Sample records for abnormal glow mode

  1. {alpha}, {gamma}, and normal, abnormal glow discharge modes in radio-frequency capacitively coupled discharges at atmospheric pressure

    SciTech Connect

    Moon, Se Youn; Rhee, J.K.; Kim, D.B.; Choe, W. [Department of Physics, Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701 (Korea, Republic of)

    2006-03-15

    Discharge modes, {alpha} and {gamma}, of a radio-frequency helium capacitively coupled discharge at atmospheric pressure were investigated with the discharge gap distance between electrodes varied from 1 to 5 mm. As similarly observed in other experiments, the {alpha} and {gamma} mode and the {alpha}-{gamma} mode transition were observed with large drops in the voltage (310-179 V) and the phase angle between the voltage and current (54 deg. -18 deg. ), and a contraction of the plasma volume (8.5-0.17 cm{sup 3}, at 3 mm gap distance). The discharge voltage where the {alpha}-{gamma} mode transition occurred versus the gap distance showed a similar behavior with the Paschen curve for a gas breakdown. Depending on the gap distance, normal and abnormal glow regimes were observed in the {alpha}mode. At 1 and 2 mm, the {alpha} mode remained in the abnormal glow discharge until the {alpha}-{gamma} mode transition occurred as the discharge current increases. At 3 mm, however, the {alpha} mode was excited as a normal glow discharge with a constant current density (17 mA/cm{sup 2}) but it became an abnormal glow discharge as the current increased. At 4 mm, the {alpha} mode was sustained as a normal glow discharge, then the transition to the {gamma} mode occurred. Using a simple resistor-capacitor circuit model and a {alpha} sheath breakdown model, the discharge modes and the mode transition properties were studied.

  2. Optogalvanic effect and measurement of gas temperature in an abnormal glow discharge

    SciTech Connect

    Obradovic, Bratislav M.; Kuraica, Milorad M. [Faculty of Physics, University of Belgrade, P.O. Box 368, 11001 Belgrade (Serbia)

    2006-09-25

    Axial distribution of the gas temperature in an abnormal glow discharge in argon is simultaneously determined by laser optogalvanic and absorption spectroscopy methods. Temperature distributions obtained by two different methods are in a fair agreement except in the boundary region between the cathode fall and the negative glow. Systematically lower temperature in this region obtained by optogalvanic spectroscopy is a consequence of the nature of optogalvanic effect, which, in some circumstances, cannot be identified with spectral line profile.

  3. Optical and Electrical Characteristics of AC Glow-Discharge Plasma in

    Microsoft Academic Search

    Horacio Martínez Valencia; Farouk Bashir Yousif; Arturo Robledo-Martínez; Fermin Castillo Mejia

    2006-01-01

    This paper considers the optical and electrical characterization of an ac glow-discharge plasma in the abnormal glow mode used for optical emission spectroscopy. The total discharge current and applied voltage are measured using conventional techniques. The electrical characteristics of the planer-cathode glow discharge confirmed that the plasma is operating at an abnormal discharge mode characterized by the increases in the

  4. Array of surface-confined glow discharges in atmospheric pressure helium: Modes and dynamics

    SciTech Connect

    Li, D.; Liu, D. X., E-mail: liudingxin@gmail.com, E-mail: mglin5g@gmail.com [Center for Plasma Biomedicine, State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Shaanxi (China); Nie, Q. Y.; Li, H. P. [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Chen, H. L. [Frank Reidy Center for Bioelectrics, Old Dominion University, Norfolk, Virginia 23508 (United States); Kong, M. G., E-mail: liudingxin@gmail.com, E-mail: mglin5g@gmail.com [Center for Plasma Biomedicine, State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Shaanxi (China); Frank Reidy Center for Bioelectrics, Old Dominion University, Norfolk, Virginia 23508 (United States); Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, Virginia 23529 (United States)

    2014-05-19

    Array of atmospheric pressure surface discharges confined by a two-dimensional hexagon electrode mesh is studied for its discharge modes and temporal evolution so as to a theoretical underpinning to their growing applications in medicine, aerodynamic control, and environmental remediation. Helium plasma surface-confined by one hexagon-shaped rim electrode is shown to evolve from a Townsend mode to a normal and abnormal glow mode, and its evolution develops from the rim electrodes as six individual microdischarges merging in the middle of the hexagon mesh element. Within one hexagon element, microdischarges remain largely static with the mesh electrode being the instantaneous cathode, but move towards the hexagon center when the electrode is the instantaneous anode. On the entire array electrode surface, plasma ignition is found to beat an unspecific hexagon element and then spreads to ignite surrounding hexagon elements. The spreading of microdischarges is in the form of an expanding circle at a speed of about 3?×?10{sup 4} m/s, and their quenching starts in the location of the initial plasma ignition. Plasma modes influence how input electrical power is used to generate and accelerate electrons and as such the reaction chemistry, whereas plasma dynamics are central to understand and control plasma instabilities. The present study provides an important aspect of plasma physics of the atmospheric surface-confined discharge array and a theoretical underpinning to its future technological innovation.

  5. Electrophysical properties of polycrystalline diamond films deposited from an abnormal glow discharge

    NASA Astrophysics Data System (ADS)

    Gaydaychuk, A. V.; Kabyshev, A. V.; Konusov, F. V.; Linnik, S. A.; Remnev, G. E.

    2015-04-01

    Electrophysical properties of polycrystalline diamond films (PDF), deposited from the abnormal glow discharge, were obtained. The energetic and kinetic characteristics of surface dark and photoconductivity of PDF and their temperature, field and spectral dependences were investigated. Dominant carrier transport mechanisms, their type and the energetic spectrum of localized defect states were established. Current-voltage characteristics, photosensitivity and activation energy are determined by conductivity of PDF, which varies from 10-14 to 10-4 S depending on deposition conditions. Vacuum annealing of films up to 600-800 K stabilizes the electrical characteristics. Thermal stability of PDF properties higher than semiconductor films, deposited under nonequilibrium conditions by pulsed laser and ion ablation. PDF films not inferior on properties to films, obtained by alternative CVD methods. Electrical characteristics, mechanism of charge transport of PDF were caused by defects of different nature, the energetic levels of which are continuously distributed on energy in the band gap. Dominant n-type of activation conduction is complemented by hopping mechanism through the localized states distributed near the Fermi level with density 5.6×017–2.1×021 eV-1 cm-3. Trapping and recombination centers are heterogeneously distributed on grain boundaries.

  6. Radio frequency atmospheric pressure glow discharge in {alpha} and {gamma} modes between two coaxial electrodes

    SciTech Connect

    Shang Wanli; Wang Dezhen [State Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); Zhang Yuantao [Department of Electronic and Electrical Engineering, Loughborough University, Leicestershire LE11 3TU (United Kingdom)

    2008-09-15

    The discharge in pure helium and the influence of small nitrogen impurities at atmospheric pressure are investigated based on a one-dimensional self-consistent fluid model controlled by a dielectric barrier between two coaxial electrodes. The simulation of the radiofrequency (rf) discharge is based on the one-dimensional continuity equations for electrons, ions, metastable atoms, and molecules, with the much simpler current conservation law replacing the Poisson equation for electric field. Through a computational study of rf atmospheric glow discharges over a wide range of current density, this paper presents evidence of at least two glow discharge modes, namely the {alpha} mode and the {gamma} mode. The simulation results show the asymmetry of the discharge set exercises great influence on the discharge mechanisms compared to that with parallel-plane electrodes. It is shown that the particle densities are not uniform in the discharge region but increase gradually from the outer to the inner electrode in both modes. The contrasting dynamic behaviors of the two glow modes are studied. Secondary electron emission strongly influences gas ionization in the {gamma} mode yet matters little in the {alpha} mode.

  7. Effect of Mirror Magnetic Field on Abnormal Glow Discharge of Four-Anode Device

    Microsoft Academic Search

    Zhongcai Yuan; Jiaming Shi; Bo Xu; Liu Ma

    2008-01-01

    In the four-anode device, the mirror magnetic field affects the characteristics of charged particles motion, so that the current-voltage relations of glow discharge are changed. Firstly, the discharge device is introduced, and the distribution of mirror magnetic field generated by the loops surrounding the discharge chamber is presented. Both the discharge current-voltage characteristics and the radial distributions of electron density

  8. Axial emission profiles and apparent secondary electron yield in abnormal glow discharges in argon

    Microsoft Academic Search

    D. Maric; K. Kutasi; G. Malovic; Z. Donkó; Z. Lj. Petrovi?

    2002-01-01

    :   This paper reports investigations of argon glow discharges established between flat disk electrodes, at pressure × electrode\\u000a separation values between 45 Pa cm and 150 Pa cm. Parallel to the experimental studies the discharge is also described by\\u000a a self-consistent hybrid model. The model uses as input data the measured electrical characteristics, this way making it possible\\u000a to determine

  9. Irregular-regular-irregular mixed mode oscillations in a glow discharge plasma

    NASA Astrophysics Data System (ADS)

    Ghosh, Sabuj; Shaw, Pankaj Kumar; Saha, Debajyoti; Janaki, M. S.; Iyengar, A. N. Sekar

    2015-05-01

    Floating potential fluctuations of a glow discharge plasma are found to exhibit different kinds of mixed mode oscillations. Power spectrum analysis reveals that with change in the nature of the mixed mode oscillation (MMO), there occurs a transfer of power between the different harmonics and subharmonics. The variation in the chaoticity of different types of mmo was observed with the study of Lyapunov exponents. Estimates of correlation dimension and the Hurst exponent suggest that these MMOs are of low dimensional nature with an anti persistent character. Numerical modeling also reflects the experimentally found transitions between the different MMOs.

  10. Atmospheric Pressure Glow Discharges

    SciTech Connect

    Graham, W. G.; Nersisyan, G. [International Research Centre for Experimental Physics, Queens University Belfast, BT7 1NN, Northern Ireland (United Kingdom)

    2006-12-01

    Their relative engineering simplicity, plasma uniformity and chemistry make Atmospheric Pressure Glow Discharges (APGD) very attractive for plasma processing applications. Here some of the basic characteristics of glow discharges are introduced. The basic dielectric barrier discharge and how it can be operated in a uniform glow rather filamentary mode is described. Electrical and laser-based measurements that throw light on the underlying physics of APGDs are presented, along with a model which seeks to explore the plasma chemistry of these discharges.

  11. Glow Dog Glow

    E-print Network

    Hacker, Randi

    2011-08-17

    Broadcast Transcript: South Korean researchers, ever striving to be top in science, have cloned a glow-in-the-dark dog. The little beagle was engineered by inserting genes from species--like jellyfish--that produce fluorescent proteins. The gene...

  12. A brush-shaped air plasma jet operated in glow discharge mode at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Li, Xuechen; Bao, Wenting; Jia, Pengying; Di, Cong

    2014-07-01

    Using ambient air as working gas, a direct-current plasma jet is developed to generate a brush-shaped plasma plume with fairly large volume. Although a direct-current power supply is used, the discharge shows a pulsed characteristic. Based on the voltage-current curve and fast photography, the brush-shaped plume, like the gliding arc plasma, is in fact a temporal superposition of a moving discharge filament in an arched shape. During it moves away from the nozzle, the discharge evolves from a low-current arc into a normal glow in one discharge cycle. The emission profile is explained qualitatively based on the dynamics of the plasma brush.

  13. Spot Mode Operation of a Low-Pressure Helium–Xenon Glow Discharge

    Microsoft Academic Search

    Jörn Winter; Hartmut Lange

    2011-01-01

    The cathode region (CR) of a low-pressure He-Xe discharge with a flat thermionic emitting cathode in spot mode has been experimentally investigated by means of tunable diode laser absorption spectroscopy. Due to the strong inhomogeneity of the spot plasma, a multidimensional consideration of the CR is necessary to obtain correct results. This was achieved by an experimental setup, which provides

  14. Abnormal lateralization of functional connectivity between language and default mode regions in autism

    PubMed Central

    2014-01-01

    Background Lateralization of brain structure and function occurs in typical development, and abnormal lateralization is present in various neuropsychiatric disorders. Autism is characterized by a lack of left lateralization in structure and function of regions involved in language, such as Broca and Wernicke areas. Methods Using functional connectivity magnetic resonance imaging from a large publicly available sample (n?=?964), we tested whether abnormal functional lateralization in autism exists preferentially in language regions or in a more diffuse pattern across networks of lateralized brain regions. Results The autism group exhibited significantly reduced left lateralization in a few connections involving language regions and regions from the default mode network, but results were not significant throughout left- and right-lateralized networks. There is a trend that suggests the lack of left lateralization in a connection involving Wernicke area and the posterior cingulate cortex associates with more severe autism. Conclusions Abnormal language lateralization in autism may be due to abnormal language development rather than to a deficit in hemispheric specialization of the entire brain. PMID:24502324

  15. Abnormal Default-Mode Network Homogeneity in First-Episode, Drug-Naive Major Depressive Disorder

    PubMed Central

    Guo, Wenbin; Liu, Feng; Zhang, Jian; Zhang, Zhikun; Yu, Liuyu; Liu, Jianrong; Chen, Huafu; Xiao, Changqing

    2014-01-01

    Background Default mode network (DMN) is one of the most commonly recognized resting-state networks in major depressive disorder (MDD). However, the homogeneity of this network in MDD is poorly understood. As such, this study was conducted to determine whether or not an abnormal network homogeneity (NH) of DMN is observed in patients with first-episode and drug-naive MDD. Methods Twenty-four first-episode drug-naive patients with MDD and twenty-four healthy control subjects participated in the study. NH and independent component analysis (ICA) methods were used to analyze data. Results Depressed patients exhibited a significantly increased NH in the left dorsal medial prefrontal cortex (MPFC) and decreased NH in the right inferior temporal gyrus (ITG) compared with the healthy control subjects. Receiver operating characteristic curves (ROC) were analyzed and results revealed that the NH values of MPFC and ITG could be applied as candidate markers with relatively high sensitivity and specificity to distinguish patients from healthy control subjects. No correlation was observed between the NH values of the two regions and clinical variables. Conclusions Our findings suggested that an abnormal DMN homogeneity could be observed in MDD, which highlight the importance of the DMN in the pathophysiology of MDD. PMID:24609111

  16. Thar She Glows!

    NSDL National Science Digital Library

    Oregon Museum of Science and Industry

    1997-01-01

    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.

  17. Phenomena of oscillations in atmospheric pressure direct current glow discharges

    SciTech Connect

    Liu, Fu-cheng [College of Physics Science and Technology, Hebei University, Baoding 071002 (China)] [College of Physics Science and Technology, Hebei University, Baoding 071002 (China); Yan, Wen; Wang, De-zhen [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)] [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)

    2013-12-15

    Self-sustained oscillations in a dc glow discharge with a semiconductor layer at atmospheric pressure were investigated by means of a one-dimensional fluid model. It is found that the dc glow discharge initially becomes unstable in the subnormal glow region and gives rise to oscillations of plasma parameters. A variety of oscillations with one or more frequencies have been observed under different conditions. The discharge oscillates between the glow discharge mode and the Townsend discharge mode in the oscillations with large amplitude while operates in the subnormal glow discharge mode all the while in the oscillations with small amplitude. Fourier Transform spectra of oscillations reveal the transition mechanism between different oscillations. The effects of semiconductor conductivity on the oscillation frequency of the dominant mode, gas voltage, as well as the discharge current have also been analyzed.

  18. Glow in the Dark

    NSDL National Science Digital Library

    2012-12-27

    Learners experiment to see which colors of light will cause a phosphorescent (glow-in-the-dark) material to glow. Different colors of light have different wavelengths, and different amounts of energy. Only the colors which shine with sufficient energy can charge up the phosphorescent material enough to glow in the dark. This activity starts on p.26 of the manual. This manual contains four activities related to the Spectra: The Original Laser Superhero Force comic book published by the American Physical Society.

  19. Glowing in the Dark

    NSDL National Science Digital Library

    Science Friday

    2011-01-01

    In this activity, learners explore phosphorescence and how certain materials can absorb and store energy from a light source. Learners use critical thinking skills to hypothesize which type of light -- incandescent, ultraviolet, infrared or fluorescent -- will produce the brightest glow from a glow-in-the-dark star. Learners perform an experiment using cameras to observe the intensity of the resulting glow from each type of light source.

  20. Glow discharge detector

    DOEpatents

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

    2002-01-01

    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.

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

    Microsoft Academic Search

    E. A. Den Hartog; D. A. Doughty; J. E. Lawler

    1988-01-01

    Various laser diagnostics are used to study the cathode fall and negative-glow regions of a helium glow discharge with a cold aluminum 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

  2. Axial structure of dc glow discharge negative glow in nitrogen

    NASA Astrophysics Data System (ADS)

    Lisovskiy, Valeriy; Koval, Veronika; Kravchenko, Ekaterina; Yegorenkov, Vladimir

    2012-10-01

    This paper reports the studies with a Langmuir probe technique of axial plasma parameters such as electron temperature, potential, electric field and plasma concentration of dc glow discharge negative glow in nitrogen at different gas pressure values. Electron temperature in the negative glow decreases from the cathode sheath boundary and it approaches the smallest value at the anode end of the negative glow. Along the negative glow the plasma potential lowers by about 5 V. Axial profile of plasma concentration possesses a maximum in the negative glow near the cathode sheath boundary similar to the case of low pressure. Along the negative glow the plasma concentration decreases by about 16 times and it approaches its minimum in the transition region to the Faraday dark space. Note that the plasma concentration decrease by 15-16 times was observed at all nitrogen pressure and discharge current values when the negative glow completely found its place within the inter-electrode gap.

  3. Numerical Study on Glow Discharge of IEC Fusion

    SciTech Connect

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

    2005-05-15

    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'.

  4. Stable glow discharge detector

    DOEpatents

    Koo, Jackson C.; Yu, Conrad M.

    2004-05-18

    A highly sensitive electronic ion cell for the measurement of trace elements in He carrier gas which involves glow discharge. A constant wave (CW) stable 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 stable glow discharge detector utilizes a floating pseudo-electrode to form a probe in or near the plasma and a solid rod electrode. By using this probe, the large variation of electron density due to trace amounts of impurities can be directly measured. The solid rod electrode provides greater stability and thus easier alignment.

  5. 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!

  6. Effect of cathode surface area and separately stabilized cathodes on high power glow discharges for CO2 laser excitation

    Microsoft Academic Search

    D. R. Evans; J. E. Harry

    1988-01-01

    Results are presented which indicate the importance of the cathode surface area and the advantage of using separately stabilized cathodes for the excitation of high power CO2 lasers. The results indicate that operation of a glow discharge with multiple cathodes of adequate surface area enables operation in the abnormal glow region at higher currents than with a single cathode of

  7. Effect of cathode surface area and separately stabilized cathodes on high power glow discharges for CO2 laser excitation

    Microsoft Academic Search

    D. R. Evans; J. E. Harry

    1988-01-01

    Results are presented which indicate the importance of the cathode surface area and the advantage of using separately stabilized cathodes for the excitation of high power COâ lasers. The results indicate that operation of a glow discharge with multiple cathodes of adequate surface area enables operation in the abnormal glow region at higher currents than with a single cathode of

  8. Transition of Discharge Mode of a Local Hollow Cathode Discharge

    NASA Astrophysics Data System (ADS)

    Li, Shang; Ouyang, Ji-Ting; He, Feng

    2010-06-01

    The discharge characteristics of hollow cathode discharge in argon in a cylindrical cavity are investigated experimentally. The voltage-current (V - I) characteristics and the light emission are measured. It is found that the discharge plasma is localized inside the hollow cavity, with an extensive Faraday dark space between the cathode and the anode. The discharge develops from predischarge to abnormal glow discharge, the hollow cathode effect (HCE) and a hybrid mode as the discharge current increases. The onset of the HCE is found for the first time by the transition from abnormal glow discharge together with a significant decrease in the slope of the V - I curve which shows a positive differential resistivity. The voltage increases proportionally with the current when the HCE is reached.

  9. Hydrogen lines in auroral glow

    Microsoft Academic Search

    A. Omholt; W. Stoffregen; H. Derblom

    1962-01-01

    The paper reports some observations of aurora over northern Scandinavia with a new photoelectric spectrograph. The aurorae consisted of a weak but persistent glow showing an unusual strong H[alpha] line, and of distinct, brighter forms showing no trace of H[alpha]. Between the brighter forms and the glow a dark area occurred. The observations are discussed briefly and it is found

  10. Detection of surface glow related to spacecraft glow phenomenon

    SciTech Connect

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

    1986-02-01

    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.

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

    SciTech Connect

    Ha Yan [College of Mathematics and Computer Science, Hebei University, Baoding 071002 (China); Wang Huijuan [School of Mathematics and Physics, North China Electric Power University, Baoding 071003 (China); Wang Xiaofei [College of Physics Science and Technology, Hebei University, Baoding 071002 (China)

    2012-01-15

    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.

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

    SciTech Connect

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

    1988-09-01

    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.

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

    SciTech Connect

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

    1988-09-01

    Various laser diagnostics are used to study the cathode fall and negative-glow regions of a helium glow discharge with a cold aluminum 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 of 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.

  14. Sound wave propagation through glow discharge plasma

    Microsoft Academic Search

    Vadim P. Stepaniuk

    2005-01-01

    This work investigates the use of glow discharge plasma for acoustic wave manipulation. The broader goal is the suppression of aerodynamic noise using atmospheric glow discharge plasma as a sound barrier. Part of the effort was devoted to the development of a system for the generation of a large volume stable DC glow discharge in air both at atmospheric and

  15. 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...

  16. Congenital Abnormalities

    MedlinePLUS

    ... and may develop serious health problems (e.g. Down syndrome ). Single-Gene Abnormalities Sometimes the chromosomes are normal ... Detecting Genetic Abnormalities Prenatal Genetic Counseling Children with Down Syndrome: Health Care Information for Families Last Updated 5/ ...

  17. Glow discharge initiation with electron gun assist

    SciTech Connect

    Holtrop, K.L.; Jackson, G.L.; Schaubel, K.M.; Kellman, A.G.

    1991-11-01

    Helium glow discharge conditioning is used before every discharge in the D3-D Tokamak to desorb hydrogen and low Z impurities from the graphite and Inconel plasma facing surfaces. However high gas pressure is required to initiate each glow discharge session and this requires frequent cycling of valves to protect pressure sensitive devices. To alleviate this mechanical fatigue an electron gun assisted glow system (EAG) is being installed on the D3-D vessel to lower the initiation pressure. Through the injection of electrons the initiation pressure of the helium glow discharge has been lowered by a factor of 70, bringing the initiation pressure within a factor of 2 of the minimum sustaining pressure of the glow discharge. This might also make possible pulsed glow conditioning which would allow a lower average pressure during glow conditioning reducing the heat load on proposed cryogenic pumping panels. Experimental results of the electron assist on He glow initiation and a scaling model for the electron gun assisted glow will be presented. The electron gun can also be used as a diagnostic. Without a glow discharge, the electron gun has been pulsed into the wall and desorbed gas measured by a Residual Gas Analyzer. We are attempting to correlate the desorbed gas with recycling or vessel cleanliness.

  18. Negative glow discharges for lighting

    SciTech Connect

    Kudryavtsev, A.A.; Lasaryuk, S.N. [Saint-Petersburg Univ. (Russian Federation); Sheverev, V.A. [Polytechnic Univ., Brooklyn, NY (United States)

    1996-12-31

    Results of experimental and theoretical studies of negative glow (NG) discharge devices with original electrode configurations are reported. For the conventional low pressure discharge, the radiation intensity of the negative glow is several times greater than that of the positive column because most of the energy supplied to the NG is converted to excitation and ionization of gas particles. However, applications of NG plasmas have been impaired by the practical difficulty of obtaining extended NG. For laser-pumping, extended negative glow plasmas has been achieved with electrode constructions called hollow cathodes (HC). They can be described as discharge devices in which the cathode surrounds a volume of space, forming a cavity. The anode is placed so that the minimal distance between the cathode and the anode, d, conforms to the condition of hindered discharge. Extended NG plasmas are formed in the space surrounded by the cathode, and no positive column develops. In contrast to various kinds of HC, electrode configurations where an extended NG plasma is formed outside the electrodes are presented. A self-sustained kinetic model of the discharges is developed. Predicted electrical and spectroscopic characteristics of the discharge plasmas are compared with experimental measurements.

  19. Nail abnormalities

    MedlinePLUS

    Beau's lines; Fingernail abnormalities; Spoon nails; Onycholysis; Leukonychia; Koilonychia; Brittle nails ... of the nail bed from the nail plate (onycholysis). Severe illness or surgery may cause horizontal depressions ...

  20. Optical emission analysis of solid samples by decoupled sputtering\\/excitation using a low fluence laser synchronized with a pulsed glow discharge

    Microsoft Academic Search

    K. A. Tereszchuk; J. M. Vadillo; J. J. Laserna

    2009-01-01

    The use of a microsecond-pulsed glow discharge, synchronized with an ablation laser operating under breakdown fluence, assists in the excitation of the ablated material generated during the analysis. With the glow discharge operating in pulsed mode, it is possible to synchronize accurately both sources to maximize the signal. Additionally, both sources can be independently adjusted to optimize the sample removal

  1. Gas flow effects on the submicrosecond pulsed atmospheric pressure glow discharges

    SciTech Connect

    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

    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.

  2. Glow Fast, Glow Slow: Alter the Rate of a Reaction!

    NSDL National Science Digital Library

    Oregon Museum of Science and Industry

    1997-01-01

    Learners investigate one factor affecting reaction rates: temperature. In a darkened room, two identical lightsticks are placed in water -- one in hot water and one in cold water. The lightstick in the hot water glows brighter than the lightstick in the cold water since the light-producing reaction is faster in hot water. This activity, located on page 2 of the PDF, is one of three activities in the Take Home guide for the Chemical Reactions unit in OMSI's Chemistry Lab. Also included on the PDF are two additional activities: Cloudy Globs and Gas Production.

  3. Glow Sticks: Spectra and Color Mixing

    ERIC Educational Resources Information Center

    Birriel, Jennifer; Birriel, Ignacio

    2014-01-01

    Glow sticks are a popular Halloween staple familiar to most of our students. The production of light via a chemical reaction is called "chemiluminescence," and glow sticks are often used as demonstrations and experiments in the chemistry classroom to study reaction rates as a function of temperature. A black light can be used to…

  4. Glow discharge in a gas flow

    Microsoft Academic Search

    E. P. Velikhov; V. S. Golubev; S. V. Pashkin

    1982-01-01

    The status of research on glow discharges in a gas flow, used in pumping fast-flow lasers, is reviewed. Systematic study of this discharge began about 10 years ago. This discharge form, according to a number of properties (current flow mechanism, nature of the development of instabilities, etc.), differs considerably from the well-studied glow discharge in tubes. One of the distinguishing

  5. APEX reveals glowing stellar nurseries

    NASA Astrophysics Data System (ADS)

    2008-11-01

    Illustrating the power of submillimetre-wavelength astronomy, an APEX image reveals how an expanding bubble of ionised gas about ten light-years across is causing the surrounding material to collapse into dense clumps that are the birthplaces of new stars. Submillimetre light is the key to revealing some of the coldest material in the Universe, such as these cold, dense clouds. Glowing Stellar Nurseries ESO PR Photo 40/08 Glowing Stellar Nurseries The region, called RCW120, is about 4200 light years from Earth, towards the constellation of Scorpius. A hot, massive star in its centre is emitting huge amounts of ultraviolet radiation, which ionises the surrounding gas, stripping the electrons from hydrogen atoms and producing the characteristic red glow of so-called H-alpha emission. As this ionised region expands into space, the associated shock wave sweeps up a layer of the surrounding cold interstellar gas and cosmic dust. This layer becomes unstable and collapses under its own gravity into dense clumps, forming cold, dense clouds of hydrogen where new stars are born. However, as the clouds are still very cold, with temperatures of around -250? Celsius, their faint heat glow can only be seen at submillimetre wavelengths. Submillimetre light is therefore vital in studying the earliest stages of the birth and life of stars. The submillimetre-wavelength data were taken with the LABOCA camera on the 12-m Atacama Pathfinder Experiment (APEX) telescope, located on the 5000 m high plateau of Chajnantor in the Chilean Atacama desert. Thanks to LABOCA's high sensitivity, astronomers were able to detect clumps of cold gas four times fainter than previously possible. Since the brightness of the clumps is a measure of their mass, this also means that astronomers can now study the formation of less massive stars than they could before. The plateau of Chajnantor is also where ESO, together with international partners, is building a next generation submillimetre telescope, ALMA, the Atacama Large Millimeter/submillimeter Array. ALMA will use over sixty 12-m antennas, linked together over distances of more than 16 km, to form a single, giant telescope. APEX is a collaboration between the Max-Planck-Institute for Radio Astronomy (MPIfR), the Onsala Space Observatory (OSO) and ESO. The telescope is based on a prototype antenna constructed for the ALMA project. Operation of APEX at Chajnantor is entrusted to ESO.

  6. Laser tube utilizing negative glow

    SciTech Connect

    Fujii, K.; Otaka, M.

    1985-04-09

    A laser tube including an anode and a hollow cathode and adapted to obtain laser oscillation by utilizing a negative glow generated in a space within the hollow cathode. The laser tube has an elongate cylindrical member in which the anode and the hollow cathode are disposed opposite to each other, and the hollow cathode has formed therein a plurality of holes for communication between its internal space and the space outside thereof. The laser tube may further include a conducting grid provided in proximity to the anode and a conducting grid provided in a cathode dark space.

  7. Atmospheric sampling glow discharge ionization source

    DOEpatents

    McLuckey, Scott A. (Oak Ridge, TN); Glish, Gary L. (Oak Ridge, TN)

    1989-01-01

    An atmospheric sampling glow discharge ionization source that can be used in combination with an analytical instrument which operates at high vacuum, such as a mass spectrometer. The atmospheric sampling glow discharge ionization source comprises a chamber with at least one pair of electrodes disposed therein, an inlet for a gaseous sample to be analyzed and an outlet communicating with an analyzer which operates at subatmospheric pressure. The ionization chamber is maintained at a pressure below atmospheric pressure, and a voltage difference is applied across the electrodes to induce a glow discharge between the electrodes, so that molecules passing through the inlet are ionized by the glow discharge and directed into the analyzer. The ionization source accepts the sample under atmospheric pressure conditions and processes it directly into the high vacuum instrument, bridging the pressure gap and drawing off unwanted atmospheric gases. The invention also includes a method for analyzing a gaseous sample using the glow discharge ionization source described above.

  8. Spectroscopic characterisation of an atmospheric pressure glow discharge (APGD)

    NASA Astrophysics Data System (ADS)

    Gomez, S.; Steen, P. G.; Morrow, T.; Graham, W. G.; Herbert, P. A. F.

    2000-10-01

    Recently there has been considerable interest in atmospheric discharges operating in a glow discharge mode i.e. with a spatial and sheath structure similar to that of low pressure glow discharges [1,2,3]. Here spectroscopy has been used to characterise an atmospheric pressure glow discharge (APGD), operating in air but with various other gases flowing through the inter-electrode space and with textile samples ranging from polyester to wool also present in that space. The emission spectra from 250nm to 800nm were dominated by emission from N2 but when textile samples were present OH emission at around 310nm was also observed. Electron temperatures of 0.5 ± 0.1 eV were determined from the relative intensities of Ar emission lines. When nitrogen was the flowing gas the vibrational states exhibited a Maxwellian distribution with a temperature of 2000K. 1. S. Kanazana et al. J.Phys.D., 21, 836 (1988) 2. J.R.Roth, Industrial Plasma Engineering. (IOPP, London ) 1995 3. F. Massine et al. J. Appl. Phys. 83, 3411-3420 (1998)

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

    PubMed

    Park, Yeong-Shin; Hwang, Y S

    2010-02-01

    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(2) at low discharge power of 175 W where ion density of plasma ball is estimated to be over 3.7x10(12) cm(-3). PMID:20192432

  10. Enhancement in ion beam current with layered-glows in a constricted dc plasma ion sourcea)

    NASA Astrophysics Data System (ADS)

    Park, Yeong-Shin; Hwang, Y. S.

    2010-02-01

    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/cm2 at low discharge power of 175 W where ion density of plasma ball is estimated to be over 3.7×1012 cm-3.

  11. Electrical characteristics of arc-free high-power pulsed sputtering glow plasma

    Microsoft Academic Search

    K. Yukimura; R. Mieda; H. Tamagaki; T. Okimoto

    2008-01-01

    A high power pulsed sputtering (HPPS) plasma is generated using a Penning discharge, and is featured to be highly ionized in a glow discharge mode. An electric field and a magnetic field are parallel to each other. Argon ions are initially produced in the plasma and are accelerated towards the cathode as a sputtering target. An arc-free plasma can be

  12. Chromosomal abnormalities

    SciTech Connect

    Goh, K.; Jacox, R.F.; Anderson, F.W.

    1980-09-01

    Cytogenetic studies from the peripheral blood of a patient with malignant lymphoma and rhematoid arthritis who was treated with intra-articular gold Au 198 revealed mosaicism with a normal female metaphase and a 43-chromosome metaphase. The abnormal cell line showed six missing normal chromosomes and three morphologically abnormal chromosomes. The trypsin-digested G-banding metaphases showed that the marker chromosomes were an isochromosome of the long arm of chromosome 17, a translocated chromosome that involved the long arm of chromosome 4 and a chromosome 16, and a translocated chromosome that involved the long arm of chromosome 4 and a chromosome 5. It is tempting to conclude that these abnormalities were due to the gold Au 198 treatment, but we cannot exclude other possibilities.

  13. Glow discharge plasma deposition of thin films

    DOEpatents

    Weakliem, Herbert A. (Pennington, NJ); Vossen, Jr., John L. (Bridgewater, NJ)

    1984-05-29

    A glow discharge plasma reactor for deposition of thin films from a reactive RF glow discharge is provided with a screen positioned between the walls of the chamber and the cathode to confine the glow discharge region to within the region defined by the screen and the cathode. A substrate for receiving deposition material from a reactive gas is positioned outside the screened region. The screen is electrically connected to the system ground to thereby serve as the anode of the system. The energy of the reactive gas species is reduced as they diffuse through the screen to the substrate. Reactive gas is conducted directly into the glow discharge region through a centrally positioned distribution head to reduce contamination effects otherwise caused by secondary reaction products and impurities deposited on the reactor walls.

  14. Probiotic Bacteria Induce a ‘Glow of Health’

    E-print Network

    Levkovich, Tatiana

    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 ...

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

    SciTech Connect

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

    2010-01-25

    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.

  16. Magnetic stabilization of a rotating glow discharge

    Microsoft Academic Search

    J. E. Harry; D. R. Evans

    1987-01-01

    A series of measurements have been made on a magnetically rotated glow discharge over a range of pressure of 24–53 mbars. An increase in the current at which the glow-to-arc transition occurred from 550 mA for a stationary discharge to 2.5 A at a magnetic flux density of 0.025 T for a rotating discharge, with a corresponding power increase at

  17. Analysis of cold cathode glow neon discharges without anode glow or positive column †

    Microsoft Academic Search

    H. M. GRIMLEY; K. G. EMELEUS

    1971-01-01

    Plasma data given previously for the negative glow and Faraday dark space of near-normal cold cathode discharges in neon are supplemented by results, described briefly, for similar discharges without positive column or anode glow. The axial plasma electron concentration curves, which are sharply peaked near the cathode dark space when the cathode rays are strongly attenuated towards the anode, flatten

  18. Io Glowing in the Dark

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Volcanic hot spots and auroral emissions glow on the darkside of Jupiter's moon Io in the image at left. The image was taken by the camera onboard NASA's Galileo spacecraft on 29 June, 1996 UT while Io was in Jupiter's shadow. It is the best and highest-resolution image ever acquired of hot spots or auroral features on Io. The mosaic at right of 1979 Voyager images is shown with an identical scale and projection to identify the locations of the hot spots seen in the Galileo image. The grid marks are at 30 degree intervals of latitude and longitude. North is to the top.

    In the nighttime Galileo image, small red ovals and perhaps some small green areas are from volcanic hot spots with temperatures of more than about 700 kelvin (about 1000 degrees Fahrenheit). Greenish areas seen near the limb, or edge of the moon, are probably the result of auroral or airglow emissions of neutral oxygen or sulfur atoms in volcanic plumes and in Io's patchy atmosphere. The image was taken from a range of 1,035,000 kilometers (about 643,000 miles).

    The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

    This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo

  19. Saddle-field glow-discharge deposition of amorphous semiconductors

    SciTech Connect

    Gaspari, F.; Sidhu, L.S.; O`Leary, S.K.; Zukotynski, S. [Univ. of Toronto, Ontario (Canada). Dept. of Electrical and Computer Engineering

    1996-12-31

    The authors present a dc saddle-field glow-discharge deposition procedure which combines the positive attributes of the conventional dc and rf glow-discharge techniques. Preliminary mass spectra analyses of both silane and methane glow-discharges demonstrates that ions constitute a significant fraction of the species reaching the film surface. Growth rate analyses suggest that ions play a significant role in the saddle-field glow-discharge deposition of amorphous semiconducting films.

  20. The glow discharge as an atomization and ionization device

    SciTech Connect

    Harrison, W.W.

    1990-01-01

    All of our projects involve the glow discharge source as our basic research focus. Our primary effort is glow discharge mass spectrometry, but we frequently use complementary procedures such as atomic absorption and atomic emission in the glow discharge to obtain useful information about plasma processes. Our overall goal is to gain a better understanding of the glow discharge and to bring it to bear on real analytical problems.

  1. A. C. Stark effect on the 4713 A line emitted by a helium glow discharge in the field of a multimode T.E.A. CO2 laser (*)

    E-print Network

    Paris-Sud XI, Université de

    'amplitude des modes du champ laser. Abstract 2014 In a helium glow discharge, the A. C. Stark shift of the 4 3S1875 A. C. Stark effect on the 4713 A line emitted by a helium glow discharge in the field of a multimode T.E.A. CO2 laser (*) B. Dubreuil, P. Pignolet, A. Catherinot and P. Davy Groupe de Recherches sur

  2. A GLOWING POOL OF LIGHT

    NASA Technical Reports Server (NTRS)

    2002-01-01

    NGC 3132 is a striking example of a planetary nebula. This expanding cloud of gas, surrounding a dying star, is known to amateur astronomers in the southern hemisphere as the 'Eight-Burst' or the 'Southern Ring' Nebula. The name 'planetary nebula' refers only to the round shape that many of these objects show when examined through a small visual telescope. In reality, these nebulae have little or nothing to do with planets, but are instead huge shells of gas ejected by stars as they near the ends of their lifetimes. NGC 3132 is nearly half a light year in diameter, and at a distance of about 2000 light years is one of the nearer known planetary nebulae. The gases are expanding away from the central star at a speed of 9 miles per second. This image, captured by NASA's Hubble Space Telescope, clearly shows two stars near the center of the nebula, a bright white one, and an adjacent, fainter companion to its upper right. (A third, unrelated star lies near the edge of the nebula.) The faint partner is actually the star that has ejected the nebula. This star is now smaller than our own Sun, but extremely hot. The flood of ultraviolet radiation from its surface makes the surrounding gases glow through fluorescence. The brighter star is in an earlier stage of stellar evolution, but in the future it will probably eject its own planetary nebula. In the Heritage Team's rendition of the Hubble image, the colors were chosen to represent the temperature of the gases. Blue represents the hottest gas, which is confined to the inner region of the nebula. Red represents the coolest gas, at the outer edge. The Hubble image also reveals a host of filaments, including one long one that resembles a waistband, made out of dust particles which have condensed out of the expanding gases. The dust particles are rich in elements such as carbon. Eons from now, these particles may be incorporated into new stars and planets when they form from interstellar gas and dust. Our own Sun may eject a similar planetary nebula some 6 billion years from now. Credit: Hubble Heritage Team (STScI/AURA/NASA)

  3. Positive column contraction for a dc glow discharge in CF4

    NASA Astrophysics Data System (ADS)

    Lisovskiy, Valeriy; Pelustka, Olga; Koval, Veronika

    2011-10-01

    This paper studies in experiment the diffusion and contracted modes of dc glow discharge in CF4. The existence region for the contracted mode with inter-electrode gap unchanged is found to be limited from the low-pressure side, this boundary being multi-valued. A contracted column establishes in a stratified positive column with current increasing and gas pressure fixed. However with subsequent current increase the length of the positive column decreases (with simultaneous considerable expansion of the negative glow and dark Faraday space), and contraction vanishes. At higher pressure the current increase does not lead to contraction vanishing. Similar multi-valued region exists from the narrow gap side when the inter-electrode gap changes with gas pressure fixed.

  4. Paschen law for argon glow discharge

    Microsoft Academic Search

    C Torres; P G Reyes; F Castillo; H Martínez

    2012-01-01

    Electric discharge between two electrically charged surfaces occurs at a well-defined, gas-dependent combination of atmospheric pressure and the distance between those surfaces, as described by Paschen's law. The understanding of when the discharge will occur in an Ar discharge is essential basic knowledge. A glow discharge apparatus was used in this experiment of Ar discharge at a pressure range between

  5. Striations in an ethyl alcohol glow discharge

    NASA Astrophysics Data System (ADS)

    Reyes, P. G.; Gómez, A.; Torres, C.; Martínez, H.; Castillo, F.; Vergara, J.

    2015-03-01

    This research shows the behavior of striations in glow discharge generated with high purity ethyl alcohol at a pressure of 0.6 Torr. This paper present the number of striations as a function of the of current and voltage discharge.

  6. Parametric Investigations of an Atmospheric pressure Uniform Glow Discharge in helium

    NASA Astrophysics Data System (ADS)

    Ben Gadri, Rami

    1997-11-01

    In the cold plasma processing field, applications of the atmospheric pressure uniform glow discharge are numerous. Among them one can mention the increase of the surface energy of materials, the cleaning and etching of surfaces, and the decontamination and sterilization. The development of the glow regime at atmospheric pressure permits to avoid the technical and economical drawbacks of low pressure glow discharge systems. It also increases the efficiency of the surface treatment as compared to the corona discharge. In these conditions, a glow regime is obtained and studied in particular experimental conditions. The working gas is helium, the frequency in the range 1-20 kHz, the gap distance of some mm and the metallic electrodes are covered by a dielectric layer. The current is characterized by one peak per half cycle and is typically in the range of a few tens of mA. Since this discharge involves complex nonlinear processes and is sensitive to the variation of its parameters, detailed experimental (Ph. Decomps (1996), PhD thesis, Universite Paul Sabatier Toulouse France, No d'ordre 2538.) and numerical studies, covering wide ranges of system parameters, were required. These investigations allowed the determination of the optimal operating conditions for which the discharge remains of the glow type, and therefore induces a better surface treatment. In this paper the detailed theory ( Ben Gadri R., Rabehi A., Massines F. and Segur P. (1994), XIIth Eur. Sect. Conf. on the At. & Mol. Phy. of Ionized Gases, The Netherlands, 23-26 August, pp. 228-229.) of the one dimensional f luid model and a parametric study of the discharge characteristics are presented. A particular attention will be given to the influence of the different system parameters on the operational mode of the discharge.

  7. On the Shuttle glow (the plasma alternative)

    Microsoft Academic Search

    K. Papadopoulos

    1984-01-01

    It is shown that the anomalous glow observed in the recent Space Shuttle flights can be attributed to a combination of beam plasma discharge and critical ionization phenomena. While the Shuttle velocity (approximately 8 km\\/s) is below the critical ionization velocity, which for oxygen is 12.7 km\\/s, specular reflection of a small fraction (2-3 percent) of ambient ions forms an

  8. Use of glow discharge in fluidized beds

    NASA Technical Reports Server (NTRS)

    Wydeven, T.; Wood, P. C.; Ballou, E. V.; Spitze, L. A. (inventor)

    1981-01-01

    Static charges and agglomerization of particles in a fluidized bed systems are minimized by maintaining in at least part of the bed a radio frequency glow discharge. This approach is eminently suitable for processes in which the conventional charge removing agents, i.e., moisture or conductive particle coatings, cannot be used. The technique is applied here to the disproportionation of calcium peroxide diperoxyhydrate to yield calcium superoxide, an exceptionally water and heat sensitive reaction.

  9. Optogalvanic effects in the obstructed glow discharge

    Microsoft Academic Search

    D. K. Doughty; J. E. Lawler

    1983-01-01

    An anomalously strong 594.5-nm optogalvanic effect is observed in an obstructed glow discharge in 1.0 Torr of Ne occurring between plane parallel Al electrodes separated by 1.0 cm. The absolute size of a steady-state optogalvanic effect is characterized by a dimensionless ratio of the change in power delivered to the load resistor over the absorbed laser power. A ratio of

  10. The One Atmosphere Uniform Glow Discharge Plasma (OAUGDP) as a classical normal glow discharge

    SciTech Connect

    Gadri, R.B.; Sherman, D.M.; Chen, Z.; Karakaya, F.; Roth, J.R.

    1999-07-01

    The One Atmosphere Uniform Glow Discharge Plasma (OAUGDP) operating in air and other gases, has been recently developed at the UTK Plasma Sciences Laboratory and is proprietary to the University of Tennessee. The plasma is driven at low RF frequency, on the order of a few kilohertz, and is formed in a relatively large gap (several mm in air), between plane parallel insulated metal electrodes. For the proper values of gap distance, RF driving frequency, and rms voltage, the OAUGDP operates uniformly, without producing filamentary microdischarges, and its physical characteristics are, in spite of the high pressure, surprisingly analogous to those observed in a normal DC glow discharge. Numerical simulations and experimental time-resolved photographs show that al the features of the classical normal glow discharge are present between the instantaneous cathode and anode: the cathode dark space, a linear electric field in the cathode region obeying Aston's law, the negative glow, the Faraday dark space, and the positive column. The glow discharge nature of the OAUGDP is significant because normal glow discharges operate very efficiently as plasma sources at or near the Stoletow point where the energy cost of generating an ion-electron pair in air is only 81 eV. In other atmospheric plasmas, such as arcs, this energy cost can be at least 10 KeV per ion-electron pair. The authors have developed a variety of configurations for the electrodes which permits both large and small processing volumes and allows a large range of applications to be accommodated. The electrical and physical characteristics of the OAUGDP will be presented.

  11. Effect of cathode surface area and separately stabilized cathodes on high power glow discharges for CO/sub 2/ laser excitation

    SciTech Connect

    Evans, D.R.; Harry, J.E.

    1988-03-01

    Results are presented which indicate the importance of the cathode surface area and the advantage of using separately stabilized cathodes for the excitation of high power CO/sub 2/ lasers. The results indicate that operation of a glow discharge with multiple cathodes of adequate surface area enables operation in the abnormal glow region at higher currents than with a single cathode of the same total surface area. Increase in the current at which the glow-to-arc transition occurs, improved stability, improved utilization of the laser cavity in the electrode region, and a wide range of variation of discharge current are also obtained using multiple cathodes. Large surface area multiple cathodes have been successfully demonstrated in a new high power fast axial flow CO/sub 2/ laser using a single discharge tube operating at discharge currents of up to 1.8 A corresponding to laser output powers of up to 5 kW.

  12. Partially constricted glow discharge in an argon-nitrogen mixture

    SciTech Connect

    Ionikh, Yu. Z.; Meshchanov, A. V.; Petrov, F. B. [Fock Institute of Physics, St. Petersburg State University (Russian Federation); Dyatko, N. A.; Napartovich, A. P. [Troitsk Institute for Innovation and Fusion Research (Russian Federation)

    2008-10-15

    The characteristics of a glow discharge in Ar:N{sub 2} mixtures with a low content of nitrogen (0.02-1%) are studied experimentally. Most studies were performed at pressures higher than 10 Torr, at which the discharge constriction goes by a jump and the hysteresis effect is well pronounced. It is found that the time during which the discharge switches from the diffuse to the constricted mode (and back) can reach {approx}1 s. The transition between these modes begins with the development of a constriction at one end of the positive column. Then, the constricted part of the discharge extends toward the other end until it occupies the entire column. The reverse transition occurs in a similar way. By varying the parameters of the electric circuit during the transition, the constriction front can be stopped to form a steady-state partially constricted discharge. It is shown that this type of discharge corresponds to points lying inside the hysteresis loop of the conventional I-V characteristic measured without affecting the discharge during a transition. A comparative analysis of the discharge characteristics in Ar:N{sub 2} mixtures and in pure argon is performed.

  13. The one atmosphere uniform glow discharge plasma (OAUGDP) as a classical normal glow discharge

    Microsoft Academic Search

    R. B. Gadri; D. M. Sherman; Zhiyu Chen; F. Karakaya; J. R. Roth

    1999-01-01

    Summary form only given, as follows. The one atmosphere uniform glow discharge plasma (OAUGDP) operating in air and other gases, has been recently developed at the UTK Plasma Sciences Laboratory and is proprietary to the University of Tennessee. The plasma is driven at low RF frequency, on the order of a few kilohertz, and is formed in a relatively large

  14. Atmospheric glow discharge plasmas using a microhollow cathode device

    Microsoft Academic Search

    Adam Lodes; Randy Curry

    2009-01-01

    Glow discharges are known to have relatively high electron densities even while maintaining stability. Applications of these discharges are numerous and include plasma reflectors and absorbers of electromagnetic radiation, surface treatment, thin film deposition and gas lasers. Microhollow cathode devices have been shown to be excellent high electron density (up to 1016\\/cm3) sources of glow plasma atmospheric air discharges. Under

  15. Glow discharge based device for solving mazes

    NASA Astrophysics Data System (ADS)

    Dubinov, Alexander E.; Maksimov, Artem N.; Mironenko, Maxim S.; Pylayev, Nikolay A.; Selemir, Victor D.

    2014-09-01

    A glow discharge based device for solving mazes has been designed and tested. The device consists of a gas discharge chamber and maze-transformer of radial-azimuth type. It allows changing of the maze pattern in a short period of time (within several minutes). The device has been tested with low pressure air. Once switched on, a glow discharge has been shown to find the shortest way through the maze from the very first attempt, even if there is a section with potential barrier for electrons on the way. It has been found that ionization waves (striations) can be excited in the maze along the length of the plasma channel. The dependancy of discharge voltage on the length of the optimal path through the maze has been measured. A reduction in discharge voltage with one or two potential barriers present has been found and explained. The dependency of the magnitude of discharge ignition voltage on the length of the optimal path through the maze has been measured. The reduction of the ignition voltage with the presence of one or two potential barriers has been observed and explained.

  16. Glow discharge based device for solving mazes

    SciTech Connect

    Dubinov, Alexander E., E-mail: dubinov-ae@yandex.ru; Mironenko, Maxim S.; Selemir, Victor D. [Russian Federal Nuclear Center ? All-Russian Scientific and Research Institute of Experimental Physics (RFNC-VNIIEF), Sarov, Nizhni Novgorod region 607188 (Russian Federation); Sarov Institute of Physics and Technology (SarFTI) of National Research Nuclear University “MEPhI,” Sarov, Nizhni Novgorod region 607188 (Russian Federation); Maksimov, Artem N.; Pylayev, Nikolay A. [Russian Federal Nuclear Center ? All-Russian Scientific and Research Institute of Experimental Physics (RFNC-VNIIEF), Sarov, Nizhni Novgorod region 607188 (Russian Federation)

    2014-09-15

    A glow discharge based device for solving mazes has been designed and tested. The device consists of a gas discharge chamber and maze-transformer of radial-azimuth type. It allows changing of the maze pattern in a short period of time (within several minutes). The device has been tested with low pressure air. Once switched on, a glow discharge has been shown to find the shortest way through the maze from the very first attempt, even if there is a section with potential barrier for electrons on the way. It has been found that ionization waves (striations) can be excited in the maze along the length of the plasma channel. The dependancy of discharge voltage on the length of the optimal path through the maze has been measured. A reduction in discharge voltage with one or two potential barriers present has been found and explained. The dependency of the magnitude of discharge ignition voltage on the length of the optimal path through the maze has been measured. The reduction of the ignition voltage with the presence of one or two potential barriers has been observed and explained.

  17. Electron kinetic effects in atmospheric dielectric-barrier glow discharges

    SciTech Connect

    Zhu, X.M.; Kong, M.G. [Department of Electronic and Electrical Engineering Loughborough University, Ashby Road, Leicestershire LE11 3TU (United Kingdom)

    2005-04-15

    Large-volume atmospheric dielectric-barrier discharges (DBD) are particularly useful for processing applications when they operate in their homogeneous mode. A vast majority of their theoretical studies is currently based on the hydrodynamic treatment in which electrons are assumed to be in equilibrium with the local electric field. Recognizing that this assumption is incorrect in the sheath region, we report the development of an electron-hybrid model to treat electrons kinetically and all other particles hydrodynamically. Through numerical examples, it is shown that the mainstream hydrodynamic model underestimates gas ionization and discharge current. Using the hybrid model, it is demonstrated that variation in the amplitude of the applied voltage does not significantly alter sheath characteristics in terms of the electric field and the electron mean energy. Also gas ionization in atmospheric DBD is found to be significant only over a short timescale of 1 {mu}s. Compared with dc atmospheric pressure glow discharges, atmospheric DBD are shown to have a smaller electron mean energy and a larger sheath thickness.

  18. Paschen law for argon glow discharge

    NASA Astrophysics Data System (ADS)

    Torres, C.; Reyes, P. G.; Castillo, F.; Martínez, H.

    2012-06-01

    Electric discharge between two electrically charged surfaces occurs at a well-defined, gas-dependent combination of atmospheric pressure and the distance between those surfaces, as described by Paschen's law. The understanding of when the discharge will occur in an Ar discharge is essential basic knowledge. A glow discharge apparatus was used in this experiment of Ar discharge at a pressure range between 2.0 Torr and 12 Torr, a power of 20 W and 40 l/min flow rate of gases. The optical emission spectroscopy was carried out in the wavelength range of 200 to 1100 nm. Here, we present experimentally measured plasma Paschen curves for Ar gas and compare our results of breakdown voltages with the literature. The minimum voltage measured for a discharge in Ar atmosphere was 215 ± 2.2 at 0.7 Torr-cm, which agree with previous measurements.

  19. "Decoking" of a "coked" zeolite catalyst in a glow discharge.

    PubMed

    Khan, M A; Al-Jalal, A A; Bakhtiari, I A

    2003-09-01

    "Decoking" of a "coked" zeolite catalyst in a glow discharge in oxygen is investigated. The "decoking" process involves reactions of atomic oxygen (O atoms) with "coke" and yields gases such as CO, CO(2) as well as other gaseous products that could be easily pumped out. Three different modes of discharge were investigated including a static mode, a flowing-gas mode, and a periodic-purge mode where the oxygen and other gaseous products of the discharge were replaced by fresh O(2)gas after short but regular intervals of time. In some cases, additional heating was also used to provide base temperatures of the order of 100 degrees C to facilitate penetration of oxygen atoms into the inner layers and cages of the zeolite catalyst. This paper presents some results of spectroscopic analytical techniques used to monitor the atomization of oxygen, oxidation of "coke", and to confirm the process of "decoking". More specifically, radiation emission on the 3 s (5)S- 3p (5)P transitions of O around 777.2-777.5 nm were selected for monitoring the atomization of O(2). On the other hand, X-ray photo-electron spectroscopy (XPS) was used to determine the amount of residual carbon and extent of "decoking". Furthermore, evolution of CO and CO(2) gases as a function of time was systematically monitored in real time. For CO, the 451.1 nm band head belonging to the B(1) Sigma - A(1) Pi bands of the Angstrom system of the CO spectrum was used, while for CO(2), the band head at 353.4 nm belonging to the CO(2)(+) spectrum was used. The rates of evolution of CO and CO(2) were related to the rate of "decoking" of the catalyst. It is noted that in the periodic-purge mode, about 63% of the total yield of CO from a given sample of the catalyst appears in the first 3-min exposure to discharge whereas it takes up to 15 min to remove nearly 94% of the removable carbon under our experimental conditions. PMID:12861433

  20. Organic thin film deposition in atmospheric pressure glow discharge

    NASA Astrophysics Data System (ADS)

    Okazaki, S.; Kogoma, M.; Yokoyama, T.; Kodama, M.; Nomiyama, H.; Ichinohe, K.

    1996-01-01

    The stabilization of a homogeneous glow discharge at atmospheric pressure has been studied since 1987. On flat surfaces, various plasma surface treatments and film depositions at atmospheric pressure have been examined. A practical application of the atmospheric pressure glow plasma on inner surfaces of flexible polyvinyl chloride tubes was tested for thin film deposition of polytetrafluoroethylene. Deposited film surfaces were characterized by ESCA and FT-IR/ATR measurements. Also SEM observation was done for platelet adhesion on the plasma treated polyvinyl chloride surface. These results showed remarkable enhancement in the inhibition to platelet adhesion on the inner surface of PVC tube, and homogeneous organic film deposition was confirmed. The deposition mechanism of polytetrafluoroethylene film in atmospheric pressure glow plasma is the same as the mechanism of film formation in the low pressure glow plasma, except for radical formation source.

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

    NASA Technical Reports Server (NTRS)

    Swenson, G.

    1999-01-01

    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.

  2. Glow phenomenon surrounding the vertical stabilizer and OMS pods

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This 35mm frame, photographed as the Space Shuttle Columbia was orbiting Earth during a 'night' pass, documents the glow phenomenon surrounding the vertical stabilizer and the Orbital Maneuvering System (OMS) pods of the spacecraft.

  3. Stratified-charge glow plug ignition engine experiments. Topical report

    Microsoft Academic Search

    R. H. Thring; J. A. Leet

    1991-01-01

    An investigation was conducted to study the feasibility of operating a natural gas two-stroke engine using glow plug ignition with very lean mixtures. The term Stratified-Charge Glow Plus Ignition (SCGI) was coined to describe the engine. A JLO DL 365 single-cylinder, two-stroke, diesel engine was converted first to a natural gas fueled spark-ignited engine for the baseline tests, and then

  4. Studies of the cathode region of the dc glow discharge

    SciTech Connect

    Den Hartog, E.A.

    1989-01-01

    Laser-based spectroscopic diagnostics are employed to gain an increased understanding of the cathode region of a dc helium glow discharge. A pair of diagnostics are used to determine the density (n{sub e}) and temperature (T{sub e}) of low energy electrons confined in the negative glow. The first diagnostic is based on the observed suppression of 2{sup 1}S metastables in the negative glow due to electron collisions. The reaction primarily responsible for the suppression is the metastable spin conversion reaction which converts 2{sup 1}S metastables to 2{sup 3}S metastables. 2{sup 1}S and 2{sup 3}S metastable densities and 2{sup 1}P resonant atom densities are mapped as a function of position, and the maps are analyzed to determine a relation between n{sub e} and T{sub e}. A second relation between n{sub e} and T{sub e} is determined by measuring the electron impact transfer rate between Rydberg levels. The intersection of the two relations yields n{sub e} and T{sub e} for the low energy electrons in the negative glow. Empirical determinations of the current balance at the cathode surface and metastable production are compared to results of Monte Carlo simulations. The current balance comparison leads to the prediction of a field reversal at the cathode fall-negative glow boundary. As a consequence of this field reversal a simple model of the negative glow is suggested, in which the plasma in the negative glow diffuses toward the anode in an ambipolar-like process. Ion production in the negative glow is determined from Monte Carlo simulations. An equation is written balancing production and diffusion losses. This equation is written balancing production and diffusion losses. This equation leads to a third relation between n{sub e} and T{sub e} which is compared to the earlier results.

  5. Mass Spectrometry of Ions in Glow Discharges. V. Oxygen

    Microsoft Academic Search

    P. F. Knewstubb; P. H. Dawson; A. W. Tickner

    1963-01-01

    OSITIVE ions from the negative glow and Faraday dark space of a dc glow discharge in oxygen (purity 99.7%, main impurity-nitrogen) were sampled and analyzed with a mass spectrometer as described in earlier papers.1.2 Figure 1 shows the ions observed from a typical discharge. Because of the long Faraday dark space in oxygen discharges it was not possible to sample

  6. Characterization of a dc atmospheric pressure normal glow discharge

    Microsoft Academic Search

    David Staack; Bakhtier Farouk; Alexander Gutsol; Alexander Fridman

    2005-01-01

    Atmospheric pressure dc glow discharges were generated between a thin cylindrical anode and a flat cathode. Voltage-current characteristics, visualization of the discharge and estimations of the current density indicate that the discharge is operating in the normal glow regime. Emission spectroscopy and gas temperature measurements using the 2nd positive band of N2 indicate that the discharge forms a non-equilibirum plasma.

  7. Effect of Glow Discharge on Laser-Vaporized Deposition of Thin Films and Activation Energy Measurement of the Copper-Oxygen Reaction in Glow Discharge

    Microsoft Academic Search

    Shuhua Zhang

    1993-01-01

    A ruby laser was used to deposit Cu films on a carbon substrate with or without DC glow discharge. RBS measurement was used to examine the composition of the films. The oxygen content is enhanced by the glow discharge and is linearly dependent on laser pulse energy, oxygen partial pressure, and glow discharge voltage in the region of 2-8 joules,

  8. The measurements of vehicle glow on the Space Shuttle

    NASA Technical Reports Server (NTRS)

    Mende, S. B.; Banks, P. M.; Nobles, R.; Garriott, O. K.; Hoffman, J.

    1983-01-01

    From the combined data set of glow observations on STS-3, STS-4 and STS-5 some of the properties of the shuttle glow were observed. Comparison of the STS-3 (240 km) and STS-5 (305 km) photographs show that the intensity of the glow is about a factor of 3.5 brighter on the low altitude (STS-3) flight. The orbiter was purposely rotated about the x axis in an experiment on STS-5 to observe the dependence of the intensity on the angle of incidence between the spacecraft surface normal and the velocity vector. For a relatively large angle between the velocity vector and the surface normal there is an appreciable glow, provided the surface is not shadowed by some other spacecraft structure. As the angle becomes less the glow intensifies. The grating experiments (STS-4 photography only, STS-5 image intensifier photography) provided a preliminary low resolution spectra of the spacecraft glow. Accurate wavelength calibrations of the STS-5 instrument permitted measuring of the spectrum and intensity of the Earth's airglow.

  9. Abnormal glow discharge in crossed electric and magnetic fields in the presence of reactive gas

    NASA Astrophysics Data System (ADS)

    Luchkin, A. G.; Kashapov, N. F.; Luchkin, G. S.

    2013-12-01

    The results of investigations of the low-temperature plasma at process of reactive magnetron sputtering of Ti target in the presence of reactive gas are described. Discharge volt-ampere characteristics for different schemas of reactive gas input are build. Optimal regimes of making strengthening coatings are defined. TiOx (0 < x < 2) strengthening coatings at plastics are made. Coatings showed high consumer qualities.

  10. Lunar horizon glow and the Clementine mission

    NASA Technical Reports Server (NTRS)

    Zook, H. A.; Potter, A. E.

    1994-01-01

    The Clementine spacecraft is to be launched into Earth orbit in late January for subsequent insertion into lunar orbit in late February, 1994. There, its primary mission is to produce -- over a period of about two months -- a new photographic map of the entire surface of the Moon; this will be done, in a variety of wavelengths and spatial resolutions, in a manner greatly superior to that previously accomplished for the whole Moon. It will then go on to fly by and photograph the asteroid Geographos. A secondary goal that has been accepted for this mission is to take a series of photographs designed to capture images of, and determine the brightness and extent of, the Lunar Horizon Glow (LHG). One form of LHG is caused by the solar stimulation of emission from Na and K atoms in the lunar exosphere. The scale height of this exosphere is of the order of 100 km. There are also brighter LHG components, with much smaller scale heights, that appear to be caused by scattered off of an exospheric lunar dust cloud.

  11. Glow discharge conditioning of the PDX vacuum vessel

    SciTech Connect

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

    1980-03-01

    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.

  12. Space structure of the glow discharge with free side boundary

    SciTech Connect

    Yatsenko, N.A. [Institute of Problems in Mechanics, Moscow (Russian Federation)

    1995-12-31

    The main purpose of this work is to reveal physical reasons, which are responsible for the formation of space structure of glow type discharge with free side boundary, both in DC and in RF electric fields. By now extensive experimental material have been accumulated in discharge physics. Also many theoretical models have been proposed for describing separate parts of discharge with the cold electrodes (cathode and anode regions, positive column and transition zones - glow luminescence and Farraday`s dark space of DC-discharge, electrode regions and plasma column of RF capacitive discharge). As this takes place, the majority of known works are devoted to some one part of gas discharge - positive column, electrode regions, transition zones and so on. At the same time just now we don`t know anything about space structure of free, steady-state gas discharge of glow type, as a whole, especially when the pressure p {much_gt} 1 Torr.

  13. Investigation of helium ion production in constricted direct current plasma ion source with layered-glows.

    PubMed

    Lee, Yuna; Chung, Kyoung-Jae; Park, Yeong-Shin; Hwang, Y S

    2014-02-01

    Generation of helium ions is experimentally investigated with a constricted direct current (DC) plasma ion source operated at layered-glow mode, in which electrons could be accelerated through multiple potential structures so as to generate helium ions including He(2+) by successive ionization collisions in front of an extraction aperture. The helium discharge is sustained with the formation of a couple of stable layers and the plasma ball with high density is created near the extraction aperture at the operational pressure down to 0.6 Torr with concave cathodes. The ion beam current extracted with an extraction voltage of 5 kV is observed to be proportional to the discharge current and inversely proportional to the operating pressure, showing high current density of 130 mA/cm(2) and power density of 0.52 mA/cm(2)/W. He(2+) ions, which were predicted to be able to exist due to multiple-layer potential structure, are not observed. Simple calculation on production of He(2+) ions inside the plasma ball reveals that reduced operating pressure and increased cathode area will help to generate He(2+) ions with the layered-glow DC discharge. PMID:24593635

  14. Investigation of helium ion production in constricted direct current plasma ion source with layered-glows

    NASA Astrophysics Data System (ADS)

    Lee, Yuna; Chung, Kyoung-Jae; Park, Yeong-Shin; Hwang, Y. S.

    2014-02-01

    Generation of helium ions is experimentally investigated with a constricted direct current (DC) plasma ion source operated at layered-glow mode, in which electrons could be accelerated through multiple potential structures so as to generate helium ions including He2+ by successive ionization collisions in front of an extraction aperture. The helium discharge is sustained with the formation of a couple of stable layers and the plasma ball with high density is created near the extraction aperture at the operational pressure down to 0.6 Torr with concave cathodes. The ion beam current extracted with an extraction voltage of 5 kV is observed to be proportional to the discharge current and inversely proportional to the operating pressure, showing high current density of 130 mA/cm2 and power density of 0.52 mA/cm2/W. He2+ ions, which were predicted to be able to exist due to multiple-layer potential structure, are not observed. Simple calculation on production of He2+ ions inside the plasma ball reveals that reduced operating pressure and increased cathode area will help to generate He2+ ions with the layered-glow DC discharge.

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

    NASA Astrophysics Data System (ADS)

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

    2012-08-01

    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.

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

    SciTech Connect

    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

    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.

  17. A model for particulate contaminated glow discharges Michael J. t&Caughey and Mark J. Kushner

    E-print Network

    Kushner, Mark

    of particu- lates in radio frequency (rf) silane glow discharges using laser light scattering.5 They foundA model for particulate contaminated glow discharges Michael J. t&Caughey and Mark J. Kushner, Illinois 61801 (Received 20 December 1990; accepted for publication 13 February 1991) Glow discharges

  18. Dynamics of pulse phenomena in helium dielectric-barrier atmospheric-pressure glow discharges

    E-print Network

    Raja, Laxminarayan L.

    Dynamics of pulse phenomena in helium dielectric-barrier atmospheric-pressure glow discharges of pulse phenomena in conventional parallel-plate dielectric-barrier controlled atmospheric-pressure glow. DOI: 10.1063/1.1625414 I. INTRODUCTION There is rapidly growing interest in atmospheric- pressure glow

  19. Role of trace impurities in large-volume noble gas atmospheric-pressure glow discharges

    E-print Network

    Raja, Laxminarayan L.

    Role of trace impurities in large-volume noble gas atmospheric-pressure glow discharges Xiaohui 2002 A computational study of capacitively coupled atmospheric-pressure glow discharges in high atmospheric-pressure glow discharges. © 2002 American Institute of Physics. DOI: 10.1063/1.1497445 Several

  20. Accumulation of products of ferroelectric target sputtering in the plasma of an RF glow discharge

    NASA Astrophysics Data System (ADS)

    Zinchenko, S. P.; Tolmachev, G. N.

    2013-12-01

    The zone of macroparticle accumulation was revealed based on laser radiation scattering at copper vapor in the plasma of an RF glow discharge upon sputtering of multicomponent nanosize ferroelectric films. This zone was detected at the interface between the negative glow and the dark cathode space of the glow discharge. It is supposed that these particles are charged products of ferroelectric target sputtering.

  1. Nonthermal glow of thin metal plates and films exposed to Pulsed Laser Radiation

    Microsoft Academic Search

    A. F. Banishev; V. Ya. Panchenko; A. V. Shishkov

    2003-01-01

    Nonthermal glow excited in molybdenum plates and films as a result of temperature stresses arising under the action of laser\\u000a pulses is investigated. A relation between the glow excitation threshold and the sample thickness is established. A possible\\u000a mechanism of nonthermal glow is discussed.

  2. The fractal dimension of ionization cascades in the glow discharge

    NASA Astrophysics Data System (ADS)

    Smith, Reginald D.

    2005-04-01

    The glow discharge's main ionization breakdown processes have been understood for about one hundred years. The glow discharge, however, still remains an area of active research in relation to pattern formation and far-from-equilibrium systems. The primary and secondary ionization processes can be mathematically modelled as general branching processes. Not only is the Townsend breakdown criterion obtained but the ionization avalanche can be characterized as a branching set with a unique Hausdorff fractal dimension. These fractal dimensions can be utilized in applications using similarity principles and Paschen's Law.

  3. Role of metastable atoms in glow discharge ionization processes

    SciTech Connect

    Hess, K.R.; Harrison, W.W.

    1988-04-01

    Ionization processes have been studied in a glow discharge using neon and argon as discharge gases. A tunable laser served to depopulate metastable atom populations, and the effects were followed by optical galvanic spectroscopy and mass spectrometry. In the neon discharge, depopulation of the metastables caused a general reduction in all measured ion signals, while similar studies with argon showed that many species with ionization potentials greater than the metastable energies of argon were not affected by laser depopulation. These results provide evidence for the role of Penning ionization in the glow discharge.

  4. A New Pulsed Glow Discharge Source With Enhanced Ion Extraction for Small Non-Conductive Samples or Atmospheric Sampling

    SciTech Connect

    Jackson, Glen P. [Ohio University, Athens; Haire, Richard {Dick} G [ORNL; Duckworth, Douglas {Doug} C [ORNL

    2003-04-01

    An ionization source designed to efficiently utilize sub-milligram quantities of electrically non-conducting compounds (i.e. oxides) for prolonged periods of mass spectrometric analysis is described. The source is coupled to a quadrupole ion trap mass spectrometer in this report, but could readily be modified for alternative types of mass spectrometers. The coaxial-design glow discharge ion source is unique in that it incorporates a focusing lens behind the discharge surface to steer ions towards the ion sampling plate and thereby improve sensitivity. Non-conducting oxide samples are infused in indium and set in one end of an electrically conductive rod, to which the voltage is applied. Transmission efficiency is sufficient to allow the measurement of isotopes of tungsten from a tungsten rod using glow discharge pulse widths as narrow as 2 {micro}s, which is on the order of single-atom layer sputtering. The sputtering and ionization processes occurring in the discharge produces mainly atomic metal ions, regardless of the chemical form of the metals in the samples. This latter aspect is particularly useful for intended applications involving actinide samples, and allows a minimal amount of sample handling. In a second application, a metal capillary is used in place of the rod to create an atmospheric sampling glow discharge. In this mode, the ion-focusing lens was also found to enhance ion signals arising from volatile vapors entering the discharge from the capillary.

  5. Synchronization between two coupled direct current glow discharge plasma sources

    NASA Astrophysics Data System (ADS)

    Chaubey, Neeraj; Mukherjee, S.; Sekar Iyengar, A. N.; Sen, A.

    2015-02-01

    Experimental results on the nonlinear dynamics of two coupled glow discharge plasma sources are presented. A variety of nonlinear phenomena including frequency synchronization and frequency pulling are observed as the coupling strength is varied. Numerical solutions of a model representation of the experiment consisting of two coupled asymmetric Van der Pol type equations are found to be in good agreement with the observed results.

  6. Metal Mesh Smear Sampling for Glow Discharge Analytical Spectroscopy

    SciTech Connect

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

    2000-06-01

    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.

  7. Role of metastable atoms in glow discharge ionization processes

    Microsoft Academic Search

    K. R. Hess; W. W. Harrison

    1988-01-01

    Ionization processes have been studied in a glow discharge using neon and argon as discharge gases. A tunable laser served to depopulate metastable atom populations, and the effects were followed by optical galvanic spectroscopy and mass spectrometry. In the neon discharge, depopulation of the metastables caused a general reduction in all measured ion signals, while similar studies with argon showed

  8. Optogalvanic spectra of neon and argon in glow discharge lamps.

    PubMed

    Nestor, J R

    1982-11-15

    Optogalvanic spectra of atomic neon and argon have been obtained by irradiating miniature glow discharge lamps with a pulsed, tunable dye laser. The method is shown to be useful for wavelength calibration of tunable lasers, and the resonant lines are cataloged. Two-photon absorption lines in neon are observed when the laser is focused into a small region of the discharge. PMID:20401023

  9. Hopf bifurcations in balance equations of glow discharges

    Microsoft Academic Search

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

    1997-01-01

    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

  10. Degradation of Organics in a Glow Discharge Under Martian Conditions

    NASA Technical Reports Server (NTRS)

    Hintze, P. E.; Calle, L. M.; Calle, C. I.; Buhler, C. R.; Trigwell, S.; Starnes, J. W.; Schuerger, A. C.

    2006-01-01

    The primary objective of this project is to understand the consequences of glow electrical discharges on the chemistry and biology of Mars. The possibility was raised some time ago that the absence of organic material and carbonaceous matter in the Martian soil samples studied by the VikinG Landers might be due in part to an intrinsic atmospheric mechanism such as glow discharge. The high probability for dust interactions during Martian dust storms and dust devils, combined with the cold, dry climate of Mars most likely results in airborne dust that is highly charged. Such high electrostatic potentials generated during dust storms on Earth are not permitted in the low-pressure CO2 environment on Mars; therefore electrostatic energy released in the form of glow discharges is a highly likely phenomenon. Since glow discharge methods are used for cleaning and sterilizing surfaces throughout industry, the idea that dust in the Martian atmosphere undergoes a cleaning action many times over geologic time scales appears to be a plausible one.

  11. NSTX Filament Preionization And Glow Discharge Cleaning Systems

    E-print Network

    NSTX Filament Preionization And Glow Discharge Cleaning Systems H. W. Kugel, W. Blanchard, G. D'Amico, R. Gernhardt, T. Provost Princeton Plasma Physics Laboratory, Princeton University, Princeton NJ operations, and used to reduce volt-sec consumption for February 1999 plasma discharges up to 280 KA

  12. NSTX Filament Preionization And Glow Discharge Cleaning Systems

    E-print Network

    NSTX Filament Preionization And Glow Discharge Cleaning Systems H. W. Kugel, W. Blanchard, G. D'Amico, R. Gernhardt, T. Provost Princeton Plasma Physics Laboratory, Princeton University, Princeton NJ operations, and used to reduce volt­sec consumption for February 1999 plasma discharges up to 280 KA

  13. Mechanism of boriding from pastes in a glow discharge

    SciTech Connect

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

    1987-09-01

    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.

  14. Benzene Dissociation in DC Atmospheric Pressure Air Glow Discharges

    NASA Astrophysics Data System (ADS)

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

    2001-10-01

    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.

  15. Camp GLOW (Girls Leading Our World): Handbook for Volunteers.

    ERIC Educational Resources Information Center

    Peace Corps, Washington, DC. Information Collection and Exchange Div.

    Camp GLOW (Girls Leading Our World) began in Romania in 1995 as a weeklong leadership camp with the purpose of encouraging young women to become active citizens by building their self-esteem and confidence, increasing their self-awareness, and developing their skills in goal-setting, assertiveness, and career and life planning. Since that first…

  16. Renal abnormalities in leprosy.

    PubMed

    Kirsztajn, G M; Nishida, S K; Silva, M S; Ajzen, H; Pereira, A B

    1993-01-01

    We have evaluated laboratory and clinical manifestations of renal disease in 96 patients with leprosy, looking for a sensitive and early marker for detection and possibly follow-up of nephropathy in these patients. Microscopic hematuria was observed in 21.9% of the cases (with dysmorphic erythrocytes in 71.4% of them). Abnormal microalbuminuria and urinary beta 2-microglobulin were found in 15.8 and 19.8% of the cases, respectively. We have observed a high frequency of hematuria, abnormal microalbuminuria and elevation of urinary beta 2-microglobulin in these patients still with normal serum creatinine. PMID:8289988

  17. Stimulated Electromagnetic Emission Indicator of Glow Plasma Discharges from Ionospheric HF Wave Transmissions with HAARP

    NASA Astrophysics Data System (ADS)

    Bernhardt, P. A.; Scales, W.; Briczinski, S. J.; Fu, H.; Mahmoudian, A.; Samimi, A.

    2012-12-01

    High power radio waves resonantly interact with to accelerate electrons for production of artificial aurora and plasma clouds. These plasma clouds are formed when the HF frequency is tuned near a harmonic of the electron cyclotron frequency. At a narrow band resonance, large electrostatic fields are produced below the F-layer and the neutral atmosphere breaks down with a glow plasma discharge. The conditions for this resonance are given by matching the pump wave frequency and wave-number with the sum of daughter frequencies and wave-numbers for several plasma modes. The most likely plasma mode that accelerates the electrons is the electron Bernstein wave in conjunction with an ion acoustic wave. Both upper hybrid and whistler mode waves are also possible sources of electron acceleration. To determine the plasma process for electron acceleration, stimulated electromagnetic emissions are measured using ground receivers in a north-south chain from the HAARP site. Recent observations have shown that broad band spectral lines downshifted from the HF pump frequency are observed when artificial plasma clouds are formed. For HF transmissions are the 2nd, 3rd, and 4th gyro harmonic, the downshifted indicators are found 500 Hz, 20 kHz, and 140 kHz, respectively, from the pump frequency. This Indicator Mode (IM) anticipates that a plasma layer will be formed before it is recorded with an ionosonde or optical imager.

  18. Abnormal Psychology Psychology 280

    E-print Network

    Liu, Taosheng

    1 Abnormal Psychology Psychology 280 1st Summer Session 2013 May 13June 27, 2013 Tuesday" Kalibatseva, M.A. Office: 127B Psychology Building Email: kalibats@msu.edu Phone Psychology PhD program at Michigan State University. I completed my bachelor's dual degree in psychology

  19. Study of short atmospheric pressure dc glow microdischarge in air

    NASA Astrophysics Data System (ADS)

    Kudryavtsev, Anatoly; Bogdanov, Eugene; Chirtsov, Alexander; Emelin, Sergey

    2011-10-01

    The results of experiments and simulations of short (without positive column) atmospheric pressure dc glow discharge in air are presented. We used metal steel electrodes with a gap of 5-100 microns. The experimental voltage-current characteristic's (VAC) have a constant or slightly increasing form at low gap. The most stable microdischarges were burning with a flat cathode and rounded anode, when the length of the discharge is automatically established near the minimum of the Paschen curve by changing their binding on the anode. In this case microdischarge was stable and it had growing VAC. For simulations we used 2D fluid model with kinetic description of electrons. We solved the balance equations for the vibrationally- and the electronically-excited states of a nitrogen and oxygen molecules; nitrogen and oxygen atoms; ozone molecule; and different nitrogen and oxygen ions with different plasmochemical reactions between them. Simulations predicted the main regions of the dc glow discharges including cathode and anode sheath and plasma of negative glow, Faraday dark space and transition region. Gas heating plays an important role in shaping the discharge profiles. The results of experiments and simulations of short (without positive column) atmospheric pressure dc glow discharge in air are presented. We used metal steel electrodes with a gap of 5-100 microns. The experimental voltage-current characteristic's (VAC) have a constant or slightly increasing form at low gap. The most stable microdischarges were burning with a flat cathode and rounded anode, when the length of the discharge is automatically established near the minimum of the Paschen curve by changing their binding on the anode. In this case microdischarge was stable and it had growing VAC. For simulations we used 2D fluid model with kinetic description of electrons. We solved the balance equations for the vibrationally- and the electronically-excited states of a nitrogen and oxygen molecules; nitrogen and oxygen atoms; ozone molecule; and different nitrogen and oxygen ions with different plasmochemical reactions between them. Simulations predicted the main regions of the dc glow discharges including cathode and anode sheath and plasma of negative glow, Faraday dark space and transition region. Gas heating plays an important role in shaping the discharge profiles. This work was supported by the FZP and SPbGU

  20. Pulsed and RF glow discharge in Helium atmosphere

    NASA Astrophysics Data System (ADS)

    Gulati, Pooja; Pal, U. N.; Kumar, N.; Srivastava, V.; Parkash, Ram; Vyas, Vimal

    2012-11-01

    This paper reports the optical and electrical characterization of sinusoidal and pulse glow-discharge plasma in helium. A homogeneous type of discharge has been observed for different operating conditions in helium DBD. The image of discharges makes sure that the diffuse discharge covers the entire surface of the electrodes. Optical emission spectroscopy has been used to determine the main emission lines of the helium glow discharge plasma. The internal plasma parameters of DBDs have been investigated at different operating conditions. It has been observed that the DBDs are becoming more intense with increase in pressure and applied power. The effect of the excitation mechanism on the emission properties and discharge parameters for the helium DBD is studied experimentally and further analysed by using plasma simulation tool OOPIC-Pro.

  1. Radiation effects on ETFE polymer exposed to glow discharge

    NASA Astrophysics Data System (ADS)

    Minamisawa, Renato Amaral; Abidzina, Volha; de Almeida, Adelaide; Budak, Satilmis; Tereshko, I.; Elkin, I.; Ila, Daryush

    2007-08-01

    The polymer ethylenetetrafluoroethylene (ETFE) is composed of alternating ethylene and tetrafluoroethylene segments. Because it has applications in areas such as medical physics and industrial coatings, there is a great interest in surface modification studies of ETFE polymer. When this material is exposed to ionizing radiation it suffers damage that depends on the type, energy and intensity of the irradiation. In order to determine the radiation damage mechanism from exposure to low voltage plasma, ETFE films were exposed to residual gas plasma in glow discharge regime to a fluence of 2 × 10 17 ions/cm 2. Irradiated films were analyzed with optical absorption photospectrometry, Fourier transform infrared (FTIR) and Raman spectroscopy to determine the chemical nature of the structural changes caused by low energy glow discharge.

  2. Glow discharge pretreatment tools for vacuum web coating

    Microsoft Academic Search

    M. Geisler; G. Hoffmann; R. Ludwig; G. Steiniger

    2004-01-01

    In the last few years plasma pre-treatment has been established as a powerful tool to increase the quality in vacuum web coating whereas, the effect of web pre-treatment under atmospheric conditions is declining due to several reasons, glow discharge assisted in line–in vacuo pre-treatment is much more reliable. Two tools for plasma pre-treatment are presented here. Both are easily scalable

  3. Biological surface modification of titanium surfaces using glow discharge plasma

    Microsoft Academic Search

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

    2011-01-01

    To improve the biological activity of titanium, by using of glow discharge plasma (GDP), albumin-grafted titanium disk have\\u000a been implemented and carefully studied. Titanium disks were pre-treated with GDP in an environment filled with argon and allylamine\\u000a gas. Glutaraldehyde was used as a cross-linking agent for albumin grafting. Then, the surface of the albumin-grafted titanium\\u000a was examined using scanning electron

  4. Junction solar cells made with molecular beam glow discharge bombardment

    Microsoft Academic Search

    E. J. Caine; E. J. Charlson

    1984-01-01

    The fabrication and characterization of silicon p-n junction solar cells with various glow discharge, unanalyzed, molecular\\u000a implanted emitter regions is described. Total area simulated air mass one (AM1) power conversion efficiencies without AR coatings\\u000a or back surface fields are at best 8.2% compared to 9.1% for conventionally implanted or POC13 thermally diffused cells on similar substrates. To achieve optimum performance,

  5. Junction solar cells made with molecular beam glow discharge bombardment

    Microsoft Academic Search

    E. J. Caine; E. J. Charlson

    1984-01-01

    The fabrication and characterization of silicon p-n junction solar cells with various glow discharge, unanalyzed, molecular implanted emitter regions is described. Total area simulated air mass one (AM1) power conversion efficiencies without AR coatings or back surface fields are at best 8.2% compared to 9.1% for conventionally implanted or POC13 thermally diffused cells on similar substrates. To achieve optimum performance,

  6. Diode laser absorption measurements of metastable helium in glow discharges

    Microsoft Academic Search

    Michael W. Millard; Perry P. Yaney; Biswa N. Ganguly; Charles A. DeJoseph Jr.

    1998-01-01

    A laser-based technique for accurate measurement of the population density profiles of the 0963-0252\\/7\\/3\\/017\\/img7 helium metastable in a parallel-plate, glow discharge is described. The system utilizes a distributed-Bragg-reflector diode laser operating at 1083 nm to perform absorption measurements on the 0963-0252\\/7\\/3\\/017\\/img8 transitions of helium. The narrow bandwidth (<3 MHz) of the laser permits simultaneous measurement of the line-integrated metastable density

  7. Inception of Snapover and Gas Induced Glow Discharges

    NASA Technical Reports Server (NTRS)

    Galofaro, J. T.; Vayner, B. V.; Degroot, W. A.; Ferguson, D. C.; Thomson, C. D.; Dennison, J. R.; Davies, R. E.

    2000-01-01

    Ground based experiments of the snapover phenomenon were conducted in the large vertical simulation chamber at the Glenn Research Center (GRC) Plasma Interaction Facility (PIF). Two Penning sources provided both argon and xenon plasmas for the experiments. The sources were used to simulate a variety of ionospheric densities pertaining to a spacecraft in a Low Earth Orbital (LEO) environment. Secondary electron emission is believed responsible for dielectric surface charging, and all subsequent snapover phenomena observed. Voltage sweeps of conductor potentials versus collected current were recorded in order to examine the specific charging history of each sample. The average time constant for sample charging was estimated between 25 and 50 seconds for all samples. It appears that current drops off by approximately a factor of 3 over the charging time of the sample. All samples charged in the forward and reverse bias directions, demonstrated hysteresis. Current jumps were only observed in the forward or positive swept voltage direction. There is large dispersion in tile critical snapover potential when repeating sweeps on any one sample. The current ratio for the first snapover region jumps between 2 and 4.6 times, with a standard deviation less than 1.6. Two of the samples showed even larger current ratios. It is believed the second large snapover region is due to sample outgassing. Under certain preset conditions, namely at the higher neutral gas background pressures, a perceptible blue-green glow was observed around the conductor. The glow is believed to be a result of secondary electrons undergoing collisions with an expelled tenuous cloud of gas, that is outgassed from the sample. Spectroscopic measurements of the glow discharge were made in an attempt to identify specific lines contributing to the observed glow.

  8. Mass Spectrometry of Ions in Glow Discharges. IV. Water Vapor

    Microsoft Academic Search

    P. F. KNEWSTUBBt; A. W. Tickner

    1963-01-01

    Ions from the negative glow and Faraday dark space of discharges in water vapor have been analyzed with a mass spectrometer. The ions observed are of the form H3O+·(H2O)n with n=0 to 5. It is shown that the observations are altered by the sampling process to an extent which depends on discharge conditions and is sometimes quite large. This effect

  9. Shock Wave Propagation Measurements in Glow Discharge Plasmas

    Microsoft Academic Search

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

    2006-01-01

    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 tau1\\/4 = 1.4 mus). 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

  10. Exercises to Improve Gait Abnormalities

    MedlinePLUS

    ... Home About Goals Articles Directories Videos Resources Contact Exercises to Improve Gait Abnormalities Home » Article Categories » Exercise and Fitness Font Size: A A A A Exercises to Improve Gait Abnormalities Next Page The manner ...

  11. Abnormal human sex chromosome constitutions

    SciTech Connect

    NONE

    1993-12-31

    Chapter 22, discusses abnormal human sex chromosome constitution. Aneuploidy of X chromosomes with a female phenotype, sex chromosome aneuploidy with a male phenotype, and various abnormalities in X chromosome behavior are described. 31 refs., 2 figs.

  12. Spatial and temporal variability of SWIR air glow measurements

    NASA Astrophysics Data System (ADS)

    Dayton, David; Allen, Jeff; Gonglewski, John; Myers, Mike; Fertig, Gregory; Nolasco, Rudy; Maia, Francisco

    2010-10-01

    It is well known that luminance from photo-chemical reactions of hydroxyl ions in the upper atmosphere (~85 km altitude) produces a significant amount of night time radiation in the short wave infra-red (SWIR) band between 0.9 and 1.7 ?m wave length. This has been demonstrated as an effective illumination source for night time imaging applications. It addition it has been shown that observation of the spatial and temporal variations of the illumination can be used to characterize atmospheric tidal wave actions in the air glow region. These spatiotemporal variations manifest themselves as traveling wave patterns whose period and velocity are related to the wind velocity at 85 km as well as the turbulence induced by atmospheric vertical instabilities. We are interested in studying these phenomena for a variety of reasons. First they can give an insight into upper atmospheric physics, second we would like to understand the variations in order to determine if air glow can be used as a reliable illumination source for night time terrestrial imaging. To that end we have been collecting data on ground irradiance from air glow over the past six months at a site on the island of Kauai. The purpose of this paper is to discuss some initial analysis of this data.

  13. Development of blood compatible materials by glow discharge-treatment

    NASA Astrophysics Data System (ADS)

    Ishikawa, Y.; Sasakawa, S.

    Glow discharge-treatment was applied to preparation of blood compatible materials. Plasticized polyvinylchloride (PVC) which is used for blood bags was treated in the presence of various gases or monomers. Wettability of PVC was modified by the treatment over a wide range. And leakage of plasticizer, di-(2-ethylhexyl)phthalate (DEHP), was prevented. When platelet concentrates were stored in the treated PVC bags, impairment of platelet functions was suppressed by the prevention of DEHP leakage. But platelet adhesion to the surfaces increased by the treatments. Aldehyde groups were grafted on polyethylene film (PE) by glow discharge-treatment in the presence of formaldehyde gas. Although the aldehyde-grafted PE (HCHO-PE) had higher reactivity with platelet than PE after albumin coating, it exhibited excellent antithrombogenicity after blood plasma coating. HCHO-PE adsorbed proteins with almost the same composition as blood plasma, although non-treated PE adsorbed proteins with higher fibinogen/albumin ratio. Segmented-polyurethane which is well known to exhibit good antithrombogenicity, also formed the adsorption layer having composition like that of blood plasma. These results suggest that protein layer adsorbed with blood plasma composition is hardly recognized by platelets. Glow discharge-treatment is a simple and effective method for surface modification of medical polymers.

  14. Synthesis of nanocrystalline carbon nitride films by glow discharge plasma beam deposition

    Microsoft Academic Search

    Wei Hu; Ning Xu; Yi-Qun Sheng; Ting-Wei Zhang; Jian Sun; Jia-Da Wu; Zhi-Feng Ying

    2006-01-01

    Carbon nitride films were deposited on Co\\/Ni-covered Si(100) wafers at room temperature using a dc glow discharge plasma beam deposition method. The glow discharge has been carried out in a mixed gas of nitrogen and methane in different relative proportions and has maintained stable in an glow operating pressure around 30Torr. Scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and

  15. A self-consistent model for negative glow discharge lasers: the hollow cathode helium mercury laser

    Microsoft Academic Search

    Gregory J. Fetzer; Jorge J. Rocca

    1992-01-01

    A model for negative glow metal-vapor ion lasers that self-consistently describes the dynamics of the negative glow and the cathode sheath regions of the discharge has been developed. The model computes the electron energy distribution and the population of relevant excited states in the negative glow self-consistently with the charged particles fluxes and electric field distribution in the cathode sheath.

  16. Experiments with Glow-in-the-Dark Toys: Kinetics of Doped ZnS Phosphorescence

    Microsoft Academic Search

    George C. Lisensky; Manish N. Patel; Megan L. Reich

    1996-01-01

    Many semiconductors exhibit the property of phosphorescence, the phenomenon whereby a material excited by visible or ultraviolet radiation glows (i.e., emits visible light) for a substantial time after the excitation source has been removed. One phosphorescent semiconductor commonly used in glow-in-the dark toys and emergency signs is copper-doped zinc sulfide (ZnS:Cu), a material that produces a yellow-green glow. The study

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

    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.

  18. Spatiotemporal laser perturbation of competing ionization waves in a neon glow discharge

    PubMed

    Weltmann; Koepke; Selcher

    2000-08-01

    The experimental verification of spatiotemporal periodic pulling, a specific but universal phenomenon associated with driven, nonlinear, spatiotemporal systems, is reported as part of a study characterizing the ability of dc and chopped laser light to induce periodic pulling in ionization waves propagating in a neon glow-discharge plasma. The degree to which a single-mode laser beam at a metastable transition of 6401 A (1s(5)-2p(9)) influences the discharge is found to depend on the location and magnitude of the perturbation. Cases of ac (chopping the light) and dc perturbation are presented. In a range of chopping frequencies above and below the ionization wave's undriven frequency, the wave can become synchronized to the perturbation. This entrainment range is shown to depend on the frequency difference between the wave and the perturbation, as well as on the perturbation distance from the cathode. Hysteresis is found in the value of the perturbation frequency associated with transitions into and out of entrainment. Outside of entrainment, periodic pulling of a self-excited, propagating, ionization wave by the laser perturbation is observed. This is a case of frequency pulling, or temporal periodic pulling. Inside of entrainment, the chopped laser light controls the frequency and amplitude of the mode. By properly adjusting the frequency and amplitude of one mode with respect to a second mode, periodic pulling of one ionization wave by the mode-locked, propagating, original ionization wave is demonstrated. This is a case of spatiotemporal pulling, involving both wavelength pulling and frequency pulling. Under proper conditions, competition between temporal and spatiotemporal periodic pulling results in a modulation in the dynamics of the system, a process referred to as dynamics modulation. PMID:11088758

  19. Osmium conductive metal coating for SEM specimen using sublimated osmium tetroxide in negative glow phase of DC glow discharge.

    PubMed

    Tanaka, A

    1994-08-01

    A new method of osmium conductive metal coating for scanning electron microscopy specimens using osmium tetroxide in direct current glow discharge and its apparatus have been devised. Anode and cathode plates are placed in a gas reactor, sublimated osmium tetroxide is introduced, and glow discharge is generated. As a result, the gas between the electrodes instantaneously becomes plasma. At the specimen surface, which is placed in the negative glow phase on the cathode plate, positively ionized osmium molecules are directly adhered and deposited, thereby leaving a completely amorphous metal coating of osmium. As a result, the formed coating precisely matched the fine structure of the specimen surface, and even when irradiated with a strong electron beam was free of heat damage, electrification and contamination. The secondary electron emission efficiency of the coating was also good. Furthermore, no granularity of the film surface was observed even when viewed at a high magnification. In this way, a superior osmium conductive metal coating was obtained. PMID:7996076

  20. Abnormal ionization in sonoluminescence

    NASA Astrophysics Data System (ADS)

    Zhang, Wen-Juan; An, Yu

    2015-04-01

    Sonoluminescence is a complex phenomenon, the mechanism of which remains unclear. The present study reveals that an abnormal ionization process is likely to be present in the sonoluminescing bubble. To fit the experimental data of previous studies, we assume that the ionization energies of the molecules and atoms in the bubble decrease as the gas density increases and that the decrease of the ionization energy reaches about 60%–70% as the bubble flashes, which is difficult to explain by using previous models. Project supported by the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20120002110031) and the National Natural Science Foundation of China (Grant No. 11334005).

  1. Glow-to-arc transition in plasma-assisted combustion at 100 MPa

    NASA Astrophysics Data System (ADS)

    Larsson, A.; Andreasson, S.

    2015-04-01

    Electric energy can be added to the combustion of solid propellants in a gun in order to augment and to control parts of the internal ballistic cycle of the launch of a projectile. The pressure in the chamber and bore during launch is typically several hundred megapascal and the electric energy must be delivered to the flame at such a pressure level. To increase the understanding of the interaction between a flame and an electrical discharge at elevated pressure, experiments have been performed at 100 MPa in a combustion chamber where electric current has been conducted through the flame of a solid propellant. Pressure, voltage and current have been measured. The measured signals have been analysed and interpreted. The sequence of events has been interpreted as an initial formation of a glow-like discharge in the flame followed by a discharge mode transition to a filamentary arc discharge. The transition is shown to be dependent on the flame conductivity. For the test propellant used (Nzk5230 doped with 5% potassium nitrate), the flame conductivity is calculated to be 0.84 S m?1 and the discharge mode transition is found to occur after a dissipation of 0.2–0.4 kJ, or 11–22 kJ m?1 of electric energy, at an electric power of 0.1–0.5 MW.

  2. A Rare Stapes Abnormality

    PubMed Central

    Kanona, Hala; Virk, Jagdeep Singh; Kumar, Gaurav; Chawda, Sanjiv; Khalil, Sherif

    2015-01-01

    The aim of this study is to increase awareness of rare presentations, diagnostic difficulties alongside management of conductive hearing loss and ossicular abnormalities. We report the case of a 13-year-old female reporting progressive left-sided hearing loss and high resolution computed tomography was initially reported as normal. Exploratory tympanotomy revealed an absent stapedius tendon and lack of connection between the stapes superstructure and footplate. The footplate was fixed. Stapedotomy and stapes prosthesis insertion resulted in closure of the air-bone gap by 50?dB. A review of world literature was performed using MedLine. Middle ear ossicular discontinuity can result in significant conductive hearing loss. This can be managed effectively with surgery to help restore hearing. However, some patients may not be suitable or decline surgical intervention and can be managed safely conservatively. PMID:25628909

  3. The abnormal fontanel.

    PubMed

    Kiesler, Joseph; Ricer, Rick

    2003-06-15

    The diagnosis of an abnormal fontanel requires an understanding of the wide variation of normal. At birth, an infant has six fontanels. The anterior fontanel is the largest and most important for clinical evaluation. The average size of the anterior fontanel is 2.1 cm, and the median time of closure is 13.8 months. The most common causes of a large anterior fontanel or delayed fontanel closure are achondroplasia, hypothyroidism, Down syndrome, increased intracranial pressure, and rickets. A bulging anterior fontanel can be a result of increased intracranial pressure or intracranial and extracranial tumors, and a sunken fontanel usually is a sign of dehydration. A physical examination helps the physician determine which imaging modality, such as plain films, ultrasonography, computed tomographic scan, or magnetic resonance imaging, to use for diagnosis. PMID:12825844

  4. The Hollow-Cathode Effect and the Theory of Glow Discharges

    Microsoft Academic Search

    P. F. Little; A. von Engel

    1954-01-01

    The nature of the processes in the cathode dark space and the negative glow of a glow discharge is not well understood. Moreover, the existing theory leading to relations between the cathode fall in potential, the current density, the width of the dark space and the electric field distribution in it is based on dubious assumptions and does not indicate

  5. Measuring the gas temperature in a glow discharge in nitrogen with rapid pumping

    Microsoft Academic Search

    V. V. Azharonok; V. V. Mel'nikov; D. K. Skutov; I. I. Filatova; N. I. Chubrik; V. D. Shimanovich

    1987-01-01

    Bands of the sequence &V = --2, --3, --4 of the second positive system of nitrogen N~(2+) were used in the capacity of the pyrometric component when studying glow discharge in sealed or weakly permeable tubes [6, 7]. The present work examines the usefulness of MURS for operational monitoring of the gas temperature in a glow discharge in an atmosphere

  6. A novel approach to resonance ionization mass spectrometry employing a glow discharge atom source

    Microsoft Academic Search

    X. Xiong; J. M. R. Hutchinson; K. R. Hess; J. D. Fassett; T. B. Lucatorto

    1996-01-01

    This paper reports on preliminary efforts to design and implement a novel combination of a laser, a glow discharge atom source, and a magnetic sector mass spectrometer to be used for resonance ionization of the discharge sputtered material. In this experimental design, a glow discharge source has been constructed and interfaced to a magnetic sector mass spectrometer. The laser is

  7. Characteristics of supersonic mixing CO2 laser combined with N2 axial glow discharge

    Microsoft Academic Search

    K. Maeno; A. Sakashita; Y. Hanaoka; K. Shimizu

    1989-01-01

    This paper deals with experimental and analytical investigation on supersonic CO2 mixing laser with N2 axial glow discharge. Measurements of small signal gain coefficient and laser power are conducted by the setup of cluster of glass channels for supersonic N2 glow discharge and CO2 conical screen nozzles. The discharge characteristics are also monitored. Supersonic flow of population inversion is maintained

  8. Gas temperature measurements in weakly ionized glow discharges with filtered Rayleigh scattering

    E-print Network

    Miles, Richard

    Gas temperature measurements in weakly ionized glow discharges with filtered Rayleigh scattering background. We perform measurements in weakly ionized glow discharges in pure argon and in an argon-plus-1:sapphire laser is used as the illumination source, and a mercury filter provides strong suppression of elastic

  9. The National Institute of Standards and Technology glow discharge resonance ionization mass spectrometry system

    Microsoft Academic Search

    L. Pibida; J. M. R. Hutchinson; Jesse Wen; L. Karam

    2000-01-01

    A new resonance ionization mass spectrometry system at the National Institute of Standards and Technology using glow discharge atomization and continuous-wave lasers has been developed. Low concentrations of 133Cs in a silver matrix have been measured using this new system. In addition a detailed characterization of the glow discharge source and laser ionization processes are made.

  10. Active Noise Control Using Glow Discharge Plasma Panels Christopher Ali Merchant

    E-print Network

    Active Noise Control Using Glow Discharge Plasma Panels by Christopher Ali Merchant B in partial fulfillment of the requirements for a degree of MASTER OF SCIENCE At the MASSACHUSETTS INSTITUTE Using Glow Discharge Plasma Panels by Christopher Ali Merchant Submitted to the Department

  11. Influence of the Walls on the Formation of a DC Glow Discharge

    Microsoft Academic Search

    Vladimir Demidov; Yevgeny Bogdanov; Steve Adams; Anatoly Kudryavtsev

    2009-01-01

    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

  12. Electric field reversal in near-cathode region of glow discharge in helium

    Microsoft Academic Search

    A. A. Kudryavtsev; S. U. Nisimov; E. I. Prokhorova; A. G. Slyshov

    2011-01-01

    Longitudinal distributions of plasma parameters in a short (free of positive column) glow discharge in helium show evidence for the formation of a potential well for thermal electrons and the reversal of electric field in plasma of negative glow and Faraday dark space. Depending on the reduced discharge length pL, one or two points of field reversal can appear, which

  13. Theory and Experiments Relating to the Striated Glow Discharge in Mercury Vapor

    Microsoft Academic Search

    K. T. Compton; Louis A. Turner; W. H. McCurdy

    1924-01-01

    Theory of the glow discharge in a monatomic gas.-For the case of parallel plane electrodes with a hot cathode as source of electrons, the potential distribution and ion concentration in the Crookes dark space, negative glow, Faraday dark space and positive column are shown to be predictable from considerations of space charge and of ionization and excitation of the gas.

  14. Longitudinal structure of capacitative radiofrequency gamma discharge and its analogy with a direct current glow discharge

    Microsoft Academic Search

    Yu P. Raizer; M. N. Shneider

    1994-01-01

    The longitudinal structure of a gamma -type RF discharge is computed and shown to have much in common with the structure of a direct current glow discharge. In a sufficiently long gap or at rather high pressures, there are regions of cathode fall, negative glow and Faraday dark space near each of the electrodes. A uniform positive column exists between

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

    Microsoft Academic Search

    E. A. Bogdanov; S. F. Adams; V. I. Demidov; A. A. Kudryavtsev; J. M. Williamson

    2010-01-01

    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

  16. The negative glow and Faraday dark space in near-normal neon discharges†

    Microsoft Academic Search

    G. A. WOOLSEY; R. M. REYNOLDS; W. B. MONTGOMERY; K. G. EMELEUS

    1969-01-01

    Radial and axial electrostatic probe measurements have been made of the negative glow and Faraday dark space of some weakly ‘ anomalous ’ cold cathode discharges in neon at pressures near 1 torr. These have been analysed and discussed with the aim of extending previous diffusion theories. Either an anode glow or positive column was present. The axial plasma electron

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

    Microsoft Academic Search

    E. A. Bogdanov; S. F. Adams; V. I. Demidov; A. A. Kudryavtsev; J. M. Williamson

    2010-01-01

    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

  18. Comparative Study of Plasma Anodization of Silicon in a Column of a dc Glow Discharge

    Microsoft Academic Search

    M. A. Copeland; R. Pappu

    1971-01-01

    A comparative study of plasma anodization of silicon in the column of a dc oxygen glow discharge is presented. Quantitative results for growth rates of silicon dioxide in the negative glow, Faraday dark space, positive column, and the anode fall are given. It is observed that the growth rate is higher in the positive column than the other regions of

  19. Note on Secondary Electrons in the Negative Glow and Faraday Dark Space

    Microsoft Academic Search

    H. M. GRTMLEY; K. G. EMELEUS

    1967-01-01

    Measurements have been made of the energy distributions of secondary electrons in the negative glow and Faraday dark space in helium, neon and air, using the double differential method with an unscreened and, in a few instances, a screened probe. The results are consistent with the supposition that the secondary electrons are produced in the negative glow and neigh-bouring parts

  20. Spark-to-glow discharge transition due to increased surface conductivity on epoxy resin specimens

    Microsoft Academic Search

    C. Hudon; R. Bartnikas; M. R. Wertheimer

    1993-01-01

    The effects of long exposure of epoxy resin surfaces to partial discharges under AC field stress were examined. The use of electrical pulse measuring techniques in conjunction with light emission measurements using a photomultiplier tube, which allowed simultaneous detection of both spark and glow discharges, permitted the establishment of a definite transition from spark to glow discharges. Spark discharges were

  1. Multijet atmospheric glow plasma cleaning of ablation debris from micro-via drilling process

    Microsoft Academic Search

    Eung Suok Lee; Hae Il Park; Hong Koo Baik; Se-Jong Lee; Kie Moon Song; Myung Keun Hwang; Chang Su Huh

    2002-01-01

    We devised a multi-jet atmospheric glow plasma system and successfully verified a possibility to ignite and maintain an atmospheric pressure discharge using helium, argon or a mixture of helium and oxygen gas. In this study, as an alternative method to the conventional wet cleaning process, the multi-jet atmospheric glow plasma system was applied to clean the ablation debris inside the

  2. Assessing the Warm Glow Effect in Contingent Valuations for Public Libraries

    ERIC Educational Resources Information Center

    Lee, Soon-Jae; Chung, Hye-Kyung; Jung, Eun-Joo

    2010-01-01

    This article aims to present evidence of the warm glow effect in a public library setting. More specifically, it tests whether individual respondents with different values for the warm glow component report different values for their willingness to pay (WTP). The data come from a contingent valuation survey conducted on randomly selected citizens…

  3. Role of photons in the glow discharge in hollow cylindrical cathodes

    Microsoft Academic Search

    R. M. CHAUDHRI; M. M. CHAUDHRI; F. DEBA; M. N. CHAUDHRI

    1987-01-01

    Experimental evidence has been provided to show that UV radiation produced in the discharge plays a predominant role in a self-maintained glow discharge in hollow cylindrical cathodes. It is shown that a glow discharge current flows in a hollow cylindrical cathode at a voltage much lower than its breakdown value if UV photons from a similar source, running under similar

  4. Peculiarities of metal surface glow under YAG:Nd laser pulses

    Microsoft Academic Search

    Alexander F. Banishev; Vladislav Y. Panchenko; Alexei V. Shishkov

    1999-01-01

    The paper deals with the study of laser-induced rising of defects onto the surface and W surface destruction. The non- thermal glow from the back, relative to the acting laser pulses, side of the sample was registered. The glow may be caused by defects rising onto the surface under considerable thermo elastic stresses in the laser effect ares.

  5. Glow experiment documentation of OMS/RCS pods and vertical stabilizer

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Glow experiment documentation of orbital maneuvering system (OMS) reaction control system (RCS) pods and vertical stabilizer shows chemoluminescent effect resulting from atomic oxygen impacting the spacecraft and building to the point that the atomic oxygen atoms combine to form molecules of oxygen. Image intensifier on NIKON 35mm camera used to record glow on vertical tail and OMS pods.

  6. Glow experiment documentation of OMS/RCS pods and vertical stabilizer

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Glow experiment documentation of orbital maneuvering system (OMS) reaction control system (RCS) pods and vertical stabilizer shows chemo-luminescent effect resulting from atomic oxygen impacting the spacecraft and building to the point that the atomic oxygen atoms combine to form molecules of oxygen. Image intensifier on NIKON 35mm camera was used to record glow on vertical tail and OMS pods.

  7. Glow experiment documentation of OMS/RCS pod and vertical stabilizer

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Glow experiment documentation of one of the orbital maneuvering system (OMS) reaction control system (RCS) pods and a portion of the vertical stabilizer shows chemoluminescent effectresulting from atomic oxygen impacting the spacecraft and building to the point that the atomic oxygen atoms combine to form molecules of oxygen. The Image Intensifier on NIKON 35mm camera was used to record the glow.

  8. Radial Distributions of Dusty Plasma Parameters in a Glow Discharge

    SciTech Connect

    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

    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.

  9. Glow Discharge Plasma Nitriding of AISI 304 Stainless Steel

    NASA Astrophysics Data System (ADS)

    Qayyum, A.; Naveed, M. A.; Zeb, S.; Murtaza, G.; Zakaullah, M.

    2007-08-01

    Glow discharge plasma nitriding of AISI 304 austenitic stainless steel has been carried out for different processing time under optimum discharge conditions established by spectroscopic analysis. The treated samples were analysed by X-ray diffraction (XRD) to explore the changes induced in the crystallographic structure. The XRD pattern confirmed the formation of an expanded austenite phase (?N) owing to incorporation of nitrogen as an interstitial solid solution in the iron lattice. A Vickers microhardness tester was used to evaluate the surface hardness as a function of indentation depth (?m). The results showed clear evidence of surface changes with substantial increase in surface hardness.

  10. Glow discharge assisted oxynitriding process of titanium for medical application

    NASA Astrophysics Data System (ADS)

    Wierzcho?, Tadeusz; Czarnowska, El?bieta; Grzonka, Justyna; Sowi?ska, Agnieszka; Tarnowski, Micha?; Kami?ski, Janusz; Kulikowski, Krzysztof; Borowski, Tomasz; Kurzyd?owski, Krzysztof J.

    2015-04-01

    The plasma oxynitriding process is a prospective method of producing titanium oxides as an integral part of a diffusive nitrided surface layer on titanium implants. This hybrid process, which combines glow discharge assisted nitriding and oxidizing, permits producing TiO2 + Ti2N + ?Ti(N)-type diffusive surface layers. The oxynitrided surface layers improve the corrosion and wear resistance of the substrate material. Additionally, the nanocrystalline titanium oxide TiO2 (rutile) improves the biological properties of titanium and its alloys when in contact with blood, whereas the TiN + Ti2N + ?Ti(N) zone eliminates the effect of metalosis.

  11. Nuclear product ratio for glow discharge in deuterium

    NASA Astrophysics Data System (ADS)

    Karabut, A. B.; Kucherov, Ya. R.; Savvatimova, I. B.

    1992-11-01

    New results for glow discharge in deuterium calorimetry are presented. In separate experiments a heat output five times exceeding the input electric power was observed. The result for the charged particle spectrum measurement is presented. Charged particles with energies up to 18 MeV and an average energy of 2-4 MeV were seen. Beams of gamma-rays with energies of about 200 keV and a characteristic X-ray radiation were registered. The summed energy of the registered products is three orders short of the values needed to explain the calorimetric results.

  12. Diode laser excited optogalvanic spectroscopy of glow discharges

    SciTech Connect

    Barshick, C. M.; Shaw, R. W.; Jennings, L. W.; Post-Zwicker, A.; Young, J. P.; Ramsey, J. M. [Chemical and Analytical Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tenessee 37831-6142 (United States)

    1997-01-15

    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 {sup 235}U/({sup 235}U+{sup 238}U) isotope ratios in these samples. The precision and accuracy of this determination is evaluated, and a study of experimental parameters pertaining to optimization of the measurement is discussed. Application of GD-OGS to other f-transition elements is also described.

  13. Diode laser excited optogalvanic spectroscopy of glow discharges

    SciTech Connect

    Barshick, C.M.; Shaw, R.W.; Jennings, L.W.; Post-Zwicker, A.; Young, J.P.; Ramsey, J.M. [Chemical Analytical Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tenessee 37831-6142 (United States)

    1997-01-01

    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 {sup 235}U/({sup 235}U+{sup 238}U) isotope ratios in these samples. The precision and accuracy of this determination is evaluated, and a study of experimental parameters pertaining to optimization of the measurement is discussed. Application of GD-OGS to other f-transition elements is also described. {copyright} {ital 1997 American Institute of Physics.}

  14. Diode laser excited optogalvanic spectroscopy of glow discharges

    SciTech Connect

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

    1996-10-01

    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.

  15. Study of N2/He DC glow discharge

    NASA Astrophysics Data System (ADS)

    Villa, M.; Flores, O.; Castillo, F.; Reyes, P. G.; Martinez, H.

    2015-03-01

    Optical emission spectroscopy and mass spectrometry measurement were used to study a gas mixture glow discharge of He and N2 at total pressure of 2.0 Torr, a power of 10 W and a flow of 16.5 l/min. The emission bands were measured in the wavelength range of 200 to 1100 nm. The principal species observed were N2+ (B2?+u?X2?+g), N2 (C3?u?B3?g), and He, which agree with mass spectrometry measurement.

  16. Electrical and optical characterization of CO2/He glow discharge

    NASA Astrophysics Data System (ADS)

    Reyes, P. G.; Torres, C.; Torres, J.; Gómez, A.; Martínez, H.; Vergara, J.

    2015-03-01

    Glow discharge studies are produced in a atmosphere of CO2/He mixture at a pressure of 1.5 Torr . The experiment was conducted to observe the optical emission spectroscopy of the plasma, and determined the electron temperature and ion density by the use of a double Langmuir probe. The electron temperature of the mixture was found in the range of 4.54 to 5.37 eV, and the ion density values between 2.15 and 12.00 × 109 particles/cm3. The principal species observed were: CO2+ CO+, CO, C2, O2+ O*, and He*.

  17. LANL Transfers Glowing Bio Technology to Sandia Biotech

    ScienceCinema

    Rorick, Kevin

    2012-08-02

    Partnering with Los Alamos National Laboratory, an Albuquerque-based company is seeking to transform the way protein and peptide analysis is conducted around the world. Sandia Biotech is using a biological technology licensed from Los Alamos called split green fluorescent protein (sGFP), as a detecting and tracking tool for the protein and peptide industry, valuable in the fields of Alzheimer's research, drug development and other biotechnology fields using protein folding to understand protein expression and mechanisms of action. http://www.lanl.gov/news/stories/glowing-future-for-los-alamos-and-sandia-b iotech-partnership.html

  18. Characteristics of short dc glow microdischarges in atmospheric pressure air

    NASA Astrophysics Data System (ADS)

    Kudryavtsev, Anatoly

    2013-09-01

    The main reason that high pressure current-carrying plasmas tend to be unstable is various instability (primarily thermal) of the positive column (PC). So a promising approach is to use short (without PC) discharges that have growing voltage-current characteristic (VAC). These discharges are ignited near the minimum of the Paschen breakdown curve Lmin and it usually have a gap pL <10-20 cm Torr when a distinct PC is absent. In this report the most stable microdischarges were burning with a flat cathode and rounded (or thin rod) anode, which located to a distance less than Lmin when the microdischarge ``choose'' their length itself, so that to match the stable work near Lmin by changing their binding on the anode. For simulations we used 2D hybrid model. Simulations predicted the main regions of the dc glow discharges including cathode and anode sheath and plasma of negative glow, Faraday dark space and transition region, in which the electric field is distributed no uniformly and plasma is nonlocal. Gas heating plays an important role in shaping the discharge profiles. The main reason that high pressure current-carrying plasmas tend to be unstable is various instability (primarily thermal) of the positive column (PC). So a promising approach is to use short (without PC) discharges that have growing voltage-current characteristic (VAC). These discharges are ignited near the minimum of the Paschen breakdown curve Lmin and it usually have a gap pL <10-20 cm Torr when a distinct PC is absent. In this report the most stable microdischarges were burning with a flat cathode and rounded (or thin rod) anode, which located to a distance less than Lmin when the microdischarge ``choose'' their length itself, so that to match the stable work near Lmin by changing their binding on the anode. For simulations we used 2D hybrid model. Simulations predicted the main regions of the dc glow discharges including cathode and anode sheath and plasma of negative glow, Faraday dark space and transition region, in which the electric field is distributed no uniformly and plasma is nonlocal. Gas heating plays an important role in shaping the discharge profiles. Work supported by FZP and SPbSU.

  19. Clinical potential of the side-glowing optical fibers

    NASA Astrophysics Data System (ADS)

    Spigulis, Janis; Pfafrods, Daumants

    1997-04-01

    Unconventional designs of silica-core optical fibers providing efficient lateral emission through the cylindrical side surface have been developed and manufactured. A physical model of the side-glowing fibers, available experimental data and potential clinical applications of this type of lightguides are discussed. Promising, clinical applications can be expected in the following areas: (1) Phototherapy, including photo-dynamic therapy, soft-laser therapy and visible/UV broadband irradiation therapy. (2) Single-fiber laser Doppler flowmetry. (3) Laser-tissue dosimetry. (4) Linear and planar 'cold light' illumination. (5) Optical sensing of mechanical pressure.

  20. Atomic emission and laser excited atomic fluorescence studies of the glow discharge for the analysis of microsamples

    SciTech Connect

    Becerra Marmolejo, E.

    1992-01-01

    The glow discharge as an atomizer for atomic spectroscopy offers excellent advantages that have not been fully exploited. In this work fundamental studies about the sputtering process of liquid microsamples was investigated. This work was done by two different approaches: Atomic Emission Spectroscopy using a wavelength modulation technique for simultaneous background correction, and Laser Excited Atomic Fluorescence Spectroscopy. In the first approach, the sample holder was a cooled cooper hollow electrode. The hollow depth as well as the atomizer operating parameters -- current, voltage, and pressure -- were optimized in order to follow the temporal behavior of the analyte. In the second approach, the sample holder was a hot planar copper electrode. Here, the atomic excitation process was produced by a copper vapor pumped dye laser at a repetition rate of 6,000 Hz, and the fluorescence signal was collected at 90 degrees from the laser path. In the atomic fluorescence studies a comparison of the pulsed and non-pulsed operating modes of the glow discharge was carried out. Also, information about the vertical atomic distribution in the chamber area was obtained. Calibration curves and figures of merit for lead and gallium using the atomic emission system and lead using the atomic fluorescence system were determined. The effect of sodium chloride as a matrix interferant was investigated using both techniques. The results of these studies using the two approaches along with brief discussions about their theoretical aspects are presented in this dissertation.

  1. Properties of the positive column of a glow discharge in flowing hydrogen H. Brunet, J. Rocca Serra and M. Mabru

    E-print Network

    Paris-Sud XI, Université de

    1525 Properties of the positive column of a glow discharge in flowing hydrogen H. Brunet, J. Rocca of the positive column in a glow discharge are presented. A cylindrical discharge at low pressure (~ 30 torr in'a large class of molecular and chemical lasers. Numerous investigations of properties of a glow

  2. Experimental study of a low-pressure glow discharge in air in large-diameter discharge tubes: I. conditions for the normal regime of a glow discharge

    Microsoft Academic Search

    V. A. Lisovskiy; S. D. Yakovin

    2000-01-01

    The initiation and characteristics of a low-pressure glow discharge in air in large-diameter discharge tubes are studied.\\u000a A deviation from the Paschen law is observed: the breakdown curves U\\u000a dc(pL) shift toward the higher values of U\\u000a dc and pL as the interelectrode distance L increases. It is shown that the normal regime of a glow discharge is accompanied by

  3. Deconvolution and simulation of thermoluminescence glow curves with Mathcad.

    PubMed

    Kiisk, V

    2013-09-01

    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

  4. Ozone generation using atmospheric pressure glow discharge in air

    NASA Astrophysics Data System (ADS)

    Buntat, Z.; Smith, I. R.; Razali, N. A. M.

    2009-12-01

    This paper presents results from a study into the generation of ozone by a stable atmospheric glow discharge, using dry air as the feeding gas for ozone generation. The power supply is 50 Hz ac, with the use of a perforated aluminium sheet for the electrodes and soda lime glass as a dielectric layer in a parallel-plate configuration, stabilizing the generation process and enabling ozone to be produced. The stable glow discharge spreads uniformly at a gas breakdown voltage below 4.8 kV and requires only 330 mW discharge power, with a limitation of 3 mm on the maximum gap spacing for the dry air. With the technique providing a high collision rate between the electrons and gas molecules during the discharge process, a high ozone yield is obtained. An analysis of the effect on the production rate of parameters such as the input voltage, gas flow rate and reaction chamber dimensions resulted in a highest efficiency of production of almost 350 g kWh-1 and confirms its potential as an important ozone generation technology.

  5. On electron bunching and stratification of glow discharges

    NASA Astrophysics Data System (ADS)

    Golubovskii, Yuri B.; Kolobov, Vladimir I.; Nekuchaev, Vladimir O.

    2013-10-01

    Plasma stratification and excitation of ionization waves is one of the fundamental problems in gas discharge physics. Significant progress in this field is associated with the name of Lev Tsendin. He advocated the need for the kinetic approach to this problem contrary to the traditional hydrodynamic approach, introduced the idea of electron bunching in spatially periodic electric fields, and developed a theory of kinetic resonances for analysis of moving striations in rare gases. The present paper shows how Tsendin's ideas have been further developed and applied for understanding the nature of the well-known S-, P-, and R-striations observed in glow discharges of inert gases at low pressures and currents. We review numerical solutions of a Fokker-Planck kinetic equation in spatially periodic electric fields under the effects of elastic and inelastic collisions of electrons with atoms. We illustrate the formation of kinetic resonances at specific field periods for different shapes of injected Electron Distribution Functions (EDF). Computer simulations illustrate how self-organization of the EDFs occurs under nonlocal conditions and how Gaussian-like peaks moving along resonance trajectories are formed in a certain range of discharge conditions. The calculated EDFs agree well with the experimentally measured EDFs for the S, P, and R striations in noble gases. We discuss how kinetic resonances affect dispersion characteristics of moving striations and mention some non-linear effects associated with glow discharge stratification. We propose further studies of stratification phenomena combining physical kinetics and non-linear physics.

  6. Intrinsic noise induced coherence resonance in a glow discharge plasma

    NASA Astrophysics Data System (ADS)

    Shaw, Pankaj Kumar; Saha, Debajyoti; Ghosh, Sabuj; Janaki, M. S.; Iyengar, A. N. Sekar

    2015-04-01

    Experimental evidence of intrinsic noise induced coherence resonance in a glow discharge plasma is being reported. Initially the system is started at a discharge voltage (DV) where it exhibited fixed point dynamics, and then with the subsequent increase in the DV spikes were excited which were few in number and with further increase of DV the number of spikes as well as their regularity increased. The regularity in the interspike interval of the spikes is estimated using normalized variance. Coherence resonance was determined using normalized variance curve and also corroborated by Hurst exponent and power spectrum plots. We show that the regularity of the excitable spikes in the floating potential fluctuation increases with the increase in the DV, up to a particular value of DV. Using a Wiener filter, we separated the noise component which was observed to increase with DV and hence conjectured that noise can play an important role in the generation of the coherence resonance. From an anharmonic oscillator equation describing ion acoustic oscillations, we have been able to obtain a FitzHugh-Nagumo like model which has been used to understand the excitable dynamics of glow discharge plasma in the presence of noise. The numerical results agree quite well with the experimental results.

  7. Hollow cathode glow discharge ring laser angular rate sensor

    SciTech Connect

    Lind, B.J.; Oskam, H.J.

    1989-04-11

    A ring laser is described, comprising: a gas impervious block containing at least three tunnels meeting to form a closed-loop gas containing cavity; electromagnetic wave reflecting surfaces, forming, in part, the cavity, for reflecting a pair of counter-propagating laser beams to propagate along the closed-loop cavity substantially defined by the tunnels; a gas contained within the closed-loop cavity; the tubular cavity having an electrically conductive surface to provide a first electrode adapted to be electrically connected to a negative supply voltage, a second electrode fixed to the block, adapted to be electrically connected to a positive supply voltage relative to the negative supply voltage; and the first and second electrodes positioned relative to each other to support a discharge current through the gas and establish a glow discharge region therebetween to induce a pair of counter-propagating laser beams to propagate through the glow discharge region in a direction transverse to the direction of the discharge current.

  8. The nature of magnetically stabilized direct current glow discharge

    SciTech Connect

    Dan`shchikov, E.V.; Masyukov, I.V. [Troitsk Institute for Innovation and Fusion Research, Moscow (Russian Federation)

    1995-12-31

    During the last several years magnetic stabilization technique has been used to high power CO{sub 2} laser discharge in order to prevent it from transition into contracted state, in addition to such stabilizing factors as additional ionization, distributive ballasting, fast blowing and convective cooling of the gas. Magnetic field enhances specific energy input to the uniform diffusive DC glow discharge plasma. However, the mechanism of magnetic stabilization was disguised by complexity of the discharge schemes. Recently, simple approaches were developed by applying magnetic field to slab direct current (DC) glow discharges with diffusive cooling of the gas, such as {open_quotes}Macken discharge{close_quotes} and {open_quotes}attached discharge{close_quotes}. The aim of the present paper is to gain insight into the nature of the magnetic stabilization on the basis of comparative analysis of these approaches using new experimental data. In experiments we used discharge camera formed from two dielectrically coated metal plates served as elements of magnetic system at the same time. Slab gap h between plates was 8 mm. Magnetic field strength B was varied up to 0.15 T. We adjusted electrode configuration to the type of discharge investigated.

  9. Characteristics of DC and pulsed hollow cathode glow discharge

    SciTech Connect

    Atta Khedr, M. [Old Dominion Univ., Norfolk, VA (United States). Physical Electronics Research Inst.; Hefny, A.A.; Hamdy, H.; Shahen, F. [Cairo Univ., Beni Suef (Egypt). Physics Dept.; Gamal, Y. [Cairo Univ., Giza (Egypt). National Inst. of Laser Enhanced Sciences

    1998-12-31

    The investigation of the characteristics of hollow cathode glow discharge and plasma produced are important in different applications, applied physics, technology, and environment, hollow cathode UV light sources, hollow cathode gas lasers, and air treatment. In this work the authors have studied the characteristics of two types of hollow cathode glow discharge and plasmas produced. One kind is plasma has a large area in low gas pressure (0.1 to 10 Torr) using three electrodes, the second is confined in a small area inside the two hollow electrodes under high gas pressure (20--400 Torr). The gases used were He, Ar and dry air. The results show that the current and voltage are dependent on the gas pressure. The lifetime of plasma is considered at value 300 {micro}s. The electron temperature and light intensity have an optimum value at threshold conditions of gas pressure. Increasing the gas pressure cause the plasma is exited due to the change of the gas conductivity, the plasma is confined in a small area at higher pressure and started to be off. The increasing of the gas molecules that is decreasing the mean free path of electrons and the thermal absorption increase.

  10. Interaction of a surface glow discharge with a gas flow

    SciTech Connect

    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

    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.

  11. Verification of the dual integral glow analysis dosimetry system

    NASA Astrophysics Data System (ADS)

    Wagner, Eric Christopher

    2000-10-01

    The Dual Integral Glow Analysis (DINGA) method is a unique approach to the determination of the low-LET dose deposited within a thermoluminescent personnel dosimeter. DINGA creates its estimate of the dose deposited by utilizing the integrals of a sub-section of the glow curves obtained from opposite sides of one or more thermoluminescent detectors (TLDs) and knowledge of the TLDs thermophysical parameters. The performance of DINGA is evaluated with computational simulations for a variety of heating methods and error tolerance is also examined by introducing errors into the inputs the DINGA code. It has been found that DINGA's dose estimates are off approximately, in the worst case, the same percentage as the input parameter was varied. Experimental measurements are performed using a hot-gas heating method for large personnel doses and a laser heating method for smaller personnel doses with LiF: Mg, Ti (TLD-100) dosimeters. The dosimeters are exposed to select radiation fields generated by either certified sources or fields characterized by certified equipment. The DINGA dosimetry system is found to correctly report shallow and deep dose well within the limits required for certification by the National Voluntary Accreditation Program. The worst performance quotient is 0.19, well below the strictest limit of 0.30.

  12. Haem degradation in abnormal haemoglobins.

    PubMed Central

    Brown, S B; Docherty, J C

    1978-01-01

    The coupled oxidation of certain abnormal haemoglobins leads to different bile-pigment isomer distributions from that of normal haemoglobin. The isomer pattern may be correlated with the structure of the abnormal haemoglobin in the neighbourhood of the haem pocket. This is support for haem degradation by an intramolecular reaction. PMID:708385

  13. Abnormal pressure in hydrocarbon environments

    USGS Publications Warehouse

    Law, B.E.; Spencer, C.W.

    1998-01-01

    Abnormal pressures, pressures above or below hydrostatic pressures, occur on all continents in a wide range of geological conditions. According to a survey of published literature on abnormal pressures, compaction disequilibrium and hydrocarbon generation are the two most commonly cited causes of abnormally high pressure in petroleum provinces. In young (Tertiary) deltaic sequences, compaction disequilibrium is the dominant cause of abnormal pressure. In older (pre-Tertiary) lithified rocks, hydrocarbon generation, aquathermal expansion, and tectonics are most often cited as the causes of abnormal pressure. The association of abnormal pressures with hydrocarbon accumulations is statistically significant. Within abnormally pressured reservoirs, empirical evidence indicates that the bulk of economically recoverable oil and gas occurs in reservoirs with pressure gradients less than 0.75 psi/ft (17.4 kPa/m) and there is very little production potential from reservoirs that exceed 0.85 psi/ft (19.6 kPa/m). Abnormally pressured rocks are also commonly associated with unconventional gas accumulations where the pressuring phase is gas of either a thermal or microbial origin. In underpressured, thermally mature rocks, the affected reservoirs have most often experienced a significant cooling history and probably evolved from an originally overpressured system.

  14. Modeling the breakdown and glow phases during ignition of HID lamps

    SciTech Connect

    Liland, K.B.; Peres, I.; Pitchford, L.C.; Boeuf, J.P. [Univ. Paul Sabatier, Toulouse (France)

    1996-12-31

    HID lamps are often ignited by one or more short, high voltage pulses (trigger pulses) superimposed on the low frequency, generator voltage. The authors have developed a self-consistent, fluid model of transient glow discharges to study the breakdown and glow phases in HID lamps from the time of the application of the trigger pulse(s) to the time when there is a fully-developed, quasi-steady state glow discharge. The transition to the thermionic arc is not considered here. Using this model they have investigated the influence of the height, width and number of trigger pulses on the generator voltage required to achieve a steady-state glow discharge. The model used is one-dimensional, and the fundamental variables are the charged particle densities and the potential as functions of distance between the electrodes and time. The minimum voltage needed to initiate a glow discharge, V{sub g}, decreases with increasing current during the trigger pulse and reaches a minimum which is a few volts above the steady-state glow voltage. Results in discharges in argon and argon/mercury mixtures will be presented showing the dependence of V{sub g} on the trigger pulse and on other discharge conditions (gas mixture, external circuit, ...). The calculated, steady-state glow current-voltage characteristic will also be presented.

  15. On copper diffusion in silicon measured by glow discharge mass spectrometry.

    PubMed

    Modanese, Chiara; Gaspar, Guilherme; Arnberg, Lars; Di Sabatino, Marisa

    2014-11-01

    Copper contamination occurs frequently in silicon for photovoltaic applications due to its very fast diffusion coupled with a low solid solubility, especially at room temperature. The combination of these properties exerts a challenge on the direct analysis of Cu bulk concentration in Si by sputtering techniques like glow discharge mass spectrometry (GDMS). This work aims at addressing the challenges in quantitative analysis of fast diffusing elements in Si matrix by GDMS. N-type, monocrystalline (Czochralski) silicon samples were intentionally contaminated with Cu after solidification and consequently annealed at 900 °C to ensure a homogeneous distribution of Cu in the bulk. The samples were quenched after annealing to control the extent of the diffusion to the surface prior to the GDMS analyses, which were carried out at different time intervals from within few minutes after cooling onward. The Cu profiles were measured by high-resolution GDMS operating in a continuous direct current mode, where the integration step length was set to ?0.5 ?m over a total sputtered depth of 8-30 ?m. The temperature of the samples during the GDMS analyses was also measured in order to evaluate the diffusion. The Cu contamination of n-type Si samples was observed to be highly material dependent. The practical impact of Cu out-diffusion on the calculation of the relative sensitivity factor (RSF) of Cu in Si is discussed. PMID:25146357

  16. Industrial applications of the one atmosphere uniform glow discharge plasma

    SciTech Connect

    Roth, J.R. [Univ. of Tennessee, Knoxville, TN (United States)

    1998-12-31

    Over the past six years, the author has developed at the UTK Plasma Sciences Laboratory a proprietary and patented technology for generating a One Atmosphere Uniform Glow Discharge Plasma (OAUGDP), and also for industrial plasma processing applications of this discharge. A OAUGDP in air efficiently generates plasma active species, including ozone and atomic oxygen, without the requirement of a vacuum system or batch processing. The OAUGDP operates in a frequency band determined by the ion trapping mechanism provided that, for air, the electric field is above about 8.5 kV/cm. For proper values of gap distance, RF driving frequency, and rms voltage, the OAUGDP produces a uniform plasma without avalanches, streamers, or filamentary microdischarges. In the OAUGDP, the plasma characteristics, including the electron energy and density, are functions of time. This time dependence has been studied experimentally and by computer modeling for an atmospheric helium plasma. The simulation clearly shows that at any given phase of the RF cycle, the instantaneous discharge between the electrodes has the classical characteristics of a DC normal glow discharge, including the negative glow, the Faraday dark space, the positive column, and the cathode region, in which the electric field and charge density obey Aston`s Law. The active species of the OAUGDP can be used to increase the surface energy of metals and polymers, to increase the wettability and wickability of polymeric fabrics and to sterilize and decontaminate surfaces compromised by infectious microbes and toxic chemicals. In addition, the OAUGDP can be operated in a wide range of geometrical configurations, from a slab plasma between parallel plates, to a surface plasma covering an isolated flat or curved surface, such as an airfoil. The surface OAUGDP can give rise to interesting and potentially important electrohydrodynamic (EHD) flow effects in the neutral background gas. This EHD flow acceleration can find application to aerodynamic boundary layer and flow control, pumping gases through tubes and ducts, and regulating the flow and uniformity of feed gases for atmospheric plasma processing.

  17. Chromosomal abnormalities in human sperm

    SciTech Connect

    Martin, R.H.

    1985-01-01

    The ability to analyze human sperm chromosome complements after penetration of zona pellucida-free hamster eggs provides the first opportunity to study the frequency and type of chromosomal abnormalities in human gametes. Two large-scale studies have provided information on normal men. We have studied 1,426 sperm complements from 45 normal men and found an abnormality rate of 8.9%. Brandriff et al. (5) found 8.1% abnormal complements in 909 sperm from 4 men. The distribution of numerical and structural abnormalities was markedly dissimilar in the 2 studies. The frequency of aneuploidy was 5% in our sample and only 1.6% in Brandriff's, perhaps reflecting individual variability among donors. The frequency of 24,YY sperm was low: 0/1,426 and 1/909. This suggests that the estimates of nondisjunction based on fluorescent Y body data (1% to 5%) are not accurate. We have also studied men at increased risk of sperm chromosomal abnormalities. The frequency of chromosomally unbalanced sperm in 6 men heterozygous for structural abnormalities varied dramatically: 77% for t11;22, 32% for t6;14, 19% for t5;18, 13% for t14;21, and 0% for inv 3 and 7. We have also studied 13 cancer patients before and after radiotherapy and demonstrated a significant dose-dependent increase of sperm chromosome abnormalities (numerical and structural) 36 months after radiation treatment.

  18. Electron yield of glow discharge cathode materials under helium ion bombardment

    NASA Astrophysics Data System (ADS)

    Szapiro, B.; Rocca, J. J.; Prabhuram, T.

    1988-08-01

    The secondary electron emission coefficient of materials for helium ion bombardment in the energy range 0.5-20 keV was measured for the surface conditions of cathodes in high voltage glow discharges. The materials studied are oxidized aluminum, oxidized magnesium, a molybdenum-aluminum oxide sintered composite, molybdenum, stainless steel, copper, gold, and graphite. Each sample was surface conditioned by operating it as cathode of a helium glow discharge shortly before the electron yield measurement. The results are relevant to the modeling of glow discharges and the design of cold cathode electron guns.

  19. Characterization of the glow-peak fading properties of six common thermoluminescent materials

    Microsoft Academic Search

    John A. Harvey; Nathan P. Haverland; Kimberlee J. Kearfott

    2010-01-01

    The pre-irradiation and post-irradiation fading rates of the thermoluminescent glow peaks of six commonly used thermoluminescent dosimeters under controlled environmental conditions over approximately 30d are examined. Glow peaks were fit to the first-order kinetics model using a computerized glow curve deconvolution program. Dosimeters studied were LiF:Mg,Ti, CaF2:Dy, CaF2:Tm, CaF2:Mn, LiF:Mg,Cu,P, and CaSO4:Dy. LiF:Mg,Ti and LiF:Mg,Cu,P experienced significant pre-irradiation fading. All

  20. Note: Rapid reduction of graphene oxide paper by glow discharge plasma.

    PubMed

    Bo, Zheng; Qian, Jiajing; Han, Zhao Jun; Duan, Liangping; Qiu, Kunzan; Ostrikov, Kostya Ken; Yan, Jianhua; Cen, Kefa

    2015-05-01

    This note reports on a novel method for the rapid reduction of graphene oxide (GO) paper using a glow discharge plasma reactor. Glow discharge is produced and sustained between two parallel-plate graphite electrodes at a pressure of 240 mTorr. By exposing GO paper at the junction of negative-glow and Faraday-dark area for 4 min, the oxygen-containing groups can be effectively removed (C/O ratio increases from 2.6 to 7.9), while the material integrality and flexibility are kept well. Electrochemical measurements demonstrate that the as-obtained reduced GO paper can be potentially used for supercapacitor application. PMID:26026562

  1. Determination of Actinide Isotope Ratios Using Glow Discharge Optogalvanic Spectroscopy

    SciTech Connect

    Young, J.P.; Shaw, R.W.; Barshick, C.M.; Ramsey, J.M.

    1997-08-01

    Diode-laser excited optogalvanic spectroscopy (OGS) of a glow discharge has been utilized to measure U-235/U-235 + U-238 isotope ratios. This ``optical mass spectrometric`` measurement has been demonstrated for a number of samples including uranium oxide, fluoride, and metal. Various diode-laser accessible atomic transitions in the 775 to 835 nm region have been evaluated; these transitions were chosen by considering OGS sensitivity and isotope shift. Using the 831.84 nm uranium line, for example, it was possible to measure the U-235/U-235 + U-238 isotope ratio (0.0026) of depleted uranium samples. A prototypical field instrument to make these measurements has been assembled and demonstrated. A U-236 spectral line was identified in a sample of enriched uranium, and an abundance sensitivity was measured.

  2. Hopf bifurcations in balance equations of glow discharges

    SciTech Connect

    Koch, B.; Goepp, N.; Bruhn, B. [Institut fuer Physik, Ernst-Moritz-Arndt-Universitaet Greifswald, Domstrasse 10a, 17487 Greifswald (Germany)] [Institut fuer Physik, Ernst-Moritz-Arndt-Universitaet Greifswald, Domstrasse 10a, 17487 Greifswald (Germany)

    1997-08-01

    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. {copyright} {ital 1997} {ital The American Physical Society}

  3. Mathematical description of a direct current glow discharge in argon.

    PubMed

    Bogaerts, A; Gijbels, R

    1996-07-01

    In order to achieve a better understanding of the glow discharge, different models have been developed for the different species present in the plasma. An overview of the models is given and some typical results are presented. These results include, among others, the densities and energy distributions of the plasma species, the electric field and potential distribution, the contribution of different ionization mechanisms to the ionization of argon and sputtered atoms, the relative contribution of different plasma species to the sputtering process, and the variation of the cathode dark space length and the electrical current as functions of voltage and pressure. The validity of the present models is supported by the good agreement of the calculated current-voltage curves with experiment. PMID:15045278

  4. Flush-mounted probe diagnostics for argon glow discharge plasma

    SciTech Connect

    Xu, Liang, E-mail: xld02345@mail.ustc.edu.cn; Cao, Jinxiang; Liu, Yu; Wang, Jian; Du, Yinchang; Zheng, Zhe; Zhang, Xiao; Wang, Pi [Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Zhang, Jin; Li, Xiao; Qin, Yongqiang; Zhao, Liang [Science and Technology on Space Physics Laboratory, Beijing 100076 (China)

    2014-09-15

    A comparison is made between plasma parameters measured by a flush-mounted probe (FP) and a cylindrical probe (CP) in argon glow discharge plasma. Parameters compared include the space potential, the plasma density, and the effective electron temperature. It is found that the ion density determined by the FP agrees well with the electron density determined by the CP in the quasi-neutral plasma to better than 10%. Moreover, the space potential and effective electron temperature calculated from electron energy distribution function measured by the FP is consistent with that measured by the CP over the operated discharge current and pressure ranges. These results present the FP can be used as a reliable diagnostic tool in the stable laboratory plasma and also be anticipated to be applied in other complicated plasmas, such as tokamaks, the region of boundary-layer, and so on.

  5. Glow discharge cleaning of carbon fiber composite and stainless steel

    NASA Astrophysics Data System (ADS)

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

    2011-08-01

    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.

  6. Fluorination of polymethylmethaacrylate with tetrafluoroethane using DC glow discharge plasma

    NASA Astrophysics Data System (ADS)

    Guruvenket, S.; Iyer, Ganjigunte R. S.; Shestakova, Larisa; Morgen, Per; Larsen, N. B.; Mohan Rao, G.

    2008-07-01

    Fluorination of polymer surfaces has technological applications in various fields such as microelectronics, biomaterials, textile, packing, etc. In this study PMMA surfaces were fluorinated using DC glow discharge plasma. Tetrafluoroethane was used as the fluorinating agent. On the fluorinated PMMA surface, static water contact angle, surface energy, optical transmittance (UV-vis), XPS and AFM analyses were carried out. After the fluorination PMMA surface becomes hydrophobic with water contact angle of 107° without losing optical transparency. Surface energy of fluorine plasma-treated PMMA decreased from 35 mJ/cm 2 to 21.2 mJ/cm 2. RMS roughness of the fluorinated surface was 4.01 nm and XPS studies revealed the formation of C-CF x and CF 3 groups on the PMMA surface.

  7. Measuring Anthropogenic Sky Glow Using a Natural Sky Brightness Model

    NASA Astrophysics Data System (ADS)

    Duriscoe, Dan M.

    2013-11-01

    Anthropogenic sky glow (a result of light pollution) combines with the natural background brightness of the night sky when viewed by an observer on the earth''s surface. In order to measure the anthropogenic component accurately, the natural component must be identified and subtracted. A model of the moonless natural sky brightness in the V-band was constructed from existing data on the Zodiacal Light, an airglow model based on the van Rhijn function, and a model of integrated starlight (including diffuse galactic light) constructed from images made with the same equipment used for sky brightness observations. The model also incorporates effective extinction by the atmosphere and is improved at high zenith angles (>80°) by the addition of atmospheric diffuse light. The model may be projected onto local horizon coordinates for a given observation at a resolution of 0.05° over the hemisphere of the sky, allowing it to be accurately registered with data images obtained from any site. Zodiacal Light and integrated starlight models compare favorably with observations from remote dark sky sites, matching within ± 8 nL over 95% of the sky. The natural airglow may be only approximately modeled, errors of up to ± 25 nL are seen when the airglow is rapidly changing or has considerable character (banding); ± 8 nL precision may be expected under favorable conditions. When subtracted from all-sky brightness data images, the model significantly improves estimates of sky glow from anthropogenic sources, especially at sites that experience slight to moderate light pollution.

  8. Trace elements in coal by glow discharge mass spectrometry

    SciTech Connect

    Jacobs, M.L.; Wilson, C.R.; Pestovich, J. Jr. [WAL Inc., Wheat Ridge, CO (United States)] [and others

    1995-08-01

    A need and a demand exist for determining trace elements in coal and coal related by-products, especially those elements which may potentially be a health hazard. The provisions of the 1990 clean air act require that the EPA evaluate the emissions of electric utilities for trace elements and other potentially hazardous organic compounds. The coal fired electric utility industry supplies roughly 60% of the total generating capacity of 2,882,525 million kilowatt hours (nearly 3 trillion kilowatt hours) generated in the U.S. This is accomplished by 414 power plants scattered across the country that burned 813,508,000 short tons of coal in 1993. The relative volatility of some inorganic constituents in coal makes them more prone to be emitted to the atmosphere following combustion. The production of analytical data for trace elements is known to be a difficult task in coal and by-products of coal combustion (fly ash, bottom ash, gas streams, etc.), in terms of both sample collection and analytical determinations. There are several common analytical methods available to the analyst to determine trace elements in coal and coal by-products. In general analytical germs, the material to be analyzed can be totally solubilized (or extracted), or the elements analytes can be determined in the material as a solid. A relatively new elemental technique, Glow Discharge Mass Spectrometry (GDMS) can be used with solids as well. This new analytical technique had never before been applied directly to coal. The radio frequency-glow discharge quadropole mass spectrometer was used to analyze coal directly for the first time ever by rf-GDMS. The rf-GDMS technique is described.

  9. Dust Waves Excited in a DC Glow Discharge Plasma

    SciTech Connect

    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

    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.

  10. Glow discharges with electrostatic confinement of fast electrons

    NASA Astrophysics Data System (ADS)

    Kolobov, V. I.; Metel, A. S.

    2015-06-01

    This review presents a unified treatment of glow discharges with electrostatic confinement of fast electrons. These discharges include hollow cathode discharges, wire and cage discharges, reflect discharges with brush and multirod cathodes, and discharges in crossed electric and magnetic fields. Fast electrons bouncing inside electrostatic traps provide efficient ionization of gas at very low gas pressures. The electrostatic trap effect (ETE) was first observed by Paschen in hollow cathode discharges almost a century ago. The key parameters that define fundamental characteristics of ETE discharges are the ionization length ?N, the penetration range, ?, and the diffusion length ? of the fast electrons, and two universal geometric parameters of the traps: effective width a and length L. Peculiarities of electron kinetics and ion collection mechanism explain experimental observations for different trap geometries. The ETE is observed only at ??>?a, when the penetration range of the ?-electrons emitted by the cathode exceeds the trap width. In the optimal pressure range, when ?N?>?a, and ???L, Uc rises from hundreds to thousands of volts. The sign of the anode potential fall, Ua, depends on the anode surface Sa and its position. When Sa is large compared to a critical value S*, Ua is negative and small. At Sa?glow discharges with electrostatic confinement of fast electrons are described.

  11. Emergency and Abnormal Situations Project

    E-print Network

    --------------------------------------------------------Context Dependent Manufacturers Regulatory Agencies Company (Management, Dispatch, Maintenance) Flight and Cabin Crews ATC #12;Economic and Regulatory Pressures Philosophies Emergency and Abnormal Situations Project Taxonomy of the Domain Economic and Regulatory Pressures Pertaining to Dealing with and Training

  12. Electron emission from glow-discharge cathode materials due to neon and argon ion bombardment

    NASA Astrophysics Data System (ADS)

    Szapiro, B.; Rocca, J. J.

    1989-05-01

    The electron yields of 7 glow-discharge cathode materials under bombardment by neon and argon ions with energies between 1 and 20 keV were measured. The surfaces of the samples were conditioned by operating the materials as cold cathodes in a high-voltage glow discharge before the electron yield measurement. The materials studied are oxidized magnesium, oxidized aluminum, a molybdenum-aluminum oxide sintered composite, molybdenum, stainless steel, copper, and graphite. The dependence of electron yield on ion velocity was found to be approximately linear for all materials and gases, with the slopes being strongly material dependent. The corresponding glow-discharge current intensities were observed to have a supralinear dependence on the electron yield. The results are relevant to the design and modeling of cold cathode high-voltage glow discharges.

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

    NASA Astrophysics Data System (ADS)

    Kitis, G.

    2011-05-01

    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, Al 2O 3: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 Al 2O 3:C is performed using newly developed analytical expressions describing a single TL peak obtained under an exponential heating scheme.

  14. Gain characteristics of CO/sub 2/ supersonic mixing laser with N2 axial glow discharge

    SciTech Connect

    Maeno, K.; Hanaoka, Y.; Hirose, M.

    1987-06-01

    An experimental and analytical study of a CO/sub 2/ supersonic mixing laser by N/sub 2/ axial glow discharge is presented. A cluster of supersonic and circular N/sub 2/ channels for axial glow discharge are employed to mix with CO/sub 2/ supersonic flow from conical screen nozzles. Small-signal gain measurement is conducted, together with monitoring discharge characteristics. Vibrationally nonequilibrium analysis of quasi-one-dimensional supersonic flow for the mixing laser is also presented, including N/sub 2/ collisional activation effects by electron impact in the glow discharge. Steady glow discharge in supersonic N/sub 2/ flow is obtained, and measured gain dependency on cavity flow distance, on plenum pressures, and on discharge power density in N/sub 2/ are discussed in comparison with numerically estimated characteristics. 11 references.

  15. How Things Work. Mystery Glow-Ball: When Is a Battery Not a Battery?

    ERIC Educational Resources Information Center

    Crane, H. Richard, Ed.

    1989-01-01

    Examines the working mechanism of a commercial "Mystery Glow-Ball" by analyzing its electronic circuitry. Finds that the advertising for the ball is wrong; energy actually came from inserting a battery. (YP)

  16. Glow discharge as an atomization and ionization device. Progress report, November 1, 1982-November 1, 1983

    SciTech Connect

    Harrison, W.W.

    1984-01-01

    Whether by direct resonant ionization or laser enhanced ionization, the result is a selective mass spectrum which features only isotopes of the selected element. The glow disharge offers possibilities for both resonance ionization mass spectroscopy and laser enhanced ionization with its various internal excitation possibilities. The combination of a tunable dye laser with the glow discharge can yield an advantageous method for the direct analysis of solids by mass spectrometry.

  17. Gain characteristics of CO2 supersonic mixing laser with N2 axial glow discharge

    Microsoft Academic Search

    K. Maeno; Y. Hanaoka; M. Hirose

    1987-01-01

    An experimental and analytical study of a CO2 supersonic mixing laser by N2 axial glow discharge is presented. A cluster of supersonic and circular N2 channels for axial glow discharge are employed to mix with CO2 supersonic flow from conical screen nozzles. Small-signal gain measurement is conducted, together with monitoring discharge characteristics. Vibrationally nonequilibrium analysis of quasi-one-dimensional supersonic flow for

  18. Rarefied hypersonic flow in a plane channel with a surface glow discharge

    Microsoft Academic Search

    S. T. Surzhikov

    2009-01-01

    The gasdynamic structure of a hypersonic molecular nitrogen flow in a plane channel whose opposite surfaces are segmented\\u000a electrodes for generating a continuous surface glow discharge is investigated using a two-dimensional computational model.\\u000a The electrodynamic structure of the surface glow discharge in the hypersonic rarefied gas flow (distributions of the charged\\u000a particle concentrations, current density, and electric potential) is studied.

  19. Radio-frequency glow discharge ion source for high resolution mass spectrometry

    Microsoft Academic Search

    A. I. Saprykin; F.-G. Melchers; J. S. Becker; H.-J. Dietze

    1995-01-01

    A radio-frequency powered glow discharge ion source has been developed for a double-focusing mass spectrometer. The sputtering and ionization of conducting, semiconducting and insulating materials have been realized using a 13.56 MHz generator to supply the discharge operating potential. The glow discharge ion source operates stably at argon pressures of 0.1–1 hPa and radio frequency powers of 10–50 W. The

  20. Electric field reversal in near-cathode region of glow discharge in helium

    NASA Astrophysics Data System (ADS)

    Kudryavtsev, A. A.; Nisimov, S. U.; Prokhorova, E. I.; Slyshov, A. G.

    2011-09-01

    Longitudinal distributions of plasma parameters in a short (free of positive column) glow discharge in helium show evidence for the formation of a potential well for thermal electrons and the reversal of electric field in plasma of negative glow and Faraday dark space. Depending on the reduced discharge length pL, one or two points of field reversal can appear, which determines the sign of the anode fall.

  1. Role of nonlocal ionization in formation of the short glow discharge

    Microsoft Academic Search

    A. A. Kudryavtsev; A. V. Morin; L. D. Tsendin

    2008-01-01

    An analytical model for estimating basic characteristics of short (without a positive column) glow discharges is suggested\\u000a that allows for electron generation both in the cathode sheath and by nonlocal ionization in the plasma negative glow. The\\u000a model is based on a previously developed approach according to which the discharge gap is divided into space-charge layers\\u000a and a quasi-neutral plasma.

  2. Kidney transplantation in abnormal bladder

    PubMed Central

    Mishra, Shashi K.; Muthu, V.; Rajapurkar, Mohan M.; Desai, Mahesh R.

    2007-01-01

    Structural urologic abnormalities resulting in dysfunctional lower urinary tract leading to end stage renal disease may constitute 15% patients in the adult population and up to 20-30% in the pediatric population. A patient with an abnormal bladder, who is approaching end stage renal disease, needs careful evaluation of the lower urinary tract to plan the most satisfactory technical approach to the transplant procedure. Past experience of different authors can give an insight into the management and outcome of these patients. This review revisits the current literature available on transplantation in abnormal bladder and summarizes the clinical approach towards handling this group of difficult transplant patients. We add on our experience as we discuss the various issues. The outcome of renal transplant in abnormal bladder is not adversely affected when done in a reconstructed bladder. Correct preoperative evaluation, certain technical modification during transplant and postoperative care is mandatory to avoid complications. Knowledge of the abnormal bladder should allow successful transplantation with good outcome. PMID:19718334

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

    SciTech Connect

    R. STEINER; D. WAYNE

    1998-12-01

    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.

  4. Assessment of Ge-doped optical fibres as a TSL-mode detector M. Benabdesselam*

    E-print Network

    Boyer, Edmond

    luminescence (TSL) or thermoluminescence glow curve between 300 and 773 K of germanium-doped silica optical and luminescence parameters Among various studied optical fibres, Ge-doped one and named GeD2 is by far, the mostAssessment of Ge-doped optical fibres as a TSL-mode detector M. Benabdesselam* , F. Mady* , S

  5. VUV-Emission from He-Xe-Glow Discharges

    NASA Astrophysics Data System (ADS)

    Lange, Hartmut; Uhrlandt, Dirk

    1999-10-01

    Discharge lamps with an emission in UV and VUV are used in many industrial applications as for instance UV oxidation of organic compounds, pollutions and UV synthesis of chemicals or as fluorescent lamps. A possible realization of such radiation-sources is the low-pressure-direct current discharge in Xe-He-mixtures with the resonance-radiation of xenon at 147 nm. Data to the radiation power of this resonance-radiation as well as their efficiency in the column plasma of low-pressure glow discharges are available only insufficiently. The absolute radiance of the 147 nm-resonance radiation has been studied as a function of the discharge parameters by means of the comparison with the radiance of a radiometric source standard. Simultaneously, the atom density of the lowest excited Xe-resonance level has been measured by means of laser-atom-absorption-spectroscopy. Thus a calculation of the absolute radiation power became possible. The experimental data are compared with the results of the theoretical description based on the solution of the electron kinetic equation and the balances of the excited states. Measured and calculated data of the radiation power agree well. The efficiency of the line radiation at 147 nm has been observed to increase with decreasing xenon pressure.

  6. Killing Microorganisms with the One Atmosphere Uniform Glow Discharge Plasma

    NASA Astrophysics Data System (ADS)

    South, Suzanne; Kelly-Wintenberg, Kimberly; Montie, T. C.; Reece Roth, J.; Sherman, Daniel; Morrison, Jim; Chen, Zhiyu; Karakaya, Fuat

    2000-10-01

    There is an urgent need for the development of new technologies for sterilization and decontamination in the fields of healthcare and industrial and food processing that are safe, cost-effective, broad-spectrum, and not deleterious to samples. One technology that meets these criteria is the One Atmosphere Uniform Glow Discharge Plasma (OAUGDP). The OAUGDP operates in air and produces uniform plasma without filamentary discharges at room temperature, making this technology advantageous for sterilization of heat sensitive materials. The OAUGDP operates in a frequency band determined by the ion trapping mechanisms provided that, for air, the electric field is above 8.5kV/cm. The OAUGDP efficiently generates plasma reactive oxygen species (ROS) including atomic oxygen and oxygen free radicals without the requirement of a vacuum system. We have demonstrated the efficacy of the OAUGDP in killing microorganisms including bacteria, yeast, viruses, and spores in seconds to minutes on a variety of surfaces such as glass, films and fabrics, stainless steel, paper, and agar.

  7. Use of Atmospheric Glow Discharge Plasma to Modify Spaceport Materials

    NASA Technical Reports Server (NTRS)

    Trigwell, S.; Shuerger, A. C.; Buhler, C. R.; Calle, C. J.

    2006-01-01

    Numerous materials used in spaceport operations require stringent evaluation before they can be utilized. It is critical for insulative polymeric materials that any surface charge be dissipated as rapidly as possible to avoid Electrostatic Discharges (ESD) that could present a danger. All materials must pass the Kennedy Space Center (KSC) standard electrostatic test [1]; however several materials that are considered favorable for Space Shuttle and International Space Station use have failed. Moreover, to minimize contamination of Mars spacecraft, spacecraft are assembled under cleanroom conditions and specific cleaning and sterilizing procedures are required for all materials. However, surface characteristics of these materials may allow microbes to survive by protecting them from sterilization and cleaning techniques. In this study, an Atmospheric Pressure Glow Discharge Plasma (APGD) [2] was used to modify the surface of several materials. This allowed the materials surface to be modified in terms of hydrophilicity, roughness, and conductivity without affecting the bulk properties. The objectives of this study were to alter the surface properties of polymers for improved electrostatic dissipation characteristics, and to determine whether the consequent surface modification on spaceport materials enhanced or diminished microbial survival.

  8. Neurophysiological model of the normal and abnormal human pupil

    NASA Technical Reports Server (NTRS)

    Krenz, W.; Robin, M.; Barez, S.; Stark, L.

    1985-01-01

    Anatomical, experimental, and computer simulation studies were used to determine the structure of the neurophysiological model of the pupil size control system. The computer simulation of this model demonstrates the role played by each of the elements in the neurological pathways influencing the size of the pupil. Simulations of the effect of drugs and common abnormalities in the system help to illustrate the workings of the pathways and processes involved. The simulation program allows the user to select pupil condition (normal or an abnormality), specific site along the neurological pathway (retina, hypothalamus, etc.) drug class input (barbiturate, narcotic, etc.), stimulus/response mode, display mode, stimulus type and input waveform, stimulus or background intensity and frequency, the input and output conditions, and the response at the neuroanatomical site. The model can be used as a teaching aid or as a tool for testing hypotheses regarding the system.

  9. Postural Abnormalities: An Individualized Program.

    ERIC Educational Resources Information Center

    Vodola, Thomas M.

    As one of the components of the Project ACTIVE (All Children Totally Involved Exercising) Teacher Training Model Kit, the manual is designed to enable the educator to organize, conduct, and evaluate individualized-personalized programs for children in grades 4 through 12 with postural abnormalities. An introductory chapter covers definitions and…

  10. [A boy with nail abnormalities].

    PubMed

    Atiq, Nasirah; van Meurs, Tim

    2013-01-01

    A 12-year-old boy consulted the dermatologist for nail abnormalities. Three weeks earlier, he was treated with doxycycline 100 mg BID for 10 days because of erythema chronicum migrans. Following sun exposure, the patient had developed distal onycholysis surrounded by a hyperpigmented zone. He was diagnosed with doxycycline-induced photo-onycholysis. PMID:23838405

  11. Steganography with Least Histogram Abnormality

    Microsoft Academic Search

    Xinpeng Zhang; Shuozhong Wang; Kaiwen Zhang

    2003-01-01

    A novel steganographic scheme is proposed which avoids asymmetry inherent in conventional LSB embedding techniques so that abnormality in the image histogram is kept minimum. The proposed technique is capable of re- sisting the ?2 test and RS analysis, as well as a new steganalytic method named GPC analysis as introduced in this paper. In the described steganographic tech- nique,

  12. Columnar discharge mode between parallel dielectric barrier electrodes in atmospheric pressure helium

    SciTech Connect

    Hao, Yanpeng; Zheng, Bin; Liu, Yaoge [School of Electric Power, South China University of Technology, Guangzhou 510640 (China)] [School of Electric Power, South China University of Technology, Guangzhou 510640 (China)

    2014-01-15

    Using a fast-gated intensified charge-coupled device, end- and side-view photographs were taken of columnar discharge between parallel dielectric barrier electrodes in atmospheric pressure helium. Based on three-dimensional images generated from end-view photographs, the number of discharge columns increased, whereas the diameter of each column decreased as the applied voltage was increased. Side-view photographs indicate that columnar discharges exhibited a mode transition ranging from Townsend to glow discharges generated by the same discharge physics as atmospheric pressure glow discharge.

  13. Thermally stimulated luminescence glow curve structure of ?-irradiated CaB4 O7 :Dy.

    PubMed

    Ak?n, Aycan; Ekdal, Elçin; Tuncer Arslanlar, Yasemin; Ayvac?kl?, Mehmet; Karal?, Turgay; Can, Nurdo?an

    2014-11-27

    Thermally stimulated luminescence glow curves of CaB4 O7 :Dy samples after ?-irradiation showed glow peaks at ~335, 530 and 675 K, with a heating rate of 2 K/s. The main peak at 530 K was analyzed using the Tmax -Tstop method and was found to be composed of at least five overlapping glow peaks. A curve-fitting program was used to perform computerized glow curve deconvolution (CGCD) analysis of the complex peak of the dosimetric material of interest. The kinetic parameters, namely activation energy (E) and frequency factor (s), associated with the main glow peak of CaB4 O7 :Dy at 520 K were evaluated using peak shape (PS) and isothermal luminescence decay (ILD) methods. In addition, the kinetics was determined to be first order (b =1) by applying the additive dose method. The activation energies and frequency factors obtained using PS and ILD methods are calculated to be 0.72 and 0.72 eV and 8.76 × 10(5) and 1.44 × 10(6) /s, respectively. Copyright © 2014 John Wiley & Sons, Ltd. PMID:25428760

  14. The measurement and analysis of electric fields in glow discharge plasmas

    SciTech Connect

    Lawler, J.E. [Univ. of Wisconsin, Madison, WI (United States); Doughty, D.A. [General Electric Company, Schenectady, NY (United States)

    1994-12-31

    Interest in glow discharge plasmas has remained high for many decades because of their widespread application as a source of incoherent and coherent light, in plasma processing materials, in pulsed power devices, and in other technologies. Plasma etching of semiconductors and various plasma deposition process emerged as major applications during the 1980s. The technological significance of plasma processing is described in Plasma Processing of Materials. More fundamental work on glow discharges also advanced greatly during the 1980s. For example, substantial progress was made through the use of laser diagnostics to study glow discharges and as a result of the dramatically increased computing power that became available in the 1980s to model glow discharges. Many of the laser diagnostics are described in Radiative Processes in Discharge Plasmas. Kinetic theory models, in particular, became far more sophisticated and realistic during the 1980s. This article is a review of recent work that used optical diagnostics to study electric fields in glow discharge plasmas. Alternative methods for measuring electric electric fields in plasmas include electron beam deflection and electrostatic probes. Optical techniques have important advantages over these methods: They can be used at higher pressures and discharge current densities than electron beam deflection; and they are noninvasive, unlike electrostatic probes. In addition, optical techniques are usually easier to apply in a highly pure system than either of the alternative methods. 46 refs., 23 figs., 1 tab.

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

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

    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.

  16. Mixing Of Mode Symmetries In Top Gated Bilayer And Multilayer Graphene Field Effect Devices

    NASA Astrophysics Data System (ADS)

    Chakraborty, Biswanath; Das, Anindya; Sood, A. K.

    2011-07-01

    We report Raman study to investigate the influence of stacking on the inversion symmetry breaking in top gated bi- and multi-layer (˜10 layers) graphene field effect transistors. The G phonon mode splits into a low frequency (Glow) and a high frequency (Ghigh) mode in bi- and multi-layer graphene and the two modes show different dependence on doping. The mode splitting is explained in terms of mixing of zone-center in-plane optical phonons representing in-phase and out-of-phase inter-layer atomic motions. Unlike in bilayer graphene, there is no transfer of intensity from Glow to Ghigh in multilayer graphene. A comparison is made for the bilayer graphene data with the recent theory of Gava et al. [Phys. Rev. B 80, 155422 (2009)].

  17. SWIR air glow mapping of the night sky

    NASA Astrophysics Data System (ADS)

    Myers, Michael M.; Dayton, David C.; Gonglewski, John D.; Fertig, Gregory; Allen, Jeff; Nolasco, Rudolf; Burns, Dennis; Mons, Ishan

    2010-08-01

    It is well known that luminance from photo-chemical reactions of hydroxyl ions in the upper atmosphere (~85 km altitude) produces a significant amount of night time radiation in the short wave infra-red (SWIR) band of wave length 0.9 to 1.7 ?m. Numerous studies of these phenomena have demonstrated that the irradiance shows significant temporal and spatial variations in the night sky. Changes in weather patterns, seasons, sun angle, moonlight, etc have the propensity to alter the SWIR air glow irradiance pattern. By performing multiple SWIR measurements a mosaic representation of the celestial hemisphere was constructed and used to investigate these variations over time and space. The experimental setup consisted of two sensors, an InGaAs SWIR detector and a visible astronomical camera, co-located and bore sighted on an AZ-EL gimbal. This gimbal was programmed to view most of the sky using forty five discrete azimuth and elevation locations. The dwell time at each location was 30 seconds with a total cycle time of less than 30 minutes. The visible astronomical camera collected image data simultaneous with the SWIR camera in order to distinguish SWIR patterns from clouds. Data was reduced through batch processing producing polar representations of the sky irradiance as a function of azimuth, elevation, and time. These spatiotemporal variations in the irradiance, both short and long term, can be used to validate and calibrate physical models of atmospheric chemistry and turbulence. In this paper we describe our experimental setup and present some results of our measurements made over several months in a rural marine environment on the Islands of Kauai and Maui Hawaii.

  18. SWIR Hemispherical Air-Glow Plotting System SHAPS

    NASA Astrophysics Data System (ADS)

    Gonglewski, John D.; Myers, Michael M.; Dayton, David C.; Fertig, Gregory; Allen, Jeffrey; Nolasco, Rudolph; Maia, Franscisco

    2010-10-01

    It is well known that luminance from photo-chemical reactions of hydroxyl ions in the upper atmosphere (~85 km altitude) produces a significant amount of night time radiation in the short wave infra-red (SWIR) band of wave length 0.9 to 1.7 ?m. Numerous studies of these phenomena have demonstrated that the irradiance shows significant temporal and spatial variations in the night sky. Changes in weather patterns, seasons, sun angle, moonlight, etc have the propensity to alter the SWIR air glow irradiance pattern. By performing multiple SWIR measurements a mosaic representation of the celestial hemisphere was constructed and used to investigate these variations over time and space. The experimental setup consisted of two sensors, an InGaAs SWIR detector and a visible astronomical camera, co-located and bore sighted on an AZ-EL gimbal. This gimbal was programmed to view most of the sky using forty five discrete azimuth and elevation locations. The dwell time at each location was 30 seconds with a total cycle time of less than 30 minutes. The visible astronomical camera collected image data simultaneous with the SWIR camera in order to distinguish SWIR patterns from clouds. Data was reduced through batch processing producing polar representations of the sky irradiance as a function of azimuth, elevation, and time. These spatiotemporal variations in the irradiance, both short and long term, can be used to validate and calibrate physical models of atmospheric chemistry and turbulence. In this paper we describe our experimental setup and present some results of our measurements made over several months in a rural marine environment on the Island of Kauai Hawaii.

  19. Laser/discharge interactions in glow-discharge mass spectrometry

    SciTech Connect

    Hess, K.R.

    1986-01-01

    Work in our laboratory has centered on the development of the glow discharge as an ionization source for solids elemental mass spectrometry. The electrical discharge produced by applying a large potential between a cathode, formed from the analytical sample, and an anode in the presence of a low pressure inert gas is known to generate ion signals and mass spectra representative of the sample composition. The acquisition of a tunable dye laser has allowed studies of various laser/discharge interactions to be performed. These include investigations into the laser opto-galvanic effect, resonance ionization, and laser ablation. The opto-galvanic effect, which involves monitoring changes in discharge resistance during the time period of laser interaction, was employed in a conjunction with atomic absorption and mass spectrometric studies to determine the major mechanisms of ionization in our discharge configuration. Laser depopulation of the rare gas metastable states was observed to decrease the ionization rate of the discharge, indicating a dependence on the metastable state in the ionization mechanisms. Although the discharge produces a large ion population, less than 1% of the total atomic density is ionized in the discharged. Therefore, a large neutral atomic population remains for interaction with the laser output. Resonant two photon absorption of the laser light can result in a wavelength selective enhancement of the ionization rate in the discharge source, with the enhancements occurring only at wavelengths corresponding to atomic transitions. This results in a technique that is both wavelength and mass selective, commonly termed resonance ionization mass spectrometry (RIMS). The laser can also serve to enhance the atomization of the discharge through laser ablation.

  20. Glow plasma trigger for electron cyclotron resonance ion sourcesa)

    NASA Astrophysics Data System (ADS)

    Vodopianov, A. V.; Golubev, S. V.; Izotov, I. V.; Nikolaev, A. G.; Oks, E. M.; Savkin, K. P.; Yushkov, G. Yu.

    2010-02-01

    Electron cyclotron resonance ion sources (ECRISs) are particularly useful for nuclear, atomic, and high energy physics, as unique high current generators of multicharged ion beams. Plasmas of gas discharges in an open magnetic trap heated by pulsed (100 ?s and longer) high power (100 kW and higher) high-frequency (greater than 37.5 GHz) microwaves of gyrotrons is promising in the field of research in the development of electron cyclotron resonance sources for high charge state ion beams. Reaching high ion charge states requires a decrease in gas pressure in the magnetic trap, but this method leads to increases in time, in which the microwave discharge develops. The gas breakdown and microwave discharge duration becomes greater than or equal to the microwave pulse duration when the pressure is decreased. This makes reaching the critical plasma density initiate an electron cyclotron resonance (ECR) discharge during pulse of microwave gyrotron radiation with gas pressure lower than a certain threshold. In order to reduce losses of microwave power, it is necessary to shorten the time of development of the ECR discharge. For fast triggering of ECR discharge under low pressure in an ECRIS, we initially propose to fill the magnetic trap with the plasmas of auxiliary pulsed discharges in crossed ExB fields. The glow plasma trigger of ECR based on a Penning or magnetron discharge has made it possible not only to fill the trap with plasma with density of 1012 cm-3, required for a rapid increase in plasma density and finally for ECR discharge ignition, but also to initially heat the plasma electrons to Te?20 eV.

  1. Glow plasma trigger for electron cyclotron resonance ion sources

    SciTech Connect

    Vodopianov, A. V.; Golubev, S. V.; Izotov, I. V. [Institute of Applied Physics, Russian Academy of Science, Nizhniy Novgorod 603950 (Russian Federation); Nikolaev, A. G.; Oks, E. M.; Savkin, K. P.; Yushkov, G. Yu. [High Current Electronics Institute, Siberian Division, Russian Academy of Science, Tomsk 634055 (Russian Federation)

    2010-02-15

    Electron cyclotron resonance ion sources (ECRISs) are particularly useful for nuclear, atomic, and high energy physics, as unique high current generators of multicharged ion beams. Plasmas of gas discharges in an open magnetic trap heated by pulsed (100 {mu}s and longer) high power (100 kW and higher) high-frequency (greater than 37.5 GHz) microwaves of gyrotrons is promising in the field of research in the development of electron cyclotron resonance sources for high charge state ion beams. Reaching high ion charge states requires a decrease in gas pressure in the magnetic trap, but this method leads to increases in time, in which the microwave discharge develops. The gas breakdown and microwave discharge duration becomes greater than or equal to the microwave pulse duration when the pressure is decreased. This makes reaching the critical plasma density initiate an electron cyclotron resonance (ECR) discharge during pulse of microwave gyrotron radiation with gas pressure lower than a certain threshold. In order to reduce losses of microwave power, it is necessary to shorten the time of development of the ECR discharge. For fast triggering of ECR discharge under low pressure in an ECRIS, we initially propose to fill the magnetic trap with the plasmas of auxiliary pulsed discharges in crossed ExB fields. The glow plasma trigger of ECR based on a Penning or magnetron discharge has made it possible not only to fill the trap with plasma with density of 10{sup 12} cm{sup -3}, required for a rapid increase in plasma density and finally for ECR discharge ignition, but also to initially heat the plasma electrons to T{sub e}{approx_equal}20 eV.

  2. Glow plasma trigger for electron cyclotron resonance ion sources.

    PubMed

    Vodopianov, A V; Golubev, S V; Izotov, I V; Nikolaev, A G; Oks, E M; Savkin, K P; Yushkov, G Yu

    2010-02-01

    Electron cyclotron resonance ion sources (ECRISs) are particularly useful for nuclear, atomic, and high energy physics, as unique high current generators of multicharged ion beams. Plasmas of gas discharges in an open magnetic trap heated by pulsed (100 micros and longer) high power (100 kW and higher) high-frequency (greater than 37.5 GHz) microwaves of gyrotrons is promising in the field of research in the development of electron cyclotron resonance sources for high charge state ion beams. Reaching high ion charge states requires a decrease in gas pressure in the magnetic trap, but this method leads to increases in time, in which the microwave discharge develops. The gas breakdown and microwave discharge duration becomes greater than or equal to the microwave pulse duration when the pressure is decreased. This makes reaching the critical plasma density initiate an electron cyclotron resonance (ECR) discharge during pulse of microwave gyrotron radiation with gas pressure lower than a certain threshold. In order to reduce losses of microwave power, it is necessary to shorten the time of development of the ECR discharge. For fast triggering of ECR discharge under low pressure in an ECRIS, we initially propose to fill the magnetic trap with the plasmas of auxiliary pulsed discharges in crossed ExB fields. The glow plasma trigger of ECR based on a Penning or magnetron discharge has made it possible not only to fill the trap with plasma with density of 10(12) cm(-3), required for a rapid increase in plasma density and finally for ECR discharge ignition, but also to initially heat the plasma electrons to T(e) approximately = 20 eV. PMID:20192326

  3. 1624 IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. 26, NO. 9, SEPTEMBER 1990 Recombination Lasers in a Flowing Negative Glow

    E-print Network

    Rocca, Jorge J.

    negative glow discharge is to our knowledge the only device in which prolonged CW recombination laser in a Flowing Negative Glow Discharge B. WERNSMAN, JORGE J. ROCCA, MEMBER, IEEE, HECTOR L. MANCINI, DANIEL-stateconditions. A 4 em long flowing hollow cathode discharge was used to obtain CW recombina- tion laser oscillation

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

    Microsoft Academic Search

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

    2007-01-01

    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

  5. IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. 28. NO. 9. SEPTEMBER 1992 1941 A Self-Consistent Model for Negative Glow

    E-print Network

    Rocca, Jorge J.

    geometry and material, the discharge voltage, and the partial pressures of the buffer gas and the metal for Negative Glow Discharge Lasers: The Hollow Cathode Helium Mercury Laser Gregory J. Fetzer, Member, IEEE-consistently describes the dynamics of the negative glow and the cathode sheath regions of the discharge has been

  6. Simulation of the shielding of dust particles in low pressure glow Seung J. Choi and Mark J. Kushner

    E-print Network

    Kushner, Mark

    Simulation of the shielding of dust particles in low pressure glow discharges Seung J. Choi) The dynamics of the shielding of particulates ("dust") in low pressure glow discharges have been investigated sections represented by the geometrical obscuration of the charged dust particles and their shield- ing

  7. Requirements of the glow discharge techniques to the fundamentals - an exemplary approach.

    PubMed

    Broekaert, J A

    1996-07-01

    The importance of gaining knowledge on the fundamental processes in glow discharges in the field of the signal generation, the sputtering phenomena taking place in the case of solids and the analyte breakdown in the excitation of gases is treated. For gaining more knowledge on the plasma processes diagnostics including temperature and electron number density as well as gas and analyte atom and ion densities are required. For the sputtering process, it is shown at the hand of measurements with gas-jet enhanced sputtering and magnetically enhanced sputtering that selective sputtering may occur and that the influence of the analyte loading of the glow discharge plasma needs further study. For the case of the introduction of gaseous samples, the analyte distribution as well as the break-down mechanisms and kinetics in the case of molecular species ask for further study as shown by experiments with gas-sampling glow discharges. PMID:15045277

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

    NASA Astrophysics Data System (ADS)

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

    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.

  9. Laser-excited atomic fluorescence in a pulsed hollow-cathode glow discharge.

    PubMed

    Glick, M; Smith, B W; Winefordner, J D

    1990-01-15

    A pulsed glow discharge with low background noise is evaluated as an atom reservoir for laser-induced atomic fluorescence spectroscopy. Aqueous solutions are dried in graphite electrodes that are used as disposable hollow cathodes. Atomic vapor is produced in a flowing-gas glow discharge with a water-cooled cathode holder. A dye laser triggers a switching circuit that pulses that glow discharge, and fluorescence measurements are made 100 microseconds after the discharge is extinguished. The atomic population is large during this dark period, while the background emission is negligible. Linear calibration curves are obtained by nonresonance fluorescence for two elements, Pb and Ir. The detection limits for Pb are 100 pg/mL and 500 fg, and for Ir are 6 ng/mL and 20 pg. The experimental detection limit for Pb is compared to the intrinsic detection limit. PMID:2310012

  10. Mastoid abnormalities in down syndrome

    Microsoft Academic Search

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

    1989-01-01

    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

  11. Infertile mares with chromosome abnormalities

    Microsoft Academic Search

    I. A. Stewart-Scott

    1988-01-01

    Chromosomal abnormalities have been detected in five mares identified by their poor reproductive performance. All had small gonads and absent or irregular oestrous cycles. One mare was 65, XXX, two were 64, XY sex-reversal females and two were sex chromosome mosaics with karyotypes of 63, XO\\/64, XX\\/64, XY and 63, XO\\/64, XX respectively. This report supports the suggestion made in

  12. Atlas: Cartilage Abnormalities and Scores

    Microsoft Academic Search

    Hans Liebl; Thomas M. Link

    \\u000a The following chapter illustrates cartilage abnormalities and provides semiquantitative scores for these lesions. The focus\\u000a of this chapter is on the most frequently used Recht (modified Noyes and Stabler) score [1, 2] and Whole-Organ-MRI-Score (WORMS)\\u000a [3]. These scores have been used in a number of previous studies and have been found helpful in assessing the grade of cartilage\\u000a lesions, in

  13. Ovarian Steroidogenic Abnormalities in PCOS

    Microsoft Academic Search

    Jessica K. Wickenheisser; Jan M. McAllister

    Androgen excess, theca, granulosa, polycystic ovary syndrome, steroidogenesis, folliculogenesis, estrogen, insulin sensitivity,\\u000a signaling defect. Polycystic ovary syndrome (PCOS) is a common, clinically heterogeneous disorder that affects approximately\\u000a 6–10% of premenopausal women [1, 2]. Hyperandrogenemia is the biochemical hallmark of PCOS. Reproductive and endocrine abnormalities\\u000a include disordered gonadotropin secretion, oligomenorrhea and anovulatory infertility, and endometrial hyperplasia. Obesity,\\u000a hirsutism, acne, and alopecia

  14. Combining Registration and Abnormality Detection in Mammography

    E-print Network

    Desolneux, Agnès

    Combining Registration and Abnormality Detection in Mammography Mohamed Hachama, Agn`es Desolneux (e.g. lesions) in mammography are solved separately, although the solutions of these problems 2006 #12;Combining Registration and Abnormality Detection in Mammography 179 The definition

  15. A study of glow-discharge and permeation techniques for extraterrestrial oxygen beneficiation

    NASA Astrophysics Data System (ADS)

    Ash, R. L.; Wu, D.; Outlaw, R. A.

    1994-06-01

    Extraction of oxygen from Martian atmosphere and compression of lunar oxygen can utilize stabilized zirconia electrochemical pumps. Silver membranes can be used as electrodes to increase oxygen yield at relatively low temperatures. This study has investigated oxygen permeation through Ag 0.05Zr membranes with glow-discharge assisted disassociation. Data show that the overall process is controlled by bulk diffusion but the slow dissociative adsorption onto the surface limited the overall transport substantially. With glow-discharge assisted dissociation, an order of magnitude increase in oxygen throughput can be produced at relatively low temperatures (450-550C).

  16. An XPS study of the KCl surface oxidation in oxygen glow discharge

    NASA Astrophysics Data System (ADS)

    Stoch, J.; Ladecka, M.

    1988-05-01

    The reaction between the surface of KCl and oxygen in a glow discharge has been studied by X-ray photoemission spectroscopy (XPS). Oxygen glow discharge treatment resulted in the formation of a superoxide, which decomposed under vacuum at room temperature to KO 2 and finally to K 2O. No evidence of KClO 3 or KClO 4 formation has been found. Binding energies of some oxygen species in potassium oxides were determined. The possible role of potassium in K-doped silver catalysts of ethylene epoxidation is discussed.

  17. Emission intensity modulation of radio-frequency helium glow-discharge emission source by laser ablation.

    PubMed

    Matsuta, Hideyuki; Naeem, Tariq M; Wagatsuma, Kazuaki

    2003-06-01

    A novel emission excitation source comprising a high repetition rate diode-pumped Q-switched Nd:YAG laser and a Grimm-style glow-discharge lamp is described. Laser-ablated atoms are introduced into the He glow discharge plasma, which then give emission signals. By using phase-sensitive detection with a lock-in amplifier, the emission signal modulated by the pulsed laser can be detected selectively. It is possible to estimate only the emission intensity of sample atoms ablated by laser irradiation with little interference from the other species in the plasma. PMID:12834217

  18. Optical and electrical characterization of C3H6O/Ar glow discharge

    NASA Astrophysics Data System (ADS)

    Villalobos, S.; Castillo, F.; Flores, O.; Reyes, P. G.; Martínez, H.

    2015-03-01

    A low pressure glow discharge apparatus was used to produce a glow discharge of C3H6O/Ar mixture at a total pressure of 2.0 Torr. The emission spectra were measured in the wavelength range of 200 to 1100 nm. The principal species observed were Ar I, C6H4O, C6H5, CHO, CH3O, CO2, CO, H2O, and H2. The electron temperature and ion density have been measured using a double Langmuir probe, and the electron temperature and ion density were found in the order of 10 eV and 1010 cm-3.

  19. Detrapping of tungsten nanoparticles in a direct-current argon glow discharge

    NASA Astrophysics Data System (ADS)

    Couëdel, L.; Kumar K., Kishor; Arnas, C.

    2014-12-01

    Nanoparticles are grown from the sputtering of a tungsten cathode in a direct current argon glow discharge. Laser light scattering of a vertical laser sheet going through the plasma reveals that the dust particle cloud is compressed and pushed towards the anode during the discharge. Scanning electron microscopy images of substrates exposed to the plasma for given durations show that dust particles are continuously falling down on the anode during the discharge. These observations are explained by the fact that the electrostatic force at the negative glow-anode sheath boundary cannot balance the ion drag, gravity, and thermophoresis forces for particles of more than a few tens of nanometres in diameter.

  20. Nanosecond Glow and Spark Discharges in Ambient Air and in Water Vapor

    NASA Astrophysics Data System (ADS)

    Laux, Christophe; Rusterholtz, Diane; Sainct, Florent; Xu, Da; Lacoste, Deanna; Stancu, Gabi; Pai, David

    2013-09-01

    Nanosecond repetitively pulsed (NRP) discharges are one of the most energy efficient ways to produce active species in atmospheric pressure gases. In both air and water vapor, three discharge regimes can be obtained: 1) corona, with light emission just around the anode, 2) glow, corresponding to a diffuse nonequilibrium plasma, and 3) spark, characterized by higher temperatures and higher active species densities. The glow regime was initially obtained in air preheated at 2000 K. Based on a model defining the transition between glow and spark, we recently succeeded in obtaining a stable glow in ambient air at 300 K, using a judicious combination of electrode geometry, pulse duration, pulse frequency, and applied voltage. We will present these results and describe the characteristics of the discharge obtained in room air. The spark regime was also studied. NRP sparks induce ultrafast gas heating (about 1000 K in 20 ns) and high oxygen dissociation (up to 50% dissociation of O2) . This phenomenon can be explained by a two-step process involving the excitation of molecular nitrogen followed by exothermic dissociative quenching of molecular oxygen. The characteristics of NRP discharges in water vapor will also be discussed. Nanosecond repetitively pulsed (NRP) discharges are one of the most energy efficient ways to produce active species in atmospheric pressure gases. In both air and water vapor, three discharge regimes can be obtained: 1) corona, with light emission just around the anode, 2) glow, corresponding to a diffuse nonequilibrium plasma, and 3) spark, characterized by higher temperatures and higher active species densities. The glow regime was initially obtained in air preheated at 2000 K. Based on a model defining the transition between glow and spark, we recently succeeded in obtaining a stable glow in ambient air at 300 K, using a judicious combination of electrode geometry, pulse duration, pulse frequency, and applied voltage. We will present these results and describe the characteristics of the discharge obtained in room air. The spark regime was also studied. NRP sparks induce ultrafast gas heating (about 1000 K in 20 ns) and high oxygen dissociation (up to 50% dissociation of O2) . This phenomenon can be explained by a two-step process involving the excitation of molecular nitrogen followed by exothermic dissociative quenching of molecular oxygen. The characteristics of NRP discharges in water vapor will also be discussed. This work is supported by the ANR PREPA program (grant number ANR-09-BLAN-0043).

  1. Double Glow Plasma Surface Alloying Antibacterial Silver Coating on Pure Titanium

    NASA Astrophysics Data System (ADS)

    Lin, Naiming; Guo, Junwen; Hang, Ruiqiang; Zou, Jiaojuan; Tang, Bin

    2014-12-01

    In order to endow the commercial pure titanium dental implant material with antibacterial property and aimed at avoiding the invalidation that is caused by bacterial adhesion on the surface, a silver coating was fabricated via double glow plasma surface alloying. The antibacterial property of the silver coating was assessed via in vitro estimation. The results showed that a continuous and compact coating was formed. The silver coating had absolute superiority in antibacterial property to raw commercial pure titanium. Double glow plasma surface alloying with silver on commercial pure titanium dental implant material could be considered as a potentially effective method for preventing bacterial adhesion.

  2. Double Glow Plasma Surface Alloying Antibacterial Silver Coating on Pure Titanium

    NASA Astrophysics Data System (ADS)

    Lin, Naiming; Guo, Junwen; Hang, Ruiqiang; Zou, Jiaojuan; Tang, Bin

    2014-03-01

    In order to endow the commercial pure titanium dental implant material with antibacterial property and aimed at avoiding the invalidation that is caused by bacterial adhesion on the surface, a silver coating was fabricated via double glow plasma surface alloying. The antibacterial property of the silver coating was assessed via in vitro estimation. The results showed that a continuous and compact coating was formed. The silver coating had absolute superiority in antibacterial property to raw commercial pure titanium. Double glow plasma surface alloying with silver on commercial pure titanium dental implant material could be considered as a potentially effective method for preventing bacterial adhesion.

  3. Long range temporal correlation in the chaotic oscillations of a dc glow discharge plasma

    SciTech Connect

    Lahiri, S. [Dinabandhu Mahavidyalaya, Bongaon, North 24 Parganas, Kolkata 743235 (India); Roychowdhury, D. [Techno India, EM4/1 Sector V, Salt Lake, Kolkata 700091 (India); Sekar Iyengar, A. N. [Plasma Physics Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064 (India)

    2012-08-15

    Long range temporal correlations in the fluctuations of the plasma floating potentials (measured using a Langmuir probe) are investigated in a dc glow discharge plasma. Keeping the neutral pressure constant, the discharge voltage was varied and at the formation of the plasma, quasi periodic oscillations were excited and on further increase of the discharge voltage they became chaotic (irregular) beyond a threshold voltage. We compared the Lyapunov exponent with the Hurst exponent obtained from R/S statistics which showed an opposite behaviour at the transition point. These results are perhaps new since we have not come across such comparative analysis for chaotic oscillations in a glow discharge plasma before.

  4. Abnormal Supranuclear Eye Movements in the Child

    Microsoft Academic Search

    Lorraine Cassidy; David Taylor; Christopher Harris

    2000-01-01

    Abnormal eye movements in the infant or young child can be congenital or acquired. They may be a result of abnormal early visual development or a sign of underlying neurologic or neuromuscular disease. It is important to be able to detect these abnormalities and to distinguish them from normal but immature eye movements. The spectrum of disease in children differs

  5. EUVE observations of the helium glow: Interstellar and solar parameters

    NASA Astrophysics Data System (ADS)

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

    2004-11-01

    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.

  6. Nonosseous abnormalities on bone scans.

    PubMed

    Loutfi, Issa; Collier, B David; Mohammed, Ahmed M

    2003-09-01

    Although bone scanning is a test primarily concerned with skeletal abnormalities, important nonosseous findings are occasionally present on the images. To gauge the significance of such nonosseous uptake and, in particular, to determine whether these findings contain useful diagnostic information, the technical and medical staff in nuclear medicine must recognize the various patterns of nonbony uptake and understand their causes. The objectives of this article are to demonstrate the appearances of nonosseous uptake on bone scans, to categorize the forms of soft-tissue uptake, to emphasize technical artifacts leading to soft-tissue uptake, and to highlight the clinical significance of pathologic soft-tissue uptake. PMID:12968045

  7. Foot abnormalities of wild birds

    USGS Publications Warehouse

    Herman, C.M.; Locke, L.N.; Clark, G.M.

    1962-01-01

    The various foot abnormalities that occur in birds, including pox, scaly-leg, bumble-foot, ergotism and freezing are reviewed. In addition, our findings at the Patuxent Wildlife Research Center include pox from dove, mockingbird, cowbird, grackle and several species of sparrows. Scaly-leg has been particularly prevalent on icterids. Bumble foot has been observed in a whistling swan and in a group of captive woodcock. Ergotism is reported from a series of captive Canada geese from North Dakota. Several drug treatments recommended by others are presented.

  8. Abnormalities of the erythrocyte membrane.

    PubMed

    Gallagher, Patrick G

    2013-12-01

    Primary abnormalities of the erythrocyte membrane are characterized by clinical, laboratory, and genetic heterogeneity. Among this group, hereditary spherocytosis patients are more likely to experience symptomatic anemia. Treatment of hereditary spherocytosis with splenectomy is curative in most patients. Growing recognition of the long-term risks of splenectomy has led to re-evaluation of the role of splenectomy. Management guidelines acknowledge these considerations and recommend discussion between health care providers, patient, and family. The hereditary elliptocytosis syndromes are the most common primary disorders of erythrocyte membrane proteins. However, most elliptocytosis patients are asymptomatic and do not require therapy. PMID:24237975

  9. Pathology Case Study: Sensory Abnormalities

    NSDL National Science Digital Library

    Duggal, Neil

    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 patientâ??s 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.

  10. The Rose-red Glow of Star Formation

    NASA Astrophysics Data System (ADS)

    2011-03-01

    The vivid red cloud in this new image from ESO's Very Large Telescope is a region of glowing hydrogen surrounding the star cluster NGC 371. This stellar nursery lies in our neighbouring galaxy, the Small Magellanic Cloud. The object dominating this image may resemble a pool of spilled blood, but rather than being associated with death, such regions of ionised hydrogen - known as HII regions - are sites of creation with high rates of recent star birth. NGC 371 is an example of this; it is an open cluster surrounded by a nebula. The stars in open clusters all originate from the same diffuse HII region, and over time the majority of the hydrogen is used up by star formation, leaving behind a shell of hydrogen such as the one in this image, along with a cluster of hot young stars. The host galaxy to NGC 371, the Small Magellanic Cloud, is a dwarf galaxy a mere 200 000 light-years away, which makes it one of the closest galaxies to the Milky Way. In addition, the Small Magellanic Cloud contains stars at all stages of their evolution; from the highly luminous young stars found in NGC 371 to supernova remnants of dead stars. These energetic youngsters emit copious amounts of ultraviolet radiation causing surrounding gas, such as leftover hydrogen from their parent nebula, to light up with a colourful glow that extends for hundreds of light-years in every direction. The phenomenon is depicted beautifully in this image, taken using the FORS1 instrument on ESO's Very Large Telescope (VLT). Open clusters are by no means rare; there are numerous fine examples in our own Milky Way. However, NGC 371 is of particular interest due to the unexpectedly large number of variable stars it contains. These are stars that change in brightness over time. A particularly interesting type of variable star, known as slowly pulsating B stars, can also be used to study the interior of stars through asteroseismology [1], and several of these have been confirmed in this cluster. Variable stars play a pivotal role in astronomy: some types are invaluable for determining distances to far-off galaxies and the age of the Universe. The data for this image were selected from the ESO archive by Manu Mejias as part of the Hidden Treasures competition [2]. Three of Manu's images made the top twenty; his picture of NGC 371 was ranked sixth in the competition. Notes [1] Asteroseismology is the study of the internal structure of pulsating stars by looking at the different frequencies at which they oscillate. This is a similar approach to the study of the structure of the Earth by looking at earthquakes and how their oscillations travel through the interior of the planet. [2] ESO's Hidden Treasures 2010 competition gave amateur astronomers the opportunity to search through ESO's vast archives of astronomical data, hoping to find a well-hidden gem that needed polishing by the entrants. Participants submitted nearly 100 entries and ten skilled people were awarded some extremely attractive prizes, including an all expenses paid trip for the overall winner to ESO's Very Large Telescope (VLT) on Cerro Paranal, in Chile, the world's most advanced optical telescope. The ten winners submitted a total of 20 images that were ranked as the highest entries in the competition out of the near 100 images. More information ESO, the European Southern Observatory, is the foremost intergovernmental astronomy organisation in Europe and the world's most productive astronomical observatory. It is supported by 15 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO op

  11. Glow-to-arc transition at the left branch of the Paschen-curve

    Microsoft Academic Search

    J. Rossignol; B. Jiittner; C. H. Wu

    2002-01-01

    The glow-to-arc transition in deuterium at pressures p ? 10 mbar has been investigated experimentally with high time resolution (10 ns) by using a high-speed image converter camera and a 1 GHz digital oscilloscope. The electrodes were made from graphite with different compositions. The following observations have been made: (i) at currents > 1 A an anode spot is formed

  12. PSpice simulation of one atmosphere uniform glow discharge plasma (OAUGDP) reactor systems

    Microsoft Academic Search

    Zhiyu Chen

    2003-01-01

    The PSpice software has been used to simulate the electrical characteristics of a one atmosphere uniform glow discharge plasma (OAUGDP) reactor system. An OAUGDP reactor system normally includes a power supply, a transformer, an impedance matching network, and the plasma reactor. The principal task in simulation is to develop a comprehensive PSpice model for the plasma discharge in an OAUGDP

  13. The influence of LF glow discharge treatment on the dielectric properties of PET film

    Microsoft Academic Search

    Alexander Drachev; Vladimir Pak; Alla Gilman; Alexander Kuznetsov

    2002-01-01

    The influence of low frequency glow discharge treatment on the dielectric properties of. PET film (loss angle and permittivity) was studied over a wide range of frequencies and temperatures. It was shown that the treatment of PET film does not influence the loss angle in the interval of frequencies 100 Hz-3 MHz and at temperatures from 20°C to 200°C: The

  14. Plasma parameters and chemical kinetics of an HCl DC glow discharge

    Microsoft Academic Search

    A. M. Efremov; G. H. Kim; D. I. Balashov; C. I. Kim

    2006-01-01

    The investigations of plasma parameters and active particles kinetics in an HCl DC glow discharge system were carried out. The investigation combines plasma diagnostics by electric probes and plasma modeling based on the self-consistent solution of Boltzmann kinetic equation and the balance equation of chemical kinetic for neutral and charged particles. It was shown that the direct electron impact dissociation

  15. Deposition of super-hydrophobic fluorocarbon coatings in modulated RF glow discharges

    Microsoft Academic Search

    P. Favia; G. Cicala; A. Milella; F. Palumbo; P. Rossini; R. d'Agostino

    2003-01-01

    Superhydrophobic coatings were deposited in modulated RF glow discharges fed with tetrafluorothylene. Such coatings are characterized by a high fluorination degree, ribbon-like randomly distributed surface microstructures, and a certain crystallinity. Combined high fluorination degree and surface texture\\/roughness leads to the super hydrophobic behaviour, as attested by water contact angle values of 150° and more. The coatings were characterized by means

  16. Two-dimensional simulations of the transition from Townsend to glow discharge and subnormal oscillations

    Microsoft Academic Search

    Robert R. Arslanbekov; Vladimir I. Kolobov

    2003-01-01

    The transition from Townsend to glow discharge is studied via two-dimensional simulations of discharges with moderate pd values corresponding to the right branch of the Paschen curve (p is the gas pressure and d the electrode spacing). The discharge model is coupled to the external circuit model enabling simulations of subnormal oscillations during the discharge transition from the Townsend to

  17. Notice to nurserymen of the naming and release for propagation of Ebony Glow crapemyrtle

    Technology Transfer Automated Retrieval System (TEKTRAN)

    UNITED STATES DEPARTMENT OF AGRICULTURE Agricultural Research Service Washington, D.C. and MISSISSIPPI STATE UNIVERSITY Starkville, MS NOTICE TO NURSERYMEN OF THE NAMING AND RELEASE FOR PROPAGATION OF ‘EBONY GLOW’ CRAPE MYRTLE The United States Department of Agriculture, Agricultural Research S...

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

    Microsoft Academic Search

    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

    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.

  19. Influences of shock waves on high-pressure, pulsed glow discharge for excimer laser excitation

    Microsoft Academic Search

    G. Imada; H. Yamanoi; M. Suzuki; W. Masuda; K. Yatsui

    2000-01-01

    The high-pressure, pulsed glow discharge has been studied for further understanding of the excitation discharge on excimer lasers. The influences of shock waves on the discharge have been investigated eliminating the other factors, which may affect the discharge instabilities, such as gas density depletion, discharge products, residual ions and electrode heating. A shock wave of 1.2 in Mach number is

  20. Method to measure the electric field vector in an argon glow discharge using laser polarization spectroscopy

    Microsoft Academic Search

    V. P. Gavrilenko; H. J. Kim; T. Ikutake; J. B. Kim; M. D. Bowden; K. Muraoka

    2001-01-01

    A method for measurement of the direction of the electric field in a glow discharge is reported. This method uses the dependence of the electronic excitation spectrum of argon atoms on the polarization of the laser radiation. In this research, laser radiation was used to excite argon atoms in a plasma from the 4s [32]2 metastable level to Rydberg levels,

  1. The measurement and analysis of electric fields in glow discharge plasmas

    Microsoft Academic Search

    J. E. Lawler; D. A. Doughty

    1994-01-01

    Interest in glow discharge plasmas has remained high for many decades because of their widespread application as a source of incoherent and coherent light, in plasma processing materials, in pulsed power devices, and in other technologies. Plasma etching of semiconductors and various plasma deposition process emerged as major applications during the 1980s. The technological significance of plasma processing is described

  2. Pulse striations in glow discharge generated by a laser ablation plume

    Microsoft Academic Search

    Y. Hoshi; H. Yoshida; Y. Tsutsui

    2002-01-01

    A unique form of striations, pulse striations, has been observed in a glow discharge by means of a laser-triggered pulse. Unlike conventional striations in a discharge tube, pulse striations are generated near an anode placed in free space. Pulse striations are stereoscopic in shape, appear static, and have a relatively short lifetime of around 1 ms. The wavelength of striations

  3. Stabilization of the emitting power of glow-discharge lasers and their applications

    Microsoft Academic Search

    V. E. Privalov; E. A. Smirnov

    1986-01-01

    Perturbations occurring in gas-discharge lasers, their effect on emitting power stability, and methods of emission stabilization are briefly reviewed, with particular attention given to glow-discharge lasers. Emphasis is placed on power stabilization methods that are based on the correlation between the lasing power and the discharge current. These methods are simple to implement, are characterized by lower emission losses in

  4. Improved Signal-to-noise Ratio in Glow Discharge Ion Trap Mass Spectrometryvia Pulsed Discharge Operation

    Microsoft Academic Search

    DOUGLAS C. DUCKWORTH; DAVID H. SMITH; SCOTT A. MCLUCKEY

    1997-01-01

    An improvement in the S\\/N ratio is reported for the analysis ence of intense matrix and discharge gas (Ar) ion beams.9 This of trace elements in brass by glow discharge ion trap mass observation was important because it allowed the dynamic spectrometry. This was achieved by synchronizing the pulsed range of the trap, which has an ion volume limited to

  5. Electric field distribution in the cathode sheath of an electron beam glow discharge

    Microsoft Academic Search

    S. A. Lee; L.-U. A. Andersen; J. J. Rocca; M. Marconi; N. D. Reesor

    1987-01-01

    We have measured the electric field distribution in the cathode sheath of an electron beam He glow discharge. Laser saturation spectroscopy was used to determine the quadratic Stark shift produced by the electric field. The experimental results are in good agreement with the calculations of a collisional model of the cathode sheath.

  6. Study of laser resonance ionization mass spectrometry using a glow discharge source

    SciTech Connect

    Xiong, X. [National Inst. of Standards and Technology, Gaithersburg, MD (United States)]|[Eastern Analytical, Inc., College Park, MD (United States); Hutchinson, J.M.R.; Fassett, J.D.; Lucatorto, T.B.; Schima, F.J.; Bowman, W.A. [National Inst. of Standards and Technology, Gaithersburg, MD (United States); Hess, K.R. [Franklin and Marshall Coll., Lancaster, PA (United States). Dept. of Chemistry

    1994-09-01

    The mass spectra of a metal alloy sample consisting of Al, Cu and Fe were studied using both glow discharge mass spectrometry (GDMS) and resonance ionization mass spectrometry (RIMS). Particular emphasis was placed on the reduction of isobaric interferences and discrimination between those ions formed by the discharge and those formed by the laser radiation.

  7. Morphology of titanium nitride produced using glow discharge nitriding, laser remelting and pulsed laser deposition

    Microsoft Academic Search

    M Golebiewski; G. Kru?el; R. Major; W. Mróz; T. Wierzcho?; R. Ebner; B. Major

    2003-01-01

    Surface layers, produced on titanium alloys by means of glow discharge nitriding, laser modification by remelting using Nd:YAG or diode lasers in nitrogen environment and pulsed laser deposition by titanium target ablation in nitrogen environment, have been studied. Residual stresses were measured using an X-ray method and their values were related to the type of the applied technological process.

  8. High pressure glow discharges for nanosecond excitation of gas lasers and low inductance switching applications

    Microsoft Academic Search

    V. Hasson; H. M. von Bergmann

    1976-01-01

    The authors describe a novel method of producing uniform high pressure glow discharges suitable for nanosecond excitation of gas lasers and for low inductance, high voltage switching applications. The principle has been adapted to a variety of different gases with established and potential laser applications and is particularly well suited to the stabilization of transverse discharges. Stabilization can be effected

  9. Measurement of Negative Ion Density in an Oxygen DC Glow Discharge by Optogalvanic Photodetachment Spectroscopy

    Microsoft Academic Search

    Yoshinobu Matsuda; Hitomi Nagamatsu; Hiroshi Fujiyama

    1998-01-01

    We measured the local density of oxygen negative ions (O^-, O_2^-) in an O2 dc glow discharge by laser optogalvanic photedetachment spectroscopy. The advantages of the photedetachment spectroscopy are its simplicity, quantitative capability for density evaluation, and straightforward data analysis compared with other diagnostics. However, the use of a probe for collecting photodetached electrons in reactive plasma environment, a careful

  10. Study of laser resonance ionization mass spectrometry using a glow discharge source

    SciTech Connect

    Xiong, X.; Hutchinson, J. M. R.; Fassett, J. D.; Lucatorto, T. B.; Schima, F. J.; Bowman, W. A.; Hess, K. R. [National Institute of Standards and Technology, Gaithersburg, Maryland (United States); Eastern Analytical, Inc., 335 Paint Branch Dr., College Park, Maryland (United States); National Institute of Standards and Technology, Gaithersburg, Maryland (United States); Department of Chemistry, Franklin and Marshall College, Lancaster, Pennsylvania (United States)

    1995-04-01

    The mass spectra of a metal alloy sample consisting of Al, Cu and Fe were studied using both glow discharge mass spectrometry (GDMS) and resonance ionization mass spectrometry (RIMS). Particular emphasis was placed on the reduction of isobaric interferences and discrimination between those ions formed by the discharge and those formed by the laser radiation.

  11. Influences of Shock Waves on High-Pressure, Pulsed Glow Discharge due to Excimer Laser Excitation

    Microsoft Academic Search

    Go Imada; Hiroshi Yamanoi; Masataro Suzuki; Wataru Masuda; Kiyoshi Yatsui

    2001-01-01

    The high-pressure, pulsed glow discharge has been studied to gain a further understanding of the excitation discharge on application of excimer lasers. The influence of shock waves on the discharge has been investigated disregarding other factors which may affect the discharge instabilities, such as gas density depletion, discharge products, residual ions, halogen gas, and electrode heating. A shock wave of

  12. Effective glow discharge excitation of nitrogen lasers at gas pressures ranging from 0 to 5 bar

    Microsoft Academic Search

    V. Hasson; H. M. von Bergmann; D. Preussler

    1976-01-01

    This paper applies a novel stabilization technique to the effective glow discharge excitation of UV nitrogen lasers at gas pressures ranging from 0 to 5 bar. The plasma is produced between uniform field electrodes and can be stabilized at electrode separations of down to 1 mm. The stabilization is relatively insensitive to the electrode geometry and surface finish. Megawatt pulses

  13. Independent initiation technique of glow discharge production in high-pressure gas laser cavities

    Microsoft Academic Search

    O. Farish; R. L. Hundstad

    1978-01-01

    A trigger circuit which operates independently of the main discharge circuit can be used to initiate glow discharge useful for gas laser excitation. By utilizing independent trigger means, such as auxiliary dielectric electrodes, the main discharge can be controlled by modulating only a small part of the total energy input to the laser cavity. The main discharge gap of the

  14. Compact Hg II laser excited by a transverse electron beam glow discharge

    SciTech Connect

    Rocca, J.J.; Collins, G.J.; McClure, D.M.

    1983-10-01

    CW laser action at an output power of 6 mW has been obtained on the 6149.5 A transition of Hg II, using a 10 cm long transverse electron beam glow discharge. Beam energies are typically 1 keV. Laser tube design, discharge characteristics, and laser output power are reported.

  15. High explosives vapor detection by atmospheric sampling glow discharge ionization/tandem mass spectrometry

    SciTech Connect

    McLuckey, S.A.; Goeringer, D.E.; Asano, K.G. [Oak Ridge National Lab., TN (United States). Chemical and Analytical Sciences Div.

    1996-02-01

    The combination of atmospheric sampling glow discharge ionization with tandem mass spectrometry for the detection of traces of high explosives is described. Particular emphasis is placed on use of the quadrupole ion trap as the type of tandem mass spectrometer. Atmospheric sampling glow discharge provides a simple, rugged, and efficient means for anion formation while the quadrupole ion trap provides for efficient tandem mass spectrometry. Mass selective ion accumulation and non-specific ion activation methods can be used to overcome deleterious effects arising from ion/ion interactions. Such interactions constitute the major potential technical barrier to the use of the ion trap for real-time monitoring of targeted compounds in uncontrolled and highly variable matrices. Tailored waveforms can be used to effect both mass selective ion accumulation and ion activation. Concatenated tailored waveforms allow for both functions in a single experiment thereby providing the capability for monitoring several targeted species simultaneously. The combination of atmospheric sampling glow discharge ionization with a state-of-the-art analytical quadrupole ion trap is a highly sensitive and specific detector for traces of high explosives. The combination is also small and inexpensive relative to virtually any other form of tandem mass spectrometry. The science and technology underlying the glow discharge/ion trap combination is sufficiently mature to form the basis for an engineering effort to make the detector portable. 85 refs.

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

    Microsoft Academic Search

    Hodaka Osawa; Shigehisa Yoshimura; Takehiro Tabata; Masami Ohnishi

    2008-01-01

    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

  17. Cd-Ne direct current glow discharge: An efficient source of ultraviolet radiation

    Microsoft Academic Search

    G. M. Petrov; Ts. Petrova; A. Ogoyski; A. B. Blagoev

    2000-01-01

    This investigation aims to present data of a potential light source based on Cd. Recent study of cadmium-neon direct current glow discharge at low and intermediate pressure showed that a significant fraction (~80%) of the input power delivered to the plasma can be converted into resonance radiation, which leads us to conclusion that Cd can be an efficient light source,

  18. Cd–Ne direct current glow discharge: An efficient source of ultraviolet radiation

    Microsoft Academic Search

    G. M. Petrov; Ts. Petrova; A. Ogoyski; A. B. Blagoev

    2000-01-01

    This investigation aims to present data of a potential light source based on Cd. Recent study of cadmium–neon direct current glow discharge at low and intermediate pressure showed that a significant fraction (?80%) of the input power delivered to the plasma can be converted into resonance radiation, which leads us to conclusion that Cd can be an efficient light source,

  19. Investigation of the anisotropic electron distribution function in a glow discharge in hydrogen

    Microsoft Academic Search

    Yu. B. Pankrashkin; M. B. Shapochkin

    2003-01-01

    Results are presented from measurements of the electron distribution function in a glow discharge in hydrogen with the help\\u000a of a plane probe by the second-harmonic method. The parameters are determined for a model description of the distribution\\u000a function of thermal and suprathermal electrons.

  20. Images of biological samples undergoing sterilization by a glow discharge at atmospheric pressure

    Microsoft Academic Search

    Mounir Laroussi; Gary S. Sayler; Battle B. Glascock; Bruce McCurdy; Mary E. Pearce; Nathan G. Bright; Chad M. Malott

    1999-01-01

    Among the various industrial uses of the glow discharge at atmospheric pressure (GDAP), biological applications such as sterilization are under investigation. In this paper, we present images of a liquid medium (Luria-Bertani broth with tetracycline) contaminated by Escherichia coli bacteria (strain PER 322) undergoing plasma treatment. In most cases, it is found that an exposure time of two to 20

  1. Intensity distributions of spectral lines and elementary processes in a negative glow discharge column

    Microsoft Academic Search

    I. I. Murav'ev; G. S. Evtushenko; R. G. Karimov; V. S. Kurov

    1980-01-01

    The connection is established between the intensity distributions of the spectral lines along a negative glow discharge column and the individual elementary processes which take place in a low-temperature nonequilibrium plasma (direct electron excitation, step processes, recombination, collisions of the second kind, and charge exchange). The experiments were made in pure inert gases and mixtures of them at pressures 1

  2. Intensity distributions of spectral lines and elementary processes in a negative glow discharge column

    Microsoft Academic Search

    I. I. Murav'ev; G. S. Evtushenko; R. G. Karimov; V. S. Kurov

    1980-01-01

    The connection is established between the intensity distributions of the spectral lines along a negative glow discharge column and the individual elementary processes which take place in a low-temperature nonequilibrium plasma (direct electron excitation, step processes, recombination, collisions of the second kind, and charge exchange). The experiments were made in pure inert gases and mixtures of them at pressures 1–30

  3. One-Dimensional Fluid Simulation of Atmospheric-Pressure Helium DC Glow Discharges

    Microsoft Academic Search

    Akinori Oda; Takashi Kimura

    2009-01-01

    Atmospheric-pressure glow discharges (APGDs) have been widely used for material processing such as etching, deposition and surface modification and biomedical applications because of the material processing without thermal damage, discharge uniformity over the large area, and so on. In order to suitably utilize APGDs for these applications, further understanding of fundamental properties in APGDs is strongly required. In this paper,

  4. XI. Negative sections of the cold-cathode glow discharge in helium

    Microsoft Academic Search

    K. G. Emeléus; W. L. Brown; H. Mc N. Cowan

    1934-01-01

    An outline is presented of the results of the first part of an investigation of a cold-cathode low-voltage glow discharge in He at about 1 mm. pressure made chiefly by collector methods supplemented optically. Data so obtained are less exact than with discharge forms passing heavier currents, but represent an advance on older methods in enabling outstanding problems to be

  5. DC normal glow discharges in atmospheric pressure atomic and molecular gases

    Microsoft Academic Search

    David Staack; Bakhtier Farouk; Alexander Gutsol; Alexander Fridman

    2008-01-01

    DC glow discharges were experimentally investigated in atmospheric pressure helium, argon, hydrogen, nitrogen and air. The discharges were characterized by visualization of the discharges and voltage and current measurements for current of up to several milliamperes. Significant differences are seen in the gas temperature; however all the discharges appear to operate as temperature and pressure scaled versions of low pressure

  6. Experimental measurements on the current balance at the cathode of a cylindrical hollow cathode glow discharge

    Microsoft Academic Search

    H. Helm

    1979-01-01

    The contribution of positive ions, photons and metastable particles to the secondary emission of electrons from the cathode of an argon glow discharge with cylindrical cathode is measured by sampling the plasma species through a small orifice in the cathode wall and analyzing them in a high vacuum region. Additional experiments are made with a second apparatus which enables the

  7. Enhanced energy deposition efficiency of glow discharge electron beams for metal surface treatment

    Microsoft Academic Search

    Nélida Mingolo; Yanina Cesa; Oscar E. Martínez; Javier I. Etcheverry; Jorge J. Rocca

    2000-01-01

    The energy deposition efficiency and focal spot dynamics of electron beams produced by pulsed cold-cathode high-voltage glow discharges for metal surface treatment are investigated for two different cathode geometries. A concave cathode geometry in which the focusing is dominated by the convergence of the electric field lines in the cathode fall region is compared with flat cathode in which the

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

    Microsoft Academic Search

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

    2003-01-01

    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

  9. Shock-wave propagation in the plasma of a transverse glow discharge in argon

    Microsoft Academic Search

    I. V. Basargin; G. I. Mishin

    1985-01-01

    Shock waves traveling perpendicularly to a glow discharge in an Ar plasma and Ar with no plasma were observed experimentally to examine the dissipation of shock wave energy. A piezoelectric gage attached to a quartz rod furnished the pressure pulse data by which the shock velocities could be monitored at two points in the ambient medium. The shock wave propagated

  10. Shock wave propagation and dispersion in glow discharge plasmas Sergey O. Macheret,a)

    E-print Network

    Miles, Richard

    Shock wave propagation and dispersion in glow discharge plasmas Sergey O. Macheret,a) Yuri Z potentially have an impact on high-speed aerodynamics. Using plasmas for shock wave control, drag reduction have to be resolved prior to any practical ap- plications. The propagation of shock waves in weakly

  11. DC Discharge Studies Using PIC-MCC: Unmagnetized Glow Discharge Theory Jeff Hammel & John Verboncoeur

    E-print Network

    Wurtele, Jonathan

    DC Discharge Studies Using PIC-MCC: Unmagnetized Glow Discharge Theory Jeff Hammel & John. · M. A. Lieberman and A. J. Lichtenberg. Principles of Plasma Discharges and Material Processing. John in Gases. John Wiley and Sons, Inc., New York, 1939. · Yuri P. Raizer. Gas Discharge Physics. Springer

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

    NASA Astrophysics Data System (ADS)

    Reece Roth, J.

    2000-10-01

    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.

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

    ERIC Educational Resources Information Center

    Richardson, John M.

    2012-01-01

    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…

  14. Utilizing a one-atmosphere uniform glow discharge plasma for chemical\\/biological warfare agent decontamination

    Microsoft Academic Search

    M. R. McLean; J. R. Roth

    1998-01-01

    Summary form only given, as follows. An innovative approach to the decontamination of chemical and\\/or biological warfare agents is described. This recently developed technology involves utilizing a one atmosphere uniform glow discharge plasma (OAUGDP) as the decontaminant\\/sterilant. The plasma provides a very powerful but environmentally safe oxidizing and disinfecting technique without the use of strong chemicals (chlorine bleach) or high

  15. Emission spectral characteristics of Cu, Ag, Zn, and Cd neutral atoms in a glow discharge

    Microsoft Academic Search

    Yuhui Zhao; Gary Horlick

    2006-01-01

    Detailed spectra highlighting the neutral atom emission characteristics (i.e. I lines) for Cu, Zn, Ag and Cd in a glow discharge device are presented in this study. A particular focus is the presentation of spectra that document the many high excitation energy neutral atom lines that are observed in these spectra. For Cu, several spectral lines originating from levels close

  16. Oscillation modes of direct current microdischarges with parallel-plate geometry

    SciTech Connect

    Stefanovic, Ilija; Kuschel, Thomas; Winter, Joerg [Institut fuer Experimentalphysik II, Ruhr-Universitaet Bochum, 44781 Bochum (Germany); Skoro, Nikola; Maric, Dragana; Petrovic, Zoran Lj [Institute of Physics, University of Belgrade, POB 68, 11080 Belgrade (Serbia)

    2011-10-15

    Two different oscillation modes in microdischarge with parallel-plate geometry have been observed: relaxation oscillations with frequency range between 1.23 and 2.1 kHz and free-running oscillations with 7 kHz frequency. The oscillation modes are induced by increasing power supply voltage or discharge current. For a given power supply voltage, there is a spontaneous transition from one to other oscillation mode and vice versa. Before the transition from relaxation to free-running oscillations, the spontaneous increase of oscillation frequency of relaxation oscillations form 1.3 kHz to 2.1 kHz is measured. Fourier transform spectra of relaxation oscillations reveal chaotic behavior of microdischarges. Volt-ampere (V-A) characteristics associated with relaxation oscillations describes periodical transition between low current, diffuse discharge, and normal glow. However, free-running oscillations appear in subnormal glow only.

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

    NSDL National Science Digital Library

    Grinnell, Max

    2011-09-16

    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.

  18. Simulation Study on the Self-Sustained Oscillations in DC Driven Glow Discharges at Atmospheric Pressure Under Different Gas Gaps

    NASA Astrophysics Data System (ADS)

    Wang, Xiaofei; He, Yafeng; Liu, Fucheng

    2015-06-01

    In this paper, a one-dimensional plasma fluid model is employed to study the self-sustained oscillations in DC-driven helium glow discharges at atmospheric pressure under different gas gaps. Our simulation results indicate that a harmonic current oscillation with tiny amplitude always occur at the onset of instability and transits into a relaxation one as the conductivity of the semiconductor is decreased. It is found that the dynamics of the oscillations are dependent on the gas gaps. The discharge can only exhibit a simple oscillation with unique amplitude and frequency at smaller gas gaps (<2 mm) while it can exhibit a more complex oscillation with several different amplitudes and frequencies at larger gas gaps (>2 mm). The discharge modes in these current oscillations have also been analyzed. supported by National Natural Science Foundation of China (Nos. 11205044 and 11405042), Hebei Natural Science Fund of China (Nos. A2012201015 and A2011201006), the Research Foundation of Education Bureau of Hebei Province of China (No. Y2012009), the Postdoctoral Science Foundation of Hebei Province of China (No. B2014003004) and the Postdoctoral Foundation of Hebei University

  19. Chemical equilibria of rare earth oxides in glow-discharge mass spectrometry

    SciTech Connect

    Mei, Y.

    1992-01-01

    This research centers around method development and fundamental exploration of the rare earth elements (REE) in glow discharge mass spectrometry (GDMS). The capability of GDMS to analyze directly solids materials eliminates the sample dissolution and preconcentration steps required by many other methods. The simplicity of sample preparation and instrumental operation makes GDMS a promising analytical technique for the field of earth science. Initial studies were dedicated to improving the detection sensitivity of GDMS in analyzing the REE. This was accomplished by eliminating water contamination, a factor that was found to prevent the conversion of the rare earth oxidized to their atomic form in the glow discharge plasma. Methods experimented for water elimination included the uses of both a cryogenic cooling device and getter reagents. When used to determine the REE concentrations in a standard rock sample, the chemical elimination approach yielded comparable results to that obtained by other analytical methods. Further studies focused on probing the chemical reactions involving the REE and other plasma constituents in the glow discharge. It is proposed that the availability of the atomic REE in the glow discharge is strongly influenced by the oxidant and reductant contents in the plasma. Species that contain oxygen tend to shift the redox equilibria of REE toward the formation of their oxides, whereas species that compete for oxygen help reduce the oxidant content in the plasma, and shift the REE redox equilibria toward the formation of the REE atoms. Factors that govern the reaction processes of the REE equilibria were investigated by means of plasma reagent introduction and time-resolved discharge operation. Results indicate that while redox equilibria between the elemental REE and their monoxides exist on the cathode surface and in the gas phase, interactions occurring in the gas phase are probably the main paths for this equilibration in the glow discharge.

  20. Modelling of tokamak glow discharge cleaning II: comparison with experiment and application to ITER

    NASA Astrophysics Data System (ADS)

    Kogut, D.; Douai, D.; Hagelaar, G.; Pitts, R. A.

    2015-02-01

    The primary function of the ITER glow discharge cleaning (GDC) system will be the preparation of in-vessel component surfaces prior to the machine start-up. It may also contribute to tritium removal in the nuclear phase. In GDC, conditioning efficiency is strongly dependent on the homogeneity of the flux of ions impinging onto wall surfaces. In order to assess the wall particle flux distribution in ITER, a novel 2D multi-fluid model, described in a companion paper, has recently been developed and is benchmarked here against both experimental glow discharge data obtained in a small laboratory chamber with cylindrical geometry and from two large toroidal devices: the JET tokamak and the RFX reverse field pinch. In the laboratory plasma, simulated and measured plasma electron density and temperature are in a good agreement in the negative glow region, while discrepancies exist in the anode glow, where the fluid description of the model is inaccurate due to long mean free paths of electrons. Calculated and measured ion flux distribution profiles in RFX are found in good agreement, whereas in JET comparison it is more difficult, due to the complex geometry of the first wall which leads to local inhomogeneities in the measured flux. Simulations of H2-GDC for ITER with one or two anodes indicate fairly homogeneous plasma parameters and wall ion flux in the negative glow at 0.5?Pa, a commonly used gas pressure for GDC in existing fusion devices. Although the axisymmetric geometry in the model does not allow all seven ITER anodes to be powered simultaneously in the simulations, the results can be extrapolated to the full system and predict ion current densities on wall surfaces close to the simple expectation of total anode current divided by wall surface area (0.21?A?m?2), which is relevant to GDC in JET and other machines.

  1. Congenital Abnormalities and Multiple Sclerosis

    PubMed Central

    2010-01-01

    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. PMID:21080921

  2. [Phenomenology of abnormal body perceptions].

    PubMed

    Schäfer, M L

    1983-01-01

    The present paper deals with the problematic nature of the phenomenological grasping of the consciousness of the body and its pathological modifications. The reasoning is oriented by the doctrine of Husserl of the so-called sentiments as the fundamentals of the experience of the own body. This basic approach does not only seem to be basically for a psychology of the consciousness of the body, but also to give the theoretical-conceptual structure for a great number of psychopathological modifications. Subsequent to a criticism of the conventional use of the term 'hallucination of the body' we attempt to chart elements of a scheme of the abnormal consciousness of the body. PMID:6647887

  3. Theory and analysis of operating modes in microplasmas assisted by field emitting cathodesa)

    NASA Astrophysics Data System (ADS)

    Venkattraman, Ayyaswamy

    2015-05-01

    Motivated by the recent interest in the development of novel diamond-based cathodes, we study microplasmas assisted by field emitting cathodes with large field enhancement factors using a simplified model and comparisons with particle-in-cell with Monte Carlo collision (PIC-MCC) simulations and experiments. The model used to determine current-voltage characteristics assumes a linearly varying electric field in the sheath and predicts transition from an abnormal glow to arc mode at moderate current densities in a 1 mm argon gap. The influence of an external circuit is also considered to show the dependence of current as a function of the applied voltage, including potential drop across external resistors. PIC-MCC simulations confirm the validity of the model and also show the significant non-equilibrium nature of these low-temperature microplasmas with electron temperatures ˜1 eV and ion temperatures ˜ 0.07 eV in the quasi-neutral region. The model is also used to explain experimental data reported for a 1 mm argon gap at a pressure of 2 Torr using three different diamond-based cathodes with superior field emitting properties. The comparison shows that operating conditions in the experiments may not result in significant field emission and the differences observed in current-voltage characteristics can be attributed to small differences in the secondary electron emission coefficient of the three cathodes. However, the model and simulations clearly indicate that field emission using novel cathodes with high field enhancement factors can be used to enhance microplasmas by significantly decreasing the power requirements to achieve a given plasma number density even in gaps at which field emission is traditionally not considered to be a dominant mechanism.

  4. Abnormal fat distribution in PMM2-CDG.

    PubMed

    Wolthuis, D F G J; van Asbeck, E V; Kozicz, T; Morava, E

    2013-11-01

    We hypothesize that abnormal fat distribution, a common feature of PMM2-CDG, is associated with abnormal perinatal hormone regulation. We assessed 32 cases with PMM2-CDG, for the comorbidity of hypoglycemia/hyperinsulinism and fat pads. Ninety percent of patients with hypoketotic hypoglycemia and/or hyperinsulinism had abnormal fat distribution, while normoglycemic patients showed this feature in 50% of the cases. This statistically significant difference suggests an etiological role of the insulin receptor in developing abnormal fat distribution in PMM2-CDG. PMID:24063868

  5. Emission- and fluorescence-spectroscopic investigation of a glow discharge plasma: Absolute number density of radiative and nonradiative atoms in the negative glow

    NASA Astrophysics Data System (ADS)

    Takubo, Y.; Sato, T.; Asaoka, N.; Kusaka, K.; Akiyama, T.; Muroo, K.; Yamamoto, M.

    2008-01-01

    The excited-state atom densities in the negative glow of a direct-current glow discharge are derived from the spectral-line intensity of radiative atoms and the resonance-fluorescence photon flux of nonradiative atoms. The discharge is operated in a helium-argon gas mixture (molar fraction ratio 91:9; total gas pressure 5 Torr) at a dc current of 0.7-1.2 mA. The observations are made in the region of the maximum luminance in the cathode region, where high-energy electrons accelerated in the cathode fall are injected into the negative glow. The emission intensities of the He I, He II, Ar I, and Ar II spectral lines are measured with a calibrated tungsten ribbon lamp as an absolute spectral-radiance standard. Fluorescence photons scattered by helium and argon atoms in the metastable state and argon atoms in the resonance state are detected by the laser-induced fluorescence (LIF) method with the Rayleigh scattering of nitrogen molecules as an absolute standard of scattering cross section. The laser absorption method is incorporated to confirm the result of the LIF measurement. Excitation energies of the measured spectral lines range from 11.6 (Ar I) to 75.6 eV (He II), where the excitation energy is measured from the ground state of the neutral atom on the assumption that, in the plasma of this study, both the neutral and the ionic lines are excited by electron impact in a single-step process from the ground state of the corresponding neutral atoms. Experimental evidence is shown for the validity of this assumption.

  6. Emission- and fluorescence-spectroscopic investigation of a glow discharge plasma: absolute number density of radiative and nonradiative atoms in the negative glow.

    PubMed

    Takubo, Y; Sato, T; Asaoka, N; Kusaka, K; Akiyama, T; Muroo, K; Yamamoto, M

    2008-01-01

    The excited-state atom densities in the negative glow of a direct-current glow discharge are derived from the spectral-line intensity of radiative atoms and the resonance-fluorescence photon flux of nonradiative atoms. The discharge is operated in a helium-argon gas mixture (molar fraction ratio 91:9; total gas pressure 5 Torr) at a dc current of 0.7-1.2 mA. The observations are made in the region of the maximum luminance in the cathode region, where high-energy electrons accelerated in the cathode fall are injected into the negative glow. The emission intensities of the He I, He II, Ar I, and Ar II spectral lines are measured with a calibrated tungsten ribbon lamp as an absolute spectral-radiance standard. Fluorescence photons scattered by helium and argon atoms in the metastable state and argon atoms in the resonance state are detected by the laser-induced fluorescence (LIF) method with the Rayleigh scattering of nitrogen molecules as an absolute standard of scattering cross section. The laser absorption method is incorporated to confirm the result of the LIF measurement. Excitation energies of the measured spectral lines range from 11.6 (Ar I) to 75.6 eV (He II), where the excitation energy is measured from the ground state of the neutral atom on the assumption that, in the plasma of this study, both the neutral and the ionic lines are excited by electron impact in a single-step process from the ground state of the corresponding neutral atoms. Experimental evidence is shown for the validity of this assumption. PMID:18351942

  7. Sampling modulation technique in radio-frequency helium glow discharge emission source by use of pulsed laser ablation

    Microsoft Academic Search

    TariqMahmood Naeem; Hideyuki Matsuta; Kazuaki Wagatsuma

    2004-01-01

    An emission excitation source comprising a high-frequency diode-pumped Q-switched Nd:YAG laser and a radio-frequency powered glow discharge lamp is proposed. In this system sample atoms ablated by the laser irradiation are introduced into the lamp chamber and subsequently excited by the helium glow discharge plasma. The pulsed operation of the laser can produce a cyclic variation in the emission intensities

  8. Development and fundamental investigation of Laser Ablation Glow Discharge Time-Of-Flight Mass Spectrometry (LA-GD-TOFMS)

    Microsoft Academic Search

    Mohamed Tarik; Giovanni Lotito; James A. Whitby; Joachim Koch; Katrin Fuhrer; Marc Gonin; Johann Michler; Jean-Luc Bolli; Detlef Günther

    2009-01-01

    Glow Discharge (GD) spectroscopy is a well known and accepted technique for the bulk and surface composition analysis, while laser ablation (LA) provides analysis with high spatial-resolution analysis in LIBS (laser-induced breakdown spectroscopy) or when coupled to inductively coupled plasma spectrometry (ICP-OES or ICP-MS). This work concerns the construction of a Laser Ablation Glow Discharge Time-Of-Flight Mass Spectrometry (LA-GD-TOFMS) instrument

  9. Modeling the effect of the cathode geometry in a DC glow discharge ion source for mass spectrometry

    Microsoft Academic Search

    A. Fiala; L. C. Pitchford; J. P. Boeuf; S. Baude

    1997-01-01

    A self-consistent, two-dimensional hybrid fluid-particle model is used to study the effect of cathode geometry on the plasma produced in an argon glow discharge for conditions typically of the commercially available glow discharge mass spectrometer system (VG9000 spectrometer and Megacell source). For a given power supply voltage and gas pressure, we show that the spatial distribution of the plasma in

  10. The effect of rare earth doping on the glow peak positions of LiNaSO 4

    Microsoft Academic Search

    M. Maghrabi; D.-E. Arafah; L. Barham; M. Olaimi

    2007-01-01

    Thermoluminescence of the rare earths (Ho, Tb, Gd, Sm, Ce or La) doped LiNaSO4 and irradiated at room temperature was studied in the temperature range 300–673K. The glow curves of this material consistently illustrate the presence of two groups of glow peaks that behave differently. The first group occurs in the temperature range 350–450K, and the individual peaks occur at

  11. The influence of longitudinal magnetic field on recombination radiation of low-pressure glow discharge in hydrogen and helium

    Microsoft Academic Search

    I. M. Ulanov; A. Yu. Litvintsev; V. A. Pinaev

    2011-01-01

    We study the influence of longitudinal magnetic field on the radiation of low-pressure glow discharges in hydrogen and helium.\\u000a We conducted experiments under a pressure in a discharge chamber of 10–20 Pa and a discharge current of 10–20 mA. A 0–1600\\u000a G magnetic field influenced only the cathode parts of the discharge, negative glow, and the dark Faraday space. The

  12. CrN–TiN multilayer coating on magnesium alloy AZ91 by arc-glow plasma depositing process

    Microsoft Academic Search

    Q. Miao; C. E. Cui; J. D. Pan

    2007-01-01

    CrN–TiN multilayer films were deposited on magnesium alloy AZ91 by a novel method of arc-glow plasma depositing to improve its wear resistance. The total thickness of the coating was about 2 ?m with 12 sub-layers of CrN and TiN deposited alternately.The composition and microstructure of the coating layer were analyzed by means of X-ray diffraction (XRD) and glow discharge spectrum (GDS).

  13. High-Voltage, glow-discharge electron sources and possibilities of its application in industry for realizing different technological operations

    Microsoft Academic Search

    Stanislav V. Denbnovetsky; Vitaliy G. Melnyk; Igor V. Melnyk

    2003-01-01

    Important problems of generation and forming electron beams in electrode systems of a high-voltage glow discharge are discussed. Also considered are dependencies of energetic parameters on the formed electron beam as well as on anode plasma parameters from the discharge voltage and current. Examples are given of some up-to-date and advanced possibilities of using high-voltage, glow-discharge electron beam sources for

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

    Microsoft Academic Search

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

    2006-01-01

    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

  15. Transitions between corona, glow, and spark regimes of nanosecond repetitively pulsed discharges in air at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Pai, David Z.; Lacoste, Deanna A.; Laux, Christophe O.

    2010-05-01

    In atmospheric pressure air preheated from 300 to 1000 K, the nanosecond repetitively pulsed (NRP) method has been used to generate corona, glow, and spark discharges. Experiments have been performed to determine the parameter space (applied voltage, pulse repetition frequency, ambient gas temperature, and interelectrode gap distance) of each discharge regime. In particular, the experimental conditions necessary for the glow regime of NRP discharges have been determined, with the notable result that there exists a minimum and maximum gap distance for its existence at a given ambient gas temperature. The minimum gap distance increases with decreasing gas temperature, whereas the maximum does not vary appreciably. To explain the experimental results, an analytical model is developed to explain the corona-to-glow (C-G) and glow-to-spark (G-S) transitions. The C-G transition is analyzed in terms of the avalanche-to-streamer transition and the breakdown field during the conduction phase following the establishment of a conducting channel across the discharge gap. The G-S transition is determined by the thermal ionization instability, and we show analytically that this transition occurs at a certain reduced electric field for the NRP discharges studied here. This model shows that the electrode geometry plays an important role in the existence of the NRP glow regime at a given gas temperature. We derive a criterion for the existence of the NRP glow regime as a function of the ambient gas temperature, pulse repetition frequency, electrode radius of curvature, and interelectrode gap distance.

  16. Semen abnormalities with SSRI antidepressants.

    PubMed

    2015-01-01

    Despite decades of widespread use, the adverse effect profile of "selective" serotonin reuptake inhibitor (SSRI) antidepressants has still not been fully elucidated. Studies in male animals have shown delayed sexual development and reduced fertility. Three prospective cohort studies conducted in over one hundred patients exposed to an SSRI for periods ranging from 5 weeks to 24 months found altered semen param-eters after as little as 3 months of exposure: reduced sperm concentration, reduced sperm motility, a higher percentage of abnormal spermatozoa, and increased levels of sperm DNA fragmentation. One clinical trial showed growth retardation in children considered depressed who were exposed to SSRls. SSRls may have endocrine disrupting properties. Dapoxetine is a short-acting serotonin reuptake inhibitor that is chemically related to fluoxetine and marketed in the European Union for men complaining of premature ejaculation. But the corresponding European summary of product characteristics does not mention any effects on fertility. In practice, based on the data available as of mid-2014, the effects of SSRI exposure on male fertility are unclear. However, it is a risk that should be taken into account and pointed out to male patients who would like to father a child or who are experiencing fertility problems. PMID:25729824

  17. Biochemical abnormalities in Pearson syndrome.

    PubMed

    Crippa, Beatrice Letizia; Leon, Eyby; Calhoun, Amy; Lowichik, Amy; Pasquali, Marzia; Longo, Nicola

    2015-03-01

    Pearson marrow-pancreas syndrome is a multisystem mitochondrial disorder characterized by bone marrow failure and pancreatic insufficiency. Children who survive the severe bone marrow dysfunction in childhood develop Kearns-Sayre syndrome later in life. Here we report on four new cases with this condition and define their biochemical abnormalities. Three out of four patients presented with failure to thrive, with most of them having normal development and head size. All patients had evidence of bone marrow involvement that spontaneously improved in three out of four patients. Unique findings in our patients were acute pancreatitis (one out of four), renal Fanconi syndrome (present in all patients, but symptomatic only in one), and an unusual organic aciduria with 3-hydroxyisobutyric aciduria in one patient. Biochemical analysis indicated low levels of plasma citrulline and arginine, despite low-normal ammonia levels. Regression analysis indicated a significant correlation between each intermediate of the urea cycle and the next, except between ornithine and citrulline. This suggested that the reaction catalyzed by ornithine transcarbamylase (that converts ornithine to citrulline) might not be very efficient in patients with Pearson syndrome. In view of low-normal ammonia levels, we hypothesize that ammonia and carbamylphosphate could be diverted from the urea cycle to the synthesis of nucleotides in patients with Pearson syndrome and possibly other mitochondrial disorders. PMID:25691415

  18. Hereditary evaluation of multiple developmental abnormalities in the Havanese dog breed.

    PubMed

    Starr, Alison N; Famula, Thomas R; Markward, Nathan J; Baldwin, Joanne V; Fowler, Karon D; Klumb, Diane E; Simpson, Nancy L; Murphy, Keith E

    2007-01-01

    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

  19. Estimation of electron temperature in transient glow discharge using ionization wave

    SciTech Connect

    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

    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.

  20. Plasma Treatment of Polyethylene Powder Particles in Hollow Cathode Glow Discharge

    SciTech Connect

    Wolter, Matthias; Quitzau, Meike; Bornholdt, Sven; Kersten, Holger [IEAP, University Kiel, Kiel (Germany)

    2008-09-07

    Polyethylen (PE) is widely used in the production of foils, insulators, packaging materials, plastic bottles etc. Untreated PE is hydrophobic due to its unpolar surface. Therefore, it is hard to print or glue PE and the surface has to be modified before converting.In the present experiments a hollow cathode glow discharge is used as plasma source which is mounted in a spiral conveyor in order to ensure a combines transport of PE powder particles. With this set-up a homogeneous surface treatment of the powder is possible while passing the glow discharge. The plasma treatment causes a remarkable enhancement of the hydrophilicity of the PE powder which can be verified by contact angle measurements and X-ray photoelectron spectroscopy.

  1. Hollow cathode glow discharge ring laser block and electrode structure for ring laser angular rate sensors

    SciTech Connect

    Lind, B.J.

    1989-09-05

    This patent describes a ring laser. It comprises: a gas impervious block containing at least three tunnels meeting to form, at least in part, a closed-loop gas containing cavity; electromagnetic wave reflecting surfaces for reflecting a pair of counter-propagating electromagnetic waves to propagate along the closed-loop cavity substantially defined by the tunnels; a gas contained within the closed-loop cavity; a first electrode; a second electrode; the first and second electrodes positioned relative to each other to support a discharge current through the gas and establish a glow discharge region therebetween to induce a pair of counter-propagating laser beams to propagate through the glow discharge region in a direction transverse to the direction of the discharge current.

  2. Atomic iodine production in a gas flow by decomposing methyl iodide in a dc glow discharge

    SciTech Connect

    Mikheyev, P A; Shepelenko, A A; Voronov, A I; Kupryaev, Nikolai V [Samara Branch of the P.N. Lebedev Physics Institute, Russian Academy of Sciences, Samara (Russian Federation)

    2002-01-31

    The production of atomic iodine for an oxygen - iodine laser is studied by decomposing methyl iodide in a dc glow discharge in a vortex gas flow. The concentration of iodine atoms in discharge products was measured from the atomic iodine absorption of the radiation of a single-frequency tunable diode laser at a wavelength of 1.315 {mu}m. Atomic iodine concentrations sufficient for the operation of an oxygen - iodine laser were obtained. The concentration of atomic iodine amounted to 3.6 x 10{sup 15} cm{sup -3} for a pressure of the carrying argon gas of 15 Torr. The discharge stabilisation by a vortex gas flow allowed the glow discharge to be sustained in a strongly electronegative halogen-containing gas mixture for pressures up to 20 Torr. (active media)

  3. Glow-discharge-assisted laser-induced breakdown spectroscopy: increased sensitivity in solid analysis.

    PubMed

    Tereszchuk, K A; Vadillo, J M; Laserna, J J

    2008-11-01

    A glow discharge operating in steady-state and pulsed temporal conditions is used to excite the material previously excited by a pulsed laser ablation system. The system provides a simple means by which to potentially excite the material ablated by the incident laser pulse by taking advantage of enhanced collisional excitation. In this way, one can effectively reduce laser pulse energies below the excitation and ionization thresholds to potentially those required solely for laser ablation of the material, reducing sample damage and improving the lateral resolution. Several critical parameters such as the gas pressure, gas type, and discharge voltage were evaluated, demonstrating the potential of the technique for spatially resolved analysis. The new dual glow-discharge laser-induced breakdown spectroscopy (GD-LIBS) synchronous scheme provides significant signal enhancements when compared to LIBS or GD under identical conditions. PMID:19007470

  4. Theoretical characterization of an atmospheric pressure glow discharge used for analytical spectrometry.

    PubMed

    Martens, Tom; Mihailova, Diana; van Dijk, Jan; Bogaerts, Annemie

    2009-11-01

    We have investigated the plasma processes in an atmospheric pressure glow discharge (APGD) in He used for analytical spectrometry by means of fluid and Monte Carlo (MC) simulations. Typical results include the potential and electric field distributions in the plasma, the density profiles of the various plasma species throughout the discharge, the mean electron energy, as well as the rates of the various collision processes in the plasma, and the relative importance of the different production and loss rates for the various species. The similarities and differences with low-pressure glow discharges are discussed. The main differences are a very small cathode dark space region and a large positive column as well as the dominant role of molecular ions. Some characteristic features of the APGD, such as the occurrence of the different spatial zones in the discharge, are illustrated, with links to experimental observations. PMID:19813757

  5. Influence of the Walls on the Formation of a DC Glow Discharge

    NASA Astrophysics Data System (ADS)

    Demidov, Vladimir; Bogdanov, Yevgeny; Adams, Steve; Kudryavtsev, Anatoly

    2009-10-01

    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.

  6. The impact of light source spectral power distribution on sky glow

    NASA Astrophysics Data System (ADS)

    Luginbuhl, Christian B.; Boley, Paul A.; Davis, Donald R.

    2014-05-01

    The effect of light source spectral power distribution on the visual brightness of anthropogenic sky glow is described. Under visual adaptation levels relevant to observing the night sky, namely with dark-adapted (scotopic) vision, blue-rich (“white”) sources produce a dramatically greater sky brightness than yellow-rich sources. High correlated color temperature LEDs and metal halide sources produce a visual brightness up to 8× brighter than low-pressure sodium and 3× brighter than high-pressure sodium when matched lumen-for-lumen and observed nearby. Though the sky brightness arising from blue-rich sources decreases more strongly with distance, the visual sky glow resulting from such sources remains significantly brighter than from yellow sources out to the limits of this study at 300 km.

  7. Glow Discharge Mass Spectrometry Analysis of LX-17 and PBX-9502 High Explosive Samples

    SciTech Connect

    Nilsen, J; Castor, J I; Lane, M A; Overturf, G E

    2002-12-16

    As part of the Campaign 4 effort in A Division we have done an analysis of several high explosives that are used in the current nuclear stockpile. In particular we have looked at samples of LX-17 and PBX-9502. The analysis was done using the glow discharge mass spectrometer that is currently located in B132N and operated by Mark Lane of the Chemistry and Material Science (CMS) Directorate. George Overturf from CMS obtained small samples of high explosive for the measurements. From the analysis we wanted to verify the actual atomic composition of the high explosive, see how that compared with the nominal composition, and understand whether any significant impurities existed in the samples. We present the analysis of several LX-17 and PBX-9502 samples using the glow discharge mass spectrometer to measure both the main constituents of the high explosive as well as any trace materials that may be present.

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

    SciTech Connect

    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

    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.

  9. Surface modification of PDMS using atmospheric glow discharge polymerization of tetrafluoroethane for immobilization of biomolecules

    NASA Astrophysics Data System (ADS)

    Anand, V.; Ghosh, S.; Ghosh, M.; Rao, G. M.; Railkar, R.; Dighe, R. R.

    2011-08-01

    In this study an atmospheric glow discharge with a fluorocarbon gas as precursor was used to modify the surface of polydimethyl siloxane (PDMS -[(CH 3) 2SiO] n-). The variation in protein immobilizing capability of PDMS was studied for different times of exposure. It was observed that the concentration of proteins adsorbed on the surface varied in an irregular manner with treatment time. The fluorination results in the formation of a thin film of fluorocarbon on the PDMS surface. The AFM and XPS data suggest that the film cracks due to stress and regains its uniformity thereafter. This Stranski-Krastanov growth model of the film was due to the high growth rate offered by atmospheric glow discharge.

  10. Abnormal Web Usage Control by Proxy Strategies.

    ERIC Educational Resources Information Center

    Yu, Hsiang-Fu; Tseng, Li-Ming

    2002-01-01

    Approaches to designing a proxy server with Web usage control and to making the proxy server effective on local area networks are proposed to prevent abnormal Web access and to prioritize Web usage. A system is implemented to demonstrate the approaches. The implementation reveals that the proposed approaches are effective, such that the abnormal

  11. Immune Abnormalities in Patients with Autism.

    ERIC Educational Resources Information Center

    Warren, Reed P.; And Others

    1986-01-01

    A study of 31 autistic patients (3-28 years old) has revealed several immune-system abnormalities, including decreased numbers of T lymphocytes and an altered ratio of helper-to-suppressor T cells. Immune-system abnormalities may be directly related to underlying biologic processes of autism or an indirect reflection of the actual pathologic…

  12. Renal abnormalities and their developmental origin

    Microsoft Academic Search

    Andreas Schedl

    2007-01-01

    Congenital abnormalities of the kidney and urinary tract (CAKUT) occur in 1 out of 500 newborns, and constitute approximately 20–30% of all anomalies identified in the prenatal period. CAKUT has a major role in renal failure, and there is increasing evidence that certain abnormalities predispose to the development of hypertension and cardiovascular disease in adult life. Moreover, defects in nephron

  13. Pathophysiology of Cancer: Hormonal and Metabolic Abnormalities

    Microsoft Academic Search

    David Heber; N. S. Tchekmedyian

    1992-01-01

    Despite the development of advanced nutritional support technology, malnutrition remains a significant morbid and mortal complication of cancer. A number of metabolic abnormalities have been demonstrated in malnourished cancer patients, including increased protein breakdown, increased glucose production, increased lipolysis, hypogonadism in male patients, and insulin resistance. Previous studies conducted under metabolic ward conditions have demonstrated that metabolic abnormalities interfere with

  14. Dark Immunofluorescence: Correlation with Serum Immunoglobulin Abnormalities?

    PubMed Central

    List, J.; Buckland, M. S.; Thobhani, B.; Sheed, C. J.; Mann, J. C.; Claxton, M.; Heelan, B.

    2006-01-01

    Occasional serum samples (<0.5%) tested by indirect immunofluorescence showed less fluorescence than did negative-control serum. A retrospective review of these patients' serum immunoglobulins revealed a high percentage of abnormalities (71%, versus 22% of controls). We suggest that this observation should be reported when seen and that the clinician should be alerted to an association with immunoglobulin abnormalities. PMID:16971516

  15. An Abnormal Psychology Community Based Interview Assignment

    ERIC Educational Resources Information Center

    White, Geoffry D.

    1977-01-01

    A course option in abnormal psychology involves students in interviewing and observing the activities of individuals in the off-campus community who are concerned with some aspect of abnormal psychology. The technique generates student interest in the field when they interview people about topics such as drug abuse, transsexualism, and abuse of…

  16. Sonographically detected abnormalities of the umbilical cord

    Microsoft Academic Search

    T. D. Shipp; B. Bromley; B. R. Benacerraf

    1995-01-01

    Objectives: This study was undertaken as a retrospective chart review to evaluate the range of umbilical cord abnormalities detected by prenatal sonography, as well as the outcome and pathologic correlation. Methods: We identified 13 cases of umbilical cord abnormalities detected sonographically over a 46-month period. We evaluated the ultrasound appearance, size, location, and color Doppler characteristic in each case. Results:

  17. Unsupervised Abnormality Detection in Video Surveillance

    Microsoft Academic Search

    Takuya Nanri; Nobuyuki Otsu

    2005-01-01

    The detection of abnormal movements is an important prob- lem in video surveillance applications. We propose an unsupervised method for abnormal movement detection in scenes containing multiple persons. Our method uses cu- bic higher-order local auto-correlation (CHLAC) to extract movement features. We show that the additive property of CHLAC in combination with a linear subspace method is well suited to

  18. Detecting electrocardiogram abnormalities with independent component analysis

    E-print Network

    Noel, Steven

    detection of abnormal conditions in the heart. Unsupervised ICA neural networks can demix the components of measured ECG signals. Such components may correspond to individual heart functions, either normal for diagnosis well in advance of the actual onset of heart attack, in which abnormalities in the original

  19. Retinal Circulatory Abnormalities in Type 1 Diabetes

    Microsoft Academic Search

    Gilbert T. Feke; Sheldon M. Buzney; Hironobu Ogasawara; Naoki Fujio; Douglas G. Goger; Norman P. Spack; Kenneth H. GabbayX

    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

  20. Multiparametric tissue abnormality characterization using manifold regularization

    NASA Astrophysics Data System (ADS)

    Batmanghelich, Kayhan; Wu, Xiaoying; Zacharaki, Evangelia; Markowitz, Clyde E.; Davatzikos, Christos; Verma, Ragini

    2008-03-01

    Tissue abnormality characterization is a generalized segmentation problem which aims at determining a continuous score that can be assigned to the tissue which characterizes the extent of tissue deterioration, with completely healthy tissue being one end of the spectrum and fully abnormal tissue such as lesions, being on the other end. Our method is based on the assumptions that there is some tissue that is neither fully healthy or nor completely abnormal but lies in between the two in terms of abnormality; and that the voxel-wise score of tissue abnormality lies on a spatially and temporally smooth manifold of abnormality. Unlike in a pure classification problem which associates an independent label with each voxel without considering correlation with neighbors, or an absolute clustering problem which does not consider a priori knowledge of tissue type, we assume that diseased and healthy tissue lie on a manifold that encompasses the healthy tissue and diseased tissue, stretching from one to the other. We propose a semi-supervised method for determining such as abnormality manifold, using multi-parametric features incorporated into a support vector machine framework in combination with manifold regularization. We apply the framework towards the characterization of tissue abnormality to brains of multiple sclerosis patients.

  1. Ovarian dysgenesis in individuals with chromosomal abnormalities

    Microsoft Academic Search

    Christopher Cunniff; Kenneth Lyons Jones; Kurt Benirschke

    1991-01-01

    To understand better the pathogenesis of ovarian dysgenesis in individuals with abnormalities such as 45,X Turner syndrome, trisomy 13, and trisomy 18, we have examined microscopically the ovaries of 36 infants with a number of chromosomal abnormalities confirmed by karyotype analysis. All infants with trisomy 13, trisomy 18, triploidy, and 45,X were found to have severe ovarian dysgenesis characterized by

  2. Instability of a 550Base Pair DNA Segment and Abnormal Methylation in Fragile X Syndrome

    Microsoft Academic Search

    I. Oberle; F. Rousseau; D. Heitz; C. Kretz; D. Devys; A. Hanauer; J. Boue; M. F. Bertheas; J. L. Mandel

    1991-01-01

    The fragile X syndrome, a common cause of inherited mental retardation, is characterized by an unusual mode of inheritance. Phenotypic expression has been linked to abnormal cytosine methylation of a single CpG island, at or very near the fragile site. Probes adjacent to this island detected very localized DNA rearrangements that consti- tuted the fragile X mutations, and whose target

  3. An ion-neutral species collision model for particle simulation of glow discharge

    Microsoft Academic Search

    K. Nanbu; Y. Kitatani

    1995-01-01

    An ion-neutral species collision model with charge exchange is developed for use in particle simulation of a glow discharge based on an extension of the theory of Langevin (1905) and Hasse (1926). The validity of the model is checked by Monte Carlo calculation of drift velocity for He+-He, Ne+-Ne, Ar+-Ar and Kr+-Kr collisions. The results show good agreement with the

  4. Isotope ratio measurements by secondary ion mass spectrometry (SIMS) and glow discharge mass spectrometry (GDMS)

    NASA Astrophysics Data System (ADS)

    Betti, Maria

    2005-04-01

    The basic principles of secondary ion mass spectrometry and glow discharge mass spectrometry have been shortly revisited. The applications of both techniques as exploited for the isotope ratio measurements in several matrices have been reviewed. Emphasis has been given to research fields in expansions such as solar system studies, medicine, biology, environment and nuclear forensic. The characteristics of the two techniques are discussed in terms of sensitivity and methodology of quantification. Considerations on the different detection possibilities in SIMS are also presented.

  5. Nanometric powder of stoichiometric silicon carbide produced in square-wave modulated RF glow discharges

    Microsoft Academic Search

    G Viera; S. N Sharma; J. L újar; R. Q Zhang; J Costa; E Bertran

    1999-01-01

    SiC nanometric powder has been obtained in square-wave modulated radiofrequency glow discharges from CH4 and SiH4 gas mixtures. Chemical and structural characterization revealed that the as-deposited SiC:H powder underwent spontaneous oxidation when exposed to atmosphere. To stabilise the powder chemically, we carried out a thermal treatment under vacuum (10?4Pa) consisting of heating to 800°C (20°C\\/min). The effects on the structure

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

    Microsoft Academic Search

    Ion Radu; Ray Bartnikas; Michael R. Wertheimer

    2003-01-01

    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

  7. Analytic investigation of the anode zone of a higher-pressure glow discharge

    Microsoft Academic Search

    R. Sh. Ismalov

    1994-01-01

    The structure of the glow-discharge anode sheath is investigated analytically in the one-dimensional formulation within the\\u000a framework of a diffusion-drift approximation. Charged particle recombination reduces significantly the anode potential drop\\u000a and the width of the anode zone. Given fairly heavy current, which is typical of anode spots, the contribution of the diffusion\\u000a processes becomes significant because of the reduced width

  8. Analytic model of the cathode region of a short glow discharge in light gases

    Microsoft Academic Search

    V. I. Kolobov; L. D. Tsendin

    1992-01-01

    A self-consistent analytic model of the cathode region of a dc glow discharge is suggested. The description is based on the division of the discharge gap into a space-charge sheath and a plasma region and on an approximate kinetic analysis of different groups of electrons. A one-dimensional short discharge is considered for which the positive column is absent and the

  9. Optical Transmission Measurements on Glow-Discharge Amorphous Silicon Nitride Films

    NASA Astrophysics Data System (ADS)

    Ay, Ýlker; Tolunay, Hüseyýn

    2001-05-01

    Hydrogenated amorphous silicon nitride films have been prepared by the glow-discharge decomposition of ammonia/silane gas mixture. From optical transmission measurements in the wavelength range from 400 nm to 1100 nm refractive indices absorption coefficients and optical Tauc gaps of the films have been obtained. A systematic investigation of optical parameters has been carried out as a function of the nitrogen content of samples.

  10. Glow Worms as a Tourist Attraction in Springbrook National Park: Visitor Attitudes and Economic Issues

    Microsoft Academic Search

    Clevo Wilson; Clement A. Tisdell; David Merritt

    2004-01-01

    Insect-based tourism mainly caters to a niche market, but its popularity has been growing in recent years. Despite its popularity this form of tourism has remained under-researched and in a sense its contribution to the tourism industry has gone mostly unnoticed. This paper reports the results of a study undertaken on one form of popular insect-based tourism, namely glow worms.

  11. Electric field measurements in an argon glow discharge using laser spectroscopy

    Microsoft Academic Search

    Y. W. Choi; M. D. Bowden; K. Muraoka

    1996-01-01

    Direct measurements of the electric field in the sheath of a dc glow discharge were made using laser spectroscopic measurements of argon atoms. The effect of the electric field on the 4s?7f transitions was used to determine the electric field. Both laser opto-galvanic spectra and laser-induced fluorescence spectra were obtained. The magnitude of the electric field was determined using an

  12. Laser-induced plasma perturbation studies of energy transfer in CO2 glow-discharge lasers

    Microsoft Academic Search

    M. C. Gower; A. I. Carswell

    1974-01-01

    V-V and V-T energy transfer mechanisms have been investigated in CO2 glow discharges using a pulsed laser plasma perturbation method. The appropriate rate equations are presented, the solutions of which were found to adequately describe the observed induced spontaneous emission and discharge current changes. From the spontaneous emission studies, it is possible to observe directly intermolecular V-V pumping between CO2(nu3)

  13. Study of laser resonance ionization mass spectrometry using a glow discharge source

    SciTech Connect

    Xiong, X. [National Institute of Standards and Technology, Gaithersburg, Maryland (United States)]|[Eastern Analytical, Inc., 335 Paint Branch Dr., College Park, Maryland (United States); Hutchinson, J.M.R.; Fassett, J.D.; Lucatorto, T.B.; Schima, F.J.; Bowman, W.A. [National Institute of Standards and Technology, Gaithersburg, Maryland (United States); Hess, K.R. [Department of Chemistry, Franklin and Marshall College, Lancaster, Pennsylvania (United States)

    1995-04-01

    The mass spectra of a metal alloy sample consisting of Al, Cu and Fe were studied using both glow discharge mass spectrometry (GDMS) and resonance ionization mass spectrometry (RIMS). Particular emphasis was placed on the reduction of isobaric interferences and discrimination between those ions formed by the discharge and those formed by the laser radiation. {copyright} 1995 {ital American} {ital Institute} {ital of} {ital Physics}

  14. Excimer-laser-assisted RF glow-discharge deposition of amorphous and microcrystalline silicon thin films

    Microsoft Academic Search

    N. Layadi; P. Roca i Cabarrocas; M. Gerri; W. Marine; J. Spousta

    1994-01-01

    We combine the deposition of Hydrogenated amorphous Silicon (a-Si:H) by rf glow discharge with XeCl-excimer laser irradiation of the growing surface in order to obtain different kinds of silicon films in the same deposition system. In-situ UV-visible ellipsometry allows us to measure the optical properties of the films as the laser fluence is increased from 0 up to 180 mJ\\/cm2

  15. Influences of floating particles on high-pressure, pulsed glow discharge for excimer laser excitation

    Microsoft Academic Search

    G. Imada; T. Shinkai; W. Masuda; K. Yatsui

    2000-01-01

    The floating particles produced by the high-pressure, pulsed glow discharge on KrF excimer laser excitation have been visualized by the pulsed-laser scatter method. The double-pulse discharge experiments have also been carried out to study the effects of the floating particles on the discharge instabilities. The particles with diameter of the order of 100 µm are observed in the discharge region

  16. Isotopic analysis of uranium using glow discharge optogalvanic spectroscopy and diode lasers

    Microsoft Academic Search

    C. M. Barshick; R. W. Shaw; J. P. Young; J. M. Ramsey

    1994-01-01

    A hollow cathode glow discharge has been coupled with tunable lasers for isotopically selective excitation of gaseous uranium atoms produced by cathodic sputtering. A CW argon ion laser-pumped titanium:sapphire ring laser and a semiconductor diode laser were employed. Optogalvanic detection of the discharge atom population allowed identification of [sup 235]U at depleted, natural, and enriched abundances in uranium metal and

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

    Microsoft Academic Search

    Xiaohui Yuan; Laxminarayan L. Raja

    2003-01-01

    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

  18. A Miniature Glow Discharge for Laser Excited Atomic Fluorescence Detection of Lead

    Microsoft Academic Search

    C. L. Davis; B. W. Smith; J. D. Winefordner

    1995-01-01

    A miniature glow discharge atom reservoir has been designed for laser excited atomic fluorescence spectrometric measurements of nanoliter-sized solution residues. A copper vapor laser pumped dye laser was used to measure the fluorescence of Ph atoms sputtered from the Ni cathode of the discharge. Excitation of Pb occurred at 283.3 nm, and fluorescence was monitored at 405.8 nm. The optimal

  19. Comparative Study of Electric Field Measurement in Glow Discharges using Laser Optogalvanic Spectroscopy

    Microsoft Academic Search

    Shahid Hussain; M. Saleem; M. A. Baig

    2008-01-01

    The net electric field inside low-pressure glow discharges has been measured using laser optogalvanic spectroscopy of 1s2s 1S0-->np1P1 Rydberg series of atomic helium. Three different types of discharges, an inductively coupled RF discharge cell operating at 4 MHz, a homemade DC discharge cell and a commercial see-through hollow cathode lamp have been used for these studies. The Rydberg series terminates

  20. [New design of Grimm-type glow discharge source for real-time sputtered depth measurement].

    PubMed

    Wan, Zhen-Zhen; Li, Xiao-Jia; Wang, Yong-Qing; Sun, Rong-Xia; Shi, Ning

    2011-04-01

    The crater depth value of sample surface during sputtering is important analysis information for the depth profile analysis of glow discharge spectrometry. Real-time sputtered depth measurement with Laser triangulation measurement method for glow discharge compositional analysis, effectively solves the issues of incorrect depth value calculation and complicated procedures in traditional depth analysis method. This paper presents a new Grimm-type glow discharge source for real-time sputtering depth measurement by laser displacement sensor. This GD source also ensures fine sputtering effects and ideal resolution for multi-layer structure and interface. Optical fiber is used to transmit glow spectrum signal from GD-source to multi-channel photoelectric detection system. The design for the first time accomplishes the real-time signal collection and time-based synchronization analysis for both spectrum signal and sputtering depth signal. The real-time sputtering depth measurement curve of standard samples is obtained. The design and operating principle of this new-type GD-source is described in detail. Under the sputtering conditions of 30 mA, 900 V and 20 minutes, the sputtering rates of iron-based and copper-based sample sputtered by this GD source with good depth resolution are about 10 and 55 nm x s(-1). Surface topography picture of sputtering crater and microphotograph of metal samples are provided in the paper. Low-alloy steel standard sample is tested with this new GD source, the relative standard deviation (RSD) of C, Cu, Al, Ni, Mo, Mn and V elements are less than 1.7%, while for Cr and Si elements RSDs are less than 2.6%. The result data of the testing is provided in this paper. PMID:21714279

  1. Influences of Floating Particles Produced by High-Pressure, Pulsed Glow Discharge on Excimer Laser Excitation

    Microsoft Academic Search

    Go Imada; Takahiro Shinkai; Wataru Masuda; Kiyoshi Yatsui

    2001-01-01

    The floating particles produced by the high-pressure, pulsed glow discharge on KrF excimer laser excitation have been visualized by the pulsed-laser scatter method. The double-pulse discharge experiments have also been carried out to study the effects of the floating particles on the discharge instabilities. The particles with diameters of the order of 100 mum are observed in the discharge region

  2. Atmospheric pressure glow discharge desorption mass spectrometry for rapid screening of pesticides in food

    Microsoft Academic Search

    Matthias Conradin Jecklin; Gerardo Gamez; David Touboul; Renato Zenobi

    2008-01-01

    Flowing afterglow atmospheric pressure glow discharge tandem mass spectrometry (APGD-MS\\/MS) is used for the analysis of trace amounts of pesticides in fruit juices and on fruit peel. The APGD source was rebuilt after Andradeet al. (Andradeetal.,Anal.Chem. 2008; 80: 2646-2653; 2654-2663) and mounted onto a hybrid quadrupole time-of-flight mass spectrometer. Apple, cranberry, grape and orange juices as well as fruit peel

  3. Dynamic of the Dust Structures under Magnetic Field Effect in DC Glow Discharges

    SciTech Connect

    Vasiliev, M. M.; D'yachkov, L. G.; Antipov, S. N.; Petrov, O. F.; Fortov, V. E. [Joint Institute for High Temperatures, RAS, Izhorskaya 13/19, Moscow, Russia, 125412 (Russian Federation)

    2008-09-07

    In this work, we investigate dust structures in the striation of DC glow discharges under magnetic field actions. The dependence of rotation frequency of dusty plasma structures as a function of the magnetic field was investigated. For various magnetic fields kinetic temperatures of the dust particles, diffusion coefficients, and effective coupling coefficient {gamma}* have been determined. Obtained results are analyzed and compared with theoretical predictions.

  4. Properties of amorphous silicon tin alloys produced using the radio frequency glow discharge technique

    SciTech Connect

    Mahan, A.H.; Williamson, D.L.; Madan, A.

    1984-01-15

    Amorphous silicon tin films have been deposited by the glow discharge technique using SiH/sub 4/, H/sub 2/, and SnCl/sub 4/ or Sn (CH/sub 3/)/sub 4/ gas mixtures. An n to p-type conductivity transition with increasing Sn content in the films is found for both types of Sn alloying sources. Such a transition satisfactorily explains the observed dark and light conductivity behavior.

  5. Numerical Solutions to the Continuity Equation in the Negative-Glow-Faraday-Dark-Space Transition

    Microsoft Academic Search

    W. B. Hurt

    1971-01-01

    The one-dimensional charged-particle continuity equation with recombination-volume loss terms has been solved in a negative-glow-Faraday-dark-space environment without the usual assumptions neglecting the dependence of electron transport and recombination coefficients on the electric field. It is concluded that such assumptions are in serious error in the one-dimensional case and this raises the question of their effect on a three-dimensional model.

  6. Characterization of a glow discharge ion source for the mass spectrometric analysis of organic compounds

    Microsoft Academic Search

    D. Carazzato; M. J. Bertrand

    1994-01-01

    A glow discharge ion source has been constructed for the mass spectrometric analysis of organic compounds. Characterization\\u000a of the source has been made by studying the effect of pressure and discharge current on ionic distributions by anodic ion\\u000a sampling along the discharge axis. Ion and electron densities and electronic temperatures have been calculated by using the\\u000a single Langmuir probe technique

  7. Multidetector computed tomography of congenital aortic abnormalities.

    PubMed

    Lindsay, Alistair C; Sriharan, Mona; Lazoura, Olga; Padley, Simon P G; Nicol, Edward D; Rubens, Michael B

    2014-04-01

    For many years invasive angiographic techniques have been considered as the gold standard for the assessment of large arterial abnormalities. However, the complexities and complications inherent to invasive imaging have meant that more recently non-invasive techniques such as echocardiography, Magnetic Resonance Imaging (MRI) and multidetector CT (MDCT) have been increasingly used in congenital cardiovascular disorders. In particular, MDCT has emerged as a fundamental tool for the diagnosis and pre-surgical work-up of aortic abnormalities due to its high spatial resolution, large area of coverage, and short scan time, and therefore is now one of the most widely used modalities for the detection of congenital abnormalities of the aorta. The purpose of this pictorial review is to review the spectrum of abnormalities of the aorta than can be reliably detected by MDCT both in infants and in adulthood. Abnormalities of the aortic root, ascending aorta, aortic arch, and descending aorta will be described separately. PMID:24560026

  8. Transition from glow silent discharge to micro-discharges in nitrogen gas

    NASA Astrophysics Data System (ADS)

    Gherardi, Nicolas; Gouda, Gamal; Gat, Eric; Ricard, André; Massines, François

    2000-08-01

    At atmospheric pressure, the electrical breakdown of a silent discharge can occur in many thin filaments (leading to micro-discharges) or in a single discharge canal covering the entire electrode surface (leading to a glow discharge). The aim of this paper is to contribute to a better understanding of the transition from a glow silent discharge to micro-discharges in nitrogen at atmospheric pressure. For this purpose, the two types of regime have been studied by emission spectroscopy and electrical measurements. The transition is always observed due to an increase of the power dissipated in the gas gap, but the maximum power that can be used while maintaining a glow discharge depends on the nature of the dielectric surface in contact with the gas. These results have been explained by the predominance of the density of metastable nitrogen molecules on the discharge regime. Due to the creation of seed electrons via Penning ionization, these metastable molecules can control the gas breakdown and so the discharge regime. Their density essentially depends on their quenching rate. The products etched from the surfaces in contact with the discharge appear to be the main source of the metastable molecules quenching. Therefore, the nature of the surface controls the nature of the quenching of the metastable molecules and the power dissipated in the discharge the quencher density.

  9. Electron heating due to coulomb collisions between slow and intermediate electrons in DC glow discharges

    NASA Astrophysics Data System (ADS)

    Eliseev, Stepan; Kudryavtsev, Anatoliy

    2014-10-01

    As is known, the electrons in the cathode glow discharge plasma (negative glow and Faraday dark space) can be divided into three groups - slow, intermediate and fast electrons. Slow electrons, having maximum density, provide quasi-neutrality. They're locked in a potential well and have Maxwellian energy distribution. Fast electrons gain their energy in the cathode fall and maintain sufficient ionization in discharge. Intermediate electrons originate during ionization by fast electrons and carry current in the discharge. They have energies up to the threshold of inelastic collisions in the gas. At the same time they carry out their energy to the walls of the discharge and spend it on elastic collisions with gas atoms and Coulomb collisions with slow electrons and heat them. The amount of heating depends on the degree of ionization of gas, pressure, discharge tube size etc. The paper presents the results of a study on the impact of the heating on temperature and concentration of slow electrons in glow discharge.

  10. The role of electronic mechanisms in surface erosion and glow phenomena

    NASA Technical Reports Server (NTRS)

    Haglund, Richard F., Jr.

    1987-01-01

    Experimental studies of desorption induced by electronic transitions (DIET) are described. Such studies are producing an increasingly complete picture of the dynamical pathways through which incident electronic energy is absorbed and rechanneled to produce macroscopic erosion and glow. These mechanistic studies can determine rate constants for erosion and glow processes in model materials and provide valuable guidance in materials selection and development. Extensive experiments with electron, photon, and heavy particle irradiation of alkali halides and other simple model materials have produced evidence showing that: (1) surface erosion, consisting primarily in the ejection or desorption of ground-state neutral atoms, occurs with large efficiencies for all irradiated species; (2) surface glow, resulting from the radiative decay of desorbed atoms, likewise occurs for all irradiating species; (3) the typical mechanism for ground-state neutral desorption is exciton formation, followed by relaxation to a permanent, mobile electronic defect which is the precursor to bond-breaking in the surface or near-surface bulk of the material; and (4) the mechanisms for excited atom formation may include curve crossing in atomic collisions, interactions with surface defect or impurity states, or defect diffusion.

  11. Mixed-order kinetic analysis of the glow curve characteristics of single crystal LiF:Mg,Ti as a function of Ti concentration

    Microsoft Academic Search

    Y. Weizman; Y. S. Horowitz; L. Oster; D. Yossian; O. Bar-Lavy; A. Horowitz

    1998-01-01

    The glow curve characteristics of single crystal LiF:Mg,Ti, grown by the Bridgman method, were studied as a function of Ti concentration (3–14 ppm Ti). The glow curves were deconvoluted into component glow peaks using mixed-order (MO) model kinetics. The thermoluminescence (TL) sensitivities of all the low temperature peaks (peaks 2–5) increase with increasing Ti concentration, reaching a maximum at 12–13

  12. Influence of liquid temperature on the characteristics of an atmospheric dc glow discharge using a liquid electrode with a miniature helium flow

    Microsoft Academic Search

    Naoki Shirai; Kosuke Ichinose; Satoshi Uchida; Fumiyoshi Tochikubo

    2011-01-01

    An atmospheric dc glow discharge using a liquid cathode and an axial miniature helium flow was generated stably between a nozzle anode and an electrolyte cathode (NaCl solution) in ambient air. Under low-current operation, the typical structure of dc glow discharges, i.e. a negative glow, a Faraday dark space and positive column, was observed. With increasing discharge current, the visible

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

    NASA Astrophysics Data System (ADS)

    Reece Roth, J.

    2004-11-01

    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.

  14. Rare Cytogenetic Abnormalities in Myelodysplastic Syndromes

    PubMed Central

    Bacher, Ulrike; Schanz, Julie; Braulke, Friederike; Haase, Detlef

    2015-01-01

    The karyotype represents one of the main cornerstones for the International Prognostic Scoring System (IPSS) and the revised IPSS-R (IPSS-R) that are most widely used for prognostication in patients with myelodysplastic syndromes (MDS). The most frequent cytogenetic abnormalities in MDS, i.e. del(5q), -7/del(7q), +8, complex karyotypes, or ?Y have been extensively explored for their prognostic impact. The IPSS-R also considers some less frequent abnormalities such as del(11q), isochromosome 17, +19, or 3q abnormalities. However, more than 600 different cytogenetic categories had been identified in a previous MDS study. This review aims to focus interest on selected rare cytogenetic abnormalities in patients with MDS. Examples are numerical gains of the chromosomes 11 (indicating rapid progression), of chromosome 14 or 14q (prognostically intermediate to favorable), -X (in females, with an intermediate prognosis), or numerical abnormalities of chromosome 21. Structural abnormalities are also considered, e.g. del(13q) that is associated with bone marrow failure syndromes and favorable response to immunosuppressive therapy. These and other rare cytogenetic abnormalities should be integrated into existing prognostication systems such as the IPSS-R. However, due to the very low number of cases, this is clearly dependent on international collaboration. Hopefully, this article will help to inaugurate this process. PMID:25960862

  15. Numerically abnormal chromosome constitutions in humans

    SciTech Connect

    NONE

    1993-12-31

    Chapter 24, discusses numerically abnormal chromosome constitutions in humans. This involves abnormalities of human chromosome number, including polyploidy (when the number of sets of chromosomes increases) and aneuploidy (when the number of individual normal chromosomes changes). Chapter sections discuss the following chromosomal abnormalities: human triploids, imprinting and uniparental disomy, human tetraploids, hydatidiform moles, anomalies caused by chromosomal imbalance, 13 trisomy (D{sub 1} trisomy, Patau syndrome), 21 trisomy (Down syndrome), 18 trisomy syndrome (Edwards syndrome), other autosomal aneuploidy syndromes, and spontaneous abortions. The chapter concludes with remarks on the nonrandom participation of chromosomes in trisomy. 69 refs., 3 figs., 4 tabs.

  16. Abnormalities of lung function in hay fever.

    PubMed Central

    Morgan, E J; Hall, D R

    1976-01-01

    Twenty subjects with symptoms of hay fever were studied to see whether abnormalities could be detected in the function of small airways. The investigations included dynamic compliance at varying respiratory frequencies, closing capacity, residual volume, transfer factor, and maximal expiratory flow-volume curves. The tests were repeated in the winter when symptoms had resolved. Frequency dependence of compliance was found in eight subjects with symptoms (40%), closing capacities being abnormal in only two instances. Conventional pulmonary function tests, including expiratory flow rates at mid vital capacity, were within the predicted range of all subjects. When tests were repeated in the winter, frequency dependence of compliance was no longer present in subjects whose symptoms had resolved. The study suggests that reversible small airway abnormalities are present in a significant proportion of subjects with symptoms of hay fever and that such abnormalities are best detected by the measurement of dynamic compliance at varying respiratory frequencies. PMID:769243

  17. Four families with immunodeficiency and chromosome abnormalities.

    PubMed Central

    Candy, D C; Hayward, A R; Hughes, D T; Layward, L; Soothill, J F

    1979-01-01

    Six children, with severe deficiency of some or all of the immunoglobulins and minor somatic abnormalities, had chromosomal abnormalities: (1) 45,XY,t(13q/18q), (2) 46,XY,21ps +, (3) two brothers 46,XY (inv. 7) (4) 45,X,t(11p/10p)/46X,iXq,t(11p/10p) and, (5) in addendum, 45,XX,-18;46,XX, r18. The chromosome abnormalities were detected in B- as well as T-lymphocytes (as evidenced by using both PHA- and PWM-stimulated cultures) in all probands, but one was mosaic in PHA culture, although all his PWM-stimulated cells were abnormal. Chromosomal variants were also detected in relatives of three and immunodeficiency in relatives of two. Images Fig. 1 Fig. 3 PMID:314782

  18. Abnormal Cervical Cancer Screening Test Results

    MedlinePLUS

    ... freeze abnormal cervical tissue, which then sloughs off. • Laser therapy—A focused beam of light is used ... tissue is removed from the cervix. Cryotherapy: A freezing technique used to destroy diseased tissue; also known ...

  19. Pinna abnormalities and low-set ears

    MedlinePLUS

    ... Common abnormalities include cysts in the pinna or skin tags . Many children are born with ears that stick ... affect hearing. However, sometimes cosmetic surgery is recommended. Skin tags may be tied off, unless there is cartilage ...

  20. T cell immune abnormalities in immune thrombocytopenia.

    PubMed

    Ji, Xuebin; Zhang, Liping; Peng, Jun; Hou, Ming

    2014-01-01

    Immune thrombocytopenia is an autoimmune disease with abnormal T cell immunity. Cytotoxic T cells, abnormal T regulatory cells, helper T cell imbalance, megakaryocyte maturation abnormalities and abnormal T cell anergy are involved in the pathogenesis of this condition. The loss of T cell-mediated immune tolerance to platelet auto-antigens plays a crucial role in immune thrombocytopenia. The induction of T cell tolerance is an important mechanism by which the pathogenesis and treatment of immune thrombocytopenia can be studied. Studies regarding the roles of the new inducible costimulator signal transduction pathway, the ubiquitin proteasome pathway, and the nuclear factor kappa B signal transduction pathway in the induction of T cell tolerance can help improve our understanding of immune theory and may provide a new theoretical basis for studying the pathogenesis and treatment of immune thrombocytopenia. PMID:25274611

  1. ICSN Data - Abnormal Result Technologies and Procedures

    Cancer.gov

    Skip to Main Content Search International Cancer Screening Network Sponsored by the National Cancer Institute Home | About ICSN | Collaborative Projects | Meetings | Cancer Sites | Publications | Contact Us Breast Cancer (Archived Tables): Home Abnormal

  2. Optical and electrical characteristics of air dielectric barrier discharges in mode transition at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Wang, Weiwei; Liu, Feng; Wang, Xue; Han, Haiyan; Huang, Yanbin; Liang, Rongqing

    2015-04-01

    Atmospheric pressure dielectric barrier discharges (DBDs) have a wide range of industrial applications, generally exhibiting either filamentary or diffuse (i.e. glow) discharges. The focus of this investigation is on the formation mechanisms of the discharge current pulse width, on the order of tens of microseconds, accompanied by a light source formation, which is called a light source (LS) mode in air DBDs at atmospheric pressure. From a macroscopic point of view, the characteristics of the discharge current in the LS mode are similar with those of the glow mode. The optical and electrical characteristics of air DBDs at atmospheric pressure are investigated in the transition from the filamentary mode to the LS mode by measuring the optical emission spectroscopy and electrical signals. It is shown that in the manual increasing voltage stage, the vibrational temperature almost never changes and the gas temperature, electron temperature, dielectric capacitance, gas voltage (Vg) and discharge power (P) increase with an increase in the applied voltage. In the automatic decreasing voltage stage, all of these parameters, except Vg and P, increase with a decrease in the voltage. But, when the voltage decreases to a minimum value corresponding to the LS mode, P reaches a maximum value. In this paper, the variations of these parameters are analyzed and discussed in detail. The formation of the LS mode originates from the secondary electrons. The formation mechanisms of the secondary electrons are also discussed.

  3. Normal and Abnormal Behavior in Early Childhood

    PubMed Central

    Spinner, Miriam R.

    1981-01-01

    Evaluation of normal and abnormal behavior in the period to three years of age involves many variables. Parental attitudes, determined by many factors such as previous childrearing experience, the bonding process, parental psychological status and parental temperament, often influence the labeling of behavior as normal or abnormal. This article describes the forms of crying, sleep and wakefulness, and affective responses from infancy to three years of age. PMID:21289833

  4. 21 CFR 864.7415 - Abnormal hemoglobin assay.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 false Abnormal hemoglobin assay. 864.7415 Section 864.7415 Food...Packages § 864.7415 Abnormal hemoglobin assay. (a) Identification. An abnormal hemoglobin assay is a device consisting of the...

  5. The chemically synthesized ageladine A-derivative LysoGlow84 stains lysosomes in viable mammalian brain cells and specific structures in the marine flatworm Macrostomum lignano.

    PubMed

    Mordhorst, Thorsten; Awal, Sushil; Jordan, Sebastian; Petters, Charlotte; Sartoris, Linda; Dringen, Ralf; Bickmeyer, Ulf

    2015-02-01

    Based on the chemical structure and the known chemical synthesis of the marine sponge alkaloid ageladine A, we synthesized the ageladine A-derivative 4-(naphthalene-2-yl)-1H-imidazo[4,5-c]pyridine trifluoroacetate (LysoGlow84). The two-step synthesis started with the Pictet-Spengler reaction of histamine and naphthalene-2-carbaldehyde to a tetrahydropyridine intermediate, which was dehydrogenated with activated manganese (IV) oxide to LysoGlow84. Structure and purity of the synthesized LysoGlow84 were confirmed by NMR spectroscopy and mass spectrometry. The fluorescence intensity emitted by LysoGlow84 depended strongly on the pH of the solvent with highest fluorescence intensity recorded at pH 4. The fluorescence maximum (at 315 nm excitation) was observed at 440 nm. Biocompatibility of LysoGlow84 was investigated using cultured rat brain astrocytes and the marine flatworm Macrostomum lignano. Exposure of the astrocytes for up to 6 h to micromolar concentrations of LysoGlow84 did not compromise cell viability, as demonstrated by several viability assays, but revealed a promising property of this compound for staining of cellular vesicles. Conventional fluorescence microscopy as well as confocal scanning microscopy of LysoGlow84-treated astrocytes revealed co-localization of LysoGlow84 fluorescence with that of LysoTracker® Red DND-99. LysoGlow84 stained unclear structures in Macrostomum lignano, which were identified as lysosomes by co-staining with LysoTracker. Strong fluorescence staining by LysoGlow84 was further observed around the worms' anterior gut and the female genital pore which were not counterstained by LysoTracker Red. Thus, LysoGlow84 is a new promising dye that stains lysosomes and other acidic compartments in cultured cells and in worms. PMID:25679913

  6. 21 CFR 864.7415 - Abnormal hemoglobin assay.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...a) Identification. An abnormal hemoglobin assay is a device consisting of the reagents, apparatus, instrumentation, and controls necessary to isolate and identify abnormal genetically determined hemoglobin types. (b)...

  7. 21 CFR 864.7415 - Abnormal hemoglobin assay.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...a) Identification. An abnormal hemoglobin assay is a device consisting of the reagents, apparatus, instrumentation, and controls necessary to isolate and identify abnormal genetically determined hemoglobin types. (b)...

  8. Fetal Calcifications Are Associated with Chromosomal Abnormalities

    PubMed Central

    Sahlin, Ellika; Sirotkina, Meeli; Marnerides, Andreas

    2015-01-01

    Objective The biological importance of calcifications occasionally noted in fetal tissues (mainly liver) at autopsy or ultrasound is largely unexplored. Previous reports hint at an association to infection, circulatory compromise, malformations or chromosomal abnormalities. To identify factors associated with calcifications, we have performed a case-control study on the largest cohort of fetuses with calcifications described thus far. Methods One-hundred and fifty-one fetuses with calcifications and 302 matched controls were selected from the archives of the Department of Pathology, Karolinska University Hospital. Chromosome analysis by karyotyping or quantitative fluorescence-polymerase chain reaction was performed. Autopsy and placenta reports were scrutinized for presence of malformations and signs of infection. Results Calcifications were mainly located in the liver, but also in heart, bowel, and other tissues. Fetuses with calcifications showed a significantly higher proportion of chromosomal abnormalities than controls; 50% vs. 20% (p<0.001). The most frequent aberrations among cases included trisomy 21 (33%), trisomy 18 (22%), and monosomy X (18%). A similar distribution was seen among controls. When comparing cases and controls with chromosomal abnormalities, the cases had a significantly higher prevalence of malformations (95% vs. 77%, p=0.004). Analyzed the other way around, cases with malformations had a significantly higher proportion of chromosomal abnormalities compared with controls, (66% vs. 31%, p<0.001). Conclusion The presence of fetal calcifications is associated with high risk of chromosomal abnormality in combination with malformations. Identification of a calcification together with a malformation at autopsy more than doubles the probability of detecting a chromosomal abnormality, compared with identification of a malformation only. We propose that identification of a fetal tissue calcification at autopsy, and potentially also at ultrasound examination, should infer special attention towards co-existence of malformations, as this would be a strong indicator for a chromosomal abnormality. PMID:25923652

  9. Amplification, current-voltage variations, and refraction in the interaction between millimeter-wave radiation and the glow-discharge plasma

    Microsoft Academic Search

    A. Rosenberg; Y. Ben-Aryeh; J. Politch; J. Felsteiner

    1982-01-01

    The amplification of millimeter electromagnetic radiation within the cathode region of a cold-cathode glow discharge is correlated with the variations in the current-voltage characteristic of the glow discharge. The transfer of energy from the fast electrons to the electromagnetic wave amplifies the incident radiation and also causes a decrease in discharge current. The latter is called the \\

  10. PHYSICAL REVIEW E 84, 026403 (2011) Observations of a structure-forming instability in a dc-glow-discharge dusty plasma

    E-print Network

    Merlino, Robert L.

    2011-01-01

    discharge dusty plasmas [2]. However, the ionization instability can also lead to the forma-glow-discharge dusty plasma J. R. Heinrich, S.-H. Kim, and R. L. Merlino Department of Physics and Astronomy-glow-discharge dusty plasma, we have found plasma and dust conditions conducive to dusty plasma structurization

  11. On the feasibility of inversion methods based on models of urban sky glow

    NASA Astrophysics Data System (ADS)

    Kolláth, Z.; Kránicz, B.

    2014-05-01

    Multi-wavelength imaging luminance photometry of sky glow provides a huge amount of information on light pollution. However, the understanding of the measured data involves the combination of different processes and data of radiation transfer, atmospheric physics and atmospheric constitution. State-of-the-art numerical radiation transfer models provide the possibility to define an inverse problem to obtain information on the emission intensity distribution of a city and perhaps the physical properties of the atmosphere. We provide numerical tests on the solvability and feasibility of such procedures.

  12. Ion implantation and energy loss effect during high-voltage pulsed glow discharge in a tube

    SciTech Connect

    Wang Langping; Lu Yang; Wang Xiaofeng; Xie Zhiwen; Huang Lei; Wei Yanhong [State Key Laboratory of Advanced Welding Production and Technology, Harbin Institute of Technology, Harbin 150001 (China)

    2009-09-07

    Plasma parameters of high-voltage pulsed glow discharge in a tube were studied using a static probe and optical emission spectrometry. Experiment results show that two kinds of plasma can be obtained in the tube and a virtual anode can be formed at the center of the tube. The potential of the virtual anode is about 20%-30% of the applied bias. The Auger electron spectroscopy depth profile shows that the peak depth of the implanted ions in the tube is about 70%-80% of that outside the tube, owing to the virtual anode.

  13. Measurements of helium metastable density in an atmospheric pressure glow discharge

    SciTech Connect

    Nersisyan, G.; Morrow, T.; Graham, W.G. [Physics Department, Queen's University Belfast, Belfast BT7 1NN, Northern Ireland (United Kingdom)

    2004-08-30

    The density of metastable helium atoms in a dielectric barrier discharge operating in helium with some impurities present has been measured using laser-collisional-induced fluorescence and absorption techniques. Time-resolved measurements indicate that helium metastables contribute to the production of impurity ions, in this case N{sub 2}{sup +}, in the postdischarge current phase of a glow discharge. In our particular discharge environment, the helium metastable density is (1.5{+-}1.4)x10{sup 10} cm{sup -3}, a result consistent with failure to observe absorption by metastables in a multipass absorption measurement.

  14. Method to measure the electric field vector in an argon glow discharge using laser polarization spectroscopy.

    PubMed

    Gavrilenko, V P; Kim, H J; Ikutake, T; Kim, J B; Bowden, M D; Muraoka, K

    2001-04-01

    A method for measurement of the direction of the electric field in a glow discharge is reported. This method uses the dependence of the electronic excitation spectrum of argon atoms on the polarization of the laser radiation. In this research, laser radiation was used to excite argon atoms in a plasma from the 4s [3 / 2](2) metastable level to Rydberg levels, and excitation spectra were measured using laser optogalvanic (LOG) spectroscopy. In addition, LOG spectra of argon atoms interacting with an electric field were calculated by solving the Schrödinger equation. Good agreement was found between experimental and theoretical LOG spectra obtained for different polarizations of the laser radiation. PMID:11308986

  15. Dependence of the dust-particle charge on its size in a glow-discharge plasma.

    PubMed

    Fortov, V E; Nefedov, A P; Molotkov, V I; Poustylnik, M Y; Torchinsky, V M

    2001-11-12

    Measurements of the charge of dust grains have been performed in a quasineutral plasma over a wide range of grain sizes. A new method was established for measuring the charge on grains levitating in the striations of a dc glow discharge. A single dust particle is moved out of a dust cloud with the help of a focused laser beam. When it leaves the beam it returns back to the cloud, and the charge on the grain is derived from the analysis of the returning trajectory. The obtained dependence of the dust-grain charge on its size was found to be strongly nonlinear in the experimental conditions. PMID:11690478

  16. Numerical study of the normal current density behaviour in a narrow - gap glow discharge

    E-print Network

    Starostin, S A; Kindel, E; Azarov, A V; Mitko, S V; Boller, K

    2004-01-01

    A numerical study of normal glow discharge properties was performed in the case of small electrodes separations (0.05-0.4 cm) and moderate gas pressures (10-46 Torr). A recently observed new experimental effect of a considerable reduction in the normal current density for smaller discharge lengths was analyzed both by means of 2D fluid model and by a minimal 1D drift model of gas discharge. A good agreement between theoretical and experimental behaviour was demonstrated. An influence of the electrodes separation and of the gas heating on the value of the normal current density is discussed.

  17. Formation and dynamics of nano-particles in a stratified spherical glow discharge

    NASA Astrophysics Data System (ADS)

    Sakhapov, S. Z.; Fedoseev, A. V.; Sukhinin, G. I.; Novopashin, S. A.

    2015-04-01

    The formation of clouds of dust nano-particles in a spherical dc glow discharge in ethanol was observed. Nano-particles were formed in a process of coagulation of ethanol dissociation products in a plasma of gas discharge. During the process the particles were captured into clouds in the electric potential wells of the strong striations of a spherical discharge. Periodically, the cloud of nano-particles experienced some sudden instability (explosion), and started to move to the cathode at high velocity. It was proved that the velocity of the particle clouds was an exponentially decaying function of time as in the case of dissipative dust solitary waves.

  18. Generation of O2 From CO2 by Glow Discharge And Permeation

    NASA Technical Reports Server (NTRS)

    Outlaw, R. A.

    1993-01-01

    Technique for generating supply of highly pure O2 from CO2 developed. First, atomic oxygen at useful partial pressure generated by glow-discharge dissociation of CO2. Atomic oxygen formed in vicinity of hot silver membrane and permeates through membrane to downstream region, where thermally recombined into O2 and pumped away to storage tank. Pure oxygen stored suitable for human consumption and other uses. Originally developed to convert Martian atmosphere of CO2 to O2 for astronaut consumption. Other potential applications include purification of atmospheres in Space Shuttle and Space Station Freedom. Byproduct CO must be handled by other techniques.

  19. Seasonal trends and nightly fluctuations of SWIR air-glow irradiance

    NASA Astrophysics Data System (ADS)

    Dayton, David C.; Allen, Jeffrey; Nolasco, Rudolph; Gonglewski, John D.; Myers, Michael; Fertig, Gregory

    2011-11-01

    It is well known that luminance from photo-chemical reactions of hydroxyl ions in the upper atmosphere (~85 km altitude) produces a significant amount of night time radiation in the short wave infra-red (SWIR) band with wavelength between 0.9 and 1.7 ?m. This air glow has been proposed as an illumination source for obtaining imagery in the dark of night. By examining short term nightly fluctuations and long term seasonal trends in the ground level irradiance we hope to determine the source reliability for night time low light surveillance and imaging.

  20. Modeling of a short (without positive column) glow discharge with active boundaries

    NASA Astrophysics Data System (ADS)

    Kudryavtsev, Anatoly; Barzilovich, Konstantin; Bogdanov, Eugene; Kolobov, Vladimir

    2013-10-01

    As boundaries are very important in formation of nonlocal plasma properties, in this study a short dc discharge with cold cathode and application of different voltages to the conducting discharge wall has been simulated. The discharge model is based on a fluid description of ions and neutral species using drift-diffusion approximation for the particle flux. The description of electrons is based on a ``hybrid'' approach with subdivision for trapped and free (fast) electrons. Slow electron transport coefficients as well as electron induced reaction rates are determined from the solutions of the electron Boltzmann equation. The self-consistent electric field is calculated using the Poisson equation. 2D simulations for helium plasma at 1 Torr pressure confirm that the short glow discharge consists of cathode and anode sheaths of space charges, a cathode plasma negative glow, and a Faraday dark space. The plasma region characterized by low electron temperature and weak reversed electric field. It is demonstrated in the model that applied voltage can trap within the device volume energetic electrons arising from atomic and molecular processes in the plasma. It allows measurement of the fast part of the EDF by application of measuring wall electrode. As boundaries are very important in formation of nonlocal plasma properties, in this study a short dc discharge with cold cathode and application of different voltages to the conducting discharge wall has been simulated. The discharge model is based on a fluid description of ions and neutral species using drift-diffusion approximation for the particle flux. The description of electrons is based on a ``hybrid'' approach with subdivision for trapped and free (fast) electrons. Slow electron transport coefficients as well as electron induced reaction rates are determined from the solutions of the electron Boltzmann equation. The self-consistent electric field is calculated using the Poisson equation. 2D simulations for helium plasma at 1 Torr pressure confirm that the short glow discharge consists of cathode and anode sheaths of space charges, a cathode plasma negative glow, and a Faraday dark space. The plasma region characterized by low electron temperature and weak reversed electric field. It is demonstrated in the model that applied voltage can trap within the device volume energetic electrons arising from atomic and molecular processes in the plasma. It allows measurement of the fast part of the EDF by application of measuring wall electrode. This work has been supported by SPbSU and FZP.

  1. Effect of fluorine on the photovoltaic properties of amorphous silicon prepared by dc glow discharge

    NASA Astrophysics Data System (ADS)

    Nishihata, K.; Konagai, M.; Takahashi, K.; Komori, K.

    Amorphous Si-F-H films were prepared by dc glow discharge in an atmosphere of SiF4 + H2. The electrical and optical properties have been described. Infrared spectra of amorphous Si-F-H have been studied for various deposition pressures. In the n-type doping characteristics, the maximum conductivity obtained is 10.0/ohm-cm with the addition of 500 vppm PH3. The Schottky barrier a-Si-F-H solar cell shows an efficiency of 3.5% under AM1, 100 mW/sq cm insolation.

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

    SciTech Connect

    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

    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.

  3. Nonlocal control of electron temperature in short direct current glow discharge plasma

    SciTech Connect

    Demidov, V. I. [Department of Optics and Spectroscopy, St. Petersburg State University, St. Petersburg 199034 (Russian Federation); International Laboratory “Nonlocal Plasma in Nanotechnology and Medicine”, ITMO University, Kronverkskiy pr. 49, St. Petersburg 197101 (Russian Federation); Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506 (United States); Kudryavtsev, A. A.; Stepanova, O. M. [Department of Optics and Spectroscopy, St. Petersburg State University, St. Petersburg 199034 (Russian Federation); Kurlyandskaya, I. P. [International Laboratory “Nonlocal Plasma in Nanotechnology and Medicine”, ITMO University, Kronverkskiy pr. 49, St. Petersburg 197101 (Russian Federation); St. Petersburg University of State Fire Service of EMERCOM RF, Murmansk Branch, Murmansk 183040 (Russian Federation)

    2014-09-15

    To demonstrate controlling the electron temperature in nonlocal plasma, experiments have been performed on a short (without positive column) dc glow discharge with a cold cathode by applying different voltages to the conducting discharge wall. The experiments have been performed for low-pressure noble gas discharges. The applied voltage can modify trapping the energetic electrons emitted from the cathode sheath and arising from the atomic and molecular processes in the plasma within the device volume. This phenomenon results in the energetic electrons heating the slow plasma electrons, which consequently modifies the electron temperature. Furthermore, a numerical model of the discharge has demonstrated the electron temperature modification for the above case.

  4. Abnormal hepatocellular mitochondria in methylmalonic acidemia.

    PubMed

    Wilnai, Yael; Enns, Gregory M; Niemi, Anna-Kaisa; Higgins, John; Vogel, Hannes

    2014-10-01

    Methylmalonic acidemia (MMA) is one of the most frequently encountered forms of branched-chain organic acidemias. Biochemical abnormalities seen in some MMA patients, such as lactic acidemia and increased tricarboxylic acid cycle intermediate excretion, suggest mitochondrial dysfunction. In order to investigate the possibility of mitochondrial involvement in MMA, we examined liver tissue for evidence of mitochondrial ultrastructural abnormalities. Five explanted livers obtained from MMA mut(0) patients undergoing liver transplantation were biopsied. All patients had previous episodes of metabolic acidosis, lactic acidemia, ketonuria, and hyperammonemia. All biopsies revealed a striking mitochondriopathy by electron microscopy. Mitochondria were markedly variable in size, shape, and conformation of cristae. The inner matrix appeared to be greatly expanded and the cristae were diminutive and disconnected. No crystalloid inclusions were noted. This series clearly documents extensive mitochondrial ultrastructure abnormalities in liver samples from MMA patients undergoing transplantation, providing pathological evidence for mitochondrial dysfunction in the pathophysiology of MMA mut(0). Considering the trend to abnormally large mitochondria, the metabolic effects of MMA may restrict mitochondrial fission or promote fusion. The correlation between mitochondrial dysfunction and morphological abnormalities in MMA may provide insights for better understanding and monitoring of optimized or novel therapeutic strategies. PMID:24933007

  5. Electroencephalographic abnormalities in patients with snake bites.

    PubMed

    Ramachandran, S; Ganaikabahu, B; Pushparajan, K; Wijesekera, J

    1995-01-01

    Electroencephalograms (EEGs) were obtained for 26 patients with snake bite to observe the cerebral impact of snake venom. All snakes were identified; 19 (73%) were Russell's vipers, one (4%) was a common cobra, five (19%) were hump-nosed vipers, and one (4%) was a dog-faced fresh water snake. The EEG was abnormal in 25 patients (96%) and these results included all the snake species identified. The EEG abnormalities observed were reduced alpha activity, increased theta/beta activity or sharp waves (grade 1), sharp waves or spikes and slow waves (grade 2), or diffuse delta activity (grade 3). Grade 1 changes occurred in 16 patients (62%), grade 11 in eight patients (31%), and grade 111 in one patient (4%). Thus, grade 2 and 3 changes, which were moderately severe to severe abnormalities, occurred in nine patients (35%). One patient had acute renal failure and two others had mild jaundice and hyponatremia. These three patients had EEG abnormalities that were similar to those observed in the remaining 22 patients. The altered EEG, suggestive of an encephalopathy, appeared within hours of the bite and persisted for several days without clinical neurologic effects. The changes were seen mainly in the temporal lobe. Similar changes occurred in both patients with and without antivenom therapy. It appeared that the EEG abnormalities are a consequence of the effects of venom from the bites of a variety of snakes. PMID:7856822

  6. Hydrogenated amorphous silicon and silicon germanium triple-junction solar cells at high rate using RF and VHF glow discharges

    Microsoft Academic Search

    Guozhen Yue; Baojie Yan; Jeffrey Yang; Subhendu Guha

    2008-01-01

    We present our recent results on a-Si:H\\/a-SiGe:H\\/a-SiGe:H triple-junction solar cells made at high deposition rates using both RF and MVHF glow discharges. The growth parameters studied are under the constraints of manufacturing feasibility so that any improvement can be transferred to manufacturing lines. Using RF glow discharge, we achieved initial active-area efficiencies of 11.4% and 12.5% on Al\\/ZnO and Ag\\/ZnO

  7. Advances in understanding paternally transmitted Chromosomal Abnormalities

    SciTech Connect

    Marchetti, F; Sloter, E; Wyrobek, A J

    2001-03-01

    Multicolor FISH has been adapted for detecting the major types of chromosomal abnormalities in human sperm including aneuploidies for clinically-relevant chromosomes, chromosomal aberrations including breaks and rearrangements, and other numerical abnormalities. The various sperm FISH assays have been used to evaluate healthy men, men of advanced age, and men who have received mutagenic cancer therapy. The mouse has also been used as a model to investigate the mechanism of paternally transmitted genetic damage. Sperm FISH for the mouse has been used to detect chromosomally abnormal mouse sperm, while the PAINT/DAPI analysis of mouse zygotes has been used to evaluate the types of chromosomal defects that can be paternally transmitted to the embryo and their effects on embryonic development.

  8. Referenceless stratification of parenchymal lung abnormalities.

    PubMed

    Raghunath, Sushravya; Rajagopalan, Srinivasan; Karwoski, Ronald A; Bartholmai, Brian J; Robb, Richard A

    2011-01-01

    This paper introduces computational tools that could enable personalized, predictive, preemptive, and participatory (P4) Pulmonary medicine. We demonstrate approaches to (a) stratify lungs from different subjects based on the spatial distribution of parenchymal abnormality and (b) visualize the stratification through glyphs that convey both the grouping efficacy and an iconic overview of an individual's lung wellness. Affinity propagation based on regional parenchymal abnormalities is used in the referenceless stratification. Abnormalities are computed using supervised classification based on Earth Mover's distance. Twenty natural clusters were detected from 372 CT lung scans. The computed clusters correlated with clinical consensus of 9 disease types. The quality of inter- and intra-cluster stratification as assessed by ANOSIM R was 0.887 +/- 0.18 (pval < 0.0005). The proposed tools could serve as biomarkers to objectively diagnose pathology, track progression and assess pharmacologic response within and across patients. PMID:22003703

  9. Characterization of a glow discharge ion source for the mass spectrometric analysis of organic compounds.

    PubMed

    Carazzato, D; Bertrand, M J

    1994-04-01

    A glow discharge ion source has been constructed for the mass spectrometric analysis of organic compounds. Characterization of the source has been made by studying the effect of pressure and discharge current on ionic distributions by anodic ion sampling along the discharge axis. Ion and electron densities and electronic temperatures have been calculated by using the single Langmuir probe technique to correlate the extraction efficiency with measured ion distributions and gain some insight into the ionization of organic molecules. The spectra obtained for several classes of organic compounds show that formation of parent-molecular ions by proton transfer, resulting partly from the background water molecules, is a major low energy process while charge transfer, Penning ionization, and electron ionization ace probably responsible for the fragmentation observed. The spectra result from the simultaneous occurrence of high and low energy reactions, and their structural information content is very high, yielding both molecular and extensive fragment ion information. The glow discharge ion source has proved to be essentially maintenance-free, easy to operate, stable, and can be used at reasonable mass resolution (up to 70001. The source also provides picogram range detection limits and has a linear response range of about six orders of magnitude, which makes it an interesting ion source for routine analysis. Preliminary work conducted with chromatographic interfaces indicates that its use can be easily extended to both gas and liquid chromatography. PMID:24222568

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

    SciTech Connect

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

    2007-12-15

    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.

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

    SciTech Connect

    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

    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.

  12. Decomposition of toluene in a steady-state atmospheric-pressure glow discharge

    NASA Astrophysics Data System (ADS)

    Trushkin, A. N.; Grushin, M. E.; Kochetov, I. V.; Trushkin, N. I.; Akishev, Yu. S.

    2013-02-01

    Results are presented from experimental studies of decomposition of toluene (C6H5CH3) in a polluted air flow by means of a steady-state atmospheric pressure glow discharge at different water vapor contents in the working gas. The experimental results on the degree of C6H5CH3 removal are compared with the results of computer simulations conducted in the framework of the developed kinetic model of plasma chemical decomposition of toluene in the N2: O2: H2O gas mixture. A substantial influence of the gas flow humidity on toluene decomposition in the atmospheric pressure glow discharge is demonstrated. The main mechanisms of the influence of humidity on C6H5CH3 decomposition are determined. The existence of two stages in the process of toluene removal, which differ in their duration and the intensity of plasma chemical decomposition of C6H5CH3 is established. Based on the results of computer simulations, the composition of the products of plasma chemical reactions at the output of the reactor is analyzed as a function of the specific energy deposition and gas flow humidity. The existence of a catalytic cycle in which hydroxyl radical OH acts a catalyst and which substantially accelerates the recombination of oxygen atoms and suppression of ozone generation when the plasma-forming gas contains water vapor is established.

  13. Effect of volume and surface charges on discharge structure of glow dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Xu, Shao-Wei; He, Feng; Wang, Yu; Li, Lulu; Ouyang, Ji-Ting

    2013-08-01

    The effect of volume and surface charges on the structure of glow dielectric barrier discharge (DBD) has been investigated numerically by using two-dimensional (2D) fluid modeling. The local increase of volume or surface charges induces a kind of activation-inhibition effect, which enhances the local volume discharge and inhibits the discharge in neighborhoods, resulting in non-uniform discharge. The activation-inhibition effect due to the non-uniform volume and/or surface charges depends on the non-uniformity itself and the applied voltage. The activation-inhibition of non-uniform charges has different effects on the volume charges and the accumulated surface charges. The distribution of remaining free charges (seed electrons) in volume at the beginning of voltage pulse plays a key role for the glow DBD structure, resulting in a patterned DBD, when the seed electrons are non-uniform at higher frequency and moderate voltage or uniform DBD, when the seed electrons are uniform at lower frequency or high voltage. The distribution of surface charges is not the determining factor but a result of the formed DBD structure.

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

    NASA Astrophysics Data System (ADS)

    Nozaki, Tomohiro; Okazaki, Ken; Kortshagen, Uwe; Heberlein, Joachim

    2003-10-01

    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 ( ˜10vol%) in order to etch out excess carbon deposited on Ni particle. Highly contaminated helium tends to form filamentary discharges, and then severely deteriorates deposited materials. It also limits operating conditions such as gap separation, voltage amplitude, and so on. The stability issue will be extensively discussed in terms of emission spectroscopy which also makes clear chemical processes. Nanotubes vertically grow in the presence of directional electric field, and this is a big challenge in barrier discharges because dielectric barrier forces to use AC voltage to maintain stable plasma conditions. Alignment of nanotube also depends on carbon sources. C2H2 generally provides curly nanotubes, whereas rather straight nanotubes likely grow with methane. Control growth of nanotube will be discussed based on voltage waveform (Sin/Pulse) and carbon source.

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

    SciTech Connect

    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

    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.

  16. [Diagnosis of the DC glow discharge plasma generated inside a metallic tube by optical emission spectroscopy].

    PubMed

    Yin, Li-yong; Wen, Xiao-qiong; Wang, De-zhen

    2008-12-01

    Optical emission spectroscopy method was used to diagnose the normal dc glow discharge plasma generated inside a metallic tube. The active species in the plasma were identified. The electron excitation temperature in the plasma was determined by the Boltzmann plot method. The vibrational temperature of N2 molecules in the plasma was determined by analyzing the emission spectrum lines of the N2 second positive system (C3 IIu-->B 3IIg). The dependence of the electron excitation temperature and molecular vibrational temperature on the pressure was investigated. The experiment results show that in the Ar 60% + N2 40% glow discharge plasma at 20 Pa, the active species are the Ar atoms, Ar ions, second positive series of N transitions and theE first negative series of B (2)II2u-->X 2sigma g+; transitons; the electron excitation temperature is (15 270 +/- 250) K, and the vibrational temperature of N2 molecules is (3 290 +/- 100) K. The electron excitation temperature and molecular vibrational temperature decrease with increasing pressure. These results would give some valuable guide to the study on inner surface modification of metallic tubes. PMID:19248474

  17. Physical model of anode glow patterns in elevated-pressure gas discharges.

    PubMed

    Islamov, R S

    2001-10-01

    A physical self-consistent model is developed to explain single spots or complex current structures at the anode of elevated-pressure parallel-plate dc discharges. The model is based on a fluid description of electron and ion transport coupled with Poisson's equation and involves a pair of coupled reaction-diffusion equations of an activator-inhibitor-type. This system of one-dimensional equations containing no phenomenological (adjustable) parameters allows one to find the current-density (activator) and anode potential drop (inhibitor) distributions on the anode surface. In a certain range of supply voltage, an anode glow stratification, resulting in the formation of separate glowing regions, takes place. However, the growth of perturbations and formation of a spatially periodic current pattern are complicated by competition between the current stripes, leading to suppressing of the neighboring current stripes. The bifurcation behavior of the model with respect to the characteristic electron energy, recombination coefficient, and discharge gap has been analyzed. The properties of a single anode current structure, including the normal current density effect, have been investigated. The application of these results to available findings in experiments and two-dimensional numerical simulations is discussed. PMID:11690154

  18. Measurement of gas temperature and convection velocity profiles in a dc atmospheric glow discharge

    SciTech Connect

    Stepaniuk, Vadim P.; Ioppolo, Tindaro; Oetuegen, M. Volkan; Sheverev, Valery A. [Lenterra Inc., 7 Tenney Road, West Orange, New Jersey 07052 (United States); Polytechnic University, 6 Metrotech Center, Brooklyn, New York 11201 (United States); Mechanical Engineering Department, Southern Methodist University, P. O. Box 750337, Dallas, Texas 75275 (United States); Polytechnic University, 6 Metrotech Center, Brooklyn, New York 11201 (United States)

    2007-12-15

    Gas temperature and convective velocity distributions are presented for an unconfined glow discharge in air at atmospheric pressure, with electric currents ranging between 30 and 92 mA. The vertically oriented discharge was formed between a pin anode (top) and an extended cathode. The temperature and velocity profiles were measured using laser-induced Rayleigh scattering and laser Doppler anemometry techniques, respectively. The temperature field exhibited a conical shape with the radius of hot temperature zone increasing toward the anode. A maximum temperature of 2470 K was observed on the discharge axis with the discharge current of 92 mA. Air velocity measurements around the discharge demonstrated that the shape and magnitude of the temperature field are strongly affected by natural convection. Estimates indicate that convective losses may account for more than 50% of the power input into the positive column of the discharge. The measured temperature fields and convective velocity profiles provide a set of data that is important for the evaluation of dc atmospheric glow discharges in various applications such as sound manipulation and acoustic noise mitigation.

  19. Atmospheric dc glow discharge using liquid anode for production of nano-particle

    NASA Astrophysics Data System (ADS)

    Shirai, Naoki; Uchida, Satoshi; Tochikubo, Fumiyoshi; Tokyo Metoropolitan University Team

    2011-10-01

    Non-thermal plasma in and with liquids has attracted considerable interest for its potential use in a wide range of applications. In particular, the use of a discharge with a liquid as an electrode for material processes has been reported. In this study, we focused on atmospheric glow discharge using liquid as anode, and the production of nano-particle by the atmospheric plasma reduction of aqueous cations. When atmospheric dc glow discharge with helium flow was generated, self-organized anode patterns were observed on the liquid. The pattern formation depends on the current, gap length and helium flow rate. With increasing discharge current or gap length, anode luminous spot changed to self-organized patterns. Anode pattern formation depends on the liquid conductivity. When AgNO3 solution is used as liquid anode of the discharge, the liquid changed dark color near the plasma-liquid interface. We confirm the dark region including nano-particle which diameter is about 5-50 nm by TEM observation. The liquid anode discharge reduction of aqueous cations is specific and different from typical electrolysis. The diameter of nano-particle is changed by current, discharge time and addition of surface-active agent to liquid.

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

    NASA Astrophysics Data System (ADS)

    Bogdanov, E. A.; Adams, S. F.; Demidov, V. I.; Kudryavtsev, A. A.; Williamson, J. M.

    2010-10-01

    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.

  1. Atmospheric pressure direct current micro glow discharge simulation: Effects of the external circuit

    NASA Astrophysics Data System (ADS)

    Farouk, Tanvir; Farouk, Bakhtier

    2009-10-01

    The effect of the external circuit on discharge conditions are not explicitly considered in most modeling studies of thermal and non-thermal plasma discharges. In this study, we investigate the effects of including the external circuit on simulation results of atmospheric pressure micro discharges. Two-dimensional simulations of DC atmospheric pressure micro glow discharges were conducted using a hybrid model. The discharge model is coupled to an external circuit model enabling to study the effect of the external circuit parameter. Simulation results were first obtained by excluding the external circuit. When included, the external circuit consisted of a ballast resistance and a parasitic capacitance connected in series and parallel in respect to the discharge. Simulations were conducted over a broad discharge current range (varying ballast resistance) and also for varying parasitic capacitance. For large ballast resistance the discharge was found to operate in the Townsend regime as a dark discharge. At smaller ballast resistance the discharge showed `normal' glow like characteristics. The simulations further indicated that for higher values of the parasitic capacitance the discharge even with a DC power supply was self oscillatory; indicating some unstable regime. The predicted results were found to be in agreement with experimental observations.

  2. Effect of volume and surface charges on discharge structure of glow dielectric barrier discharge

    SciTech Connect

    Xu, Shao-Wei; He, Feng; Wang, Yu; Li, Lulu; Ouyang, Ji-Ting [School of Physics, Beijing Institute of Technology, Beijing 100081 (China)] [School of Physics, Beijing Institute of Technology, Beijing 100081 (China)

    2013-08-15

    The effect of volume and surface charges on the structure of glow dielectric barrier discharge (DBD) has been investigated numerically by using two-dimensional (2D) fluid modeling. The local increase of volume or surface charges induces a kind of activation-inhibition effect, which enhances the local volume discharge and inhibits the discharge in neighborhoods, resulting in non-uniform discharge. The activation-inhibition effect due to the non-uniform volume and/or surface charges depends on the non-uniformity itself and the applied voltage. The activation-inhibition of non-uniform charges has different effects on the volume charges and the accumulated surface charges. The distribution of remaining free charges (seed electrons) in volume at the beginning of voltage pulse plays a key role for the glow DBD structure, resulting in a patterned DBD, when the seed electrons are non-uniform at higher frequency and moderate voltage or uniform DBD, when the seed electrons are uniform at lower frequency or high voltage. The distribution of surface charges is not the determining factor but a result of the formed DBD structure.

  3. Ocular motor abnormalities in neurodegenerative disorders.

    PubMed

    Antoniades, C A; Kennard, C

    2015-02-01

    Eye movements are a source of valuable information to both clinicians and scientists as abnormalities of them frequently act as clues to the localization of a disease process. Classically, they are divided into two main types: those that hold the gaze, keeping images steady on the retina (vestibulo-ocular and optokinetic reflexes) and those that shift gaze and redirect the line of sight to a new object of interest (saccades, vergence, and smooth pursuit). Here we will review some of the major ocular motor abnormalities present in neurodegenerative disorders. PMID:25412716

  4. Hemorheological abnormalities in human arterial hypertension

    NASA Astrophysics Data System (ADS)

    Lo Presti, Rosalia; Hopps, Eugenia; Caimi, Gregorio

    2014-05-01

    Blood rheology is impaired in hypertensive patients. The alteration involves blood and plasma viscosity, and the erythrocyte behaviour is often abnormal. The hemorheological pattern appears to be related to some pathophysiological mechanisms of hypertension and to organ damage, in particular left ventricular hypertrophy and myocardial ischemia. Abnormalities have been observed in erythrocyte membrane fluidity, explored by fluorescence spectroscopy and electron spin resonance. This may be relevant for red cell flow in microvessels and oxygen delivery to tissues. Although blood viscosity is not a direct target of antihypertensive therapy, the rheological properties of blood play a role in the pathophysiology of arterial hypertension and its vascular complications.

  5. Photosensitivity, abnormal porphyrin profile, and sideroblastic anemia.

    PubMed

    Lim, H W; Cooper, D; Sassa, S; Dosik, H; Buchness, M R; Soter, N A

    1992-08-01

    Cutaneous photosensitivity in a 43-year-old man with idiopathic sideroblastic anemia associated with an abnormal porphyrin profile is reported. This condition was associated with elevated free erythrocyte porphyrin, plasma protoporphyrin, urine porphyrins (predominantly coproporphyrin), stool porphyrins (predominantly protoporphyrin), decreased ferrochelatase activity, and deletion of portions of the long arms of chromosomes 18 and 20. Five other patients with sideroblastic anemia and abnormal porphyrin profiles have been described; all but one of these patients had photosensitivity. The porphyrin profile of this patient is similar to that of three other previously described patients. PMID:1517489

  6. LONG-TERM MONITORING OF MODE SWITCHING FOR PSR B0329+54

    SciTech Connect

    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

    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.

  7. Sensory Abnormalities in Autism: A Brief Report

    ERIC Educational Resources Information Center

    Klintwall Lars; Holm, Anette; Eriksson, Mats; Carlsson, Lotta Hoglund; Olsson, Martina Barnevik; Hedvall, Asa; Gillberg, Christopher; Fernell, Elisabeth

    2011-01-01

    Sensory abnormalities were assessed in a population-based group of 208 20-54-month-old children, diagnosed with autism spectrum disorder (ASD) and referred to a specialized habilitation centre for early intervention. The children were subgrouped based upon degree of autistic symptoms and cognitive level by a research team at the centre. Parents…

  8. Kidney Transplantation: The Use of Abnormal Kidneys

    Microsoft Academic Search

    Lauro Branding; Antonio Marcos Arnulf Fraga; Mauro Roberto Rufino Bergonse; Carl Kjellstrand; Anuar Michel Matni; Gilson Lacerda; Pedro Alejandro Gordan; Altair Jacob Mocelin

    1983-01-01

    We transplanted 6 anatomically abnormal kidneys: a horseshoe kidney that after division was transplanted into 2 recipients; 1 kidney with ureteral stones and hydronephrosis; 1 ectopic and 1 hydronephrotic kidney; 2 kidneys with extensive ureteric lesions, donated as free organs. All these kidneys ultimately had normal function in the recipients, long-term in 4. 2 patients died but in neither was

  9. Brain Stem MRI Signal Abnormalities in CADASIL

    Microsoft Academic Search

    H. Chabriat; R. Mrissa; C. Levy; K. Vahedi; H. Taillia; M. T. Iba-Zizen; A. Joutel; E. Tournier-Lasserve; M.-G. Bousser

    Background—We recently showed that the severity of MRI signal abnormalities increases with age in CADASIL, an arteriopathy due to mutations of notch 3 gene on chromosome 19. Previous results also suggest that the various hemispheric subcortical areas have a different vulnerability to ischemia in this disease. The distribution of the lesions at the brain stem level has not yet been

  10. Chromosome abnormalities in Japanese quail embryos

    E-print Network

    Paris-Sud XI, Université de

    Chromosome abnormalities in Japanese quail embryos CA de la Sena NS Fechheimer KE Nestor The Ohio-Auzeville, 10-13 July 1990) Japanese quail / embryos / heteroploidy / chromosomes INTRODUCTION Embryos zygotes and the etiology of heteroploid zygotes and embryos (Fechheimer, 1981, 1990). The Japanese quail

  11. Psychology Faculty Perceptions of Abnormal Psychology Textbooks

    ERIC Educational Resources Information Center

    Rapport, Zachary

    2011-01-01

    The problem. The purpose of the current study was to investigate the perceptions and opinions of psychology professors regarding the accuracy and inclusiveness of abnormal psychology textbooks. It sought answers from psychology professors to the following questions: (1) What are the expectations of the psychology faculty at a private university of…

  12. Some pathological abnormalities of New Zealand fishes

    Microsoft Academic Search

    B. K. Diggles

    2003-01-01

    A number of pathological abnormalities previously unrecorded in New Zealand fishes are described. A silver trevally (Pseudocaranx dentex) captured from the Bay of Islands exhibited swim bladder ectasia. Black oreo (Allocyttus niger) and smooth oreo (Pseudocyttus maculatus) had cysts of unknown aetiology (CUEs) in the gills at prevalences up to 76% and 81%, respectively, in some fishing areas. The CUEs

  13. Emergency Abnormal Conditions 1. Bomb Threat

    E-print Network

    Davis, Lloyd M.

    1 Emergency Abnormal Conditions 1. Bomb Threat a. Bomb threats usually occur by telephone. b. Try OR PACKAGE OR MOVE IT IN ANY WAY! #12;UNIVERSITY OF TENNESSEE SPACE INSTITUTE BOMB THREAT CALL FORM: ___________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ QUESTIONS TO ASK THE CALLER CONCERNING THE BOMB Who are you

  14. Gastric emptying abnormal in duodenal ulcer

    SciTech Connect

    Holt, S.; Heading, R.C.; Taylor, T.V.; Forrest, J.A.; Tothill, P.

    1986-07-01

    To investigate the possibility that an abnormality of gastric emptying exists in duodenal ulcer and to determine if such an abnormality persists after ulcer healing, scintigraphic gastric emptying measurements were undertaken in 16 duodenal ulcer patients before, during, and after therapy with cimetidine; in 12 patients with pernicious anemia, and in 12 control subjects. No difference was detected in the rate or pattern of gastric emptying in duodenal ulcer patients before and after ulcer healing with cimetidine compared with controls, but emptying of the solid component of the test meal was more rapid during treatment with the drug. Comparison of emptying patterns obtained in duodenal ulcer subjects during and after cimetidine treatment with those obtained in pernicious anemia patients and controls revealed a similar relationship that was characterized by a tendency for reduction in the normal differentiation between the emptying of solid and liquid from the stomach. The similarity in emptying patterns in these groups of subjects suggests that gastric emptying of solids may be influenced by changes in the volume of gastric secretion. The failure to detect an abnormality of gastric emptying in duodenal ulcer subjects before and after ulcer healing calls into question the widespread belief that abnormally rapid gastric emptying is a feature with pathogenetic significance in duodenal ulcer disease.

  15. Abnormally high formation pressures, Potwar Plateau, Pakistan

    USGS Publications Warehouse

    Law, B.E.; Shah, S.H.A.; Malik, M.A.

    1998-01-01

    Abnormally high formation pressures in the Potwar Plateau of north-central Pakistan are major obstacles to oil and gas exploration. Severe drilling problems associated with high pressures have, in some cases, prevented adequate evaluation of reservoirs and significantly increased drilling costs. Previous investigations of abnormal pressure in the Potwar Plateau have only identified abnormal pressures in Neogene rocks. We have identified two distinct pressure regimes in this Himalayan foreland fold and thrust belt basin: one in Neogene rocks and another in pre-Neogene rocks. Pore pressures in Neogene rocks are as high as lithostatic and are interpreted to be due to tectonic compression and compaction disequilibrium associated with high rates of sedimentation. Pore pressure gradients in pre-Neogene rocks are generally less than those in Neogene rocks, commonly ranging from 0.5 to 0.7 psi/ft (11.3 to 15.8 kPa/m) and are most likely due to a combination of tectonic compression and hydrocarbon generation. The top of abnormally high pressure is highly variable and doesn't appear to be related to any specific lithologic seal. Consequently, attempts to predict the depth to the top of overpressure prior to drilling are precluded.

  16. Renal abnormalities in sickle cell disease

    Microsoft Academic Search

    Phuong-Thu T Pham; Phuong-Chi T Pham; Alan H Wilkinson; Susie Q Lew

    2000-01-01

    Renal abnormalities in sickle cell disease. Sickle cell nephropathy is indicated by sickled erythrocytes, with the consequent effects of decreased medullary blood flow, ischemia, microinfarct and papillary necrosis. Impaired urinary concentrating ability, renal acidification, hematuria, and potassium secretion are also found. There may be a causal relationship between an increase in nitric oxide synthesis and experimental sickle cell nephropathy, and

  17. On (ab)normality: Einstein's fusiform gyrus.

    PubMed

    Weiner, Kevin S

    2015-03-01

    Recently, Hines (2014) wrote an evocative paper challenging findings from both histological and morphological studies of Einstein's brain. In this discussion paper, I extend Hines' theoretical point and further discuss how best to determine 'abnormal' morphology. To do so, I assess the sulcal patterning of Einstein's fusiform gyrus (FG) for the first time. The sulcal patterning of the FG was unconsidered in prior studies because the morphological features of the mid-fusiform sulcus have only been clarified recently. On the one hand, the sulcal patterning of Einstein's FG is abnormal relative to averages of 'normal' brains generated from two independent datasets (N = 39 and N = 15, respectively). On the other hand, within the 108 hemispheres used to make these average brains, it is not impossible to find FG sulcal patterns that resemble those of Einstein. Thus, concluding whether a morphological pattern is normal or abnormal heavily depends on the chosen analysis method (e.g. group average vs. individual). Such findings question the functional meaning of morphological 'abnormalities' when determined by comparing an individual to an average brain or average frequency characteristics. These observations are not only important for analyzing a rare brain such as that of Einstein, but also for comparing macroanatomical features between typical and atypical populations. PMID:25562419

  18. The physics and phenomenology of One Atmosphere Uniform Glow Discharge Plasma (OAUGDP™) reactors for surface treatment applications

    Microsoft Academic Search

    J. Reece Roth; Jozef Rahel; Xin Dai; Daniel M. Sherman

    2005-01-01

    In this paper, we present data on the physics and phenomenology of plasma reactors based on the One Atmosphere Uniform Glow Discharge Plasma (OAUGDP™) that are useful in optimizing the conditions for plasma formation, uniformity and surface treatment applications. It is shown that the real (as opposed to reactive) power delivered to a reactor is divided between dielectric heating of

  19. Collisional–radiative model for the sputtered copper atoms and ions in a direct current argon glow discharge

    Microsoft Academic Search

    Annemie Bogaerts; Renaat Gijbels; Robert J. Carman

    1998-01-01

    A collisional–radiative model is developed for various levels of the sputtered copper (Cu) atoms and their ions in an argon (Ar) direct current glow discharge, used as an analytical source for optical emission spectrometry. In this application, attention is paid to the photons emitted by sputtered atoms and ions, and hence to the behavior of excited levels of these species.

  20. Non-intrusive measurement of axial electric fields in low-pressure glow discharges by velocity modulation laser spectroscopy

    Microsoft Academic Search

    Michael B. RADUNSKY; Richard J. SAYKALLY

    1988-01-01

    High resolution (Doppler-resolved) measurement of Doppler-shifted ion absorption frequencies allows the determination of the electric field responsible for the shift. A new method based on velocity modulation laser spectroscopy is described for the non- perturbative measurement of the axial electric fields in glow discharges. The A 'n, + X I&+ (4.0 ) band of NT has heen used as a

  1. Absorption spectroscopic studies of carbon dioxide conversion in a low pressure glow discharge using tunable infrared diode lasers

    Microsoft Academic Search

    F. Hempel; J. Röpcke; F. Miethke; H.-E. Wagner

    2002-01-01

    The time and spatial dependence of the chemical conversion of CO2 to CO were studied in a closed glow discharge reactor (p = 50 Pa, I = 2-30 mA) consisting of a small plasma zone and an extended stationary afterglow. Tunable infrared diode laser absorption spectroscopy has been applied to determine the absolute ground state concentrations of CO and CO2.

  2. Temporal and spatially resolved laser-scattering plasma diagnostics for the characterization of a ms-pulsed glow discharge

    Microsoft Academic Search

    Gerardo Gamez; Annemie Bogaertsb; Gary M. Hieftje

    2006-01-01

    A previously described instrument was used to obtain axial profiles of the gas-kinetic temperature (Tg) in a ms-pulsed glow discharge via Rayleigh scattering. In addition, the electron number density (ne) and the electron temperature (Te) were observed via Thomson scattering. For these measurements, the detection optics of the original instrument were modified and a photon- counting imaging technique was employed

  3. Influence of the unstable glow discharge plasma state on the CW CO[sub 2] laser output

    SciTech Connect

    Tsui, K.H.; Zanon, R.A.D.; Massone, C.A. (Univ. Federal Fluminense, Rio de Janiero (Brazil))

    1993-07-01

    The recently reported high nitrogen partial pressure CW CO[sub 2] laser regime which operates without auxiliary cooling is extended to the high-nitrogen high-helium partial pressure regime with an output power one order of magnitude above the former one. Both regimes rely on an unstable glow discharge plasma with extended electrodes that presents nonperiodic voltage spikes.

  4. Depth profile analysis of layered samples using glow discharge assisted Laser-induced Breakdown Spectrometry (GD-LIBS)

    Microsoft Academic Search

    K. A. Tereszchuk; J. M. Vadillo; J. J. Laserna

    2009-01-01

    A microsecond-pulsed glow discharge is used to excite ablate material generated by the ablation laser in Laser-induced Breakdown Spectrometry (LIBS). The coupled system provides a simple means to excite the material ablated by the incident laser pulse by taking advantage of enhanced collisional excitation. In this way, one can effectively reduce laser energies below the excitation and ionization thresholds to

  5. ACTIVE MEDIA: Atomic iodine production in a gas flow by decomposing methyl iodide in a dc glow discharge

    Microsoft Academic Search

    P. A. Mikheyev; A. A. Shepelenko; A. I. Voronov; Nikolai V. Kupryaev

    2002-01-01

    The production of atomic iodine for an oxygen --- iodine laser is studied by decomposing methyl iodide in a dc glow discharge in a vortex gas flow. The concentration of iodine atoms in discharge products was measured from the atomic iodine absorption of the radiation of a single-frequency tunable diode laser at a wavelength of 1.315 mum. Atomic iodine concentrations

  6. Strong pattern selection and amplitude equation of higher order for ionization waves in a neon glow discharge

    Microsoft Academic Search

    B. Bruhn; B.-P. Koch

    2000-01-01

    Motivated by recent experiments and numerical simulations of the positive column of a neon glow discharge we investigate the Eckhaus instability of traveling waves. Compared to the classical results the plasma system shows some peculiarities, e.g., an asymmetric stability region and strong selection of periodic patterns. These complex phenomena may be explained by a transition from supercritical to subcritical Hopf

  7. Monte Carlo analysis of the electron thermalization process in the afterglow of a microsecond dc pulsed glow discharge

    Microsoft Academic Search

    A. Martin; N. Bordel; R. Pereiro; A. Bogaerts

    2008-01-01

    A Monte Carlo model is utilized for studying the behavior of electrons in the afterglow of an analytical microsecond dc pulsed glow discharge. This model uses several quantities as input data, such as electric field and potential, ion flux at the cathode, the fast argon ion and atom impact ionization rates, slow electron density, the electrical characterization of the pulse

  8. ‘Ebony Embers’, ‘Ebony Fire’, ‘Ebony Flame’, ‘Ebony Glow’ and ‘Ebony and Ivory’ Five New Dark-leaved Crape Myrtles

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ebony Embers’, ‘Ebony Fire’, ‘Ebony Flame’, ‘Ebony Glow’ and ‘Ebony and Ivory’ are cultivars which are predominantly L. indica in heritage that combine persistent black-purple leaves and a range of flower colors with intermediate growth habits. ‘Ebony Embers’ has a vase shaped growth habit with dime...

  9. 'Ebony Embers', 'Ebony Fire', 'Ebony Flame','Ebony Glow' and 'Ebony and Ivory' Dark-Leaf Crapemyrtles

    Technology Transfer Automated Retrieval System (TEKTRAN)

    ‘Ebony Embers’, ‘Ebony Fire’, ‘Ebony Flame’, ‘Ebony Glow’ and ‘Ebony and Ivory’ are cultivars which are predominantly L. indica in heritage that combine persistent black-purple leaves and a range of flower colors with intermediate growth habits. ‘Ebony Embers’ has a vase shaped growth habit with dim...

  10. In eastern North America, the glow of a sugar maple-covered hillside in full autumn color is an unforgettable

    E-print Network

    Weathers, Kathleen C.

    In eastern North America, the glow of a sugar maple- covered hillside in full autumn color is an unforgettable sight. Sugar maple (Acer saccharum) (Figure 1) is one of several major tree species of its range (southern Ontario and Quebec, New England and New York) sugar maple is often the domi- nant

  11. A model of the cathode spot glow discharge for a cathode with inclusions of low work function material

    Microsoft Academic Search

    Leonid Pekker

    1993-01-01

    A model that describes the self-maintained glow discharge for a composite cathode in which cathode spots are formed on low work function material inclusions is presented. Based on this model, expressions are obtained for the radius of the spot, the cathode voltage, and the spot current as functions of Pd (where P is the gas pressure and d is the

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

    Microsoft Academic Search

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

    2007-01-01

    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

  13. Glowing Flowers

    NSDL National Science Digital Library

    Integrated Teaching and Learning Program,

    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 — unlike dyes that can only be seen in visible light.

  14. Glow Up

    NSDL National Science Digital Library

    Julie Yu

    2008-01-01

    In this activity, learners explore chemiluminescence and fluorescence. Learners examine 3 different solutions in regular light, in the dark with added bleach solution, and under a black light. This resource includes information about chemiluminescence and fluorescence including how these properties pertain to molecular and cell biology.

  15. Application of Radio-Frequency Plasma Glow Discharge to Removal of Uranium Dioxide from Metal Surfaces

    SciTech Connect

    El-Genk, Mohamed S.; Saber, Hamed H. [University of New Mexico (United States)

    2000-11-15

    Recent experiments have shown that radio-frequency (rf) plasma glow discharge using NF{sub 3} gas is an effective technique for the removal of uranium oxide from metal surfaces. The results of these experiments are analyzed to explain the measured dependence of the UO{sub 2} removal or etch rate on the NF{sub 3} gas pressure and the absorbed power in the plasma. The NF{sub 3} gas pressure in the experiments was varied from 10.8 to 40 Pa, and the deposited power in the plasma was varied from 25 to 210 W. The UO{sub 2} etch rate was strongly dependent on the absorbed power and, to a lesser extent, on the NF{sub 3} pressure and decreased exponentially with immersion time. At 210 W and 17 Pa, all detectable UO{sub 2} in the samples ({approx}10.6 mg each) was removed at the endpoint, whereas the initial etch rate was {approx}3.11 {mu}m/min. When the absorbed power was {<=}50 W, however, the etch rate was initially {approx}0.5 {mu}g/min and almost zero at the endpoint, with UO{sub 2} only partially etched. This self-limiting etching of UO{sub 2} at low power is attributed to the formation of nonvolatile intermediates UF{sub 2}, UF{sub 3}, UF{sub 4}, UF{sub 5}, UO{sub 2}F, and UO{sub 2}F{sub 2} on the surface. Analysis indicated that the accumulation of UF{sub 6} and, to a lesser extent, O{sub 2} near the surface partially contributed to the exponential decrease in the UO{sub 2} etch rate with immersion time. Unlike fluorination with F{sub 2} gas, etching of UO{sub 2} using rf glow discharge is possible below 663 K. The average etch rates of the amorphous UO{sub 2} in the NF{sub 3} experiments are comparable to the peak values reported in other studies for crystalline UO{sub 2} using CF{sub 4}/O{sub 2} glow discharge performed at {approx}150 to 250 K higher sample temperatures.

  16. A novel Ir-Zr gradient coating prepared on Mo substrate by double glow plasma

    NASA Astrophysics Data System (ADS)

    Cong, Xiangna; Chen, Zhaofeng; Wu, Wangping; Xu, Jiang; Boafo, Fred Edmond

    2012-04-01

    Ir-Zr gradient coating was obtained on the Mo substrate by double glow plasma. The structure and composition of the coatings were confirmed by SEM, AFM, XRD and EDS, respectively. The adhesion strength between the coating and the substrate was evaluated by a scratch tester. Compared with preferential growth orientation of (2 2 0) crystal plane of Ir coating, the Ir-Zr coating had a random orientation structure. The RMS roughness value of the Ir-Zr coating is 19.3 nm, which was lower than the roughness value of 45 nm for Ir coating. The Ir-Zr coating with the thickness of 5.0 ?m was composed of two distinct layers. The proportion of Ir decreased gradually from the surface of the coating to the coating/substrate interface. The Zr distribution decreased slightly in the coating. The adhesive force of the Ir-Zr coating was 15 N.

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

    SciTech Connect

    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

    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.

  18. Experimental And Theoretical Studies On The Characteristics Of Low-Pressure Glow Discharge With Liquid Cathode

    NASA Astrophysics Data System (ADS)

    Shutov, D.; Ivanov, A.; Smirnov, S.; Rybkin v.

    2010-07-01

    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.

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

    PubMed

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

    2013-01-01

    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

  20. UV-VUV excimer emitter pumped by a subnormal glow discharge

    SciTech Connect

    Shuaibov, Aleksandr K; Dashchenko, Arkadii I; Shevera, Igor' V [Uzhgorod National University, Uzhgorod (Ukraine)

    2001-04-30

    Characteristics of a small-size excimer emitter operating on an Ar - Cl{sub 2} mixture excited by a subnormal glow discharge are studied. It is shown that this discharge is a source of multiwavelength emission in a range of 175 - 258 nm. The optimum pressures lie in ranges of 0.3 - 0.5 kPa for chlorine and 2 - 4 kPa for argon. The average power of UV- VUV emission reaches 0.7 W, with the emission efficiency equal to 3 %. The emitter can be used in microelectronics, high-energy chemistry, short-wavelength photometry, biophysics, and medicine. (laser applications and other topics in quantum electronics)

  1. Isotopic analysis of uranium using glow discharge optogalvanic spectroscopy and diode lasers

    SciTech Connect

    Barshick, C.M.; Shaw, R.W.; Young, J.P.; Ramsey, J.M. (Oak Ridge National Lab., TN (United States))

    1994-12-01

    A hollow cathode glow discharge has been coupled with tunable lasers for isotopically selective excitation of gaseous uranium atoms produced by cathodic sputtering. A CW argon ion laser-pumped titanium:sapphire ring laser and a semiconductor diode laser were employed. Optogalvanic detection of the discharge atom population allowed identification of [sup 235]U at depleted, natural, and enriched abundances in uranium metal and uranium oxide samples based on the spectral signatures of two transitions. Isotope ratio measurements were precise from run to run (internal precision) to better than +1% relative standard deviation at 1[sigma]; external precision (sample to sample) was on the order of [+-]3% relative standard deviation at 1[sigma]. As in mass spectrometry, the most accurate analysis will be obtained when a bias correction is employed to correct for day to day variations in the laser and discharge conditions. 24 refs., 4 figs., 1 tab.

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

    SciTech Connect

    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

    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.

  3. Comparative Study of Electric Field Measurement in Glow Discharges using Laser Optogalvanic Spectroscopy

    SciTech Connect

    Hussain, Shahid [National Tokamak Fusion Program P.O. Box 3329 Islamabad Pakistan (Pakistan); Saleem, M. [Optics Laboratory PINSTECH Nilore Islamabad (Pakistan); Baig, M. A. [Atomic and Molecular Physics Laboratory, Department of Physics, Quaid-i-Azam University, Islamabad 45320 (Pakistan)

    2008-10-22

    The net electric field inside low-pressure glow discharges has been measured using laser optogalvanic spectroscopy of 1s2s {sup 1}S{sub 0}{yields}np{sup 1}P{sub 1} Rydberg series of atomic helium. Three different types of discharges, an inductively coupled RF discharge cell operating at 4 MHz, a homemade DC discharge cell and a commercial see-through hollow cathode lamp have been used for these studies. The Rydberg series terminates earlier in the high electric field discharge as compared to that in the low electric field discharge. The net electric field also produces shift and broadens the observed spectral lines especially in the high lying Rydberg transitions. The electric field has been determined from the series termination and also from the energy shift of the observed transitions.

  4. Cd-Ne direct current glow discharge: An efficient source of ultraviolet radiation

    NASA Astrophysics Data System (ADS)

    Petrov, G. M.; Petrova, Ts.; Ogoyski, A.; Blagoev, A. B.

    2000-07-01

    This investigation aims to present data of a potential light source based on Cd. Recent study of cadmium-neon direct current glow discharge at low and intermediate pressure showed that a significant fraction (˜80%) of the input power delivered to the plasma can be converted into resonance radiation, which leads us to conclusion that Cd can be an efficient light source, even more efficient than Hg. The conventional fluorescent lamps contain Hg, but environmental concerns urge for mercury-free light sources. The ultraviolet radiation from Cd(5p1P1) and Cd(5p3P1) resonance states has been investigated and the optimum discharge conditions of a potential light source are determined. At optimum discharge conditions 80%-87% of the input power is converted into resonance radiation.

  5. Heterodyne detection at 300 GHz using neon indicator lamp glow discharge detector.

    PubMed

    Aharon Akram, Avihai; Rozban, Daniel; Kopeika, Natan S; Abramovich, Amir

    2013-06-10

    A miniature neon indicator lamp, also known as a glow discharge detector (GDD), costing about 50 cents, was found to be an excellent room temperature terahertz radiation detector. Proof-of-concept 300 GHz heterodyne detection using GDD is demonstrated in this paper. Furthermore, a comparison to direct detection was carried out as well. Previous results with the GDD at 10 GHz showed 40 times better sensitivity using heterodyne detection compared to direct detection. Preliminary results at 300 GHz showed better sensitivity by a factor of 20 with only 56 ?W local-oscillator power using heterodyne compared to direct detection. The higher the local-oscillator power (P(lo)), the better the sensitivity of the detector. Further improvement can be achieved by employing better quasi-optical design. PMID:23759859

  6. A study of the glow discharge characteristics of contact electrodes at atmospheric pressure in air

    SciTech Connect

    Liu, Wenzheng, E-mail: wzhliu@bjtu.edu.cn; Sun, Guangliang, E-mail: 11121659@bjtu.edu.cn; Li, Chuanhui; Zhang, Rongrong [School of Electrical Engineering, Beijing Jiaotong University, Beijing 100044 (China)] [School of Electrical Engineering, Beijing Jiaotong University, Beijing 100044 (China)

    2014-04-15

    Electric field distributions and discharge properties of rod-rod contact electrodes were studied under the condition of DBD for the steady generation of atmospheric pressure glow discharge plasma (APGD) in air. We found that under the effect of the initial electrons generated in a nanometer-scale gap, the rod-rod cross-contact electrodes yielded APGD plasma in air. Regarding the rod-rod cross-contact electrodes, increasing the working voltage expanded the strong electric field area of the gas gap so that both discharge area and discharge power increased, and the increase in the number of contact points kept the initial discharge voltage unchanged and caused an increase in the plasma discharge area and discharge power. A mesh-like structure of cross-contact electrodes was designed and used to generate more APGD plasma, suggesting high applicability.

  7. Effect of metastable neon atoms in a positive column of glow discharge with dust particles

    NASA Astrophysics Data System (ADS)

    Shumova, V. V.; Polyakov, D. N.; Vasilyak, L. M.

    2014-12-01

    The diffusion/drift model of the positive column of glow discharge in neon was used for the analysis of the role of neon metastable atoms in the interaction between neon plasma and dust particles. The radial profiles of electrons and metastable atoms were simulated in the typical range of neon pressure and discharge current where dust particles may form dense dust structures changing the plasma properties. The results showed the nonlocal effect of dust particles on the plasma composition. Within the dust structure, the metastable atom concentration was shown to be higher than in the discharge without dust particles at the same discharge parameters; the ratio of concentrations of metastable atoms and electrons may increase with increasing dust particle concentration in a certain range of discharge parameters. The partial contribution of metastable atoms to the ionization was found to be higher than their losses on the surface of dust particles and increased when the gas pressure was increased.

  8. Study of hydrogenated amorphous silicon deposited by rf glow discharge in silane-hydrogen mixtures

    SciTech Connect

    Vanier, P.E.; Kampas, F.J.; Corderman, R.R.; Rajeswaran, G.

    1984-09-15

    The rf glow discharge deposition of hydrogenated amorphous silicon from silane-hydrogen mixtures has been studied as a function of silane fraction. Discharge processes were investigated using optical emission spectroscopy and mass spectrometry. The deposited films were characterized using UV and IR spectroscopy, dark conductivity, and photoconductivity. The dilution of silane in hydrogen resulted in an increase in deposition rate by as much as an order of magnitude over the rate for pure silane, for constant values of total flow rate, pressure, substrate temperature, and rf power. The dependence of deposition rate on silane fraction is attributed to changes in the electron energy distribution in the plasma. The hydrogen content and optical gap of the films are independent of the silane fraction. Photoconductivity values, corrected for slight variations of the Fermi level, increase with silane dilution.

  9. Photoelectronic properties of hydrogenated amorphous silicon films deposited by R. F sputtering and glow discharge methods

    SciTech Connect

    Abdel-Rahman, M.; Madkour, H. (Faculty of Science, Aswan (Egypt)); Hassan, H.H.; El-Desouki, S. (Cairo Univ., Giza (Egypt))

    1989-09-01

    Hydrogenated amorphous silicon films a-Si:H were deposited by both R.F. sputtering in a planar magnetron configuration and glow discharge methods on Corning glass substrates at different substrate temperatures. The dc and ac photoconductivities of the deposited films were extensively studied as a function of temperature, photon energy and photo-excitation intensity. The results showed that, the dark and photoconductivities have different dependency regions on temperature with different activation energies in the range of 0.08-0.20 eV. It has been also found that the photoconductivity is influenced by the method of deposition and the deposition parameters, indicating that the density of gap states is sensitive to the deposition conditions. The photoconductivity ({sigma}{sub ph}) has a power dependence on the illumination intensity (I) of the form {sigma}{sub ph} {alpha} I {sup {nu}}, where {nu} is a constant and was found also to be increase with temperature.

  10. High deposition rate preparation of amorphous silicon solar cells by rf glow discharge decomposition of disilane

    SciTech Connect

    Kenne, J.; Ohashi, Y.; Matsushita, T.; Konagai, M.; Takahashi, K.

    1984-01-15

    The optical and electrical properties of hydrogenated amorphous silicon films produced by rf glow discharge decomposition of disilane diluted in helium (Si/sub 2/H/sub 6//He = 1/9) have been studied while systematically varying the film deposition rate. The properties and composition of the films were monitored by measuring the optical band gap, IR vibrational spectrum, dark conductivity, and the photoconductivity as a function of the deposition rate. The photoluminescence of the high deposition rate films gave a peak at 1.33 eV. These films, whose properties are rather similar to those of the conventional a-Si:H films prepared from monosilane, have been used to fabricate nip-type a-Si:H solar cells. At a deposition rate of 11 A/sec, a conversion efficiency of 6.86% was obtained. This high efficiency shows that disilane is applicable for mass production fabrication of a-Si:H solar cells.

  11. Analysis of glow discharges for understanding the process of film formation

    NASA Technical Reports Server (NTRS)

    Venugopalan, M.; Avni, R.

    1984-01-01

    The physical and chemical processes which occur during the formation of different types of films in a variety of glow discharge plasmas are discussed. Emphasis is placed on plasma diagnostic experiments using spectroscopic methods, probe analysis, mass spectrometric sampling and magnetic resonance techniques which are well suited to investigate the neutral and ionized gas phase species as well as some aspects of plasma surface interactions. The results on metallic, semi-conducting and insulating films are reviewed in conjunction with proposed models and the problem encountered under film deposition conditions. It is concluded that the understanding of film deposition process requires additional experimental information on plasma surface interactions of free radicals and the synergetic effects where photon, electron and ion bombardment change the reactivity of the incident radical with the surface.

  12. Diamond-like carbon coating and plasma or glow discharge treatment of mechanical heart valves.

    PubMed

    Tran, H S; Puc, M M; Hewitt, C W; Soll, D B; Marra, S W; Simonetti, V A; Cilley, J H; DelRossi, A J

    1999-01-01

    All mechanical heart valves (MHV) are thrombogenic. Application of surface modification technology to reduce the incidence of thrombus formation on MHV is a novel undertaking. This requires collaboration within the bioengineering and cardiothoracic surgery fields. From reviewing results of recent and past investigations, and our own preliminary study with diamond-like carbon coating (DLC) and plasma or glow discharge treatment (GDT) of MHV, we identify and discuss several potentially beneficial effects that may reduce the extent of valve-related thrombogenesis by surface modification. DLC and GDT may affect the surfaces of MHV in many ways, including cleaning of organic and inorganic debris, generating reactive and functional groups on the surface layers without affecting their bulk properties, and making the surfaces more adherent to endothelial cells and albumin and less adherent to platelets. These different effects of surface modification, separately or in combination, may transform the surfaces of MHV to be more thromboresistant in the vascular system. PMID:10421514

  13. Room temperature sterilization of surfaces and fabrics with a one atmosphere uniform glow discharge plasma.

    PubMed

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

    1998-01-01

    We report the results of an interdisciplinary collaboration formed to assess the sterilizing capabilities of the One Atmosphere Uniform Glow Discharge Plasma (OAUGDP). This newly-invented source of glow discharge plasma (the fourth state of matter) is capable of operating at atmospheric pressure in air and other gases, and of providing antimicrobial active species to surfaces and workpieces at room temperature as judged by viable plate counts. OAUGDP exposures have reduced log numbers of bacteria, Staphylococcus aureus and Escherichia coli, and endospores from Bacillus stearothermophilus and Bacillus subtilis on seeded solid surfaces, fabrics, filter paper, and powdered culture media at room temperature. Initial experimental data showed a two-log10 CFU reduction of bacteria when 2 x 10(2) cells were seeded on filter paper. Results showed > or = 3 log10 CFU reduction when polypropylene samples seeded with E. coli (5 x 10(4)) were exposed, while a 30 s exposure time was required for similar killing with S. aureus-seeded polypropylene samples. The exposure times required to effect > or = 6 log10 CFU reduction of E. coli and S. aureus on polypropylene samples were no longer than 30 s. Experiments with seeded samples in sealed commercial sterilization bags showed little or no differences in exposure times compared to unwrapped samples. Plasma exposure times of less than 5 min generated > or = 5 log10 CFU reduction of commercially prepared Bacillus subtilis spores (1 x 10(5)); 7 min OAUGDP exposures were required to generate a > or = 3 log10 CFU reduction for Bacillus stearothermophilus spores. For all microorganisms tested, a biphasic curve was generated when the number of survivors vs time was plotted in dose-response cures. Several proposed mechanisms of killing at room temperature by the OAUGDP are discussed. PMID:9523458

  14. Alteration of five organic compounds by glow discharge plasma and UV light under simulated Mars conditions

    NASA Astrophysics Data System (ADS)

    Hintze, Paul E.; Buhler, Charles R.; Schuerger, Andrew C.; Calle, Luz M.; Calle, Carlos I.

    2010-08-01

    The Viking missions to Mars failed to detect any organic material in regolith samples. Since then, several removal mechanisms of organic material have been proposed. Two of these proposed methods are removal due to exposure to plasmas created in dust devils and exposure to UV irradiation. The experiments presented here were performed to identify similarities between the two potential removal mechanisms and to identify any compounds produced from these mechanisms that would have been difficult for the Viking instruments to detect. Five organic compounds, phenanthrene, octadecane, octadecanoic acid, decanophenone and benzoic acid, were exposed to a glow discharge plasma created in simulated martian atmospheres as might be present in dust devils, and to UV irradiation similar to that found at the surface of Mars. Glow discharge exposure was carried out in a chamber with 6.9 mbar pressure of a Mars like gas composed mostly of carbon dioxide. The plasma was characterized using emission spectroscopy and found to contain cations and excited neutral species including carbon dioxide, carbon monoxide, and nitrogen. UV irradiation experiments were performed in a Mars chamber which simulates the temperature, pressure, atmospheric composition, and UV fluence rates of equatorial Mars. The non-volatile residues left after each exposure were characterized by mass loss, infrared spectroscopy and high resolution mass spectrometry. Oxidized, higher molecular weight versions of the parent compounds containing carbonyl, hydroxyl and alkenyl functional groups were identified. The presence of these oxidized compounds suggests that searches for organic material in soils on Mars use instrumentation suitable for detection of compounds which contain the above functional groups. Discussions of possible reaction mechanisms are given.

  15. Decomposition of toluene in a steady-state atmospheric-pressure glow discharge

    SciTech Connect

    Trushkin, A. N.; Grushin, M. E.; Kochetov, I. V.; Trushkin, N. I.; Akishev, Yu. S. [Troitsk Institute for Innovation and Fusion Research (Russian Federation)] [Troitsk Institute for Innovation and Fusion Research (Russian Federation)

    2013-02-15

    Results are presented from experimental studies of decomposition of toluene (C{sub 6}H{sub 5}CH{sub 3}) in a polluted air flow by means of a steady-state atmospheric pressure glow discharge at different water vapor contents in the working gas. The experimental results on the degree of C{sub 6}H{sub 5}CH{sub 3} removal are compared with the results of computer simulations conducted in the framework of the developed kinetic model of plasma chemical decomposition of toluene in the N{sub 2}: O{sub 2}: H{sub 2}O gas mixture. A substantial influence of the gas flow humidity on toluene decomposition in the atmospheric pressure glow discharge is demonstrated. The main mechanisms of the influence of humidity on C{sub 6}H{sub 5}CH{sub 3} decomposition are determined. The existence of two stages in the process of toluene removal, which differ in their duration and the intensity of plasma chemical decomposition of C{sub 6}H{sub 5}CH{sub 3} is established. Based on the results of computer simulations, the composition of the products of plasma chemical reactions at the output of the reactor is analyzed as a function of the specific energy deposition and gas flow humidity. The existence of a catalytic cycle in which hydroxyl radical OH acts a catalyst and which substantially accelerates the recombination of oxygen atoms and suppression of ozone generation when the plasma-forming gas contains water vapor is established.

  16. Behavioral correlates of epileptiform abnormalities in autism.

    PubMed

    Trauner, Doris A

    2014-11-01

    There is a high incidence of epileptiform abnormalities in children with autism even in the absence of clinical seizures. These findings are most prominent during sleep recordings. The significance of these abnormalities is unclear. Although studies do not all agree, there may be some association between cognitive function, behavior, and the presence or absence of epileptiform discharges. Small studies of anticonvulsant treatment mostly suggest an improvement in certain aspects of cognitive or behavioral functioning in these children, but larger and more comprehensive studies are needed to determine the potential relationship between epileptiform discharges on EEG, cognitive and behavioral functioning, and treatment effects in the population with autism. This article is part of a Special Issue entitled "Autism and Epilepsy". PMID:25453621

  17. Developmental pragmatics in normal and abnormal children.

    PubMed

    Bara, B G; Bosco, F M; Bucciarelli, M

    1999-07-01

    We propose a critical review of current theories of developmental pragmatics. The underlying assumption is that such a theory ought to account for both normal and abnormal development. From a clinical point of view, we are concerned with the effects of brain damage on the emergence of pragmatic competence. In particular, the paper deals with direct speech acts, indirect speech acts, irony, and deceit in children with head injury, closed head injury, hydrocephalus, focal brain damage, and autism. Since no single theory covers systematically the emergence of pragmatic capacity in normal children, it is not surprising that we have not found a systematic account of deficits in the communicative performance of brain injured children. In our view, the challenge for a pragmatic theory is the determination of the normal developmental pattern within which different pragmatic phenomena may find a precise role. Such a framework of normal behavior would then permit the systematic study of abnormal pragmatic development. PMID:10441191

  18. Abnormalities in signaling pathways in diabetic nephropathy

    PubMed Central

    Brosius, Frank C; Khoury, Charbel C; Buller, Carolyn L; Chen, Sheldon

    2010-01-01

    Diabetic nephropathy (DN) is characterized by a plethora of signaling abnormalities that together ultimately result in the clinical and pathologic hallmarks of DN, namely progressive albuminuria followed by a gradual decline in glomerular filtration rate leading to kidney failure, and accompanied by podocyte loss, progressive glomerular sclerosis and, ultimately, progressive tubulointerstitial fibrosis. Over the past few years, the general understanding of the abnormalities in signaling pathways that lead to DN has expanded considerably. In this review, some of the important pathways that appear to be involved in driving this process are discussed, with special emphasis on newer findings and insights. Newer concepts regarding signaling changes in bradykinin, mTOR, JAK/STAT, MCP-1, VEGF, endothelial nitric oxide synthase, activated protein C and other pathways are discussed. PMID:20224802

  19. Abnormalities of the foetal cerebral cortex.

    PubMed

    Toi, Ants; Chitayat, David; Blaser, Susan

    2009-04-01

    Prenatal ultrasound has concentrated on readily visible cerebral structures including head size, shape, ventricles, CSP (cavum septi pellucidi), cerebellar size/vermian presence and cisterna magna. However, apart from these easily visible structures it is important to evaluate the brain itself. Patients who initially appear to have mild isolated findings such as borderline ventriculomegaly in fact can have many more subtle findings that significantly alter prognosis and management that can be detected on detailed examination of the brain. There has been rapid evolution in imaging these foetuses, especially with neurosonography and MRI, and a revolution in understanding the underlying genetic and biochemical mechanisms. There is increasing emphasis to detect cortical abnormalities as early as possible. This article reviews development of the cerebral cortex, the classification, aetiologies and clinical manifestations of cortical disorders, normal and abnormal appearances at ultrasound and MRI, and approaches to investigation. PMID:19235759

  20. Chromosomal abnormalities in a psychiatric population

    SciTech Connect

    Lewis, K.E.; Lubetsky, M.J.; Wenger, S.L.; Steele, M.W. [Univ. of Pittsburgh Medical Center, PA (United States)

    1995-02-27

    Over a 3.5 year period of time, 345 patients hospitalized for psychiatric problems were evaluated cytogenetically. The patient population included 76% males and 94% children with a mean age of 12 years. The criteria for testing was an undiagnosed etiology for mental retardation and/or autism. Cytogenetic studies identified 11, or 3%, with abnormal karyotypes, including 4 fragile X positive individuals (2 males, 2 females), and 8 with chromosomal aneuploidy, rearrangements, or deletions. While individuals with chromosomal abnormalities do not demonstrate specific behavioral, psychiatric, or developmental problems relative to other psychiatric patients, our results demonstrate the need for an increased awareness to order chromosomal analysis and fragile X testing in those individuals who have combinations of behavioral/psychiatric, learning, communication, or cognitive disturbance. 5 refs., 1 fig., 2 tabs.