic field on the electric breakdown in penning ion source  

NASA Astrophysics Data System (ADS)

A cold-cathode penning-type ion source has been developed in our laboratory to study the electric breakdown in this type of sources. The breakdown voltage was measured as a function of axial magnetic field, in the range of 440-600 G, and anode length, in steps of 14, 20, and 24 mm. The measurement was performed with stainless steel cathodes in argon gas at pressure of 4 × 10-2 mbar. Furthermore, a model was developed to explain the breakdown voltage data. In the construction of the model, the first Townsend coefficient was not directly used to avoid difficulties originating from the non-uniformity of the electric field. The empirical parameters of the model were obtained using the experimental data. The equation ? = c × (Ez/N)n, expressing the effective secondary emission coefficient in terms of reduced electric field, which was needed in the modeling process, was inspired from previous works. The parameters c and n were then calculated from the empirical parameters of the model. The n parameter turned out to be 0.59, which differs from the value reported by other authors merely by 1.6%. Three values, 0.010, 0.013, and 0.017 corresponding to the three anodes were obtained for the c parameter. These numbers are in good agreement with 0.01, which has been reported in the previous works. It was also found that the value of n has a decisive impact on the breakdown voltage curve in the high breakdown voltage region.

Mahjour-Shafiei, M.; Noori, H.; Ranjbar, A. H.

2011-11-01

102

Influence of magnetic field on the electric breakdown in penning ion source.  

PubMed

A cold-cathode penning-type ion source has been developed in our laboratory to study the electric breakdown in this type of sources. The breakdown voltage was measured as a function of axial magnetic field, in the range of 440-600 G, and anode length, in steps of 14, 20, and 24 mm. The measurement was performed with stainless steel cathodes in argon gas at pressure of 4 × 10(-2) mbar. Furthermore, a model was developed to explain the breakdown voltage data. In the construction of the model, the first Townsend coefficient was not directly used to avoid difficulties originating from the non-uniformity of the electric field. The empirical parameters of the model were obtained using the experimental data. The equation ? = c × (E(z)/N)(n), expressing the effective secondary emission coefficient in terms of reduced electric field, which was needed in the modeling process, was inspired from previous works. The parameters c and n were then calculated from the empirical parameters of the model. The n parameter turned out to be 0.59, which differs from the value reported by other authors merely by 1.6%. Three values, 0.010, 0.013, and 0.017 corresponding to the three anodes were obtained for the c parameter. These numbers are in good agreement with 0.01, which has been reported in the previous works. It was also found that the value of n has a decisive impact on the breakdown voltage curve in the high breakdown voltage region. PMID:22128971

Mahjour-Shafiei, M; Noori, H; Ranjbar, A H

2011-11-01

103

Electrical breakdown strength of 5 kV imperfect XLPE cable after combined AC-DC excitation  

Microsoft Academic Search

Electrical breakdown strength of 5 kV imperfect XLPE cable under different combined AC-DC excitation is studied. Two types of imperfect cable samples were used in this research: cable samples with artificial holes inside the insulation and cable samples with embedded metal needles. A comparison of the breakdown voltage under pulsating excitation for imperfect and sound cable shows that the pulsating

S. Grzybowski; J. Fan

1996-01-01

104

Impurity breakdown and electric-field-dependent luminescence in MBE and VPE GaAs layers  

NASA Astrophysics Data System (ADS)

Impurity avalanche breakdown in n-type GaAs layers prepared by the LPE, VPE and MBE methods has been studied in detail using voltage-controlled current-voltage (I-V) characteristics and luminescence measurements together with computer simulations. Scholl's model of the first-order non-equilibrium phase transition in a two-level system was found to be adequate to describe the main experimental results. The threshold voltage for breakdown depends on the initial free-electron concentration. The hysteresis width diminishes with decreasing binding energy of electrons in the excited states of donors. The changes in luminescence spectra observed during impurity breakdown reflect changes in the charge state of shallow impurities. The band corresponding to D-A transitions disappears together with the decrease of the exciton radiative recombination rate. In the post-breakdown part of the I-V characteristics another region of nonlinear behaviour with hysteresis and sharp increase of instabilities was observed. Its origin has not yet been determined unambiguously.

Karel, F.; Oswald, J.; Pastrnak, J.; Petricek, O.

1992-02-01

105

Impulse breakdown mechanism based on discharge propagation process under non-uniform electric field in air  

Microsoft Academic Search

In this paper, we aim to clarify the discharge mechanism leading to breakdown under non-uniform electric field in air, especially on the propagation process of discharge current channel. The discharge measurement was performed in a needle (?1 mm)-plane electrode system with gap length g=15–100 mm in 0.1 MPa dry air under applying a positive impulse voltage. We observed discharge current

Katsuki Hotta; Takeshi Iwata; Hiroki Kojima; Naoki Hayakawa; Norihito Yanagita; Tatsuro Kato; Toshiaki Rokunohe; Hitoshi Okubo

2011-01-01

106

Electrical breakdown strength of XLPE cables under combined AC-DC voltage  

Microsoft Academic Search

This paper presents data on electrical breakdown strength of 5 kV XLPE cable under AC voltages, DC voltages, and superimposed AC upon DC voltages. In the latter case, the ratio of the AC to DC voltage components (p=Vac\\/Vdc) was varied between the limits of 0.04

S. Grzybowski; R. L. McMellon

1995-01-01

107

The influence of morphology on the electrical breakdown strength of polypropylene film  

Microsoft Academic Search

The relationship between the microscopic structure morphology and the electrical strength of polypropylene (PP) film used in PP-laminated paper (PPLP) in very high voltage oil-filled cable is studied by several methods including infrared spectrum, X-ray diffraction and dynamic mechanical spectra. It is found that the key to improve the breakdown strength, the tensile strength and the stability in oil for

L. Y. Gao; D. M. Tu; S. C. Zhou; Z. L. Zhang

1990-01-01

108

Imaging the Effect of Electrical Breakdown in Multilayer Polymer Capacitor Films  

NASA Astrophysics Data System (ADS)

Multilayer polymer films show great promise as the dielectric material in high energy density capacitors. Such films show enhancement in both dielectric strength (EB) and energy density (Ud) relative to monolithic films of either source polymer. Composites are typically comprised of alternating layers of a high EB polymer and a high permittivity polymer. Here, we discuss a multilayer system based on polycarbonate (PC) interleaved with polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP). The dielectric properties of the PC/PVDF-HFP films are influenced by both composition and individual layer thickness. Optimized films show EB=750 kV/mm and Ud=13 J/cm^3. Further enhancements in EB and Ud are expected through optimization of the component polymers, composition, and layer structure. To guide next generation design, it is important to understand the breakdown mechanism, as it directly influences EB. To elucidate the role of the layer structure during electrical breakdown, we use a tandem focused ion beam (FIB) / scanning electron microscope (SEM) imaging technique. The technique allows us to image the internal layer structure of both `as fabricated' control films, and those subjected to high electric fields. It is therefore a powerful tool to assess film quality and analyze failure mechanisms. Specifically, the FIB is used to mill site-specific holes in a film and the resulting cross-sections are imaged via SEM. Individual layers are easily resolved down to 50 nm. For films subjected to electrical breakdown, the location and propagation of damage is tracked with sequential FIB milling and SEM imaging. Spatially resolved FIB/SEM imaging allows preparation of quasi-3D maps displaying the evolution of internal voids in areas adjacent to the breakdown location (pinhole of d = 30-80 microns). A majority of the voids are localized at the interfaces between layers and may propagate as far as 30-50 microns from the pinhole. The data suggest that the enhancement in dielectric strength arises from a barrier effect, whereby the propagation of an electrical breakdown in the direction of the applied field is impeded by the layer interfaces. We will also discuss recent TEM imaging results that are used to characterize the interfacial length scale and chemical makeup, factors that may influence breakdown.

Wolak, Mason

2013-03-01

109

Characteristics of decentralized electricity generation  

SciTech Connect

The characteristics of decentralized electricity generation are examined at several different levels with the aid of twenty-three independent variables. This approach provides a systematic framework for assessing and comparing the decentralized nature of power generation facilities and systems. While the analysis reveals that decentralization is not an explicit measure of performance, the taxonomy provides a useful tool for improving the quality of the debate on this issue.

Hyman, B.; Bereano, P.L.; King, S.

1984-01-01

110

DOE Task Force meeting on Electrical Breakdown of Insulating Ceramics in a High Radiation Field  

SciTech Connect

This volume contains the abstracts and presentation material from the Research Assistance Task Force Meeting Electrical Breakdown of Insulating Ceramics in a High-Radiation Field.'' The meeting was jointly sponsored by the Office of Basic Energy Sciences and the Office of Fusion Energy of the US Department of Energy in Vail, Colorado, May 28--June 1, 1991. The 26 participants represented expertise in fusion, radiation damage, electrical breakdown, ceramics, and semiconductor and electronic structures. These participants came from universities, industries, national laboratories, and government. The attendees represented eight nations. The Task Force meeting was organized in response to the recent discovery that a combination of temperature, electric field, and radiation for an extended period of time has an unexplained adverse effect in ceramics, termed radiation-enhanced electrical degradation (REED). REED occurs after an incubation period and continues to accelerate with irradiation until the ceramics can no longer be regarded as insulators. It appears that REED is irreversible and the ceramic insulators cannot be readily annealed or otherwise repaired for future services. This effect poses a serious threat for fusion reactors, which require electrical insulators in diagnostic devices, in radio frequency and neutral beam systems, and in magnetic assemblies. The problem of selecting suitable electrical insulating materials in thus far more serious than previously anticipated.

Green, P.H. (comp.) [comp.

1991-08-01

111

Effects of thermal and electrical stressing on the breakdown behavior of space wiring  

NASA Astrophysics Data System (ADS)

Several failures in the electrical wiring systems of many aircraft and space vehicles have been attributed to arc tracking and damaged insulation. In some instances, these failures proved to be very costly as they have led to the loss of many aircraft and imperilment of space missions. Efforts are currently underway to develop lightweight, reliable, and arc track resistant wiring for aerospace applications. In this work, six wiring constructions were evaluated in terms of their breakdown behavior as a function of temperature. These hybrid constructions employed insulation consisting of Kapton, Teflon, and cross-linked Tefzel. The properties investigated included the 400 Hz AC dielectric strength at ambient and 200 C, and the lifetime at high temperature with an applied bias of 40, 60, and 80% of breakdown voltage level. The results obtained are discussed, and conclusions are made concerning the suitability of the wiring constructions investigated for aerospace applications.

Hammoud, Ahmad; Stavnes, Mark; Suthar, Jayant; Laghari, Javaid

1995-06-01

112

Experimental study of electric breakdowns in liquid argon at centimeter scale  

NASA Astrophysics Data System (ADS)

In this paper we present results on measurements of the dielectric strength of liquid argon near its boiling point and cathode-anode distances in the range of 0.1 mm to 40 mm with spherical cathode and plane anode. We show that at such distances the applied electric field at which breakdowns occur is as low as 40 kV/cm. Flash-overs across the ribbed dielectric of the high voltage feed-through are observed for a length of 300 mm starting from a voltage of 55 kV. These results contribute to set reference for the breakdown-free design of ionization detectors, such as Liquid Argon Time Projection Chambers (LAr TPC).

Blatter, A.; Ereditato, A.; Hsu, C.-C.; Janos, S.; Kreslo, I.; Luethi, M.; von Rohr, C. Rudolf; Schenk, M.; Strauss, T.; Weber, M. S.; Zeller, M.

2014-04-01

113

Effects of thermal and electrical stressing on the breakdown behavior of space wiring  

NASA Technical Reports Server (NTRS)

Several failures in the electrical wiring systems of many aircraft and space vehicles have been attributed to arc tracking and damaged insulation. In some instances, these failures proved to be very costly as they have led to the loss of many aircraft and imperilment of space missions. Efforts are currently underway to develop lightweight, reliable, and arc track resistant wiring for aerospace applications. In this work, six wiring constructions were evaluated in terms of their breakdown behavior as a function of temperature. These hybrid constructions employed insulation consisting of Kapton, Teflon, and cross-linked Tefzel. The properties investigated included the 400 Hz AC dielectric strength at ambient and 200 C, and the lifetime at high temperature with an applied bias of 40, 60, and 80% of breakdown voltage level. The results obtained are discussed, and conclusions are made concerning the suitability of the wiring constructions investigated for aerospace applications.

Hammoud, Ahmad; Stavnes, Mark; Suthar, Jayant; Laghari, Javaid

1995-01-01

114

Application of dynamic displacement current for diagnostics of subnanosecond breakdowns in an inhomogeneous electric field  

NASA Astrophysics Data System (ADS)

The breakdown of different air gaps at high overvoltages in an inhomogeneous electric field was investigated with a time resolution of up to 100 ps. Dynamic displacement current was used for diagnostics of ionization processes between the ionization wave front and a plane anode. It is demonstrated that during the generation of a supershort avalanche electron beam (SAEB) with amplitudes of ~10 A and more, conductivity in the air gaps at the breakdown stage is ensured by the ionization wave, whose front propagates from the electrode of small curvature radius, and by the dynamic displacement current between the ionization wave front and the plane electrode. The amplitude of the dynamic displacement current measured by a current shunt is 100 times greater than the SAEB. It is shown that with small gaps and with a large cathode diameter, the amplitude of the dynamic displacement current during a subnanosecond rise time of applied pulse voltage can be higher than 4 kA.

Shao, Tao; Tarasenko, Victor F.; Zhang, Cheng; Burachenko, Alexandr G.; Rybka, Dmitry V.; Kostyrya, Igor'D.; Lomaev, Mikhail I.; Baksht, Evgeni Kh.; Yan, Ping

2013-05-01

115

Protein Preconcentration Using Nanofractures Generated by Nanoparticle-Assisted Electric Breakdown at Junction Gaps  

PubMed Central

Sample preconcentration is an important step that increases the accuracy of subsequent detection, especially for samples with extremely low concentrations. Due to the overlapping of electrical double layers in the nanofluidic channel, the concentration polarization effect can be generated by applying an electric field. Therefore, a nonlinear electrokinetic flow is induced, which results in the fast accumulation of proteins in front of the induced ionic depletion zone, the so-called exclusion-enrichment effect. Nanofractures were created in this work to preconcentrate proteins via the exclusion-enrichment effect. The protein sample was driven by electroosmotic flow and accumulated at a specific location. The preconcentration chip for proteins was fabricated using simple standard soft lithography with a polydimethylsiloxane replica. Nanofractures were formed by utilizing nanoparticle-assisted electric breakdown. The proposed method for nanofracture formation that utilizes nanoparticle deposition at the junction gap between microchannels greatly decreases the required electric breakdown voltage. The experimental results indicate that a protein sample with an extremely low concentration of 1 nM was concentrated to 1.5×104-fold in 60 min using the proposed chip.

Jen, Chun-Ping; Amstislavskaya, Tamara G.; Kuo, Chen-Chi; Chen, Yu-Hung

2014-01-01

116

Electrical Breakdown of Anodized Structures in a Low Earth Orbital Environmental  

NASA Technical Reports Server (NTRS)

A comprehensive set of investigations involving arcing on a negatively biased anodized aluminum plate immersed in a low density argon plasma at low pressures (P(sub O), 7.5 x 10(exp -5) Torr) have been performed. These arcing experiments were designed to simulate electrical breakdown of anodized coatings in a Low Earth Orbital (LEO) environment. When electrical breakdown of an anodized layer occurs, an arc strikes, and there is a sudden flux of electrons accelerated into the ambient plasma. This event is directly followed by ejection of a quasi-neutral plasma cloud consisting of ejected material blown out of the anodized layer. Statistical analysis of plasma cloud expansion velocities have yielded a mean propagation velocity, v = (19.4 +/- 3.5) km/s. As the plasma cloud expands into the ambient plasma, energy in the form of electrical noise is generated. The radiated electromagnetic noise is detected by means of an insulated antenna immersed in the ambient plasma. The purpose of the investigations is (1) to observe and record the electromagnetic radiation spectrum resulting from the arcing process. (2) Make estimates of the travel time of the quasi-neutral plasma cloud based on fluctuations to several Langmuir probes mounted in the ambient plasma. (3) To study induced arcing between two anodized aluminum structures in close proximity.

Galofaro, J. T.; Doreswamy, C. V.; Vayner, B. V.; Snyder, D. B.; Ferguson, D. C.

1999-01-01

117

Dielectric breakdown via emergent nonequilibrium steady states of the electric-field-driven Mott insulator  

NASA Astrophysics Data System (ADS)

In this work, we explore the possibility of emergent nonequilibrium steady states arising from the electric-field-driven Mott insulator via the Keldysh-Floquet dynamical mean-field theory (DMFT), which can determine the fully interacting, nonequilibrium steady-state Green's functions with the noninteracting counterparts as an input to the DMFT self-consistency loop. Unlike the retarded component, obtaining the lesser Green's function for the noninteracting system presents an important obstacle since the thermalization of the noninteracting system still requires a precise understanding of the dissipation mechanism. A crucial breakthrough in this work is that the noninteracting lesser Green's function can be determined in terms of the Wannier-Stark ladder (WSL) eigenstates, which are thermalized via the standard canonical ensemble according to the Markovian quantum master equation. As a result, it is shown that the intricate interplay between strong correlation and large electric field can generate a sequence of two dielectric breakdowns with the first induced by a coherent reconstruction of the midgap state within the Mott gap and the second by an incoherent tunneling through the biased Hubbard bands. It is predicted that the reconstructed midgap state generates its own emergent WSL structure with a reduced effective electric field. The two dielectric breakdowns are mediated by a reentrant insulating phase, which is characterized by the population inversion, causing instability toward inhomogeneous current density states at weak electron-impurity scattering.

Lee, Woo-Ram; Park, Kwon

2014-05-01

118

Impurity breakdown and terahertz luminescence in n-GaN epilayers under external electric field  

NASA Astrophysics Data System (ADS)

We report on the observation and experimental studies of impurity breakdown and terahertz luminescence in n-GaN epilayers under external electric field. The terahertz electroluminescence is observed in a wide range of doping levels (at noncompensated donor density from 4.5×1016 to 3.4×1018 cm-3). Spectra of terahertz luminescence and photoconductivity are studied by means of Fourier transform spectrometry. Distinctive features of the spectra can be assigned to intracenter electron transitions between excited and ground states of silicon and oxygen donors and to hot electron transitions to the donor states.

Shalygin, V. A.; Vorobjev, L. E.; Firsov, D. A.; Panevin, V. Yu.; Sofronov, A. N.; Melentyev, G. A.; Antonov, A. V.; Gavrilenko, V. I.; Andrianov, A. V.; Zakharyin, A. O.; Suihkonen, S.; Törma, P. T.; Ali, M.; Lipsanen, H.

2009-12-01

119

Discussion of Electrode Conditioning Mechanism Based on Pre-breakdown Current under Non-uniform Electric Field in Vacuum  

Microsoft Academic Search

Electrode conditioning is very important technique for improvement of the insulation performance of vacuum circuit breakers (VCBs). This paper discusses the spark conditioning mechanism under non-uniform electric field focused on the pre-breakdown current. We quantitatively evaluated the spark conditioning effect by analyzing the pre-breakdown current based on Fowler-Nordheim equation. As a result, field enhancement factor beta decreased with the increasing

Takanori Yasuoka; Tomohiro Kato; Katsumi Kato; Hitoshi Okubo

2008-01-01

120

Electrical measurements at the microscale: Air breakdown and silicon Coulomb blockade devices  

NASA Astrophysics Data System (ADS)

In this thesis I describe the work performed in two different areas of research, electrical breakdown of air for small electrode separations and measurements of silicon (Si)-based tunable-barrier single electron transistors (SETs). In this work, I describe a new method for measuring the breakdown of air for the range of electrode separation of interest. This method has several advantages compared to ones found in the literature, namely it allows for a measurement of electrode separation before each breakdown measurement; it has a parallel plate geometry and the surface roughness of the electrodes used is very small. Using the results obtained with this method I have made a quantitative comparison between the predictions of the standard theory of the field (field emission of electrons) and our data, something that has not been done before. In this thesis I describe analytically both the theory and the analysis of our data. I conclude that the standard theory used in this field fails for the range of electrode separations of interest (400 nm to 45 mum). Also, I describe electrical measurements performed on a Si-based tunable-barrier device fabricated in the group of Neil Zimmerman at the National Institute of Standards and Technology (NIST) using the fabrication facilities of Cornell University. I demonstrate that this device can be operated as an SET. I continue by describing measurements of the charge offset drift (Q 0(t)) for this device and show that it is almost 3 orders of magnitude smaller than in metal devices, and comparable to previously measured Si devices of this type. All of the previously measured devices originated from the same fabrication source, NTT, Japan. Our ability to demonstrate the same low drift in devices fabricated at Cornell, USA, indicates that the small values of Q0(t) is a robust property of Si-based devices, and not sensitive to the details of fabrication.

Hourdakis, Emmanouel Spyros

121

Electric-induced oxide breakdown of a charge-coupled device under femtosecond laser irradiation.  

PubMed

A femtosecond laser provides an ideal source to investigate the laser-induced damage of a charge-coupled device (CCD) owing to its thermal-free and localized damage properties. For conventional damage mechanisms in the nanosecond laser regime, a leakage current and degradation of a point spread function or modulation transfer function of the CCD are caused by the thermal damages to the oxide and adjacent electrodes. However, the damage mechanisms are quite different for a femtosecond laser. In this paper, an area CCD was subjected to Ti: sapphire laser irradiation at 800 nm by 100 fs single pulses. Electric-induced oxide breakdown is considered to be the primary mechanism to cause a leakage current, and the injured oxide is between the gate and source in the metal-oxide semiconductor field-effect transistor (MOSFET) structure for one CCD pixel. Optical microscopy and scanning electron microscopy are used to investigate the damaged areas and the results show that the electrodes and the oxide underneath are not directly affected by the femtosecond laser, which helps to get rid of the conventional damage mechanisms. For the primary damage mechanism, direct damage by hot carriers, anode hole injection, and an enlarged electric field in the insulating layer are three possible ways to cause oxide breakdown. The leakage current is proved by the decrease of the resistance of electrodes to the substrate. The output saturated images and the dynamics of an area CCD indicate that the leakage current is from an electrode to a light sensing area (or gate to source for a MOSFET), which proves the oxide breakdown mechanism. PMID:24216654

Gao, Liuzheng; Zhu, Zhiwu; Shao, Zhengzheng; Cheng, Xiang'ai; Chang, Shengli

2013-11-01

122

Electrical characteristics of anodic tantalum pentoxide thin films under thermal stress  

Microsoft Academic Search

In this work, we report on electrical characteristics of tantalum oxide films fabricated by anodic oxidation of tantalum nitride and tantalum silicide with thicknesses ranging from 100 to 4500 Å. These films exhibit greatly improved leakage currents, breakdown voltage and a very low defect density, thus allowing the fabrication of large area capacitors. Leakage currents in the insulator under thermal

S Dueñas; H Castán; J Barbolla; R. R Kola; P. A Sullivan

2000-01-01

123

Electric fields of a laser plasma formed by optical breakdown of air near various targets  

SciTech Connect

An experimental investigation was made of the spatiotemporal structure of the electric fields of a plasma formed as a result of optical breakdown of air near the target surface by radiations of various wavelengths (0.193, 0.53, 1.06, and 10.6 {mu}m), pulse durations (microsecond, nanosecond, and subnanosecond), and intensities (10{sup 8} - 10{sup 13} W cm{sup -2}). A study was made of the influence of the target and of nearby objects, and of their materials (conductor, dielectric) on the distribution of the electric fields of the laser plasma, and also on the probe diagnostic system. (interaction of laser radiation with matter. laser plasma)

Kabashin, A V; Nikitin, P I [A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Marine, W; Sentis, M L [Faculte des Sciences de Luminy, Universite de Aix-Marseille II (France)

1998-01-31

124

Electrical and optical characteristics of water under high electric stress  

Microsoft Academic Search

In order to determine the electrical characteristics of water under high electric stress, we have measured the current-electric field (I-E) characteristics of distilled water with a resistivity of 200 k?cm, up to electric field intensities of 1 MV\\/cm. The gap between a 1.7 mm diameter sphere and a plane stainless steel electrodes was varied between 50 ?m to 400 ?m.

S. Katsuki; R. P. Joshi; M. Laroussi; F. Leipold; K. H. Schoenbach

2002-01-01

125

A Review of Electrical Breakdown in Mixtures of SF6 and Other Gases  

Microsoft Academic Search

The outstanding electrical and arc-quenching characteristics of sulphur-hexafluoride (SF6) have already set new trends and standards for the construction of high voltage equipment. Intensive research is being carried out on the electrical properties of SF6, other electronegative gases and their mixtures with more common gases. The aims are to obtain an economical insulation with optimal electrical properties and to acquire

N. H. MIalikand; A. H. Qureshi

1979-01-01

126

Electrical breakdown of solid dielectrics and rocks on the trailing edge of a voltage pulse  

NASA Astrophysics Data System (ADS)

An analysis of modern notions of breakdown in condensed media opens up new possibilities for a decrease in the microsecond voltages for solid dielectric breakdown. Investigations of solid dielectric and rock breakdowns on the trailing edge of a voltage pulse in a sharply nonuniform field demonstrate that the pulse amplitude and the slope of the working voltage pulse edge can be decreased significantly.

Kuznetsov, Yu. I.; Vazhov, V. F.; Zhurkov, M. Yu.

2011-09-01

127

Selective removal of metallic single-walled carbon nanotubes in full length by organic film-assisted electrical breakdown.  

PubMed

An organic film-assisted electrical breakdown technique is proposed to selectively remove metallic (m-) single-walled carbon nanotubes (SWNTs) in full length towards creation of pure semiconducting SWNT arrays which are available for the large-scale fabrication of field effect transistors (FETs). The electrical breakdown of horizontally aligned SWNT arrays embedded in organic films resulted in a maximum removal length of 16.4 ?m. The removal of SWNTs was confirmed using scanning electron microscopy and Raman mapping measurements. The on/off ratios of FETs were improved up to ca. 10?000, similar to that achieved for in-air breakdown. The experimental results suggest that exothermic oxidation of organic films induces propagation of oxidation reaction, hence the long-length removal of m-SWNTs. PMID:24956406

Otsuka, Keigo; Inoue, Taiki; Chiashi, Shohei; Maruyama, Shigeo

2014-07-10

128

Streamer characteristic and breakdown in synthetic and natural ester transformer liquids with pressboard interface under lightning impulse voltage  

Microsoft Academic Search

This paper presents experimental studies on streamer and breakdown of synthetic and natural ester liquids with the presence of pressboard interface in a divergent point-plane field under lightning impulse voltage. Based on the current, light signals and streamer images, characteristics of both positive and negative streamers on pressboard surface were described, which resemble the features of streamers in open liquid

Q. Liu; Z. D. Wang

2011-01-01

129

The validity of the general similarity law for electrical breakdown of gases  

NASA Astrophysics Data System (ADS)

This paper investigates the validity of the similarity law in cases of dc and pulse breakdown of gases. Geometrically similar systems insulated with SF6 gas were used during experiments. It is shown that the similarity law is valid for dc breakdown voltage if the electron mean free path is included in geometrical parameters of the system, but not for pulse breakdown voltages. The explanation for this is the mechanism of the pulse discharge. The similarity law was expanded to take into account mechanisms of pulse breakdown initiation. Thus, the general similarity law is obtained, the validity of which in case of a pulse breakdown is established experimentally.

Osmokrovic, Predrag; Zivic, Tamara; Loncar, Boris; Vasic, Aleksandra

2006-11-01

130

Effects of void size and gas content on electrical breakdown in lightweight, mechanically compliant, void-filled dielectrics  

NASA Astrophysics Data System (ADS)

Dielectric potting materials (encapsulants) are used to prevent air breakdown in high-voltage electrical devices. We report breakdown strengths in void-filled encapsulants, stressed with unipolar voltage pulses of the order of 10 ?s duration. High strengths, on the order of 100 kV mm-1, are measured under these test conditions. The materials studied include low-density open celled gel-derived foams with cell sizes of 4 ?m or less, closed celled CO2-blown polystyrene and urethane foams, and epoxies containing 48 vol % of hollow glass microballoon (GMB) fillers. These last specimens varied the void gas (N2 or SO2) and also the void diameters (tens to hundreds of ?m). Our measurements are thought to be directly sensitive to the rate of field-induced ionization events in the void gas; however, the breakdown strengths of the materials tested appeared to vary in direct proportion with the conventional Paschen-law gas-discharge inception threshold, the electric stress at which gas-ionization avalanches become possible. The GMB-epoxy specimens displayed this type of dependence of breakdown strength on the void-gas density and void size, but the measurements were an order of magnitude above the conventional predictions. Small-celled foams also showed increased breakdown strengths with decreased cell size, although their irregular void geometry prevented a direct comparison with the more uniformly structured microballoon-filled encapsulants. The experimental observations are consistent with a breakdown mechanism in which the discharge of a few voids can launch a full breakdown in the composite material.

Anderson, R. A.; Lagasse, R. R.; Russick, E. M.; Schroeder, J. L.

2002-03-01

131

Improvement of breakdown characteristics of an AlGaN/GaN HEMT with a U-type gate foot for millimeter-wave power application  

NASA Astrophysics Data System (ADS)

In this study, the physics-based device simulation tool Silvaco ATLAS is used to characterize the electrical properties of an AlGaN/GaN high electron mobility transistor (HEMT) with a U-type gate foot. The U-gate AlGaN/GaN HEMT mainly features a gradually changed sidewall angle, which effectively mitigates the electric field in the channel, thus obtaining enhanced off-state breakdown characteristics. At the same time, only a small additional gate capacitance and decreased gate resistance ensure excellent RF characteristics for the U-gate device. U-gate AlGaN/GaN HEMTs are feasible through adjusting the etching conditions of an inductively coupled plasma system, without introducing any extra process steps. The simulation results are confirmed by experimental measurements. These features indicate that U-gate AlGaN/GaN HEMTs might be promising candidates for use in millimeter-wave power applications.

Kong, Xin; Wei, Ke; Liu, Guo-Guo; Liu, Xin-Yu

2012-12-01

132

Impact of the layout on the electrical characteristics of double-sided silicon 3D sensors fabricated at FBK  

NASA Astrophysics Data System (ADS)

We report on experimental results and TCAD simulations addressing the impact of layout on the electrical characteristics of double-sided 3D diodes fabricated at Fondazione Bruno Kessler (FBK), Trento, Italy. Simulations are found to accurately reproduce the device characteristics, thus explaining the basic mechanisms governing the breakdown behavior and capacitance of different devices and providing useful hints for layout optimization.

Povoli, M.; Bagolini, A.; Boscardin, M.; Dalla Betta, G.-F.; Giacomini, G.; Mattedi, F.; Vianello, E.; Zorzi, N.

2013-01-01

133

Chaos and hyperchaos in the electric avalanche breakdown of p-germanium at 4.2 K  

NASA Astrophysics Data System (ADS)

p-Ge electrically driven into the post-breakdown regime at 4.2 K produces spontaneous current oscillations. Under variation of the control parameter, namely the electric or magnetic field, we observed different routes to chaos, and a transition from a chaotic to a hyperchaotic state. Simultaneously, a loss of spatial coherence was found, indicating a break-up of the system in coupled subsystems. Phonons seem to be an important coupling mechanism between these subsystems.

Peinke, J.; Mühlbach, A.; Röhricht, B.; Wessely, B.; Mannhart, J.; Parisi, J.; Huebener, R. P.

1986-12-01

134

Electrical characteristics of simulated tornadoes  

NASA Astrophysics Data System (ADS)

It is well known that tornadoes and dust devils have the ability to accumulate significant, visible clouds of debris. Collisions between sand-like debris species produce different electric charges on different types of grains, which convect along different trajectories around the vortex. Thus, significant charge separations and electric currents are possible, which as the vortex fluctuates over time are thought to produce ULF radiation signatures that have been measured in the field. These electric and magnetic fields may contain valuable information about tornado structure and genesis, and may be critical in driving electrochemical processes within dust devils on Mars. In the present work, existing large eddy simulations of debris-laden tornadoes performed at West Virginia University are coupled with a new debris-charging and advection code developed at Goddard Space Flight Center to investigate the detailed (meter-resolution) fluid-dynamic origins of electromagnetic fields within terrestrial vortices. First results are presented, including simulations of the electric and magnetic fields that would be observed by a near-surface, instrument-laden probe during a direct encounter with a tornado. This research was supported by an appointment to the NASA Postdoctoral Program at the Goddard Space Flight Center, administered by Oak Ridge Associated Universities through a contract with NASA. The generous allocation of computing resources by Dr. Timothy J. Stubbs is gratefully acknowledged.

Zimmerman, M. I.; Farrell, W. M.; Barth, E. L.; Lewellen, D. C.; Lewellen, W. S.; Perlongo, N. J.; Jackson, T.

2012-12-01

135

Metallurgical analysis of electrical breakdown for CuTe system contact materials in vacuum  

Microsoft Academic Search

Cu-Te contact materials with different compositions and microstructures are investigated for their difference in breakdown field strength by connecting a 6-kV DC voltage source to a vacuum gap. The influence of Se, Te and Fe (which are doped during metallurgical processes) on breakdown behavior is discussed. It is found that when the number of breakdowns increase, the voltage stress of

C. Qiu; S. Wei; Z. Yang; J. Zhang; B. Ding; X. Wang

1992-01-01

136

Model Assessment of Cell Membrane Breakdown in Clusters and Tissues Under High-Intensity Electric Pulsing  

Microsoft Academic Search

This paper presents a simulation study of cell membrane electroporation in clusters by high-intensity voltage pulses. The focus is on assessing effects associated with: 1) the variability in shape and randomness of the cells within clusters; 2) the density of clusters; 3) the effects in heterogeneous tissues; 4) the role of pulse width on fractional electroporation for given electrical characteristics;

Ravindra P. Joshi; Ashutosh Mishra; Karl H. Schoenbach

2008-01-01

137

Breakdown of Liquid Dielectrics  

Microsoft Academic Search

A study was made of electrical breakdown of a liquid (hexachlorodiphenyl) the viscosity of which is very dependent on temperature. It is shown that in uniform fields breakdown results from formation and growth of a vapour bubble in the liquid. This was established by direct microscopic observations of the 'breakdown event' at room temperature and by measurements of times to

Z. Krasucki

1966-01-01

138

Characteristics of primary electric propulsion systems. [conferences  

NASA Technical Reports Server (NTRS)

The use of advanced electric propulsion systems is expected to provide cost and performance benefits for future energetic space missions. A methodology to predict the characteristics of advanced electric propulsion systems was developed and programmed for computer calculations to allow evaluation of a broad set of technology and mission assumptions. The impact on overall thrust system characteristics was assessed for variations of propellant type, total accelerating voltage, thruster area, specific impulse, and power system approach. The data may be used both to provide direction to technology emphasis and allow for preliminary estimates of electric propulsion system properties for a wide variety of applications.

Byers, D. C.

1979-01-01

139

Investigation of vibration characteristics of electric motors  

NASA Technical Reports Server (NTRS)

The vibration characteristics of electric motors were analyzed using mathematical statistics methods. The equipment used and the method of conducting the test are described. Curves are developed to show the visualization of the electric motor vibrations in the vertical direction. Additional curves are included to show the amplitude-phase frequency characteristic of dynamic rotor-housing vibrations at the first lug and the same data for the second lug of the electric motor. Mathematical models were created to show the transmission function of the dynamic rotor housing system.

Bakshis, A. K.; Tamoshyunas, Y. K.

1973-01-01

140

Investigation on critical breakdown electric field of hot sulfur hexafluoride/carbon tetrafluoride mixtures for high voltage circuit breaker applications  

NASA Astrophysics Data System (ADS)

Sulfur hexafluoride (SF6) gas, widely used in high-voltage circuit breakers, has a high global warming potential and hence substitutes are being sought. The use of a mixture of carbon tetrafluoride (CF4) and SF6 is examined here. It is known that this reduces the breakdown voltage at room temperature. However, the electrical breakdown in a circuit breaker after arc interruption occurs in a hot gas environment, with a complicated species composition because of the occurrence of dissociation and other reactions. The likelihood of breakdown depends on the electron interactions with all these species. The critical reduced electric field strength (the field at which breakdown can occur, relative to the number density) of hot SF6/CF4 mixtures corresponding to the dielectric recovery phase of a high voltage circuit breaker is calculated in the temperature range from 300 K to 3500 K. The equilibrium compositions of hot SF6/CF4 mixtures under different mixing fractions were determined based on Gibbs free energy minimization. Full sets of improved cross sections for interactions between electrons and the species present are presented. The critical reduced electric field strength of these mixtures was obtained by balancing electron generation and loss mechanisms. These were evaluated using the electron energy distribution function derived from the Boltzmann transport equation under the two-term approximation. The result indicates that critical electric field strength decreases with increasing heavy-particle temperature from 1500 to 3500 K. Good agreement was found between calculations for pure hot SF6 and pure hot CF4 and experimental results and previous calculations. The addition of CF4 to SF6 was found to increase the critical reduced electric field strength for temperatures above 1500 K, indicating the potential of replacing SF6 by SF6/CF4 mixtures in high-voltage circuit breakers.

Wang, Weizong; Murphy, Anthony B.; Rong, Mingzhe; Looe, Hui M.; Spencer, Joseph W.

2013-09-01

141

Wind tunnel investigation of the interaction and breakdown characteristics of slender wing vortices at subsonic, transonic, and supersonic speeds  

NASA Technical Reports Server (NTRS)

The vortex dominated aerodynamic characteristics of a generic 65 degree cropped delta wing model were studied in a wind tunnel at subsonic through supersonic speeds. The lee-side flow fields over the wing-alone configuration and the wing with leading edge extension (LEX) added were observed at M (infinity) equals 0.40 to 1.60 using a laser vapor screen technique. These results were correlated with surface streamline patterns, upper surface static pressure distributions, and six-component forces and moments. The wing-alone exhibited vortex breakdown and asymmetry of the breakdown location at the subsonic and transonic speeds. An earlier onset of vortex breakdown over the wing occurred at transonic speeds due to the interaction of the leading edge vortex with the normal shock wave. The development of a shock wave between the vortex and wing surface caused an early separation of the secondary boundary layer. With the LEX installed, wing vortex breakdown asymmetry did not occur up to the maximum angle of attack in the present test of 24 degrees. The favorable interaction of the LEX vortex with the wing flow field reduced the effects of shock waves on the wing primary and secondary vortical flows. The direct interaction of the wing and LEX vortex cores diminished with increasing Mach number. The maximum attainable vortex-induced pressure signatures were constrained by the vacuum pressure limit at the transonic and supersonic speeds.

Erickson, Gary E.

1991-01-01

142

Electrical breakdown strength of 5 kV XLPE cable with imperfections under combined AC-DC voltage  

Microsoft Academic Search

This paper presents data on electrical breakdown strength of 5 kV XLPE cable with imperfection under AC voltage, DC voltage and superimposed AC upon DC voltage (pulsate voltage). In the later case, the measurement was taken over a wide range of pulsate ratio, which is defined as p=Vac\\/Vdc. Comparison with the former measurement results for sound cables shows that the

S. Grzybowski; J. Fan

1996-01-01

143

New operating limits for applications with electroactive elastomer: effect of the drift of the dielectric permittivity and the electrical breakdown  

NASA Astrophysics Data System (ADS)

Dielectric elastomer generators are a promising solution to scavenge energy from human motion, due to their lightweight, high efficiency low cost and high energy density. Performances of a dielectric elastomer used in a generator application are generally evaluated by the maximum energy which can be converted. This energy is defined by an area of allowable states and delimited by different failure modes such as: electrical breakdown, loss of tension, mechanical rupture and electromechanical instability, which depend deeply on dielectric behaviors of the material. However, there is controversy on the dielectric constant (permittivity) of usual elastomers used for these applications. This paper aims to investigate the dielectric behaviors of two popular dielectric elastomers: VHB 4910 (3M) and Polypower (Danfoss). This study is undertaken on a broad range of temperature. We focus on the influence of pre-stretch in the change of the dielectric constant. An originality of this study is related to the significant influence of the nature of compliant electrodes deposited on these elastomers. Additionally, the electrical breakdown field of these two elastomers has been studied as a function of pre-stretch and temperature. Lastly, thanks to these experiments, analytic equations have been proposed to take into account the influence of the temperature, the pre-stretch and the nature of the compliant electrodes on the permittivity. These analytic equations and the electrical breakdown field were embedded in a thermodynamic model making it possible to define new limits of operation closer to the real use of these elastomers for energy harvesting applications.

Vu-Cong, T.; Jean-Mistral, C.; Sylvestre, A.

2013-04-01

144

The influence of the sand-dust environment on air-gap breakdown discharge characteristics of the plate-to-plate electrode  

NASA Astrophysics Data System (ADS)

The experiments of plane-plane gap discharge was carried out in an environment of artificial sandstorm. By comparing and analyzing the differences in gap breakdown voltage between the sand & dust environment and clean air, some problems were investigated, such as effects of wind speed and particle concentration on the breakdown voltage, differences of gap discharge characteristics between the dust & sand medium and the clean air medium. The results showed that compared with the clean air environment, the dust & sand environment had a decreased gap breakdown voltage. The longer the gap distance, the greater the voltage drop; the breakdown voltage decreased with the increase of particle concentration in flow. With the increase of wind speed, the breakdown voltage decreased at the beginning and rose afterwards. The results of the paper may helpful for further research regarding the unidentified flashover and external insulation characteristics of the HV power grid in the dust & sand environment.

He, Bo; Zhang, Gang; Chen, Bangfa; Gao, Naikui; Li, Yaozhong; Peng, Zongren; Jin, Haiyun

2010-03-01

145

Measurement of the electric breakdown strength of transformer oil in the sub-nanosecond regime  

Microsoft Academic Search

The dielectric strength of highly purified insulating transformer oil has been measured in the sub-nanosecond regime under single pulse and repetitive burst conditions. Single pulse breakdown fields have been measured to be 11 MV\\/cm. Repetitive bursts to 1 kHz reduce the threshold field value by a factor of two, with lower breakdown fields recorded at a 1.2 kHz repetition rate.

J. M. Lehr; F. J. Agee; R. Copeland; W. D. Prather

1998-01-01

146

Landau-Zener tunnelling in 2D periodic structures in the presence of a gauge field: II. Electric breakdown  

NASA Astrophysics Data System (ADS)

We analyse dynamics of a quantum particle in a square lattice in the Hall configuration beyond the single-band approximation. For vanishing gauge (magnetic) field this dynamics is defined by the inter-band Landau-Zener tunnelling, which is responsible for the phenomenon known as the electric breakdown. We show that in the presence of a gauge field this phenomenon is absent, at least, in its common sense. Instead, the Landau-Zener tunnelling leads to the appearance of a finite current which flows in the direction orthogonal to the vector of a potential (electric) field.

Maksimov, D. N.; Chesnokov, I. Yu; Makarov, D. V.; Kolovsky, A. R.

2013-07-01

147

Electrical Characteristics of an Alternating Current Plasma Igniter in Airflow  

NASA Astrophysics Data System (ADS)

The electrical characteristics of an alternating current (AC) plasma igniter were investigated for a working gas of air at atmospheric pressure. The discharge voltage and current were measured in air in both breakdown and stable combustion processes, respectively, and the current-zero phenomena, voltage-current (V-I) characteristics were studied for different working gas flow rates. The results indicated that the working gas between anode and cathode could be ionized to generate gas discharge when the voltage reached 8 kV, and the maximum current was 33.36 A. When the current came to zero, current-zero phenomena appeared with duration of 2 ?s. At the current-zero moment, dynamic resistance between electrodes became extremely high, and the maximum value could reach 445 k?, which was the main factor to restrain the current. With increasing working gas flow rates, the gradient of V-I characteristic curves was increased, as was the dynamic resistance. At a constant driven power, the discharge voltage increased.

Zhao, Bingbing; He, Liming; Du, Hongliang; Zhang, Hualei

2014-04-01

148

Streamer characteristic and breakdown in synthetic and natural ester transformer liquids under standard lightning impulse voltage  

Microsoft Academic Search

Interests on ester liquids as replacement of mineral oil in large power transformers are growing in recent years. This paper presents experimental studies on streamer and breakdown in synthetic and natural esters. Lightning impulse voltage was chosen when considering the practicality of standard tests of transformer industry. First, streamer length, velocity, shape and mode were analyzed based on optical images

Q. Liu; Z. D. Wang

2011-01-01

149

Electrical Characteristics of Resistance Welding Tools  

Microsoft Academic Search

Methods of measurement and calculation of resistance welding tools, particularly for the large group of nonstandard type portable welding guns, are contained in this paper. Electrical characteristics have considerable bearing on 1. Kilovolt-amperes at an installation. 2. Required secondary voltage of the welding transformer. 3. Efficiency of the tool. Timesaving means for either measurement or calculation provide accuracies well within

E. M. Callender

1947-01-01

150

Impurity-breakdown-induced current filamentation in a dipolar electric field  

NASA Astrophysics Data System (ADS)

Filamentary current flow has been investigated in an epitaxial n-type GaAs layer with two Ohmic point contacts. A scanning laser microscope technique has revealed two characteristic regimes of filamentary structure: a large-area filament typical at higher sample currents, and a bendable filament arising at low currents and becoming curved in perpendicular magnetic fields. Self-organization is supposed to be significant upon forming the bendable filament, whereas the large-area filamentary structure is predominantly formed by the electric field distribution due to the point contact geometry. Numerical simulations have been carried out in the second case, showing a good agreement with experimental results.

Novák, V.; Wimmer, C.; Prettl, W.

1995-09-01

151

Explanation for the oxide thickness dependence of breakdown characteristics of metal-oxide-semiconductor structures  

Microsoft Academic Search

Experimental evidence is presented showing that the thickness dependence observed for charge-to-breakdown measurements of very thin oxide layers in metal-oxide-semiconductor structures is correlated with that for the reduction in total generated microscopic defects necessary to induce destruction. These results are discussed in relationship to the formation of paths connecting some of these defects from the cathode to the anode at

D. J. DiMaria

1997-01-01

152

Breakdown properties of epoxy nanodielectric  

SciTech Connect

Recent developments in polymeric dielectric nanocomposites have shown that these novel materials can improve design of high voltage (hv) components and systems. Some of the improvements can be listed as reduction in size (compact hv systems), better reliability, high energy density, voltage endurance, and multifunctionality. Nanodielectric systems demonstrated specific improvements that have been published in the literature by different groups working with electrical insulation materials. In this paper we focus on the influence of in-situ synthesized titanium dioxide (TiO{sub 2}) nanoparticles on the dielectric breakdown characteristics of an epoxy-based nanocomposite system. The in-situ synthesis of the particles creates small nanoparticles on the order of 10 nm with narrow size distribution and uniform particle dispersion in the matrix. The breakdown strength of the nanocomposite was studied as a function of TiO{sub 2} concentration at cryogenic temperatures. It was observed that between 2 and 6wt% yields high breakdown values for the nanodielectric.

Tuncer, Enis [ORNL] [ORNL; Cantoni, Claudia [ORNL] [ORNL; More, Karren Leslie [ORNL] [ORNL; James, David Randy [ORNL] [ORNL; Polyzos, Georgios [ORNL] [ORNL; Sauers, Isidor [ORNL] [ORNL; Ellis, Alvin R [ORNL] [ORNL

2010-01-01

153

Effects of glass transition on the dielectric breakdown and electrical conduction in several biodegradable polymers  

Microsoft Academic Search

Results of the conductivity and breakdown strength measured for several biodegradable polymers are reported. At room temperature, poly-L-lactic acid (PLLA) and polyethylene terephthalate succinate (PETS) have relatively low conductivity values that are comparable to low density polyethylene (LDPE). However, when the fact that PLLA and PETS are in the glass state is taken into consideration, the conductivity values of PLLA

Makoto Matsushita; Yasumasa Maeno; Hiroki Kino; Shinjiro Fujita; Naoshi Hirai; Toshikatsu Tanaka; Yoshimichi Ohki; Y. Tajitsu; Masanori Kohtoh; Shigemitsu Okabe

2005-01-01

154

A Study of the Electrical Breakdown of Liquids by Means of the Electro-Optical Shutter  

Microsoft Academic Search

The static and the impulse breakdown of paraffin oil and xylol were investigated by means of the electro-optical shutter. To obtain satisfactory operation of the shutter it was found necessary to use a double shutter consisting of three crossed nicol prisms and two Kerr cells. Because of the liquids being only commercially pure and of the occluded air and moisture,

Harold W. Washburn

1933-01-01

155

On Preliminary Breakdown  

NASA Astrophysics Data System (ADS)

The preliminary breakdown phase of a negative cloud-to-ground lightning flash was observed in detail. Observations were made with a Photron SA1.1 high-speed video camera operating at 9,000 frames per second, fast optical sensors, a flat-plate electric field antenna covering the SLF to MF band, and VHF and UHF radio receivers with bandwidths of 20 MHz. Bright stepwise extensions of a negative leader were observed at an altitude of 8 km during the first few milliseconds of the flash, and were coincident with bipolar electric field pulses called 'characteristic pulses'. The 2-D step lengths of the preliminary processes were in excess of 100 meters, with some 2-D step lengths in excess of 200 meters. Smaller and shorter unipolar electric field pulses were superposed onto the bipolar electric field pulses, and were coincident with VHF and UHF radio pulses. After a few milliseconds, the emerging negative stepped leader system showed a marked decrease in luminosity, step length, and propagation velocity. Details of these events will be discussed, including the possibility that the preliminary breakdown phase consists not of a single developing lightning leader system, but of multiple smaller lightning leader systems that eventually join together into a single system.

Beasley, W. H.; Petersen, D.

2013-12-01

156

Modeling the Electrical Characteristics of the Global Electric Circuit  

NASA Astrophysics Data System (ADS)

Earth's global electric circuit (GEC) embodies the electrical pathways by which currents flow from electrified clouds to the ionosphere and return through fair weather regions to the earth's surface. To investigate this pathway, an analytic model based on others' previous work has been developed to produce global estimates of atmospheric currents, electric fields, and potential distributions of the GEC. The atmosphere between the ground and the ionosphere is composed of complex current sources and conductivity distributions. In the global electric circuit, lightning events act as current generators maintaining the potential difference between the earth and ionosphere. An analytic solution to Poisson's equation was applied to the GEC, allowing for a steady-state calculation of global distributions in potential, electric fields and currents for specified conductivity distributions and current sources. The global distribution of current sources provided on a monthly basis by a recently developed empirical model of Wilson currents. Analytic representations of global conductivities are implemented that include large-scale changes in the galactic cosmic ray flux. A novel numeric solver for Poisson's equation was also developed to enable analysis of more complex distributions of conductivity, i.e. cloud and aerosol effects. These models allow one to determine how different lightning and conductivity distributions impact the electrical characteristics of the GEC.

Lucas, G.; Lehto, E.; Baumgaertner, A. J.; Thayer, J. P.; Forbes, J. M.; Zhang, X.

2013-12-01

157

Electric field changes generated by the preliminary breakdown for the negative cloud-to-ground lightning flashes in Malaysia and Sweden  

NASA Astrophysics Data System (ADS)

We present the study of the electric field changes generated by the preliminary breakdown for negative cloud-to-ground lightning flashes in Malaysia and Sweden concerning the association of slow field changes associated in preliminary breakdown process. We examined the total of 1685 negative cloud-to-ground lightning flashes from the total of 39 thunderstorms by recording the slow electric field, fast electric field and narrowband radiation field at 3 and 30 MHz signals simultaneously. Our results show that there is a pre-starting time, i.e. the duration between the first preliminary breakdown pulse and slow field changes starting point, which is found to be after the first preliminary breakdown pulse. The pre-starting time has the arithmetic and geometric mean range from 1.4-6.47 and 1-3.36 ms, respectively. The mean values of pre-starting time in Malaysia are greater than the values observed in Sweden by more than a factor of 3. From the two data sets it shows that the slow field changes never start before the preliminary breakdown. Furthermore, the use of single-station electric fields measurement with high resolutions of 12 bits transient recorder with several nanosecond accuracy allow one to distinguish the slow field changes generated by preliminary breakdown, which preceded the negative first return stroke, between tens to hundreds of milliseconds of pre-return stroke duration.

Baharudin, Z. A.; Fernando, M.; Ahmad, Noor Azlinda; Mäkelä, J. S.; Rahman, Mahbubur; Cooray, Vernon

2012-08-01

158

Electrical conduction and dielectric breakdown in aluminum oxide insulators on silicon  

Microsoft Academic Search

Leakage currents and dielectric breakdown were studied in MIS capacitors of metal-aluminum oxide-silicon. The aluminum oxide was produced by thermally oxidizing AlN at 800-1160°C under dry O2 conditions. The AlN films were deposited by RF magnetron sputtering on p-type Si (100) substrates. Thermal oxidation produced Al 2O3 with a thickness and structure that depended on the process time and temperature.

James Kolodzey; Enam Ahmed Chowdhury; Thomas N. Adam; Guohua Qui; I. Rau; J. O. Olowolafe; J. S. Suehle; Yuan Chen

2000-01-01

159

Extrapolation of electrical breakdown currents from the laboratory to Space Station  

NASA Technical Reports Server (NTRS)

Recent experiments conducted in a plasma chamber at NASA/MSFC on anodized aluminum coatings representative of Space Station Freedom design show that if the aluminum used as a thermal control coating is biased more than 80 V negative with respect to the plasma, the anodization will experience dielectric breakdown. As the thin anodization layer creates a capacitive charge buildup, large currents are observed during the arc. How plasma generation at the arc site can support large currents and discharge the surface charge layer is investigated. The importance for Space Station Freedom is that currents similar to those observed in the laboratory can be observed on orbit.

Vaughn, Jason A.; Carruth, Melvin R., Jr.; Katz, Ira; Mandell, Myron J.; Jongeward, Gary A.

1992-01-01

160

On electric field induced breakdown of passive films and the mechanism of pitting corrosion  

SciTech Connect

Scanning tunneling microscopy reveals that microscopic roughness inherently exists at the smoothest of metal surfaces. Mathematical modeling indicates that the passive film on the concave region of the surface is subject to higher-than-average electrostatic pressure and is, therefore, a preferred site for passive film rupture and micro pit formation. The model includes the role of Cl{sup {minus}} ion in the breakdown; Cl{sup {minus}} increases the electrostatic pressure and/or reduces the compressive strength of the film. It follows that pit initiation could be a repeated breakdown-repair process that deepens the micro pit until it reaches a critical depth determined by the IR voltage. Thereafter, the pit bottom remains active due to its electrode potential being in the active region of the polarization curve. The pit mostly widens but also can grow upward, eventually penetrating the outer surface and causing a short circuit of the IR voltage, shift of the electrode potential into the passive region, and cessation of pit growth at the penetration or over the entire pit surface. Repetition of the above process leads to further penetrations to produce the lace-like pattern or, if complete cessation occurred, the reinitiation of the pit at a sharp concave site. Acidification and chloride ions promote the IR condition for pit growth.

Yuan Xu; Minghua Wang; Pickering, H.W. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Materials Science and Engineering

1993-12-01

161

Mass analysis of neutral particles and ions released during electrical breakdowns on spacecraft surfaces  

NASA Technical Reports Server (NTRS)

A specialized spectrometer was designed and developed to measure the mass and velocity distributions of neutral particles (molecules and molecular clusters) released from metal-backed Teflon and Kapton films. Promising results were obtained with an insulation breakdown initiation system based on a moveable contact touching the insulated surfaces. A variable energy, high voltage pulse is applied to the contact. The resulting surface damage sites can be made similar in size and shape to those produced by a high voltage electron beam system operating at similar discharge energies. The point discharge apparatus was used for final development of several high speed recording systems and for measurements of the composition of the materials given off by the discharge. Results with this apparatus show evolution of large amounts of fluorocarbon fragments from discharge through Teflon FEP, while discharges through Kapton produce mainly very light hydrocarbon fragments at masses below about 80 a.m.u.

Kendall, B. R. F.

1983-01-01

162

Discharge Characteristics of SF6 in a Non-Uniform Electric Field Under Repetitive Nanosecond Pulses  

NASA Astrophysics Data System (ADS)

The characteristics of high pressure sulphur hexafluoride (SF6) discharges in a highly non-uniform electric field under repetitive nanosecond pulses are investigated in this paper. The influencing factors on discharge process, such as gas pressure, pulse repetition frequency (PRF), and number of applied pulses, are analyzed. Experimental results show that the corona intensity weakens with the increase of gas pressure and strengthens with the increase of PRF or number of applied pulses. Spark discharge images suggest that a shorter and thicker discharge plasma channel will lead to a larger discharge current. The number of applied pulses to breakdown descends with the increase of PRF and ascends with the rise of gas pressure. The reduced electric field (E/p) decreases with the increase of PRF in all circumstances. The experimental results provide significant supplements to the dielectric characteristics of strongly electronegative gases under repetitive nanosecond pulses.

Ran, Huijuan; Wang, Lei; Wang, Jue; Wang, Tao; Yan, Ping

2014-05-01

163

Understanding the electrical characteristics of micromotors  

NASA Astrophysics Data System (ADS)

This paper presents a comprehensive list of issues related to the electrical characteristics of both electrostatic and electromagnetic micromotors and aims at understanding the behavior of the micromotor from the electrical standpoint. The paper takes the step-by-step approach by first presenting an overview of the laws of electrostatics and electromagnetism for micromachines, their applicability, features and limitations, and then progresses to independently analyze some of the important machine related quantities like electromotive torque, force-output, angular frequencies, supply conditions and requirements, for different types of electrostatic and electromagnetic micromotor constructions. A thorough study on the electric machine parameters that affect the performance of the micromotor need to be performed, since it would serve as a useful link in integrating the micromachine output performance with the fabrication process and challenges associated with it. Achieving such integration would then determine the optimized working condition for the micromotor. The main reason for this study is that although significant advancements have fostered the growth of micromotors in the recent past which has led to the establishment of the micromotor as quite a remarkable machine for powering micromechanical devices, and also as an industrial requirement for various applications, there has always been a concern about the optimal performance of the micromotor, since there is more than just one technology that is being incorporated to realize the micromotor. With fields ranging from surface engineering and chemistry to material science engineering exerting influence on the micromotor design, it becomes very important to completely comprehend the electrophysics of the micromachine that would in turn interact with the science of fabrication to result in the development of better micromotors with considerably less functional complexity.

Emadi, Ali; Irudayaraj, Sujay S.

2005-06-01

164

Comparative Evaluation Between DC and AC Breakdown Characteristic of Dielectric Insulating Materials in Liquid Nitrogen  

Microsoft Academic Search

Due to the existence of AC loss in superconducting materials when an alternating voltage is applied, high cryogenic costs are inevitable to operate superconducting devices in AC networks. Therefore applications of superconducting devices in DC electric power networks could be regarded as the optimum choice for superconducting devices, because superconductors show exactly zero resistance to a DC source. Recently, DC

J. K. Seong; I. J. Seo; J. S. Hwang; B. W. Lee

2012-01-01

165

Reverse breakdown characteristics in InGa(Al)P\\/InGaP p-i-n junctions  

Microsoft Academic Search

The avalanche breakdown behaviour of InGa(Al)P has been investigated by growing a series of pin diode structures covering the material range from InGaP to InAlP. The results show that reverse leakage currents are very low in this material system in keeping with the large band-gap until the onset of avalanche breakdown. Comparing the breakdown voltage (Vbd) with that of GaAs,

J. P. R. David; M. Hopkinson; R. Ghin; M. A. Pate

1994-01-01

166

Self-healing breakdown of polyimide thin films in the cryogenic temperature region  

Microsoft Academic Search

The breakdown characteristics of polyimide thin films were measured by taking advantage of self-healing breakdown in a wide temperature range. The electrical breakdown strength was nearly independent of temperature from 77 K to room temperature; it decreased with temperature in the high-temperature region. It showed little electrode-metal dependence at 77 K, but at room temperature, the A1 cathode indicated a

Y. Muramoto; M. Nagao; M. Kosaki

1995-01-01

167

An analysis of the initial breakdown pulse for positive cloud-to-ground flashes  

Microsoft Academic Search

In order to further understand the initiating mechanism of positive cloud-to-ground (PCG) flashes, the nature and temporal characteristics of the positive breakdown pulse trains are investigated by electric field data in Conghua of Guangdong province. Considering the difference between the initial polarity of initial breakdown pulses and the first return stoke (RS), three types of bipolar pulse trains, including the

Yang Zhang; YiJun Zhang; WeiTao Lu; Dong Zheng; Qing Meng

2011-01-01

168

The repetitive breakdown and flashover properties of solid dielectric materials under DC and pulsed conditions  

Microsoft Academic Search

This paper reports on the results of a test programme to investigate the material limits of solid dielectric insulation at potentials in excess of 100 kV. This comparative study of various materials was not an attempt to optimise the material breakdown voltage but to make a direct sample comparison under identical, representative pulsed power conditions. The electrical breakdown characteristics of

Andrew J McPhee; Scott J MacGregor; Jolyon R Tidmarsh

1996-01-01

169

Very Low Frequency Breakdown Properties of Electrical Insulation Materials at Cryogenic Temperatures  

NASA Astrophysics Data System (ADS)

For long cables or equipment with large capacitance it is not always possible to conduct high voltage withstand tests at 60 Hz due to limitations in charging currents of the power supply. Very low frequency (typically at a frequency of 0.1 Hz) has been used for conventional cables as a way of getting around the charging current limitation. For superconducting grid applications the same issues apply. However there is very little data at cryogenic temperatures on how materials perform at low frequency compared to 60 Hz and whether higher voltages should be applied when performing a high voltage acceptability test. Various materials including G10 (fiberglass reinforced plastic or FRP), Cryoflex™ (a tape insulation used in some high temperature superconducting cables), kapton (commonly used polyimide), polycarbonate, and polyetherimide, and in liquid nitrogen alone have been tested using a step method for frequencies of 60 Hz, 0.1 Hz, and dc. The dwell time at each step was chosen so that the aging factor would be the same in both the 60 Hz and 0.1 Hz tests. The data indicated that, while there is a small frequency dependence for liquid nitrogen, there are significant differences for the solid materials studied. Breakdown data for these materials and for model cables will be shown and discussed.

Sauers, I.; Tuncer, E.; Polizos, G.; James, D. R.; Ellis, A. R.; Pace, M. O.

2010-04-01

170

VERY LOW FREQUENCY BREAKDOWN PROPERTIES OF ELECTRICAL INSULATION MATERIALS AT CRYOGENIC TEMPERATURES  

SciTech Connect

For long cables or equipment with large capacitance it is not always possible to conduct high voltage withstand tests at 60 Hz due to limitations in charging currents of the power supply. Very low frequency (typically at a frequency of 0.1 Hz) has been used for conventional cables as a way of getting around the charging current limitation. For superconducting grid applications the same issues apply. However there is very little data at cryogenic temperatures on how materials perform at low frequency compared to 60 Hz and whether higher voltages should be applied when performing a high voltage acceptability test. Various materials including G10 (fiberglass reinforced plastic or FRP), Cryoflex (a tape insulation used in some high temperature superconducting cables), kapton (commonly used polyimide), polycarbonate, and polyetherimide, and in liquid nitrogen alone have been tested using a step method for frequencies of 60 Hz, 0.1 Hz, and dc. The dwell time at each step was chosen so that the aging factor would be the same in both the 60 Hz and 0.1 Hz tests. The data indicated that, while there is a small frequency dependence for liquid nitrogen, there are significant differences for the solid materials studied. Breakdown data for these materials and for model cables will be shown and discussed.

Sauers, I.; Tuncer, E.; Polizos, G.; James, D. R.; Ellis, A. R.; Pace, M. O. [Applied Superconductivity Group, Fusion Energy Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

2010-04-08

171

VERY LOW FREQUENCY BREAKDOWN PROPERTIES OF ELECTRICAL INSULATION MATERIALS AT CRYOGENIC TEMPERATURES  

SciTech Connect

For long cables or equipment with large capacitance it is not always possible to conduct high voltage withstand tests at 60 Hz due to limitations in charging currents of the power supply. Very low frequency (typically at a frequency of 0 1 Hz) has been used for conventional cables as a way of getting around the charging current limitation For superconducting grid applications the same issues apply. However there is very little data at cryogenic temperatures on how materials perform at low frequency compared to 60 Hz and whether higher voltages should be applied when performing a high voltage acceptability test. Various materials including G 10 (fiberglass reinforced plastic or FRP), Cryoflex (TM) (a tape insulation used in some high temperature superconducting cables), kapton (commonly used polyimide), polycarbonate, and polyetherimide, and in liquid nitrogen alone have been tested using a step method for frequencies of 60 Hz, 0.1 Hz, and dc The dwell time at each step was chosen so that the aging factor would be the same in both the 60 Hz and 0 I Hz tests. The data indicated that, while there is a small frequency dependence for liquid nitrogen, there are significant differences for the solid materials studied. Breakdown data for these materials and for model cables will be shown and discussed.

Sauers, I. [Oak Ridge National Laboratory (ORNL); Tuncer, E. [Oak Ridge National Laboratory (ORNL); Polizos, G. [Oak Ridge National Laboratory (ORNL); James, D. R. [Oak Ridge National Laboratory (ORNL); Ellis, A. R. [Oak Ridge National Laboratory (ORNL); Pace, M. O. [Oak Ridge National Laboratory (ORNL)

2010-01-01

172

VERY LOW FREQUENCY BREAKDOWN PROPERTIES OF ELECTRICAL INSULATION MATERIALS AT CRYOGENIC TEMPERATURES  

SciTech Connect

For long cables or equipment with large capacitance it is not always possible to conduct high voltage withstand at tests at 60 Hz due to limitations in charging currents of the power supply. Very low frequency (typically at a frequency of 0.1 Hz) has been used for conventional cables as a way of getting around the charging current limitation. For superconducting grid applications the same issues apply. However there is very little data at cryogenic temperatures on how materials perform at low frequency compared to 60 Hz and whether higher voltages should be applied when performing a high voltage acceptability test. Various materials including G10 (fiberglass reinforced plastic or FRP), Cryoflex (a tape insulation used in some high temperature superconducting cables), kapton (commonly used polyimide), polycarbonate, and polyetherimide, and in liquid nitrogen alone have been tested using a step method for frequencies of 60 Hz, 0.1 Hz, and dc. The dwell time at each step was chosen so that the aging factor would be the same in both the 60 Hz and 0.1 Hz tests. The data indicated that, while there is a small frequency dependence for liquid nitrogen, there are significant differences for the solid materials studied. Breakdown data for these materials and for model cables will be shown and discussed.

Sauers, Isidor [ORNL; Tuncer, Enis [ORNL; Polyzos, Georgios [ORNL; James, David Randy [ORNL; Ellis, Alvin R [ORNL; Pace, Marshall O [ORNL

2010-01-01

173

Effect of nano-fillers on electrical breakdown behavior of epoxy resin  

Microsoft Academic Search

Epoxy resin is widely used in high voltage apparatus as insulation due to its excellent mechanical, electrical and chemical properties. In recent years, researches on epoxy resin\\/nanocomposites have shown that the presence of nano-size filler in epoxy resin system can improve electrical, thermal and mechanical properties significantly. In the present paper, the epoxy resin containing nanosize SiO2 and Al2O3 fillers

Qi Wang; Peter Curtis; George Chen

2010-01-01

174

Electric field mediated breakdown of thin liquid films separating microscopic emulsion droplets  

NASA Astrophysics Data System (ADS)

The authors present a microfluidic technique for electrically induced breakup of thin films formed between microscopic emulsion droplets. The method involves creating a stationary film at the intersection of two microchannels etched onto a glass substrate. After stabilizing the film, a ramped potential is applied across it. The electrical stresses developed at the film interfaces lead to its rupture above a threshold potential. The potential difference at which the film ruptures assesses the film stability. This approach is employed to demonstrate how surfactant (lecithin) adsorption imparts stability to an ultrathin oil film formed between two water droplets.

Mostowfi, Farshid; Khristov, Khristo; Czarnecki, Jan; Masliyah, Jacob; Bhattacharjee, Subir

2007-04-01

175

Development of Numerical Methods to Estimate the Ohmic Breakdown Scenarios of a Tokamak  

NASA Astrophysics Data System (ADS)

The ohmic breakdown is a fundamental method to initiate the plasma in a tokamak. For the robust breakdown, ohmic breakdown scenarios have to be carefully designed by optimizing the magnetic field configurations to minimize the stray magnetic fields. This research focuses on development of numerical methods to estimate the ohmic breakdown scenarios by precise analysis of the magnetic field configurations. This is essential for the robust and optimal breakdown and start-up of fusion devices especially for ITER and its beyond equipped with low toroidal electric field (ET<=0.3 V/m). A field-line-following analysis code based on the Townsend avalanche theory and a particle simulation code are developed to analyze the breakdown characteristics of actual complex magnetic field configurations including the stray magnetic fields in tokamaks. They are applied to the ohmic breakdown scenarios of tokamaks such as KSTAR and VEST and compared with experiments.

Yoo, Min-Gu; Kim, Jayhyun; An, Younghwa; Hwang, Yong-Seok; Shim, Seung Bo; Lee, Hae June; Na, Yong-Su

2011-11-01

176

Effects of thermal and electrical stressing on the breakdown behavior of space wiring  

Microsoft Academic Search

Several failures in the electrical wiring systems of many aircraft and space vehicles have been attributed to arc tracking and damaged insulation. In some instances, these failures proved to be very costly as they have led to the loss of many aircraft and imperilment of space missions. Efforts are currently underway to develop lightweight, reliable, and arc track resistant wiring

Ahmad Hammoud; M. Staven; Jayant Suthar; Javaid Laghari

1995-01-01

177

Plasma characteristics determined by the Freja electric field instrument.  

National Technical Information Service (NTIS)

A new approach to the study of ionospheric plasma characteristics is presented using data from the Freja double probe electric field instrument. Plasma characteristics are derived from continuous measurements of the satellite potential and from intermitte...

P. A. Lindqvist G. T. Marklund L. G. Blomberg

1994-01-01

178

Tunneling characteristics of graphene  

Microsoft Academic Search

Negative differential conductance and tunneling characteristics of two-terminal graphene devices are observed before and after electric breakdown, respectively. The former is caused by the strong scattering under a high E-field, and the latter is due to the appearance of a tunneling barrier in graphene channel induced by a structural transformation from crystalline graphene to disordered graphene because of the breakdown.

Young Jun Shin; Gopinadhan Kalon; Jaesung Son; Jae Hyun Kwon; Jing Niu; Charanjit S. Bhatia; Gengchiau Liang; Hyunsoo Yang

2010-01-01

179

Projected characteristics of hybrid-electric cars  

Microsoft Academic Search

Performance and costs are projected for future hybrid-electric cars in which a small internal-combustion engine (ICE) is added to the basic electric propulsion system to permit unlimited highway range. In most driving these hybrids would be operated in the all-electric mode without use of the ICE, thus providing most of the benefits of electric cars without their range limitation. The

W. F. Hamilton; R. L. Curtis

1979-01-01

180

Statistical Analysis of Electrical Breakdown in a Micro Gap Using Weibull Distribution and Discussion on its Processes in High Voltage  

NASA Astrophysics Data System (ADS)

In this study, an experimental model is made on the basis of the Whitehead abc model and the properties of partial discharge (PD) breakdown in the micro gap are investigated. The quite unique properties of the PD breakdown in the micro gap are obtained: The voltage dependence of time to the PD breakdown and spread of residual negative charge distributions in the micro gap become discontinuous at a certain voltage amplitude. The discontinuousness in the PD breakdown properties is found to be due to the difference in surface discharge patterns in the micro gap: Polbüschel-type at lower voltage and Gleitbüschel-type at higher voltage. This paper aims at discussing the PD breakdown process at higher voltage. Time to the PD breakdown in the micro gap is analyzed using the Weibull probability distribution. The result suggests that the PD breakdown processes are classified into two different types: fatigue-failure-type and early/random-failure-type. Assuming that the PD breakdown of fatigue-failure-type is a thermally activated degradation process of Ahrenius type, the activation energy is caluculated . The value is in good accord with activation energy required for polymer bond scission caused by interaction with oxygen and ozone. The result suggests that the PD breakdown of fatigue-failure-type is caused by oxidative degradation. On the other hand, residual negative charges in the micro gap play an important role in the PD breakdown process of early/random-failure-type. In view of previous studies, it is possible that the PD breakdown process of early/random-failure-type is governed by the existing probability of structural defects where a great deal of the negative charges accumulates.

Imai, Kuniharu

181

Mechanical and Electrical Characteristics of Poly-Lactic Acid which Added Plasticizer  

NASA Astrophysics Data System (ADS)

Poly-lactic acid (PLA), a biodegradable plastic, has excellent electrical insulation properties. Being a hard resin, however, PLA is difficult to apply to coated cable. In this study, we blended a plasticizer with PLA to soften it, and examined the effects of the plasticizer on the mechanical and electrical characteristics of PLA. The glass transition temperature (Tg) and the melting point (Tm) had a tendency to decrease with an increase in the amount of plasticizer. With an increase in the amount of plasticizer, the tensile strength had a tendency to decrease and the breaking elongation to increase. As described above, PLA became softer with an increase in the amount of plasticizer. At 25°C, dielectric breakdown strength (EB) was about 5 MV/cm, irrespective of the presence of the plasticizer; the plasticizer showed almost no effect on EB. At 80°C, however, EB had a tendency to increase with an increase in the amount of plasticizer.

Shinyama, Katsuyoshi; Fujita, Shigetaka

182

Electrical properties of plasma-polymerized silicon-incorporated polyethylene films under very high electric fields  

Microsoft Academic Search

The current-voltage characteristics and the breakdown strengths of silicon-incorporated polyethylene films fabricated by plasma polymerization have been measured under very high electric fields using linear ramp voltages. The results show that electric conduction is mainly due to the flow of holes injected from the anode by a tunneling process, and that electric breakdown is initiated by thermal instability caused by

Dong Liu; Lin Kan; Kwan C. Kao

1991-01-01

183

Projected Characteristics of Hybrid-Electric Cars.  

National Technical Information Service (NTIS)

Performance and costs are projected for future hybrid-electric cars in which a small internal-combustion engine (ICE) is added to the basic electric propulsion system to permit unlimited highway range. In most driving these hybrids would be operated in th...

W. F. Hamilton R. L. Curtis

1979-01-01

184

Simple models for electric gun operating characteristics  

Microsoft Academic Search

The electric gun, sometimes called a foil gun, uses the energy initially stored in a capacitor to electrically heat a thin conducting bridge in a transmission line connected to the capacitor. The deposited energy, typically several times the cohesive energy of the bridge material, is deposited in a time much less than the thermal time constant of the bridge, causing

1988-01-01

185

Dielectric Breakdown in Media With Defects  

Microsoft Academic Search

We investigate the breakdown field and geometry of breakdown paths of an electrical circuit model for dielectric breakdown in media with defects of arbitrary residual resistivity. The circuit model consists of a two-dimensional square lattice network of resistors that break down from a high resistance to a lower (residual) resistance when the local electric field exceeds a critical value. We

Jeffrey Boksiner; P. L. Leath

1998-01-01

186

Electrical Insulation Characteristics of Glass Fiber Reinforced Resins  

SciTech Connect

Non-metallic structural materials that act as an electrical insulation are needed for cryogenic power applications. One of the extensively utilized materials is glass fiber reinforced resins (GFRR) and may also be known as GFRP and FRP. They are created from glass fiber cloth that are impregnated with an epoxy resin under pressure and heat. Although the materials based on GFRR have been employed extensively, reports about their dielectric properties at cryogenic temperatures and larger thicknesses are generally lacking in the literature. Therefore to guide electrical apparatus designers for cryogenic applications, GFRR samples with different thicknesses are tested in a liquid nitrogen bath. Scaling relation between the dielectric breakdown strength and the GFFR thickness is established. Their loss tangents are also reported at various frequencies.

Tuncer, Enis [ORNL; Sauers, Isidor [ORNL; James, David Randy [ORNL; Ellis, Alvin R [ORNL

2009-01-01

187

Phase characteristics of space charge signal under AC non-uniform electric field in PEA method  

Microsoft Academic Search

The treeing phenomena are well known as an initiation process of electrical breakdown in the electric power cables. It is discussed that the charge injection from electrode is related to the growth of the tree. The space charge measurement technique by the pulsed electro-acoustic (PEA) method is widely used. However, the measurement technique in the non-uniform electric field has not

Masumi Fukuma; Toru Takao; Masayuki Fujii

2011-01-01

188

Surface Temperature Measurement and Analysis of Thermal Breakdown with Ethylene-vinyl Acetate Copolymer in Room-Temperature Region  

Microsoft Academic Search

To understand the dc breakdown characteristics of an ethylene-vinyl acetate copolymer (EVA) film at room temperature, the temperature distribution of the film surface was observed by thermograph until electric breakdown occurred. The conduction current of the EVA film was also measured and correlated with the thermograph measurements. From the conduction current, the hopping distance was estimated as 2.1 nm. The

Yoshinobu Murakami; Naohiro Hozumi; Masayuki Nagao

2004-01-01

189

Electrode conditioning mechanism based on pre-breakdown current under non-uniform electric field in vacuum  

Microsoft Academic Search

Electrode conditioning in vacuum is very important technique for improvement of the insulation performance of vacuum circuit breakers (VCBs). This paper discusses the spark conditioning mechanism through the measurement and analysis of the pre-breakdown current under non-uniform field. From F-N plots, we made sure that the pre-breakdown current was based on field emission mechanism. We quantitatively evaluated the variation of

Hitoshi Okubo; Takanori Yasuoka; Tomohiro Kato; Katsumi Kato

2008-01-01

190

Electric propulsion - characteristics, applications, and status  

NASA Technical Reports Server (NTRS)

A comparative review of the principles of ion thruster and chemical rocket operations is presented. The 30cm mercury ion thruster development and the specifications imposed on it by the Solar Electric propulsion System program are discussed. The 30cm thruster operating range, efficiency, wear out lifetime, and interface requirements are described.

Maloy, J. E.; Dulgeroff, C. R.; Poeschel, R. L.

1981-01-01

191

Telecommunications: Electrical Characteristics of Balanced Voltage Digital Interface Circuits.  

National Technical Information Service (NTIS)

The standard specifies the electrical characteristics of balanced voltage digital interface circuits normally implemented in integrated circuit technology that are to be employed for the interchange of serial binary data, timing, and control signals betwe...

1980-01-01

192

Understanding the thermal, mechanical and electrical properties of epoxy nanocomposites  

Microsoft Academic Search

In the present work, the electrical, mechanical and thermal properties of epoxy nanocomposite materials were studied. The electrical insulation characteristics were analyzed through short time breakdown voltage test, accelerated electrical ageing test, and by tracking test. The breakdown voltage increases with increase in nano-clay content up to 5wt%, under AC and DC voltages. The volume resistivity, permittivity and tan(?) of

R. Sarathi; R. K. Sahu; P. Rajeshkumar

2007-01-01

193

The characteristic features of recovery of the breakdown strength of vacuum switching devices after interruption of high currents  

Microsoft Academic Search

The relevant effects determining the recovery period are discussed. Metal vapor and residual charge at early times after current extinction reduce the breakdown strength. Metal droplets play only a secondary role obviously. The drawing of liquid protrusion out of the molten contact surfaces will be a mechanism in case of high field strength at the contact surfaces. The knowledge about

E. Schade; E. Dullni

2000-01-01

194

Tin Whisker Electrical Short Circuit Characteristics. Part 2  

NASA Technical Reports Server (NTRS)

Existing risk simulations make the assumption that when a free tin whisker has bridged two adjacent exposed electrical conductors, the result is an electrical short circuit. This conservative assumption is made because shorting is a random event that has an unknown probability associated with it. Note however that due to contact resistance electrical shorts may not occur at lower voltage levels. In our first article we developed an empirical probability model for tin whisker shorting. In this paper, we develop a more comprehensive empirical model using a refined experiment with a larger sample size, in which we studied the effect of varying voltage on the breakdown of the contact resistance which leads to a short circuit. From the resulting data we estimated the probability distribution of an electrical short, as a function of voltage. In addition, the unexpected polycrystalline structure seen in the focused ion beam (FIB) cross section in the first experiment was confirmed in this experiment using transmission electron microscopy (TEM). The FIB was also used to cross section two card guides to facilitate the measurement of the grain size of each card guide's tin plating to determine its finish.

Courey, Karim J.; Asfour, Shihab S.; Onar, Arzu; Bayliss, Jon A.; Ludwig, Lawrence L.; Wright, Maria C.

2009-01-01

195

Mineralogical characteristics of electric arc furnace dusts  

NASA Astrophysics Data System (ADS)

Reflected light microscopy can contribute important information regarding the mineralogy, mineral abundance, internal textures, sizes and shapes of particles in electric arc furnace (EAF) dusts. Scanning electron microscopy-energy dispersive spectroscopy and electron microprobe analysis are useful to determine the chemical compositions of the specific mineral grains in the dust particles. Furthermore, the mineralogical reactions that have taken place during the pyro-metallurgical treatment of EAF dusts and the mineralogy and textural character of those treated dust samples can be directly observed by reflected light microscopy. Such studies are useful in monitoring the efficiency of experimental pyrometallurgical treatment of EAF dusts which are designed to render them nonhazardous.

Hagni, Ann M.; Hagni, Richard D.; Demars, Christelle

1991-04-01

196

Measuring Breakdown Voltage.  

ERIC Educational Resources Information Center

The article discusses an aspect of conductivity, one of the electrical properties subdivisions, and describes a tester that can be shop-built. Breakdown voltage of an insulation material is specifically examined. Test procedures, parts lists, diagrams, and test data form are included. (MF)

Auer, Herbert J.

1978-01-01

197

Flicker characteristic estimation of an AC electric arc furnace  

Microsoft Academic Search

This paper describes the estimation of the stochastic flicker characteristics for an electric arc furnace (EAF) over a complete heat. These characteristics include stationarity, normality and correlation. Besides, the basic statistical probability were assessed by varying sampling period, too. The estimation and the assessment were implemented by a microcomputer-based instrumentation system. The test results for a typical AC arc furnace

Chen-Wen Lu; Shyh-Jier Huang; Ching-Lien Huang

2000-01-01

198

An improvement in electrical characteristics of a short backfire antenna  

Microsoft Academic Search

A short backfire (SBF) antenna is considered to be a favorable option for a compact and high efficiency shipboard antenna in maritine satellite communications. Though the SBF antenna has many attractive characteristics, it has a demerit of narrow frequency bandwidths because of its leaky cavity operation in principle. The electrical characteristics of a conventional SBF antenna have been improved by

S. Ohmori; S. Miura; K. Kameyama; H. Yoshimura

1983-01-01

199

Mounting method improves electrical and vibrational characteristics of screen electrodes  

NASA Technical Reports Server (NTRS)

Electrical characteristics of the mesh or screen electrodes used in electron tubes are improved by decreasing the shunt capacitance of the tube while retaining the close spacing needed for the required resolution. Vibrational characteristics are enhanced by raising the natural resonant frequency.

Nelson, R. E.

1969-01-01

200

METHODOLOGICAL NOTES: Electric field strength of charged conducting balls and the breakdown of the air gap between them  

NASA Astrophysics Data System (ADS)

Field amplification factors at the surfaces of two charged conducting balls are calculated numerically. It is shown that as the balls are brought closer together, except when their potentials are equal, the amplification factors go to infinity, and in the case of like-charged balls the field at the surface of one of them changes sign. Breakdown field strengths for the air gap between balls of a different diameter are calculated using the experimental data of other authors as the base. The results suggest that the minimum breakdown field strength is 26 kV cm-1 . The author's earlier results on the interaction force between the balls are revised.

Saranin, Vladimir A.

2002-12-01

201

Gas breakdown driven by L band short-pulse high-power microwave  

SciTech Connect

High power microwave (HPM) driven gas breakdown is a major factor in limiting the radiation and transmission of HPM. A method that HPM driven gas breakdown could be obtained by changing the aperture of horn antenna is studied in this paper. Changing the effective aperture of horn antenna can adjust the electric field in near field zone, leading to gas breakdown. With this method, measurements of air and SF{sub 6} breakdowns are carried out on a magnetically insulated transmission-line oscillators, which is capable of generating HPM with pulse duration of 30 ns, and frequency of 1.74 GHz. The typical breakdown waveforms of air and SF{sub 6} are presented. Besides, the breakdown field strengths of the two gases are derived at different pressures. It is found that the effects of air and SF{sub 6} breakdown on the transmission of HPM are different: air breakdown mainly shortens the pulse width of HPM while SF{sub 6} breakdown mainly reduces the peak output power of HPM. The electric field threshold of SF{sub 6} is about 2.4 times larger than that of air. These differences suggest that gas properties have a great effect on the transmission characteristic of HPM in gases.

Yang Yiming; Yuan Chengwei; Qian Baoliang [College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073 (China)

2012-12-15

202

Gas breakdown driven by L band short-pulse high-power microwave  

NASA Astrophysics Data System (ADS)

High power microwave (HPM) driven gas breakdown is a major factor in limiting the radiation and transmission of HPM. A method that HPM driven gas breakdown could be obtained by changing the aperture of horn antenna is studied in this paper. Changing the effective aperture of horn antenna can adjust the electric field in near field zone, leading to gas breakdown. With this method, measurements of air and SF6 breakdowns are carried out on a magnetically insulated transmission-line oscillators, which is capable of generating HPM with pulse duration of 30 ns, and frequency of 1.74 GHz. The typical breakdown waveforms of air and SF6 are presented. Besides, the breakdown field strengths of the two gases are derived at different pressures. It is found that the effects of air and SF6 breakdown on the transmission of HPM are different: air breakdown mainly shortens the pulse width of HPM while SF6 breakdown mainly reduces the peak output power of HPM. The electric field threshold of SF6 is about 2.4 times larger than that of air. These differences suggest that gas properties have a great effect on the transmission characteristic of HPM in gases.

Yang, Yi-Ming; Yuan, Cheng-Wei; Qian, Bao-Liang

2012-12-01

203

Analytical model of the electrical characteristics of linear MHD generators  

NASA Astrophysics Data System (ADS)

A two-dimensional electrical model of multi-electrode linear generators is presented. The electrode-wall boundary layers are included in the treatment, and an allowance can be made for the effects of electrode arcs and slag layers. The external electrical properties of the MHD channel flow are defined by a set of four resistance matrices. Analytical expressions for the matrix elements are given. The formulation allows a rapid, straightforward determination of a generator's electrical characteristics and is suitable for analyzing the electrical nonuniformities often observed in slagging channels.

Simpson, S. W.

1983-12-01

204

Breakdown testing of wiring insulation  

NASA Technical Reports Server (NTRS)

The dielectric strength of potential wiring insulation, recommended by NASA Lewis Research Center to replace existing M81381 (polyimide), was evaluated at high temperature. Results, given in view-graph format, show that their is no dependence of breakdown strength on temperature for the constructions tested and that their was little effect of frequency on the breakdown characteristics.

Laghari, Javaid R.

1994-01-01

205

On the structure, interaction, and breakdown characteristics of slender wing vortices at subsonic, transonic, and supersonic speeds  

NASA Technical Reports Server (NTRS)

Slender wing vortex flows at subsonic, transonic, and supersonic speeds were investigated in a 6 x 6 ft wind tunnel. Test data obtained include off-body and surface flow visualizations, wing upper surface static pressure distributions, and six-component forces and moments. The results reveal the transition from the low-speed classical vortex regime to the transonic regime, beginning at a freestream Mach number of 0.60, where vortices coexist with shock waves. It is shown that the onset of core breakdown and the progression of core breakdown with the angle of attack were sensitive to the Mach number, and that the shock effects at transonic speeds were reduced by the interaction of the wing and the lead-edge extension (LEX) vortices. The vortex strengths and direct interaction of the wing and LEX cores (cores wrapping around each other) were found to diminish at transonic and supersonic speeds.

Erickson, Gary E.; Schreiner, John A.; Rogers, Lawrence W.

1989-01-01

206

Microwave breakdown in resonators and filters  

Microsoft Academic Search

Several aspects of microwave breakdown in resonators are discussed in this paper. Approximate analytical criteria are formulated for the critical microwave breakdown field in some illustrative model geometries, which clearly brings out the main physical properties of microwave-induced breakdown in the presence of inhomogeneous electric fields. The analytical results are verified by comparisons with numerical calculations. A full numerical solution

D. Anderson; U. Jordon; M. Lisak; T. Olsson; M. Ahlander

1999-01-01

207

Electrical properties and humidity sensor characteristics of lead hydroxyapatite material  

NASA Astrophysics Data System (ADS)

Crystalline lead hydroxyapatite is obtained by direct precipitation from aqueous solution, the method being easy, fast and reproducible. The synthesis route which does not involve sodium salts or sulfates makes the material suitable for applications in catalysis. The electrical characteristics of lead hydroxyapatite material treated at different temperatures, made us focus on the analysis of the influence of water vapors upon the electrical characteristics. Thus, the electrical response to humidity adsorptive processes of lead hydroxyapatite material suggested us to analyze the material characteristics in terms of its use as a humidity sensor. The hydrophilic properties of lead hydroxyapatite material are reflected especially in high sensitivity and reduced time of response of the humidity sensors but also in long time of recovery, which suggests that Pb10(PO4)6(OH)2 material can be used for humidity sensors specialized in monitoring fluctuating humidity environments.

Tudorache, Florin; Petrila, Iulian; Popa, Karin; Catargiu, Ana Maria

2014-06-01

208

Local electrical characteristics of dielectrophoretically deposited carbon nanotubes.  

PubMed

Electrostatic force microscopy and scanning gate microscopy are employed to investigate the local electrical characteristics of single-walled carbon nanotube (SWCNT) devices that are fabricated by alternating current dielectrophoresis with high spatial resolutions. The results show good electrical anchoring of nanotubes to electrodes and absence of local gate dependence as well as global gate dependence while device resistance can be dominated by contact resistances among bundles of SWCNTs. PMID:21456293

Jeong, Huiseong; Kang, Hosung; Baik, Seunghyun; Park, Ji-Yong

2011-02-01

209

A dynamic model for the electrical characteristics of fluorescent lamps  

Microsoft Academic Search

A model for the electrical behavior of fluorescent lamps at standard line frequency (50 Hz or 60 Hz) and at high frequency (20 kHz-50 kHz). The model is based on the following three relationships: the lamp's V-I characteristic at high frequency; the lamp's DC V-I characteristic; and the dynamic relationship between these two modes of operation. The first two are

U. Mader; P. Horn

1992-01-01

210

Electrical characteristics of the ITO\\/HgInTe photodiodes  

Microsoft Academic Search

Photodiodes designed to be sensitive in the region 0.5–1.7 m and obtained by vacuum magnetron sputtering of the ITO (SnO2 + In2O3) layer on the surface of the Hg3In2Te6 single crystal are studied. The electrical characteristics, measured at 265–333 K, indicate that the mechanism of charge\\u000a transport in the diodes under study is thermionic. The current-voltage characteristic and its temperature

L. A. Kosyachenko; I. M. Rarenko; E. F. Sklyarchuk; I. I. German; Sun Weiguo

2006-01-01

211

Electrical Energy Density and Discharge Characteristics of a Poly(vinylidene fluoride-chlorotrifluoroethylene)Copolymer  

Microsoft Academic Search

The high electric displacement (D>0.1 C\\/m2) and breakdown field (600 MV\\/m) in polyvinylidene fluoride based polymers suggest high electrical energy density in this class of polymers. By defect modifications which reduce or eliminate the remnant polarization in the polymer, a high electrical energy density can indeed be obtained. This paper shows that in properly prepared P(VDF-CTFE) copolymer film capacitors, an

Xin Zhou; Baojin Chu; Bret Neese; Minren Lin; Q. M. Zhang

2007-01-01

212

Analysis of thermal breakdown process with EVA film in room temperature region  

Microsoft Academic Search

In order to understand dc breakdown characteristics of ethylene-vinyl acetate copolymer (EVA) film at the room temperature, temperature distribution of film surface until the electric breakdown was observed by thermograph. Conduction current of EVA film was also measured and correlated with the thermograph. From the conduction current, hopping distance was estimated as 2.1×10-9 [m]. The potential barrier was calculated as

Y. Murakami; N. Hozumi; M. Nagao; S. Mitsumoto; M. Fukuma

2003-01-01

213

On the electrical characteristics of complementary metamaterial resonators  

Microsoft Academic Search

In this letter, a method to obtain the electrical characteristics of complementary split ring resonators (CSRRs) coupled to planar transmission lines is presented. CSRRs have been recently proposed by some of the authors as new constitutive elements for the synthesis of metamaterials with negative effective permittivity, and they have been applied to the fabrication of metamaterial-based circuits in planar technology.

Jordi Bonache; Marta Gil; Ignacio Gil; Joan García-García; Ferran Martín

2006-01-01

214

Determining the mode of high voltage breakdowns in vacuum devices  

Microsoft Academic Search

Vacuum diodes equipped with windows allowing observation of high voltage breakdowns were constructed. The waveform of the applied voltage was photographed, and the X-ray output was monitored to investigate electrical breakdown in these vacuum diodes. Breakdowns may be divided into types: (1) vacuum (interelectrode) breakdown - characterized by a diffuse moderately bright discharge, a relative slow and smooth voltage collapse,

H. C. Miller; E. J. Furno; J. P. Sturtz

1980-01-01

215

Gas Breakdown of Radio Frequency Glow Discharges in Helium at near Atmospheric Pressure  

NASA Astrophysics Data System (ADS)

A one-dimensional self-consistent fluid model was developed for radio frequency glow discharge in helium at near atmospheric pressure, and was employed to study the gas breakdown characteristics in terms of breakdown voltage. The effective secondary electron emission coefficient and the effective electric field for ions were demonstrated to be important for determining the breakdown voltage of radio frequency glow discharge at near atmospheric pressure. The constant of A was estimated to be 64±4 cm-1Torr-1, which was proportional to the first Townsend coefficient and could be employed to evaluate the gas breakdown voltage. The reduction in the breakdown voltage of radio frequency glow discharge with excitation frequency was studied and attributed to the electron trapping effect in the discharge gap.

Liu, Xinkun; Xu, Jinzhou; Cui, Tongfei; Guo, Ying; Zhang, Jing; Shi, Jianjun

2013-07-01

216

Basic Studies on Chaotic Characteristics of Electric Power Market Price  

NASA Astrophysics Data System (ADS)

Recently, deregulation and reform of electric power utilities have been progressing in many parts of the world. In Japan, partial deregulation has been started from generation sector since 1995 and partial deregulation of retail sector is executed through twice law revisions. Through the deregulation, because electric power is traded in the market and its price is always fluctuated, it is important for the electric power business to analyze and predict the price. Although the price data of the electric power market is time series data, it is not always proper to analyze by the linear model such as ARMA because the price sometimes changes suddenly. Therefore, in this paper, we apply the methods of chaotic time series analysis, one of non-linear analysis methods, and investigate the chaotic characteristics of the system price of JEPX.

Takeuchi, Yuya; Miyauchi, Hajime; Kita, Toshihiro

217

Progressive breakdown dynamics and entropy production in ultrathin SiO2 gate oxides  

NASA Astrophysics Data System (ADS)

The progressive breakdown of ultrathin (~2nm) SiO2 gate oxides subjected to constant electrical stress is investigated using a simple equivalent circuit model. It is shown how the interplay among series, parallel, and filamentary conductances that represent the breakdown path and its surroundings leads under certain hypothesis to a sigmoidal current-time characteristic compatible with the experimental observations. The dynamical properties of the breakdown trajectories are analyzed in terms of the logistic potential function, the Lyapunov exponent, and the system's attractor. It is also shown that the current evolution is compatible with Prigogine's minimum entropy production principle.

Miranda, E.; Jiménez, D.; Suñé, J.

2011-06-01

218

Morphological characteristics of tissue damages from electrical contact.  

PubMed

The purpose of the study was to reveal the morphological pattern of different tissues mostly vulnerable to electric contact injury from domestic electrical appliances and to determine the possible diagnostic criteria of this damage. The matter is of particular importance as domestic electrical appliances are widely used in torture and other cruel, inhuman and degrading treatment or punishment. The pilot part of the study was experimental and as the material of study have been used adult Wistar white rats. The microscopic study of slides taken from tissues damaged by electricity and dyed by routine Hematoxilin-Eosin reveals general structural changes that does not represent characteristic morphological pattern sufficient for forensic diagnosis of electric injury. The electricity damage of kidney and adrenal glands reflects the morphological pattern of stress that allows complex evaluation of damage but could have only orientating value for the estimation of cause of injury. Due to results obtained from pilot part of the study there is considered in regard to determine the possible diagnostic criteria for electrical injury of tissues the experimental morphological study must continue on skin and myocardial material using routine Hematoxilin-Eosin as well as other classical and modern morphological methods of study. PMID:19556650

Grigolia, D; Beriashvili, R; Kilasonia, B

2009-05-01

219

A possible new mechanism involved in non-uniform field breakdown in gaseous dielectrics  

SciTech Connect

The electrical breakdown of gases under uniform field conditions is fairly well understood in terms of the Townsend`s breakdown theory. In most cases involving uniform fields, the breakdown voltage can be estimated via this theory using basic electron impact parameters for molecules in their ground electronic states. In contrast, a consistent model of gaseous breakdown under nonuniform fields is not available at present although substantial progress has been made recently. We point out the possibility that electron impact processes involving high-lying electronically-excited states may play a significant role under non-uniform field conditions. Thus, such processes may need to be included in order to obtain a better understanding of non-uniform field breakdown phenomena. The general, breakdown characteristics of highly non-uniform field gaps can be illustrated by that for a point-plane geometry. It has been found that the breakdown voltage for such a gap can be calculated by a simple streamer criterion if the pressure P, is above a critical value, P{sub c}; for P < P{sub c}, the estimated breakdown voltage is found to coincide with the corona inception voltage, with the actual breakdown occurring at a higher voltage, corona discharges occur only for P < P{sub c}. In other words, the presence of corona in the pressure region below P{sub c} seems to prevent the breakdown from occurring at the predicted value. This has led to the term ``corona stabilization`` to describe the enhancement in the breakdown voltage for pressures below P{sub c}. Non-uniform field breakdown measurements in gases will be discussed. We will discuss the possibility that the ``corona stabilization`` is due to the prevention of avalanche progression by attachment of free electrons to molecules in their high-lying electronically-excited states. Information on electron attachment to electronically-excited states of molecules was not available up until the late 1980`s.

Pinnaduwage, L.A.; Christophorou, L.G.

1994-06-01

220

Electrical characteristics of a probe in a subsonic plasma flow  

NASA Astrophysics Data System (ADS)

The method of external and internal asymptotic small-parameter expansions is used to investigate the distribution of charged-particle densities and electric field in a slightly ionized plasma flowing past a conducting body (an electric probe) at high Reynolds numbers of the flow. The form of the volt-ampere characteristics of the probe is analyzed as a function of the values of the governing parameters of the problem. The theoretical results are verified by experimental data for the case of a cold probe in the flow of an air plasma with a potassium addition.

Benilov, M. S.; Bochkarev, G. G.; Buznikov, A. E.; German, V. O.; Kovbasiuk, V. I.

1983-02-01

221

Electrical characteristics of asymmetrical silicon nanowire field-effect transistors  

NASA Astrophysics Data System (ADS)

This letter reports the electrical characteristics of nonuniform silicon nanowire nFETs with asymmetric source and drain widths. For electrostatic properties, reduced drain-induced barrier lowering (DIBL) is achieved in a device in which the source is wider than the drain. For carrier transport properties, higher values of surface-roughness-limited mobility (?SR) are obtained in the sample with the wider drain size. Our electrostatic model shows that the concentration of lines of electric force is relaxed near the wider source edge, which results in smaller DIBL. The asymmetric ?SR is attributed to the channel surface morphology with (110)- and (100)-faceted surfaces.

Sato, Soshi; Kakushima, Kuniyuki; Ohmori, Kenji; Natori, Kenji; Yamada, Keisaku; Iwai, Hiroshi

2011-11-01

222

Electric discharge in the water: physics of formation and radiative characteristics.  

NASA Astrophysics Data System (ADS)

ELECTRIC DISCHARGE IN THE WATER: PHYSICS OF FORMATION AND RADIATIVE CHARACTERISTICS 2.10. Lighting plasmas. 2.26. Other plasma topics. A.M.Anpilov, E.M.Barkhudarov, Yu.N.Kozlov, I.A.Kossyi, V.P.Silakov and S.M.Temchin Two types of electric discharge in the water have been investigated: discharge between two electrodes and multielectrode gliding surface discharge. Results are presented from experimental studies of the prebreakdown phase of an electric discharge between the point (anode) and plane (cathode) electrodes immersed in the water with different initial conductivity. When a high-voltage pulse is applied, the induced conductivity is detected in the discharge gap. Its value is one order of magnitude higher than the initial one. It is shown that the induced conductivity increases almost linearly with initial conductivity. The induced conductivity correlates with the UV emission from the cathode surface. A qualitative analysis of the experimental results is performed. Investigations of a spectrum of radiation of discharge in water have been carried out. On the base of broadening and shifting of atomic hydrogen and oxygen lines electron density in a prebreakdown as well as breakdown stages has been determined. Results are presented from investigations of multispark electric discharge in water excited along multielectrode metal-dielectric systems with gas supply into the interelectrode gaps. The intensity distribution of discharge radiation in the region covering the biologically active soft UV (190 £l£430 nm) has been determined and the absolute number of quanta in this wavelength interval has been measured. The potentiality of the gliding surface discharge in water for its disinfection is analysed.

Anpilov, Andrei; Barkhudarov, Eduard; Kozlov, Yurii; Kossyi, Igor; Silakov, Valerii; Temchin, Savelii

2004-09-01

223

Low-temperature (77-300 K) current-voltage characteristics of 4H-SiC p{sup +}-p-n{sup +} diodes: Effect of impurity breakdown in the p-type base  

SciTech Connect

The effect of impurity breakdown on the low-temperature (77-300 K) current-voltage (I-V) characteristics of 4H-SiC diodes with a p-type base has been studied. Experimental samples were fabricated from CVD-grown (chemical vapor deposition) commercial p{sup +}-p-n{sup +} 4H-SiC structures. A high electric field in the p-type base was created by applying a forward bias to the diodes. It was found that, at temperatures of 136, 89, and 81 K, the commonly observed 'diode' portion of the I-V characteristics is followed by a portion in which the current grows more rapidly due to the impact ionization of frozen-out Al acceptor atoms in the ground (unexcited) state. At temperatures of 81 and 77 K, this portion is followed by one with a negative differential resistance due to the regenerative dynistor-like switching of the diode, caused by impact ionization of aluminum atoms in the excited state.

Ivanov, P. A., E-mail: Pavel.Ivanov@mail.ioffe.ru; Potapov, A. S.; Samsonova, T. P. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation)

2012-04-15

224

Electrical characteristics of interconnections for high-performance systems  

Microsoft Academic Search

A review is presented of the electrical characteristics of high-density, high-performance interconnections used in digital and communication applications. These interconnections behave as lossy transmission lines for the frequency range of interest. A brief theoretical explanation of the key properties of lossy, coupled transmission lines is given. A new short-pulse propagation technique used for characterizing a large category of wiring is

ALINA DEUTSCH

1998-01-01

225

High-resolution measurements of the electric field at the streamer arrival to the cathode: a unification of the streamer-initiated gas-breakdown mechanism.  

PubMed

A time-correlated single-photon counting technique was used to verify the formation of a cathode-directed streamer inside the narrow cathode region following the interpulse phase of regular negative corona Trichel pulses in ambient air. A purely experimental approach was used to determine the spatiotemporal development of the electric field during the Trichel pulse rise with an extremely high resolution of 10 ?m and tens of picoseconds. The results confirm the positive-streamer mechanism for Trichel pulse formation and provide supportive evidence for the hypothesis that the formation of a primary cathode-directed streamer occurs always in any streamer-initiated breakdown and prebreakdown phenomena associated with cathode spot formation. PMID:23214836

Hoder, Tomáš; Cernák, Mirko; Paillol, Jean; Loffhagen, Detlef; Brandenburg, Ronny

2012-11-01

226

The Effect of Nitrogen Sparging on the Long Term Stability of the Breakdown Electric Field Strength in a Repetitively Pulsed Oil Dielectric Switch  

Microsoft Academic Search

Summary form only given. Oil dielectrics, particularly hydrocarbon fluids, are often employed in applications involving dielectric breakdown. The reliability of the breakdown strength of the fluid, in its role as a switching medium, is frequently of great concern because unexpectedly low or high breakdown strength can produce timing errors, or worse yet, equipment failures. It is known from published investigations

P. Norgard; R. D. Curry; J. M. Turner

2007-01-01

227

Excitation in low-current discharges and breakdown in He at low pressures and very high electric field to gas density ratios E/N  

SciTech Connect

We investigate optical emission from low-current discharges in He at very high electric field to gas density ratios E/N between parallel plate electrodes. We also determine the electrical breakdown and the voltage-current behavior at low currents. The E/N are 300 Td to 9 kTd (1 Td=10{sup -21} V m{sup 2}) at pressures times electrode separations p{sub 0}d from 3 to 0.9 Torr cm. Absolute optical emission probabilities versus distance are determined for the 501.6 nm line (3 {sup 1}P{yields}2 {sup 1}S) and for the 587.6 nm line (3 {sup 3}D{yields}2 {sup 3}P) by reference to Boltzmann calculations at our lowest E/N and to published pressure dependent electron beam experiments. At E/N below 1 kTd, the emission follows the exponential growth of the electron density, while at above 7 kTd heavy particle excitation is evident near the cathode. Collisional transfer of excitation from the singlet to the triplet system dominates the 587.6 nm excitation. Comparisons of models with experiments show the importance of excitation and of electron production at the cathode by fast He atoms produced by charge transfer collisions of He{sup +} with He. The breakdown voltage versus p{sub 0}d is multivalued for p{sub 0}d{approx}1.5 Torr cm. At currents below 100 {mu}A and our lower E/N, the discharge voltage decreases linearly with current as expected for an increasing electron yield with ion energy and E/N at the cathode.

Jelenkovic, B.M.; Phelps, A.V. [JILA, University of Colorado and National Institute of Standards and Technology, Boulder, Colorado 80309-0440 (United States); Institute of Physics, P.O. Box 75, Belgrade (Serbia and Montenegro); JILA, University of Colorado and National Institute of Standards and Technology, Boulder, Colorado 80309-0440 (United States)

2005-01-01

228

Electrical characteristics of mammalian cells on porous supports  

NASA Astrophysics Data System (ADS)

The quantification of epithelial barrier functions by measuring the trans-epithelial electrical resistance (TER) and using the Electric Cell-substrate Impedance Sensing (ECIS) has been complicated by the current flowing inside the narrow space underneath cells. This thesis work, by examining the electrical characteristics of epithelial cells on porous supports, is aimed to tackle this problem. A mathematical model has been constructed to quantify the impedance from the various sources within a cell/electrode system. This model presents three cell-related parameters, alpha, Rb and Cm: alpha stands for the impedance contribution from the above-mentioned current underneath cells, Rb is an equivalent representation of epithelial barrier functions and Cm denotes the capacitive impedance of cell membranes. Analysis of the three parameters as well as the electrode impedance (Z e) has revealed two experimental approaches to reduce or eliminate the complication of alpha to the deduction of Rb: lowering alpha down to zero or lowering both Ze and alpha. The experimental realization of the first approach has been studied by examining the electrical characteristics of the African green monkey kidney (BS-C-1) and Madin-Darby canine kidney (MDCK-II) cells on porous filters of mixed esters of cellulose or nitrocellulose. A unique setup featuring a plastic/filter/plastic triple-layer structure was constructed to measure the impedance of cells on filters. With the extremely low alpha, all the electrical characteristics can be explained by using an equivalent circuit and Rb can be directly obtained from the resistance difference in the low frequency range. The second approach has been experimentally investigated by examining the electrical characteristics of BS-C-1 cells on porous/rough electrodes, i.e. the gold ECIS electrodes electrochemically coated with conducting polypyrrole/heparin composites or platinum black. Ze and alpha, especially the former, were found to be significantly lowered, which greatly reduces the effect of alpha and yields many new impedance features. Rb can be also directly obtained in a different way from that for the solely lowered alpha on the non-conducting porous filters.

Chen, Guo

2003-10-01

229

Proposed RF Breakdown Studies at the AWA  

SciTech Connect

A study of breakdown mechanism has been initiated at the Argonne Wakefield Accelerator (AWA). Breakdown may include several factors such as local field enhancement, explosive electron emission, Ohmic heating, tensile stress produced by electric field, and others. The AWA is building a dedicated facility to test various models for breakdown mechanisms and to determine the roles of different factors in the breakdown. We plan to trigger breakdown events with a high-powered laser at various wavelengths (IR to UV) to determine the role of explosive electron emission in the breakdown process. Another experimental idea follows from the recent work on a Schottky-enabled photoemission in an RF photoinjector that allows us to determine in situ the field enhancement factor on a cathode surface. Monitoring the field enhancement factor before and after the breakdown can shed some light on a number of observations such as the crater formation process.

Antipov, S.; Spentzouris, L. [Argonne National Laboratory, Argonne IL 60439 (United States); Illinois Institute of Technology, Chicago IL 60616 (United States); Conde, M.; Gai, W.; Power, J. G.; Yusof, Z. [Argonne National Laboratory, Argonne IL 60439 (United States); Dolgashev, V. [Stanford Linear Accelerator Center, Menlo Park CA 94025 (United States)

2006-11-27

230

Proposed RF Breakdown Studies at the AWA  

SciTech Connect

A study of breakdown mechanism has been initiated at the Argonne Wakefield Accelerator (AWA). Breakdown may include several factors such as local field enhancement, explosive electron emission, Ohmic heating, tensile stress produced by electric field, and others. The AWA is building a dedicated facility to test various models for breakdown mechanisms and to determine the roles of different factors in the breakdown. We plan to trigger breakdown events with a high-powered laser at various wavelengths (IR to UV) to determine the role of explosive electron emission in the breakdown process. Another experimental idea follows from the recent work on a Schottky-enabled photoemission in an RF photoinjector [1] that allows us to determine in situ the field enhancement factor on a cathode surface. Monitoring the field enhancement factor before and after the breakdown can shed some light on a number of observations such as the crater formation process.

Antipov, S.; Conde, M.; Gai, W.; Power, J.G.; Spentzouris, L.; Yusof, Z.; /Argonne /IIT, Chicago; Dolgashev, V.; /SLAC

2007-03-21

231

Proposed RF breakdown studies at the AWA.  

SciTech Connect

A study of breakdown mechanism has been initiated at the Argonne Wakefield Accelerator (AWA). Breakdown may include several factors such as local field enhancement, explosive electron emission, Ohmic heating, tensile stress produced by electric field, and others. The AWA is building a dedicated facility to test various models for breakdown mechanisms and to determine the roles of different factors in the breakdown. We plan to trigger breakdown events with a high-powered laser at various wavelengths (IR to UV) to determine the role of explosive electron emission in the breakdown process. Another experimental idea follows from the recent work on a Schottky-enabled photoemission in an RF photoinjector that allows us to determine in situ the field enhancement factor on a cathode surface. Monitoring the field enhancement factor before and after the breakdown can shed some light on a number of observations such as the crater formation process.

Conde, M.; Gai, W.; Power, J. G.; Yusof, Z.; Antipov, S.; Spentzouris, L.; Dolgashev, V.; High Energy Physics; IIT; Stanford Linear Accelerator Center

2006-01-01

232

Prediction of Treeing Breakdown from Pulse Height of Partial Discharge on Voltage-Phase Angle  

Microsoft Academic Search

This paper describes the change in the partial discharge (PD) characteristics due to the growth of electrical trees in insulating materials under the application of an AC voltage. An electrical tree consists of branch-like dielectric breakdown paths. Investigation of a number of characteristic PD parameters shows that the phi-q distribution profile has a good correlation with tree growth. The phi-q

Tatsuki Okamoto; Toshikatsu Tanaka

1985-01-01

233

Study of breakdown effects in silicon multiguard structures  

Microsoft Academic Search

The purpose of this work is to study layout solutions aimed at increasing the breakdown voltage in silicon micro-strip detectors. Several structures with multiple floating guards in different configurations have been designed and produced on high-resistivity silicon wafers. The main electrical characteristics of these devices have been measured before and after irradiation. Both radiation-induced surface and bulk damage effects were

M. Da Rold; N. Bacchetta; D. Bisello; A. Paccagnella; G.-F. Dalla Betta; G. Verzellesi; O. Militaru; R. Wheadon; P. G. Fuochi; C. Bozzi; R. Dell'Orso; A. Messineo; G. Tonelli; P. G. Verdini

1999-01-01

234

Electrical characteristics of 60Co ?-ray irradiated MIS Schottky diodes  

NASA Astrophysics Data System (ADS)

In order to interpret the effect of 60Co ?-ray irradiation dose on the electrical characteristics of MIS Schottky diodes, they were stressed with a zero bias at 1 MHz in dark and room temperature during ?-ray irradiation and the total dose range was 0-450 kGy. The effect of ?-ray exposure on the electrical characteristics of MIS Schottky diodes has been investigated using C- V and G/ ?- V measurements at room temperature. Experimental results show that ?-ray irradiation induces a decrease in the barrier height ?B and series resistance Rs, decreasing with increasing dose rate. Also, the acceptor concentration NA increases with increasing radiation dose. The C- V characteristics prove that there is a reaction for extra recombination centers in case of MIS Schottky diodes exposed to ?-ray radiation. Furthermore, the density of interface states Nss by Hill-Coleman method increases with increasing radiation dose. Experimental results indicate that the interface-trap formation at high irradiation dose is reduced due to positive charge build-up in the Si/SiO 2 interface (due to the trapping of holes) that reduces the flow rate of subsequent holes and protons from the bulk of the insulator to the Si/SiO 2 interface.

Tataro?lu, A.; Alt?ndal, ?.

2006-11-01

235

Improving Breakdown Behavior by Substrate Bias in a Novel Double Epi-layer Lateral Double Diffused MOS Transistor  

Microsoft Academic Search

A new lateral double diffused MOS (LDMOS) transistor with a double epitaxial layer formed by an n-type substrate and a p-type epitaxial layer is reported (DEL LDMOS). The mechanism of the improved breakdown characteristic is that the high electric field around the drain is reduced by substrate reverse bias, which causes the redistribution of the bulk electric field in the

Li Qi; Wang Wei-Dong; Liu Yun; Wei Xue-Ming

2012-01-01

236

49 CFR 236.8 - Operating characteristics of electromagnetic, electronic, or electrical apparatus.  

Code of Federal Regulations, 2010 CFR

... 2009-10-01 false Operating characteristics of electromagnetic, electronic, or electrical apparatus. 236.8 Section...Systems General § 236.8 Operating characteristics of electromagnetic, electronic, or electrical apparatus. Signal...

2009-10-01

237

49 CFR 236.8 - Operating characteristics of electromagnetic, electronic, or electrical apparatus.  

Code of Federal Regulations, 2013 CFR

... 2013-10-01 false Operating characteristics of electromagnetic, electronic, or electrical apparatus. 236.8 Section...Systems General § 236.8 Operating characteristics of electromagnetic, electronic, or electrical apparatus. Signal...

2013-10-01

238

49 CFR 236.8 - Operating characteristics of electromagnetic, electronic, or electrical apparatus.  

Code of Federal Regulations, 2010 CFR

... 2010-10-01 false Operating characteristics of electromagnetic, electronic, or electrical apparatus. 236.8 Section...Systems General § 236.8 Operating characteristics of electromagnetic, electronic, or electrical apparatus. Signal...

2010-10-01

239

Plasma breakdown and combustion ignition  

NASA Astrophysics Data System (ADS)

Ignition in chemically reactive media and electrical breakdown are among the most widely used transient processes. The two phenomena operate together during electrical (and laser) spark ignition of combustible gases. Analogs between them show up in Semenov's early (1920's) work on chemical chain reactions and on thermal breakdown of dielectrics. Both breakdown and ignition are under active study today. The energy source for breakdown is an applied electric field, and that for ignition, an applied flux of heat or radicals. Electrons and intermediate reactants are the corresponding driver particles, with a velocity difference that implies a vast difference in the growth rates for the two processes. Combustion takes place in a fuel-oxidant mixture, and an ignited reaction can proceed until the fuel or oxidant is depleted, while a (non-afterglow, non-fusion) plasma is sustained by an external power supply. The energy balance, propagation behavior, and time evolution of some specific forms of plasma breakdown and chemical ignition are further compared in order to illustrate their physical nature.

McNeill, Donald H.; Tran, Phuoc

2001-10-01

240

Locating Initial Breakdown Pulses of Lightning Flashes  

NASA Astrophysics Data System (ADS)

Lightning flashes often begin with a series of bipolar pulses, 1-5 us in width, called initial breakdown pulses or characteristic pulses. In this presentation we show electric field change data of initial breakdown pulses collected with a network of 5 flat-plate antennas with a bandwidth of 0 - 5 MHz. These pulses were obtained at the NASA/Kennedy Space Center (KSC) during the summer of 2010. The (x, y, z, t) positions of these pulses have been determined using a time of arrival technique [Koshak and Solakiewicz, JGR, 1996] for several lightning flashes. In addition, we also collected magnetic field change data with a LINET system [e.g., Betz et al., GRL, 2004], which consisted of 7 crossed-loop sensors having a bandwidth of 5 - 200 kHz; the pulse locations detected by this system were also determined by time of arrival. The locations of the initial breakdown pulses from both systems will be compared to locations of VHF lightning sources made with the KSC LDAR2 system (with a center frequency of 63 MHz and a bandwidth of 6 MHz). Possible implications of the pulse locations derived from the three different sets of sensors on lightning initiation and propagation will be discussed.

Karunarathne, S.; Marshall, T.; Stolzenburg, M.; Betz, H.; Wieczorek, G.

2010-12-01

241

Electrical Characteristics of Mesoporous Pure-Silica-Zeolite Film  

NASA Astrophysics Data System (ADS)

The dependence of the electrical characteristics of hydrothermally crystallized pure-silica-zeolite films on the water concentration in the precursor was investigated. Zeolite was crystallized in a silica-zeolite composite film after spin-coating the precursor, which was composed of tetraethylorthosilicate, tetrabutylammonium hydroxide, ethylalcohol, and deionized (DI) water, followed by calcinations at 400 °C. The results of Fourier-transform infrared (FT-IR) spectroscopy indicated that the number of Si-OH and O-H bonds decreased with an increase in the water concentration in the precursor. The dielectric constant of the film decreased with an increase in water concentration, while the leakage current increased.

Seo, Toshiki; Yoshino, Takenobu; Cho, Yoshinori; Hata, Nobuhiro; Kikkawa, Takamaro

2007-09-01

242

Phase formation, sintering behavior, and electrical characteristics of NASICON compounds  

Microsoft Academic Search

The dependence of phase formation, sintering behavior, and electrical characteristics of Sodium Superionic Conductor (NASICON) compounds on sintering temperature, time, and cooling process was investigated. In the von Alpen-type composition Na3.2Zr1.3Si2.2P0.8O10.5, ZrO2 second phase is in thermal equilibrium with crystalline NASICON and liquid phase above 1320°C, and when cooled through 1260–1320°C, the crystalline NASICON was formed by reaction between the

Hee-Bog Kang; N.-H. Cho

1999-01-01

243

Electrical characteristics of amorphous iron-tungsten contacts on silicon  

NASA Technical Reports Server (NTRS)

The electrical characteristics of amorphous Fe-W contacts have been determined on both p-type and n-type silicon. The amorphous films were obtained by cosputtering from a composite target. Contact resistivities of 1 x 10 to the -7th and 2.8 x 10 to the -6th were measured on n(+) and p(+) silicon, respectively. These values remain constant after thermal treatment up to at least 500 C. A barrier height of 0.61 V was measured on n-type silicon.

Finetti, M.; Pan, E. T.-S.; Nicolet, M.-A.; Suni, I.

1983-01-01

244

Measurement of AC electrical characteristics of SSC superconducting dipole magnets  

NASA Astrophysics Data System (ADS)

Experiments were conducted to measure the AC electrical characteristics of SSC superconducting dipole magnets over the frequency range of 0.1 Hz to 10 kHz. A magnet equivalent circuit representing the magnet DC inductance, eddy current losses, coil-to-ground, and turn-to-turn capacitance was synthesized from the experimental data. This magnet equivalent circuit can be used to predict the current ripple distribution along the superconducting magnet string and can provide dynamic information for the design of the collider current regulation loop.

Smedley, K. M.; Shafer, R. E.

1992-07-01

245

Electrical characteristics of GaAs nanocrystalline thin film  

NASA Astrophysics Data System (ADS)

GaAs nanocrystalline thin films containing 7-15 nm size crystallites were synthesized by an electrodeposition technique. A thin surface Ga 2O 3 layer was detected due to atmospheric oxidation of the GaAs nanocrystals. The above films were electrically characterized by the capacitance-voltage studies of the Au/nano-GaAs Schottky junctions. The effect of the nanostructure was fairly realized in the capacitance-voltage characteristics by the observation of capacitance peaks arising due to the trapping of the charge carriers by the surface states. The capacitance-voltage characteristics were recorded both at low and high frequencies of the impressed ac signal in order to identify the effect of the surface states on the behavior of the capacitance of the device.

Nayak, J.; Sahu, S. N.

2006-02-01

246

The Effect of Temperature, Degree of Thoriation and Breakdown on Field Currents from Tungsten and Thoriated Tungsten  

Microsoft Academic Search

Electron field currents from thoriated tungsten, with different degrees of thoriation, were found to be independent of temperature. The characteristic field current curve was found to be independent of the degree of thoriation of a thoriated tungsten filament. An electrical breakdown, a sudden discontinuity in the characteristic field current curve at which the current increases from small values usually considerably

A. J. Ahearn

1936-01-01

247

Dielectric Breakdown Lightning Model  

NSDL National Science Digital Library

The Dielectric Breakdown Lightning Model implements a common method for modeling lightning using a grid with regions of varying electric potential to simulate the electrical charge buildup during a lightning storm. To simulate the source of the lightning in the cloud, we set the potential to zero and place a small region of negative charge near the top of the grid. Along the bottom of the grid, we set the boundary potential to one to simulate the positive charge on the ground. All other grid points are given an initial electric potential equal to 0.5. After solving Laplace's equation, we examine all the grid points that are adjacent to a negative charge. We choose one adjacent point as the new growth site for the lightning, representing a point where the air is ionized and lightning will develop. The Dielectric Breakdown Lightning Model was developed as a final project in a sophomore-level Computational Physics course (Phy 200) using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the jar file will run the program if Java is installed. You can modify this simulation if you have EJS installed by right-clicking within the map and selecting "Open Ejs Model" from the pop-up menu item.

Castle, Sam

2012-06-16

248

AC and Impulse Breakdown of Liquid Nitrogen at 77 K for Quasi-Uniform Field Gaps  

SciTech Connect

Liquid nitrogen (LN2) is commonly used both as a coolant and electrical insulation in high temperature superconductor (HTS) equipment for power applications. Hence it is necessary to know the electrical breakdown characteristics of LN2 under a variety of conditions which are likely to be encountered in practice. The ac breakdown and positive and negative polarity breakdown results for lightning impulse (1.2 microsecond rise time/50 microsecond fall time) are presented for LN2 using sphere to plane electrode geometry for sphere diameters of 50.8 and 101.6 mm over a gap range of 1 to 15 mm. Voltages up to 110 kVrms were studied for ac breakdown and up to 500-kV peak for impulse. In this work both the ac and impulse breakdown voltages scale approximately with distance over the limited gaps studied which is indicative of a quasi-uniform (near- uniform) electric field between sphere and plane. These measurements were conducted in a dewar which could be pressurized from 1 to 2 bar absolute which greatly reduces the spontaneous formation of bubbles that can occur in open LN2 bath experiments and thus potentially reduce the breakdown strength. Results from the pressurized system and near atmospheric pressure similar to an open bath are compared.

James, David Randy [ORNL; Sauers, Isidor [ORNL; Ellis, Alvin R [ORNL; Schwenterly, S W [ORNL; Tuncer, Enis [ORNL; Pleva, Ed [Waukesha Electric Systems, Waukesha, WI

2008-01-01

249

Comparison of electrical characteristic between AlN/GaN and AlGaN/GaN heterostructure Schottky diodes  

NASA Astrophysics Data System (ADS)

Ni/Au Schottky contacts on AlN/GaN and AlGaN/GaN heterostructures are fabricated. Based on the measured current—voltage and capacitance—voltage curves, the electrical characteristics of AlN/GaN Schottky diode, such as Schottky barrier height, turn-on voltage, reverse breakdown voltage, ideal factor, and the current-transport mechanism, are analyzed and then compared with those of an AlGaN/GaN diode by self-consistently solving Schrödinger's and Poisson's equations. It is found that the dislocation-governed tunneling is dominant for both AlN/GaN and AlGaN/GaN Schottky diodes. However, more dislocation defects and a thinner barrier layer for AlN/GaN heterostructure results in a larger tunneling probability, and causes a larger leakage current and lower reverse breakdown voltage, even though the Schottky barrier height of AlN/GaN Schottky diode is calculated to be higher that of an AlGaN/GaN diode.

Lü, Yuan-Jie; Feng, Zhi-Hong; Lin, Zhao-Jun; Gu, Guo-Dong; Dun, Shao-Bo; Yin, Jia-Yun; Han, Ting-Ting; Cai, Shu-Jun

2014-02-01

250

The Effect of Electrically Prestressing on DC Breakdown Strength in the Nanocomposite of Low-density Polyethylene \\/ nano-SiOx  

Microsoft Academic Search

Nano-SiOx and micro-SiO2 particles were homogeneously dispersed in low-density polyethylene with double-solution method. The dc breakdown strength of the composite containing various contents of nano-SiOx was experimentally investigated, as well as the composite containing micro-SiO2. The breakdown strength of the nanocomposite is greater than that of pure LDPE. For example, the breakdown strength of the nanocomposite is 16% greater than

Yi Yin; Xiaobing Dong; Zhe Li; Xuguang Li

2007-01-01

251

Study on breakdown of magnet wire used in AC traction motor  

Microsoft Academic Search

AC traction motors are fed by fast switching inverters in express locomotive. Inter-turn insulation of AC traction motors is electrically more stressed than that in the conventional. In order to investigate the service life of AC traction motors, mechanism and characteristics of dielectric breakdown of magnet wire used in AC traction motors are studied in the paper. Experiments have been

Laisheng Tong; Guangning Wu; Guoqin Zhang; Tongguang Lin

2005-01-01

252

Analysis of the electrical characteristics of 600 V-Class electron irradiated fast recovery Superjunction VDMOS  

NASA Astrophysics Data System (ADS)

The design of a 600 V-Class Superjunction VDMOS (SJ-VDMOS) with fast recovery diode by electron irradiation is presented in this paper. Experimental measurements and numerical simulations are conducted in order to analyze the effect of the charge imbalance of the pillars and the fluence of electron irradiation on: the characteristics of the diode, the breakdown voltage, and the avalanche capability of the device. The experiments show that the breakdown voltage of the devices is influenced by the electron irradiation and the charge imbalance (C.I.) between the n- and p-pillars. The research results indicate that the breakdown voltage of the devices with higher doped p-pillars (Qp > Qn) increased due to the compensation of boron in the p-pillar after the electron irradiation process. Additionally, the single pulse avalanche energy capability of the devices is also investigated by simulations and experiments, and the results show that the avalanche characteristics of the devices with Qp > Qn are superior to the case of Qp = Qn and Qp < Qn after irradiation. Finally, the reverse recover charge (Qrr) of the devices has reduced by 62% after electron irradiation experiments without decreasing its breakdown voltage.

Zhu, Jing; Zhang, Long; Sun, Weifeng; Qian, Qinsong; Ma, Wenli; Yang, Zhuo; Lu, Shengli

2013-02-01

253

Electrodynamic thermal breakdown of a capacitor insulator  

NASA Astrophysics Data System (ADS)

A mechanism of the electrical breakdown is proposed for modern metal-field capacitors with the well-known property of self-healing of the breakdown strength. Upon an increase in the working voltage, the self-healing time increases to tens of microseconds, and the heating of adjacent insulator layers becomes significant. The propagating thermally activated conduction wave facilitates the enhancement of the electric field up to breakdown values. Analysis of the dynamics of electric field increase is carried out for capacitors based on polyethylene terephthalate (PET) dielectric.

Emel'Yanov, O. A.

2011-11-01

254

Time dependent breakdown in silicon dioxide films  

NASA Technical Reports Server (NTRS)

An investigation was conducted regarding the possible existence of a time-dependent breakdown mechanism in thermal oxides of the type used as gate oxide in MOS circuits. Questions of device fabrication are discussed along with details concerning breakdown measurements and the determination of C-V characteristics. A relatively large prebreakdown current observed in one of the cases is related to the time-dependent breakdown.

Svensson, C.; Shumka, A.

1975-01-01

255

Lightning Initiation by Runaway Air Breakdown  

Microsoft Academic Search

The maximum macroscopic electric fields measured in thunderstorms are generally found to exceed the threshold for runaway breakdown and lie below the threshold for initiating conventional breakdown. In order for the conventional process that has been studied extensively in the laboratory to initiate lightning discharges it is necessary therefore to invoke the existence of field enhancements (e.g. around water droplets)

R. A. Roussel-Dupré; E. M. Symbalisty; A. V. Gurevich; K. Zybin; L. Babich; I. Kutsyk

2003-01-01

256

Impulse breakdown delay in liquid dielectrics  

NASA Astrophysics Data System (ADS)

Theoretical images of streamers, revealing the mechanisms behind impulse breakdown in liquid dielectrics, are presented. Streamers lead to electrical breakdown by forming paths, capable of carrying large current amplitudes between electrodes. Breakdown delays and terminal currents are calculated for various electrode geometries (40 ?m needle and 6.35 mm sphere) and gap distances (up to 10 mm). Modeling results indicate that the breakdown in needle-needle electrodes requires higher impulse voltage amplitudes than in needle-sphere electrodes for the same gap distances. Streamers in needle-sphere geometries are about 50% thicker than streamers propagating in needle-needle geometries under similar impulse voltage amplitudes.

Jadidian, Jouya; Zahn, Markus; Lavesson, Nils; Widlund, Ola; Borg, Karl

2012-05-01

257

Breakdown voltage of zinc and magnesium vapours  

NASA Astrophysics Data System (ADS)

In this paper the findings of a study into the electrical breakdown of zinc and magnesium metal vapours are reported. The interest in the breakdown of these vapours lies in the fact that there is a growing interest in producing zinc–magnesium coated articles using physical vapour deposition. For commercial scale operations which require a high power input, a disturbance by electrical breakdown of the metal vapour is unacceptable. Hence, knowledge of the breakdown voltage and pressure relation of these elements is essential in the engineering of a set-up. To determine the breakdown of these metal vapours, a Knudsen effusion cell is built. It is proven that the flow through the Knudsen cell does not change the minimum breakdown voltage or location of this minimum, and is a reliable apparatus for determining the zinc and magnesium vapour data. The outcome of the experiments show that the minimum breakdown for zinc is in agreement with the reported data in the literature, around 350 V. Magnesium has a much lower minimum breakdown voltage than that found for zinc, around 110 V. Furthermore, the locations of the minimum breakdown voltages of both zinc and magnesium are found at around 4–7 Pa m and 1.5 Pa m respectively.

Zoestbergen, E.; Commandeur, C.; Maalman, T.

2014-06-01

258

Ageing and breakdown of thin insulating polymer films  

NASA Astrophysics Data System (ADS)

A mechanism of ageing and breakdown of thin insulating polymer films in an electric field is described. Ageing and breakdown are attributed to the field ionization of macromolecules which is regarded as a self-accelerating process that takes place during the entire electric lifetime and results in an abrupt current increase in the breakdown channel. Calculations are compared with experimental dependences of polymer film lifetimes on electric field intensity.

Zakrevskii, V. A.; Pakhotin, V. A.; Sudar, N. T.

2014-06-01

259

Nanolaminates: increasing dielectric breakdown strength of composites.  

PubMed

Processable, low-cost, high-performance hybrid dielectrics are enablers for a vast array of green technologies, including high-temperature electrical insulation and pulsed power capacitors for all-electric transportation vehicles. Maximizing the dielectric breakdown field (E(BD)), in conjunction with minimization of leakage current, directly impacts system performance because of the field's quadratic relationship with electrostatic energy storage density. On the basis of the extreme internal interfacial area and ultrafine morphology, polymer-inorganic nanocomposites (PNCs) have demonstrated modest increases in E(BD) at very low inorganic loadings, but because of insufficient control of the hierarchal morphology of the blend, have yielded a precipitous decline in E(BD) at intermediate and high inorganic volume fractions. Here in, we demonstrate that E(BD) can be increased up to these intermediate inorganic volume fractions by creating uniform one-dimensional nanocomposites (nanolaminates) rather than blends of spherical inorganic nanoparticles and polymers. Free standing nanolaminates of highly aligned and dispersed montmorillonite in polyvinyl butyral exhibited enhancements in E(BD) up to 30 vol % inorganic (70 wt % organically modified montmorillonite). These relative enhancements extend up to five times the inorganic fraction observed for random nanoparticle dispersions, and are anywhere from two to four times greater than observed at comparable volume fraction of nanoparticles. The breakdown characteristics of this model system suggested a trade-off between increased path tortuosity and polymer-deficient structural defects. This implies that an idealized PNC morphology to retard the breakdown cascade perpendicular to the electrodes will occur at intermediate volume fractions and resemble a discotic nematic phase where highly aligned, high-aspect ratio nanometer thick plates are uniformly surrounded by nanoscopic regions of polymer. PMID:22301841

Fillery, Scott P; Koerner, Hilmar; Drummy, Lawrence; Dunkerley, Erik; Durstock, Michael F; Schmidt, Daniel F; Vaia, Richard A

2012-03-01

260

Bulk charging and breakdown in electron-irradiated polymers  

NASA Technical Reports Server (NTRS)

High energy electron irradiations were performed in an experimental and theoretical study of ten common polymers. Breakdowns were monitored by measuring currents between the electrodes on each side of the planar samples. Sample currents as a function of time during irradiation are compared with theory. Breakdowns are correlated with space charge electric field strength and polarity. Major findings include evidence that all polymers tested broke down, breakdowns remove negligible bulk charge and no breakdowns are seen below 20 million V/m.

Frederickson, A. R.

1981-01-01

261

Characteristics and electrical addressing of optical Fabry-Perot displays  

NASA Astrophysics Data System (ADS)

In this paper further developments [1,2] of a passive matrix projection/direct view display are presented. The device uses micromachined and electrostatic actuated Fabry-Perot filters. Applications are surface topology measurements (stereographic projection) in small cavities, laser beam writing and pattern projection e.g. in Head-Mount-displays, automotive or information panels. The display pixels with diameters in the order of 100 ?m consist of a layer stack fabricated by LPCVD. The stack embeds an air gap which his created by a sacrificial etch process and a thin membrane which can be deflected electrostatically. The fabrication process has already been described elsewhere [2]. By membrane actuation the gap thickness is lowered and the interference spectrum generated by the layer stack is varied. The careful adjustment of the layer parameters like thickness and refractive index determines the design wavelength of the switches. They are assembled in rows and columns, resulting in an n*m-display matrix, where n*m actually is 4800. In principle the display may either be fabricated for transmission or reflection mode, depending on the substrate material (quartz or silicon). This paper focuses on transmissive displays. For pattern generation, an electric potential scan is applied on the n line contacts, and a video potential, which carries the image information, is addressed on the m column contacts. After each scan cycle, the potential polarities are reversed in order to avoid charge effects and to lower cross-talk between adjacent pixels. The response time is 100 ?s, which is at least an order of magnitude faster than for common LCD technology. Further advantages are high temperature stability, low power consumption and low production costs, since only five mask layers are used in the present process. In this paper especially the electrical characteristics are evaluated and an addressing scheme for future active matrix addressing is derived.

Knieling, T.; Lang, W.; Benecke, W.

2005-08-01

262

Secondary breakdown and degradation in germanium alloyed PN junctions  

Microsoft Academic Search

A failure mechanism is described that accounts for the degradation of the reverse characteristics of germanium alloyed junctions when pulsed in the reverse direction. This mechanism involves both surface breakdown and secondary breakdown. Visible avalanche breakdown emission has been observed at localized spots onreverse biased N+P junctions. Failure during pulsing always occurs at one of these spots. This observation together

G. H. Schneer; L. H. Holschwandner

1965-01-01

263

Electrical characteristics comparison between partially-depleted SOI and nMOS devices investigation using Silvaco  

Microsoft Academic Search

Investigation of electrical characteristics of partially-depleted SOI (silicon-on-insulator) and bulk-Si n-MOSFET devices in order to compare their electrical characteristics using Silvaco software was done and presented in this paper. Two specific channel lengths of the device that had been concentrated are 0.5 and 0.35 micron. The comparisons were focused on three main electrical characteristics that are leakage current, threshold voltage

YUSNIRA HUSAINI; MOHD HISYAM ISMAIL; AHMAD SABIRIN ZOOLFAKAR; NORHAZLIN KHAIRUDIN

2010-01-01

264

Electrical characteristics of amorphous molybdenum-nickel contacts to silicon  

NASA Technical Reports Server (NTRS)

The electrical characteristics of sputtered, amorphous Mo-Ni contacts have been measured on both p- and n-type Si, as functions of composition (30, 54, and 58 at. percent Mo). The contact resistivity on both p(+) and n(+) Si is in the 0.00000 ohm sq cm range. The barrier height for as-deposited samples varies between phi-bp = 0.47-0.42 V on p-type Si and between phi-bn = 0.63-0.68 V on n-type Si, as the composition of the amorphous layer goes from Ni-rich to Mo-rich. The sum phi-bp + phi-bn always equals 1.12 V, within experimental error. After thermal treatment at 500 C for 1/2 h, the contact resistivity changes by a factor of two or less, while the barrier height changes by at most approximately 0.05 V. In light of these results, the amorphous Mo-Ni film makes good ohmic contacts to silicon.

Kung, K. T.-Y.; Nicolet, M.-A.; Suni, I.

1984-01-01

265

Open-base Breakdown in Diffused NPN Junction Transistors†  

Microsoft Academic Search

A one-dimensional analysis is presented on the open-base breakdown characteristics of diffused n-p-n transistors. From breakdown voltage measurements upon selected devices—in conjunction with breakdown voltage calculations—‘ effective ’ values are established for the ionization rate of electrons in germanium and silicon p-n junctions, when biased substantially below avalanche breakdown. These ‘ effective ’ electron ionization rates are used to calculate

D. P. KENNEDY; R. R. OBRIEN

1965-01-01

266

Analysis of Electrical Characteristics of Thin Film Photovoltaic Cells  

NASA Technical Reports Server (NTRS)

Solar energy is the most abundant form of energy in many terrestrial and extraterrestrial environments. Often in extraterrestrial environments sunlight is the only readily available form of energy. Thus the ability to efficiently harness solar energy is one of the ultimate goals in the design of space power systems. The essential component that converts solar energy into electrical energy in a solar energy based power system is the photovoltaic cell. Traditionally, photovoltaic cells are based on a single crystal silicon absorber. While silicon is a well understood technology and yields high efficiency, there are inherent disadvantages to using single crystal materials. The requirements of weight, large planar surfaces, and high manufacturing costs make large silicon cells prohibitively expensive for use in certain applications. Because of silicon s disadvantages, there is considerable ongoing research into alternative photovoltaic technologies. In particular, thin film photovoltaic technologies exhibit a promising future in space power systems. While they are less mature than silicon, the better radiation hardness, reduced weight, ease of manufacturing, low material cost, and the ability to use virtually any exposed surface as a substrate makes thin film technologies very attractive for space applications. The research group lead by Dr. Hepp has spent several years researching copper indium disulfide as an absorber material for use in thin film photovoltaic cells. While the group has succeeded in developing a single source precursor for CuInS2 as well as a unique method of aerosol assisted chemical vapor deposition, the resulting cells have not achieved adequate efficiencies. While efficiencies of 11 % have been demonstrated with CuInS2 based cells, the cells produced by this group have shown efficiencies of approximately 1 %. Thus, current research efforts are turning towards the analysis of the individual layers of these cells, as well as the junctions between them, to determine the cause of the poor yields. As a student of electrical engineering with some material science background, my role in this research is to develop techniques for analyzing the electrical characteristics of the CuInS2 cells. My first task was to design a shadow mask to be used to place molybdenum contacts under a layer of CuInS;! in order to analyze the contact resistance between the materials. In addition, I have also analyzed evaporated aluminum top contacts and have tested various methods of increasing their thicknesses in order to decrease series resistance. More recently I have worked with other members of the research group in reviving a vertical cold-wall reactor for experimentation with CuInS2 quantum dots. As part of that project, I have improved the design for a variable frequency and pulse width square wave generator to be used in driving the precursor injection process. My task throughout the remainder of my tenure is to continue to analyze and develop tools for the analysis of electrical properties of the CuInS2 cells with the ultimate goal of discovering ways to improve the efficiency of our photovoltaic cells. Traditionally, photovoltaic cells are based on a single crystal silicon absorber. While The research group lead by Dr. Hepp has spent several years researching copper indium

Kasick, Michael P.

2004-01-01

267

Breakdown study of dc silicon micro-discharge devices  

NASA Astrophysics Data System (ADS)

The influence of geometrical and operating parameters on the electrical characteristics of dc microcavity discharges provides insight into their controlling physics. We present here results of such a study on silicon-based microcavity discharge devices carried out in helium at pressure ranging from 100 to 1000 Torr. Different micro-reactor configurations were measured. The differences include isolated single cavities versus arrays of closely spaced cavities, various cavity geometries (un-etched as well as isotropically and anisotropically etched), various dimensions (100 or 150 µm cavity diameter and 0-150 µm depth). The electrode gap was kept constant in all cases at approximately 6 µm. The applied electric field reaches 5 × 107 V m-1 which results in current and power densities up to 2 A cm-2 and 200 kW cm-3, respectively. The number of microcavities and the microcavity depth are shown to be the most important geometrical parameters for predicting breakdown and operation of microcavity devices. The probability of initiatory electron generation which is volume dependent and the electric field strength which is depth dependent are, respectively, considered to be responsible. The cavity shape (isotropic/anisotropic) and diameter had no significant influence. The number of micro-discharges that could be ignited depends on the rate of voltage rise and pressure. Larger numbers ignite at lower frequency and pressure. In addition, the voltage polarity has the largest influence on the electrical characteristics of the micro-discharge of all parameters, which is due to both the asymmetric role of electrodes as electron emitter and the non-uniformity of the electric field resulting in different ionization efficiencies. The qualitative shape of all breakdown voltage versus pressure curves can be explained in terms of the distance over which the discharge breakdown effectively occurs as long as one understand that this distance can depend on pressure.

Schwaederlé, L.; Kulsreshath, M. K.; Overzet, L. J.; Lefaucheux, P.; Tillocher, T.; Dussart, R.

2012-02-01

268

Physical and electrical characteristics of the high-k Ta2O5 (tantalum pentoxide) dielectric deposited on the polycrystalline silicon  

NASA Astrophysics Data System (ADS)

The high-k Ta2O5 films deposited on the polycrystalline silicon treated with different postrapid thermal annealing temperatures were formed as high-k interdielectrics. Physical and electrical characteristics of the Ta2O5 dielectrics were investigated with x-ray diffraction, x-ray photoelectron spectroscopy, atomic force microscopy, and electrical analysis. The annealing at 800 °C was found to be the optimal condition to reduce the defects and interface traps existed in the interface between the Ta2O5 dielectric and polysilicon to fabricate a well-crystallized film with higher breakdown field, lower leakage current and smaller charge trapping rate. This Ta2O5 dielectric shows promise for future generation of nonvolatile memory.

Kao, Chyuan-Haur; Chen, Hsiang; Chiu, Jing Sing; Chen, Kung Shao; Pan, Yu Tsung

2010-03-01

269

Rivaroxaban modulates electrical and mechanical characteristics of left atrium  

PubMed Central

Background Rivaroxaban reduces stroke in patients with atrial fibrillation (AF). Left atrium (LA) plays a critical role in the pathophysiology of AF. However, the electromechanical effects of rivaroxaban on LA are not clear. Results Conventional microelectrodes and a whole-cell patch-clamp were used to record the action potentials (APs) and ionic currents in rabbit LA preparations and isolated single LA cardiomyocytes before and after the administration of rivaroxaban. Rivaroxaban (10, 30, 100, and 300 nM) concentration-dependently reduced LA (n?=?7) AP durations at 90% repolarization (APD90) from 76?±?2 to 79?±?3, 67?±?4 (P?electrical and mechanical characteristics with direct ionic current effects.

2013-01-01

270

Realization of high breakdown voltage (>700 V) in thin SOI devices  

Microsoft Academic Search

The avalanche breakdown voltage of silicon on insulator (SOI) lateral diodes is investigated theoretically and experimentally. Theoretically, a condition is derived for achieving a uniform lateral electric field and thus optimizing the breakdown voltage. Using this condition, it is shown that, for SOI thicknesses below about 1 ?m, diode breakdown voltage increases with decreasing SOI layer thickness. Experimentally, breakdown voltages

S. Merchant; E. Arnold; H. Baumgart; S. Mukherjee; H. Pein; R. Pinker

1991-01-01

271

Characteristics of the slags produced in the fusion of scrap steel by electric arc furnace  

Microsoft Academic Search

The use of industrial by-products requires knowledge of the characteristics of the materials. This work presents characterization data on slags produced in the fusion of scrap steel by electric arc furnace. It includes the chemical, mineralogical, and microstructural analysis and physical characteristics. Mineralogically, scrap steel from electric arc furnace are a mix of anhydrous calcium silicates and iron composites and

M. P. Luxán; R. Sotolongo; F. Dorrego; E. Herrero

2000-01-01

272

Annealing Condition Dependence of Electrical Characteristics for Dy2O3\\/Si(100) Structures  

Microsoft Academic Search

In this paper, we report on the annealing condition dependence of electrical characteristics for Dy2O3 thin films deposited by MBE. Low temperature long time anneal decreased leakage current density with little interfacial layer growth. Excellent improvements of electrical characteristics and interfacial properties were confirmed.

Junichi Taguchi; Hiroyuki Yamamoto; Junichi Tonotani; Shun-ichiro Ohmi; Hiroshi Iwai

273

Modeling of transient electrical characteristics for granular semiconductors  

Microsoft Academic Search

Modeling of the electrical large-signal response of granular n-type semiconductors is carried out at following three different levels: (i) simple fully analytical model, (ii) semianalytical numerical model, and (iii) numerical device simulation. The electrical transients induced by both voltage and temperature changes are calculated. The analysis is based on the dynamic electrical model of the grain-boundary (GB) region, the drift-diffusion

Aapo Varpula

2010-01-01

274

Estimation of characteristic damage time of food materials in pulsed-electric fields  

Microsoft Academic Search

A method based on the electrical conductivity measurements is proposed to estimate the characteristic damage time (?) of a food material in pulsed-electric fields (PEF). Empirical dependencies of ? versus electric field intensity E are obtained for apple, carrot and potato tissues. The generalized electroporation theory accounting for the sphericity of biological cells and distribution of their geometric sizes gives

N. I Lebovka; M. I Bazhal; E Vorobiev

2002-01-01

275

dc breakdown conditioning and breakdown rate of metals and metallic alloys under ultrahigh vacuum  

NASA Astrophysics Data System (ADS)

The rf accelerating structures of the Compact Linear Collider (CLIC) require a material capable of sustaining high electric field with a low breakdown rate and low induced damage. Because of the similarity of many aspects of dc and rf breakdown, a dc breakdown study is underway at CERN in order to test candidate materials and surface preparations, and have a better understanding of the breakdown mechanism under ultrahigh vacuum in a simple setup. Conditioning speeds and breakdown fields of several metals and alloys have been measured. The average breakdown field after conditioning ranges from 100MV/m for Al to 850MV/m for stainless steel, and is around 170MV/m for Cu which is the present base-line material for CLIC structures. The results indicate clearly that the breakdown field is limited by the cathode. The presence of a thin cuprous oxide film at the surface of copper electrodes significantly increases the breakdown field. On the other hand, the conditioning speed of Mo is improved by removing oxides at the surface with a vacuum heat treatment, typically at 875°C for 2 hours. Surface finishing treatments of Cu samples only affect the very first breakdowns. More generally, surface treatments have an effect on the conditioning process itself, but not on the average breakdown field reached after the conditioning phase. In analogy to rf, the breakdown probability has been measured in dc with Cu and Mo electrodes. The dc data show similar behavior as rf as a function of the applied electric field.

Descoeudres, A.; Ramsvik, T.; Calatroni, S.; Taborelli, M.; Wuensch, W.

2009-03-01

276

Preparation of Iron Ultrafine Particles by the Dielectric Breakdown of Fe(CO)5 Using a Transversely Excited Atmospheric CO2 Laser and Their Characteristics  

Microsoft Academic Search

Iron ultrafine particles containing the gamma-phase in a relatively high yield of approx. 50% were prepared by the dielectric breakdown of Fe(CO)5 upon irradiation with a tightly focused laser beam of a transversely excited atmospheric (TEA) CO2 laser. CO is also obtained as a volatile product. The iron particles are fine and isotropic in shape. The particle size is in

Tetsuro Majima; Tesshu Miyahara; Koichi Haneda; Tadahiro Ishii; Michio Takami

1994-01-01

277

Characteristics of Pi2 Electric Pulsations at the Ionosphere  

NASA Astrophysics Data System (ADS)

At the onset of magnetospheric substorms, impulsive hydromagnetic oscillations occur with period range from 40 to 150 seconds. They are called Pi2 magnetic pulsations and occur globally in the magnetosphere. Pi2 has been studied with arrays of magnetometers on the ground and with in-situ observation by satellites. However Pi2 electric pulsation in the low-latitude ionosphere is not yet clarified sufficiently. Therefore we have focused on measuring Pi2 electric pulsations by an FM-CW radar. In order to detect the ionospheric electric fields we have built an FM-CW (HF) radar at Sasaguri, Fukuoka, Japan (Magnetic Latitude: 23.2 degree, Magnetic Longitude: 199.6 degree). The radar provides us Doppler information of the ionosphere by high-time resolution of 10 sec. When the eastward electric field penetrates into the low- latitude ionosphere, it drifts upward owing to the frozen-in effects of the F-region. In contrast to the penetration of the eastward electric field, the ionosphere drifts downward when the westward electric field penetrates. Thus we can measure the east-west ionospheric electric fields. From our ionospheric radar observation, Pi2 electric pulsation of about 0.2 mV/m amplitude can be identified in nightside at Nov.6, 2003. We also compared the Pi2 with geomagnetic field data obtained from Circum-pan Pacific Magnetic Network (CPMN) stations. As a result, we found a phase lag between the Pi2 electric pulsation and mightside magnetic Pi2 pulsation at Kujyu (KUJ; M. Lat. 23.6 degree, M. Lon. 203.2 degree).

Ikeda, A.; Yumoto, K.; Shinohara, M.; Nozaki, K.; Yoshikawa, A.; Uozumi, T.; Tokunaga, T.; Hirayama, Y.

2007-12-01

278

The breakdown phase in a coaxial plasma gun  

Microsoft Academic Search

The electrical breakdown in a coaxial plasma gun was investigated by means of optical and electrical measurements. The optimum start and operation conditions of the gun turned out to be strongly dependent on material and length of the cylindrical insulator.

A. Donges; G. Herziger; H. Krompholz; F. Rühl; K. Schönbach

1980-01-01

279

Electrical and Mechanical Characteristics of Epoxy-Nanoclay Composite  

Microsoft Academic Search

In this study, we investigated the effects of nanoclay additives on the electrical and mechanical properties of diglycidyl ether of bisphenol A (DGEBA) epoxy resin. Epoxy-clay nanocomposites were synthesized using organically modified two montmorillonite clays (MMT) with different interlamellar spacing (31.5 Å and 18.5 Å). The electrical and mechanical properties of epoxy-clay nanocopomosites were measured with variation of the amount

Hyun-Ji Noh; Sung-Pill Nam; Sung-Gap Lee; Byeong-Lib Ahn; Woo-Sik Won; Hyoung-Gwan Woo; Sang-Man Park

2009-01-01

280

Electrical charge characteristics of long-lived radioactive dust.  

PubMed

Respirable long-lived radioactive dust (LLRD), i.e., dust containing long-lived radionuclides such as 238U, 232Th, 226Ra, 224Ra and 228Th, interacts with unipolar and bipolar atmospheres through diffusion charging, electrical charge neutralization, and electrical self-charging mechanisms. Because of these interactions, and depending on the type of dust as well as its method of production, LLRD is found in electrically charged and neutral states. Electrical charge is important because it influences the deposition of particles in the human respiratory system. Particle size, electrical charge, and radioactive particle size distributions were measured in an area of an underground U mine where U ore crushing and transportation operations were conducted. In addition, concurrent measurements of 222Rn progeny and 220Rn progeny were made. A variety of instrumentation was used, such as particle counters. The electrical charge associated with dust generated in the primary crushing operation was substantially higher (3e- at 1 microns and approximately 500e- at 3 microns) than for the conveyor belt (2e- at 1 microns and approximately 50e- at 8 microns). In both cases the charge distribution was significantly higher than that predicted by Boltzmann's distribution. PMID:2155889

Bigu, J

1990-03-01

281

Electrical charge characteristics of long-lived radioactive dust  

SciTech Connect

Respirable long-lived radioactive dust (LLRD), i.e., dust containing long-lived radionuclides such as {sup 238}U, {sup 232}Th, {sup 226}Ra, {sup 224}Ra and {sup 228}Th, interacts with unipolar and bipolar atmospheres through diffusion charging, electrical charge neutralization, and electrical self-charging mechanisms. Because of these interactions, and depending on the type of dust as well as its method of production, LLRD is found in electrically charged and neutral states. Electrical charge is important because it influences the deposition of particles in the human respiratory system. Particle size, electrical charge, and radioactive particle size distributions were measured in an area of an underground U mine where U ore crushing and transportation operations were conducted. In addition, concurrent measurements of {sup 222}Rn progeny and {sup 220}Rn progeny were made. A variety of instrumentation was used, such as particle counters. The electrical charge associated with dust generated in the primary crushing operation was substantially higher (3e- at 1 microns and approximately 500e- at 3 microns) than for the conveyor belt (2e- at 1 microns and approximately 50e- at 8 microns). In both cases the charge distribution was significantly higher than that predicted by Boltzmann's distribution.

Bigu, J. (Elliot Lake Laboratory, CANMET, Energy, Mines and Resources Canada, Ontario (Canada))

1990-03-01

282

Breakdown phenomena in high power klystrons  

SciTech Connect

In the course of developing new high peak power klystrons at SLAC, high electric fields in several regions of these devices have become an important source of vacuum breakdown phenomena. In addition, a renewed interest in breakdown phenomena for nanosecond pulse, multi-megavolt per centimeter fields has been sparked by recent R and D work in the area of gigawatt RF sources. The most important regions of electrical breakdown are in the output cavity gap area, the RF ceramic windows, and the gun ceramic insulator. The details of the observed breakdown in these regions, experiments performed to understand the phenomena and solutions found to alleviate the problems will be discussed. Recently experiments have been performed on a new prototype R and D klystron. Peak electric fields across the output cavity gaps of this klystron exceed 2 MV/cm. The effect of peak field duration (i.e. pulse width) on the onset of breakdown have been measured. The pulse widths varied from tens of nanoseconds to microseconds. Results from these experiments will be presented. The failure of ceramic RF windows due to multipactor and puncturing was an important problem to overcome in order that our high power klystrons would have a useful life expectancy. Consequently many studies and tests were made to understand and alleviate window breakdown phenomena. Some of the results in this area, especially the effects of surface coatings, window materials and processing techniques and their effects on breakdown will be discussed. Another important source of klystron failure in the recent past at SLAC has been the puncturing of the high voltage ceramic insulator in the gun region. A way of alleviating this problem has been found although the actual cause of the puncturing is not yet clear. The ''practical'' solution to this breakdown process will be described and a possible mechanism for the puncturing will be presented. 9 refs., 5 figs., 3 tabs.

Vlieks, A.E.; Allen, M.A.; Callin, R.S.; Fowkes, W.R.; Hoyt, E.W.; Lebacqz, J.V.; Lee, T.G.

1988-03-01

283

SiO2 dielectric breakdown mechanism studied by the post-breakdown resistance statistics  

NASA Astrophysics Data System (ADS)

The dielectric breakdown mechanism of ultra-thin SiO2 is discussed on the basis of the experimental results of the post-breakdown resistance (Rbd) distribution. We have noticed that the Rbd of SiO2 in MOS devices is strongly related to the SiO2 breakdown characteristics such as the polarity dependence, the oxide field dependence or the oxidation process dependence of Qbd. In this paper, we discuss the dielectric breakdown mechanism of SiO2 from the viewpoint of the statistical correlation between the Rbd distribution, the Qbd distribution and the discharging energy at the SiO2 breakdown, by changing the stress polarity, the stress field, the oxide thickness and the oxidation process. In the case of hard breakdown, it has been clarified that the Rbd distribution for substrate electron injection is clearly different from that for gate electron injection. We have also found that, irrespective of the stress current density, the gate oxide thickness, the stressing polarity and the oxidation process, Rbd can be uniquely correlated to the discharging energy at dielectric breakdown, in the case of hard breakdown. Furthermore, it has been clarified that the Rbd does not depend on the energy dissipation at soft breakdown.

Satake, Hideki; Toriumi, Akira

2000-05-01

284

An Investigation of the Electrical Short Circuit Characteristics of Tin Whiskers  

NASA Technical Reports Server (NTRS)

Existing risk simulations make the assumption that when a free tin whisker has bridged two adjacent exposed electrical conductors, the result is an electrical short circuit. This conservative assumption is made because shorting is a random event that has a currently unknown probability associated with it. Due to contact resistance electrical shorts may not occur at lower voltage levels. In this experiment, we study the effect of varying voltage on the breakdown of the contact resistance which leads to a short circuit. From this data we can estimate the probability of an electrical short, as a function of voltage, given that a free tin whisker has bridged two adjacent exposed electrical conductors. Also, three tin whiskers grown from the same Space Shuttle Orbiter card guide used in the aforementioned experiment were cross-sectioned and studied using a focused ion beam (FIB). The rare polycrystalline structure seen in the FIB cross section was confirmed using transmission electron microscopy (TEM). The FIB was also used to cross section two card guides to facilitate the measurement of the grain size to determine that the tin plating on the card guides had a bright finish.

Courey, Karim J.

2008-01-01

285

Electrical characteristics of spark generators for automotive ignition  

NASA Technical Reports Server (NTRS)

This paper reports the results of an extensive program of measurements on 11 ignition systems differing widely in type. The results serve primarily to give representative data on the electric and magnetic constants of such systems, and on the secondary voltage produced by them under various conditions of speed, timing, shunting resistance, etc. They also serve to confirm certain of the theoretical formulas which have been proposed to connect the performance of such systems with their electrical constants, and to indicate the extent to which certain simplified model circuits duplicate the performance of the actual apparatus.

Brode, R B; Randolph, D W; Silsbee, F B

1927-01-01

286

Electrical characteristics of pentacene-based Schottky diodes  

Microsoft Academic Search

The current–voltage (I–V), capacitance–frequency (C–f), and capacitance–voltage (C–V) characteristics of organic diodes with a pentacene\\/aluminum Sckottky contact have been investigated. From the measured diode capacitances, it is revealed that the frequency-dependent properties are related to the localized traps in the band gap of pentacene. The C–V characteristics for different test frequencies are presented. In the low frequency region, the capacitance

Y. S Lee; J. H Park; J. S Choi

2003-01-01

287

Modelling of battery temperature effect on electrical characteristics of Li-ion battery in hybrid electric vehicle  

Microsoft Academic Search

This paper presents an enhanced modelling method for the commonly used energy storage device i.e. lithium-ion (Li-ion) battery of a hybrid electrical vehicle (HEV). In this enhanced modelling method, the thermal effect, an important part of the battery electrical model, is considered to generate a holistic understanding, hence the characteristic of the Li-ion battery. Because of the high temperature sensitivity

Yen Kheng Tan; J. C. Mao; King Jet Tseng

2011-01-01

288

Impact of electrical stress on the electrical characteristics of 2 MeV electron irradiated metal-oxide-silicon capacitors with atomic layer deposited Al2O3, HfO2 and nanolaminated dielectrics  

NASA Astrophysics Data System (ADS)

In this work, the impact of electrical stress on the electrical characteristics of 2 MeV electron irradiated metal-oxide-silicon capacitors with atomic layer deposited (ALD) high permittivity (high-k) dielectric layers of Al2O3, HfO2 and a nanolaminate of them is evaluated. The aim is to investigate the susceptibility to electrical stress of the radiation effects created in irradiated MOS structures, paying especial attention to any possible interaction between the radiation-induced damage and the subsequent electrical stress degradation. For this study, MOS capacitors with a nominal dielectric physical thickness of 10 nm (equivalent oxide thickness (EOT) between 3 nm and 7 nm) on different p-type and n-type silicon substrates were investigated. An exponentially increasing stress current was forced to flow in accumulation through the different dielectric layers, registering the evolution of gate voltage versus stress time until dielectric breakdown occurred. Capacitance-voltage characteristics of the different irradiated and non-irradiated structures are analyzed as a function of electrical stress. Different charge trapping behaviors and significant polarity dependence in interface state generation are observed for the dielectric layers subjected to substrate and gate injections. No clear interaction between radiation and electrical stress damages is noticed under substrate injection (n-type samples). However, higher negative charge trapping near the metal/dielectric interface is registered for the irradiated Al2O3 and nanolaminate layers subjected to gate injection and, in the case of the most irradiated samples, the radiation-induced interface states damage is found to dominate against the damage generated in early stages of the electrical stress.

Rafí, J. M.; González, M. B.; Takakura, K.; Tsunoda, I.; Yoneoka, M.; Beldarrain, O.; Zabala, M.; Campabadal, F.

2013-11-01

289

Comparison of the Microstructural Characteristics and Electrical Properties of Thermally Sprayed Al2O3 Coatings from Aqueous Suspensions and Feedstock Powders  

NASA Astrophysics Data System (ADS)

In this work the microstructural characteristics and electrical insulating properties of thermally sprayed alumina coatings produced by suspension-HVOF (S-HVOF) and conventional HVOF spray processes are presented. The electrical resistance at different relative air humidity (RH) levels (from 6 to 97% RH) and values of dielectric strength were investigated by direct current electrical resistance measurements, electrochemical impedance spectroscopy, and dielectric breakdown tests. Relationships between electrical properties and coating characteristics are discussed. At low humidity levels (up to 40% RH) the electrical resistivities of S-HVOF and HVOF coatings were on the same order of magnitude (1011 ?·m). At a very high humidity level (97% RH) the electrical resistivity values for the S-HVOF coatings were in the range 107-1011 ?·m, up to five orders of magnitude higher than those recorded for the HVOF coating (orders of magnitude of 106 ?·m). The better electrical resistance stability of the suspension-sprayed Al2O3 coatings can be explained by their specific microstructure and retention of a higher content of ?-Al2O3. The dielectric strength E d of suspension-sprayed coatings was found to be 19.5-26.8 kV·mm-1 for coating thicknesses ranging from 60 to 200 ?m. These values were slightly lower than those obtained for conventional HVOF coatings (up to 32 kV·mm-1). However, it seemed that the dielectric strength of conventionally sprayed coatings was more sensitive to the coating thickness (when compared with the values of E d determined for S-HVOF coatings) and varied to a greater extent (up to 10 kV·mm-1) when the coating thickness varied in the range 100-200 ?m.

Toma, Filofteia-Laura; Berger, Lutz-Michael; Scheitz, Stefan; Langner, Stefan; Rödel, Conny; Potthoff, Annegret; Sauchuk, Viktar; Kusnezoff, Mihails

2012-06-01

290

Electrical Characteristics of an Arc-Furnace Circuit.  

National Technical Information Service (NTIS)

A previously developed method of mathematical analysis related to the three phase arc furnace circuit has been updated and simplified. It has been applied to a variety of electric arc furnaces to define the magnitudes of arc voltage, ohmic resistances, re...

J. Persson

1984-01-01

291

Machining Characteristics of Polycrystalline Silicon by Wire Electrical Discharge Machining  

Microsoft Academic Search

This study examines the use of wire electrical discharge machining (WEDM) in machining polycrystalline silicon with resistivity of 2–3 ?cm. The effects of different WEDM parameters on cutting speed, machining groove width, and surface roughness are explored. Experimental results indicate that open voltage is the critical parameter in breaking the insulation of polycrystalline silicon, and that pulse-on time has the

Po-Huai Yu; Hsiang-Kuo Lee; Yang-Xin Lin; Shi-Jie Qin; Biing-Hwa Yan; Fuang-Yuan Huang

2011-01-01

292

Electrical Characteristics of Epoxy\\/nanoclay Nanodielectric Systems  

Microsoft Academic Search

The field of nanocomposites is a rapidly growing area of interest as more and more materials appear with exciting properties and novel applications. Nanocomposites based on clay systems have been widely investigated, where they have been shown to exhibit improved mechanical, thermal, optical and physicochemical properties. It is therefore of no surprise that the electrical properties of such nanocomposites are

T. N. Matheson; A. S. Vaughan; S. J. Sutton; A. Minigher

2007-01-01

293

Electrical Characteristics of Simulated Tornadoes and Dust Devils  

NASA Technical Reports Server (NTRS)

It is well known that tornadoes and dust devils have the ability to accumulate significant, visible clouds of debris. Collisions between sand-like debris species produce different electric charges on different types of grains, which convect along different trajectories around the vortex. Thus, significant charge separations and electric currents are possible, which as the vortex fluctuates over time are thought to produce ULF radiation signatures that have been measured in the field. These electric and magnetic fields may contain valuable information about tornado structure and genesis, and may be critical in driving electrochemical processes within dust devils on Mars. In the present work, existing large eddy simulations of debris-laden tornadoes performed at West Virginia University are coupled with a new debris-charging and advection code developed at Goddard Space Flight Center to investigate the detailed (meter-resolution) fluid-dynamic origins of electromagnetic fields within terrestrial vortices. First results are presented, including simulations of the electric and magnetic fields that would be observed by a near-surface, instrument-laden probe during a direct encounter with a tornado.

Zimmerman, Michael I.; Farrell, William M.; Barth, E. L.; Lewellen, W. S.; Perlongo, N. J.; Jackson, T. L.

2012-01-01

294

Performance Specification. Characteristics of 600 Volt DC Electrical Systems for Military Ground Vehicles.  

National Technical Information Service (NTIS)

The purpose of this specification is to provide a system of requirements for the electrical characteristics and safety of high voltage power distribution subsystems. This includes requirements for power sources, power distribution equipment, and power uti...

2010-01-01

295

The Effect of Electrical Conductivity Variations on the Characteristics of Arc Discharges.  

National Technical Information Service (NTIS)

Algebraically calculated current-voltage characteristics of arc discharges are obtained with a canal model for planar and cylindrical arcs and electrical conductivity given as a power of the heat flux potential. For slower than linear variation, the curre...

A. M. Whitman I. M. Cohen

1973-01-01

296

Specification for Brayton Isotope Power System (BIPS) electrical output power characteristics  

Microsoft Academic Search

The specification defines the Brayton Isotope Power System (BIPS) standards and characteristics for electrical power generation required to be maintained at utilizing equipments power-input terminals during generation and distribution.

Post

1976-01-01

297

Electrical Characteristics of Gd2O3 Thin Film Deposited on Si Substrate  

Microsoft Academic Search

Gadolinium oxide (Gd2O3) for high-k gate dielectric films were deposited on n-Si(100) substrates by e-beam evaporation to investigate their electrical characteristics. The electrical characteristics of Gd2O3 films were evaluated by fabricating Metal-Oxide-Semiconductor (MOS) capacitors. Gd2O3 thin films were confirmed amorphous after post deposition anneal in oxygen ambient at 400oC for 5min by XRD measurement. Formation of chemical oxide on Si

Chizuru Ohshima; I. Kashiwag; Shun-ichiro Ohmi; Hiroshi Iwai

2002-01-01

298

Electrical and Mechanical Characteristics of Epoxy-Nanoclay Composite  

NASA Astrophysics Data System (ADS)

In this study, we investigated the effects of nanoclay additives on the electrical and mechanical properties of diglycidyl ether of bisphenol A (DGEBA) epoxy resin. Epoxy-clay nanocomposites were synthesized using organically modified two montmorillonite clays (MMT) with different interlamellar spacing (31.5 Å and 18.5 Å). The electrical and mechanical properties of epoxy-clay nanocopomosites were measured with variation of the amount and type of clay. The nanocomposites were found to be homogenous materials although the nanocomposites still have clay aggregates with increasing nanoclay contents. The dielectric constant showed between 3.2 ~ 3.5 and the dielectric loss showed between 3.2 ~ 5.7% in all nanocoposites. The dielectric strength and tensile strength of the 5 wt% Cloisite 15A added epoxy-oclay nanocomposite were 23.9 kV/mm and 86.7 MPa, respectively.

Noh, Hyun-Ji; Nam, Sung-Pill; Lee, Sung-Gap; Ahn, Byeong-Lib; Won, Woo-Sik; Woo, Hyoung-Gwan; Park, Sang-Man

299

Treeing Breakdown in Inorganic-filler\\/LDPE Nanocomposite Material  

Microsoft Academic Search

A nano-composite material of magnesium oxide (MgO) added to a low-density polyethylene (LDPE) was subjected to electrical tree breakdown investigation. The LDPE without nano-fillers was lower in breakdown voltage than the LDPE added with nano-fillers. The breakdown voltage was increased by increase of nano-filler concentrations in LDPE. This result much coincided with the result on tree inception voltage which was

Rudi Kurnianto; Yoshinobu Murakami; Masayuki Nagao; Naohiro Hozumi; Yoshinao Murata

2007-01-01

300

Modeling of transient electrical characteristics for granular semiconductors  

NASA Astrophysics Data System (ADS)

Modeling of the electrical large-signal response of granular n-type semiconductors is carried out at following three different levels: (i) simple fully analytical model, (ii) semianalytical numerical model, and (iii) numerical device simulation. The electrical transients induced by both voltage and temperature changes are calculated. The analysis is based on the dynamic electrical model of the grain-boundary (GB) region, the drift-diffusion theory, and electronic trapping in the acceptor-type electronic interface states at the GBs. The electronic trapping is described using the standard rate equation. The models are verified by performing numerical device simulations using SILVACO ATLAS. The agreement between the proposed semianalytical model and ATLAS results is excellent during the whole transient and up to rather high electric fields. Compared to ATLAS, the calculations performed with the present semianalytical model are four orders of magnitude faster on a standard PC computer. The approximative analytical formulas describing the response are valid when the voltage and temperature changes are small. The semianalytical model is also fitted to reported experimental data obtained from dc and transient measurements of ZnO powder samples. The semianalytical model fits to the data well. The current in the GB region has following three components: potential-barrier limited current, charging and discharging current, and capacitive current. The results show that the large-signal transient responses of granular semiconductors are complex, as they vary highly in both duration and magnitude. During a transient the current can change many orders of magnitude. This is mainly caused by the change in the GB trap occupancy.

Varpula, Aapo

2010-08-01

301

Avalanche breakdown in GaTa4Se(8-x)Te(x) narrow-gap Mott insulators.  

PubMed

Mott transitions induced by strong electric fields are receiving growing interest. Recent theoretical proposals have focused on the Zener dielectric breakdown in Mott insulators. However, experimental studies are still too scarce to conclude about the mechanism. Here we report a study of the dielectric breakdown in the narrow-gap Mott insulators GaTa4Se(8-x)Te(x). We find that the I-V characteristics and the magnitude of the threshold electric field (Eth) do not correspond to a Zener breakdown, but rather to an avalanche breakdown. Eth increases as a power law of the Mott-Hubbard gap (Eg), in surprising agreement with the universal law Eth is proportional to Eg(2.5) reported for avalanche breakdown in semiconductors. However, the delay time for the avalanche that we observe in Mott insulators is over three orders of magnitude greater than in conventional semiconductors. Our results suggest that the electric field induces local insulator-to-metal Mott transitions that create conductive domains that grow to form filamentary paths across the sample. PMID:23591889

Guiot, V; Cario, L; Janod, E; Corraze, B; Phuoc, V Ta; Rozenberg, M; Stoliar, P; Cren, T; Roditchev, D

2013-01-01

302

Effect of the levels of intrinsic defects in the CdP{sub 2} band gap on electrical characteristics of corresponding structures with the Schottky barrier  

SciTech Connect

The electrical characteristics of Schottky barriers formed on n-type cadmium diphosphide are studied. It is established that the space-charge region at the metal-semiconductor interface represents in fact a Schottky layer formed owing to a high concentration of deep-level centers. The charge transport in the conducting direction for these structures is related to the above-barrier emission of electrons and is consistent with the diffusion theory for one or two types of charge carriers. The high concentration of ionized centers in the space-charge region gives rise to the tunneling mechanism of breakdown in the blocking direction. The frequency dependences of the complex conductance are governed by the exchange of charge carriers between the conduction band and donors that specify the conductivity type of the material and also by the recharing of the centers with a large depth of levels. Good agreement between the reported results and the theory is obtained.

Stamov, I. G., E-mail: istamov51@mail.ru; Tkachenko, D. V. [Dniester State University (Moldova, Republic of)

2006-10-15

303

Evaluating thermal aging characteristics of electric power transmission lines  

Microsoft Academic Search

Assessment of aging characteristics of conductors and other components of power transmission networks plays an important role in asset management systems. Due to adverse effects of conductor aging caused by annealing, the conductors lose their tensile strength. Although the loss of strength is gradual, it accumulates over time and increases the probability of outages and blackouts. Therefore, the most important

M. M. I. Bhuiyan; P. Musilek; J. Heckenbergerova; D. Koval

2010-01-01

304

Electrically Loaded Yagi-Uda Antenna Optimizations Using Characteristic Modes And Differential Evolution  

Microsoft Academic Search

A novel procedure based on characteristic modes (CM) and differential evolution (DE) algorithm is proposed for electrically loaded Yagi-Uda antenna synthesis. In this method, optimal Yagi- Uda antenna designs are realized by electrically loading, other than by tuning the sensitive physical dimensions. The traditional fullwave analysis in objective function evaluations is replaced by a simple summation of the CM, thus

Y. Chen; C.-F. Wang

2012-01-01

305

Effect of liquid nitrogen flowing on electrical characteristics of cryogenic insulation systems  

Microsoft Academic Search

Effect of liquid nitrogen flowing on electrical characteristics of cryogenic insulation systems was studied. It was observed that the flowing of liquid nitrogen improves electrical performance of the insulation systems though the degree of improvement is different among the systems. This phenomenon may be attributed to restraint of inception and\\/or propagation of discharges by liquid nitrogen flowing

Y. Mizuno; T. Kimura; K. Asada; K. Naito

1997-01-01

306

Propagation characteristics of picosecond electrical transients on coplanar striplines  

SciTech Connect

Using a cryogenic electro-optic sampling technique, we have studied the transient propagation characteristics of superconducting and normal indium lines in the picosecond regime. Transient dispersion effects, including increased rise time and increased pulse width, the introduction of ringing on the waveform, and a novel ''pulse sharpening'' were observed. A model that takes into consideration the effects of modal dispersion and superconducting complex conductivity was established, and an algorithm was developed that accurately describes all of the experimental findings.

Hsiang, T.Y.; Whitaker, J.F.; Sobolewski, R.; Dykaar, D.R.; Mourou, G.A.

1987-11-09

307

Research on Electrical Characteristics of Dielectric Barrier Discharge and Dielectric Barrier Corona Discharge  

NASA Astrophysics Data System (ADS)

The dielectric barrier corona discharge (DBCD) in a wire-cylinder configuration and the dielectric barrier discharge (DBD) in a coaxial cylinder configuration are studied. The discharge current in DBD has higher pulse amplitude than in DBCD. The dissipated power and the gas gap voltage are calculated by analyzing the measured Lissajous figure. DBCD has lower gas gap breakdown voltage. The average electric field is about 10--20 kV/cm in gas gap during DBCD, and is 30--40 kV/cm during DBD. In the positive half cycle the DBCD appears as continuous discharge current mode and in negative half cycle it appears as Trichel pulse mode. Under some conditions DBCD can show homogeneous diffuse discharges mode.

Sun, Yanzhou; Zeng, Mi; Cui, Zhiyong

2012-09-01

308

Role of the substrate in the electrical transport characteristics of focused ion beam fabricated nanogap electrode  

SciTech Connect

Precise metallic nanogap structure is fabricated on a glass substrate by using a 30 keV focused Ga ion beam. While investigating the I-V behavior of the nanogap structure, tunneling through the substrate has been found to play a vital role in the electrical transportation process. Substrate breakdown occurs at a certain applied voltage and a metal vapor state is initiated through intense heat generation at the nanogap region. The experimental observation confirms the role of the substrate in the explosion process. Metallic spherical particles are formed during cooling/condensation of the metal vapors or splashing of the liquid droplets showing a wide distribution of size from few tens of nanometers to few microns.

Rajput, Nitul S.; Verma, H. C. [Department of Physics, Indian Institute of Technology Kanpur, Kanpur 208016 (India); Singh, Abhishek K. [Materials Science Programme, Indian Institute of Technology Kanpur, Kanpur 208016 (India)

2012-07-15

309

Dielectric breakdown in silica-amorphous polymer nanocomposite films: the role of the polymer matrix.  

PubMed

The ultimate energy storage performance of an electrostatic capacitor is determined by the dielectric characteristics of the material separating its conductive electrodes. Polymers are commonly employed due to their processability and high breakdown strength; however, demands for higher energy storage have encouraged investigations of ceramic-polymer composites. Maintaining dielectric strength, and thus minimizing flaw size and heterogeneities, has focused development toward nanocomposite (NC) films; but results lack consistency, potentially due to variations in polymer purity, nanoparticle surface treatments, nanoparticle size, and film morphology. To experimentally establish the dominant factors in broad structure-performance relationships, we compare the dielectric properties for four high-purity amorphous polymer films (polymethyl methacrylate, polystyrene, polyimide, and poly-4-vinylpyridine) incorporating uniformly dispersed silica colloids (up to 45% v/v). Factors known to contribute to premature breakdown-field exclusion and agglomeration-have been mitigated in this experiment to focus on what impact the polymer and polymer-nanoparticle interactions have on breakdown. Our findings indicate that adding colloidal silica to higher breakdown strength amorphous polymers (polymethyl methacrylate and polyimide) causes a reduction in dielectric strength as compared to the neat polymer. Alternatively, low breakdown strength amorphous polymers (poly-4-vinylpyridine and especially polystyrene) with comparable silica dispersion show similar or even improved breakdown strength for 7.5-15% v/v silica. At ?15% v/v or greater silica content, all the polymer NC films exhibit breakdown at similar electric fields, implying that at these loadings failure becomes independent of polymer matrix and is dominated by silica. PMID:23639183

Grabowski, Christopher A; Fillery, Scott P; Westing, Nicholas M; Chi, Changzai; Meth, Jeffrey S; Durstock, Michael F; Vaia, Richard A

2013-06-26

310

Fusion characteristics of plant protoplasts in electric fields.  

PubMed

The electrical parameters important in the fusion of plant protoplasts aligned dielectrophoretically in high-frequency alternating electric fields have been established. Protoplasts were aligned in an alternating electric field between two relatively distant (1 mm) electrodes, by dielectrophoresis induced by field inhomogeneities caused by the protoplasts themselves. This arrangement allowed ease of manipulations, large throughput and low loss of protoplasts. In analytical experiments, sufficiently large samples could be used to study pulse duration-fusion response relations at different pulse voltages for protoplasts of different species, tissues and size (mesophyll protoplasts of Solanum brevidens, Triticum aestivum, Hordeum vulgare; suspension-culture protoplasts of Nicotiana sylvestris, N. rustica, Datura innoxia and S. brevidens; root-tip protoplasts of Vicia faba, hypocotyl protoplasts of Brassica napus). The percentage of aligned protoplasts that fused increased with increasing pulse parameters (pulse duration; voltage) above a threshold that was dependant on pulse voltage. The maximum fusion values obtained depended on a number of factors including protoplast origin, size and chain length. Leaf mesophyll protoplasts fused much more readily than suspension-culture protoplasts. For both types, there was a correlation of size with fusion yield: large protoplasts tended to fuse more readily than small protoplasts. In short chains (?five protoplasts), fusion frequency was lower, but the proportion of one-to-one products was greater than in long chains (?ten protoplasts). In formation by electrofusion of heterokaryons between mesophyll and suspension-culture protoplasts, the fusion-frequency response curves reflected those of homofusion of mesophyll protoplasts rather than suspension-culture protoplasts. There was no apparent limitation to the fusion of the smallest mesophyll protoplast with the largest suspension-culture protoplasts. Based on these observations, it is possible to direct fusion towards a higher frequency of one-to-one (mesophyll/suspension) products by incorporating low densities of mesophyll protoplasts in high densities of suspensionculture protoplasts and by using a short fusion pulse. The viability of fusion products, assessed by staining with fluorescein diacetate, was not impaired by standard fusion conditions. On a preparative scale, heterokaryons (S. brevidens mesophyll-N. sylvestris or D. innoxia suspension-culture) were produced by electrofusion and cultured in liquid or embedded in agar, and were capable of wall formation, division and growth. It is concluded that the electrode arrangement described is more suitable for carrying out directed fusions of plant protoplasts than that employing closer electrodes. PMID:24241045

Tempelaar, M J; Jones, M G

1985-08-01

311

Vortex breakdown simulation  

NASA Technical Reports Server (NTRS)

A vortex breakdown was simulated by the vortex filament method, and detailed figures are presented based on the results. Deformations of the vortex filaments showed clear and large swelling at a particular axial station which implied the presence of a recirculation bubble at that station. The tendency for two breakdowns to occur experimentally was confirmed by the simulation, and the jet flow inside the bubble was well simulated. The particle paths spiralled with expansion, and the streamlines took spiral forms at the breakdown with expansion.

Nakamura, Y.; Leonard, A.; Spalart, P. R.

1985-01-01

312

Microstructure and electrical characteristics of sputtered indium tin oxide films  

SciTech Connect

The relationship between microstructure and electron characteristics of indium tim oxide (ITO) films was investigated. The microstructure and resistivity were found to be dependent on the oxygen partial pressure in the sputtering ambient. Lower resistivity ITO films had a domain structure and a small amount of surface roughness. The small roughness and the large size domain structure caused a decrease in electron scattering, and hence an increase in mobility. Crystallinity was also affected by the oxygen partial pressure. For ITO films with a domain structure, the relative X-ray diffraction intensity of the (440) crystal plane increased.

Higuchi, Masatoshi; Sawada, Masato; Kuronuma, Yoichiro (Toshiba Corp., Yokohama (Japan). Manufacture Engineering Research Center)

1993-06-01

313

Electrical characteristics of barium strontium titanate-oxide composite films  

SciTech Connect

In a previous work, composites of BSTO combined with other nonelectrically active oxide ceramics have been formulated and have demonstrated adjustable electronic properties which can be tailored for use in various electronic devices. One application has been for use in phased array antennas and insertion has been accomplished into several working antenna systems. To further accommodate the frequencies required by these phased array antennas, thin films of the composites have been fabricated using a Krypton Fluoride excimer laser as an ablation source. The electrical properties, including the dielectric constant and the tunability (change in the dielectric constant with applied voltage) have been measured. The results have been compared to those obtained for the bulk ceramic composites and other BSTO/oxide composite thin film structures.

Sengupta, S.; Sengupta, L.C.; Stowell, S.; Vijay, D.P.; Desu, S.B.

1994-12-01

314

Breakdown Phenomena in Nitrogen Due to Repetitive Nanosecond-pulses  

Microsoft Academic Search

Nanosecond-pulse breakdown indicates special characteristics depending on the pulse rise-time and duration. Based on a repetitive nanosecond-pulse generator, breakdown phenomena of parallel-plane gaps in nitrogen were investigated with single pulse and repetitive bursts under different gap conditions. The relationships between applied voltage, pulse repetition frequency, breakdown time lag, repetitive pulse stress time and the number of applied pulses are presented.

Tao Shao; Guangsheng Sun; Ping Yan; Shichang Zhang

2007-01-01

315

Microwave Breakdown in RF Devices Containing Sharp Corners  

Microsoft Academic Search

The present work reports on an analytical, numerical, and experimental analysis of the importance of electric field singularities around sharp corners for the determination of the breakdown strength of microwave RF devices. It is shown that only under certain physical circumstances, does the singularity and the concomitant strongly enhanced microwave field determine the breakdown strength. In particular, in situations where

T. Olsson; U. Jordan; D. S. Dorozhkina; V. Semenov; D. Anderson; M. Lisak; J. Puech; I. Nefedov; I. Shereshevskii

2006-01-01

316

Dielectric Breakdown and its Influence on Ignition.  

National Technical Information Service (NTIS)

Electrical conduction, dielectric breakdown and the consequent ignition of small pellets, 0.2 to 5 mm in thickness and 5 to 7 mm in diameter, of MTV compositions SR886B, SR886E and SR886E have been investigated. The investigations were made using d.c fiel...

M. M. Chaudhri F. A. Al-Ramadhan I. U. Haq

1993-01-01

317

Non-Uniform Field Breakdown and Surface Flashover in Liquid Nitrogen Gaps for HTS Applications  

SciTech Connect

Abstract: Liquid nitrogen (LN2) is used as a coolant and electrical insulation in many High Temperature Superconducting (HTS) applications. Hence a good understanding of the breakdown characteristics of this medium under a variety of practical electrode geometries and conditions is needed for design of high voltage equipment. While there is considerable literature on breakdown of LN2 gaps for uniform (plane-plane) or quasi-uniform electric fields (sphere-plane), there is much less data available for highly non-uniform field gaps and for surface flashover along insulators. In this paper we present results on sphere-plane and cylindrical rod-plane gaps in LN2 as a function of sphere and rod diameters and radius of the rod edge at 1 bar pressure. In addition the surface flashover voltages of Fiber-Reinforced Plastic (FRP) in LN2 with these electrode arrangements will also be reported.

James, David Randy [ORNL; Sauers, Isidor [ORNL; Tuncer, Enis [ORNL; Ellis, Alvin R [ORNL; Tekletsadik, Kasegn [Consultant, SuperPower, Inc.; Hazelton, Drew [SuperPower Incorporated, Schenectady, New York

2006-01-01

318

Some observations on the electrical characteristics of radioactive (222Rn progeny) and nonradioactive aerosols.  

PubMed

The electrical characteristics of 222Rn, 222Rn progeny atmospheres have been investigated. Experiments were conducted in a 222Rn/220Rn Test Facility (RTTF) of the walk-in type using an electrical elutriator of the split-flow variety, originally designed by Johnston. Experiments were carried out with the "undisturbed" atmosphere, and when this atmosphere was exposed to a source of electrically charged particles produced by a negative ion-generator. Under normal conditions, the average electrical charge of the 222Rn, 222Rn progeny atmosphere was substantially less than one elementary unit. Under the influence of the ion-generator, however, the electrical charge exceeded two elementary units, and the electrical charge distribution was non-symmetrical. It was found that the particle concentration in the RTTF substantially decreased with the operation of the ion-generator. PMID:2152892

Bigu, J

1990-01-01

319

Electric characteristic of nickel oxide film for the mirobolometer  

NASA Astrophysics Data System (ADS)

In this report, we describe the two different nickel oxide film formation processes for microbolometer application: the heat treatment of nickel metal and the reactive sputtering. Nickel oxide films obtained by the heat treatment of nickel show high TCR(about -3.2/°C) and low 1/f noise characteristic. The reactively sputtered nickel oxide films have the wide range of resistivity according to the sputtering vacuum level, time, and O2/Ar gas partial pressure. The acquired TCR of sputtered films are in the range of -1.4%/°C and -3.45%°C. And the 1/f noise parameter k, which shows the performance between VOx and a-Si, is as low as 8.5×10-13 at the TCR of -1.75%/°C. Acquired nickel oxide films were analyzed from XRD, AFM methods, and etc. It is regarded that the resistivity variation of polycrystalline nickel oxide film comes from nonstoichiometric property of nickel and oxygen atoms. We simulated the optic and membrane structure for predicting the performance of a microbolometer with nickel oxide film. The estimated NETD(noise equivalent temperature difference) for the 50?mx50?m size of pixel is NETD below 20mK.

Lee, Yong Soo; Kim, Dong Soo; Jung, Young-Chul; Lee, Hee Chul

2011-05-01

320

Impulse partial discharge characteristics and their mechanisms under non-uniform electric field in N2\\/SF6 gas mixtures  

Microsoft Academic Search

We have investigated impulse partial discharge (PD) and breakdown (BD) characteristics of a needle-plane gap in N2\\/SF6 gas mixtures under positive lightning impulse voltage application, and discussed their physical mechanisms. The 50% probability PD inception voltage (PDIV50), leader discharge onset voltage (LOV) and BD voltage (BDV50) were measured and analyzed as a function of gas pressure and SF6 content. Experimental

Naoki Hayakawa; Yuichiro Yoshitake; Naoto Koshino; Toshiaki Ueda; Hitoshi Okubo

2005-01-01

321

Characteristics of the calibration curves of copper for the rapid sorting of steel scrap by means of laser-induced breakdown spectroscopy under ambient air atmospheres.  

PubMed

For the rapid and precise sorting of steel scrap with relatively high contents of copper, laser-induced breakdown spectroscopy (LIBS) is a promising method. It has several advantages such that it can work under ambient air atmospheres, and specimens can be tested without any pretreatment, such as acid digestion, polishing of the surface of the specimens, etc. For the application of LIBS for actual steel scrap, we obtained emission spectra by an LIBS system, which was mainly comprised of an Nd:YAG laser, an Echelle-type spectrometer, and an ICCD detector. The standard reference materials (SRMs) of JISF FXS 350-352, which are Fe-Cu binary alloy and have certified concentrations of copper, were employed for making calibration lines. Considering spectral interferences from the emission lines of the iron matrix in the alloys, Cu I lines having wavelengths of 324.754 and 327.396 nm could be chosen. In five replicate measurements of each SRM, shorter delay times after laser irradiation and longer gate widths for detecting the transient emission signal are suggested to be the optimal experiment parameters. In the determination process, utilizing the calibration line from Cu I 327.396 nm was better because of less spectral interference. By using 200 pulsed laser shots for the measurement sequence, a limit of detection of 0.004 Cu at% could be obtained. PMID:24334981

Kashiwakura, Shunsuke; Wagatsuma, Kazuaki

2013-01-01

322

Microwave air breakdown enhanced with metallic initiators  

Microsoft Academic Search

We have determined X-band (9.4 GHz) electric field strengths required to obtain air breakdown at atmospheric pressure in the presence of metallic initiators, which are irradiated with repetitive (30 pulses\\/s) microwave pulses of 3 mus duration and 200 kW peak power. Using a half-wavelength initiator, a factor of 40 reduction (compared to no initiator) was observed in the electric field

G. C. Herring; S. Popovic

2008-01-01

323

An approach for the mathematical description of aircraft electrical systems' load characteristics including electrical dependences validation  

Microsoft Academic Search

Aeroplane design is defined by many objectives. One of them is the reduction of weight while maintaining safety, functions and performance. As power measurement campaigns have revealed, weight can be saved, as the electrical system exhibits low capacity utilisation. This is, as there are many requirements (on certification, safety and function) to meet. Also, there are systems, which do not

Torben Schroeter; Detlef Schulz

2010-01-01

324

Breakdown During High-Field Bias-Temperature Stress.  

National Technical Information Service (NTIS)

Measurements of dielectric breakdown during high-field electrical stress are typically performed at or near room temperature via constant voltage or current stress methods. In this summary they explore whether useful information might also be obtained by ...

D. M. Fleetwood K. S. Krisch F. W. Sexton

1999-01-01

325

The electrical characteristics of pentacene-based organic field-effect transistors with polymer gate insulators  

Microsoft Academic Search

We have studied the electrical characteristics of pentacene field-effect transistors with the polymer insulators such as polymethyl methacrylate (PMMA) or poly-4-vinylphenol (PVP). The dependence of the field-effect mobility on the electric field and the temperature were measured to understand the conduction mechanism in the pentacene thin film. The transistor with PVP gate insulator shows higher field-effect mobility, ?FET=0.15 cm2\\/Vs, and

G.-W. Kang; K.-M. Park; J.-H. Song; C. H. Lee; D. H. Hwang

2005-01-01

326

Criterion for spark-breakdown in non-uniform fields  

NASA Astrophysics Data System (ADS)

We develop a criterion for spark-breakdown in non-uniform field geometries with positive polarity and small electrode separations so that breakdown evolves without the formation of a leader. We arrive at the spark-breakdown criterion by framing it in terms of gain and instability conditions, whose relative importance is established from an analysis of the experimental breakdown characteristics and correlations with streamer behavior in short gaps. Results are presented in the context of two generic geometries having coaxial and point-plane electrodes. For nearly uniform field situations, we re-confirm that the breakdown criterion obtained by the usual extension of either the Townsend or Meek criteria satisfactorily predicts the experimental results. On the other hand, for increasing non-uniformity, the results for the corona and spark branches of the breakdown characteristics are shown inconsistent with a breakdown criterion solely based on either the Townsend or streamer mechanisms. In particular, the avalanche gain factor, the primary component of the Townsend and streamer criteria, does not determine the spark breakdown criterion. Streamers can cross the gap for a significantly wide range of applied voltages without triggering a spark. We find that it is the instability condition, derived from a relation between the minimum Laplacian field in the gap and the local streamer body field (which we relate to the streamer sustaining field), that is sufficient for determining the spark threshold thereby yielding a breakdown criterion.

K. Warne, L.; Jorgenson, R. E.; Kunhardt, E. E.

2014-04-01

327

Effect of RF Parameters on Breakdown Limits in High-Vacuum X-Band Structures  

Microsoft Academic Search

RF breakdown is one of the major factors determining performance of high power rf components and rf sources. RF breakdown limits working power and produces irreversible surface damage. The breakdown limit depends on the rf circuit, structure geometry, and rf frequency. It is also a function of the input power, pulse width, and surface electric and magnetic fields. In this

Valery A. Dolgashev; Valery A

2003-01-01

328

Optical and RF electrical characteristics of atmospheric pressure open-air hollow slot microplasmas and application to bacterial inactivation  

NASA Astrophysics Data System (ADS)

We report electrical properties of radio frequency (RF)-driven hollow slot microplasmas operating in open air but with uniform luminous discharges at RF current densities of the order of A cm-2. We employ interelectrode separations of 100-600 µm to achieve this open-air operation but because the linear slot dimension of our electrode designs are of extended length, we can achieve, for example, open-air slot shaped plasmas 30 cm in length. This creates a linear plasma source for wide area plasma driven surface treatment applications. RF voltages at frequencies of 4-60 MHz are applied to an interior electrode to both ignite and sustain the plasma between electrodes. The outer slotted electrode is grounded. Illustrative absolute emission of optical spectra from this source is presented in the region from 100 to 400 nm as well as total oxygen radical fluxes from the source. We present both RF breakdown and sustaining voltage measurements as well as impedance values measured for the microplasmas, which use flowing rare gas in the interelectrode region exiting into open air. The requirement for rare gas flow is necessary to get uniform plasmas of dimensions over 30 cm, but is a practical disadvantage. In one mode of operation we create an out-flowing afterglow plasma plume, which extends 1-3 mm from the grounded open slot allowing for treatment of work pieces placed millimetres away from the grounded electrode. This afterglow configuration also allows for lower gas temperatures impinging on substrates, than the use of active plasmas. Work pieces are not required to be part of any electrical circuit, bringing additional practical advantages. We present a crude lumped parameter equivalent circuit model to analyse the effects of changing RF sheaths with frequency of excitation and applied RF current to better understand the relative roles of sheath and bulk plasma behaviour observed in electrical characteristics. Estimates of the bulk plasma densities are also provided. Finally, we present results of afterglow plasma based bacteria inactivation studies (Escherichia coli, Bacillus atrophaeus and B. atrophaeus spores) in which we employ the flowing afterglow plume from a hollow slot microplasma device rather than the active plasma itself, which is fully contained between electrodes.

Rahul, R.; Stan, O.; Rahman, A.; Littlefield, E.; Hoshimiya, K.; Yalin, A. P.; Sharma, A.; Pruden, A.; Moore, C. A.; Yu, Z.; Collins, G. J.

2005-06-01

329

Physical characteristics of GE (General Electric) BWR (boiling-water reactor) fuel assemblies  

SciTech Connect

The physical characteristics of fuel assemblies manufactured by the General Electric Company for boiling-water reactors are classified and described. The classification into assembly types is based on the GE reactor product line, the Characteristics Data Base (CDB) assembly class, and the GE fuel design. Thirty production assembly types are identified. Detailed physical data are presented for each assembly type in an appendix. Descriptions of special (nonstandard) fuels are also reported. 52 refs., 1 fig., 6 tabs.

Moore, R.S.; Notz, K.J.

1989-06-01

330

Electrical Characteristics of Thin-Film Transistors with Double-Active-Layer Structure  

Microsoft Academic Search

Thin-film transistors (TFTs) with a double-active-layer (DAL) structure have been proposed and found to exhibit two kinds of special electrical characteristics. One is the improvement of current drivability and transconductance as compared to the traditional structure. The other is the double-switching characteristics caused by the bi-transistor action. By means of a buried oxide separating the conduction channel into two parts,

Meng-Jin Tsai; Ping-Wei Wang; Huan-Ping Su; Huang-Chung Cheng

1995-01-01

331

Characteristics of China’s coal, oil and electricity price and its regulation effect on entity economy  

Microsoft Academic Search

Price of coal, electricity and oil are key factors affecting economy. Taking the yearly data of 1980-2007 as a sample, we tested the fluctuation characteristics and causality of coal, electricity and oil price, and indicated that there is dual-causality between the coal and electricity price. Through Cointegration test and State Space Model, effect of coal, electricity, oil price on output

He Ling-yun; Li Yan

2009-01-01

332

Thermal breakdown of ZnTe nanowires.  

PubMed

As the applications for inorganic nanowires continuously grow, studies on the stability of these structures under high electrical/thermal stress conditions are needed. ZnTe nanowires are grown by the vapor-liquid-solid technique and their breakdown under Joule heating is studied through in situ monitoring in a transmission electron microscope (TEM). The experimental setup, consisting of a scanning tunneling microscope (STM) and a movable piezotube inside the TEM, allows the manipulation of a single nanowire. A voltage applied to the STM tip in contact with a ZnTe nanowire leads to the breakdown of the nanowire into Zn and Te particles or balls which is observed in real time. These balls grow by Ostwald ripening, rendering the surface morphology of the ZnTe nanowire progressively rough. Diffraction patterns along the stem of the wire after the partial breakdown showed substantially smaller lattice spacing compared to 0.35 nm for pristine ZnTe nanowires. PMID:22131283

Davami, Keivan; Ghassemi, Hessam M; Yassar, Reza S; Lee, Jeong-Soo; Meyyappan, M

2012-01-16

333

Dielectric breakdown strength of GFRPs under mechanical stresses in cryogenic liquids  

Microsoft Academic Search

The dielectric strength of GFRPs (glass-fiber-reinforced plastics) under combined application of electrical and mechanical stresses was investigated in liquid He, liquid N2, and silicone oil at room temperature. With the combined application of tensile and electrical stresses in cryogenic liquids, the dielectric breakdown of GFRPs occurred prior to mechanical breakdown when the applied electrical stress was lower than the DBS

K. Fukushi; M. Nagai; Y. Kamata

1989-01-01

334

Electrical characteristics of the back-gated bottom-up silicon nanowire field effect transistor  

Microsoft Academic Search

We report electrical characteristics of back-gated silicon nanowire field effect transistors (SNWFETs) fabricated using silicon nanowires synthesized by a standard vapor-liquid-solid process. It is shown that the mobilities obtained from the measured transconductances are reasonable only when the nanowire is fully depleted.

DukSoo Kim; YoungChai Jung; MiYoung Park; ByungSung Kim; SuHeon Hong; MinSu Choi; MyungGil Kang; YunSeop Yu; DongMok Whang; SungWoo Hwang

2008-01-01

335

Correlation of electrical and optical characteristics of selectively oxidized vertical-cavity surface-emitting lasers  

SciTech Connect

We investigate the correlation between the electrical and optical characteristics of selectively oxidized vertical-cavity surface-emitting lasers (VCSELs). Electrical derivative analysis is used on VCSELs to study the electrical performance and its correlation with the polarization-resolved optical powers and spectra. Characteristic features are shown in the IdV/dI curves near major transition points of VCSEL operation. From the IdV/dI curve we are able to precisely identify important operating currents such as the lasing threshold, the higher-order mode lasing current, and the cut-off current. Five operation regions are defined in the polarization-resolved L{minus}I curves based on these currents and their temperature dependences are also studied. {copyright} {ital 1997 American Institute of Physics.}

Li, J.; Seurin, J.; Chuang, S.L. [Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)] [Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Choquette, K.D.; Geib, K.M.; Hou, H.Q. [Center for Compound Semiconductor Technology, Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)] [Center for Compound Semiconductor Technology, Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)

1997-04-01

336

Nondestructive microstructural diagnostic of integrated ferroelectric capacitor arrays: Correlation with electrical characteristics  

NASA Astrophysics Data System (ADS)

Considering the critical role of the storage capacitor on the reliability of ferroelectric random access memories (FeRAM), it is of particular interest to analyze the electrical and microstructural characteristics of the ferroelectric capacitor after the integration steps. In addition to standard electrical testing, the architecture of memory cell arrays in 0.35 ?m complementary metal-oxide-semiconductor (CMOS) technology was characterized using an original approach combining microfocused synchrotron x-ray fluorescence and diffraction. A 1.5 kbyte FeRAM memory block was scanned with a step size of 0.2 ?m while simultaneously acquiring fluorescence spectra and diffraction patterns in order to obtain, respectively, chemical and crystallographic mapping of the thin films constituting the memory cell. The excellent agreement observed between measured data and memory cell design explains the good electrical characteristics of the analyzed FeRAM chips.

Muller, Ch.; Menou, N.; Barrett, R.; Save, D.

2006-03-01

337

Beauty in the Breakdown  

ERIC Educational Resources Information Center

Most human beings look at erosion as the destruction of a surface, but artists can see that erosion often creates indefinable beauty. Where do you see beauty in the breakdown? In this article, the author presents an innovative lesson that would allow students to observe both human and physical nature. In this activity students will create a work…

Brisco, Nicole

2008-01-01

338

Strength characteristics of the shafts of series PED submersible electric motors  

SciTech Connect

The development of reliable and long-operating electrical machinery, increasing its service qualities, and a reduction in weight all require that in design and production an electric motor be considered as a mechanical system operating under complex dynamic conditions. This paper reports on studies conducted on the shafts of series PED submersible electric motors, with the following conclusions: a groove as a stress raiser exerts a significant influence on the strength characteristics of the shaft, the influence varying with shaft diameter; structural investigations of the fracture surface of specimens indicate significant changes in original structure during plastic deformation and fracture, the area of intense plastic deformation being wider in grooved specimens; the high-strength vanadium-bearing steels, 28KhGN3FE and 40Kh2N2AFE, with high mechanical properties were developed and produced and the former is recommended for the production of submersible electric motor shafts.

Reznikov, V.D.; Bogomolov, S.I.; Khodos, L.S.; Kurilov, G.V.; Panfilova, L.M.

1985-10-01

339

Depressed DC Breakdown Phenomena near Curie Temperature of BaTiO3Based Ceramic Capacitors  

Microsoft Academic Search

In this paper, temperature-dependent dc breakdown in BaTiO3-based multilayer ceramic capacitors (MLCs) is studied. We measured dc breakdown fields (BDFs) at temperatures ranging from room temperature to 250°C. According to the change in the breakdown characteristics with temperature, the breakdown process can be regarded as consisting of three regions: room, Curie and high temperature regions. An abnormal depressed BDF was

Yuanxiang Zhou; Ping Yan; Noboru Yoshimura; Zixia Cheng; Xidong Liang; Zhicheng Guan

2001-01-01

340

The Effect of Mechanical Hardness on RF Breakdown  

SciTech Connect

Preliminary high-energy tests have been performed on the next linear collider test accelerator and the traveling wave structures have been examined with a scanning electron microscope. This has yielded the locations of radio frequency breakdowns, characterized by surface craters, occurring on the oxygen-free electric copper traveling wave structure. It has been proposed that the occurrence of high voltage breakdown may be related to material hardness. We have examined this possibility by measuring the hardness of various crystal grains within the copper structure and searching for any correlations to the breakdown events. The hardness of various copper crystals grains has been measured with a nano-indenter and the crystal grains have subsequently been analyzed for breakdown damage. This preliminary analysis does not show any explicit indications that mechanical hardness may be related on the occurrence of RF breakdown. Further research is suggested to verify these initial results.

Adamson, Kristi

2003-09-05

341

The prevention of electrical breakdown and electrostatic voltage problems in the space shuttle and its payloads. Part 1: Theory and phenomena  

NASA Technical Reports Server (NTRS)

An introduction to the theory of corona discharge and electrostatic phenomena is presented. The theory is mainly qualitative so that workers in the field should not have to go outside this manual for an understanding of the relevant phenomena. Some of the problems that may occur with the space shuttle in regard to electrical discharge are discussed.

Whitson, D. W.

1975-01-01

342

Electrical characteristics of Ni Ohmic contact on n-type GeSn  

NASA Astrophysics Data System (ADS)

We report an investigation of the electrical and material characteristics of Ni on an n-type GeSn film under thermal annealing. The current-voltage traces measured with the transmission line method are linear for a wide range of annealing temperatures. The specific contact resistivity was found to decrease with increasing annealing temperature, followed by an increase as the annealing temperature further increased, with a minimum value at an annealing temperature of 350 °C. The material characteristics at the interface layer were measured by energy-dispersive spectrometer, showing that an atomic ratio of (Ni)/(GeSn) = 1:1 yields the lowest specific contact resistivity.

Li, H.; Cheng, H. H.; Lee, L. C.; Lee, C. P.; Su, L. H.; Suen, Y. W.

2014-06-01

343

Plasma etched polycrystalline hot-filament chemical vapor deposited diamond thin films and their electrical characteristics  

SciTech Connect

Etching of hot-filament, chemical vapor deposited, diamond thin films utilizing low energy ion irradiation was investigated. The films used in this study were boron doped polycrystalline diamond, deposited on [ital p]-type (100) oriented silicon substrates. A low voltage dc corona discharge with an oxygen plasma was used to sputter etch the films. Surfaces were investigated by scanning electron microscopy and profilometry. Etch rates were approximately 500 A/min, depending on the various processing conditions. Characteristics of In/diamond/Si Schottky diodes were used to evaluate the electrical properties of diamond surfaces with various treatments. Results indicate that plasma etching can significantly affect Schottky device characteristic.

Liaw, B.Y.; Stacy, T.; Zhao, G.; Charlson, E.J.; Charlson, E.M.; Meese, J.M.; Prelas, M.A. (College of Engineering, University of Missouri, Columbia, Missouri 65211 (United States))

1994-11-28

344

Mechanical characteristics of strained vibrating strings and a vibration-induced electric field  

NASA Astrophysics Data System (ADS)

The mechanical characteristics of vibrating strings strained between rigid supports and a vibration-induced electric field are studied. Experiments are conducted with nylon, rubber, and metallic strings. Vibrations are excited by a pinch at different sites along the string. The motion of the string is filmed, and the attendant electric field is detected. Experimental data are analyzed under the assumption that the field is induced by unlike charges generated by the moving string. It is found that the field allows one to determine the time characteristics of the motion of the string and discriminate the types of its deformations. Young moduli observed under the static extension of thin nylon strings are compared with those calculated from the natural frequencies of vibration measured for differently strained strings. The mathematical pattern of the motion of the string is compared with the real situation.

Bivin, Yu. K.

2012-11-01

345

Propagation characteristics of surface acoustic waves in single-electron transport devices and the electrical measurement.  

PubMed

We focused on investigating the propagation characteristics of surface acoustic waves (SAWs) in SAW-based single-electron-transport (SAW/SET) devices. SAW/SET devices operating in the gigahertz frequency range were fabricated on a GaAs/Al(x)Ga(1-x)As heterostructure. The transmittance and reflection performances of SAW/SET devices were obtained via the electrical measurement. Modeling based on coupling-of-modes theory was introduced to analyze SAW/ SET devices. Based on this model, many second-order effects such as propagation loss and the mechanical and electrical loadings caused by electrode perturbation of the surface were taken into account. Multiple-transit reflections of SAWs were also contained in the calculation. The calculated transmittance and reflection performances were in good agreement with the measured data. Furthermore, we proposed four interference types which could satisfactorily explain the periodic oscillations presented in the acoustoelectric current versus frequency characteristics. PMID:21768029

Zhang, Chuan-Yu; Gao, Jie; Li, Hong; Song, Li; Lu, Chuan

2011-07-01

346

Discharge characteristics under non-uniform electric field in He, Ar and air at low pressures  

Microsoft Academic Search

We measured dc discharge inception voltage Vi for various electrode configurations in He, Ar and air in vacuum range from 105 to 10-1 Pa to determine discharge characteristics under a space vacuum environment. By quantitative consideration of the Ei\\/p distribution in the gap space at the discharge inception, the discharge inception mechanism under non-uniform electric field was investigated in vacuum.

H. Okubo; S. Yuasa; K. Ota; N. Hayakawa; M. Hikita

1997-01-01

347

Electrical characteristics of directly-bonded GaAs and InP  

Microsoft Academic Search

The electrical characteristics of directly bonded GaAs\\/InP heterointerfaces have been investigated for the first time. The mirror-polished surfaces of GaAs and InP wafers were put face to face and bonded by heat treatment at temperatures ranging from 450 to 700 °C. The wafers were successfully bonded without using any solders at all the temperatures tested. 1.3 ?m InP\\/GaInAsP lasers were

Hiroshi Wada; Yoh Ogawa; Takeshi Kamijoh

1993-01-01

348

Analysis of the sensitivity and frequency characteristics of coplanar electrical cell–substrate impedance sensors  

Microsoft Academic Search

A PDMS-glass based micro-device was designed and fabricated with 12 coplanar impedance sensors integrated for electrical cell–substrate impedance sensing (ECIS). The sensitivity and frequency characteristics of the sensors were investigated both theoretically (equivalent circuit model) and experimentally for the commonly used micro-electrode dimension scale (20–80?m). The experimental results matched well with the theoretical model analysis and revealed that, within this

Lei Wang; He Wang; Keith Mitchelson; Zhongyao Yu; Jing Cheng

2008-01-01

349

Differential topological characteristics of the DSR on injection space of electrical power system  

Microsoft Academic Search

This paper analyzes the differential topological characteristics of the dynamic security region (DSR) on injection space of\\u000a electrical power system by differential topology theories. It is shown that the boundary of the DSR on injection space has\\u000a no suspension and is compact, and there are no holes inside the DSR defined based on controlling unstable equilibrium point\\u000a (UEP) method. The

Yixin Yu; Yuan Zeng; Fei Feng

2002-01-01

350

Electrical and charge storage characteristics of the tantalum oxide-silicon dioxide device  

Microsoft Academic Search

The electrical characteristics of the tantalum oxide-silicon dioxide double-dielectric structure are described. The MTOS structure (metal-tantalum oxide-silicon dioxide-silicon) is similar to the MNOS double dielectric which is used as a nonvolatile memory element except tantalum oxide (Ta2O5) is used to replace the silicon nitride as the second dielectric. Capacitance voltage measurements show a negative QSSwith magnitudes smaller than those in

R. L. Angle; H. E. Talley

1978-01-01

351

Effect of surface inhomogeneities on the electrical characteristics of SiC Schottky contacts  

Microsoft Academic Search

This paper reports analysis of the role of defects on the electrical characteristics of high-voltage 6H-SiC Schottky rectifiers. The measured reverse leakage current of high-voltage Ti and Pt rectifiers was found to be much higher than that predicted by thermionic emission theory and using a barrier height extracted from the C-V measurements. In this paper, a model based upon the

Mohit Bhatnagar; B. Jayant Baliga; H. R. Kirk; G. A. Rozgonyi

1996-01-01

352

Electrical Characteristics and Interface Structure of Hafnium Oxyfluoride barrier in Magnetic Tunnel Junctions  

Microsoft Academic Search

We have studied effects of fluorine inclusion on electrical transport characteristics and interface structures of the hafnium oxide barrier in magnetic tunnel junction. The tunneling magnetoresistance (TMR) and resistance-area (RA) as a function of oxidation time show that the TMR ratio of the hafnium oxyfluoride barrier is higher (8.3%) than that of the halfnium oxide barrier (5.7%) at their optimum

Yuyeon Yu; Daeshik Kim; Junghyun Hahm; Kookrin Char

2004-01-01

353

Electrical characteristics and interface structure of magnetic tunnel junctions with hafnium oxyfluoride barrier  

Microsoft Academic Search

We have studied the effects of fluorine inclusion on the electrical transport characteristics and interface structure of the hafnium oxide barrier in a magnetic tunnel junction. The tunneling magnetoresistance (TMR) and resistance-area (RA) as a function of oxidation time show that the TMR ratio of the hafnium oxyfluoride barrier is higher (8.3%) than that of the hafnium oxide barrier (5.7%)

Y. Y. Yu; D. S. Kim; K. Char

2004-01-01

354

In vivo electrical characteristics of human skin, including at biological active points  

Microsoft Academic Search

The aim is to compare the mean values of the in vivo electrical characteristics of bioiogical active points (BAPs) with those\\u000a of the surrounding human skin. The impedance measurements at BAPs and on the surrounding skin are carried out in vivo on ten\\u000a young, healthy people. The results of the measurements show that the BAP resistance RP is smaller, and

E. F. Prokhorov; J. González-Hernández; Y. V. Vorobiev; E. Morales-Sánchez; T. E. Prokhorova; G. Zaldivar Lelo de Larrea

2000-01-01

355

Electrical properties of a commercial resin  

SciTech Connect

The aim of this study is to present electrical properties of a commercial resin. We report our findings on its dielectric and electrical breakdown characteristics. Dielectric measurements are performed by using the frequencyand time-domain impedance techniques at room temperature. Impedance data is analyzed with the distribution of relaxation times approach, which point-out individual polarization processes in a material. In addition, curing procedure is monitored with the impedance spectroscopy technique.

Tuncer, Enis [ORNL; Sauers, Isidor [ORNL; James, David Randy [ORNL; Ellis, Alvin R [ORNL

2006-01-01

356

Analysis of the electrical characteristics and structure of Cu-Filled TSV with thermal shock test  

NASA Astrophysics Data System (ADS)

The electrical characteristics and failure of a Through-Silicon Via (TSV) were investigated using a thermal shock test. The electrical characteristics, such as resistance ( R), self-inductance ( L s ), self-capacitance ( C s ), and mutual capacitance ( C m ), were extracted using a T-equivalent circuit. A cross section of the Cu-filled via was observed by field emission-scanning electron microscopy and the electrical characteristics were measured using a commercial Agilent E4980A LCR Meter. The experimental results revealed R, L s , C s , and C m values of 3.2 m?, 29.3 pH, 12 fF, and 0.42 pF, respectively. C m occurred between the charge-holding TSVs, which changed from 0.42 pF to 0.26 pF due to a permittivity transition of the Cu ion drift. After 1,000 cycles of a thermal shock test, cracks were observed between the opening and around the side of the TSV and Si wafer due to mismatch of the coefficient of thermal expansion between the Cu-plug and Si substrate.

Jeong, Il Ho; Roh, Myong Hoon; Jung, Flora; Song, Wan Ho; Mayer, Michael; Jung, Jae Pil

2014-05-01

357

Electrical characteristics of an electrostatic valve used for bulk transport of agricultural seeds  

SciTech Connect

In an electrostatic valve used for bulk transport of agricultural seeds, the interparticulate electroclamping forces can be established by applying electric potential gradient between a separated pair of conducting electrode grids placed perpendicularly across the flow. The flow control of particulate material is thus achieved using no moving parts. When an electric field is applied, several types of electric field forces are generated, depending on the bulk and surface resistivities of the particles, the geometry of the electrodes, the applied field, and the geometry and the conductivity of the materials used for the transport channel. In this study the current-voltage characteristics of the valve were experimentally investigated for different flow control parameters. The triboelectrification of turnip seeds caused by the frictional contact on the channel walls was investigated and compared with the valve current. A range of wall liner materials with different electrical properties conductive to insulating were tested. The materials used for the wall liner did not significantly influence the current characteristics of the electrostatic valve. The effect of pulse duration of the applied potential on charge-to-mass ratio of the level of net charge acquired by the particles could be controlled by controlling the duty cycle of the electroclamping field.

Balachandran, W.; Machowski, W. [Brunel Univ., Uxbridge (United Kingdom). Dept. of Mfg. and Engineering Systems] [Brunel Univ., Uxbridge (United Kingdom). Dept. of Mfg. and Engineering Systems; Thompson, S.A.; Law, S.E. [Univ. of Georgia, Athens, GA (United States). Dept. of Biological and Agricultural Engineering] [Univ. of Georgia, Athens, GA (United States). Dept. of Biological and Agricultural Engineering

1999-03-01

358

Breakdown in rf cavities.  

SciTech Connect

We present a simple model of breakdown in rf cavities. For most events this involves tensile stress and tensile strength, however other effects can also contribute. We discuss the effects of different materials, fatigue, high pressure gas, primary and secondary emission sites, local field enhancements, dark currents, secondary emission, work functions, magnetic fields, macro and microscopic fracture mechanisms high current densities, surface and subsurface defects, and astronomical power densities. While primarily devoted to normal conductors, this work also has consequences for superconducting rf surfaces.

Norem, J.; Hassanein, A.; Insepov, Z.; Konkashbaev, I.

2005-01-01

359

The Explanation of the Photon's Electric and Magnetic Fields; and its Particle and Wave Characteristics  

NASA Astrophysics Data System (ADS)

Using the principles of the Vortex Theory, the creation of the photon's electric and magnetic components are explained: the condensed region of space is responsible for creating the photon's electric component and its particle effect; its expansion and contraction is responsible for its frequency; its motion through three dimensional space creates a wave in the surrounding space. This wave is responsible for the photon's magnetic component and wave characteristics. The simultaneous expansion and contraction of both the dense region of space that is the photon and the surrounding space it passes through explains why the electric and magnetic effects are at right angles to each other. Also the photon's particle and wave characteristics are explained. 1.Russell Moon, The Bases of the Vortex Theory of Space. Publishing house of ZNAK, Moscow, Russia, 2002, 32 pp., (in Russian). 2 R.G. Moon, The Possible Existence of a New Particle: the Neutral Pentaquark? Book of materials, The Research Centre of Ecological Safety of the Russian Academy of Sciences: Scientific Seminar 0f Ecology and Space 1, February 22, 2005, Saint-Petersburg, Russia, 2005, pp. 98-104.

Moon, Russell; Vasiliev, Victor

2007-10-01

360

The Explanation of the Photon's Electric and Magnetic Fields; and its Particle and Wave Characteristics  

NASA Astrophysics Data System (ADS)

Using the principles of the Vortex Theory, the creation of the photon's electric and magnetic components are explained: the condensed region of space is responsible for creating the photon's electric component and its particle effect; its expansion and contraction is responsible for its frequency; its motion through three dimensional space creates a wave in the surrounding space. This wave is responsible for the photon's magnetic component and wave characteristics. The simultaneous expansion and contraction of both the dense region of space that is the photon and the surrounding space it passes through explains why the electric and magnetic effects are at right angles to each other. Also the photon's particle and wave characteristics are explained. 1.Russell Moon, The Bases of the Vortex Theory of Space. Publishing house of ZNAK, Moscow, Russia, 2002, 32 pp., (in Russian). 2 R.G. Moon, The Possible Existence of a New Particle: the Neutral Pentaquark? Book of materials, The Research Centre of Ecological Safety of the Russian Academy of Sciences: Scientific Seminar 0f Ecology and Space 1, February 22, 2005, Saint-Petersburg, Russia, 2005, pp. 98-104.

Moon, Russell; Vasiliev, Victor

2007-11-01

361

Physical and electrical characteristics of metal/Dy2O3/p-GaAs structure  

NASA Astrophysics Data System (ADS)

This paper describes the effect of post-deposition annealing on the physical and electrical characteristics of high-k Dy2O3 dielectric films deposited at 250 °C on p-GaAs substrate by electron beam deposition under ultra vacuum. The morphological and structural features of Dy2O3 layer before and after postdeposition annealing were studied by atomic force microscopy (AFM) and X-ray diffraction (XRD). The surface topography analysis reveals that the Dy2O3 film is granular, and contains numerous contacts between columnar grains. While investigating the electrical properties Dy2O3 oxide, the current-voltage characteristics I(V) suggest a Poole-Frenkel (PF) type mechanism of carrier transport for as-deposited and annealed layers. A deviation from the PF leakage current course was found and attributed to the current carrier trapping. The ac impedance properties of the structures have been studied in a wide frequency range at different bias voltage. The Dy2O3 annealed exhibited excellent electrical properties such as small density of interface state and low leakage current. This phenomenon is attributed to a rather crystallized Dy2O3 structure and the reduction of the defects at the oxide/GaAs interface.

Saghrouni, H.; Jomni, S.; Belgacem, W.; Hamdaoui, N.; Beji, L.

362

Breakdown of the high-voltage sheath in metal plasma immersion ion implantation  

SciTech Connect

It is suggested that breakdown of a space-charge sheath obeys similar breakdown laws as known for vacuum breakdown. When metal plasmas of vacuum arcs are used, the sheath between a biased substrate and plasma is very thin and the electric-field strength is very high. Field enhancement (e.g., at sharp edges of the substrate) leads to thermal instability of electron emission centers, followed by dense plasma formation which, in turn, electrically short circuits the sheath (breakdown). Theoretical and experimental evidence for this mechanism is presented. (c) 2000 American Institute of Physics.

Anders, Andre [Lawrence Berkeley National Laboratory, University of California at Berkeley, Berkeley, California 94720 (United States)] [Lawrence Berkeley National Laboratory, University of California at Berkeley, Berkeley, California 94720 (United States)

2000-01-03

363

Breakdown of model aircraft radome dielectric shell in artificial charged aerosol clouds  

NASA Astrophysics Data System (ADS)

The breakdown of a model aircraft radome dielectric shell in artificial charged aqueous aerosol clouds has been experimentally studied. It is established that, in most cases, electric breakdown of a model shell takes place without explicit discharge development between a charged aqueous aerosol cloud and a model antenna arranged under the radome shell. The probabilities of the dielectric shell breakdown have been determined for various radome models. A possible mechanism of the shell breakdown in hollow dielectric radomes interacting with charged aqueous aerosol clouds and electric discharges in these clouds is proposed that takes into account the accumulation of charges of opposite signs on the internal and external surface of the radome.

Temnikov, A. G.; Chernenskii, L. L.; Orlov, A. V.; Antonenko, S. S.

2011-10-01

364

Optical measurements for interfacial conduction and breakdown  

NASA Astrophysics Data System (ADS)

Measurements and calculations contributing to the understanding of space and surface charges in practical insulation systems are given. Calculations are presented which indicate the size of charge densities necessary to appreciably modify the electric field from what would be calculated from geometrical considerations alone. Experimental data is also presented which locates the breakdown in an electrode system with a paper sample bridging the gap between the electrodes. It is found that with careful handling, the breakdown does not necessarily occur along the interface even if heavily contaminated oil is used. The effects of space charge in the bulk liquid are electro-optically examined in nitrobenzene and transformer oil. Several levels of contamination in transformer oil are investigated. Whereas much space charge can be observed in nitrobenzene, very little space charge, if any, can be observed in the transformer oil samples even at temperatures near 100 degrees C.

Hebner, R. E., Jr.; Kelley, E. F.; Hagler, J. N.

1983-01-01

365

Effect of Electrostatic Discharge on Electrical Characteristics of Discrete Electronic Components  

NASA Technical Reports Server (NTRS)

This article reports on preliminary results of a study conducted to examine how temporary electrical overstress seed fault conditions in discrete power electronic components that cannot be detected with reliability tests but impact longevity of the device. These defects do not result in formal parametric failures per datasheet specifications, but result in substantial change in the electrical characteristics when compared with pristine device parameters. Tests were carried out on commercially available 600V IGBT devices using transmission line pulse (TLP) and system level ESD stress. It was hypothesized that the ESD causes local damage during the ESD discharge which may greatly accelerate degradation mechanisms and thus reduce the life of the components. This hypothesis was explored in simulation studies where different types of damage were imposed to different parts of the device. Experimental results agree qualitatively with the simulation for a number of tests which will motivate more in-depth modeling of the damage.

Wysocki, Phil; Vashchenko, Vladislav; Celaya, Jose; Saha, Sankalita; Goebel, Kai

2009-01-01

366

Further statistical studies of ionization growth and breakdown formation mechanisms in the final breakdown phase of a transient hollow cathode discharge  

Microsoft Academic Search

A transient hollow cathode discharge (THCD) is a high-voltage low-pressure discharge, which is characterized by an axial hollow in the cathode electrode. The temporal sequence of the different parts of ionization growth in breakdown formation, which take place just before electric breakdown, are statistically studied. The von Lane formalism has been used to characterize in detail the statistical time distribution

José Moreno; Marcelo Zambra; Mario Favre

2002-01-01

367

Electrical and dielectric characteristics of Al/Dy2O3/p-Si heterostructure  

NASA Astrophysics Data System (ADS)

In this work we report the electrical characteristics of high-k Dy2O3 dielectric deposited on p-Si substrate by electron beam deposition under ultra vacuum. The surface morphology of Dy2O3 is investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The surface topography analysis reveals that the Dy2O3 film is nanograined and contains numerous contacts between columnar grains. The electrical properties of Al/Dy2O3/p-Si heterostructure are further analyzed by current-voltage (I-V), capacitance-voltage (C-V), capacitance-frequency (C-f) and conductance-frequency (G-f) measurements. The dominant conduction mechanisms which governed the Al/Dy2O3/p-Si heterostrucure are determined. The hetrostructure induces a significant value of leakage current: 1.1×10-5 A at flat-band voltage -1 V which is linked to the structural properties of the elaborated structure. The effects of grain boundaries and oxygen vacancies within the dielectric are observed in term of leakage current. Indeed, the C(V) characteristics measured at different applied voltage show a large frequency-dispersion, indicative of the presence of a continuous distribution of interface states. So, the interface state densities are determined from the C(V) characteristics to be around 1013 eV-1 cm-2. C(f) measurements elucidate that the capacitance behavior is typical of material with traps. From G(f) and C(f) measurement the trap density and relaxation time are also determined. It is suggested that the interface states series resistance are important parameters that strongly influence the electrical properties of Al/Dy2O3/p-Si heterostrucure.

Cherif, Ahlem; Jomni, Sami; Mliki, Najeh; Beji, Lotfi

2013-11-01

368

Comparison of the electrical characteristics of liquid crystal cells with organic and inorganic alignment materials exposed to ion beam  

Microsoft Academic Search

A commercially available polyimide and two forms of diamond-like carbon films being ion beam exposure were used to figure out their effects on the electrical characteristics of the liquid crystal cell.

Bang-Hao Wu; Tsan-Yu Ho; Hsin-Chun Chiang; Ching-Wen Hsiao; Chun-Chin Chen; F. C.-N. Hong; Chia-Rong Sheu; Jian-Lung Chen

2004-01-01

369

Effect of configuration and dimensions of reactor electrodes on electrical and optical corona discharge characteristics  

SciTech Connect

An experimental parametric study is made to investigate how the electrical corona discharge characteristics are influenced by the geometrical configuration and dimensions of the reactor and the electrode polarity of the applied voltage. Furthermore, features of the corona discharge plasma formed around the stressed electrode in some different gases are recorded photographically to provide more information on the physical mechanisms of the corona discharge in the investigated gases. The obtained results have been discussed in the light of gas discharge physics and its applications.

El-Koramy, Reda Ahmed; Yehia, Ashraf; Omer, Mohamed [Department of Physics, Faculty of Science, Assiut University, 71516 Assiut (Egypt)

2010-05-15

370

Electrical and photovoltaic characteristics of sodium copper chlorophyllin\\/n-type silicon heterojunctions  

Microsoft Academic Search

Heterojunctions of p-type sodium copper chlorophyllin (p-SCC)\\/n-type silicon (n-Si) were prepared by deposition of p-SCC film on n-Si wafers using spray-pyrolysis technique. Current–voltage and capacitance–voltage measurements of Au\\/p-SCC\\/n-Si\\/In heterojunctions were performed to discuss the electrical properties of these heterostructures. Rectifying characteristics were observed, which are definitely of the diode type. The current–voltage measurements suggest that the forward current in these

A. A. M. Farag

2009-01-01

371

Electrical characteristics of postdeposition annealed HfO2 on silicon  

Microsoft Academic Search

Electrical characteristics of ultrathin HfO2 films on p-type silicon (100) substrates were determined by capacitance-voltage and current density-voltage measurements. The as-deposited HfO2 films showed a dielectric constant of ~22, a leakage current density of 5 A\\/cm2 and an interface state density of 6.5×1012 cm2 eV-1 at an equivalent oxide thickness (EOT) of 7.6 A˚ due to the poor quality of

Ragesh Puthenkovilakam; Monica Sawkar; Jane P. Chang

2005-01-01

372

Computer simulation for characteristics of a CCTS bistable DH laser with electric injection  

SciTech Connect

The computer simulation for stable characteristics and transient response of a CCTS bistable DH laser with electric injection is reported. The source of producing bistable behavior and self-pulsation is an intrinsic saturable absorber due to nonhomogeneous injection currents for this model. Some parameters which affect self-pulsation and bistability are investigated; these parameters with relation to a saturable absorber are the spontaneous emission factor, input normalized currents J/sub 1/, J/sub 2/ for gain, and absorbed sections, respectively.

Wang Qiming; Li Jianmeng

1989-01-01

373

Electrical Characteristics of Ultrasonic Nozzle Using Multilayer Ring-Type Piezoelectric Ceramics for Light Oil Spray  

Microsoft Academic Search

In this paper, ultrasonic nozzle and its driving circuit were manufactured. And then, their electrical properties were investigated. Ultrasonic nozzle using multilayer ring-type piezoelectric ceramics was fabricated by Pb[(Mn1\\/3Nb2\\/3)0.02(Ni1\\/3Nb2\\/3)0.12(Zr0.50Ti0.50)0.86]O3 (abbreviated as PMN-PNN-PZT) composition which have excellent piezoelectric characteristics. The multilayer ring-type piezoelectric ceramics using pure Ag inner electrode was sintered at 900°C low temperatures. In order to drive ultrasonic nozzle,

Jinhee Kang; Yuhyong Lee; Larkhoon Hwang; Juhyun Yoo; Jaeil Hong

2010-01-01

374

Electrical transport characteristics of DNA wrapped carbon nanotubes contacted to palladium and palladium oxide electrodes.  

SciTech Connect

DNA-wrapped carbon nanotubes (DNA-CNT) have generated attention due the ability to disperse cleanly into solution, and by the possibility of sorting nanotubes according to size and conductivity. In order to learn more about the effects of DNA on the electrical transport characteristics of single wall carbon nanotubes, we fabricate and test a series of devices consisting of DNA-wrapped CNTs placed across gold, palladium, and palladium oxide electrodes. In addition, we look at how DNA functionalized CNTs react to presence of hydrogen, which has previously been shown to affect the conductivity of CNTs when in contact with palladium.

Dentinger, Paul M.; Leonard, Francois; Jones, Frank Eugene; Talin, Albert Alec

2005-03-01

375

A breakdown model for the bipolar transistor to be used with circuit simulators  

SciTech Connect

A breakdown model for the output characteristics of the bipolar transistor (bjt) has been developed. The behavioral modeling capability of PSPICE, a popular SPICE program (with Emphasis on Integrated circuits) was used to implement the macromodel. The model predicts bjt output characteristics under breakdown conditions. Experimental data was obtained to verify the macromodel. Good agreement exits between the measured and the simulated results.

Keshavarz, A.A. [Alliance Technologies, Inc., Albuquerque, NM (United States); Raney, C.W.; Campbell, D.C. [Sandia National Labs., Albuquerque, NM (United States)

1993-08-01

376

Electrical and reliability characteristics of ultrathin oxynitride gate dielectric prepared by rapid thermal processing in N2O  

Microsoft Academic Search

The electrical and physical characteristics of oxynitride grown in N2O gas ambient have been studied. The dielectric growth rate in N2O was found to be highly controllable and lower than that in O2. Auger electron spectroscopy studies of oxynitride show a nitrogen-rich layer near the Si-SiO2 interface. Compared with the control oxide, the oxynitride shows excellent electrical characteristics such as

H. Hwang; W. Ting; D.-L. Kwong; J. Lee

1990-01-01

377

A study of the effect of plasma rotation on the characteristics of a high-power electric arc  

Microsoft Academic Search

The effect of plasma rotation on the electrical and power characteristics of a high-power self-compressed argon arc has been investigated numerically. It is shown that plasma rotation leads to an increase in the intensity of an electric field applied to the arc. The volt-ampere characteristic of the rotating arc increases monotonically in the region corresponding to superheat instability; i.e., plasma

K. D. Cher

1981-01-01

378

Study and modeling of the breakdown voltage in semi insulating GaAs P+N, PN+, P+N+ junctions diodes presenting deep centers traps  

NASA Astrophysics Data System (ADS)

This work aims at determining the characteristic I (Breakdown voltage) of the inverse current in GaAs PN junction diode, subject to an reverse polarization while specifying the parameters that influence the Breakdown voltage of the diodes. In this work, we simulated the behavior of the ionization phenomenon by impact Breakdown by avalanche of the PN junctions, subject to an inverse polarization. Will be taken into account both the trapping model in a stationary regime in the P+N, PN+, and P+N+ structures using like material of basis the III-V compounds and mainly the GaAs semi-insulating in which the deep centers have in important densities. The study of the physical and electric behavior of the semiconductors, and notably is based on the influence of the deep center presence on the characteristic I(V) current-tension, that requires calculation the electrostatic potential, the electric field, the integral of ionization, the density of the states traps, the diffusion current of minority in the regions (1) and (3), the current thermal generation in the region (2), the leakage current in surface, and the breakdown voltage.

Resfa, A.; Menezla, Brahimi R.; Bougueneya, Mustapha

2014-08-01

379

Land-ocean contrast on electrical characteristics of lightning discharge derived from satellite optical measurements  

NASA Astrophysics Data System (ADS)

Comparative studies on the electrical properties of oceanic and continental lightning are crucial to elucidate air discharge processes occurring under different conditions. Past studies however have primarily focused on continental lightning because of the limited coverage of ground-based instruments. Recent satellite measurements by FORMOSAT-2/ISUAL provided a new way to survey the global characteristics of lightning and transient luminous events regardless of land and ocean. In this study, we analyze ISUAL/spectrophotometer data to clarify the electrical properties of lightning on a global level. Based on the results obtained by Cummer et al. [2006] and Adachi et al. [2009], the OI-777.4nm emission intensity is used to infer lightning electrical parameters. Results show a clear land-ocean contrast on the parameters of lightning discharge: in oceanic lightning, peak luminosity is 60 % higher and the time scale of return stroke is 30 % shorter. These results suggest higher peak current in oceanic lightning, which is consistent with the fact that elves, EMP-driven phenomena, also tend to occur over the ocean [Chen et al., 2008]. Further analysis of lightning events occurring around the Caribbean Sea shows that the transition-line of lightning electrical properties is precisely located along the coastline. We suggest that the differences in these electrical properties may be due to the boundary conditions (conductivity, surface terrain, etc). In this talk, based on the calibration with NLDN and Duke magnetometer data, current moment change and charge moment change will be globally evaluated using a complete set of the ISUAL-observed lightning events.

Adachi, T.; Said, R.; Cummer, S. A.; Li, J.; Takahashi, Y.; Hsu, R.; Su, H.; Chen, A. B.; Mende, S. B.; Frey, H. U.

2010-12-01

380

Stable bipolar resistance switching behaviour induced by a soft breakdown process at the Al\\/La0.7Ca0.3MnO3 interface  

Microsoft Academic Search

The current-voltage characteristics, carrier transport processes and electric pulse induced resistance switching behaviour have been investigated in Al\\/La0.7Ca0.3MnO3 (LCMO)\\/Pt sandwich structures. A stable resistance switching effect was obtained when a soft breakdown process occurred during negative voltage sweeping. Moreover, the trigger condition of the high resistance state is completely different from that of the low resistance state. Based on the

R. Yang; X. M. Li; W. D. Yu; X. D. Gao; X. J. Liu; X. Cao; Q. Wang; L. D. Chen

2009-01-01

381

Modelling of time-dependent dielectric barrier breakdown mechanisms in MgO-based magnetic tunnel junctions  

NASA Astrophysics Data System (ADS)

An investigation of barrier endurance till electrical breakdown in MgO-based magnetic tunnel junctions (MTJs) is presented. Samples were tested under pulsed electrical stress. By studying the effect of delay between successive pulses, an optimum endurance of MTJs is observed for an intermediate value of delay between pulses corresponding to an optimum trade-off between the average density of charge trapped in the barrier and the amplitude of its time-modulation at each voltage pulse. A charge trapping-detrapping model was developed which shows good coherence with experimental results. The influence of the delay between pulses on the trapped charge density in the tunnel barrier and on its time-modulation is discussed. The average density of trapped charges and its time-modulation are, respectively, responsible for a static and dynamic stress within the tunnel barrier, both leading to breakdown. The probability of breakdown of the MTJ for different applied pulse conditions has been evaluated. The expected endurance of the MTJs was deduced depending on the characteristics of the electrical stress in terms of delay, and unipolarity versus bipolarity. The study emphasizes the role of electron trapping/detrapping mechanisms on the tunnel barrier reliability. It also shows that extremely long endurance could be obtained in MTJs by reducing the density of electron trapping sites in the tunnel barrier.

Amara-Dababi, S.; Bea, H.; Sousa, R.; Mackay, K.; Dieny, B.

2012-07-01

382

Electric Field Waveform Characteristics of Positive and Negative Lightning Return Strokes in Florida  

NASA Astrophysics Data System (ADS)

In 2007-2008, 52 positive cloud-to-ground flashes containing 63 return strokes (52 first, 10 second, and 1 third) were recorded at the Lightning Observatory in Gainesville (LOG), Florida. NLDN-reported distances from the LOG for 48 (40 first and 8 second) strokes ranged from 7.8 to 157 km. In this study, various microsecond-scale features of electric field waveforms of these positive return strokes including risetimes, characteristics of the slow-front and fast transition, zero-crossing time, opposite-polarity overshoot, and characteristics of the electric field derivative (dE/dt) pulse are examined and compared with the characteristics of negative return strokes in Florida found in the literature. Parameters of electric field waveforms produced by positive and negative first return strokes are summarized in Table 1. The AM zero-to-peak risetime and 10-90% risetime for 51 positive first return strokes were 7.9 ?s and 4.0 ?s, respectively, which are longer than the corresponding values of 4.4 ?s and 2.6 ?s for 105 first strokes in negative cloud-to-ground flashes in Florida reported by Master et al. (1984). The AM slow front duration for 51 positive first strokes was 6.1 ?s which is about a factor of two greater than that found for negative first return strokes by Master et al. For positive first return strokes examined here, the AM zero-crossing time was 58 ?s and the opposite polarity overshoot was, on average, 14% of the peak. These values are not much different from those (50 ?s and 19%) reported by Pavlick et al. (2002) for negative first return strokes in Florida. On the other hand, Haddad et al. (2012) reported the AM zero-crossing time of 96 ?s and the average opposite polarity overshoot of 23% for 48 negative first strokes recorded at the LOG at distances of 50 to 100 km. References: Haddad, M. A., V. A. Rakov et al. (2012), J. Geophys. Res., 117, D10101, doi:10.1029/2011JD017196. Krider, E. P., C. Leteinturier et al. (1996), J. Geophys. Res., 101(D1), 1589-1597. Master, M. J., M. A. Uman et al. (1984), IEEE Trans. PAS, PAS-103, pp. 2519-2529. Pavlick, A., D. E. Crawford et al. (2002), 7th International Conference on Probabilistic Methods Applied to Power Systems, Naples, Italy.Table 1. Parameters of electric field waveforms produced by positive and negative first return strokes in Floridat;

Nag, A.; Rakov, V. A.

2012-12-01

383

Electrical insulation design and withstand test of model coils for 6.6 kV class HTSFCL  

Microsoft Academic Search

Electrical design and withstand test of mini-model coils for high temperature superconducting fault current limiter (HTSFCL) have been studied. Electrical insulating factors of the HTS coil for HTSFCL are turn-to-turn and layer-to-layer. The electrical insulation of turn-to-turn depends on surface length, and the electrical insulation of layer-to-layer depends on surface length and breakdown strength of LN2. Therefore, two basic characteristics

Seung-Myeong Baek; Jong-Man Joung; Sang-Hyun Kim

2004-01-01

384

Electrical characteristics and reliability properties of metal-oxide-semiconductor field-effect transistors with Dy2O3 gate dielectric  

Microsoft Academic Search

Dy2O3 is a promising candidate for future metal-oxide-semiconductor (MOS) gate dielectric applications. In this work, MOS capacitors and field-effect transistors with Dy2O3 gate dielectric were fabricated. The maximum electron mobility was 339 cm2\\/V s. The time dependent dielectric breakdown (TDDB) of Dy2O3 as a function of electric field and temperature was studied. It was observed that the Weibull slopes were

Sheng-Chih Chang; Shao-You Deng; Joseph Ya-Min Lee

2006-01-01

385

The influence of dual-carrier recombination and release on electrical characteristics of pentacene-based ambipolar transistors  

NASA Astrophysics Data System (ADS)

Electrical characteristics of pentacene-based ambipolar organic field-effect transistors (OFETs) are examined and are shown to significantly differ from those of unipolar OFETs. The electrical and hysteresis characteristics of the ambipolar OFETs depend on the applied source-drain bias and sweeping gate voltage range. The ambipolar OFET characteristics, such as charge mobility, subthreshold swing, threshold voltage, and off-current level, are controlled by the dual-carrier recombination and release process, through which opposite-sign charges can capture and release majority charges. This study contributes to advancing the development of more applications based on ambipolar OFETs.

Chiu, Liang-Yun; Cheng, Horng-Long; Chou, Wei-Yang; Tang, Fu-Ching

2013-11-01

386

Effect of electrode surface roughness and dielectric coating on breakdown characteristics of high pressure CO2 and N2 in a quasi-uniform electric field  

Microsoft Academic Search

SF6 gas has excellent dielectric strength and interrupting capability and is used in various applications such as gas insulated switchgear (GIS) in substations. However, since SF6 has a high global warming potential (GWP), it is imperative to reduce its use and develop recovery technology for its reuse. This paper examined the potential of alternative insulating gases for GIS, determining experimentally

Masayuki Hikita; Shinya Ohtsuka; Nobuhiro Yokoyama; Shigemitsu Okabe; Shuhei Kaneko

2008-01-01

387

Runaway breakdown and hydrometeors in lightning initiation.  

PubMed

The particular electric pulse discharges are observed in thunderclouds during the initiation stage of negative cloud-to-ground lightning. The discharges are quite different from conventional streamers or leaders. A detailed analysis reveals that the shape of the pulses is determined by the runaway breakdown of air in the thundercloud electric field initiated by extensive atmospheric showers (RB-EAS). The high amplitude of the pulse electric current is due to the multiple microdischarges at hydrometeors stimulated and synchronized by the low-energy electrons generated in the RB-EAS process. The series of specific pulse discharges leads to charge reset from hydrometeors to the free ions and creates numerous stretched ion clusters, both positive and negative. As a result, a wide region in the thundercloud with a sufficiently high fractal ion conductivity is formed. The charge transport by ions plays a decisive role in the lightning leader preconditioning. PMID:23683210

Gurevich, A V; Karashtin, A N

2013-05-01

388

Runaway Breakdown and Hydrometeors in Lightning Initiation  

NASA Astrophysics Data System (ADS)

The particular electric pulse discharges are observed in thunderclouds during the initiation stage of negative cloud-to-ground lightning. The discharges are quite different from conventional streamers or leaders. A detailed analysis reveals that the shape of the pulses is determined by the runaway breakdown of air in the thundercloud electric field initiated by extensive atmospheric showers (RB-EAS). The high amplitude of the pulse electric current is due to the multiple microdischarges at hydrometeors stimulated and synchronized by the low-energy electrons generated in the RB-EAS process. The series of specific pulse discharges leads to charge reset from hydrometeors to the free ions and creates numerous stretched ion clusters, both positive and negative. As a result, a wide region in the thundercloud with a sufficiently high fractal ion conductivity is formed. The charge transport by ions plays a decisive role in the lightning leader preconditioning.

Gurevich, A. V.; Karashtin, A. N.

2013-05-01

389

Improved Model for MOS Breakdown  

NASA Technical Reports Server (NTRS)

With an improved model, accelerated high-field tests can be used to predict gate-oxide breakdown in metal-oxide-semi-conductor (MOS) structures. Principal mechanism in MOS breakdown is mobile-ion emission from metal/oxide interface, which occurs during application of positive gate-bias field. Breakdown is related to clustering of emitted ions at localized defect sites in oxide/silicon interface. Using new model to interpret data, tests that normally take several weeks at low fields to accumulate sufficient statistics can be completed in only a few hours at high fields.

Li, S. P.; Maserjian, J.

1982-01-01

390

Dielectric breakdown induced by picosecond laser pulses  

NASA Technical Reports Server (NTRS)

The damage thresholds of transparent optical materials were investigated. Single picosecond pulses at 1.06 microns, 0.53 microns and 0.35 microns were obtained from a mode locked Nd-YAG oscillator-amplifier-frequency multiplier system. The pulses were Gaussian in space and time and permitted the determination of breakdown thresholds with a reproducibility of 15%. It was shown that the breakdown thresholds are characteristic of the bulk material, which included nine alkali halides, five different laser host materials, KDP, quartz, sapphire and calcium fluoride. The extension of the damage data to the ultraviolet is significant, because some indication was obtained that two- and three-photon absorption processes begin to play a role in determining the threshold. Throughout the visible region of the spectrum the threshold is still an increasing function of frequency, indicating that avalanche ionization is the dominant factor in determining the breakdown threshold. This was confirmed by a detailed study of the damage morphology with a high resolution microscope just above the threshold. The influence of self focusing is discussed, and evidence for beam distortion below the power threshold for complete self focusing is presented, confirming the theory of Marburger.

Smith, W. L.; Bechtel, J. H.; Bloembergen, N.

1976-01-01

391

Recent Progress in Electrical Insulation Techniques for HTS Power Apparatus  

NASA Astrophysics Data System (ADS)

This paper describes the electrical insulation techniques at cryogenic temperatures, i.e. Cryodielectrics, for HTS power apparatus, e.g. HTS power transmission cables, transformers, fault current limiters and SMES. Breakdown and partial discharge characteristics are discussed for different electrical insulation configurations of LN2, sub-cooled LN2, solid, vacuum and their composite insulation systems. Dynamic and static insulation performances with and without taking account of quench in HTS materials are also introduced.

Hayakawa, Naoki; Kojima, Hiroki; Hanai, Masahiro; Okubo, Hitoshi

392

Runaway electron mechanism of air breakdown and preconditioning during a thunderstorm  

Microsoft Academic Search

The possibility is considered of an avalanche-type increase of the number of runaway electrons leading to a new type of electric breakdown of gases. This type of breakdown could take place in the atmosphere during a thunderstorm stimulated by cosmic ray secondaries.

A. V. Gurevich; G. M. Milikh; R. Roussel-Dupre

1992-01-01

393

An Examination of the Statistics of Breakdown in a Pressurized, Flowing, Synthetic Oil Dielectric  

Microsoft Academic Search

An investigation of the statistical properties of dielectric breakdown in the synthetic oil dielectric poly-alpha olefin as a function of both oil pressure and inter-electrode gap separation has generated several important findings. Our results confirm previous investigators' findings relating a nonlinear relationship between the mean breakdown electric field strength and the operating pressure. We demonstrate a similar effect relating the

P. Norgard; R. Curry

2008-01-01

394

Electrical characteristics and interface structure of magnetic tunnel junctions with hafnium oxyfluoride barrier  

SciTech Connect

We have studied the effects of fluorine inclusion on the electrical transport characteristics and interface structure of the hafnium oxide barrier in a magnetic tunnel junction. The tunneling magnetoresistance (TMR) and resistance-area (RA) as a function of oxidation time show that the TMR ratio of the hafnium oxyfluoride barrier is higher (8.3%) than that of the hafnium oxide barrier (5.7%) at their optimum conditions, and the oxyfluoride barrier junctions maintain a high TMR ratio even when the RA product increases by three orders of magnitude. X-ray photoelectron spectroscopy analysis shows that the fluorine atoms in the oxyfluoride barrier play an important role in the formation of a barrier with uniform composition. We believe that the initial fluoride layer is causing the subsequent oxygen diffusion to slow down, resulting in the formation of a defect-free hafnium oxide layer. These results are consistent with what we have found for aluminum oxyfluoride barriers.

Yu, Y.Y.; Kim, D.S.; Char, K. [Center for Strongly Correlated Materials Research and School of Physics, Seoul National University, Seoul 151-742 (Korea, Republic of)

2004-12-01

395

Simplified fabrication of back surface electric field silicon cells and novel characteristics of such cells.  

NASA Technical Reports Server (NTRS)

An investigation of the characteristics and behavior of 10 ohm-cm silicon cells having abnormally high open-circuit voltages was made. The cells studied were made by a new, highly simplified, contact fabrication process which creates both a contact and a thin electric field region at the cell back surface without the need for phosphorus layer removal. These cells had open-circuit voltages of about 0.58 V and their performance as a function of thickness, temperature, and 1 MeV electron irradiation is detailed. The study showed that 10 ohm-cm back-surface-field cells can have the high initial efficiencies and desirable temperature behavior of low resistivity cells. Thin back-surface-field cells were made and showed, in addition, much greater radiation damage resistance. A mechanism is proposed to explain the results.

Mandelkorn, J.; Lamneck, J. H., Jr.

1972-01-01

396

Simplified fabrication of back surface electric field silicon cells and novel characteristics of such cells  

NASA Technical Reports Server (NTRS)

An investigation of the characteristics and behavior of 10 ohm-cm silicon cells having abnormally high open-circuit voltages was made. The cells studied were made by a new, highly simplified, contact fabrication process which creates both a contact and a thin electric field region at the cell back surface without the need for phosphorus layer removal. These cells had open-circuit voltages of about 0.58 V and their performance as a function of thickness, temperature, and 1 MeV electron irradiation is detailed. The study showed that 10 ohm-cm back-surface-field cells can have the high initial efficiencies and desirable temperature behavior of low resistivity cells. Thin back-surface-field cells were made and showed, in addition, much greater radiation damage resistance. A mechanism is proposed to explain the results.

Mandelkorn, J.; Lamneck, J. H., Jr.

1972-01-01

397

Hybrid nanocomposite based on cellulose and tin oxide: growth, structure, tensile and electrical characteristics  

NASA Astrophysics Data System (ADS)

A highly flexible nanocomposite was developed by coating a regenerated cellulose film with a thin layer of tin oxide (SnO2) by liquid-phase deposition. Tin oxide was crystallized in solution and formed nanocrystal coatings on regenerated cellulose. The nanocrystalline layers did not exfoliate from cellulose. Transmission electron microscopy and energy dispersive x-ray spectroscopy suggest that SnO2 was not only deposited over the cellulose surface, but also nucleated and grew inside the cellulose film. Current-voltage characteristics of the nanocomposite revealed that its electrical resistivity decreases with deposition time, with the lowest value obtained for 24 h of deposition. The cellulose-SnO2 hybrid nanocomposite can be used for biodegradable and disposable chemical, humidity and biosensors.

Mahadeva, Suresha K.; Kim, Jaehwan

2011-10-01

398

Electrical Conductivity Characteristic of TiO2 Nanowires From Hydrothermal Method  

NASA Astrophysics Data System (ADS)

One dimensional nanostructures of titanium dioxide (TiO2) were synthesized via hydrothermal method by mixing TiO2 as precursor in aqueous solution of NaOH as solvent. Then, heat and washing treatment was applied. Thus obtained wires had diameter ~15nm. TiO2 nanowires will be used as a network in solar cell such dye-sensitized solar cell in order to improve the performance of electron movement in the device. To improve the performance of electron movement, the characteristics of TiO2 nanowires have been analyses using field emission scanning electron microscopy (FESEM) analysis, x-ray diffractometer (XRD) analysis and brunauer emmett teller (BET) analysis. Finally, electrical conductivity of TiO2 nanowires was determined by measuring the resistance of the TiO2 nanowires paste on microscope glass.

Azlishah Othman, Mohd; Faridah Amat, Noor; Hisham Ahmad, Badrul; Rajan, Jose

2014-04-01

399

Some characteristics of polymers in composite materials and as electrical conductors  

NASA Technical Reports Server (NTRS)

The characteristics of carbon fibers (CF) made from polyacrylonitrile (PAN) materials are discussed, together with research on conducting polymers. CF materials have better mechanical properties, chemical inertness, and higher stiffness than metallic materials but are subject to environmental instability, flammability, and delamination fatigue. Polymerization procedures for the monopolymer PAN are described, noting the use of SEM and X-ray diffraction techniques for studying the fiber structure. High modulus and strength of CF are caused by covalent sp(2) bonds in hexagonal carbon rings, which are stronger than the same links in diamonds. Details of the molecular chain structures and macroformations, stress-strain as a function of temperature, and thermosetting and glass transition temperatures of polymers are provided. Computational quantum chemistry techniques are being applied to studying electrical conductance in polymers, mainly to discover ways to stabilize the materials. Doped CH(x) has exhibited photovoltaic properties and other polymers have become superconductors at cryogenic temperatures.

Hansen, C. F.

1982-01-01

400

Optical breakdown threshold investigation of 1064 nm laser induced air plasmas  

SciTech Connect

We present the theoretical and experimental measurements and analysis of the optical breakdown threshold for dry air by 1064 nm infrared laser radiation and the significance of the multiphoton and collisional cascade ionization process on the breakdown threshold measurements over pressures range from 10 to 2000 Torr. Theoretical estimates of the breakdown threshold laser intensities and electric fields are obtained using two distinct theories namely multiphoton and collisional cascade ionization theories. The theoretical estimates are validated by experimental measurements and analysis of laser induced breakdown processes in dry air at a wavelength of 1064 nm by focusing 450 mJ max, 6 ns, 75 MW max high-power 1064 nm IR laser radiation onto a 20 {mu}m radius spot size that produces laser intensities up to 3 - 6 TW/cm{sup 2}, sufficient for air ionization over the pressures of interest ranging from 10 to 2000 Torr. Analysis of the measured breakdown threshold laser intensities and electric fields are carried out in relation with classical and quantum theoretical ionization processes, operating pressures. Comparative analysis of the laser air breakdown results at 1064 nm with corresponding results of a shorter laser wavelength (193 nm) [M. Thiyagarajan and J. E. Scharer, IEEE Trans. Plasma Sci. 36, 2512 (2008)] and a longer microwave wavelength (10{sup 8} nm) [A. D. MacDonald, Microwave Breakdown in Gases (Wiley, New York, 1966)]. A universal scaling analysis of the breakdown threshold measurements provided a direct comparison of breakdown threshold values over a wide range of frequencies ranging from microwave to ultraviolet frequencies. Comparison of 1064 nm laser induced effective field intensities for air breakdown measurements with data calculated based on the collisional cascade and multiphoton breakdown theories is used successfully to determine the scaled collisional microwave portion. The measured breakdown threshold of 1064 nm laser intensities are then scaled to classical microwave breakdown theory after correcting for the multiphoton ionization process for different pressures and good agreement, regarding both pressure dependence and breakdown threshold electric fields, is obtained. The effect of the presence of submicron particles on the 1064 nm breakdown threshold was also investigated. The measurements show that higher breakdown field is required, especially at lower pressures, and in close agreement with classical microwave breakdown theory and measurements in air.

Thiyagarajan, Magesh; Thompson, Shane [Plasma Engineering Research Lab (PERL), College of Science and Engineering, Texas A and M University-Corpus Christi, Texas 78412 (United States)

2012-04-01

401

Study of bulk and elementary screw dislocations assisted reverse breakdown in low-voltage (<250 V) 4H-SiC p{sup +}n junction diodes. Part 1: DC properties  

SciTech Connect

Given the high-density ({approximately}10{sup 4} cm{sup {minus}2}) of elementary screw dislocations (Burgers vector = 1c with no hollow core) in commercial SiC wafers and epilayers, all large current (>1 A) SiC power devices will likely contain elementary screw dislocations for the foreseeable future. It is therefore important to ascertain the electrical impact of these defects, particularly in high-field vertical power device topologies where SiC is expected to enable large performance improvements in solid-state high-power systems. This paper compares the dc-measured reverse-breakdown characteristics of low-voltage (<250 V) small-area (<5 {times} 10{sup {minus}4} cm{sup 2}) 4H-SiC p{sup +}n diodes with and without elementary screw dislocations. Diodes containing elementary screw dislocations exhibited higher pre-breakdown reverse leakage currents, softer reverse breakdown current-voltage (I-V) knees, and highly localized microplasmic breakdown current filaments compared to screw dislocation-free devices. The observed localized 4H-SiC breakdown parallels microplasmic breakdown observed in silicon and other semiconductors, in which space-charge effects limit current conduction through the local microplasma as reverse bias is increased.

Neudeck, P.G. [NASA Lewis Research Center, Cleveland, OH (United States)] [NASA Lewis Research Center, Cleveland, OH (United States); Huang, W.; Dudley, M. [State Univ. of New York, Stony Brook, NY (United States). Dept. of Materials Science and Engineering] [State Univ. of New York, Stony Brook, NY (United States). Dept. of Materials Science and Engineering

1999-03-01

402

Electrical characteristics of metal-dielectric-semiconductor systems produced on epitaxial silicon structures with various dielectrics  

NASA Astrophysics Data System (ADS)

An experimental study was made of MDS systems with silicon as semiconductor, for the purpose of determining the dependence of their electrical characteristics on the dielectric material. Epitaxial 10 micron thick films of n-Si with electrical resistivity RHO approx 0.8-1 ohm cm were grown on p-Si substrates with resistivity RHO = 10 oh.cm, and the field electrode with a surface area of 0.44 sq mm. In one experiment, three dielectric materials were used: SiO2 produced by thermal oxidation, SiO2 produced by anodic oxidation, and Dy2O3. Both material and deposition process determined the surface condition and the thickness of the space charge reagion as well as the carrier concentration in it. Switching from high-resistance state to low-resistance state was stable and repeatable in each case. While the total low resistance of the MDS device was within 10 to the 2nd power to 10 to the 3rd power ohm and almost independent of the dielectric material, the leakage current in the high-resistance state was highest through thermal SiO2 (10 to the 4th power to 10 to the 5th power ohm, switching voltage 7 V) and lowest through anodic SiO2 (10 to the 7th power ohm, switching voltage 18-23 V) with dy2O3 in the intermediate range. Current-voltage characteristics were measured at frequencies from 20 Hz to 20 kHz with direct current and at the test signal frequency of 0.465 MHz.

Fomicheva, O. F.; Otavina, L. A.; Sverdlova, A. M.; Kapshtal, G. G.

1984-07-01

403

Geometric dependence of radio-frequency breakdown in normal conducting accelerating structures  

SciTech Connect

We present the experimental results of a systematic study of rf breakdown phenomenon in high vacuum accelerator structures. In this study, the surface processing, geometry, and materials of the structures have been varied, one parameter at a time. The breakdown rate or alternatively, the probability of breakdown/pulse/meter has been recorded for different operating parameters. These statistical data reveal a strong dependence of breakdown probability on surface magnetic field, or alternatively on surface pulsed heating. This is in contrast to the classical view of electric field dependence. We will present our experimental methodology and results showing this remarkable correlation.

Dolgashev, Valery; Tantawi, Sami [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Higashi, Yasuo [High Energy Accelerator Research Organization, KEK, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Spataro, Bruno [INFN-LNF, 00044 Frascati (Italy)

2010-10-25

404

Electrical discharge machining of carbon nanomaterials in air: machining characteristics and the advanced field emission applications  

NASA Astrophysics Data System (ADS)

A reliable and precise machining process, electrical discharge machining (EDM), was investigated in depth as a novel method for the engineering of carbon nanomaterials. The machining characteristics of EDM applied to carbon nanomaterials 'in air' were systematically examined using scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), energy-dispersive x-ray spectroscopy (EDS), x-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The EDM process turned out to 'melt' carbon nanomaterials with the thermal energy generated by electrical discharge, which makes both the materially and geometrically unrestricted machining of nanomaterials possible. Since the EDM process conducted in air requires neither direct contact nor chemical agents, it protects the carbon nanomaterial workpieces against physical damage and unnecessary contamination. From this EDM method, several advanced field emission applications including 'top-down' patterning and the creative lateral comb-type triode device were derived, while our previously reported study on emission uniformity enhancement by the EDM method was also referenced. The EDM method has great potential as a clean, effective and practical way to utilize carbon nanomaterials for various uses.

Ok, Jong Girl; Kim, Bo Hyun; Chung, Do Kwan; Sung, Woo Yong; Lee, Seung Min; Lee, Se Won; Kim, Wal Jun; Park, Jin Woo; Chu, Chong Nam; Kim, Yong Hyup

2008-02-01

405

Analysis on electrical characteristics of high-voltage GaN-based light-emitting diodes  

NASA Astrophysics Data System (ADS)

In order to investigate their electrical characteristics, high-voltage light-emitting-diodes (HV-LEDs) each containing four cells in series are fabricated. The electrical parameters including varying voltage and parasitic effect are studied. It is shown that the ideality factors (IFs) of the HV-LEDs with different numbers of cells are 1.6, 3.4, 4.7, and 6.4. IF increases linearly with the number of cells increasing. Moreover, the performance of the HV-LED with failure cells is examined. The analysis indicates that the failure cell has a parallel resistance which induces the leakage of the failure cell. The series resistance of the failure cell is 76.8 ?, while that of the normal cell is 21.3 ?. The scanning electron microscope (SEM) image indicates that different metal layers do not contact well. It is hard to deposit the metal layers in the deep isolation trenches. The fabrication process of HV-LEDs needs to be optimized.

Guo, Wei-Ling; Yan, Wei-Wei; Zhu, Yan-Xu; Liu, Jian-Peng; Ding, Yan; Cui, De-Sheng; Wu, Guo-Qing

2012-12-01

406

Micropatterned Polypyrrole: A Combination of Electrical and Topographical Characteristics for the Stimulation of Cells.  

PubMed

Electrically conducting polymers such as polypyrrole (PPy) are important biomaterials in neural engineering applications, including neural probes, nerve conduits, and scaffolds for tissue and nerve regeneration. Surface modification of these polymers can introduce other valuable characteristics for neural interfacing in addition to electrical conductivity, such as topographical features and chemical bioactivity. Here, the patterning of PPy to create topographical cues for cells is reported. In particular, 1 and 2 µm wide PPy microchannels are fabricated using electron-beam (e-beam) lithography and electropolymerization. A systematic analysis of parameters controlling PPy micropatterning is performed, and finds that microchannel depth, roughness, and morphology are highly dependent on the e-beam writing current, polymerization current, PPy/dopant concentrations, and the polymerization time. Embryonic hippocampal neurons cultured on patterned PPy polarize (i.e., defined an axon) faster on this modified material, with a twofold increase in the number of cells with axons compared to cells cultured on unmodified PPy. These topographical features also have an effect on axon orientation but do not have a significant effect on overall axon length. This is the first investigation that studies controlled PPy patterning with small dimensions (i.e., less than 5 µm) for biological applications, which demonstrates the relevance of expanding microelectronic materials and techniques to the biomedical field. PMID:19655035

Gomez, Natalia; Lee, Jae Y; Nickels, Jon D; Schmidt, Christine E

2007-07-01

407

Numerical simulation of vortex breakdown  

NASA Technical Reports Server (NTRS)

The breakdown of an isolated axisymmetric vortex embedded in an unbounded uniform flow is examined by numerical integration of the complete Navier-Stokes equations for unsteady axisymmetric flow. Results show that if the vortex strength is small, the solution approaches a steady flow and the vortex is stable. If the strength is large enough, the solution remains unsteady and a recirculating zone will appear near the axis, its form and internal structure resembling those of the axisymmetric breakdown bubbles with multi-cells observed by Faler and Leibovich (1978). For apppropriate combinations of flow parameters, the flow reveals quasi-periodicity. Parallel calculations with the quasi-cylindrical approximation indicate that so far as predicting of breakdown is concerned, its results coincide quite well with the results mentioned above. Both show that the vortex breakdown has little concern with the Reynolds number or with the critical classification of the upstream flow, at least for the lower range of Reynolds numbers.

Shi, X.

1985-01-01

408

Water treeing and breakdown strength reduction of XLPE insulation  

Microsoft Academic Search

An effort was made to determine factors influencing initiation and growth of vented water trees and to study the reduction of breakdown strength caused by water treeing. Water treeing experiments were performed on both cable samples and Rogowski-type test objects. The influence of aging time and electric field stress was elucidated. In order to test the hypothesis that water treeing

E. Ildstad; J. Sletbak; H. Faremo

1989-01-01

409

Studies of dielectric breakdown under pulsed power conditions  

Microsoft Academic Search

Summary form only given. In an effort to develop transmission lines with higher energy storage capabilities for compact pulsed power applications we have been developing and studying ceramic dielectrics and their electrical breakdown strength (BDS). Results of research to-date show that dense titania ceramics with nanocrystalline grain size (?200 nm) exhibit significantly higher BDS as compared to ceramics made using

P. Castro; M. Roybal; J. Buchenauer; J. Gaudet; E. Schamiloglu

2004-01-01

410

Studies of Dielectric Breakdown Under Pulsed Power Conditions  

Microsoft Academic Search

In an effort to develop transmission lines with higher energy storage capabilities for compact pulsed power applications, ceramic dielectrics and their electrical breakdown strength (BDS) are being developed and studied. Results of research to-date show that the dense titania ceramics with nanocrystalline grain size (-200 nm) exhibit significantly higher BDS as compared to ceramics made using coarse grain materials when

P. Castro; C. J. Buchenauer; J. Gaudet; E. Schamiloglu

2005-01-01

411

High voltage breakdown strength of rapid prototype materials  

Microsoft Academic Search

We report measurements on the breakdown strength of plastics used in stereo lithography for rapid prototyping. Three epoxy-based photopolymer resins commonly used for stereo lithography were the focus of this work. Test samples were manufactured with an electrically smooth geometry to minimize field enhancements. The thickness of the stressed region in the samples was nominally 1 or 2 mm. Samples

F. E. Peterkine; J. L. Stevens; J. F. Sharrow; R. K. Pitman

2003-01-01

412

Direct current breakdown in gases for complex geometries from high vacuum to atmospheric pressure  

NASA Astrophysics Data System (ADS)

The demand for improved performances of power transmission devices requires ever smaller dimensions and higher working voltages which lead to increased risk of breakdown, for example, in satellite slip rings. Previous works are mostly limited to breakdown in simple geometries such as parallel plates or pin to plate. Here we discuss the effect of more complex geometries for dc breakdown in gases over a large pressure range (2 × 10-5 to 103 mbar). Experimental measurements of dc gas discharge breakdown in a ring assembly geometry are compared with a numerical simulation model for gas breakdown using a fluid model. Starting with parallel plates (1 and 100 mm gap width representing approximately the shortest and longest electric field path lengths in the ring assembly geometry) and extending to double gap and multi-gap geometries, an understanding of the overall shape of the breakdown voltage versus pressure curve is established. The high (low) pressure thresholds of gas discharge are determined by the shortest (longest) electric field path length in a complex geometry. Moreover, the availability of multiple path lengths leads to a breakdown voltage minimum over a wide range of intermediate pressure because breakdown can occur in the most favourable gap. Finally, the numerical simulation in the ring assembly shows the importance of parameters such as the secondary electron emission coefficient which play a major role in determining the breakdown voltage value.

Schnyder, R.; Howling, A. A.; Bommottet, D.; Hollenstein, Ch

2013-07-01

413

Breakdown mechanism of an atmospheric-pressure radio-frequency capacitive argon discharge in parallel-plate bare metal electrodes  

NASA Astrophysics Data System (ADS)

The breakdown behavior of an atmospheric-pressure radio-frequency capacitively coupled argon plasma discharge at 13.56 MHz is investigated in order to produce a stable and homogeneous atmospheric-pressure argon glow discharge. It is found that the electrode separation distance plays a pivotal role in exciting argon discharge whether in mobility-controlled electric breakdown or in diffusion-controlled breakdown and the discharge mode (arc discharge, ?-mode glow discharge, or ?-mode glow discharge) immediately following breakdown is closely related to the breakdown mechanism.

Li, Shou-Zhe; Wu, Qi; Wang, Dezhen; Uhm, Han S.

2011-01-01

414

Recurrent neuro-fuzzy predictors for multi-step prediction of v-i characteristics of electric arc furnaces  

Microsoft Academic Search

Presents an application of recurrent neuro-fuzzy systems to predict electric arc furnaces voltage and current. The primary objective is to investigate capability of adaptive fuzzy systems to predict the v-i characteristics of nonlinear, multivariable, complex systems such as electric furnaces. The novelties of this work are proposing a combination of recurrent neuro-fuzzy networks deemed suitable for prediction and using a

A. R. Sadeghian; J. D. Lavers

2000-01-01

415

Study on Factors in Increase of Breakdown Strength of Gas Mixed with Liquid Mist.  

National Technical Information Service (NTIS)

It has been suggested that the breakdown strength of gaseous dielectrics may gently increase by mixing liquid mist such as carbon-halide mist. In the previous paper, the authors investigated the breakdown characteristics of gaseous dielectrics of N(sub 2)...

M. Yashima H. Fujinami T. Takuma

1989-01-01

416

Organizational and Individual Factors Associated with Breakdown of Residential Placements for People with Intellectual Disabilities  

ERIC Educational Resources Information Center

Background: People with intellectual disabilities (IDs) whose behaviour challenges services are at increased risk of placement breakdown. Most previous research has tended to focus on the role of individual characteristics in predicting breakdown. A small number of studies have suggested that service variables may impact on intervention…

Broadhurst, S.; Mansell, J.

2007-01-01

417

Accelerated testing for time dependent dielectric breakdown (TDDB) evaluation of embedded DRAM capacitors using tantalum pentoxide  

Microsoft Academic Search

Mechanisms of breakdown in Ta2O5 are evaluated by studying the leakage and TDDB characteristics, and a model close to those widely accepted for SiO2 is suggested. Various statistical modeling approaches are evaluated and used to verify this breakdown model. Accelerated testing techniques are also outlined that can dramatically improve parameter estimates while slashing reliability test times.

Anand Inani; Victor Koldyaev; Spencer Graves

2007-01-01

418

Ion Solid Interaction And Surface Modification At RF Breakdown In High-Gradient Linacs  

SciTech Connect

Ion solid interactions have been shown to be an important new mechanism of unipolar arc formation in high-gradient rf linear accelerators through surface self-sputtering by plasma ions, in addition to an intense surface field evaporation. We believe a non-Debye plasma is formed in close vicinity to the surface and strongly affects surface atomic migration via intense bombardment by ions, strong electric field, and high surface temperature. Scanning electron microscope studies of copper surface of an rf cavity were conducted that show craters, arc pits, and both irregular and regular ripple structures with a characteristic length of 2 microns on the surface. Strong field enhancements are characteristic of the edges, corners, and crack systems at surfaces subjected to rf breakdown.

Insepov, Zeke; Norem, Jim [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Veitzer, Seth [Tech-X Corp., 5621 Arapahoe Ave., Suite A, Boulder CO 80303 (United States)

2011-06-01

419

Electricity  

NSDL National Science Digital Library

5th Grade Electricity Try this Using Electricity Activity. Don't forget to follow the directions! Use this to learn more about electricity: Blobz Guide to Electricity Follow the directions closely! Learn more about Electricity with Electricity Tech-Topics. ...

Lerdahl, Miss

2010-02-23

420

Investigation of the dc vacuum breakdown mechanism  

NASA Astrophysics Data System (ADS)

Breakdowns occurring in rf accelerating structures will limit the ultimate performance of future linear colliders such as the Compact Linear Collider (CLIC). Because of the similarity of many aspects of dc and rf breakdown, a dc breakdown study is underway at CERN to better understand the vacuum breakdown mechanism in a simple setup. Measurements of the field enhancement factor ? show that the local breakdown field is constant and depends only on the electrode material. With copper electrodes, the local breakdown field is around 10.8GV/m, independent of the gap distance. The ? value characterizes the electrode surface state, and the next macroscopic breakdown field can be well predicted. In breakdown rate experiments, where a constant field is applied to the electrodes, clusters of consecutive breakdowns alternate with quiet periods. The occurrence and lengths of these clusters and quiet periods depend on the evolution of ?. The application of a high field can even modify the electrode surface in the absence of breakdown. Measurements of time delays to breakdown show two distinct populations, immediate and delayed breakdowns, indicating that two different mechanisms could exist. The ratio of these two populations depends on the conditioning state of the electrodes and on material. Gas release during breakdown is dominated by H2 and CO. This degassing is mainly due to electron-stimulated desorption. During the quiet periods without breakdown, gases are also released but the quantities are much smaller. All the measurements presented here emphasize the crucial role of field emission in the breakdown triggering.

Descoeudres, A.; Levinsen, Y.; Calatroni, S.; Taborelli, M.; Wuensch, W.

2009-09-01

421

The electrical properties and d.c. degradation characteristics of silver doped ZnO varistors  

Microsoft Academic Search

ZnO-Bi2O3-based ceramic varistors containing up to 2500 p.p.m. Ag2O were prepared by the mixed oxide route. The products were characterized in terms of current-voltage (I–V) behaviour, capacitance-voltage (C-V) behaviour and d.c. degradation behaviour. Additions of silver did not significantly affect ZnO grain growth or sintered density, but decreased the non-linearity exponent, a, and increased the breakdown voltage. Silver-doped specimens exhibited

J. Fan; R. Freer

1993-01-01

422

Effects of filtration on the impulse breakdown strength of high-purity water  

Microsoft Academic Search

High-purity water is the dielectric of choice for most pulsed-power machines. Increasing the electrical breakdown strength of high-purity water is one of the principle goals for pulsed power, because the energy density stored in the water increases as the square of the electric field. This paper concentrates on the impulse breakdown strength for long-stress times (i.e., greater than 65 microseconds).

Victor H. Gehman; Ronald J. Gripshover; Thomas L. Berger; Samuel P. Bowen; Royce K. P. Zia

1995-01-01

423

Electrical characterization of ZnO-based homojunctions  

NASA Astrophysics Data System (ADS)

Electrical characteristics have been studied for ZnO p-n and p-i-n homojunctions, with optimization of device structures for improved performance. Capacitance-voltage measurements confirm the formation of abrupt junctions. The current-voltage characteristics exhibit their inherent electrical rectification behavior. The p-ZnO:(N,Al)/n-ZnO:Al homojunctions fabricated on sapphire substrates combining with the intrinsic ZnO buffer layer have acceptable p-n diode characteristics, with the forward turn-on voltage of 1.4 V and the reverse breakdown voltage of 5.3 V. By introduction of an intrinsic (Zn,Cd)O layer, the resultant p-ZnO:(N,Al)/i-(Zn,Cd)O/n-ZnO:Al homojunction exhibits a high reverse breakdown voltage of ~18 V.

Lu, J. G.; Ye, Z. Z.; Yuan, G. D.; Zeng, Y. J.; Zhuge, F.; Zhu, L. P.; Zhao, B. H.; Zhang, S. B.

2006-07-01

424

High-voltage atmospheric breakdown across intervening rutile dielectrics.  

SciTech Connect

This report documents work conducted in FY13 on electrical discharge experiments performed to develop predictive computational models of the fundamental processes of surface breakdown in the vicinity of high-permittivity material interfaces. Further, experiments were conducted to determine if free carrier electrons could be excited into the conduction band thus lowering the effective breakdown voltage when UV photons (4.66 eV) from a high energy pulsed laser were incident on the rutile sample. This report documents the numerical approach, the experimental setup, and summarizes the data and simulations. Lastly, it describes the path forward and challenges that must be overcome in order to improve future experiments for characterizing the breakdown behavior for rutile.

Williamson, Kenneth Martin; Simpson, Sean; Coats, Rebecca Sue; Jorgenson, Roy Eberhardt; Hjalmarson, Harold Paul; Pasik, Michael Francis

2013-09-01

425

Optoelectronic switching in diamond and optical surface breakdown  

SciTech Connect

The optoelectronic switching in two natural diamond samples of type 2-A is studied at voltages up to 1000 V and the energy density of control 60-ns, 308-nm laser pulses up to 0.6 J cm{sup -2}. It is shown that the design of a diamond switch affects the switching efficiency. When the energy density exceeds 0.2 J cm{sup -2} and the interelectrode surface is completely illuminated, the surface breakdown is initiated by UV radiation, which shunts the current flow through the diamond crystal. When the illumination of the interelectrode surface is excluded, the surface breakdown does not occur. The threshold radiation densities sufficient for initiating the surface breakdown are determined for electric field strengths up to 10 kV cm{sup -1}. (laser applications and other topics in quantum electronics)

Lipatov, E I; Tarasenko, V F [Institute of High Current Electronics, Siberian Branch, Russian Academy of Sciences, Tomsk (Russian Federation)

2008-03-31

426

Breakdown voltage reduction by field emission in multi-walled carbon nanotubes based ionization gas sensor  

NASA Astrophysics Data System (ADS)

Ionization gas sensors using vertically aligned multi-wall carbon nanotubes (MWCNT) are demonstrated. The sharp tips of the nanotubes generate large non-uniform electric fields at relatively low applied voltage. The enhancement of the electric field results in field emission of electrons that dominates the breakdown mechanism in gas sensor with gap spacing below 14 ?m. More than 90% reduction in breakdown voltage is observed for sensors with MWCNT and 7 ?m gap spacing. Transition of breakdown mechanism, dominated by avalanche electrons to field emission electrons, as decreasing gap spacing is also observed and discussed.

Saheed, M. Shuaib M.; Muti Mohamed, Norani; Arif Burhanudin, Zainal

2014-03-01

427

Direct measurement of the characteristic three-body electron attachment time in the atmospheric air in direct current electric field  

NASA Astrophysics Data System (ADS)

We report the results of theoretical and experimental study of the characteristic time for three-body attachment of electrons produced by 100 fs UV laser pulse in the atmosphere air in the external DC electric field ranged from 0.2 to 10 kV/cm.

Shutov, A. V.; Smetanin, I. V.; Ionin, A. A.; Levchenko, A. O.; Seleznev, L. V.; Sinitsyn, D. V.; Ustinovskii, N. N.; Zvorykin, V. D.

2013-07-01

428

Direct measurement of the characteristic three-body electron attachment time in the atmospheric air in direct current electric field  

SciTech Connect

We report the results of theoretical and experimental study of the characteristic time for three-body attachment of electrons produced by 100 fs UV laser pulse in the atmosphere air in the external DC electric field ranged from 0.2 to 10 kV/cm.

Shutov, A. V.; Smetanin, I. V.; Ionin, A. A.; Levchenko, A. O.; Seleznev, L. V.; Sinitsyn, D. V.; Ustinovskii, N. N.; Zvorykin, V. D. [P. N. Lebedev Physical Institute, Leninskii Prospect 53, Moscow 119991 (Russian Federation)

2013-07-15

429

Estimation of aquifer hydraulic characteristics from electrical sounding data: the case of middle Imo River basin aquifers, south- eastern Nigeria  

Microsoft Academic Search

We have used the concept of Da - Zarrouk parameters (transverse unit resistance (R) and longitudinal conductance (C)) in porous media to determine aquifer hydraulic characteristics within the middle Imo river basin. The lithostratigraphic units within the study area include: Imo formation, Bende - Ameki formation, Ogwashi Asaba formation and Benin formation. The direct current electrical resistivity method was utilized

A. C. Ekwe; N. N. Onu; K. M. Onuoha

430

Metastable Electrical Characteristics of Polycrystalline Thin-Film Photovoltaic Modules upon Exposure and Stabilization: Preprint  

SciTech Connect

The significant features of a series of stabilization experiments conducted at the National Renewable Energy Laboratory (NREL) between May 2009 and the present are reported. These experiments evaluated a procedure to stabilize the measured performance of thin-film polycrystalline cadmium telluride (CdTe) and copper indium gallium diselenide (CIGS) thin-film photovoltaic (PV) modules. The current-voltage (I-V) characteristics of CdTe and CIGS thin-film PV devices and modules exhibit transitory changes in electrical performance after thermal exposure in the dark and/or bias and light exposures. We present the results of our case studies of module performance versus exposure: light-soaked at 65 degrees C; exposed in the dark under forward bias at 65 degrees C; and, finally, longer-term outdoor exposure. We find that stabilization can be achieved to varying degrees using either light-soaking or dark bias methods and that the existing IEC 61646 light-soaking interval may be appropriate for CdTe and CIGS modules with one caveat: it is likely that at least three exposure intervals are required for stabilization.

Deline, C. A.; del Cueto, J. A.; Albin, D. S.; Rummel, S. R.

2011-09-01

431

NOTE: Effects of powder additives suspended in dielectric on crater characteristics for micro electrical discharge machining  

NASA Astrophysics Data System (ADS)

The effects of using powder additives suspended in dielectric on crater characteristics for micro electrical discharge machining (PSD micro-EDM) are investigated through the conduct of single RC discharge experiments at low discharge energies of 2.5 µJ, 5 µJ and 25 µJ. Through the introduction of additive particles into the dielectric, results of the single discharge experiments show the formation of craters with smaller diameters and depths, and having more consistent circular shapes than those produced in dielectric without additive. These craters also possess a noticeable morphological difference compared to those generated in dielectric without additive. In addition, discharge current measurements show a smaller amount of charges flowing between the tool electrode and workpiece, and at a slower flow rate when additives are present in the dielectric. Furthermore, based on the experimental results and findings from studies done in nanofluids, a hypothesis is made on the effects of powder suspended dielectric on the crater formation mechanism. The increased viscosity and enhanced thermal conductivity of a powder suspended dielectric lower the plasma heat flux into the electrode and raise the rate of heat dissipation away from the molten cavity. As a result, a smaller-sized crater having a larger amount of resolidified material within the crater cavity is formed.

Yeo, S. H.; Tan, P. C.; Kurnia, W.

2007-11-01

432

Electrical properties of epoxy resin based nano-composites  

SciTech Connect

We investigate the electrical properties of composite materials prepared as nano and sub-micro scale metal-oxide particles embedded in a commercial resin. The filler particles are barium titanate and calcium copper titanate. The physical and structural characteristics of constituents and the fabricated composites are reported. The electrical characterization of the composite samples are performed with the time- and frequency-domain dielectric spectroscopy techniques. The electrical breakdown strength of samples with nano and sub-micron size particles have better electrical insulation properties than the unfilled resin.

Tuncer, Enis [ORNL; Sauers, Isidor [ORNL; James, David Randy [ORNL; Ellis, Alvin R [ORNL; Paranthaman, Mariappan Parans [ORNL; Aytug, Tolga [ORNL; Sathyamurthy, Srivatsan [ORNL; More, Karren Leslie [ORNL; Li, Jing [ORNL; Goyal, Amit [ORNL

2007-01-01

433

Electricity  

NSDL National Science Digital Library

William J. Beaty, an Electrical Engineer at the University of Washington, has posted this website about electricity. He offers a simple answer to the question, What Is "Electricity?," identifies twenty misconceptions he has found to be barriers to understanding electricity, and then proceeds to explain various aspects of electricity. Beaty's debunking articles address common misconceptions about circuitry, doorknob sparks, voltage, and more.

Beaty, William J.

434

Dielectric breakdown of polycrystalline alumina: A weakest-link failure analysis  

NASA Astrophysics Data System (ADS)

The effects of varying electrode geometry (ball and ring) and size (radius), dielectric media (castor oil and DialaRTM oil), specimen thickness, and concentration of defects on the dielectric breakdown strength of commercial-grade alumina and high-purity fine-grained (HPFG) alumina were investigated. The breakdown strength was expressed in terms of the maximum electric field in the ceramic at the breakdown voltage calculated by finite element analysis (FEA). The breakdown strength decreased systematically with increasing electrode radius and specimen thickness. The breakdown strength increased with decreasing concentration of defects. The breakdown strength was higher in the Diala RTM oil (dielectric constant, epsilonr = 2.3 +/- 0.12) as compared to the castor oil (epsilonr = 4.59 +/- 0.06). The breakdown strength was higher for the HPFG alumina as compared to the commercial- grade alumina. These effects of the electrode geometry, specimen thickness, concentration of defects, and of the dielectric media were analyzed with a weakest-link failure model employing the Laplace and Weibull distributions for a population of defects in the material. The measured size or scaling effects of the electrodes, specimen thickness, concentration of defects, and of the liquid media on breakdown strength were in better agreement with the Laplace distribution for the population. The measured concentration of surface defects was in good agreement with the concentration of surface defects estimated from the surface area scaling of the breakdown field with the Laplace distribution.

Block, Benjamin

435

Use characteristics and mode choice behavior of electric bike users in China  

Microsoft Academic Search

In 2005, 10 million electric bikes were produced in China. Strong domestic sales are projected for coming years, raising concerns about the sustainability and potential regulation of this fairly new mode. Policy makers are wrestling with developing policy on electric bikes with little information about who uses them, why they are used, and what factors influence electric bike travel. This

Christopher R Cherry; Robert Cervero

2007-01-01

436

Simulation of electric arc furnace characteristics for voltage flicker study using MATLAB  

Microsoft Academic Search

Power quality is becoming a more concern of today's power system engineer due to the rapid growth of non-linear loads, such as power electronic control equipments and electric arc furnace (EAF). Harmonics and voltage flicker are the power quality problems which are introduced to the power system as result of non-linear behavior of the electric arc furnace operation. Electric arc

D. C. Bhonsle; R. B. Kelkar

2011-01-01

437

Electrical characteristics of an ACF bond as a function of temperature and humidity aging  

Microsoft Academic Search

A commercial Hitachi anisotropic conducting film (ACF) was used to form the electrical interconnection between aluminum pads on a glass plate substrate, and electrolysis tin coated copper pads on a polyimide flexible circuit. These interconnections were aged over 1,400 hours at 85°C and 79% relative humidity. Throughout the thermal aging period a variety of electrical properties were measured. Electrical resistance

J. D. Weidler; R. D. Burg; J. J. Decker; J. H. Constable

2000-01-01

438

Laser-induced breakdown spectroscopy analysis of asbestos  

NASA Astrophysics Data System (ADS)

Laser-induced breakdown spectroscopy was applied to test the possibility of detecting and identifying asbestos in different samples in view of the perspective at field operation without sample preparation which is peculiar to this technique. Several like-resin materials were first investigated by laser-induced breakdown spectroscopy, in order to find an asbestos container assuring safe laboratory operation during the material characterization aimed to identify indicators suitable for a quick identification on field. Successively, spectra of asbestos samples of both in serpentine and amphibole forms were measured and the variability in elemental composition was calculated from the emission spectra. Ratios of intensities of characteristic elements were tested as indicators for asbestos recognition. Laser-induced breakdown spectroscopy results were compared with those obtained by analyzing the same asbestos samples with a scanning electron microscopy equipped with an energy dispersive X-ray spectroscopy, a good correlation was found for Mg/Si and Fe/Si, thus showing the capability of laser-induced breakdown spectroscopy as a diagnostic tool for this category of materials. In particular, it was demonstrated that the method based on two indicators derived from laser-induced breakdown spectroscopy intensity ratios allows to discriminate between asbestos and cements in single shot measurements suitable to field operation.

Caneve, L.; Colao, F.; Fabbri, F.; Fantoni, R.; Spizzichino, V.; Striber, J.

2005-08-01

439

Response of the activization of seismic processes in temporary and spectral characteristics of electric field on Tien-Shan  

NASA Astrophysics Data System (ADS)

We present results of the atmospheric electric field monitoring at the high-altitude Tien-Shan station (43.02 N, 76.56 E, 3340 m above sea level, 20 km from Almaty) and the analysis of its temporal and spectral characteristics during the activization of seismic processes in the vicinity of Almaty since 2007 till 2014. During this period the most considerable seismic activity was observed on May 1-2, 2011 and January 28, 2013. Eight events for 2 days with a magnitude of more than 4.0 occurred on May 1-2, 2011. The main shock of magnitude 5.4 occurred on May 1st at 02:31 UT, 76 km North East of Almaty. Unusual temporal variations of the electric field with amplitude achieving the values of 6-7 kV/m were recorded as during series of earthquakes, and before them (April 28, 30). The duration of the electric field disturbances were 5-12 hours (5 hours on 28.04.2011 and 12 hours on 30.04.2011). Another characteristic of the anomalous variations of the electric field was their positive polarity. The analysis of meteorological and cosmophysical conditions was carried out for the purpose of identification of disturbance sources. It is shown that characteristics of temporal anomalous variations of the electric field don't correspond to these sources of disturbances. It was concluded that the cause of anomalous variations can be sources of the lithospheric origin only. Respectively, anomalies of the electric field can be considered as precursors of earthquakes. We also registered anomalous duration temporal variations of the electric field with the amplitude achieving ±2 kV/m before of the earthquake on January 28, 2013. The main shock of magnitude 6.1 occurred at 16:38 UT, 230 km. to the East from Almaty. The earthquake was felt in Almaty with intensity 4-5 points. In this event as positive variations and with the change of the polarity were recorded. Anomalous variations of electric field before of weaker earthquakes (magnitude < 4) are recorded only for events with coordinates of the epicenter in close proximity to the detector (08.04.2009 and 27.09.2010). Spectral components of anomalous variations of electric field and features of their dynamics before earthquakes were studied. The dominating spectral peaks differing from the background were established. Thus we consider that the atmospheric quasi-static electric field variations are useful for a prediction of earthquakes.

Antonova, Valentina; Zhumabayev, Beibit

2014-05-01

440

The structure of vortex breakdown  

NASA Technical Reports Server (NTRS)

The term 'vortex breakdown', as used in the reported investigation, refers to a disturbance characterized by the formation of an internal stagnation point on the vortex axis, followed by reversed flow in a region of limited axial extent. Two forms of vortex breakdown, which predominate, are shown in photographs. One form is called 'near-axisymmetric' (sometimes 'axisymmetric'), and the other is called 'spiral'. A survey is presented of work published since the 1972 review by Hall. Most experimental data taken since Hall's review have been in tubes, and the survey deals primarily with such cases. It is found that the assumption of axial-symmetry has produced useful results. The classification of flows as supercritical or subcritical, a step that assumes symmetry, has proved universally useful. Experiments show that vortex breakdown is always preceded by an upstream supercritical flow and followed by a subcritical wake. However, a comparison between experiments and attempts at prediction is less than encouraging. For a satisfactory understanding of the structure of vortex breakdown it is apparently necessary to take into account also aspects of asymmetry.

Leibovich, S.

1978-01-01

441

Gauge Theories as Theories of Spontaneous Breakdown.  

National Technical Information Service (NTIS)

Any gauge theory is proved to arise from spontaneous breakdown of symmetry under certain infinite parameter group, the corresponding gauge field being the Goldstone field by which this breakdown is accompanied. (Atomindex citation 09:376918)

E. A. Ivanov V. I. Ogievetskii

1976-01-01

442

Performance characteristics of an electric vehicle lead-acid battery pack at elevated temperatures  

NASA Technical Reports Server (NTRS)

Discharge testing data electric car battery pack over initial electrolyte temperature variations between 27 and 55 C are presented. The tests were conducted under laboratory conditions and then compared to detailed electric vehicle simulation models. Battery discharge capacity increased with temperature for constant current discharges, and battery energy capacity increased with temperature for constant power discharges. Dynamometer tests of the electric test vehicle showed an increase in range of 25% for the higher electrolyte temperature.

Chapman, P.

1982-01-01

443

Performance characteristics of an electric vehicle lead-acid battery pack at elevated temperatures  

NASA Astrophysics Data System (ADS)

Discharge testing data electric car battery pack over initial electrolyte temperature variations between 27 and 55 C are presented. The tests were conducted under laboratory conditions and then compared to detailed electric vehicle simulation models. Battery discharge capacity increased with temperature for constant current discharges, and battery energy capacity increased with temperature for constant power discharges. Dynamometer tests of the electric test vehicle showed an increase in range of 25% for the higher electrolyte temperature.

Chapman, P.

1982-04-01

444

Operating characteristics and modeling of the LLNL 100-kV electric gun  

SciTech Connect

In the electric gun, the explosion of an electrically heated metal foil and the accompanying magnetic forces drive a thin flyer plate up a short barrel. Flyer velocities of up to 18 km/s make the gun useful for hypervelocity impact studies. The authors briefly review the technological evolution of the exploding-metal circuit elements that power the gun, describe the 100-kV electric gun designed at Lawrence Livermore National Laboratory (LLNL) in some detail, and present the general principles of electric gun operation. They compare the experimental performance of the LLNL gun with a simple model and with predictions of a magnetohydrodynamics code.

Osher, J.E.; Barnes, G.; Chau, H.H.; Lee, R.S.; Lee, C.; Speer, R.; Weingart, R.C.

1989-06-01

445

Percolation path and dielectric-breakdown-induced-epitaxy evolution during ultrathin gate dielectric breakdown transient  

Microsoft Academic Search

A physical model has been developed which complies with the experimental observation on the failure mechanism of ultrathin gate oxide breakdown during constant voltage stress. Dynamic equilibrium needs to be established between the percolation conductive path and the dielectric breakdown induced epitaxy (DBIE) formation during gate dielectric breakdown transient. The model is capable of linking the percolation model, soft breakdown,

Chih Hang Tung; Kin Leong Pey; Lei Jun Tang; M. K. Radhakrishnan; Wen He Lin; Felix Palumbo; Salvatore Lombardo

2003-01-01

446

Avoiding breakdown in the CGS algorithm  

Microsoft Academic Search

The conjugate gradient squared algorithm can suffer of similar breakdowns as Lanczos type methods for the same reason that is the non-existence of some formal orthogonal polynomials. Thus curing such breakdowns is possible by jumping over these non-existing polynomials and using only those of them which exist. The technique used is similar to that employed for avoiding breakdowns in Lanczos

Claude Brezinski; Hassane Sadok

1991-01-01

447

Acoustic Characteristics of Hybrid Electric Vehicles and the Safety of Pedestrians Who are Blind.  

National Technical Information Service (NTIS)

Quieter cars such as electric vehicles (EVs) and hybrid electric vehicles (HEVs) may reduce auditory cues used by pedestrians to assess the state of nearby traffic and, as a result, their use may have an adverse impact on pedestrian safety. In order to do...

A. Hastings B. Samiljan C. Scarpone J. K. Pollard L. Garay-Vega

2010-01-01

448

Characteristic Analysis of Temperature Sensor in Dynamic Capacity Increase of High Voltage Electric Power Transmission Lines  

Microsoft Academic Search

Dynamic capacity increase in high voltage electric power transmission line is currently the most economical method for solving electric power transmission bottleneck nowadays. Temperature measurement error of the transmission line will affect the calculated current capacity of the transmission line. In this paper, conductor temperature model was applied to analyze the influence of the measurement error on the maximum current

Yuan Dai; Anqi Song; Wei Wang; Yangchun Cheng; Yongchun Liang; Jianliang Kong; Kai Xiao; Yuning Zhang

2012-01-01

449

Control methods and characteristics of power converter with large capacity for electric railway system  

Microsoft Academic Search

A new type DC electric railway system is under development for high speed and mass transportation in Japan. This system needs large power conversion stations consisting of PWM converters on the ground. The PWM converter is required to supply power stably according to the running conditions of the electric rolling stock. In this system, the PWM converter is required to

Shin-ichi Hase; Takeshi Konishi; Akinobu Okui; Yoshifumi Mochinaga; K. Murata; Shigeo Kawai; Mayumi Sonetaka; H. Sakai; T. Kanai; Y. Tagami; M. Ono; K. Baba

2002-01-01

450

The Explanation of the Photon's Electric and Magnetic Fields; and its Particle and Wave Characteristics  

Microsoft Academic Search

Using the principles of the Vortex Theory, the creation of the photon's electric and magnetic components are explained: the condensed region of space is responsible for creating the photon's electric component and its particle effect; its expansion and contraction is responsible for its frequency; its motion through three dimensional space creates a wave in the surrounding space. This wave is

Russell Moon; Victor Vasiliev

2007-01-01

451

Characteristics of Molten Slag from Hospital Waste Incineration Ash by Electric Arc Furnace  

Microsoft Academic Search

To deal with the issue of hospital solid waste (HSW) incineration ash, ash melting treatment technology was developed in combination with electric arc furnace metallurgical processes. The lab-scale melting experiment of HSW incineration ash, using 2kg DC electric arc furnace, was carried out to provide physical and chemical property analyses of molten slag from the bottom ash alone and the

Liu Han-qiao; Wei Guo-xia; Ye Hui-hua; Zhang Shu-guang

2009-01-01

452

Characteristics of convection of an electrically conducting liquid in an additional external force field  

SciTech Connect

The authors analyze, theoretically and experimentally, the combined effects of gravitational and electric fields along with inertial forces on convective heat and mass transfer in liquid metals undergoing vortex flow in the presence of constant magnetic fields. The experimental data are derived for a eutectic indium-gallium-tin alloy. The flow model incorporates electrical conductivity and Hartmann number as well as other properties.

Mikel'son, A.E.; Karklin, Ya.Kh.

1987-07-01

453

Effect of Surface Nitridation on the Electrical Characteristics of Germanium High-?\\/Metal Gate MetalOxideSemiconductor Devices  

Microsoft Academic Search

We discuss the effect of surface nitridation on germanium high-?\\/metal gate metal-oxide-semiconductor capacitors. Results\\u000a from various groups concerning Ge surface cleaning, surface annealing in ammonia, and the effect of nitridation on C—V and leakage current characteristics are presented and discussed. Electrical data obtained by our group for devices incorporating\\u000a alumina (Al2O3) and hafnia (HfO2) dielectrics is presented and explained. Capacitance-voltage

D. Q. Kelly; J. J.-H. Chen; S. Guha; S. K. Banerjee

454

Effects of high hydrostatic pressure or high intensity electrical field pulse pre-treatment on dehydration characteristics of red paprika  

Microsoft Academic Search

The effects of various pre-treatments (hot water blanching, skin treatments, high pressure and high intensity electric field pulse treatment) on the dehydration characteristics of red paprika (Capsicum annuum L.) were evaluated and compared with untreated samples. Hot water blanching (100°C, 3 min) prior to dehydration (fluidised bed dryer at 60°C, 6 h and 1 m\\/s) resulted in the permeabilisation of

B. I. O Ade-Omowaye; N. K Rastogi; A Angersbach; D Knorr

2001-01-01

455

Electrical Characteristics of High-Performance ZnO Field-Effect Transistors Prepared by Ultrasonic Spray Pyrolysis Technique  

NASA Astrophysics Data System (ADS)

We have fabricated ZnO-based thin-film transistors (TFTs) by low-cost ultrasonic spray pyrolysis. The devices exhibit high saturation mobility of about 0.6 cm2/Vs and on-off current ratio of 105. The electrical characteristics of ZnO-based TFTs show that ultrasonic spray pyrolysis technique can be used as a promising approach to attain high-performance electronic devices. Furthermore, the deposition techniques make the operating process attractive for flexible electronics.

Yi, Ming-Dong; Xie, Ling-Hai; Liu, Yu-Yu; Dai, Yan-Feng; Huang, Jin-Ying

2011-01-01

456

Hot-electron characteristics in chemically resolved electrical measurements of thin silica and SiON layers  

Microsoft Academic Search

We use the recently developed chemically resolved electrical measurements (CREM) to sensitively measure hot-electron transport characteristics in thin dielectric layers. By comparing bare gate-oxide layers, SiO2 and SiON, pronounced differences are revealed that are absent from standard contact measurements and from CREM conducted on top metallic pads. The ``on pad'' and standard measurements obey a similar defect-assisted ``Poole-Frenkel'' transport, whereas

A. Rozenblat; Y. Rosenwaks; H. Cohen

2009-01-01

457

Electrical characteristics and reliability of UV transparent Si3N4 metal-insulator-metal (MIM) capacitors  

Microsoft Academic Search

In this paper, we discuss the electrical characteristics and reliability of UV transparent Si3N4 metal-insulator-metal (MIM) capacitors. We examine film thicknesses in the range of 55 to 25 nm with capacitance densities from 1.2 ff\\/?m2 to 2.8 ff\\/?m2, respectively, for single MIM capacitors. A new approach for projecting the dielectric reliability of these films extends the limits of maximum operating

Ronald J. Bolam; Vidhya Ramachandran; Doug Coolbaugh; Kimball M. Watson

2003-01-01

458

Load control of electrically controlled hydraulic pump's flow\\/pressure characteristics testing with direct drive servo-proportional valve  

Microsoft Academic Search

To obtain a fast, precise and data-comparable flow\\/pressure characteristics test method for electrically controlled hydraulic pump (ECHP), we summarized the disadvantages of the manually-operated throttle valve loading method, which is recommended by ISO 17559-2003, and introduced a new loading method, which loaded the tested ECHPs with direct drive servo-proportional valve (DDV). After analyzing the mathematic model of the DDV loading

Jian-Feng Tao; Lin-Shan Jin; Lei Xu; Cheng-Liang Liu

2010-01-01

459

Electrical stress on electrical steel coatings  

Microsoft Academic Search

This paper reports on investigations of the electrical stress\\/interlaminar voltages on electrical steel coatings and highlights some misconceptions by simulating possible insulation failures in a magnetic core. It concludes by showing that insulation breakdown due to electrical discharge between laminations is not the main cause of short circuits in a magnetic core and questions the significance of insulation resistance consequently,

G. Loisos; A. J Moses; P. Beckley

2003-01-01

460

Oxide breakdown mechanism and quantum physical chemistry for time-dependent dielectric breakdown  

Microsoft Academic Search

Thermochemical-breakdown and hole-induced-breakdown models are theoretically formulated to explain the field-acceleration of TDDB phenomenon. Long-term TDDB test results proved to support the thermochemical-breakdown model. The time-dependent oxide breakdown mechanism is further studied on the basis of quantum physical chemistry. The structural transformations of a-SiO2 up to breakdown are simulated by the semiempirical molecular orbital calculation method (PM3 method) using Si5O16H12

M. Kimura

1997-01-01