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1

Study of Atmospheric Pressure Abnormal Glow Discharge  

NASA Astrophysics Data System (ADS)

Atmospheric pressure abnormal glow discharge (APAGD) was carried out simply with a transformer of 1: 500 driven by a alternating current with a frequency of 50 Hz. Typical stable discharge parameters, namely voltage of 400 V to 850 V and current of 60 mA to 110 mA were measured by oscillograph. Simulation of the discharge process suggested that the stable discharge was supported by the impedance from the secondary coil of the transformer, which offered a negative feedback to prevent the discharge from turning into an arc. An interpretation was given for the oscillogram of the sinuous discharge current and square voltage. Furthermore, the electron temperature and electron density averaged in the discharge channel of APAGD were estimated.

Li, Xiang; Tang, Changjian; Dai, Xiaoyan; Yin, Yongxiang

2008-04-01

2

Study Of Titanium Emission Spectra In N2 - H2 Abnormal DC Glow Discharge  

NASA Astrophysics Data System (ADS)

In this paper we tried to answer why small amount of hydrogen (3 %) in a nitrogen abnormal glow discharge so strongly reduce Ti I spectral line intensities. Decreasing of Ti I line intensities in N2 - H2 discharge are compared with less pronounced decreasing of N I line intensities. Using emission spectroscopy we have observed that line intensity changes are correlated to variations in electron energy distribution function (EEDF) and change of metastable density.

Obradovic, B. M.; Cvetanovic, N.; Kuraica, M. M.

2010-07-01

3

Excessive Balmer line broadening in a plane cathode abnormal glow discharge in hydrogen  

SciTech Connect

Results of a Doppler spectroscopy study of the hydrogen Balmer alpha line in an abnormal glow discharge operated in pure hydrogen are reported. Measurements of line shapes are performed side-on to the discharge axis in a low electric field region of negative glow. The excessive Balmer alpha broadening is detected and its presence and linewidth is related to the collisions of fast hydrogen atoms with molecular hydrogen. The collision model enabled also an estimation of effective cross section data from the Balmer alpha axial intensity decay curves. Large excessive Balmer alpha line broadening in pure hydrogen and its dependence upon the direction of observation with respect to the electric field is in contradiction to the resonance transfer model, proposed byMills et al. in several publications [see, e.g., IEEE Trans. Plasma Sci. 31, 338 (2003)].

Cvetanovic, N.; Kuraica, M.M.; Konjevic, N. [Center for Science and Development of Technology, Obilicev Venac 26, Belgrade, and Faculty of Transport and Traffic Engineering, University of Belgrade, V. Stepe 305, Belgrade (Serbia and Montenegro); Faculty of Physics, University of Belgrade, P.O. Box 368, 11001 Belgrade, and Center for Science and Development of Technology, Obilicev Venac 26, Belgrade (Serbia and Montenegro); Faculty of Physics, University of Belgrade, P.O. Box 368, 11001 Belgrade (Serbia and Montenegro)

2005-02-01

4

Simulation of transition from Townsend mode to glow discharge mode in a helium dielectric barrier discharge at atmospheric pressure  

NASA Astrophysics Data System (ADS)

The dielectric barrier discharge characteristics in helium at atmospheric pressure are simulated based on a one-dimensional fluid model. Under some discharge conditions, the results show that one discharge pulse per half voltage cycle usually appears when the amplitude of external voltage is low, while a glow-like discharge occurs at high voltage. For the one discharge pulse per half voltage cycle, the maximum of electron density appears near the anode at the beginning of the discharge, which corresponds to a Townsend discharge mode. The maxima of the electron density and the intensity of electric field appear in the vicinity of the cathode when the discharge current increases to some extent, which indicates the formation of a cathode-fall region. Therefore, the discharge has a transition from the Townsend mode to the glow discharge mode during one discharge pulse, which is consistent with previous experimental results.

Li, Xue-Chen; Niu, Dong-Ying; Xu, Long-Fei; Jia, Peng-Ying; Chang, Yuan-Yuan

2012-07-01

5

CF4 decompositions using streamer- and glow-mode in dielectric barrier discharges  

Microsoft Academic Search

A Dielectric barrier discharge (DBD) is a promising candidate to remove carbon tetrafluoride (CF4) because the DBD has been successfully used for generating ozone (O3) and decomposing nitrogen oxide (NO). A streamer- and glow-mode operations of DBD were carried out in a coaxial cylinder reactor by coupling 10-kHz alternate current (ac) power. The effect of oxygen on the CF4 decompositions

Yongho Kim; Kwan-Tae Kim; Min Suk Cha; Young-Hoon Song; Seock Joon Kim

2005-01-01

6

An abnormal mode of torsion pendulum and its suppression  

NASA Astrophysics Data System (ADS)

The numerical solution of non-linear equations shows that the abnormal mode observed in our torsion pendulum experiments is an intrinsic mode of the pendulum. Further analysis shows that the amplitude of abnormal mode increasing with of swing modes can be suppressed with a magnetic damper effectively.

Tu, Ying; Zhao, Liang; Liu, Qi; Ye, Hong-Ling; Luo, Jun

2004-11-01

7

Study of nonlinear oscillations in a glow discharge plasma using empirical mode decomposition and Hilbert Huang transform  

NASA Astrophysics Data System (ADS)

Hilbert Huang transform (HHT) based time series analysis was carried out on nonlinear floating potential fluctuations obtained from hollow cathode glow discharge plasma in the presence of anode glow. HHT was used to obtain contour plots and the presence of nonlinearity was studied. Frequency shift with time, which is a typical nonlinear behaviour, was detected from the contour plots. Various plasma parameters were measured and the concepts of correlation coefficients and the physical contribution of each intrinsic mode function have been discussed. Physically important quantities such as instantaneous energy and their uses in studying physical phenomena such as intermittency and non-stationary data have also been discussed.

Wharton, A. M.; Sekar Iyengar, A. N.; Janaki, M. S.

2013-02-01

8

Default Mode Network Abnormalities in Bipolar Disorder and Schizophrenia  

PubMed Central

The default-mode network (DMN) consists of a set of brain areas preferentially activated during internally focused tasks. We used functional MRI to study the DMN in bipolar mania and acute schizophrenia. 17 bipolar disorder (BD), 14 schizophrenia (SZ) and 15 normal control (NC) subjects underwent 10-minute resting scans. The DMN was extracted using independent component analysis and template-matching; spatial extent and timecourse were examined. Both patient groups showed reduced DMN connectivity in the medial prefrontal cortex (mPFC) (BD:x=-2,y=54,z=-12; SZ:x=-2,y=22,z=18). BD subjects showed abnormal recruitment of parietal cortex (correlated with mania severity) while SZ subjects showed greater recruitment of the frontopolar cortex/basal ganglia. Both groups had significantly higher frequency fluctuations than controls (frequency × diagnosis:F(43,2)=3.183,p=0.05). We found ventral mPFC abnormalities in BD and dorsal mPFC abnormalities in SZ. The higher frequency of BOLD signal oscillations observed in patients suggests abnormal functional organization of circuits in both disorders. Further studies are needed to determine how these abnormalities are related to specific symptoms of each condition.

Ongur, Dost; Lundy, Miriam; Greenhouse, Ian; Shinn, Ann K.; Menon, Vinod; Cohen, Bruce M.; Renshaw, Perry F.

2010-01-01

9

Organic chemistry of NH3 and HCN induced by an atmospheric abnormal glow discharge in N2-CH4 mixtures  

NASA Astrophysics Data System (ADS)

The formation of the chemical products produced in an atmospheric glow discharge fed by a N2-CH4 gas mixture has been studied using Fourier Transform InfraRed (FTIR) and Optical Emission Spectrometry (OES). The measurements were carried out in a flowing regime at ambient temperature and pressure with CH4 concentrations ranging from 0.5% to 2%. In the recorded emission spectra the lines of the second positive system CN system and the first negative system of N2 were found to be the most intensive but atomic H?, H?, and C (247 nm) lines were also observed. FTIR-measurements revealed HCN and NH3 to be the major products of the plasma with traces of C2H2. These same molecules have been detected in Titan's atmosphere and the present experiments may provide some novel insights into the chemical and physical mechanisms prevalent in Titan's atmosphere with these smaller species believed to be the precursors of heavier organic species in Titan's atmosphere and on its surface.

Horvath, G.; Krcma, F.; Polachova, L.; Klohnova, K.; Mason, N. J.; Zahoran, M.; Matejcik, S.

2011-01-01

10

Glowing Pickle  

NSDL National Science Digital Library

In this activity, high voltage is applied across a pickle to emit a yellow glow. This activity should only be conducted by skilled adults and is best suited as a demonstration. Optional extensions to this activity include soaking the pickle for week in brine to emit a pink glow and using several pickles at once.

Doherty, Paul

2001-01-01

11

Transitions between Glow and Arc Modes and Its Influences to the Performance of a Hollow-Cathode Discharge CO2 Laser  

NASA Astrophysics Data System (ADS)

Hollow cathode discharge is used for excitation of a CO2 laser. With the aluminum alloy cathode a maximum laser output power of 4.1 W is obtained. This laser output power is related to the formation of aluminum oxide at the cathode surface. These oxide layers induce the transitions between the glow and arc modes of the discharge and formation of microarcs at the cathode surface. This was found beneficial for the laser operation. The results of the time resolved study of the laser parameters are also reported.

Ivkovi?, Milivoje; Konjevi?, Nikola

1995-10-01

12

Glowing Tonic  

NSDL National Science Digital Library

In this sunny day activity, learners compare how a cup of water and a cup of tonic water reflect or refract light in the sun. Learners will be surprised to observe the top of the tonic water "glowing" blue. This activity includes articles explaining the reflection and refraction of light.

America, Optical S.

2008-01-01

13

Surface modification of poly(epsilon-caprolactone) using a dielectric barrier discharge in atmospheric pressure glow discharge mode.  

PubMed

The role of roughening and functionalization processes involved in modifying the wettability of poly(epsilon-caprolactone) (PCL) after treatment by an atmospheric pressure glow discharge plasma is discussed. The change in the ratio of CO/C-O bonds is a significant factor influencing the wettability of PCL. As the contact angle decreases, the level of CO bonds tends to rise. Surface roughness alterations are the driving force for lasting increases in wettability, while the surface functional species are shorter lived. We can approximate from ageing that the increase in wettability for PCL after plasma treatment is 55-60% due to roughening and 40-45% due to surface functionalization for the plasma device investigated. PMID:19269907

Little, Uel; Buchanan, Fraser; Harkin-Jones, Eileen; Graham, Bill; Fox, Brendan; Boyd, Adrian; Meenan, Brian; Dickson, Glenn

2009-02-04

14

Thar She Glows!  

NSDL National Science Digital Library

Learners observe glow-in-the-dark objects in a homemade light-proof box. Objects can include glow sticks, glow-in-the-dark toys, and toys with fluorescent paint. The box is built with a black light installed, which can be controlled with a switch outside the box. Background information is provided about the difference between fluorescence (glows only when light is shined on it) and phosphorescence (continues to glow after light is removed), and an electron-level explanation is also provided.

Industry, Oregon M.

1997-01-01

15

The Sky-Glows  

Microsoft Academic Search

THE glowing sunsets having reappeared, though far less brilliant than in November and December last, I send you a list of the most remarkable of them which have been noticed at Clairvaux, in the Department of Aube. They appeared with the same features as have been so often described in NATURE, and were especially glowing on the following days:-November 25,

P. K

1884-01-01

16

Glow discharge detector  

DOEpatents

A highly sensitive electronic ion cell for the measurement of trace elements in He carrier gas which involves glow discharge. A constant wave (CW) glow discharge detector which is controlled through a biased resistor, can detect the change of electron density caused by impurities in the He carrier gas by many orders of magnitude larger than that caused by direct ionization or electron capture. The glow discharge detector utilizes a floating pseudo-electrode to form a probe in or near the plasma. By using this probe, the large variation of electron density due to trace amounts of impurities can be directly measured.

Koo, Jackson C. (San Ramon, CA); Yu, Conrad M. (Antioch, CA)

2002-01-01

17

Glow-worms  

Microsoft Academic Search

SHELLEY sings of a ``glow-worm golden in a dell of dew,'' but last night, at 10 o'clock, while travelling on a bridle path among the bleak lonely mountains of Tynron, Dumfriesshire, bearing up against a high wind with cold rain, I espied three glow-worms shining among the grass and ferns. I had seen them in the same locality before, but

J. S

1879-01-01

18

Bifurcations of current transfer through a collisional sheath with ionization and self-organization on glow cathodes.  

PubMed

A bifurcation analysis is performed of a dc glow discharge between parallel electrodes and of a dc near-cathode space-charge sheath bordering a uniform plasma column. A model of plasma is considered with a single ion species and motion of the charged particles dominated by drift. Bifurcation points are found at which steady-state modes with spots on the cathode branch off from the abnormal mode or from the mode corresponding to the falling section of the current-density-voltage characteristic. In both discharge configurations, bifurcations in the abnormal mode have been detected; an unexpected result given that loss of stability and pattern appearance in dc gas discharges are usually associated with a negative differential resistance of the discharge. The conclusion is drawn that the two most important mechanisms governing appearance of patterns on glow cathodes, which are electrostatic mechanism and diffusion, produce competing effects: the former favors appearance of modes with multiple spots, while the latter favors appearance of a mode with one spot. This may explain the appearance in experiments of a normal spot or, alternatively, of patterns with multiple spots. PMID:18517534

Benilov, M S

2008-03-24

19

Numerical Study on Glow Discharge of IEC Fusion  

SciTech Connect

An inertial electrostatic confinement (IEC) fusion device is possibly used for the neutron source that has the ability to produce the neutrons of 10{sup 5}-10{sup 8}/s by the glow discharge. It works more efficiently at the condition of the high voltage and the low pressure. It, however, is difficult to keep the continuous operation at the low-pressure because the glow discharge is apt to be unstable. We have made the three-dimensional Monte Carlo PIC code including atomic processes to investigate the glow discharge. The study reveals the spatial position where the ionization occurs and numerically reproduces the discharge called 'star mode'.

Osawa, Hodaka; Tabata, Takehiro; Ohnishi, Masami [Kansai University (Japan)

2005-05-15

20

Science Nation: Glowing Squid  

NSDL National Science Digital Library

In deep ocean waters, it's sometimes difficult to hide from predators. That's why so many sea creatures have evolved extraordinary methods of disguise. Cephalopods, such as octopus, squid and cuttlefish, are big on camouflage, by day or night. In fact, the Hawaiian bobtail squid has several means of stealthy self- preservation. With support from the National Science Foundation (NSF), a team from the University of Wisconsin-Madison study one bobtail squid camouflage scheme; one that glows in the dark!

21

Asymmetric superradiant scattering and abnormal mode amplification induced by atomic density distortion.  

PubMed

The superradiant Rayleigh scattering using a pump laser incident along the short axis of a Bose-Einstein condensate with a density distortion is studied, where the distortion is formed by shocking the condensate utilizing the residual magnetic force after the switching-off of the trapping potential. We find that very small variation of the atomic density distribution would induce remarkable asymmetrically populated scattering modes by the matter-wave superradiance with long time pulse. The optical field in the diluter region of the atomic cloud is more greatly amplified, which is not an ordinary mode amplification with the previous cognition. Our numerical simulations with the density envelop distortion are consistent with the experimental results. This supplies a useful method to reflect the geometric symmetries of the atomic density profile by the superradiance scattering. PMID:23787626

Wang, Zhongkai; Niu, Linxiao; Zhang, Peng; Wen, Mingxuan; Fang, Zhen; Chen, Xuzong; Zhou, Xiaoji

2013-06-17

22

Abnormal functional connectivity of default mode sub-networks in autism spectrum disorder patients.  

PubMed

Autism spectrum disorders (ASDs) are characterized by deficits in social and communication processes. Recent data suggest that altered functional connectivity (FC), i.e. synchronous brain activity, might contribute to these deficits. Of specific interest is the FC integrity of the default mode network (DMN), a network active during passive resting states and cognitive processes related to social deficits seen in ASD, e.g. Theory of Mind. We investigated the role of altered FC of default mode sub-networks (DM-SNs) in 16 patients with high-functioning ASD compared to 16 matched healthy controls of short resting fMRI scans using independent component analysis (ICA). ICA is a multivariate data-driven approach that identifies temporally coherent networks, providing a natural measure of FC. Results show that compared to controls, patients showed decreased FC between the precuneus and medial prefrontal cortex/anterior cingulate cortex, DMN core areas, and other DM-SNs areas. FC magnitude in these regions inversely correlated with the severity of patients' social and communication deficits as measured by the Autism Diagnostic Observational Schedule and the Social Responsiveness Scale. Importantly, supplemental analyses suggest that these results were independent of treatment status. These results support the hypothesis that DM-SNs under-connectivity contributes to the core deficits seen in ASD. Moreover, these data provide further support for the use of data-driven analysis with resting-state data for illuminating neural systems that differ between groups. This approach seems especially well suited for populations where compliance with and performance of active tasks might be a challenge, as it requires minimal cooperation. PMID:20621638

Assaf, Michal; Jagannathan, Kanchana; Calhoun, Vince D; Miller, Laura; Stevens, Michael C; Sahl, Robert; O'Boyle, Jacqueline G; Schultz, Robert T; Pearlson, Godfrey D

2010-06-02

23

Powerful glow discharge excilamp  

DOEpatents

A powerful glow discharge lamp comprising two coaxial tubes, the outer tube being optically transparent, with a cathode and anode placed at opposite ends of the tubes, the space between the tubes being filled with working gas. The electrodes are made as cylindrical tumblers placed in line to one other in such a way that one end of the cathode is inserted into the inner tube, one end of the anode coaxially covers the end of the outer tube, the inner tube penetrating and extending through the anode. The increased electrodes' surface area increases glow discharge electron current and, correspondingly, average radiation power of discharge plasma. The inner tube contains at least one cooling liquid tube placed along the axis of the inner tube along the entire lamp length to provide cathode cooling. The anode has a circumferential heat extracting radiator which removes heat from the anode. The invention is related to lighting engineering and can be applied for realization of photostimulated processes under the action of powerful radiation in required spectral range.

Tarasenko, Victor F. (Tomsk, RU); Panchenko, Aleksey N. (Tomsk, RU); Skakun, Victor S. (Tomsk, RU); Sosnin, Edward A. (Tomsk, RU); Wang, Francis T. (Danville, CA); Myers, Booth R. (Livermore, CA); Adamson, Martyn G. (Danville, CA)

2002-01-01

24

Detection of surface glow related to spacecraft glow phenomenon  

SciTech Connect

We have developed a high flux source of low energy neutral beams to study the spacecraft glow phenomena by using a biased limiter to neutralize plasma in ACT-1. Beams of nitrogen and nitrogen-oxygen mixtures with energies of 1 to 15 eV and fluxes greater than or equal to 10/sup 14//cm/sup 2//s were directed on target surfaces consisting of Z-302 and Z-306 paints. With the nitrogen beams we successfully detected a glow due to beam-surface interactions. In addition, we discovered a volume glow effect due to beam-gas interactions which may also play a role in spacecraft glow. 11 refs., 14 figs.

Langer, W.D.; Cohen, S.A.; Manos, D.M.; Motley, R.W.; Ono, M.; Paul, S.; Roberts, D.; Selberg, H.

1986-02-01

25

Modeling of asymmetric pulsed phenomena in dielectric-barrier atmospheric-pressure glow discharges  

NASA Astrophysics Data System (ADS)

Asymmetric current pulses in dielectric-barrier atmospheric-pressure glow discharges are investigated by a self-consistent, one-dimensional fluid model. It is found that the glow mode and Townsend mode can coexist in the asymmetric discharge even though the gas gap is rather large. The reason for this phenomenon is that the residual space charge plays the role of anode and reduces the gap width, resulting in the formation of a Townsend discharge.

Ha, Yan; Wang, Huijuan; Wang, Xiaofei

2012-01-01

26

Structural and Functional Abnormalities of Default Mode Network in Minimal Hepatic Encephalopathy: A Study Combining DTI and fMRI  

PubMed Central

Background and Purpose Live failure can cause brain edema and aberrant brain function in cirrhotic patients. In particular, decreased functional connectivity within the brain default-mode network (DMN) has been recently reported in overt hepatic encephalopathy (HE) patients. However, so far, little is known about the connectivity among the DMN in the minimal HE (MHE), the mildest form of HE. Here, we combined diffusion tensor imaging (DTI) and resting-state functional MRI (rs-fMRI) to test our hypothesis that both structural and functional connectivity within the DMN were disturbed in MHE. Materials and Methods Twenty MHE patients and 20 healthy controls participated in the study. We explored the changes of structural (path length, tracts count, fractional anisotropy [FA] and mean diffusivity [MD] derived from DTI tractography) and functional (temporal correlation coefficient derived from rs-fMRI) connectivity of the DMN in MHE patients. Pearson correlation analysis was performed between the structural/functional indices and venous blood ammonia levels/neuropsychological tests scores of patients. All thresholds were set at P<0.05, Bonferroni corrected. Results Compared to the healthy controls, MHE patients showed both decreased FA and increased MD in the tract connecting the posterior cingulate cortex/precuneus (PCC/PCUN) to left parahippocampal gyrus (PHG), and decreased functional connectivity between the PCC/PCUN and left PHG, and medial prefrontal cortex (MPFC). MD values of the tract connecting PCC/PCUN to the left PHG positively correlated to the ammonia levels, the temporal correlation coefficients between the PCC/PCUN and the MPFC showed positive correlation to the digital symbol tests scores of patients. Conclusion MHE patients have both disturbed structural and functional connectivity within the DMN. The decreased functional connectivity was also detected between some regions without abnormal structural connectivity, suggesting that the former may be more sensitive in detecting the early abnormalities of MHE. This study extends our understanding of the pathophysiology of MHE.

Zhong, Jianhui; Zheng, Gang; Wu, Shengyong; Zhang, Zhiqiang; Liao, Wei; Zhong, Yuan; Ni, Ling; Jiao, Qing; Zhang, Zongjun; Liu, Yijun; Lu, Guangming

2012-01-01

27

Self-Adjusting Characterization for Steady-State, Direct Current Cathode-Dominated Glow Discharge Plasmas at High Pressures  

NASA Astrophysics Data System (ADS)

A steady-state, direct-current high-pressure CH4-H2 glow discharge in a cup-shaped cathode parallel to anode configuration is investigated by using their V—I characteristics and CCD images. The discharges display an abnormal glow feature, and an expansion of a negative glow is observed on the cathode sidewall with the increasing discharge current. There exists a dependence of voltage on gas pressure for different fixed currents. The voltage decreases with gas pressure initially, and then increases conversely, which is correlated with the glow states of the cathode sidewall. This study exhibits a self-adjusting characterization for plasmas in cathode fall, which is important for maintaining steady-state, abnormal glow discharge in a relatively high pressure range.

Ding, Fang; Zheng, Shi-Jian; Ke, Bo; Tang, Zhong-Liang; Zhang, Yi-Chuan; Yang, Kuan; Xie, Xin-Hua; Zhu, Xiao-Dong

2013-08-01

28

Mechanistic investigations of shuttle glow  

SciTech Connect

A series of laboratory measurements have been performed in order to provide a mechanistic interpretation for the visible shuttle glow. These studies involved interactions in an 8 km/s oxygen atom beam with both contaminant dosed surfaces and gaseous targets. The authors conclude that visible shuttle glow arises from surface mediated O + NO recombination via a Langmuir-Hinshelwood mechanism and that the gas-phase exchange reaction O + N[sub 2] [r arrow] NO + N provides a viable source of precursor NO above surfaces oriented in the ram direction. 35 refs., 4 figs.

Caledonia, G.E.; Holtzclaw, K.W.; Krech, R.H.; Sonnenfroh, D.M. (Physical Sciences Inc., Andover, MA (United States)); Leone, A. (Lockhead Palo Alto Research Lab., CA (United States)); Blumber, W.A.M. (Hanscom Air Force Base, Bedford, MA (United States))

1993-03-01

29

Characteristics of radio-frequency, atmospheric-pressure glow discharges with air using bare metal electrodes  

Microsoft Academic Search

In this letter, an induced gas discharge approach is proposed and described in detail for obtaining a uniform atmospheric-pressure glow discharge with air in a gamma mode using water-cooled, bare metal electrodes driven by radio-frequency (13.56 MHz) power supply. A preliminary study on the discharge characteristics of the air glow discharge is also presented in this study. With this induced

Hua-Bo Wang; Wen-Ting Sun; He-Ping Li; Cheng-Yu Bao; Xiao-Zhang Zhang

2006-01-01

30

Laser optogalvanic and fluorescence studies of the cathode region of a glow discharge  

NASA Astrophysics Data System (ADS)

Various laser diagnostics are used to study the cathode-fall and negative-glow regions of a He glow discharge with a cold Al cathode. The electric field and absolute metastable densities are mapped and the gas temperature is measured over a range of current densities from a near-normal (173 V) to a highly abnormal (600 V) cathode fall. These measurements are analyzed to yield the current balance at the cathode surface, the ionization rate in the cathode-fall region, and the metastable production rate in the cathode-fall and negative-glow regions. The experimental results compare favorably with the results of Monte Carlo simulations. The density and temperature of the low-energy electron gas in the negative glow is determined by combining information from the experiments and Monte Carlo simulations.

den Hartog, E. A.; Doughty, D. A.; Lawler, J. E.

1988-09-01

31

Constricted glow discharge plasma source  

DOEpatents

A constricted glow discharge chamber and method are disclosed. The polarity and geometry of the constricted glow discharge plasma source is set so that the contamination and energy of the ions discharged from the source are minimized. The several sources can be mounted in parallel and in series to provide a sustained ultra low source of ions in a plasma with contamination below practical detection limits. The source is suitable for applying films of nitrides such as gallium nitride and oxides such as tungsten oxide and for enriching other substances in material surfaces such as oxygen and water vapor, which are difficult process as plasma in any known devices and methods. The source can also be used to assist the deposition of films such as metal films by providing low-energy ions such as argon ions.

Anders, Andre (Albany, CA); Anders, Simone (Albany, CA); Dickinson, Michael (San Leandro, CA); Rubin, Michael (Berkeley, CA); Newman, Nathan (Winnetka, IL)

2000-01-01

32

Glow in the Dark Slime  

NSDL National Science Digital Library

In this activity, create some Halloween spooky science by making glow-in-the-dark slime. Use this activity to investigate polymers and cross-linking. This activity guide includes a step-by-step instructional video. SAFETY NOTES: (1) Adult supervision is required. (2) Wearing gloves and goggles during this activity is a good idea because Borax is a poisonous, corrosive chemical. Read any safety instructions written on the container of Borax.

Center, Saint L.

2013-01-17

33

Benzene emitted from glowing charcoal.  

PubMed

Benzene was assessed as the predominant aromatic compound emitted from glowing charcoal and firewood embers. Concentrations measured above charcoal used for grilling exceeded 10 mg m(-3) at a 5% carbon dioxide level. Charcoal with a high carbon content released less benzene. Glowing wood pellets emitted less benzene than glowing firewood remainders. The emissions of ethene and propene relative to benzene were low for commercial charcoal and wood-pellet embers, but high for firewood ember. The proportions of methylbenzene and naphthalene from charcoal were typically only 10% relative to benzene, and those of benzofuran, dibenzofuran and benzonitrile were typically below 5%. The polycyclic aromatic hydrocarbon (PAH) indicator phenanthrene was below the 1% level. Adsorbent sampling and GC-MS were used for assessing all the aromatic compounds. Earlier studies of charcoal emissions have focused on carbon monoxide, PAH and dioxins. It is concluded that the carcinogenic benzene may be an even more severe health hazard to be addressed by exposure-decreasing measures. PMID:12606161

Olsson, Maria; Petersson, Göran

2003-03-01

34

Common Gamma-ray Glows above Thunderclouds  

NASA Astrophysics Data System (ADS)

Gamma-ray glows are continuous, long duration gamma- and x-ray emission seen coming from thunderclouds. The Airborne for Energetic Lightning Emissions (ADELE) observed 12 gamma-ray glows during its summer 2009 flight campaign over the areas of Colorado and Florida in the United States. For these glows we shall present their spectra, relationship to lightning activity and how their duration and size changes as a function of distance. Gamma-ray glows follow the relativistic runaway electron avalanche (RREA) spectrum and have been previously measured from the ground and inside the cloud. ADELE measured most glows as it flew above the screening layer of the cloud. During the brightest glow on August 21, 2009, we can show that we are flying directly into a downward facing relativistic runaway avalanche, indicative of flying between the upper positive and negative screening layer of the cloud. In order to explain the brightness of this glow, RREA with an electric field approaching the limit for relativistic feedback must be occurring. Using all 12 glows, we show that lightning activity diminishes during the onset of the glow. Using this along with the fact that glows occur as the field approaches the level necessary for feedback, we attempt to distinguish between two possibilities: that glows are evidence that RREA with feedback, rather than lightning, is sometimes the primary channel for discharging the cloud, or else that the overall discharging is still controlled by lightning, with glows simply appearing during times when a subsidence of lightning allows the field to rise above the threshold for RREA.

Kelley, Nicole; Smith, David; Dwyer, Joseph; Hazelton, Bryna; Grefenstette, Brian; Lowell, Alex; Splitt, Michael; Lazarus, Steven; Rassoul, Hamid

2013-04-01

35

A simulation of electron motion in the cathode sheath region of a glow discharge in argon  

Microsoft Academic Search

Electron motion in the cathode sheath region of a glow discharge in argon has been simulated for a linearly decreasing electric field using a one-dimensional computer model. Distribution functions for the electron flux crossing the sheath have been calculated for 12 values of the cathode fall between 180 and 1400 V encompassing the normal and abnormal regimes. Macroscopic variables including

R. J. Carman

1989-01-01

36

Gas flow effects on the submicrosecond pulsed atmospheric pressure glow discharges  

SciTech Connect

The influence of gas flow on the discharge characteristics in the submicrosecond pulsed dielectric barrier discharge at atmospheric pressure was investigated by a one-dimensional self-consistent kinetic model. The convection-transport mechanism of the plasma species caused by a longitudinal gas flow was integrated into flux equation. Two discharge current pulses, the positive one and the negative one, are operated in a normal glow mode and a subnormal glow mode, respectively. It is shown that the gas flow has a significant impact on the discharge characteristics, especially on the positive discharge pulse. The spatial distribution of electrons is affected by the gas flow through the convection transport mechanism.

Liu Fucheng; Zhang Dingzong; Wang Dezhen [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Ministry of Education), School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)

2010-10-15

37

MODE OF ACTION: NEUROTOXICITY INDUCED BY DEVELOPMENTAL THYROID HORMONE INSUFFICIENCY -- NEUROLOGICAL ABNORMALITIES RESULTING FROM EXPOSURE TO PROPYLTHIOURACIL.  

EPA Science Inventory

A manuscript summarizes a workshop aimed at developing a framework to determine the relevancy of animal modes-of-action for extrapolation to humans. This specific report used animal data on neurodevelopmental effects of thyroid hormone disruption to test the framework. Polyhaloge...

38

The theory of positive glow corona  

Microsoft Academic Search

A theory for the current and light pulses of positive glow corona from a point in air is presented; this phenomenon was first observed as an apparently continuous glow by Michael Faraday. Results are obtained, in concentric sphere geometry, for air at atmospheric pressure, by solving the continuity equations for electrons, positive ions, negative ions and metastable oxygen molecules, coupled

R. Morrow

1997-01-01

39

dc glow-discharge cleaning for accelerator  

SciTech Connect

Average pressure of 1 x 10/sup -11/ torr and vacuum stability are necessary for the successful operation of the proton storage rings such as ISABELLE. Vacuum degassing at high temperature and in situ bake-out will reduce the thermoout-gassing rate of the beam tubes to approx. 10/sup -13/ Tl/cm/sup 2/ sec, therefore achieving the required static pressure. The vacuum instability caused by beam-induced ion desorption can be solved by dc glow discharge cleaning. With evidence from this study, the present understanding of glow discharge in a cylindrically symmetric geometry is reviewed. Argon and argon/oxygen mixture serve as plasmas in the glow. The role of oxygen in cleaning the beam tubes during the glow discharge is demonstrated experimentally. Glow discharge cleaning with and without bake-out is also studied.

Chou, T.S.; Hseuh, H.C.

1982-01-01

40

Discharge characteristics of atmospheric-pressure radio-frequency glow discharges with argon\\/nitrogen  

Microsoft Academic Search

In this letter, atmospheric-pressure glow discharges in gamma mode with argon\\/nitrogen as the plasma-forming gas using water-cooled, bare copper electrodes driven by radio-frequency power supply at 13.56 MHz are achieved. The preliminary studies on the discharge characteristics show that, induced by the alpha-gamma coexisting mode or gamma mode discharge of argon, argon-nitrogen mixture with any mixing ratios, even pure nitrogen,

Hua-Bo Wang; Wen-Ting Sun; He-Ping Li; Cheng-Yu Bao; Xing Gao; Hui-Ying Luo

2006-01-01

41

Enhancement in ion beam current with layered-glows in a constricted dc plasma ion source  

SciTech Connect

High current mode has been discovered and investigated in a constricted dc plasma ion source. As discharge currents exceed a certain threshold, voltage to sustain the constricted dc plasma suddenly falls down to almost half of the value. In this sense, constricted dc plasmas can be sustained at much higher current than in conventional mode operation at a fixed discharge voltage. Phenomenally, several discrete layered-glows are created between an anode glow and a cathode glow. The layers are thin and divided by dark spaces where charged particles can be accelerated. In this high current mode, ion beam current density is about 100 times higher than in conventional mode at the same voltage. It is noteworthy that lower gas pressure is desirable to sustain the layered-glow mode, which is also profitable for ion source in terms of differential pumping. Ion current density exceeds 300 mA/cm{sup 2} at low discharge power of 175 W where ion density of plasma ball is estimated to be over 3.7x10{sup 12} cm{sup -3}.

Park, Yeong-Shin; Hwang, Y. S. [Department of Nuclear Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of)

2010-02-15

42

Abnormal functional connectivity between the anterior cingulate and the default mode network in drug-naďve boys with attention deficit hyperactivity disorder.  

PubMed

A previous study indicated that adults with attention deficit hyperactivity disorder (ADHD) had a decreased anti-correlation between the dorsal anterior cingulate cortex (dACC) and the default mode network (DMN). In this study, we investigated whether children with ADHD also show a decreased anti-correlation between the dACC and the DMN. We also explored the developmental characteristics of the resting-state functional connectivity (RSFC) of the dACC with the DMN in children with ADHD. Resting-state functional magnetic resonance imaging scans were obtained from a 3T scanner in 19 drug-naďve boys with ADHD and 23 controls. Compared with normal controls, the dACC in boys with ADHD showed a significantly decreased negative RSFC with the DMN, including the dorsomedial prefrontal cortex and the posterior cingulate cortex. The RSFC strength between the dACC and the posterior cingulate cortex showed a significantly negative correlation with age in normal controls, but not in boys with ADHD. This decreased anti-correlation may suggest an abnormal balance or interaction between attentional and intrinsic thoughts. Our age-related analysis suggested an abnormal development pattern of the dACC-DMN interaction in ADHD. PMID:22424873

Sun, Li; Cao, Qingjiu; Long, Xiangyu; Sui, Manqiu; Cao, Xiaohua; Zhu, Chaozhe; Zuo, Xinian; An, Li; Song, Yan; Zang, Yufeng; Wang, Yufeng

2012-03-15

43

Characteristics of thermoluminescence glow curves for materials exhibiting more than one glow peak  

SciTech Connect

The properties of thermoluminescence glow curves, containing one or more glow peaks, have been determined for situations where the assumptions invoked to obtain the usual first and second order kinetics do not apply. First order kinetics occurs only when retrapping is negligible. If more than one glow peak is present and retrapping occurs between different types of traps the glow peaks can be approximated, except in the wings, by the usual first and second order expressions; but often physically unrealistic parameters are obtained. These studies indicate that dating is best accomplished with minerals exhibiting first order kinetics. 6 figures, 1 table.

Levy, P.W.

1982-01-01

44

Discharge characteristics of atmospheric-pressure radio-frequency glow discharges with argon/nitrogen  

SciTech Connect

In this letter, atmospheric-pressure glow discharges in {gamma} mode with argon/nitrogen as the plasma-forming gas using water-cooled, bare copper electrodes driven by radio-frequency power supply at 13.56 MHz are achieved. The preliminary studies on the discharge characteristics show that, induced by the {alpha}-{gamma} coexisting mode or {gamma} mode discharge of argon, argon-nitrogen mixture with any mixing ratios, even pure nitrogen, can be employed to generate the stable {gamma} mode radio-frequency, atmospheric-pressure glow discharges and the discharge voltage rises with increasing the fraction of nitrogen in the argon-nitrogen mixture for a constant total gas flow rate.

Wang Huabo; Sun Wenting; Li Heping; Bao Chengyu; Gao Xing; Luo Huiying [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); School of Public Health and Family Medicine, Capital University of Medical Sciences, Beijing 100069 (China); Beijing Center for Diseases Control and Prevention, Beijing 100013 (China)

2006-10-16

45

A large gap of radio frequency dielectric barrier atmospheric pressure glow discharge  

SciTech Connect

A large gap was acquired between electrodes (up to 5.5 mm) of Ar atmospheric pressure glow discharge in radio frequency dielectric barrier discharge (rf-DBD). The discharge of Ar plasma was characterized by I-V curve and Lissajous plot, and the effective power of the discharge was calculated based on the measured Lissajous plot and found to be higher than 90% of the input power. To gain a thorough understanding of the mechanism, the rf-DBD with a single dielectric barrier layer operating in gamma mode glow discharge of N{sub 2} plasma was diagnosed in spatial resolution through optical emission spectroscopy. It was concluded that secondary electron emission might be responsible for the sustainable glow discharge in the large gap rf-DBD plasma.

Li, B.; Chen, Q.; Liu, Z. W. [Laboratory of Plasma Physics and Materials, Beijing Institute of Graphic Communication, Beijing 102600 (China)

2010-01-25

46

Infrared spectral measurement of space shuttle glow  

SciTech Connect

Infrared spectral measurements of the space shuttle glow were successfully conducted during the STS-39 space shuttle mission. Analysis indicates that NO, NO[sup +], OH, and CO are among the molecules associated with the infrared glow phenomenon. During orbiter thruster firings the glow intensities in the infrared are enhanced by factors of 10x to 100x with significant changes in spectral distribution. These measurements were obtained with the Spacecraft Kinetic Infrared Test (SKIRT) payload which included a cryogenic infrared circular variable filter (CVF) spectrometer (0.6 [mu]m to 5.4 [mu]) and a number of infrared, visible, and ultraviolet radiometers (0.2 [mu]m to 5.4 [mu]m and 9.9 [mu]m to 10.4 [mu]m). In addition, glow measurements were unsuccessfully attempted with the Cryogenic Infrared Radiance Instrumentation for Shuttle (CIRRIS-1A) with its 2.5 [mu]m to 25 [mu]m Fourier transform interferometer. SKIRT CVF obtained over 14,000 spectra of quiescent shuttle glow, thruster enhanced shuttle glow, upper atmosphere airglow, aurora, orbiter environment, and deep space non-glow backgrounds during its eight day mission. The SKIRT radiometers operated almost continuously throughout the mission to provide a detailed history of the IR/VIS/UV optical environment associated with the operation of large spacecraft structures in low earth orbit. This dissertation will primarily address those measurements conducted by the SKIRT spectrometer as they relate to space shuttle glow in the infrared. The STS-39 Space Shuttle Discovery was launched from the NASA Kennedy Space Center on 28 April 1991 into a 57 degree inclination circular orbit at an altitude of 260 km.

Ahmadijian, M.

1992-01-01

47

Characterization of millimeter magnitude atmospheric pressure glow discharge in pin-to-plane dielectric barrier discharge  

NASA Astrophysics Data System (ADS)

Discharge mode in pin-to-plane dielectric barrier discharge at atmospheric pressure was investigated by means of the electrical measurement, the photo-electricity and the fast macro photography. The discharge was operated in atmospheric air. Streamer and glow discharge were generated in the positive half-period and negative half-period of discharge respectively with a 10 kHz AC power supply when the applied voltage reached a high value. The subject of this paper is the study of the characterization of the glow discharge. It was found that the glow discharge have the hierarchical structure, although the discharge gap is small (only 0.9 mm). The positive column is shortened as the distance of discharge gap decreases, but the dimensions of other discharge area do not change. The discharge current waveform illustrates that the positive half-period discharge current is very short, which is streamer current waveform, and the negative half-period one is longer, which is glow discharge current waveform. The photo-electricity signal waveform corresponds with discharge current waveform. Two main glow discharge generating reasons are proposed in this paper. One is a sufficient number of space charge produced in the very uneven electric field around needle electrode; the other is the effective secondary electron emission process on the exposed needle electrode.

Yu, Z.; Zhang, Z. T.; Xu, S. J.; Yao, J.; Yu, Q. X.; Li, Y. J.; Zhao, J. S.

2013-03-01

48

Monte Carlo simulation of electron motion in the cathode region of a magnetron glow discharge in argon  

Microsoft Academic Search

The motion of electrons in the cathode region of a magnetron glow discharge in low-pressure argon has been studied by Monte Carlo simulation. The influences of the transverse magnetic field on energy distribution of electron flux and ionization have been investigated for normal and abnormal discharges. It has been shown that the magnetic field increases collisions, and consequently decreases the

Jun Li; Qing-Ming Chen; Zai-Guang Li

1995-01-01

49

Mass dependency of turbulent parameters in stationary glow discharge plasmas  

NASA Astrophysics Data System (ADS)

A direct current glow discharge tube is used to determine how mass changes the effects of certain turbulence characteristics in a weakly ionized gas. Helium, neon, argon, and krypton plasmas were created, and an axial magnetic field, varied from 0.0 to 550.0 Gauss, was used to enhance mass dependent properties of turbulence. From the power spectra of light emission variations associated with velocity fluctuations, determination of mass dependency on turbulent characteristic unstable modes, energy associated with turbulence, and the rate at which energy is transferred from scale to scale are measured. The magnetic field strength is found to be too weak to overcome particle diffusion to the walls to affect the turbulence in all four types of plasmas, though mass dependency is still detected. Though the total energy and the rate at which the energy moves between scales are mass invariant, the amplitude of the instability modes that characterize each plasma are dependent on mass.

Titus, J. B.; Wiggins, D. L.; Alexander, A. B.; Johnson, J. A.

2013-05-01

50

Decontamination Using a One Atmosphere Uniform Glow Discharge Cold Plasma.  

National Technical Information Service (NTIS)

Atmospheric Glow Technologies is developing an innovative mobile atmospheric plasma decon system based upon the patented one atmosphere uniform glow discharge plasma (OAUGDP) technology. This advanced system will be a deployable military protection system...

K. Kelly-Wintenberg

2002-01-01

51

Deposition and Examination of Glow Discharge Produced Amorphous Hydrogenated Germanium  

NASA Astrophysics Data System (ADS)

This thesis presents the results of extensive studies of the deposition and examination of amorphous hydrogenated germanium (a-Ge:H) thin films deposited from an rf glow discharge of GeH_4 and H_2 gases. For the purpose of these studies, a diode-type capacitively coupled glow discharge system was constructed. Results are presented of the measurements of film stress for a large number of a-Ge:H films. The stress is found to vary from high tensile (+6.6 kbar) to high compressive (-7.8 kbar), and correlates with total hydrogen content, microstructure and photoconductivity. The origin of these stresses is considered and discussed in the context of other measurements. The effects of air exposure and annealing are demonstrated. Two examples are given of the effects of varying a deposition parameter on the film properties; the effects of varying the electrode gap and the power. By piecing together extensive measurements of optical, electronic and structural properties, the electrode gap study is used to demonstrate the link between structure and electronic transport, and to clarify an earlier model of a-Ge:H film structure. The results suggest a strategy for further optimization of a-Ge:H optoelectronic properties by adjusting growth conditions to reduce the formation of columnar-type microstructure. Finally, a basic examination of the GeH _4 + H_2 glow discharge is presented. Using measurements of the DC and rf cathode potentials, it is determined that the discharges used to deposit a-Ge:H are in the so called gamma mode in which the discharge characteristics are dominated by ion-induced electron emission (gamma electrons) from the cathode. The, using a residual gas analyzer (RGA), an examination is made of discharge chemistry which centers around a comparison of SiH _{rm 4} + H_2 chemistry. Significant differences between SiH _{rm 4} + H _2 and GeH_4 + H _2 chemistry are demonstrated, and possible explanations are discussed. Measurements were then made to determine the changes which occur in the glow discharge when the electrode gap and power are varied. The results of the electrode gap study suggest that beneficial discharge chemistry is promoted by a higher kinetic energy of the electrons in the discharge.

Wickboldt, Paul

1993-01-01

52

Electrical properties of pulsed glow discharge Two new aspects  

NASA Astrophysics Data System (ADS)

At the application of pulsed glow discharge (PGD) a transient power of several kW can be reached. This leads to a significant increase of the excitation and ionization efficiency of the sputtered sample atoms. Moreover, with pulsed mode temporally resolved optical emission spectrometry (OES) and mass spectrometry (MS) deliver additional information about the chemical bonds (Harrison 1998, Bengtson et al. 2000, Hang et al. 1996, Klingler et al. 1990, Lewis et al. 2001, Jackson and King 2003). However, the practical application of pulsed glow discharge (PGD) requires an understanding of the processes taking place in the pulsed system. There are some publications, where attention was paid on the voltage current characteristics and the current signal shape of PGD (King and Pan 1993, Lewis et al. 2003). Nevertheless more attention should be paid on the electrical properties of the PGD. In this work the shapes of current, voltage and emission intensity signals, obtained with two different pulse generators are compared. For better understanding of processes, taking place in the discharge the knowledge of the gas temperature is very important. Several authors have mentioned that heating of the cathode leads to changes of the voltage current curve, mainly a decrease of the current at the same voltage. This can be explained by a lower gas density at the same pressure but at higher temperatures (Chenlong et al. 1999, Tian and Chu 2001, Kasik et al. 2002). This phenomenon gives an approach to estimate the gas temperature of the plasma.

Efimova, V. V.; Voronov, M. V.; Hoffmann, V.; Eckert, J.

2008-07-01

53

Multifunctional glow discharge analyzer for spacecraft monitoring  

Microsoft Academic Search

In this study the main objective was to develop and demonstrate a glow discharge microplasma coupled to a miniature spectrometer for detection of fire signatures from pyrolyzing and burning spacecraft materials. Our experimental results demonstrate that combustion-produced carbonaceous aerosols can serve to identify the burning materials. Demonstrating versatility for chemistry analysis, the plasma detector could differentiate carbonaceous aerosols with different

Jane H. Fujiyama-Novak; Amrita Mukherjee; Ganesh Rahul Bhimanapati; Chethan Kumar Gaddam; Randall L. Vander Wal; Benjamin Ward

54

Electron heating in atmospheric pressure glow discharges  

Microsoft Academic Search

The application of nanosecond voltage pulses to weakly ionized atmospheric pressure plasmas allows heating the electrons without considerably increasing the gas temperature, provided that the duration of the pulses is less than the critical time for the development of glow-to-arc transitions. The shift in the electron energy distribution towards higher energies causes a temporary increase in the ionization rate, and

Robert H. Stark; Karl H. Schoenbach

2001-01-01

55

Surveyor observations of lunar horizon-glow  

Microsoft Academic Search

Each of the Surveyor 7, 6, and 5 spacecraft observed a line of light along its western lunar horizon following local sunset. It has been suggested that this horizon-glow (HG) is sunlight, which is forward-scattered by dust grains (~ 10µ in diam, ~ 50 grains cm-2) present in a tenuous cloud formed temporarily (? 3 h duration) just above sharp

J. J. Rennilson; D. R. Criswell

1974-01-01

56

Characteristics of a LaB6 hollow cathode in the glow-arc transition  

NASA Astrophysics Data System (ADS)

A new type of a simple LaB6 hollow cathode tube allows us to have very stable discharge even in the regime of the glow-arc transition, which is commonly unstable for widely used cathode materials (Ta,W). Because of the relatively large size of our device (25 mm diameter) and the low-temperature operation (~1400 K), we were able to investigate various plasma parameters of the internal plasma in detail by using a standard Langmuir probe and an ion sampling technique with a tiny orifice (1 mm diameter) to study the ion behavior near the cathode wall. Our measurements of the electron-energy distribution function F(?), the space potential ?, the mean electron energy ?Ż, the electron density ne, and the sampling ion current density Ji were carried out under various discharge conditions in order to understand the basic characteristics of hollow cathode discharge. We have found that these plasma parameters show anomalous properties in the glow-arc transition: (1) The different discharge regime of hollow cathode discharge, namely the abnormal glow, the arc, and the glow-arc transition, are clearly distinguished, and the discharge voltage Vd and Ji are a unique function of the discharge current in our hollow cathode tube. (2) A distinct high-energy component appears in the range ~1-7 eV, with two types of high-energy tails. (3) The local growth of ?Ż, the local ionization, and appearance of the space potential hill are observed near the anode and central region of the tube. These anomalous disturbances correspond to nonuniform self-heating: the nonuniform thermionic electron-emission effect along the LaB6 hollow cathode tube in the glow-arc transition.

Tonegawa, Akira; Takayama, Kazuo

1990-10-01

57

Atmospheric pressure radio frequency glow discharges in argon: effects of external matching circuit parameters  

NASA Astrophysics Data System (ADS)

Numerical simulations of radio frequency atmospheric pressure argon glow discharges were performed using a one-dimensional hybrid model. The discharge simulations were carried out for a parallel plate electrode configuration with an inter-electrode gap of 1.0 mm together with an external matching circuit. The external matching circuit parameters were found to have significant effect on the discharge characteristics. The results indicate that the discharge can operate at either the ? or ? mode depending on the matching circuit parameters. The two modes of operation were found to be distinctly different. The predicted Ar* density was considered to provide qualitatively the visual appearance of the ? or ? mode discharge. The ? mode was found to have a luminous region in the center of the discharge. On the other hand, the ? mode had luminous regions very close to the electrodes which were followed by alternating dark and bright regions. The appearance of the simulated ? mode was found to resemble that of an atmospheric pressure direct current glow discharge. The predicted gas temperature indicated the ? mode to have higher gas temperature compared with the ? mode.

Farouk, Tanvir; Farouk, Bakhtier; Gutsol, Alexander; Fridman, Alexander

2008-08-01

58

Spatially resolved observation of a radio-frequency-powered glow discharge plasma for emission spectrometric analysis.  

PubMed

In glow discharge optical emission spectrometry, two-dimensional emission images for iron atomic lines were measured by using an imaging spectrograph equipped with a CCD detector, when a radio-frequency (r.f.) power source was employed for excitation. Emission images at the Fe I 371.99-nm and the Fe I 375.82-nm lines, having different excitation energies, were analyzed by the two-line method to obtain the spatial distribution of the excitation temperature in the plasma. Their emission intensities had a concentric-circle-like distribution along the radial direction of the plasma to become weaker towards the surrounding portion, which was very similar to a direct-current (d.c.) glow discharge plasma. On the other hand, the spatial distribution in the excitation temperature became relatively uniform over the central portion of the plasma, also being analogous between the r.f. and the d.c. glow discharge plasmas. These results imply that there is a major excitation process that occurs in a glow discharge plasma regardless of the power modes. PMID:23665634

Oka, Ryuichiro; Wagatsuma, Kazuaki

2013-01-01

59

Lissajous figures of glow and filamentary dielectric barrier discharges under high frequency voltage at atmospheric pressure in helium  

Microsoft Academic Search

Dielectric barrier discharges (DBD) under 11.87 kHz voltages were carried out in helium or air at atmospheric pressure. Applied voltage and current pulses, Lissajous figures were measured, and discharge images were taken by ICCD in an exposure time of ns orders. Lissajous figures of glow and filamentary DBDs were investigated. The results show that the mode at the inception of

Yanpeng Hao; Jianyang Chen; Lin Yang; Xiaolei Wang

2009-01-01

60

Analysis of Energetic Species Caused by Contact Glow Discharge Electrolysis in Aqueous Solution  

NASA Astrophysics Data System (ADS)

Contact glow discharge electrolysis is a non-Faradaic electrochemical process with an abnormal relationship between the current and voltage. Hydroxyl radicals, hydrogen radicals and hydrogen peroxide can be produced under the glow discharge, which are often used to degrade organic contaminants in aqueous solution. In this study, with 4-nitrophenol taken as an example of contaminants and tert-butanol as a scavenger of hydroxyl radicals, the role of energetic species in degrading organic compounds was examined in detail. Moreover, the effects of the applied voltage, solution conductivity and pH on the formation of three energetic species were also observed. The formation rate constants of the three energetic species were calculated based on the experimental data.

Gao, Jinzhang; Wang, Aixiang; Fu, Yan; Wu, Jianlin; Ma, Dongping; Guo, Xiao; Li, Yan; Yang, Wu

2008-02-01

61

Abnormal posturing  

MedlinePLUS

People with abnormal posturing almost always have reduced consciousness. Anyone who shows symptoms of abnormal posturing should ... Elsevier; 2008:chap 5. Bleck T. Levels of consciousness and attention. In: Goetz, CG, ed. Textbook of ...

62

Walking abnormalities  

MedlinePLUS

Gait abnormalities ... of how a person walks is called the gait. Many different types of walking problems occur without ... Some walking abnormalities have been given names: Propulsive gait -- a stooped, stiff posture with the head and ...

63

Glow discharge amorphous silicon tin alloys  

Microsoft Academic Search

We present basic density of states, photoresponse, and transport measurements made on low bandgap s-SiSn:H alloys produced by RF glow discharge deposition of SiH4, H2 and Sn(CH3)4. Major changes in the local bonding structure and the density of states are demonstrated, yet the normalized photoresponse remains poor. It is shown that two types of defect levels are produced with Sn

A. H. Mahan; B. von Roedern; A. Madan; A. Sanchez; D. L. Williamson

1984-01-01

64

Evaluation of Thermal Activation Energies from Glow Curves  

Microsoft Academic Search

A new method for the evaluation of thermal activation energies from glow curves of excited crystals is described. Use is made of the symmetry of the glow peak, from which the activation energy is calculated by a simple formula: E=(qdelta)kTg2, where Tg is the peak temperature, k-Boltzmann's constant, delta-the half-width towards the falloff of the glow peak, and q-a factor

A. Halperin; A. A. Braner

1960-01-01

65

A Study of Glow Discharge Polymerization as a Means of Modifying the Surface of Polymers.  

National Technical Information Service (NTIS)

The modification of polymer surfaces to improve blood compatibility by glow discharge polymerization which lay down an ultrathin layer of coating or unique material (glow discharge polymerized polymer) was investigated. When glow discharge polymer is appl...

H. Yasuda

1975-01-01

66

Improvement of materials surface properties by rf glow discharge treatment  

SciTech Connect

Materials surface properties were improved by the application of a rf glow discharge treatment for vacuum and electronic applications. The surface morphology was studied under different glow discharge treatments and it could be shown by experiments that the roughness of materials surface varied due to the glow discharge treating process and that a clean and smooth surface could be obtained after the treatment. The experimental results revealed that the outgassing rates for different gases decreased and the evacuating properties for the materials improved following the application of the glow discharge treatment.

Huang, T.B.; Chen, X.; Tian, X.Q.; Cha, L.Z. [Department of Electronic Engineering, Tsinghua University, Beijing 100084 (China)

2006-07-15

67

Experimental investigations of dust levitation in a DC glow discharge  

NASA Astrophysics Data System (ADS)

Dusty plasmas continue to be of considerable interest to both the astrophysical and plasma processing communities. We recently constructed a DC glow discharge source to investigate dust behavior and its effect on the plasma parameters. The system, roughly based upon one reported elsewhere(1) consists of a 4" stainless steel cross with two planar stainless steel electrodes. Both the anode and cathode are biased with respect to the chamber ground. Typical values are 100 V and -410 V, respectively with argon as the working gas and 1.5 cm electrode distance. The silica dust particles are 3 - 5 microns in diameter and rested on a stainless tray that could be electrically isolated, biased, or grounded. Clouds were observed by scattering light from a He-Ne laser into a CCD camera and the plasma diagnosed by a Langmuir probe. A variety of dust modes are observed, including dust acoustic and dust lattice modes. We report on our initial results investigating the charging of the dust grains and the sheath structure surrounding the dust cloud. (1)Thomas, E., Watson, M., Phys. Plasmas, 7, 3194 (2000)

Sheth, Niraj; Behrend, Christina; Jiang, Feng; Post-Zwicker, Andrew

2003-10-01

68

Resonance glow of the neutral interplanetary gas  

NASA Astrophysics Data System (ADS)

The neutral hydrogen, embedded in the partially ionized local interstellar medium, can enter deeply into the heliosphere with the interstellar wind flow. While entering into the heliosphere it suffers from intense charge-exchange interactions with the solar wind protons. This charge-exchange leads to a fractional depletion of the interstellar hydrogen atoms inside the heliosphere and modulates their velocity and temperature distribution. The resulting thermodynamical conditions of the interstellar hydrogen inside the heliosphere are described by two kinetic density models. The first model by Wu & Judge specially takes into account the influence on hydrogen due to solar photo ionization and solar gravitation and leads to appropriate results in the solar vicinity. The second model by Osterbart & Fahr takes into account the plasma interaction effects near the solar wind shock region and near the heliopause. Hence, this model gives more realistic results for the hydrogen properties far away from the Sun. Besides these theoretical modelings of the interplanetary hydrogen, measurements of the interplanetary hydrogen HI-Lyman-Alpha resonance glow were performed and attempts have been made to deduce the relevant thermodynamical parameter of the neutral interstellar hydrogen by analyzing these glow data. Two radiation transport models will be discussed which are used to analyze the interplanetary hydrogen HI-Lyman-Alpha resonance glow data. First, the "optically thin" approximation which is used very often in the literature because of its simple numerical handling. Unfortunately, this model has a very limited region of validity. The second radiation transport model by Scherer & Fahr introduces the exact redistribution function which takes into account the local thermodynamical conditions of the scattering agent, like density, bulk velocity and temperature of the neutral interplanetary hydrogen. Also it takes into account the actually observed solar HI-Lyman-Alpha emission profile. Therefore it is a significant improvement with respect to the "optically thin" approximation but causes much more numerical efforts.

Scherer, Horst

2000-05-01

69

Alternating-current glow and pseudoglow discharges in atmospheric pressure  

Microsoft Academic Search

Stabilization and control of alternating-current glow and pseudoglow discharges have been studied in atmospheric pressure static air and methane flow gas by a pin-to-pin configuration. The electrode configuration and input power control the amplitude and duration of the discharge current and current pulses. Glow and pseudoglow discharges have been applied to the methane conversion.

Yun Yang

2003-01-01

70

Development of the Methan Glow Discharge System on JT-60.  

National Technical Information Service (NTIS)

Methan glow discharge system on JT-60 was developed to coat carbon on the surface of the first wall. The objective of this system is to produce the carbon coating on the surface of the first wall and to make the glow discharge for the treatment of the fir...

K. Kawasaki H. Hiratsuka Y. Miyo T. Kuroda K. Ohta

1987-01-01

71

Protein destruction by atmospheric pressure glow discharges  

SciTech Connect

It is well established that atmospheric pressure glow discharges are capable of bacterial inactivation. Much less known is their ability to destruct infectious proteins, even though surgical instruments are often contaminated by both bacteria and proteinaceous matters. In this letter, the authors present a study of protein destruction using a low-temperature atmospheric dielectric-barrier discharge jet. Clear evidences of protein removal are presented with data of several complimentary experiments using scanning electron microscopy, electron dispersive x-ray analysis, electrophoresis, laser-induced fluorescence microscopy, and protein reduction kinetics. Considerable degradation is observed of protein fragments that remain on their substrate surface after plasma treatment.

Deng, X. T.; Shi, J. J.; Chen, H. L.; Kong, M. G. [Department of Electronic and Electrical Engineering, Loughborough University, Loughborough, Leicestershire LE11 3TU (United Kingdom); MRC Toxicology Unit, University of Leicester, Leicester, Leicestershire LE1 9HN (United Kingdom); Department of Electronic and Electrical Engineering, Loughborough University, Loughborough, Leicestershire LE11 3TU (United Kingdom)

2007-01-01

72

Experimental verification of dynamics modulation in a periodically-driven neon glow discharge plasma  

NASA Astrophysics Data System (ADS)

Two ionization wave modes in a driven neon glow discharge alternate as the dominant mode as their response to the driving force alternates between spatiotemporal and temporal periodic pulling. This phenomenon, termed dynamics modulation, was first noted by Koepke, Weltmann, and Selcher [1], who saw two limited but representative cases and proposed a mechanism [2] by which it occurs. Dynamics modulation is reproduced experimentally in a neon glow discharge plasma. The system is periodically driven near a non-dominant mode using a narrow-band ring dye laser tuned to a wavelength near the metastable neon transition at 588.35 nm. A spatially-fixed photodiode with a narrow band filter that selectively passes the primary neon spectral line at 640 nm is used to acquire the time series of luminosity oscillations. These experimental data are used to verify the proposed mechanism and explore the resulting implications for spontaneous unidirectional mode transitions that occur with a change in discharge current.[4pt] [1] M. E. Koepke, K.-D. Weltmann, and C. A. Selcher, Bull. Am. Phys. Soc. 40, 1716 (1995).[0pt] [2] K. -D. Weltmann, M. E. Koepke, and C. A. Selcher, Phys. Rev. E 62, 2773, (2000).

Miller, P. M.; Koepke, M. E.; Gunell, H.

2010-11-01

73

Characteristics of low frequency air glow dielectric barrier discharges at atmospheric pressure  

NASA Astrophysics Data System (ADS)

In this paper we present recent studies of dielectric barriers discharges in air. The discharges are generated using an AC power supply operating at a relatively low frequency of 60 Hz between two sheets of porous dielectric material of varying thickness measuring 20 mm x 20 mm in area. Measurements are made of the optical emission and voltage--current waveforms from which we extract discharge properties including electron density, under different input voltage, electrode separation, and dielectric thickness. Stable and continuous air glow discharges were obtained at atmospheric pressure in the range of 2--5 kV and current densities of a few mA for 0.5--2.5 mm discharge gaps. Regions of stable glow discharges are mapped out and a plausible mechanism is described for the transition from glow to streamer mode. The experimental results are compared to one-dimensional numerical simulations that are carried out for a discharge pressure range of 100--760 Torr.

Hwang, Nakyung; Im, Seong-Kyun; Bak, Moon Soo; Cappelli, Mark A.

2012-10-01

74

Craniofacial Abnormalities  

MedlinePLUS

... of the skull and face. Craniofacial abnormalities are birth defects of the face or head. Some, like cleft ... palate, are among the most common of all birth defects. Others are very rare. Most of them affect ...

75

Congenital Abnormalities  

MedlinePLUS

... only. Girls may carry the abnormal gene that causes these disorders but not show the actual disease. (Examples of this problem include hemophilia, color blindness, and the common forms of muscular ...

76

The theory of positive glow corona  

NASA Astrophysics Data System (ADS)

A theory for the current and light pulses of positive glow corona from a point in air is presented; this phenomenon was first observed as an apparently continuous glow by Michael Faraday. Results are obtained, in concentric sphere geometry, for air at atmospheric pressure, by solving the continuity equations for electrons, positive ions, negative ions and metastable oxygen molecules, coupled with Poisson's equation. A series of `saw-toothed' current pulses of period about 0022-3727/30/22/008/img1 is predicted with a DC current level. Accompanying the current peaks are discrete pulses of light 30 ns wide. Successive `shells' of positive ions, from successive current pulses, carry 96% of the mean current. The mean current - voltage relationship has the classic square-law form. The seed electrons required for successive pulses are detached from negative ions by metastable oxygen molecules. Photo-ionization is crucial for the discharge at the anode and for the formation of negative ions throughout the gap. The pulse frequency varies with applied voltage and is found to be approximately proportional to the positive-ion mobility. The surface electric field at the central electrode remains close to Peek's onset field. The origin of onset streamers is explained and sub-microsecond voltage pulses are found to produce streamers. The results for concentric-cylinder electrodes are described briefly.

Morrow, R.

1997-11-01

77

Optical bleaching and radiation response of feldspar TL glow peaks separated by using computerized glow curve deconvolution  

NASA Astrophysics Data System (ADS)

The thermoluminescence (TL) peaks of feldspar were separated using the computerized glow curve deconvolution (CGCD) method combined with the second-derivative technique and were investigated not only for bleaching with different light sources (blue and infrared) but also for luminescence response to radiation dose. In the results, the TL glow peak was separated into four peaks at 280 °C, 315 °C, 360 °C, and 440 °C. Each separated TL glow peak exhibited two exponential decays in the signal bleached using blue or infrared stimulation. In view of all four separated glow peaks, the bleaching of the first (second) exponential component was faster (slower) for both the blue and the infrared stimulation as the peak temperature increased, and the bleaching of the first (second) exponential component with blue stimulation was faster (slower) than that with infrared stimulation. In addition, we found that with added beta dose, the shapes of the growth curves showed no substantial differences for the separated glow peaks.

Kim, Ki-Bum; Hong, Duk-Geun

2012-08-01

78

Abnormal functional connectivity between the anterior cingulate and the default mode network in drug-naďve boys with attention deficit hyperactivity disorder  

Microsoft Academic Search

A previous study indicated that adults with attention deficit hyperactivity disorder (ADHD) had a decreased anti-correlation between the dorsal anterior cingulate cortex (dACC) and the default mode network (DMN). In this study, we investigated whether children with ADHD also show a decreased anti-correlation between the dACC and the DMN. We also explored the developmental characteristics of the resting-state functional connectivity

Li Sun; Qingjiu Cao; Xiangyu Long; Manqiu Sui; Xiaohua Cao; Chaozhe Zhu; Xinian Zuo; Li An; Yan Song; Yufeng Zang; Yufeng Wang

79

Modeling RF Glow Discharges for Microelectronics Manufacturing Processes.  

NASA Astrophysics Data System (ADS)

The semiconductor industry is dependent on the use of plasma processing techniques for many steps in the manufacture of integrated circuits. Despite their heavy use, plasma processes remain relatively poorly understood. Computer models of these processes show great promise as a means of gaining more knowledge about these processes. The work presented in this thesis is aimed at developing rf glow discharge models for simulating reactive ion etching. Two rf glow discharge models are presented. The first model is based on the moments of the Boltzmann transport equation. This continuum model can be used to simulate any arbitrary mixture of gases. Swarm parameter data for this model are calculated using a Monte Carlo model which simulates a charged particle drifting in a uniform electric field. Experimental verification of the model is made with an argon rf glow discharge. Results of an oxygen rf glow discharge is also presented to show the models ability to simulate more complex discharges. The second rf glow discharge model merges particle and Monte Carlo modeling techniques. This model represents the discharge as a large swarm of particles which interact with each other through their self-generated electric field and with the neutral background gas through random collisions. Because of the few assumptions used to formulate the model, it is valid for all rf glow discharge operating conditions. Results from simulations with this model are compared with results from the continuum rf glow discharge model and with experimental measurements.

Trombley, Henry William

1991-02-01

80

Particle beam glow discharge mass spectrometry: spectral characteristics of nucleobases.  

PubMed

Use of a particle beam glow discharge (PB-GD) source for mass spectrometric determinations of deoxy- and ribonucleosides and nucleotides is described. Use of this combination of sample introduction and ion source decouples the vaporization and ionization steps, leading to very simple spectral structure. The mass spectra of these compounds are EI-like in nature, with clearly identified molecular ions and fragmentation patterns that are easily rationalized. The PB-GDMS combination can be operated in a flow injection mode wherein the analyte is injected directly into the solvent flow, or can also be coupled to a high-performance liquid chromatography (HPLC) system allowing LC/MS analysis of mixtures. Mass spectra obtained for nucleic acid bases, nucleosides, and nucleotides are readily obtained with injections of low-nanomole quantities. Representative PB-GDMS spectra for deoxy- and ribonucleosides, nucleotides, and mixed-base oligonucleotides are presented to demonstrate the capabilities of the GD source. Characteristic fragmentation peaks from the spectra of adenine, cytosine, guanine, and thymine were identified in 22-base sequences of single-stranded DNA. The PB-GD source is capable of producing spectra that may be used to identify the individual bases present in mixed-base DNA and RNA fragments. PMID:12872280

Davis, W Clay; Venzie, Jacob L; Willis, Bert; Coffee, R Lane; Arya, Dev P; Marcus, R Kenneth

2003-01-01

81

Submicrosecond pulsed atmospheric glow discharges sustained without dielectric barriers at kilohertz frequencies  

NASA Astrophysics Data System (ADS)

In this letter, the authors report the experimental observation of a large-volume atmospheric glow discharge sustained without dielectric barriers at 1 kHz. This barrier-free mode of operation is made possible with a submicrosecond pulsed excitation instead of the usual sinusoidal excitation. Its current-voltage characteristics are shown to be very different from conventional atmospheric dielectric barrier discharges, and its generation mechanism is studied with nanosecond resolved optical emission spectroscopy. The pulsed barrier-free atmospheric plasma is shown to produce very intense atomic oxygen emission line at 777 nm, up to one magnitude more intensive than that of a comparable atmospheric dielectric barrier discharge.

Walsh, J. L.; Shi, J. J.; Kong, M. G.

2006-10-01

82

Abnormal Plasminogen  

PubMed Central

A patient who suffered a recurring thrombosis over the last 15 yr has been investigated. The only abnormality found in this patient was a significantly depressed level of plasminogen activity in plasma. In spite of the depressed plasminogen activity, the patient was found to have a normal level of plasminogen antigen concentration. It was calculated that the activity per milligram of plasminogen of the patient was approximately one-half the values of normal subjects. The same discrepancy between biological activity and antigen concentration was found in the other members of the kindred. A niece was found to have practically no plasminogen activity but possessed a normal concentration of plasminogen antigen. Both her parents were found to have approximately half the normal plasminogen activity and normal antigen levels. These studies suggested that the molecular abnormality was inherited as an autosomal characteristic, and the family members who had half the normal levels of activity with normal plasminogen antigen were heterozygotes whereas the one with practically no plasminogen activity was homozygote. Subsequent studies showed that the pattern of gel electrofocusing of purified plasminogen of the heterozygotes consisted of 10 normal bands and 10 additional abnormal bands, each of which had a slightly higher isoelectric point than each corresponding normal component. This indicates that plasminogen of the heterozygote is a mixture of normal and abnormal molecules in an approximately equal amount, which was substantiated by active site titration of purified plasminogen preparations obtained from the propositus and a normal individual. The gel electrofocusing pattern of the homozygote consisted of abnormal bands only. The defect is a hereditary abnormality of plasminogen. Images

Aoki, Nobuo; Moroi, Masaaki; Sakata, Yoichi; Yoshida, Nobuhiko; Matsuda, Michio

1978-01-01

83

Nonlinear dynamics modulation in a neon glow discharge plasma  

NASA Astrophysics Data System (ADS)

In dynamics modulation, two modes in a driven neon glow discharge alternate as the dominant mode as their response to the driving force alternates between spatiotemporal and temporal periodic pulling. This phenomenon was first noted by Koepke, Weltmann, and Selcher (Bull. Am. Phys. Soc. 40, 1716 (1995)), who saw two limited but representative cases and proposed a mechanism (Phys. Rev. E 62, 2773 (2000)) by which it occurs. The intent of this dissertation is to document experimentally and test the dynamics modulation mechanism they proposed. Using a new extension of a previous mathematical treatment of periodic pulling, the resulting experimental data are used to verify the predicted mechanism. A numerical model is also presented that reproduces the signature of dynamics modulation and further supports the validity of the mechanism. For two pairs of mode frequencies, three complete data series as driving frequency is increased are presented. Each of these data series shows the progression of the system from pure spatiotemporal behavior, through dynamics modulation, and ending at entrainment in the upper mode. Ionization wave modes are examined using time series recorded using a photodiode with a narrow band filter that selectively passes the primary neon spectral line at 640 nm. The system was periodically driven using a narrow-band ring dye laser tuned to a wavelength near the metastable neon transition at 588.35 nm. The amplitude of the driving force was decreased (increased) by tuning the laser away from (nearer to) the center of the neon line, while the driving frequency was controlled by an acousto-optic modulator chopping the laser beam at the desired frequency. Arnol'd tongue boundaries identifying the edges of frequency entrainment regions in the driving amplitude-driving frequency plane were established for four different discharge currents. The (upward) dynamics modulation behavior seen by Koepke, Weltmann, and Selcher was reproduced and additional data were acquired for two additional representative cases of downward modulations, previously undocumented. The upward modulations are used to verify the mechanism, while the downward modulations exhibit qualitatively different behavior. These differences are discussed. Two coupled van der Pol equations were chosen to model the mechanism described by Koepke, Weltmann, and Selcher, and the resulting time series was solved with a Runge-Kutta routine whose parameters could be adjusted as the simulation proceeded. The model successfully reproduces the qualitative behavior of dynamics modulation and reinforces the experimental verification of the proposed mechanism, but lacks sufficient complexity for a complete quantitative comparison.

Miller, Paul M.

84

Parametric Studies of Argon Glow Discharges  

NASA Astrophysics Data System (ADS)

The basis of this work is one-dimensional fluid model of electrical properties of a argon glow discharge with planar electrods. The results from this model are the spatial profiles of electric field, the charged particle densities, and ionization source term. The range of current densities considered is between 0.1 and 0.6 mA/cm2. To calculate the gas temperature, we solve the one dimensional heat transport equation. The gas temperature profile is reintroduced into the electrical model. In the fluid model, the electrons and ions are described by their continuity and momentum transfer equations in the drift diffusion approximation, and these equations are solved together with Poissons equation for the electric field. Key words : Plasma, Lamp, Argon, Power, Energy deposition, Modeling, Heating

Ahmed, Belasri; Khelifa, Yanallah

2003-10-01

85

Glow-discharge-driven bucket ion source  

NASA Astrophysics Data System (ADS)

A two-stage source of broad beams of gaseous ions employing a glow-discharge plasma cathode and an anode chamber with a peripheral multicusp magnetic field has been studied. A grid, whose potential approached the potential of the screen grid of the ion source, separated the cathode and anode stages. The effect of the energy (0-300 eV), the current of injected electrons (0.2-0.8 A), and the gas pressure (argon) on the plasma parameters and the efficiency of ions extraction from the plasma have been analyzed. The current density of the ions extracted from the magnetic-field-free plasma had a nearly homogeneous distribution (~10%). The beam of 3 keV argon ions was generated using a two-electrode ion optical system with the area of ~50 cm2. The beam current was 60 mA at the electron current of the plasma cathode equal to 0.2 A.

Gavrilov, N. V.; Kamenetskikh, A. S.

2004-05-01

86

Probiotic Bacteria Induce a 'Glow of Health'  

PubMed Central

Radiant skin and hair are universally recognized as indications of good health. However, this ‘glow of health’ display remains poorly understood. We found that feeding of probiotic bacteria to aged mice induced integumentary changes mimicking peak health and reproductive fitness characteristic of much younger animals. Eating probiotic yogurt triggered epithelial follicular anagen-phase shift with sebocytogenesis resulting in thick lustrous fur due to a bacteria-triggered interleukin-10-dependent mechanism. Aged male animals eating probiotics exhibited increased subcuticular folliculogenesis, when compared with matched controls, yielding luxuriant fur only in probiotic-fed subjects. Female animals displayed probiotic-induced hyperacidity coinciding with shinier hair, a feature that also aligns with fertility in human females. Together these data provide insights into mammalian evolution and novel strategies for integumentary health.

Smillie, Christopher; Varian, Bernard J.; Ibrahim, Yassin M.; Lakritz, Jessica R.; Alm, Eric J.; Erdman, Susan E.

2013-01-01

87

Vehicle/Atmosphere Interaction Glows: Far Ultraviolet, Visible, and Infrared  

NASA Astrophysics Data System (ADS)

Spacecraft glow information has been gathered from a number of spacecraft including Atmospheric and Dynamic satellites, and Space Shuttles (numerous flights) with dedicated pallet flow observations on STS-39 (DOD) and STS-62 (NASA). In addition, a larger number of laboratory experiments with low energy oxygen beam studies have made important contributions to glow understanding. The following report provides information on three engineering models developed for spacecraft glow including the far ultraviolet to ultraviolet (1400-4000 A), and infrared (0.9-40 microns) spectral regions. The models include effects resulting from atmospheric density/altitude, spacecraft temperature, spacecraft material, and ram angle. Glow brightness would be predicted as a function of distance from surfaces for all wavelengths.

Swenson, G.

1999-10-01

88

Use of DC Glow Discharges as Undergraducate Educational Tools.  

National Technical Information Service (NTIS)

Plasmas have a beguiling way of getting students excited and interested in physics. We argue that plasmas can and should be incorporated into the undergraduate curriculum as both demonstration sects. Our device, based on a direct current (DC) glow dischar...

A. Zwicker J. Ross S. Gershman S. A. Wissel

2012-01-01

89

Microsecond pulsed glow discharge as an analytical spectroscopic source  

SciTech Connect

A pulsed glow discharge, operating in the microsecond regime, has been found to be advantageous for the examination of solid samples. We have studied the spectroscopic response by atomic emission, absorption, fluorescence, and mass spectrometries. Results to date show enhanced efficiency for analytical response of the sputtered sample atoms. This type of discharge also permits acquisition of useful diagnostic information concerning glow discharge processes. 22 refs., 8 figs.

Hang, W.; Walden, W.O.; Harrison, W.W. [Univ. of Florida, Gainesville, FL (United States)

1996-04-01

90

Examination of interior surfaces using glow-discharge illumination  

DOEpatents

Endoscopic examination of the interior of a hollow structure through a light pipe that is inserted into the structure, the interior being illuminated by means of a glow discharge that is established with a high voltage applied between the structure wall as one electrode and a second electrode that is inserted into the structure, or establishing the glow with two electrodes inserted into the structure.

Lord, David E. (Livermore, CA); Petrini, Richard R. (Livermore, CA); Carter, Gary W. (Livermore, CA)

1978-01-01

91

Numerical investigation on operation mode influenced by external frequency in atmospheric pressure barrier discharge  

SciTech Connect

The influence of external driving frequency on the discharge mode in the dielectric barrier discharge was investigated with a two-dimensional, self-consistent fluid model. The simulation results show that the helium discharge exhibits three operation modes: Townsend, homogeneous glow, and local glow discharges from the lower frequency (1 kHz) to the higher frequency (100 kHz) under discharge parameters specified in this work. The discharge operates in a Townsend mode when the driving frequency varies from 1 to about 7 kHz; while it exhibits homogenous glow characteristics in an approximate range from 7 to 65 kHz; when the external frequency exceeds 65 kHz, it turns into a local glow discharge. The effects of external driving frequency on the discharge mode were revealed and the physical reasons were discussed.

Wang Qi [Dalian Institute of Semiconductor Technology, School of Electronics Science and Technology, Dalian University of Technology, Dalian 116023 (China); Sun Jizhong; Wang Dezhen [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116023 (China)

2011-10-15

92

Generation of Atmospheric-Pressure Glow Discharge and Its Applications 2.Production of Atmospheric-Pressure Glow Discharge  

NASA Astrophysics Data System (ADS)

Atmospheric-pressure glow (APG) discharge is one of the more interesting fields of recent study owing to its possible applications in plasma processing, surface treatment, sterilization, etc. This field was developed by Okazaki and Kogoma et al. of the Sophia University group in 1988, and has spread world wide. Usually, a glow discharge is difficult to keep stable at atmospheric gas pressure because glow-to-arc transition occurs due to thermalization of the plasma. However, some methods have been presented to produce stable glow plasma at atmospheric gas pressure; 1) inserting a dielectric plate between electrodes, 2) applying pulsed voltage having a pulse width shorter than the thermalization time, 3) use of a micro-hollow cathode configuration, etc. This article describes the generation of AGP mainly using the dielectric plate. Numerical analysis based on continuity equations of charged species and Poisson's equation is also described.

Takaki, Koichi; Fujiwara, Tamiya; Tochikubo, Fumiyoshi

93

Microsecond pulsed glow discharge source in ``Element GD'' and ``VG 9000'' mass-spectrometers  

NASA Astrophysics Data System (ADS)

Microsecond pulsed glow discharge (PGD) may consume several kW of instantaneous power that may lead to a significant increase of a sample atoms excitation and ionization efficiency. Improvement of analytical characteristics of a glow discharge source using pulsed mode of power supply is demonstrated earlier for different optical and mass spectral methods (Drobyshev, Turkin 1981, Bengtson et al. 2000, Huang et al. 1991, Hang et al. 1996, 1994, Farnsworth, Walters 1982), including fast flow ion source (Voronov, Hoffmann 2007). However, practical use of microsecond PGD is limited to scientific investigations. In this work the microsecond PGD is applied to existing commercial mass-spectrometers ``Element GD'' and ``VG 9000'' to develop a system, which can be used in commercial routine analysis. Investigations are focused on possibilities of analysis with microsecond PGD and in comparison of PGD in fast flow source (``Element GD'') and usual Grimm type source (``VG 9000''). Detection limits in DC and PGD modes are investigated and compared. The secondary discharge in Grimm type fast flow source was discovered in (Voronov, Hoffmann 2007), and it certainly exists in ``Element GD'' instrument. However, practical application of the secondary discharge for improvement of analytical properties of the instrument is not clear. To answer this question, dynamics of ions extracted from the discharge pulses is measured using earlier developed method (Voronov, Hoffmann 2007) (see the fig.). Based on the measured ion dynamics and results of the PGD numerical simulation, influence of the secondary discharge in ``Element GD'' instrument is discussed.

Voronov, M.; Hofmann, Th.; Venzago, C.

2008-07-01

94

The dominant developmental mutants of tomato, Mouse-ear and Curl, are associated with distinct modes of abnormal transcriptional regulation of a Knotted gene.  

PubMed Central

The Curl (Cu) and Mouse-ear (Me) mutations of tomato cause two seemingly unrelated developmental syndromes with a wide range of pleiotropic phenotypes. Yet, the distinct morphogenic alterations in shoots, leaves, and inflorescences conferred by the two mutations appear to be caused by unchecked meristematic activity that characterizes dominant mutations in Knotted1 (Kn1)-like genes of monocot plants. We have been unable to separate the two closely linked Cu and Me mutations, and they may lie in the same gene. A homeobox-containing class I Kn1-like gene, TKn2, also maps to the same location. Significantly, the dominant mutations are associated with two aberrant modes of TKn2 transcription. Overexpression of the two in-frame wild-type transcripts of TKn2 is associated with the Cu mutation, whereas misexpression of an abundant and oversized fusion mRNA is associated with the Me mutation. Available molecular evidence strongly suggests that the defective Me-TKn2 transcript is generated via a novel splicing event that merges transcripts of two closely linked genes. The translated fusion product is comprised of most of the 5' end of the adjacent PPi-dependent fructose 6-phosphate phosphotransferase (PFP) transcript spliced in-frame to coding position 64 of the TKn2 transcript, leaving the TKn2 homeobox intact. We suggest that class I Kn1-like genes were selected early during evolution to regulate basic programs of aerial meristems and that subtle alterations in their function may be the basis for the wide diversity in growth parameters of shoot systems, leaves, and inflorescences among plant species.

Parnis, A; Cohen, O; Gutfinger, T; Hareven, D; Zamir, D; Lifschitz, E

1997-01-01

95

Composite state control and magnetic properties of Co and Si cluster assemblies prepared with double-glow-discharge sources  

SciTech Connect

Using a double-glow-discharge-cluster-source system, in which one glow discharge was a dc mode and the other an rf discharge mode, Co and Si clusters were independently produced and simultaneously deposited on a substrate. When a separation plate was inserted between two glow-discharge chambers, a mixture of Co and Si clusters was obtained: small Co clusters were distributed at random, while the Si clusters were aggregated to form large secondary particles. Without inserting the separation plate, on the other hand, core-shell clusters were obtained: a Co core was surrounded by small Si crystallites. The magnetization measurement indicated that the magnetic coercive force of Co/Si core-shell cluster assemblies was much smaller than that of Co cluster assemblies in which Co clusters were covered with antiferromagnetic CoO shells, indicating that the Si shell prevented Co cluster surfaces from their oxidation. Therefore, the present double-cluster-source system is useful in fabricating various sorts of cluster composites, which cannot be prepared by conventional coevaporation or precipitation methods.

Katoh, Ryoji; Hihara, Takehiko; Peng, D.-L.; Sumiyama, Kenji [Department of Materials Science and Engineering, Nagoya Institute of Technology, Nagoya 466-8555 (Japan)

2006-08-01

96

Research Into Characteristics of X-Ray Emission Laser Beams from Solid-State Cathode Medium of High-Current Glow Discharge  

NASA Astrophysics Data System (ADS)

X-ray emissions ranging 1.2-3.0 keV with dose rate up to 1.0 Gy/s have been registered in experiments with high-current Glow Discharge. The emissions energy and intensity depend on the cathode material, the kind of plasma-forming gas, and the discharge parameters. The experiments were carried out on the high-current glow discharge device using D2, H2, Kr, and Xe at pressure up to 10 Torr, as well as cathode samples made from Al, Sc, Ti, Ni, Nb, Zr, Mo, Pd, Ta, W, Pt, at current up to 500 mA, and discharge voltage of 500-2500 V. Two emission modes were revealed under the experiments: (1) Diffusion X-rays was observed as separate X-ray bursts (up to 5 × 105 bursts a second and up to 106 X-ray quanta in a burst), (2) X-rays in the form of laser microbeams (up to 104 beams a second and up to 1010 X-ray of quanta in a beam, angular divergence was up to 10-4, the duration of the separate laser beams must be ? = 3 × 10-13-3 × 10-14 s, the separate beam power must be 107-108 W). The emission of the X-ray laser beams occurred when the discharge occurred and within 100 ms after turning off the current. The results of experimental research into the characteristics of secondary penetrating radiation occurring when interacting primary X-ray beams from a solid-state cathode medium with targets made of various materials are reported. It was shown that the secondary radiation consisted of fast electrons. Secondary radiation of two types was observed: (1) The emission with a continuous temporal spectrum in the form of separate bursts with intensity up to 106 fast electrons a burst. (2) The emission with a discrete temporal spectrum and emission rate up to 1010 fast electrons a burst. A third type of the penetrating radiation was observed as well. This type was recorded directly by the photomultiplier placed behind of the target without the scintillator. The abnormal high penetrating ability of this radiation type requires additional research to explain. The obtained results show that creating optically active medium with long-living metastable levels with the energy of 1.0-3.0 keV and more is possible in the solid state.

Karabut, Alexander B.

2006-02-01

97

Glow discharge conditioning of the PDX vacuum vessel  

SciTech Connect

A glow discharge technique has been developed and applied to the conditioning of the large (38 m/sup 3/) Poloidal Divertor Experiment (PDX) vacuum vessel. The discharge parameters and working gas (H/sub 2/) were chosen to maximize C and O removal and minimize metal sputtering. The glow discharge was produced by biasing one or two internal anodes at 400 V to sustain a discharge current of 2 to 4 A per anode. Purified H/sub 2/ at a pressure of 3 x 10/sup -2/ torr was flowed through PDX at approx. 10 t-l/s. The effectiveness of the glow discharge conditioning was monitored by measuring impurity gas (CH/sub 4/, C/sub 2/H/sub 4/, and CO) exhaust rates by mass spectrometry and C and O surface removal rates by in-situ AES and XPS.

Dylla, H.F.; Cohen, S.A.; Rossnagel, S.M.; McCracken, G.M.; Staib, P.

1980-03-01

98

Influences of impedance matching network on pulse-modulated radio frequency atmospheric pressure glow discharges  

SciTech Connect

Pulse-modulated RF atmospheric pressure glow discharges (APDGs) were investigated in recent years to reduce the thermal accumulation and extend the operation region of the stable alpha glow mode. Different pulse-modulated voltage and current waveforms were acquired in previous experiments, but no attention was paid to the interpretation. We investigated this issue and associated phenomenon via positive and negative feedback effects derived from varying the series capacitor in the inversely L-shaped matching network used in our pulse-modulated RF APGD source. The evolutions of pulse-modulated RF waveforms were found to be associated with the feedback region and the pulsed plasma absorbed RF power. In the positive feedback region, pulse-modulated RF APGDs are relatively stable. In the negative feedback region, wide spikes as well as undershoots occur in RF voltage and current waveforms and the plasma absorbed RF power. In case of a high RF power discharge with a low modulation frequency, the pulse-modulated RF APGD is extinguished and re-ignited due to the enhanced undershoot during the initial pulse phase. The pulse-modulated RF APGD can transit from positive to negative feedback region in a range of series capacitance. Experimental results are discussed by the aid of equivalent circuit, negative and positive feedback effects.

Huo, W. G. [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116023 (China); School of Physics and Electronic Technology, Liaoning Normal University, Dalian 116029 (China); Xu, K.; Sun, B.; Ding, Z. F. [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116023 (China)

2012-08-15

99

Influences of impedance matching network on pulse-modulated radio frequency atmospheric pressure glow discharges  

NASA Astrophysics Data System (ADS)

Pulse-modulated RF atmospheric pressure glow discharges (APDGs) were investigated in recent years to reduce the thermal accumulation and extend the operation region of the stable alpha glow mode. Different pulse-modulated voltage and current waveforms were acquired in previous experiments, but no attention was paid to the interpretation. We investigated this issue and associated phenomenon via positive and negative feedback effects derived from varying the series capacitor in the inversely L-shaped matching network used in our pulse-modulated RF APGD source. The evolutions of pulse-modulated RF waveforms were found to be associated with the feedback region and the pulsed plasma absorbed RF power. In the positive feedback region, pulse-modulated RF APGDs are relatively stable. In the negative feedback region, wide spikes as well as undershoots occur in RF voltage and current waveforms and the plasma absorbed RF power. In case of a high RF power discharge with a low modulation frequency, the pulse-modulated RF APGD is extinguished and re-ignited due to the enhanced undershoot during the initial pulse phase. The pulse-modulated RF APGD can transit from positive to negative feedback region in a range of series capacitance. Experimental results are discussed by the aid of equivalent circuit, negative and positive feedback effects.

Huo, W. G.; Xu, K.; Sun, B.; Ding, Z. F.

2012-08-01

100

Aqueous solution sampling and the effects of water vapor in glow discharge mass spectrometry  

Microsoft Academic Search

Glow discharge mass spectrometry is a technique for the analysis of trace elements in solid materials. In this dissertation, the sampling of small volume aqueous solution samples has been explored. This method uses electrothermal vaporization of a solution residue for atomization, while a glow discharge provides the excitation and ionization. The main advantage of this technique over other glow discharge

Ratliff

1992-01-01

101

Decomposition Of Benzene By A Low Pressure Glow Discharge  

NASA Astrophysics Data System (ADS)

Decomposition characteristics of diluted benzene with nitrogen in a low pressure DC glow discharge plasma are investigated by emission spectroscopy, mass spectrometry, infrared absorption spectroscopy, concentration measurement and gas pressure monitoring. It is likely that benzene is decomposed chiefly by electron collision, and that excite molecules of nitrogen and/or nitrogen ions do not make a large contribution to benzene destruction directly. It is found that H, H2, H3, C, CH, CH4, NH3, C2, C2H, CN, C2H2, and C2H4 are produced in the glow discharge.

Satoh, K.; Sawada, T.; Naitoh, T.; Itoh, H.; Shimozuma, M.; Tagashira, H.

2003-06-01

102

Mechanism of boriding from pastes in a glow discharge  

SciTech Connect

The authors investigate the boridation of steel 45 from the standpoint of the glow-discharge dissociation of a borax paste and the plasma arc spraying of the resulting boron into the steel. The effects of process parameters on the impregnation of boron into the steel and its phase behavior in the boridation process are discussed.

Isakov, S.A.; Al'tshuler, S.A.

1987-09-01

103

Glow discharge cleaning of carbon fiber composite and stainless steel  

Microsoft Academic Search

The paper experimentally investigates and analyses the features and mechanisms of both of oxygen removal by deuterium glow discharge from CFC, pyrolytic graphite and stainless steel subjected to irradiation in oxygen contaminated plasma. It is shown that oxygen implanted in pyrolytic graphite (PG) perpendicular to basal plates is removed after sputtering the layer slightly thicker than oxygen stopping zone (?2nm).

A. Airapetov; L. Begrambekov; S. Brémond; D. Douai; A. Kuzmin; Ya. Sadovsky; P. Shigin; S. Vergasov

2011-01-01

104

Reduction of outgassing rate by glow discharge cleaning  

SciTech Connect

The effectiveness of glow discharge cleaning (GDC) as a means of decreasing the pump-down time of vacuum systems was studied. We measured the outgassing rate of an electropolished stainless steel surface after it was exposed to glow discharges fueled by various gases (He, He/1%--3%H{sub 2}, He/1%--3%CH{sub 4}, H{sub 2}, Ar) following a standard 1 h of venting to ambient air. It is shown that He GDC is most effective in reduction of outgassing rate: a He GDC trial with a dose of 0.8 C/cm{sup 2} reduces the outgassing rate and subsequently the pump-down time by a factor of 13. For given glow discharge currents, the outgassing reduction factor is directly proportional to the glow discharge duration. The reduction of post-GDC outgassing is a result of enhanced desorption of H{sub 2}, CO, and CO{sub 2} by He GDC as observed by residual gas analysis during the discharge. The GDC results are consistent with our previously proposed diffusion models for water outgassing from metal surfaces. {copyright} {ital 1995} {ital American} {ital Vacuum} {ital Society}

Li, M.; Dylla, H.F. [Department of Physics, College of William and Mary, Williamsburg, Virginia 23185 (United States)]|[Continuous Electron Beam Accelerator Facility, Newport News, Virginia 23606 (United States)

1995-05-01

105

Reduction of outgassing rate by glow discharge cleaning  

SciTech Connect

The effectiveness of glow discharge cleaning (GDC) as a means of decreasing the pump-down time of vacuum systems was studied. We measured the outgassing rate of an electropolished stainless steel surface after it was exposed to glow discharges fueled by various gases (He, He/1%-3%H{sub 2}, He/1%-3%CH{sub 4}, H{sub 2}, Ar) following a standard 1 h of venting to ambient air. It is shown that He GDC is most effective in reduction of outgassing rate: a He GDC trial with a dose of 0.8 C/cm{sub 2} reduces the outgassing rate and subsequently the pump-down time by a factor of 13. For given glow discharge currents, the outgassing reduction factor is directly proportional to the glow discharge duration. The reduction of post-GDC outgassing is a result of enhanced desorption of H{sub 2}, CO, and CO{sub 2} by He GDC as observed by residual gas analysis during the discharge. The GDC results are consistent with our previously proposed diffusion models for water outgassing from metal surfaces.

Minxu Li; H. F. Dylla

1995-06-01

106

Glow discharge lamp: a light source for optical emission spectroscopy.  

National Technical Information Service (NTIS)

A glow discharge lamp based on a modified version of the Grimm design has been fabricated. Its utility as a radiation source for optical emmission spectrography by standardising a method for the analysis of low alloy steels using a set of certified standa...

K. S. Vishwanathan V. Srinivasan S. Nalini T. R. Mahalingam

1990-01-01

107

Glow discharge lamp: A light source for optical emission spectroscopy  

Microsoft Academic Search

A glow discharge lamp based on a modified version of the Grimm design has been fabricated. Its utility as a radiation source for optical emission spectrography by standardizing a method for the analysis of low alloy steels using a set of certified standards from DMRL, Hyderabad, has been demonstrated. A model has been proposed where the sputtering rates of different

K. S. Vishwanathan; V. Srinivasan; S. Nalini; T. R. Mahalingam

1990-01-01

108

Glow Discharge Induced Hydroxyl Radical Degradation of 2Naphthylamine  

Microsoft Academic Search

In an aqueous solution, normal electrolysis at high voltages switches over spontaneously to glow discharge electrolysis and gives rise to hydroxyl radical, hydrogen peroxide, and aqueous electron, as well as several other active species. Hydroxyl radical directly attacks organic contaminants to make them oxidized. In the present paper, 2-naphthylamine is eventually degraded into hydrogen carbonate and carbon dioxide. The degradation

Quanfang Lu; Jie Yu; Jinzhang Gao; Wu Yang

2005-01-01

109

Glow-discharge treatment for the modification of textiles  

Microsoft Academic Search

Increased requirements on the finishing of textile products like environmental protective production, new kinds of synthetic fibers and, above all, optimized surface properties, demand innovative production technics. The advantages of the glow discharge treatment have been well known in the laboratories for a long time. Nevertheless, this technique is hardly used in the textile industry. This can be due to

U. Vohrer; M. Müller; C. Oehr

1998-01-01

110

High electron density, atmospheric pressure air glow discharges  

Microsoft Academic Search

The pulsed electron heating effect has been studied on an atmospheric pressure air glow discharge. Application of a high voltage pulse causes a shift in the electron energy distribution function to higher energies. This causes a temporary increase of the ionization rate and consequently an increase of the electron density. The electron density after a 10 ns pulse application to

Frank Leipold; Abdel-Aleam H. Mohamed; Karl H. Schoenbach

2002-01-01

111

Metal Mesh Smear Sampling for Glow Discharge Analytical Spectroscopy  

SciTech Connect

Metal mesh smear sampling is being developed and evaluated for use in a number of glow discharge and other optical and mass spectrometric techniques. Sensitive elemental and isotopic analyses thus will be coupled with a convenient sampling scheme similar to one that is common for radiological surveys.

Shaw, R.W.; Barshick, C.M.; Ramsey, J.M.; Smith, D.H.

2000-06-01

112

OOPIC simulation of a cylindrical magnetron glow discharge  

Microsoft Academic Search

An Object Oriented Particle-in-Cell model of a plasma glow discharge in a cylindrical magnetron cleaning device has been developed to provide guidance in developing a novel in situ surface conditioning technique. The model tracks the trajectories of particles by solving the equations of motion and the electrostatic field equations. Simulation results are compared to experimental measurements obtained from a plasma

Mark Johnson; Fang Yee; Mick Cipollo; Krystyna Truszkowska; John Verboncoeur

2008-01-01

113

Benzene Dissociation in DC Atmospheric Pressure Air Glow Discharges  

NASA Astrophysics Data System (ADS)

By using a micro-hollow cathode discharge (MHCD) as an electron source to lower or eliminate the cathode fall voltage, a glow discharge could be operated in a dc atmospheric pressure air [1]. The effect of this glow discharge plasma on VOC (Volatile Organic Compound) remediation, particularly, benzene remediation, has been studied. A higher than 90 % destruction rate has been obtained by flowing a 300 ppm benzene/ dry air mixture through the plasma filament. The plasma is confined by a dielectric to a cross-section of 1 mm by 1.5 mm and extends over a depth of 0.8 mm. With a flow rate of 100 sccm, the residence time of the gas in the plasma column is 0.7 ms. A destruction efficiency of more than 0.5 L/kJ has been measured. The energy efficiency is 0.9 g/kWh which is comparable to that achieved by low pressure glow discharges in benzene/ noble gas mixtures [2]. References: [1] R. H. Stark and K. H. Schoenbach, "Direct Current Glow Discharges in Atmospheric Air," Appl. Phys. Lett. 89, 3568 (2001). [2] D. L. McCorkle, W. Ding, C. Ma and L. A. Pinnaduwage, "Dissociation of Benzene and Methylene Chloride Based on Enhanced Dissociative Electron Attachment to Highly Excited Molecules," J. Phys. D: Appl. Phys. 32, 46 (1999). Acknowledgments: This work is supported by the Air Force Office of Scientific Research.

Jiang, Chunqi; Stark, Robert H.; Schoenbach, Karl H.

2001-10-01

114

Demonstration of Separation Delay with Glow-Discharge Plasma Actuators.  

National Technical Information Service (NTIS)

Active flow control of boundary-layer separation using glow-discharge plasma actuators is studied experimentally. Separation is induced on a flat plate installed in a closed-circuit wind tunnel by a shaped insert on the opposite wall. The flow conditions ...

L. S. Hultgren D. E. Ashpis

2004-01-01

115

Investigation and application of hollow anode glow discharge ion source  

Microsoft Academic Search

In the present work, a new shape of a glow discharge ion source has been designed, fabricated and constructed at Accelerators and Ion Sources Department, Nuclear Research Center, Egyptian Atomic Energy Authority, Egypt. The discharge and output beam characteristics of the ion source at different operating gas pressures have been measured at the optimum distance between the anode and the

F. W. Abdelsalam; A. G. Helal; Y. B. Saddeek; M. M. Abdelrahman; B. A. Soliman

2010-01-01

116

Characteristics of atmospheric-pressure, radio-frequency glow discharges operated with argon added ethanol  

SciTech Connect

Rf, atmospheric-pressure glow discharge (APGD) plasmas with bare metal electrodes have promising prospects in the fields of plasma-aided etching, thin film deposition, disinfection and sterilization, etc. In this paper, the discharge characteristics are presented for the rf APGD plasmas generated with pure argon or argon-ethanol mixture as the plasma-forming gas and using water-cooled, bare copper electrodes. The experimental results show that the breakdown voltage can be reduced significantly when a small amount of ethanol is added into argon, probably due to the fact that the Penning ionization process is involved, and a pure {alpha}-mode discharge can be produced more easily with the help of ethanol. The uniformity of the rf APGDs of pure argon or argon-ethanol mixtures using bare metallic electrodes is identified with the aid of the intensified charge coupled device images.

Sun Wenting; Li Guo; Li Heping; Bao Chengyu; Wang Huabo; Zeng Shi; Gao Xing; Luo Huiying [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); School of Public Health and Family Medicine, Capital University of Medical Sciences, Beijing 100069 (China); Beijing Center for Diseases Control and Prevention, Beijing 100013 (China)

2007-06-15

117

Preparation of carbonitride films in the active and afterglow phases of a glow discharge  

NASA Astrophysics Data System (ADS)

The formation of carbonitride (C x N y ) films in the active and afterglow phases of a glow discharge in CH4-N2 mixtures (as well in these mixtures diluted with argon and helium) was studied experimentally. The dependences of the film growth rate on the discharge current and gas pressure are obtained. The composition (the N/C ratio) and IR absorption spectra of the films are determined. Measurements of the absorption spectra made it possible to identify bonds between C and N atoms. A novel method of carbonitride film deposition in the "double afterglow" mode was proposed. The use of this method appreciably increases the film deposition rate. Possible mechanisms of the formation and destruction of carbonitride films in the active and afterglow phases of the discharge are discussed.

Grigorian, G. M.; Kochetov, I. V.

2013-05-01

118

The back-diffusion effect of air on the discharge characteristics of atmospheric-pressure radio-frequency glow discharges using bare metal electrodes  

Microsoft Academic Search

Radio-frequency (RF), atmospheric-pressure glow discharge (APGD) plasmas using bare metal electrodes have promising prospects in the fields of plasma-aided etching, deposition, surface treatment, disinfection, sterilization, etc. In this paper, the discharge characteristics, including the breakdown voltage and the discharge voltage for sustaining a stable and uniform alpha mode discharge of the RF APGD plasmas are presented. The experiments are conducted

Wen-Ting Sun; Tian-Ran Liang; Hua-Bo Wang; He-Ping Li; Cheng-Yu Bao

2007-01-01

119

Sub-60 °C atmospheric helium-water plasma jets: modes, electron heating and downstream reaction chemistry  

NASA Astrophysics Data System (ADS)

For plasma treatment of many heat-labile materials (e.g. living tissues) that either are moist or contain a surface layer of liquid, it is desirable that the gas plasma is generated at atmospheric pressure for process convenience and with a gas temperature ideally no more than 60 °C for mitigating permanent damage to the integrity of the test material. This implies that the liquid-containing plasma needs to be of low dissipated electrical energy and that plasma treatment should be based largely on non-equilibrium reaction chemistry. In this paper, a class of sub-60 °C atmospheric helium-water plasma jets is studied in terms of their main physiochemical properties. It is shown that there are five distinct modes appearing in the sequence of, with increasing voltage, the first chaotic mode, the plasma bullet mode, the second chaotic mode, the abnormal glow mode and the non-thermal arc mode. Its chaotic modes may be sustained over a wide range of water vapour concentrations (0-2500 ppm). Compared with other liquid-containing plasmas, the He-H2O plasma jet operated below its non-thermal arc mode has several distinct advantages, namely very low energy consumption (2-10 µJ per pulse), sub-60 °C gas temperature, electron-modulated production of He, N2, N_2^+ , O*, H and OH(A-X), and low ozone production (0.1-0.4 ppm). These results provide a first attempt at the landscape of the physiochemical characteristics in atmospheric He-H2O plasma jets.

Liu, J. J.; Kong, M. G.

2011-08-01

120

Oscillations, Glow and Ignition in Carbon Monoxide Oxidation. I. Glow and Ignition in a Closed Reaction Vessel and the Effect of Added Hydrogen  

Microsoft Academic Search

Location of reproducible conditions for ignition, chemiluminescence (glow) and oscillatory behaviour in carbon monoxide oxidation is a classic unsolved problem. The present paper is primarily concerned with locating and distinguishing between the non-oscillatory instabilities (ignition and glow); subsequent parts will deal with oscillatory behaviour in closed and open systems and with the unifying mechanism. We use a clean, acid-washed, quartz

J. R. Bond; P. Gray; J. F. Griffiths

1981-01-01

121

Laser optogalvanic and fluorescence spectroscopy in glow discharge plasmas  

NASA Astrophysics Data System (ADS)

Diagnostic techniques based on laser optogalvanic spectroscopy and laser induced fluorescence are providing spatial and temporal maps of key quantities in glow discharge plasma. Such maps are particularly useful in studying the cathode region. This region is of fundamental interest because of the failure of the local field approximation, and of practical interest because of widespread use of glow discharges in plasma processing and other areas. Laser techniques are used to map space charge electric fields, charged particle densities, average energies of charged particles, flux densities of charged particles, excited atom densities, and other key quantities. These maps provide valuable insights into the dominant physical processes in the cathode region and provide a stringent test of numerical models. A more quantitative understanding of the cathode region is emerging from laser studies and from advanced modeling efforts.

Lawler, J. E.; den Hartog, E. A.

1990-05-01

122

Glow discharge electron impact ionization source for miniature mass spectrometers.  

PubMed

A glow discharge electron impact ionization (GDEI) source was developed for operation using air as the support gas. An alternative to the use of thermoemission from a resistively heated filament electron source for miniature mass spectrometers, the GDEI source is shown to have advantages of long lifetime under high-pressure operation and low power consumption. The GDEI source was characterized using our laboratory's handheld mass spectrometer, the Mini 10. The effects of the discharge voltage and pressure were investigated. Design considerations are illustrated with calculations. Performance is demonstrated in a set of experimental tests. The results show that the low power requirements, mechanical ruggedness, and quality of the data produced using the small glow discharge ion source make it well-suited for use with a portable handheld mass spectrometer. PMID:17441220

Gao, Liang; Song, Qingyu; Noll, Robert J; Duncan, Jason; Cooks, R Graham; Ouyang, Zheng

2007-05-01

123

Glow Discharge Induced Hydroxyl Radical Degradation of 2-Naphthylamine  

NASA Astrophysics Data System (ADS)

In an aqueous solution, normal electrolysis at high voltages switches over spontaneously to glow discharge electrolysis and gives rise to hydroxyl radical, hydrogen peroxide, and aqueous electron, as well as several other active species. Hydroxyl radical directly attacks organic contaminants to make them oxidized. In the present paper, 2-naphthylamine is eventually degraded into hydrogen carbonate and carbon dioxide. The degradation process is analyzed by using an Ultraviolet (UV) absorption spectrum, high-performance liquid chromatography (HPLC) and chemical oxygen demand (COD). It is demonstrated that 2-naphthylamine (c0 =30 mg·l-1) is completely converted within 2h at 30°C and 600 V by glow discharge electrolysis, and the degradation is strongly dependent upon the presence of ferrous ions. COD is ascended in the absence of ferrous ions and descended in the presence of them.

Lu, Quanfang; Yu, Jie; Gao, Jinzhang; Yang, Wu

2005-06-01

124

Direct-current glow discharges in atmospheric pressure air plasmas  

Microsoft Academic Search

Investigations have been conducted to experimentally validate the mechanisms of ionization in two-temperature atmospheric pressure air plasmas in which the electron temperature is elevated with respect to the gas temperature. To test a predicted S-shaped dependence of steady-state electron number density on the electron temperature and its macroscopic interpretation in terms of current density versus electric field, direct-current (dc) glow

Lan Yu; Christophe O. Laux; Denis M. Packan; Charles H. Kruger

2002-01-01

125

The use of dc glow discharges as undergraduate educational tools  

NASA Astrophysics Data System (ADS)

Plasmas have a beguiling way of getting students interested in physics. We argue that plasmas can and should be incorporated into the undergraduate curriculum as both demonstrations and advanced investigations of electromagnetism and quantum effects. We describe a device, based on a direct-current (dc) glow discharge tube, which allows for a number of experiments into topics such as electrical breakdown, spectroscopy, magnetism, and electron temperature.

Wissel, Stephanie A.; Zwicker, Andrew; Ross, Jerry; Gershman, Sophia

2013-09-01

126

Particle simulations of radio-frequency glow discharges  

Microsoft Academic Search

Particle-in-cell (PIC) simulations are used to study the structure of radio-frequency (RF) glow discharges in helium between parallel-plate electrodes. The authors have examined a range of conditions and report on a variety of observed phenomena. Comparisons to experiment and analytical models are made, when possible. The differences between discharges in which secondary electrons play a key role in sustaining the

M. Surendra; David B. Graves

1991-01-01

127

Positional glow curve simulation for thermoluminescent detector (TLD) system design  

NASA Astrophysics Data System (ADS)

Multi- and thin element dosimeters, variable heating rate schemes, and glow-curve analysis have been employed to improve environmental and personnel dosimetry using thermoluminescent detectors (TLDs). Detailed analysis of the effects of errors and optimization of techniques would be highly desirable. However, an understanding of the relationship between TL light production, light attenuation, and precise heating schemes is made difficult because of experimental challenges involved in measuring positional TL light production and temperature variations as a function of time. This work reports the development of a general-purpose computer code, thermoluminescent detector simulator, TLD-SIM, to simulate the heating of any TLD type using a variety of conventional and experimental heating methods including pulsed focused or unfocused lasers with Gaussian or uniform cross sections, planchet, hot gas, hot finger, optical, infrared, or electrical heating. TLD-SIM has been used to study the impact on the TL light production of varying the input parameters which include: detector composition, heat capacity, heat conductivity, physical size, and density; trapped electron density, the frequency factor of oscillation of electrons in the traps, and trap-conduction band potential energy difference; heating scheme source terms and heat transfer boundary conditions; and TL light scatter and attenuation coefficients. Temperature profiles and glow curves as a function of position time, as well as the corresponding temporally and//or spatially integrated glow values, may be plotted while varying any of the input parameters. Examples illustrating TLD system functions, including glow curve variability, will be presented. The flexible capabilities of TLD-SIM promises to enable improved TLD system design.

Branch, C. J.; Kearfott, K. J.

1999-02-01

128

Effect of glow discharge air plasma on grain crops seed  

SciTech Connect

Oat and barley seeds have been exposed to both continuous and pulsed glow discharge plasmas in air to investigate the effects on germination and sprout growth. Statistical analysis was used to evaluate the effect of plasma exposure on the percentage germination and length of sprout growth. A stimulating effect of plasma exposure was found together with a strong dependence on whether continuous or pulsed discharges were used.

Dubinov, A.E.; Lazarenko, E.M.; Selemir, V.D.

2000-02-01

129

The Use of DC Glow Discharges as Undergraduate Educational Tools  

SciTech Connect

Plasmas have a beguiling way of getting students excited and interested in physics. We argue that plasmas can and should be incorporated into the undergraduate curriculum as both demonstrations and advanced investigations of electromagnetism and quantum effects. Our device, based on a direct current (DC) glow discharge tube, allows for a number of experiments into topics such as electrical breakdown, spectroscopy, magnetism, and electron temperature.

Stephanie A. Wissel and Andrew Zwicker, Jerry Ross, and Sophia Gershman

2012-10-09

130

Glow discharge optical emission of plutonium and plutonium waste  

SciTech Connect

The application of glow discharges to the analysis of nonconducting materials such as glasses and ceramics is of great interest due to the number of advantages afforded by their direct solids capabilities. These types of samples, by their chemical nature, pose difficulties in dissolution for their subsequent analysis by common spectroscopic instrumental methods such as inductively coupled plasma atomic emission (ICP-AES). The ability of the glow discharge to sputter-atomize and excite solid nonconducting materials greatly reduces sample preparation time, cost, and complexity of an analysis. In comparison with x-ray spectroscopies, GD also provides the advantage of a relatively uniform sample atomization rate, resulting in a lowering of matrix effects. In a traditional direct current glow discharge (dc-GD), the material to be analyzed must first be ground and thoroughly mixed with a conductive host matrix and pressed into a solid pellet. Additionally, atmospheric gases which are often trapped in the sample upon pressing can degrade the quality of the plasma and obscure analytical results by reducing sputtering rates and affecting excitation conditions. Internal standardization has been carried out in both atomic absorption and emission dc-GD analyses in order to improve precision and accuracy which are affected by these problems.

Marcus, R.K. [Clemson Univ., SC (United States); Spencer, W.A. [Westinghouse Savannah River Company Savannah River Site, Aiken, SC (United States)

1995-11-09

131

Analysis of thermoluminescent glow peaks of zoisite under beta irradiations  

NASA Astrophysics Data System (ADS)

In this study, the thermoluminescence (TL) properties of natural crystal of zoisite were investigated after beta (90Sr) irradiation at room temperature (RT). Zoisite, of chemical formula Ca2Al3(SiO4)(Si2O7)O(OH), is found in Minas Gerais State, Brazil as natural mineral of silicate, member of the epidote group. The glow curve of a natural sample submitted to a heat treatment at 600 °C is composed of two broad peaks, centered at about 110-130 °C and another one at about 205-210 °C. A heating rate of 4 °C s-1 was used in the temperature range from RT to 300 °C. The additive dose, Tm-TSTOP thermal cleaning, initial rise, variable heating rate and computerized glow curve deconvolution methods have shown that the glow curve is a superposition of six peaks at 100, 130, 155, 175, 200 and 230 °C. The trapping parameters for the individual peaks have been calculated. The TL dose response of 130 and 200 °C peaks has a linear response. Zoisite is a candidate for a TL dosimeter because of its high sensitivity.

Ccallata, Henry Javier; Watanabe, Shigueo

2010-08-01

132

Analysis of thermoluminescent glow peaks of zoisite under beta irradiations  

SciTech Connect

In this study, the thermoluminescence (TL) properties of natural crystal of zoisite were investigated after beta ({sup 90}Sr) irradiation at room temperature (RT). Zoisite, of chemical formula Ca{sub 2}Al{sub 3}(SiO{sub 4})(Si{sub 2}O{sub 7})O(OH), is found in Minas Gerais State, Brazil as natural mineral of silicate, member of the epidote group. The glow curve of a natural sample submitted to a heat treatment at 600 deg. C is composed of two broad peaks, centered at about 110-130 deg. C and another one at about 205-210 deg. C. A heating rate of 4 deg. C s{sup -1} was used in the temperature range from RT to 300 deg. C. The additive dose, T{sub m}-T{sub STOP} thermal cleaning, initial rise, variable heating rate and computerized glow curve deconvolution methods have shown that the glow curve is a superposition of six peaks at 100, 130, 155, 175, 200 and 230 deg. C. The trapping parameters for the individual peaks have been calculated. The TL dose response of 130 and 200 deg. C peaks has a linear response. Zoisite is a candidate for a TL dosimeter because of its high sensitivity.

Ccallata, Henry Javier; Watanabe, Shigueo [Department of Nuclear Physics, Institute of Physics, University of Sao Paulo, CP: 66.318, Sao Paulo-SP 05315-970 (Brazil)

2010-08-04

133

Temporal and spatial formation of the glow discharge in neon filled diode at 4 mbar pressure  

Microsoft Academic Search

The results of the investigation of the glow discharge time and space development in the neon-filled diode at 4 mbar are presented. The glow is of the diffusion type with saturation current value 0.2 mA. The temporal development of current and light intensity of the 585.2-nm line (originated from the negative glow) emitted perpendicularly on the diode axis from different

M. K. Radovic; Cedomir A. Maluckov

2005-01-01

134

The Analysis of Main Dosimetric Glow Peaks in CaF2:Tm (TLD-300)  

NASA Astrophysics Data System (ADS)

The thermoluminescence properties of CaF2:Tm (TLD-300) are examined in detail after ?-irradiation at room temperature. The glow curve of the sample shows two main dosimetric glow peaks: P3 (at ~150°C) and P5 (at ~250°C). The additive dose, variable heating rate, computer glow curve deconvolution, peak shape and three points methods are used to evaluate the trapping parameters, namely the order of kinetics (b), activation energy (E) and frequency factor (s) associated with the dosimetric thermoluminescent glow peaks (P3 and P5) of CaF2:Tm (TLD-300) after different dose levels with ?-irradiation.

Vural, E. Kafadar; Metin, Bedir; A. Necmeddin, Yaz?c?; Tülin, Günal

2013-05-01

135

Influence of driving frequency on discharge modes in a dielectric-barrier discharge with multiple current pulses  

NASA Astrophysics Data System (ADS)

A one-dimensional self-consistent fluid model was employed to investigate the effect of the driving frequency on the discharge modes in atmospheric-pressure argon discharge with multiple current pulses. The discharge mode was discussed in detail not only at current peaks but also between two adjacent peaks. The simulation results show that different transitions between the Townsend and glow modes during the discharge take place with the driving frequency increased. A complicated transition from the Townsend mode, through glow, Townsend, and glow, and finally back to the Townsend one is found in the discharge with the driving frequency of 8 kHz. There is a tendency of transition from the Townsend to glow mode for the discharge both at the current peaks and troughs with the increasing frequency. The discharge in the half period can all along operate in the glow mode with the driving frequency high enough. This is resulted from the preservation of more electrons in the gas gap and acquisition of more electron energy from the swiftly varying electric field with the increase in driving frequency. Comparison of the spatial and temporal evolutions of the electron density at different driving frequencies indicates that the increment of the driving frequency allows the plasma chemistry to be enhanced. This electrical characteristic is important for the applications, such as surface treatment and biomedical sterilization.

Jiang, Weiman; Tang, Jie; Wang, Yishan; Zhao, Wei; Duan, Yixiang

2013-07-01

136

Further development of a gaseous ion source based on low-pressure hollow cathode glow  

NASA Astrophysics Data System (ADS)

The gaseous ion source based on a hollow cathode glow discharge with additional external injection of electron beam described in a previous publication has undergone further development. The direction of the source upgrade was to increase the total beam current and its density keeping the same broad beam cross section (about 100 cm2). With an operating gas pressure of 10-4 Torr, the maximum stable discharge current was as high as 40 A in 300 ?s (pulsed mode) and about 10 A (dc mode) without discharge gap arc breakdown. The total ion emission current exceeded 1 A in both cases. The geometry of the discharge gap was optimized, allowing improvement of the parameters of the device. The composition of the ion beam under various operating conditions of the discharge has been measured using the time-of-flight method. The electron beam injection into the hollow cathode of the ion source resulted in a reduction of the discharge voltage from the usual 500-600 V to 100 V or less. This lead to lower sputtering and as a result low contamination of the gaseous ion beam by metal fractions. Measurements showed 0.15% metal content instead of the typical several percent. The influence of the ion beam extraction on the discharge parameters was also examined.

Vizir, A. V.; Yushkov, G. Yu.; Oks, E. M.

2000-02-01

137

Measurement of voltage and current in continuous and pulsed RF and DC glow discharges  

NASA Astrophysics Data System (ADS)

Electrical measurements are an important tool for the characterisation of glow discharges and have proved to be useful for a variety of needs in fundamental studies and as control parameter. Therefore, extensive hardware developments and studies of I-U characteristics in continuous and pulsed, dc and rf modes have been made (Wilken et al. 2007) and will be presented together with new results. In continuous dc mode, the I-U curves are non-linear and may be characterised by a threshold voltage U_0 and saturation current I_max (both cathode material and pressure dependent). On the other hand P-U curves are to a large extent linear and very similar in the continuous rf mode (Hoffmann et al. 1998). The ionic part of time resolved I-U curves of rf discharges however shows almost a linear behaviour and the capacitive component is small. No saturation current exists. This led to the assumption that gas heating is responsible for the non-linearity between U and I in continuous dc discharges. Consistent with this assumption, a dependence of the U-I curves of pulsed discharges on the duty cycle was found. The comparison of the curves with those at low duty cycle (cold) led to a rough estimation of the gas temperature. Owing to the large changes of current in a very short time, the measurement of the electronic part of the U-I curve in rf mode is far more difficult. If conducting samples are analysed, this electronic part contains extra information. For pulsed rf discharges the hysteresis of electronic part increased with decreasing duty cycle (lower gas temperature). In a study of the effect of the addition of small amounts of H_2 to the Ar discharge gas similar changes in the electronic part of the U-I curve were observed whereas the ionic part was identical. Further investigation and cooperation with modelling groups is needed and planned to explain these results.

Hoffmann, V.; Efimova, V. V.; Voronov, M. V.; Smid, P.; Steers, E. B. M.; Eckert, J.

2008-07-01

138

A Study of Glow Discharge Polymerization as a Means of Preparing Composite Reverse Osmosis Membranes with Ultrathin Skin.  

National Technical Information Service (NTIS)

Polymer thin film formation by glow discharge in organic vapors (glow discharge polymerization, or plasma polymerization (PP) from a monomer (3.g., styrene) produces polymers which are considerably different from those formed from the same monomer by conv...

H. Yasuda

1982-01-01

139

Tooth - abnormal shape  

MedlinePLUS

Hutchinson incisors; Abnormal tooth shape; Peg teeth; Mulberry teeth; Conical teeth ... The appearance of normal teeth varies, especially the molars. Abnormally shaped teeth can result from many different conditions. Specific diseases can have a profound effect ...

140

Abnormal Head Position  

MedlinePLUS

... ocular problem. What are some of the ocular causes of an abnormal head position? Eye misalignment: Sometimes when ... asymmetry. What are some of the non-ocular causes of an abnormal head position? Congenital shortening of the ...

141

A Review on Chemical Effects in Aqueous Solution induced by Plasma with Glow Discharge  

NASA Astrophysics Data System (ADS)

Chemical effects in different aqueous solutions induced by plasma with glow discharge electrolysis (GDE) and contact glow discharge electrolysis (CGDE) are described in this paper. The experimental and discharge characteristics are also reviewed. These are followed by a discussion of their mechanisms of both anodic and cathodic CGDE..

Gao, Jin-zhang; Wang, Xiao-yan; Hu, Zhong-ai; Hou, Jing-guo; Lu, Quan-fang

2001-06-01

142

Atmospheric glow at a wavelength of 630 nm in a region of subauroral red arcs  

Microsoft Academic Search

The characteristics of atmospheric glow at 630 nm in a subauroral red arc region is investigated, assuming the glow energy source to be electromagnetic ion-cyclotron waves generated in the topside plasmasphere. Profiles of the volume emission rate of the atmosphere in the 140-1000 km height range are calculated. It is shown that, in contrast to nighttime conditions, two peaks can

Iu. V. Konikov; A. V. Pavlov

1990-01-01

143

Mass spectrometric study of rare earth oxide equilibria in the glow discharge  

Microsoft Academic Search

Glow discharge mass spectrometry has been used to study redox equilibria reactions of lanthanum and lanthanum oxide in an argon glow discharge. Introduction of the primary reagents of La and LaO is by sputter ejection from a cathodic sample. The plasma chemistry is greatly affected by oxidizing and reducing agents in the plasma, most prominent of which is residual water,

Yuan. Mei; W. W. Harrison

1993-01-01

144

Surface modification of PP under different electrodes of DC glow discharge and its physicochemical characteristics  

Microsoft Academic Search

The present investigation aims to study the wetting and physicochemical characteristics of Polypropylene (PP) sheet when exposed to a DC glow discharge through air across different electrodes such as copper, nickel and stainless steel at 13 W power level of DC glow discharge under an electrode size of 64 cm2. In order to estimate the extent of surface modification, the

S Bhowmik; P Jana; T. K Chaki; S Ray

2004-01-01

145

Prospective industrial applications of the one atmosphere uniform glow discharge plasma  

Microsoft Academic Search

The majority of industrial plasma processing is conducted with glow discharges at pressures below 10 torr. This tends to limit plasma processing applications to high value workpieces as a result of the high capital cost of vacuum systems and the production constraints of batch processing. It has long been recognized that glow discharges would play a much larger industrial role

J. Reece Roth

2004-01-01

146

Method of inducing differential etch rates in glow discharge produced amorphous silicon  

DOEpatents

A method of inducing differential etch rates in glow discharge produced amorphous silicon by heating a portion of the glow discharge produced amorphous silicon to a temperature of about 365.degree. C. higher than the deposition temperature prior to etching. The etch rate of the exposed amorphous silicon is less than the unheated amorphous silicon.

Staebler, David L. (Lawrenceville, NJ); Zanzucchi, Peter J. (Lawrenceville, NJ)

1980-01-01

147

Atmospheric Pressure Transient Micro Glow Discharge Driven by Burst Pulse Generator with Nonlinear Transmission Line  

Microsoft Academic Search

Summary form only given. One of the features of microplasmas is that atmospheric pressure glow discharges (APGDs), which attract growing attention in a variety of plasma applications, are easily obtained. We reported the dc-powered microplasma in air between nozzle and mesh electrodes with miniature gas flow. Although the stable glow discharge was generated, the input power was the order of

S. Ibuka; F. Furuya; K. Ogura; K. Yasuoka; S. Ishii

2007-01-01

148

Diamond film synthesis in high-alternating-current glow discharge  

NASA Astrophysics Data System (ADS)

Results of experiments with the deposition of polycrystalline diamond films onto silicon, titanium, and molybdenum substrates in a specially designed ac glow discharge system are presented. The phase composition and morphology of deposited films have been studied using the atomic force microscopy and X-ray diffraction techniques. It is established that the obtained diamond films possess high purity and degree of crystallinity. Inclusions of non-diamond carbon phases are absent. The rate of diamond film growth in the proposed system is 6-7 ?m/h.

Linnik, S. A.; Gaidaichuk, A. V.

2012-03-01

149

Decoloration of aqueous Brilliant Green by using glow discharge electrolysis.  

PubMed

This paper described a plasma degradation of Brilliant Green (BG) by glow discharge electrolysis. Various influencing factors such as the voltage, the distance between cathode and anode were examined. Ultraviolet (UV) absorption spectra, gas chromatogram-mass spectrum (GC-MS), and chemical oxygen demand (COD) were used to monitor the degradation process and to identify the major oxidation intermediates. It was confirmed that benzoic acid, 1,2,3,4,5,6-cyclohexanehexaol, and carboxylic acids (e.g., oxalic acid, succinic acid and hydroxyacetic acid) were produced in the degradation process. The results showed that BG rapidly underwent degradation and eventually mineralized into CO(2) and H(2)O. PMID:16603310

Gao, Jinzhang; Yu, Jie; Li, Yan; He, Xiaoyan; Bo, Lili; Pu, Lumei; Yang, Wu; Lu, Quanfang; Yang, Zhiming

2006-02-28

150

Dusty plasma structures in He-Kr DC glow discharge  

SciTech Connect

Ion drift in gas mixtures has certain properties that can be used to generate ion flows with desired characteristics. For example, when the field is strong, ion heating is significant, and there is a large difference in atomic weight between ions and atoms, the ion velocity distribution can be highly anisotropic. Ion distribution anisotropy, in turn, can cause a substantial change in properties of dust structures in plasmas. Experiments on dusty plasma structures in glow discharge in mixtures of light and heavy gases (helium and krypton) are performed, and results of numerical simulations of ion and electron drift in the mixture are presented.

Antipov, S. N., E-mail: antipov@ihed.ras.ru [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation); Vasil'ev, M. M., E-mail: mixxy@mail.ru; Maiorov, S. A., E-mail: mayorov_sa@mail.ru [Russian Academy of Sciences, Prokhorov General Physics Institute (Russian Federation); Petrov, O. F.; Fortov, V. E. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)

2011-03-15

151

Radial Distributions of Dusty Plasma Parameters in a Glow Discharge  

SciTech Connect

A self-consistent model for radial distributions of dusty plasma parameters in a DC glow discharge based on the non-local Boltzmann equation for EEDF, the drift-diffusion equation for ions, and the Poisson equation for self-consistent electric field is presented. The results show that for the case of high dust particles density when the recombination of electrons and ions exceeds the ionization near the tube axis, radial electron and ion fluxes change their direction toward the center of the tube, and the radial electric field is reversed.

Fedoseev, A. V. [Institute of Thermophysics SB RAS, Lavrentyev Ave., 1, Novosibirsk, 630090 (Russian Federation); Sukhinin, G. I. [Institute of Thermophysics SB RAS, Lavrentyev Ave., 1, Novosibirsk, 630090 (Russian Federation); Novosibirsk State University, Pirogova Str., 2, Novosibirsk, 630090 (Russian Federation)

2011-11-29

152

Diode laser excited optogalvanic spectroscopy of glow discharges  

SciTech Connect

The development of diode-laser-excited isotopically-selective optogalvanic spectroscopy (OGS) of uranium metal, oxide and fluoride in a glow discharge (GD) is presented. The technique is useful for determining isotopic ratios of {sup 235}U/({sup 235}U + {sup 238}U) in the above samples. The precision and accuracy of this determination is evaluated, and a study of experimental parameters pertaining to optimization of he measurement is discussed. Application of the GD-OGS to other f-transition elements is also described.

Barshick, C.M.; Shaw, R.W.; Post-Zwicker, A., Young, J.P.; Ramsey, J.M.

1996-10-01

153

NSTX Filament Preionization and Glow Discharge Cleaning Systems  

SciTech Connect

Initial NSTX GDC experiments were performed with one moveable anode and a biased filament preionization system that allowed D2 and He Glow Discharge breakdowns at the actual operating pressure, voltage and current. The biased filament system was also operated continuously during ohmic operations, and used to reduce volt-sec consumption for February 1999 plasma discharges up to 280 KA. An upgraded system has been installed with 2 fixed wall anodes and 3 biased filaments; 2 on the mid-plane and one in the divertor region; all separately controllable remotely using a PLC system. Recent applications include assisting in preionization for 800 KA plasma discharges.

H.W. Kugel, W. Blanchard, G. D'Amico, R. Gernhardt, T. Provost

1999-11-01

154

TiN Production in a Glow Discharge  

NASA Astrophysics Data System (ADS)

We have been studying direct current glow discharges aiming at the production of different paint of coatings on steel substrates. In a set of preliminary experiments, long lasting (hours) discharges performed in a Nitrogen atmosphere between a stell anode (holding the substrates) and a titanium cathode separated by a small gap (few mm) produced very thin coatings of the substrates whose colour depend on the parameter of (interelectrodes gap, gas pressure, discharge current and time duration). In some conditions, the coatings showed a golden colour, typical of the Nti compound. A discussion of the results is given.

Arango, P. J.; Devia, A.; Rojas, A. F.; Peńa, C. A.; Ortiz, J. A.; Restrepo, E.

155

Experiments Characterizing the X-Ray Emission from a Solid-State Cathode Using a High-Current Glow Discharge  

NASA Astrophysics Data System (ADS)

X-ray emission (with intensity up to 0.01 Gy/s) was recorded in research on a possible mechanism of initiating nuclear transmutation reactions in a solid-state cathode medium in glow discharge experiments. The experiments were carried using a glow discharge1 with deuterium and hydrogen (at pressures up to 10 Torr), and using various cathode metals (Al, Sc, Ti, Ni, Nb, Zr, Mo, Pd, Ta, W, Pt and Pb). The x-rays were recorded using thermoluminescent detectors, x-ray film, and scintillation detectors with photomultipliers. Two different modes of the emission were observed during these experiments: (1) Diffusion x-rays were observed as separate x-ray bursts (up to 105 bursts a second and up to 106 x-ray quanta in a burst) with an average x-rays energy (from measurements using thermoluminescent detectors) in the range of 1.3-1.8 keV. (2) X-rays as laser microbeams (up to 104 beams a second and up to 109 x-ray quanta in a burst). The emission of the x-ray laser beams occurred during the discharge, and within 100ms after turning off the discharge current. The results obtained constitute a direct experimental proof for the existence of excited metastable energy levels with energies in the range 1.2-5.0 keV, within the solid-state cathode sample.

Karabut, A. B.; Kolomeychenko, S. A.

2005-12-01

156

GCAFIT—A new tool for glow curve analysis in thermoluminescence nanodosimetry  

NASA Astrophysics Data System (ADS)

Glow curve analysis is widely used for dosimetric studies and applications. Therefore, a new computer program, GCAFIT, for deconvoluting first-order kinetics thermoluminescence (TL) glow curves and evaluating the activation energy for each glow peak in the glow curve has been developed using the MATLAB technical computing language. A non-linear function describing a single glow peak is fitted to experimental points using the Levenberg-Marquardt least-square method. The developed GCAFIT software was used to analyze the glow curves of TLD-100, TLD-600, and TLD-700 nanodosimeters. The activation energy E obtained by the developed GCAFIT software was compared with that obtained by the peak shape methods of Grossweiner, Lushchik, and Halperin-Braner. The frequency factor S for each glow peak was also calculated. The standard deviations are discussed in each case and compared with those of other investigators. The results show that GCAFIT is capable of accurately analyzing first-order TL glow curves. Unlike other software programs, the developed GCAFIT software does not require activation energy as an input datum; in contrast, activation energy for each glow peak is given in the output data. The resolution of the experimental glow curve influences the results obtained by the GCAFIT software; as the resolution increases, the results obtained by the GCAFIT software become more accurate. The values of activation energy obtained by the developed GCAFIT software a in good agreement with those obtained by the peak shape methods. The agreement with the Halperin-Braner and Lushchik methods is better than with that of Grossweiner. High E and S values for peak 5 were observed; we believe that these values are not real because peak 5 may in fact consist of two or three unresolved peaks. We therefore treated E and S for peak 5 as an effective activation energy, Eeff, and an effective frequency factor, Seff. The temperature value for peak 5 was also treated as an effective quantity, Tm eff.

Abd El-Hafez, A. I.; Yasin, M. N.; Sadek, A. M.

2011-05-01

157

Interaction of a surface glow discharge with a gas flow  

SciTech Connect

A surface glow discharge in a gas flow is of particular interest as a possible tool for controlling the flow past hypersonic aircrafts. Using a hydrodynamic model of glow discharge, two-dimensional calculations for a kilovolt surface discharge in nitrogen at a pressure of 0.5 Torr are carried out in a stationary gas, as well as in a flow with a velocity of 1000 m/s. The discharge structure and plasma parameters are investigated near a charged electrode. It is shown that the electron energy in a cathode layer reaches 250-300 eV. Discharge is sustained by secondary electron emission. The influence of a high-speed gas flow on the discharge is considered. It is shown that the cathode layer configuration is flow-resistant. The distributions of the electric field and electron energy, as well as the ionization rate profile in the cathode layer, do not change qualitatively under the action of the flow. The basic effect of the flow's influence is a sharp decrease in the region of the quasineutral plasma surrounding the cathode layer due to fast convective transport of ions.

Aleksandrov, A. L., E-mail: a_alex@itam.nsc.ru; Schweigert, I. V. [Russian Academy of Sciences, Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch (Russian Federation)

2010-05-15

158

Low-Frequency Barrier-Free Atmospheric Glow Discharges  

NASA Astrophysics Data System (ADS)

Atmospheric pressure glow discharges (APGD) are currently one of the most exciting areas in gas discharge research. At low frequencies from 1 - 100kHz, APGD generation has been achieved so far with at least one of their electrodes insulated with a dielectric barrier. Without the dielectric barrier, it is often necessary to use higher excitation frequency in the megahertz range to sustain stable operation of APGD. In this contribution, we report the observation of stable barrier-free APGD operation generated between two bare electrodes and at a low frequency between 20kHz and 260kHz. Visual appearance of barrier-free APGD is uniform and free of any obvious streamers. Measured discharge current and voltage traces are smooth and without sharp spikes associated with filamentary plasmas. Dissipated power density is less than 1W/cm3, thus further confirming that they are glow discharges. To understand their generation mechanisms, a one-dimensional hydrodynamic model is used to highlight a new APGD mechanism distinctively different from both atmospheric DBD and radio-frequency APGD. To the best of our knowledge, this is the first observation of low-frequency barrier-free APGD in the kilohertz range and the first evidence that dielectric coating is no longer essential for APGD generation at any frequency.

Shi, Jianjun; Deng, Xuetao; Kong, Michael

2004-09-01

159

COMPOSITION AND STRUCTURAL STUDIES OF STRONG GLOW DISCHARGE POLYMER COATINGS  

SciTech Connect

OAK A271 COMPOSITION AND STRUCTURAL STUDIES OF STRONG GLOW DISCHARGE POLYMER COATINGS. An investigation of the chemical composition and structure of strong glow discharge (GDP) polymer shells made for cryogenic experiments at OMEGA is described. The investigation was carried out using combustion and Fourier Transform Infrared Spectroscopy (FTIR) analysis. The strongest coatings were observed to have the lowest hydrogen content or hydrogen/carbon H/C ratio, whereas the weakest coatings had the highest hydrogen content or H/C ratio. Chemical composition results from combustion were used to complement FTIR analysis to determine the relative hydrogen content of as-fabricated coatings. Good agreement was observed between composition results obtained from combustion and FTIR analysis. FTIR analysis of coating structures showed the strongest coatings to have less terminal methyl groups and a more double bond or olefinic structure. Strong GDP coatings that were aged in air react more with oxygen and moisture than standard GDP coatings. In addition to a more olefinic structure, there may also be more free-radial sites present in strong GDP coatings, which leads to greater oxygen uptake.

CZECHOWICZ, DG; CASTILLO, ER; NIKROO, A

2002-04-01

160

Deconvolution and simulation of thermoluminescence glow curves with Mathcad.  

PubMed

The paper reports two quite general and user-friendly calculation codes (called TLD-MC and TLS-MC) for deconvolution and simulation, respectively, of thermoluminescence (TL) glow curves, which have been implemented using the well-known engineering computing software PTC Mathcad. An advantage of this commercial software is the flexibility and productivity in setting up tailored computations due to a natural math notation, an interactive calculation environment and the availability of advanced numerical methods. TLD-MC includes the majority of popular models used for TL glow-curve deconvolution (the user can easily implement additional models if necessary). The least-squares (Levenberg-Marquardt) optimisation of various analytical and even some non-analytical models is reasonably fast and the obtained figure-of-merit values are generally excellent. TLS-MC implements numerical solution of the original set of differential equations describing charge carrier dynamics involving arbitrary number of interactive electron and hole traps. The programs are freely available from the website http://www.physic.ut.ee/~kiisk/mcadapps.htm. PMID:23528325

Kiisk, V

2013-03-24

161

Shock wave interaction with pulsed glow discharge and afterglow plasmas  

NASA Astrophysics Data System (ADS)

Acoustic shock waves are launched by the spark-discharge of a high voltage capacitor in pulsed glow discharge and afterglow plasmas. The glow discharge section of the shock tube is switched on for a period of less than one second at a time, during which a shock wave is launched starting with a large delay between the plasma switch-on and the shock-launch. In the subsequent runs this delay is decremented in equal time intervals up to the plasma switch-on time. A photo acoustic deflection method sensitive to the density gradient of the shock wave is used to study the propagating shock structure and velocity in the igniting plasma. A similar set of measurements are also performed at the plasma switch-off, in which the delay time is incremented in equal time intervals from the plasma switch-off time until the afterglow plasma fully neutralizes itself into the room-temperature gas. Thus, complete time histories of the shock wave propagation in the igniting plasma, as well as in the afterglow plasma, are produced. In the igniting plasma, the changes in the shock-front velocity and dispersion are found to be a strong non-linear function of delay until a saturation point is reached. On the other hand, in the afterglow plasma the trend has been opposite and reversing towards the room temperature values. The observed shock wave properties in both igniting and afterglow plasmas correlate well with the inferred temperature changes in the two plasmas.

Podder, N. K.; Locascio, A. C.

2009-03-01

162

Microfabricated Glow Discharge Plasma (MFGDP) for Ambient Desorption/Ionization Mass Spectrometry.  

PubMed

A novel ambient ionization technique for mass spectrometry, microfabricated glow discharge plasma (MFGDP), is reported. This device is made of a millimeter-sized ceramic cavity with two platinum electrodes positioned face-to-face. He or Ar plasma can be generated by a direct current voltage of several hundreds of volts requiring a total power below 4 W. The thermal plume temperature of the He plasma was measured and found to be between 25 and 80 °C at a normal discharge current. Gaseous, liquid, creamy, and solid samples with molecular weights up to 1.5 kDa could be examined in both positive and negative mode, giving limits of detection (LOD) at or below the fg/mm(2) level. The relative standard deviation (RSD) of manual sampling ranged from 10% to ?20%, while correlation coefficients of the working curve (R(2)) are all above 0.98 with the addition of internal standards. The ionization mechanisms are examed via both optical and mass spectrometry. Due to the low temperature characteristics of the microplasma, nonthermal momentum desorption is considered to dominate the desorption process. PMID:24000803

Ding, Xuelu; Zhan, Xuefang; Yuan, Xin; Zhao, Zhongjun; Duan, Yixiang

2013-09-19

163

A new technique of radiation thermometry using a consumer digital camcorder: Observations of red glow at Aso volcano, Japan  

NASA Astrophysics Data System (ADS)

We newly developed a technique of radiation thermometry using a Sony'fs consumer digital camcorder. Our system is not only convenience and cost effective but with a better performance than previous infrared thermometers, particularly in the place like a crater of volcano where is abundant in gas. This is because our system uses the submicron wavelength band, in which radiation is less influenced by absorption of gas than in the thermal infrared wavelength (>3 mm). We carried out observations of red glow at Aso volcano and succeeded in measuring the temperature of about 800°C, which is much more acceptable than previously reported values of 200-400°C. When we measure the temperature of about 300-700°C and 600-900°C in the place where is abundant in gas, using the camcorder with the near-infrared and with the visible wavelength mode is better than the thermal infrared region, respectively.

Saito, T.; Sakai, S.; Iizawa, I.; Suda, E.; Umetani, K.; Kaneko, K.; Furukawa, Y.; Ohkura, T.

2005-02-01

164

Submillimeter-wave rotational spectra of DNC in highly excited vibrational states observed in an extended negative glow discharge  

NASA Astrophysics Data System (ADS)

Rotational transitions of DNC have been observed in the submillimeter-wave region in an extended negative glow discharge in a gas mixture of CD4 and N2. The dissociative recombination reaction of DCND+ with electrons is thought to be a dominant channel to produce DNC in highly excited vibrational states. The vibrational temperature for the ?3 vibrational mode is found to be about 4000 K, and the rotational lines in levels up to (0 0 8) are observed. The rotational and centrifugal distortion constants are determined for these states along with those for the (1 0 0) state. The measurement accuracy is high enough to determine some higher order vibration-rotation interaction constants.

Amano, T.

2011-05-01

165

Glow discharge cleaning of carbon fiber composite and stainless steel  

NASA Astrophysics Data System (ADS)

The paper experimentally investigates and analyses the features and mechanisms of both of oxygen removal by deuterium glow discharge from CFC, pyrolytic graphite and stainless steel subjected to irradiation in oxygen contaminated plasma. It is shown that oxygen implanted in pyrolytic graphite (PG) perpendicular to basal plates is removed after sputtering the layer slightly thicker than oxygen stopping zone (?2 nm). Fast deuterium ions penetrating into CFC during GDC transfer the trapped oxygen atoms into the bulk. Thus, much thicker surface layer has to be removed (500-1000 nm) for oxygen release.Irradiation of stainless steel in plasma leads to formation of a barrier layer with thickness (2-4 nm) equal, or slightly higher than stopping range of oxygen ions. The layer accumulates the main fraction of implanted oxygen and prevents its penetration into the bulk. After barrier layer sputtering oxygen spreads into the bulk. Parameters and conditions of optimum GDC are discussed.

Airapetov, A.; Begrambekov, L.; Brémond, S.; Douai, D.; Kuzmin, A.; Sadovsky, Ya.; Shigin, P.; Vergasov, S.

2011-08-01

166

Surface morphology of a glow discharge electrode in a solution  

NASA Astrophysics Data System (ADS)

This paper describes the surface morphology of a glow discharge electrode in a solution. In the experiments detailed in the paper, the effects of electrolysis time, solution temperature, voltage, electrolyte concentration, and surface area on the size of nanoparticles formed and their amount of nanoparticles produced were examined to study the surface morphologies of the electrodes. The results demonstrated that the amount of nanoparticles produced increased proportionally with the electrolysis time and current. When the voltages were below 140 V, surfaces with nanoparticles attached, called ``Particles'' type surfaces, were formed on the electrode. These surfaces changed and displayed ripples, turning into ``Ripple'' type surfaces, and the nanoparticle sizes increased with an increase in the amount of nanoparticles produced. In contrast, at voltages over 160 V, the surfaces of the electrodes were either ``Random'' or ``Hole'' type and the particle sizes were constant at different amount of nanoparticles produced.

Saito, Genki; Hosokai, Sou; Tsubota, Masakatsu; Akiyama, Tomohiro

2012-07-01

167

Efficient algorithm for simulating a multidimensional glow discharge  

SciTech Connect

A normal glow discharge in nitrogen between two infinite plane-parallel electrodes is simulated numerically in three dimensions in the drift-diffusion model. An algorithm is proposed that is based on solving the model equations by a hybrid of the sweep and relaxation methods and that combines a satisfactorily fast rate of convergence with the efficiency of individual iterations. The algorithm developed was used to carry out a three-dimensional simulation of a discharge in nitrogen at the pressures p = 5 and 1 Torr, the source voltage and ballast resistance being 2 kV and 300 k{Omega}, respectively. It was found that, at the pressure p = 1 Torr, the current density and charged particle densities change to a torioidal distribution in the anode region.

Petrusev, A. S.; Surzhikov, S. T. [Russian Academy of Sciences, Institute for Problems in Mechanics (Russian Federation)

2008-03-15

168

Xe isotopic fractionation in a cathodeless glow discharge  

NASA Astrophysics Data System (ADS)

Results are reported on the isotopic composition of Xe processed in cathodeless glow discharges in rarefied air at pressures of 20-40 microns Hg, in the presence of activated charcoal and in empty pyrex containers. Residual gas phase Xe and trapped Xe were found to be fractionated, with the trapped Xe fractionated up to 1 percent per amu. A model is presented for the fractionating process in which Xe ions are simultaneously implanted and sputtered from substrate material, with a mass dependence favoring retention of the heavy isotopes in the substrate. Results of the investigation show that plasma synthesis of carbonaceous material is unnecessary for producing Xe fractionations, and that the fractionations observed in previous synthesis experiments are probably due to implantation of ions into the synthesized material.

Bernatowicz, T. J.; Fahey, A. J.

1986-03-01

169

Hopf bifurcations in balance equations of glow discharges  

NASA Astrophysics Data System (ADS)

Starting from the hydrodynamic equations describing the positive column of glow discharges in inert gases, the instability of the axially homogeneous state is investigated. Dirichlet boundary conditions at the ends of the positive column are chosen. Stimulated by experiments, the influence of metastable atoms and of the outer circuit is taken into consideration by additional equations. Center manifold and normal form theories are used to characterize the codimension-one bifurcations. Depending on the current, the length of the positive column and the resistance of the outer circuit supercritical and subcritical Hopf bifurcations are found. The importance of the results with respect to the experiments on the ionization instability in a neon discharge is discussed.

Koch, B.-P.; Goepp, N.; Bruhn, B.

1997-08-01

170

Dust Waves Excited in a DC Glow Discharge Plasma  

SciTech Connect

We present a review of experimental studies to excite nonlinear dust waves in a dc glow discharge plasma. The experiments were performed in a vertically positioned glass tube filled with neon and the stratified glow discharge with cold electrodes was created inside it. Dust particles were injected into a plasma and formed ordered structures in the striations. The dust grains were illuminated with a laser sheet and the scattered light was registered with a high-speed digital videocamera with the frame rate of 1000 fps and spatial resolution of 20 {mu}m/pixel. We performed experiments with different techniques of the wave excitation. First, we used the gas-dynamic impact to move the dusty plasma structure with respect to their trap. In this case a large-amplitude wave with two compressional regions separated by a rarefaction was generated. The second wave excitation method was the application of an electromagnetic impulse to the dusty plasma structure. The impulse was created by the discharge of a high-voltage capacitor into a flat coil reeled around the discharge tube. The impulse of the axial magnetic field excited a perturbation. The perturbation had a character of discontinuity of the dust density and velocity. The perturbation was steepening and formed into a dust-acoustic shock. One more method of the wave excitation was developed that allowed to get two pulses. This gives us a possibility to investigate an interaction of waves excited in the dust component and a propagation of waves in a dusty plasma media with changeable dust density as well.

Torchinsky, V.M.; Naumkin, V.N.; Molotkov, V.I.; Fortov, V.E.; Petrov, O.F.; Khrapak, A.G.; Poustylnik, M.Y. [Institute for High Energy Densities, Russian Academy of Sciences, Moscow, 125412, Izhorskaya13/19 (Russian Federation)

2005-10-31

171

Dust Waves Excited in a DC Glow Discharge Plasma  

NASA Astrophysics Data System (ADS)

We present a review of experimental studies to excite nonlinear dust waves in a dc glow discharge plasma. The experiments were performed in a vertically positioned glass tube filled with neon and the stratified glow discharge with cold electrodes was created inside it. Dust particles were injected into a plasma and formed ordered structures in the striations. The dust grains were illuminated with a laser sheet and the scattered light was registered with a high-speed digital videocamera with the frame rate of 1000 fps and spatial resolution of 20 ?m/pixel. We performed experiments with different techniques of the wave excitation. First, we used the gas-dynamic impact to move the dusty plasma structure with respect to their trap. In this case a large-amplitude wave with two compressional regions separated by a rarefaction was generated. The second wave excitation method was the application of an electromagnetic impulse to the dusty plasma structure. The impulse was created by the discharge of a high-voltage capacitor into a flat coil reeled around the discharge tube. The impulse of the axial magnetic field excited a perturbation. The perturbation had a character of discontinuity of the dust density and velocity. The perturbation was steepening and formed into a dust-acoustic shock. One more method of the wave excitation was developed that allowed to get two pulses. This gives us a possibility to investigate an interaction of waves excited in the dust component and a propagation of waves in a dusty plasma media with changeable dust density as well.

Torchinsky, V. M.; Naumkin, V. N.; Molotkov, V. I.; Fortov, V. E.; Petrov, O. F.; Khrapak, A. G.; Poustylnik, M. Y.

2005-10-01

172

Morphological abnormalities among lampreys  

USGS Publications Warehouse

The experimental control of the sea lamprey (Petromyzon marinus) in the Great Lakes has required the collection of thousands of lampreys. Representatives of each life stage of the four species of the Lake Superior basin were examined for structural abnormalities. The most common aberration was the presence of additional tails. The accessory tails were always postanal and smaller than the normal tail. The point of origin varied; the extra tails occurred on dorsal, ventral, or lateral surfaces. Some of the extra tails were misshaped and curled, but others were normal in shape and pigment pattern. Other abnormalities in larval sea lampreys were malformed or twisted tails and bodies. The cause of the structural abnormalities is unknown. The presence of extra caudal fins could be genetically controlled, or be due to partial amputation or injury followed by abnormal regeneration. Few if any lampreys with structural abnormalities live to sexual maturity.

Manion, Patrick J.

1967-01-01

173

Glow auxiliary electrical discharge for CW high-power CO2 lasers  

NASA Astrophysics Data System (ADS)

A new discharge technique for DC glow auxiliary electrical discharge (GAED) lasers has been developed in order to realize efficient, stable and compact CW transverse-flow high-power CO2 lasers. The auxiliary discharge power source for GAED is common to that of the main discharge. The discharge technique and characteristics of GAED are described. The luminous region of the positive column with auxiliary discharge became wider and more uniform than that without auxiliary discharge. The limited glow discharge power (the discharge power for initiating unstable glow discharge) with auxiliary discharge was about 2.2 times that without auxiliary discharge. It was also found that the maximum value of glow discharge power was obtained when the CO2 gas mixture ratio was 2-4 percent.

Suzuki, Setsuo; Noda, Etsuo; Morimiya, Osami

1991-09-01

174

Glow Discharge as an Atomization and Ionization Device. Progress Report, May 1, 1980-February 1, 1981.  

National Technical Information Service (NTIS)

Glow discharge ion sources are discussed, including ion source design, the effect of magnetic fields on discharge operation, influence of magnetic fields on ion sampling, and the disc cathode source. (ERA citation 06:014921)

W. W. Harrison

1981-01-01

175

A simple method to record thermoluminescence glow-curves between 77 and 300 K  

NASA Astrophysics Data System (ADS)

In this work a simple method is suggested for recording thermoluminescence in the temperature region between 77 K (Liquid nitrogen temperature) and 300 K (environmental temperature). The method is based on an exponential heating scheme instead of linear heating of the sample. The experimental setup required is much simpler than that of conventional thermoluminescence readers. In the present work it was possible to measure thermoluminescence glow-curves of materials which are widely used in dosimetry, using a very simple setup. Specifically, we measured the thermoluminescence glow-curves of LiF:Mg,Ti, Al2O3:C and of different quartz samples, unfired and fired at very high temperatures. Furthermore, a glow-curve de-convolution analysis of the TL glow-curves of LiF:Mg,Ti and Al2O3:C is performed using newly developed analytical expressions describing a single TL peak obtained under an exponential heating scheme.

Kitis, G.

2011-05-01

176

Synthesis of Single-Walled Carbon Nanotubes in a Glow Discharge Fine Particle Plasma  

SciTech Connect

Carbon fine particles were synthesized being negatively charged and confined in a glow discharge plasma. The deposited fine particles were analyzed by Raman spectroscopy and transmission electron microscopy (TEM) and were confirmed to include single-walled carbon nanotubes.

Imazato, N.; Imano, M.; Hayashi, Y. [Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan)

2008-09-07

177

Features of the transverse discharge glow depending on the gas flow rate in a vortex chamber  

NASA Astrophysics Data System (ADS)

Experimentally observed features in the formation of glowing zones in gas discharge at various mass flow rates are qualitatively explained based on the numerical simulation of a turbulent swirling flow with a local source of heat release.

Zavershinskii, I. P.; Klimov, A. I.; Makaryan, V. G.; Molevich, N. E.; Moralev, I. A.; Porfir'ev, D. P.

2009-12-01

178

Liquid Sampling-Atmospheric Pressure Glow Discharge Ionization Source for Elemental Mass Spectrometry  

Microsoft Academic Search

A new, low power ionization source for elemental MS analysis of aqueous solutions is described. The liquid sampling-atmospheric pressure glow discharge (LSAPGD) operates by a process wherein the surface of the liquid emanating from a 75 m i.d. glass capillary acts as the cathode of the direct current glow discharge. Analytecontaining solutions at a flow rate of 100 L min-1

R. Kenneth Marcus; C. Derrick Quarles; Charles J. Barinaga; Anthony J. Carado; David W. Koppenaal

2011-01-01

179

Binary and ternary gas mixtures for use in glow discharge closing switches  

DOEpatents

Highly efficient binary and ternary gas mixtures for use in diffuse glow discharge closing switches are disclosed. The binary mixtures are combinations of helium or neon and selected perfluorides. The ternary mixtures are combinations of helium, neon, or argon, a selected perfluoride, and a small amount of gas that exhibits enhanced ionization characteristics. These mixtures are shown to be the optimum choices for use in diffuse glow discharge closing switches by virtue of the combined physio-electric properties of the mixture components.

Hunter, Scott R. (Oak Ridge, TN); Christophorou, Loucas G. (Oak Ridge, TN)

1990-01-01

180

Room temperature sterilization of surfaces and fabrics with a One Atmosphere Uniform Glow Discharge Plasma  

Microsoft Academic Search

  We report the results of an interdisciplinary collaboration formed to assess the sterilizing capabilities of the One Atmosphere\\u000a Uniform Glow Discharge Plasma (OAUGDP). This newly-invented source of glow discharge plasma (the fourth state of matter) is\\u000a capable of operating at atmospheric pressure in air and other gases, and of providing antimicrobial active species to surfaces\\u000a and workpieces at room temperature

K Kelly-Wintenberg; T C Montie; C Brickman; J R Roth; A K Carr; K Sorge; L C Wadsworth; P P Y Tsai

1998-01-01

181

Stability of atmospheric pressure glow discharge and application to carbon nanotube deposition  

Microsoft Academic Search

This paper describes carbon nanotube deposition using helium-based glow barrier discharge. Two important issues will be discussed: The stability of glow discharge and aligned growth of nanotube. Silicone substrate having 20 nm nickel film was secured on metallic bottom electrode where the temperature was elevated by 600C. In addition to CH4 or C2H2, the process gas also include hydrogen (

Tomohiro Nozaki; Ken Okazaki; Uwe Kortshagen; Joachim Heberlein

2003-01-01

182

An improved multi-anode contact glow discharge electrolysis reactor for dye discoloration  

Microsoft Academic Search

To promote treatment efficiency of organic pollutant, an improved multi-anode contact glow discharge reactor was developed for dye discoloration. This paper investigated how and what extent multi-anode contact glow discharge electrolysis (m-CGDE) could improve the discoloration efficiency of Acid Orange 7 (AO). I-V characteristic of m-CGDE was also studied in details. It was found that the critical voltage of m-CGDE

Xinglong Jin; Hongmei Zhang; Xiaoyan Wang; Minghua Zhou

183

Two-point method for kinetic analysis of a thermoluminescence glow peak  

NASA Astrophysics Data System (ADS)

We present a method for the estimation of defect (trap) physical parameters from thermoluminescence (TL) glow peaks. In this method, the order of kinetics b is determined using two values of TL intensity each of which corresponds to the same temperature (T-1) on two separate glow peaks of a phosphor. The two glow peaks are obtained from two aliquots of the phosphor irradiated to same dose but read out at different heating rates. The proposed method requires a minimum of only two data points in contrast to standard peak shape (PS) methods that require three points corresponding to three different temperatures on the same glow peak. Once the order of kinetics b is determined, the activation energy E is calculated by taking a second point (T-2) on any one of the two glow peaks. The values of b and E thus obtained are used to evaluate the frequency factor S'' and the number of trapped electrons before the heating begins n(o). The validity of the method was checked using two numerically generated glow peaks. For the two cases, the method reproduced the input values reasonably well. The method was also used to analyse two experimental glow peaks. The results obtained provide a reasonably good fit to the experimental data. The kinetic parameters calculated using the present technique are comparable to those calculated using PS and initial rise methods. Initial guesses can easily be obtained for E and S'' using the present technique when a glow curve is to be deconvoluted with a model consisting of many unknown parameters with E and S'' inclusive.

Ogundare, F. O.; Chithambo, M. L.

2006-05-01

184

Numerical analysis of two homogeneous discharge modes at atmospheric pressure with a self-consistent model  

SciTech Connect

Two homogeneous discharge modes, Townsend discharge and glow discharge, can be obtained in dielectric barrier discharges at atmospheric pressure when an external voltage with an appropriate frequency is applied to the electrodes. In this paper, a one-dimensional self-consistent model was used to investigate the transition and the difference in characteristics of these two modes. The simulation results showed that the spatiotemporal distributions of the electron temperature in the two discharge modes differed noticeably. In the glow discharge, the electron temperature in the cathode fall was several times higher than that in any of the other regions; in contrast, the electron temperature in the Townsend discharge was approximately spatially uniform. The electron energy distribution functions (EEDFs) at different locations in the discharge gap at the discharge current peaks were given and analyzed. In the glow discharge, the EEDF in the cathode fall region contained the largest percentage of high energy in all regions, and the majority of the electrons in the negative glow region possessed very low energy. However in the Townsend discharge, the EEDFs at different locations were similar to each other. In addition, both the discharge current density and the voltage drop on the discharge gas versus the applied voltage were also examined. It was found that when the applied voltage was over a critical value, the Townsend discharge turned into the glow discharge, the peak magnitude of the discharge current density increased abruptly. The maximum of the discharge current density was nearly a linear function of the applied voltage, while the voltage drop on the discharge gas was approximately a constant. Also, we found that there was a minimum of the applied voltage leading to the transition from the Townsend discharge to the glow discharge as the discharge gap spacing varied.

Wang Qi; Sun Jizhong; Wang Dezhen [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116023 (China)

2009-04-15

185

A MODULAR STEADY STATE GLOW DISCHARGE QUADRUPOLE MASS SPECTROMETER SYSTEM FOR THE AT-LINE ANALYSIS OF PLUTONIUM METAL  

SciTech Connect

Historically, glow discharge mass and optical spectrometric techniques have been used in industry for the characterization of processed metals, such as steels and other alloys. This technique is especially well suited for this type of product analysis because the glow discharge ionization source accommodates solid conducting samples with minimal or no sample preparation. This characteristic along with minimal matrix effect considerations makes the glow discharge source well suited for these types of applications.

R. STEINER; D. WAYNE

1998-12-01

186

Influence of the applied voltage shape on the barrier discharge operation modes in helium  

NASA Astrophysics Data System (ADS)

For the investigation of a barrier discharge (BD) operated in helium, a discharge cell configuration was used which allows an electrical characterization and simultaneous measurements of volume processes as well as the interaction of the BD with a dielectric surface. The emission development in the volume has been recorded spatio-temporally and spectrally resolved by the established cross-correlation spectroscopy (CCS) operating in the PPG mode. The phase resolved measurement (over one discharge period) of surface charges deposited on a BSO crystal was realized by the utilization of the electro-optic Pockels effect in combination with a high-speed camera. Depending on the gap distance, the dielectrics, and the shape of feeding voltage, the BD can operate either in the diffuse Townsend-like or glow-like mode. The emission is localized near the anode and cathode for the Townsend-like mode and glow-like mode, respectively. In small gaps (distance about 1 mm), a sinusoidal feeding voltage leads to the unusual Townsend-like mode in helium. But, a square wave voltage shape induces the glow-like mode, probably due to the fast rise and fall time of the applied voltage slopes. A sawtooth voltage generates both discharge modes over one period. The presented results show clearly the correlation of the emission development with electrical measurements, and deposited surface charge and transported charges.

Bogaczyk, Marc; Sretenovi?, Goran B.; Wagner, Hans-Erich

2013-10-01

187

Degradation of Anionic Dye Eosin by Glow Discharge Electrolysis Plasma  

NASA Astrophysics Data System (ADS)

This paper describes a novel method for the degradation of eosin by using glow discharge electrolysis (GDE). The effects of various parameters on the removal efficiency were studied. It was found that the eosin degradation could be raised considerably by increasing the applied voltage and the initial concentration, or by decreasing pH of the aqueous solution. Fe2+ ion had an evident accelerating effect on the eosin degradation. The degradation process of eosin obeyed a pseudo-first-order reaction. The relationship between the degradation rate constant k and the reaction temperature T could be expressed by Arrhenius equation with which the apparent activation energy Ea of 14.110 kJ. mol-1 and the pre-exponential factor ko of 2.065×10-1 min-1 were obtained, too. The determination of hydroxyl radical was carried out by using N,N-dimethyl-p-nitrosoaniline (RNO) as a scavenger. The results showed that the hydroxyl radical plays an important role in the degradation process.

Gao, Jinzhang; Ma, Dongping; Guo, Xiao; Wang, Aixiang; Fu, Yan; Wu, Jianlin; Yang, Wu

2008-08-01

188

Thermal mechanism of prepeak formation in Pulsed Glow Discharge  

NASA Astrophysics Data System (ADS)

A microsecond Pulsed Glow Discharge (?s PGD) in a Grimm-type source is characterized by the so-called ``prepeak,'' which is a spike in both electrical current and emission intensity at the leading edge of the discharge pulse. The prepeak is followed by synchronized vibrations of the current and the emission. To understand the nature of these phenomena, a microphone was inserted into the discharge chamber. Acoustical waves were detected and found to be in correlation with the measured vibrations. This points to a thermal mechanism for prepeak formation: the gas is heated in the leading edge of the discharge pulse and then expanded. To prove this suggestion, a Monte-Carlo based model was developed to simulate the evolution of Ar concentration, temperature, and flow in time and space. Potentially, the model could be used for gas simulations in a wide range of different applications. Here, the model is incorporated into an existing but modified model of the ?s PGD in a Grimm-type plasma excitation source. Results of the simulations confirm that the thermal mechanism is responsible for the formation of the electrical prepeak and the pressure waves.

Voronov, Maxim; Hoffmann, Volker; Steingrobe, Tobias; Buscher, Wolfgang; Engelhard, Carsten; Storey, Andrew; Ray, Steven; Hieftje, Gary

2012-10-01

189

Xenon doping of glow discharge polymer by ion implantation  

SciTech Connect

We demonstrate controlled doping of a glow discharge polymer by implantation with 500 keV Xe ions at room temperature. The Xe retention exhibits a threshold behavior, with a threshold dose of {approx}2 x 10{sup 14} cm{sup -2}. Doping is accompanied by irradiation-induced changes in the polymer composition, including gradual H loss and a more complex non-monotonic behavior of the O concentration. The matrix composition saturates at C{sub 0.77}H{sub 0.22}O{sub 0.01} for Xe doses above {approx}5 x 10{sup 14} cm{sup -2} and up to the maximum dose studied (5 x 10{sup 15} cm{sup -2}). The retention mechanism is attributed to the modification of the polymer from a chain-like to clustered ring structure. The dopant profile and the elemental composition of the implanted polymer exhibit good stability upon thermal annealing up to 305 deg. C.

Shin, Swanee J.; Kucheyev, Sergei O.; Orme, Christine A.; Hamza, Alex V. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Youngblood, Kelly P.; Nikroo, Abbas; Moreno, Kari A.; Chen, Bryan [General Atomics, San Diego, California 92186 (United States)

2012-05-01

190

Biological surface modification of titanium surfaces using glow discharge plasma.  

PubMed

To improve the biological activity of titanium, by using of glow discharge plasma (GDP), albumin-grafted titanium disk have been implemented and carefully studied. Titanium disks were pre-treated with GDP in an environment filled with argon and allylamine gas. Glutaraldehyde was used as a cross-linking agent for albumin grafting. Then, the surface of the albumin-grafted titanium was examined using scanning electron microscopy and X-ray photoelectron spectroscopy. In addition, the static water contact angles of the albumin-grafted titanium disks were measured using goniometry. To observe the effects of albumin adsorption on cell behavior, MG-63 osteoblast-like cells were cultured on the surface-modified titanium disks. Blood coagulation resistance of the modified titanium was monitored and compared to the control titanium disks. The results demonstrated that MG-63 osteoblast-like cells cultured on the albumin-grafted titanium disks expressed better-differentiated morphology compare to cells grown on the control disks. Furthermore, albumin-grafting treatment significantly improved the surface wettability of the titanium disks and resulted in a significantly negative effect on thrombus formation. Based on these results, it was believed that the GDP can potentially improve the biofunctionality of titanium surfaces. PMID:21286829

Huang, Haw-Ming; Hsieh, Sung-Chih; Teng, Nai-Chia; Feng, Sheng-Wei; Ou, Ken-Liang; Chang, Wei-Jen

2011-02-01

191

Shock Wave Propagation Measurements in Glow Discharge Plasmas  

NASA Astrophysics Data System (ADS)

Mach 1.5--2.2 shock waves are produced in argon over a range of pressures 3--15 Torr by a fast capacitor discharge (quarter period ?1/4 = 1.4 ?s). The shock waves are allowed to traverse through a glow discharge plasma inside the shock tube, where the deflections of the laser beams, caused by the density jump at the shock front, are recorded on a fast oscilloscope. An average shock wave velocity in plasma is determined from the time history of the laser deflection signals. Shock wave speeds in plasma are found to be dependent on the plasma discharge current. Shock wave speeds increase by 18% for the plasma at 3.6 Torr over a range of plasma discharge current I = 0--150 mA and by 46% for the plasma at 15 Torr over I = 7--150 mA. In addition, shock wave amplitudes are attenuated in plasma and show linear dependence on the shock wave speed or Mach number.

Podder, Nirmol K.; Tarasova, Anastasia V.; Wilson, Ralph B., IV

2006-10-01

192

Models of Abnormal Scarring  

PubMed Central

Keloids and hypertrophic scars are thick, raised dermal scars, caused by derailing of the normal scarring process. Extensive research on such abnormal scarring has been done; however, these being refractory disorders specific to humans, it has been difficult to establish a universal animal model. A wide variety of animal models have been used. These include the athymic mouse, rats, rabbits, and pigs. Although these models have provided valuable insight into abnormal scarring, there is currently still no ideal model. This paper reviews the models that have been developed.

Seo, Bommie F.; Lee, Jun Yong; Jung, Sung-No

2013-01-01

193

Effects of Cloud on Goddard Lidar Observatory for Wind (GLOW) Performance and Analysis of Associated Errors  

NASA Astrophysics Data System (ADS)

The Goddard Lidar Observatory for Wind (GLOW), a mobile direct detection Doppler LIDAR based on molecular backscattering for measurement of wind in the troposphere and lower stratosphere region of atmosphere is operated and its errors characterized. It was operated at Howard University Beltsville Center for Climate Observation System (BCCOS) side by side with other operating instruments: the NASA/Langely Research Center Validation Lidar (VALIDAR), Leosphere WLS70, and other standard wind sensing instruments. The performance of Goddard Lidar Observatory for Wind (GLOW) is presented for various optical thicknesses of cloud conditions. It was also compared to VALIDAR under various conditions. These conditions include clear and cloudy sky regions. The performance degradation due to the presence of cirrus clouds is quantified by comparing the wind speed error to cloud thickness. The cloud thickness is quantified in terms of aerosol backscatter ratio (ASR) and cloud optical depth (COD). ASR and COD are determined from Howard University Raman Lidar (HURL) operating at the same station as GLOW. The wind speed error of GLOW was correlated with COD and aerosol backscatter ratio (ASR) which are determined from HURL data. The correlation related in a weak linear relationship. Finally, the wind speed measurements of GLOW were corrected using the quantitative relation from the correlation relations. Using ASR reduced the GLOW wind error from 19% to 8% in a thin cirrus cloud and from 58% to 28% in a relatively thick cloud. After correcting for cloud induced error, the remaining error is due to shot noise and atmospheric variability. Shot-noise error is the statistical random error of backscattered photons detected by photon multiplier tube (PMT) can only be minimized by averaging large number of data recorded. The atmospheric backscatter measured by GLOW along its line-of-sight direction is also used to analyze error due to atmospheric variability within the volume of measurement. GLOW scans in five different directions (vertical and at elevation angles of 45° in north, south, east, and west) to generate wind profiles. The non-uniformity of the atmosphere in all scanning directions is a factor contributing to the measurement error of GLOW. The atmospheric variability in the scanning region leads to difference in the intensity of backscattered signals for scanning directions. Taking the ratio of the north (east) to south (west) and comparing the statistical differences lead to a weak linear relation between atmospheric variability and line-of-sights wind speed differences. This relation was used to make correction which reduced by about 50%.

Bacha, Tulu

194

Thermoluminescence systems with two or more glow peaks described by anomalous kinetic parameters  

SciTech Connect

The usual first and second order TL kinetic expressions are based on a number of assumptions, including the usually unstated assumption that charges released from one type of trap, giving rise to one glow peak, are not retrapped on other types of traps, associated with other glow peaks. Equations have been developed describing TL systems in which charges released from one type of trap may be retrapped in other types of traps. Called interactive kinetic equations, they are quite simple but have been studied by numerical methods. In particular, glow curves computed from the interactive kinetic equations have been regarded as data and analyzed by fitting them to the usual first and second order kinetic expressions. All of the anomalous features described above are reproduced. For example, usually the computed glow peaks are well fitted by the first and second order expressions over their upper 60 to 80% but not in the wings. This explains why the usual analysis methods, especially those utilizing peak temperature, full width, etc. appear to describe such peaks. Often unrealistic kinetic parameters are often obtained. Furthermore, the computed glow curves often reproduce the observed dependence on dose.

Levy, P.W.

1983-01-01

195

Electrocardiographic manifestations: electrolyte abnormalities  

Microsoft Academic Search

Because myocyte depolarization and repolarization depend on intra- and extracellular shifts in ion gradients, abnormal serum electrolyte levels can have profound effects on cardiac conduction and the electrocardiogram (EKG). Changes in extracellular potassium, calcium, and magnesium levels can change myocyte membrane potential gradients and alter the cardiac action potential. These changes can result in incidental findings on the 12-lead EKG

Deborah B Diercks; George M Shumaik; Richard A Harrigan; William J Brady; Theodore C Chan

2004-01-01

196

Abnormal Uterine Bleeding  

Microsoft Academic Search

Abnormal uterine bleeding is a common presenting symptom in the family practice setting. In women of childbearing age, a methodical history, physical examination, and laboratory evaluation may enable the physician to rule out causes such as pregnancy and pregnancy-related disorders, medications, iatro- genic causes, systemic conditions, and obvious genital tract pathology. Dysfunctional uterine bleeding (anovulatory or ovulatory) is diagnosed by

JANET R. ALBERS; SHARON K. HULL; ROBERT M. WESLEY

197

What is abnormal psychology?  

Microsoft Academic Search

Abnormal psychology is the scientific study of the mental pathology that underlies the symptomatology of psychiatric diseases. It is general when the symptoms studied are common to a number of diseases; and special, when the symptoms studied are idiopathic to particular diseases.

A. E. Davies

1931-01-01

198

Character and abnormal psychology  

Microsoft Academic Search

Character may be defined in terms of ethically effective organization of all the forces of an individual. Such a definition takes account of modern ethical conceptions and seems to express the fundamental interest of all students of abnormal psychology. It serves to distinguish character from other aspects of personality.

W. S. Taylor

1926-01-01

199

Pigment abnormalities in flatfish  

Microsoft Academic Search

Pigment abnormalities have been reported to occur on both sides of flatfish. Hypomelanosis or pseudo-albinism, characterized by white patches or areas devoid of normal pigmentation on the ocular surface of the skin, is common in both wild and hatchery reared flatfish. The blind side may display hypermelanosis in the form of dark spots, known as ambicoloration of the skin. The

Arietta Venizelos; Daniel D Benetti

1999-01-01

200

ABNORMALITY, NORMALITY AND HEALTH  

Microsoft Academic Search

Ideally, each participant in psychotherapy should be accepted as a unique individual with no reference to diagnosis. Most forms of psychotherapy are limited by assumptions about abnormality that focus on pathology while ignoring the potential for growth that exists in all. Effective psychotherapy requires respect for human complexity. Each person needs to be perceived as embodying a unique balance of

LUCIEN A. BUCK

1990-01-01

201

THE GLOW DURATION TIME INFLUENCE ON THE IONIZATION RATE DETECTED IN THE DIODES FILLED WITH NOBLE GASES ON mbar PRESSURES UDC 537.52; 533.9  

Microsoft Academic Search

The results of the glow current duration time (glowing-time) influence on the ionization rate detected in the gas filled diodes are presented. The electrical breakdown was detected as the minimal current impulse. After that diode glow from the minimal glowing-time (10-3 s), up to the maximal 103 s, which overlap the time of the stationary regime formation in the gas

Olivera M. Stepanovi?; Miodrag K. Radovi?; A. Maluckov

202

A computerized glow curve analysis (GCA) method for WinREMS thermoluminescent dosimeter data using MATLAB.  

PubMed

A computerized glow curve analysis (GCA) program for handling of thermoluminescence data originating from WinREMS is presented. The MATLAB program fits the glow peaks using the first-order kinetics model. Tested materials are LiF:Mg,Ti, CaF(2):Dy, CaF(2):Tm, CaF(2):Mn, LiF:Mg,Cu,P, and CaSO(4):Dy, with most having an average figure of merit (FOM) of 1.3% or less, with CaSO(4):Dy 2.2% or less. Output is a list of fit parameters, peak areas, and graphs for each fit, evaluating each glow curve in 1.5 s or less. PMID:21561783

Harvey, John A; Rodrigues, Miesher L; Kearfott, Kimberlee J

2011-05-06

203

Decomposition Characteristics of an Artificial Biogas in a Low-Pressure DC Glow Discharge  

NASA Astrophysics Data System (ADS)

The decomposition characteristics of an artificial biogas, which is a mixture of CH4, CO2 and H2S, using a low pressure DC glow discharge have been investigated. It is found that H2, CO, C2H2, H2O, CS2 and COS are produced from the artificial biogas in the glow discharge. About 65 % of hydrogen atoms in CH4 are converted into H2 at the input energy of 800 J, at which CH4 is completely decomposed, and the decomposition characteristics of the artificial biogas has little dependency on H2S additive. Farther, H2S has a tendency to be decomposed earlier than the other components of the artificial biogas. When the glow discharge is generated in the artificial biogas with H2S, some of carbon atoms are found to deposit on electrodes and the wall of a discharge chamber.

Itoh, Yasuhiro; Oshita, Takamasa; Satoh, Kohki; Itoh, Hidenori

204

Glow phenomenon and crystallization: Evidence that they are different events for hafnium-zirconium mixed oxides  

SciTech Connect

If hydrous zirconia is heated at a controlled rate, an exothermic event occurs at about 723 K. Several investigators attributed this to a 'glow phenomenon', while others termed this a 'crystallization' process. These two events occur at the same temperature (723 K) for zirconia. However, evidence is presented to show that crystallization and the glow phenomenon occur at different temperatures for hafnia and Hf/Zr mixed oxides. In the first step of the transformation, the amorphous material undergoes a crystallization process to yield small crystals which diffract X-rays and possess a high surface area. In the second transformation, these small crystals coalesce to form larger particles which contain multiple domains since the crystal size obtained from X-ray line broadening does not change significantly during the exothermic event. The present results demonstrate that crystallization and the exothermic events, commonly referred to as a glow phenomenon, may be two separate events.

Srinivasan, R.; Davis, B.H. (Univ. of Kentucky, Lexington (United States))

1993-03-15

205

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

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

206

Direct gas injection with glow-plug ignition. Final report, August 1986-July 1987  

SciTech Connect

The objective of this work was to show that direct natural gas injection with glow-plug-ignition assist offers potential for allowing natural gas engines to increase specific power output and thermal efficiency to levels comparable to diesel engines. These potential improvements result from changing the current homogeneous-charge, carburetted Otto-cycle gas engines to a direct gas injected diesel cycle. Tests were conducted on a 5.4-inch-bore single cylinder engine utilizing direct natural gas injection with glow-plug ignition assist. The results show that direct natural gas injection with glow-plug ignition assist can provide natural gas engines with specific power output and thermal efficiency (without gas compressor) equal to diesel engines.

Richards, B.G.

1987-08-01

207

Calculation of rate constants for asymmetric charge transfer, and their effect on relative sensitivity factors in glow discharge mass spectrometry  

Microsoft Academic Search

For this paper, we have calculated the rate coefficients for asymmetric charge transfer between Ar+ ions and all elements of interest in analytical glow discharges, based on a semi-classical approach. These values were then used to make predictions on the relative sensitivity factors (RSFs) in glow discharge mass spectrometry (GDMS) (VG9000 discharge cell) for various elements. The RSFs were calculated

Annemie Bogaerts; Krassimir A. Temelkov; Nikolay K. Vuchkov; Renaat Gijbels

2007-01-01

208

Binary and ternary gas mixtures with temperature enhanced diffuse glow discharge characteristics for use in closing switches  

DOEpatents

An improvement to the gas mixture used in diffuse glow discharge closing switches is disclosed which includes binary and ternary gas mixtures which are formulated to exhibit decreasing electron attachment with increasing temperature. This increases the efficiency of the conductance of the glow discharge and further inhibits the formation of an arc. 11 figs.

Christophorou, L.G.; Hunter, S.R.

1990-06-26

209

Binary and ternary gas mixtures with temperature enhanced diffuse glow discharge characteristics for use in closing switches  

DOEpatents

An improvement to the gas mixture used in diffuse glow discharge closing switches is disclosed which includes binary and ternary gas mixtures which are formulated to exhibit decreasing electron attachment with increasing temperature. This increases the efficiency of the conductance of the glow discharge and further inhibits the formation of an arc.

Christophorou, Loucas G. (Oak Ridge, TN); Hunter, Scott R. (Oak Ridge, TN)

1990-01-01

210

FAST TRACK COMMUNICATION: On the regime transitions during the formation of an atmospheric pressure dielectric barrier glow discharge  

Microsoft Academic Search

The atmospheric pressure dielectric barrier discharge in helium is a pulsed discharge in nature. If during the electrical current pulse a glow discharge is reached, then this pulse will last only a few microseconds in operating periods of sinusoidal voltage with lengths of about 10 to 100 µs. In this paper we demonstrate that right before a glow discharge is

T. Martens; W. J. M. Brok; J. van Dijk; A. Bogaerts

2009-01-01

211

The mode of mitochondrial degeneration in gliomas  

Microsoft Academic Search

Summary Morphologically abnormal mitochondria from human glial tumours are described. For each tumour both the appearances of the mitochondria, and the subsequent mode of degeneration and formation of osmiophilic pigment is characteristic.

C. S. Foster; P. E. Spoerri; P. Glees; O. Spoerri

1978-01-01

212

Binary and ternary gas mixtures for use in glow discharge closing switches  

DOEpatents

Highly efficient binary and ternary gas mixtures for use in diffuse glow discharge closing switches are disclosed. The binary mixtures are combinations of helium or neon and selected perfluorides. The ternary mixtures are combinations of helium, neon, or argon, a selected perfluoride, and a small amount of gas that exhibits enhanced ionization characteristics. These mixtures are shown to be the optimum choices for use in diffuse glow discharge closing switches by virtue if the combines physio-electric properties of the mixture components. 9 figs.

Hunter, S.R.; Christophorou, L.G.

1988-04-27

213

Liver abnormalities in pregnancy.  

PubMed

Abnormalities of liver function (notably rise in alkaline phosphatase and fall in serum albumin) are common in normal pregnancy, whereas rise in serum bilirubin and aminotransferase suggest either exacerbation of underlying pre-existing liver disease, liver disease related to pregnancy or liver disease unrelated to pregnancy. Pregnant women appear to have a worse outcome when infected with Hepatitis E virus. Liver diseases associated with pregnancy include abnormalities associated hyperemesis gravidarum, acute fatty liver disease, pre-eclampsia, cholestasis of pregnancy and HELLP syndrome. Prompt investigation and diagnosis is important in ensuring a successful maternal and foetal outcome. In general, prompt delivery is the treatment of choice for acute fatty liver, pre-eclampsia and HELLP syndrome and ursodeoxycholic acid is used for cholestasis of pregnancy although it is not licenced for this indication. PMID:24090943

Than, Nwe Ni; Neuberger, James

2013-08-01

214

Chromosome abnormalities in glioma  

SciTech Connect

Cytogenetic studies were performed in 25 patients with gliomas. An interesting finding was a seemingly identical abnormality, an extra band on the tip of the short arm of chromosome 1, add(1)(p36), in two cases. The abnormality was present in all cells from a patient with a glioblastoma and in 27% of the tumor cells from a patient with a recurrent irradiated anaplastic astrocytoma; in the latter case, 7 unrelated abnormal clones were identified except 4 of those clones shared a common change, -Y. Three similar cases have been described previously. In a patient with pleomorphic astrocytoma, the band 1q42 in both homologues of chromosome 1 was involved in two different rearrangements. A review of the literature revealed that deletion of the long arm of chromosome 1 including 1q42 often occurs in glioma. This may indicate a possible tumor suppressor gene in this region. Cytogenetic follow-up studies were carried out in two patients and emergence of unrelated clones were noted in both. A total of 124 clonal breakpoints were identified in the 25 patients. The breakpoints which occurred three times or more were: 1p36, 1p22, 1q21, 1q25, 3q21, 7q32, 8q22, 9q22, 16q22, and 22q13.

Li, Y.S.; Ramsay, D.A.; Fan, Y.S. [Victoria Hospital, London, Ontario (Canada)] [and others

1994-09-01

215

EUVE observations of the helium glow: Interstellar and solar parameters  

NASA Astrophysics Data System (ADS)

We present new observations of the diffuse He I 58.4 nm background recorded in 1998 and 2000 by the Extreme Ultraviolet Explorer (EUVE). This emission is due to resonant scattering of the solar EUV radiation by interstellar and geocoronal helium. Depending on the geometry and relative velocity, a fraction of the interstellar helium glow can be absorbed by the line-of-sight geocoronal gas. The new results are combined with measurements obtained in 1992-93 and previously analyzed by Flynn et al. (\\cite{Flynn1998}). A kinetic model of the helium flow is now used to analyze the data and reproduce the absorption features due to geocoronal helium. This allows a precise determination of the interstellar flow bulk velocity vector. A model that includes both photoionization and electron impact ionization was fit to the data set. New constraints on the interstellar helium flow temperature and density, as well as on the solar 58.4 nm line width are obtained. The interstellar helium velocity vector parameters, ? = 74.7 ± 0.5 °, ? = -5.7 ± 0.5 °, VHe= 24.5 ± 2 km s-1, are found to be in good agreement with those derived from particle measurements. Using the solar He I 58.4 nm flux and photoionization rate proxies of McMullin et al. (2003), the neutral helium density and temperature derived from the Long Wavelength Spectrometer data is nHe = 0.013 ± 0.003 cm-3, and THe = 6500 ± 2000o respectively, again in good agreement with particle data. However, the width of the downwind cone when scanned across the latitudnal direction tends to be fit better with higher He temperatures, which might indicated latitude anisotropies in the He ionization that we have not included in our models. The solar He I 58.4 nm Doppler width, ? wD, is found to be =0.0074 nm, (or 38 ± 3 km s-1) in 1992-1993, i.e. near solar maximum, and ? wD= 0.0087 nm (45 ± 3 km s-1) in 1998, after solar minimum, in agreement with SOHO SUMER and CDS results, although again, the 1998 fits near solar minimum might suffer from latitudinal anisotropies.

Vallerga, J.; Lallement, R.; Lemoine, M.; Dalaudier, F.; McMullin, D.

2004-11-01

216

[Molecular abnormalities in lymphomas].  

PubMed

Numerous molecular abnormalities have been described in lymphomas. They are of diagnostic and prognostic value and are taken into account for the WHO classification of these tumors. They also shed some light on the underlying molecular mechanisms involved in lymphomas. Overall, four types of molecular abnormalities are involved: mutations, translocations, amplifications and deletions of tumor suppressor genes. Several techniques are available to detect these molecular anomalies: conventional cytogenetic analysis, multicolor FISH, CGH array or gene expression profiling using DNA microarrays. In some lymphomas, genetic abnormalities are responsible for the expression of an abnormal protein (e.g. tyrosine-kinase, transcription factor) detectable by immunohistochemistry. In the present review, molecular abnormalities observed in the most frequent B, T or NK cell lymphomas are discussed. In the broad spectrum of diffuse large B-cell lymphomas microarray analysis shows mostly two subgroups of tumors, one with gene expression signature corresponding to germinal center B-cell-like (GCB: CD10+, BCL6 [B-Cell Lymphoma 6]+, centerine+, MUM1-) and a subgroup expressing an activated B-cell-like signature (ABC: CD10-, BCL6-, centerine-, MUM1+). Among other B-cell lymphomas with well characterized molecular abnormalies are follicular lymphoma (BCL2 deregulation), MALT lymphoma (Mucosa Associated Lymphoid Tissue) [API2-MALT1 (mucosa-associated-lymphoid-tissue-lymphoma-translocation-gene1) fusion protein or deregulation BCL10, MALT1, FOXP1. MALT1 transcription factors], mantle cell lymphoma (cycline D1 [CCND1] overexpression) and Burkitt lymphoma (c-Myc expression). Except for ALK (anaplastic lymphoma kinase)-positive anaplastic large cell lymphoma, well characterized molecular anomalies are rare in lymphomas developed from T or NK cells. Peripheral T cell lymphomas not otherwise specified are a heterogeneous group of tumors with frequent but not recurrent molecular abnormalities. Gene profiling analysis shows that the expression of several genes is deregulated including PDGFRA (platelet-derived growth factor receptor) gene, encoding a receptor with tyrosine kinase activity. In angio-immunoblastic T-cell lymphomas molecular abnormalities are found in follicular helper T-cell (TFH) that express some distinctive markers such as CD10, PD-1, CXCR5 and the CXCL13 chemokine. ALK-positive anaplastic large cell lymphoma is a paradigme of T-cell lymphoma since it is associated with an X-ALK oncogenic fusion protein due to a translocation involving ALK gene at 2p23. ALK tyrosine kinase activates downstream pathways (Stat3/5b, Src kinases, PLC?, PI3 kinase) implicated in lymphomagenesis, proliferation and protection against apoptosis. Specific ALK inhibitors are currently in clinical evaluation. Lastly several lymphomas are associated with infectious agents that play a direct (EB virus, HTLV1) or indirect role (e.g. Helicobacter pylori in MALT lymphoma) in lymphomagenesis. PMID:21084243

Delsol, G

2010-11-01

217

Neurodevelopmental Abnormalities in ADHD  

PubMed Central

Structural and functional imaging studies in subjects with attention deficit hyperactivity disorder (ADHD) are reviewed with the goal of gleaning information about neurodevelopmental abnormalities characterizing the disorder. Structural imaging studies, particularly those with longitudinal designs, suggest that brain maturation is delayed by a few years in ADHD. However, a maturational delay model alone is incomplete: alternate courses are suggested by differences associated with phenotypic factors, such as symptom remission/persistence and exposure to stimulant treatment. Findings from functional imaging studies point to multiple loci of abnormalities that are not limited to frontal–striatal circuitry, which is important for executive and motivational function, but also include parietal, temporal and motor cortices, and the cerebellum. However, a definitive conclusion about maturational delays or alternate trajectories cannot be drawn from this work as activation patterns are influenced by task-specific factors that may induce variable performance levels and strategies across development. In addition, no studies have implemented cross-sectional or longitudinal designs, without which the developmental origin of differences in activation cannot be inferred. Thus, current task-evoked functional imaging provides information about dynamic or state-dependent differences rather than fixed or trait-related differences. In the future, task-free functional imaging holds promise for revealing neurodevelopmental information that is minimally influenced by performance/strategic differences. Further, studies using longitudinal designs that identify sources of phenotypic heterogeneity in brain maturation and characterize the relationship between brain function and underlying structural properties are needed to provide a comprehensive view of neurodevelopmental abnormalities in ADHD.

Vaidya, Chandan J.

2012-01-01

218

A simulation of electron motion in the cathode sheath region of a glow discharge in helium  

Microsoft Academic Search

Electron motion in the cathode sheath region of a glow discharge in helium has been simulated using a one-dimensional computer model. Distribution functions for the electron flux across the cathode sheath have been calculated for fourteen values of the cathode fall between 150 and 1700 V. Macroscopic variables including the Townsend ionisation coefficient, multiplication coefficient and mean electron energy have

R. J. Carman; A. Maitland

1987-01-01

219

Effects of norms, warm-glow and time use on household recycling  

Microsoft Academic Search

The aim of this paper is to quantify the relative importance of motivations based on warm-glow, social and moral norms and cost of time used recycling on household recycling efforts. We also test for crowding-out of intrinsic motivations when recycling is perceived as mandatory. We find that the most important variable increasing household recycling efforts is agreeing that recycling is

Bente Halvorsen

2004-01-01

220

Spatial concentrations of silicon atoms by laser-induced fluorescence in a silane glow discharge  

Microsoft Academic Search

A capacitively coupled, rf glow discharge of silane in argon was studied to determine the spatial concentration of silicon atoms. Laser-induced fluorescence was used to determine the ground state concentration profiles. The fluorescence profiles clearly show the sharp boundaries of the sheath regions. These profiles were much more sensitive to plasma chemistry changes than profiles obtained from plasma emission. Experiments

R. M. Roth; K. G. Spears; G. Wong

1984-01-01

221

Effects of Dielectric Barriers in Radio-Frequency Atmospheric Glow Discharges  

Microsoft Academic Search

This paper reports the effects of introducing dielectric barriers to radio-frequency (RF) atmospheric pressure glow discharges (APGD) that have hitherto employed bare electrodes. The resulting atmospheric RF dielectric barrier discharges (DBD) are experimentally shown to retain their large volume without constriction at very large currents, well above the maximum current at which conventional RF APGD with bare electrodes can maintain

Jianjun J. Shi; Dawei W. Liu; Michael G. Kong

2007-01-01

222

Quartz crystal microbalance simulation of the directionality of Si etching in CF 4 glow discharges  

Microsoft Academic Search

Two quartz crystal microbalances have been mounted in a planar rf discharge system in such a way that the potential of the microbalances with respect to the glow discharge can be varied. This apparatus allows a rapid simulation of the etching directionality that can be expected in real pattern transfer situations in that operating one microbalance at ground and one

Natasha C. Us; R. W. Sadowski; J. W. Coburn

1986-01-01

223

Plasma Processing with a One Atmosphere Uniform Glow Discharge Plasma (OAUGDP)  

NASA Astrophysics Data System (ADS)

The vast majority of all industrial plasma processing is conducted with glow discharges at pressures below 10 torr. This has limited applications to high value workpieces as a result of the large capital cost of vacuum systems and the production constraints of batch processing. It has long been recognized that glow discharges would play a much larger industrial role if they could be operated at one atmosphere. The One Atmosphere Uniform Glow Discharge Plasma (OAUGDP) has been developed at the University of Tennessee Plasma Sciences Laboratory. The OAUGDP is non-thermal RF plasma with the time-resolved characteristics of a classical low pressure DC normal glow discharge. An interdisciplinary team was formed to conduct exploratory investigations of the physics and applications of the OAUGDP. This team includes collaborators from the UTK Textiles and Nonwovens Development Center (TANDEC) and the Departments of Electrical and Computer Engineering, Microbiology, Food Science and Technology, and Mechanical and Aerospace Engineering and Engineering Science. Exploratory tests were conducted on a variety of potential plasma processing and other applications. These include the use of OAUGDP to sterilize medical and dental equipment and air filters; diesel soot removal; plasma aerodynamic effects; electrohydrodynamic (EDH) flow control of the neutral working gas; increasing the surface energy of materials; increasing the wettability and wickability of fabrics; and plasma deposition and directional etching. A general overview of these topics will be presented.

Reece Roth, J.

2000-10-01

224

Crystalline structures of strongly coupled dusty plasmas in dc glow discharge strata  

Microsoft Academic Search

Strongly coupled dusty plasmas are formed by suspending micron-sized dust particles in strata of a dc glow neon discharge. We have observed for the first time an ordered structure of the negatively charged particles trapped in the strata region. Image analysis reveals the crystalline structure, which is consistent with a large value of the Coulomb coupling parameter.

Vladimir E. Fortov; Anatoli P. Nefedov; Vladimir M. Torchinsky; Vladimir I. Molotkov; Oleg F. Petrov; Alex A. Samarian; Andrew M. Lipaev; Alexei G. Khrapak

1997-01-01

225

Isotopic abundance measurements on solid nuclear-type samples by glow discharge mass spectrometry  

Microsoft Academic Search

A double-focusing Glow Discharge Mass Spectrometer (GDMS) installed in a glovebox for nuclear sample screening has been employed for isotopic measurements. Isotopic compositions of zirconium, silicon, lithium, boron, uranium and plutonium which are elements of nuclear concern have been determined. Interferences arising from the matrix sample and the discharge gas (Ar) for each of these elements are discussed. The GDMS

Maria Betti; Gert Rasmussen; Lothar Koch

1996-01-01

226

Polycrystalline diamond synthesis by means of high power pulsed plasma glow discharge CVD  

Microsoft Academic Search

A pulsed glow discharge reactor for chemical vapour deposition of high quality diamond films is presented. The Raman quality and the morphology of the diamond films exhibit a strong dependence on the discharge pulse shape. This result is explained with a simple model involving the average current density j0 and the average squared amplitude of the pulse ??j2? as relevant

S. Sciortino; S. Lagomarsino; F. Pieralli; E. Borchi; E. Galvanetto

2002-01-01

227

Distribution function and potential in the cathode region of a glow discharge  

Microsoft Academic Search

In view of the minor role played by ionization in the cathode dark space of a glow discharge, the ion distribution function and the potential profile must be determined by simultaneous solution of the Boltzmann equation and the Poisson equation. Knowing the distribution function enables us to find the ion density profile, the average energy and energy spectrum of the

O. B. Firsov; V. V. Kuchinskii

1992-01-01

228

Analysis of thermoluminescence kinetics of CaF2(Tm) peaks with glow curve deconvolution  

Microsoft Academic Search

The purpose of this study is to achieve detailed information on kinetic parameters of the peaks of a dosimetric material. First and general order kinetic formulas are applied with a computerized deconvolution technique to CaF2(Tm) thermoluminescence glow curves. A comparison is presented between deconvolution kinetic parameters and parameters obtained applying Chen's method.

C. Bacci; P. Bernardini; A. di Domenico; C. Furetta; B. Rispoli

1990-01-01

229

Two-dimensional numerical study of atmospheric pressure glows in helium with impurities  

Microsoft Academic Search

A two-dimensional numerical model of an atmospheric pressure glow (APG) discharge was developed. The simulation of the APG in helium with some nitrogen impurities successfully reproduced the discharge evolution during the breakdown process observed in experiments. The results show that the breakdown first appears at the central region of the discharge followed by the axial and radial propagation of the

P. Zhang; U. Kortshagen

2006-01-01

230

Deposition and analysis of thin films produced in atmospheric pressure glow discharge  

Microsoft Academic Search

The atmospheric pressure glow discharge was used for the deposition of thin organosilicon polymer films. The discharge was burning in pure nitrogen used as a carrier gas with a small admixture of organosilicon compound - hexamethyldisiloxane (HMDSO) which was used as a monomer. The temperature of the substrate was elevated up to 120 °C to obtain harder thin films. The

M. Šíra; D. Franta; D. Trunec

231

Investigation of forming of electron beam in glow discharge electron guns with additional electrode  

Microsoft Academic Search

In glow discharge electron guns, for the precision control of discharge current, an additional electrode can be used. Control of the discharge current of the electron gun is provided by changing an additional electrode potential. In this work, the authors investigate the dependence of the main discharge current on the electric parameters of additional discharge and from the operation pressure

S. V. Denbnovetsky; V. I. Melnik; I. V. Melnik; K. A. Tugay

1998-01-01

232

Distribution and phylogenetic relationships of Australian glow-worms Arachnocampa (Diptera, Keroplatidae)  

Microsoft Academic Search

Glow-worms are bioluminescent fly larvae (Order Diptera, genus Arachnocampa) found only in Australia and New Zealand. Their core habitat is rainforest gullies and wet caves. Eight species are present in Australia; five of them have been recently described. The geographic distribution of species in Australia encompasses the montane regions of the eastern Australian coastline from the Wet Tropics region of

Claire H. Baker; Glenn C. Graham; Kirsten D. Scott; Stephen L. Cameron; David K. Yeates; David J. Merritt

2008-01-01

233

Atmospheric Pressure Glow Discharge Plasma and Surface Modification of PET Textile by APGDP  

Microsoft Academic Search

Comparing with traditional chemistry method, surface modification of Polyethylene terephthalate (PET) fabrics by using of Atmospheric Pressure Glow Discharge Plasma (APGDP) has many advantages, such as low cost, low pollution and low energy consumption. So it has huge application in textile industry due to no requirement for vacuum system. In this paper, the generation and the characteristics of APGDP on

Biao Gu; Ru Chen; Yin Xu; Xiang Deng; Qingjun Shi

2002-01-01

234

Comparison of ozone production in atmospheric pressure glow discharge and silent discharge  

Microsoft Academic Search

The atmospheric pressure glow discharge (APGD) was used for the ozone production. The ozone concentration was measured by\\u000a absorption spectroscopy, the consumed energy was determined from the Lissajous figures. It was demonstrated that the efficiency\\u000a of the ozone production is significantly higher in the APGD than in the silent discharge.

J. Buchta; A. Brablec; D. Trunec

2000-01-01

235

Comparison of ozone production in atmospheric pressure glow discharge and silent discharge  

NASA Astrophysics Data System (ADS)

The atmospheric pressure glow discharge (APGD) was used for the ozone production. The ozone concentration was measured by absorption spectroscopy, the consumed energy was determined from the Lissajous figures. It was demonstrated that the efficiency of the ozone production is significantly higher in the APGD than in the silent discharge.

Buchta, J.; Brablec, A.; Trunec, D.

2000-03-01

236

Glow Discharge Characteristics in Relation to Anode Size in Inertial Electrostatic Confinement Fusion  

Microsoft Academic Search

An Inertial Electrostatic Confinement Fusion device is a very simple and safe neutron source that uses a glow discharge for deuterium-deuterium fusion. The discharge characteristics of the device were studied experimentally. The relationship between gas pressure and applied voltage was examined by light changes of the device's anode size. The gas pressure ranges in which the device was able to

Hodaka Osawa; Shigehisa Yoshimura; Takehiro Tabata; Masami Ohnishi

2008-01-01

237

Glow discharge simulation of argon gas based on PIC-MCC method  

Microsoft Academic Search

Gas discharge is an important phenomenon in high voltage gas insulation. A new method PIC-MCC is used here to study the glow discharge of argon gas in low pressure. A microscopic model is established in our work and numbers of charged particles were traced by particle in cell (PIC) method. Different from other PIC methods, the collisions between electron, ion

Li Jing; Cao Yundong; Yu Longbin; Liu Xiaoming; Wu Wei

2009-01-01

238

The Blue Glow from the Back Row: Live Theater and the Wireless Teen  

ERIC Educational Resources Information Center

|Every year the author and his colleagues take their grade 12 English students to see four plays at one of Canada's major theaters. Chatting about the series on the last day of class, his students asked him if he had seen "the blue glow from the back row." Laughing at his bewilderment, they told him that during the performances so many students…

Richardson, John M.

2012-01-01

239

Physics and chemistry in a glow dielectric barrier discharge at atmospheric pressure: diagnostics and modelling  

Microsoft Academic Search

Glow dielectric barrier discharge (GDBD) appears as an attractive solution to realise an atmospheric pressure cold plasma process suitable for all the surface treatments including thin film coatings. Such a development requires a large understanding of the GDBD physics and chemistry. The objective of this work is to contribute to that understanding. From the analysis of electrical measurements, time resolved

F. Massines; P. Ségur; N. Gherardi; C. Khamphan; A. Ricard

2003-01-01

240

Plasma degradation of dyes in water with contact glow discharge electrolysis  

Microsoft Academic Search

Contact glow discharge electrolysis (CGDE) of two dyes, weak acid brilliant red B and weak acid flavine G, was investigated under different concentrations, temperature and mediums. From the variation of their concentration with the reaction time, it was demonstrated that the oxidation would be a first-order reaction. On the base line of UV spectra of solution in the degradation process,

Jinzhang Gao; Xiaoyan Wang; Zhongai Hu; Hualing Deng; Jingguo Hou; Xiaoquan Lu; Jingwan Kang

2003-01-01

241

A Study on Water Treatment Induced by Plasma with Contact Glow Discharge Electrolysis  

NASA Astrophysics Data System (ADS)

Oxidative degradation of eight kinds of dyes induced by plasma in aqueous solution was investigated with contact glow discharge electrolysis (CGDE). It has been demonstrated that these eight dyes underwent degradation in CGDE, where Fe2+ could be utilised to raise the efficiency of degradation of dyes.

Hu, Zhong-ai; Wang, Xiao-yan; Gao, Jin-zhang; Deng, Hua-ling; Hou, Jing-guo; Lu, Xiao-quan; Kang, Jing-wan

2001-10-01

242

Proton precipitation and the Hbeta emission in a postbreakup auroral glow  

Microsoft Academic Search

Measurements of the hydrogen auroral emissions have been made by rocket-borne photometers simultaneously with observations of the energy spectra and pitch angle distributions of the precipitating energetic particles. The rocket was flown through a postbreakup auroral glow known to be associated with proton precipitation on the basis of optical measurements from the ground. The observed H\\/3 profiles are compared with

F. Söraas; H. R. Lindalen; K. Mĺseide; A. Egeland; T. A. Sten; D. S. Evans

1974-01-01

243

Sacroiliac joint abnormalities in paraplegics  

Microsoft Academic Search

We studied 186 paraplegic patients to clarify the pathogenesis of the sacroiliac (SI) joint abnormalities reported in these patients. Partial or complete fusion of SI joints was noted in 47 patients (25%), and milder degrees of abnormalities of these joints were present in 27 patients (15%). The abnormalities differed from those seen in ankylosing spondylitis and were found more commonly

M A Khan; I Kushner; A A Freehafer

1979-01-01

244

Abnormal hematological indices in cirrhosis  

PubMed Central

Abnormalities in hematological indices are frequently encountered in cirrhosis. Multiple causes contribute to the occurrence of hematological abnormalities. Recent studies suggest that the presence of hematological cytopenias is associated with a poor prognosis in cirrhosis. The present article reviews the pathogenesis, incidence, prevalence, clinical significance and treatment of abnormal hematological indices in cirrhosis.

Qamar, Amir A; Grace, Norman D

2009-01-01

245

Classification of oesophageal motility abnormalities  

Microsoft Academic Search

Manometric examination of the oesophagus frequently reveals abnormalities whose cause is unknown and whose physiological importance is not clear. A large body of literature dealing with oesophageal motility abnormalities has evolved over the past few decades but comparisons among studies have been compromised by the lack of a widely accepted system for classifying the abnormal motility patterns, and by the

S J SPECHLER; D O CASTELL

2001-01-01

246

Glow in the dark cats may lead to important advances in finding a cure for HIV  

NSDL National Science Digital Library

Cats That Glow For AIDS Research Join List of Animals That Shinehttp://www.npr.org/blogs/thetwo-way/2011/09/14/140465088/cats-that-glow-for-aids-research-join-list-of-animals-that-shine'Green-Glowing' Cats May Help to Fight Against HIV/AIDShttp://www.ibtimes.com/articles/213108/20110913/glowing-cats-mayo-clinic-japan-hiv-aids.htmThe Scientist: Fluorescent Cats Aid Researchhttp://the-scientist.com/2011/09/13/fluorescent-cats-aid-research/Glowing Animals: Pictures of Beasts Shining For Sciencehttp://news.nationalgeographic.com/news/2009/05/photogalleries/glowing-animal-picturesInternational Society for Transgenic Technologieshttp://www.transtechsociety.org/The Nobel Prize in Chemistry 2008http://www.nobelprize.org/nobel_prizes/chemistry/laureates/2008/"Glow in the dark" animals have been around for a few years, but scientists at the Mayo Clinic in Minnesota and Yamaguchi University in Japan have come up with a rather curious use for such creatures. This week, researchers at these two institutions announced that they had genetically modified cats to glow in the dark. The cats were created by using a virus to carry a gene, called green fluorescent protein, into the eggs from which these animals eventually grew. It is hoped that this type of genetic modification will allow scholars to learn about vital clues for treating the AIDS virus. The idea is that scientists will now be able to monitor the activity of individual genes or cells in cats, and eventually in a number of different animals. This type of genetic modification expresses fluoresces when illuminated with UV light, which produces a green glow that scientists use to track the activity of individual genes or cells. Commenting on the work he shared with his colleagues, Eric Poeschla of the Mayo Clinic remarked, "One of the best things about this biomedical research is that it is aimed at benefiting both human and feline health." The first link will take visitors to a post from this Wednesday's NPR blog "The Two Way" about this recent discovery. The second link leads to an article from this Tuesday's International Business Times which offers some more details about the world of "green" cats. Moving along, the third link will take visitors to "The Nutshell" column from The Scientist website which also delves into fluorescence, kittens, and genetic modification. The fourth link will whisk users away to an interesting photographic feature on animals that have glowed in the name of science, courtesy of the folks at National Geographic. The fifth link leads to the homepage for the International Society for Transgenic Technologies (ISTT). Here visitors can learn about courses like "Genetics of Laboratory Rodents" and also view professional information about the ISTT and their activities. The last link will take interested parties to the official Nobel Prize page for the individuals who won the prize in 2008. They received the prize for developing the technique used by the researchers working on these cats, and the technique is now widely used throughout the world.

Grinnell, Max

2011-09-16

247

Minicolumnar abnormalities in autism.  

PubMed

Autism is characterized by qualitative abnormalities in behavior and higher order cognitive functions. Minicolumnar irregularities observed in autism provide a neurologically sound localization to observed clinical and anatomical abnormalities. This study corroborates the initial reports of a minicolumnopathy in autism within an independent sample. The patient population consisted of six age-matched pairs of patients (DSM-IV-TR and ADI-R diagnosed) and controls. Digital micrographs were taken from cortical areas S1, 4, 9, and 17. The image analysis produced estimates of minicolumnar width (CW), mean interneuronal distance, variability in CW (V (CW)), cross section of Nissl-stained somata, boundary length of stained somata per unit area, and the planar convexity. On average CW was 27.2 microm in controls and 25.7 microm in autistic patients (P = 0.0234). Mean neuron and nucleolar cross sections were found to be smaller in autistic cases compared to controls, while neuron density in autism exceeded the comparison group by 23%. Analysis of inter- and intracluster distances of a Delaunay triangulation suggests that the increased cell density is the result of a greater number of minicolumns, otherwise the number of cells per minicolumns appears normal. A reduction in both somatic and nucleolar cross sections could reflect a bias towards shorter connecting fibers, which favors local computation at the expense of inter-areal and callosal connectivity. PMID:16819561

Casanova, Manuel F; van Kooten, Imke A J; Switala, Andrew E; van Engeland, Herman; Heinsen, Helmut; Steinbusch, Harry W M; Hof, Patrick R; Trippe, Juan; Stone, Janet; Schmitz, Christoph

2006-07-04

248

Epilepsy and chromosomal abnormalities  

PubMed Central

Background Many chromosomal abnormalities are associated with Central Nervous System (CNS) malformations and other neurological alterations, among which seizures and epilepsy. Some of these show a peculiar epileptic and EEG pattern. We describe some epileptic syndromes frequently reported in chromosomal disorders. Methods Detailed clinical assessment, electrophysiological studies, survey of the literature. Results In some of these congenital syndromes the clinical presentation and EEG anomalies seems to be quite typical, in others the manifestations appear aspecific and no strictly linked with the chromosomal imbalance. The onset of seizures is often during the neonatal period of the infancy. Conclusions A better characterization of the electro clinical patterns associated with specific chromosomal aberrations could give us a valuable key in the identification of epilepsy susceptibility of some chromosomal loci, using the new advances in molecular cytogenetics techniques - such as fluorescent in situ hybridization (FISH), subtelomeric analysis and CGH (comparative genomic hybridization) microarray. However further studies are needed to understand the mechanism of epilepsy associated with chromosomal abnormalities.

2010-01-01

249

Effects of various dopants on NaCl and KCl glow curves  

NASA Astrophysics Data System (ADS)

We have measured the thermoluminescence of a number of NaCl and KCl crystals following irradiation at ambient temperature with the same dose (10 kGy) of Co-60 ? rays. We compare the TL of pure samples and of samples doped with europium and calcium ions. In the case of NaCl, additional impurities (Ni, Pb, Sr and Cr) have been investigated. The effects of irradiation are determined using optical absorption and thermoluminescence. Factors investigated include the effects of different dopants on TL glow curves and the effects of thermal annealing samples at 400 °C before the irradiation. Changes in TL glow curves relating to changes in the state of aggregation of the impurities produced by pre-irradiation annealing are reported in this paper. Perhaps the most significant effect is a temperature shift of the main glow peak in pre-annealed compared to not pre-annealed samples in the case of Eu doped NaCl. The magnitude of the shift depends on the concentration of the Eu dopant. Shifts are also observed for Ni and Sr impurities in NaCl, but not for Ca and Cr impurities in NaCl. In the case of KCl, glow peaks generally occur at similar temperatures in doped samples and do not shift when doped samples are pre-annealed. Here the main effect of different impurities is to influence the size of the emission and not the structure of the glow curve. Results are discussed in terms of current theories of thermoluminescence.

Davidson, A. T.; Kozakiewicz, A. G.; Derry, T. E.; Comins, J. D.; Suszynska, M.

2004-06-01

250

Investigation of the Dependence of Argon Metastable State Population on the Conditions of High-Frequency Glow Discharge Excitation  

NASA Astrophysics Data System (ADS)

The population of metastable states of argon atoms in high-frequency glow discharge plasma is calculated. Dependences of the population of metastable states of argon atoms in the high-frequency glow discharge plasma on the standard gas flow rate (14-30 sccm) and vibration generator power (10-50 W) in the atmospheres of pure argon and argon-silane (95% Ar + 5% SiH4) mixture are investigated together with the dependence of the population of metastable states of argon atoms in the high-frequency glow discharge plasma on the silane content (0.5-5%) in the argon-silane mixture.

Baisova, B. T.; Demin, A. S.; Pushkarev, A. A.; Strunin, V. I.; Khudaibergenov, G. Zh.

2013-06-01

251

A plasma generator based on nonself-sustained low-pressure glow discharge with a large-volume hollow cathode  

Microsoft Academic Search

The results of studying nonself-sustained glow discharges in an electrode system with a hollow cathode with a volume of 0.25\\u000a m3 are presented. A high-current (up to 35 A) nonself-sustained glow discharge at low pressures (0.3–1.0 Pa) is initiated and\\u000a sustained with the help of an auxiliary cold-hollow-cathode arc discharge. When the current of a nonself-sustained glow discharge\\u000a increases from

I. V. Lopatin; Yu. Kh. Akhmadeev; N. N. Koval’; P. M. Shchanin

2011-01-01

252

Abnormal Menstrual Cycles  

Microsoft Academic Search

After completing this chapter, you should have an understanding of the following:\\u000a \\u000a \\u000a \\u000a \\u000a – \\u000a \\u000a • The terminology of normal and abnormal menstrual function.\\u000a \\u000a \\u000a \\u000a \\u000a – \\u000a \\u000a • The causes of menstrual dysfunction.\\u000a \\u000a \\u000a \\u000a \\u000a – \\u000a \\u000a • Consequences of menstrual dysfunction in young women.\\u000a \\u000a \\u000a \\u000a \\u000a – \\u000a \\u000a • Health concerns because of menstrual dysfunction.

Reid Norman

253

Normal Modes  

NSDL National Science Digital Library

Play with a 1D or 2D system of coupled mass-spring oscillators. Vary the number of masses, set the initial conditions, and watch the system evolve. See the spectrum of normal modes for arbitrary motion. See longitudinal or transverse modes in the 1D system.

Simulations, Phet I.; Dubson, Michael; Olson, Jon; Paul, Ariel; Loeblein, Trish

2012-05-14

254

Modeling the chemical kinetics of high-pressure glow discharges in mixtures of helium with real air  

Microsoft Academic Search

Atmospheric and near-atmospheric pressure glow discharges generated in both pure helium and helium-air mixtures have been studied using a plasma chemistry code originally developed for simulations of electron-beam-produced air plasmas. Comparisons are made with experimental data obtained from high-pressure glow discharges in helium-air mixtures developed by applying sinusoidal voltage wave forms between two parallel planar metallic electrodes covered by glass

K. R. Stalder; R. J. Vidmar; G. Nersisyan; W. G. Graham

2006-01-01

255

Corrosion resistance properties of glow-discharge nitrided AISI 316L austenitic stainless steel in NaCl solutions  

Microsoft Academic Search

Glow-discharge nitriding treatments can modify the hardness and the corrosion resistance properties of austenitic stainless steels. The modified layer characteristics mainly depend on the treatment temperature. In the present paper the results relative to glow-discharge nitriding treatments carried out on AISI 316L austenitic stainless steel samples at temperatures ranging from 673 to 773K are reported. Treated and untreated samples were

A. Fossati; F. Borgioli; E. Galvanetto; T. Bacci

2006-01-01

256

Pioneer 10 ultraviolet photometer observations of the interplanetary glow at heliocentric distances from 2 to 14 AU  

Microsoft Academic Search

The interplanetary hydrogen Lyman-..cap alpha.. and He 584 A glow observations obtained by the two-channel extreme-ultraviolet photometer on Pioneer 10 at distances of 2--14 AU from the Sun are presented. The data are for the time period from 1972 to 1977. For positions near the Sun, the interplanetary glow is primarily due to single scattering of sunlight by the interstellar

F. M. Wu; K. Suzuki; R. W. Carlson; D. L. Judge

1981-01-01

257

Development of a portable greenhouse gas analyzer based on Penning ionization electron spectroscopy (PIES) in a pulsed glow discharge plasma  

Microsoft Academic Search

A greenhouse gas (GHG) analyzer currently under development at Lenterra, Inc. is described which utilizes Penning ionization electron spectroscopy (PIES) in a glow discharge plasma. A population of helium metastable atoms (2^3S, 19.8 eV) is produced in a pulsed (50 mus duration, 5 kHz rep rate) glow discharge in helium\\/analyte gas mixtures. In the afterglow electrons are produced due to

C. Mark Denning; Vadim Stepaniuk; Valery Sheverev

2009-01-01

258

Evaluation of nail abnormalities.  

PubMed

Knowledge of the anatomy and function of the nail apparatus is essential when performing the physical examination. Inspection may reveal localized nail abnormalities that should be treated, or may provide clues to an underlying systemic disease that requires further workup. Excessive keratinaceous material under the nail bed in a distal and lateral distribution should prompt an evaluation for onychomycosis. Onychomycosis may be diagnosed through potassium hydroxide examination of scrapings. If potassium hydroxide testing is negative for the condition, a nail culture or nail plate biopsy should be performed. A proliferating, erythematous, disruptive mass in the nail bed should be carefully evaluated for underlying squamous cell carcinoma. Longitudinal melanonychia (vertical nail bands) must be differentiated from subungual melanomas, which account for 50 percent of melanomas in persons with dark skin. Dystrophic longitudinal ridges and subungual hematomas are local conditions caused by trauma. Edema and erythema of the proximal and lateral nail folds are hallmark features of acute and chronic paronychia. Clubbing may suggest an underlying disease such as cirrhosis, chronic obstructive pulmonary disease, or celiac sprue. Koilonychia (spoon nail) is commonly associated with iron deficiency anemia. Splinter hemorrhages may herald endocarditis, although other causes should be considered. Beau lines can mark the onset of a severe underlying illness, whereas Muehrcke lines are associated with hypoalbuminemia. A pincer nail deformity is inherited or acquired and can be associated with beta-blocker use, psoriasis, onychomycosis, tumors of the nail apparatus, systemic lupus erythematosus, Kawasaki disease, and malignancy. PMID:22534387

Tully, Amber S; Trayes, Kathryn P; Studdiford, James S

2012-04-15

259

Microdischarge-assisted ignition of dielectric-barrier high-pressure glow discharges  

NASA Astrophysics Data System (ADS)

The ignition characteristics of dielectric-barrier high-pressure glow (DB-HPG) discharges in the presence of dc microdischarges are studied for pure helium and pure nitrogen working gases. In the presence of an array of microdischarges integrated with one of the DB-HPG electrodes, a substantial reduction of DB-HPG ignition voltage is observed for both working gases. The discharge structure within the DB-HPG volume gap is localized near the microdischarge holes when the DB-HPG first turns on in the presence of microdischarges, but subsequently expands to cover the entire volume at higher voltages for the pressures studied. The helium discharge is generally more uniform than the nitrogen gas. Our studies indicate that the localized discharge has a glow-like character rather than a Townsend- or streamer-like one.

Shin, Jichul; Raja, Laxminarayan L.

2006-01-01

260

Estimation of electron temperature in transient glow discharge using ionization wave  

SciTech Connect

Through ionization waves (striation), the transition of glow discharge to arc discharge was observed and relevant electron temperatures were determined experimentally. The velocity of ionization waves in a cathode flare increased from twofold to threefold that in an anode flare. It was assumed that the electron temperature of an anode flare was 4.0-fold to 8.4-fold higher than that in a dark space, and the typical electron temperatures in a dark space and an anode flare were 1.8x10{sup 3} and 1.0x10{sup 4} K, respectively. The electron temperature of the anode flare agreed well with the theoretical value of a positive column in steady glow discharge.0.

Hoshi, Y.; Yokota, A.; Yoshida, H.; Akedo, J. [National Institute of Advanced Industrial Science and Technology, AIST Tsukuba East, Tsukuba, Ibaraki 305-8564 (Japan)

2006-07-01

261

Glow corona generation and streamer inception at the tip of grounded objects during thunderstorms: revisited  

NASA Astrophysics Data System (ADS)

The initiation of streamers prior to a lightning strike can be reportedly inhibited by glow corona discharges generated from tall objects. In contrast to previous studies based on a simplified one-dimensional model of glow corona, a two-dimensional evaluation of the corona ion drift from tall objects is used here to analyse this effect quantitatively. Proper estimates for the corona space charge distribution generated during both the charging process of a thundercloud and the descent of the downward stepped leader are thus calculated. It is found that the shielding effect of the corona space charge on the streamer inception is not as severe as previously reported. Estimations of the effective height of the downward leader tip at which streamer inception takes place are presented and discussed for lightning rods and dissipation array systems.

Becerra, Marley

2013-04-01

262

Inner Surface Modification of a Tube by Magnetic Glow-Arc Plasma Source Ion Implantation  

NASA Astrophysics Data System (ADS)

A new method named the magnetic glow-arc plasma source ion implantation (MGA-PSII) is proposed for inner surface modification of tubes. In MGA-PSII, under the control of an axial magnetic field, which is generated by an electric coil around the tube sample, glow arc plasma moves spirally into the tube from its two ends. A negative voltage applied on the tube realized its inner surface implantation. Titanium nitride (TiN) films are prepared on the inner surface of a stainless steel tube in diameter 90 mm and length 600 mm. Hardness tests show that the hardness at the tube centre is up to 20 GPa. XRD, XPS and AES analyses demonstrate that good quality of TiN films can be achieved.

Zhang, Gu-Ling; Wang, Jiu-Li; Wu, Xing-Fang; Feng, Wen-Ran; Chen, Guang-Liang; Gu, Wei-Chao; Niu, Er-Wu; Fan, Song-Hua; Liu, Chi-Zi; Yang, Si-Ze

2006-05-01

263

Determination of potassium and sodium ions with diaphragm glow discharge plasma in aqueous solution  

NASA Astrophysics Data System (ADS)

In the present work, a new apparatus of diaphragm glow discharge emission spectroscopy was described for the determination of potassium and sodium ions in aqueous solution. The discharge was formed in a pin hole on a dielectric diaphragm interposed between two submerged graphite electrodes. Effects of pH and applied voltage on the determination have been examined. It was found that decreasing the solution pH and increasing the applied voltage were favorable for the determination performance. Limits of detection for Na and K were 0.002 and 0.05 mg L-1 under the optimum conditions, respectively. It demonstrates that the diaphragm glow discharge emission spectroscopy is a promising technique in measurements of metal ions in aqueous solution, because no optical interferences from the electrodes were found.

Liu, Yongjun; Sun, Bing; Wang, Lei

2013-03-01

264

COATING AND MANDREL EFFECTS ON FABRICATION OF GLOW DISCHARGE POLYMER NIF SCALE INDIRECT DRIVE CAPSULES  

SciTech Connect

OAK A271 COATING AND MANDREL EFFECTS ON FABRICATION OF GLOW DISCHARGE POLYMER NIF SCALE INDIRECT DRIVE CAPSULES. Targets for the National Ignition Facility (NIF) need to be about 200 {micro}m thick and 2 mm in diameter. These dimensions are well beyond those currently fabricated on a routine basis. They have investigated fabrication of near NIF scale targets using the depolymerizable mandrel technique. Poly-alpha-methylstyrene (PAMS) mandrels, about 2 mm in diameter, of varying qualities were coated with as much as 125 {micro}m of glow discharge polymer (GDP). The surface finish of the final shells was examined using a variety of techniques. A clear dependence of the modal spectrum of final GDP shell on the quality of the initial PAMS mandrels was observed. isolated features were found to be the greatest cause for a shell not meeting the NIF standard.

NIKROO,A; PONTELANDOLFO,JM; CASTILLO,ER

2002-04-01

265

Attenuation of single-tone ultrasound by an atmospheric glow discharge plasma barrier  

SciTech Connect

Propagation of 143 kHz ultrasound through an atmospheric pressure glow discharge in air was studied experimentally. The plasma was a continuous dc discharge formed by a multipin electrode system. Distributions of the gas temperature were also obtained in and around the plasma using laser-induced Rayleigh scattering technique. Results show significant attenuation of the ultrasound by the glow discharge plasma barrier (up to -24 dB). The results indicate that sound attenuation does not depend on the thickness of the plasma and attenuation is caused primarily by reflection of the sound waves from the plasma due to the sharp gas temperatures gradients that form at the plasma boundary. These gradients can be as high as 80 K/mm.

Stepaniuk, Vadim P. [Lenterra Inc., 7 Tenney Road, West Orange, New Jersey 07052 (United States); Ioppolo, Tindaro; Oetuegen, M. Volkan [Southern Methodist University, 3101 Dyer Street, Dallas, Texas 75205 (United States); Sheverev, Valery A. [Lenterra Inc., 7 Tenney Road, West Orange, New Jersey 07052 (United States); Polytechnic Institute of NYU, 6 Metrotech Center, Brooklyn, New York 11201 (United States)

2010-09-15

266

Microdischarge-assisted ignition of dielectric-barrier high-pressure glow discharges  

SciTech Connect

The ignition characteristics of dielectric-barrier high-pressure glow (DB-HPG) discharges in the presence of dc microdischarges are studied for pure helium and pure nitrogen working gases. In the presence of an array of microdischarges integrated with one of the DB-HPG electrodes, a substantial reduction of DB-HPG ignition voltage is observed for both working gases. The discharge structure within the DB-HPG volume gap is localized near the microdischarge holes when the DB-HPG first turns on in the presence of microdischarges, but subsequently expands to cover the entire volume at higher voltages for the pressures studied. The helium discharge is generally more uniform than the nitrogen gas. Our studies indicate that the localized discharge has a glow-like character rather than a Townsend- or streamer-like one.

Shin Jichul; Raja, Laxminarayan L. [Department of Aerospace Engineering and Engineering Mechanics, University of Texas at Austin, Austin, Texas 78712 (United States)

2006-01-09

267

Time series analysis of ionization waves in dc neon glow discharge  

NASA Astrophysics Data System (ADS)

The dynamics of dc neon glow discharge is examined by calculating a Lyapunov exponent spectrum (LES) and correlation dimension (Dcorr) from experimental time series. The embedding theory is used to reconstruct an attractor with the delay coordinate method. The analysis refers to periodic, chaotic, and quasi-periodic attractors. The results obtained are confirmed by a comparison with other methods of time series analysis such as the Fourier power spectrum and autocorrelation function. The main object of the present work is the positive column of a dc neon glow discharge. The positive column is an excellent model for the study of a non-linearity plasma system because it is nonisothermal plasma far from equilibrium.

Hassouba, M. A.; Al-Naggar, H. I.; Al-Naggar, N. M.; Wilke, C.

2006-07-01

268

Estimation of electron temperature in transient glow discharge using ionization wave  

NASA Astrophysics Data System (ADS)

Through ionization waves (striation), the transition of glow discharge to arc discharge was observed and relevant electron temperatures were determined experimentally. The velocity of ionization waves in a cathode flare increased from twofold to threefold that in an anode flare. It was assumed that the electron temperature of an anode flare was 4.0-fold to 8.4-fold higher than that in a dark space, and the typical electron temperatures in a dark space and an anode flare were 1.8×103 and 1.0×104 K, respectively. The electron temperature of the anode flare agreed well with the theoretical value of a positive column in steady glow discharge.

Hoshi, Y.; Yokota, A.; Yoshida, H.; Akedo, J.

2006-07-01

269

Radiative lifetime and collisional quenching of carbon monochloride (A 2?) in an alternating current glow discharge  

Microsoft Academic Search

Glow discharges are widely employed in semiconductor processing but are relatively poorly understood owing to, in part, a lack of reliable, quantitative diagnostics. Laser-induced fluorescence promises to be a useful in situ, nonintrusive probe for species concentrations and gas-phase temperatures, but requires the determination of fluoresence yields (i.e., radiative vs nonradiative decay rates) as a function of the plasma state

Richard A. Gottscho; Randolph H. Burton; Glenn P. Davis

1982-01-01

270

Frequency and voltage dependence of glow and pseudoglow discharges in helium under atmospheric pressure  

Microsoft Academic Search

The pseudoglow and glow discharge behavior of a 0.5-mm metallic-dielectric electrode gap in helium under atmospheric pressure was examined as a function of ac voltage between 0.3 and 32 kHz. The number of discharge current pulses per half-cycle within the pseudoglow was found to diminish with rising frequency, as opposed to the increase observed with rising voltage. The reduction in

Ion Radu; Ray Bartnikas; Michael R. Wertheimer

2003-01-01

271

A Study on Helium Glow Discharge Cleaning in the HL1M Tokamak  

Microsoft Academic Search

Based on the principle of ion-bombarded reemission and sputtering desorption, the Glow Discharge Cleaning with helium (GDC(He)) is an effective method for controlling the recycle of H on the chamber wall, Carbon (C), Oxygen (O) impurity and improving the wall conditioning in HL-1M tokamak. It is characterized by simplicity without magnet and safety, compared with Taylor Discharge Cleaning (TDC), Alternating

Zhi-wen Wang; Dong-hai Yan; En-yao Wang

2002-01-01

272

Dielectric Electrode Surface Effects on Atmospheric Pressure Glow Discharges in Helium  

Microsoft Academic Search

Comparative experimental and theoretical studies are carried with 0.5-mm gaps using metallic and dielectric electrodes to examine the influence of dielectric surfaces upon the behavior of atmospheric pressure glow discharges in helium at frequencies of up to 22 kHz. The charge transfers associated with the discrete discharge current pulses exhibit a direct proportionality to the difference between the breakdown Vb

R. Bartnikas; I. Radu; M. R. Wertheimer

2007-01-01

273

Plasma nitriding of aluminium in a pulsed dc glow discharge of nitrogen  

Microsoft Academic Search

Plasma nitriding of aluminium in a 50 Hz pulsed-dc glow discharge is studied for different ion-current densities (2.0-5.0 mA cm-2) by keeping the corresponding discharge parameters such as treatment time, chamber pressure, substrate temperature and gas composition same. The treated samples are analysed for changes induced in surface properties using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray

S. Naseer; F. U. Khan; N. U. Rehman; A. Qayyum; F. Rahman; M. Zakaullah

2010-01-01

274

Computational study of capacitively coupled high-pressure glow discharges in helium  

Microsoft Academic Search

The structure of a capacitively coupled high-pressure glow (HPG) discharge in high-purity helium is investigated using a detailed one-dimensional modeling approach. Impurity effects are modeled using trace amounts of nitrogen gas in helium. Average electron temperatures and densities for the HPG discharge are similar to their low-pressure counterpart. Helium-dimer ions dominate the discharge structure for sufficiently high-current densities, but model

Xiaohui Yuan; Laxminarayan L. Raja

2003-01-01

275

Surface cleaning of metals in air with a one atmosphere uniform glow discharge plasma  

Microsoft Academic Search

Summary form only given, as follows. We report the use of active species generated in a one atmosphere uniform glow discharge plasma reactor with a parallel-plate configuration to clean the surface of as-received metal samples from the machine shop floor. The unmagnetized air plasma in this reactor had the following characteristic operating and plasma parameters: RF frequency, 1-4 kHz; RMS

J. Reece Roth; Yongmin Ku

1995-01-01

276

Infrared emission spectroscopy of glow discharge formed in low pressure atmospheric gases  

NASA Astrophysics Data System (ADS)

Laboratory study was conducted on the molecular and atomic emissions which are considered detectable in the IR radiative background of the upper atmosphere. The IR spectra of glow discharge emission formed in air and other atmospheric constituent gases of 0.1-Torr pressure and a 30-m long column were surveyed using the technique of Fourier spectroscopy. Several features hitherto unobserved were detected in our survey study.

Sakai, H.; Hansen, P.; Esplin, M.; Johansson, R.; Peltola, M.; Strong, J.

1982-01-01

277

Femtosecond Laser Ablation Particle Introduction to a Liquid Sampling-Atmospheric Pressure Glow Discharge Ionization Source  

Microsoft Academic Search

This work describes the use of a compact, liquid sampling atmospheric pressure glow discharge (LS-APGD) ionization source to ionize metal particles within a laser ablation aerosol. Mass analysis was performed with a Thermo Scientific Exactive Mass Spectrometer which utilizes an orbitrap mass analyzer capable of producing mass resolution exceeding M\\/M > 160,000. The LS-APGD source generates a low-power plasma between

Anthony J. Carado; C. Derrick Quarles; Andrew M. Duffin; Charles J. Barinaga; Richard Russo; R. Kenneth Marcus; Gregory C. Eiden; David W. Koppenaal

2012-01-01

278

Decoloration of alizarin red S in aqueous solution by glow discharge electrolysis  

Microsoft Academic Search

The oxidation of alizarin red S by hydroxyl radicals, which were generated from glow discharge electrolysis, was investigated. Various influencing factors such as the applied voltage, the initial pH, the catalytic action of Fe2+ ion and the distance between cathode and anode were examined. Chemical oxygen demand (COD), ultraviolet (UV) absorption spectra, atomic force microscopy (AFM) and gas chromatogram–mass spectrum

Jinzhang Gao; Jie Yu; Quanfang Lu; Xiaoyan He; Wu Yang; Yan Li; Lumei Pu; Zhiming Yang

2008-01-01

279

Evidence for graphitic-type bonding in glow discharge hydrogenated amorphous silicon carbon alloys  

Microsoft Academic Search

Amorphous silicon carbon (a-SiC:H) films have been deposited by the glow discharge technique using SiH4 and CH4 gas mixtures. At high discharge powers and low deposition chamber pressures, evidence for graphitic-type bonding in C-deficient a-SiC:H is found and correlations are made between the appearance of this bonding with significant changes in the electronic and structural properties. This graphitic-type bonding can

A. H. Mahan; B. von Roedern; D. L. Williamson; A. Madan

1985-01-01

280

Spatially Resolved Temperature Measurements of Atmospheric-Pressure Normal Glow Microplasmas in Air  

Microsoft Academic Search

The rotational and vibrational temperatures of DC normal glow air discharges were measured by comparing modeled optical emission spectra of the N2 second positive system with spectroscopic measurements from the discharges. By using an imaging spectrometer and optical assembly, the temperature measurements were spatially resolved to about 6 mum. Results are presented for a 3.8-mA discharge at an electrode spacing

David Staack; Bakhtier Farouk; Alexander F. Gutsol; Alexander Fridman

2007-01-01

281

Characteristics of a LaB6 hollow cathode in the glow-arc transition  

Microsoft Academic Search

A new type of a simple LaB6 hollow cathode tube allows us to have very stable discharge even in the regime of the glow-arc transition, which is commonly unstable for widely used cathode materials (Ta,W). Because of the relatively large size of our device (25 mm diameter) and the low-temperature operation (~1400 K), we were able to investigate various plasma

Akira Tonegawa; Kazuo Takayama

1990-01-01

282

Drag force reduction on an airfoil via glow discharge plasma-based control  

Microsoft Academic Search

Glow discharge plasma on a solid surface will result in a body force which modifies the pressure distribution along the flow\\u000a boundary layer, and consequently re-attaches the separated flows for reduction of a hydrodynamic drag force. In this paper,\\u000a we investigate the discharge performance of various plasma-actuated electrodes in terms of their arrangements and structures.\\u000a The resulting optimal configuration for

X. Fu; Y. Li; B. Li; D. Y. Kwok

2009-01-01

283

Characterization of W Coating on Cu Substrate Prepared by Double-Glow Discharge  

Microsoft Academic Search

In this study, tungsten (W) was coated on a copper (Cu) substrate by using double-glow discharge technique using a pure W panel as the target and argon (Ar) as the discharge and sputtering gas. The crystal structure of the W coating was examined by X-ray diffraction (XRD). Scanning electron microscopy (SEM) was performed with cross-section images to investigate the penetration

Zhang Fubin; Wang Zhengduo; Chen Qiang; Cai Huiping

2012-01-01

284

Surface Modification of Commercial Low-Carbon Steel using Glow Discharge Nitrogen Plasma and its Characterization  

NASA Astrophysics Data System (ADS)

Plasma nitriding under glow discharge nitrogen plasma has been undertaken on laboratory scale for surface engineering of commercial low carbon steels. The treatment has been shown to confer exceptional improvement in surface properties, viz., hardness and corrosion resistance. The results have been discussed in light of microstructural changes occurring on steel surface and its interior as a result of Fickian nitrogen diffusion and correlated with influences of nitriding-temperature and alloying elements (Mn, Nb, and Si) in steel.

Srikanth, S.; Saravanan, P.; Joseph, Alphonsa; Ravi, K.

2013-09-01

285

Emission characteristics of mixed gas plasmas in low-pressure glow discharges  

Microsoft Academic Search

Glow discharge optical emission spectrometry (GD-OES) with mixed plasma gases is reviewed. The major topic is the effect of type and content of gases added to an argon plasma on the emission characteristics as well as the excitation processes. Emphasis is placed on argon–helium, argon–oxygen, and argon–nitrogen mixed gas plasmas. Results for non-argon-matrix plasmas, such as neon–helium and nitrogen–helium mixtures,

Kazuaki Wagatsuma

2001-01-01

286

Altruism, Warm Glow and the Willingness-to-Donate for Green Electricity: An Artefactual Field Experiment  

Microsoft Academic Search

The ongoing liberalization of electricity markets in most western countries forms the background of our artefactual field experiment. Using a Cheap talk design [R.G. Cummings and L.O. Taylor. American Economic Review89 (1999) 649–665] with supplementary monetary incentives, we test for presence of “warm glow” motivations [J. Andreoni. Journal of Political Economy97 (1989) 1447–1458; Economic Journal100 (1990) 464–477] in the willingness-to-donate

Roland Menges; Carsten Schroeder; Stefan Traub

2005-01-01

287

Study of a DC Glow Discharge Supplied by a Flyback Converter  

SciTech Connect

An experimental method aimed to study the characteristics of the equivalent electrical circuit for the dc glow discharges is described. The high voltage necessary to initiate and sustain the discharge is provided by a self-oscillating flyback converter. The flyback converter is also used to detect the discharge changes. The detection principle is based on the variation of the flyback converter electrical parameters (supply current, duty cycle and operating frequency) as a function of the load characteristics.

Stoican, O. S. [INFLPR, Bucharest-Magurele, 077125 (Romania)

2007-04-23

288

Submicronic etching of borophosphosilicate glass using NF 3 and NF 3\\/He radio frequency glow discharge  

Microsoft Academic Search

The etching of borophosphosilicate glass (BPSG) in NF3 and NF3\\/He radio frequency (RF) glow discharge has been characterized. The etch rates, BPSG\\/resist selectivity and etch profile have been investigated along with the reactor geometry, namely the inter electrode distance, by which the process can be optimized. The results shows that the etch rates of BPSG are 650 nm\\/min at RF

N. Mekkakia Maaza; A. Boudghene Stambouli

2004-01-01

289

Microcrystalline silicon thin films using dc saddle-field glow discharge  

Microsoft Academic Search

Microcrystalline silicon (\\/spl mu\\/c-Si:H) thin films offer the potential of increased stability against photo-induced degradation, improved spectral utilization in all silicon multi-junction amorphous-microcrystalline solar cells, and efficient doping. Recently we have prepared \\/spl mu\\/c-Si:H films, consisting of crystalline grains embedded in an amorphous network, using the dc saddle-field glow discharge deposition method. Increasing presence of microcrystallinity with decreasing silane concentration

N. P. Kherani; T. Allen; F. Gaspari; T. Kosteski; K. Leong; I. Milostnaya; D. Yeghikyan; S. Zukotynski

2003-01-01

290

Aqueous p-nitrotoluene oxidation induced with direct glow discharge plasma  

Microsoft Academic Search

A plasma induced degradation process has been studied to treat 4-nitrotoluene (4-NT) present as an aqueous pollutant. The\\u000a plasma was locally generated from a glow discharge around a tip of a platinum anode in an electrolytic solution. The influence\\u000a of initial pH and Fe2+ on the degradation was examined. Major intermediates resulting from the degradation process were identified. Amongst the

Jinzhang Gao; Yongjun Liu; Wu Yang; Lumei Pu; Jie Yu; Quanfang Lu

2005-01-01

291

Abnormal phenomena in a one-dimensional periodic structure containing left-handed materials  

Microsoft Academic Search

The explicit dispersion equation for a one-dimensional periodic structure\\u000awith alternative layers of left-handed material (LHM) and right-handed material\\u000a(RHM) is given and analyzed. Some abnormal phenomena such as spurious modes\\u000awith complex frequencies, discrete modes and photon tunnelling modes are\\u000aobserved in the band structure. The existence of spurious modes with complex\\u000afrequencies is a common problem in the

Liang Wu; Sailing He; Linfang Shen

2002-01-01

292

Hypergeometric modes.  

PubMed

A new family of paraxial laser beams that form an orthogonal basis is discussed. When propagated in uniform space, these beams preserve their structure to scale. The intensity distribution profile for such beams is similar to that for the Bessel modes, representing a set of alternating bright and dark concentric rings. The complex amplitude of these beams is proportional to the degenerate (confluent) hypergeometric function, and therefore we term such beams hypergeometric (HyG) modes. The HyG modes are generated with a liquid-crystal microdisplay. PMID:17339921

Kotlyar, V V; Skidanov, R V; Khonina, S N; Soifer, V A

2007-04-01

293

Hypergeometric modes  

NASA Astrophysics Data System (ADS)

A new family of paraxial laser beams that form an orthogonal basis is discussed. When propagated in uniform space, these beams preserve their structure to scale. The intensity distribution profile for such beams is similar to that for the Bessel modes, representing a set of alternating bright and dark concentric rings. The complex amplitude of these beams is proportional to the degenerate (confluent) hypergeometric function, and therefore we term such beams hypergeometric (HyG) modes. The HyG modes are generated with a liquid-crystal microdisplay.

Kotlyar, V. V.; Skidanov, R. V.; Khonina, S. N.; Soifer, V. A.

2007-04-01

294

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

SciTech Connect

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

Safaai, S. S.; Yap, S. L.; Wong, C. S.; Muniandy, S. V. [Plasma Research Laboratory, Physics Department, Faculty of Science, University of Malaya, 50603 KualaLumpur (Malaysia); Smith, P. W. [University of Oxford (United Kingdom)

2010-07-07

295

Electrode Polarity Effects in Direct Current Glow Discharges for Supersonic Flow Control  

NASA Astrophysics Data System (ADS)

Computational simulations of air glow discharge plasma in the presence of supersonic flow are presented. The glow discharge model is based on a self-consistent, multi-species, continuum description of the plasma. A finite-rate air chemistry model with 11 species is validated against experiments from the literature at p=600 mTorr. The validated air plasma model is then used to study the effect of the surface plasma on M=3 supersonic flow at freestream pressure 18 Torr and the corresponding effects of the flow on the discharge structure. The Navier-Stokes equations are solved on the entire computational domain, and the plasma equations are solved on a smaller subdomain consistent with the typical length-scale of the glow discharge. Results indicate that O^- can have comparable concentrations to electrons in the pressure range 1-20 Torr. The peak gas temperature from the computations is found to be 1420 K with the surface plasma alone, and 1180 K in the presence of supersonic flow with the cathode located upstream with respect to the flow direction. The effect of placing the cathode downstream with respect to the flow direction is investigated. For the case studied in this work the primary effect of the plasma on the supersonic flow is volumetric heating.

Mahadevan, Shankar; Raja, Laxminarayan

2009-10-01

296

Mechanism behind self-sustained oscillations in direct current glow discharges and dusty plasmas  

NASA Astrophysics Data System (ADS)

An alternative explanation to the mechanism behind self-sustained oscillations of ions in direct current (DC) glow discharges is provided. Such description is distinguished from the one provided by the fluid models, where oscillations are attributed to the positive feedback mechanism associated with photoionization of particles and photoemission of electrons from the cathode. Here, oscillations arise as consequence of interaction between an ion and the surface charges induced by it at the bounding electrodes. Such mechanism provides an elegant explanation to why self-sustained oscillations occur only in the negative resistance region of the voltage-current characteristic curve in the DC glow discharges. Furthermore, this alternative description provides an elegant explanation to the formation of plasma fireballs in the laboratory plasma. It has been found that oscillation frequencies increase with ion's surface charge density, but at the rate which is significantly slower than it does with the electric field. The presented mechanism also describes self-sustained oscillations of ions in dusty plasmas, which demonstrates that self-sustained oscillations in dusty plasmas and DC glow discharges involve common physical processes.

Nae Cho, Sung

2013-04-01

297

Mixed- and general-order kinetics applied to selected thermoluminescence glow curves.  

PubMed

Mixed-order (MO) and general-order (GO) kinetics expressions are applied to experimental glow curves of CaSO4:Ce, LiNaSO4:Eu, BaF2:Ce and SrF2:Er. The purpose is to compare the activation energies derived from the two models to investigate the correlation between the order of kinetics, b, and the parameter alpha of the MO model for real systems and to explore the validity of the correlation between b and alpha derived from the analysis of synthetic glow peaks or experimentally isolated single peak for complex glow curves. The two alternative routes resulted in clean fits with very close values of the sum of squared residuals. The general conclusions are: (1) the activation energies derived from the MO model are slightly higher than the ones derived from the GO model, but the difference appears to be insignificant, (2) the correlation between b and alpha is not smooth and the scatter in the b values for a given alpha is within the theoretically expected spread in the b value and (3) the MO expression is capable of evaluating the shape parameters as accurately as the GO expression with the advantage that it has a physical basis contrary to the purely empirical GO model. PMID:18337288

Maghrabi, M; Al-Jundi, J; Arafah, D-E

2008-03-12

298

Plasma Cathodes as Electron Sources for Large Volume, High-Pressure Glow Discharges  

NASA Astrophysics Data System (ADS)

A method to suppress the glow-to-arc transition in high pressure glow discharges is the use of a plasma cathode consisting of microhollow cathode discharges (MHCD) [1]. In our experiment a microhollow cathode discharge with a 100 micrometer diameter cathode hole and identical anode hole was used to provide electrons for a large volume main discharge, sustained between the hollow anode of the MHCD and a third electrode. Current and voltage characteristics, and the visual appearance of the main discharge and MHCD were studied in argon and air by using the micro plasma cathode as electron source. We are able to get stable dc operation in argon up to 1 atm and in air up to 600 torr. The main discharge is ignited when the current in the plasma cathode (MHCD), which is on the order of mA, reaches a threshold value. This threshold current increases with reduced applied voltage across the main gap. Above this transition the current in the main discharge is on the same order as the MHCD current and can be controlled by the MHCD current. Experiments with two MHCDs in parallel have indicated that large area high pressure stable glow discharges can be generated by using arrays of MHCDs as electron sources. [1] K. H. Schoenbach et al, Plasma Sources Sci. Techn. 6, 468 (1997). This work was solely funded by the Air Force Office of Scientific Research (AFOSR) in cooperation with the DDR&E Air Plasma Ramparts MURI program.

Stark, Robert H.; Schoenbach, Karl H.

1998-10-01

299

Distribution and phylogenetic relationships of Australian glow-worms Arachnocampa (Diptera, Keroplatidae).  

PubMed

Glow-worms are bioluminescent fly larvae (Order Diptera, genus Arachnocampa) found only in Australia and New Zealand. Their core habitat is rainforest gullies and wet caves. Eight species are present in Australia; five of them have been recently described. The geographic distribution of species in Australia encompasses the montane regions of the eastern Australian coastline from the Wet Tropics region of northern Queensland to the cool temperate and montane rainforests of southern Australia and Tasmania. Phylogenetic trees based upon partial sequences of the mitochondrial genes cytochrome oxidase II and 16S mtDNA show that populations tend to be clustered into allopatric geographic groups showing overall concordance with the known species distributions. The deepest division is between the cool-adapted southern subgenus, Lucifera, and the more widespread subgenus, Campara. Lucifera comprises the sister groups, A. tasmaniensis, from Tasmania and the newly described species, A. buffaloensis, found in a high-altitude cave at Mt Buffalo in the Australian Alps in Victoria. The remaining Australian glow-worms in subgenus Campara are distributed in a swathe of geographic clusters that extend from the Wet Tropics in northern Queensland to the temperate forests of southern Victoria. Samples from caves and rainforests within any one geographic location tended to cluster together within a clade. We suggest that the morphological differences between hypogean (cave) and epigean (surface) glow-worm larvae are facultative adaptations to local microclimatic conditions rather than due to the presence of cryptic species in caves. PMID:18583158

Baker, Claire H; Graham, Glenn C; Scott, Kirsten D; Cameron, Stephen L; Yeates, David K; Merritt, David J

2008-05-03

300

Acoustic Shock Wave Propagation in a Glow Discharge(Supported by Accurate Automation Corporation.)  

NASA Astrophysics Data System (ADS)

Experiments with weak acoustic shock waves propagating through glow discharges(A. I. Klimov et al., Sov. Tech Phys. Lett. 8), 192 (1982).^,(B. N. Ganguly et al., Phys. Lett. A 230), 218 (1997). have shown unexpected damping, dispersion, and propagation effects that still remain to be understood. Similar effects were observed for both monoatomic and molecular gas discharges. Increase of shock velocity propagation is more pronounced in the cathode region of a d.c. glow discharge then in the positive column.(S. Popovi?) and L. Vu\\vskovi?, Physics of Plasmas 6, 1448 (1999). This and other observations suggested that pure thermal effects only could not explain the observed shock modification. In the present analysis of the observed phenomena, we started from the hypothesis that electronic excitation is the controlling process in the energy storage and transfer along the shock structure. Further, we explored the shock structure similarity of weak shock waves in glow discharges and strong shock waves in monoatomic neutral gases, where the accumulated excited state population was observed in leader and precursor regions. A detailed time-dependent approach for describing the ionization-recombination process was used to demonstrate the possibility of sufficient energy storage to account for the observed shock modification.

Popovi?, S.; Vuškovi?, L.

1999-10-01

301

Atmospheric sampling glow discharge ionizataion and triple quadrupole tandem mass spectrometry for explosives vapor detection  

SciTech Connect

The detection and identification of trace vapors of hidden high explosives is an excellent example of a targeted analysis problem. It is desirable to push to ever lower levels the quantity or concentration of explosives material that provides an analytical signal, while at the same time discriminating against all other uninteresting material. The detection system must therefore combine high sensitivity with high specificity. This report describes the philosophy behind the use of atmospheric sampling glow discharge ionization, which is a sensitive, rugged, and convenient means for forming anions from explosives molecules, with tandem mass spectrometry, which provides unparalleled specificity in the identification of explosives-related ions. Forms of tandem mass spectrometry are compared and contrasted to provide a summary of the characteristics to be expected from an explosives detector employing mass spectrometry/mass spectrometry. The instrument developed for the FAA, an atmospheric sampling glow discharge/triple quadrupole mass spectrometer, is described in detail with particular emphasis on the ion source/spectrometer interface and on the capabilities of the spectrometer. Performance characteristics of the system are also described as they pertain to explosives of interest including a description of an automated procedure for the detection and identification of specific explosives. A comparison of various tandem mass spectrometers mated with atmospheric sampling glow discharge is then described and preliminary studies with a vapor preconcentration system provided by the FAA will be described.

McLuckey, S.A.; Goeringer, D.E.; Asano, K.G.; Hart, K.J.; Glish, G.L.; Grant, B.C.; Chambers, D.M.

1993-08-01

302

Glow discharge cleaning and vacuum deposition of copper on 6061-T6 aluminum  

SciTech Connect

Prior to plating electroless nickel onto a part made of 6061-T6 aluminum, several aqueous pretreatment steps are required which end with the deposition of a thin copper layer covering the part. In an effort to minimize the quantity and type of wastes generated during this pretreatment process, vacuum deposition methods are under evaluation as an alternative. Six vacuum cleaning/copper deposition experiments have been conducted on 6061-T6 aluminum coupons. The coupons were glow discharge cleaned at 1500, 2000 and 2500 volts and a copper coating was either sputtered deposited or ion plated onto the aluminum substrate. The results showed that the adhesive strength of the copper coating was greatest for those coupons cleaned at 2500 volts and ion plated. Glow discharge cleaning was greatest for those coupons cleaned at 2500 volts and ion plated. Glow discharge cleaning at 1500 and 2000 volts resulted in copper films that were porous while those cleaned at 2500 volts were not. The results further showed that ion plated copper films of appropriate thickness can be produced while the aluminum alloy is precipitation hardened. 3 refs., 9 figs., 3 tabs.

Vasofsky, R.W.; Corbett, W.D. Jr.

1991-02-25

303

Chromosomal abnormalities and mental illness  

Microsoft Academic Search

Linkage studies of mental illness have provided suggestive evidence of susceptibility loci over many broad chromosomal regions. Pinpointing causative gene mutations by conventional linkage strategies alone is problematic. The breakpoints of chromosomal abnormalities occurring in patients with mental illness may be more direct pointers to the relevant gene locus. Publications that describe patients where chromosomal abnormalities co-exist with mental illness

D J MacIntyre; D H R Blackwood; D J Porteous; B S Pickard; W J Muir

2003-01-01

304

Systemic abnormalities in liver disease  

PubMed Central

Systemic abnormalities often occur in patients with liver disease. In particular, cardiopulmonary or renal diseases accompanied by advanced liver disease can be serious and may determine the quality of life and prognosis of patients. Therefore, both hepatologists and non-hepatologists should pay attention to such abnormalities in the management of patients with liver diseases.

Minemura, Masami; Tajiri, Kazuto; Shimizu, Yukihiro

2009-01-01

305

Electrocardiograph abnormalities revealed during laparoscopy  

PubMed Central

This brief case presents a well patient in whom an electrocardiograph abnormality consistent with an accessory pathway was found during a routine procedure. We present the electrocardiographs, explain the underlying condition, and consider why the abnormality was revealed in this manner.

Nijjer, Sukhjinder; Dubrey, Simon William

2010-01-01

306

Radiographic abnormalities in Laron dwarfism  

Microsoft Academic Search

Radiographic abnormalities in two children with Laron dwarfism are described. In addition to a characteristic bone age, which was retarded for the chronological age but advanced for the height of the patients, there were marked skull changes and minor skeletal abnormalities in the long bones and vertebrae. Such findings on a skeletal survey should lead the radiologist to suspect the

M. Vasil; A. Baxova; K. Kozlowski

1994-01-01

307

Potential Industrial Applications of the One Atmosphere Uniform Glow Discharge Plasma (OAUGDP) Operating in Ambient Air  

NASA Astrophysics Data System (ADS)

The majority of industrial plasma processing with glow discharges has been conducted at pressures below 10 torr. This tends to limit applications to high value workpieces as a result of the high capital cost of vacuum systems and the production constraints of batch processing. It has long been recognized that glow discharge plasmas would play a much larger industrial role if they could be generated at one atmosphere. The One Atmosphere Uniform Glow Discharge Plasma (OAUGDP), developed at the University of Tennessee's Plasma Sciences Laboratory, is a non-thermal RF plasma operating on displacement currents with the time-resolved characteristics of a classical low pressure DC normal glow discharge. As a glow discharge, the OAUGDP operates with maximum electrical efficiency at the Stoletow point, where the energy input per ion-electron pair is a minimum [1, 2]. Several interdisciplinary teams have investigated potential applications of the OAUGDP. These teams included collaborators from the UTK Textiles and Nonwovens Development Center (TANDEC), and the Departments of Electrical and Computer Engineering, Microbiology, and Food Science and Technology, as well as the NASA Langley Research Center. The potential applications of the OAUGDP have all been at one atmosphere and room temperature, using air as the working gas. These applications include sterilizing medical and dental equipment; sterilizable air filters to deal with the "sick building syndrome"; removal of soot from Diesel engine exhaust; subsonic plasma aerodynamic effects, including flow re-attachment to airfoils and boundary layer modification; electrohydrodynamic (EDH) flow control of working gases; increasing the surface energy of materials; improving the adhesion of paints and electroplated layers: improving the wettability and wickability of fabrics; stripping of photoresist; and plasma deposition and directional etching of potential microelectronic relevance. [1] J. R. Roth, Industrial Plasma Engineering: Volume I, Principles. Institute of Physics Publishing, Bristol and Philadelphia 1995, ISBN 0-7503-0318-2. [2] Roth, J. R. Industrial Plasma Engineering: Volume II Applications to Nonthermal Plasma Processing Institute of Physics Publishing, Bristol and Philadelphia. 2001, ISBN 0-7503-0545-2.

Reece Roth, J.

2004-11-01

308

Detection of Abnormalities in MANETs.  

National Technical Information Service (NTIS)

Abnormalities in MANETs can be malicious attacks or selfish nodes which can affect network architecture and network operation significantly. Clearly, there are two distinct objectives: 1) To design/examine attacks and develop countermeasures and 2) design...

W. Wang

2007-01-01

309

Abnormal States of Nuclear Matter.  

National Technical Information Service (NTIS)

Results for abnormal states in nuclear matter are reviewed and compared with pi exp - condensates in the context of chiral invariance and the sigma model. The relative importance of symmetry breaking and conserving interactions is assessed for the two pro...

L. Castillejo

1975-01-01

310

Peri-implant hard tissue response to glow-discharged abutments: prospective study. Preliminary radiological results.  

PubMed

In the literature has been demonstrated that when an implant is placed in the oral environment, changes in peri-implant hard tissue level may occur. Several clinical procedures have been advocated to clinically minimize this bone resorption. However, minimal attention was paid to the soft- and hard-tissue abutment interaction. The present clinical preliminary study is intended to radiologically analyze the effect of glow-discharged abutments on hard tissue level changes after 18 months of prosthetic loading. Five patients needing an implant supported restoration in the anterior maxillary area with thin gingival tissue biotype and healed bone were recruited. An implant was inserted and a titanium abutment was glow-discharged with an Argon plasma treatment in a plasma reactor and, immediately after, definitively screwed at 30N. Provisional restoration was therefore positioned. Three months later, definitive restoration was performed. Digital periapical standardized radiographs were taken at the time of surgery, 6 and 18 months thereafter. Radiographic analysis was carried out using image analysis software. At baseline, interproximal radiographs revealed no bone defect around implants in both groups. After 6 months from baseline, the postoperative interproximal radiographs revealed an average bone loss of 0.09mm (range 0.0-0.3mm, SD=0.144mm). After 18 months from baseline, the periapical X-ray showed a stable condition of bone remodeling (mean value: 0.09, range 0.0-0.5mm, SD=0.08mm). Within the limit of this study, glow-discharged abutments have been demonstrated to positively affect hard tissue reaction to implant restoration. PMID:22564880

Canullo, Luigi; Götz, Werner

2012-04-18

311

Investigation of plasma distribution in electron-focused electric field enhanced glow discharge plasma immersion ion implantation  

SciTech Connect

In enhanced glow discharge plasma immersion ion implantation (EGDPIII) that involves a small pointed anode and large area tabular cathode, the high negative substrate bias not only acts as the plasma producer but also supplies the implantation voltage. Consequently, an electric field is created to focus the electrons and the electron-focusing field enhances the glow discharge process. In this work, the plasma distribution is measured using a Langmuir probe to obtain the plasma density. Numerical interpolation is performed to obtain the plasma density distribution throughout the entire discharge region. The effects of different distances between the anode and cathode on the glow discharge characteristics and the influence of the plasma electron density are also evaluated. Our results experimentally verify the electron-focusing phenomenon and suggest optimal processing windows for enhanced ionization rates and efficiency in EGDPIII.

Lu Qiuyuan; Li Liuhe [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong); Department 702, School of Mechanical and Automation Engineering, Beijing University of Aeronautics and Astronautics, Beijing (China); Fu, Ricky K. Y.; Chu, Paul K. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong)

2008-08-15

312

First principle based calculation of emission properties of positive column of Ar-SnI2 glow discharge  

NASA Astrophysics Data System (ADS)

Possibility of replacement of mercury, an environmental hazard, by non-toxic elements in gas discharge lamps is intensively investigated now. Gases of metal halides are regarded as candidates of non-equilibrium source of emitters (metals) in glow discharge plasma. The model of glowing discharge in Ar/SnI2 plasma is built using multilevel approach [1] for calculation of the cross sections and rate constant of electron collision with the metal halides. Sensitivity analysis shows, that dissociative attachment is one of the most important processes in that elecronegative medium and directly influences on steady state parameters of glow discharge plasma. Optimization of the discharge parameters and conclusion about maximal light emission efficiency is performed. [4pt] [1] Adamson S. et al. J. Phys. D: Appl. Phys. 2007. V.40. P.3857

Deminsky, Maxim; Tudorovskaia, Maria; Chernysheva, Irina; Potapkin, Boris; Michael, Darryl; Smith, David; Sommerer, Timothy

2009-10-01

313

Investigation of the characteristics of thermoluminescence glow curves of natural hydrothermal quartz from Hakkari area in Turkey  

NASA Astrophysics Data System (ADS)

In this study the dosimetric characteristics of some natural hydrothermal quartz (NHQ) samples collected from Hakkari were investigated by using the thermoluminescence (TL) technique for the purpose of determining whether they are suitable as dosimetric materials or not and calculating the kinetic parameters. The experiments carried out can be outlined as: analyzing TL glow curves of NHQ; determining the annealing conditions; the effects of pre-irradiation annealing procedures on TL sensitivity; the investigation of the characteristics of TL glow curves obtained after annealing the samples; determination of the trap parameters with the computerized glow curve deconvolution (CGCD) method and the peak shape (PS) method. The obtained results showed that the trap depths and the frequency factor values are consistent with the literature. The studied samples have linear dose responses for the absorbed doses ranging between ~6.689 Gy and ~301 Gy. In conclusion, the examined quartz samples can be used as dosimetric materials in high dose applications.

Topaksu, M.; Yüksel, M.; Dogan, T.; Nur, N.; Akkaya, R.; Yegingil, Z.; Topak, Y.

2013-09-01

314

Ion focusing in enhanced glow discharge plasma immersion ion implantation of hydrogen and nitrogen into silicon  

SciTech Connect

Ion focusing in enhanced glow discharge plasma immersion ion implantation (EGD-PIII) of hydrogen into silicon affects the lateral ion fluence uniformity. The phenomenon and its effects are investigated experimentally and theoretically under different conditions and compared to those in nitrogen EGD-PIII. Consistent results are obtained from experiments and numerical simulation disclosing that the lower the plasma density, the more severe is the ion focusing effect. The influence of the negative high voltage on the ion focusing effect is small compared to that of the plasma density.

Lu Qiuyuan; Fu, Ricky K. Y.; Chu, Paul K. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong); Wang Zhuo; Li Liuhe [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong); Department 702, School of Mechanical and Automation Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China)

2010-08-15

315

Influence of annular magnet on discharge characteristics in enhanced glow discharge plasma immersion ion implantation  

SciTech Connect

A permanent annular magnet positioned at the grounded anode alters the discharge characteristics in enhanced glow discharge plasma immersion ion implantation (EGD-PIII). The nonuniform magnetic field increases the electron path length and confines electron motion due to the magnetic mirror effect and electron-neutral collisions thus occur more frequently. The plasma potential and ion density measured by a Langmuir probe corroborate that ionization is improved near the grounded anode. This hybrid magnetic field EGD-PIII method is suitable for implantation of gases with low ionization rates.

Li Liuhe; Wang Zhuo [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong); Department 702, School of Mechanical and Automation Engineering, Beijing University of Aeronautics and Astronautics, Beijing (China); Lu Qiuyuan; Fu, Ricky K. Y.; Chu, Paul K. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong); Pang Enjing; Dun Dandan; He Fushun; Li Fen [Department 702, School of Mechanical and Automation Engineering, Beijing University of Aeronautics and Astronautics, Beijing (China)

2011-01-10

316

Heat transfer between tungsten surface and glow discharge plasmas in argon and CO2  

NASA Astrophysics Data System (ADS)

A hot-filament method is used to study the heat transfer between tungsten surface and hollow-cathode glow discharge plasmas in argon and CO2. The dependence of the electric power supplied to a tungsten wire on the discharge current is determined for argon and carbon dioxide in the temperature range between 1000 and 1700 K. A difference in heat transfer at the tungsten wire surface is found between experiments on argon and carbon dioxide. The difference is attributed to heterogeneous recombination in CO2 plasma.

Polikarpov, F. D.; Polikarpov, A. F.; Borisov, S. F.; Nikulin, S. P.; Tretnikov, P. V.

2009-10-01

317

Atomic recombination into excited molecular - A possible mechanism for Shuttle glow  

NASA Astrophysics Data System (ADS)

The present class of energetic collision mechanisms may be responsible for the glow observed above Space Shuttle surfaces exposed to energetic collisions with ambient atmospheric constituents in orbit, since the collisional energies involved are sufficient for the dissociation of atmospheric N2 on impact with Shuttle surfaces. At Space Shuttle altitudes, collisional quenching is negligible; the metastable N2 A molecules slowly decay radiatively to form N2 B molecules on a millisecond time scale, and then rapidly radiate to the A state to produce the red N2 'First Positive Bands'.

Green, B. D.

1984-06-01

318

Microparticle transport in an argon dc glow discharge dusty plasma due to an applied temperature gradient  

NASA Astrophysics Data System (ADS)

In recent years, increasing interest has focused on dust transport under microgravity plasma conditions. Earlier work studied dusty plasmas under reduced gravity conditions during sounding rocket flights [Morfill et al, Phys Rev Letters, 83, 1598 (1999)]. Ground-based experiments used temperature gradients in rf-generated complex plasmas to simulate reduced gravity conditions [Rothermel et al, Phys Rev Letters, 89, 175001 (2002)]. This presentation will discuss dust particle transport due to a thermophoretic force in an argon dc glow discharge plasma. Laser illumination and particle image velocimetry (PIV) are used to determine dust particle transport. Results of transport measurements are compared to a time dependant model for dust motion.

Engel, Patricia; Silver, Jennifer; Thomas, Edward

2004-11-01

319

Oxidative Degradation of o-Chlorophenol with Contact Glow Discharges in Aqueous Solution  

NASA Astrophysics Data System (ADS)

Contact glow discharge electrolysis (CGDE) of o-chlorophenol (2-CP) was investigated under different pH, voltages and initial concentrations. And the mechanism of the oxidation was explored. The results suggested that the degradation followed the first order kinetic law; Fe2+ had a remarkable catalytic effect on the removal rate of o-chloropenol. In the presence of Fe2+, 2-CP underwent an exhaustive degradation, from which the major intermediates included o-dihydroxybenze, p-hydroxybenze, p-benzoquione and carboxlic acids.

Gao, Jin-zhang; Yang, Wu; Liu, Yong-jun; Chen, Ping; Na, Peng-jun; Lu, Quan-fang

2003-02-01

320

Degradation of Chloroanilines in Aqueous Solution by Contact Glow Discharge Electrolysis  

NASA Astrophysics Data System (ADS)

Contact glow discharge electrolysis of some chloroanilines in sodium sulfate was investigated in different initial concentrations. Each of them underwent the dechlorination, deamination through oxidative degradation, and were eventually decomposed into hydrogen carbonate and carbon dioxide. It was testified that the chlorine atom and amidogen could be transformed into chloride ion and nitrite ion, respectively. Fe2+ has a remarkable catalytic effect on the degradation of them. On the basis of the detailed analysis of the intermediate products and kinetic behaviors, the reaction pathway was proposed, in which the attack of hydroxyl radical on the benzene ring of starting material might be a key step.

Gao, Jin-zhang; Hu, Zhong-ai; Lu, Quan-fang; Na, Peng-jun; Chen, Ping; Liu, Yong-jun; Yu, Jie

2003-04-01

321

Genetic effects of radio-frequency, atmospheric-pressure glow discharges with helium  

SciTech Connect

Due to low gas temperatures and high densities of active species, atmospheric-pressure glow discharges (APGDs) would have potential applications in the fields of plasma-based sterilization, gene mutation, etc. In this letter, the genetic effects of helium radio-frequency APGD plasmas with the plasmid DNA and oligonucleotide as the treated biomaterials are presented. The experimental results show that it is the chemically active species, instead of heat, ultraviolet radiation, intense electric field, and/or charged particles, that break the double chains of the plasmid DNA. The genetic effects depend on the plasma operating parameters, e.g., power input, helium flow rate, processing distance, time, etc.

Li Guo; Li Heping; Wang Sen; Sun Wenting; Bao Chengyu [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Wang Liyan; Zhao Hongxin; Xing Xinhui [Department of Chemical Engineering, Tsinghua University, Beijing 100084 (China)

2008-06-02

322

The nature of anomalous sky glow connected with the Tungusk phenomenon  

NASA Astrophysics Data System (ADS)

A quantitative interpretation of the anomalous sky glow observed on the night of June 30-July 1, 1908 (and on subsequent nights) over a vast area from western Siberia to the British Isles is presented. The mechanism of the secondary scattering of sunlight by the dust that was contained in the coma of the Tungusk comet and entered the earth atmosphere simultaneously with the Tungusk object is considered. The volume density and optical properties of the dust particles were found to be the same as those in the coma of Comet Halley.

Bronshten, V. A.

1991-08-01

323

Efficient methane conversion to hydrogen and hydrocarbons by combination of corona and glow discharge  

NASA Astrophysics Data System (ADS)

In this study we offer a new type of plasma which consists of double, corona and glow, discharge to convert natural gas, the main part of which is methane. The most important future of this type of plasma is the steady increase of overall chemical energy efficiency by enhancement of repetition rate. At repetition rate of R=80 Hz, the energy efficiency of 5.5% was increased to 10% at R=330 Hz and more improvement was yet expected at higher repetition rates. Easy control of selectivity of products that were hydrogen, acetylene, ethylene, ethane and hydrocarbons with up to 5 carbons, was also possible by repetition rate.

Ghorbanzadeh, A. M.; Matin, N. S.

2004-03-01

324

Ciliary abnormalities in respiratory disease.  

PubMed

One hundred and sixty seven children, ranging in age from 5 weeks to 16 years, with chronic upper or lower respiratory tract problems, or both, were investigated for ciliary dyskinesia. Abnormal ciliary function was found in 18 cases all of whom had chronic lower respiratory disease and most of whom also had upper respiratory problems. Fifteen of the 18 cases had reduced ciliary beat frequencies (less than 10 Hz) associated with dyskinesia and the other three showed apparent absence of ciliated cells. Of the 15 cases with reduced ciliary beat frequencies, ciliary ultrastructure was normal in seven cases but abnormal with missing dynein arms and occasional abnormalities of microtubular arrangement in eight. Respiratory symptoms in the perinatal period were more common in children with abnormal ciliary function and present in all those with ultrastructural abnormalities or absence of ciliated cells compared with 34 (26%) of 132 children, in whom symptoms were recorded, with normal ciliary function. This study would suggest that all children with unexplained chronic respiratory disease, in particular those with symptoms starting in the perinatal period, should be investigated for ciliary dyskinesia. PMID:3355203

Buchdahl, R M; Reiser, J; Ingram, D; Rutman, A; Cole, P J; Warner, J O

1988-03-01

325

Aerodynamic flow acceleration using paraelectric and peristaltic electrohydrodynamic effects of a One Atmosphere Uniform Glow Discharge Plasma  

NASA Astrophysics Data System (ADS)

The development of the One Atmosphere Uniform Glow Discharge Plasma has made it possible to cover the wings and fuselage of aircraft with a thin layer of glow discharge plasma at low energy cost. This plasma layer provides, through Lorentzian collisions, a purely electrohydrodynamic coupling between an electric field and the neutral gas in the boundary layer. This coupling is strong enough to cause aerodynamically significant acceleration and manipulation of the boundary layer and free stream flow, including re-attachment of flow to an airfoil at high angles of attack, and the peristaltic induction of neutral gas flow by a traveling electrostatic wave on the surface of a flat plate.

Roth, J. Reece

2003-05-01

326

Theoretical investigation of sheath expansion and implant fluence uniformity in enhanced glow discharge plasma immersion ion implantation  

SciTech Connect

In enhanced glow discharge plasma immersion ion implantation that involves a small-pointed anode and large area tabular cathode, the high negative substrate bias acts as the plasma producer and supplies the implantation voltage. An electric field is created to focus the electrons and the electron-focusing field in turn enhances the glow discharge process. The sheath physics is theoretically investigated using numerical simulation based on the multiple-grid particle-in-cell code. Electron focusing is corroborated and the plasma sheath has enough expansion when t=40 {mu}s so that a uniform distribution of the incident ion fluence is attained.

Kwok, Dixon T. K.; Fu, Ricky K. Y.; Chu, Paul K. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong); Lu Qiuyuan; Li Liuhe [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong); Department 702, School of Mechanical and Automation Engineering, Beijing University of Aeronautics and Astronautics, Beijing (China)

2008-09-01

327

Lymphocyte abnormalities in Behçet's syndrome.  

PubMed

In order to test indirectly the hypothesis that Behçet's syndrome is caused by a virus, lymphocytes from eighty-six patients were evaluated for two parameters consistent with persistent virus infection: chromosomal abnormalities and decreased ability to herpes simplex virus type I (HSV) to grow in lymphocyte cultures stimulated by PHA. Whereas HSV grew in lymphocytes cultured from all normal donors, replication was impaired in lymphocytes from 37% of the patients with Behçet's syndrome. This figure is increased to 57% if patients receiving steroids or cytotoxic drugs were excluded. Lymphocytes were scored as chromosomally abnormal from sixteen of the thirty-eight patients examined, compared with only one of seventeen normal controls. There was damage to specific chromosomes in four patients. The frequency with which chromosomal abnormalities were detected was significantly related to failure to replicate HSV and inversely related to concomitant steroid treatment. The findings are consistent with a viral aetiology for Behçet's syndrome but other explanations are not excluded. PMID:6161726

Denman, A M; Fialkow, P J; Pelton, B K; Salo, A C; Appleford, D J; Gilchrist, C

1980-10-01

328

Effect of surface modification of high-density polyethylene by direct current and radio frequency glow discharge on wetting and adhesion characteristics  

NASA Astrophysics Data System (ADS)

The present investigation aims to optimize the process parameters of Direct Current (DC) and Radio Frequency (RF) glow discharge treatment through air in terms of discharge power and time of exposure for the surface modification of high-density polyethylene (HDPE) sheet, for attaining best adhesive joint of the polymer to mild steel. In order to estimate the extent of surface modification, the surface energies of the polymer surfaces exposed to glow discharge have been determined by measuring contact angles using two standard test liquids of known surface energies. It is observed that at a given power level of DC glow discharge, surface energy and its polar component increase with increasing exposure time, attaining a maximum and then decreasing. In the case of RF glow discharge, surface energy and its polar component increase with increasing exposure time and then saturate. Surface modification by DC glow discharge increases the surface energy of HDPE relatively more at a lower power compared to that observed for RF glow discharge. The dispersion component of surface energy remains almost unaffected. The surfaces have also been studied by electron spectroscopy for chemical analysis (ESCA) and energy-dispersive spectra (EDS). A significant oxygen peak is observed for surface-modified polymer as detected by ESCA and EDS. Lap shear tensile test of an adhesive (Araldite AY 105) joint of HDPE with mild steel has been carried out in optimizing the parameters of DC and RF glow discharge for maximum joint strength. When HDPE is exposed to DC glow discharge, improvement of adhesive joint strength of HDPE to mild steel is found to be by a factor more than 7. On the other hand, when HDPE is exposed to RF glow discharge, results in improvement of adhesive joint strength of HDPE to mild steel by a factor nearer to 7 are found. Thus, DC glow discharge is more capable for increasing wetting and adhesion characteristics of the polymer.

Bhowmik, S.; Chaki, T. K.; Ray, S.; Hoffman, F.; Dorn, L.

2004-03-01

329

Liquid Sampling-Atmospheric Pressure Glow Discharge Ionization Source for Elemental Mass Spectrometry  

SciTech Connect

A new, low power ionization source for elemental MS analysis of aqueous solutions is described. The liquid sampling-atmospheric pressure glow discharge (LSAPGD) operates by a process wherein the surface of the liquid emanating from a 75 ?m i.d. glass capillary acts as the cathode of the direct current glow discharge. Analytecontaining solutions at a flow rate of 100 ?L min-1 are vaporized by the passage of current, yielding gas phase solutes that are subsequently ionized in the < 5 W (maximum of 60 mA and 500 V), ~1 mm3 volume, plasma. The LS-APGD is mounted in place of the normal electrospray ionization source of a Thermo Scientific Exactive orbitrap mass spectrometer system. Basic operating characteristics are described, including the role of discharge power on mass spectral composition, the ability to obtain ultra-high resolution elemental isotopic patterns, and preliminary limits of detection attainable based on the injection of aliquots of multielement standards. While much optimization remains, it is believed that the LS-APGD may present a practical alternative to high-powered (>1 kW) plasma sources typically employed in elemental mass spectrometry, particularly for those cases where costs, operational overhead, and simplicity considerations are important.

Marcus, R. Kenneth; Quarles, C. Derrick; Barinaga, Charles J.; Carado, Anthony J.; Koppenaal, David W.

2011-04-01

330

Charging of dust grains in a nonequilibrium plasma of a stratified glow discharge  

SciTech Connect

A theoretical model is presented that describes the charging of dust grains in the positive plasma column of a stratified glow dc discharge in argon. A one-dimensional self-consistent model is used to obtain axial profiles of the electric field, as well as the electron energy distribution function along the axis of the discharge tube. Radial profiles of the electric field are determined in the ambipolar diffusion approximation. It is assumed that, in the radial direction, the electron distribution function depends only on the total electron energy. Two-dimensional distributions of the discharge plasma parameters are calculated and used to determine the potential and charge of a test dust grain at a certain point within the discharge and the electrostatic forces acting on it. It is shown that the grain charge distribution depends strongly on the nonequilibrium electron distribution function and on the nonuniform distribution of the electric field in a stratified glow discharge. A discussion is presented on the suspension of dust grains, the separation of grains by size in the discharge striations, and a possible mechanism for the onset of vortex dust motion at the edge of a dust cloud.

Sukhinin, G. I.; Fedoseev, A. V. [Russian Academy of Sciences, Kutateladze Institute of Thermophysics, Siberian Branch (Russian Federation)

2007-12-15

331

Influence of the transverse dimension on the structure and properties of dc glow discharges  

SciTech Connect

Two-dimensional (2D) simulations of a dc glow discharge with a cold cathode in argon have been performed for various radii of the discharge tube. It is shown that the loss of the charged particles to the walls can significantly affect plasma parameters as well as properties of the cathode sheath. The longitude dimensions of the negative glow and Faraday dark space depend on the transverse loss of the charge particles and are not consistently predicted with a 1D model. The common assumption that the cathode sheath can be analyzed independently of the plasma also may not be valid. The transverse inhomogeneity of the plasma leads to a change in the current density distribution over the cathode surface. The thickness of the cathode sheath can vary with radial distance from the discharge axis, even for the case of negligible radial loss of the charge particles. The 2D model results provide an analysis of the conditions of applicability of the 1D model.

Bogdanov, E. A. [St. Petersburg State University, St. Petersburg 198904 (Russian Federation); Adams, S. F. [Air Force Research Laboratory, Wright-Patterson AFB, Ohio 45433 (United States); Demidov, V. I. [Department of Physics, West Virginia University, Morgantown, West Virginia 26506 (United States); Kudryavtsev, A. A. [Department of Optics, St. Petersburg State University, St. Petersburg 198904 (Russian Federation); Williamson, J. M. [UES, Inc., 4401 Dayton-Xenia Rd., Beavercreek, Ohio 45432 (United States)

2010-10-15

332

Charge mitigation techniques using glow and corona discharges for advanced gravitational wave detectors  

NASA Astrophysics Data System (ADS)

Charging of silica test masses in gravitational wave detectors could potentially become a significant low-frequency noise source for advanced detectors. Charging noise has already been observed and confirmed in the GEO600 detector and is thought to have been observed in one of the LIGO detectors. In this paper, two charge mitigation techniques using glow and corona discharges were investigated to create repeatable and robust procedures. The glow discharge procedure was used to mitigate charge under vacuum and would be intended to be used in the instance where an optic has become charged while the detector is in operation. The corona discharge procedure was used to discharge samples at atmospheric pressure and would be intended to be used to discharge the detector optics during the cleaning of the optics. Both techniques were shown to reduce both polarities of surface charge on fused silica to a level that would not limit advanced LIGO. Measurements of the transmission of samples that had undergone the charge mitigation procedures showed no significant variation in transmission, at a sensitivity of ~ 200 ppm, in TiO2-doped Ta2O5/SiO2 multi-layer coated fused silica.

Campsie, P.; Cunningham, L.; Hendry, M.; Hough, J.; Reid, S.; Rowan, S.; Hammond, G. D.

2011-11-01

333

Radio-frequency powered glow discharge device and method with high voltage interface  

SciTech Connect

A high voltage accelerating potential, which is supplied by a high voltage direct current power supply, is applied to the electrically conducting interior wall of an RF powered glow discharge cell. The RF power supply desirably is electrically grounded, and the conductor carrying the RF power to the sample held by the probe is desirably shielded completely excepting only the conductor's terminal point of contact with the sample. The high voltage DC accelerating potential is not supplied to the sample. A high voltage capacitance is electrically connected in series between the sample on the one hand and the RF power supply and an impedance matching network on the other hand. The high voltage capacitance isolates the high DC voltage from the RF electronics, while the RF potential is passed across the high voltage capacitance to the plasma. An inductor protects at least the RF power supply, and desirably the impedance matching network as well, from a short that might occur across the high voltage capacitance. The discharge cell and the probe which holds the sample are configured and disposed to prevent the probe's components, which are maintained at ground potential, from bridging between the relatively low vacuum region in communication with the glow discharge maintained within the cell on the one hand, and the relatively high vacuum region surrounding the probe and cell on the other hand. The probe and cell also are configured and disposed to prevent the probe's components from electrically shorting the cell's components.

Duckworth, Douglas C. (Knoxville, TN); Marcus, R. Kenneth (Clemson, SC); Donohue, David L. (Vienna, AT); Lewis, Trousdale A. (Oak Ridge, TN)

1994-01-01

334

PRODUCTION OF HIGHER STRENGTH THIN WALLED GLOW DISCHARGE POLYMER SHELLS FOR CRYOGENIC EXPERIMENTS AT OMEGA  

SciTech Connect

OAK A271 PRODUCTION OF HIGHER STRENGTH THIN WALLED GLOW DISCHARGE POLYMER SHELLS FOR CRYOGENIC EXPERIMENTS AT OMEGA. Thin walled polymer shells are needed for OMEGA cryogenic laser experiments. These capsules need to be about 900 {micro}m in diameter and as thin as possible (approx 1-2 {micro}m), while having enough strength to be filled with DT as fast as possible to about 1000 atm. The authors have found that by optimizing the coating parameters in the glow discharge polymer (GDP) deposition system, traditionally used for making ICF targets, they can routinely make robust, {approx} 1.5 {micro}m thick, 900 {micro}m diameter GDP shells with buckle strengths of over 0.3 atm. This is twice the strength of shells made prior to the optimization and is comparable to values quoted for polyimide shells. In addition, these shells were found to be approximately three times more permeable and over 20% denser than previously made GDP shells. The combination of higher strength and permeability is ideal for direct drive cryogenic targets at OMEGA. Shells as thin as 0.5 {micro}m have been made. In this paper, the authors discuss the shell fabrication process, effects of modifying various GDP deposition parameters on shell properties and chemical composition.

NIKROO,A; CZECHOWICZ,DG; CASTILLO,ER; PONTELANDOLFO,JM

2002-04-01

335

Thermoluminescence in pure LiF crystals: Glow peaks and their connection with color centers  

SciTech Connect

Nominally pure LiF crystals were irradiated with the same dose (0.85 10{sup 6} R) of gamma rays at ambient and low temperatures (-60 deg. C) and the resulting thermoluminescence (TL) is reported. Various optical and thermal treatments were applied in order to change the concentration of color centers (CCs). The effect of such treatments on the glow curves is observed. Knowing the coloration from optical transmission and photoluminescence measurements made on the same samples, we attribute many of the glow peaks (GPs) to the annealing of F center aggregates. For the present conditions of irradiation and dose, TL processes begin with decay of F{sub 3}{sup +} centers that display a GP at 164 deg. C. F{sub 3}(R) centers follow and are responsible for GPs at 193 and 228 deg. C. A GP at 263 deg. C is ascribed to F{sub 2} centers. Several peaks at temperatures in the range of 280-380 deg. C are associated with impurity perturbed F centers. A GP at 410 deg. C is associated with a complex of aggregated F and H centers. These attributions are accomplished by means of TL spectra, optical transmission spectra, and annealing procedures, and are critically discussed. The experimental data confirm the general trend of thermal stability of CCs, which decreases by moving from simple F centers to more complex ones, and the existence of exchange dynamics among CCs.

Baldacchini, G.; Montereali, R. M. [Department of Physical Technologies and New Materials-Frascati Research Center, ENEA, Via E. Fermi 45, Frascati, Roma 00044 (Italy); Nichelatti, E. [Department of Physical Technologies and New Materials-Casaccia Research Center, ENEA, S. Maria di Galeria, Roma 00123 (Italy); Kalinov, V. S.; Voitovich, A. P. [Institute of Physics, Academy of Sciences of Belarus, 70 Nezavisimosti Ave., 220067 Minsk (Belarus); Davidson, A. T.; Kozakiewicz, A. G. [Department of Chemistry, University of Zululand, Kwadlangezwa 3886 (South Africa)

2008-09-15

336

Atmospheric Pressure Glow Discharge Plasma and Surface Modification of PET Textile by APGDP  

NASA Astrophysics Data System (ADS)

Comparing with traditional chemistry method, surface modification of Polyethylene terephthalate (PET) fabrics by using of Atmospheric Pressure Glow Discharge Plasma (APGDP) has many advantages, such as low cost, low pollution and low energy consumption. So it has huge application in textile industry due to no requirement for vacuum system. In this paper, the generation and the characteristics of APGDP on a homemade device were investigated experimentally. The volt-ampere characteristic and the Lissajous figure demonstrated that, different from dielectric barrier discharge (DBD), there is no filaments appeared between electrodes. It is a glow discharge in one atmospheric pressure. Furthermore we investigated the surface modification of PET by APGDP. The relationship between PET characteristics (wettability, critical surface tension, timing-effect, dyeablity etc.) and various discharge parameters are discussed. At last, the measurements of ATR-FTIR (Attenuated Total Refraction-Fourier Transform Infarared Spectroscopy) and dyeing properties are demonstrated, and the mechanism of modification is analyzed basically. Key words: APGDPŁ¬Surface modification , PET

Gu, Biao; Chen, Ru; Xu, Yin; Deng, Xiang; Shi, Qingjun

2002-11-01

337

LET and dose dependence of TLD-100 glow curve after exposure to intermediate-energy ions.  

PubMed

We present results from measurements performed with low fluences (10(5)-10(6) cm(-2)) of 15, 25 and 40 MeV u(-1) carbon, 25 MeV u(-1) oxygen and 40 MeV u(-1) neon ions incident on TLD-100 chips. Dosemeters were arranged individually or in stacks in front of the beam, allowing the study of various linear energy transfer (LET) values simultaneously. The thermoluminescence (TL) total signal is observed to be a linear function of deposited energy. To assess the contribution to the glow curve from the high-temperature peaks, two methods were studied: ratios of peak heights (peak 7 with respect to peak 5), and ratios of areas of the deconvoluted high-temperature peaks with respect to peak 5. The ratios were evaluated as a function of dose, showing in both methods a dependence on LET and ion identity. Some of the studied ions show these ratios to be independent of dose, up to 500 mGy, while for other ions, departures from linearity up to 4.5% +/- 2.5% per 100 mGy are observed at 500 mGy. These results show that, in general, the incident radiation LET is not a parameter that can be deduced from the glow curve. PMID:16565204

Massillon-Jl, G; Gamboa-deBuen, I; Brandan, M E

2006-03-24

338

Modified Waste Emplacement Mode Design Alternative Report  

Microsoft Academic Search

The alternative emplacement modes presented in this report provide potential conceptual design options to the VA design that enhance human access to the emplacement drift area during abnormal events. The alternative conceptual designs emplace waste packages in configurations that reduce the level of radiation exposure utilizing shield doors, shield plugs, and concrete slabs to allow for human access during off-normal

Rick Wilson

1999-01-01

339

Extracellular Matrix Abnormalities in Schizophrenia  

PubMed Central

Emerging evidence points to the involvement of the brain extracellular matrix (ECM) in the pathophysiology of schizophrenia (SZ). Abnormalities affecting several ECM components, including Reelin and chondroitin sulfate proteoglycans (CSPGs), have been described in subjects with this disease. Solid evidence supports the involvement of Reelin, an ECM glycoprotein involved in corticogenesis, synaptic functions and glutamate NMDA receptor regulation, expressed prevalently in distinct populations of GABAergic neurons, which secrete it into the ECM. Marked changes of Reelin expression in SZ have typically been reported in association with GABA-related abnormalities in subjects with SZ and bipolar disorder. Recent findings from our group point to substantial abnormalities affecting CSPGs, a main ECM component, in the amygdala and entorhinal cortex of subjects with schizophrenia, but not bipolar disorder. Striking increases of glial cells expressing CSPGs were accompanied by reductions of perineuronal nets, CSPG- and Reelin-enriched ECM aggregates enveloping distinct neuronal populations. CSPGs developmental and adult functions, including neuronal migration, axon guidance, synaptic and neurotransmission regulation are highly relevant to the pathophysiology of SZ. Together with reports of anomalies affecting several other ECM components, these findings point to the ECM as a key component of the pathology of SZ. We propose that ECM abnormalities may contribute to several aspects of the pathophysiology of this disease, including disrupted connectivity and neuronal migration, synaptic anomalies and altered GABAergic, glutamatergic and dopaminergic neurotransmission.

Berretta, Sabina

2011-01-01

340

Transcriptional abnormalities in Huntington disease  

Microsoft Academic Search

Huntington disease (HD) is caused by a CAG repeat expansion that is translated into an abnormally long polyglutamine (polyQ) tract in the huntingtin protein. The precise mechanisms leading to neurodegeneration in HD have not been fully elucidated, but alterations in gene transcription could well be involved because the activities of several nuclear proteins are compromised by the polyQ mutation. Recent

Katharine L. Sugars; David C. Rubinsztein

2003-01-01

341

Abnormal waves during Hurricane Camille  

Microsoft Academic Search

A reanalysis is reported of the wave time series recorded during Hurricane Camille having as objective the identification of individual waves that satisfy current criteria defining abnormal or freak waves. It is shown that during the hurricane development, a very nonstationary situation has occurred during which the second-order sea state parameters changed significantly with time. The parameters of the largest

C. Guedes Soares; Z. Cherneva; E. M. Antăo

2004-01-01

342

Journal of Abnormal Psychology: Editorial  

Microsoft Academic Search

In keeping with tradition, the editor of the current issue of the Journal of Abnormal Psychology (1980, Vol. 89, No. 4) presents an account of his policies and goals for the benefit of readers and potential authors. The author discusses the Journal's coverage, criteria for acceptance, types of articles, evaluation procedures, and the blind review process.

Alexander M. Buchwald

1980-01-01

343

Anxiety, pregnancy, and childbirth abnormalities  

Microsoft Academic Search

Women who later experienced complications or had abnormal children show higher manifest anxiety scores in the 7th month of pregnancy. For those retested, differences were not significant 6 weeks later. From Psyc Abstracts 36:01:3HK74D.

Anthony Davids; Spencer Devault; Max Talmadge

1961-01-01

344

Account of nonlocal ionization by fast electrons in the fluid models of a direct current glow discharge  

SciTech Connect

We developed and tested a simple hybrid model for a glow discharge, which incorporates nonlocal ionization by fast electrons into the 'simple' and 'extended' fluid frameworks. Calculations have been performed for an argon gas. Comparison with the experimental data as well as with the hybrid (particle) and fluid modelling results demonstated good applicability of the proposed model.

Rafatov, I. [Physics Department, Middle East Technical University, Ankara (Turkey); Bogdanov, E. A.; Kudryavtsev, A. A. [Saint Petersburg State University, St. Petersburg (Russian Federation)

2012-09-15

345

Variation of Lap Shear Tensile Strength of Polycarbonate Mild Steel Adhesive Joints with DC Glow Discharge Modified Polycarbonate  

Microsoft Academic Search

It has been observed that the wettability\\/surface energy of polycarbonate (PC) changes with the variation in process parameters, such as discharge power and time of exposure of DC glow discharge. The wettability of the PC surface has been measured by the contact angle measurements of two test liquids, such as water and formamide, by the sessile drop method. The lap

Amrish K. Panwar; S. K. Barthwal; S. Ray

2007-01-01

346

An overview of research using the one atmosphere uniform glow discharge plasma (OAUGDP) for sterilization of surfaces and materials  

Microsoft Academic Search

The medical, food processing, and heating, ventilating, and air conditioning industries are searching for improved pasteurization, disinfection, and sterilization technologies. Candidate techniques must deal with and overcome such problems as thermal sensitivity and destruction by heat, formation of toxic by-products, costs, and inefficiency in performance. We report the results of a plasma source, the One Atmosphere Uniform Glow Discharge Plasma

Thomas C. Montie; Kimberly Kelly-Wintenberg; J. Reece Roth

2000-01-01

347

Hybrid Modeling of a Capacitively Coupled Radio Frequency Glow Discharge in Argon: Combined Monte Carlo and Fluid Model  

Microsoft Academic Search

A hybrid model has been developed for a capacitively coupled rf glow discharge in argon, employed as a spectroscopic source in the field of analytical chemistry. The cell is a rather small cylinder with a very small rf-powered electrode (only 5 mm in diameter). The typical working conditions applied for analytical spectroscopy are a gas pressure of 6 Torr and

Annemie Bogaerts; Renaat Gijbels; WimGoedheer WimGoedheer

1999-01-01

348

Oscillations, Glow and Ignition in Carbon Monoxide Oxidation II. Oscillations in the Gas-Phase Reaction in a Closed System  

Microsoft Academic Search

Carbon monoxide oxidation can show oscillatory behaviour, but, although oscillations in light emission were reported to exist in 1951, they have proved notoriously elusive and irreproducible. The present study is concerned with their nature (glow or explosion) and with the conditions for their occurrence in a closed quartz vessel. Kinetic mechanisms are mentioned here but a full discussion is deferred

J. R. Bond; P. Gray; J. F. Griffiths; S. K. Scott

1982-01-01

349

From the Ground Up II: Sky Glow and Near-Ground Artificial Light Propagation in Flagstaff, Arizona  

Microsoft Academic Search

We present panoramic sky brightness measures in the Johnson V band made at the US Naval Observatory Flagstaff Station. We find that these measures show much less sky glow from Flagstaff than expected using the total light output and unshielded fraction determined recently by Luginbuhl et al. and Garstang's 1991 modeling approach. We suggest the difference arises principally from the

Christian B. Luginbuhl; Dan M. Duriscoe; Chadwick W. Moore; Angela Richman; G. Wesley Lockwood; Donald R. Davis

2009-01-01

350

The One Atmosphere Uniform Glow Discharge Plasma (OAUGDP)—A Platform Technology for the 21st Century  

Microsoft Academic Search

Representatives from many industrial sectors are searching for more economic and ecologically sound technologies to meet regulatory and competitive pressures. Currently, the majority of industrial plasma processing is done with glow discharges at pressures below 10 torr. This tends to limit such applications to high-value items, as a result of the high capital cost of vacuum systems and the production

J. Reece Roth; Sirous Nourgostar; Truman A. Bonds

2007-01-01

351

Glowing Flowers  

NSDL National Science Digital Library

Student teams learn about engineering design of green fluorescent proteins (GFPs) and their use in medical research, including stem cell research. They simulate the use of GFPs by adding fluorescent dye to water and letting a flower or plant to transport the dye throughout its structure. Students apply their knowledge of GFPs to engineering applications in the medical, environmental and space exploration fields. Due to the fluorescing nature of the dye, plant life of any color, light or dark, can be used â unlike dyes that can only be seen in visible light.

Integrated Teaching And Learning Program

352

On the mode switching timescales of pulsar PSR B0329+54  

NASA Astrophysics Data System (ADS)

Chen et al. (2011) found that the durations (timescales) of the normal and abnormal modes of PSR B0329+54 follow a gamma distribution, and constrained the parameters of the distribution function. In this paper, we perform a further analysis on the relationship between the timescales of the two modes. The ratio between the durations of a normal mode and the succeeding abnormal mode is calculated for 54 such pairs. It is found that the cumulative distribution function (CDF) of the ratio is consistent with the CDF obtained by assuming random mode switching, suggesting that the two modes work independently.

Wang, Hong-Guang; Chen, Jian-Ling; Wen, Zhi-Gang; Pi, Fei-Peng

2013-03-01

353

Imaging Modes  

NASA Astrophysics Data System (ADS)

In this chapter, we cover fundamentals of Raman imaging. The different imaging methods, such as point mapping, line scanning and global imaging are described in terms of their advantages and limitations, as well as new imaging modes allowing faster image acquisition. Important definitions of the experiment design, such as spot size, spatial and axial resolution are reviewed. Important concepts enabling to push the limits in terms of spatial resolution are addressed. Finally, basic and more advanced data-processing methods are discussed, as means to separate and eliminate undesirable spectral features. Analysis methods and chemometric tools are introduced, including univariate and multivariate analysis, image and morphological analysis, as well as statistical representation methods. Illustrations are shown with "real-life" samples like pharmaceutical tablets or carbon nanotubes. It concentrates on the empirical `good' practices that can be used in experiment designs.

Lee, Eunah

354

Energy balance of the bulk, Maxwellian electrons in spatially inhomogeneous negative-glow plasmas  

NASA Astrophysics Data System (ADS)

The energy balance of the Maxwellian (bulk) electrons is analyzed in spatially inhomogeneous negative-glow plasmas (NGP). The purpose is to give a comprehensive model which enables the electron temperature in the NGP to be predicted. Since the bulk of the electron distribution function (EDF) in the NGP is Maxwellian, the rates of many important plasma processes (e.g., ambipolar diffusion, recombination, stepwise processes), as well as the plasma potential, are controlled by the electron temperature. Knowledge of the electron temperature is thus of particular importance for such types of plasma. In order to calculate the EDF in the elastic energy range (slow electrons), a spatially inhomogeneous kinetic equation is employed, in which the electron-electron collision integral is fully incorporated. Owing to the complicated (nonlinear integro-differential) form of the electron-electron collision integral, the direct numerical solution of the full kinetic equation represents a difficult task. An efficient way to render the problem tractable consists in breaking the slow electrons up into two distinct groups, namely, the Maxwellian (trapped) and superthermal (untrapped) electrons. The parameters of the Maxwellian EDF can be found from the particle- and energy-balance equations. The superthermal EDF can be found from a reduced kinetic equation. The separation of the electron population into two groups allowed us to obtain an energy-balance equation for the Maxwellian (cold, trapped) electrons, which properly accounts for the most important physical mechanisms, such as heating due to Coulomb collisions with the superthermal (hot, untrapped) electrons. It is shown that the problem of finding the electron temperature in a weakly collisional NGP can be described correctly only at the kinetic level. In this situation, the use of the fluid approximation, in which the electron ensemble is treated in terms of its density and mean energy, results in a physically incorrect energy-balance equation. Furthermore, it is demonstrated that the ``nonlocal'' effects may be critical for the problem of finding the EDF in general, and the electron temperature in particular, so that the ``local'' (kinetic) models may also produce erroneous results. The principal terms in the energy-balance equation are identified, and this equation is simplified to allow a ready solution and implementation into a plasma code. The validity of the proposed model for predicting the electron temperature was confirmed by numerical calculations of the EDF from the full kinetic equation. The results of the paper can be applied to the NGP generated in direct-current glow discharges with planar or hollow cathodes, as well as to negative-glow-like plasmas, such as beam-generated and afterglow (decaying) plasmas.

Arslanbekov, Robert R.; Kudryavtsev, Anatoly A.

1998-11-01

355

Collisional plasmas in Martian dust storms: Application to sustenance and glow emissions  

NASA Astrophysics Data System (ADS)

Mars' dynamic atmosphere displays dust devils and larger, global dust storms. Through models and simulations, these features show large electrostatic fields and it is possible that, in the low pressure Martian atmosphere, they may create an electron avalanche and a collisional plasma due to an increase in electron density with ambient E-field. To show that a plasma is sustained under these conditions, a model of the predicted electric Martian dust storm electron avalanche is created, including electron impact ionization sources and electron loss processes (i.e. dust absorption, system loss, electron dissociation and electron recombination). This new model is called the "Dust Devil Electron Avalanche Model (DDEAM)". These losses have not been included in previous models, which stimulated the objectives of this study, to (a) develop a simple form for the Townsend coefficient, (b) determine the critical E-field where plasma sustenance occurs, (c) determine the electron density and model the continuity equation including losses, and (d) model the developments of a plasma "glow" discharge and Mars methane destruction as functions of E-field. This work enhances the recently- published model by Delory et al. [2006], which considered source terms for electron generation. The DDEAM system of eight one-dimensional differential equations was solved simultaneously for values to characterize the electron density, the densities of constituents ( CO 2 , H 2 O ) and their products ([Special characters omitted.] , CO, O - , OH, H - ) due to electron/molecule interactions in the Martian atmosphere. Values for glow discharge and methane destruction rates were also found. When all losses are included in the electron continuity equation, the electron density grows exponentially with increasing E-field, eventually reaching the equilibrium needed to sustain a plasma. The recombination loss plays the biggest role in stabilizing the system. It is also shown that glow discharges can occur within Martian dust storms, reaching a value of 6×10^21 [Special characters omitted.] with a mean free path of ~32m after traveling 60m down a dust column and should be observable by landed spacecraft. The destruction rate for methane shows an increase by a factor of 10 17 / m 3 s as the E-field increases from 5-25kV/m, which is comparable to the value found in [66].

Jackson, Telana Leilani

356

Endocrine abnormalities in anorexia nervosa.  

PubMed

Anorexia nervosa (AN) is a psychiatric disease associated with notable medical complications and increased mortality. Endocrine abnormalities, including hypogonadotropic hypogonadism, hypercortisolemia, growth hormone resistance and sick euthyroid syndrome, mediate the clinical manifestations of this disease. Alterations in anorexigenic and orexigenic appetite-regulating pathways have also been described. Decreases in fat mass result in adipokine abnormalities. Although most of the endocrine changes that occur in AN represent physiologic adaptation to starvation, some persist after recovery and might contribute to susceptibility to AN recurrence. In this Review, we summarize key endocrine alterations in AN, with a particular focus on the profound bone loss that can occur in this disease. Although AN is increasingly prevalent among boys and men, the disorder predominantly affects girls and women who are, therefore, the focus of this Review. PMID:18542109

Lawson, Elizabeth A; Klibanski, Anne

2008-06-10

357

Coagulation Abnormalities in Critical Illness  

Microsoft Academic Search

\\u000a In critically ill patients coagulation abnormalities often occur. The most pronounced manifestation of these, caused by overwhelming\\u000a activation of the coagulation system, is disseminated intravascular coagulation (DIC) which is also considered to be a component\\u000a of the multiple organ dysfunction syndrome (MODS). There is no generally accepted definition of DIC but recently a working\\u000a definition has been proposed [1]: “DIC

L. G. Thijs

358

Mastoid abnormalities in down syndrome  

Microsoft Academic Search

Hearing loss and otitis media are commonly associated with Down syndrome. Hypoplasia of the mastoids is seen in many affected\\u000a children and sclerosis of mastoid bones is not uncommon in Down syndrome. Awareness and early recognition of mastoid abnormality\\u000a may lead to appropriate and timely therapy, thereby preserving the child’s hearing or compensating for hearing loss; factors\\u000a which are important

R. B. J. Glass; D. K. Yousefzadeh; N. J. Roizen

1989-01-01

359

Liver abnormalities in Turner syndrome  

Microsoft Academic Search

We evaluated whether hepatic abnormalities represent a specific feature in girls with Turner syndrome (TS) or whether they\\u000a are related to an increased susceptibility to hormonal therapies and\\/or other factors. Alanine aminotransferase, aspartate\\u000a aminotransferase and ?-glutamyl transferase were monitored in 70 patients with TS for a mean period of 7.6?±?4.2 years. An\\u000a increase in serum liver enzymes was observed in

M. Salerno; S. Di Maio; N. Gasparini; M. Rizzo; P. Ferri; P. Vajro

1999-01-01

360

Maternal flu and congenital abnormalities  

Microsoft Academic Search

IntroductionRecent case studies following swine flu pandemic show that pregnant woman are more susceptible to flu infection. Various studies have sought to find an association between fetal congenital abnormalities (CAs) and maternal flu infection.MethodologyThe authors performed a review of literature since 1950 in Medline and on the web using keywords ‘Flu’ and ‘CAs’ and collated the results.ResultsIn 2005, Acs et

S Pandey; K Singh

2010-01-01

361

Integrated Mode Management Interface.  

National Technical Information Service (NTIS)

Mode management is the processes of understanding the character and consequences of autoflight modes, planning and selecting the engagement, disengagement and transitions between modes, and anticipating automatic mode transitions made by the autoflight sy...

E. Hutchins

1996-01-01

362

Physics Of The Plasma-Cathode Interface Of Glow Discharge In Oxygen With Aluminium Cathode  

SciTech Connect

Glow discharge in oxygen with aluminium cathode has peculiar characteristics. It works at the product (p{center_dot}L{sub cf}) of gas pressure and the cathode space length, smaller than in other cases, e.g. even Ne/Al discharge. Numerical modelling of electrodynamic structure of the cathode region suggests low multiplication of electron fluxes and consequently high electron emission from the 'oxidised' cathode surface at relatively low anode-cathode voltages U{sub ac}. The above facts explain a low efficiency of the sputtering of 'oxidised' Al-cathodes when determined experimentally. Numerical modelling allows the quantitative explanation of the line emission intensity of oxygen molecules such as its 'linear 'dependence on both gas pressure and discharge current density, J{sub d}. However in the case of line emission of sputtered Al atoms and reflected 'free' O atoms we are able only to draw some qualitative conclusions.

Wronski, Z. [Instutute of Physics, M. Curie Sklodowsha University, 20-031 Lublin (Poland)

2008-03-19

363

Effects of Ion Bombardment on Carbon Nanotube Formation in Strongly Magnetized Glow-Discharge Plasmas  

NASA Astrophysics Data System (ADS)

The effects of ion bombardment on the formation of multi-walled carbon nanotubes (MWNTs) are investigated by controlling radio-frequency (rf) glow-discharge plasmas in strong magnetic fields. When a magnetic field is weak (0.03 T), the MWNTs growing directly on an rf electrode are deformed by the bombardment of the high-energy ions generated by a large sheath electric field in front of the rf electrode. On the other hand, when a strong magnetic field (2 T) is applied, the MWNTs are observed to be well aligned and not to be deformed even under the condition that the rf electrode is negatively biased. These results can be explained by the fact that the ion bombardment energy is reduced despite the existence of the large sheath electric field, which is caused by the magnetization of the ions in the strong magnetic field.

Kaneko, Toshiro; Matsuoka, Hiroki; Hatakeyama, Rikizo; Tohji, Kazuyuki

2005-04-01

364

Spatial relaxation of selective laser perturbations in a glow discharge plasma.  

PubMed

An effect of a nonlocal plasma response caused by local laser radiation exciting atoms in resonant and metastable states is observed in a dc neon glow discharge. Starting at the perturbed position, spatially damped oscillations in the direction of the anode effecting all plasma quantities are created. Depending on the excitation of resonant or metastable atoms, the oscillations are phase-shifted by ?. If the laser excites in particular a cycling transition, no nonlocal plasma response is observed. The relaxation of the plasma is investigated by means of visible light measurements using a line camera in the vicinity of the axial perturbation position. The effect is modeled in terms of nonlocal electron kinetics by solving the spatially inhomogeneous electron Boltzmann equation. PMID:23410442

Brandt, C; Kozakov, R; Testrich, H; Golubovskii, Yu B; Wilke, C

2013-01-07

365

Non-local Effects in a Stratified Glow Discharge With Dusty Particles  

SciTech Connect

The work is aimed to describe non-local effects in the positive column of a low pressure stratified DC glow discharge in argon with dusty particles in a vertical cylindrical discharge tube. The numerical calculations of plasma parameters in the axis of the discharge tube were performed with the help of hybrid model based on the solution of non-local Boltzmann equation for EEDF. Distributions of optical emission from striations were measured experimentally. It is shown that in a stratified positive column the EEDF is not Maxwellian and even non-monotonous. Also, the effect of displacing of optical emission distribution relative to the electric field is shown both by numerical simulation and experimental measurements.

Sukhinin, G. I. [Institute of Thermophysics SB RAS, Lavrentyev Ave., 1, Novosibirsk, 630090 (Russian Federation); Novosibirsk State University, Pirogova Str., 2, Novosibirsk, 630090 (Russian Federation); Fedoseev, A. V. [Institute of Thermophysics SB RAS, Lavrentyev Ave., 1, Novosibirsk, 630090 (Russian Federation); Ramazanov, T. S.; Amangaliyeva, R. Zh.; Dosbolayev, M. K.; Jumabekov, A. N. [Institute of Experimental and Theoretical Physics, Al Farabi Kazakh National University, Tole Bi, 96a, Almaty, 050012 (Kazakhstan)

2008-09-07

366

The recovery of glow-plasma structure in atmospheric radio frequency microplasmas at very small gaps  

SciTech Connect

In atmospheric radio frequency discharges at 13.56 MHz, with the electrode gap reduced, the sheath region eventually occupies a main portion of the electrode spacing and the bulk plasma region is significantly compressed. The computational results in this letter based on a one-dimensional fluid model show that by increasing the excitation frequency over 13.56 MHz, the traditional glow-plasma structure could gradually recover even at very small sizes with a well defined quasineutral plasma region, and the electron density is improved but the electric fields in sheath region are reduced. This study indicates that the excitation frequency can be used to modulate the discharge structure and then tailor the plasma-surface interaction in atmospheric microplasmas.

Zhang Yuantao [Shandong Provincial Key Lab of UHV Technology and Gas Discharge Physics, School of Electrical Engineering, Shandong University, Jinan 250061, Shandong Province (China); Shang Wanli [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, Sichuan Province (China)

2011-11-15

367

Anomalous secondary electron emission of metallic surfaces exposed to a Glow Discharge plasma  

NASA Astrophysics Data System (ADS)

Secondary electron emission (SEE) yields, ?, of Li, stainless steel (SS) and W surfaces immersed in a He Direct Current Glow Discharge (dc-GD) Plasma have been calculated from the experimental I-V curves as a function of electron mean energy. The data obtained showed that ?Li > ?SS > ?W. Line emission ratios 728/706 of excited He and Langmuir probe measurements provide a clear evidence of the presence of a suprathermal electron tail responsible for the observed SEE.The results show that SEE is well correlated with the anomalous extra current component found in the I-V curves. The resulting value of ?Li is significantly higher than its theoretical value suggesting a possible synergetic effect of the ion bombardment in the SEE of lithium. The effect of Li surface oxidation has also been addressed, leading to a substantial decrease of both, sputtering yield and SEE yield of Li with higher oxygen content.

Oyarzabal, E.; Martín-Rojo, A. B.; Ferreira, J. A.; Tafalla, D.; Tabarés, F. L.

2013-07-01

368

Attenuation of microwaves propagating through parallel-plate helium glow discharge at atmospheric pressure  

SciTech Connect

The experimental study of microwave-plasma interaction has been performed to demonstrate the transmission and attenuation of microwaves in atmospheric pressure glow discharge plasma. The cold-collisional plasma produced at atmospheric pressure can absorb the microwave energy because of its complex dielectric constant. The microwave of 10 GHz frequency was launched into the plasma and attenuation was measured as a function of electron plasma density, plasma thickness, electron-neutral collision frequency, etc. It was observed that the attenuation significantly depends on electron plasma density and thickness. The microwave attenuation measurement was also used as a diagnostic to estimate electron plasma density. It was validated by optical emission spectroscopic measurements with helium line intensity ratio method. Both the methods show good agreement.

Srivastava, A. K.; Prasad, G.; Atrey, P. K.; Kumar, Vinay [Institute for Plasma Research, Bhat, Near Indira Bridge, Gandhinagar, Gujarat 382428 (India)

2008-02-01

369

Drag force reduction on an airfoil via glow discharge plasma-based control  

NASA Astrophysics Data System (ADS)

Glow discharge plasma on a solid surface will result in a body force which modifies the pressure distribution along the flow boundary layer, and consequently re-attaches the separated flows for reduction of a hydrodynamic drag force. In this paper, we investigate the discharge performance of various plasma-actuated electrodes in terms of their arrangements and structures. The resulting optimal configuration for the electrode separation distance was used to develop a flexible actuated panel to be mounted onto a NACA 0015 airfoil. Both uniphase and eight-phase power inputs were used to examine its drag reduction performance at various attack angles and flow velocities. Numerical calculations were also performed by including an electrostatic body force in the hydrodynamic equation. Good agreement were found between the numerical and experiment results.

Fu, X.; Li, Y.; Li, B.; Kwok, D. Y.

2009-04-01

370

Large-volume and low-frequency atmospheric glow discharges without dielectric barrier  

NASA Astrophysics Data System (ADS)

It is widely believed that, at low frequencies of 1-100 kHz, the generation of atmospheric pressure glow discharges (APGD) requires a dielectric barrier added to at least one electrode. This letter reports the experimental observation of a uniform and stable APGD generated between two bare electrodes without a dielectric barrier over a wide frequency range from 20 kHz to 260 kHz. Below 70 kHz, it is shown that preionization in the rising phase of the applied voltage is important and plasma generation occurs in the voltage-falling phase. Mechanism of barrier-free APGD is found to be different from both atmospheric dielectric-barrier discharges and radio-frequency APGD.

Shi, J. J.; Kong, M. G.

2005-02-01

371

The Role of Fe(II) in the Contact Glow Discharge Electrolysis  

NASA Astrophysics Data System (ADS)

In this paper, we use methyl violet as a model organic substrate in wastewater to study the effect of Fe(II) ion on the contact glow discharge electrolysis (CGDE). The decoloration rate and the COD (Chemical Oxygen Demand) value have been examined. It is found that the presence of Fe(II) ion can accelerate obviously the degradation of methyl violet, because it reacts with H2O2 in the CGDE process to yield hydroxyl radical, just acting as a Fenton-like reagent. Moreover, the optimal conditions for decoloring methyl violet were obtained, by means of an orthogonal experiment, to be [Fe2+] =1× 10-3 mol/L, applied voltage of 700 V of and pH = 9.0.

Gao, Jinzhang; Guo, Xiao; Ma, Dongping; Yang, Wu

2007-08-01

372

PREPARATION OF CU-DOPED GLOW DISCHARGE POLYMER COATINGS FOR ICF APPLICATIONS  

SciTech Connect

OAK-B135 Copper doped polymer shells can provide a very useful diagnostic for fast ignition experiments currently being performed at various laboratories around the world. The low concentration copper dopant acts as an efficient x-ray source providing information on the physics of fast ignition. They have developed copper doped glow discharge (GDP) coatings suitable for such purposes. Copper acetylacetonate (CuAcAC), a solid at room temperature, was used in a heated jacket as the dopant source. They used this technique to fabricate thin ({approx} 5-7 {micro}m) GDP shells doped with {approx} 1 at% copper through the depolymerizable mandrel process for fast ignition experiments. The details of the experimental set up and the range and limitations of the technique are discussed.

NIKROO,A; CASTILLO,E; HILL,D.W; GREENWOOD,A.L.

2003-06-01

373

PROGRESS IN 2 mm GLOW DISCHARGE POLYMER MANDREL DEVELOPMENT FOR NIF  

SciTech Connect

OAK-B135 All planned National Ignition Facility (NIF) capsule targets except machined beryllium require a glow discharge polymer (GDP) mandrel upon which the albator is applied. This mandrel, {approx} 2 mm in diameter, must at least meet if not exceed the symmetry and surface finish requirements of the final capsule. Such mandrels are currently produced by the three-step depolymerizable mandrel technique. The quality of the final mandrel depends upon precise optimization and execution of each of the three steps. They had shown previously that fabrication of a mandrel which met the symmetry and surface finish requirements was feasible using this technique. In this paper they will discuss recent progress towards converting this process into a high yield, production scale process.

NIKROO,A; BOUSQUET,J; COOK,R; McQUILLAN,B.W; PAGUIO,R; TAKAGI,M

2003-06-01

374

Progress in 2 mm Glow Discharge Polymer Mandrel Development for NIF  

SciTech Connect

All planned National Ignition Facility (NIF) capsule targets except machined beryllium require a glow discharge polymer (GDP) mandrel upon which the ablator is applied. This mandrel, {approx}2 mm in diameter, must at least meet if not exceed the symmetry and surface finish requirements of the final capsule. Such mandrels are currently produced by the three-step depolymerizable mandrel technique. The quality of the final mandrel depends upon precise optimization and execution of each of the three steps. We had shown previously that fabrication of a mandrel which met the symmetry and surface finish requirements was feasible using this technique. In this paper we will discuss recent progress towards converting this process into a high yield, production scale process.

Nikroo, A. [General Atomics (United States); Bousquet, J. [San Diego State University (United States); Cook, R. [Lawrence Livermore National Laboratory (United States); McQuillan, B.W. [General Atomics (United States); Paguio, R. [General Atomics (United States); Takagi, M. [Lawrence Livermore National Laboratory (United States)

2004-03-15

375

Preparation of Cu-Doped Glow Discharge Polymer Coatings for ICF Applications  

SciTech Connect

Copper doped polymer shells can provide a very useful diagnostic for fast ignition experiments currently being performed at various laboratories around the world. The low concentration copper dopant acts as an efficient x-ray source providing information on the physics of fast ignition. We have developed copper doped glow discharge (GDP) coatings suitable for such purposes. Copper acetylacetonate (CuAcAC), a solid at room temperature, was used in a heated jacket as the dopant source. We used this technique to fabricate thin ({approx}5-7 {mu}m) GDP shells doped with {approx}1 at % copper through the depolymerizable mandrel process for fast ignition experiments. The details of the experimental set up and the range and limitations of the technique are discussed.

Nikroo, A.; Castillo, E.; Hill, D.; Greenwood, A.L. [General Atomics (United States)

2004-03-15

376

Anodization of aluminum and silicon in plasma of a non-self-sustained glow discharge  

SciTech Connect

The results of anodization of aluminum and silicon in an oxygen plasma are presented. The plasma was generated by a non-self-sustained glow discharge with a hollow cathode excited by an electron beam at the oxygen pressure of 20 Pa. The density of the current flowing through the anodized specimen did not exceed 1.5 mA/cm{sup 2}, and its temperature was 200-250 Degree-Sign C. Continuous Al{sub 2}O{sub 3} and SiO{sub 2} films were formed on the aluminum and silicon surfaces. The growth rate of the oxide layers was 150-200 nm/h for Al{sub 2}O{sub 3} and 400-800 nm/h for SiO{sub 2}.

Burachevsky, Yu. A., E-mail: office@tusur.ru; Burdovitsin, V. A.; Oks, E. M. [Tomsk State University of Control Systems and Radioelectronics (Russian Federation)

2011-12-15

377

On the Shock Wave Visualization in Hypersonic Flows Using Glow Discharge  

NASA Astrophysics Data System (ADS)

When a glow discharge is generated across a shock wave in hypersonic flows, the wave is visualized as a nonluminous layer in a uniformly luminous positive column. In this report, a tentative theory that explains why the wave is visualized as stated above is proposed. The idea is as described below. A space charge layer produced due to discontinuity of electron density Ne at the wave lets itself keep off the electrons that is fast thermally enough to excite molecules to radiative states. Consequently the nonluminous layer is observed along the wave surface. To verify the idea, an analysis on two regions upstream and downstream the wave in the positive column is carried out applying Schottky theory. The analysis shows that the electron temperature, the electric field, and the Ne change across the wave discontinuously. The discontinuity of the Ne causes the diffusion of the electrons, and consequently the space charge layer is produced.

Itoh, Hajime

378

Degradation of m-dihydroxybenzene by contact glow discharge electrolysis in aqueous  

NASA Astrophysics Data System (ADS)

This paper reported the degradation of m-dihydroxybenzene aqueous solution with contact Glow Discharge Electrolysis. The rate of degradation in different conditions such as pH, H2O2, Fe2+, methanol, and other affecting factors were studied. The results showed that there is faster removal rate when the solution is in a relatively higher acidity; H2O2 can improve the efficiency rate. Fe2+ can promote reaction, but radical elimination agent of methanol will decrease the rate of the reaction. On the basis of analyzing the ultraviolet (UV) spectra of the solution and the intermediate products from High Performance Liquid Chromatography-Mass Spectrum (HPLC-MS), reaction pathway was proposed.

Gai, Ke; Qi, Huili; Ma, Dongping; Wang, Chunlin

2013-03-01

379

Anode glow discharge plasma treatment enhances calcium phosphate adsorption onto titanium plates.  

PubMed

Glow discharge plasma (GDP) supplied to a cathode (GDP-) has been applied for cleaning, surface activating, and sterilizing biomaterials, because the kinetic energy in the case of the GDP- is larger than that supplied to the anode (GDP+). However, no comparison between GDP+ and GDP- has been reported. In this study, a titanium surface pre-treated with GDP+ and GDP- was characterized by x-ray photoelectron spectroscopy (XPS). In addition, the wettability of the titanium surface was measured with and without GDP. Furthermore, XPS characterized the adsorption of inorganic ions on titanium surfaces with and without GDP and immersed in an electrolyte solution. The findings suggested that GDP+ enhances calcium phosphate nucleation, due to the accumulation of electrons. In addition, calcium phosphate was not nucleated on the specimen with GDP-. We conclude that GDP+ is more suitable for biomineralization on titanium. PMID:12454099

Shibata, Y; Miyazaki, T

2002-12-01

380

Plasma sheath physics and dose uniformity in enhanced glow discharge plasma immersion ion implantation and deposition  

SciTech Connect

Based on the multiple-grid particle-in-cell code, an advanced simulation model is established to study the sheath physics and dose uniformity along the sample stage in order to provide the theoretical basis for further improvement of enhanced glow discharge plasma immersion ion implantation and deposition. At t=7.0 mus, the expansion of the sheath in the horizontal direction is hindered by the dielectric cage. The electron focusing effect is demonstrated by this model. Most of the ions at the inside wall of the cage are implanted into the edge of the sample stage and a relatively uniform ion fluence distribution with a large peak is observed at the end. Compared to the results obtained from the previous model, a higher implant fluence and larger area of uniformity are disclosed.

Li Liuhe; Li Jianhui [Department 702, School of Mechanical and Automation Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China); Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong); Kwok, Dixon T. K.; Chu, Paul K. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong); Wang Zhuo [Department 702, School of Mechanical and Automation Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China)

2009-07-01

381

Design and construction of uniform glow discharge plasma system operating under atmospheric condition  

SciTech Connect

The design of a uniform glow discharge plasma system operating without vacuum is presented. A full-bridge switching circuit was used to switch the transformers. The primary windings of transformers were connected in parallel, but in opposite phase to double the output voltage. Theoretically, 20 000 V{sub pp} was obtained. Rectangle copper electrodes were used, and placed parallel to each other. To prevent the spark production that is, to obtain uniformity, two 2 mm Teflon sheets were glued to the electrodes. However, it was observed that the operating frequency also affected the uniformity. For the system presented here, the frequency at which more uniformity was obtained was found to be 14 kHz.

Kocum, C.; Ayhan, H. [Biomedical Engineering Department, Baskent University, Ankara 06530 (Turkey); Chemistry Department, Biochemistry Division, Mugla University, Faculty of Science, Koetekli, 48170 Mugla (Turkey)

2007-06-15

382

Oxidative Degradation of 4-chlorophenol in Aqueous Induced by Plasma with Submersed Glow Discharge Electrolysis  

NASA Astrophysics Data System (ADS)

The oxidative degradation of 4-chlorophenol (4-CP) in aqueous solution induced by plasma with submersed glow discharge has been investigated. The concentration of 4-CP and the reaction intermediates were determined by high performance liquid chromatography (HPLC). Various influencing factors such as the initial pH, the concentration of 4-CP and the catalytic action of Fe2+ were examined. The results indicate that 4-CP is eventually degraded into inorganic ion, dioxide carbon and water. The attack of hydroxyl radicals on the benzene rings of 4-CP in the initial stage of oxidative reactions is presumed to be a key step. They also suggest that the reaction is of a pseudo-first order kinetic reaction and the proposed method is an efficient way for the 4-CP degradation.

Pu, Lumei; Gao, Jinzhang; Yang, Wu; Li, Yan; Yu, Jie; Huang, Dongling

2005-10-01

383

Experimental And Theoretical Studies On The Characteristics Of Low-Pressure Glow Discharge With Liquid Cathode  

NASA Astrophysics Data System (ADS)

The characteristics of low-pressure air glow discharge with liquid cathode (electrolytic cathode low-pressure discharge, ELCLPD) has been investigated. Distilled water was utilized as a cathode. The electric field strength, gas temperature as well as emission intensity of some bands of N2(C3?u?B3 ?g) were measured at pressure from 76 to 760 torr at fixed discharge current of 40 mA. Based upon these data, the reduced electric field strength, E/N, effective vibrational temperatures for N2(C3?u, X1Sg+) and rotational temperatures for N2(X1Sg+) were investigated. The electron energy distribution function (EEDF) and some electron parameters (average energy, electron density) were obtained on the base of numerical solution of the Boltzmann kinetic equation.

Shutov, D.; Ivanov, A.; Smirnov, S.; Rybkin v.

2010-07-01

384

Amplitude equation at ionization instability and the onset of turbulence in a neon glow discharge  

NASA Astrophysics Data System (ADS)

We investigate the bifurcations of ionization waves from the homogeneous stationary state of the positive column in a neon glow discharge. In the weak nonlinear region the wave dynamics is approximated by an amplitude equation of the Ginzburg-Landau type with complex coefficients and an additional integral term. This nonlocal term describes the influence of the external circuit on the ionization waves. Conditions are derived for the band of Eckhaus stable wave solutions. The dependence of the complex coefficients on the plasma parameters is discussed and used to classify the solution manifold of the amplitude equation. Raising the gas pressure from 130 Pa up to 720 Pa, the intermittency, bichaos, and amplitude turbulence regions are visited successively. Some of these theoretical results are supported by numerical calculations for selected parameter values.

Bruhn, B.; Koch, B.-P.; Jonas, P.

1998-09-01

385

Measurement of electron temperature in glow discharge in transverse magnetic field by spectroscopic method  

NASA Astrophysics Data System (ADS)

The electron temperature in the positive column of a glow discharge in hydrogen and helium as a function of the transverse magnetic field in the range of 0 to 1000 G has been obtained by measuring the intensities of two spectral lines having the same lower level. Since the electron number density in the column is of the order of 10 to the 10th/cu cm the semicorona model suitably modified has been used to calculate the plasma electron temperature in a magnetic field. For lower values of the field the variation of the electron temperature with the field can be represented by an expression deduced by Sen and Gupta following Beckman's theory. The electron energy distribution in a transverse field can thus be assumed to be nearly Maxwellian.

Sadhya, S. K.; Sen, S. N.

1980-07-01

386

In situ reactive glow discharge cleaning of x-ray optical surfaces  

SciTech Connect

We report the first implementation of an in situ glow discharge cleaning procedure for the removal of carbon contamination from x-ray optical surfaces. In situ cleaning obviates the need for the time-consuming and costly process of element removal, cleaning or repolishing, remounting, and realignment usually necessary to restore x-ray optics to their original condition. The apparatus required is quite simple and can easily be fitted to most existing UHV (ultrahigh vacuum) mirror boxes or monochromators. Results with several monochromators at the Brookhaven National Labs National Synchrotron Light Source (NSLS) show that better than original performance can be obtained at the carbon K edge, since the elements are not exposed to atmosphere after in situ cleaning and do not accumulate the adventitious carbon layer associated with more traditional methods. Possible improvements and extensions of the technique are also described.

Johnson, E.D.; Hulbert, S.L.; Garrett, R.F.; Williams, G.P.; Knotek, M.L.

1987-06-01

387

Retarding field energy analyzer for the characterization of negative glow sheet plasmas in a magnetic field  

SciTech Connect

A retarding field energy analyzer has been developed for diagnosing 300 {mu}s duration, 60 cm{times}60 cm negative glow, sheet plasmas immersed in a 150{endash}250 G axial magnetic field. The electron density in these 4.5 kV, 13 A, 120 mTorr discharges in air and other gases, is high enough to reflect {ital X}-band microwaves. The presence of the magnetic field makes the suppression of secondary electrons from the Faraday collector surface more difficult. The approach taken here is to bias the entire collection circuit and the amplifiers 90 V positive with respect to the data acquisition room. The differentially pumped analyzer is designed to accept electrons with a large range of perpendicular velocities, and it measures the parallel velocity distribution function of the discharge electrons entering a 0.64-mm-diam hole in the anode plate. It gives valuable information about the energy spectrum of the energetic beam electrons emitted from the cathode, and the effect of energy loss and scattering processes on this propagating beam component. Additionally, since the analyzer sampling hole is offset from the anode-cathode axis, the current density profile can be measured for different bias voltages on the retarding grid, by rotating the linear cathode about the vertical anode-cathode axis. These profiles give the sheet thickness for the beam and plasma components of the negative glow discharge. It also gives useful information about the scattering induced beam spreading and its effects on the plasma sheet thickness and electron density. {copyright} {ital 1996 American Institute of Physics.}

Mathew, J.; Meger, R.A.; Fernsler, R.F. [Plasma Physics Division, Naval Research Laboratory, Washington, DC 20375-5346 (United States); Gregor, J.A. [Institute for Plasma Physics, University of Maryland, College Park, Maryland 20742 (United States)

1996-08-01

388

Radio-frequency powered glow discharge device and method with high voltage interface  

DOEpatents

A high voltage accelerating potential, which is supplied by a high voltage direct current power supply, is applied to the electrically conducting interior wall of an RF powered glow discharge cell. The RF power supply desirably is electrically grounded, and the conductor carrying the RF power to the sample held by the probe is desirably shielded completely excepting only the conductor's terminal point of contact with the sample. The high voltage DC accelerating potential is not supplied to the sample. A high voltage capacitance is electrically connected in series between the sample on the one hand and the RF power supply and an impedance matching network on the other hand. The high voltage capacitance isolates the high DC voltage from the RF electronics, while the RF potential is passed across the high voltage capacitance to the plasma. An inductor protects at least the RF power supply, and desirably the impedance matching network as well, from a short that might occur across the high voltage capacitance. The discharge cell and the probe which holds the sample are configured and disposed to prevent the probe's components, which are maintained at ground potential, from bridging between the relatively low vacuum region in communication with the glow discharge maintained within the cell on the one hand, and the relatively high vacuum region surrounding the probe and cell on the other hand. The probe and cell also are configured and disposed to prevent the probe's components from electrically shorting the cell's components.

Duckworth, Douglas C. (Knoxville, TN); Marcus, R. Kenneth (Clemson, SC); Donohue, David L. (Vienna, AT); Lewis, Trousdale A. (Oak Ridge, TN)

1994-01-01

389

[O] [H] functionalization on carbon nanotube using (O2-H2) gas mixture DC glow discharge  

NASA Astrophysics Data System (ADS)

The [O] [H] functionalization of carbon nanotube (CNT) was studied using oxygen-hydrogen (O2-H2) gas mixture direct current (DC) glow discharge plasma technique for cathode/CNT-anode separation of 0.10 ± 0.01 cm. O2 and H2 were fixed at flowrate of 10.0 ml/min in order to obtain gas mixture ratio of 1:1. During the (O2-H2) gas mixture DC glow discharge, current-voltage ( I- V) characteristic of gaseous species studied for various settings of gas pressures 1, 2, 3 and 4 mbar. The voltage at gap between cathode/CNT and anode, a breakdown voltage, was identified as "functionalization voltage" ( V func). V func was noticed responsible for functionalization of functional groups on sidewall of CNT. The V func were recorded as 796, 707, 594, and 663 V for gas pressures of 1, 2, 3 and 4 mbar, respectively. The co-relation between V func and gas pressure was identified as linear relationship. But a voltage obtained due to the CNT/Cathode fall shows exponential relationship with the gas pressures. The possibility of [O] [H] functionalization was proved using Fourier transmission infra-red (FTIR) spectroscopy. Hydroxyl (-OH), carboxyl (-COOH), and carbonyl (-C=O) functional groups were identical as identified in the FTIR spectra. The field emission scanning electron microscope images show significant changes in the morphology of CNT which proves that the DC gas discharge plasma is a possible technique for [O] [H] functionalization on the sidewall of CNT.

Thandavan, Tamil Many K.; Wong, Chiow San; Gani, Siti Meriam Abdul; Nor, Roslan Md

2012-03-01

390

Influence of the water surface on the glow-to-spark transition in a metal-pin-to-water electrode system  

NASA Astrophysics Data System (ADS)

The glow-to-spark transition in a pin-to-water anode electrode system is investigated and compared with a pin-to-metal-plate system with 20 ns time resolution by fast imaging and corresponding current and voltage measurements. A contraction of the anode spot and cathode spot of the glow is observed in the pin-metal-plate system leading to a narrow filamentary spark, while the anode spot on the water anode electrode remains diffuse. In the latter case only a significant radial constriction of the glow in the bulk and near the metal cathode of the discharge gap is observed which causes a broadening of the spark near the water anode. Constriction of this broadened spark channel occurs several 100 ns after spark ignition. Additionally, the influence of the conductivity of the liquid electrode on the glow-to-spark transition is investigated.

Bruggeman, Peter; Guns, Peter; Degroote, Joris; Vierendeels, Jan; Leys, Christophe

2008-11-01

391

Performance and Economics of Catalytic Glow Plugs and Shields in Direct Injection Natural Gas Engines for the Next Generation Natural Gas Vehicle Program: Final Report  

SciTech Connect

Subcontractor report details work done by TIAX and Westport to test and perform cost analysis for catalytic glow plugs and shields for direct-injection natural gas engines for the Next Generation Natural Gas Vehicle Program.

Mello, J. P.; Bezaire, D.; Sriramulu, S.; Weber, R.

2003-08-01

392

Preparacion por descarga luminiscente y caracterizacion electrooptica de aleaciones de silicio amorfo para celulas solares. (Glow discharge preparation and electrooptical characterisation of amorphous silicon alloys for solar cells).  

National Technical Information Service (NTIS)

A study is presented, focused on the preparation and characterisation of hydrogenated amorphous silicon alloy thin films for their application as p type window layers in pin silicon solar cells. The preparation technique used was radio frequency glow disc...

J. Carabe

1990-01-01

393

Reply to comments on—The effect of the heating rate on the characteristics of some experimental thermoluminescence glow curves by Rasheedy et al  

NASA Astrophysics Data System (ADS)

In the paper by Kumar et al, some criticism is advanced to the analysis of the glow curves measured under different heating rates in the laboratory, which appeared in our recent paper [M.S. Rasheedy and E.M. Zahran, 2006 Phys. Scr., 73 98-102]. According to this analysis the area under the glow curve is conserved in both TL-time plots and TL-temperature plots. On the contrary, Kumar et al supposed increase of the area under the glow curve with increasing the heating rate in the case of TL-temperature plots. Since this criticism discredits a physical reason for conservation of the area under the glow curves due to conservation of the imparted dose at different heating rates, a reply appears to be timely.

Rasheedy, M. S.; Zahran, E. M.

2006-08-01

394

Pathology Case Study: Sensory Abnormalities  

NSDL National Science Digital Library

The Department of Pathology at the University of Pittsburgh Medical Center has compiled a wide range of pathology case studies to aid students and instructors in the medical/health science field. This particular case focuses on a 30-year-old man with a history of focal numbness, bladder and bowel dysfunction, and progressive sensory abnormalities. The patientâÂÂs history, images from an MRI, microscopic images of a specimen collected during his laminectomy, and final diagnosis are provided in this case for your review. Students will find this resource especially helpful, as it provides experience with patient history, lab results, and diagnostics.

Smith, Sharyn; Lownie, Steven P.; Duggal, Neil; Hammond, Robert R.

2007-12-10

395

Evaluation of abnormal liver function tests  

PubMed Central

Interpretation of abnormalities in liver function tests is a common problem faced by clinicians. This has become more common with the introduction of automated routine laboratory testing. Not all persons with one or more abnormalities in these tests actually have liver disease. The various biochemical tests, their pathophysiology, and an approach to the interpretation of abnormal liver function tests are discussed in this review.

Limdi, J; Hyde, G

2003-01-01

396

Neurobiological trait abnormalities in bipolar disorder  

Microsoft Academic Search

Dissecting trait neurobiological abnormalities in bipolar disorder (BD) from those characterizing episodes of mood disturbance will help elucidate the aetiopathogenesis of the illness. This selective review highlights the immunological, neuroendocrinological, molecular biological and neuroimaging abnormalities characteristic of BD, with a focus on those likely to reflect trait abnormalities by virtue of their presence in euthymic patients or in unaffected relatives

C Langan; C McDonald

2009-01-01

397

Research on secondary penetrating radiation when interacting x-ray beams from cathode of high-current glow discharge with targets made of various materials  

NASA Astrophysics Data System (ADS)

The results of experimental research into characteristics of secondary penetrating radiation occurring when interacting primary X-ray beams from a solid-state cathode medium with targets made of various materials are reported. The experiments were carried out in a high-current glow discharge device with H2, D2 Kr, Xe gases and cathode samples made of Al, Sc, Ti, Ni, Nb, Zr, Mo, Pd, Ta, W, and Pt. The targets are shields made of various materials foil (Al, Ti, Ni, Zr, Yb, Ta, and W) with thickness of 10 - 30 ?m and of 1- 3 mm. They were mounted at a distance of 21 and 70 cm from the cathode. In these experiments recording of the time radiation spectrums was carried out just before and after discharge current pulses (no discharge current). It was shown that the secondary radiation consisted of fast electrons. The secondary radiation of two types was observed. (1) The emission with a continuous temporal spectrum in the form of separate bursts with intensity up to 106 fast electrons a burst. (2) The emission with a discrete temporal spectrum and emission rate up to 109 fast electrons a burst. A third type of the penetrating radiation was observed as well. This type was recorded directly by the photomultiplier placed behind of the target without the scintillator. The abnormal high penetrating ability of this radiation type requires additional research to explain. The obtained results show that creating optically active medium with long-living metastable levels with the energy of 1.0-3.0 keV and more is possible in the solid state.

Karabut, Alexander B.; Gavritenkov, Dmitriy V.

2004-10-01

398

LONG-TERM MONITORING OF MODE SWITCHING FOR PSR B0329+54  

SciTech Connect

The mode-switching phenomenon of PSR B0329+54 is investigated based on the long-term monitoring from 2003 September to 2009 April made with the Urumqi 25 m radio telescope at 1540 MHz. At that frequency, the change of relative intensity between the leading and trailing components is the predominant feature of mode switching. The intensity ratios between the leading and trailing components are measured for the individual profiles averaged over a few minutes. It is found that the ratios follow normal distributions, where the abnormal mode has a greater typical width than the normal mode, indicating that the abnormal mode is less stable than the normal mode. Our data show that 84.9% of the time for PSR B0329+54 was in the normal mode and 15.1% was in the abnormal mode. From the two passages of eight-day quasi-continuous observations in 2004, supplemented by the daily data observed with the 15 m telescope at 610 MHz at Jodrell Bank Observatory, the intrinsic distributions of mode timescales are constrained with the Bayesian inference method. It is found that the gamma distribution with the shape parameter slightly smaller than 1 is favored over the normal, log-normal, and Pareto distributions. The optimal scale parameters of the gamma distribution are 31.5 minutes for the abnormal mode and 154 minutes for the normal mode. The shape parameters have very similar values, i.e., 0.75{sup +0.22}{sub -0.17} for the normal mode and 0.84{sup +0.28}{sub -0.22} for the abnormal mode, indicating that the physical mechanisms in both modes may be the same. No long-term modulation of the relative intensity ratios was found for either mode, suggesting that the mode switching was stable. The intrinsic timescale distributions, constrained for this pulsar for the first time, provide valuable information to understand the physics of mode switching.

Chen, J. L.; Wang, N.; Liu, Z. Y.; Yuan, J. P. [Xinjiang Astronomical Observatory, 150, Science-1 Street, Urumqi, Xinjiang, 830011 (China); Wang, H. G. [Center for Astrophysics, Guangzhou University, Guangzhou 510006 (China); Lyne, A. [University of Manchester, Jodrell Bank (United Kingdom); Jessner, A.; Kramer, M., E-mail: hgwang@gzhu.edu.cn [Max-Planck Institute for Radio Astronomy, Bonn 53121 (Germany)

2011-11-01

399

Disorders caused by chromosome abnormalities  

PubMed Central

Many human genetic disorders result from unbalanced chromosome abnormalities, in which there is a net gain or loss of genetic material. Such imbalances often disrupt large numbers of dosage-sensitive, developmentally important genes and result in specific and complex phenotypes. Alternately, some chromosomal syndromes may be caused by a deletion or duplication of a single gene with pleiotropic effects. Traditionally, chromosome abnormalities were identified by visual inspection of the chromosomes under a microscope. The use of molecular cytogenetic technologies, such as fluorescence in situ hybridization and microarrays, has allowed for the identification of cryptic or submicroscopic imbalances, which are not visible under the light microscope. Microarrays have allowed for the identification of numerous new syndromes through a genotype-first approach in which patients with the same or overlapping genomic alterations are identified and then the phenotypes are described. Because many chromosomal alterations are large and encompass numerous genes, the ascertainment of individuals with overlapping deletions and varying clinical features may allow researchers to narrow the region in which to search for candidate genes.

Theisen, Aaron; Shaffer, Lisa G

2010-01-01

400

RECENT PROGRESS IN FABRICATION OF HIGH-STRENGTH GLOW DISCHARGE POLYMER SHELLS BY OPTIMIZATION OF COATING PARAMETERS  

SciTech Connect

OAK A271 RECENT PROGRESS IN FABRICATION OF HIGH-STRENGTH GLOW DISCHARGE POLYMER SHELLS BY OPTIMIZATION OF COATING PARAMETERS. In this paper, the authors report the progress they have made in fabrication of high-strength thin-walled glow discharge polymer (GDP) shells for cryogenic experiments at OMEGA. They have investigated a number of different parameters involved in making such shells. Optimization of hydrogen to hydrocarbon precursor flow has been observed to be critical in obtaining strong shells. They can routinely make high-strength shells of OMEGA size (900 {micro}m in diameter) with thicknesses in the range of 1.0 to 1.5 {micro}m. The permeabilities of these shells to various gases have been found to be as much as three times higher than those of lower strength shells. Run to run variability and other batch statistics are discussed.

NIKROO, A; CZECHOWICZ, DG; CASTILLO, ER; PONTELANDOLFO, JM

2002-04-01

401

Dependence of the piezoactivity of zinc oxide films on the conditions of synthesis in critical regimes of glow discharge  

NASA Astrophysics Data System (ADS)

The influence of the gas pressure in a magnetron sputtering system on the efficiency of volume hypersound generation in the synthesized ZnO films has been experimentally studied at pressures close to the transition from glow discharge to Townsend regime, whereby the ion and electron mean free path length increases and a drift component appears in the flux of deposited particles. It is established that the efficiency of hypersound generation (at a frequency above 1 GHz) in ZnO films deposited under these conditions increases. Based on a comparison to the properties of films deposited in a classical diffuse glow discharge, this result is explained by a lower nucleation texture and higher density of the films grown in a critical regime.

Aleksandrov, V. A.; Veselov, A. G.; Kiryasova, O. A.; Serdobintsev, A. A.

2012-09-01

402

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

NASA Astrophysics Data System (ADS)

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

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

2010-11-01

403

Study of the glow dynamics in a laser-produced plasma jet expanding across the magnetic field  

SciTech Connect

Results are presented from experimental studies of the glow dynamics of a plasma jet generated during the irradiation of a plane aluminum target by an iodine laser pulse with the wavelength 1.315 {mu}m. The laser pulse energy was 330-480 J, the pulse duration was 0.5 ns, and the focal spot diameter was 3 mm, the laser intensity on the target surface being {approx}10{sup 13} W/cm{sup 2}. The jet expanded across an external magnetic field with the strength {approx}1 kOe. The residual air pressure in the vacuum chamber was {approx}10{sup -5} Torr. The spatiotemporal behavior of the jet glow was investigated using a nine-frame camera in two mutually perpendicular directions (along and across the magnetic field). The results of measurements indicate azimuthal asymmetry of the jet expansion.

Bessarab, A. V.; Bondarenko, G. A.; Garanin, S. G.; Zhidkov, N. V.; Nikitin, I. N.; Starodubtsev, V. A.; Sungatullin, R. R. [All-Russia Research Institute of Experimental Physics, Russian Federal Nuclear Center (Russian Federation)

2011-09-15

404

Multi-pin-to-plate atmospheric glow discharge for the removal of volatile organic compounds in waste air  

Microsoft Academic Search

A DC-excited atmospheric pressure glow discharge in a multi-pin-to-plate electrode configuration is applied to the removal of trichloroethylene (TCE) in air. A removal fraction of up to 47% is obtained at an energy density of 35 J litre-1 (air flow rate: 60 m3 h-1 residence time: 50 ms TCE inlet concentration: 120 ppm temperature: 298 K). The addition of TCE

R. Vertriest; R. Morent; J. Dewulf; C. Leys; H. Van Langenhove

2003-01-01

405

Variation of Lap Shear Tensile Strength of Polycarbonate–Mild Steel Adhesive Joints with DC Glow Discharge Modified Polycarbonate  

Microsoft Academic Search

It has been observed that the wettability\\/surface energy of polycarbonate (PC) changes with the variation in process parameters,\\u000a such as discharge power and time of exposure of DC glow discharge. The wettability of the PC surface has been measured by\\u000a the contact angle measurements of two test liquids, such as water and formamide, by the sessile drop method. The lap

Amrish K. Panwar; S. K. Barthwal; S. Ray

2007-01-01

406

Application of the glow discharge mass spectrometry (GDMS) for the multi-element trace and ultratrace analysis of sputtering targets  

Microsoft Academic Search

Glow discharge mass spectrometry using a VG9000 high resolution mass spectrometer has been applied to both the multi-element trace and ultra trace analyses of sputtering target materials, i.e. aluminium-based alloys, cobalt-based alloys, titanium and platinum. Element dependent relative sensitivity factors (RSF) have been determined using reference materials in order to provide the possibility for quantitative analyses. Aluminium-based and cobalt-based alloys

C. Venzago; M. Weigert

1994-01-01

407

Quantitative depth profile analysis of boron implanted silicon by pulsed radiofrequency glow discharge time-of-flight mass spectrometry  

Microsoft Academic Search

The analytical potential of pulsed radiofrequency glow discharge time-of-flight mass spectrometry (pulsed-rf-GD-TOFMS) is investigated for fast quantitative analysis of major and dopant elements in bulk and thin film layers. This technique does not require sampling at ultra-high vacuum conditions and so it facilitates high sample throughput compared to reference techniques as secondary ionization mass spectrometry (SIMS). In this paper, bulk

J. Pisonero; L. Lobo; N. Bordel; A. Tempez; A. Bensaoula; N. Badi; A. Sanz-Medel

2010-01-01

408

Radiative lifetime and collisional quenching of carbon monochloride (A ². delta. ) in an alternating current glow discharge  

Microsoft Academic Search

Glow discharges are widely employed in semiconductor processing but are relatively poorly understood owing to, in part, a lack of reliable, quantitative diagnostics. Laser-induced fluorescence promises to be a useful in situ, nonintrusive probe for species concentrations and gas-phase temperatures, but requires the determination of fluoresence yields (i.e., radiative vs nonradiative decay rates) as a function of the plasma state

R. A. Gottscho; R. H. Burton; G. P. Davis

1982-01-01

409

A spectroscopic ellipsometry study of the growth and microstructure of glow-discharge amorphous and microcrystalline silicon films  

Microsoft Academic Search

Spectroscopic ellipsometry (SE) has been used to study the surface, microstructure, and optical properties of glow-discharge deposited amorphous and microcrystalline silicon films. The SE data has been analyzed using multilayer models, effective medium approximation, and linear regression analysis. The studies have shown that with increasing rf power and silane dilution, a gradual transition from good (dense) a-Si:H to a spongy

Satyendra Kumar; D. K. Pandya; K. L. Chopra

1988-01-01

410

Numerical simulation of an oxygen-fed wire-to-cylinder negative corona discharge in the glow regime  

Microsoft Academic Search

Negative glow corona discharge in flowing oxygen has been numerically simulated for a wire-to-cylinder electrode geometry. The corona discharge is modelled using a fluid approximation. The radial and axial distributions of charged and neutral species are obtained by solving the corresponding continuity equations, which include the relevant plasma-chemical kinetics. Continuity equations are coupled with Poisson's equation and the energy conservation

K. Yanallah; F. Pontiga; A. Castellanos

2011-01-01

411

Clostridium beijerinckii mutant obtained by atmospheric pressure glow discharge producing high proportions of butanol and solvent yields.  

PubMed

With 30 g glucose/l as carbon source, Clostridium beijerinckii ART124, a mutant created by atmospheric pressure glow discharge, produced 13.7 g total solvent/l (containing 3.1 g acetone/l, 10.4 g butanol/l and 0.2 g ethanol/l) in 72 h. The mutant could also use sucrose or xylose or a mixture of glucose/xylose/arabinose with nearly equal yields. PMID:21833546

Guo, Ting; Tang, Yan; Xi, Yong-lan; He, Ai-yong; Sun, Bai-jun; Wu, Hao; Liang, Da-feng; Jiang, Min; Ouyang, Ping-kai

2011-07-16

412

4Chlorophenol Degradation and Hydrogen Peroxide Formation Induced by DC Diaphragm Glow Discharge in an Aqueous Solution  

Microsoft Academic Search

In the present study, formation of hydrogen peroxide (H2O2) and degradation of 4-chlorophenol (4-CP) induced by DC diaphragm glow discharge (DGD) in a sodium sulfate solution were\\u000a investigated. The discharge was generated in a small hole on a quarts plate interposed between two submersed graphite electrodes.\\u000a Experimental results showed that 750 V was the optimum voltage for H2O2 formation and 4-CP

Lei Wang

2009-01-01

413

Inhibition of bacterial adhesion on PVC endotracheal tubes by RF-oxygen glow discharge, sodium hydroxide and silver nitrate treatments  

Microsoft Academic Search

Medical-grade poly(vinyl chloride) (PVC) was chemically modified to study how the incorporation of monovalent silver influences Pseudomonas aeruginosa adhesion and colonization. The modification investigated consisted of a radio frequency-oxygen (RF-O2) glow discharge pre-functionalization, followed by a two-step wet-treatment in sodium hydroxide and silver nitrate solutions. X-ray photoelectron spectroscopy (XPS) analysis and contact angle measurements were used to investigate the chemical

D. J. Balazs; K. Triandafillu; P. Wood; Y. Chevolot; C. van Delden; H. Harms; C. Hollenstein; H. J. Mathieu

2004-01-01

414

Comparison in the analytical performance between krypton and argon glow discharge plasmas as the excitation source for atomic emission spectrometry  

Microsoft Academic Search

The emission characteristics of ionic lines of nickel, cobalt, and vanadium were investigated when argon or krypton was employed\\u000a as the plasma gas in glow discharge optical emission spectrometry. A dc Grimm-style lamp was employed as the excitation source.\\u000a Detection limits of the ionic lines in each iron-matrix alloy sample were compared between the krypton and the argon plasmas.\\u000a Particular

Kazuaki Wagatsuma

2009-01-01

415

Surface modification of biomaterials using He glow-discharge plasma and NH3 treatment for augmenting biocompatibility  

Microsoft Academic Search

Helium glow-discharge plasma followed by exposure to ammonia gas was used to enhance biocompatibility of biomaterials. Biocompatibility of polyurethane film was evaluated using endothelial cell growth and contact angle measurements. Human coronary artery endothelial cell (HCAE) growth was studied on (1) untreated, (2) helium plasma-treated and (3) helium plasma-treated polyurethane films followed by exposure to ammonia gas respectively. The untreated

R. Sharma; S. De; M. K. Mazumder

2005-01-01

416

Fluorine and boron co-doped diamond-like carbon films deposited by pulsed glow discharge plasma immersion ion processing  

Microsoft Academic Search

Fluorine (F) and boron (B) co-doped diamond-like carbon (FB-DLC) films were prepared on different substrates by the plasma immersion ion processing (PIIP) technique. A pulse glow discharge plasma was used for the PIIP deposition and was produced at a pressure of 1.33 Pa from acetylene (C2H2), diborane (B2H6), and hexafluoroethane (C2F6) gas. Films of FB-DLC were deposited with different chemical

Xiao-Ming He; M. Hakovirta; A. M. Peters; B. Taylor; M. Nastasi

2002-01-01

417

Electrothermal vaporization for sample introduction into a gas sampling glow discharge time-of-flight mass spectrometer  

Microsoft Academic Search

An electrothermal vaporizer (ETV) has been coupled with a helium-supported gas sampling glow discharge (GSGD) time-of-flight mass spectrometer (TOFMS) for the analysis of small volumes of aqueous solutions. Both the cation (metal) and anion (halide) could both be measured with this source owing to the high ionization potential of the discharge gas. Inorganic halides were transported more effectively than were

John P Guzowski; Jose A. C Broekaert; Gary M Hieftje

2000-01-01

418

Reactive sputter deposition of alumina films on magnesium alloy by double cathode glow-discharge plasma technique  

Microsoft Academic Search

In order to overcome the problem of the corrosion resistance of AZ31 magnesium alloy, the nanocrystalline Al2O3 film was deposited on AZ31 magnesium alloy by double cathode glow-discharge plasma technique. The microstructure, chemical composition and elemental chemical state of the sputter-deposited nanocrystalline Al2O3 film were analyzed by means of scanning electron microscopy equipped with an energy dispersive spectroscope, X-ray diffraction),

Chenghou Zhou; Jiang Xu; Shuyun Jiang

2010-01-01

419

Study of microcrystalline, silicon-carbon p-layers prepared by photo-CVD and glow discharge  

Microsoft Academic Search

Preparation conditions were established for microcrystalline silicon (uc-Si:H) p-type films deposited by both mercury sensitized photochemical vapor deposition and RF glow discharge. The degree of microcrystallinity in individual films was evaluated in terms of the dark conductivity and optical absorption. Both deposition methods have produced uc-Si: p-layers with conductivities as high as 0.5 S\\/cm, and optical band gaps between 2.0

H. Schade

1989-01-01

420

Silane versus silicon tetrafluoride in the growth of microcrystalline silicon films by standard radio frequency glow discharge  

Microsoft Academic Search

Properties of microcrystalline silicon (?c-Si) films produced by standard radio frequency glow discharge from SiH4 or SiF4 precursors were studied. Spectroscopic ellipsometry (SE), Raman spectroscopy and time resolved microwave conductivity (TRMC) were used for their characterisation. Although modelling of SE spectra shows that ?c-Si films with crystalline fractions up to 100% can be deposited from both types of precursors, we

Y. Djeridane; A. Abramov; P. Roca i Cabarrocas

2007-01-01

421

Diagnostics of dielectric barrier discharges in noble gases: atmospheric pressure glow and pseudoglow discharges and spatio-temporal patterns  

Microsoft Academic Search

We present experimental results of atmospheric pressure glow discharges (APGD) in a dielectric barrier discharge reactor. These are examined in different noble gases and in the N2\\/O2 system (air and pure N2), under varying experimental conditions (frequency f; gap length d; and electric field intensity E). Discharge diagnostics have been carried out using ultrahigh speed imaging, and synchronous dual-detection of

Ion Radu; Ray Bartnikas; Grzegorz Czeremuszkin; Michael R. Wertheimer

2003-01-01

422

Glow discharge excitation and matrix effects in the Zn–Al–Cu system in argon and neon  

Microsoft Academic Search

Matrix effects and other deviations from the standard model of glow discharge optical emission spectroscopy (GD-OES) have been investigated in the Zn–Al–Cu system in a Grimm-type discharge in argon and neon. In ionic spectra of the elements that can be ionized by asymmetric charge transfer with ions of the discharge gas, most observed deviations from the standard model can be

Zdenek Weiss

2007-01-01

423

Oxygen glow discharge experiment to remove deposited layers and to release trapped hydrogen isotopes in HT7 superconducting tokamak  

Microsoft Academic Search

An experiment to remove re-deposited layers and to release hydrogen using a glow discharge in oxygen (O-GDC) has been performed in the HT-7 superconducting tokamak. In the absence of magnetic fields, the O-GDC wall conditioning had produced rapid, controlled co-deposit removal. Average removal rates, 5.2 × 1022 H-atoms\\/h, 5.65 × 1021 D-atoms\\/h and 5.53 × 1022 C-atoms\\/h, respectively, were obtained

J. S. Hu; J. G. Li; X. M. Wang

2006-01-01

424

Influence of negative ions in rf glow discharges in SiH4 at 13.56 MHz  

NASA Astrophysics Data System (ADS)

New experimental evidence of the plasma structure has been presented in the rf glow discharge in SiH4 at 13.56 MHz by spatiotemporal emission spectroscopy. Theoretical estimation by the relaxation continuum model strongly supports the accumulative effect of the negative ion, SiH-n, by the electron attachment in the bulk plasma due to the potential barriers in the positive-ion sheath on the discharge structure.

Makabe, Toshiaki; Tochikubo, Fumiyoshi; Nishimura, Motoho

1990-09-01

425

Variation of Lap Shear Tensile Strength of Polycarbonate Mild Steel Adhesive Joints with DC Glow Discharge Modified Polycarbonate  

NASA Astrophysics Data System (ADS)

It has been observed that the wettability/surface energy of polycarbonate (PC) changes with the variation in process parameters, such as discharge power and time of exposure of DC glow discharge. The wettability of the PC surface has been measured by the contact angle measurements of two test liquids, such as water and formamide, by the sessile drop method. The lap shear tensile strength (LSTS) of PC to the mild steel (MS) adhesive joint has been measured with both the as-received polymer and those exposed under DC glow discharge. An appreciable increase in the LSTS has been attained for samples treated under DC glow discharge at a lower power level and also at a short exposure time at higher power. This increase in LSTS is attributed to increased polar surface energy with increasing power and time of exposure. After a certain level of surface modification of the PC, the strength of the adhesive joint deteriorates, while the total surface energy and its polar component may increase continuously. The subsurface damage taking place particularly at long exposure times and at higher power may lead to deterioration of LSTS in spite of a strong interface between the polymer and the adhesive. In such a case, the joint is observed to fracture not across the interface but through the subsurface. The optimum exposure limits the subsurface damage while creating a strong interface.

Panwar, Amrish K.; Barthwal, S. K.; Ray, S.

2007-01-01

426

Emission spectroscopic study on gas-gas interactions in glow discharge plasmas using several binary gas mixtures.  

PubMed

Emission spectra of constituent gas species from glow discharge plasmas using argon-helium, krypton-helium, argon-krypton, and krypton-argon gas mixtures were analyzed to elucidate collisional energy transfer between these gas species occurring in the plasma. In the argon-helium mixed gas plasma, the enhancement or quenching of particular Ar II lines was observed when helium was added to an argon-matrix glow discharge plasma, meaning that a redistribution in the population among the excited levels could be induced through argon-helium collisions. On the other hand, the krypton-helium plasma showed little change in the emission intensities of Kr II lines when helium was added to a krypton-matrix glow discharge plasma, meaning that energy exchanges between krypton and helium excited species occur inactively. These phenomena are principally because the excitation energy as well as the spin multiplicity between collision partners follow both the energy resonance conditions and the spin conservation rule in collisions of the second kind in the argon-helium system, but not in the krypton-helium system. In the argon-krypton and krypton-argon mixed gas plasmas, significant intensity changes of particular Ar II or Kr II lines could not be found; therefore, there were no dominant channels for energy exchanges between argon and krypton species in the mixed gas plasmas. PMID:20215678

Wagatsuma, Kazuaki

2010-01-01

427

Congenital Abnormalities and Multiple Sclerosis  

PubMed Central

Background There is a strong maternal parent-of-origin effect in determining susceptibility to multiple sclerosis (MS). One hypothesis is that an abnormal intrauterine milieu leading to impaired fetal development could plausibly also result in increased susceptibility to MS. A possible marker for this intrauterine insult is the presence of a non-fatal congenital anomaly. Methods We investigated whether or not congenital anomalies are associated with MS in a population-based cohort. We identified 7063 MS index cases and 2655 spousal controls with congenital anomaly information from the Canadian Collaborative Project on Genetic Susceptibility to MS (CCPGSMS). Results The frequency of congential anomalies were compared between index cases and controls. No significant differences were found. Conclusions Congenital anomalies thus do not appear to be associated with MS. However, we did not have complete data on types and severity of congenital anomalies or on maternal birth history and thus this study should be regarded as preliminary.

2010-01-01

428

Formation Of Chromium Nitride Layers Produced By MOPACVD Processes Under Glow Discharge Conditions  

NASA Astrophysics Data System (ADS)

Because of the ecological aspect the electrochemical process of obtaining chromium coatings should be replaced by other technologies. The production of chromium coating involves as the main component of the bath chromium trioxide CrO3 which is very carcinogenic. Moreover the current efficiency of this process is very low what makes it very uneconomical in order to obtain coatings several ?m thick. That is why the new method of obtaining the chromium and chromium nitride coating are searched. The new hybrid technology combining plasma nitriding and PACVD method with the use of metalorganic compounds could have the big practical aspect. This method can be applied for the details with complicated shapes. The paper presents the microstructure and useful properties like corrosion and wear resistance of chromium nitride layers produced by hybrid process which consists of first depositing of chromium coating by PAMOCVD method form liquid precursor 2-ethylheksanoate chromium (III) and then annealing so obtained coating in nitrogen and hydrogen atmosphere using the glow discharge conditions.

Sobiecki, Jerzy Robert; Wierzcho?, Tadeusz

2011-01-01

429

Electrical double layers at shock fronts in glow discharges and afterglows  

NASA Astrophysics Data System (ADS)

This paper examines the propagation of spark-generated shockwaves (1.0glow discharges and their afterglow. Diagnostic methods were employed and expanded in order to capture the dynamics of the shock front in these weakly-ionized, nonmagnetized, collisional plasmas. We used a microwave hairpin resonator to measure the electron number density, and, for all cases, we measured an increase in the electron number density at the shock front. By comparing the increase in electron number density at the shock front in the active discharge and in the afterglow, we conclude that electrons with a temperature much greater than room temperature can be compressed at the shock front. The ratio of electron number density before and after the shock front can be approximately predicted using the Rankine-Hugoniot relationship. The large gradient in electron density, and hence a large gradient in the flux of charged species, created a region of space-charge separation, i.e., a double layer, at the shock front. The double layer balances the flux of charged particles on both sides of the shock front. The double layer voltage drop was measured in the current-carrying discharge using floating probes and compared with previous models. As well, we measured argon 1s5 metastable-state density and demonstrate that metastable-state neutral species can be compressed across a shock front and approximately predicted using the Rankine-Hugoniot relationship.

Siefert, Nicholas S.

2010-12-01

430

Observations of a structure-forming instability in a dc-glow-discharge dusty plasma  

NASA Astrophysics Data System (ADS)

By adjusting the anode current and axial magnetic strength of a dc-glow-discharge dusty plasma, we have found plasma and dust conditions conducive to dusty plasma structurization, similar to the one discussed theoretically by Morfill and Tsytovich [Plasma Phys. Rep.PPHREM1063-780X10.1134/1.1306997 26, 682 (2000)]. The structurization instability leads to the formation of a pattern where the dust suspension transforms into alternating stationary regions of high and low dust densities. We have measured the dependence of the wavelength of the nonpropagating dust density structures on neutral pressure and plasma density and discussed the results in terms of the dispersion relation obtained by D’Angelo [Phys. PlasmasPHPAEN1070-664X10.1063/1.873042 5, 3155 (1998)] for an ionization and ion-drag instability. The observations are also considered in light of a recent theoretical prediction by Khrapak [Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.102.245004 102, 245004 (2009)] that under certain conditions the effects of the polarization force on dust particles can cause dust acoustic waves to stop propagating, resulting in the formation of aperiodic, stationary dust density structures.

Heinrich, J. R.; Kim, S.-H.; Merlino, R. L.

2011-08-01

431

The breakdown and glow phases during the initiation of discharges for lamps  

SciTech Connect

High intensity discharge (HID) lamps are often initiated by the application of one or more short, high-voltage, breakdown pulses superimposed on a 50 or 60 Hz generator voltage. A successful transition from the breakdown event to steady-state operating conditions in HID lamps requires that the lamp-circuit system be adequate to sustain the plasma created during breakdown until the electrodes are heated to thermionic temperatures. In this article, we use a one-dimensional (in the axial direction) transient discharge model to study the conditions needed to sustain the cold-cathode discharge after a breakdown event has occurred. While the application of our one-dimensional model to real lamps is approximate, we find that the model predictions are consistent with experimental results in HID lamps, a few of which are presented here. The main conclusion from this work is that, after breakdown, the voltage necessary to sustain a glow discharge is dependent on the source impedance, the gas composition, and on the plasma density created by the breakdown event. {copyright} {ital 1997 American Institute of Physics.}

Pitchford, L.C.; Peres, I.; Liland, K.B.; Boeuf, J.P. [Centre de Physique des Plasmas et Applications, Universite Paul Sabatier, 118 route de Narbonne, 31062 Toulouse (France); Gielen, H. [Central Development Laboratories, Philips Lighting, Eindhoven (The Netherlands)

1997-07-01

432

Preparation and Characterization of Ir Coating on WC Ceramic by Double Glow Plasma  

NASA Astrophysics Data System (ADS)

Dense and adherent Ir coating was deposited on porous WC ceramic by double glow plasma (DGP). There were two cathodes in the vacuum deposition chamber. The bias voltage of Ir target and WC substrate were -900 and -350 V, respectively. The Ir coating was characterized using scanning electron microscopy, x-ray diffraction, nanoindentation instrument, and scratch tester to examine the microstructure and the mechanical properties. The results indicated that the deposition rate by DGP was up to 5-6 ?m/h which was faster than that by metal-organic chemical vapor deposition and magnetron sputtering. The Ir coating had a preferential growth orientation of (220) crystal face. The hardness was 800 HV. The elastic modulus was 644 GPa. The excellent mechanical properties were attributed to the preferential growth, the large compressive stress, and the shrinkage of the lattice parameters. The adhesive force was up to 51 N. The strong adhesion was attributed to the mechanical locking and chemical reaction between the Ir coating and the porous WC substrate.

Zhang, Zhongwei; Xu, Zhenghui; Wang, Jinming; Wu, Wangping; Chen, Zhaofeng

2012-10-01

433

High frequency glow discharges at atmospheric pressure with micro-structured electrode arrays  

NASA Astrophysics Data System (ADS)

Micro-structured electrode (MSE) arrays allow the generation of large-area uniform glow discharges over a wide pressure range up to atmospheric pressure. The electrode widths, thicknesses and distances in the micrometre range are realized by means of modern micro-machining and galvanic techniques. The electrode distance, the gap width d, is small enough to generate sufficiently high electric field strengths to ignite gas discharges by applying only moderate radio frequency (RF, 13.56 MHz) voltages (80-390 V in Ne, He, Ar, N2 and air). The non-thermal plasma system is characterized by a special probe measuring the electric parameters. We tested MSE arrays with d = 70, 25 and 15 µm. The MSE driven plasmas show a different behaviour from conventional RF discharge plasmas. Due to the very small electrode gap width we can describe the behaviour of the charged particles in the RF field of our system with the dc Townsend breakdown theory, depending on the pressure range and gas. With decreasing pressure, the gas discharges, especially in Ne and He, are increasingly dominated by field electron emission. With the MSE arrays as plasma sources several applications were developed and successfully tested, e.g. decomposition of waste gases and sterilization of food packaging materials at atmospheric pressure.

Baars-Hibbe, L.; Sichler, P.; Schrader, C.; Lucas, N.; Gericke, K.-H.; Büttgenbach, S.

2005-02-01

434

Glow discharge plasma in water: a green approach to enhancing ability of chitosan for dye removal.  

PubMed

There is a need to explore effective and green approaches to enhancing the ability to use chitosan for contaminant removal for practical implementation of this technology. In the present study, glow discharge plasma (GDP), which has thus far been studied for degradation of contaminants, was used for the first time to pre-treat chitosan for dye removal in aqueous solution. The results show that the GDP treatment changed the morphology and crystallinity of chitosan particles, and the number of -CH(2) and -CH(3) groups in the chitosan samples increased. Various pretreatment parameters, including discharge current and time, played significant roles in the chitosan modification. It is observed that dye uptake in GDP-modified chitosan was faster than adsorption in untreated chitosan. The maximum adsorption by chitosan followed the order of untreated chitosan

Wen, Yuezhong; Shen, Chensi; Ni, Yanyan; Tong, Shaoping; Yu, Feng

2011-11-25

435

Observations of a structure-forming instability in a dc-glow-discharge dusty plasma.  

PubMed

By adjusting the anode current and axial magnetic strength of a dc-glow-discharge dusty plasma, we have found plasma and dust conditions conducive to dusty plasma structurization, similar to the one discussed theoretically by Morfill and Tsytovich [Plasma Phys. Rep. 26, 682 (2000)]. The structurization instability leads to the formation of a pattern where the dust suspension transforms into alternating stationary regions of high and low dust densities. We have measured the dependence of the wavelength of the nonpropagating dust density structures on neutral pressure and plasma density and discussed the results in terms of the dispersion relation obtained by D'Angelo [Phys. Plasmas 5, 3155 (1998)] for an ionization and ion-drag instability. The observations are also considered in light of a recent theoretical prediction by Khrapak et al. [Phys. Rev. Lett. 102, 245004 (2009)] that under certain conditions the effects of the polarization force on dust particles can cause dust acoustic waves to stop propagating, resulting in the formation of aperiodic, stationary dust density structures. PMID:21929116

Heinrich, J R; Kim, S-H; Merlino, R L

2011-08-05

436

An ion source for radiofrequency-pulsed glow discharge time-of-flight mass spectrometry  

NASA Astrophysics Data System (ADS)

A Grimm-type glow discharge (GD) has been designed and constructed as an ion source for pulsed radiofrequency GD spectrometry when coupled to an orthogonal time of flight mass spectrometer. Pulse shapes of argon species and analytes were studied as a function of the discharge conditions using a new in-house ion source (UNIOVI GD) and results have been compared with a previous design (PROTOTYPE GD). Different behavior and shapes of the pulse profiles have been observed for the two sources evaluated, particularly for the plasma gas ionic species detected. In the more analytically relevant region (afterglow), signals for 40Ar+ with this new design were negligible, while maximum intensity was reached earlier in time for 41(ArH)+ than when using the PROTOTYPE GD. Moreover, while maximum 40Ar+ signals measured along the pulse period were similar in both sources, 41(ArH)+ and 80(Ar2)+ signals tend to be noticeable higher using the PROTOTYPE chamber. The UNIOVI GD design was shown to be adequate for sensitive direct analysis of solid samples, offering linear calibration graphs and good crater shapes. Limits of detection (LODs) are in the same order of magnitude for both sources, although the UNIOVI source provides slightly better LODs for those analytes with masses slightly higher than 41(ArH)+.

González Gago, C.; Lobo, L.; Pisonero, J.; Bordel, N.; Pereiro, R.; Sanz-Medel, A.

2012-10-01

437

On the accuracy and reliability of different fluid models of the direct current glow discharge  

NASA Astrophysics Data System (ADS)

We developed and tested 2D ``extended fluid model'' of a dc glow discharge using COMSOL MULTIPHYSICS software and implemented two different approaches. First, assembling the model from COMSOL's general form pde's and, second, using COMSOL's built-in Plasma Module. The discharge models are based on the fluid description of ions and excited neutral species and use drift-diffusion approximation for the particle fluxes. The electron transport as well as the rates of electron-induced plasma-chemical reactions are calculated using the Boltzmann equation for the EEDF and corresponding collision cross-sections. The self-consistent electric field is calculated from the Poisson equation. Basic discharge plasma properties such as current-voltage characteristics and electron and ion spatial density distributions as well as electron temperature and electric field profiles were studied. While the solutions obtained by two different COMSOL models are essentially identical, the discrepancy between COMSOL and CFD-ACE+ model solutions is about several percents and caused by the difference in the models due to undocumented details in the software packages. We also studied spatial distributions of particle fluxes in discharge plasma and identified the existence of vortex component of the discharge current.

Rafatov, I.; Bogdanov, E. A.; Kudryavtsev, A. A.

2012-03-01

438

Ion and radical reactions in the silane glow discharge deposition of a-Si:H films  

SciTech Connect

A mass spectrometric analysis of the positive ions and neutral products in a silane glow discharge has been performed. The active species, created by dissociation, disproportionation, and ion-molecule reactions are mainly SiH/sub 2/, SiH/sub 3/, and H. A calculation of the distribution of the SiH/sup +/ /SUB n/ ions shows that the silane concentration monitors the abundance of SiH/sup +//sub 3/. diffusional transport of radicals toward the discharge-tube walls can explain the observed deposition rates. The study of SiH/sub 4/-SiD/sub 4/ and SiH/sub 4/-D/sub 2/ plasmas emphasizes several reactions which modify the free-radical populations depending on the discharge conditions: disproportionation, termination, recombination, and abstration. Heterogeneous reactions have also been observed: etching of the film by H atoms and direct incorporation of hydrogen in the growing film. A general scheme for the plasma deposition mechanism is proposed.

Turban, G.; Catherine, Y.; Grolleau, B.

1982-03-01

439

[Spectroscopic diagnoses of glow discharge plasma for the carbon nitride growth process].  

PubMed

Plasma diagnostics is performed during dc. glow discharge plasma-enhanced chemical vapor deposition (PECVD) on nitride thin films using optical emission spectra. Several molecular bands such as the second positive series of N2 transitions, the first negative series of N2+ and the CN, NH violet bands are identified. Variations of the emission intensities of N2(337.1 nm), N2+(391.4 nm) and CN(388.3 nm) are investigated as the function of the percentage of H2, discharge current and deposition pressure. The related excitation mechanism of the species emission is discussed. Experimental results show that adding a small amount of H2(about 5%) into the gas source will be beneficial to produce all the active species. Higher discharge current will result in an increase of the active species concentration while there is maximum emission intensity at medium gas pressure at about 4 kPa. The collisions between the species, including metastable nitrogen and hydrogen are related with the concentration variations of the measured species. All the results and discussion provide reference data for optimizing the deposition parameters and controlling the deposition process in the synthesis of carbon nitride thin films. PMID:12940034

Yu, Wei; Wang, Shu-fang; Ren, Guo-bin; Li, Xiao-wei; Zhang, Lian-shui; Fu, Guang-sheng

2002-02-01

440

Modification of surface properties of polypropylene (PP) film using DC glow discharge air plasma  

NASA Astrophysics Data System (ADS)

The industrial use of polypropylene (PP) films is limited because of undesirable properties such as poor adhesion and printability. In the present study, a DC glow discharge plasma has been used to improve the surface properties of PP films and make it useful for technical applications. The change in hydrophilicity of modified PP film surface was investigated by contact angle (CA) and surface energy measurements as a function of exposure time. In addition, plasma-treated PP films have been subjected to an ageing process to determine the durability of the plasma treatment. Changes in morphological and chemical composition of PP films were analyzed by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The improvement in adhesion was studied by measuring T-peel and lap shear strength. The results show that the surface hydrophilicity has been improved due to the increase in the roughness and the introduction of oxygen-containing polar groups. The AFM observation on PP film shows that the roughness of the surface increased due to plasma treatment. Analysis of chemical binding states and surface chemical composition by XPS showed an increase in the formation of polar functional groups and the concentration of oxygen content on the plasma-processed PP film surfaces. T-peel and lap shear test for adhesion strength measurement showed that the adhesion strength of the plasma-modified PP films increased compared with untreated films surface.

Pandiyaraj, K. Navaneetha; Selvarajan, V.; Deshmukh, R. R.; Gao, Changyou

441

Co-deposition of Ir-containing Zr coating by double glow plasma  

NASA Astrophysics Data System (ADS)

Ir-Zr co-deposition coatings with 71 at% Zr were deposited on graphite by double glow plasma at 1073-1123 K. The structure and composition of the coatings were confirmed by FE-SEM, XRD, XPS and EDS. The hardness and the elastic modulus of the coatings were estimated by nanoindentation instrument. The adhesion strength between the coating and the substrate was evaluated by a scratch tester. The results showed that the coating was composed of nanocrystalline grains with a size of 80-90 nm compared with 0.5 ?m for the pure Ir coating. The fine grains of the coatings might be attributed to the additional Zr element. New phases IrZr and ZrC were formed due to the high content of Zr and high deposition temperature. The hardness and elastic modulus of the coatings were about 7.5 GPa and 388 GPa, respectively. The adhesive force between the coating and the substrate was about 10 N.

Cong, Xiangna; Chen, Zhaofeng; Wu, Wangping; Chen, Zhou; Edmond Boafo, Fred

2012-10-01

442

Sterilization of Materials with a One Atmosphere Uniform Glow Discharge Plasma.*  

NASA Astrophysics Data System (ADS)

The relatively recent development of the One Atmosphere Uniform Glow Discharge Plasma sterilization technique at the UTK Plasma Science Laboratory has produced initial results which indicate that the technique may have commercial potential. We have shown that active species in a OAUGDP can be applied to the sterilization of fabrics, films, solid materials, and microbiological culture media. With a OAUGDP, we can eliminate the vacuum system which enforces batch processing and requires a continuous input of electrical power. With a OAUGDP, the exposure time is as little as 15 seconds. Sterilization of microorganisms with a kill ratio of 10E6 or higher, can be achieved with minimal unwanted byproducts and at less expense, compared to such conventional sterilization methods as autoclaving, ethylene oxide, or low pressure plasma treatment. This paper discusses the sterilization mechanisms of this new technique, and compares its advantages and disadvantages with other widely used techniques. ^1 Department of Microbiology, UTK ^2 UTK Textiles and Nonwovens Development Center (TANDEC) Research supported in part by the UTK Textiles and Nonwovens Development Center and UTK Center for Materials Processing.

Ku, Yongmin; Brickman, C.; Tosh, K.; Kelly-Wintenberg, K.; Montie, T. C.; Tsai, P.; Wadsworth, L.; Roth, J. Reece

1996-11-01

443

Junction silicon solar cells made with molecular beam glow discharge bombardment  

SciTech Connect

The fabrication of silicon PN junction solar cells with molecular implanted emitter regions is described. A simple, economical high current (0.5 mA/cm/sup 2/), low voltage (4-6 kV) glow discharge apparatus without any ion mass separation is used for implantation. The discharge beam is characterized with a current-voltage conduction curve, radial profile of target sheet resistance and operating temperature of implant target. Molecular implantation compounds discussed include: boron trifluoride, trimethyl borate, boron trichloride, trimethyl phosphite, arsenic trifluoride, phosphorus trichloride, phosphorus oxychloride and arsenic trichloride. Annealing is accomplished with a Q-switched ruby laser and with a standard diffusion furnace. Solar cell performance parameters (conversion efficiency, quantum efficiency and junction ideality) are compared with cells conventionally implanted at 30 keV with /sup 11/B and /sup 31/P and cells made with a standard open tube phosphorus oxychloride diffusion. Cell substrate thickness was found to limit short circuit current. Total area simulated AM1 power conversion efficiencies of molecular cells without antireflection coatings or backsurface fields are at best 8.2% as compared to 9.0% for conventional implanted or diffused devices. To achieve optimum performance, laser light had to be incorporated in the molecular implant annealing procedure.

Caine, E.J.

1982-01-01

444

Femtosecond Laser Ablation Particle Introduction to a Liquid Sampling-Atmospheric Pressure Glow Discharge Ionization Source  

SciTech Connect

This work describes the use of a compact, liquid sampling – atmospheric pressure glow discharge (LS-APGD) ionization source to ionize metal particles within a laser ablation aerosol. Mass analysis was performed with a Thermo Scientific Exactive Mass Spectrometer which utilizes an orbitrap mass analyzer capable of producing mass resolution exceeding M/?M > 160,000. The LS-APGD source generates a low-power plasma between the surface of an electrolytic solution flowing at several µl min-1 through a fused silica capillary and a counter electrode consisting of a stainless steel capillary employed to deliver the laser ablation particles into the plasma. Sample particles of approximately 100 nm were generated with an Applied Spectra femtosecond laser located remotely and transported through 25 meters of polyurethane tubing by means of argon carrier gas. Samples consisted of an oxygen free copper shard, a disk of solder, and a one-cent U.S. coin. Analyte signal onset was readily detectable relative to the background signal produced by the carrier gas alone. The high mass resolution capability of the orbitrap mass spectrometer was demonstrated on the solder sample with resolution exceeding 90,000 for Pb and 160,000 for Cu. In addition, results from a laser ablation depth-profiling experiment of a one cent coin revealed retention of the relative locations of the ~10 µm copper cladding and zinc rich bulk layers.

Carado, Anthony J.; Quarles, C. Derrick; Duffin, Andrew M.; Barinaga, Charles J.; Russo, Richard; Marcus, R. Kenneth; Eiden, Gregory C.; Koppenaal, David W.

2012-01-16

445

Phenol degradation by a nonpulsed diaphragm glow discharge in an aqueous solution.  

PubMed

In the present study, a nonpulsed direct current diaphragm glow discharge process was developed for the first time for phenol degradation in an aqueous solution. The discharge was generated in a small hole in a dielectric diaphragm interposed between two submersed graphite electrodes. The experimental results revealed that supplied voltage, initial pH, iron salts, and radical scavengers impact the phenol degradation significantly. Enhancing the applied voltage, lowering the solution pH, and adding appropriate amounts of Fe2+ or Fe3+ to the solution were found to be favorable for phenol degradation. Carbonate ions or n-butanol in the solution can decelerate the phenol removal. When the treatment time is increased, the pH value of the solution decreased, leading to an increase in the phenol decomposition. It was revealed by high performance liquid chromatography and ionic chromatography that the main intermediates of phenol decomposition are hydroquinone, pyrocatechol, p-benzoquinone and organic acids. In comparison with the high-voltage corona discharge plasma in distilled water, this process offers simple technology, higher energy efficiency, easier scaleup, and easier applicability to salt-containing wastewater with no electrode erosion and electromagnetic radiation. PMID:16294895

Liu, Yong Jun; Jiang, Xuan Zhen

2005-11-01

446

Electrical double layers at shock fronts in glow discharges and afterglows  

SciTech Connect

This paper examines the propagation of spark-generated shockwaves (1.0glow discharges and their afterglow. Diagnostic methods were employed and expanded in order to capture the dynamics of the shock front in these weakly-ionized, nonmagnetized, collisional plasmas. We used a microwave hairpin resonator to measure the electron number density, and, for all cases, we measured an increase in the electron number density at the shock front. By comparing the increase in electron number density at the shock front in the active discharge and in the afterglow, we conclude that electrons with a temperature much greater than room temperature can be compressed at the shock front. The ratio of electron number density before and after the shock front can be approximately predicted using the Rankine-Hugoniot relationship. The large gradient in electron density, and hence a large gradient in the flux of charged species, created a region of space-charge separation, i.e., a double layer, at the shock front. The double layer balances the flux of charged particles on both sides of the shock front. The double layer voltage drop was measured in the current-carrying discharge using floating probes and compared with previous models. As well, we measured argon 1s{sup 5} metastable-state density and demonstrate that metastable-state neutral species can be compressed across a shock front and approximately predicted using the Rankine-Hugoniot relationship.

Siefert, Nicholas S. [Air Force Research Laboratory, Wright Patterson, Ohio 45433 (United States)

2010-12-15

447

Functionalized luminescent nanocrystals on patterned surfaces obtained by radio frequency glow discharges.  

PubMed

In this work a genuine combination of a bottom-up approach, which is based on synthesis and functionalization of emitting nanocrystals (NCs), with a top-down strategy, which relies on a flexible and versatile cold plasma process, is shown. Luminescent semiconducting colloidal NCs consisting of a CdSe core coated with a ZnS shell (CdSe@ZnS) are directly assembled onto micro-patterned substrates previously functionalized by means of glow discharges performed through physical masks. The NC assembly is driven by electrostatic interactions that led to their successful organization into spatially resolved domains. Two distinct protocols are tested, the former using a plasma deposition process combined with an electrostatic layer-by-layer procedure, the latter based on a two-step plasma deposition/treatment process. The procedures are thoroughly monitored with fluorescence microscopy, atomic force microscopy, x-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy and scanning electron microscopy. The two-step plasma protocol is demonstrated to be more efficient in directing a uniform and specific assembly of luminescent NCs with respect to the hybrid procedure. The presented 'mix and match' approach offers great potential for integrating NCs, with their unique size-dependent properties, into microstructures, providing a universal platform for the fabrication of sensors, biochips, displays and switches. PMID:23507981

Sardella, E; Liuzzi, F; Comparelli, R; Depalo, N; Striccoli, M; Agostiano, A; Favia, P; Curri, M L

2013-03-18

448

Characteristics of line pulsed glow discharge plasma at atmospheric pressure for preparation of amorphous carbon films  

NASA Astrophysics Data System (ADS)

Diamond-like carbon (DLC) films have excellent physical and chemical properties for applications such as high mechanical hardness, low friction, chemical inertness, electrical insulation, optical transparency, and biological compatibility. For preparation of large-area amorphous carbon film, the line glow discharge plasma (LGDP) at atmospheric pressure was produced with a high-voltage, high-repetition bipolar pulse using the three-electrode configuration in our experiment. The DBD source plasma was generated by a high-voltage, high-repetition bipolar pulse with a fast rise time using the parallel-plate geometry with a gap width of 2 mm. Two quartz glasses were placed between two electrodes made of stainless-steel to produce DBD. A mixed gas of He as a carrier gas and CH4 as a precursor was supplied to the discharge region. Applying another pulsed bias voltage to the gap between the parallel plate electrode and the bias electrode (stainless-steel substrate), the LGDP was extracted on the substrate for a film deposition. When the pulsed bias voltage was applied to the substrate at several ?s later, the largest intensity of LGDP was observed at the both polarity of bias voltage. We will show the detail characteristics of the LGDP.

Fukui, K.; Miyamae, M.; Kikuchi, Y.; Matsuo, Y.; Horiguchi, Y.; Nishimura, Y.; Nagata, M.; Yatsuzuka, M.

2011-11-01

449

A low frequency impedance matching circuit for a One Atmosphere Uniform Glow Discharge Plasma (OAUGDP) reactor  

SciTech Connect

The One Atmosphere Uniform Glow Discharge Plasma (OAUGDP) is capable of operating at one atmosphere in air and other gases, and its active species can be used, among other things, to sterilize and decontaminate surfaces. The OAUGDP reactor with plasma on can be modeled as two or three capacitors in parallel with a resistor. The non-ideality of the transformer between the RF power supply and the plasma reactor also has an imaginary part in its impedance. Thus, the whole load of the power supply, seen by its output terminals, is highly reactive. The impedance mismatch resulting from the absence of a matching network can cause a large reflected power from the load which does not contribute to plasma formation, but requires an expensive over-rated power supply. In addition, the reactive current can deposit charge on the surface of the dielectric which does not face the plasma. This will disturb the memory voltage, and may complicate attempts to achieve a uniform (as opposed to filamentary) discharge. In this paper, they will present the design details of a new impedance matching circuit which matches the load at the primary side of the transformer. This arrangement avoids dealing with impedance matching components at high voltage in the secondary-side matching circuit presented in last year's paper. Some new data and improvements of plasma reactor operation will also be presented.

Chen, Z.; Sherman, D.M.; Gadri, R.B.; Karakaya, F.; Roth, J.R.

1999-07-01

450

Dark phase effect in the evolution of the positive column of a glow discharge in nitrogen  

SciTech Connect

The characteristics of the initial stage of the formation of the positive column of a glow discharge in nitrogen at reduced pressures are studied experimentally and numerically. A dip in the plasma emission intensity in the initial stage of the discharge (the so-called 'dark phase') is observed experimentally at the positive polarity of the high-voltage electrode (the cathode is grounded). The dark phase is preceded by an ionization wave (IW). When the anode is grounded, neither an IW nor a dip in the discharge emission intensity are observed. A theoretical model capable of describing the discharge development under the actual experimental conditions is constructed. It is shown that the dark phase effect may be caused by the high electron density (above the steady-state one) produced in the gas during the passage of the IW across the discharge gap. This mechanism of the dark phase formation differs from the mechanism proposed earlier to explain a similar effect in noble gases. Additional experiments carried out with pure argon, helium, and helium with a nitrogen admixture have shown that, in the case of a grounded cathode, gas breakdown is also accompanied by the passage of an IW, whereas in the case of a grounded anode, no IW is observed; however, the dark phase is present in both cases. It is shown using computer simulations that, in nitrogen (in contrast to noble gases), the mechanism resulting in the dark phase effect does not operate in the absence of an IW.

Dyatko, N. A. [Troitsk Institute for Innovation and Fusion Research (Russian Federation); Ionikh, Yu. Z.; Meshchanov, A. V. [St. Petersburg State University (Russian Federation); Napartovich, A. P. [Troitsk Institute for Innovation and Fusion Research (Russian Federation); Shishpanov, A. I. [St. Petersburg State University (Russian Federation)

2011-06-15

451

Investigation into the analytical utility of plasma etching in reactive glow discharge plasmas  

SciTech Connect

Tetrafluoromethane (CF{sub 4}, 1.01{percent} by weight) was added to the argon support gas of a hollow cathode glow discharge to investigate the analytical utility of etch atomization. When a conducting copper cathode was analyzed, the sputtering rate (as measured by weight loss) was reduced by a factor of five compared to operation with pure argon. Copper atomic absorbance and copper atomic emission intensity were also reduced by factors of seven and two, respectively. When a nonconducting sample was analyzed, the stainless steel ring that held the sample acted as an auxiliary cathode, supporting the discharge processes. Radical fluoride species formed in this discharge reacted with the nonconducting substrate (silica) to produce volatile SiF{sub 4} that spontaneously evolved into the gas phase, carrying with it copper and uranium. This approach is analogous to plasma etching, a well-established technique for semiconductor processing. Atomic emission data were obtained with a pure argon discharge and an argon/CF{sub 4} discharge. With the addition of CF{sub 4}, a 30{percent} enhancement was observed for uranium in glass and a 50{percent} enhancement for copper in glass. Scanning electron microscopy (SEM) was used to support the supposition that etching of the silica matrix on the inner surface of the hollow cathode contributed to this enhancement. {copyright} {ital 1999} {ital Society for Applied Spectroscopy}

Barshick, C.M. [Chemical and Analytical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6375 (United States); Zook, A.L. [Department of Chemistry, Franklin and Marshall College, Lancaster, Pennsylvania 17604 (United States)] Steiner, R.E. [Nuclear Materials Technoloy Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] King, F.L. [Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506-6045 (United States)

1999-01-01

452

Transient abnormal septal motion after non-surgical closure of the ductus arteriosus.  

PubMed Central

Abnormal septal motion on M mode echocardiography was seen in eight of 16 patients soon after non-surgical closure of the ductus arteriosus. Ten to twenty-nine months after the procedure the abnormal septal motion had disappeared spontaneously. The cross section of the left ventricular cavity was circular both when septal motion was abnormal and when it was normal. Cross sectional echocardiography showed that there was an exaggerated anterior swinging motion of the heart in systole in patients with abnormal septal motion on the M mode recordings. The left ventricular end diastolic diameter before closure was significantly larger, and its reduction after closure was more pronounced in those with abnormal septal motion than in those without. This suggested that the abnormal septal motion was associated with relief of long standing left ventricular volume overload. It is suggested that acute shrinkage of the heart caused temporary laxity of the pericardium, and consequently more movement of the heart within the thorax. The return of normal septal motion suggests that the pericardium gradually shrank to accommodate the smaller heart. Images Fig 1 Fig 4

Beppu, S; Masuda, Y; Sakakibara, H; Izumi, S; Park, Y D; Nagata, S; Miyatake, K; Nimura, Y

1988-01-01

453

Isotope dilution mass spectrometry for quantitative elemental analysis of powdered samples by radiofrequency pulsed glow discharge time of flight mass spectrometry.  

PubMed

In recent years particular effort is being devoted to the development of pulsed glow discharges (PGDs) for mass spectrometry because this powering operation mode could offer important ionization analytical advantages. However, the capabilities of radiofrequency (RF) PGD coupled to a time of flight mass spectrometry (ToFMS) for accurate isotope ratio measurements have not been demonstrated yet. This work is focused on investigating different time positions along the pulse profile for the accurate measurement of isotope ratios. As a result, a method has been developed for the direct and simultaneous multielement determination of trace elements in powdered geological samples by RF-PGD-ToFMS in combination with isotope dilution mass spectrometry (IDMS) as an absolute measurement method directly traceable to the International System of Units. Optimized operating conditions were 70W of applied radiofrequency power, 250Pa of pressure, 2ms of pulse width and 4ms of pulse period, being argon the plasma gas used. To homogeneously distribute the added isotopically-enriched standards, lithium borate fusion of powdered solid samples was used as sample preparation approach. In this way, Cu, Zn, Ba and Pb were successfully determined by RF-PGD-ToF(IDMS) in two NIST Standard Reference Materials (SRM 2586 and SRM 2780) representing two different matrices of geological interest (soil and rock samples). Cu, Zn, Ba and Pb concentrations determined by RF-PGD-ToF(IDMS) were well in agreement with the certified values at 95% confidence interval and precisions below 12% relative standard deviation were observed for three independent analyses. Elemental concentrations investigated were in the range of 81-5770mg/kg, demonstrating the potential of RF-PGD-ToF(IDMS) for a sensitive, accurate and robust analysis of powdered samples. PMID:24054645

Alvarez-Toral, Aitor; Fernandez, Beatriz; Malherbe, Julien; Claverie, Fanny; Molloy, John L; Pereiro, Rosario; Sanz-Medel, Alfredo

2013-06-22

454

Odontodysplasia, gingival manifestations, and accompanying abnormalities.  

PubMed

Regional odontodysplasia is an uncommon developmental dental disorder that may occasionally be accompanied by other abnormalities. A case is described in which the chief report was of a gingival enlargement arising in a female patient who also had dolichocephaly, thin calvarium, clinodactyly and transverse grooving of her fingernails, and a history of abnormal hair. Previously suggested etiologic factors and cases reported in association with other abnormalities are reviewed. PMID:8850490

Fanibunda, K B; Soames, J V

1996-01-01

455

Abnormal grain growth behavior of an  

Microsoft Academic Search

To obtain a superior high temperature creep strength, the transformation of fine-grained structure to large elongated grains\\u000a by abnormal grain growth is an important process for oxide dispersion strengthened superalloys. The present study investigated\\u000a the abnormal grain growth behavior of TMO-2, an experimental alloy possessing higher creep strength than existing ODS alloys.\\u000a It was found that abnormal grain growth was

K. Mino; Y. G. Nakagawa; A. Ohtomo

1987-01-01

456

Radiologic atlas of pulmonary abnormalities in children  

SciTech Connect

This book is an atlas about thoracic abnormalities in infants and children. The authors include computed tomographic, digital subtraction angiographic, ultrasonographic, and a few magnetic resonance (MR) images. They recognize and discuss how changes in the medical treatment of premature infants and the management of infection and pediatric tumors have altered some of the appearances and considerations in these diseases. Oriented toward all aspects of pulmonary abnormalities, the book starts with radiographic techniques and then discusses the normal chest, the newborn, infections, tumors, and pulmonary vascular diseases. There is comprehensive treatment of mediastinal abnormalities and a discussion of airway abnormalities.

Singleton, E.B.; Wagner, M.L.; Dutton, R.V.

1988-01-01

457

Abnormal Mitochondrial Dynamics and Neurodegenerative Diseases  

PubMed Central

Mitochondrial dysfunction is a prominent feature of various neurodegenerative diseases. A deeper understanding of the remarkably dynamic nature of mitochondria, characterized by a delicate balance of fission and fusion, has helped to fertilize a recent wave of new studies demonstrating abnormal mitochondrial dynamics in neurodegenerative diseases. This review highlights mitochondrial dysfunction and abnormal mitochondrial dynamics in Alzheimer disease, Parkinson disease, amyotrophic lateral sclerosis, and Huntington disease and discusses how these abnormal mitochondrial dynamics may contribute to mitochondrial and neuronal dysfunction. We propose that abnormal mitochondrial dynamics represents a key common pathway that mediates or amplifies mitochondrial dysfunction and neuronal dysfunction during the course of neurodegeneration.

Su, Bo; Wang, Xinglong; Zheng, Ling; Perry, George; Smith, Mark A.; Zhu, Xiongwei

2009-01-01

458

[Renal abnormalities in ankylosing spondylitis].  

PubMed

We will study the epidemiologic, clinical, biological, therapeutic, prognostic characteristics and predictive factors of development of nephropathy in ankylosing spondylitis patients. We retrospectively reviewed the medical record of 32 cases with renal involvement among 212 cases of ankylosing spondylitis followed in our service during the period spread out between 1978 and 2006. The renal involvement occurred in all patients a mean of 12 years after the clinical onset of the rheumatic disease. Thirty-two patients presented one or more signs of renal involvement: microscopic hematuria in 22 patients, proteinuria in 23 patients, nephrotic syndrome in 11 patients and decreased renal function in 24 patients (75%). Secondary renal amyloidosis (13 patients), which corresponds to a prevalence of 6,1% and tubulointerstitial nephropathy (7 patients) were the most common cause of renal involvement in ankylosing spondylitis followed by IgA nephropathy (4 patients). Seventeen patients evolved to the end stage renal disease after an average time of 29.8 ± 46 months. The average follow-up of the patients was 4,4 years. By comparing the 32 patients presenting a SPA and renal disease to 88 with SPA and without nephropathy, we detected the predictive factors of occurred of nephropathy: tobacco, intense inflammatory syndrome, sacroileite stage 3 or 4 and presence of column bamboo. The finding of 75% of the patients presented a renal failure at the time of the diagnosis of renal involvement suggests that evidence of renal abnormality involvement should be actively sought in this disease. PMID:22520483

Samia, Barbouch; Hazgui, Faiçal; Abdelghani, Khaoula Ben; Hamida, Fethi Ben; Goucha, Rym; Hedri, Hafedh; Taarit, Chokri Ben; Maiz, Hedi Ben; Kheder, Adel

2012-04-18

459

List mode multichannel analyzer  

DOEpatents

A digital list mode multichannel analyzer (MCA) built around a programmable FPGA device for onboard data analysis and on-the-fly modification of system detection/operating parameters, and capable of collecting and processing data in very small time bins (<1 millisecond) when used in histogramming mode, or in list mode as a list mode MCA.

Archer, Daniel E. (Livermore, CA); Luke, S. John (Pleasanton, CA); Mauger, G. Joseph (Livermore, CA); Riot, Vincent J. (Berkeley, CA); Knapp, David A. (Livermore, CA)

2007-08-07

460

Hereditary evaluation of multiple developmental abnormalities in the Havanese dog breed.  

PubMed

The Havanese is a toy breed that presents with a wide range of developmental abnormalities. Skeletal defects, particularly osteochondrodysplasia (OCD), are the most frequently observed anomalies. Cataracts, liver shunts, heart murmurs, and missing incisors are also common in this breed. Estimates of heritability and complex segregation analyses were carried out to evaluate modes of transmission for these abnormalities. A moderate heritability was identified and evidence for a single major locus was found. Novel statistical analysis methods were used to identify four traits that co-segregate: cataracts, hepatic abnormalities, OCD, and cardiac abnormalities. A canine-specific microarray was used to identify changes in gene expression in the liver that accompany the aforementioned developmental problems. One hundred and thirteen genes were found to be differentially regulated in the Havanese. PMID:17621585

Starr, Alison N; Famula, Thomas R; Markward, Nathan J; Baldwin, Joanne V; Fowler, Karon D; Klumb, Diane E; Simpson, Nancy L; Murphy, Keith E

2007-07-09

461

Corneal Endothelial Abnormalities After SLT.  

PubMed

PURPOSE:: Whitish spots are sometimes observed in the corneal endothelium after selective laser trabeculoplasty (SLT). To evaluate the corneal endothelium after SLT, corneal specular microscopy was performed. METHODS:: A total of 142 eyes with open angle glaucoma that underwent SLT during the period of 9 months from February 10 to November 10, 2012, had their corneal endothelium examined with specular microscopy before and after SLT. RESULTS:: Dark spots were observed in the corneal endothelium on corneal specular microscopy immediately after SLT. Seventy-one of the 142 eyes had no significant dark spots or increase in dark spots after SLT. Thirty-seven of the 142 eyes showed few dark spots after SLT. Thirty-four of the 142 eyes showed numerous dark spots after SLT on specular microscopy imaging, which resolved by 1 month. The last group had the greatest decrease in the corneal endothelial cell count at 1 month after SLT, but this was not statistically significant in this study (P=0.1). CONCLUSIONS:: The corneal endothelial abnormalities after SLT shown in this study may be transient, and long-term effects are probably negligible in normal corneas or single treatments. However, in corneas with reduced transparency of the endothelium, such as compromised corneas and corneas with pigment deposits on the endothelium, there may be a risk of further corneal endothelial compromise, especially after repeated SLT. Larger and longer term studies with histopathologic evaluation would be useful to evaluate the effect of SLT on normal and subnormal corneal endothelium. Until further studies are done, it would be wise to minimize the number and energy of SLT laser shots. PMID:23632397

Ong, Keith; Ong, Leonard; Ong, Lillian B

2013-04-29

462

A Cytogenetic Study of Abnormal Sexual Development.  

National Technical Information Service (NTIS)

Nineteen patients associated with sexual anomalies were studied for chromosome abnormalities. Five cases (26.3 per cent) were found to be chromosomally abnormal. They were one case of mixed gonadal dysgenesis with an XY/XO mosaicism, two cases of Klinefel...

C. C. Lin K. S. W. Kim P. Y. Wei

1969-01-01

463

Severely Symptomatic Craniovertebral Junction Abnormalities in Children  

Microsoft Academic Search

Objectives: The treatment of symptomatic cranio-vertebral junction (CVJ) instability in children affected by CVJ abnormalities is a challenge. A series of severely symptomatic children has been reviewed to understand the controversial long-term effectiveness of the aggressive management of CVJ abnormalities, in terms of clinical improvement, spinal stability and growth. Methods: Three Down syndrome patients, 1 with mucopolysaccharidosis and 1 with

Carlo Giussani; Franck-Emmanuel Roux; Paolo Guerra; David Pirillo; Marco Grimaldi; Giuseppe Citerio; Erik P. Sganzerla

2009-01-01

464

Retinal Circulatory Abnormalities in Type 1 Diabetes  

Microsoft Academic Search

Purpose. To quantify retinal circulatory abnormalities in patients with type 1 diabetes; to compare blood speed and blood flow in major temporal retinal arteries as well as total retinal arterial cross-section measured in patients to that measured in controls without diabetes; to determine which factors are related to the measured abnormalities within the patient group. Methods. The laser Doppler technique

Gilbert T. Feke; Sheldon M. Buzney; Hironobu Ogasawara; Naoki Fujio; Douglas G. Goger; Norman P. Spack; Kenneth H. GabbayX

465