Space-time-dependent development of the plasma in a pulsed hollow-cathode discharge

International Nuclear Information System (INIS)

Schaefer, G.; Wages, M.

1988-01-01

This paper presents streak camera investigations on the space-time-dependent development of pulsed hollow-cathode discharges (HCD's) starting from low-current preionization discharges. The discharges started closer to the end of the cathode, then moved further into the cathode, and then spread over a longer range along the axis of the cathode. The depth range of the intense pulsed hollow-cathode plasma was found to be two to eight times the cathode diameter

Comparison of gap frame designs and materials for precision cathode strip chambers

International Nuclear Information System (INIS)

Horvath, J.A.; Pratuch, S.M.; Belser, F.C.

1993-01-01

Precision cathode strip chamber perimeter designs that incorporate either continuous or discrete-post gap frames are analyzed. The effects of ten design and material combinations on gravity sag, mass, stress, and deflected shape are evaluated. Procedures are recommended for minimizing mass in the chamber perimeter region while retaining structural integrity and electrical design latitude

Wire- and cathode pulses in a counter of square cross section with a thin wire as central conductor operating in limited streamer mode

Science.gov (United States)

Carli, Ch.; Erd, Ch.; Leder, G.; Pernicka, M.; Regler, M.; Schnizer, B.

1989-11-01

Streamer tubes are becoming increasingly important in high-energy physics experiments. They are used as drift tubes for the localisation of charged-particle tracks, and also as sampling devices in sandwich calorimeters with cathode readout only. The streamer pulses carry charges which are several orders of magnitude larger than pulses from proportional chambers; this provides a good signal-to-noise ratio and makes them appropriate for a wide field of applications in highly compact detectors. The signals induced on the cathodes are also important for measuring — in addition to the anode wire - a second coordinate, and for resolving ambiguities in track recognition. When connecting the signals from two opposite cathodes to the two inputs of a differential amplifier, a left/right bit could be added after suitable buffering via the same signal line as used for time digitalisation. Another essential feature is the association of time information from the anode wire and the cathode. For the streamer tube used in this experiment the pulses induced on the cathode on either side of the particle, and on the anode, are measured by a fast analog-to-digital converter. A simple two-dimensional model ρ( r, θ) at t = 0, without any time-dependent effects other than a constant electron drift velocity of 50 μm/ns, is used to compare the charge distribution in a streamer with the measurements of the pulse lengths at the two opposite cathode strips. First the field generated by a static voltage is calculated. Then the effect of a "space charge" is evaluated. The Green's function of the square domain is a prerequisite for determining the field and the surface charge distribution on the electrodes. It is obtained from that of a concentric circular counter by a conformal mapping. Representations of Green's functions are calculated by series expansions.

Multi-pulsed intense electron beam emission from velvet, carbon fibers, carbon nano-tubes and dispenser cathodes

International Nuclear Information System (INIS)

Xia Liansheng; Yang Anmin; Chen Yi; Zhang Huang; Liu Xingguang; Li Jin; Jiang Xiaoguo; Zhang Kaizhi; Shi Jinshui; Deng Jianjun; Zhang Linwen

2010-01-01

The experimental results of studies of four kinds of cathode emitting intense electron beams are demonstrated under multi-pulsed mode based on an experimental setup including two multi-pulse high voltage sources. The tested cathodes include velvet, carbon fibers, carbon nano-tubes (CNTs) and dispenser cathodes. The results indicate that all four are able to emit multi-pulsed beams. For velvet, carbon fiber and CNTs, the electron induced cathode plasma emission may be the main process and this means that there are differences in beam parameters from pulse to pulse. For dispenser cathodes tested in the experiment, although there is a little difference from pulse to pulse for some reason, thermal-electric field emission may be the main process. (authors)

Determination of mobile form contents of Zn, Cd, Pb and Cu in soil extracts by combined stripping voltammetry

International Nuclear Information System (INIS)

Nedeltcheva, T.; Atanassova, M.; Dimitrov, J.; Stanislavova, L.

2005-01-01

The amount of mobile forms of Zn, Pb, Cd and Cu in extracts obtained by treating soil samples with ammonium nitrate were determined by an appropriate combination of anodic and cathodic stripping voltammetry with hanging mercury drop electrode. Every analysis required three mercury drops: on the first one, zinc was determined; on the second, cadmium and lead; on the third, copper was determined. Zinc, lead and cadmium were determined by conventional differential-pulse anodic stripping voltammetry. For copper determination, adsorptive differential-pulse cathodic stripping voltammetry with amalgamation using chloride ions as a complexing agent was applied. The standard deviation of the results was from 1 to 10% depending on the metal content in the sample. Voltammetric results were in good agreement with the AAS analysis. No microwave digestion of soil extracts was necessary

Determination of mobile form contents of Zn, Cd, Pb and Cu in soil extracts by combined stripping voltammetry

Energy Technology Data Exchange (ETDEWEB)

Nedeltcheva, T. [Department of Analytical Chemistry, University of Chemical Technology and Metallurgy, 8 Kl. Ohridsi Blvd., 1756 Sofia (Bulgaria)]. E-mail: nedel@uctm.edu; Atanassova, M. [Department of Analytical Chemistry, University of Chemical Technology and Metallurgy, 8 Kl. Ohridsi Blvd., 1756 Sofia (Bulgaria); Dimitrov, J. [N. Pushkarov Institute of Soil Science and Agroecology, 7 Shosse Bankya St., 1080 Sofia (Bulgaria); Stanislavova, L. [N. Pushkarov Institute of Soil Science and Agroecology, 7 Shosse Bankya St., 1080 Sofia (Bulgaria)

2005-01-10

The amount of mobile forms of Zn, Pb, Cd and Cu in extracts obtained by treating soil samples with ammonium nitrate were determined by an appropriate combination of anodic and cathodic stripping voltammetry with hanging mercury drop electrode. Every analysis required three mercury drops: on the first one, zinc was determined; on the second, cadmium and lead; on the third, copper was determined. Zinc, lead and cadmium were determined by conventional differential-pulse anodic stripping voltammetry. For copper determination, adsorptive differential-pulse cathodic stripping voltammetry with amalgamation using chloride ions as a complexing agent was applied. The standard deviation of the results was from 1 to 10% depending on the metal content in the sample. Voltammetric results were in good agreement with the AAS analysis. No microwave digestion of soil extracts was necessary.

Spatio-temporal characteristics of self-pulse in hollow cathode discharge

International Nuclear Information System (INIS)

Jing, Ha; He, Shoujie

2015-01-01

The characteristics of self-pulse in hollow cathode discharge at low pressure have been investigated. The voltage-current (V-I) curves, the influence of ballast resistor on the self-pulses, and the evolution of current and voltage are measured. Both the axial and radial spatio-temporal discharge images of self-pulse are recorded. The results show that there exists the hysteresis effect in the present hollow cathode discharge. The high value of ballast resistors is favourable for the observation of self-pulses. The process of the self-pulse can be divided into three stages from the temporal discharge images, i.e., the pre-discharge, the transition from mainly axial electric field to mainly radial electric field, and the decaying process. The self-pulse is suggested to originate from the mode transition of the discharge in essence

Explosive Processes on Cathode while Forming Nanosecond Pulsed Discharge of High Pressure

Directory of Open Access Journals (Sweden)

A. M. Hashimov

2012-01-01

Full Text Available The paper is devoted to research of cathode surfaces with different curvature radius (r = 1–8 mm while forming nanosecond pulsed discharge in dense air. Influence of field and air pressure heterogeneity rate in gas gap on size of micro-craters being formed on working cathode surface after pulsed effect has been shown in the paper. The paper reveals a maximum expansion of separate micro-crater size on cathode surface with small curvature radius.

Performance of the CMS Cathode Strip Chambers with Cosmic Rays

CERN Document Server

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Gomez Ceballos, G; Hahn, K A; Harris, P; Jaditz, S; Kim, Y; Klute, M; Lee, Y J; Li, W; Loizides, C; Ma, T; Miller, M; Nahn, S; Paus, C; Roland, C; Roland, G; Rudolph, M; Stephans, G; Sumorok, K; Sung, K; Vaurynovich, S; Wenger, E A; Wyslouch, B; Xie, S; Yilmaz, Y; Yoon, A S; Bailleux, D; Cooper, S I; Cushman, P; Dahmes, B; De Benedetti, A; Dolgopolov, A; Dudero, P R; Egeland, R; Franzoni, G; Haupt, J; Inyakin, A; Klapoetke, K; Kubota, Y; Mans, J; Mirman, N; Petyt, D; Rekovic, V; Rusack, R; Schroeder, M; Singovsky, A; Zhang, J; Cremaldi, L M; Godang, R; Kroeger, R; Perera, L; Rahmat, R; Sanders, D A; Sonnek, P; Summers, D; Bloom, K; Bockelman, B; Bose, S; Butt, J; Claes, D R; Dominguez, A; Eads, M; Keller, J; Kelly, T; Kravchenko, I; Lazo-Flores, J; Lundstedt, C; Malbouisson, H; Malik, S; Snow, G R; Baur, U; Iashvili, I; Kharchilava, A; Kumar, A; Smith, K; Strang, M; Alverson, G; Barberis, E; Boeriu, O; Eulisse, G; Govi, G; McCauley, T; Musienko, Y; Muzaffar, S; Osborne, I; Paul, T; Reucroft, S; Swain, J; Taylor, L; Tuura, L; Anastassov, A; Gobbi, B; Kubik, A; Ofierzynski, R A; Pozdnyakov, A; Schmitt, M; Stoynev, S; Velasco, M; Won, S; Antonelli, L; Berry, D; Hildreth, M; Jessop, C; Karmgard, D J; Kolberg, T; Lannon, K; Lynch, S; Marinelli, N; Morse, D M; Ruchti, R; Slaunwhite, J; Warchol, J; Wayne, M; Bylsma, B; Durkin, L S; Gilmore, J; Gu, J; Killewald, P; Ling, T Y; Williams, G; Adam, N; Berry, E; Elmer, P; Garmash, A; Gerbaudo, D; Halyo, V; Hunt, A; Jones, J; Laird, E; Marlow, D; Medvedeva, T; Mooney, M; Olsen, J; Piroué, P; Stickland, D; Tully, C; Werner, J S; Wildish, T; Xie, Z; Zuranski, A; Acosta, J G; Bonnett Del Alamo, M; Huang, X T; Lopez, A; Mendez, H; Oliveros, S; Ramirez Vargas, J E; Santacruz, N; Zatzerklyany, A; Alagoz, E; Antillon, E; Barnes, V E; Bolla, G; Bortoletto, D; Everett, A; Garfinkel, A F; Gecse, Z; Gutay, L; Ippolito, N; Jones, M; Koybasi, O; Laasanen, A T; Leonardo, N; Liu, C; Maroussov, V; Merkel, P; Miller, D H; Neumeister, N; Sedov, A; Shipsey, I; Yoo, H D; Zheng, Y; Jindal, P; Parashar, N; Cuplov, V; Ecklund, K M; Geurts, F J M; Liu, J H; Maronde, D; Matveev, M; Padley, B P; Redjimi, R; Roberts, J; Sabbatini, L; Tumanov, A; Betchart, B; Bodek, A; Budd, H; Chung, Y S; de Barbaro, P; Demina, R; Flacher, H; Gotra, Y; Harel, A; Korjenevski, S; Miner, D C; Orbaker, D; Petrillo, G; Vishnevskiy, D; Zielinski, M; Bhatti, A; Demortier, L; Goulianos, K; Hatakeyama, K; Lungu, G; Mesropian, C; Yan, M; Atramentov, O; Bartz, E; Gershtein, Y; Halkiadakis, E; Hits, D; Lath, A; Rose, K; Schnetzer, S; Somalwar, S; Stone, R; Thomas, S; Watts, T L; Cerizza, G; Hollingsworth, M; Spanier, S; Yang, Z C; York, A; Asaadi, J; Aurisano, A; Eusebi, R; Golyash, A; Gurrola, A; Kamon, T; Nguyen, C N; Pivarski, J; Safonov, A; Sengupta, S; Toback, D; Weinberger, M; Akchurin, N; Berntzon, L; Gumus, K; Jeong, C; Kim, H; Lee, S W; Popescu, S; Roh, Y; Sill, A; Volobouev, I; Washington, E; Wigmans, R; Yazgan, E; Engh, D; Florez, C; Johns, W; Pathak, S; Sheldon, P; Andelin, D; Arenton, M W; Balazs, M; Boutle, S; Buehler, M; Conetti, S; Cox, B; Hirosky, R; Ledovskoy, A; Neu, C; Phillips II, D; Ronquest, M; Yohay, R; Gollapinni, S; Gunthoti, K; Harr, R; Karchin, P E; Mattson, M; Sakharov, A; Anderson, M; Bachtis, M; Bellinger, J N; Carlsmith, D; Crotty, I; Dasu, S; Dutta, S; Efron, J; Feyzi, F; Flood, K; Gray, L; Grogg, K S; Grothe, M; Hall-Wilton, R; Jaworski, M; Klabbers, P; Klukas, J; Lanaro, A; Lazaridis, C; Leonard, J; Loveless, R; Magrans de Abril, M; Mohapatra, A; Ott, G; Polese, G; Reeder, D; Savin, A; Smith, W H; Sourkov, A; Swanson, J; Weinberg, M; Wenman, D; Wensveen, M; White, A

2010-01-01

The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47 microns to 243 microns. The efficiencies for local charged track triggers, for hit and for segments reconstruction were measured, and are above 99%. The timing resolution per layer is approximately 5 ns.

Study on pulsed current cathodic protection in a simulated system

Energy Technology Data Exchange (ETDEWEB)

Yan, Milin; Li, Helin [Xi' an Jiao Tong Universitiy (China)]|[Tubular Goods Research Center of China National Petroleum Corp. (China); Qiu, Yubing; Guo, Xingpeng [Hua Zhong University of Science and Techonology (China)

2004-07-01

The pulsed current cathodic protection (PCCP) is a new cathodic protection (CP) technology and shows more advantages over the conventional DC cathodic protection (DCCP) in oil well casing system. However, little information about PCCP is reported. In this research, a simulated CP system was set up in a pool of 3.5 m x 2.0 m x 3.0 m size, in which the effects of the square wave pulsed current (SWPC) parameters (amplitude: IA, frequency: f, duty cycle: P), auxiliary anode distance (d) and media conductivity ({mu}) on the cathodic potential (E) distribution were studied, and the protection effects of PCCP and DCCP were compared. The results show that with increase of the square wave parameters (IA, f, P), the E distribution becomes more negative and the effects of each current parameter are relate closely to the cathode polarizing state. Only with suitable square wave parameters can the whole cathode be effectively protected. With increase of d and {mu}, the E distribution becomes more uniform. Compared with DCCP system, PCCP system has much more uniform E distribution, costs less average current, and gains much better protection effects. Further, the mechanism of PCCP was analyzed. (authors)

Monolithic front-end ICs for interpolating cathode pad and strip detectors for GEM

International Nuclear Information System (INIS)

O'Connor, P.

1993-05-01

We are developing CMOS circuits for readout of interpolating cathode strip and pad chambers for the GEM experiment at the SSC. Because these detectors require position resolution of about 1% of the strip pitch, the electronic noise level must be less than 2000 electrons. Several test chips have been fabricated to demonstrate the feasibility of achieving the combination of low noise, speed, and wide dynamic range in CMOS. Results to date show satisfactory noise and linearity performance. Future development will concentrate on radiation-hardening the central tracker ASIC design, optimizing the shaper peaking time and noise contribution, providing more user-configurable output options, and packaging and test issues

Studies on pulsed hollow cathode capillary discharges

Energy Technology Data Exchange (ETDEWEB)

Choi, P; Dumitrescu-Zoita, C; Larour, J; Rous, J [Ecole Polytechnique, 91 - Palaiseau (France). Lab. de Physique des Milieux Ionises; Favre, M; Moreno, J; Chuaqui, H; Wyndham, E [Pontificia Univ. Catolica de Chile, Santiago (Chile). Facultad de Fisica; Zambra, M [Comision Chilena de Energia Nuclear, Santiago (Chile); Wong, C S [Univ. of Malaya, Kuala Lumpur (Malaysia). Plasma Research Lab

1997-12-31

Preliminary results on radiation characteristics of pulsed hollow cathode capillary discharges are presented. The device combines the on axis electron beam assisted ionization capabilities of the transient hollow cathode discharge with a novel high voltage low inductance geometrical design, which integrates the local energy storage into the electrode system. A nanosecond regime high temperature plasma is produced in a long, high aspect ratio capillary, with light emission in the UV to XUV region. The discharge is operated from near vacuum to pressure in the 1000 mTorr range. (author). 2 figs., 7 refs.

Copper-based electrochemical sensor with palladium electrode for cathodic stripping voltammetry of manganese.

Science.gov (United States)

Kang, Wenjing; Pei, Xing; Bange, Adam; Haynes, Erin N; Heineman, William R; Papautsky, Ian

2014-12-16

In this work, we report on the development of a palladium-based, microfabricated point-of-care electrochemical sensor for the determination of manganese using square wave cathodic stripping voltammetry. Heavy metals require careful monitoring, yet current methods are too complex for a point-of-care system. Voltammetry offers an attractive approach to metal detection on the microscale, but traditional carbon, gold, or platinum electrodes are difficult or expensive to microfabricate, preventing widespread use. Our sensor uses palladium working and auxiliary electrodes and integrates them with a copper-based reference electrode for simple fabrication and compatibility with microfabrication and printed circuit board processing, while maintaining competitive performance in electrochemical detection. Copper electrodes were prepared on glass substrate using a combination of microfabrication procedures followed by electrodeposition of palladium. The disposable sensor system was formed by bonding a poly(dimethylsiloxane) (PDMS) well to the glass substrate. Cathodic stripping voltammetry of manganese using our new disposable palladium-based sensors exhibited 334 nM (18.3 ppb) limit of detection in borate buffer. The sensor was used to demonstrate manganese determination in natural water samples from a pond in Burnet Woods, located in Cincinnati, OH, and the Ohio River.

Linear read out electronics associated with MWPC cathode strips

International Nuclear Information System (INIS)

Hrisoho, A.; Truong, K.

1979-10-01

Low-cost linear chain for MWPC cathode strip charge read-out is described. Some simple relations for noise calculation of the preamplifier (which is a fast low-noise current amplifier) are given. Due to space restriction on the detector, hybrid technique for the preamplifier realization is adopted. The problem of transmission of linear signals (60 m) using twisted pairs, are discussed. 0.2% of cross-talk is achieved. Fast differential input line receiver with shortening filter is used in order to compensate the integration of the transmission line. The cross-talk and the noise pick-up are reduced by assuming a good symmetry and using charge sensing ADC for digitalization of the analog signal

SQUARE WAVE CATHODIC STRIPPING VOLTAMMETRY ADSORPTIVE FOR NICKEL AND COBALT ANALYSIS

Directory of Open Access Journals (Sweden)

Saryati Saryati

2010-06-01

Full Text Available The adsorptive stripping voltammetric determination of Ni and Co based on adsorption of the Ni/Co and dimethylglioxime (DMG complex on a hanging mercury drop electrode is studied. The reduction current of the adsorbed DMG complex is measured by square wave cathodic stripping voltammetry method. The effect of various parameters such as ligand concentration, pH of supporting electrolytic, adsorption potential and adsorption time on the current peak of Ni and Co voltammogram were studied. Optimum condition of this method are supporting electrolyte pH 9, DMG concentration 5×10 -4 M, adsorption potential -0.7 V vs Ag/AgCl and adsorption time 180 second. A linier relationship between the current peak and Ni or Co concentration was obtained in the range 5 - 30 ng/mL and the detection limit 0.6 ng/ml for both Ni and Co. The recovery of Ni and Co were 98.11-104.17% using standard biological materials with RSD 2.59 - 10.37%. Based on ";t"; test can be conclude that the result are nearly equal to the standard reference material.   Keywords: adsorptive stripping voltammetric, dimethylglioxime complex, nickel, cobalt

Cathodic stripping voltammetric determination of arsenic in sugarcane brandy at a modified carbon nanotube paste electrode.

Science.gov (United States)

Teixeira, Meryene C; Tavares, Elisângela de F L; Saczk, Adelir A; Okumura, Leonardo L; Cardoso, Maria das Graças; Magriotis, Zuy M; de Oliveira, Marcelo F

2014-07-01

We have developed an eletroanalytical method that employs Cu(2+) solutions to determine arsenic in sugarcane brandy using an electrode consisting of carbon paste modified with carbon nanotubes (CNTPE) and polymeric resins. We used linear sweep (LSV) and differential-pulse (DPV) voltammetry with cathodic stripping for CNTPE containing mineral oil or silicone as binder. The analytical curves were linear from 30 to 110μgL(-1) and from 10 to 110μgL(-1) for LSV and DPV, respectively. The limits of detection (L.O.D.) and quantification (L.O.Q.) of CNTPE were 10.3 and 34.5μgL(-1) for mineral oil and 3.4 and 11.2μgL(-1) for silicone. We applied this method to determine arsenic in five commercial sugarcane brandy samples. The results agreed well with those obtained by hydride generation combined with atomic absorption spectrometry (HG AAS). Copyright © 2014 Elsevier Ltd. All rights reserved.

Monte Carlo studies on Cathode Strip/Pad Chambers for the ALICE Di-Muon Arm

Energy Technology Data Exchange (ETDEWEB)

Wurzinger, R.; Le Bornec, Y.; Willis, N.

1996-04-01

A general overview about the properties of Cathode Strip and Pad Chambers is given. Position finding methods are discussed and compared within Monte Carlo studies. Noise contributions and their minimization are discussed. Pad chambers allow a two-dimensional readout with spatial resolution of {sigma} < 100 {mu}m in direction parallel to the anode wire. The resolution normal to the anode wire depends mainly on the wire spacing. Special attention is paid on the double-hit resolution capability of the pad chamber. An outlook is given on the possible utilisation of Cathode Pad Chambers in the Di-Muon Arm of the ALICE detector at LHC. (author). 44 refs.

Effects of cathode pulse at low frequency on the structure and composition of plasma electrolytic oxidation ceramic coatings

International Nuclear Information System (INIS)

Yao Zhongping; Xu Yongjun; Jiang Zhaohua; Wang Fuping

2009-01-01

The aim of this work is to investigate the effects of the cathode pulse under the low working frequency on the structure and the composition of the ceramic coatings on Ti-6Al-4V alloys by plasma electrolytic oxidation (PEO). Ceramic coatings were prepared on Ti alloy by pulsed bi-polar plasma electrolytic oxidation in NaAlO 2 solution. The phase composition, morphology, and element distribution in the coating were investigated by X-ray diffractometry, scanning electron microscopy, and energy distribution spectroscopy. The coating was mainly composed of a large amount of Al 2 TiO 5 and a little α-Al 2 O 3 and rutile TiO 2 . Increasing the cathode pulse, the amount of rutile TiO 2 was increased while the amount of Al 2 O 3 was decreased; and decreasing the cathode pulse, the amount of Al 2 O 3 was increased while the amount of rutile TiO 2 was decreased. The thickness of the coatings was increased and then decreased with the increase of the cathode pulse. The grain sizes of Al 2 TiO 5 were increased with the cathode current densities, but changed little with the cathode pulse width. The grain size of α-Al 2 O 3 was decreased with the decrease of the cathode pulse, while the grain size of TiO 2 was increased with the increase of the cathode pulse. The proper cathode pulse was helpful to reduce the roughness and to increase the density of the coatings.

Simultaneous determination of copper, lead and cadmium by cathodic adsorptive stripping voltammetry using artificial neural network

International Nuclear Information System (INIS)

Ensafi, Ali A.; Khayamian, T.; Benvidi, A.; Mirmomtaz, E.

2006-01-01

In this work, simultaneous determination of two groups of elements consisting of Pb(II)-Cd(II) and Cu(II)-Pb(II)-Cd(II) using adsorptive cathodic stripping voltammetry are described. The method is based on accumulation of these metal ions on mercury electrode using xylenol orange as a suitable complexing agent. The potential was scanned to the negative direction and the differential pulse stripping voltammograms were recorded. The instrumental and chemical factors were optimized using artificial neural network. The optimized conditions were obtained in pH of 5.5, xylenol orange concentration of 4.0 μM, accumulation potential of -0.50 V, accumulation time of 30 s, scan rate of 10 mV/s and pulse height of 70 mV. The relationship between the peak current versus concentration was linear over the range of 5.0-150.0 ng ml -1 for cadmium and 5.0-150.0 ng ml -1 for lead. The limits of detection were 0.98 and 1.18 ng ml -1 for lead and cadmium ions, respectively. In simultaneous determination of Cu(II), Pb(II) and Cd(II) there are inter-metallic interactions, which result a non-linear relationship between the peak current and the ionic concentration for each of the element. Therefore, an artificial neural network was used as the multivariate calibration method. The ANN was constructed with three neurons as the output layer for the simultaneous determination of the three elements. The constructed model was able to predict the concentration of the elements in the ranges of 1.0-50.0, 5.0-200.0 and 10.0-200.0 ng ml -1 , for Cu(II), Pb(II) and Cd(II), respectively

Expert System for the LHC CMS Cathode Strip Chambers (CSC) detector

Energy Technology Data Exchange (ETDEWEB)

Rapsevicius, Valdas, E-mail: valdas.rapsevicius@cern.ch [Fermi National Accelerator Laboratory, Batavia, IL (United States); Vilnius University, Didlaukio g. 47-325, LT-08303 Vilnius (Lithuania); Juska, Evaldas, E-mail: evaldas.juska@cern.ch [Fermi National Accelerator Laboratory, Batavia, IL (United States)

2014-02-21

Modern High Energy Physics experiments are of high demand for a generic and consolidated solution to integrate and process high frequency data streams by applying experts' knowledge and inventory configurations. In this paper we present the Expert System application that was built for the Compact Muon Solenoid (CMS) Cathode Strip Chambers (CSC) detector at the Large Hadron Collider (LHC) aiming to support the detector operations and to provide integrated monitoring. The main building blocks are the integration platform, rule-based complex event processing engine, ontology-based knowledge base, persistent storage and user interfaces for results and control.

Effects of pulse-length and emitter area on virtual cathode formation in electron guns

International Nuclear Information System (INIS)

Valfells, Agust; Feldman, D.W.; Virgo, M.; O'Shea, P.G.; Lau, Y.Y.

2002-01-01

Recent experiments at the University of Maryland using photoemission from a dispenser cathode have yielded some interesting results regarding the effects of the area of emission and of the ratio between the pulse length and the gap transit time on the amount of current that may be drawn from an electron gun before a virtual cathode forms. The experiments show that a much higher current density may be drawn from a short pulse or limited emitter area than is anticipated by the Child-Langmuir limiting current. There is also evidence that the current may be increased even after virtual cathode formation, which leads a distinction between a limiting current density and a current density critical for virtual cathode formation. The experiments have also yielded some interesting results on the longitudinal structure of the current pulse passed through the anode. Some empirical and theoretical scaling laws regarding the formation of virtual cathodes in an electron gun will be presented. This work was motivated by the needs of the University of Maryland Electron Ring (UMER) [P. G. O'Shea, M. Reiser, R. A. Kishek et al., Nucl. Instrum. Methods Phys. Res. A 464, 646 (2001)] where the goal is to generate pulses that are well-localized in time and space

Space and time dependent properties of the virtual cathode in a reflex-type pulsed ion diode (virtual cathode in a reflex-type pulsed ion diode)

International Nuclear Information System (INIS)

Matsumoto, Yoshio; Yano, Syukuro

1982-01-01

Properties of a virtual cathode in a pulsed ion diode composed of an insulator-mesh anode and a metal-mesh cathode were studied experimentally at anode voltages below 360kV. Potential distribution in the virtual cathode side was measured with an insulated electrostatic potential probe, and ion beam currents in virtual and real cathode sides were measured with biased ion collectors. A loss parameter for the electron current at the virtual cathode was evaluated from the measured electron current values by using relations derived from the one-dimensional Child-Langmuir theory applied to the reflex triode. The ion beam accompanies a considerable amount of electron current, and this influences the stability of the virtual cathode; this perturbation results in variations of ion current with time. Space potentials in the emitted ion beam are given, suggesting an existence of high energy electrons of several keV accelerated by positive space potential of the ion beam. (author)

Multiphoton photoemission from a copper cathode illuminated by ultrashort laser pulses in an RF photoinjector.

Science.gov (United States)

Musumeci, P; Cultrera, L; Ferrario, M; Filippetto, D; Gatti, G; Gutierrez, M S; Moody, J T; Moore, N; Rosenzweig, J B; Scoby, C M; Travish, G; Vicario, C

2010-02-26

In this Letter we report on the use of ultrashort infrared laser pulses to generate a copious amount of electrons by a copper cathode in an rf photoinjector. The charge yield verifies the generalized Fowler-Dubridge theory for multiphoton photoemission. The emission is verified to be prompt using a two pulse autocorrelation technique. The thermal emittance associated with the excess kinetic energy from the emission process is comparable with the one measured using frequency tripled uv laser pulses. In the high field of the rf gun, up to 50 pC of charge can be extracted from the cathode using a 80 fs long, 2 microJ, 800 nm pulse focused to a 140 mum rms spot size. Taking into account the efficiency of harmonic conversion, illuminating a cathode directly with ir laser pulses can be the most efficient way to employ the available laser power.

Multiphoton Photoemission from a Copper Cathode Illuminated by Ultrashort Laser Pulses in an rf Photoinjector

International Nuclear Information System (INIS)

Musumeci, P.; Gutierrez, M. S.; Moody, J. T.; Moore, N.; Rosenzweig, J. B.; Scoby, C. M.; Travish, G.; Cultrera, L.; Ferrario, M.; Filippetto, D.; Gatti, G.; Vicario, C.

2010-01-01

In this Letter we report on the use of ultrashort infrared laser pulses to generate a copious amount of electrons by a copper cathode in an rf photoinjector. The charge yield verifies the generalized Fowler-Dubridge theory for multiphoton photoemission. The emission is verified to be prompt using a two pulse autocorrelation technique. The thermal emittance associated with the excess kinetic energy from the emission process is comparable with the one measured using frequency tripled uv laser pulses. In the high field of the rf gun, up to 50 pC of charge can be extracted from the cathode using a 80 fs long, 2 μJ, 800 nm pulse focused to a 140 μm rms spot size. Taking into account the efficiency of harmonic conversion, illuminating a cathode directly with ir laser pulses can be the most efficient way to employ the available laser power.

A New Segment Building Algorithm for the Cathode Strip Chambers in the CMS Experiment

Directory of Open Access Journals (Sweden)

Golutvin I.

2016-01-01

Full Text Available A new segment building algorithm for the Cathode Strip Chambers in the CMS experiment is presented. A detailed description of the new algorithm is given along with a comparison with the algorithm used in the CMS software. The new segment builder was tested with different Monte-Carlo data samples. The new algorithm is meant to be robust and effective for hard muons and the higher luminosity that is expected in the future at the LHC.

Gravity sag of sandwich panel assemblies as applied to precision cathode strip chamber structural design

International Nuclear Information System (INIS)

Horvath, J.

1993-01-01

The relationship between gravity sag of a precision cathode strip chamber and its sandwich panel structural design is explored parametrically. An algorithm for estimating the dominant component of gravity sag is defined. Graphs of normalized gravity sag as a function of gap frame width and material, sandwich core edge filler width and material, panel skin thickness, gap height, and support location are calculated using the gravity sag algorithm. The structural importance of the sandwich-to-sandwich ''gap frame'' connection is explained

Completion of cathode strip chamber (CSC) installation on the so-called YE+2 wheel of CMS on March 2005.

CERN Multimedia

Tejinder S. Virdee

2005-01-01

The pictures have been taken in the CMS construction hall in Cessy (neighbouring France), called SX5, in March 2005 and show the status of cathode strip chamber (CSC) assembly on the yoke disk YE+2. The chambers are labelled ME+3 and their installation has been completed on March 16th, 2005.

Non-invasive characterization and quality assurance of silicon micro-strip detectors using pulsed infrared laser

Science.gov (United States)

Ghosh, P.

2016-01-01

The Compressed Baryonic Matter (CBM) experiment at FAIR is composed of 8 tracking stations consisting of roughly 1300 double sided silicon micro-strip detectors of 3 different dimensions. For the quality assurance of prototype micro-strip detectors a non-invasive detector charaterization is developed. The test system is using a pulsed infrared laser for charge injection and characterization, called Laser Test System (LTS). The system is aimed to develop a set of characterization procedures which are non-invasive (non-destructive) in nature and could be used for quality assurances of several silicon micro-strip detectors in an efficient, reliable and reproducible way. The procedures developed (as reported here) uses the LTS to scan sensors with a pulsed infra-red laser driven by step motor to determine the charge sharing in-between strips and to measure qualitative uniformity of the sensor response over the whole active area. The prototype detector modules which are tested with the LTS so far have 1024 strips with a pitch of 58 μm on each side. They are read-out using a self-triggering prototype read-out electronic ASIC called n-XYTER. The LTS is designed to measure sensor response in an automatized procedure at several thousand positions across the sensor with focused infra-red laser light (spot size ≈ 12 μm, wavelength = 1060 nm). The pulse with a duration of ≈ 10 ns and power ≈ 5 mW of the laser pulse is selected such, that the absorption of the laser light in the 300 μm thick silicon sensor produces ≈ 24000 electrons, which is similar to the charge created by minimum ionizing particles (MIP) in these sensors. The laser scans different prototype sensors and various non-invasive techniques to determine characteristics of the detector modules for the quality assurance is reported.

Li2S/Carbon Nanocomposite Strips from a Low-Temperature Conversion of Li2SO4 as High-Performance Lithium-Sulfur Cathodes

Energy Technology Data Exchange (ETDEWEB)

Ye, Fangmin; Noh, Hyungjun; Lee, Jin Hong; Lee, Hongkyung; Kim, Hee-Tak

2018-03-12

Carbothermal conversion of Li2SO4 provides a cost-effective strategy to fabricate high-capacity Li2S cathodes, however, Li2S cathodes derived from Li2SO4 at high temperatures (> 800 oC), having high crystallinity and large crystal size, result in a low utilization of Li2S. Here, we report a Li2SO4/poly(vinyl alcohol)-derived Li2S/Carbon nanocomposite (Li2S@C) strips at a record low temperature of 635 oC. These Li2S@C nanocomposite strips as a cathode shows a low initial activation potential (2.63 V), a high initial discharge capacity (805 mAh g-1 Li2S) and a high cycling stability (0.2 C and 1 C). These improvedresults could be ascribed to the nano-sized Li2S particles as well as their low crystallinity due to the PVA-induced carbon network and the low conversion temperature, respectively. An XPS analysis reveals that the C=C and C=O bonds derived from the carbonization of PVA can promote the conversion of Li2SO4 at the low temperature.

Ampère-Class Pulsed Field Emission from Carbon-Nanotube Cathodes in a Radiofrequency Resonator

Energy Technology Data Exchange (ETDEWEB)

Mihalcea, D. [Northern Illinois U.; Faillace, L. [RadiaBeam Tech.; Hartzell, J. [RadiaBeam Tech.; Panuganti, H. [Northern Illinois U.; Boucher, S. M. [RadiaBeam Tech.; Murokh, A. [RadiaBeam Tech.; Piot, P. [Fermilab; Thangaraj, J. C.T. [Fermilab

2014-12-01

Pulsed field emission from cold carbon-nanotube cathodes placed in a radiofrequency resonant cavity was observed. The cathodes were located on the backplate of a conventional $1+\\frac{1}{2}$-cell resonant cavity operating at 1.3-GHz and resulted in the production of bunch train with maximum average current close to 0.7 Amp\\`ere. The measured Fowler-Nordheim characteristic, transverse emittance, and pulse duration are presented and, when possible, compared to numerical simulations. The implications of our results to high-average-current electron sources are briefly discussed.

Effects of cathode pulse at high frequency on structure and composition of Al2TiO5 ceramic coatings on Ti alloy by plasma electrolytic oxidation

International Nuclear Information System (INIS)

Yao Zhongping; Liu Yunfu; Xu Yongjun; Jiang Zhaohua; Wang Fuping

2011-01-01

Research highlights: → Al 2 TiO 5 in the coating on Ti alloy by PEO treatment changes with the increase of the cathode pulse, regardless of the amount and the grain size. → The cathode pulse brings about the decrease of γ-Al 2 O 3 and the increase of rutile TiO 2 in the coating. → The appropriate cathode pulse during PEO process is beneficial to reduce residual discharging channels and improve the density of the coating. - Abstract: The aim of this work is to investigate the effects of cathode pulse under high working frequency on structure and composition of ceramic coatings on Ti-6Al-4V alloys by plasma electrolytic oxidation (PEO). Ceramic coatings were prepared on Ti alloy by pulsed bi-polar plasma electrolytic oxidation in NaAlO 2 solution. The phase composition, morphology and element distribution in the coating were investigated by X-ray diffractometry, scanning electron microscopy and energy distribution spectroscopy, respectively. The coating was mainly composed of a large amount of Al 2 TiO 5 . As the cathode pulse was increased, the amount and grain size of Al 2 TiO 5 were first increased, and then decreased. γ-Al 2 O 3 in the coating was gradually decreased to nothing with the increase in the cathode pulse whereas rutile TiO 2 began to form in the coating. As opposed to the single-polar anode pulse mode, the cathode pulse reduced the thickness of the coatings. However, as the cathode pulse intensity continued to increase, the coating then became thicker regardless of cathode current density or pulse width. In addition, the residual discharging channels were reduced and the density of the coating was increased with the appropriate increase of the cathode pulse.

Plasma source ion implantation of metal ions: Synchronization of cathodic-arc plasma production and target bias pulses

International Nuclear Information System (INIS)

Wood, B.P.; Reass, W.A.; Henins, I.

1995-01-01

An erbium cathodic-arc has been installed on a Plasma Source Ion Implantation (PSII) experiment to allow the implantation of erbium metal and the growth of adherent erbia (erbium oxide) films on a variety of substrates. Operation of the PSII pulser and the cathodic-arc are synchronized to achieve pure implantation, rather than the hybrid implantation/deposition being investigated in other laboratories. The relative phase of the 20 μs PSII and cathodic-arc pulses can to adjusted to tailor the energy distribution of implanted ions and suppress the initial high-current drain on the pulse modulator. The authors present experimental data on this effect and make a comparison to results from particle-in-cell simulations

An environmental friendly electrode and extended cathodic potential window for anodic stripping voltammetry of zinc detection

International Nuclear Information System (INIS)

Dueraning, Anisah; Kanatharana, Proespichaya; Thavarungkul, Panote; Limbut, Warakorn

2016-01-01

This work reports on a novel polyeriochrome black T (poly(EBT) modified electrode for use as an environmentally-friendly electrode material that extends the cathodic potential window and improves the sensitivity and repeatability to detect zinc in industrial wastewater. The poly(EBT) film on the GCE surface was fabricated by electropolymerization. The surface morphology and electrochemical behavior of the modified electrode were characterized by scanning electron microscopy, fourier transform infrared spectroscopy and anodic stripping voltammetry. Under optimal conditions, the poly(EBT)/GCE exhibited a high hydrogen overvoltage (extended cathodic potential window). It provided a high sensitivity, a wide linear range (1.0 to 400.0 μg L −1 ), a low detection limit (0.9 μg L −1 ), had excellent repeatability and good recoveries (95% to 105%). This proposed modified electrode was applied to the determination of zinc in wastewater samples, and the results were consistent with those of an inductively coupled plasma atomic emission spectroscopy analysis.

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

International Nuclear Information System (INIS)

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

2016-01-01

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

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).

Transient voltage response of a superconducting strip to a supercritical current pulse

International Nuclear Information System (INIS)

Attekum, P.M.Th.M. van; Wouters, M.C.H.M.; Wolter, J.; Horstman, R.E.

1981-01-01

A superconductor subject to a supercritical current pulse displays a delay time between the onset of the current pulse and the onset of the corresponding voltage response. From the onset of the voltage response it takes a second (transient) time to reach the stationary state. It is shown that the transient time can be explained with inhomogeneities in the strip which give rise to a distribution of delay times. The transient time is thus not related to a characteristic time in the superconductor. For small supercritical currents also heating effects show up. (author)

Uranium vapor generator: pulsed hollow cathode lamp

International Nuclear Information System (INIS)

Carleer, M.; Gagne, J.; Leblanc, B.; Demers, Y.; Mongeau, B.

1979-01-01

The production of uranium vapors has been studied in the 5 L 0 6 ground state using a pulsed hollow cathode lamp. The evolution of the 238 U ( 5 L 0 6 ) concentration with time has been studied with Xe and Ar as buffer gases. A density of 2.7 x 10 13 atoms cm -3 was obtained with Xe as a buffer gas. In addition, those measurements, obtained from the absorption of a laser beam tuned to the 5758.143 A ( 5 L 0 6 -17,361 7 L 6 ) transition, allowed the determination of the transition probability A=2.1 x 10 5 sec -1 and of the branching ratio BR=0.08 for this transition

Corrosion and protection in reinforced concrete : Pulse cathodic protection: an improved cost-effective alternative

NARCIS (Netherlands)

Koleva, D.A.

2007-01-01

Corrosion and protection in reinforced concrete. Pulse cathodic protection: an improved cost-effective alternative. The aim of the research project was to study the possibilities for establishing a new or improved electrochemical method for corrosion prevention/protection for reinforced concrete.

DIFFERENTIAL PULSE ANODIC STRIPPING VOLTAMMETRY FOR DETERMINATION OF SOME HEAVY METALS IN URANIUM

Directory of Open Access Journals (Sweden)

Saryati Saryati

2010-06-01

Full Text Available The direct determination of some metals impurity in uranium by using differential pulse anodic stripping voltammetry (DPASV method at a hanging mercury drop electrode and in a carbonate buffer media was developed. It was found that the carbonate buffer show the strongest affinity for uranium and gives the best separation between the DPASV peaks of heavy metals impurities. The carbonate concentration markedly affects the oxidation and reduction the major and the minor constituents of the uranium samples. In 0.1 M carbonate buffer solution pH 10, copper, bismuth, thalium, lead, cadmium, zinc, could be determined without the removal of the uranium matrix. Recovery and relative standard deviation (RSD of this method was in the range of 174% - 85.2% for recovery and 36.8% - 1.2% for RSD. The larger error of analytical result was obtained for Zn at low concentration. In general, the analytic results error and RSD decreased with increasing metals concentration.   Keywords: heavy metal determination, differential pulse anodic stripping voltammetry, uranium

Pulsed Electron Source with Grid Plasma Cathode and Longitudinal Magnetic Field for Modification of Material and Product Surfaces

Science.gov (United States)

Devyatkov, V. N.; Koval, N. N.

2018-01-01

The description and the main characteristics of the pulsed electron source "SOLO" developed on the basis of the plasma cathode with grid stabilization of the emission plasma boundary are presented. The emission plasma is generated by a low-pressure arc discharge, and that allows to form the dense low-energy electron beam with a wide range of independently adjustable parameters of beam current pulses (pulse duration of 20-250 μs, pulse repetition rate of 1-10 s-1, amplitude of beam current pulses of 20-300 A, and energy of beam electrons of 5-25 keV). The special features of generation of emission plasma by constricted low-pressure arc discharge in the grid plasma cathode partially dipped into a non-uniform magnetic field and of formation and transportation of the electron beam in a longitudinal magnetic field are considered. The application area of the electron source and technologies realized with its help are specified.

High precision straw tube chamber with cathode readout

International Nuclear Information System (INIS)

Bychkov, V.N.; Golutvin, I.A.; Ershov, Yu.V.

1992-01-01

The high precision straw chamber with cathode readout was constructed and investigated. The 10 mm straws were made of aluminized mylar strip with transparent longitudinal window. The X coordinate information has been taken from the cathode strips as induced charges and investigated via centroid method. The spatial resolution σ=120 μm has been obtained with signal/noise ratio about 60. The possible ways for improving the signal/noise ratio have been described. 7 refs.; 8 figs

Practical measurement of silicon in low alloy steels by differential pulse stripping voltammetry

International Nuclear Information System (INIS)

Rahier, A.; Lunardi, S.; Triki, C.

2005-01-01

A sensitive differential pulse anodic stripping voltammetry has been adapted to allow the determination of Si in low-alloy steels using a hanging mercury drop electrode. The method has been qualified using certified ASTM standards and is now running in routine. The present report describes the experimental details, thereby allowing the reader to carry out the measurements precisely. (author)

Upgrade of the cathode strip chamber level 1 trigger optical links at CMS

International Nuclear Information System (INIS)

Ecklund, K; Liu, J; Matveev, M; Padley, P; Madorsky, A

2012-01-01

At the Large Hadron Collider (LHC) at CERN, the CMS experiment's Level 1 Trigger system for the endcap Cathode Strip Chambers (CSC) has 180 optical links to transmit Level 1 trigger primitives from 60 peripheral crates to the CSC Track Finder (CSCTF) which reconstructs muon candidates. Currently there is a limit of 3 trigger primitives per crate serving a cluster of 9 chambers. With the anticipated LHC luminosity increase up to 10 35 cm −2 s −1 at full energy of 7 TeV/beam the Muon Port Card (MPC), which transmits the primitives, the receiver in the CSCTF (Sector Processor) and the optical transmission system itself need to be upgraded. At the same time it is very desirable to preserve all the old optical links intact for compatibility with the present Track Finder during transition period. We present here the results of our efforts in the past two years to upgrade the MPC board, including the hardware developments, data transmission tests and latency measurements.

Rapid temperature increase near the anode and cathode in the afterglow of a pulsed positive streamer discharge

Science.gov (United States)

Ono, Ryo

2018-06-01

The spatiotemporal evolution of the temperature in the afterglow of point-to-plane, pulsed positive streamer discharge was measured near the anode tip and cathode surface using laser-induced predissociation fluorescence of OH radicals. The temperature exhibited a rapid increase and displayed a steep spatial gradient after a discharge pulse. The rate of temperature rise reached 84 K μs‑1 at mm, where z represents the distance from the anode tip. The temperature rise was much faster than in the middle of the gap; it was only 2.8 K μs‑1 at mm. The temperature reached 1700 K near the anode tip at s and 1500 K near the cathode surface at s, where t represents the postdischarge time. The spatial gradient reached 1280 K mm‑1 near the anode tip at s. The mechanism responsible for the rapid temperature increase was discussed, including rapid heating of the gas in the early postdischarge phase (s), and vibration-to-translation energy transfer in the later postdischarge phase (s). The high temperatures near the anode tip and cathode surface are particularly important for the ignition of combustible mixtures and for surface treatments, including solid-surface treatments, water treatments, and plasma medicine using pulsed streamer discharges.

1 ms pulse beam generation and acceleration by photo-cathode RF gun

International Nuclear Information System (INIS)

Watanabe, Ken; Hayano, Hitoshi; Urakawa, Jyunji

2012-01-01

We report successful generation of 1 ms long pulse and multi-bunch electron beam by a normal conducting photo-cathode RF gun at KEK-STF (Superconducting accelerator Test Facility). The 1 ms long Pulse beam generated by the RF gun is delivered to the injection line to examine stable acceleration and precise RF control. The 1 ms pulse beam is also used to demonstrate high brightness X-ray generation by inverse laser Compton scattering which will be also carried out at STF, supported by MEXT Quantum Beam project. The RF gun cavity has been fabricated by DESY-FNAL-KEK collaboration. Performing high power RF process and ethanol rinse to the cavity, a stable operation of the cavity up to 4.0 MW RF input power with ∼1 ms pulse length was achieved by keeping even low dark current. The beam generation test has been started since February 2012, 1 ms pulse was generated in March 2012. We explain about the STF injector and report the basic property of this 1 ms beam generation. (author)

Cathode material and pulsed plasma treatment influence on the microstructure and microhardness of high-chromium cast iron surface

Directory of Open Access Journals (Sweden)

Юлія Геннадіївна Чабак

2016-11-01

Full Text Available The article presents an analysis of the cathode material and the pulse plasma treatment mode influence on the surface microstructure and microhardness of high chrome (15% Cr cast iron. The methods of metallographic analysis and microhardness measurements were used. It has been shown that pulsed plasma treatment at 4 kV voltage with the use of the electro-axial thermal accelerator results in surface modification with high microhardness 950-1050 HV50, and in the formation of the coating due to the transfer of the electrodes material. The specific features of using different cathode materials have been systematized. It has been found that graphite electrodes are not recommended to be used due to their low strength and fracture under plasma pulses. In case of using tungsten cathode a coating of small thickness (20-30 microns and having cracks has been formed on the specimen surface. The most expedient is to apply the electrodes with low melting point (such as killed St.3, which provides a high-quality state of treated surface and formation the protective crack-free coating of 80-100 microns thick. It has been found that as a result of the plasma pulsed treatment the enrichment of coating with carbon is likely to occur that results in microhardness increase. The prospects of this technology as well as its shortcomings have been described

Performance of CdZnTe strip detectors as sub-millimeter resolution imaging gamma radiation spectrometers

International Nuclear Information System (INIS)

Mayer, M.; Boykin, D.V.; Drake, A.

1996-01-01

We report γ-ray detection performance measurements and computer simulations of a sub-millimeter pitch CdZnTe strip detector. The detector is a prototype for γ-ray astronomy measurements in the range of 20-200 keV. The prototype is a 1.5 mm thick, 64 x 64 orthogonal stripe CdZnTe detector of 0.375 mm pitch in both dimensions, with approximately one square inch of sensitive area. Using discrete laboratory electronics to process signals from 8 x 8 stripe region of the prototype we measured good spectroscopic uniformity and sub-pitch (∼ 0.2 mm) spatial resolution in both x and y dimensions. We present below measurements of the spatial uniformity, relative timing and pulse height of the anode and cathode signals, and the photon detection efficiency. We also present a technique for determining the location of the event in the third dimension (depth). We simulated the photon interactions and signal generation in the strip detector and the test electronics and we compare these results with the data. The data indicate that cathode signal - as well as the anode signal - arises more strongly from the conduction electrons rather than the holes

Cold cathode electron guns in the LASL high power short-pulse CO2 laser program

International Nuclear Information System (INIS)

Singer, S.; Ladish, J.S.; Nutter, M.J.

1975-01-01

The Electron Beam Controlled Discharge CO 2 Laser is now firmly established as the only high power short pulse laser amplifier that has been demonstrated to have scaling capabilities to large apertures and energies much greater than 100 J. These devices require a beam of energetic electrons to control the gas discharge that produces the required population inversion. Until recently, the electron source was usually a thermionic emitter, even for rather large lasers, whose heater requirements dwarfed the pulsed energies associated with the transient operation of the laser. With the advent of reliable cold-cathode electron guns, the operation of these lasers has been greatly simplified. At LASL, there are four electron beam controlled laser systems which are in operation, under construction, or in design: the 1 kJ system, now operational; the 2.5 kJ system; the 10 kJ system; and the 100 kJ system. Only the first uses thermionic-emitter electron guns; the remainder use or will use cold cathode sources. The operation of the 200 x 35 cm 2 two sided cold cathode electron gun used in the 2.5 kJ laser system and to be used in the 10 kJ laser is described

Increase of intrinsic emittance induced by multiphoton photoemission from copper cathodes illuminated by femtosecond laser pulses

Science.gov (United States)

An, Chenjie; Zhu, Rui; Xu, Jun; Liu, Yaqi; Hu, Xiaopeng; Zhang, Jiasen; Yu, Dapeng

2018-05-01

Electron sources driven by femtosecond laser have important applications in many aspects, and the research about the intrinsic emittance is becoming more and more crucial. The intrinsic emittance of polycrystalline copper cathode, which was illuminated by femtosecond pulses (FWHM of the pulse duration was about 100 fs) with photon energies above and below the work function, was measured with an extremely low bunch charge (single-electron pulses) based on free expansion method. A minimum emittance was obtained at the photon energy very close to the effective work function of the cathode. When the photon energy decreased below the effective work function, emittance increased rather than decreased or flattened out to a constant. By investigating the dependence of photocurrent density on the incident laser intensity, we found the emission excited by pulsed photons with sub-work-function energies contained two-photon photoemission. In addition, the portion of two-photon photoemission current increased with the reduction of photon energy. We attributed the increase of emittance to the effect of two-photon photoemission. This work shows that conventional method of reducing the photon energy of excited light source to approach the room temperature limit of the intrinsic emittance may be infeasible for femtosecond laser. There would be an optimized photon energy value near the work function to obtain the lowest emittance for pulsed laser pumped photocathode.

Space and time dependent properties of the virtual cathode in a reflex-type pulsed ion diode

International Nuclear Information System (INIS)

Matsumoto, Yoshio; Kitamura, Akira; Yano, Syukuro

1981-01-01

Properties of a virtual cathode in a pulsed ion diode composed of and insulator-mesh anode and a metal-mesh cathode were studied experimentally at anode voltages below 35o kV. Potential distribution in the virtual cathode side was measured with an insulated electrostatic potential probe, and ion beam currents in virtual and real cathode sides were measured with biased ion collectors. Experimental results are given for the space and time behaviors of the anode plasma and the virtual cathode which starts to grow first from a region near a periphery of the metal anode frame and extends over the central region near the anode surface. A loss parameter for the electron current accompanied with the ion beam at the virtual cathode was evaluated from the measured electron current values by using relations derived from the one-dimensional Child-Langmuir theory applied to the reflex triode. The ion beam accompanies a considerable amount of electron current, and this influences the stability of the virtual cathode; this perturbation results in variations of ion current with time. Experimental results for space potentials in the emitted ion beam and the total current flowing in the space of the virtual cathode side are also given, suggesting an existence of high energy electrons of several keV accelerated by positive space potential of the ion beam. (author)

Anode front-end electronics for the cathode strip chambers of the CMS Endcap Muon detector

International Nuclear Information System (INIS)

Ferguson, T.; Bondar, N.; Golyash, A.; Sedov, V.; Terentiev, N.; Vorobiev, I.

2005-01-01

The front-end electronics system for the anode signals of the CMS Endcap Muon cathode strip chambers has about 183,000 channels. The purposes of the anode front-end electronics are to acquire precise muon timing information for bunch crossing number identification at the Level-1 muon trigger system and to provide a coarse radial position of the muon track. Each anode channel consists of an input protection network, amplifier, shaper, constant-fraction discriminator, and a programmable delay. The essential parts of the electronics include a 16-channel amplifier-shaper-discriminator ASIC CMP16 and a 16-channel ASIC D16G providing programmable time delay. The ASIC CMP16 was optimized for the large cathode chamber size (up to 3x2.5 m 2 ) and for the large input capacitance (up to 200 pF). The ASIC combines low power consumption (30 mW/channel) with good time resolution (2-3 ns). The delay ASIC D16G makes possible the alignment of signals with an accuracy of 2.2 ns. This paper presents the anode front-end electronics structure and results of the preproduction and the mass production tests, including radiation resistance and reliability tests. The special set of test equipment, techniques, and corresponding software developed and used in the test procedures are also described

Extraction of a long-pulsed intense electron beam from a pulsed plasma based on hollow cathode discharge

International Nuclear Information System (INIS)

Uramoto, Johshin.

1977-05-01

An intense electron beam (up to 1.0 kV, 0.8 kA in 0.8 cm phi) is extracted along a uniform magnetic field with a long decay time (up to 2 msec) from a pulsed high density plasma source which is produced with a fast rise time (< 100 μsec) by a secondary discharge based on a dc hollow cathode discharge. Through a back stream of ionized ions from a beam-extracting anode region where a neutral gas is fed, a space charge limit of the electron beam is so reduced that the beam current is determined by an initially injected electron flux and concentrated in a central aperture of the extracting anode. Moreover, the beam pulse width is much extended by the neutral gas feed into the anode space. (auth.)

Thermal neutron measurements on electrolytic cells with deuterated palladium cathodes subjected to a pulsed current

International Nuclear Information System (INIS)

Granada, J.R.; Mayer, R.E.; Guido, G.; Florido, P.C.; Larreteguy, A.; Gillette, V.H.; Patino, N.E.; Converti, J.; Gomez, S.E.

1990-01-01

The present work describes the design of a high efficiency thermal neutron detection system and the measurements performed with it on electrolytic cells containing LiH dissolved in D 2 O with palladium cathodes. A procedure involving the use of a non-stationary (pulsed) current through the cell caused a correlated neutron production to be observed in a repeatable manner. These patterns are strongly dependent on the previous charging history of the cathodes. The technique employed seems to be very useful as a research tool for a systematic study of the different variables governing the phenomenon. (author)

Characterization of silicon micro-strip sensors with a pulsed infra-red laser system for the CBM experiment at FAIR

Energy Technology Data Exchange (ETDEWEB)

Ghosh, Pradeep [Goethe University, Frankfurt am Main (Germany); GSI Helmholtz Center for Heavy Ion Research GmbH, Darmstadt (Germany); Eschke, Juergen [GSI Helmholtz Center for Heavy Ion Research GmbH, Darmstadt (Germany); Facility for Anti-proton and Ion Research, GmbH, Darmstadt (Germany); Collaboration: CBM-Collaboration

2015-07-01

The Silicon Tracking System (STS) of the CBM experiment at FAIR is composed of 8 tracking stations comprising of 1292 double-sided silicon micro-strip sensors. A Laser Test System (LTS) has been developed for the quality assurance of prototype sensors. The aim is to scan sensors with a pulsed infra-red laser driven by step motor to determine the charge sharing in-between strips and to measure qualitative uniformity of the sensor response over the whole active area. Several prototype sensors with strip pitch of 50 and 58 μm have been tested, as well as a prototype module with realistic mechanical arrangement of sensor and read-out cables. The LTS is designed to measure sensor response in an automatized procedure across the sensor with focused laser beam (spot-size ∼ 12 μm, wavelength = 1060 nm). The pulse with duration (∼ 10 ns) and power (∼ 5 mW) of the laser pulses is selected such, that the absorption of the laser light in the 300 μm thick silicon sensors produces a number of about 24000 electrons, which is similar to the charge created by minimum ionizing particles (MIP) in these sensors. Results from laser scans of prototype sensors and detector module are reported.

TPC cathode read-out with C-pads

International Nuclear Information System (INIS)

Janik, R.; Pikna, M.; Sitar, B.; Strmen, P.; Szarka, I.

2009-01-01

A Time Projection Chamber with 'C' like shaped cathode pads was built and tested. It offers a low gas gain operation, a good pulse shape and a lightweight construction. The Pad Response Function (PRF), the cathode to anode pulse height ratios and the pad pulse shapes of the C-pad structure were measured and compared with planar cathode structures in two different wire geometries. The cathode to anode signal ratio was improved from between 0.2 and 0.4 up to 0.7. The PRF was considerably improved, it has a Gaussian shape and is narrower than in the case of the planar pads. The pulse shape from the C-pad read-out is similar to the pulse shape from a detector with a cylindrical shape of electrodes. A method for aluminum pad mass production based on a precise cold forging was developed and tested.

Nonlinear Dynamics of Ultrashort Long-Range Surface Plasmon Polariton Pulses in Gold Strip Waveguides

DEFF Research Database (Denmark)

Lysenko, Oleg; Bache, Morten; Olivier, Nicolas

2016-01-01

We study experimentally and theoretically nonlinear propagation of ultrashort long-range surface plasmon polaritons in gold strip waveguides. The nonlinear absorption of the plasmonic modes in the waveguides is measured with femtosecond pulses revealing a strong dependence of the third......-order nonlinear susceptibility of the gold core on the pulse duration and layer thickness. A comprehensive model for the pulse duration dependence of the third-order nonlinear susceptibility is developed on the basis of the nonlinear Schrödinger equation for plasmonic mode propagation in the waveguides....... The model accounts for the intrinsic delayed (noninstantaneous) nonlinearity of free electrons of gold as well as the thickness of the gold film and is experimentally verified. The obtained results are important for the development of active plasmonic and nanophotonic components....

Experimental research on time-resolved evolution of cathode plasma expansion velocity in a long pulsed magnetically insulated coaxial diode

Science.gov (United States)

Zhu, Danni; Zhang, Jun; Zhong, Huihuang; Ge, Xingjun; Gao, Jingming

2018-02-01

Unlike planar diodes, separate research of the axial and radial plasma expansion velocities is difficult for magnetically insulated coaxial diodes. Time-resolved electrical diagnostic which is based on the voltage-ampere characteristics has been employed to study the temporal evolution of the axial and radial cathode plasma expansion velocities in a long pulsed magnetically insulated coaxial diode. Different from a planar diode with a "U" shaped profile of temporal velocity evolution, the temporal evolution trend of the axial expansion velocity is proved to be a "V" shaped profile. Apart from the suppression on the radial expansion velocity, the strong magnetic field is also conducive to slowing down the axial expansion velocity. Compared with the ordinary graphite cathode, the carbon velvet and graphite composite cathode showed superior characteristics as judged by the low plasma expansion velocity and long-term electrical stability as a promising result for applications where long-pulsed and reliable operation at high power is required.

The construction and performance of a large cylindrical wire chamber with cathode readout

International Nuclear Information System (INIS)

Deiters, K.; Donat, A.; Friebel, W.; Heller, R.; Kirsch, S.; Krankenhagen, R.; Lange, W.; Leiste, R.; Lohmann, W.; Lustermann, W.; Peng, Y.; Roeser, U.; Tonisch, F.; Trowitzsch, G.; Vogt, H.; Wilhelmi, M.

1991-12-01

The construction and performance of two large coaxial cylindrical multiwire proportional chambers with cathode readout, denoted as Z-Detector, forming the outer part of the L3 central tracking detector, are described. Three self supporting cylinders of about 1 m length and 1 m diameter, constructed as a sandwich of Kapton foil and foam, form the mechanical frame. It represents 2% of a radiation length. In each chamber one cathode layer is subdivided in helical strips and the other one in rings. The readout of the charges induced on the cathode strips and the other one in rings. The readout of the charges induced on the cathode strips provides the avalanche position along the beam (z-) direction. The detector has been running in the L3 experiment at LEP for nearly two years. The resolution of the z-measurement is 320 μm, the double track resolution is about 10 mm. The efficiency of each chamber is 96%. (orig.)

Characterization of silicon micro-strip sensors with a pulsed infra-red laser system for the CBM experiment at FAIR

International Nuclear Information System (INIS)

Ghosh, P.

2015-01-01

The Compressed Baryonic Matter (CBM) experiment at FAIR is composed of 8 tracking stations consisting of 1292 double sided silicon micro-strip sensors. For the quality assurance of produced prototype sensors a laser test system (LTS) has been developed. The aim of the LTS is to scan sensors with a pulsed infra-red laser driven by step motor to determine the charge sharing in-between strips and to measure qualitative uniformity of the sensor response over the whole active area. The prototype sensors which are tested with the LTS so far have 256 strips with a pitch of 50 μm on each side. They are read-out using a self-triggering prototype read-out electronic ASIC called n-XYTER. The LTS is designed to measure sensor response in an automatized procedure at several thousand positions across the sensor with focused infra-red laser light (spot size ≈ 12 μm , wavelength = 1060 nm). The pulse with duration (≈ 10 ns) and power (≈ 5 mW) of the laser pulses is selected such, that the absorption of the laser light in the 300 μm thick silicon sensors produces a number of about 24000 electrons, which is similar to the charge created by minimum ionizing particles (MIP) in these sensors. Laser scans different prototype sensors is reported

Enhanced self-magnetic field by atomic polarization in partially stripped plasma produced by a short and intense laser pulse

International Nuclear Information System (INIS)

Hu Qianglin; Liu Shibing; Jiang, Y.J.; Zhang Jie

2005-01-01

The enhancement and redistribution of a self-generated quasistatic magnetic field, due to the presence of the polarization field induced by partially ionized atoms, are analytically revealed when a linearly polarized intense and short pulse laser propagates in a partially stripped plasma with higher density. In particular, the shorter wavelength of the laser pulse can evidently intensify the amplitude of the magnetic field. These enhancement and redistribution of the magnetic field are considered physically as a result of the competition of the electrostatic field (electron-ion separation) associated with the plasma wave, the atomic polarization field, and the pondoromotive potential associated with the laser field. This competition leads to the generation of a positive, large amplitude magnetic field in the zone of the pulse center, which forms a significant difference in partially and fully stripped plasmas. The numerical result shows further that the magnetic field is resonantly modulated by the plasma wave when the pulse length is the integer times the plasma wavelength. This apparently implies that the further enhancement and restructure of the large amplitude self-magnetic field can evidently impede the acceleration and stable transfer of the hot-electron beam

High-Current Cold Cathode Employing Diamond and Related Materials

Energy Technology Data Exchange (ETDEWEB)

Hirshfield, Jay L. [Omega-P, Inc., New Haven, CT (United States)

2014-10-22

The essence of this project was for diamond films to be deposited on cold cathodes to improve their emission properties. Films with varying morphology, composition, and size of the crystals were deposited and the emission properties of the cathodes that utilize such films were studied. The prototype cathodes fabricated by the methods developed during Phase I were tested and evaluated in an actual high-power RF device during Phase II. These high-power tests used the novel active RF pulse compression system and the X-band magnicon test facility at US Naval Research Laboratory. In earlier tests, plasma switches were employed, while tests under this project utilized electron-beam switching. The intense electron beams required in the switches were supplied from cold cathodes embodying diamond films with varying morphology, including uncoated molybdenum cathodes in the preliminary tests. Tests with uncoated molybdenum cathodes produced compressed X-band RF pulses with a peak power of 91 MW, and a maximum power gain of 16.5:1. Tests were also carried out with switches employing diamond coated cathodes. The pulse compressor was based on use of switches employing electron beam triggering to effect mode conversion. In experimental tests, the compressor produced 165 MW in a ~ 20 ns pulse at ~18× power gain and ~ 140 MW at ~ 16× power gain in a 16 ns pulse with a ~ 7 ns flat-top. In these tests, molybdenum blade cathodes with thin diamond coatings demonstrated good reproducible emission uniformity with a 100 kV, 100 ns high voltage pulse. The new compressor does not have the limitations of earlier types of active pulse compressors and can operate at significantly higher electric fields without breakdown.

Parallel superconducting strip-line detectors: reset behaviour in the single-strip switch regime

International Nuclear Information System (INIS)

Casaburi, A; Heath, R M; Tanner, M G; Hadfield, R H; Cristiano, R; Ejrnaes, M; Nappi, C

2014-01-01

Superconducting strip-line detectors (SSLDs) are an important emerging technology for the detection of single molecules in time-of-flight mass spectrometry (TOF-MS). We present an experimental investigation of a SSLD laid out in a parallel configuration, designed to address selected single strip-lines operating in the single-strip switch regime. Fast laser pulses were tightly focused onto the device, allowing controllable nucleation of a resistive region at a specific location and study of the subsequent device response dynamics. We observed that in this regime, although the strip-line returns to the superconducting state after triggering, no effective recovery of the bias current occurs, in qualitative agreement with a phenomenological circuit simulation that we performed. Moreover, from theoretical considerations and by looking at the experimental pulse amplitude distribution histogram, we have the first confirmation of the fact that the phenomenological London model governs the current redistribution in these large area devices also after detection events. (paper)

Trace analysis of Cd, Cu, Pb and Zn in various materials using differential pulse anodic stripping voltammetry

International Nuclear Information System (INIS)

Ahmed, R.; Viqar-un-Nisa; Tanwir, R.

1988-09-01

Sampling and sample preparation methods have been described. Digestion methods for different types of materials and acid purification systems have been developed. For trace analysis purposes cleaning methods for glassware etc. have been described. Differential pulse anodic stripping voltametric (DPASV) method has been worked out for the trace analysis of zn, cd, pb and Cu in different types of materials. Linearity of the method has been checked by drawing concentration versus currents (peak height) curves. Precision of the method has been checked by analysing a number of actual samples. of the method has been verified by analysing standards of U.S.A. Comparative studies have been done between Differential pulse anodic stripping voltammetric method and Atomic Absorption spectroscopic method. Problems of contamination and systematic errors during trace and ultra-trace analysis have been discussed. A variety of samples including soil, spinach, wheat flour, rice flour, dry milk, coriander, kidney stones, bladder stones etc. have been analysed and preliminary results have been reported. (author)

Pulsed electron beam generation with fast repetitive double pulse system

Energy Technology Data Exchange (ETDEWEB)

Sharma, Surender Kumar; Deb, Pankaj; Shyam, Anurag, E-mail: surender80@gmail.com [Energetics and Electromagnetics Division, Bhabha Atomic Research Centre, Visakhapatnam (India); Sharma, Archana [Accelerator and Pulse Power Division, Bhabha Atomic Research Centre, Mumbai (India)

2014-07-01

Longer duration high voltage pulse (∼ 100 kV, 260 ns) is generated and reported using helical pulse forming line in compact geometry. The transmission line characteristics of the helical pulse forming line are also used to develop fast repetition double pulse system with very short inter pulse interval. It overcomes the limitations caused due to circuit parameters, power supplies and load characteristics for fast repetitive high voltage pulse generation. The high voltage double pulse of 100 kV, 100 ns with an inter pulse repetition interval of 30 ns is applied across the vacuum field emission diode for pulsed electron beam generation. The electron beam is generated from cathode material by application of negative high voltage (> 100 kV) across the diode by explosive electron emission process. The vacuum field emission diode is made of 40 mm diameter graphite cathode and SS mesh anode. The anode cathode gap was 6 mm and the drift tube diameter was 10 cm. The initial experimental results of pulsed electron beam generation with fast repetitive double pulse system are reported and discussed. (author)

Study of position resolution for cathode readout MWPC with measurement of induced charge distribution

International Nuclear Information System (INIS)

Chiba, J.; Iwasaki, H.; Kageyama, T.; Kuribayashi, S.; Nakamura, K.; Sumiyoshi, T.; Takeda, T.

1983-01-01

A readout technqiue of multiwire proportional chambers by measurement of charges induced on cathode strips, orthogonal to anode wires, requires an algorithm to relate the measured charge distribution to the avalanche position. With given chamber parameters and under the influence of noise, resolution limits depend on the chosen algorithm. We have studied the position resolution obtained by the centroid method and by the charge-ratio method, both using three consecutive cathode strips. While the centroid method uses a single number, the center of gravity of the measured charges, the charge-ratio method uses the ratios of the charges Qsub(i-1)/Qsub(i) and Qsub(i+1)/Qsub(i) where Qsub(i) is the largest. To obtain a given resolution, the charge-ratio method generally allows wider cathode strips and therefore a smaller number of readout channels than the centroid method. (orig.)

Study of the hollow cathode plasma electron-gun

International Nuclear Information System (INIS)

Zhang Yonghui; Jiang Jinsheng; Chang Anbi

2003-01-01

For developing a novel high-current, long pulse width electron source, the theoretics and mechanism of the hollow cathode plasma electron-gun are analyzed in detail in this paper, the structure and the physical process of hollow cathode plasma electron-gun are also studied. This gun overcomes the limitations of most high-power microwave tubes, which employ either thermionic cathodes that produce low current-density beams because of the limitation of the space charge, or field-emission cathodes that offer high current density but provide only short pulse width because of plasma closure of the accelerating gap. In the theories studying on hollow cathode plasma electron-gun, the characteristic of the hollow-cathode discharge is introduced, the action during the forming of plasma of the stimulating electrode and the modulating anode are discussed, the movement of electrons and ions and the primary parameters are analyzed, and the formulas of the electric field, beam current density and the stabilization conditions of the beam current are also presented in this paper. The numerical simulation is carried out based on Poisson's equation, and the equations of current continuity and movement. And the optimized result is reported. On this basis, we have designed a hollow-cathode-plasma electron-gun, whose output pulse current is 2 kA, and pulse width is 1 microsecond

Direct fabrication of gas diffusion cathode by pulse electrodeposition for proton exchange membrane water electrolysis

Science.gov (United States)

Park, Hyanjoo; Choe, Seunghoe; Kim, Hoyoung; Kim, Dong-Kwon; Cho, GeonHee; Park, YoonSu; Jang, Jong Hyun; Ha, Don-Hyung; Ahn, Sang Hyun; Kim, Soo-Kil

2018-06-01

Pt catalysts for water electrolysis were prepared on carbon paper by using both direct current and pulse electrodeposition. Controlling the mass transfer of Pt precursor in the electrolyte by varying the deposition potential enables the formation of various Pt particle shapes such as flower-like and polyhedral particles. Further control of the deposition parameters for pulse electrodeposition resulted in changes to the particle size and density. In particular, the upper potential of pulse was found to be the critical parameter controlling the morphology of the particles and their catalytic activity. In addition to the typical electrochemical measurements, Pt samples deposited on carbon paper were used as cathodes for a proton exchange membrane water electrolyser. This single cell test revealed that our Pt particle samples have exceptional mass activity while being cost effective.

Population distribution of atomic uranium in the afterglow of a pulsed hollow-cathode discharge

International Nuclear Information System (INIS)

Demers, Yves; Gagne, J.-M.; Pianarosa, Piero

1987-01-01

From laser absorption measurements we have deduced the time evolution of the population distribution of atomic uranium in the afterglow of a pulsed hollow-cathode type discharge. The vapour generator operates with xenon as the discharge sustaining gas at a pressure of 280 Pa (2.1 Torr). The current pulse characteristics are width 250 μs and height 1.5 A. The pulse repetition frequency is 100 Hz. It is shown that the populations in the three metastable levels at 6249, 3868 and 3800 cm -1 decrease almost exponentially in a time interval between 150 and 300 μs. From 400 μs onwards in the afterglow, the atom population is essentially shared between the ground and the first metastable (620 cm -1 ) levels. Furthermore, starting from 9 ms in the afterglow more than 80% of the U atoms are found in the ground level. (author)

Differential pulse anodic stripping voltametry for ultratrace determination of cadmium and lead in Antarctic snow

International Nuclear Information System (INIS)

Scarponi, G.; Barbante, C.; Cescon, P.

1994-01-01

Differential pulse anodic stripping voltametry has sufficient sensitivity to be used for direct determination of heavy metals in Antarctic snow, thus avoiding long and contamination-prone enrichment procedures. A result of particular concern to global change studies can be drawn from these preliminary data: lead concentration in Antarctic snow decreased rapidly during the 1980s from about 10-15 pg/g to 2-4 pg/g in 1991. (authors). 16 refs., 3 figs., 1 tab

Sensitive Bioanalysis Based on in-Situ Droplet Anodic Stripping Voltammetric Detection of CdS Quantum Dots Label after Enhanced Cathodic Preconcentration

Directory of Open Access Journals (Sweden)

Xiaoli Qin

2016-08-01

Full Text Available We report a protocol of CdS-labeled sandwich-type amperometric bioanalysis with high sensitivity, on the basis of simultaneous chemical-dissolution/cathodic-enrichment of the CdS quantum dot biolabel and anodic stripping voltammetry (ASV detection of Cd directly on the bioelectrode. We added a microliter droplet of 0.1 M aqueous HNO3 to dissolve CdS on the bioelectrode and simultaneously achieved the potentiostatic cathodic preconcentration of Cd by starting the potentiostatic operation before HNO3 addition, which can largely increase the ASV signal. Our protocol was used for immunoanalysis and aptamer-based bioanalysis of several proteins, giving limits of detection of 4.5 fg·mL−1 for human immunoglobulin G, 3.0 fg·mL−1 for human carcinoembryonic antigen (CEA, 4.9 fg·mL−1 for human α-fetoprotein (AFP, and 0.9 fM for thrombin, which are better than many reported results. The simultaneous and sensitive analysis of CEA and AFP at two screen-printed carbon electrodes was also conducted by our protocol.

Monitoring of labile copper and zinc in estuarine waters using cathodic stripping chronopotentiometry

International Nuclear Information System (INIS)

Berg, C.M.G.

1991-01-01

Cathodic stripping chronopotentiometry (CSC) is readily suitable for automation, and sensitivity is often not affected by variations in major ion concentration (salinity) or by the dissolved concentration of oxygen. So this technique is very suitable for automated monitoring of certain trace elements in natural waters, including estuarine waters. The suitability of CSC for monitoring is demonstrated by measuring the concentrations of copper and zinc in the Tamar estuary in-line and automatically. The measuring rate was approximately 90h -1 . The concentrations of zinc and copper in the Tamar estuary were shown to behave in agreement with the findings of previous studies; the labile metal concentrations increased in the turbidity maximum and decreased immediately after it (at higher salinities) as a result of particle scavenging; gradual increase was apparent at intermediate salinities as result of pore-water injection, and the metal concentrations followed a dilution pattern with seawater at high salinities. In-line measurements provided a detailed picture of metal behaviour in this estuary and elucidated local inputs. The sensitivity (down to approximately 5 nM Cu and 6 nM Zn) allows monitoring of copper and zinc at levels common in estuarine and coastal waters, but is insufficient to monitor these metals in uncontaminated seawater. (author). 22 refs.; 4 figs

RF Electron Gun with Driven Plasma Cathode

CERN Document Server

Khodak, Igor

2005-01-01

It's known that RF guns with plasma cathodes based on solid-state dielectrics are able to generate an intense electron beam. In this paper we describe results of experimental investigation of the single cavity S-band RF gun with driven plasma cathode. The experimental sample of the cathode based on ferroelectric ceramics has been designed. Special design of the cathode permits to separate spatially processes of plasma development and electron acceleration. It has been obtained at RF gun output electron beam with particle energy ~500 keV, pulse current of 4 A and pulse duration of 80 ns. Results of experimental study of beam parameters are referred in. The gun is purposed to be applied as the intense electron beam source for electron linacs.

Cathode Readout with Stripped Resistive Drift Tubes

International Nuclear Information System (INIS)

Bychkov, V.N.; Kekelidze, G.D.; Novikov, E.A.; Peshekhonov, V.D.; Shafranov, M.D.; Zhil'tsov, V.E.

1994-01-01

A straw tube drift chamber prototype has been constructed and tested. The straw tube material is mylar film covered with carbon layer of resistivity 0.5, 30 and 70 k Ohm/sq. The gas mixture used was Ar/CH 4 . Both the anode wire and cathode signals were detected in order to study the behaviour of the chamber in the presence of X-ray ionization. The construction and the results of the study are presented. 7 refs., 11 figs., 1 tab

The construction and operating characteristics of a cathode strip chamber system designed to measure the reaction vertices of a stopping kaon beam

International Nuclear Information System (INIS)

M.W. Ahmed; D. Androic; I. Bertovic; J. Bjoraker; R. Chrien; X. Cui; D. Dehnhard; Anton Empl; M. Furic; J. Gerald; R. Gill; E.V. Hungerford; H. Jungst; K.J. Lan; Jinghua Liu; C.L. Morris; J.M. O'Donnell; J.C. Peng; T. Petkovic; P. Pile; M. Planinic; C.M. Riedel; A. Rusek; R. Sutter; Liguang Tang; H.A. Thiessen; M. Youn; V. Zeps

2001-01-01

The design, construction, and performance of a segmented-target, cathode-strip, tracking-detector is discussed. The chamber was made of low-Z materials in order to allow photons to leave the target region. It was used to determine the reaction vertex of stopping kaons, and was successfully operated in a high-intensity kaon beamline at the Alternating Gradient Synchrotron at Brookhaven National Laboratory. The vertical and horizontal resolutions of the stopping kaon reaction positions were sigma X∼ 0.454mm and sigma Y∼ 1.180mm, respectively. The uncertainty in the longitudinal (Z) direction is given by one-half the thickness of a target segment

The construction and operating characteristics of a cathode strip chamber system designed to measure the reaction vertices of a stopping kaon beam

International Nuclear Information System (INIS)

Ahmed, M.W.; Androic, D.; Bertovic, I.; Bjoraker, J.; Chrien, R.; Cui, X.; Dehnhard, D.; Empl, A.; Furic, M.; Gerald, J.; Gill, R.; Hungerford, E.V.; Juengst, H.; Lan, K.J.; Liu, J.H.; Morris, C.L.; O'Donnell, J.M.; Peng, J.C.; Petkovic, T.; Pile, P.; Planinic, M.; Riedel, C.M.; Rusek, A.; Sutter, R.; Tang, L.; Thiessen, H.A.; Youn, M.; Zeps, V.

2001-01-01

The design, construction, and performance of a segmented-target, cathode-strip, tracking-detector is discussed. The chamber was made of low-Z materials in order to allow photons to leave the target region. It was used to determine the reaction vertex of stopping kaons, and was successfully operated in a high-intensity kaon beamline at the Alternating Gradient Synchrotron at Brookhaven National Laboratory. The vertical and horizontal resolutions of the stopping kaon reaction positions were σ X ∼0.454 mm and σ Y ∼1.180 mm, respectively. The uncertainty in the longitudinal (Z) direction is given by one-half the thickness of a target segment

The construction and operating characteristics of a cathode strip chamber system designed to measure the reaction vertices of a stopping kaon beam

CERN Document Server

Ahmed, M W; Bertovic, I; Bjoraker, J; Chrien, R; Cui, X; Dehnhard, D; Empl, A; Furic, M; Gerald, J; Gill, R; Hungerford, E V; Juengst, H; Lan, K J; Liu, J H; Morris, C L; O'donnell, J M; Peng, J C; Petkovic, T; Pile, P; Planinic, M; Riedel, C M; Rusek, A; Sutter, R; Tang, L; Thiessen, H A; Youn, M; Zeps, V

2001-01-01

The design, construction, and performance of a segmented-target, cathode-strip, tracking-detector is discussed. The chamber was made of low-Z materials in order to allow photons to leave the target region. It was used to determine the reaction vertex of stopping kaons, and was successfully operated in a high-intensity kaon beamline at the Alternating Gradient Synchrotron at Brookhaven National Laboratory. The vertical and horizontal resolutions of the stopping kaon reaction positions were sigma sub X approx 0.454 mm and sigma sub Y approx 1.180 mm, respectively. The uncertainty in the longitudinal (Z) direction is given by one-half the thickness of a target segment.

Direct determination of tellurium and its redox speciation at the low nanogram level in natural waters by catalytic cathodic stripping voltammetry.

Science.gov (United States)

Biver, Marc; Quentel, François; Filella, Montserrat

2015-11-01

Tellurium is one of the elements recently identified as technologically critical and is becoming a new emergent contaminant. No reliable method exists for its determination in environmental samples such as natural waters. This gap is filled by the method described here; it allows the rapid detection of trace concentrations of Te(IV) and Te(VI) in surface waters by differential pulse cathodic stripping voltammetry. It is based on the proton reduction catalysed by the absorption of Te(IV) on the mercury electrode. Under our conditions (0.1 mol L(-1) HCl) a detection limit of about 5 ng L(-1) for a deposition time of 300 s is achieved. Organic matter does not represent a problem at low concentrations; higher concentrations are eliminated by adsorptive purification. Tellurium occurs primarily as Te(IV) and Te(VI) in natural waters. Thus, determining total Te requires the reduction of Te(VI) that it is not electroactive. A number of reduction procedures have been carefully evaluated and a method based on the addition of TiCl3 to the acidified samples has been proven to reduce Te(VI) at the trace level to Te(IV) reliably and quantitatively. Therefore, the procedure described allows the direct determination of total Te and its redox speciation. It is flexible, reliable and cost effective compared to any possible alternative method based on the common preconcentration-ICPMS approach. It is readily implementable as a routine method and can be deployed in the field with relative ease. Copyright © 2015 Elsevier B.V. All rights reserved.

A compact high-voltage pulse generator based on pulse transformer with closed magnetic core.

Science.gov (United States)

Zhang, Yu; Liu, Jinliang; Cheng, Xinbing; Bai, Guoqiang; Zhang, Hongbo; Feng, Jiahuai; Liang, Bo

2010-03-01

A compact high-voltage nanosecond pulse generator, based on a pulse transformer with a closed magnetic core, is presented in this paper. The pulse generator consists of a miniaturized pulse transformer, a curled parallel strip pulse forming line (PFL), a spark gap, and a matched load. The innovative design is characterized by the compact structure of the transformer and the curled strip PFL. A new structure of transformer windings was designed to keep good insulation and decrease distributed capacitance between turns of windings. A three-copper-strip structure was adopted to avoid asymmetric coupling of the curled strip PFL. When the 31 microF primary capacitor is charged to 2 kV, the pulse transformer can charge the PFL to 165 kV, and the 3.5 ohm matched load can deliver a high-voltage pulse with a duration of 9 ns, amplitude of 84 kV, and rise time of 5.1 ns. When the load is changed to 50 ohms, the output peak voltage of the generator can be 165 kV, the full width at half maximum is 68 ns, and the rise time is 6.5 ns.

Large area dispenser cathode applied to high current linac

International Nuclear Information System (INIS)

Yang Anmin; China Academy of Engineering Physics, Mianyang; Wu Dengxue; Liu Chenjun; Xia Liansheng; Wang Wendou; Zhang Kaizhi

2005-01-01

The paper introduced a dispenser cathode (411 M) which was 55 mm in diameter. A 200 kV long pulsed power generator with 2 μs flattop based on Marx-PEN and system with heat and voltage insulation were built. A 52 A space charge limited current was gained, when the temperature was 1165 degree C and the filament current was 18 A on the cathode and the voltage of the pulse was 75 kV at the cathode test stand. Experimental results show that the current values are consistent with the numerical simulation. The experiment reveals that the deflated gas will influence the cathode emission ability. (authors)

Differential Pulse Anodic Stripping Voltammetry for Mercury Determination

Directory of Open Access Journals (Sweden)

Vereștiuc Paul C.

2015-07-01

Full Text Available In the present work voltammetric investigations have been performed on HgCl2 aqueous solutions prepared from a Cz 9024 reagent. Carbon paste electrode (CPE, eriochrome black T modified carbon paste electrode (MCPE/EBT and KCl 1M as background electrolyte, were involved within the experimental procedures. Cyclic voltammetry (CV has been performed in order to compare the behaviour of the two electrodes in both K3[Fe(CN6] and mercury calibration aqueous solution. Differential pulse anodic stripping voltammetry (DPASV was used to determine the most suitable parameters for mercury determination. All experiments were performed at 25 ± 1 ℃, using an electrochemical cell with three-electrodes connected to an Autolab PG STAT 302N (Metrohm-Autolab potentiostat that is equipped with Nova 1.11 software. The measured potential values were generated by using the silver chloride electrode (AgClE as reference and a platinum wire electrode as auxiliary. A series of time depending equations for the pre-concentration and concentration steps were established, with the observation that a higher sensitivity can be obtained while increasing the pre-concentration time. DPASV were drawn using the CPE in 11.16 % coriander, as mercury complex, the voltamograms signals indicating mercury oxidation, with signal intensity increasing in time.

Zinc (Zn Analysis in Milk by Microwave Oven Digestion and Differential Pulse Anodic Stripping Voltametry (DPASV Technique

Directory of Open Access Journals (Sweden)

Mohineesh

2013-04-01

Full Text Available Milk is very important component of human diet. The presence of over limit of heavy metal in milk may create significant health problems. In the present study, the direct determination of Zinc (Zn heavy metal in milk samples of different brands was carried out by differential pulse anodic stripping Voltammetric technique at Hanging Mercury Drop Electrode (HMDE. Milk samples were processed by microwave oven digestion using HP/VHP Vessels and TFM Liners and nitric acid (HNO3.Determination of Zn was made in acetate buffer (pH 4.6 with a sweep rate (scan rate of 59.5 mV/s and pulse amplitude 50mV by HMDE by standard addition method. The solution was stirred during pre-electrolysis at -1150mV (vs. Ag/AgCl for 90 seconds and the potential was scanned from -1150V to +100V (vs. Ag/AgCl. The zinc ions were deposited by reduction at -1150 mV on HMDE. The stripping current arising from the oxidation of metal was correlated with the concentration the metal in the sample. .As a result the minimum level of Zn observed in the milk sample of different brands was determined as 2.28 mgL−1.

Electrochemical Performances of Diamond Like Carbon Films for Pb(II) Detection in Tap Water Using Differential Pulse Anodic Stripping Voltammetry Technique

Czech Academy of Sciences Publication Activity Database

Sbartai, A.; Namour, F.; Barbier, F.; Krejčí, J.; Kučerová, R.; Krejčí, T.; Neděla, Vilém; Sobota, Jaroslav; Jaffrezic-Renault, N.

2013-01-01

Roč. 11, č. 8 (2013), s. 1524-1529 ISSN 1546-198X Institutional support: RVO:68081731 Keywords : Diamond Like Carbon DLC * Lead Detection * Differential Pulse Anodic Stripping * Voltammetry * Tap Water Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 0.558, year: 2013

Particle-in-cell simulation of electron trajectories and irradiation uniformity in an annular cathode high current pulsed electron beam source

Energy Technology Data Exchange (ETDEWEB)

Jiang, Wei; Wang, Langping, E-mail: aplpwang@hit.edu.cn; Zhou, Guangxue; Wang, Xiaofeng

2017-02-01

Highlights: • The transmission process of electrons and irradiation uniformity was simulated. • Influence of the irradiation parameters on irradiation uniformity are discussed. • High irradiation uniformity can be obtained in a wide processing window. - Abstract: In order to study electron trajectories in an annular cathode high current pulsed electron beam (HCPEB) source based on carbon fiber bunches, the transmission process of electrons emitted from the annular cathode was simulated using a particle-in-cell model with Monte Carlo collisions (PIC-MCC). The simulation results show that the intense flow of the electrons emitted from the annular cathode are expanded during the transmission process, and the uniformity of the electron distribution is improved in the transportation process. The irradiation current decreases with the irradiation distance and the pressure, and increases with the negative voltage. In addition, when the irradiation distance and the cathode voltage are larger than 40 mm and −15 kV, respectively, a uniform irradiation current distribution along the circumference of the anode can be obtained. The simulation results show that good irradiation uniformity of circular components can be achieved by this annular cathode HCPEB source.

Development of extruded resistive plastic tubes for proportional chamber cathodes

International Nuclear Information System (INIS)

Kondo, K.

1982-01-01

Carbon mixed plastic tubes with resistivity of 10 3 approx. 10 4 Ωcm have been molded with an extrusion method and used for the d.c. cathode of a proportional counter and a multi-wire proportional chamber. The signal by gas multiplication was picked up from a strip r.f. cathode set outside the tube. The characteristics of the counter in the proportional and limited streamer modes have been studied

Hollow cathode for positive ion sources

International Nuclear Information System (INIS)

Schechter, D.E.; Kim, J.; Tsai, C.C.

1979-01-01

Development to incorporate hollow cathodes into high power ion sources for neutral beam injection systems is being pursued. Hollow tube LaB 6 -type cathodes, similar to a UCLA design, have been constructed and tested in several ORNL ion source configurations. Results of testing include arc discharge parameters of >1000 and 500 amps for 0.5 and 10 second pulse lengths, respectively. Details of cathode construction and additional performance results are discussed

A high precision straw tube chamber with cathode readout

International Nuclear Information System (INIS)

Bychkov, V.N.; Golutvin, I.A.; Ershov, Yu.V.; Zubarev, E.V.; Ivanov, A.B.; Lysiakov, V.N.; Makhankov, A.V.; Movchan, S.A.; Peshekhonov, V.D.; Preda, T.

1993-01-01

The high precision straw chamber with cathode readout was constructed and investigated. The 10 mm diameter straws were made of aluminized Mylar with transparent longitudinal window. The X-coordinate information has been taken from cathode strips as induced charges and investigated with the centroid method. The spatial resolution σ x =103 μm was obtained at a signal-to-noise ratio of about 70. The possible ways to improve the signal-to-noise ratio are discussed. (orig.)

Electron emission mechanism of carbon fiber cathode

International Nuclear Information System (INIS)

Liu Lie; Li Limin; Wen Jianchun; Wan Hong

2005-01-01

Models of electron emission mechanism are established concerning metal and carbon fiber cathodes. Correctness of the electron emission mechanism was proved according to micro-photos and electron scanning photos of cathodes respectively. The experimental results and analysis show that the surface flashover induces the electron emission of carbon fiber cathode and there are electron emission phenomena from the top of the carbon and also from its side surface. In addition, compared with the case of the stainless steel cathode, the plasma expansion velocity for the carbon fiber cathode is slower and the pulse duration of output microwave can be widened by using the carbon fiber cathode. (authors)

Knife-edge thin film field emission cathodes

International Nuclear Information System (INIS)

Lee, B.; Demroff, H.P.; Drew, M.M.; Elliott, T.S.; Mazumdar, T.K.; McIntyre, P.M.; Pang, Y.; Smith, D.D.; Trost, H.J.

1993-01-01

Cathodes made of thin-film field emission arrays (FEA) have the advantages of high current density, pulsed emission, and low bias voltage operation. The authors have developed a technology to fabricate knife-edge field emission cathodes on (110) silicon wafers. The emitter geometry is optimized for efficient modulation at high frequency. Cathode fabrication progress and preliminary analysis of their applications in RF power sources are presented

Virtual cathode regime in nonstationary electric high-current discharge in hydrogen

International Nuclear Information System (INIS)

Baksht, F.G.; Borodin, V.S.; Zhuravlev, V.N.

1988-01-01

Virtual cathode (VC) regime in a non-stationary high-current hydrogen arch is constructed. Basic calculational characteristics of the near-the-cathode layer are presented. The calculation was conducted for a 1 cm long cathode under 2x10 4 A/cm 2 current density in pulse and 10 atm. pressure. A rectangular current pulse was considered. It is shown that VC formation is caused by electron temperature reduction in the near-the-cathode area. This results in the reduction of ion flux from plasma to the cathode surface and finally in the change of a sign of space charge and field intensity near the surface. Under the transition to VC regime only the cathode temperature and its effective work function are practically changed, while the rest of parameters remain approximately constant

Development of plasma cathode electron guns

Science.gov (United States)

Oks, Efim M.; Schanin, Peter M.

1999-05-01

The status of experimental research and ongoing development of plasma cathode electron guns in recent years is reviewed, including some novel upgrades and applications to various technological fields. The attractiveness of this kind of e-gun is due to its capability of creating high current, broad or focused beams, both in pulsed and steady-state modes of operation. An important characteristic of the plasma cathode electron gun is the absence of a thermionic cathode, a feature which leads to long lifetime and reliable operation even in the presence of aggressive background gas media and at fore-vacuum gas pressure ranges such as achieved by mechanical pumps. Depending on the required beam parameters, different kinds of plasma discharge systems can be used in plasma cathode electron guns, such as vacuum arcs, constricted gaseous arcs, hollow cathode glows, and two kinds of discharges in crossed E×B fields: Penning and magnetron. At the present time, plasma cathode electron guns provide beams with transverse dimension from fractional millimeter up to about one meter, beam current from microamperes to kiloamperes, beam current density up to about 100 A/cm2, pulse duration from nanoseconds to dc, and electron energy from several keV to hundreds of keV. Applications include electron beam melting and welding, surface treatment, plasma chemistry, radiation technologies, laser pumping, microwave generation, and more.

Selection of high-brightness, laser-driven cathodes for electron accelerators and FELS

International Nuclear Information System (INIS)

Oettinger, P.E.

1987-01-01

Very intense, low emittance pulsed beams of electrons can be generated from laser-driven cathodes either by thermionic- or photo-emission. Several hundreds of amperes of electrons per square centimeter were observed for pulse lengths up to 50 ns. A normalized beam brightness of 10 7 A/cm 2 /rad 2 has been measured. These beams can be emission-gated at the cathode surface by modulating the laser-beam. Such beam bunching will generate picosecond-to-microsecond-long pulses at the source. A variety of cathodes are described, and a method of selection for specific applications is presented

Design and performance of the new cathode readout proportional chambers in LASS

International Nuclear Information System (INIS)

Aiken, G.; Aston, D.; Dunwoodie, W.

1980-10-01

The design and construction of a new proportional chamber system for the LASS spectrometer are discussed. This system consists of planar and cylindrical chambers employing anode wire and cathode strip readout techniques. The good timing characteristics of anode readout combine with the excellent spatial resolution of cathode readout to provide powerful and compact detectors. Preliminary resolution data are presented along with operating characteristics of the various devices

Mo-containing tetrahedral amorphous carbon deposited by dual filtered cathodic vacuum arc with selective pulsed bias voltage

International Nuclear Information System (INIS)

Pasaja, Nitisak; Sansongsiri, Sakon; Intarasiri, Saweat; Vilaithong, Thiraphat; Anders, Andre

2007-01-01

Metal-containing tetrahedral amorphous carbon films were produced by dual filtered cathodic vacuum arc plasma sources operated in sequentially pulsed mode. Negatively pulsed bias was applied to the substrate when carbon plasma was generated, whereas it was absent when the molybdenum plasma was presented. Film thickness was measured after deposition by profilometry. Glass slides with silver pads were used as substrates for the measurement of the sheet resistance. The microstructure and composition of the films were characterized by Raman spectroscopy and Rutherford backscattering, respectively. It was found that the electrical resistivity decreases with an increase of the Mo content, which can be ascribed to an increase of the sp 2 content and an increase of the sp 2 cluster size

Long-pulse applications of pulse-forming lines for high-power linac application

International Nuclear Information System (INIS)

Hoeberling, R.F.; Tallerico, P.J.

1981-01-01

The ever present demands for high efficiency in the RF power stations for particle accelerators have caused increased interest in longer RF pulses (ten's of microseconds) for linacs such as the Pion Generator for Medical Irradiation (PIGMI) and Free Electron Laser (FEL). For either RF power station, a fundamental decision is whether to use a modulating anode/hard-tube driver or pulsed cathode/line-type pulser configuration. The choices in the extremes of low power for very long pulses or for very-high-power, short pulses are, respectively, a modulated anode/hard tube modulator and pulsed cathode/pulse forming line. However, the demarcation between these two extremes is not clearcut. The criteria (cost, flexibility performance, reliability, efficiency) that resulted in the RF station definition of these two specific systems will be described

Electrode/Dielectric Strip For High-Energy-Density Capacitor

Science.gov (United States)

Yen, Shiao-Ping S.

1994-01-01

Improved unitary electrode/dielectric strip serves as winding in high-energy-density capacitor in pulsed power supply. Offers combination of qualities essential for high energy density: high permittivity of dielectric layers, thinness, and high resistance to breakdown of dielectric at high electric fields. Capacitors with strip material not impregnated with liquid.

The Graphene/l-Cysteine/Gold-Modified Electrode for the Differential Pulse Stripping Voltammetry Detection of Trace Levels of Cadmium

OpenAIRE

Yu Song; Chao Bian; Jianhua Tong; Yang Li; Shanghong Xia

2016-01-01

Cadmium(II) is a common water pollutant with high toxicity. It is of significant importance for detecting aqueous contaminants accurately, as these contaminants are harmful to human health and environment. This paper describes the fabrication, characterization, and application of an environment-friendly graphene (Gr)/l-cysteine/gold electrode to detect trace levels of cadmium (Cd) by differential pulse stripping voltammetry (DPSV). The influence of hydrogen overflow was decreased and the curr...

Enrichment and stripping voltametric behavior of technetium traces at a carbon paste electrode modified with TTA

International Nuclear Information System (INIS)

Dick, R.; Ruf, H.; Ache, H.J.

1988-06-01

The possibility of enrichment as well as the stripping voltammetric behavior of technetium traces at a carbon paste electrode modified with thenoyltrifluoroacetone (TTA) was studied. Accumulation of Tc(IV) on the electrode surface occurs without application of a deposition voltage due to complex formation with TTA, probably resulting Tc(TTA) 4 . During the following cathodic potential scan made with the differential pulse mode a characteristic current peak is obtained at -40 mV (vs. Ag/AgCl) which increases with Tc concentration and deposition time. However, Tc(IV) gives much more sensitive stripping current signals if a reductive deposition potential of -0.4 V is applied, presumably on account of the formation of Tc(TTA) 3 . In this case an anodic voltammetric scan was applied resulting a stripping peak at about +30 mV, the height of which is related to the concentration of Tc in solution as well as to the time of deposition. Calibration graphs revealed good reproducibility for analytical application. The lower detection limit for Tc(IV) achieved for 1 M sodium chloride solutions 4.6 x 10 -9 M. Tc(VII) is not enriched in the absence of reduction which takes place only from about -0.6 V on with the pH optimally set at 3.5. Therefore it is basically possible to discriminate Tc(IV) from Tc(VII). (orig.) [de

Influence of pulsed substrate bias on the structure and properties of Ti-Al-N films deposited by cathodic vacuum arc

Energy Technology Data Exchange (ETDEWEB)

Zhang, G.P., E-mail: princeterry@163.com [Institute of Physics, Chinese Academy of Science, Beijing 100080 (China); Gao, G.J. [Changchun University of Science and Technology, College of Science, Changchun 130000 (China); Wang, X.Q.; Lv, G.H.; Zhou, L.; Chen, H.; Pang, H.; Yang, S.Z. [Institute of Physics, Chinese Academy of Science, Beijing 100080 (China)

2012-07-15

Ti-Al-N films were deposited by cathodic vacuum arc (CVA) technique in N{sub 2} atmosphere with different pulsed substrate bias. The influence of pulsed substrate bias (0 to -800 V) on the deposition rate, surface morphology, crystal structure, and mechanical properties of the Ti-Al-N films were systematically investigated. Increasing pulsed bias voltage resulted in the decrease of deposition rate but the increase of surface roughness. It was found that there was a strong correlation between the pulsed bias and film structure. All the films studied in this paper were composed of TiN, AlN, and Ti-Al-N ternary phases. The grains changed from equiaxial to columnar and exhibited preferred orientation when the pulsed bias increased. With the increase of pulsed bias voltage, the atomic ratio of Ti to Al element increased gradually, while the N to (Ti + Al) ratio decreased. The composite films present an enhanced nanohardness compared with binary TiN and ZrN films. The film deposited with pulsed bias of -200 V possessed the maximum scratch critical load and nanohardness. The minimum friction coefficient with pulsed bias of -300 V was obtained.

Generation of uniform low-temperature plasma in a pulsed non-self-sustained glow discharge with a large-area hollow cathode

Energy Technology Data Exchange (ETDEWEB)

Akhmadeev, Yu. H.; Denisov, V. V., E-mail: volodyadenisov@yandex.ru; Koval, N. N.; Kovalsky, S. S.; Lopatin, I. V.; Schanin, P. M.; Yakovlev, V. V. [Russian Academy of Sciences, Institute of High-Current Electronics, Siberian Branch (Russian Federation)

2017-01-15

Generation of plasma in a pulsed non-self-sustained glow discharge with a hollow cathode with an area of ≥2 m{sup 2} at gas pressures of 0.4–1 Pa was studied experimentally. At an auxiliary arc-discharge current of 100 A and a main discharge voltage of 240 V, a pulse-periodic glow discharge with a current amplitude of 370 A, pulse duration of 340 μs, and repetition rate of 1 kHz was obtained. The possibility of creating a uniform gas-discharge plasma with a density of up to 10{sup 12} cm{sup −3} and an electron temperature of 1 eV in a volume of >0.2 m{sup 3} was demonstrated. Such plasma can be efficiently used to treat material surfaces and generate pulsed ion beams with a current density of up to 15 mA/cm{sup 2}.

Ram Pressure Stripping Made Easy: An Analytical Approach

Science.gov (United States)

Köppen, J.; Jáchym, P.; Taylor, R.; Palouš, J.

2018-06-01

The removal of gas by ram pressure stripping of galaxies is treated by a purely kinematic description. The solution has two asymptotic limits: if the duration of the ram pressure pulse exceeds the period of vertical oscillations perpendicular to the galactic plane, the commonly used quasi-static criterion of Gunn & Gott is obtained which uses the maximum ram pressure that the galaxy has experienced along its orbit. For shorter pulses the outcome depends on the time-integrated ram pressure. This parameter pair fully describes the gas mass fraction that is stripped from a given galaxy. This approach closely reproduces results from SPH simulations. We show that typical galaxies follow a very tight relation in this parameter space corresponding to a pressure pulse length of about 300 Myr. Thus, the Gunn & Gott criterion provides a good description for galaxies in larger clusters. Applying the analytic description to a sample of 232 Virgo galaxies from the GoldMine database, we show that the ICM provides indeed the ram pressures needed to explain the deficiencies. We also can distinguish current and past strippers, including objects whose stripping state was unknown.

A simple pulse shape discrimination technique applied to a silicon strip detector

International Nuclear Information System (INIS)

Figuera, P.; Lu, J.; Amorini, F.; Cardella, G.; DiPietro, A.; Papa, M.; Musumarra, A.; Pappalardo, G.; Rizzo, F.; Tudisco, S.

2001-01-01

Full text: Since the early sixties, it has been known that the shape of signals from solid state detectors can be used for particle identification. Recently, this idea has been revised in a group of papers where it has been shown that the shape of current signals from solid state detectors is mainly governed by the combination of plasma erosion time and charge carrier collection time effects. We will present the results of a systematic study on a pulse shape identification method which, contrary to the techniques proposed, is based on the use of the same electronic chain normally used in the conventional time of flight technique. The method is based on the use of charge preamplifiers, low polarization voltages (i.e. just above full depletion ones), rear side injection of the incident particles, and on a proper setting of the constant fraction discriminators which enhances the dependence of the timing output on the rise time of the input signals (which depends on the charge and energy of the incident ions). The method has been applied to an annular Si strip detector with an inner radius of about 16 mm and an outer radius of about 88 mm. The detector, manufactured by Eurisys Measures (Type Ips.73.74.300.N9), is 300 microns thick and consists of 8 independent sectors each divided into 9 circular strips. On beam tests have been performed at the cyclotron of the Laboratori Nazionali del Sud in Catania using a 25.7 MeV/nucleon 58 Ni beam impinging on a 51 V and 45 Sc composite target. Excellent charge identification from H up to the Ni projectile has been observed and typical charge identification thresholds are: ∼ 1.7 MeV/nucleon for Z ≅ 6, ∼ 3.0 MeV/nucleon for Z ≅ 11, and ∼ 5.5 MeV/nucleon for Z ≅ 20. Isotope identification up to A ≅ 13 has been observed with an energy threshold of about 6 MeV/nucleon. The identification quality has been studied as a function of the constant fraction settings. The method has been applied to all the 72 independent strips

Cathode plasma expansion in diode with explosive emission

International Nuclear Information System (INIS)

Zuo Yinghong; Fan Ruyu; Wang Jianguo; Zhu Jinhui

2012-01-01

The evolution characteristics of the cathode plasma in a planar diode with explosive emission were analyzed. Be- sides the axial expansion which can reduce the effective anode-cathode gap, the radial expansion of the cathode plasma which can affect the effective emitting area was also taken into account. According to the Child-Langmuir law and the experimental data of current and voltage with a electron vacuum diode under four-pulse mode, the dynamics of the cathode plasma was investigated, on the assumption that the radial speeds of the cathode plasma was approximately equal to the axial speed. The results show that the radial and axial expansion speeds of the cathode plasma are 0.9-2.8 cm/μs. (authors)

Anode and cathode geometry and shielding gas interdependence in GTAW

International Nuclear Information System (INIS)

Key, J.F.

1979-01-01

Parametric analyses and high-speed photography of the interdependence of electrode (cathode) tip geometry, shielding gas composition, and groove (anode) geometry indicate that spot-on-plate tests show that blunt cathode shapes have penetration effects similar to addition of a high ionization potential inert gas (such as helium) to the argon shielding gas. Electrode shape and shielding gas composition effects are not synergistic. The time required to develop a given penetration is a function of anode and cathode geometry and shielding gas composition, in addition to other essential welding variables. Spot-on-plate tests are a valid analysis of radical pulsed GTAW. Bead-on-plate tests are a valid analysis of mild pulsed or constant current GTAW

Multi-kiloampere, electron-beam generation from bare aluminum photo-cathodes driven by an ArF laser

International Nuclear Information System (INIS)

Carlson, R.L.; Ridlon, R.N.; Seitz, G.J.; Hughes, T.P.

1997-01-01

An electron-beam-pumped laser operating at ArF (193 nm) producing up to 5.0 joules in a 150-ns pulse has been used to illuminate micro-machined aluminum cathodes. The cathode was pulsed from 2.25- up to 2.95-MV across a 20-cm-AK gap producing fields up to 145 kV/cm using REX (a 4-MeV, 5-kA, 100-ns pulsed diode). Extracted current versus laser power gives a quantum efficiency increasing with power density from 0.07 to 0.11%. The present work is significant in that the cathode operates in the presence of out-gassing materials with a background vacuum pressure in the mid 10 -6 torr region and 100-ns-long electron beams of up to 3 kA have been produced. Both emission limited (current follows laser pulse) and space-charge-limited (current follows pulsed power) regimes have been studied up to ∼ 50 A/cm 2 by varying the cathode diameter. The beam temperature has been measured to be < 5 eV and directly compared in the same experimental setup to velvet based cathodes that measure ∼ 100 eV

High-power, high-brightness pseudospark-produced electron beam driven by improved pulse line accelerator

International Nuclear Information System (INIS)

Junbino Zhu; Mingchang Wang; Zhijiang Wang

1995-01-01

A high power (200KV), intense current density, low emittance (71mmmrad), high brightness (8x10 10 A/m rad) electron beam was generated in the 10cm long, high-voltage-resistive multi-gap hollow cathode pseudospark chamber filled with 15pa nitrogen and driven by an improved pulse line accelerator. The beam was ejected with the 1mm diameter, the 2.2KA beam current, and the 400ns pulse length, and could propagated 20cm in the drift tube. At a distance of 5cm from the anode it penetrated consecutively an acid-sensitive discoloring film and a 0.05mm-thick copper foil both stuck closely, left 0.6mm and 0.3mm holes on them, respectively. That 10 shots on an acid-sensitive film produced a hole of 1.6mm at 7cm downstream of anode showed its good repeatability. After 60 shots the pseudospark discharge chamber was disassembled and observed that almost no destructive damage traces left on the surfaces of its various electrodes and insulators. But on almost all the surfaces of changeable central hole parts installed on intermediate electrodes there are traces of electron emission from the sides facing the anode and of bombardment on the sides facing the cathode, in contrast with which on the front- and back-surfaces of hollow cathode no visible traces of electron emission from then was observed. In addition, there were different tints, strip-like regions on the side of anode facing the cathode. Another interesting phenomenon was that there were a set of concentric circular or elliptical ring pattern on the acid-sensitive discoloring film got at 5cm from the anode and observed tinder a metallograph. It seems that the pseudospark electron beam is Laminar beam i.e, being possessed of a multi-layer structure, at least in the case of multi-gap pseudospark discharge chamber. It was found experimentally that the quality of pseudospark electron beam is much better than that of the cold-cathode electron beam

Cs-K-Te photo cathodes: a promising electron source for free-electron lasers

NARCIS (Netherlands)

Bisero, D.; Bisero, D.; van Oerle, B.M.; van Oerle, B.M.; Ernst, G.J.; Verschuur, Jeroen W.J.; Witteman, W.J.

1998-01-01

The characteristics of Cs–K–Te photo-cathodes when used in a photo-cathode linear accelerator will be presented together with a short review of their photo-emissive properties. The cathodes have been illuminated by light pulses obtained by frequency quadrupling the light of a Nd:YLF laser. The

Studies on the optogalvanic effect and isotope-selective excitation of ytterbium in a hollow cathode discharge lamp using a pulsed dye laser.

Science.gov (United States)

Kumar, Pankaj; Kumar, Jitendra; Prakash, Om; Saini, Vinod K; Dixit, Sudhir K; Nakhe, Shankar V

2013-09-01

This paper presents studies on the pulsed optogalvanic effect and isotope-selective excitation of Yb 555.648 nm (0 cm(-1) → 17 992.007 cm(-1)) and 581.067 nm (17 992.007 cm(-1) → 35 196.98 cm(-1)) transitions, in a Yb/Ne hollow cathode lamp. The Yb atoms were excited by narrow linewidth (500-1000 MHz) Rh110 and Rh6G dye based pulsed lasers. Optogalvanic signal inversion for ground state transition at 555.648 nm was observed beyond a hollow cathode discharge current of 8.5 mA, in contrast to normal optogalvanic signal at 581.067 nm up to maximum current of 14 mA. The isotope-selective excitation studies of Yb were carried out by recording Doppler limited optogalvanic signals as a function of dye laser wavelength. For the 581.067 nm transition, three even isotopes, (172)Yb, (174)Yb, and (176)Yb, and one odd isotope, (171)Yb, were clearly resolved. These data were compared with selective isotope excitation by 10 MHz linewidth continuous-wave dye laser. For 555.648 nm transition, isotopes were not clearly resolved, although isotope peaks of low modulation were observed.

Cathodic stripping voltammetric determination of chromium in coastal waters on cubic Nano-titanium carbide loaded gold nanoparticles modified electrode

Directory of Open Access Journals (Sweden)

Haitao eHan

2015-09-01

Full Text Available The novel cubical nano-titanium carbide loaded gold nanoparticles modified electrode for selective and sensitive detection of trace chromium (Cr in coastal water was established based on a simple approach. Nano-titanium carbide is used as the typical cubical nanomaterial with wonderful catalytic activity towards the reduction of Cr(VI. Gold nanoparticles with excellent physical and chemical properties can facilitate electron transfer and enhance the catalytic activity of the modified electrode. Taking advantage of the synergistic effects of nano-titanium carbide and gold nanoparticles, the excellent cathodic signal responses for the stripping determination of Cr(VI can be obtained. The detection limit of this method is calculated as 2.08 μg L-1 with the linear calibration curve ranged from 5.2 to 1040 μg L-1. This analytical method can be used to detect Cr(VI effectively without using any complexing agent. The fabricated electrode was successfully applied for the detection of chromium in coastal waters collected from the estuary giving Cr concentrations between 12.48 and 22.88 μg L-1 with the recovery between 96% and 105%.

Electron emitter pulsed-type cylindrical IEC

International Nuclear Information System (INIS)

Miley, G.H.; Gu, Y.; Stubbers, R.; Zich, R.; Anderl, R.; Hartwell, J.

1997-01-01

A cylindrical version of the single grid Inertial Electrostatic Confinement (IEC) device (termed the C-device) has been developed for use as a 2.5-MeV D-D fusion neutron source for neutron activation analysis. The C-device employs a hollow-tube type cathode with similar anodes backed up by ''reflector'' dishes. The resulting discharge differs from a conventional hollow cathode discharge, by creating an explicit ion beam which is ''pinched'' in the cathode region. Resulting fusion reactions generate ∼10 6 neutron/s. A pulsed version is under development for applications requiring higher fluxes. Several pulsing techniques are under study, including an electron emitter (e-emitter) assisted discharge in a thorated tungsten wire emitter located behind a slotted area in the reflector dishes. Pulsing is initiated after establishing a low power steady-state discharge by pulsing the e-emitter current using a capacitor switch type circuit. The resulting electron jet, coupled with the discharge by the biased slot array, creates a strong pulse in the pinched ion beam. The pulse length/repetition rate are controlled by the e-emitter pulse circuit. Typical parameters in present studies are ∼30micros, 10Hz and 1-amp ion current. Corresponding neutron measurements are an In-foil type activation counter for time averaged rates. Results for a wide variety of operating conditions are presented

Plasma-induced evolution behavior of space-charge-limited current for multiple-needle cathodes

International Nuclear Information System (INIS)

Li Limin; Liu Lie; Zhang Jun; Wen Jianchun; Liu Yonggui; Wan Hong

2009-01-01

Properties of the plasma and beam flow produced by tufted carbon fiber cathodes in a diode powered by a ∼500 kV, ∼400 ns pulse are investigated. Under electric fields of 230-260 kV cm -1 , the electron current density was in the range 210-280 A cm -2 , and particularly at the diode gap of 20 mm, a maximum beam power density of about 120 MW cm -2 was obtained. It was found that space-charge-limited current exhibited an evolution behavior as the accelerating pulse proceeded. There exists a direct relation between the movement of plasma within the diode and the evolution of space-charge-limited current. Initially in the accelerating pulse, the application of strong electric fields caused the emission sites to explode, forming cathode flares or plasma spots, and in this stage the space-charge-limited current was approximately described by a multiple-needle cathode model. As the pulse proceeded, these plasma spots merged and expanded towards the anode, thus increasing the emission area and shortening the diode gap, and the corresponding space-charge-limited current followed a planar cathode model. Finally, the space-charge-limited current is developed from a unipolar flow into a bipolar flow as a result of the appearance of anode plasma. In spite of the nonuniform distribution of cathode plasma, the cross-sectional uniformity of the extracted electron beam is satisfactory. The plasma expansion within the diode is found to be a major factor in the diode perveance growth and instability. These results show that these types of cathodes can offer promising applications for high-power microwave tubes.

Development of floating strip micromegas detectors

Energy Technology Data Exchange (ETDEWEB)

Bortfeldt, Jonathan

2014-04-28

Micromegas are high-rate capable, high-resolution micro-pattern gaseous detectors. Square meter sized resistive strip Micromegas are foreseen as replacement of the currently used precision tracking detectors in the Small Wheel, which is part of the forward region of the ATLAS muon spectrometer. The replacement is necessary to ensure tracking and triggering performance of the muon spectrometer after the luminosity increase of the Large Hadron Collider beyond its design value of 10{sup 34} cm{sup -2}s{sup -1} around 2020. In this thesis a novel discharge tolerant floating strip Micromegas detector is presented and described. By individually powering copper anode strips, the effects of a discharge are confined to a small region of the detector. This reduces the impact of discharges on the efficiency by three orders of magnitude, compared to a standard Micromegas. The physics of the detector is studied and discussed in detail. Several detectors are developed: A 6.4 x 6.4 cm{sup 2} floating strip Micromegas with exchangeable SMD capacitors and resistors allows for an optimization of the floating strip principle. The discharge behavior is investigated on this device in depth. The microscopic structure of discharges is quantitatively explained by a detailed detector simulation. A 48 x 50 cm{sup 2} floating strip Micromegas is studied in high energy pion beams. Its homogeneity with respect to pulse height, efficiency and spatial resolution is investigated. The good performance in high-rate background environments is demonstrated in cosmic muon tracking measurements with a 6.4 x 6.4 cm{sup 2} floating strip Micromegas under lateral irradiation with 550 kHz 20 MeV proton beams. A floating strip Micromegas doublet with low material budget is developed for ion tracking without limitations from multiple scattering in imaging applications during medical ion therapy. Highly efficient tracking of 20 MeV protons at particle rates of 550 kHz is possible. The reconstruction of the

Development of floating strip micromegas detectors

International Nuclear Information System (INIS)

Bortfeldt, Jonathan

2014-01-01

Micromegas are high-rate capable, high-resolution micro-pattern gaseous detectors. Square meter sized resistive strip Micromegas are foreseen as replacement of the currently used precision tracking detectors in the Small Wheel, which is part of the forward region of the ATLAS muon spectrometer. The replacement is necessary to ensure tracking and triggering performance of the muon spectrometer after the luminosity increase of the Large Hadron Collider beyond its design value of 10 34 cm -2 s -1 around 2020. In this thesis a novel discharge tolerant floating strip Micromegas detector is presented and described. By individually powering copper anode strips, the effects of a discharge are confined to a small region of the detector. This reduces the impact of discharges on the efficiency by three orders of magnitude, compared to a standard Micromegas. The physics of the detector is studied and discussed in detail. Several detectors are developed: A 6.4 x 6.4 cm 2 floating strip Micromegas with exchangeable SMD capacitors and resistors allows for an optimization of the floating strip principle. The discharge behavior is investigated on this device in depth. The microscopic structure of discharges is quantitatively explained by a detailed detector simulation. A 48 x 50 cm 2 floating strip Micromegas is studied in high energy pion beams. Its homogeneity with respect to pulse height, efficiency and spatial resolution is investigated. The good performance in high-rate background environments is demonstrated in cosmic muon tracking measurements with a 6.4 x 6.4 cm 2 floating strip Micromegas under lateral irradiation with 550 kHz 20 MeV proton beams. A floating strip Micromegas doublet with low material budget is developed for ion tracking without limitations from multiple scattering in imaging applications during medical ion therapy. Highly efficient tracking of 20 MeV protons at particle rates of 550 kHz is possible. The reconstruction of the track inclination in a single

Laser-pulsed relativistic electron gun

International Nuclear Information System (INIS)

Sherman, N.K.

1986-01-01

A relativistic (β ≅ 0.8) electron gun with good emittance and subnanosecond pulse duration which can be synchronized to picosecond laser pulses is being developed at NRC for use in studies of particle acceleration by lasers. Bursts of electron pulses exceeding 280 keV in energy have been extracted into air form a laser-driven vacuum photodiode. Trains of 5 ps pulses of ultraviolet UV light illuminate a magnesium cathode. Photoelectrons emitted from the cathode are accelerated in a graded electrostatic potential set up by a 360 kV Marx-generator. The UV pulses are obtained by doubling the frequency of a 606 nm dye laser modelocked at 160 MHz. Electron energies were measured by residual range in an echelon of Al foils. Total charge per burst was measured by picoammeter. Time structure of the bursts has been examined with plastic scintillator and a fast photomultiplier. Tests on a low voltage photodiode achieved a current density of 180 A/cm/sup 2/ from an Mg cathode, with quantum efficiency of 2.4 x 10/sup -6/ electron per UV photon. The brevity and intensity of the laser pulses cause the electric charge collected per pulse to increase linearly with bias voltage rather than according to the Langmuir-Child law. Gun emittance is about 150 mm-msr and beam brightness is about 1A/cm/sup 2/-sr. Estimated duration of individual electron pulses of a burst is about 400 ps with instantaneous current of about 0.1 mA. Energy spread within one pulse is expected to be about 15%. This gun has the potential to be a useful source of relativistic electrons for laser acceleration studies

Simultaneous detection of metronidazole and chloramphenicol by differential pulse stripping voltammetry using a silver nanoparticles/sulfonate functionalized graphene modified glassy carbon electrode

International Nuclear Information System (INIS)

Zhai, Haiyun; Liang, Zhixian; Chen, Zuanguang; Wang, Haihang; Liu, Zhenping; Su, Zihao; Zhou, Qing

2015-01-01

Graphical abstract: Display Omitted -- Highlights: • A novel and reliable AgNPs/SF-GR modified glassy carbon electrode was constructed and characterized. • The AgNPs/SF-GR/GCE was successfully applied in the shrimp for simultaneous determination of MTZ and CAP. • Under optimized conditions, common substances such as UA, AA, DA and ion did not interfered in the electrode performance. • The modified electrode exhibited considerable sensitivity, stability and reproducibility. • This fabricated electrode achieved a satisfactory level compared with other electrodes toward MTZ and CAP. -- Abstract: A novel silver nanoparticles/sulfonated functionalized graphene modified glassy carbon electrode (AgNPs/SF-GR/GCE) was fabricated to determine chloramphenicol and metronidazole simultaneously. Taking advantage of sulfonic group, AgNPs were successfully electrodeposited on functionalized GR immobilized on the surface of a GCE. Scanning electron microscopy and energy spectrum analysis results confirmed that AgNPs were deposited on the functionalized GR film. Compared to the bare GCE or the pristine SF-GR modified electrode, AgNPs/SF-GR/GCE exhibited excellent electroreduction towards chloramphenicol and metronidazole. In addition, the two antibacterial drugs were separated completely in 0.10 M citric acid-sodium citrate buffer (pH 4.0) by differential pulse stripping voltammetry under optimum conditions. The cathodic current was linearly related with 0.02∼20.0 μM chloramphenicol and 0.10∼20.0 μM metronidazole, with the detection limits of 0.01 μM and 0.05 μM respectively. Furthermore, AgNPs/SF-GR/GCE was applied to the simultaneous determination of chloramphenicol and metronidazole in an aquatic product

Position resolution of MSGCs with cathode readout

International Nuclear Information System (INIS)

Amos, N.; Cremaldi, L.; Finocchiaro, G.; Gobbi, B.; Ng, K.K.; Manzella, V.; Peskov, V.; Rajagopalan, S.; Rubinov, P.; Schamberger, D.; Sellberg, G.; Steffens, J.; Tilden, R.; Wang, P.; Yu, Y.

1997-01-01

The performance of a telescope of micro-strip gas chambers (MSGC) has been studied in a beam of pions. Detectors with different anode pitch and with different substrates have been operated using several gas mixtures. The position resolutions obtained by reading out the cathodes for the 200 μm pitch is 42 μm. For the 400 μm pitch detectors the resolution is 42 μm after correcting the centroid positions with a function derived from the data. (orig.)

Efficient electron beam deposition for repetitively pulsed krypton fluoride lasers

International Nuclear Information System (INIS)

Hegeler, F.; Myers, M.C.; Friedman, M.; Sethian, J.D.; Swanekamp, S.B.; Rose, D.V.; Welch, D.R.

2002-01-01

We have demonstrated that we can significantly increase the electron beam transmission efficiency through a pressure foil structure (hibachi) by segmenting the beam into strips to miss the hibachi support ribs. In order to increase the electron beam transmission, the cathode strips are adjusted to compensate for beam rotation and pinching. The beam propagation through the hibachi has been both measured and simulated with 1-D and 3-D codes

High performance electrode material for supercapacitors based on α-Co(OH)2 nano-sheets prepared through pulse current cathodic electro-deposition (PC-CED)

Science.gov (United States)

Aghazadeh, Mustafa; Rashidi, Amir; Ganjali, Mohammad Reza

2018-01-01

In this paper, the well-defined nano-sheets of α-Co(OH)2 were prepared through the cathodic electrosynthesis from an additive-free aqueous cobalt nitrate bath. The pulse current cathodic electro-deposition (PC-CED) was used as the means for the controlling the OH- electrogeneration on the cathode surface. The characteristics and electrochemical behavior of the prepared cobalt hydroxide were also assessed through SEM, TEM, XRD, BET, and IR. The results proved the product to be composed of crystalline pure α phase of cobalt hydroxide with sheet-like morphology at nanoscale. Evaluations of the electrochemical behaviour of the α-Co(OH)2 nano-sheets revealed that they are capable to delivering the specific capacitance of 1122 F g-1 at a discharge load of 3 A g-1 and SC retention of 84% after 4000 continues discharging cycles, suggesting the nano-sheets as promising candidates for use in electrochemical supercapacitors. Further, the method used for the preparation of the compounds enjoys the capability of being scaled up. [Figure not available: see fulltext.

Cathodic protection of steel by electrodeposited zinc-nickel alloy coatings

Energy Technology Data Exchange (ETDEWEB)

Baldwin, K.R.; Smith, C.J.E. [Defence Research Agency, Farnborough (United Kingdom). Structural Materials Centre; Robinson, M.J. [Cranfield Univ. (United Kingdom). School of Industrial and Manufacturing Science

1995-12-01

The ability of electrodeposited zinc-nickel alloy coatings to cathodically protect steel was studied in dilute chloride solutions. The potential distribution along steel strips partly electroplated with zinc-nickel alloys was determined, and the length of exposed steel that was held below the minimum protection potential (E{sub prot}) was taken as a measure of the level of cathodic protection (CP) provided by the alloy coatings. The level of CP afforded by zinc alloy coatings was found to decrease with increasing nickel content. When nickel content was increased to {approx} {ge} 21 wt%, no CP was obtained. Surface analysis of uncoupled zinc-nickel alloys that were immersed in sodium chloride (NaCl) solutions showed the concentration of zinc decreased in the surface layers while the concentration of nickel increased, indicating that the alloys were susceptible to dezincification. The analysis of zinc-nickel alloy coatings on partly electroplated steel strips that were immersed in chloride solution showed a significantly higher level of dezincification than that found for uncoupled alloy coatings. This effect accounted for the rapid loss of CP afforded to steel by some zinc alloy coatings, particularly those with high initial nickel levels.

Application of Box-Behnken designs in parameters optimization of differential pulse anodic stripping voltammetry for lead(II) determination in two electrolytes.

Science.gov (United States)

Yu, Xiao-Lan; He, Yong

2017-06-05

Box-Behnken design was advantageous to parameters optimization of differential pulse anodic stripping voltammetry (DPASV) for the analysis of lead(II) with its high efficiency and accuracy. Five Box-Behnken designs were designed and conducted in the electrolyte of 0.1 mol/L acetate buffer and 0.1 mol/L HCl without the removal of oxygen. Significant parameters and interactions in each electrolyte were found (P-value Box-Behnken designs in parameters optimization of DPASV for lead(II) determination regardless of the electrolyte kinds.

Characterization of diamond-like carbon coatings prepared by pulsed bias cathodic vacuum arc deposition

International Nuclear Information System (INIS)

Wu Jinbao; Chang, J.-J.; Li, M.-Y.; Leu, M.-S.; Li, A.-K.

2007-01-01

Hydrogen free diamond-like carbon (DLC) coatings have been deposited on Si(100) and stainless steel substrates by cathodic vacuum arc plasma deposition with pulse voltage. Adherent deposits on silicon can be obtained through applying gradient Ti/TiC/DLC layers. A pulse bias of - 100 V was applied to the substrate in order to obtain a denser structure of DLC coating approximately 1 μm thick. The microstructure and hardness value of DLC films were analyzed by using X-ray photoelectron spectroscopy and nano-indenter. The experimental results show that the duty cycle strongly influenced the hardness and sp 3 content of the DLC coatings. We observed that when the duty cycle was raised from 2.5% to 12.5%, the hardness increased from 26 GPa to 49 GPa, and the sp 3 fraction of the DLC films measured by XPS increased from 39% to 50.8 % as well. But at constant duty cycle, say 12.5%, the hardness is dropped from 49 to 14 GPa in proportion to the increase of residual gas pressure from 3 x 10 -3 Pa to 1 Pa. As the residual gas pressure increased, collisional phenomenon will decrease the energy of the ions. Ions with low energy make more graphitic carbon links and result in a low hardness value

Factors influencing the performances of micro-strips gas chambers

International Nuclear Information System (INIS)

Mack, V.; Brom, J.M.; Fang, R.; Fontaine, J.C.; Huss, D.; Kachelhoffer, T.; Kettunen, H.; Levy, J.M.; Pallares, A.; Bergdolt, A.M.; Cailleret, J.; Christophel, E.; Coffin, J.; Eberle, H.; Osswald, F.; Sigward, M.H.

1995-01-01

Damages to MSGCs (Micro-Strips Gas Chambers) induced by discharges have been investigated. Optimization of electrode shapes and/or deposition of a protective coating allows the potential difference between anode and cathode, thus increasing the gain. For prototypes of MSGCs made at the Centre de Recherches Nucleaires, each step of the manufacturing processes was carefully controlled. Results are presented on the influence of cleaning processes on the surface resistance of glass substrates. (author). 21 refs., 8 figs., 2 tabs

THz Wave Propagation on Strip Lines: Devices, Properties, and Applications

Directory of Open Access Journals (Sweden)

Y. Kadoya

2008-06-01

Full Text Available We report the propagation characteristics of THz pulses on micro-strip-lines and coplanar strip-lines, in which low permittivity polymer materials are used as the dielectric layer or the substrate. As a result of the low attenuation and small dispersion in the devices, the spectral width up to 3 THz can be achieved even after the 1 mm propagation. Spectroscopic characterizations of liquid or powder specimens are demonstrated using the devices. We also show a possibility of realizing a very low attenuation using a quadrupole mode in three strip coplanar lines on the polymer substrate.

Energy resolution in X-ray detecting micro-strip gas counters

CERN Document Server

Bateman, J E; Derbyshire, G E; Duxbury, D M; Mir, J A; Spill, E J; Stephenson, R

2002-01-01

Systematic measurements of the energy resolution available from a Micro-Strip Gas Counter (MSGC) are presented. The effect of factors such as bias potential, gas filling and strip geometry on the energy resolution are examined in detail and related to a simple model. The geometry of the MSGC is adapted to permit 'wall-less' detection of X-rays and this results in useful improvements in the pulse height spectra.

Studies on pulsed optogalvanic effect in Eu/Ne hollow cathode discharge.

Science.gov (United States)

Saini, V K; Kumar, P; Dixit, S K; Nakhe, S V

2014-07-01

The optogalvanic (OG) effect has been observed in a Eu/Ne hollow cathode discharge lamp using pulsed laser irradiation. An OG spectrum is recorded in dye laser wavelength region 574–602 nm using a boxcar-averager. In total 41 atomic lines are observed. Of these, 38 lines are assigned to neon transitions. Two lines observed corresponding to wavelengths 576.519 and 601.815 nm are assigned to europium transitions; (4f 7 6s 2 , S 8 7/2 →4f 7 6s6p , zP 6 7/2 ) and (4f 7 6s 2 , S 8 7/2 →4f 7 6s6p , zP 8 9/2 ), respectively, and the remaining line at 582.475 nm could not be assigned. The effect of the discharge current on europium as well as neon OG signals is also studied. At moderate discharge current values, an extra positive peak is observed in neon OG signal for the transition (1s 5 →2p 2 ) at 588.189 nm, which is explained by Penning-ionization process using the quasi-resonant energy transfer interactions between excited neon and europium atoms lying in 2p 2 and D 10 9/2 states, respectively.

Neutron measurements in deuterated palladium cathodes subjected to pulsed electrolytic currents

International Nuclear Information System (INIS)

Granada, J.R.; Mayer, R.E.; Guido, G.; Florido, P.C.; Patino, N.E.; Gillette, V.H.; Sobehart, L.; Gomez, S.; Larreteguy, A.; Universidad Nacional de Cuyo, San Carlos de Bariloche

1989-01-01

We report on neutron measurements performed on electrolytic cells using a high efficiency (22%) detection system in combination with a procedure involving a non-stationary current through the cell's circuit. Under these conditions, neutron production was observed in cells containing LiH dissolved in heavy water with a Palladium cathode. Characteristic patterns showing one or two bumps were obtained in a repeatable fashion, depending on the previous charging history of the cathode. (orig.)

Pulsed current generator

International Nuclear Information System (INIS)

Semenov, V.D.; Furman, Eh.G.

1974-01-01

The paper describes a current pulse generator with an auxiliary network consisting of a choke and diode in series designed to enlarge the range of pulse frequency control. One output of the network is connected to an adjustable valve cathode and via antoher auxiliary condenser to the point where the cathode of the main key unit is joined to the start of the magnetizing coil. A second output is connected to the anode of another adjustable valve and via another auxiliary condenser to the point where the anode of the other main key unit is joined to the end of the magnetizing coil. The generator can be used to excite the electromagnets of charged particle accelerators or in devices designed to produce magnetic fields. (author)

High-voltage isolation transformer for sub-nanosecond rise time pulses constructed with annular parallel-strip transmission lines.

Science.gov (United States)

Homma, Akira

2011-07-01

A novel annular parallel-strip transmission line was devised to construct high-voltage high-speed pulse isolation transformers. The transmission lines can easily realize stable high-voltage operation and good impedance matching between primary and secondary circuits. The time constant for the step response of the transformer was calculated by introducing a simple low-frequency equivalent circuit model. Results show that the relation between the time constant and low-cut-off frequency of the transformer conforms to the theory of the general first-order linear time-invariant system. Results also show that the test transformer composed of the new transmission lines can transmit about 600 ps rise time pulses across the dc potential difference of more than 150 kV with insertion loss of -2.5 dB. The measured effective time constant of 12 ns agreed exactly with the theoretically predicted value. For practical applications involving the delivery of synchronized trigger signals to a dc high-voltage electron gun station, the transformer described in this paper exhibited advantages over methods using fiber optic cables for the signal transfer system. This transformer has no jitter or breakdown problems that invariably occur in active circuit components.

Development of spark cathode E-guns. Draft final reprt, Phase I, July--October 1978

International Nuclear Information System (INIS)

Loda, G.; Lindstrand, R.

1979-01-01

A 12 sided spark cathode is designed and constructed to replace the bladed, cold cathode structure in the electron gun of the Los Alamos Scientific Laboratory Antares prototype power amplifier. Design work includes computer modeling and full scale low voltage modeling. Life testing to 100,000 pulses is documented. The spark cathode offers precise control of emission site location and a high reliability

Creating intense polarized electron beam via laser stripping and spin-orbit interaction

International Nuclear Information System (INIS)

Danilov, V.; Ptitsyn, V.; Gorlov, T.

2010-01-01

The recent advance in laser field make it possible to excite and strip electrons with definite spin from hydrogen atoms. The sources of hydrogen atoms with orders of magnitude higher currents (than that of the conventional polarized electron cathods) can be obtained from H - sources with good monochromatization. With one electron of H - stripped by a laser, the remained electron is excited to upper state (2P 3/2 and 2P 1/2 ) by a circular polarization laser light from FEL. Then, it is excited to a high quantum number (n=7) with mostly one spin direction due to energy level split of the states with a definite direction of spin and angular momentum in an applied magnetic field and then it is stripped by a strong electric field of an RF cavity. This paper presents combination of lasers and fields to get high polarization and high current electron source.

Pulse Circuits of Radar Stations

Science.gov (United States)

1982-08-06

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

Small-Strip Thin Gap Chambers for the Muon Spectrometer Upgrade of the ATLAS Experiment

CERN Document Server

Perez Codina, Estel; The ATLAS collaboration

2015-01-01

For the forthcoming Phase-I upgrade to the LHC (2018/19), the first station of the ATLAS muon end-cap system, Small Wheel, needs to be replaced. The New Small Wheel (NSW) will have to operate in a high background radiation region while reconstructing muon tracks with high precision and providing information for the Level-1 trigger. In particular, the precision reconstruction of tracks requires a spatial resolution of about 100 μm, and the Level-1 trigger track segments have to be reconstructed with an angular resolution of approximately 1 mrad. The NSWs consist of eight layers each of Micromegas and small-strip Thin Gap Chambers (sTGC), both providing trigger and tracking capabilities. The single sTGC planes of a quadruplet consists of an anode layer of 50μm gold plated tungsten wire sandwiched between two resistive cathode layers. Behind one of the resistive cathode layers, a PCB with precise machined strips (thus the name sTGC) spaced every 3.2mm allows to achieve a position resolution that ranges from 70...

Plasma-induced field emission and plasma expansion of carbon nanotube cathodes

International Nuclear Information System (INIS)

Liao Qingliang; Zhang Yue; Qi Junjie; Huang Yunhua; Xia Liansheng; Gao Zhanjun; Gu Yousong

2007-01-01

High intensity electron emission cathodes based on carbon nanotube films have been successfully fabricated. An investigation of the explosive field emission properties of the carbon nanotube cathode in a double-pulse mode was presented and a high emission current density of 245 A cm -2 was obtained. The formation of the cathode plasma layer was proved and the production process of the electron beams from the cathode was explained. The time and space resolution of the electron beams flow from the cathode was investigated. The plasma expanded at a velocity of ∼8.17 cm μs -1 towards the anode and influenced on the intensity and distribution of electron beams obviously. The formation of cathode plasma had no preferential position and the local enhancement of electron beams was random. This carbon nanotube cathode appears to be suitable for high-power microwave device applications

Nanoparticles formation and deposition in the trichel pulse corona

International Nuclear Information System (INIS)

Amirov, R H; Samoylov, I S; Petrov, A A

2013-01-01

Cathode erosion in the negative corona discharge has been studied in the point-to-plane electrode configuration with Cu cathodes in the Trichel pulse regime. Redeposition of erosion products has been found on the cathode surface in form of agglomerates of 10-nm nanoparticles. Nanocraters and nanoparticles formation in the negative corona discharge has been considered in frames of electro-explosive mechanism of cathode erosion. According to this mechanism the cathode erosion is performed as a consequence of elementary erosion events each of which is caused by a Trichel pulse. A 1-dimentional model of corona-produced nanoparticles dynamics in the gap was elaborated. According to results of the simulation, the redeposition is explained by charging of the nanoparticles due to positive ions adsorption and thermionic emission. The size, temperature and initial velocity of the aerosol nanoparticles have the decisive action on redeposition in the negative corona discharge.

Electron source with a carbon-fibrous cathode for radiation-technology accelerator

International Nuclear Information System (INIS)

Korenev, S.A.

1994-01-01

The paper analyses the circuit of a full operating voltage electron source which is a direct-action electron accelerator. The electron source consists of a power supply, high-voltage multiplier-rectifier, vacuum planar diode, vacuum system and control system. The vacuum electron diode contains an autoemission carbon-fibrous cathode and beryllium foil strip anode. The results of measurements of emission characteristics of alumosilicate and carbon-fibrous cathodes are presented. The investigations into test electron source show that it can be used as a basis for creating an electron accelerator which will be capable of generating 1 MW electron beams of 1-2 MeV energy and 1 A current. 3 refs., 1 fig., 1 tab

Trace analysis of lead and cadmium in seafoods by differential pulse anodic stripping voltametry

International Nuclear Information System (INIS)

Sumera, F.C.; Verceluz, F.P.; Kapauan, P.A.

1979-01-01

A method for the simultaneous determination of cadmium and lead in seafoods is described. The sample is dry ashed in a muffle furnace elevating the temperature gradually up to 500 0 C. The ashed sample is treated with concentrated nitric acid, dried on a heating plate and returned to the muffle furnace for further heating. The treated ash is then dissolved in 1 N HCL acetate buffer and citric acid are added and the pH adjusted to 3.6-4. The resulting solution is analyzed for lead and cadmium by differential pulse anodic stripping voltametry (DPASV) using a wax-impregnated graphite thin film electrode. The average recoveries of 0.4 of cadmium and lead added to 5 fish samples were 97% and 99% respectively. The standard deviations, on a homogenized shark sample for lead and cadmium analysis were 6.7 ppb and 12.3 ppb, respectively, and the relative standard deviations were 21.0% and 15.5% respectively. Studies on instrumental parameters involved in the DPASV step of analysis and methods of measuring peak current signals were also made. (author)

Electron Sources of the Diode Type with Cathode and Anode of High Temperature Superconductors

International Nuclear Information System (INIS)

Korenev, S.A.

1994-01-01

The planar electron sources of the diode type with cathode and anode of high temperature superconductors (HTSC) are considered. Explosive emission cathode on the basis of bismuth ceramics (Bi-Ca-Sr-Cu-O) allows forming microsecond pulse (duration > 1 μs) and low energy electron beams (10-25 keV). Tube anode of HTSC in superconducting phase compresses the pulsed electron beam (K = 2-8). It leads to an increase of the beam power density. The high voltage of the generator of Arkad'ev-Marx type (U = 100-600 kV) and the generator with double L C-line are used for experiments. The pulsed method of measuring of the HTSC critical current with the help of pulsed high current electron beam is described. (author). 16 refs., 13 figs

Pulsed power supply system for neutron well logging

International Nuclear Information System (INIS)

Hopkinson, E.C.

1975-01-01

A variable D. C. power supply and a variable A. C. power supply are coupled onto the upper end of a single conductor cable at the earth's surface and from the lower end of said cable to a well logging instrument. The A. C. voltage is used to provide filament power for the ion source accelerator tube. The D. C. voltage is used to provide power to fixed D. C. loads maintained constant by regulators once a threshold is reached. The D. C. voltage is raised above the threshold to control the pulsed acceleration voltage and hence neutron output by first feeding into a unijunction relaxation oscillator in combination with an SCR output which output is transformer coupled into a voltage multiplier circuit. An antilatch feature is provided for the SCR by transformer coupling the pulses on the SCR anode back to the base of a transistor in series with the cathode of the SCR. Two outputs of the voltage multiplier circuit are connected to the cathode and anode, respectively, of an ion source accelerator tube, the cathode being connected through a resistor to retard the ripple pulsing of the cathode to allow ionization of the accelerator tube

Synchronization trigger for HSFC in the optical diagnosis of intense electron beam cathodes

International Nuclear Information System (INIS)

Yang Jie; Shu Ting; Zhang Jun; Yang Jianhua; Liu Lie; Yin Yi; Luo Ling

2010-01-01

This paper presents an intense electron beam cathodes optical diagnosis platform, which consists of an accelerator using a water-dielectric helical pulse forming line (PFL) and a high speed framing camera (HSFC-PRO) with an minimum exposure of 3 ns. HSFC-PRO must work synchronously with the explosive process of the intense electron beam cathodes in order to obtain correct data. On one hand, the high voltage electrical pulse from the PFL is delayed by a water-dielectric helix line with a nearly 110ns electrical length. On the other hand, The synchronization trigger signal for the HSFC-PRO is obtained from the pre d elayed high voltage electrical pulse from the PFL. A TTL signal (5 V) with rising edge is required to trigger the HSFC. The rise time (10% to 90%) should be <20ns. As a result, the negative-edge attenuated electrical pulse with a about 25 ns rise time from the PFL can not trigger the HSFC immediately.Consequently, the polarity of the attenuated high voltage electrical pulse from the PFL is reversed by a pulse transformer. Then it is converted subsequently into a TTL signal (5 V) with rising edge via a monostable multivibrator , The rise time (10% to 90%) is <5 ns, which is suitable for HSFC absequently. This established optical diagnosis platform can supply an electrical pulse with its output voltage of 200-400 kV, risetime of ∼35ns and pulse width(FWHM) of ∼110ns. By means of delaying the electrical pulse, the synchronization trigger problem of the HSFC-PRO has been solved properly, with correlative time precision of about ns level, which sets a running start for the following intensive research of explosive emission cathodes. (authors)

Isolated grid electron gun and pulser system for long/short pulse operation

International Nuclear Information System (INIS)

Koontz, R.F.; Feathers, L.; Kilbourne, C.; Leger, G.; McKinney, T.

1984-04-01

The new NPI gun at SLAC serves the dual functions of producing long pulse (up to 5 μsec, 180 pps) electron bursts for nuclear physics experiments, and also short (1 nsec) pulses for filling Stanford Synchrotron Radiation Laboratory (SSRL). This is accomplished by means of a newly designed, isolated grid gun, cathode pulsed with a solid state long pulse pulser, and grid pulsed with a fast recharging avalanche type short pulse (1 nsec) grid pulser. The grid pulser is bipolar so that a fast blackout notch can be placed in the long cathode pulse. This fast notch can be seen by Stanford Linear Collider (SLC) instrumentation and allows the long pulse beam to be computer controlled by SLC intensity and beam position monitors

Effects of Thickness, Pulse Duration, and Size of Strip Electrode on Ferroelectric Electron Emission of Lead Zirconate Titanate Films

Science.gov (United States)

Yaseen, Muhammad; Ren, Wei; Chen, Xiaofeng; Feng, Yujun; Shi, Peng; Wu, Xiaoqing

2018-02-01

Sol-gel-derived lead zirconate titanate (PZT) thin-film emitters with thickness up to 9.8 μm have been prepared on Pt/TiO2/SiO2/Si wafer via chemical solution deposition with/without polyvinylpyrrolidone (PVP) modification, and the relationship between the film thickness and electron emission investigated. Notable electron emission was observed on application of a trigger voltage of 120 V for PZT film with thickness of 1.1 μm. Increasing the film thickness decreased the threshold field to initiate electron emission for non-PVP-modified films. In contrast, the electron emission behavior of PVP-modified films did not show significant dependence on film thickness, probably due to their porous structure. The emission current increased with decreasing strip width and space between strips. Furthermore, it was observed that increasing the duration of the applied pulse increased the magnitude of the emission current. The stray field on the PZT film thickness was also calculated and found to increase with increasing ferroelectric sample thickness. The PZT emitters were found to be fatigue free up to 105 emission cycles. Saturated emission current of around 25 mA to 30 mA was achieved for the electrode pattern used in this work.

Evaluation of circulating cathodic antigen (CCA strip for diagnosis of urinary schistosomiasis in Hassoba school children, Afar, Ethiopia

Directory of Open Access Journals (Sweden)

Ayele B.

2008-03-01

Full Text Available A total of 206 urine samples collected from Hassoba Elementary schoolchildren, Afar, Ethiopia, a low Schistosoma haematobium endemic setting, was diagnosed to evaluate the performance of CCA strip using double references, urine filtration technique and urinalysis dipstick (Combur 10 Test® that detect schistosome eggs and blood in urine, respectively. The former was used as a gold standard reference method. Sensitivity, specificity, positive and negative predictive values for the CCA were 52%, 63.8%, 56.7% and 59% respectively, with reference to urine filtration technique whereas these parameters were 50.4%, 62.4%, 55.6% and 57.5% respectively, with reference to Combur 10 Test®. 47 S. haematobium egg-positive children were found negative by CCA strip while 38 egg-negative children were found positive by CCA strip. Moreover, among the pre-tests done in duplicate, inconsistent results were also recorded. Assays were also compared with regard to the cost of equipment and reagents, speed and simplicity of use. Though CCA strip was found to be rapid and could be performed with minimal training, it was found to be expensive (US $ 4.95 per test to use it for large-scale field use even if its diagnostic value would have been satisfactory. Further development and standardization of the CCA strip are required for its applicability for field use. It is also recommended that its cost per strip should be substantially cut down if it is to be used in poor schistosomiasis endemic countries.

Suppression and utilization of spurious pulse occurence in organic GM-counters

International Nuclear Information System (INIS)

Narita, Y.; Igarashi, R.; Akagami, H.; Ozawa, Y.

1979-01-01

The authors have made a study of suppression and utilization of spurious pulse occurrence in organic GM-counters. Almost all spurious pulses in the organic GM-counter are the delayed pulses which occur being dependent upon the radiation intensity. The occurrence rate of the delayed pulses against the radiation intensity is affected by the intensity of the electric field in the vicinity of the cathode of the GM-counter. The occurrence of the delayed pulses can be suppressed when the electric field in the vicinity of the cathode is kept at high value. On the contrary, the occurrence of the delayed pulses can be utilized for the dosimetry of the pulsed radiation by means of increasing the space of the weak electric field in the GM-counter. (Auth.)

Comparative Studies of the Speciation Patterns of Nickel and ...

African Journals Online (AJOL)

Results of speciation stdies of nickel and chromium in wastewater, surface and groundwater systems using flame atomic absorption spectrometry (FAAS), graphite furnace atomic absorption spectrometry (GFAAS) and differential pulse adsorptive cathodic stripping voltammetry (DPAdCSV) are presented. Dimethylglyoxime ...

Raman Spectroscopy of DLC/a-Si Bilayer Film Prepared by Pulsed Filtered Cathodic Arc

Directory of Open Access Journals (Sweden)

C. Srisang

2012-01-01

Full Text Available DLC/a-Si bilayer film was deposited on germanium substrate. The a-Si layer, a seed layer, was firstly deposited on the substrate using DC magnetron sputtering and DLC layer was then deposited on the a-Si layer using pulsed filtered cathodic arc method. The bilayer films were deposited with different DLC/a-Si thickness ratios, including 2/2, 2/6, 4/4, 6/2, and 9/6. The effect of DLC/a-Si thickness ratios on the sp3 content of DLC was analyzed by Raman spectroscopy. The results show that a-Si layer has no effect on the structure of DLC film. Furthermore, the upper shift in G wavenumber and the decrease in ID/IG inform that sp3 content of the film is directly proportional to DLC thickness. The plot modified from the three-stage model informed that the structural characteristics of DLC/a-Si bilayer films are located close to the tetrahedral amorphous carbon. This information may be important for analyzing and developing bilayer protective films for future hard disk drive.

The application and study of an oxide-impregnated nickel-matrix cathode for Beijing proton linac

International Nuclear Information System (INIS)

Xia Dehong; Shi Rongjian

1996-01-01

A low power consumption oxide-impregnated nickel-matrix cathode used in the Duoplasmatron ion source of the Beijing Proton Linac (BPL) is presented. Its structure, treatment process of nickel-foam rubber on metal matrix surface and manufacture of dip coating carbonate are briefly introduced. The activation method and experiment results of the cathode are described. The principal factors which influence the cathode lifetime are discussed. The lifetime of the cathode is up to 2110 h while the extracted pulsed beam current is about 200 mA

Dynamic Characterizations of an 8-frame, Half-Strip, High-speed X-ray Microchannel Plate Imager

International Nuclear Information System (INIS)

Ken Moy; Ming Wu; Craig Kruschwitz; Aric Tibbits; Matt Griffin; Greg Rochau

2008-01-01

High-speed microchannel plate (MCP)-based imagers are critical detectors for x-ray diagnostics employed on Z-experiments at Sandia National Laboratories (SNL) to measure time-resolved x-ray spectra and to image dynamic hohlraums. A multiframe design using eight half strips in one imager permits recordings of radiation events in discrete temporal snapshots to yield a time-evolved movie. We present data using various facilities to characterize the performance of this design. These characterization studies include DC and pulsed-voltage biased measurements in both saturated and linear operational regimes using an intense, short-pulsed UV laser. Electrical probe measurements taken to characterize the shape of the HV pulse propagating across the strips help to corroborate the spatial gain dependence

Increased sensitivity of anodic stripping voltammetry at the hanging mercury drop electrode by ultracathodic deposition.

Science.gov (United States)

Rodrigues, José A; Rodrigues, Carlos M; Almeida, Paulo J; Valente, Inês M; Gonçalves, Luís M; Compton, Richard G; Barros, Aquiles A

2011-09-09

An improved approach to the anodic stripping voltammetric (ASV) determination of heavy metals, using the hanging mercury drop electrode (HMDE), is reported. It was discovered that using very cathodic accumulation potentials, at which the solvent reduction occurs (overpotential deposition), the voltammetric signals of zinc(II), cadmium(II), lead(II) and copper(II) increase. When compared with the classical methodology a 5 to 10-fold signal increase is obtained. This effect is likely due to both mercury drop oscillation at such cathodic potentials and added local convection at the mercury drop surface caused by the evolution of hydrogen bubbles. Copyright © 2011 Elsevier B.V. All rights reserved.

Experimental research of double-pulse linear induction electron accelerator

International Nuclear Information System (INIS)

Liao Shuqing; Cheng Cheng; Zheng Shuxin; Tang Chuanxiang; Lin Yuzheng; Jing Xiaobing; Mu Fan; Pan Haifeng

2009-01-01

The Mini-LIA is a double-pulse linear induction electron accelerator with megahertz repetition rates, which consists of a double-pulse power system, a thermal cathode electron gun, two induction cells, beam transportation systems and diagnosis systems, etc. Experiments of the Mini-LIA have been conducted. The double-pulse high voltage was obtained with several hundred nanosecond pulse intervals (i. e. megahertz repetition rate) and each pulse had an 80 kV amplitude with a FWHM of 80 ns. In the gap of the induction cell, the double-pulse accelerating electric field was measured via E-field probes, and the double-pulse electron beam with a current about 1.1 A has been obtained at the Mini-LIA exit. These experimental results show that the double-pulse high voltage with megahertz repetition rates can be generated by an insulation and junction system. And they also indicate that the induction cell with metglas as the ferromagnetic material and the LaB 6 thermal cathode electron gun suit the double-pulse operation with megahertz repetition rates. (authors)

Discharge behavior of vacuum arc ion source working in pulse mode

International Nuclear Information System (INIS)

Tang Pingying; Dai Jingyi; Tan Xiaohua; Jin Dazhi; Liu Tie; Ding Bonan

2005-01-01

Discharge behavior of the vacuum arc ion source working in pulse mode was investigated using high-speed photography and spectrum diagnosis. The evolvement of cathode spot on hydrogen-impregnated electrode was captured by high-speed photography, and the emission spectra of cathode spot at different pulse currents were analyzed. The experimental results show that in most cases, only one cathode spot can be found in the discharge zone of vacuum arc ion source, and the spot moves a little during the same discharge. Temperature of the cathode spot may rise while the discharge current increases, and ultimately the density of hydrogen ion will be increased. At the same time, sputtering of the electrode is enhanced and the quality of ion plasma will be reduced. (authors)

Pulse seed germination improves antioxidative activity of phenolic compounds in stripped soybean oil-in-water emulsions.

Science.gov (United States)

Xu, Minwei; Jin, Zhao; Peckrul, Allen; Chen, Bingcan

2018-06-01

The purpose of this study was to investigate antioxidative activity of phenolic compounds extracted from germinated pulse seed including chickpeas, lentils and yellow peas. Phenolic compounds were extracted at different germination time and total phenolic content was examined by Folin Ciocalteu's reaction. Antioxidative activity of extracts was characterized by in vitro assay including 2, 2-diphenyl-1-picrylhydrazyl radical scavenging capacity (DPPH), oxygen radical absorbance capacity (ORAC), iron-binding assay, and in stripped soybean oil-in-water emulsions. The results suggested that germination time is critical for phenolic compounds production. The form variation of phenolic compounds influenced the antioxidative activity of phenolic compounds both in vitro assay and in emulsion systems. Soluble bound phenolic compounds showed higher antioxidative ability in emulsion system with the order of chickpea > yellow pea > lentil. On the basis of these results, soluble bound phenolic compounds may be considered as a promising natural antioxidant to prevent lipid oxidation in foods. Copyright © 2018 Elsevier Ltd. All rights reserved.

UV photoemission from metal cathodes for picosecond power switches

International Nuclear Information System (INIS)

Fischer, J.; Srinivasan-RAo, T.; Tsang, T.

1989-01-01

Results are reported of photoemission studies using laser pulses of 10 ps duration and 4.66 eV photon energy on metal cathodes. These included thin wires, flat surfaces and an yttrium cathode with a grainy surface. The measurements of current density and quantum efficiency under low and high surface fields indicate that field assisted efficiencies exceeding 0.1% and current densities exceeding 10 5 A/cm 2 are obtainable. The results are compared to the requirements of switch power applications. 24 refs., 13 figs., 1 tab

An isolated grid electron gun and pulser system for long/short pulse operation

International Nuclear Information System (INIS)

Koontz, R.F.; Feathers, L.; Kilbourne, C.; Leger, G.; McKinney, T.

1984-01-01

The new NPI gun at SLAC serves the dual functions of producing long pulse (up to 5 μsec, 180 pps) electron bursts for nuclear physics experiments, and also short ( 1 nsec) pulses for filling Stanford Synchrotron Radiation Laboratory (SSRL). This is accomplished by means of a newly designed, isolated grid gun, cathode pulsed with a solid state long pulse pulser, and grid pulsed with a fast recharging avalanche type short pulse (1 nsec) grid pulser. The grid pulser is bipolar so that a fast blackout notch can be placed in the long cathode pulse. This fast notch can be seen by Stanford Linear Collider (SLC) instrumentation and allows the long pulse beam to be computer controlled by SLC intensity and beam position monitors. (orig.)

Focused cathode design to reduce anode heating during vircator operation

Energy Technology Data Exchange (ETDEWEB)

Lynn, Curtis F.; Dickens, James C.; Neuber, Andreas A. [Center for Pulsed Power and Power Electronics, Department of Electrical and Computer Engineering, Texas Tech University, Lubbock, Texas 79409 (United States)

2013-10-15

Virtual cathode oscillators, or vircators, are a type of high power microwave device which operates based on the instability of a virtual cathode, or cloud of electrons, which forms when electron current injected into the drift tube exceeds the space charge limited current within the drift tube. Anode heating by the electron beam during vircator operation ultimately limits achievable pulse lengths, repetition rates, and the duration of burst mode operation. This article discusses a novel cathode design that focuses electrons through holes in the anode, thus significantly reducing anode heating by the electrons emitted from the cathode during the first transit through the A-K gap. Reflexing electrons continue to deposit energy on the anode; however, the discussed minimization of anode heating by main beam electrons has the potential to enable higher repetition rates as well as efficiency and longer diode lifetime. A simulation study of this type of cathode design illustrates possible advantages.

Pulsed neutron source well logging system

International Nuclear Information System (INIS)

Dillingham, M.E.

1975-01-01

A pulsed neutron source with a chamber containing a plurality of alpha emitting strips and beryllium targets coaxially mounted is described. A pulsed source is provided by rotation of the target to on-off positions along with electromagnetic and magnetic devices for positive locking and rotation. (U.S.)

200 keV electron beam pulse source for the complex VEPP-5 preinjector

CERN Document Server

Akimov, V E; Korepanov, A A

2001-01-01

The electron beam source based on GS-34 valve cathode-grid unit with oxide cathode of 12 mm in diameter is described. Originally the high voltage DC source was used to supply the gun. The cathode emission characteristic was reduced by the vacuum breakdowns during gun operation. So the necessity of decreasing a high voltage from 200 kV to 140 kV has appeared. The use of the pulse transformer based gun supply with a pulse duration of approx 1 mcs provided the gun operation without breakdowns at a voltage of 200 kV and pulse repetition rate up to 50 Hz. At present time the electron source is operated at the complex VEPP-5 preinjector.

Effect of paraelectrode processes on contraction of space charge in periodic-pulse lasers

Science.gov (United States)

Arytyunyan, R. V.; Baranov, V. Yu.; Borisov, V. M.; Vinokhodov, A. Yu.; Kiryukhin, Yu. B.

1986-05-01

A characteristic feature of periodic-pulse electric-discharge CO2-lasers and excimer lasers is contraction of the space charge as the pulse repetition rate increases. The emission energy per pulse decreases as a consequence, with the average laser power first ceasing to increase linearly beyond a certain corner repetition rate and then decreasing beyond a certain critical repetition rate. A study of this phenomenon was made, for the purpose of separating the effect of paracathode processes from the effect of gas dynamics and then evaluating the effect of the former alone. Paraelectrode perturbations were simulated by focusing the radiation from the an XeCl-laser on the cathode surface in an atmosphere of nonabsorbing gases. Laser pulses of up to approximately 0.5 J energy and of approximately 50 ns duration were focused within a spot of 1 mm(2) area on a cathode inside a discharge chamber, with the power density of incident radiation regulated by means of an attenuator. A space charge within a volume of 2.5x4.5x9 cm(3) was generated between this specially shaped cathode and a mesh anode with an approximately 50% optical transmission coefficient. The space charge in helium and in neon was photographed, and the time lag of a discharge pulse behind a contracting laser pulse was measured as a function of the laser pulse energy for these two gases, as well as for a He+C12 gas mixture. The general trend was found to be the same in each case, the time lag increasing with increasing energy first at a slower rate up to a critical energy level and then faster. It has been established that plasma does not build up on the cathode before the laser pulse energy reaches 30 mJ (for a 3 mm(2) surface area), while plasma glow begins as the laser pulse energy reaches 150 mJ. A contracted channel begins to form within the laser-cathode interaction space, with an attendant fast increase of the time lag owing to evaporation of the cathode metal.

Optimization of cathodic arc deposition and pulsed plasma melting techniques for growing smooth superconducting Pb photoemissive films for SRF injectors

Science.gov (United States)

Nietubyć, Robert; Lorkiewicz, Jerzy; Sekutowicz, Jacek; Smedley, John; Kosińska, Anna

2018-05-01

Superconducting photoinjectors have a potential to be the optimal solution for moderate and high current cw operating free electron lasers. For this application, a superconducting lead (Pb) cathode has been proposed to simplify the cathode integration into a 1.3 GHz, TESLA-type, 1.6-cell long purely superconducting gun cavity. In the proposed design, a lead film several micrometres thick is deposited onto a niobium plug attached to the cavity back wall. Traditional lead deposition techniques usually produce very non-uniform emission surfaces and often result in a poor adhesion of the layer. A pulsed plasma melting procedure reducing the non-uniformity of the lead photocathodes is presented. In order to determine the parameters optimal for this procedure, heat transfer from plasma to the film was first modelled to evaluate melting front penetration range and liquid state duration. The obtained results were verified by surface inspection of witness samples. The optimal procedure was used to prepare a photocathode plug, which was then tested in an electron gun. The quantum efficiency and the value of cavity quality factor have been found to satisfy the requirements for an injector of the European-XFEL facility.

Characterization and Calibration of Large Area Resistive Strip Micromegas Detectors

CERN Document Server

Losel, Philipp Jonathan; The ATLAS collaboration

2015-01-01

Resisitve strip Micromegas detectors behave discharge tolerant. They have been tested extensively as smaller detectors of about 10 x 10 cm$^2$ in size and they work reliably at high rates of 100\\,kHz/cm$^2$ and above. Tracking resolutions well below 100\\,$\\mu$m have been observed for 100 GeV muons and pions. Micromegas detectors are meanwhile proposed as large area muon precision trackers of 2-3\\,m$^2$ in size. To investigate possible differences between small and large detectors, a 1\\,m$^2$ detector with 2048 resistive strips at a pitch of 450 $\\mu$m was studied in the LMU Cosmic Ray Facility (CRF) using two 4 $\\times$ 2.2 m$^2$ large Monitored Drift Tube (MDT) chambers for cosmic muon reference tracking. Segmentation of the resistive strip anode plane in 57.6\\,mm x 95\\,mm large areas has been realized by the readout of 128 strips with one APV25 chip each and by 11 95\\,mm broad trigger scintillators placed along the readout strips.\\\\ This allows for mapping of homogenity in pulse height and efficiency, deter...

Temporal development of the composition of Zr and Cr cathodic arc plasma streams in a N2 environment

International Nuclear Information System (INIS)

Rosen, Johanna; Anders, Andre; Hultman, Lars; Schneider, Jochen M.

2003-01-01

We describe the temporal development of the plasma composition in a pulsed plasma stream generated by cathodic arc. Cathodes of Zr and Cr were operated at various nitrogen pressures. The time-resolved plasma composition for the cathode materials was analyzed with time-of-flight charge-to-mass spectrometry, and was found to be a strong function of the nitrogen pressure. Large plasma composition gradients were detected within the first 60 μs of the pulse, the nitrogen ion concentration increasing with increasing pressure. The results are explained by the formation and erosion of a compound layer formed at the cathode surface in the presence of a reactive gas. The average charge state was also found to be affected by the reactive gas pressure as well as by the time after ignition. The charge states were highest in the beginning of the pulse at low nitrogen pressure, decreasing to a steady-state value at higher pressure. These results are of importance for reactive plasma processing and for controlling the evolution of thin film composition and microstructure

Low-resistance strip sensors for beam-loss event protection

International Nuclear Information System (INIS)

Ullán, M.; Benítez, V.; Quirion, D.; Zabala, M.; Pellegrini, G.; Lozano, M.; Lacasta, C.; Soldevila, U.; García, C.; Fadeyev, V.; Wortman, J.; DeFilippis, J.; Shumko, M.; Grillo, A.A; Sadrozinski, H.F.-W.

2014-01-01

AC-coupled silicon strip sensors can be damaged in case of a beam loss due to the possibility of a large charge accumulation in the bulk, developing very high voltages across the coupling capacitors which can destroy them. Punch-through structures are currently used to avoid this problem helping to evacuate the accumulated charge as large voltages are developing. Nevertheless, previous experiments, performed with laser pulses, have shown that these structures can become ineffective in relatively long strips. The large value of the implant resistance can effectively isolate the “far” end of the strip from the punch-through structure leading to large voltages. We present here our developments to fabricate low-resistance strip sensors to avoid this problem. The deposition of a conducting material in contact with the implants drastically reduces the strip resistance, assuring the effectiveness of the punch-through structures. First devices have been fabricated with this new technology. Initial results with laser tests show the expected reduction in peak voltages on the low resistivity implants. Other aspects of the sensor performance, including the signal formation, are not affected by the new technology

Strip interpolation in silicon and germanium strip detectors

International Nuclear Information System (INIS)

Wulf, E. A.; Phlips, B. F.; Johnson, W. N.; Kurfess, J. D.; Lister, C. J.; Kondev, F.; Physics; Naval Research Lab.

2004-01-01

The position resolution of double-sided strip detectors is limited by the strip pitch and a reduction in strip pitch necessitates more electronics. Improved position resolution would improve the imaging capabilities of Compton telescopes and PET detectors. Digitizing the preamplifier waveform yields more information than can be extracted with regular shaping electronics. In addition to the energy, depth of interaction, and which strip was hit, the digitized preamplifier signals can locate the interaction position to less than the strip pitch of the detector by looking at induced signals in neighboring strips. This allows the position of the interaction to be interpolated in three dimensions and improve the imaging capabilities of the system. In a 2 mm thick silicon strip detector with a strip pitch of 0.891 mm, strip interpolation located the interaction of 356 keV gamma rays to 0.3 mm FWHM. In a 2 cm thick germanium detector with a strip pitch of 5 mm, strip interpolation of 356 keV gamma rays yielded a position resolution of 1.5 mm FWHM

Increased sensitivity of anodic stripping voltammetry at the hanging mercury drop electrode by ultracathodic deposition

Energy Technology Data Exchange (ETDEWEB)

Rodrigues, Jose A.; Rodrigues, Carlos M.; Almeida, Paulo J.; Valente, Ines M.; Goncalves, Luis M. [Requimte - Departamento de Quimica e Bioquimica, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre, no. 687, 4169-007 Porto (Portugal); Compton, Richard G. [Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ (United Kingdom); Barros, Aquiles A., E-mail: ajbarros@fc.up.pt [Requimte - Departamento de Quimica e Bioquimica, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre, no. 687, 4169-007 Porto (Portugal)

2011-09-09

Highlights: {yields} At very cathodic accumulation potentials (overpotential deposition) the voltammetric signals of Zn{sup 2+}, Cd{sup 2+}, Pb{sup 2+} and Cu{sup 2+} increase. {yields} 5 to 10-fold signal increase is obtained. {yields} This effect is likely due to mercury drop oscillation at such cathodic potentials. {yields} This effect is also likely due to added local convection at the mercury drop surface caused by the evolution of hydrogen bubbles. - Abstract: An improved approach to the anodic stripping voltammetric (ASV) determination of heavy metals, using the hanging mercury drop electrode (HMDE), is reported. It was discovered that using very cathodic accumulation potentials, at which the solvent reduction occurs (overpotential deposition), the voltammetric signals of zinc(II), cadmium(II), lead(II) and copper(II) increase. When compared with the classical methodology a 5 to 10-fold signal increase is obtained. This effect is likely due to both mercury drop oscillation at such cathodic potentials and added local convection at the mercury drop surface caused by the evolution of hydrogen bubbles.

Pulsed hollow cathode discharge: intense electron beam and filamentary plasma

International Nuclear Information System (INIS)

Modreanu, Gabriel

1998-01-01

This work deals with a transient hollow cathode discharge optimised by a preionization one and providing intense electron beams. It exists a preionization current value for which the pulsed discharge becomes a very straight and bright filament, well collimated on the discharge tube axis for some tenths of centimeters. A remarkable feature of this discharge is that, without internal metallic electrodes very pure plasma could be produced. Using self-biasing by the beam of a Faraday cup placed only few millimeters behind the anode, we deduced the beam electron's distribution function and its temporal behavior for two radial positions, on the axis and 1 millimeter off-axis, respectively. The real advantage of this measurement technique is the transient polarization character, which allows analysis very closely from the electron beam extraction hole. On the other side, using the emission spectroscopy, we have studied the plasma produced in electron beam - gas interaction and deduced the temporal evolution of the electron temperature. The temporal behavior of the filamentary plasma diameter shows a constriction at the last moments of the beam existence, followed by diffusion controlled expansion. The ambipolar diffusion coefficient corresponding to the estimated electron temperature describes quite well this expansion and allows a quantitative interpretation of the measured temperature diminution, with taking into account the preferential fast electrons escape. The analysis of both beam and post-beam plasma phases suggests potential applications of this robust, very reproducible and not expensive discharge also susceptible to be external monitored. The beam - target interaction could be used for PVD, elementary analysis and filamentary or point-like X-ray emission. (author) [fr

High-power microwave generation from a frequency-stabilized virtual cathode source

International Nuclear Information System (INIS)

Fazio, M.V.; Hoeberling, R.F.; Kinross-Wright, J.

1988-01-01

The evolution of virtual cathode based high-power microwave-source technology has been directed primarily toward achieving higher peak-power levels. As peak powers in excess of 10 GW have been reported, attention has begun to focus on techniques for producing a more frequency- and phase-stable virtual cathode source. Free-running virtual cathode microwave sources characteristically exhibit bandwidths in a single pulse of tens of percent, which makes them unsuitable for many applications such as power sources for phased array antennas and microwave linear accelerators. Presented here are results of an experimental approach utilizing a high-Q, resonant cavity surrounding the oscillating virtual cathode to achieve frequency stabilization and repeatable narrow-band operation. A cylindrical cavity resonator is used with the microwave power being extracted radially through circumferential slot apertures into L-band waveguide

[Atomic/ionic fluorescence in microwave plasma torch discharge with excitation of high current and microsecond pulsed hollow cathode lamp: Ca atomic/ionic fluorescence spectrometry].

Science.gov (United States)

Gong, Zhen-bin; Liang, Feng; Yang, Peng-yuan; Jin, Qin-han; Huang, Ben-li

2002-02-01

A system of atomic and ionic fluorescence spectrometry in microwave plasma torch (MPT) discharge excited by high current microsecond pulsed hollow cathode lamp (HCMP HCL) has been developed. The operation conditions for Ca atomic and ionic fluorescence spectrometry have been optimized. Compared with atomic fluorescence spectrometry (AFS) in argon microwave induced plasma (MIP) and MPT with the excitation of direct current and conventional pulsed HCL, the system with HCMP HCL excitation can improve AFS and ionic fluorescence spectrometry (IFS) detection limits in MPT atomizer and ionizer. Detection limits (3 sigma) with HCMP HCL-MPT-AFS/IFS are 10.1 ng.mL-1 for Ca I 422.7 nm, 14.6 ng.mL-1 for Ca II 393.4 nm, and 37.4 ng.mL-1 for Ca II 396.8 nm, respectively.

A study of junction effect transistors and their roles in carbon nanotube field emission cathodes in compact pulsed power applications

Science.gov (United States)

Shui, Qiong

This thesis is focusing on a study of junction effect transistors (JFETs) in compact pulsed power applications. Pulsed power usually requires switches with high hold-off voltage, high current, low forward voltage drop, and fast switching speed. 4H-SiC, with a bandgap of 3.26 eV (The bandgap of Si is 1.12eV) and other physical and electrical superior properties, has gained much attention in high power, high temperature and high frequency applications. One topic of this thesis is to evaluate if 4H-SiC JFETs have a potential to replace gas phase switches to make pulsed power system compact and portable. Some other pulsed power applications require cathodes of providing stable, uniform, high electron-beam current. So the other topic of this research is to evaluate if Si JFET-controlled carbon nanotube field emitter cold cathode will provide the necessary e-beam source. In the topic of "4H-SiC JFETs", it focuses on the design and simulation of a novel 4H-SiC normally-off VJFET with high breakdown voltage using the 2-D simulator ATLAS. To ensure realistic simulations, we utilized reasonable physical models and the established parameters as the input into these models. The influence of key design parameters were investigated which would extend pulsed power limitations. After optimizing the key design parameters, with a 50-mum drift region, the predicted breakdown voltage for the VJFET is above 8kV at a leakage current of 1x10-5A/cm2 . The specific on-state resistance is 35 mO·cm 2 at VGS = 2.7 V, and the switching speed is several ns. The simulation results suggest that the 4H-SiC VJFET is a potential candidate for improving switching performance in repetitive pulsed power applications. To evaluate the 4H-SiC VJFETs in pulsed power circuits, we extracted some circuit model parameters from the simulated I-V curves. Those parameters are necessary for circuit simulation program such as SPICE. This method could be used as a test bench without fabricating the devices to

Lithium recycling and cathode material regeneration from acid leach liquor of spent lithium-ion battery via facile co-extraction and co-precipitation processes.

Science.gov (United States)

Yang, Yue; Xu, Shengming; He, Yinghe

2017-06-01

A novel process for extracting transition metals, recovering lithium and regenerating cathode materials based on facile co-extraction and co-precipitation processes has been developed. 100% manganese, 99% cobalt and 85% nickel are co-extracted and separated from lithium by D2EHPA in kerosene. Then, Li is recovered from the raffinate as Li 2 CO 3 with the purity of 99.2% by precipitation method. Finally, organic load phase is stripped with 0.5M H 2 SO 4 , and the cathode material LiNi 1/3 Co 1/3 Mn 1/3 O 2 is directly regenerated from stripping liquor without separating metal individually by co-precipitation method. The regenerative cathode material LiNi 1/3 Co 1/3 Mn 1/3 O 2 is miro spherical morphology without any impurities, which can meet with LiNi 1/3 Co 1/3 Mn 1/3 O 2 production standard of China and exhibits good electrochemical performance. Moreover, a waste battery management model is introduced to guarantee the material supply for spent battery recycling. Copyright © 2017 Elsevier Ltd. All rights reserved.

Determination of picomolar silver concentrations by differential pulse anodic stripping voltammetry at a carbon paste electrode modified with phenylthiourea-functionalized high ordered nanoporous silica gel

International Nuclear Information System (INIS)

Javanbakht, Mehran; Divsar, Faten; Badiei, Alireza; Fatollahi, Fatemeh; Khaniani, Yeganeh; Ganjali, Mohammad Reza; Norouzi, Parviz; Chaloosi, Marzieh; Ziarani, Ghodsi Mohammadi

2009-01-01

This study introduces the design of an anodic stripping voltammetric (ASV) method for the silver ion determination at a carbon paste electrode (CPE), chemically modified with phenylthiourea-nanoporous silica gel (Tu-SBA-15-CPE). The electroanalytical pro includes two steps: preconcentration of metal ions at an electrode surface, followed by quantification of the accumulated species by differential pulse anodic stripping voltammetric methods. Factors affecting the performance of the anodic stripping were investigated, including the modifier quantity in the paste, the electrolyte concentrations, the solution pH and the accumulation potential or time. The most sensitive and reliable electrode contained 10% Tu-SBA-15 and 90% carbon paste. The accumulation potential and time were set at, -200 mV and 300 s, respectively, and the scan rate at 50 mV s -1 in the scan range of -200 to 700 mV. The resulting electrode demonstrated a linear response over range of silver ion concentration of 8.0-80 pmol/L with detection limit (S/N = 3) of 5 pmol/L. The prepared electrodes were used for the silver determination in sea and tap water samples and very good recovery results were obtained. The accuracy was assessed through recovery experiments and independent analysis by graphite furnace atomic absorption spectrometry.

Determination of picomolar silver concentrations by differential pulse anodic stripping voltammetry at a carbon paste electrode modified with phenylthiourea-functionalized high ordered nanoporous silica gel

Energy Technology Data Exchange (ETDEWEB)

Javanbakht, Mehran [Department of Chemistry, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Nano Science and Technology Research Center, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of)], E-mail: mehranjavanbakht@gmail.com; Divsar, Faten [Department of Chemistry, University of Tarbiat Moallem, Tehran (Iran, Islamic Republic of); Badiei, Alireza [School of Chemistry, University College of Science, University of Tehran, Tehran (Iran, Islamic Republic of); Fatollahi, Fatemeh [Department of Chemistry, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Khaniani, Yeganeh [School of Chemistry, University College of Science, University of Tehran, Tehran (Iran, Islamic Republic of); Ganjali, Mohammad Reza; Norouzi, Parviz [Center of Excellence in Electrochemistry, Faculty of Chemistry, University of Tehran, Tehran (Iran, Islamic Republic of); Chaloosi, Marzieh [Department of Chemistry, University of Tarbiat Moallem, Tehran (Iran, Islamic Republic of); Ziarani, Ghodsi Mohammadi [Department of Chemistry, University of Alzahra, Tehran (Iran, Islamic Republic of)

2009-09-30

This study introduces the design of an anodic stripping voltammetric (ASV) method for the silver ion determination at a carbon paste electrode (CPE), chemically modified with phenylthiourea-nanoporous silica gel (Tu-SBA-15-CPE). The electroanalytical pro includes two steps: preconcentration of metal ions at an electrode surface, followed by quantification of the accumulated species by differential pulse anodic stripping voltammetric methods. Factors affecting the performance of the anodic stripping were investigated, including the modifier quantity in the paste, the electrolyte concentrations, the solution pH and the accumulation potential or time. The most sensitive and reliable electrode contained 10% Tu-SBA-15 and 90% carbon paste. The accumulation potential and time were set at, -200 mV and 300 s, respectively, and the scan rate at 50 mV s{sup -1} in the scan range of -200 to 700 mV. The resulting electrode demonstrated a linear response over range of silver ion concentration of 8.0-80 pmol/L with detection limit (S/N = 3) of 5 pmol/L. The prepared electrodes were used for the silver determination in sea and tap water samples and very good recovery results were obtained. The accuracy was assessed through recovery experiments and independent analysis by graphite furnace atomic absorption spectrometry.

Pulsed high-current electron source: Final report

International Nuclear Information System (INIS)

Spindt, C.A.

1988-10-01

The objective of this investigation was to investigate ways to realize the cathode's potential as a source for high power pulse operation. The questions that needed to be studied were those of large area coverage, maximum emission that the cathode arrays are capable of producing practically, uniformity of emission over large areas, and the ability to operate with high voltage anodes. 9 figs

Cathode cooling systems for the magnetron and Penning H- sources: a progress report of work at Brookhaven National Laboratory

International Nuclear Information System (INIS)

McKenzie-Wilson, R.B.

1977-01-01

The magnetron/Penning H - sources being developed at Brookhaven National Laboratory have produced ion currents up to 1 A with pulse lengths of 10 ms. The pulse length is limited by heating of the cathode surface. Cathode thermal conditions were investigated and lead to the conclusion that a cathode cooling system must be capable of handling 3 kW cm -2 of heated cathode surface. A review of cooling fluid requirements coupled with an examination of possible cooling fluids, leads to the conclusion that demineralized water is a suitable cooling fluid when used under pressurized nucleated boiling conditions. A correlation is used to show that heat-flux of 1.25 kW cm -2 could be removed using current technology and that this heat flux may be extended to 3 kW cm -2 by use of the Hyper-Vapotron effect. The temperature of the working surface of the cathode may be varied over a small temperature range by varying the system pressure during operation

Organic complexation of iron in the West Atlantic Ocean

NARCIS (Netherlands)

Gerringa, L.J.A.; Rijkenberg, M.J.; Schoemann, V.; Laan, P.; de Baar, H.J.W.

2015-01-01

The characteristics of the dissolved iron (DFe) binding organic ligands were determined during 3 Dutch GEOTRACES cruises covering the length of the West Atlantic Ocean. Adsorptive Differential Pulse Cathodic Stripping Voltammetry (AdDPCSV) with TAC as competing ligand was used to measure Fe binding

Stability of high current diode under 100-nanosecond-pulse voltage

International Nuclear Information System (INIS)

Lai Dingguo; Qiu Aici; Zhang Yongmin; Huang Jianjun; Ren Shuqing; Yang Li

2012-01-01

Stability of high current diode under pulse voltage with 80 ns and 34 ns rise time was studied on the flash Ⅱ accelerator. Influence of rise time of diode voltage on startup time and cathode emission uniformity and repeatability of diode impedance was analyzed by comparing the experimental results with numerically simulated results, and the influence mechanism was discussed. The startup time of diode increases with the increasing of rise time of voltage, and the repeatability of diode impedance decreases. Discal plane cathode is prone to emit rays intensely in the center area, the time that plasma covers the surface of the cathode increases and the shielding effect has more impact on cathode emission according to the increase of rise time. Local intense emission on the cathode increases expansion speed of plasma and reduces the effective emission area. The stability of characteristic impedance of diode under a pulse voltage with slow rise time is decreased by the combined action of expansion speed of plasma and the effective emission area. (authors)

Characterization of Pulse Reverses Electroforming on Hard Gold Coating.

Science.gov (United States)

Byoun, Young-Min; Noh, Young-Tai; Kim, Young-Geun; Ma, Seung-Hwan; Kim, Gwan-Hoon

2018-03-01

Effect of pulse reverse current (PRC) method on brass coatings electroplated from gold solution was investigated by various plating parameters such as plating duration, the anodic duty cycle, the anodic current density and the cathodic current density. The reversed current results in a significant change in the morphology of electrodeposits, improvement of the overall current efficiency and reduction of deposit porosity. With longer pulses, hemispherical surface features are generated, while larger grains result from shorter pulse widths. The porosity of the plated samples is found to decrease compared with results at the same time-average plating rate obtained from DC or Pulse plating. A major impediment to reducing gold later thickness is the corrosion of the underlying substrate, which is affected by the porosity of the gold layer. Both the morphology and the hydrogen evolution reaction have significant impact on porosity. PRC plating affect hydrogen gold and may oxidize hydrogen produced during the cathodic portion of the waveform. Whether the dissolution of gold and oxidation of hydrogen occur depends on the type of plating bath and the plating conditions adapted. In reversed pulse plating, the amount of excess near-surface cyanide is changed after the cathodic current is applied, and the oxidation of gold under these conditions has not been fully addressed. The effects of the current density, pulse-reverse ratio and brightener concentration of the electroplating process were investigated and optimized for suitable performance.

Incomplete charge collection in an HPGe double-sided strip detector

International Nuclear Information System (INIS)

Hayward, Jason; Wehe, David

2008-01-01

For gamma-ray detection, high-purity germanium (HPGe) has long been the standard for energy resolution, and double-sided strip detectors (DSSDs) offer the possibility of sub-millimeter position resolution. Our HPGe DSSD is 81 mm in diameter, 11-mm thick, and has 3-mm strip pitch with a gap width of 500 μm. In this work, we focus on characterizing just the interactions that occur between collecting strips. Simulation and measurement results for our HPGe DSSD show that the gap between strips is the most position-sensitive region. But, spectra collected from events that occur in and near the gaps are complicated by: (1) incomplete charge-carrier collection, or charge loss; (2) signal variance introduced by charge-carrier cloud size, orientation, and lateral spreading; and (3) the difficulty of distinguishing single interactions from multiple close interactions. Using tightly, collimated beams of monoenergetic gamma rays, the measured energy spectra at the gap center show that incomplete charge collection is significant in our detector at 356 and 662 keV, resulting in degradation of the photopeak efficiency. Additionally, close interactions are identifiable in the spectra. Thus, close interactions must be identified on an event-by-event basis in order to precisely identify gap interaction position or make charge-loss corrections at these energies. Furthermore, spectral differences are observed between anode and cathode gaps, and a possible reason for this asymmetry is proposed

Characterization and Calibration of Large Area Resistive Strip Micromegas Detectors

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00389527; The ATLAS collaboration

2016-01-01

Resistive strip Micromegas detectors are discharge tolerant. They have been tested extensively as small detectors of about 10 x 10 cm$^2$ in size and they work reliably at high rates of 100 kHz/cm$^2$ and above. Tracking resolution well below 100 $\\mu$m has been observed for 100 GeV muons and pions. Micromegas detectors are meanwhile proposed as large area muon precision trackers of 2-3 m$^2$ in size. To investigate possible differences between small and large detectors, a 1 m$^2$ detector with 2048 resistive strips at a pitch of 450 $\\mu$m was studied in the LMU Cosmic Ray Measurement Facility (CRMF) using two 4 $\\times$ 2.2 m$^2$ large Monitored Drift Tube (MDT) chambers for cosmic muon reference tracking. A segmentation of the resistive strip anode plane in 57.6 mm x 93 mm large areas has been realized by the readout of 128 strips with one APV25 chip each and by eleven 93 mm broad trigger scintillators placed along the readout strips. This allows for mapping of homogeneity in pulse height and efficiency, d...

Determination of propylthiouracil in pharmaceuticals by differential pulse voltammetry using a cathodically pretreated boron-doped diamond electrode

Energy Technology Data Exchange (ETDEWEB)

Sartori, Elen Romao [Universidade Estadual de Londrina, PR (Brazil). Dept. de Quimica; Trench, Aline Barrios; Rocha-Filho, Romeu C.; Fatibello-Filho, Orlando, E-mail: bello@ufscar.br [Universidade Federal de Sao Carlos (UFSCAR), SP (Brazil). Dept. de Quimica

2013-09-15

A simple procedure is described for the determination of propylthiouracil (PTU) by differential pulse voltammetry (DPV) using a cathodically pretreated boron-doped diamond (BDD) electrode. Cyclic voltammetry studies indicate that the oxidation of PTU is irreversible at a peak potential of 1.42 V (vs. Ag/AgCl (3.0 mol L{sup -1} KCl)) in a Britton-Robinson (BR) buffer solution (pH 2.0). Under optimized conditions, the obtained analytical curve was linear (r = 0.9985) for the PTU concentration range of 1.0 to 29.1 {mu}mol L{sup -1} in a BR buffer solution (pH 2.0), with a detection limit of 0.90 {mu}mol L{sup -1}. The proposed method was successfully applied in the determination of PTU in pharmaceutical samples, with results in agreement at a 95% confidence level with those obtained using an official titration method. (author)

Emission characteristics of dispenser cathodes with a fine-grained tungsten top layer

Science.gov (United States)

Kimura, S.; Higuchi, T.; Ouchi, Y.; Uda, E.; Nakamura, O.; Sudo, T.; Koyama, K.

1997-02-01

In order to improve the emission stability of the Ir-coated dispenser cathode under ion bombardment, a fine-grained tungsten top layer was applied on the substrate porous tungsten plug before Ir coating. The emission characteristics were studied after being assembled in a CRT gun. Cathode current was measured under pulse operation in a range of 0.1-9% duty. Remarkable anti-ion bombardment characteristics were observed over the range of 1-6% duty. The improved cathode showed 1.5 times higher emission current than that of a conventional Ir-coated dispenser cathode at 4% duty. AES analysis showed that the recovering rates of surface Ba and O atoms after ion bombardment were 2.5 times higher. From these results it is confirmed that the Ir coated cathode with a fine-grained tungsten top layer is provided with a good tolerance against the ion bombardment.

Explosive-Emission Plasma Dynamics in Ion Diode in Double-Pulse Mode

International Nuclear Information System (INIS)

Pushkarev, Alexander I.; Isakova, Yulia I.

2011-01-01

The results of an experimental investigation of explosive-emission plasma dynamics in an ion diode with self-magnetic insulation are presented. The investigations were accomplished at the TEMP-4M accelerator set in a mode of double pulse formation. Plasma behaviour in the anode-cathode gap was analyzed according to both the current-voltage characteristics of the diode (time resolution of 0.5 ns) and thermal imprints on a target (spatial resolution of 0.8 mm). It was shown that when plasma formation at the potential electrode was complete, and up until the second (positive) pulse, the explosive-emission plasma expanded across the anode-cathode gap with a speed of 1.3±0.2 cm/μs. After the voltage polarity at the potential electrode was reversed (second pulse), the plasma erosion in the anode-cathode gap (similar to the effect of a plasma opening switch) occurred. During the generation of an ion beam the size of the anode-cathode gap spacing was determined by the thickness of the plasma layer on the potential electrode and the layer thickness of the electrons drifting along the grounded electrode. (15th asian conference on electrical discharge)

Measurement of high-power microwave pulse under intense ...

Indian Academy of Sciences (India)

Abstract. KALI-1000 pulse power system has been used to generate single pulse nanosecond duration high-power microwaves (HPM) from a virtual cathode oscillator. (VIRCATOR) device. HPM power measurements were carried out using a transmitting– receiving system in the presence of intense high frequency (a few ...

Amplification of the dd reaction and X radiation generation in a high-current pulse glow discharge in deuterium with the Ti cathode at 0.8-2.45 kV

International Nuclear Information System (INIS)

Lipson, A.G.; Rusetskij, A.S.; Karabut, A.B.; Majli, Dzh.

2005-01-01

The dd-reaction yield (3 MeV protons) and the soft X-ray emission from a titanium cathode surface in a periodic pulsed glow discharge in deuterium were studied. The deuteron screening potential was estimated from analysis of the dd-reaction yield as a function of the accelerating voltage. The obtained data show evidence for a significant enhancement of the dd-reaction yield in Ti in comparison to both theoretical estimates and the results of experiments using accelerators at the deuteron energies ≥ 2.5 keV. Intense emission of soft X-ray quanta was observed. The X-ray emission intensity and the dd-reaction yield enhancement strongly depend on the rate of deuterium diffusion in a thin subsurface layer of Ti cathode [ru

Studies of ageing effects of Small-Strip Thin Gap Chambers for the Muon Spectrometer Upgrade of the ATLAS Experiment

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00425540; The ATLAS collaboration

2016-01-01

The instantaneous luminosity of the Large Hadron Collider at CERN will be increased by up to seven times its design value by undergoing an extensive upgrade program over the coming decade. The largest upgrade project for the ATLAS Muon System is the replacement of the present first station in the forward regions with the so-called New Small Wheels (NSWs), to be installed during the LHC long shutdown in 2019-2020. Small-Strip Thin Gap Chambers (sTGC) detectors are one chosen technology to provide fast trigger and high precision muon tracking under the high luminosity LHC conditions. The basic sTGC structure consists of a grid of gold-plated tungsten wires sandwiched between two resistive cathode planes at a small distance from the wire plane. We study ageing effects of sTGC detectors with a gas mixture of 55\\% of CO$_{2}$ and 45\\% of n-pentane. A sTGC detector was irradiated with beta-rays from a 10~mCi~$^{90}$Sr source. Three different gas flow rates were tested. We observed no deterioration on pulse height o...

Studies of ageing effects of Small-Strip Thin Gap Chambers for the Muon Spectrometer Upgrade of the ATLAS Experiment

CERN Document Server

Gignac, Matthew; The ATLAS collaboration

2016-01-01

The instantaneous luminosity of the Large Hadron Collider at CERN will be increased up to a factor of five with respect to the design value by undergoing an extensive upgrade program over the coming decade. The largest upgrade project for the ATLAS Muon System is the replacement of the present first station in the forward regions with the so-called New Small Wheels (NSWs), to be installed during the LHC long shutdown in 2019/20. Small-Strip Thin Gap Chambers (sTGC) detectors are one chosen technology to provide fast trigger and high precision muon tracking under the high luminosity LHC conditions. The basic sTGC structure consists of a grid of gold-plated tungsten wires sandwiched between two resistive cathode planes at a small distance from the wire plane. We study ageing effects of sTGC detectors with a gas mixture of 55% of CO_2 and 45% of n-pentane. A sTGC detector was irradiated with beta-rays from a Sr-90 source. Three different gas flow rates were tested. We observed no deterioration on pulse height of...

The effect of cathode surface impurities on gap closure

International Nuclear Information System (INIS)

Hinshelwood, D.D.

1983-01-01

Gap closure due to cathode (or anode) plasma motion is often the principal limitation on the pulse length of intense beam diodes and magnetically insulated transmission lines. Since the plasma expansion velocity is typically on the order of the sound speed, a high atomic number plasma is desirable. In recent experiments performed on a Sandia Nereus accelerator (240kV, 50kA, 3-30kA/cm 2 , 70ns) with a parallel plate diode, the cathode plasma was seen to be composed of both the cathode substrate material and constituents (hydrogen and carbon) of surface contaminants such as pump oils. The plasma expansion velocities, inferred from impedance measurements, were 1.5-2 cm/μs and were the same for carbon, aluminum and stainless steel cathodes. This similarity, combined with the temperature estimates of 2-3eV obtained from spectroscopy, implied that the expansion was due to protons from surface contaminants. Similar results were reported from studies of ablatively driven plasmas. In a continuation of the work, the results of time and spatially resolved spectroscopic studies of plasma formed on aluminum cathodes, yielding measurements of the expansion velocities of different components of the cathode plasma, are presented. We have heated stainless steel cathodes in situ to 700 0 C. The Hα line emission was seen to decrease by more than an order of magnitude (becoming lost in the background) when the cathodes were heated but no change in the impedance behavior was observed. Evidently the heating was insufficient to remove the last monolayer, which should contain more than enough hydrogen to close the gap. Preliminary experiments with gold-plated cathodes (which should be more resistant to chemisorption) yielded similar results. Further measurements of plasma formed on heated cathodes are presented

Study on the cathode of ion source for neutral beam injector

International Nuclear Information System (INIS)

Tanaka, Shigeru

1983-08-01

Durability of the cathode is an important problem in developing a high power long pulse ion source for neutral beam injector. The Purpose of this study is to develope a long life cathode and investigate the applicability of it to the source. Directly heated filaments which are commonly used as the cathode of injector source do not live very long in general. In the present work, an indirectly heated hollow cathode made of impregnated porous tungsten tube is proposed as the alternative of the directly heated cathode. At first, we fabricated a small hollow cathode to study the discharge characteristcs in a bell-jar configuration and to apply it to a duoPIGatron hydrogen ion source. The experiment showed that the gas flow rate for sustaining the stable arc discharge in the discharge chamber becomes higher than that when the filament cathode is used. To solve this problem, an experiment for gas reduction was made using a newly fabricated larger hollow cathode and a magnetic multi-pole ion source. The influence of the orifice diameter, the effect of a button and of magnetic field on the gas flow rate were experimentally studied and a method for gas reduction was found. In addition, effect of the magnetic field on the characteristics of the hollow cathode ion source was examined in detail and an optimum field configuration around the cathode was found. Finally, beam extraction from an intensively cooled hollow cathode ion source for up to 10 sec was successfully carried out. (author)

Cathodic adsorptive stripping voltammetric determination of Ribavirin in pharmaceutical dosage form, urine and serum

Directory of Open Access Journals (Sweden)

Ahmed A. Abdel Gaber

2017-05-01

Full Text Available A sensitive, simple and rapid square-wave adsorptive stripping voltammetric method was developed and validated for the determination of Ribavirin in pharmaceutical formulations. The proposed method was based on the electrochemical reduction of Ribavirin at a hanging mercury drop electrode in Britton Robinson buffer at pH 10. A well-defined peak was observed at 880 mV with 30 s of accumulation time and 50 mV of accumulation potential. Under these optimized conditions, the square-wave adsorptive stripping voltammetric peak current showed a linear correlation on drug concentration over the range of 1 × 10−10–2 × 10−7 mol L−1 with a correlation coefficient of 0.9995 for the proposed method. The detection and quantitation limits for this method were 2.02 × 10−10 and 6.80 × 10−10 mol L−1, respectively. The results obtained for intra-day and inter-day precision (as RSD % were between 0.447% and 1.024%. This method was applied successfully for the determination of Ribavirin in its pharmaceutical dosage forms with mean recoveries of 99.68 ± 0.13 with RSD % of 0.81% and 99.20 ± 0.24 with RSD % of 0.49% for two concentrations 5 × 10−9 and 5 × 10−8 mol L−1, respectively for 200 mg capsules. The results obtained from the developed square-wave adsorptive stripping voltammetric method were compared with those obtained by the analytical method reported in the literature.

Gas proportional detectors with interpolating cathode pad readout for high track multiplicities

International Nuclear Information System (INIS)

Yu, Bo.

1991-12-01

New techniques for position encoding in very high rate particle and photon detectors will be required in experiments planned for future particle accelerators such as the Superconducting Super Collider and new, high intensity, synchrotron sources. Studies of two interpolating cathode ''pad'' readout systems are described in this thesis. They are well suited for high multiplicity, two dimensional unambiguous position sensitive detection of minimum ionizing particles and heavy ions as well as detection of x-rays at high counting rates. One of the readout systems uses subdivided rows of pads interconnected by resistive strips as the cathode of a multiwire proportional chamber (MWPC). A position resolution of less than 100 μm rms, for 5.4 keV x-rays, and differential non-linearity of 12% have been achieved. Low mass (∼0.6% of a radiation length) detector construction techniques have been developed. The second readout system uses rows of chevron shaped cathode pads to perform geometrical charge division. Position resolution (FWHM) of about 1% of the readout spacing and differential non-linearity of 10% for 5.4 keV x-rays have been achieved. A review of other interpolating methods is included. Low mass cathode construction techniques are described. In conclusion, applications and future developments are discussed. 54 refs

Growth feature of ionic nitrogen doped CN_x bilayer films with Ti and TiN interlayer by pulse cathode arc discharge

International Nuclear Information System (INIS)

Zhou, Bing; Liu, Zhubo; Piliptsou, D.G.; Rogachev, A.V.; Yu, Shengwang; Wu, Yanxia; Tang, Bin; Rudenkov, A.S.

2016-01-01

Graphical abstract: - Highlights: • Ti/ and TiN/CN_x (N"+) bilayers are prepared at various frequencies by pulse cathode arc. • Ti interlayer facilitates the introduction of N atoms into the CN_x (N"+) films. • The most N-sp"2C bonds (mainly graphite-like N) present in the TiN/CN_x (N"+, 3 Hz) film. • Ti/CN_x (N"+, 3 Hz) bilayer possesses small size and disordering of Csp"2 clusters. • The higher hardness and the lower stress presents in the TiN/CN_x (N"+, 10 Hz) bilayer. - Abstract: Using nano-scaled Ti and TiN as interlayer, ionic nitrogen doped carbon (CN_x (N"+)) bilayer films were prepared at various pulse frequencies by cathode arc technique. Elemental distribution at the interface, bonding compositions, microstructure, and mechanical properties of CN_x (N"+) bilayer films were investigated in dependence of interlayer and pulse frequency by Auger electron spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, nanoindentation, and surface profilometer. The results showed that the diffusion extent of C atoms at the interface of CN_x (N"+) bilayers is higher than for the α-C and CN_x (N_2) bilayers with the same interlayer. Nitrogen atoms could diffuse throughout the pre-deposited Ti and TiN layers into the Si substrate for all CN_x (N"+) bilayers. Ti interlayer facilitates the introduction of N atoms into the CN_x (N"+) films and exhibits a certain catalytic effect on the coordination of N atoms with sp"2- and sp"3-C binding. More nitrogenated and intense CN bonding configurations (mainly graphite-like N) form in the TiN/CN_x (N"+) bilayer. Ti/CN_x (N"+) bilayer prepared at low frequency possesses small size and disordering of Csp"2 clusters but TiN interlayer weakens the formation of Csp"2 bonding and increases the disordering of Csp"2 clusters in the films. The residual stress in the bilayer is lower than for CN_x (N"+) monolayer. The higher hardness and the lower residual stress are present in the TiN/CN_x (N"+, 10 Hz) bilayer.

Advancements of floating strip Micromegas detectors for medical imaging applications

Energy Technology Data Exchange (ETDEWEB)

Klitzner, Felix; Biebel, Otmar; Bortfeldt, Jonathan; Flierl, Bernhard [LS Schaile, LMU Muenchen (Germany); Magallanes, Lorena [LS Parodi, LMU Muenchen (Germany); Universitaetsklinikum Heidelberg (Germany); Parodi, Katia [LS Parodi, LMU Muenchen (Germany); Heidelberger Ionenstrahl Therapiezentrum (Germany); Voss, Bernd [Gesellschaft fuer Schwerionenforschung, Darmstadt (Germany)

2016-07-01

Floating strip Micromegas have proven to be high-rate capable tracking detectors with excellent spatial and temporal resolution for particle fluxes up to 7 MHz/cm{sup 2}. To further increase the high-rate capability a Ne:CF{sub 4} 86:14 vol.% gas mixture has been used as detector gas. We present results from measurements with a seven detector system consisting of six low material budget floating strip Micromegas, a GEM detector and a scintillator based particle range telescope. The gaseous and the scintillation detectors were read out with APV25 frontend boards, allowing for single strip readout with pulse height and timing information. A two-dimensional readout anode for floating strip Micromegas has been tested for the first time. The Micromegas detectors were operated with minimal additional drift field, which significantly improves the timing resolution and also the spatial resolution for inclined tracks. We discuss the detector performance in high-rate carbon and proton beams at the Heidelberg Ion Beam Therapy Center (HIT) and present radiographies of phantoms, acquired with the system.

Electrochemical performance of polypyrrole/silver vanadium oxide composite cathodes in lithium primary batteries

Science.gov (United States)

Anguchamy, Yogesh K.; Lee, Jong-Won; Popov, Branko N.

Polypyrrole (PPy)/silver vanadium oxide (SVO) composite cathode materials were synthesized by polymerizing pyrrole onto the surface of pure SVO particles. Electrochemical characterization was carried out by performing galvanostatic discharge, pulse discharge and ac-impedance experiments. The composite electrode exhibited better performance than pristine SVO in all the experiments. The composite electrodes yielded a higher discharge capacity and a better pulse discharge capability when compared to the pristine SVO electrode. The pulse discharge and ac-impedance studies indicated that PPy forms an effective conductive network on the SVO surface and thereby reduces the particle-to-particle contact resistance and facilitates the interfacial charge transfer kinetics. To determine the thermal stability of the composite cathode, galvanostatic discharge and ac-impedance experiments were performed at different temperatures. The capacity increased with temperature due to enhanced charge transfer kinetics and low mass transfer limitations. The peak capacity was obtained at 60 °C, after which the performance degraded with any further increase in temperature.

Electrochemical performance of polypyrrole/silver vanadium oxide composite cathodes in lithium primary batteries

Energy Technology Data Exchange (ETDEWEB)

Anguchamy, Yogesh K.; Lee, Jong-Won; Popov, Branko N. [Center for Electrochemical Engineering, Department of Chemical Engineering, University of South Carolina, Columbia, SC 29208 (United States)

2008-09-15

Polypyrrole (PPy)/silver vanadium oxide (SVO) composite cathode materials were synthesized by polymerizing pyrrole onto the surface of pure SVO particles. Electrochemical characterization was carried out by performing galvanostatic discharge, pulse discharge and ac-impedance experiments. The composite electrode exhibited better performance than pristine SVO in all the experiments. The composite electrodes yielded a higher discharge capacity and a better pulse discharge capability when compared to the pristine SVO electrode. The pulse discharge and ac-impedance studies indicated that PPy forms an effective conductive network on the SVO surface and thereby reduces the particle-to-particle contact resistance and facilitates the interfacial charge transfer kinetics. To determine the thermal stability of the composite cathode, galvanostatic discharge and ac-impedance experiments were performed at different temperatures. The capacity increased with temperature due to enhanced charge transfer kinetics and low mass transfer limitations. The peak capacity was obtained at 60 C, after which the performance degraded with any further increase in temperature. (author)

Improvements in or relating to methods of and apparatus for coating wire, rod or strip material by sputtering

International Nuclear Information System (INIS)

Wareing, J.B.

1976-01-01

A method and apparatus are described for coating wire, rod or strip material comprising first subjecting the material to electron bombardment in a glow discharge to heat and activate the surface and then subjecting it to sputtering by use of a soft cathode discharge. The apparatus comprises a low pressure gas chamber through which the material is passed, and containing a glow discharge electron gun having a tubular cathode shaped so that the material can be passed axially through it, and an anode surrounding the cathode. The cathode is formed in two parts, the first part at one end, being made of material of low sputtering yield, and the second part being formed at least partially of the required coating material. The first part of the cathode may be of stainless steel or Al. The two parts of the cathode are electrically isolated with means provided for applying a lower negative potential, with respect to the anode, to the second part compared with the first part. The voltage applied to the second part may be controlled so as to control the sputtering rate. The gas pressure in the chamber is also controllable. The coating material may be arranged as inserts in the fixed cathode structure or as segments around the surface to be coated, and may be composed of Pb, Zn or Cu. (U.K.)

A pulsed electron gun for the Plane Wave Transformer Linac

Science.gov (United States)

Mahadevan, S.; Gandhi, M. L.; Nandedkar, R. V.

2003-01-01

A pulsed diode electron gun delivering 500 mA current at 40 kV is described. The gun geometry is optimized using the Electron Trajectory Program EGUN at higher scaling factors by choosing the closest converging starting surface. The effect of an annular gap between cathode and focusing electrode on beam behaviour is compensated by using a suitable focusing electrode. The estimated perveance is 0.065 μperv and the normalized emittance is within 5 π mm mrad. The variation in current density at the cathode has been limited to within 10% across the face of the cathode. Salient features of the pulsed power supply and an insight of its interconnection with the gun are presented. The current measured at the Faraday cup is in agreement with the designed perveance.

A pulsed electron gun for the Plane Wave Transformer Linac

Energy Technology Data Exchange (ETDEWEB)

Mahadevan, S. E-mail: maharaja@cat.ernet.in; Gandhi, M.L. E-mail: mlg@cat.ernet.in; Nandedkar, R.V. E-mail: nrv@cat.ernet.in

2003-01-01

A pulsed diode electron gun delivering 500 mA current at 40 kV is described. The gun geometry is optimized using the Electron Trajectory Program EGUN at higher scaling factors by choosing the closest converging starting surface. The effect of an annular gap between cathode and focusing electrode on beam behaviour is compensated by using a suitable focusing electrode. The estimated perveance is 0.065 {mu}perv and the normalized emittance is within 5{pi} mm mrad. The variation in current density at the cathode has been limited to within 10% across the face of the cathode. Salient features of the pulsed power supply and an insight of its interconnection with the gun are presented. The current measured at the Faraday cup is in agreement with the designed perveance.

A pulsed electron gun for the Plane Wave Transformer Linac

CERN Document Server

Mahadevan, S; Nandedkar, R V

2003-01-01

A pulsed diode electron gun delivering 500 mA current at 40 kV is described. The gun geometry is optimized using the Electron Trajectory Program EGUN at higher scaling factors by choosing the closest converging starting surface. The effect of an annular gap between cathode and focusing electrode on beam behaviour is compensated by using a suitable focusing electrode. The estimated perveance is 0.065 mu perv and the normalized emittance is within 5 pi mm mrad. The variation in current density at the cathode has been limited to within 10% across the face of the cathode. Salient features of the pulsed power supply and an insight of its interconnection with the gun are presented. The current measured at the Faraday cup is in agreement with the designed perveance.

A pulsed electron gun for the Plane Wave Transformer Linac

International Nuclear Information System (INIS)

Mahadevan, S.; Gandhi, M.L.; Nandedkar, R.V.

2003-01-01

A pulsed diode electron gun delivering 500 mA current at 40 kV is described. The gun geometry is optimized using the Electron Trajectory Program EGUN at higher scaling factors by choosing the closest converging starting surface. The effect of an annular gap between cathode and focusing electrode on beam behaviour is compensated by using a suitable focusing electrode. The estimated perveance is 0.065 μperv and the normalized emittance is within 5π mm mrad. The variation in current density at the cathode has been limited to within 10% across the face of the cathode. Salient features of the pulsed power supply and an insight of its interconnection with the gun are presented. The current measured at the Faraday cup is in agreement with the designed perveance

Ozone formation in pulsed SDBD in a wide pressure range

Science.gov (United States)

Starikovskiy, Andrey; Nudnova, Maryia; mipt Team

2011-10-01

Ozone concentration in surface anode-directed DBD for wide pressure range (150 - 1300 torr) was experimentally measured. Voltage and pressure effect were investigated. Reduced electric field was measured for anode-directed and cathode-directed SDBD. E/n values in cathode-directed SDBD is higher than in cathode-directed on 50 percent at atmospheric pressure. E/n value increase leads to decrease the rate of oxygen dissociation and Ozone formation at lower pressures. Radiating region thickness of sliding discharge was measured. Typical thickness of radiating zone is 0.4-1.0 mm within pressure range 220-740 torr. It was shown that high-voltage pulsed nanosecond discharge due to high E/n value produces less Ozone with compare to other discharges. Kinetic model was proposed to describe Ozone formation in the pulsed nanosecond SDBD.

Acquisition and calibration electronics of a MWPC with a cathodic read-out

Energy Technology Data Exchange (ETDEWEB)

Carbonara, F; Chiefari, G; Drago, E; Ereditato, A; Lanzano, S; Napolitano, M; Sciacca, G [Istituto Nazionale di Fisica Nucleare, Naples (Italy); Naples Univ. (Italy). Ist. di Fisica Sperimentale)

1982-02-01

A periodic calibration of the electronics associated with the cathodic strips of a MWPC is necessary for a correct computation of the centroid of the induced charge. We describe here a method, based on computer controlled analog demultiplexers, which permits the injection of variable amounts of charge into each amplifier. The serial scanning along all the channels produces the complete set of pedestals and slopes which, stored on disk and subsequently read, is used for the conversion of ADC outputs.

PDC: A wire chamber cathode read-out on 6-bit fast ADC

Energy Technology Data Exchange (ETDEWEB)

De Giorgi, M; Gasparini, F; Meneguzzo, A T; Pitacco, G [Istituto Nazionale di Fisica Nucleare, Padua (Italy); Padua Univ. (Italy). Ist. di Fisica)

1984-06-01

A read-out for MWPC and drift chamber is presented in which the coordinate along the sense wires is obtained by measuring the centre of gravity (CoG) of the charge induced on cathode strips or pads. The peak value of the signals coming from subsets of 8-pad cathodes are recorded by a parallel sample and hold, strobed by their own OR, and then serially digitized by one 6-bit fast ADC (FADC). The basic module of the system is a peak detector and converter (PDC) built in CAMAC cards, which could be an interesting approach to the analog signal acquisition of large particle detectors. The system has been designed to equip the central detector in an experiment at the CERN LEAR facility. A prototype of a card will be described and the results of some tests will be presented.

Multi-kiloampere, electron-beam generation using metal photo-cathodes driven by ArF and KrF lasers

Energy Technology Data Exchange (ETDEWEB)

Carlson, R L; Moya, S S; Ridlon, R N; Seitz, G J; Shurter, R P [Los Alamos Natl. Lab., Los Alamos, NM (United States)

1997-12-31

An electron-beam-pumped laser operating at ArF (193 nm) or KrF (248 nm) producing 35 MW (3.5 J in 100 ns) has been used to illuminate a micro-machined aluminum cathode. The cathode was pulsed to 2.75 MV at fields of 185 kV/cm (15-cm AK gap) using REX (a 4-MV, 5-kA, 85-ns) pulsed-diode machine. The extracted current versus incident laser power (the quantum efficiency) was measured for KrF at 5x10{sup -5} and for ArF which was significantly higher at 1x10{sup -3}. Current densities of 100 A/cm{sup 2} and total currents of 2 kA have been achieved, the latter by increasing the cathode area in proportion to the laser power. (author). 8 figs., 14 refs.

Small compact pulsed electron source for radiation technologies

International Nuclear Information System (INIS)

Korenev, Sergey

2002-01-01

The small compact pulsed electron source for radiation technologies is considered in the report. The electron source consists of pulsed high voltage Marx generator and vacuum diode with explosive emission cathode. The main parameters of electron source are next: kinetic energy is 100-150 keV, beam current is 5-200 A and pulse duration is 100-400 nsec. The distribution of absorbed doses in irradiated materials is considered. The physical feasibility of pulsed low energy electron beam for applications is considered

Back bombardment for dispenser and lanthanum hexaboride cathodes

Directory of Open Access Journals (Sweden)

Mahmoud Bakr

2011-06-01

Full Text Available The back bombardment (BB effect limits wide usage of thermionic rf guns. The BB effect induces not only ramping-up of a cathode’s temperature and beam current, but also degradation of cavity voltage and beam energy during a macropulse. This paper presents a comparison of the BB effect for the case of dispenser tungsten-base (DC and lanthanum hexaboride (LaB_{6} thermionic rf gun cathodes. For each, particle simulation codes are used to simulate the BB effect and electron beam dynamics in a thermionic rf gun cathode. A semiempirical equation is also used to investigate the stopping range and deposited heat power of BB electrons in the cathode material. A numerical simulation method is used to calculate the change of the cathode temperature and current density during a single macropulse. This is done by solving two differential equations for the rf gun cavity equivalent circuit and one-dimensional thermal diffusion equation. High electron emission and small beam size are required for generation of a high-brightness electron beam, and so in this work the emission properties of the cathode are taken into account. Simulations of the BB effect show that, for a pulse of 6  μs duration, the DC cathode experiences a large change in the temperature compared with LaB_{6}, and a change in current density 6 times higher. Validation of the simulation results is performed using experimental data for beam current beyond the gun exit. The experimental data is well reproduced using the simulation method.

Mechanism for negative corona current pulse in CO sub 2 -SF sub 6 mixtures

CERN Document Server

Zahoranova, A; Simor, M; Cernak, M

2003-01-01

Current waveforms of first negative corona pulses have been measured in CO sub 2 -SF sub 6 mixtures over a pressure range extending from 6.65 to 50 kPa and various overvoltages. Effects of changing cathode secondary electron emission were studied using a copper cathode coated by CuI and graphite. For a given set of experimental conditions it is concluded that in the mixtures containing up to 30% of SF sub 6 the negative corona pulse is associated with the formation of a cathode-directed streamer-like ionizing wave in the immediate vicinity of the cathode. This is in contrast to the discharge behaviour in air-SF sub 6 and N sub 2 -SF sub 6 mixtures, where in similar conditions the discharge develops according to a multi-avalanche Townsend mechanism. (rapid communication)

Dispersion - does it degrade a pulse envelope

International Nuclear Information System (INIS)

Deighton, M.O.

1985-01-01

In hostile environments, transmitting information as ultrasonic Lamb wave pulses has advantages, since the stainless steel strip serving as a waveguide is very durable. Besides attenuation, velocity dispersion (inherent in Lamb waves) can be important even in fairly short guides. Theory shows that unlimited propagation of a pulsed r.f. envelope is possible, even with dispersion present. The constant group velocity needed would favour asub(o)-mode pulses over other modes, provided ordinary attenuation is small. An approximate formula indicates the useful range of a pulse, when group velocity does vary. (author)

Electric field induced needle-pulsed arc discharge carbon nanotube production apparatus: Circuitry and mechanical design

Energy Technology Data Exchange (ETDEWEB)

Kia, Kaveh Kazemi [Department of Electrical and Computer Engineering, Islamic Azad University of Bonab, Bonab (Iran, Islamic Republic of); Bonabi, Fahimeh [Department of Engineering, Islamic Azad University of Bonab, Bonab (Iran, Islamic Republic of)

2012-12-15

A simple and low cost apparatus is reported to produce multiwall carbon nanotubes and carbon nano-onions by a low power short pulsed arc discharge reactor. The electric circuitry and the mechanical design details and a micro-filtering assembly are described. The pulsed-plasma is generated and applied between two graphite electrodes. The pulse width is 0.3 {mu}s. A strong dc electric field is established along side the electrodes. The repetitive discharges occur in less than 1 mm distance between a sharp tip graphite rod as anode, and a tubular graphite as cathode. A hydrocarbon vapor, as carbon source, is introduced through the graphite nozzle in the cathode assembly. The pressure of the chamber is controlled by a vacuum pump. A magnetic field, perpendicular to the plasma path, is provided. The results show that the synergetic use of a pulsed-current and a dc power supply enables us to synthesize carbon nanoparticles with short pulsed plasma. The simplicity and inexpensiveness of this plan is noticeable. Pulsed nature of plasma provides some extra degrees of freedom that make the production more controllable. Effects of some design parameters such as electric field, pulse frequency, and cathode shape are discussed. The products are examined using scanning probe microscopy techniques.

Electric field induced needle-pulsed arc discharge carbon nanotube production apparatus: circuitry and mechanical design.

Science.gov (United States)

Kia, Kaveh Kazemi; Bonabi, Fahimeh

2012-12-01

A simple and low cost apparatus is reported to produce multiwall carbon nanotubes and carbon nano-onions by a low power short pulsed arc discharge reactor. The electric circuitry and the mechanical design details and a micro-filtering assembly are described. The pulsed-plasma is generated and applied between two graphite electrodes. The pulse width is 0.3 μs. A strong dc electric field is established along side the electrodes. The repetitive discharges occur in less than 1 mm distance between a sharp tip graphite rod as anode, and a tubular graphite as cathode. A hydrocarbon vapor, as carbon source, is introduced through the graphite nozzle in the cathode assembly. The pressure of the chamber is controlled by a vacuum pump. A magnetic field, perpendicular to the plasma path, is provided. The results show that the synergetic use of a pulsed-current and a dc power supply enables us to synthesize carbon nanoparticles with short pulsed plasma. The simplicity and inexpensiveness of this plan is noticeable. Pulsed nature of plasma provides some extra degrees of freedom that make the production more controllable. Effects of some design parameters such as electric field, pulse frequency, and cathode shape are discussed. The products are examined using scanning probe microscopy techniques.

[Atomic/ionic fluorescence in microwave plasma torch discharge excited by high current microsecond pulsed hollow cathode lamp-europium atomic/ionic fluorescence spectrometry].

Science.gov (United States)

Gong, Z; Liang, F; Yang, P; Jin, Q; Huang, B

1999-06-01

Eu atomic and ionic fluorescence spectrometry in microwave plasma torch discharge excited by high current microsecond pulsed hollow cathode lamp (HCMP HCL-MPT AFS/IFS) was studied. Operating conditions were optimized. The best detection limits for AFS and IFS obtained with a desolvated ultrasonic nebulization system were 42.0 ng/mL for Eu I 462.7 nm and 21.8 ng/mL for Eu II 381.97 nm, respectively, both were better than those given by the instruction manual of a Baird ICP AFS-2000 spectrometer using pneumatic concentric nebulizer with desolvation for AFS, but were significantly higher than those obtained by using the Baird spectrometer with a mini-monochromator and a ultrasonic nebulzer system.

Influence of the radial spacing between cathodes on the surface composition of iron samples sintered by hollow cathode electric discharge

Directory of Open Access Journals (Sweden)

Brunatto S.F.

2001-01-01

Full Text Available The present work reports an investigation of the influence of the radial spacing between cathodes on the iron sintering process by hollow cathode electrical discharge, with surface enrichment of the alloying elements Cr and Ni. Pressed cylindrical samples of 9.5 mm diameter and density of 7.0 ± 0.1 g/cm³ were prepared by compaction of Ancorsteel 1000C iron powder. These samples, constituting the central cathode, were positioned concentrically in the interior of an external cathode machined from a tube of stainless steel AISI 310 (containing: 25% Cr, 16% Ni, 1.5% Mn, 1.5% Si, 0.03% C and the remainder Fe. Sintering was done at 1150 °C, for 120 min, utilizing radial spacings between the central and hollow cathodes of 3, 6 and 9 mm and a gas mixture of 80% Ar and 20% H2, with a flow rate of 5 cm³/s at a pressure of 3 Torr. The electric discharge was generated using a pulsed voltage power source, with a period of 200 mus. The radial spacing had only a slight influence on the quantity of atoms of alloying elements deposited and diffused on the surface of the sample. Analysis with a microprobe showed the presence of chrome (up to 4.0% and nickel (up to 3.0%, in at. % at the surface of the samples. This surface enrichment can be attributed to the mechanism of sputtering of the metallic atoms present in the external cathode, with the deposition of these elements on the sample surface and consequent diffusion within the sample.

Operation of cold-cathode gauges in high magnetic fields

International Nuclear Information System (INIS)

Thomas, S.R. Jr.; Goerz, D.A.; Pickles, W.L.

1985-01-01

The Mirror Fusion Test Facility (MFTF-B), under construction at LLNL, requires measurement of the neutral gas density in high magnetic fields near the plasma at several axial regions. This Background Gas Pressure (BGP) diagnostic will help us understand the role of background neutrals in particle and power balance, particularly in the maintenance of the cold halo plasma that shields the hot core plasma from the returning neutrals. It consists of several cold-cathode, magnetron-type gauges stripped of their permanent magnets, and utilizes the MFTF-B ambient B-field in strengths of 5 to 25 kG. Similar gauges have operated in TMX-U in B-fields up to 3 kG. To determine how well the gauges will perform, we assembled a test stand which operated magnetron gauges in an external, uniform magnetic field of up to 30 kG, over a pressure range of 1E-8 T to 1E-5 T, at several cathode voltages. This paper describes the test stand and presents the results of the tests

The study of Zn–Co alloy coatings electrochemically deposited by pulse current

Directory of Open Access Journals (Sweden)

Tomić Milorad V.

2012-01-01

Full Text Available The electrochemical deposition by pulse current of Zn-Co alloy coatings on steel was examined, with the aim to find out whether pulse plating could produce alloys that could offer a better corrosion protection. The influence of on-time and the average current density on the cathodic current efficiency, coating morphology, surface roughness and corrosion stability in 3% NaCl was examined. At the same Ton/Toff ratio the current efficiency was insignificantly smaller for deposition at higher average current density. It was shown that, depending on the on-time, pulse plating could produce more homogenous alloy coatings with finer morphology, as compared to deposits obtained by direct current. The surface roughness was the greatest for Zn-Co alloy coatings deposited with direct current, as compared with alloy coatings deposited with pulse current, for both examined average current densities. It was also shown that Zn-Co alloy coatings deposited by pulse current could increase the corrosion stability of Zn-Co alloy coatings on steel. Namely, alloy coatings deposited with pulse current showed higher corrosion stability, as compared with alloy coatings deposited with direct current, for almost all examined cathodic times, Ton. Alloy coatings deposited at higher average current density showed greater corrosion stability as compared with coatings deposited by pulse current at smaller average current density. It was shown that deposits obtained with pulse current and cathodic time of 10 ms had the poorest corrosion stability, for both investigated average deposition current density. Among all investigated alloy coatings the highest corrosion stability was obtained for Zn-Co alloy coatings deposited with pulsed current at higher average current density (jav = 4 A dm-2.

Pulsed lower-hybrid wave penetration in reactor plasmas

International Nuclear Information System (INIS)

Cohen, R.H.; Bonoli, P.T.; Porkolab, M.; Rognlien, T.D.

1989-01-01

Providing lower-hybrid power in short, intense (GW) pulses allows enhanced wave penetration in reactor-grade plasmas. We examine nonlinear absorption, ray propagation, and parametric instability of the intense pulses. We find that simultaneously achieving good penetration while avoiding parametric instabilities is possible, but imposes restrictions on the peak power density, pulse duration, and/or r.f. spot shape. In particular, power launched in narrow strips, elongated along the field direction, is desired

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.

Design and fabrication of a pulsed diode electron gun

International Nuclear Information System (INIS)

Mahadevan, S.; Gandhi, M.L.; Nandedkar, R.V.

2003-01-01

A pulsed diode electron gun has been designed, fabricated and tested and this will be used for the initial hot testing of the Plane Wave Transformer (PWT) linac. The gun is required to deliver 1 A at 70 kV which works out to a current of 500 mA at 40 kV. The gun geometry is optimized using the Electron Trajectory Program EGUN at a mesh size of 0.2 mm. The beam divergence close to cathode caused by an annular gap of 2 mm between cathode and focusing electrode (FE) is compensated by using a suitable focusing electrode. Important features of the pulsed power supply (40 kV, 500 mA, 2 μsec) developed for testing this gun are presented. The current measured at the Faraday cup is in agreement with the designed perveance. Suitable positioning of cathode with respect to the FE helps in further improving the beam quality

Pulsed neutron source well logging system

International Nuclear Information System (INIS)

Dillingham, M.E.

1975-01-01

A pulsed neutron source arrangement is provided in which a sealed cylindrical chamber encloses a rotatable rotor member carrying a plurality of elongated target strips of material which emits neutrons when bombarded with alpha particles emitted by the plurality of source material strips. The rotor may be locked in a so-called ON position by an electromagnetic clutch drive mechanism controllable from the earth's surface so as to permit the making of various types of logs utilizing a continuously emitting neutron source. (Patent Office Record)

Ecton processes in the generation of pulsed runaway electron beams in a gas discharge

Science.gov (United States)

Mesyats, G. A.

2017-09-01

As was shown earlier for pulsed discharges that occur in electric fields rising with extremely high rates (1018 V/(cm s)) during the pulse rise time, the electron current in a vacuum discharge is lower than the current of runaway electrons in an atmospheric air discharge in a 1-cm-long gap. In this paper, this is explained by that the field emission current from cathode microprotrusions in a gas discharge is enhanced due to gas ionization. This hastens the initiation of explosive electron emission, which occurs within 10-11 s at a current density of up to 1010 A/cm2. Thereafter, a first-type cathode spot starts forming. The temperature of the cathode spot decreases due to heat conduction, and the explosive emission current ceases. Thus, the runaway electron current pulse is similar in nature to the ecton phenomenon in a vacuum discharge.

Thermophysical properties by a pulse-heating reflectometric technique: Niobium, 1100 to 2700 K

International Nuclear Information System (INIS)

Righini, F.; Spisiak, J.; Bussolino, G.C.; Gualano, M.

1999-01-01

Pulse heating experiments were performed on niobium strips, taking the specimens from room temperature to the melting point is less than one second. The normal spectral emissivity of the strips was measured by integrating sphere reflectometry, and, simultaneously, experimental data (radiance temperature, current, voltage drop) for thermophysical properties were collected with submillisecond time resolution. The normal spectral emissivity results were used to compute the true temperature of the niobium strips; the heat capacity, electrical resistivity, and hemispherical total emissivity were evaluated in the temperature range 1,100 to 2,700 K. The results are compared with literature data obtained in pulse-heating experiments. It is concluded that combined measurements of normal spectral emissivity and of thermophysical properties on strip specimens provide results of the same quality as obtained using tubular specimens with a blackbody. The thermophysical property results on niobium also validate the normal spectral emissivity measurements by integrating sphere reflectometry

Plasma parameters of the cathode spot explosive electron emission cell obtained from the model of liquid-metal jet tearing and electrical explosion

Science.gov (United States)

Tsventoukh, M. M.

2018-05-01

A model has been developed for the explosive electron emission cell pulse of a vacuum discharge cathode spot that describes the ignition and extinction of the explosive pulse. The pulse is initiated due to hydrodynamic tearing of a liquid-metal jet which propagates from the preceding cell crater boundary and draws the ion current from the plasma produced by the preceding explosion. Once the jet neck has been resistively heated to a critical temperature (˜1 eV), the plasma starts expanding and decreasing in density, which corresponds to the extinction phase. Numerical and analytical solutions have been obtained that describe both the time behavior of the pulse plasma parameters and their average values. For the cell plasma, the momentum per transferred charge has been estimated to be some tens of g cm/(s C), which is consistent with the known measurements of ion velocity, ion erosion rate, and specific recoil force. This supports the model of the pressure-gradient-driven plasma acceleration mechanism for the explosive cathode spot cells. The ohmic electric field within the explosive current-carrying plasma has been estimated to be some tens of kV/cm, which is consistent with the known experimental data on cathode potential fall and explosive cell plasma size. This supports the model that assumes the ohmic nature of the cathode potential fall in a vacuum discharge.

The tungsten powder study of the dispenser cathode

International Nuclear Information System (INIS)

Bao Jixiu; Wan Baofei

2006-01-01

The intercorrelation of tungsten powder properties, such as grain size, distribution and morphology, and porous matrix parameters with electron emission capability and longevity of Ba dispenser cathodes has been investigated for the different grain morphologies. It is shown that a fully cleaning step of the tungsten powder is so necessary that the tungsten powder will be reduction of oxide in hydrogen atmosphere above 700 deg. C. The porosity of the tungsten matrix distributes more even and the closed pore is fewer, the average granule size of the tungsten powder distributes more convergent. The porosity of the tungsten matrix and the evaporation of the activator are bigger and the pulse of the cathode is smaller when the granularity is bigger by the analysis of the electronic microscope and diode experiment

The tungsten powder study of the dispenser cathode

Science.gov (United States)

Bao, Ji-xiu; Wan, Bao-fei

2006-06-01

The intercorrelation of tungsten powder properties, such as grain size, distribution and morphology, and porous matrix parameters with electron emission capability and longevity of Ba dispenser cathodes has been investigated for the different grain morphologies. It is shown that a fully cleaning step of the tungsten powder is so necessary that the tungsten powder will be reduction of oxide in hydrogen atmosphere above 700 °C. The porosity of the tungsten matrix distributes more even and the closed pore is fewer, the average granule size of the tungsten powder distributes more convergent. The porosity of the tungsten matrix and the evaporation of the activator are bigger and the pulse of the cathode is smaller when the granularity is bigger by the analysis of the electronic microscope and diode experiment.

MWPC with highly segmented cathode pad readout

International Nuclear Information System (INIS)

Debbe, R.; Fischer, J.; Lissauer, D.

1989-01-01

Experiments being conducted with high energy heavy ion beams at Brookhaven National Laboratory and at CERN have shown the importance of developing position sensitive detectors capable of handling events with high multiplicity in environments of high track density as will also be the case in future high luminosity colliders like SSC and RHIC. In addition, these detectors are required to have a dynamic range wide enough to detect minimum ionizing particles and heavy ions like oxygen or silicon. We present here a description of work being done on a prototype of such a detector at BNL. Results from a similar counter are also presented in this Conference. The ''pad chamber'' is a detector with a cathode area subdivided into a very large number of pixel-like elements such that a charged particle traversing the detector at normal incidence leaves an induced charge on a few localized pads. The pads are interconnected by a resistive strip, and readout amplifiers are connected to the resistive strip at appropriate, carefully determined spacings. The pattern of tracks in a multi-hit event is easily recognized, and a centroid-finding readout system allows position determination to a small fraction of the basic cell size. 5 refs., 9 figs

Using Multispectral Imaging to Measure Temperature Profiles and Emissivity of Large Thermionic Dispenser, Cathodes

International Nuclear Information System (INIS)

Simmons, D.F.; Fortgang, C.M.; Holtkamp, D.B.

2001-01-01

Thermionic dispenser cathodes are widely used in modern high-power microwave tubes. Use of these cathodes has led to significant improvement in performance. In recent years these cathodes have been used in electron linear accelerators (LINACs), particularly in induction LINACs, such as the Experimental Test Accelerator at Lawrence Livermore National Laboratory and the Relativistic Test Accelerator at Lawrence Berkeley National Laboratory. For induction LINACs, the thermionic dispenser cathode provides greater reproducibility, longer pulse lengths, and lower emittance beams than does a field emission cathode. Los Alamos National Laboratory is fabricating a dual-axis X-ray radiography machine called dual-axis radiograph hydrodynamic test (DARHT). The second axis of DARHT consists of a 2-kA, 20-MeV induction LINAC that uses a 3.2-MeV electron gun with a tungsten thermionic-dispenser cathode. Typically the DARHT cathode current density is 10 A/cm 2 at 1050 C. Under these conditions current density is space-charge limited, which is desirable since current density is independent of temperature. At lower temperature (the temperature-limited regime) there are variations in the local current density due to a nonuniform temperature profile. To obtain the desired uniform current density associated with space-charge limited operation, the coolest area on the cathode must be at a sufficiently high temperature so that the emission is space-charge limited. Consequently, the rest of the cathode is emitting at the same space-charge-limited current density but is at a higher temperature than necessary. Because cathode lifetime is such a strong function of cathode temperature, there is a severe penalty for nonuniformity in the cathode temperature. For example, a temperature increase of 50 C means cathode lifetime will decrease by a factor of at least four. Therefore, we are motivated to measure the temperature profiles of our large-area cathodes

A system for long pulse REB generation

International Nuclear Information System (INIS)

Tsuzuki, Tetsuya; Hasegawa, Mitsuru; Narihara, Kazumichi; Tomita, Yukihiro; Kubo, Shin; Kobata, Tadasuke; Mohri, Akihiro.

1987-02-01

A high voltage pulse generator system producing intense relativistic electron beams (REB) (1.5 μs pulse width, 30 kA peak current, 1 MeV energy) was developed to the use of REB ring formation. The system consists of a Marx generator, a transmission line with plastics-water hybrid insulators and a magnetically insulated transmission line connected with a cathode. The system has been well operated more than twenty thousands shots without troubles. (author)

Experimental study of a diod with magnetic insulation at the pulse duration more or equal to 10-5 s

International Nuclear Information System (INIS)

Rojfe, I.M.; Burtsev, V.A.; Vasilevskij, M.A.; Ehngel'ko, V.I.

1980-01-01

Results of the experimental investigation of a heavy-current diod with magnetic insulation are presented. Diod characteristics dependence on magnetic field distribution and magnitude in the accelerating interval has been studied. It is noted that the magnetic insulation of the accelerating tube has permitted to obtain the pulse duration of > or approximately 10 sub(s)sup(-5) at the voltage of > or approximately 400 kV in the tube and electron beam current of 3-4 kA. Maximum insulating magnetic field is 2.5 kOe. It is shown that the pulse duration of electron current in diods with magnetic insulation is limitted by break-down development along the accelerating tube surface. When magnetic field on the cathode is approximately 5kOe thre is a time interval of 4-5μs when the impedance is constant. The difference of diod impedance behaviour in time in these two cases are defined by a distinct expansion of cathode plasma at low magnetic fields. Cathode lateral surface plays a significant role in the process of plasma expantion. When the interelectrode gap is 3-5 cm and the voltage amplitude - < or approximately 400 kV it is possible to obtain tubular electron beams with the pulse duration of 10-15 μs, beam energy of 5-6 kJat a relatively small (approximately equal to 5kOe) magnitudes of magnetic field on the cathode. A possibility is shown to use multipoint graphite cathodes with a large area for obtaining tubular beams. The tubular electron beam of approximately equal to 400 A with the pulse duration of 25 μs have been obtained in the first experiments with such cathode at the voltage amplitude of < or approximately 150 kV. The conclusion is made that the tube magnetic isolation permits to increase considerably the pulse duration

Epoxy-paint stripping using TEA CO2 laser: Determination of threshold fluence and the process parameters

Science.gov (United States)

Kumar, Manoj; Bhargava, P.; Biswas, A. K.; Sahu, Shasikiran; Mandloi, V.; Ittoop, M. O.; Khattak, B. Q.; Tiwari, M. K.; Kukreja, L. M.

2013-03-01

It is shown that the threshold fluence for laser paint stripping can be accurately estimated from the heat of gasification and the absorption coefficient of the epoxy-paint. The threshold fluence determined experimentally by stripping of the epoxy-paint on a substrate using a TEA CO2 laser matches closely with the calculated value. The calculated threshold fluence and the measured absorption coefficient of the paint allowed us to determine the epoxy paint thickness that would be removed per pulse at a given laser fluence even without experimental trials. This was used to predict the optimum scan speed required to strip the epoxy-paint of a given thickness using a high average power TEA CO2 laser. Energy Dispersive X-Ray Fluorescence (EDXRF) studies were also carried out on laser paint-stripped concrete substrate to show high efficacy of this modality.

Pulse plating

CERN Document Server

Hansal, Wolfgang E G; Green, Todd; Leisner, Peter; Reichenbach, Andreas

2012-01-01

The electrodeposition of metals using pulsed current has achieved practical importance in recent years. Although it has long been known that changes in potential, with or without polarity reversal, can significantly affect the deposition process, the practical application of this has been slow to be adopted. This can largely be explained in terms of the complex relationship between the current regime and its effect on the electrodeposition process. In order to harness these effects, an understanding of the anodic and cathodic electrochemical processes is necessary, together with the effects of polarity reversal and the rate of such reversals. In this new monograph, the basics of metal electrodeposition from solution are laid out in great detail in seven distinct chapters. With this knowledge, the reader is able to predict how a given pulse train profile can be adopted to achieve a desired outcome. Equally important is the choice of a suitable rectifier and the ancillary control circuits to enable pulse platin...

Characterization of SiC in DLC/a-Si films prepared by pulsed filtered cathodic arc using Raman spectroscopy and XPS

International Nuclear Information System (INIS)

Srisang, C.; Asanithi, P.; Siangchaew, K.; Pokaipisit, A.; Limsuwan, P.

2012-01-01

DLC/a-Si films were deposited on germanium substrates. a-Si film was initially deposited as a seed layer on the substrate using DC magnetron sputtering. DLC film was then deposited on the a-Si layer via a pulsed filtered cathodic arc (PFCA) system. In situ ellipsometry was used to monitor the thicknesses of the growth films, allowing a precise control over the a-Si and DLC thicknesses of 6 and 9 nm, respectively. It was found that carbon atoms implanting on a-Si layer act not only as a carbon source for DLC formation, but also as a source for SiC formation. The Raman peak positions at 796 cm -1 and 972 cm -1 corresponded to the LO and TO phonon modes of SiC, respectively, were observed. The results were also confirmed using TEM, XPS binding energy and XPS depth profile analysis.

Development of the dense plasma focus for short-pulse applications

Science.gov (United States)

Bennett, N.; Blasco, M.; Breeding, K.; Constantino, D.; DeYoung, A.; DiPuccio, V.; Friedman, J.; Gall, B.; Gardner, S.; Gatling, J.; Hagen, E. C.; Luttman, A.; Meehan, B. T.; Misch, M.; Molnar, S.; Morgan, G.; O'Brien, R.; Robbins, L.; Rundberg, R.; Sipe, N.; Welch, D. R.; Yuan, V.

2017-01-01

The dense plasma focus (DPF) has long been considered a compact source for pulsed neutrons and has traditionally been optimized for the total neutron yield. In this paper, we describe the efforts to optimize the DPF for short-pulse applications by introducing a reentrant cathode at the end of the coaxial plasma gun. The resulting neutron pulse widths are reduced by an average of 21 ±9 % from the traditional long-drift DPF design. Pulse widths and yields achieved from deuterium-tritium fusion at 2 MA are 61.8 ±30.7 ns FWHM and 1.84 ±0.49 ×1012 neutrons per shot. Simulations were conducted concurrently to elucidate the DPF operation and confirm the role of the reentrant cathode. A hybrid fluid-kinetic particle-in-cell modeling capability demonstrates correct sheath velocities, plasma instabilities, and fusion yield rates. Consistent with previous findings that the DPF is dominated by beam-target fusion from superthermal ions, we estimate that the thermonuclear contribution is at the 1% level.

In situ X-ray studies of film cathodes for solid oxide fuel cells

International Nuclear Information System (INIS)

Fuoss, Paul; Chang, Kee-Chul; You, Hoydoo

2013-01-01

Highlights: •Synchrotron X-rays are used to study in operando the structural and chemical changes of LSM and LSCF film cathodes during half-cell operations. •A-site and B-site cations actively segregate or desegregate on the changes of temperature, pO 2 , and electrochemical potential. •Chemical lattice expansions show that oxygen-cathode interface is the primary source of rate-limiting processes. •The surface and subsurface of the LSM and LSCF films have different oxidation-states due to vacancy concentration changes. •Liquid-phase infiltration and coarsening processes of cathode materials into porous YSZ electrolyte backbone were monitored by USAXS. -- Abstract: Synchrotron-based X-ray techniques have been used to study in situ the structural and chemical changes of film cathodes during half-cell operations. The X-ray techniques used include X-ray reflectivity (XR), total-reflection X-ray fluorescence (TXRF), high-resolution diffraction (HRD), ultra-small angle X-ray scattering (USAXS). The epitaxial thin film model cathodes for XR, TXRF, and HRD measurements are made by pulse laser deposition and porous film cathodes for USAX measurements are made by screen printing technique. The experimental results reviewed here include A-site and B-site segregations, lattice expansion, oxidation-state changes during cell operations and liquid-phase infiltration and coarsening of cathode to electrolyte backbone

Metal-oxide-junction, triple point cathodes in a relativistic magnetron

International Nuclear Information System (INIS)

Jordan, N. M.; Gilgenbach, R. M.; Hoff, B. W.; Lau, Y. Y.

2008-01-01

Triple point, defined as the junction of metal, dielectric, and vacuum, is the location where electron emission is favored in the presence of a sufficiently strong electric field. To exploit triple point emission, metal-oxide-junction (MOJ) cathodes consisting of dielectric ''islands'' over stainless steel substrates have been fabricated. The two dielectrics used are hafnium oxide (HfO x ) for its high dielectric constant and magnesium oxide (MgO) for its high secondary electron emission coefficient. The coatings are deposited by ablation-plasma-ion lithography using a KrF laser (0-600 mJ at 248 nm) and fluence ranging from 3 to 40 J/cm 2 . Composition and morphology of deposited films are analyzed by scanning electron microscopy coupled with x-ray energy dispersive spectroscopy, as well as x-ray diffraction. Cathodes are tested on the Michigan Electron Long-Beam Accelerator with a relativistic magnetron, at parameters V=-300 kV, I=1-15 kA, and pulse lengths of 0.3-0.5 μs. Six variations of the MOJ cathode are tested, and are compared against five baseline cases. It is found that particulate formed during the ablation process improves the electron emission properties of the cathodes by forming additional triple points. Due to extensive electron back bombardment during magnetron operation, secondary electron emission also may play a significant role. Cathodes exhibit increases in current densities of up to 80 A/cm 2 , and up to 15% improvement in current start up time, as compared to polished stainless steel cathodes

Model for prediction of strip temperature in hot strip steel mill

International Nuclear Information System (INIS)

Panjkovic, Vladimir

2007-01-01

Proper functioning of set-up models in a hot strip steel mill requires reliable prediction of strip temperature. Temperature prediction is particularly important for accurate calculation of rolling force because of strong dependence of yield stress and strip microstructure on temperature. A comprehensive model was developed to replace an obsolete model in the Western Port hot strip mill of BlueScope Steel. The new model predicts the strip temperature evolution from the roughing mill exit to the finishing mill exit. It takes into account the radiative and convective heat losses, forced flow boiling and film boiling of water at strip surface, deformation heat in the roll gap, frictional sliding heat, heat of scale formation and the heat transfer between strip and work rolls through an oxide layer. The significance of phase transformation was also investigated. Model was tested with plant measurements and benchmarked against other models in the literature, and its performance was very good

Model for prediction of strip temperature in hot strip steel mill

Energy Technology Data Exchange (ETDEWEB)

Panjkovic, Vladimir [BlueScope Steel, TEOB, 1 Bayview Road, Hastings Vic. 3915 (Australia)]. E-mail: Vladimir.Panjkovic@BlueScopeSteel.com

2007-10-15

Proper functioning of set-up models in a hot strip steel mill requires reliable prediction of strip temperature. Temperature prediction is particularly important for accurate calculation of rolling force because of strong dependence of yield stress and strip microstructure on temperature. A comprehensive model was developed to replace an obsolete model in the Western Port hot strip mill of BlueScope Steel. The new model predicts the strip temperature evolution from the roughing mill exit to the finishing mill exit. It takes into account the radiative and convective heat losses, forced flow boiling and film boiling of water at strip surface, deformation heat in the roll gap, frictional sliding heat, heat of scale formation and the heat transfer between strip and work rolls through an oxide layer. The significance of phase transformation was also investigated. Model was tested with plant measurements and benchmarked against other models in the literature, and its performance was very good.

Effect of pulsed duty cycle control on tribological and corrosion properties of AISI-316 in cathodic cage plasma nitriding

Science.gov (United States)

Naeem, M.; Raza, H. A.; Shafiq, M.; Zaka-ul-Islam, M.; Iqbal, Javed; Díaz-Guillén, J. C.; Zakaullah, M.

2017-11-01

Austenitic stainless steels are of prime importance in many industrial sectors because of their excellent corrosion resistance; however, their poor mechanical and tribological features lead to their reduced applicability. In this regard, low-temperature cathodic cage plasma nitriding (CCPN) can be used to improve surface properties of steels without scarifying the inherent corrosion resistance. In this study, AISI-316 samples are processed in CCPN reactor at a temperature of 400 °C, for the treatment time of 4 h, at a pressure of 150 Pa and variable pulsed duty cycle (15-75%). The microstructure and mechanical features are analyzed using x-ray diffraction, scanning electron microscopy, microhardness tester and ball-on-disc wear tester. The anodic polarization test in 3.5% NaCl is conducted to examine the corrosion properties. The results show that hardness is enhanced up to 1327 HV at low duty cycle, which is considerably higher than base material (278 HV). The wear rate is found to be reduced up to 90% over base material by processing at low duty cycle. The base material exhibits severe abrasive wear, and the nitrided sample has dominant adhesive wear. The corrosion rate is found to be reduced up to 95% over base material for the sample nitrided at low duty cycle. This study shows that wear and corrosion resistance in CCPN can be significantly boosted by reducing the pulsed duty cycle.

Abnormal polarity effect in nanosecond-pulse breakdown of SF6 and nitrogen

International Nuclear Information System (INIS)

Shao, Tao; Tarasenko, Victor F.; Zhang, Cheng; Beloplotov, Dmitry S.; Yang, Wenjin; Lomaev, Mikhail I.; Zhou, Zhongsheng; Sorokin, Dmitry A.; Yan, Ping

2014-01-01

The breakdown of gas gaps in an inhomogeneous electric field at subnanosecond and nanosecond voltage pulse rise times are studied, and the famous polarity effect in point-to-plane gaps is investigated. It is shown that at a voltage pulse rise time of ∼0.5 ns, the inversion of polarity effect takes place not only in electronegative gases such as SF 6 , but also occurs in electropositive nitrogen. The inversion of polarity effect is related to a delay of electron emission from the plane cathode on arrival of the ionization wave front anode to the cathode. It is found that with a voltage pulse rise time of ∼0.5 ns, the inversion of polarity effect occurs at SF 6 and SF 6 –N 2 pressures of 0.25 MPa and lower, and with a voltage pulse rise time of 15 ns, at a SF 6 pressure lower than 0.12 MPa.

Intense relativistic electron beam generation from KALI-5000 pulse accelerator

International Nuclear Information System (INIS)

Roy, A.; Mondal, J.; Mitra, S.; Durga Praveen Kumar, D.; Sharma, Archana; Nagesh, K.V.; Chakravarthy, D.P.

2006-01-01

Intense Relativistic Electron Beam (IREB) with parameters 420 keV, 22 kA, 100 ns has been generated from indigenously developed pulse power system KALI- 5000. High current electron beam is generated from explosive field emission graphite cathodes. Studies have been conducted by changing the diameter of graphite cathode and also the anode cathode gap. In order to avoid prepulse effect it was concluded that anode cathode (AK) gap should be kept larger than estimated by the Child Langmuir relation. Beam voltage has been measured by a copper sulphate voltage divider, beam current by a self integrating Rogowski coil and B-dot probe. Electron beam diode Impedance and Perveance were obtained from the experimentally measured beam voltage and current. (author)

Ionization waves in the pre-breakdown phase of a pulsed capillary discharge

International Nuclear Information System (INIS)

Favre, M.; Lenero, A.M.; Chuaqui, H.; Mitchell, I.; Wyndham, E.; Choi, P.; Dumitrescu, C.; Mond, M.; Rutkevich, I.; Kaufman, Y.

2001-01-01

We present experimental observations of ionization waves in pulsed hollow cathode capillary discharges. When the capillary shield is at the anode potential, an anode directed ionization wave, with characteristic speed ∼10 7 m/s, is observed. When the capillary shield is at the cathode potential, a cathode directed slower ionization wave, with characteristic speed ∼10 4 m/s, is observed. The several orders of magnitude difference in the ionization wave speed can be attributed to the different initial electric field configuration in both polarities

Attempts to cathodically reduce boron oxides to borohydride in aqueous solution

International Nuclear Information System (INIS)

McLafferty, J.; Colominas, S.; Macdonald, D.D.

2010-01-01

Sodium borohydride is being considered as a chemical hydrogen storage material (hydrogen being released through hydrolysis) and as an anodic fuel for fuel cells. However, the current cost of sodium borohydride is prohibitively high for automotive applications. Thus, there is interest in recycling the by-product of the hydrolysis or oxidation reaction, sodium metaborate. Numerous patents claim that this reaction is feasible in aqueous solution. Here, we report extensive experiments based upon methods outlined in the patents (particularly, the so-called direct reduction using high overpotential cathode materials). We also attempt to address concerns not discussed in the patents. In particular, to the authors' knowledge, previous reports have not addressed electrostatic repulsion of metaborate anion from the cathode. We further report several methods that were designed to overcome this problem: (1) use of a cathode material having a very negative potential of zero charge, (2) modification of the electrical double layer by using specifically adsorbing tetraalkylammonium hydroxides, (3) use of a rectangular wave pulse, and (4) use of chemically modified cathodes. None of these methods produced measurable quantities of borohydride. We then speculate as to why this reaction is not feasible, at least in aqueous solutions.

Effects of fast monoenergetic electrons on the ion dynamics near the cathode in a pulsed direct current plasma sheath

International Nuclear Information System (INIS)

Sharifian, M.; Shokri, B.

2008-01-01

A detailed one-dimensional simulation of the ion dynamics of the plasma sheath near a substrate (cathode) in the presence of fast monoenergetic electrons has been carried out in this article. The sheath evolution is investigated by using a fluid model assuming that the ions, plasma electrons and monoenergetic, fast electrons act as three fluids (fluid approach). The effect of the density of fast electrons on the ion density, ion velocity, and ion energy near the cathode and the evolution of the sheath boundary in front of the cathode are separately explored. Also, the variation of the ion velocity and ion density at the vicinity of the cathode as a function of time is investigated in the absence and presence of the electron beam. Results indicate that the presence of fast electrons in the sheath causes significant change in the sheath thickness and therefore basically changes the ion velocity, ion density, and ion impact energy on the cathode compared to the absence of the electron beam case

Picosecond ion pulses from an EN tandem created by a femtosecond Ti:sapphire laser

International Nuclear Information System (INIS)

Carnes, K.D.; Cocke, C.L.; Chang, Z.; Ben-Itzhak, I.; Needham, H.V.; Rankin, A.

2007-01-01

As the James R. Macdonald Laboratory at Kansas State University continues its transformation from an ion collisions facility to an ultrafast laser/ion collisions facility, we are looking for novel ways to combine our traditional accelerator expertise with our new laser capabilities. One such combination is to produce picosecond pulses of stripping gas ions in the high energy accelerating tube of our EN tandem by directing ∼100 fs, sub-milliJoule laser pulses up the high energy end of the tandem toward a focusing mirror at the terminal. Ion pulses from both stripping and residual gas have been produced and identified, with pulse widths thus far on the order of a nanosecond. This width represents an upper limit, as it is dominated by pulse-to-pulse jitter in the ion time-of-flight (TOF) and is therefore not a true representation of the actual pulse width. In this paper, we describe the development process and report on the results to date. Conditions limiting the minimum temporal pulse width, such as tandem terminal ripple, thermal motion of the gas and space charge effects, are also outlined

Design of pulse transformers for PFL charging

International Nuclear Information System (INIS)

Rohwein, G.J.

1979-01-01

Air core pulse transformers powered by low voltage capacitor banks can be simple efficient systems for charging high-voltage (0.5 to 3 MV), pulse forming transmission lines (PFL) such as those used in electron and ion beam accelerators. In these applications pulse transformers must have the combined capability of high voltage endurance and high energy transfer efficiency, particularly in repetitive pulse systems where these features are of primary importance. The design of shielded, high-voltage, spiral, strip transformers which fulfill these requirements is described in this paper. Transformers of this type have been tested in three systems which operate with greater than 90% transfer efficiency and have not failed in over 10 7 shots

3.5 MeV pulsed power system for LIA injector

International Nuclear Information System (INIS)

Li Jin; Dai Guangsen; Liu Xiaoping; Zhang Kaizhi; Li Xin; Li Yuan; Xia Liansheng; Xie Min; Zhang Linwen; Deng Jianjun; Ding Bonan

2005-01-01

A 3.5 MeV injector for linear induction accelerator has been built up at Institute of Fluid Physics, China Academy of Engineering Physics. The injector is based on the principle of inductive adder. It consists of 12 induction cells. Seven induction cells are on the cathode stem side, which are connected in series, and provide about 2 MV on the cathode of the diode. The other five are connected in series on the anode stem side and provide about 1.5 MV on the anode of the diode. A 3.5 MV pulsed power system to provide energy for the injector has been designed, which consists of two Marx generators, 12 water insulated Blumleins, and trigger system. Charge voltage of each water insulated Blumlein is 200 kV. A 300 kV/90 ns high voltage pulse is fed into one induction cell since load impedance is higher. The pulsed power system can generate an intense electron beam with 2-3 kA. (authors)

Extension of HPM Pulse Duration by Cesium Iodide Cathodes in Crossed Field Devices

National Research Council Canada - National Science Library

Benford, James

1998-01-01

.... The introduction of cathodes made from Cesium Iodide-coated (CsI) carbon fiber has shown plasma speeds reduced by factors of a few from uncoated carbon fiber, but previous work was at low diode fields of a few 10's of kV/cm...

Pseudospark switches (PSS) for pulsed power applications

Energy Technology Data Exchange (ETDEWEB)

Heine, F; Prucker, U; Frank, K; Goertler, A; Schwandner, A; Tkotz, R; Hoffmann, D H.H.; Christiansen, J [Univ. of Erlangen (Germany). Physics Dept. I

1997-12-31

Based on the pseudospark discharge, a low pressure gas discharge in a special geometry, fast closing switches for different pulsed power applications have been designed. Medium power PSS ({<=} 30 kA peak current) were used in laser circuits whereas high current PSS are tested successfully in high current pulsed power applications ({<=} 200 kA). For currents of a few kA the discharge is supported by cathode spots on the cold cathode surface. For higher currents, anode activity is observed too. Inserting semiconductor material seems not only to suppress high erosive spot formation but to support diffuse large-area electrode emission. A different approach to solving the problem of lowering the erosion rate is the multichannel PSS (MUPS). In order to distribute the discharge current to more than one single channel, three or more discharge channels are radial or coaxial arranged. With regard to high voltage applications the maximum hold-off voltage was increased by adding an intermediate electrode. (author). 1 figs., 12 refs.

Electrochemical stripping determination of traces of copper, lead, cadmium and zinc in zirconium metal and zirconium dioxide

International Nuclear Information System (INIS)

Stulik, K.; Beran, P.; Dolezal, J.; Opekar, F.

1978-01-01

Procedures have been developed for the determination of copper, lead, cadmium and zinc in zirconium metal and zirconium dioxide, at concentrations of 1ppm or less. Zirconium metal was dissolved in sulphuric acid, and zirconium dioxide decomposed under pressure with hydrofluoric acid. Sample solutions were prepared in dilute sulphuric acid. For the stripping determination, the sample solution was either mixed with a complexing tartrate base electrolyte or the pre-electrolysis was carried out in acid solution, with the acid solution being exchanged for a pure base electrolyte (e.g. an acetate buffer) for the stripping step. The stripping step was monitored by d.c., differential pulse and Kalousek commutator voltammetry and the three methods were compared. A stationary mercury-drop electrode can generally be used for all the methods, whereas a mercury-film electrode is suitable only for the d.c. voltammetric determination of copper, lead and cadmium, as pulse measurements with films are poorly reproducible and the electrodes are easily damaged. The relative standard deviation does not exceed 20%. Some samples contained relatively large amounts of copper, which is best separated by electrodeposition on a platinum electrode. (author)

Bent paths of a positive streamer and a cathode-directed spark leader in diffuse discharges preionized by runaway electrons

Energy Technology Data Exchange (ETDEWEB)

Zhang, Cheng; Shao, Tao, E-mail: st@mail.iee.ac.cn; Wang, Ruixue; Yan, Ping [Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Key Laboratory of Power Electronics and Electric Drive, Chinese Academy of Sciences, Beijing 100190 (China); Tarasenko, Viktor F.; Beloplotov, Dmitry V.; Lomaev, Mikhail I.; Sorokin, Dmitry A. [Institute of High Current Electronics, Russian Academy of Science, Tomsk 634055 (Russian Federation); National Research Tomsk State University, 36 Lenin Ave., Tomsk 634050 (Russian Federation)

2015-03-15

Diffuse discharges preionized by runaway electrons can produce large-area homogeneous discharges at elevated pressures, which is an intriguing phenomenon in the physics of pulsed discharges. In this paper, runaway-electron-preionized diffuse discharge (REP DD) was obtained in a wide pressure range (0.05–0.25 MPa), and under certain conditions a positive streamer and a cathode-directed spark leader could be observed to propagate at some angles to the applied (background) electric field lines. For a 16-mm gap at an air pressure of 0.08–0.1 MPa, the percentage of pulses in which such propagation is observed is about 5%–50% of their total number, and in the other pulses such bent paths could not be observed because there is even no streamer or cathode-directed spark leader in diffuse discharges. In our opinion, such propagation of the positive streamer and the cathode-directed spark leader at some angle to the background electric field lines owes to different increase rates of the electron density in different regions of the discharge volume under REP DD conditions. Therefore, during the formation of a REP DD, the increase of the electron density is inhomogeneous and nonsimultaneous, resulting in an electron density gradient at the ionization wave front.

Bent paths of a positive streamer and a cathode-directed spark leader in diffuse discharges preionized by runaway electrons

International Nuclear Information System (INIS)

Zhang, Cheng; Shao, Tao; Wang, Ruixue; Yan, Ping; Tarasenko, Viktor F.; Beloplotov, Dmitry V.; Lomaev, Mikhail I.; Sorokin, Dmitry A.

2015-01-01

Diffuse discharges preionized by runaway electrons can produce large-area homogeneous discharges at elevated pressures, which is an intriguing phenomenon in the physics of pulsed discharges. In this paper, runaway-electron-preionized diffuse discharge (REP DD) was obtained in a wide pressure range (0.05–0.25 MPa), and under certain conditions a positive streamer and a cathode-directed spark leader could be observed to propagate at some angles to the applied (background) electric field lines. For a 16-mm gap at an air pressure of 0.08–0.1 MPa, the percentage of pulses in which such propagation is observed is about 5%–50% of their total number, and in the other pulses such bent paths could not be observed because there is even no streamer or cathode-directed spark leader in diffuse discharges. In our opinion, such propagation of the positive streamer and the cathode-directed spark leader at some angle to the background electric field lines owes to different increase rates of the electron density in different regions of the discharge volume under REP DD conditions. Therefore, during the formation of a REP DD, the increase of the electron density is inhomogeneous and nonsimultaneous, resulting in an electron density gradient at the ionization wave front

Study on the characteristics of barrier free surface discharge driven by repetitive nanosecond pulses at atmospheric pressure

Energy Technology Data Exchange (ETDEWEB)

Lei, Pang; Qiaogen, Zhang [State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Xi' an 710049 (China); Kun, He [China Electric Power Research Institute, Beijing 100192 (China); Chunliang, Liu [State Key Laboratory for Physical Electronics and Devices, Xi' an Jiaotong University, Xi' an 710049 (China)

2016-05-15

Nanosecond pulsed plasma has an enormous potential in many applications. In this paper, the characteristics of barrier free nanosecond pulsed surface discharge are investigated by the use of an actuator with a strip-strip film electrode configuration, including the effect of electrode width and the gap distance on the plasma morphology and electrical characteristics at atmospheric pressure. It was found that it is relative easier to generate a quasi uniform discharge with a thinner electrode width and a smaller gap distance. The underlying physical mechanism was also discussed. Besides that, the influence of airflow on repetitive pulsed surface discharge was examined. By comparing to the discharge produced by two different pulse waveforms in airflows, we found that the discharge driven by a faster pulse behaves more stable. Finally, a model was developed to analyze the interaction of the airflow and the discharge channels.

Study of electrode pattern design for a CZT-based PET detector.

Science.gov (United States)

Gu, Y; Levin, C S

2014-06-07

We are developing a 1 mm resolution small animal positron emission tomography (PET) system using 3D positioning cadmium zinc telluride photon detectors comprising 40 mm × 40 mm × 5 mm crystals metalized with a cross-strip electrode pattern with a 1 mm anode strip pitch. We optimized the electrode pattern design for intrinsic sensitivity and spatial, energy and time resolution performance using a test detector comprising cathode and steering electrode strips of varying dimensions. The study found 3 and 5 mm width cathode strips locate charge-shared photon interactions near cathode strip boundaries with equal precision. 3 mm width cathode strips exhibited large time resolution variability as a function of photon interaction location between the anode and cathode planes (~26 to ~127.5 ns full width at half maximum (FWHM) for 0.5 mm and 4.2 mm depths, respectively). 5 mm width cathode strips by contrast exhibited more stable time resolution for the same interaction locations (~34 to ~83 ns FWHM), provided more linear spatial positioning in the direction orthogonal to the electrode planes, and as much as 68.4% improvement in photon sensitivity over the 3 mm wide cathode strips. The results were understood by analyzing the cathode strips' weighting functions, which indicated a stronger 'small pixel' effect in the 3 mm wide cathode strips. Photon sensitivity and anode energy resolution were seen to improve with decreasing steering electrode bias from 0 to -80 V w.r.t. the anode potential. A slight improvement in energy resolution was seen for wider steering electrode strips (400 versus 100 µm) for charge-shared photon interactions. Although this study successfully focused on electrode pattern features for PET performance, the results are generally applicable to semiconductor photon detectors employing cross-trip electrode patterns.

Time-resolved investigation of an asymmetric bipolar pulsed magnetron deposition discharge: Influence of pressure

NARCIS (Netherlands)

Dunger, Th.; Welzel, Th.; Welzel, S.; Richter, F.

2005-01-01

A bipolar pulsed magnetron deposition discharge has been studied with pulse frequencies of 100 and 150 kHz, respectively. The discharge was operated in an argon/oxygen mixture at different total pressures with a circular magnesium target as cathode. Time-resolved Langmuir double probe measurements

Differential Pulse Anodic Stripping Voltammetry for Mercury Determination

OpenAIRE

Vereștiuc Paul C.; Tucaliuc Oana-Maria; Breabăn Iuliana G.; Crețescu Igor; Nemțoi Gheorghe

2015-01-01

In the present work voltammetric investigations have been performed on HgCl2 aqueous solutions prepared from a Cz 9024 reagent. Carbon paste electrode (CPE), eriochrome black T modified carbon paste electrode (MCPE/EBT) and KCl 1M as background electrolyte, were involved within the experimental procedures. Cyclic voltammetry (CV) has been performed in order to compare the behaviour of the two electrodes in both K3[Fe(CN)6] and mercury calibration aqueous solution. Differential pulse anodic st...

Effect of Pulse Polarity on Thresholds and on Non-monotonic Loudness Growth in Cochlear Implant Users.

Science.gov (United States)

Macherey, Olivier; Carlyon, Robert P; Chatron, Jacques; Roman, Stéphane

2017-06-01

Most cochlear implants (CIs) activate their electrodes non-simultaneously in order to eliminate electrical field interactions. However, the membrane of auditory nerve fibers needs time to return to its resting state, causing the probability of firing to a pulse to be affected by previous pulses. Here, we provide new evidence on the effect of pulse polarity and current level on these interactions. In experiment 1, detection thresholds and most comfortable levels (MCLs) were measured in CI users for 100-Hz pulse trains consisting of two consecutive biphasic pulses of the same or of opposite polarity. All combinations of polarities were studied: anodic-cathodic-anodic-cathodic (ACAC), CACA, ACCA, and CAAC. Thresholds were lower when the adjacent phases of the two pulses had the same polarity (ACCA and CAAC) than when they were different (ACAC and CACA). Some subjects showed a lower threshold for ACCA than for CAAC while others showed the opposite trend demonstrating that polarity sensitivity at threshold is genuine and subject- or electrode-dependent. In contrast, anodic (CAAC) pulses always showed a lower MCL than cathodic (ACCA) pulses, confirming previous reports. In experiments 2 and 3, the subjects compared the loudness of several pulse trains differing in current level separately for ACCA and CAAC. For 40 % of the electrodes tested, loudness grew non-monotonically as a function of current level for ACCA but never for CAAC. This finding may relate to a conduction block of the action potentials along the fibers induced by a strong hyperpolarization of their central processes. Further analysis showed that the electrodes showing a lower threshold for ACCA than for CAAC were more likely to yield a non-monotonic loudness growth. It is proposed that polarity sensitivity at threshold reflects the local neural health and that anodic asymmetric pulses should preferably be used to convey sound information while avoiding abnormal loudness percepts.

Performance of MSGCs with cathode readout

International Nuclear Information System (INIS)

Cremaldi, L.; Finocchiaro, G.; Rajagopalan, S.; Schamberger, D.

1996-01-01

The performance of a telescope of Micro-Strip Gas Chambers (MSGC) has been studied in a beam of minimum ionizing particles. Detectors of two different pitches have been studied. The position resolutions is obtained by reading out the cathodes and interpolating based on the amplitude of the signals. The position of the hit in the chamber is found to differ systematically from the cluster centroid position. A correction method is derived from the data and applied to improve the resolution. After correction, the spatial resolution of chambers with 200 μm pitch is found to be 42 μm, and for the 400 μm pitch detectors the resolution is 42 μm. The improved interpolation for the 400 μm pitch chamber can be understood in terms of the better signal to noise observed for the 400 μm pitch detectors. The degradation in resolution as a function of angle of track incidence is also expected to be less for the larger pitch chambers

Lifetime Studies of Cs2Te Cathodes at the Phin RF Photoinjector at CERN

CERN Document Server

Hessler, C; Divall Csatari, M; Doebert, S; Fedosseev, V

2012-01-01

The PHIN photoinjector has been developed to study the feasibility of a photoinjector option for the CLIC (Compact LInear Collider) drive beam as an alternative to the baseline design, using a thermionic gun. The CLIC drive beam requires a high charge of 8.4 nC per bunch in 0.14 ms long trains, with 2 ns bunch spacing and 50 Hz macro pulse repetition rate, which corresponds to a total charge per macro pulse of 0.59 mC. This means unusually high peak and average currents for photoinjectors and is challenging concerning the cathode lifetime. In this paper detailed studies of the lifetime of Cs2Te cathodes, produced by the co-evaporation technique, are presented with respect to bunch charge, train length and vacuum level. Furthermore, the impact of the train length and bunch charge on the vacuum level will be discussed and steps to extend the lifetime will be outlined.

Proof-of-Concept Experiments on a Gallium-Based Ignitron for Pulsed Power Applications

Science.gov (United States)

Ali, H. K.; Hanson, V. S.; Polzin, K. A.; Pearson, J. B.

2015-01-01

Ignitrons are electrical switching devices that operate at switching times that are on the order of microseconds, can conduct high currents of thousands of amps, and are capable of holding off tens of thousands of volts between pulses. They consist of a liquid metal pool within an evacuated tube that serves both the cathode and the source of atoms and electrons for an arc discharge. Facing the liquid metal pool is an anode suspended above the cathode, with a smaller ignitor electrode tip located just above the surface of the cathode. The ignitron can be charged to significant voltages, with a potential difference of thousands of volts between anode and cathode. When an ignition pulse is delivered from the ignitor electrode to the cathode, a small amount of the liquid metal is vaporized and subsequently ionized, with the high voltage between the anode and cathode causing the gas to bridge the gap between the two electrodes. The electrons and ions move rapidly towards the anode and cathode, respectively, with the ions liberating still more atoms from the liquid metal cathode surface as a high-current plasma arc discharge is rapidly established. This arc continues in a self-sustaining fashion until the potential difference between the anode and cathode drops below some critical value. Ignitrons have been used in a variety of pulsed power applications, including the railroad industry, industrial chemical processing, and high-power arc welding. In addition, they might prove useful in terrestrial power grid applications, serving as high-current fault switches, quickly shunting dangerous high-current or high-voltage spikes safely to ground. The motivation for this work stemmed from the fact that high-power, high-reliability, pulsed power devices like the ignitron have been used for ground testing in-space pulsed electric thruster technologies, and the continued use of ignitrons could prove advantageous to the future development and testing of such thrusters. Previous

Electron emission of cathode holder of vacuum diode of an intense electron-beam accelerator and its effect on the output voltage

Directory of Open Access Journals (Sweden)

Xin-Bing Cheng

2011-04-01

Full Text Available The vacuum diode which is used to generate relativistic electron beams is one of the most important parts of a pulsed-power modulator. In this paper, the electron emission of cathode holder of a vacuum diode and its effect on the output voltage is investigated by experiments on an intense electron-beam accelerator with 180 ns full width at half maximum and 200–500 kV output voltage. First, the field emission is analyzed and the electric field of the vacuum chamber is calculated. Then, the flatness of the output voltage is discussed before and after adding an insulation plate when a water load is used. It is found that the electron emission at the edges of the cathode holder is the main reason to cause the change of the flatness. Last, a piece of polyester film is used as a target to further show the electron emission of the cathode holder. This analysis shows that decreasing the electron emission of the cathode holder in such a pulse power modulator could be a good way to improve the quality of the output voltage.

Generation of Femtosecond Electron and Photon Pulses

CERN Document Server

Thongbai, Chitrlada; Kangrang, Nopadol; Kusoljariyakul, Keerati; Rhodes, Michael W; Rimjaem, Sakhorn; Saisut, Jatuporn; Vilaithong, Thiraphat; Wichaisirimongkol, Pathom; Wiedemann, Helmut

2005-01-01

Femtosecond electron and photon pulses become a tool of interesting important to study dynamics at molecular or atomic levels. Such short pulses can be generated from a system consisting of an RF-gun with a thermionic cathode, an alpha magnet as a magnetic bunch compressor, and a linear accelerator. The femtosecond electron pulses can be used directly or used as sources to produce electromagnetic radiation of equally short pulses by choosing certain kind of radiation pruduction processes. At the Fast Neutron Research Facility (Thailand), we are especially interested in production of radiation in Far-infrared and X-ray regime. In the far-infrared wavelengths which are longer than the femtosecond pulse length, the radiation is emitted coherently producing intense radiation. In the X-ray regime, development of femtosecond X-ray source is crucial for application in ultrafast science.

Adsorptive stripping voltammetric behaviour of copper complexes of some heterocyclic azo compounds.

Science.gov (United States)

Farias, P A; Ferreira, S L; Ohara, A K; Bastos, M B; Goulart, M S

1992-10-01

Controlled adsorptive accumulation of copper complexed with TAN, TAC, TAR and TAM (heterocyclic azo-compounds) on a static mercury drop electrode provides the basis for the direct stripping measurement of this element in the nanomolar concentration level. The ligand TAN exhibited great sensitivity and better separation of the peak current of the ligand in relation to the complex. The reduction current of adsorbed complex ions of copper is measured by linear scan cathodic stripping voltammetry, preceded by a period of accumulation of a few minutes. The peak potential is at approximately -0.37 V vs. Ag/AgCl. Optimal experimental parameters were found to be a TAN concentration of 1 x 10(-5)M, an accumulation potential of -0.22 V, and a solution pH of 3.7 (acetate buffer). The detection limit is 0.8nM after a 5-min accumulation with a stirred solution, and the response is linear up to 50 mug/l. Many common cations and anions do not interfere in the determination of copper. The interference of titanium is eliminated by addition of fluoride ion. Results are reported for a fresh water sample.

The Graphene/l-Cysteine/Gold-Modified Electrode for the Differential Pulse Stripping Voltammetry Detection of Trace Levels of Cadmium

Directory of Open Access Journals (Sweden)

Yu Song

2016-06-01

Full Text Available Cadmium(II is a common water pollutant with high toxicity. It is of significant importance for detecting aqueous contaminants accurately, as these contaminants are harmful to human health and environment. This paper describes the fabrication, characterization, and application of an environment-friendly graphene (Gr/l-cysteine/gold electrode to detect trace levels of cadmium (Cd by differential pulse stripping voltammetry (DPSV. The influence of hydrogen overflow was decreased and the current response was enhanced because the modified graphene extended the potential range of the electrode. The Gr/l-cysteine/gold electrode showed high electrochemical conductivity, producing a marked increase in anodic peak currents (vs. the glass carbon electrode (GCE and boron-doped diamond (BDD electrode. The calculated detection limits are 1.15, 0.30, and 1.42 µg/L, and the sensitivities go up to 0.18, 21.69, and 152.0 nA·mm−2·µg−1·L for, respectively, the BDD electrode, the GCE, and the Gr/l-cysteine/gold electrode. It was shown that the Gr/l-cysteine/gold-modified electrode is an effective means for obtaining highly selective and sensitive electrodes to detect trace levels of cadmium.

Subnanosecond breakdown development in high-voltage pulse discharge: Effect of secondary electron emission

Science.gov (United States)

Alexandrov, A. L.; Schweigert, I. V.; Zakrevskiy, Dm. E.; Bokhan, P. A.; Gugin, P.; Lavrukhin, M.

2017-10-01

A subnanosecond breakdown in high-voltage pulse discharge may be a key tool for superfast commutation of high power devices. The breakdown in high-voltage open discharge at mid-high pressure in helium was studied in experiment and in kinetic simulations. The kinetic model of electron avalanche development was constructed, based on PIC-MCC simulations, including dynamics of electrons, ions and fast helium atoms, produced by ions scattering. Special attention was paid to electron emission processes from cathode, such as: photoemission by Doppler-shifted resonant photons, produced in excitation processes involving fast atoms; electron emission by ions and fast atoms bombardment of cathode; the secondary electron emission (SEE) by hot electrons from bulk plasma. The simulations show that the fast atoms accumulation is the main reason of emission growth at the early stage of breakdown, but at the final stage, when the voltage on plasma gap diminishes, namely the SEE is responsible for subnanosecond rate of current growth. It was shown that the characteristic time of the current growth can be controlled by the SEE yield. The influence of SEE yield for three types of cathode material (titanium, SiC, and CuAlMg-alloy) was tested. By changing the pulse voltage amplitude and gas pressure, the area of existence of subnanosecond breakdown is identified. It is shown that in discharge with SiC and CuAlMg-alloy cathodes (which have enhanced SEE) the current can increase with a subnanosecond characteristic time value as small as τs = 0.4 ns, for the pulse voltage amplitude of 5÷12 kV. An increase of gas pressure from 15 Torr to 30 Torr essentially decreases the time of of current front growth, whereas the pulse voltage variation weakly affects the results.

Electronic system for recording proportional counter rare pulses with the pulse shape analysis

International Nuclear Information System (INIS)

Barabanov, I.R.; Gavrin, V.N.; Zakharov, Yu.I.; Tikhonov, A.A.

1984-01-01

The anutomated system for recording proportional counter rare pulses is described. The proportional counters are aimed at identification of 37 Ar and H7 1 Gr decays in chemical radiation detectors of solar neutrino. Pulse shape recording by means of a storage oscilloscope and a TV display is performed in the system considered besides two-parametric selection of events (measurement of pulse amplitude in a slow channel and the amplitude of pulse differentiated with time constant of about 10 ns in a parallel fast channel). Pulse discrimination by a front rise rate provides background decrease in the 55 Fe range (5.9 keV) by 6 times; the visual analysis of pulse shapes recorded allows to decrease the background additionally by 25-30%. The background counting rate in the 55 Fe range being equal to 1 pulse per 1.5 days, is obtained when using the installation described above, as well as the passive Pb shield 5 cm thick, and the active shield based on the anticoincidence NaI(Tl) detector with the cathode 5.6 mm in-diameter made of Fe fabircated by zone melting. The installation described allows to reach the background level of 0.6 pulse/day (the total coefficient of background attenuation is 400). Further background decrease is supposed to be provided by installation allocation in the low-noise underground laboratory of the Baksan Neutrino Observatory

A 6.4 kV pulse generator with transformations

International Nuclear Information System (INIS)

Bastein, W.L.

1989-01-01

The possibility has been investigated to perform a pulse generator which generates pulse for the cathode of the injector of the NIKHEF electron accelerator, which generates pulses of 6.4 kV with sides of 100 ns a duration of 2 to 50 microseconds and a frequency of 2500 Hz. The voltage ripple should be smaller than frequency part and one for the high-frequency part, it is possible to generate a pulse which fulfills the requirements with regard to the sides. However installing an tuning of circuits in order to obtain a sufficiently flat pulse will cost much time. Moreover the losses are such high that it deserves recommendation to investigate the possibility ot generate the pulse with a number of MOSFets connected in series. (author). 8 refs.; 8 figs.; 14 photos; 1 tab

Influence of cathode geometry on electron dynamics in an ultrafast electron microscope

Directory of Open Access Journals (Sweden)

Shaozheng Ji

2017-09-01

Full Text Available Efforts to understand matter at ever-increasing spatial and temporal resolutions have led to the development of instruments such as the ultrafast transmission electron microscope (UEM that can capture transient processes with combined nanometer and picosecond resolutions. However, analysis by UEM is often associated with extended acquisition times, mainly due to the limitations of the electron gun. Improvements are hampered by tradeoffs in realizing combinations of the conflicting objectives for source size, emittance, and energy and temporal dispersion. Fundamentally, the performance of the gun is a function of the cathode material, the gun and cathode geometry, and the local fields. Especially shank emission from a truncated tip cathode results in severe broadening effects and therefore such electrons must be filtered by applying a Wehnelt bias. Here we study the influence of the cathode geometry and the Wehnelt bias on the performance of a photoelectron gun in a thermionic configuration. We combine experimental analysis with finite element simulations tracing the paths of individual photoelectrons in the relevant 3D geometry. Specifically, we compare the performance of guard ring cathodes with no shank emission to conventional truncated tip geometries. We find that a guard ring cathode allows operation at minimum Wehnelt bias and improve the temporal resolution under realistic operation conditions in an UEM. At low bias, the Wehnelt exhibits stronger focus for guard ring than truncated tip cathodes. The increase in temporal spread with bias is mainly a result from a decrease in the accelerating field near the cathode surface. Furthermore, simulations reveal that the temporal dispersion is also influenced by the intrinsic angular distribution in the photoemission process and the initial energy spread. However, a smaller emission spot on the cathode is not a dominant driver for enhancing time resolution. Space charge induced temporal broadening

Influence of cathode geometry on electron dynamics in an ultrafast electron microscope.

Science.gov (United States)

Ji, Shaozheng; Piazza, Luca; Cao, Gaolong; Park, Sang Tae; Reed, Bryan W; Masiel, Daniel J; Weissenrieder, Jonas

2017-09-01

Efforts to understand matter at ever-increasing spatial and temporal resolutions have led to the development of instruments such as the ultrafast transmission electron microscope (UEM) that can capture transient processes with combined nanometer and picosecond resolutions. However, analysis by UEM is often associated with extended acquisition times, mainly due to the limitations of the electron gun. Improvements are hampered by tradeoffs in realizing combinations of the conflicting objectives for source size, emittance, and energy and temporal dispersion. Fundamentally, the performance of the gun is a function of the cathode material, the gun and cathode geometry, and the local fields. Especially shank emission from a truncated tip cathode results in severe broadening effects and therefore such electrons must be filtered by applying a Wehnelt bias. Here we study the influence of the cathode geometry and the Wehnelt bias on the performance of a photoelectron gun in a thermionic configuration. We combine experimental analysis with finite element simulations tracing the paths of individual photoelectrons in the relevant 3D geometry. Specifically, we compare the performance of guard ring cathodes with no shank emission to conventional truncated tip geometries. We find that a guard ring cathode allows operation at minimum Wehnelt bias and improve the temporal resolution under realistic operation conditions in an UEM. At low bias, the Wehnelt exhibits stronger focus for guard ring than truncated tip cathodes. The increase in temporal spread with bias is mainly a result from a decrease in the accelerating field near the cathode surface. Furthermore, simulations reveal that the temporal dispersion is also influenced by the intrinsic angular distribution in the photoemission process and the initial energy spread. However, a smaller emission spot on the cathode is not a dominant driver for enhancing time resolution. Space charge induced temporal broadening shows a close to

A 7.8 kV nanosecond pulse generator with a 500 Hz repetition rate

Science.gov (United States)

Lin, M.; Liao, H.; Liu, M.; Zhu, G.; Yang, Z.; Shi, P.; Lu, Q.; Sun, X.

2018-04-01

Pseudospark switches are widely used in pulsed power applications. In this paper, we present the design and performance of a 500 Hz repetition rate high-voltage pulse generator to drive TDI-series pseudospark switches. A high-voltage pulse is produced by discharging an 8 μF capacitor through a primary windings of a setup isolation transformer using a single metal-oxide-semiconductor field-effect transistor (MOSFET) as a control switch. In addition, a self-break spark gap is used to steepen the pulse front. The pulse generator can deliver a high-voltage pulse with a peak trigger voltage of 7.8 kV, a peak trigger current of 63 A, a full width at half maximum (FWHM) of ~30 ns, and a rise time of 5 ns to the trigger pin of the pseudospark switch. During burst mode operation, the generator achieved up to a 500 Hz repetition rate. Meanwhile, we also provide an AC heater power circuit for heating a H2 reservoir. This pulse generator can be used in circuits with TDI-series pseudospark switches with either a grounded cathode or with a cathode electrically floating operation. The details of the circuits and their implementation are described in the paper.

A centre-triggered magnesium fuelled cathodic arc thruster uses sublimation to deliver a record high specific impulse

Science.gov (United States)

Neumann, Patrick R. C.; Bilek, Marcela; McKenzie, David R.

2016-08-01

The cathodic arc is a high current, low voltage discharge that operates in vacuum and provides a stream of highly ionised plasma from a solid conducting cathode. The high ion velocities, together with the high ionisation fraction and the quasineutrality of the exhaust stream, make the cathodic arc an attractive plasma source for spacecraft propulsion applications. The specific impulse of the cathodic arc thruster is substantially increased when the emission of neutral species is reduced. Here, we demonstrate a reduction of neutral emission by exploiting sublimation in cathode spots and enhanced ionisation of the plasma in short, high-current pulses. This, combined with the enhanced directionality due to the efficient erosion profiles created by centre-triggering, substantially increases the specific impulse. We present experimentally measured specific impulses and jet power efficiencies for titanium and magnesium fuels. Our Mg fuelled source provides the highest reported specific impulse for a gridless ion thruster and is competitive with all flight rated ion thrusters. We present a model based on cathode sublimation and melting at the cathodic arc spot explaining the outstanding performance of the Mg fuelled source. A further significant advantage of an Mg-fuelled thruster is the abundance of Mg in asteroidal material and in space junk, providing an opportunity for utilising these resources in space.

Quantitative comparison of 3 enamel-stripping devices in vitro: how precisely can we strip teeth?

Science.gov (United States)

Johner, Alexander Marc; Pandis, Nikolaos; Dudic, Alexander; Kiliaridis, Stavros

2013-04-01

In this in-vitro study, we aimed to investigate the predictability of the expected amount of stripping using 3 common stripping devices on premolars. One hundred eighty extracted premolars were mounted and aligned in silicone. Tooth mobility was tested with Periotest (Medizintechnik Gulden, Modautal, Germany) (8.3 ± 2.8 units). The selected methods for interproximal enamel reduction were hand-pulled strips (Horico, Hapf Ringleb & Company, Berlin, Germany), oscillating segmental disks (O-drive-OD 30; KaVo Dental, Biberach, Germany), and motor-driven abrasive strips (Orthofile; SDC Switzerland, Lugano-Grancia, Switzerland). With each device, the operator intended to strip 0.1, 0.2, 0.3, or 0.4 mm on the mesial side of 15 teeth. The teeth were scanned before and after stripping with a 3-dimensional laser scanner. Superposition and measurement of stripped enamel on the most mesial point of the tooth were conducted with Viewbox software (dHal Software, Kifissia, Greece). The Wilcoxon signed rank test and the Kruskal-Wallis test were applied; statistical significance was set at alpha ≤ 0.05. Large variations between the intended and the actual amounts of stripped enamel, and between stripping procedures, were observed. Significant differences were found at 0.1 mm of intended stripping (P ≤ 0.05) for the hand-pulled method and at 0.4 mm of intended stripping (P ≤ 0.001 to P = 0.05) for all methods. For all scenarios of enamel reduction, the actual amount of stripping was less than the predetermined and expected amount of stripping. The Kruskal-Wallis analysis showed no significant differences between the 3 methods. There were variations in the stripped amounts of enamel, and the stripping technique did not appear to be a significant predictor of the actual amount of enamel reduction. In most cases, actual stripping was less than the intended amount of enamel reduction. Copyright © 2013 American Association of Orthodontists. Published by Mosby, Inc. All rights

Two-dimension multiwire detector for ionizing radiation

International Nuclear Information System (INIS)

Barberino, Carlos Henrique

1993-01-01

A multiwire proportional Counter of 100 x 100 mm 2 sensitive area has been developed. The chamber is formed by three planes: a cathode plane of 50 μm gold coated tungsten wires stretched on an Epoxi frame; and anode plane made of 20 μm gold plated tungsten wires stretched at 45 deg C with respect to the first cathode wires; and second cathode plane made of copper strips on a printed circuit board at 90 deg C with respect to the first cathode. The cathode strips are connected to the taps of delay-lines chips. The position of the incidence of radiation is extracted by measuring the time difference of the pulse arriving at the extremities of the delay-line chain for each coordinate. The performance of the detector has been tested using 5.89 KeV X-rays from a 55 Fe source, and 8.04 KeV from Rigaku X-rays generator, operating the detector with 90% Ar + 10% CH 4 gas mixture at 930 mbar. An energy resolution of 26% was obtained. An integral non linearity better than 0.3% and a position resolution better than 1 mm have been observed. The information corresponding to each one of the coordinates were digitized by a TDC in a CAMAC system and stored event by event in a micro-computer (IBM-AT). (author)

A micro-strip gas counter test with the RD20 front-end

International Nuclear Information System (INIS)

Clergeau, J.F.; Contardo, D.; Haroutunian, R.; Smadja, G.

1994-05-01

A Micro-Strip Gas Counter equipped with the VLSI preamplifier of the RD20 chip has been tested with minimum ionizing particles. The measured pulse shape and the signal to noise ratio are presented. The time resolution of the detector is compared for the Ar/DME and DME/CO 2 gas mixtures. Three methods for the bunch crossing identification at LHC are discussed. (authors). 5 refs., 7 figs., 3 tabs

Determination of transport and reaction swarm coefficients from the analysis of complex transient pulses from the pulsed Townsend experiment

International Nuclear Information System (INIS)

Bekstein, A; De Urquijo, J; Rodríguez-Luna, J C; Juárez, A M; Ducasse, O

2012-01-01

We present in this paper the interpretation and analysis of transient pulses from a pulsed Townsend experiment by solving the continuity equations of the charged carriers (electrons and ions) involved in the avalanche. The set of second order partial differential equations is solved by SIMAV, a simulator designed specifically for the pulsed Townsend avalanche. Complex situations involving processes such as electron detachment, ion-molecule reactions, Penning ionization and secondary electron emission from ion impact at the cathode, virtually impossible to solve analytically, are discussed here to illustrate the capability of the simulator to help explain the various reaction processes involved in the avalanche, and also to derive some of the transport and reaction coefficients.

Observation of Repetition-Rate Dependent Emission From an Un-Gated Thermionic Cathode Rf Gun

Energy Technology Data Exchange (ETDEWEB)

Edelen, J. P.; Sun, Y.; Harris, J.R.; Lewellen, J.W.

2017-06-02

Recent work at Fermilab in collaboration with the Advanced Photon Source and members of other national labs, designed an experiment to study the relationship between the RF repetition rate and the average current per RF pulse. While existing models anticipate a direct relationship between these two parameters we observed an inverse relationship. We believe this is a result of damage to the barium coating on the cathode surface caused by a change in back-bombardment power that is unaccounted for in the existing theories. These observations shed new light on the challenges and fundamental limitations associated with scaling an ungated thermionic cathode RF gun to high average current.

Stripping Voltammetry

Science.gov (United States)

Lovrić, Milivoj

Electrochemical stripping means the oxidative or reductive removal of atoms, ions, or compounds from an electrode surface (or from the electrode body, as in the case of liquid mercury electrodes with dissolved metals) [1-5]. In general, these atoms, ions, or compounds have been preliminarily immobilized on the surface of an inert electrode (or within it) as the result of a preconcentration step, while the products of the electrochemical stripping will dissolve in the electrolytic solution. Often the product of the electrochemical stripping is identical to the analyte before the preconcentration. However, there are exemptions to these rules. Electroanalytical stripping methods comprise two steps: first, the accumulation of a dissolved analyte onto, or in, the working electrode, and, second, the subsequent stripping of the accumulated substance by a voltammetric [3, 5], potentiometric [6, 7], or coulometric [8] technique. In stripping voltammetry, the condition is that there are two independent linear relationships: the first one between the activity of accumulated substance and the concentration of analyte in the sample, and the second between the maximum stripping current and the accumulated substance activity. Hence, a cumulative linear relationship between the maximum response and the analyte concentration exists. However, the electrode capacity for the analyte accumulation is limited and the condition of linearity is satisfied only well below the electrode saturation. For this reason, stripping voltammetry is used mainly in trace analysis. The limit of detection depends on the factor of proportionality between the activity of the accumulated substance and the bulk concentration of the analyte. This factor is a constant in the case of a chemical accumulation, but for electrochemical accumulation it depends on the electrode potential. The factor of proportionality between the maximum stripping current and the analyte concentration is rarely known exactly. In fact

Electron emission and plasma generation in a modulator electron gun using ferroelectric cathode

International Nuclear Information System (INIS)

Chen Shutao; Zheng Shuxin; Zhu Ziqiu; Dong Xianlin; Tang Chuanxiang

2006-01-01

Strong electron emission and dense plasma generation have been observed in a modulator electron gun with a Ba 0.67 Sr 0.33 TiO 3 ferroelectric cathode. Parameter of the modulator electron gun and lifetime of the ferroelectric cathode were investigated. It was shown that electron emission from Ba 0.67 Sr 0.33 TiO 3 cathode with a positive triggering pulse is a sort of plasma emission. Electrons were emitted by the co-effect of surface plasma and non-compensated negative polarization charges at the surface of the ferroelectric. The element analyses of the graphite collector after emission process was performed to show the ingredient of the plasma consist of Ba, Ti and Cu heavy cations of the ceramic compound and electrode. It was demonstrated the validity of the Child-Langmuir law by introducing the decrease of vacuum gap and increase of emission area caused by the expansion of the surface plasma

Multiplex Outputs ns Grade High-voltage Fast Pulse Generator Study

International Nuclear Information System (INIS)

Wang Xin; Chen Kenan

2009-01-01

Using a double-grid hydrogen thyratron, a fast pulse generator with four outputs, high-voltage, low jitter, was made to use at special occasion.In this paper, the basic structure of pulser, switching theory and double-grid driving of hydrogen thyratron was introduced, and also, the effects of grids driving pulses characteristics, the delay between too grids driving, the reservoir heater voltage and cathode heater voltage on the output are carefully examined in experiments. The pulse generator with four outputs was made to producing pulses with amplitude up to 4 kV, rise-time less than 15 ns and jitter less than 3 ns. (authors)

Fast pulse beam generation systems for electron accelerators

International Nuclear Information System (INIS)

Koontz, R.F.

1977-01-01

The fast pulse beam generation system to supply the SLAC storage ring, SPEAR, by the two one nanosecond bunch electron beam pulses is described. Generation of these pulses is accomplished with a combination of a fast pulsed grided gun and a synchronized transverse beam chopper. Fast gun based on spherical cathode-grid assembly has output current up to 2As. Fast pulse amplifier system can handle trains of short pulses with repetition rates up to 40 MHz during the 1.6 μs normal accelerating time. Chopping deflector system consists of a resonant coaxial line with the deflecting plates. The resonator frequency is 39.667 MHz. A schematic diagram of the resonant system is shown. The fast beam pickup system has a one hundred picosecond rise time overrall. Fast beam generation and chopper systems permit to generate almost any short or single bunch beam profile needed for experiments

Monophasic Pulsed 200-μA Current Promotes Galvanotaxis With Polarization of Actin Filament and Integrin α2β1 in Human Dermal Fibroblasts.

Science.gov (United States)

Uemura, Mikiko; Maeshige, Noriaki; Koga, Yuka; Ishikawa-Aoyama, Michiko; Miyoshi, Makoto; Sugimoto, Masaharu; Terashi, Hiroto; Usami, Makoto

2016-01-01

The monophasic pulsed microcurrent is used to promote wound healing, and galvanotaxis regulation has been reported as one of the active mechanisms in the promotion of tissue repair with monophasic pulsed microcurrent. However, the optimum monophasic pulsed microcurrent parameters and intracellular changes caused by the monophasic pulsed microcurrent have not been elucidated in human dermal fibroblasts. The purpose of this study was to investigate the optimum intensity for promoting galvanotaxis and the effects of electrical stimulation on integrin α2β1 and actin filaments in human dermal fibroblasts. Human dermal fibroblasts were treated with the monophasic pulsed microcurrent of 0, 100, 200, or 300 μA for 8 hours, and cell migration and cell viability were measured 24 hours after starting monophasic pulsed microcurrent stimulation. Polarization of integrin α2β1 and lamellipodia formation were detected by immunofluorescent staining 10 minutes after starting monophasic pulsed microcurrent stimulation. The migration toward the cathode was significantly higher in the cells treated with the 200-μA monophasic pulsed microcurrent than in the controls (P microcurrent did not alter the migration ratio. The electrostimulus of 200 μA also promoted integrin α2β1 polarization and lamellipodia formation at the cathode edge (P microcurrent intensity to promote migration toward the cathode, and this intensity could regulate polarization of migration-related intracellular factors in human dermal fibroblasts.

Analysis of cathode geometry to minimize cathode erosion in direct current microplasma jet

Energy Technology Data Exchange (ETDEWEB)

Causa, Federica [Dipartimento di Scienze dell' Ambiente, della Sicurezza, del Territorio, degli Alimenti e della Salute, Universita degli studi di Messina, 98122 Messina (Italy); Ghezzi, Francesco; Caniello, Roberto; Grosso, Giovanni [Istituto di Fisica del Plasma, Consiglio Nazionale delle Ricerche, EURATOM-ENEA-CNR Association, Via R. Cozzi 53, 20125 Milano (Italy); Dellasega, David [Istituto di Fisica del Plasma, Consiglio Nazionale delle Ricerche, EURATOM-ENEA-CNR Association, Via R. Cozzi 53, 20125 Milano (Italy); Dipartimento di Energia, Politecnico di Milano, Via Ponzio 34/3, 20133 Milano (Italy)

2012-12-15

Microplasma jets are now widely used for deposition, etching, and materials processing. The present study focuses on the investigation of the influence of cathode geometry on deposition quality, for microplasma jet deposition systems in low vacuum. The interest here is understanding the influence of hydrogen on sputtering and/or evaporation of the electrodes. Samples obtained with two cathode geometries with tapered and rectangular cross-sections have been investigated experimentally by scanning electron microscopy and energy dispersion X-ray spectroscopy. Samples obtained with a tapered-geometry cathode present heavy contamination, demonstrating cathode erosion, while samples obtained with a rectangular-cross-section cathode are free from contamination. These experimental characteristics were explained by modelling results showing a larger radial component of the electric field at the cathode inner wall of the tapered cathode. As a result, ion acceleration is larger, explaining the observed cathode erosion in this case. Results from the present investigation also show that the ratio of radial to axial field components is larger for the rectangular geometry case, thus, qualitatively explaining the presence of micro-hollow cathode discharge over a wide range of currents observed in this case. In the light of the above findings, the rectangular cathode geometry is considered to be more effective to achieve cleaner deposition.

Application of different methodologies in the preparation of organic matrices for determination of trace elements by differential pulse anodic stripping voltammetry

International Nuclear Information System (INIS)

Sisti, Cristina

2001-01-01

The determination of trace elements in food samples is of great importance for the human health, considering the factors of essentiality and toxicity. On the other hand, the chemical analysis is largely affected for the steps of sample preparation; laboratory contamination of the sample and the reagents or still volatilization and losses of the elements. If these parameters are not controlled the achieved precision and accuracy could be low. In this work, the content of zinc, cadmium, lead and copper was determined in adults diet samples collected by duplicate portion technique and bovine liver, applying the differential pulse anodic stripping voltametry - (DP-ASV) technique. In the digestion of the matrices in acid medium, conventional methodologies were used, conductive heating in open recipients and equipment with microwaves source in open and closed vessels. The best procedure was the sample digestion by microwaves, in closed vessels and the other treatments made in controlled atmosphere with hood laminar-airflow class 100. The established methodology was validated with the use of a certified sample as reference (NIST - bovine liver 1577b). (author)

A digital X-ray imaging system based on silicon strip detectors working in edge-on configuration

Energy Technology Data Exchange (ETDEWEB)

Bolanos, L. [CEADEN, Calle 30 502 e/ 5ta y 7ma Avenida, Playa, Ciudad Habana (Cuba); Boscardin, M. [IRST, Fondazione Bruno Kessler, Via Sommarive 18, Povo, 38100 Trento (Italy); Cabal, A.E. [CEADEN, Calle 30 502 e/ 5ta y 7ma Avenida, Playa, Ciudad Habana (Cuba); Diaz, M. [InSTEC, Ave. Salvador Allende esq. Luaces, Quinta de los Molinos, Ciudad Habana (Cuba); Grybos, P.; Maj, P. [Faculty of Electrical Engineering, Automatics, Computer Science and Electronics, Department of Measurement and Instrumentation, AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Cracow (Poland); Prino, F. [Istituto Nazionale di Fisica Nucleare, Sezione di Torino, Via P. Giuria 1, 10125 Torino (Italy); Ramello, L. [Dipartimento di Scienze e Tecnologie Avanzate, Universita del Piemonte Orientale, Via T. Michel 11, 15100 Alessandria (Italy)], E-mail: luciano.ramello@mfn.unipmn.it; Szczygiel, R. [Faculty of Electrical Engineering, Automatics, Computer Science and Electronics, Department of Measurement and Instrumentation, AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Cracow (Poland)

2009-09-21

We present the energy resolution and imaging performance of a digital X-ray imaging system based on a 512-strip silicon strip detector (SSD) working in the edge-on configuration. The SSDs tested in the system are 300 {mu}m thick with 1 or 2-cm-long strips and 100 {mu}m pitch. To ensure a very small dead area of the SSD working in edge-on configuration, the detector is cut perpendicular to the strips at a distance of only 20 {mu}m from the end of the strips. The 512-strip silicon detector is read out by eight 64-channel integrated circuits called DEDIX [Grybos et al., IEEE Trans. Nucl. Sci. NS-54 (2007) 1207]. The DEDIX IC operates in a single photon counting mode with two independent amplitude discriminators per channel. The readout electronic channel connected to a detector with effective input capacitance of about 2 pF has an average equivalent noise charge (ENC) of about 163 el. rms and is able to count 1 Mcps of average rate of input pulses. The system consisting of 512 channels has an excellent channel-to-channel uniformity-the effective threshold spread calculated to the charge-sensitive amplifier inputs is 12 el. rms (at one sigma level). With this system a few test images of a phantom have been taken in the 10-30 keV energy range.

Experimental research on a double pulsed beam source

International Nuclear Information System (INIS)

Xia Liansheng; Zhang Linwen; Huang Ziping; Gao Feng; Shi Jinshui; Deng Jianjun

2004-01-01

A double pulsed beam generator is built based on 2 MeV linear induction accelerator (LIA) injector. The second power source and 8 inductive cells of the injector are divided into two groups and work alternatively. Electron energy of each beam is up to 1 MeV and the beam duration is 120 ns with adjustable pulse interval (from 200 ns to 800 ns). The voltage amplitude difference of the two pulses can be less than 2%. The electron beams are emitted from a velvet cathode in a vacuum diode. The beam currents are up to 3 kA, measured both by a Faraday cup in anode hole and by a shunt resistor at the rail of the LIA injector. This device can be used to study multi-pulse diode physics and emitting physics of different materials under multi-pulse mode. (author)

MUST: A silicon strip detector array for radioactive beam experiments

International Nuclear Information System (INIS)

Blumenfeld, Y.; Auger, F.; Sauvestre, J.E.; Marechal, F.; Ottini, S.; Alamanos, N.; Barbier, A.; Beaumel, D.; Bonnereau, B.; Charlet, D.; Clavelin, J.F.; Courtat, P.; Delbourgo-Salvador, P.; Douet, R.; Engrand, M.; Ethvignot, T.; Gillibert, A.; Khan, E.; Lapoux, V.; Lagoyannis, A.; Lavergne, L.; Lebon, S.; Lelong, P.; Lesage, A.; Le Ven, V.; Lhenry, I.; Martin, J.M.; Musumarra, A.; Pita, S.; Petizon, L.; Pollacco, E.; Pouthas, J.; Richard, A.; Rougier, D.; Santonocito, D.; Scarpaci, J.A.; Sida, J.L.; Soulet, C.; Stutzmann, J.S.; Suomijaervi, T.; Szmigiel, M.; Volkov, P.; Voltolini, G.

1999-01-01

A new and innovative array, MUST, based on silicon strip technology and dedicated to the study of reactions induced by radioactive beams on light particles is described. The detector consists of 8 silicon strip - Si(Li) telescopes used to identify recoiling light charged particles through time of flight, energy loss and energy measurements and to determine precisely their scattering angle through X, Y position measurements. Each 60x60 mm 2 double sided silicon strip detector with 60 vertical and 60 horizontal strips yields an X-Y position resolution of 1 mm, an energy resolution of 50 keV, a time resolution of around 1 ns and a 500 keV energy threshold for protons. The backing Si(Li) detectors stop protons up to 25 MeV with a resolution of approximately 50 keV. CsI crystals read out by photo-diodes which stop protons up to 70 MeV are added to the telescopes for applications where higher energy particles need to be detected. The dedicated electronics in VXIbus standard allow us to house the 968 logic and analog channels of the array in one crate placed adjacent to the reaction chamber and fully remote controlled, including pulse visualization on oscilloscopes. A stand alone data acquisition system devoted to the MUST array has been developed. Isotope identification of light charged particles over the full energy range has been achieved, and the capability of the system to measure angular distributions of states populated in inverse kinematics reactions has been demonstrated

Effect of secondary electron emission on subnanosecond breakdown in high-voltage pulse discharge

Science.gov (United States)

Schweigert, I. V.; Alexandrov, A. L.; Gugin, P.; Lavrukhin, M.; Bokhan, P. A.; Zakrevsky, Dm E.

2017-11-01

The subnanosecond breakdown in open discharge may be applied for producing superfast high power switches. Such fast breakdown in high-voltage pulse discharge in helium was explored both in experiment and in kinetic simulations. The kinetic model of electron avalanche development was developed using PIC-MCC technique. The model simulates motion of electrons, ions and fast helium atoms, appearing due to ions scattering. It was shown that the mechanism responsible for ultra-fast breakdown development is the electron emission from cathode. The photoemission and emission by ions or fast atoms impact is the main reason of current growth at the early stage of breakdown, but at the final stage, when the voltage on discharge gap drops, the secondary electron emission (SEE) is responsible for subnanosecond time scale of current growth. It was also found that the characteristic time of the current growth τS depends on the SEE yield of the cathode material. Three types of cathode material (titanium, SiC, and CuAlMg-alloy) were tested. It is shown that in discharge with SiC and CuAlMg-alloy cathodes (which have enhanced SEE) the current can increase with a subnanosecond characteristic time as small as τS = 0.4 ns, for the pulse voltage amplitude of 5- 12 kV..

Design of long pulse/steady state negative hydrogen ion sources for fusion applications

International Nuclear Information System (INIS)

Prelec, K.

1980-01-01

By using parameters of ion sources when operating in a pulsed mode and without cooling (pulse length 2 . For the range of cathode power densities between 0.2 kW/cm 2 and 1 Kw/cm 2 , nucleated boiling has to be used for heat removal; below 0.2 kW/cm 2 water flow cooling suffices. Although this source should deliver 0.3 to 0.5 A of H - ions in a steady state operation and at full power, the other source, which has a magnetron geometry, is more promising. The latter incorporates two new features compared to first designs, geometrical focusing of fast, primary negative hydrogen ions from the cathode into the extraction slit, and a wider discharge gap in the back of the source. These two changes have resulted in an improvement of the power and gas efficiencies by a factor of 3 to 4 and in a reduction of the cathode power density by an order of magnitude. The source has water cooling for all the electrodes, because maximum power densities will not be higher than 0.2 kW/cm 2 . Very recently a modification of this magnetron source is being considered; it consists of plasma injection into the source from a hollow cathode discharge

Depression cathode structure for cathode ray tubes having surface smoothness and method for producing same

International Nuclear Information System (INIS)

Rychlewski, T.V.

1984-01-01

Depression cathode structures for cathode ray tubes are produced by dispensing liquid cathode material into the depression of a metallic supporting substrate, removing excess cathode material by passing a doctor blade across the substrate surface and over the depression, and drying the cathode layer to a substantially immobile state. The cathode layer may optionally be further shaped prior to substantially complete drying thereof

Water-dielectric-breakdown relation for the design of large-area multimegavolt pulsed-power systems

Directory of Open Access Journals (Sweden)

W. A. Stygar

2006-07-01

Full Text Available We have developed an empirical electrical-breakdown relation that can be used to design large-area water-insulated pulsed-power systems. Such systems often form an integral part of multiterawatt pulsed-power accelerators, and may be incorporated in future petawatt-class machines. We find that complete dielectric failure is likely to occur in water between a significantly field-enhanced anode and a less-enhanced cathode when E_{p}τ_{eff}^{0.330±0.026}=0.135±0.009. In this expression E_{p}≡V_{p}/d is the peak value in time of the spatially averaged electric field between the anode and cathode (in MV/cm, V_{p} is the peak voltage across the electrodes, d is the distance between the anode and cathode, and τ_{eff} is the temporal width (in μs of the voltage pulse at 63% of peak. This relation is based on 25 measurements for which 1≤V_{p}≤4.10   MV, 1.25≤d≤22   cm, and 0.011≤τ_{eff}≤0.6   μs. The normalized standard deviation of the differences between these measurements and the associated predictions of the relation is 12%.

Magnetic pulse compression circuits for plasma devices

Energy Technology Data Exchange (ETDEWEB)

Georgescu, N; Zoita, V; Presura, R [Inst. of Physics and Technology of Radiation Devices, Bucharest (Romania)

1997-12-31

Two magnetic pulse compression circuits (MPCC), for two different plasma devices, are presented. The first is a 20 J/pulse, 3-stage circuit designed to trigger a low pressure discharge. The circuit has 16-18 kV working voltage, and 200 nF in each stage. The saturable inductors are realized with toroidal 25 {mu}m strip-wound cores, made of a Fe-Ni alloy, with 1.5 T saturation induction. The total magnetic volume is around 290 cm{sup 3}. By using a 25 kV/1 A thyratron as a primary switch, the time compression is from 3.5 {mu}s to 450 ns, in a short-circuit load. The second magnetic pulser is a 200 J/pulse circuit, designed to drive a high average power plasma focus soft X-ray source, for X-ray microlithography as the main application. The 3-stage pulser should supply a maximum load current of 100 kA with a rise-time of 250 - 300 ns. The maximum pulse voltage applied on the plasma discharge chamber is around 20 - 25 kV. The three saturable inductors in the circuit are made of toroidal strip-wound cores with METGLAS 2605 CO amorphous alloy as the magnetic material. The total, optimized mass of the magnetic material is 34 kg. The maximum repetition rate is limited at 100 Hz by the thyratron used in the first stage of the circuit, the driver supplying to the load about 20 kW average power. (author). 1 tab., 3 figs., 3 refs.

Pulsed power accelerator for material physics experiments

Directory of Open Access Journals (Sweden)

D. B. Reisman

2015-09-01

Full Text Available We have developed the design of Thor: a pulsed power accelerator that delivers a precisely shaped current pulse with a peak value as high as 7 MA to a strip-line load. The peak magnetic pressure achieved within a 1-cm-wide load is as high as 100 GPa. Thor is powered by as many as 288 decoupled and transit-time isolated bricks. Each brick consists of a single switch and two capacitors connected electrically in series. The bricks can be individually triggered to achieve a high degree of current pulse tailoring. Because the accelerator is impedance matched throughout, capacitor energy is delivered to the strip-line load with an efficiency as high as 50%. We used an iterative finite element method (FEM, circuit, and magnetohydrodynamic simulations to develop an optimized accelerator design. When powered by 96 bricks, Thor delivers as much as 4.1 MA to a load, and achieves peak magnetic pressures as high as 65 GPa. When powered by 288 bricks, Thor delivers as much as 6.9 MA to a load, and achieves magnetic pressures as high as 170 GPa. We have developed an algebraic calculational procedure that uses the single brick basis function to determine the brick-triggering sequence necessary to generate a highly tailored current pulse time history for shockless loading of samples. Thor will drive a wide variety of magnetically driven shockless ramp compression, shockless flyer plate, shock-ramp, equation of state, material strength, phase transition, and other advanced material physics experiments.

High current density M-type cathodes for vacuum electron devices

International Nuclear Information System (INIS)

Li Ji; Yu Zhiqiang; Shao Wensheng; Zhang Ke; Gao Yujuan; Yuan Haiqing; Wang Hui; Huang Kaizhi; Chen Qilue; Yan Suqiu; Cai Shaolun

2005-01-01

We investigated high current density emission capabilities of M-type cathodes used for vacuum electron devices (VEDs). The experimental results of emission and lifetime evaluating in both close-spaced diode structure and electron gun testing vehicles are given. Emission current densities measured in the diode structure at 1020 deg. C Br in the CW mode were above 10 A/cm 2 ; while in electron gun testing vehicles, emission current densities were above 8 A/cm 2 in CW mode and above 32 A/cm 2 in pulsed mode, respectively. The current density above 94 A/cm 2 has been acquired in no. 0306 electron gun vehicle while the practical temperature is 1060 deg. C Br . For a comparison some of the data from I-scandate cathodes are presented. Finally, several application examples in practical travelling wave tubes (TWTs) and multi beam klystrons (MBKs) are also reported

Varicose vein stripping

Science.gov (United States)

... stripping; Venous reflux - vein stripping; Venous ulcer - veins Patient Instructions Surgical wound care - open Varicose veins - what to ask your doctor Images Circulatory system References American Family Physician. Management of varicose veins. www.aafp.org/afp/2008/ ...

Construction of double discharge pulsed electron beam generator and its applications

International Nuclear Information System (INIS)

Goektas, H.

2001-12-01

Generation of fast pulsed electron beam by superposing DC and pulsed hollow cathode discharge is studied. The electrical characteristics and measurements of the electron beam generator are done dc glow discharge and for the pulsed one. The electron beam current, its density and magnetic field effect, pinch effect, have been studied. The dependence of the electron beam parameters with respect to pressure and magnetic field have been studied. The pulsing effect of the beam is reviewed. By using the generator, micron holes drilling and carbon deposition was done at the laboratory. As a target source for carbon deposition methane gas is used and for Hydrogen-free carbon deposition was graphite

Testbeam evaluation of silicon strip modules for ATLAS Phase - II Strip Tracker Upgrade

CERN Document Server

Blue, Andrew; The ATLAS collaboration; Ai, Xiaocong; Allport, Phillip; Arling, Jan-Hendrik; Atkin, Ryan Justin; Bruni, Lucrezia Stella; Carli, Ina; Casse, Gianluigi; Chen, Liejian; Chisholm, Andrew; Cormier, Kyle James Read; Cunningham, William Reilly; Dervan, Paul; Diez Cornell, Sergio; Dolezal, Zdenek; Dopke, Jens; Dreyer, Etienne; Dreyling-Eschweiler, Jan Linus Roderik; Escobar, Carlos; Fabiani, Veronica; Fadeyev, Vitaliy; Fernandez Tejero, Javier; Fleta Corral, Maria Celeste; Gallop, Bruce; Garcia-Argos, Carlos; Greenall, Ashley; Gregor, Ingrid-Maria; Greig, Graham George; Guescini, Francesco; Hara, Kazuhiko; Hauser, Marc Manuel; Huang, Yanping; Hunter, Robert Francis Holub; Keller, John; Klein, Christoph; Kodys, Peter; Koffas, Thomas; Kotek, Zdenek; Kroll, Jiri; Kuehn, Susanne; Lee, Steven Juhyung; Liu, Yi; Lohwasser, Kristin; Meszarosova, Lucia; Mikestikova, Marcela; Mi\\~nano Moya, Mercedes; Mori, Riccardo; Moser, Brian; Nikolopoulos, Konstantinos; Peschke, Richard; Pezzullo, Giuseppe; Phillips, Peter William; Poley, Anne-luise; Queitsch-Maitland, Michaela; Ravotti, Federico; Rodriguez Rodriguez, Daniel

2018-01-01

The planned HL-LHC (High Luminosity LHC) is being designed to maximise the physics potential of the LHC with 10 years of operation at instantaneous luminosities of \\mbox{$7.5\\times10^{34}\\;\\mathrm{cm}^{-2}\\mathrm{s}^{-1}$}. A consequence of this increased luminosity is the expected radiation damage requiring the tracking detectors to withstand hadron equivalences to over $1x10^{15}$ 1 MeV neutron equivalent per $cm^{2}$ in the ATLAS Strips system. The silicon strip tracker exploits the concept of modularity. Fast readout electronics, deploying 130nm CMOS front-end electronics are glued on top of a silicon sensor to make a module. The radiation hard n-in-p micro-strip sensors used have been developed by the ATLAS ITk Strip Sensor collaboration and produced by Hamamatsu Photonics. A series of tests were performed at the DESY-II test beam facility to investigate the detailed performance of a strip module with both 2.5cm and 5cm length strips before irradiation. The DURANTA telescope was used to obtain a pointing...

Measurement of the dynamic response of low-gain solid-state photodetector under weak pulse illumination

CERN Document Server

Clément, D; Morel, Christian

2000-01-01

This paper presents the development of a Tunable Light Pulse Generator built to measure the quantum efficiency of photodetectors under continuous or pulsed (20 ns FWHM) illumination as a function of wavelength in the Visible-UV region. For this purpose, a miniature Hamamatsu R5600U-04 PMT with low cathode resistivity can be used as reference detector. Dedicated electronics was developed in order to measure simultaneously the cathode and anode currents. This should allow to determine precisely the gain as a function of the high voltage applied to the PMT. Preliminary measurements using the TLPG do not demonstrate significant differences between the dynamic (approx 10 000 photons) and DC responses of PIN photodiodes down to 300 nm.

Compatibility of a Conventional Non-aqueous Magnesium Electrolyte with a High Voltage V₂O₅ Cathode and Mg Anode

Energy Technology Data Exchange (ETDEWEB)

Sa, Niya [Argonne National Lab. (ANL), Argonne, IL (United States); Proffit, Danielle L. [Argonne National Lab. (ANL), Argonne, IL (United States); Lipson, Albert L. [Argonne National Lab. (ANL), Argonne, IL (United States); Liu, Miao [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Gautam, Gopalakrishnan Sai [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Hahn, Nathan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Feng, Zhenxing [Argonne National Lab. (ANL), Argonne, IL (United States); Fister, Timothy T. [Argonne National Lab. (ANL), Argonne, IL (United States); Ren, Yang [Argonne National Lab. (ANL), Argonne, IL (United States); Sun, Cheng-Jun [Argonne National Lab. (ANL), Argonne, IL (United States); Vaughey, John T. [Argonne National Lab. (ANL), Argonne, IL (United States); Liao, Chen [Argonne National Lab. (ANL), Argonne, IL (United States); Fenter, Paul A. [Argonne National Lab. (ANL), Argonne, IL (United States); Ceder, Gerbrand [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Zavadil, Kevin R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Burrell, Anthony K. [Argonne National Lab. (ANL), Argonne, IL (United States)

2015-08-01

A major roadblock for magnesium ion battery development is the availability of an electrolyte that can deposit Mg reversibly and at the same time is compatible with a high voltage cathode. We report a prospective full magnesium cell utilizing a simple, non-aqueous electrolyte composed of high concentration magnesium bis(trifluoromethane sulfonyl)imide in diglyme, which is compatible with a high voltage vanadium pentoxide (V₂O₅) cathode and a Mg metal anode. For this system, plating and stripping of Mg metal can be achieved with magnesium bis(trifluoromethane sulfonyl)imide in diglyme electrolyte over a wide concentration range, however, reversible insertion of Mg into V₂O₅ cathode can only be attained at high electrolyte concentrations. Reversible intercalation of Mg into V₂O₅ is characterized and confirmed by X-ray diffraction, X-ray absorption near edge spectroscopy and energy dispersive spectroscopy.

'Quasi-plasma' transport model in deuterium overloaded palladium cathodes

International Nuclear Information System (INIS)

Ninno, A. de; Violante, V.

1993-01-01

The Pd-D system has been described assuming a two-population model. A 'quasi-plasma' delocalized boson gas picture has been used for the deuterons exceeding the stoichiometric ratio in Pd-D compounds. A mathematical model supported by a numerical computer code with distributed parameters has been developed in order to describe the evolution of the deuteron concentration profile inside a Pd cathode under pulsed electrolysis. Several boundary conditions have been taken into account. A strong correlation has been found between the model system evolution and the experimental data. (author)

Development of an ion source for long-pulse (30-s) neutral beam injection

International Nuclear Information System (INIS)

Menon, M.M.; Barber, G.C.; Blue, C.W.

1982-01-01

This paper describes the development of a long-pulse positive ion source that has been designed to provide high brightness deuterium beams (divergence approx. = 0.25 0 rms, current density approx. = 0.15 A cm -2 ) of 40 to 45 A, at a beam energy of 80 keV, for pulse lengths up to 30 s. The design and construction of the ion source components are described with particular emphasis placed on the long-pulse cathode assembly and ion accelerator

Ionization Waves in a Fast, Hollow-Cathode-Assisted Capillary Discharge

International Nuclear Information System (INIS)

Rutkevich, I.; Mond, M.; Kaufman, Y.; Choi, P.; Favre, M.

1999-01-01

The initial, low-current stage of the evolution of a soft x-ray emitting, hollow-cathode-assisted capillary discharge initiated by a steep high-voltage pulse is investigated. The capillary is surrounded by a shield having the cathode potential. The mean electric field E of the order of 10 kV/cm and the low gas pressure (P<1Torr) provide conditions for extensive electron runaway. This is taken into account in the formulation of the theoretical approach by retaining the inertial terms in the momentum equation for the electrons. In addition, the ionization rate is calculated by considering the cross section for ionization by high-energy electrons. The two-dimensional system of the basic equations is reduced to a system of one-dimensional equations for the axial distributions of the physical quantities by introducing appropriate radial profiles of the electric potential, and the electron gas parameters and satisfying the electrodynamic boundary conditions at the capillary wall and at the shield. The resulting system of equations admits solutions in the form of stationary ionization waves transferring the anode potential to the cathode end. Numerical calculations of such solutions for argon show that the wave velocity V increases with the gas pressure P and with the density of initial electron beam ejected from the cathode hole ahead of the ionization front, while the dependence of V on the applied voltage is weak. At the instant when the virtual anode reaches the cathode hole, the plasma in the capillary is not yet fully ionized. The traverse time of the ionization wave along the capillary calculated for various gas pressures is in reasonable agreement with experimentally registered time delay for a high-current stage resulting in voltage collapse and soft x-ray emission

Laser optogalvanic wavelength calibration with a commercial hollow cathode iron - neon discharge lamp

Science.gov (United States)

Zhu, Xinming; Nur, Abdullahi H.; Misra, Prabhakar

1994-01-01

351 optogalvanic transitions have been observed in the 337 - 598 nm wavelength region using an iron - neon hollow cathode discharge lamp and a pulsed tunable dye laser. 223 of these have been identified as transitions associated with neon energy levels. These optogalvanic transitions have allowed, in conjunction with interference fringes recorded concomitantly with an etalon, the calibration of the dye laser wavelength with 0.3/cm accuracy.

Pulsed electron accelerator for radiation technologies in the enviromental applications

Science.gov (United States)

Korenev, Sergey

1997-05-01

The project of pulsed electron accelerator for radiation technologies in the environmental applications is considered. An accelerator consists of high voltage generator with vacuum insulation and vacuum diode with plasma cathode on the basis discharge on the surface of dielectric of large dimensions. The main parameters of electron accelerators are following: kinetic energy 0.2 - 2.0 MeV, electron beam current 1 - 30 kA and pulse duration 1- 5 microseconds. The main applications of accelerator for decomposition of wastewaters are considered.

High current photoemission with 10 picosecond uv pulses

International Nuclear Information System (INIS)

Fischer, J.; Srinivasan-Rao, T.; Tsang, T.

1990-06-01

The quantum efficiency and the optical damage threshold of various metals were explored with 10 ps, 266 nm, UV laser pulses. Efficiencies for Cu, Y, and Sm were: 1.4, 5, and 7 x 10 -4 , with damage thresholds about 100, 10, and 30 mJ/cm 2 . This would permit over 1 μC/cm 2 or current densities exceeding 100 kA/cm 2 . High charge and current densities of up to 66 kA/cm 2 were obtained on 0.25 mm diam cathodes, and 21 kA/cm 2 on a 3 mm diam yttrium cathode. The maximum currents were limited by space charge and the dc field. The experiments with small area illumination indicate that the emitted electrons spread transversely due to Coulomb repulsion and their initial transverse velocity. This increases the effective area above the cathode, reduces the space charge effect and increases emission density on the cathode. The quantum efficiency can be increased substantially by enhancing the field on the surface by either a suitable electrode geometry or microstructures on it. 14 refs., 12 figs., 3 tabs

Two-dimension multiwire detector for ionizing radiation; Detector multifilar bidimensional para radiacao ionizante

Energy Technology Data Exchange (ETDEWEB)

Barberino, Carlos Henrique

1994-12-31

A multiwire proportional Counter of 100 x 100 mm{sup 2} sensitive area has been developed. The chamber is formed by three planes: a cathode plane of 50 {mu}m gold coated tungsten wires stretched on an Epoxi frame; and anode plane made of 20 {mu}m gold plated tungsten wires stretched at 45 deg C with respect to the first cathode wires; and second cathode plane made of copper strips on a printed circuit board at 90 deg C with respect to the first cathode. The cathode strips are connected to the taps of delay-lines chips. The position of the incidence of radiation is extracted by measuring the time difference of the pulse arriving at the extremities of the delay-line chain for each coordinate. The performance of the detector has been tested using 5.89 KeV X-rays from a {sup 55} Fe source, and 8.04 KeV from Rigaku X-rays generator, operating the detector with 90% Ar + 10% CH{sub 4} gas mixture at 930 mbar. An energy resolution of 26% was obtained. An integral non linearity better than 0.3% and a position resolution better than 1 mm have been observed. The information corresponding to each one of the coordinates were digitized by a TDC in a CAMAC system and stored event by event in a micro-computer (IBM-AT). (author) 56 refs., 68 figs.

Two-dimension multiwire detector for ionizing radiation; Detector multifilar bidimensional para radiacao ionizante

Energy Technology Data Exchange (ETDEWEB)

Barberino, Carlos Henrique

1993-12-31

A multiwire proportional Counter of 100 x 100 mm{sup 2} sensitive area has been developed. The chamber is formed by three planes: a cathode plane of 50 {mu}m gold coated tungsten wires stretched on an Epoxi frame; and anode plane made of 20 {mu}m gold plated tungsten wires stretched at 45 deg C with respect to the first cathode wires; and second cathode plane made of copper strips on a printed circuit board at 90 deg C with respect to the first cathode. The cathode strips are connected to the taps of delay-lines chips. The position of the incidence of radiation is extracted by measuring the time difference of the pulse arriving at the extremities of the delay-line chain for each coordinate. The performance of the detector has been tested using 5.89 KeV X-rays from a {sup 55} Fe source, and 8.04 KeV from Rigaku X-rays generator, operating the detector with 90% Ar + 10% CH{sub 4} gas mixture at 930 mbar. An energy resolution of 26% was obtained. An integral non linearity better than 0.3% and a position resolution better than 1 mm have been observed. The information corresponding to each one of the coordinates were digitized by a TDC in a CAMAC system and stored event by event in a micro-computer (IBM-AT). (author) 56 refs., 68 figs.

Simulation of oscillatory processes in a beam-plasma system with a virtual cathode in gas-filled interaction space

International Nuclear Information System (INIS)

Filatov, R. A.; Hramov, A. E.

2011-01-01

Physical processes occurring in an intense electron beam with a virtual cathode in an interaction space filled with neutral gas are studied in a two-dimensional model. A mathematical model is proposed for investigating complicated self-consistent processes of neutral gas ionization by the beam electrons and the dynamics of an electron beam and heavy positive ions in the common space charge field with allowance for the two-dimensional motion of charged particles. Three characteristic dynamic regimes of the system are revealed: complete suppression of oscillations of the virtual cathode as a result of neutralizing its space charge by positive ions; the pulsed generation regime, in which the ions dynamics repeatedly suppresses and restores the virtual cathode oscillations; and the continuous generation regime with an anomalously high level of noisy oscillations.

Double discharges in unipolar-pulsed dielectric barrier discharge xenon excimer lamps

International Nuclear Information System (INIS)

Liu Shuhai; Neiger, Manfred

2003-01-01

Excitation of dielectric barrier discharge xenon excimer lamps by unipolar short square pulses is studied in this paper. Two discharges with different polarity are excited by each voltage pulse (double discharge phenomenon). The primary discharge occurs at the top or at the rising flank of the applied unipolar square pulse, which is directly energized by the external circuit. The secondary discharge with the reversed polarity occurs at the falling flank or shortly after the falling flank end (zero external voltage) depending on the pulse width, which is energized by the energy stored by memory charges deposited by the primary discharge. Fast-speed ICCD imaging shows the primary discharge has a conic discharge appearance with a channel broadening on the anode side. This channel broadening increases with increasing the pulse top level. Only the anode-side surface discharge is observed in the primary discharge. The surface discharge on the cathode side which is present in bipolar sine voltage excitation is not observed. On the contrary, the secondary discharge has only the cathode-side surface discharge. The surface discharge on the anode side is not observed. The secondary discharge is much more diffuse than the primary discharge. Time-resolved emission measurement of double discharges show the secondary discharge emits more VUV xenon excimer radiation but less infrared (IR) xenon atomic emission than the primary discharge. It was found that the IR xenon atomic emission from the secondary discharge can be reduced by shortening the pulse width. The energy efficiency of unipolar-pulsed xenon excimer lamps (the overall energy efficiency of double discharges) is much higher than that obtained under bipolar sine wave excitation. The output VUV spectrum under unipolar pulse excitation is found to be identical to that under sine wave excitation and independent of injected electric power

Cathode materials review

Science.gov (United States)

Daniel, Claus; Mohanty, Debasish; Li, Jianlin; Wood, David L.

2014-06-01

The electrochemical potential of cathode materials defines the positive side of the terminal voltage of a battery. Traditionally, cathode materials are the energy-limiting or voltage-limiting electrode. One of the first electrochemical batteries, the voltaic pile invented by Alessandro Volta in 1800 (Phil. Trans. Roy. Soc. 90, 403-431) had a copper-zinc galvanic element with a terminal voltage of 0.76 V. Since then, the research community has increased capacity and voltage for primary (nonrechargeable) batteries and round-trip efficiency for secondary (rechargeable) batteries. Successful secondary batteries have been the lead-acid with a lead oxide cathode and a terminal voltage of 2.1 V and later the NiCd with a nickel(III) oxide-hydroxide cathode and a 1.2 V terminal voltage. The relatively low voltage of those aqueous systems and the low round-trip efficiency due to activation energies in the conversion reactions limited their use. In 1976, Wittingham (J. Electrochem. Soc., 123, 315) and Besenhard (J. Power Sources 1(3), 267) finally enabled highly reversible redox reactions by intercalation of lithium ions instead of by chemical conversion. In 1980, Goodenough and Mizushima (Mater. Res. Bull. 15, 783-789) demonstrated a high-energy and high-power LiCoO2 cathode, allowing for an increase of terminal voltage far beyond 3 V. Over the past four decades, the international research community has further developed cathode materials of many varieties. Current state-of-the-art cathodes demonstrate voltages beyond any known electrolyte stability window, bringing electrolyte research once again to the forefront of battery research.

Cathode materials review

International Nuclear Information System (INIS)

Daniel, Claus; Mohanty, Debasish; Li, Jianlin; Wood, David L.

2014-01-01

The electrochemical potential of cathode materials defines the positive side of the terminal voltage of a battery. Traditionally, cathode materials are the energy-limiting or voltage-limiting electrode. One of the first electrochemical batteries, the voltaic pile invented by Alessandro Volta in 1800 (Phil. Trans. Roy. Soc. 90, 403-431) had a copper-zinc galvanic element with a terminal voltage of 0.76 V. Since then, the research community has increased capacity and voltage for primary (nonrechargeable) batteries and round-trip efficiency for secondary (rechargeable) batteries. Successful secondary batteries have been the lead-acid with a lead oxide cathode and a terminal voltage of 2.1 V and later the NiCd with a nickel(III) oxide-hydroxide cathode and a 1.2 V terminal voltage. The relatively low voltage of those aqueous systems and the low round-trip efficiency due to activation energies in the conversion reactions limited their use. In 1976, Wittingham (J. Electrochem. Soc., 123, 315) and Besenhard (J. Power Sources 1(3), 267) finally enabled highly reversible redox reactions by intercalation of lithium ions instead of by chemical conversion. In 1980, Goodenough and Mizushima (Mater. Res. Bull. 15, 783-789) demonstrated a high-energy and high-power LiCoO 2 cathode, allowing for an increase of terminal voltage far beyond 3 V. Over the past four decades, the international research community has further developed cathode materials of many varieties. Current state-of-the-art cathodes demonstrate voltages beyond any known electrolyte stability window, bringing electrolyte research once again to the forefront of battery research

Cathode materials review

Energy Technology Data Exchange (ETDEWEB)

Daniel, Claus, E-mail: danielc@ornl.gov; Mohanty, Debasish, E-mail: danielc@ornl.gov; Li, Jianlin, E-mail: danielc@ornl.gov; Wood, David L., E-mail: danielc@ornl.gov [Oak Ridge National Laboratory, 1 Bethel Valley Road, MS6472 Oak Ridge, TN 37831-6472 (United States)

2014-06-16

The electrochemical potential of cathode materials defines the positive side of the terminal voltage of a battery. Traditionally, cathode materials are the energy-limiting or voltage-limiting electrode. One of the first electrochemical batteries, the voltaic pile invented by Alessandro Volta in 1800 (Phil. Trans. Roy. Soc. 90, 403-431) had a copper-zinc galvanic element with a terminal voltage of 0.76 V. Since then, the research community has increased capacity and voltage for primary (nonrechargeable) batteries and round-trip efficiency for secondary (rechargeable) batteries. Successful secondary batteries have been the lead-acid with a lead oxide cathode and a terminal voltage of 2.1 V and later the NiCd with a nickel(III) oxide-hydroxide cathode and a 1.2 V terminal voltage. The relatively low voltage of those aqueous systems and the low round-trip efficiency due to activation energies in the conversion reactions limited their use. In 1976, Wittingham (J. Electrochem. Soc., 123, 315) and Besenhard (J. Power Sources 1(3), 267) finally enabled highly reversible redox reactions by intercalation of lithium ions instead of by chemical conversion. In 1980, Goodenough and Mizushima (Mater. Res. Bull. 15, 783-789) demonstrated a high-energy and high-power LiCoO{sub 2} cathode, allowing for an increase of terminal voltage far beyond 3 V. Over the past four decades, the international research community has further developed cathode materials of many varieties. Current state-of-the-art cathodes demonstrate voltages beyond any known electrolyte stability window, bringing electrolyte research once again to the forefront of battery research.

Magnetic discharge accelerating diode for the gas-filled pulsed neutron generators based on inertial confinement of ions

International Nuclear Information System (INIS)

Kozlovskij, K I; Shikanov, A E; Vovchenko, E D; Shatokhin, V L; Isaev, A A; Martynenko, A S

2016-01-01

The paper deals with magnetic discharge diode module with inertial electrostatic ions confinement for the gas-filled pulsed neutron generators. The basis of the design is geometry with the central hollow cathode surrounded by the outer cylindrical anode and electrodes made of permanent magnets. The induction magnitude about 0.1-0.4 T in the central region of the discharge volume ensures the confinement of electrons in the space of hollow (virtual) cathode and leads to space charge compensation of accelerated ions in the centre. The research results of different excitation modes in pulsed high-voltage discharge are presented. The stable form of the volume discharge preserveing the shape and amplitude of the pulse current in the pressure range of 10 -3 -10 -1 Torr and at the accelerating voltage up to 200 kV was observed. (paper)

Anatomy Comic Strips

Science.gov (United States)

Park, Jin Seo; Kim, Dae Hyun; Chung, Min Suk

2011-01-01

Comics are powerful visual messages that convey immediate visceral meaning in ways that conventional texts often cannot. This article's authors created comic strips to teach anatomy more interestingly and effectively. Four-frame comic strips were conceptualized from a set of anatomy-related humorous stories gathered from the authors' collective…

Influence of nonuniform external magnetic fields and anode--cathode shaping on magnetic insulation in coaxial transmission lines

International Nuclear Information System (INIS)

Mostrom, M.A.

1979-01-01

Coaxial transmission lines, used to transfer the high voltage pulse into the diode region of a relativistic electron beam generator, have been studied using the two-dimensional time-dependent fully relativistic and electromagnetic particle simulation code CCUBE. A simple theory of magnetic insulation that agrees well with simulation results for a straight cylindrical coax in a uniform external magnetic field is used to interpret the effects of anode--cathode shaping and nonuniform external magnetic fields. Loss of magnetic insulation appears to be minimized by satisfying two conditions: (1) the cathode surface should follow a flux surface of the external magnetic field; (2) the anode should then be shaped to insure that the magnetic insulation impedance, including transients, is always greater than the effective load impedance wherever there is an electron flow in the anode--cathode gap

The influence of cathode excavation of cathodic arc evaporator on thickness uniformity and erosion products angle distribution

Directory of Open Access Journals (Sweden)

D. V. Duhopel'nikov

2014-01-01

Full Text Available Cathodic arc evaporators are used for coating with functional films. Prolonged or buttend evaporators may be used for this purposes. In butt-end evaporator the cathode spots move continuously on the cathode work surface and evaporate cathode material. High depth excavation profile forms on the cathode work surface while the thick coating precipitation (tens or hundreds of microns. The cathode excavation profile is shaped like a “cup” with high walls for electrostatic discharge stabilization systems with axial magnetic fields. Cathode spots move on the bottom of the “cup”. It is very likely that high “cup” walls are formed as a result of lasting work time influence on the uniformity of precipitated films.In the present work the influence of excavation profile walls height on the uniformity of precipitated coating was carried out. The high profile walls are formed due to lasting work of DC vacuum arc evaporator. The cathode material used for tests was 3003 aluminum alloy. The extended substrate was placed parallel to the cathode work surface. Thickness distribution along the substrate length with the new cathode was obtained after 6 hours and after 12 hours of continuous operation.The thickness distribution of precipitated coating showed that the cathode excavation has an influence on the angular distribution of the matter escaping the cathode. It can be clearly seen from the normalized dependence coating thickness vs the distance from the substrate center. Also the angular distribution of the matter flow from the cathode depending on the cathode working time was obtained. It was shown that matter flow from the cathode differs from the LambertKnudsen law. The more the cathode excavation the more this difference.So, cathode excavation profile has an influence on the uniformity of precipitated coating and it is necessary to take in account the cathode excavation profile while coating the thick films.

Response of multi-strip multi-gap resistive plate chamber using pulsed electron beam

International Nuclear Information System (INIS)

Datta Pramanik, U.; Chakraborty, S.; Rahaman, A.; Ray, J.; Chatterjee, S.; Bemmerer, D.; Elekes, Z.; Kempe, M.; Sobiella, M.; Stach, D.; Wagner, A.; Yakorev, D.; Leifels, Y.; Simon, H.

2011-01-01

A prototype of Multi-strip Multi-gap Resistive Plate Chamber (MMRPC) with active area 40 cm x 20 cm has been developed at SINP, Kolkata. Electron response of the developed detector was studied using the electron linac ELBE at Forschungszentrum Dresden-Rossendorf. The development of this detector started with the aim of developing a neutron detector but this ultrafast timing detector can be used efficiently for the purpose of medical imaging, security purpose and detection of minimum ionising particle. In this article detailed analysis of electron response to our developed MMRPC will be presented

Nanostructured sulfur cathodes

KAUST Repository

Yang, Yuan

2013-01-01

Rechargeable Li/S batteries have attracted significant attention lately due to their high specific energy and low cost. They are promising candidates for applications, including portable electronics, electric vehicles and grid-level energy storage. However, poor cycle life and low power capability are major technical obstacles. Various nanostructured sulfur cathodes have been developed to address these issues, as they provide greater resistance to pulverization, faster reaction kinetics and better trapping of soluble polysulfides. In this review, recent developments on nanostructured sulfur cathodes and mechanisms behind their operation are presented and discussed. Moreover, progress on novel characterization of sulfur cathodes is also summarized, as it has deepened the understanding of sulfur cathodes and will guide further rational design of sulfur electrodes. © 2013 The Royal Society of Chemistry.

Particle-in-cell simulation of Trichel pulses in pure oxygen

International Nuclear Information System (INIS)

Soria-Hoyo, C; Pontiga, F; Castellanos, A

2007-01-01

The development and propagation of Trichel pulses in oxygen have been numerically simulated using an improved fluid particle-in-cell (PIC) method. The numerical method has been optimized to accurately reproduce sequences of about 100 Trichel pulses (∼1 ms). A classical one-dimensional model of negative corona in sphere-to-plane geometry has been used to formulate the continuity equations for electrons and ions. The effects of ionization, attachment and secondary-electron emission from the cathode have all been considered. The electric field has been obtained from the solution of Poisson's equation in two dimensions. Using this model, the temporal and electrical characteristics of Trichel pulses have been investigated, in particular, the relation between applied voltage, pulse frequency and time-averaged current intensity and charge

Expansion of the cathode spot and generation of shock waves in the plasma of a volume discharge in atmospheric-pressure helium

International Nuclear Information System (INIS)

Omarov, O. A.; Kurbanismailov, V. S.; Arslanbekov, M. A.; Gadzhiev, M. Kh.; Ragimkhanov, G. B.; Al-Shatravi, Ali J. G.

2012-01-01

The expansion of the cathode spot and the generation of shock waves during the formation and development of a pulsed volume discharge in atmospheric-pressure helium were studied by analyzing the emission spectra of the cathode plasma and the spatiotemporal behavior of the plasma glow. The transition of a diffuse volume discharge in a centimeter-long gap into a high-current diffuse mode when the gas pressure increased from 1 to 5 atm and the applied voltage rose from the statistical breakdown voltage to a 100% overvoltage was investigated. Analytical expressions for the radius of the cathode spot and its expansion velocity obtained in the framework of a spherically symmetric model agree satisfactorily with the experimental data.

Pulsed Current-Voltage-Induced Perturbations of a Premixed Propane/Air Flame

Directory of Open Access Journals (Sweden)

Jacob. B. Schmidt

2011-01-01

Full Text Available The effect of millisecond wide sub-breakdown pulsed voltage-current induced flow perturbation has been measured in premixed laminar atmospheric pressure propane/air flame. The flame equivalence ratios were varied from 0.8 to 1.2 with the flow speeds near 1.1 meter/second. Spatio-temporal flame structure changes were observed through collection of CH (A-X and OH (A-X chemiluminescence and simultaneous spontaneous Raman scattering from N2. This optical collection scheme allows us to obtain a strong correlation between the measured gas temperature and the chemiluminescence intensity, verifying that chemiluminescence images provide accurate measurements of flame reaction zone structure modifications. The experimental results suggest that the flame perturbation is caused by ionic wind originating only from the radial positive space-charge distribution in/near the cathode fall. A net momentum transfer acts along the annular space discharge distribution in the reaction zone at or near the cathode fall which modifies the flow field near the cathodic burner head. This radially inward directed body force appears to enhance mixing similar to a swirl induced modification of the flame structure. The flame fluidic response exhibit a strong dependence on the voltage pulse width ≤10 millisecond.

Luminous flux improvement of xenon fluorescent lamps by applying synchronized high-voltage pulse to the auxiliary external electrode

Energy Technology Data Exchange (ETDEWEB)

Motomura, Hideki; Oka, Kojiro; Sogabe, Toru; Jinno, Masafumi, E-mail: hmoto@mayu.ee.ehime-u.ac.jp [Department of Electrical and Electronic Engineering, Ehime University 3 Bunkyo-cho, Matsuyama, Ehime 790-8577 (Japan)

2011-06-08

As the environmental awareness of people becomes stronger, the demand for mercury-free light sources also becomes stronger. The authors have been developing cold cathode fluorescent lamps in which xenon gas is filled as an ultraviolet radiator instead of mercury. Previously the authors reported the luminous flux enhancement method using a grounded auxiliary external electrode (AEE). In this paper, in order to improve the luminous flux much more, a positive voltage pulse which was synchronized to the main driving negative voltage pulse was applied to the AEE. As a result, the maximum input power increased under which the positive column did not constrict and the luminous flux improved by 70% at the xenon filling pressure of 6.7 kPa. It is proved that the positive voltage pulse application to the AEE with the amplitude of more than 2 kV expands the positive column in the radial direction. It is attributed to the phenomenon that the residual ions and electrons, which are generated by dielectric barrier discharge between the AEE and the anode during the falling edge of the negative pulse to the cathode, spread the discharge path from the anode towards the AEE during the cold cathode discharge mode. By increasing the xenon filling pressure, luminous efficacy was improved to 25 lm W{sup -1}.

Arcjet cathode phenomena

Science.gov (United States)

Curran, Francis M.; Haag, Thomas W.; Raquet, John F.

1989-01-01

Cathode tips made from a number of different materials were tested in a modular arcjet thruster in order to examine cathode phenomena. Periodic disassembly and examination, along with the data collected during testing, indicated that all of the tungsten-based materials behaved similarly despite the fact that in one of these samples the percentage of thorium oxide was doubled and another was 25 percent rhenium. The mass loss rate from a 2 percent thoriated rhenium cathode was found to be an order of magnitude greater than that observed using 2 percent thoriated tungsten. Detailed analysis of one of these cathode tips showed that the molten crater contained pure tungsten to a depth of about 150 microns. Problems with thermal stress cracking were encountered in the testing of a hafnium carbide tip. Post test analysis showed that the active area of the tip had chemically reacted with the propellant. A 100 hour continuous test was run at about 1 kW. Post test analysis revealed no dendrite formation, such as observed in a 30 kW arcjet lifetest, near the cathode crater. The cathodes from both this test and a previously run 1000 hour cycled test displayed nearly identical arc craters. Data and calculations indicate that the mass losses observed in testing can be explained by evaporation.

Study of the physical processes involved in the operating mode of the micro-strips gas detector Micromegas

International Nuclear Information System (INIS)

Barouch, G.

2001-04-01

Micromegas is a micro-strip gaseous detector invented in 1996. It consists of two volumes of gas separated by a micro-mesh. The first volume of gas, 3 mm thick, is used to liberate ionization electrons from the incident charged particle. In the second volume, only 100 μm thick, an avalanche phenomenon amplifies the electrons produced in the first volume. Strips printed on an insulating substrate collect the electrons from the avalanche. The geometrical configuration of Micromegas showed many advantages. The short anode-cathode distance combined with a high granularity provide high rate capabilities due to a fast collection of ions produced during the avalanche development. Moreover, the possibility to localize the avalanche with strips printed about every hundreds of micrometers allows to measure the position of the incident particle with a good resolution. In this work, experimental tests of Micromegas are presented along with detailed Monte Carlo simulations used to understand and optimize the detector's performances. The prototypes were tested several times at the PS accelerator at CERN. The analysis of the date showed a stable and efficient behavior of Micromegas combined with an excellent space resolution. In fact, spatial resolutions of less than 15 μm were obtained. In parallel with the in-beam tests, several simulations have been developed in order to gain a better understanding of the detector's response. (author)

Science Comic Strips

Science.gov (United States)

Kim, Dae Hyun; Jang, Hae Gwon; Shin, Dong Sun; Kim, Sun-Ja; Yoo, Chang Young; Chung, Min Suk

2012-01-01

Science comic strips entitled Dr. Scifun were planned to promote science jobs and studies among professionals (scientists, graduate and undergraduate students) and children. To this end, the authors collected intriguing science stories as the basis of scenarios, and drew four-cut comic strips, first on paper and subsequently as computer files.…

A novel pulsed corona discharge reactor based on surface streamers for diesel exhaust remediation

Energy Technology Data Exchange (ETDEWEB)

Malik, M.A.; Schoenbach, K.H. [Old Dominion Univ., Norfolk, VA (United States). Frank Reidy Research Center for Bioelectrics

2010-07-01

Modelling of surface streamers along insulating surfaces to determine the dielectric strength of insulators in high voltage systems has shown that surface streamers consist of a positive streamer head followed by quasi-neutral plasma in the channel behind and surrounded by a layer of positive charges. This paper described a novel pulsed corona discharge reactor which utilized such surface streamers along insulating surfaces. The electrodes were comprised of a stainless steel wire anode of 150 mm in diameter stretched along the surface of a glass sheet and two parallel aluminum strips as cathodes. An eight-stage Marx bank, was used to produce the surface streamers in nitrogen-oxygen mixtures at atmospheric pressure. The paper described the experimental study with particular reference to the schematics of a surface streamer plasma reactor and the dimensions of discharge spaces of three reactors. The purpose of the study was to find the optimum conditions for energy yield and effective destruction of nitrogen oxides from diesel engine exhaust. It was concluded that surface streamers generate a more diffuse plasma. Energy costs for production of ozone or nitrogen dioxide that require reactions with bulk gas molecules were nearly the same in surface streamer discharges as in volume streamer discharges. 12 refs., 1 tab., 7 figs.

Electro-thermal modelling of anode and cathode in micro-EDM

International Nuclear Information System (INIS)

Yeo, S H; Kurnia, W; Tan, P C

2007-01-01

Micro-electrical discharge machining is an evolution of conventional EDM used for fabricating three-dimensional complex micro-components and microstructure with high precision capabilities. However, due to the stochastic nature of the process, it has not been fully understood. This paper proposes an analytical model based on electro-thermal theory to estimate the geometrical dimensions of micro-crater. The model incorporates voltage, current and pulse-on-time during material removal to predict the temperature distribution on the workpiece as a result of single discharges in micro-EDM. It is assumed that the entire superheated area is ejected from the workpiece surface while only a small fraction of the molten area is expelled. For verification purposes, single discharge experiments using RC pulse generator are performed with pure tungsten as the electrode and AISI 4140 alloy steel as the workpiece. For the pulse-on-time range up to 1000 ns, the experimental and theoretical results are found to be in close agreement with average volume approximation errors of 2.7% and 6.6% for the anode and cathode, respectively

Electro-thermal modelling of anode and cathode in micro-EDM

Energy Technology Data Exchange (ETDEWEB)

Yeo, S H; Kurnia, W; Tan, P C [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)

2007-04-21

Micro-electrical discharge machining is an evolution of conventional EDM used for fabricating three-dimensional complex micro-components and microstructure with high precision capabilities. However, due to the stochastic nature of the process, it has not been fully understood. This paper proposes an analytical model based on electro-thermal theory to estimate the geometrical dimensions of micro-crater. The model incorporates voltage, current and pulse-on-time during material removal to predict the temperature distribution on the workpiece as a result of single discharges in micro-EDM. It is assumed that the entire superheated area is ejected from the workpiece surface while only a small fraction of the molten area is expelled. For verification purposes, single discharge experiments using RC pulse generator are performed with pure tungsten as the electrode and AISI 4140 alloy steel as the workpiece. For the pulse-on-time range up to 1000 ns, the experimental and theoretical results are found to be in close agreement with average volume approximation errors of 2.7% and 6.6% for the anode and cathode, respectively.

Electro-thermal modelling of anode and cathode in micro-EDM

Science.gov (United States)

Yeo, S. H.; Kurnia, W.; Tan, P. C.

2007-04-01

Micro-electrical discharge machining is an evolution of conventional EDM used for fabricating three-dimensional complex micro-components and microstructure with high precision capabilities. However, due to the stochastic nature of the process, it has not been fully understood. This paper proposes an analytical model based on electro-thermal theory to estimate the geometrical dimensions of micro-crater. The model incorporates voltage, current and pulse-on-time during material removal to predict the temperature distribution on the workpiece as a result of single discharges in micro-EDM. It is assumed that the entire superheated area is ejected from the workpiece surface while only a small fraction of the molten area is expelled. For verification purposes, single discharge experiments using RC pulse generator are performed with pure tungsten as the electrode and AISI 4140 alloy steel as the workpiece. For the pulse-on-time range up to 1000 ns, the experimental and theoretical results are found to be in close agreement with average volume approximation errors of 2.7% and 6.6% for the anode and cathode, respectively.

A CMOS 130nm Evaluation digitzer chip for silicon strips readout

CERN Document Server

Da Silva, W; Dhellot, M; Fougeron, D; Genat, J F; Hermel, R; Huppert, J f; Kapusta, F; Lebbolo, H; Pham, T H; Rossel, F; Savoy-navarro, A; Sefri, R; Vilalte

2007-01-01

A CMOS 130nm evaluation chip intended to read Silicon strip detectors at the ILC has been designed and successfully tested. Optimized for a detector capacitance of 10 pF, it includes four channels of charge integration, pulse shaping, a 16-deep analogue sampler triggered on input analogue sums, and parallel analogue to digital conversion. Tests results of the full chain are reported, demonstrating the behaviour and performance of the full sampling process and analogue to digital conversion. Each channel dissipates less than one milli-Watt static power.

Part I. Application of pulse polarography and pulse anodic stripping to the determination of selected heavy metals in natural waters. Part II. Application of controlled potential coulometric techniques to the determination of uranium

International Nuclear Information System (INIS)

Crosmun, S.T.

1977-06-01

The use of a thin mercury film wax-impregnated graphite electrode for the simultaneous determination of cadmium, lead and zinc in an acetate buffer by differential pulse anodic stripping voltammetry is described. Optimal instrumental parameters for maximum resolution and sensitivity for simultaneous analysis of these three elements in natural waters are discussed. The interference of copper with the determination of zinc is investigated in detail. An optimal mercury film thickness for this electrode is suggested. A method utilizing differential pulse polarography for the determination of chromium (VI) in natural water is described. Additions of 0.62 μg Cu(II) ml -1 and 0.55 μg Fe(III) ml -1 did not interfere with the determination of 0.050 μg Cr(VI) ml -1 . The natural water samples containing Cr(VI) were buffered to approximately pH 7 with 0.1 M ammonium acetate and 0.005 M ethylenediamine and analyzed. Natural water samples of chromium from 0.035 μg to 2.0 μg.ml -1 may be analyzed directly without further preparation. The detection limit is 0.010 μg.ml -1 . A novel, highly efficient cell with integral stirrer for controlled potential coulometry is described. This cell was used to demonstrate the feasibility of determining uranium (VI) by predictive coulometry. A PDP 8/I minicomputer was used to predict the coulometric endpoint with high accuracy within 2.5 minutes in a titration which normally takes about 10 minutes. This technique was shown to yield acceptable results even in the presence of an interfering phosphate matrix

Two-dimensional spatial survey of the plasma potential and electric field in a pulsed bipolar magnetron discharge

International Nuclear Information System (INIS)

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

2004-01-01

Emissive and Langmuir probe techniques have been used to obtain two-dimensional (2D) spatial maps of the plasma potential V p , electric field E, and ion trajectories in a pulsed bipolar magnetron discharge. The magnetron was pulsed at a frequency of 100 kHz, with a 50% duty cycle and operated at an argon pressure of 0.74 Pa. The pulse wave form was characterized by three distinct phases: the 'overshoot', 'reverse', and 'on' phases. In the 'on' phase of the pulse, when the cathode voltage is driven to -670 V, the 2D spatial distribution of V p has a similar form to that in dc magnetron, with significant axial and radial electric fields in the bulk plasma, accelerating ions to the sheath edge above the cathode racetrack region. During the 'overshoot' phase (duration 200 ns), V p is raised to values greater than +330 V, more than 100 V above the cathode potential, with E pointing away from the target. In the 'reverse' phase V p has a value of +45 V at all measured positions, 2 V more positive than the target potential. In this phase there is no electric field present in the plasma. In the bulk of the plasma, the results from Langmuir probe and the emissive probe are in good agreement, however, in one particular region of the plasma outside the radius of the cathode, the emissive probe measurements are consistently more positive (up to 45 V in the 'on' time). This discrepancy is discussed in terms of the different frequency response of the probes and their perturbation of the plasma. A simple circuit model of the plasma-probe system has been proposed to explain our results. A brief discussion of the effect of the changing plasma potential distribution on the operation of the magnetron is given

A sub-picosecond pulsed 5 MeV electron beam system

International Nuclear Information System (INIS)

Farrell, J. Paul; Batchelor, K.; Meshkovsky, I.; Pavlishin, I.; Lekomtsev, V.; Dyublov, A.; Inochkin, M.; Srinivasan-Rao, T.

2001-01-01

Laser excited pulsed, electron beam systems that operate at energies from 1 MeV up to 5 MeV and pulse width from 0.1 to 100 ps are described. The systems consist of a high voltage pulser and a coaxial laser triggered gas or liquid spark gap. The spark gap discharges into a pulse forming line designed to produce and maintain a flat voltage pulse for 1 ns duration on the cathode of a photodiode. A synchronized laser is used to illuminate the photocathode with a laser pulse to produce an electron beam with very high brightness, short duration, and current at or near the space charge limit. Operation of the system is described and preliminary test measurements of voltages, synchronization, and jitter are presented for a 5 MeV system. Applications in chemistry, and accelerator research are briefly discussed

The Strip Module

DEFF Research Database (Denmark)

Pedersen, Tommy

1996-01-01

When the behaviour of a ship in waves is to be predicted it is convenient to have a tool which includes different approaches to the problem.The aim of this project is to develop such a tool named the strip theory module. The strip theory module will consist of submodules dependent on the I...

Signal propagation in straw tubes with resistive cathodes

International Nuclear Information System (INIS)

Marzec, J.; Zaremba, K.; Pawlowski, Z.; Konarzewski, B.

2000-01-01

The analysis presented in this paper is part of the research performed by the authors for the COMPASS experiment at CERN. They have developed a theoretical model of the signal transmission in a straw tube. In contrast to commonly used simplified models, their approach takes into account the energy losses in the cathode resistance. This model allows determination of the main electrical parameters, such as characteristic impedance and signal attenuation, as well as a detailed simulation of the pulse shape dependent on the point of the charge injection. Simulation results have been compared with the results of experimental measurements of different types of the straw detectors

Signal propagation in straw tubes with resistive cathodes

Energy Technology Data Exchange (ETDEWEB)

Marzec, J.; Zaremba, K.; Pawlowski, Z.; Konarzewski, B.

2000-02-01

The analysis presented in this paper is part of the research performed by the authors for the COMPASS experiment at CERN. They have developed a theoretical model of the signal transmission in a straw tube. In contrast to commonly used simplified models, their approach takes into account the energy losses in the cathode resistance. This model allows determination of the main electrical parameters, such as characteristic impedance and signal attenuation, as well as a detailed simulation of the pulse shape dependent on the point of the charge injection. Simulation results have been compared with the results of experimental measurements of different types of the straw detectors.

Signal propagation in straw tubes with resistive cathode

CERN Document Server

Marzec, J; Pawlowski, Z; Konarzewski, B

2000-01-01

The analysis presented in this paper is part of the research performed by the authors for the COMPASS experiment at CERN. We have developed a theoretical model of the signal transmission in a straw tube. In contrast to commonly used simplified models, our approach takes into account the energy losses in the cathode resistance. This model allows determination of the main electrical parameters, such as characteristic impedance and signal attenuation, as well as a detailed simulation of the pulse shape dependent on the point of the charge injection. Simulation results have been compared with the results of experimental measurements of different types of the straw detectors. (7 refs).

Nuclear reactor spring strip grid spacer

International Nuclear Information System (INIS)

Patterson, J.F.; Flora, B.S.

1978-01-01

A bimetallic grid spacer is described comprising a grid structure of zircaloy formed by intersecting striplike members which define fuel element openings for receiving fuel elements and spring strips made of Inconel positioned within the grid structure for cooperating with the fuel elements to maintain them in their desired position. A plurality of these spring strips extend longitudinally between sides of the grid structure, being locked in position by the grid retaining strips. The fuel rods, which are disposed in the fuel openings formed in the grid structure, are positioned by means of the springs associated with the spring strips and a plurality of dimples which extend from the zircaloy grid structure into the openings. In one embodiment the strips are disposed in a plurality of arrays with those spring strip arrays situated in opposing diagonal quadrants of the grid structure extending in the same direction and adjacent spring strip arrays in each half of the spacer extending in relatively perpendicular directions. Other variations of the spring strip arrangements for a particular fuel design are disclosed herein

Adsorptive stripping differential pulse voltammetric determination of venlafaxine and desvenlafaxine employing Nafion-carbon nanotube composite glassy carbon electrode

Energy Technology Data Exchange (ETDEWEB)

Sanghavi, Bankim J. [Department of Chemistry, University of Mumbai, Vidyanagari, Santacruz (East), Mumbai 400 098, Maharashtra (India); Srivastava, Ashwini K., E-mail: aksrivastava@chem.mu.ac.i [Department of Chemistry, University of Mumbai, Vidyanagari, Santacruz (East), Mumbai 400 098, Maharashtra (India)

2011-04-15

A Nafion-carbon nanotube-modified glassy carbon electrode (NAF-CNT-GCE) was developed for the determination of venlafaxine (VF) and desvenlafaxine (DVF). The electrochemical behavior of both these molecules was investigated employing cyclic voltammetry (CV), chronocoulometry (CC), electrochemical impedance spectroscopy (EIS) and adsorptive stripping differential pulse voltammetry (AdSDPV). The surface morphology of the electrodes has been studied by means of scanning electron microscopy (SEM). These studies revealed that the oxidation of VF and DVF is facilitated at NAF-CNT-GCE. After optimization of analytical conditions employing this electrode at pH 7.0 in Britton-Robinson buffer (0.05 M) for VF and pH 5.0 in acetate buffer (0.1 M) for DVF, the peak currents for both the molecules were found to vary linearly with their concentrations in the range of 3.81 x 10{sup -8}-6.22 x 10{sup -5} M for VF and 5.33 x 10{sup -8}-3.58 x 10{sup -5} M for DVF. The detection limits (S/N = 3) of 1.24 x 10{sup -8} and 2.11 x 10{sup -8} M were obtained for VF and DVF, respectively, using AdSDPV. The prepared modified electrode showed several advantages, such as simple preparation method, high sensitivity, very low detection limits and excellent reproducibility. The proposed method was employed for the determination of VF and DVF in pharmaceutical formulations, urine and blood serum samples.

Characterization of galvannealed strip

International Nuclear Information System (INIS)

Moreas, G.; Hardy, Y.

1999-01-01

With the aim of enhancing coating quality control during galvannealing process, an online microscopic image acquisition sensor has been developed at CRM. In galvannealing process, the ζ phase surface density is a coating quality characteristic, and the on-line microscope, equipped with optics placed at 20 mm from the surface, grabs 250 μm x 190 μm images on which ζ crystals (approximate dimensions: 1 μm x 10 μm) can be clearly identified. On-line, the sensor is mounted in front of a roll where the strip has a stable position. The coating surface to sensor optics distance is continuously measured by an accurate triangulation sensor (1 μm repeatability) and is adjusted in such a way that, due to roll eccentricity, the image is focused at least twice per revolution. When focused, image of moving product is frozen by a short (10 ns) laser light pulse and is grabbed. The obtained image is then processed to extract ζ phase percentage and allows adjustment of process parameters to reach the desired coating characteristics. (author)

Noise analysis due to strip resistance in the ATLAS SCT silicon strip module

International Nuclear Information System (INIS)

Kipnis, I.

1996-08-01

The module is made out of four 6 cm x 6 cm single sided Si microstrip detectors. Two detectors are butt glued to form a 12 cm long mechanical unit and strips of the two detectors are electrically connected to form 12 cm long strips. The butt gluing is followed by a back to back attachment. The module in this note is the Rφ module where the electronics is oriented parallel to the strip direction and bonded directly to the strips. This module concept provides the maximum signal-to-noise ratio, particularly when the front-end electronics is placed near the middle rather than at the end. From the noise analysis, it is concluded that the worst-case ΔENC (far-end injection) between end- and center-tapped modules will be 120 to 210 el. rms (9 to 15%) for a non-irradiated detector and 75 to 130 el. rms (5 to 9%) for an irradiated detector, for a metal strip resistance of 10 to 20 Ω/cm

Anodic stripping voltammetric determination of heavy metals in solutions containing humic acids

International Nuclear Information System (INIS)

Labuda, J.; Saur, D.; Neeb, R.

1994-01-01

Various simultaneous effects of humic acids on the current and potential of differential pulse anodic stripping peaks of copper, lead, cadmium and zinc in weakly alkaline and acidic (pH 2) solutions have been investigated and interpreted with regard to metal complexation and the adsorption of humic acid on the mercury electrode. The applicability of the standard additions method for metal quantitation and the experimental conditions for UV-photolysis with a high-pressure mercury lamp have been examined in model as well as real water samples. (orig.)

Evaluation of circulating cathodic antigen (CCA) strip for diagnosis of urinary schistosomiasis in Hassoba school children, Afar, Ethiopia

OpenAIRE

Ayele B.; Erko B.; Legesse M.; Hailu A.; Medhin G.

2008-01-01

A total of 206 urine samples collected from Hassoba Elementary schoolchildren, Afar, Ethiopia, a low Schistosoma haematobium endemic setting, was diagnosed to evaluate the performance of CCA strip using double references, urine filtration technique and urinalysis dipstick (Combur 10 Test®) that detect schistosome eggs and blood in urine, respectively. The former was used as a gold standard reference method. Sensitivity, specificity, positive and negative predictive values for the CCA were 52%...

A silicon strip detector dose magnifying glass for IMRT dosimetry

International Nuclear Information System (INIS)

Wong, J. H. D.; Carolan, M.; Lerch, M. L. F.; Petasecca, M.; Khanna, S.; Perevertaylo, V. L.; Metcalfe, P.; Rosenfeld, A. B.

2010-01-01

Purpose: Intensity modulated radiation therapy (IMRT) allows the delivery of escalated radiation dose to tumor while sparing adjacent critical organs. In doing so, IMRT plans tend to incorporate steep dose gradients at interfaces between the target and the organs at risk. Current quality assurance (QA) verification tools such as 2D diode arrays, are limited by their spatial resolution and conventional films are nonreal time. In this article, the authors describe a novel silicon strip detector (CMRP DMG) of high spatial resolution (200 μm) suitable for measuring the high dose gradients in an IMRT delivery. Methods: A full characterization of the detector was performed, including dose per pulse effect, percent depth dose comparison with Farmer ion chamber measurements, stem effect, dose linearity, uniformity, energy response, angular response, and penumbra measurements. They also present the application of the CMRP DMG in the dosimetric verification of a clinical IMRT plan. Results: The detector response changed by 23% for a 390-fold change in the dose per pulse. A correction function is derived to correct for this effect. The strip detector depth dose curve agrees with the Farmer ion chamber within 0.8%. The stem effect was negligible (0.2%). The dose linearity was excellent for the dose range of 3-300 cGy. A uniformity correction method is described to correct for variations in the individual detector pixel responses. The detector showed an over-response relative to tissue dose at lower photon energies with the maximum dose response at 75 kVp nominal photon energy. Penumbra studies using a Varian Clinac 21EX at 1.5 and 10.0 cm depths were measured to be 2.77 and 3.94 mm for the secondary collimators, 3.52 and 5.60 mm for the multileaf collimator rounded leaf ends, respectively. Point doses measured with the strip detector were compared to doses measured with EBT film and doses predicted by the Philips Pinnacle treatment planning system. The differences were 1.1%�

Area specific stripping factors for AGS. A method for extracting stripping factors from survey data

Energy Technology Data Exchange (ETDEWEB)

Aage, H.K.; Korsbech, U. [Technical Univ. of Denmark (Denmark)

2006-04-15

In order to use Airborne Gamma-ray Spectrometry (AGS) for contamination mapping, for source search etc. one must to be able to eliminate the contribution to the spectra from natural radioactivity. This in general is done by a stripping technique. The parameters for performing a stripping have until recently been measured by recording gamma spectra at special calibration sites (pads). This may be cumbersome and the parameters may not be correct when used at low gamma energies for environmental spectra. During 2000-2001 DTU tested with success a new technique for Carborne Gamma-ray Spectrometry (CGS) where the spectra from the surveyed area (or from a similar area) were used for calculating the stripping parameters. It was possible to calculate usable stripping ratios for a number of low energy windows - and weak source signals not detectable by other means were discovered with the ASS technique. In this report it is shown that the ASS technique also works for AGS data, and it has been used for recent Danish AGS tests with point sources. (Check of calibration of AGS parameters.) By using the ASS technique with the Boden data (Barents Rescue) an exercise source was detected that has not been detected by any of the teams during the exercise. The ASS technique therefore seems to be better for search for radiation anomalies than any other method known presently. The experiences also tell that although the stripping can be performed correctly at any altitude there is a variation of the stripping parameters with altitude that has not yet been quite understood. However, even with the oddly variations the stripping worked as expected. It was also observed that one might calculate a single common set of usable stripping factors for all altitudes from the entire data set i.e. some average a, b and c values. When those stripping factors were used the stripping technique still worked well. (au)

Ignitor electrode system design for the pulses electron irradiators device

International Nuclear Information System (INIS)

Lely Susita RM; Ihwanul Aziz

2016-01-01

The designed ignitor electrode system is a system used to initiate the plasma discharge. It consists of two pieces which are placed on both side of the plasma vessel. Each of the ignitor electrode system consists of a cathode, an anode and insulator between the cathode and the anode. The best cathode material for ignitor electrode system is Mg due to its lowest ion erosion rate (γi =11.7 μg/C) and its low cohesive energy (1.51 eV). The specifications of ignitor electrode system designed for the pulse electron irradiators is as follow: Mg cathode materials in the form of rod having a diameter of 6.35 mm and length of 76.75 mm. Anode material are made of non magnetic of SS 304 cylinder shaped with an outer diameter of 88.53 mm, an inner diameter of 81.53 mm and a thickness of 3.50 mm. Insulating material between the cathode and the anode is made of teflon cylinder shaped, outer diameter of 9.50 mm, an inner diameter of 6.35 mm and a length of 30 mm. Based on the ignitor electrode system design, the next step is construction and function test of the ignitor electrode system. (author)

Cathodic Vacuum Arc Plasma of Thallium

International Nuclear Information System (INIS)

Yushkov, Georgy Yu.; Anders, Andre

2006-01-01

Thallium arc plasma was investigated in a vacuum arc ion source. As expected from previous consideration of cathode materials in the Periodic Table of the Elements, thallium plasma shows lead-like behavior. Its mean ion charge state exceeds 2.0 immediately after arc triggering, reaches the predicted 1.60 and 1.45 after about 100 microsec and 150 microsec, respectively. The most likely ion velocity is initially8000 m/s and decays to 6500 m/s and 6200 m/s after 100 microsec and 150microsec, respectively. Both ion charge states and ion velocities decay further towards steady state values, which are not reached within the 300microsec pulses used here. It is argued that the exceptionally high vapor pressure and charge exchange reactions are associated with the establishment of steady state ion values

Particle-in-cell simulation of Trichel pulses in pure oxygen

Energy Technology Data Exchange (ETDEWEB)

Soria-Hoyo, C [Dpto. Electronica y Electromagnetismo, Universidad de Sevilla, Avda. Reina Mercedes s/n, Sevilla 41012 (Spain); Pontiga, F [Dpto. Fisica Aplicada II, Universidad de Sevilla, Avda. Reina Mercedes s/n, Sevilla 41012 (Spain); Castellanos, A [Dpto. Electronica y Electromagnetismo, Universidad de Sevilla, Avda. Reina Mercedes s/n, Sevilla 41012 (Spain)

2007-08-07

The development and propagation of Trichel pulses in oxygen have been numerically simulated using an improved fluid particle-in-cell (PIC) method. The numerical method has been optimized to accurately reproduce sequences of about 100 Trichel pulses ({approx}1 ms). A classical one-dimensional model of negative corona in sphere-to-plane geometry has been used to formulate the continuity equations for electrons and ions. The effects of ionization, attachment and secondary-electron emission from the cathode have all been considered. The electric field has been obtained from the solution of Poisson's equation in two dimensions. Using this model, the temporal and electrical characteristics of Trichel pulses have been investigated, in particular, the relation between applied voltage, pulse frequency and time-averaged current intensity and charge.

Strip casting apparatus and method

Science.gov (United States)

Williams, R.S.; Baker, D.F.

1988-09-20

Strip casting apparatus including a molten-metal-holding container and a nozzle to deposit molten metal onto a moving chill drum to directly cast continuous metallic strip. The nozzle body includes a slot bounded between a back and a front lip. The slot width exceeds about 20 times the gap distance between the nozzle and the chill drum surface. Preferably, the slot width exceeds 0.5 inch. This method of strip casting minimizes pressure drop, insuring better metal-to-chill-drum contact which promotes heat transfer and results in a better quality metallic strip. 6 figs.

PIC simulations of post-pulse field reversal and secondary ionization in nanosecond argon discharges

Science.gov (United States)

Kim, H. Y.; Gołkowski, M.; Gołkowski, C.; Stoltz, P.; Cohen, M. B.; Walker, M.

2018-05-01

Post-pulse electric field reversal and secondary ionization are investigated with a full kinetic treatment in argon discharges between planar electrodes on nanosecond time scales. The secondary ionization, which occurs at the falling edge of the voltage pulse, is induced by charge separation in the bulk plasma region. This process is driven by a reverse in the electric field from the cathode sheath to the formerly driven anode. Under the influence of the reverse electric field, electrons in the bulk plasma and sheath regions are accelerated toward the cathode. The electron movement manifests itself as a strong electron current generating high electron energies with significant electron dissipated power. Accelerated electrons collide with Ar molecules and an increased ionization rate is achieved even though the driving voltage is no longer applied. With this secondary ionization, in a single pulse (SP), the maximum electron density achieved is 1.5 times higher and takes a shorter time to reach using 1 kV 2 ns pulse as compared to a 1 kV direct current voltage at 1 Torr. A bipolar dual pulse excitation can increase maximum density another 50%–70% above a SP excitation and in half the time of RF sinusoidal excitation of the same period. The first field reversal is most prominent but subsequent field reversals also occur and correspond to electron temperature increases. Targeted pulse designs can be used to condition plasma density as required for fast discharge applications.

Optimization of IGCT for pulsed power

International Nuclear Information System (INIS)

Chen Fanglin; Tang Longgu; Chen Yongmin; Pan Xuejun

2014-01-01

In order to develop high-performance IGCT devices applied in pulse power, cathode finger layout is optimized, the finger structure is modified, minority carrier lifetime is properly controlled and gate triggering characteristics is improved. As a result of these measures, the IGCT turn -on di/dt is improved, current handling capability is enhanced and switching response speed is increased. The feasibility and validity of the optimization study on the IGCT is verified by simulation and experimental results. (authors)

Experimental investigation of a 1 kA/cm² sheet beam plasma cathode electron gun.

Science.gov (United States)

Kumar, Niraj; Pal, Udit Narayan; Pal, Dharmendra Kumar; Prajesh, Rahul; Prakash, Ram

2015-01-01

In this paper, a cold cathode based sheet-beam plasma cathode electron gun is reported with achieved sheet-beam current density ∼1 kA/cm(2) from pseudospark based argon plasma for pulse length of ∼200 ns in a single shot experiment. For the qualitative assessment of the sheet-beam, an arrangement of three isolated metallic-sheets is proposed. The actual shape and size of the sheet-electron-beam are obtained through a non-conventional method by proposing a dielectric charging technique and scanning electron microscope based imaging. As distinct from the earlier developed sheet beam sources, the generated sheet-beam has been propagated more than 190 mm distance in a drift space region maintaining sheet structure without assistance of any external magnetic field.

Edge-TCT for the investigation of radiation damaged silicon strip sensors

Energy Technology Data Exchange (ETDEWEB)

Feindt, Finn

2017-02-15

The edge Transient Current Technique (TCT) is a method for the investigation of silicon sensors. This method requires infrared light from a sub-ns pulsed laser to be focused to a μm-size spot and scanned across the polished cut edge of a sensor. Electron-hole pairs are generated along the light beam in the sensor. These charge carriers drift in the electric field and induce transient currents on the sensor electrodes. The current transients are analyzed as a function of the applied voltage, temperature, absorbed dose and position of the laser-light focus, in order to determine the the drift velocities, electric field and the charge collection in the strip sensor. In the scope of this work, a new edge-TCT setup is commissioned, a procedure for the polishing of the cut edge is implemented and a method to position the focus of the laser light with respect to the sensor is developed. First edge-TCT measurements are performed on non-irradiated, 285 μm thick n-type strip sensors, and the pulse shape and charge collection is studied under different conditions. Furthermore, the prompt current of the transients is extracted, which is the first step towards the determination of the electric field. A new method to measure the attenuation of light in silicon is tested on a non-irradiated sensor and on sensors irradiated with up to a 1 MeV neutron equivalent fluence of 1.14 x 10{sup 15} cm{sup -2}, using laser light with a wavelength of 1052 nm.

Edge-TCT for the investigation of radiation damaged silicon strip sensors

International Nuclear Information System (INIS)

Feindt, Finn

2017-02-01

The edge Transient Current Technique (TCT) is a method for the investigation of silicon sensors. This method requires infrared light from a sub-ns pulsed laser to be focused to a μm-size spot and scanned across the polished cut edge of a sensor. Electron-hole pairs are generated along the light beam in the sensor. These charge carriers drift in the electric field and induce transient currents on the sensor electrodes. The current transients are analyzed as a function of the applied voltage, temperature, absorbed dose and position of the laser-light focus, in order to determine the the drift velocities, electric field and the charge collection in the strip sensor. In the scope of this work, a new edge-TCT setup is commissioned, a procedure for the polishing of the cut edge is implemented and a method to position the focus of the laser light with respect to the sensor is developed. First edge-TCT measurements are performed on non-irradiated, 285 μm thick n-type strip sensors, and the pulse shape and charge collection is studied under different conditions. Furthermore, the prompt current of the transients is extracted, which is the first step towards the determination of the electric field. A new method to measure the attenuation of light in silicon is tested on a non-irradiated sensor and on sensors irradiated with up to a 1 MeV neutron equivalent fluence of 1.14 x 10"1"5 cm"-"2, using laser light with a wavelength of 1052 nm.

High energy X-ray photon counting imaging using linear accelerator and silicon strip detectors

International Nuclear Information System (INIS)

Tian, Y.; Shimazoe, K.; Yan, X.; Ueda, O.; Ishikura, T.; Fujiwara, T.; Uesaka, M.; Ohno, M.; Tomita, H.; Yoshihara, Y.; Takahashi, H.

2016-01-01

A photon counting imaging detector system for high energy X-rays is developed for on-site non-destructive testing of thick objects. One-dimensional silicon strip (1 mm pitch) detectors are stacked to form a two-dimensional edge-on module. Each detector is connected to a 48-channel application specific integrated circuit (ASIC). The threshold-triggered events are recorded by a field programmable gate array based counter in each channel. The detector prototype is tested using 950 kV linear accelerator X-rays. The fast CR shaper (300 ns pulse width) of the ASIC makes it possible to deal with the high instant count rate during the 2 μs beam pulse. The preliminary imaging results of several metal and concrete samples are demonstrated.

High energy X-ray photon counting imaging using linear accelerator and silicon strip detectors

Energy Technology Data Exchange (ETDEWEB)

Tian, Y., E-mail: cycjty@sophie.q.t.u-tokyo.ac.jp [Department of Bioengineering, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Shimazoe, K.; Yan, X. [Department of Nuclear Engineering and Management, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Ueda, O.; Ishikura, T. [Fuji Electric Co., Ltd., Fuji, Hino, Tokyo 191-8502 (Japan); Fujiwara, T. [National Institute of Advanced Industrial Science and Technology, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Uesaka, M.; Ohno, M. [Nuclear Professional School, the University of Tokyo, 2-22 Shirakata-shirane, Tokai, Ibaraki 319-1188 (Japan); Tomita, H. [Department of Quantum Engineering, Nagoya University, Furo, Chikusa, Nagoya 464-8603 (Japan); Yoshihara, Y. [Department of Nuclear Engineering and Management, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Takahashi, H. [Department of Bioengineering, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Department of Nuclear Engineering and Management, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

2016-09-11

A photon counting imaging detector system for high energy X-rays is developed for on-site non-destructive testing of thick objects. One-dimensional silicon strip (1 mm pitch) detectors are stacked to form a two-dimensional edge-on module. Each detector is connected to a 48-channel application specific integrated circuit (ASIC). The threshold-triggered events are recorded by a field programmable gate array based counter in each channel. The detector prototype is tested using 950 kV linear accelerator X-rays. The fast CR shaper (300 ns pulse width) of the ASIC makes it possible to deal with the high instant count rate during the 2 μs beam pulse. The preliminary imaging results of several metal and concrete samples are demonstrated.

Compression of pulsed electron beams for material tests

Science.gov (United States)

Metel, Alexander S.

2018-03-01

In order to strengthen the surface of machine parts and investigate behavior of their materials exposed to highly dense energy fluxes an electron gun has been developed, which produces the pulsed beams of electrons with the energy up to 300 keV and the current up to 250 A at the pulse width of 100-200 µs. Electrons are extracted into the accelerating gap from the hollow cathode glow discharge plasma through a flat or a spherical grid. The flat grid produces 16-cm-diameter beams with the density of transported per one pulse energy not exceeding 15 J·cm-2, which is not enough even for the surface hardening. The spherical grid enables compression of the beams and regulation of the energy density from 15 J·cm-2 up to 15 kJ·cm-2, thus allowing hardening, pulsed melting of the machine part surface with the further high-speed recrystallization as well as an explosive ablation of the surface layer.

The Honeycomb Strip Chamber

International Nuclear Information System (INIS)

Graaf, Harry van der; Buskens, Joop; Rewiersma, Paul; Koenig, Adriaan; Wijnen, Thei

1991-06-01

The Honeycomb Strip Chamber (HSC) is a new position sensitive detector. It consists of a stack of folded foils, forming a rigid honeycomb structure. In the centre of each hexagonal cell a wire is strung. Conducting strips on the foils, perpendicular to the wires, pick up the induced avalanche charge. Test results of a prototype show that processing the signals form three adjacent strips nearest to the track gives a spatial resolution better than 64 μm for perpendicular incident tracks. The chamber performance is only slightly affected by a magnetic field. (author). 25 refs.; 21 figs

Direct current microhollow cathode discharges on silicon devices operating in argon and helium

Science.gov (United States)

Michaud, R.; Felix, V.; Stolz, A.; Aubry, O.; Lefaucheux, P.; Dzikowski, S.; Schulz-von der Gathen, V.; Overzet, L. J.; Dussart, R.

2018-02-01

Microhollow cathode discharges have been produced on silicon platforms using processes usually used for MEMS fabrication. Microreactors consist of 100 or 150 μm-diameter cavities made from Ni and SiO2 film layers deposited on a silicon substrate. They were studied in the direct current operating mode in two different geometries: planar and cavity configuration. Currents in the order of 1 mA could be injected in microdischarges operating in different gases such as argon and helium at a working pressure between 130 and 1000 mbar. When silicon was used as a cathode, the microdischarge operation was very unstable in both geometry configurations. Strong current spikes were produced and the microreactor lifetime was quite short. We evidenced the fast formation of blisters at the silicon surface which are responsible for the production of these high current pulses. EDX analysis showed that these blisters are filled with argon and indicate that an implantation mechanism is at the origin of this surface modification. Reversing the polarity of the microdischarge makes the discharge operate stably without current spikes, but the discharge appearance is quite different from the one obtained in direct polarity with the silicon cathode. By coating the silicon cathode with a 500 nm-thick nickel layer, the microdischarge becomes very stable with a much longer lifetime. No current spikes are observed and the cathode surface remains quite smooth compared to the one obtained without coating. Finally, arrays of 76 and 576 microdischarges were successfully ignited and studied in argon. At a working pressure of 130 mbar, all microdischarges are simultaneously ignited whereas they ignite one by one at higher pressure.

Construction techniques and working principles of external cathode Geiger-Mueller counters

International Nuclear Information System (INIS)

Sevegnani, Francisco Xavier

1996-01-01

In this paper, the construction technique and working principles of the external cathode Geiger-Mueller counter are described in detail. During the analysis of the behavior of these counters a new phenomena was observed, related to an increase int he background rate with the applied voltage. The experiments have also shown that the pulse amplitude of those counters decreases exponentially with the counting rate. The counters built with the techniques described in this paper has shown plateaus of about 1400 V with slope of 0,8%/100 V. (author)

Investigation of the pulsed electrochemical deposition of ZnO

International Nuclear Information System (INIS)

Dunkel, Christian; Lüttich, Franziska; Graaf, Harald; Oekermann, Torsten; Wark, Michael

2012-01-01

The influence of pulse parameters on the morphology of ZnO prepared by pulsed cathodic electrodeposition from oxygen-saturated aqueous ZnCl 2 solution on ITO (indium tin oxide)/glass substrates was investigated. It was found that the ratio between the pulse and the pause duration has a crucial influence on the crystal growth, reaching the highest density of the films with pause/pulse-ratios between 0.25 and 1. Longer pauses cause an Ostwald-like ripening of the ZnO crystals and therewith a strong change in the crystal morphology from roundly shaped to hexagonal. Also the hydrophilicity of the substrate resulting from pre-treatment has a crucial influence on the deposited films, leading to films only consisting of few large and separately grown ZnO crystals for highly hydrophilic substrates and an increasing fraction of small densely grown ZnO crystals with increasing hydrophobicity.

Electron source with the explosion-emission cathode on the base of Bi-Sr-Ca-Cu-O ceramics

International Nuclear Information System (INIS)

Korenev, S.A.

1996-01-01

Two electron sources with explosion-emission cathode on the basis of Bi 2 Sr 2 Ca 2 Cu 3 O x ceramics are described. The scheme of electron gun for formation of electron beams of microsecond length consists of vacuum chamber, flow-passage insulator and cathode with ceramic emitter. The pulse duration by 600 kV voltage equals 1 μs. The split anode, two short magnetic lenses and Rogovsky belt are used for production of low-energy beams. The nanosecond electrical beams with energy of 10-25 keV were produced through this electron source. The beam cross-sectional non-uniformity did not exceed 5% by the beam diameter of 1 cm. 11 refs., 4 figs

Electrochemical behavior of the antituberculosis drug isoniazid and its square-wave adsorptive stripping voltammetric estimation in bulk form, tablets and biological fluids at a mercury electrode.

Science.gov (United States)

Ghoneim, M M; el-Baradie, K Y; Tawfik, A

2003-11-24

Isoniazid, pyridine-4-carboxylic acid hydrazide, is an antituberculosis-agent, which is used to prevent the development of clinical tuberculosis. A validated square-wave adsorptive cathodic stripping voltammetric procedure for the trace determination of the bulk drug at the hanging mercury drop electrode (HMDE) has been developed. Under the optimized conditions, (accumulation potential=-0.9 V, accumulation time=50-300 s, scan increment=8 mV, pulse-amplitude=25 mV, frequency=120 Hz and acetate buffer at pH 5.5) isoniazed generated two irreversible cathodic peaks. The first peak current showed a linear dependence with the drug concentration over the range 5 x 10(-10)-21 x 0(-6) M. The mean percentage recoveries, based on the average of five replicate measurements, for 7 x 10(-9) and 5 x 10(-8) M isoniazid were 97.71+/-2.93 and 99.76+/-0.77, respectively. The achieved limits of detection (LOD) and quantitation (LOQ) were 1.18 x 10(-10) and 3.93 x 10(-10) M isoniazid, respectively. The procedure was applied to the assay of the drug in tablets (Isocid and T.B. Zide), spiked human serum and urine with mean percentage recoveries of 97.81+/-1.49, 97.45+/-2.09, and 97.08+/-1.06, respectively. The limits of detection of 1.47 x 10(-9) and 2.4 x 10(-8) M, and quantitation of 4.9 x 10(-9) and 8 x 10(-8) M drug in human serum and urine, respectively, were achieved. The mean values of the various pharmackinetic parameters of isoniazid (C(max), T(max), t(1/2), AUC, and K(e)), estimated from analysis of plasma of two volunteers by means of the proposed procedure were similar to literature values.

Erosion behavior of composite Al-Cr cathodes in cathodic arc plasmas in inert and reactive atmospheres

Energy Technology Data Exchange (ETDEWEB)

Franz, Robert, E-mail: robert.franz@unileoben.ac.at; Mendez Martin, Francisca; Hawranek, Gerhard [Montanuniversität Leoben, Franz-Josef-Strasse 18, 8700 Leoben (Austria); Polcik, Peter [Plansee Composite Materials GmbH, Siebenbürgerstrasse 23, 86983 Lechbruck am See (Germany)

2016-03-15

Al{sub x}Cr{sub 1−x} composite cathodes with Al contents of x = 0.75, 0.5, and 0.25 were exposed to cathodic arc plasmas in Ar, N{sub 2}, and O{sub 2} atmospheres and their erosion behavior was studied. Cross-sectional analysis of the elemental distribution of the near-surface zone in the cathodes by scanning electron microscopy revealed the formation of a modified layer for all cathodes and atmospheres. Due to intermixing of Al and Cr in the heat-affected zone, intermetallic Al-Cr phases formed as evidenced by x-ray diffraction analysis. Cathode poisoning effects in the reactive N{sub 2} and O{sub 2} atmospheres were nonuniform as a result of the applied magnetic field configuration. With the exception of oxide islands on Al-rich cathodes, reactive layers were absent in the circular erosion zone, while nitrides and oxides formed in the less eroded center region of the cathodes.

Three-electrode pulse electron gun with currents up to 250 A

International Nuclear Information System (INIS)

Grigor'ev, Yu.V.; Shanturin, L.P.

1977-01-01

The design and operating conditions of a pulsed electron gun are described. The electron gun has three electrodes: a cathode, an anode and a control electrode in the form of a grid. The cathode is made from lanthanum hexaboride, which ensures its operation in a low vacuum at a temperature of 1,700 deg C. The control electrode and anode grid are fabricated from sheet tantalum. The anode-grid characteristics of the gun are given. It is shown that at an accelerating voltage of 100 kV, a temperature of 1,700 deg C and a zero control electrode potential the beam current is 250 A

High ion charge states in a high-current, short-pulse, vacuum ARC ion sources

International Nuclear Information System (INIS)

Anders, A.; Brown, I.; MacGill, R.; Dickinson, M.

1996-01-01

Ions of the cathode material are formed at vacuum arc cathode spots and extracted by a grid system. The ion charge states (typically 1-4) depend on the cathode material and only little on the discharge current as long as the current is low. Here the authors report on experiments with short pulses (several μs) and high currents (several kA); this regime of operation is thus approaching a more vacuum spark-like regime. Mean ion charge states of up to 6.2 for tungsten and 3.7 for titanium have been measured, with the corresponding maximum charge states of up to 8+ and 6+, respectively. The results are discussed in terms of Saha calculations and freezing of the charge state distribution

High ion charge states in a high-current, short-pulse, vacuum arc ion source

International Nuclear Information System (INIS)

Anders, A.; Brown, I.; MacGill, R.; Dickinson, M.

1995-09-01

Ions of the cathode material are formed at vacuum arc cathode spots and extracted by a grid system. The ion charge states (typically 1--4) depend on the cathode material and only little on the discharge current as long as the current is low. Here the authors report on experiments with short pulses (several micros) and high currents (several kA); this regime of operation is thus approaching a more vacuum spark-like regime. Mean ion charge states of up to 6.2 for tungsten and 3.7 for titanium have been measured, with the corresponding maximum charge states of up to 8+ and 6+, respectively. The results are discussed in terms of Saha calculations and freezing of the charge state distribution

Selective chemical stripping

Science.gov (United States)

Malavallon, Olivier

1995-04-01

At the end of the 80's, some of the large European airlines expressed a wish for paint systems with improved strippability on their aircraft, allowing the possibility to strip down to the primer without altering it, using 'mild' chemical strippers based on methylene chloride. These improvements were initially intended to reduce costs and stripping cycle times while facilitating rapid repainting, and this without the need to change the conventionally used industrial facilities. The level of in-service performance of these paint systems was to be the same as the previous ones. Requirements related to hygiene safety and the environment were added to these initial requirements. To meet customers' expectations, Aerospatiale, within the Airbus Industry GIE, formed a work group. This group was given the task of specifying, following up the elaboration and qualifying the paint systems allowing requirements to be met, in relation with the paint suppliers and the airlines. The analysis made in this report showed the interest of transferring as far upstream as possible (to paint conception level) most of the technical constraints related to stripping. Thus, the concept retained for the paint system, allowing selective chemical stripping, is a 3-coat system with characteristics as near as possible to the previously used paints.

Charge collection in silicon strip detectors

International Nuclear Information System (INIS)

Kraner, H.W.; Beuttenmuller, R.; Ludlam, T.; Hanson, A.L.; Jones, K.W.; Radeka, V.; Heijne, E.H.M.

1982-11-01

The use of position sensitive silicon detectors as very high resolution tracking devices in high energy physics experiments has been a subject of intense development over the past few years. Typical applications call for the detection of minimum ionizing particles with position measurement accuracy of 10 μm in each detector plane. The most straightforward detector geometry is that in which one of the collecting electrodes is subdivided into closely spaced strips, giving a high degree of segmentation in one coordinate. Each strip may be read out as a separate detection element, or, alternatively, resistive and/or capacitive coupling between adjacent strips may be exploited to interpolate the position via charge division measrurements. With readout techniques that couple several strips, the numer of readout channels can, in principle, be reduced by large factors without sacrificing the intrinsic position accuracy. The testing of individual strip properties and charge division between strips has been carried out with minimum ionizing particles or beams for the most part except in one case which used alphs particless scans. This paper describes the use of a highly collimated MeV proton beam for studies of the position sensing properties of representative one dimensional strip detectors

Synopsis of Cathode No.4 Activation

International Nuclear Information System (INIS)

Kwan, Joe; Ekdahl, C.; Harrison, J.; Kwan, J.; Leitner, M.; McCruistian, T.; Mitchell, R.; Prichard, B.; Roy, P.

2006-01-01

The purpose of this report is to describe the activation of the fourth cathode installed in the DARHT-II Injector. Appendices have been used so that an extensive amount of data could be included without danger of obscuring important information contained in the body of the report. The cathode was a 612 M type cathode purchased from Spectra-Mat. Section II describes the handling and installation of the cathode. Section III is a narrative of the activation based on information located in the Control Room Log Book supplemented with time plots of pertinent operating parameters. Activation of the cathode was performed in accordance with the procedure listed in Appendix A. The following sections provide more details on the total pressure and constituent partial pressures in the vacuum vessel, cathode heater power/filament current, and cathode temperature

Cathode characterization system: preliminary results with (Ba,Sr,Ca) O coated cathodes

International Nuclear Information System (INIS)

Nono, M.C.A.; Goncalves, J.A.N.; Barroso, J.J.; Dallaqua, R.S.; Spassovsky, I.

1993-01-01

The performance of a cathode characterization system for studying the emission parameters of thermal electron emitters is reported. The system consists of vacuum chamber, power supplies and equipment for measuring and control. Measurements have been taken of the emission current as function of cathode temperature and anode voltage. Several (Ba, Sr) O coated cathodes were tested and the results have shown good agreement with Child's and Richardson's laws. The experimental work function is between 1.0 and 2.0 e V. All emission parameters measured are consistent with international literature data. (author)

Research on an improved explosive emission cathode

International Nuclear Information System (INIS)

Liu Guozhi; Sun Jun; Shao Hao; Chen Changhua; Zhang Xiaowei

2009-01-01

This paper presents a physical description of the cathode plasma process of an explosive emission cathode (EEC) and experimental results on a type of oil-immersed graphite EEC. It is believed that the generation of a cathode plasma is mainly dependent on the state of the cathode surface, and that adsorbed gases and dielectrics on the cathode surface play a leading role in the formation of the cathode plasma. Based on these ideas, a type of oil-immersed graphite EEC is proposed and fabricated. The experiments indicate that the oil-immersed cathodes have improved emissive properties and longer lifetimes.

Factors affecting the simultaneous determination of copper, lead, cadmium, and zinc concentrations in human head hair using differential pulse anodic stripping voltammetry method

International Nuclear Information System (INIS)

Wandiga, S.O.; Jumba, I.O.

1982-01-01

Conditions of analysis of copper, lead, cadmium and zinc content in human hair using differential pulse anodic stripping voltammetry (DPASV) and hanging mercury drop electrode (HMDE) have been established. Sample digestion using using the mixture HCI; H 2 O 2 ;HNO 3 in the ratio 2:1:40 by volume gave the best wet-ashing procedure. The peak currents and peak potentials of zinc, cadmium and lead, copper were maximum at pH 6-7 and 1-3 respectively, when excess H 2 O 2 was eliminated with subsequent addition of hydroxyamine hydrochloride. Matrix concentration effects were minimized by digesting weights not exceeding 50 mg per sample. The effect of selenium (IV) was negligible and was ignored. The detection limit of 0.0036 ng/cm 3 for Cd + 2 was obtained while the values for zinc, lead and copper were 0.0230, 0.0287 and 0.0269 ng/cm 3 respectively at the 95% confidence limit. The observed DPASV condition of analysis of these metals are useful for routine determination of the metals in human hair and should complement the conventional flame absorption spectrophotometry method. (author)

Theoretical and experimental study of redox processes combined with adsorption phenomena under conditions of square-wave voltammetry

OpenAIRE

Gulaboski, Rubin

2001-01-01

Theoretical models of four electrode reactions coupled with adsorption phenomena under conditions of square-wave voltammetry are developed: simple surface redox reaction, surface catalytic reaction, cathodic stripping reaction of I order, and cathodic stripping reaction of II order.

Optimizing the Stripping Procedure for LHCb

CERN Document Server

Richardson, Rachel

2017-01-01

The LHCb experiment faces a major challenge from the large amounts of data received while the LHC is running. The ability to sort this information in a useful manner is important for working groups to perform physics analyses. Both hardware and software triggers are used to decrease the data rate and then the stripping process is used to sort the data into streams and further into stripping lines. This project studies the hundreds of stripping lines to look for overlaps between them in order to make the stripping process more efficient.

Characterization of Cs-Sb cathodes for high charge RF photoinjectors

CERN Document Server

AUTHOR|(CDS)2082505; Beghi, Marco

Future accelerators such as CLIC (Compact LInear Collider), require high brightness electron beams that could be produced with a photoinjector (laser-driven electron source). Cs2Te photocathodes in combination with ultra-violet (UV) laser beams are currently used in many photoinjector facilities, but requirements to the electron sources for future accelerators like CLIC are more demanding. The main challenge for the CLIC drive beam photoinjector is to achieve high bunch charges (8.4 nC), high bunch repetition rates (500 MHz) within long trains (140 s) and with suciently long cathode lifetimes. In particular the laser pulse energy in UV, for such long pulse trains, is currently limited due to a degradation of the beam quality during the 4th harmonic frequency conversion process. Using the 2nd harmonic (green laser beam), provided it is matched with a low photoemission threshold photocathode material, would overcome this limitation. Cesium antimonide (Cs3Sb), being a photoemissive material in the visible range,...

Using Comic Strips in Language Classes

Science.gov (United States)

Csabay, Noémi

2006-01-01

The author believes that using comic strips in language-learning classes has three main benefits. First, comic strips motivate younger learners. Second, they provide a context and logically connected sentences to help language learning. Third, their visual information is helpful for comprehension. The author argues that comic strips can be used in…

Composition and Morphology of Product Layers in the Steel/Cement Paste Interface in Conditions of Corrosion and Cathodic Protection in Reinforced Concrete

NARCIS (Netherlands)

Koleva, D.A.; Van Breugel, K.; De Wit, J.H.W.; Fraaij, A.L.A.; Boshkov, N.

2007-01-01

The present study explores the formation of corrosion products on the steel surface in reinforced concrete in conditions of corrosion and subsequent transformation of these layers in conditions of cathodic protection (CP). Of particular interest was to investigate if the introduced pulse CP (as

Test-beam evaluation of heavily irradiated silicon strip modules for ATLAS Phase-II Strip Tracker Upgrade

CERN Document Server

Blue, Andrew; The ATLAS collaboration

2018-01-01

The planned HL-LHC (High Luminosity LHC) is being designed to maximise the physics potential of the LHC with 10 years of operation at instantaneous luminosities of 7.5x1034cm−2s−1. A consequence of this increased luminosity is the expected radiation damage requiring the tracking detectors to withstand hadron equivalences to over 1x1015 1 MeV neutron equivalent per cm2 in the ATLAS Strips system. The silicon strip tracker exploits the concept of modularity. Fast readout electronics, deploying 130nm CMOS front-end electronics are glued on top of a silicon sensor to make a module. The radiation hard n-in-p micro-strip sensors used have been developed by the ATLAS ITk Strip Sensor collaboration and produced by Hamamatsu Photonics. A series of tests were performed at the DESY-II and CERN SPS test beam facilities to investigate the detailed performance of a strip module with both 2.5cm and 5cm length strips before and after irradiation with 8x1014neqcm−2 protons and a total ionising dose of 37.2MRad. The DURA...

Pavement Stripping in Saudi Arabia: Prediction and Prevention

Directory of Open Access Journals (Sweden)

H.I. Al-Abdul Wahhab

2004-12-01

Full Text Available Pavement weathering or stripping is a major distress in highway networks in arid regions. Using the Saudi Arabian road network as a case study area, seventeen road test sections were selected, out of which eight were stripped and nine were non-stripped. Aggregates from quarries used to build these sections were also collected and subjected to detailed physical and chemical tests to evaluate the ability of these tests to distinguish between stripped and non-stripped sections. The modified Lottman test was used to distinguish between compacted mixes. In addition, the Swedish Rolling Bottle test, was also found to be effective in being able to distinguish between different asphalt-aggregates for stripping potential. Eleven anti-stripping liquid additives, lime and cement, in addition to two polymers, were evaluated for their ability to reduce/eliminate stripping potential of stripping-prone aggregates. It was found that EE-2 Polymer, Portland cement, and their combination were effective with all aggregate sources.

Beam loss studies on silicon strip detector modules for the CMS experiment

CERN Document Server

Fahrer, Manuel

2006-01-01

The large beam energy of the LHC demands for a save beam abort system. Nevertheless, failures cannot be excluded with last assurance and are predicted to occur once per year. As the CMS experiment is placed in the neighboured LHC octant, it is affected by such events. The effect of an unsynchronized beam abort on the silicon strip modules of the CMS tracking detector has been investigated in this thesis by performing one accelerator and two lab experiments. The dynamical behaviour of operational parameters of modules and components has been recorded during simulated beam loss events to be able to disentangle the reasons of possible damages. The first study with high intensive proton bunches at the CERN PS ensured the robustness of the module design against beam losses. A further lab experiment with pulsed IR LEDs clarified the physical and electrical processes during such events. The silicon strip sensors on a module are protected against beam losses by a part of the module design that originally has not been...

Compact multiwire proportional chambers and electronics for the crystal ball detector

International Nuclear Information System (INIS)

Gaiser, J.E.; Liberman, A.D.; Rolfe, J.

1978-01-01

A double gap of cylindrical proportional chambers has been designed and built for use with a large solid angle, modular NaI(Tl) array (The Crystal Ball). The chambers are constructed of three coaxial foam-epoxy shells, covered with an aluminum-mylar laminate. One of the high voltage cathodes in each chamber has been photo-etched to produce a pattern of stripes and precise position measurements of tracks passing transverse to the chamber axis are found by pulse height analyzing the shaped and amplified induced strip signals. Performance of the chamber using both the strip signals and the sense wire readout is presented. The design of both the signal handling electronics and the digital portions of the systems is discussed

Synthesis of Ti-doped DLC film on SS304 steels by Filtered Cathodic Vacuum Arc (FCVA) technique for tribological improvement

Science.gov (United States)

Bootkul, D.; Saenphinit, N.; Supsermpol, B.; Aramwit, C.; Intarasiri, S.

2014-08-01

Currently, stainless steels are widely used in various industrial applications due to their excellence in toughness and corrosion resistance. But their resistance to wear needs to be improved for appropriate use in tribological applications. The Filtered Cathodic Vacuum Arc (FCVA) is a superior technique for forming a high-density film structure of amorphous carbon, especially for a tetrahedral amorphous carbon (ta-C) type, because it can produce a plasma of highly energetic ions that can penetrate into a growing coating, resulting in densification of the film. However, this technique tends to generate high internal stress, due to serious accumulation of energy in the film structure that then leads to film delamination. In general, there are numerous solutions that have been used to reduce the internal stress. DLC with various additive elements such as Ti, Cr or W as strong-carbide-forming (SCF) metals is one of the popular methods to provide attractive combinations of properties of wear resistance and film adhesion as well as reducing the internal stress. The present study was focused on investigation of titanium-doped DLC coating on SS304 steel, mainly for adhesion improvement in optimizing for tribological applications. The synthesized films were formed by the FCVA technique at normal substrate temperature. In the experimental set-up, the films were produced by mixing the titanium and carbon ions generated by dual cathode plasma source operating in synchronous pulsed mode. Their compositions were adjusted by varying the relative duration of the pulse length from each cathode. Titanium doping concentration was varied from pure DLC deposition as the control group to titanium and graphite trigger pulses ratios of 1:16, 1:12, 1:10, 1:8 and 1:4, as the Ti-doped DLC group. The results showed that by increasing titanium trigger pulses ratio from 1:16, 1:12, 1:10 and 1:8, respectively, the film adhesion was increased while the wear rate did not change significantly as

Nanosecond field emitted and photo-field emitted current pulses from ZrC tips

International Nuclear Information System (INIS)

Ganter, R.; Bakker, R.J.; Gough, C.; Paraliev, M.; Pedrozzi, M.; Le Pimpec, F.; Rivkin, L.; Wrulich, A.

2006-01-01

In order to find electron sources with low thermal emittance, cathodes based on single tip field emitter are investigated. Maximum peak current, measured from single tip in ZrC with a typical apex radius around 1 μm, are presented. Voltage pulses of 2 ns duration and up to 50 kV amplitude lead to field emission current up to 470 mA from one ZrC tip. Combination of high applied electric field with laser illumination gives the possibility to modulate the emission with laser pulses. Nanoseconds current pulses have been emitted with laser pulses at 1064 nm illuminating a ZrC tip under high-DC electric field. The dependence of photo-field emitted current with the applied voltage can be explained by the Schottky effect

Nanosecond field emitted and photo-field emitted current pulses from ZrC tips

Energy Technology Data Exchange (ETDEWEB)

Ganter, R. [Paul Scherrer Institut, Villigen, CH 5232 (Switzerland)]. E-mail: romain.ganter@psi.ch; Bakker, R.J. [Paul Scherrer Institut, Villigen, CH 5232 (Switzerland); Gough, C. [Paul Scherrer Institut, Villigen, CH 5232 (Switzerland); Paraliev, M. [Paul Scherrer Institut, Villigen, CH 5232 (Switzerland); Pedrozzi, M. [Paul Scherrer Institut, Villigen, CH 5232 (Switzerland); Le Pimpec, F. [Paul Scherrer Institut, Villigen, CH 5232 (Switzerland); Rivkin, L. [Paul Scherrer Institut, Villigen, CH 5232 (Switzerland); Wrulich, A. [Paul Scherrer Institut, Villigen, CH 5232 (Switzerland)

2006-09-15

In order to find electron sources with low thermal emittance, cathodes based on single tip field emitter are investigated. Maximum peak current, measured from single tip in ZrC with a typical apex radius around 1 {mu}m, are presented. Voltage pulses of 2 ns duration and up to 50 kV amplitude lead to field emission current up to 470 mA from one ZrC tip. Combination of high applied electric field with laser illumination gives the possibility to modulate the emission with laser pulses. Nanoseconds current pulses have been emitted with laser pulses at 1064 nm illuminating a ZrC tip under high-DC electric field. The dependence of photo-field emitted current with the applied voltage can be explained by the Schottky effect.

Air humidity and water pressure effects on the performance of air-cathode microbial fuel cell cathodes

KAUST Repository

Ahn, Yongtae

2014-02-01

To better understand how air cathode performance is affected by air humidification, microbial fuel cells were operated under different humidity conditions or water pressure conditions. Maximum power density decreased from 1130 ± 30 mW m-2 with dry air to 980 ± 80 mW m -2 with water-saturated air. When the cathode was exposed to higher water pressures by placing the cathode in a horizontal position, with the cathode oriented so it was on the reactor bottom, power was reduced for both with dry (1030 ± 130 mW m-2) and water-saturated (390 ± 190 mW m-2) air. Decreased performance was partly due to water flooding of the catalyst, which would hinder oxygen diffusion to the catalyst. However, drying used cathodes did not improve performance in electrochemical tests. Soaking the cathode in a weak acid solution, but not deionized water, mostly restored performance (960 ± 60 mW m-2), suggesting that there was salt precipitation in the cathode that was enhanced by higher relative humidity or water pressure. These results showed that cathode performance could be adversely affected by both flooding and the subsequent salt precipitation, and therefore control of air humidity and water pressure may need to be considered for long-term MFC operation. © 2013 Elsevier B.V. All rights reserved.

Stabilization of a cold cathode electron beam glow discharge for surface treatment

International Nuclear Information System (INIS)

Mingolo, N.; Gonzalez, C.R.; Martinez, O.E.; Rocca, J.J.

1997-01-01

We have demonstrated that the reproducibility of electron beam pulses generated by a high power, cold cathode glow discharge is greatly improved by adding a small continuous keep-alive discharge current. A current of the order of 200 μA was found to limit the shot to shot current variation to within 1.5%. This stabilization in turn reduces by an order of magnitude the fluctuations of the energy density deposited on the target, demonstrating a reliable energy source for surface treatment. copyright 1997 American Institute of Physics

Stabilization of a cold cathode electron beam glow discharge for surface treatment

Energy Technology Data Exchange (ETDEWEB)

Mingolo, N.; Gonzalez, C.R. [Lab. de Haces Dirigidos, Depto. de Fisica, Facultad de Ingenieria, Universidad de Buenos Aires, Paseo Colon 850, 1063 Buenos Aires (Argentina); Martinez, O.E. [Lab. de Electronica Cuantica, Depto. de Fisica, Universidad de Buenos Aires, Pabellon 1, Ciudad Universitaria, 1428 Buenos Aires (Argentina); Rocca, J.J. [Department of Electrical Engineering, Colorado State University, Fort Collins, Colorado 80523 (United States)

1997-10-01

We have demonstrated that the reproducibility of electron beam pulses generated by a high power, cold cathode glow discharge is greatly improved by adding a small continuous keep-alive discharge current. A current of the order of 200 {mu}A was found to limit the shot to shot current variation to within 1.5{percent}. This stabilization in turn reduces by an order of magnitude the fluctuations of the energy density deposited on the target, demonstrating a reliable energy source for surface treatment. {copyright} {ital 1997 American Institute of Physics.}

Annular-cathode electron gun for in-line injection in a racetrack microtron

International Nuclear Information System (INIS)

Manca, J.J.; Edmonds, D.S. Jr.; Froelich, H.R.

1976-01-01

A compact annular-cathode electron gun which allows direct, efficient injection into the accelerating structure of a racetrack microtron was designed, built, and tested. The gun operates under pulsed conditions with applied high voltages of 40 kV or more and delivers an output current in excess of 1 A. Design and construction details are presented for both a basic gun and a gun with built-in output current monitor. Gun performance in a test chamber and in the multicavity racetrack microtron at the University of Western Ontario is described

Cathode material for lithium batteries

Science.gov (United States)

Park, Sang-Ho; Amine, Khalil

2013-07-23

A method of manufacture an article of a cathode (positive electrode) material for lithium batteries. The cathode material is a lithium molybdenum composite transition metal oxide material and is prepared by mixing in a solid state an intermediate molybdenum composite transition metal oxide and a lithium source. The mixture is thermally treated to obtain the lithium molybdenum composite transition metal oxide cathode material.

Cathode erosion in a high-pressure high-current arc: calculations for tungsten cathode in a free-burning argon arc

International Nuclear Information System (INIS)

Nemchinsky, Valerian

2012-01-01

The motion of an evaporated atom of the cathode material in a near-cathode plasma is considered. It is shown that the evaporated atom is ionized almost instantly. The created ion, under the influence of a strong electric field existing in the cathode proximity, has a high probability of returning to the cathode. A small fraction of evaporated atoms are able to diffuse away from the cathode to the region where they are involved in plasma flow and lose their chance to return to the cathode. The fraction of the total evaporated atoms, which do not return to the cathode, the escape factor, determines the net erosion rate. In order to calculate this factor, the distributions of the plasma parameters in the near-cathode plasma were considered. Calculations showed that the escape factor is on the order of a few per cent. Using experimental data on the plasma and cathode temperatures, we calculated the net erosion rate for a free-burning 200 A argon arc with a thoriated tungsten cathode. The calculated erosion rate is close to 1 µg s -1 , which is in agreement with available experimental data. (paper)

The effect of cathode geometry on barium transport in hollow cathode plasmas

International Nuclear Information System (INIS)

Polk, James E.; Mikellides, Ioannis G.; Katz, Ira; Capece, Angela M.

2014-01-01

The effect of barium transport on the operation of dispenser hollow cathodes was investigated in numerical modeling of a cathode with two different orifice sizes. Despite large differences in cathode emitter temperature, emitted electron current density, internal xenon neutral and plasma densities, and size of the plasma-surface interaction region, the barium transport in the two geometries is qualitatively very similar. Barium is produced in the insert and flows to the surface through the porous structure. A buildup of neutral Ba pressure in the plasma over the emitter surface can suppress the reactions supplying the Ba, restricting the net production rate. Neutral Ba flows into the dense Xe plasma and has a high probability of being ionized at the periphery of this zone. The steady state neutral Ba density distribution is determined by a balance between pressure gradient forces and the drag force associated with collisions between neutral Ba and neutral Xe atoms. A small fraction of the neutral Ba is lost upstream. The majority of the neutral Ba is ionized in the high temperature Xe plasma and is pushed back to the emitter surface by the electric field. The steady state Ba + ion density distribution results from a balance between electrostatic and pressure forces, neutral Xe drag and Xe + ion drag with the dominant forces dependent on location in the discharge. These results indicate that hollow cathodes are very effective at recycling Ba within the discharge and therefore maintain a high coverage of Ba on the emitter surface, which reduces the work function and sustains high electron emission current densities at moderate temperatures. Barium recycling is more effective in the cathode with the smaller orifice because the Ba is ionized in the dense Xe plasma concentrated just upstream of the orifice and pushed back into the hollow cathode. Despite a lower emitter temperature, the large orifice cathode has a higher Ba loss rate through the orifice because the Xe

Electron Emission And Beam Generation Using Ferroelectric Cathodes (electron Beam Generation, Lead Lanthanum Zicronate Titanate, High Power Traveling Wave Tube Amplfier)

CERN Document Server

Flechtner, D D

1999-01-01

In 1989, researchers at CERN published the discovery of significant electron emission (1– 100 A/cm2) from Lead- Lanthanum-Zirconate-Titanate (PLZT). The publication of these results led to international interest in ferroelectric cathodes studies for use in pulsed power devices. At Cornell University in 1991, experiments with Lead-Zirconate-Titanate (PZT) compositions were begun to study the feasibility of using this ferroelectric material as a cathode in the electron gun section of High Power Traveling Wave Tube Amplifier Experiments. Current-voltage characteristics were documented for diode voltages ranging from 50– 500,000 V with anode cathode gaps of.5– 6 cm. A linear current-voltage relation was found for voltages less than 50 kV. For diode voltages ≥ 200 kV, a typical Child-Langmuir V3/2 dependence was observed...

Performance of novel moderator for pulsed neutron diffraction

International Nuclear Information System (INIS)

Mayer, R.E.; Granada, J.R.; Dawidowski, J.; Gillette, V.H.

1991-01-01

Measurements of neutron pulse time-width and intensity have been carried out on grids of small moderators placed side by side and decoupled by cadmium strips. This moderator concept had been introduced at ICANS-10. The present measurements explore greater moderator thicknesses than those previously attained, yielding information on thickness optimization, while confirming the previous results on resolution which make this moderator a favourable choice in front of the conventional sandwich set-up. (author)

Cathodic protection -- Rectifier 47

International Nuclear Information System (INIS)

Lane, W.M.

1995-01-01

This Acceptance Test Procedure (ATP) has been prepared to demonstrate that the cathodic protection system functions as required by project criteria. The cathodic protection system is for the tank farms at the Hanford Reservation. The tank farms store radioactive waste

Cathodic protection -- Rectifier 46

International Nuclear Information System (INIS)

Lane, W.M.

1995-01-01

This Acceptance Test Procedure (ATP) has been prepared to demonstrate that the cathodic protection system functions as required by project criteria. The cathodic protection system is for the tank farms on the Hanford Reservation. The tank farms store radioactive waste

Cathode R&D for Future Light Sources

Energy Technology Data Exchange (ETDEWEB)

Dowell, D.H.; /SLAC; Bazarov, I.; Dunham, B.; /Cornell U., CLASSE; Harkay, K.; /Argonne; Hernandez-Garcia; /Jefferson Lab; Legg, R.; /Wisconsin U., SRC; Padmore, H.; /LBL, Berkeley; Rao, T.; Smedley, J.; /Brookhaven; Wan, W.; /LBL, Berkeley

2010-05-26

This paper reviews the requirements and current status of cathodes for accelerator applications, and proposes a research and development plan for advancing cathode technology. Accelerator cathodes need to have long operational lifetimes and produce electron beams with a very low emittance. The two principal emission processes to be considered are thermionic and photoemission with the photocathodes being further subdivided into metal and semi-conductors. Field emission cathodes are not included in this analysis. The thermal emittance is derived and the formulas used to compare the various cathode materials. To date, there is no cathode which provides all the requirements needed for the proposed future light sources. Therefore a three part research plan is described to develop cathodes for these future light source applications.

Mechanistic Enhancement of SOFC Cathode Durability

Energy Technology Data Exchange (ETDEWEB)

Wachsman, Eric [Univ. of Maryland, College Park, MD (United States)

2016-02-01

Durability of solid oxide fuel cells (SOFC) under “real world” conditions is an issue for commercial deployment. In particular cathode exposure to moisture, CO2, Cr vapor (from interconnects and BOP), and particulates results in long-term performance degradation issues. Here, we have conducted a multi-faceted fundamental investigation of the effect of these contaminants on cathode performance degradation mechanisms in order to establish cathode composition/structures and operational conditions to enhance cathode durability.

International comparison of Cd content in a quality control material of Navajuelas (Tagelus dombeii) determined by anodic stripping voltammetry, atomic absorption spectrometry and neutron activation analysis

International Nuclear Information System (INIS)

Queirolo, F.; Forschungszentrum Juelich GmbH; Universidad de Extremadura, Badajoz; Ostapczuk, P.; Valenta, P.; Stegen, S.; Universidad de Extremadura, Badajoz; Marin, C.; Vinagre, F.; Sanchez, A.

1991-01-01

The determination of Cd was performed by neutron activation analysis (NAA), atomic absorption spectrometry (AAS) with flame or in the electrothermal mode and anodic stripping voltammetry in the differential pulse mode (DPASV) and the square wave mode (SWASV). (orig./EF)

Two-beam virtual cathode accelerator

International Nuclear Information System (INIS)

Peter, W.

1992-01-01

A proposed method to control the motion of a virtual cathode is investigated. Applications to collective ion acceleration and microwave generation are indicated. If two counterstreaming relativistic electron beams of current I are injected into a drift tube of space-charge-limiting current I L = 2I, it is shown that one beam can induce a moving virtual cathode in the other beam. By dynamically varying the current injected into the drift tube region, the virtual cathode can undergo controlled motion. For short drift tubes, the virtual cathodes on each end are strongly-coupled and undergo coherent large-amplitude spatial oscillations within the drift tube

The noise analysis and optimum filtering techniques for a two-dimensional position sensitive orthogonal strip gamma ray detector employing resistive charge division

International Nuclear Information System (INIS)

Gerber, M.S.; Muller, D.W.

1976-01-01

The analysis of an orthogonal strip, two-dimensional position sensitive high purity germanium gamma ray detector is discussed. Position sensitivity is obtained by connecting each electrode strip on the detector to a resistor network. Charge, entering the network, divides in relation to the resistance between its entry point and the virtual earth points of the charge sensitive preamplifiers located at the end of each resistor network. The difference of the voltage pulses at the output of each preamplifier is proportional to the position at which the charge entered the resistor network and the sum of the pulse is proportional to the energy of the detected gamma ray. The analysis and spatial noise resolution is presented for this type of position sensitive detector. The results of the analysis show that the position resolution is proportional to the square root of the filter amplifier's output pulse time constant and that for energy measurement the resolution is maximized at the filter amplifier's noise corner time constant. The design of the electronic noise filtering system for the prototype gamma ray camera was based on the mathematical energy and spatial resolution equations. For the spatial channel a Gaussian trapezoidal filtering system was developed. Gaussian filtering was used for the energy channel. The detector noise model was verified by taking rms noise measurements of the filtered energy and spatial pulses from resistive readout charge dividing detectors. These measurements were within 10% of theory. (Auth.)

Large-area cold-cathode grid-controlled electron gun for Antares

International Nuclear Information System (INIS)

Scarlett, W.R.; Andrews, K.; Jansen, J.

1979-01-01

The CO 2 laser amplifiers used in the Antares inertial confinement fusion project require large-area radial beams of high-energy electrons to ionize the laser medium before the main discharge pulse is applied. We have designed a grid-controlled, cold-cathode electron gun with a cylindrical anode having a window area of 9.3 m 2 . A full diameter, 1/4 length prototype of the Antares gun has been built and tested. The design details of the Antares electron gun will be presented as well as test results from the prototype. Techniques used for the prevention and control of emission and breakdown from the grid will also be discussed

Deposition of hematite Fe.sub.2./sub.O.sub.3./sub. thin film by DC pulsed magnetron and DC pulsed hollow cathode sputtering system

Czech Academy of Sciences Publication Activity Database

Hubička, Zdeněk; Kment, Štěpán; Olejníček, Jiří; Čada, Martin; Kubart, T.; Brunclíková, Michaela; Kšírová, Petra; Adámek, Petr; Remeš, Zdeněk

2013-01-01

Roč. 549, Dec (2013), s. 184-191 ISSN 0040-6090 R&D Projects: GA ČR GAP108/12/2104; GA MŠk LH12043 Grant - others:AVČR(CZ) M100101215 Institutional support: RVO:68378271 Keywords : HIPIMS * thin films * hollow cathode Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.867, year: 2013

Electron emission from pseudospark cathodes

International Nuclear Information System (INIS)

Anders, A.; Anders, S.; Gundersen, M.A.

1994-01-01

The pseudospark cathode has the remarkable property of macroscopically homogeneous electron emission at very high current density (>1 kA/cm 2 ) over a large area (some cm 2 ). The model of electron emission presented here is based on the assumption that the pseudospark microscopically utilizes explosive arc processes, as distinct from earlier models of ''anomalous emission in superdense glow discharges.'' Explosive emission similar to vacuum are cathode spots occurs rapidly when the field strength is sufficiently high. The plasma remains macroscopically homogeneous since the virtual plasma anode adapts to the cathode morphology so that the current is carried by a large number of homogeneously distributed cathode spots which are similar to ''type 1'' and ''type 2'' spots of vacuum arc discharges. The net cathode erosion is greatly reduced relative to ''spark gap-type'' emission. At very high current levels, a transition to highly erosive spot types occurs, and this ''arcing'' leads to a significant reduction in device lifetime. Assuming vacuum-arc-like cathode spots, the observed current density and time constants can be easily explained. The observed cathode erosion rate and pattern, recent fast-camera data, laser-induced fluorescence, and spectroscopic measurements support this approach. A new hypothesis is presented explaining current quenching at relatively low currents. From the point of view of electron emission, the ''superdense glow'' or ''superemissive phase'' of pseudosparks represents an arc and not a glow discharge even if no filamentation or ''arcing'' is observed

Elemental redistribution in coloured films on SUS304 stainless steel produced by current pulse method

International Nuclear Information System (INIS)

Lin, C.J.; Duh, J.G.

1996-01-01

Coloured films are deposited on an SUS304 substrate by the square wave current pulse method in a 2.5 M CrO 3 + 5 M H 2 SO 4 solution at 75 C. The absolute ratio of anodic to cathodic charge density and the corresponding final value of cathodic potential provide an easy and appropriate approach to the control of colour in the current pulse colouring method. This is proved in this study for a frequency region lower than 1 Hz. The corresponding cathodic potential increases with increasing dwell time in the negative applied current region and is related to the colour tone of the deposited film. The total time required to obtain the same thickness of coloured film is shorter at lower frequency than at higher frequency, which takes more time to charge the double layer. The thickness of the coloured films is determined by both Auger electron spectroscopy (AES) and secondary ion mass spectrometry (SIMS) depth profiling and is of submicron order. The film thickness is proportional to the introduced total charge per unit area in the current pulse colouring process. CrO + and FeO + ions are observed in the coloured films and their concentrations increase as the colouring time is increased. The Fe concentration in the coloured films is lower than that in the substrate and decreases with the colouring time. It is the iron species that first becomes involved in the anodic reaction and the spinel oxide structure of iron and chromium is present in the coloured films. (orig.)

Large strip RPCs for the LEPS2 TOF system

Energy Technology Data Exchange (ETDEWEB)

Tomida, N., E-mail: natsuki@scphys.kyoto-u.ac.jp [Department of Physics, Kyoto University, Kyoto 606-8502 (Japan); Niiyama, M. [Department of Physics, Kyoto University, Kyoto 606-8502 (Japan); Ohnishi, H. [RIKEN (The Institute of Physical and Chemical Research), Wako, Saitama 351-0198 (Japan); Tran, N. [Research Center for Nuclear Physics (RCNP), Osaka University, Ibaraki, Osaka 567-0047 (Japan); Hsieh, C.-Y.; Chu, M.-L.; Chang, W.-C. [Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan (China); Chen, J.-Y. [National Synchrotron Radiation Research Center (NSRRC), Hsinchu 30076, Taiwan (China)

2014-12-01

High time-resolution resistive plate chambers (RPCs) with large-size readout strips are developed for the time-of-flight (TOF) detector system of the LEPS2 experiment at SPring-8. The experimental requirement is a 50-ps time resolution for a strip size larger than 100 cm{sup 2}/channel. We are able to achieve 50-ps time resolutions with 2.5×100 cm{sup 2} strips by directly connecting the amplifiers to strips. With the same time resolution, the number of front-end electronics (FEE) is also reduced by signal addition. - Highlights: • Find a way to achieve a good time resolution with a large strip RPC. • 2.5 cm narrow strips have better resolutions than 5.0 cm ones. • The 0.5 mm narrow strip interval shows flat time resolutions between strips. • FEEs directly connected to strips make the signal reflection at the strip edge small. • A time resolution of 50 ps was achieved with 2.5 cm×100 cm strips.

Cold cathode arc model in mercury discharges

International Nuclear Information System (INIS)

Li, Y.M.; Byszewski, W.W.; Budinger, A.B.

1990-01-01

Voltage/current characteristics measured during the starting of metal halide lamps indicate a low voltage discharge when condensates (mainly mercury) are localized on the electrodes. In this case, even with a cold cathode which does not emit electrons, the current is very high and voltage across the lamp drops to about 15 to 20 V. This type of discharge is similar to the cold cathode mercury vapor arc found in mercury pool rectifiers. The cathode sheath in the mercury vapor arc is characterized by very small cathode spot size, on the order of 10 -c cm 2 , very high current density of about 10 6 A/cm 2 and very low cathode fall of approximately 10 volts. The discharge is modified and generalized to describe the cathode phenomena in the cold cathode mercury vapor arc. The sensitivity of calculated discharge parameters with respect to such modifications were examined. Results show that the cathode fall voltage remains fairly constant (7-8 volts) with large fractional variations of metastable mercury atoms bombarding the cathode. This result compares very well with experimental waveforms when anode fall and plasma voltage approximations are incorporated

Nano-scale investigations of electric-dipole-layer enhanced field and thermionic emission from high current density cathodes

Science.gov (United States)

Vlahos, Vasilios

Cesium iodide coated graphitic fibers and scandate cathodes are two important electron emission technologies. The coated fibers are utilized as field emitters for high power microwave sources. The scandate cathodes are promising thermionic cathode materials for pulsed power vacuum electron devices. This work attempts to understand the fundamental physical and chemical relationships between the atomic structure of the emitting cathode surfaces and the superior emission characteristics of these cathodes. Ab initio computational modeling in conjunction with experimental investigations was performed on coated fiber cathodes to understand the origin of their very low turn on electric field, which can be reduced by as much as ten-fold compared to uncoated fibers. Copious amounts of cesium and oxygen were found co-localized on the fiber, but no iodine was detected on the surface. Additional ab initio studies confirmed that cesium oxide dimers could lower the work function significantly. Surface cesium oxide dipoles are therefore proposed as the source of the observed reduction in the turn on electric field. It is also proposed that emission may be further enhanced by secondary electrons from cesium oxide during operation. Thermal conditioning of the coated cathode may be a mechanism by which surface cesium iodide is converted into cesium oxide, promoting the depletion of iodine by formation of volatile gas. Ab initio modeling was also utilized to investigate the stability and work functions of scandate structures. The work demonstrated that monolayer barium-scandium-oxygen surface structures on tungsten can dramatically lower the work function of the underlying tungsten substrate from 4.6 eV down to 1.16 eV, by the formation of multiple surface dipoles. On the basis of this work, we conclude that high temperature kinetics force conventional dispenser cathodes (barium-oxygen monolayers on tungsten) to operate in a non-equilibrium compositional steady state with higher than

Mechanical behaviour of a creased thin strip

Directory of Open Access Journals (Sweden)

J. Liu

2018-02-01

Full Text Available In this study the mechanical behaviour of a creased thin strip under opposite-sense bending was investigated. It was found that a simple crease, which led to the increase of the second moment of area, could significantly alter the overall mechanical behaviour of a thin strip, for example the peak moment could be increased by 100 times. The crease was treated as a cylindrical segment of a small radius. Parametric studies demonstrated that the geometry of the strip could strongly influence its flexural behaviour. We showed that the uniform thickness and the radius of the creased segment had the greatest and the least influence on the mechanical behaviour, respectively. We further revealed that material properties could dramatically affect the overall mechanical behaviour of the creased strip by gradually changing the material from being linear elastic to elastic-perfect plastic. After the formation of the fold, the moment of the two ends of the strip differed considerably when the elasto-plastic materials were used, especially for materials with smaller tangent modulus in the plastic range. The deformation patterns of the thin strips from the finite element simulations were verified by physical models made of thin metal strips. The findings from this study provide useful information for designing origami structures for engineering applications using creased thin strips.

TH-CD-207B-01: BEST IN PHYSICS (IMAGING): Development of High Brightness Multiple-Pixel X-Ray Source Using Oxide Coated Cathodes

Energy Technology Data Exchange (ETDEWEB)

Kandlakunta, P; Pham, R; Zhang, T [Washington University School of Medicine, St. Louis, MO (United States)

2016-06-15

Purpose: To develop and characterize a high brightness multiple-pixel thermionic emission x-ray (MPTEX) source. Methods: Multiple-pixel x-ray sources allow for designs of novel x-ray imaging techniques, such as fixed gantry CT, digital tomosynthesis, tetrahedron beam computed tomography, etc. We are developing a high-brightness multiple-pixel thermionic emission x-ray (MPTEX) source based on oxide coated cathodes. Oxide cathode is chosen as the electron source due to its high emission current density and low operating temperature. A MPTEX prototype has been developed which may contain up to 41 micro-rectangular oxide cathodes in 4 mm pixel spacing. Electronics hardware was developed for source control and switching. The cathode emission current was evaluated and x-ray measurements were performed to estimate the focal spot size. Results: The oxide cathodes were able to produce ∼110 mA cathode current in pulse mode which corresponds to an emission current density of 0.55 A/cm{sup 2}. The maximum kVp of the MPTEX prototype currently is limited to 100 kV due to the rating of high voltage feedthrough. Preliminary x-ray measurements estimated the focal spot size as 1.5 × 1.3 mm{sup 2}. Conclusion: A MPTEX source was developed with thermionic oxide coated cathodes and preliminary source characterization was successfully performed. The MPTEX source is able to produce an array of high brightness x-ray beams with a fast switching speed.

TH-CD-207B-01: BEST IN PHYSICS (IMAGING): Development of High Brightness Multiple-Pixel X-Ray Source Using Oxide Coated Cathodes

International Nuclear Information System (INIS)

Kandlakunta, P; Pham, R; Zhang, T

2016-01-01

Purpose: To develop and characterize a high brightness multiple-pixel thermionic emission x-ray (MPTEX) source. Methods: Multiple-pixel x-ray sources allow for designs of novel x-ray imaging techniques, such as fixed gantry CT, digital tomosynthesis, tetrahedron beam computed tomography, etc. We are developing a high-brightness multiple-pixel thermionic emission x-ray (MPTEX) source based on oxide coated cathodes. Oxide cathode is chosen as the electron source due to its high emission current density and low operating temperature. A MPTEX prototype has been developed which may contain up to 41 micro-rectangular oxide cathodes in 4 mm pixel spacing. Electronics hardware was developed for source control and switching. The cathode emission current was evaluated and x-ray measurements were performed to estimate the focal spot size. Results: The oxide cathodes were able to produce ∼110 mA cathode current in pulse mode which corresponds to an emission current density of 0.55 A/cm 2 . The maximum kVp of the MPTEX prototype currently is limited to 100 kV due to the rating of high voltage feedthrough. Preliminary x-ray measurements estimated the focal spot size as 1.5 × 1.3 mm 2 . Conclusion: A MPTEX source was developed with thermionic oxide coated cathodes and preliminary source characterization was successfully performed. The MPTEX source is able to produce an array of high brightness x-ray beams with a fast switching speed.

Several peaks of total current in Trichel pulse

International Nuclear Information System (INIS)

Bolotov, O.; Golota, V.; Kadolin, B.; Mankovskyi, S.; Ostroushko, V.; Pashchenko, I.; Taran, G.; Zavada, L.

2015-01-01

The numerical simulations of negative corona at constant voltage in Trichel pulse mode are carried out in assumptions of presence and absence of photoemission from cathode. In absence of photoemission two peaks of total current or the step before the main peak were obtained for very small values of ion-electron emission coefficient. In presence of photoemission there were observed several maximums, connected with instability development of the process based on radiation of photons, photoemission, and avalanche multiplication

Experimental progress on virtual-cathode very high power microwave source development

International Nuclear Information System (INIS)

Fazio, M.V.; Hoeberling, R.F.

1987-01-01

The evolution of rf accelerator technology toward high-power, high-current, low-emittance beams produces an ever-increasing demand for efficient, very high power microwave sources. The present klystron technology has performed very well but is not expected to produce reliable gigawatt peak-power units in the 1- to 10-GHz regime. Further major advancements must involve other types of sources. The reflexing electron sources can produce microwave powers at the gigawatt level and have demonstrated operation from 800 MHz to 40 GHz. Pulse length appears to be limited by electron-beam diode closure, and reflexing electron devices have been operated in a repetitively pulsed mode. An experiment is under way to investigate concepts to stabilize the frequency of the virtual cathode source. If one can successfully frequency and phase lock this source to an external signal, then this source can operate as a very high power microwave amplifier making it practical for accelerator applications. The progress on an experiment to test these concepts will be discussed

Comparative limnology of strip-mine lakes

Energy Technology Data Exchange (ETDEWEB)

Parsons, J D

1964-01-01

Lakes were classified according to chemical properties. The concentration of the ferric iron oxides was responsible for a reddish-black turbidity which, in turn, played a major role in the thermal stratification of red strip-mine lakes. Owing to the lack of measurable turbidity and as a result of selective absorption of visible solar radiation, other strip-mine lakes appeared blue in color. The annual heat budget and the summer heat budget are essentially equivalent under saline conditions. Regardless of the physical and chemical conditions of the strip-mine lakes, heat income was a function of the circulating water mass. The progressive oxidation and precipitation of the iron oxides is the key to the classification of strip-mine lakes.

Plasma processes inside dispenser hollow cathodes

International Nuclear Information System (INIS)

Mikellides, Ioannis G.; Katz, Ira; Goebel, Dan M.; Polk, James E.; Jameson, Kristina K.

2006-01-01

A two-dimensional fluid model of the plasma and neutral gas inside dispenser orificed hollow cathodes has been developed to quantify plasma processes that ultimately determine the life of the porous emitters inserted in these devices. The model self-consistently accounts for electron emission from the insert as well as for electron and ion flux losses from the plasma. Two cathodes, which are distinctively different in size and operating conditions, have been simulated numerically. It is found that the larger cathode, with outer tube diameter of 1.5 cm and orifice diameter of 0.3 cm, establishes an effective emission zone that spans approximately the full length of the emitter when operated at a discharge current of 25 A and a flow rate of 5.5 sccm. The net heating of the emitter is caused by ions that are produced by ionization of the neutral gas inside the tube and are then accelerated by the sheath along the emitter. The smaller cathode, with an outer diameter of 0.635 cm and an orifice diameter of 0.1 cm, does not exhibit the same operational characteristics. At a flow rate of 4.25 sccm and discharge current of 12 A, the smaller cathode requires 4.5 times the current density near the orifice and operates with more than 6 times the neutral particle density compared to the large cathode. As a result, the plasma particle density is almost one order of magnitude higher compared to the large cathode. The plasma density in this small cathode is high enough such that the Debye length is sufficiently small to allow 'sheath funneling' into the pores of the emitter. By accessing areas deeper into the insert material, it is postulated that the overall emission of electrons is significantly enhanced. The maximum emission current density is found to be about 1 A/mm 2 in the small cathode, which is about one order of magnitude higher than attained in the large cathode. The effective emission zone in the small cathode extends to about 15% of the emitter length only, and the

Effect of oxygen incorporation on the structure and elasticity of Ti-Al-O-N coatings synthesized by cathodic arc and high power pulsed magnetron sputtering

Energy Technology Data Exchange (ETDEWEB)

Hans, M., E-mail: hans@mch.rwth-aachen.de; Baben, M. to; Music, D.; Ebenhöch, J.; Schneider, J. M. [Materials Chemistry, RWTH Aachen University, Kopernikusstr. 10, D-52074 Aachen (Germany); Primetzhofer, D. [Department of Physics and Astronomy, Uppsala University, Lägerhyddsvägen 1, S-75120 Uppsala (Sweden); Kurapov, D.; Arndt, M.; Rudigier, H. [Oerlikon Balzers Coating AG, Iramali 18, LI-9496 Balzers, Principality of Liechtenstein (Liechtenstein)

2014-09-07

Ti-Al-O-N coatings were synthesized by cathodic arc and high power pulsed magnetron sputtering. The chemical composition of the coatings was determined by means of elastic recoil detection analysis and energy dispersive X-ray spectroscopy. The effect of oxygen incorporation on the stress-free lattice parameters and Young's moduli of Ti-Al-O-N coatings was investigated by X-ray diffraction and nanoindentation, respectively. As nitrogen is substituted by oxygen, implications for the charge balance may be expected. A reduction in equilibrium volume with increasing O concentration is identified by X-ray diffraction and density functional theory calculations of Ti-Al-O-N supercells reveal the concomitant formation of metal vacancies. Hence, the oxygen incorporation-induced formation of metal vacancies enables charge balancing. Furthermore, nanoindentation experiments reveal a decrease in elastic modulus with increasing O concentration. Based on ab initio data, two causes can be identified for this: First, the metal vacancy-induced reduction in elasticity; and second, the formation of, compared to the corresponding metal nitride bonds, relatively weak Ti-O and Al-O bonds.

Effect of oxygen incorporation on the structure and elasticity of Ti-Al-O-N coatings synthesized by cathodic arc and high power pulsed magnetron sputtering

International Nuclear Information System (INIS)

Hans, M.; Baben, M. to; Music, D.; Ebenhöch, J.; Schneider, J. M.; Primetzhofer, D.; Kurapov, D.; Arndt, M.; Rudigier, H.

2014-01-01

Ti-Al-O-N coatings were synthesized by cathodic arc and high power pulsed magnetron sputtering. The chemical composition of the coatings was determined by means of elastic recoil detection analysis and energy dispersive X-ray spectroscopy. The effect of oxygen incorporation on the stress-free lattice parameters and Young's moduli of Ti-Al-O-N coatings was investigated by X-ray diffraction and nanoindentation, respectively. As nitrogen is substituted by oxygen, implications for the charge balance may be expected. A reduction in equilibrium volume with increasing O concentration is identified by X-ray diffraction and density functional theory calculations of Ti-Al-O-N supercells reveal the concomitant formation of metal vacancies. Hence, the oxygen incorporation-induced formation of metal vacancies enables charge balancing. Furthermore, nanoindentation experiments reveal a decrease in elastic modulus with increasing O concentration. Based on ab initio data, two causes can be identified for this: First, the metal vacancy-induced reduction in elasticity; and second, the formation of, compared to the corresponding metal nitride bonds, relatively weak Ti-O and Al-O bonds

Intense pulsed heavy ion beam technology

International Nuclear Information System (INIS)

Masugata, Katsumi; Ito, Hiroaki

2010-01-01

Development of intense pulsed heavy ion beam accelerator technology is described for the application of materials processing. Gas puff plasma gun and vacuum arc discharge plasma gun were developed as an active ion source for magnetically insulated pulsed ion diode. Source plasma of nitrogen and aluminum were successfully produced with the gas puff plasma gun and the vacuum arc plasma gun, respectively. The ion diode was successfully operated with gas puff plasma gun at diode voltage 190 kV, diode current 2.2 kA and nitrogen ion beam of ion current density 27 A/cm 2 was obtained. The ion composition was evaluated by a Thomson parabola spectrometer and the purity of the nitrogen ion beam was estimated to be 86%. The diode also operated with aluminum ion source of vacuum arc plasma gun. The ion diode was operated at 200 kV, 12 kA, and aluminum ion beam of current density 230 A/cm 2 was obtained. The beam consists of aluminum ions (Al (1-3)+ ) of energy 60-400 keV, and protons (90-130 keV), and the purity was estimated to be 89%. The development of the bipolar pulse accelerator (BPA) was reported. A double coaxial type bipolar pulse generator was developed as the power supply of the BPA. The generator was tested with dummy load of 7.5 ohm, bipolar pulses of -138 kV, 72 ns (1st pulse) and +130 kV, 70 ns (2nd pulse) were successively generated. By applying the bipolar pulse to the drift tube of the BPA, nitrogen ion beam of 2 A/cm 2 was observed in the cathode, which suggests the bipolar pulse acceleration. (author)

Compact Rare Earth Emitter Hollow Cathode

Science.gov (United States)

Watkins, Ronald; Goebel, Dan; Hofer, Richard

2010-01-01

A compact, high-current, hollow cathode utilizing a lanthanum hexaboride (LaB6) thermionic electron emitter has been developed for use with high-power Hall thrusters and ion thrusters. LaB6 cathodes are being investigated due to their long life, high current capabilities, and less stringent xenon purity and handling requirements compared to conventional barium oxide (BaO) dispenser cathodes. The new cathode features a much smaller diameter than previously developed versions that permit it to be mounted on axis of a Hall thruster ( internally mounted ), as opposed to the conventional side-mount position external to the outer magnetic circuit ("externally mounted"). The cathode has also been reconfigured to be capable of surviving vibrational loads during launch and is designed to solve the significant heater and materials compatibility problems associated with the use of this emitter material. This has been accomplished in a compact design with the capability of high-emission current (10 to 60 A). The compact, high-current design has a keeper diameter that allows the cathode to be mounted on the centerline of a 6- kW Hall thruster, inside the iron core of the inner electromagnetic coil. Although designed for electric propulsion thrusters in spacecraft station- keeping, orbit transfer, and interplanetary applications, the LaB6 cathodes are applicable to the plasma processing industry in applications such as optical coatings and semiconductor processing where reactive gases are used. Where current electrical propulsion thrusters with BaO emitters have limited life and need extremely clean propellant feed systems at a significant cost, these LaB6 cathodes can run on the crudest-grade xenon propellant available without impact. Moreover, in a laboratory environment, LaB6 cathodes reduce testing costs because they do not require extended conditioning periods under hard vacuum. Alternative rare earth emitters, such as cerium hexaboride (CeB6) can be used in this

IKOR - An isochronous pulse compressor ring for proton beams

International Nuclear Information System (INIS)

Schaffer, G.

1981-06-01

This report contains the results of a study carried out for an isochronous compressor ring IKOR which compresses the 500 μs linac macropulses into pulses of 0.68 μs length. Its basic component is a ring magnet with alternating gradient and separated functions. Due to the isochronous operation, an rf system can be avoided which otherwise would be necessary in order to maintain a void in the circulating beam for the purpose of ejection. Injection is performed by charge exchange. The H - beam of the accelerator is first converted into a H 0 beam by stripping off one electron by a high gradient magnet placed in the transfer channel. Subsequently, the beam is converted into a proton beam by removing the remaining electron through a stripping foil in the ring. IKOR will be filled in 658 turns. Immediately after filling, the beam is ejected in a single turn via a kicker and a septum magnet and is transported to the spallation target. Because of the high intensity of 2.7 x 10 14 protons per pulse and, secondly, due to the high repetition rate of 100 Hz, beam dynamics and radiation protection aspects dominate the design and are, for this reason, treated in detail. (orig.)

Nanotube cathodes.

Energy Technology Data Exchange (ETDEWEB)

Overmyer, Donald L.; Lockner, Thomas Ramsbeck; Siegal, Michael P.; Miller, Paul Albert

2006-11-01

Carbon nanotubes have shown promise for applications in many diverse areas of technology. In this report we describe our efforts to develop high-current cathodes from a variety of nanotubes deposited under a variety of conditions. Our goal was to develop a one-inch-diameter cathode capable of emitting 10 amperes of electron current for one second with an applied potential of 50 kV. This combination of current and pulse duration significantly exceeds previously reported nanotube-cathode performance. This project was planned for two years duration. In the first year, we tested the electron-emission characteristics of nanotube arrays fabricated under a variety of conditions. In the second year, we planned to select the best processing conditions, to fabricate larger cathode samples, and to test them on a high-power relativistic electron beam generator. In the first year, much effort was made to control nanotube arrays in terms of nanotube diameter and average spacing apart. When the project began, we believed that nanotubes approximately 10 nm in diameter would yield sufficient electron emission properties, based on the work of others in the field. Therefore, much of our focus was placed on measured field emission from such nanotubes grown on a variety of metallized surfaces and with varying average spacing between individual nanotubes. We easily reproduced the field emission properties typically measured by others from multi-wall carbon nanotube arrays. Interestingly, we did this without having the helpful vertical alignment to enhance emission; our nanotubes were randomly oriented. The good emission was most likely possible due to the improved crystallinity, and therefore, electrical conductivity, of our nanotubes compared to those in the literature. However, toward the end of the project, we learned that while these 10-nm-diameter CNTs had superior crystalline structure to the work of others studying field emission from multi-wall CNT arrays, these nanotubes still

Nanotube cathodes

International Nuclear Information System (INIS)

Overmyer, Donald L.; Lockner, Thomas Ramsbeck; Siegal, Michael P.; Miller, Paul Albert

2006-01-01

Carbon nanotubes have shown promise for applications in many diverse areas of technology. In this report we describe our efforts to develop high-current cathodes from a variety of nanotubes deposited under a variety of conditions. Our goal was to develop a one-inch-diameter cathode capable of emitting 10 amperes of electron current for one second with an applied potential of 50 kV. This combination of current and pulse duration significantly exceeds previously reported nanotube-cathode performance. This project was planned for two years duration. In the first year, we tested the electron-emission characteristics of nanotube arrays fabricated under a variety of conditions. In the second year, we planned to select the best processing conditions, to fabricate larger cathode samples, and to test them on a high-power relativistic electron beam generator. In the first year, much effort was made to control nanotube arrays in terms of nanotube diameter and average spacing apart. When the project began, we believed that nanotubes approximately 10 nm in diameter would yield sufficient electron emission properties, based on the work of others in the field. Therefore, much of our focus was placed on measured field emission from such nanotubes grown on a variety of metallized surfaces and with varying average spacing between individual nanotubes. We easily reproduced the field emission properties typically measured by others from multi-wall carbon nanotube arrays. Interestingly, we did this without having the helpful vertical alignment to enhance emission; our nanotubes were randomly oriented. The good emission was most likely possible due to the improved crystallinity, and therefore, electrical conductivity, of our nanotubes compared to those in the literature. However, toward the end of the project, we learned that while these 10-nm-diameter CNTs had superior crystalline structure to the work of others studying field emission from multi-wall CNT arrays, these nanotubes still

Preparation of Gd2O3 Ultrafine Nanoparticles by Pulse Electrodeposition Followed by Heat-treatment Method

Directory of Open Access Journals (Sweden)

Mustafa Aghazadeh

2016-12-01

Full Text Available Gd2O3 nanoparticles were prepared by a two–step process; cathodic electrodeposition followed by heat-treatment method. First, Gd(OH3 nanoparticles was galvanostatically deposited from nitrate bath on the steel substrate by pulse current (PC mode. The deposition experiments was conducted at a typical on-time and off-time (ton=1ms and toff=1ms for 60 min. The electrodeposited precursor was then heat-treated at 600 oC for 3h to obtain oxide product (i.e. Gd2O3. The morphological and structural analyses confirmed that the gadolinium hydroxynitrate nanoparticles with composition of [Gd(OH2.5(NO30.5 yH2O] and uniform size about 10 nm have been prepared during pulse cathodic electrodeposition process. Furthermore, mechanism of the gadolinium hydroxynitrate nanoparticles was explained based on the base (OH– electrogeneration process on the cathode surface. The morphological observations by SEM and TEM, and structural analyses via XRD and FT-IR revealed that the oxide product is composed of well-dispersed Gd2O3 nanoparticles with pure cubic crystalline structure. It was observed that the calcination process has no effect on the morphology of the Gd2O3 nanoparticles. Mechanism of oxide formation during heat-treatment step was investigated by DSC-TG analysis and discussed in detail. The results of this work showed that pulse current deposition followed by heat–treatment can be recognized as an easy and facile method for preparation of the Gd2O3 fine nanoparticles.

Intense Non-Linear Soft X-Ray Emission from a Hydride Target during Pulsed D Bombardment

Science.gov (United States)

Miley, George H.; Yang, Yang; Lipson, Andrei; Haque, Munima; Percel, Ian; Romer, Michael

Radiation emission from low-energy nuclear radiation (LENR) electrodes (both charged-particle and X-rays) represents an important feature of LENR in general. Here, calibration, measurement techniques, and soft X-ray emission results from deuterium bombardment of a Pd target (cathode) placed in a pulsed deuterium glow discharge (PGD) are described. An X-ray intensity of 13.4 mW/cm2 and a dose of 3.3 μJ/cm2 were calculated over a 0.5 ms pulse time from AXUV photodiode radiation detector measurements. A most striking feature is that X-ray energies >600 V are observed with a discharge voltage only about half of that value. To further investigate this phenomenon, emission during room temperature D-desorption from electrolytically loaded Pd:Dx cathodes was also studied. The X-ray emission energy observed was quite similar to the PGD case. However, the intensity in this case was almost 13 orders of magnitude lower due to the much lower deuterium fluxes involved.

Intense non-linear soft X-ray emission from a hydride target during pulsed D bombardment

International Nuclear Information System (INIS)

Miley, George H.; Yang, Yang; Lipson, Andrei; Haque, Munima; Percel, Ian; Romer, Michael

2006-01-01

Radiation emission from low-energy nuclear radiation (LENR) electrodes (both charged-particle and X-rays) represents an important feature of LENR in general. Here, calibration, measurement techniques, and soft X-ray emission results from deuterium bombardment of a Pd target (cathode) placed in a pulsed deuterium glow discharge (PGD) are described. An X-ray intensity of 13.4 mW/cm 2 and a dose of 3.3 μJ/cm 2 were calculated over a 0.5 ms pulse time from AXUV photodiode radiation detector measurements. A most striking feature is that X-ray energies >600 V are observed with a discharge voltage only about half of that value. To further investigate this phenomenon, emission during room temperature D-desorption from electrolytically loaded Pd:Dx cathodes was also studied. The X-ray emission energy observed was quite similar to the PGD case. However, the intensity in this case was almost 13 orders of magnitude lower due to the much lower deuterium fluxes involved. (author)

Anodic stripping voltammetry of mercury, zinc, cadmium, and lead in a rice farm ecosystem

International Nuclear Information System (INIS)

Del Mundo, F.R.; Vicente-Beckett, V.A.

1990-01-01

Analytical procedures based on differential pulse anodic stripping voltammetry were developed and applied to the analysis of some trace metals in a rice farm ecosystem. A gold wire served as working electrode for the analysis of mercury in 0.1M HNO 3 ; a hanging mercury drop electrode was used for the simultaneous analyses of zinc, cadmium, and lead in 0.1M sodium acetate buffer (pH 4.5). Mercury was pre-concentrated for five minutes at + 0.20 V vs SCE. The area of the anodic stripping peaks varied linearly over the concentration range 3x10 -10 -2x10 -8 M Hg(II); the limit of detection was 0.06 ppb or 3x10 -10 M Hg(II). The simultaneous analytical method involved pre-electrolysis at -1.2 V vs SCE for ten minutes. The heights of the individual anodic stripping peaks varied linearly with concentration in a mixture of the ions over the concentration range 0.020-0.10 ppm for each ion; the limits of detection were 0.004 ppm, 0.01 ppm, and 0.01 ppm for Cd, Pb, Zn, respectively. The developed procedures were used to determine the baseline levels of these metals in soil, water, and rice plant samples from a one-hectare traditional rice farm in San Pedro, Laguna. (auth.). 26 refs.; 4 tabs.; 6 figs

TRACE ANALYSIS BY LASER-EXCITED ATOMIC FLUORESCENCE WITH ATOMIZATION IN A PULSED PLASMA

OpenAIRE

Lunyov , O.; Oshemkov , S.; Petrov , A.

1991-01-01

The possibilities of plasma atomization for laser fluorescence trace analysis are discussed. Pulsed hot hollow cathode discharge was used for analysis of solutions and powdered samples. The high voltage spark and laser-induced breakdown (laser spark) were used as atomizers of metal-containing atmospheric aerosols. Detection limits were improved by means of temporal background selection.

Cathode Effects in Cylindrical Hall Thrusters

Energy Technology Data Exchange (ETDEWEB)

Granstedt, E.M.; Raitses, Y.; Fisch, N. J.

2008-09-12

Stable operation of a cylindrical Hall thruster (CHT) has been achieved using a hot wire cathode, which functions as a controllable electron emission source. It is shown that as the electron emission from the cathode increases with wire heating, the discharge current increases, the plasma plume angle reduces, and the ion energy distribution function shifts toward higher energies. The observed effect of cathode electron emission on thruster parameters extends and clarifies performance improvements previously obtained for the overrun discharge current regime of the same type of thruster, but using a hollow cathode-neutralizer. Once thruster discharge current saturates with wire heating, further filament heating does not affect other discharge parameters. The saturated values of thruster discharge parameters can be further enhanced by optimal placement of the cathode wire with respect to the magnetic field.

Clipper circuit of pulse modulator used for klystron-5045 power supply

CERN Document Server

Akimov, A V

2001-01-01

While the operation of modulator to the pulsed transformer of klystron-5045, current through the primary winding of the pulse transformer (PT) continues to flow even upon the end of the klystron voltage operating pulse. This is determined by an energy stored in magnetizing inductance. The prolongation of magnetizing current passing process simultaneously with the premature choking of thyratron can cause high voltage of inverse polarity at the klystron, which cause the destruction of the cathode. We have considered the possibility of shortening time of magnetizing current passage for the charge of reasonable choice of clipper circuit parameters. The behavior of clipper circuit was studied in modulators used for the VEPP-5 (BINP, Russia) preinjector klystron power supply. The optimum operation run of the circuit was selected and its design features are described.

A one-dimensional model illustrating virtual-cathode formation in a novel coaxial virtual-cathode oscillator

International Nuclear Information System (INIS)

Turner, Geoffrey R.

2014-01-01

A one-dimensional electrostatic sheet model of a coaxial geometry Virtual Cathode Oscillator (VCO) is presented. The cathode is centrally located and connects to a peripherally located plate electrode to form a resonant cavity, and is thus considered to be a novel design. Charge is modelled as concentric sheets about the cathode whose absolute position and velocity are determined as a function of time by solving the relativistic equations of motion. The model predicts the formation of a virtual cathode between the grid and plate electrodes for the case of a space-charge limited current. Setting the electron reflexing frequency (as a function of the grid potential) comparable with the cavity resonant frequency is predicted to improve the efficiency of microwave emission

A Novel Cathode Material for Cathodic Dehalogenation of 1,1-Dibromo Cyclopropane Derivatives.

Science.gov (United States)

Gütz, Christoph; Selt, Maximilian; Bänziger, Markus; Bucher, Christoph; Römelt, Christina; Hecken, Nadine; Gallou, Fabrice; Galvão, Tomás R; Waldvogel, Siegfried R

2015-09-28

Leaded bronze turned out to be an excellent cathode material for the dehalogenation reaction of cyclopropanes without affecting the strained molecular entity. With this particular alloy, beneficial properties of lead cathodes are conserved, whereas the corrosion of cathode is efficiently suppressed. The solvent in the electrolyte determines whether a complete debromination reaction is achieved or if the process can be selectively stopped at the monobromo cyclopropane intermediate. The electroorganic conversion tolerates a variety of functional groups and can be conducted at rather complex substrates like cyclosporine A. This approach allows the sustainable preparation of cyclopropane derivatives. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Superconducting nano-strip particle detectors

International Nuclear Information System (INIS)

Cristiano, R; Ejrnaes, M; Casaburi, A; Zen, N; Ohkubo, M

2015-01-01

We review progress in the development and applications of superconducting nano-strip particle detectors. Particle detectors based on superconducting nano-strips stem from the parent devices developed for single photon detection (SSPD) and share with them ultra-fast response times (sub-nanosecond) and the ability to operate at a relatively high temperature (2–5 K) compared with other cryogenic detectors. SSPDs have been used in the detection of electrons, neutral and charged ions, and biological macromolecules; nevertheless, the development of superconducting nano-strip particle detectors has mainly been driven by their use in time-of-flight mass spectrometers (TOF-MSs) where the goal of 100% efficiency at large mass values can be achieved. Special emphasis will be given to this case, reporting on the great progress which has been achieved and which permits us to overcome the limitations of existing mass spectrometers represented by low detection efficiency at large masses and charge/mass ambiguity. Furthermore, such progress could represent a breakthrough in the field. In this review article we will introduce the device concept and detection principle, stressing the peculiarities of the nano-strip particle detector as well as its similarities with photon detectors. The development of parallel strip configuration is introduced and extensively discussed, since it has contributed to the significant progress of TOF-MS applications. (paper)

Nanosecond radar system based on repetitive pulsed relativistic BWO

International Nuclear Information System (INIS)

Bunkin, B.V.; Gaponov-Grekhov, A.V.; Eltchaninov, A.S.; Zagulov, F.Ya.; Korovin, S.D.; Mesyats, G.A.; Osipov, M.L.; Otlivantchik, E.A.; Petelin, M.I.; Prokhorov, A.M.

1993-01-01

The paper presents the results of studies of a nanosecond radar system based on repetitive pulsed relativistic BWO. A pulsed power repetitive accelerator producing electron beams of electron energy 500-700 keV and current 5 kA in pulses of duraction 10 ns with a repetition rate of 100 pps is described. The results of experiments with a high-voltage gas-filled spark gap and a cold-cathode vacuum diode under the conditions of high repetition rates are given. Also presented are the results of studies of a relativistic BWO operating with a wavelength of 3 cm. It is shown that for a high-current beam electron energy of 500-700 keV, the BWO efficiency can reach 35%, the microwave power being 10 9 W. A superconducting solenoid creating a magnetic field of 30 kOe was used for the formation and transportation of the high-current electron beam. In conclusion, the outcome of tests of a nanosecond radar station based on a pulsed power repetitive accelerator and a relativistic BWO is reported

Phase control of Mn-based spinel films via pulsed laser deposition

International Nuclear Information System (INIS)

Feng, Zhenxing; Chen, Xiao; Fister, Timothy T.; Bedzyk, Michael J.; Fenter, Paul

2016-01-01

Phase transformations in battery cathode materials during electrochemical-insertion reactions lead to capacity fading and low cycle life. One solution is to keep the same phase of cathode materials during cation insertion-extraction processes. Here, we demonstrate a novel strategy to control the phase and composition of Mn-based spinel oxides for magnesium-ion battery applications through the growth of thin films on lattice-matched substrates using pulsed laser deposition. Materials at two extreme conditions are considered: fully discharged cathode MgMn_2O_4 and fully charged cathode Mn_2O_4. The tetragonal MgMn_2O_4 (MMO) phase is obtained on MgAl_2O_4 substrates, while the cubic MMO phase is obtained on MgO substrates. Similarly, growth of the empty Mn_2O_4 spinel in the cubic phase is obtained on an MgO substrate. These results demonstrate the ability to control separately the phase of spinel thin films (e.g., tetragonal vs. cubic MMO) at nominally fixed composition, and to maintain a fixed (cubic) phase while varying its composition (MgxMn_2O_4, for x = 0, 1). As a result, this capability provides a novel route to gain insights into the operation of battery electrodes for energy storage applications.

Reflective article having a sacrificial cathodic layer

Science.gov (United States)

Kabagambe, Benjamin; Buchanan, Michael J.; Scott, Matthew S.; Rearick, Brian K.; Medwick, Paul A.; McCamy, James W.

2017-09-12

The present invention relates to reflective articles, such as solar mirrors, that include a sacrificial cathodic layer. The reflective article, more particularly includes a substrate, such as glass, having a multi-layered coating thereon that includes a lead-free sacrificial cathodic layer. The sacrificial cathodic layer includes at least one transition metal, such as a particulate transition metal, which can be in the form of flakes (e.g., zinc flakes). The sacrificial cathodic layer can include an inorganic matrix formed from one or more organo-titanates. Alternatively, the sacrificial cathodic layer can include an organic polymer matrix (e.g., a crosslinked organic polymer matrix formed from an organic polymer and an aminoplast crosslinking agent). The reflective article also includes an outer organic polymer coating, that can be electrodeposited over the sacrificial cathodic layer.

Geiger counters of gamma rays with a bismuth cathode; Compteurs de geiger a rayons gamma a cathode de bismuth

Energy Technology Data Exchange (ETDEWEB)

Meunier, R; Legrand, J P [Commissariat a l' Energie Atomique, Saclay(France). Centre d' Etudes Nucleaires

1953-07-01

Geiger Muller counters present a lake of efficiency of some per cent, for the {gamma} radiations. In the region 0,3 - 1 MeV, a substantial growth of their output can be obtained by a special construction of their cathode. In accordance with previous works, we constructed some counter of formed cathode by a pleated copper wire fencing covered of Bi by electrolysis. The successive modifications brought to a cylindrical conventional cathode in sheet metal of copper, that succeeds to this type of cathode, drive to an improvement of the output. (M.B.) [French] Les compteurs de Geiger Muller presentent une efficacite assez faible de l'ordre de quelques pour cent, pour les rayonnements {gamma}. Dans la region 0,3 - 1 MeV, un accroissement substantiel de leur rendement peut etre obtenu par une construction speciale de leur cathode. Conformement a des travaux anterieurs, nous avons construit des compteurs a cathode formee par un grillage de cuivre plisse recouvert de Bi par electrolyse. Les modifications successives apportees a une cathode conventionnelle cylindrique en tole de cuivre, qui aboutissent a ce type de cathode, conduisent a une amelioration du rendement. (M.B.)

Depletive stripping chronopotentiometry : a major step forward in electrochemical stripping techniques for metal ion speciation analysis

NARCIS (Netherlands)

Town, R.M.; Leeuwen, van H.P.

2004-01-01

A comparative evaluation of the utility of the various modes of stripping chronopotentiometry (SCP) for trace metal speciation analysis is presented in the broad context of stripping voltammetric techniques. The remarkable fundamental advantages of depletive SCP at scanned deposition potential

A high-gradient high-duty-factor Rf photo-cathode electron gun

International Nuclear Information System (INIS)

Rimmer, Robert A.; Hartman, Neal; Lidia, Steven M.; Wang, Shaoheng

2002-01-01

We describe the analysis and preliminary design of a high-gradient, high-duty factor RF photocathode gun. The gun is designed to operate at high repetition rate or CW, with high gradient on the cathode surface to minimize emittance growth due to space charge forces at high bunch charge. The gun may also be operated in a solenoidal magnetic field for emittance compensation. The design is intended for use in short-pulse, high-charge, and high-repetition rate applications such as linac based X-ray sources. We present and compare the results of gun simulations using different codes, as well as RF and thermal analysis of the structure

A high-gradient high-duty-factor RF photo-cathode electron gun

International Nuclear Information System (INIS)

Rimmer, Robert; Hartman, N.; Lidia, S.; Wang, S.H.

2002-01-01

We describe the analysis and preliminary design of a high-gradient, high-duty factor RF photocathode gun. The gun is designed to operate at high repetition rate or CW, with high gradient on the cathode surface to minimize emittance growth due to space charge forces at high bunch charge. The gun may also be operated in a solenoidal magnetic field for emittance compensation. The design is intended for use in short-pulse, high-charge, and high-repetition rate applications such as linac based X-ray sources. We present and compare the results of gun simulations using different codes, as well as RF and thermal analysis of the structure

Heat treatment of cathodic arc deposited amorphous hard carbon films

Energy Technology Data Exchange (ETDEWEB)

Anders, S.; Ager, J.W. III; Brown, I.G. [and others

1997-02-01

Amorphous hard carbon films of varying sp{sup 2}/sp{sup 3} fractions have been deposited on Si using filtered cathodic are deposition with pulsed biasing. The films were heat treated in air up to 550 C. Raman investigation and nanoindentation were performed to study the modification of the films caused by the heat treatment. It was found that films containing a high sp{sup 3} fraction sustain their hardness for temperatures at least up to 400 C, their structure for temperatures up to 500 C, and show a low thickness loss during heat treatment. Films containing at low sp{sup 3} fraction graphitize during the heat treatment, show changes in structure and hardness, and a considerable thickness loss.

An experimental study of molten salt electrorefining of uranium using solid iron cathode and liquid cadmium cathode for development of pyrometallurgical reprocessing

International Nuclear Information System (INIS)

Koyama, Tadafumi; Iizuka, Masatoshi; Tanaka, Hiroshi; Tokiwai, Moriyasu; Shoji, Yuichi; Fujita, Reiko; Kobayashi, Tsuguyuki.

1997-01-01

Electrorefining of uranium was studied for developing pyrometallurgical reprocessing technology of metal fuel cycle. After concentration dependence of polarization curve was measured, uranium was electrodeposited either on solid iron cathode or in liquid cadmium cathode. Design and operational conditions of the cathode were improved for obtaining much greater quantity of deposit, resulting in recovery of 732g of dendritic uranium on a single solid cathode, and of 232g of uranium in 2,344g of a liquid cadmium cathode. The behaviors of electro-codeposition of rare earth elements with uranium were observed for liquid cadmium cathode, and were found to follow the local equilibrium between salt electrolyte and cathode. The decontamination factors of FP simulating elements from uranium were tentatively determined as >2,000 for deposition to solid cathode and as >7 for deposition to liquid cadmium cathode, respectively. (author)

Ductility of reinforced concrete columns confined with stapled strips

International Nuclear Information System (INIS)

Tahir, M.F.; Khan, Q.U.Z.; Shabbir, F.; Sharif, M.B.; Ijaz, N.

2015-01-01

Response of three 150x150x450mm short reinforced concrete (RC) columns confined with different types of confining steel was investigated. Standard stirrups, strips and stapled strips, each having same cross-sectional area, were employed as confining steel around four comer column bars. Experimental work was aimed at probing into the affect of stapled strip confinement on post elastic behavior and ductility level under cyclic axial load. Ductility ratios, strength enhancement factor and core concrete strengths were compared to study the affect of confinement. Results indicate that strength enhancement in RC columns due to strip and stapled strip confinement was not remarkable as compared to stirrup confined column. It was found that as compared to stirrup confined column, stapled strip confinement enhanced the ductility of RC column by 183% and observed axial capacity of stapled strip confined columns was 41 % higher than the strip confined columns. (author)

Potential profile in a conducting polymer strip

DEFF Research Database (Denmark)

Bay, Lasse; West, Keld; Vlachopoulos, Nikolaos

2002-01-01