dc-plasma-sprayed electronic-tube device

Science.gov (United States)

Meek, T.T.

1982-01-29

An electronic tube and associated circuitry which is produced by dc plasma arc spraying techniques is described. The process is carried out in a single step automated process whereby both active and passive devices are produced at very low cost. The circuitry is extremely reliable and is capable of functioning in both high radiation and high temperature environments. The size of the electronic tubes produced are more than an order of magnitude smaller than conventional electronic tubes.

Dust acoustic waves in a dc glow-discharge plasma

International Nuclear Information System (INIS)

Molotkov, V.I.; Nefedov, A.P.; Torchinskii, V.M.; Fortov, V.E.; Khrapak, A.G.

1999-01-01

The spontaneous excitation of low-frequency oscillations of the macroparticle density in ordered dust structures levitating in standing striations of a dc glow discharge is discovered. It is concluded on the basis of a simplified linear model of an ideal collisionless plasma that the observed instability is caused by the drift motion of ions relative to the dust, which leads to the excitation of dust acoustic oscillations of the plasma

Plasma spheroidization of iron powders in a non-transferred DC thermal plasma jet

International Nuclear Information System (INIS)

Kumar, S.; Selvarajan, V.

2008-01-01

In this paper, the results of plasma spheroidization of iron powders using a DC non-transferred plasma spray torch are presented. The morphology of the processed powders was characterized through scanning electron microscopy (SEM) and optical microscopy (OM). The percentages of spheroidized powders were calculated by the shape factors such as the Irregularity Parameter (IP) and Roundness (RN). A maximum of 83% of spheroidization can be achieved. The spheroidization results are compared with the theoretical estimation and they are found to be in good agreement. The phase composition of the spheroidized powder was analyzed by XRD. The effect of plasma jet temperature and plasma gas flow rate on spheroidization is discussed. At low plasma gas flow rates and at high plasma jet temperatures, the percentage of spheroidization is high

AÇÃO ANTIFÚNGICA DE UM JATO DE PLASMA NÃO-TERMICO DE HÉLIO/AR COMPRIMIDO SOBRE BIOFILMES DE CANDIDA ALBICANS

Directory of Open Access Journals (Sweden)

Fernanda Ramos Figueira

2017-01-01

Full Text Available Os biofilmes fúngicos são uma predominante causa de infecções crônicas associadas à utilização de cateteres e próteses, conferindo resistência aos antibióticos e fatores imunológicos do hospedeiro, sendo as leveduras, do gênero Candida spp, as mais frequentemente isoladas. O plasma não-térmico, operado à pressão atmosférica, vem ganhando destaque como uma nova estratégia antimicrobiana, inclusive para erradicação de biofilmes. Este trabalho teve como objetivo avaliar a eficácia da inativação de biofilmes de Candida albicans ATCC sobre substrato de poliuretano, utilizando jatos de plasma atmosférico de 6L/min de hélio e 4L/min de ar comprimido, alternando entre sistema contínuo e pulsado, com frequência de 60Hz e distâncias de 10 a 30mm entre o bocal e substrato. Após tratamento, realizou-se a contagem das unidades formadoras de colônia e a análise morfológica da superfície do biofilme por Microscopia Eletrônica de Varredura. O melhor grupo foi o plasma de modo pulsado com distância de 30mm com redução de 92% das unidades formadoras de colônia, demonstrando ser uma tecnologia promissora para o controle de biofilmes de C. albicans.

DC Glow Discharge Plasma, Containing Dust Particles: Self Organization and Peculiarities of Behavior

International Nuclear Information System (INIS)

Molotkov, V.I.; Pustyl'nik, M.Y.; Torchinskij, V.M.; Fortov, V.E.

2003-01-01

Dust particles, immersed in a plasma, acquire charge due to which they may be electrostatically trapped in a plasma. The energy of the interaction of the dust particles may be enough to transfer the dust component to nonideal and even crystalline state. This phenomenon is observed in various plasmas. In the present work a review of the investigations of strongly nonideal dusty plasma of the dc glow discharge striations is given. The formation of plasma crystals, liquids and plasma liquid crystals is considered. Typical phenomenon a for the dc discharge dusty plasma, such as coexistence of different phases in a single structure, convective motions, dust acoustic instability, are underlined. Results of the experiments on different external influences on dusty plasma structures are stated. It is shown that external influences may be used for measuring of the particle charge and field of forces acting on a dust grain levitating in a plasma. (author)

Dynamics of runaway tails with time-dependent sub-Dreicer dc fields in magnetized plasmas

International Nuclear Information System (INIS)

Moghaddam-Taaheri, E.; Vlahos, L.

1987-01-01

The evolution of runaway tails driven by sub-Dreicer time-dependent dc fields in a magnetized plasma are studied numerically using a quasilinear code based on the Ritz--Galerkin method and finite elements. It is found that the runaway tail maintained a negative slope during the dc field increase. Depending on the values of the dc electric field at t = 0 and the electron gyrofrequency to the plasma frequency ratio the runaway tail became unstable to the anomalous Doppler resonance or remained stable before the saturation of the dc field at some maximum value. The systems that remained stable during this stage became unstable to the anomalous Doppler or the Cerenkov resonances when the dc field was kept at the saturation level or decreased. Once the instability is triggered, the runaway tail is isotropized

Dynamics of runaway tails with time-dependent sub-Dreicer dc fields in magnetized plasmas

Science.gov (United States)

Moghaddam-Taaheri, E.; Vlahos, L.

1987-01-01

The evolution of runaway tails driven by sub-Dreicer time-dependent dc fields in a magnetized plasma are studied numerically using a quasi-linear code based on the Ritz-Galerkin method and finite elements. It is found that the runaway tail maintained a negative slope during the dc field increase. Depending on the values of the dc electric field at t = 0 and the electron gyrofrequency to the plasma frequency ratio the runaway tail became unstable to the anomalous Doppler resonance or remained stable before the saturation of the dc field at some maximum value. The systems that remained stable during this stage became unstable to the anomalous Doppler or the Cerenkov resonances when the dc field was kept at the saturation level or decreased. Once the instability is triggered, the runaway tail is isotropized.

Study of the physical discharge properties of a Ar/O2 DC plasma jet

Science.gov (United States)

Barkhordari, A.; Ganjovi, A.; Mirzaei, I.; Falahat, A.

2018-03-01

In this paper, the physical properties of plasma discharge in a manufactured DC plasma jet operating with the Ar/O2 gaseous mixture are studied. Moreover, the optical emission spectroscopy technique is used to perform the experimental measurements. The obtained emission spectra are analyzed and, the plasma density, rotational, vibrational and electronic temperature are calculated. The NO emission lines from {NO }γ( A2 Σ^{+} \\to {X}2 Πr ) electronic transition are observed. It is seen that, at the higher argon contributions in Ar/O2 gaseous mixture, the emission intensities from argon ions will increase. Moreover, while the vibrational and excitation temperatures are increased at the higher input DC currents, they will decrease at the higher Ar percentages in the Ar/O2 gaseous mixture. Furthermore, at the higher DC currents and Ar contributions, both the plasma electron density and dissociation fraction of oxygen atoms are increased.

Simulation Study of an Extended Density DC Glow Toroidal Plasma Source

International Nuclear Information System (INIS)

Granda-Gutierrez, E. E.; Piedad-Beneitez, A. de la; Lopez-Callejas, R.; Godoy-Cabrera, O. G.; Benitez-Read, J. S.; Pacheco-Sotelo, J. O.; Pena-Eguiluz, R.; Mercado-Cabrera, A.; Valencia A, R.; Barocio, S. R.

2006-01-01

Conventional wisdom assigns the DC glow discharge regime to plasma currents below ∼500 mA values, beyond which the discharge falls into the anomalous glow and the turbulent arc regimes. However, we have found evidence that, during toroidal discharges, this barrier can be ostensibly extended up to 800 mA. Thus, a computer simulation has been applied to the evolution of the main electrical characteristics of such a glow discharge plasma in a toroidal vessel in order to design and construct a respective voltage/current controlled source. This should be able to generate a DC plasma in the glow regime with which currents in the range 10-3-100 A can be experimented and 109-1010 cm-3 plasma densities can be achieved to PIII optimization purposes. The plasma is modelled as a voltage-controlled current source able to be turned on whenever the breakdown voltage is reached across the gap between the anode and the vessel wall. The simulation outcome fits well our experimental measurements showing that the plasma current obeys power laws that are dependent on the power current and other control variables such as the gas pressure

Synthesis of zinc oxide nanoparticles by dc arc dusty plasma

Energy Technology Data Exchange (ETDEWEB)

Senthilkumar, K., E-mail: akskumar.phy@gmail.com; Senthilkumar, O. [Shimane University, Research Project Promotion Institute (Japan); Morito, S.; Ohba, T.; Fujita, Y. [Shimane University, Interdisciplinary Graduate School of Science and Engineering (Japan)

2012-10-15

Optical emission signals of a dc arc plasma system that was used for generating ZnO nanoparticles (NPs) have been investigated in gas phase as a function of chamber pressure and arc current. In this technique, a commercially available zinc 4N rod is used as a zinc source, as well as anode in the dc circuit and ambient air as an oxygen source. A carbon rod acts as the cathode. The optical transitions of Zn(I) and O(I) in addition, excitation of high energy states of N{sub 2}, CN, and atomic nitrogen lines were observed in OES due to increase of electron temperature than gas temperature (T{sub e} > T{sub g}) by reducing the chamber pressure from 760 torr to lower pressures. The as-prepared NPs show good crystalline quality with hexagonal wurtzite structure and the particle size was ranging from few nm to 100 nm in the form of rod and spherical morphologies. The impurity nature and structural properties of as-prepared NPs by dc arc plasma experiments were correlated with OES and Raman spectroscopy.

Synthesis of zinc oxide nanoparticles by dc arc dusty plasma

International Nuclear Information System (INIS)

Senthilkumar, K.; Senthilkumar, O.; Morito, S.; Ohba, T.; Fujita, Y.

2012-01-01

Optical emission signals of a dc arc plasma system that was used for generating ZnO nanoparticles (NPs) have been investigated in gas phase as a function of chamber pressure and arc current. In this technique, a commercially available zinc 4N rod is used as a zinc source, as well as anode in the dc circuit and ambient air as an oxygen source. A carbon rod acts as the cathode. The optical transitions of Zn(I) and O(I) in addition, excitation of high energy states of N 2 , CN, and atomic nitrogen lines were observed in OES due to increase of electron temperature than gas temperature (T e > T g ) by reducing the chamber pressure from 760 torr to lower pressures. The as-prepared NPs show good crystalline quality with hexagonal wurtzite structure and the particle size was ranging from few nm to 100 nm in the form of rod and spherical morphologies. The impurity nature and structural properties of as-prepared NPs by dc arc plasma experiments were correlated with OES and Raman spectroscopy.

Direct measurements of particle transport in dc glow discharge dusty plasmas

International Nuclear Information System (INIS)

Thomas, E. Jr.

2001-01-01

Many recent experiments in dc glow discharge plasmas have shown that clouds of dust particles can be suspended near the biased electrodes. Once formed, the dust clouds have well defined boundaries while particle motion within the clouds can be quite complex. Because the dust particles in the cloud can remain suspended in the plasma for tens of minutes, it implies that the particles have a low diffusive loss rate and follow closed trajectories within the cloud. In the experiments discussed in this paper, direct measurements of the dust particle velocities are made using particle image velocimetry (PIV) techniques. From the velocity measurements, a reconstruction of the three-dimensional transport of the dust particles is performed. A qualitative model is developed for the closed motion of the dust particles in a dc glow discharge dusty plasma. (orig.)

Relationship between the DC Bias and Debye Length in a Complex Plasma

OpenAIRE

Kong, Jie; Reyes, Jorge C.; Creel, James; Hyde, Truell

2007-01-01

The levitation height of a dust particle layer within a RF discharge plasma sheath is known to be related to the DC bias, the background pressure, and the Debye length. In this paper, a new experimental technique for measurement of the Debye length is introduced. This technique is based on the relationship between an externally applied DC bias and the particle levitation height and shows that under appropriate conditions, the addition of an externally applied DC bias provides a mechanism for ...

Characterization of DC argon plasma jet at atmospheric pressure

International Nuclear Information System (INIS)

Yan Jianhua; Ma Zengyi; Pan Xinchao; Cen Kefa; Bruno, C

2006-01-01

An original DC double anode plasma torch operating with argon at atmospheric pressure which provides a long time and highly stable plasma jet is analyzed through its electrical and optical signals. Effects of gas flow rate and current intensity on the arc dynamics behaviour are studied using standard diagnostic tools such as FFT and correlation function. An increasing current-voltage characteristic is reported for different argon flow rates. It is noted that the takeover mode is characteristic for argon plasma jet and arc fluctuations in our case are mainly induced by the undulation of torch power supply. Furthermore, the excitation temperatures and electron densities of the plasma jet inside and outside the arc chamber have been determined by means of optical emission spectroscopy (OES). The criteria for the existence of local thermodynamic equilibrium (LTE) in plasma is then discussed. The results show that argon plasma jet at atmospheric pressure under our experimental conditions is close to LTE. (authors)

Effect of Fluctuations of DC Current on Properties of Plasma Jet Generated in Plasma Spraying Torch with Gerdien Arc

Czech Academy of Sciences Publication Activity Database

Hrabovský, Milan; Kopecký, Vladimír; Chumak, Oleksiy; Kavka, Tetyana; Mašláni, Alan; Sember, Viktor; Ctibor, Pavel

2009-01-01

Roč. 13, č. 2 (2009), s. 229-240 ISSN 1093-3611 Institutional research plan: CEZ:AV0Z20430508 Keywords : Plasma torch * dc arc * plasma jet * fluctuations * plasma spraying Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.333, year: 2009 http://www.begellhouse.com/journals/57d172397126f956,4e2a92412d8c6bb5.html

DC Thermal Plasma Design and Utilization for the Low Density Polyethylene to Diesel Oil Pyrolysis Reaction

Directory of Open Access Journals (Sweden)

Hossam A. Gabbar

2017-06-01

Full Text Available The exponential increase of plastic production produces 100 million tonnes of waste plastics annually which could be converted into hydrocarbon fuels in a thermal cracking process called pyrolysis. In this research work, a direct current (DC thermal plasma circuit is designed and used for conversion of low density polyethylene (LDPE into diesel oil in a laboratory scale pyrolysis reactor. The experimental setup uses a 270 W DC thermal plasma at operating temperatures in the range of 625 °C to 860 °C for a low density polyethylene (LDPE pyrolysis reaction at pressure = −0.95, temperature = 550 °C with τ = 30 min at a constant heating rate of 7.8 °C/min. The experimental setup consists of a vacuum pump, closed system vessel, direct current (DC plasma circuit, and a k-type thermocouple placed a few millimeters from the reactant sample. The hydrocarbon products are condensed to diesel oil and analyzed using flame ionization detector (FID gas chromatography. The analysis shows 87.5% diesel oil, 1,4-dichlorobenzene (Surr, benzene, ethylbenzene and traces of toluene and xylene. The direct current (DC thermal plasma achieves 56.9 wt. % of diesel range oil (DRO, 37.8 wt. % gaseous products and minimal tar production. The direct current (DC thermal plasma shows reliability, better temperature control, and high thermal performance as well as the ability to work for long operation periods.

Three-dimensional modelling of a dc non-transferred arc plasma torch

International Nuclear Information System (INIS)

Li Heping; Chen Xi

2001-01-01

Three-dimensional (3D) modelling results are presented concerning a direct current (dc) non-transferred arc plasma torch with axisymmetrical geometrical configuration and axisymmetrical boundary conditions. It is shown that the arc is locally attached at the anode surface of the plasma torch, and the heat transfer and plasma flow within the torch are of 3D features. The predicted arc root location at the anode surface and arc voltage of the torch are very consistent with corresponding experimental results. (author)

Characteristics and Thermal Efficiency of a Non-transferred DC Plasma Spraying Torch Under Low Pressure

International Nuclear Information System (INIS)

Bao Shicong; Ye Minyou; Zhang Xiaodong; Guo Wenkang; Xu Ping

2008-01-01

Current-voltage (I-V) characteristics of a non-transferred DC arc plasma spray torch operated in argon at vacuum are reported. The arc voltage is of negative characteristics for a current below 200 A, flat for a current between 200 A to 250 A and positive for a current beyond 250 A. The voltage increases slowly with the increase in carrier gas of arc. The rate of change in voltage with currents is about 3∼4 V/100 A at a gas flow rate of about 1∼1.5 V/10 standard liter per minute (slpm). The I-V characteristics of the DC plasma torch are of a shape of hyperbola. Arc power increases with the argon flow rate, and the thermal efficiency of the torch acts in a similar way. The thermal efficiency of the non-transferred DC plasmatron is about 65∼78%. (low temperature plasma)

Investigation on Plasma Jet Flow Phenomena During DC Air Arc Motion in Bridge-Type Contacts

Science.gov (United States)

Zhai, Guofu; Bo, Kai; Chen, Mo; Zhou, Xue; Qiao, Xinlei

2016-05-01

Arc plasma jet flow in the air was investigated under a bridge-type contacts in a DC 270 V resistive circuit. We characterized the arc plasma jet flow appearance at different currents by using high-speed photography, and two polished contacts were used to search for the relationship between roughness and plasma jet flow. Then, to make the nature of arc plasma jet flow phenomena clear, a simplified model based on magnetohydrodynamic (MHD) theory was established and calculated. The simulated DC arc plasma was presented with the temperature distribution and the current density distribution. Furthermore, the calculated arc flow velocity field showed that the circular vortex was an embodiment of the arc plasma jet flow progress. The combined action of volume force and contact surface was the main reason of the arc jet flow. supported by National Natural Science Foundation of China (Nos. 51307030, 51277038)

Acoustic signature analysis of the interaction between a dc plasma jet and a suspension liquid jet

International Nuclear Information System (INIS)

Rat, V; Coudert, J F

2009-01-01

Suspension plasma spraying allows forming finely structured coatings by injecting suspensions of ceramic particles within a dc plasma jet. The electric arc motion in dc plasma torch is the main acoustic source which is modified by the injection of suspension. The analyses of cross-correlations between the arc voltage and the acoustic signal show a decrease in time propagations due to local cooling of the plasma jet when injecting suspensions. Moreover, power spectra highlight acoustic amplifications below a certain frequency threshold and attenuations above. A simplified model of the frequency acoustic response of a two-phase vaporizing mixture is used to interpret experimental measurements. These acoustic effects are due to the dynamics of thermal transfers between vaporizing liquid and plasma.

A dc non-thermal atmospheric-pressure plasma microjet

Science.gov (United States)

Zhu, WeiDong; Lopez, Jose L.

2012-06-01

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

A dc non-thermal atmospheric-pressure plasma microjet

International Nuclear Information System (INIS)

Zhu Weidong; Lopez, Jose L

2012-01-01

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

DC-driven plasma gun: self-oscillatory operation mode of atmospheric-pressure helium plasma jet comprised of repetitive streamer breakdowns

Science.gov (United States)

Wang, Xingxing; Shashurin, Alexey

2017-02-01

This paper presents and studies helium atmospheric pressure plasma jet comprised of a series of repetitive streamer breakdowns, which is driven by pure DC high voltage (self-oscillatory behavior). The repetition frequency of the breakdowns is governed by the geometry of discharge electrodes/surroundings and gas flow rate. Each next streamer is initiated when the electric field on the anode tip recovers after the previous breakdown and reaches the breakdown threshold value of about 2.5 kV cm-1. One type of the helium plasma gun designed using this operational principle is demonstrated. The gun operates on about 3 kV DC high voltage and is comprised of the series of the repetitive streamer breakdowns at a frequency of about 13 kHz.

Calculation of DC Arc Plasma Torch Voltage- Current Characteristics Based on Steebeck Model

International Nuclear Information System (INIS)

Gnedenko, V.G.; Ivanov, A.A.; Pereslavtsev, A.V.; Tresviatsky, S.S.

2006-01-01

The work is devoted to the problem of the determination of plasma torches parameters and power sources parameters (working voltage and current of plasma torch) at the predesigning stage. The sequence of calculation of voltage-current characteristics of DC arc plasma torch is proposed. It is shown that the simple Steenbeck model of arc discharge in cylindrical channel makes it possible to carry out this calculation. The results of the calculation are confirmed by the experiments

Epidemiología molecular de infección nosocomial por Klebsiella pneumoniae productora de beta-lactamasas de espectro extendido.

Directory of Open Access Journals (Sweden)

Paula Andrea Espinal

2004-09-01

Full Text Available La epidemiología molecular aplicada al estudio de las infecciones nosocomiales ha sido fundamental para la formulación y la evaluación de las medidas de control; con este fin, se caracterizaron microbiológica y molecularmente aislamientos de Klebsiella pneumoniae productores de beta-lactamasas de espectro extendido (BLEE obtenidos de pacientes en un hospital de tercer nivel de Bogotá, D.C., Colombia. Se tipificaron quince aislamientos por electroforesis en gel de campo pulsado (PFGE y por amplificación de secuencias de ADN repetidas (REP-PCR. La susceptibilidad antimicrobiana y la producción de BLEE se determinaron de acuerdo con las normas de NCCLS. Las beta-lactamasas se evaluaron por isoelectroenfoque y PCR. El 80% de estos aislamientos se asociaron con infección nosocomial y de éstos, el 91,7% provenía de unidades de cuidado intensivo. La susceptibilidad antibiótica mostró 13 patrones de resistencia; 87% de los aislamientos presentó corresistencia a amikacina, 53% a gentamicina, 33,3% a ciprofloxacina, 40% a cefepime, 66,7% a piperacilina/tazobactam, 60% trimetoprim/sulfametoxazol y 46,7% a cloranfenicol. Todos fueron sensibles a imipenem. En la mayoría de los aislamientos se detectó producción simultánea de beta-lactamasas del tipo TEM y SHV y el 93,3% produjo ceftazidimasa de pI 8.2 del tipo SHV-5. Los 15 aislamientos fueron agrupados por PFGE y REP-PCR en 11 y 12 patrones electroforéticos, respectivamente. Esta variabilidad genética está relacionada con infecciones nosocomiales de origen endógeno más que por infecciones cruzadas.

Discharge Characteristics of DC Arc Water Plasma for Environmental Applications

International Nuclear Information System (INIS)

Choi, Sooseok; Watanabe, Takayuki; Li Tianming

2012-01-01

A water plasma was generated by DC arc discharge with a hafnium embedded rod-type cathode and a nozzle-type anode. The discharge characteristics were examined by changing the operation parameter of the arc current. The dynamic behavior of the arc discharge led to significant fluctuations in the arc voltage and its frequency. Analyses of the high speed image and the arc voltage waveform showed that the arc discharge was in the restrike mode and its frequency varied within several tens of kilohertz according to the operating conditions. The larger thermal plasma volume was generated by the higher flow from the forming steam with a higher restrike frequency in the higher arc current conditions. In addition, the characteristics of the water plasma jet were investigated by means of optical emission spectroscopy to identify the abundant radicals required in an efficient waste treatment process. (plasma technology)

Numerical simulation of a DC double anode arc plasma torch

International Nuclear Information System (INIS)

Chen Lunjiang; Tang Deli; Zhu Hailong

2012-01-01

A 2D axisymmetric numerical simulation of DC double anode plasma torch was done by the computational fluid dynamics (CFD) software FLUENT to improve the efficiency of the waste treatment, which is on the basis of the magnetic fluid dynamics (MHD) theory and uses the method of magnetic vector potential, and the simulation method is based on SIMPLE algorithm. The temperature and speed distributions of the plasma, and so on were obtained. The results show that the temperature of plasma decreases with increasing the axial distance, and increases with increasing the amplitude of the arc current. The velocity first increases and then decreases with the axial distance increase, and increase with the arc current increase. The temperature and the speed at the export of the plasma torch both decrease when the radial distance increases. Those results are in agreement with the experimental results. (authors)

Cold atmospheric plasma jet in an axial DC electric field

Energy Technology Data Exchange (ETDEWEB)

Lin, Li, E-mail: lilin@gwu.edu, E-mail: keidar@gwu.edu; Keidar, Michael, E-mail: lilin@gwu.edu, E-mail: keidar@gwu.edu [Department of Mechanical and Aerospace Engineering, School of Engineering and Applied Science, The George Washington University, Washington, DC 20052 (United States)

2016-08-15

Cold atmospheric plasma (CAP) jet is currently intensively investigated as a tool for new and potentially transformative cancer treatment modality. However, there are still many unknowns about the jet behavior that requires attention. In this paper, a helium CAP jet is tested in an electrostatic field generated by a copper ring. Using Rayleigh microwave scattering method, some delays of the electron density peaks for different ring potentials are observed. Meanwhile, a similar phenomenon associated with the bullet velocity is found. Chemical species distribution along the jet is analyzed based on the jet optical emission spectra. The spectra indicate that a lower ring potential, i.e., lower DC background electric field, can increase the amount of excited N{sub 2}, N{sub 2}{sup +}, He, and O in the region before the ring, but can decrease the amount of excited NO and HO almost along the entire jet. Combining all the results above, we discovered that an extra DC potential mainly affects the temporal plasma jet properties. Also, it is possible to manipulate the chemical compositions of the jet using a ring with certain electric potentials.

Challenges in process integration of catalytic DC plasma synthesis of vertically aligned carbon nanofibres

International Nuclear Information System (INIS)

Melechko, Anatoli V; Pearce, Ryan C; Hensley, Dale K; Simpson, Michael L; McKnight, Timothy E

2011-01-01

The ability to synthesize free-standing, individual carbon nanofibres (CNFs) aligned perpendicularly to a substrate has enabled fabrication of a large array of devices with nanoscale functional elements, including electron field emission sources, electrochemical probes, neural interface arrays, scanning probes, gene delivery arrays and many others. This was made possible by development of a catalytic plasma process, with DC bias directing the alignment of nanofibres. Successful implementation of prototypical devices has uncovered numerous challenges in the integration of this synthesis process as one of the steps in device fabrication. This paper is dedicated to these engineering and fundamental difficulties that hinder further device development. Relatively high temperature for catalytic synthesis, electrical conductivity of the substrate to maintain DC discharge and other difficulties place restrictions on substrate material. Balancing non-catalytic carbon film deposition and substrate etching, non-uniformity of plasma due to growth of the high aspect ratio structures, plasma instabilities and other factors lead to challenges in controlling the plasma. Ultimately, controlling the atomistic processes at the catalyst nanoparticle (NP) and the behaviour of the NP is the central challenge of plasma nanosynthesis of vertically aligned CNFs.

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

Science.gov (United States)

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

2017-01-01

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

dc-Hydrogen plasma induced defects in bulk n-Ge

Energy Technology Data Exchange (ETDEWEB)

Nyamhere, C., E-mail: cloud.nyamhere@nmmu.ac.za [Department of Physics, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031 (South Africa); Venter, A.; Murape, D.M. [Department of Physics, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031 (South Africa); Auret, F.D.; Coelho, S.M.M. [Department of Physics, University of the Pretoria, Lynnwood Road, Pretoria 0002 (South Africa); Botha, J.R. [Department of Physics, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031 (South Africa)

2012-08-01

Bulk antimony doped germanium (n-Ge) has been exposed to a dc-hydrogen plasma. Capacitance-voltage depth profiles revealed extensive near surface passivation of the shallow donors as evidenced by {approx}a 1.5 orders of magnitude reduction in the free carrier concentration up to depth of {approx}3.2 {mu}m. DLTS and Laplace-DLTS revealed a prominent electron trap 0.30 eV below the conduction (E{sub C} -0.30 eV). The concentration of this trap increased with plasma exposure time. The depth profile for this defect suggested a uniform distribution up to 1.2 {mu}m. Annealing studies show that this trap, attributed to a hydrogen-related complex, is stable up to 200 Degree-Sign C. Hole traps, or vacancy-antimony centers, common in this material after high energy particle irradiation, were not observed after plasma exposure, an indication that this process does not create Frenkel (V-I) pairs.

dc-Hydrogen plasma induced defects in bulk n-Ge

International Nuclear Information System (INIS)

Nyamhere, C.; Venter, A.; Murape, D.M.; Auret, F.D.; Coelho, S.M.M.; Botha, J.R.

2012-01-01

Bulk antimony doped germanium (n-Ge) has been exposed to a dc-hydrogen plasma. Capacitance-voltage depth profiles revealed extensive near surface passivation of the shallow donors as evidenced by ∼a 1.5 orders of magnitude reduction in the free carrier concentration up to depth of ∼3.2 μm. DLTS and Laplace-DLTS revealed a prominent electron trap 0.30 eV below the conduction (E C -0.30 eV). The concentration of this trap increased with plasma exposure time. The depth profile for this defect suggested a uniform distribution up to 1.2 μm. Annealing studies show that this trap, attributed to a hydrogen-related complex, is stable up to 200 °C. Hole traps, or vacancy-antimony centers, common in this material after high energy particle irradiation, were not observed after plasma exposure, an indication that this process does not create Frenkel (V-I) pairs.

Study of aerosol sample interaction with dc plasma in the presence of oscillating magnetic field

International Nuclear Information System (INIS)

Stoiljkovic, M.M.; Pavlovic, M.S.; Savovic, J.; Kuzmanovic, M.; Marinkovic, M.

2005-01-01

Oscillating magnetic field was used to study the efficiency of the aerosol sample introduction into the dc plasma. At atmospheric plasmas, the effect of magnetic field is reduced to Lorentz forces on the current carrying plasma, which produces motion of the plasma. The motion velocity of dc plasma caused by oscillating magnetic field was correlated to spectral emission enhancement of analytes introduced as aerosols. Emission enhancement is the consequence of the reduced barrier to introduction of analyte species and aerosol particles into the hot plasma region. Two hypotheses described in the literature for the origin of the barrier are considered: (i) barrier induced by temperature field is based upon the thermophoretic forces on the aerosol particles when their radius is comparable to the molecular free path in the surrounding gas and (ii) barrier induced by radial electric field, recently described, that originates from gradients of charged particles in radial direction. Correlation between ionization energy of the analyte atoms with experimental emission enhancement obtained by the use of oscillating magnetic field indicates that mechanism (ii) based upon the radial electric field is predominant. The ultimate emission enhancement and possible analytical advantage is discussed

Discharge Characteristics of DC Arc Water Plasma for Environmental Applications

Science.gov (United States)

Li, Tianming; Sooseok, Choi; Takayuki, Watanabe

2012-12-01

A water plasma was generated by DC arc discharge with a hafnium embedded rod-type cathode and a nozzle-type anode. The discharge characteristics were examined by changing the operation parameter of the arc current. The dynamic behavior of the arc discharge led to significant fluctuations in the arc voltage and its frequency. Analyses of the high speed image and the arc voltage waveform showed that the arc discharge was in the restrike mode and its frequency varied within several tens of kilohertz according to the operating conditions. The larger thermal plasma volume was generated by the higher flow from the forming steam with a higher restrike frequency in the higher arc current conditions. In addition, the characteristics of the water plasma jet were investigated by means of optical emission spectroscopy to identify the abundant radicals required in an efficient waste treatment process.

Modelling chemical reactions in dc plasma inside oxygen bubbles in water

International Nuclear Information System (INIS)

Takeuchi, N; Ishii, Y; Yasuoka, K

2012-01-01

Plasmas generated inside oxygen bubbles in water have been developed for water purification. Zero-dimensional numerical simulations were used to investigate the chemical reactions in plasmas driven by dc voltage. The numerical and experimental results of the concentrations of hydrogen peroxide and ozone in the solution were compared with a discharge current between 1 and 7 mA. Upon increasing the water vapour concentration inside bubbles, we saw from the numerical results that the concentration of hydrogen peroxide increased with discharge current, whereas the concentration of ozone decreased. This finding agreed with the experimental results. With an increase in the discharge current, the heat flux from the plasma to the solution increased, and a large amount of water was probably vaporized into the bubbles.

Modelling chemical reactions in dc plasma inside oxygen bubbles in water

Science.gov (United States)

Takeuchi, N.; Ishii, Y.; Yasuoka, K.

2012-02-01

Plasmas generated inside oxygen bubbles in water have been developed for water purification. Zero-dimensional numerical simulations were used to investigate the chemical reactions in plasmas driven by dc voltage. The numerical and experimental results of the concentrations of hydrogen peroxide and ozone in the solution were compared with a discharge current between 1 and 7 mA. Upon increasing the water vapour concentration inside bubbles, we saw from the numerical results that the concentration of hydrogen peroxide increased with discharge current, whereas the concentration of ozone decreased. This finding agreed with the experimental results. With an increase in the discharge current, the heat flux from the plasma to the solution increased, and a large amount of water was probably vaporized into the bubbles.

Improvement of In-Flight Alumina Spheroidization Process Using a Small Power Argon DC-RF Hybrid Plasma Flow System by Helium Mixture

Science.gov (United States)

Takana, Hidemasa; Jang, Juyong; Igawa, Junji; Nakajima, Tomoki; Solonenko, Oleg P.; Nishiyama, Hideya

2011-03-01

For the further improvement of in-flight alumina spheroidization process with a low-power direct-current radiofrequency (DC-RF) hybrid plasma flow system, the effect of a small amount of helium gas mixture in argon main gas and also the effect of increasing DC nozzle diameter on powder spheroidization ratio have been experimentally clarified with correlating helium gas mixture percentage, plasma enthalpy, powder in-flight velocity, and temperature. The alumina spheroidization ratio increases by helium gas mixture as a result of enhancement of plasma enthalpy. The highest spheroidization ratio is obtained by 4% mixture of helium in central gas with enlarging nozzle diameter from 3 to 4 mm, even under the constant low input electric power given to a DC-RF hybrid plasma flow system.

Resonant Excitation of Boundary Layer Instability of DC Arc Plasma Jet by Current Modulation

Czech Academy of Sciences Publication Activity Database

Kopecký, Vladimír; Hrabovský, Milan

2011-01-01

Roč. 31, č. 6 (2011), s. 827-838 ISSN 0272-4324 R&D Projects: GA ČR GAP205/11/2070 Institutional research plan: CEZ:AV0Z20430508 Keywords : dc arc jet * plasma jet oscillations * boundary layer instability * frequency spectra Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.602, year: 2011 http://www.springerlink.com/content/v160841757161758/

The study on diamond-coated insert by DC plasma jet CVD

International Nuclear Information System (INIS)

Zhou Kesong; Dai Mingjiang; Song Jinbing; Kuang Tongchun; Liu Zhengyi

2001-01-01

Diamond coating were deposited on cemented carbide inserts by DC plasma jet CVD. The cemented carbide inserts were pretreated by methods including chemical etching of Co, Ar/H 2 plasma etching. The characteristics of diamond film, interface structure, adhesion strength and film stress were analysized by different methods such as SEM, XRD, Raman spectrum etc. A comparing experiment of cutting Al - 22 % Si alloy was carried out with diamond-coated cemented carbide inserts and uncoated cemented carbide inserts. The results show that the diamond-coated cemented carbide insert has a great advantage for cutting abrasive high content Al - Si alloy. (author)

Control of plasma layer in a fusion reactor correlated to DC motor control using PSO-ANFIS

International Nuclear Information System (INIS)

Mahapatra, Sakuntala; Daniel, Raju; Dey, Deep Narayan

2013-01-01

Plasma position and shape control is very crucial for the overall performance of the fusion reactor such as Tokamak. The quality of the discharge in the Saskatchewan TORus-Modified (STOR-M) tokamak is strongly related to the position of the plasma column within the discharge vessel. If the plasma column approaches too near the wall, then either minor or complete disruption occurs. Consequently it is necessary to be able to control dynamically the position of the plasma column throughout the entire discharge. Now a day's most fusion reactor employs the traditional PID controller for the confinement of plasma layer. Fuzzy logic is used for the control of Plasma layer. In this paper we have used the hybrid of PSO-ANFIS technique to control the speed of a DC motor. We have used two input parameters like speed, torque and output is firing angle. In our work first order Sugeno fuzzy model is taken with three rules and the parameters of Gaussian membership function is controlled by the PSO technique. PSO-ANFIS speed controller obtains better dynamic behavior and superior performance of the DC motor speed control. Similar approach can be correlated to the control of plasma layer. For the plasma control two inputs can be taken as plasma position ΔH and the plasma current and the single output, the control decision u(t). (author)

Silica nanoparticles produced by DC arc plasma from a solid raw materials

Science.gov (United States)

Kosmachev, P. V.; Vlasov, V. A.; Skripnikova, N. K.

2017-05-01

Plasma synthesis of SiO2 nanoparticles in experimental atmospheric pressure plasma reactor on the basis of DC arc plasma generator was presented in this paper. Solid high-silica raw materials such as diatomite from Kamyshlovskoye deposit in Russia, quartzite from Chupinskoye deposit in Russia and milled window glass were used. The obtained nanoparticles were characterized based on their morphology, chemical composition and size distribution. Scanning electron microscopy, laser diffractometry, nitrogen absorption (Brunauer-Emmett-Teller method), X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy were used to characterize the synthesized products. The obtained silica nanoparticles are agglomerated, have spherical shape and primary diameters between 10-300 nm. All samples of synthesized nanopowders were compared with commercial nanopowders.

Advancement of In-Flight Alumina Powder Spheroidization Process with Water Droplet Injection Using a Small Power DC-RF Hybrid Plasma Flow System

Science.gov (United States)

Jang, Juyong; Takana, Hidemasa; Park, Sangkyu; Nishiyama, Hideya

2012-09-01

The correlation between plasma thermofluid characteristics and alumina powder spheroidization processes with water droplet injection using a small power DC-RF hybrid plasma flow system was experimentally clarified. Micro-sized water droplets with a low water flow rate were injected into the tail of thermal plasma flow so as not to disturb the plasma flow directly. Injected water droplets were vaporized in the thermal plasma flow and were transported upstream in the plasma flow to the torch by the backflow. After dissociation of water, the production of hydrogen was detected by the optical emission spectroscopy in the downstream RF plasma flow. The emission area of the DC plasma jet expanded and elongated in the vicinity of the RF coils. Additionally, the emission area of RF plasma flow enlarged and was visible as red emission in the downstream RF plasma flow in the vicinity below the RF coils due to hydrogen production. Therefore, the plasma flow mixed with produced hydrogen increased the plasma enthalpy and the highest spheroidization rate of 97% was obtained at a water flow rate of 15 Sm l/min and an atomizing gas flow rate of 8 S l/min using a small power DC-RF hybrid plasma flow system.

Surface modification of 17-4PH stainless steel by DC plasma nitriding and titanium nitride film duplex treatment

International Nuclear Information System (INIS)

Qi, F.; Leng, Y.X.; Huang, N.; Bai, B.; Zhang, P.Ch.

2007-01-01

17-4PH stainless steel was modified by direct current (DC) plasma nitriding and titanium nitride film duplex treatment in this study. The microstructure, wear resistance and corrosion resistance were characterized by X-ray diffraction (XRD), pin-on-disk tribological test and polarization experiment. The results revealed that the DC plasma nitriding pretreatment was in favor of improving properties of titanium nitride film. The corrosion resistance and wear resistance of duplex treatment specimen was more superior to that of only coated titanium nitride film

Treatment of refractory powders by a novel, high enthalpy dc plasma

Science.gov (United States)

Pershin, L.; Mitrasinovic, A.; Mostaghimi, J.

2013-06-01

Thermophysical properties of CO2-CH4 mixtures at high temperatures are very attractive for materials processing. In comparison with argon, at the same temperature, such a mixture possesses much higher enthalpy and higher thermal conductivity. At high temperatures, CO2-CH4 mixture has a complex composition with strong presence of CO which, in the case of powder treatment, could reduce oxidation. In this work, a dc plasma torch with graphite cathode was used to study the effect of plasma gas composition on spheroidization of tungsten carbide and alumina powders. Two different gas compositions were used to generate the plasma while the torch current was kept at 300 A. Various techniques were employed to assess the average concentration of carbides and oxides and the final shape of the treated powders. Process parameters such as input power and plasma gas composition allow controlling the degree of powder oxidation and spheroidization of high melting point ceramic powders.

Treatment of refractory powders by a novel, high enthalpy dc plasma

International Nuclear Information System (INIS)

Pershin, L; Mitrasinovic, A; Mostaghimi, J

2013-01-01

Thermophysical properties of CO 2 –CH 4 mixtures at high temperatures are very attractive for materials processing. In comparison with argon, at the same temperature, such a mixture possesses much higher enthalpy and higher thermal conductivity. At high temperatures, CO 2 –CH 4 mixture has a complex composition with strong presence of CO which, in the case of powder treatment, could reduce oxidation. In this work, a dc plasma torch with graphite cathode was used to study the effect of plasma gas composition on spheroidization of tungsten carbide and alumina powders. Two different gas compositions were used to generate the plasma while the torch current was kept at 300 A. Various techniques were employed to assess the average concentration of carbides and oxides and the final shape of the treated powders. Process parameters such as input power and plasma gas composition allow controlling the degree of powder oxidation and spheroidization of high melting point ceramic powders. (paper)

Periodic long-range transport in a large volume dc glow discharge dusty plasma

International Nuclear Information System (INIS)

Thomas, Edward Jr.; Amatucci, William E.; Compton, Christopher; Christy, Brian; Jackson, Jon David

2003-01-01

In an earlier paper, the authors reported on observations of a variety of particle transport phenomena observed in DUPLEX--the DUsty PLasma EXperiment at the Naval Research Laboratory [E. Thomas, Jr., W. E. Amatucci, C. Compton, and B. Christy, Phys. Plasmas 9, 3154 (2002)]. DUPLEX is a large, transparent polycarbonate cylinder that is 40 cm in radius and 80 cm in height. dc glow discharge argon plasmas are generated in DUPLEX. In this paper, the authors expand upon one particular feature of particle transport in DUPLEX, the long-range (i.e., greater than 15 cm), periodic (T∼2.5 min) transport of suspended alumina particles through the plasma. A detailed description of this particle motion through the plasma is presented. Finally, a qualitative model describing the phenomena that lead to this transport is also given

New perspectives on the dynamics of AC and DC plasma arcs exposed to cross-fields

International Nuclear Information System (INIS)

Abdo, Youssef; Rohani, Vandad; Cauneau, François; Fulcheri, Laurent

2017-01-01

Interactions between an arc and external fields are crucially important for the design and the optimization of modern plasma torches. Multiple studies have been conducted to help better understand the behavior of DC and AC current arcs exposed to external and ‘ self-induced ’ magnetic fields, but the theoretical foundations remain very poorly explored. An analytical investigation has therefore been carried out in order to study the general behavior of DC and AC arcs under the effect of random cross-fields. A simple differential equation describing the general behavior of a planar DC or AC arc has been obtained. Several dimensionless numbers that depend primarily on arc and field parameters and the main arc characteristics (temperature, electric field strength) have also been determined. Their magnitude indicates the general tendency pattern of the arc evolution. The analytical results for many case studies have been validated using an MHD numerical model. The main purpose of this investigation was deriving a practical analytical model for the electric arc, rendering possible its stabilization and control, and the enhancement of the plasma torch power. (paper)

New perspectives on the dynamics of AC and DC plasma arcs exposed to cross-fields

Science.gov (United States)

Abdo, Youssef; Rohani, Vandad; Cauneau, François; Fulcheri, Laurent

2017-02-01

Interactions between an arc and external fields are crucially important for the design and the optimization of modern plasma torches. Multiple studies have been conducted to help better understand the behavior of DC and AC current arcs exposed to external and ‘self-induced’ magnetic fields, but the theoretical foundations remain very poorly explored. An analytical investigation has therefore been carried out in order to study the general behavior of DC and AC arcs under the effect of random cross-fields. A simple differential equation describing the general behavior of a planar DC or AC arc has been obtained. Several dimensionless numbers that depend primarily on arc and field parameters and the main arc characteristics (temperature, electric field strength) have also been determined. Their magnitude indicates the general tendency pattern of the arc evolution. The analytical results for many case studies have been validated using an MHD numerical model. The main purpose of this investigation was deriving a practical analytical model for the electric arc, rendering possible its stabilization and control, and the enhancement of the plasma torch power.

Aligned Carbon Nanotubes Array by DC Glow Plasma Etching for Supercapacitor

Directory of Open Access Journals (Sweden)

Yongfeng Luo

2013-01-01

Full Text Available To open the end of carbon nanotubes and make these ends connect with functional carboxyl group, aligned carbon nanotubes (CNTs arrays was etched by DC glow oxygen-argon plasma. With these open-ended carbon nanotubes array as electrode materials to build supercapacitor, we found that the capacity (32.2 F/g increased significantly than that of pure carbon nanotubes (6.7 F/g.

Non-equilibrium nitrogen DC-arc plasma treatment of TiO2 nanopowder.

Science.gov (United States)

Suzuki, Yoshikazu; Gonzalez-Aguilar, José; Traisnel, Noel; Berger, Marie-Hélène; Repoux, Monique; Fulcheri, Laurent

2009-01-01

Non-equilibrium nitrogen DC-arc plasma treatment of a commercial TiO2 anatase nanopowder was examined to obtain nitrogen-doped TiO2. By using a non-thermal discharge at low current (150 mA) and high voltage (1200 V) using pure N2 gas, light yellowish-gray TiO2 powder was successfully obtained within a short period of 5-10 min. XPS and TEM-EELS studies confirmed the existence of doped nitrogen. Due to the relatively mild conditions (plasma power of 180 W), metastable anatase structure and fine crystallite size of TiO2 (ca. 10 nm) were maintained after the plasma treatment. The in-flight powder treatment system used in this study is promising for various type of powder treatment.

Arc Voltage Fluctuation in DC Laminar and Turbulent Plasma Jets Generation

International Nuclear Information System (INIS)

Pan Wenxia; Meng Xian; Wu Chengkang

2006-01-01

Arc voltage fluctuations in a direct current (DC) non-transferred arc plasma generator are experimentally studied, in generating a jet in the laminar, transitional and turbulent regimes. The study is with a view toward elucidating the mechanism of the fluctuations and their relationship with the generating parameters, arc root movement and flow regimes. Results indicate that the existence of a 300 Hz alternating current (AC) component in the power supply ripples does not cause the transition of the laminar plasma jet into a turbulent state. There exists a high frequency fluctuation at 4 kHz in the turbulent jet regime. It may be related to the rapid movement of the anode attachment point of the arc

Deposição por plasma com arco transferido Hardfacing by plasma transfer arc process

Directory of Open Access Journals (Sweden)

Víctor Vergara Díaz

2010-03-01

Full Text Available Em virtude do Processo de Soldagem Plasma com Alimentação de Pó ter similaridades com o Processo de Soldagem Plasma com Alimentação de Arame, foi realizado um estudo comparativo entre ambos os processos utilizando-se a liga a base de cobalto comercialmente conhecida como Stellite 6, como material de adição na forma de pó e arame. A pesquisa foi realizada com a expectativa de ser aplicada nas operações de revestimentos de superfícies, em especial em pás de turbinas hidráulicas desgastadas por cavitação. A seleção do material de adição a ser empregado depende da natureza do mecanismo de desgaste encontrado. No Labsolda, a liga Stellite 6 vem sendo uma das mais utilizadas, por apresentar uma excelente resistência ao desgaste erosivo por cavitação. Foi avaliada a influência da vazão de gás de plasma a partir dos valores de diluição, dimensões do cordão, dureza e microestrutura. O Processo de Soldagem Plasma com Alimentação de Pó foi o que produziu o melhor acabamento superficial, menor diluição, melhor molhamento e maior largura. Com isto abre-se uma nova perspectiva para revestimentos metálicos e neste contexto se insere a recuperação por soldagem de partes erodidas de turbinas hidráulicas.The Plasma powder transferred arc welding process, which uses feed stock in the powder form, has similarities with Plasma wire transferred arc welding. This work describes a comparative study of the two processes using a Cobalt-based alloy commercially known as Stellite 6. This Co-based alloy is recognized for its superior cavitation erosion resistance. The aim of this work is to investigate the potential of PTA coatings for the protection and refurbishiment hydraulic turbine blades. Coatings were evaluated for the influence of Plasma gas flow rate on coating dilution, geometry, hardness and microstructure. Coatings processed with the atomized Stellite 6 powder feestock showed a superior surface quality, lower dilution

Equidensitometry: a method for characterising the structure of plasmas. Qualitative characterisation of the lanthanum d.c. arc by equidensitometry of monochromatic arc photographs

International Nuclear Information System (INIS)

Dittrich, K.; Niebergall, K.; Roessler, H.

1976-01-01

A new method has been developed for the experimental characterization of d.c. arc plasmas. The method consists of the combination of the spectral photography of d.c. arc plasmas with a slitless, stigmatic plane-grating spectrograph and the characterization of the photographs with the aid of photographic equidensitometry. The principles of the method are described. The method is used for the investigation of a lanthanum d.c. arc plasma. The qualitative results of the measurements of the axial distributions of the light emission and lanthanum and calcium particle concentrations in the arc are discussed. The limitations and shortcomings of the method are pointed out. (author)

Desizing of Starch Containing Cotton Fabrics Using Near Atmospheric Pressure, Cold DC Plasma Treatment

Science.gov (United States)

Prasath, A.; Sivaram, S. S.; Vijay Anand, V. D.; Dhandapani, Saravanan

2013-03-01

An attempt has been made to desize the starch containing grey cotton fabrics using the DC plasma with oxygen as the gaseous medium. Process conditions of the plasma reactor were optimized in terms of distance between the plates (3.2 cm), applied voltage (600 V) and applied pressure (0.01 bar) to obtain maximum desizing efficiency. No discolouration was observed in the hot water extracts of the desized sample in presence of iodine though relatively higher solvent extractable impurities (4.53 %) were observed in the plasma desized samples compared to acid desized samples (3.38 %). Also, significant weight loss, improvements in plasma desized samples were observed than that of grey fabrics in terms of drop absorbency.

Dynamic behaviour of dc double anode plasma torch at atmospheric pressure

International Nuclear Information System (INIS)

Tu, X; Cheron, B G; Yan, J H; Cen, K F

2007-01-01

An original dc double anode plasma torch which provides a long-time and highly stable atmospheric plasma jet has been devised for the purpose of hazardous waste treatment. The arc fluctuations and dynamic behaviour of the argon and argon-nitrogen plasma jets under different operating conditions have been investigated by means of classical tools, such as the statistic method, fast Fourier transform (FFT) and correlation analysis. In our experiments, the takeover mode is identified as the fluctuation characteristic of the argon plasma jet while the restrike mode is typical in the argon-nitrogen plasma dynamic behaviour. In the case of pure argon, the FFT and correlation calculation results of electrical signals exhibit the only characteristic frequency of 150 Hz, which originates from the torch power and is independent of any change in the operating conditions. It indicates that the nature of fluctuations in an argon plasma jet is mainly induced by the undulation of the tri-phase rectified power supply. In contrast, besides the same low frequency bulk fluctuation, the dynamic behaviour of the argon-nitrogen plasma jet at high frequency (4.1 kHz) is ascribed to the rapid motion of both arc roots on the anode surface. In addition, it is found that each arc root attachment is rather diffused than located at a fixed position on the anode wall in the argon plasma jet, while constricted arc roots occur when nitrogen is added into argon as the plasma working gas

Self-organization as the cause of different states of dc and hf discharge plasmas

International Nuclear Information System (INIS)

Lozneanu, E.; Dimitriu, D.; Gaman, C.; Furtuna, C.; Filep, E.; Sanduloviciu, M.

2004-01-01

Dc and hf gas discharges used in industrial devices are strongly nonlinear media whose characteristics and behavior critically depend on the type of the device and on the way and the amount of energy injected into the system. Consequently, considering a certain industrial device, it is possible to select, by gradually changing the injected energy, the working regimes that offer the most suitable conditions for a certain practical applications. The consideration of the nonlinear behavior of gaseous conductors (plasmas), created in dc and hf electric fields, and implicitly of the self-organizing phenomena at their origin become important for certain applications (Authors)

Application of Steenbeck's minimum principle for three-dimensional modelling of DC arc plasma torches

International Nuclear Information System (INIS)

Li Heping; Pfender, E; Chen, Xi

2003-01-01

In this paper, physical/mathematical models for the three-dimensional, quasi-steady modelling of the plasma flow and heat transfer inside a non-transferred DC arc plasma torch are described in detail. The Steenbeck's minimum principle (Finkelnburg W and Maecker H 1956 Electric arcs and thermal plasmas Encyclopedia of Physics vol XXII (Berlin: Springer)) is employed to determine the axial position of the anode arc-root at the anode surface. This principle postulates a minimum arc voltage for a given arc current, working gas flow rate, and torch configuration. The modelling results show that the temperature and flow fields inside the DC non-transferred arc plasma torch show significant three-dimensional features. The predicted anode arc-root attachment position and the arc shape by employing Steenbeck's minimum principle are reasonably consistent with experimental observations. The thermal efficiency and the torch power distribution are also calculated in this paper. The results show that the thermal efficiency of the torch always ranges from 30% to 45%, i.e. more than half of the total power input is taken away by the cathode and anode cooling water. The special heat transfer mechanisms at the plasma-anode interface, such as electron condensation, electron enthalpy and radiative heat transfer from the bulk plasma to the anode inner surface, are taken into account in this paper. The calculated results show that besides convective heat transfer, the contributions of electron condensation, electron enthalpy and radiation to the anode heat transfer are also important (∼30% for parameter range of interest in this paper). Additional effects, such as the non-local thermodynamic equilibrium plasma state near the electrodes, the transient phenomena, etc, need to be considered in future physical/mathematical models, including corresponding measurements

Current transfer in dc non-transferred arc plasma torches

International Nuclear Information System (INIS)

Ghorui, S; Sahasrabudhe, S N; Das, A K

2010-01-01

Fundamentals of current transfer to the anodes in dc non-transferred arc plasma torches are investigated. Specially designed anodes made of three mutually isolated sections and external dc axial magnetic fields of various strengths are utilized to explore the conditions for different diffused and constricted attachments of the arc with the anode. A number of new facts are revealed in the exercise. Under constricted attachment, formation of arc root takes place. Spontaneous and magnetically induced movements of the arc root, their dependence on the arc current and the strength of the external magnetic field, most probable arc root velocity, variation of the root velocity with strength of the applied magnetic field, the effect of swirl on the rotational speed of the arc root are some of the important features investigated. Two new techniques are introduced: one for measurement of the arc root diameter and the other for determination of the negative electric field in the boundary layer over the anode. While the first one exploits the rigid column behaviour of the arcs, the second one utilizes the shooting back of the residual electrons over an arc spot. Sample calculations are provided.

Megawatt low-temperature DC plasma generator with divergent channels of gas-discharge tract

Science.gov (United States)

Gadzhiev, M. Kh.; Isakaev, E. Kh.; Tyuftyaev, A. S.; Yusupov, D. I.; Sargsyan, M. A.

2017-04-01

We have developed and studied a new effective megawatt double-unit generator of low-temperature argon plasma, which belongs to the class of dc plasmatrons and comprises the cathode and anode units with divergent gas-discharge channels. The generator has an efficiency of about 80-85% and ensures a long working life at operating currents up to 4000 A.

Antimicrobial properties of uncapped silver nanoparticles synthesized by DC arc thermal plasma technique.

Science.gov (United States)

Shinde, Manish; Patil, Rajendra; Karmakar, Soumen; Bhoraskar, Sudha; Rane, Sunit; Gade, Wasudev; Amalnerkar, Dinesh

2012-02-01

We, herein, report the antimicrobial properties of uncapped silver nanoparticles for a Gram positive model organism, Bacillus subtilis. Uncapped silver nanoparticles have been prepared using less-explored DC arc thermal plasma technique by considering its large scale generation capability. It is observed that the resultant nanoparticles show size as well as optical property dependent antimicrobial effect.

Development of the DC-RF Hybrid Plasma Source and the Application to the Etching and Texturing of the Silicon Surface

International Nuclear Information System (INIS)

Kim, Ji Hun

2011-02-01

Plasma used in dry etching, thin film deposition and surface treatment for display or semiconductor industries are operating at low pressures in general. However, low pressure processing is very costly due to the use of vacuum equipment and vacuum components. Subsequent wet processing is environmentally undesirable due to the use of a large amount of chemicals. Also, the usage of vacuum processing increases fabrication cost and decreases productivity. If stable atmospheric plasmas can be used, not only the decrease in processing costs but also the increase in productivity could be obtained. New DC arc plasmatron with a hot rod cathode and cold nozzle anode was developed and its V-A (Volt-Ampere) characteristics were investigated. Outlook of the measured V-A characteristics cleared the question of the stability of arc burning in the new DC arc plasmatron. The plasmatron that has a stable operations with distributed anode spot could possibly be applied to plasma chemical processing. And measured value of the erosion rate for copper anode is m Cu 3.6x10 -10 g/C which is better than corresponding data for thermo-ionic emission cathodes made of tungsten mw ∼10 -9 g/C. These facts mean that plasmatron durability reaches ∼10 3 h. The low anode erosion rate is related to the large surface of arc-anode contact due to distributed anode arc spot, which reduces the current density. Unique characteristics of the new plasma source concerning its durability and plasma purity at rather low temperatures make it an interesting tool for technical applications, such as etching/deposition and chemical reaction. To apply a plasma processing, the T-type plasmatron was modified to A-type. The A-type plasmatron was used to activate the CF 4 and SF 6 gases in etching experiments at atmospheric and low pressure. To reduce the recombination rate of the activated gas particles inside a plasmatron and let them preserve their activated state outside, the whole device was installed outside of

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

International Nuclear Information System (INIS)

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

2014-01-01

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

Synthesis of ZnO nanopowders by DC thermal plasma for dye-sensitized solar cells

Energy Technology Data Exchange (ETDEWEB)

Lee, Soo-Jung; Choi, Jinsub [Department of Chemical Engineering, Inha University, 253 Yonghyun-dong, Nam-gu, Incheon 402-751 (Korea, Republic of); Park, Dong-Wha, E-mail: dwpark@inha.ac.kr [Department of Chemical Engineering, Inha University, 253 Yonghyun-dong, Nam-gu, Incheon 402-751 (Korea, Republic of)

2013-05-01

Highlights: ► ZnO nanopowders were synthesized using DC thermal plasma process. ► Type and flow rate of reaction gas were controlled as experimental variables. ► Various morphologies were identified by changing the reaction gas. ► The photovoltaic performances were promoted by removing the unreacted precursors. ► DSSCs based on 1D nanostructure ZnO show the enhanced energy conversion efficiency. -- Abstract: Zinc oxide (ZnO) nanopowders were synthesized from commercially available micro-sized zinc powders (Aldrich Co., 98%, 10 μm) by a DC thermal plasma process at atmospheric pressure. The micro-sized zinc powders were vaporized in the plasma region, after which the plasma processing equipment was rapidly quenched, resulting in the formation of ZnO nanopowders with a size of less than 300 nm. Two different reaction gases of oxygen and carbon dioxide were used as the oxygen source and each gas flow rate was controlled as a process variable. The obtained ZnO nanopowders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). All synthesized ZnO nanopowders showed high crystalline wurtzite structures and the differences in their morphologies were strongly dependent on the operating variables. The photocurrent–voltage (J–V) curve of the ZnO nanopowders with a dye of ruthenium (II) 535 bis-TBA (N719, Solaronix) in redox electrolyte showed an overall energy conversion efficiency (η) of 2.54%, demonstrating that the application of the mass-producible ZnO nanopowders by thermal plasma processing to DSSC was feasible.

Optical characterization of single-crystal diamond grown by DC arc plasma jet CVD

Science.gov (United States)

Hei, Li-fu; Zhao, Yun; Wei, Jun-jun; Liu, Jin-long; Li, Cheng-ming; Lü, Fan-xiu

2017-12-01

Optical centers of single-crystal diamond grown by DC arc plasma jet chemical vapor deposition (CVD) were examined using a low-temperature photoluminescence (PL) technique. The results show that most of the nitrogen-vacancy (NV) complexes are present as NV- centers, although some H2 and H3 centers and B-aggregates are also present in the single-crystal diamond because of nitrogen aggregation resulting from high N2 incorporation and the high mobility of vacancies under growth temperatures of 950-1000°C. Furthermore, emissions of radiation-induced defects were also detected at 389, 467.5, 550, and 588.6 nm in the PL spectra. The reason for the formation of these radiation-induced defects is not clear. Although a Ni-based alloy was used during the diamond growth, Ni-related emissions were not detected in the PL spectra. In addition, the silicon-vacancy (Si-V)-related emission line at 737 nm, which has been observed in the spectra of many previously reported microwave plasma chemical vapor deposition (MPCVD) synthetic diamonds, was absent in the PL spectra of the single-crystal diamond prepared in this work. The high density of NV- centers, along with the absence of Ni-related defects and Si-V centers, makes the single-crystal diamond grown by DC arc plasma jet CVD a promising material for applications in quantum computing.

Investigation of Dusts Effect and Negative Ion in DC Plasmas by Electric Probes

Science.gov (United States)

Oh, Hye Taek; Kang, Inje; Bae, Min-Keun; Park, Insun; Lee, Seunghwa; Jeong, Seojin; Chung, Kyu-Sun

2017-10-01

Dust is typically negatively charged by electron attachment whose thermal velocities are fast compared to that of the heavier ions. The negatively charged particles can play a role of negative ions which affect the quasi-neutrality of background plasma. To investigate effect of metal dusts and negative ion on plasma and materials, metal dusts are injected into background Ar plasma which is generated by tungsten filament using dust dispenser on Cubical Plasma Device (CPD). The CPD has following conditions: size =24x24x24cm3, plasma source =DC filament plasma (ne 1x10x1010, Te 2eV), background gas =Ar, dusts =tungsten powder (diameter 1.89micron). The dust dispenser is developed to quantitate of metal dust by ultrasonic transducer. Electronegative plasmas are generated by adding O2 + Ar plasma to compare negative ion and dust effect. A few grams of micron-sized dusts are placed in the dust dispenser which is located at the upper side of the Cubical Plasma Device. The falling particles by dust dispenser are mainly charged up by the collection of the background plasma. The change in parameters due to negative ion production are characterized by measuring the floating and plasma potential, electron temperature and negative ion density using electric probes.

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

Energy Technology Data Exchange (ETDEWEB)

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

2011-12-30

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

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

International Nuclear Information System (INIS)

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

2014-01-01

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

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

Science.gov (United States)

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

2017-10-01

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

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

International Nuclear Information System (INIS)

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

2017-01-01

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

Effects of applied dc radial electric fields on particle transport in a bumpy torus plasma

Science.gov (United States)

Roth, J. R.

1978-01-01

The influence of applied dc radial electric fields on particle transport in a bumpy torus plasma is studied. The plasma, magnetic field, and ion heating mechanism are operated in steady state. Ion kinetic temperature is more than a factor of ten higher than electron temperature. The electric fields raise the ions to energies on the order of kilovolts and then point radially inward or outward. Plasma number density profiles are flat or triangular across the plasma diameter. It is suggested that the radial transport processes are nondiffusional and dominated by strong radial electric fields. These characteristics are caused by the absence of a second derivative in the density profile and the flat electron temperature profiles. If the electric field acting on the minor radius of the toroidal plasma points inward, plasma number density and confinement time are increased.

Properties and etching rates of negative ions in inductively coupled plasmas and dc discharges produced in Ar/SF6

International Nuclear Information System (INIS)

Draghici, M.; Stamate, E.

2010-01-01

Negative ion production is investigated in a chamber with transversal magnetic filter operated in dc or inductively coupled plasma (ICP) modes in Ar/SF 6 gas mixtures. Plasma parameters are evaluated by mass spectrometry and Langmuir probe for different discharge conditions. The density ratio of negative ion to electron exceeded 300 in dc mode while it was below 100 in the ICP mode. The possibility to apply a large positive bias to an electrode without affecting the plasma potential and the transition from a negative sheath to anodic glow are also investigated. The etching rates by positive and negative ions are evaluated on silicon substrate for different Ar/SF 6 gas ratios. The etching rate by negative ions was with less than 5% smaller than that by positive ions.

Properties and etching rates of negative ions in inductively coupled plasmas and dc discharges produced in Ar/SF6

DEFF Research Database (Denmark)

Draghici, Mihai; Stamate, Eugen

2010-01-01

of negative ion to electron exceeded 300 in dc mode while it was below 100 in the ICP mode. The possibility to apply a large positive bias to an electrode without affecting the plasma potential and the transition from a negative sheath to anodic glow are also investigated. The etching rates by positive...... and negative ions are evaluated on silicon substrate for different Ar/SF6 gas ratios. The etching rate by negative ions was with less than 5% smaller than that by positive ions.......Negative ion production is investigated in a chamber with transversal magnetic filter operated in dc or inductively coupled plasma (ICP) modes in Ar/SF6 gas mixtures. Plasma parameters are evaluated by mass spectrometry and Langmuir probe for different discharge conditions. The density ratio...

The determination of the electron collision cross sections for the momentum transfer in potassium by measuring the DC conductivity of a plasma

International Nuclear Information System (INIS)

Luknarova, M.; Veis, S.

1976-01-01

The DC conductivity of a thermally produced plasma in a plasma diode has been measured in pure potassium vapour. The plasma diode consists of two tungsten electrodes heated to a temperature of 2200 K. A simple theory for determining the influence of the plasma sheaths on the measured conductivity was developed and experimental conditions were established under which the potential drops across the sheaths could be neglected. By measuring the DC conductivity of the plasma at temperatures ranging from 1250 to 1600 K the potassium momentum-transfer cross section has been obtained. The measured cross section (2.37 +- 0.24) x 10 -14 cm 2 at 1500 K is in good agreement with results of other workers. Results for the work function of tungsten in potassium vapour were also obtained. (author)

Influence of a transverse magnetic field on arc root movements in a dc plasma torch: Diamagnetic effect of arc column

International Nuclear Information System (INIS)

Kim, Keun Su

2009-01-01

The effect of a transverse magnetic field on the anodic arc root movement inside a dc plasma torch has been investigated. The arc voltage fluctuation, which represents the degree of the arc instability, was reduced to 28.6% of the original value and the high frequency components in the voltage signal also decreased in their magnitudes. The inherent arc instability in a dc thermal plasma torch seems to be suppressed by a diamagnetic effect of the arc column. Furthermore, the measured voltage wave forms indicated that the arc root attachment mode would be controllable by a transverse magnetic field

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

Energy Technology Data Exchange (ETDEWEB)

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

2014-12-15

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

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

International Nuclear Information System (INIS)

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

2006-01-01

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

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

Science.gov (United States)

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

2018-03-01

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

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

Science.gov (United States)

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

2018-03-01

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

Characterization of a Fabry--Perot interferometer and a dc arc plasma jet for spectrochemical analysis

Energy Technology Data Exchange (ETDEWEB)

Ford, C.S.

1979-01-01

A system involving the use of a Fabry--Perot interferometer in combination with a dc arc plasma jet has been constructed and characterized for spectrochemical analysis. Parameters such as flow rate ratio, observation region, electrode composition and orifice size have been considered. Improvements such as noise reduction and dry aerosol introduction of samples were suggested.

Characterization of a Fabry--Perot interferometer and a dc arc plasma jet for spectrochemical analysis

International Nuclear Information System (INIS)

Ford, C.S.

1979-01-01

A system involving the use of a Fabry--Perot interferometer in combination with a dc arc plasma jet has been constructed and characterized for spectrochemical analysis. Parameters such as flow rate ratio, observation region, electrode composition and orifice size have been considered. Improvements such as noise reduction and dry aerosol introduction of samples were suggested

Synthesis of few-layer graphene on a Ni substrate by using DC plasma enhanced chemical vapor deposition (PE-CVD)

International Nuclear Information System (INIS)

Kim, Jeong Hyuk; Castro, Edward Joseph; Hwang, Yong Gyoo; Lee, Choong Hun

2011-01-01

In this work, few-layer graphene (FLG) was successfully grown on polycrystalline Ni a large scale by using DC plasma enhanced chemical vapor deposition (DC PE-CVD), which may serve as an alternative route in large-scale graphene synthesis. The synthesis time had an effect on the quality of the graphene produced. The applied DC voltage, on the other hand, influenced the minimization of the defect densities in the graphene grown. We also present a method of producing a free-standing polymethyl methacrylate (PMMA)/graphene membrane on a FeCl 3(aq) solution, which could then be transferred to the desired substrate.

Comparative Observation of Ar, Ar-H2 and Ar-N2 DC Arc Plasma Jets and Their Arc Root Behaviour at Reduced Pressure

International Nuclear Information System (INIS)

Pan Wenxia; Meng Xian; Li Teng; Chen Xi; Wu Chengkang

2007-01-01

Results observed experimentally are presented, about the DC arc plasma jets and their arc-root behaviour generated at reduced gas pressure without or with an applied magnetic field. Pure argon, argon-hydrogen or argon-nitrogen mixture was used as the plasma-forming gas. A specially designed copper mirror was used for a better observation of the arc-root behaviour on the anode surface of the DC non-transferred arc plasma torch. It was found that in the cases without an applied magnetic field, the laminar plasma jets were stable and approximately axisymmetrical. The arc-root attachment on the anode surface was completely diffusive when argon was used as the plasma-forming gas, while the arc-root attachment often became constrictive when hydrogen or nitrogen was added into the argon. As an external magnetic field was applied, the arc root tended to rotate along the anode surface of the non-transferred arc plasma torch

Influence of DC plasma modification on the selected properties and the geometrical surface structure of polylactide prior to autocatalytic metallization

Energy Technology Data Exchange (ETDEWEB)

Moraczewski, Krzysztof, E-mail: kmm@ukw.edu.pl [Kazimierz Wielki University, Chodkiewicza 30, 85-064 Bydgoszcz (Poland); Rytlewski, Piotr [Kazimierz Wielki University, Chodkiewicza 30, 85-064 Bydgoszcz (Poland); Malinowski, Rafał [Institute for Engineering of Polymer Materials and Dyes, Marii Skłodowskiej-Curie 55, 87-100 Toruń (Poland); Tracz, Adam [Centre for Molecular and Macromolecular Studies of the Polish Academy of Sciences, Sienkiewicza 112, 90-363 Łódź (Poland); Żenkiewicz, Marian [Institute for Engineering of Polymer Materials and Dyes, Marii Skłodowskiej-Curie 55, 87-100 Toruń (Poland)

2015-03-01

The paper presents the results of studies to determine the applicability of plasma modification in the process of polylactide (PLA) surface preparation prior to the autocatalytic metallization. The polylactide plasma modification was carried out in an oxygen or nitrogen chemistry. The samples were tested with the following methods: scanning electron microscopy (SEM), atomic force microscopy (AFM), goniometry and electron spectrophotometry (XPS). Scanning electron microscopy and atomic force microscopy images were demonstrated. The results of surface free energy calculations, performed based on the results of the contact angle measurements have been presented. The results of the qualitative (degree of oxidation or nitridation) and quantitative analysis of the chemical composition of the polylactide surface layer have also been described. The results of the studies show that the DC plasma modification performed in the proposed condition is a suitable as a method of surface preparation for the polylactide metallization. - Highlights: • We modified polylactide surface layer with plasma generated in oxygen or nitrogen. • We tested selected properties and surface structure of modified samples. • DC plasma modification can be used to prepare the PLA surface for metallization. • For better results metallization should be preceded by sonication process.

Resonant mode for a dc plasma spray torch by means of pressure–voltage coupling: application to synchronized liquid injection

International Nuclear Information System (INIS)

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

2013-01-01

Electric arc instabilities in dc plasma torches result in non-homogeneous treatment of nanosized solid particles injected into the plasma jets. In the particular case of suspension plasma spraying, large discrepancies in the particles trajectories and thermal histories make the control of coating properties more difficult to achieve. In this paper, a new approach of arc dynamics highlights the existence of different resonant modes and the possibility of their coupling. This study leads us to design a special plasma torch working in a very regular pulsed regime. Then, an innovative injection system based on the drop-on-demand method synchronized with the plasma oscillations is presented as an efficient method to control the dynamics of plasma/particles interactions. (paper)

Parameters of the plasma of a dc pulsating discharge in a supersonic air flow

Energy Technology Data Exchange (ETDEWEB)

Shibkov, V. M., E-mail: shibkov@phys.msu.ru; Shibkova, L. V.; Logunov, A. A. [Moscow State University, Faculty of Physics (Russian Federation)

2017-03-15

A dc discharge in a cold (T = 200 K) supersonic air flow at a static pressure of 200–400 Torr was studied experimentally. The excited unsteady pulsating discharge has the form of a thin plasma channel with a diameter of ≤1 mm, stretched downstream the flow. Depending on the discharge current, the pulsation frequency varies from 800 to 1600 Hz and the electron temperature varies from 8000 to 15000 K.

The influence of ethanol addition on the spatial emission distribution of traces in a vertical argon stabilized DC arc plasma

Directory of Open Access Journals (Sweden)

MARIJA TODOROVIC

2004-05-01

Full Text Available The plasma of a vertical argon stabilized DC arc at atmospheric pressure is applied as a spectrochemical source. The lateral distributions of relative spectral line intensities of some trace elements (Zn, Pt, Cd, Mg, Ca and Al introduced into the plasma in the form of aqueous and ethanol–aqueous solutions were experimentally determined. These distributions were correlated with the calculated equilibrium plasma composition of the arc plasma. On the basis of the obtained results, an explanation of the influence of ethanol addition on the radiation densities from an arc plasma is given.

Study on effect of plasma surface treatments for diamond deposition by DC arc plasmatron.

Science.gov (United States)

Kang, In-Je; Joa, Sang-Beom; Lee, Heon-Ju

2013-11-01

To improve the thermal conductivity and wear resistance of ceramic materials in the field of renewable energy technologies, diamond coating by plasma processing has been carried out in recent years. This study's goal is to improve diamond deposition on Al2O3 ceramic substrates by plasma surface treatments. Before diamond deposition was carried out in a vacuum, plasma surface treatments using Ar gas were conducted to improve conditions for deposition. We also conducted plasma processing for diamond deposition on Al2O3 ceramic substrates using a DC arc Plasmatron. The Al2O3 ceramic substrates with diamond film (5 x 15 mm2), were investigated by SEM (Scanning Electron Microscopy), AFM (Atomic Force Microscopy) and XRD (X-ray Diffractometer). Then, the C-H stretching of synthetic diamond films by FTIR (Fourier Transform Infrared Spectroscopy) was studied. We identified nanocrystalline diamond films on the Al2O3 ceramic substrates. The results showed us that the deposition rate of diamond films was 2.3 microm/h after plasma surface treatments. Comparing the above result with untreated ceramic substrates, the deposition rate improved with the surface roughness of the deposited diamond films.

Etching Effect of an Atmospheric DC Arc Plasmatron

International Nuclear Information System (INIS)

Chun, Se Min; Kim, Ji Hun; Kang, In Je; Lee, Heon Ju

2010-01-01

Thermal plasmas (especially arc plasma) were extensively industrialized, principally by aeronautic sector. Cold plasma technologies have been developed in the microelectronics but their vacuum equipment limits their implantation. Plasmas used in dry etching, thin film deposition and surface treatment for display or semiconductor industries are operating at low pressures in very costly due to the use of vacuum equipment and vacuum components. Use of DC arc plasmatrons in welding, soldering, and cutting of metals is well known. A DC-arc plasmatron with high durability was reported to be a suitable device for etching silicon and photo-resist surfaces

Studies of internal stress in diamond films prepared by DC plasma chemical vapour deposition

International Nuclear Information System (INIS)

Wang Wanlu; Gao Jinying; Liao Kejun; Liu Anmin

1992-01-01

The internal stress in diamond thin films deposited by DC plasma CVD was studied as a function of methane concentration and deposited temperature. Experimental results have shown that total stress in diamond thin films is sensitive to the deposition conditions. The results also indicate that the compressive stress can be explained in terms of amorphous state carbon and hydrogen, and tensile stress is ascribed to the grain boundary relaxation model due to high internal surface area and microstructure with voids

Structural evolution of Ti destroyable interlayer in large-size diamond film deposition by DC arc plasma jet

Science.gov (United States)

Guo, Jianchao; Li, Chengming; Liu, Jinlong; Wei, Junjun; Chen, Liangxian; Hua, Chenyi; Yan, Xiongbo

2016-05-01

The addition of titanium (Ti) interlayer was verified to reduce the residual stress of diamond films by self-fracturing and facilitate the harvest of a crack-free free-standing diamond film prepared by direct current (DC) arc plasma jet. In this study, the evolution of the Ti interlayer between large-area diamond film and substrate was studied and modeled in detail. The evolution of the interlayer was found to be relevant to the distribution of the DC arc plasma, which can be divided into three areas (arc center, arc main, and arc edge). The formation rate of titanium carbide (TiC) in the arc main was faster than in the other two areas and resulted in the preferred generation of crack in the diamond film in the arc main during cooling. Sandwich structures were formed along with the growth of TiC until the complete transformation of the Ti interlayer. The interlayer released stress via self-fracture. Avoiding uneven fragile regions that formed locally in the interlayer and achieving cooperatively released stress are crucial for the preparation of large crack-free diamond films.

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

Science.gov (United States)

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

2017-10-01

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

Analysis of plasma protein adsorption onto DC-Chol-DOPE cationic liposomes by HPLC-CHIP coupled to a Q-TOF mass spectrometer

KAUST Repository

Capriotti, Anna Laura; Caracciolo, Giulio; Caruso, Giuseppe; Cavaliere, Chiara; Pozzi, Daniela; Samperi, Roberto; Laganà , Aldo

2010-01-01

Plasma protein adsorption is regarded as a key factor in the in vivo organ distribution of intravenously administered drug carriers, and strongly depends on vector surface characteristics. The present study aimed to characterize the "protein corona" absorbed onto DC-Chol-DOPE cationic liposomes. This system was chosen because it is one of the most efficient and widely used non-viral formulations in vitro and a potential candidate for in vivo transfection of genetic material. After incubation of human plasma with cationic liposomes, nanoparticle-protein complex was separated from plasma by centrifugation. An integrated approach based on protein separation by one-dimensional 12% polyacrylamide gel electrophoresis followed by the automated HPLC-Chip technology coupled to a high-resolution mass spectrometer was employed for protein corona characterization. Thirty gel lanes, approximately 2 mm, were cut, digested and analyzed by HPLC-MS/MS. Fifty-eight human plasma proteins adsorbed onto DC-Chol-DOPE cationic liposomes were identified. The knowledge of the interactions of proteins with liposomes can be exploited for future controlled design of colloidal drug carriers and possibly in the controlled creation of biocompatible surfaces of other devices that come into contact with proteins in body fluids. © 2010 Springer-Verlag.

Analysis of plasma protein adsorption onto DC-Chol-DOPE cationic liposomes by HPLC-CHIP coupled to a Q-TOF mass spectrometer

KAUST Repository

Capriotti, Anna Laura

2010-09-22

Plasma protein adsorption is regarded as a key factor in the in vivo organ distribution of intravenously administered drug carriers, and strongly depends on vector surface characteristics. The present study aimed to characterize the "protein corona" absorbed onto DC-Chol-DOPE cationic liposomes. This system was chosen because it is one of the most efficient and widely used non-viral formulations in vitro and a potential candidate for in vivo transfection of genetic material. After incubation of human plasma with cationic liposomes, nanoparticle-protein complex was separated from plasma by centrifugation. An integrated approach based on protein separation by one-dimensional 12% polyacrylamide gel electrophoresis followed by the automated HPLC-Chip technology coupled to a high-resolution mass spectrometer was employed for protein corona characterization. Thirty gel lanes, approximately 2 mm, were cut, digested and analyzed by HPLC-MS/MS. Fifty-eight human plasma proteins adsorbed onto DC-Chol-DOPE cationic liposomes were identified. The knowledge of the interactions of proteins with liposomes can be exploited for future controlled design of colloidal drug carriers and possibly in the controlled creation of biocompatible surfaces of other devices that come into contact with proteins in body fluids. © 2010 Springer-Verlag.

Pulsed-wave tissue Doppler imaging of the myocardium of cats with induced thyrotoxicosis Doppler tecidual pulsado do miocárdio de gatos com tirotoxicose induzida

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Daniel Capucho de Oliveira

2011-06-01

Full Text Available Left ventricular myocardial motion was quantified using pulsed-wave tissue Doppler imaging (PW-TDI in nine adult cats before and after thyrotoxicosis induction. In order to induce thyrotoxicosis, all cats were given 150µg kg-1 of levothyroxine sodium as a single oral dose each day for 10 weeks. PW-TDI examinations were performed immediately before the induction and by the end of the experimental protocol. An increase in myocardial motion velocity was documented at the interventricular septum level, demonstrated by an elevation in systolic (Sa, and early (Ea and late (Aa diastolic waves (PA velocidade de movimentação miocárdica do ventrículo esquerdo foi quantificada por meio de exames ecocardiográficos com Doppler tecidual pulsado (PW-TDI em nove gatos adultos antes e após indução à tirotoxicose. Para indução da tirotoxicose, todos os gatos receberam doses diárias de 150mg kg-1 de levotiroxina sódica, por via oral, durante 10 semanas. Os exames de PW-TDI foram realizados imediatamente antes da indução e ao final do protocolo experimental. Uma elevação na velocidade de movimentação miocárdica foi documentada ao nível do septo interventricular, demonstrado por um aumento das ondas sistólica (Sa e diastólicas (Ea e Aa; P<0,05. No entanto, nenhuma alteração nos valores de Sa, Ea e Aa foi encontrada ao nível da parede livre do ventrículo esquerdo. A frequência cardíaca aumentou significativamente entre os momentos experimentais, sendo que três animais apresentaram fusão das ondas Aa e Ea ao final do experimento. O protocolo experimental utilizado neste estudo causou alterações na velocidade de movimentação do miocárdio ventricular esquerdo, mas sem causar danos à função diastólica do ventrículo esquerdo.

Development of solid oxide fuel cells by applying DC and RF plasma deposition technologies

Energy Technology Data Exchange (ETDEWEB)

Schiller, G.; Henne, R.; Lang, M.; Mueller, M. [Deutsches Zentrum fuer Luft- und Raumfahrt (DLR), Institut fuer Technische Thermodynamik, Postfach 800370, 70503 Stuttgart (Germany)

2004-04-01

Based on advanced plasma deposition technology with both DC and RF plasmas DLR Stuttgart has developed a concept of a planar SOFC with consecutive deposition of all layers of a thin-film cell onto a porous metallic substrate support. This concept is an alternative approach to conventionally used sintering techniques for SOFC fabrication without needing any sintering steps or other thermal post-treatment. Furthermore, is has the potential to be developed into an automated continous production process. For both stationary and mobile applications, adequate stack designs and stack technologies have been developed. Future development work will focus on light-weight stacks to be applied as an Auxillary Power Unit (APU) for on-board electricity supply in passenger cars and airplanes. This paper describes the plasma deposition technologies used for cell fabrication and the DLR spray concept including the resulting stack designs. The current status of development and recent progress with respect to materials development and electrochemical characterization of single cells and short-stacks is presented. (Abstract Copyright [2004], Wiley Periodicals, Inc.)

Analysis of the neutral drag force in a dc glow discharge dusty plasma

International Nuclear Information System (INIS)

Thomas, Edward Jr.; Williams, Jeremiah

2005-01-01

In this paper, the authors report on a series of experiments that use carefully applied perturbations to a dust cloud to reproducibly investigate the formation of the microparticle cloud and the formation of dust cloud-plasma interface. Here, one micron diameter alumina microparticles are suspended in an argon dc glow discharge plasma. A perturbing voltage pulse is applied to the cathode, causing a momentary disruption in the confinement of the dust cloud. After the perturbation, the cloud reforms, typically with a central 'mass' and two 'streams' of particles that are flowing into the cloud from both sides. Through the use of stereoscopic particle image velocimetry (stereo-PIV), the complete three-dimensional velocity of the microparticles can be measured. The particles in the streams are used as test particles to characterize the forces acting upon the microparticles. Analysis of the experimental measurements suggests that the effective neutral drag force may be lower than expected

Ultra-som pulsado de baixa intensidade em fraturas diafisárias: aplicação clínica em cães Low-intensity pulsed ultrasound in diaphyseal fractures: clinical application in dogs

Directory of Open Access Journals (Sweden)

Valéria Lima de Sousa

2008-08-01

Full Text Available Os efeitos da estimulação ultra-sônica sobre a consolidação óssea têm sido demonstrados por trabalhos experimentais e clínicos. Este estudo teve por objetivo investigar a aplicação clínica do ultra-som pulsado de baixa intensidade como tratamento adjuvante de fraturas diafisárias em cães. Foram utilizados 16 cães de raças variadas, com faixa etária entre sete meses e seis anos, peso corpóreo entre 2,5 e 43kg, portadores de fraturas diafisárias fechadas recentes localizadas no rádio e ulna, fêmur ou tíbia e fíbula, estabilizadas por procedimentos de osteossíntese (fixação esquelética externa, pinos intramedulares ou a associação desses métodos. Os cães foram divididos em dois grupos: fraturas estabilizadas tratadas por ultra-som de baixa intensidade (grupo tratado, n=8; fraturas estabilizadas, não tratadas por estimulação ultra-sônica, (grupo controle, n=8. Os animais foram avaliados por exames clínicos e radiográficos nos períodos pré-operatório, pós-operatório imediato e a cada 30 dias posteriores aos procedimentos cirúrgicos. Realizou-se tratamento com ultra-som pulsado (sinal senoidal com freqüência de 1,5MHz, largura de pulso de 200µs e freqüência de repetição de 1kHz de baixa intensidade (30mW cm-2, aplicado de modo estacionário no foco de fratura. A terapia ultra-sônica foi realizada 20 minutos por dia, durante 21 dias consecutivos, a partir do período compreendido entre o 1° e o 9° dia pós-operatório. O teste t de Student, empregado na análise estatística, mostrou diferença significante (PThe effects of ultrasound stimulation on bone healing have been demonstrated in experimental and clinical studies. The purpose of this study was to investigate the clinical application of low-intensity pulsed ultrasound as an adjuvant for the treatment of diaphyseal fractures in dogs. Sixteen dogs of different breeds, ages ranging from seven months to six years, weighing from 2.5 to 43kg, were

Effect of DC Plasma Electrolytic Oxidation on Surface Characteristics and Corrosion Resistance of Zirconium

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Maciej Sowa

2018-05-01

Full Text Available Zr is a valve metal, the biocompatibility of which is at least on par with Ti. Recently, numerous attempts of the formation of bioactive coatings on Zr by plasma electrolytic oxidation (PEO in solutions that were based on calcium acetate and calcium β-glycerophosphate were made. In this study, the direct current (DC PEO of commercially pure zirconium in the solutions that contained Ca(H2PO22, Ca(HCOO2, and Mg(CH3COO2 was investigated. The treatment was conducted at 75 mA/cm2 up to 200, 300, or 400 V. Five process stages were discerned. The treatment at higher voltages resulted in the formation of oxide layers that had Ca/P or (Mg+Ca/P ratios that were close to that of hydroxyapatite (Ca/P = 1.67, determined by SEM/EDX. The corrosion resistance studies were performed using electrochemical impedance spectroscopy (EIS and DC polarization methods. R(Q[R(QR] circuit model was used to fit the EIS data. In general, the coatings that were obtained at 200 V were the most corrosion resistant, however, they lacked the porous structure, which is typical for PEO coatings, and is sought after in the biomedical applications. The treatment at 400 V resulted in the formation of the coatings that were more corrosion resistant than those that were obtained at 300 V. This was determined mainly by the prevailing plasma regime at the given process voltage. The pitting resistance of Zr was also improved by the treatment, regardless of the applied process conditions.

Generation mechanism of hydrogen peroxide in dc plasma with a liquid electrode

Science.gov (United States)

Takeuchi, Nozomi; Ishibashi, Naoto

2018-04-01

The production mechanism of liquid-phase H2O2 in dc driven plasma in O2 and Ar with a water electrode was investigated. When a water anode was used, the concentration of H2O2 increased linearly with the treatment time. The production rate was proportional to the discharge current, and there was no dependence on the gap distance. On the other hand, the production rate was much smaller with a water anode. We concluded that the production of gas-phase H2O2 in the cathode sheath just above a water cathode and diffusion of this H2O2 into the water constitute the key mechanism in the production of liquid-phase H2O2.

Pulsed dc self-sustained magnetron sputtering

International Nuclear Information System (INIS)

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

2008-01-01

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

Dc to ac field conversion due to leaky-wave excitation in a plasma slab behind an ionization front

International Nuclear Information System (INIS)

Kostin, V A; Vvedenskii, N V

2015-01-01

We present a way for generating coherent tunable electromagnetic radiation through dc to ac field conversion by an ionization front. The conversion is caused by the excitation of leaky waves behind the transversely limited ionization front propagating in a uniform electrostatic field. This differs significantly from the well-known dc-to-ac-radiation-converter models which consider Doppler-like frequency conversion by a transversely unlimited ionization front propagating in a spatially periodic electric field. We explore the dispersion properties and excitation of these leaky waves radiated through the transverse plasma boundary at the Cherenkov angle to the direction of propagation of a superluminal ionization front as dependent on the parameters of the plasma produced and on the speed of the ionization front. It is shown that not only the center frequency but also the duration and waveform of the generated pulse may significantly depend on the speed of the ionization front. The results indicate the possibility of using such converters based on planar photoconductive antennas to create sources of microwave and terahertz radiation with controllable waveforms that are transformed from video to radio pulse when the angle of incident ionizing radiation is tuned. (paper)

Formation of Ti-N graded bioceramic layer by DC hollow-cathode plasma nitriding

Institute of Scientific and Technical Information of China (English)

ZHENG Chuan-lin

2004-01-01

Ti-N graded ceramic layer was formed on titanium by using DC hollow-cathode plasma nitriding technique. The structure of Ti-N layer was analyzed using X-ray diffractometry(XRD) with Cu Kα radiation, and the microhardness( HV0.1) was measured from the surface to inner along the cross section of Ti-N layer. The results indicate that the Ti-N graded layer is composed of ε-Ti2 N, δ-TiN and α-Ti(N) phases. Mechanism discussion shows that hollow-cathode discharge can intensify gas ionization, increase current density and enhance the nitriding potential, which directly increases the thickness of the diffusion coatings compared with traditional nitriding methods.

DESGASTE POR ABRASIÓN DEL ACERO API 5L X65 REVESTIDO CON NIOBIO POR ASPERSIÓN TÉRMICA A PLASMA Y CON INCONEL 625 POR SOLDADURA

Directory of Open Access Journals (Sweden)

JOSE MATOS

2012-01-01

Full Text Available El objetivo de este trabajo fue evaluar y caracterizar el comportamiento mecánico en desgaste del acero API 5L X65, revestido con niobio en comparación al desempeño del revestimiento de la aleación de inconel 625 empleados en la industria de petróleo y gas. El revestimiento de niobio fue obtenido por el proceso de aspersión térmica a plasma de arco no transferido y el revestimiento inconel 625 por soldadura con electrodo revestido. La resistencia al desgaste por abrasión fue evaluada según la norma Petrobras N-2568, en un tribómetro CTER, la rugosidad y el volumen de material desgastado se determinó a través de perfilometría y la dureza de los revestimientos por microscopia Vickers. Los revestimientos obtenidos fueron caracterizados respecto a su morfología por microscopia electrónica de barrido (MEB y microscopía óptica (MO. La mayor dureza del revestimiento con niobio obtenido puede haber contribuido a reducir la tasa de desgaste en comparación con el revestimiento de inconel 625.

Simulación de la formación de plasma en el mecanizado por electroerosión

OpenAIRE

Villagomez Galindo, Miguel; González Rojas, Hernan Alberto

2017-01-01

El proceso de mecanizado por electroerosión es una técnica de manufactura no convencional caracterizada por descargas eléctricas controladas que liberan tal cantidad de energía que es capaz de transformar en plasma el dieléctrico circundante al material conductor a mecanizar, con la consecuente sublimación del mismo, lo que provoca la remoción de material. En este trabajo se presenta la simulación de la formación de plasma debido a una sucesión de descargas eléctricas durante el p...

EXPERIMENTAL CHARACTERIZATION OF A MAGNETOHYDRODYNAMIC POWER GENERATOR UNDER DC ARC PLASMA

Directory of Open Access Journals (Sweden)

Ayokunle Oluwaseun Ayeleso

2018-02-01

Full Text Available The generation of electric power through the conventional systems (thermal and hydroelectric is no longer sufficient to meet the increasing industrial and commercial usage. Therefore, an alternative energy conversion system is currently being sought. The aim of the presented study is to develop a direct energy conversion system (Magnetohydrodynamics, MHD generator to generate electric power using plasma. Additionally, the generator electric response is investigated based on the Faraday’s principle of electromagnetism and fluid dynamics. For this purpose, a rectangular MHD generator prototype with segmented electrodes was constructed and subjected to continuous plasma from a DC arc source at test facilities available in the Western Cape region (South Africa. Subsequently, the terminal voltages at the middle-electrodes were measured one after another across 1, 100 and 470 Ω load resistors. In all experiments, the absolute time-averages of the measured terminal voltage across each load resistor were similar, which indicates a generation of power. The maximum power of the order 0.203mW was obtained when 1 Ω resistor was connected to the middle-electrodes. Conclusively, these results validate the measurement approach of the MHD generator with segmented electrodes and could be used to design a large MHD unit that can be incorporated to the existing conventional thermal plant to improve their cyclic thermal efficiency.

Uncapped silver nanoparticles synthesized by DC arc thermal plasma technique for conductor paste formulation

Science.gov (United States)

Shinde, Manish; Pawar, Amol; Karmakar, Soumen; Seth, Tanay; Raut, Varsha; Rane, Sunit; Bhoraskar, Sudha; Amalnerkar, Dinesh

2009-11-01

Uncapped silver nanoparticles were synthesized by DC arc thermal plasma technique. The synthesized nanoparticles were structurally cubic and showed wide particle size variation (between 20-150 nm). Thick film paste formulated from such uncapped silver nanoparticles was screen-printed on alumina substrates and the resultant `green' films were fired at different firing temperatures. The films fired at 600 °C revealed better microstructure properties and also yielded the lowest value of sheet resistance in comparison to those corresponding to conventional peak firing temperature of 850 °C. Our findings directly support the role of silver nanoparticles in substantially depressing the operative peak firing temperature involved in traditional conductor thick films technology.

FLYWHEEL AND A DC MACHINE

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IVAN ALCALÁ

2014-01-01

Full Text Available Este artículo describe el análisis, modelado y simulación de un vehículo eléctrico (EV enfocado al desarrollo de un banco de pruebas para reproducir la dinámica del EV. El banco está formado por un drive de motor de inducción (IM acoplado directamente a una máquina de DC y a un volante de inercia a través de una transmisión. El volante de inercia y la máquina de DC reproducen la dinámica y las fuerzas que actúan en el vehículo. Se propone una metodología para diseñar un banco de pruebas de EV para estudiar el comportamiento de vehículos eléctricos cercano a las condiciones de operación reales. El análisis de las fuerzas en el EV en conjunto con la máquina DC define las condiciones de operación del EV. El modelado y la simulación son desarrollados en MATLAB/Simulink, el banco de pruebas implementado es controlado por un DSP. Finalmente, los resultados de simulación y experimentales obtenidos validan el funcionamiento del banco de prueba.

V-I curves and plasma parameters in a high density DC glow discharge generated by a current-source

International Nuclear Information System (INIS)

Granda-Gutierrez, E E; Lopez-Callejas, R; Piedad-Beneitez, A de la; BenItez-Read, J S; Pacheco-Sotelo, J O; Pena-Eguiluz, R; A, R Valencia; Mercado-Cabrera, A; Barocio, S R

2008-01-01

Nitrogen DC glow discharges, conducted in a cylindrical geometry, have been characterized using a new current-source able to provide 10 -3 - 3 A for the sustainment of the discharge, instead of a conventional voltage-source. The V-I characteristic curves obtained from these discharges were found to fit the general form i(v) = A(p)v k(p) , whereby the plasma itself can be modeled as a voltage-controlled current-source. We conclude that the fitting parameters A and k, which mainly depend on the gas pressure p, are strongly related to the plasma characteristics, so much so that they can indicate the pressure interval in which the maximum plasma density is located, with values in the order of 10 16 m -3 at reduced discharge potential (300-600 V) and low working pressure (10 -1 - 10 1 Pa)

-3000 V dc bias Ti oxidation by inductively coupled plasma

International Nuclear Information System (INIS)

Valencia-Alvarado, R; Lopez-Callejas, R; Barocio, S R; Mercado-Cabrera, A; Pena-Eguiluz, R; Munoz-Castro, A E; De la Piedad-Beneitez, A; De la Rosa-Vazquez, J

2008-01-01

Broadening the outer oxidized layer of titanium by means of plasmas commands considerable interest in the biomedical research area due to its potential in human biocompatibility enhancement. Some early results of titanium substrate superficial oxidation experiments which have been conducted in a cylindrical vessel inductively coupled to a 13.56 MHz RF generator with a 500 W output are presented. The oxidation process was carried out in a 20 % oxygen and 80 % argon mixture at work pressures in the 5x10 -3 -1 mbar range, while the samples were dc biased down to -3000 V. The substrate temperature appears to be directly dependent on this voltage, reaching 685 deg. C at the maximum bias when a diffusive oxidation process gives rise to the TiO 2 and α-TiO rutile phases. These were characterized by means of x-ray diffraction and scanning electron microscopy revealing atomic percentage concentrations of oxygen, with respect to those of titanium, between 68 and 13 at.%. The optimum modified layer depth reached 5 μm at a 5x10 -2 mbar work pressure.

An optical emission spectroscopy study of the plasma generated in the DC HF CVD nucleation of diamond

Energy Technology Data Exchange (ETDEWEB)

Larijani, M.M. [Nuclear Research Centre for Agriculture and Medicine, AEOI, P.O. Box 31485-498, Karaj (Iran, Islamic Republic of)]. E-mail: mmojtahedzadeh@nrcam.org; Le Normand, F. [Groupe Surfaces-Interfaces, IPCMS, UMR 7504 CNRS, BP 20, 67037 Strasbourg Cedex 2 (France); Cregut, O. [Groupe Surfaces-Interfaces, IPCMS, UMR 7504 CNRS, BP 20, 67037 Strasbourg Cedex 2 (France)

2007-02-15

Optical emission spectroscopy (OES) was used to study the plasma generated by the activation of the gas phase CH{sub 4} + H{sub 2} both by hot filaments and by a plasma discharge (DC HF CVD) during the nucleation of CVD diamond. The effects of nucleation parameters, such as methane concentration and extraction potential, on the plasma chemistry near the surface were investigated. The density of the diamond nucleation and the quality of the diamond films were studied by scanning electron microscopy (SEM) and Raman scattering, respectively. The OES results showed that the methane concentration influenced strongly the intensity ratio of H{sub {beta}}-H{sub {alpha}} implying an increase of electron mean energy, as well as CH, CH{sup +}, C{sub 2}. A correlation between the relative increase of CH{sup +} and the diamond nucleation density was found, conversely the increase of C{sub 2} contributed to the introduction of defects in the diamond nuclei.

Characterization of In-Flight Processing of Alumina Powder Using a DC-RF Hybrid Plasma Flow System at Constant Low Operating Power

Science.gov (United States)

Nishiyama, H.; Onodera, M.; Igawa, J.; Nakajima, T.

2009-12-01

The aim of this study is to provide the optimum operating conditions for enhancing in-flight alumina particle heating as much as possible for particle spheroidization and aggregation of melted particles using a DC-RF hybrid plasma flow system even at constant low operating power based on the thermofluid considerations. It is clarified that the swirl flow and higher operating pressure enhance the particle melting and aggregation of melted particles coupled with increasing gas temperature downstream of a plasma uniformly in the radial direction at constant electrical discharge conditions.

Destruction of acenaphthene, fluorene, anthracene and pyrene by a dc gliding arc plasma reactor

International Nuclear Information System (INIS)

Yu Liang; Tu Xin; Li Xiaodong; Wang Yu; Chi Yong; Yan Jianhua

2010-01-01

In this study, four kinds of PAHs (polycyclic aromatic hydrocarbons) i.e. acenaphthene, fluorene, anthracene and pyrene are used as targets for investigation of PAHs treatment process assisted by dc gliding arc discharge. The effects of carrier gas and external resistance on the PAHs decomposition process are discussed. The results indicate that the destruction rate can be achieved to the highest with the carrier gas of oxygen and the external resistance of 50 kΩ independent of type of PAHs. Furthermore, experimental results suggest that destruction energy efficiency of gliding arc plasma would be improved by treating higher concentration pollutants. Based on the analysis of experimental results, possible destruction mechanisms in different gas discharge are discussed.

Effect of Feed Forms on the Results of Melting of Fly Ash by a DC Plasma Arc Furnace

International Nuclear Information System (INIS)

Chen Mingzhou; Meng Yuedong; Shi Jiabiao; Ni Guohua; Jiang Yiman; Yu Xinyao; Zhao Peng

2009-01-01

Fly ash from a municipal solid waste incinerator (MSWI) without preprocessing (original fly ash, OFA) was melted by a direct current (DC) plasma arc furnace to investigate how the feed forms governed the results. Dioxins in flue gas from stack and bag-filter ash (BFA) were detected. The distribution of heavy metals of Pb, Cd, As, and Cr along the flue gas process system was analyzed. Through a comparison of the results for dioxins and heavy metals in this study and previous work, carrying-over of fly ash particles with the flue gas stream can be deduced. Based on the magnetic induction equation and Navier-Stokes equations, a magnetohydrodynamic (MHD) model for the plasma arc was developed to describe the particle-carrying effect. The results indicate that, a. when melted, the feed forms of MSWI fly ash affect the results significantly; b. it is not preferable to melt MSWI fly ash directly, and efforts should be made to limit the mass transfer of OFA from the plasma furnace. (plasma technology)

Synthesis of SiO(x) powder using DC arc plasma.

Science.gov (United States)

Jung, Chan-Ok; Park, Dong-Wha

2013-02-01

SiO(x) was prepared by DC arc plasma and applied to the anode material of lithium ion batteries. A pellet of a mixture of Si and SiO2 was used as the raw material. The ratios of the silicon and silicon dioxide (SiO2) mixtures were varied by controlling the Si-SiO2 molar ratio (Si-SiO2 = 1-4). Hydrogen gas was used as the reduction atmosphere in the chamber. The prepared SiO(x) was collected on the chamber wall. The obtained SiO(x) was characterized by X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). XRD and TEM showed that the phase composition of the prepared particles was composed of amorphous SiO(x) and crystalline Si. The prepared SiO(x) showed wire and spherical morphology. XPS indicated the bonding state and 'x' value of the prepared SiO(x), which was close to one. The result of prepared SiO(x) is discussed from thermodynamic equilibrium calculations. The electrochemical behavior of the silicon monoxide anode was investigated.

DC electric springs with DC/DC converters

DEFF Research Database (Denmark)

Wang, Qingsong; Cheng, Ming; Jiang, Yunlei

2016-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2017-01-15

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

Destruction of acenaphthene, fluorene, anthracene and pyrene by a dc gliding arc plasma reactor.

Science.gov (United States)

Yu, Liang; Tu, Xin; Li, Xiaodong; Wang, Yu; Chi, Yong; Yan, Jianhua

2010-08-15

In this study, four kinds of PAHs (polycyclic aromatic hydrocarbons) i.e. acenaphthene, fluorene, anthracene and pyrene are used as targets for investigation of PAHs treatment process assisted by dc gliding arc discharge. The effects of carrier gas and external resistance on the PAHs decomposition process are discussed. The results indicate that the destruction rate can be achieved to the highest with the carrier gas of oxygen and the external resistance of 50 kOmega independent of type of PAHs. Furthermore, experimental results suggest that destruction energy efficiency of gliding arc plasma would be improved by treating higher concentration pollutants. Based on the analysis of experimental results, possible destruction mechanisms in different gas discharge are discussed. Copyright 2010 Elsevier B.V. All rights reserved.

[Automatic adjustment control system for DC glow discharge plasma source].

Science.gov (United States)

Wan, Zhen-zhen; Wang, Yong-qing; Li, Xiao-jia; Wang, Hai-zhou; Shi, Ning

2011-03-01

There are three important parameters in the DC glow discharge process, the discharge current, discharge voltage and argon pressure in discharge source. These parameters influence each other during glow discharge process. This paper presents an automatic control system for DC glow discharge plasma source. This system collects and controls discharge voltage automatically by adjusting discharge source pressure while the discharge current is constant in the glow discharge process. The design concept, circuit principle and control program of this automatic control system are described. The accuracy is improved by this automatic control system with the method of reducing the complex operations and manual control errors. This system enhances the control accuracy of glow discharge voltage, and reduces the time to reach discharge voltage stability. The glow discharge voltage stability test results with automatic control system are provided as well, the accuracy with automatic control system is better than 1% FS which is improved from 4% FS by manual control. Time to reach discharge voltage stability has been shortened to within 30 s by automatic control from more than 90 s by manual control. Standard samples like middle-low alloy steel and tin bronze have been tested by this automatic control system. The concentration analysis precision has been significantly improved. The RSDs of all the test result are better than 3.5%. In middle-low alloy steel standard sample, the RSD range of concentration test result of Ti, Co and Mn elements is reduced from 3.0%-4.3% by manual control to 1.7%-2.4% by automatic control, and that for S and Mo is also reduced from 5.2%-5.9% to 3.3%-3.5%. In tin bronze standard sample, the RSD range of Sn, Zn and Al elements is reduced from 2.6%-4.4% to 1.0%-2.4%, and that for Si, Ni and Fe is reduced from 6.6%-13.9% to 2.6%-3.5%. The test data is also shown in this paper.

Influência da energia de soldagem em uniões de lâminas finas através de laser pulsado de Nd:YAG Effect of the heat input on pulsed Nd:YAG laser welding of thin foil

Directory of Open Access Journals (Sweden)

Vicente A. Ventrella

2010-12-01

Full Text Available A soldagem laser vem sendo utilizada como um importante processo de manufatura. Ela pode ser utilizada tanto no modo contínuo quanto no modo pulsado. No processo onde se utiliza laser pulsado é possível realizar soldas de costura em lâminas finas, através da sobreposição dos pulsos. Nesse caso a velocidade de soldagem é definida pela taxa de sobreposição, taxa de repetição e diâmetro do pulso. A soldagem de sobreposição de lâminas finas apresenta problemas típicos como distorção excessiva da junta soldada, falta de contato entre as lâminas a serem soldadas (presença de um gap de ar, perfuração da junta e presença de altos níveis de tensões residuais. O processo de laser pulsado é preferido em relação ao processo por laser contínuo, pois ele possibilita um melhor controle da energia de soldagem. O presente trabalho estudou a influência da energia do pulso, no caso processo de soldagem laser Nd:YAG, na soldagem de lâminas finas ( 100µm de aço inoxidável austenítico AISI 316L, utilizado no revestimento de sensores (que trabalham em ambiente corrosivo da indústria sucroalcooleira. Utilizou-se energia de pulso de 1,0 a 2,25 Joules, com incremento de 0,25 Joules e largura temporal de 4 ms. As soldas foram realizadas com proteção gasosa de argônio. Foram realizadas análises macrográficas das juntas soldadas, através de secções transversais das mesmas e, ensaios de microdureza Vickers e ensaios de tração. Os resultados obtidos mostraram que o controle da energia do pulso, em processo de soldagem por laser de lâminas finas é de fundamental importância para a geração de juntas soldadas com boas propriedades mecânicas e livres de descontinuidades. O limite de resistência da junta soldada aumentou no início e depois sofreu um pequeno decréscimo em função do aumento da energia do pulso. O processo mostrou-se muito sensível à presença de gap entre as lâminas.Laser beam welding has been used widely

Plasma vitrification program for radioactive waste treatment

International Nuclear Information System (INIS)

Hung, Tsungmin; Tzeng, Chinchin; Kuo, Pingchun

1998-01-01

In order to treat radioactive wastes effectively and solve storage problems, INER has developed the plasma arc technology and plasma process for various waste forms for several years. The plasma vitrification program is commenced via different developing stages through nine years. It includes (a) development of non-transferred DC plasma torch, (b) establishment of a lab-scale plasma system with home-made 100kW non-transferred DC plasma torch, (c) testing of plasma vitrification of simulated radioactive wastes, (d) establishment of a transferred DC plasma torch delivering output power more than 800 kW, (e) study of NOx reduction process for the plasma furnace, (f) development of a pilot-scale plasma melting furnace to verify the vitrification process, and (g) constructing a plasma furnace facility in INER. The final goal of the program is to establish a plasma processing plant with capacity of 250 kg/hr to treat the low-level radioactive wastes generated from INER itself and domestic institutes due to isotope applications. (author)

Advanced DC/DC converters

CERN Document Server

Luo, Fang Lin

2003-01-01

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

Magnetic properties of Co-N films deposited by ECR nitrogen/argon plasma with DC negative-biased Co target

Energy Technology Data Exchange (ETDEWEB)

Li, H.; Zhang, Y.C.; Yang, K.; Liu, H.X.; Zhu, X.D., E-mail: xdzhu@ustc.edu.cn; Zhou, H.Y.

2017-06-01

Highlights: • A new method of synthesizing Co-N films containing Co{sub 4}N phase. • Tunable magnetic properties achieved in ECR plasma CVD. • The change of magnetic properties is related to atoms mobility on substrate and the concentration of active species in plasma vapor. - Abstract: By introducing DC negative-biased Co target in the Electron Cyclotron Resonance (ECR) nitrogen/argon plasma, the Co-N films containing Co{sub 4}N phase were synthesized on Si(100) substrate. Effects of processing parameters on magnetic properties of the films are investigated. It is found that magnetic properties of Co-N films vary with N{sub 2}/Ar flow ratio, substrate temperature, and target biasing voltage. The saturation magnetization M{sub s} decreased by increasing the N{sub 2}/Ar gas flow ratio or decreasing target biasing voltage, while the coercive field H{sub c} increased, which is ascribed to the variation of relative concentration for N or Co active species in plasma vapor. The magnetic properties present complex dependency with growth temperature, which is related to the atom mobility on the substrate affected by the growth temperature. This study exhibits a potential of ECR plasma chemical vapor deposition to synthesize the interstitial compounds and tune magnetic properties of films.

Pulsed-DC selfsputtering of copper

International Nuclear Information System (INIS)

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

2008-01-01

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

Pulsed-DC selfsputtering of copper

Science.gov (United States)

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

2008-03-01

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

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

International Nuclear Information System (INIS)

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

2004-01-01

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

A Unidirectional DC-DC Autotransformer for DC Grid Application

Directory of Open Access Journals (Sweden)

Meng Zhou

2018-03-01

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

Influencia de la transferencia en la resistencia y dureza de las uniones soldadas obtenidas por el proceso de soldadura GMAW

Directory of Open Access Journals (Sweden)

Sandra Patricia Romero Nieto

2013-04-01

Full Text Available Este trabajo describe el comportamiento del proceso de soldadura GMAW con alambre compuesto de núcleo metálico, en uniones soldadas de acero ASTM A131, grado AH 32, utilizando dos composiciones de gas de protección y las transferencias de arco pulsado y corto circuito. Las propiedades mecánicas y la microestructura se evaluaron y los resultados indican que se logra mayor resistencia a la tensión y, a su vez, un perfil de dureza más homogéneo utilizando la transferencia de arco pulsado. Asimismo, se establece que la porosidad en el pie de soldadura de las uniones en T con depósito en filete se relaciona con la longitud de arco.

TCABR Tokamak scrape-off layer turbulence with DC biasing

International Nuclear Information System (INIS)

Heller, M.V.A.P.; Ferreira, A.A.; Caldas, I.L.; Nascimento, I.C.

2004-01-01

Turbulence and particle transport in plasma scrape-off layer have been controlled by external electric fields. This control can be achieved by a biasing electrode located inside the plasma. We investigate plasma turbulence changes in the scrape-off layer of TCABR tokamak introduced by DC biasing an electrode inside the plasma. Our investigation is based on the alterations observed on the wavelet power spectra and on the intermittent burst sequences of plasma potential and density fluctuations measured by a set of Langmuir probes. Biasing the electrode changes the turbulence statistics and the bursts intermittence. With the imposed external electric field, fluctuation amplitudes, phase velocities, and anomalous particle transport are modified. Transport reduction for higher frequencies induced by the biasing could be due to the strong de-phasing between density and potential fluctuations. The mode coupling increases with the perturbation for the high frequency broadband fluctuations. The total (laminar and bursting) radial particle transport is reduced by about 25% by DC biasing. Bursts contribution to total transport is 15% and for the studied conditions this contribution does not change much with the bias perturbation

Preparation of Ag-containing diamond-like carbon films on the interior surface of tubes by a combined method of plasma source ion implantation and DC sputtering

Science.gov (United States)

Hatada, R.; Flege, S.; Bobrich, A.; Ensinger, W.; Dietz, C.; Baba, K.; Sawase, T.; Watamoto, T.; Matsutani, T.

2014-08-01

Adhesive diamond-like carbon (DLC) films can be prepared by plasma source ion implantation (PSII), which is also suitable for the treatment of the inner surface of a tube. Incorporation of a metal into the DLC film provides a possibility to change the characteristics of the DLC film. One source for the metal is DC sputtering. In this study PSII and DC sputtering were combined to prepare DLC films containing low concentrations of Ag on the interior surfaces of stainless steel tubes. A DLC film was deposited using a C2H4 plasma with the help of an auxiliary electrode inside of the tube. This electrode was then used as a target for the DC sputtering. A mixture of the gases Ar and C2H4 was used to sputter the silver. By changing the gas flow ratios and process time, the resulting Ag content of the films could be varied. Sample characterizations were performed by X-ray photoelectron spectroscopy, secondary ion mass spectrometry, atomic force microscopy and Raman spectroscopy. Additionally, a ball-on-disk test was performed to investigate the tribological properties of the films. The antibacterial activity was determined using Staphylococcus aureus bacteria.

Experiments on cleaning effects of TDC, GDC and ECR-DC in the JFT-2M tokamak

International Nuclear Information System (INIS)

Matsuzaki, Y.; Ogawa, H.; Miura, Y.; Ohtsuka, H.; Suzuki, N.; Yamauchi, T.; Tani, T.; Mori, M.

1987-01-01

The cleaning effects of Taylor-type discharge cleaning (TDC), glow discharge cleaning (GDC) and ECR discharge cleaning (ECR-DC) were studied in the JFT-2M tokamak by comparing the properties of resulting tokamak plasmas, by observing the surface composition of samples and by residual gas analysis. The operational parameters of the three discharge cleaning techniques were as follows; the plasma current for TDC is 20 kA, the DC current for GDC is 3 A and the RF power for ECR-DC is 2.3 kW. Parameters of the tokamak plasmas such as loop voltages, radiation losses, spectra emission of oxygen, maximum mean electron densities and profiles of electron temperature were improved as the TDC and ECR-DC proceeded. Changes in the surface composition of samples were measured by Auger electron spectrosopy. The results showed that during the TDC and ECR-DC oxygen was reduced, while GDC reduced mainly carbon. Residual gas analysis performed during discharge cleaning corroborated these results. (orig.)

Effect of Feed Forms on the Results of Melting of Fly Ash by a DC Plasma Arc Furnace

Science.gov (United States)

Chen, Mingzhou; Meng, Yuedong; Shi, Jiabiao; Ni, Guohua; Jiang, Yiman; Yu, Xinyao; ZHAO, Peng

2009-10-01

Fly ash from a municipal solid waste incinerator (MSWI) without preprocessing (original fly ash, OFA) was melted by a direct current (DC) plasma arc furnace to investigate how the feed forms governed the results. Dioxins in flue gas from stack and bag-filter ash (BFA) were detected. The distribution of heavy metals of Pb, Cd, As, and Cr along the flue gas process system was analyzed. Through a comparison of the results for dioxins and heavy metals in this study and previous work, carrying-over of fly ash particles with the flue gas stream can be deduced. Based on the magnetic induction equation and Navier-Stokes equations, a magnetohydrodynamic (MHD) model for the plasma arc was developed to describe the particle-carrying effect. The results indicate that, a. when melted, the feed forms of MSWI fly ash affect the results significantly; b. it is not preferable to melt MSWI fly ash directly, and efforts should be made to limit the mass transfer of OFA from the plasma furnace.

Influence of dust particles on the neon spectral line intensities at the uniform positive column of dc discharge at the space apparatus “Plasma Kristall-4”

Science.gov (United States)

Usachev, A. D.; Zobnin, A. V.; Shonenkov, A. V.; Lipaev, A. M.; Molotkov, V. I.; Petrov, O. F.; Fortov, V. E.; Pustyl'nik, M. Y.; Fink, M. A.; Thoma, M. A.; Thomas, H. M.; Padalka, G. I.

2018-01-01

Influence of the elongated dust cloud on the intensities of different neon spectral lines in visible and near ir spectral ranges in the uniform positive column has been experimentally investigated using the Russian-European space apparatus “Plasma Kristall-4” (SA PK-4) on board of the International Space Station (ISS). The investigation was performed in the low pressure (0.5 mbar) direct current (dc, 1 mA) gas discharge in neon. Microgravity allowed us to perform experiments with a large dust cloud in the steady-state regime. To avoid the dust cloud drift in the dc electric field a switching dc polarity discharge mode has been applied. During the experiment a dust cloud of 9 mm in diameter in the discharge tube of 30 mm in diameter with the length of about 100 mm has been observed in the steady-state regime. In this regard, the intensities of neon spectral lines corresponding to 3p → 3s electronic transitions have increased by a factor of 1.4 times, while the intensities of neon spectral lines corresponding to 3d → 3p electronic transitions have increased by a factor of 1.6 times. The observed phenomenon is explained on the basis of the Schottky approach by a self-consistent rising dc electric field in the dusty plasma cloud resulting in an increase of the electron temperature.

Numerical simulation of heat transfer and fluid flow in a DC plasma-arc device for waste thermal treatment

International Nuclear Information System (INIS)

Deng, Jing; Li, Yaojian; Xu, Yongxiang; Sheng, Hongzhi

2010-01-01

In this work, Magnetic Fluid dynamics (MHD) model is used to stimulate the electromagnetic field, heat transfer and fluid flow in a DC non-transferred arc plasma torch. Through the coupled iterative computation about the electromagnetic equations described by magnetic vector potential format and the modified fluid dynamics equations, the electric potential, temperature and velocity distributions in the torch are obtained. The fluid-solid coupled computation method is applied to treat the electric current and heat transfer at the interface between the electrodes and fluid. The location of arc root attachment at the inside surface of anode and the arc voltage of the torch that we have predicted are very consistent with the corresponding experimental results. The calculated results of the torch are applied to the numerical simulation of the plasma jets under the laminar and turbulent condition. (author)

A resonant dc-dc power converter assembly

DEFF Research Database (Denmark)

2015-01-01

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

Intermittent Coffee Drying in Deep Bed with Pulsed Airflow Secado de Café en Lecho Fijo con Intermitencia Térmica y Flujo de Aire Pulsado

Directory of Open Access Journals (Sweden)

Héctor José Ciro Velásquez

2011-12-01

Full Text Available A dryer in deep bed without airflow reversal was adapted to work simultaneously with thermal intermittence and pulsed airflow in the drying of parchment coffee bean. The dryer was operated by cycles of thermal intermittence for a heating temperature of 55 °C and cooling of 40 and 25 °C. The results showed that the increase of temperature in the cycle of cooling tends to increase the water removal and that the increase of the number of air pulses without reversal of the direction of air flow causes an excessive moisture gradient within the batch. Moreover, the specific energy requirement of the dryer was from 15 to 25 MJ/kg, showing the best thermal performance for the condition in which the dryer was operate without pulsed airflow.Un secador de lecho fijo fue adaptado para trabajar de forma simultánea con intermitencia térmica y flujo de aire pulsado sin inversión de flujo de aire, en el secado de granos de café. El secador fue operado con ciclos de intermitencia térmica para una temperatura de calentamiento de 55 °C y enfriamiento de 40 y 25 °C. Los resultados mostraron que el aumento de temperatura en el ciclo de enfriamiento, tiende a incrementar la remoción de agua y que el aumento del número de pulsos de aire sin inversión del flujo de dirección del aire, ocasiona un secado deficiente debido al excesivo gradiente de humedad ocasionado en la capa de producto. Adicionalmente, se encontró que el consumo de energía específica del secador varió entre 15 y 25 MJ/kg de agua evaporada, siendo el mejor rendimiento termo energético para la condición en la cual el secador fue operado sin flujo de aire pulsado.

Step-Up DC-DC converters

DEFF Research Database (Denmark)

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

2017-01-01

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

The improvement of the detection power of a U-shaped DC plasma

Directory of Open Access Journals (Sweden)

DRAGAN MARKOVIC

2001-04-01

Full Text Available Optimization of the operating parameters of U-shpaed DC arc plasma and spectrometer parameters has been undertaken to explore the possibilities of improving its detection power. It is demonstrated, with a U-shaped arc as an example, that the limits of detection, in addition to well-defined parameters as described by Boumans and Winge, depend on the signal integration time. It is shown that with increasing integration time, the limits of detection are decreased within some limits and that the precision and concentration sensitivity are improved as well. A mathematical expression for the dependence of the detection limit on the integration time is presented. To increase the reliability of the measurement of the mentioned parameters, the working conditions were optimized for the following analytes: Ag, Al, Au, Cr, Fe, Mn, Ni, Pb, Pd, Pt, and V. The obtained limits of detection are comparable or better than those obtained by ICP for the elements studied. Itwas estimed that the possibility exists for their further improvement up to 10 times.

A resonant dc-dc power converter assembly

OpenAIRE

Madsen, Mickey Pierre

2015-01-01

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

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

Science.gov (United States)

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

2018-01-01

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

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

International Nuclear Information System (INIS)

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

2004-01-01

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

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

International Nuclear Information System (INIS)

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

2008-01-01

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

DC plasma ion implantation in an inductively coupled RF plasma

International Nuclear Information System (INIS)

Silawatshananai, C.; Matan, N.; Pakpum, C.; Pussadee, N.; Srisantitam, P.; Davynov, S.; Vilaithong, T.

2004-01-01

Various modes of plasma ion implantation have been investigated in a small inductively coupled 13.6 MHz RF plasma source. Plasma ion implantation with HVDC(up to -10 kV bias) has been investigated in order to incorporate with the conventional implantation of diamond like carbon. In this preliminary work, nitrogen ions are implanted into the stainless steel sample with a dose of 5.5 x 10 -2 cm for a short implanting time of 7 minutes without target cooling. Surface properties such as microhardness, wear rate and the friction coefficient have been improved. X-ray and SEM analyses show distinct structural changes on the surface. A combination of sheath assisted implantation and thermal diffusion may be responsible for improvement in surface properties. (orig.)

Step-Up DC-DC converters

DEFF Research Database (Denmark)

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

2017-01-01

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

Desempenho físico-químico de filmes hidrofóbicos de AlN e de Ti nanoestruturado crescidos por plasma frio sobre superfícies de isoladores cerâmicos de porcelana tipo pino

Directory of Open Access Journals (Sweden)

M. M. Mazur

2016-03-01

Full Text Available Resumo A resistência mecânica e a propriedade dielétrica de isoladores cerâmicos são características fundamentais para o suporte das redes de distribuição de energia elétrica. Porém, tanto a umidade quanto o teor de poluentes na atmosfera podem vir a ser prejudiciais e causar falhas na entrega de energia por elevação da sua corrente elétrica de fuga. O vidrado do isolador tem grande afinidade com a água resultante da interação da superfície do vidro com a atmosfera. No presente trabalho, foi realizada a deposição de filmes de nitreto de alumínio sobre o vidrado de amostras de isoladores elétricos cerâmicos, via plasma "magnetron sputtering" pulsado, de corrente contínua, e com uma mistura dos gases argônio e nitrogênio e de Ti sobre isoladores tipo pino para classes de tensão de 15 kV. A morfologia dos filmes e o desempenho dos isoladores foram medidos por MEV-FEG/EDS, AFM, máxima corrente de fuga RMS e grau de hidrofobicidade. O comportamento dos filmes depositados medido pelo grau de hidrofobicidade reduziu nas amostras de CM6 para CM4, com AlN, e de CM7 para CM3 quando foi depositado o Ti. A máxima corrente de fuga RMS medida nos isoladores sem e com filme nanométrico à base de Ti foi superior nos dispositivos sem a proteção, alcançando valores medidos de 5 mA e com desligamento do sistema computadorizado de medida (após 3 dias em Sauípe e 3 meses em Pituba em consequência desta ter superado o intervalo de segurança de curto circuito estabelecido nos dispositivos eletrônicos de proteção (surtos superiores a 300 mA. Com a deposição dos filmes em 7 isoladores, foram verificadas alterações de comportamento em dois destes, com picos de máxima corrente de fuga atingindo 2,4 mA no campo. A maioria dos isoladores analisados teve como variações de correntes de fuga RMS, no período de medida, entre 0,2 e 2 mA, em condições adversas de clima (com chuva e diferentes velocidades de vento.

D.C. Arcjet Diamond Deposition

Science.gov (United States)

Russell, Derrek Andrew

1995-01-01

Polycrystalline diamond films synthesized by a D.C. (direct current) arcjet device was reported for the first time in 1988. This device is capable of higher diamond growth rates than any other form of diamond CVD (chemical vapor deposition) process due to its inherent versatility with regard to the enthalpy and fluid properties of the diamond-depositing vapor. Unfortunately, the versatility of this type of device is contrasted by many difficulties such as arc stability and large heat fluxes which make applying it toward diamond deposition a difficult problem. The purpose of this work was to convert the dc arcjet, which is primarily a metallurgical device, into a commercially viable diamond CVD process. The project was divided into two parts: process development and diagnostics. The process development effort concentrated on the certain engineering challenges. Among these was a novel arcjet design that allowed the carbon-source gas to be injected downstream of the tungsten cathode while still facilitating mixture with the main gas feed. Another engineering accomplishment was the incorporation of a water -cooled substrate cooler/spinner that maintained the substrate at the proper temperature, provided the substrate with a large thermal time constant to reduce thermal shock of the diamond film, and enabled the system to achieve a four -inch diameter growth area. The process diagnostics effort concentrated on measurements aimed at developing a fundamental understanding of the properties of the plasma jet such as temperature, plasma density, Mach number, pressure at the substrate, etc. The plasma temperature was determined to be 5195 K by measuring the rotational temperature of C _2 via optical emission spectroscopy. The Mach number of the plasma jet was determined to be ~6.0 as determined by the ratio of the stagnation pressures before and after the shock wave in the plasma jet. The C_2 concentration in the plasma jet was determined to be {~10 }^{12} cm^ {-3} by

Diagnostics of ballistic electrons in a dc/rf hybrid capacitively coupled discharge

International Nuclear Information System (INIS)

Xu Lin; Chen, Lee; Funk, Merritt; Ranjan, Alok; Hummel, Mike; Bravenec, Ron; Sundararajan, Radha; Economou, Demetre J.; Donnelly, Vincent M.

2008-01-01

The energy distribution of ballistic electrons in a dc/rf hybrid parallel-plate capacitively coupled plasma reactor was measured. Ballistic electrons originated as secondaries produced by ion and electron bombardment of the electrodes. The energy distribution of ballistic electrons peaked at the value of the negative bias applied to the dc electrode. As that bias became more negative, the ballistic electron current on the rf substrate electrode increased dramatically. The ion current on the dc electrode also increased

Direct-current cathodic vacuum arc system with magnetic-field mechanism for plasma stabilization.

Science.gov (United States)

Zhang, H-S; Komvopoulos, K

2008-07-01

Filtered cathodic vacuum arc (FCVA) deposition is characterized by plasma beam directionality, plasma energy adjustment via substrate biasing, macroparticle filtering, and independent substrate temperature control. Between the two modes of FCVA deposition, namely, direct current (dc) and pulsed arc, the dc mode yields higher deposition rates than the pulsed mode. However, maintaining the dc arc discharge is challenging because of its inherent plasma instabilities. A system generating a special configuration of magnetic field that stabilizes the dc arc discharge during film deposition is presented. This magnetic field is also part of the out-of-plane magnetic filter used to focus the plasma beam and prevent macroparticle film contamination. The efficiency of the plasma-stabilizing magnetic-field mechanism is demonstrated by the deposition of amorphous carbon (a-C) films exhibiting significantly high hardness and tetrahedral carbon hybridization (sp3) contents higher than 70%. Such high-quality films cannot be produced by dc arc deposition without the plasma-stabilizing mechanism presented in this study.

Direct-current cathodic vacuum arc system with magnetic-field mechanism for plasma stabilization

International Nuclear Information System (INIS)

Zhang, H.-S.; Komvopoulos, K.

2008-01-01

Filtered cathodic vacuum arc (FCVA) deposition is characterized by plasma beam directionality, plasma energy adjustment via substrate biasing, macroparticle filtering, and independent substrate temperature control. Between the two modes of FCVA deposition, namely, direct current (dc) and pulsed arc, the dc mode yields higher deposition rates than the pulsed mode. However, maintaining the dc arc discharge is challenging because of its inherent plasma instabilities. A system generating a special configuration of magnetic field that stabilizes the dc arc discharge during film deposition is presented. This magnetic field is also part of the out-of-plane magnetic filter used to focus the plasma beam and prevent macroparticle film contamination. The efficiency of the plasma-stabilizing magnetic-field mechanism is demonstrated by the deposition of amorphous carbon (a-C) films exhibiting significantly high hardness and tetrahedral carbon hybridization (sp 3 ) contents higher than 70%. Such high-quality films cannot be produced by dc arc deposition without the plasma-stabilizing mechanism presented in this study

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

Science.gov (United States)

2010-05-04

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

Recubrimientos protectores para componentes de turbinas de aviación y de generación de energía depositados por proyección por plasma

Directory of Open Access Journals (Sweden)

Agüero Bruna, A.

2000-08-01

Full Text Available Coatings produced by aluminium diffusion, called aluminide are employed to increase the oxidation and corrosion resistance, increasing the life of Ni and Co base superalloys components at temperatures comprised between 900 and 1050ºC. Consequently these coatings are frequently employed in aeronautic and power generation turbines as well as in the chemical industry. Aluminides are industrially produced by pack cementation or CVD and recently it has been demonstrated that its resistance significantly increases when Cr is added (chrome-aluminides. During this work, a feasibility study has been carried out in order to determine if plasma spray can be employed for depositing this type of coatings on turbine blades. Therefore, aluminium and aluminium/chromium layers were deposited on Ni base IN100 superalloy specimens that were subsequently subjected to a diffusion heat treatment under Ar flow. Characterisation and analysis of the coatings were carried out by metallography , SEM and EDS. Cyclic oxidation tests were carried out at 1050º C while molten sulphate hot corrosion was performed at 900º C. The results of this preliminary study are promising and indicate that plasma spray can be developed as an industrial process for production of aluminide and chrome-aluminide coatings.

Los recubrimientos producidos por difusión de aluminio, llamados aluminuros, se emplean para aumentar la resistencia a la oxidación y a la corrosión, incrementando la vida de componentes fabricados con superaleaciones de níquel y cobalto a temperaturas comprendidas entre 900 y 1050º C. Por ello se emplean muy frecuentemente en turbinas aeronaúticas y de producción de energía y en la industria química. Los aluminuros se obtienen industrialmente mediante cementación o CVD y recientemente se ha demostrado que su resistencia aumenta significativamente cuando se añade cromo (cromoaluminuros. Durante el presente trabajo, se ha realizado un estudio de viabilidad

Resistencia antimicrobiana y epidemiología molecular de aislamientos de Staphylococcus pseudintermedius de muestras clínicas de caninos

OpenAIRE

Vigo, Germán B.; Giacoboni, Gabriela I.; Gagetti, Paula S.; Pasterán, Fernando G.; Corso, Alejandra C.

2015-01-01

Se estudiaron 28 aislamientos obtenidos de muestras clínicas de perros e identificados por espectrometría de masas (MALDI-TOF) como Staphylococcus pseudintermedius; el objetivo fue evaluar la sensibilidad a los antimicrobianos por el método de difusión y establecer la relación clonal entre aislamientos por electroforesis en campo pulsado (PFGE). La resistencia a meticilina se evaluó mediante PCR por amplificación del gen mecA y se observó en 3/28 aislamientos (10,7 %). Quince aislamientos (53...

Effect of Low-Pressure Nitrogen DC Plasma Treatment on the Surface Properties of Biaxially Oriented Polypropylene, Poly (Methyl Methacrylate) and Polyvinyl Chloride Films

International Nuclear Information System (INIS)

Mortazavi, S. Hamideh; Ghoranneviss, Mahmood; Pilehvar, Soheil; Esmaeili, Sina; Zargham, Shamim; Hashemi, S. Ebrahim; Jodat, Hamzeh

2013-01-01

In this study, commercial biaxially oriented polypropylene (BOPP), polyvinyl chloride (PVC) and poly (methyl methacrylate) (PMMA) films were treated with nitrogen plasma over different exposure times in a Pyrex tube surrounded by a DC variable magnetic field. The chemical changes that appeared on the surface of the samples were investigated using Fourier transform infrared (FT-IR) spectroscopy and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy after treatment for 2 min, 4 min and 6 min in a nitrogen plasma chamber. Effects of the plasma treatment on the surface topographies and contact angles of the untreated and plasma treated films were also analyzed by atomic force microscopy (AFM) and a contact angle measuring system. The results show that the plasma treated films become more hydrophilic with an enhanced wettability due to the formation of some new polar groups on the surface of the treated films. Moreover, at higher exposure times, the total surface energy in all treated films increased while a reduction in contact angle occurred. The behavior of surface roughness in each sample was completely different at higher exposure times. (plasma technology)

Dusty plasma phase in a steady state plasma device

International Nuclear Information System (INIS)

Liang Xiaoping; Zheng Jian; Ma Jinxiu; Liu Wangdong; Zhuang Ge; Xie Jinlin; Wang Congrong; Yu Changxuan

2000-01-01

A DC discharge dusty plasma device used for study of waves in dusty plasma is introduced. A dusty plasma column is produced with about 30 cm in length and about 8.4 cm in diameter. The electron saturation current of Langmuir probe is obviously decreasing while the dust grains are present in the plasma. The negative charge on dust grains is directly proportional to the rotation rate of the dispenser. And the dust grains carry up to 40% of the negative charges in the whole plasma

Distribution of Fe atom density in a dc magnetron sputtering plasma source measured by laser-induced fluorescence imaging spectroscopy

Science.gov (United States)

Shibagaki, K.; Nafarizal, N.; Sasaki, K.; Toyoda, H.; Iwata, S.; Kato, T.; Tsunashima, S.; Sugai, H.

2003-10-01

Magnetron sputtering discharge is widely used as an efficient method for thin film fabrication. In order to achieve the optimized fabrication, understanding of the kinetics in plasmas is essential. In the present work, we measured the density distribution of sputtered Fe atoms using laser-induced fluorescence imaging spectroscopy. A dc magnetron plasma source with a Fe target was used. An area of 20 × 2 mm in front of the target was irradiated by a tunable laser beam having a planar shape. The picture of laser-induced fluorescence on the laser beam was taken using an ICCD camera. In this way, we obtained the two-dimensional image of the Fe atom density. As a result, it has been found that the Fe atom density observed at a distance of several centimeters from the target is higher than that adjacent to the target, when the Ar gas pressure was relatively high. It is suggested from this result that some gas-phase production processes of Fe atoms are available in the plasma. This work has been performed under the 21st Century COE Program by the Ministry of Education, Culture, Sports, Science and Technology in Japan.

DC Home Appliances for DC Distribution System

Directory of Open Access Journals (Sweden)

MUHAMMAD KAMRAN

2017-10-01

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

Characterization of DC magnetron plasma in Ar/Kr/N2 mixture during deposition of (Cr,Al)N coating

International Nuclear Information System (INIS)

Bobzin, K; Bagcivan, N; Theiß, S; Brugnara, R; Bibinov, N; Awakowicz, P

2017-01-01

Reactive sputter deposition of (Cr,Al)N coatings in DC magnetron plasmas containing Ar/Kr/N 2 mixtures is characterized by applying a combination of voltage–current measurement, optical emission spectroscopy (OES) and numerical simulation. Theoretical and experimental methods supplement each other and their combination permits us to obtain the most reliable information about the processes by physical vapor deposition. Gas temperature ( T g ) and plasma parameters, namely electron density n e and electron temperature T e are determined by spatial resolved measurements of molecular nitrogen photoemission. Steady-state densities of Cr and Al atoms are measured using OES. The sputtering of Cr and Al atoms is simulated using the TRIDYN code, measured electric current and applied voltage. Transport of sputtered atoms through the plasma volume is simulated by adopting a Monte-Carlo code. In order to quantify the ‘poisoning’ of the target surface with nitrogen, simulated steady state densities of Al and Cr atoms at different states of poisoning and at different distances from the target are compared with the measured densities. In addition, simulated fluxes of Cr and Al atoms to the substrate are compared with the measured deposition rates of the (Cr,Al)N coating. (paper)

Graphite electrode dc arc technology development for treatment of buried wastes

International Nuclear Information System (INIS)

Surma, J.E.; Cohn, D.R.; Smatlak, D.L.; Thomas, P.; Woskov, P.P.

1993-02-01

A ''National Laboratory-University-Industrial'' three-way partnership has been established between the Pacific Northwest Laboratory (PNL), Massachusetts Institute of Technology (MIT), and Electro-Pyrolysis, Inc. (EPI) to develop graphite electrode DC arc technology for the treatment of buried wastes. This paper outlines the PNL-MIT-EPI program describing a series of engineering-scale DC arc furnace tests conducted in an EPI furnace at the Plasma Fusion Center at MIT, and a description of the second phase of this program involving the design, fabrication, and testing of a pilot-scale DC arc furnace. Included in this work is the development and implementation of diagnostics to evaluate and optimize high temperature thermal processes such as the DC arc technology

Family of multiport bidirectional DC-DC converters

NARCIS (Netherlands)

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

2006-01-01

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

Tratamento da superfície de cateteres de poliamida 11 por plasma de oxigênio

Directory of Open Access Journals (Sweden)

Gean V. Salmoria

2013-01-01

Full Text Available A poliamida 11, assim como grande parte dos polímeros empregados na construção de dispositivos minimamente invasivos de uso médico, não apresenta significativa interação com líquidos polares, o que limita seu uso em algumas aplicações, uma vez que a maioria dos tecidos biológicos internos apresenta caráter hidrofílico (alta afinidade por água. No presente trabalho, investigou-se a influência do processo de tratamento por plasma de oxigênio da superfície da poliamida 11 sobre a composição, rugosidade e a hidrofilicidade. Através do tratamento, as características do material foram alteradas de forma a favorecer a adesão de uma camada polimérica hidrofílica sobre sua superfície, aumentando a hidrofilicidade e, consequentemente, a biocompatibilidade do dispositivo polimérico. Cateteres de poliamida 11 foram submetidos a diferentes tempos de exposição ao plasma, gerado sob uma atmosfera de oxigênio com pressão, temperatura e voltagem constante. Para isso, foram realizadas análises de espectroscopia de infravermelho, microscopia eletrônica de varredura e medida do ângulo de molhamento por água na superfície do polímero. As amostras tratadas e não tratadas (controle foram caracterizadas e constatou-se um aumento na rugosidade e no ângulo de contato, indicando uma possível melhora da aderência da camada polimérica hidrofílica a ser depositada.

BaltDC: purification, characterization and infrared spectroscopy of an antiplatelet DC protein isolated from Bothrops alternatus snake venom.

Science.gov (United States)

Matias, Mariana Santos; de Sousa, Bruna Barbosa; da Cunha Pereira, Déborah Fernanda; Dias, Edigar Henrique Vaz; Mamede, Carla Cristine Neves; de Queiroz, Mayara Ribeiro; Silva, Anielle Christine Almeida; Dantas, Noelio Oliveira; Soares, Andreimar Martins; de Oliveira Costa, Júnia; de Oliveira, Fábio

2017-01-01

Snake venoms are a complex mixture of proteins, organic and inorganic compounds. Some of these proteins, enzymatic or non-enzymatic ones, are able to interact with platelet receptors, causing hemostatic disorders. The possible therapeutic potential of toxins with antiplatelet properties may arouse interest in the pharmacological areas. The present study aimed to purify and characterize an antiplatelet DC protein from Bothrops alternatus snake venom. The protein, called BaltDC (DC protein from B. alternatus snake venom), was purified by a combination of ion-exchange chromatography on DEAE-Sephacel column and gel filtration on Sephadex G-75. The molecular mass was estimated by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS-PAGE). The amino acid sequence of the N-terminal region was carried out by Edman degradation method. Platelet aggregation assays were performed in human platelet-rich plasma (PRP). Infrared (IR) spectroscopy was used in order to elucidate the interactions between BaltDC and platelet membrane. BaltDC ran as a single protein band on SDS-PAGE and showed apparent molecular mass of 32 kDa under reducing or non-reducing conditions. The N-terminal region of the purified protein revealed the amino acid sequence IISPPVCGNELLEVGEECDCGTPENCQNECCDA, which showed identity with other snake venom metalloproteinases (SVMPs). BaltDC was devoid of proteolytic, hemorrhagic, defibrinating or coagulant activities, but it showed a specific inhibitory effect on platelet aggregation induced by ristocetin and epinephrine in PRP. IR analysis spectra strongly suggests that PO 3 2- groups, present in BaltDC, form hydrogen bonds with the PO 2 - groups present in the non-lipid portion of the membrane platelets. BaltDC may be of medical interest since it was able to inhibit platelet aggregation.

Estudio por emisión acústica del comportamiento a flexión de recubrimientos WC-Co obtenidos por plasma atmosférico

Directory of Open Access Journals (Sweden)

Segovia, F.

2007-12-01

Full Text Available Plasma sprayed cermet coatings WC-Co are used in a wide range of industrial applications, mainly due to their wear resistance even in corrosive environments. The objective of this work is to analyze mechanical response of hard metal coatings by means of three- and four-points bend tests applying acoustic emission technique to determine failure critical strength. It has been observed the effect of supported charge level in structural damage by means of optical microscopy and scanning electron microscopy. Acoustic emission has allowed us to relate damage level to stresses level and then to understand coatings failure mechanism.

Los recubrimientos de cermet WC-Co proyectados por plasma se utilizan en un amplio rango de aplicaciones industriales, principalmente por su resistencia al desgaste, incluso en medio corrosivo. El objetivo de este trabajo es analizar la respuesta mecánica de los recubrimientos de metal duro mediante ensayos de flexión a 3 y 4 puntos aplicando el método de emisión acústica para determinar las tensiones críticas de fallo. Se ha observado el efecto del nivel de carga soportado en el dañado estructural mediante microscopia óptica y electrónica de barrido. La emisión acústica ha permitido relacionar el grado de dañado con el nivel de tensiones y, así, entender el mecanismo de fallo de los recubrimientos.

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

OpenAIRE

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

2017-01-01

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

Effect of Si on DC arc plasma generation from Al-Cr and Al-Cr-Si cathodes used in oxygen

Science.gov (United States)

Zhirkov, I.; Landälv, L.; Göthelid, E.; Ahlgren, M.; Eklund, P.; Rosen, J.

2017-02-01

Al2O3 alloyed with Cr is an important material for the tooling industry. It can be synthesized from an arc discharge using Al-Cr cathodes in an oxygen atmosphere. Due to formation of Al-rich oxide islands on the cathode surface, the arc process stability is highly sensitive to oxygen pressure. For improved stability, the use of Al0.70Cr0.25Si0.05 cathodes has previously been suggested, where Si may reduce island formation. Here, we have investigated the effect of Si by comparing plasma generation and thin film deposition from Al0.7Cr0.3 and Al0.7Cr0.25Si0.05 cathodes. Plasma ion composition, ion energies, ion charge states, neutral species, droplet formation, and film composition have been characterized at different O2 flow rates for arc currents of 60 and 90 A. Si and related compounds are detected in plasma ions and in plasma neutrals. Scanning electron microscopy and energy dispersive X-ray analysis show that the cathode composition and the film composition are the same, with Si present in droplets as well. The effect of Si on the process stability, ion energies, and ion charge states is found to be negligible compared to that of the arc current. The latter is identified as the most relevant parameter for tuning the properties of the reactive discharge. The present work increases the fundamental understanding of plasma generation in a reactive atmosphere, and provides input for the choice of cathode composition and process parameters in reactive DC arc synthesis.

Redução da hidrofilicidade de filmes biodegradáveis à base de amido por meio de polimerização por plasma Reduction of hydrophilicity of biodegradable starch-based films by plasma polymerization

Directory of Open Access Journals (Sweden)

Rossana M. S. M. Thiré

2004-03-01

Full Text Available Devido ao baixo custo de produção e excelente biodegradabilidade, o amido constitui-se em matéria-prima promissora para a produção de plásticos biodegradáveis. No entanto, a grande hidrofilicidade dos filmes à base de amido representa uma séria limitação tecnológica à sua comercialização, uma vez que as propriedades dos filmes são afetadas pela variação da umidade relativa do ar durante a sua estocagem ou o seu uso. Neste trabalho, filmes de amido termoplástico foram recobertos com uma fina camada protetora polimérica gerada por intermédio da tecnologia de plasma frio. 1-Buteno e 1,3-butadieno foram utilizados como monômeros para a polimerização por plasma. Os filmes recobertos apresentaram uma redução de até 80% na absorção de água e aumento do ângulo de contato em relação à água. Estes resultados indicaram uma redução significativa na natureza hidrofílica do material à base de amido após o recobrimento.Due to low cost and excellent biodegradability, the use of starch as a raw material for bioplastic production is growing in interest. However, the properties of starch-based materials are affected by relative humidity during their use and storage due to their hydrophilic character. In this work, thermoplastic cornstarch films were coated by cold plasma technology with a protective thin layer in order to reduce water sensitivity. 1-Butene and 1,3-butadiene were used as monomers for plasma polymerization. Coated films presented a reduction of water absorption up to 80% an increase in contact angle related to water. These results indicated that the coating process reduced significantly the hydrophilic nature of the starch-based materials.

Five-Level Active-Neutral-Point-Clamped DC/DC Converter for Medium-Voltage DC Grids

DEFF Research Database (Denmark)

Liu, Dong; Deng, Fujin; Chen, Zhe

2017-01-01

This paper proposes a five-level active-neutralpoint- clamped (5L-ANPC) dc/dc converter for applications in medium voltage dc (MVDC) grids. A modulation strategy is proposed for the 5L-ANPC dc/dc converter to generate multilevel voltage waveforms, which can effectively reduce voltage change rate dv...... effectively eliminate high voltage leaps caused by the dead time effect. In addition, a capacitor voltage control strategy is proposed for the 5L-ANPC dc/dc converter to ensure the balanced flying capacitor voltage and desired five-level voltage waveforms. Finally, simulation and experimental studies...

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

DEFF Research Database (Denmark)

Deng, Fujin; Chen, Zhe

2013-01-01

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

Pulsed, atmospheric pressure plasma source for emission spectrometry

Science.gov (United States)

Duan, Yixiang; Jin, Zhe; Su, Yongxuan

2004-05-11

A low-power, plasma source-based, portable molecular light emission generator/detector employing an atmospheric pressure pulsed-plasma for molecular fragmentation and excitation is described. The average power required for the operation of the plasma is between 0.02 W and 5 W. The features of the optical emission spectra obtained with the pulsed plasma source are significantly different from those obtained with direct current (dc) discharge higher power; for example, strong CH emission at 431.2 nm which is only weakly observed with dc plasma sources was observed, and the intense CN emission observed at 383-388 nm using dc plasma sources was weak in most cases. Strong CN emission was only observed using the present apparatus when compounds containing nitrogen, such as aniline were employed as samples. The present apparatus detects dimethylsulfoxide at 200 ppb using helium as the plasma gas by observing the emission band of the CH radical. When coupled with a gas chromatograph for separating components present in a sample to be analyzed, the present invention provides an apparatus for detecting the arrival of a particular component in the sample at the end of the chromatographic column and the identity thereof.

Studies on the Electrical Characteristics of a DC Glow Discharge by Using Langmuir Probe

International Nuclear Information System (INIS)

Safaai, S. S.; Yap, S. L.; Wong, C. S.; Muniandy, S. V.; Smith, P. W.

2010-01-01

Electrical characteristics of a DC glow discharge are studied with the aim of determining the suitable parameters for stable operation of the dusty plasma system. The presence of dust particles in plasma significantly alters the charged particle equilibrium in the plasma and leads to various phenomena. Argon plasma produced by DC glow discharge is investigated with a further goal of studying dusty plasma phenomena. The discharge system has two disc-shaped parallel plate electrodes. The electrodes are enclosed in a large cylindrical stainless steel chamber filled with argon gas. Two important physical parameters affecting the condition of the discharge are the gas pressure and the inter-electrode distance. A single Langmuir probe based on the Keithley source meter is used to determine the electron temperature of the positive column. A custom designed probe is employed to determine the potential distribution between the electrodes during the discharge. The I-V characteristic curve and the Langmuir probe measurement are then used to determine the electron energy distribution of the glow discharge plasma.

IGBT Based DC/DC Converter

Directory of Open Access Journals (Sweden)

M. Akherraz

1997-12-01

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

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

DEFF Research Database (Denmark)

Ouyang, Ziwei; Andersen, Michael A. E.

2014-01-01

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

Three new DC-to-DC Single-Switch Converters

Directory of Open Access Journals (Sweden)

Barry W. Williams

2017-06-01

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

Fabrication of a Spherical Titanium Powder by Combined Combustion Synthesis and DC Plasma Treatment

Directory of Open Access Journals (Sweden)

Choi S.H.

2017-06-01

Full Text Available Combustion synthesis is capable of producing many types of refractory and ceramic materials, as well as metals, with a relatively lower cost and shorter time frame than other solid state synthetic techniques. TiO2 with Mg as reductant were dry mixed and hand compacted into a 60 mm diameter mold and then combusted under an Ar atmosphere. Depending on the reaction parameters (Mg concentration 2 ≤ α ≤ 4, the thermocouples registered temperatures between 1160°C and 1710°C · 3 mol of Mg gave the optimum results with combustion temperature (Tc and combustion velocity (Uc values of 1372°C and 0.26 cm/s respectively. Furthermore, this ratio also had the lowest oxygen concentration in this study (0.8 wt%. After combustion, DC plasma treatment was carried out to spheroidize the Ti powder for use in 3D printing. The characterization of the final product was performed using X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, and N/O analysis.

Electron cyclotron wave absorption by the fast tail generated by the dc electric field in tokamak plasmas

International Nuclear Information System (INIS)

Giruzzi, G.; Krivenski, V.; Fidone, I.; Ziebell, L.F.

1985-03-01

Wave damping near the electron gyrofrequency in a tokamak plasma with the energetic tail generated by the dc electric field is investigated. The electron tail is computed by a Fokker-Planck initial value code as a function of the relevant parameter Esub(parallel)/Esub(c)=Esub(parallel)Tsub(e)/(2πsub(e)c 3 Λ). It is shown that in most cases of physical interest strong damping of the e-mode occurs for oblique propagation. The results are of relevance for studies of ECRH in present-day tokamaks and in future reactors where a mildly relativistic electron tail is naturally present for large tsub(e). Special emphasis is therefore given to wave absorption for frequencies f significantly below the central electron gyrofrequency, and to the associated rf-driven current

Carbon nanowalls synthesis by means of atmospheric dcPECVD method

International Nuclear Information System (INIS)

Mesko, Marcel; Kotrusz, Peter; Skakalova, Viera; Vretenar, Viliam; Hulman, Martin; Soltys, Jan

2012-01-01

Carbon nanowalls (CNWs) were grown by atmospheric dc plasma enhanced chemical vapour deposition method. Maintaining plasma at atmospheric pressure give us possibility to synthetize CNWs at high rate. By using two different liquid carbon sources we can control CNWs density. Growth of sparsely distributed CNWs can be achieved by using ethanol, while hexane gives densely packed CNWs films. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Nonlinear nonresonant forces by radio-frequency waves in plasmas

International Nuclear Information System (INIS)

Gao Zhe; Fisch, Nathaniel J.; Qin, Hong; Myra, J. R.

2007-01-01

Nonresonant forces by applied rf waves in plasmas are analyzed. Along the background dc magnetic field, the force arises from the gradient of the ponderomotive potential. Only when the dc magnetic field is straight, however, is this parallel force completely consistent with that from the single particle picture, where the ponderomotive force depends on the gradients of rf fields only. Across the dc magnetic field, besides the ponderomotive force from the particle picture, additional Reynolds stress and polarization stress contribute to the total force. For waves with frequency much lower than the cyclotron frequency, the perpendicular forces from the particle and fluid pictures can have opposite signs. In plasmas with a symmetry angle (e.g., toroidal systems), nonresonant forces cannot drive net flow or current in the flux surface, but the radial force may influence macroscopic behavior of plasma. Moreover, nonresonant forces may drive flow or current in linear plasmas or in a localized region of toroidal plasmas

DC Langmuir Probe for Measurement of Space Plasma: A Brief Review

Directory of Open Access Journals (Sweden)

Koichiro Oyama

2015-09-01

Full Text Available Herein, we discuss the in situ measurement of the electron temperature in the ionosphere/plasmasphere by means of DC Langmuir probes. Major instruments which have been reported are a conventional DC Langmuir probe, whose probe voltage is swept; a pulsed probe, which uses pulsed bias voltage; a rectification probe, which uses sinusoidal signal; and a resonance cone probe, which uses radio wave propagation. The content reviews past observations made with the instruments above. We also discuss technical factors that should be taken into account for reliable measurement, such as problems related to the contamination of electrodes and the satellite surface. Finally, we discuss research topics to be studied in the near future.

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

International Nuclear Information System (INIS)

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

2010-01-01

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

75 FR 60602 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-15, DC...

Science.gov (United States)

2010-10-01

... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 10-10, DC-10-10F, DC-10-15, DC-10-30, DC-10... adding the following new AD: 2010-20-14 McDonnell Douglas Corporation: Amendment 39-16449. Docket No. FAA... the airplanes identified in paragraphs (c)(1) and (c)(2) of this AD. (1) McDonnell Douglas Corporation...

75 FR 38943 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-30, DC...

Science.gov (United States)

2010-07-07

...-0672; Directorate Identifier 2010-NM-047-AD] RIN 2120-AA64 Airworthiness Directives; McDonnell Douglas...: McDonnell Douglas Corporation: Docket No. FAA-2010-0672; Directorate Identifier 2010-NM-047-AD. Comments Due... applies to McDonnell Douglas Corporation Model DC- 10-10, DC-10-10F, DC-10-30, DC-10-30F (KDC-10), DC-10...

Caracterização por FT-IR da superfície de borracha EPDM tratada via plasma por micro-ondas

Directory of Open Access Journals (Sweden)

Renata P. dos Santos

2012-01-01

Full Text Available A superfície de uma borracha de etileno-propileno-dieno (EPDM vulcanizada foi modificada via plasma por microondas, com gases Ar, Ar/O2, N2/O2 e N2/H2, tendo como objetivo melhorar as propriedades adesivas da superfície. A técnica FT-IR/UATR foi escolhida para caracterizar as superfícies após tratamento, pois apresentou menor interferência dos ingredientes da formulação da EPDM, dentre as técnicas analisadas (ATR/KRS-5 e Ge. Grupos oxigenados foram inseridos na superfície da amostra tratada, mesmo quando não foi utilizado o oxigênio, pois estes grupos foram formados quando a superfície ativada foi exposta à atmosfera. Já em tratamentos contendo N2, grupos oxigenados e possíveis grupos nitrogenados foram identificados por FT-IR. Redução nos valores do ângulo de contato, aumento no trabalho de adesão e aumento no ensaio de resistência ao descascamento (EPDM × Poliuretano foram observados após tratamento com Ar e N2/H2, resultando em melhora nas propriedades adesivas da superfície tratada.

Electric field measurements on plasma bullets in N2 using four-wave mixing

NARCIS (Netherlands)

van der Schans, M.; Böhm, P.; Nijdam, S.; IJzerman, W.L.; Czarnetzki, U.

2015-01-01

Atmospheric pressure plasma jets driven by pulsed DC or kHz AC voltages typically consist of discrete guided ionisation waves called plasma bullets. In this work, the electric field of plasma bullets generated in a pulsed DC jet with N2 as feed gas is investigated. Electric field measurements in N2

Discharge Characteristic of VHF-DC Superimposed Magnetron Sputtering System

Science.gov (United States)

Toyoda, Hirotaka; Fukuoka, Yushi; Fukui, Takashi; Takada, Noriharu; Sasai, Kensuke

2014-10-01

Magnetron plasmas are one of the most important tools for sputter deposition of thin films. However, energetic particles from the sputtered target such as backscattered rare gas atoms or oxygen negative ions from oxide targets sometimes induce physical and chemical damages as well as surface roughening to the deposited film surface during the sputtering processes. To suppress kinetic energy of such particles, superposition of RF or VHF power to the DC power has been investigated. In this study, influence of the VHF power superposition on the DC target voltage, which is important factor to determine kinetic energy of high energy particles, is investigated. In the study, 40 MHz VHF power was superimposed to an ITO target and decrease in the target DC voltage was measured as well as deposited film deposition properties such as deposition rate or electrical conductivity. From systematic measurement of the target voltage, it was revealed that the target voltage can be determined by a very simple parameter, i.e., a ratio of VHF power to the total input power (DC and VHF powers) in spite of the DC discharge current. Part of this work was supported by ASTEP, JST.

75 FR 6160 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-15, DC...

Science.gov (United States)

2010-02-08

...-0032; Directorate Identifier 2009-NM-213-AD] RIN 2120-AA64 Airworthiness Directives; McDonnell Douglas...: McDonnell Douglas Corporation: Docket No. FAA-2010-0032; Directorate Identifier 2009-NM-213-AD. Comments Due... applies to McDonnell Douglas Corporation Model DC- 10-10, DC-10-10F, DC-10-15, DC-10-30, DC-10-30F (KC-10A...

Chromatic monitoring of dc plasma torches: The latest developments

Czech Academy of Sciences Publication Activity Database

Djakov, B. E.; Enikov, R.; Oliver, D.H.; Hrabovský, Milan; Kopecký, Vladimír

2006-01-01

Roč. 3, č. 2 (2006), s. 170-173 ISSN 1612-8850 R&D Projects: GA ČR(CZ) GA202/05/0669 Institutional research plan: CEZ:AV0Z20430508 Keywords : chromatic monitoring * on-line control * plasma jet * plasma torch * powder Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.298, year: 2006

El factor de constreñimiento y su dependencia de las dimensiones en probetas de fractura DC(T

Directory of Open Access Journals (Sweden)

Donoso, J. R.

2002-10-01

Full Text Available The Common Format Equation constraint factor, Ω*, introduced by Donoso and Landes, is analyzed in terms of its dependence on crack length and thickness, in disk-shaped compact specimens, DC(T. Numerical analysis of the load-displacement behavior of blunt-notched DC(T specimens, and experimental evaluation of pre-cracked DC(T specimens of various thickness, allows one to obtain the values of Ω* in terms of the thickness-to-ligament ratio, B/b, as a measure of the degree of size-induced constraint in this geometry.

El factor de constreñimiento de la Ecuación del Formato Común, Ω*, desarrollado por Donoso y Landes, se analiza en términos de su dependencia de la longitud de grieta y el espesor, en probetas de geometría disco-compacta, DC(T. El análisis numérico del comportamiento carga-desplazamiento de probetas DC(T, con entalla roma, y la evaluación experimental de probetas DC(T prefisuradas, con diferentes espesores, permite obtener los valores de Ω*, en función del cociente espesor/ligamento, B/b, como una medida del grado de constreñimiento inducido por la relación de tamaños en esta geometría.

Low Pressure DC Glow Discharge Air Plasma Surface Treatment of Polyethylene (PE) Film for Improvement of Adhesive Properties

International Nuclear Information System (INIS)

Pandiyaraj, Krishnasamy Navaneetha; Yoganand, Paramasivam; Selvarajan, Vengatasamy; Deshmukh, Rajendrasing R.; Balasubramanian, Suresh; Maruthamuthu, Sundaram

2013-01-01

The present work deals with the change in surface properties of polyethylene (PE) film using DC low pressure glow discharge air plasma and makes it useful for technical applications. The change in hydrophilicity of the modified PE film surface was investigated by measuring contact angle and surface energy as a function of exposure time. Changes in the morphological and chemical composition of PE films were analyzed by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The improvement in adhesion was studied by measuring T-peel and lap-shear strength. The results show that the wettability and surface energy of the PE film has been improved due to the introduction of oxygen-containing polar groups and an increase in surface roughness. The XPS result clearly shows the increase in concentration of oxygen content and the formation of polar groups on the polymer surface. The AFM observation on PE film shows that the roughness of the surface increased due to plasma treatment. The above morphological and chemical changes enhanced the adhesive properties of the PE film surfaces, which was confirmed by T-peel and lap-shear tests.

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

Science.gov (United States)

2010-10-07

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

Plasma spheroidization of nickel powders in a plasma reactor

Indian Academy of Sciences (India)

Unknown

and size of the particles are among critical parameters ... shape components, which helps to conserve scarce raw materials. There are several methods of producing rapidly solidi- ... spherical nickel powders using the d.c. plasma reactor is.

Multi Bus DC-DC Converter in Electric Hybrid Vehicles

Science.gov (United States)

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

2018-04-01

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

Step-Up DC-DC Power Converter

DEFF Research Database (Denmark)

2015-01-01

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

AC-DC PFC Converter Using Combination of Flyback Converter and Full-bridge DC-DC Converter

Directory of Open Access Journals (Sweden)

Moh. Zaenal Efendi

2014-06-01

Full Text Available This paper presents a combination of power factor correction converter using Flyback converter and Full-bridge dc-dc converter in series connection. Flyback converter is operated in discontinuous conduction mode so that it can serve as a power factor correction converter and meanwhile Full-bridge dc-dc converter is used for dc regulator. This converter system is designed to produce a 86 Volt of output voltage and 2 A of output current. Both simulation and experiment results show that the power factor of this converter achieves up to 0.99 and meets harmonic standard of IEC61000-3-2. Keywords: Flyback Converter, Full-bridge DC-DC Converter, Power Factor Correction.

Early Oscillation Detection for DC/DC Converter Fault Diagnosis

Science.gov (United States)

Wang, Bright L.

2011-01-01

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

The experience with JET's combined dc/Rf glow discharge cleaning (GDC) system

International Nuclear Information System (INIS)

Pearce, R.J.H.; Andrew, P.; Bryan, S.

1996-01-01

The JET Tokamak was fitted with four new electrodes of novel design, each powered from individual computer controlled dc and RF supplies. Details of enhancements and problems from 15 months experience with the system are outlined. Experiments were performed to assess the effect of RF on the glow discharge characteristics, and to establish stable glow at low pressure and high voltage. JET combined RF/dc glow discharge cleaning (GDC) had no significant advantages over pure dc GDC, provided highly stable dc current control was obtained. In fact, the mechanically weak electrode inductor spiral required to allow RF posed a distinct disadvantage. The electrodes were converted to simple plates, following damage caused by halo currents during Tokamak plasma disruptions. The performance of these electrodes was assessed. Future developments in the JET GDC system are outlined. (Author)

Use of dc Ar microdischarge with nonlocal plasma for identification of metal samples

Energy Technology Data Exchange (ETDEWEB)

Kudryavtsev, A. A., E-mail: akud@ak2138.spb.edu [St. Petersburg State University, 7-9 Universitetskaya nab., 199034 St. Petersburg (Russian Federation); Stefanova, M. S.; Pramatarov, P. M. [Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Blvd., 1784 Sofia (Bulgaria)

2015-04-07

The possibility of using the collisional electron spectroscopy (CES) method for the detection of atoms from metal samples is experimentally verified. The detection and identification of metal atoms from a Pt sample in the nonlocal plasma of short (without positive column) dc Ar microdischarge at intermediate pressures (5–30 Torr) is realized in this work. Cathode sputtering is used for atomization of the metal under analysis. The identification of the analyzed metal is made from the energy spectra of groups of fast nonlocal electrons—characteristic electrons released in the Penning ionization of the Pt atoms by Ar metastable atoms and molecules. The acquisition of the electron energy spectra is performed using an additional electrode—a sensor located at the boundary of the discharge volume. The Pt characteristic Penning electrons form the maxima in the electron energy spectra at the energies of their appearance, which are 2.6 eV and 1.4 eV. From the measured energy of the maxima, identification of the metal atoms is accomplished. The characteristic Ar maxima due to pair collisions between Ar metastable atoms and molecules and super-elastic collisions are also recorded. This study demonstrates the possibility of creating a novel microplasma analyzer for atoms from metal samples.

Superconducting energy stabilizer with charging and discharging DC-DC converters

International Nuclear Information System (INIS)

Kim, S.H.; Kostecki, E.L.; DeWinkel, C.C.

1992-01-01

This patent describes a superconducting energy stabilizer having multiple load connections and employing DC-DC conversion for storing energy in a superconducting inductive energy storage device having a first end and a second end, and for releasing the stored energy from the superconducting inductive energy storage device to a load or loads or to a utility or an industrial electrical distribution system, the superconducting energy stabilizer having multiple load connections and employing DC-DC conversion. It comprises: energy storage cell means for supplying energy to the load, discharging DC-DC converter means for releasing energy from the superconducting inductive energy storage device to the energy storage cell means, the discharging DC-DC converter means having input terminals, output terminals, and a discharging control line means for carrying signals controlling the operation of the discharging DC-DC converter means, one of the input terminals of the discharging DC-DC converter means coupled to the first end of the superconducting energy storage device

dc Arc Fault Effect on Hybrid ac/dc Microgrid

Science.gov (United States)

Fatima, Zahra

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

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

International Nuclear Information System (INIS)

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

2004-01-01

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

Plasma spot welding of ferritic stainless steels

Directory of Open Access Journals (Sweden)

Lešnjak, A.

2002-06-01

Full Text Available Plasma spot welding of ferritic stainless steels is studied. The study was focused on welding parameters, plasma and shielding gases and the optimum welding equipment. Plasma-spot welded overlap joints on a 0.8 mm thick ferritic stainless steel sheet were subjected to a visual examination and mechanical testing in terms of tension-shear strength. Several macro specimens were prepared. Plasma spot welding is suitable to use the same gas as shielding gas and as plasma gas, i.e., a 98 % Ar/2 % H ₂ gas mixture. Tension-shear strength of plasma-spot welded joints was compared to that of resistance-spot welded joints. It was found that the resistance welded joints withstand a somewhat stronger load than the plasma welded joints due to a larger weld spot diameter of the former. Strength of both types of welded joints is approximately the same.

El artículo describe el proceso de soldeo de aceros inoxidables ferríticos por puntos con plasma. La investigación se centró en el establecimiento de los parámetros óptimos de la soldadura, la definición del gas de plasma y de protección más adecuado, así como del equipo óptimo para la realización de la soldadura. Las uniones de láminas de aceros inoxidables ferríticos de 0,8 mm de espesor, soldadas a solape por puntos con plasma, se inspeccionaron visualmente y se ensayaron mecánicamente mediante el ensayo de cizalladura por tracción. Se realizaron macro pulidos. Los resultados de la investigación demostraron que la solución más adecuada para el soldeo por puntos con plasma es elegir el mismo gas de plasma que de protección. Es decir, una mezcla de 98 % de argón y 2 % de hidrógeno. La resistencia a la cizalladura por tracción de las uniones soldadas por puntos con plasma fue comparada con la resistencia de las uniones soldadas por resistencia por puntos. Se llegó a la conclusión de que las uniones soldadas por resistencia soportan una carga algo mayor que la uniones

Milliwatt dc/dc Inverter

Science.gov (United States)

Mclyman, C. W.

1983-01-01

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

75 FR 63040 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-30, DC...

Science.gov (United States)

2010-10-14

... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 10-10, DC-10-10F, DC-10-30, DC-10-30F (KDC-10... following new airworthiness directive (AD): 2010-21-13 McDonnell Douglas Corporation: Amendment 39-16473... November 18, 2010. Affected ADs (b) None. Applicability (c) This AD applies to McDonnell Douglas...

75 FR 68246 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-15, DC...

Science.gov (United States)

2010-11-05

...-1044; Directorate Identifier 2010-NM-033-AD] RIN 2120-AA64 Airworthiness Directives; McDonnell Douglas..., 2007) and adding the following new AD: McDonnell Douglas Corporation: Docket No. FAA-2010-1044.... Applicability (c) This AD applies to all McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-15, DC...

Overview of Multi-DC-Bus Solutions for DC Microgrids

DEFF Research Database (Denmark)

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

2013-01-01

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

Design of resonant converter based DC power supply for RF amplifier

International Nuclear Information System (INIS)

Mohan, Kartik; Suthar, Gajendra; Dalicha, Hrushikesh; Agarwal, Rohit; Trivedi, R.G.; Mukherjee, Aparajita

2017-01-01

ITER require 20 MW of RF power to a large variety of plasmas in the Ion Cyclotron frequency range for heating and driving plasma current. Nine RF sources of 2.5MW RF power level each collectively will accomplish the above requirement. Each RF source consists of SSPA, driver and end stage, above which driver and end stage amplifier are tube (Tetrode/Diacrode) based which requires auxiliary DC power source viz. filament, screen grid and control grid DC power supply. DC power supply has some stringent requirements like low stored energy, fast turn off, and low ripple value, etc. This paper will focus only on Zero Current Switching (ZCS) resonant converter based buck converter. This can serve the purpose of control grid and screen grid DC power supply for above requirement. IGBT switch will be used at 20 kHz so as to lower the filter requirement hence low stored energy and ripple in the output voltage. ZCS operation will also assist us in reducing EMI/EMC effect. Design of resonant tank circuit is important aspect of the converter as it forms the backbone of the complete system and basis of selection of other important parameters as well hence mathematical model analysis with the help of circuit equations for various modes have been shown as a part of selection criteria. Peak current through the switch, duty cycle, switching frequency will be the design parameters for selecting resonant tank circuit

DC to DC power converters and methods of controlling the same

Science.gov (United States)

Steigerwald, Robert Louis; Elasser, Ahmed; Sabate, Juan Antonio; Todorovic, Maja Harfman; Agamy, Mohammed

2012-12-11

A power generation system configured to provide direct current (DC) power to a DC link is described. The system includes a first power generation unit configured to output DC power. The system also includes a first DC to DC converter comprising an input section and an output section. The output section of the first DC to DC converter is coupled in series with the first power generation unit. The first DC to DC converter is configured to process a first portion of the DC power output by the first power generation unit and to provide an unprocessed second portion of the DC power output of the first power generation unit to the output section.

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

International Nuclear Information System (INIS)

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

2012-01-01

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

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

Directory of Open Access Journals (Sweden)

R. Silva-Ortigoza

2014-01-01

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

Estudos de esterilização por plasma a pressão atmosférica

OpenAIRE

Souza, João Henrique Campos de

2013-01-01

Apesar da variedade de tecnologias disponíveis aos serviços de saúde paia o processamento dos produtos para a saúde, as especificidades de cada instrumental são determinantes na escolha do método mais indicado. Atualmente, o desafio da área tecnológica é desenvolver métodos eficazes para o processamento de materiais que não podem ser submetidos a grandes estresses físicos, como temperatura e pressão. A esterilização por plasma é uma tecnologia que chama muito a atenção pela rapidez, segurança...

Strict calculation of electron energy distribution functions in inhomogeneous plasmas

International Nuclear Information System (INIS)

Winkler, R.

1996-01-01

It is objective of the paper to report on strict calculations of the velocity or energy distribution function function and related macroscopic properties of the electrons from appropriate electron kinetic equations under various plasma conditions and to contribute to a better understanding of the electron behaviour in inhomogeneous plasma regions. In particular, the spatial relaxation of plasma electrons acted upon by uniform electric fields, the response of plasma electrons on spatial disturbances of the electric field, the electron kinetics under the impact of space charge field confinement in the dc column plasma and the electron velocity distribution is stronger field as occurring in the electrode regions of a dc glow discharge is considered. (author)

Development of a dc, broad beam, Mevva ion source

International Nuclear Information System (INIS)

Brown, I.G.; Dickinson, M.R.; Galvin, J.E.; MacGill, R.A.

1991-09-01

We are developing an embodiment of metal vapor vacuum arc (Mevva) ion source which will operate dc and have very large area beam. In preliminary testing, a dc titanium ion beam was formed with a current of approximately 0.6 amperes at an extraction voltage of 9kV (about 18 keV ion energy, by virtue of the ion charge state distribution) and using an 18 cm diameter set of multi-aperture. Separately, we have tested and formed beam from a 50 cm diameter (2000 cm 2 ) set of grids using a pulsed plasma gun. This configuration appears to be very efficient in terms of plasma utilization, and we have formed beams with diameter 33 cm (FWHM) and ion current up to 7 amperes at an extraction voltage of 50 kV (about 100 keV mean ion energy) and up to 20 amperes peak at the current overshoot part of the beam pulse. Here we describe this Part Of our Mevva development program and summarize the results obtained to-date

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

OpenAIRE

Liwen Pan; Chengning Zhang

2016-01-01

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

PENGGUNAAN FUZZY LOGIC UNTUK KONTROL PARALLEL CONVERTER DC-DC

Directory of Open Access Journals (Sweden)

Bambang Prio Hartono

2012-09-01

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

Laser optically pumped by laser-produced plasma

International Nuclear Information System (INIS)

Silfvast, W.T.; Wood, O.R. II.

1975-01-01

Laser solids, liquids and gases are pumped by a new technique in which the output from an efficient molecular laser, such as a CO 2 laser, ionizes a medium, such as xenon, into a generally cylindrical plasma volume, in proximity to the pumped laser body. Breakdown yields a visible and ultraviolet-radiation-emitting plasma in that volume to pump the laser body. The spectral radiance of the plasma is significantly higher than that produced by a dc-discharge-heated plasma at nearly all wavelengths in the plasma spectrum. The risetime of radiation from the laser-produced plasma can also be significantly shorter than that of a dc heated plasma. A further advantage resides in the fact that in some applications the attenuating walls needed by flashlamps may be eliminated with the result that laser threshold is more readily reached. Traveling wave excitation may be provided by oblique incidence of the pumping laser beam through the ionizable medium to create sequential ionization of portions of that medium along the length of the pumped laser body. (auth)

Full range ZVS DC-DC converter

International Nuclear Information System (INIS)

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

2011-01-01

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

AC/DC/pulsed-power modulator for corona-plasma generation

NARCIS (Netherlands)

Ariaans, T.H.P.; Pemen, A.J.M.; Winands, G.J.J.; Heesch, van E.J.M.; Liu, Z.

2009-01-01

Gas-cleaning techniques using nonthermal plasma are slowly introduced into industry nowadays. In this paper, we present a novel power modulator for the efficient generation of large-volume corona plasma. No expensive high-voltage components are required. Switching is done at an intermediate voltage

TOPOLOGICAL REVIEW AND ANALYSIS OF DC-DC BOOST CONVERTERS

Directory of Open Access Journals (Sweden)

V. INDRA GANDHI

2017-06-01

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

Novel non-equilibrium modelling of a DC electric arc in argon

Science.gov (United States)

Baeva, M.; Benilov, M. S.; Almeida, N. A.; Uhrlandt, D.

2016-06-01

A novel non-equilibrium model has been developed to describe the interplay of heat and mass transfer and electric and magnetic fields in a DC electric arc. A complete diffusion treatment of particle fluxes, a generalized form of Ohm’s law, and numerical matching of the arc plasma with the space-charge sheaths adjacent to the electrodes are applied to analyze in detail the plasma parameters and the phenomena occurring in the plasma column and the near-electrode regions of a DC arc generated in atmospheric pressure argon for current levels from 20 A up to 200 A. Results comprising electric field and potential, current density, heating of the electrodes, and effects of thermal and chemical non-equilibrium are presented and discussed. The current-voltage characteristic obtained is in fair agreement with known experimental data. It indicates a minimum for arc current of about 80 A. For all current levels, a field reversal in front of the anode accompanied by a voltage drop of (0.7-2.6) V is observed. Another field reversal is observed near the cathode for arc currents below 80 A.

Novel non-equilibrium modelling of a DC electric arc in argon

International Nuclear Information System (INIS)

Baeva, M; Uhrlandt, D; Benilov, M S; Almeida, N A

2016-01-01

A novel non-equilibrium model has been developed to describe the interplay of heat and mass transfer and electric and magnetic fields in a DC electric arc. A complete diffusion treatment of particle fluxes, a generalized form of Ohm’s law, and numerical matching of the arc plasma with the space-charge sheaths adjacent to the electrodes are applied to analyze in detail the plasma parameters and the phenomena occurring in the plasma column and the near-electrode regions of a DC arc generated in atmospheric pressure argon for current levels from 20 A up to 200 A. Results comprising electric field and potential, current density, heating of the electrodes, and effects of thermal and chemical non-equilibrium are presented and discussed. The current–voltage characteristic obtained is in fair agreement with known experimental data. It indicates a minimum for arc current of about 80 A. For all current levels, a field reversal in front of the anode accompanied by a voltage drop of (0.7–2.6) V is observed. Another field reversal is observed near the cathode for arc currents below 80 A. (paper)

Surface modification of polyethylene by plasma; Modificacion superficial de polietileno por plasma

Energy Technology Data Exchange (ETDEWEB)

Colin O, E

2003-07-01

The products made of polyethylene (PE) go from construction materials, electric insulating until packing material. The films for bags and pack occupy 83.6% of the distribution of the market of PE approximately. The enormous quantity of PE that is generated by its indiscriminate use brings as consequence a deterioration to the atmosphere, due to the long life that they present as waste. This work is a study on the modification of low density polyethylene films. In this type of thin materials, the changes in the surface meet with largely on the conformation of the rest of the material. To induce changes that modify the surface of PE, plasmas were used with reactive atmospheres of air, oxygen and nitrogen. The experimentation that was carries out went to introduce the PE to a cylindrical reactor where it was generated the plasma of air, oxygen and nitrogen to different times of exposure. After having carried out the exposure to the plasma, it was found that in the polyethylene it modifies their morphology, crystallinity, hydrophobicity, composition and electric conductivity. The analytical techniques that were used to characterize later to the polyethylene of being in contact with the plasma were: X-ray diffraction, Scanning Electron Microscopy, Infrared spectroscopy, Electric conductivity, Angle of contact and finally Thermal Gravimetric Analysis. The content of this work it is presented in five chapters: In the chapter 1 there are presented some general concepts of plasma and of the one polymer in study PE. In the chapter 2 it is made a general revision on modification of surfaces, as well as the properties that were modified in polymeric materials that were exposed to plasma in previous works. In the chapter 3 the experimental part and the conditions used are described in the modification of the PE. Also in this chapter a brief description it is made of the used characterization techniques. The results and discussion are presented in the chapter 4. These results

DC/DC converters for integration of double-layer condensers in onboard power supply; DC/DC-Wandler zur Einbindung von Doppelschichtkondensatoren in das Fahrzeugenergiebordnetz

Energy Technology Data Exchange (ETDEWEB)

Polenov, Dieter

2010-01-15

The paper discusses DC/DC converters for integration of double layer condensers into the onboard power system. First, requirements on DC/DC converters are listed and compared on the basis of three exemplary applications. A DC/DC converter concept is developed for decoupling transient high-power loads like electric steering systems. Three different topologies are compared using a specially developed method in order to find the best solution for the given application. In order to establish adequate criteria for selecting the switching frequency and inductivities of storage throttles, the influence of the trottle power change on the switching characteristics of the MOSFETs and on certain ranges of EMP interference emissions is investigated. As methods of optimising the operation of the synchronous rectifiers, parallel connection of Schottky diodes and synchronous rectifiers as well as the variation of the shut-off dead times of synchronous rectifiers were investigated. Further, a concept for converter control was developed in consideration of the intended application and topology. Finally, selected aspects for implementation of the DC/DC converter concept are presented as well as the results of experimental investigations.

Caracterización de dos brotes de fiebre tifoidea en Apartadó, Antioquia, 2005

Directory of Open Access Journals (Sweden)

Nora María Cardona-Castro

2007-06-01

Conclusiones. La electroforesis en campo pulsado estableció la presencia de dos brotes, que inicialmente, por epidemiología y pruebas fenotípicas del patógeno, habían sido descritos como uno solo. Además, permitió diferenciar dos aislamientos de origen clonal diferente, que indicaron casos aislados. No se pudo corroborar la fuente de infección en el agua.

Chaos analysis and chaotic EMI suppression of DC-DC converters

CERN Document Server

Zhang, Bo

2014-01-01

Introduces chaos theory, its analytical methods and the means to apply chaos to the switching power supply design DC-DC converters are typical switching systems which have plenty of nonlinear behaviors, such as bifurcation and chaos. The nonlinear behaviors of DC-DC converters have been studied heavily over the past 20 years, yet researchers are still unsure of the practical application of bifurcations and chaos in switching converters. The electromagnetic interference (EMI), which resulted from the high rates of changes of voltage and current, has become a major design criterion in DC-DC co

Arc generators of low-temperature plasma

International Nuclear Information System (INIS)

Krolikowski, Cz.; Niewiedzial, R.; Siwiec, J.

1979-01-01

This paper is a review of works concerning investigation and use of low-temperature plasma in arc plasma generators made in Electric Power Institute of PP. There are discussed: analytical approach to a problem of volt-current and operational characteristics of DC arc plasma generators, determination of limits of their stable work and possibilities of their use to technological aims. (author)

Full wave dc-to-dc converter using energy storage transformers

Science.gov (United States)

Moore, E. T.; Wilson, T. G.

1969-01-01

Full wave dc-to-dc converter, for an ion thrustor, uses energy storage transformers to provide a method of dc-to-dc conversion and regulation. The converter has a high degree of physical simplicity, is lightweight and has high efficiency.

Pulsewidth modulated DC-to-DC power conversion circuits, dynamics, and control designs

CERN Document Server

Choi, Byungcho

2013-01-01

This is the definitive reference for anyone involved in pulsewidth modulated DC-to-DC power conversion Pulsewidth Modulated DC-to-DC Power Conversion: Circuits, Dynamics, and Control Designs provides engineers, researchers, and students in the power electronics field with comprehensive and complete guidance to understanding pulsewidth modulated (PWM) DC-to-DC power converters. Presented in three parts, the book addresses the circuitry and operation of PWM DC-to-DC converters and their dynamic characteristics, along with in-depth discussions of control design of PWM DC-to

Streaming metal plasma generation by vacuum arc plasma guns

International Nuclear Information System (INIS)

MacGill, R.A.; Dickinson, M.R.; Anders, A.; Monteiro, O.R.; Brown, I.G.

1998-01-01

We have developed several different embodiments of repetitively pulsed vacuum arc metal plasma gun, including miniature versions, multicathode versions that can produce up to 18 different metal plasma species between which one can switch, and a compact high-duty cycle well-cooled version, as well as a larger dc gun. Plasma guns of this kind can be incorporated into a vacuum arc ion source for the production of high-energy metal ion beams, or used as a plasma source for thin film formation and for metal plasma immersion ion implantation and deposition. The source can also be viewed as a low-energy metal ion source with ion drift velocity in the range 20 - 200 eV depending on the metal species used. Here we describe the plasma sources that we have developed, the properties of the plasma generated, and summarize their performance and limitations. copyright 1998 American Institute of Physics

Effect of N{sub 2} and Ar gas on DC arc plasma generation and film composition from Ti-Al compound cathodes

Energy Technology Data Exchange (ETDEWEB)

Zhirkov, Igor, E-mail: igozh@ifm.liu.se; Rosen, Johanna [Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping (Sweden); Oks, Efim [Institute of High Current Electronics SB RAS, 2/3 Akademichesky Avenue, 634055 Tomsk (Russian Federation)

2015-06-07

DC arc plasma from Ti, Al, and Ti{sub 1−x}Al{sub x} (x = 0.16, 0.25, 0.50, and 0.70) compound cathodes has been characterized with respect to plasma chemistry (charged particles) and charge-state-resolved ion energy for Ar and N{sub 2} pressures in the range 10{sup −6} to 3 × 10{sup −2} Torr. Scanning electron microscopy was used for exploring the correlation between the cathode and film composition, which in turn was correlated with the plasma properties. In an Ar atmosphere, the plasma ion composition showed a reduction of Al of approximately 5 at. % compared to the cathode composition, while deposited films were in accordance with the cathode stoichiometry. Introducing N{sub 2} above ∼5 × 10{sup −3} Torr, lead to a reduced Al content in the plasma as well as in the film, and hence a 1:1 correlation between the cathode and film composition cannot be expected in a reactive environment. This may be explained by an influence of the reactive gas on the arc mode and type of erosion of Ti and Al rich contaminations, as well as on the plasma transport. Throughout the investigated pressure range, a higher deposition rate was obtained from cathodes with higher Al content. The origin of generated gas ions was investigated through the velocity rule, stating that the most likely ion velocities of all cathode elements from a compound cathode are equal. The results suggest that the major part of the gas ions in Ar is generated from electron impact ionization, while gas ions in a N{sub 2} atmosphere primarily originate from a nitrogen contaminated layer on the cathode surface. The presented results provide a contribution to the understanding processes of plasma generation from compound cathodes. It also allows for a more reasonable approach to the selection of composite cathode and experimental conditions for thin film depositions.

Triple voltage dc-to-dc converter and method

Science.gov (United States)

Su, Gui-Jia

2008-08-05

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

3D Numerical Analysis of the Arc Plasma Behavior in a Submerged DC Electric Arc Furnace for the Production of Fused MgO

International Nuclear Information System (INIS)

Wang Zhen; Wang Ninghui; Li Tie; Cao Yong

2012-01-01

A three dimensional steady-state magnetohydrodynamic model is developed for the arc plasma in a DC submerged electric arc furnace for the production of fused MgO. The arc is generated in a small semi-enclosed space formed by the graphite electrode, the molten bath and unmelted raw materials. The model is first used to solve a similar problem in a steel making furnace, and the calculated results are found to be in good agreement with the published measurements. The behavior of arcs with different arc lengths is also studied in the furnace for MgO production. From the distribution of the arc pressure on the bath surface it is shown that the arc plasma impingement is large enough to cause a crater-like depression on the surface of the MgO bath. The circulation of the high temperature air under the electrode may enhance the arc efficiency, especially for a shorter arc.

Numerical and experimental study on a pulsed-dc plasma jet

Science.gov (United States)

Liu, X. Y.; Pei, X. K.; Lu, X. P.; Liu, D. W.

2014-06-01

A numerical and experimental study of plasma jet propagation in a low-temperature, atmospheric-pressure, helium jet in ambient air is presented. A self-consistent, multi-species, two-dimensional axially symmetric plasma model with detailed finite-rate chemistry of helium-air mixture composition is used to provide insights into the propagation of the plasma jet. The obtained simulation results suggest that the sheath forms near the dielectric tube inner surface and shields the plasma channel from the tube surface. The strong electric field at the edge of the dielectric field enhances the ionization in the air mixing layer; therefore, the streamer head becomes ring-shaped when the streamer runs out of the tube. The avalanche-to-streamer transition is the main mechanism of streamer advancement. Penning ionization dominates the ionization reactions and increases the electrical conductivity of the plasma channel. The simulation results are supported by experimental observations under similar discharge conditions.

Switching coordination of distributed dc-dc converters for highly efficient photovoltaic power plants

Science.gov (United States)

Agamy, Mohammed; Elasser, Ahmed; Sabate, Juan Antonio; Galbraith, Anthony William; Harfman Todorovic, Maja

2014-09-09

A distributed photovoltaic (PV) power plant includes a plurality of distributed dc-dc converters. The dc-dc converters are configured to switch in coordination with one another such that at least one dc-dc converter transfers power to a common dc-bus based upon the total system power available from one or more corresponding strings of PV modules. Due to the coordinated switching of the dc-dc converters, each dc-dc converter transferring power to the common dc-bus continues to operate within its optimal efficiency range as well as to optimize the maximum power point tracking in order to increase the energy yield of the PV power plant.

Experiencias en la vigilancia epidemiológica de agentes patógenos transmitidos por alimentos a través de electroforesis en campo pulsado (PFGE en el Perú Experiences in the epidemiological surveillance of foodborne pathogens by pulsed field gel electrophoresis (PFGE in Peru

Directory of Open Access Journals (Sweden)

María Luz Zamudio

2011-03-01

Full Text Available Las enfermedades transmitidas por alimentos (ETA y otras enfermedades entéricas infecciosas ocurren a menudo como brotes y son causa de morbilidad y mortalidad en todo el mundo. En el Perú, son un importante problema de salud pública y son causados por una gran variedad de agentes infecciosos. Para la investigación epidemiológica se utiliza una variedad de métodos de tipificación. Una de las herramientas más importantes en la subtipificación molecular de patógenos bacterianos es la técnica de la electroforesis en campo pulsado (PFGE, que es un método altamente resolutivo que permite la discriminación entre diferentes aislamientos bacterianos epidemiológicamente relacionados. El Instituto Nacional de Salud (INS del Perú integra las redes WHO Global Foodborne Infections Network y la Red PulseNet América Latina y Caribe, con quienes comparte los perfiles genéticos de las cepas patógenas aisladas, permitiendo comparar los genotipos de cepas semejantes halladas en diferentes países y reconocer la ocurrencia de brotes epidémicos en la región, fortaleciendo el sistema de vigilancia epidemiológica regional y generando una rápida respuesta conjunta entre países. Se presenta la experiencia de los dos últimos años sobre los avances en la utilización de estas herramientas estratégicas que nos ha permitido caracterizar patrones de genotipo de principales patógenos implicados en ETA a partir de aislamientos recuperados de la red de laboratorios del Perú.Foodborne diseases and other enteric infections often occur as outbreaks and cause morbidity and mortality all over the world. In Perú, they represent a serious public health problem, and are caused by a great variety of infectious agents. For epidemiological research, a wide array of typification methods are used. One of the most important tools for the molecular subtyping of bacterial pathogens is the Pulsed Field Gel Electrophoresis (PFGE, which is a highly precise method that

Construction of an input sensitivity variable CAMAC module for measuring DC voltage

International Nuclear Information System (INIS)

Noda, Nobuaki.

1979-03-01

In on-line experimental data processing systems, the collection of DC voltage data is frequently required. In plasma confinement experiments, for example, the range of input voltage is very wide from over 1 kV applied to photomultiplier tubes to 10 mV full scale of the controller output for ionization vacuum gauges. A DC voltmeter CAMAC module with variable input range, convenient for plasma experiments and inexpensive, has been constructed for trial. The number of input channels is 16, and the input range is changeable in six steps from +-10 mV to +-200 V; these are all set by commands from a computer. The module is actually used for the on-line data processing system for JIPP T-2 experiment. The ideas behind its development, and the functions, features and usage of the module are described in this report. (J.P.N.)

INFLUENCIA DE LA NITRURACIÓN POR PLASMA SOBRE EL COMPORTAMIENTO A LA CORROSIÓN Y LA ADHESIÓN DE RECUBRIMIENTOS DLC SOBRE ACERO INOXIDABLE AISI 420

Directory of Open Access Journals (Sweden)

Jorge N. Pecina

2016-01-01

Full Text Available En este trabajo se estudió el comportamiento a la corrosió n y la adhesión de dos rec ubrimientos DLC (“Diamond Like Carbon ” , “Soft” y “Hard”, depositados por PACVD (“Plasma Assisted Chemical Vapour Deposition” sobre acero AISI 420, templado y revenido y /o nitrurado por plasma . Se analizaron por espectroscopía Raman y midió dureza en superficie. Se observó la microestructura por OM y SEM. Se realizaron pruebas de adhesión con indentación Rockwell C . S e practicaron ensayos de Niebla Salina e inmersión en HCl . Los DLC “ Soft ” presentaron una dureza de 5 00 HV y un espesor de 2 0 μm , mientras que los “ Hard ” tuvieron 1400 HV y 2 ,5 μm. Ambos recubrimientos presentaron bajo coeficiente de fricción y buena adhesión sobre el sustrato nitrurado . También presentaron buena resistencia a la corrosión atmosférica. En HCl el DLC retardó la degradación que se presentó rápidamente en las muestras sin recubrir.

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

OpenAIRE

Can, Erol; Sayan, Hasan Hüseyin

2017-01-01

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

On and off controlled resonant dc-dc power converter

DEFF Research Database (Denmark)

2015-01-01

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

Propagation characteristics of dust–acoustic waves in presence of a floating cylindrical object in the DC discharge plasma

International Nuclear Information System (INIS)

Choudhary, Mangilal; Mukherjee, S.; Bandyopadhyay, P.

2016-01-01

The experimental observation of the self–excited dust acoustic waves (DAWs) and its propagation characteristics in the absence and presence of a floating cylindrical object is investigated. The experiments are carried out in a direct current (DC) glow discharge dusty plasma in a background of argon gas. Dust particles are found levitated at the interface of plasma and cathode sheath region. The DAWs are spontaneously excited in the dust medium and found to propagate in the direction of ion drift (along the gravity) above a threshold discharge current at low pressure. Excitation of such a low frequency wave is a result of the ion–dust streaming instability in the dust cloud. Characteristics of the propagating dust acoustic wave get modified in the presence of a floating cylindrical object of radius larger than that of the dust Debye length. Instead of propagation in the vertical direction, the DAWs are found to propagate obliquely in the presence of the floating object (kept either vertically or horizontally). In addition, a horizontally aligned floating object forms a wave structure in the cone shaped dust cloud in the sheath region. Such changes in the propagation characteristics of DAWs are explained on the basis of modified potential (or electric field) distribution, which is a consequence of coupling of sheaths formed around the cylindrical object and the cathode.

Propagation characteristics of dust–acoustic waves in presence of a floating cylindrical object in the DC discharge plasma

Energy Technology Data Exchange (ETDEWEB)

Choudhary, Mangilal, E-mail: mangilal@ipr.res.in [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India); Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400085 (India); Mukherjee, S.; Bandyopadhyay, P. [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India)

2016-08-15

The experimental observation of the self–excited dust acoustic waves (DAWs) and its propagation characteristics in the absence and presence of a floating cylindrical object is investigated. The experiments are carried out in a direct current (DC) glow discharge dusty plasma in a background of argon gas. Dust particles are found levitated at the interface of plasma and cathode sheath region. The DAWs are spontaneously excited in the dust medium and found to propagate in the direction of ion drift (along the gravity) above a threshold discharge current at low pressure. Excitation of such a low frequency wave is a result of the ion–dust streaming instability in the dust cloud. Characteristics of the propagating dust acoustic wave get modified in the presence of a floating cylindrical object of radius larger than that of the dust Debye length. Instead of propagation in the vertical direction, the DAWs are found to propagate obliquely in the presence of the floating object (kept either vertically or horizontally). In addition, a horizontally aligned floating object forms a wave structure in the cone shaped dust cloud in the sheath region. Such changes in the propagation characteristics of DAWs are explained on the basis of modified potential (or electric field) distribution, which is a consequence of coupling of sheaths formed around the cylindrical object and the cathode.

The Topologies Research of a Soft Switching Bidirectional DC/DC Converter

DEFF Research Database (Denmark)

Zhang, Qi; Zhang, Yongping; Sun, Xiangdong

2017-01-01

A soft-switching solution implemented to the traditional bidirectional DC/DC converter is developed. The soft-switching cell, which composed of three auxiliary switches, one resonant capacitor and one resonant inductor, is equipped in the traditional bidirectional DC/DC converter to realize circuit...... circle. And the proposed topology of bidirectional soft-switching dc-dc converter(TASBC) performs ideal soft switching at boost operations. The characteristics of the proposed converter has been verified by MATLAB simulations and experimental results....

Lifetime test on a high-performance dc microwave proton source

International Nuclear Information System (INIS)

Sherman, J.D.; Hodgkins, D.J.; Lara, P.D.; Schneider, J.D.; Stevens, R.R. Jr.

1995-01-01

Powerful CW proton linear accelerators (100 mA at 0.5--1 GeV) are being proposed for spallation neutron source applications.These production accelerators require high availability and reliability. A microwave proton source, which has already demonstrated several key beam requirements, was operated for one week (170 hours) in a dc mode to test the reliability and lifetime of its plasma generator. The source was operated with 570 W of microwave (2.45 GHz) discharge power and with a 47-kV extraction voltage. This choice of operating parameters gave a proton current density of 250-mA/cm 2 at 83% proton fraction, which is sufficient for a conservative dc injector design. The beam current was 60--65 mA over most of the week, and was sufficiently focused for RFQ injection. Total beam availability, defined as 47-keV beam-on time divided by elapsed time, was 96.2%. Spark downs in the high voltage column and a gas flow control problem caused all the downtime; no plasma generator failures were observed

Graphite electrode DC arc technology program for buried waste treatment

International Nuclear Information System (INIS)

Wittle, J.K.; Hamilton, R.A.; Cohn, D.R.; Woskov, P.P.; Thomas, P.; Surma, J.E.; Titus, C.H.

1994-01-01

The goal of the program is to apply EPI's Arc Furnace to the processing of Subsurface Disposal Area (SDA) waste from Idaho National Engineering Laboratory. This is being facilitated through the Department of Energy's Buried Waste Integrated Demonstration (BWID) program. A second objective is to apply the diagnostics capability of MIT's Plasma Fusion Center to the understanding of the high temperature processes taking place in the furnace. This diagnostics technology has promise for being applicable in other thermal treatment processes. The program has two parts, a test series in an engineering-scale DC arc furnace which was conducted in an EPI furnace installed at the Plasma Fusion Center and a pilot-scale unit which is under construction at MIT. This pilot-scale furnace will be capable of operating in a continuous feed and continuous tap mode. Included in this work is the development and implementation of diagnostics to evaluate high temperature processes such as DC arc technology. This technology can be used as an effective stabilization process for Superfund wastes

Enhancing DC Glow Discharge Tube Museuum Displays using a Theremin Controlled Helmholtz Coil to Demonstrate Magnetic Confinement

Science.gov (United States)

Siu, Theodore; Wissel, Stephanie; Guttadora, Larry; Liao, Susan; Zwicker, Andrew

2010-11-01

Since their discovery in the mid 1800's, DC glow discharge apparatuses have commonly been used for spectral analysis, the demonstration of the Frank-Hertz experiment, and to study plasma breakdown voltages following from the Paschen Curve. A DC glow discharge tube museum display was outfitted with a Helmholtz Coil electromagnet in order to demonstrate magnetic confinement for a science museum display. A device commonly known as a ``theremin'' was designed and built in order to externally control the Helmholtz Coil current and the plasma current. Originally a musical instrument, a theremin has two variable capacitors connected to two radio frequency oscillators which determine pitch and volume. Using a theremin to control current and ``play'' the plasma adds appeal and durability by providing a new innovative means of interacting with a museum exhibit. Educationally, students can use the display to not only learn about plasma properties but also electronic properties of the human body.

75 FR 27401 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-9-30, DC-9-40, and DC-9-50...

Science.gov (United States)

2010-05-17

... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 9-30, DC-9-40, and DC-9-50 Series Airplanes... airworthiness directive (AD) for certain Model DC-9-30, DC-9-40, and DC-9-50 series airplanes. This AD requires... this AD to detect and correct the potential for an arc/spark condition to occur within the fuel boost...

Assessment of the excitation temperatures and Mg II:I line ratios of the direct current (DC) arc source for the analysis of radioactive materials

International Nuclear Information System (INIS)

Manard, B.T.; Matonic, John; Montoya, Dennis; Jump, Robert; Castro, Alonso; Ning Xu

2017-01-01

The direct current (DC) arc plasma has been assessed with an emphasis on excitation temperature (T_e_x_e) and ionization/excitation efficiency by monitoring magnesium ionic:atomic ratios (Mg II:I). The primary goal is to improve the analytical performance of the DC arc instrumentation such that more sensitive and reproducible measurements can be achieved when analyzing trace impurities in nuclear materials. Due to the variety of sample types requiring DC arc analysis, an understanding of the plasma's characteristics will significantly benefit the experimental design when moving forward with LANL's capabilities for trace metal analysis of plutonium metals. (author)

A Feed-Forward Control Realizing Fast Response for Three-Branch Interleaved DC-DC Converter in DC Microgrid

Directory of Open Access Journals (Sweden)

Haojie Wang

2016-07-01

Full Text Available It is a common practice for storage batteries to be connected to DC microgrid buses through DC-DC converters for voltage support on islanded operation mode. A feed-forward control based dual-loop constant voltage PI control for three-branch interleaved DC-DC converters (TIDC is proposed for storage batteries in DC microgrids. The working principle of TIDC is analyzed, and the factors influencing the response rate based on the dual-loop constant voltage control for TIDC are discussed, and then the method of feed-forward control for TIDC is studied to improve the response rate for load changing. A prototype of the TIDC is developed and an experimental platform is built. The experiment results show that DC bus voltage sags or swells caused by load changing can be reduced and the time for voltage recovery can be decreased significantly with the proposed feed-forward control.

A Feed-Forward Control Realizing Fast Response for Three-Branch Interleaved DC-DC Converter in DC Microgrid

DEFF Research Database (Denmark)

Wang, Haojie; Han, Minxiao; Yan, Wenli

2016-01-01

It is a common practice for storage batteries to be connected to DC microgrid buses through DC-DC converters for voltage support on islanded operation mode. A feed-forward control based dual-loop constant voltage PI control for three-branch interleaved DC-DC converters (TIDC) is proposed...... for storage batteries in DC microgrids. The working principle of TIDC is analyzed, and the factors influencing the response rate based on the dual-loop constant voltage control for TIDC are discussed, and then the method of feed-forward control for TIDC is studied to improve the response rate for load...... changing. A prototype of the TIDC is developed and an experimental platform is built. The experiment results show that DC bus voltage sags or swells caused by load changing can be reduced and the time for voltage recovery can be decreased significantly with the proposed feed-forward control....

Using PBL to Improve Educational Outcomes and Student Satisfaction in the Teaching of DC/DC and DC/AC Converters

Science.gov (United States)

Martinez-Rodrigo, Fernando; Herrero-De Lucas, Luis Carlos; de Pablo, Santiago; Rey-Boue, Alexis B.

2017-01-01

This paper examines the question of how to use project-based learning to increase student performance and satisfaction in a power electronics course addressing the topics of dc/dc and dc/ac converters, the assembly of a dc/dc converter, and the use of a commercial speed drive. A detailed presentation of the methodology is shown, and the results…

Improved Control Strategy for T-type Isolated DC/DC Converters

DEFF Research Database (Denmark)

Liu, Dong; Deng, Fujin; Wang, Yanbo

2017-01-01

T-type isolated DC/DC converters have recently attracted attention due to their numerous advantages, including few components, low cost, and symmetrical operation of transformers. This study proposes an improved control strategy for increasing the efficiency of T-type isolated DC/DC converters....... Under the proposed strategy, the primary circulating current flows through the auxiliary switches (metal–oxide–semiconductor field-effect transistors) instead of their body diodes in free-wheeling periods. Such feature can reduce conduction losses, thereby improving the efficiency of T-type isolated DC...

The relationship of plasma decoy receptor 3 and coronary collateral circulation in patients with coronary artery disease.

Science.gov (United States)

Yan, Youyou; Song, Dandan; Liu, Lulu; Meng, Xiuping; Qi, Chao; Wang, Junnan

2017-11-15

Previously, decoy receptor 3 (DcR3) was found to be a potential angiogenetic factor, while the relationship of DcR3 with coronary collateral circulation formation has not been investigated. In this study, we aimed to investigate whether plasma decoy receptor 3 levels was associated with CCC formation and evaluate its predictive power for CCC status in patients with coronary artery disease. Among patients who underwent coronary angiography with coronary artery disease and had a stenosis of ≥90% were included in our study. Collateral degree was graded according to Rentrope Cohen classification. Patients with grade 2 or 3 collateral degree were enrolled in good CCC group and patients with grade 0 or 1 collateral degree were enrolled in poor CCC group. Plasma DcR3 level was significantly higher in good CCC group (328.00±230.82 vs 194.84±130.63ng/l, p<0.01) and positively correlated with Rentrope grade (p<0.01). In addition, plasma DcR3 was also positively correlated with VEGF-A. Both ROC (receiver operating characteristic curve) and multinomial logistical regression analysis showed that plasma DcR3 displayed potent predictive power for CCC status. Higher plasma DcR3 level was related to better CCC formation and displayed potent predictive power for CCC status. Copyright © 2017. Published by Elsevier Inc.

D.C.-arc plasma generator for nonequilibrium plasmachemical processes

International Nuclear Information System (INIS)

Kvaltin, J.

1990-06-01

The analysis is made of the conditions for generation of nonequilibrium plasma in a plasmachemical reactor, and the design is described of a d.c. arc plasma generator based on the integral criterion. Results of measuring potentials on the plasma column of this generator are presented. (author)

High power density dc/dc converter: Selection of converter topology

Science.gov (United States)

Divan, Deepakraj M.

1990-01-01

The work involved in the identification and selection of a suitable converter topology is described. Three new dc/dc converter topologies are proposed: Phase-Shifted Single Active Bridge DC/DC Converter; Single Phase Dual Active Bridges DC/DC Converter; and Three Phase Dual Active Bridges DC/DC Converter (Topology C). The salient features of these topologies are: (1) All are minimal in structure, i.e., each consists of an input and output bridge, input and output filter and a transformer, all components essential for a high power dc/dc conversion process; (2) All devices of both the bridges can operate under near zero-voltage conditions, making possible a reduction of device switching losses and hence, an increase in switching frequency; (3) All circuits operate at a constant frequency, thus simplifying the task of the magnetic and filter elements; (4) Since, the leakage inductance of the transformer is used as the main current transfer element, problems associated with the diode reverse recovery are eliminated. Also, this mode of operation allows easy paralleling of multiple modules for extending the power capacity of the system; (5) All circuits are least sensitive to parasitic impedances, infact the parasitics are efficently utilized; and (6) The soft switching transitions, result in low electromagnetic interference. A detailed analysis of each topology was carried out. Based on the analysis, the various device and component ratings for each topology operating at an optimum point, and under the given specifications, are tabulated and discussed.

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

Directory of Open Access Journals (Sweden)

Liwen Pan

2016-06-01

Full Text Available This paper presents an on-board vehicular battery charger that integrates bidirectional AC/DC converter and DC/DC converter to achieve high power density for application in electric vehicles (EVs. The integrated charger is able to transfer electrical energy between the battery pack and the electric traction system and to function as an AC/DC battery charger. The integrated charger topology is presented and the design of passive components is discussed. The control schemes are developed for motor drive system and battery-charging system with a power pulsation reduction circuit. Simulation results in MATLAB/Simulink and experiments on a 30-kW motor drive and 3.3-kW AC/DC charging prototype validate the performance of the proposed technology. In addition, power losses, efficiency comparison and thermal stress for the integrated charger are illustrated. The results of the analyses show the validity of the advanced integrated charger for electric vehicles.

Fluctuation-Coupling of Cathode Cavity Pressure and Arc Voltage in a dc Plasma Torch with a Long Inter-Electrode Channel at Reduced Pressure

International Nuclear Information System (INIS)

Cao Jin-Wen; Huang He-Ji; Pan Wen-Xia

2014-01-01

Fluctuations of cathode cavity pressure and arc voltage are observed experimentally in a dc plasma torch with a long inter-electrode channel. The results show that they have the same frequency of around 4 kHz under typical experimental conditions. The observed phase difference between the pressure and the voltage, which is influenced by the path length between the pressure sensor and the cathode cavity, varies with different input powers. Combined with numerical simulation, the position of the pressure perturbation origin is estimated, and the results show that it is located at 0.01–0.05 m upstream of the inter-electrode channel outlet

Operational characteristics of the high flux plasma generator magnum-PSI

NARCIS (Netherlands)

Van Eck, H.J.N.; Abrams, T.; Van Den Berg, M.A.; Brons, S.D.N.; Van Eden, G.G.; Jaworski, M.A.; Kaita, R.; Van Der Meiden, H.J.; Morgan, T.W.; van de Pol, Marc J.; Scholten, J.; Smeets, P.H.M.; De Temmerman, G.; De Vries, P.C.; Zeijlmans Van Emmichoven, P.A.

2014-01-01

In Magnum-PSI (MAgnetized plasma Generator and NUMerical modeling for Plasma Surface Interactions), the high density, low temperature plasma of a wall stabilized dc cascaded arc is confined to a magnetized plasma beam by a quasi-steady state axial magnetic field up to 1.3 T. It aims at conditions

Graphite electrode DC arc furnace. Innovative technology summary report

International Nuclear Information System (INIS)

1999-05-01

The Graphite Electrode DC Arc Furnace (DC Arc) is a high-temperature thermal process, which has been adapted from a commercial technology, for the treatment of mixed waste. A DC Arc Furnace heats waste to a temperature such that the waste is converted into a molten form that cools into a stable glassy and/or crystalline waste form. Hazardous organics are destroyed through combustion or pyrolysis during the process and the majority of the hazardous metals and radioactive components are incorporated in the molten phase. The DC Arc Furnace chamber temperature is approximately 593--704 C and melt temperatures are as high as 1,500 C. The DC Arc system has an air pollution control system (APCS) to remove particulate and volatiles from the offgas. The advantage of the DC Arc is that it is a single, high-temperature thermal process that minimizes the need for multiple treatment systems and for extensive sorting/segregating of large volumes of waste. The DC Arc has the potential to treat a wide range of wastes, minimize the need for sorting, reduce the final waste volumes, produce a leach resistant waste form, and destroy organic contaminants. Although the DC arc plasma furnace exhibits great promise for treating the types of mixed waste that are commonly present at many DOE sites, several data and technology deficiencies were identified by the Mixed Waste Focus Area (MWFA) regarding this thermal waste processing technique. The technology deficiencies that have been addressed by the current studies include: establishing the partitioning behavior of radionuclides, surrogates, and hazardous metals among the product streams (metal, slag, and offgas) as a function of operating parameters, including melt temperature, plenum atmosphere, organic loading, chloride concentration, and particle size; demonstrating the efficacy of waste product removal systems for slag and metal phases; determining component durability through test runs of extended duration, evaluating the effect of

RESONANT STEP-DOWN DC-DC POWER CONVERTERS

DEFF Research Database (Denmark)

2015-01-01

The present invention relates to a resonant step-down DC-DC power converter which comprises a primary side circuit and a secondary side circuit coupled through a galvanic isolation barrier. The primary side circuit comprises a positive and a negative input terminal for receipt of an input voltage...... charged from the input voltage and discharged to the output capacitor through the galvanic isolation barrier by a semiconductor switch arrangement in accordance with a switch control signal to produce the converter output voltage. The resonant step-down DC-DC power converter comprises an electrical short......-circuit connection across the galvanic isolation barrier connecting, in a first case, the second negative electrode of the output capacitor to the positive input terminal of the primary side circuit or, in a second case, connecting the second positive electrode of the output capacitor to the negative input terminal...

Atmel Microcontroller Based Soft Switched PWM ZVS Full Bridge DC to DC Converter

Directory of Open Access Journals (Sweden)

DEEPAK KUMAR NAYAK

2010-12-01

Full Text Available This paper deals with the simulation and implementation of soft switched PWM ZVS full bridge DC to DC converter. The 48V DC is efficiently reduced to 12V DC using a DC to DC converter. This converter has advantages like reduced switching losses, stresses and EMI. Input DC is converted into high frequency AC and it is stepped down to 12V level. Later it is rectified using a full wave rectifier. Laboratory model of microcontroller based DC to DC converter is fabricated and tested. The experimental results are compared with the simulation results.

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

International Nuclear Information System (INIS)

Baba, K.; Hatada, R.

2003-01-01

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

Microwave plasma source having improved switching operation from plasma ignition phase to normal ion extraction phase

International Nuclear Information System (INIS)

Sakudo, N.; Abe, K.; Koike, H.; Okada, O.; Tokiguchi, K.

1985-01-01

In a microwave plasma source, a discharge space supplied with a microwave electric field is supplied with a DC magnetic field. A material to be ionized is introduced into the discharge space to produce plasma, whereby ions are extracted through an ion extracting system. A switch is provided for effecting through switching operation the change-over of the magnetic field applied to the discharge space from the intensity for the ignition of plasma to the intensity for ion extraction in succession to completion of the plasma ignition

Quasi-Z-Source Half-Bridge DC-DC Converter for Photovoltaic Applications

OpenAIRE

Vinnikov, D; Chub, A; Husev, O; Zaķis, J

2015-01-01

This paper presents a novel quasi-Z-source halfbridge galvanically isolated DC-DC converter intended for the photovoltaic applications. The topology could be envisioned as an alternative to the boost half-bridge DC-DC converter but the benefit of its symmetric structure reduces the threat of transformer saturation due to the dc flux. The proposed converter features the continuous input current and could be used either with one or two input voltage sources.

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

OpenAIRE

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

2016-01-01

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

DC response of dust to low frequency AC signals

Science.gov (United States)

McKinlay, Michael; Konopka, Uwe; Thomas, Edward

2017-10-01

Macroscopic changes in the shape and equilibrium position of clouds of charged microparticles suspended in a plasma have been observed in response to low frequency AC signals. In these experiments, dusty plasmas consisting of 2-micron diameter silica microspheres suspended between an anode and cathode in an argon, DC glow discharge plasma are produced in a grounded, 6-way cross vacuum chamber. An AC signal, produced by a function generator and amplified by a bipolar op-amp, is superimposed onto the potential from the cathode. The frequencies of the applied AC signals, ranging from tens to hundreds of kHz, are comparable to the ion-neutral collision frequency; well below the ion/electron plasma frequencies, but also considerably higher than the dust plasma frequency. This presentation will detail the experimental setup, present documentation and categorization of observations of the dust response, and present an initial model of the response. This work is supported by funding from the US Dept. of Energy, Grant Number DE-SC0016330, and by the National Science Foundation, Grant Number PHY-1613087.

Control of the DC-DC Converter used into Energy Generation System

International Nuclear Information System (INIS)

Bizon, Nicu; Oproescu, Mihai

2006-01-01

This paper presents an investigation of the DC-DC Converter controller used into Energy Generation System. The full bridge is used into an Energy Generation System (EGS) as second power interface between the energy source and the high DC bus. The simulation results show that the DC-DC Converter behavior can be improved using a well designed PI control surface. The used Simulink models for the EGS blocks and some design considerations are presented, too. (authors)

Spontaneous electromagnetic emission from a strongly localized plasma flow.

Science.gov (United States)

Tejero, E M; Amatucci, W E; Ganguli, G; Cothran, C D; Crabtree, C; Thomas, E

2011-05-06

Laboratory observations of electromagnetic ion-cyclotron waves generated by a localized transverse dc electric field are reported. Experiments indicate that these waves result from a strong E×B flow inhomogeneity in a mildly collisional plasma with subcritical magnetic field-aligned current. The wave amplitude scales with the magnitude of the applied radial dc electric field. The electromagnetic signatures become stronger with increasing plasma β, and the radial extent of the power is larger than that of the electrostatic counterpart. Near-Earth space weather implications of the results are discussed.

Caracterização por FT-IR da superfície de borracha EPDM tratada via plasma por micro-ondas FT-IR characterization of EPDM rubber surface treated by microwave plasma

Directory of Open Access Journals (Sweden)

Renata P. dos Santos

2012-01-01

Full Text Available A superfície de uma borracha de etileno-propileno-dieno (EPDM vulcanizada foi modificada via plasma por microondas, com gases Ar, Ar/O2, N2/O2 e N2/H2, tendo como objetivo melhorar as propriedades adesivas da superfície. A técnica FT-IR/UATR foi escolhida para caracterizar as superfícies após tratamento, pois apresentou menor interferência dos ingredientes da formulação da EPDM, dentre as técnicas analisadas (ATR/KRS-5 e Ge. Grupos oxigenados foram inseridos na superfície da amostra tratada, mesmo quando não foi utilizado o oxigênio, pois estes grupos foram formados quando a superfície ativada foi exposta à atmosfera. Já em tratamentos contendo N2, grupos oxigenados e possíveis grupos nitrogenados foram identificados por FT-IR. Redução nos valores do ângulo de contato, aumento no trabalho de adesão e aumento no ensaio de resistência ao descascamento (EPDM × Poliuretano foram observados após tratamento com Ar e N2/H2, resultando em melhora nas propriedades adesivas da superfície tratada.The surface of a vulcanized ethylene propylene diene monomer (EPDM rubber was modified by microwave plasma in Ar, Ar/O2, N2/O2 and N2/H2 in order to improve the adhesion properties. Surface modification was characterized by FT-IR/UATR, because this technique showed smaller interference of ingredients of EPDM formulation in comparison with other techniques used (ATR KRS-5 and Ge. Oxygenated groups were introduced in the EPDM surface after treatment, even in treatments without oxygen. Theses groups were formed when the activated surface was exposed to the atmosphere. In treatments with nitrogen, oxygenated and possible nitrogenated groups were identified by FT-IR. Reduction in the contact angle, increase in the work of adhesion and increase in the peel strength (EPDM × Polyurethane were observed after treatment with Ar and N2/H2, resulting in improved adhesion properties of the modified surface.

Production of ethanol from mesquite [Prosopis juliflora (SW D.C.] pods mash by Zymomonas mobilis in submerged fermentation Produção de etanol a partir do mosto de vagens de algaroba [Prosopis juliflora (SW D.C.] por Zymomonas mobilis em fermentação submersa

Directory of Open Access Journals (Sweden)

Celiane Gomes Maia da Silva

2011-02-01

Full Text Available Mesquite [Prosopis juliflora (SW D.C.], a perennial tropical plant commonly found in Brazilian semi-arid region, is a viable raw material for fermentative processes because of its low cost and production of pods with high content of hydrolysable sugars which generate many compounds, including ethanol. This study aimed to evaluate the use of mesquite pods as substrate for ethanol production by Z. mobilis UFPEDA205 in a submerged fermentation. The fermentation was assessed for rate of substrate yield to ethanol, rate of ethanol production and efficiency of fermentation. The very close theoretical (170 g L-1 and experimental (165 g L-1 maximum ethanol yields were achieved at 36 h of fermentation. The highest counts of Z. mobilis UFEPEDA-205 (both close to 6 Log cfu mL-1 were also noted at 36 h. Highest rates of substrate yield to ethanol (0.44 g ethanol g glucose-1, of ethanol production (4.69 g L-1 h-1 and of efficiency of fermentation (86.81% were found after 30 h. These findings suggest mesquite pods as an interesting substrate for ethanol production using submerged fermentation by Z. mobilis.A algaroba [Prosopis juliflora (SW D.C.] é uma planta tropical perene comumente encontrada no semi-árido brasileiro e apresenta-se como matéria-prima viável para o processo fermentativo por possuir baixo custo e para produzir vagens que contém um elevado teor de açúcares hidrolisáveis, os quais podem gerar diversos compostos, incluindo etanol. Avaliou-se o uso de vagens de algaroba como substrato para produção de etanol por Z. mobilis UFPEDA-205 por meio de fermentação submersa. O processo fermentativo foi avaliado por meio da mensuração da taxa de conversão de substrato em etanol, taxa de produção de etanol e eficiência de fermentação. Os valores muito próximos encontrados para o fornecimento máximo teórico (170 g L-1 e experimental (165 g L-1 de etanol foram alcançados após 36 h de fermentação. O valor de contagem experimental

Electrochemical Impedance and Polarization Corrosion Studies of Tantalum Surface Modified by DC Plasma Electrolytic Oxidation

Directory of Open Access Journals (Sweden)

Maciej Sowa

2018-04-01

Full Text Available Tantalum has recently become an actively researched biomaterial for the bone reconstruction applications because of its excellent corrosion resistance and successful clinical records. However, a bare Ta surface is not capable of directly bonding to the bone upon implantation and requires some method of bioactivation. In this study, this was realized by direct current (DC plasma electrolytic oxidation (PEO. Susceptibility to corrosion is a major factor determining the service-life of an implant. Therefore, herein, the corrosion resistance of the PEO coatings on Ta was investigated in Ringer’s solution. The coatings were formed by galvanostatic anodization up to 200, 300 and 400 V, after which the treatment was conducted potentiostatically until the total process time amounted to 5 min. Three solutions containing Ca(H2PO22, Ca(HCOO2 and Mg(CH3COO2 were used in the treatment. For the corrosion characterization, electrochemical impedance spectroscopy and potentiodynamic polarization techniques were chosen. The coatings showed the best corrosion resistance at voltages low enough so that the intensive sparking was absent, which resulted in the formation of thin films. The impedance data were fitted to the equivalent electrical circuits with two time constants, namely R(Q[R(QR] and R(Q[R(Q[RW

Sterilization of Normal Human Plasma and Some of its Fractions by Means of Gamma Rays; Esterilizacion del plasma normal humano y algunas de sus fracciones por medio de radiaciones gamma

Energy Technology Data Exchange (ETDEWEB)

López Martínez de Alva, L.; Crespo, Y M. [Cortina Comision Nacional de Energia Nuclear (Mexico)

1967-09-15

radiaciones ultravioleta. El otro metodo es el uso de la ß-propiolactona que se ha desechado tambien рог las alteraciones que producía en la estructura de las protefnas plasmáticas. El objeto de este trabajo, que debe considerarse como una nota preliminar, es presentar los resultados obtenidos al esterilizar por medio de radiaciones gamma ({sup 60}Co, 1,3316 MeV) con dosis variables de 2, 2,5 у 3 Mrad un producto que, como el plasma que contiene proteínas muy lábiles, podría ser fácilmente alterado en su estructura por la radiacion. Tambien se sometieron a las mismas dosis: fibrogeno puro, gamma globulina pura у albúmina de origen humano; los resultados fueron muy satisfacforios, ya que quedo de manifiesto que no se pudieron demostrar alteraciones apreciables en cuanto a su estructura, solubilidad у características bioquímicas. Mediante pruebas simples de coagulacion se puso de manifiesto que algunas de las proteínas que intervienen en este mecanismo, como la protrombina, el factor Power- Stuart у el factor Hageman, prácticamente no se alteraban. Todas las muestras de plasma у de las diferentes proteínas fueron previamente liofilizadas, procurando que el contenido máximo de humedad fuera de 0,034%, con el objeto de evitar la ionizacion del contenido de agua que la tiansformaría en agua oxigenada que alteraría у oxidaría las proteínas. Los plasmas liofilizados previamente contaminados con diferentes cepas у virus demostraron wue con dosis tan bajas como 2 Mrad quedaban esteriles. Por último, se puso de manifiesto que este es un metodo sencillo у práctico, ya que la esterilizacion puede verificarse en el envase final. (author)

Diversidad genética y estructura de la población de Vibrio choierae en Colombia

Directory of Open Access Journals (Sweden)

Riaño Pachón Diego Mauricio

2003-06-01

Full Text Available Se realizó la electroforesis en gel por campo pulsado (PFGE de los macrofragmentos de restricción de 34 aislamien­tos de Vibrio choierae pertenecientes a la epidemia de cólera que se presentó en Colombia entre 1991 y 1996, adicionalmente se analizaron 3 aislamientos de V. choierae no pertenecientes a esta epidemia y un aislamiento de V fluvialis. La diversidad genética observada para los 38 aislamientos tipificados fue de 0,95 valor muy similar al obtenido por Electroforesis de Enzimas Multilocus (MLEE. No se observó correlación entre las variables que carac­terizan a estos aislamientos (serotipo, origen [clínico o ambiental], departamento, tipo electroforético (MLEE y perfil de macrofragmentos de restricción (PFGE. No se obtuvo evidencia de desequilibrio de ligamiento al evaluar esta población con los marcadores genéticos PFGE y MLEE. Se sugiere que la población de Vibrio choierae en Colom­bia presenta una estructura genética sexual, hipótesis que está soportada por la falta de evidencia de desequilibrio de ligamiento y la ausencia de correlaciones entre las variables epidemiológicas, bioquímicas y moleculares a dispo­sición, y por el alto valor de diversidad genética obtenido, que puede ser el reflejo de la coexistencia de varias líneas de descendencia entre las cuales existe un alto flujo genético. Palabras clave: Vibrio choierae; Electroforesis en gel por campo pulsado; epidemiología molecular; genética de po­blaciones; desequilibrio de ligamiento.

Novel composite resonance DC-DC converter with voltage doubler rectifier

OpenAIRE

Kato, Hisatsugu; Matsuo, Hirohumi; Eguchi, Masaki; Sakamoto, Yukitaka; Nakaishi, Masaki

2009-01-01

This paper deals with a novel composite resonance DC-DC converter with the voltage doubler rectifier, which is developed to be applied to the power conditioner of the photovoltaic generation system. The proposed DC-DC converter has the current and voltage resonance functions. Therefore, the output voltage regulation can be achieved for the large variations of the input voltage and load. Also, this converter has the high power efficiency. The maximum power efficiency 96.1% can be realized.

Ultra-high Efficiency DC-DC Converter using GaN Devices

DEFF Research Database (Denmark)

Ramachandran, Rakesh

2016-01-01

properties of GaN devices can be utilized in power converters to make them more compact and highly efficient. This thesis entitled “Ultra-high Efficiency DC-DC Converter using GaN devices” focuses on achieving ultra-high conversion efficiency in an isolated dc-dc converter by the optimal utilization of Ga...... for many decades. However, the rate of improvement slowed as the silicon power materials asymptotically approached its theoretical bounds. Compared to Si, wideband gap materials such as Silicon Carbide (SiC) and Gallium Nitride (GaN) are promising semiconductors for power devices due to their superior...... in this thesis. Efficiency measurements from the hardware prototype of both the topologies are also presented in this thesis. Finally, the bidirectional operation of an optimized isolated dc-dc converter is presented. The optimized converter has achieved an ultra-high efficiency of 98.8% in both directions...

Characterisation of plasma in a rail gun

Science.gov (United States)

Ray, P. K.

1986-01-01

The mechanism of plasma and projectile acceleration in a DC rail gun is described from a microscopic point of view through the establishment of the Hall field. The plasma conductivity is shown to be a tensor, indicating that there is a small component of current parallel to the direction of acceleration. The plasma characteristics are evaluated in the experiment of Bauer et. al., as a function of plasma mass through a simple fluid mechanical analysis of the plasma. By equating the energy dissipatated in the plasma with the radiation heat loss, the properties of the plasma are determined.

Toward Plasma-Assisted Ignition in Scramjets

National Research Council Canada - National Science Library

Jacobsen, Lance S; Carter, Campbell D; Baurie, Robert A; Jackson, Thomas A

2003-01-01

.... The two plasma torches currently under investigation consist of a DC constricted-arc design from the Virginia Polytechnic Institute and State University and an AC unconstricted-arc design based...

75 FR 61352 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-30, DC-10-30F, DC-10-30F (KC...

Science.gov (United States)

2010-10-05

... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 10-30, DC-10-30F, DC-10-30F (KC-10A and KDC-10...-13 McDonnell Douglas Corporation: Amendment 39-16448; Docket No. FAA-2010-0553; Directorate.... Applicability (c) This AD applies to McDonnell Douglas Corporation Model DC- 10-30, DC-10-30F, DC-10-30F (KC-10A...

Efficacy and safety of argon plasma coagulation for the treatment of hemorrhagic radiation proctitis Eficacia y seguridad de la electrocoagulación con plasma de argón en el tratamiento del sangrado rectal secundario a proctitis por radioterapia

Directory of Open Access Journals (Sweden)

C. de la Serna Higuera

2004-11-01

to persist even after long-term follow-up.Objetivo: evaluar la eficacia, seguridad y curso evolutivo a medio/largo plazo de los pacientes tratados endoscópicamente con plasma de argón en nuestra unidad por sangrado rectal asociado a proctitis por radioterapia. Diseño: estudio descriptivo y retrospectivo a medio/largo plazo. Pacientes, material y métodos: entre julio de 1998 y febrero de 2003, se trataron con plasma de argón 10 pacientes que presentaron rectorragia secundaria a proctitis por radioterapia. Se consideraron criterios de inclusión la existencia de sangrado rectal crónico, presencia de hallazgos endoscópicos compatibles y ausencia de otras lesiones justificativas de sangrado. Se emplearon colonoscopios convencionales y equipo con fuente de gas argón y unidad quirúrgica de alta frecuencia. Se programaron sesiones consecutivas hasta conseguir la total eliminación de las lesiones rectales realizándose seguimiento clínico-evolutivo y valorando tolerancia, eficacia y potenciales complicaciones derivadas de la técnica. Se actualizaron los datos por entrevista personal o encuesta telefónica. Resultados: en todos los casos se consiguió la desaparición del sangrado después de la última sesión de tratamiento. El número medio de sesiones de tratamiento por paciente fue de 1,7. En cuatro casos fue precisa una única sesión. El tiempo medio de seguimiento tras concluir el tratamiento fue de 31,1, meses. En un caso recidivó el sangrado a los 4 meses, siendo precisas dos sesiones adicionales. Cuatro pacientes presentaban inicialmente signos analíticos de anemia que persistía sólo en un caso al final del estudio. No se registraron complicaciones tardías derivadas de la técnica, como úlceras o estenosis rectales. Conclusiones: la electrocoagulación endoscópica con plasma de argón supone en nuestra experiencia, una alternativa segura, eficaz y bien tolerada en el tratamiento del sangrado rectal asociado a la proctitis por radioterapia, con

Sliding-Mode Control of a Charger/Discharger DC/DC Converter for DC-Bus Regulation in Renewable Power Systems

Directory of Open Access Journals (Sweden)

Sergio Ignacio Serna-Garcés

2016-03-01

Full Text Available Stand-alone power systems based on renewable energy sources are used to replace generators based on fossil fuels. Those renewable power systems also require Energy Storage Devices (ESD interfaced by a charger/discharger power converter, which consist of a bidirectional DC/DC converter, and a DC bus. This paper proposes a single sliding-mode controller (SMC for the charger/discharger DC/DC converter to provide a stable DC bus voltage in any operation condition: charging or discharging the ESD, or even without any power exchange between the ESD and the DC bus. Due to the non-linear nature of the power converter, the SMC parameters are adapted on-line to ensure global stability in any operation condition. Such stability of the adaptive SMC is mathematically demonstrated using analytical expressions for the transversality, reachability and equivalent control conditions. Moreover, a design procedure for the adaptive SMC parameters is provided in order to ensure the dynamic response required for the correct operation of the load. Finally, simulations and experimental tests validate the proposed controller and design procedure.

The TRIUMF compact DC H-/D- ion source

International Nuclear Information System (INIS)

Jayamanna, K.; McDonald, M.; Yuan, D.H.; Schmor, P.W.

1990-06-01

A compact dc H - /D - ion source using multicusp magnetic plasma confinement, has been experimentally studied and optimized on the TRIUMF ion source test stand. The plasma parameters have been obtained with rapid computer controlled Langmuir probe scans. The extraction electrode configuration, originally tailored to the TR30 cyclotron requirements, has been further developed. With a 12 mm diameter extraction hole this source now provides 9 mA within a normalized emittance of 0.44 π mm-mrad and can be easily modified for lower currents of smaller emittance (1 mA H - current with normalized emittance 0.12π.mm-mrad or 7 mA H - current with normalized emittance 0.34π.mm-mrad). The source has proven to have low maintenance, high reliability and long filament lifetime. This paper emphasizes basic plasma parameters which determine the efficiency of H - /D - production. Some experimental results obtained from several versions of the extraction system are also described. (Author) 6 refs., 8 figs

Design and Analysis of Two-Phase Boost DC-DC Converter

OpenAIRE

Taufik Taufik; Tadeus Gunawan; Dale Dolan; Makbul Anwari

2010-01-01

Multiphasing of dc-dc converters has been known to give technical and economical benefits to low voltage high power buck regulator modules. A major advantage of multiphasing dc-dc converters is the improvement of input and output performances in the buck converter. From this aspect, a potential use would be in renewable energy where power quality plays an important factor. This paper presents the design of a 2-phase 200W boost converter for battery charging application. Analysis of results fr...

SCM Handbooks for dc-to-dc Converters

Science.gov (United States)

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

1984-01-01

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

Isolated step-down DC -DC converter for electric vehicles

Science.gov (United States)

Kukovinets, O. V.; Sidorov, K. M.; Yutt, V. E.

2018-02-01

Modern motor-vehicle industrial sector is moving rapidly now towards the electricity-driving cars production, improving their range and efficiency of components, and in particular the step-down DC/DC converter to supply the onboard circuit 12/24V of electric vehicle from the high-voltage battery. The purpose of this article - to identify the best circuitry topology to design an advanced step-down DC/DC converters with the smallest mass, volume, highest efficiency and power. And this will have a positive effect on driving distance of electric vehicle (EV). On the basis of computational research of existing and implemented circuit topologies of step-down DC/DC converters (serial resonant converter, full bridge with phase-shifting converter, LLC resonant converter) a comprehensive analysis was carried out on the following characteristics: specific volume, specific weight, power, efficiency. The data obtained was the basis for the best technical option - LLC resonant converter. The results can serve as a guide material in the process of components design of the traction equipment for electric vehicles, providing for the best technical solutions in the design and manufacturing of converting equipment, self-contained power supply systems and advanced driver assistance systems.

Computational study of plasma-solid interaction in DC glow discharge in argon plasma at medium pressures

International Nuclear Information System (INIS)

Havlickova, E; Bartos, P; Hrach, R

2007-01-01

In the presented contribution two groups of techniques of computational physics-fluid modelling and non self-consistent particle technique were used to study plasma-solid interaction in argon plasma. We focused both on the physical processes taking place in the sheath at various pressures and on the problems of computational physics. The attention was given to preparation of two-dimensional fluid models with realistic assumptions about physical processes taking place in plasma during the plasma-solid interaction, further to improvement of the non self-consistent technique of particle modelling, where the external electric field was obtained either from the fluid model or directly from the trajectories of charged particles and finally to efficiency of individual algorithms

A mechanical arcless dc circuit breaker for a superconducting magnet system

International Nuclear Information System (INIS)

Yamaguchi, S.; Sasao, H.; Matumura, Y.; Tukamoto, T.

1993-01-01

Next fusion research experiments plan to use many superconducting magnets. When a quench phenomenon is observed, the current should be interrupted to protect the magnet. Therefore, a dc circuit breaker is necessary. There are four technical situations to be considered for the dc circuit breaker system; (1) high rated current, (2) smaller size breaker, (3) high reliability and (4) no surge voltage during the interruption. The sizer of the breaker is limited by the arc current density of the contacts, and the low current density is better in the circuit breakers. A high rated current also needs the large contacts of the breaker. Here, we introduce a new type of dc circuit breaker system which does not generate an arc plasma between the contacts, equip the high rated current disconnecting switch and a fuse for the failure of the interruption, and use the conventional ac breaker. The switch size of the breaker is almost one hundred times smaller than that of the previous switch. (orig.)

Development of plasma diagnostics technologies - Measurement of transport= parameters in tokamak edge plasma by using electric transport probes

Energy Technology Data Exchange (ETDEWEB)

Chung, Kyu Sun; Chang, Do Hee; Sim, Yeon Gun; Kim, Jin Hee [Hanyang University, Seoul (Korea, Republic of)

1995-08-01

Electric transport probe system is developed for the measurement of electron temperature, floating potential, plasma density and flow velocity of= edge plasmas in the KT-2 medium size tokamak. Experiments have been performed in KT-1 small size tokamak. Electric transport probe is composed of a single probe(SP) and a Mach probe (MP). SP is used for the measurements of electron density, floating potential, and plasma density and measured values are {approx} 3*10{sup 11}/cm{sup -3}, -20 volts, 15 {approx} 25 eV. For the most discharges, respectively. MP is for the measurements of toroidal(M{sub T}) and poloidal(M{sub P}) flow velocities, and density, which are M{sub T} {approx_equal} .0.85, M{sub P} {approx_equal}. 0.17, n. {approx_equal} 2.1*10{sup 11} cm{sup -3}, respectively. A triple probe is also developed for the direct reading of T{sub e} and n{sub e}, and is used for DC, RF, and RF+DC plasma in APL of Hanyang university. 38 refs., 36 figs. (author)

75 FR 75872 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-9-30, DC-9-40, and DC-9-50...

Science.gov (United States)

2010-12-07

... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 9-30, DC-9-40, and DC-9-50 Series Airplanes...: We are adopting a new airworthiness directive (AD) for the McDonnell Douglas Corporation airplanes... to include an airworthiness directive (AD) that would apply to certain McDonnell Douglas Model DC-9...

Flute Characteristics of and Microwave Emission from a Plasma in a Mirror; Instabilite en Cannelures et Emission de Micro-Ondes par un Plasma dans une Machine a Miroirs; Zhelobkovye kharakteristiki i ehmissiya mikrovoln iz plazmy v zerkale; Caracteristicas del Estriado y Emision de Microondas por un Plasma en un Espejo

Energy Technology Data Exchange (ETDEWEB)

Scott, F. R.; Jensen, T. H.; Wharton, C. B. [General Atomic Division, General Dynamics Corporation, San Diego, CA (United States)

1966-04-15

, si l'energie des electrons est suffisamment superieure a celle des ions. L'addition de plaques conductrices dans la region aval du miroir a pour effet d'attenuer la violence de l'instabilite en cannelures. Cette attenuation ne depend que de la resistance surfacique de ces plaques. Les auteurs ont etudie cet effet en mesurant le spectre de frequence des signaux en provenance de sondes a sintillateur enrobe placees au voisinage de l'enceinte a vide. (author) [Spanish] Los autores construyeron un espejo pulsado para estudiar la estabilidad de un plasma de modesta energfa. El plasma de 70 eV se inyecta mediante un cation en el espejo, con ayuda de un campo de gufa octopolar de tipo lineal. El campo especular se aplica durante un lapso igual al tiempo de transito del plasma. En el plano central del espejo se alcanzan densidades de plasma iguales a 10{sup 13} electrones/cm{sup 3}. Se observan dos modos definidos de operacion, dependientes exclusivamente de las condiciones establecidas en el campo de gufa. Segun el primer modo, en el espejo el plasma no sufre estriado alguno, la mayor parte del mismo escapa en direccion axial, se observa una lenta, y anomala difusion radial y se emiten microondas en los ar- . monicos ciclotronicos de los electrones, desde n = 1 hasta por lo menos n = 19. La emision de microondas no es compatible con la rama electronica de la inestabilidad de Harris. La estabilidad de este modo se atribuye a la union lineal por el plasma frio que sale por efusion de la zona del campo de gufa. En la zona comprendida entre el espejo y el campo de gufa, se observaron densidades superiores a 10{sup 11} electrones/cm{sup 3} durante 200 {mu}s. Esta densidad disminuye al agregar al campo de gufa un cilindro de simetria axial. Al cabo de 40 us, las mediciones ponen de manifiesto en esta zona densidades de plasma inferiores 10{sup 11} electrones/cm{sup 3}. El plasma resultante, atrapado en el espejo presenta inestabilidades en forma de estrias, perdidas radiales

A Component-Reduced Zero-Voltage Switching Three-Level DC-DC Converter

DEFF Research Database (Denmark)

Qin, Zian; Pang, Ying; Wang, Huai

2016-01-01

The basic Zero-Voltage Switching (ZVS) three-level DC-DC converter has one clamping capacitor to realize the ZVS of the switches, and two clamping diodes to clamp the voltage of the clamping capacitor. In order to reduce the reverse recovery loss of the diode as well as its cost, this paper...... proposes to remove one of the clamping diodes in basic ZVS three-level DC-DC converter. With less components, the proposed converter can still have a stable clamping capacitor voltage, which is clamped at half of the dc link voltage. Moreover, the ZVS performance will be influenced by removing the clamping...

Dust Transport And Force Equilibria In Magnetized Dusty DC Discharges

International Nuclear Information System (INIS)

Land, Victor; Thomas, Edward Jr.; Williams, Jeremaiah

2005-01-01

We have performed experiments on magnetized dusty Argon DC discharges. Here we report on the characterization of the plasma- and the dustparameters and on the response of the dust particles and the plasma to a change in the magnetic configuration inside the discharge. Finally, we show a case in which the balance of forces acting on the dust particles differs from the classical balance (in which the electrostatic force balances the downward force of gravity). In this case the electrostatic force acts as a downward force on the dust particles. From observations we will argue that the ion drag force might be the force that balances this downward electrostatic force

Active pre-filters for dc/dc Boost regulators

Directory of Open Access Journals (Sweden)

Carlos Andrés Ramos-Paja

2014-05-01

Full Text Available This paper proposes an active pre-filter to mitigate the current harmonics generated by classical dc/dc Boost regulators, which generate current ripples proportional to the duty cycle. Therefore, high output voltage conditions, i.e., high voltage conversion ratios, produce high current harmonics that must be filtered to avoid damage or source losses. Traditionally, these current components are filtered using electrolytic capacitors, which introduce reliability problems because of their high failure rate. The solution introduced in this paper instead uses a dc/dc converter based on the parallel connection of the Boost canonical cells to filter the current ripples generated by the Boost regulator, improving the system reliability. This solution provides the additional benefits of improving the overall efficiency and the voltage conversion ratio. Finally, the solution is validated with simulations and experimental results.

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

CERN Document Server

Kazimierczuk, Marian K

2015-01-01

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

A Novel PPFHB Bidirectional DC-DC Converter for Supercapacitor Application

DEFF Research Database (Denmark)

Zhang, Zhe; Thomsen, Ole Cornelius; Andersen, Michael Andreas E.

2009-01-01

This paper presents a novel bidirectional DC-DC converter for the supercapacitor application. In the proposed converter, push-pull forward with half bridge (PPFHB) voltage doubler structure is used to reduce the number of the power switches and get higher voltage gain. Based on phase-shift modula......This paper presents a novel bidirectional DC-DC converter for the supercapacitor application. In the proposed converter, push-pull forward with half bridge (PPFHB) voltage doubler structure is used to reduce the number of the power switches and get higher voltage gain. Based on phase...

Decentralized Interleaving of Paralleled Dc-Dc Buck Converters: Preprint

Energy Technology Data Exchange (ETDEWEB)

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

2017-09-01

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

Surface stoichiometry modification and improved DC/RF characteristics by plasma treated and annealed AlGaN/GaN HEMTs

Science.gov (United States)

Upadhyay, Bhanu B.; Takhar, Kuldeep; Jha, Jaya; Ganguly, Swaroop; Saha, Dipankar

2018-03-01

We demonstrate that N2 and O2 plasma treatment followed by rapid thermal annealing leads to surface stoichiometry modification in a AlGaN/GaN high electron mobility transistor. Both the source/drain access and gate regions respond positively improving the transistor characteristics albeit to different extents. Characterizations indicate that the surface show the characteristics of that of a higher band-gap material like AlxOy and GaxOy along with N-vacancy in the sub-surface region. The N-vacancy leads to an increased two-dimensional electron gas density. The formation of oxides lead to a reduced gate leakage current and surface passivation. The DC characteristics show increased transconductance, saturation drain current, ON/OFF current ratio, sub-threshold swing and lower ON resistance by a factor of 2.9, 2.0, 103.3 , 2.3, and 2.1, respectively. The RF characteristics show an increase in unity current gain frequency by a factor of 1.7 for a 500 nm channel length device.

Mortalidad infantil por defectos congénitos en Costa Rica, 1981-2010

Directory of Open Access Journals (Sweden)

María de la Paz Barboza-Arguello

2013-11-01

Full Text Available OBJETIVO: Identificar las tendencias y el impacto de los diferentes tipos de defectos congénitos (DC en la tasa de mortalidad infantil (TMI y neonatal (TMN en Costa Rica para el período 1981-2010. MÉTODOS: Se analizaron datos del Centro Centroamericano de Población, que utiliza las versiones 9 y 10 de la Clasificación Internacional de Enfermedades para clasificar las causas de defunción. Se analizaron tendencias de mortalidad infantil, neonatal y residual. Para cada grupo de DC se construyó un modelo de regresión Poisson Log Lineal. Se obtuvieron las TMI y las TMN y los riesgos relativos correspondientes a las tres décadas 1981-1990, 1991-2000 y 2001-2010, con sus intervalos de confianza de 95% (IC95%. Los estimados se compararon mediante chi cuadrado de Wald. RESULTADOS: Al comparar la década de 1980 con la del 2000, la TMN y la TMI por DC presentó una disminución significativa de 2,37 (IC95%: 2,26-2,48 a 2,13 (2,03-2,23 y de 4,13 (3,99-4,27 a 3,18 (3,05-3,31, respectivamente. Los grupos de DC que registraron una reducción significativa en la TMI fueron: sistema nervioso, digestivo y circulatorio. Con excepción del sistema circulatorio, estos grupos experimentaron una caída significativa en la TMN. En el resto de los grupos se registró un aumento significativo o no hubo cambio. CONCLUSIONES: Se ha producido una disminución de la TMI y la TMN por DC, aunque proporcionalmente estas tasas han crecido debido a un mayor descenso de las otras causas. Esta reducción es mucho menor en la mortalidad neonatal. Se debe fortalecer la prevención primaria y la atención neonatal de los DC.

ELECTROMAGNETIC COMPATIBILITY OF A DC POWER DISTRIBUTION SYSTEM FOR THE ATLAS LIQUID ARGON CALORIMETER COMPATIBILIDAD ELECTROMAGNÉTICA EN EL SISTEMA DE DISTRIBUCIÓN DE CORRIENTE CONTINUA PARA EL CALORÍMETRO DE ARGÓN LÍQUIDO EN ATLAS

Directory of Open Access Journals (Sweden)

George Blanchot

2008-06-01

Full Text Available The front-end electronics of the ATLAS Liquid Argon Calorimeter is powered by DC/DC converters nearby the front-end crates. They are fed by AC/DC converters located in a remote control room through long power cables. The stability of the power distribution scheme is compromised by the impedance of the long interconnection cable, and proper matching of the converters dynamic impedances is required. Also, the long power cable fed by a powerful AC/DC converter is a source of electromagnetic interferences in the experimental area. The optimal grounding and shielding configuration to minimize these EMI is discussed.El Calorímetro de Argón Líquido en ATLAS es alimentado por convertidores DC/DC localizados cerca de sus compartimientos. Ellos son alimentados por convertidores AC/DC localizados en una sala de control lejana conectados mediante cables largos de poder. La estabilidad del sistema de distribución es sensible a la impedancia del cable largo de interconexión y son requeridos los convertidores apropiados para estabilizar la dinámica de la impedancia. También, el cable largo alimentado por el convertidor AC/DC es una fuente de interferencia electromagnética en el área experimental. En este trabajo se analiza La óptima configuración de aterrizamiento y blindaje para minimizar los efectos de EMI.

CISH is induced during DC development and regulates DC-mediated CTL activation.

Science.gov (United States)

Miah, Mohammad Alam; Yoon, Cheol-Hee; Kim, Joonoh; Jang, Jinah; Seong, Young-Rim; Bae, Yong-Soo

2012-01-01

The cytokine inducible SH2-domain protein (CISH) is a well-known STAT5 target gene, but its role in the immune system remains uncertain. In this study, we found that CISH is predominantly induced during dendritic cell (DC) development from mouse bone marrow (BM) cells and plays a crucial role in type 1 DC development and DC-mediated CTL activation. CISH knockdown reduced the expression of MHC class I, co-stimulatory molecules and pro-inflammatory cytokines in BMDCs. Meanwhile, the DC yield was markedly enhanced by CISH knockdown via cell-cycle activation and reduction of cell apoptosis. Down-regulation of cell proliferation at the later stage of DC development was found to be associated with CISH-mediated negative feedback regulation of STAT5 activation. In T-cell immunity, OT-1 T-cell proliferation was significantly reduced by CISH knockdown in DCs, whereas OT-2 T-cell proliferation was not affected by CISH knockdown. CTLs generated by DC vaccination were also markedly reduced by CISH knockdown, followed by significant impairment of DC-based tumor immunotherapy. Taken together, our data suggest that CISH expression at the later stage of DC development triggers the shutdown of DC progenitor cell proliferation and facilitates DC differentiation into a potent stimulator of CTLs. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

Science.gov (United States)

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

2017-07-01

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

Plasma methods for metals recovery from metal-containing waste.

Science.gov (United States)

Changming, Du; Chao, Shang; Gong, Xiangjie; Ting, Wang; Xiange, Wei

2018-04-27

Metal-containing waste, a kind of new wastes, has a great potential for recycling and is also difficult to deal with. Many countries pay more and more attention to develop the metal recovery process and equipment of this kind of waste as raw material, so as to solve the environmental pollution and comprehensively utilize the discarded metal resources. Plasma processing is an efficient and environmentally friendly way for metal-containing waste. This review mainly discuss various metal-containing waste types, such as printed circuit boards (PCBs), red mud, galvanic sludge, Zircon, aluminium dross and incinerated ash, and the corresponding plasma methods, which include DC extended transferred arc plasma reactor, DC non-transferred arc plasma torch, RF thermal plasma reactor and argon and argon-hydrogen plasma jets. In addition, the plasma arc melting technology has a better purification effect on the extraction of useful metals from metal-containing wastes, a great capacity of volume reduction of waste materials, and a low leaching toxicity of solid slag, which can also be used to deal with all kinds of metal waste materials, having a wide range of applications. Copyright © 2018 Elsevier Ltd. All rights reserved.

Espécies novas de Myrcia DC. e Marlierea Cambes. (Myrtaceae New species of Myrcia DC. and Marlierea Cambes. (Myrtaceae

Directory of Open Access Journals (Sweden)

Graziela Maciel Barroso

1990-12-01

Full Text Available O trabalho trata de espécies novas de Myrcia DC. e Marlierea Cambes., dois gêneros de Myrtaceae da sub tribo Myrciinae, da Reserva Florestal de Linhares, Espírito Santo, Brasil. Na área são conhecidas 18 espécies de Myrcia, 5 das quais são agora descritas. O gênero Marlierea está representado por 12 espécies, uma das quais é descrita como nova. Os novos taxa são ilustrados, e feitos comentários sobre relacionamento entre espécies afins.This paper deals with new species of Myrcia DC. and Marlierea Cambes., two genera of Myrtaceae subtribus Myrciinae, from the Reserva Florestal of Linhares, Espírito Santo, Brazil. From this area, 18 species of Myrcia are known, 5 of which are new to science and described here. Marlierea is not as rich in species as Myrcia but it is represented by 12 species, one here described as new. The new species are illustrated and some remarks are made about their relationships.

Plasma processing of superconducting radio frequency cavities

Science.gov (United States)

Upadhyay, Janardan

The development of plasma processing technology of superconducting radio frequency (SRF) cavities not only provides a chemical free and less expensive processing method, but also opens up the possibility for controlled modification of the inner surfaces of the cavity for better superconducting properties. The research was focused on the transition of plasma etching from two dimensional flat surfaces to inner surfaces of three dimensional (3D) structures. The results could be applicable to a variety of inner surfaces of 3D structures other than SRF cavities. Understanding the Ar/Cl2 plasma etching mechanism is crucial for achieving the desired modification of Nb SRF cavities. In the process of developing plasma etching technology, an apparatus was built and a method was developed to plasma etch a single cell Pill Box cavity. The plasma characterization was done with the help of optical emission spectroscopy. The Nb etch rate at various points of this cavity was measured before processing the SRF cavity. Cylindrical ring-type samples of Nb placed on the inner surface of the outer wall were used to measure the dependence of the process parameters on plasma etching. The measured etch rate dependence on the pressure, rf power, dc bias, temperature, Cl2 concentration and diameter of the inner electrode was determined. The etch rate mechanism was studied by varying the temperature of the outer wall, the dc bias on the inner electrode and gas conditions. In a coaxial plasma reactor, uniform plasma etching along the cylindrical structure is a challenging task due to depletion of the active radicals along the gas flow direction. The dependence of etch rate uniformity along the cylindrical axis was determined as a function of process parameters. The formation of dc self-biases due to surface area asymmetry in this type of plasma and its variation on the pressure, rf power and gas composition was measured. Enhancing the surface area of the inner electrode to reduce the

Factores relacionados con el control exitoso de un brote por Klebsiella pneumoniae productora de KPC-2 en una unidad de cuidado intensivo en Bogotá, Colombia

Directory of Open Access Journals (Sweden)

Gisell Bustos-Moya

Full Text Available La resistencia a carbapenémicos en Klebsiella pneumoniae ha aumentado de manera considerable, incrementando las tasas de morbimortalidad. El objetivo de este trabajo fue describir las características epidemiológicas, microbiológicas y las medidas de intervención que permitieron el control exitoso de un brote de Klebsiella pneumoniae productora de KPC-2. Métodos: El estudio se realizó en 2 periodos: el primero durante el brote, con instauración de un protocolo de medidas de intervención; y el segundo, de seguimiento posbrote. Se realizaron pruebas de identificación y susceptibilidad por sistema automatizado, tamización de carbapenemasas por test de Hodge modificado, PCR para detección de los genes bla KPC , bla KPC-2 , NDM-1 y estudio de clonalidad por electroforesis de campos pulsados. Resultados: Durante el brote, se identificaron 18 aislamientos de Klebsiella pneumoniae productora de KPC en 11 pacientes. Tres casos fueron confirmados como infección intrahospitalaria. La técnica de PCR reveló la presencia del gen bla KPC en 21 de 22 aislamientos (pacientes y medio ambiente y se identificó la presencia de un clon con una similitud superior al 75%. En el periodo posbrote los cultivos ambientales y de búsqueda de colonizados fueron negativos. Discusión: Se evidenció un control exitoso del brote producido por un clon. La implementación de un protocolo de intervención y la monitorización de su cumplimiento, la comunicación efectiva y el trabajo en equipo fueron indispensables para evitar su propagación y evitar un comportamiento endémico posbrote.

Survey of Pulsed Neutron Source Methods for Multiplying Media; Methodes des Neutrons Pulses Pour l'Etude des Milieux Multiplicateurs; Obzor metodov s ispol'zovaniem istochnikov impul'snykh nejtronov dlya razmnozhayushchej sredy; Estudio Panoramico de los Metodos de Empleo de Fuentes de Neutrons Pulsados en Medios Multiplicadores

Energy Technology Data Exchange (ETDEWEB)

Garelis, E. [General Electric Company, Vallecitos Atomic Laboratory, Pleasanton, CA (United States)

1965-10-15

-Small-L ). Il discute en outre l'emploi des methodes qui sont fondees sur la reponse a des impulsions pseudoaleatoires et utilisent une correlation entre l'entree et la sortie, pour la determination de la fonction de Green d'un milieu multiplicateur. H montre que les renseignements obtenus par ces methodes sont identiques a ceux fournis par les methodes de la source puisee a repetition, ce qui permet d'appliquer aux premieres les procedes qui ont ete mis au point pour les secondes. (author) [Spanish] En los ultimos afios ha habido dos tendencias principales acerca de la manera mas eficaz de medir la reactividad de parada, empleando fuentes de neutrones pulsados: la primera preconizaba el empleo de metodos tradicionales de medicion con fuentes neutronicas reiteradamente pulsadas, y la segunda propugnaba la aplicacion de metodos basados en una tecnica seudoaleatoria de respuesta a los impulsos, utilizando una correlacion entre los datos de entrada y los de salida. La informacion obtenida con una y otra tecnica es la misma; en teoria, ambos metodos sirven para determinar la funcion de respuesta. Se resefia el desarrollo de las tecnicas de empleo de fuentes de neutrones pulsados aplicadas a sistemas termicos con miras a medir la reactividad, desde los primeros intentos de Sjoestrand hasta el reciente metodo (k{beta}/ Script-Small-L ). Con el metodo usual de empleo de estas fuentes, la propiedad que se procuia determinar es la funcion de Green del conjunto subercritico empleado, es decir, la respuesta del reactor a una fuente de neutrones de funcion delta. El decrecimiento exponencial (e{sup {alpha}t}) de la funcion de Green proporciona una constante de decrecimiento de los neutrones instantaneos que es independiente del espacio. El autor examina los metodos para obtener el valor de la reactividad partiendo de la medida de a, como por ejemplo el metodo de la medicion de la criticidad por neutrones retardados a y el reciente metodo (k{beta}/ Script-Small-L ). Seguidamente examina el

Influence of substrate dc bias on crystallinity of silicon films grown at a high rate from inductively-coupled plasma CVD

International Nuclear Information System (INIS)

Kosku, N.; Murakami, H.; Higashi, S.; Miyazaki, S.

2005-01-01

We have investigated the effect of substrate bias on the microcrystalline film growth from inductively-coupled plasma (ICP) of H 2 -diluted SiH 4 at 250 deg. C to get an insight on the role of ion and electron incidence for the crystallization. By applying dc bias voltage to the substrate in the range of -20 ∼ 20 V during the film growth, the crystallinity is improved significantly with no significant change in the deposition rate, but in contrast the application of biases as high as ±50 V degrades the crystallinity. These results indicate that the incidence of ions or electrons with a moderate energy to the growing film surface promotes the nucleation and the growth of crystallites. Also, the optimum bias condition for the crystallization is changed with the antenna-substrate distance, which suggests the contribution of hydrogen radical flux to the crystalline film growth

Titanium nitride plasma-chemical synthesis with titanium tetrachloride raw material in the DC plasma-arc reactor

Science.gov (United States)

Kirpichev, D. E.; Sinaiskiy, M. A.; Samokhin, A. V.; Alexeev, N. V.

2017-04-01

The possibility of plasmochemical synthesis of titanium nitride is demonstrated in the paper. Results of the thermodynamic analysis of TiCl4 - H2 - N2 system are presented; key parameters of TiN synthesis process are calculated. The influence of parameters of plasma-chemical titanium nitride synthesis process in the reactor with an arc plasmatron on characteristics on the produced powders is experimentally investigated. Structure, chemical composition and morphology dependencies on plasma jet enthalpy, stoichiometric excess of hydrogen and nitrogen in a plasma jet are determined.

A Bidirectional Multi-Port DC-DC Converter Integrating Voltage Equalizer

DEFF Research Database (Denmark)

Chen, Jianfei; Hou, Shiying; Deng, Fujin

2015-01-01

A novel bidirectional multi-port dc-dc converter integrating voltage equalizer based on switched-capacitor voltage accumulator (SCVA) is proposed. It has two operating modes of charging and discharging for battery modules. All battery modules are connected in series indirectly and can be equalize...... battery modules with different voltages. Simulation results has shown the feasibility of the proposed converter.......A novel bidirectional multi-port dc-dc converter integrating voltage equalizer based on switched-capacitor voltage accumulator (SCVA) is proposed. It has two operating modes of charging and discharging for battery modules. All battery modules are connected in series indirectly and can be equalized...

Diagnostics of Plasma Jet Generated in Water/Argon DC Arc Torch.

Czech Academy of Sciences Publication Activity Database

Hurba, Oleksiy; Hlína, Michal; Hrabovský, Milan

2016-01-01

Roč. 3, č. 1 (2016), s. 5-8 ISSN 2336-2626. [Symposium on Physics of Switching Arc 2015, FSO 2015 /21./. Nové Město na Moravě, 07.09.2015-11.09.2015] R&D Projects: GA ČR(CZ) GA15-19444S Institutional support: RVO:61389021 Keywords : thermal plasma jet * electric probes * schlieren photography * enthalpy probe Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics)

Plasma waves observed by sounding rockets

International Nuclear Information System (INIS)

Kimura, I.

1977-01-01

Observations of plasma wave phenomena have been conducted with several rockets launched at Kagoshima Space Center, Kyushu, Japan, and at Showa Base, Antarctica. This report presents some results of the observations in anticipation of having valuable comments from other plasma physicists, especially from those who are concerned with laboratory plasma. In the K-9M-41 rocket experiment, VLF plasma waves were observed. In this experiment, the electron beam of several tens of uA was emitted from a hot cathode when a positive dc bias changing from 0 to 10V at 1V interval each second was applied to a receiving dipole antenna. The discrete emissions with 'U' shaped frequency spectrum were observed for the dc bias over 3 volts. The U emissions appeared twice per spin period of the rocket. Similar rocket experiment was performed at Showa Base using a loop and dipole antenna and without hot cathode. Emissions were observed with varying conditions. At present, the authors postulate that such emissions may be produced just in the vicinity of a rocket due to a kind of wake effect. (Aoki, K.)

A Current-Fed Isolated Bidirectional DC-DC Converter

DEFF Research Database (Denmark)

Sun, Xiaofeng; Wu, Xiaoying; Shen, Yanfeng

2017-01-01

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

Impact of Plasma Electron Flux on Plasma Damage-Free Sputtering of Ultrathin Tin-Doped Indium Oxide Contact Layer on p-GaN for InGaN/GaN Light-Emitting Diodes.

Science.gov (United States)

Son, Kwang Jeong; Kim, Tae Kyoung; Cha, Yu-Jung; Oh, Seung Kyu; You, Shin-Jae; Ryou, Jae-Hyun; Kwak, Joon Seop

2018-02-01

The origin of plasma-induced damage on a p -type wide-bandgap layer during the sputtering of tin-doped indium oxide (ITO) contact layers by using radiofrequency-superimposed direct current (DC) sputtering and its effects on the forward voltage and light output power (LOP) of light-emitting diodes (LEDs) with sputtered ITO transparent conductive electrodes (TCE) is systematically studied. Changing the DC power voltage from negative to positive bias reduces the forward voltages and enhances the LOP of the LEDs. The positive DC power drastically decreases the electron flux in the plasma obtained by plasma diagnostics using a cutoff probe and a Langmuir probe, suggesting that the repulsion of plasma electrons from the p -GaN surface can reduce plasma-induced damage to the p -GaN. Furthermore, electron-beam irradiation on p -GaN prior to ITO deposition significantly increases the forward voltages, showing that the plasma electrons play an important role in plasma-induced damage to the p -GaN. The plasma electrons can increase the effective barrier height at the ITO/deep-level defect (DLD) band of p -GaN by compensating DLDs, resulting in the deterioration of the forward voltage and LOP. Finally, the plasma damage-free sputtered-ITO TCE enhances the LOP of the LEDs by 20% with a low forward voltage of 2.9 V at 20 mA compared to LEDs with conventional e-beam-evaporated ITO TCE.

Bi-Directional DC-DC Converter for PHEV Applications

Energy Technology Data Exchange (ETDEWEB)

Abas Goodarzi

2011-01-31

Plug-In Hybrid Electric Vehicles (PHEV) require high power density energy storage system (ESS) for hybrid operation and high energy density ESS for Electric Vehicle (EV) mode range. However, ESS technologies to maximize power density and energy density simultaneously are not commercially feasible. The use of bi-directional DC-DC converter allows use of multiple energy storage, and the flexible DC-link voltages can enhance the system efficiency and reduce component sizing. This will improve fuel consumption, increase the EV mode range, reduce the total weight, reduce battery initial and life cycle cost, and provide flexibility in system design.

The Influence of Anode Inner Contour on Atmospheric DC Plasma Spraying Process

Directory of Open Access Journals (Sweden)

Kui Wen

2017-01-01

Full Text Available In thermal plasma spraying process, anode nozzle is one of the most important components of plasma torch. Its inner contour controls the characteristics of plasma arc/jet, determining the motion and heating behaviors of the in-flight particles and hence influencing the coating quality. In this study, the effects of anode inner contour, standard cylindrical nozzle, and cone-shaped Laval nozzle with conical shape diverging exit (CSL nozzle on the arc voltage, net power, thermal efficiency, plasma jet characteristics, in-flight particle behaviors, and coating properties have been systematically investigated under atmospheric plasma spraying conditions. The results show that the cylindrical nozzle has a higher arc voltage, net power, and thermal efficiency, as well as the higher plasma temperature and velocity at the torch exit, while the CSL nozzle has a higher measured temperature of plasma jet. The variation trends of the plasma jet characteristics for the two nozzles are comparable under various spraying parameters. The in-flight particle with smaller velocity of CSL nozzle has a higher measured temperature and melting fraction. As a result, the coating density and adhesive strength of CSL nozzle are lower than those of cylindrical nozzle, but the deposition efficiency is greatly improved.

Analysis of processes in DC arc plasma torches for spraying that use air as plasma forming gas

International Nuclear Information System (INIS)

Frolov, V; Ivanov, D; Toropchin, A

2014-01-01

Developed in Saint Petersburg State Polytechnical University technological processes of air-plasma spraying of wear-resistant, regenerating, hardening and decorative coatings used in number of industrial areas are described. The article contains examples of applications of air plasma spraying of coatings as well as results of mathematical modelling of processes in air plasma torches for spraying

Thermal plasma synthesis of transition metal nitrides and alloys

International Nuclear Information System (INIS)

Ronsheim, P.; Christensen, A.N.; Mazza, A.

1981-01-01

Applications of arc plasma processing to high-temperature chemistry of Group V nitrides and Si and Ge alloys are studied. The transition metal nitrides 4f-VN, 4f-NbN, and 4f-TaN are directly synthesized in a dc argon-nitrogen plasma from powders of the metals. A large excess of N 2 is required to form stoichiometric 4f-VN, while the Nb and Ta can only be synthesized with a substoichiometric N content. In a dc argon plasma the alloys V 3 Si, VSi 2 , NbSi 2 , NbGe 2 , Cr 3 Si, and Mo 3 Si are obtained from powder mixtures of the corresponding elements. The compounds are identified by x-ray diffraction patterns and particle shape and size are studied by electron microscopy

Determination of input/output characteristics of full-bridge AC/DC/DC converter for arc welding

OpenAIRE

Stefanov, Goce; Karadzinov, Ljupco; Sarac, Vasilija; Cingoski, Vlatko; Gelev, Saso

2016-01-01

This paper describes the design and practical implementation of AC/DC/DC converter in mode of arc welding. An analysis of the operation of AC/DC/DC converter and its input/output characteristics are determined with computer simulations. The practical part is consisted of AC/DC/DC converter prototype for arc welding with output power of 3 kW and switching frequency of 64 kHz. The operation of AC/DC/DC converter is validated with experimental measurements.

ITAR Free Commercial-of-the-Shelf DC/DC Converter

Science.gov (United States)

Denzinger, Wolfgang; Hintze, Thomas

2014-08-01

A commercial-of-the-shelf (COTS) DC/DC converter for digital space equipment has been developed by ASP under ESA contract with special emphasis on low cost, no use of ITAR listed EEE parts like Mosfets, minimum number of rad-hard digital IC's and a design tolerance against single event effects by appropriate filtering. However, the intention to qualify this discrete converter design for a low cost FM series production was difficult due to the high up-sceening cost of EEE-parts with one lot guarantee and minimum-by. To overcome this problem, in a next step a redesign of the DC/DC converter was performed with all semiconductors like bipolar transistors, rectifiers and zener diodes packaged into hybrids. With this approach it was possible to buy a high number of less expensive wafers or dies from one lot, to perform a lot acceptance test and to integrate the dies into hybrid packages with further up- screening for FM use. The semiconductors have been packaged into three signal hybrids with 44 pins and one power hybrid with 24 pins for the dissipating transistors and rectifiers. The design of the hybrids is such, that all integrated semiconductors can be tested individually. The qualification of four EQM DC/DC converters with different combinations of output voltages has been successfully performed and two FM's have been manufactured and tested.

Study of carbonitriding thermochemical treatment by plasma screen in active with pressures main austenitic stainless steels AISI 409 and AISI 316L; Estudo do tratamento termoquimico de carbonitretacao por plasma em tela ativa com pressoes variaveis nos acos inoxidaveis austenitico AISI 316L e ferririco AISI 409

Energy Technology Data Exchange (ETDEWEB)

Melo, M.S.; Oliveira, A.M.; Leal, V.S.; Sousa, R.R.M. de; Alves Junior, C. [Centro Federal de Educacao Tecnologica do Maranhao (CEFET/MA), Sao Luis, MA (Brazil); Centro Federal de Educacao Tecnologica do Piaui (CEFET/PI), Teresina, PI (Brazil); Universidade Federal do Rio Grande do Norte (DF/UFRN), Natal, RN (Brazil). Dept. de Fisica. Labplasma

2010-07-01

The technique called Active Screen Plasma Nitriding (ASPN) is being used as an alternative once it offers several advantages with respect to conventional DC plasma. In this method, the plasma does not form directly in the sample's surface but on a screen, in such a way that undesired effects such as the edge effect is minimized. Stainless steels present not very satisfactory wearing characteristics. However, plasma carbonitriding has been used as to improve its resistance to wearing due to the formation of a fine surface layer with good properties. In this work, samples of stainless steel AISI 316L and AISI 409 were treated at pressures of 2.5 and 5 mbar. After the treatments they were characterized by microhardness, microscopy and Xray diffraction. Microscopy and hardness analysis showed satisfactory layers and toughness in those steels. (author)

Modelling vacuum arcs : from plasma initiation to surface interactions

International Nuclear Information System (INIS)

Timko, H.

2011-01-01

A better understanding of vacuum arcs is desirable in many of today's 'big science' projects including linear colliders, fusion devices, and satellite systems. For the Compact Linear Collider (CLIC) design, radio-frequency (RF) breakdowns occurring in accelerating cavities influence efficiency optimisation and cost reduction issues. Studying vacuum arcs both theoretically as well as experimentally under well-defined and reproducible direct-current (DC) conditions is the first step towards exploring RF breakdowns. In this thesis, we have studied Cu DC vacuum arcs with a combination of experiments, a particle-in-cell (PIC) model of the arc plasma, and molecular dynamics (MD) simulations of the subsequent surface damaging mechanism. We have also developed the 2D Arc-PIC code and the physics model incorporated in it, especially for the purpose of modelling the plasma initiation in vacuum arcs. Assuming the presence of a field emitter at the cathode initially, we have identified the conditions for plasma formation and have studied the transitions from field emission stage to a fully developed arc. The 'footing' of the plasma is the cathode spot that supplies the arc continuously with particles; the high-density core of the plasma is located above this cathode spot. Our results have shown that once an arc plasma is initiated, and as long as energy is available, the arc is self-maintaining due to the plasma sheath that ensures enhanced field emission and sputtering.The plasma model can already give an estimate on how the time-to-breakdown changes with the neutral evaporation rate, which is yet to be determined by atomistic simulations. Due to the non-linearity of the problem, we have also performed a code-to-code comparison. The reproducibility of plasma behaviour and time-to-breakdown with independent codes increased confidence in the results presented here. Our MD simulations identified high-flux, high-energy ion bombardment as a possible mechanism forming the early

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

Science.gov (United States)

Schwab, J. R.

1979-01-01

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

The effect of dust on electron heating and dc self-bias in hydrogen diluted silane discharges

International Nuclear Information System (INIS)

Schüngel, E; Mohr, S; Iwashita, S; Schulze, J; Czarnetzki, U

2013-01-01

In capacitive hydrogen diluted silane discharges the formation of dust affects plasma processes used, e.g. for thin film solar cell manufacturing. Thus, a basic understanding of the interaction between plasma and dust is required to optimize such processes. We investigate a highly diluted silane discharge experimentally using phase-resolved optical emission spectroscopy to study the electron dynamics, laser light scattering on the dust particles to relate the electron dynamics with the spatial distribution of dust, and current and voltage measurements to characterize the electrical symmetry of the discharge via the dc self-bias. The measurements are performed in single and dual frequency discharges. A mode transition from the α-mode to a bulk drift mode (Ω-mode) is found, if the amount of silane and, thereby, the amount of dust and negative ions is increased. By controlling the electrode temperatures, the dust can be distributed asymmetrically between the electrodes via the thermophoretic force. This affects both the electron heating and the discharge symmetry, i.e. a dc self-bias develops in a single frequency discharge. Using the Electrical Asymmetry Effect (EAE), the dc self-bias can be controlled in dual frequency discharges via the phase angle between the two applied frequencies. The Ω-mode is observed for all phase angles and is explained by a simple model of the electron power dissipation. The model shows that the mode transition is characterized by a phase shift between the applied voltage and the electron conduction current, and that the plasma density profile can be estimated using the measured phase shift. The control interval of the dc self-bias obtained using the EAE will be shifted, if an asymmetric dust distribution is present. However, the width of the interval remains unchanged, because the dust distribution is hardly affected by the phase angle. (paper)

Characterising and modelling extended conducted electromagnetic interference in densely packed DC-DC converter

CSIR Research Space (South Africa)

Grobler, Inus

2013-09-01

Full Text Available . The military specified DC-DC converters are applicable, spanning from 100 W handheld power managers up to 2 kW DC-DC battery chargers. Circuit layout high frequency effects as well as high frequency impedances of the power components were characterised...

A New Sliding Mode Controller for DC/DC Converters in Photovoltaic Systems

Directory of Open Access Journals (Sweden)

M. Sarvi

2013-01-01

Full Text Available DC/DC converters are widely used in many industrial and electrical systems. As DC/DC converters are nonlinear and time-variant systems, the application of linear control techniques for the control of these converters is not suitable. In this paper, a new sliding mode controller is proposed as the indirect control method and compared to a simple direct control method in order to control a buck converter in photovoltaic applications. The solar arrays are dependent power sources with nonlinear voltage-current characteristics under different environmental conditions (insolation and temperature. From this point of view, the DC/DC converter is particularly suitable for the application of the sliding mode control in photovoltaic application, because of its controllable states. Simulations are performed in Matlab/Simulink software. The simulation results are presented for a step change in reference voltage and input voltage as well as step load variations. The simulations results of proposed method are compared with the conventional PID controller. The results show the good performance of the proposed sliding mode controller. The proposed method can be used for the other DC/DC converter.

Disposal of olive mill wastewater with DC arc plasma method.

Science.gov (United States)

Ibrahimoglu, Beycan; Yilmazoglu, M Zeki

2018-07-01

Olive mill wastewater is an industrial waste, generated as a byproduct of olive oil production process and generally contains components such as organic matter, suspended solids, oil, and grease. Although various methods have been developed to achieve the disposal of this industrial wastewater, due to the low cost, the most common disposal application is the passive storage in the lagoons. The main objective of this study is to reduce pollution parameters in olive mill wastewater and draw water to discharge limits by using plasma technology. Plasma-assisted disposal of olive mill wastewater method could be an alternative disposal technique when considering potential utilization of treated water in agricultural areas and economic value of flammable plasma gas which is the byproduct of disposal process. According to the experimental results, the rates of COD (chemical oxygen demand) and BOD (biological oxygen demand) of olive mill wastewater are decreased by 94.42% and 95.37%, respectively. The dissolved oxygen amount is increased from 0.36 to 6.97 mg/l. In addition, plasma gas with high H 2 content and treated water that can be used in agricultural areas for irrigation are obtained from non-dischargeable wastewater. Copyright © 2018 Elsevier Ltd. All rights reserved.

Processamento de Ligas de Níquel com Técnica de Manufatura Aditiva Utilizando Plasma por Arco Transferido

Directory of Open Access Journals (Sweden)

Eduardo André Alberti

2015-06-01

Full Text Available ResumoA manufatura aditiva é um processo utilizado para a construção e reparos de peças que possuem geometria complexa ou que necessitem de gradiente de propriedades. Nessa técnica múltiplas camadas são depositadas para a construção da geometria do componente. O sucesso desse procedimento depende de fatores como a técnica de deposição, parâmetros, liga a ser depositada e condições da deposição, como temperatura e atmosfera protetora. Neste estudo, o potencial da técnica de Plasma por arco transferido para manufatura aditiva foi avaliado produzindo “paredes finas”, construídas a partir da sobreposição de cordões. Foram utilizadas duas ligas a base de níquel, uma endurecida por precipitação e outra endurecida por solução sólida. Durante os trabalhos, foram selecionados os parâmetros de processamentos, incluindo a avaliação do efeito do pré-aquecimento a 300°C. Resultados mostraram que a composição química da liga influencia a geometria da parede construída assim como a utilização de pré-aquecimento. Estruturas de solidificação exibindo dendritas refinadas com crescimento epitaxial entre camadas são identificadas. Entretanto, as características da liga determinam o perfil de dureza ao longo da seção transversal, sendo a liga endurecida por precipitação influenciada pelos ciclos térmicos de deposição e a liga endurecida por solução sólida pela diluição com o substrato. Em qualquer dos casos é recomendado a aplicação de tratamento térmico pós-soldagem para uniformização das propriedades.

Very High Frequency Half Bridge DC/DC Converter

DEFF Research Database (Denmark)

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

2014-01-01

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

Sheppard-Taylor Isolated High Boost DC-DC Converter

DEFF Research Database (Denmark)

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

2017-01-01

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

Recent progress in thin film processing by magnetron sputtering with plasma diagnostics

International Nuclear Information System (INIS)

Han, Jeon G

2009-01-01

The precise control of the structure and related properties becomes crucial for sophisticated applications of thin films deposited by magnetron sputtering in emerging industries including the flat panel display, digital electronics and nano- and bio-industries. The film structure is closely related to the total energy delivered to the substrate surface for nucleation and growth during all kinds of thin film processes, including magnetron sputtering. Therefore, the energy delivered to the surface for nucleation and growth during magnetron sputtering should be measured and analysed by integrated diagnostics of the plasma parameters which are closely associated with the process parameters and other external process conditions. This paper reviews the background of thin film nucleation and growth, the status of magnetron sputtering technology and the progress of plasma diagnostics for plasma processing. The evolution of the microstructure during magnetron sputtering is then discussed with respect to the change in the process variables in terms of the plasma parameters along with empirical data of the integrated plasma diagnostics for various magnetron sputtering conditions with conventional dc, pulsed dc and high power pulsed dc sputtering modes. Among the major energy terms to be discussed are the temperature change in the top surface region and the energies of ions and neutral species. (topical review)

Análisis multielemental secuencial de aleaciones mediante plasma de argón generado por acoplamiento inductivo de radiofrecuencia

OpenAIRE

Farías de Funes, Silvia

1996-01-01

En el presente trabajo se describe la caracterización espectroscópica y analítica de un espectrómetro óptico constituido por el acoplamiento de una fuente de plasma inductivo de argón (IPC) y un monocromador programable de alta resolución, aplicable a la determinación secuencial de Mg, Mn, Cr, Mo en aleaciones de aluminio y de base Cu-Ni. Después de una discusión general sobre las características fundamentales del dispositivo instrumental empleado, se consideran aspectos básicos relacionados ...

A DC-DC Conversion Powering Scheme for the CMS Phase-1 Pixel Upgrade

CERN Document Server

Feld, Lutz Werner; Marcel Friedrichs; Richard Hensch; Karpinski, Waclaw; Klein, Katja; Sammet, Jan Domenik; Wlochal, Michael

2012-01-01

The powering scheme of the CMS pixel detector will be described, and the performance of prototype DC-DC buck converters will be presented, including power efficiency, system tests with DC-DC converters and pixel modules, thermal management, reliability at low temperature, and studies of potential frequency locking betwe...

Time-dependent plasma behavior triggered by a pulsed electron gun under conditions of beam-plasma-discharge

International Nuclear Information System (INIS)

Szuszczewicz, E.P.; Lin, C.S.

1982-01-01

This chapter reports on experiments whose purpose was to simulate spaceborne applications of energetic electron guns while exploring the ''in situ'' diagnostics of time-dependent beam-plasma behavior under pulsed electron gun conditions. Beam-plasma-discharge (BPD), the BPD afterglow that exists after gun-pulse termination, and the plasma decay process are considered. It is concluded that there is a rapid enhancement in plasma density as the gas turns on; that during the pulse-ON time a quasi-steady-state BPD can be maintained with characteristics identical with its dc counterpart; that in the period immediately following gun-pulse termination the plasma loss process is dominated by cross-field radial diffusion; and that the afterglow plasma is within + or -10% of being an isodensity contour

Study on the Control Algorithm of Two-Stage DC-DC Converter for Electric Vehicles

Directory of Open Access Journals (Sweden)

Changhao Piao

2014-01-01

Full Text Available The fast response, high efficiency, and good reliability are very important characteristics to electric vehicles (EVs dc/dc converters. Two-stage dc-dc converter is a kind of dc-dc topologies that can offer those characteristics to EVs. Presently, nonlinear control is an active area of research in the field of the control algorithm of dc-dc converters. However, very few papers research on two-stage converter for EVs. In this paper, a fixed switching frequency sliding mode (FSFSM controller and double-integral sliding mode (DISM controller for two-stage dc-dc converter are proposed. And a conventional linear control (lag is chosen as the comparison. The performances of the proposed FSFSM controller are compared with those obtained by the lag controller. In consequence, the satisfactory simulation and experiment results show that the FSFSM controller is capable of offering good large-signal operations with fast dynamical responses to the converter. At last, some other simulation results are presented to prove that the DISM controller is a promising method for the converter to eliminate the steady-state error.

Some preliminary views of plasma interaction: electromagnetic-launch systems

International Nuclear Information System (INIS)

Buckingham, A.C.; Hawke, R.S.

1982-01-01

This discussion outlines a few areas of fundamental research which appear vital for progress in developing advanced propulsion concepts using dc railgun thrusters. We have placed emphasis on the following: (1) dense plasma and high current density influences on changes in microstructure and properties of conventional rail conductors such as Cu, Al, and W alloys or composites; (2) the influences described in (1) on more advanced high temperature, microstrain resistant, materials such as amorphous tungsten; (3) location, description and temporal evolution of current, magnetic field, and losses during intense plasma-current field interactions with conductors; and (4) composite materials and sequentially sectioned structures for more efficient EM dc launcher configuration

Regulation of DC development and DC-mediated T-cell immunity via CISH

OpenAIRE

Miah, Mohammad Alam; Bae, Yong-Soo

2013-01-01

Cytokine inducible SH2-containing protein (CISH) plays a crucial role in type 1 dendritic cell (DC) development as well as in the DC-mediated activation of cytotoxic T lymphocytes (CTLs). CISH expression at late DC developmental stages shuts down the proliferation of DC progenitors by negatively regulating signal transducer and activator of transcription 5 (STAT5) and facilitates the differentiation of DCs into potent stimulators of CTLs.

Regulation of DC development and DC-mediated T-cell immunity via CISH.

Science.gov (United States)

Miah, Mohammad Alam; Bae, Yong-Soo

2013-03-01

Cytokine inducible SH2-containing protein (CISH) plays a crucial role in type 1 dendritic cell (DC) development as well as in the DC-mediated activation of cytotoxic T lymphocytes (CTLs). CISH expression at late DC developmental stages shuts down the proliferation of DC progenitors by negatively regulating signal transducer and activator of transcription 5 (STAT5) and facilitates the differentiation of DCs into potent stimulators of CTLs.

Nonthermal Radiation Processes in Interplanetary Plasmas

Science.gov (United States)

Chian, A. C. L.

1990-11-01

RESUMEN. En la interacci6n de haces de electrones energeticos con plasmas interplanetarios, se excitan ondas intensas de Langmuir debido a inestabilidad del haz de plasma. Las ondas Langmuir a su vez interaccio nan con fluctuaciones de densidad de baja frecuencia para producir radiaciones. Si la longitud de las ondas de Langmujr exceden las condicio nes del umbral, se puede efectuar la conversi5n de modo no lineal a on- das electromagneticas a traves de inestabilidades parametricas. As se puede excitar en un plasma inestabilidades parametricas electromagneticas impulsadas por ondas intensas de Langmuir: (1) inestabilidades de decaimiento/fusi5n electromagnetica impulsadas por una bomba de Lang- muir que viaja; (2) inestabilidades dobles electromagneticas de decai- miento/fusi5n impulsadas por dos bombas de Langrnuir directamente opues- tas; y (3) inestabilidades de dos corrientes oscilatorias electromagne- ticas impulsadas por dos bombas de Langmuir de corrientes contrarias. Se concluye que las inestabilidades parametricas electromagneticas in- ducidas por las ondas de Langmuir son las fuentes posibles de radiacio- nes no termicas en plasmas interplanetarios. ABSTRACT: Nonthermal radio emissions near the local electron plasma frequency have been detected in various regions of interplanetary plasmas: solar wind, upstream of planetary bow shock, and heliopause. Energetic electron beams accelerated by solar flares, planetary bow shocks, and the terminal shock of heliosphere provide the energy source for these radio emissions. Thus, it is expected that similar nonthermal radiation processes may be responsible for the generation of these radio emissions. As energetic electron beams interact with interplanetary plasmas, intense Langmuir waves are excited due to a beam-plasma instability. The Langmuir waves then interact with low-frequency density fluctuations to produce radiations near the local electron plasma frequency. If Langmuir waves are of sufficiently large

Treatment of simulated INEL buried wastes using a graphite electrode DC arc furnace

International Nuclear Information System (INIS)

Surma, J.E.; Lawrence, W.E.; Titus, C.H.; Wittle, J.K.; Hamilton, R.A.; Cohn, D.R.; Rhea, D.; Thomas, P.; Woskov, P.P.

1994-08-01

A program has been established under the auspices of the Department of Energy (DOE), Office of Technology Development (OTD), to develop the graphite electrode DC arc technology for the application of treating buried heterogenous solid wastes. A three way open-quotes National Laboratory-University-Industryclose quotes partnership was formed to develop this technology in the most timely and cost effective manner. This program is presently testing a newly fabricated pilot-scale DC arc furnace with associated diagnostics at the Plasma Fusion Center at the Massachusetts Institute of Technology. Initial testing in a smaller engineering scale furnace has established the viability of this technology for the treatment of solid heterogeneous wastes. Two diagnostic tools were developed under this program which support the evaluation of the DC arc technology. The diagnostics provide for both spatially resolved temperature measurements within the furnace and real time monitoring of the furnace metal emissions

The density and velocity of plasma bullets propagating along one dielectric tube

Directory of Open Access Journals (Sweden)

Longfei Ji

2015-08-01

Full Text Available This study shows that the propagation of plasma bullets along one dielectric tube is strongly affected by many discharge parameters, such as the waveform of applied voltage (AC or pulsed DC, peak voltage, He flow rate, and the frequency of AC voltage. Analysis indicates that the density and velocity of plasma bullets are mainly determined by the electric field at the front of plasma bullets. These discharge parameters may significantly influence the distribution of plasma potential along the tube, thus control the electric field at the front of plasma bullets and their propagation. An increase in the pulsed DC voltage with its rise time of <40-50 ns can lead to an obvious improvement in the electric field at the front of plasma bullets, resulting in generation of a plasma in the high density gas and a fast propagation of plasma bullets. He flowing through the tube can contribute to the surface diffusion of charged species, and greatly increase the electric field at the front of plasma bullets. During the propagation of plasma bullets, their density is decreased due to the surface recombination of charged species, such as electrons and ions.

The Effect of dcEFs on migration behavior of A549 cells and Integrin beta1 expression

Directory of Open Access Journals (Sweden)

Yunjie WANG

2008-04-01

Full Text Available Background and objective The effect of direct-current electric fields (dcEFs on cells attracted extensive attention. Moreover the metastasis and its potential are considered to be related to dcEFs. The aim is to study the effect of dcEFs on migration behavior of A549 cells, Integrin ?1 and its signal pathways. Methods According to exposure to 5 V/cm dcEFs or not and the time of exposure, the A549 cells were divided into 4 groups. Images were taken per 5 min within 2 h to recode the migration of the cells. The data of results were analyzed statistically. Results Most of A549cells exposed to the dcEFs aligned and elongated perpendicularly to the electric field lines and migrated to the cathode continually during 2 h. On the contrary, cells unexposed to dcEFs showed slightly random movements. Immunofluorescence showed that Integrin ?1 on plasma membrane polarized to the cathode of the dcEFs. Western blot showed that Integrin beta1 downstream signal pathways p-FAK and p-ERK were overexpressed in the dcEFs. Conclusion A549 cells have a galvanotatic feature of cathodal directed migration while exposed to the dcEFs. The polarization of Integrin beta1 and the promotion of its downstream signal pathways may play an important roles in the galvanotaxis of A549 cells.

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

International Nuclear Information System (INIS)

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

2009-01-01

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

Synthesis by plasma of halogenated poly anilines; Sintesis por plasma de polianilinas halogenadas

Energy Technology Data Exchange (ETDEWEB)

Enriquez, M.A.; Olayo, M.G.; Cruz, G.J. [Facultad de Quimica, UAEM, 50000 Toluca, Estado de Mexico (Mexico)

2002-07-01

In this work polymerization by plasma of aniline with iodine and chlorine bonded chemically to the aniline ring were realized. The results of the synthesis and characterizations are compared with those ones obtained starting from the poly aniline synthesis (P An) doped with iodine, where the dopant was aggregated in the moment of the polymerization. The objective is to study the dopant behavior in the synthesis by plasma in function of the properties of these polymers. (Author)

Synthesis of semiconductor polymers by inductive plasma; Sintesis de polimeros semiconductores por plasmas inductivos

Energy Technology Data Exchange (ETDEWEB)

Fernandez, G.; Cruz, G.; Olayo, M.G. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico); Morales, J. [UAM-I, 09340 Mexico D.F. (Mexico)

2003-07-01

When carrying out the synthesis of semiconductor polymers by plasma it is important to consider the electric arrangement of the discharge since this it influences in the distribution of the energy of the particles in the reactor. The main electric arrangements in those that are developed the brightness discharges of radio frequency are resistive, capacitive and inductive. In the Laboratory of Materials processing by plasma of the ININ its have been worked different synthesis of polymers with resistive arrangements with good results. In this work the results of the synthesis and characterization of poly aniline and chlorate polyethylene by inductive plasma are presented. (Author)

Influence of an External DC Electric Current on Plasma Cleaning Rate: an Application on the Enlarged Plasma-Surface Theory

International Nuclear Information System (INIS)

Xaplanteris, Constantine L.; Filippaki, Eleni D.

2013-01-01

During the last decades many researchers have been occupied with other plasma applications apart from the big challenge which the thermonuclear fusion poses. Many experiments have been carried out on the plasma behavior in contact with a solid surface; when the surface material consists of chemical compounds (e.g. oxides of metals), then the plasma chemistry takes place. The present paper contains the final experimental and theoretical work of Plasma Laboratory at “Demokritos , which consists of an elaboration of plasma sheath parameters adapted to experimental conditions, a suitable choice of plasma gases (either H 2 or N 2 ), and an electric potential current enforcement on objects. Additionally, a brief theory is given to explain the results, with a short reference to both boundary phenomena in thermonuclear reactors and low pressure plasma of glow discharges, so as to reveal the similarities and differences of these two cases. An extensive examination of the treated objects by X-ray diffraction method (XRD) gives results in agreement with the theoretical predictions. Using this improvement on plasma restoration system, (a combination of electric current on metallic object into suitable plasma), it is shown that better results can be achieved on the cleaning and conservation of archaeological objects. (plasma technology)

Elimination of output voltage oscillations in DC-DC converter using PWM with PI controller

Directory of Open Access Journals (Sweden)

Sreenivasappa Veeranna Bhupasandra

2010-01-01

Full Text Available In this paper the SIMULINK model of a PWM controlled DC-DC converter is modeled using switching function concept to control the speed of the DC motor. The presence of the voltage oscillation cycles due to higher switching frequency in the DC-DC converter is identified. The effect of these oscillations on the output voltage of the converter, Armature current, Developed torque and Speed of the DC motor is analyzed. In order to minimize the oscillation cycles the PI controller is proposed in the PWM controller.

Plasma Spraying of Copper by Hybrid Water-Gas DC Arc Plasma Torch

Czech Academy of Sciences Publication Activity Database

Kavka, Tetyana; Matějíček, Jiří; Ctibor, Pavel; Mašláni, Alan; Hrabovský, Milan

2011-01-01

Roč. 20, č. 4 (2011), s. 760-774 ISSN 1059-9630 R&D Projects: GA ČR GAP205/11/2070 Institutional research plan: CEZ:AV0Z20430508 Keywords : copper coatings * hybrid water-gas torch * metallic particle oxidation Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.812, year: 2011 http://www.springerlink.com/content/78n3736855261197/fulltext.pdf

Analysis of high voltage step-up nonisolated DC-DC boost converters

Science.gov (United States)

Alisson Alencar Freitas, Antônio; Lessa Tofoli, Fernando; Junior, Edilson Mineiro Sá; Daher, Sergio; Antunes, Fernando Luiz Marcelo

2016-05-01

A high voltage step-up nonisolated DC-DC converter based on coupled inductors suitable to photovoltaic (PV) systems applications is proposed in this paper. Considering that numerous approaches exist to extend the voltage conversion ratio of DC-DC converters that do not use transformers, a detailed comparison is also presented among the proposed converter and other popular topologies such as the conventional boost converter and the quadratic boost converter. The qualitative analysis of the coupled-inductor-based topology is developed so that a design procedure can be obtained, from which an experimental prototype is implemented to validate the theoretical assumptions.

Common mode noise in three-level DC-DC converters

CSIR Research Space (South Africa)

Grobler, Inus

2009-09-01

Full Text Available that three-level buck DC-DC converters in general generate much lower common mode currents than conventional two-level buck converters. Further, reductions in common mode currents are achieved by using the improved three-level topologies that have been...

Influence of non-equilibrium effects on plasma property functions in hybrid water-argon plasma torch

Czech Academy of Sciences Publication Activity Database

Křenek, Petr; Hrabovský, Milan

2010-01-01

Roč. 14, 1-2 (2010), s. 95-100 ISSN 1093-3611. [European High Temperature Plasma Processes (HTPP)/10th./. Patras (Patras University), 07.07.2008-11.07.2008] R&D Projects: GA ČR GA202/08/1084 Institutional research plan: CEZ:AV0Z20430508 Keywords : Thermal plasma * material properties * non-equlibrium phenomena * dc arc torch Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.189, year: 2010 http://www.begellhouse.com/journals/57d172397126f956,227c67f42b79464a,5bbc4c7760b4b6cb.html

Analysis and Design of Bi-Directional DC-DC Converter in the Extended Run Time DC UPS System Based on Fuel Cell and Supercapacitor

DEFF Research Database (Denmark)

Zhang, Zhe; Thomsen, Ole Cornelius; Andersen, Michael A. E.

2009-01-01

Abstract-In this paper, an extended run time DC UPS system structure with fuel cell and supercapacitor is investigated. A wide input range bi-directional dc-dc converter is described along with the phase-shift modulation scheme and phase-shift with duty cycle control, in different modes. The deli......Abstract-In this paper, an extended run time DC UPS system structure with fuel cell and supercapacitor is investigated. A wide input range bi-directional dc-dc converter is described along with the phase-shift modulation scheme and phase-shift with duty cycle control, in different modes...

DC-DC power converter research for Orbiter/Station power exchange

Science.gov (United States)

Ehsani, M.

1993-01-01

This project was to produce innovative DC-DC power converter concepts which are appropriate for the power exchange between the Orbiter and the Space Station Freedom (SSF). The new converters must interface three regulated power buses on SSF, which are at different voltages, with three fuel cell power buses on the Orbiter which can be at different voltages and should be tracked independently. Power exchange is to be bi-directional between the SSF and the Orbiter. The new converters must satisfy the above operational requirements with better weight, volume, efficiency, and reliability than is available from the present conventional technology. Two families of zero current DC-DC converters were developed and successfully adapted to this application. Most of the converters developed are new and are presented.

Experimental Investigation on the Characteristics of Sliding Discharge Plasma Aerodynamic Actuation

International Nuclear Information System (INIS)

Song Huimin; Zhang Qiaogen; Li Yinghong; Jia Min; Wu Yun

2011-01-01

A new electrical discharge called sliding discharge was developed to generate plasma aerodynamic actuation for flow control. A microsecond-pulse high voltage with a DC component was used to energize a three-electrode actuator to generate sliding discharge. The characteristics of plasma aerodynamic actuation by sliding discharge were experimentally investigated. Discharge morphology shows that sliding discharge is formed when energized by properly adjusting microsecond-pulse and DC voltage. Compared to dielectric barrier discharge (DBD), the plasma extension of sliding discharge is quasi-diffusive and stable but longer and more intensive. Results from particle image velocimetry (PIV) test indicate that plasma aerodynamic actuation by sliding discharge can induce a ‘starting vortex’ and a quasi-steady ‘near-wall jet’. Body force induced by plasma aerodynamic actuation is about the order of mN, which is stronger than that induced by single DBD. It is inferred that microsecond-pulse sliding discharge may be more effective to generate large-scale plasma aerodynamic actuation, which is very promising for improving aircraft aerodynamic characteristics and propulsion efficiency.

Experimental Investigation on the Characteristics of Sliding Discharge Plasma Aerodynamic Actuation

Science.gov (United States)

Song, Huimin; Li, Yinghong; Zhang, Qiaogen; Jia, Min; Wu, Yun

2011-10-01

A new electrical discharge called sliding discharge was developed to generate plasma aerodynamic actuation for flow control. A microsecond-pulse high voltage with a DC component was used to energize a three-electrode actuator to generate sliding discharge. The characteristics of plasma aerodynamic actuation by sliding discharge were experimentally investigated. Discharge morphology shows that sliding discharge is formed when energized by properly adjusting microsecond-pulse and DC voltage. Compared to dielectric barrier discharge (DBD), the plasma extension of sliding discharge is quasi-diffusive and stable but longer and more intensive. Results from particle image velocimetry (PIV) test indicate that plasma aerodynamic actuation by sliding discharge can induce a ‘starting vortex’ and a quasi-steady ‘near-wall jet’. Body force induced by plasma aerodynamic actuation is about the order of mN, which is stronger than that induced by single DBD. It is inferred that microsecond-pulse sliding discharge may be more effective to generate large-scale plasma aerodynamic actuation, which is very promising for improving aircraft aerodynamic characteristics and propulsion efficiency.

Plasma diagnostics by means of electric probes; Diagnostico del plasma por medio de sondas electricas

Energy Technology Data Exchange (ETDEWEB)

Colunga S, S

1991-04-15

In this work a summary of the classical theoretical models to interpret the characteristic curve of a Langmuir electric probe placed in a plasma without magnetic field and with the one is made. The methodology for the electron temperature calculation and the density of the plasma in both cases is given, starting from the characteristic curve of the probe, as well as the approaches for the correct application of this diagnostic method of the plasma. (Author)

Sliding-mode control of single input multiple output DC-DC converter

Science.gov (United States)

Zhang, Libo; Sun, Yihan; Luo, Tiejian; Wan, Qiyang

2016-10-01

Various voltage levels are required in the vehicle mounted power system. A conventional solution is to utilize an independent multiple output DC-DC converter whose cost is high and control scheme is complicated. In this paper, we design a novel SIMO DC-DC converter with sliding mode controller. The proposed converter can boost the voltage of a low-voltage input power source to a controllable high-voltage DC bus and middle-voltage output terminals, which endow the converter with characteristics of simple structure, low cost, and convenient control. In addition, the sliding mode control (SMC) technique applied in our converter can enhance the performances of a certain SIMO DC-DC converter topology. The high-voltage DC bus can be regarded as the main power source to the high-voltage facility of the vehicle mounted power system, and the middle-voltage output terminals can supply power to the low-voltage equipment on an automobile. In the respect of control algorithm, it is the first time to propose the SMC-PID (Proportion Integration Differentiation) control algorithm, in which the SMC algorithm is utilized and the PID control is attended to the conventional SMC algorithm. The PID control increases the dynamic ability of the SMC algorithm by establishing the corresponding SMC surface and introducing the attached integral of voltage error, which endow the sliding-control system with excellent dynamic performance. At last, we established the MATLAB/SIMULINK simulation model, tested performance of the system, and built the hardware prototype based on Digital Signal Processor (DSP). Results show that the sliding mode control is able to track a required trajectory, which has robustness against the uncertainties and disturbances.

Space plasma branch at NRL

Science.gov (United States)

The Naval Research Laboratory (Washington, D.C.) formed the Space Plasma Branch within its Plasma Physics Division on July 1. Vithal Patel, former Program Director of Magnetospheric Physics, National Science Foundation, also joined NRL on the same date as Associate Superintendent of the Plasma Physics Division. Barret Ripin is head of the newly organized branch. The Space Plasma branch will do basic and applied space plasma research using a multidisciplinary approach. It consolidates traditional rocket and satellite space experiments, space plasma theory and computation, with laboratory space-related experiments. About 40 research scientists, postdoctoral fellows, engineers, and technicians are divided among its five sections. The Theory and Computation sections are led by Joseph Huba and Joel Fedder, the Space Experiments section is led by Paul Rodriguez, and the Pharos Laser Facility and Laser Experiments sections are headed by Charles Manka and Jacob Grun.

Y-Source Boost DC/DC Converter for Distributed Generation

DEFF Research Database (Denmark)

Siwakoti, Yam P.; Loh, Poh Chiang; Blaabjerg, Frede

2015-01-01

This paper introduces a versatile Y-source boost dc/dc converter intended for distributed power generation, where high gain is often demanded. The proposed converter uses a Y-source impedance network realized with a tightly coupled three-winding inductor for high voltage boosting that is presently...

SUBCONTRACT REPORT: DC-DC Converter for Fuel Cell and Hybrid Vehicles

Energy Technology Data Exchange (ETDEWEB)

Marlino, Laura D [ORNL; Zhu, Lizhi [Ballard Power Systems/Siemens VDO

2007-07-01

The goal of this project is to develop and fabricate a 5kW dc-dc converter with a baseline 14V output capability for fuel cell and hybrid vehicles. The major objectives for this dc-dc converter technology are to meet: Higher efficiency (92%); High coolant temperature,e capability (105 C); High reliability (15 Years/150,000miles); Smaller volume (5L); Lower weight (6kg); and Lower cost ($75/kW). The key technical challenge for these converters is the 105 C coolant temperatures. The power switches and magnetics must be designed to sustain these operating temperatures reliably, without a large cost/mass/volume penalty.

Multi-level cascaded DC/DC converters for PV applications

Directory of Open Access Journals (Sweden)

Ahmed A.A. Hafez

2015-12-01

Full Text Available A robust multi-level cascaded DC/DC system for Photovoltaic (PV application is advised in this article. There are three PV generators, each is coupled to a half-bridge buck cell. Each PV-generator–buck-converter channel is controlled such that maximum power is captured independently under different irradiation and temperature levels. The system operation under normal and abnormal conditions was comprehensively investigated. Internal Model Control (IMC technique was adopted for tuning the controllers. An elaborate switching modulation strategy was used to reduce the current ripple and inductor size, while maintaining high efficiency. Annotative, simple and robust remedial strategies were proposed to mitigate different anticipated faults. Comprehensive simulation results in Matlab environment were illustrated for corroborating the performance of the advised cascaded DC/DC system under normal/abnormal conditions. The proposed system enjoys the merits of independency, reduced volumetric dimensions and improved efficiency. Furthermore, the system is inherently fault-tolerant.

Development of a DC-DC conversion powering scheme for the CMS Phase-1 pixel upgrade

CERN Document Server

Feld, Lutz Werner; Karpinski, Waclaw; Klein, Katja; Lipinski, Martin; Preuten, Marius; Max Rauch; Rittich, David Michael; Sammet, Jan Domenik; Wlochal, Michael

2014-01-01

A novel powering scheme based on the DC-DC conversion technique will be exploited to power the CMS Phase-1 pixel detector. DC-DC buck converters for the CMS pixel project have been developed, based on the AMIS5 ASIC designed by CERN. The powering system of the Phase-1 pixel detector is described and the performance of the converter prototypes is detailed, including power efficiency, stability of the output voltage, shielding, and thermal management. Results from a test of the magnetic field tolerance of the DC-DC converters are reported. System tests with pixel modules using many components of the future pixel barrel system are summarized. Finally first impressions from a pre-series of 200 DC-DC converters are presented.

High-density plasma etching characteristics of indium-gallium-zinc oxide thin films in CF4/Ar plasma

International Nuclear Information System (INIS)

Joo, Young-Hee; Kim, Chang-Il

2015-01-01

We investigated the etching process of indium-gallium-zinc oxide (IGZO) thin films in an inductively coupled plasma system. The dry etching characteristics of the IGZO thin films were studied by varying the CF 4 /Ar gas mixing ratio, RF power, DC-bias voltage, and process pressure. We determined the following optimized process conditions: an RF power of 700 W, a DC-bias voltage of − 150 V, and a process pressure of 2 Pa. A maximum etch rate of 25.63 nm/min for the IGZO thin films was achieved in a plasma with CF 4 /Ar(= 25:75), and the selectivity of IGZO to Al and TiN was found to be 1.3 and 0.7, respectively. We determined the ionic composition of the CF 4 /Ar plasma using optical emission spectroscopy. Analysis of chemical reactions at the IGZO thin film surfaces was performed using X-ray photoelectron spectroscopy. - Highlights: • IGZO thin film was etched by CF 4 /Ar plasma as a function of gas mixing ratio. • IGZO bonds were broken Ar + sputtering and then reacted with the C-F x radicals. • The physical sputtering is dominant in etch control compared with chemical etching

Auxiliary resonant DC tank converter

Science.gov (United States)

Peng, Fang Z.

2000-01-01

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

Performance Test of the Microwave Ion Source with the Multi-layer DC Break

International Nuclear Information System (INIS)

Kim, Dae Il; Kwon, Hyeok Jung; Kim, Han Sung; Seol, Kyung Tae; Cho, Yong Sub

2012-01-01

A microwave proton source has been developed as a proton injector for the 100-MeV proton linac of the PEFP (Proton Engineering Frontier Project). On microwave ion source, the high voltage for the beam extraction is applied to the plasma chamber, also to the microwave components such as a 2.45GHz magnetron, a 3-stub tuner, waveguides. If microwave components can be installed on ground side, the microwave ion source can be operated and maintained easily. For the purpose, the multi-layer DC break has been developed. A multi-layer insulation has the arrangement of conductors and insulators as shown in the Fig. 1. For the purpose of stable operation as the multi-layer DC break, we checked the radiation of the insulator depending on materials and high voltage test of a fabricated multi-layer insulation. In this report, the details of performance test of the multi-layer DC break will be presented

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

Science.gov (United States)

Gruber, Robert P.; Gott, Robert W.

1991-01-01

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

Spectroscopic diagnostics of industrial plasmas

International Nuclear Information System (INIS)

Joshi, N.K.

2004-01-01

Plasmas play key role in modern industry and are being used for processing micro electronic circuits to the destruction of toxic waste. Characterization of industrial plasmas which includes both 'thermal plasmas' and non-equilibrium plasmas or 'cold plasmas' in industrial environment offers quite a challenge. Numerous diagnostic techniques have been developed for the measurement of these partially ionized plasma and/or particulate parameters. The 'simple' non-invasive spectroscopic methods for characterization of industrial plasmas will be discussed in detail in this paper. The excitation temperature in thermal (DC/RF) plasma jets has been determined using atomic Boltzmann technique. The central axis temperature of thermal plasma jets in a spray torch can be determined using modified atomic Boltzmann technique with out using Abel inversion. The Stark broadening of H β and Ar-I (430 nm) lines have been used to determine the electron number density in thermal plasma jets. In low-pressure non-equilibrium argon plasma, electron temperature has been measured using the Corona model from the ratio of line intensities of atomic and ionic transitions. (author)

Development of a green mode DC/DC converter available to portable nuclear instrument

International Nuclear Information System (INIS)

Gao Feiyan; Wu Longxiong; Tan Wei; Tang Yaogeng

2010-01-01

A green mode DC/DC converter was developed which suitable to the portable nuclear instrument which is powered by battery and is sometime at stand-by mode. Some updated control approaches such as pseudo-resonant type power supply control and synchronous rectification were adopted to makethe DC/DC converter operate with low power consumption and high efficiency. The test results the battery can be prolonged with this converter. (authors)

Uso tradicional de plantas medicinales en mercados de Bogot?, D.C

OpenAIRE

Giraldo Quintero, Sara Emilia; Bernal Lizaraz?, Mar?a Consuelo; Morales Robayo, Adriana; Pardo Lobo, Alesdy Zuled; Gamba Molano, Leopoldo

2015-01-01

Objetivo.Describir el uso tradicional de 26 plantas, identificando la droga vegetal, su preparaci?n y administraci?n, los fines medicinales para los que se recomiendan y posibles pr?cticas de uso inadecuado. Materiales y m?todos. Se aplicaron 16 entrevistas semiestructuradas a vendedores de plantas medicinales en 8 plazas de mercado de la ciudad de Bogot?, D.C. Adicionalmente se realiz? la identificaci?n taxon?mica de las plantas con mayor reporte por parte de los vendedores y su uso tradicio...

Demonstration of Plasma Assisted Waste Conversion to Gas

Data.gov (United States)

National Aeronautics and Space Administration — The goal is to demonstrate high fidelity mission waste simulant conversion with a proprietary DC plasma torch, a different approach from industry which uses higher...

Weathering resistance of thin plasma polymer films on pre-coated steel =

Science.gov (United States)

Serra, Ricardo Gil Henriques

O trabalho apresentado teve origem no projecto de investigacao “Tailored Thin Plasma Polymers Films for Surface Engineering of Coil Coated Steel”, financiado pelo Programa Europeu ECSC Steel Research. Sistemas de aco galvanizado pre-pintado em banda a base de poliester e poliuretano foram submetidos a um processo de polimerizacao por plasma onde um filme fino foi depositado de modo a modificar as propriedades de superficie. Foram usados reactores de catodo oco, microondas e radio frequencia para a deposicao do polimero fino. Os sistemas preparados foram analisados de modo a verificar a influencia do processo de polimerizacao por plasma na alteracao das propriedades barreira dos sistemas pre-pintados em banda. Foi estudado o efeito dos diferentes passos do processo de polimerizacao por plasma, bem como o efeito de diferentes variaveis operatorias. A mistura precursora foi variada de modo a modificar as propriedades da superficie de modo a poder vir a obter maior hidrofobicidade, maior resistencia a marcas digitais, bem como maior facilidade de limpeza. Os testes foram conduzidos em solucao de NaCl 0,5 M. Para o trabalho foram usadas tecnicas de analise da morfologia da superficie como Microscopia de Forca Atomica e Microscopia Electronica de Varrimento. As propriedades electroquimicas dos sistemas foram estudadas por Espectroscopia de Impedancia Electroquimica. A estrutura dos filmes gerados no processo de polimerizacao por plasma foi caracterizada por Microscopia de Transmissao Electronica. A modificacao das propriedades opticas devido ao processo de polimerizacao por plasma foi tambem obtida.

A Dual-Buck–Boost AC/DC Converter for DC Nanogrid With Three Terminal Outputs

DEFF Research Database (Denmark)

Wu, Weimin; Wang, Houqing; Liu, Yuan

2017-01-01

Due to the widely used dc characterized loads and more distributed power generation sources, the dc nanogrid becomes more and more popular, and it is seen as an alternative to the ac grid. For safety considerations, the dc nanogrid should provide reliable grounding for the residential loads...... such as the low-voltage ac power system. There are three typical grounding configurations for a dc nanogrid: the united grounding, the unidirectional grounding, and the virtual isolated grounding. Each grounding configuration has its own specifications to ac/dc converters. In this paper, a dual-buck-boost ac/dc...... converter for use in the united-grounding-configuration-based dc nanogrid with three terminal outputs is proposed. The working principle of this converter is presented in detail through analyzing the equivalent circuits. Experiments are carried out to verify the theoretical analysis....

DESIGN OPTIMIZATION OF RESONANT DC-DC CONVERTERS

OpenAIRE

Belqasem Aljafari

2016-01-01

Resonant DC/DC converters are the class of converters, which have L-C resonant tank serving as a major part of the power conversion process. The fundamental concept of the resonant converter is that the circulating energy in an L-C resonant circuit is manageable by changing the operating frequency, and therefore the converter can condition the input power to the desired output voltage. The development in power conversion technology is steady demand for high power efficiency and high power den...

Study of short atmospheric pressure dc glow microdischarge in air

Science.gov (United States)

Kudryavtsev, Anatoly; Bogdanov, Eugene; Chirtsov, Alexander; Emelin, Sergey

2011-10-01

The results of experiments and simulations of short (without positive column) atmospheric pressure dc glow discharge in air are presented. We used metal steel electrodes with a gap of 5-100 microns. The experimental voltage-current characteristic's (VAC) have a constant or slightly increasing form at low gap. The most stable microdischarges were burning with a flat cathode and rounded anode, when the length of the discharge is automatically established near the minimum of the Paschen curve by changing their binding on the anode. In this case microdischarge was stable and it had growing VAC. For simulations we used 2D fluid model with kinetic description of electrons. We solved the balance equations for the vibrationally- and the electronically-excited states of a nitrogen and oxygen molecules; nitrogen and oxygen atoms; ozone molecule; and different nitrogen and oxygen ions with different plasmochemical reactions between them. Simulations predicted the main regions of the dc glow discharges including cathode and anode sheath and plasma of negative glow, Faraday dark space and transition region. Gas heating plays an important role in shaping the discharge profiles. The results of experiments and simulations of short (without positive column) atmospheric pressure dc glow discharge in air are presented. We used metal steel electrodes with a gap of 5-100 microns. The experimental voltage-current characteristic's (VAC) have a constant or slightly increasing form at low gap. The most stable microdischarges were burning with a flat cathode and rounded anode, when the length of the discharge is automatically established near the minimum of the Paschen curve by changing their binding on the anode. In this case microdischarge was stable and it had growing VAC. For simulations we used 2D fluid model with kinetic description of electrons. We solved the balance equations for the vibrationally- and the electronically-excited states of a nitrogen and oxygen molecules; nitrogen

Integration issues of a plasma contactor Power Electronics Unit

Science.gov (United States)

Pinero, Luis R.; York, Kenneth W.; Bowers, Glen E.

1995-01-01

A hollow cathode-based plasma contactor is baselined on International Space Station Alpha (ISSA) for spacecraft charge control. The plasma contactor system consists of a hollow cathode assembly (HCA), a power electronics unit (PEU), and an expellant management unit (EMU). The plasma contactor has recently been required to operate in a cyclic mode to conserve xenon expellant and extend system life. Originally, a DC cathode heater converter was baselined for a continuous operation mode because only a few ignitions of the hollow cathode were expected. However, for cyclic operation, a DC heater supply can potentially result in hollow cathode heater component failure due to the DC electrostatic field. This can prevent the heater from attaining the proper cathode tip temperature for reliable ignition of the hollow cathode. To mitigate this problem, an AC cathode heater supply was therefore designed, fabricated, and installed into a modified PEU. The PEU was tested using resistive loads and then integrated with an engineering model hollow cathode to demonstrate stable steady-state operation. Integration issues such as the effect of line and load impedance on the output of the AC cathode heater supply and the characterization of the temperature profile of the heater under AC excitation were investigated.

High Voltage Coil Current Sensor for DC-DC Converters Employing DDCC

Directory of Open Access Journals (Sweden)

M. Drinovsky

2015-12-01

Full Text Available Current sensor is an integral part of every switching converter. It is used for over-current protection, regulation and in case of multiphase converters for balancing. A new high voltage current sensor for coil-based current sensing in DC-DC converters is presented. The sensor employs DDCC with high voltage input stage and gain trimming. The circuit has been simulated and implemented in 0.35 um BCD technology as part of a multiphase DC-DC converter where its function has been verified. The circuit is able to sustain common mode voltage on the input up to 40 V, it occupies 0.387*0.345 mm2 and consumes 3.2 mW typically.

A study of the solid and gaseous products generated by a dc plasma torch under coal and steam injection

International Nuclear Information System (INIS)

Beuthe, T.G.; Chang, J.S.; Irons, G.A.; Lu, W.K.; Berezin, A.A.; Chu, E.Y.

1988-01-01

In this work, the solid and gaseous products generated by a DC plasma torch under simultaneous coal powder and supersaturated steam injection are examined. A range of steam (0.75[g/min]) and coal powder (0-10[g/min]) were injected into the hot argon plasma and the product gases were analyzed by gas chromatographic techniques, an optical multichannel analyzer and infrared CO and CO/sub 2/ analyzers. The solid product generated by the present process was analyzed using neutron activation analysis and scanning electron microscopy. Results indicate that the most common product constituents consisted of simple compounds such as carbon dioxide, carbon monoxide, hydrogen, oxygen and nitrogen. Detailed analysis using infra-red analyzers and gas chromatographic techniques showed that the product gas contained significant amounts of H/sub 2/(--2[%], CO(0.5-4.5[%]) and CO/sub 2/(0.5-1.0[%]) gases, where approximately 80 (%) was still argon gas. Evidence was found of slight amounts of OH, but no significant amount of CH/sub 2/ compounds were detected. The energy yields of the CO/sub 2/ and CO production rates were in the range of 4-10 and 5-25 [g/kWhr] respectively. The produced gas CO:CO/sub 2/ concentration ratio was approximately in the order of 10. Neutron activation analysis shows that the solid product generated in the present process is significantly different from the ash produced by a conventional coal fired furnace. The overall concentrations of trace oxides are significantly lower in the solid product than in conventional ash, tending to support the hypothesis that the solid product is a coke rather than an ash. The conditions in the plasma torch also seem to favour the removal of Ca, S and Si oxides from the coal. Downstream temperature analysis indicates the product gas can be heated from 600 to 1500(K) depending on the torch operating conditions and injectant flowrates

Direct atomic-emission determination of tungsten in molybdenum oxide in dc arc

International Nuclear Information System (INIS)

Zolotareva, N.I.; Grazhulene, S.S.

2007-01-01

A method of direct atomic-emission determination of tungsten impurity in molybdenum trioxide of high purity in dc arc is presented. Chemically active additives of elementary sulfur and gallium oxide are used to optimize W evaporation rate and residence time in the arc plasma. The procedure is easy to use and provides the limit of W determination at a level of 2x10 -4 wt. % [ru

Water plasma generation under atmospheric pressure for HFC destruction

International Nuclear Information System (INIS)

Watanabe, Takayuki; Tsuru, Taira

2008-01-01

The purpose of this paper is to investigate the decomposition process of hydrofluoroethylene (HFC-134a) by water plasmas. The water plasma was generated by DC arc discharge with a cathode of hafnium embedded into a copper rod and a nozzle-type copper anode. The advantage of the water plasma torch is the generation of 100%-water plasma by DC discharge. The distinctive steam generation leads to the portable light-weight plasma generation system that does not require the gas supply unit, as well as the high energy efficiency owing to the nonnecessity of the additional water-cooling. HFC-134a was injected into the water plasma jet to decompose it in the reaction tube. Neutralization vessel was combined to the reaction tube to absorb F 2 and HF generated from the HFC-134a decomposition. The decomposition was performed with changing the feed rate of HFC-134a up to 185 mmol/min. The decomposition efficiency of 99.9% can be obtained up to 0.43 mmol/kJ of the ratio of HFC-134a feed rate to the arc power, hence the maximum feed rate was estimated to be 160 g/h at 1 kW of the arc power

Plasma technology for treatment of waste

Energy Technology Data Exchange (ETDEWEB)

Cohn, D [Massachusetts Inst. of Technology, Cambridge, MA (United States). Plasma Fusion Center

1997-12-31

Meeting goals for waste cleanup will require new technology with improved environmental attractiveness and reduced cost. Plasma technology appears promising because of the high degree of controllability; capability to process waste without the adverse effects of combustion; and a very wide temperature range of operation. At the Plasma Fusion Center at the Massachusetts Institute of Technology, a range of plasma technologies are being investigated. `Hot` thermal plasmas produced by DC arc technology are being examined for treatment of solid waste. In conjunction with this activity, new diagnostics are being developed for monitoring arc furnace operating parameters and gaseous emissions. Electron-beam generated plasma technology is being investigated as a means of producing non-thermal `cold` plasmas for selective processing of dilute concentrations of gaseous waste. (author). 4 figs., 5 refs.

The Plasma Discharge System For Effective Sterilization Of Water And Solid Surfaces

International Nuclear Information System (INIS)

Senturk, K.

2010-01-01

The different areas such as medicine, surgery, food production need efficient sterilization system since they are directly related to human health. In this work a new plasma system is described in order to present its effectiveness in sterilization. This is a different method from conventional methods such as: chemicals and heat addition, UV irradiation etc. The developed plasma system produces cold plasma working under atmospheric pressure. To generate the plasma both AC and DC high voltage power supplies were used. The developed system is cheap and very effective for sterilization. The light emission for both AC and DC coronas for the plasmas were investigated to understand the nature of generated plasma ionization. Different parameters like temperature, voltage, application time were changed during the plasma application and the optimization for killing the micro-organisms were investigated. To understand the biological effect of plasma on the organisms comparisons were done by using the scanning electron microscope and absorption spectrometer. The plasma was applied on the bacteria like Escherichia coli, Bacillus subtilis, Streptococcus mutans , the yeasts such as Candida albicans, and green algae. The efficiency, the non toxic nature, the affordable price make this plasma discharge method a very efficient one for sterilization.

Rf-biasing of highly idealized plasmas

NARCIS (Netherlands)

Westermann, R.H.J.; Blauw, M.A.; Goedheer, W.J.; Sanden, van de M.C.M.; Schmidt, J.; Simek, M.; Pekarek, S.; Prukner, V.

2007-01-01

Remote plasmas, which are subjected to a radio-frequency (RF) biased surface, have been investigated theoretically and experimentally for decades. The relation between the complex power (DC) voltage characteristics, the ion energy distribution and control losses of the ion bombardment are of

On the modelling of linear-assisted DC-DC voltage regulators for photovoltaic solar energy systems

Science.gov (United States)

Martínez-García, Herminio; García-Vílchez, Encarna

2017-11-01

This paper shows the modelling of linear-assisted or hybrid (linear & switching) DC/DC voltage regulators. In this kind of regulators, an auxiliary linear regulator is used, which objective is to cancel the ripple at the output voltage and provide fast responses for load variations. On the other hand, a switching DC/DC converter, connected in parallel with the linear regulator, allows to supply almost the whole output current demanded by the load. The objective of this topology is to take advantage of the suitable regulation characteristics that series linear voltage regulators have, but almost achieving the high efficiency that switching DC/DC converters provide. Linear-assisted DC/DC regulators are feedback systems with potential instability. Therefore, their modelling is mandatory in order to obtain design guidelines and assure stability of the implemented power supply system.

A Feedback Passivation Design for DC Microgrid and Its DC/DC Converters

Directory of Open Access Journals (Sweden)

Feifan Ji

2016-12-01

Full Text Available There are difficulties in analyzing the stability of microgrids since they are located on various network structures. However, considering that the network often consists of passive elements, the passivity theory is applied in this paper to solve the above-mentioned problem. It has been formerly shown that when the network is weakly strictly positive real (WSPR, the DC microgrid is stable if all interfaces between the microgrid and converters are made to be passive, which is called interface passivity. Then, the feedback passivation method is proposed for the controller design of various DC–DC converters to achieve the interface passivity. The interface passivity is different from the passivity of closed-loop systems on which the passivity based control (PBC concentrates. The feedback passivation design is detailed for typical buck converters and boost converters in terms of conditions that the controller parameters should satisfy. The theoretical results are verified by a hardware-in-loop real-time labotray (RTLab simulation of a DC microgrid with four generators.

RFP plasma experiment at INPE

International Nuclear Information System (INIS)

Ueda, M.; Aso, Y.

1988-01-01

Plasma experiments in CECI, a small Reversed Field Pinch (RFP) apparatus, are described. Preliminary measurements in this device shown the production of a plasma with peak current of 1.3kA and discharge duration of nearly 80μs, when a toroidal DC field of 100G was used. A loop voltage of 40V was measured and a maximum electron temperature of 3eV was estimated for these discharges. Experimental points in the F-θ diagram for CECI indicate that its plasma is approaching the RFP configuration when the discharge is optimize. The probe data also show that the plasma column expands outward. Numerical results indicate that leakage fields have to be reduced below 5G to form appropriate magnetic surfaces. (author) [pt

Plasma assisted heat treatment: annealing

International Nuclear Information System (INIS)

Brunatto, S F; Guimaraes, N V

2009-01-01

This work comprises a new dc plasma application in the metallurgical-mechanical field, called plasma assisted heat treatment, and it presents the first results for annealing. Annealing treatments were performed in 90% reduction cold-rolled niobium samples at 900 deg. C and 60 min, in two different heating ways: (a) in a hollow cathode discharge (HCD) configuration and (b) in a plasma oven configuration. The evolution of the samples' recrystallization was determined by means of the microstructure, microhardness and softening rate characterization. The results indicate that plasma species (ions and neutrals) bombardment in HCD plays an important role in the recrystallization process activation and could lead to technological and economical advantages considering the metallic materials' heat treatment application. (fast track communication)

LDA measurements under plasma conditions

International Nuclear Information System (INIS)

Lesinski, J.; Mizera-Lesinska, B.; Fanton, J.C.; Boulos, M.I.

1979-01-01

A study was made of the application of Laser Doppler Anemometry (LDA) for the measurement of the fluid and particle velocities under plasma conditions. The flow configuration, is that of a dc plasma jet called the principal jet, in which an alumina powder of a mean particle diameter of 115 μm and a standard deviation of 11.3 μm was injected using a secondary jet. The plasma jet immerged from a 7.1 mm ID nozzle while that of the secondary jet was 2 nm in diameter. The secondary jet was introduced at the nozzle level of the plasma jet directed 90 0 to its axis. Details of the nozzle and the gas flow system are shown in Figure 2

Elongated dust clouds in a uniform DC positive column of low pressure gas discharge

International Nuclear Information System (INIS)

Usachev, A D; Zobnin, A V; Petrov, O F; Fortov, V E; Thoma, M H; Pustylnik, M Y; Fink, M A; Morfill, G E

2016-01-01

Experimental investigations of the formation of elongated dust clouds and their influence on the plasma glow intensity of the uniform direct current (DC) positive column (PC) have been performed under microgravity conditions. For the axial stabilization of the dust cloud position a polarity switching DC gas discharge with a switching frequency of 250 Hz was used. During the experiment, a spontaneous division of one elongated dust cloud into two smaller steady state dust clouds has been observed. Quantitative data on the dust cloud shape, size and dust number density distribution were obtained. Axial and radial distributions of plasma emission within the 585.2 nm and 703.2 nm neon spectral lines were measured over the whole discharge volume. It has been found that both spectral line intensities at the dust cloud region grew 1.7 times with respect to the undisturbed positive column region; in this the 585.2 nm line intensity increased by 10% compared to the 703.2 nm line intensity. For a semi-quantitative explanation of the observed phenomena the Schottky approach based on the equation of diffusion was used. The model reasonably explains the observed glow enhancement as an increasing of the ionization rate in the discharge with dust cloud, which compensates ion-electron recombination on the dust grain surfaces. In this, the ionization rate increases due to the growing of the DC axial electric field, and the glow grows directly proportional to the electric field. It is shown that the fundamental condition of the radial stability of the dusty plasma cloud is equal to the ionization and recombination rates within the cloud volume that is possible only when the electron density is constant and the radial electric field is absent within the dust cloud. (paper)

Test Results of Selected Commercial DC/DC Converters under Cryogenic Temperatures - A Digest

Science.gov (United States)

Patterson, Richard; Hammoud, Ahmad

2010-01-01

DC/DC converters are widely used in space power systems in the areas of power management and distribution, signal conditioning, and motor control. Design of DC/DC converters to survive cryogenic temperatures will improve the power system performance, simplify design, and reduce development and launch costs. In this work, the performance of nine COTS modular, low-tomedium power DC/DC converters was investigated under cryogenic temperatures. The converters were evaluated in terms of their output regulation, efficiency, and input and output currents. At a given temperature, these properties were obtained at various input voltages and at different load levels. A summary on the performance of the tested converters was given. More comprehensive testing and in-depth analysis of performance under long-term exposure to extreme temperatures are deemed necessary to establish the suitability of these and other devices for use in the harsh environment of space exploration missions.

A Bidirectional Resonant DC-DC Converter Suitable for Wide Voltage Gain Range

DEFF Research Database (Denmark)

Shen, Yanfeng; Wang, Huai; Al-Durra, Ahmed

2018-01-01

This paper proposes a new bidirectional resonant dc-dc converter suitable for wide voltage gain range applications (e.g., energy storage systems). The proposed converter overcomes the narrow voltage gain range of conventional resonant dc-dc converters, and meanwhile achieves high efficiency...... losses. The operation principles and characteristics of the proposed converter are firstly analyzed in this paper. Then the analytical solutions for the voltage gain, soft-switching, and rms currents are derived, which facilitates the parameters design and optimization. Finally, the proposed topology...... and analysis are verified with experimental results obtained from a 1-kW converter prototype....

High-density plasma etching characteristics of indium-gallium-zinc oxide thin films in CF{sub 4}/Ar plasma

Energy Technology Data Exchange (ETDEWEB)

Joo, Young-Hee; Kim, Chang-Il

2015-05-29

We investigated the etching process of indium-gallium-zinc oxide (IGZO) thin films in an inductively coupled plasma system. The dry etching characteristics of the IGZO thin films were studied by varying the CF{sub 4}/Ar gas mixing ratio, RF power, DC-bias voltage, and process pressure. We determined the following optimized process conditions: an RF power of 700 W, a DC-bias voltage of − 150 V, and a process pressure of 2 Pa. A maximum etch rate of 25.63 nm/min for the IGZO thin films was achieved in a plasma with CF{sub 4}/Ar(= 25:75), and the selectivity of IGZO to Al and TiN was found to be 1.3 and 0.7, respectively. We determined the ionic composition of the CF{sub 4}/Ar plasma using optical emission spectroscopy. Analysis of chemical reactions at the IGZO thin film surfaces was performed using X-ray photoelectron spectroscopy. - Highlights: • IGZO thin film was etched by CF{sub 4}/Ar plasma as a function of gas mixing ratio. • IGZO bonds were broken Ar{sup +} sputtering and then reacted with the C-F{sub x} radicals. • The physical sputtering is dominant in etch control compared with chemical etching.

Effect of driving voltages in dual capacitively coupled radio frequency plasma: A study by nonlinear global model

International Nuclear Information System (INIS)

Bora, B.

2015-01-01

On the basis of nonlinear global model, a dual frequency capacitively coupled radio frequency plasma driven by 13.56 MHz and 27.12 MHz has been studied to investigate the influences of driving voltages on the generation of dc self-bias and plasma heating. Fluid equations for the ions inside the plasma sheath have been considered to determine the voltage-charge relations of the plasma sheath. Geometrically symmetric as well as asymmetric cases with finite geometrical asymmetry of 1.2 (ratio of electrodes area) have been considered to make the study more reasonable to experiment. The electrical asymmetry effect (EAE) and finite geometrical asymmetry is found to work differently in controlling the dc self-bias. The amount of EAE has been primarily controlled by the phase angle between the two consecutive harmonics waveforms. The incorporation of the finite geometrical asymmetry in the calculations shift the dc self-bias towards negative polarity direction while increasing the amount of EAE is found to increase the dc self-bias in either direction. For phase angle between the two waveforms ϕ = 0 and ϕ = π/2, the amount of EAE increases significantly with increasing the low frequency voltage, whereas no such increase in the amount of EAE is found with increasing high frequency voltage. In contrast to the geometrically symmetric case, where the variation of the dc self-bias with driving voltages for phase angle ϕ = 0 and π/2 are just opposite in polarity, the variation for the geometrically asymmetric case is different for ϕ = 0 and π/2. In asymmetric case, for ϕ = 0, the dc self-bias increases towards the negative direction with increasing both the low and high frequency voltages, but for the ϕ = π/2, the dc-self bias is increased towards positive direction with increasing low frequency voltage while dc self-bias increases towards negative direction with increasing high frequency voltage

Y-source impedance-network-based isolated boost DC/DC converter

DEFF Research Database (Denmark)

Siwakoti, Yam P.; Town, Graham; Loh, Poh Chiang

2014-01-01

A dc-dc converter with very high voltage gain is proposed in this paper for any medium-power application requiring a high voltage boost with galvanic isolation. The proposed converter topology can be realized using only two switches. With this topology a very high voltage boost can be achieved even...... with a relatively low duty cycle of the switches, and the gain obtainable is presently not matched by any existing impedance network based converter operated at the same duty ratio. The proposed converter has a Y-source impedance network to boost the voltage at the intermediate dc-link side and a push......-pull transformer for square-wave AC inversion and isolation. The voltage-doubler rectifier provides a constant dc voltage at the output stage. A theoretical analysis of the converter is presented, supported by simulation and experimental results. A 250 W down-scaled prototype was implemented in the laboratory...

Multilevel DC link inverter

Science.gov (United States)

Su, Gui-Jia

2003-06-10

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

Stability analysis of a high-step-Up DC grid-connected two-stage boost DC-DC converter

Directory of Open Access Journals (Sweden)

El Aroudi A.

2014-01-01

Full Text Available High conversion ratio switching converters are used whenever there is a need to step-up dc source voltage level to a much higher output dc voltage level such as in photovoltaic systems, telecommunications and in some medical applications. A simple solution for achieving this high conversion ratio is by cascading different stages of dc-dc boost converters. The individual converters in such a cascaded system are usually designed separately applying classical design criteria. However these criteria may not be applicable for the complete cascaded system . This paper first presents a glimpse on the bifurcation behavior that a cascade connection of two boost converters can exhibit. It is shown that the desired periodic orbit can undergo period doubling leading to subharmonic oscillations and chaotic regimes. Then, in order to simplify the analysis the second stage is considered as constant current sink and design-oriented analysis is carried out to obtain stability boundaries in the parameter space by taking into account slope interactions between the state variables in the two-different stages.

Characteristic study of DC electric Arc plasma igniter jet

International Nuclear Information System (INIS)

Lan Yudan; He Liming; Du Hongliang; Wang Feng; Chen Xin

2012-01-01

The spectrometer was adopted to measure the emission spectrum of Ar plasma jet at the igniter exit. Boltzmann curve slope method was applied to calculate the jet electron temperature. Ionization equilibrium equation was used to calculate jet temperature and measure the laws that jet length, jet velocity, electron temperature and jet temperature of igniter exit change with arc current and inlet Ar flow rate. Whether the electron temperature could be used to replace jet temperature in aircraft plasma arc jet was also discussed. The experiment results show that arc current reduces with the rising of inlet Ar flow rate; exit jet length and velocity increase with the rising of arc current, and increase at first and then reduce with the rising of inlet Ar flow rate; exit electron temperature, electron density and jet temperature increase with the rising of arc current and reduce with the rising of inlet Ar flow rate. (authors)

Studi Komparasi Fungsi Keanggotaan Fuzzy sebagai Kontroler Bidirectional DC-DC Converter pada Sistem Penyimpan Energi

Directory of Open Access Journals (Sweden)

Eka Prasetyono

2015-09-01

Full Text Available Bidirectional DC-DC converter is needed in the energy storage system. The converter topology used in this paper was a non-isolated bidirectional DC-DC buck-boost converter. This converter worked in two ways, which the charging mode stored energy into battery when load current was less than nominal main DC current (set point and discharging mode transferred energy from battery to the load when its current exceeded set point value. Both of these modes worked automatically according to the load current. The charging and discharging currents were controlled by fuzzy logic controller which was implemented on microcontroller ARM Cortex-M4F STM32F407VG. This paper compares two types of fuzzy membership function (triangular and sigmoid in controlling bidirectional DC-DC converter. The results showed that fuzzy logic controller with triangle membership function and sigmoid as control bidirectional DC-DC converter had no significant different response, both had an average error for charging and discharging process under 4% with ripple current on the main DC bus around 0.5%. The computing time of program for fuzzy logic controller with triangular membership functions had 19.01% faster than sigmoid, and fuzzy logic computation time on a microcontroller with hardware floating point was 60% faster than software floating point.

Low pressure plasmas and microstructuring technology

CERN Document Server

Franz, Gerhard

2009-01-01

A monograph that presents a perspective of gas discharge physics and its applications to various industries. It presents an overview of the different types to generate plasmas by DC discharges, capacitive and inductive radiofrequency coupling, helicon waves including electron cyclotron resonance, and ion beams.

Development of a 130-mA, 75-kV high voltage column for high-intensity dc proton injectors

International Nuclear Information System (INIS)

Sherman, J.; Arvin, A.; Hansborough, L.; Hodgkins, D.; Meyer, E.; Schneider, J.D.; Stevens, R.R. Jr.; Zaugg, T.

1997-01-01

A reliable high-voltage (HV) column has been developed for dc proton injectors with applications to high-intensity cw linacs. The HV column is coupled with a microwave-driven plasma generator to produce a 75-keV, 110-mA dc proton beam. Typical proton fraction from this source is 85--90%, requiring the HV column and accelerating electrodes to operate with a 130-mA hydrogen-ion beam current. A glow-discharge, which was caused by the ion source axial magnetic field, was initially observed in the HV column. This problem was solved by scaling the electron production processes, the magnetic field, and the HV column pressure into a favorable regime. A subsequent 168 hour reliability run on the 75-keV injector showed that the ion source (plasma generator and HV column) has >98% beam availability

Digitally intensive DC-DC converter for extreme space environments, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — The Space Micro-Arizona State University (ASU) team will develop an all-digitally controlled, wide temperature range point-of-load switch-mode DC-DC regulator core...

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

International Nuclear Information System (INIS)

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

2013-01-01

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

Magnetic field approaches in dc thermal plasma modelling

International Nuclear Information System (INIS)

Freton, P; Gonzalez, J J; Masquere, M; Reichert, Frank

2011-01-01

The self-induced magnetic field has an important role in thermal plasma configurations generated by electric arcs as it generates velocity through Lorentz forces. In the models a good representation of the magnetic field is thus necessary. Several approaches exist to calculate the self-induced magnetic field such as the Maxwell-Ampere formulation, the vector potential approach combined with different kinds of boundary conditions or the Biot and Savart (B and S) formulation. The calculation of the self-induced magnetic field is alone a difficult problem and only few papers of the thermal plasma community speak on this subject. In this study different approaches with different boundary conditions are applied on two geometries to compare the methods and their limitations. The calculation time is also one of the criteria for the choice of the method and a compromise must be found between method precision and computation time. The study shows the importance of the current carrying path representation in the electrode on the deduced magnetic field. The best compromise consists of using the B and S formulation on the walls and/or edges of the calculation domain to determine the boundary conditions and to solve the vector potential in a 2D system. This approach provides results identical to those obtained using the B and S formulation over the entire domain but with a considerable decrease in calculation time.

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

Science.gov (United States)

Lin, Bor-Ren

2018-04-01

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

A Fixed-Frequency Bidirectional Resonant DC-DC Converter Suitable for Wide Voltage Gain Range

DEFF Research Database (Denmark)

Shen, Yanfeng; Wang, Huai; Blaabjerg, Frede

2017-01-01

This paper proposes a new bidirectional resonant dc-dc converter suitable for wide voltage gain range applications (e.g., energy storage systems). The proposed converter overcomes the narrow voltage gain range of conventional resonant DC-DC converters, and meanwhile achieves high efficiency...... and characteristics of the proposed converter are analyzed. Finally, a 1-kW converter prototype is built and the experimental results verify the theoretical analyses....

Pulse-width modulated DC-DC power converters

CERN Document Server

Kazimierczuk, Marian K

2008-01-01

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

Digitally intensive DC-DC converter for extreme space environments, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — The Space Micro –Arizona State University (ASU) team will develop an all-digitally controlled, wide temperature range point-of-load switch-mode DC-DC regulator core...

DC Voltage Droop Control Implementation in the AC/DC Power Flow Algorithm: Combinational Approach

DEFF Research Database (Denmark)

Akhter, F.; Macpherson, D.E.; Harrison, G.P.

2015-01-01

of operational flexibility, as more than one VSC station controls the DC link voltage of the MTDC system. This model enables the study of the effects of DC droop control on the power flows of the combined AC/DC system for steady state studies after VSC station outages or transient conditions without needing...... to use its complete dynamic model. Further, the proposed approach can be extended to include multiple AC and DC grids for combined AC/DC power flow analysis. The algorithm is implemented by modifying the MATPOWER based MATACDC program and the results shows that the algorithm works efficiently....

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

Energy Technology Data Exchange (ETDEWEB)

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

2011-02-15

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

High-Voltage DC-DC Converter Topology for PV Energy Utilization - Investigation and Implementation

DEFF Research Database (Denmark)

Sanjeevikumar, Padmanaban; Blaabjerg, Frede; Wheeler, Patrick

2017-01-01

This paper exploited the utilization of photovoltaic (PV) energy system with high-voltage (HV) output DC-DC converter. Classical boost converters are used for both renewable energy integration and HV applications, but limited by reducing output/efficiency in performance. Moreover, as parasitic...... elements suppress the power transfer ratio, converter needs to maximize the PV energy utilization. This investigation study focused to include additional parasitic elements (voltage-lift technique) to a standard DC-DC buck converter and to overcome all the above drawbacks to maximize the PV power...

Computer Simulation of Phase Shifted Series Resonant DC to DC Converter

Directory of Open Access Journals (Sweden)

P. PARVATHY

2016-01-01

Full Text Available This paper deals with digital simulation of phase shifted series resonant DC to DC converter using Matlab Simulink. The Simulink models for open loop and closed loop systems are developed and they are used for simulation studies. This converter is capable of producing ripple free DC output. Switching losses and switching stresses are reduced by using soft switching. This converter has advantages like high power density and low switching losses. Theoretical predictions are well supported by the simulation results.

A saw-tooth plasma actuator for film cooling efficiency enhancement of a shaped hole

Science.gov (United States)

Li, Guozhan; Yu, Jianyang; Liu, Huaping; Chen, Fu; Song, Yanping

2017-08-01

This paper reports the large eddy simulations of the effects of a saw-tooth plasma actuator and the laidback fan-shaped hole on the film cooling flow characteristics, and the numerical results are compared with a corresponding standard configuration (cylindrical hole without the saw-tooth plasma actuator). For this numerical research, the saw-tooth plasma actuator is installed just downstream of the cooling hole and a phenomenological plasma model is employed to provide the 3D plasma force vectors. The results show that thanks to the downward force and the momentum injection effect of the saw-tooth plasma actuator, the cold jet comes closer to the wall surface and extends further downstream. The saw-tooth plasma actuator also induces a new pair of vortex which weakens the strength of the counter-rotating vortex pair (CRVP) and entrains the coolant towards the wall, and thus the diffusion of the cold jet in the crossflow is suppressed. Furthermore, the laidback fan-shaped hole reduces the vertical jet velocity causing the disappearance of downstream spiral separation node vortices, this compensates for the deficiency of the saw-tooth plasma actuator. Both effects of the laidback fan-shaped hole and the saw-tooth plasma actuator effectively control the development of the CRVP whose size and strength are smaller than those of the anti-counter rotating vortex pair in the far field, thus the centerline and the spanwise-averaged film cooling efficiency are enhanced. The average film cooling efficiency is the biggest in the Fan-Dc = 1 case, which is 80% bigger than that in the Fan-Dc = 0 case and 288% bigger than that in the Cyl-Dc = 0 case.

Power flow analysis for DC voltage droop controlled DC microgrids

DEFF Research Database (Denmark)

Li, Chendan; Chaudhary, Sanjay; Dragicevic, Tomislav

2014-01-01

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

Light weight, high power, high voltage dc/dc converter technologies

Science.gov (United States)

Kraus, Robert; Myers, Ira; Baumann, Eric

1990-01-01

Power-conditioning weight reductions by orders of magnitude will be required to enable the megawatt-power-level space systems envisioned by the Strategic Defense Initiative, the Air Force, and NASA. An interagency program has been initiated to develop an 0.1-kg/kW dc/dc converter technology base for these future space applications. Three contractors are in the first phase of a competitive program to develop a megawatt dc/dc converter. Researchers at NASA Lewis Research Center are investigating innovative converter topology control. Three different converter subsystems based on square wave, resonant, and super-resonant topologies are being designed. The components required for the converter designs cover a wide array of technologies. Two different switches, one semiconductor and the other gas, are under development. Issues related to thermal management and material reliability for inductors, transformers, and capacitors are being investigated in order to maximize power density. A brief description of each of the concepts proposed to meet the goals of this program is presented.

Joule Heating of Plasma in the Toroidal Tokamak-3 Device; Chauffage du Plasma par Effet Joule, dans l'Installation Torique; Dzhoulev nagrev plazmy na toroidal'noj ustanovke Tokamak-3; Calentamiento de un Plasma por Efeto Joule en la Instalacion Toroidal Tokamak

Energy Technology Data Exchange (ETDEWEB)

Arcimovich, L. A.; Afrosimov, V. V.; Gladkovskij, I. P.; Mirnov, S. V.; Petrov, M. P.; Strelkov, V. S. [Institut Atomnoj Ehnergii, Im. I.V. Kurchatova, Moskva, SSSR (Russian Federation)

1966-04-15

la colonne, qui peut s'expliquer par la presence, a l'interieur de la colonne, de flux de derive d'ions ayant de grandes vitesses transversales. (author) [Spanish] En la instalacion Tokamak-3 el plasma de hidrogeno se obtiene y calienta con una corriente electrica anular de 40 a 60 kA. El tiempo de paso de la corriente es de 20 a 30 ms. Muchos de los experimentos se efectuaron con un campo magnetico longitudinal estabilizado de 25 kOe. La componente transversal del campo magnetico disperso se compenso con ayuda de corrientes procedentes de circuitos correctores especiales. Durante la descarga no tuvo lugar ningun desplazamiento perceptible del centro de la columna con respecto al plano ecuatorial del toro y se observo una deriva de la columna de plasma 'hacia el exterior' (aumento del radio mayor del circuito). Este movimiento puede ser provocado por un cambio del radio de la columna de corriente, por el calentamiento del plasma o por el amortiguamiento de las corrientes de Foucault en el recipiente conductor. En estas condiciones, se consiguio obtener en la instalacion Tokamak-3 una columna de plasma macroscopicamente estable; sin embargo, la temperatura del plasma fue inferior a la que era de esperar en ausencia de perdidas anomalas de energia. Los procesos que tienen lugar durante la interaccion de la columna plasmatica con el diafragma originan grandes perdidas de energfa. Esta interaccion pudo atenuarse dando al diafragma una forma especial y utilizando la propiedad de la columna de desplazarse hacia el exterior en el transcurso del proceso. El problema investigado consistia en determinar varios parametros del plasma en estas condiciones, en particular las temperaturas electronica y ionica. Para determinar la temperatura electronica basandose en los cambios de la resistencia del plasma, es preciso conocer ademas de las caracteristicas electricas de la columna, la ley que rige el cambio del radio de esta ultima en funcion del tiempo. La solucion, utilizando un

Digital peak current mode control with adaptive slope compensation for DC-DC converters

DEFF Research Database (Denmark)

Andersen, Karsten Holm; Nymand, Morten

2017-01-01

performance and stability of current mode control. The presented method adapt to DC-DC converter operating conditions by estimating the rising and falling inductor current slopes, to apply a current slope compensation value to obtain a constant quality factor. The experimental results verifies the theoretical......This paper presents an adaptive slope compensation method for peak current mode control of digital controlled DC-DC converters, which controls the quality factor of the complex conjugated poles at half the switching frequency. Using quality factor control enables optimization of the dynamic...

DC-Link Compensation Method for Slim DC Link Drives Fed by Soft Grid

DEFF Research Database (Denmark)

Mathe, Laszlo; Rosendahl Andersen, Henrik; Lazar, Radu

2010-01-01

Slim DC-link PWM (AC) drives for lowperformance applications are emerging on the market. Such drives equipped with a small DC-link capacitance exhibit instability tendencies, if installed on a soft line, giving a degraded performance. The total harmonic distortion (THD) and the partially weighted...... harmonic distortion (PWHD) of the line current are degraded, if resonance between the line impedance and the DC-link capacitance occurs. Likewise, the motor performance is affected negatively giving extra torque ripple, vibration and acoustic-noise emission. This paper proposes a novel DC-link compensation...

High-power three-port three-phase bidirectional DC-DC converter

NARCIS (Netherlands)

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

2007-01-01

This paper proposes a three-port three-phase bidirectional dc-dc converter suitable for high-power applications. The converter combines a slow primary source and a fast storage to power a common load (e.g., an inverter). Since this type of system is gaining popularity in sustainable energy

Precharge strategies for isolated modular DC-DC converters under two different start-up conditions

DEFF Research Database (Denmark)

Zhang, Yi; Wang, Huai; Li, Binbin

2017-01-01

The isolated modular DC-DC converter (IMDCC) is a new topology designed to connect high-voltage direct current (HVDC) lines with different voltage levels, which ties two DC grids by using two modular multilevel converters (MMCs) via a medium-frequency transformer. Due to the large value of capaci......The isolated modular DC-DC converter (IMDCC) is a new topology designed to connect high-voltage direct current (HVDC) lines with different voltage levels, which ties two DC grids by using two modular multilevel converters (MMCs) via a medium-frequency transformer. Due to the large value...... of capacitance in the IMDCC, proper precharge strategies before the start-up are significant for the safety and reliability of the whole system. This paper presents two closed-loop precharge control strategies to fully charge the sub-module (SM) capacitors of the IMDCC, considering two different start...

Modeling and analysis of fractional order DC-DC converter.

Science.gov (United States)

Radwan, Ahmed G; Emira, Ahmed A; AbdelAty, Amr M; Azar, Ahmad Taher

2017-07-11

Due to the non-idealities of commercial inductors, the demand for a better model that accurately describe their dynamic response is elevated. So, the fractional order models of Buck, Boost and Buck-Boost DC-DC converters are presented in this paper. The detailed analysis is made for the two most common modes of converter operation: Continuous Conduction Mode (CCM) and Discontinuous Conduction Mode (DCM). Closed form time domain expressions are derived for inductor currents, voltage gain, average current, conduction time and power efficiency where the effect of the fractional order inductor is found to be strongly present. For example, the peak inductor current at steady state increases with decreasing the inductor order. Advanced Design Systems (ADS) circuit simulations are used to verify the derived formulas, where the fractional order inductor is simulated using Valsa Constant Phase Element (CPE) approximation and Generalized Impedance Converter (GIC). Different simulation results are introduced with good matching to the theoretical formulas for the three DC-DC converter topologies under different fractional orders. A comprehensive comparison with the recently published literature is presented to show the advantages and disadvantages of each approach. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Measurement of Stark width of some Ar I transitions and the investigation of local thermodynamic equilibrium (LTE) in an atmospheric d.c. argon plasma jet

International Nuclear Information System (INIS)

Bakshi, V.

1988-01-01

The Stark widths of seven Ar I transitions are reported. Axial line shape data from an atmospheric d.c. argon plasma jet were Abel-inverted to obtain radial line shapes. The electron-density was determined by Stark width measurements of the hydrogen H β transition. In the electron-density region of ≤6 x 10 22 m -3 the experimental Ar I Stark widths are fitted to a linear dependence on the electron-density. Values of Stark width extrapolated to other electron densities are compared to measurements reported in the literature on the 4s-4p array. Experimental values are up to 45% smaller than those predicted by Griem's theory of Stark broadening. Conditions for local thermodynamic equilibrium (LTE) to exist in an atmospheric argon plasma jet were studied. The experiment measures the emission coefficient of seven Ar I transitions and the line shape of the hydrogen H beta transition. After transforming the side-on data into radial space the excited neutral argon atom-density and the electron-density are determined. It is found LTE does not exist below an electron-density of 6 x 10 33 m -3 in the experimental conditions

Magnetically coupled high-gain Y-source isolated DC/DC converter

DEFF Research Database (Denmark)

Siwakoti, Yam P.; Loh, Poh Chiang; Blaabjerg, Frede

2014-01-01

A new form of magnetically coupled DC/DC converter is proposed for medium power applications (250 W to 2 kW), requiring a high-voltage gain, short inductive charging time and galvanic isolation. The proposed converter can be realised using a unique Y-source impedance network and a two-switch push...

Resolidificación con láser de barreras térmicas de circona depositadas por proyección térmica plasma (APS

Directory of Open Access Journals (Sweden)

Diez, J. C.

2004-12-01

Full Text Available Coatings of partially stabilised zirconia are currently used as thermal barrier coatings in gas turbines and diesel engines. Zirconia coatings are usually processed via plasma spraying a well-established and relatively cheap technique. Thermal barrier coatings consist of 0.5 to 1 mm of porous ceramic bonded to the metallic substrate by a bond-coat. High porosity in the ceramic coating assure a good thermal behaviour but increases the chances for corrosion or chemical attack of the bondcoat and coating detach by delamination processes. The as sprayed surface is rough and sensitive to erosion. In the present work we obtained the processing conditions for laser remelting of Y-PSZ coatings deposited by atmospheric plasma spraying technique on Ni- alloys. A simple model accounts for the onset melting energy and its dependence with the processing speed. The remelted film is dense and with smooth surface and well bonded to the underlying porous coat.

Los recubrimientos de circona parcialmente estabilizada con itria se usan habitualmente como barreras térmicas en turbinas y motores. Estos recubrimientos se suelen realizar mediante proyección térmica plasma (APS, una técnica relativamente económica y bien conocida en el sector industrial. Las barreras consisten de una capa de 0.5 a 1 mm de cerámica muy porosa unida a la aleación metálica mediante una capa de enlace. La elevada porosidad permite incrementar la resistencia al choque térmico pero provoca que el oxigeno u otros gases perniciosos para el substrato lleguen con relativa facilidad, produciéndose ataques que pueden acelerar el proceso de delaminación. Asimismo la superficie es rugosa y por tanto expuesta a la erosión por partículas. En este trabajo se presentan las condiciones óptimas que permiten la resolidificación mediante láser de la superficie de las capas de Y-PSZ (circona parcialmente estabilizada con itria depositadas por proyección térmica de plasma en aleaciones

Modelling of plasma-antenna coupling and non-linear radio frequency wave-plasma-wall interactions in the magnetized plasma device under ion cyclotron range of frequencies

International Nuclear Information System (INIS)

Lu, LingFeng

2016-01-01

Ion Cyclotron Resonant Heating (ICRH) by waves in 30-80 MHz range is currently used in magnetic fusion plasmas. Excited by phased arrays of current straps at the plasma periphery, these waves exist under two polarizations. The Fast Wave tunnels through the tenuous plasma edge and propagates to its center where it is absorbed. The parasitically emitted Slow Wave only exists close to the launchers. How much power can be coupled to the center with 1 A current on the straps? How do the emitted radiofrequency (RF) near and far fields interact parasitically with the edge plasma via RF sheath rectification at plasma-wall interfaces? To address these two issues simultaneously, in realistic geometry over the size of ICRH antennas, this thesis upgraded and tested the Self-consistent Sheaths and Waves for ICH (SSWICH) code. SSWICH couples self-consistently RF wave propagation and Direct Current (DC) plasma biasing via non-linear RF and DC sheath boundary conditions (SBCs) at plasma/wall interfaces. Its upgrade is full wave and was implemented in two dimensions (toroidal/radial). New SBCs coupling the two polarizations were derived and implemented along shaped walls tilted with respect to the confinement magnetic field. Using this new tool in the absence of SBCs, we studied the impact of a density decaying continuously inside the antenna box and across the Lower Hybrid (LH) resonance. Up to the memory limits of our workstation, the RF fields below the LH resonance changed with the grid size. However the coupled power spectrum hardly evolved and was only weakly affected by the density inside the box. In presence of SBCs, SSWICH-FW simulations have identified the role of the fast wave on RF sheath excitation and reproduced some key experimental observations. SSWICH-FW was finally adapted to conduct the first electromagnetic and RF-sheath 2D simulations of the cylindrical magnetized plasma device ALINE. (author) [fr

A high voltage ratio and low ripple interleaved DC-DC converter for fuel cell applications.

Science.gov (United States)

Chang, Long-Yi; Chao, Kuei-Hsiang; Chang, Tsang-Chih

2012-01-01

This paper proposes a high voltage ratio and low ripple interleaved boost DC-DC converter, which can be used to reduce the output voltage ripple. This converter transfers the low DC voltage of fuel cell to high DC voltage in DC link. The structure of the converter is parallel with two voltage-doubler boost converters by interleaving their output voltages to reduce the voltage ripple ratio. Besides, it can lower the current stress for the switches and inductors in the system. First, the PSIM software was used to establish a proton exchange membrane fuel cell and a converter circuit model. The simulated and measured results of the fuel cell output characteristic curve are made to verify the correctness of the established simulation model. In addition, some experimental results are made to validate the effectiveness in improving output voltage ripple of the proposed high voltage ratio interleaved boost DC-DC converters.

DC Rocks! Using Place-Based Learning to Introduce Washington DC's K-12 Students to the Geosciences

Science.gov (United States)

Mayberry, G. C.; Mattietti, G. K.

2017-12-01

The Washington DC area has interesting geology and a multitude of agencies that deal with the geosciences, yet K-12 public school students in DC, most of whom are minorities, have limited exposure to the geosciences. Geoscience agencies in the DC area have a unique opportunity to address this by introducing the geosciences to local students who otherwise may not have such an opportunity, by highlighting the geology in the students' "backyard," and by leveraging partnerships among DC-based geoscience-related agencies. The USGS and George Mason University are developing a project called DC Rocks, which will give DC's students an exciting introduction into the world of geoscience with place-based learning opportunities that will make geoscience relevant to their lives and their futures. Both the need in DC and the potential for lasting impact are great; the geosciences have the lowest racial diversity of all the science, technology, engineering, and math (STEM) fields, 89% of students in DC public schools are minorities, and there is no dedicated geoscience curriculum in DC. DC Rocks aims to give these students early exposure to the earth sciences, and encourage them to consider careers in the profession. DC Rocks will work with partner agencies to apply several methods that are recommended by researchers to increase the participation of minority students in the geosciences, including providing profoundly positive experiences that spark interest in the geosciences (Levine et al., 2007); increasing students' sense of belonging in the geosciences (Huntoon, et al, 2016); and place-based teaching practices that emphasize the study of local sites (Semken, 2005), such as DC's Rock Creek Park. DC Rocks will apply these methods by coordinating local geoscientists and resources to provide real-world examples of the geosciences' impact on students' lives. Through the DC Rocks website, educators will be able to request geoscience-related resources such as class presentations by

Radiated electromagnetic emissions of DC-DC converters

International Nuclear Information System (INIS)

Feld, L; Jussen, R; Karpinski, W; Klein, K; Sammet, J; Wlochal, M

2010-01-01

For the CMS tracker at SLHC a new powering scheme is considered to be mandatory to allow the detector to provide at least the same performance as today at the LHC. The baseline solution of CMS foresees the use of DC-DC converters to provide larger currents with smaller losses. An important component of most converters are inductors which, however, tend to radiate the switching noise generated by the converter. The emissions of different inductors have been measured and simulated, the coil design has been optimized and noise susceptibility measurements, with present CMS hardware, have been performed. This article summarizes the results.

Modeling, Analysis and Control of Different DC-DC Converter Topologies for Photo Voltaic Emulator

Directory of Open Access Journals (Sweden)

Mohammad Tauquir Iqbal

2016-05-01

Full Text Available This paper presents the modeling, analysis and control of different DC-DC converter topologies to emulate the photovoltaic (PV system. A PV emulator is basically a DC-DC converter having same electrical characteristics that of solar PV panel.  The emulator helps to achieve real characteristics of PV system in a better way in an environment where using actual PV systems can produce inconsistent results due to variation in weather conditions. The paper describes different types of DC-DC converters like buck, Resonant and Quasi Resonant Converter. The complete system is modelled in MATLAB® Simulink SimPowerSystem software package. The Simulation results obtained from the MATLAB® Simulink SimPowerSystem software package for different topologies under steady and dynamic conditions are analyzed and presented. An evaluation table is also presented at the end of the paper, presenting the effectiveness of each topology.

Studies on fundamental technologies for producing tokamak-plasma

International Nuclear Information System (INIS)

Matsuzaki, Yoshimi

1987-10-01

The report describes studies on fundamental technologies to produce tokamak-plasma of the JFT-2 and JFT-2M tokamaks. (1) In order to measure the particle number of residual gases, calibration methods of vacuum gauges have been developed. (2) Devices for a Taylor-type discharge cleaning (TDC), a glow discharge cleaning (GDC) and ECR discharge cleaning (ECR-DC) have been made and the cleaning effects have been investigated. In TDC the most effective plasma for cleaning is obtained in the plasma with 5 eV of electron temperature. GDC is effective in removing carbon impurities, but is less effective for removing oxygen impurities. ECR-DC has nearly the similar effect as TDC. The cleaning effect of these three types were studied by comparing the properties of resulting tokamak plasmas in the JFT-2M tokamak. (3) Experimental studies of pre-ionization showed as following results; A simple pre-ionization equipment as a hot-electron-gun and a J x B gun was effective in reducing breakdown voltage. An ordinary mode wave of the electron cyclotron frequency was very effective for pre-ionization. The RF power whose density is 3.6 x 10 -2 W/cm 3 produced plasma of an electron density of 5 x 10 11 cm -3 . In this case, it is possible to start up with negligible consumption of the magnetic flux caused by the plasma resistance. (4) Concerning to studies on plasma control, the following results were obtained; In order to obtain constant plasma current, a pulse forming network was constructed and sufficient constant plasma current was achieved. In applying an iso-flux method for measuring the plasma position, it is no problem practically to use only one loop-coil and one magnetic probe. (author)

Homopolar dc motor and trapped flux brushless dc motor using high temperature superconductor materials

Science.gov (United States)

Crapo, Alan D.; Lloyd, Jerry D.

1991-03-01

Two motors have been designed and built for use with high-temperature superconductor (HTSC) materials. They are a homopolar dc motor that uses HTSC field windings and a brushless dc motor that uses bulk HTSC materials to trap flux in steel rotor poles. The HTSC field windings of the homopolar dc motor are designed to operate at 1000 A/sq cm in a 0.010-T field. In order to maximize torque in the homopolar dc motor, an iron magnetic circuit with small air gaps gives maximum flux for minimum Ampere turns in the field. A copper field winding version of the homopolar dc motor has been tested while waiting for 575 A turn HTSC coils. The trapped flux brushless dc motor has been built and is ready to test melt textured bulk HTSC rings that are currently being prepared. The stator of the trapped flux motor will impress a magnetic field in the steel rotor poles with warm HTSC bulk rings. The rings are then cooled to 77 K to trap the flux in the rotor. The motor can then operate as a brushless dc motor.

Rotating dust ring in an RF discharge coupled with a dc-magnetron sputter source. Experiment and simulation

International Nuclear Information System (INIS)

Matyash, K; Froehlich, M; Kersten, H; Thieme, G; Schneider, R; Hannemann, M; Hippler, R

2004-01-01

During an experiment involving coating of dust grains trapped in an RF discharge using a sputtering dc-magnetron source, a rotating dust ring was observed and investigated. After the magnetron was switched on, the dust cloud levitating above the RF electrode formed a ring rotating as a rigid body. Langmuir probe diagnostics were used for the measurement of plasma density and potential. It was discovered that the coupling of the dc-magnetron source to the RF discharge causes steep radial gradients in electron density and plasma potential. The rotation of the dust ring is attributed to the azimuthal component of the ion drag force, which appears due to the azimuthal drift of the ions caused by crossed radial electric and axial magnetic fields. In order to get more insight into the mechanism of dust ring rotation, a Particle-in-Cell simulation of a rotating dust cloud was performed. The results of the experiment and simulation are presented and discussed

Rotating dust ring in an RF discharge coupled with a dc-magnetron sputter source. Experiment and simulation

Energy Technology Data Exchange (ETDEWEB)

Matyash, K [Institut fuer Niedertemperaturplasmaphysik Greifswald, Fr.-L.-Jahn-Strasse 19, 17489 Greifswald (Germany); Froehlich, M [Institut fuer Physik, Ernst-Moritz-Arndt-Universitaet Greifswald, Domstrasse 10a, 17487 Greifswald (Germany); Kersten, H [Institut fuer Niedertemperaturplasmaphysik Greifswald, Fr.-L.-Jahn-Strasse 19, 17489 Greifswald (Germany); Thieme, G [Institut fuer Physik, Ernst-Moritz-Arndt-Universitaet Greifswald, Domstrasse 10a, 17487 Greifswald (Germany); Schneider, R [Max-Planck-Institut fuer Plasmaphysik, Teilinstitut Greifswald, Wendelsteinstrasse 1, 17489 Greifswald (Germany); Hannemann, M [Institut fuer Niedertemperaturplasmaphysik Greifswald, Fr.-L.-Jahn-Strasse 19, 17489 Greifswald (Germany); Hippler, R [Institut fuer Physik, Ernst-Moritz-Arndt-Universitaet Greifswald, Domstrasse 10a, 17487 Greifswald (Germany)

2004-10-07

During an experiment involving coating of dust grains trapped in an RF discharge using a sputtering dc-magnetron source, a rotating dust ring was observed and investigated. After the magnetron was switched on, the dust cloud levitating above the RF electrode formed a ring rotating as a rigid body. Langmuir probe diagnostics were used for the measurement of plasma density and potential. It was discovered that the coupling of the dc-magnetron source to the RF discharge causes steep radial gradients in electron density and plasma potential. The rotation of the dust ring is attributed to the azimuthal component of the ion drag force, which appears due to the azimuthal drift of the ions caused by crossed radial electric and axial magnetic fields. In order to get more insight into the mechanism of dust ring rotation, a Particle-in-Cell simulation of a rotating dust cloud was performed. The results of the experiment and simulation are presented and discussed.

Characterization of a Low Intensity Plasma Jet

International Nuclear Information System (INIS)

Urruchi, W. I.; Maciel, H.S.; Petraconi, G.; Otani, C.

1999-01-01

A source of streaming plasma having charged particles energies in the range of tens of electron volts has been built and characterized. The source is based on a dc glow discharge in a cylindrical tube which is connected to a vacuum chamber through a small orifice. A streaming plasma of conical shape emerging from the orifice is formed when the discharge is run between the cathode located inside the tube and the anode located in the vacuum chamber. The strong constriction of the discharge leads to the formation of a plasma sac, in the orifice region, between the positive column and the plasma beam. Properties of these plasmas were investigated using a movable Langmuir probe and an electrostatic energy analyzer. A mechanism based on the formation of double-layers (DL) between the ''plasma sac'' and the adjacent plasmas is proposed to explain the acceleration of the plasma jet charged particles. (author)

Differential Mode EMI Filter Design for Isolated DC-DC Boost Converter

DEFF Research Database (Denmark)

Makda, Ishtiyaq Ahmed; Nymand, Morten

2014-01-01

A Differential Mode EMI filter for a low input voltage high-current isolated dc-dc boost converter is designed and presented in this paper. The primary side Differential Mode noise voltage is low due to the high transformer turn ratio, however, the input current is very high and since the EMI limit...... also does not change for such converters, it requires greatly optimized design approach for the filter including the correct sizing of the filter components. A complete analytical filter design process is carried out such a way that the Differential Mode noise voltage source in the converter...... is identified first. The DM noise model is then established and based on the harmonic analysis of the noise source voltage waveform, the complete Differential Mode EMI filter, including the filter resonance damping branch, is designed for a 3kW isolated dc-dc boost converter. The noise model and its theoretical...