Cold starting of fluorescent lamps - part II: experiments on glow times and electrode damaging

NASA Astrophysics Data System (ADS)

Langer, Reinhard; Paul, Irina; Hilscher, Achim; Horn, Siegfried; Tidecks, Reinhard

2017-01-01

In the present work we present experiments on cold start and the resulting electrode damaging (reducing lamp life) of AC driven fluorescent lamps. The crucial parameter is the glow time, determined from time resolved measurements of lamp voltage and current. The relation between the energy consumed during glow phase and the glow time is studied. It turns out that there is no common threshold of energy until the glow-to-arc transition takes place, but strong energy input into the lamp yields short glow times. The transient behaviour from the glow to the arc regime is investigated and the stable operation points of the arc discharge are determined, yielding an arc discharge voltage-current characteristics of the lamp type investigated. The electrode damage is investigated as a function of the open source voltage and the ballast resistance. Subsequent cold starts lead to an increase of the glow time due to electrode damaging, i.e., the electrode damage accumulates. Different regeneration procedures and their effectiveness are compared. Regeneration burning turns out to be more effective than heating up the electrode. A criterion for avoiding high electrode damage is obtained, indicating that the average power during glow time should exceed 20 W.

Formation of a spark discharge in an inhomogeneous electric field with current limitation by a large ballast Resistance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baldanov, B. B., E-mail: baibat@mail.ru

2016-01-15

Results of studies of a spark discharge initiated in argon in a point–plane electrode gap with limitation of the discharge current by a large ballast resistance are presented. It is shown that the current flowing through the plasma channel of such a low-current spark has the form of periodic pulses. It is experimentally demonstrated that, when a low-current spark transforms into a constricted glow discharge, current pulses disappear, the spatial structure of the cathode glow changes abruptly, and a brightly glowing positive plasma column forms in the gap.

Discharge mode transition and temporal-spatial evolution of an air-water plasma jet generated by pulsating DC power

NASA Astrophysics Data System (ADS)

Lei, J.; Geng, Y.; Liu, K.; Zhu, W.; Zheng, Z.; Hu, H.

2017-12-01

In this paper, pulsating direct current air-water plasma jet, which can increase the production of •OH and decrease the temperature, is studied. The results show that the discharge mode changes in one cycle from corona discharge with steep Trichel current pulse to glow-like discharge. It is unknown whether the different discharge modes and water ratio have an effect on the transient process of the excited O and •OH production and the mechanism of plasma propagation. So, a series of experiments are done in this paper. The results show that the changing rules of both the excited state O and the discharge current reach their two peak values synchronously. And its maximum appears at the time of the first peak current value in corona mode. However, the change of the excited state •OH is different. It increases to its maximum at the time of the second peak current value in glow-like mode. Besides, the intensified charge coupled device photographs show that the luminous intensity of the discharge zone at the first peak current value in corona mode is stronger than the second peak current value in glow-like mode. At the same time, the discharge area of the former is larger than the latter. Nevertheless, with the increase in water ratio, the discharge area change reversed. Additionally, the air plasma plume propagation depends on the gas flow. The initial propagation velocity decreases with the increase in water ratio.

On the physical processes ruling an atmospheric pressure air glow discharge operating in an intermediate current regime

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prevosto, L., E-mail: prevosto@waycom.com.ar; Mancinelli, B.; Chamorro, J. C.

2015-02-15

Low-frequency (100 Hz), intermediate-current (50 to 200 mA) glow discharges were experimentally investigated in atmospheric pressure air between blunt copper electrodes. Voltage–current characteristics and images of the discharge for different inter-electrode distances are reported. A cathode-fall voltage close to 360 V and a current density at the cathode surface of about 11 A/cm{sup 2}, both independent of the discharge current, were found. The visible emissive structure of the discharge resembles to that of a typical low-pressure glow, thus suggesting a glow-like electric field distribution in the discharge. A kinetic model for the discharge ionization processes is also presented with the aim of identifying themore » main physical processes ruling the discharge behavior. The numerical results indicate the presence of a non-equilibrium plasma with rather high gas temperature (above 4000 K) leading to the production of components such as NO, O, and N which are usually absent in low-current glows. Hence, the ionization by electron-impact is replaced by associative ionization, which is independent of the reduced electric field. This leads to a negative current-voltage characteristic curve, in spite of the glow-like features of the discharge. On the other hand, several estimations show that the discharge seems to be stabilized by heat conduction; being thermally stable due to its reduced size. All the quoted results indicate that although this discharge regime might be considered to be close to an arc, it is still a glow discharge as demonstrated by its overall properties, supported also by the presence of thermal non-equilibrium.« less

Electrical Versus Optical: Comparing Methods for Detecting Terahertz Radiation Using Neon Lamps

NASA Astrophysics Data System (ADS)

Slocombe, L. L.; Lewis, R. A.

2018-05-01

Terahertz radiation impinging on a lit neon tube causes additional ionization of the encapsulated gas. As a result, the electrical current flowing between the electrodes increases and the glow discharge in the tube brightens. These dual phenomena suggest two distinct modes of terahertz sensing. The electrical mode simply involves measuring the electrical current. The optical mode involves monitoring the brightness of the weakly ionized plasma glow discharge. Here, we directly compare the two detection modes under identical experimental conditions. We measure 0.1-THz radiation modulated at frequencies in the range 0.1-10 kHz, for lamp currents in the range 1-10 mA. We find that electrical detection provides a superior signal-to-noise ratio while optical detection has a faster response. Either method serves as the basis of a compact, robust, and inexpensive room-temperature detector of terahertz radiation.

The effect of frequency on atmospheric pressure glow discharge in a pin-to-plate gap sustained by a resonant power supply

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Yong Sheng; Ding, Wei Dong; Wang, Ya Nan

More and more researchers have been attracted to the research of atmospheric pressure glow discharge (APGD) because of its great prospect in numerous industrial applications. Nevertheless, almost all of the industrial applications are based on achievement of stable, large-volume, and uniform APGD. In a previous study, stable filamentary APGD was obtained by applying a resonant power supply between pin-to-plate electrodes which could limit the peak value of discharge current to supress the glow-to-arc transition through a series-wound resonance principle. The filamentary APGD is centimeter-level in the length but only several millimeters in diameter. Therefore, in order to obtain large-volume andmore » uniform APGD, it is significant to study how to diffuse filamentary APGD in radial direction. With the increasing resonant frequency of alternating current discharge, excited particles (mainly including energetic electrons and trapped ions left from the previous half-cycle discharge) in the electrodes gap increase, which benefits obtaining stable self-sustaining APGD. In this paper, mechanism and law of the influence of resonant frequency on the diffusion of filamentary APGD in ambient air were studied. By comparing the photos of discharge plasma and waveforms of the discharge voltage and current, it is found that the volume of the glow discharge plasma enlarges as the resonant frequency of the power supply increases. It is very significant and anticipating to study how to obtain stable, large-volume, and uniform APGD in ambient air by the resonant power supply.« less

Atmospheric sampling glow discharge ionization source

DOEpatents

McLuckey, S.A.; Glish, G.L.

1989-07-18

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. 3 figs.

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.

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.

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

NASA Astrophysics Data System (ADS)

Bacha, Tulu

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

On the shape of the glow discharge channel

NASA Astrophysics Data System (ADS)

Dmitriev, A. L.; Nikushchenko, E. M.

2017-05-01

Examples of the shapes of the glow discharge channel are presented. The discharge has been initiated in air at a pressure of 0.1 atm. The effective value and frequency of the discharge current are 30-70 mA and 50 Hz, respectively. It has been shown that, for these values of the current and pressure, thermal convection in a vacuum chamber and buoyancy (Archimedes force) are not major reasons for the specific parabolic shape of glow discharge.

Control of plasma properties in a short direct-current glow discharge with active boundaries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adams, S. F.; Demidov, V. I., E-mail: vladimir.demidov@mail.wvu.edu; West Virginia University, Morgantown, West Virginia 26506

2016-02-15

To demonstrate controlling electron/metastable density ratio and electron temperature by applying negative voltages to the active (conducting) discharge wall in a low-pressure plasma with nonlocal electron energy distribution function, modeling has been performed in a short (lacking the positive-column region) direct-current glow discharge with a cold cathode. The applied negative voltage can modify the trapping of the low-energy part of the energetic electrons that are emitted from the cathode sheath and that arise from the atomic and molecular processes in the plasma within the device volume. These electrons are responsible for heating the slow, thermal electrons, while production of slowmore » electrons (ions) and metastable atoms is mostly due to the energetic electrons with higher energies. Increasing electron temperature results in increasing decay rate of slow, thermal electrons (ions), while decay rate of metastable atoms and production rates of slow electrons (ions) and metastable atoms practically are unchanged. The result is in the variation of electron/metastable density ratio and electron temperature with the variation of the wall negative voltage.« less

Direct Detection Doppler Lidar Wind Measurements Obtained During the 2002 International H2O Project (IHOP)

NASA Technical Reports Server (NTRS)

Gentry, Bruce; Li, Steven; Chen, Huai-Lin; Comer, Joseph; Mathur, Savyasachee; Bobler, Jeremy

2005-01-01

The Goddard Lidar Observatory for Winds (GLOW) is a mobile Doppler lidar system that uses direct detection techniques for profiling winds in the troposphere and lower stratosphere. In May and June of 2002 GLOW was deployed to the Southern Great Plains of the US to participate in the International H2O Project (IHOP). GLOW was located at the Homestead profiling site in the Oklahoma panhandle about 15 km east of the SPOL radar. Several other Goddard lidars, the Scanning Raman Lidar (SRL) and HARLIE, as well as radars and passive instruments were permanently operated from the Homestead site during the IHOP campaign providing a unique cluster of observations. During the IHOP observation period (May 14, 2002 to June 25, 2002) over 240 hours of wind profile measurements were obtained with GLOW. In this paper we will describe the GLOW instrument as it was configured for the IHOP campaign and we will present examples of wind profiles obtained.

Wind Profiles Obtained with a Molecular Direct Detection Doppler Lidar During IHOP-2002

NASA Technical Reports Server (NTRS)

Gentry, Bruce M.; Chen, Huai-Lin; Li, Steven X.; Mathur, Savyasachee; Dobler, Jeremy; Hasselbrack, William; Comer, Joseph

2004-01-01

The Goddard Lidar Observatory for Winds (GLOW) is a mobile direct detection Doppler lidar system which uses the double edge technique to measure the Doppler shift of the molecular backscattered laser signal at a wavelength of 355 nm. In the spring of 2002 GLOW was deployed to the western Oklahoma profiling site (36 deg 33.500 min. N, 100 deg. 36.371 min. W) to participate in the International H2O Project (IHOP). During the IHOP campaign over 240 hours of wind profiles were obtained with the GLOW lidar in support of a variety of scientific investigations.

Characterization of direct-current atmospheric-pressure discharges useful for ambient desorption/ionization mass spectrometry.

PubMed

Shelley, Jacob T; Wiley, Joshua S; Chan, George C Y; Schilling, Gregory D; Ray, Steven J; Hieftje, Gary M

2009-05-01

Two relatively new ambient ionization sources, direct analysis in real time (DART) and the flowing atmospheric-pressure afterglow (FAPA), use direct current, atmospheric-pressure discharges to produce reagent ions for the direct ionization of a sample. Although at a first glance these two sources appear similar, a fundamental study reveals otherwise. Specifically, DART was found to operate with a corona-to-glow transition (C-G) discharge whereas the FAPA was found to operate with a glow-to-arc transition (G-A) discharge. The characteristics of both discharges were evaluated on the basis of four factors: reagent-ion production, response to a model analyte (ferrocene), infrared (IR) thermography of the gas used for desorption and ionization, and spatial emission characteristics. The G-A discharge produced a greater abundance and a wider variety of reagent ions than the C-G discharge. In addition, the discharges yielded different adducts and signal strengths for ferrocene. It was also found that the gas exiting the discharge chamber reached a maximum of 235 degrees C and 55 degrees C for the G-A and C-G discharges, respectively. Finally, spatially resolved emission maps of both discharges showed clear differences for N(2)(+) and O(I). These findings demonstrate that the discharges used by FAPA and DART are fundamentally different and should have different optimal applications for ambient desorption/ionization mass spectrometry (ADI-MS).

Common Gamma-ray Glows above Thunderclouds

NASA Astrophysics Data System (ADS)

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

2013-04-01

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

Reversal of radial glow distribution in helicon plasma induced by reversed magnetic field

NASA Astrophysics Data System (ADS)

Wang, Y.; Zhao, G.; Niu, C.; Liu, Z. W.; Ouyang, J. T.; Chen, Q.

2017-02-01

In this work, the reversal of radial glow distribution induced by reversed magnetic field is reported. Based on the Boswell antenna which is symmetric and insensitive to the magnetic field direction, it seems such a phenomenon in theory appears impossible. However, according to the diagnostic of the helicon waves by magnetic probe, it is found that the direction of magnetic field significantly affects the propagation characteristic of helicon waves, i.e., the interchange of the helicon waves at the upper and the lower half of tube was caused by reversing the direction of magnetic field. It is suggested that the variation of helicon wave against the direction of magnetic field causes the reversed radial glow distribution. The appearance of the traveling wave does not only improve the discharge strength, but also determines the transition of the discharge mode.

I'm sexy and I glow it: female ornamentation in a nocturnal capital breeder.

PubMed

Hopkins, Juhani; Baudry, Gautier; Candolin, Ulrika; Kaitala, Arja

2015-10-01

In many species, males rely on sexual ornaments to attract females. Females, by contrast, rarely produce ornaments. The glow-worm (Lampyris noctiluca) is an exception where wingless females glow to attract males that fly in search of females. However, little is known about the factors that promote the evolution of female ornaments in a sexual selection context. Here, we investigated if the female ornament of the glow-worm is a signal of fecundity used in male mate choice. In support of this, we found brightness to correlate with female fecundity, and males to prefer brighter dummy females. Thus, the glow emitted by females is a reliable sexual signal of female fecundity. It is likely that male preference for the fecundity-indicating ornament has evolved because of large variation among females in fecundity, and because nocturnal males cannot directly assess female size and fecundity. These results indicate that female ornamentation may evolve in capital breeders (i.e. those in which stored resources are invested in reproduction) when females vary significantly in fecundity and this variation cannot be assessed directly by males. © 2015 The Author(s).

Generation of multiple toroidal dust vortices by a non-monotonic density gradient in a direct current glow discharge plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaur, Manjit, E-mail: manjit@ipr.res.in; Bose, Sayak; Chattopadhyay, P. K.

2015-09-15

Observation of two well-separated dust vortices in an unmagnetized parallel plate DC glow discharge plasma is reported in this paper. A non-monotonic radial density profile, achieved by an especially designed cathode structure using a concentric metallic disk and ring of different radii, is observed to produce double dust tori between cathode and anode. PIV analysis of the still images of the double tori shows oppositely rotating dust structures between the central disk and the ring. Langmuir probe measurements of background plasma shows a non-uniform plasma density profile between the disk and the ring. Location and sense of rotation of themore » dust vortices coincides with the location and direction of the radial gradient in the ion drag force caused by the radial density gradient. The experimentally observed dust vorticity matches well with the calculated one using hydrodynamic formulations with shear in ion drag dominating over the dust charge gradient. These results corroborate that a radial gradient in the ion drag force directed towards cathode is the principal cause of dust rotation.« less

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, Weiman; Tang, Jie; Wang, Yishan

2013-07-15

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

Glow discharge plasma deposition of thin films

DOEpatents

Weakliem, Herbert A.; Vossen, Jr., John L.

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.

Localised and delocalised optically induced conversion of composite glow peak 5 in LiF:Mg,Ti (TLD-100) to glow peak 4 as a function of postirradiation annealing temperature.

PubMed

Horowitz, Y S; Einav, Y; Biderman, S; Oster, L

2002-01-01

The composite structure of glow peak 5 in LiF:Mg,Ti (TLD-100) has been investigated using optical bleaching by 310 nm (4 eV) light. The glow peak conversion efficiency of peak 5a (Tm = 187 degrees C) to peak 4 traps is very high at a value of 3+/-0.5 (1 SD) whereas the glow peak conversion efficiency of peak 5 (Tm = 205 degrees C) to peak 4 traps is 0.0026+/-0.0012 (1 SD). The high conversion efficiency of peak 5a to peak 4 arises from direct optical ionisation of the electron in the electron-hole pair. leaving behind a singly-trapped hole (peak 4), a direct mechanism, relatively free of competitive mechanisms. Optical ionisation of the 'singly-trapped' electron (peak 5), however, can lead to peak 4 only via multi-stage mechanisms involving charge carrier transport in the valence and conduction bands, a mechanism subject to competitive processes. The conduction/valence band competitive processes lead to the factor of one thousand decrease in the conversion efficiency of peak 5 compared to peak 5a.

Nonlinear time-series analysis of current signal in cathodic contact glow discharge electrolysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Allagui, Anis, E-mail: aallagui@sharjah.ac.ae; Abdelkareem, Mohammad Ali; Rojas, Andrea Espinel

In the standard two-electrode configuration employed in electrolytic process, when the control dc voltage is brought to a critical value, the system undergoes a transition from conventional electrolysis to contact glow discharge electrolysis (CGDE), which has also been referred to as liquid-submerged micro-plasma, glow discharge plasma electrolysis, electrode effect, electrolytic plasma, etc. The light-emitting process is associated with the development of an irregular and erratic current time-series which has been arbitrarily labelled as “random,” and thus dissuaded further research in this direction. Here, we examine the current time-series signals measured in cathodic CGDE configuration in a concentrated KOH solution atmore » different dc bias voltages greater than the critical voltage. We show that the signals are, in fact, not random according to the NIST SP. 800-22 test suite definition. We also demonstrate that post-processing low-pass filtered sequences requires less time than the native as-measured sequences, suggesting a superposition of low frequency chaotic fluctuations and high frequency behaviors (which may be produced by more than one possible source of entropy). Using an array of nonlinear time-series analyses for dynamical systems, i.e., the computation of largest Lyapunov exponents and correlation dimensions, and re-construction of phase portraits, we found that low-pass filtered datasets undergo a transition from quasi-periodic to chaotic to quasi-hyper-chaotic behavior, and back again to chaos when the voltage controlling-parameter is increased. The high frequency part of the signals is discussed in terms of highly nonlinear turbulent motion developed around the working electrode.« less

Torus Breakdown and Homoclinic Chaos in a Glow Discharge Tube

NASA Astrophysics Data System (ADS)

Ginoux, Jean-Marc; Meucci, Riccardo; Euzzor, Stefano

2017-12-01

Starting from historical researches, we used, like Van der Pol and Le Corbeiller, a cubic function for modeling the current-voltage characteristic of a direct current low-pressure plasma discharge tube, i.e. a neon tube. This led us to propose a new four-dimensional autonomous dynamical system allowing to describe the experimentally observed phenomenon. Then, mathematical analysis and detailed numerical investigations of such a fourth-order torus circuit enabled to highlight bifurcation routes from torus breakdown to homoclinic chaos following the Newhouse-Ruelle-Takens scenario.

Comparison between Trichel pulse in negative corona and self-pulsing in other configurations

NASA Astrophysics Data System (ADS)

Xia, Qing; Zhang, Yu; He, Feng; Qin, Yu; Jiang, Zhaorui; Ouyang, Jiting

2018-02-01

We present here a comparison study on self-pulsing phenomena in negative corona, hollow cathode discharges (HCD) and parallel-plate discharge in air. The voltage-current (V-I) curve, the waveforms of self-pulsed currents, and the time-resolved images of the pulsed discharge are measured under various operating conditions. It is experimentally evidenced that the Trichel pulse in a negative corona and the self-pulsing in HCD and/or parallel-plate discharge have similar features as well as spatial-temporal developing process. It is suggested that they should have a similar mechanism that the pulsing reflects the mode transition of discharge between the low-current Townsend and the high-current normal glow. The pulse rising corresponds to the breakdown and formation of temporal glow discharge in a background of low-current Townsend discharge, while the decay edge relates to the transition back to Townsend discharge. The pulse interval is the re-building process of the space charge layer of high density to ensure the glow breakdown.

Dual-frequency glow discharges in atmospheric helium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Xiaojiang; Guo, Ying; Magnetic Confinement Fusion Research Center, Ministry of Education of the People's Republic of China, Shanghai 201620

2015-10-15

In this paper, the dual-frequency (DF) glow discharges in atmospheric helium were experimented by electrical and optical measurements in terms of current voltage characteristics and optical emission intensity. It is shown that the waveforms of applied voltages or discharge currents are the results of low frequency (LF) waveforms added to high frequency (HF) waveforms. The HF mainly influences discharge currents, and the LF mainly influences applied voltages. The gas temperatures of DF discharges are mainly affected by HF power rather than LF power.

Comment on the paper "Thermoluminescence glow-curve deconvolution functions for mixed order of kinetics and continuous trap distribution by G. Kitis, J.M. Gomez-Ros, Nuclear Instruments and Methods in Physics Research A 440, 2000, pp 224-231"

NASA Astrophysics Data System (ADS)

Kazakis, Nikolaos A.

2018-01-01

The present comment concerns the correct presentation of an algorithm proposed in the above paper for the glow-curve deconvolution in the case of continuous distribution of trapping states. Since most researchers would use directly the proposed algorithm as published, they should be notified of its correct formulation during the fitting of TL glow curves of materials with continuous trap distribution using this Equation.

Low-temperature plasma simulations with the LSP PIC code

NASA Astrophysics Data System (ADS)

Carlsson, Johan; Khrabrov, Alex; Kaganovich, Igor; Keating, David; Selezneva, Svetlana; Sommerer, Timothy

2014-10-01

The LSP (Large-Scale Plasma) PIC-MCC code has been used to simulate several low-temperature plasma configurations, including a gas switch for high-power AC/DC conversion, a glow discharge and a Hall thruster. Simulation results will be presented with an emphasis on code comparison and validation against experiment. High-voltage, direct-current (HVDC) power transmission is becoming more common as it can reduce construction costs and power losses. Solid-state power-electronics devices are presently used, but it has been proposed that gas switches could become a compact, less costly, alternative. A gas-switch conversion device would be based on a glow discharge, with a magnetically insulated cold cathode. Its operation is similar to that of a sputtering magnetron, but with much higher pressure (0.1 to 0.3 Torr) in order to achieve high current density. We have performed 1D (axial) and 2D (axial/radial) simulations of such a gas switch using LSP. The 1D results were compared with results from the EDIPIC code. To test and compare the collision models used by the LSP and EDIPIC codes in more detail, a validation exercise was performed for the cathode fall of a glow discharge. We will also present some 2D (radial/azimuthal) LSP simulations of a Hall thruster. The information, data, or work presented herein was funded in part by the Advanced Research Projects Agency-Energy (ARPA-E), U.S. Department of Energy, under Award Number DE-AR0000298.

Self-consistent modeling of self-organized patterns of spots on anodes of DC glow discharges

NASA Astrophysics Data System (ADS)

Bieniek, M. S.; Almeida, P. G. C.; Benilov, M. S.

2018-05-01

Self-organized patterns of spots on a flat metallic anode in a cylindrical glow discharge tube are simulated. A standard model of glow discharges is used, comprising conservation and transport equations for a single species of ion and electrons, written with the use of the drift-diffusion and local-field approximations, and the Poisson equation. Only processes in the near-anode region are considered and the computation domain is the region between the anode and the discharge column. Multiple solutions, existing in the same range of discharge current and describing modes with and without anode spots, are computed for the first time. A reversal of the local anode current density in the spots was found, i.e. mini-cathodes are formed inside the spots or, as one could say, anode spots operate as a unipolar glow discharge. The solutions do not fit into the conventional pattern of self-organization in bistable nonlinear dissipative systems; In particular, the modes are not joined by bifurcations.

Removal of a hydrogenated amorphous carbon film from the tip of a micropipette electrode using direct current corona discharge.

PubMed

Kakuta, Naoto; Okuyama, Naoki; Yamada, Yukio

2010-02-01

Micropipette electrodes are fabricated by coating glass micropipettes first with metal and then with hydrogenated amorphous carbon (a-C:H) as an electrical insulator. Furthermore, at the tip of the micropipette electrode, the deposited a-C:H film needs to be removed to expose the metal-coated surface and hollow for the purposes of electrical measurement and injection. This paper describes a convenient and reliable method for removing the a-C:H film using direct current corona discharge in atmospheric air. The initial film removal occurred at an applied voltage of 1.5-2.0 kV, accompanied by an abrupt increase in the discharge current. The discharge current then became stable at a microampere level in the glow corona mode, and the removed area gradually extended.

Investigation of atmospheric pressure glow microdischarge between flat cathode and needle anode in helium and argon

NASA Astrophysics Data System (ADS)

Astafiev, Alexander; Belyaev, Vladimir; Zamchii, Roman; Kudryavtsev, Anatoly; Stepanova, Olga; Chen, Zhaoquan

2016-09-01

DC atmospheric-pressure glow microdischarge was generated between a flat cathode and needle anode with a diameter of 100 μm in a special chamber with helium or argon. Dependences of discharge parameters on an interelectrode gap was investigated with an original experimental setup based on a movable arm on the hinge joint which allowed changing the gap with a step of 5 μm. The gap was varied from 5 to 700 μm. Discharge current was 1-21 mA. Such discharge cell has a very low interelectrode capacitance and provides increasing the stability of the discharge against arc formation (transition to RC oscillations mode) at low currents of 1 mA. A weak dependence of discharge voltage across the gap was revealed in helium at 100-250 μm between the electrodes (normal discharge). In contrast to this, glow microdischarge in argon has a descending current-voltage characteristic and unstable nature. The discharge voltage depending on the gap changes significantly slower than in helium. According to our estimations, the strength of electrical field of positive glow in argon is 5 times lower than in helium. Saint Petersburg State University (Grant No. 0.37.218.2016).

[Studies on the general properties of a novel microwave plasma enhanced glow discharge source].

PubMed

Li, Y; Du, Z; Duan, Y; Zhang, H; Jin, Q; Liu, H

1998-04-01

This paper introduced a novel microwave plasma enhanced glow descharge source, the structure design and operation were decribed, and the mutual effects of the main characters, such as pressure, current, voltage, microwave power and sputtering rates were also investigated in details.

Effect of anode oxide films on glow discharge spatial structure

NASA Astrophysics Data System (ADS)

Gulamov, E. N.; Islamov, R. S.; Zabelin, Alexandre M.

1994-04-01

A self-consistent calculation of voltage fall on the anode film as a function of its resistance has been performed in the presence of anode current spots under elevated-pressure glow discharge in nitrogen and N2:He equals 1:1 mixture. It has been shown that resistance of anode oxide films in industrial lasers with continuous copper anode can reach the values when total suppression of anode current structures takes place.

Long duration gamma-ray emission from thunderclouds

NASA Astrophysics Data System (ADS)

Kelley, Nicole A.

Gamma-ray glows are long duration emission coming from thunderclouds. They are one example of high-energy atmospheric physics, a relatively new field studying high-energy phenomena from thunderstorms and lightning. Glows arise from sustained relativistic runaway electron avalanches (RREA). Gamma-ray instruments on the ground, balloons and airplanes have detected glows. The Airborne Detector for Energetic Lightning Emissions (ADELE) is an array of gamma-ray detectors, built at the University of California, Santa Cruz. ADELE detected 12 gamma-ray glows during its summer 2009 campaign. ADELE was designed to study another type of high-energy atmospheric physics, terrestrial gamma-ray flashes (TGFs). TGFs are incredibly bright, sub-millisecond bursts of gamma-rays coming from thunderstorms. ADELE was installed on NCAR's Gulfstream V for the summer of 2009. While many glows were detected, only one TGF was observed. In this thesis I present a detailed explanation of the 2009 version of ADELE along with the results of the 2009 campaign. ADELE was modified to become a smaller, autonomous instrument to fly on the NASA drone, a Global Hawk. This was a piggyback to NASA's Hurricane and Severe Storm Sentinel mission. These flights took place during the summer of 2013. The following summer, ADELE flew on an Orion P3 as a piggyback of NOAA's Hurricane Hunters. This newer, modified instrument is discussed in detail in this thesis. The 12 gamma-ray glows from the 2009 campaign are presented, with information about nearby lightning activity. I show that lightning activity is suppressed after a glow. This could be from the glow causing the cloud to discharge and therefore reduce the lightning activity. It is also possible that glows can only occur once lightning activity has diminished. Lightning is also used to find a distance to the glow. Using this distance, it is found that the brightness of glow cannot be explained as a function of distance while the duration of the glow is related to the distance. The glow measured on August 21, 2009 was 20 times brighter than any other glow. This glow was modeled most extensively and it was found that ADELE was in the end of a downward facing avalanche, implying that is was lying between the upper positive and negative screening layer of the thunderstorm. The brightness of this glow also showed that the avalanche was approaching the levels necessary for relativistic feedback. I also show that this glow provides a significant discharge current and for a short while is discharging the cloud as much as nearby lightning.

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.

Infrared emission associated with chemical reactions on Shuttle and SIRTF surfaces

NASA Technical Reports Server (NTRS)

Hollenbach, D. J.; Tielens, Alexander G. G. M.

1984-01-01

The infrared intensities which would be observed by the Shuttle Infrared Telescope Facility (SIRTF), and which are produced by surface chemistry following atmospheric impact on SIRTF and the shuttle are estimated. Three possible sources of reactants are analyzed: (1) direct atmospheric and scattered contaminant fluxes onto the shuttle's surface; (2) direct atmospheric and scattered contaminant fluxes onto the SIRTF sunshade; and (3) scattered fluxes onto the cold SIRTF mirror. The chemical reactions are primarily initiated by the dominent flux of reactive atomic oxygen on the surfaces. Using observations of the optical glow to constrain theoretical parameters, it is estimated for source (1) that the infrared glow on the SIRTF mirror will be comparable to the zodiacal background between 1 and 10 micron wavelengths. It is speculated that oxygen reacts with the atoms and the radicals bound in the organic molecules that reside on the shuttle and the Explorer surfaces. It is concluded that for source (2) that with suitable construction, a warm sunshade will produce insignificant infrared glow. It is noted that the atomic oxygen flux on the cold SIRTF mirror (3) is insufficient to produce significant infrared glow. Infrared absorption by the ice buildup on the mirror is also small.

Note: Measurement of the cathode layer thickness in glow discharges with a Langmuir probe

NASA Astrophysics Data System (ADS)

Wang, Hao; Hou, Xinyu; Zou, Xiaobing; Luo, Haiyun; Wang, Xinxin

2018-06-01

A method using a Langmuir probe to determine the thickness of the cathode layer for a glow discharge is developed. The method is based on the phenomenon that the curve of the voltage-current characteristics changes in shape as the Langmuir probe moves from the positive column into the cathode layer. The method was used to measure the thicknesses of the cathode layer in the normal glow discharges of argon and air with the cathodes made from stainless steel and aluminum. The results are in good agreement with those given in a book of gas discharge.

Pulsed glow discharge enables direct mass spectrometric measurement of fluorine in crystal materials - Fluorine quantification and depth profiling in fluorine doped potassium titanyl phosphate

NASA Astrophysics Data System (ADS)

Bodnar, Victoria; Ganeev, Alexander; Gubal, Anna; Solovyev, Nikolay; Glumov, Oleg; Yakobson, Viktor; Murin, Igor

2018-07-01

A pulsed direct current glow discharge time-of-flight mass spectrometry (GD TOF MS) method for the quantification of fluorine in insoluble crystal materials with fluorine doped potassium titanyl phosphate (KTP) KTiOPO4:KF as an example has been proposed. The following parameters were optimized: repelling pulse delay, discharge duration, discharge voltage, and pressure in the discharge cell. Effective ionization of fluorine in the space between sampler and skimmer under short repelling pulse delay, related to the high-energy electron impact at the discharge front, has been demonstrated. A combination of instrumental and mathematical correction approaches was used to cope for the interferences of 38Ar2+ and 1H316O + on 19F+. To maintain surface conductivity in the dielectric KTP crystals and insure its effective sputtering in combined hollow cathode cell, silver suspension applied by the dip-coating method was employed. Fluorine quantification was performed using relative sensitivity factors. The analysis of a reference material and scanning electron microscope-energy dispersive X-ray spectroscopy was used for validation. Fluorine limit of detection by pulsed direct current GD TOF MS was 0.01 mass%. Real sample analysis showed that fluorine seems to be inhomogeneously distributed in the crystals. That is why depth profiling of F, K, O, and P was performed to evaluate the crystals' non-stoichiometry. The approaches designed allow for fluorine quantification in insoluble dielectric materials with minimal sample preparation and destructivity as well as performing depth profiling to assess crystal non-stoichiometry.

Ultraviolet Rayleigh Scatter Imaging for Spatial Temperature Profiles in Atmospheric Microdischarges

DTIC Science & Technology

2014-09-01

regime and not in a neighboring regime such as an abnormal glow or a corona discharge . As discussed in section 3.1, unlike abnormal discharges or... coronas , normal glows have a voltage drop that is independent of discharge current for several orders of magnitude, which would manifest itself...5 3.2 Discharge Power and Gas Temperature

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

PubMed

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

2011-03-01

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

Prebreakdown phenomena and formation process of the glow discharge in low-pressure Ar gas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hosokawa, Tatsuzo; Goto, Kazuhiro; Ohuchi, Mikio

2001-06-01

The prebreakdown phenomena and the formation process of the glow discharge in a low-pressure Ar gas were investigated under a uniform field gap. Prebreakdown phenomena were observed for 0.5Torrcm{le}pd{le}2Torrcm (where p is pressure, d the gap distance) in Ar gas under conditions of a slowly increasing voltage. It was observed that the prebreakdown phenomena formed pulse discharges up to the transition to the glow discharge. The amplitudes of the photon and current pulses due to the pulse discharge increased with time, and then decreased as soon as the transition to a steady glow discharge occurred. When the overvoltage or externalmore » series resistance was increased, the pulse amplitudes increased with the applied voltage and decreased with the resistance. The characteristics of the prebreakdown phenomena were changed by the shape of the electrodes. The formation mechanism of the glow discharge can be qualitatively explained by that of the streamer in a high-pressure discharge. The transient glow discharge was observed, and its duration increased with an increase in resistance. The instability of the glow discharge was controlled by three factors, namely, Kaufmann{close_quote}s criterion, the Child{endash}Langmuir law, and the density balance between the production and removal rates of electrons. {copyright} 2001 American Institute of Physics.« less

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akhmadeev, Yu. H.; Denisov, V. V., E-mail: volodyadenisov@yandex.ru; Koval, N. N.

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

Experimental investigation of high temperature high voltage thermionic diode for the space power nuclear reactor

NASA Astrophysics Data System (ADS)

Onufriyev, Valery. V.

2001-02-01

It is well known that the rise of arc from the dense glow discharge is connected with the thermion and secondary processes on the cathode surface (Granovsky, 1971; Leob, 1953; Engel, 1935). First model of breakdown of the cathode layer is connected with the increase of the cathode temperature in consequence of the ion bombardment that leads to the grows its thermo-emissive current. Other model shows the main role of the secondary effects on the cathode surface-the increase of the secondary ion emission coefficient-γi with the grows of glow discharge voltage. But the author of this investigation work of breakdown in Cs vapor (a transmission the glow discharge into self-maintaining arc discharge) discovered the next peculiarity: the value of breakdown voltage is constant when the values of vapor temperature (its pressure pcs) and cathode temperature Tk is constant too (Ub=constant with Tk=constant and pcs=constant) and it is not a statistical value (Onufryev, Grishin, 1996) (that was observed in gas glow discharges other authors (Granovsky, 1971; Leob, 1953; Engel, 1935)). The investigations of thermion high voltage high temperature diode (its breakdown characteristics in closed state and voltage-current characteristics in disclosed state) showed that the value of the breakdown voltage is depended on the vapor pressure in inter-electrode gap (IEG)-pcs and cathode temperature-Tk and is independent on IEG length-Δieg. On this base it was settled that the main role in transition of glow discharge to self-maintaining arc discharge plays an ion cathode layer but more exactly-the region of excited atoms-``Aston glow.'' .

Glow discharge spectrometry for the characterization of nuclear and radioactively contaminated environmental samples

NASA Astrophysics Data System (ADS)

Betti, Maria; Aldave de las Heras, Laura

2004-09-01

Glow discharge (GD) spectrometry as applied to characterize nuclear samples as well as for the determination of radionuclides in environmental samples is reviewed. The use of instrumentation for direct current (d.c.) glow discharge mass spectrometry (GDMS) and radio frequency glow discharge optical emission spectrometry (rf GDOES), installed inside a glove-box for the handling of radioactive samples as well as the two installations and their analytical possibilities, is described in detail. The applications of GD techniques for the characterization of samples of nuclear concern both with respect to their major and trace elements, as well as to the matrix isotopic composition are presented. Procedures for quantitative determination of major, minor, and trace elements in conductive samples are reported. As for non-conductive samples three different approaches for their measurement can be followed. Namely, the use of rf sources, the mixing of the sample with a binder conducting host matrix, and the use of a secondary cathode. In the case of oxide-based samples, the employment of a tantalum secondary cathode, acting as an oxygen getter, reduces the availability of oxygen to form polyatomic species and to produce quenching. Considerations on the use of the relative sensitivity factors (RSFs) in different matrices are reported. The analytical capabilities of GDMS are compared with ICP-MS in terms of accuracy, precision, and detection limit for the determination of trace elements in uranium oxide specimens. As for the determination of isotopic composition, GDMS was found to be competitive with thermal ionisation mass spectrometry (TIMS) as well as for bulk determinations of major elements with titration methods. Applications of GDMS to the determination of radioisotopes in environmental samples, as well for depth profiling of trace elements in oxide layers, are discussed.

Mass dependency of turbulent parameters in stationary glow discharge plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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

Characteristics and time evolution of a hollow cathode produced glow discharge plasma in air

NASA Astrophysics Data System (ADS)

Gregor, Joseph Atilla

Current radar systems use mechanical directors and phased array technology for beam steering. Use of a sheet plasma as a microwave reflector promises several advantages over these methods. Operation is inherently broad-band, since all frequencies below the plasma frequency are reflected. The orientation and shape of the reflector may be changed directly through electronic control without resort to moving parts or expensive RF switches. The relatively fast plasma formation and extinction times ([/approx]10/ /mus) allow for rapid redirection of the microwave beam. An experimental system, dubbed the Agile Mirror, has been constructed using a cylindrical LexanTM vacuum chamber suspended within a water cooled Helmholtz coil pair capable of producing a uniform 500 Gauss field. Using this system we have created plasmas capable of reflecting 10 GHz microwaves with characteristics comparable to that of a plane metallic reflector. Most previous glow discharge work has concentrated either on the DC characteristics, or on the very early evolution (<1-2 μs), of the discharge. To create a practical agile mirror direction, we must be able to produce a stable, flat, homogeneous plasma sheet with predictable characteristics timescales from 5 μs to 1 ms-a regime where little pertinent quantitative data exists. This work concentrates on diagnosing the time resolved behavior of the agile mirror plasma during the mid-time, from t = 5-300 μs, in a regime which accentuates observed changes in the discharge circuit characteristics. Measurements on an air discharge produced using VD/approx2.2 kV, p ≈ 208 mTorr, and B ≈ 250 G reveal an ne=1011/ cm-3,/ Te=1[-]3 eV plasma with distinct negative glow, Faraday dark space, and positive column regions. Analysis of time resolved potential, temperature, and spectroscopic data reveal that this discharge transitions-on time scales of [/approx]100/ /mus-into a pure negative glow discharge. The characteristics and evolution of the discharge are highly reproducible. A computer model of the discharge reveals that heating of the background gas is responsible for the transition. Implications for operation of the agile mirror discharge as a plasma mirror are discussed.

Electron concentration distribution in a glow discharge in air flow

NASA Astrophysics Data System (ADS)

Mukhamedzianov, R. B.; Gaisin, F. M.; Sabitov, R. A.

1989-04-01

Electron concentration distributions in a glow discharge in longitudinal and vortex air flows are determined from the attenuation of the electromagnetic wave passing through the plasma using microwave probes. An analysis of the distribution curves obtained indicates that electron concentration decreases in the direction of the anode. This can be explained by charge diffusion toward the chamber walls and electron recombination and sticking within the discharge.

Application of Direct Current Atmospheric Pressure Glow Microdischarge Generated in Contact with a Flowing Liquid Solution for Synthesis of Au-Ag Core-Shell Nanoparticles.

PubMed

Dzimitrowicz, Anna; Jamroz, Piotr; Nyk, Marcin; Pohl, Pawel

2016-04-06

A direct current atmospheric pressure glow microdischarge (dc-μAPGD) generated between an Ar nozzle microjet and a flowing liquid was applied to produce Au-Ag core-shell nanoparticles (Au@AgCSNPs) in a continuous flow system. Firstly, operating dc-μAPGD with the flowing solution of the Au(III) ions as the cathode, the Au nanoparticles (AuNPs) core was produced. Next, to produce the core-shell nanostructures, the collected AuNPs solution was immediately mixed with an AgNO₃ solution and passed through the system with the reversed polarity to fabricate the Ag nanoshell on the AuNPs core. The formation of Au@AgCSNPs was confirmed using ultraviolet-visible (UV-Vis) absorbance spectrophotometry, transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDS). Three localized surface plasmon resonance absorption bands with wavelengths centered at 372, 546, and 675 nm were observed in the UV-Vis spectrum of Au@AgCSNPs, confirming the reduction of both the Au(III) and Ag(I) ions. The right configuration of metals in Au@AgCSNPs was evidenced by TEM. The Au core diameter was 10.2 ± 2.0 nm, while the thickness of the Ag nanoshell was 5.8 ± 1.8 nm. The elemental composition of the bimetallic nanoparticles was also confirmed by EDS. It is possible to obtain 90 mL of a solution containing Au@AgCSNPs per hour using the applied microdischarge system.

Simulation of nonstationary phenomena in atmospheric-pressure glow discharge

NASA Astrophysics Data System (ADS)

Korolev, Yu. D.; Frants, O. B.; Nekhoroshev, V. O.; Suslov, A. I.; Kas'yanov, V. S.; Shemyakin, I. A.; Bolotov, A. V.

2016-06-01

Nonstationary processes in atmospheric-pressure glow discharge manifest themselves in spontaneous transitions from the normal glow discharge into a spark. In the experiments, both so-called completed transitions in which a highly conductive constricted channel arises and incomplete transitions accompanied by the formation of a diffuse channel are observed. A model of the positive column of a discharge in air is elaborated that allows one to interpret specific features of the discharge both in the stationary stage and during its transition into a spark and makes it possible to calculate the characteristic oscillatory current waveforms for completed transitions into a spark and aperiodic ones for incomplete transitions. The calculated parameters of the positive column in the glow discharge mode agree well with experiment. Data on the densities of the most abundant species generated in the discharge (such as atomic oxygen, metastable nitrogen molecules, ozone, nitrogen oxides, and negative oxygen ions) are presented.

Simulation of nonstationary phenomena in atmospheric-pressure glow discharge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Korolev, Yu. D., E-mail: korolev@lnp.hcei.tsc.ru; Frants, O. B.; Nekhoroshev, V. O.

2016-06-15

Nonstationary processes in atmospheric-pressure glow discharge manifest themselves in spontaneous transitions from the normal glow discharge into a spark. In the experiments, both so-called completed transitions in which a highly conductive constricted channel arises and incomplete transitions accompanied by the formation of a diffuse channel are observed. A model of the positive column of a discharge in air is elaborated that allows one to interpret specific features of the discharge both in the stationary stage and during its transition into a spark and makes it possible to calculate the characteristic oscillatory current waveforms for completed transitions into a spark andmore » aperiodic ones for incomplete transitions. The calculated parameters of the positive column in the glow discharge mode agree well with experiment. Data on the densities of the most abundant species generated in the discharge (such as atomic oxygen, metastable nitrogen molecules, ozone, nitrogen oxides, and negative oxygen ions) are presented.« less

Controlled growth of aligned carbon nanotube using pulsed glow barrier discharge

NASA Astrophysics Data System (ADS)

Nozaki, Tomohiro; Kimura, Yoshihito; Okazaki, Ken

2002-10-01

We first achieved a catalytic growth of aligned carbon nanotube (CNT) using atmospheric pressure pulsed glow barrier discharge combined with DC bias (1000 V). Aligned CNT can grow with the directional electric field, and this is a big challenge in barrier discharges since dielectric barrier does not allow DC bias and forces to use AC voltage to maintain stable plasma conditions. To overcome this, we developed a power source generating Gaussian-shape pulses at 20 kpps with 4% duty, and DC bias was applied to the GND electrode where Ni-, Fe-coated substrate existed. With positive pulse, i.e. substrate was the cathode, random growth of CNT was observed at about 10^9 cm-2. Growth rate significantly reduced when applied negative pulse; Negative glow formation near substrate is essential for sufficient supply of radical species to the catalyst. If -DC was biased, aligned CNT with 20 nm was synthesized because negative bias enhanced negative glow formation. Interestingly, 2 to 3 CNTs stuck each other with +DC bias, resulting in 50-70 nm and non-aligned CNT. Atmospheric pressure glow barrier discharges can be highly controlled and be a potential alternative to vacuum plasmas for CVD, micro-scale, nano-scale fabrication.

Foundations of DC plasma sources

NASA Astrophysics Data System (ADS)

Tomas Gudmundsson, Jon; Hecimovic, Ante

2017-12-01

A typical dc discharge is configured with the negative cathode at one end and a positive anode at the other end, separated by a gas filled gap, placed inside a long glass cylinder. A few hundred volts between the cathode and anode is required to maintain the discharge. The type of discharge that is formed between the two electrodes depends upon the pressure of the working gas, the nature of the working gas, the applied voltage and the geometry of the discharge. We discuss the current-voltage characteristics of the discharge as well as the distinct structure that develops in the glow discharge region. The dc glow discharge appears in the discharge current range from μA to mA at 0.5-300 Pa pressure. We discuss the various phenomena observed in the dc glow discharge, including the cathode region, the positive column, and striations. The dc glow discharge is maintained by the emission of secondary electrons from the cathode target due to the bombardment of ions. For decades, the dc glow discharge has been used as a sputter source. Then it is often operated as an obstructed abnormal glow discharge and the required applied voltage is in the range 2-5 kV. Typically, the cathode target (the material to be deposited) is connected to a negative voltage supply (dc or rf) and the substrate holder faces the target. The relatively high operating pressure, in the range from 2 to 4 Pa, high applied voltages, and the necessity to have a conductive target limit the application of dc glow discharge as a sputter source. In order to lower the discharge voltage and expand the operation pressure range, the lifetime of the electrons in target vicinity is increased through applying magnetic field, by adding permanent magnets behind the cathode target. This arrangement is coined the magnetron sputtering discharge. The various configurations of the magnetron sputtering discharge and its applications are described. Furthermore, the use of dc discharges for chemical analysis, the Penning discharge and the hollow cathode discharges and some of its applications are briefly discussed.

Evolution of Multiple Double Layer in Glow discharge and its inherent Properties

NASA Astrophysics Data System (ADS)

Alex, Prince; A, Saravanan; Sinha, Suraj

2016-10-01

Formation and evolution of multiple anodic double layers (MADLs) were experimentally studied in glow discharge plasma. The boundary condition for the existence of MADL was identified in terms of threshold bias and ambient working pressure. The MADL formation is accompanied by an explosive growth in anode current and consequent current-voltage characteristics follows a hysteresis loop. The analysis yield that stable MADLs is only observed when the control voltage V2 is between a certain critical values (Vq > νte MADL completely transforms to an intense high current carrying unstable anode glow. The floating potential analysis carried out using three axially positioned electrostatic probes shows a bipolar signature of DL with as the control parameter is varied. The floating potential analysis also shows that hysteresis arises due to the difference in magnitude of electric field required to align the space charges in the DL sheet at the control voltage changes forward and backward. The effect of pressure on MADL indicates that the MADL structure advances towards anode surface as the pressure is increases. The power dumped (W) in the MADL is estimated to decrease with increase in pressure while the same increase in the anode glow.

Temporally, spatially, and spectrally resolved barrier discharge produced in trapped helium gas at atmospheric pressure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chiper, Alina Silvia; Popa, Gheorghe

2013-06-07

Experimental study was made on induced effects by trapped helium gas in the pulsed positive dielectric barrier discharge (DBD) operating in symmetrical electrode configuration at atmospheric pressure. Using fast photography technique and electrical measurements, the differences in the discharge regimes between the stationary and the flowing helium are investigated. It was shown experimentally that the trapped gas atmosphere (TGA) has notable impact on the barrier discharge regime compared with the influence of the flowing gas atmosphere. According to our experimental results, the DBD discharge produced in trapped helium gas can be categorized as a multi-glow (pseudo-glow) discharge, each discharge workingmore » in the sub-normal glow regime. This conclusion is made by considering the duration of current pulse (few {mu}s), their maximum values (tens of mA), the presence of negative slope on the voltage-current characteristic, and the spatio-temporal evolution of the most representative excited species in the discharge gap. The paper focuses on the space-time distribution of the active species with a view to better understand the pseudo-glow discharge mechanism. The physical basis for these effects was suggested. A transition to filamentary discharge is suppressed in TGA mode due to the formation of supplementary source of seed electrons by surface processes (by desorption of electrons due to vibrationally excited nitrogen molecules, originated from barriers surfaces) rather than volume processes (by enhanced Penning ionisation). Finally, we show that the pseudo-glow discharge can be generated by working gas trapping only; maintaining unchanged all the electrical and constructive parameters.« less

Self-pulsing in a low-current hollow cathode discharge: From Townsend to glow discharge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qin, Yu; School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081; Xie, Kan, E-mail: xiekan@bit.edu.cn

We investigate the self-pulsing phenomenon of a low current cavity discharge in a cylindrical hollow cathode in pure argon. The waveforms of pulsed current and voltage are measured, and the time-averaged and time-resolved images of hollow cathode discharge are recorded by using high-speed intensified charge coupled device camera. The results show that the self-pulsing is a mode transition between low-current stage of Townsend discharge and high-current stage of glow discharge. During the self-pulsing, the current rising time relates to the dissipation of space charges, and the decay time relates to the reconstruction of the virtual anode by the accumulation ofmore » positive ions. Whether or not space charges can form and keep the virtual anode is responsible for the discharge mode and hence plays an important role in the self-pulsing phenomenon in low current hollow cathode discharge.« less

Rydberg gas theory of a glow discharge plasma: I. Application to the electrical behaviour of a fast flowing glow discharge plasma.

PubMed

Mason, Rod S; Mitchell, David J; Dickinson, Paul M

2010-04-21

Current-voltage (I-V) curves have been measured, independent of the main discharge, for electricity passing through the steady state fast flowing 'afterglow' plasma of a low power dc glow discharge in Ar. Voltage profiles along the axial line of conduction have been mapped using fixed probes and potentiometry, and the mass spectra of cations emerging from the downstream sampling Cone, also acting as a probe anode, were recorded simultaneously. Floating double probe experiments were also carried out. The electrical behavior is consistent with the well established I-V characteristics of such discharges, but does not comply with classical plasma theory predictions. The plasma decays along the line of conduction, with a lifetime of approximately 1 ms, despite carrying a steady state current, and its potential is below that of the large surface area anode voltage; a situation which cannot exist in the presence of a conventional free ion-electron plasma, unless the electron temperature is super cold. Currents, large by comparison with the main discharge current, and independent of it, are induced to flow through the downstream plasma, from the Anode (acting as a cathode) to the anodic ion exit Cone, induced by electron impact ionisation at the anode, but without necessarily increasing the plasma density. It appears to be conducted by direct charge transfer between a part of the anode surface (acting as cathode to the auxiliary circuit) and the plasma, without secondary electron emission or heating, which suggests the direct involvement of Rydberg atom intermediates. The reaction energy defect (= the work function of the electrode surface) fits with the plasma potential threshold observed for the cathodic reaction to occur. A true free ion-electron plasma is readily detected by the observation of cations at the anode surface, when induced at the downstream anode, at high bias voltages, by the electron impact ionisation in the boundary region. In contrast to the classical model, the complex electrical (and mass spectrometric) behaviour fits qualitatively, but can be understood well, with the Rydberg gas model described in papers II and III (R. S. Mason, and R. S. Mason and P. Douglas, PCCP, 2010, DOI: 10.1039/b918081h and b918083d) over a wide range of probe bias voltages. The full cycle of behavior is then described for the development of a true secondary discharge within the downstream plasma.

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 μW 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.

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

DOEpatents

Duckworth, D.C.; Marcus, R.K.; Donohue, D.L.; Lewis, T.A.

1994-06-28

A high voltage accelerating potential, which is supplied by a high voltage direct current power supply, is applied to the electrically conducting interior wall of an RF powered glow discharge cell. The RF power supply desirably is electrically grounded, and the conductor carrying the RF power to the sample held by the probe is desirably shielded completely excepting only the conductor's terminal point of contact with the sample. The high voltage DC accelerating potential is not supplied to the sample. A high voltage capacitance is electrically connected in series between the sample on the one hand and the RF power supply and an impedance matching network on the other hand. The high voltage capacitance isolates the high DC voltage from the RF electronics, while the RF potential is passed across the high voltage capacitance to the plasma. An inductor protects at least the RF power supply, and desirably the impedance matching network as well, from a short that might occur across the high voltage capacitance. The discharge cell and the probe which holds the sample are configured and disposed to prevent the probe's components, which are maintained at ground potential, from bridging between the relatively low vacuum region in communication with the glow discharge maintained within the cell on the one hand, and the relatively high vacuum region surrounding the probe and cell on the other hand. The probe and cell also are configured and disposed to prevent the probe's components from electrically shorting the cell's components. 11 figures.

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

DOEpatents

Duckworth, Douglas C.; Marcus, R. Kenneth; Donohue, David L.; Lewis, Trousdale A.

1994-01-01

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

MMW/THz imaging using upconversion to visible, based on glow discharge detector array and CCD camera

NASA Astrophysics Data System (ADS)

Aharon, Avihai; Rozban, Daniel; Abramovich, Amir; Yitzhaky, Yitzhak; Kopeika, Natan S.

2017-10-01

An inexpensive upconverting MMW/THz imaging method is suggested here. The method is based on glow discharge detector (GDD) and silicon photodiode or simple CCD/CMOS camera. The GDD was previously found to be an excellent room-temperature MMW radiation detector by measuring its electrical current. The GDD is very inexpensive and it is advantageous due to its wide dynamic range, broad spectral range, room temperature operation, immunity to high power radiation, and more. An upconversion method is demonstrated here, which is based on measuring the visual light emitting from the GDD rather than its electrical current. The experimental setup simulates a setup that composed of a GDD array, MMW source, and a basic CCD/CMOS camera. The visual light emitting from the GDD array is directed to the CCD/CMOS camera and the change in the GDD light is measured using image processing algorithms. The combination of CMOS camera and GDD focal plane arrays can yield a faster, more sensitive, and very inexpensive MMW/THz camera, eliminating the complexity of the electronic circuits and the internal electronic noise of the GDD. Furthermore, three dimensional imaging systems based on scanning prohibited real time operation of such imaging systems. This is easily solved and is economically feasible using a GDD array. This array will enable us to acquire information on distance and magnitude from all the GDD pixels in the array simultaneously. The 3D image can be obtained using methods like frequency modulation continuous wave (FMCW) direct chirp modulation, and measuring the time of flight (TOF).

Application of Direct Current Atmospheric Pressure Glow Microdischarge Generated in Contact with a Flowing Liquid Solution for Synthesis of Au-Ag Core-Shell Nanoparticles

PubMed Central

Dzimitrowicz, Anna; Jamroz, Piotr; Nyk, Marcin; Pohl, Pawel

2016-01-01

A direct current atmospheric pressure glow microdischarge (dc-μAPGD) generated between an Ar nozzle microjet and a flowing liquid was applied to produce Au-Ag core-shell nanoparticles (Au@AgCSNPs) in a continuous flow system. Firstly, operating dc-μAPGD with the flowing solution of the Au(III) ions as the cathode, the Au nanoparticles (AuNPs) core was produced. Next, to produce the core-shell nanostructures, the collected AuNPs solution was immediately mixed with an AgNO3 solution and passed through the system with the reversed polarity to fabricate the Ag nanoshell on the AuNPs core. The formation of Au@AgCSNPs was confirmed using ultraviolet-visible (UV-Vis) absorbance spectrophotometry, transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDS). Three localized surface plasmon resonance absorption bands with wavelengths centered at 372, 546, and 675 nm were observed in the UV-Vis spectrum of Au@AgCSNPs, confirming the reduction of both the Au(III) and Ag(I) ions. The right configuration of metals in Au@AgCSNPs was evidenced by TEM. The Au core diameter was 10.2 ± 2.0 nm, while the thickness of the Ag nanoshell was 5.8 ± 1.8 nm. The elemental composition of the bimetallic nanoparticles was also confirmed by EDS. It is possible to obtain 90 mL of a solution containing Au@AgCSNPs per hour using the applied microdischarge system. PMID:28773393

Particle in cell/Monte Carlo collision analysis of the problem of identification of impurities in the gas by the plasma electron spectroscopy method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kusoglu Sarikaya, C.; Rafatov, I., E-mail: rafatov@metu.edu.tr; Kudryavtsev, A. A.

2016-06-15

The work deals with the Particle in Cell/Monte Carlo Collision (PIC/MCC) analysis of the problem of detection and identification of impurities in the nonlocal plasma of gas discharge using the Plasma Electron Spectroscopy (PLES) method. For this purpose, 1d3v PIC/MCC code for numerical simulation of glow discharge with nonlocal electron energy distribution function is developed. The elastic, excitation, and ionization collisions between electron-neutral pairs and isotropic scattering and charge exchange collisions between ion-neutral pairs and Penning ionizations are taken into account. Applicability of the numerical code is verified under the Radio-Frequency capacitively coupled discharge conditions. The efficiency of the codemore » is increased by its parallelization using Open Message Passing Interface. As a demonstration of the PLES method, parallel PIC/MCC code is applied to the direct current glow discharge in helium doped with a small amount of argon. Numerical results are consistent with the theoretical analysis of formation of nonlocal EEDF and existing experimental data.« less

Io in Eclipse 2

NASA Technical Reports Server (NTRS)

2007-01-01

This image of Io eclipsed by Jupiter's shadow is a combination of several images taken by the New Horizons Long Range Reconnaissance Imager (LORRI) between 09:35 and 09:41 Universal Time on February 27, 2007, about 28 hours after the spacecraft's closest approach to Jupiter. North is at the top of the image.

In the darkness, only glowing hot lava, auroral displays in Io's tenuous atmosphere and the moon's volcanic plumes are visible. The brightest points of light in the image are the glow of incandescent lava at several active volcanoes. The three brightest volcanoes south of the equator are, from left to right, Pele, Reiden and Marduk. North of the equator, near the disk center, a previously unknown volcano near 22 degrees north, 233 degrees west glows brightly. (The dark streak to its right is an artifact.)

The edge of Io's disk is outlined by the auroral glow produced as intense radiation from Jupiter's magnetosphere bombards the atmosphere. The glow is patchy because the atmosphere itself is patchy, being denser over active volcanoes. At the 1 o'clock position the giant glowing plume from the Tvashtar volcano rises 330 kilometers (200 miles) above the edge of the disk, and several smaller plumes are also visible as diffuse glows scattered across the disk. Bright glows at the edge of Io on the left and right sides of the disk mark regions where electrical currents connect Io to Jupiter's magnetosphere.

New Horizons was 2.8 million kilometers (1.7 million miles) from Io when this picture was taken, and the image is centered at Io coordinates 2 degrees south, 238 degrees west. The image has been heavily processed to remove scattered light from Jupiter, but some artifacts remain, including a horizontal seam where two sets of frames were pieced together. Total exposure time for this image was 56 seconds.

Io in Eclipse

NASA Technical Reports Server (NTRS)

2007-01-01

This unusual image shows Io glowing in the darkness of Jupiter's shadow. It is a combination of eight images taken by the New Horizons Long Range Reconnaissance Imager (LORRI) between 14:25 and 14:55 Universal Time on February 27, 2007, about 15 hours before the spacecraft's closest approach to Jupiter. North is at the top of the image.

Io's surface is invisible in the darkness, but the image reveals glowing hot lava, auroral displays in Io's tenuous atmosphere and volcanic plumes across the moon. The three bright points of light on the right side of Io are incandescent lava at active volcanoes - Pele and Reiden (south of the equator), and a previously unknown volcano near 22 degrees north, 233 degrees west near the edge of the disk at the 2 o'clock position.

An auroral glow, produced as intense radiation from Jupiter's magnetosphere bombards Io's atmosphere, outlines the edge of the moon's disk. The glow is patchy because the atmosphere itself is patchy, being denser over active volcanoes. In addition to the near-surface glow, there is a remarkable auroral glow suspended 330 kilometers (200 miles) above the edge of the disk at the 2 o'clock position; perhaps this glowing gas was ejected from the new volcano below it. Another glowing gas plume, above a fainter point of light, is visible just inside Io's disk near the 6 o'clock position; this plume is above another new volcanic eruption discovered by New Horizons.

On the left side of the disk, near Io's equator, a cluster of faint dots of light is centered near the point on Io that always faces Jupiter. This is the region where electrical currents connect Io to Jupiter's magnetosphere. It is likely that electrical connections to individual volcanoes are causing the glows seen here, though the details are mysterious.

Total exposure time for this image was 16 seconds. The range to Io was 2.8 million kilometers (1.7 million miles), and the image is centered at Io coordinates 7 degrees south, 306 degrees west. The image has been heavily processed to remove scattered light from Jupiter, but some artifacts remain, such as dark patches in the background.

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

Spectral Evidence for Ionization in Air-Filled Glow Discharge Tubes: Application to Sprites

NASA Astrophysics Data System (ADS)

Armstrong, R. A.; Williams, E. R.; Golka, R. K.; Williams, D. R.

2001-12-01

The question of ionization in sprites and the evidence for VLF backscatter from sprites has motivated a quantitative spectral analysis of the various (classical) regions of the glow discharge tube under DC excitation and at air densities appropriate for sprites in the mesosphere. A PR-650 colorimeter (Photo Research, Inc.) has enabled calibrated irradiance measurements for localized zones along the axis of the discharge tube--in the dominantly blue negative glow, in the Faraday dark space and in the red/pink positive column. Consistent with historical nomenclature, nitrogen first and second positive emission is dominant in the positive column (associated with neutral N2), and nitrogen first negative emission, with a prominent peak at 4278 A, is dominant in the blue negative glow (associated with ionized N2+). Whereas nitrogen first and second positive emission are also detected in the negative glow, no spectral evidence for ionization (no 4279, no 3914, no Meinel) is found in the red/pink positive column. This negative result is attributed not to an absence of ionization in the positive column, but rather to a sparse population of N2+ relative to neutral nitrogen in this region, and to the prominent emission in the blue part of the spectrum due to nitrogen second positive. A similar interpretation may be appropriate for the time-integrated spectra from the red body of sprites, also lacking direct evidence for ionization.

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.

Target Glow Analysis Program for Air Force Maui Optical Station

DTIC Science & Technology

1993-06-15

organization, please norif.PrSI, Hanscom AFB, MA 01731-3010. This will assist us in maintaining a current mailing list. Do not return copies of this report...34 Ottice o! mAafaernert a" ,uCe:. Paperwork Reduction Project (0704-018). Washington. DC 2003. 1. AGENCY USE ONLY L~eave blank) 2. REPORT DATE 3. REPORT TYPE...Interactions Technology research to observe and analyze the glow surrounding space- craft using the AMOS ground-based telescope facility. This unique

Cold starting of fluorescent lamps - part I: a description of the transient regime

NASA Astrophysics Data System (ADS)

Langer, Reinhard; Garner, Richard; Paul, Irina; Horn, Siegfried; Tidecks, Reinhard

2016-10-01

In this paper we give a proposal for the transient behaviour of a cold-started fluorescent lamp, from the generation of the first conductive channel over the normal and abnormal glow discharge and the glow-to-arc (GTA) transition to the arc discharge in the steady state. Starting from the equilibrium voltage-current characteristics of the lamp and considering recent experimental results a qualitative description of the transient regime is developed, which was so far not available in the literature.

Two-dimensional hybrid Monte Carlo–fluid modelling of dc glow discharges: Comparison with fluid models, reliability, and accuracy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eylenceoğlu, E.; Rafatov, I., E-mail: rafatov@metu.edu.tr; Kudryavtsev, A. A.

2015-01-15

Two-dimensional hybrid Monte Carlo–fluid numerical code is developed and applied to model the dc glow discharge. The model is based on the separation of electrons into two parts: the low energetic (slow) and high energetic (fast) electron groups. Ions and slow electrons are described within the fluid model using the drift-diffusion approximation for particle fluxes. Fast electrons, represented by suitable number of super particles emitted from the cathode, are responsible for ionization processes in the discharge volume, which are simulated by the Monte Carlo collision method. Electrostatic field is obtained from the solution of Poisson equation. The test calculations weremore » carried out for an argon plasma. Main properties of the glow discharge are considered. Current-voltage curves, electric field reversal phenomenon, and the vortex current formation are developed and discussed. The results are compared to those obtained from the simple and extended fluid models. Contrary to reports in the literature, the analysis does not reveal significant advantages of existing hybrid methods over the extended fluid model.« less

Micro glow plasma for localized nanostructural modification of carbon nanotube forest

NASA Astrophysics Data System (ADS)

Sarwar, Mirza Saquib us; Xiao, Zhiming; Saleh, Tanveer; Nojeh, Alireza; Takahata, Kenichi

2016-08-01

This paper reports the localized selective treatment of vertically aligned carbon nanotubes, or CNT forests, for radial size modification of the nanotubes through a micro-scale glow plasma established on the material. An atmospheric-pressure DC glow plasma is shown to be stably sustained on the surface of the CNT forest in argon using micromachined tungsten electrodes with diameters down to 100 μm. Experiments reveal thinning or thickening of the nanotubes under the micro glow depending on the process conditions including discharge current and process time. These thinning and thickening effects in the treated nanotubes are measured to be up to ˜30% and ˜300% in their diameter, respectively, under the tested conditions. The elemental and Raman analyses suggest that the treated region of the CNT forest is pure carbon and maintains a degree of crystallinity. The local plasma treatment process investigated may allow modification of material characteristics in different domains for targeted regions or patterns, potentially aiding custom design of micro-electro-mechanical systems and other emerging devices enabled by the CNT forest.

Micro glow plasma for localized nanostructural modification of carbon nanotube forest

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sarwar, Mirza Saquib us; Xiao, Zhiming; Saleh, Tanveer

2016-08-22

This paper reports the localized selective treatment of vertically aligned carbon nanotubes, or CNT forests, for radial size modification of the nanotubes through a micro-scale glow plasma established on the material. An atmospheric-pressure DC glow plasma is shown to be stably sustained on the surface of the CNT forest in argon using micromachined tungsten electrodes with diameters down to 100 μm. Experiments reveal thinning or thickening of the nanotubes under the micro glow depending on the process conditions including discharge current and process time. These thinning and thickening effects in the treated nanotubes are measured to be up to ∼30% andmore » ∼300% in their diameter, respectively, under the tested conditions. The elemental and Raman analyses suggest that the treated region of the CNT forest is pure carbon and maintains a degree of crystallinity. The local plasma treatment process investigated may allow modification of material characteristics in different domains for targeted regions or patterns, potentially aiding custom design of micro-electro-mechanical systems and other emerging devices enabled by the CNT forest.« less

Sustained diffusive alternating current gliding arc discharge in atmospheric pressure air

NASA Astrophysics Data System (ADS)

Zhu, Jiajian; Gao, Jinlong; Li, Zhongshan; Ehn, Andreas; Aldén, Marcus; Larsson, Anders; Kusano, Yukihiro

2014-12-01

Rapid transition from glow discharge to thermal arc has been a common problem in generating stable high-power non-thermal plasmas especially at ambient conditions. A sustained diffusive gliding arc discharge was generated in a large volume in atmospheric pressure air, driven by an alternating current (AC) power source. The plasma column extended beyond the water-cooled stainless steel electrodes and was stabilized by matching the flow speed of the turbulent air jet with the rated output power. Comprehensive investigations were performed using high-speed movies measured over the plasma column, synchronized with simultaneously recorded current and voltage waveforms. Dynamic details of the novel non-equilibrium discharge are revealed, which is characterized by a sinusoidal current waveform with amplitude stabilized at around 200 mA intermediate between thermal arc and glow discharge, shedding light to the governing mechanism of the sustained spark-suppressed AC gliding arc discharge.

The Conductor-Dielectric Junctions in a Low Density Plasma

NASA Technical Reports Server (NTRS)

Vayner, Boris; Galofaro, Joel; Ferguson, Dale; deGroot, Wim; Thomson, Clint; Dennison, J. R.; Davies, Robert

1999-01-01

A conductor-dielectric junction exposed to the space environment is a frequent spacecraft design feature. Due to spacecraft charging and/or solar array operation, the conductor can acquire a high potential with respect to the surrounding plasma. If this potential is positive the insulators adjacent to exposed conductors can collect current as if they were conductors themselves. This phenomenon, called snapover, results in a substantial increase in current collection, and may even result in a glow discharge if the potential is high enough. If a conductor has a negative potential, arcing can occur at the site of a junction. Both of these phenomena negatively affect spacecraft operation. To prevent negative consequences, the physical mechanisms of snapover and arc inception require investigation. In this paper, results are presented of an experimental and theoretical study of snapover, glow discharge, and arc phenomena for different materials immersed in argon or xenon plasmas. The effect of snapover is investigated for several metal-dielectric junctions: copper-teflon, copper-Kapton, copper-glass, aluminum-teflon, aluminum-Kapton, steel-teflon, anodized aluminum with pinholes, and copper-ceramics. I-V curves are measured and snapover inception voltages, essential parameters (increase in current and collection area due to secondary electrons), and glow discharge inception thresholds are determined. Optical spectra are obtained for glow discharges in both argon and xenon plasmas. These spectra provide information regarding atomic species entrapped in the glow region. Some spectral lines can be used to estimate plasma parameters in the discharge area. A video-camera and linear array were used to confirm that snapover inception is accompanied by very low intensity visible light emission. This result seems to be important for the estimate of the light pollution around spacecraft. Optical spectra (wavelengths 380-650 nm) of arcs are also obtained on a negatively biased chromic acid anodized aluminum plate immersed in low density argon and xenon plasmas. Analysis of these spectra confirms our earlier findings that aluminum atoms are ejected from the arc site. Moreover, it is found that chromium atoms are also quite abundant in the arc plasma. It is believed that the latter results contribute considerably to the understanding of processes of plasma contamination caused by arcing.

Physical mechanisms of self-organization and formation of current patterns in gas discharges of the Townsend and glow types

DOE Office of Scientific and Technical Information (OSTI.GOV)

Raizer, Yu. P.; Mokrov, M. S.

The paper discusses current filamentation and formation of current structures (in particular, hexagonal current patterns) in discharges of the Townsend and glow types. The aim of the paper, which is in part a review, is to reveal basic reasons for formation of current patterns in different cases, namely, in dielectric barrier discharge, discharge with semiconductor cathode, and micro-discharge between metallic electrodes. Pursuing this goal, we give a very brief review of observations and discuss only those theoretical, computational, and experimental papers that shed light on the physical mechanisms involved. The mechanisms are under weak currents—the thermal expansion of the gasmore » as a result of Joule heating; under enhanced currents—the electric field and ionization rate redistribution induced by space charge. Both mechanisms lead to instability of the homogeneous discharges. In addition, we present new results of numerical simulations of observed short-living current filaments which are chaotic in space and time.« less

The influence of stabilizers on the production of gold nanoparticles by direct current atmospheric pressure glow microdischarge generated in contact with liquid flowing cathode.

PubMed

Dzimitrowicz, Anna; Jamroz, Piotr; Greda, Krzysztof; Nowak, Piotr; Nyk, Marcin; Pohl, Pawel

Gold nanoparticles (Au NPs) were prepared by direct current atmospheric pressure glow microdischarge (dc-μAPGD) generated between a miniature argon flow microjet and a flowing liquid cathode. The applied discharge system was operated in a continuous flow liquid mode. The influence of various stabilizers added to the solution of the liquid cathode, i.e., gelatin (GEL), polyvinylpyrrolidone (PVP), or polyvinyl alcohol (PVA), as well as the concentration of the Au precursor (chloroauric acid, HAuCl 4 ) in the solution on the production growth of Au NPs was investigated. Changes in the intensity of the localized surface plasmon resonance (LSPR) band in UV/Vis absorption spectra of solutions treated by dc-μAPGD and their color were observed. The position and the intensity of the LSPR band indicated that relatively small nanoparticles were formed in solutions containing GEL as a capping agent. In these conditions, the maximum of the absorption LSPR band was at 531, 534, and 535 nm, respectively, for 50, 100, and 200 mg L -1 of Au. Additionally, scanning electron microscopy (SEM) and dynamic light scattering (DLS) were used to analyze the structure and the morphology of obtained Au NPs. The shape of Au NPs was spherical and uniform. Their mean size was ca. 27, 73, and 92 nm, while the polydispersity index was 0.296, 0.348, and 0.456 for Au present in the solution of the flowing liquid cathode at a concentration of 50, 100, and 200 mg L -1 , respectively. The production rate of synthesized Au NPs depended on the precursor concentration with mean values of 2.9, 3.5, and 5.7 mg h -1 , respectively.

The influence of stabilizers on the production of gold nanoparticles by direct current atmospheric pressure glow microdischarge generated in contact with liquid flowing cathode

NASA Astrophysics Data System (ADS)

Dzimitrowicz, Anna; Jamroz, Piotr; Greda, Krzysztof; Nowak, Piotr; Nyk, Marcin; Pohl, Pawel

2015-04-01

Gold nanoparticles (Au NPs) were prepared by direct current atmospheric pressure glow microdischarge (dc-μAPGD) generated between a miniature argon flow microjet and a flowing liquid cathode. The applied discharge system was operated in a continuous flow liquid mode. The influence of various stabilizers added to the solution of the liquid cathode, i.e., gelatin (GEL), polyvinylpyrrolidone (PVP), or polyvinyl alcohol (PVA), as well as the concentration of the Au precursor (chloroauric acid, HAuCl4) in the solution on the production growth of Au NPs was investigated. Changes in the intensity of the localized surface plasmon resonance (LSPR) band in UV/Vis absorption spectra of solutions treated by dc-μAPGD and their color were observed. The position and the intensity of the LSPR band indicated that relatively small nanoparticles were formed in solutions containing GEL as a capping agent. In these conditions, the maximum of the absorption LSPR band was at 531, 534, and 535 nm, respectively, for 50, 100, and 200 mg L-1 of Au. Additionally, scanning electron microscopy (SEM) and dynamic light scattering (DLS) were used to analyze the structure and the morphology of obtained Au NPs. The shape of Au NPs was spherical and uniform. Their mean size was ca. 27, 73, and 92 nm, while the polydispersity index was 0.296, 0.348, and 0.456 for Au present in the solution of the flowing liquid cathode at a concentration of 50, 100, and 200 mg L-1, respectively. The production rate of synthesized Au NPs depended on the precursor concentration with mean values of 2.9, 3.5, and 5.7 mg h-1, respectively.

The smooth transition from field emission to a self-sustained plasma in microscale electrode gaps at atmospheric pressure

NASA Astrophysics Data System (ADS)

Bilici, Mihai A.; Haase, John R.; Boyle, Calvin R.; Go, David B.; Sankaran, R. Mohan

2016-06-01

We report on the existence of a smooth transition from field emission to a self-sustained plasma in microscale electrode geometries at atmospheric pressure. This behavior, which is not found at macroscopic scales or low pressures, arises from the unique combination of large electric fields that are created in microscale dimensions to produce field-emitted electrons and the high pressures that lead to collisional ionization of the gas. Using a tip-to-plane electrode geometry, currents less than 10 μA are measured at onset voltages of ˜200 V for gaps less than 5 μm, and analysis of the current-voltage (I-V) relationship is found to follow Fowler-Nordheim behavior, confirming field emission. As the applied voltage is increased, gas breakdown occurs smoothly, initially resulting in the formation of a weak, partial-like glow and then a self-sustained glow discharge. Remarkably, this transition is essentially reversible, as no significant hysteresis is observed during forward and reverse voltage sweeps. In contrast, at larger electrode gaps, no field emission current is measured and gas breakdown occurs abruptly at higher voltages of ˜400 V, absent of any smooth transition from the pre-breakdown condition and is characterized only by glow discharge formation.

Influence of an electric probe on the anode layer of a glow discharge in nitrogen

NASA Astrophysics Data System (ADS)

Taran, M. D.; Dyatko, N. A.; Kochetov, I. V.; Napartovich, A. P.; Akishev, Yu S.

2018-05-01

A two-dimensional (2D) numerical model of a DC glow discharge in nitrogen is developed for the case when the electric probe is mounted in the discharge gap. Within this model, calculations are performed for the gas pressure of 50 Torr and discharge current densities of 22 and 90 mA cm‑2. A cylindrical probe 1 mm in diameter is located parallel to the anode at a distance of 5 or 10 mm. The probe potential is varied in a wide range relative to the floating potential. Numerical simulations predict the 2D plasma perturbation pattern induced by the electric probe and the influence of the probe on anode layer characteristics. In particular, conditions are determined under which a region with no glow forms in the anode layer.

Pulsed microdischarge with inductively coupled plasma mass spectrometry for elemental analysis on solid metal samples.

PubMed

Li, Weifeng; Yin, Zhibin; Cheng, Xiaoling; Hang, Wei; Li, Jianfeng; Huang, Benli

2015-05-05

Pulsed microdischarge employed as source for direct solid analysis was investigated in N2 environment at atmospheric pressure. Compared with direct current (DC) microdischarge, it exhibits advantages with respect to the ablation and emission of the sample. Comprehensive evidence, including voltage-current relationship, current density (j), and electron density (ne), suggests that pulsed microdischarge is in the arc regime while DC microdischarge belongs to glow. Capability in ablating metal samples demonstrates that pulsed microdischarge is a viable option for direct solid sampling because of the enhanced instantaneous energy. Using optical spectrometer, only common emission lines of N2 can be acquired in DC mode, whereas primary atomic and ionic lines of the sample are obtained in the case of pulsed mode. Calculations show a significant difference in N2 vibrational temperatures between DC and pulsed microdischarge. Combined with inductively coupled plasma mass spectrometry (ICPMS), pulsed microdischarge exhibits much better performances in calibration linearity and limits of detection (LOD) than those of DC discharge in direct analysis of samples of different matrices. To improve transmission efficiency, a mixture of Ar and N2 was employed as discharge gas as well as carrier gas in follow-up experiments, facilitating that LODs of most elements reached ng/g.

A uniform laminar air plasma plume with large volume excited by an alternating current voltage

NASA Astrophysics Data System (ADS)

Li, Xuechen; Bao, Wenting; Chu, Jingdi; Zhang, Panpan; Jia, Pengying

2015-12-01

Using a plasma jet composed of two needle electrodes, a laminar plasma plume with large volume is generated in air through an alternating current voltage excitation. Based on high-speed photography, a train of filaments is observed to propagate periodically away from their birth place along the gas flow. The laminar plume is in fact a temporal superposition of the arched filament train. The filament consists of a negative glow near the real time cathode, a positive column near the real time anode, and a Faraday dark space between them. It has been found that the propagation velocity of the filament increases with increasing the gas flow rate. Furthermore, the filament lifetime tends to follow a normal distribution (Gaussian distribution). The most probable lifetime decreases with increasing the gas flow rate or decreasing the averaged peak voltage. Results also indicate that the real time peak current decreases and the real time peak voltage increases with the propagation of the filament along the gas flow. The voltage-current curve indicates that, in every discharge cycle, the filament evolves from a Townsend discharge to a glow one and then the discharge quenches. Characteristic regions including a negative glow, a Faraday dark space, and a positive column can be discerned from the discharge filament. Furthermore, the plasma parameters such as the electron density, the vibrational temperature and the gas temperature are investigated based on the optical spectrum emitted from the laminar plume.

Direct current plasma jet at atmospheric pressure operating in nitrogen and air

NASA Astrophysics Data System (ADS)

Deng, X. L.; Nikiforov, A. Yu.; Vanraes, P.; Leys, Ch.

2013-01-01

An atmospheric pressure direct current (DC) plasma jet is investigated in N2 and dry air in terms of plasma properties and generation of active species in the active zone and the afterglow. The influence of working gases and the discharge current on plasma parameters and afterglow properties are studied. The electrical diagnostics show that discharge can be sustained in two different operating modes, depending on the current range: a self-pulsing regime at low current and a glow regime at high current. The gas temperature and the N2 vibrational temperature in the active zone of the jet and in the afterglow are determined by means of emission spectroscopy, based on fitting spectra of N2 second positive system (C3Π-B3Π) and the Boltzmann plot method, respectively. The spectra and temperature differences between the N2 and the air plasma jet are presented and analyzed. Space-resolved ozone and nitric oxide density measurements are carried out in the afterglow of the jet. The density of ozone, which is formed in the afterglow of nitrogen plasma jet, is quantitatively detected by an ozone monitor. The density of nitric oxide, which is generated only in the air plasma jet, is determined by means of mass-spectroscopy techniques.

Passage of the discharge current through the plasma-electrode interface in the electromagnetic rail accelerator channel

NASA Astrophysics Data System (ADS)

Zhukov, B. G.; Reznikov, B. I.; Kurakin, R. O.; Ponyaev, S. A.; Bobashev, S. V.

2016-11-01

We investigate the phenomena that accompany the acceleration of a free plasma piston (without a striker) in the electromagnetic rail accelerator channel filled with different gases (argon, helium). An intense glow appears in the shock-compressed layer (SCL) in the case of strong shock waves that produce a high electron concentration ( 1017-1018 cm-3) behind the front. We have proposed that explosive electron emission (EEE) ensures the high-intensity emission of electrons, the passage of a part of the discharge current through the SCL, and the glow of the SCL. The velocity of a shock wave for which the strong electric field in the Debye layer at the cathode causes EEE from its surface and the passage of the current in the SCL has been determined. It has been concluded that, for high velocities of the plasma, the EEE is a universal mechanism that ensure the passage of a strong current through the interface between the cold electrode and the plasma.

Sensitive glow discharge ion source for aerosol and gas analysis

DOEpatents

Reilly, Peter T. A. [Knoxville, TN

2007-08-14

A high sensitivity glow discharge ion source system for analyzing particles includes an aerodynamic lens having a plurality of constrictions for receiving an aerosol including at least one analyte particle in a carrier gas and focusing the analyte particles into a collimated particle beam. A separator separates the carrier gas from the analyte particle beam, wherein the analyte particle beam or vapors derived from the analyte particle beam are selectively transmitted out of from the separator. A glow discharge ionization source includes a discharge chamber having an entrance orifice for receiving the analyte particle beam or analyte vapors, and a target electrode and discharge electrode therein. An electric field applied between the target electrode and discharge electrode generates an analyte ion stream from the analyte vapors, which is directed out of the discharge chamber through an exit orifice, such as to a mass spectrometer. High analyte sensitivity is obtained by pumping the discharge chamber exclusively through the exit orifice and the entrance orifice.

Quantum machine learning with glow for episodic tasks and decision games

NASA Astrophysics Data System (ADS)

Clausen, Jens; Briegel, Hans J.

2018-02-01

We consider a general class of models, where a reinforcement learning (RL) agent learns from cyclic interactions with an external environment via classical signals. Perceptual inputs are encoded as quantum states, which are subsequently transformed by a quantum channel representing the agent's memory, while the outcomes of measurements performed at the channel's output determine the agent's actions. The learning takes place via stepwise modifications of the channel properties. They are described by an update rule that is inspired by the projective simulation (PS) model and equipped with a glow mechanism that allows for a backpropagation of policy changes, analogous to the eligibility traces in RL and edge glow in PS. In this way, the model combines features of PS with the ability for generalization, offered by its physical embodiment as a quantum system. We apply the agent to various setups of an invasion game and a grid world, which serve as elementary model tasks allowing a direct comparison with a basic classical PS agent.

Two-dimensional electrodynamic structure of the normal glow discharge in an axial magnetic field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Surzhikov, S. T., E-mail: surg@ipmnet.ru

Results are presented from numerical simulations of an axisymmetric normal glow discharge in molecular hydrogen and molecular nitrogen in an axial magnetic field. The charged particle densities and averaged azimuthal rotation velocities of electrons and ions are studied as functions of the gas pressure in the range of 1–5 Torr, electric field strength in the range of 100–600 V/cm, and magnetic field in the range of 0.01–0.3 T. It is found that the axial magnetic field does not disturb the normal current density law.

Direct determination of arsenic in steel by glow discharge optical emission spectrometry with argon-helium mixed gas.

PubMed

Wagatsuma, Kazuaki

2003-02-01

In glow discharge optical emission spectrometry, an argon-helium mixed gas plasma was investigated to improve the detection sensitivity of arsenic in steel samples. The emission line of arsenic was enhanced and the background intensity was simultaneously reduced when an Ar-He plasma was employed instead of an Ar plasma, which is effective for the sensitive determination of arsenic. The detection limits were calculated to be 0.009 mass% for a 700-V Ar plasma, 0.004 mass% for a 700-V Ar-He plasma, and 0.001 mass% for a 900-V Ar-He plasma.

Measurement of Electron Density and Ion Collision Frequency with Dual Assisted Grounded Electrode DBD in Atmospheric Pressure Helium Plasma Jet

NASA Astrophysics Data System (ADS)

Zhou, Qiujiao; Qi, Bing; Huang, Jianjun; Pan, Lizhu; Liu, Ying

2016-04-01

The properties of a helium atmospheric-pressure plasma jet (APPJ) are diagnosed with a dual assisted grounded electrode dielectric barrier discharge device. In the glow discharge, we captured the current waveforms at the positions of the three grounded rings. From the current waveforms, the time delay between the adjacent positions of the rings is employed to calculate the plasma bullet velocity of the helium APPJ. Moreover, the electron density is deduced from a model combining with the time delay and current intensity, which is about 1011 cm-3. In addition, The ion-neutral particles collision frequency in the radial direction is calculated from the current phase difference between two rings, which is on the order of 107 Hz. The results are helpful for understanding the basic properties of APPJs. supported by National Natural Science Foundation of China (No. 11105093), the Technological Project of Shenzhen, China (No. JC201005280485A), and the Planned S&T Program of Shenzhen, China (No. JC201105170703A)

Current collection by high voltage anodes in near ionospheric conditions

NASA Technical Reports Server (NTRS)

Antoniades, John A.; Greaves, Rod G.; Boyd, D. A.; Ellis, R.

1990-01-01

The authors experimentally identified three distinct regimes with large differences in current collection in the presence of neutrals and weak magnetic fields. In magnetic field/anode voltage space the three regions are separated by very sharp transition boundaries. The authors performed a series of laboratory experiments to study the dependence of the region boundaries on several parameters, such as the ambient neutral density, plasma density, magnetic field strength, applied anode voltage, voltage pulsewidth, chamber material, chamber size and anode radius. The three observed regimes are: classical magnetic field limited collection; stable medium current toroidal discharge; and large scale, high current space glow discharge. There is as much as several orders of magnitude of difference in the amount of collected current upon any boundary crossing, particularly if one enters the space glow regime. They measured some of the properties of the plasma generated by the breakdown that is present in regimes II and III in the vicinity of the anode including the sheath modified electrostatic potential, I-V characteristics at high voltage as well as the local plasma density.

Diffraction of dust acoustic waves by a circular cylinder

NASA Astrophysics Data System (ADS)

Kim, S.-H.; Heinrich, J. R.; Merlino, R. L.

2008-09-01

The diffraction of dust acoustic (DA) waves around a long dielectric rod is observed using video imaging methods. The DA waves are spontaneously excited in a dusty plasma produced in a direct current glow discharge plasma. The rod acquires a negative charge that produces a coaxial dust void around it. The diameter of the void is the effective size of the "obstacle" encountered by the waves. The wavelength of the DA waves is approximately the size of the void. The observations are considered in relation to the classical problem of the diffraction of sound waves from a circular cylinder, a problem first analyzed by Lord Rayleigh [Theory of Sound, 2nd ed. (MacMillan, London, 1896)].

The growing and glowing toolbox of fluorescent and photoactive proteins

PubMed Central

Rodriguez, Erik A.; Campbell, Robert E.; Lin, John Y.; Lin, Michael Z.; Miyawaki, Atsushi; Palmer, Amy E.; Shu, Xiaokun; Zhang, Jin

2016-01-01

Over the past 20 years, protein engineering has been extensively used to improve and modify the fundamental properties of fluorescent proteins (FPs) with the goal of adapting them for a fantastic range of applications. FPs have been modified by a combination of rational design, structure-based mutagenesis, and countless cycles of directed evolution (gene diversification followed by selection of clones with desired properties) that have collectively pushed the properties to photophysical and biochemical extremes. In this review, we attempt to provide both a summary of the progress that has been made during the past two decades, and a broad overview of the current state of FP development and applications in mammalian systems. PMID:27814948

1D kinetic simulations of a short glow discharge in helium

NASA Astrophysics Data System (ADS)

Yuan, Chengxun; Bogdanov, E. A.; Eliseev, S. I.; Kudryavtsev, A. A.

2017-07-01

This paper presents a 1D model of a direct current glow discharge based on the solution of the kinetic Boltzmann equation in the two-term approximation. The model takes into account electron-electron coulomb collisions, the corresponding collision integral is written in both detailed and simplified forms. The Boltzmann equation for electrons is coupled with continuity equations for ions and metastable atoms and the Poisson equation for electric potential. Simulations are carried out self-consistently for the whole length of discharge in helium (from cathode to anode) for cases p = 1 Torr, L = 3.6 cm and p = 20 Torr, L = 1.8 mm, so that pL = 3.6 cm.Torr in both cases. It is shown that simulations based on the kinetic approach give lower values of electron temperature in plasma than fluid simulations. Peaks in spatial differential flux corresponding to the electrons originating from superelastic collisions and Penning ionization were observed in simulations. Different approaches of taking coulomb collisions into account give significantly different values of electron density and electron temperature in plasma. Analysis showed that using a simplified approach gives a non-zero contribution to the electron energy balance, which is comparable to energy losses on elastic and inelastic collisions and leads to significant errors and thus is not recommended.

Numerical modeling of a glow discharge through a supersonic bow shock in air

NASA Astrophysics Data System (ADS)

Rassou, S.; Packan, D.; Elias, P.-Q.; Tholin, F.; Chemartin, L.; Labaune, J.

2017-03-01

The interaction between a glow discharge and the bow shock of a Mach 3 air flow around a truncated conical model with a central spike is modeled, and comparison is made with prior experimental results. The KRONOS workflow for plasma modeling in flow fields, which has recently been developed at ONERA, was used for the modeling. Based on the quasi-neutral approximation, it couples hypersonic and reactive flow fields with electron chemistry, including the effect of non-Maxwellian electron energy distribution function. The model used for the discharge involves 12 species and 82 reactions, including ionization, electronic and vibrational excitation, and attachment. The simulations reproduce the main features of the discharge observed experimentally well, in particular, the very recognizable topology of the discharge. It was found from the simulations that behind the bow shock, in the afterglow, the negative ion flow ensures the electrical conduction and the establishment of the glow discharge. The influence of kinetic rates on the voltage-current characteristics is discussed.

Powerful glow discharge excilamp

DOEpatents

Tarasenko, Victor F.; Panchenko, Aleksey N.; Skakun, Victor S.; Sosnin, Edward A.; Wang, Francis T.; Myers, Booth R.; Adamson, Martyn G.

2002-01-01

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

Glowing locked nucleic acids: brightly fluorescent probes for detection of nucleic acids in cells.

PubMed

Østergaard, Michael E; Cheguru, Pallavi; Papasani, Madhusudhan R; Hill, Rodney A; Hrdlicka, Patrick J

2010-10-13

Fluorophore-modified oligonucleotides have found widespread use in genomics and enable detection of single-nucleotide polymorphisms, real-time monitoring of PCR, and imaging of mRNA in living cells. Hybridization probes modified with polarity-sensitive fluorophores and molecular beacons (MBs) are among the most popular approaches to produce hybridization-induced increases in fluorescence intensity for nucleic acid detection. In the present study, we demonstrate that the 2'-N-(pyren-1-yl)carbonyl-2'-amino locked nucleic acid (LNA) monomer X is a highly versatile building block for generation of efficient hybridization probes and quencher-free MBs. The hybridization and fluorescence properties of these Glowing LNA probes are efficiently modulated and optimized by changes in probe backbone chemistry and architecture. Correctly designed probes are shown to exhibit (a) high affinity toward RNA targets, (b) excellent mismatch discrimination, (c) high biostability, and (d) pronounced hybridization-induced increases in fluorescence intensity leading to formation of brightly fluorescent duplexes with unprecedented emission quantum yields (Φ(F) = 0.45-0.89) among pyrene-labeled oligonucleotides. Finally, specific binding between messenger RNA and multilabeled quencher-free MBs based on Glowing LNA monomers is demonstrated (a) using in vitro transcription assays and (b) by quantitative fluorometric assays and direct microscopic observation of probes bound to mRNA in its native form. These features render Glowing LNA as promising diagnostic probes for biomedical applications.

Component resolved bleaching study in natural calcium fluoride using CW-OSL, LM-OSL and residual TL glow curves after bleaching.

PubMed

Angeli, Vasiliki; Polymeris, George S; Sfampa, Ioanna K; Tsirliganis, Nestor C; Kitis, George

2017-04-01

Natural calcium fluoride has been commonly used as thermoluminescence (TL) dosimeter due to its high luminescence intensity. The aim of this work includes attempting a correlation between specific TL glow curves after bleaching and components of linearly modulated optically stimulated luminescence (LM-OSL) as well as continuous wave OSL (CW-OSL). A component resolved analysis was applied to both integrated intensity of the RTL glow curves and all OSL decay curves, by using a Computerized Glow-Curve De-convolution (CGCD) procedure. All CW-OSL and LM-OSL components are correlated to the decay components of the integrated RTL signal, apart from two RTL components which cannot be directly correlated with either LM-OSL or CW-OSL component. The unique, stringent criterion for this correlation deals with the value of the decay constant λ of each bleaching component. There is only one, unique bleaching component present in all three luminescence entities which were the subject of the present study, indicating that each TL trap yields at least three different bleaching components; different TL traps can indicate bleaching components with similar values. According to the data of the present work each RTL bleaching component receives electrons from at least two peaks. The results of the present study strongly suggest that the traps that contribute to TL and OSL are the same. Copyright © 2017 Elsevier Ltd. All rights reserved.

Time-delayed transition of normal-to-abnormal glow in pin-to-water discharge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yoon, S.-Y.; Byeon, Y.-S.; Yoo, S.

2016-08-15

Time-delayed transition of normal-to-abnormal glow was investigated in discharge between spoke-like pins and ultrapure water by applying AC-driven power at a frequency of 14.3 kHz at atmospheric pressure. The normal-to-abnormal transition can be recognized from the slope changes of current density, gas temperature, electrode temperature, and OH density. The slope changes took place in tens of minutes rather than just after discharge, in other words, the transition was delayed. The time-delay of the transition was caused by the interaction between the plasma and water. The plasma affected water properties, and then the water affected plasma properties.

Study on the characteristics of hysteresis loop and resistance of glow discharge plasma using argon gas

NASA Astrophysics Data System (ADS)

Mathew, Prijil; Sajith Mathews, T.; Kurian, P. J.; Chattopadyay, P. K.

2018-05-01

Hysteresis in discharge current is produced in a low-pressure, magnetic field free, Glow discharge plasma by varying discharge voltage. The variation in area of the hysteresis loops with pressure, electrode distance and load resistor studied. To understand, the nonlinear behaviour of the I-V characteristics, the changes in gas resistance with electrode voltage, pressure and load resistor were studied. After many trials we propose the best suitable empirical equation for the exponential decrease of the gas resistance with electrode voltage as; R = Rmin + Ae-0.008V, which is a novel one and matches well with our experimental results.

Experimental Simulation of the Interaction of Biased Solar Arrays with the Space Plasma

NASA Technical Reports Server (NTRS)

Kaufman, H. R.; Robinson, R. S.

1981-01-01

The phenomenon of unexpectedly large leakage currents collected by small exposed areas of high voltage solar arrays operating in a plasma environment was investigated. Polyimide (Kapton) was the insulating material used in all tests. Both positive bias (electron collection) and negative bias (ion collection) tests were performed. A mode change in the electron collection mechanism was associated with a glow discharge process and was found to be related to the neutral background density. Results indicate that the glow discharge collection mode does not occur in a space environment where the background density is considerably lower than that of the vacuum facility used.

True random bit generators based on current time series of contact glow discharge electrolysis

NASA Astrophysics Data System (ADS)

Rojas, Andrea Espinel; Allagui, Anis; Elwakil, Ahmed S.; Alawadhi, Hussain

2018-05-01

Random bit generators (RBGs) in today's digital information and communication systems employ a high rate physical entropy sources such as electronic, photonic, or thermal time series signals. However, the proper functioning of such physical systems is bound by specific constrains that make them in some cases weak and susceptible to external attacks. In this study, we show that the electrical current time series of contact glow discharge electrolysis, which is a dc voltage-powered micro-plasma in liquids, can be used for generating random bit sequences in a wide range of high dc voltages. The current signal is quantized into a binary stream by first using a simple moving average function which makes the distribution centered around zero, and then applying logical operations which enables the binarized data to pass all tests in industry-standard randomness test suite by the National Institute of Standard Technology. Furthermore, the robustness of this RBG against power supply attacks has been examined and verified.

Method of making a coating of a microtextured surface

DOEpatents

Affinito, John D [Tucson, AZ; Graff, Gordon L [West Richland, WA; Martin, Peter M [Kennewick, WA; Gross, Mark E [Pasco, WA; Burrows, Paul E [Kennewick, WA; Sapochak, Linda S [Henderson, NV

2004-11-02

A method for conformally coating a microtextured surface. The method includes flash evaporating a polymer precursor forming an evaporate, passing the evaporate to a glow discharge electrode creating a glow discharge polymer precursor plasma from the evaporate, cryocondensing the glow discharge polymer precursor plasma on the microtextured surface and crosslinking the glow discharge polymer precursor plasma thereon, wherein the crosslinking resulting from radicals created in the glow discharge polymer precursor plasma.

The improvement of the analytical performance of direct current atmospheric pressure glow discharge generated in contact with the small-sized liquid cathode after the addition of non-ionic surfactants to electrolyte solutions.

PubMed

Gręda, Krzysztof; Jamróz, Piotr; Pohl, Paweł

2013-04-15

A low power direct current atmospheric glow discharge sustained in the open to air atmosphere in contact with a small-sized flowing liquid cathode was used as an excitation source in optical emission spectrometry. The composition of electrolyte solutions served as the liquid cathode was modified by the addition of non-ionic surfactants, namely Triton x-45, Triton x-100, Triton x-405 and Triton x-705. The effect of the concentration of each surfactant was thoroughly studied on the emission characteristic of molecular bands identified in spectra, atomic emission lines of 16 metals studied and the background level. It was found that the presence of both heavy surfactants results in a significant increase in the net intensity of analytical lines of metals and a notable reduction of the intensity of bands of diatomic molecules and the background. In conditions considered to be a compromise for all metals, selected figures of merit for this excitation source combined with the optical emission spectrometry detection were determined. Limits of detection for all metals were within the range of 0.0003-0.05 mg L(-1), the precision was better than 6%, while calibration curves were linear over 2 orders of the magnitude of the concentration or more, e.g., for K, Li, Mg, Na and Rb. The discharge system with the liquid cathode modified by the addition of the surfactant found its application in the determination of Ca, Cu, Fe, K, Mg, Mn, Na and Zn in selected environmental samples, i.e., waters, soils and spruce needles, with the quite good precision and the accuracy comparable to that for measurements with flame atomic absorption spectrometry (FAAS) and flame atomic emission spectrometry (FAES). Copyright © 2013 Elsevier B.V. All rights reserved.

A ground-based experimental test program to duplicate and study the spacecraft glow phenomenon

NASA Technical Reports Server (NTRS)

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

1985-01-01

The use of a plasma device, the Advanced Concepts Torus-I, for producing atoms and molecules to study spacecraft glow mechanisms is discussed. A biased metal plate, located in the plasma edge, is used to accelerate and neutralize plasma ions, thus generating a neutral beam with a flux approx. 5 x 10 to the 14th power/sq cm/sec at the end of a drift tube. Our initial experiments are to produce a 10 eV molecular and atomic nitrogen beam directed onto material targets. Photon emission in the spectral range 2000 to 9000 A from excited species formed on the target surface will be investigated.

From hot rocks to glowing avalanches: Numerical modelling of gravity-induced pyroclastic density currents and hazard maps at the Stromboli volcano (Italy)

NASA Astrophysics Data System (ADS)

Salvatici, Teresa; Di Roberto, Alessio; Di Traglia, Federico; Bisson, Marina; Morelli, Stefano; Fidolini, Francesco; Bertagnini, Antonella; Pompilio, Massimo; Hungr, Oldrich; Casagli, Nicola

2016-11-01

Gravity-induced pyroclastic density currents (PDCs) can be produced by the collapse of volcanic crater rims or due to the gravitational instability of materials deposited in proximal areas during explosive activity. These types of PDCs, which are also known as ;glowing avalanches;, have been directly observed, and their deposits have been widely identified on the flanks of several volcanoes that are fed by mafic to intermediate magmas. In this research, the suitability of landslide numerical models for simulating gravity-induced PDCs to provide hazard assessments was tested. This work also presents the results of a back-analysis of three events that occurred in 1906, 1930 and 1944 at the Stromboli volcano by applying a depth-averaged 3D numerical code named DAN-3D. The model assumes a frictional internal rheology and a variable basal rheology (i.e., frictional, Voellmy and plastic). The numerical modelling was able to reproduce the gravity-induced PDCs' extension and deposit thicknesses to an order of magnitude of that reported in the literature. The best results when compared with field data were obtained using a Voellmy model with a frictional coefficient of f = 0.19 and a turbulence parameter ξ = 1000 m s- 1. The results highlight the suitability of this numerical code, which is generally used for landslides, to reproduce the destructive potential of these events in volcanic environments and to obtain information on hazards connected with explosive-related, mass-wasting phenomena in Stromboli Island and at volcanic systems characterized by similar phenomena.

Cathode fall model and current-voltage characteristics of field emission driven direct current microplasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Venkattraman, Ayyaswamy

2013-11-15

The post-breakdown characteristics of field emission driven microplasma are studied theoretically and numerically. A cathode fall model assuming a linearly varying electric field is used to obtain equations governing the operation of steady state field emission driven microplasmas. The results obtained from the model by solving these equations are compared with particle-in-cell with Monte Carlo collisions simulation results for parameters including the plasma potential, cathode fall thickness, ion number density in the cathode fall, and current density vs voltage curves. The model shows good overall agreement with the simulations but results in slightly overpredicted values for the plasma potential andmore » the cathode fall thickness attributed to the assumed electric field profile. The current density vs voltage curves obtained show an arc region characterized by negative slope as well as an abnormal glow discharge characterized by a positive slope in gaps as small as 10 μm operating at atmospheric pressure. The model also retrieves the traditional macroscale current vs voltage theory in the absence of field emission.« less

Dynamic Contraction of the Positive Column of a Self-Sustained Glow Discharge in Molecular Gas Flow

NASA Astrophysics Data System (ADS)

Shneider, Mikhail

2014-10-01

Contraction of the gas discharge, when current contracts from a significant volume of weakly ionized plasma into a thin arc channel, was attracted attention of scientists for more than a century. Studies of the contraction (also called constriction) mechanisms, besides carrying interesting science, are of practical importance, especially when contraction should be prevented. A set of time-dependent two-dimensional equations for the non-equilibrium weakly-ionized nitrogen/ air plasma is formulated. The process is described by a set of time-dependent continuity equations for the electrons, positive and negative ions; gas and vibrational temperature; by taking into account the convective heat and plasma losses by the transverse flux. Transition from the uniform to contracted state was analyzed. It was shown that such transition experiences a hysteresis, and that the critical current of the transition increases when the pressure (gas density) drops. Possible coexistence of the contracted and uniform state of the plasma in the discharge where the current flows along the density gradient of the background gas was discussed. In this talk the problems related to the dynamic contraction of the current channel inside a quasineutral positive column of a self-sustained glow discharge in molecular gas in a rectangular duct with convection cooling will be discussed. Study presented in this talk was stimulated by the fact that there are large number of experiments on the dynamic contraction of a glow discharge in nitrogen and air flows and a many of possible applications. Similar processes play a role in the powerful gas-discharge lasers. In addition, the problem of dynamic contraction in the large volume of non-equilibrium weakly ionized plasma is closely related to the problem of streamer to leader transitions in lightning and blue jets.

VISUAL ALARM SYSTEM

DOEpatents

Morris, J.M.

1958-11-01

A vlsual alarm system, particularly a system incorporating a gas-fllled diode glow bulb, for indicating a minor alarm and also a major alarm is presented. In operation, the disclosed system responds to a signal indlcative of a caution condition by applying a d-c voltage across the glow bulb to induce a glow at one electrode. If a signal indicative of a critlcal condition is received, the system applies an a-c voltage across tbe glow bulb to produce a glow discharge at each electrode.

Electron energy distribution function in the positive column of a neon glow discharge using the black wall approximation

NASA Astrophysics Data System (ADS)

Al-Hawat, Sh; Naddaf, M.

2005-04-01

The electron energy distribution function (EEDF) was determined from the second derivative of the I-V Langmuir probe characteristics and, thereafter, theoretically calculated by solving the plasma kinetic equation, using the black wall (BW) approximation, in the positive column of a neon glow discharge. The pressure has been varied from 0.5 to 4 Torr and the current from 10 to 30 mA. The measured electron temperature, density and electric field strength were used as input data for solving the kinetic equation. Comparisons were made between the EEDFs obtained from experiment, the BW approach, the Maxwellian distribution and the Rutcher solution of the kinetic equation in the elastic energy range. The best conditions for the BW approach are found to be under the discharge conditions: current density jd = 4.45 mA cm-2 and normalized electric field strength E/p = 1.88 V cm-1 Torr-1.

Dynamic contraction of the positive column of a self-sustained glow discharge in air flow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shneider, M. N.; Mokrov, M. S.; Milikh, G. M.

We study the dynamic contraction of a self-sustained glow discharge in air in a rectangular duct with convective cooling. A two dimensional numerical model of the plasma contraction was developed in a cylindrical frame. The process is described by a set of time-dependent continuity equations for the electrons, positive and negative ions; gas and vibrational temperature; and equations which account for the convective heat and plasma losses by the transverse flux. Transition from the uniform to contracted state was analyzed. It was shown that such transition experiences a hysteresis, and that the critical current of the transition increases when themore » gas density drops. Possible coexistence of the contracted and uniform state of the plasma in the discharge, where the current flows along the density gradient of the background gas, is discussed.« less

Thermoluminescence characteristics of a chondrite (Holbrook) and an aubrite achondrite (Norton County) meteorites.

PubMed

Bossin, Lily; Kazakis, Nikolaos A; Kitis, George; Tsirliganis, Nestor C

2017-09-01

The present study constitutes the first part of a meteorite project, currently in progress, towards the full and thorough dosimetric study (TL and OSL) of two different meteorites of recent fall, Norton County and Holbrook. Both meteorites exhibit strong TL sensitivity, linear dose response and no saturation for doses up to 2kGy. However, the two meteorites exhibited a very dissimilar TL glow curve and behaviour regarding sensitization and fading. Notably, the Norton County aubrite achondrite was found to exhibit a strong fading of the high-temperature peak (~300°C), attributed to anomalous fading, whereas Holbrook did not seem to show signs of anomalous fading. Since quantitative conclusions regarding the thermal and irradiation history of meteorites, require knowledge of the detailed peak structure of the glow curve and deeper understanding of the trapping mechanism, the glow curves, after irradiation in the range 10-2000Gy, were deconvoluted using general order kinetics. The fitting parameters extracted point towards complex non-strictly first order mechanisms with a multitude of traps acting very differently. All the above, combined with future OSL measurements, currently in progress, are expected to shed light on the nature of the involved traps in both phenomena (energy depth, light-resistance etc), which would allow to extract more concrete conclusions about their history. Copyright © 2017 Elsevier Ltd. All rights reserved.

Applicability of the Child-Langmuir laws versions for describing the glow discharge cathode sheath in CO2

NASA Astrophysics Data System (ADS)

Lisovskiy, Valeriy; Krol, Hennadii; Osmayev, Ruslan; Yegorenkov, Vladimir

2016-09-01

This work is devoted to the determination of the law that may be applicable to the description of the cathode sheath in CO2. To this end three versions of the Child-Langmuir law have been considered - a collision free one (for the ions moving through a cathode sheath without collisions with gas molecules) as well as two collision- related versions- one for a constant mean free path of positive ions and one for a constant mobility of positive ions. The current-voltage characteristics and the cathode sheath thickness of the glow discharge in carbon oxide have been simultaneously measured in the pressure range from 0.05 to 1 Torr and with the discharge current values up to 80 mA. The inter-electrode distance has been chosen such that the discharge consists only of the cathode sheath and a small portion of the negative glow, i.e. the experiments have been performed in short tubes. In this case the voltage drop across the cathode sheath is equal approximately to the voltage drop across the electrodes. In the whole range of the discharge conditions we have studied the cathode sheath characteristics are found to obey correctly only to the Child-Langmuir law version with a constant ion mobility. The reason for this phenomenon may be related with a significant conversion of carbon dioxide molecules.

Cathode fall thickness of abnormal glow discharges between parallel-plane electrodes in different radii at low pressure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fu, Yangyang; Luo, Haiyun; Zou, Xiaobing

2015-02-15

In order to investigate the influence of electrode radius on the characteristics of cathode fall thickness, experiments of low-pressure (20 Pa ≤ p ≤ 30 Pa) abnormal glow discharge were carried out between parallel-plane electrodes in different radii keeping gap distance unchanged. Axial distributions of light intensity were obtained from the discharge images captured using a Charge Coupled Device camera. The assumption that the position of the negative glow peak coincides with the edge of cathode fall layer was verified based on a two-dimensional model, and the cathode fall thicknesses, d{sub c}, were calculated from the axial distributions of light intensity. It was observedmore » that the position of peak emission shifts closer to the cathode as current or pressure grows. The dependence of cathode fall thickness on the gas pressure and normalized current J/p{sup 2} was presented, and it was found that for discharges between electrodes in large radius the curves of pd{sub c} against J/p{sup 2} were superimposed on each other, however, this phenomenon will not hold for discharges between the smaller electrodes. The reason for this phenomenon is that the transverse diffusions of charged particles are not the same in two gaps between electrodes with different radii.« less

Full spatial-field visualization of gas temperature in an air micro-glow discharge by calibrated Schlieren photography

NASA Astrophysics Data System (ADS)

Xiong, Qing; Xu, Le; Wang, Xia; Xiong, Lin; Huang, Qinghua; Chen, Qiang; Wang, Jingang; Peng, Wenxiong; Li, Jiarui

2018-03-01

Gas temperature is an important basic parameter for both fundamental research and applications of plasmas. In this work, efforts were made to visualize the full spatial field of gas temperature (T g) in a microdischarge with sharp T g gradients by a method of calibrated Schlieren (CS) photography. Compared to other two typical diagnostic approaches, optical emission spectroscopy (OES) and Rayleigh scattering, the proposed CS method exhibits the ability to capture the whole field of gas temperature using a single Schlieren image, even the discharge is of non-luminous zones like Faraday dark space (FDS). The image shows that the T g field in the studied micro-glow air discharge expands quickly with the increase of discharge currents, especially in the cathode region. The two-dimensional maps of gas temperature display a ‘W-shape’ with sharp gradients in both areas of negative and positive glows, slightly arched distributions in the positive column, and cooling zones in the FDS. The obtained T g fields show similar patterns to that of the discharge luminance. With an increase in discharge currents, more electric energy is dissipated by heating air gas and inducing constriction of the low-temperature FDS. Except in the vicinities of electrode boundaries, due to the interference from optical diffraction, the estimated gas temperature distributions are of acceptable accuracy, confirmed by the approaches of OES and UV Rayleigh scattering.

Model Insensitive and Calibration Independent Method for Determination of the Downstream Neutral Hydrogen Density Through Ly-alpha Glow Observations

NASA Technical Reports Server (NTRS)

Gangopadhyay, P.; Judge, D. L.

1996-01-01

Our knowledge of the various heliospheric phenomena (location of the solar wind termination shock, heliopause configuration and very local interstellar medium parameters) is limited by uncertainties in the available heliospheric plasma models and by calibration uncertainties in the observing instruments. There is, thus, a strong motivation to develop model insensitive and calibration independent methods to reduce the uncertainties in the relevant heliospheric parameters. We have developed such a method to constrain the downstream neutral hydrogen density inside the heliospheric tail. In our approach we have taken advantage of the relative insensitivity of the downstream neutral hydrogen density profile to the specific plasma model adopted. We have also used the fact that the presence of an asymmetric neutral hydrogen cavity surrounding the sun, characteristic of all neutral densities models, results in a higher multiple scattering contribution to the observed glow in the downstream region than in the upstream region. This allows us to approximate the actual density profile with one which is spatially uniform for the purpose of calculating the downstream backscattered glow. Using different spatially constant density profiles, radiative transfer calculations are performed, and the radial dependence of the predicted glow is compared with the observed I/R dependence of Pioneer 10 UV data. Such a comparison bounds the large distance heliospheric neutral hydrogen density in the downstream direction to a value between 0.05 and 0.1/cc.

Glow Sticks: Spectra and Color Mixing

NASA Astrophysics Data System (ADS)

Birriel, Jennifer; Birriel, Ignacio

2014-10-01

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.1-3 A black light can be used to illuminate glow sticks that have not been cracked or those that are "dead" in order to demonstrate fluorescence in liquid chemicals.4 In this article, we present the use of glow sticks as an inexpensive demonstration of spectra and color addition.

Up-conversion of MMW radiation to visual band using glow discharge detector and silicon detector

NASA Astrophysics Data System (ADS)

Aharon Akram, Avihai; Rozban, Daniel; Abramovich, Amir; Yitzhaky, Yitzhak; Kopeika, Natan S.

2016-10-01

In this work we describe and demonstrate a method for up-conversion of millimeter wave (MMW) radiation to the visual band using a very inexpensive miniature Glow Discharge Detector (GDD), and a silicon detector (photodetector). Here we present 100 GHz up-conversion images based on measuring the visual light emitting from the GDD rather than its electrical current. The results showed better response time of 480 ns and better sensitivity compared to the electronic detection that was performed in our previous work. In this work we performed MMW imaging based on this method using a GDD lamp, and a photodetector to measure GDD light emission.

Dynamic model based on voltage transfer curve for pattern formation in dielectric barrier glow discharge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Ben; He, Feng; Ouyang, Jiting, E-mail: jtouyang@bit.edu.cn

2015-12-15

Simulation work is very important for understanding the formation of self-organized discharge patterns. Previous works have witnessed different models derived from other systems for simulation of discharge pattern, but most of these models are complicated and time-consuming. In this paper, we introduce a convenient phenomenological dynamic model based on the basic dynamic process of glow discharge and the voltage transfer curve (VTC) to study the dielectric barrier glow discharge (DBGD) pattern. VTC is an important characteristic of DBGD, which plots the change of wall voltage after a discharge as a function of the initial total gap voltage. In the modeling,more » the combined effect of the discharge conditions is included in VTC, and the activation-inhibition effect is expressed by a spatial interaction term. Besides, the model reduces the dimensionality of the system by just considering the integration effect of current flow. All these greatly facilitate the construction of this model. Numerical simulations turn out to be in good accordance with our previous fluid modeling and experimental result.« less

Optimisation of the readout parameters when evaluating thermal neutron doses by TL dosimetry with LiF:Mg,Ti.

PubMed

German, U; Weinstein, M; Abraham, A; Alfassi, Z B

2007-01-01

The location of the glow peaks depends on the heating rate. It takes some time until the crystal reaches the heater temperature, and this time lag has a direct effect on the shift of peaks towards higher temperatures. Some information on the high-temperature peaks may be lost if the readout conditions (mainly length of time) are not properly chosen. Step heating profiles to a varying final temperature between 300 degrees C and 125 degrees C were used to study the time dependence of the collected information in the glow curves of (6)LiF:Mg,Ti crystals, and the minimal heating time for evaluation of thermal neutron doses was determined.

Optical glow spectra arising from low-energy N2, N2(+) and electron bombardment of MgF2 surfaces

NASA Technical Reports Server (NTRS)

Qi, J.; Barnes, A. V.; Espy, S. L.; Riehl-Chudoba, M.; Sun, C.-N.; Albridge, R. G.; Tolk, N. H.

1991-01-01

Photon emission spectra resulting from the impact of N2, N2(+), and electron beams on magnesium fluoride in an ultrahigh vacuum environment were measured and compared for beam energies in the range 200-2000 eV. Unexpectedly, only the ion- and electron-induced spectra exhibited broad fluorescence. The observed data suggest that the broad fluorescence arising from low-energy ion bombardment is due primarily to the transfer of electronic energy to the surface by resonance or Auger neutralization. Since molecular nitrogen is a major constituent of the atmosphere at orbital altitudes, these measurements bear directly on radiation-induced glow and erosion processes on surfaces of spacecraft in low-earth orbit.

Thermoluminscence of irradiated herbs and spices

NASA Astrophysics Data System (ADS)

Mamoon, A.; Abdul-Fattah, A. A.; Abulfaraj, W. H.

1994-07-01

Several types of herbs and spices from the local market were irradiated with different doses of γ radiations. Doses varied from a few kilograys to 10 kilograys. Thermoluminescence of the irradiated samples and their controls was investigated. For the same type of herb or spice glow curves of different magnitudes, corresponding somewhat to the doses given, were obtained from the irradiated samples. Most control samples gave little or insignificant glow. Glow curves from different herbs and spices irradiated with the same doses were not similar in the strength of the glow signal given. Samples of the black pepper obtained from different packages sometimes give glow curves of very different intensities. Samples from irradiated black pepper were found to show little fading of their glow curves even at 9 months postirradiation. All irradiations were done under the same experimental conditions and at a dose rate of approximately 1 kGy h-1. The glow curves were obtained using a heating rate of about 9°C s-1 and a constant nitrogen flow rate.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choudhary, Mangilal, E-mail: mangilal@ipr.res.in; Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400085; Mukherjee, S.

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

Effect of turbulent flow on an atmospheric-pressure AC powered gliding arc discharge

NASA Astrophysics Data System (ADS)

Kong, Chengdong; Gao, Jinlong; Zhu, Jiajian; Ehn, Andreas; Aldén, Marcus; Li, Zhongshan

2018-06-01

A high-power gliding arc (GA) discharge was generated in a turbulent air flow driven by a 35 kHz alternating current electric power supply. The effects of the flow rate on the characteristics of the GA discharge were investigated using combined optical and electrical diagnostics. Phenomenologically, the GA discharge exhibits two types of discharge, i.e., glow type and spark type, depending on the flow rates and input powers. The glow-type discharge, which has peak currents of hundreds of milliamperes, is sustained at low flow rates. The spark-type discharge, which is characterized by a sharp current spike of several amperes with duration of less than 1 μs, occurs more frequently as the flow rate increases. Higher input power can suppress spark-type discharges in moderate turbulence, but this effect becomes weak under high turbulent conditions. Physically, the transition between glow- and spark-type is initiated by the short cutting events and the local re-ignition events. Short cutting events occur owing to the twisting, wrinkling, and stretching of the plasma columns that are governed by the relatively large vortexes in the flow. Local re-ignition events, which are defined as re-ignition along plasma columns, are detected in strong turbulence due to increment of the impedance of the plasma column and consequently the internal electric field strength. It is suggested that the vortexes with length scales smaller than the size of the plasma can penetrate into the plasma column and promote mixing with surroundings to accelerate the energy dissipation. Therefore, the turbulent flow influences the GA discharges by ruling the short cutting events with relatively large vortexes and the local re-ignition events with small vortexes.

Generation of large-area and glow-like surface discharge in atmospheric pressure air

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Ying; Bi, Zhenhua; Wang, Xueyang

2016-08-15

A large-area (6 cm × 6 cm) air surface dielectric barrier discharge has been generated at atmospheric pressure by using well-aligned and micron-sized dielectric tubes with tungsten wire electrodes. Intensified CCD images with an exposure time of 5 ns show that the uniform surface air discharge can be generated during the rising and falling time of pulsed DC voltage. Current and voltage and optical measurements confirm the formation of glow-like air discharges on the surface of micron-sized dielectric tubes. Simulation results indicate that the microelectrode configuration contributes to the formation of strong surface electric field and plays an important role in the generation of uniformmore » surface air discharge.« less

The Electrostatic Environments of Mars: Atmospheric Discharges

NASA Technical Reports Server (NTRS)

Calle, Carlos I.; Mackey, Paul J.; Johansen, Michael R.; Hogue, Michael D.; Phillips, James, III; Cox, Rachel E.

2016-01-01

The electrostatic environment on Mars is controlled by its ever present atmospheric dust. Dust devils and dust storms tribocharge this dust. Theoretical studies predict that lightning and/or glow discharges should be present on Mars, but none have been directly observed. Experiments are planned to shed light on this issue.

Relativistic electron avalanches as a thunderstorm discharge competing with lightning

NASA Astrophysics Data System (ADS)

Kelley, Nicole A.; Smith, David M.; Dwyer, Joseph R.; Splitt, Michael; Lazarus, Steven; Martinez-McKinney, Forest; Hazelton, Bryna; Grefenstette, Brian; Lowell, Alexander; Rassoul, Hamid K.

2015-08-01

Gamma-ray `glows' are long duration (seconds to tens of minutes) X-ray and gamma-ray emission coming from thunderclouds. Measurements suggest the presence of relativistic runaway electron avalanches (RREA), the same process underlying terrestrial gamma-ray flashes. Here we demonstrate that glows are relatively a common phenomena near the tops of thunderstorms, when compared with events such as terrestrial gamma-ray flashes. Examining the strongest glow measured by the airborne detector for energetic emissions, we show that this glow is measured near the end of a downward RREA, consistent with occurring between the upper positive charge layer and the negative screening layer above it. The glow discharges the upper positive layer by >=9.6 mA, strong enough to be an important charging mechanism of the storm. For this glow, the gamma-ray flux observed is close to the value at which relativistic feedback processes become important, with an avalanche multiplication factor of 4,500.

Aspects of the practical application of titanium alloys after low temperature nitriding glow discharge in hydrogen- free -gas media

NASA Astrophysics Data System (ADS)

Mashovets, N. S.; Pastukh, I. M.; Voloshko, S. M.

2017-01-01

X-ray diffraction analysis, X-ray photoelectron spectroscopy, and Electron Auger-spectroscopy investigation of phase transformation on the surface of the VT8 titanium alloy after a low temperature hydrogen-free nitriding in a glow discharge. Operational characteristics of titanium alloys defined physical-mechanical characteristics of the surface and their phase composition, which depend on the process parameters of nitriding. Surface modification of titanium alloys were carried out by low-temperature nitriding in a glow discharge in hydrogen-free environment. The main advantage of this method lies in the absence of hydrogen embrittlement and complete environmental safety process. Application of the glow discharge can not only speed up the process by the order of the diffusion surface saturation with nitrogen, but also significantly alters the kinetics of the process and quality of the nitrided layer, in particular its physio-mechanical properties and phase composition. For research purposes, the standards from an α + β alloy Ti-Al6-Cr2-Mo2,5 (VT8) were used. Research into the phase composition was performed by X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). Stratified analysis by AES was conducted by etching the surface of the samples' argon ion beam with diameters of 1.5 mm with an energy of 3000 eV and a current density of 400 mA/cm2. The above material shows the promise of the technology of low-temperature hydrogen-nitriding by glow discharge. This greatly expands the range of practical applications of titanium alloys. In addition, changing the technological mode allows you to manage a wide range of modified phase composition of the surface layer and as a result - to form the surface of titanium parts, taking into account the conditions of the subsequent operation.

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.

Thermoluminescence glow curve analysis and CGCD method for erbium doped CaZrO{sub 3} phosphor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tiwari, Ratnesh, E-mail: 31rati@gmail.com; Chopra, Seema

2016-05-06

The manuscript report the synthesis, thermoluminescence study at fixed concentration of Er{sup 3+} (1 mol%) doped CaZrO{sub 3} phosphor. The phosphors were prepared by modified solid state reaction method. The powder sample was characterized by thermoluminescence (TL) glow curve analysis. In TL glow curve the optimized concentration in 1mol% for UV irradiated sample. The kinetic parameters were calculated by computerized glow curve deconvolution (CGCD) techniaue. Trapping parameters gives the information of dosimetry loss in prepared phosphor and its usability in environmental monitoring and for personal monitoring. CGCD is the advance tool for analysis of complicated TL glow curves.

Means of introducing an analyte into liquid sampling atmospheric pressure glow discharge

DOEpatents

Marcus, R. Kenneth; Quarles, Jr., Charles Derrick; Russo, Richard E.; Koppenaal, David W.; Barinaga, Charles J.; Carado, Anthony J.

2017-01-03

A liquid sampling, atmospheric pressure, glow discharge (LS-APGD) device as well as systems that incorporate the device and methods for using the device and systems are described. The LS-APGD includes a hollow capillary for delivering an electrolyte solution to a glow discharge space. The device also includes a counter electrode in the form of a second hollow capillary that can deliver the analyte into the glow discharge space. A voltage across the electrolyte solution and the counter electrode creates the microplasma within the glow discharge space that interacts with the analyte to move it to a higher energy state (vaporization, excitation, and/or ionization of the analyte).

Laser Initiation of PETN containing Nickel Inclusions

NASA Astrophysics Data System (ADS)

Aduev, B. P.; Zvekov, A. A.; Nurmukhametov, D. R.; Nikitin, A. P.

2017-01-01

The spectral and kinetic characteristics of pentaerythritol tetranitrate (PETN) containing nickel nanoparticles glow initiated by laser pulses was studied with high temporal resolution. It was shown that glow which is chemiluminescence arises as a result of chemical reaction initiation. We suggest that the glow is concerned on excited nitrogen dioxide NO2 luminescence. The reaction propagation leads to the explosion in the microsecond time range that is accompanied by thermal glow of the reaction products with temperature T=4300 K.

Space vehicle glow measurements on STS 41-D

NASA Technical Reports Server (NTRS)

Mende, S. B.; Swenson, G. R.; Clifton, K. S.; Gause, R.; Leger, L.; Garriott, O. K.

1985-01-01

A flight experiment using a hand-held, image-intensified spectrographic camera was performed on mission 41-D. The instrument enabled the photographic documentation of the position of the spectral slit on the image to be subjected to spectrographic analysis. Because of this instrument feature, the spectrum of the glow on the Shuttle tail pod could be clearly separated from spectrum of the scattered light from the Orbiter. From the measurements it is clear that the spectrum of the glow is a continuum in the passband of the instrument between 4200 A and 8000 A. The measured spectral resolution of the instrument was 35 A. The scattered light from the Orbiter surfaces distinctly show the components of the earth's airglow at 5577 A and 7620 A. On the same flight material samples were also carried by the Orbiter attached to the Remote Manipulating System arm. These samples were representative of the material overcoatings used on the space telescope. The altitude of the 41-D flight was 290 km, instead of the 220 km which was originally planned for this experiment. The signal to noise ratio in the material glow discrimination experiment was quite low. This made it difficult to draw strong conclusions regarding the glow propensity of the materials. Nevertheless it was clear that polyethylene produces a very weak glow, while most black overcoating materials produce significant glow. MgF2 was also found to produce a relatively intense glow.

Specific features of a single-pulse sliding discharge in neon near the threshold for spark breakdown

NASA Astrophysics Data System (ADS)

Trusov, K. K.

2017-08-01

Experimental data on the spatial structure of a single-pulse sliding discharge in neon at voltages below, equal to, and above the threshold for spark breakdown are discussed. The experiments were carried at gas pressures of 30 and 100 kPa and different polarities of the discharge voltage. Photographs of the plasma structure in two discharge chambers with different dimensions of the discharge zone and different thicknesses of an alumina dielectric plate on the surface of which the discharge develops are inspected. Common features of the prebreakdown discharge and its specific features depending on the voltage polarity and gas pressure are analyzed. It is shown that, at voltages below the threshold for spark breakdown, a low-current glow discharge with cathode and anode spots develops in the electrode gap. Above the breakdown threshold, regardless of the voltage polarity, spark channels directed from the cathode to the anode develop against the background of a low-current discharge.

Dirty Bombs: The Technical Aspects of Radiological Dispersion Devices

DTIC Science & Technology

2004-06-01

people such as a business district, subway station, or entertainment district. By striking one of these targets not only would many people be directly...the resulting 35 appearance. One six-year-old girl “rubbed the powder on her body so that she glowed and sparkled” and later ate a sandwich with

Comment on ``heating rate effects in thermoluminescent glow-peaks''

NASA Astrophysics Data System (ADS)

Horowitz, Y.

1993-12-01

In a recent article, Kitis et al. [Nucl. Instr. and Meth. B 73 (1993) 367] discuss the effect of heating rate on three well-known thermoluminescence (TL) glow peaks; the 110°C glow peak of Norwegian quartz, the 210°C "dosimetry" glow peak of LiF:Mg,Ti (peak 5 in TLD-700) and the 250°C glow peak of natural Cap 2 : MBLE. The authors state that they focus their attention on "single, well-separated, glow peaks" in order to "test the theory", presumably charge detrapping kinetic theory. To achieve this rather elusive goal for the 210°C peak in LiF:Mg,Ti, the authors employ a 140°C/60 min post-irradiation anneal to depopulate the low temperature peaks. There is, however, substantial evidence in the TL literature over the past three decades that an anneal of this duration at elevated temperatures induces various thermally activated clustering and precipitation processes leading to trap modification and possible creation of new traps.

Direct coupling of pulsed radio frequency and pulsed high power in novel pulsed power system for plasma immersion ion implantation.

PubMed

Gong, Chunzhi; Tian, Xiubo; Yang, Shiqin; Fu, Ricky K Y; Chu, Paul K

2008-04-01

A novel power supply system that directly couples pulsed high voltage (HV) pulses and pulsed 13.56 MHz radio frequency (rf) has been developed for plasma processes. In this system, the sample holder is connected to both the rf generator and HV modulator. The coupling circuit in the hybrid system is composed of individual matching units, low pass filters, and voltage clamping units. This ensures the safe operation of the rf system even when the HV is on. The PSPICE software is utilized to optimize the design of circuits. The system can be operated in two modes. The pulsed rf discharge may serve as either the seed plasma source for glow discharge or high-density plasma source for plasma immersion ion implantation (PIII). The pulsed high-voltage glow discharge is induced when a rf pulse with a short duration or a larger time interval between the rf and HV pulses is used. Conventional PIII can also be achieved. Experiments conducted on the new system confirm steady and safe operation.

Non-radiation induced signals in TL dosimetry.

PubMed

German, U; Weinstein, M

2002-01-01

One source of background signals, which are non-radiation related, is the reader system and it includes dark current, external contaminants and electronic spikes. These factors can induce signals equivalent to several hundredths of mSv. Mostly, the effects are minimised by proper design of the TLD reader, but some effects are dependent on proper operation of the system. The other main group of background signals originates in the TL crystal and is due to tribothermoluminescence, dirt, chemical reactions and stimulation by visible or UV light. These factors can have a significant contribution, equivalent to over several mSv, depending on whether the crystal is bare or protected by PTFE. Working in clean environments, monitoring continuously the glow curves and performing glow curve deconvolution are suggested to minimise non-radiation induced spurious signals.

Determination of the plasma impedance of a glow discharge in carbon dioxide

NASA Astrophysics Data System (ADS)

Kiselev, A. S.; Smirnov, E. A.

2017-07-01

In this work an expression for the dynamic resistance of a glow discharge flowing in long tubes is obtained and analyzed. The expression describes the physical processes occurring in the positive column of a glow discharge. The frequency dependences of the active and reactive components as well as the dynamic resistance module for the discharge conditions corresponding to CO2-lasers have been calculated. Based on the simulation results developed a computer program in the C# programming language for modeling the dynamic resistance discharge of glow discharge lasers.

TL and OSL properties of beta irradiated Y2O3 nanocrystal

NASA Astrophysics Data System (ADS)

Shivaramu, N. J.; Lakshminarasappa, B. N.; Nagabhushana, K. R.; Tatumi, S. H.; Rocca, R. R.; Singh, Fouran

2017-05-01

Nanocrystalline yttrium oxide (Y2O3) is synthesized by low temperature sol-gel technique and synthesized material is annealed at 900°C. The annealed β-rayed Y2O3 two TL glows with prominent peak at 407 K and weak glow peak at 643 K were observed in all irradiated samples. It is found that TL glow peaks intensity linearly increases with increase in β-dose from 0.813 - 40.625 Gy. The TL kinetic parameters are calculated using glow curve deconvoluted (GCD) method. The TL glows exhibits general order kinetics. Intense optical stimulated luminescence (OSL) is observed in the Y2O3 sample. These material exhibits linearity and reproducibility and hence, it suggests that this material may be used as dosimetric applications.

In situ glow discharge plasma electrolytic synthesis of reduced TiO2 for enhanced visible light photocatalysis

NASA Astrophysics Data System (ADS)

Feng, Guang; Wu, Botao; Qayyum Khan, Abdul; Zeng, Heping

2018-05-01

Reduced titanium dioxide (TiO2‑x) due to its extraordinary visible light absorption has been widely investigated in photodegradation and water splitting nowadays. However, conventional routes to synthesize reduced TiO2 usually demand multiple preparation steps, harsh controlled conditions or expensive facilities. Here we developed a single-step in situ approach to prepare the gray TiO2‑x nanoparticles (sub-10 nm) effectively by the glow discharge plasma electrolysis (GDPE) under atmospheric pressure. The co-existence of self-doped oxygen vacancies and Ti3+ in the generated TiO2‑x nanoparticles is demonstrated by electron paramagnetic resonance (EPR). The tunable ratio of bulk/surface defect can be realized by controlling the glow discharge power directly. It should be noticed that Ti3+ in the synthesized TiO2‑x are quite stable in ambient air. The UV–vis spectra of gray TiO2‑x show an enhanced visible light absorption, which leads to high visible-light photocatalytic activity. Moreover, the as-prepared TiO2‑x after 6 months storage still shows excellent stability during photocatalytic reactions. Owing to its simplicity and effectivity, this preparation method with GDPE should provide a large-scale production for TiO2‑x with high photoactivity.

Atmospheric-pressure ionization and fragmentation of peptides by solution-cathode glow discharge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schwartz, Andrew J.; Shelley, Jacob T.; Walton, Courtney L.

Modern “-omics” (e.g., proteomics, glycomics, metabolomics, etc.) analyses rely heavily on electrospray ionization and tandem mass spectrometry to determine the structural identity of target species. Unfortunately, these methods are limited to specialized mass spectrometry instrumentation. Here in this paper, a novel approach is described that enables ionization and controlled, tunable fragmentation of peptides at atmospheric pressure. In the new source, a direct-current plasma is sustained between a tapered metal rod and a flowing sample-containing solution. As the liquid stream contacts the electrical discharge, peptides from the solution are volatilized, ionized, and fragmented. At high discharge currents (e.g., 70 mA), electrospray-likemore » spectra are observed, dominated by singly and doubly protonated molecular ions. At lower currents (35 mA), many peptides exhibit extensive fragmentation, with a-, b-, c-, x-, and y-type ion series present as well as complex fragments, such as d-type ions, not previously observed with atmospheric-pressure dissociation. Though the mechanism of fragmentation is currently unclear, observations indicate it could result from the interaction of peptides with gas-phase radicals or ultraviolet radiation generated within the plasma.« less

Atmospheric-pressure ionization and fragmentation of peptides by solution-cathode glow discharge

DOE PAGES

Schwartz, Andrew J.; Shelley, Jacob T.; Walton, Courtney L.; ...

2016-06-27

Modern “-omics” (e.g., proteomics, glycomics, metabolomics, etc.) analyses rely heavily on electrospray ionization and tandem mass spectrometry to determine the structural identity of target species. Unfortunately, these methods are limited to specialized mass spectrometry instrumentation. Here in this paper, a novel approach is described that enables ionization and controlled, tunable fragmentation of peptides at atmospheric pressure. In the new source, a direct-current plasma is sustained between a tapered metal rod and a flowing sample-containing solution. As the liquid stream contacts the electrical discharge, peptides from the solution are volatilized, ionized, and fragmented. At high discharge currents (e.g., 70 mA), electrospray-likemore » spectra are observed, dominated by singly and doubly protonated molecular ions. At lower currents (35 mA), many peptides exhibit extensive fragmentation, with a-, b-, c-, x-, and y-type ion series present as well as complex fragments, such as d-type ions, not previously observed with atmospheric-pressure dissociation. Though the mechanism of fragmentation is currently unclear, observations indicate it could result from the interaction of peptides with gas-phase radicals or ultraviolet radiation generated within the plasma.« less

The UAH Spinning Terrella Experiment: A Laboratory Analog for the Earth's Magnetosphere

NASA Technical Reports Server (NTRS)

Sheldon, R. B.; Gallagher, D. L.; Craven, P. D.; Whitaker, Ann F. (Technical Monitor)

2001-01-01

The UAH Spinning Terrella Experiment has been modified to include the effect of a second magnet. This is a simple laboratory demonstration of the well-known double-dipole approximation to the Earth's magnetosphere. In addition, the magnet has been biassed $\\sim$-400V which generates a DC glow discharge and traps it in a ring current around the magnet. This ring current is easily imaged with a digital camera and illustrates several significant topological properties of a dipole field. In particular, when the two dipoles are aligned, and therefore repel, they emulate a northward IMF Bz magnetosphere. Such a geometry traps plasma in the high latitude cusps as can be clearly seen in the movies. Likewise, when the two magnets are anti-aligned, they emulate a southward IMF Bz magnetosphere with direct feeding of plasma through the x-line. We present evidence for trapping and heating of the plasma, comparing the dipole-trapped ring current to the cusp-trapped population. We also present a peculiar asymmetric ring current produced in by the plasma at low plasma densities. We discuss the similarities and dissimilarities of the laboratory analog to the collisionless Earth plasma, and implications for the interpretation of IMAGE data.

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

NASA Astrophysics Data System (ADS)

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

2016-08-01

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

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…

Corona discharges and their effect on lightning attachment revisited: Upward leader initiation and downward leader interception

NASA Astrophysics Data System (ADS)

Becerra, Marley

2014-11-01

Previous studies have suggested the possibility of using glow corona discharges to control the frequency of lightning flashes to grounded objects. In order to revisit the theoretical basis of this proposal, the self-consistent leader inception and propagation model - SLIM - is used together with a two-dimensional glow corona drift model. The analysis is performed to quantify the effect of glow corona generated at the tip of ground-based objects on the initiation and propagation of upward positive connecting leaders under the influence of downward lightning leaders. It is found that the presence of glow corona does not influence the performance of Franklin lightning rods shorter than 15 m, while it slightly reduces the lateral distance of rods up to 60 m tall by a maximum of 10%. Furthermore, the results indicate that it is not possible to suppress the initiation of upward connecting leaders by means of glow corona. It is found instead that unconventional lightning protection systems based on the generation of glow corona attract downward lightning flashes in a similar way as a standard lightning rod with the same height.

Analytical Expressions for the Mixed-Order Kinetics Parameters of TL Glow Peaks Based on the two Heating Rates Method.

PubMed

Maghrabi, Mufeed; Al-Abdullah, Tariq; Khattari, Ziad

2018-03-24

The two heating rates method (originally developed for first-order glow peaks) was used for the first time to evaluate the activation energy (E) from glow peaks obeying mixed-order (MO) kinetics. The derived expression for E has an insignificant additional term (on the scale of a few meV) when compared with the first-order case. Hence, the original expression for E using the two heating rates method can be used with excellent accuracy in the case of MO glow peaks. In addition, we derived a simple analytical expression for the MO parameter. The present procedure has the advantage that the MO parameter can now be evaluated using analytical expression instead of using the graphical representation between the geometrical factor and the MO parameter as given by the existing peak shape methods. The applicability of the derived expressions for real samples was demonstrated for the glow curve of Li 2 B 4 O 7 :Mn single crystal. The obtained parameters compare very well with those obtained by glow curve fitting and with the available published data.

Hybrid method of making an amorphous silicon P-I-N semiconductor device

DOEpatents

Moustakas, Theodore D.; Morel, Don L.; Abeles, Benjamin

1983-10-04

The invention is directed to a hydrogenated amorphous silicon PIN semiconductor device of hybrid glow discharge/reactive sputtering fabrication. The hybrid fabrication method is of advantage in providing an ability to control the optical band gap of the P and N layers, resulting in increased photogeneration of charge carriers and device output.

Is Visually Guided Reaching in Early Infancy a Myth?

ERIC Educational Resources Information Center

Clifton, Rachel K.; And Others

1993-01-01

Seven infants were tested between the ages of 6 and 25 weeks to see how they would grasp objects presented in full light and glowing or sounding objects presented in total darkness. In all three conditions, the infants first grasped the objects at nearly the same time, suggesting that internal stimuli, not visual guidance, directed their actions.…

Anticipated Guilt for Not Helping and Anticipated Warm Glow for Helping Are Differently Impacted by Personal Responsibility to Help

PubMed Central

Erlandsson, Arvid; Jungstrand, Amanda Å.; Västfjäll, Daniel

2016-01-01

One important motivation for people behaving prosocially is that they want to avoid negative and obtain positive emotions. In the prosocial behavior literature however, the motivations to avoid negative emotions (e.g., guilt) and to approach positive emotions (e.g., warm glow) are rarely separated, and sometimes even aggregated into a single mood-management construct. The aim of this study was to investigate whether anticipated guilt if not helping and anticipated warm glow if helping are influenced similarly or differently when varying situational factors related to personal responsibility to help. Helping scenarios were created and pilot tests established that each helping scenario could be formulated both in a high-responsibility version and in a low-responsibility version. In Study 1 participants read high-responsibility and low-responsibility helping scenarios, and rated either their anticipated guilt if not helping or their anticipated warm glow if helping (i.e., separate evaluation). Study 2 was similar but here participants rated both their anticipated guilt if not helping and their anticipated warm glow if helping (i.e., joint evaluation). Anticipated guilt was clearly higher in the high-responsibility versions, but anticipated warm glow was unaffected (in Studies 1a and 1b), or even higher in the low-responsibility versions (Study 2). In Studies 3 (where anticipated guilt and warm glow were evaluated separately) and 4 (where they were evaluated jointly), personal responsibility to help was manipulated within-subjects. Anticipated guilt was again constantly higher in the high-responsibility versions but for many types of responsibility-manipulations, anticipated warm glow was higher in the low-responsibility versions. The results suggest that we anticipate guilt if not fulfilling our responsibility but that we anticipate warm glow primarily when doing over and beyond our responsibility. We argue that future studies investigating motivations for helping should measure both anticipated negative consequences for oneself if not helping, and anticipated positive consequences for oneself if helping. PMID:27733840

Anticipated Guilt for Not Helping and Anticipated Warm Glow for Helping Are Differently Impacted by Personal Responsibility to Help.

PubMed

Erlandsson, Arvid; Jungstrand, Amanda Å; Västfjäll, Daniel

2016-01-01

One important motivation for people behaving prosocially is that they want to avoid negative and obtain positive emotions. In the prosocial behavior literature however, the motivations to avoid negative emotions (e.g., guilt) and to approach positive emotions (e.g., warm glow) are rarely separated, and sometimes even aggregated into a single mood-management construct. The aim of this study was to investigate whether anticipated guilt if not helping and anticipated warm glow if helping are influenced similarly or differently when varying situational factors related to personal responsibility to help. Helping scenarios were created and pilot tests established that each helping scenario could be formulated both in a high-responsibility version and in a low-responsibility version. In Study 1 participants read high-responsibility and low-responsibility helping scenarios, and rated either their anticipated guilt if not helping or their anticipated warm glow if helping (i.e., separate evaluation). Study 2 was similar but here participants rated both their anticipated guilt if not helping and their anticipated warm glow if helping (i.e., joint evaluation). Anticipated guilt was clearly higher in the high-responsibility versions, but anticipated warm glow was unaffected (in Studies 1a and 1b), or even higher in the low-responsibility versions (Study 2). In Studies 3 (where anticipated guilt and warm glow were evaluated separately) and 4 (where they were evaluated jointly), personal responsibility to help was manipulated within-subjects. Anticipated guilt was again constantly higher in the high-responsibility versions but for many types of responsibility-manipulations, anticipated warm glow was higher in the low-responsibility versions. The results suggest that we anticipate guilt if not fulfilling our responsibility but that we anticipate warm glow primarily when doing over and beyond our responsibility. We argue that future studies investigating motivations for helping should measure both anticipated negative consequences for oneself if not helping, and anticipated positive consequences for oneself if helping.

Warm glow, free-riding and vehicle neutrality in a health-related contingent valuation study.

PubMed

Hackl, Franz; Pruckner, Gerald J

2005-03-01

Criticism of contingent valuation (CV) stresses warm glow and free-riding as possible causes for biased willingness to pay figures. We present an empirical framework to study the existence of warm glow and free-riding in hypothetical WTP answers based on a CV survey for the measurement of health-related Red Cross services. Both in conventional double-bounded and spike models we do not find indication of warm glow phenomena and free-riding behaviour. The results are very robust and insensitive to the applied payment vehicles. Theoretical objections against CV do not find sufficient empirical support.

Study of the glow curve structure of the minerals separated from black pepper (Piper nigrum L.)

NASA Astrophysics Data System (ADS)

Guzmán, S.; Ruiz Gurrola, B.; Cruz-Zaragoza, E.; Tufiño, A.; Furetta, C.; Favalli, A.; Brown, F.

2011-04-01

The inorganic mineral fraction extracted from black pepper (Piper nigrum L.) has been analysed using a thermoluminescence (TL) method, investigating the glow curve structure, including an evaluation of the kinetic parameters. Different grain sizes, i.e. 10, 74, and 149 μm, were selected from commercial black pepper. The X-ray diffraction of the inorganic fraction shows that quartz is the main mineral present in it. The samples were exposed to 1-25 kGy doses by gamma rays of 60Co in order to analyse the thermally stimulated luminescence response as a function of the delivered dose. The glow curves show a complex structure for different grain sizes of the pepper mineral samples. The fading of the TL signal at room temperature was obtained after irradiation, and it was observed that the maximum peaks of the glow curves shift towards higher values of the temperature when the elapsed time from irradiation increases. It seems that the fading characteristic may be related to a continuous trap distribution responsible for the complex structure of the glow curve. Similar glow curves structure behaviour was found under ultraviolet irradiation of the samples. The activation energy and the frequency factor were determined from the glow curves of different grain sizes using a deconvolution programme because of the evident complexity of the structure.

Dark Skies: Local Success, Global Challenge

NASA Astrophysics Data System (ADS)

Lockwood, G. W.

2009-01-01

The Flagstaff, Arizona 1987 lighting code reduced the growth rate of man-made sky glow by a third. Components of the code include requirements for full cutoff lighting, lumens per acre limits in radial zones around observatories, and use of low-pressure sodium monochromatic lighting for roadways and parking lots. Broad public acceptance of Flagstaff's lighting code demonstrates that dark sky preservation has significant appeal and few visibility or public safety negatives. An inventory by C. Luginbuhl et al. of the light output and shielding of a sampling of various zoning categories (municipal, commercial, apartments, single-family residences, roadways, sports facilities, industrial, etc.), extrapolated over the entire city, yields a total output of 139 million lumens. Commercial and industrial sources account for 62% of the total. Outdoor sports lighting increases the total by 24% on summer evenings. Flagstaff's per capita lumen output is 2.5 times greater than the nominal 1,000 lumens per capita assumed by R. Garstang in his early sky glow modeling work. We resolved the discrepancy with respect to Flagstaff's measured sky glow using an improved model that includes substantial near ground attenuation by foliage and structures. A 2008 university study shows that astronomy contributes $250M annually to Arizona's economy. Another study showed that the application of lighting codes throughout Arizona could reduce energy consumption significantly. An ongoing effort led by observatory directors statewide will encourage lighting controls in currently unregulated metropolitan areas whose growing sky glow threatens observatory facilities more than 100 miles away. The national press (New York Times, the New Yorker, the Economist, USA Today, etc.) have publicized dark sky issues but frequent repetition of the essential message and vigorous action will be required to steer society toward darker skies and less egregious waste.

Broad-beam high-current dc ion source based on a two-stage glow discharge plasma.

PubMed

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

2010-02-01

We have designed, made, and demonstrated a broad-beam, dc, ion source based on a two-stage, hollow-cathode, and glow discharges plasma. The first-stage discharge (auxiliary discharge) produces electrons that are injected into the cathode cavity of a second-stage discharge (main discharge). The electron injection causes a decrease in the required operating pressure of the main discharge down to 0.05 mTorr and a decrease in required operating voltage down to about 50 V. The decrease in operating voltage of the main discharge leads to a decrease in the fraction of impurity ions in the ion beam extracted from the main gas discharge plasma to less than 0.2%. Another feature of the source is a single-grid accelerating system in which the ion accelerating voltage is applied between the plasma itself and the grid electrode. The source has produced steady-state Ar, O, and N ion beams of about 14 cm diameter and current of more than 2 A at an accelerating voltage of up to 2 kV.

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

DOEpatents

Staebler, David L.; Zanzucchi, Peter J.

1980-01-01

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

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…

Automated control of linear constricted plasma source array

DOEpatents

Anders, Andre; Maschwitz, Peter A.

2000-01-01

An apparatus and method for controlling an array of constricted glow discharge chambers are disclosed. More particularly a linear array of constricted glow plasma sources whose polarity and geometry are set so that the contamination and energy of the ions discharged from the sources are minimized. The several sources can be mounted in parallel and in series to provide a sustained ultra low source of ions in a plasma with contamination below practical detection limits. The quality of film along deposition "tracks" opposite the plasma sources can be measured and compared to desired absolute or relative values by optical and/or electrical sensors. Plasma quality can then be adjusted by adjusting the power current values, gas feed pressure/flow, gas mixtures or a combination of some or all of these to improve the match between the measured values and the desired values.

Enhancement of First Wall Damage in Iter Type Tokamak due to Lenr Effects

NASA Astrophysics Data System (ADS)

Lipson, Andrei G.; Miley, George H.; Momota, Hiromu

In recent experiments with pulsed periodic high current (J ~ 300-500 mA/cm2) D2-glow discharge at deuteron energies as low as 0.8-2.45 keV a large DD-reaction yield has been obtained. Thick target yield measurement show unusually high DD-reaction enhancement (at Ed = 1 keV the yield is about nine orders of magnitude larger than that deduced from standard Bosch and Halle extrapolation of DD-reaction cross-section to lower energies) The results obtained in these LENR experiments with glow discharge suggest nonnegligible edge plasma effects in the ITER TOKAMAK that were previously ignored. In the case of the ITER DT plasma core, we here estimate the DT reaction yield at the metal edge due to plasma ion bombardment of the first wall and/or divertor materials.

Transmission characteristics of microwave in a glow-discharge dusty plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jia, Jieshu; Yuan, Chengxun, E-mail: yuancx@hit.edu.cn; Gao, Ruilin

2016-07-15

In this study, the propagation characteristics of electromagnetic wave in a glow discharge plasma with dust particles are experimentally investigated. A helium alternating current glow discharge plasmas have been successfully generated. Measurements of the plasma parameters using Langmuir probes, in the absence of dust particles, provide plasma densities (n{sub e}) of 10{sup 17 }m{sup −3} and electron temperatures (T{sub e}) ranging from 2 to 4 eV. Dusty plasmas are made by adding 30 nm radius aluminum oxide (Al{sub 2}O{sub 3}) particles into the helium plasma. The density of the dust particle (n{sub d}) in the device is about 10{sup 11}–10{sup 12 }m{sup −3}. Themore » propagation characteristics of electromagnetic waves are determined by a vector network analyzer with 4–6 GHz antennas. An apparent attenuation by the dust is observed, and the measured attenuation data are approximately in accordance with the theoretical calculations. The effects of gas pressure and input power on the propagation are also investigated. Results show that the transmission attenuation increases with the gas pressure and input power, the charged dust particles play a significant role in the microwave attenuation.« less

Exploration to generate atmospheric pressure glow discharge plasma in air

NASA Astrophysics Data System (ADS)

Wenzheng, LIU; Chuanlong, MA; Shuai, ZHAO; Xiaozhong, CHEN; Tahan, WANG; Luxiang, ZHAO; Zhiyi, LI; Jiangqi, NIU; Liying, ZHU; Maolin, CHAI

2018-03-01

Atmospheric pressure glow discharge (APGD) plasma in air has high application value. In this paper, the methods of generating APGD plasma in air are discussed, and the characteristics of dielectric barrier discharge (DBD) in non-uniform electric field are studied. It makes sure that APGD in air is formed by DBD in alternating current electric field with using the absorbing electron capacity of electret materials to provide initial electrons and to end the discharge progress. Through designing electric field to form two-dimensional space varying electric field and three-dimensional space varying electric field, the development of electron avalanches in air-gap is suppressed effectively and a large space of APGD plasma in air is generated. Further, through combining electrode structures, a large area of APGD plasma in air is generated. On the other hand, by using the method of increasing the density of initial electrons, millimeter-gap glow discharge in atmospheric pressure air is formed, and a maximum gap distance between electrodes is 8 mm. By using the APGD plasma surface treatment device composed of contact electrodes, the surface modification of high polymer materials such as aramid fiber and polyester are studied and good effect of modifications is obtained. The present paper provides references for the researchers of industrial applications of plasma.

Global Statistics of Bolides in the Terrestrial Atmosphere

NASA Astrophysics Data System (ADS)

Chernogor, L. F.; Shevelyov, M. B.

2017-06-01

Purpose: Evaluation and analysis of distribution of the number of meteoroid (mini asteroid) falls as a function of glow energy, velocity, the region of maximum glow altitude, and geographic coordinates. Design/methodology/approach: The satellite database on the glow of 693 mini asteroids, which were decelerated in the terrestrial atmosphere, has been used for evaluating basic meteoroid statistics. Findings: A rapid decrease in the number of asteroids with increasing of their glow energy is confirmed. The average speed of the celestial bodies is equal to about 17.9 km/s. The altitude of maximum glow most often equals to 30-40 km. The distribution law for a number of meteoroids entering the terrestrial atmosphere in longitude and latitude (after excluding the component in latitudinal dependence due to the geometry) is approximately uniform. Conclusions: Using a large enough database of measurements, the meteoroid (mini asteroid) statistics has been evaluated.

RF assisted Glow Discharge Condition experiment for SST-1 Tokamak

NASA Astrophysics Data System (ADS)

Raval, Dilip; Khan, Ziauddin; George, Siju; Dhanani, Kalpeshkumar R.; Paravastu, Yuvakiran; Semwal, Pratibha; Thankey, Prashant; Shoaib Khan, Mohammad; Kakati, Bharat; Pradhan, Subrata

2017-04-01

Impurity control reduces the radiation loss from plasma and hence enhances the plasma operation. Oxygen and water vapors are the most common impurities in tokamak devices. Water vapour can be reduced with extensive baking while in order to have a significant reduction in oxygen it is necessary to use glow discharge condition (GDC). RF assisted glow discharge cleaning system will be implemented to remove low z impurities at PFC installed SST-1 vacuum vessel. A RF assisted Glow discharge conditioning is studied at laboratory to find the optimum operating parameters in a view to implement at SST-1 tokamak. Helium is used as a fuel gas in the present experiment. It is observed that the ultimate impurity level is reduced significantly below to the accepted level for plasma operation after RF assisted GDC. The experimental findings of RF assisted Glow discharge conditioning is discussed in details in this paper.

Dynamics of multiple double layers in high pressure glow discharge in a simple torus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar Paul, Manash, E-mail: manashkr@gmail.com; Sharma, P. K.; Thakur, A.

2014-06-15

Parametric characterization of multiple double layers is done during high pressure glow discharge in a toroidal vessel of small aspect ratio. Although glow discharge (without magnetic field) is known to be independent of device geometry, but the toroidal boundary conditions are conducive to plasma growth and eventually the plasma occupy the toroidal volume partially. At higher anode potential, the visibly glowing spots on the body of spatially extended anode transform into multiple intensely luminous spherical plasma blob structures attached to the tip of the positive electrode. Dynamics of multiple double layers are observed in argon glow discharge plasma in presencemore » of toroidal magnetic field. The radial profiles of plasma parameters measured at various toroidal locations show signatures of double layer formation in our system. Parametric dependence of double layer dynamics in presence of toroidal magnetic field is presented here.« less

Glow discharge cleaning of vacuum switch tubes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hayashi, T.; Toya, H.

1991-10-01

This paper reports that glow discharge cleaning has ben advancing as a means of degassing vacuum chambers constructed for a large accelerator or for nuclear fusion research. To clean the whole surface of parts inside a vacuum switch tube (VST), a new technique is tried which generates glow discharge between the inner electrodes and copper grid surrounding it. Photographic observation reveals that the glow discharge spreads out and cleans the whole surface inside the VST. A breakdown test between the inner electrodes shows the effect of the cleaning with this technique. Higher breakdown voltage between the inner electrodes is attainedmore » by performing this glow discharge cleaning in argon rather than hydrogen gas. The difference of the cleaning effect seems to be attributed to that of the energy transfer from ion species to the absorbed molecules and microprotrusions on the surfaces.« less

Thermoluminescence dosimetry properties of new Cu doped CaF(2) nanoparticles.

PubMed

Zahedifar, M; Sadeghi, E

2013-12-01

Nanoparticles of Cu-doped calcium fluoride were synthesised by using the hydrothermal method. The structure of the prepared nanomaterial was characterised by the X-ray diffraction (XRD) pattern and energy dispersive spectrometer. The particle size of 36 nm was calculated from the XRD data. Its shape and size were also observed by scanning electron microscope. Thermoluminescence (TL) and photoluminescence of the produced phosphor were also considered. The computerised glow curve deconvolution procedure was used to identify the number of glow peaks included in the TL glow curve of the CaF2:Cu nanoparticles. The TL glow curve contains two overlapping glow peaks at ∼413 and 451 K. The TL response of this phosphor was studied for different Cu concentrations and the maximum sensitivity was found at 1 mol% of Cu impurity. Other dosimetric characteristics of the synthesised nanophosphor are also presented and discussed.

Orbiter glow observations at high spectral resolution

NASA Technical Reports Server (NTRS)

Kendall, D. J. W.; Mende, S. B.; Yn, E. J. ADMCDADE, I. C. AEMENDE, S. B.

1985-01-01

An experiment flow on mission STS 41-G as part of the Canadian complement of experiments was designed to obtain relatively high resolution spectra of the Orbiter glow phenomenon over limited spectral regions centered on prominent upper atmospheric emissions. Observations were carried out successfully at altitudes of 360 km and 230 km although those at the lower altitude were limited by degradation of the image intensifier. Definitive glow results were obtained at the end of a thruster firing which showed the spectrum to be a continuum at a resolution of approximately 0.4 nm centered at a wavelength of 360 nm. Results at other wavelengths in the absence of any firings strongly suggest that the Orbiter glow is a continuum throughout the spectral region 550 nm to 760 nm. A discussion is presented that considers the reaction NO + O2 as being a possible candidate for the mechanism producing the shuttle glow.

Io in Eclipse, Movie

NASA Technical Reports Server (NTRS)

2001-01-01

Glowing spots of hot lava and ethereal auroral emissions are highlighted against blackness in this sequence of 48 frames from NASA's Cassini spacecraft, which show Jupiter's moon Io in the darkness of the giant planet's shadow.

The sequence was recorded over a two-hour interval that spanned nearly an entire eclipse on Jan. 1, 2001. Although no sunlight shines on the moon during an eclipse, two types of glows can be seen. The bright points of light are the glows of hot lava from active volcanoes. The brightest is the volcano Pele, which appears to be erupting steadily despite its great intensity. To the right of Pele and slightly above it is a pair of bright spots associated with the volcano Pillan, the source of a major eruption in 1997. NASA's Galileo spacecraft and Hubble Space Telescope saw that 1997 eruption of Pillan dwarf the energy output from neighboring Pele, but Pillan's eruption has waned over the past 30 months to the pair of small hot spots seen here. Another volcano, seen below and to the right of Pele, varies on a time scale of days. This sequence of images illustrates the great variations in intensity and longevity of Io's volcanic eruptions.

The second type of glow seen on Io during eclipse is a set of faint, diffuse emissions due to atmospheric auroras. Similar to the aurora borealis and aurora australis on Earth, Io's auroras are caused by the collisions of charged particles with gases in Io's tenuous atmosphere. A faint ring encircles the moon, while brighter glows are concentrated near the moon's equator. These equatorial glows are seen here gradually shifting clockwise in location as the eclipse progresses, due to the changing orientation of Jupiter's magnetic field. This is a new result which confirms that these visible auroras, like their counterparts seen at ultraviolet wavelengths, are caused by electrical currents that flow between Io and Jupiter.

The original images were taken through a clear filter of Cassini's narrow-angle camera from a distance of over 10 million kilometers (6.3 million miles), with a resolution of 61 kilometers (40 miles) per pixel. The images have been cropped and processed to remove scattered light.

Cassini is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages Cassini for NASA's Office of Space Science, Washington, D.C.

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

DOEpatents

Christophorou, Loucas G.; Hunter, Scott R.

1990-01-01

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

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

DOEpatents

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

1990-06-26

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

LOX/Methane Main Engine Glow Plug Igniter Tests and Modeling

NASA Technical Reports Server (NTRS)

Breisacher, Kevin; Ajmani, Kumud

2009-01-01

Ignition data for tests with a LOX/methane igniter that utilized a glow plug as the ignition source are presented. The tests were conducted in a vacuum can with thermally conditioned (cold) hardware. Data showing the effects of glow plug geometry, type, and igniter operating conditions are discussed. Comparisons between experimental results and multidimensional, transient computer models are also made.

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

DOEpatents

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

1988-06-28

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

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bo, Zheng; Qian, Jiajing; Duan, Liangping

2015-05-15

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.

Efficiency of surface cleaning by a glow discharge for plasma spraying coating

NASA Astrophysics Data System (ADS)

Kadyrmetov, A. M.; Kashapov, N. F.; Sharifullin, S. N.; Saifutdinov, A. I.; Fadeev, S. A.

2016-06-01

The article presents the results of experimental studies of the quality of cleaning steel surfaces by a glow discharge for plasma spraying. Shows the results of measurements of the angle of surface wetting and bond strength of the plasma coating to the surface treated. The dependence of the influence of the glow discharge power, chamber pressure, distance between the electrodes and the processing time of the surface on cleaning efficiency. Optimal fields of factors is found. It is shown increase joint strength coating and base by 30-80% as a result of cleaning the substrate surface by a glow discharge plasma spraying.

The analysis of thermoluminescent glow peaks of natural calcite after beta irradiation.

PubMed

Yildirim, R Güler; Kafadar, V Emir; Yazici, A Necmeddin; Gün, Esen

2012-09-01

In this study, the thermoluminescence properties of natural calcite samples were examined in detail. The glow curve of the sample irradiated with beta radiation shows two main peaks, P1 (at 115 °C) and P4 (at 254 °C). The additive dose, variable heating rate, computer glow curve deconvolution, peak shape and three point methods have been used to evaluate the trapping parameters, namely the order of kinetics (b), activation energy (E) and the frequency factor (s) associated with the dosimetric thermoluminescent glow peaks (P1 and P4) of natural calcite after different dose levels with beta irradiation.

Medium resolution spectra of the shuttle glow in the visible region of the spectrum

NASA Technical Reports Server (NTRS)

Viereck, R. A.; Murad, E.; Pike, C. P.; Mende, S. B.; Swenson, G. R.; Culbertson, F. L.; Springer, B. C.

1992-01-01

Recent spectral measurements of the visible shuttle glow (lambda = 400 - 800 nm) at medium resolution (1 nm) reveal the same featureless continuum with a maximum near 680 nm that was reported previously. This is also in good agreement with recent laboratory experiments that attribute the glow to the emissions of NO2 formed by the recombination of O + NO. The data that are presented were taken from the aft flight deck with a hand-held spectrograph and from the shuttle bay with a low-light-level television camera. Shuttle glow images and spectra are presented and compared with laboratory data and theory.

Irradiation of silver and agar/silver nanoparticles with argon, oxygen glow discharge plasma, and mercury lamp.

PubMed

Ahmad, Mahmoud M; Abdel-Wahab, Essam A; El-Maaref, A A; Rawway, Mohammed; Shaaban, Essam R

2014-01-01

The irradiation effect of argon, oxygen glow discharge plasma, and mercury lamp on silver and agar/silver nanoparticle samples is studied. The irradiation time dependence of the synthesized silver and agar/silver nanoparticle absorption spectra and their antibacterial effect are studied and compared. In the agar/silver nanoparticle sample, as the irradiation time of argon glow discharge plasma or mercury lamp increases, the peak intensity and the full width at half maximum, FWHM, of the surface plasmon resonance absorption band is increased, however a decrease of the peak intensity with oxygen glow plasma has been observed. In the silver nanoparticle sample, as the irradiation time of argon, oxygen glow discharge plasma or mercury lamp increases, the peak intensity of the surface plasmon resonance absorption band is increased, however, there is no significant change in the FWHM of the surface plasmon resonance absorption band. The SEM results for both samples showed nanoparticle formation with mean size about 50 nm and 40 nm respectively. Throughout the irradiation time with the argon, oxygen glow discharge plasma or mercury lamp, the antibacterial activity of several kinds of Gram-positive and Gram-negative bacteria has been examined.

Experimental investigation of the 100 keV X-ray dose response of the high-temperature thermoluminescence in LiF:Mg,Ti (TLD-100): theoretical interpretation using the unified interaction model.

PubMed

Livingstone, J; Horowitz, Y S; Oster, L; Datz, H; Lerch, M; Rosenfeld, A; Horowitz, A

2010-03-01

The dose response of LiF:Mg,Ti (TLD-100) chips was measured from 1 to 50,000 Gy using 100 keV X rays at the European Synchroton Radiation Facility. Glow curves were deconvoluted into component glow peaks using a computerised glow curve deconvolution (CGCD) code based on first-order kinetics. The normalised dose response, f(D), of glow peaks 4 and 5 and 5b (the major components of composite peak 5), as well as peaks 7 and 8 (two of the major components of the high-temperature thermoluminescence (HTTL) at high levels of dose) was separately determined and theoretically interpreted using the unified interaction model (UNIM). The UNIM is a nine-parameter model encompassing both the irradiation/absorption stage and the thermally induced relaxation/recombination stage with an admixture of both localised and delocalised recombination mechanisms. The effects of radiation damage are included in the present modelling via the exponential removal of luminescent centres (LCs) at high dose levels. The main features of the experimentally measured dose response are: (i) increase in f(D)(max) with glow peak temperature, (ii) increase in D(max) (the dose level at which f(D)(max) occurs) with increasing glow peak temperature, and (iii) decreased effects of radiation damage with increasing glow peak temperature. The UNIM interpretation of this behaviour requires both strongly decreasing values of ks (the relative contribution of localised recombination) as a function of glow peak temperature and, as well, significantly different values of the dose-filling constants of the trapping centre (TC) and LC for peaks 7 and 8 than those used for peaks 4 and 5. This suggests that different TC/LC configurations are responsible for HTTL. The relative intensity of peak 5a (a low-temperature satellite of peak 5 arising from localised recombination) was found to significantly increase at higher dose levels due to preferential electron and hole population of the trapping/recombination complex giving rise to composite glow peak 5. It is also demonstrated that possible changes in the trapping cross section of the LC and the competitive centres due to increasing sample/glow peak temperature do not significantly influence these observations/conclusions.

Survey of ultraviolet shuttle glow

NASA Technical Reports Server (NTRS)

Spear, K. A.; Uckler, G. J.; Tobiska, K.

1985-01-01

The University of Colorado Get Away Special (GAS) project utilizes the efforts of its students to place experiments on the shuttle. The objective of one experiment, the shuttle glow study, is to conduct a general survey of emissions in the ultraviolet near vehicle surfaces. An approximate wavelength range of 1900 to 3000 A will be scanned to observe predominant features. Special emphasis will be placed on studying the band structure of NO near 2000 A and the Mg+ line at 2800 A. The spectrometer, of Ebert-Faste 1/8-meter design, will perform the experiment during spacecraft night. It will be oriented such that the optical axis points to the cargo bay zenith. In order to direct the field-of-view of the instrument onto the shuttle vertical stabilizer (tail), a mirror assembly is employed. The mirror system has been designed to rotate through 7.5 degrees of arc using 10 positions resulting in a spatial resolution of 30 x 3 cm, with the larger dimension corresponding to the horizontal direction. Such a configuration can be attained from the forwardmost position in the cargo bay. Each spatial position will be subjected to a full spectral scan with a resolution on the order of 10 A.

Sensitive Determination of Cd in Small-Volume Samples by Miniaturized Liquid Drop Anode Atmospheric Pressure Glow Discharge Optical Emission Spectrometry.

PubMed

Jamroz, Piotr; Greda, Krzysztof; Dzimitrowicz, Anna; Swiderski, Krzysztof; Pohl, Pawel

2017-06-06

A novel liquid drop anode (LDA) direct current atmospheric pressure glow discharge (dc-APGD) system was applied for direct determination of Cd in liquid microsamples (50 μL) by optical emission spectrometry (OES). The microdischarge was generated in open-to-air atmosphere between a solid pin type tungsten cathode and a liquid drop placed on a graphite disk anode. The arrangement of the graphite disk placed on a PTFE chip platform as well as the solid pin type cathode was simple and robust. The limit of detection (LOD) of Cd for the developed LDA-APGD-OES method was 0.20-0.40 μg L -1 , while precision (as the relative standard deviation for the repeated measurements) was within 2-5%. By using the liquid drop of 50 μL, the linearity range of 1-1000 μg L -1 was achieved. The effect of addition of the low-molecular weight (LMW) organic compounds, easily ionized elements (EIEs), i.e., Ca, K, Mg, and Na, as well as the foreign ions (Al, Cu, Fe, Mn, Zn) to the solution on the in situ atomization and excitation processes occurred during operation of the LDA-APGD system, and the response of Cd was studied. Validation of the proposed method was demonstrated by analysis of Lobster hepatopancreas (TORT-2), pig kidney (ERM-BB186), and groundwater (ERM-CA615) certified reference materials (CRMs) and recoveries of Cd from water samples spiked with 25 μg L -1 of Cd. Very good agreement between the found and certified values of Cd in the CRMs (the recoveries were within the range of 96.3-99.6%) indicated trueness of the method and its reliability for determination of traces of Cd. In the case of the spiked water samples, the recoveries obtained were in the range from 95.2 to 99.5%.

Comparison of pulse glow discharge-ion mobility spectrometry and liquid chromatography with tandem mass spectrometry based on multiplug filtration cleanup for the analysis of tricaine mesylate residues in fish and water.

PubMed

Zou, Nan; Chen, Ronghua; Qin, Yuhong; Song, Shuangyu; Tang, Xinglin; Pan, Canping

2016-09-01

Analytical methods based on multiplug filtration cleanup coupled with pulse glow discharge-ion mobility spectrometry and liquid chromatography tandem mass spectrometry were developed for the analysis of tricaine mesylate residue in fish and fish-raising water samples. A silica fiber holder and an appropriate new interface were designed to make the direct introduction of the fiber into the pulse glow discharge-ion mobility spectrometry introduction mechanism. The multiplug filtration cleanup method with adsorption mixtures was optimized for the determination of tricaine mesylate in fish samples. Good linear relationships were obtained by the two methods. For fish samples, limits of detection were 6 and 0.6 μg/kg by ion mobility spectrometry and liquid chromatography with tandem mass spectrometry, respectively. The matrix effect of the established liquid chromatography tandem mass spectrometry method was negligible for fish samples but that of the ion mobility spectrometry method was not. The two methods were compared. The ion mobility spectrometry system could be used a rapid screening tool on site with the advantage of rapidity, simplicity, and portability, and the liquid chromatography tandem mass spectrometry system could be used for validation in laboratory conditions with the advantage of lower limit of detection, stability, and precision. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Examination of interior surfaces using glow-discharge illumination

DOEpatents

Lord, David E.; Petrini, Richard R.; Carter, Gary W.

1978-01-01

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

Electrical and optical properties of Ar/NH{sub 3} atmospheric pressure plasma jet

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, Zheng-Shi, E-mail: changzhsh1984@163.com, E-mail: gjzhang@xjtu.edu.cn; Yao, Cong-Wei; Chen, Si-Le

Inspired by the Penning effect, we obtain a glow-like plasma jet by mixing ammonia (NH{sub 3}) into argon (Ar) gas under atmospheric pressure. The basic electrical and optical properties of an atmospheric pressure plasma jet (APPJ) are investigated. It can be seen that the discharge mode transforms from filamentary to glow-like when a little ammonia is added into the pure argon. The electrical and optical analyses contribute to the explanation of this phenomenon. The discharge mode, power, and current density are analyzed to understand the electrical behavior of the APPJ. Meanwhile, the discharge images, APPJ's length, and the components ofmore » plasma are also obtained to express its optical characteristics. Finally, we diagnose several parameters, such as gas temperature, electron temperature, and density, as well as the density number of metastable argon atoms of Ar/NH{sub 3} APPJ to help judge the usability in its applications.« less

Numerical simulation of an oxygen-fed wire-to-cylinder negative corona discharge in the glow regime

NASA Astrophysics Data System (ADS)

Yanallah, K.; Pontiga, F.; Castellanos, A.

2011-02-01

Negative glow corona discharge in flowing oxygen has been numerically simulated for a wire-to-cylinder electrode geometry. The corona discharge is modelled using a fluid approximation. The radial and axial distributions of charged and neutral species are obtained by solving the corresponding continuity equations, which include the relevant plasma-chemical kinetics. Continuity equations are coupled with Poisson's equation and the energy conservation equation, since the reaction rate constants may depend on the electric field and temperature. The experimental values of the current-voltage characteristic are used as input data into the numerical calculations. The role played by different reactions and chemical species is analysed, and the effect of electrical and geometrical parameters on ozone generation is investigated. The reliability of the numerical model is verified by the reasonable agreement between the numerical predictions of ozone concentration and the experimental measurements.

On the mechanism of pattern formation in glow dielectric barrier discharge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qiao, Yajun; Li, Ben; Ouyang, Jiting, E-mail: jtouyang@bit.edu.cn

2016-01-15

The formation mechanism of pattern in glow dielectric barrier discharge is investigated by two-dimensional fluid modeling. Experimental results are shown for comparison. The simulation results show that the non-uniform distribution of space charges makes the discharge be enhanced in the high-density region but weakened in its neighborhood, which is considered as an activation-inhibition effect. This effect shows through during a current pulse (one discharge event) but also in a certain period of time after discharge that determines a driving frequency range for the non-uniformity of space charges to be enhanced. The effects of applied voltage, surface charge, electrode boundary, andmore » external field are also discussed. All these factors affect the formation of dielectric-barrier-discharge pattern by changing the distribution or the dynamics of space charges and hence the activation-inhibition effect of non-uniform space charges.« less

An electromagnetic railgun accelerator: a generator of strong shock waves in channels

NASA Astrophysics Data System (ADS)

Bobashev, S. V.; Zhukov, B. G.; Kurakin, R. O.; Ponyaev, S. A.; Reznikov, B. I.

2014-11-01

Processes that accompany the generation of strong shock waves during the acceleration of a free plasma piston (PP) in the electromagnetic railgun channel have been experimentally studied. The formation of shock waves in the railgun channel and the motion of a shock-wave-compressed layer proceed (in contrast to the case of a classical shock tube) in a rather strong electric field (up to 300 V/cm). The experiments were performed at the initial gas pressures in the channel ranging from 25 to 500 Torr. At 25 Torr, the shock-wave Mach numbers reached 32 in argon and 16 in helium. At high concentrations of charged particles behind the shock wave, the electric field causes the passage of a part of the discharge current through the volume of the shock-wave-compressed layer, which induces intense glow comparable with that of the PP glow.

Flush-mounted probe diagnostics for argon glow discharge plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Liang, E-mail: xld02345@mail.ustc.edu.cn; Cao, Jinxiang; Liu, Yu

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.more » 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.« less

Immobilization of proteins on glow discharge treated polymers

NASA Astrophysics Data System (ADS)

Kiaei, D.; Safranj, A.; Chen, J. P.; Johnston, A. B.; Zavala, F.; Deelder, A.; Castelino, J. B.; Markovic, V.; Hoffman, A. S.

Certain glow discharge-treated surfaces have been shown to enhance retention of adsorbed proteins. On the basis of this phenomenon, we have investigated the possibility of immobilizing (a) albumin for developing thromboresistant and non-fouling surfaces, (b) antibodies for immuno-diagnostic assays and (c) enzymes for various biosensors and industrial bioprocesses. Albumin retention was highest on surfaces treated with tetrafluoroethylene (TFE) compared to untreated surfaces or other glow discharge treatments studied. Preadsorption of albumin on TFE-treated surfaces resulted in low fibrinogen adsorption and platelet adhesion. IgG retention was also highest on TFE-treated surfaces. The lower detection limits of both malaria antigen and circulating anodic antigen of the schistosomiasis worm were enhanced following glow discharge treatment of the assay plates with TFE. Both TFE and tetrachloroethylene (TCE) glow discharge treated surfaces showed high retention of adsorbed horseradish peroxidase (HRP). However, the retained specific activity of HRP after adsorption on TCE-treated surfaces was remarkably higher than on TFE-treated surfaces.

TL and OSL characterization of Eu3+ doped Y2O3: Application in dosimetry

NASA Astrophysics Data System (ADS)

Shivaramu, N. J.; Coetsee, E.; Swart, H. C.

2018-05-01

Thermoluminescence (TL) and optically stimulated luminescence (OSL) properties of beta irradiated Eu3+ doped Y2O3 nanophosphor have been investigated in this paper. The Eu3+ doped Y2O3 nanophosphor was synthesized by solution combustion technique and synthesized material was annealed at 900°C. The annealed materials were exposed to β-ray for various dose. TL glow with prominent peak at 403 K and weak glow peak at 660 K were observed in all irradiated samples. It is found that TL glow peaks intensity linearly increases with increase in β-dose from 8.125 - 40.625 Gy. The TL kinetic parameters were calculated using glow curve deconvoluted (GCD) and peak shape methods. The TL glows exhibits general order kinetics. Intense continuous wave optical stimulated luminescence (CW-OSL) was observed in the sample. These material exhibits linearity at low dose, good reproducibility and response of intense OSL and hence, these results suggests that this material may be suitable for dosimetry applications.

Studying Townsend and glow modes in an atmospheric-pressure DBD using mass spectrometry

NASA Astrophysics Data System (ADS)

McKay, Kirsty; Donaghy, David; He, Feng; Bradley, James W.

2018-01-01

Ambient molecular beam mass spectrometry has been employed to examine the effects of the mode of operation and the excitation waveform on the ionic content of a helium-based atmospheric-pressure parallel plate dielectric barrier discharge. By applying 10 kHz microsecond voltage pulses with a nanosecond rise times and 10 kHz sinusoidal voltage waveforms, distinctly different glow and Townsend modes were produced, respectively. Results showed a significant difference in the dominant ion species between the two modes. In the Townsend mode, molecular oxygen ions, atomic oxygen anions and nitric oxide anions are the most abundant species, however, in the glow mode water clusters ions and hydrated nitric oxygen anions dominate. Several hypotheses are put forward to explain these differences, including low electron densities and energies in the Townsend mode, more efficient ionization of water molecules through penning ionization and charge exchange with other species in glow mode, and large temperature gradients due to the pulsed nature of the glow mode, leading to more favorable conditions for cluster formation.

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.

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.

In-flight observation of long duration gamma-ray glows by aircraft

NASA Astrophysics Data System (ADS)

Kochkin, Pavlo; (Lex) van Deursen, A. P. J.; de Boer, Alte; Bardet, Michiel; Allasia, Cedric; Boissin, Jean Francois; Ostgaard, Nikolai

2017-04-01

The Gamma-Ray Glow is a long-lasting (several seconds to minutes) X- and gamma radiation presumably originated from high-electric field of thunderclouds. Such glows were previously observed by aircraft, balloons, and from the ground. When detected on ground with other particles, i.e. electrons and neutrons, they are usually called Thunderstorm Ground Enhancements (TGEs). Their measured spectra are often consistent with Relativistic Runaway Electron Avalanche (RREA) mechanism. That is why RREA is a commonly accepted explanation for their existence. The gamma-ray glows are observed to be interrupted by lightning discharge, which terminates the high-electric field region. In January 2016 an Airbus A340 factory test aircraft was performing intentional flights through thunderstorms over Northern Australia. The aircraft was equipped with a dedicated in-flight lightning detection system called ILDAS (http://ildas.nlr.nl). The system also contained two scintillation detectors each with 38x38 mm cylinder LaBr3 crystals. While being at 12 km altitude the system detected a gamma-ray flux enhancement 30 times the background counts. It lasted for 20 seconds and was abruptly terminated by a lightning flash. The flash hit the aircraft and its parameters were recorded with 10 ns sampling time including gamma radiation. Ground-based lightning detection network WWLLN detected 4 strikes in the nearby region, all in association with the same flash. The ILDAS system recorded the time-resolved spectrum of the glow. In 6 minutes, after making a U-turn, the aircraft passed the same glow region. Smaller gamma-ray enhancement was again detected. In this presentation we will show the mapped event timeline including airplane, gamma-ray glow, WWLLN, and cloud data. We will discuss the glow's properties, i.e. intensity and differential spectrum, and its possible origin. This result will also be compared to previously reported observations.

Effects of time-temperature profiles on glow curves of germanium-doped optical fibre

NASA Astrophysics Data System (ADS)

Lam, S. E.; Alawiah, A.; Bradley, D. A.; Mohd Noor, N.

2017-08-01

The Germanium (Ge) doped silica optical fibres have demonstrated the great potential to be developed as a thermoluminescent (TL) dosimeter that can be used in various applications in radiotherapy, diagnostic radiology, UV dosimetry system and food irradiation industry. Different time-temperature profile (TTP) parameters of the TL reader have been employed by many researchers in various of TL studies. Nevertheless, none of those studies adequately addressed the effects of the reader's preheat temperature and heating rate on the kinetic parameters of the TL glow curve specifically, the Ge-doped silica optical fibres. This research addresses the issue of TTP parameters with special attention to the determination of the kinetic parameters of the glow curve. The glow curve responses were explored and the kinetic parameters were analyzed by the WinGCF software, to show the effect of the preheat temperature and heating rate of the reader on Ge-doped fibre irradiated with 18 Gy of 6 MV photons radiation. The effect of TTP parameters was discussed and compared against the commercial fibre and tailored made fibre of 6 mol% Ge-doped of flat and cylindrical shape. The deconvolution of glow peaks and the kinetic parameters were obtained by the WinGCF software. This enables to fit accurately (1.5%

Design and development of a low cost, high current density power supply for streamer free atmospheric pressure DBD plasma generation in air.

PubMed

Jain, Vishal; Visani, Anand; Srinivasan, R; Agarwal, Vivek

2018-03-01

This paper presents a new power supply architecture for generating a uniform dielectric barrier discharge (DBD) plasma in air medium at atmospheric pressure. It is quite a challenge to generate atmospheric pressure uniform glow discharge plasma, especially in air. This is because air plasma needs very high voltage for initiation of discharge. If the high voltage is used along with high current density, it leads to the formation of streamers, which is undesirable for most applications like textile treatment, etc. Researchers have tried to generate high-density plasma using a RF source, nanosecond pulsed DC source, and medium frequency AC source. However, these solutions suffer from low current discharge and low efficiency due to the addition of an external resistor to control the discharge current. Moreover, they are relatively costly and bulky. This paper presents a new power supply configuration which is very compact and generates high average density (∼0.28 W/cm 2 ) uniform glow DBD plasma in air at atmospheric pressure. The efficiency is also higher as no external resistor is required to control the discharge current. An inherent feature of this topology is that it can drive higher current oscillations (∼50 A peak and 2-3 MHz frequency) into the plasma that damp out due to the plasma dissipation only. A newly proposed model has been used with experimental validation in this paper. Simulations and experimental validation of the proposed topology are included. Also, the application of the generated plasma for polymer film treatment is demonstrated.

Design and development of a low cost, high current density power supply for streamer free atmospheric pressure DBD plasma generation in air

NASA Astrophysics Data System (ADS)

Jain, Vishal; Visani, Anand; Srinivasan, R.; Agarwal, Vivek

2018-03-01

This paper presents a new power supply architecture for generating a uniform dielectric barrier discharge (DBD) plasma in air medium at atmospheric pressure. It is quite a challenge to generate atmospheric pressure uniform glow discharge plasma, especially in air. This is because air plasma needs very high voltage for initiation of discharge. If the high voltage is used along with high current density, it leads to the formation of streamers, which is undesirable for most applications like textile treatment, etc. Researchers have tried to generate high-density plasma using a RF source, nanosecond pulsed DC source, and medium frequency AC source. However, these solutions suffer from low current discharge and low efficiency due to the addition of an external resistor to control the discharge current. Moreover, they are relatively costly and bulky. This paper presents a new power supply configuration which is very compact and generates high average density (˜0.28 W/cm2) uniform glow DBD plasma in air at atmospheric pressure. The efficiency is also higher as no external resistor is required to control the discharge current. An inherent feature of this topology is that it can drive higher current oscillations (˜50 A peak and 2-3 MHz frequency) into the plasma that damp out due to the plasma dissipation only. A newly proposed model has been used with experimental validation in this paper. Simulations and experimental validation of the proposed topology are included. Also, the application of the generated plasma for polymer film treatment is demonstrated.

Atmospheric-pressure ionization and fragmentation of peptides by solution-cathode glow discharge† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c6sc02032a Click here for additional data file.

PubMed Central

Schwartz, Andrew J.; Walton, Courtney L.; Williams, Kelsey L.; Hieftje, Gary M.

2016-01-01

Modern “-omics” (e.g., proteomics, glycomics, metabolomics, etc.) analyses rely heavily on electrospray ionization and tandem mass spectrometry to determine the structural identity of target species. Unfortunately, these methods are limited to specialized mass spectrometry instrumentation. Here, a novel approach is described that enables ionization and controlled, tunable fragmentation of peptides at atmospheric pressure. In the new source, a direct-current plasma is sustained between a tapered metal rod and a flowing sample-containing solution. As the liquid stream contacts the electrical discharge, peptides from the solution are volatilized, ionized, and fragmented. At high discharge currents (e.g., 70 mA), electrospray-like spectra are observed, dominated by singly and doubly protonated molecular ions. At lower currents (35 mA), many peptides exhibit extensive fragmentation, with a-, b-, c-, x-, and y-type ion series present as well as complex fragments, such as d-type ions, not previously observed with atmospheric-pressure dissociation. Though the mechanism of fragmentation is currently unclear, observations indicate it could result from the interaction of peptides with gas-phase radicals or ultraviolet radiation generated within the plasma. PMID:28451101

Biomedical evidence of influence of geopathic zones on the human body: scientifically traceable effects and ways of harmonization.

PubMed

Hacker, Gerhard W; Pawlak, Elisabeth; Pauser, Gernot; Tichy, Gottfried; Jell, Hermann; Posch, Gabriele; Kraibacher, Günther; Aigner, Alfred; Hutter, Jörg

2005-12-01

Empiric knowledge of the existence of geopathic zones ('water veins' etc) is probably as old as humankind. It has often been tried to experimentally detect direct influences on the body. However, so far, there have been no publications in accepted biomedical journals. The target of this study was to verify influences of 2 different zones above ground on the human body and to test a device for which pilot studies have indicated a potential harmonizing effect in this context. Using a randomized, non-clinical, double-blinded trial design, 52 persons were tested with a gas discharge visualization (GDV) system whilst staying on 2 zones with or without the Geowave device (Geowave-Research, Salzburg, Austria). The 2 zones investigated had been dowsed by experienced professional dowsers and labeled with black dots in a non-persuasive manner, thereby blindly representing areas of geopathy or more neutral zones. The main analytical parameter was the GDV glow image area (area of glow). Complementary calculated parameters were spatial fractality, corona projections and corona diagrams. In the geopathic zone, the detected areas of glow were statistically significantly smaller than in the more neutral zone. With the Geowave blindly mounted in an adjacent room of the above story, a marked increase of the glow image area was found in both zones. The corona projections showed well-recognizable points of body energy deficits in the geopathic zone, mostly associated with the lymphatic system, the cardiovascular system and the pineal gland, which were -- to a distinctly lesser degree -- also present in the more neutral zone. The device tested yielded compensation or harmonization in both zones in most of the test persons. The significant differences in the physical area of glow parameter, which were also noticed for the complementary parameters analyzed, lead to the conclusion that the 2 different zones within the same room (geopathic vs. more neutral zone) exerted different influences on the human body, which may have caused a geopathic stress phenomenon. As a result, individually different retardation of the immune system and other organs may occur. The device tested in both zones showed harmonizing effects, which may help to compensate some influences of geopathy and possibility also superimposed stressors derived from certain other sources, such as technical electromagnetic fields.

The effect of a miniature argon flow rate on the spectral characteristics of a direct current atmospheric pressure glow micro-discharge between an argon microjet and a small sized flowing liquid cathode

NASA Astrophysics Data System (ADS)

Jamróz, Piotr; Żyrnicki, Wiesław; Pohl, Paweł

2012-07-01

A stable direct current atmospheric pressure glow microdischarge (dc-μAPGD) was generated between a miniature Ar flow microjet and a small sized flowing liquid cathode. The microdischarge was operated in the open to air atmosphere. High energy species, including OH, NH, NO, N2, H, O and Ar were identified in the emission spectra of this microdischarge. Additionally, atomic lines of metals dissolved in water solutions were easily excited. The near cathode and the near anode zones of the microdischarge were investigated as a function of an Ar flow rate up to 300 sccm. The spectroscopic parameters, i.e., the excitation, the vibrational and the rotational temperatures as well as the electron number density, were determined in the near cathode and the near anode regions of the microdischarge. In the near cathode region, the rotational temperatures obtained for OH (2000-2600 K) and N2 bands (1600-1950 K) were significantly lower than the excitation temperatures of Ar (7400 K-7800 K) and H (11 000-15 500 K) atoms. Vibrational temperatures of N2, OH and NO varied from 3400 to 4000 K, from 2900 to 3400 K and from 2700 to 3000 K, respectively. In the near anode region, rotational temperatures of OH (350-1750 K) and N2 (400-1350 K) and excitation temperatures of Ar (5200-5500 K) and H (3600-12 600 K) atoms were lower than those measured in the near cathode region. The effect of the introduction of a liquid sample on the microdischarge radiation and spectroscopic parameters was also investigated in the near cathode zone. The electron number density was calculated from the Stark broadening of the Hβ line and equals to (0.25-1.1) × 1015 cm- 3 and (0.68-1.2) × 1015 cm- 3 in the near cathode and the near anode zones, respectively. The intensity of the Na I emission line and the signal to background ratio (SBR) of this line were investigated in both zones to evaluate the excitation properties of the developed excitation microsource. The limit of detection for Na was determined at the level of 3 ng mL- 1.

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

Study of a contracted glow in low-frequency plasma-jet discharges operating with argon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Minotti, F.; Giuliani, L.; Xaubet, M.

2015-11-15

In this work, we present an experimental and theoretical study of a low frequency, atmospheric plasma-jet discharge in argon. The discharge has the characteristics of a contracted glow with a current channel of submillimeter diameter and a relatively high voltage cathode layer. In order to interpret the measurements, we consider the separate modeling of each region of the discharge: main channel and cathode layer, which must then be properly matched together. The main current channel was modeled, extending a previous work, as similar to an arc in which joule heating is balanced by lateral heat conduction, without thermal equilibrium betweenmore » electrons and heavy species. The cathode layer model, on the other hand, includes the emission of secondary electrons by ion impact and by additional mechanisms, of which we considered emission due to collision of atoms excited at metastable levels, and field-enhanced thermionic emission (Schottky effect). The comparison of model and experiment indicates that the discharge can be effectively sustained in its contracted form by the secondary electrons emitted by collision of excited argon atoms, whereas thermionic emission is by far insufficient to provide the necessary electrons.« less

Thermal mechanism of prepeak formation in Pulsed Glow Discharge

NASA Astrophysics Data System (ADS)

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

2012-10-01

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

Thermoluminescence kinetic features of Lithium Iodide (LiI) single crystal grown by vertical Bridgman technique

NASA Astrophysics Data System (ADS)

Daniel, D. Joseph; Kim, H. J.; Kim, Sunghwan; Khan, Sajid

2017-08-01

Single crystal of pure Lithium Iodide (LiI) has been grown from melt by using the vertical Bridgman technique. Thermoluminescence (TL) Measurements were carried out at 1 K/s following X-ray irradiation. The TL glow curve consists of a dominant peak at (peak-maximum Tm) 393 K and one low temperature peak of weaker intensity at 343 K. The order of kinetics (b), activation energy (E), and the frequency factor (S) for a prominent TL glow peak observed around 393 K for LiI crystals are reported for the first time. The peak shape analysis of the glow peak indicates the kinetics to be of the first order. The value of E is calculated using various standard methods such as initial rise (IR), whole glow peak (WGP), peak shape (PS), computerized glow curve deconvolution (CGCD) and Variable Heating rate (VHR) methods. An average value of 1.06 eV is obtained in this case. In order to validate the obtained parameters, numerically integrated TL glow curve has been generated using experimentally determined kinetic parameters. The effective atomic number (Zeff) for this material was determined and found to be 52. X-ray induced emission spectra of pure LiI single crystal are studied at room temperature and it is found that the sample exhibit sharp emission at 457 nm and broad emission at 650 nm.

Identification of a gamma-irradiated ingredient (garlic powder) in Korean barbeque sauce by thermoluminescence analysis.

PubMed

Ahn, Jae-Jun; Akram, Kashif; Lee, Jeongeun; Kim, Kyong-Su; Kwon, Joong-Ho

2012-04-01

Thermoluminescence (TL) analysis was applied to identify gamma-irradiated garlic powder in Korean barbeque sauce before and after pasteurization (85 °C, 30 min), when blended in different ratios (1%, 3%, and 5%). The sauce sample with nonirradiated garlic powder gave a background glow curve. However, the sample blended with irradiated ingredient (1 and 10 kGy) showed typical TL glow curves at temperatures of 150 to 200 °C. The identification properties of sauce samples were more influenced by blending ratios than by irradiation doses, showing that 3% and 5% added samples produced glow curves at 150 to 250 °C. After pasteurization of the samples containing the irradiated ingredient, TL glow intensity decreased but did not change its shape or temperature range. As a result, the pasteurization of Barbeque sauces containing irradiated ingredients had reduced TL glow intensity, but the shape and temperature range of glow curve were still able to provide information required for confirming irradiation treatment. To monitor the irradiated food in international market, thermoluminescence (TL) analysis is considered most promising identification technique because of its sensitivity and long-term stability. In this study the applicability of TL analysis to detect an irradiated ingredient (garlic powder) added in low quantity to a food matrix (sauce) was investigated. The effect of processing (pasteurization) on TL results was also evaluated. © 2012 Institute of Food Technologists®

Accounting protesting and warm glow bidding in Contingent Valuation surveys considering the management of environmental goods--an empirical case study assessing the value of protecting a Natura 2000 wetland area in Greece.

PubMed

Grammatikopoulou, Ioanna; Olsen, Søren Bøye

2013-11-30

Based on a Contingent Valuation survey aiming to reveal the willingness to pay (WTP) for conservation of a wetland area in Greece, we show how protest and warm glow motives can be taken into account when modeling WTP. In a sample of more than 300 respondents, we find that 54% of the positive bids are rooted to some extent in warm glow reasoning while 29% of the zero bids can be classified as expressions of protest rather than preferences. In previous studies, warm glow bidders are only rarely identified while protesters are typically identified and excluded from further analysis. We test for selection bias associated with simple removal of both protesters and warm glow bidders in our data. Our findings show that removal of warm glow bidders does not significantly distort WTP whereas we find strong evidence of selection bias associated with removal of protesters. We show how to correct for such selection bias by using a sample selection model. In our empirical sample, using the typical approach of removing protesters from the analysis, the value of protecting the wetland is significantly underestimated by as much as 46% unless correcting for selection bias. Copyright © 2013 Elsevier Ltd. All rights reserved.

The Drama of Starbirth - new-born stars wreak havoc in their nursery

NASA Astrophysics Data System (ADS)

2011-03-01

A new image from ESO's Very Large Telescope gives a close-up view of the dramatic effects new-born stars have on the gas and dust from which they formed. Although the stars themselves are not visible, material they have ejected is colliding with the surrounding gas and dust clouds and creating a surreal landscape of glowing arcs, blobs and streaks. The star-forming region NGC 6729 is part of one of the closest stellar nurseries to the Earth and hence one of the best studied. This new image from ESO's Very Large Telescope gives a close-up view of a section of this strange and fascinating region (a wide-field view is available here: eso1027). The data were selected from the ESO archive by Sergey Stepanenko as part of the Hidden Treasures competition [1]. Sergey's picture of NGC 6729 was ranked third in the competition. Stars form deep within molecular clouds and the earliest stages of their development cannot be seen in visible-light telescopes because of obscuration by dust. In this image there are very young stars at the upper left of the picture. Although they cannot be seen directly, the havoc that they have wreaked on their surroundings dominates the picture. High-speed jets of material that travel away from the baby stars at velocities as high as one million kilometres per hour are slamming into the surrounding gas and creating shock waves. These shocks cause the gas to shine and create the strangely coloured glowing arcs and blobs known as Herbig-Haro objects [2]. In this view the Herbig-Haro objects form two lines marking out the probable directions of ejected material. One stretches from the upper left to the lower centre, ending in the bright, circular group of glowing blobs and arcs at the lower centre. The other starts near the left upper edge of the picture and extends towards the centre right. The peculiar scimitar-shaped bright feature at the upper left is probably mostly due to starlight being reflected from dust and is not a Herbig-Haro object. This enhanced-colour picture [3] was created from images taken using the FORS1 instrument on ESO's Very Large Telescope. Images were taken through two different filters that isolate the light coming from glowing hydrogen (shown as orange) and glowing ionised sulphur (shown as blue). The different colours in different parts of this violent star formation region reflect different conditions - for example where ionised sulphur is glowing brightly (blue features) the velocities of the colliding material are relatively low - and help astronomers to unravel what is going on in this dramatic scene. Notes [1] 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. [2] The astronomers George Herbig and Guillermo Haro were not the first to see one of the objects that now bear their names, but they were the first to study the spectra of these strange objects in detail. They realised that they were not just clumps of gas and dust that reflected light, or glowed under the influence of the ultraviolet light from young stars, but were a new class of objects associated with ejected material in star formation regions. [3] Both the ionised sulphur and hydrogen atoms in this nebula emit red light. To differentiate between them in this image the sulphur emission has been coloured blue. 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 operates the Very Large Telescope, the world's most advanced visible-light astronomical observatory and VISTA, the world's largest survey telescope. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning a 42-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become "the world's biggest eye on the sky".

Investigation of thermoluminescence and kinetic parameters of CaMgB{sub 2}O{sub 5}: Dy{sup 3+} nanophosphor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Manhas, M.; Kumar, Vinay, E-mail: vinaykumar@smvdu.ac.in; Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein ZA9300

2016-05-06

In this paper, thermoluminescence (TL) properties of Dy{sup 3+} (1.5 mol %) doped CaMgB{sub 2}O{sub 5} nanophosphor after being exposed to ultraviolet (UV) radiations (λ=254nm) were investigated. In UV exposed samples, the thermoluminescence glow curve consists of a broad glow peak located at 380 K with a small shoulder at 507 K. A shift in glow peak temperature from 367 K to 380 K after the UV exposure for 80 min was observed, which clearly shows that glow peaks follow the second order kinetics. The TL intensity of the peaks increases with an increase in the exposure time of UV rays (10-180 min). The TL Anal programmore » was used to analyze the glow curve. The kinetic parameters such as activation energy (E), the frequency factor (s) and the order of kinetics (b) were calculated for CaMgB{sub 2}O{sub 5}: Dy{sup 3+} nanophosphors.« less

Spent fuel burnup estimation by Cerenkov glow intensity measurement

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuribara, Masayuki

1994-10-01

The Cerenkov glow images from irradiated fuel assemblies of boiling-water reactors (BWR) and pressurized-water reactors (PWR) are generally used for inspections. For this purpose, a new UV-I.I. CVD (ultra-violet light image intensifier Cerenkov viewing device), has been developed. This new device can measure the intensity of the Cerenkov glow from a spent fuel assembly, thus making it possible to estimate the burnup of the fuel assembly by comparing the Cerenkov glow intensity to the reference intensity. The experiment was carried out on BWR spent fuel assemblies and the results show that burnups are estimated within 20% accuracy compared to themore » declared burnups for the tested spent fuel assemblies for cooling times ranging from 900--2.000 d.« less

Correlation between thermoluminescence glow curve and emission spectra of gamma ray irradiated LaAlO3

NASA Astrophysics Data System (ADS)

Shivaramu, N. J.; Lakshminarasappa, B. N.; Nagabhushana, K. R.; Coetsee, E.; Swart, H. C.

2018-04-01

Lanthanum aluminate (LaAlO3) is synthesized by solution combustion method and the resultant powder is annealed at 900°C for 2 hours. X-ray diffraction (XRD) pattern confirms the rhombohedral structure LaAlO3 with space group R3 ¯c. γ-irradiated nanocrystalline lanthanum aluminate gives two prominent TL glow with peaks at 399 and 639 K and weak one at 547 K. TL intensity at 399 K increases up to 9.0 kGy and then decreases with increasing γ-dose. TL emission shows at 650 nm and 736 nm is attributed to the charge transfer from oxygen to metal ions. The glow curves are analyzed and the trap parameters are calculated by glow curve deconvoluted technique.

A high resolution ultraviolet Shuttle glow spectrograph

NASA Technical Reports Server (NTRS)

Carruthers, George R.

1993-01-01

The High Resolution Shuttle Glow Spectrograph-B (HRSGS-B) is a small payload being developed by the Naval Research Laboratory. It is intended for study of shuttle surface glow in the 180-400 nm near- and middle-ultraviolet wavelength range, with a spectral resolution of 0.2 nm. It will search for, among other possible features, the band systems of excited NO which result from surface-catalyzed combination of N and O. It may also detect O2 Hertzberg bands and N2 Vegard-Kaplan bands resulting from surface recombination. This wavelength range also includes possible N2+ and OH emissions. The HRSGS-B will be housed in a Get Away Special canister, mounted in the shuttle orbiter payload bay, and will observe the glow on the tail of the orbiter.

Wire-chamber radiation detector with discharge control

DOEpatents

Perez-Mendez, V.; Mulera, T.A.

1982-03-29

A wire chamber; radiation detector has spaced apart parallel electrodes and grids defining an ignition region in which charged particles or other ionizing radiations initiate brief localized avalanche discharges and defining an adjacent memory region in which sustained glow discharges are initiated by the primary discharges. Conductors of the grids at each side of the memory section extend in orthogonal directions enabling readout of the X-Y coordinates of locations at which charged particles were detected by sequentially transmitting pulses to the conductors of one grid while detecting transmissions of the pulses to the orthogonal conductors of the other grid through glow discharges. One of the grids bounding the memory region is defined by an array of conductive elements each of which is connected to the associated readout conductor through a separate resistance. The wire chamber avoids ambiguities and imprecisions in the readout of coordinates when large numbers of simultaneous or; near simultaneous charged particles have been detected. Down time between detection periods and the generation of radio frequency noise are also reduced.

Method for synthesizing ultrafine powder materials

DOEpatents

Buss, Richard J.; Ho, Pauline

1988-01-01

A method for synthesizing ultrafine powder materials, for example, ceramic and metal powders, comprises admitting gaseous reactants from which the powder material is to be formed into a vacuum reaction chamber maintained at a pressure less than atmospheric and at a temperature less than about 400.degree. K. (127.degree.C.). The gaseous reactants are directed through a glow discharge provided in the vacuum reaction chamber to form the ultrafine powder material.

A fading-based method for checking the presence of closely overlapping peaks in thermoluminescent (TL) materials

NASA Astrophysics Data System (ADS)

Furetta, C.

The paper describes a method, based on fading experiment, for determining the presence of a complex structure in the thermoluminescent glow curve emission from herbs, e.g. oregano and nopal. Because of the polymineral content of the inorganic part of these herbs, the emitted glow curve is the result of several overlapping glow peaks, each one corresponding to another mineral. The initial rise method is also used for determining the activation energy of each component.

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

DOEpatents

Hunter, Scott R.; Christophorou, Loucas G.

1990-01-01

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

System OptimizatIon of the Glow Discharge Optical Spectroscopy Technique Used for Impurity Profiling of ION Implanted Gallium Arsenide.

DTIC Science & Technology

1980-12-01

AFIT/GEO/EE/80D-1 I -’ SYSTEM OPTIMIZATION OF THE GLOW DISCHARGE OPTICAL SPECTROSCOPY TECHNIQUE USED FOR IMPURITY PROFILING OF ION IMPLANTED GALLIUM ...EE/80D-1 (\\) SYSTEM OPTIMIZATION OF THE GLOW DISCHARGE OPTICAL SPECTROSCOPY TECHNIQUE USED FOR IMPURITY PROFILING OF ION IMPLANTED GALLIUM ARSENIDE...semiconductors, specifically annealed and unan- nealed ion implanted gallium arsenide (GaAs). Methods to improve the sensitivity of the GDOS system have

The Effects of Lamp Spectral Distribution on Sky Glow over Observatories

DTIC Science & Technology

2015-01-01

overhead sky glow as a function of distance up to 300 km, from a variety of lamp types, including common gas discharge lamps and several types of LED...distance up to 300 km, from a variety of lamp types, in- cluding common gas discharge lamps and several types of LED lamps . We conclude for both...MAR 2015 2. REPORT TYPE 3. DATES COVERED 00-00-2015 to 00-00-2015 4. TITLE AND SUBTITLE The Effects of Lamp Spectral Distribution on Sky Glow

Numerical investigation on the dynamics and evolution mechanisms of multiple-current-pulse behavior in homogeneous helium dielectric-barrier discharges at atmospheric pressure

NASA Astrophysics Data System (ADS)

Zhang, Yuhui; Ning, Wenjun; Dai, Dong

2018-03-01

A systematic investigation on the dynamics and evolution mechanisms of multiple-current-pulse (MCP) behavior in homogeneous dielectric barrier discharge (HDBD) is carried out via fluid modelling. Inspecting the simulation results, two typical discharge regimes, namely the MCP-Townsend regime and MCP-glow regime, are found prevailing in MCP discharges, each with distinctive electrical and dynamic properties. Moreover, the evolution of MCP behavior with external parameters altering are illustrated and explicitly discussed. It is revealed that the discharge undergoes some different stages as external parameters vary, and the discharge in each stage follows a series of distinctive pattern in morphological characteristics and evolution trends. Among those stages, the pulse number per half cycle is perceived to observe non-monotonic variations with applied voltage amplitude (Vam) and gap width (dg) increasing, and a merging effect among pulses, mainly induced by the enhanced contribution of sinusoidal component to the total current, is considered responsible for such phenomenon. The variation of incipient discharge peak phase (Φpm) is dominated by the value of Vam as well as the proportion of total applied voltage that drops across the gas gap. Moreover, an abnormal, dramatic elevation in Jpm with dg increasing is observed, which could be evinced by the strengthened glow discharge structure and therefore enhanced space charge effect.

Masking Out Galaxies

NASA Image and Video Library

2014-11-06

This graphic illustrates how the Cosmic Infrared Background Experiment, or CIBER, team measures a diffuse glow of infrared light filling the spaces between galaxies. The glow does not come from any known stars and galaxies.

Focused beams of fast neutral atoms in glow discharge plasma

NASA Astrophysics Data System (ADS)

Grigoriev, S. N.; Melnik, Yu. A.; Metel, A. S.; Volosova, M. A.

2017-06-01

Glow discharge with electrostatic confinement of electrons in a vacuum chamber allows plasma processing of conductive products in a wide pressure range of p = 0.01 - 5 Pa. To assist processing of a small dielectric product with a concentrated on its surface beam of fast neutral atoms, which do not cause charge effects, ions from the discharge plasma are accelerated towards the product and transformed into fast atoms. The beam is produced using a negatively biased cylindrical or a spherical grid immersed in the plasma. Ions accelerated by the grid turn into fast neutral atoms at p > 0.1 Pa due to charge exchange collisions with gas atoms in the space charge sheaths adjoining the grid. The atoms form a diverging neutral beam and a converging beam propagating from the grid in opposite directions. The beam propagating from the concave surface of a 0.24-m-wide cylindrical grid is focused on a target within a 10-mm-wide stripe, and the beam from the 0.24-m-diameter spherical grid is focused within a 10-mm-diameter circle. At the bias voltage U = 5 kV and p ˜ 0.1 Pa, the energy of fast argon atoms is distributed continuously from zero to eU ˜ 5 keV. The pressure increase to 1 Pa results in the tenfold growth of their equivalent current and a decrease in the mean energy by an order of magnitude, which substantially raises the efficiency of material etching. Sharpening by the beam of ceramic knife-blades proved that the new method for the generation of concentrated fast atom beams can be effectively used for the processing of dielectric materials in vacuum.

Two-dimensional simulation of argon dielectric barrier discharge excited by a Gaussian voltage at atmospheric pressure

NASA Astrophysics Data System (ADS)

Xu, Yonggang; Wang, Jing; Li, Jing; Lei, Bingying; Tang, Jie; Wang, Yishan; Li, Yongfang; Zhao, Wei; Duan, Yixiang

2017-04-01

A two-dimensional self-consistent fluid model was employed to investigate the spatiotemporal characteristics of discharges in atmospheric pressure argon (Ar) dielectric barrier discharge driven by a Gaussian voltage. The simulation results show that a discharge with multiple current pulses occurs each half-cycle in the gas gap. A transition from the Townsend mode to the glow mode is observed with the increasing applied voltage each half-cycle at a lower driving frequency (7.5 kHz). It is also found that the glow mode survives all the discharge phases at a higher driving frequency (12.5 kHz and 40 kHz). The change in the discharge mode with the driving frequency mainly lies in the fact that a lot of charged particles created in the discharge gap have no enough time to drift and diffuse around, and then these particles are assembled in the discharge space at higher frequency. Additionally, the spatial distributions of the electron density indicate that a center-advantage discharge is ignited at the driving frequencies of interest, resulting in the radial non-uniformity of discharge because of the edge effects. However, this overall non-uniformity is weakened with the driving frequency increased to 40 kHz, at which concentric ring patterns are observed. These distinct behaviors are mainly attributed to the fact that many charged particles generated are trapped in the gas gap and then accumulated to make the extension along the radial direction due to the charged particles transport and diffusion, and that the effective overlapping of a large number of avalanches induced by the increased "seed" electron density with the driving frequency. Meanwhile, the surface charged particles accumulated on the dielectric barriers are also shown to play a role in the formation of the discharge structure.

Computerized glow curve deconvolution of thermoluminescent emission from polyminerals of Jamaica Mexican flower

NASA Astrophysics Data System (ADS)

Favalli, A.; Furetta, C.; Zaragoza, E. Cruz; Reyes, A.

The aim of this work is to study the main thermoluminescence (TL) characteristics of the inorganic polyminerals extracted from dehydrated Jamaica flower or roselle (Hibiscus sabdariffa L.) belonging to Malvaceae family of Mexican origin. TL emission properties of the polymineral fraction in powder were studied using the initial rise (IR) method. The complex structure and kinetic parameters of the glow curves have been analysed accurately using the computerized glow curve deconvolution (CGCD) assuming an exponential distribution of trapping levels. The extension of the IR method to the case of a continuous and exponential distribution of traps is reported, such as the derivation of the TL glow curve deconvolution functions for continuous trap distribution. CGCD is performed both in the case of frequency factor, s, temperature independent, and in the case with the s function of temperature.

Simulation of stationary glow patterns in dielectric barrier discharges at atmospheric pressure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Fucheng, E-mail: hdlfc@hbu.cn; He, Yafeng; Dong, Lifang

2014-12-15

Self-organized stationary patterns in dielectric barrier discharges operating in glow regime at atmospheric pressure are investigated by a self-consistent two-dimensional fluid model. The simulation results show that two different modes, namely, the diffuse mode and the static patterned mode, can be formed in different ranges of the driving frequency. The discharge operates in Townsend regime in the diffuse mode, while it operates in a glow regime inside the filaments and in a Townsend regime outside the filaments in the stable pattered mode. The forming process of the stationary filaments can be divided into three stages, namely, destabilizing stage, self-assembling stage,more » and stable stage. The space charge associated with residual electron density and surface charge is responsible for the formation of these stationary glow patterns.« less

ESCA Study of Poly (Vinylidene Fluoride) Tetrafluoroethylene - Ethylene Copolymer and Polyethylene Exposed to Atomic Oxygen

NASA Technical Reports Server (NTRS)

Golub, Morton A.; Cormia, Robert D.

1989-01-01

The ESCA (electron spectroscopy for chemical analysis) spectra of films of poly(vinylidene fluoride) (PVDF), tetrafluoroethylene-ethylene copolymer (TFE/ET) and polyethylene (PE) exposed to atomic oxygen (O(P-3)), in or out of the glow of a radio-frequency O2 plasma, were compared. ESCA spectra of PE films exposed to (O(P-3)) in low Earth orbit (LEO) on the STS-8 Space Shuttle were also examined. Apart from O(P-3)-induced surface recession (etching), the various polymer films exhibited surface oxidation, which proceeded towards equilibrium saturation oxygen levels. The maximum surface oxygen uptakes for in-glow or out-of-glow exposures were in the order: PE greater than TFE/ET greater than PVDF; for PE itself, the oxygen uptakes were in the order: in glow greater than out of glow greater than LEO. Given prior ESCA data on poly(vinyl fluoride) and polytetrafluoroethylene films exposed to O(P-3), the extent of surface oxidation is seen to decrease regularly with increase in fluorine substitution in a family of ethylene-type polymers. (Keywords: ESCA; poly(vinylidene fluoride); tetrafluoroethylene ethylene copolymer; polyethylene; atomic oxygen; radio-frequency oxygen plasma; low Earth orbit)

The nonlocal electron kinetics for a low-pressure glow discharge dusty plasma

NASA Astrophysics Data System (ADS)

Liang, Yonggan; Wang, Ying; Li, Hui; Tian, Ruihuan; Yuan, Chengxun; Kudryavtsev, A. A.; Rabadanov, K. M.; Wu, Jian; Zhou, Zhongxiang; Tian, Hao

2018-05-01

The nonlocal electron kinetic model based on the Boltzmann equation is developed in low-pressure argon glow discharge dusty plasmas. The additional electron-dust elastic and inelastic collision processes are considered when solving the kinetic equation numerically. The orbital motion limited theory and collision enhanced collection approximation are employed to calculate the dust surface potential. The electron energy distribution function (EEDF), effective electron temperature Teff, and dust surface potential are investigated under different plasma and dust conditions by solving the Boltzmann and the dust charging current balance equations self-consistently. A comparison of the calculation results obtained from nonlocal and local kinetic models is made. It is shown that the appearance of dust particles leads to a deviation of the EEDF from its original profile for both nonlocal and local kinetic models. With the increase in dust density and size, the effective electron temperature and dust surface potential decrease due to the high-energy electron loss on the dust surface. Meanwhile, the nonlocal and local results differ much from each other under the same calculation condition. It is concluded that, for low-pressure (PR ≤ 1 cm*Torr) glow discharge dusty plasmas, the existence of dust particles will amplify the difference of local and nonlocal EEDFs, which makes the local kinetic model more improper to determine the main parameters of the positive column. The nonlocal kinetic model should be used for the calculation of the EEDFs and dusty plasma parameters.

Effect of pulsed discharge on the ignition of pulse modulated radio frequency glow discharge at atmospheric pressure

NASA Astrophysics Data System (ADS)

Qiu, Shenjie; Guo, Ying; Han, Qianhan; Bao, Yun; Zhang, Jing; Shi, J. J.

2018-01-01

A pulsed discharge is introduced between two sequential pulse-modulated radio frequency glow discharges in atmospheric helium. The dependence of radio frequency discharge ignition on pulsed discharge intensity is investigated experimentally with the pulse voltage amplitudes of 650, 850, and 1250 V. The discharge characteristics and dynamics are studied in terms of voltage and current waveforms, and spatial-temporal evolution of optical emission. With the elevated pulsed discharge intensity of two orders of magnitude, the ignition of radio frequency discharge is enhanced by reducing the ignition time and achieving the stable operation with a double-hump spatial profile. The ignition time of radio frequency discharge is estimated to be 2.0 μs, 1.5 μs, and 1.0 μs with the pulse voltage amplitudes of 650, 850, and 1250 V, respectively, which is also demonstrated by the spatial-temporal evolution of optical emission at 706 and 777 nm.

Achieving ultrahigh vacuum in an unbaked chamber with glow discharge conditioning

NASA Astrophysics Data System (ADS)

Khan, Ziauddin; Semwal, Pratibha; Dhanani, Kalpesh R.; Raval, Dilip C.; Pradhan, Subrata

2017-01-01

Glow discharge conditioning (GDC) has long been accepted as one of the basic wall conditioning techniques for achieving ultrahigh vacuum in an unbaked chamber. As a part of this fundamental experimental study, a test chamber has been fabricated from stainless steel 304 L with its inner surface electropolished on which a detailed investigation has been carried out. Both helium and hydrogen gases have been employed as discharge cleaning medium. The discharge cleaning was carried out at 0.1 A / m 2 current density with working pressure maintained at 1.0 × 10 -2 mbar. It was experimentally observed that the pump-down time to attain the base pressure 10 -8 mbar was reduced by 62% compared to the unbaked chamber being pumped to this ultimate vacuum. The results were similar irrespective of whether the discharge cleaning medium is either hydrogen or helium. It was also experimentally established that a better ultimate vacuum could be achieved as compared to theoretically calculated ultimate vacuum with the help of discharge cleaning.

Identification of low amount of irradiated spices (red pepper, garlic, ginger powder) with luminescence analysis

NASA Astrophysics Data System (ADS)

Kim, Byeong-Keun; Akram, Kashif; Kim, Cheong-Tae; Kang, Na-Roo; Lee, Jin-Won; Ryang, Jun-Hwan; Kwon, Joong-Ho

2012-08-01

For the identification of irradiated food, current analysis methods have limitations regarding presence and stability of radiation-induced markers. In this study, different spice blends with small quantity of different irradiated (0, 1 and 10 kGy) spice powders, such as red pepper, garlic or ginger, were investigated using PSL and TL techniques. In PSL-based screening analysis, the spice blends containing 10% of irradiated materials (1 or 10 kGy) were determined as intermediate or positive. In TL results, the blends containing 1% of 1 or 10 kGy-irradiated spices showed the typical TL glow curves that could be interpreted as positive. The blends with irradiated garlic powder provided more good results where identification was possible at 0.5% mixing of irradiated sample. However, the TL ratios of all spice blends were <0.1 and only TL glow curve shape and intensity may be used to discriminate the samples having irradiated component.

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

DOEpatents

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

1988-04-27

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

Removal of a glowing spot from an image tube using laser radiation.

NASA Technical Reports Server (NTRS)

Gurski, T. R.

1972-01-01

A troublesome problem with the Kron electronograph has been the presence of a white glowing spot on the glass wall of the tube adjacent to the focus electrode. The procedure followed to eliminate the spot was to operate in the dark and apply voltage only to the focused electrode. Ruby laser radiation was unfocused, and its position was shifted on the electrode between laser shots until an effect was observed. This technique for removing the glowing spot should be applicable to other electronic image tubes.

Io Eclipse Montage

NASA Technical Reports Server (NTRS)

2007-01-01

New Horizons took this montage of images of Jupiter's volcanic moon Io, glowing in the dark of Jupiter's shadow, as the Pluto-bound spacecraft sped through the Jupiter system on Feb. 27, 2007.

(A): In this picture from the Long-Range Reconnaissance Imager (LORRI), dark blotches and straight lines are artifacts. The brightest spots (including the volcanoes Pele [P] and East Girru [EG]) are incandescent lava from active volcanoes. The more diffuse glows, and the many faint spots, are from gas in the plumes and atmosphere, glowing due to bombardment by plasma in Jupiter's magnetosphere, in a display similar to the Earth's aurorae. (B): The same image with a latitude/longitude grid, showing that the cluster of faint spots is centered near longitude 0 degrees, the point on Io that faces Jupiter. The image also shows the locations of the plumes seen in sunlit images (indicated by red diamonds), which glow with auroral emission in eclipse. (C): Simulated sunlit view of Io with the same geometry, based on sunlit LORRI images. (D): A combination of the sunlit image (in cyan) and the eclipse image (in red), showing that all point-like glows in the eclipse image arise from dark volcanoes in the eclipse image. (E): This infrared image, at a wavelength of 2.3 microns, obtained by New Horizons Linear Etalon Spectral Imaging Array (LEISA) an hour after the LORRI image, showing thermal emission from active volcanoes. Elongation of the hot spots is an artifact. (F): Combined visible albedo (cyan) and LEISA thermal emission (red) image, showing the sources of the volcanic emission. That most of the faint point-like glows near longitude zero, seen in visible light in images A, B, and D, do not appear in the infrared view of volcanic heat radiation, is one reason scientists believe that these glows are due to auroral emission, not heat radiation.

This image appears in the Oct. 12, 2007, issue of Science magazine, in a paper by John Spencer, et al.

Dawn Blue Glow Artist Concept

NASA Image and Video Library

2015-03-02

This artist concept shows NASA Dawn spacecraft arriving at the dwarf planet Ceres. Dawn travels through space using a technology called ion propulsion, with ions glowing with blue light are accelerated out of an engine, giving the spacecraft thrust.

In the Blackest Night, a Green Ring Nebula

NASA Image and Video Library

2011-06-15

This glowing emerald nebula seen by NASA Spitzer Space Telescope is named RCW 120; this region of hot gas and glowing dust can be found in the murky clouds encircled by the tail of the constellation Scorpius.

Thermoluminescence glow-curve characteristics of LiF phosphors at high doses of gamma radiation

NASA Astrophysics Data System (ADS)

Benny, P. G.; Khader, S. A.; Sarma, K. S. S.

2013-05-01

High doses of ionising radiation are becoming increasingly common for radiation-processing applications of various medical, agricultural and polymer products using gamma and electron beams. The objective of this work was to study thermoluminescence (TL) glow-curve characteristics of commonly used commercial LiF TL phosphors at high doses of radiation with a view to use them in dosimetry of radiation-processing applications. The TL properties of TLD 100 and 700 phosphors, procured from the Thermo-Scientific (previously Harshaw) company, have been studied in the dose range of 1-60 kGy. The shift in glow peaks was observed in this dose range. Integral TL responses of TLD 100 and TLD 700 were found to decrease as a linear function of dose in the range of 5-50 kGy. The paper describes initial results related to the glow-curve characteristics of these phosphors.

Apocenter Glow in Eccentric Debris Disks: Implications for Fomalhaut and Epsilon Eridani

NASA Technical Reports Server (NTRS)

Pan, Margaret; Nesvold, Erika R.; Kuchner, Marc J.

2016-01-01

Debris disks often take the form of eccentric rings with azimuthal asymmetries in surface brightness. Such disks are often described as showing pericenter glow, an enhancement of the disk brightness in regions nearest the central star. At long wavelengths, however, the disk apocenters should appear brighter than their pericenters: in the long-wavelength limit, we find that the apocenter pericenter flux ratio scales as 1 + e for disk eccentricity e. We produce new models of this apocenter glow to explore its causes and wavelength dependence and study its potential as a probe of dust grain properties. Based on our models, we argue that several far-infrared and (sub)millimeter images of the Fomalhaut and Epsilon Eridani debris rings obtained with Herschel, JCMT, SHARC II, ALMA, and ATCA should be reinterpreted as suggestions or examples of apocenter glow. This reinterpretation yields new constraints on the disks dust grain properties and size distributions.

Extension of spatiotemporal chaos in glow discharge-semiconductor systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akhmet, Marat, E-mail: marat@metu.edu.tr; Fen, Mehmet Onur; Rafatov, Ismail

2014-12-15

Generation of chaos in response systems is discovered numerically through specially designed unidirectional coupling of two glow discharge-semiconductor systems. By utilizing the auxiliary system approach, [H. D. I. Abarbanel, N. F. Rulkov, and M. M. Sushchik, Phys. Rev. E 53, 4528–4535 (1996)] it is verified that the phenomenon is not a chaos synchronization. Simulations demonstrate various aspects of the chaos appearance in both drive and response systems. Chaotic control is through the external circuit equation and governs the electrical potential on the boundary. The expandability of the theory to collectives of glow discharge systems is discussed, and this increases themore » potential of applications of the results. Moreover, the research completes the previous discussion of the chaos appearance in a glow discharge-semiconductor system [D. D. Šijačić U. Ebert, and I. Rafatov, Phys. Rev. E 70, 056220 (2004).].« less

Extension of spatiotemporal chaos in glow discharge-semiconductor systems.

PubMed

Akhmet, Marat; Rafatov, Ismail; Fen, Mehmet Onur

2014-12-01

Generation of chaos in response systems is discovered numerically through specially designed unidirectional coupling of two glow discharge-semiconductor systems. By utilizing the auxiliary system approach, [H. D. I. Abarbanel, N. F. Rulkov, and M. M. Sushchik, Phys. Rev. E 53, 4528-4535 (1996)] it is verified that the phenomenon is not a chaos synchronization. Simulations demonstrate various aspects of the chaos appearance in both drive and response systems. Chaotic control is through the external circuit equation and governs the electrical potential on the boundary. The expandability of the theory to collectives of glow discharge systems is discussed, and this increases the potential of applications of the results. Moreover, the research completes the previous discussion of the chaos appearance in a glow discharge-semiconductor system [D. D. Šijačić U. Ebert, and I. Rafatov, Phys. Rev. E 70, 056220 (2004).].

Preliminary chaotic model of snapover on high voltage solar cells

NASA Technical Reports Server (NTRS)

Mackey, Willie R.

1995-01-01

High voltage power systems in space will interact with the space plasma in a variety of ways. One of these, snapover, is characterized by sudden enlargement of the current collection area across normally insulating surfaces generating enhanced electron current collection. Power drain on solar array power systems results from this enhanced current collection. Optical observations of the snapover phenomena in the laboratory indicates a functional relation between glow area and bia potential as a consequence of the fold/cusp bifurcation in chaos theory. Successful characterizations of snapover as a chaotic phenomena may provide a means of snapover prevention and control through chaotic synchronization.

Characterization of Light at Night Data from Select SkyGlowNet Nodes

NASA Astrophysics Data System (ADS)

Flurchick, K. M.; Deal, S.; Foster, C.

2013-05-01

Internet-enabled sky brightness meters (iSBMs) that continuously record and log sky brightness at the zenith have been installed at the prototype nodes of a network called SkyGlowNet. Also logged are time and weather information. These data are polled at a user-defined frequency, typically about every 45 seconds. Although the SkyGlowNetdata are used for various professional scientific studies, they are also useful for independent student research projects. In this case, the data are uploaded to the SkyGlowNetwebsite, initially to a proprietary area where the data for each institution are embargoed for one or two semesters as students conduct research projects with their data. When released from embargo, the data are moved to another area where they can be accessed by all SkyGlowNet participants. In this paper, we describe a student project in which the data collected at two SkyGlowNet sites are characterized. The data streams are parsed into homogenous segments and statistical tools are employed to describe variations observed in the data values. We demonstrate how to differentiate between natural phenomena and the effects of artificial lighting on the brightness of the night sky. In our poster we show how these effects compare between sites as separate as Arizona and North Carolina. We also have experimented with the development of statistical metrics that are used to help categorize sky brightness on select nights, and can nearly automatically provide a characterization of the quality of the night sky for astronomical purposes.

Emission characteristics of 6.78-MHz radio-frequency glow discharge plasma in a pulsed mode

NASA Astrophysics Data System (ADS)

Zhang, Xinyue; Wagatsuma, Kazuaki

2017-07-01

This paper investigated Boltzmann plots for both atomic and ionic emission lines of iron in an argon glow discharge plasma driven by 6.78-MHz radio-frequency (RF) voltage in a pulsed operation, in order to discuss how the excitation/ionization process was affected by the pulsation. For this purpose, a pulse frequency as well as a duty ratio of the pulsed RF voltage was selected as the experimenter parameters. A Grimm-style radiation source was employed at a forward RF power of 70 W and at an argon pressures of 670 Pa. The Boltzmann plot for low-lying excited levels of iron atom was on a linear relationship, which was probably attributed to thermal collisions with ultimate electrons in the negative glow region; in this case, the excitation temperature was obtained in a narrow range of 3300-3400 K, which was hardly affected by the duty ratio as well as the pulse frequency of the pulsed RF glow discharge plasma. This observation suggested that the RF plasma could be supported by a self-stabilized negative glow region, where the kinetic energy distribution of the electrons would be changed to a lesser extent. Additional non-thermal excitation processes, such as a Penning-type collision and a charge-transfer collision, led to deviations (overpopulation) of particular energy levels of iron atom or iron ion from the normal Boltzmann distribution. However, their contributions to the overall excitation/ionization were not altered so greatly, when the pulse frequency or the duty ratio was varied in the pulsed RF glow discharge plasma.

Microplasma-based flowing atmospheric-pressure afterglow (FAPA) source for ambient desorption-ionization mass spectrometry.

PubMed

Zeiri, Offer M; Storey, Andrew P; Ray, Steven J; Hieftje, Gary M

2017-02-01

A new direct-current microplasma-based flowing atmospheric pressure afterglow (FAPA) source was developed for use in ambient desorption-ionization mass spectrometry. The annular-shaped microplasma is formed in helium between two concentric stainless-steel capillaries that are separated by an alumina tube. Current-voltage characterization of the source shows that this version of the FAPA operates in the normal glow-discharge regime. A glass surface placed in the path of the helium afterglow reaches temperatures of up to approximately 400 °C; the temperature varies with distance from the source and helium flow rate through the source. Solid, liquid, and vapor samples were examined by means of a time-of-flight mass spectrometer. Results suggest that ionization occurs mainly through protonation, with only a small amount of fragmentation and adduct formation. The mass range of the source was shown to extend up to at least m/z 2722 for singly charged species. Limits of detection for several small organic molecules were in the sub-picomole range. Examination of competitive ionization revealed that signal suppression occurs only at high (mM) concentrations of competing substances. Copyright © 2016 Elsevier B.V. All rights reserved.

Advances and directions of ion nitriding/carburizing

NASA Technical Reports Server (NTRS)

Spalvins, Talivaldis

1989-01-01

Ion nitriding and carburizing are plasma activated thermodynamic processes for the production of case hardened surface layers not only for ferrous materials, but also for an increasing number of nonferrous metals. When the treatment variables are properly controlled, the use of nitrogenous or carbonaceous glow discharge medium offers great flexibility in tailoring surface/near-surface properties independently of the bulk properties. The ion nitriding process has reached a high level of maturity and has gained wide industrial acceptance, while the more recently introduced ion carburizing process is rapidly gaining industrial acceptance. The current status of plasma mass transfer mechanisms into the surface regarding the formation of compound and diffusion layers in ion nitriding and carbon build-up ion carburizing is reviewed. In addition, the recent developments in design and construction of advanced equipment for obtaining optimized and controlled case/core properties is summarized. Also, new developments and trends such as duplex plasma treatments and alternatives to dc diode nitriding are highlighted.

Phase formation in selected surface-roughened plasma-nitrided 304 austenite stainless steel.

PubMed

Singh, Gajendra Prasad; Joseph, Alphonsa; Raole, Prakash Manohar; Barhai, Prema Kanta; Mukherjee, Subroto

2008-04-01

Direct current (DC) glow discharge plasma nitriding was carried out on three selected surface-roughened AISI 304 stainless steel samples at 833 K under 4 mbar pressures for 24 h in the presence of N 2 :H 2 gas mixtures of 50 : 50 ratios. After plasma nitriding, the phase formation, case depth, surface roughness, and microhardness of a plasma-nitrided layer were evaluated by glancing angle x-ray diffractogram, optical microscope, stylus profilometer, and Vickers microhardness tester techniques. The case depth, surface hardness, and phase formation variations were observed with a variation in initial surface roughness. The diffraction patterns of the plasma-nitrided samples showed the modified intensities of the α and γ phases along with those of the CrN, Fe 4 N, and Fe 3 N phases. Hardness and case depth variations were observed with a variation in surface roughness. A maximum hardness of 1058 Hv and a case depth of 95 μm were achieved in least surface-roughened samples.

Let Your Ions Shine.

ERIC Educational Resources Information Center

Koubek, Edward

1985-01-01

Outlines a demonstration involving weak acids and bases in aqueous solutions. A standard conductivity demonstration with a solution of acetic acid yields a barely glowing light bulb; a similar result occurs with ammonia solution. However, the bulb glows brightly when the solutions are mixed. (DH)

Unmasking a Hidden Glow

NASA Image and Video Library

2012-10-24

The image on the left shows a portion of our sky, called the Boötes field, in infrared light, while the image on the right shows a mysterious, background infrared glow captured by NASA Spitzer Space Telescope in the same region of sky.

Submillimeter-Wave Observations of C_3N^- in AN Extended Negative Glow Discharge

NASA Astrophysics Data System (ADS)

Amano, T.

2009-06-01

Extended negative glow and hollow anode discharges are found to be good sources of negative ions, such as CN^-, C_2H^-, and C_4H^-, for observations of pure rotational lines in the submillimeter-wave region. Thaddeus et al. detected C_3N^- in a glow discharge in HC_3N diluted in Ar buffer gas, and its rotational lines up to 378 GHz (J=39-38) were measured. In the present investigation, this anion has been observed in an extended negative glow discharge in a gas mixture of C_2N_2 (˜ 2 mTorr) and C_2H_2 (˜ 3 mTorr) in Ar buffer gas of ˜ 15 mTorr at the cell wall temperature of 230 K. The optimum discharge current was 2-4 mA with 250 Gauss longitudinal magnetic field. The rotational lines of up to J=51-50 in the 495 GHz region have been measured, and the improved rotational and centrifugal distortion constants are obtained. In the discharge optimum for production of C_3N^-, neither CN nor C_3N was detected with a similar signal accumulation time used for observations of the anion. However, this reaction has been found to be an excellent source for HC_3N, and the dominant formation mechanism of C_3N^- is likely to be the dissociative electron attachment to HC_3N. The radiative association of C_3N with electrons seems to be unlikely at least for the extended negative glow discharge. Apparently HC_3N is synthesized by a fast neutral and neutral reaction (C_2{H}_2 + CN → HC_3{N} + {H} It is interesting to see that an isomer, HCCNC, is also detected in the discharge, although the number density of this species is found to be about two orders of magnitude smaller than that of HC_3N. Another isomer, HNCCC, has also been observed with much weaker signal intensity. This species might have been produced by the dissociative recombination reaction of HC_3NH^+ with electrons, although the detection of this cation has not been successful in this type of discharge. T. Amano, J. Chem. Phys., 129, 244305 (2008). P. Thaddeus et al.,Astrophys. J., 677,1132-1139 (2008) K. Graupner et al., New J. Phys., 8,117 (2006) I. R. Sims et al.,Chem. Phys. Lett., 211, 461-468(1992) D. E. Woon and E. Herbst,Astrophys. J., 477, 204-208(1997)

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.

The effects of moon illumination, moon angle, cloud cover, and sky glow on night vision goggle flight performance

NASA Astrophysics Data System (ADS)

Loro, Stephen Lee

This study was designed to examine moon illumination, moon angle, cloud cover, sky glow, and Night Vision Goggle (NVG) flight performance to determine possible effects. The research was a causal-comparative design. The sample consisted of 194 Fort Rucker Initial Entry Rotary Wing NVG flight students being observed by 69 NVG Instructor Pilots. The students participated in NVG flight training from September 1992 through January 1993. Data were collected using a questionnaire. Observations were analyzed using a Kruskal-Wallis one-way analysis of variance and a Wilcox matched pairs signed-ranks test for difference. Correlations were analyzed using Pearson's r. The analyses results indicated that performance at high moon illumination levels is superior to zero moon illumination, and in most task maneuvers, superior to >0%--50% moon illumination. No differences were found in performance at moon illumination levels above 50%. Moon angle had no effect on night vision goggle flight performance. Cloud cover and sky glow have selective effects on different maneuvers. For most task maneuvers, cloud cover does not affect performance. Overcast cloud cover had a significant effect on seven of the 14 task maneuvers. Sky glow did not affect eight out of 14 task maneuvers at any level of sky glow.

Hypochondriacal attitudes comprise heterogeneous non-illness-related cognitions.

PubMed

Schwenzer, Michael; Mathiak, Klaus

2012-10-17

Hypochondriacal attitudes were associated with cognitions not related to illness: Social fears, low self-esteem, and reduced warm glow effect, i.e. less positive appraisal of familiar stimuli. Only a single study had investigated the correlation of hypochondriacal attitudes with the warm glow effect so far and the present study aimed to corroborate this association. Particularly, the present investigation tested for the first time whether social fears, low self-esteem, and reduced warm glow effect represent distinct or related biases in hypochondriacal attitudes. Fifty-five volunteers filled in the Hypochondriacal Beliefs and Disease Phobia scales of the Illness Attitude Scales, two scales enquiring social fears of criticism and intimacy, and the Rosenberg Self-Esteem Scale. The interaction of valence and spontaneous familiarity ratings of Chinese characters indicated the warm glow effect. A stepwise regression model revealed specific covariance of social fears and warm glow with hypochondriacal attitudes independent from the respective other variable. The correlation between low self-esteem and hypochondriacal attitudes missed significance. Hypochondriacal attitudes are embedded in a heterogeneous cluster of non-illness-related cognitions. Each social fears and a reduced cognitive capacity to associate two features--positive appraisal and familiarity--could diminish the susceptibility to safety signals such as medical reassurance. To compensate for reduced susceptibility to safety signals, multifocal treatment and repeated consultations appear advisable.

Corona-glow transition in the atmospheric pressure RF-excited plasma needle

NASA Astrophysics Data System (ADS)

Sakiyama, Y.; Graves, D. B.

2006-08-01

We present clear evidence of two different discharge modes of the atmospheric pressure RF-excited plasma needle and the transition mechanism by the finite element method. The gas used is helium with 0.1% nitrogen addition. The needle has a point-to-plane geometry with a radius of 30 µm at the tip, 150 µm at the base and an inter-electrode gap of 1 mm. We employ the one-moment fluid model with the local field approximation. Our simulation results indicate that the plasma needle operates as a corona discharge at low power and that the discharge mode transitions to a glow discharge at a critical power. The discharge power increases but the discharge voltage drops abruptly by a factor of about 2 in the corona-glow transition. The plasma density and ionization is confined near the needle tip in corona-mode while it spreads back along the needle surface in glow-mode. The corona-glow transition is also characterized by a dramatic decrease in sheath thickness and an order of magnitude increase in plasma density and volume-averaged ionization. The transition is observed whether or not secondary electron emission is included in the model, and therefore we suggest that this is not an α -γ transition.

Microgravity

NASA Image and Video Library

1997-01-01

The Forced Flow Flame-Spreading Test was designed to study flame spreading over solid fuels when air is flowing at a low speed in the same direction as the flame spread. Previous research has shown that in low-speed concurrent airflows, some materials are more flammable in microgravity than earth. This image shows a 10-cm flame in microgravity that burns almost entirely blue on both sides of a thin sheet of paper. The glowing thermocouple in the lower half of the flame provides temperature measurements.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zadora, A. S., E-mail: as.zadora@physics.msu.ru

The objective of the present study is to consider in more detail the exotic color-charge-glow effect discovered recently and to analyze its possible physical manifestations associated with the treatment of ensembles of color-charged particles at a classical level. The ways in which this effect may appear in arbitrary systems consisting of pointlike massive particles and admitting the partition into elementary configurations like color charges and color dipoles are studied. The possible influence of this effect on particle dynamics (in particular, on gluon distributions) is also examined. Particle collisions at a given impact parameters are considered for a natural regularization ofmore » emerging expressions. It is shown that, in the case of reasonable impact-parameter values, collisions may proceed in the electrodynamic mode, in which case the charge-glow contribution to field strengths is suppressed in relation to what we have in the electrodynamic picture. From an analysis of the color-echo situation, it follows that the above conclusion remains valid for more complicated particle configurations as well, since hard gluon fields may arise only owing to a direct collision rather than owing to any echo-like effects.« less

Study of constraints in using household NaCl salt for retrospective dosimetry

NASA Astrophysics Data System (ADS)

Elashmawy, M.

2018-05-01

Thermoluminescence (TL) characteristics of 5 different household NaCl salts and one analytical salt were determined to investigate the possible factors that affect the reliability of using household salt for retrospective dosimetry. Salts' TL sensitivities were found to be particle-size dependent and approached saturation at the largest size, whereas for salts that have the same particle size, the TL sensitivity depended on their origin. TL dependence on the particle size interprets significant variations in TL response reported in the literature for the same salt patch. The first TL readout indicated that all salts have similar glow curves with one distinctive peak. Typical second TL readout at two different doses showed a dramatic decrease in TL sensitivity associated with a significant change in the glow curve structure possessing two prominent peaks. Glow curve deconvolution (GCD) of the first TL readout for all salts yielded 6 individual glow peaks of first-order kinetics, whereas in GCD of second TL readouts, 5 individual glow peaks of second-order kinetics were obtained. Similarities in the glow curve structures of the first and second TL readouts suggest that additives such as KIO3 and MgCO3 have no effect on the TL process. Fading effect was evaluated for the salt of highest TL sensitivity, and it was found that the integral TL intensity decreased gradually and lost 40% of its initial value over 2 weeks, after which it remained constant. Results conclude that a household salt cannot be used for retrospective dosimetry without considering certain constraints such as the salt's origin and particle size. Furthermore, preparedness for radiological accidents and accurate dose reconstructions require that most of the commonly distributed household salt brands should be calibrated in advance and stored in a repository to be recalled in case of accidents.

Study of the Generation of Intense Pulsed Electron Beams Using Glow Discharges

DTIC Science & Technology

1988-02-01

de Investigaciones Opticas, Rep. Argentina. (2) On leave from PROFET (UNCPBA) Programa de Fisica Experimental Tandil, Rep. Argentina. (3) Edwards... de Investigaciones Opticas, (CIC-BA) Rep. Argentina. Section III-D. Measurements of the plasma density andB. T. Szapiro is on leave from Programa de ...discussed. The radial profiles Szapiro was supported by a fellowship from the Universidad Nacional de show the presence of a high-current-density

Glow phenomenon surrounding the vertical stabilizer and OMS pods

NASA Image and Video Library

1994-03-05

STS062-42-026 (4-18 March 1994) --- 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.

ScienceCast 102: Glow-in-the-Dark Plants on the ISS

NASA Image and Video Library

2013-05-03

Can plants adapt to the novelty of climate change? Researchers seeking to answer this question have sent genetically engineered plants to the ISS for exposure to extreme conditions. To report their condition, the plants have learned to glow in the dark.

The initial rise method extended to multiple trapping levels in thermoluminescent materials.

PubMed

Furetta, C; Guzmán, S; Ruiz, B; Cruz-Zaragoza, E

2011-02-01

The well known Initial Rise Method (IR) is commonly used to determine the activation energy when only one glow peak is presented and analysed in the phosphor materials. However, when the glow peak is more complex, a wide peak and some holders appear in the structure. The application of the Initial Rise Method is not valid because multiple trapping levels are considered and then the thermoluminescent analysis becomes difficult to perform. This paper shows the case of a complex glow curve structure as an example and shows that the calculation is also possible using the IR method. The aim of the paper is to extend the well known Initial Rise Method (IR) to the case of multiple trapping levels. The IR method is applied to minerals extracted from Nopal cactus and Oregano spices because the thermoluminescent glow curve's shape suggests a trap distribution instead of a single trapping level. Copyright © 2010 Elsevier Ltd. All rights reserved.

Using glow stick chemistry for biological imaging.

PubMed

Tseng, Jen-Chieh; Bailey, Dyane; Tupper, Tanya; Kung, Andrew L

2014-08-01

This study describes an imaging strategy based on glow stick chemistry to non-invasively image oxidative stress and reactive oxygen species (ROS) production in living animals. Upon stimulation, phagocytes produce toxic levels of ROS to kill engulfed microorganisms. The mitochondrial respiratory chain continually generates low levels of superoxide (O2·(-)) that serve as a source for generation of downstream ROS, which function as regulatory signaling intermediaries. A ROS-reacting substrate, 2-methyl-6-[4-methoxyphenyl]-3,7-dihydroimidazo[1,2-a]pyrazin-3-one hydrochloride, was used as the chemical energy donor for generating energy transfer luminescence in phagosomes and mitochondria. Using targeted photoluminescent dyes with specific subcellular localization that serve as chemical energy recipients, our imaging data demonstrate proof-of-concept for using glow stick chemistry to visualize ROS production associated with phagocytosis and mitochondrial respiration in living mice. Glow stick imaging is a complementary hybrid of chemiluminescence and photoluminescence imaging, capable of generating red or far-red emission for deep tissue imaging.

Failure to perceive increased risk of fracture in women 55 years and older: the Global Longitudinal Study of Osteoporosis in Women (GLOW)

PubMed Central

Gehlbach, S.; Adachi, J. D.; Boonen, S.; Chapurlat, R. D.; Compston, J. E.; Cooper, C.; Delmas, P.; Díez-Pérez, A.; Hooven, F. H.; LaCroix, A. Z.; Netelenbos, J. C.; Pfeilschifter, J.; Rossini, M.; Roux, C.; Saag, K. G.; Sambrook, P.; Silverman, S.; Watts, N. B.; Wyman, A.; Greenspan, S. L.

2010-01-01

Summary We compared self-perception of fracture risk with actual risk among 60,393 postmenopausal women aged ≥55 years, using data from the Global Longitudinal Study of Osteoporosis in Women (GLOW). Most postmenopausal women with risk factors failed to appreciate their actual risk for fracture. Improved education about osteoporosis risk factors is needed. Introduction This study seeks to compare self-perception of fracture risk with actual risk among postmenopausal women using data from GLOW. Methods GLOW is an international, observational, cohort study involving 723 physician practices in 17 sites in ten countries in Europe, North America, and Australia. Participants included 60,393 women ≥55 years attended by their physician during the previous 24 months. The sample was enriched so that two thirds were ≥65 years. Baseline surveys were mailed October 2006 to February 2008. Main outcome measures were self-perception of fracture risk in women with elevated risk vs women of the same age and frequency of risk factors for fragility fracture. Results In the overall study population, 19% (10,951/58,434) of women rated their risk of fracture as a little/much higher than that of women of the same age; 46% (27,138/58,434) said it was similar; 35% (20,345/58,434) believed it to be a little/much lower. Among women whose actual risk was increased based on the presence of any one of seven risk factors for fracture, the proportion who recognized their increased risk ranged from 19% for smokers to 39% for current users of glucocorticoid medication. Only 33% (4,185/12,612) of those with ≥2 risk factors perceived themselves as being at higher risk. Among women reporting a diagnosis of osteopenia or osteoporosis, only 25% and 43%, respectively, thought their risk was increased. Conclusion In this international, observational study, most postmenopausal women with risk factors failed to appreciate their actual risk for fracture. PMID:20358360

Data requirements for verification of ram glow chemistry

NASA Technical Reports Server (NTRS)

Swenson, G. R.; Mende, S. B.

1985-01-01

A set of questions is posed regarding the surface chemistry producing the ram glow on the space shuttle. The questions surround verification of the chemical cycle involved in the physical processes leading to the glow. The questions, and a matrix of measurements required for most answers, are presented. The measurements include knowledge of the flux composition to and from a ram surface as well as spectroscopic signatures from the U to visible to IR. A pallet set of experiments proposed to accomplish the measurements is discussed. An interim experiment involving an available infrared instrument to be operated from the shuttle Orbiter cabin is also be discussed.

Spectral characteristics of Shuttle glow

NASA Technical Reports Server (NTRS)

Viereck, R. A.; Mende, S. B.; Murad, E.; Swenson, G. R.; Pike, C. P.; Culbertson, F. L.; Springer, R. C.

1992-01-01

The glowing cloud near the ram surfaces of the Space Shuttle was observed with a hand-held, intensified spectrograph operated by the astronauts from the aft-flight-deck of the Space Shuttle. The spectral measurements were made between 400 and 800 nm with a resolution of 3 nm. Analysis of the spectral response of the instrument and the transmission of the Shuttle window was performed on orbit using earth-airglow OH Meinel bands. This analysis resulted in a correction of the Shuttle glow intensity in the spectral region between 700 and 800 nm. The data presented in this report is in better agreement with laboratory measurements of the NO2 continuum.

Preliminary Chaotic Model of Snapover on High Voltage Solar Cells

NASA Technical Reports Server (NTRS)

Mackey, Willie R.

1995-01-01

High voltage power systems in space will interact with the space plasma in a variety of ways. One of these, Snapover, is characterized by a sudden enlargement of the electron current collection area across normally insulating surfaces. A power drain on solar array power systems will results from this enhanced current collection. Optical observations of the snapover phenomena in the laboratory indicates a functional relation between bia potential and surface glow area. This paper shall explore the potential benefits of modeling the relation between current and bia potential as an aspect of bifurcation analysis in chaos theory. Successful characterizations of snapover as a chaotic phenomena may provide a means of snapover prevention and control through chaotic synchronization.

Launch Vehicle Performance for Bipropellant Propulsion Using Atomic Propellants With Oxygen

NASA Technical Reports Server (NTRS)

Palaszewski, Bryan

2000-01-01

Atomic propellants for bipropellant launch vehicles using atomic boron, carbon, and hydrogen were analyzed. The gross liftoff weights (GLOW) and dry masses of the vehicles were estimated, and the 'best' design points for atomic propellants were identified. Engine performance was estimated for a wide range of oxidizer to fuel (O/F) ratios, atom loadings in the solid hydrogen particles, and amounts of helium carrier fluid. Rocket vehicle GLOW was minimized by operating at an O/F ratio of 1.0 to 3.0 for the atomic boron and carbon cases. For the atomic hydrogen cases, a minimum GLOW occurred when using the fuel as a monopropellant (O/F = 0.0). The atomic vehicle dry masses are also presented, and these data exhibit minimum values at the same or similar O/F ratios as those for the vehicle GLOW. A technology assessment of atomic propellants has shown that atomic boron and carbon rocket analyses are considered to be much more near term options than the atomic hydrogen rockets. The technology for storing atomic boron and carbon has shown significant progress, while atomic hydrogen is not able to be stored at the high densities needed for effective propulsion. The GLOW and dry mass data can be used to estimate the cost of future vehicles and their atomic propellant production facilities. The lower the propellant's mass, the lower the overall investment for the specially manufactured atomic propellants.

Ion plating with an induction heating source

NASA Technical Reports Server (NTRS)

Spalvins, T.; Brainard, W. A.

1976-01-01

Induction heating is introduced as an evaporation heat source in ion plating. A bare induction coil without shielding can be directly used in the glow discharge region with no arcing. The only requirement is to utilize an rf inductive generator with low operating frequency of 75 kHz. Mechanical simplicity of the ion plating apparatus and ease of operation is a great asset for industrial applications; practically any metal such as nickel, iron, and the high temperature refractories can be evaporated and ion plated.

Rapid identification and desorption mechanisms of nitrogen-based explosives by ambient micro-fabricated glow discharge plasma desorption/ionization (MFGDP) mass spectrometry.

PubMed

Tian, CaiYan; Yin, JinWei; Zhao, ZhongJun; Zhang, Yinchenxi; Duan, YiXiang

2017-05-15

A novel technique of micro-fabricated glow discharge plasma desorption/ionization mass spectrometry was investigated for the first time in negative ion mode in this study. Negative ion micro-fabricated glow discharge plasma desorption/ionization mass spectrometry (NI-MFGDP-MS) was successfully applied to identify trace explosives in open air. Six explosives and explosives-related compounds were directly analyzed in seconds with this ion source. The ions of [M-H] - were predominant for 2-methyl-1,3,5-trinitrobenzene (trinitrotoluene, TNT) and 2,4,6-trinitrophenol (picric acid), and [M+NO 3 ] - were dominant ions for 1,3,5-trinitro-perhydro-1,3,5-triazine (cyclonite, RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (octogen, HMX), 1,2,3-trinitroxypropane (nitroglycerin, NG), and pentaerythritol tetranitrate (PETN). The limits of detection (LOD) were from 87.5pgmm -2 to 0.4 fg mm -2 and the relative standard deviation (RSD) ranged between 5.8% and 16.8% for the explosives involved in this study. The reliability of NI-MFGDP-MS was characterized by the analysis of a picric acid-RDX-PETN mixture and a mixture of RDX-pond water. NI-MFGDP-MS and ESI-MS were compared with these explosives and along with collision induced dissociation (CID) experiments. The results showed that electron capture, proton abstraction reaction, nucleophilic attack, ion-molecule attachment, decomposition and anion attachment took place during the NI-MFGDP-MS measurement. These findings provide a guideline and a supplement to the chemical libraries for rapid and accurate detection of explosives. The method shows great potential for fast, in situ, on-line and high throughput detection of explosives in the field of antiterrorism. Copyright © 2017 Elsevier B.V. All rights reserved.

Dynamics of plasma−dust structures formed in a trap created in the narrowing of a current channel in a magnetic field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dzlieva, E. S., E-mail: plasmadust@yandex.ru; Karasev, V. Yu., E-mail: v.karasev@spbu.ru; Pavlov, S. I.

The geometry and dynamics of plasma−dust structures in a longitudinal magnetic field is studied experimentally. The structures are formed in a glow-discharge trap created in the double electric layer produced as a result of discharge narrowing by means of a dielectric insert introduced in the discharge tube. Studies of structures formed in the new type of glow-discharge trap are of interest from the standpoint of future experiments with complex plasmas in superstrong magnetic fields in which the dust component is magnetized. Different types of dielectric inserts were used: conical and plane ones with symmetric and asymmetric apertures. Conditions for themore » existence of stable dust structures are determined for dust grains of different density and different dispersity. According to the experimental results, the angular velocity of dust rotation is ≥10 s{sup –1}, which is the fastest type of dust motion for all types of discharges in a magnetic field. The rotation is interpreted by analyzing the dynamics of individual dust grains.« less

Submerged Glow-Discharge Plasma: An Economical Approach to Convert Construction Scrap Metal into Nanomaterials

NASA Astrophysics Data System (ADS)

Yek, Peter Nai Yuh; Rafiq Mirza Julaihi, Muhammad; Shahril Osman, Mohammad; Tiong, Tung Chuan; Lee, Wak Ha; Leing Lee, Chern

2018-03-01

Submerged glow-discharge plasma (SGDP) is relatively new among the various methods available for nanomaterials synthesis (NMs) techniques. This method allows great control over the production cost of nanomaterials synthesis. A lab-scale batch type SDGP technology has been constructed to produce nanomaterials and investigate the inter-relationship between plasma excitation voltages, electrodes submerged areas and electrolyte concentration. Metal oxide nanospheres has been synthesised from different electrolyte concentrations (1M-0.001M) and characterized by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). As the major results showed that the nanospheres are uniformly spherical with diameter size distribution are between 100 nm - 2μm. EDS analysis shown the nano-Iron Oxide have been formed. Scrap metal initially showed around 6.45% and 93.55% of Carbon and Iron composition respectively. After SGDP process to the scrap metal, Carbon content has increased to 34-35% and Iron content has reduced to around 15-40%. EDS results also shown the higher percentage of Iron amount has remained with lower electrolyte concentration and Current is proportionally related to submersion area of cathode.

Kinetic study of low-temperature CO2 plasmas under non-equilibrium conditions. I. Relaxation of vibrational energy

NASA Astrophysics Data System (ADS)

Silva, T.; Grofulović, M.; Klarenaar, B. L. M.; Morillo-Candas, A. S.; Guaitella, O.; Engeln, R.; Pintassilgo, C. D.; Guerra, V.

2018-01-01

A kinetic model describing the time evolution of ˜70 individual CO2(X1Σ+) vibrational levels during the afterglow of a pulsed DC glow discharge is developed in order to contribute to the understanding of vibrational energy transfer in CO2 plasmas. The results of the simulations are compared against in situ Fourier transform infrared spectroscopy data obtained in a pulsed DC glow discharge and its afterglow at pressures of a few Torr and discharge currents of around 50 mA. The very good agreement between the model predictions and the experimental results validates the kinetic scheme considered here and the corresponding vibration-vibration and vibration-translation rate coefficients. In this sense, it establishes a reaction mechanism for the vibrational kinetics of these CO2 energy levels and offers a firm basis to understand the vibrational relaxation in CO2 plasmas. It is shown that first-order perturbation theories, namely, the Schwartz-Slawsky-Herzfeld and Sharma-Brau methods, provide a good description of CO2 vibrations under low excitation regimes.

Improved understanding of the hot cathode current modes and mode transitions

NASA Astrophysics Data System (ADS)

Campanell, M. D.; Umansky, M. V.

2017-12-01

Hot cathodes are crucial components in a variety of plasma sources and applications, but they induce mode transitions and oscillations that are not fully understood. It is often assumed that negatively biased hot cathodes have a space-charge limited (SCL) sheath whenever the current is limited. Here, we show on theoretical grounds that a SCL sheath cannot persist. First, charge-exchange ions born within the virtual cathode (VC) region get trapped and build up. After the ion density reaches the electron density at a point in the VC, a new neutral region is formed and begins growing in space. In planar geometry, this ‘new plasma’ containing cold trapped ions and cold thermoelectrons grows towards the anode and fills the gap, leaving behind an inverse cathode sheath. This explains how transitions from temperature-limited mode to anode glow mode occur in thermionic discharge experiments with magnetic fields. If the hot cathode is a small filament in an unmagnetized plasma, the trapped ion region is predicted to grow radially in both directions, get expelled if it reaches the cathode, and reform periodically. Filament-induced current oscillations consistent with this prediction have been reported in experiments. Here, we set up planar geometry simulations of thermionic discharges and demonstrate several mode transition phenomena for the first time. Our continuum kinetic code lacks the noise of particle simulations, enabling a closer study of the temporal dynamics.

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.

Control of plasma-liquid interaction of atmospheric DC glow discharge using liquid electrode

NASA Astrophysics Data System (ADS)

Shirai, Naoki; Aoki, Ryuta; Nito, Aihito; Aoki, Takuya; Uchida, Satoshi; Tochikubo, Fumiyoshi

2014-10-01

Atmospheric plasma in contact with liquid have a variety of interesting phenomena and applications. Previously, we investigated the fundamental characteristics of an atmospheric dc glow discharge using a liquid electrode with a miniature helium flow. We tried to control the plasma-liquid interaction by changing the plasma parameter such as gas species, liquid, and applied voltage. Sheath flow system enables another gas (N2, O2, Ar) flow to around the helium core flow. It can control the gas species around the discharge. When liquid (NaCl aq.) cathode DC discharge is generated, Na emission (588 nm) can be observed from liquid surface with increasing discharge current. Na emission strongly depends on the discharge current and liquid temperature. However, when Ar sheath flow is used, the intensity of Na becomes weak. When liquid anode DC discharge is generated, self-organized luminous pattern formation can be observed at the liquid surface. The pattern depends on existence of oxygen gas in gap. By changing the oxygen gas ratio in the gap, variety of pattern formation can be observed. The discharge in contact with liquid also can be used for synthesis of metal nanoparticles at plasma-liquid interface. Size and shape of nanoparticles depend on discharge gases. This work was supported financially in part by a Grant-in-Aid for Scientific Research on Innovative Areas (No 21110007) from MEXT, Japan.

Quantification of the effect of surface heating on shock wave modification by a plasma actuator in a low-density supersonic flow over a flat plate

NASA Astrophysics Data System (ADS)

Joussot, Romain; Lago, Viviana; Parisse, Jean-Denis

2015-05-01

This paper describes experimental and numerical investigations focused on the shock wave modification induced by a dc glow discharge. The model is a flat plate in a Mach 2 air flow, equipped with a plasma actuator composed of two electrodes. A weakly ionized plasma was created above the plate by generating a glow discharge with a negative dc potential applied to the upstream electrode. The natural flow exhibited a shock wave with a hyperbolic shape. Pitot measurements and ICCD images of the modified flow revealed that when the discharge was ignited, the shock wave angle increased with the discharge current. The spatial distribution of the surface temperature was measured with an IR camera. The surface temperature increased with the current and decreased along the model. The temperature distribution was reproduced experimentally by placing a heating element instead of the active electrode, and numerically by modifying the boundary condition at the model surface. For the same surface temperature, experimental investigations showed that the shock wave angle was lower with the heating element than for the case with the discharge switched on. The results show that surface heating is responsible for roughly 50 % of the shock wave angle increase, meaning that purely plasma effects must also be considered to fully explain the flow modifications observed.

Diagnostics of reactive oxygen species produced by microplasmas

NASA Astrophysics Data System (ADS)

Sousa, J. S.; Puech, V.

2013-11-01

Atmospheric pressure generation of reactive oxygen species (ROS) by microplasmas was experimentally studied. The remarkable stability of the microcathode sustained discharge (MCSD) allowed the operation of dc glow discharges, free from the glow-to-arc transition, in He/O2/NO mixtures at atmospheric pressure. Absolute densities of the main ROS were measured by different optical diagnostics: singlet delta oxygen (O2(a 1Δg)) by infrared emission and vacuum ultraviolet absorption in the effluent, ozone (O3) by ultraviolet absorption in the effluent, and atomic oxygen inside the discharge by two-photon absorption laser induced fluorescence. The effect of different parameters, such as gas flow and mixture, and discharge current, on the production of these ROS was studied. High ROS densities up to 1016 cm-3 were achieved. It is shown that the density ratio of O2(a 1Δg) to O3 can be finely tuned in the range [10-3-10+4], through the values of discharge current and NO concentration, and that high O2(a 1Δg) and O3 densities can be transported over distances longer than 50 cm. The MCSD is, thus, a very suitable tool for the continuous production at atmospheric pressure of large fluxes of O2(a 1Δg) and O3, useful to a wide range of applications, notably in plasma medicine.

Boundary Layer Flow Control with a One Atmosphere Uniform Glow Discharge Surface Plasma

NASA Technical Reports Server (NTRS)

Roth, J. Reece; Sherman, Daniel M.; Wilkinson, Stephen P.

1998-01-01

Low speed wind tunnel data have been acquired for planar panels covered by a uniform, glow-discharge surface plasma in atmospheric pressure air known as the One Atmosphere Uniform Glow Discharge Plasma (OAUGDP). Streamwise and spanwise arrays of flush, plasma-generating surface electrodes have been studied in laminar, transitional, and fully turbulent boundary layer flow. Plasma between symmetric streamwise electrode strips caused large increases in panel drag, whereas asymmetric spanwise electrode configurations produced a significant thrust. Smoke wire flow visualization and mean velocity diagnostics show the primary cause of the phenomena to be a combination of mass transport and vortical structures induced by strong paraelectric ElectroHydroDynamic (EHD) body forces on the flow.

Improved understanding of the hot cathode current modes and mode transitions [Mechanism of the hot cathode current mode transitions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Campanell, Michael D.; Umansky, M. V.

Hot cathodes are crucial components in a variety of plasma sources and applications, but they induce mode transitions and oscillations that are not fully understood. It is often assumed that negatively biased hot cathodes have a space-charge limited (SCL) sheath whenever the current is limited. Here, we show on theoretical grounds that a SCL sheath cannot persist. First, charge-exchange ions born within the virtual cathode (VC) region get trapped and build up. After the ion density reaches the electron density at a point in the VC, a new neutral region is formed and begins growing in space. In planar geometry,more » this 'new plasma' containing cold trapped ions and cold thermoelectrons grows towards the anode and fills the gap, leaving behind an inverse cathode sheath. This explains how transitions from temperature-limited mode to anode glow mode occur in thermionic discharge experiments with magnetic fields. If the hot cathode is a small filament in an unmagnetized plasma, the trapped ion region is predicted to grow radially in both directions, get expelled if it reaches the cathode, and reform periodically. Filament-induced current oscillations consistent with this prediction have been reported in experiments. Here, we set up planar geometry simulations of thermionic discharges and demonstrate several mode transition phenomena for the first time. Lastly, our continuum kinetic code lacks the noise of particle simulations, enabling a closer study of the temporal dynamics.« less

Improved understanding of the hot cathode current modes and mode transitions [Mechanism of the hot cathode current mode transitions

DOE PAGES

Campanell, Michael D.; Umansky, M. V.

2017-11-22

Hot cathodes are crucial components in a variety of plasma sources and applications, but they induce mode transitions and oscillations that are not fully understood. It is often assumed that negatively biased hot cathodes have a space-charge limited (SCL) sheath whenever the current is limited. Here, we show on theoretical grounds that a SCL sheath cannot persist. First, charge-exchange ions born within the virtual cathode (VC) region get trapped and build up. After the ion density reaches the electron density at a point in the VC, a new neutral region is formed and begins growing in space. In planar geometry,more » this 'new plasma' containing cold trapped ions and cold thermoelectrons grows towards the anode and fills the gap, leaving behind an inverse cathode sheath. This explains how transitions from temperature-limited mode to anode glow mode occur in thermionic discharge experiments with magnetic fields. If the hot cathode is a small filament in an unmagnetized plasma, the trapped ion region is predicted to grow radially in both directions, get expelled if it reaches the cathode, and reform periodically. Filament-induced current oscillations consistent with this prediction have been reported in experiments. Here, we set up planar geometry simulations of thermionic discharges and demonstrate several mode transition phenomena for the first time. Lastly, our continuum kinetic code lacks the noise of particle simulations, enabling a closer study of the temporal dynamics.« less

Microwave Synthesis of a Long-Lasting Phosphor

ERIC Educational Resources Information Center

Filhol, Jean-Sebastien; Zitoun, David; Bernaud, Laurent; Manteghetti, Alain

2009-01-01

Efficient glow-in-the-dark materials are usually difficult to synthesize and need complex experiments with long reaction times that are not appropriate for conventional lab teaching. Therefore, we describe a new experimental procedure that allows the production of one of the most efficient "glow-in-the-dark" materials (SrAl[subscript 2]O[subscript…

Sky Glow from Cities: The Army Illumination Model v2

DTIC Science & Technology

2011-09-01

magnetic field and is negligible. Zodiacal light is sunlight scattered by interplanetary dust and contributes up to half the brightness of the ...Sky Glow from Cities: The Army Illumination Model v2 by Richard C. Shirkey ARL-TR-5719 September 2011...Approved for public release; distribution is unlimited. NOTICES Disclaimers The

Second Workshop on Spacecraft Glow

NASA Technical Reports Server (NTRS)

Waite, J. H., Jr. (Editor); Moorehead, T. W. (Editor)

1985-01-01

Various aspects of space glow were considered. Results of a workshop held on May 6 to 7, 1985, at the Space Science Laboratory of NASA/Marshall Space Flight Center, Huntsville, Alabama are presented. The topics of discussion are divided as follows: (1) in situ observations; (2) theoretical calculations; (3) laboratory measurements; and (4) future experiments.

Charged Particle Distribution near the Shock Front in a Glow Discharge

NASA Astrophysics Data System (ADS)

Baryshnikov, A. S.; Basargin, I. V.; Bezverkhnii, N. O.; Bobashev, S. V.; Monakhov, N. A.; Popov, P. A.; Sakharov, V. A.; Chistyakova, M. V.

2018-02-01

The charged particle distribution near the front of a shock wave propagating in the glow discharge plasma has been investigated. It has been found that the ion concentration before the front varies nonmonotonically. Behind the shock front, the charged particle concentration varies smoothly in contrast to the neutral component density.

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…

Spectral identification/elimination of molecular species in spacecraft glow

NASA Technical Reports Server (NTRS)

Green, B. D.; Marinelli, W. J.; Rawlins, W. T.

1985-01-01

Computer models of molecular electronic and vibrational emission intensities were developed. Known radiative emission rates (Einstein coefficients) permit the determination of relative excited state densities from spectral intensities. These codes were applied to the published spectra of glow above shuttle surface and to the Spacelab 1 results of Torr and Torr. The theoretical high-resolution spectra were convolved with the appropriate instrumental slit functions to allow accurate comparison with data. The published spacelab spectrum is complex but N2+ Meinel emission can be clearly identified in the ram spectrum. M2 First Positive emission does not correlate well with observed features, nor does the CN Red System. Spectral overlay comparisons are presented. The spectrum of glow above shuttle surfaces, in contrast to the ISO data, is not highly structured. Diatomic molecular emission was matched to the observed spectral shape. Source excitation mechanisms such as (oxygen atom)-(surface species) reaction product chemiluminescence, surface recombination, or resonance fluorescent re-emission will be discussed for each tentative assignment. These assignments are the necessary first analytical step toward mechanism identification. Different glow mechanisms will occur above surfaces under different orbital conditions.

Synthesis, characteristics and thermoluminescent dosimetry features of γ-irradiated Ce doped CaF2 nanophosphor.

PubMed

Zahedifar, M; Sadeghi, E; Mozdianfard, M R; Habibi, E

2013-08-01

Nanoparticles of cerium doped calcium fluoride (CaF2:Ce) were synthesized for the first time using the hydrothermal method. The formation of nanostructures was confirmed by X-ray diffraction (XRD) patterns, indicating cubic lattice structure for the particles produced. Their shape and size were observed by scanning electron microscopy (SEM). Thermoluminescence characteristics were studied by having the samples irradiated by gamma rays of (60)Co source. The optimum thermal treatment of 400 °C for 30 min was found for the produced nanoparticles. The Tm-Tstop and computerized glow curve deconvolution (CGCD) methods, used to determine the number of component glow peaks and kinetic parameters, indicated seven overlapping glow peaks on the TL glow curve at approximately 394, 411, 425, 445, 556, 594 and 632 K. A linear dose response of up to 2000 Gy, was observed for the prepared nanoparticles. Maximum TL sensitivity was found at 0.4 mol% of Ce impurity. Other TL dosimetry features, including reusability and fading, were also presented and discussed. Copyright © 2013 Elsevier Ltd. All rights reserved.

[Design and experiment of a needle-to-cylinder electrode structure realizing the negative DC glow discharge in ambient air].

PubMed

Li, Hua; Wei, Chang-Yan; Liu, Chun-Xia; Shen, Xian-Hao; Chen, Zhen-Cheng

2014-07-01

A new needle-to-cylinder electrode structure was designed to realize the stable glow discharge in ambient air. The stainless steel needle tip with diameter 56.4 microm and the copper cylinder with diameter 4mm were chosen as the cathode and the anode respectively, which were kept parallel by accurate mechanical structure. In the condition that the distance between the needle and the cylinder is 2 mm, the ballasting resistor is 10 M(omega), the discharge resistor is 10 M(omega), the testing resistor is 1 k(omega), and the discharge voltage is -2 740 V, without air flow in ambient air and at room temperature, the stable glow discharge between the needle and the cylinder was realized. Three different discharge modes can be observed: corona discharge, glow discharge and spark, which were verified by the discharge waveform stored in the oscilloscope, and the discharge pictures were recorded by digital camera. The needle-to-cylinder electrode structure is easy to fabricate by the MEMS technology, which can be used as the ion source of the portable analyzing instruments.

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.

Thermoluminescence glow curve deconvolution and trapping parameters determination of dysprosium doped magnesium borate glass

NASA Astrophysics Data System (ADS)

Salama, E.; Soliman, H. A.

2018-07-01

In this paper, thermoluminescence glow curves of gamma irradiated magnesium borate glass doped with dysprosium were studied. The number of interfering peaks and in turn the number of electron trap levels are determined using the Repeated Initial Rise (RIR) method. At different heating rates (β), the glow curves were deconvoluted into two interfering peaks based on the results of RIR method. Kinetic parameters such as trap depth, kinetic order (b) and frequency factor (s) for each electron trap level is determined using the Peak Shape (PS) method. The obtained results indicated that, the magnesium borate glass doped with dysprosium has two electron trap levels with the average depth energies of 0.63 and 0.79 eV respectively. These two traps have second order kinetic and are formed at low temperature region. The obtained results due to the glow curve analysis could be used to explain some observed properties such as, high thermal fading and light sensitivity for such thermoluminescence material. In this work, systematic procedures to determine the kinetic parameters of any thermoluminescence material are successfully introduced.

Directly observable optical properties of sprites in Central Europe

NASA Astrophysics Data System (ADS)

Bór, József

2013-04-01

Luminous optical emissions accompanying streamer-based natural electric breakdown processes initiating in the mesosphere are called sprites. 489 sprite events have been observed with a TV frame rate video system in Central Europe from Sopron (47.68N, 16.58E, 230 m MSL), Hungary between 2007 and 2009. On the basis of these observations, characteristic morphological properties of sprites, i.e. basic forms (e.g. column, carrot, angel, etc.) as well as common morphological features (e.g. tendrils, glows, puffs, beads, etc.), have been identified. Probable time sequences of streamer propagation directions were associated with each of the basic sprite forms. It is speculated that different sequences of streamer propagation directions can result in very similar final sprite shapes. The number and type variety of sprite elements appearing in an event as well as the total optical duration of an event was analyzed statistically. Jellyfish and dancing sprite events were considered as special subsets of sprite clusters. It was found that more than 90% of the recorded sprite elements appeared in clusters rather than alone and more than half of the clusters contained more than one basic sprite forms. The analysis showed that jellyfish sprites and clusters of column sprites featuring glows and tendrils do not tend to have optical lifetimes longer than 80 ms. Such very long optical lifetimes have not been observed in sprite clusters containing more than 25 elements of any type, either. In contrast to clusters containing sprite entities of only one form, sprite events showing more sprite forms seem to have extended optical durations more likely. The need for further investigation and for finding theoretical concepts to link these observations to electric conditions ambient for sprite formation is emphasized.

SkyGlowNet as a Vehicle for STEM Education

NASA Astrophysics Data System (ADS)

Flurchick, K. M.; Craine, E. R.; Culver, R. B.; Deal, S.; Foster, C.

2013-06-01

SkyGlowNet is an emerging network of internet-enabled sky brightness meters (iSBM) that continuously record and log sky brightness at the zenith of each network node site. Also logged are time and weather information. These data are polled at a user-defined frequency, typically about every 45 seconds. The data are uploaded to the SkyGlowNet website, initially to a proprietary area where the data for each institution are embargoed for one or two semesters as students conduct research projects with their data. When released from embargo, the data are moved to another area where they can be accessed by all SkyGlowNet participants. Some of the data are periodically released to a public area on the website. In this presentation we describe the data formats and provide examples of both data content and the structure of the website. Early data from two nodes in the SkyGlowNet have been characterized, both quantitatively and qualitatively, by undergraduate students at NCAT. A summary of their work is presented here. These analyses are of utility in helping those new to looking at these data to understand how to interpret them. In particular, we demonstrate differences between effects on light at night and sky brightness due to astronomical cycles, atmospheric phenomena, and artificial lighting. Quantitative characterization of the data includes statistical analyses of parsed segments of the temporal data stream. An attempt is made to relate statistical metrics to specific types of phenomena.

The multisensor payload 'Structura' for the observation of atmospheric night glows from the ISS board

NASA Astrophysics Data System (ADS)

Krot, Yury; Beliaev, Boris; Katkovsky, Leonid

2016-10-01

Aerospace Research Department of the Institute of Applied Physical Problems at Belarusian State University has developed a prototype of the optical payload intended for a space experiment on the ISS board. The prototype includes four optical modules for the night glows observation, in particular spatial-brightness and spectral characteristics in the altitude range of 80-320 km. Objects of the interest are emitting top layers of the atmosphere including exited OH radicals, atomic and molecular oxygen and sodium layers. The goal of the space experiment is a research of night glows over different regions of the Earth and a connection with natural disasters like earthquakes, cyclones, etc. Two optical modules for spatial distribution of atomic oxygen layers along the altitude consist of input lenses, spectral interferential filters and line CCD detectors. The optical module for registration of exited OH radical emissions is formed from CCD array spectrometer. The payload includes also a panchromatic (400-900 nm) high sensitive imaging camera for observing of the glows general picture. The optical modules of the prototype have been tested and general optical characteristics were determined in laboratory conditions. A solution of an astigmatism reducing of a concave diffraction grating and a method of the second diffraction order correction were applied and improved spectrometer's optical characteristics. Laboratory equipment and software were developed to imitate a dynamic scene of the night glows in laboratory conditions including an imitation of linear spectra and the spatial distribution of emissions.

Astronomers Image Lowest-mass Exoplanet Around a Sun-like Star

NASA Image and Video Library

2017-12-08

Caption: Glowing a dark magenta, the newly discovered exoplanet GJ 504b weighs in with about four times Jupiter's mass, making it the lowest-mass planet ever directly imaged around a star like the sun. Credit: NASA/Goddard/S. Wiessinger Using infrared data from the Subaru Telescope in Hawaii, an international team of astronomers has imaged a giant planet around the bright star GJ 504. Several times the mass of Jupiter and similar in size, the new world, dubbed GJ 504b, is the lowest-mass planet ever detected around a star like the sun using direct imaging techniques. "If we could travel to this giant planet, we would see a world still glowing from the heat of its formation with a color reminiscent of a dark cherry blossom, a dull magenta," said Michael McElwain, a member of the discovery team at NASA's Goddard Space Flight Center in Greenbelt, Md. "Our near-infrared camera reveals that its color is much more blue than other imaged planets, which may indicate that its atmosphere has fewer clouds." Read more: 1.usa.gov/15Ba6fI NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Modeling of glow discharge in a gas flow

NASA Astrophysics Data System (ADS)

Galeev, I. G.; Asadullin, T. Ya

2017-11-01

The discharge plasma of positive column in electronegative gas flow has been described by two-dimensional integro-differential system of equations written in the approximation of “narrow channel”. An efficient algorithm of solving this system of equations is suggested. In this work an implicit method is used of solution with selection gradient of the electric field along the channel. The simulation of discharge characteristics was conducted under various boundary conditions at the inlet of the discharge area and with various full discharge currents.

Gays and Lesbians Older and Wiser (GLOW): A Support Group for Older Gay People.

ERIC Educational Resources Information Center

Slusher, Morgan P.; And Others

1996-01-01

Describes Gays and Lesbians Older and Wiser (GLOW), a support group sponsored by a geriatric medical clinic in the midwestern United States. Scheduling, professional involvement, and special attention to social support seem critical for the group's success. Concludes that carefully designed support groups can meet some support needs for this older…

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 × 1017 ions/cm2. 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.

Neural responses to taxation and voluntary giving reveal motives for charitable donations.

PubMed

Harbaugh, William T; Mayr, Ulrich; Burghart, Daniel R

2007-06-15

Civil societies function because people pay taxes and make charitable contributions to provide public goods. One possible motive for charitable contributions, called "pure altruism," is satisfied by increases in the public good no matter the source or intent. Another possible motive, "warm glow," is only fulfilled by an individual's own voluntary donations. Consistent with pure altruism, we find that even mandatory, tax-like transfers to a charity elicit neural activity in areas linked to reward processing. Moreover, neural responses to the charity's financial gains predict voluntary giving. However, consistent with warm glow, neural activity further increases when people make transfers voluntarily. Both pure altruism and warm-glow motives appear to determine the hedonic consequences of financial transfers to the public good.

Gas chromatography coupled to tunable pulsed glow discharge time-of-flight mass spectrometry for environmental analysis.

PubMed

Solà-Vázquez, Auristela; Lara-Gonzalo, Azucena; Costa-Fernández, José M; Pereiro, Rosario; Sanz-Medel, Alfredo

2010-05-01

A tuneable microsecond pulsed direct current glow discharge (GD)-time-of-flight mass spectrometer MS(TOF) developed in our laboratory was coupled to a gas chromatograph (GC) to obtain sequential collection of the mass spectra, at different temporal regimes occurring in the GD pulses, during elution of the analytes. The capabilities of this set-up were explored using a mixture of volatile organic compounds of environmental concern: BrClCH, Cl(3)CH, Cl(4)C, BrCl(2)CH, Br(2)ClCH, Br(3)CH. The experimental parameters of the GC-pulsed GD-MS(TOF) prototype were optimized in order to separate appropriately and analyze the six selected organic compounds, and two GC carrier gases, helium and nitrogen, were evaluated. Mass spectra for all analytes were obtained in the prepeak, plateau and afterpeak temporal regimes of the pulsed GD. Results showed that helium offered the best elemental sensitivity, while nitrogen provided higher signal intensities for fragments and molecular peaks. The analytical performance characteristics were also worked out for each analyte. Absolute detection limits obtained were in the order of ng. In a second step, headspace solid phase microextraction (HS SPME), as sample preparation and preconcentration technique, was evaluated for the quantification of the compounds under study, in order to achieve the required analytical sensitivity for trihalomethanes European Union (EU) environmental legislation. The analytical figures of merit obtained using the proposed methodology showed rather good detection limits (between 2 and 13 microg L(-1) depending on the analyte). In fact, the developed methodology met the EU legislation requirements (the maximum level permitted in tap water for the "total trihalomethanes" is set at 100 microg L(-1)). Real analysis of drinking water and river water were successfully carried out. To our knowledge this is the first application of GC-pulsed GD-MS(TOF) for the analysis of real samples. Its ability to provide elemental, fragments and molecular information of the organic compounds is demonstrated.

A Cosmic Holiday Ornament, Hubble-Style

NASA Image and Video Library

2017-12-08

'Tis the season for holiday decorating and tree-trimming. Not to be left out, astronomers using NASA's Hubble Space Telescope have photographed a festive-looking nearby planetary nebula called NGC 5189. The intricate structure of this bright gaseous nebula resembles a glass-blown holiday ornament with a glowing ribbon entwined. Planetary nebulae represent the final brief stage in the life of a medium-sized star like our sun. While consuming the last of the fuel in its core, the dying star expels a large portion of its outer envelope. This material then becomes heated by the radiation from the stellar remnant and radiates, producing glowing clouds of gas that can show complex structures, as the ejection of mass from the star is uneven in both time and direction. To read more go to: www.nasa.gov/mission_pages/hubble/science/ngc5189.html Credit: NASA, ESA, and G. Bacon (STScI) NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Wire chamber radiation detector with discharge control

DOEpatents

Perez-Mendez, Victor; Mulera, Terrence A.

1984-01-01

A wire chamber radiation detector (11) has spaced apart parallel electrodes (16) and grids (17, 18, 19) defining an ignition region (21) in which charged particles (12) or other ionizing radiations initiate brief localized avalanche discharges (93) and defining an adjacent memory region (22) in which sustained glow discharges (94) are initiated by the primary discharges (93). Conductors (29, 32) of the grids (18, 19) at each side of the memory section (22) extend in orthogonal directions enabling readout of the X-Y coordinates of locations at which charged particles (12) were detected by sequentially transmitting pulses to the conductors (29) of one grid (18) while detecting transmissions of the pulses to the orthogonal conductors (36) of the other grid (19) through glow discharges (94). One of the grids (19) bounding the memory region (22) is defined by an array of conductive elements (32) each of which is connected to the associated readout conductor (36) through a separate resistance (37). The wire chamber (11) avoids ambiguities and imprecisions in the readout of coordinates when large numbers of simultaneous or near simultaneous charged particles (12) have been detected. Down time between detection periods and the generation of radio frequency noise are also reduced.

Experimental investigation of flow induced dust acoustic shock waves in a complex plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jaiswal, S., E-mail: surabhijaiswal73@gmail.com; Bandyopadhyay, P.; Sen, A.

2016-08-15

We report on experimental observations of flow induced large amplitude dust-acoustic shock waves in a complex plasma. The experiments have been carried out in a Π shaped direct current glow discharge experimental device using kaolin particles as the dust component in a background of Argon plasma. A strong supersonic flow of the dust fluid is induced by adjusting the pumping speed and neutral gas flow into the device. An isolated copper wire mounted on the cathode acts as a potential barrier to the flow of dust particles. A sudden change in the gas flow rate is used to trigger themore » onset of high velocity dust acoustic shocks whose dynamics are captured by fast video pictures of the evolving structures. The physical characteristics of these shocks are delineated through a parametric scan of their dynamical properties over a range of flow speeds and potential hill heights. The observed evolution of the shock waves and their propagation characteristics are found to compare well with model numerical results based on a modified Korteweg-de-Vries-Burgers type equation.« less

Influence of Cobalt on the Adhesion Strength of Polycrystalline Diamond Coatings on WC-Co Hard Alloys

NASA Astrophysics Data System (ADS)

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

2018-02-01

The influence of cobalt on the phase composition and adhesion strength of polycrystalline diamond coatings has been studied using scanning electron microscopy, Raman spectroscopy, and X-ray microanalysis. The coatings have been deposited on WC-Co hard alloy substrates in glow discharge plasma. It has been found that the catalytic amorphization of carbon only takes place during the direct synthesis of the diamond coating, when the cobalt vapor pressure over the substrate is high and the cobalt-related degradation of the synthesized diamond is absent.

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

NASA Astrophysics Data System (ADS)

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

1999-02-01

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

Thiol surface functionalization via continuous phase plasma polymerization of allyl mercaptan, with subsequent maleimide-linked conjugation of collagen.

PubMed

Stynes, Gil D; Gengenbach, Thomas R; Kiroff, George K; Morrison, Wayne A; Kirkland, Mark A

2017-07-01

Thiol groups can undergo a large variety of chemical reactions and are used in solution phase to conjugate many bioactive molecules. Previous research on solid substrates with continuous phase glow discharge polymerization of thiol-containing monomers may have been compromised by oxidation. Thiol surface functionalization via glow discharge polymerization has been reported as requiring pulsing. Herein, continuous phase glow discharge polymerization of allyl mercaptan (2-propene-1-thiol) was used to generate significant densities of thiol groups on a mixed macrodiol polyurethane and tantalum. Three general classes of chemistry are used to conjugate proteins to thiol groups, with maleimide linkers being used most commonly. Here the pH specificity of maleimide reactions was used effectively to conjugate surface-bound thiol groups to amine groups in collagen. XPS demonstrated surface-bound thiol groups without evidence of oxidation, along with the subsequent presence of maleimide and collagen. Glow discharge reactor parameters were optimized by testing the resistance of bound collagen to degradation by 8 M urea. The nature of the chemical bonding of collagen to surface thiol groups was effectively assessed by colorimetric assay (ELISA) of residual collagen after incubation in 8 M urea over 8 days and after incubation with keratinocytes over 15 days. The facile creation of useable solid-supported thiol groups via continuous phase glow discharge polymerization of allyl mercaptan opens a route for attaching a vast array of bioactive molecules. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1940-1948, 2017. © 2017 Wiley Periodicals, Inc.

Effect of 100 MeV swift Si8+ ions on structural and thermoluminescence properties of Y2O3:Dy3+nanophosphor

NASA Astrophysics Data System (ADS)

Shivaramu, N. J.; Lakshminarasappa, B. N.; Nagabhushana, K. R.; Singh, Fouran

2016-05-01

Nanoparticles of Y2O3:Dy3+ were prepared by the solution combustion method. The X-ray diffraction pattern of the 900°C annealed sample shows a cubic structure and the average crystallite size was found to be 31.49 nm. The field emission scanning electron microscopy image of the 900°C annealed sample shows well-separated spherical shape particles and the average particle size is found to be in a range 40 nm. Pellets of Y2O3:Dy3+ were irradiated with 100 MeV swift Si8+ ions for the fluence range of 3 × 1011_3 × 1013 ions cm-2. Pristine Y2O3:Dy3+ shows seven Raman modes with peaks at 129, 160, 330, 376, 434, 467 and 590 cm-1. The intensity of these modes decreases with an increase in ion fluence. A well-resolved thermoluminescence glow with peaks at ∼414 K (Tm1) and ∼614 K (Tm2) were observed in Si8+ ion-irradiated samples. It is found that glow peak intensity at 414 K increases with an increase in the dopant concentration up to 0.6 mol% and then decreases with an increase in dopant concentration. The high-temperature glow peak (614 K) intensity linearly increases with an increase in ion fluence. The broad TL glow curves were deconvoluted using the glow curve deconvoluted method and kinetic parameters were calculated using the general order kinetic equation.

Apparatus for determining glowing combustibility of thin fuels

Treesearch

D.C. Jones; A. Broido

1971-01-01

Leaflike samples, approximately 8 cm in diameter, are held at the end of a mechanical arm which reproducibly controls sample movement during the ignition and burn ing process. Glowing combustion is induced by bringing the sample into contact with a small loop in an electrically heated nichrome wire. The ultimate burned-out area is measured 1n an ultraviolet detection...

Method of fabricating n-type and p-type microcrystalline semiconductor alloy material including band gap widening elements

DOEpatents

Guha, Subhendu; Ovshinsky, Stanford R.

1990-02-02

A method of fabricating doped microcrystalline semiconductor alloy material which includes a band gap widening element through a glow discharge deposition process by subjecting a precursor mixture which includes a diluent gas to an a.c. glow discharge in the absence of a magnetic field of sufficient strength to induce electron cyclotron resonance.

Influence of Operating Parameters on Surface Properties of RF Glow Discharge Oxygen Plasma Treated TiO2/PET Film for Biomedical Application

EPA Science Inventory

Thin transparent titania (TiO2) films were coated on the surface of flexible poly (ethylene terephthalate) (PET) surface using standard sol gel techniques. The TiO2/PET thin film surfaces were further modified by exposing the films to a RF glow discharge oxygen plasma. The exposu...

Energetics of photosynthetic glow peaks

PubMed Central

DeVault, Don; Govindjee; Arnold, William

1983-01-01

By postulating temperature-dependent equilibria between two or more electron carriers acting as traps for electrons or holes, it is possible to modify the Randall-Wilkins theory of thermoluminescence so as to explain the abnormally large apparent activation energies and apparent frequency factors observed in photosynthetic glow curves when fitted by unmodified Randall-Wilkins theory. The equilibria serve to inhibit the formation of the light-emitting excited state by withholding the needed precursor state. When the inhibition is released at higher temperature by shift of equilibrium with temperature, the rise of the glow peak can be much faster than would result from Arrhenius behavior based on the true activation energy and so appears to correspond to a higher activation energy accompanied by a larger frequency factor. From another viewpoint, the enthalpy changes, ΔH, of the equilibria tend to add to the activation energy. Similarly the entropy changes, ΔS, of the equilibria tend to add to the entropy of activation, giving the large apparent frequency factors. The positive values of ΔS needed would correspond to entropy decreases in the forward early electron transport. A comparison of the glow peaks obtained by different workers is also presented. PMID:16593283

Development of new UV-I. I. Cerenkov Viewing Device

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuribara, Masayuki; Nemoto, Koshichi

1994-02-01

The Cerenkov glow images from boiling-water reactors (BWR) and pressurized-water reactors (PWR) irradiated fuel assemblies are generally used for inspections. However, sometimes it is difficult or impossible to identify the image by the conventional Cerenkov Viewing Device (CVD), because of the long cooling time and/or low burnup. Now a new UV-I.I. (Ultra-Violet light Image Intensifier) CVD has been developed, which can detect the very weak Cerenkov glow from spent fuel assemblies. As this new device uses the newly developed proximity focused type UV-I.I., Cerenkov photons are used efficiently, producing better quality Cerenkov glow images. Moreover, since the image is convertedmore » to a video signal, it is easy to improve the signal to noise ratio (S/N) by an image processor. The new CVD was tested at BWR and PWR power plants in Japan, with fuel burnups ranging from 6,200--33,000 MWD/MTU (megawatt days per metric ton of uranium) and cooling times ranging from 370 to 6,200 d. The tests showed that the new CVD is superior to the conventional STA/CRIEPI CVD, and could detect very feeble Cerenkov glow images using an image processor.« less

Luminescence studies of rare earth doped yttrium gadolinium mixed oxide phosphor

NASA Astrophysics Data System (ADS)

Som, S.; Choubey, A.; Sharma, S. K.

2012-09-01

This paper reports the photoluminescence and thermoluminescence properties of gamma ray induced rare earth doped yttrium gadolinium mixed oxide phosphor. The europium (Eu3+) was used as rare earth dopant. The phosphor was prepared by chemical co-precipitation method according to the formula (Y2-x-yGdx) O3: Euy3+ (x=0.5; y=0.05). The photoluminescence emission spectrum of the prepared phosphor shows intense peaks in the red region at 615 nm for 5D0→7F2 transitions and the photoluminescence excitation spectra show a broad band located around 220-270 nm for the emission wavelength fixed at 615 nm. The thermoluminescence studies were carried out after irradiating the phosphor by gamma rays in the dose range from 100 Gy to 1 KGy. In the thermoluminescence glow curves, one single peak was observed at about 300 °C of which the intensity increases linearly in the studied dose range of gamma rays. The glow peak was deconvoluted by GlowFit program and the kinetic parameters associated with the deconvoluted peaks were calculated. The kinetic parameters were also calculated by various glow curve shape and heating rate methods.

Thermoluminescence kinetics of pyrite (FeS2)

NASA Astrophysics Data System (ADS)

Silverman, A. N.; Levy, P. W.; Kierstead, J. A.

Thermoluminescence of pyrite (FeS2) was investigated to study the kinetics of single peak glow curves. The material used normally exhibits one large and four small peaks. However a glow curve can be obtained with only the large single peak that is suitable for testing thermoluminescence kinetics. Glow curves from aliquots of a single natural pyrite crystal studied in detail contain two low intensity thermoluminescence (TL) peaks at approximately 90 and 250 C, and two chemiluminescence (CL) peaks at approximately 350 and 430 C. The CL peaks are largely removable by initially heating the sample chamber under vacuum, pumping through liquid nitrogen traps, and recording glow curves immediately after helium is introduced, procedures which reduce system contaminants that react with pyrite. The shape, the variation of the temperature of the peak maximum (T(sub max)) with dose, and the retrapping to recombination cross section ratio (sigma) of the large 250 C peak are better described by the general one trap (GOT) kinetic equation, the basic equation from which the 1st and 2nd order kinetic equations are obtained as special cases, than by the 1st and 2nd order equations.

Constricted glow discharge plasma source

DOEpatents

Anders, Andre; Anders, Simone; Dickinson, Michael; Rubin, Michael; Newman, Nathan

2000-01-01

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

Thermoluminescent properties of ZnS:Mn nanocrystalline powders.

PubMed

Ortiz-Hernández, Arturo Agustín; Méndez García, Víctor Hugo; Pérez Arrieta, María Leticia; Ortega Sígala, José Juan; Araiza Ibarra, José de Jesús; Vega-Carrillo, Héctor Rene; Falcony Guajardo, Ciro

2015-05-01

Thermoluminescent ZnS nanocrystals doped with Mn(2+) ions were synthesized by chemical co-precipitation method. From X-ray diffraction studies it was observed that the synthesized nanoparticles have cubic zinc blende structure with average sizes of about 40-50nm. Morphology was analyzed by TEM. Photoluminescence studies showed two transitions, one of them close to 396nm and other close to 598nm, which is enhanced with increasing dopant concentration, this behavior was also observed in the cathodoluminescence spectrum. The thermoluminescence gamma dose-response has linear behavior over dose range 5-100mGy, the glow curve structure shows two glow peaks at 436K and at 518K that were taken into account to calculate the kinetic parameters using the Computerized Glow Curve Deconvolution procedure. Copyright © 2015 Elsevier Ltd. All rights reserved.

Non-linear macro evolution of a dc driven micro atmospheric glow discharge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, S. F.; Zhong, X. X., E-mail: xxzhong@sjtu.edu.cn

2015-10-15

We studied the macro evolution of the micro atmospheric glow discharge generated between a micro argon jet into ambient air and static water. The micro discharge behaves similarly to a complex ecosystem. Non-linear behaviors are found for the micro discharge when the water acts as a cathode, different from the discharge when water behaves as an anode. Groups of snapshots of the micro discharge formed at different discharge currents are captured by an intensified charge-coupled device with controlled exposure time, and each group consisted of 256 images taken in succession. Edge detection methods are used to identify the water surfacemore » and then the total brightness is defined by adding up the signal counts over the area of the micro discharge. Motions of the water surface at different discharge currents show that the water surface lowers increasingly rapidly when the water acts as a cathode. In contrast, the water surface lowers at a constant speed when the water behaves as an anode. The light curves are similar to logistic growth curves, suggesting that a self-inhibition process occurs in the micro discharge. Meanwhile, the total brightness increases linearly during the same time when the water acts as an anode. Discharge-water interactions cause the micro discharge to evolve. The charged particle bomb process is probably responsible for the different behaviors of the micro discharges when the water acts as cathode and anode.« less

One-step preparation of nanostructured martite catalyst and graphite electrode by glow discharge plasma for heterogeneous electro-Fenton like process.

PubMed

Khataee, Alireza; Sajjadi, Saeed; Hasanzadeh, Aliyeh; Vahid, Behrouz; Joo, Sang Woo

2017-09-01

Natural Martite ore particles and graphite were modified by alternating current (AC) glow discharge plasma to form nanostructured catalyst and cathode electrode for using in the heterogeneous-electro Fenton-like (Het-EF-like) process. The performance of the plasma-treated martite (PTM) and graphite electrode (PTGE) was studied for the treatment of paraquat herbicide in a batch system. 85.78% degradation efficiency for 20 mg L -1 paraquat was achieved in the modified process under desired operational conditions (i.e. current intensity of 300 mA, catalyst amount of 1 g L -1 , pH = 6, and background electrolyte (Na 2 SO 4 ) concentration of 0.05 mol L -1 ) which was higher than the 41.03% for the unmodified one after 150 min of treatment. The ecofriendly modification of the martite particles and the graphite electrode, no chemical needed, low leached iron and milder operational pH were the main privileges of plasma utilization. Moreover, the degradation efficiency through the process was not declined after five repeated cycles at the optimized conditions, which proved the stability of the nanostructured PTM and PTGE in the long-term usage. The archived results exhibit this method is the first example of high efficient, cost-effective, and environment-friendly method for generation of nanostructured samples. Copyright © 2017 Elsevier Ltd. All rights reserved.

Electron density and temperature in an atmospheric-pressure helium diffuse dielectric barrier discharge from kHz to MHz

NASA Astrophysics Data System (ADS)

Boisvert, J.-S.; Stafford, L.; Naudé, N.; Margot, J.; Massines, F.

2018-03-01

Diffuse dielectric barrier discharges are generated over a very wide range of frequencies. According to the targeted frequency, the glow, Townsend-like, hybrid, Ω and RF-α modes are sustained. In this paper, the electrical characterization of the discharge cell together with an electrical model are used to estimate the electron density from current and voltage measurements for excitation frequencies ranging from 50 kHz to 15 MHz. The electron density is found to vary from 1014 to 1017 m-3 over this frequency range. In addition, a collisional-radiative model coupled with optical emission spectroscopy is used to evaluate the electron temperature (assuming Maxwellian electron energy distribution function) in the same conditions. The time and space-averaged electron temperature is found to be about 0.3 eV in both the low-frequency and high-frequency ranges. However, in the medium-frequency range, it reaches almost twice this value as the discharge is in the hybrid mode. The hybrid mode is similar to the atmospheric-pressure glow discharge usually observed in helium DBDs at low frequency with the major difference being that the plasma is continuously sustained and is characterized by a higher power density.

Evolving Our Evaluation of Lighting Environments Project

NASA Technical Reports Server (NTRS)

Terrier, Douglas; Clayton, Ronald; Clark, Toni Anne

2016-01-01

Imagine you are an astronaut on their 100th day of your three year exploration mission. During your daily routine to the small hygiene compartment of the spacecraft, you realize that no matter what you do, your body blocks the light from the lamp. You can clearly see your hands or your toes but not both! What were those design engineers thinking! It would have been nice if they could have made the walls glow instead! The reason the designers were not more innovative is that their interpretation of the system lighting requirements didn't allow them to be so! Currently, our interior spacecraft lighting standards and requirements are written around the concept of a quantity of light illuminating a spacecraft surface. The natural interpretation for the engineer is that a lamp that throws light to the surface is required. Because of certification costs, only one lamp is designed and small rooms can wind up with lamps that may be inappropriate for the room architecture. The advances in solid state light emitting technologies and optics for lighting and visual communication necessitates the evaluation of how NASA envisions spacecraft lighting architectures and how NASA uses industry standards for the design and evaluation of lighting system. Current NASA lighting standards and requirements for existing architectures focus on the separate ability of a lighting system to throw light against a surface or the ability of a display system to provide the appropriate visual contrast. Realization that these systems can be integrated is not realized. The result is that the systems are developed independent from one another and potential efficiencies that could be realized from borrowing from the concept of one technology and applying it for the purpose of the other does not occur. This project investigated the possibility of incorporating large luminous surface lamps as an alternative or supplement to overhead lighting. We identified existing industry standards for architectural luminous or brightness uniformity as part of a lighting system definition. The efficiency of the surface lighting technology was evaluated for uniformity and power consumption. Finally, the team investigated possible performance savings if the walls were made to glow via a self luminous surface system instead of creating brightness by use of direct lighting of a highly reflective diffuse surface.

Determination of the thickness of Al2O3 barriers in magnetic tunnel junctions

NASA Astrophysics Data System (ADS)

Buchanan, J. D. R.; Hase, T. P. A.; Tanner, B. K.; Hughes, N. D.; Hicken, R. J.

2002-07-01

The barrier thickness in magnetic spin-dependent tunnel junctions with Al2O3 barriers has been measured using grazing incidence x-ray reflectivity and by fitting the tunneling current to the Simmons model. We have studied the effect of glow discharge oxidation time on the barrier structure, revealing a substantial increase in Al2O3 thickness with oxidation. The greater thickness of barrier measured using grazing incidence x-ray reflectivity compared with that obtained by fitting current density-voltage to the Simmons electron tunneling model suggests that electron tunneling is localized to specific regions across the barrier, where the thickness is reduced by fluctuations due to nonconformal roughness.

Velocity persistence of Brownian particles generated in a glow discharge

NASA Astrophysics Data System (ADS)

Hurd, Alan J.; Ho, Pauline

1989-06-01

Quasielastic light scattering from Brownian particles in the rarefied environment of a glow discharge exhibits Gaussianlike intensity correlation functions owing to the long mean free paths of the particles. The shape of the correlation function depends on the particles' average thermal velocity and friction coefficient, which can be related to aggregate mass and structure, and indicates a crossover from kinetic to hydrodynamic behavior.

A Glowing Recommendation: A Project-Based Cooperative Laboratory Activity to Promote Use of the Scientific and Engineering Practices

ERIC Educational Resources Information Center

Carmel, Justin H.; Ward, Joseph S.; Cooper, Melanie M.

2017-01-01

One of the most mystifying products on the market for people at any age is the glow stick: a plastic tube that, when snapped, creates a flood of bright, brilliantly colored light without the use of electricity or significant production of heat. In this case, the chemiluminescence reaction also provides an exciting phenomenon through which we can…

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…

SWIR Sky Glow Imaging for Detection of Turbulence in the Upper Atmosphere: Postprint

DTIC Science & Technology

2010-01-01

TP-2010-1015 SWIR SKY GLOW IMAGING FOR DETECTION OF TURBULENCE IN THE UPPER... the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this...number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE (DD-MM-YYYY) 01-01-2010 2. REPORT TYPE Technical Paper 3. DATES COVERED

Analysis of the glow curve of SrB 4O 7:Dy compounds employing the GOT model

NASA Astrophysics Data System (ADS)

Ortega, F.; Molina, P.; Santiago, M.; Spano, F.; Lester, M.; Caselli, E.

2006-02-01

The glow curve of SrB 4O 7:Dy phosphors has been analysed with the general one trap model (GOT). To solve the differential equation describing the GOT model a novel algorithm has been employed, which reduces significantly the deconvolution time with respect to the time required by usual integration algorithms, such as the Runge-Kutta method.

Radiation damage and sensitization effects on thermoluminescence of LiF:Mg,Ti (TLD-700)

NASA Astrophysics Data System (ADS)

Farag, M. A.; Sadek, A. M.; Shousha, Hany. A.; El-Hagg, A. A.; Atta, M. R.; Kitis, G.

2017-09-01

The radiation damage effects and enhancement the thermoluminescence (TL) efficiency of LiF:Mg,Ti (TLD-700)dosimeters via sensitization method were discussed. Attempts to eliminate the effects of damage and sensitization were made using different types of annealing processes. The results showed that after irradiating the dosimeters with dose > 250 Gy of 60Co gamma source, damage effects were observed. The sensitivity of the total area under the curve was decreased by a factor of ∼0.5 after irradiation at a pre-test dose of 2 kGy. However, the effects of radiation damage on each glow-peak are different. The glow-peak 2 was the only peak that was not affected by the high-dose irradiation. It has been shown that the degree of the radiation damage effect is related to the maximum dose-response function, f(D)max of the glow-peak. In general, significant radiation damage effects were observed for the glow-peaks of high f(D)max . Post-irradiation anneal at 280 °C for 30 min causes dramatic effects on the shape of the glow-curve and as well as on the sensitivity of the dosimeters. An increasing by a factor of ∼35 in the sensitivity of the total area under the curve was observed at a pre-test dose of 2 kGy. Improving the sensitivity of peak 7 by a factor of∼22 was the dominant factor in increasing the sensitivity of the dosimeters. On the other hand, an increasing by factors of ∼2.5 and ∼4 was found for peaks 2 and 5 respectively. On the other hand, a decreasing by a factor ∼0.5 was observed for peaks 3 and 4. At pre-test dose levels >250 Gy, a very strange and high intensity tail was observed in the high-temperature region of the glow-curves. The readout anneal was not enough to remove this tail. While, the furnace anneal could eliminate the sensitization effects but not the radiation damage effects on the sensitivity of the dosimeters.

Exploring the pattern of blood donor beliefs in first-time, novice, and experienced donors: differentiating reluctant altruism, pure altruism, impure altruism, and warm glow.

PubMed

Ferguson, Eamonn; Atsma, Femke; de Kort, Wim; Veldhuizen, Ingrid

2012-02-01

Using constructs from the Theory of Planned Behavior and theories of altruism, this article explores how multiple motivations and beliefs for blood donation are clustered and change across the donor career. In so doing important distinctions, for blood donation, between impure altruism, pure altruism, and warm glow are explored. Measures of intentions, cognitive and affective attitudes, role merger, pure altruism, trust, self-efficacy, subjective and moral norms, and habit formation were assessed in a sample of 12,580 whole blood donors. Analyses showed that a distinction between first-time, novice (one to four donations), and experienced donors (five or more donations) is justified. Principal components analysis and confirmatory factor analytic Multiple-Indicator Multiple-Causal models were used to compare models across these groups. A cognition-behavior (CB) factor, including intentions, was common to all groups. First-time and novice donors were marked by a newly identified motivational factor: "reluctant altruism" (i.e., the motivation to donate because of a lack of trust in others). First-time donors exhibited an impure altruism factor whereas for experienced donors warm glow and pure altruism factors were observed. For first-time donors impure altruism and reluctant altruism were both associated with the CB factor in females and impure altruism only in males. For both sexes reluctant altruism was associated of the CB factor in novice donors and warm glow and pure altruism for experienced donors. New avenues for intervention are suggested by the emergence of reluctant altruism for novice donors and warm glow for experienced donors. The importance of distinguishing aspects of altruism is highlighted. © 2012 American Association of Blood Banks.

Light Pollution in Ultraviolet and Visible Spectrum: Effect on Different Visual Perceptions

PubMed Central

Solano Lamphar, Héctor Antonio; Kocifaj, Miroslav

2013-01-01

In general terms, lighting research has been focused in the development of artificial light with the purpose of saving energy and having more durable lamps. However, the consequences that artificial night lighting could bring to the human being and living organisms have become an important issue recently. Light pollution represents a significant problem to both the environment and human health causing a disruption of biological rhythms related not only to the visible spectrum, but also to other parts of the electromagnetic spectrum. Since the lamps emit across a wide range of the electromagnetic spectrum, all photobiological species may be exposed to another type of light pollution. By comparing five different lamps, the present study attempts to evaluate UV radiative fluxes relative to what humans and two species of insects perceive as sky glow level. We have analyzed three atmospheric situations: clear sky, overcast sky and evolving precipitable water content. One important finding suggests that when a constant illuminance of urban spaces has to be guaranteed the sky glow from the low pressure sodium lamps has the most significant effect to the visual perception of the insects tested. But having the fixed number of luminaires the situation changes and the low pressure sodium lamp would be the best choice for all three species. The sky glow effects can be interpreted correctly only if the lamp types and the required amount of scotopic luxes at the ground are taken into account simultaneously. If these two factors are combined properly, then the ecological consequences of sky glow can be partly reduced. The results of this research may be equally useful for lighting engineers, architects, biologists and researchers who are studying the effects of sky glow on humans and biodiversity. PMID:23441205

Light pollution in ultraviolet and visible spectrum: effect on different visual perceptions.

PubMed

Solano Lamphar, Héctor Antonio; Kocifaj, Miroslav

2013-01-01

In general terms, lighting research has been focused in the development of artificial light with the purpose of saving energy and having more durable lamps. However, the consequences that artificial night lighting could bring to the human being and living organisms have become an important issue recently. Light pollution represents a significant problem to both the environment and human health causing a disruption of biological rhythms related not only to the visible spectrum, but also to other parts of the electromagnetic spectrum. Since the lamps emit across a wide range of the electromagnetic spectrum, all photobiological species may be exposed to another type of light pollution. By comparing five different lamps, the present study attempts to evaluate UV radiative fluxes relative to what humans and two species of insects perceive as sky glow level. We have analyzed three atmospheric situations: clear sky, overcast sky and evolving precipitable water content. One important finding suggests that when a constant illuminance of urban spaces has to be guaranteed the sky glow from the low pressure sodium lamps has the most significant effect to the visual perception of the insects tested. But having the fixed number of luminaires the situation changes and the low pressure sodium lamp would be the best choice for all three species. The sky glow effects can be interpreted correctly only if the lamp types and the required amount of scotopic luxes at the ground are taken into account simultaneously. If these two factors are combined properly, then the ecological consequences of sky glow can be partly reduced. The results of this research may be equally useful for lighting engineers, architects, biologists and researchers who are studying the effects of sky glow on humans and biodiversity.

The Development of a Method to Extract High Purity Oxygen From the Martian Atmosphere

NASA Astrophysics Data System (ADS)

Wu, Dongchuan

1994-01-01

A glow-discharge in an ambient Mars atmosphere (total pressure of 5 torr, composed of 96% carbon dioxide) results in the dissociation of carbon dioxide molecules into carbon monoxide and oxygen. If the glow-discharge cone is maintained adjacent and close to a silver membrane, operated at temperatures above 400 deg. C, atomic and molecular oxygen, produced by the glow-discharge, can be separated from the other species by atomic diffusion through the membrane to an ultrahigh vacuum region where the desorbed O2 is then collected. Experiments have been conducted to study the behavior of the glow discharge in both molecular oxygen and carbon dioxide environments, and to study the interaction of atomic and molecular oxygen with silver. It was found that, with this geometry, more than 75% of the CO2 was dissociated into CO and O with only 5 mA discharge current and that the permeation flux increased linearly with discharge current. Only 0.65% of the generated atomic oxygen was adsorbed at the membrane because it quickly recombined to form O2 as it migrated toward the membrane. The atomic oxygen arriving at the membrane, bypassed the thermal dissociative adsorption and therefore had a much higher sticking coefficient. This higher sticking coefficient resulted in a greatly increased surface concentration of oxygen which greatly increased the oxygen flux through the membrane. The sticking coefficient of the atomic oxygen on silver was estimated by using a Langmuir type model and was found to be close to 1 at room temperature. Since most of the gas phase atomic oxygen quickly recombined to form O2 as it migrated toward the silver membrane, both a small amount of atomic oxygen and a relative large amount of molecular oxygen components will adsorb on the hot Ag membrane. But because of the much higher sticking coefficient for atomic oxygen on silver, the atomic component dominated the adsorption. It was also found that the oxygen flux through the Ag membranes is diffusion controlled and therefore proportional to the reciprocal of the membrane thickness. Supported pin hole free Ag membranes with thicknesses of 12 micro m have been developed in this work. Furthermore, a pin hole free Ag membrane that was grown by a combination of Ar ion bombardment assisted physical vapor deposition and intermediate burnishing with a thickness less than 1 micro m is being developed which will substantially improve the oxygen flux level. Thickness of 1 micro m will permit flux levels of at least 106 molecules/cm2s. With this flux level, less than 1.5 m2 membrane surface area would be needed to support an astronaut on a continual basis on the Mars surface. The results of this work show that this approach of producing oxygen from the CO2 Martian atmosphere can eliminate mechanical filtration, compression and high temperature heating of the Mars atmosphere proposed previously by electrochemical methods.

Thermoluminescence properties of gamma-irradiated nano-structure hydroxyapatite.

PubMed

Shafaei, M; Ziaie, F; Sardari, D; Larijani, M M

2016-02-01

The suitability of nano-structured hydroxyapatite (HAP) for use as a thermoluminescence dosimeter was investigated. HAP samples were synthesized using a hydrolysis method. The formation of nanoparticles was confirmed by X-ray diffraction and average particle size was estimated to be ~30 nm. The glow curve exhibited a peak centered at around 200 °C. The additive dose method was applied and this showed that the thermoluminescence (TL) glow curves follow first-order kinetics due to the non-shifting nature of Tm after different doses. The numbers of overlapping peaks and related kinetic parameters were identified from Tm -Tstop through computerized glow curve deconvolution methods. The dependence of the TL responses on radiation dose was studied and a linear dose response up to 1000 Gy was observed for the samples. Copyright © 2015 John Wiley & Sons, Ltd.

Isotope effects on desorption kinetics of hydrogen isotopes implanted into stainless steel by glow discharge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matsuyama, M.; Kondo, M.; Noda, N.

2015-03-15

In a fusion device the control of fuel particles implies to know the desorption rate of hydrogen isotopes by the plasma-facing materials. In this paper desorption kinetics of hydrogen isotopes implanted into type 316L stainless steel by glow discharge have been studied by experiment and numerical calculation. The temperature of a maximum desorption rate depends on glow discharge time and heating rate. Desorption spectra observed under various experimental conditions have been successfully reproduced by numerical simulations that are based on a diffusion-limited process. It is suggested, therefore, that desorption rate of a hydrogen isotope implanted into the stainless steel ismore » limited by a diffusion process of hydrogen isotope atoms in bulk. Furthermore, small isotope effects were observed for the diffusion process of hydrogen isotope atoms. (authors)« less

Fuel-Flexible Engines for Portable-Power Applications

DTIC Science & Technology

2009-05-31

military grade, JP8, respectively. Repeated testing procedures elucidated the need for better measurement and control of the glow plug intensity ...different fuels that are currently available for market consumption. While petroleum- based fuels are being tested in this research, the researchers are...0.8 210 15 TA4, TA7 Gasoline C8-H18 0.75 280 15.1 TA7 Light Diesel C8-H18 0.85 210 15 TA7 Medium Diesel C14-H30 0.85 210 15 TA7 Heavy Diesel C21-H44

Increasing Stabilized Performance Of Amorphous Silicon Based Devices Produced By Highly Hydrogen Diluted Lower Temperature Plasma Deposition.

DOEpatents

Li, Yaun-Min; Bennett, Murray S.; Yang, Liyou

1999-08-24

High quality, stable photovoltaic and electronic amorphous silicon devices which effectively resist light-induced degradation and current-induced degradation, are produced by a special plasma deposition process. Powerful, efficient single and multi-junction solar cells with high open circuit voltages and fill factors and with wider bandgaps, can be economically fabricated by the special plasma deposition process. The preferred process includes relatively low temperature, high pressure, glow discharge of silane in the presence of a high concentration of hydrogen gas.

Increased Stabilized Performance Of Amorphous Silicon Based Devices Produced By Highly Hydrogen Diluted Lower Temperature Plasma Deposition.

DOEpatents

Li, Yaun-Min; Bennett, Murray S.; Yang, Liyou

1997-07-08

High quality, stable photovoltaic and electronic amorphous silicon devices which effectively resist light-induced degradation and current-induced degradation, are produced by a special plasma deposition process. Powerful, efficient single and multi-junction solar cells with high open circuit voltages and fill factors and with wider bandgaps, can be economically fabricated by the special plasma deposition process. The preferred process includes relatively low temperature, high pressure, glow discharge of silane in the presence of a high concentration of hydrogen gas.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gordienko, V.A.; Dubinov, A.E.; Zhuravlev, S.S.

A new type of magnetic confinement system--a Galathea with a myxine in the shape of a convex polyhedron--is proposed. The system was modeled experimentally by passing an RF current through the myxine. On the one hand, the myxine acts as an inductor whose electric field ionizes the gas and, on the other, it acts as an RF magnetic confinement system. A steady-state plasma produced and confined in this system is almost spherical in shape. The electron density and specific (per unit volume) glow intensity of the plasma produced are found to be higher than those in conventional helical inductors.

Dynamic characteristics of electric discharge in liquid under ultrasonic cavitation

NASA Astrophysics Data System (ADS)

Bulychev, N. A.; Kazaryan, M. A.; Averyushkin, A. S.; Kirichenko, M. N.; Zakharyan, Robert; Chernov, A. A.

2018-04-01

The characteristics of electrical discharges in liquid media under the influence of intense ultrasonic vibrations are investigated and the difference in dynamic characteristics of discharges before cavitation and after cavitation begins. The experiments carried out during this work made it possible to establish that in a liquid in an intense ultrasonic field above the cavitation threshold there exists a special form of an electric discharge characterized by volumetric luminescence in the entire space between the electrodes and the current-voltage characteristic inherent in an anomalous glow discharge in a gas.

A simple kinetic model of a Ne-H2 Penning-plasma laser

NASA Astrophysics Data System (ADS)

Petrov, G. M.; Stefanova, M. S.; Pramatarov, P. M.

1995-09-01

A simple kinetic model of the Ne-H2 Penning-Plasma Laser (PPL) (NeI 585.3 nm) is proposed. The negative glow of a hollow cathode discharge at intermediate pressures is considered as the active medium. The balance equations for the upper and lower laser levels, electrons, ions and electron energy are solved. The dependences of the laser gain on the discharge conditions (Ne and H2 partial pressures, discharge current) are calculated and measured. The calculated values are in a good agreement with the experimental data.

Zenith angle dependence of the geocoronal Lyman-alpha glow.

NASA Technical Reports Server (NTRS)

Paresce, F.; Kumar, S.; Bowyer, S.

1972-01-01

Review of the observations made on the zenith angle dependence and intensity of the geocoronal hydrogen Lyman-alpha glow by means of one of four extreme ultraviolet photometers flown to an altitude of 264 km on a Nike Tomahawk rocket launched from Thumba, India, in March 1970. The results obtained are compared with Meier and Mange's (1970) theoretical predictions. The possible causes for the discrepancies found are discussed.

Wavelength Scanning with a Tilting Interference Filter for Glow-Discharge Elemental Imaging.

PubMed

Storey, Andrew P; Ray, Steven J; Hoffmann, Volker; Voronov, Maxim; Engelhard, Carsten; Buscher, Wolfgang; Hieftje, Gary M

2017-06-01

Glow discharges have long been used for depth profiling and bulk analysis of solid samples. In addition, over the past decade, several methods of obtaining lateral surface elemental distributions have been introduced, each with its own strengths and weaknesses. Challenges for each of these techniques are acceptable optical throughput and added instrumental complexity. Here, these problems are addressed with a tilting-filter instrument. A pulsed glow discharge is coupled to an optical system comprising an adjustable-angle tilting filter, collimating and imaging lenses, and a gated, intensified charge-coupled device (CCD) camera, which together provide surface elemental mapping of solid samples. The tilting-filter spectrometer is instrumentally simpler, produces less image distortion, and achieves higher optical throughput than a monochromator-based instrument, but has a much more limited tunable spectral range and poorer spectral resolution. As a result, the tilting-filter spectrometer is limited to single-element or two-element determinations, and only when the target spectral lines fall within an appropriate spectral range and can be spectrally discerned. Spectral interferences that result from heterogeneous impurities can be flagged and overcome by observing the spatially resolved signal response across the available tunable spectral range. The instrument has been characterized and evaluated for the spatially resolved analysis of glow-discharge emission from selected but representative samples.

Elimination of stick-slip of elastomeric sutures by radiofrequency glow discharge deposited coatings.

PubMed

Griesser, H J; Chatelier, R C; Martin, C; Vasic, Z R; Gengenbach, T R; Jessup, G

2000-01-01

Fine elastomeric sutures intended for cardiovascular surgery can exhibit "stick-slip" behavior as they are pulled through tissue; the resulting oscillatory force can damage delicate tissue or cause sutures to snap. To eliminate this undesirable effect, sutures were surface-modified using a radiofrequency glow discharge in a vapor of either hexamethyldisiloxane or hexamethyldisilazane, to produce a thin polymeric coating on the suture. The same coatings were also deposited onto aluminized tape to facilitate their characterization by measurement of air/water contact angles and by X-ray photoelectron spectroscopy. Coatings from both monomers were found to be very hydrophobic. The hexamethyldisiloxane glow discharge coatings underwent negligible oxidation when stored in air, and thus remained stable over a shelf-life period akin to what may be required of sutures. The hexamethyldisilazane glow discharge coatings, in contrast, incorporated substantial amounts of oxygen over a 3-month period. The coatings did not measurably alter the tensile properties of the sutures. The frictional properties of coated sutures were assessed by measuring the dynamic friction between the suture and ovine myocardium. Both coatings were effective in removing the inherent stick-slip behavior of polybutester sutures in this model. The coatings remained intact after several passes and proved to be robust and efficacious under various strain regimes. Copyright 2000 John Wiley & Sons, Inc.

Thermoluminescence of contaminating minerals for the detection of radiation treatment of dried fruits

NASA Astrophysics Data System (ADS)

Khan, H. M.; Bhatti, Ijaz A.; Delincée, Henry

2002-03-01

Several types of dry fruits (pistachio nut, dried apricot, almond and raisins) have been investigated for detection of their radiation treatment by gamma rays or electron beam using thermoluminescence (TL) measurements. These samples were irradiated to 1.0-3.0 kGy (gamma rays) or 0.75-3.9 kGy (10 MeV electron beam). Thermoluminescence glow curves for the contaminating minerals separated from the dry fruits were recorded between the temperature range of 50°C and 500°C. In all the cases, the intensity of TL signal for the irradiated dry fruits was 1-3 orders of magnitudes higher than the TL intensity of the corresponding unirradiated control samples allowing clear distinction between the irradiated and unirradiated samples. These results were normalized by re-irradiating the mineral grains with a gamma-ray dose of 1.0 kGy, and a second glow curve was recorded. The ratio of intensity of the first glow curve (TL 1) to that after the normalization dose (TL 2), i.e. (TL 1/TL 2) was determined and compared with the recommended threshold values. These parameters, together with comparison of the shape of the first glow curve, gave unequivocal results about the radiation treatment of the dry fruit samples.

Adherence to hydroxyurea medication by children with sickle cell disease (SCD) using an electronic device: a feasibility study.

PubMed

Inoue, Susumu; Kodjebacheva, Gergana; Scherrer, Tammy; Rice, Gary; Grigorian, Matthew; Blankenship, Jeremy; Onwuzurike, Nkechi

2016-08-01

Adherence to hydroxyurea (HU) is a significant modifying factor in sickle cell vaso-occlusive pain. We conducted a study using an electronic medication container-monitor-reminder device (GlowCap™) to track adherence and determine whether use of this device affected rates of HU adherence. Subjects were regular attendees to our clinic. They were given a 37-item questionnaire and were asked to use a GlowCap containing HU. When the device cap is opened, it makes a remote "medication taken" record. The device also provides usage reminder in the form of lights and alarm sounds if the cap opening is delayed. Nineteen subjects participated in the survey, and 17 in the intervention phase. Of the 17, 12 had reliable adherence data. Seventeen caregivers of patients and two patients completed the survey. Two most common barriers to adherence identified were lack of reminders and absence of medicine home delivery. The intervention component of this study, which used both the electronic (GlowCap) method and medication possession ratio showed that the median adherence rate for the 12 patients evaluated was 85 %. The GlowCap device accurately kept a record of adherence rates. This device may be an effective tool for increasing HU medication adherence.

Effect of annealing temperature and dopant concentration on the thermoluminescence sensitivity in LiF:Mg,Cu,Ag material.

PubMed

Yahyaabadi, Akram; Torkzadeh, Falamarz; Rezaei Ochbelagh, Dariush; Hosseini Pooya, Seyed Mahdi

2018-04-24

LiF:Mg,Cu,Ag is a new dosimetry material that is similar to LiF:Mg,Cu,P in terms of dosimetric properties. The effect of the annealing temperature in the range of 200 to 350°C on the thermoluminescence (TL) sensitivity and the glow curve structure of this material at different concentrations of silver (Ag) was investigated. It has been demonstrated that the optimum values of the annealing temperature and the Ag concentration are 240°C and 0.1 mol% for better sensitivity, respectively. The TL intensity decreases at annealing temperatures lower than 240°C or higher than 240°C, reaching a minimum at 300°C and then again increases for various Ag concentrations. It was observed that the glow curve structure altered and the area under the low temperature peak as well as the area under the main dosimetric peak decreased with increasing annealing temperature. The position of the main dosimetric peak moved in the direction of higher temperatures, but at 320 and 350°C annealing temperatures, it shifted to lower temperatures. It was also observed that the TL sensitivity could partially be recovered by a combined annealing procedure. Copyright © 2018 John Wiley & Sons, Ltd.

An ion source for radiofrequency-pulsed glow discharge time-of-flight mass spectrometry

NASA Astrophysics Data System (ADS)

González Gago, C.; Lobo, L.; Pisonero, J.; Bordel, N.; Pereiro, R.; Sanz-Medel, A.

2012-10-01

A Grimm-type glow discharge (GD) has been designed and constructed as an ion source for pulsed radiofrequency GD spectrometry when coupled to an orthogonal time of flight mass spectrometer. Pulse shapes of argon species and analytes were studied as a function of the discharge conditions using a new in-house ion source (UNIOVI GD) and results have been compared with a previous design (PROTOTYPE GD). Different behavior and shapes of the pulse profiles have been observed for the two sources evaluated, particularly for the plasma gas ionic species detected. In the more analytically relevant region (afterglow), signals for 40Ar+ with this new design were negligible, while maximum intensity was reached earlier in time for 41(ArH)+ than when using the PROTOTYPE GD. Moreover, while maximum 40Ar+ signals measured along the pulse period were similar in both sources, 41(ArH)+ and 80(Ar2)+ signals tend to be noticeable higher using the PROTOTYPE chamber. The UNIOVI GD design was shown to be adequate for sensitive direct analysis of solid samples, offering linear calibration graphs and good crater shapes. Limits of detection (LODs) are in the same order of magnitude for both sources, although the UNIOVI source provides slightly better LODs for those analytes with masses slightly higher than 41(ArH)+.

Liquid Sampling-Atmospheric Pressure Glow Discharge (LS-APGD) Ionization Source for Elemental Mass Spectrometry: Preliminary Parametric Evaluation and Figures of Merit

DOE Office of Scientific and Technical Information (OSTI.GOV)

Quarles, C. Derrick; Carado, Anthony J.; Barinaga, Charles J.

2012-01-01

A new, low power ionization source for the elemental analysis of aqueous solutions has recently been described. The liquid sampling-atmospheric pressure glow discharge (LS-APGD) source operates at relatively low currents (<20 mA) and solution flow rates (<50 μL min-1), yielding a relatively simple alternative for atomic mass spectrometry applications. The LS-APGD has been interfaced to what is otherwise an organic, LC-MS mass analyzer, the Thermo Scientific Exactive Orbitrap without any modifications; other than removing the electrospray ionization (ESI) source supplied with that instrument. A glow discharge is initiated between the surface of the test solution exiting a glass capillary andmore » a metallic counter electrode mounted at a 90° angle and separated by a distance of ~5 mm. As with any plasma-based ionization source, there are key discharge operation and ion sampling parameters that affect the intensity and composition of the derived mass spectra; including signal-to-background ratios. We describe here a preliminary parametric evaluation of the roles of discharge current, solution flow rate, argon sheath gas flow rate, and ion sampling distance as they apply on this mass analyzer system. A cursive evaluation of potential matrix effects due to the presence of easily ionized elements (EIEs) indicate that sodium concentrations of up to 500 μg mL-1 generally cause suppressions of less than 50%, dependant upon the analyte species. Based on the results of this series of studies, preliminary limits of detection (LOD) have been established through the generation of calibration functions. Whilst solution-based concentrations LOD levels of 0.02 – 2 μg mL-1 3 are not impressive on the surface, the fact that they are determined via discrete 5 μL injections leads to mass-based detection limits at picogram to singlenanogram levels. The overhead costs associated with source operation (10 W d.c. power, solution flow rates of <50 μL min-1, and gas flow rates <10 mL min-1) are very attractive. While further optimization in the source design is suggested here, it is believed that the LS-APGD ion source may present a practical alternative to inductively-coupled plasma (ICP) sources typically employed in elemental mass spectrometry.« less

Ring Around the Black Hole

NASA Technical Reports Server (NTRS)

Wanjek, Christopher

2003-01-01

Regardless of size, black holes easily acquire accretion disks. Supermassive black holes can feast on the bountiful interstellar gas in galactic nuclei. Small black holes formed from collapsing stars often belong to binary systems in which a bulging companion star can spill some of its gas into the black hole s reach. In the chaotic mess of the accretion disk, atoms collide with one another. Swirling plasma reaches speeds upward of 10% that of light and glows brightly in many wavebands, particularly in X-rays. Gas gets blown back by a wind of radiation from the inner disk. New material enters the disks from different directions.

KSC-06pd2006

NASA Image and Video Library

2006-08-29

KENNEDY SPACE CENTER, FLA. - Space Shuttle Atlantis is hard down on the launch pad after rolling back to Launch Pad 39B. The Atlantic Ocean and lagoon water in the background reflect the glowing light of a setting sun. The shuttle had been moved off the launch pad due to concerns about the impact of Tropical Storm Ernesto, expected within 24 hours. The forecast of lesser winds expected from Ernesto and its projected direction convinced Launch Integration Manager LeRoy Cain and Shuttle Launch Director Mike Leinbach to return the shuttle to the launch pad. Photo credit: NASA/Kim Shiflett

A dc non-thermal atmospheric-pressure plasma microjet

NASA Astrophysics Data System (ADS)

Zhu, WeiDong; Lopez, Jose L.

2012-06-01

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

Material Science

NASA Image and Video Library

2003-05-05

As easy to read as a home pregnancy test, three Quantifiable Lateral Flow Assay (QLFA) strips used to test water for E. coli show different results. The brightly glowing control line on the far right of each strip indicates that all three tests ran successfully. But the glowing test line on the middle left and bottom strips reveal their samples were contaminated with E. coli bacteria at two different concentrations. The color intensity correlates with concentration of contamination.

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.

The Properties of Fluorine, Oxygen Bifluoride, and Chlorine Trifluoride

DTIC Science & Technology

1949-09-06

they should be of forg€;d steel. Welded joints are excellent provided the welds are slag -free. Cast iron or any ether material containing silica cannot...400°C brilliant light Manganese powder form; 500°C formation of fluoride with glowing Zinc Cadmium powder form; heating glowing and flashing...reaction upon heating Magnesium at first, no reaction; explosive reaction Aluminum after ignition with carbon Zinc TV „ 1X11 Lead Cupfier L

Comparison of the observed and calculated coherent forward scattering spectra of the 842.5 nm Ar I and 844.6 nm O I lines in a radio frequency glow discharge

NASA Astrophysics Data System (ADS)

Matsuta, Hideyuki

2017-06-01

The coherent forward scattering (CFS) spectra of O I 844.6 nm and Ar I 842.5 nm lines in a radio frequency (RF) glow discharge were measured using a CFS spectrometer that functions in the Faraday configuration with permanent double-ring magnets and a diode-laser source. A significant change in the CFS spectrum of the Ar I 842.5 nm line was observed when the partial pressures of argon in a Hesbnd Ar RF glow discharge were changed . Based on the theoretical calculations of the CFS spectra performed using Faraday functions, a comparison between the observed and calculated spectra was performed. The CFS line profile of O I 844.6 nm and changes in the Ar I 842.5 nm CFS spectrum are explained by theoretical calculations.

Nighttime image dehazing using local atmospheric selection rule and weighted entropy for visible-light systems

NASA Astrophysics Data System (ADS)

Park, Dubok; Han, David K.; Ko, Hanseok

2017-05-01

Optical imaging systems are often degraded by scattering due to atmospheric particles, such as haze, fog, and mist. Imaging under nighttime haze conditions may suffer especially from the glows near active light sources as well as scattering. We present a methodology for nighttime image dehazing based on an optical imaging model which accounts for varying light sources and their glow. First, glow effects are decomposed using relative smoothness. Atmospheric light is then estimated by assessing global and local atmospheric light using a local atmospheric selection rule. The transmission of light is then estimated by maximizing an objective function designed on the basis of weighted entropy. Finally, haze is removed using two estimated parameters, namely, atmospheric light and transmission. The visual and quantitative comparison of the experimental results with the results of existing state-of-the-art methods demonstrates the significance of the proposed approach.

Thermoluminescence analysis can identify irradiated ingredient in soy sauce before and after pasteurization

NASA Astrophysics Data System (ADS)

Lee, Jeong-Eun; Sanyal, Bhaskar; Akram, Kashif; Jo, Yunhee; Baek, Ji-Yeong; Kwon, Joong-Ho

2017-05-01

Thermoluminescence (TL) analysis was conducted to identify small quantities (0.5%, 1%, and 1.5%) of γ ray-or electron beam-irradiated garlic powder in a soy sauce after commercial pasteurization. The sauce samples with γ ray- and electron beam-irradiated (0, 1 or 10 kGy) garlic powder showed detectable TL glow curves, characterized by radiation-induced maximum in the temperature range of 180-225 °C. The successful identification of soy sauces with an irradiation history was dependent on both the mixing ratio of the irradiated ingredient and the irradiation dose. Post-irradiation pasteurization (85 °C, 30 min) caused no considerable changes in TL glow shape or intensity. Interlaboratory tests demonstrated that the shape and intensity of the first TL glow curve (TL1) could be a better detection marker than a TL ratio (TL1/TL2).

Bacterial bioluminescence as a lure for marine zooplankton and fish.

PubMed

Zarubin, Margarita; Belkin, Shimshon; Ionescu, Michael; Genin, Amatzia

2012-01-17

The benefits of bioluminescence for nonsymbiotic marine bacteria have not been elucidated fully. One of the most commonly cited explanations, proposed more than 30 y ago, is that bioluminescence augments the propagation and dispersal of bacteria by attracting fish to consume the luminous material. This hypothesis, based mostly on the prevalence of luminous bacteria in fish guts, has not been tested experimentally. Here we show that zooplankton that contacts and feeds on the luminescent bacterium Photobacterium leiognathi starts to glow, and demonstrate by video recordings that glowing individuals are highly vulnerable to predation by nocturnal fish. Glowing bacteria thereby are transferred to the nutritious guts of fish and zooplankton, where they survive digestion and gain effective means for growth and dispersal. Using bioluminescence as bait appears to be highly beneficial for marine bacteria, especially in food-deprived environments of the deep sea.

Bacterial bioluminescence as a lure for marine zooplankton and fish

PubMed Central

Zarubin, Margarita; Belkin, Shimshon; Ionescu, Michael; Genin, Amatzia

2012-01-01

The benefits of bioluminescence for nonsymbiotic marine bacteria have not been elucidated fully. One of the most commonly cited explanations, proposed more than 30 y ago, is that bioluminescence augments the propagation and dispersal of bacteria by attracting fish to consume the luminous material. This hypothesis, based mostly on the prevalence of luminous bacteria in fish guts, has not been tested experimentally. Here we show that zooplankton that contacts and feeds on the luminescent bacterium Photobacterium leiognathi starts to glow, and demonstrate by video recordings that glowing individuals are highly vulnerable to predation by nocturnal fish. Glowing bacteria thereby are transferred to the nutritious guts of fish and zooplankton, where they survive digestion and gain effective means for growth and dispersal. Using bioluminescence as bait appears to be highly beneficial for marine bacteria, especially in food-deprived environments of the deep sea. PMID:22203999

Analysis Of The Different Zones Of Glow Discharge Of Ethyl Alcohol (C2H6O)

NASA Astrophysics Data System (ADS)

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

2014-05-01

The aim of this work is to explore the emission spectroscopy of ethyl alcohol in some regions, also is determine the result elements of the glow discharge, the spectrums were observed in a range of 200 at 1100 nm in the different zones inside of the tube at different distances of 20 and 30 cm. The elements are: in anode region C6H5 (483.02nm), CHO (519.56nm) and H2 (560.47nm), in the positive column CO2+ (315.52 y 337.00nm), O+ (357.48nm), CH+ (380.61nm) and CO+ (399.73nm); in the cathode region we observed O+ (391.19nm), CHOCHO (428.00nm), CO+ (471.12nm) and H2 (656.52nm). C6H5, CHO y H2 species occurring in all regions analyzed varying the glow discharge emission intensity.

Analysis of read-out heating rate effects on the glow peaks of TLD-100 using WinGCF software

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bauk, Sabar, E-mail: sabar@usm.my; Hussin, Siti Fatimah; Alam, Md. Shah

This study was done to analyze the effects of the read-out heating rate on the LiF:Mg,Ti (TLD-100) thermoluminescent dosimeters (TLD) glow peaks using WinGCF computer software. The TLDs were exposed to X-ray photons with a potential difference of 72 kVp and 200 mAs in air and were read-out using a Harshaw 3500 TLD reader. The TLDs were read-out using four read-out heating rates at 10, 7, 4 and 1 °C s{sup −1}. It was observed that lowering the heating rate could separate more glow peaks. The activation energy for peak 5 was found to be lower than that for peakmore » 4. The peak maximum temperature and the integral value of the main peak decreased as the heating rate decreases.« less

Method of enhancing the electronic properties of an undoped and/or N-type hydrogenated amorphous silicon film

DOEpatents

Carlson, David E.

1980-01-01

The dark conductivity and photoconductivity of an N-type and/or undoped hydrogenated amorphous silicon layer fabricated by an AC or DC proximity glow discharge in silane can be increased through the incorporation of argon in an amount from 10 to about 90 percent by volume of the glow discharge atmosphere which contains a silicon-hydrogen containing compound in an amount of from about 90 to about 10 volume percent.

Impact energy and retained dose uniformity in enhanced glow discharge plasma immersion ion implantation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Q. Y.; Fu, Ricky K. Y.; Chu, Paul K.

2009-08-10

The implantation energy and retained dose uniformity in enhanced glow discharge plasma immersion ion implantation (EGD-PIII) is investigated numerically and experimentally. Depth profiles obtained from different samples processed by EGD-PIII and traditional PIII are compared. The retained doses under different pulse widths are calculated by integrating the area under the depth profiles. Our results indicate that the improvement in the impact energy and retained dose uniformity by this technique is remarkable.

The Growing Threat of Light Pollution to Ground-Based Observatories

NASA Astrophysics Data System (ADS)

Green, Richard F.; Luginbuhl, Christian; Wainscoat, Richard J.; Duriscoe, Dan

2018-01-01

With few exceptions, growing sky glow from artificial sources negatively impacts the sky background recorded at major observatories around the world. We report techniques for measuring night sky brightness and extracting the contribution of artificial sky glow at observatories and other protected sites. The increase in artificial ambient light and its changing spectrum with LED replacements is likely to be significant. A compendium of worldwide regulatory approaches to astronomical site protection gives insight on multiple effective strategies.

Laminar Instability and Transition on the X-51A

DTIC Science & Technology

2009-08-01

AIM15 controller. Surface thermocouples are affixed to the contraction by hose clamps and are used by the controllers to determine when each heater...installed in the model. One 20- gauge, braided , high-voltage wire is soldered to the inner electrode. This wire then passes through the model, angle...and another 20-gauge, braided , high-voltage wire leading from the sting to the ground of the glow electronics. From the back of the sting to the glow

Quantifiable Lateral Flow Assay Test Strips

NASA Technical Reports Server (NTRS)

2003-01-01

As easy to read as a home pregnancy test, three Quantifiable Lateral Flow Assay (QLFA) strips used to test water for E. coli show different results. The brightly glowing control line on the far right of each strip indicates that all three tests ran successfully. But the glowing test line on the middle left and bottom strips reveal their samples were contaminated with E. coli bacteria at two different concentrations. The color intensity correlates with concentration of contamination.

Clostridium beijerinckii mutant obtained atmospheric pressure glow discharge generates enhanced electricity in a microbial fuel cell.

PubMed

Liu, Jun; Guo, Ting; Wang, Dong; Ying, Hanjie

2015-01-01

A Clostridium beijerinckii mutant M13 was derived from C. beijerinckii NCIMB 8052 by atmospheric pressure glow discharge. C. beijerinckii M13 generated a maximum output power density of 79.2 mW m(-2) and a maximum output voltage of 230 mV in a microbial fuel cell containing 1 g glucose l(-1) as carbon source and 0.15 g methyl viologen l(-1) as an electron carrier.

Space shuttle ram glow: Implication of NO2 recombination continuum

NASA Technical Reports Server (NTRS)

Swenson, G. R.; Mende, S. B.; Clifton, S.

1985-01-01

The ram glow data gathered to data from imaging experiments on space shuttle suggest the glow is a continuum (within 34 angstrom resolution); the continuum shape is such that the peak is near 7000 angstroms decreasing to the blue and red, and the average molecular travel leading to emission after leaving the surface is 20 cm (assuming isotropic scattering from the surface). Emission continuum is rare in molecular systems but the measured spectrum does resemble the laboratory spectrum of NO2 (B) recombination continuum. The thickness of the observed emission is consistent with the NO2 hypothesis given an exit velocity of approx. 2.5 km/sec (1.3 eV) which leaves approx. 3.7 eV of ramming OI energy available for unbonding the recombined NO2 from the surface. The NO2 is formed in a 3-body recombination of OI + NO + m = NO2 + m where OI originates from the atmosphere and NO is chemically formed on the surface from atmospheric NI and OI. The spacecraft surface then acts as the n for the reaction: Evidence exists from orbital mass spectrometer data that the NO and NO2 chemistry described in this process does occur on surfaces of spectrometer orifices in orbit. Surface temperature effects are likely a factor in the NO sticking efficiency and, therefore, glow intensities.

Space shuttle Ram glow: Implication of NO2 recombination continuum

NASA Astrophysics Data System (ADS)

Swenson, G. R.; Mende, S. B.; Clifton, S.

1985-09-01

The ram glow data gathered to data from imaging experiments on space shuttle suggest the glow is a continuum (within 34 angstrom resolution); the continuum shape is such that the peak is near 7000 angstroms decreasing to the blue and red, and the average molecular travel leading to emission after leaving the surface is 20 cm (assuming isotropic scattering from the surface). Emission continuum is rare in molecular systems but the measured spectrum does resemble the laboratory spectrum of NO2 (B) recombination continuum. The thickness of the observed emission is consistent with the NO2 hypothesis given an exit velocity of approx. 2.5 km/sec (1.3 eV) which leaves approx. 3.7 eV of ramming OI energy available for unbonding the recombined NO2 from the surface. The NO2 is formed in a 3-body recombination of OI + NO + m = NO2 + m where OI originates from the atmosphere and NO is chemically formed on the surface from atmospheric NI and OI. The spacecraft surface then acts as the n for the reaction: Evidence exists from orbital mass spectrometer data that the NO and NO2 chemistry described in this process does occur on surfaces of spectrometer orifices in orbit. Surface temperature effects are likely a factor in the NO sticking efficiency and, therefore, glow intensities.

Investigation of a Mercury-Argon Hot Cathode Discharge

NASA Astrophysics Data System (ADS)

Wamsley, Robert Charles

Classical absorption and laser induced fluorescence (LIF) experiments are used to investigate processes in the cathode region of a Hg-Ar hot cathode discharge. The absorption and LIF measurements are used to test the qualitative understanding and develop a quantitative model of a hot cathode discharge. The main contribution of this thesis is a model of the negative glow region that demonstrates the importance of Penning ionization to the ionization balance in the negative glow. We modeled the excited argon balance equation using a Monte Carlo simulation. In this simulation we used the trapped radiative decay rate of the resonance levels and the Penning ionization rate as the dominant loss terms in the balance equation. The simulated data is compared to and found to agree with absolute excited argon densities measured in a classical absorption experiment. We found the primary production rate per unit volume of excited Ar atoms in the simulation is sharply peaked near the cathode hot spot. We used the ion production rate from this simulation and a Green's function solution to the ambipolar diffusion equation to calculate the contribution of Penning ionization to the total ion density. We compared the results of this calculation to our experimental values of the Hg ^+ densities in the negative glow. We found that Penning ionization is an important and possibly the dominant ionization process in the negative glow.

Transition rate diagrams - A new approach to the study of selective excitation processes: The spectrum of manganese in a Grimm-type glow discharge

NASA Astrophysics Data System (ADS)

Weiss, Zdeněk; Steers, Edward B. M.; Pickering, Juliet C.; Mushtaq, Sohail

2014-02-01

The emission spectra of manganese observed using a Grimm-type glow discharge in pure argon, argon with 0.3% v/v hydrogen and pure neon were studied in order to identify major excitation and ionization processes of manganese in the plasma. A new procedure is proposed, in which each observed emission line is associated with the corresponding transition between different states of the Mn atom or Mn ion, and, by considering all the observed transitions from and into a specific state, a measure of the total rate is determined at which this state is radiatively populated and depopulated. These resulting population/depopulation rates are then plotted as function of level energy. Such plots, called here “transition rate diagrams”, show the role of individual states in the formation of the observed spectrum and can be used to identify possible selective excitation processes. Also, cascade excitation by radiative decay of higher excited states can be conveniently evaluated in this way. A detailed description of the observed Mn I and Mn II spectra is given for Ar, Ar-H2 and Ne plasmas and relevant excitation/ionization mechanisms are discussed. Matrix effects in analysis of manganese by glow discharge spectroscopy are discussed. A list of important Mn I and Mn II lines excited in the glow discharge plasma is given.

Thermoluminescent response of LiF (TLD-100) to 5-30 keV electrons and the effect of annealing in various atmospheres.

PubMed

Lasky, J B; Moran, P R

1977-09-01

The response of single crystal and extruded ribbons of TLD-100 to 5-30 keV electrons was investigated. If annealing is done in a vacuum, the sensitivity of TLD-100 single crystals to these electrons and the resultant glow curve are essentially the same as when irradiation are carried out with 137Cs gamma rays. All discrepancies in sensitivity can then be accounted for by the higher LET of electrons. The commonly used 'standard annealing' at 400 degrees C for one hour produced a change in the glow curve shape and a loss in sensitivity in contrast to the vacuum anneal results. Diffusion of hydroxyl ions into the sample during air annealing is believed to be the primary cause for this change. These results explain the source of the 'dead layer' proposed to explain the variation with particle size of the luminescent efficiency of X-ray irradiated TLD-100 powder and the low TL efficiency from low energy electron irradiations. With the use of the vacuum annealing procedure, the same sensitivity and reproducibility can be achieved for the dosimetry of low energy electrons and other shallowly penetrating radiation as is currently achieved for the dosimetry of X-rays.

Glow discharge sources for atomic and molecular analyses

NASA Astrophysics Data System (ADS)

Storey, Andrew Patrick

Two types of glow discharges were used and characterized for chemical analysis. The flowing atmospheric pressure afterglow (FAPA) source, based on a helium glow discharge (GD), was utilized to analyze samples with molecular mass spectrometry. A second GD, operated at reduced pressure in argon, was employed to map the elemental composition of a solid surface with novel optical detection systems, enabling new applications and perspectives for GD emission spectrometry. Like many plasma-based ambient desorption-ionization sources being used around the world, the FAPA requires a supply of helium to operate effectively. With increased pressures on global helium supply and pricing, the use of an interrupted stream of helium for analysis was explored for vapor and solid samples. In addition to the mass spectra generated by the FAPA source, schlieren imaging and infrared thermography were employed to map the behavior of the source and its surroundings under the altered conditions. Additionally, a new annular microplasma variation of the FAPA source was developed and characterized. A spectroscopic imaging system that utilized an adjustable-tilt interference filter was used to map the elemental composition of a sample surface by glow discharge emission spectroscopy. This apparatus was compared to other GD imaging techniques for mapping elemental surface composition. The wide bandpass filter resulted in significant spectral interferences that could be partially overcome with chemometric data processing. Because time-resolved GD emission spectroscopy can provide fine depth-profiling measurements, a natural extension of GD imaging would be its application to three-dimensional characterization of samples. However, the simultaneous cathodic sputtering that occur across the sample results in a sampling process that is not completely predictable. These issues are frequently encountered when laterally varied samples are explored with glow discharge imaging techniques. These insights are described with respect to their consequences for both imaging and conventional GD spectroscopic techniques.

Thermoluminescence and glow curves analysis of γ-exposed Eu{sup 3+} doped K{sub 3}Y(PO{sub 4}){sub 2} nanophosphors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gupta, Palvi; Bedyal, A.K.; Kumar, Vinay, E-mail: vinaykdhiman@yahoo.com

2016-01-15

Highlights: • First time, a detailed comparative study of the glow curves and kinetic parameters was made on K{sub 3}Y(PO{sub 4}){sub 2} nanophosphor. • Combustion method was employed to synthesize the Eu{sup 3+} doped K{sub 3}Y(PO{sub 4}){sub 2} nanophosphor. • The nanophosphor exhibited sublinear response suggesting that it is suitable for TL dosimetry. - Abstract: Eu{sup 3+} doped K{sub 3}Y(PO{sub 4}){sub 2} nanophosphor was synthesized by combustion synthesis using urea as a fuel. The crystal structure and particle morphology of the nanophosphor were investigated by using X-ray diffraction and transmission electron microscopy, respectively. A Thermoluminescence (TL) study was carried outmore » after exposing the samples to gamma radiation. The TL glow curves exhibited a prominent peak at 407 K and a small hump at 478 K. The intensity of the peaks increased with the increase in the dose of the gamma rays (0.01–5 kGy). The K{sub 3}Y(PO{sub 4}){sub 2}: Eu{sup 3+} (2.5 mol%) nanophosphor exhibited sublinear TL response to γ-radiation over a wide range of gamma doses (0.01–5 kGy). The TLanal program was used to analyze the glow curves of the K{sub 3}Y(PO{sub 4}){sub 2} nanophosphor at different doses (0.2–5 kGy) and different heating rates (3–10 K/s). A comparative study was done for kinetic trapping parameters that were determined by the peak shape methods of Chen, Grossweiner and Lushchik. The frequency factors (s) for each glow peak were also calculated. The values of the activation energy (E) obtained by the TLanal program were in good agreement with those obtained by the peak shape methods. The effect of different amount of doses and different heating rates are discussed.« less

Cassini observations of Io's visible aurorae

USGS Publications Warehouse

Geissler, P.; McEwen, A.; Porco, C.; Strobel, D.; Saur, J.; Ajello, J.; West, R.

2004-01-01

More than 500 images of Io in eclipse were acquired by the Cassini spacecraft in late 2000 and early 2001 as it passed through the jovian system en route to Saturn (Porco et al., 2003, Science 299, 1541-1547). Io's bright equatorial glows were detected in Cassini's near-ultraviolet filters, supporting the interpretation that the visible emissions are predominantly due to molecular SO2. Detailed comparisons of laboratory SO2 spectra with the Cassini observations indicate that a mixture of gases contribute to the equatorial emissions. Potassium is suggested by new detections of the equatorial glows at near-infrared wavelengths from 730 to 800 nm. Neutral atomic oxygen and sodium are required to explain the brightness of the glows at visible wavelengths. The molecule S2 is postulated to emit most of the glow intensity in the wavelength interval from 390 to 500 nm. The locations of the visible emissions vary in response to the changing orientation of the external magnetic field, tracking the tangent points of the jovian magnetic field lines. Limb glows distinct from the equatorial emissions were observed at visible to near-infrared wavelengths from 500 to 850 nm, indicating that atomic O, Na, and K are distributed across Io's surface. Stratification of the atmosphere is demonstrated by differences in the altitudes of emissions at various wavelengths: SO2 emissions are confined to a region close to Io's surface, whereas neutral oxygen emissions are seen at altitudes that reach up to 900 km, or half the radius of the satellite. Pre-egress brightening demonstrates that light scattered into Jupiter's shadow by gases or aerosols in the giant planet's upper atmosphere contaminates images of Io taken within 13 minutes of entry into or emergence from Jupiter's umbra. Although partial atmospheric collapse is suggested by the longer timescale for post-ingress dimming than pre-egress brightening, Io's atmosphere must be substantially supported by volcanism to retain auroral emissions throughout the duration of eclipse. ?? 2004 Elsevier Inc. All rights reserved.

The application of the least squares finite element method to Abel's integral equation. [with application to glow discharge problem

NASA Technical Reports Server (NTRS)

Balasubramanian, R.; Norrie, D. H.; De Vries, G.

1979-01-01

Abel's integral equation is the governing equation for certain problems in physics and engineering, such as radiation from distributed sources. The finite element method for the solution of this non-linear equation is presented for problems with cylindrical symmetry and the extension to more general integral equations is indicated. The technique was applied to an axisymmetric glow discharge problem and the results show excellent agreement with previously obtained solutions

Computerised curve deconvolution of TL/OSL curves using a popular spreadsheet program.

PubMed

Afouxenidis, D; Polymeris, G S; Tsirliganis, N C; Kitis, G

2012-05-01

This paper exploits the possibility of using commercial software for thermoluminescence and optically stimulated luminescence curve deconvolution analysis. The widely used software package Microsoft Excel, with the Solver utility has been used to perform deconvolution analysis to both experimental and reference glow curves resulted from the GLOw Curve ANalysis INtercomparison project. The simple interface of this programme combined with the powerful Solver utility, allows the analysis of complex stimulated luminescence curves into their components and the evaluation of the associated luminescence parameters.

Schlieren Imaging and Pulsed Detonation Engine Testing of Ignition by a Nanosecond Repetitively Pulsed Discharge

DTIC Science & Technology

2016-05-16

in ethylene–air and aviation gasoline (avgas)–air mixtures. Testing of NRP discharges in the glow and corona regimes in PDE engines has been...in further detail in Refs. [17,21–23]. NRP discharges in the pin-to-pin configuration have been shown to operate in three regimes: corona , glow, and...assisted combustion Plasma assisted ignition Aircraft propulsionA nanosecond repetitively pulsed (NRP) discharge in the spark regime has been investigated

Objective evaluation of choroidal melanin contents with polarization-sensitive optical coherence tomography

NASA Astrophysics Data System (ADS)

Miura, Masahiro; Makita, Shuichi; Yasuno, Yoshiaki; Ikuno, Yasushi; Uematsu, Sato; Iwasaki, Takuya; Goto, Hiroshi

2018-02-01

We non-invasively evaluated choroidal melanin contents in human eyes with PS-OCT. We calculated the percentage area of low DOPU in the choroidal interstitial stroma for Vogt-Koyanagi- Harada disease with sunset glow fundus, without sunset glow fundus, control group and tessellated fundus with high myopia. The mean percentage area of low DOPU in the sunset group was significantly lower than the other groups. PS-OCT provides an in vivo objective evaluation of choroidal melanin loss in vivo human eyes.

Rapid eradication of bacterial phytopathogens by atmospheric pressure glow discharge generated in contact with a flowing liquid cathode.

PubMed

Motyka, Agata; Dzimitrowicz, Anna; Jamroz, Piotr; Lojkowska, Ewa; Sledz, Wojciech; Pohl, Pawel

2018-06-01

Diseases caused by phytopathogenic bacteria are responsible for significant economic losses, and these bacteria spread through diverse pathways including waterways and industrial wastes. It is therefore of high interest to develop potent methods for their eradication. Here, antibacterial properties of direct current atmospheric pressure glow discharge (dc-APGD) generated in contact with flowing bacterial suspensions were examined against five species of phytopathogens. Complete eradication of Clavibacter michiganensis subsp. sepedonicus, Dickeya solani, and Xanthomonas campestris pv. campestris from suspensions of OD 600  ≈ 0.1 was observed, while there was at least 3.43 logarithmic reduction in population densities of Pectobacterium atrosepticum and Pectobacterium carotovorum subsp. carotovorum. Analysis of plasma-chemical parameters of the dc-APGD system revealed its high rotational temperatures of 2,300 ± 100 K and 4,200 ± 200 K, as measured from N 2 and OH molecular bands, respectively, electron temperature of 6,050 ± 400 K, vibrational temperature of 4000 ± 300 K, and high electron number density of 1.1 × 10 15  cm -1 . In addition, plasma treatment led to formation of numerous reactive species and states in the treated liquid, including reactive nitrogen and oxygen species such as NO x , NH, H 2 O 2 , O 2 , O, and OH. Further examination revealed that bactericidal activity of dc-APGD was primarily due to presence of these reactive species as well as to UVA, UVB, and UVC irradiation generated by the dc-APGD source. Plasma treatment also resulted in an increase in temperature (from 24.2 to 40.2 °C) and pH (from 6.0 to 10.8) of bacterial suspensions, although these changes had minor effects on cell viability. All results suggest that the newly developed dc-APGD-based system can be successfully implemented as a simple, rapid, efficient, and cost-effective disinfection method for liquids originating from different industrial and agricultural settings. © 2018 Wiley Periodicals, Inc.

Negative-ion formation in the explosives RDX, PETN, and TNT using the Reversal Electron Attachment Detection (READ) technique

NASA Technical Reports Server (NTRS)

Chutijian, Ara; Boumsellek, S.; Alajajian, S. H.

1992-01-01

In the search for high sensitivity and direct atmospheric sampling of trace species, techniques have been developed such as atmospheric-sampling, glow-discharge ionization (ASGDI), corona discharge, atmospheric pressure ionization (API), electron-capture detection (ECD), and negative-ion chemical ionization (NICI) that are capable of detecting parts-per-billion to parts-per-trillion concentrations of trace species. These techniques are based on positive- or negative-ion formation via charge-transfer to the target, or electron capture under multiple-collision conditions in a Maxwellian distribution of electron energies at the source temperature. One drawback of the high-pressure, corona- or glow-discharge devices is that they are susceptible to interferences either through indistinguishable product masses, or through undesired ion-molecule reactions. The ASGDI technique is relatively immune from such interferences, since at target concentrations of less than 1 ppm the majority of negative ions arises via electron capture rather than through ion-molecule chemistry. A drawback of the conventional ECD, and possibly of the ASGDI, is that they exhibit vanishingly small densities of electrons with energies in the range 0-10 millielectron volts (meV), as can be seen from a typical Maxwellian electron energy distribution function at T = 300 K. Slowing the electrons to these subthermal (less than 10 meV) energies is crucial, since the cross section for attachment of several large classes of molecules is known to increase to values larger than 10(exp -12) sq cm at near-zero electron energies. In the limit of zero energy these cross sections are predicted to diverge as epsilon(exp -1/2), where epsilon is the electron energy. In order to provide a better 'match' between the electron energy distribution function and attachment cross section, a new concept of attachment in an electrostatic mirror was developed. In this scheme, electrons are brought to a momentary halt by reversing their direction with electrostatic fields. At this turning point the electrons have zero or near-zero energy. A beam of target molecules is introduced, and the resultant negative ions extracted. This basic idea has been recently improved to allow for better reversal geometry, higher electron currents, lower backgrounds, and increased negative-ion extraction efficiency. We present herein application of the so-called reversal electron attachment detector (READ) to the study of negative-ion formation in the explosives molecules RDX, PETN, and TNT under single-collision conditions.

Background oriented schlieren measurement of the refractive index field of air induced by a hot, cylindrical measurement object.

PubMed

Beermann, Rüdiger; Quentin, Lorenz; Pösch, Andreas; Reithmeier, Eduard; Kästner, Markus

2017-05-10

To optically capture the topography of a hot measurement object with high precision, the light deflection by the inhomogeneous refractive index field-induced by the heat transfer from the measurement object to the ambient medium-has to be considered. We used the 2D background oriented schlieren method with illuminated wavelet background, an optical flow algorithm, and Ciddor's equation to quantify the refractive index field located directly above a red-glowing, hot measurement object. A heat transfer simulation has been implemented to verify the magnitude and the shape of the measured refractive index field. Provided that no forced external flow is disturbing the shape of the convective flow originating from the hot object, a laminar flow can be observed directly above the object, resulting in a sharply bounded, inhomogeneous refractive index field.

Activated recombinative desorption: A potential component in mechanisms of spacecraft glow

NASA Technical Reports Server (NTRS)

Cross, J. B.

1985-01-01

The concept of activated recombination of atomic species on surfaces can explain the production of vibrationally and translationally excited desorbed molecular species. Equilibrium statistical mechanics predicts that the molecular quantum state distributions of desorbing molecules is a function of surface temperature only when the adsorption probability is unity and independent of initial collision conditions. In most cases, the adsorption probability is dependent upon initial conditions such as collision energy or internal quantum state distribution of impinging molecules. From detailed balance, such dynamical behavior is reflected in the internal quantum state distribution of the desorbing molecule. This concept, activated recombinative desorption, may offer a common thread in proposed mechanisms of spacecraft glow. Using molecular beam techniques and equipment available at Los Alamos, which includes a high translational energy 0-atom beam source, mass spectrometric detection of desorbed species, chemiluminescence/laser induced fluorescence detection of electronic and vibrationally excited reaction products, and Auger detection of surface adsorbed reaction products, a fundamental study of the gas surface chemistry underlying the glow process is proposed.

Borax as flux on sintering of iron Ancor Steel 1000® under glow discharge

NASA Astrophysics Data System (ADS)

Ariza Suarez, H. G.; Sarmiento Santos, A.; Ortiz Otálora, C. A.

2016-02-01

This work studies the flux effect of borax (di sodium tetraborate decahydrate) on sintering of iron Ancor Steel 1000® in abnormal glow discharge. The incidence of the percentage by weight of borax and the sintering temperature in the process were observed. Samples of powder metallurgical iron were prepared with proportions of 0.50%, 2.0%, 4.0% and 6.0% by weight of borax using the procedures of powder metallurgy. The samples were sintered at 800 and 1100°C for 30min, by glow discharge at low pressure in a reducing atmosphere composed of 20% H2+80% Ar. The samples in compact green-state were analyzed by TGA-DSC to determine the fusion process and mass loss during sintering. The analysis of microhardness and density, shows that at a sintering temperature of 800°C the sample density decreases and the sample microhardness increases with respect to sintered samples without borax. Sintered samples were analysed by DRX showing the absence of precipitates.

Universal sensor based on the spectroscopy of glow discharge for the detection of traces of atoms or molecules in air

NASA Astrophysics Data System (ADS)

Atutov, S. N.; Galeyev, A. E.; Plekhanov, A. I.; Yakovlev, A. V.

2018-03-01

A sensitive and versatile sensor for the detection of traces of atoms or molecules in air based on the emission spectroscopy of glow discharge in air has been developed and studied. The advantages of this sensor compared to other well-known methods are that it renders the use of ultrahigh vacuum or cryogenic temperatures superfluous. The sensor is insensitive to the presence of water vapor (for example, in exhaled air) because of the absence of strong water lines in the visible spectral range. It has a high spectral selectivity limited only by Doppler broadening of the emission lines. The high selectivity of the sensor combined with a wide spectral range allows the detection of many toxic impurities, which can be present in air. Moreover, the spectral range used covers almost all biomarkers in exhaled air, making the proposed sensor extremely interesting for medical applications. To our knowledge, the proposed method is the first based on a glow discharge in air.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kinzey, Bruce R.; Perrin, Tess E.; Miller, Naomi J.

A significant amount of public attention has recently focused on perceived impacts of converting street lighting from incumbent lamp-based products to LED technology. Much of this attention pertains to the higher content of short wavelength light (commonly referred to as "blue light") of LEDs and its attendant influences on sky glow (a brightening of the night sky that can interfere with astronomical observation and may be associated with a host of other issues). The complexity of this topic leads to common misunderstandings and misperceptions among the public, and for this reason the U.S. Department of Energy Solid-State Lighting Program embarkedmore » on a study of sky glow using a well-established astronomical model to investigate some of the primary factors influencing sky glow. This report details the results of the investigation and attempts to present those results in terms accessible to the general lighting community. The report also strives to put the results into a larger context, and help educate interested readers on various topics relevant to the issues being discussed.« less

Prompt isothermal decay properties of the Sr4Al14O25 co-doped with Eu2+ and Dy3+ persistent luminescent phosphor

NASA Astrophysics Data System (ADS)

Asal, Eren Karsu; Polymeris, George S.; Gultekin, Serdar; Kitis, George

2018-06-01

Thermoluminescence (TL) techniques are very useful in the research of the persistent Luminescence (PL) phosphors research. It gives information about the existence of energy levels within the forbidden band, its activation energy, kinetic order, lifetime etc. The TL glow curve of Sr4Al14O25 :Eu2+,Dy3+ persistent phosphor, consists of two well separated glow peaks. The TL techniques used to evaluate activation energy were the initial rise, prompt isothermal decay (PID) of TL of each peak at elevated temperatures and the glow - curve fitting. The behavior of the PID curves of the two peak is very different. According to the results of the PID procedure and the subsequent data analysis it is suggested that the mechanism behind the low temperature peak is a delocalized transition. On the other hand the mechanism behind the high temperature peak is localized transition involving a tunneling recombination between electron trap and luminescence center.

Isothermal decay studies of intermediate energy levels in quartz.

PubMed

Veronese, I; Giussani, A; Göksu, H Y; Martini, M

2004-05-01

The recent interest in the thermoluminescence of quartz extracted from unfired building materials, such as mortar and concrete for dose reconstruction applications, led to the requirement of an accurate determination of the lifetime of the intermediate glow peaks in this mineral. The prediction of the lifetimes of these peaks is helpful in establishing the likely time range within which retrospective measurements can be carried out. These peaks, corresponding to intermediate energy levels, occur in the glow curve in the temperature range 150-250 degrees C (heating rate 2 degrees C/s). Lifetimes of 720+/-70 days and 580+/-70 years (at a temperature of 15 degrees C) were derived for the two main peaks placed in the glow curve at approximately 150 degrees C and 200 degrees C, respectively, using the isothermal decay technique. These results as well as the estimated values of the trap parameters (thermal activation energy and frequency factor) have been compared with the data already available in the literature.

Development of a DC Glow Discharge Exhibit for the Demonstration of Plasma Behavior in a Magnetic Field

NASA Astrophysics Data System (ADS)

Bruder, Daniel

2010-11-01

The DC Glow Discharge Exhibit is intended to demonstrate the effects a magnetic field produces on a plasma in a vacuum chamber. The display, which will be featured as a part of The Liberty Science Center's ``Energy Quest Exhibition,'' consists of a DC glow discharge tube and information panels to educate the general public on plasma and its relation to fusion energy. Wall posters and an information booklet will offer brief descriptions of fusion-based science and technology, and will portray plasma's role in the development of fusion as a viable source of energy. The display features a horse-shoe magnet on a movable track, allowing viewers to witness the effects of a magnetic field upon a plasma. The plasma is created from air within a vacuum averaging between 100-200 mTorr. Signage within the casing describes the hardware components. The display is pending delivery to The Liberty Science Center, and will replace a similar, older exhibit presently at the museum.

Acting green elicits a literal warm glow

NASA Astrophysics Data System (ADS)

Taufik, Danny; Bolderdijk, Jan Willem; Steg, Linda

2015-01-01

Environmental policies are often based on the assumption that people only act environmentally friendly if some extrinsic reward is implicated, usually money. We argue that people might also be motivated by intrinsic rewards: doing the right thing (such as acting environmentally friendly) elicits psychological rewards in the form of positive feelings, a phenomenon known as warm glow. Given the fact that people's psychological state may affect their thermal state, we expected that this warm glow could express itself quite literally: people who act environmentally friendly may perceive the temperature to be higher. In two studies, we found that people who learned they acted environmentally friendly perceived a higher temperature than people who learned they acted environmentally unfriendly. The underlying psychological mechanism pertains to the self-concept: learning you acted environmentally friendly signals to yourself that you are a good person. Together, our studies show that acting environmentally friendly can be psychologically rewarding, suggesting that appealing to intrinsic rewards can be an alternative way to encourage pro-environmental actions.

Continuous wavelet transform based time-scale and multifractal analysis of the nonlinear oscillations in a hollow cathode glow discharge plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nurujjaman, Md.; Narayanan, Ramesh; Iyengar, A. N. Sekar

2009-10-15

Continuous wavelet transform (CWT) based time-scale and multifractal analyses have been carried out on the anode glow related nonlinear floating potential fluctuations in a hollow cathode glow discharge plasma. CWT has been used to obtain the contour and ridge plots. Scale shift (or inversely frequency shift), which is a typical nonlinear behavior, has been detected from the undulating contours. From the ridge plots, we have identified the presence of nonlinearity and degree of chaoticity. Using the wavelet transform modulus maxima technique we have obtained the multifractal spectrum for the fluctuations at different discharge voltages and the spectrum was observed tomore » become a monofractal for periodic signals. These multifractal spectra were also used to estimate different quantities such as the correlation and fractal dimension, degree of multifractality, and complexity parameters. These estimations have been found to be consistent with the nonlinear time series analysis.« less

Electric discharge during electrosurgery

PubMed Central

Shashurin, Alexey; Scott, David; Zhuang, Taisen; Canady, Jerome; Beilis, Isak I.; Keidar, Michael

2015-01-01

Electric discharge utilized for electrosurgery is studied by means of a recently developed method for the diagnostics of small-size atmospheric plasma objects based on Rayleigh scattering of microwaves on the plasma volume. Evolution of the plasma parameters in the near-electrode sheaths and in the positive column is measured and analyzed. It is found that the electrosurgical system produces a glow discharge of alternating current with strongly contracted positive column with current densities reaching 103 A/cm2. The plasma electron density and electrical conductivities in the channel were found be 1016 cm−3 and (1-2) Ohm−1cm−1, respectively. The discharge interrupts every instance when the discharge-driving AC voltage crosses zero and re-ignites again every next half-wave at the moment when the instant voltage exceeds the breakdown threshold. PMID:25880721

Electric discharge during electrosurgery.

PubMed

Shashurin, Alexey; Scott, David; Zhuang, Taisen; Canady, Jerome; Beilis, Isak I; Keidar, Michael

2015-04-16

Electric discharge utilized for electrosurgery is studied by means of a recently developed method for the diagnostics of small-size atmospheric plasma objects based on Rayleigh scattering of microwaves on the plasma volume. Evolution of the plasma parameters in the near-electrode sheaths and in the positive column is measured and analyzed. It is found that the electrosurgical system produces a glow discharge of alternating current with strongly contracted positive column with current densities reaching 10(3) A/cm(2). The plasma electron density and electrical conductivities in the channel were found be 10(16) cm(-3) and (1-2) Ohm(-1) cm(-1), respectively. The discharge interrupts every instance when the discharge-driving AC voltage crosses zero and re-ignites again every next half-wave at the moment when the instant voltage exceeds the breakdown threshold.

Thermoluminesence of gamma rays irradiated CaSO4 nanorods doped with different elements

NASA Astrophysics Data System (ADS)

Salah, Numan

2015-01-01

Nanorods of calcium sulfate (CaSO4) activated by Ag, Cu, Dy, Eu and Tb were synthesized by the co-precipitation technique. They were irradiated by γ-rays in a wide range of exposures and studied for their thermoluminesence (TL) properties. The as-synthesized samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and photoluminescence (PL) emission spectra. SEM images show that the samples doped with rare earths elements (i.e. Dy, Eu and Tb) have thinner nanorods than the other samples, while XRD pattern shows a complete crystalline structures in a monoclinic phase. The TL glow curves of these samples show two components. The first one include low temperature glow peaks at around 125 °C, while the second component shows high temperature peaks in the range 230-270 °C. These glow peaks diver from sample to sample by their TL intensity. The TL results are promising, particularly that of Tb and Eu. Tb doped sample is found to be a highly TL sensitive with a prominent glow peak at around 270 °C, while Eu has created very active, high dense electron traps. The later shows quite linear response in the whole studied exposures i.e. 10 Gy-10 kGy. These results show that Eu or Tb doped CaSO4 nanorods might be proper candidates as dosimeters for high doses of ionizing radiations used in irradiation of foods and seeds.

Cu+ emission in Li2BPO5 material for thermoluminescence dosimetry

NASA Astrophysics Data System (ADS)

Puppalwar, S. P.; Dhoble, S. J.; Kumar, Animesh

2012-05-01

In this study, Li2BPO5 doped with Cu and that co-doped with Mg are synthesized by the wet chemical technique and exposed to γ rays of 60Co to determine their thermoluminescence (TL) properties. The X-ray diffraction technique shows the crystalline nature of the prepared material. The photoluminescence (PL) emission spectra of Li2BPO5:Cu phosphor show the strong prominent peak at 368 nm in the violet region of the visible spectrum due to the transition of 3d94s1 ↔ 3d10 of monovalent copper ion. The PL emission of Li2BPO5:Cu is enhanced by the addition of Mg. The TL glow curves of γ-irradiated Li2BPO5:Cu sample show one glow peak at 143°C, indicating that only one set of traps is being activated within the particular temperature range each with its own value of activation energy (E) and frequency factor (s). The trapping parameters associated with the prominent glow peak of Li2BPO5:Cu are calculated using the glow curve shape (Chen's) method. The release of hole/electron from defect centers at the characteristic trap site initiates the luminescence process in these materials. A linear TL response is observed in Li2BPO5:Cu in a long span of exposures. The sensitivity of Li2BPO5:Cu sample is observed to be 7.8 times that of (TLD-100) LiF:Mg, Ti.

Diffuse gamma-ray emission from pulsars in the Large Magellanic Cloud

NASA Technical Reports Server (NTRS)

Hartmann, Dieter H.; Brown, Lawrence E.; Schnepf, Neil

1993-01-01

We investigate the contribution of pulsars to the diffuse gamma-ray emission from the LMC. The pulsar birth rate in the LMC is a factor of about 10 lower than that of the Galaxy and the distance to pulsars in the LMC is about 5-10 times larger than to Galactic pulsars. The resulting total integrated photon flux from LMC pulsars is thus reduced by a factor of about 100 to 1000. However, the surface brightness is not reduced by the same amount because of the much smaller angular extent of the LMC in comparison to the diffuse glow from the Galactic plane. We show that gamma-ray emission due to pulsars born in the LMC could produce gamma-ray fluxes that are larger than the inverse Compton component from relativistic cosmic-ray electrons and a significant fraction of the extragalactic isotropic background or the diffuse Galactic background in that direction. The diffuse pulsar glow above 100 MeV should therefore be included in models of high-energy emission from the LMC. For a gamma-ray beaming fraction of order unity the detected emissions from the LMC constrain the pulsar birth rate to less than one per 50 yr. This limit is about one order of magnitude above the supernova rate inferred from the historic record or from the star-formation rate.

Pollution-free road lighting

NASA Astrophysics Data System (ADS)

Schreuder, Duco A.

They relate to reducing road accidents and some forms of crime but also enhance the social safety of residents and pedestrians and the amenity for residents. Road traffic in developing countries is much more hazardous than in industrialized countries. Accident rates in 'low' income countries may be as much as 35 times higher than in 'high' income countries. Thus, it might be much more cost-effective to light roads in the developing world than in the industrialized world. Fighting light pollution is more pressing in developing countries as most of the major high-class astronomical observatories are there. Astronomical observations are disturbed by light from outdoor lighting installations, part of which is scattered in the atmosphere to form 'sky glow'. The International Lighting Commission CIE has published a Technical Report giving general guidance for lighting designers and policy makers on the reduction of the sky glow. Lighting improves visibility, essential for almost all human activity. However, light that hits the road contributes to visibility only if it is reflected. In poorly designed lighting equipment much of the lumen output of the lamps is sent directly upwards. This can be avoided by properly defined light fittings. The light output of fittings is determined by their optical quality and by the installation maintenance factor. Open fittings are to be preferred. If mounted horizontally, they make street lighting with the least light pollution.

Characterization of Doped Amorphous Silicon Thin Films through the Investigation of Dopant Elements by Glow Discharge Spectrometry. A Correlation of Conductivity and Bandgap Energy Measurements

PubMed Central

Sánchez, Pascal; Lorenzo, Olaya; Menéndez, Armando; Menéndez, Jose Luis; Gomez, David; Pereiro, Rosario; Fernández, Beatriz

2011-01-01

The determination of optical parameters, such as absorption and extinction coefficients, refractive index and the bandgap energy, is crucial to understand the behavior and final efficiency of thin film solar cells based on hydrogenated amorphous silicon (a-Si:H). The influence of small variations of the gas flow rates used for the preparation of the p-a-SiC:H layer on the bandgap energy, as well as on the dopant elements concentration, thickness and conductivity of the p-layer, is investigated in this work using several complementary techniques. UV-NIR spectrophotometry and ellipsometry were used for the determination of bandgap energies of four p-a-SiC:H thin films, prepared by using different B2H6 and SiH4 fluxes (B2H6 from 12 sccm to 20 sccm and SiH4 from 6 sccm to 10 sccm). Moreover, radiofrequency glow discharge optical emission spectrometry technique was used for depth profiling characterization of p-a-SiC:H thin films and valuable information about dopant elements concentration and distribution throughout the coating was found. Finally, a direct relationship between the conductivity of p-a-SiC:H thin films and the dopant elements concentration, particularly boron and carbon, was observed for the four selected samples. PMID:21731436

Infrared monitoring of the Space Station environment

NASA Technical Reports Server (NTRS)

Kostiuk, Theodor; Jennings, Donald E.; Mumma, Michael J.

1988-01-01

The measurement and monitoring of infrared emission in the environment of the Space Station has a twofold importance - for the study of the phenomena itself and as an aid in planning and interpreting Station based infrared experiments. Spectral measurements of the infrared component of the spacecraft glow will, along with measurements in other spectral regions, provide data necessary to fully understand and model the physical and chemical processes producing these emissions. The monitoring of the intensity of these emissions will provide background limits for Space Station based infrared experiments and permit the determination of optimum instrument placement and pointing direction. Continuous monitoring of temporal changes in the background radiation (glow) will also permit better interpretation of Station-based infrared earth sensing and astronomical observations. The primary processes producing infrared emissions in the Space Station environment are: (1) Gas phase excitations of Station generated molecules ( e.g., CO2, H2O, organics...) by collisions with the ambient flux of mainly O and N2. Molecular excitations and generation of new species by collisions of ambient molecules with Station surfaces. They provide a list of resulting species, transition energies, excitation cross sections and relevant time constants. The modeled spectrum of the excited species occurs primarily at wavelengths shorter than 8 micrometer. Emissions at longer wavelengths may become important during rocket firing or in the presence of dust.

The mechanism of nickel ferrite formation by glow discharge effect

NASA Astrophysics Data System (ADS)

Frolova, L. A.

2018-04-01

The influence of various factors on the formation of nickel ferrite by the glow discharge effect has been studied. The ferritization process in the system FeSO4-NiSO4-NaOH-H2O has been studied by the methods of potentiometric titration, measurement of electrical conductivity, residual concentrations and apparent sediment volume. It has been established that the process proceeds in a multistage fashion at pH 11-12 with the formation of polyhydroxo complexes, an intermediate compound and the ferrite formation by its oxidation with active radicals.

Space Science

NASA Image and Video Library

2003-03-03

Researchers in Robert Ferl’s lab at the University of Florida in Gainesville, genetically altered this Arabdopsis Thaliana (a brassica species) plant to learn how extreme environments, such as the low atmospheric pressure on Mars, affect plant genes. They inserted green fluorescent protein (GFP) near the on/off switches for anoxia and drought genes. When those genes were turned on after exposure to reduced atmospheric pressure, GFP was turned on as well, causing cells expressing those genes to glow green under a blue light. The natural fluorescence of chlorophyll accounts for the red glow.

Child-Langmuir law applicability for a cathode sheath description of glow discharge in hydrogen

NASA Astrophysics Data System (ADS)

Lisovskiy, V. A.; Artushenko, K. P.; Yegorenkov, V. D.

2016-08-01

The present paper reveals that the Child-Langmuir law version with the constant ion mobility has to be applied for the cathode sheath description of the glow discharge in hydrogen. Using the analytical model we demonstrate that even in a high electric field the constant mobility law version rather than that for the constant ion mean free path has to hold in the case of impeded charge exchange and the dominant effect of polarization forces on the ion motion through the cathode sheath.

Self-Assembly of Large-Scale Shape-Controlled DNA Nano-Structures

DTIC Science & Technology

2014-12-16

discharged carbon-coated TEM grids for 4 min and then stained for 1 min using a 2% aqueous uranyl formate solution containing 25 mM NaOH. Imaging was...temperature for 3 h in the dark. TEM imaging. For imaging, 2,5 pi annealed sample was adsorbed for 2 min onto glow- discharged , carbon-coated TEM grids...Imaging. For ’I’EM imaging, a 3.S //L sample (l—5 nM) was adsorbed onto glow discharged carbon-coated TEM grids for 4 min and then stained for 1 min or a

Genetically Altered Plant Species

NASA Technical Reports Server (NTRS)

2003-01-01

Researchers in Robert Ferl's lab at the University of Florida in Gainesville, genetically altered this Arabdopsis Thaliana (a brassica species) plant to learn how extreme environments, such as the low atmospheric pressure on Mars, affect plant genes. They inserted green fluorescent protein (GFP) near the on/off switches for anoxia and drought genes. When those genes were turned on after exposure to reduced atmospheric pressure, GFP was turned on as well, causing cells expressing those genes to glow green under a blue light. The natural fluorescence of chlorophyll accounts for the red glow.

Uncertainty of relative sensitivity factors in glow discharge mass spectrometry

NASA Astrophysics Data System (ADS)

Meija, Juris; Methven, Brad; Sturgeon, Ralph E.

2017-10-01

The concept of the relative sensitivity factors required for the correction of the measured ion beam ratios in pin-cell glow discharge mass spectrometry is examined in detail. We propose a data-driven model for predicting the relative response factors, which relies on a non-linear least squares adjustment and analyte/matrix interchangeability phenomena. The model provides a self-consistent set of response factors for any analyte/matrix combination of any element that appears as either an analyte or matrix in at least one known response factor.

Investigation of Sheath Phenomena in Electronegative Glow Discharges.

DTIC Science & Technology

1985-04-01

NUMBER 22c OFFICE SYMBOL DD FORM 1473, 83 APR )sTI,)N OF I IAN 71lIS rfJBSOLE ’I. UNCLASSIFIED _______ SECURITY CLASSIFICATION OF THIS PAGE _t,[L L; Z...Energy Electron Cross Sections in HCI 199 . .. . ° ° . - LiST OF TABLES TABLE PAGE 1 Summary uf GLOW Code Fesults for He/HCl rNixtures... Cross Src: tiuns in HCI. ......... ... 197 A, i~lX I 4.’ S[LIION I. INTRODUCTION 1. INTRODUCT1O0 AND DEFIr’ITION OF TEI<.S An understanding of the role

Annual Gaseous Electronics Conference (41st) Held in Minneapolis, Minnesota on 18-21 October 1988

DTIC Science & Technology

1989-09-01

IMPEDANCE J. W. Butterbaugh, L. D. Baston and H. H. Sawin E-34. TEMPORAL AND SPATIAL PLASMA POTENTIAL MEASUREMENT IN PARALLEL PLATE RF GLOW DISCHARGE C...DISCHARGES P. J. Hargis, Jr. and K. E. Grecr.’ 10:51 - 11:04 LA-4. CHARACTERIZATION OF CF4 PLASMA KINETICS BY MODULATED POWER RELAXATION L. D. Baston and H. H...No. ECS-8704529 5n, E-33 Measurement and Analysis of RF Glow Discharge Electrical Impedance, J.W. BUTTERBAUGH, L.D. BASTON , and H.H. SAWIN

Atomic hydrogen as a launch vehicle propellant

NASA Technical Reports Server (NTRS)

Palaszewski, Bryan A.

1990-01-01

An analysis of several atomic hydrogen launch vehicles was conducted. A discussion of the facilities and the technologies that would be needed for these vehicles is also presented. The Gross Liftoff Weights (GLOW) for two systems were estimated; their specific impulses (I sub sp) were 750 and 1500 lb (sub f)/s/lb(sub m). The atomic hydrogen launch vehicles were also compared to the currently planned Advanced Launch System design concepts. Very significant GLOW reductions of 52 to 58 percent are possible over the Advanced Launch System designs. Applying atomic hydrogen propellants to upper stages was also considered. Very high I(sub sp) (greater than 750 1b(sub f)/s/lb(sub m) is needed to enable a mass savings over advanced oxygen/hydrogen propulsion. Associated with the potential benefits of high I(sub sp) atomic hydrogen are several challenging problems. Very high magnetic fields are required to maintain the atomic hydrogen in a solid kilogauss (3 Tesla). Also the storage temperature of the propellant is 4 K. This very low temperature will require a large refrigeration facility for the launch vehicle. The design considerations for a very high recombination rate for the propellant are also discussed. A recombination rate of 210 cm/s is predicted for atomic hydrogen. This high recombination rate can produce very high acceleration for the launch vehicle. Unique insulation or segmentation to inhibit the propellant may be needed to reduce its recombination rate.

Insights from the Global Longitudinal Study of Osteoporosis in Women (GLOW).

PubMed

Watts, Nelson B

2014-07-01

GLOW is an observational, longitudinal, practice-based cohort study of osteoporosis in 60,393 women aged ≥55 years in 10 countries on three continents. In this Review, we present insights from the first 3 years of the study. Despite cost analyses being frequently based on spine and hip fractures, we found that nonvertebral, nonhip fractures were around five times more common and doubled the use of health-care resources compared with hip and spine fractures combined. Fractures not at the four so-called major sites in FRAX(®) (upper arm, forearm, hip and clinical vertebral fractures) account for >40% of all fractures. The risk of fracture is increased by various comorbidities, such as Parkinson disease, multiple sclerosis and lung and heart disease. Obesity, although thought to be protective against all fractures, substantially increased the risk of fractures in the ankle or lower leg. Simple assessment by age plus fracture history has good predictive value for all fractures, but risk profiles differ for first and subsequent fractures. Fractures diminish quality of life as much or more than diabetes mellitus, arthritis and lung disease, yet women substantially underestimate their own fracture risk. Treatment rates in patients at high risk of fracture are below those recommended but might be too frequent in women at low risk. Comorbidities and the limits of current therapeutic regimens jeopardize the efficacy of drugs; new regimens should be explored for severe cases.

“Glowing Head” Mice: A Genetic Tool Enabling Reliable Preclinical Image-Based Evaluation of Cancers in Immunocompetent Allografts

PubMed Central

Day, Chi-Ping; Carter, John; Ohler, Zoe Weaver; Bonomi, Carrie; El Meskini, Rajaa; Martin, Philip; Graff-Cherry, Cari; Feigenbaum, Lionel; Tüting, Thomas; Van Dyke, Terry; Hollingshead, Melinda; Merlino, Glenn

2014-01-01

Preclinical therapeutic assessment currently relies on the growth response of established human cell lines xenografted into immunocompromised mice, a strategy that is generally not predictive of clinical outcomes. Immunocompetent genetically engineered mouse (GEM)-derived tumor allograft models offer highly tractable preclinical alternatives and facilitate analysis of clinically promising immunomodulatory agents. Imageable reporters are essential for accurately tracking tumor growth and response, particularly for metastases. Unfortunately, reporters such as luciferase and GFP are foreign antigens in immunocompetent mice, potentially hindering tumor growth and confounding therapeutic responses. Here we assessed the value of reporter-tolerized GEMs as allograft recipients by targeting minimal expression of a luciferase-GFP fusion reporter to the anterior pituitary gland (dubbed the “Glowing Head” or GH mouse). The luciferase-GFP reporter expressed in tumor cells induced adverse immune responses in wildtype mouse, but not in GH mouse, as transplantation hosts. The antigenicity of optical reporters resulted in a decrease in both the growth and metastatic potential of the labeled tumor in wildtype mice as compared to the GH mice. Moreover, reporter expression can also alter the tumor response to chemotherapy or targeted therapy in a context-dependent manner. Thus the GH mice and experimental approaches vetted herein provide concept validation and a strategy for effective, reproducible preclinical evaluation of growth and response kinetics for traceable tumors. PMID:25369133

Pulse-Modulated Radio-Frequency Alternating-Current-Driven Atmospheric-Pressure Glow Discharge for Continuous-Flow Synthesis of Silver Nanoparticles and Evaluation of Their Cytotoxicity toward Human Melanoma Cells.

PubMed

Dzimitrowicz, Anna; Bielawska-Pohl, Aleksandra; diCenzo, George C; Jamroz, Piotr; Macioszczyk, Jan; Klimczak, Aleksandra; Pohl, Pawel

2018-06-02

An innovative and environmentally friendly method for the synthesis of size-controlled silver nanoparticles (AgNPs) is presented. Pectin-stabilized AgNPs were synthesized in a plasma-reaction system in which pulse-modulated radio-frequency atmospheric-pressure glow discharge (pm-rf-APGD) was operated in contact with a flowing liquid electrode. The use of pm-rf-APGD allows for better control of the size of AgNPs and their stability and monodispersity. AgNPs synthesized under defined operating conditions exhibited average sizes of 41.62 ± 12.08 nm and 10.38 ± 4.56 nm, as determined by dynamic light scattering and transmission electron microscopy (TEM), respectively. Energy-dispersive X-ray spectroscopy (EDS) confirmed that the nanoparticles were composed of metallic Ag. Furthermore, the ξ-potential of the AgNPs was shown to be -43.11 ± 0.96 mV, which will facilitate their application in biological systems. Between 70% and 90% of the cancerous cells of the human melanoma Hs 294T cell line underwent necrosis following treatment with the synthesized AgNPs. Furthermore, optical emission spectrometry (OES) identified reactive species, such as NO, NH, N₂, O, and H, as pm-rf-APGD produced compounds that may be involved in the reduction of the Ag(I) ions.

Immunogenicity of a recombinant infectious hematopoietic necrosis virus glycoprotein produced in insect cells.

PubMed

Cain, K D; LaPatra, S E; Shewmaker, B; Jones, J; Byrne, K M; Ristow, S S

1999-04-15

A recombinant infectious hematopoietic necrosis virus (IHNV) glycoprotein (G protein), produced in Spodoptera frugiperda (Sf9) cells following infection with a baculovirus vector containing the full-length (1.6 kb) glycoprotein gene, provided very limited protection in rainbow trout Oncorhynchus mykiss challenged with IHNV. Fish were injected intraperitoneally (i.p.) with Sf9 cells grown at 20 degrees C (RecGlow) or 27 degrees C (RecGhigh) expressing the glycoprotein gene. Various antigen (Ag) preparations were administered to adult rainbow trout or rainbow trout fry. Sera collected from adult fish were evaluated for IHNV neutralization activity by a complement-dependent neutralization assay. Anti-IHNV neutralizing activity was observed in sera, but the percent of fish responding was significantly lower (p < 0.05) in comparison to fish immunized with a low virulence strain of IHNV (LV-IHNV). A small number of fish immunized with RecGlow or RecGhigh possessed IHNV G protein specific antibodies (Abs) in their serum. Cumulative mortality (CM) of rainbow trout fry (mean weight, 1 g) vaccinated by i.p. injection of freeze/thawed Sf9 cells producing RecGlow was 18% in initial trials following IHNV challenge. This level of protection was significant (p < 0.05) but was not long lasting, and neutralizing Abs were not detected in pooled serum samples. When trout fry (mean weight, 0.6 g) were vaccinated with supernatant collected from sonicated Sf9 cells, Sf9 cells producing RecGlow, or Sf9 cells producing RecGhigh, CM averaged 46%. Protection was enhanced over negative controls, but not the positive controls (2% CM), suggesting that in the first trial soluble cellular proteins may have provided some level of non-specific protection, regardless of recombinant protein expression. Although some immunity was elicited in fish, and RecGlow provided short-term protection from IHNV, Ab-mediated protection could not be demonstrated. The results suggest that recombinant G proteins produced in insect cells lack the immunogenicity associated with vaccination of fish with an attenuated strain of IHNV.

Enhancement of SPES source performances.

PubMed

Fagotti, E; Palmieri, A; Ren, X

2008-02-01

Installation of SPES source at LNL was finished in July 2006 and the first beam was extracted in September 2006. Commissioning results confirmed very good performance of the extracted current density. Conversely, source reliability was very poor due to glow-discharge phenomena, which were caused by the ion source axial magnetic field protruding in the high-voltage column. This problem was fixed by changing the stainless steel plasma electrode support with a ferromagnetic one. This new configuration required us to recalculate ion source solenoids positions and fields in order to recover the correct resonance pattern. Details on magnetic simulations and experimental results of high voltage column shielding are presented.

Effects of microbial loading and sporulation temperature on atmospheric plasma inactivation of Bacillus subtilis spores

NASA Astrophysics Data System (ADS)

Deng, X. T.; Shi, J. J.; Shama, G.; Kong, M. G.

2005-10-01

Current inactivation studies of Bacillus subtilis spores using atmospheric-pressure glow discharges (APGD) do not consider two important factors, namely microbial loading at the surface of a substrate and sporulation temperature. Yet these are known to affect significantly microbial resistance to heat and hydrogen peroxide. This letter investigates effects of microbial loading and sporulation temperature on spore resistance to APGD. It is shown that microbial loading can lead to a stacking structure as a protective shield against APGD treatment and that high sporulation temperature increases spore resistance by altering core water content and cross-linked muramic acid content of B. subtilis spores.

Assessment of Corona/Arcing Hazard for Electron Beam Welding in Space Shuttle Bay at LEO for ISWE: Test Results

NASA Technical Reports Server (NTRS)

Nunes, A. C., Jr.; Russell, C.; Vaughn, J.; Stocks, C.; ODell, D.; Bhat, B.

1996-01-01

Test welds were made in argon over a range of pressures from 10-5 to 10-3 torr (the latter pressure an order of magnitude above pressures anticipated in the space shuttle bay during welding) with and without plasma on 304 stainless steel, 6Al-4V titanium, and 5456 aluminum in search of any possible unwanted electrical discharges. Only a faint steady glow of beam-excited atoms around the electron beam and sometimes extending out into the vacuum chamber was observed. No signs of current spiking or of any potentially dangerous electrical discharge were found.

Ultraviolet corona detection sensor study

NASA Technical Reports Server (NTRS)

Schmitt, R. J.; MATHERN

1976-01-01

The feasibility of detecting electrical corona discharge phenomena in a space simulation chamber via emission of ultraviolet light was evaluated. A corona simulator, with a hemispherically capped point to plane electrode geometry, was used to generate corona glows over a wide range of pressure, voltage, current, electrode gap length and electrode point radius. Several ultraviolet detectors, including a copper cathode gas discharge tube and a UV enhanced silicon photodiode detector, were evaluated in the course of the spectral intensity measurements. The performance of both silicon target vidicons and silicon intensified target vidicons was evaluated analytically using the data generated by the spectroradiometer scans and the performance data supplied by the manufacturers.

The other prey-capture silk: Fibres made by glow-worms (Diptera: Keroplatidae) comprise cross-β-sheet crystallites in an abundant amorphous fraction.

PubMed

Walker, Andrew A; Weisman, Sarah; Trueman, Holly E; Merritt, David J; Sutherland, Tara D

2015-09-01

Glow-worms (larvae of dipteran genus Arachnocampa) are restricted to moist habitats where they capture flying prey using snares composed of highly extensible silk fibres and sticky mucus droplets. Little is known about the composition or structure of glow-worm snares, or the extent of possible convergence between glow-worm and arachnid capture silks. We characterised Arachnocampa richardsae silk and mucus using X-ray scattering, Fourier transform infrared spectroscopy and amino acid analysis. Silk but not mucus contained crystallites of the cross-β-sheet type, which occur in unrelated insect silks but have not been reported previously in fibres used for prey capture. Mucus proteins were rich in Gly (28.5%) and existed in predominantly a random coil structure, typical of many adhesive proteins. In contrast, the silk fibres were unusually rich in charged and polar residues, particularly Lys (18.1%), which we propose is related to their use in a highly hydrated state. Comparison of X-ray scattering, infrared spectroscopy and amino acid analysis data suggests that silk fibres contain a high fraction of disordered protein. We suggest that in the native hydrated state, silk fibres are capable of extension via deformation of both disordered regions and cross-β-sheet crystallites, and that high extensibility is an adaptation promoting successful prey capture. This study illustrates the rich variety of protein motifs that are available for recruitment into biopolymers, and how convergently evolved materials can nevertheless be based on fundamentally different protein structures. Crown Copyright © 2015. Published by Elsevier Inc. All rights reserved.

Fine Motor Differences and Prenatal Serotonin Reuptake Inhibitors Exposure.

PubMed

Partridge, Marie-Claire A E; Salisbury, Amy L; LaGasse, Linda L

2016-08-01

To examine fine motor differences between preschoolers with prenatal exposure to serotonin reuptake inhibitor (SRI) and children of mothers with major depressive disorder. A subset of children (N = 40) from a larger study on the effects of prenatal SRI and untreated major depressive disorder participated in a kinematic task of visual motor and fine motor functions at ages 4-5 years: exposure to SRI (n = 15), untreated major depressive disorder exposure (n = 10), and the control group (n = 15). The task was to reach and secure a peg, then drop it in a small hole near the start position in the light condition with full visibility or in the glow condition in which a phosphorescent peg glows in the dark. Movement-tracking software measured the positioning of the moving hand and fingers. In the glow condition, the group exposed to SRIs had a greater proportion of maximum aperture than the group with major depressive disorder, and the group exposed to SRIs was slower than the group with major depressive disorder to drop the peg into the hole. In the glow condition, the trajectory of the group exposed to SRI was less straight than the group with major depressive disorder, and the group with major depressive disorder had a straighter trajectory than the control group. This study provides evidence that preschool aged children with prenatal SRI exposure have poorer fine motor and visual-motor control compared with those with prenatal untreated major depressive disorder. Copyright © 2016 Elsevier Inc. All rights reserved.

Thermally stimulated luminescence studies of undoped, Cu- and Mn-doped CaSO4 compounds

NASA Astrophysics Data System (ADS)

Manam, J.; Das, S.

Thermally stimulated luminescence (TSL) of undoped and doped CaSO4 with activators such as Cu and Mn has been investigated. The polycrystalline samples of undoped and doped CaSO4 are prepared by the melting method. The formation of CaSO4 compound is confirmed by X-ray diffraction and Fourier transform infrared studies. Scanning electron microscopic studies of CaSO4 are also carried out. The TSL glow curves of undoped CaSO4, Cu- and Mn-doped CaSO4 are studied. Comparison of the thermoluminescence (TL) intensity of the most intensive glow peak of Cu-doped CaSO4 compound with that of undoped CaSO4 shows that addition of Cu impurity in CaSO4 compound enhances the TL intensity by about four times. However, the addition of Mn impurity to undoped CaSO4 increases the TL intensity by about three times when compared with that of undoped CaSO4. The TL-dose dependence of all three samples was studied and was observed to be almost linear in the studied range of irradiation time. Among the samples studied, namely undoped CaSO4 and Cu- and Mn-doped CaSO4, Cu-doped CaSO4 is found to be the most sensitive. The trap parameters, namely order of kinetics (b), activation energy (E) and frequency factor (s) associated with the most intensive glow peaks of CaSO4:Mn, CaSO4:Cu and CaSO4 phosphors were determined using the glow curve shape (Chen's) method.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Korolev, Yu. D.; Landl, N. V., E-mail: landl@lnp.hcei.tsc.ru; Geyman, V. G.

Results from studies of a low-current glow discharge with a hollow cathode are presented. A specific feature of the discharge conditions was that a highly emissive tablet containing cesium carbonate was placed in the cathode cavity. In the absence of a tablet, the discharge ignition voltage was typically ≥3.5 kV, while the burning voltage was in the range of 500–600 V. The use of the tablet made it possible to decrease the ignition voltage to 280 V and maintain the discharge burning voltage at a level of about 130 V. A model of the current sustainment in a hollow-cathode dischargemore » is proposed. Instead of the conventional secondary emission yield, the model uses a generalized emission yield that takes into account not only ion bombardment of the cathode, but also the emission current from an external source. The model is used to interpret the observed current−voltage characteristics. The results of calculations agree well with the experimental data. It is shown that, in some discharge modes, the external emission current from the cathode can reach 25% of the total discharge current.« less

BLOWING COSMIC BUBBLES

NASA Technical Reports Server (NTRS)

2002-01-01

This NASA Hubble Space Telescope image reveals an expanding shell of glowing gas surrounding a hot, massive star in our Milky Way Galaxy. This shell is being shaped by strong stellar winds of material and radiation produced by the bright star at the left, which is 10 to 20 times more massive than our Sun. These fierce winds are sculpting the surrounding material - composed of gas and dust - into the curve-shaped bubble. Astronomers have dubbed it the Bubble Nebula (NGC 7635). The nebula is 10 light-years across, more than twice the distance from Earth to the nearest star. Only part of the bubble is visible in this image. The glowing gas in the lower right-hand corner is a dense region of material that is getting blasted by radiation from the Bubble Nebula's massive star. The radiation is eating into the gas, creating finger-like features. This interaction also heats up the gas, causing it to glow. Scientists study the Bubble Nebula to understand how hot stars interact with the surrounding material. Credit: Hubble Heritage Team (AURA/STScI/NASA)

Glow discharge based device for solving mazes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dubinov, Alexander E., E-mail: dubinov-ae@yandex.ru; Mironenko, Maxim S.; Selemir, Victor D.

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 themore » 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.« less

First results on plasma-surface interactions in the tokamak de varennes

NASA Astrophysics Data System (ADS)

Terreault, B.; Boucher, C.; Paynter, R. W.; Ross, G. G.; ThÉriault, D.; Abel, G.; Boivin, R.; Bolton, R. A.; Castracane, J.; Chevalier, G.; Couture, P.; Décoste, R.; Demers, Y.; Dimoff, K.; Glaude, V.; Gregory, B. C.; Haddad, E.; Janicki, C.; Kalnavarns, J.; Lachambre, J. L.; Mai, H. H.; Neufeld, C. R.; Pacher, H. D.; Pacher, G. W.; Richard, N.; Saint-Jacques, R. G.; Saint-Onge, M.; Simm, C.; Stansfield, B. L.; Veilleux, G.; Whyte, D.; Zuzak, W.

1989-04-01

Results of plasma-surface interaction studies made during the early phases of operation of the Tokamak de Varennes are summarized. It was found that the desorption of molecules from the internal walls by UV radiation can be used to reduce the base pressure. Auger depth profiling of stainless steel (SS) samples exposed to hydrogen discharge cleaning has been performed. Glow discharges at about 0.1 mbar etch the surface carbon and oxide at a rate of 0.5 nm/h. RF-glow discharges at 10 -3 mbar result in a rapid reduction of the oxide and its replacement by a carbide layer (the graphite limiters being the source of the carbon). Long-term wall samples of SS and Si have been profiled by Auger and nuclear analysis. The SS sample has a similar composition to that exposed to the RF-glow conditioning. The Si sample is covered by a 3 nm deposit of metals, C and O, and contains 10 16 H/cm 2 within 30 nm of the surface; this dose and width are consistent with the history of the sample.

Membranes produced by plasma enhanced chemical vapor deposition technique for low temperature fuel cell applications

NASA Astrophysics Data System (ADS)

Ennajdaoui, Aboubakr; Roualdes, Stéphanie; Brault, Pascal; Durand, Jean

A plasma polymerization process using a continuous glow discharge has been implemented for preparing proton conducting membranes from trifluoromethane sulfonic acid and styrene. The chemical and physical structure of plasma membranes has been investigated using FTIR and SEM. The films are homogeneous with a good adhesion on commercial gas diffusion layer (E-Tek ®). Their deposition rate can be increased with increasing flow rate and input power. The thermogravimetric analysis under air of plasma polymers has showed a thermal stability up to 140 °C. Compared to the pulsed glow discharge studied in a previous paper, the continuous glow discharge has enabled to enhance the proton conductivity of membranes by a factor 3 (up to 1.7 mS cm -1). Moreover, the low methanol permeability (methanol diffusion coefficient down to 5 × 10 -13 m 2 s -1) of membranes has been confirmed by this study. In an industrial context, a reactor prototype has been developed to manufacture by plasma processes all active layers of fuel cell cores to be integrated in original compact PEMFC or DMFC.

"Let There Be Night" Advocates Dark Skies

NASA Astrophysics Data System (ADS)

Bueter, Chuck

2008-05-01

Let There Be Night is an interactive planetarium program that supports a community-wide experiment to quantify local sky glow. In the planetarium, visitors will experience three aspects of light pollution--glare, sky glow, and light trespass--and decide whether and how to confront dark sky issues. Planetarians can select optional recorded stories and lessons to complement live demonstrations or star talks. As a companion experiment, students in grades 3-8 from one school district will then submit their backyard observations of Orion's limiting magnitude to the 2009 Globe at Night star hunt while small student teams concurrently quantify sky glow from each schoolyard with hand-held meters. After mapping their results and having classroom discussions, students will present their findings to the School Board. Material compiled and created for the program will be available for other dark sky advocates at www.LetThereBeNight.com, while large digital files will be distributed on disk through two planetarium associations. A 2008 Toyota TAPESTRY grant has enticed significant professional support, additional funding, and in-kind contributions.

Capsule physics comparison of National Ignition Facility implosion designs using plastic, high density carbon, and beryllium ablators

NASA Astrophysics Data System (ADS)

Clark, D. S.; Kritcher, A. L.; Yi, S. A.; Zylstra, A. B.; Haan, S. W.; Weber, C. R.

2018-03-01

Indirect drive implosion experiments on the National Ignition Facility (NIF) [E. I. Moses et al., Phys. Plasmas 16, 041006 (2009)] have now tested three different ablator materials: glow discharge polymer plastic, high density carbon, and beryllium. How do these different ablators compare in current and proposed implosion experiments on NIF? What are the relative advantages and disadvantages of each? This paper compares these different ablator options in capsule-only simulations of current NIF experiments and potential future designs. The simulations compare the impact of the capsule fill tube, support tent, and interface surface roughness for each case, as well as all perturbations in combination. According to the simulations, each ablator is impacted by the various perturbation sources differently, and each material poses unique challenges in the pursuit of ignition on NIF.

NICMOS Temperature-specific Darks

NASA Astrophysics Data System (ADS)

Monroe, B.; Bergeron, E.

1999-11-01

The various components of NICMOS dark images have been modeled and combined to make synthetic dark calibration files which are intended for use with observations in a temperature range from 61 to ~75 K, currently available only for camera 2, with cameras 1 and 3 to follow in a few months. The amplifier glow and the true linear dark current have been constructed as temperature-independent quantities, while the “shading” component of the darks has been modeled as temperature-dependent. The data used to construct these models was taken with NIC 2, in a temperature range of 61 to 80 K during the recent warm-up of NICMOS due to cryogen exhaustion. The resulting synthetic darks are available through a web-based tool on the STScI NICMOS website http://www.stsci.edu/instruments/nicmos/NICMOS_tools/syndark.html.

Deviation from Boltzmann distribution in excited energy levels of singly-ionized iron in an argon glow discharge plasma for atomic emission spectrometry

NASA Astrophysics Data System (ADS)

Zhang, Lei; Kashiwakura, Shunsuke; Wagatsuma, Kazuaki

2012-01-01

A Boltzmann plot for many iron ionic lines having excitation energies of 4.7-9.1 eV was investigated in an argon glow discharge plasma when the discharge parameters, such as the voltage/current and the gas pressure, were varied. A Grimm-style radiation source was employed in a DC voltage range of 400-800 V at argon pressures of 400-930 Pa. The plot did not follow a linear relationship over a wide range of the excitation energy, but it yielded a normal Boltzmann distribution in the range of 4.7-5.8 eV and a large overpopulation in higher-lying excitation levels of iron ion. A probable reason for this phenomenon is that excitations for higher excited energy levels of iron ion would be predominantly caused by non-thermal collisions with argon species, the internal energy of which is received by iron atoms for the ionization. Particular intense ionic lines, which gave a maximum peak of the Boltzmann plot, were observed at an excitation energy of ca. 7.7 eV. They were the Fe II 257.297-nm and the Fe II 258.111-nm lines, derived from the 3d54s4p 6P excited levels. The 3d54s4p 6P excited levels can be highly populated through a resonance charge transfer from the ground state of argon ion, because of good matching in the excitation energy as well as the conservation of the total spin before and after the collision. An enhancement factor of the emission intensity for various Fe II lines could be obtained from a deviation from the normal Boltzmann plot, which comprised the emission lines of 4.7-5.8 eV. It would roughly correspond to a contribution of the charge transfer excitation to the excited levels of iron ion, suggesting that the charge-transfer collision could elevate the number density of the corresponding excited levels by a factor of ca.104. The Boltzmann plots give important information on the reason why a variety of iron ionic lines can be emitted from glow discharge plasmas.

Surface oxygen micropatterns on glow discharge polymer targets by photo irradiation

DOE PAGES

Reynolds, Hannah; Baxamusa, Salmaan; Haan, Steven W.; ...

2016-02-24

Recent simulations predict surface oxygen may be a significant source of disruptive perturbations in the implosion process of glow-discharge polymers (GDP) ablators at the National Ignition Facility. GDP material held in ambient atmospheric conditions showed an increase in mass when stored in light transparent containers, which suggests that photo exposure is a driving force for oxygen absorption. To investigate if surface oxygen is a contributing factor of disruptive perturbations during implosion, we developed a method to imprint a periodic micropattern of oxygen on the surface of GDP and used it to fabricate a flat sample for empirical testing.

Gas temperature measurements in deuterium hollow cathode glow discharge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Majstorović, Gordana, E-mail: gordana.majstorovic@va.mod.gov.rs; Šišović, Nikola, E-mail: nikolas@ff.bg.ac.rs

2016-03-25

We report results of optical emission spectroscopy measurements of rotational T{sub rot} and translational (gas) temperature of deuterium molecules in a hollow cathode (HC) glow discharge. The rotational temperature of excited electronic state of D{sub 2} was determined from the intensity distribution in the rotational structure of Q branch of the two Fulcher-α diagonal bands: (ν’=ν”=2) and (ν’=ν”=3). The population of excited energy levels, determined from relative line intensities, was used to derive radial rotational temperature distributions as well as gas temperature distribution of deuterium molecule.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghosh, Sabuj, E-mail: sabuj.ghosh@saha.ac.in; Shaw, Pankaj Kumar, E-mail: pankaj.shaw@saha.ac.in; Saha, Debajyoti, E-mail: debajyoti.saha@saha.ac.in

2015-05-15

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.

LANL Transfers Glowing Bio Technology to Sandia Biotech

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rorick, Kevin; Nakhla, Tony; Pino, Tony

2012-05-21

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

LANL Transfers Glowing Bio Technology to Sandia Biotech

ScienceCinema

Rorick, Kevin; Nakhla, Tony; Pino, Tony; Hadley, David

2018-03-02

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

Composite Development and Applications for RLV Tankage

NASA Technical Reports Server (NTRS)

Wright, Richard J.; Achary, David C.; McBain, Michael C.

2003-01-01

The development of polymer composite cryogenic tanks is a critical step in creating the next generation of launch vehicles. Future launch vehicles need to minimize the gross liftoff weight (GLOW), which is possible due to the 28%-41% reduction in weight that composite materials can provide over current aluminum technology. The development of composite cryogenic tanks, feedlines, and unpressurized structures are key enabling technologies for performance and cost enhancements for Reusable Launch Vehicles (RLVs). The technology development of composite tanks has provided direct and applicable data for feedlines, unpressurized structures, material compatibility, and cryogenic fluid containment for highly loaded complex structures and interfaces. All three types of structure have similar material systems, processing parameters, scaling issues, analysis methodologies, NDE development, damage tolerance, and repair scenarios. Composite cryogenic tankage is the most complex of the 3 areas and provides the largest breakthrough in technology. A building block approach has been employed to bring this family of difficult technologies to maturity. This approach has built up composite materials, processes, design, analysis and test methods technology through a series of composite test programs beginning with the NASP program to meet aggressive performance goals for reusable launch vehicles. In this paper, the development and application of advanced composites for RLV use is described.

Coupling of multi-walled carbon nanotubes/polydimethylsiloxane coated stir bar sorptive extraction with pulse glow discharge-ion mobility spectrometry for analysis of triazine herbicides in water and soil samples.

PubMed

Zou, Nan; Yuan, Chunhao; Liu, Shaowen; Han, Yongtao; Li, Yanjie; Zhang, Jialei; Xu, Xiang; Li, Xuesheng; Pan, Canping

2016-07-29

An analytical method based on stir bar sorptive extraction (SBSE) coupled with pulse glow discharge-ion mobility spectrometry (PGD-IMS) was developed for analysis of three triazine pesticide residues in water and soil samples. An injection port with sealing device and stir bars hold device were designed and constructed to directly position the SBSE fiber including the extracted samples into the heating device, making desorption and detection of analytes proceeded simultaneously. The extraction conditions such as SBSE solid phase material, extraction time, extraction temperature, pH value and salt concentration were optimized. Mixture of MWCNTs-COOH and PDMS were shown to be effective in enriching the triazines. The LODs and LOQs of three triazines were found to be 0.006-0.015μgkg(-1) and 0.02-0.05μgkg(-1), and the linear range was 0.05-10μgL(-1) with determination coefficients from 0.9987 to 0.9993. The SBSE-PGD-IMS method was environmentally friendly without organic solvent consumption in the entire experimental procedures, and it was demonstrated to be a commendable rapid analysis technique for analysis of triazine pesticide residues in environmental samples on site. The proposed method was applied for the analysis of real ground water, surface water and soil samples. Copyright © 2016 Elsevier B.V. All rights reserved.

An Experiment to Detect Lunar Horizon Glow with the Lunar Orbit Laser Altimeter Laser Ranging Telescope

NASA Astrophysics Data System (ADS)

Smith, David E.; Zuber, Maria T.; Barker, Michael; Mazarico, Erwan; Neumann, Gregory A.; McClanahan, Timothy P.; Sun, Xiaoli

2016-04-01

Lunar horizon glow (LHG) was an observation by the Apollo astronauts of a brightening of the horizon around the time of sunrise. The effect has yet to be fully explained or confirmed by instruments on lunar orbiting spacecraft despite several attempts. The Lunar Reconnaissance Orbiter (LRO) spacecraft carries the laser altimeter (LOLA) instrument which has a 2.5 cm aperture telescope for Earth-based laser ranging (LR) mounted and bore-sighted with the high gain antenna (HGA). The LR telescope is connected to LOLA by a fiber-glass cable to one of its 5 detectors. For the LGH experiments the LR telescope is pointed toward the horizon shortly before lunar sunrise with the intent of observing any forward scattering of sunlight due to the presence of dust or particles in the field of view. Initially, the LR telescope is pointed at the dark lunar surface, which provides a measure of the dark count, and moves toward the lunar limb so as to measure the brightness of the sky just above the lunar limb immediately prior to lunar sunrise. At no time does the sun shine directly into the LR telescope, although the LR telescope is pointed as close to the sun as the 1.75-degree field of view permits. Experiments show that the LHG signal seen by the astronauts can be detected with a four-second integration of the noise counts.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mendoza-Lopez, M.L.; Centro de Fisica Aplicada y Tecnologia Avanzada, Departamento de Nanotecnologia, Universidad Nacional Autonoma de Mexico, Campus Juriquilla, Apdo. Postal 1-1010, Queretaro Qro. C.P. 76230; Perez-Bueno, J.J.

This paper presents a complete methodology for the characterization of silver alloys used in modern coin production. Mexican coins with a nominal silver concentration from 10% to 99.99% were used in this study. Calibrated Glow Discharge Optical Emission Spectrometers were used to determine the chemical composition of the alloys as a function of the depth, while inductively coupled plasma was used to determine the total element composition in bulk. Scanning Electron Microscope was used to study the phase distributions in the different silver coins. According to Glow Discharge Optical Emission Spectrometers and inductively coupled plasma, the silver content found inmore » the studied samples was consistently greater than that of the nominal silver content reported by the Mexican mint. This may lead to a review of the new methods of analysis used nowadays in contemporary coin minting. This result is very important because silver is increasing in value as metal and, considering the volume of production of silver coins, this may increase further as a consequence of a growing popular confidence in silver currency. In the case of silver studies, an advantage of the absence of silver detector in the Glow Discharge Optical Emission Spectrometers system is that it allows for the recalibration to have a better range of detection of other metals present in the alloys. A calibration curve using the copper content obtained by inductively coupled plasma (bulk) and Glow Discharge Optical Emission Spectrometers (depth profile) was performed. The relevance of control in modern silver coin minting was clarified, especially in minimizing the discrepancy between the nominal and the core fineness. The physical and chemical properties of the alloys studied are defined, revealing important variations in silver and copper contents. A new methodology and metrology for the control of coinage are suggested.« less

Light in Thermal Environments (LITE) Workshop

NASA Technical Reports Server (NTRS)

1993-01-01

Light emitted from high temperature black smokers (350 C) at mid-ocean ridge spreading centers has been documented, but the source of this light and its photochemical and biological consequences have yet to be investigated. Preliminary studies indicate that thermal radiation alone might account for the 'glow' and that a novel photoreceptor in shrimp colonizing black smoker chimneys may detect this 'glow.' A more controversial question is whether there may be sufficient photon flux of appropriate wavelengths to support geothermally-driven photosynthesis (GDP) by microorganisms. Although only a very low level of visible and near infrared light may be emitted from any single hydrothermal vent, several aspects of the light make it of more than enigmatic interest. First, the light is clearly linked to geophysical (and perhaps geochemical) processes; its attributes may serve as powerful index parameters for monitoring change in these processes. Second, while the glow at a vent orifice is a very local phenomenon, more expansive subsurface environments may be illuminated, thereby increasing the spatial scale at which biological consequences of this light might be considered. Third, in contrast to intermittent bioluminescent light sources in the deep sea, the light emitted at vents almost certainly glows or flickers continuously over the life of the individual black smokers (years to decades); collectively, light emitted from black smokers along the ocean's spreading centers superimposed on background Cerenkov radiation negates the concept of the deep sea as an environment devoid of abiotic light. Finally, the history of hydrothermal activity predates the origin of life; light in the deep sea has been a continuous phenomenon on a geological time scale and may have served either as a seed or refugium for the evolution of biological photochemical reactions or adaptations.

The Thermoluminescent Response of Several Phosphors to Monoenergetic Photon Beams with Energies from 275 TO 2,550 EV.

NASA Astrophysics Data System (ADS)

Carrillo Beltran, Ricardo Enrique

The thermoluminescent (TL) response of LiF:Mg,Ti (TLD-100) and CaF_2:Dy (TLD-200) to monoenergetic photon beams was measured for photons with energies between 275 and 2,550 eV produced by the Aladdin synchrotron accelerator of the UW-Madison. The change of the TL response, as measured by the 130-215 ^circC integrated light output for TLD-100, the 170-250^circC TL interval for TLD-200 and the height of the main dosimetric peak at 200^circC for both phosphors as a function of total energy deposited up to saturation is described. Glow curves were determined for TLDs annealed in helium and irradiated at various photon energies. Glow curves showing the adverse effect of air annealing upon the TL sensitivity of these phosphors are presented as well. Supralinearity factors for each TLD type were calculated using the integrated TL and the main peak height and are listed for the photon energy beams employed. High surface doses were achieved with these irradiations because of the short mean free path of the photons and the even shorter range of the freed electrons, both plotted. Despite the shallower penetration of the photons in TLD-200 as compared to TLD-100, the former phosphor was found to be more suitable for routine use as a synchrotron radiation monitor because its TL properties change very little with photon energy as shown by its constant glow curve obtained. TLD-100 glow curve, either from a chip or a crystal, changed according to the photon energy employed; this adverse effect was more pronounced with the chips.

Temperature dependent characteristics of a recombinant infectious hematopoietic necrosis virus glycoprotein produced in insect cells.

PubMed

Cain, K D; Byrne, K M; Brassfield, A L; LaPatra, S E; Ristow, S S

1999-04-15

A recombinant infectious hematopoietic necrosis virus (IHNV) glycoprotein (G protein) was produced in insect cells using a baculovirus vector (Autographa californica nuclear polyhedrosis virus). Characteristics of this protein were evaluated in relation to native viral G protein. A full-length (1.6 kb) cDNA copy of the glycoprotein gene of IHNV was inserted into the baculovirus vector under control of the polyhedrin promoter. High levels of G protein (approximately 0.5 microgram/1 x 10(5) cells) were produced in Spodoptera frugiperda (Sf9) cells following recombinant baculovirus infection. Analysis of cell lysates by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot revealed a recombinant IHNV G of slightly higher mobility on the gel than the viral G protein. Differences in mobility were abrogated by endoglycosidase treatment. When the recombinant G protein was produced in insect cells at 20 degrees C (RecGlow), immunostaining and cell fusion activity demonstrated surface localization of the protein. In contrast, when recombinant protein was produced at 27 degrees C (RecGhigh), G protein was sequestered within the cell, suggesting that at the 2 different temperatures processing differences may exist. Eleven monoclonal antibodies (MAbs) were tested by immunoblotting for reactivity to the recombinant G protein. All 11 MAbs reacted to the reduced proteins. Four MAbs recognized both RecGhigh and RecGlow under non-reducing conditions; however, 1 neutralizing MAb (92A) recognized RecGlow but failed to react to RecGhigh under non-reducing conditions. This suggests that differences exist between RecGlow and RecGhigh which may have implications in the development of a properly folded recombinant G protein with the ability to elicit protective immunity in fish.

Photoluminescence, thermoluminescence glow curve and emission characteristics of Y2O3:Er3+ nanophosphor.

PubMed

N J, Shivaramu; B N, Lakshminarasappa; K R, Nagabhushana; H C, Swart; Fouran, Singh

2018-01-15

Nanocrystalline Er 3+ doped Y 2 O 3 crystals were prepared by a sol gel technique. X-ray diffraction (XRD) patterns showed the cubic structure of Y 2 O 3 and the crystallite size was found to be ~25nm. Optical absorption showed absorption peaks at 454, 495 and 521nm. These peaks are attributed to the 4 F 3/2 + 4 F 5/2 , 4 F 7/2 and 2 H 11/2 + 4 S 3/2 transitions of Er 3+ . Under excitation at 378nm, the appearance of strong green (520-565nm) down conversion emission assigned to the ( 2 H 11/2, 4 S 3/2 )→ 4 I 15/2 transition and the feeble red (650-665nm) emission is assigned to the 4 F 9/2 → 4 I 15/2 transition. The color chromaticity coordinates showed emission in the green region. The strong green emission of Y 2 O 3 :Er 3+ nanophosphor may be useful for applications in solid compact laser devices. Thermoluminescence (TL) studies of γ-irradiated Y 2 O 3 :Er 3+ showed a prominent TL glow peak maximum at 383K along with a less intense shoulder peak at ~425K and a weak glow at 598K. TL emission peaks with maxima at 545, 490, 588 and 622nm for the doped sample were observed at a temperature of 383K and these emissions were due to defect related to the host material. TL kinetic parameters were calculated by a glow curve deconvolution (GCD) method and the obtained results are discussed in detail for their possible usage in high dose dosimetry. Copyright © 2017 Elsevier B.V. All rights reserved.

Pediatric and young adult exposure to chemiluminescent glow sticks.

PubMed

Hoffman, Robert J; Nelson, Lewis S; Hoffman, Robert S

2002-09-01

Although chemiluminescent plastic rods, commonly called "glow sticks" or "light sticks," are typically considered to be minimally toxic or nontoxic, published data about exposure to these products are scarce. To test our hypothesis that exposure to chemiluminescent products is unlikely to result in significant morbidity or mortality and to describe factors associated with exposure by reviewing reports to our urban poison control center of human exposure to chemiluminescent products. Pediatric and young adult exposure to chemiluminescent products reported between January 1, 2000, and April 1, 2001, to our poison control center were evaluated with regard to demographic group, type of product involved, circumstances of exposure, symptoms, and management. Reported routes of exposure (n = 118) included ingestion (n = 108), ocular (n = 9), and dermal exposure (n = 1). Only patients exposed to chemiluminescent fluid from a leaking container reported symptoms (n = 27). Symptoms were limited to transient irritation of the exposure site, and no systemic toxicity occurred. All adults (n = 4) inadvertently ruptured or swallowed intact light sticks while at a dance club or dance party. Most exposure and all adult exposure occurred on holidays or weekends. Most incidences of exposure to chemiluminescent products involve asymptomatic ingestion of fluid that leaks from glow sticks or ingestion of an intact glow stick. Symptoms occur after exposure to chemiluminescent fluid and consist of transient irritation at the site of exposure. The clustering of reported exposure on weekends and in dance clubs and parties coupled with a lack of occupational or workplace exposure suggest that recreational use is a major contributory factor. Exposure to chemiluminescent products infrequently resulted in symptoms and the symptoms reported were minor. Exposure to chemiluminescent products as described is unlikely to cause significant morbidity or mortality.

Photoluminescence, thermoluminescence glow curve and emission characteristics of Y2O3:Er3 + nanophosphor

NASA Astrophysics Data System (ADS)

N. J., Shivaramu; B. N., Lakshminarasappa; K. R., Nagabhushana; H. C., Swart; Fouran, Singh

2018-01-01

Nanocrystalline Er3 + doped Y2O3crystals were prepared by a sol gel technique. X-ray diffraction (XRD) patterns showed the cubic structure of Y2O3 and the crystallite size was found to be 25 nm. Optical absorption showed absorption peaks at 454, 495 and 521 nm. These peaks are attributed to the 4F3/2 + 4F5/2, 4F7/2 and 2H11/2 + 4S3/2 transitions of Er3 +. Under excitation at 378 nm, the appearance of strong green (520-565 nm) down conversion emission assigned to the (2H11/2,4S3/2) → 4I15/2 transition and the feeble red (650-665 nm) emission is assigned to the 4F9/2 → 4I15/2 transition. The color chromaticity coordinates showed emission in the green region. The strong green emission of Y2O3:Er3 + nanophosphor may be useful for applications in solid compact laser devices. Thermoluminescence (TL) studies of γ-irradiated Y2O3:Er3 + showed a prominent TL glow peak maximum at 383 K along with a less intense shoulder peak at 425 K and a weak glow at 598 K. TL emission peaks with maxima at 545, 490, 588 and 622 nm for the doped sample were observed at a temperature of 383 K and these emissions were due to defect related to the host material. TL kinetic parameters were calculated by a glow curve deconvolution (GCD) method and the obtained results are discussed in detail for their possible usage in high dose dosimetry.

Mycophenolate mofetil combined with systemic corticosteroids prevents progression to chronic recurrent inflammation and development of 'sunset glow fundus' in initial-onset acute uveitis associated with Vogt-Koyanagi-Harada disease.

PubMed

Abu El-Asrar, Ahmed M; Dosari, Mona; Hemachandran, Suhail; Gikandi, Priscilla W; Al-Muammar, Abdulrahman

2017-02-01

To evaluate the effectiveness and safety of mycophenolate mofetil (MMF) as first-line therapy combined with systemic corticosteroids in initial-onset acute uveitis associated with Vogt-Koyanagi-Harada (VKH) disease. This prospective study included 38 patients (76 eyes). The main outcome measures were final visual acuity, corticosteroid-sparing effect, progression to chronic recurrent granulomatous uveitis and development of complications, particularly 'sunset glow fundus'. The mean follow-up period was 37.0 ± 29.3 (range 9-120 months). Visual acuity of 20/20 was achieved by 93.4% of the eyes. Corticosteroid-sparing effect was achieved in all patients. The mean interval between starting treatment and tapering to 10 mg or less daily was 3.8 ± 1.3 months (range 3-7 months). Twenty-two patients (57.9%) discontinued treatment without relapse of inflammation. The mean time observed off of treatment was 28.1 ± 19.6 months (range 1-60 months). None of the eyes progressed to chronic recurrent granulomatous uveitis. The ocular complications encountered were glaucoma in two eyes (2.6%) and cataract in five eyes (6.6%). None of the eyes developed 'sunset glow fundus', and none of the patients developed any systemic adverse events associated with the treatment. Use of MMF as first-line therapy combined with systemic corticosteroids in patients with initial-onset acute VKH disease prevents progression to chronic recurrent granulomatous inflammation and development of 'sunset glow fundus'. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Synthesis characterization and luminescence studies of gamma irradiated nanocrystalline yttrium oxide

NASA Astrophysics Data System (ADS)

Shivaramu, N. J.; Lakshminarasappa, B. N.; Nagabhushana, K. R.; Singh, Fouran

2016-02-01

Nanocrystalline Y2O3 is synthesized by solution combustion technique using urea and glycine as fuels. X-ray diffraction (XRD) pattern of as prepared sample shows amorphous nature while annealed samples show cubic nature. The average crystallite size is calculated using Scherrer's formula and is found to be in the range 14-30 nm for samples synthesized using urea and 15-20 nm for samples synthesized using glycine respectively. Field emission scanning electron microscopy (FE-SEM) image of 1173 K annealed Y2O3 samples show well separated spherical shape particles and the average particle size is found to be in the range 28-35 nm. Fourier transformed infrared (FTIR) and Raman spectroscopy reveals a stretching of Y-O bond. Electron spin resonance (ESR) shows V- center, O2- and Y2 + defects. A broad photoluminescence (PL) emission with peak at 386 nm is observed when the sample is excited with 252 nm. Thermoluminescence (TL) properties of γ-irradiated Y2O3 nanopowder are studied at a heating rate of 5 K s- 1. The samples prepared by using urea show a prominent and well resolved peak at 383 K and a weak one at 570 K. It is also found that TL glow peak intensity (Im1) at 383 K increases with increase in γ-dose up to 6.0 kGy and then decreases with increase in dose. However, glycine used Y2O3 shows a prominent TL glow with peaks at 396 K and 590 K. Among the fuels, urea used Y2O3 shows simple and well resolved TL glows. This might be due to fuel and hence particle size effect. The kinetic parameters are calculated by Chen's glow curve peak shape method and results are discussed in detail.

Stacking the Cosmic Web in fluorescent Ly α emission with MUSE

NASA Astrophysics Data System (ADS)

Gallego, Sofia G.; Cantalupo, Sebastiano; Lilly, Simon; Marino, Raffaella Anna; Pezzulli, Gabriele; Schaye, Joop; Wisotzki, Lutz; Bacon, Roland; Inami, Hanae; Akhlaghi, Mohammad; Tacchella, Sandro; Richard, Johan; Bouche, Nicolas F.; Steinmetz, Matthias; Carollo, Marcella

2018-04-01

Cosmological simulations suggest that most of the matter in the Universe is distributed along filaments connecting galaxies. Illuminated by the cosmic UV background (UVB), these structures are expected to glow in fluorescent Ly α emission with a surface brightness (SB) that is well below current limits for individual detections. Here, we perform a stacking analysis of the deepest MUSE/VLT data using three-dimensional regions (subcubes) with orientations determined by the position of neighbouring Ly α galaxies at 3 < z < 4. Our method increase the probability of detecting filamentary Ly α emission, provided that these structures are Lyman-limit systems (LLSs). By stacking 390 oriented subcubes we reach a 2σ sensitivity level of SB ≈ 0.44 × 10-20 erg s-1 cm-2 arcsec-2 in an aperture of 1 arcsec2 × 6.25 Å, three times below the expected fluorescent Ly α signal from the Haardt & Madau UVB at z ˜ 3.5. No detectable emission is found on intergalactic scales, implying that at least two thirds of our subcubes do not contain oriented LLSs. On the other hand, significant emission is detected in the circumgalactic medium (CGM) in the direction of the neighbours. The signal is stronger for galaxies with a larger number of neighbours and appears to be independent of any other galaxy properties. We estimate that preferentially oriented satellite galaxies cannot contribute significantly to this signal, suggesting instead that gas densities in the CGM are typically larger in the direction of neighbouring galaxies on cosmological scales.

Mechanism of formation of subnanosecond current front in high-voltage pulse open discharge

NASA Astrophysics Data System (ADS)

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

2014-11-01

The mechanism of subnanosecond current front rise observed previously in the experiment in high-voltage pulse open discharge in helium is studied in kinetic particle-in-cell simulations. The Boltzmann equations for electrons, ions, and fast atoms are solved self-consistently with the Poisson equations for the electrical potential. The partial contributions to the secondary electron emission from the ions, fast atoms, photons, and electrons, bombarding the electrode, are calculated. In simulations, as in the experiment, the discharge glows between two symmetrical cathodes and the anode grid in the midplane at P =6 Torr and the applied voltage of 20 kV. The electron avalanche development is considered for two experimental situations during the last stage of breakdown: (i) with constant voltage and (ii) with decreasing voltage. For case (i), the subnanosecond current front rise is set by photons from the collisional excitation transfer reactions. For the case (ii), the energetic electrons swamp the cathode during voltage drop and provide the secondary electron emission for the subnanosecond current rise, observed in the experiment.

Bifurcations in the theory of current transfer to cathodes of DC discharges and observations of transitions between different modes

NASA Astrophysics Data System (ADS)

Bieniek, M. S.; Santos, D. F. N.; Almeida, P. G. C.; Benilov, M. S.

2018-04-01

General scenarios of transitions between different spot patterns on electrodes of DC gas discharges and their relation to bifurcations of steady-state solutions are analyzed. In the case of cathodes of arc discharges, it is shown that any transition between different modes of current transfer is related to a bifurcation of steady-state solutions. In particular, transitions between diffuse and spot modes on axially symmetric cathodes, frequently observed in the experiment, represent an indication of the presence of pitchfork or fold bifurcations of steady-state solutions. Experimental observations of transitions on cathodes of DC glow microdischarges are analyzed and those potentially related to bifurcations of steady-state solutions are identified. The relevant bifurcations are investigated numerically and the computed patterns are found to conform to those observed in the course of the corresponding transitions in the experiment.

Capsule physics comparison of different ablators for NIF implosion designs

NASA Astrophysics Data System (ADS)

Clark, Daniel; Kritcher, Andrea; Yi, Austin; Zylstra, Alex; Haan, Steven; Ralph, Joseph; Weber, Christopher

2017-10-01

Indirect drive implosion experiments on the Naitonal Ignition Facility (NIF) have now tested three different ablator materials: glow discharge polymer (GDP) plastic, high density carbon (HDC), and beryllium. How do these different ablator choices compare in current and future implosion experiments on NIF? What are the relative advantages and disadvantages of each? This talk compares these different ablator options in capsule-only simulations of current NIF experiments and proposed future designs. The simulations compare the impact of the capsule fill tube, support tent, and interface surface roughness for each case, as well as all perturbations in combination. According to the simulations, each ablator is impacted by the various perturbation sources differently, and each material poses unique challenges in the pursuit of ignition. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Magnetron cathodes in plasma electrode Pockels cells

DOEpatents

Rhodes, M.A.

1995-04-25

Magnetron cathodes, which produce high current discharges, form greatly improved plasma electrodes on each side of an electro-optic crystal. The plasma electrode has a low pressure gas region on both sides of the crystal. When the gas is ionized, e.g., by a glow discharge in the low pressure gas, the plasma formed is a good conductor. The gas electrode acts as a highly uniform conducting electrode. Since the plasma is transparent to a high energy laser beam passing through the crystal, the plasma is transparent. A crystal exposed from two sides to such a plasma can be charged up uniformly to any desired voltage. A typical configuration utilizes helium at 50 millitorr operating pressure and 2 kA discharge current. The magnetron cathode produces a more uniform plasma and allows a reduced operating pressure which leads to lower plasma resistivity and a more uniform charge on the crystal. 5 figs.

Magnetron cathodes in plasma electrode pockels cells

DOEpatents

Rhodes, Mark A.

1995-01-01

Magnetron cathodes, which produce high current discharges, form greatly improved plasma electrodes on each side of an electro-optic crystal. The plasma electrode has a low pressure gas region on both sides of the crystal. When the gas is ionized, e.g., by a glow discharge in the low pressure gas, the plasma formed is a good conductor. The gas electrode acts as a highly uniform conducting electrode. Since the plasma is transparent to a high energy laser beam passing through the crystal, the plasma is transparent. A crystal exposed from two sides to such a plasma can be charged up uniformly to any desired voltage. A typical configuration utilizes helium at 50 millitorr operating. pressure and 2 kA discharge current. The magnetron cathode produces a more uniform plasma and allows a reduced operating pressure which leads to lower plasma resistivity and a more uniform charge on the crystal.

Thermoluminescence of nanocrystalline CaSO{sub 4}: Dy for gamma dosimetry and calculation of trapping parameters using deconvolution method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mandlik, Nandkumar, E-mail: ntmandlik@gmail.com; Patil, B. J.; Bhoraskar, V. N.

2014-04-24

Nanorods of CaSO{sub 4}: Dy having diameter 20 nm and length 200 nm have been synthesized by the chemical coprecipitation method. These samples were irradiated with gamma radiation for the dose varying from 0.1 Gy to 50 kGy and their TL characteristics have been studied. TL dose response shows a linear behavior up to 5 kGy and further saturates with increase in the dose. A Computerized Glow Curve Deconvolution (CGCD) program was used for the analysis of TL glow curves. Trapping parameters for various peaks have been calculated by using CGCD program.

Thermoluminescence of nanocrystalline CaSO4: Dy for gamma dosimetry and calculation of trapping parameters using deconvolution method

NASA Astrophysics Data System (ADS)

Mandlik, Nandkumar; Patil, B. J.; Bhoraskar, V. N.; Sahare, P. D.; Dhole, S. D.

2014-04-01

Nanorods of CaSO4: Dy having diameter 20 nm and length 200 nm have been synthesized by the chemical coprecipitation method. These samples were irradiated with gamma radiation for the dose varying from 0.1 Gy to 50 kGy and their TL characteristics have been studied. TL dose response shows a linear behavior up to 5 kGy and further saturates with increase in the dose. A Computerized Glow Curve Deconvolution (CGCD) program was used for the analysis of TL glow curves. Trapping parameters for various peaks have been calculated by using CGCD program.

Synergism between low-energy neutral particles and energetic ions in the pulsed glow discharge deposition of diamond-like carbon films

NASA Astrophysics Data System (ADS)

Afanasyev-Charkin, I. V.; Nastasi, M.

2004-08-01

Diamond-like carbon films were deposited using pulsed glow discharge deposition at 4kV. The duty factor was varied and all other parameters were kept constant. It was shown that the contribution of neutral particles to the total number of deposition atoms is much larger than that of energetic ions. At the same time, there is a relationship between the deposition of neutral particles and ion bombardment. The sticking coefficient of the neutral particles in proportional to the flux of energetic ions and does not exceed 5×10-4 for the deposition parameters used in our experiment.

Reproducing continuous radio blackout using glow discharge plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xie, Kai; Li, Xiaoping; Liu, Donglin

2013-10-15

A novel plasma generator is described that offers large-scale, continuous, non-magnetized plasma with a 30-cm-diameter hollow structure, which provides a path for an electromagnetic wave. The plasma is excited by a low-pressure glow discharge, with varying electron densities ranging from 10{sup 9} to 2.5 × 10{sup 11} cm{sup −3}. An electromagnetic wave propagation experiment reproduced a continuous radio blackout in UHF-, L-, and S-bands. The results are consistent with theoretical expectations. The proposed method is suitable in simulating a plasma sheath, and in researching communications, navigation, electromagnetic mitigations, and antenna compensation in plasma sheaths.

Comparison of plasma generated nitrogen fertilizer to conventional fertilizers ammonium nitrate and sodium nitrate for pre-emergent and seedling growth

NASA Astrophysics Data System (ADS)

Andhavarapu, A.; King, W.; Lindsay, A.; Byrns, B.; Knappe, D.; Fonteno, W.; Shannon, S.

2014-10-01

Plasma source generated nitrogen fertilizer is compared to conventional nitrogen fertilizers in water for plant growth. Root, shoot sizes, and weights are used to examine differences between plant treatment groups. With a simple coaxial structure creating a large-volume atmospheric glow discharge, a 162 MHz generator drives the air plasma. The VHF plasma source emits a steady state glow; the high drive frequency is believed to inhibit the glow-to-arc transition for non-thermal discharge generation. To create the plasma activated water (PAW) solutions used for plant treatment, the discharge is held over distilled water until a 100 ppm nitrate aqueous concentration is achieved. The discharge is used to incorporate nitrogen species into aqueous solution, which is used to fertilize radishes, marigolds, and tomatoes. In a four week experiment, these plants are watered with four different solutions: tap water, dissolved ammonium nitrate DI water, dissolved sodium nitrate DI water, and PAW. Ammonium nitrate solution has the same amount of total nitrogen as PAW; sodium nitrate solution has the same amount of nitrate as PAW. T-tests are used to determine statistical significance in plant group growth differences. PAW fertilization chemical mechanisms are presented.

The Improvement of Ion Plated Ag and Au Film Adherence to Si3N4 and SiC Surfaces for Increased Tribological Performance

NASA Technical Reports Server (NTRS)

Spalvins, Talivaldis

1998-01-01

A modified dc-diode plating system, utilizing a metallic screen cage as a cathode and referred as SCREEN CAGE ION PLATING (SCIP), is used to deposit Ag and Au lubricating films on Si3N4 and SiC surfaces. When deposition is performed in Ar or N2, glow discharge, the surface displays poor adhesive strength (less than 5 MPa). A dramatic increase in adhesive strength (less than 80 MPa) is achieved when plating is performed in a reactive 50% 02 + 50% Ar glow discharge. The excited/ionized oxygen species (O2(+)/O(+) in the glow discharge contribute to the oxidation of the Si3N4 or SiC surfaces as determined by X-ray Photoelectron Spectroscopy (XTS) depth profiling. The reactively sputter-oxidized S3N4 or SiC surfaces and the activated-oxidized-metastable Ag or Au species formed in the plasma cooperatively contribute to the increased adherence. As a result, the linear thermal expansion coefficient mismatch at the interface is reduced. These lubricating Ag and Au films under sliding conditions reduce the friction coefficient by a factor of 2-1/2 to 4.

Effect of heating rate on thermoluminescence output of LiF: Mg, Ti (TLD-100) in dosimetric applications

NASA Astrophysics Data System (ADS)

Singh, Ranjit; Kainth, Harpreet Singh

2018-07-01

The luminiscence characteristics of thermoluminscence dosimeter LiF: Mg, Ti (TLD-100) irradiated to X-rays from 6 MV linac have been studied for wide range of 2-50 K/s readout linear heating rates. The reproducibility of glow curves for TLDs is found to be better at lower heating rates and depreciate at higher heating rates. The glow curve spectra were analysed using deconvolution procedure based on general-order kinetics. Shift in the peak maximum temperature per unit rise in heating rate for various peaks were found to decrease with heating rate. The TLDs irradiated with same dose exhibit decreasing TL counts with increase in the heating rate, which indicate the thermal quenching effect in TLD-100. The value of activation energy for each peak within the glow curve increases with heating rate. Calibration curves plotted for the dose range 0.4-1020 cGy exhibit decreasing slope with increasing readout heating rate. Corrections for temperature lag between the heating element and the dosimeter, and the effective heating rate (βeff) across the sample estimated using formulation proposed by Kitis and Tuyn and are found to be fairly applicable.

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.

Corrosion resistance improvement for 316L stainless steel coronary artery stents by trimethylsilane plasma nanocoatings.

PubMed

Eric Jones, John; Chen, Meng; Yu, Qingsong

2014-10-01

To improve their corrosion resistance and thus long-term biocompatibility, 316L stainless steel coronary artery stents were coated with trimethylsilane (TMS) plasma coatings of 20-25 nm in thickness. Both direct current (DC) and radio-frequency (RF) glow discharges were utilized for TMS plasma coatings and additional NH₃/O₂ plasma treatment to tailor the surface properties. X-ray photoelectron spectroscopy (XPS) was used to characterize the coating surface chemistry. It was found that both DC and RF TMS plasma coatings had Si- and C-rich composition, and the O- and N-contents on the surfaces were substantially increased after NH₃/O₂ plasma treatment. Surface contact angle measurements showed that DC TMS plasma nanocoating with NH₃/O₂ plasma treatment generated very hydrophilic surface. The corrosion resistance of TMS plasma coated stents was evaluated through potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The potentiodynamic polarization demonstrated that the TMS plasma coated stents imparted higher corrosion potential and pitting potential, as well as lower corrosion current densities as compared with uncoated controls. The surface morphology of stents before and after potentiodynamic polarization testing was analyzed with scanning electron microscopy, which indicated less corrosion on coated stents than uncoated controls. It was also noted that, from EIS data, the hydrophobic TMS plasma nanocoatings showed stable impedance modulus at 0.1 Hz after 21 day immersion in an electrolyte solution. These results suggest improved corrosion resistance of the 316L stainless steel stents by TMS plasma nanocoatings and great promise in reducing and blocking metallic ions releasing into the bloodstream. © 2014 Wiley Periodicals, Inc.

On electron bunching and stratification of glow discharges

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

2013-10-15

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 glowmore » 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.« less

Atomic hydrogen as a launch vehicle propellant

NASA Technical Reports Server (NTRS)

Palaszewski, Bryan A.

1990-01-01

An analysis of several atomic hydrogen launch vehicles was conducted. A discussion of the facilities and the technologies that would be needed for these vehicles is also presented. The Gross Liftoff Weights (GLOW) for two systems were estimated; their specific impulses (I sub sp) were 750 and 1500 lb(sub f)/s/lb(sub m). The atomic hydrogen launch vehicles were also compared to the currently planned Advanced Launch System design concepts. Very significant GLOW reductions of 52 to 58 percent are possible over the Advanced Launch System designs. Applying atomic hydrogen propellants to upper stages was also considered. Very high I(sub sp) (greater than 750 lb(sub f)/s/lb(sub m)) is needed to enable a mass savings over advanced oxygen/hydrogen propulsion. Associated with the potential benefits of high I(sub sp) atomic hydrogen are several challenging problems. Very high magnetic fields are required to maintain the atomic hydrogen in a solid hydrogen matrix. The magnetic field strength was estimated to be 30 kilogauss (3 Tesla). Also the storage temperature of the propellant is 4 K. This very low temperature will require a large refrigeration facility for the launch vehicle. The design considerations for a very high recombination rate for the propellant are also discussed. A recombination rate of 210 cm/s is predicted for atomic hydrogen. This high recombination rate can produce very high acceleration for the launch vehicle. Unique insulation or segmentation to inhibit the propellant may be needed to reduce its recombination rate.

The Electrostatic Environments of the Moon and Mars: Implications for Human Missions

NASA Technical Reports Server (NTRS)

Calle, Carlos I.; Mackey, Paul J.; Johansen, Michael R.; Hogue, Michael D.; Phillips, James; Cox, Rachel E.

2016-01-01

Lacking a substantial atmosphere, the moon is exposed to the full spectrum of solar radiation as well as to cosmic rays. Electrostatically, the moon is a charged body in a plasma. A Debye sheet meters high on the dayside of the moon and kilometers high on the night side envelops the moon. This sheet isolates the lunar surface from high energy particles coming from the sun. The electrostatic environment on Mars is controlled by its ever present atmospheric dust. Dust devils and dust storms tribocharge this dust. Theoretical studies predict that lightning and/or glow discharges should be present on Mars, but none have been directly observed. Experiments are planned to shed light on this issue.

Development of Techniques to Investigate Sonoluminescence as a Source of Energy Harvesting

NASA Technical Reports Server (NTRS)

Wrbanek, John D.; Fralick, Gustave C.; Wrbanek, Susan Y.

2007-01-01

Instrumentation techniques are being developed at NASA Glenn Research Center to measure optical, radiation, and thermal properties of the phenomena of sonoluminescence, the light generated using acoustic cavitation. Initial efforts have been directed to the generation of the effect and the imaging of the glow in water and solvents. Several images have been produced of the effect showing the location within containers, without the additions of light enhancers to the liquid. Evidence of high energy generation in the modification of thin films from sonoluminescence in heavy water was seen that was not seen in light water. Bright, localized sonoluminescence was generated using glycerin for possible applications to energy harvesting. Issues to be resolved for an energy harvesting concept will be addressed.

Method and apparatus for generating coherent near 14 and near 16 micron radiation

DOEpatents

Krupke, William F.

1977-01-01

A method and apparatus for producing coherent radiation in CO.sub.2 vibrational-rotational transitions at wavelengths near 14 and 16 microns. This is accomplished by passing a mixture of N.sub.2 and Ar through a glow discharge producing a high vibrational temperature in the N.sub.2, passing the excited N.sub.2 through a nozzle bank creating a supersonic flow thereof, injecting the CO.sub.2 in the supersonic flow creating a population inversion in the CO.sub.2, and directing the saturating pulse of radiation near 10.6 or 9.6 microns into the excited CO.sub.2 creating a population inversion producing coherent radiation at 14 or 16 microns, respectively.

Characterization and Performance of a High-Current-Density Ion Implanter with Magnetized Hollow-Cathode Plasma Source

NASA Astrophysics Data System (ADS)

Falkenstein, Zoran; Rej, Donald; Gavrilov, Nikolai

1998-10-01

In a collaboration between the Institute of Electrophysics (IEP) and the Los Alamos National Laboratory (LANL), the IEP has developed an industrial scalable, high-power, large-area ion source for the surface modification of materials. The plasma source of the ion beam source can be described as a pulsed glow discharge with a cold, hollow-cathode in a weak magnetic field. Extraction and focusing of positive ions by an acceleration and ion-optical plate system renders the generation of a homogeneous, large-area ion beam with an averaged total ion current of up to 50 mA at acceleration voltages of up to 50 kV. The principle set-up of the ion beam source as well as some electrical characteristics (gas discharge current and the extracted ion beam current) are presented for a lab-scale prototype. Measurements of the radial ion current density profiles within the ion beam for various discharge parameters, as well as results on surface modification by ion implantation of nitrogen into aluminum and chromium are presented. Finally, a comparison of the applied ion dose with the retained ion doses is given.

Ion Source Development at the SNS

NASA Astrophysics Data System (ADS)

Welton, R. F.; Stockli, M. P.; Murray, S. N.; Carr, J.; Carmichael, J.; Goulding, R. H.; Baity, F. W.

2007-08-01

The US Spallation Neutron Source (SNS) has recently begun producing neutrons and is currently on track to becoming a world-leading facility for material science based on neutron scattering. The facility is comprised of an H- ion source, a linear accelerator, an accumulator ring, a liquid-Hg target and a suite of neutron scattering instruments. Over the next several years the average H- current from the ion source will be increased in order to meet the baseline facility requirement of providing 1.4 MW of beam-power to the target and the SNS power upgrade power requirement of 2+ MW on target. Meeting the latter goal will require H- currents of 70-100 mA with an RMS emittance of 0.20-0.35 π mm mrad and a ˜7% duty-factor. To date, the RF-driven-multicusp SNS ion source has only been able to demonstrate sustained operation at 33 mA of beam current at a ˜7% duty-factor. This report details our efforts to develop variations of the current ion source which can meet these requirements. Designs and experimental results are presented for helicon plasma drivers, high-power external antennas, glow-discharge plasma guns and advanced Cs systems.

Data-driven local-scale modeling of ionospheric responses to auroral forcing using incoherent scatter radar and ground-based imaging measurements

NASA Astrophysics Data System (ADS)

Grubbs, G. A., II; Zettergren, M. D.; Samara, M.; Michell, R.; Hampton, D. L.; Lynch, K. A.; Varney, R. H.; Reimer, A.; Burleigh, M.

2017-12-01

The aurora encapsulates a wide range of spatial and temporal scale sizes, particularly during active events such as those that exist during substorm expansion. Of interest to the present work are ionospheric responses to magnetospheric forcing at relatively small scales (0.5-20 km), including formation of structured auroral arc current systems, ion frictional heating, upflow, and density cavity formation among other processes. Even for carefully arranged experiments, it is often difficult to fully assess physical details (time evolution, causality, unobservable parameters) associated with these types of responses, thus highlighting the general need for high-resolution modeling efforts to support the observations. In this work, we develop and test a local-scale model to describe effects of precipitating electrons and electric fields on the ionospheric plasma responses using available remote sensing data (e.g. from ISRs and filtered cameras). Our model is based on a 3D multi-fluid/electrostatic ionospheric model, GEMINI (Zettergren et al., 2015), coupled a two-stream electron transport code which produces auroral intensities, impact ionization, and thermal electron heating GLobal airglOW (GLOW; Solomon, 2017). GEMINI-GLOW thus describes both thermal and suprathermal effects on the ionosphere and is driven by boundary conditions consisting of topside ionospheric field-aligned currents and suprathermal electrons. These boundary conditions are constrained using time and space-dependent electric field and precipitation estimates from recent sounding rocket campaigns, ISINGLASS (02 March 2017) and GREECE (03 March 2014), derived from the Poker Flat incoherent scatter radar (PFISR) drifts and filtered EMCCD cameras respectively. Results from these data-driven case studies are compared to plasma parameter responses (i.e. density and temperature) independently estimated by PFISR and from the sounding rockets. These studies are intended as a first step towards a local-scale assimilative modeling approach where data-derived information will be fed back into the model to update the system state.

On the anomalous afterglow seen in a chameleon afterglow search

DOE Office of Scientific and Technical Information (OSTI.GOV)

Steffen, Jason H.; Baumbaugh, Alan; Chou, Aaron S.

2012-05-01

We present data from our investigation of the anomalous orange-colored afterglow that was seen in the GammeV Chameleon Afterglow Search (CHASE). These data include information about the broadband color of the observed glow, the relationship between the glow and the temperature of the apparatus, and other data taken prior to, and during the science operations of CHASE. While differing in several details, the generic properties of the afterglow from CHASE are similar to luminescence seen in some vacuum compounds. Contamination from this, or similar, luminescent signatures will likely impact the design of implementation of future experiments involving single photon detectorsmore » and high intensity light sources in a cryogenic environment.« less

Thermoluminescence and photoluminescence of cerium doped CaSO 4 nanosheets

NASA Astrophysics Data System (ADS)

Zahedifar, M.; Mehrabi, M.

2010-12-01

Thermoluminescence (TL) and photoluminescence (PL) characteristics of CaSO 4:Ce nanocrystalline prepared by hydrothermal method has been studied. Its TL glow curve contains three overlapping glow peaks at around 490, 505 and 521 K. Emission spectra band at 303 and 324 nm were observed for the orthorhombic phase of nanosheets. TL response of the prepared nanocrystalline to β and γ radiation was studied and the sensitivity of the nanosheets was found much more than that of analogous microcrystalline and is around 10 times higher than the well known high sensitive TL dosimeter LiF:Mg, Cu, P (GR-200) hot-pressed chips. TL kinetic parameters of this nanocrystalline are also presented.

Pseudoinefficacy: negative feelings from children who cannot be helped reduce warm glow for children who can be helped.

PubMed

Västfjäll, Daniel; Slovic, Paul; Mayorga, Marcus

2015-01-01

In a great many situations where we are asked to aid persons whose lives are endangered, we are not able to help everyone. What are the emotional and motivational consequences of "not helping all"? In a series of experiments, we demonstrate that negative affect arising from children that could not be helped decreases the warm glow of positive feeling associated with aiding the children who can be helped. This demotivation from the children outside of our reach may be a form of "pseudoinefficacy" that is non-rational. We should not be deterred from helping whomever we can because there are others we are not able to help.

Alignment relaxation of Ne*(2pi [J = 1]) atoms in He-Ne* glow discharges

NASA Astrophysics Data System (ADS)

Bahrim, Cristian; Khadilkar, Vaibhav; Matsukuma, Hiraku; Hasuo, Masahiro

2009-11-01

Alignment relaxation of the Ne*(2p5 3p; 2pi [J = 1]) atoms (where i = 2, 5, 7 or 10) induced by collisions with He atoms in glow discharges at 77 K < T < 1,000 K are reported. Close-coupling many-channel quantum calculations using a model potential for the Ne*(2p5 3p) - He system are compared with measurements of the alignment relaxation using the LIFS technique and the Hanle effect. The addition of the dipole polarization potential of the Ne*(2pi [J = 1]) atoms to the spin-orbit coupling and the electrostatic interaction between Ne* and He atoms leads to good agreement between theory and experiment.

Transport Equations Resolution By N-BEE Anti-Dissipative Scheme In 2D Model Of Low Pressure Glow Discharge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kraloua, B.; Hennad, A.

The aim of this paper is to determine electric and physical properties by 2D modelling of glow discharge low pressure in continuous regime maintained by term constant source. This electric discharge is confined in reactor plan-parallel geometry. This reactor is filled by Argon monatomic gas. Our continuum model the order two is composed the first three moments the Boltzmann's equations coupled with Poisson's equation by self consistent method. These transport equations are discretized by the finite volumes method. The equations system is resolved by a new technique, it is about the N-BEE explicit scheme using the time splitting method.

Elongated dust particles growth in a spherical glow discharge in ethanol

NASA Astrophysics Data System (ADS)

Fedoseev, A. V.; Sukhinin, G. I.; Sakhapov, S. Z.; Zaikovskii, A. V.; Novopashin, S. A.

2018-01-01

The formation of elongated dust particles in a spherical dc glow discharge in ethanol was observed for the first time. Dust particles were formed in the process of coagulation of ethanol dissociation products in the plasma of gas discharge. During the process the particles were captured into clouds in the electric potential wells of strong striations of spherical discharge. The size and the shape of dust particles are easily detected by naked eye after the illumination of the laser sheet. The description of the experimental setup and conditions, the analysis of size, shape and composition of the particles, the explanation of spatial ordering and orientation of these particles are presented.

Hugoniot equation of state of Si-doped glow discharge polymer and scaling to other plastic ablators

NASA Astrophysics Data System (ADS)

Huser, G.; Ozaki, N.; Colin-Lalu, P.; Recoules, V.; Sano, T.; Sakawa, Y.; Miyanishi, K.; Kodama, R.

2018-05-01

Pressure, density, and temperature were measured along the principal Hugoniot of the Si-doped Glow Discharge Polymer used in Inertial Confinement Fusion (ICF) capsules up to 5 Mbar, covering conditions beyond the first shock in a full-scale Inertial Confinement Fusion (ICF) capsule. The experiments were performed using the GEKKOXII laser at the Institute of Laser Engineering at Osaka University in Japan. Results are in good agreement with predictions obtained from ab initio Hugoniot calculations, but softer than the quotidian equation of state average atom model. Ab initio calculations show that dissociation of carbon bonds need to be taken into account in order to explain Hugoniot compressibility.

Atmospheric-pressure electric discharge as an instrument of chemical activation of water solutions

NASA Astrophysics Data System (ADS)

Rybkin, V. V.; Shutov, D. A.

2017-11-01

Results of experimental studies and numerical simulations of physicochemical characteristics of plasmas generated in different types of atmospheric-pressure discharges (pulsed streamer corona, gliding electric arc, dielectric barrier discharge, glow-discharge electrolysis, diaphragmatic discharge, and dc glow discharge) used to initiate various chemical processes in water solutions are analyzed. Typical reactor designs are considered. Data on the power supply characteristics, plasma electron parameters, gas temperatures, and densities of active particles in different types of discharges excited in different gases and their dependences on the external parameters of discharges are presented. The chemical composition of active particles formed in water is described. Possible mechanisms of production and loss of plasma particles are discussed.

Mercury Sodium Tail

NASA Image and Video Library

2015-04-16

This image from NASA MESSENGER spacecraft is stitched together from thousands of observations made over the past 4 years by the MASCS/UVVS instrument, which measures sunlight scattered off of Mercury tenuous atmosphere. Scattered sunlight gives the sodium a bright orange glow. This scattering process also gives sodium atoms a push - this "radiation pressure" is strong enough, during parts of Mercury's year, to strip the atmosphere and give Mercury a long glowing tail. Someone standing on Mercury's nightside at the right time of year would see a faint orange similar to a city sky illuminated by sodium lamps! Instrument: Mercury Atmospheric and Surface Composition Spectrometer (MASCS)/Ultraviolet and Visible Spectrometer (UVVS) http://photojournal.jpl.nasa.gov/catalog/PIA19418

Compensated amorphous silicon solar cell

DOEpatents

Devaud, Genevieve

1983-01-01

An amorphous silicon solar cell including an electrically conductive substrate, a layer of glow discharge deposited hydrogenated amorphous silicon over said substrate and having regions of differing conductivity with at least one region of intrinsic hydrogenated amorphous silicon. The layer of hydrogenated amorphous silicon has opposed first and second major surfaces where the first major surface contacts the electrically conductive substrate and an electrode for electrically contacting the second major surface. The intrinsic hydrogenated amorphous silicon region is deposited in a glow discharge with an atmosphere which includes not less than about 0.02 atom percent mono-atomic boron. An improved N.I.P. solar cell is disclosed using a BF.sub.3 doped intrinsic layer.

Study of surface atmospheric pressure glow discharge plasma based on ultrathin laminated electrodes in air

NASA Astrophysics Data System (ADS)

Zhao, Luxiang; Liu, Wenzheng; Li, Zhiyi; Ma, Chuanlong

2018-05-01

A method to generate large-area surface plasma in air by micro-discharge is proposed. Two ultrathin laminated electrode structures of non-insulating and insulating types were formed by using the nanoscale ITO conductive layer. The surface glow discharge in atmospheric air is realized in low discharge voltage by constructing the special electric field of two-dimensional unidirectional attenuation. In particular, the insulating electrode structure can avoid the loss of ITO electrodes so that the discharge stability can be increased, and the treated objects can be prevented from metal ion pollution caused by the electrode in the discharge. It has broad application prospects in the fields of aerodynamics and material surface treatment.

Secondary electron emission and glow discharge properties of 12CaO·7Al2O3 electride for fluorescent lamp applications.

PubMed

Watanabe, Satoru; Watanabe, Toshinari; Ito, Kazuhiro; Miyakawa, Naomichi; Ito, Setsuro; Hosono, Hideo; Mikoshiba, Shigeo

2011-06-01

12CaO·7Al 2 O 3 electride, a sub-nanoporous compound having a work function of 2.4 eV, was examined as a candidate cathode material in fluorescent lamps. The electron emission yield was higher and the discharge voltage was lower for 12CaO·7Al 2 O 3 than for existing cathode materials such as Ni, Mo or W; therefore, the energy consumption of the fluorescent lamps can be improved using 12CaO·7Al 2 O 3 cathodes. Prototype glow-discharge lamps using 12CaO·7Al 2 O 3 were constructed and exhibited reasonable durability.

Secondary electron emission and glow discharge properties of 12CaO·7Al2O3 electride for fluorescent lamp applications

PubMed Central

Watanabe, Satoru; Watanabe, Toshinari; Ito, Kazuhiro; Miyakawa, Naomichi; Ito, Setsuro; Hosono, Hideo; Mikoshiba, Shigeo

2011-01-01

12CaO·7Al2O3 electride, a sub-nanoporous compound having a work function of 2.4 eV, was examined as a candidate cathode material in fluorescent lamps. The electron emission yield was higher and the discharge voltage was lower for 12CaO·7Al2O3 than for existing cathode materials such as Ni, Mo or W; therefore, the energy consumption of the fluorescent lamps can be improved using 12CaO·7Al2O3 cathodes. Prototype glow-discharge lamps using 12CaO·7Al2O3 were constructed and exhibited reasonable durability. PMID:27877401

The Tethered Moon

NASA Technical Reports Server (NTRS)

Zahnle, K.; Lupu, R.; Dobrovolskis, A.

2014-01-01

Cosmic collisions between terrestrial planets resemble somewhat the life cycle of the phoenix: worlds collide, are consumed in flame, and after the debris has cleared, shiny new worlds emerge aglow with possibilities. And glow they do, for they are molten. How brightly they glow, and for how long, is determined by their atmospheres and their moons. A reasonable initial condition on Earth after the Moon-forming impact is that it begins as a hot global magma ocean. We therefore begin our study with the mantle as a liquid ocean with a surface temperature on the order of 3000-4000 K at a time some 100-1000 years after the impact, by which point we can hope that early transients have settled down.

Mechanism of altruism approach to blood donor recruitment and retention: a review and future directions.

PubMed

Ferguson, E

2015-08-01

Why do people donate blood? Altruism is the common answer. However, altruism is a complex construct and to answer this question requires a systematic analysis of the insights from the biology, economics and psychology of altruism. I term this the mechanism of altruism (MOA) approach and apply it here for understanding blood donor motivation. The answer also has enormous implications for the type of interventions we choose to adopt as a society. A MOA approach so far shows that blood donors are a mixture of (i) warm-glow givers (donation is emotionally rewarding) and (ii) reluctant altruists (cooperate rather than defect when free-riding is high). Donors also show 'saintly sinning' with the extra 'moral currency' form blood donation allowing them to be less generous in other contexts. The MOA approach suggests why financial incentives, in terms of gifts/lottery tickets, are effective and suggests a number of novel interventions for donor recruitment: 'voluntary reciprocal altruism' and 'charitable incentivisation'. The MOA approach also highlights the need for an intervention developed specifically for recipients to allow them to show their gratitude to donors and for society to celebrate blood donation. It is suggests a 'Monument to Blood Donors' will achieve this. The approach suggests a number of novel research questions into (i) donor self-selection effects, (ii) conditional cooperation and (iii) construct overlap with Theory of Planned Behaviour (e.g. affective attitudes and warm-glow). The MOA offers a powerful way to understand blood donor motivations around altruism and develop theoretically driven interventions. © 2015 British Blood Transfusion Society.

Excitation of nonlinear wave patterns in flowing complex plasmas

NASA Astrophysics Data System (ADS)

Jaiswal, S.; Bandyopadhyay, P.; Sen, A.

2018-01-01

We describe experimental observations of nonlinear wave structures excited by a supersonic mass flow of dust particles over an electrostatic potential hill in a dusty plasma medium. The experiments have been carried out in a Π- shaped experimental (DPEx) device in which micron sized Kaolin particles are embedded in a DC glow discharge Argon plasma. An equilibrium dust cloud is formed by maintaining the pumping speed and gas flow rate and the dust flow is induced either by suddenly reducing the height of a potential hill or by suddenly reducing the gas flow rate. For a supersonic flow of the dust fluid precursor solitons are seen to propagate in the upstream direction while wake structures propagate in the downstream direction. For flow speeds with a Mach number greater than 2 the dust particles flowing over the potential hill give rise to dispersive dust acoustic shock waves. The experimental results compare favorably with model theories based on forced K-dV and K-dV Burger's equations.

Fiber-Based Measurement of Bow-Shock Spectra for Reentry Flight Testing

NASA Technical Reports Server (NTRS)

Schott, Timothy D.; Herring, Gregory C.; Munk, Michelle M.; Grinstead, Jay H.; Prabbu, Dinesh K.

2010-01-01

We demonstrated a fiber-based approach for obtaining optical spectra of a glowing bow shock in a high-enthalpy air flow. The work was performed in a ground test with the NASA Ames Aerodynamic Heating Facility (AHF) that is used for atmospheric reentry simulation. The method uses a commercial fiber optic that is embedded in the nose of an ablating bluntbody model and provides a line-of-sight view in the streamwise direction - directly upstream into the hot post-shock gas flow. Both phenolic impregnated carbon ablator (PICA) and phenolic carbon (PhenCarb 28) materials were used as thermal protection systems. Results show that the fibers survive the intense heat and operate sufficiently well during the first several seconds of a typical AHF run (20 MJ/kg). This approach allowed the acquisition of optical spectra, enabling a Boltzmann-based electronic excitation temperature measurement from Cu atom impurities (averaged over a line-of-sight through the gas cap, with a 0.04 sec integration time).

Methodology for the investigation of ignition near hot surfaces in a high-pressure shock tube

NASA Astrophysics Data System (ADS)

Niegemann, P.; Fikri, M.; Wlokas, I.; Röder, M.; Schulz, C.

2018-05-01

Autoignition of fuel/air mixtures is a determining process in internal combustion engines. Ignition can start either homogeneously in the gas phase after compression or in the vicinity of hot surfaces. While ignition properties of commercial fuels are conventionally described by a single quantity (octane number), it is known that some fuels have a varying propensity to the two processes. We present a new experimental concept that generates well-controlled temperature inhomogeneities in the shock-heated gases of a high-pressure shock tube. A shock-heated reactive mixture is brought into contact with a heated silicon nitride ceramic glow plug. The glow-plug temperature can be set up to 1200 K, higher than the post-reflected-shock gas temperatures (650-1050 K). High-repetition-rate chemiluminescence imaging is used to localize the onset of ignition in the vicinity of the hot surface. In experiments with ethanol, the results show that in most cases under shock-heated conditions, the ignition begins inhomogeneously in the vicinity of the glow plug and is favored because of the high wall temperature. Additionally, the interaction of geometry, external heating, and gas-dynamic effects was investigated by numerical simulations of the shock wave in a non-reactive flow.

Thermoluminescence, ESR and x-ray diffraction studies of CaSO4 : Dy phosphor subjected to post preparation high temperature thermal treatment

NASA Astrophysics Data System (ADS)

Bakshi, A. K.; Patwe, S. J.; Bhide, M. K.; Sanyal, B.; Natarajan, V.; Tyagi, A. K.; Kher, R. K.

2008-01-01

Thermoluminescence (TL), electron spin resonance (ESR) and x ray diffraction studies of CaSO4 : Dy phosphor subjected to post preparation high temperature treatment were carried out. Analysis of the TL glow curve indicated that the dosimetric glow peak at 240 °C reduces, whereas the low temperature satellite peak increases with the increase in the annealing temperature in the range 650-1000 °C. The influence of the annealing atmosphere on the TL glow curve structure was also observed. Reduction of the photoluminescence intensity of the annealed phosphor indicated that the environment of Dy3+ ions might have undergone some change due to high temperature treatment. Reduction in the ESR signal intensity corresponding to O_{3}^{-} and SO_{3}^{-} radicals was observed initially with the increase in the annealing temperaure; subsequently their intensity increased with temperature. Signals due to the SO_{4}^{-} radical vanished, when the phosphor was annealed beyond 800 °C. A signal corresponding to SH2- radicals was also observed in the ESR spectra for samples subjected to annealing in the temperature regime 800-1000 °C. XRD of the in situ annealed phosphor showed a change in the unit cell parameters. An endothermic peak at 860 °C in the DTA spectrum was observed.

K3Na(SO4)2 : Eu nanoparticles for high dose of ionizing radiation

NASA Astrophysics Data System (ADS)

Sahare, P. D.; Ranjan, Ranju; Salah, Numan; Lochab, S. P.

2007-02-01

K3Na(SO4)2 : Eu nanocrystalline powder was synthesized by the chemical co-precipitation method. The x-ray diffraction pattern of the nanomaterials shows a hexagonal structure for its crystals having grain size of ~28 nm. Transmission electron microscopy revealed that the K3Na(SO4)2 : Eu nanoparticles are single crystals with almost a uniform shape and size. Thermoluminescence (TL) was taken after irradiating the samples at various exposures of γ-rays from a 60Co source. A prominent TL glow peak is observed at 423 K along with three small peaks/shoulders at around 382, 460 and 509 K. The observed TL sensitivity of the prepared nanocrystalline powder is around 4 times more than that of LiF : Mg,Ti (TLD-100) phosphor. The 423 K peak of the nanomaterial phosphor eventually shows a near linear response with exposures increasing up to very high values (as high as 70 kGy), where all the other TLD phosphors saturate. This property along with its other desired properties such as high sensitivity, relatively simple glow curve structure and low fading makes the nanocrystalline phosphor a suitable dosimeter to estimate low as well as high exposures of γ-rays. TL analysis using the glow curve deconvolution technique was also done for determining different trapping parameters.