Retrieval of Raindrop Size Distribution, Vertical Air Velocity and Water Vapor Attenuation Using Dual-Wavelength Doppler Radar Observations

NASA Technical Reports Server (NTRS)

Heymsfield, Gerald M.; Tian, Lin; Li, Lihua; Srivastava, C.

2005-01-01

Two techniques for retrieving the slope and intercept parameters of an assumed exponential raindrop size distribution (RSD), vertical air velocity, and attenuation by precipitation and water vapor in light stratiform rain using observations by airborne, nadir looking dual-wavelength (X-band, 3.2 cm and W-band, 3.2 mm) radars are presented. In both techniques, the slope parameter of the RSD and the vertical air velocity are retrieved using only the mean Doppler velocities at the two wavelengths. In the first method, the intercept of the RSD is estimated from the observed reflectivity at the longer wavelength assuming no attenuation at that wavelength. The attenuation of the shorter wavelength radiation by precipitation and water vapor are retrieved using the observed reflectivity at the shorter wavelength. In the second technique, it is assumed that the longer wavelength suffers attenuation only in the melting band. Then, assuming a distribution of water vapor, the melting band attenuation at both wavelengths and the rain attenuation at the shorter wavelength are retrieved. Results of the retrievals are discussed and several physically meaningful results are presented.

The study of lead vapor ionization in discharge with a hot cathode and efficiency of its deposition on the substrates applied for plasma separation method

NASA Astrophysics Data System (ADS)

Antonov, N. N.; Samokhin, A. A.; Zhabin, S. N.; Gavrikov, A. V.; Smirnov, V. P.

2016-11-01

Spent nuclear fuel plasma separation method approbation implies the use of model substances. Thus it is necessary to solve the problem of material conversion into a cold plasma flow, as well as the problem of deposition on collectors. For this purpose, we carried out a kinetic and hydrodynamic simulation of the discharge with hot cathode in the lead vapor (lead vapor was injected into the interelectrode gap). Dependencies of the ionization efficiency, electrostatic potential distribution, density distribution of ions and electrons in the discharge gap on the discharge current density and the model substance vapor concentration were obtained. The simulation results show that at discharge current density of about 3.5 A/cm2 and the lead vapor concentration of 2 × 1012 cm-3, the ionization efficiency is close to 60%. Experimental research of the discharge with a hot cathode in the lead vapor was carried out. We also carried out the research of the Pb condensation coefficients on various substrates. For experimental data analysis the numerical model based on Monte Carlo method was used. The research results show that deposition coefficients at medium temperatures of substrates near 70 °C do not drop lower than 75%.

Experimental verification of corrosive vapor deposition rate theory in high velocity burner rigs

NASA Technical Reports Server (NTRS)

Gokoglu, S. A.; Santoro, G. J.

1986-01-01

The ability to predict deposition rates is required to facilitate modelling of high temperature corrosion by fused salt condensates in turbine engines. A corrosive salt vapor deposition theory based on multicomponent chemically frozen boundary layers (CFBL) has been successfully verified by high velocity burner rig experiments. The experiments involved internally air-impingement cooled, both rotating full and stationary segmented cylindrical collectors located in the crossflow of sodium-seeded combustion gases. Excellent agreement is found between the CFBL theory an the experimental measurements for both the absolute amounts of Na2SO4 deposition rates and the behavior of deposition rate with respect to collector temperature, mass flowrate (velocity) and Na concentration.

Experimental verification of corrosive vapor deposition rate theory in high velocity burner rigs

NASA Technical Reports Server (NTRS)

Gokoglu, Suleyman A.; Santoro, Gilbert J.

1986-01-01

The ability to predict deposition rates is required to facilitate modelling of high temperature corrosion by fused salt condensates in turbine engines. A corrosive salt vapor deposition theory based on multicomponent chemically frozen boundary layers (CFBL) has been successfully verified by high velocity burner rig experiments. The experiments involved internally air-impingement cooled, both rotating full and stationary segmented cylindrical collectors located in the crossflow of sodium-seeded combustion gases. Excellent agreement is found between the CFBL theory and the experimental measurements for both the absolute amounts of Na2SO4 deposition rates and the behavior of deposition rate with respect to collector temperature, mass flowrate (velocity) and Na concentration.

Feasibility of Acoustic Doppler Velocity Meters for the Production of Discharge Records from U.S. Geological Survey Streamflow-Gaging Stations

USGS Publications Warehouse

Morlock, Scott E.; Nguyen, Hieu T.; Ross, Jerry H.

2002-01-01

It is feasible to use acoustic Doppler velocity meters (ADVM's) installed at U.S. Geological Survey (USGS) streamflow-gaging stations to compute records of river discharge. ADVM's are small acoustic current meters that use the Doppler principle to measure water velocities in a two-dimensional plane. Records of river discharge can be computed from stage and ADVM velocity data using the 'index velocity' method. The ADVM-measured velocities are used as an estimator or 'index' of the mean velocity in the channel. In evaluations of ADVM's for the computation of records of river discharge, the USGS installed ADVM's at three streamflow-gaging stations in Indiana: Kankakee River at Davis, Fall Creek at Millersville, and Iroquois River near Foresman. The ADVM evaluation study period was from June 1999 to February 2001. Discharge records were computed, using ADVM data from each station. Discharge records also were computed using conventional stage-discharge methods of the USGS. The records produced from ADVM and conventional methods were compared with discharge record hydrographs and statistics. Overall, the records compared closely from the Kankakee River and Fall Creek stations. For the Iroquois River station, variable backwater was present and affected the comparison; because the ADVM record compensates for backwater, the ADVM record may be superior to the conventional record. For the three stations, the ADVM records were judged to be of a quality acceptable to USGS standards for publications and near realtime ADVM-computed discharges are served on USGS real-time data World Wide Web pages.

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.

Surface charge dynamics and OH and H number density distributions in near-surface nanosecond pulse discharges at a liquid / vapor interface

NASA Astrophysics Data System (ADS)

Winters, Caroline; Petrishchev, Vitaly; Yin, Zhiyao; Lempert, Walter R.; Adamovich, Igor V.

2015-10-01

The present work provides insight into surface charge dynamics and kinetics of radical species reactions in nanosecond pulse discharges sustained at a liquid-vapor interface, above a distilled water surface. The near-surface plasma is sustained using two different discharge configurations, a surface ionization wave discharge between two exposed metal electrodes and a double dielectric barrier discharge. At low discharge pulse repetition rates (~100 Hz), residual surface charge deposition after the discharge pulse is a minor effect. At high pulse repetition rates (~10 kHz), significant negative surface charge accumulation over multiple discharge pulses is detected, both during alternating polarity and negative polarity pulse trains. Laser induced fluorescence (LIF) and two-photon absorption LIF (TALIF) line imaging are used for in situ measurements of spatial distributions of absolute OH and H atom number densities in near-surface, repetitive nanosecond pulse discharge plasmas. Both in a surface ionization wave discharge and in a double dielectric barrier discharge, peak measured H atom number density, [H] is much higher compared to peak OH number density, due to more rapid OH decay in the afterglow between the discharge pulses. Higher OH number density was measured near the regions with higher plasma emission intensity. Both OH and especially H atoms diffuse out of the surface ionization wave plasma volume, up to several mm from the liquid surface. Kinetic modeling calculations using a quasi-zero-dimensional H2O vapor / Ar plasma model are in qualitative agreement with the experimental data. The results demonstrate the experimental capability of in situ radical species number density distribution measurements in liquid-vapor interface plasmas, in a simple canonical geometry that lends itself to the validation of kinetic models.

Analytic non-Maxwellian electron velocity distribution function in a Hall discharge plasma

NASA Astrophysics Data System (ADS)

Shagayda, Andrey; Tarasov, Alexey

2017-10-01

The electron velocity distribution function in the low-pressure discharges with the crossed electric and magnetic fields, which occur in magnetrons, plasma accelerators, and Hall thrusters with a closed electron drift, is not Maxwellian. A deviation from equilibrium is caused by a large electron mean free path relative to the Larmor radius and the size of the discharge channel. In this study, we derived in the relaxation approximation the analytical expression of the electron velocity distribution function in a weakly ionized Lorentz plasma with the crossed electric and magnetic fields in the presence of the electron density and temperature gradients in the direction of the electric field. The solution was obtained in the stationary approximation far from boundary surfaces, when diffusion and mobility are determined by the classical effective collision frequency of electrons with ions and atoms. The moments of the distribution function including the average velocity, the stress tensor, and the heat flux were calculated and compared with the classical hydrodynamic expressions. It was shown that a kinetic correction to the drift velocity stems from a contribution of the off-diagonal component of the stress tensor. This correction becomes essential if the drift velocity in the crossed electric and magnetic fields would be comparable to the thermal velocity of electrons. The electron temperature has three different components at a nonzero effective collision frequency and two different components in the limit when the collision frequency tends to zero. It is shown that, in the presence of ionization collisions, the components of the heat flux have additives that are not related to the temperature gradient, and arise because of the electron drift.

A Self Consistent RF Discharge, Plasma Chemistry and Surface Model for Plasma Enhanced Chemical Vapor Deposition

DTIC Science & Technology

1988-06-30

consists of three submodels for the electron kinetics, plasma chemistry , and surface deposition kinetics for a-Si:H deposited from radio frequency...properties. Plasma enhanced, Chemical vapor deposition, amorphous silicon, Modeling, Electron kinetics, Plasma chemistry , Deposition kinetics, Rf discharge, Silane, Film properties, Silicon.

Monitoring of stage and velocity, for computation of discharge in the Summit Conduit near Summit, Illinois, 2010-2012

USGS Publications Warehouse

Johnson, Kevin K.; Goodwin, Greg E.

2013-01-01

Lake Michigan diversion accounting is the process used by the U. S. Army Corps of Engineers to quantify the amount of water that is diverted from the Lake Michigan watershed into the Illinois and Mississippi River Basins. A network of streamgages within the Chicago area waterway system monitor tributary river flows and the major river flow on the Chicago Sanitary and Ship Canal near Lemont as one of the instrumental tools used for Lake Michigan diversion accounting. The mean annual discharges recorded by these streamgages are used as additions or deductions to the mean annual discharge recorded by the main stream gaging station currently used in the Lake Michigan diversion accounting process, which is the Chicago Sanitary and Ship Canal near Lemont, Illinois (station number 05536890). A new stream gaging station, Summit Conduit near Summit, Illinois (station number 414757087490401), was installed on September 23, 2010, for the purpose of monitoring stage, velocity, and discharge through the Summit Conduit for the U.S. Army Corps of Engineers in accordance with Lake Michigan diversion accounting. Summit Conduit conveys flow from a small part of the lower Des Plaines River watershed underneath the Des Plaines River directly into the Chicago Sanitary and Ship Canal. Because the Summit Conduit discharges into the Chicago Sanitary and Ship Canal upstream from the stream gaging station at Lemont, Illinois, but does not contain flow diverted from the Lake Michigan watershed, it is considered a flow deduction to the discharge measured by the Lemont stream gaging station in the Lake Michigan diversion accounting process. This report offers a technical summary of the techniques and methods used for the collection and computation of the stage, velocity, and discharge data at the Summit Conduit near Summit, Illinois stream gaging station for the 2011 and 2012 Water Years. The stream gaging station Summit Conduit near Summit, Illinois (station number 414757087490401) is an

Multivariate regression methods for estimating velocity of ictal discharges from human microelectrode recordings

NASA Astrophysics Data System (ADS)

Liou, Jyun-you; Smith, Elliot H.; Bateman, Lisa M.; McKhann, Guy M., II; Goodman, Robert R.; Greger, Bradley; Davis, Tyler S.; Kellis, Spencer S.; House, Paul A.; Schevon, Catherine A.

2017-08-01

Objective. Epileptiform discharges, an electrophysiological hallmark of seizures, can propagate across cortical tissue in a manner similar to traveling waves. Recent work has focused attention on the origination and propagation patterns of these discharges, yielding important clues to their source location and mechanism of travel. However, systematic studies of methods for measuring propagation are lacking. Approach. We analyzed epileptiform discharges in microelectrode array recordings of human seizures. The array records multiunit activity and local field potentials at 400 micron spatial resolution, from a small cortical site free of obstructions. We evaluated several computationally efficient statistical methods for calculating traveling wave velocity, benchmarking them to analyses of associated neuronal burst firing. Main results. Over 90% of discharges met statistical criteria for propagation across the sampled cortical territory. Detection rate, direction and speed estimates derived from a multiunit estimator were compared to four field potential-based estimators: negative peak, maximum descent, high gamma power, and cross-correlation. Interestingly, the methods that were computationally simplest and most efficient (negative peak and maximal descent) offer non-inferior results in predicting neuronal traveling wave velocities compared to the other two, more complex methods. Moreover, the negative peak and maximal descent methods proved to be more robust against reduced spatial sampling challenges. Using least absolute deviation in place of least squares error minimized the impact of outliers, and reduced the discrepancies between local field potential-based and multiunit estimators. Significance. Our findings suggest that ictal epileptiform discharges typically take the form of exceptionally strong, rapidly traveling waves, with propagation detectable across millimeter distances. The sequential activation of neurons in space can be inferred from clinically

High strain rate metalworking with vaporizing foil actuator: Control of flyer velocity by varying input energy and foil thickness

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

Vivek, A., E-mail: vivek.4@osu.edu; Hansen, S. R.; Daehn, Glenn S.

2014-07-15

Electrically driven rapid vaporization of thin metallic foils can generate a high pressure which can be used to launch flyers at high velocities. Recently, vaporizing foil actuators have been applied toward a variety of impulse-based metal working operations. In order to exercise control over this useful tool, it is imperative that an understanding of the effect of characteristics of the foil actuator on its ability for mechanical impulse generation is developed. Here, foil actuators made out of 0.0508 mm, 0.0762 mm, and 0.127 mm thick AA1145 were used for launching AA2024-T3 sheets of thickness 0.508 mm toward a photonic Dopplermore » velocimeter probe. Launch velocities ranging between 300 m/s and 1100 m/s were observed. In situ measurement of velocity, current, and voltage assisted in understanding the effect of burst current density and deposited electrical energy on average pressure and velocity with foil actuators of various thicknesses. For the pulse generator, geometry, and flyer used here, the 0.0762 mm thick foil was found to be optimal for launching flyers to high velocities over short distances. Experimenting with annealed foil actuators resulted in no change in the temporal evolution of flyer velocity as compared to foil actuators of full hard temper. A physics-based analytical model was developed and found to have reasonable agreement with experiment.« less

Influence of ethanol vapor addition on the surface modification of polyethylene in a dielectric barrier discharge

NASA Astrophysics Data System (ADS)

Van Deynse, Annick; Morent, Rino; Leys, Christophe; De Geyter, Nathalie

2017-10-01

In this paper, ethanol vapor up to 50% is added to an argon, air or nitrogen dielectric barrier discharge at medium pressure to profoundly investigate the effect of ethanol addition on the surface modification of low density polyethylene (LDPE). Water contact angle (WCA) and X-ray photoelectron spectroscopy (XPS) measurements show that the ethanol vapor addition effect on the LDPE surface depends on the used carrier gas. Adding ethanol to an argon plasma has no significant effect on the wettability nor on the chemical composition of LDPE compared to a pure argon plasma treatment. Ethanol addition does however slightly increase the LDPE surface roughness. Addition of small amounts of ethanol vapor to an air plasma makes it possible to incorporate additional nitrogen and oxygen groups on the LDPE surface, resulting in an extra decrease of 11% in WCA value. Moreover, the LDPE surface roughness is slightly increased due to the ethanol vapor addition. The most significant effect of ethanol addition is however observed when nitrogen is used as carrier gas. After an N2/2% ethanol plasma treatment, an 85% reduction in WCA value to 8.5° is found compared to a pure N2 plasma treatment. This very hydrophilic LDPE surface is obtained due to a significantly high incorporation of oxygen and nitrogen groups on the surface with an O/C and N/C ratio reaching 32% and 53% respectively. FTIR measurements also reveal that the observed extremely high wettability of LDPE is not the result of plasma activation but is due to plasma polymerization effects occurring on the surface resulting into the deposition of a plasma polymer containing ketones, amides as well as Cdbnd N groups. In addition, ageing studies have also been conducted and these studies reveal that for all carrier gases, ethanol addition to the discharge gas significantly suppresses the ageing effect. All the above mentioned conclusions therefore indicate that ethanol vapor based plasmas can be an excellent tool to increase

Effect of gas velocity and influent concentration on biofiltration of gasoline off-gas from soil vapor extraction.

PubMed

Namkoong, Wan; Park, Joon-Seok; VanderGheynst, Jean S

2004-11-01

This study was conducted to evaluate the effects of gas inlet concentration and velocity on the biofiltration of gasoline vapor. Gasoline vapor was treated using a compost biofilter operated in an upflow mode for about 3 months. The inlet concentration of gasoline total petroleum hydrocarbon (TPH) ranged from about 300 to 7000 mgm(-3) and gas was injected at velocities of 6 and 15 mh(-1) (empty bed residence time (EBRT)=10 and 4 min, respectively). The maximum elimination capacities of TPH at 6 and 15 mh(-1) found in this research were over 24 and 19 gm(-3) of filling material h(-1), respectively. TPH removal data was fit using a first-order kinetic relationship. In the low concentration range of 300-3000 mg m(-3), the first-order kinetic constants varied between about 0.10 and 0.29 min(-1) regardless of gas velocities. At TPH concentrations greater than 3000 mgm(-3), the first-order kinetic constants were about 0.09 and 0.07 min(-1) at gas velocities of 6 mh(-1) and 15 mh(-1), respectively. To evaluate microbial dynamics, dehydrogenase activity, CO2 generation and microbial species diversity were analyzed. Dehydrogenase activity could be used as an indicator of microbial activity. TPH removal corresponded well with CO2 evolution. The average CO2 recovery efficiency for the entire biofilter ranged between 60% and 70%. When the gas velocity was 6 mh(-1), most of the microbial activity and TPH removal occurred in the first quarter of the biofilter. However, when the gas velocity was 15 mh(-1), the entire column contributed to removal. Spatial and temporal variations in the biofilter microbial population were also observed. Nearly 60% of the colonies isolated from the compost media prior to biofiltration were Bacillus. After 90 days of biofiltration, the predominant species in the lower portion (0-50 cm) of the filter were Rhodococcus, while Pseudomonas and Acinetobacter dominated the upper portion (75-100 cm). copyright 2004 Elsevier Ltd.

Mean flows and blob velocities in scrape-off layer (SOLT) simulations of an L-mode discharge on Alcator C-Mod

DOE PAGES

Russell, D. A.; Myra, J. R.; D'Ippolito, D. A.; ...

2016-06-10

Two-dimensional scrape-off layer turbulence (SOLT) code simulations are compared with an L-mode discharge on the Alcator C-Mod tokamak [M. Greenwald, et al., Phys. Plasmas 21, 110501 (2014)]. Density and temperature profiles for the simulations were obtained by smoothly fitting Thomson scattering and mirror Langmuir probe (MLP) data from the shot. Simulations differing in turbulence intensity were obtained by varying a dissipation parameter. Mean flow profiles and density fluctuation amplitudes are consistent with those measured by MLP in the experiment and with a Fourier space diagnostic designed to measure poloidal phase velocity. Blob velocities in the simulations were determined from themore » correlation function for density fluctuations, as in the analysis of gas-puff-imaging (GPI) blobs in the experiment. In the simulations, it was found that larger blobs moved poloidally with the ExB flow velocity, v E , in the near-SOL, while smaller fluctuations moved with the group velocity of the dominant linear (interchange) mode, v E + 1/2 v di, where v di is the ion diamagnetic drift velocity. Comparisons are made with the measured GPI correlation velocity for the discharge. The saturation mechanisms operative in the simulation of the discharge are also discussed. In conclusion, it is found that neither sheared flow nor pressure gradient modification can be excluded as saturation mechanisms.« less

On Both Spatial And Velocity Distribution Of Sputtered Particles In Magnetron Discharge

NASA Astrophysics Data System (ADS)

Vitelaru, C.; Pohoata, V.; Tiron, V.; Costin, C.; Popa, G.

2012-12-01

The kinetics of the sputtered atoms from the metallic target as well as the time-space distribution of the argon metastable atoms have been investigated for DC and high power pulse magnetron discharge by means of Tunable Diode - Laser Absorption Spectroscopy (TD-LAS) and Tunable Diode - Laser Induced Fluorescence (TD-LIF). The discharge was operated in argon (5-30 mTorr) with two different targets, tungsten and aluminum, for pulses of 1 to 20 μs, at frequencies of 0.2 to 1 kHz. Peak current intensity of ~100 A has been attained at cathode peak voltage of ~1 kV. The mean velocity distribution functions and particle fluxes of the sputtered metal atoms, in parallel and perpendicular direction to the target, have been obtained and compared for DC and pulse mode.

Large-capacity pump vaporizer for liquid hydrogen and nitrogen

NASA Technical Reports Server (NTRS)

Hauser, J. A.

1970-01-01

Pump vaporizer system delivers 500 standard cubic feet per minute of hydrogen or nitrogen, one system delivers both gases. Vacuum-jacketed pump discharges liquid hydrogen or liquid nitrogen into vaporizing system heated by ambient air. Principal characteristics of the flow and discharge system, pump, and vaporizer are given.

Optical characteristics and parameters of gas-discharge plasma in a mixture of mercury dibromide vapor with argon

NASA Astrophysics Data System (ADS)

Malinina, A. A.; Malinin, A. N.

2015-03-01

Results are presented from studies of the optical characteristics and parameters of the plasma of a dielectric barrier discharge in a mixture of mercury dibromide vapor with argon—the working medium of an exciplex gas-discharge emitter. It is established that the partial pressures of mercury dibromide vapor and argon at which the average and pulsed emission intensities in the blue—green spectral region (λmax = 502 nm) reach their maximum values are 0.6 and 114.4 kPa, respectively. The electron energy distribution function, the transport characteristics, the specific power spent on the processes involving electrons, the electron density and temperature, and the rate constants for the processes of elastic and inelastic electron scattering from the molecules and atoms of the working mixture are determined by numerical simulation, and their dependences on the reduced electric field strength are analyzed. The rate constant of the process leading to the formation of exciplex mercury monobromide molecules for a reduced electric field of E/ N = 20 Td, at which the maximum emission intensity in the blue—green spectral region was observed in this experiment, is found to be 8.1 × 10-15 m3/s.

Influence of Substrate Temperature on the Transformation Front Velocities That Determine Thermal Stability of Vapor-Deposited Glasses

DOE PAGES

Dalal, Shakeel S.; Ediger, M. D.

2015-02-09

Stable organic glasses prepared by physical vapor deposition transform into the supercooled liquid via propagating fronts of molecular mobility, a mechanism different from that exhibited by glasses prepared by cooling the liquid. In this paper, we show that spectroscopic ellipsometry can directly observe this front-based mechanism in real time and explore how the velocity of the front depends upon the substrate temperature during deposition. For the model glass former indomethacin, we detect surface-initiated mobility fronts in glasses formed at substrate temperatures between 0.68T g and 0.94T g. At each of two annealing temperatures, the substrate temperature during deposition can changemore » the transformation front velocity by a factor of 6, and these changes are imperfectly correlated with the density of the glass. We also observe substrate-initiated fronts at some substrate temperatures. By connecting with theoretical work, we are able to infer the relative mobilities of stable glasses prepared at different substrate temperatures. Finally, an understanding of the transformation behavior of vapor-deposited glasses may be relevant for extending the lifetime of organic semiconducting devices.« less

Design and physical features of inductive coaxial copper vapor lasers

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

Batenin, V. M.; Kazaryan, M. A.; Karpukhin, V. T.

A physical model of a copper vapor laser pumped by a pulse-periodic inductive (electrodeless) discharge is considered. The feasibility of efficient laser pumping by an inductive discharge and reaching high output parameters comparable to those of conventional copper vapor lasers pumped by a longitudinal electrode discharge is demonstrated. The design and physical features of an inductive copper vapor laser with an annular working volume are discussed.

Electrical Breakdown in Water Vapor

NASA Astrophysics Data System (ADS)

Škoro, N.; Marić, D.; Malović, G.; Graham, W. G.; Petrović, Z. Lj.

2011-11-01

In this paper investigations of the voltage required to break down water vapor are reported for the region around the Paschen minimum and to the left of it. In spite of numerous applications of discharges in biomedicine, and recent studies of discharges in water and vapor bubbles and discharges with liquid water electrodes, studies of the basic parameters of breakdown are lacking. Paschen curves have been measured by recording voltages and currents in the low-current Townsend regime and extrapolating them to zero current. The minimum electrical breakdown voltage for water vapor was found to be 480 V at a pressure times electrode distance (pd) value of around 0.6 Torr cm (˜0.8 Pa m). The present measurements are also interpreted using (and add additional insight into) the developing understanding of relevant atomic and particularly surface processes associated with electrical breakdown.

Dissipated power and induced velocity fields data of a micro single dielectric barrier discharge plasma actuator for active flow control☆

PubMed Central

Pescini, E.; Martínez, D.S.; De Giorgi, M.G.; Francioso, L.; Ficarella, A.

2015-01-01

In recent years, single dielectric barrier discharge (SDBD) plasma actuators have gained great interest among all the active flow control devices typically employed in aerospace and turbomachinery applications [1,2]. Compared with the macro SDBDs, the micro single dielectric barrier discharge (MSDBD) actuators showed a higher efficiency in conversion of input electrical power to delivered mechanical power [3,4]. This article provides data regarding the performances of a MSDBD plasma actuator [5,6]. The power dissipation values [5] and the experimental and numerical induced velocity fields [6] are provided. The present data support and enrich the research article entitled “Optimization of micro single dielectric barrier discharge plasma actuator models based on experimental velocity and body force fields” by Pescini et al. [6]. PMID:26425667

The Catalytic Effect of Electronegative Additives on Removal of Perchloroethylene Vapor from Air by Pulsed Corona Discharge

NASA Astrophysics Data System (ADS)

Filatov, I. E.; Uvarin, V. V.; Kuznetsov, D. L.

2017-12-01

It is established that electronegative additives (CCl4, freon-113) produce a catalytic effect on the conversion of volatile organic compounds (VOCs) under the action of atmospheric-pressure nonequilibrium plasma generated in pulsed corona discharge. At concentrations below 0.1%, these additives significantly decrease the discharge current, but the energy efficiency of the process of VOC removal from air increases. The catalytic effect of electronegative additives on the VOC conversion in air and nitrogen is quantitatively demonstrated in the case of perchloroethylene C2Cl4 (PCE) vapor removal. The addition of 0.085% CCl4 to air reduces the energy consumption for PCE removal at initial concentration of 0.09% by half (from 12 to 6 eV per molecule) at a 63% degree of cleaning. Mechanisms explaining the active inf luence of electronegative additives on the discharge current and the process of impurity removal are suggested.

The limiting velocity effect in a magnetically held discharge with a moving wall

NASA Astrophysics Data System (ADS)

Drobyshevskii, E. M.; Zhukov, B. G.; Nazarov, E. V.; Rozov, S. I.; Sokolov, V. M.; Kurakin, R. O.

1991-08-01

Experiments are reported in which bodies with a mass of about 1 g were accelerated in nearly constant current regimes by using a discharge magnetically held against the channel wall, with maximum permissible accelerations of 3.5 x 10 exp 6 g and linear current densities of 60 kA/mm. A saturation of the velocity was observed at 4-6 mm/microsec. The velocity limit does not depend on the current intensity and duration or linear electrode inductance and is proportional to m exp -1/2; it is practically unaffected by the characteristics of body friction against the channel walls and by small deviations of the current pulse shape from its constant value. A simple empirical theory is proposed which provides an adequate description of the experimentally observed phenomena.

Towards a Copernicus Service for Monitoring Polar Ice Sheet Velocity and Discharge using Sentinel-1A and 1B SAR

NASA Astrophysics Data System (ADS)

Wuite, Jan; Nagler, Thomas; Hetzenecker, Markus; Blumthaler, Ursula; Ossowska, Joanna; Rott, Helmut

2017-04-01

The enhanced imaging capabilities of Sentinel-1A and 1B and the systematic acquisition planning of polar regions by ESA form the basis for the development and implementation of an operational system for monitoring ice dynamics and discharge of Antarctica, Greenland and other polar ice caps. Within the framework of the ESA CCI and the Austrian ASAP/FFG programs we implemented an automatic system for generation of ice velocity maps from repeat pass Sentinel-1 Terrain Observation by Progressive Scans (TOPS) mode data applying iterative offset tracking using both coherent and incoherent image cross-correlation. Greenland's margins are monitored by 6 tracks continuously since mid of 2015 with 12 days repeat observations using Sentinel-1A. With the twin satellite Sentinel-1B, launched in April 2016, the repeat acquisition period is reduced to only 6 days allowing frequent velocity retrievals - even in regions with high accumulation rates and very fast flow - and providing insight for studying short-term variations of ice flow and discharge. The Sentinel-1 ice velocity products continue the sparse coverage in time and space of previous velocity mapping efforts. The annual Greenland wide winter acquisition campaigns of 4 to 6 repeat track observations, acquired within a few weeks, provide nearly gapless and seamless ice sheet wide flow velocity maps on a yearly basis which are important for ice sheet modelling purposes and accurate mass balance assessments. An Antarctic ice sheet wide ice velocity map (with polar gap) was generated from Sentinel-1A data, acquired within 8 months, providing an important benchmark for gauging future changes in ice dynamics. For regions with significant warming continuous monitoring of ice streams with 6 to 12-day repeat intervals, exploiting both satellites, is ongoing to detect changes of ice flow as indicators of climate change. We present annual ice sheet wide velocity maps of Greenland from 2014/15 to 2016/17 and Antarctica from 2015

Cryogenic spray vaporization in high-velocity helium, argon and nitrogen gasflows

NASA Technical Reports Server (NTRS)

Ingebo, Robert D.

1993-01-01

Effects of gas properties on cryogenic liquid-jet atomization in high-velocity helium, nitrogen, and argon gas flows were investigated. Volume median diameter, D(sub v.5e), data were obtained with a scattered-light scanning instrument. By calculating the change in spray drop size, -Delta D(sub v.5)(exp 2), due to droplet vaporization, it was possible to calculate D(sub v.5C). D(sub v.5C) is the unvaporized characteristic drop size formed at the fuel-nozzle orifice. This drop size was normalized with respect to liquid-jet diameter, D(sub O). It was then correlated with several dimensionless groups to give an expression for the volume median diameter of cryogenic LN2 sprays. This expression correlates drop size D(sub v.5c) with aerodynamic and liquid-surface forces so that it can be readily determined in the design of multiphase-flow propellant injectors for rocket combustors.

A prototype of radar-drone system for measuring the surface flow velocity at river sites and discharge estimation

NASA Astrophysics Data System (ADS)

Moramarco, Tommaso; Alimenti, Federico; Zucco, Graziano; Barbetta, Silvia; Tarpanelli, Angelica; Brocca, Luca; Mezzanotte, Paolo; Rosselli, Luca; Orecchini, Giulia; Virili, Marco; Valigi, Paolo; Ciarfuglia, Thomas; Pagnottelli, Stefano

2015-04-01

Discharge estimation at a river site depends on local hydraulic conditions identified by recording water levels. In fact, stage monitoring is straightforward and relatively inexpensive compared with the cost necessary to carry out flow velocity measurements which are, however, limited to low flows and constrained by the accessibility of the site. In this context the mean flow velocity is hard to estimate for high flow, affecting de-facto the reliability of discharge assessment for extreme events. On the other hand, the surface flow velocity can be easily monitored by using radar sensors allowing to achieve a good estimate of discharge by exploiting the entropy theory applied to rivers hydraulic (Chiu,1987). Recently, a growing interest towards the use of Unmanned Aerial Vehicle (UVA), henceforth drone, for topographic applications is observed and considering their capability drones may be of a considerable interest for the hydrological monitoring and in particular for streamflow measurements. With this aim, for the first time, a miniaturized Doppler radar sensor, operating at 24 GHz, will be mounted on a drone to measure the surface flow velocity in rivers. The sensor is constituted by a single-board circuit (i.e. is a fully planar circuits - no waveguides) with the antenna on one side and the front-end electronic on the other side (Alimenti et al., 2007). The antenna has a half-power beam width of less than 10 degrees in the elevation plane and a gain of 13 dBi. The radar is equipped with a monolithic oscillator and transmits a power of about 4 mW at 24 GHz. The sensor is mounted with an inclination of 45 degrees with respect to the drone flying plane and such an angle is considered in recovering the surface speed of the water. The drone is a quadricopter that has more than 30 min, flying time before recharging the battery. Furthermore its flying plan can be scheduled with a suitable software and is executed thanks to the on-board sensors (GPS, accelerometers

Chemical reaction between water vapor and stressed glass

NASA Technical Reports Server (NTRS)

Soga, N.; Okamoto, T.; Hanada, T.; Kunugi, M.

1979-01-01

The crack velocity in soda-lime silicate glass was determined at room temperature at water-vapor pressures of 10 to 0.04 torr using the double torsion technique. A precracked glass specimen (70 x 16 x 1.6 mm) was placed in a vacuum chamber containing a four-point bending test apparatus. The plotted experimental results show that the crack propagation curve in water agrees fairly well with that of Wiederhorn (1967). Attention is given to the effect of water vapor pressure on crack velocity at K(I) = 550,000 N/m to the 3/2 power, with (Wiederhorn's data) or without N2 present. The plotted results reveal that the present crack velocity is about two orders of magnitude higher than that of Wiederhorn at high water-vapor conditions, but the difference decreases as the water-vapor concentration diminishes or the crack velocity slows down.

Numerical study on the splitting of a vapor bubble in the ultrasonic assisted EDM process with the curved tool and workpiece.

PubMed

Shervani-Tabar, M T; Seyed-Sadjadi, M H; Shabgard, M R

2013-01-01

Electrical discharge machining (EDM) is a powerful and modern method of machining. In the EDM process, a vapor bubble is generated between the tool and the workpiece in the dielectric liquid due to an electrical discharge. In this process dynamic behavior of the vapor bubble affects machining process. Vibration of the tool surface affects bubble behavior and consequently affects material removal rate (MRR). In this paper, dynamic behavior of the vapor bubble in an ultrasonic assisted EDM process after the appearance of the necking phenomenon is investigated. It is noteworthy that necking phenomenon occurs when the bubble takes the shape of an hour-glass. After the appearance of the necking phenomenon, the vapor bubble splits into two parts and two liquid jets are developed on the boundaries of the upper and lower parts of the vapor bubble. The liquid jet developed on the upper part of the bubble impinges to the tool and the liquid jet developed on the lower part of the bubble impinges to the workpiece. These liquid jets cause evacuation of debris from the gap between the tool and the workpiece and also cause erosion of the workpiece and the tool. Curved tool and workpiece affect the shape and the velocity of the liquid jets during splitting of the vapor bubble. In this paper dynamics of the vapor bubble after its splitting near the curved tool and workpiece is investigated in three cases. In the first case surfaces of the tool and the workpiece are flat, in the second case surfaces of the tool and the workpiece are convex and in the third case surfaces of the tool and workpiece are concave. Numerical results show that in the third case, the velocity of liquid jets which are developed on the boundaries of the upper and lower parts of the vapor bubble after its splitting have the highest magnitude and their shape are broader than the other cases. Copyright © 2012 Elsevier B.V. All rights reserved.

Optical Characteristics of a Gas Discharge Plasma Based on a Mixture of Mercury Diiodide Vapor, Nitrogen, and Helium

NASA Astrophysics Data System (ADS)

Malinina, A. A.; Malinin, A. N.

2016-09-01

The results of studies of spectral, temporal, and energy characteristics of radiation in a gas discharge plasma based on a mixture of mercury diiodide vapor with helium and nitrogen in the spectral range of 350-800 nm are presented. Plasma was produced by a barrier discharge in a device with a cylindrical aperture. The electrodes 0.2 m in length were placed at a distance of 0.015 m. The amplitude of the pump pulses, their duration, and frequency were equal to 20-30 kV, 150 ns, and 1-20 kHz, respectively. Radiation of mercury monoiodide exciplex molecules was revealed in the visible spectra region. Dependences of the plasma optical characteristics on the partial pressures of the mixture components were established.

Remote determination of the velocity index and mean streamwise velocity profiles

NASA Astrophysics Data System (ADS)

Johnson, E. D.; Cowen, E. A.

2017-09-01

When determining volumetric discharge from surface measurements of currents in a river or open channel, the velocity index is typically used to convert surface velocities to depth-averaged velocities. The velocity index is given by, k=Ub/Usurf, where Ub is the depth-averaged velocity and Usurf is the local surface velocity. The USGS (United States Geological Survey) standard value for this coefficient, k = 0.85, was determined from a series of laboratory experiments and has been widely used in the field and in laboratory measurements of volumetric discharge despite evidence that the velocity index is site-specific. Numerous studies have documented that the velocity index varies with Reynolds number, flow depth, and relative bed roughness and with the presence of secondary flows. A remote method of determining depth-averaged velocity and hence the velocity index is developed here. The technique leverages the findings of Johnson and Cowen (2017) and permits remote determination of the velocity power-law exponent thereby, enabling remote prediction of the vertical structure of the mean streamwise velocity, the depth-averaged velocity, and the velocity index.

Influence of temperature on the ionization coefficient and ignition voltage of the Townsend discharge in an argon-mercury vapor mixture

NASA Astrophysics Data System (ADS)

Bondarenko, G. G.; Fisher, M. R.; Kristya, V. I.

2017-02-01

The kinetics of main types of charged and excited particles present in a low-current discharge in an argon-mercury vapor mixture used in gas-discharge illuminating lamps has been investigated in a wide interval of the reduced electric field strength and temperature. Mechanisms behind the production and loss of ions and metastable atoms have been discovered, and the temperature dependences of their contributions to maintaining their balance have been determined. It has been shown that, when the discharge is initiated in the lamp and the mercury content in the mixture is low, the ionization coefficient exceeds that in pure argon, which is almost exclusively due to the Penning reaction. The influence of this reaction grows with a reduction of the electric field strength in the interelectrode gap. The dependences of the discharge ignition voltage on the interelectrode gap (Paschen curves) for different temperatures of the mixture have been calculated, and the nonmonotonicity of the temperature dependence of the ignition voltage has been explained.

Optical characteristics and parameters of gas-discharge plasma in a mixture of mercury dibromide vapor with neon

NASA Astrophysics Data System (ADS)

Malinina, A. A.; Malinin, A. N.

2013-12-01

Results are presented from studies of the optical characteristics and parameters of plasma of a dielectric barrier discharge in a mixture of mercury dibromide vapor with neon—the working medium of a non-coaxial exciplex gas-discharge emitter. The electron energy distribution function, the transport characteristics, the specific power losses for electron processes, the electron density and temperature, and the rate constants for the processes of elastic and inelastic electron scattering by the working mixture components are determined as functions of the reduced electric field. The rate constant of the process leading to the formation of exciplex mercury monobromide molecules is found to be 1.6 × 10-14 m3/s for a reduced electric field of E/ N = 15 Td, at which the maximum emission intensity in the blue-green spectral region (λmax = 502 nm) was observed in this experiment.

Impact Vaporization of Planetesimal Cores

NASA Astrophysics Data System (ADS)

Kraus, R. G.; Root, S.; Lemke, R. W.; Stewart, S. T.; Jacobsen, S. B.; Mattsson, T. R.

2013-12-01

The degree of mixing and chemical equilibration between the iron cores of planetesimals and the mantle of the growing Earth has important consequences for understanding the end stages of Earth's formation and planet formation in general. At the Sandia Z machine, we developed a new shock-and-release technique to determine the density on the liquid-vapor dome of iron, the entropy on the iron shock Hugoniot, and the criteria for shock-induced vaporization of iron. We find that the critical shock pressure to vaporize iron is 507(+65,-85) GPa and show that decompression from a 15 km/s impact will initiate vaporization of iron cores, which is a velocity that is readily achieved at the end stages of planet formation. Vaporization of the iron cores increases dispersal of planetesimal cores, enables more complete chemical equilibration of the planetesimal cores with Earth's mantle, and reduces the highly siderophile element abundance on the Moon relative to Earth due to the expanding iron vapor exceeding the Moon's escape velocity. Sandia National Laboratories is a multiprogram laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Securities Administration under Contract No. DE-AC04-94AL85000.

Boiler for generating high quality vapor

NASA Technical Reports Server (NTRS)

Gray, V. H.; Marto, P. J.; Joslyn, A. W.

1972-01-01

Boiler supplies vapor for use in turbines by imparting a high angular velocity to the liquid annulus in heated rotating drum. Drum boiler provides a sharp interface between boiling liquid and vapor, thereby, inhibiting the formation of unwanted liquid droplets.

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.

The Vapor-phase Multi-stage CMD Test for Characterizing Contaminant Mass Discharge Associated with VOC Sources in the Vadose Zone: Application to Three Sites in Different Lifecycle Stages of SVE Operations

PubMed Central

Brusseau, M.L.; Mainhagu, J.; Morrison, C.; Carroll, K.C.

2015-01-01

Vapor-phase multi-stage contaminant mass discharge (CMD) tests were conducted at three field sites to measure mass discharge associated with contaminant sources located in the vadose zone. The three sites represent the three primary stages along the soil vapor extraction (SVE) operations lifecycle- pre/initial-SVE, mid-lifecycle, and near-closure. A CMD of 32 g/d was obtained for a site at which soil vapor SVE has been in operation for approximately 6 years, and for which mass removal is currently in the asymptotic stage. The contaminant removal behavior exhibited for the vapor extractions conducted at this site suggests that there is unlikely to be a significant mass of non-vapor-phase contaminant (e.g., DNAPL, sorbed phase) remaining in the advective domains, and that most remaining mass is likely located in poorly accessible domains. Given the conditions for this site, this remaining mass is hypothesized to be associated with the low-permeability (and higher water saturation) region in the vicinity of the saturated zone and capillary fringe. A CMD of 25 g/d was obtained for a site wherein SVE has been in operation for several years but concentrations and mass-removal rates are still relatively high. A CMD of 270 g/d was obtained for a site for which there were no prior SVE operations. The behavior exhibited for the vapor extractions conducted at this site suggest that non-vapor-phase contaminant mass (e.g., DNAPL) may be present in the advective domains. Hence, the asymptotic conditions observed for this site most likely derive from a combination of rate-limited mass transfer from DNAPL (and sorbed) phases present in the advective domain as well as mass residing in lower-permeability (“non-advective”) regions. The CMD values obtained from the tests were used in conjunction with a recently developed vapor-discharge tool to evaluate the impact of the measured CMDs on groundwater quality. PMID:26047819

The vapor-phase multi-stage CMD test for characterizing contaminant mass discharge associated with VOC sources in the vadose zone: Application to three sites in different lifecycle stages of SVE operations.

PubMed

Brusseau, M L; Mainhagu, J; Morrison, C; Carroll, K C

2015-08-01

Vapor-phase multi-stage contaminant mass discharge (CMD) tests were conducted at three field sites to measure mass discharge associated with contaminant sources located in the vadose zone. The three sites represent the three primary stages of the soil vapor extraction (SVE) operations lifecycle-pre/initial-SVE, mid-lifecycle, and near-closure. A CMD of 32g/d was obtained for a site at which soil vapor SVE has been in operation for approximately 6years, and for which mass removal is currently in the asymptotic stage. The contaminant removal behavior exhibited for the vapor extractions conducted at this site suggests that there is unlikely to be a significant mass of non-vapor-phase contaminant (e.g., DNAPL, sorbed phase) remaining in the advective domains, and that most remaining mass is likely located in poorly accessible domains. Given the conditions for this site, this remaining mass is hypothesized to be associated with the low-permeability (and higher water saturation) region in the vicinity of the saturated zone and capillary fringe. A CMD of 25g/d was obtained for a site wherein SVE has been in operation for several years but concentrations and mass-removal rates are still relatively high. A CMD of 270g/d was obtained for a site for which there were no prior SVE operations. The behavior exhibited for the vapor extractions conducted at this site suggest that non-vapor-phase contaminant mass (e.g., DNAPL) may be present in the advective domains. Hence, the asymptotic conditions observed for this site most likely derive from a combination of rate-limited mass transfer from DNAPL (and sorbed) phases present in the advective domain as well as mass residing in lower-permeability ("non-advective") regions. The CMD values obtained from the tests were used in conjunction with a recently developed vapor-discharge tool to evaluate the impact of the measured CMDs on groundwater quality. Copyright © 2015 Elsevier B.V. All rights reserved.

Sterilization of Long Tube Inner Surface Using Oxygen and Water Vapor Plasmas Produced by AC HV Discharge

NASA Astrophysics Data System (ADS)

Kitazaki, Satoshi; Hayashi, Nobuya

2009-10-01

Oxygen and water vapor plasmas inside a narrow long tube were produced using an AC HV glow discharge at low pressure in order to sterilize the inner surface of a tube. In order to produce plasma inside a narrow tube, an AC high voltage was adopted. The material of the tube used in this experiment was silicon rubber. The length and diameter of the tubes ranged from 300 to 1,000 mm and from 1 to 4 mm, respectively. The tube was placed in a stainless steel vacuum chamber and was evacuated to 10 Pa using a rotary pump. The material gas for plasma and radical productions was pure oxygen or water vapor, which was introduced to the chamber from a gas cylinder or water reservoir. Light emission spectral lines of oxygen and OH radicals were observed at 777 nm and 306 nm, respectively. The chemical indicator was inserted into the tube and turned to a yellowish color (from the original red) after a treatment, which indicates the generation of sufficient oxygen on OH radicals for sterilization. A tube with the length of 500 mm and diameter of 4 mm is sterilized using oxygen plasma by 10 minutes treatment. Also a tube with the length of 300 mm and diameter of 2 mm is sterilized using water vapor plasma by 5 minutes treatment.

Investigation of airflow effects on the dielectric barrier discharge with single/double discharge channel arrangement

NASA Astrophysics Data System (ADS)

Fan, Zhihui; Yan, Huijie; Liu, Yidi; Guo, Hongfei; Wang, Yuying; Ren, Chunsheng

2018-05-01

Atmospheric-pressure dielectric barrier discharge (DBD) with airflow participation has been widely used in recent years. In this paper, effects of airflow on DBD characteristics are experimentally investigated by single/double pin-to-plate DBD arrangements with an AC exciting source. The discharge electrical characteristics and the movements of discharge channels in airflow are investigated with a single pin electrode arrangement. The current intensities increase in positive cycles and decrease in negative cycles with the increase in airflow velocity. The transition from a filamentary discharge to a diffuse discharge is observed under certain airflow conditions, and the discharge channels move with the airflow with a movement velocity less than the corresponding airflow velocity. In the cases of double pin electrode arrangements, the repulsion between double pin discharge channels is apparent at a 10 mm distance but is not obvious at a 20 mm distance. When the airflow is introduced into the discharge gap, not as in the case of single pin electrode arrangement, the movements of discharge channels in airflow are affected by adjacent discharge channels. The corresponding reasons are analyzed in the paper.

Determination of trace cadmium in rice by liquid spray dielectric barrier discharge induced plasma - chemical vapor generation coupled with atomic fluorescence spectrometry

NASA Astrophysics Data System (ADS)

Liu, Xing; Zhu, Zhenli; Bao, Zhengyu; Zheng, Hongtao; Hu, Shenghong

2018-03-01

Cadmium contamination in rice has become an increasing concern in many countries including China. A simple, cost-effective, and highly sensitive method was developed for the determination of trace cadmium in rice samples based on a new high-efficient liquid spray dielectric barrier discharge induced plasma (LSDBD) vapor generation coupled with atomic fluorescence spectrometry (AFS). The analytical procedure involves the efficient formation of Cd volatile species by LSDBD plasma induced chemical processes without the use of any reducing reagents (Na/KBH4 in conventional hydride generation). The effects of the addition of organic substances, different discharge parameters such as discharge voltage and discharge gap, as well as the foreign ion interferences were investigated. Under optimized conditions, a detection limit of 0.01 μg L- 1 and a precision of 0.8% (RSD, n = 5, 1 μg L- 1 Cd) was readily achieved. The calibration curve was linear in the range between 0.1 and 10 μg L- 1, with a correlation coefficient of R2 = 0.9995. Compared with the conventional acid-BH4- vapor generation, the proposed method not only eliminates the use of unstable and expensive reagents, but also offers high tolerance for coexisting ions, which is well suited to the direct analysis of environmental samples. The validation of the proposed method was demonstrated by the analysis of Cd in reference material of rice (GBW080684). It was also successfully applied to the determination of trace cadmium in locally collected 11 rice samples, and the obtained Cd concentrations are ranged from 7.2 to 517.7 μg kg- 1.

GAS DISCHARGE DEVICES

DOEpatents

Jefferson, S.

1958-11-11

An apparatus utilized in introducing tritium gas into envelope of a gas discharge device for the purpose f maintaining the discharge path in ionized condition is described. ln addition to the cathode and anode, the ischarge device contains a zirconium or tantalum ilament arranged for external excitation and a metallic seed containing tritium, and also arranged to have a current passed through it. Initially, the zirconium or tantalum filament is vaporized to deposit its material adjacent the main discharge region. Then the tritium gas is released and, due to its affinity for the first released material, it deposits in the region of the main discharge where it is most effective in maintaining the discharge path in an ionized condition.

Shock wave induced vaporization of porous solids

NASA Astrophysics Data System (ADS)

Shen, Andy H.; Ahrens, Thomas J.; O'Keefe, John D.

2003-05-01

Strong shock waves generated by hypervelocity impact can induce vaporization in solid materials. To pursue knowledge of the chemical species in the shock-induced vapors, one needs to design experiments that will drive the system to such thermodynamic states that sufficient vapor can be generated for investigation. It is common to use porous media to reach high entropy, vaporized states in impact experiments. We extended calculations by Ahrens [J. Appl. Phys. 43, 2443 (1972)] and Ahrens and O'Keefe [The Moon 4, 214 (1972)] to higher distentions (up to five) and improved their method with a different impedance match calculation scheme and augmented their model with recent thermodynamic and Hugoniot data of metals, minerals, and polymers. Although we reconfirmed the competing effects reported in the previous studies: (1) increase of entropy production and (2) decrease of impedance match, when impacting materials with increasing distentions, our calculations did not exhibit optimal entropy-generating distention. For different materials, very different impact velocities are needed to initiate vaporization. For aluminum at distention (m)<2.2, a minimum impact velocity of 2.7 km/s is required using tungsten projectile. For ionic solids such as NaCl at distention <2.2, 2.5 km/s is needed. For carbonate and sulfate minerals, the minimum impact velocities are much lower, ranging from less than 1 to 1.5 km/s.

Performance Measurements and Mapping of a R-407C Vapor Injection Scroll Compressor

NASA Astrophysics Data System (ADS)

Lumpkin, Domenique; Spielbauer, Niklas; Groll, Eckhard

2017-08-01

Environmental conditions significantly define the performance of HVAC&R systems. Vapor compression systems in hot climates tend to operate at higher pressure ratios, leading to increased discharge temperatures. Higher discharge temperatures can lead to higher irreversibilities in the compression process, lower specific enthalpies differences across the evaporator, and possibly a reduction in the compressor life due to the breakdown of the oil used for lubrication. To counter these effects, the use of economized, vapor injection compressors is proposed for vapor compression systems in high temperature climates. Such compressors are commercially available for refrigeration applications, in particular, supermarket refrigeration systems. However, compressor maps for vapor injection compressors are limited and none exist for R-407C. Through calorimeter testing, a compressor map for a single-port vapor injection compressor using R-407C was developed. A standard correlation for mapping single-port vapor injection compressors is proposed and validated using the compressor test results. The system and compressor performance with and without vapor injection was considered. As expected, with vapor injection there was a reduction in compressor discharge temperatures and an increase in the system coefficient of performance. The proposed dimensionless correlation is more accurate than the AHRI polynomial for mapping the injection ratio, discharge temperature, and compressor heat loss. The predicted volumetric efficiency values from the dimensionless correlation is within 1% of the measured valued. Similarly, the predicted isentropic efficiency values are within 2% of the measured values.

33 CFR 157.132 - Cargo tanks: Hydrocarbon vapor emissions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Cargo tanks: Hydrocarbon vapor... § 157.132 Cargo tanks: Hydrocarbon vapor emissions. Each tank vessel having a COW system under § 157.10a... must have— (a) A means to discharge hydrocarbon vapors from each cargo tank that is ballasted to a...

Methods for accurate estimation of net discharge in a tidal channel

USGS Publications Warehouse

Simpson, M.R.; Bland, R.

2000-01-01

Accurate estimates of net residual discharge in tidally affected rivers and estuaries are possible because of recently developed ultrasonic discharge measurement techniques. Previous discharge estimates using conventional mechanical current meters and methods based on stage/discharge relations or water slope measurements often yielded errors that were as great as or greater than the computed residual discharge. Ultrasonic measurement methods consist of: 1) the use of ultrasonic instruments for the measurement of a representative 'index' velocity used for in situ estimation of mean water velocity and 2) the use of the acoustic Doppler current discharge measurement system to calibrate the index velocity measurement data. Methods used to calibrate (rate) the index velocity to the channel velocity measured using the Acoustic Doppler Current Profiler are the most critical factors affecting the accuracy of net discharge estimation. The index velocity first must be related to mean channel velocity and then used to calculate instantaneous channel discharge. Finally, discharge is low-pass filtered to remove the effects of the tides. An ultrasonic velocity meter discharge-measurement site in a tidally affected region of the Sacramento-San Joaquin Rivers was used to study the accuracy of the index velocity calibration procedure. Calibration data consisting of ultrasonic velocity meter index velocity and concurrent acoustic Doppler discharge measurement data were collected during three time periods. Two sets of data were collected during a spring tide (monthly maximum tidal current) and one of data collected during a neap tide (monthly minimum tidal current). The relative magnitude of instrumental errors, acoustic Doppler discharge measurement errors, and calibration errors were evaluated. Calibration error was found to be the most significant source of error in estimating net discharge. Using a comprehensive calibration method, net discharge estimates developed from the three

Heavy component of spent nuclear fuel: Efficiency of model-substance ionization by electron-induced discharge

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

Antonov, N. N., E-mail: antonovnickola@gmail.com; Gavrikov, A. V.; Samokhin, A. A.

The method of plasma separation of spent nuclear fuel can be tested with a model substance which has to be transformed from the condensed to plasma state. For this purpose, electron-induced discharge in lead vapor injected into the interelectrode gap is simulated using the kinetic approach. The ionization efficiency, the electrostatic-potential distribution, and those of the ion and electron densities in the discharge gap are derived as functions of the discharge-current density and concentration of the vapor of the model substance. Given a discharge-current density of 3.5 A/cm{sup 2} and a lead-vapor concentration of 2 × 10{sup 12} cm{sup –3},more » the simulated ionization efficiency proves to be nearly 60%. The discharge in lead vapor is also investigated experimentally.« less

Note: implementation of a cold spot setup for controlled variation of vapor pressures and its application to an InBr containing discharge lamp.

PubMed

Briefi, S

2013-02-01

In order to allow for a systematic investigation of the plasma properties of discharges containing indium halides, which are proposed as an efficient alternative for mercury based low pressure discharge lamps, a controlled variation of the indium halide density is mandatory. This can be achieved by applying a newly designed setup in which a well-defined cold spot location is implemented and the cold spot temperature can be adjusted between 50 and 350 °C without influencing the gas temperature. The performance of the setup has been proved by comparing the calculated evaporated InBr density (using the vapor pressure curve) with the one measured via white light absorption spectroscopy.

Vapor Pressure Deficit and Sap Velocity Dynamic Coupling in Canopy Dominant Trees in the Amazon basin

NASA Astrophysics Data System (ADS)

Chambers, J. Q.; Gimenez, B.; Jardine, K.; Negron Juarez, R. I.; Cobello, L. O.; Fontes, C.; Dawson, T. E.; Higuchi, N.

2017-12-01

In order to improve our ability to predict terrestrial water fluxes, an understanding of the interactions between plant physiology and environmental conditions is necessary, especially in tropical forests which recycle large fluxes of water to the atmosphere. This need has become more relevant due to observed records in global temperature. In this study we show a strong temporal correlation between sap velocity and leaf-to-air vapor pressure deficit (VPD) in canopy dominant trees in two primary rainforest sites in the Amazon basin (Santarém and Manaus, Brazil). As VPDs in the upper canopy (20-30 m) varied throughout the day and night, basal sap velocity (1.5 m) responded rapidly without an observable delay (< 15 min). Sap velocity showed a sigmoidal dependence on VPDs including an exponential increase, an inflection point, and a plateau, in all observed trees. Moreover, a clear diurnal hysteresis in sap velocity, stomatal conductance, and leaf water potential was evident with morning periods showing higher sensitivities to VPD than afternoon and night periods. Diurnal leaf gas exchange observations revealed a morning to midday peak in stomatal conductance, but midday to afternoon peak in transpiration and VPD. Thus, our study confirms that the temporal lag between the Gs peak and VPD peak are the major regulators of the hysteresis phenomenon as previously described by other studies. Moreover, out study provide direct evidence for the role of decreased stomatal conductance in the warm afternoon periods to reduce transpiration and allow for the partial recovery of leaf water potential to less negative values. Our results suggests the possibility of predicting evapotranspiration fluxes from ecosystem to regional scales using remote sensing of vegetation temperature from, for example, thermal images of satellites and drones.

Vaporizing particle velocimeter

NASA Technical Reports Server (NTRS)

Weinstein, Leonard M. (Inventor)

1992-01-01

A velocimeter measures flow characteristics of a flow traveling through a chamber in a given direction. Tracer particles are entrained in the flow and a source of radiant energy produces an output stream directed transversely to the chamber, having a sufficient intensity to vaporize the particles as they pass through the output stream. Each of the vaporized particles explodes to produce a shock wave and a hot core, and a flow visualization system tracks the motion of the hot cores and shock waves to measure the velocity of each tracer particle and the temperature of the flow around the tracer.

Solvent vapor collector

DOEpatents

Ellison, Kenneth; Whike, Alan S.

1979-01-30

A solvent vapor collector is mounted on the upstream inlet end of an oven having a gas-circulating means and intended for curing a coating applied to a strip sheet metal at a coating station. The strip sheet metal may be hot and solvent vapors are evaporated at the coating station and from the strip as it passes from the coating station to the oven. Upper and lower plenums within a housing of the collector are supplied with oven gases or air from the gas-circulating means and such gases or air are discharged within the collector obliquely in a downstream direction against the strip passing through that collector to establish downstream gas flows along the top and under surfaces of the strip so as, in turn, to induct solvent vapors into the collector at the coating station. A telescopic multi-piece shroud is usefully provided on the housing for movement between an extended position in which it overlies the coating station to collect solvent vapors released thereat and a retracted position permitting ready cleaning and adjustment of that coating station.

Model for the Vaporization of Mixed Organometallic Compounds in the Metalorganic Chemical Vapor Deposition of High Temperature Superconducting Films

NASA Technical Reports Server (NTRS)

Meng, Guangyao; Zhou, Gang; Schneider, Roger L.; Sarma, Bimal K.; Levy, Moises

1993-01-01

A model of the vaporization and mass transport of mixed organometallics from a single source for thin film metalorganic chemical vapor deposition is presented. A stoichiometric gas phase can be obtained from a mixture of the organometallics in the desired mole ratios, in spite of differences in the volatilities of the individual compounds. Proper film composition and growth rates are obtained by controlling the velocity of a carriage containing the organometallics through the heating zone of a vaporizer.

Modeling the Dynamics of Micro- and Macroparticles in a Combined Gas-Discharge Installation

NASA Astrophysics Data System (ADS)

Astashinskii, V. V.; Bogach, M. I.; Burachevskii, A. V.

2016-05-01

We present a model of the dynamics of micro- and macroparticles in a combined gas-discharge installation that accounts for the processes of metal explosion (heating of a metal in its solid state, melting, heating of the liquid metal, intense evaporation, ionization in metal vapor), a magnetohydrodynamic description of plasma acceleration (on the basis of the mass, momentum, and energy conservation laws neglecting the plasma viscosity and thermal conductivity), and a description of the processes of energy transfer from a high-velocity stream to accelerated particles. It has been established that the process of melting terminates in 1.3 ns after the start of the discharge and that the evaporation terminates in 480 ns. The stage of cooling starts in 21 μs. The average density of the plasma upon completion of the evaporation process can be estimated to be 1.7·10-5 g/cm3, with the pressure being of the order of 1.5·104 Pa and the total time of discharge, of about 250 μs.

A Planar-Fluorescence Imaging Technique for Studying Droplet-Turbulence Interactions in Vaporizing Sprays

NASA Technical Reports Server (NTRS)

Santavicca, Dom A.; Coy, E.

1990-01-01

Droplet turbulence interactions directly affect the vaporization and dispersion of droplets in liquid sprays and therefore play a major role in fuel oxidizer mixing in liquid fueled combustion systems. Proper characterization of droplet turbulence interactions in vaporizing sprays require measurement of droplet size velocity and size temperature correlations. A planar, fluorescence imaging technique is described which is being developed for simultaneously measuring the size, velocity, and temperature of individual droplets in vaporizing sprays. Preliminary droplet size velocity correlation measurements made with this technique are presented. These measurements are also compared to and show very good agreement with measurements made in the same spray using a phase Doppler particle analyzer.

Control of flow through a vapor generator

DOEpatents

Radcliff, Thomas D.

2005-11-08

In a Rankine cycle system wherein a vapor generator receives heat from exhaust gases, provision is made to avoid overheating of the refrigerant during ORC system shut down while at the same time preventing condensation of those gases within the vapor generator when its temperature drops below a threshold temperature by diverting the flow of hot gases to ambient and to thereby draw ambient air through the vapor generator in the process. In one embodiment, a bistable ejector is adjustable between one position, in which the hot gases flow through the vapor generator, to another position wherein the gases are diverted away from the vapor generator. Another embodiment provides for a fixed valve ejector with a bias towards discharging to ambient, but with a fan on the downstream side of said vapor generator for overcoming this bias.

Kinetic processes determining attainable pulse repetition rate in pulsed metal vapor lasers

NASA Astrophysics Data System (ADS)

Petrash, Gueorgii G.

1998-06-01

A review of the investigations of the main processes determining the attainable pulse repetition rate of elemental metal vapor pulsed gas discharge self-terminating lasers, such as copper vapor laser, gold vapor laser, lead vapor laser, is given. Kinetic processes during an excitation pulse and interpulse period are considered as well as experiments with lasers operating at high repetition rate.

Metal vapor laser including hot electrodes and integral wick

DOEpatents

Ault, Earl R.; Alger, Terry W.

1995-01-01

A metal vapor laser, specifically one utilizing copper vapor, is disclosed herein. This laser utilizes a plasma tube assembly including a thermally insulated plasma tube containing a specific metal, e.g., copper, and a buffer gas therein. The laser also utilizes means including hot electrodes located at opposite ends of the plasma tube for electrically exciting the metal vapor and heating its interior to a sufficiently high temperature to cause the metal contained therein to vaporize and for subjecting the vapor to an electrical discharge excitation in order to lase. The laser also utilizes external wicking arrangements, that is, wicking arrangements located outside the plasma tube.

Metal vapor laser including hot electrodes and integral wick

DOEpatents

Ault, E.R.; Alger, T.W.

1995-03-07

A metal vapor laser, specifically one utilizing copper vapor, is disclosed herein. This laser utilizes a plasma tube assembly including a thermally insulated plasma tube containing a specific metal, e.g., copper, and a buffer gas therein. The laser also utilizes means including hot electrodes located at opposite ends of the plasma tube for electrically exciting the metal vapor and heating its interior to a sufficiently high temperature to cause the metal contained therein to vaporize and for subjecting the vapor to an electrical discharge excitation in order to lase. The laser also utilizes external wicking arrangements, that is, wicking arrangements located outside the plasma tube. 5 figs.

Effects of Glen Canyon Dam discharges on water velocity and temperatures at the confluence of the Colorado and Little Colorado Rivers and implications for habitat for young-of-year humpback chub (Gila cypha-

USGS Publications Warehouse

Protiva, Frank R.; Ralston, Barbara E.; Stone, Dennis M.; Kohl, Keith A.; Yard, Michael D.; Haden, G. Allen

2010-01-01

Water velocity and temperature are physical variables that affect the growth and survivorship of young-of-year (YOY) fishes. The Little Colorado River, a tributary to the Colorado River in Grand Canyon, is an important spawning ground and warmwater refuge for the endangered humpback chub (Gila cypha) from the colder mainstem Colorado River that is regulated by Glen Canyon Dam. The confluence area of the Little Colorado River and the Colorado River is a site where YOY humpback chub (size 30-90 mm) emerging from the Little Colorado River experience both colder temperatures and higher velocities associated with higher mainstem discharge. We used detailed surveying and mapping techniques in combination with YOY velocity and temperature preferenda (determined from field and lab studies) to compare the areal extent of available habitat for young fishes at the confluence area under four mainstem discharges (227, 368, 504, and 878 m3/s). Comparisons revealed that the areal extent of low-velocity, warm water at the confluence decreased when discharges exceeded 368 m3/s. Furthermore, mainstem fluctuations, depending on the rate of upramp, can affect velocity and temperature dynamics in the confluence area within several hours. The amount of daily fluctuations in discharge can result in the loss of approximately 1.8 hectares of habitat favorable to YOY humpback chub. Consequently, flow fluctuations and the accompanying changes in velocity and temperature at the confluence may diminish the recruitment potential of humpback chub that spawn in the tributary stream. This study illustrates the utility of multiple georeferenced data sources to provide critical information related to the influence of the timing and magnitude of discharge from Glen Canyon Dam on potential rearing environment at the confluence area of the Little Colorado River.

Gunshot residue particle velocity and deceleration.

PubMed

De Forest, Peter R; Martir, Kirby; Pizzola, Peter A

2004-11-01

The velocity of over 800 gunshot residue particles from eight different sources was determined using high speed stroboscopic photography (spark gap light source). These particles were found to have an average velocity of 500 to 600 ft per second. Many particles acquired considerably higher velocities. Thus, the particles have sufficient energy to embed themselves within certain nearby targets like skin or fabric. The relatively high velocity that the particles acquire explain the formation of stippling on skin in close proximity to a muzzle discharge. These findings also indicate little influence of air currents on particle behavior near the muzzle. The deceleration of less than 100 particles during a 100-microsecond interval was also calculated. The particles experienced rapid rates of deceleration which would explain why few particles are found in test firings beyond 3 ft from the muzzle of a discharged firearm. Because of their relatively high velocity, normal wind velocity would not be expected to significantly influence their motion near the muzzle.

Water Vapor Effects on Silica-Forming Ceramics

NASA Technical Reports Server (NTRS)

Opila, E. J.; Greenbauer-Seng, L. (Technical Monitor)

2000-01-01

Silica-forming ceramics such as SiC and Si3N4 are proposed for applications in combustion environments. These environments contain water vapor as a product of combustion. Oxidation of silica-formers is more rapid in water vapor than in oxygen. Parabolic oxidation rates increase with the water vapor partial pressure with a power law exponent value close to one. Molecular water vapor is therefore the mobile species in silica. Rapid oxidation rates and large amounts of gases generated during the oxidation reaction in high water vapor pressures may result in bubble formation in the silica and nonprotective scale formation. It is also shown that silica reacts with water vapor to form Si(OH)4(g). Silica volatility has been modeled using a laminar flow boundary layer controlled reaction equation. Silica volatility depends on the partial pressure of water vapor, the total pressure, and the gas velocity. Simultaneous oxidation and volatilization reactions have been modeled with paralinear kinetics.

Investigating Vaporization of Silica through Laser Driven Shock Wave Experiments

NASA Astrophysics Data System (ADS)

Kraus, R. G.; Swift, D. C.; Stewart, S. T.; Smith, R.; Bolme, C. A.; Spaulding, D. K.; Hicks, D.; Eggert, J.; Collins, G.

2010-12-01

Giant impacts melt and vaporize a significant amount of the bolide and target body. However, our ability to determine how much melt or vapor a given impact creates depends strongly on our understanding of the liquid-vapor phase boundary of geologic materials. Our current knowledge of the liquid-vapor equilibrium for one of the most important minerals, SiO2, is rather limited due to the difficulty of performing experiments in this area of phase space. In this study, we investigate the liquid-vapor coexistence region by shocking quartz into a supercritical fluid state and allowing it to adiabatically expand to a state on the liquid-vapor phase boundary. Although shock compression and release has been used to study the liquid-vapor equilibrium of metals [1], few attempts have been made at studying geologic materials by this method [2]. Shock waves were produced by direct ablation of the quartz sample using the Jupiter Laser Facility of Lawrence Livermore National Laboratory. Steady shock pressures of 120-360 GPa were produced in the quartz samples: high enough to force the quartz into a supercritical fluid state. As the shock wave propagates through the sample, we measure the shock velocity using a line imaging velocity interferometer system for any reflector (VISAR) and shock temperature using a streaked optical pyrometer (SOP). When the shock wave reaches the free surface of the sample, the material adiabatically expands. Upon breakout of the shock at the free surface, the SOP records a distinct drop in radiance due to the lower temperature of the expanded material. For a subset of experiments, a LiF window is positioned downrange of the expanding silica. When the expanding silica impacts the LiF window, the velocity at the interface between the expanding silica and LiF window is measured using the VISAR. From the shock velocity measurements, we accurately determine the shocked state in the quartz. The post-shock radiance measurements are used to constrain the

Comparison, analysis, and estimation of discharge data from two acoustic velocity meters on the Chicago Sanitary and Ship Canal at Romeoville, Illinois

USGS Publications Warehouse

Melching, Charles S.; Oberg, Kevin A.

1993-01-01

The acoustic velocity meter (AVM) on the Chicago Sanitary and Ship Canal (the Canal) at Romeoville, Ill., provides vital information for the accounting of the diversion of water from Lake Michigan. A detailed analysis of the discharge record on the Canal at Romeoville was done by the U.S. Geological Survey to establish the most accurate estimates of discharge for water years 1986-91. The analysis involved (1) checking the consistency of the discharges estimated by two different AVM's installed at Romeoville for consecutive time periods by statistical and regression analyses, (2) adjusting the discharge record to account for corrections to the width and depth of the Canal determined by field measurements, and (3) development of equations for estimating discharge on days when the AVM was inoperative using discharge estimates made by the Metropolitan Water Reclamation District of Greater Chicago at the lock, powerhouse, and controlling works at Lockport, Ill. No signi- ficant difference in the discharge estimates made by the two AVM's could be documented. The estimation equations combined regression analysis with physical principles of the outlet-works operation. The estimation equations simulated the verification period of October 1, 1991, to May 31, 1992, within 0.22, 5.15, and 0.66 percent for the mean, standard deviation, and skewness coefficient, respectively. Discharges were recalculated for the corrected width and depth, estimated for the periods of AVM inoperation, and entered into the discharge record for the station.

Experimental verification of the vaporization's contribution to the shock waves generated by underwater electrical wire explosion under micro-second timescale pulsed discharge

NASA Astrophysics Data System (ADS)

Han, Ruoyu; Zhou, Haibin; Wu, Jiawei; Clayson, Thomas; Ren, Hang; Wu, Jian; Zhang, Yongmin; Qiu, Aici

2017-06-01

This paper studies pressure waves generated by exploding a copper wire in a water medium, demonstrating the significant contribution of the vaporization process to the formation of shock waves. A test platform including a pulsed current source, wire load, chamber, and diagnostic system was developed to study the shock wave and optical emission characteristics during the explosion process. In the experiment, a total of 500 J was discharged through a copper wire load 0.2 mm in diameter and 4 cm in length. A water gap was installed adjacent to the load so that the current was diverted away from the load after breakdown occurred across the water gap. This allows the electrical energy injection into the load to be interrupted at different times and at different stages of the wire explosion process. Experimental results indicate that when the load was bypassed before the beginning of the vaporization phase, the measured peak pressure was less than 2.5 MPa. By contrast, the peak pressure increased significantly to over 6.5 MPa when the water gap broke down after the beginning of the vaporization phase. It was also found that when bypassing the load after the voltage peak, similar shock waves were produced to those from a non-bypassed load. However, the total optical emission of these bypassed loads was at least an order of magnitude smaller. These results clearly demonstrate that the vaporization process is vital to the formation of shock waves and the energy deposited after the voltage collapse may only have a limited effect.

Iron bromide vapor laser

NASA Astrophysics Data System (ADS)

Sukhanov, V. B.; Shiyanov, D. V.; Trigub, M. V.; Dimaki, V. A.; Evtushenko, G. S.

2016-03-01

We have studied the characteristics of a pulsed gas-discharge laser on iron bromide vapor generating radiation with a wavelength of 452.9 nm at a pulse repetition frequency (PRF) of 5-30 kHz. The maximum output power amounted to 10 mW at a PRF within 5-15 kHz for a voltage of 20-25 kV applied to electrodes of the discharge tube. Addition of HBr to the medium produced leveling of the radial profile of emission. Initial weak lasing at a wavelength of 868.9 nm was observed for the first time, which ceased with buildup of the main 452.9-nm line.

Using advanced oxidation treatment for biofilm inactivation by varying water vapor content in air plasma

NASA Astrophysics Data System (ADS)

Ryota, Suganuma; Koichi, Yasuoka

2015-09-01

Biofilms are caused by environmental degradation in food factories and medical facilities. The inactivation of biofilms involves making them react with chemicals including chlorine, hydrogen peroxide, and ozone, although inactivation using chemicals has a potential problem because of the hazardous properties of the residual substance and hydrogen peroxide, which have slow reaction velocity. We successfully performed an advanced oxidation process (AOP) using air plasma. Hydrogen peroxide and ozone, which were used for the formation of OH radicals in our experiment, were generated by varying the amount of water vapor supplied to the plasma. By varying the content of the water included in the air, the main product was changed from air plasma. When we increased the water content in the air, hydrogen peroxide was produced, while ozone peroxide was produced when we decreased the water content in the air. By varying the amount of water vapor, we realized a 99.9% reduction in the amount of bacteria in the biofilm when we discharged humidified air only. This work was supported by JSPS KAKENHI Grant Number 25630104.

OH radicals generated by DC corona discharge for improving the pulsed discharge desulfuration efficiency.

PubMed

Li, Jie; Li, Guo-feng; Wu, Yan; Wang, Ning-hui; Huang, Qiu-nan

2004-01-01

Positive DC corona discharge is formed with needle-plate electrode configuration, in which the water vapor is ejected though the needle points. The purpose is to increase the numbers of the water-based radicals, ionize the water molecule and improve the desulfuration efficiency of pulsed corona reactor. The water ions were determined by four stages molecular beam mass spectrometer and diagnose the water-based radicals by emission spectrograph. A conclusion on formation of ions and radicals with DC corona discharges can be drawn.

Estimating discharge measurement uncertainty using the interpolated variance estimator

USGS Publications Warehouse

Cohn, T.; Kiang, J.; Mason, R.

2012-01-01

Methods for quantifying the uncertainty in discharge measurements typically identify various sources of uncertainty and then estimate the uncertainty from each of these sources by applying the results of empirical or laboratory studies. If actual measurement conditions are not consistent with those encountered in the empirical or laboratory studies, these methods may give poor estimates of discharge uncertainty. This paper presents an alternative method for estimating discharge measurement uncertainty that uses statistical techniques and at-site observations. This Interpolated Variance Estimator (IVE) estimates uncertainty based on the data collected during the streamflow measurement and therefore reflects the conditions encountered at the site. The IVE has the additional advantage of capturing all sources of random uncertainty in the velocity and depth measurements. It can be applied to velocity-area discharge measurements that use a velocity meter to measure point velocities at multiple vertical sections in a channel cross section.

Mass Spectrometry Vapor Analysis for Improving Explosives Detection Canine Proficiency

DTIC Science & Technology

2017-02-10

ionization (SESI), 8,19-21 dielectric barrier discharge ionization (DBDI), 21,22 selected-ion-flow-tube (SIFT), 23,24 and proton transfer reaction...handled only with wood- en or Teflon® spatulas to prevent static discharge . Using these precautions, we never experienced an accidental detonation...ionization (SESI) and dielectric barrier discharge ionization (DBDI) sources were used for vapor ioni- zation. Source temperature was held at 100 o C

Numerical studies of the effects of jet-induced mixing on liquid-vapor interface condensation

NASA Technical Reports Server (NTRS)

Lin, Chin-Shun

1989-01-01

Numerical solutions of jet-induced mixing in a partially full cryogenic tank are presented. An axisymmetric laminar jet is discharged from the central part of the tank bottom toward the liquid-vapor interface. Liquid is withdrawn at the same volume flow rate from the outer part of the tank. The jet is at a temperature lower than the interface, which is maintained at a certain saturation temperature. The interface is assumed to be flat and shear-free and the condensation-induced velocity is assumed to be negligibly small compared with radial interface velocity. Finite-difference method is used to solve the nondimensional form of steady state continuity, momentum, and energy equations. Calculations are conducted for jet Reynolds numbers ranging from 150 to 600 and Prandtl numbers ranging from 0.85 to 2.65. The effects of above stated parameters on the condensation Nusselt and Stanton numbers which characterize the steady-state interface condensation process are investigated. Detailed analysis to gain a better understanding of the fundamentals of fluid mixing and interface condensation is performed.

Transverse-type laser assembly using induced electrical discharge excitation and method

DOEpatents

Ault, Earl R.

1994-01-01

A transverse-type laser assembly is disclosed herein. This assembly defines a laser cavity containing a vapor or gaseous substance which lases when subjected to specific electrical discharge excitation between a pair of spaced-apart electrodes located within the cavity in order to produce a source of light. An arrangement located entirely outside the laser cavity is provided for inducing a voltage across the electrodes within the cavity sufficient to provide the necessary electrical discharge excitation to cause a vapor substance between the electrodes to lase.

Measuring stream discharge by non-contact methods: A proof-of-concept experiment

USGS Publications Warehouse

Costa, J.E.; Spicer, K.R.; Cheng, R.T.; Haeni, F.P.; Melcher, N.B.; Thurman, E.M.; Plant, W.J.; Keller, W.C.

2000-01-01

This report describes an experiment to make a completely non-contact open-channel discharge measurement. A van-mounted, pulsed doppler (10GHz) radar collected surface-velocity data across the 183-m wide Skagit River, Washington at a USGS streamgaging station using Bragg scattering from short waves produced by turbulent boils on the surface of the river. Surface velocities were converted to mean velocities for 25 sub-sections by assuming a normal open-channel velocity profile (surface velocity times 0.85). Channel cross-sectional area was measured using a 100 MHz ground-penetrating radar antenna suspended from a cableway car over the river. Seven acoustic doppler current profiler discharge measurements and a conventional current-meter discharge measurement were also made. Three non-contact discharge measurements completed in about a 1-hour period were within 1 % of the gaging station rating curve discharge values. With further refinements, it is thought that open-channel flow can be measured reliably by non-contact methods.

Experimental Investigation of the Induced Airflow of Corona Discharge

NASA Astrophysics Data System (ADS)

Huang, Yong; Zhang, Xin; Wang, Xun-Nian; Wang, Wan-Bo; Huang, Zong-Bo; Li, Hua-Xing

2013-09-01

In order to improve the acceleration effect of corona discharge acting on air, we present an experimental study on the induced airflow produced by corona discharge between two parallel electrodes. The parameters investigated are the type of electrodes, actuation voltage and the distance in the absence of free airflow. The induced flow velocity is measured directly in the accelerated region using the particle image velocimetry technology. The results show that if corona discharge is not developed into arc discharge, the induced airflow velocity increases nearly linearly with the applied voltage and the maximum induced airflow velocity near the needle electrode reaches 36 m/s. It is expected that in the future, the result can be referred to in the research about effect of active flow control to reach much higher induced airflow speed.

Studies of oscillatory combustion and fuel vaporization

NASA Technical Reports Server (NTRS)

Borman, G. L.; Myers, P. S.; Uyehara, O. A.

1972-01-01

Research projects involving oscillatory combustion and fuel vaporization are reported. Comparisons of experimental and theoretical droplet vaporization histories under ambient conditions such that the droplet may approach its thermodynamic critical point are presented. Experimental data on instantaneous heat transfer from a gas to a solid surface under conditions of oscillatory pressure with comparisons to an unsteady one-dimensional model are analyzed. Droplet size and velocity distribution in a spray as obtained by use of a double flash fluorescent method were investigated.

Transverse-type laser assembly using induced electrical discharge excitation and method

DOEpatents

Ault, E.R.

1994-04-19

A transverse-type laser assembly is disclosed herein. This assembly defines a laser cavity containing a vapor or gaseous substance which lases when subjected to specific electrical discharge excitation between a pair of spaced-apart electrodes located within the cavity in order to produce a source of light. An arrangement located entirely outside the laser cavity is provided for inducing a voltage across the electrodes within the cavity sufficient to provide the necessary electrical discharge excitation to cause a vapor substance between the electrodes to lase. 3 figures.

Relationship between cloud-to-ground discharge and penetrative clouds: A multi-channel satellite application

NASA Astrophysics Data System (ADS)

Machado, Luiz A. T.; Lima, Wagner F. A.; Pinto, Osmar; Morales, Carlos A.

This work presents a relationship between atmospheric cloud-to-ground discharges and penetrative convective clouds. It combines Infrared and Water Vapor channels from the GOES-12 geostationary satellite with cloud-to-ground discharge data from the Brazilian Integrated Lightning Detection Network (RINDAT) during the period from January to February 2005. The difference between water vapor and infrared brightness temperature is a tracer penetrating clouds. Due to the water vapor channel's strong absorption, this difference is positive only during overshooting cases, when convective clouds penetrate the stratosphere. From this difference and the cloud-to-ground, discharge measured on the ground by RINDAT, it was possible to adjust exponential curves that relate the brightness temperature difference from these two channels to the probability of occurrence of cloud-to-ground discharges, with a very large coefficient of determination. If WV-IR brightness temperature difference is greater than - 15 K there is a large potential for cloud-to-ground discharge activity. As this difference increases the cloud-to-ground discharge probably increases, for example: if this difference is equal to zero, the probability of having at least one cloud-to-ground discharge is 10.9%, 7.0% for two, 4.4% for four, 2.7% for eight and 1.5% for sixteen cloud-to-ground discharges. Through this process, was developed a scheme that estimates the probability of occurrence of cloud-to-ground discharge over all the continental region of South America.

Optical monitor for water vapor concentration

DOEpatents

Kebabian, Paul

1998-01-01

A system for measuring and monitoring water vapor concentration in a sample uses as a light source an argon discharge lamp, which inherently emits light with a spectral line that is close to a water vapor absorption line. In a preferred embodiment, the argon line is split by a magnetic field parallel to the direction of light propagation from the lamp into sets of components of downshifted and upshifted frequencies of approximately 1575 Gauss. The downshifted components are centered on a water vapor absorption line and are thus readily absorbed by water vapor in the sample; the upshifted components are moved away from that absorption line and are minimally absorbed. A polarization modulator alternately selects the upshifted components or downshifted components and passes the selected components to the sample. After transmission through the sample, the transmitted intensity of a component of the argon line varies as a result of absorption by the water vapor. The system then determines the concentration of water vapor in the sample based on differences in the transmitted intensity between the two sets of components. In alternative embodiments alternate selection of sets of components is achieved by selectively reversing the polarity of the magnetic field or by selectively supplying the magnetic field to the emitting plasma.

Optical monitor for water vapor concentration

DOEpatents

Kebabian, P.

1998-06-02

A system for measuring and monitoring water vapor concentration in a sample uses as a light source an argon discharge lamp, which inherently emits light with a spectral line that is close to a water vapor absorption line. In a preferred embodiment, the argon line is split by a magnetic field parallel to the direction of light propagation from the lamp into sets of components of downshifted and upshifted frequencies of approximately 1575 Gauss. The downshifted components are centered on a water vapor absorption line and are thus readily absorbed by water vapor in the sample; the upshifted components are moved away from that absorption line and are minimally absorbed. A polarization modulator alternately selects the upshifted components or downshifted components and passes the selected components to the sample. After transmission through the sample, the transmitted intensity of a component of the argon line varies as a result of absorption by the water vapor. The system then determines the concentration of water vapor in the sample based on differences in the transmitted intensity between the two sets of components. In alternative embodiments alternate selection of sets of components is achieved by selectively reversing the polarity of the magnetic field or by selectively supplying the magnetic field to the emitting plasma. 5 figs.

Modeling of inhomogeneous mixing of plasma species in argon-steam arc discharge

NASA Astrophysics Data System (ADS)

Jeništa, J.; Takana, H.; Uehara, S.; Nishiyama, H.; Bartlová, M.; Aubrecht, V.; Murphy, A. B.

2018-01-01

This paper presents numerical simulation of mixing of argon- and water-plasma species in an argon-steam arc discharge generated in a thermal plasma generator with the combined stabilization of arc by axial gas flow (argon) and water vortex. The diffusion of plasma species itself is described by the combined diffusion coefficients method in which the coefficients describe the diffusion of argon ‘gas,’ with respect to water vapor ‘gas.’ Diffusion processes due to the gradients of mass density, temperature, pressure, and an electric field have been considered in the model. Calculations for currents 150-400 A with 15-22.5 standard liters per minute (slm) of argon reveal inhomogeneous mixing of argon and oxygen-hydrogen species with the argon species prevailing near the arc axis. All the combined diffusion coefficients exhibit highly nonlinear distribution of their values within the discharge, depending on the temperature, pressure, and argon mass fraction of the plasma. The argon diffusion mass flux is driven mainly by the concentration and temperature space gradients. Diffusions due to pressure gradients and due to the electric field are of about 1 order lower. Comparison with our former calculations based on the homogeneous mixing assumption shows differences in temperature, enthalpy, radiation losses, arc efficiency, and velocity at 400 A. Comparison with available experiments exhibits very good qualitative and quantitative agreement for the radial temperature and velocity profiles 2 mm downstream of the exit nozzle.

Nonequilibrium kinetic boundary condition at the vapor-liquid interface of argon

NASA Astrophysics Data System (ADS)

Ishiyama, Tatsuya; Fujikawa, Shigeo; Kurz, Thomas; Lauterborn, Werner

2013-10-01

A boundary condition for the Boltzmann equation (kinetic boundary condition, KBC) at the vapor-liquid interface of argon is constructed with the help of molecular dynamics (MD) simulations. The KBC is examined at a constant liquid temperature of 85 K in a wide range of nonequilibrium states of vapor. The present investigation is an extension of a previous one by Ishiyama, Yano, and Fujikawa [Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.95.084504 95, 084504 (2005)] and provides a more complete form of the KBC. The present KBC includes a thermal accommodation coefficient in addition to evaporation and condensation coefficients, and these coefficients are determined in MD simulations uniquely. The thermal accommodation coefficient shows an anisotropic behavior at the interface for molecular velocities normal versus tangential to the interface. It is also found that the evaporation and condensation coefficients are almost constant in a fairly wide range of nonequilibrium states. The thermal accommodation coefficient of the normal velocity component is almost unity, while that of the tangential component shows a decreasing function of the density of vapor incident on the interface, indicating that the tangential velocity distribution of molecules leaving the interface into the vapor phase may deviate from the tangential parts of the Maxwell velocity distribution at the liquid temperature. A mechanism for the deviation of the KBC from the isotropic Maxwell KBC at the liquid temperature is discussed in terms of anisotropic energy relaxation at the interface. The liquid-temperature dependence of the present KBC is also discussed.

An improved algorithm for the modeling of vapor flow in heat pipes

NASA Technical Reports Server (NTRS)

Tower, Leonard K.; Hainley, Donald C.

1989-01-01

A heat pipe vapor flow algorithm suitable for use in codes on microcomputers is presented. The incompressible heat pipe vapor flow studies of Busse are extended to incorporate compressibility effects. The Busse velocity profile factor is treated as a function of temperature and pressure. The assumption of a uniform saturated vapor temperature determined by the local pressure at each cross section of the pipe is not made. Instead, a mean vapor temperature, defined by an energy integral, is determined in the course of the solution in addition to the pressure, saturation temperature at the wall, and the Busse velocity profile factor. For alkali metal working fluids, local species equilibrium is assumed. Temperature and pressure profiles are presented for several cases involving sodium heat pipes. An example for a heat pipe with an adiabatic section and two evaporators in sequence illustrates the ability to handle axially varying heat input. A sonic limit plot for a short evaporator falls between curves for the Busse and Levy inviscid sonic limits.

An improved algorithm for the modeling of vapor flow in heat pipes

NASA Astrophysics Data System (ADS)

Tower, Leonard K.; Hainley, Donald C.

1989-12-01

A heat pipe vapor flow algorithm suitable for use in codes on microcomputers is presented. The incompressible heat pipe vapor flow studies of Busse are extended to incorporate compressibility effects. The Busse velocity profile factor is treated as a function of temperature and pressure. The assumption of a uniform saturated vapor temperature determined by the local pressure at each cross section of the pipe is not made. Instead, a mean vapor temperature, defined by an energy integral, is determined in the course of the solution in addition to the pressure, saturation temperature at the wall, and the Busse velocity profile factor. For alkali metal working fluids, local species equilibrium is assumed. Temperature and pressure profiles are presented for several cases involving sodium heat pipes. An example for a heat pipe with an adiabatic section and two evaporators in sequence illustrates the ability to handle axially varying heat input. A sonic limit plot for a short evaporator falls between curves for the Busse and Levy inviscid sonic limits.

A technique for measuring hypersonic flow velocity profiles

NASA Technical Reports Server (NTRS)

Gartrell, L. R.

1973-01-01

A technique for measuring hypersonic flow velocity profiles is described. This technique utilizes an arc-discharge-electron-beam system to produce a luminous disturbance in the flow. The time of flight of this disturbance was measured. Experimental tests were conducted in the Langley pilot model expansion tube. The measured velocities were of the order of 6000 m/sec over a free-stream density range from 0.000196 to 0.00186 kg/cu m. The fractional error in the velocity measurements was less than 5 percent. Long arc discharge columns (0.356 m) were generated under hypersonic flow conditions in the expansion-tube modified to operate as an expansion tunnel.

Field assessment of noncontact stream gauging using portable surface velocity radars (SVR)

NASA Astrophysics Data System (ADS)

Welber, Matilde; Le Coz, Jérôme; Laronne, Jonathan B.; Zolezzi, Guido; Zamler, Daniel; Dramais, Guillaume; Hauet, Alexandre; Salvaro, Martino

2016-02-01

The applicability of a portable, commercially available surface velocity radar (SVR) for noncontact stream gauging was evaluated through a series of field-scale experiments carried out in a variety of sites and deployment conditions. Comparisons with various concurrent techniques showed acceptable agreement with velocity profiles, with larger uncertainties close to the banks. In addition to discharge error sources shared with intrusive velocity-area techniques, SVR discharge estimates are affected by flood-induced changes in the bed profile and by the selection of a depth-averaged to surface velocity ratio, or velocity coefficient (α). Cross-sectional averaged velocity coefficients showed smaller fluctuations and closer agreement with theoretical values than those computed on individual verticals, especially in channels with high relative roughness. Our findings confirm that α = 0.85 is a valid default value, with a preferred site-specific calibration to avoid underestimation of discharge in very smooth channels (relative roughness ˜ 0.001) and overestimation in very rough channels (relative roughness > 0.05). Theoretically derived and site-calibrated values of α also give accurate SVR-based discharge estimates (within 10%) for low and intermediate roughness flows (relative roughness 0.001 to 0.05). Moreover, discharge uncertainty does not exceed 10% even for a limited number of SVR positions along the cross section (particularly advantageous to gauge unsteady flood flows and very large floods), thereby extending the range of validity of rating curves.

Discharge dynamics of pin-to-plate dielectric barrier discharge at atmospheric pressure

NASA Astrophysics Data System (ADS)

Sun, Liqun; Huang, Xiaojiang; Zhang, Jie; Zhang, Jing; Shi, J. J.

2010-11-01

The discharge dynamics of pin-to-plate dielectric barrier discharge was studied in atmospheric helium at 20 kHz. The discharge was predominately ignited in positive half cycle of applied voltage with sinusoidal waveform. The temporal evolution of the discharge was investigated vertically along the discharge gap and radically on the dielectric surface by time resolved imaging. It is found that a discharge column with a diameter of 2 mm was ignited above the pin electrode and expanded toward a plate electrode. On the dielectric surface with space charge accumulation, plasma disk in terms of plasma ring was formed with radius up to 25 mm. The expansion velocity of plasma ring can reach a hypersonic speed of 3.0 km/s. The ionization wave due to electron diffusion is considered to be the mechanism for plasma ring formation and dynamics.

Complete velocity distribution in river cross-sections measured by acoustic instruments

USGS Publications Warehouse

Cheng, R.T.; Gartner, J.W.; ,

2003-01-01

To fully understand the hydraulic properties of natural rivers, velocity distribution in the river cross-section should be studied in detail. The measurement task is not straightforward because there is not an instrument that can measure the velocity distribution covering the entire cross-section. Particularly, the velocities in regions near the free surface and in the bottom boundary layer are difficult to measure, and yet the velocity properties in these regions play the most significant role in characterizing the hydraulic properties. To further characterize river hydraulics, two acoustic instruments, namely, an acoustic Doppler current profiler (ADCP), and a "BoogieDopp" (BD) were used on fixed platforms to measure the detailed velocity profiles across the river. Typically, 20 to 25 stations were used to represent a river cross-section. At each station, water velocity profiles were measured independently and/or concurrently by an ADCP and a BD. The measured velocity properties were compared and used in computation of river discharge. In a tow-tank evaluation of a BD, it has been confirmed that BD is capable of measuring water velocity at about 11 cm below the free-surface. Therefore, the surface velocity distribution across the river was extracted from the BD velocity measurements and used to compute the river discharge. These detailed velocity profiles and the composite velocity distribution were used to assess the validity of the classic theories of velocity distributions, conventional river discharge measurement methods, and for estimates of channel bottom roughness.

Noncontact methods for measuring water-surface elevations and velocities in rivers: Implications for depth and discharge extraction

USGS Publications Warehouse

Nelson, Jonathan M.; Kinzel, Paul J.; McDonald, Richard R.; Schmeeckle, Mark

2016-01-01

Recently developed optical and videographic methods for measuring water-surface properties in a noninvasive manner hold great promise for extracting river hydraulic and bathymetric information. This paper describes such a technique, concentrating on the method of infrared videog- raphy for measuring surface velocities and both acoustic (laboratory-based) and laser-scanning (field-based) techniques for measuring water-surface elevations. In ideal laboratory situations with simple flows, appropriate spatial and temporal averaging results in accurate water-surface elevations and water-surface velocities. In test cases, this accuracy is sufficient to allow direct inversion of the governing equations of motion to produce estimates of depth and discharge. Unlike other optical techniques for determining local depth that rely on transmissivity of the water column (bathymetric lidar, multi/hyperspectral correlation), this method uses only water-surface information, so even deep and/or turbid flows can be investigated. However, significant errors arise in areas of nonhydrostatic spatial accelerations, such as those associated with flow over bedforms or other relatively steep obstacles. Using laboratory measurements for test cases, the cause of these errors is examined and both a simple semi-empirical method and computational results are presented that can potentially reduce bathymetric inversion errors.

Atom Interferometry in a Warm Vapor

DOE PAGES

Biedermann, G. W.; McGuinness, H. J.; Rakholia, A. V.; ...

2017-04-17

Here, we demonstrate matter-wave interference in a warm vapor of rubidium atoms. Established approaches to light-pulse atom interferometry rely on laser cooling to concentrate a large ensemble of atoms into a velocity class resonant with the atom optical light pulse. In our experiment, we show that clear interference signals may be obtained without laser cooling. This effect relies on the Doppler selectivity of the atom interferometer resonance. Lastly, this interferometer may be configured to measure accelerations, and we demonstrate that multiple interferometers may be operated simultaneously by addressing multiple velocity classes.

Discharge dynamics of pin-to-plate dielectric barrier discharge at atmospheric pressure

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

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

2010-11-15

The discharge dynamics of pin-to-plate dielectric barrier discharge was studied in atmospheric helium at 20 kHz. The discharge was predominately ignited in positive half cycle of applied voltage with sinusoidal waveform. The temporal evolution of the discharge was investigated vertically along the discharge gap and radically on the dielectric surface by time resolved imaging. It is found that a discharge column with a diameter of 2 mm was ignited above the pin electrode and expanded toward a plate electrode. On the dielectric surface with space charge accumulation, plasma disk in terms of plasma ring was formed with radius up tomore » 25 mm. The expansion velocity of plasma ring can reach a hypersonic speed of 3.0 km/s. The ionization wave due to electron diffusion is considered to be the mechanism for plasma ring formation and dynamics.« less

Use of radars to monitor stream discharge by noncontact methods

USGS Publications Warehouse

Costa, J.E.; Cheng, R.T.; Haeni, F.P.; Melcher, N.; Spicer, K.R.; Hayes, E.; Plant, W.; Hayes, K.; Teague, C.; Barrick, D.

2006-01-01

Conventional measurements of river flows are costly, time‐consuming, and frequently dangerous. This report evaluates the use of a continuous wave microwave radar, a monostatic UHF Doppler radar, a pulsed Doppler microwave radar, and a ground‐penetrating radar to measure river flows continuously over long periods and without touching the water with any instruments. The experiments duplicate the flow records from conventional stream gauging stations on the San Joaquin River in California and the Cowlitz River in Washington. The purpose of the experiments was to directly measure the parameters necessary to compute flow: surface velocity (converted to mean velocity) and cross‐sectional area, thereby avoiding the uncertainty, complexity, and cost of maintaining rating curves. River channel cross sections were measured by ground‐penetrating radar suspended above the river. River surface water velocity was obtained by Bragg scattering of microwave and UHF Doppler radars, and the surface velocity data were converted to mean velocity on the basis of detailed velocity profiles measured by current meters and hydroacoustic instruments. Experiments using these radars to acquire a continuous record of flow were conducted for 4 weeks on the San Joaquin River and for 16 weeks on the Cowlitz River. At the San Joaquin River the radar noncontact measurements produced discharges more than 20% higher than the other independent measurements in the early part of the experiment. After the first 3 days, the noncontact radar discharge measurements were within 5% of the rating values. On the Cowlitz River at Castle Rock, correlation coefficients between the USGS stream gauging station rating curve discharge and discharge computed from three different Doppler radar systems and GPR data over the 16 week experiment were 0.883, 0.969, and 0.992. Noncontact radar results were within a few percent of discharge values obtained by gauging station, current meter, and hydroacoustic methods

Sediment motion and velocity in a glacier-fed stream

NASA Astrophysics Data System (ADS)

Mao, L.; Dell'Agnese, A.; Comiti, F.

2017-08-01

Current understanding of coarse sediment transport (e.g. threshold for motion, travel length and virtual velocity) in mountain rivers is still quite limited, and even less is known about glacial streams. However, the hydrological characteristics of these systems (strong daily discharge fluctuations, high water turbidity) pose challenges to the use of tracers to monitor bed sediment dynamics, as tagged clasts are usually located after bedload events when flow stage has receded, e.g. by means of portable antennas in the case of Passive Integrated Transponders (PIT). The use of stationary antennas, still scarcely in use worldwide, to detect PIT-tagged particles has potential advantages in glacier-fed streams. If water discharge is monitored continuously, a stationary antenna provides real time data on the actual discharge at the moment of tracer particles passage. This study focuses on incipient motion and virtual velocity of bed particles measured by a stationary antennas system in a steep mountain channel (Saldur River, drainage area 18.6 km2, Italian Alps) where significant daily discharge fluctuations and bedload transport occur as a result of a nivo-glacial regime. Four stationary antennas were installed 50-m apart in the study reach. A total of 629 PIT-tagged clasts were inserted in the studied reach between 2011 and 2014, ranging in size from 35 mm to 580 mm, with an overall recovery rate of around 44%. Critical discharge for sediment entrainment was obtained by detecting the movement of tracers placed immediately upstream of antennas. Virtual velocity was derived by knowing distances between the antennas and travel time of tracers. Results on initiation of motion show that the relationship between the size of transported tracers and the discharge measured at the time clasts were passing the stationary antenna is very weak. The influence of antecedent flows on incipient motion was thus investigated by dividing the highest discharge recorded between each PIT

Vaporization Would Cool Primary Battery

NASA Technical Reports Server (NTRS)

Bhandari, Pradeep; Miyake, Robert N.

1991-01-01

Temperature of discharging high-power-density primary battery maintained below specified level by evaporation of suitable liquid from jacket surrounding battery, according to proposal. Pressure-relief valve regulates pressure and boiling temperature of liquid. Less material needed in cooling by vaporization than in cooling by melting. Technique used to cool batteries in situations in which engineering constraints on volume, mass, and location prevent attachment of cooling fins, heat pipes, or like.

Vapor condensation on liquid surface due to laminar jet-induced mixing: The effects of system parameters

NASA Technical Reports Server (NTRS)

Lin, Chin-Shun; Hasan, Mohammad M.

1989-01-01

The effects of system parameters on the interface condensation rate in a laminar jet induced mixing tank are numerically studied. The physical system consists of a partially filled cylindrical tank with a slightly subcooled jet discharged from the center of the tank bottom toward the liquid-vapor interface which is at a saturation temperature corresponding to the constant tank pressure. Liquid is also withdrawn from the outer part of the tank bottom to maintain the constant liquid level. The jet velocity is selected to be low enough such that the free surface is approximately flat. The effect of vapor superheat is assumed to be negligible. Therefore, the interface condensation rate can be determined from the resulting temperature field in the liquid region alone. The nondimensional form of the steady state conservation equations are solved by a finite difference method for various system parameters including liquid height to tank diameter ratio, tank to jet diameter ratio, liquid inflow to outflow area ratio, and a heat leak parameter which characterizes the uniform wall heat flux. Detailed analyses based on the numerical solutions are performed and simplified equations are suggested for the prediction of condensation rate.

Field evaluation of shallow-water acoustic doppler current profiler discharge measurements

USGS Publications Warehouse

Rehmel, M.S.

2007-01-01

In 2004, the U.S. Geological Survey (USGS) Office of Surface Water staff and USGS Water Science employees began testing the StreamPro, an acoustic Doppler current profiler (ADCP) for shallow-water discharge measurements. Teledyne RD Instruments introduced the StreamPro in December of 2003. The StreamPro is designed to make a "moving boat" discharge measurement in streams with depths between 0.15 and 2 m. If the StreamPro works reliably in these conditions, it will allow for use of ADCPs in a greater number of streams than previously possible. Evaluation sites were chosen to test the StreamPro over a range of conditions. Simultaneous discharge measurements with mechanical and other acoustic meters, along with stable rating curves at established USGS streamflow-gaging stations, were used for comparisons. The StreamPro measurements ranged in mean velocity from 0.076 to 1.04 m/s and in discharge from 0.083 m 3/s to 43.4 m 3/s. Tests indicate that discharges measured with the StreamPro compare favorably to the discharges measured with the other meters when the mean channel velocity is greater than 0.25 m/s. When the mean channel velocity is less than 0.25 m/s, the StreamPro discharge measurements for individual transects have greater variability than those StreamPro measurements where the mean channel velocity is greater than 0.25 m/s. Despite this greater variation in individual transects, there is no indication that the StreamPro measured discharges (the mean discharge for all transects) are biased, provided that enough transects are used to determine the mean discharge. ?? 2007 ASCE.

Catalytic Reactor For Oxidizing Mercury Vapor

DOEpatents

Helfritch, Dennis J.

1998-07-28

A catalytic reactor (10) for oxidizing elemental mercury contained in flue gas is provided. The catalyst reactor (10) comprises within a flue gas conduit a perforated corona discharge plate (30a, b) having a plurality of through openings (33) and a plurality of projecting corona discharge electrodes (31); a perforated electrode plate (40a, b, c) having a plurality of through openings (43) axially aligned with the through openings (33) of the perforated corona discharge plate (30a, b) displaced from and opposing the tips of the corona discharge electrodes (31); and a catalyst member (60a, b, c, d) overlaying that face of the perforated electrode plate (40a, b, c) opposing the tips of the corona discharge electrodes (31). A uniformly distributed corona discharge plasma (1000) is intermittently generated between the plurality of corona discharge electrode tips (31) and the catalyst member (60a, b, c, d) when a stream of flue gas is passed through the conduit. During those periods when corona discharge (1000) is not being generated, the catalyst molecules of the catalyst member (60a, b, c, d) adsorb mercury vapor contained in the passing flue gas. During those periods when corona discharge (1000) is being generated, ions and active radicals contained in the generated corona discharge plasma (1000) desorb the mercury from the catalyst molecules of the catalyst member (60a, b, c, d), oxidizing the mercury in virtually simultaneous manner. The desorption process regenerates and activates the catalyst member molecules.

Shock vaporization of carbonate and sulfate minerals

NASA Astrophysics Data System (ADS)

Shen, A. H.; Ahrens, T. J.; O'Keefe, J. D.

2001-12-01

Strong shock waves induced by impacts can cause vaporization of rocks and minerals. The products of such process play important roles in planetary differentiation (Yakovlev et al., Geochem. International, 38, 1027, 2000) and in effecting the planetary climate. Many experiments and computer simulations have been performed to simulate the Chicxulub impact at Cretaceous/Tertiary boundary (see, for example, Pierazzo et al., J. Geophys. Res., 103, 28607, 1998 and Pope et al., J. Geophys. Res., 102, 21645, 1997). However, the pressure range for incipient and complete vaporization of carbonates and sulfates are not well constrained, especially, for minerals with various initial porosities. Furthermore, evidence for chemical species in the products of vaporized carbonate and sulfate minerals is almost non-existing. In this study, we employed published Hugoniot data for carbonate and sulfate minerals. By using the methods described in Ahrens (J. Appl. Phys., 43, 2443, 1972) and Ahrens and O'Keefe (The Moon, 4, 214, 1972), we calculated the entropy associated with the thermodynamic states produced by hypervelocity impacts at various velocities for carbonate and sulfate minerals with different initial porosities. The results were compared with the entropy of incipient vaporization and complete vaporization of these minerals to determine the degree of vaporization due to impacts. Moreover, these results are utilized to guide our experimental study in speciation reactions in shock-induced vaporization of carbonates and sulfates.

Effect of Liquid Surface Turbulent Motion on the Vapor Condensation in a Mixing Tank

NASA Technical Reports Server (NTRS)

Lin, C. S.; Hasan, M. M.

1991-01-01

The effect of liquid surface motion on the vapor condensation in a tank mixed by an axial turbulent jet is numerically investigated. The average value (over the interface area) of the root-mean-squared (rms) turbulent velocity at the interface is shown to be linearly increasing with decreasing liquid height and increasing jet diameter for a given tank size. The average rms turbulent velocity is incorporated in Brown et al. (1990) condensation correlation to predict the condensation of vapor on a liquid surface. The results are in good agreement with available condensation data.

High velocity pulsed wire-arc spray

NASA Technical Reports Server (NTRS)

Kincaid, Russell W. (Inventor); Witherspoon, F. Douglas (Inventor); Massey, Dennis W. (Inventor)

1999-01-01

Wire arc spraying using repetitively pulsed, high temperature gas jets, usually referred to as plasma jets, and generated by capillary discharges, substantially increases the velocity of atomized and entrained molten droplets. The quality of coatings produced is improved by increasing the velocity with which coating particles impact the coated surface. The effectiveness of wire-arc spraying is improved by replacing the usual atomizing air stream with a rapidly pulsed high velocity plasma jet. Pulsed power provides higher coating particle velocities leading to improved coatings. 50 micron aluminum droplets with velocities of 1500 m/s are produced. Pulsed plasma jet spraying provides the means to coat the insides of pipes, tubes, and engine block cylinders with very high velocity droplet impact.

Local velocity scaling in an impeller discharge flow in T400 vessel agitated by tooth impeller in a fully turbulent region

NASA Astrophysics Data System (ADS)

Šulc, Radek; Ditl, Pavel; Fořt, Ivan; Jašíkova, Darina; Kotek, Michal; Kopecký, Václav; Kysela, Bohuš

2018-06-01

Hydrodynamics and flow field were measured in an agitated vessel using 2-D Time Resolved Particle Image Velocimetry (2-D TR PIV). The experiments were carried out in a fully baffled cylindrical flat bottom vessel 400 mm in inner diameter agitated by a tooth impeller 133 mm in diameter. The velocity fields were measured in the impeller discharge flow for impeller rotation speeds from 300 rpm to 700 rpm and three liquids of different viscosities (i.e. (i) distilled water, ii) a 28% vol. aqueous solution of glycol, and iii) a 43% vol. aqueous solution of glycol), corresponding to the impeller Reynolds number in the range 68 000 < Re < 221 000. This Re range secures the fully-developed turbulent flow of agitated liquid. In accordance with the theory of mixing, the dimensionless mean and fluctuation velocities in the measured directions were found to be constant and independent of the impeller Reynolds number. On the basis of the test results the spatial distributions of dimensionless velocities were calculated. The radial turbulence intensity was found to be in the majority in the range from 0.3 to 0.9, which corresponds to the high level of this quantity.

Delineation of discharge areas of two contaminant plumes by use of diffusion samplers, Johns Pond, Cape Cod, Massachusetts, 1998

USGS Publications Warehouse

Savoie, Jennifer G.; LeBlanc, D.R.; Blackwood, D.S.; McCobb, T.D.; Rendigs, R. R.; Clifford, Scott

2000-01-01

Diffusion samplers were installed in the bottom of Johns Pond, Cape Cod, Massachusetts, to confirm that volatile organic compounds from the Storm Drain-5 (SD-5) plume emanating from the Massachusetts Military Reservation (MMR) were discharging into the pond. An array of 134 vapor-diffusion samplers was buried by divers about 0.5 feet below the pond bottom in the presumed discharge area of the SD-5 plume and left in place for about 2 weeks to equilibrate. Two areas of high concentrations of volatile organic compounds (VOCs) were identified. Samples from the first area contained trichloroethene (TCE) and tetrachloroethene with concentrations in vapor as high as 890 and 667 parts per billion by volume, respectively. This discharge area is about 1,000 feet wide, extends from 100 to 350 feet offshore, and is interpreted to be the discharge area of the SD-5 plume. Samples from the second area were located closer to shore than the discharge area of the SD-5 plume and contained unexpectedly high vapor concentrations of TCE (more than 40,000 parts per billion by volume). Ground-water samples collected with a drive-point sampler near the second area had aqueous TCE concentrations as high as 1,100 micrograms per liter. Subsequently, a more closely spaced array of 110 vapor-diffusion samplers was installed to map the area of elevated TCE concentrations . The discharge area detected with the samplers is about 75 feet wide and extends from about 25 to 200 feet offshore . TCE vapor concentrations in this area were as high as 42,800 parts per billion by volume. TCE concentrations in micrograms per liter in water-diffusion samples from 15 selected sites in the two discharge areas were about 35 times lower than the TCE concentrations in parts per billion by volume in corresponding vapor-diffusion samples. The difference in values is due to the volatile nature of TCE and the different units of measure. TCE was detected in diffusion samplers set in the pond water column above the

[Time lag effect between poplar' s sap flow velocity and microclimate factors in agroforestry system in West Liaoning Province].

PubMed

Di, Sun; Guan, De-xin; Yuan, Feng-hui; Wang, An-zhi; Wu, Jia-bing

2010-11-01

By using Granier's thermal dissipation probe, the sap flow velocity of the poplars in agroforestry system in west Liaoning was continuously measured, and the microclimate factors were measured synchronously. Dislocation contrast method was applied to analyze the sap flow velocity and corresponding air temperature, air humidity, net radiation, and vapor pressure deficit to discuss the time lag effect between poplar' s sap flow velocity and microclimate factors on sunny days. It was found that the poplar's sap flow velocity advanced of air temperature, air humidity, and vapor pressure deficit, and lagged behind net radiation. The sap flow velocity in June, July, August, and September was advanced of 70, 30, 50, and 90 min to air temperature, of 80, 30, 40, and 90 min to air humidity, and of 90, 50, 70, and 120 min to vapor pressure deficit, but lagged behind 10, 10, 40, and 40 min to net radiation, respectively. The time lag time of net radiation was shorter than that of air temperature, air humidity, and vapor pressure. The regression analysis showed that in the cases the time lag effect was contained and not, the determination coefficients between comprehensive microclimate factor and poplar's sap flow velocity were 0.903 and 0.855, respectively, indicating that when the time lag effect was contained, the determination coefficient was ascended by 2.04%, and thus, the simulation accuracy of poplar's sap flow velocity was improved.

Shock melting and vaporization of lunar rocks and minerals.

NASA Technical Reports Server (NTRS)

Ahrens, T. J.; O'Keefe, J. D.

1972-01-01

The entropy associated with the thermodynamic states produced by hypervelocity meteoroid impacts at various velocities are calculated for a series of lunar rocks and minerals and compared with the entropy values required for melting and vaporization. Taking into account shock-induced phase changes in the silicates, we calculate that iron meteorites impacting at speeds varying from 4 to 6 km/sec will produce shock melting in quartz, plagioclase, olivine, and pyroxene. Although calculated with less certainty, impact speeds required for incipient vaporization vary from 7 to 11 km/sec for the range of minerals going from quartz to periclase for aluminum (silicate-like) projectiles. The impact velocities, which are required to induce melting in a soil, are calculated to be in the range of 3 to 4 km/sec, provided thermal equilibrium is achieved in the shock state.

Biofiltration of methanol vapor

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

Shareefdeen, Z.; Baltzis, B.C.; Oh, Youngsook

1993-03-05

Biofiltration of solvent and fuel vapors may offer a cost-effective way to comply with increasingly strict air emission standards. An important step in the development of this technology is to derive and validate mathematical models of the biofiltration process for predictive and scaleup calculations. For the study of methanol vapor biofiltration, an 8-membered bacterial consortium was obtained from methanol-exposed soil. The bacteria were immobilized on solid support and packed into a 5-cm diameter, 60-cm-high column provided with appropriate flowmeters and sampling ports. The solid support was prepared by mixing two volumes of peat with three volumes of perlite particles. Twomore » series of experiments were performed. In the first, the inlet methanol concentration was kept constant while the superficial air velocity was varied from run to run. In the second series, the air flow rate (velocity) was kept constant while the inlet methanol concentration was varied. The unit proved effective in removing methanol at rates up to 112.8 g h[sup [minus]1] m[sup [minus]3] packing. A mathematical model has been derived and validated. The model described and predicted experimental results closely. Both experimental data and model predictions suggest that the methanol biofiltration process was limited by oxygen diffusion and methanol degradation kinetics.« less

Discharge rate measurements in a canal using radiotracer methods.

PubMed

Pant, H J; Goswami, Sunil; Biswal, Jayashree; Samantray, J S; Sharma, V K

2016-06-01

Discharge rates of water were measured in a canal using radiotracer methods with an objective to validate the efficacy of Concrete Volute Pumps (CVPs) installed at various pumping stations along the canal. Pulse velocity and dilution methods were applied to measure the discharge rates using Iodine-131 as a radiotracer. The discharge rate measured in one of the sections of the canal using the pulse velocity method was found to be 22.5m(3)/s, whereas the discharge rates measured using the dilution method in four different sections of the canal varied from 20.27 to 20.62m(3)/s with single CVP in operation. The standard error in discharge rate measurements using dilution method ranged from ±1.1 to ±1.8%. The experimentally measured values of the discharge rate were in good agreement with the design value of the discharge rate (20m(3)/s) thus validating the performance of the CVPs used in the canal. Copyright © 2016 Elsevier Ltd. All rights reserved.

Evaluation of the depth-integration method of measuring water discharge in large rivers

USGS Publications Warehouse

Moody, J.A.; Troutman, B.M.

1992-01-01

The depth-integration method oor measuring water discharge makes a continuos measurement of the water velocity from the water surface to the bottom at 20 to 40 locations or verticals across a river. It is especially practical for large rivers where river traffic makes it impractical to use boats attached to taglines strung across the river or to use current meters suspended from bridges. This method has the additional advantage over the standard two- and eight-tenths method in that a discharge-weighted suspended-sediment sample can be collected at the same time. When this method is used in large rivers such as the Missouri, Mississippi and Ohio, a microwave navigation system is used to determine the ship's position at each vertical sampling location across the river, and to make accurate velocity corrections to compensate for shift drift. An essential feature is a hydraulic winch that can lower and raise the current meter at a constant transit velocity so that the velocities at all depths are measured for equal lengths of time. Field calibration measurements show that: (1) the mean velocity measured on the upcast (bottom to surface) is within 1% of the standard mean velocity determined by 9-11 point measurements; (2) if the transit velocity is less than 25% of the mean velocity, then average error in the mean velocity is 4% or less. The major source of bias error is a result of mounting the current meter above a sounding weight and sometimes above a suspended-sediment sampling bottle, which prevents measurement of the velocity all the way to the bottom. The measured mean velocity is slightly larger than the true mean velocity. This bias error in the discharge is largest in shallow water (approximately 8% for the Missouri River at Hermann, MO, where the mean depth was 4.3 m) and smallest in deeper water (approximately 3% for the Mississippi River at Vickbsurg, MS, where the mean depth was 14.5 m). The major source of random error in the discharge is the natural

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.

Sensitivity of stand transpiration to wind velocity in a mixed broadleaved deciduous forest

Treesearch

Dohyoung Kim; Ram Oren; A. Christopher Oishi; Cheng-I Hsieh; Nathan Phillips; Kimberly A. Novick; Paul C. Stoy

2014-01-01

Wind velocity (U) within and above forest canopies can alter the coupling between the vapor-saturated sub-stomatal airspace and the drier atmosphere aloft, thereby influencing transpiration rates. In practice, however, the actual increase in transpiration with increasing U depends on the aerodynamic resistance (RA) to vapor transfer compared to canopy resistance to...

Vapor-dominated zones within hydrothermal systems: evolution and natural state

USGS Publications Warehouse

Ingebritsen, S.E.; Sorey, M.L.

1988-01-01

Three conceptual models illustrate the range of hydrothermal systems in which vapor-dominated conditions are found. The first model (model I) represents a system with an extensive near-vaporstatic vapor-dominated zone and limited liquid throughflow and is analogous to systems such as The Geysers, California. Models II and III represent systems with significant liquid throughflow and include steam-heated discharge features at higher elevations and high-chloride springs at lower elevations connected to and fed by a single circulation system at depth. In model II, as in model I, the vapor-dominated zone has a near-vaporstatic vertical pressure gradient and is generally underpressured with respect to local hydrostatic pressure. The vapor-dominated zone in model III is quite different, in that phase separation takes place at pressures close to local hydrostatic and the overall pressure gradient is near hydrostatic. -from Authors

Metal halides vapor lasers with inner reactor and small active volume.

NASA Astrophysics Data System (ADS)

Shiyanov, D. V.; Sukhanov, V. B.; Evtushenko, G. S.

2018-04-01

Investigation of the energy characteristics of copper, manganese, lead halide vapor lasers with inner reactor and small active volume 90 cm3 was made. The optimal operating pulse repetition rates, temperatures, and buffer gas pressure for gas discharge tubes with internal and external electrodes are determined. Under identical pump conditions, such systems are not inferior in their characteristics to standard metal halide vapor lasers. It is shown that the use of a zeolite halogen generator provides lifetime laser operation.

Effect of fuel vapor concentrations on combustor emissions and performance

NASA Technical Reports Server (NTRS)

Norgren, C. T.; Ingebo, R. D.

1973-01-01

Effects of fuel vaporization on the exhaust emission levels of oxides of nitrogen, carbon monoxide, total hydrocarbons, and smoke number were obtained in an experimental turbojet combustor segment. Two different fuel injectors were used in which liquid ASTM A-1 jet fuel and vapor propane fuel were independently controlled to simulate varying degrees of vaporization. Tests were conducted over a range of inlet-air temperatures from 478 to 700 K, pressures from 4 to 20 atm, and combustor reference velocities from 15.3 to 27.4 m/sec. Converting from liquid to complete vapor fuel resulted in oxides of nitrogen reductions of as much as 22 percent and smoke number reductions up to 51 percent. Supplement data are also presented on flame emissivity, flame temperature, and primary-zone liner wall temperatures.

Field and laboratory determination of water-surface elevation and velocity using noncontact measurements

USGS Publications Warehouse

Nelson, Jonathan M.; Kinzel, Paul J.; Schmeeckle, Mark Walter; McDonald, Richard R.; Minear, Justin T.

2016-01-01

Noncontact methods for measuring water-surface elevation and velocity in laboratory flumes and rivers are presented with examples. Water-surface elevations are measured using an array of acoustic transducers in the laboratory and using laser scanning in field situations. Water-surface velocities are based on using particle image velocimetry or other machine vision techniques on infrared video of the water surface. Using spatial and temporal averaging, results from these methods provide information that can be used to develop estimates of discharge for flows over known bathymetry. Making such estimates requires relating water-surface velocities to vertically averaged velocities; the methods here use standard relations. To examine where these relations break down, laboratory data for flows over simple bumps of three amplitudes are evaluated. As anticipated, discharges determined from surface information can have large errors where nonhydrostatic effects are large. In addition to investigating and characterizing this potential error in estimating discharge, a simple method for correction of the issue is presented. With a simple correction based on bed gradient along the flow direction, remotely sensed estimates of discharge appear to be viable.

Metal carbonyl vapor generation coupled with dielectric barrier discharge to avoid plasma quench for optical emission spectrometry.

PubMed

Cai, Yi; Li, Shao-Hua; Dou, Shuai; Yu, Yong-Liang; Wang, Jian-Hua

2015-01-20

The scope of dielectric barrier discharge (DBD) microplasma as a radiation source for optical emission spectrometry (OES) is extended by nickel carbonyl vapor generation. We proved that metal carbonyl completely avoids the extinguishing of plasma, and it is much more suitable for matching the DBD excitation and OES detection with respect to significant DBD quenching by concomitant hydrogen when hydride generation is used. A concentric quartz UV reactor allows sample solution to flow through the central channel wherein to efficiently receive the uniformly distributed UV irradiation in the confined cylindrical space between the concentric tubes, which facilitates effective carbonyl generation in a nickel solution. The carbonyl is transferred into the DBD excitation chamber by an argon stream for nickel excitation, and the characteristic emission of nickel at 232.0 nm is detected by a charge-coupled device (CCD) spectrometer. A 1.0 mL sample solution results in a linear range of 5-100 μg L(-1) along with a detection limit of 1.3 μg L(-1) and a precision of 2.4% RSD at 50 μg L(-1). The present DBD-OES system is validated by nickel in certified reference materials.

A one-dimensional with three-dimensional velocity space hybrid-PIC model of the discharge plasma in a Hall thruster

NASA Astrophysics Data System (ADS)

Shashkov, Andrey; Lovtsov, Alexander; Tomilin, Dmitry

2017-04-01

According to present knowledge, countless numerical simulations of the discharge plasma in Hall thrusters were conducted. However, on the one hand, adequate two-dimensional (2D) models require a lot of time to carry out numerical research of the breathing mode oscillations or the discharge structure. On the other hand, existing one-dimensional (1D) models are usually too simplistic and do not take into consideration such important phenomena as neutral-wall collisions, magnetic field induced by Hall current and double, secondary, and stepwise ionizations together. In this paper a one-dimensional with three-dimensional velocity space (1D3V) hybrid-PIC model is presented. The model is able to incorporate all the phenomena mentioned above. A new method of neutral-wall collisions simulation in described space was developed and validated. Simulation results obtained for KM-88 and KM-60 thrusters are in a good agreement with experimental data. The Bohm collision coefficient was the same for both thrusters. Neutral-wall collisions, doubly charged ions, and induced magnetic field were proved to stabilize the breathing mode oscillations in a Hall thruster under some circumstances.

Evaluation of the Acoustic Doppler Velocity Meter for Computation of Discharge Records at Three Sites in Colorado, 2004-2005

USGS Publications Warehouse

Stevens, Michael R.; Diaz, Paul; Smits, Dennis E.

2008-01-01

The U.S. Geological Survey (USGS), in cooperation with the Colorado Water Conservation Board, conducted a study in 2004-2005 at three sites in Colorado: Bear Creek at Morrison, Clear Creek near Empire, and Redlands Canal near Grand Junction. The study was done to evaluate acoustic Doppler velocity meter (ADVM) technology in different hydrologic settings that are characteristic of many Colorado streamflow-gaging sites. ADVMs have been tested and used extensively in many parts of the United States by USGS but not in Colorado where relatively small, shallow, clear, coarse-bed streams that ice up in the winter may affect the ADVM suitability. In this study, ADVM instrumentation was successfully used and discharge computations compared favorably, generally within 5 to 10 percent, with conventional USGS stage/discharge methods at the three Colorado sites. However, two factors, encountered in this study, may adversely affect the use of ADVM technology in Colorado. First, for some streams, the depth required (about 1.5 feet for a side-looking instrument) cannot be met during low-flow periods of the year. Second, cold temperatures and freezing-thawing cycles can produce ice effects that could prevent collection of usable ADVM (and stage) data.

Multifrequency characterization of viscoelastic polymers and vapor sensing based on SAW oscillators.

PubMed

Yadava, R D S; Kshetrimayum, Roshan; Khaneja, Mamta

2009-12-01

Simplified relations for the changes in SAW velocity and attenuation due to thin polymer coatings and vapor sorption are presented by making analytic approximations to the complex theoretical model developed earlier by Martin et al. [Anal. Chem. 66 (14) (1994) 2201-2219]. The approximate velocity relation is accurate within 4% for the film thicknesses up to 20% of the acoustic wavelength in the polymer film, and is useful for analyzing the mass loading, swelling and viscoelastic effects in SAW vapor sensors. The approximate attenuation relation is accurate within 20% for very thin films, (less than 2% of the acoustic wavelength in the film). Based on these relations, a new procedure for determination of polymer viscoelastic properties is described that exploits the frequency dependence of the velocity and attenuation perturbations, and employs multifrequency measurement on the same SAW platform. Expressions for individual contributions from the mass loading, film swelling and viscoelastic effects in SAW vapor sensors are derived, and their implications for the sensor design and operation are discussed. Also, a new SAW comb filter design is proposed that offers possibility for multimode SAW oscillator operation over a decade of frequency variation, and illustrates feasibility for experimental realization of wide bandwidth multifrequency SAW platforms.

Discharge ratings at gaging stations

USGS Publications Warehouse

Kennedy, E.J.

1984-01-01

A discharge rating is the relation of the discharge at a gaging station to stage and sometimes also to other variables. This chapter of 'Techniques of Water-Resources Investigations' describes the procedures commonly used to develop simple ratings where discharge is related only to stage and the most frequently encountered types of complex ratings where additional factors such as rate of change in stage, water-surface slope, or index velocity are used. Fundamental techniques of logarithmic plotting and the applications of simple storage routing to rating development are demonstrated. Computer applications, especially for handheld programmable calculators, and data handling are stressed.

Physical Vapor Deposition of Thin Films

NASA Astrophysics Data System (ADS)

Mahan, John E.

2000-01-01

A unified treatment of the theories, data, and technologies underlying physical vapor deposition methods With electronic, optical, and magnetic coating technologies increasingly dominating manufacturing in the high-tech industries, there is a growing need for expertise in physical vapor deposition of thin films. This important new work provides researchers and engineers in this field with the information they need to tackle thin film processes in the real world. Presenting a cohesive, thoroughly developed treatment of both fundamental and applied topics, Physical Vapor Deposition of Thin Films incorporates many critical results from across the literature as it imparts a working knowledge of a variety of present-day techniques. Numerous worked examples, extensive references, and more than 100 illustrations and photographs accompany coverage of: * Thermal evaporation, sputtering, and pulsed laser deposition techniques * Key theories and phenomena, including the kinetic theory of gases, adsorption and condensation, high-vacuum pumping dynamics, and sputtering discharges * Trends in sputter yield data and a new simplified collisional model of sputter yield for pure element targets * Quantitative models for film deposition rate, thickness profiles, and thermalization of the sputtered beam

Numerical simulation of superheated vapor bubble rising in stagnant liquid

NASA Astrophysics Data System (ADS)

Samkhaniani, N.; Ansari, M. R.

2017-09-01

In present study, the rising of superheated vapor bubble in saturated liquid is simulated using volume of fluid method in OpenFOAM cfd package. The surface tension between vapor-liquid phases is considered using continuous surface force method. In order to reduce spurious current near interface, Lafaurie smoothing filter is applied to improve curvature calculation. Phase change is considered using Tanasawa mass transfer model. The variation of saturation temperature in vapor bubble with local pressure is considered with simplified Clausius-Clapeyron relation. The couple velocity-pressure equation is solved using PISO algorithm. The numerical model is validated with: (1) isothermal bubble rising and (2) one-dimensional horizontal film condensation. Then, the shape and life time history of single superheated vapor bubble are investigated. The present numerical study shows vapor bubble in saturated liquid undergoes boiling and condensation. It indicates bubble life time is nearly linear proportional with bubble size and superheat temperature.

Discharge rating equation and hydraulic characteristics of standard Denil fishways

USGS Publications Warehouse

Odeh, M.

2003-01-01

This paper introduces a new equation to predict discharge capacity in the commonly used Denil fishway using water surface elevation in the upstream reservoir and fishway width and slope as the independent variables. A dimensionless discharge coefficient based only on the physical slope of the fishway is introduced. The discharge equation is based on flow physics, dimensional analysis, and experiments with three full-scale fishways of different sizes. Hydraulic characteristics of flow inside these fishways are discussed. Water velocities decreased by more than 50% and remained relatively unchanged in the fully developed flow downstream of the vena contracta region, near the upstream baffle where fish exit the fishway. Engineers and biologists need to be aware of this fact and ensure that fish can negotiate the vena contracta velocities rather than velocities within the developed flow region only. Discharge capacity was directly proportional to the fishway width and slope. The new equation is a design tool for engineers and field biologists, especially when designing a fishway based on flow availability in conjunction with the swimming capabilities of target fish species.

High intensity discharge device containing oxytrihalides

DOEpatents

Lapatovich, Walter P.; Keeffe, William M.; Liebermann, Richard W.; Maya, Jakob

1987-01-01

A fill composition for a high intensity discharge device including mercury, niobium oxytrihalide, and a molecular stabilization agent is provided. The molar ratio of niobium oxytrihalide to the molecular stabilization agent in the fill is in the range of from about 5:1 to about 7.5:1. Niobium oxytrihalide is present in the fill in sufficient amount to produce, by dissociation in the discharge, atomic niobium, niobium oxide, NbO, and niobium dioxide, NbO.sub.2, with the molar ratio of niobium-containing vapor species to mercury in the fill being in the range of from about 0.01:1 to about 0.50:1; and mercury pressure of about 1 to about 50 atmospheres at lamp operating temperature. There is also provided a high intensity discharge device comprising a sealed light-transmissive arc tube; the arc tube including the above-described fill; and an energizing means for producing an electric discharge within the arc tube.

High intensity discharge device containing oxytrihalides

DOEpatents

Lapatovich, W.P.; Keeffe, W.M.; Liebermann, R.W.; Maya, J.

1987-06-09

A fill composition for a high intensity discharge device including mercury, niobium oxytrihalide, and a molecular stabilization agent is provided. The molar ratio of niobium oxytrihalide to the molecular stabilization agent in the fill is in the range of from about 5:1 to about 7.5:1. Niobium oxytrihalide is present in the fill in sufficient amount to produce, by dissociation in the discharge, atomic niobium, niobium oxide, NbO, and niobium dioxide, NbO[sub 2], with the molar ratio of niobium-containing vapor species to mercury in the fill being in the range of from about 0.01:1 to about 0.50:1; and mercury pressure of about 1 to about 50 atmospheres at lamp operating temperature. There is also provided a high intensity discharge device comprising a sealed light-transmissive arc tube; the arc tube including the above-described fill; and an energizing means for producing an electric discharge within the arc tube. 7 figs.

Alumina Volatility in Water Vapor at Elevated Temperatures: Application to Combustion Environments

NASA Technical Reports Server (NTRS)

Opila, Elizabeth J.; Myers, Dwight L.

2003-01-01

The volatility of alumina in high temperature water vapor was determined by measuring weight loss of sapphire coupons at temperatures between 1250 and 1500 C, water vapor partial pressures between 0.15 and 0.68 atm in oxygen, at one atmosphere total pressure, and a gas velocity of 4.4 centimeters per second. The variation of the volatility with water vapor partial pressure was consistent with Al(OH)3(g) formation. The enthalpy of reaction to form Al(OH)3(g) from alumina and water vapor was found to be 210 plus or minus 20 kJ/mol. Surface rearrangement of ground sapphire surfaces increased with water vapor partial pressure, temperature and volatility rate. Recession rates of alumina due to volatility were determined as a function of water vapor partial pressure and temperature to evaluate limits for use of alumina in long term applications in combustion environments.

Generation of ozone by pulsed corona discharge over water surface in hybrid gas liquid electrical discharge reactor

NASA Astrophysics Data System (ADS)

Lukes, Petr; Clupek, Martin; Babicky, Vaclav; Janda, Vaclav; Sunka, Pavel

2005-02-01

Ozone formation by a pulse positive corona discharge generated in the gas phase between a planar high voltage electrode made from reticulated vitreous carbon and a water surface with an immersed ground stainless steel plate electrode was investigated under various operating conditions. The effects of gas flow rate (0.5-3 litre min-1), discharge gap spacing (2.5-10 mm), applied input power (2-45 W) and gas composition (oxygen containing argon or nitrogen) on ozone production were determined. Ozone concentration increased with increasing power input and with increasing discharge gap. The production of ozone was significantly affected by the presence of water vapour formed through vaporization of water at the gas-liquid interface by the action of the gas phase discharge. The highest energy efficiency for ozone production was obtained using high voltage pulses of approximately 150 ns duration in Ar/O2 mixtures with the maximum efficiency (energy yield) of 23 g kW h-1 for 40% argon content.

Ice shelf breaking and increase velocity of glacier: the view from analogue experiment

NASA Astrophysics Data System (ADS)

Corti, Giacomo; Iandelli, Irene

2013-04-01

Collapse of the Larsen II platform during the late 90s has generated an increase in velocity if ice sheet discharge, highlighting that these processes may strongly destabilize large ice masses speeding up the plateau discharge toward the sea. Parameters such as ice thickness, valley width and slope, ice pack dimensions may contribute to modulate the effect of increase in ice flow velocity following the removal of ice. We analyze this process through scale analogue models, aimed at reproducing the flow of ice from a plateau into the sea through a narrow valley. The ice is reproduced with a transparent silicone (Polydimethisiloxane), flowing at velocities of a few centimeters per hour and simulating natural velocities in the range of a few meters per year. Having almost the same density of the ice, PDMS floats on water and simulate the ice-shelf formation. Results of preliminary experimental series support that this methodology is able to reasonably reproduce the process and support a significant increase in velocity discharge following the removal of ice pack. Additional tests are designed to verify the influence of the above-mentioned parameters on the increase in ice velocity.

Assessment of velocity fields through open-channel flows with an empiric law.

PubMed

Bardiaux, J B; Vazquez, J; Mosé, R

2008-01-01

Most sewer managers are currently confronted with the evaluation of the water discharges, that flow through their networks or go to the discharge system, i.e. rivers in the majority of cases. In this context, the Urban Hydraulic Systems laboratory of the ENGEES is working on the relation between velocity fields and metrology assessment through a partnership with the Fluid and Solid Mechanics Institute of Strasbourg (IMFS). The responsibility is clearly to transform a velocity profile measurement, given by a Doppler sensor developed by the IMFS team, into a water discharge evaluation. The velocity distribution in a cross section of the flow in a channel has attracted the interests of many researchers over the years, due to its practical applications. In the case of free surface flows in narrow open channels the maximum velocity is below the free surface. This phenomenon, usually called "dip-phenomenon", amongst other things, raises the problem of the area explored in the section of measurements. The work presented here tries to create a simple relation making possible to associate the flow with the velocity distribution. This step allows to insert the sensor position into the flow calculation.

Investigations of dc electrical discharges in low-pressure sodium vapor with implications for AMTEC converters

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

Barkan, A.; Hunt, T.K.

1998-07-01

Upcoming designs for AMTEC modules capable of delivering as much as 150 watts will see the introduction of higher voltages into sodium vapor at pressures spanning a wide range. In theory, with any value for two out of three parameters: voltage, pressure, and electrode geometry, a value exists for the third parameter where DC electrical breakdown can occur; due to its low ionization energy, sodium vapor may be particularly susceptible to breakdown. This destructive event is not desirable in AMTEC modules, and sets a limit on the maximum voltage that can be built-up within any single enclosed module. An experimentalmore » cell was fabricated with representative electrode configurations and a separately heated sodium reservoir to test conditions typically expected during start-up, operation, and shutdown of AMTEC cells. Breakdown voltages were investigated in both sodium vapor and, for comparison, argon gas. The dependence on electrode material and polarity was also investigated. Additional information about leakage currents and the insulating properties of {alpha}-alumina in the presence of sodium vapor was collected, revealing a reversible tendency for conductive sodium films to build up under certain conditions, electrically shorting-out previously isolated components. In conclusion, safe operating limits on voltages, temperatures, and pressures are discussed.« less

Dynamic characteristics and mechanisms of compressible metallic vapor plume behaviors in transient keyhole during deep penetration fiber laser welding

NASA Astrophysics Data System (ADS)

Pang, Shengyong; Shao, Xinyu; Li, Wen; Chen, Xin; Gong, Shuili

2016-07-01

The compressible metallic vapor plume or plasma plume behaviors in the keyhole during deep penetration laser welding have significant effects on the joint quality. However, these behaviors and their responses to process parameter variations have not been well understood. In this paper, we first systematically study the dynamic characteristics and mechanisms of compressible metallic vapor plume behaviors in transient keyhole during fiber laser welding of 304 stainless steels based on a multiple timescale multiphase model. The time-dependent temperature, pressure, velocity and Mach number distributions of vapor plume under different process parameters are theoretically predicted. It is found that the distributions of the main physical characteristics of vapor plume such as pressure, velocity as well as Mach number in keyhole are usually highly uneven and highly time dependent. The peak difference of the velocity, pressure, temperature and Mach number of the vapor plume in a keyhole could be greater than 200 m/s, 20 kPa, 1000 K and 0.6 Mach, respectively. The vapor plume characteristics in a transient keyhole can experience significant changes within several hundreds of nanoseconds. The formation mechanisms of these dynamic characteristics are mainly due to the mesoscale keyhole hump (sized in several tens of microns) dynamics. It is also demonstrated that it is possible to suppress the oscillations of compressible vapor plume in the keyhole by improving the keyhole stability through decreasing the heat input. However, stabilizing the keyhole could only weaken, but not eliminate, the observed highly uneven and transient characteristics. This finding may pose new challenges for accurate experimental measurements of vapor plume induced by laser welding.

Measuring surface flow velocity with smartphones: potential for citizen observatories

NASA Astrophysics Data System (ADS)

Weijs, Steven V.; Chen, Zichong; Brauchli, Tristan; Huwald, Hendrik

2014-05-01

Stream flow velocity is an important variable for discharge estimation and research on sediment dynamics. Given the influence of the latter on rating curves (stage-discharge relations), and the relative scarcity of direct streamflow measurements, surface velocity measurements can offer important information for, e.g., flood warning, hydropower, and hydrological science and engineering in general. With the growing amount of sensing and computing power in the hands of more outdoorsy individuals, and the advances in image processing techniques, there is now a tremendous potential to obtain hydrologically relevant data from motivated citizens. This is the main focus of the interdisciplinary "WeSenseIt" project, a citizen observatory of water. In this subproject, we investigate the feasibility of stream flow surface velocity measurements from movie clips taken by (smartphone-) cameras. First results from movie-clip derived velocity information will be shown and compared to reference measurements.

Computing under-ice discharge: A proof-of-concept using hydroacoustics and the Probability Concept

NASA Astrophysics Data System (ADS)

Fulton, John W.; Henneberg, Mark F.; Mills, Taylor J.; Kohn, Michael S.; Epstein, Brian; Hittle, Elizabeth A.; Damschen, William C.; Laveau, Christopher D.; Lambrecht, Jason M.; Farmer, William H.

2018-07-01

Under-ice discharge is estimated using open-water reference hydrographs; however, the ratings for ice-affected sites are generally qualified as poor. The U.S. Geological Survey (USGS), in collaboration with the Colorado Water Conservation Board, conducted a proof-of-concept to develop an alternative method for computing under-ice discharge using hydroacoustics and the Probability Concept. The study site was located south of Minturn, Colorado (CO), USA, and was selected because of (1) its proximity to the existing USGS streamgage 09064600 Eagle River near Minturn, CO, and (2) its ease-of-access to verify discharge using a variety of conventional methods. From late September 2014 to early March 2015, hydraulic conditions varied from open water to under ice. These temporal changes led to variations in water depth and velocity. Hydroacoustics (tethered and uplooking acoustic Doppler current profilers and acoustic Doppler velocimeters) were deployed to measure the vertical-velocity profile at a singularly important vertical of the channel-cross section. Because the velocity profile was non-standard and cannot be characterized using a Power Law or Log Law, velocity data were analyzed using the Probability Concept, which is a probabilistic formulation of the velocity distribution. The Probability Concept-derived discharge was compared to conventional methods including stage-discharge and index-velocity ratings and concurrent field measurements; each is complicated by the dynamics of ice formation, pressure influences on stage measurements, and variations in cross-sectional area due to ice formation. No particular discharge method was assigned as truth. Rather one statistical metric (Kolmogorov-Smirnov; KS), agreement plots, and concurrent measurements provided a measure of comparability between various methods. Regardless of the method employed, comparisons between each method revealed encouraging results depending on the flow conditions and the absence or presence of ice

Computing under-ice discharge: A proof-of-concept using hydroacoustics and the Probability Concept

USGS Publications Warehouse

Fulton, John W.; Henneberg, Mark F.; Mills, Taylor J.; Kohn, Michael S.; Epstein, Brian; Hittle, Elizabeth A.; Damschen, William C.; Laveau, Christopher D.; Lambrecht, Jason M.; Farmer, William H.

2018-01-01

Under-ice discharge is estimated using open-water reference hydrographs; however, the ratings for ice-affected sites are generally qualified as poor. The U.S. Geological Survey (USGS), in collaboration with the Colorado Water Conservation Board, conducted a proof-of-concept to develop an alternative method for computing under-ice discharge using hydroacoustics and the Probability Concept.The study site was located south of Minturn, Colorado (CO), USA, and was selected because of (1) its proximity to the existing USGS streamgage 09064600 Eagle River near Minturn, CO, and (2) its ease-of-access to verify discharge using a variety of conventional methods. From late September 2014 to early March 2015, hydraulic conditions varied from open water to under ice. These temporal changes led to variations in water depth and velocity. Hydroacoustics (tethered and uplooking acoustic Doppler current profilers and acoustic Doppler velocimeters) were deployed to measure the vertical-velocity profile at a singularly important vertical of the channel-cross section. Because the velocity profile was non-standard and cannot be characterized using a Power Law or Log Law, velocity data were analyzed using the Probability Concept, which is a probabilistic formulation of the velocity distribution. The Probability Concept-derived discharge was compared to conventional methods including stage-discharge and index-velocity ratings and concurrent field measurements; each is complicated by the dynamics of ice formation, pressure influences on stage measurements, and variations in cross-sectional area due to ice formation.No particular discharge method was assigned as truth. Rather one statistical metric (Kolmogorov-Smirnov; KS), agreement plots, and concurrent measurements provided a measure of comparability between various methods. Regardless of the method employed, comparisons between each method revealed encouraging results depending on the flow conditions and the absence or presence of ice

Optical droplet vaporization of micron-sized perfluorocarbon droplets and their photoacoustic detection

NASA Astrophysics Data System (ADS)

Strohm, Eric; Rui, Min; Gorelikov, Ivan; Matsuura, Naomi; Kolios, Michael

2011-03-01

An acoustic and photoacoustic characterization of micron-sized perfluorocarbon (PFC) droplets is presented. PFC droplets are currently being investigated as acoustic and photoacoustic contrast agents and as cancer therapy agents. Pulse echo measurements at 375 MHz were used to determine the diameter, ranging from 3.2 to 6.5 μm, and the sound velocity, ranging from 311 to 406 m/s of nine droplets. An average sound velocity of 379 +/- 18 m/s was calculated for droplets larger than the ultrasound beam width of 4.0 μm. Optical droplet vaporization, where vaporization of a single droplet occurred upon laser irradiation of sufficient intensity, was verified using pulse echo acoustic methods. The ultrasonic backscatter amplitude, acoustic impedance and attenuation increased after vaporization, consistent with a phase change from a liquid to gas core. Photoacoustic measurements were used to compare the spectra of three droplets ranging in diameter from 3.0 to 6.2 μm to a theoretical model. Good agreement in the spectral features was observed over the bandwidth of the 375 MHz transducer.

Contribution for Iron Vapor and Radiation Distribution Affected by Current Frequency of Pulsed Arc

NASA Astrophysics Data System (ADS)

Shimokura, Takuya; Mori, Yusuke; Iwao, Toru; Yumoto, Motoshige

Pulsed GTA welding has been used for improvement of stability, weld speed, and heat input control. However, the temperature and radiation power of the pulsed arc have not been elucidated. Furthermore, arc contamination by metal vapor changes the arc characteristics, e.g. by increasing radiation power. In this case, the metal vapor in pulsed GTA welding changes the distribution of temperature and radiation power as a function of time. This paper presents the relation between metal vapor and radiation power at different pulse frequencies. We calculate the Fe vapor distribution of the pulsed current. Results show that the Fe vapor is transported at fast arc velocity during the peak current period. During the base current period, the Fe vapor concentration is low and distribution is diffuse. The transition of Fe vapor distribution does not follow the pulsed current; the radiation power density distribution differs for high frequencies and low frequencies. In addition, the Fe vapor and radiation distribution are affected by the pulsed arc current frequency.

Galactic water vapor emission: further observations of variability.

PubMed

Knowles, S H; Mayer, C H; Sullivan, W T; Cheung, A C

1969-10-10

Recent observations of the 1.35-centimeter line emission of water vapor from galactic sources show short-term variability in the spectra of several sources. Two additional sources, Cygnus 1 and NGC 6334N, have been observed, and the spectra of W49 and VY Canis Majoris were measured over a wider range of radial velocity.

Ignition of Fuel Vapors Beneath Titanium Aircraft Skins Exposed to Lightning

NASA Technical Reports Server (NTRS)

Kosvic, T. C.; Helgeson, N. L.; Gerstein, M.

1971-01-01

Hot-spot and puncture ignition of fuel vapors by simulated lightning discharges was studied experimentally. The influences of skin coating, skin structure, discharge polarity, skin thickness, discharge current level, and current duration were measured and interpreted. Ignition thresholds are reported for titanium alloy constructed as sheets, sheets coated with sealants, and sandwich skins. Results indicated that the ignition threshold charge transfer for coated sheets, honeycomb, and truss skins is respectively about 200%, 400%, 800% that of bare alloy sheet of .102 cm (.040 in.)-thickness. It was found that hot-spot ignition can occur well after termination of the arc, and that sandwich materials allow ignition only if punctured.

The cluster model of a hot dense vapor

NASA Astrophysics Data System (ADS)

Zhukhovitskii, D. I.

2015-04-01

We explore thermodynamic properties of a vapor in the range of state parameters where the contribution to thermodynamic functions from bound states of atoms (clusters) dominates over the interaction between the components of the vapor in free states. The clusters are assumed to be light and sufficiently "hot" for the number of bonds to be minimized. We use the technique of calculation of the cluster partition function for the cluster with a minimum number of interatomic bonds to calculate the caloric properties (heat capacity and velocity of sound) for an ideal mixture of the lightest clusters. The problem proves to be exactly solvable and resulting formulas are functions solely of the equilibrium constant of the dimer formation. These formulas ensure a satisfactory correlation with the reference data for the vapors of cesium, mercury, and argon up to moderate densities in both the sub- and supercritical regions. For cesium, we extend the model to the densities close to the critical one by inclusion of the clusters of arbitrary size. Knowledge of the cluster composition of the cesium vapor makes it possible to treat nonequilibrium phenomena such as nucleation of the supersaturated vapor, for which the effect of the cluster structural transition is likely to be significant.

The cluster model of a hot dense vapor

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

Zhukhovitskii, D. I., E-mail: dmr@ihed.ras.ru

2015-04-28

We explore thermodynamic properties of a vapor in the range of state parameters where the contribution to thermodynamic functions from bound states of atoms (clusters) dominates over the interaction between the components of the vapor in free states. The clusters are assumed to be light and sufficiently “hot” for the number of bonds to be minimized. We use the technique of calculation of the cluster partition function for the cluster with a minimum number of interatomic bonds to calculate the caloric properties (heat capacity and velocity of sound) for an ideal mixture of the lightest clusters. The problem proves tomore » be exactly solvable and resulting formulas are functions solely of the equilibrium constant of the dimer formation. These formulas ensure a satisfactory correlation with the reference data for the vapors of cesium, mercury, and argon up to moderate densities in both the sub- and supercritical regions. For cesium, we extend the model to the densities close to the critical one by inclusion of the clusters of arbitrary size. Knowledge of the cluster composition of the cesium vapor makes it possible to treat nonequilibrium phenomena such as nucleation of the supersaturated vapor, for which the effect of the cluster structural transition is likely to be significant.« less

Effects of surface dielectric barrier discharge on aerodynamic characteristic of train

NASA Astrophysics Data System (ADS)

Dong, Lei; Gao, Guoqiang; Peng, Kaisheng; Wei, Wenfu; Li, Chunmao; Wu, Guangning

2017-07-01

High-speed railway today has become an indispensable means of transportation due to its remarkable advantages, including comfortability, convenience and less pollution. The increase in velocity makes the air drag become the main source of energy consumption, leading to receiving more and more concerns. The surface dielectric barrier discharge has shown some unique characteristics in terms of active airflow control. In this paper, the influences of surface dielectric barrier discharge on the aerodynamic characteristics of a scaled train model have been studied. Aspects of the discharge power consumption, the temperature distribution, the velocity of induced flow and the airflow field around the train model were considered. The applied AC voltage was set in the range of 20 kV to 28 kV, with a fixed frequency of 9 kHz. Results indicated that the discharge power consumption, the maximum temperature and the induced flow velocity increased with increasing applied voltage. Mechanisms of applied voltage influencing these key parameters were discussed from the point of the equivalent circuit. The airflow field around the train model with different applied voltages was observed by the smoke visualization experiment. Finally, the effects of surface dielectric barrier discharge on the train drag reduction with different applied voltages were analyzed.

Coplanar surface barrier discharge ignited in water vapor—a selective source of OH radicals proved by (TA)LIF measurement

NASA Astrophysics Data System (ADS)

Procházka, V.; Tučeková, Z.; Dvořák, P.; Kováčik, D.; Slavíček, P.; Zahoranová, A.; Voráč, J.

2018-01-01

Coplanar dielectric barrier discharge (DBD) was ignited in pure water vapor at atmospheric pressure in order to generate highly oxidizing plasma with one specific type of reactive radicals. In order to prevent water condensation the used plasma reactor was heated to 120 {}\\circ C. The composition of the radical species in the discharge was studied by methods based on laser-induced fluorescence (LIF) and compared with analogous measurements realized in the same coplanar DBD ignited in air. Fast collisional processes and laser-surface interaction were taken into account during LIF data processing. It was found that coplanar DBD ignited in water vapor produces hydroxyl (OH) radicals with concentration in the order of 1020 m-3, which is 10× higher than the value measured in discharge in humid air (40% relative humidity at 21 {}\\circ C). The concentration of atomic hydrogen radicals in the DBD ignited in water vapor was below the detection limit, which proves that the generation of oxidizing plasma with dominance of one specific type of reactive radicals was achieved. The temporal evolution, spatial distribution, power dependence and rotational temperature of the OH radicals was determined in the DBD ignited in both water vapor and air.

Mass spectrometry for water vapor measurements in the UT/LS

NASA Astrophysics Data System (ADS)

Kaufmann, S.; Voigt, C.; Schäuble, D.; Schäfler, A.; Schlager, H.; Thornberry, T. D.; Fahey, D. W.

2012-12-01

Water vapor in the lower stratosphere plays a crucial role for the atmospheric radiation budget (Solomon et al., 2011). However, large uncertainties remain in measuring atmospheric water vapor mixing ratios below 10 ppmv typical for the lower stratosphere. To this end, we have developed the Atmospheric Ionization Mass Spectrometer (AIMS) for the accurate and fast detection of water vapor in the UT/LS from aircraft. In the AIMS instrument atmospheric air is directly ionized in a discharge ion source and the resulting water vapor clusters H3O+(H2O)n (n = 0..3) are detected with a linear quadrupole mass spectrometer as a direct measure of the atmospheric water vapor mixing ratio. AIMS is calibrated in-flight with a H2O calibration source using the catalytic reaction of H2 and O2 on a heated platinum surface to form gaseous H2O. This calibration setup combined with the water vapor mass spectrometry offers a powerful technical development in atmospheric hygrometry, enriching existing H2O measurement techniques by a new independent method. Here, we present AIMS water vapor measurements performed during the CONCERT2011 campaign (Contrail and Cirrus Experiment) with the DLR research aircraft Falcon. In September 2011 a deep stratospheric intrusion was probed over northern Europe with a dynamical tropopause lowered down to 6 km. We found sharp humidity gradients between tropospheric and stratospheric air at the edge of the tropopause fold, which we crossed 4 times at altitudes between 6 and 11 km. In the center of the tropopause fold, we measured water vapor mixing ratios down to 4 ppmv. The observed water vapor distribution is compared to water vapor analysis fields of the ECMWF's Integrated Forecast System (IFS) to evaluate the representation water vapor in this specific meteorological situation.

The Collapse of Vapor Bubbles in a Spatially Non-Uniform Flow

NASA Technical Reports Server (NTRS)

Hao, Y.; Prosperetti, A.

2000-01-01

Pressure gradients act differently on liquid particles and suspended bubbles and are, therefore, capable of inducing a relative motion between the phases even when no relative velocity initially exists. As a consequence of the enhanced heat transfer in the presence of convection, this fact may have a major impact on the evolution of a vapor bubble. The effect is particularly strong in the case of a collapsing bubble for which, due to the conservation of the system's impulse, the induced relative velocity tends to be magnified when the bubble volume shrinks. A practical application could be, for instance, the enhancement of the condensation rate of bubbles downstream of a heated region, thereby reducing the quality of a flowing liquid-vapor mixture. A simple model of the process, in which the bubble is assumed to be spherical and the flow potential, is developed in the paper.

Puncture discharges in surface dielectrics as contaminant sources in spacecraft environments

NASA Technical Reports Server (NTRS)

Yadlowsky, E. J.; Hazelton, R. C.; Churchill, R. J.

1978-01-01

Spacecraft in geosynchronous orbits are known to become charged to large negative potentials during the local midnight region of the satellite orbit. Such discharges have been studied by the electron beam irradiation of dielectric samples in a vacuum environment. In addition to static measurements and photographic examination of the puncture discharges in Teflon samples, the transient characteristics of the electrical discharges are determined from oscillographs of voltage and current and by charged particle measurements employing a biased Faraday cup and a retarding potential analyzer. Using these latter techniques, studies of angular and energy distributions of charged particles have indicated an initial burst of high energy electrons (5 x 10 to the 13th power per discharge at energies greater than 300 eV) followed by a less intense burst of lower energy negative particles. Positive ions are emitted from the discharge site in an initial high velocity burst followed by a lower velocity burst tentatively identified as carbon.

Discharge-measurement system using an acoustic Doppler current profiler with applications to large rivers and estuaries

USGS Publications Warehouse

Simpson, Michael R.; Oltmann, Richard N.

1993-01-01

Discharge measurement of large rivers and estuaries is difficult, time consuming, and sometimes dangerous. Frequently, discharge measurements cannot be made in tide-affected rivers and estuaries using conventional discharge-measurement techniques because of dynamic discharge conditions. The acoustic Doppler discharge-measurement system (ADDMS) was developed by the U.S. Geological Survey using a vessel-mounted acoustic Doppler current profiler coupled with specialized computer software to measure horizontal water velocity at 1-meter vertical intervals in the water column. The system computes discharge from water-and vessel-velocity data supplied by the ADDMS using vector-algebra algorithms included in the discharge-measurement software. With this system, a discharge measurement can be obtained by engaging the computer software and traversing a river or estuary from bank to bank; discharge in parts of the river or estuarine cross sections that cannot be measured because of ADDMS depth limitations are estimated by the system. Comparisons of ADDMS-measured discharges with ultrasonic-velocity-meter-measured discharges, along with error-analysis data, have confirmed that discharges provided by the ADDMS are at least as accurate as those produced using conventional methods. In addition, the advantage of a much shorter measurement time (2 minutes using the ADDMS compared with 1 hour or longer using conventional methods) has enabled use of the ADDMS for several applications where conventional discharge methods could not have been used with the required accuracy because of dynamic discharge conditions.

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).

Linear error analysis of slope-area discharge determinations

USGS Publications Warehouse

Kirby, W.H.

1987-01-01

The slope-area method can be used to calculate peak flood discharges when current-meter measurements are not possible. This calculation depends on several quantities, such as water-surface fall, that are subject to large measurement errors. Other critical quantities, such as Manning's n, are not even amenable to direct measurement but can only be estimated. Finally, scour and fill may cause gross discrepancies between the observed condition of the channel and the hydraulic conditions during the flood peak. The effects of these potential errors on the accuracy of the computed discharge have been estimated by statistical error analysis using a Taylor-series approximation of the discharge formula and the well-known formula for the variance of a sum of correlated random variates. The resultant error variance of the computed discharge is a weighted sum of covariances of the various observational errors. The weights depend on the hydraulic and geometric configuration of the channel. The mathematical analysis confirms the rule of thumb that relative errors in computed discharge increase rapidly when velocity heads exceed the water-surface fall, when the flow field is expanding and when lateral velocity variation (alpha) is large. It also confirms the extreme importance of accurately assessing the presence of scour or fill. ?? 1987.

The Observed Properties of Liquid Helium at the Saturated Vapor Pressure

NASA Astrophysics Data System (ADS)

Donnelly, Russell J.; Barenghi, Carlo F.

1998-11-01

The equilibrium and transport properties of liquid 4He are deduced from experimental observations at the saturated vapor pressure. In each case, the bibliography lists all known measurements. Quantities reported here include density, thermal expansion coefficient, dielectric constant, superfluid and normal fluid densities, first, second, third, and fourth sound velocities, specific heat, enthalpy, entropy, surface tension, ion mobilities, mutual friction, viscosity and kinematic viscosity, dispersion curve, structure factor, thermal conductivity, latent heat, saturated vapor pressure, thermal diffusivity and Prandtl number of helium I, and displacement length and vortex core parameter in helium II.

Cold cathode vacuum discharge tube

DOEpatents

Boettcher, Gordon E.

1998-01-01

A cold cathode vacuum discharge tube, and method for making same, with an interior surface of the trigger probe coated with carbon deposited by carbon vapor deposition (CVD) or diamond-like carbon (DLC) deposition. Preferably a solid graphite insert is employed in the probe-cathode structure in place of an aluminum bushing employed in the prior art. The CVD or DLC probe face is laser scribed to allow resistance trimming to match available trigger voltage signals and to reduce electrical aging.

Towards a Lithium Radiative / Vapor-Box Divertor

NASA Astrophysics Data System (ADS)

Goldston, Robert; Constantin, Marius; Jaworski, Michael; Myers, Rachel; Ono, Masayuki; Schwartz, Jacob; Scotti, Filippo; Qu, Zhaonan

2014-10-01

Recent research has indicated that the peak perpendicular heat flux on reactor divertor targets will be hundreds of MW/m2 in the absence of dissipation and/or spatial spreading. Thus we are attracted to both enhanced radiative cooling and continuous vapor shielding. Lithium particle lifetimes <=100 micro-sec enhance radiation efficiency at T < 10 eV, while lithium charge-exchange with neutral hydrogen may enhance radiative efficiency for T > 10 eV and n0/ni > 0.1. We are examining if the latter mechanism plays a role in the narrowing of the heat-flux footprint in lithiated NSTX discharges. In parallel we are investigating the possibility of immersing a reactor divertor leg in a channel of lithium vapor. If we approximate the vapor channel as in local equilibrium with lithium-wetted walls ranging from 300 oC at the entrance point to 950 oC 10m downstream in the parallel direction, we find that the vapor can both balance reactor levels of upstream plasma pressure and stop energetic ions and electrons with energies up to at least 25 keV, as might be produced in ELMs. Each 10 l/sec of lithium evaporated deep in the channel and recondensed in cooler regions spreads 100 MW over a much wider area than the original strike point. This work supported by US DOE Contract DE-AC02-09CH11466.

DISCHARGE AND DEPTH BEHIND A PARTIALLY BREACHED DAM.

USGS Publications Warehouse

Chen, Cheng-lung

1987-01-01

The role that the velocity-distribution correction factor plays in the determination of the flood discharge and corresponding flow depth behind a partially breached dam is investigated. Assumption of a uniformly progressive flow for an established dam-break flood in a rectangular channel of infinite extent leads to the formulation of a theoretical relation between the depth and velocity of flow expressed in differential form. Integrating this ordinary differential equation, one can express the velocity in terms of the depth.

Application of laser Doppler velocimeter to chemical vapor laser system

NASA Technical Reports Server (NTRS)

Gartrell, Luther R.; Hunter, William W., Jr.; Lee, Ja H.; Fletcher, Mark T.; Tabibi, Bagher M.

1993-01-01

A laser Doppler velocimeter (LDV) system was used to measure iodide vapor flow fields inside two different-sized tubes. Typical velocity profiles across the laser tubes were obtained with an estimated +/-1 percent bias and +/-0.3 to 0.5 percent random uncertainty in the mean values and +/-2.5 percent random uncertainty in the turbulence-intensity values. Centerline velocities and turbulence intensities for various longitudinal locations ranged from 13 to 17.5 m/sec and 6 to 20 percent, respectively. In view of these findings, the effects of turbulence should be considered for flow field modeling. The LDV system provided calibration data for pressure and mass flow systems used routinely to monitor the research laser gas flow velocity.

Oxidation of Ultra High Temperature Ceramics in Water Vapor

NASA Technical Reports Server (NTRS)

Nguyen, QuynhGiao N.; Opila, Elizabeth J.; Robinson, Raymond C.

2004-01-01

Ultra High Temperature Ceramics (UHTCs) including HfB2 + 20v/0 SiC (HS), ZrB2 + 20v/0 SiC (ZS), and ZrB2 + 30v/0 C + 14v/0 SiC (ZCS) have been investigated for use as potential aeropropulsion engine materials. These materials were oxidized in water vapor (90 percent) using a cyclic vertical furnace at 1 atm. The total exposure time was 10 h at temperatures of 1200, 1300, and 1400 C. CVD SiC was also evaluated as a baseline for comparison. Weight change, X-ray diffraction analyses, surface and cross-sectional SEM and EDS were performed. These results are compared with tests ran in a stagnant air furnace at temperatures of 1327 C for 100 min, and with high pressure burner rig (HPBR) results at 1100 and 1300 C at 6 atm for 50 h. Low velocity water vapor does not make a significant contribution to the oxidation rates of UHTCs when compared to stagnant air. The parabolic rate constants at 1300 C, range from 0.29 to 16.0 mg(sup 2)cm(sup 4)/h for HS and ZCS, respectively, with ZS results between these two values. Comparison of results for UHTCs tested in the furnace in 90 percent water vapor with HPBR results was difficult due to significant sample loss caused by spallation in the increased velocity of the HPBR. Total recession measurements are also reported for the two test environments.

Plasma-Chemical Synthesis of Oxide Powders Using Transformer-Coupled Discharge

NASA Astrophysics Data System (ADS)

M. Ulanov, I.; V. Isupov, M.; Yu Litvinsev, A.; A. Mischenko, P.

2013-04-01

An experimental investigation of transformer-coupled discharge in an Ar-O2 mixture with the addition of SiCl4, TiCl4 and ZrCl4 has been carried out under the atmospheric pressure of plasma-forming gases. Discharge power and discharge heat losses have been determined, and the dispersion and phase composition of reaction products (oxide powders) has been analyzed with SEM and X-ray diffraction analysis. Investigations reveal the formation of ultrafine oxide powders in the case of vaporized chloride (SiCl4 and TiCl4) injecting into the transformer coupled discharge. In the case of fine powder (ZrCl4) injection, full oxidation was not observed and reaction products consisted of a mixture of ZrO2 and ZrOCl2. A conclusion has been made regarding the perspectives of using transformer-coupled discharge to produce ultrafine oxide powders.

Cold cathode vacuum discharge tube

DOEpatents

Boettcher, G.E.

1998-03-10

A cold cathode vacuum discharge tube, and method for making same, are disclosed with an interior surface of the trigger probe coated with carbon deposited by carbon vapor deposition (CVD) or diamond-like carbon (DLC) deposition. Preferably a solid graphite insert is employed in the probe-cathode structure in place of an aluminum bushing employed in the prior art. The CVD or DLC probe face is laser scribed to allow resistance trimming to match available trigger voltage signals and to reduce electrical aging. 15 figs.

Cold cathode vacuum discharge tube

DOEpatents

Boettcher, G.E.

1998-04-14

A cold cathode vacuum discharge tube, and method for making same, with an interior surface of the trigger probe coated with carbon deposited by chemical vapor deposition (CVD) or diamond-like carbon (DLC) deposition are disclosed. Preferably a solid graphite insert is employed in the probe-cathode structure in place of an aluminum bushing employed in the prior art. The CVD or DLC probe face is laser scribed to allow resistance trimming to match available trigger voltage signals and to reduce electrical aging. 14 figs.

Acceleration processes in the quasi-steady magnetoplasmadynamic discharge. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Boyle, M. J.

1974-01-01

The flow field characteristics within the discharge chamber and exhaust of a quasi-steady magnetoplasmadynamic (MPD) arcjet were examined to clarify the nature of the plasma acceleration process. The observation of discharge characteristics unperturbed by insulator ablation and terminal voltage fluctuations, first requires the satisfaction of three criteria: the use of refractory insulator materials; a mass injection geometry tailored to provide propellant to both electrode regions of the discharge; and a cathode of sufficient surface area to permit nominal MPD arcjet operation for given combinations of arc current and total mass flow. The axial velocity profile and electromagnetic discharge structure were measured for an arcjet configuration which functions nominally at 15.3 kA and 6 g/sec argon mass flow. An empirical two-flow plasma acceleration model is advanced which delineates inner and outer flow regions and accounts for the observed velocity profile and calculated thrust of the accelerator.

Estimating discharge in rivers using remotely sensed hydraulic information

USGS Publications Warehouse

Bjerklie, D.M.; Moller, D.; Smith, L.C.; Dingman, S.L.

2005-01-01

A methodology to estimate in-bank river discharge exclusively from remotely sensed hydraulic data is developed. Water-surface width and maximum channel width measured from 26 aerial and digital orthophotos of 17 single channel rivers and 41 SAR images of three braided rivers were coupled with channel slope data obtained from topographic maps to estimate the discharge. The standard error of the discharge estimates were within a factor of 1.5-2 (50-100%) of the observed, with the mean estimate accuracy within 10%. This level of accuracy was achieved using calibration functions developed from observed discharge. The calibration functions use reach specific geomorphic variables, the maximum channel width and the channel slope, to predict a correction factor. The calibration functions are related to channel type. Surface velocity and width information, obtained from a single C-band image obtained by the Jet Propulsion Laboratory's (JPL's) AirSAR was also used to estimate discharge for a reach of the Missouri River. Without using a calibration function, the estimate accuracy was +72% of the observed discharge, which is within the expected range of uncertainty for the method. However, using the observed velocity to calibrate the initial estimate improved the estimate accuracy to within +10% of the observed. Remotely sensed discharge estimates with accuracies reported in this paper could be useful for regional or continental scale hydrologic studies, or in regions where ground-based data is lacking. ?? 2004 Elsevier B.V. All rights reserved.

Temporal changes in VOC discharge to surface water from a fractured rock aquifer during well installation and operation, Greenville, South Carolina

USGS Publications Warehouse

Vroblesky, D.A.; Robertson, J.F.

1996-01-01

Analysis of the vapor in passive vapor samplers retrieved from a streambed in fractured rock terrain implied that volatile organic carbon (VOC) discharge from ground water to surface water substantially increased following installation of a contaminant recovery well using air rotary drilling. The air rotary technique forced air into the aquifer near the stream. The injection produced an upward hydraulic gradient that appears to have transported water and contaminants from deeper parts of the aquifer through fractures into shallow parts of the aquifer. Once in the shallow flow regime, the contamination was transported to the stream, where it discharged during the next several weeks following well installation. After the recovery well was activated and began continuously pumping contaminated ground water to a treatment facility, the VOC concentrations in the stream bottom passive vapor samplers decreased to below detectable concentrations, suggesting that the withdrawal had captured the contaminated ground water that previously had discharged to the stream.

CFD Modeling of LNG Spill: Humidity Effect on Vapor Dispersion

NASA Astrophysics Data System (ADS)

Giannissi, S. G.; Venetsanos, A. G.; Markatos, N.

2015-09-01

The risks entailed by an accidental spill of Liquefied Natural Gas (LNG) should be indentified and evaluated, in order to design measures for prevention and mitigation in LNG terminals. For this purpose, simulations are considered a useful tool to study LNG spills and to understand the mechanisms that influence the vapor dispersion. In the present study, the ADREA-HF CFD code is employed to simulate the TEEX1 experiment. The experiment was carried out at the Brayton Fire Training Field, which is affiliated with the Texas A&M University system and involves LNG release and dispersion over water surface in open- obstructed environment. In the simulation the source was modeled as a two-phase jet enabling the prediction of both the vapor dispersion and the liquid pool spreading. The conservation equations for the mixture are solved along with the mass fraction for natural gas. Due to the low prevailing temperatures during the spill ambient humidity condenses and this might affect the vapor dispersion. This effect was examined in this work by solving an additional conservation equation for the water mass fraction. Two different models were tested: the hydrodynamic equilibrium model which assumes kinetic equilibrium between the phases and the non hydrodynamic equilibrium model, in order to assess the effect of slip velocity on the prediction. The slip velocity is defined as the difference between the liquid phase and the vapor phase and is calculated using the algebraic slip model. Constant droplet diameter of three different sizes and a lognormal distribution of the droplet diameter were applied and the results are discussed and compared with the measurements.

Relationship of sediment discharge to streamflow

USGS Publications Warehouse

Colby, B.R.

1956-01-01

The relationship between rate of sediment discharge and rate of water discharge at a cross section of a stream is frequently expressed by an average curve. This curve is the sediment rating curve. It has been widely used in the computation of average sediment discharge from water discharge for periods when sediment samples were not collected. This report discusses primarily the applications of sediment rating curves for periods during which at least occasional sediment samples were collected. Because sediment rating curves are of many kinds, the selection of the correct kind for each use is important. Each curve should be carefully prepared. In particular, the correct dependent variable must be used or the slope of the sediment rating curve may be incorrect for computing sediment discharges. Sediment rating curves and their applications were studied for the following gaging stations: 1. Niobrara River near Cody, Nebr. 2. Colorado River near Grand Canyon, Ariz. 3. Rio Grande at San Martial, N. Mex. 4. Rio Puerto near Bernardo, N. Mex. 5. White River near Kadoka, S. Dak. 6. Sandusky River near Fremont, Ohio Except for the Sandusky River and the Rio Puerco, which transport mostly fine sediment, one instantaneous sediment rating curve was prepared for the discharge of suspended sands, at each station, and another for the discharge of sediment finer than 0.082 millimeter. Each curve was studied separately, and by trial-end-error multiple correlation some of the factors that cause scatter from the sediment rating curves were determined. Average velocity at the cross section, Water temperature, and erratic fluctuations in concentration seemed to be the three major factors that caused departures from the sediment rating curves for suspended sands. The concentration of suspended sands varied with about the 2.8 power of the mean velocity for the four sediment, rating curves for suspended sands. The effect of water temperature was not so consistent as that of velocity and

[Study of high temperature water vapor concentration measurement method based on absorption spectroscopy].

PubMed

Chen, Jiu-ying; Liu, Jian-guo; He, Jun-feng; He, Ya-bai; Zhang, Guang-le; Xu, Zhen-yu; Gang, Qiang; Wang, Liao; Yao, Lu; Yuan, Song; Ruan, Jun; Dai, Yun-hai; Kan, Rui-feng

2014-12-01

Tunable diode laser absorption spectroscopy (TDLAS) has been developed to realize the real-time and dynamic measurement of the combustion temperature, gas component concentration, velocity and other flow parameters, owing to its high sensitivity, fast time response, non-invasive character and robust nature. In order to obtain accurate water vapor concentration at high temperature, several absorption spectra of water vapor near 1.39 μm from 773 to 1273 K under ordinary pressure were recorded in a high temperature experiment setup using a narrow band diode laser. The absorbance of high temperature absorption spectra was calculated by combined multi-line nonlinear least squares fitting method. Two water vapor absorption lines near 7154.35 and 7157.73 cm(-1) were selected for measurement of water vapor at high temperature. A model method for high temperature water vapor concentration was first proposed. Water vapor concentration from the model method at high temperature is in accordance with theoretical reasoning, concentration measurement standard error is less than 0.2%, and the relative error is less than 6%. The feasibility of this measuring method is verified by experiment.

[Evaluation of vaporizers by anesthetic gas monitors corrected with a new method for preparation of calibration gases].

PubMed

Kurashiki, T

1996-11-01

For resolving the discrepancy of concentrations found among anesthetic gas monitors, the author proposed a new method using a vaporizer as a standard anesthetic gas generator for calibration. In this method, the carrier gas volume is measured by a mass flow meter (SEF-510 + FI-101) installed before the inlet of the vaporizer. The vaporized weight of volatile anesthetic agent is simultaneously measured by an electronic force balance (E12000S), on which the vaporizer is placed directly. The molar percent of the anesthetic is calculated using these data and is transformed into the volume percent. These gases discharging from the vaporizer are utilized for calibrating anesthetic gas monitors. These monitors are normalized by the linear equation describing the relationship between concentrations of calibration gases and readings of the anesthetic gas monitors. By using normalized monitors, flow rate-concentration performance curves of several anesthetic vaporizers were obtained. The author concludes that this method can serve as a standard in evaluating anesthetic vaporizers.

The development of substitute inks and controls for reducing workplace concentrations of organic solvent vapors in a vinyl shower curtain printing plant.

PubMed

Piltingsrud, Harley V; Zimmer, Anthony T; Rourke, Aaron B

2003-08-01

During the summer of 1994, football players at a practice field reported noxious odors in the area. Ohio Environmental Protection Agency (OEPA) investigations of industries surrounding the field included a printing facility producing vinyl shower curtains with screen-printed designs. Though not the source of the odor, they were discharging volatile organic compounds directly to the environs in violation of OEPA regulations. To achieve compliance they installed a catalytic oxidizer for treating discharged air. Due to high equipment costs, the capacity of the installed catalytic oxidizer resulted in a substantial reduction in discharged air flow rates and increased solvent vapor concentrations within the workplace. Vapor levels caused worker discomfort, prompting a request for assistance from the Ohio Bureau of Workers Compensation. The vapor concentrations were found to exceed NIOSH, OSHA, and ACGIH acceptable exposure levels. The workers were then required to wear organic vapor removing respirators full-time while printing as a temporary protective measure. The company requested NIOSH assistance in finding methods to reduce solvent vapor concentrations. NIOSH studies included the identification of the sources and relative magnitude of solvent emissions from the printing process, the design of controls for the emissions, and the development of substitute inks using non-photochemically reactive solvents. The new ink system and controls allowed OEPA removal of the requirement for the treatment of discharged air and substantial increases in dilution ventilation. Increased ventilation would permit reduction in worker exposures to less than 1/3 mixture TLV levels and removal of requirements for respirator usage. This solution was the result of a comprehensive review of all facets of the problem, including OEPA regulations. It also required cooperative work between the company and federal, state, and local governmental agencies.

Multi-cathode metal vapor arc ion source

DOEpatents

Brown, Ian G.; MacGill, Robert A.

1988-01-01

An ion generating apparatus utilizing a vacuum chamber, a cathode and an anode in the chamber. A source of electrical power produces an arc or discharge between the cathode and anode. The arc is sufficient to vaporize a portion of the cathode to form a plasma. The plasma is directed to an extractor which separates the electrons from the plasma, and accelerates the ions to produce an ion beam. One embodiment of the appaatus utilizes a multi-cathode arrangement for interaction with the anode.

Evaluation of the Ott Hydromet Qliner for measuring discharge in laboratory and field conditions

USGS Publications Warehouse

McVay, Jason C.

2015-01-01

The U.S. Geological Survey, in collaboration with the University of Iowa IIHR – Hydroscience and Engineering, evaluated the use of the Ott Hydromet Qliner using laboratory flume tests along with field validation tests. Analysis of the flume testing indicates the velocities measured by the Qliner at a 40-second exposure time results in higher dispersion of velocities from the mean velocity of data collected with a 5-minute exposure time. The percent data spread from the mean of a 100-minute mean of Qliner velocities for a 40-second exposure time averaged 16.6 percent for the entire vertical, and a 5-minute mean produced a 6.2 percent data spread from the 100-minute mean. This 16.6 percent variation in measured velocity would result in a 3.32 percent variation in computed discharge assuming 25 verticals while averaging 4 bins in each vertical. The flume testing also provided results that indicate the blanking distance of 0.20 meters is acceptable when using beams 1 and 2, however beam 3 is negatively biased near the transducer and the 0.20-meter blanking distance is not sufficient. Field testing included comparing the measured discharge by the Qliner to the discharge measured by a Price AA mechanical current meter and a Teledyne RDI Rio Grande 1200 kilohertz acoustic Doppler current profiler. The field tests indicated a difference between the discharges measured with the Qliner and the field reference discharge between -14.0 and 8.0 percent; however the average percent difference for all 22 field comparisons was 0.22, which was not statistically significant.

Acoustic emission by self-organising effects of micro-hollow cathode discharges

NASA Astrophysics Data System (ADS)

Kotschate, Daniel; Gaal, Mate; Kersten, Holger

2018-04-01

We designed micro-hollow cathode discharge prototypes under atmospheric pressure and investigated their acoustic characteristics. For the acoustic model of the discharge, we correlated the self-organisation effect of the current density distribution with the ideal model of an acoustic membrane. For validation of the obtained model, sound particle velocity spectroscopy was used to detect and analyse the acoustic emission experimentally. The results have shown a behaviour similar to the ideal acoustic membrane. Therefore, the acoustic excitation is decomposable into its eigenfrequencies and predictable. The model was unified utilising the gas exhaust velocity caused by the electrohydrodynamic force. The results may allow a contactless prediction of the current density distribution by measuring the acoustic emission or using the micro-discharge as a tunable acoustic source for specific applications as well.

Highly ionized physical vapor deposition plasma source working at very low pressure

NASA Astrophysics Data System (ADS)

Stranak, V.; Herrendorf, A.-P.; Drache, S.; Cada, M.; Hubicka, Z.; Tichy, M.; Hippler, R.

2012-04-01

Highly ionized discharge for physical vapor deposition at very low pressure is presented in the paper. The discharge is generated by electron cyclotron wave resonance (ECWR) which assists with ignition of high power impulse magnetron sputtering (HiPIMS) discharge. The magnetron gun (with Ti target) was built into the single-turn coil RF electrode of the ECWR facility. ECWR assistance provides pre-ionization effect which allows significant reduction of pressure during HiPIMS operation down to p = 0.05 Pa; this is nearly more than an order of magnitude lower than at typical pressure ranges of HiPIMS discharges. We can confirm that nearly all sputtered particles are ionized (only Ti+ and Ti++ peaks are observed in the mass scan spectra). This corresponds well with high plasma density ne ˜ 1018 m-3, measured during the HiPIMS pulse.

Some Results from Studies of Microwave Discharges in Liquid Heavy Hydrocarbons

NASA Astrophysics Data System (ADS)

Averin, K. A.; Lebedev, Yu. A.; Shakhatov, V. A.

2018-01-01

Some results from studies of microwave discharges in heavy hydrocarbons are presented. Microwave energy was introduced into liquid hydrocarbon via a coaxial line. The pressure above the liquid surface was equal to the atmospheric pressure. The discharge was ignited in a mixture of argon and hydrocarbon vapor. Argon was supplied through a channel in the central conductor of the coaxial line. The emission spectra of discharges in different liquid hydrocarbons were studied. It is shown that the emission spectra mainly consist of sequences of Swan bands, while radiation of other plasma components is on the noise level. Spectra of plasma emission are presented for discharges in liquid n-heptane, nefras, and C-9 oil used to produce chemical fibers. The rotational (gas) and vibrational temperatures are determined by processing the observed spectra.

An Experimental Study of the Ionization of Low-Density Gas Flows by Induced Discharges

NASA Technical Reports Server (NTRS)

Barger, R. L.; Brooks, J. D.; Beasley, W. D.

1960-01-01

Induced discharges are advantageous for ionizing low-density flows in that they introduce no electrode contamination into the flow and they provide a relatively high degree of ionization with good coupling of power into the gas. In this investigation a 40-megacycle oscillator was used to produce and maintain induced discharges in argon and mercury-vapor flows. Methods for preventing blowout of the discharge were determined, and power measurements were made with an in-line wattmeter. Some results with damped oscillations pulsed at 1,000 pulses per second are also presented.

Development and Application of a Three-Dimensional Finite Element Vapor Intrusion Model

PubMed Central

Pennell, Kelly G.; Bozkurt, Ozgur; Suuberg, Eric M.

2010-01-01

Details of a three-dimensional finite element model of soil vapor intrusion, including the overall modeling process and the stepwise approach, are provided. The model is a quantitative modeling tool that can help guide vapor intrusion characterization efforts. It solves the soil gas continuity equation coupled with the chemical transport equation, allowing for both advective and diffusive transport. Three-dimensional pressure, velocity, and chemical concentration fields are produced from the model. Results from simulations involving common site features, such as impervious surfaces, porous foundation sub-base material, and adjacent structures are summarized herein. The results suggest that site-specific features are important to consider when characterizing vapor intrusion risks. More importantly, the results suggest that soil gas or subslab gas samples taken without proper regard for particular site features may not be suitable for evaluating vapor intrusion risks; rather, careful attention needs to be given to the many factors that affect chemical transport into and around buildings. PMID:19418819

Characteristics of Capacity Coupled Discharge in Atmospheric Pressure Air

NASA Astrophysics Data System (ADS)

Sasaki, Tadahiro; Omukai, Reina; Mukaigawa, Seiji; Takaki, Koichi; Fujiwara, Tamiya; Mase, Hiroshi; Sato, Noriyoshi

This paper describes characteristics of capacity coupled discharge in atmospheric pressure air with focusing influence of gap length of point-to-plane electrode configuration on input power into the discharge. The discharge can be quenched in short time duration by inserting a small capacitance capacitor between the electrode and the ground. We employed a needle electrode and a coaxial cable as the quenching capacitor. The discharge was successfully quenched within 25 ns in duration according to 9.4 pF in a capacitance of the quenching capacitor. The discharge was classified as two modes; a spark mode and a corona mode. At the spark mode, the power consumed in the discharge plasma was almost 10 times as large as that of a conventional dielectric barrier discharge. At the corona mode, the consumed energy was almost same value with that of the dielectric barrier discharge. A velocity of the discharge development was obtained to be 3×105 m/s by an optical measurement.

Role of turbulence fluctuations on uncertainties of acoutic Doppler current profiler discharge measurements

USGS Publications Warehouse

Tarrab, Leticia; Garcia, Carlos M.; Cantero, Mariano I.; Oberg, Kevin

2012-01-01

This work presents a systematic analysis quantifying the role of the presence of turbulence fluctuations on uncertainties (random errors) of acoustic Doppler current profiler (ADCP) discharge measurements from moving platforms. Data sets of three-dimensional flow velocities with high temporal and spatial resolution were generated from direct numerical simulation (DNS) of turbulent open channel flow. Dimensionless functions relating parameters quantifying the uncertainty in discharge measurements due to flow turbulence (relative variance and relative maximum random error) to sampling configuration were developed from the DNS simulations and then validated with field-scale discharge measurements. The validated functions were used to evaluate the role of the presence of flow turbulence fluctuations on uncertainties in ADCP discharge measurements. The results of this work indicate that random errors due to the flow turbulence are significant when: (a) a low number of transects is used for a discharge measurement, and (b) measurements are made in shallow rivers using high boat velocity (short time for the boat to cross a flow turbulence structure).

Velocity bias induced by flow patterns around ADCPs and associated deployment platforms

USGS Publications Warehouse

Mueller, David S.

2015-01-01

Velocity measurements near the Acoustic Doppler Current Profiler (ADCP) are important for mapping surface currents, measuring velocity and discharge in shallow streams, and providing accurate estimates of discharge in the top unmeasured portion of the water column. Improvements to ADCP performance permit measurement of velocities much closer (5 cm) to the transducer than has been possible in the past (25 cm). Velocity profiles collected by the U.S. Geological Survey (USGS) with a 1200 kHz Rio Grande Zedhead ADCP in 2002 showed a negative bias in measured velocities near the transducers. On the basis of these results, the USGS initiated a study combining field, laboratory, and numerical modeling data to assess the effect of flow patterns caused by flow around the ADCP and deployment platforms on velocities measured near the transducers. This ongoing study has shown that the negative bias observed in the field is due to the flow pattern around the ADCP. The flow pattern around an ADCP violates the basic assumption of flow homogeneity required for an accurate three-dimensional velocity solution. Results, to date (2014), have indicated velocity biases within the measurable profile, due to flow disturbance, for the TRDI 1200 kHz Rio Grande Zedhead and the SonTek RiverSurveyor M9 ADCPs. The flow speed past the ADCP, the mount and the deployment platform have also been shown to play an important role in the magnitude and extent of the velocity bias.

Role of Co-Vapors in Vapor Deposition Polymerization

PubMed Central

Lee, Ji Eun; Lee, Younghee; Ahn, Ki-Jin; Huh, Jinyoung; Shim, Hyeon Woo; Sampath, Gayathri; Im, Won Bin; Huh, Yang–Il; Yoon, Hyeonseok

2015-01-01

Polypyrrole (PPy)/cellulose (PPCL) composite papers were fabricated by vapor phase polymerization. Importantly, the vapor-phase deposition of PPy onto cellulose was assisted by employing different co-vapors namely methanol, ethanol, benzene, water, toluene and hexane, in addition to pyrrole. The resulting PPCL papers possessed high mechanical flexibility, large surface-to-volume ratio, and good redox properties. Their main properties were highly influenced by the nature of the co-vaporized solvent. The morphology and oxidation level of deposited PPy were tuned by employing co-vapors during the polymerization, which in turn led to change in the electrochemical properties of the PPCL papers. When methanol and ethanol were used as co-vapors, the conductivities of PPCL papers were found to have improved five times, which was likely due to the enhanced orientation of PPy chain by the polar co-vapors with high dipole moment. The specific capacitance of PPCL papers obtained using benzene, toluene, water and hexane co-vapors was higher than those of the others, which is attributed to the enlarged effective surface area of the electrode material. The results indicate that the judicious choice and combination of co-vapors in vapor-deposition polymerization (VDP) offers the possibility of tuning the morphological, electrical, and electrochemical properties of deposited conducting polymers. PMID:25673422

Discharge estimation from H-ADCP measurements in a tidal river subject to sidewall effects and a mobile bed

NASA Astrophysics Data System (ADS)

Sassi, M. G.; Hoitink, A. J. F.; Vermeulen, B.; Hidayat, null

2011-06-01

Horizontal acoustic Doppler current profilers (H-ADCPs) can be employed to estimate river discharge based on water level measurements and flow velocity array data across a river transect. A new method is presented that accounts for the dip in velocity near the water surface, which is caused by sidewall effects that decrease with the width to depth ratio of a channel. A boundary layer model is introduced to convert single-depth velocity data from the H-ADCP to specific discharge. The parameters of the model include the local roughness length and a dip correction factor, which accounts for the sidewall effects. A regression model is employed to translate specific discharge to total discharge. The method was tested in the River Mahakam, representing a large river of complex bathymetry, where part of the flow is intrinsically three-dimensional and discharge rates exceed 8000 m3 s-1. Results from five moving boat ADCP campaigns covering separate semidiurnal tidal cycles are presented, three of which are used for calibration purposes, whereas the remaining two served for validation of the method. The dip correction factor showed a significant correlation with distance to the wall and bears a strong relation to secondary currents. The sidewall effects appeared to remain relatively constant throughout the tidal cycles under study. Bed roughness length is estimated at periods of maximum velocity, showing more variation at subtidal than at intratidal time scales. Intratidal variations were particularly obvious during bidirectional flow conditions, which occurred only during conditions of low river discharge. The new method was shown to outperform the widely used index velocity method by systematically reducing the relative error in the discharge estimates.

Theory of supercompression of vapor bubbles and nanoscale thermonuclear fusion

NASA Astrophysics Data System (ADS)

Nigmatulin, Robert I.; Akhatov, Iskander Sh.; Topolnikov, Andrey S.; Bolotnova, Raisa Kh.; Vakhitova, Nailya K.; Lahey, Richard T.; Taleyarkhan, Rusi P.

2005-10-01

This paper provides the theoretical basis for energetic vapor bubble implosions induced by a standing acoustic wave. Its primary goal is to describe, explain, and demonstrate the plausibility of the experimental observations by Taleyarkhan et al. [Science 295, 1868 (2002); Phys. Rev. E 69, 036109 (2004)] of thermonuclear fusion for imploding cavitation bubbles in chilled deuterated acetone. A detailed description and analysis of these data, including a resolution of the criticisms that have been raised, together with some preliminary HYDRO code simulations, has been given by Nigmatulin et al. [Vestnik ANRB (Ufa, Russia) 4, 3 (2002); J. Power Energy 218-A, 345 (2004)] and Lahey et al. [Adv. Heat Transfer (to be published)]. In this paper a hydrodynamic shock (i.e., HYDRO) code model of the spherically symmetric motion for a vapor bubble in an acoustically forced liquid is presented. This model describes cavitation bubble cluster growth during the expansion period, followed by a violent implosion during the compression period of the acoustic cycle. There are two stages of the bubble dynamics process. The first, low Mach number stage, comprises almost all the time of the acoustic cycle. During this stage, the radial velocities are much less than the sound speeds in the vapor and liquid, the vapor pressure is very close to uniform, and the liquid is practically incompressible. This process is characterized by the inertia of the liquid, heat conduction, and the evaporation or condensation of the vapor. The second, very short, high Mach number stage is when the radial velocities are the same order, or higher, than the sound speeds in the vapor and liquid. In this stage high temperatures, pressures, and densities of the vapor and liquid take place. The model presented herein has realistic equations of state for the compressible liquid and vapor phases, and accounts for nonequilibrium evaporation/condensation kinetics at the liquid/vapor interface. There are interacting

Experimental study of the spill and vaporization of a volatile liquid.

PubMed

Bohl, Douglas; Jackson, Gregory

2007-02-09

Pool and vapor cloud characteristics of an acetone spill issuing from the downstream wall of a flow obstruction oriented perpendicular to a uniform flow were investigated experimentally. Data indicate that the spill event was largely governed by the temperature of the surface in relation to the boiling point of the spilled liquid. The free stream velocity (ranging from 0.75 to 3.0m/s) also impacted the spreading of the spill. Planar laser-induced fluorescence (PLIF) was used to measure acetone vapor concentrations during the transient pool spreading and vaporization in a window 60cm long by 50cm high and located downstream of the 16cm high obstruction. The recirculation region induced by the flow obstruction caused upstream transport of the acetone vapor along the spill surface, after which it was convected vertically along the obstruction wall before being entrained into the flow and convected downstream. The recirculating flow caused regions of vapor within the flammability limits to be localized near the flow obstruction. These regions moved into and out of the measurement plane by large three-dimensional flow structures. The flammable region of the evolved vapor cloud was observed to grow well past the downstream edge of the measurement domain. With decreasing wind speeds, both the mass of acetone vapor within the flammability limits and the total spill event time increased significantly. The data presented herein provides a basis for validating future spill models of hazardous chemical releases, where complex turbulent flow modeling must be coupled with spill spreading and vaporization dynamics.

Physics-based agent to simulant correlations for vapor phase mass transport.

PubMed

Willis, Matthew P; Varady, Mark J; Pearl, Thomas P; Fouse, Janet C; Riley, Patrick C; Mantooth, Brent A; Lalain, Teri A

2013-12-15

Chemical warfare agent simulants are often used as an agent surrogate to perform environmental testing, mitigating exposure hazards. This work specifically addresses the assessment of downwind agent vapor concentration resulting from an evaporating simulant droplet. A previously developed methodology was used to estimate the mass diffusivities of the chemical warfare agent simulants methyl salicylate, 2-chloroethyl ethyl sulfide, di-ethyl malonate, and chloroethyl phenyl sulfide. Along with the diffusivity of the chemical warfare agent bis(2-chloroethyl) sulfide, the simulant diffusivities were used in an advection-diffusion model to predict the vapor concentrations downwind from an evaporating droplet of each chemical at various wind velocities and temperatures. The results demonstrate that the simulant-to-agent concentration ratio and the corresponding vapor pressure ratio are equivalent under certain conditions. Specifically, the relationship is valid within ranges of measurement locations relative to the evaporating droplet and observation times. The valid ranges depend on the relative transport properties of the agent and simulant, and whether vapor transport is diffusion or advection dominant. Published by Elsevier B.V.

Self-tuning method for monitoring the density of a gas vapor component using a tunable laser

DOEpatents

Hagans, Karla; Berzins, Leon; Galkowski, Joseph; Seng, Rita

1996-01-01

The present invention relates to a vapor density monitor and laser atomic absorption spectroscopy method for highly accurate, continuous monitoring of vapor densities, composition, flow velocity, internal and kinetic temperatures and constituent distributions. The vapor density monitor employs a diode laser, preferably of an external cavity design. By using a diode laser, the vapor density monitor is significantly less expensive and more reliable than prior art vapor density monitoring devices. In addition, the compact size of diode lasers enables the vapor density monitor to be portable. According to the method of the present invention, the density of a component of a gas vapor is calculated by tuning the diode laser to a frequency at which the amount of light absorbed by the component is at a minimum or a maximum within about 50 MHz of that frequency. Laser light from the diode laser is then transmitted at the determined frequency across a predetermined pathlength of the gas vapor. By comparing the amount of light transmitted by the diode laser to the amount of light transmitted after the laser light passes through the gas vapor, the density of the component can be determined using Beer's law.

Self-tuning method for monitoring the density of a gas vapor component using a tunable laser

DOEpatents

Hagans, K.; Berzins, L.; Galkowski, J.; Seng, R.

1996-08-27

The present invention relates to a vapor density monitor and laser atomic absorption spectroscopy method for highly accurate, continuous monitoring of vapor densities, composition, flow velocity, internal and kinetic temperatures and constituent distributions. The vapor density monitor employs a diode laser, preferably of an external cavity design. By using a diode laser, the vapor density monitor is significantly less expensive and more reliable than prior art vapor density monitoring devices. In addition, the compact size of diode lasers enables the vapor density monitor to be portable. According to the method of the present invention, the density of a component of a gas vapor is calculated by tuning the diode laser to a frequency at which the amount of light absorbed by the component is at a minimum or a maximum within about 50 MHz of that frequency. Laser light from the diode laser is then transmitted at the determined frequency across a predetermined pathlength of the gas vapor. By comparing the amount of light transmitted by the diode laser to the amount of light transmitted after the laser light passes through the gas vapor, the density of the component can be determined using Beer`s law. 6 figs.

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.

A three-dimensional phase field model for nanowire growth by the vapor-liquid-solid mechanism

NASA Astrophysics Data System (ADS)

Wang, Yanming; Ryu, Seunghwa; McIntyre, Paul C.; Cai, Wei

2014-07-01

We present a three-dimensional multi-phase field model for catalyzed nanowire (NW) growth by the vapor-liquid-solid (VLS) mechanism. The equation of motion contains both a Ginzburg-Landau term for deposition and a diffusion (Cahn-Hilliard) term for interface relaxation without deposition. Direct deposition from vapor to solid, which competes with NW crystal growth through the molten catalyst droplet, is suppressed by assigning a very small kinetic coefficient at the solid-vapor interface. The thermodynamic self-consistency of the model is demonstrated by its ability to reproduce the equilibrium contact angles at the VLS junction. The incorporation of orientation dependent gradient energy leads to faceting of the solid-liquid and solid-vapor interfaces. The model successfully captures the curved shape of the NW base and the Gibbs-Thomson effect on growth velocity.

Fuel for cyclones: The water vapor budget of a hurricane as dependent on its movement

NASA Astrophysics Data System (ADS)

Makarieva, Anastassia M.; Gorshkov, Victor G.; Nefiodov, Andrei V.; Chikunov, Alexander V.; Sheil, Douglas; Nobre, Antonio Donato; Li, Bai-Lian

2017-09-01

Despite the dangers associated with tropical cyclones and their rainfall, the origin of the moisture in these storms, which include destructive hurricanes and typhoons, remains surprisingly uncertain. Existing studies have focused on the region 40-400 km from a cyclone's center. It is known that the rainfall within this area cannot be explained by local processes alone but requires imported moisture. Nonetheless, the dynamics of this imported moisture appears unknown. Here, considering a region up to three thousand kilometers from cyclone center, we analyze precipitation, atmospheric moisture and movement velocities for severe tropical cyclones - North Atlantic hurricanes. Our findings indicate that even over such large areas a hurricane's rainfall cannot be accounted for by concurrent evaporation. We propose instead that a hurricane consumes pre-existing atmospheric water vapor as it moves. The propagation velocity of the cyclone, i.e. the difference between its movement velocity and the mean velocity of the surrounding air (steering flow), determines the water vapor budget. Water vapor available to the hurricane through its movement makes the hurricane self-sufficient at about 700 km from the hurricane center obviating the need to concentrate moisture from greater distances. Such hurricanes leave a dry wake, whereby rainfall is suppressed by up to 40% compared to the local long-term mean. The inner radius of this dry footprint approximately coincides with the hurricane's radius of water self-sufficiency. We discuss how Carnot efficiency considerations do not constrain the power of such open systems. Our findings emphasize the incompletely understood role and importance of atmospheric moisture stocks and dynamics in the behavior of severe tropical cyclones.

Review of critical flow rate, propagation of pressure pulse, and sonic velocity in two-phase media

NASA Technical Reports Server (NTRS)

Hsu, Y.

1972-01-01

For single-phase media, the critical discharge velocity, the sonic velocity, and the pressure pulse propagation velocity can be expressed in the same form by assuming isentropic, equilibria processes. In two-phase mixtures, the same concept is not valid due to the existence of interfacial transports of momentum, heat, and mass. Thus, the three velocities should be treated differently and separately for each particular condition, taking into account the various transport processes involved under that condition. Various attempts are reviewed to predict the critical discharge rate or the propagation velocities by considering slip ratio (momentum change), evaporation (mass and heat transport), flow pattern, etc. Experimental data were compared with predictions based on various theorems. The importance is stressed of the time required to achieve equilibrium as compared with the time available during the process, for example, of passing a pressure pulse.

Chemical Production of Vibrationally Excited Carbon Monoxide from Carbon Vapor and Molecular Oxygen Precursors

NASA Astrophysics Data System (ADS)

Frederickson, Kraig; Musci, Ben; Rich, J. William; Adamovich, Igor

2015-09-01

Recent results demonstrating the formation of vibrationally excited carbon monoxide from carbon vapor and molecular oxygen will be presented. Previous reaction dynamics simulations and crossed molecular beam experiments have shown that gas-phase reaction of carbon atoms and molecular oxygen produces vibrationally excited carbon monoxide. The present work examines the product distribution of this reaction in a collision dominated environment, at a pressure of several Torr. Carbon vapor is produced in an AC arc discharge in argon buffer operated at a voltage of approximately 1 kV and current of 10 A, and mixed with molecular oxygen, which may also be excited by an auxiliary RF discharge, in a flowing chemical reactor. Identification of chemical reaction products and inference of their vibrational populations is performed by comparing infrared emission spectra of the flow in the reactor, taken by a Fourier Transform IR spectrometer, with synthetic spectra. Estimates of vibrationally excited carbon monoxide concentration and relative vibrational level populations will be presented.

Remote measurement of river discharge using thermal particle image velocimetry (PIV) and various sources of bathymetric information

USGS Publications Warehouse

Legleiter, Carl; Kinzel, Paul J.; Nelson, Jonathan M.

2017-01-01

Although river discharge is a fundamental hydrologic quantity, conventional methods of streamgaging are impractical, expensive, and potentially dangerous in remote locations. This study evaluated the potential for measuring discharge via various forms of remote sensing, primarily thermal imaging of flow velocities but also spectrally-based depth retrieval from passive optical image data. We acquired thermal image time series from bridges spanning five streams in Alaska and observed strong agreement between velocities measured in situ and those inferred by Particle Image Velocimetry (PIV), which quantified advection of thermal features by the flow. The resulting surface velocities were converted to depth-averaged velocities by applying site-specific, calibrated velocity indices. Field spectra from three clear-flowing streams provided strong relationships between depth and reflectance, suggesting that, under favorable conditions, spectrally-based bathymetric mapping could complement thermal PIV in a hybrid approach to remote sensing of river discharge; this strategy would not be applicable to larger, more turbid rivers, however. A more flexible and efficient alternative might involve inferring depth from thermal data based on relationships between depth and integral length scales of turbulent fluctuations in temperature, captured as variations in image brightness. We observed moderately strong correlations for a site-aggregated data set that reduced station-to-station variability but encompassed a broad range of depths. Discharges calculated using thermal PIV-derived velocities were within 15% of in situ measurements when combined with depths measured directly in the field or estimated from field spectra and within 40% when the depth information also was derived from thermal images. The results of this initial, proof-of-concept investigation suggest that remote sensing techniques could facilitate measurement of river discharge.

Edge-to-center plasma density ratios in two-dimensional plasma discharges

NASA Astrophysics Data System (ADS)

Lucken, R.; Croes, V.; Lafleur, T.; Raimbault, J.-L.; Bourdon, A.; Chabert, P.

2018-03-01

Edge-to-center plasma density ratios—so-called h factors—are important parameters for global models of plasma discharges as they are used to calculate the plasma losses at the reactor walls. There are well-established theories for h factors in the one-dimensional (1D) case. The purpose of this paper is to establish h factors in two-dimensional (2D) systems, with guidance from a 2D particle-in-cell (PIC) simulation. We derive analytical solutions of a 2D fluid theory that includes the effect of ion inertia, but assumes a constant (independent of space) ion collision frequency (using an average ion velocity) across the discharge. Predicted h factors from this 2D fluid theory have the same order of magnitude and the same trends as the PIC simulations when the average ion velocity used in the collision frequency is set equal to the ion thermal velocity. The best agreement is obtained when the average ion velocity varies with pressure (but remains independent of space), going from half the Bohm velocity at low pressure, to the thermal velocity at high pressure. The analysis also shows that a simple correction of the widely-used 1D heuristic formula may be proposed to accurately incorporate 2D effects.

The effect of humidity on ionic wind velocity in ambient air

NASA Astrophysics Data System (ADS)

Chen, She; Nobelen, J. C. P. Y.; Nijdam, S.

2016-09-01

Due to the evolution of portable electronics and LED lightning system, advances in air cooling technologies must also keep pace. Active cooling by ionic wind, which is usually generated by corona discharge, can greatly reduce the noise and lifetime issues compared to the mechanical fans. The wind is induced when a gas discharge is formed, and neutral molecules gain their energy by the momentum transfer of ion-neutral collisions. However, there is few discussion about the effect of gas composition such as humidity on the wind generation and the physical mechanism is not clear. In the experiment, a positive 5-20 kV DC voltage is applied to the needle-cylinder electrodes with separation of 20 mm. The ionic wind velocity is measured by hot wire anemometry. As the relative humidity (RH) in the ambient air increases, the velocity is found to be severely inhibited. The current is also measured between the cylinder electrode and earth. The results show that the DC component of corona current decreases when RH increases. Since both the discharge current and the ion mobility are reduced when RH increases, their combined effects determine the ionic wind velocity. This work is supported by STW project 13651.

Potential impacts of discharging tertiary-treated wastewater into Port Royal Sound, South Carolina

USGS Publications Warehouse

Speiran, G.K.; Belval, D.L.

1985-01-01

An assessment of physical characteristics of Port Royal Sound was combined with the results of a dye tracer study and with data collected from a previous environmental study to describe the impact on the water quality from discharging tertiary treated wastewater into the sound. Calculated velocities for the time of maximum velocity in the tidal cycle ranged from 2.32 ft/sec near the bottom to 4.65 ft/sec near the surface of the sound in a cross section in the vicinity of a proposed wastewater outfall. Vertical velocity distributions calculated for the time of maximum velocity were similar at all stations at which velocities were measured except the station in shallow water near the shore. A recent bathymetric chart of the vicinity of the proposed outfall indicates that a bar extends farther along the northern shore of Hilton Head Island than indicated on earlier nautical charts of Port Royal Sound. Continued extension of this bar could alter the impact on water quality from discharge of treated wastewater into the sound. Further study may be needed to monitor changes in the bar if the outfall is located between the bar and Hilton Head Island. Conservative calculations based on the results of the dye tracer study indicate that the discharge of 10.9 million gallons/day of wastewater having concentrations of biochemical oxygen demand and suspended solids of 15 mg/L will result in a maximum cumulative increase in concentrations of biochemical oxygen demand of < 0.01 mg/L and no increase in concentrations of suspended solids at high slack tide in the part of Port Royal Sound most affected by the proposed wastewater discharge. (Author 's abstract)

The suitability of using dissolved gases to determine groundwater discharge to high gradient streams

USGS Publications Warehouse

Gleeson, Tom; Manning, Andrew H.; Popp, Andrea; Zane, Mathew; Clark, Jordan F.

2018-01-01

Determining groundwater discharge to streams using dissolved gases is known to be useful over a wide range of streamflow rates but the suitability of dissolved gas methods to determine discharge rates in high gradient mountain streams has not been sufficiently tested, even though headwater streams are critical as ecological habitats and water resources. The aim of this study is to test the suitability of using dissolved gases to determine groundwater discharge rates to high gradient streams by field experiments in a well-characterized, high gradient mountain stream and a literature review. At a reach scale (550 m) we combined stream and groundwater radon activity measurements with an in-stream SF6 tracer test. By means of numerical modeling we determined gas exchange velocities and derived very low groundwater discharge rates (∼15% of streamflow). These groundwater discharge rates are below the uncertainty range of physical streamflow measurements and consistent with temperature, specific conductance and streamflow measured at multiple locations along the reach. At a watershed-scale (4 km), we measured CFC-12 and δ18O concentrations and determined gas exchange velocities and groundwater discharge rates with the same numerical model. The groundwater discharge rates along the 4 km stream reach were highly variable, but were consistent with the values derived in the detailed study reach. Additionally, we synthesized literature values of gas exchange velocities for different stream gradients which show an empirical relationship that will be valuable in planning future dissolved gas studies on streams with various gradients. In sum, we show that multiple dissolved gas tracers can be used to determine groundwater discharge to high gradient mountain streams from reach to watershed scales.

The suitability of using dissolved gases to determine groundwater discharge to high gradient streams

NASA Astrophysics Data System (ADS)

Gleeson, Tom; Manning, Andrew H.; Popp, Andrea; Zane, Matthew; Clark, Jordan F.

2018-02-01

Determining groundwater discharge to streams using dissolved gases is known to be useful over a wide range of streamflow rates but the suitability of dissolved gas methods to determine discharge rates in high gradient mountain streams has not been sufficiently tested, even though headwater streams are critical as ecological habitats and water resources. The aim of this study is to test the suitability of using dissolved gases to determine groundwater discharge rates to high gradient streams by field experiments in a well-characterized, high gradient mountain stream and a literature review. At a reach scale (550 m) we combined stream and groundwater radon activity measurements with an in-stream SF6 tracer test. By means of numerical modeling we determined gas exchange velocities and derived very low groundwater discharge rates (∼15% of streamflow). These groundwater discharge rates are below the uncertainty range of physical streamflow measurements and consistent with temperature, specific conductance and streamflow measured at multiple locations along the reach. At a watershed-scale (4 km), we measured CFC-12 and δ18O concentrations and determined gas exchange velocities and groundwater discharge rates with the same numerical model. The groundwater discharge rates along the 4 km stream reach were highly variable, but were consistent with the values derived in the detailed study reach. Additionally, we synthesized literature values of gas exchange velocities for different stream gradients which show an empirical relationship that will be valuable in planning future dissolved gas studies on streams with various gradients. In sum, we show that multiple dissolved gas tracers can be used to determine groundwater discharge to high gradient mountain streams from reach to watershed scales.

Quantifying uncertainty in discharge measurements: A new approach

USGS Publications Warehouse

Kiang, J.E.; Cohn, T.A.; Mason, R.R.

2009-01-01

The accuracy of discharge measurements using velocity meters and the velocity-area method is typically assessed based on empirical studies that may not correspond to conditions encountered in practice. In this paper, a statistical approach for assessing uncertainty based on interpolated variance estimation (IVE) is introduced. The IVE method quantifies all sources of random uncertainty in the measured data. This paper presents results employing data from sites where substantial over-sampling allowed for the comparison of IVE-estimated uncertainty and observed variability among repeated measurements. These results suggest that the IVE approach can provide approximate estimates of measurement uncertainty. The use of IVE to estimate the uncertainty of a discharge measurement would provide the hydrographer an immediate determination of uncertainty and help determine whether there is a need for additional sampling in problematic river cross sections. ?? 2009 ASCE.

Study of nitrogen flowing afterglow with mercury vapor injection

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

Mazánková, V., E-mail: mazankova@fch.vutbr.cz; Krčma, F.; Trunec, D.

2014-10-21

The reaction kinetics in nitrogen flowing afterglow with mercury vapor addition was studied by optical emission spectroscopy. The DC flowing post-discharge in pure nitrogen was created in a quartz tube at the total gas pressure of 1000 Pa and discharge power of 130 W. The mercury vapors were added into the afterglow at the distance of 30 cm behind the active discharge. The optical emission spectra were measured along the flow tube. Three nitrogen spectral systems – the first positive, the second positive, and the first negative, and after the mercury vapor addition also the mercury resonance line at 254more » nm in the spectrum of the second order were identified. The measurement of the spatial dependence of mercury line intensity showed very slow decay of its intensity and the decay rate did not depend on the mercury concentration. In order to explain this behavior, a kinetic model for the reaction in afterglow was developed. This model showed that the state Hg(6 {sup 3}P{sub 1}), which is the upper state of mercury UV resonance line at 254 nm, is produced by the excitation transfer from nitrogen N{sub 2}(A{sup 3}Σ{sup +}{sub u}) metastables to mercury atoms. However, the N{sub 2}(A{sup 3}Σ{sup +}{sub u}) metastables are also produced by the reactions following the N atom recombination, and this limits the decay of N{sub 2}(A{sup 3}Σ{sup +}{sub u}) metastable concentration and results in very slow decay of mercury resonance line intensity. It was found that N atoms are the most important particles in this late nitrogen afterglow, their volume recombination starts a chain of reactions which produce excited states of molecular nitrogen. In order to explain the decrease of N atom concentration, it was also necessary to include the surface recombination of N atoms to the model. The surface recombination was considered as a first order reaction and wall recombination probability γ = (1.35 ± 0.04) × 10{sup −6} was determined from the experimental data. Also

a Thermally Desorbable Miniature Passive Dosimeter for Organic Vapors

NASA Astrophysics Data System (ADS)

Gonzalez, Jesus Antonio

A thermally desorbable miniature passive dosimeter (MPD) for organic vapors has been developed in conformity with theoretical and practical aspects of passive dosimeter design. The device was optimized for low sample loadings resulting from short-term and/or low concentration level exposure. This was accomplished by the use of thermal desorption rather than solvent elution, which provided the GC method with significantly higher sensitivity. Laboratory evaluation of this device for factors critical to the performance of passive dosimeters using benzene as the test vapor included: desorption efficiency (97.2%), capacity (1400 ppm-min), sensitivity (7ng/sample or 0.06 ppmv for 15 minutes sampling) accuracy and precision, concentration level, environmental conditions (i.e., air face velocity, relative humidity) and sample stability during short (15 minutes) and long periods of time (15 days). This device has demonstrated that its overall accuracy meets NIOSH and OSHA requirements for a sampling and analytical method for the exposure concentration range of 0.1 to 50 ppm (v/v) and 15 minutes exposures. It was demonstrated that the MPD operates in accordance with theoretically predicted performance and should be adequate for short-term and/or low concentration exposure monitoring of organic vapors in the workplace. In addition a dynamic vapor exposure evaluation system for passive dosimeters have been validated using benzene as the test vapor. The system is capable of generating well defined short-square wave concentration profiles suitable for the evaluation of passive dosimeters for ceiling exposure monitoring.

Propellant Vaporization as a Criterion for Rocket-Engine Design; Experimental Performance, Vaporization and Heat-Transfer Rates with Various Propellant Combinations

NASA Technical Reports Server (NTRS)

Clark, Bruce J.; Hersch, Martin; Priem, Richard J.

1959-01-01

Experimental combustion efficiencies of eleven propellant combinations were determined as a function of chamber length. Efficiencies were measured in terms of characteristic exhaust velocities at three chamber lengths and in terms of gas velocities. The data were obtained in a nominal 200-pound-thrust rocket engine. Injector and engine configurations were kept essentially the same to allow comparison of the performance. The data, except for those on hydrazine and ammonia-fluorine, agreed with predicted results based on the assumption that vaporization of the propellants determines the rate of combustion. Decomposition in the liquid phase may be.responsible for the anomalous behavior of hydrazine. Over-all heat-transfer rates were also measured for each combination. These rates were close to the values predicted by standard heat-transfer calculations except for the combinations using ammonia.

Determination of discharge during pulsating flow

USGS Publications Warehouse

Thompson, T.H.

1968-01-01

Pulsating flow in an open channel is a manifestation of unstable-flow conditions in which a series of translatory waves of perceptible magnitude develops and moves rapidly downstream. Pulsating flow is a matter of concern in the design and operation of steep-gradient channels. If it should occur at high stages in a channel designed for stable flow, the capacity of the channel may be inadequate at a discharge that is much smaller than that for which the channel was designed. If the overriding translatory wave carries an appreciable part of the total flow, conventional stream-gaging procedures cannot be used to determine the discharge; neither the conventional instrumentation nor conventional methodology is adequate. A method of determining the discharge during pulsating flow was tested in the Santa Anita Wash flood control channel in Arcadia, Calif., April 16, 1965. Observations of the dimensions and velocities of translatory waves were made during a period of controlled reservoir releases of about 100, 200, and 300 cfs (cubic feet per second). The method of computing discharge was based on (1) computation of the discharge in the overriding waves and (2) computation of the discharge in the shallow-depth, or overrun, part of the flow. Satisfactory results were obtained by this method. However, the procedure used-separating the flow into two components and then treating the shallow-depth component as though it were steady--has no theoretical basis. It is simply an expedient for use until laboratory investigation can provide a satisfactory analytical solution to the problem of computing discharge during pulsating flow. Sixteen months prior to the test in Santa Anita Wash, a robot camera had been designed .and programmed to obtain the data needed to compute discharge by the method described above. The photographic equipment had been installed in Haines Creek flood control channel in Los Angeles, Calif., but it had not been completely tested because of the infrequency of

Energy distribution functions of kilovolt ions in a modified Penning discharge.

NASA Technical Reports Server (NTRS)

Roth, J. R.

1973-01-01

The distribution function of ion energy parallel to the magnetic field of a modified Penning discharge has been measured with a retarding potential energy analyzer. These ions escaped through one of the throats of the magnetic mirror geometry. Simultaneous measurements of the ion energy distribution function perpendicular to the magnetic field have been made with a charge-exchange neutral detector. The ion energy distribution functions are approximately Maxwellian, and the parallel and perpendicular kinetic temperatures are equal within experimental error. These results suggest that turbulent processes previously observed in this discharge Maxwellianize the velocity distribution along a radius in velocity space, and result in an isotropic energy distribution.

Energy distribution functions of kilovolt ions in a modified Penning discharge.

NASA Technical Reports Server (NTRS)

Roth, J. R.

1972-01-01

The distribution function of ion energy parallel to the magnetic field of a modified Penning discharge has been measured with a retarding potential energy analyzer. These ions escaped through one of the throats of the magnetic mirror geometry. Simultaneous measurements of the ion energy distribution function perpendicular to the magnetic field have been made with a charge-exchange neutral detector. The ion energy distribution functions are approximately Maxwellian, and the parallel and perpendicular kinetic temperatures are equal within experimental error. These results suggest that turbulent processes previously observed in this discharge Maxwellianize the velocity distribution along a radius in velocity space, and result in an isotropic energy distribution.

Alfven's critical ionization velocity observed in high power impulse magnetron sputtering discharges

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

Brenning, N.; Lundin, D.

2012-09-15

Azimuthally rotating dense plasma structures, spokes, have recently been detected in several high power impulse magnetron sputtering (HiPIMS) devices used for thin film deposition and surface treatment, and are thought to be important for plasma buildup, energizing of electrons, as well as cross-B transport of charged particles. In this work, the drift velocities of these spokes are shown to be strongly correlated with the critical ionization velocity, CIV, proposed by Alfven. It is proposed as the most promising approach in combining the CIV and HiPIMS research fields is to focus on the role of spokes in the process of electronmore » energization.« less

Equilibrium theory of cylindrical discharges with special application to helicons

NASA Astrophysics Data System (ADS)

Curreli, Davide; Chen, Francis F.

2011-11-01

Radiofrequency discharges used in industry often have centrally peaked plasma density profiles n(r) although ionization is localized at the edge, even in the presence of a dc magnetic field. This can be explained with a simple cylindrical model in one dimension as long as the short-circuit effect at the endplates causes a Maxwellian electron distribution. Surprisingly, a universal profile can be obtained, which is self-similar for all discharges with uniform electron temperature Te and neutral density nn. When all collisions and ionizations are radially accounted for, the ion drift velocity toward the wall reaches the Bohm velocity at a radius which can be identified with the sheath edge, thus obviating a pre-sheath calculation. For non-uniform Te and nn, the profiles change slightly but are always peaked on axis. For helicon discharges, iteration with the HELIC code for antenna-wave coupling yields profiles consistent with both energy deposition and diffusion profiles. Calculated density is in absolute-value agreement with experiment.

Plasma rotation by electric and magnetic fields in a discharge cylinder

NASA Technical Reports Server (NTRS)

Wilhelm, H. E.; Hong, S. H.

1977-01-01

A theoretical model for an electric discharge consisting of a spatially diverging plasma sustained electrically between a small ring cathode and a larger ring anode in a cylindrical chamber with an axial magnetic field is developed to study the rotation of the discharge plasma in the crossed electric and magnetic fields. The associated boundary-value problem for the coupled partial differential equations which describe the electric potential and the plasma velocity fields is solved in closed form. The electric field, current density, and velocity distributions are discussed in terms of the Hartmann number and the Hall coefficient. As a result of Lorentz forces, the plasma rotates with speeds as high as 1 million cm/sec around its axis of symmetry at typical conditions. As an application, it is noted that rotating discharges of this type could be used to develop a high-density plasma-ultracentrifuge driven by j x B forces, in which the lighter (heavier) ion and atom components would be enriched in (off) the center of the discharge cylinder.

ESTIMATING FLOW AND FLUX OF GROUND-WATER DISCHARGE USING WATER TEMPERATURE AND VELOCITY. (R827961)

EPA Science Inventory

The nature of ground water discharge to a stream has important implications for nearby ground water flow, especially with respect to contaminant transport and well-head protection. Measurements of ground water discharge were accomplished in this study using (1) differences bet...

Accidental Turbulent Discharge Rate Estimation from Videos

NASA Astrophysics Data System (ADS)

Ibarra, Eric; Shaffer, Franklin; Savaş, Ömer

2015-11-01

A technique to estimate the volumetric discharge rate in accidental oil releases using high speed video streams is described. The essence of the method is similar to PIV processing, however the cross correlation is carried out on the visible features of the efflux, which are usually turbulent, opaque and immiscible. The key step in the process is to perform a pixelwise time filtering on the video stream, in which the parameters are commensurate with the scales of the large eddies. The velocity field extracted from the shell of visible features is then used to construct an approximate velocity profile within the discharge. The technique has been tested on laboratory experiments using both water and oil jets at Re ~105 . The technique is accurate to 20%, which is sufficient for initial responders to deploy adequate resources for containment. The software package requires minimal user input and is intended for deployment on an ROV in the field. Supported by DOI via NETL.

Flow determination of a pump-turbine at zero discharge

NASA Astrophysics Data System (ADS)

Edinger, G.; Erne, S.; Doujak, E.; Bauer, C.

2014-03-01

When starting up a reversible Francis pump-turbine in pump mode, the machine may operate at zero flow at a given gate opening. Besides reversal flow and prerotation in the draft tube cone, the onset of a fully separated flow in the vaned diffuser is observable at zero- discharge condition. In this paper, the occurrence of prerotation and reversal flow in the conical draft tube and the flow in one stay vane channel of a pump-turbine are examined experimentally and compared to numerical simulations. In order to assess the strongly three-dimensional flow in the stay vane channel, measurements with a 2D laser doppler velocimeter (LDV) were performed at various positions. The inlet flow in the draft tube cone, which becomes significantly at zero discharge in pump mode, is investigated by velocity measurements at two different positions. Pressure fluctuations in the draft tube cone induced by complex flow patterns are also recorded and analyzed. It is found that the swirl number at zero discharge does not significant differ from the values obtained at very low load pumping. Experimental investigations combined with CFD have shown that in the stay vane channel flow velocity components different from zero occur even at no discharge. Streamline plots show the fully separated flow structure.

Flow Injection Photochemical Vapor Generation Coupled with Miniaturized Solution-Cathode Glow Discharge Atomic Emission Spectrometry for Determination and Speciation Analysis of Mercury.

PubMed

Mo, Jiamei; Li, Qing; Guo, Xiaohong; Zhang, Guoxia; Wang, Zheng

2017-10-03

A novel, compact, and green method was developed for the determination and speciation analysis of mercury, based on flow injection photochemical vapor generation (PVG) coupled with miniaturized solution cathode glow discharge-atomic emission spectroscopy (SCGD-AES). The SCGD was generated between a miniature hollow titanium tube and a solution emerging from a glass capillary. Cold mercury vapor (Hg(0)) was generated by PVG and subsequently delivered to the SCGD for excitation, and finally the emission signals were recorded by a miniaturized spectrograph. The detection limits (DLs) of Hg(II) and methylmercury (MeHg) were both determined to be 0.2 μg L -1 . Moreover, mercury speciation analysis could also be performed by using different wavelengths and powers from the UV lamp and irradiation times. Both Hg(II) and MeHg can be converted to Hg(0) for the determination of total mercury (T-Hg) with 8 W/254 nm UV lamp and 60 s irradiation time; while only Hg(II) can be reduced to Hg(0) and determined selectively with 4 W/365 nm UV lamp and 20 s irradiation time. Then, the concentration of MeHg can be calculated by subtracting the Hg(II) from the T-Hg. Because of its similar sensitivity and DL at 8 W/254 nm, the simpler and less toxic Hg(II) was used successfully as a primary standard for the quantification of T-Hg. The novel PVG-SCGD-AES system provides not only a 365-fold improvement in the DL for Hg(II) but also a nonchromatographic method for the speciation analysis of mercury. After validating its accuracy, this method was successfully used for mercury speciation analysis of water and biological samples.

Applications of remote sensing to stream discharge predictions

NASA Technical Reports Server (NTRS)

Krause, F. R.; Winn, C. B.

1972-01-01

A feasibility study has been initiated on the use of remote earth observations for augmenting stream discharge prediction for the design and/or operation of major reservoir systems, pumping systems and irrigation systems. The near-term objectives are the interpolation of sparsely instrumented precipitation surveillance networks and the direct measurement of water loss by evaporation. The first steps of the study covered a survey of existing reservoir systems, stream discharge prediction methods, gage networks and the development of a self-adaptive variation of the Kentucky Watershed model, SNOPSET, that includes snowmelt. As a result of these studies, a special three channel scanner is being built for a small aircraft, which should provide snow, temperature and water vapor maps for the spatial and temporal interpolation of stream gages.

Three-dimensional kinetic and fluid dynamic modeling and three iterative algorithms for side-pumped alkali vapor lasers

NASA Astrophysics Data System (ADS)

Shen, Binglin; Xu, Xingqi; Xia, Chunsheng; Pan, Bailiang

2017-11-01

Combining the kinetic and fluid dynamic processes in static and flowing-gas diode-pumped alkali vapor lasers, a comprehensive physical model with three cyclically iterative algorithms for simulating the three-dimensional pump and laser intensities as well as temperature distribution in the vapor cell of side-pumped alkali vapor lasers is established. Comparison with measurement of a static side-pumped cesium vapor laser with a diffuse type hollow cylinder cavity, and with classical and modified models is made. Influences of flowed velocity and pump power on laser power are calculated and analyzed. The results have demonstrated that for high-power side-pumped alkali vapor lasers, it is necessary to take into account the three-dimensional distributions of pump energy, laser energy and temperature in the cell to simultaneously obtain the thermal features and output characteristics. Therefore, the model can deepen the understanding of the complete kinetic and fluid dynamic mechanisms of a side-pumped alkali vapor laser, and help with its further experimental design.

Interfacial nonequilibrium and Bénard-Marangoni instability of a liquid-vapor system

NASA Astrophysics Data System (ADS)

Margerit, J.; Colinet, P.; Lebon, G.; Iorio, C. S.; Legros, J. C.

2003-10-01

We study Bénard-Marangoni instability in a system formed by a horizontal liquid layer and its overlying vapor. The liquid is lying on a hot rigid plate and the vapor is bounded by a cold parallel plate. A pump maintains a reduced pressure in the vapor layer and evacuates the vapor. This investigation is undertaken within the classical quasisteady approximation for both the vapor and the liquid phases. The two layers are separated by a deformable interface. Temporarily frozen temperature and velocity distributions are employed at each instant for the stability analysis, limited to infinitesimal disturbances (linear regime). We use irreversible thermodynamics to model the phase change under interfacial nonequilibrium. Within this description, the interface appears as a barrier for transport of both heat and mass. Hence, in contrast with previous studies, we consider the possibility of a temperature jump across the interface, as recently measured experimentally. The stability analysis shows that the interfacial resistances to heat and mass transfer have a destabilizing influence compared to an interface that is in thermodynamic equilibrium. The role of the fluctuations in the vapor phase on the onset of instability is discussed. The conditions to reduce the system to a one phase model are also established. Finally, the influence of the evaporation parameters and of the presence of an inert gas on the marginal stability curves is discussed.

Piston pump and method of reducing vapor lock

DOEpatents

Phillips, Benjamin A.; Harvey, Michael N.

2000-02-15

A pump includes a housing defining a cavity, at least one bore, a bore inlet, and a bore outlet. The bore extends from the cavity to the outlet and the inlet communicates with the bore at a position between the cavity and the outlet. A crankshaft is mounted in supports and has an eccentric portion disposed in the cavity. The eccentric portion is coupled to a piston so that rotation of the crankshaft reciprocates the piston in the bore between a discharge position an intake position. The bore may be offset from an axis of rotation to reduce bending of the piston during crankshaft rotation. During assembly of the pump, separate parts of the housing can be connected together to facilitate installation of internal pumping components. Also disclosed is a method of reducing vapor lock by mixing vapor and liquid portions of a substance and introducing the mixture into a piston bore.

Piston pump and method of reducing vapor lock

DOEpatents

Phillips, Benjamin A.; Harvey, Michael N.

2001-01-30

A pump includes a housing defining a cavity, at least one bore, a bore inlet, and a bore outlet. The bore extends from the cavity to the outlet and the inlet communicates with the bore at a position between the cavity and the outlet. A crankshaft is mounted in supports and has an eccentric portion disposed in the cavity. The eccentric portion is coupled to a piston so that rotation of the crankshaft reciprocates the piston in the bore between a discharge position an intake position. The bore may be offset from an axis of rotation to reduce bending of the piston during crankshaft rotation. During assembly of the pump, separate parts of the housing can be connected together to facilitate installation of internal pumping components. Also disclosed is a method of reducing vapor lock by mixing vapor and liquid portions of a substance and introducing the mixture into a piston bore.

Star of Condor - A strontium critical velocity experiment, Peru, 1983

NASA Technical Reports Server (NTRS)

Wescott, E. M.; Stenbaek-Nielsen, H. C.; Hallinan, T.; Foeppl, H.; Valenzuela, A.

1986-01-01

'Star of Condor' was a critical velocity experiment using Sr vapor produced in a radial shaped charge, which was carried to 571.11 km altitude on a Taurus-Tomahawk rocket launched from Punto Lobos, Peru, and detonated in the plane of the magnetic field lines so that all ranges of pitch angles from parallel to B to perpendicular to B were covered. Sr has a critical velocity of 3.3 km/s, and from observation, 42.5 percent of the neutral Sr gas had a velocity component perpendicular to B exceeding that value. No Sr ion emissions were detected shortly after the burst with usual TV integration times. However, about 10 min after the detonation a faint field-aligned streak was discovered with long TV integration times. The brightness is estimated as 5 R, which, combined with the streak geometry, implies an ion production of 2.4 x 10 to the 19th ions. This is only 0.0036 percent ionization of the Sr vapor. All the ions could easily have been produced by thermal ionization from the original detonation thermal distribution. The breakup of the Sr gas into small bloblike structures may have allowed the high-energy electrons to escape before an ionization cascade could be produced. For whatever reason, the Alfven mechanism proposed for space plasmas in the absence of laboratory walls did not produce an ionization cascade in the experiment.

Neutral gas rotation in magnetron discharge

NASA Astrophysics Data System (ADS)

Pal, A. F.; Ryabinkin, A. N.; Serov, A. O.; Filippov, A. V.

2014-12-01

We have experimentally established the existence and determined the velocity of motion of the neutral component of plasma in a planar magnetron discharge, which takes place in the direction of drift of the charged plasma component in crossed electric and magnetic ( E × B) fields. For this purpose, we have studied the propagation of a small gaseous additive over the plasma ring of dc magnetron discharge in the diffusion regime. The obtained temporal dependences of the intensity of atomic emission spectra of the additive in various regions of the plasma ring are compared to the results of numerical solution of the diffusion equation for the experimental conditions studied.

Measurement of OH Radicals in Pulsed Corona and Pulsed Dielectric Barrier Discharge

NASA Astrophysics Data System (ADS)

Ono, Ryo; Oda, Tetsuji

OH radicals are measured in a pulsed corona or a pulsed dielectric barrier discharge (DBD) using laserinduced fluorescence (LIF) method. The pulsed discharges occur in nitrogen-oxygen mixture with 2.4% water vapor at atmospheric pressure. The pulse width is 100ns and the peak voltage is 35kV. The electrode configuration is a needle to plate electrode with 16-mm gap for corona discharge, and with 5-mm gap for DBD where the barrier is 2mm thick glass plate. It is shown that OH density is approximately proportional to the energy consumed by the discharge. The OH density per the discharge energy is about 2-4×1014cm-3/mJ for both discharges in H2O(2.4%)/N2 mixture. It is shown that OH density increases with oxygen content in DBD, whereas OH density reaches a maximum at 3% oxygen content in corona discharge. The existence of oxygen accelerates OH decay rate in both discharges. A trace amount of trichloroethylene (TCE) is added to the ambient gas. It is shown that the addition of 100ppm TCE to corona discharge reduces discharge current by about 50%. That leads to decrease of OH production.

Are the argon metastables important in high power impulse magnetron sputtering discharges?

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

Gudmundsson, J. T., E-mail: tumi@hi.is; Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik; Lundin, D.

2015-11-15

We use an ionization region model to explore the ionization processes in the high power impulse magnetron sputtering (HiPIMS) discharge in argon with a titanium target. In conventional dc magnetron sputtering (dcMS), stepwise ionization can be an important route for ionization of the argon gas. However, in the HiPIMS discharge stepwise ionization is found to be negligible during the breakdown phase of the HiPIMS pulse and becomes significant (but never dominating) only later in the pulse. For the sputtered species, Penning ionization can be a significant ionization mechanism in the dcMS discharges, while in the HiPIMS discharge Penning ionization ismore » always negligible as compared to electron impact ionization. The main reasons for these differences are a higher plasma density in the HiPIMS discharge, and a higher electron temperature. Furthermore, we explore the ionization fraction and the ionized flux fraction of the sputtered vapor and compare with recent experimental work.« less

Quantification of vapor intrusion pathways into a slab-on-ground building under varying environmental conditions.

PubMed

Patterson, Bradley M; Davis, Greg B

2009-02-01

Potential hydrocarbon-vapor intrusion pathways into a building through a concrete slab-on-ground were investigated and quantified under a variety of environmental conditions to elucidate the potential mechanisms for indoor air contamination. Vapor discharge from the uncovered open ground soil adjacent to the building and subsequent advection into the building was unlikely due to the low soil-gas concentrations at the edge of the building as a result of aerobic biodegradation of hydrocarbon vapors. When the building's interior was under ambient pressure, a flux of vapors into the building due to molecular diffusion of vapors through the building's concrete slab (cyclohexane 11 and methylcyclohexane 31 mg m(-2) concrete slab day(-1)) and short-term (up to 8 h) cyclical pressure-driven advection of vapors through an artificial crack (cyclohexane 4.2 x 10(3) and methylcyclohexane 1.2 x 10(4) mg m(-2) cracks day(-1)) was observed. The average subslab vapor concentration under the center of the building was 25,000 microg L(-1). Based on the measured building's interiorvapor concentrations and the building's air exchange rate of 0.66 h(-1), diffusion of vapors through the concrete slab was the dominantvapor intrusion pathway and cyclical pressure exchanges resulted in a near zero advective flux. When the building's interior was under a reduced pressure (-12 Pa), advective transport through cracks or gaps in the concrete slab (cyclohexane 340 and methylcyclohexane 1100 mg m(-2) cracks day(-1)) was the dominant vapor intrusion pathway.

Dynamics of ozone and OH radicals generated by pulsed corona discharge in humid-air flow reactor measured by laser spectroscopy

NASA Astrophysics Data System (ADS)

Ono, Ryo; Oda, Tetsuji

2003-05-01

The dynamics of ozone and OH radicals are studied in pulsed corona discharge plasma in a humid-air environment. Ozone density is measured by the laser absorption method, and OH density is measured by the laser-induced fluorescence (LIF) method. A 100-ns pulsed corona discharge occurs between a series of 25 needle electrodes and a plate electrode. After the pulsed discharge, the time evolutions of ozone and OH densities are measured in humid air or a humid nitrogen-oxygen mixture. Results show that the addition of 2.4% water vapor to dry air reduces ozone production by a factor of about 6, and shortens the ozone formation time constant from 30 to 6 μs. Water vapor may reduce atomic oxygen levels leading to the decreased production of ozone by O+O2 reaction. The LIF measurement for OH radicals shows that OH density is approximately constant for 10 μs after the pulsed discharge, then decays by recombination reaction and reactions with the discharge products of oxygen, such as ozone or atomic oxygen. Absolute OH density is estimated; it is about 3×1015 cm-3 in streamers at 10 μs after discharge in the H2O(2.4%)/N2 mixture.

Observation of hydroxymethyl hydroperoxide in a reaction system containing CH{sub 2}OO and water vapor through pure rotational spectroscopy

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

Nakajima, Masakazu; Endo, Yasuki, E-mail: endo@bunshi.c.u-tokyo.ac.jp

Pure rotational transitions of hydroxymethyl hydroperoxide (HMHP) were observed in the discharged plasma of a CH{sub 2}I{sub 2}/O{sub 2}/water gas mixture, where the water complex with the simplest Criegee intermediate CH{sub 2}OO has been identified [M. Nakajima and Y. Endo, J. Chem. Phys. 140, 134302 (2014)]. Isotope experiments using heavy water support that the currently observed HMHP molecule was produced by the reaction of CH{sub 2}OO with water vapor. The observed species was identified as the most stable conformer with the help of quantum chemical calculations. We also clarified that productions of formic acid and dioxirane are promoted by themore » existence of water vapor in the discharged reaction system.« less

Discharge measurements at gaging stations

USGS Publications Warehouse

Turnipseed, D. Phil; Sauer, Vernon B.

2010-01-01

The techniques and standards for making discharge measurements at streamflow gaging stations are described in this publication. The vertical axis rotating-element current meter, principally the Price current meter, has been traditionally used for most measurements of discharge; however, advancements in acoustic technology have led to important developments in the use of acoustic Doppler current profilers, acoustic Doppler velocimeters, and other emerging technologies for the measurement of discharge. These new instruments, based on acoustic Doppler theory, have the advantage of no moving parts, and in the case of the acoustic Doppler current profiler, quickly and easily provide three-dimensional stream-velocity profile data through much of the vertical water column. For much of the discussion of acoustic Doppler current profiler moving-boat methodology, the reader is referred to U.S. Geological Survey Techniques and Methods 3-A22 (Mueller and Wagner, 2009). Personal digital assistants (PDAs), electronic field notebooks, and other personal computers provide fast and efficient data-collection methods that are more error-free than traditional hand methods. The use of portable weirs and flumes, floats, volumetric tanks, indirect methods, and tracers in measuring discharge are briefly described.

Discharge characteristics of embankment-shaped weirs

USGS Publications Warehouse

Kindsvater, Carl E.

1964-01-01

An embankment-shaped weir is an embankment overtopped by flood waters. Among the engineering problems frequently resulting from. this occurrence is the need to compute the peak discharge from postflood yield observations. The research described in this. report was concerned with the theoretical and experimental bases for the computation procedure. The research had two main objectives. One was to determine the relationship between embankment form and roughness and some of the more important discharge characteristics. The second was to define, theoretically and experimentally, the relationship between free-flow discharge and the boundary layer on the roadway. The first objective was accomplished with the experimental determination of coefficients of discharge and other significant flow characteristics for a variety of boundary and flow conditions. The second objective was accomplished with the development and experimental verification of a discharge equation which involved the boundary layer displacement thickness. This phase of the research included a general investigation of boundary layer growth on the roadway. It is included that both free- and submerged-flow discharge are virtually independent of the influence of embankment shape and relative height. The influence of boundary resistance is appreciable only for smaller heads. The most practical solution for discharge is one which is based on. the simple weir equation and experimentally determined coefficients. A completely analytical equation of discharge is impractical. The report contains the results of 936 experiments on the discharge characteristics of 17 different models; plus 106 boundary-layer velocity traverses on 4 different models. The data are summarized in both graphical and tabular form.

Oxidation and Volatilization of Silica-Formers in Water Vapor

NASA Technical Reports Server (NTRS)

Opila, E. J.; Gray, Hugh R. (Technical Monitor)

2002-01-01

At high temperatures SiC and Si3N4 react with water vapor to form a silica scale. Silica scales also react with water vapor to form a volatile Si(OH)4 species. These simultaneous reactions, one forming silica and the other removing silica, are described by paralinear kinetics. A steady state, in which these reactions occur at the same rate, is eventually achieved, After steady state is achieved, the oxide found on the surface is a constant thickness and recession of the underlying material occurs at a linear rate. The steady state oxide thickness, the time to achieve steady state, and the steady state recession rate can all be described in terms of the rate constants for the oxidation and volatilization reactions. In addition, the oxide thickness, the time to achieve steady state, and the recession rate can also be determined from parameters that describe a water vapor-containing environment. Accordingly, maps have been developed to show these steady state conditions as a function of reaction rate constants, pressure, and gas velocity. These maps can be used to predict the behavior of silica formers in water-vapor containing environments such as combustion environments. Finally, these maps are used to explore the limits of the paralinear oxidation model for SiC and Si3N4

Comparison of bottom-track to global positioning system referenced discharges measured using an acoustic Doppler current profiler

USGS Publications Warehouse

Wagner, Chad R.; Mueller, David S.

2011-01-01

A negative bias in discharge measurements made with an acoustic Doppler current profiler (ADCP) can be caused by the movement of sediment on or near the streambed. The integration of a global positioning system (GPS) to track the movement of the ADCP can be used to avoid the systematic negative bias associated with a moving streambed. More than 500 discharge transects from 63 discharge measurements with GPS data were collected at sites throughout the US, Canada, and New Zealand with no moving bed to compare GPS and bottom-track-referenced discharges. Although the data indicated some statistical bias depending on site conditions and type of GPS data used, these biases were typically about 0.5% or less. An assessment of differential correction sources was limited by a lack of data collected in a range of different correction sources and different GPS receivers at the same sites. Despite this limitation, the data indicate that the use of Wide Area Augmentation System (WAAS) corrected positional data is acceptable for discharge measurements using GGA as the boat-velocity reference. The discharge data based on GPS-referenced boat velocities from the VTG data string, which does not require differential correction, were comparable to the discharges based on GPS-referenced boat velocities from the differentially-corrected GGA data string. Spatial variability of measure discharges referenced to GGA, VTG and bottom-tracking is higher near the channel banks. The spatial variability of VTG-referenced discharges is correlated with the spatial distribution of maximum Horizontal Dilution of Precision (HDOP) values and the spatial variability of GGA-referenced discharges is correlated with proximity to channel banks.

Vapor plume oscillation mechanisms in transient keyhole during tandem dual beam fiber laser welding

NASA Astrophysics Data System (ADS)

Chen, Xin; Zhang, Xiaosi; Pang, Shengyong; Hu, Renzhi; Xiao, Jianzhong

2018-01-01

Vapor plume oscillations are common physical phenomena that have an important influence on the welding process in dual beam laser welding. However, until now, the oscillation mechanisms of vapor plumes remain unclear. This is primarily because mesoscale vapor plume dynamics inside a millimeter-scale, invisible, and time-dependent keyhole are difficult to quantitatively observe. In this paper, based on a developed three-dimensional (3D) comprehensive model, the vapor plume evolutions in a dynamical keyhole are directly simulated in tandem dual beam, short-wavelength laser welding. Combined with the vapor plume behaviors outside the keyhole observed by high-speed imaging, the vapor plume oscillations in dynamical keyholes at different inter-beam distances are the first, to our knowledge, to be quantitatively analyzed. It is found that vapor plume oscillations outside the keyhole mainly result from vapor plume instabilities inside the keyhole. The ejection velocity at the keyhole opening and dynamical behaviors outside the keyhole of a vapor plume both violently oscillate with the same order of magnitude of high frequency (several kHz). Furthermore, the ejection speed at the keyhole opening and ejection area outside the keyhole both decrease as the beam distance increases, while the degree of vapor plume instability first decreases and then increases with increasing beam distance from 0.6 to 1.0 mm. Moreover, the oscillation mechanisms of a vapor plume inside the dynamical keyhole irradiated by dual laser beams are investigated by thoroughly analyzing the vapor plume occurrence and flow process. The vapor plume oscillations in the dynamical keyhole are found to mainly result from violent local evaporations and severe keyhole geometry variations. In short, the quantitative method and these findings can serve as a reference for further understanding of the physical mechanisms in dual beam laser welding and of processing optimizations in industrial applications.

Dynamics of laser-guided alternating current high voltage discharges

NASA Astrophysics Data System (ADS)

Daigle, J.-F.; Théberge, F.; Lassonde, P.; Kieffer, J.-C.; Fujii, T.; Fortin, J.; Châteauneuf, M.; Dubois, J.

2013-10-01

The dynamics of laser-guided alternating current high voltage discharges are characterized using a streak camera. Laser filaments were used to trigger and guide the discharges produced by a commercial Tesla coil. The streaking images revealed that the dynamics of the guided alternating current high voltage corona are different from that of a direct current source. The measured effective corona velocity and the absence of leader streamers confirmed that it evolves in a pure leader regime.

Ion mobility spectrometric analysis of vaporous chemical warfare agents by the instrument with corona discharge ionization ammonia dopant ambient temperature operation.

PubMed

Satoh, Takafumi; Kishi, Shintaro; Nagashima, Hisayuki; Tachikawa, Masumi; Kanamori-Kataoka, Mieko; Nakagawa, Takao; Kitagawa, Nobuyoshi; Tokita, Kenichi; Yamamoto, Soichiro; Seto, Yasuo

2015-03-20

The ion mobility behavior of nineteen chemical warfare agents (7 nerve gases, 5 blister agents, 2 lachrymators, 2 blood agents, 3 choking agents) and related compounds including simulants (8 agents) and organic solvents (39) was comparably investigated by the ion mobility spectrometry instrument utilizing weak electric field linear drift tube with corona discharge ionization, ammonia doping, purified inner air drift flow circulation operated at ambient temperature and pressure. Three alkyl methylphosphonofluoridates, tabun, and four organophosphorus simulants gave the intense characteristic positive monomer-derived ion peaks and small dimer-derived ion peaks, and the later ion peaks were increased with the vapor concentrations. VX, RVX and tabun gave both characteristic positive monomer-derived ions and degradation product ions. Nitrogen mustards gave the intense characteristic positive ion peaks, and in addition distinctive negative ion peak appeared from HN3. Mustard gas, lewisite 1, o-chlorobenzylidenemalononitrile and 2-mercaptoethanol gave the characteristic negative ion peaks. Methylphosphonyl difluoride, 2-chloroacetophenone and 1,4-thioxane gave the characteristic ion peaks both in the positive and negative ion mode. 2-Chloroethylethylsulfide and allylisothiocyanate gave weak ion peaks. The marker ion peaks derived from two blood agents and three choking agents were very close to the reactant ion peak in negative ion mode and the respective reduced ion mobility was fluctuated. The reduced ion mobility of the CWA monomer-derived peaks were positively correlated with molecular masses among structurally similar agents such as G-type nerve gases and organophosphorus simulants; V-type nerve gases and nitrogen mustards. The slope values of the calibration plots of the peak heights of the characteristic marker ions versus the vapor concentrations are related to the detection sensitivity, and within chemical warfare agents examined the slope values for sarin, soman

Biofiltration of solvent vapors from air

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

Oh, Young-sook.

1993-01-01

For various industrial solvent vapors, biofiltration promises to offer a cost-effective emission control technology. Exploiting the full potential of this technology will help attain the goals of the Clean Air Act Amendments of 1990. Concentrating on large volumes of volatile industrial solvents, stable multicomponent microbial enrichments capable of growing a mineral medium with solvent vapors as their only source of carbon and energy were obtained from soil and sewage sludge. These consortia were immobilized on an optimized porous solid support (ground peat moss and perlite). The biofilter material was packed in glass columns connected to an array of pumps andmore » flow meters that allowed the independent variation of superficial velocity and solvent vapor concentrations. In various experiments, single solvents, such as methanol, butanol, acetonitrile, hexane and nitrobenzene, and solvent mixtures, such as benzene-toluene-xylene (BTX) and chlorobenzene-o-dichlorobenzene (CB/DCB) were biofiltered with rates ranging from 15 to334 g solvent removed per m[sup 3] filter volume /h. Pressure drops were low to moderate (0-10 mmHg/m) and with periodic replacement of moisture, the biofiltration activity could be maintained for a period of several months. The experimental data on methanol biofiltration were subjected to mathematical analysis and modeling by the group of Dr. Baltzis at NJIT for a better understanding and a possible scale up of solvent vapor biofilters. In the case of chlorobenzenes and nitrobenzene, the biofilter columns had to be operated with water recirculation in a trickling filter mode. To prevent inactivation of the trickling filter by acidity during CB/DCB removal, pH control was necessary, and the removal rate of CB/DCB was strongly influenced by the flow rate of the recyling water. Nitrobenzene removal in a trickling filter did not require pH control, since the nitro group was reduced and volatilized as ammonia.« less

Comparative characteristics of electron energy spectrum in PIG and arc type discharge plasmas

NASA Technical Reports Server (NTRS)

Romanyuk, L. I.; Suavilnyy, N. Y.

1978-01-01

The electron distribution functions relative to the velocity component directed along the magnetic field are compared for PIG and arc type discharges. The identity of these functions for the plasma region pierced by the primary electron beam and their difference in the peripheral part of the discharge are shown. It is concluded that the electron distribution function in the PIG type discharge is formed during one transit of the primary electron through the discharge gap. The mechanisms of electron energy spectrum formation in both the axis region and the peripheral region of the discharge are discussed.

Dependence of electron peak current on hollow cathode dimensions and seed electron energy in a pseudospark discharge

NASA Astrophysics Data System (ADS)

Cetiner, S. O.; Stoltz, P.; Messmer, P.; Cambier, J.-L.

2008-01-01

The prebreakdown and breakdown phases of a pseudospark discharge are investigated using the two-dimensional kinetic plasma simulation code OOPIC™ PRO. Trends in the peak electron current at the anode are presented as function of the hollow cathode dimensions and mean seed injection velocities at the cavity back wall. The plasma generation process by ionizing collisions is examined, showing the effect on supplying the electrons that determine the density of the beam. The mean seed velocities used here are varied between the velocity corresponding to the energy of peak ionization cross section, 15 times this value and no mean velocity (i.e., electrons injected with a temperature of 2.5eV). The reliance of the discharge characteristics on the penetrating electric field is shown to decrease as the mean seed injection velocity increases because of its ability to generate a surplus plasma independent of the virtual anode. As a result, the peak current increases with the hollow cathode dimensions for the largest average injection velocity, while for the smallest value it increases with the area of penetration of the electric field in the hollow cathode interior. Additionally, for a given geometry an increase in the peak current with the surplus plasma generated is observed. For the largest seed injection velocity used a dependence of the magnitude of the peak current on the ratio of the hole thickness and hollow cathode depth to the hole height is demonstrated. This means similar trends of the peak current are generated when the geometry is resized. Although the present study uses argon only, the variation in the discharge dependencies with the seed injection energy relative to the ionization threshold is expected to apply independently of the gas type. Secondary electrons due to electron and ion impact are shown to be important only for the largest impact areas and discharge development times of the study.

Measurement of discharge using tracers

USGS Publications Warehouse

Kilpatrick, Frederick A.; Cobb, Ernest D.

1984-01-01

The development of fluorescent dyes and fluorometers that can measure these dyes at very low concentrations has made dye-dilution methods practical for measuring discharge. These methods are particularly useful for determining discharge under certain flow conditions that are unfavorable for current meter measurements. These include small streams, canals, and pipes where:Turbulence is excessive for current meter measurement but conducive to good mixing.Moving rocks and debris are damaging to any instruments placed in the flow.Cross-sectional areas or velocities are indeterminant or changing.There are some unsteady flows such as exist with storm-runoff events on small streams.The flow is physically inaccessible or unsafe.From a practical standpoint, such measurements are limited primarily to small streams due to excessively long channel mixing lengths required of larger streams. Very good accuracy can be obtained provided:Adequate mixing length and time are allowed.Careful field and laboratory techniques are employed.Dye losses are not significant.This manual describes the slug-injection and constant-rate injection methods of performing tracer-dilution measurements. Emphasis is on the use of fluorescent dyes as tracers and the equipment, field methods, and Laboratory procedures for performing such measurements. The tracer-velocity method is also briefly discussed.

Observations of Water Vapor Outflow from NML Cygnus

NASA Astrophysics Data System (ADS)

Zubko, Viktor; Li, Di; Lim, Tanya; Feuchtgruber, Helmut; Harwit, Martin

2004-07-01

We report new observations of the far-infrared and submillimeter water vapor emission of NML Cygnus based on data gathered with the Infrared Space Observatory and the Submillimeter Wave Astronomy Satellite. We compare the emission from NML Cyg to that previously published for VY CMa and W Hya in an attempt to establish the validity of recently proposed models for the outflow from evolved stars. The data obtained support the contention by Ivezić & Elitzur that the atmospheres of evolved stars obey a set of scaling laws in which the optical depth of the outflow is the single most significant scaling parameter, affecting both the radiative transfer and the dynamics of the outflow. Specifically, we provide observations comparing the water vapor emission from NML Cyg, VY CMa, and W Hya and find, to the extent permitted by the quality of our data, that the results are in reasonable agreement with a model developed by Zubko & Elitzur. Using this model we derive a mass loss based on the dust opacities, spectral line fluxes, and outflow velocities of water vapor observed in the atmospheres of these oxygen-rich giants. For VY CMa and NML Cyg, we also obtain an estimate of the stellar mass.

Comparison of the surface dielectric barrier discharge characteristics under different electrode gaps

NASA Astrophysics Data System (ADS)

Gao, Guoqiang; Dong, Lei; Peng, Kaisheng; Wei, Wenfu; Li, Chunmao; Wu, Guangning

2017-01-01

Currently, great interests are paid to the surface dielectric barrier discharge due to the diverse and interesting application. In this paper, the influences of the electrode gap on the discharge characteristics have been studied. Aspects of the electrical parameters, the optical emission, and the discharge induced gas flow were considered. The electrode gap varied from 0 mm to 21 mm, while the applied AC voltage was studied in the range of 17 kV-27 kV. Results indicate that with the increase of the electrode gap, the variation of discharge voltage exhibits an increasing trend, while the other parameters (i.e., the current, power, and induced flow velocity) increase first, and then decrease once the gap exceeded the critical value. Mechanisms of the electrode gap influencing these key parameters were discussed from the point of equivalent circuit. The experimental results reveal that an optimal discharge gap can be obtained, which is closely related to the applied voltage. Visualization of the induced flow with different electrode gaps was realized by the Schlieren diagnostic technique. Finally, the velocities of induced gas flow determined by the pitot tube were compared with the results of intensity-integral method, and good agreements were found.

Kinetics of the Active Medium of a Copper Vapor Brightness Amplifier

NASA Astrophysics Data System (ADS)

Kulagin, A. E.; Torgaev, S. N.; Evtushenko, G. S.; Trigub, M. V.

2018-03-01

A spatiotemporal kinetics of the active medium of a copper vapor brightness amplifier is described that allows gain characteristics to be investigated during the pump pulse. Model calculations show that changing the discharge parameters allows the radial gain profiles to be improved significantly, as well as the gain and the inversion duration to be increased. The data obtained will be used to choose the operating conditions for the active medium in the brightness amplifier mode.

Influence of residual plasma drift velocity on the post-arc sheath expansion of vacuum circuit breakers

NASA Astrophysics Data System (ADS)

Mo, Yongpeng; Shi, Zongqian; Bai, Zhibin; Jia, Shenli; Wang, Lijun

2016-05-01

The residual plasma in the inter-contact region of a vacuum circuit breaker moves towards the post-arc cathode at current zero, because the residual plasma mainly comes from the cathode spots during the arc burning process. In the most previous theoretical researches on the post-arc sheath expansion process of vacuum circuit breakers, only the thermal motion of residual plasma was taken into consideration. Alternately, the residual plasma was even assumed to be static at the moment of current zero in some simplified models. However, the influence of residual plasma drift velocity at current zero on the post-arc sheath expansion process was rarely investigated. In this paper, this effect is investigated by a one-dimensional particle-in-cell model. Simulation results indicate that the sheath expands slower with higher residual plasma drift velocity in the initial sheath expansion stage. However, with the increase of residual plasma drift velocity, the overall plasma density in the inter-contact region decreases faster, and the sheath expansion velocity increases earlier. Consequently, as a whole, it needs shorter time to expel the residual plasma from the inter-contact region. Furthermore, if the residual plasma drift velocity is high enough, the sheath expansion process ceases before it develops to the post-arc anode. Besides, the influence of the collisions between charges and neutrals is investigated as well in terms of the density of metal vapor. It shows that the residual plasma drift velocity takes remarkable effect only if the density of the metal vapor is relatively low, which corresponds to the circumstance of low-current interruptions.

A new test chamber to measure material emissions under controlled air velocity

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

Bortoli, M. de; Ghezzi, E.; Knoeppel, H.

1999-05-15

A new 20-L glass chamber for the determination of VOC emissions from construction materials and consumer products under controlled air velocity and turbulence is described. Profiles of air velocity and turbulence, obtained with precisely positioned hot wire anemometric probes, show that the velocity field is homogeneous and that air velocity is tightly controlled by the fan rotation speed; this overcomes the problem of selecting representative positions to measure air velocity above a test specimen. First tests on material emissions show that the influence of air velocity on the emission rate of VOCs is negligible for sources limited by internal diffusionmore » and strong for sources limited by evaporation. In a velocity interval from 0.15 to 0.30 m s{sup {minus}1}, an emission rate increase of 50% has been observed for pure n-decane and 1,4-dichlorobenzene and of 30% for 1,2-propanediol from a water-based paint. In contrast, no measurable influence of turbulence could be observed during vaporization of 1,4-dichlorobenzene within a 3-fold turbulence interval. Investigations still underway show that the chamber has a high recovery for the heavier VOC (TXIB), even at low concentrations.« less

Spoke rotation reversal in magnetron discharges of aluminium, chromium and titanium

NASA Astrophysics Data System (ADS)

Hecimovic, A.; Maszl, C.; Schulz-von der Gathen, V.; Böke, M.; von Keudell, A.

2016-06-01

The rotation of localised ionisation zones, i.e. spokes, in magnetron discharge are frequently observed. The spokes are investigated by measuring floating potential oscillations with 12 flat probes placed azimuthally around a planar circular magnetron. The 12-probe setup provides sufficient temporal and spatial resolution to observe the properties of various spokes, such as rotation direction, mode number and angular velocity. The spokes are investigated as a function of discharge current, ranging from 10 mA (current density 0.5 mA cm-2) to 140 A (7 A cm-2). In the range from 10 mA to 600 mA the plasma was sustained in DC mode, and in the range from 1 A to 140 A the plasma was pulsed in high-power impulse magnetron sputtering mode. The presence of spokes throughout the complete discharge current range indicates that the spokes are an intrinsic property of a magnetron sputtering plasma discharge. The spokes may disappear at discharge currents above 80 A for Cr, as the plasma becomes homogeneously distributed over the racetrack. Up to discharge currents of several amperes (the exact value depends on the target material), the spokes rotate in a retrograde \\mathbf{E}× \\mathbf{B} direction with angular velocity in the range of 0.2-4 km s-1. Beyond a discharge current of several amperes, the spokes rotate in a \\mathbf{E}× \\mathbf{B} direction with angular velocity in the range of 5-15 km s-1. The spoke rotation reversal is explained by a transition from Ar-dominated to metal-dominated sputtering that shifts the plasma emission zone closer to the target. The spoke itself corresponds to a region of high electron density and therefore to a hump in the electrical potential. The electric field around the spoke dominates the spoke rotation direction. At low power, the plasma is further away from the target and it is dominated by the electric field to the anode, thus retrograde \\mathbf{E}× \\mathbf{B} rotation. At high power, the plasma is closer to the target and it is

Dynamics of vapor plume in transient keyhole during laser welding of stainless steel: Local evaporation, plume swing and gas entrapment into porosity

NASA Astrophysics Data System (ADS)

Pang, Shengyong; Chen, Xin; Shao, Xinyu; Gong, Shuili; Xiao, Jianzhong

2016-07-01

In order to better understand the local evaporation phenomena of keyhole wall, vapor plume swing above the keyhole and ambient gas entrapment into the porosity defects, the 3D time-dependent dynamics of the metallic vapor plume in a transient keyhole during fiber laser welding is numerically investigated. The vapor dynamical parameters, including the velocity and pressure, are successfully predicted and obtain good agreements with the experimental and literature data. It is found that the vapor plume flow inside the keyhole has complex multiple directions, and this various directions characteristic of the vapor plume is resulted from the dynamic evaporation phenomena with variable locations and orientations on the keyhole wall. The results also demonstrate that because of this dynamic local evaporation, the ejected vapor plume from the keyhole opening is usually in high frequency swinging. The results further indicate that the oscillation frequency of the plume swing angle is around 2.0-8.0 kHz, which is of the same order of magnitude with that of the keyhole depth (2.0-5.0 kHz). This consistency clearly shows that the swing of the ejected vapor plume is closely associated with the keyhole instability during laser welding. Furthermore, it is learned that there is usually a negative pressure region (several hundred Pa lower than the atmospheric pressure) of the vapor flow around the keyhole opening. This pressure could lead to a strong vortex flow near the rear keyhole wall, especially when the velocity of the ejected metallic vapor from the keyhole opening is high. Under the effect of this flow, the ambient gas is involved into the keyhole, and could finally be entrapped into the bubbles within a very short time (<0.2 ms) due to the complex flow inside the keyhole.

Degree of vaporization using an airblast type injector for a premixed-prevaporized combustor

NASA Technical Reports Server (NTRS)

Tacina, R. R.

1978-01-01

Vaporization data that could be useful in designing premixed-prevaporized fuel preparation systems for gas turbine combustors are presented. The effect of the experimental parameters on vaporization was found to be E = T sub in tau 0.18 (V sub ref + 38) (P sub in + 35)/203000 where E is the degree of vaporization in percent, T sub in the inlet air temperature in K over the range 450 to 700 K, the residence time in ms over the range 4.3 to 23.8 ms, V sub ref the reference velocity in m/s over the range 5 to 22 m/s, and P sub in the inlet pressure in MPa over the range 0.18 to 0.59 MPa. Jet A and Diesel no. 2 fuels were tested for the effect of inlet air temperature and were found to have nearly identical results.

Numerical Modeling of Pulsed Electrical Discharges for High-Speed Flow Control

DTIC Science & Technology

2012-02-01

dimensions , and later on more complex problems. Subsequent work compared different physical models for pulsed discharges: one-moment (drift-diffusion with...two dimensions , and later on more complex problems. Subsequent work compared different physical models for pulsed discharges: one-moment (drift...The state of a particle can be specified by its position and velocity. In principal, the motion of a large group of particles can be predicted from

Practical Experience of Discharge Measurement in Flood Conditions with ADP

NASA Astrophysics Data System (ADS)

Vidmar, A.; Brilly, M.; Rusjan, S.

2009-04-01

Accurate discharge estimation is important for an efficient river basin management and especially for flood forecasting. The traditional way of estimating the discharge in hydrological practice is to measure the water stage and to convert the recorded water stage values into discharge by using the single-valued rating curve .Relationship between the stage and discharge values of the rating curve for the extreme events are usually extrapolated by using different mathematical methods and are not directly measured. Our practice shows that by using the Accoustic Doppler Profiler (ADP) instrument we can record the actual relation between the water stage and the flow velocity at the occurrence of flood waves very successfully. Measurement in flood conditions it is not easy task, because of high water surface velocity and large amounts of sediments in the water and floating objects on the surface like branches, bushes, trees, piles and others which can also easily damage ADP instrument. We made several measurements in such extreme events on the Sava River down to the nuclear power plant Kr\\vsko where we have install fixed cable way. During the several measurement with traditional "moving-boat" measurement technique a mowing bed phenomenon was clearly seen. Measuring flow accurately using ADP that uses the "moving-boat" technique, the system needs a reference against which to relate water velocities to. This reference is river bed and must not move. During flood events we detected difficulty finding a static bed surface to which to relate water velocities. This is caused by motion of the surface layer of bed material or also sediments suspended in the water near bed very densely. So these traditional »moving-boat« measurement techniques that we normally use completely fail. Using stationary measurement method to making individual velocity profile measurements, using an Acoustic Doppler Profiler (ADP), at certain time at fixed locations across the width of a stream gave

Simulation of the early startup period of high-temperature heat pipes from the frozen state by a rarefied vapor self-diffusion model

NASA Technical Reports Server (NTRS)

Cao, Y.; Faghri, A.

1993-01-01

The heat pipe startup process is described physically and is divided into five periods for convenience of analysis. The literature survey revealed that none of the previous attempts to simulate the heat pipe startup process numerically were successful, since the rarefied vapor flow in the heat pipe was not considered. Therefore, a rarefied vapor self-diffusion model is proposed, and the early startup periods, in which the rarefied vapor flow is dominant within the heat pipe, are first simulated numerically. The numerical results show that large vapor density gradients existed along the heat pipe length, and the vapor flow reaches supersonic velocities when the density is extremely low. The numerical results are compared with the experimental data of the early startup period with good agreement.

Error estimates for ice discharge calculated using the flux gate approach

NASA Astrophysics Data System (ADS)

Navarro, F. J.; Sánchez Gámez, P.

2017-12-01

Ice discharge to the ocean is usually estimated using the flux gate approach, in which ice flux is calculated through predefined flux gates close to the marine glacier front. However, published results usually lack a proper error estimate. In the flux calculation, both errors in cross-sectional area and errors in velocity are relevant. While for estimating the errors in velocity there are well-established procedures, the calculation of the error in the cross-sectional area requires the availability of ground penetrating radar (GPR) profiles transverse to the ice-flow direction. In this contribution, we use IceBridge operation GPR profiles collected in Ellesmere and Devon Islands, Nunavut, Canada, to compare the cross-sectional areas estimated using various approaches with the cross-sections estimated from GPR ice-thickness data. These error estimates are combined with those for ice-velocities calculated from Sentinel-1 SAR data, to get the error in ice discharge. Our preliminary results suggest, regarding area, that the parabolic cross-section approaches perform better than the quartic ones, which tend to overestimate the cross-sectional area for flight lines close to the central flowline. Furthermore, the results show that regional ice-discharge estimates made using parabolic approaches provide reasonable results, but estimates for individual glaciers can have large errors, up to 20% in cross-sectional area.

Eddy correlation measurements of submarine groundwater discharge

USGS Publications Warehouse

Crusius, John; Berg, P.; Koopmans, D.J.; Erban, L.

2008-01-01

This paper presents a new, non-invasive means of quantifying groundwater discharge into marine waters using an eddy correlation approach. The method takes advantage of the fact that, in virtually all aquatic environments, the dominant mode of vertical transport near the sediment–water interface is turbulent mixing. The technique thus relies on measuring simultaneously the fluctuating vertical velocity using an acoustic Doppler velocimeter and the fluctuating salinity and/or temperature using rapid-response conductivity and/or temperature sensors. The measurements are typically done at a height of 5–15 cm above the sediment surface, at a frequency of 16 to 64 Hz, and for a period of 15 to 60 min. If the groundwater salinity and/or temperature differ from that of the water column, the groundwater specific discharge (cm d− 1) can be quantified from either a heat or salt balance. Groundwater discharge was estimated with this new approach in Salt Pond, a small estuary on Cape Cod (MA, USA). Estimates agreed well with previous estimates of discharge measured using seepage meters and 222Rn as a tracer. The eddy correlation technique has several desirable characteristics: 1) discharge is quantified under in-situ hydrodynamic conditions; 2) salinity and temperature can serve as two semi-independent tracers of discharge; 3) discharge can be quantified at high temporal resolution, and 4) long-term records of discharge may be possible, due to the low power requirements of the instrumentation.

Atmospheric pressure argon surface discharges propagated in long tubes: physical characterization and application to bio-decontamination

NASA Astrophysics Data System (ADS)

Kovalova, Zuzana; Leroy, Magali; Jacobs, Carolyn; Kirkpatrick, Michael J.; Machala, Zdenko; Lopes, Filipa; Laux, Christophe O.; DuBow, Michael S.; Odic, Emmanuel

2015-11-01

Pulsed corona discharges propagated in argon (or in argon with added water vapor) at atmospheric pressure on the interior surface of a 49 cm long quartz tube were investigated for the application of surface bio-decontamination. H2O molecule dissociation in the argon plasma generated reactive species (i.e. OH in ground and excited states) and UV emission, which both directly affected bacterial cells. In order to facilitate the evaluation of the contribution of UV radiation, a DNA damage repair defective bacterial strain, Escherichia coli DH-1, was used. Discharge characteristics, including propagation velocity and plasma temperature, were measured. Up to ~5.5 and ~5 log10 reductions were observed for E. coli DH-1 bacteria (from 106 initial load) exposed 2 cm and 44 cm away from the charged electrode, respectively, for a 20 min plasma treatment. The factors contributing to the observed bactericidal effect include desiccation, reactive oxygen species (OH) plus H2O2 accumulation in the liquid phase, and UV-B (and possibly VUV) emission in dry argon. The steady state temperature measured on the quartz tube wall did not exceeded 29 °C the contribution of heating, along with that of H2O2 accumulation, was estimated to be low. The effect of UV-B emission alone or in combination with the other stress factors of the plasma process was examined for different operating conditions.

Calibrated vapor generator source

DOEpatents

Davies, John P.; Larson, Ronald A.; Goodrich, Lorenzo D.; Hall, Harold J.; Stoddard, Billy D.; Davis, Sean G.; Kaser, Timothy G.; Conrad, Frank J.

1995-01-01

A portable vapor generator is disclosed that can provide a controlled source of chemical vapors, such as, narcotic or explosive vapors. This source can be used to test and calibrate various types of vapor detection systems by providing a known amount of vapors to the system. The vapor generator is calibrated using a reference ion mobility spectrometer. A method of providing this vapor is described, as follows: explosive or narcotic is deposited on quartz wool, placed in a chamber that can be heated or cooled (depending on the vapor pressure of the material) to control the concentration of vapors in the reservoir. A controlled flow of air is pulsed over the quartz wool releasing a preset quantity of vapors at the outlet.

Calibrated vapor generator source

DOEpatents

Davies, J.P.; Larson, R.A.; Goodrich, L.D.; Hall, H.J.; Stoddard, B.D.; Davis, S.G.; Kaser, T.G.; Conrad, F.J.

1995-09-26

A portable vapor generator is disclosed that can provide a controlled source of chemical vapors, such as, narcotic or explosive vapors. This source can be used to test and calibrate various types of vapor detection systems by providing a known amount of vapors to the system. The vapor generator is calibrated using a reference ion mobility spectrometer. A method of providing this vapor is described, as follows: explosive or narcotic is deposited on quartz wool, placed in a chamber that can be heated or cooled (depending on the vapor pressure of the material) to control the concentration of vapors in the reservoir. A controlled flow of air is pulsed over the quartz wool releasing a preset quantity of vapors at the outlet. 10 figs.

VAPOR PRESSURES AND HEATS OF VAPORIZATION OF PRIMARY COAL TARS

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

Eric M. Suuberg; Vahur Oja

1997-07-01

This project had as its main focus the determination of vapor pressures of coal pyrolysis tars. It involved performing measurements of these vapor pressures and from them, developing vapor pressure correlations suitable for use in advanced pyrolysis models (those models which explicitly account for mass transport limitations). This report is divided into five main chapters. Each chapter is a relatively stand-alone section. Chapter A reviews the general nature of coal tars and gives a summary of existing vapor pressure correlations for coal tars and model compounds. Chapter B summarizes the main experimental approaches for coal tar preparation and characterization whichmore » have been used throughout the project. Chapter C is concerned with the selection of the model compounds for coal pyrolysis tars and reviews the data available to us on the vapor pressures of high boiling point aromatic compounds. This chapter also deals with the question of identifying factors that govern the vapor pressures of coal tar model materials and their mixtures. Chapter D covers the vapor pressures and heats of vaporization of primary cellulose tars. Chapter E discusses the results of the main focus of this study. In summary, this work provides improved understanding of the volatility of coal and cellulose pyrolysis tars. It has resulted in new experimentally verified vapor pressure correlations for use in pyrolysis models. Further research on this topic should aim at developing general vapor pressure correlations for all coal tars, based on their molecular weight together with certain specific chemical characteristics i.e. hydroxyl group content.« less

On the theoretical velocity distribution and flow resistance in natural channels

NASA Astrophysics Data System (ADS)

Moramarco, Tommaso; Dingman, S. Lawrence

2017-12-01

The velocity distribution in natural channels is of considerable interest for streamflow measurements to obtain information on discharge and flow resistance. This study focuses on the comparison of theoretical velocity distributions based on 1) entropy theory, and 2) the two-parameter power law. The analysis identifies the correlation between the parameters of the distributions and defines their dependence on the geometric and hydraulic characteristics of the channel. Specifically, we investigate how the parameters are related to the flow resistance in terms of Manning roughness, shear velocity and water surface slope, and several formulae showing their relationships are proposed. Velocity measurements carried out in the past 20 years at Ponte Nuovo gauged section along the Tiber River, central Italy, are the basis for the analysis.

Expansion of effective wet bulb globe temperature for vapor impermeable protective clothing.

PubMed

Sakoi, Tomonori; Mochida, Tohru; Kurazumi, Yoshihito; Sawada, Shin-Ichi; Horiba, Yosuke; Kuwabara, Kohei

2018-01-01

The wet bulb globe temperature (WBGT) is an effective measure for risk screening to prevent heat dISOrders. However, a heat risk evaluation by WBGT requires adjustments depending on the clothing. In this study, we proposed a new effective WBGT (WBGT eff * ) for general vapor permeable clothing ensembles and vapor impermeable protective clothing that is applicable to occupants engaged in moderate intensity work with a metabolic heat production value of around 174W/m 2 . WBGT eff * enables the conversion of heat stress into the scale experienced by the occupant dressed in the basic clothing ensemble (work clothes) based on the heat balances for a human body. We confirmed that WBGT eff * was effective for expressing the critical thermal environments for the prescriptive zones for occupants wearing vapor impermeable protective clothing. Based on WBGT eff * , we succeeded in clarifying how the weights for natural wet bulb, globe, and air temperatures and the intercept changed depending on clothing properties and the surrounding environmental factors when heat stress is expressed by the weighted sum of natural wet bulb, globe, and air temperatures and the intercept. The weight of environmental temperatures (globe and air temperatures) for WBGT eff * for vapor impermeable protective clothing increased compared with that for general vapor permeable clothing, whereas that of the natural wet bulb temperature decreased. For WBGT eff * in outdoor conditions with a solar load, the weighting ratio of globe temperature increased and that of air temperature decreased with air velocity. Approximation equations of WBGT eff * were proposed for both general vapor permeable clothing ensembles and for vapor impermeable protective clothing. Copyright © 2017 Elsevier Ltd. All rights reserved.

Observations of precipitable water vapor fluctuations in convective boundary layer via microwave interferometry

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

Shao, X.M.; Carlos, R.C.; Kirkland, M.W.

1999-07-01

At microwave frequencies, each centimeter of precipitable water vapor (PWV) causes about 6.45 cm of extra electrical path length relative to the {open_quotes}dry{close_quotes} air. The fluctuations of the water vapor dominate the changes of the effective path length through the atmosphere in a relatively short time period of a few hours. In this paper we describe a microwave interferometer developed for water vapor investigations and present the observation results. The interferometer consists of 10 antennas along two orthogonal 400-m arms that form many baselines (antenna pairs) ranging from 100 to 400 m. All the antennas receive a common CW signalmore » (11.7 GHz) from a geostationary television satellite, and phase differences between pairs of antennas are measured. The phase differences reflect the column-integrated water vapor differences from the top of the atmosphere to the spatially separated antennas at the ground. The interferometric, baseline-differential measurements allow us to study the statistical properties of the PWV fluctuations, as well as the turbulent activity of the convective boundary layer (CBL). Structure function analysis of the interferometer measurements shows good agreement with results obtained from the Very Large Array (VLA) and with a theoretical model developed for radio astronomical very long baseline interferometry (VLBI), reported previously by other investigators. The diurnally varying structure constant correlates remarkably well with the combination of the latent and sensible heat fluxes measured simultaneously from a 10-m meteorological tower. The average drift velocity of the PWV over the interferometer was also derived from the measurements. The derived velocity agrees well during the morning hours with the wind measured by an anemometer at the center of the interferometer. {copyright} 1999 American Geophysical Union« less

Photoselective vaporization of the prostate: the basel experience after 108 procedures.

PubMed

Bachmann, Alexander; Ruszat, Robin; Wyler, Stephen; Reich, Oliver; Seifert, Helge H; Müller, Alexander; Sulser, Tullio

2005-06-01

This study aims to investigate safety and efficacy of 80 watt high-power potassium titanyl phosphate (KTP) laser vaporization of the prostate in men with lower urinary tract symptoms (LUTS) secondary to benign prostatic hyperplasia (BPH). 108 patients underwent 80W KTP laser vaporization. Functional follow-up included measurement of maximum urinary flow rate (Qmax), postvoid residual volume (Vres) and International Prostate Symptom Score (IPSS) within a 12 months period. The average prostate volume was 52.2+/-24.3 ml and the preoperative PSA value was 3.6+/-3.6 ng/dl. Mean operation time was 54.5+/-25.0 min. Qmax increased highly significantly (p<0.001) by 111% (+7.9 ml/s) at discharge, 212% (+15.1 ml/s) after three months, 201% (+14.3 ml/s) after six months and 252% (+17.9 ml/s) after 12 months. Correspondingly, Vres, IPSS and Bother Score improved to an extent that was statistically highly significant (p<0.001) immediately after surgery. The observed complication rate within one year was low. 80 W KTP laser vaporization is a virtually bloodless, safe and effective procedure for surgical treatment of LUTS secondary to BPH. A significant improvement of objective and subjective voiding parameters was observed just after surgery. KTP laser vaporization is associated with a low rate of complications.

Kinetics and Chemistry of Ionization Wave Discharges Propagating Over Dielectric Surfaces

NASA Astrophysics Data System (ADS)

Petrishchev, Vitaly

Experimental studies of near-surface ionization wave electric discharges generated by high peak voltage (20-30 kV), nanosecond duration pulses (full width at half-maximum 50-100 ns) of positive and negative polarity and propagating over dielectric surfaces have been performed. A novel way to sustain diffuse, reproducible, ns pulse surface plasmas at a liquid-vapor interface is demonstrated at buffer gas pressures ranging from 10 to 200 Torr. Generation of surface ionization waves well reproduced shot-to-shot and sustaining diffuse near-surface plasmas is one of the principal advantages of the use of ns pulse discharge waveforms. This makes possible characterization of these plasmas in repetitively pulsed experiments. Numerous applications of these plasmas include low-temperature plasma assisted combustion, plasma fuel reforming, plasma flow control, plasma materials processing, agriculture, biology, and medicine. The objectives of the present work are (i) to demonstrate that surface ionization wave discharge plasmas sustained at a liquid-vapor interface can be used as an experimental platform for studies of near-surface plasma chemical reaction kinetics, at the conditions when the interface acts as a high-yield source of radical species, and (ii) to obtain quantitative insight into dynamics, kinetics and chemistry of surface ionization wave discharges and provide experimental data for validation of kinetic models, to assess their predictive capability. Generation of the initial radical pool may trigger a number of plasma chemical processes leading to formation of a variety of stable product species, depending on the initial composition of the liquid and the buffer gas flow. One of the products formed and detected during surface plasma / liquid water interaction is hydroxyl radical, which is closely relevant to applications of plasmas for biology and medicine. The present work includes detailed studies of surface ionization wave discharges sustained in different

Enthalpy of Vaporization and Vapor Pressures: An Inexpensive Apparatus

ERIC Educational Resources Information Center

Battino, Rubin; Dolson, David A.; Hall, Michael A.; Letcher, Trevor M.

2007-01-01

A simple and inexpensive method to determine the enthalpy of vaporization of liquids by measuring vapor pressure as a function of temperature is described. The vapor pressures measured with the stopcock cell were higher than the literature values and those measured with the sidearm rubber septum cell were both higher and lower than literature…

Investigation of heavy current discharges with high initial gas density

NASA Astrophysics Data System (ADS)

Budin, A.; Bogomaz, A.; Kolikov, V.; Kuprin, A.; Leontiev, V.; Rutberg, Ph.; Shirokov, N.

1996-05-01

Piezoelectric pressure transducers, with noise immunity and time resolution of 0,5 μs were used to measure pulse pressures of 430 MPa along the axis of an electrical discharge channel. Initial concentration of He was 2,7ṡ1021cm-3, dI/dt=6ṡ1011 A/s, and Imax=560 kA. Shock waves with amplitudes exceeding the pressure along the axis, were detected by a pressure transducer on the wall of the discharge chamber. Typical shock velocities were 2ṡ4 km/s. Average pressure measurements along the discharge axis at different radii were used to estimate the current density distribution along the canal radius. The presence of the shock waves, promoting the additional hydrogen heating in the discharge chamber, has been registered during the discharge in hydrogen for Imax˜1 MA and an initial concentration of 1021cm-3.

Measurement of discharge using tracers

USGS Publications Warehouse

Kilpatrick, F.A.; Cobb, Ernest D.

1985-01-01

The development of fluorescent dyes and fluorometers that can measure these dyes at very low concentrations has made dye-dilution methods practical for measuring discharge. These methods are particularly useful for determining discharge under certain flow conditions that are unfavorable for current meter measurements. These include small streams, canals, and pipes where 1. Turbulence is excessive for current-meter measurement but conducive to good mixing. 2. Moving rocks and debris may damage instruments placed in the flow. 3. Cross-sectional areas or velocities are indeterminate or changing. 4. The flow is unsteady, such as the flow that exists with storm-runoff events on small streams and urban storm-sewer systems. 5. The flow is physically inaccessible or unsafe. From a practical standpoint, such methods are limited primarily to small streams, because of the excessively long channel-mixing lengths required for larger streams. Very good accuracy can be obtained provided that 1. Adequate mixing length and time are allowed. 2. Careful field and laboratory techniques are used. 3. Dye losses are not significant. This manual describes the slug-injection and constant-rate injection methods of performing tracer-dilution measurements. Emphasis is on the use of fluorescent dyes as tracers and the equipment, field methods, and laboratory procedures for performing such measurements. The tracer-velocity method is also briefly discussed.

Scavenging flow velocity in small two-strokes at high engine speed

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

Ekenberg, M.; Johansson, B.

1995-12-31

2D-LDV-measurements were made on the flow from one transfer channel into the cylinder in a small two-stroke SI engine. The LDV measuring volume was located just outside the transfer port. The engine was a carburetted piston-ported crankcase compression chainsaw engine and it was run with wide open throttle at 9000 RPM. The muffler was removed to enable access into the cylinder. No additional seeding was used; the fuel and/or oil was not entirely vaporized as it entered the cylinder. Very high velocities ({approximately}275 m/s) were detected in the beginning of the scavenging phase. The horizontal velocity was, during the wholemore » scavenging phase, higher than the vertical.« less

Vibrationally Excited Carbon Monoxide Produced via a Chemical Reaction Between Carbon Vapor and Oxygen

NASA Astrophysics Data System (ADS)

Jans, Elijah R.; Eckert, Zakari; Frederickson, Kraig; Rich, Bill; Adamovich, Igor V.

2017-06-01

Measurements of the vibrational distribution function of carbon monoxide produced via a reaction between carbon vapor and molecular oxygen has shown a total population inversion on vibrational levels 4-7. Carbon vapor, produced using an arc discharge to sublimate graphite, is mixed with an argon oxygen flow. The excited carbon monoxide is vibrationally populated up to level v=14, at low temperatures, T=400-450 K, in a collision-dominated environment, 15-20 Torr, with total population inversions between v=4-7. The average vibrational energy per CO molecule formed by the reaction is 0.6-1.2 eV/molecule, which corresponds to 10-20% of the reaction enthalpy. Kinetic modeling of the flow reactor, including state specific vibrational processes, was performed to infer the vibrational distribution of the products of the reaction. The results show viability of developing of a new chemical CO laser from the reaction of carbon vapor and oxygen.

Influence of residual plasma drift velocity on the post-arc sheath expansion of vacuum circuit breakers

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

Mo, Yongpeng; Shi, Zongqian; Jia, Shenli

The residual plasma in the inter-contact region of a vacuum circuit breaker moves towards the post-arc cathode at current zero, because the residual plasma mainly comes from the cathode spots during the arc burning process. In the most previous theoretical researches on the post-arc sheath expansion process of vacuum circuit breakers, only the thermal motion of residual plasma was taken into consideration. Alternately, the residual plasma was even assumed to be static at the moment of current zero in some simplified models. However, the influence of residual plasma drift velocity at current zero on the post-arc sheath expansion process wasmore » rarely investigated. In this paper, this effect is investigated by a one-dimensional particle-in-cell model. Simulation results indicate that the sheath expands slower with higher residual plasma drift velocity in the initial sheath expansion stage. However, with the increase of residual plasma drift velocity, the overall plasma density in the inter-contact region decreases faster, and the sheath expansion velocity increases earlier. Consequently, as a whole, it needs shorter time to expel the residual plasma from the inter-contact region. Furthermore, if the residual plasma drift velocity is high enough, the sheath expansion process ceases before it develops to the post-arc anode. Besides, the influence of the collisions between charges and neutrals is investigated as well in terms of the density of metal vapor. It shows that the residual plasma drift velocity takes remarkable effect only if the density of the metal vapor is relatively low, which corresponds to the circumstance of low-current interruptions.« less

Microspectroscopic imaging of solution plasma: How do its physical properties and chemical species evolve in atmospheric-pressure water vapor bubbles?

NASA Astrophysics Data System (ADS)

Yui, Hiroharu; Banno, Motohiro

2018-01-01

In this article, we review the development of scientific instruments for obtaining information on the evolution of physical properties and chemical species of solution plasma (SP). When a pulsed high voltage is applied between electrodes immersed in an aqueous solution, SP is formed in water vapor bubbles transiently generated in the solution under atmospheric pressure. To clarify how SP emerges in water vapor bubbles and is sustained in solutions, an instrument with micrometer spatial resolution and nanosecond temporal resolution is required. To meet these requirements, a microscopic system with a custom-made optical discharge cell was newly developed, where the working distance between the SP and the microscopic objective lens was minimized. A hollow electrode equipped in the discharge cell also enabled us to control the chemical composition in water vapor bubbles. To study the spatial and temporal evolutions of chemical species in micrometer and nano- to microsecond regions, a streak camera with a spectrometer and a CCD detector with a time-gated electronic device were combined with the microscope system. The developed instrument is expected to contribute to providing a new means of developing new schemes for chemical reactions and material syntheses.

Diffusive-convective physical vapor transport of PbTe from a Te-rich solid source

NASA Technical Reports Server (NTRS)

Zoutendyk, J.; Akutagawa, W.

1982-01-01

Crystal growth of PbTe by physical vapor transport (sublimation) in a closed ampoule is governed by the vapor species in thermal equilibrium with the solid compound. Deviations from stoichiometry in the source material cause diffusion limitation of the transport rate, which can be modified by natural (gravity-driven) convection. Mass-transport experiments have been performed using Te-rich material wherein sublimation rates have been measured in order to study the effects of natural convection in diffusion-limited vapor transport. Linear velocities for both crystal growth and evaporation (back sublimation) have been measured for transport in the direction of gravity, horizontally, and opposite to gravity. The experimental results are discussed in terms of both the one-dimensional diffusive-advective model and current, more sophisticated theory which includes natural convection. There is some evidence that convection effects from radial temperature gradients and solutal density gradients have been observed.

Bohm velocity in the presence of a hot cathode

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

Palacio Mizrahi, J. H.; Krasik, Ya. E.

2013-08-15

The spatial distribution of the plasma and beam electrons in a region whose extension from a hot cathode is larger than the Debye length, but smaller than the electron mean free path, is analyzed. In addition, the influence of electrons thermionically emitted from a hot cathode and the ratio of electron-to-ion mass on the Bohm velocity and on the ion and electron densities at the plasma-sheath boundary in a gas discharge are studied. It is shown that thermionic emission has the effect of increasing the Bohm velocity, and this effect is more pronounced for lighter ions. In addition, it ismore » shown that the Bohm velocity cannot be increased to more than 24% above its value when there is no electron emission.« less

Airborne microwave radar measurements of surface velocity in a tidally-driven inlet

NASA Astrophysics Data System (ADS)

Farquharson, G.; Thomson, J. M.

2012-12-01

A miniaturized dual-beam along-track interferometric (ATI) synthetic aperture radar (SAR), capable of measuring two components of surface velocity at high resolution, was operated during the 2012 Rivers and Inlets Experiment (RIVET) at the New River Inlet in North Carolina. The inlet is predominantly tidally-driven, with little upstream river discharge. Surface velocities in the inlet and nearshore region were measured during ebb and flood tides during a variety of wind and offshore wave conditions. The radar-derived surface velocities range from around ±2~m~s1 during times of maximum flow. We compare these radar-derived surface velocities with surface velocities measured with drifters. The accuracy of the radar-derived velocities is investigated, especially in areas of large velocity gradients where along-track interferometric SAR can show significant differences with surface velocity. The goal of this research is to characterize errors in along-track interferometric SAR velocity so that ATI SAR measurements can be coupled with data assimilative modeling with the goal of developing the capability to adequately constrain nearshore models using remote sensing measurements.

Petroleum Vapor Intrusion

EPA Pesticide Factsheets

One type of vapor intrusion is PVI, in which vapors from petroleum hydrocarbons such as gasoline, diesel, or jet fuel enter a building. Intrusion of contaminant vapors into indoor spaces is of concern.

Structure and properties of optical-discharge plasma in CO2-laser beam near target surface

NASA Astrophysics Data System (ADS)

Danshchikov, Ye. V.; Dymshakov, V. A.; Lebedev, F. V.; Ryazanov, A. V.

1986-05-01

An experimental study of optical-discharge plasma in a CO2-laser beam at a target surface was made for the purpose of exploring the not yet understood role of this plasma in the laser-target interaction process. Such a plasma was produced by means of a quasi-continuous CO2-laser with an unstable resonator, its power being maintained constant for 1 ms periods. Its radiation was focused on the surfaces of thick and seeding thin Al, Ti, and Ta targets inclined at an approximately 70 deg. angle to the beam, inside a hermetic chamber containing air, argon, or helium under atmospheric pressure. The radiation intensity distribution over the focal plane and the nearest caustic surface in the laser beam was measured along with the plasma parameters, the latter by the methods of spectral analysis and photoelectric recording. The instrumentation for this purpose included an MDR-3 monochromator with an entrance slit, a double electron-optical converter, a memory oscillograph, and an SI-10-30 ribbon lamp as radiation reference standard. The results yielded integral diametral intensity distributions of the emission lines Ti-II (457.2 nm), Ti-I (464 nm), Ar-II (462 nm), radial and axial temperature profiles of optical discharge in metal vapor in surrounding gas, and the radial temperature profile of irradiated metal surface at successive instants of time. The results reveal marked differences between the structures and the properties of optical-discharge plasma in metal vapor and in surrounding gas, optical discharge in the former being characterized by localization within the laser beam and optical discharge in the latter being characterized by a drift away from the target.

Short-term velocity measurements at Columbia Glacier, Alaska; August-September 1984

USGS Publications Warehouse

Vaughn, B.H.; Raymond, C.F.; Rasmussen, Lowell A.; Miller, D.S.; Michaelson, C.A.; Meier, M.F.; Krimmel, R.M.; Fountain, A.G.; Dunlap, W.W.; Brown, C.S.

1985-01-01

Ice velocity data are presented for the lower reach of Columbia Glacier, Alaska. The data span a 29 day period and contain 1,072 angle sightings from two survey stations to 22 markers placed on the ice surface, and 1,621 laser measurements of the distance to one of those markers (number 11) from another station. These short-interval observations were made to investigate the dynamics of the glacier and to provide input to models for estimation of future retreat and iceberg discharge. The mean ice velocity (at marker number 11) was approximately 9 m/day and ranged from 8 to < 15 m/day. The data set includes a well defined 2-day, 50% velocity increase and a clear pattern of velocity fluctuations of about 5% with approximately diurnal and semiurnal periods. (Author 's abstract)

A single surgeon's experience with contact laser vaporization of the prostate

NASA Astrophysics Data System (ADS)

Mueller, Edward J.

1995-05-01

Herein, I report on my first 50 contact laser prostatectomies performed with the SLT Nd:YAG laser. The obstructed prostatic urethra is opened via contact laser vaporization of the obstructing adenoma. The average pre-op AUA symptom score was 22.9 (range 14 - 30). The average 3 month post-op AUA symptom score was 2.1 (range 0 -8). Eighteen of the patients had the foley catheter removed approximately 4 - 6 hours post-op and were discharged the same day. Thirty patients had the foley catheter removed the morning following surgery and were discharged. And two patients had the foley catheter removed the morning following surgery, but remained in the hospital for medical reasons unrelated to the TURP. Thus, 48 (96%) of the patients were discharged within 24 hours of admission. No patient had to be readmitted to the hospital for any reason. All patients were allowed to return to full activity within 24 hours of discharge. The average hospital cost for the 48 patients discharged within 24 hours was DOL4,694. This compares to the average hospital cost of an electrocautery TURP of DOL6-8000. In summary, contact laser TURP using the SLT Nd:YAG laser relived the symptoms of an obstructing prostate comparable to electrocautery TURP. However, these results were achieved with a much shorter hospitalization, a quicker return to full activity and at a lower cost.

Modeling Peak Discharge within the Marengo River Watershed: Lessons for Restoration in the Saint Louis River Watershed

EPA Science Inventory

To more fully understand the hydrologic condition of the Marengo River Watershed, and to map specific locations most likely to have increased discharge and flow velocity (leading to more erosion and higher sediment loads) we modeled peak discharge for 35 different sub-watersheds ...

Ground-penetrating radar methods used in surface-water discharge measurements

USGS Publications Warehouse

Haeni, F.P.; Buursink, Marc L.; Costa, John E.; Melcher, Nick B.; Cheng, Ralph T.; Plant, William J.

2000-01-01

In 1999, an experiment was conducted to see if a combination of complementary radar methods could be used to calculate the discharge of a river without having any of the measuring equipment in the water. The cross-sectional area of the 183-meter wide Skagit River in Washington State was measured using a ground-penetrating radar (GPR) system with a single 100-MHz antenna. A van-mounted, side-looking pulsed-Doppler radar system was used to collect water-surface velocity data across the same section of the river. The combined radar data sets were used to calculate the river discharge and the results compared closely to the discharge measurement made by using the standard in-water measurement techniques.

Initial operation of the NSTX-Upgrade real-time velocity diagnostic

DOE PAGES

Podestà, M.; Bell, R. E.

2016-11-03

A real-time velocity (RTV) diagnostic based on active charge-exchange recombination spectroscopy is now operational on the National Spherical Torus Experiment-Upgrade (NSTX-U) spherical torus (Menard et al 2012 Nucl. Fusion 52 083015). We designed the system in order to supply plasma velocity data in real time to the NSTX-U plasma control system, as required for the implementation of toroidal rotation control. Our measurements are available from four radii at a maximum sampling frequency of 5 kHz. Post-discharge analysis of RTV data provides additional information on ion temperature, toroidal velocity and density of carbon impurities. Furthermore, examples of physics studies enabled bymore » RTV measurements from initial operations of NSTX-U are discussed.« less

Shock-induced vaporization of anhydrite and global cooling from the K/T impact

NASA Astrophysics Data System (ADS)

Gupta, Satish C.; Ahrens, Thomas J.; Yang, Wenbo

2001-06-01

Discovery of abundant anhydrite (CaSO 4) and gypsum (CaSO 4·2H 2O) in the otherwise carbonate sediment comprising the upper 3 km thick layer of the target rock at the K/T impact site has prompted research on these minerals. Evaluation of the severity of the proposed extinction mechanism involving injection of impact-generated SO 2 and SO 3 into the stratosphere entails determination of criteria for shock-induced vaporization of these minerals. In the present work we present new data on the vaporization criteria of anhydrite. These are based on the reanalysis of the shock wave experiments of Yang and Ahrens [Earth Planet. Sci. Lett. 156 (1998) 125-140], conducted on material with 30% porosity, in which the shock- (fully or partially) vaporized sample interacts with an overlying LiF window. The velocity histories, monitored using a velocity interferometer, are compared with numerical simulations employing an improved equation of state for porous anhydrite and its vaporization products. We also employ the 'entropy criterion' for vaporization of material under shock compression. The values of the entropies of incipient and complete vaporization for anhydrite are determined to be 1.65±0.12 and 3.17±0.12 kJ (kg K) -1, respectively, and the corresponding pressures for incipient and the complete vaporization along the Hugoniot for the solid material are 32.5±2.5 and 122±13 GPa, respectively as compared with 81±7 and 155±13 GPa previously reported by Yang and Ahrens. Along with these criteria, the use of the recent estimate of diameter (100 km) for the Chicxulub transient crater [O'Keefe and Ahrens, J. Geophys. Res. 104 (E11) (1999) 27091-27104; Morgan et al., Nature 390 (1997) 472-476] that is smaller than previously assumed, along with Ivanov et al.'s [Geol. Soc. Am. Spec. Pap. 307 (1996) 125-142] 2-D hydrodynamic simulation to determine the shock attenuation and Pope et al.'s [J. Geophys. Res., 102 (E9) (1997) 21645-21664] radiative transfer model, yields the

Using second-sound shock waves to probe the intrinsic critical velocity of liquid helium II

NASA Technical Reports Server (NTRS)

Turner, T. N.

1983-01-01

A critical velocity truly intrinsic to liquid helium II is experimentally sought in the bulk fluid far from the apparatus walls. Termed the 'fundamental critical velocity,' it necessarily is caused by mutual interactions which operate between the two fluid components and which are activated at large relative velocities. It is argued that flow induced by second-sound shock waves provides the ideal means by which to activate and isolate the fundamental critical velocity from other extraneous fluid-wall interactions. Experimentally it is found that large-amplitude second-sound shock waves initiate a breakdown in the superfluidity of helium II, which is dramatically manifested as a limit to the maximum attainable shock strength. This breakdown is shown to be caused by a fundamental critical velocity. Secondary effects include boiling for ambient pressures near the saturated vapor pressure or the formation of helium I boundary layers at higher ambient pressures. When compared to the intrinsic critical velocity discovered in highly restricted geometries, the shock-induced critical velocity displays a similar temperature dependence and is the same order of magnitude.

Vapor phase pyrolysis

NASA Technical Reports Server (NTRS)

Steurer, Wolfgang

1992-01-01

The vapor phase pyrolysis process is designed exclusively for the lunar production of oxygen. In this concept, granulated raw material (soil) that consists almost entirely of metal oxides is vaporized and the vapor is raised to a temperature where it dissociates into suboxides and free oxygen. Rapid cooling of the dissociated vapor to a discrete temperature causes condensation of the suboxides, while the oxygen remains essentially intact and can be collected downstream. The gas flow path and flow rate are maintained at an optimum level by control of the pressure differential between the vaporization region and the oxygen collection system with the aid of the environmental vacuum.

Transient-pressure analysis in geothermal steam reservoirs with an immobile vaporizing liquid phase

USGS Publications Warehouse

Moench, A.F.; Atkinson, P.G.

1978-01-01

A finite-difference model for the radial horizontal flow of steam through a porous medium is used to evaluate transient-pressure behavior in the presence of an immobile vaporizing or condensing liquid phase. Graphs of pressure drawdown and buildup in terms of dimensionless pressure and time are obtained for a well discharging steam at a constant mass flow rate for a specified time. The assumptions are made that the steam is in local thermal equilibrium with the reservoir rocks, that temperature changes are due only to phase change, and that effects of vapor-pressure lowering are negligible. Computations show that when a vaporizing liquid phase is present the pressure drawdown exhibits behavior similar to that observed in noncondensable gas reservoirs, but delayed in time. A theoretical analysis allows for the computation of this delay and demonstrates that it is independent of flow geometry. The response that occurs upon pressure buildup is markedly different from that in a noncondensable gas system. This result may provide a diagnostic tool for establishing the existence of phase-change phenomena within a reservoir. ?? 1979.

Streamflow properties from time series of surface velocity and stage

USGS Publications Warehouse

Plant, W.J.; Keller, W.C.; Hayes, K.; Spicer, K.

2005-01-01

Time series of surface velocity and stage have been collected simultaneously. Surface velocity was measured using an array of newly developed continuous-wave microwave sensors. Stage was obtained from the standard U.S. Geological Survey (USGS) measurements. The depth of the river was measured several times during our experiments using sounding weights. The data clearly showed that the point of zero flow was not the bottom at the measurement site, indicating that a downstream control exists. Fathometer measurements confirmed this finding. A model of the surface velocity expected at a site having a downstream control was developed. The model showed that the standard form for the friction velocity does not apply to sites where a downstream control exists. This model fit our measured surface velocity versus stage plots very well with reasonable values of the parameters. Discharges computed using the surface velocities and measured depths matched the USGS rating curve for the site. Values of depth-weighted mean velocities derived from our data did not agree with those expected from Manning's equation due to the downstream control. These results suggest that if real-time surface velocities were available at a gauging station, unstable stream beds could be monitored. Journal of Hydraulic Engineering ?? ASCE.

Effect of flow velocity on the process of air-steam condensation in a vertical tube condenser

NASA Astrophysics Data System (ADS)

Havlík, Jan; Dlouhý, Tomáš

2018-06-01

This article describes the influence of flow velocity on the condensation process in a vertical tube. For the case of condensation in a vertical tube condenser, both the pure steam condensation process and the air-steam mixture condensation process were theoretically and experimentally analyzed. The influence of steam flow velocity on the value of the heat transfer coefficient during the condensation process was evaluated. For the condensation of pure steam, the influence of flow velocity on the value of the heat transfer coefficient begins to be seen at higher speeds, conversely, this effect is negligible at low values of steam velocity. On the other hand, for the air-steam mixture condensation, the influence of flow velocity must always be taken into account. The flow velocity affects the water vapor diffusion process through non-condensing air. The presence of air significantly reduces the value of the heat transfer coefficient. This drop in the heat transfer coefficient is significant at low velocities; on the contrary, the decrease is relatively small at high values of the velocity.

Molecular Dynamic Simulation of Water Vapor and Determination of Diffusion Characteristics in the Pore

NASA Astrophysics Data System (ADS)

Nikonov, Eduard G.; Pavluš, Miron; Popovičová, Mária

2018-02-01

One of the varieties of pores, often found in natural or artificial building materials, are the so-called blind pores of dead-end or saccate type. Three-dimensional model of such kind of pore has been developed in this work. This model has been used for simulation of water vapor interaction with individual pore by molecular dynamics in combination with the diffusion equation method. Special investigations have been done to find dependencies between thermostats implementations and conservation of thermodynamic and statistical values of water vapor - pore system. The two types of evolution of water - pore system have been investigated: drying and wetting of the pore. Full research of diffusion coefficient, diffusion velocity and other diffusion parameters has been made.

The value of pre-discharge Duplex scanning in infrainguinal graft surveillance.

PubMed

Wilson, Y G; Davies, A H; Currie, I C; McGrath, C; Morgan, M; Baird, R N; Lamont, P M

1995-08-01

Protocols and criteria for Duplex-based graft surveillance programmes (GS) vary widely as to the optimum regimens for maximising detection of "at risk" grafts. Few centres recommend starting GS before discharge. The aim of this study was to audit our experience with respect to early scanning. Vascular Studies Unit, Bristol Royal Infirmary. The records of 123 patients entering GS from January 1992 were reviewed. Patients were scanned at 1 week, 6 weeks and 3, 6, 9 and 12 months post-bypass. Haemodynamic criteria used were a peak mean velocity (PMV) less than 45 cm/s and a focal velocity disturbance with a V2/V1 ratio of 1.5 or more. Forty-six abnormalities (37% detection rate) were identified on scans within one week. In all cases, on-table completion studies with either arteriography and/or flow measurements had failed to identify the anomalies subsequently detected by Duplex. At 1 week, six grafts had occluded, 27 had a focal PMV increase (mean V2/V1 ratio: 2.6; range 1.5-4.3), four had low flow velocities, four had arteriovenous fistulae, one contained mobile thrombus, two had retained cusps and two had hamstring entrapment. Of 40 patent, but compromised grafts, 18 warranted immediate investigation. Of the 27 patients with velocity disturbances on Duplex, 25 were simply observed but, eight have since required intervention for definitive stenoses at these sites which, in retrospect, were evident within the first postoperative week. Pre-discharge scanning is a useful modality for detecting technical problems. Intrinsic graft abnormalities, possibly the sites of future definitive stenoses, have been visualised even at 1 week and once identified, can be more closely scrutinised thereafter. Pre-discharge colour Duplex is recommended as standard practice for quality control after infrainguinal bypass.

Quantification of natural vapor fluxes of trichloroethene in the unsaturated zone at Picatinny Arsenal, New Jersey

USGS Publications Warehouse

Smith, James A.; Tisdale, Amy K.; Cho, H. Jean

1996-01-01

The upward flux of trichloroethene (TCE) vapor through the unsaturated zone above a contaminated, water-table aquifer at Picatinny Arsenal, New Jersey, has been studied under natural conditions over a 12-month period. Vertical gas-phase diffusion fluxes were estimated indirectly by measuring the TCE vapor concentration gradient in the unsaturated zone and using Fick's law to calculate the flux. The total gas-phase flux (e.g., the sum of diffusion and advection fluxes) was measured directly with a vertical flux chamber (VFC). In many cases, the upward TCE vapor flux was several orders of magnitude greater than the upward TCE diffusion flux, suggesting that mechanisms other than steady-state vapor diffusion are contributing to the vertical transport of TCE vapors through the unsaturated zone. The measured total flux of TCE vapor from the subsurface to the atmosphere is approximately 50 kg/yr and is comparable in magnitude to the removal rate of TCE from the aquifer by an existing pump-and-treat system and by discharge into a nearby stream. The net upward flux of TCE is reduced significantly during a storm event, presumably due to the mass transfer of TCE from the soil gas to the infiltrating rainwater and its subsequent downward advection. Several potential problems associated with the measurement of total gas-phase fluxes are discussed.

Electrospun carbon nanofibers surface-grafted with vapor-grown carbon nanotubes as hierarchical electrodes for supercapacitors

NASA Astrophysics Data System (ADS)

Zhou, Zhengping; Wu, Xiang-Fa; Fong, Hao

2012-01-01

This letter reports the fabrication and electrochemical properties of electrospun carbon nanofibers surface-grafted with vapor-grown carbon nanotubes (CNTs) as hierarchical electrodes for supercapacitors. The specific capacitance of the fabricated electrodes was measured up to 185 F/g at the low discharge current density of 625 mA/g; a decrease of 38% was detected at the high discharge current density of 2.5 A/g. The morphology and microstructure of the electrodes were examined by electron microscopy, and the unique connectivity of the hybrid nanomaterials was responsible for the high specific capacitance and low intrinsic contact electric resistance of the hierarchical electrodes.

Vapor Bubbles

NASA Astrophysics Data System (ADS)

Prosperetti, Andrea

2017-01-01

This article reviews the fundamental physics of vapor bubbles in liquids. Work on bubble growth and condensation for stationary and translating bubbles is summarized and the differences with bubbles containing a permanent gas stressed. In particular, it is shown that the natural frequency of a vapor bubble is proportional not to the inverse radius, as for a gas bubble, but to the inverse radius raised to the power 2/3. Permanent gas dissolved in the liquid diffuses into the bubble with strong effects on its dynamics. The effects of the diffusion of heat and mass on the propagation of pressure waves in a vaporous bubbly liquid are discussed. Other topics briefly touched on include thermocapillary flow, plasmonic nanobubbles, and vapor bubbles in an immiscible liquid.

Impact of groundwater levels on evaporation and water-vapor fluxes in highly saline soils

NASA Astrophysics Data System (ADS)

Munoz, J. F.; Hernández, M. F.; Braud, I.; Gironas, J. A.; Suarez, F. I.

2012-12-01

In aquifers of arid and hyper-arid zones, such as those occurring in the Chilean Andes high plateau, it is important to determine both the quantity and location of water discharges at the temporal scales of interest to close the basin's water budget and thus, to manage the water resource properly. In zones where shallow aquifers are the main source of water, overexploitation of the water resource changes the dynamics of water, heat and solute transport in the vadose zone. As aquifers are exploited, fluctuations in depth to groundwater are exacerbated. These fluctuations modify both soil structure and evaporation from the ground, which is typically the most important discharge from the water budget and is very difficult to estimate. Therefore, a correct quantification of evaporation from these soils is essential to improve the accuracy of the water balance estimation. The objective of this study was to investigate the evaporation processes and water-vapor fluxes in a soil column filled with a saline soil from the Salar del Huasco basin, Chile. Water content, electrical conductivity and temperature at different depths in the soil profile were monitored to determine the liquid and vapor fluxes within the soil column. The results showed that evaporation is negligible when the groundwater table is deeper than 1 m. For shallower groundwater levels, evaporation increases in an exponential fashion reaching a value of 3 mm/day when the groundwater table is near the surface of the ground. These evaporation rates are on the same order of magnitude than the field measurements, but slightly lower due to the controlled conditions maintained in the laboratory. Isothermal fluid fluxes were predominant over the non-isothermal fluid and water vapor fluxes. The net flux for all the phreatic levels tested in the laboratory showed different behaviors, with ascending or descending flows as a consequence of changes in water content and temperature distribution within the soil. It was

Physicochemical properties of the AC-excited helium discharges using a water electrode

NASA Astrophysics Data System (ADS)

Hafiz, Imran Ahmad QAZI; Yiying, XIN; Muhammad Ajmal, KHAN; Heping, LI; Lu, ZHOU; Chengyu, BAO

2018-07-01

In this paper, the AC-excited helium discharges generated between the powered needle electrode enclosed in a conical quartz tube and the grounded de-ionized water electrode are investigated. The current and voltage waveforms exhibit a transition from the glow-like to streamer-like mode discharges, which forms a stable cone-shaped structure at the gas–liquid interface. In this region, the air and water vapor diffusion initiate various physical–chemical processes leading to substantial changes of the primary species emission intensities (e.g., OH, N2, NO, and O) and the rotational temperatures. The experimentally measured rotational temperature at the gas–liquid interface is 870 K from the N2(C–B) band with a power input of 26 W. With the prolongation of the discharge time, significant changes in the discharge voltage and current, discharge emission patterns, instantaneous concentrations of the secondary species (e.g., H2O2, {{{NO}}}2-, and {{{NO}}}3-) in the liquid phase, pH values and electrical conductivities of the liquids are observed experimentally. The present study is helpful for deepening the understandings to the basic physical–chemical processes in the discharges in contact with liquids, especially to those occurring in the vicinity of the gas–liquid interface, and also for promoting existing and potential applications of such type of discharges in the fields of environmental protection, biomedicine, agriculture, and so on.

Electrically driven rapidly vaporizing foils, wires and strips used for collision welding and sheet metal forming

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

Vivek, Anupam; Daehn, Glenn S; Taber, Geoffrey A

2015-05-05

A method for forming a piece of a sheet metal is performed by positioning a consumable body, made of metal, proximate to the piece of the sheet metal. The consumable body is rapidly vaporized, and the gas pressure generated thereby is directed into the piece of the sheet metal. This results in acceleration of the piece of sheet metal, and it is collided into a stationary body at a velocity, generally in excess of 200 m/s. Depending upon the type of stationary body, the piece of sheet metal is deformed into a predetermined shape or is welded onto the stationarymore » body. The vaporization is accomplished by passing a high current of electricity into the consumable body. The effect of the vaporized metal may be augmented by additional components in the consumable body.« less

Vacuum vapor deposition

NASA Technical Reports Server (NTRS)

Poorman, Richard M. (Inventor); Weeks, Jack L. (Inventor)

1995-01-01

A method and apparatus is described for vapor deposition of a thin metallic film utilizing an ionized gas arc directed onto a source material spaced from a substrate to be coated in a substantial vacuum while providing a pressure differential between the source and the substrate so that, as a portion of the source is vaporized, the vapors are carried to the substrate. The apparatus includes a modified tungsten arc welding torch having a hollow electrode through which a gas, preferably inert, flows and an arc is struck between the electrode and the source. The torch, source, and substrate are confined within a chamber within which a vacuum is drawn. When the arc is struck, a portion of the source is vaporized and the vapors flow rapidly toward the substrate. A reflecting shield is positioned about the torch above the electrode and the source to ensure that the arc is struck between the electrode and the source at startup. The electrode and the source may be confined within a vapor guide housing having a duct opening toward the substrate for directing the vapors onto the substrate.

Time evolution of nanosecond runaway discharges in air and helium at atmospheric pressure

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

Yatom, S.; Vekselman, V.; Krasik, Ya. E.

2012-12-15

Time- and space-resolved fast framing photography was employed to study the discharge initiated by runaway electrons in air and He gas at atmospheric pressure. Whereas in the both cases, the discharge occurs in a nanosecond time scale and its front propagates with a similar velocity along the cathode-anode gap, the later stages of the discharge differ significantly. In air, the main discharge channels develop and remain in the locations with the strongest field enhancement. In He gas, the first, diode 'gap bridging' stage, is similar to that obtained in air; however, the development of the discharge that follows is dictatedmore » by an explosive electron emission from micro-protrusions on the edge of the cathode. These results allow us to draw conclusions regarding the different conductivity of the plasma produced in He and air discharges.« less

Evaluation of tunable diode laser absorption spectroscopy for in-process water vapor mass flux measurements during freeze drying.

PubMed

Gieseler, Henning; Kessler, William J; Finson, Michael; Davis, Steven J; Mulhall, Phillip A; Bons, Vincent; Debo, David J; Pikal, Michael J

2007-07-01

The goal of this work was to demonstrate the use of Tunable Diode Laser Absorption Spectroscopy (TDLAS) as a noninvasive method to continuously measure the water vapor concentration and the vapor flow velocity in the spool connecting a freeze-dryer chamber and condenser. The instantaneous measurements were used to determine the water vapor mass flow rate (g/s). The mass flow determinations provided a continuous measurement of the total amount of water removed. Full load runs of pure water at different pressure and shelf temperature settings and a 5% (w/w) mannitol product run were performed in both laboratory and pilot scale freeze dryers. The ratio of "gravimetric/TDLAS" measurements of water removed was 1.02 +/- 0.06. A theoretical heat transfer model was used to predict the mass flow rate and the model results were compared to both the gravimetric and TDLAS data. Good agreement was also observed in the "gravimetric/TDLAS" ratio for the 5% mannitol runs dried in both freeze dryers. The endpoints of primary and secondary drying for the product runs were clearly identified. Comparison of the velocity and mass flux profiles between the laboratory and pilot dryers indicated a higher restriction to mass flow for the lab scale freeze dryer. Copyright 2007 Wiley-Liss, Inc.

Field Assessment of Acoustic-Doppler Based Discharge Measurements

USGS Publications Warehouse

Mueller, D.S.; ,

2002-01-01

The use of equipment based on the Doppler principle for measuring water velocity and computing discharge is common within the U.S. Geological Survey (USGS). The instruments and software have changed appreciably during the last 5 years; therefore, the USGS has begun a field validation of the instruments currently (2002) available for making discharge measurements from a moving boat in streams of various sizes. Instruments manufactured by SonTek/YSI2 and RD Instruments, Inc. were used to collect discharge data at five different sites. One or more traditional discharge measurements were made by the use of a Price AA current meter and standard USGS procedures with the acoustic instruments at each site during data collection. The discharges measured with the acoustic instruments were compared with the discharges measured with Price AA meters and the current USGS stage-discharge rating for each site. The mean discharges measured by each acoustic instrument were within 5 percent of the Price AA-based measurement and (or) discharge from the stage-discharge rating. Additional analysis of the data collected indicates that the coefficient of variation of the discharge measurements consistently was less for the RD Instruments, Inc. Rio Grandes than it was for the SonTek/YSI RiverSurveyors. The bottom-tracking referenced measurement had a lower coefficient of variation than the differentially corrected global positioning system referenced measurements. It was observed that the higher frequency RiverSurveyors measured a moving bed more often than the lower frequency Rio Grandes. The detection of a moving bed caused RiverSurveyors to be consistently biased low when referenced to bottom tracking. Differentially corrected global positioning system data may be used to remove the bias observed in the bottom-tracking referenced measurements.

Vapor Intrusion

EPA Pesticide Factsheets

Vapor intrusion occurs when there is a migration of volatile chemicals from contaminated groundwater or soil into an overlying building. Volatile chemicals can emit vapors that may migrate through subsurface soils and into indoor air spaces.

Comparison of electrical and optical characteristics in gas-phase and gas-liquid phase discharges

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

Qazi, H. I. A.; Li, He-Ping, E-mail: liheping@tsinghua.edu.cn; Zhang, Xiao-Fei

This paper presents an AC-excited argon discharge generated using a gas-liquid (two-phase) hybrid plasma reactor, which mainly consists of a powered needle electrode enclosed in a conical quartz tube and grounded deionized water electrode. The discharges in the gas-phase, as well as in the two-phase, exhibit two discharge modes, i.e., the low current glow-like diffuse mode and the high current streamer-like constrict mode, with a mode transition, which exhibits a negative resistance of the discharges. The optical emission spectral analysis shows that the stronger diffusion of the water vapor into the discharge region in the two-phase discharges boosts up themore » generation of OH (A–X) radicals, and consequently, leads to a higher rotational temperature in the water-phase plasma plume than that of the gas-phase discharges. Both the increase of the power input and the decrease of the argon flow rate result in the increase of the rotational temperature in the plasma plume of the water-phase discharge. The stable two-phase discharges with a long plasma plume in the water-phase under a low power input and gas flow rate may show a promising prospect for the degradation of organic pollutants, e.g., printing and dyeing wastewater, in the field of environmental protection.« less

Development of Hydroxyl Tagging Velocimetry for Low Velocity Flows

NASA Technical Reports Server (NTRS)

Andre, Matthieu A.; Bardet, Philippe M.; Burns, Ross A.; Danehy, Paul M.

2016-01-01

Hydroxyl tagging velocimetry (HTV) is a molecular tagging technique that relies on the photo-dissociation of water vapor into OH radicals and their subsequent tracking using laser induced fluorescence. Velocities are then obtained from time-of-flight calculations. At ambient temperature in air, the OH species lifetime is relatively short (<50 µs), making it suited for high speed flows. Lifetime and radicals formation increases with temperature, which allows HTV to also probe low-velocity, high-temperature flows or reacting flows such as flames. The present work aims at extending the domain of applicability of HTV, particularly towards low-speed (<10 m/s) and moderate (<500 K) temperature flows. Results are compared to particle image velocimetry (PIV) measurements recorded in identical conditions. Single shot and averaged velocity profiles are obtained in an air jet at room temperature. By modestly raising the temperature (100-200 degC) the OH production increases, resulting in an improvement of the signal-to-noise ratio (SNR). Use of nitrogen - a non-reactive gas with minimal collisional quenching - extends the OH species lifetime (to over 500 µs), which allows probing of slower flows or, alternately, increases the measurement precision at the expense of spatial resolution. Instantaneous velocity profiles are resolved in a 100degC nitrogen jet (maximum jet-center velocity of 6.5 m/s) with an uncertainty down to 0.10 m/s (1.5%) at 68% confidence level. MTV measurements are compared with particle image velocimetry and show agreement within 2%.

Vapor ingestion in a cylindrical tank with a concave elliptical bottom

NASA Technical Reports Server (NTRS)

Klavins, A.

1974-01-01

An approximate analytical technique is presented for estimating the liquid residual in a tank of arbitrary geometry due to vapor ingestion at any drain rate and acceleration level. The bulk liquid depth at incipient pull-through is defined in terms of the Weber and Bond numbers and two functions that describe the fluid velocity field and free surface shape appropriate to the tank geometry. Numerical results are obtained for the Centaur LH2 tank using limiting approximations to these functions.

Space Debris-de-Orbiting by Vaporization Impulse using Short Pulse Laser

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

Early, J; Bibeau, C; Claude, P

Space debris constitutes a significant hazard to low earth orbit satellites and particularly to manned spacecraft. A quite small velocity decrease from vaporization impulses is enough to lower the perigee of the debris sufficiently for atmospheric drag to de-orbit the debris. A short pulse (picosecond) laser version of the Orion concept can accomplish this task in several years of operation. The ''Mercury'' short pulse Yb:S-FAP laser being developed at LLNL for laser fusion is appropriate for this task.

Explosion symmetry improvement of polyimide-coated tungsten wire in vacuum on negative discharge facility

NASA Astrophysics Data System (ADS)

Li, Mo; Wu, Jian; Lu, Yihan; Li, Xingwen; Li, Yang; Qiu, Mengtong

2018-01-01

Tungsten wire explosion is very asymmetric when fast current rate and insulated coatings are both applied on negative discharge facility using a 24-mm-diameter cathode geometry, which is commonly used on mega-ampere facilities. It is inferred, based on an analytical treatment of the guiding center drift and COMSOL simulations, that the large negative radial electric field causes early voltage breakdown and terminates energy deposition into the wire core on the anode side of the wire. After the anode side is short circuited, the radial electric field along the wire surface on the cathode side will change its polarity and thus leading to additional energy deposition into the wire core. This change causes ˜10 times larger energy deposition and ˜14 times faster explosion velocity in the cathode side than the anode side. In order to reduce this asymmetry, a hollow cylindrical cathode geometry was used to reverse the polarity of radial electric field and was optimized to use on multi-MA facilities. In this case, fully vaporized polyimide-coated tungsten wire with great symmetry improvement was achieved with energy deposition of ˜8.8 eV/atom. The atomic and electronic density distributions for the two different load geometries were obtained by the double-wavelength measurement.

Multi-parameter monitoring of a freshwater submarine groundwater discharge in SW Greece

NASA Astrophysics Data System (ADS)

Karageorgis, A. P.; Papathanassiou, E.

2011-12-01

In 2006, we visited for the first time the area of Kalogria-Stoupa in Peloponnissos, SW Greece, and recorded several submarine groundwater discharges (SGDs), one of which was permanent and very active. The main SGD was easily identified as a wide turbulent gyre (diameter 25-60 m) visible at the sea surface from long distance. Preliminary measurements revealed that freshwater was flowing from the spring at 25 m-depth, and plans for monitoring and potential exploitation were scheduled. The SGD was monitored continuously (measurements every 30 min.) from July 2009 to July 2010 for conductivity, temperature, and flow velocity. An autonomous underwater gamma-ray detector (KATERINA) was used to monitor the radioactivity concentration of radon daughters. During summer, the outflowing water was brackish, with low velocities around 0.2 m s-1. After the first intense rainfalls in mid-October 2009, the SGD emanated steadily low salinity waters (<2), whereas flow velocities exceeded 1.2 m s-1. Estimating that the active discharge area was approx. 1 m2, the spring water discharge varied from 750 to 4.500 m3 h-1 over the year. In May 2010, salinity increased abruptly from 4 to 13 within a few hours, accompanied by a slight decrease of flow velocity. We attribute this change to over-pumping of the carstic aquifer for irrigation in the mainland. Until July 2010, salinity increased furthermore (>20), and then decreased gradually to values ~12. Temperature and salinity variability was very high during some periods, probably due to intense turbulence and in-situ mixing of groundwater and ambient seawater. Radon progenies average activities were proportional to the variations of groundwater discharge, whereas potassium exhibited inverse relationship. The instability of salinity, especially during the summer time, where freshwater would be most needed for irrigation, and in ideal conditions for drinking purposes, terminated any exploitation plans. In mid-July 2011, the SGD without any

Evaluation of the approach based on the concept of hyperbolicity breaking for prediction of flooding velocity of both room temperature and cryogenic fluids

NASA Astrophysics Data System (ADS)

Zhou, Rui; Yu, Liu; Xie, Huangjun; Qiu, Limin; Zhi, Xiaoqin; Zhang, Xiaobin

2018-07-01

The theoretical approach for the prediction of flooding velocity based on the concept of hyperbolicity breaking was evaluated in the counter-current two-phase flow. Detailed mathematical derivations of neutral stability condition together with the correlation of the void fraction are presented. The flooding velocity is obtained by assuming that the wavelength at flooding is proportional to the wavelength of the fastest-growing wave at Helmholtz instability. Some available experimental data for different fluid pair flow in inclined tubes is adopted for comparison with the theoretical calculations, which includes the data of water/air, aqueous oleic acid natrium solution/air, Aq. butanol 2%/air and kerosene/air in the published papers, as well as the liquid nitrogen/vapor nitrogen by the present authors. The comparison of flooding velocity proves that the approach can predict the flooding velocity with accepted accuracy for the water/air and liquid nitrogen/vapor nitrogen flow if the tube diameter is greater than 9 mm. While the diameter is smaller than 9 mm, regardless of the inclinations and the fluid pairs, the error becomes larger relative to the cases of diameter larger than 9 mm. The calculations for small diameter cases also fail to predict the critical liquid velocity at which the flooding velocity of gas reaches the maximum value, as revealed by the experiments. The reasons for the increased errors were qualitatively explained.

Determination of Anisotropic Ion Velocity Distribution Function in Intrinsic Gas Plasma. Theory.

NASA Astrophysics Data System (ADS)

Mustafaev, A.; Grabovskiy, A.; Murillo, O.; Soukhomlinov, V.

2018-02-01

The first seven coefficients of the expansion of the energy and angular distribution functions in Legendre polynomials for Hg+ ions in Hg vapor plasma with the parameter E/P ≈ 400 V/(cm Torr) are measured for the first time using a planar one-sided probe. The analytic solution to the Boltzmann kinetic equation for ions in the plasma of their parent gas is obtained in the conditions when the resonant charge exchange is the predominant process, and ions acquire on their mean free path a velocity much higher than the characteristic velocity of thermal motion of atoms. The presence of an ambipolar field of an arbitrary strength is taken into account. It is shown that the ion velocity distribution function is determined by two parameters and differs substantially from the Maxwellian distribution. Comparison of the results of calculation of the drift velocity of He+ ions in He, Ar+ in Ar, and Hg+ in Hg with the available experimental data shows their conformity. The results of the calculation of the ion distribution function correctly describe the experimental data obtained from its measurement. Analysis of the result shows that in spite of the presence of the strong field, the ion velocity distribution functions are isotropic for ion velocities lower than the average thermal velocity of atoms. With increasing ion velocity, the distribution becomes more and more extended in the direction of the electric field.

High-speed microjet generation using laser-induced vapor bubbles

NASA Astrophysics Data System (ADS)

Oudalov, Nikolai; Tagawa, Yoshiyuki; Peters, Ivo; Visser, Claas-Willem; van der Meer, Devaraj; Prosperetti, Andrea; Sun, Chao; Lohse, Detlef

2011-11-01

The generation and evolution of microjets are studied both experimentally and numerically. The jets are generated by focusing a laser pulse into a microscopic capillary tube (~50 μm) filled with water-based red dye. A vapor bubble is created instantly after shooting the laser (<1 μs), sending out a shockwave towards the curved free surface at which the high-speed microjet forms. The process of jet formation is captured using high-speed recordings at 1.0 × 106 fps. The velocity of the microjets can reach speeds of ~850 m/s while maintaining a very sharp geometry. The high-speed recordings enable us to study the effect of several parameters on the jet velocity, e.g. the absorbed energy and the distance between the laser spot and the free surface.The results show a clear dependence on these variables, even for supersonic speeds. Comparisons with numerical simulations confirm the nature of these dependencies.

Dynamic equilibrium under vibrations of H2 liquid-vapor interface at various gravity levels

NASA Astrophysics Data System (ADS)

Gandikota, G.; Chatain, D.; Lyubimova, T.; Beysens, D.

2014-06-01

Horizontal vibration applied to the support of a simple pendulum can deviate from the equilibrium position of the pendulum to a nonvertical position. A similar phenomenon is expected when a liquid-vapor interface is subjected to strong horizontal vibration. Beyond a threshold value of vibrational velocity the interface should attain an equilibrium position at an angle to the initial horizontal position. In the present paper experimental investigation of this phenomenon is carried out in a magnetic levitation device to study the effect of the vibration parameters, gravity acceleration, and the liquid-vapor density on the interface position. The results compare well with the theoretical expression derived by Wolf [G. H. Wolf, Z. Phys. B 227, 291 (1969), 10.1007/BF01397662].

Preliminary characterization of an expanding flow of siloxane vapor MDM

NASA Astrophysics Data System (ADS)

Spinelli, A.; Cozzi, F.; Cammi, G.; Zocca, M.; Gaetani, P.; Dossena, V.; Guardone, A.

2017-03-01

The early experimental results on the characterization of expanding flows of siloxane vapor MDM (C8H24O2Si3, octamethyltrisiloxane) are presented. The measurements were performed on the Test Rig for Organic VApors (TROVA) at the CREA Laboratory of Politecnico di Milano. The TROVA test-rig was built in order to investigate the non-ideal compressible-fluid behavior of typical expanding flows occurring within organic Rankine cycles (ORC) turbine passages. The test rig implements a batch Rankine cycle where a planar converging-diverging nozzle replaces the turbine and represents a test section. Investigations related to both fields of non-ideal compressible-fluid dynamics fundamentals and turbomachinery are allowed. The nozzle can be operated with different working fluids and operating conditions aiming at measuring independently the pressure, the temperature and the velocity field and thus providing data to verify the thermo-fluid dynamic models adopted to predict the behavior of these flows. The limiting values of pressure and temperature are 50 bar and 400 °C respectively. The early measurements are performed along the nozzle axis, where an isentropic process is expected to occur. In particular, the results reported here refer to the nozzle operated in adapted conditions using the siloxane vapor MDM as working fluid in thermodynamic regions where mild to medium non-ideal compressible-fluid effects are present. Both total temperature and total pressure of the nozzle are measured upstream of the test section, while static pressure are measured along the nozzle axis. Schlieren visualizations are also carried out in order to complement the pressure measurement with information about the 2D density gradient field. The Laser Doppler Velocimetry technique is planned to be used in the future for velocity measurements. The measured flow field has also been interpreted by resorting to the quasi-one-dimensional theory and two dimensional CFD viscous calculation. In both cases

BTSC VAPOR INSTRUSION PRIMER "VAPOR INTRUSION CONSIDERATION FOR REDEVELOPMENT"

EPA Science Inventory

This primer is designed for brownfields stakeholders concerned about vapor intrusion, including property owners, real estate developers, and contractors performing environmental site investigations. It provides an overview of the vapor intrusion issue and how it can impact the ap...

Silo discharge of binary granular mixtures.

PubMed

Madrid, M; Asencio, K; Maza, D

2017-08-01

We present numerical and experimental results on the mass flow rate during the discharge of three-dimensional silos filled with a bidisperse mixture of grains of different sizes. We analyzed the influence of the ratio between coarse and fine particles on the profile of volume fraction and velocity across the orifice. By using numerical simulations, we have shown that the velocity profile has the same shape as that in the monodisperse case and is insensitive to the composition of the mixture. On the contrary, the volume fraction profile is strongly affected by the composition of the mixture. Assuming that an effective particle size can be introduced to characterize the mixture, we have shown that previous expression for the mass flow rate of monodisperse particles can be used for binary mixtures. A comparison with Beverloo's correlation is also presented.

Decomposition of toluene in a steady-state atmospheric-pressure glow discharge

NASA Astrophysics Data System (ADS)

Trushkin, A. N.; Grushin, M. E.; Kochetov, I. V.; Trushkin, N. I.; Akishev, Yu. S.

2013-02-01

Results are presented from experimental studies of decomposition of toluene (C6H5CH3) in a polluted air flow by means of a steady-state atmospheric pressure glow discharge at different water vapor contents in the working gas. The experimental results on the degree of C6H5CH3 removal are compared with the results of computer simulations conducted in the framework of the developed kinetic model of plasma chemical decomposition of toluene in the N2: O2: H2O gas mixture. A substantial influence of the gas flow humidity on toluene decomposition in the atmospheric pressure glow discharge is demonstrated. The main mechanisms of the influence of humidity on C6H5CH3 decomposition are determined. The existence of two stages in the process of toluene removal, which differ in their duration and the intensity of plasma chemical decomposition of C6H5CH3 is established. Based on the results of computer simulations, the composition of the products of plasma chemical reactions at the output of the reactor is analyzed as a function of the specific energy deposition and gas flow humidity. The existence of a catalytic cycle in which hydroxyl radical OH acts a catalyst and which substantially accelerates the recombination of oxygen atoms and suppression of ozone generation when the plasma-forming gas contains water vapor is established.

Mass balance and sliding velocity of the Puget lobe of the cordilleran ice sheet during the last glaciation

USGS Publications Warehouse

Booth, D.B.

1986-01-01

An estimate of the sliding velocity and basal meltwater discharge of the Puget lobe of the Cordilleran ice sheet can be calculated from its reconstructed extent, altitude, and mass balance. Lobe dimensions and surface altitudes are inferred from ice limits and flow-direction indicators. Net annual mass balance and total ablation are calculated from relations empirically derived from modern maritime glaciers. An equilibrium-line altitude between 1200 and 1250 m is calculated for the maximum glacial advance (ca. 15,000 yr B.P.) during the Vashon Stade of the Fraser Glaciation. This estimate is in accord with geologic data and is insensitive to plausible variability in the parameters used in the reconstruction. Resultant sliding velocities are as much as 650 m/a at the equilibrium line, decreasing both up- and downglacier. Such velocities for an ice sheet of this size are consistent with nonsurging behavior. Average meltwater discharge increases monotonically downglacier to 3000 m3/sec at the terminus and is of a comparable magnitude to ice discharge over much of the glacier's ablation area. Palcoclimatic inferences derived from this reconstruction are consistent with previous, independently derived studies of late Pleistocene temperature and precipitation in the Pacific Northwest. ?? 1986.

Modeling fission product vapor transport in the Falcon facility

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

Shepherd, I.M.; Drossinos, Y.; Benson, C.G.

1995-05-01

An extensive database of aerosol Experiments exists and has been used for checking aerosol transport codes. Data for fission product vapor transport are harder to find. Some qualitative data are available, but the Falcon thermal gradient tube tests carried out at AEA Technology`s laboratories in Winfrith, England, mark the first serious attempt to provide a set of experiments suitable for the validation of codes that predict the transport and condensation of realistic mixtures of fission product vapors. Four of these have been analyzed to check how well the computer code VICTORIA can predict the most important phenomena. Of the fourmore » experiments studied, two are reference cases (FAL-17 and FAL-19), one is a case without boric acid (FAL-18), and the other is run in a reducing atmosphere (FAL-20). The results show that once the vapors condense onto aerosols, VICTORIA can predict their deposition rather well. The dominant mechanism is thermophoresis, and each element deposits with more or less the same deposition velocity. The behavior of the vapors is harder to interpret. Essentially, it is important to know the temperature at which each element condenses. It is clear from the measurements that this temperature changed from test to test-caused mostly by the different speciation as the composition of the carrier gas and the relative concentration of other fission products changed. Only in the test with a steam atmosphere and without boric acid was the assumption valid that most of the iodine is cesium iodide and most of the cesium is cesium hydroxide. In general, VICTORIA predicts that, with the exception of cesium, there will be less variation in the speciation-and, hence, variation in the deposition-between tests than is in fact observed. VICTORIA underpredicts the volatility of most elements, and this is partly a consequence of the ideal solution assumption and partly an overestimation of vapor/aerosol interactions.« less

Boundary-value problem for a counterrotating electrical discharge in an axial magnetic field. [plasma centrifuge for isotope separation

NASA Technical Reports Server (NTRS)

Hong, S. H.; Wilhelm, H. E.

1978-01-01

An electrical discharge between two ring electrodes embedded in the mantle of a cylindrical chamber is considered, in which the plasma in the anode and cathode regions rotates in opposite directions under the influence of an external axial magnetic field. The associated boundary-value problem for the coupled partial differential equations describing the azimuthal velocity and radial current-density fields is solved in closed form. The velocity, current density, induced magnetic induction, and electric fields are presented for typical Hartmann numbers, magnetic Reynolds numbers, and geometry parameters. The discharge is shown to produce anodic and cathodic plasma sections rotating at speeds of the order 1,000,000 cm/sec for conventional magnetic field intensities. Possible application of the magnetoactive discharge as a plasma centrifuge for isotope separation is discussed.

Generalized Bohm’s criterion and negative anode voltage fall in electric discharges

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

Londer, Ya. I.; Ul’yanov, K. N., E-mail: kulyanov@vei.ru

2013-10-15

The value of the voltage fall across the anode sheath is found as a function of the current density. Analytic solutions are obtained in a wide range of the ratio of the directed velocity of plasma electrons v{sub 0} to their thermal velocity v{sub T}. It is shown that the voltage fall in a one-dimensional collisionless anode sheath is always negative. At the small values of v{sub 0}/v{sub T}, the obtained expression asymptotically transforms into the Langmuir formula. Generalized Bohm’s criterion for an electric discharge with allowance for the space charge density ρ(0), electric field E(0), ion velocity v{sub i}(0),more » and ratio v{sub 0}/v{sub T} at the plasma-sheath interface is formulated. It is shown that the minimum value of the ion velocity v{sub i}{sup *}(0) corresponds to the vanishing of the electric field at one point inside the sheath. The dependence of v{sub i}{sup *} (0) on ρ(0), E(0), and v{sub 0}/v{sub T} determines the boundary of the existence domain of stationary solutions in the sheath. Using this criterion, the maximum possible degree of contraction of the electron current at the anode is determined for a short high-current vacuum arc discharge.« less

Flow measurements in sewers based on image analysis: automatic flow velocity algorithm.

PubMed

Jeanbourquin, D; Sage, D; Nguyen, L; Schaeli, B; Kayal, S; Barry, D A; Rossi, L

2011-01-01

Discharges of combined sewer overflows (CSOs) and stormwater are recognized as an important source of environmental contamination. However, the harsh sewer environment and particular hydraulic conditions during rain events reduce the reliability of traditional flow measurement probes. An in situ system for sewer water flow monitoring based on video images was evaluated. Algorithms to determine water velocities were developed based on image-processing techniques. The image-based water velocity algorithm identifies surface features and measures their positions with respect to real world coordinates. A web-based user interface and a three-tier system architecture enable remote configuration of the cameras and the image-processing algorithms in order to calculate automatically flow velocity on-line. Results of investigations conducted in a CSO are presented. The system was found to measure reliably water velocities, thereby providing the means to understand particular hydraulic behaviors.

Variation of froude number with discharge for large-gradient steams

USGS Publications Warehouse

Wahl, Kenneth L.; ,

1993-01-01

Under chemical-control conditions, the Froude number (f) for a cross-section can be approximated as a function of the ratio R2/ 3/d 1/2 , where R is the hydraulic radius and d is the average depth. For cross sections where the ratio increases with increasing depth, F can also increase with depth Current-meter measurement data for 433 streamflow gaging stations in Colorado were reviewed, and 62 stations were identified at which F increases with depth of flow. Data for four streamflow gaging stations are presented. In some cases, F approaches 1 as the discharge approaches the magnitude of the median annual peak discharge. The data also indicate that few actual current meter measurement have been made at the large discharges where velocities can be supercritical.

Probe measurements of the electron velocity distribution function in beams: Low-voltage beam discharge in helium

NASA Astrophysics Data System (ADS)

Sukhomlinov, V.; Mustafaev, A.; Timofeev, N.

2018-04-01

Previously developed methods based on the single-sided probe technique are altered and applied to measure the anisotropic angular spread and narrow energy distribution functions of charged particle (electron and ion) beams. The conventional method is not suitable for some configurations, such as low-voltage beam discharges, electron beams accelerated in near-wall and near-electrode layers, and vacuum electron beam sources. To determine the range of applicability of the proposed method, simple algebraic relationships between the charged particle energies and their angular distribution are obtained. The method is verified for the case of the collisionless mode of a low-voltage He beam discharge, where the traditional method for finding the electron distribution function with the help of a Legendre polynomial expansion is not applicable. This leads to the development of a physical model of the formation of the electron distribution function in a collisionless low-voltage He beam discharge. The results of a numerical calculation based on Monte Carlo simulations are in good agreement with the experimental data obtained using the new method.

Highly vibrationally excited CO generated in a low-temperature chemical reaction between carbon vapor and molecular oxygen

NASA Astrophysics Data System (ADS)

Jans, E.; Frederickson, K.; Yurkovich, M.; Musci, B.; Rich, J. W.; Adamovich, I. V.

2016-08-01

A chemical flow reactor is used to study the vibrational population distribution of CO produced by a reaction between carbon vapor generated in an arc discharge and molecular oxygen. The results demonstrate formation of highly vibrationally excited CO, up to vibrational level v = 14, at low temperatures, T = 400-450 K, with population inversion at v = 4-7, in a collision-dominated environment, 15-20 Torr. The average vibrational energy per CO molecule formed by the reaction is 0.6-1.2 eV/molecule, which corresponds to 10-20% of reaction enthalpy. The results show feasibility of development of a new CO chemical laser using carbon vapor and oxygen as reactants.

Double-modulation spectroscopy of molecular ions - Eliminating the background in velocity-modulation spectroscopy

NASA Technical Reports Server (NTRS)

Lan, Guang; Tholl, Hans Dieter; Farley, John W.

1991-01-01

Velocity-modulation spectroscopy is an established technique for performing laser absorption spectroscopy of molecular ions in a discharge. However, such experiments are often plagued by a coherent background signal arising from emission from the discharge or from electronic pickup. Fluctuations in the background can obscure the desired signal. A simple technique using amplitude modulation of the laser and two lock-in amplifiers in series to detect the signal is demonstrated. The background and background fluctuations are thereby eliminated, facilitating the detection of molecular ions.

Effects of Weather Variables on Ascospore Discharge from Fusarium graminearum Perithecia

PubMed Central

Manstretta, Valentina; Rossi, Vittorio

2015-01-01

Fusarium graminearum is a predominant component of the Fusarium head blight (FHB) complex of small grain cereals. Ascosporic infection plays a relevant role in the spread of the disease. A 3-year study was conducted on ascospore discharge. To separate the effect of weather on discharge from the effect of weather on the production and maturation of ascospores in perithecia, discharge was quantified with a volumetric spore sampler placed near maize stalk residues bearing perithecia with mature ascospores; the residues therefore served as a continuous source of ascospores. Ascospores were discharged from perithecia on 70% of 154 days. Rain (R) and vapor pressure deficit (VPD) were the variables that most affected ascospore discharge, with 84% of total discharges occurring on days with R≥0.2 mm or VPD≤11 hPa, and with 70% of total ascospore discharge peaks (≥ 30 ascospores/m3 air per day) occurring on days with R≥0.2 mm and VPD≤6.35 hPa. An ROC analysis using these criteria for R and VPD provided True Positive Proportion (TPP) = 0.84 and True Negative Proportion (TNP) = 0.63 for occurrence of ascospore discharge, and TPP = 0.70 and TNP = 0.89 for occurrence of peaks. Globally, 68 ascospores (2.5% of the total ascospores sampled) were trapped on the 17 days when no ascospores were erroneously predicted. When a discharge occurred, the numbers of F. graminearum ascospores sampled were predicted by a multiple regression model with R2 = 0.68. This model, which includes average and maximum temperature and VPD as predicting variables, slightly underestimated the real data and especially ascospore peaks. Numbers of ascospores in peaks were best predicted by wetness duration of the previous day, minimum temperature, and VPD, with R2 = 0.71. These results will help refine the epidemiological models used as decision aids in FHB management programs. PMID:26402063

Experimental study of flash boiling spray vaporization through quantitative vapor concentration and liquid temperature measurements

NASA Astrophysics Data System (ADS)

Zhang, Gaoming; Hung, David L. S.; Xu, Min

2014-08-01

Flash boiling sprays of liquid injection under superheated conditions provide the novel solutions of fast vaporization and better air-fuel mixture formation for internal combustion engines. However, the physical mechanisms of flash boiling spray vaporization are more complicated than the droplet surface vaporization due to the unique bubble generation and boiling process inside a superheated bulk liquid, which are not well understood. In this study, the vaporization of flash boiling sprays was investigated experimentally through the quantitative measurements of vapor concentration and liquid temperature. Specifically, the laser-induced exciplex fluorescence technique was applied to distinguish the liquid and vapor distributions. Quantitative vapor concentration was obtained by correlating the intensity of vapor-phase fluorescence with vapor concentration through systematic corrections and calibrations. The intensities of two wavelengths were captured simultaneously from the liquid-phase fluorescence spectra, and their intensity ratios were correlated with liquid temperature. The results show that both liquid and vapor phase of multi-hole sprays collapse toward the centerline of the spray with different mass distributions under the flash boiling conditions. Large amount of vapor aggregates along the centerline of the spray to form a "gas jet" structure, whereas the liquid distributes more uniformly with large vortexes formed in the vicinity of the spray tip. The vaporization process under the flash boiling condition is greatly enhanced due to the intense bubble generation and burst. The liquid temperature measurements show strong temperature variations inside the flash boiling sprays with hot zones present in the "gas jet" structure and vortex region. In addition, high vapor concentration and closed vortex motion seem to have inhibited the heat and mass transfer in these regions. In summary, the vapor concentration and liquid temperature provide detailed information

Fractal structure of low-temperature plasma of arc discharge as a consequence of the interaction of current sheets

NASA Astrophysics Data System (ADS)

Smolanov, N. A.

2016-01-01

The structure of the particles deposited from the plasma arc discharge were studied. The flow of plasma spreading from the cathode spot to the walls of the vacuum chamber. Electric and magnetic fields to influence the plasma flow. The fractal nature of the particles from the plasma identified by small-angle X-ray scattering. Possible cause of their formation is due to the instability of the growth front and nonequilibrium conditions for their production - a high speed transition of the vapor-liquid-solid or vapor - crystal. The hypothesis of a plasma arc containing dust particles current sheets was proposed.

A 10-cm Discharge-Length He-ZnII White Light Laser

NASA Astrophysics Data System (ADS)

Sasaki, Wakao; Itani, Kimihiko; Ohta, Tatehisa

1989-06-01

We demonstrate a unique, efficient white light laser source realized by the He-Zn mixture with substantially short discharge length of 10 cm. The white laser light can be made up of only two wavelengths at simultaneous oscillation --- 492.4 nm (4f2Fo712_4d2D5/2) and 610.2 nm (5d 2D 512 -5 2p03/2 The ideal white color region for human eyes lies just between these two wavelengths in the chromaticity diagram. Therefore, such a compact white light laser will be useful for some specific purposes such as a white color standard. Moreover, we have analyzed the proper relation between the electron energy and the discharge sustaining voltage which appears as a function of the Zn vapor pressure measured at the terminal of the tube, considering the Druyvesteyn distribution of electron energy. Then we succeeded to operate a He-Zn laser tube in white light with 10-cm discharge length. The derived output beam was estimated to be about 0.5 mW.

Stratospheric water vapor feedback.

PubMed

Dessler, A E; Schoeberl, M R; Wang, T; Davis, S M; Rosenlof, K H

2013-11-05

We show here that stratospheric water vapor variations play an important role in the evolution of our climate. This comes from analysis of observations showing that stratospheric water vapor increases with tropospheric temperature, implying the existence of a stratospheric water vapor feedback. We estimate the strength of this feedback in a chemistry-climate model to be +0.3 W/(m(2)⋅K), which would be a significant contributor to the overall climate sensitivity. One-third of this feedback comes from increases in water vapor entering the stratosphere through the tropical tropopause layer, with the rest coming from increases in water vapor entering through the extratropical tropopause.

Stratospheric water vapor feedback

PubMed Central

Dessler, A. E.; Schoeberl, M. R.; Wang, T.; Davis, S. M.; Rosenlof, K. H.

2013-01-01

We show here that stratospheric water vapor variations play an important role in the evolution of our climate. This comes from analysis of observations showing that stratospheric water vapor increases with tropospheric temperature, implying the existence of a stratospheric water vapor feedback. We estimate the strength of this feedback in a chemistry–climate model to be +0.3 W/(m2⋅K), which would be a significant contributor to the overall climate sensitivity. One-third of this feedback comes from increases in water vapor entering the stratosphere through the tropical tropopause layer, with the rest coming from increases in water vapor entering through the extratropical tropopause. PMID:24082126

Thermodynamic Properties of Nitrogen Including Liquid and Vapor Phases from 63K to 2000K with Pressures to 10,000 Bar

NASA Technical Reports Server (NTRS)

Jacobsen, Richard T.; Stewart, Richard B.

1973-01-01

Tables of thermodynamic properties of nitrogen are presented for the liquid and vapor phases for temperatures from the freezing line to 2000K and pressures to 10,000 bar. The tables include values of density, internal energy, enthalpy, entropy, isochoric heat capacity, isobaric heat capacity velocity of sound, the isotherm derivative, and the isochor derivative. The thermodynamic property tables are based on an equation of state, P=P (p,T), which accurately represents liquid and gaseous nitrogen for the range of pressures and temperatures covered by the tables. Comparisons of property values calculated from the equation of state with measured values for P-p-T, heat capacity, enthalpy, latent heat, and velocity of sound are included to illustrate the agreement between the experimental data and the tables of properties presented here. The coefficients of the equation of state were determined by a weighted least squares fit to selected P-p-T data and, simultaneously, to isochoric heat capacity data determined by corresponding states analysis from oxygen data, and to data which define the phase equilibrium criteria for the saturated liquid and the saturated vapor. The vapor pressure equation, melting curve equation, and an equation to represent the ideal gas heat capacity are also presented. Estimates of the accuracy of the equation of state, the vapor pressure equation, and the ideal gas heat capacity equation are given. The equation of state, derivatives of the equation, and the integral functions for calculating derived thermodynamic properties are included.

Method and apparatus for vapor detection

NASA Technical Reports Server (NTRS)

Lerner, Melvin (Inventor); Hood, Lyal V. (Inventor); Rommel, Marjorie A. (Inventor); Pettitt, Bruce C. (Inventor); Erikson, Charles M. (Inventor)

1980-01-01

The method disclosed herein may be practiced by passing the vapors to be sampled along a path with halogen vapor, preferably chlorine vapor, heating the mixed vapors to halogenate those of the sampled vapors subject to halogenation, removing unreacted halogen vapor, and then sensing the vapors for organic halogenated compounds. The apparatus disclosed herein comprises means for flowing the vapors, both sample and halogen vapors, into a common path, means for heating the mixed vapors to effect the halogenation reaction, means for removing unreacted halogen vapor, and a sensing device for sensing halogenated compounds. By such a method and means, the vapors of low molecular weight hydrocarbons, ketones and alcohols, when present, such as methane, ethane, acetone, ethanol, and the like are converted, at least in part, to halogenated compounds, then the excess halogen removed or trapped, and the resultant vapors of the halogenated compounds sensed or detected. The system is highly sensitive. For example, acetone in a concentration of 30 parts per billion (volume) is readily detected.

Experiences of marijuana-vaporizer users.

PubMed

Malouff, John M; Rooke, Sally E; Copeland, Jan

2014-01-01

Using a marijuana vaporizer may have potential harm-reduction advantages on smoking marijuana, in that the user does not inhale smoke. Little research has been published on use of vaporizers. In the first study of individuals using a vaporizer on their own initiative, 96 adults anonymously answered questions about their experiences with a vaporizer and their use of marijuana with tobacco. Users identified 4 advantages to using a vaporizer over smoking marijuana: perceived health benefits, better taste, no smoke smell, and more effect from the same amount of marijuana. Users identified 2 disadvantages: inconvenience of setup and cleaning and the time it takes to get the device operating for each use. Only 2 individuals combined tobacco in the vaporizer mix, whereas 15 combined tobacco with marijuana when they smoked marijuana. Almost all participants intended to continue using a vaporizer. Vaporizers seem to have appeal to marijuana users, who perceive them as having harm-reduction and other benefits. Vaporizers are worthy of experimental research evaluating health-related effects of using them.

Dielectric barrier discharge atmospheric cold plasma inhibits Escherichia coli 0157:H7, Salmonella, Listeria monocytogenes, and Tulane virus in Romaine lettuce

USDA-ARS?s Scientific Manuscript database

The present study investigated the effects of dielectric barrier discharge atmospheric cold plasma (DACP) treatment on the inactivation of Escherichia coli O157:H7, Salmonella, Listeria monocytogenes, and Tulane virus (TV) on Romaine lettuce, assessing the influences of moisture vaporization, modifi...

Lox droplet vaporization in a supercritical forced convective environment

NASA Technical Reports Server (NTRS)

Hsiao, Chia-Chun; Yang, Vigor

1994-01-01

A systematic investigation has been conducted to study the effects of ambient flow conditions (i.e. pressure and velocity) on supercritical droplet gasification in a forced-convective environment. The model is based on the time-dependent conservation equations in axisymmetric coordinates, and accommodates thermodynamic nonidealities and transport anomalies. In addition, an efficient scheme for evaluating thermophysical properties over the entire range of fluid thermodynamic states is established. The analysis allows a thorough examination of droplet behavior during its entire lifetime, including transient gasification, dynamic deformation, and shattering. A parametric study of droplet vaporization rate in terms of ambient pressure and Reynolds number is also conducted.

Gasoline Vapor Recovery

NASA Technical Reports Server (NTRS)

1979-01-01

Gasoline is volatile and some of it evaporates during storage, giving off hydrocarbon vapor. Formerly, the vapor was vented into the atmosphere but anti-pollution regulations have precluded that practice in many localities, so oil companies and storage terminals are installing systems to recover hydrocarbon vapor. Recovery provides an energy conservation bonus in that most of the vapor can be reconverted to gasoline. Two such recovery systems are shown in the accompanying photographs (mid-photo at right and in the foreground below). They are actually two models of the same system, although.configured differently because they are customized to users' needs. They were developed and are being manufactured by Edwards Engineering Corporation, Pompton Plains, New Jersey. NASA technological information proved useful in development of the equipment.

Experimental investigation on the effect of plasma jet in the triggered discharge process of a gas switch

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

Tie, W., E-mail: twh.110.666@163.com, E-mail: 84470220@qq.com; Xi'an Jiaotong University, Xi'an 710049; Liu, S.

The temporal and spatial evolution of a plasma jet generated by a spark discharge was observed. The electron temperature and density were obtained under different time and gas pressures by optical emission spectroscopy. Moreover, the discharge process of the plasma-jet triggered gas switch was recorded and analyzed at the lowest working coefficient. The results showed that the plasma jet moved forward in a bullet mode, and the advancing velocity increased with the decrease of pressure, and decreased with time growing. At initial time, the maximum velocity of a plasma jet could reach 3.68 × 10{sup 6 }cm/s. The electron temperature decreased from 2.0 eVmore » to 1.3 eV, and the electron density increased from 3.1 × 10{sup 15}/cm{sup 3} to 6.3 × 10{sup 15}/cm{sup 3} at the initial moment as the gas pressure increases from 0.1 MPa to 0.32 MPa. For a two-gap gas switch, the discharge performances were more depended on the second discharge spark gap (gap 2). Because plasma jet promoted the discharge in Gap 2, the gas switch operating in mode II had better triggered discharge characteristics. In the discharge process, the plasma-jet triggering had the effect of non-penetrating inducing, which not only provided initial electrons for reducing statistical lag but also enhanced the local electric field. The discharge was initiated and accelerated from electron avalanche to streamer. Therefore, a fast discharge was occurred in the gas switch.« less

Estimating Discharge, Depth and Bottom Friction in Sand Bed Rivers Using Surface Currents and Water Surface Elevation Observations

NASA Astrophysics Data System (ADS)

Simeonov, J.; Czapiga, M. J.; Holland, K. T.

2017-12-01

We developed an inversion model for river bathymetry estimation using measurements of surface currents, water surface elevation slope and shoreline position. The inversion scheme is based on explicit velocity-depth and velocity-slope relationships derived from the along-channel momentum balance and mass conservation. The velocity-depth relationship requires the discharge value to quantitatively relate the depth to the measured velocity field. The ratio of the discharge and the bottom friction enter as a coefficient in the velocity-slope relationship and is determined by minimizing the difference between the predicted and the measured streamwise variation of the total head. Completing the inversion requires an estimate of the bulk friction, which in the case of sand bed rivers is a strong function of the size of dune bedforms. We explored the accuracy of existing and new empirical closures that relate the bulk roughness to parameters such as the median grain size diameter, ratio of shear velocity to sediment fall velocity or the Froude number. For given roughness parameterization, the inversion solution is determined iteratively since the hydraulic roughness depends on the unknown depth. We first test the new hydraulic roughness parameterization using estimates of the Manning roughness in sand bed rivers based on field measurements. The coupled inversion and roughness model is then tested using in situ and remote sensing measurements of the Kootenai River east of Bonners Ferry, ID.

Runaway electron beam control for longitudinally pumped metal vapor lasers

NASA Astrophysics Data System (ADS)

Kolbychev, G. V.; Kolbycheva, P. D.

1995-08-01

Physics and techniques for producing of the pulsed runaway electron beams are considered. The main obstacle for increasing electron energies in the beams is revealed to be a self- breakdown of the e-gun's gas-filled diode. Two methods to suppress the self-breakdown and enhance the volumetric discharge producing the e-beam are offered and examined. Each of them provides 1.5 fold increase of the ceiling potential on the gun. The methods also give the ways to control several guns simultaneously. Resulting in the possibility of realizing the powerful longitudinal pumping of metal-vapor lasers on self-terminated transitions of atoms or ions.

Measurement of OH, O, and NO densities and their correlations with mouse melanoma cell death rate treated by a nanosecond pulsed streamer discharge

NASA Astrophysics Data System (ADS)

Yagi, Ippei; Shirakawa, Yuki; Hirakata, Kenta; Akiyama, Taketoshi; Yonemori, Seiya; Mizuno, Kazue; Ono, Ryo; Oda, Tetsuji

2015-10-01

Mouse melanoma cells in a culture medium are treated using a nanosecond pulsed streamer discharge plasma and the correlations between the rate of cell death and the densities of reactive species (OH, O, and NO) in the plasma are measured. The plasma is irradiated onto the culture medium surface with a vertical gas flow of an O2/N2 mixture from a glass tube at various gas flow rates and O2 concentrations. The densities of the reactive species are measured very close to the culture medium surface, where the reactive species interact with the culture medium, using laser-induced fluorescence. In the case of the N2 discharge (O2 = 0%), an increase in gas flow rate decreases OH density because it lowers the water vapor concentration by diluting the vapor, which is required for OH production. The increase in gas flow rate also leads to a decreased cell death rate. In the case of the O2/N2 discharge, on the other hand, an increase in O2 concentration at a fixed flow rate does not affect the rate of cell death, although it considerably changes the O and NO densities. These findings indicate that some reactive species derived from water vapor such as OH are responsible for the melanoma cell death, whereas those from O2, such as O and NO, are less likely responsible. They also indicate the importance of water evaporation from the culture medium surface in cell treatment.

Model for toroidal velocity in H-mode plasmas in the presence of internal transport barriers

NASA Astrophysics Data System (ADS)

Chatthong, B.; Onjun, T.; Singhsomroje, W.

2010-06-01

A model for predicting toroidal velocity in H-mode plasmas in the presence of internal transport barriers (ITBs) is developed using an empirical approach. In this model, it is assumed that the toroidal velocity is directly proportional to the local ion temperature. This model is implemented in the BALDUR integrated predictive modelling code so that simulations of ITB plasmas can be carried out self-consistently. In these simulations, a combination of a semi-empirical mixed Bohm/gyro-Bohm (mixed B/gB) core transport model that includes ITB effects and NCLASS neoclassical transport is used to compute a core transport. The boundary is taken to be at the top of the pedestal, where the pedestal values are described using a theory-based pedestal model based on a combination of magnetic and flow shear stabilization pedestal width scaling and an infinite-n ballooning pressure gradient model. The combination of the mixed B/gB core transport model with ITB effects, together with the pedestal and the toroidal velocity models, is used to simulate the time evolution of plasma current, temperature and density profiles of 10 JET optimized shear discharges. It is found that the simulations can reproduce an ITB formation in these discharges. Statistical analyses including root mean square error (RMSE) and offset are used to quantify the agreement. It is found that the averaged RMSE and offset among these discharges are about 24.59% and -0.14%, respectively.

Effect of Doppler flow meter position on discharge measurement in surcharged manholes.

PubMed

Yang, Haoming; Zhu, David Z; Liu, Yanchen

2018-02-01

Determining the proper installation location of flow meters is important for accurate measurement of discharge in sewer systems. In this study, flow field and flow regimes in two types of manholes under surcharged flow were investigated using a commercial computational fluid dynamics (CFD) code. The error in measuring the flow discharge using a Doppler flow meter (based on the velocity in a Doppler beam) was then estimated. The values of the corrective coefficient were obtained for the Doppler flow meter at different locations under various conditions. Suggestions for selecting installation positions are provided.

Vapor Discharges On Nevado Del Ruiz During The Recent Activity: Clues On The Composition Of The Deep Hydrothermal System And Its Effects On Thermal Springs

NASA Astrophysics Data System (ADS)

Inguaggiato, S.; Federico, C.; Chacon, Z.; Londono, J. M.; Alzate, D. M.; Gil, E.

2015-12-01

in the magmatic input into the hydrothermal system could modify its degree of vaporization and/or P-T-X conditions, thus inducing corresponding variations in vapour discharges and thermal waters. These findings, paralleled by contemporary measurements of water flow rates, could give significant clues on risk evaluation at NdR.

Greener corona discharge for enhanced wind generation with a simple dip-coated carbon nanotube decoration

NASA Astrophysics Data System (ADS)

Wu, Yishan; Li, Jun; Ye, Jianchun; Chen, Xiaohong; Li, Huili; Huang, Sumei; Zhao, Ran; Ou-Yang, Wei

2017-10-01

Corona discharge-induced wind (CDIW) has been widely utilized in production lines in the food and semiconductor industries and in indoor devices such as electrostatic precipitators. Some ozone is inevitably emitted, posing serious health risks to respiratory system and lung function of a human being. In this work, a greener corona discharge with enhanced wind generation for a needle-to-cylinder discharge structure is demonstrated using a simple dip-coating method to attach carbon nanotubes (CNTs) to the discharge electrode of a stainless steel needle. Compared with a conventional discharge electrode without CNT decoration, the velocity of the CDIW is greatly enhanced, the onset voltage is lowered, the energy conversion efficiency is greatly improved and the concentration of generated ozone is much reduced, making this easy method of CNT decoration a promising candidate for greener corona discharge systems. In addition, several impact factors for improved performance are discussed mathematically and phenomenologically, providing an insight into the corona discharge and wind generation.

Non-closure of the surface energy balance explained by phase difference between vertical velocity and scalars of large atmospheric eddies

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

Gao, Zhongming; Liu, Heping; Katul, Gabriel G.

It is now accepted that large-scale turbulent eddies impact the widely reported non-closure of the surface energy balance when latent and sensible heat fluxes are measured using the eddy covariance method in the atmospheric surface layer (ASL). However, a mechanistic link between large eddies and non-closure of the surface energy balance remains a subject of inquiry. Here, measured 10 Hz time series of vertical velocity, air temperature, and water vapor density collected in the ASL are analyzed for conditions where entrainment and/or horizontal advection separately predominate. The series are decomposed into small- and large- eddies based on a frequency cutoffmore » and their contributions to turbulent fluxes are analyzed. Phase difference between vertical velocity and water vapor density associated with large eddies reduces latent heat fluxes, especially in conditions where advection prevails. Furthermore, enlarged phase difference of large eddies linked to entrainment or advection occurrence leads to increased residuals of the surface energy balance.« less

Non-closure of the surface energy balance explained by phase difference between vertical velocity and scalars of large atmospheric eddies

DOE PAGES

Gao, Zhongming; Liu, Heping; Katul, Gabriel G.; ...

2017-03-16

It is now accepted that large-scale turbulent eddies impact the widely reported non-closure of the surface energy balance when latent and sensible heat fluxes are measured using the eddy covariance method in the atmospheric surface layer (ASL). However, a mechanistic link between large eddies and non-closure of the surface energy balance remains a subject of inquiry. Here, measured 10 Hz time series of vertical velocity, air temperature, and water vapor density collected in the ASL are analyzed for conditions where entrainment and/or horizontal advection separately predominate. The series are decomposed into small- and large- eddies based on a frequency cutoffmore » and their contributions to turbulent fluxes are analyzed. Phase difference between vertical velocity and water vapor density associated with large eddies reduces latent heat fluxes, especially in conditions where advection prevails. Furthermore, enlarged phase difference of large eddies linked to entrainment or advection occurrence leads to increased residuals of the surface energy balance.« less

Means and method for vapor generation

DOEpatents

Carlson, Larry W.

1984-01-01

A liquid, in heat transfer contact with a surface heated to a temperature well above the vaporization temperature of the liquid, will undergo a multiphase (liquid-vapor) transformation from 0% vapor to 100% vapor. During this transition, the temperature driving force or heat flux and the coefficients of heat transfer across the fluid-solid interface, and the vapor percentage influence the type of heating of the fluid--starting as "feedwater" heating where no vapors are present, progressing to "nucleate" heating where vaporization begins and some vapors are present, and concluding with "film" heating where only vapors are present. Unstable heating between nucleate and film heating can occur, accompanied by possibly large and rapid temperature shifts in the structures. This invention provides for injecting into the region of potential unstable heating and proximate the heated surface superheated vapors in sufficient quantities operable to rapidly increase the vapor percentage of the multiphase mixture by perhaps 10-30% and thereby effectively shift the multiphase mixture beyond the unstable heating region and up to the stable film heating region.

Means and method for vapor generation

DOEpatents

Carlson, L.W.

A liquid, in heat transfer contact with a surface heated to a temperature well above the vaporization temperature of the liquid, will undergo a multiphase (liquid-vapor) transformation from 0% vapor to 100% vapor. During this transition, the temperature driving force or heat flux and the coefficients of heat transfer across the fluid-solid interface, and the vapor percentage influence the type of heating of the fluid - starting as feedwater heating where no vapors are present, progressing to nucleate heating where vaporization begins and some vapors are present, and concluding with film heating where only vapors are present. Unstable heating between nucleate and film heating can occur, accompanied by possibly large and rapid temperature shifts in the structures. This invention provides for injecting into the region of potential unstable heating and proximate the heated surface superheated vapors in sufficient quantities operable to rapidly increase the vapor percentage of the multiphase mixture by perhaps 10 to 30% and thereby effectively shift the multiphase mixture beyond the unstable heating region and up to the stable film heating region.

Neurophysiological assessment of auditory, peripheral nerve, somatosensory, and visual system functions after developmental exposure to ethanol vapors.

PubMed

Boyes, William K; Degn, Laura L; Martin, Sheppard A; Lyke, Danielle F; Hamm, Charles W; Herr, David W

2014-01-01

Ethanol-blended gasoline entered the market in response to demand for domestic renewable energy sources, and may result in increased inhalation of ethanol vapors in combination with other volatile gasoline constituents. It is important to understand potential risks of inhalation of ethanol vapors by themselves, and also as a baseline for evaluating the risks of ethanol combined with a complex mixture of hydrocarbon vapors. Because sensory dysfunction has been reported after developmental exposure to ethanol, we evaluated the effects of developmental exposure to ethanol vapors on neurophysiological measures of sensory function as a component of a larger project evaluating developmental ethanol toxicity. Pregnant Long-Evans rats were exposed to target concentrations 0, 5000, 10,000, or 21,000 ppm ethanol vapors for 6.5h/day over GD9-GD20. Sensory evaluations of male offspring began between PND106 and PND128. Peripheral nerve function (compound action potentials, nerve conduction velocity (NCV)), somatosensory (cortical and cerebellar evoked potentials), auditory (brainstem auditory evoked responses), and visual evoked responses were assessed. Visual function assessment included pattern elicited visual evoked potentials (VEPs), VEP contrast sensitivity, and electroretinograms recorded from dark-adapted (scotopic), light-adapted (photopic) flashes, and UV flicker and green flicker. No consistent concentration-related changes were observed for any of the physiological measures. The results show that gestational exposure to ethanol vapor did not result in detectable changes in peripheral nerve, somatosensory, auditory, or visual function when the offspring were assessed as adults. Published by Elsevier Inc.

Graphene by one-step chemical vapor deposition from ferrocene vapors: Properties and electrochemical evaluation

NASA Astrophysics Data System (ADS)

Pilatos, George; Perdikaki, Anna V.; Sapalidis, Andreas; Pappas, George S.; Giannakopoulou, Tatiana; Tsoutsou, Dimitra; Xenogiannopoulou, Evangelia; Boukos, Nikos; Dimoulas, Athanasios; Trapalis, Christos; Kanellopoulos, Nick K.; Karanikolos, Georgios N.

2016-02-01

Growth of few-layer graphene using ferrocene as precursor by chemical vapor deposition is reported. The growth did not involve any additional carbon or catalyst source or external hydrocarbon gases. Parametric investigation was performed using different conditions, namely, varying growth temperature from 600 to1000 °C, and growth duration from 5 min to 3 h, as well as using fast quenching or gradual cooling after the thermal treatment, in order to examine the effect on the quality of the produced graphene. The growth took place on silicon wafers and resulted, under optimal conditions, in formation of graphene with 2-3 layers and high graphitic quality, as evidenced by Raman spectroscopy, with characteristic full width at half maximum of the 2D band of 49.46 cm-1, and I2D/IG and ID/IG intensity ratios of 1.15 and 0.26, respectively. Atomic force microscopy and X-ray photoelectron spectroscopy were employed to further evaluate graphene characteristics and enlighten growth mechanism. Electrochemical evaluation of the developed material was performed using cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge-discharge measurements.

Operation characteristic of a heat pump of mechanical vapor recompression propelled by fans and its performance analysis applied to waste-water treatment

NASA Astrophysics Data System (ADS)

Weike, Pang; Wenju, Lin; Qilin, Pan; Wenye, Lin; Qunte, Dai; Luwei, Yang; Zhentao, Zhang

2014-01-01

In this paper, a set of heat pump (called as Mechanical Vapor Recompression, MVR) propelled by a centrifugal fan is tested and it shows some special characteristic when it works together with a falling film evaporator. Firstly, an analysis of the fan's suction and discharge parameters at stable state, such as its pressure and temperature, indicates that a phenomenon of wet compression is probably to appear during vapor compression. As a result, superheat after saturated vapor is compressed is eliminated, which reduces discharge temperature of the system. It is because drops boil away and absorb the super heat into their latent heat during vapor compression. Meanwhile, drops in the suction vapor add to the compressed vapor, which increase the given heat of the MVR heat pump. Next, assistant electric heat could adjust and keep steady of the operating pressure and temperature of an MVR heat pump. With the evaporation temperature up to be high, heat balance is broken and supplement heat needs to increase. Thirdly, the performance of an MVR heat pump is affect by the balance of falling film and evaporation that has an effect on heat transfer. Then, two parameters standing for the performance are measured as it runs in practical condition. The two important parameters are consumptive electricity power and productive water capacity. According to theoretical work in ideal condition by calculation and fan's input power by measure as running, adiabatic efficiency (ηad) of a centrifugal fan is calculated when it is applied in a heat pump of MVR. Following, based on ηad, practical SMER and COP of an MVR heat pump are discovered to be correlative with it. Finally, in dependence on productive water in theory and in practice, displacement efficiency (ηv) of centrifugal fans is obtained when compressing vapor, and so provide some references of matching a fan for an MVR heat pump. On the other hand, it is helpful to research and develop MVR heat pumps, and also to check

Discharge Measurements in Shallow Urban Streams Using a Hydroacoustic Current Meter

USGS Publications Warehouse

Fisher, G.T.; Morlock, S.E.; ,

2002-01-01

Hydroacoustic current-meter measurements were evaluated in small urban streams under a range of stages, velocities, and channel-bottom materials. Because flow in urban streams is often shallow, conventional mechanical current-meter measurements are difficult or impossible to make. The rotating-cup Price pygmy meter that is widely used by the U.S. Geological Survey and other agencies should not be used in depths below 0.20 ft and velocities less than 0.30 ft/s. The hydroacoustic device provides measurements at depths as shallow as 0.10 ft and velocities as low as 0.10 ft/s or less. Measurements using the hydroacoustic current meter were compared to conventional discharge measurements. Comparisons with Price-meter measurements were favorable within the range of flows for which the meters are rated. Based on laboratory and field tests, velocity measurements with the hydroacoustic cannot be validated below about 0.07 ft/s. However, the hydroacoustic meter provides valuable information on direction and magnitude of flow even at lower velocities, which otherwise could not be measured with conventional measurements.

Air velocity distributions inside tree canopies from a variable-rate air-assisted sprayer

USDA-ARS?s Scientific Manuscript database

A variable-rate, air assisted, five-port sprayer had been in development to achieve variable discharge rates of both liquid and air. To verify the variable air rate capability by changing the fan inlet diameter of the sprayer, air jet velocities impeded by plant canopies were measured at various loc...

Short-range splash discharge of peridioles in Nidularia.

PubMed

Hassett, Maribeth O; Fischer, Mark W F; Money, Nicholas P

2015-06-01

The distinctive shapes of basidiomata in the bird's nest fungi reflect differences in the mechanism of splash discharge. In the present study, peridiole discharge was examined in Nidularia pulvinata using high-speed video. Nidularia pulvinata produces globose basidiomata that split open at maturity to expose 100 or more peridioles within a gelatinous matrix. Each peridiole contains an estimated 7 million spores. The impact of water drops splashed the peridioles horizontally from the fruit body, along with globs of mucilage, at a mean velocity of 1.2 m s(-1). Discharged peridioles travelled for a maximum horizontal distance of 1.5 cm. This launch process contrasts with the faster vertical splashes of peridioles over distances of up to one metre from the flute-shaped fruit bodies of bird's nest fungi in the genera Crucibulum and Cyathus. Peridioles in these genera are equipped with a funicular cord that attaches them to vegetation, placing them in an ideal location for ingestion by browsing herbivores. The absence of cords in N. pulvinata and its use of a sloppy discharge mechanism suggest that it is more likely to be dispersed by animals feeding on the forest floor. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Reconnaissance investigations of the discharge and water quality of the Amazon River

USGS Publications Warehouse

Oltman, Roy Edwin

1968-01-01

effect reaches upstream to Obidos at extremely low flows, the distribution of velocities in stream verticals is affected by large-scale turbulence, the standard procedure of basing mean velocity in vertical on the average of point velocities measured at 20 and 80 percent of the total depth is valid, and there is a low Manning roughness coefficient of 0.019 (English units). Samples of suspended sediment taken with a point sampler at various depths in selected verticals show, for the Obidos site, a variation in concentration from 300 to 340 mg/l (milligram per liter) near the streambed to 50 to 70 mg/l in the upper part of the verticals. Median diameter of bed material at Obidos averaged about 0.20 mm (millimeter) in a range of 0.15 to 0.25 ram. Analyses of water samples collected at Obidos in July and November 1963 and August 1964 are presented. The reconnaissance measurements of 1963-64 provide a well-supported value of mean annual water discharge of Amazon River at Obidos and the mouth. Many more measurements of flow and water-quality characteristics are needed to obtain more exact values of discharge, suspended sediment, and salt load.

Plasma-Powder Feedstock Interaction During Plasma Spray-Physical Vapor Deposition

NASA Astrophysics Data System (ADS)

Anwaar, Aleem; Wei, Lianglinag; Guo, Hongbo; Zhang, Baopeng

2017-02-01

Plasma spray-physical vapor deposition is a new process developed to produce coatings from the vapor phase. To achieve deposition from the vapor phase, the plasma-feedstock interaction inside the plasma torch, i.e., from the powder injection point to the nozzle exit, is critical. In this work, the plasma characteristics and the momentum and heat transfer between the plasma and powder feedstock at different torch input power levels were investigated theoretically to optimize the net plasma torch power, among other important factors such as the plasma gas composition, powder feed rate, and carrier gas. The plasma characteristics were calculated using the CEA2 code, and the plasma-feedstock interaction was studied inside the torch nozzle at low-pressure (20-25 kPa) conditions. A particle dynamics model was introduced to compute the particle velocity, coupled with Xi Chen's drag model for nonevaporating particles. The results show that the energy transferred to the particles and the coating morphology are greatly influenced by the plasma gas characteristics and the particle dynamics inside the nozzle. The heat transfer between the plasma gas and feedstock material increased with the net torch power up to an optimum at 64 kW, at which a maximum of 3.4% of the available plasma energy was absorbed by the feedstock powder. Experimental results using agglomerated 7-8 wt.% yttria-stabilized zirconia (YSZ) powder as feedstock material confirmed the theoretical predictions.

Pulsed discharges produced by high-power surface waves

NASA Astrophysics Data System (ADS)

Böhle, A.; Ivanov, O.; Kolisko, A.; Kortshagen, U.; Schlüter, H.; Vikharev, A.

1996-02-01

The mechanisms of the ionization front advance in surface-wave-produced discharges are investigated using two experimental set-ups. The high-power surface waves are excited in a 3 cm wavelength band by a surfaguide and a novel type of launcher (an E-plane junction). The ionization front velocity of the surface wave is measured for a wide range of gas pressures, incident microwave power and initial pre-ionization. The experimental results are compared with theoretical ones based on three different models. The comparison between theory and experiment allows one to suggest a new interpretation of the ionization front's advance. The ionization front velocity is determined by a breakdown wave or an ionization wave in the electric field of a high-power surface wave in the zone near the ionization front.

Negative DC corona discharge current characteristics in a flowing two-phase (air + suspended smoke particles) fluid

NASA Astrophysics Data System (ADS)

Berendt, Artur; Domaszka, Magdalena; Mizeraczyk, Jerzy

2017-04-01

The electrical characteristics of a steady-state negative DC corona discharge in a two-phase fluid (air with suspended cigarette smoke particles) flowing along a chamber with a needle-to-plate electrode arrangement were experimentally investigated. The two-phase flow was transverse in respect to the needle-to-plate axis. The velocity of the transverse two-phase flow was limited to 0.8 m/s, typical of the electrostatic precipitators. We found that three discharge current modes of the negative corona exist in the two-phase (air + smoke particles) fluid: the Trichel pulses mode, the "Trichel pulses superimposed on DC component" mode and the DC component mode, similarly as in the corona discharge in air (a single-phase fluid). The shape of Trichel pulses in the air + suspended particles fluid is similar to that in air. However, the Trichel pulse amplitudes are higher than those in "pure" air while their repetition frequency is lower. As a net consequence of that the averaged corona discharge current in the two-phase fluid is lower than in "pure" air. It was also found that the average discharge current decreases with increasing suspended particle concentration. The calculations showed that the dependence of the average negative corona current (which is a macroscopic corona discharge parameter) on the particle concentration can be explained by the particle-concentration dependencies of the electric charge of Trichel pulse and the repetition frequency of Trichel pulses, both giving a microscopic insight into the electrical phenomena in the negative corona discharge. Our investigations showed also that the average corona discharge current in the two-phase fluid is almost unaffected by the transverse fluid flow up to a velocity of 0.8 m/s. Contribution to the topical issue "The 15th International Symposium on High Pressure Low Temperature Plasma Chemistry (HAKONE XV)", edited by Nicolas Gherardi and Tomáš Hoder

Study on law of negative corona discharge in microparticle-air two-phase flow media

NASA Astrophysics Data System (ADS)

He, Bo; Li, Tianwei; Xiu, Yaping; Zhao, Heng; Peng, Zongren; Meng, Yongpeng

2016-03-01

To study the basic law of negative corona discharge in solid particle-air two-phase flow, corona discharge experiments in a needle-plate electrode system at different voltage levels and different wind speed were carried out in the wind tunnel. In this paper, the change law of average current and current waveform were analyzed, and the observed phenomena were systematically explained from the perspectives of airflow, particle charging, and particle motion with the help of PIV (particle image velocity) measurements and ultraviolet observations.

A Scanning laser-velocimeter technique for measuring two-dimensional wake-vortex velocity distributions. [Langley Vortex Research Facility

NASA Technical Reports Server (NTRS)

Gartrell, L. R.; Rhodes, D. B.

1980-01-01

A rapid scanning two dimensional laser velocimeter (LV) has been used to measure simultaneously the vortex vertical and axial velocity distributions in the Langley Vortex Research Facility. This system utilized a two dimensional Bragg cell for removing flow direction ambiguity by translating the optical frequency for each velocity component, which was separated by band-pass filters. A rotational scan mechanism provided an incremental rapid scan to compensate for the large displacement of the vortex with time. The data were processed with a digital counter and an on-line minicomputer. Vaporized kerosene (0.5 micron to 5 micron particle sizes) was used for flow visualization and LV scattering centers. The overall measured mean-velocity uncertainity is less than 2 percent. These measurements were obtained from ensemble averaging of individual realizations.

A novel approach for direct estimation of fresh groundwater discharge to an estuary

USGS Publications Warehouse

Ganju, Neil K.

2011-01-01

Coastal groundwater discharge is an important source of freshwater and nutrients to coastal and estuarine systems. Directly quantifying the spatially integrated discharge of fresh groundwater over a coastline is difficult due to spatial variability and limited observational methods. In this study, I applied a novel approach to estimate net freshwater discharge from a groundwater-fed tidal creek over a spring-neap cycle, with high temporal resolution. Acoustic velocity instruments measured tidal water fluxes while other sensors measured vertical and lateral salinity to estimate cross-sectionally averaged salinity. These measurements were used in a time-dependent version of Knudsen's salt balance calculation to estimate the fresh groundwater contribution to the tidal creek. The time-series of fresh groundwater discharge shows the dependence of fresh groundwater discharge on tidal pumping, and the large difference between monthly mean discharge and instantaneous discharge over shorter timescales. The approach developed here can be implemented over timescales from days to years, in any size estuary with dominant groundwater inputs and well-defined cross-sections. The approach also directly links delivery of groundwater from the watershed with fluxes to the coastal environment. Copyright. Published in 2011 by the American Geophysical Union.

Charge exchange contamination of CRIT-II barium CIV experiment. [critical ionization velocity in ionosphere

NASA Technical Reports Server (NTRS)

Swenson, G. R.; Mende, S. B.; Meyerott, R. E.; Rairden, R. L.

1991-01-01

Experiments have been recently performed which attempted to confirm critical ionization velocity (CIV) ionization by deploying chemicals at high velocity in the ionosphere. Specifically, the CRIT-II rocket performed a barium release in the ionosphere, where observations of Ba(+) resonant emissions following the release are believed to have resulted from the CIV process. Calculations are presented which suggest a significant fraction (if not all) of the Ba(+) observed likely resulted from charge exchange with the thermosphere ions and not through CIV processes. The results presented here are pertinent to other CIV experiments performed in the ionosphere. It is recommended that laboratory measurements should be made of the charge exchange cross section between O(+) and Ba as well as other metal vapors used in CIV experiments.

Functional form for plasma velocity in a rapidly rotating tokamak discharge

DOE PAGES

Burrell, Keith H.; Chrystal, C. olin

2014-07-25

A recently developed technique using charge exchange spectroscopy determines the ion poloidal rotation in tokamak plasmas from the poloidal variation in the toroidal angular rotation speed. The basis for this technique is the functional form for the plasma velocity calculated from the equilibrium equations. The initial development of this technique utilized the functional form determined for conditions where the ion toroidal rotation speed is much smaller than the ion thermal speed. There are cases, however, where the toroidal rotation can be comparable to the ion thermal speed, especially for high atomic number impurities. Furthermore, the present paper extends the previousmore » analysis to this high rotation speed case and demonstrates how to extract the poloidal rotation speed from measurements of the toroidal angular rotation speed at two points on a flux surface.« less

Two dimensional radial gas flows in atmospheric pressure plasma-enhanced chemical vapor deposition

NASA Astrophysics Data System (ADS)

Kim, Gwihyun; Park, Seran; Shin, Hyunsu; Song, Seungho; Oh, Hoon-Jung; Ko, Dae Hong; Choi, Jung-Il; Baik, Seung Jae

2017-12-01

Atmospheric pressure (AP) operation of plasma-enhanced chemical vapor deposition (PECVD) is one of promising concepts for high quality and low cost processing. Atmospheric plasma discharge requires narrow gap configuration, which causes an inherent feature of AP PECVD. Two dimensional radial gas flows in AP PECVD induces radial variation of mass-transport and that of substrate temperature. The opposite trend of these variations would be the key consideration in the development of uniform deposition process. Another inherent feature of AP PECVD is confined plasma discharge, from which volume power density concept is derived as a key parameter for the control of deposition rate. We investigated deposition rate as a function of volume power density, gas flux, source gas partial pressure, hydrogen partial pressure, plasma source frequency, and substrate temperature; and derived a design guideline of deposition tool and process development in terms of deposition rate and uniformity.

Study on of Seepage Flow Velocity in Sand Layer Profile as Affected by Water Depth and Slope Gradience

NASA Astrophysics Data System (ADS)

Han, Z.; Chen, X.

2017-12-01

BACKGROUND: The subsurface water flow velocity is of great significance in understanding the hydrodynamic characteristics of soil seepage and the influence of interaction between seepage flow and surface runoff on the soil erosion and sediment transport process. OBJECTIVE: To propose a visualized method and equipment for determining the seepage flow velocity and measuring the actual flow velocity and Darcy velocity as well as the relationship between them.METHOD: A transparent organic glass tank is used as the test soil tank, the white river sand is used as the seepage test material and the fluorescent dye is used as the indicator for tracing water flow, so as to determine the thickness and velocity of water flow in a visualized way. Water is supplied at the same flow rate (0.84 L h-1) to the three parts with an interval of 1m at the bottom of the soil tank and the pore water velocity and the thickness of each water layer are determined under four gradient conditions. The Darcy velocity of each layer is calculated according to the water supply flow and the discharge section area. The effective discharge flow pore is estimated according to the moisture content and porosity and then the relationship between Darcy velocity and the measured velocity is calculated based on the water supply flow and the water layer thickness, and finally the correctness of the calculation results is verified. RESULTS: According to the velocity calculation results, Darcy velocity increases significantly with the increase of gradient; in the sand layer profile, the flow velocity of pore water at different depths increases with the increase of gradient; under the condition of the same gradient, the lower sand layer has the maximum flow velocity of pore water. The air-filled porosity of sand layer determines the proportional relationship between Darcy velocity and pore flow velocity. CONCLUSIONS: The actual flow velocity and Darcy velocity can be measured by a visualized method and the

Raman-Ramsey multizone spectroscopy in a pure rubidium vapor cell

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

Failache, H.; Lenci, L.; Lezama, A.

2010-02-15

In view of application to a miniaturized spectroscopy system, we consider an optical setup that splits a laser beam into several parallel narrow light sheets allowing an effective beam expansion and consequently longer atom-light interaction times. We analyze the multizone coherent population trapping (MZCPT) spectroscopy of alkali-metal-vapor atoms, without buffer gas, in the presence of a split light beam. We show that the MZCPT signal is largely insensitive to intensity broadening. Experimentally observed spectra are in qualitative agreement with the predictions of a simplified model that describes each spectrum as an integral over the atomic velocity distribution of Ramsey multizonemore » spectra.« less

Observation of copper atoms behavior in a vacuum arc discharge using laser spectroscopy

NASA Astrophysics Data System (ADS)

Sung, Y. M.; Hayashi, Y.; Okraku-Yirenkyi, Y.; Otsubo, M.; Honda, C.; Sakoda, T.

2003-01-01

In order to investigate the most important parameters influencing the breaking characteristic of a vacuum circuit breaker (VCB), the behavior of copper (Cu) particles emitted from electrodes designed as an imitation of a vacuum valve of the VCB was observed. The temporal-spatial intensity distributions due to Cu particles in an excited state or a neutral state were measured using the laser induced fluorescence (LIF) technique and a charge coupled device camera attached with a special filter. The diffusion velocity of a Cu atom was also investigated by evaluating a Doppler shift of the LIF signal. The results showed that most Cu particles were emitted from the anode and were in an excited state or an ionized state during an arc discharge. Also, Cu particles were distributed between electrodes even after the discharge chocked, and its diffusion velocity in the direction of the cathode from the anode was about 2.6 km/s.

Vapor generator wand

NASA Technical Reports Server (NTRS)

Robelen, David B. (Inventor)

1996-01-01

A device for producing a stream of vapor for wind tunnel airflow visualization is described. An electrically conductive heating tube is used to resistively heat a vapor producing liquid. The heating and delivery systems are integrated to allow the device to present a small cross section to the air flow, thereby reducing disturbances due to the device. The simplicity of the design allows for inexpensive implementation and construction. The design is readily scaled for use in various wind tunnel applications. The device may also find uses in manufacturing, producing a vapor for deposition on a substrate.

Wave propagation and noncollisional heating in neutral loop and helicon discharges

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

Celik, Y.; Crintea, D. L.; Luggenhoelscher, D.

2011-02-15

Heating mechanisms in two types of magnetized low pressure rf (13.56 MHz) discharges are investigated: a helicon discharge and a neutral loop discharge. Radial B-dot probe measurements demonstrate that the neutral loop discharge is sustained by helicon waves as well. Axial B-dot probe measurements reveal standing wave and beat patterns depending on the dc magnetic field strength and plasma density. In modes showing a strong wave damping, the plasma refractive index attains values around 100, leading to electron-wave interactions. In strongly damped modes, the radial plasma density profiles are mainly determined by power absorption of the propagating helicon wave, whereasmore » in weakly damped modes, inductive coupling dominates. Furthermore, an azimuthal diamagnetic drift is identified. Measurements of the helicon wave phase demonstrate that initial plane wave fronts are bent during their axial propagation due to the inhomogeneous density profile. A developed analytical standing wave model including Landau damping reproduces very well the damping of the axial helicon wave field. This comparison underlines the theory whereupon Landau damping of electrons traveling along the field lines at speeds close to the helicon phase velocity is the main damping mechanism in both discharges.« less

Vapor spill monitoring method

DOEpatents

Bianchini, Gregory M.; McRae, Thomas G.

1985-01-01

Method for continuous sampling of liquified natural gas effluent from a spill pipe, vaporizing the cold liquified natural gas, and feeding the vaporized gas into an infrared detector to measure the gas composition. The apparatus utilizes a probe having an inner channel for receiving samples of liquified natural gas and a surrounding water jacket through which warm water is flowed to flash vaporize the liquified natural gas.

Optimization of DIII-D discharges to avoid AE destabilization

NASA Astrophysics Data System (ADS)

Varela, Jacobo; Spong, Donald; Garcia, Luis; Huang, Juan; Murakami, Masanori

2017-10-01

The aim of the study is to analyze the stability of Alfven Eigenmodes (AE) perturbed by energetic particles (EP) during DIII-D operation. We identify the optimal NBI operational regimes that avoid or minimize the negative effects of AE on the device performance. We use the reduced MHD equations to describe the linear evolution of the poloidal flux and the toroidal component of the vorticity in a full 3D system, coupled with equations of density and parallel velocity moments for the energetic particles, including the effect of the acoustic modes. We add the Landau damping and resonant destabilization effects using a closure relation. We perform parametric studies of the MHD and AE stability, taking into account the experimental profiles of the thermal plasma and EP, also using a range of values of the energetic particles β, density and velocity as well the effect of the toroidal couplings. We reproduce the AE activity observed in high poloidal β discharge at the pedestal and reverse shear discharges. This material based on work is supported both by the U.S. Department of Energy, Office of Science, under Contract DE-AC05-00OR22725 with UT-Battelle, LLC. Research sponsored in part by the Ministerio de Economia y Competitividad of Spain under the project.

Piezoelectric trace vapor calibrator

NASA Astrophysics Data System (ADS)

Verkouteren, R. Michael; Gillen, Greg; Taylor, David W.

2006-08-01

The design and performance of a vapor generator for calibration and testing of trace chemical sensors are described. The device utilizes piezoelectric ink-jet nozzles to dispense and vaporize precisely known amounts of analyte solutions as monodisperse droplets onto a hot ceramic surface, where the generated vapors are mixed with air before exiting the device. Injected droplets are monitored by microscope with strobed illumination, and the reproducibility of droplet volumes is optimized by adjustment of piezoelectric wave form parameters. Complete vaporization of the droplets occurs only across a 10°C window within the transition boiling regime of the solvent, and the minimum and maximum rates of trace analyte that may be injected and evaporated are determined by thermodynamic principles and empirical observations of droplet formation and stability. By varying solution concentrations, droplet injection rates, air flow, and the number of active nozzles, the system is designed to deliver—on demand—continuous vapor concentrations across more than six orders of magnitude (nominally 290fg/lto1.05μg/l). Vapor pulses containing femtogram to microgram quantities of analyte may also be generated. Calibrated ranges of three explosive vapors at ng/l levels were generated by the device and directly measured by ion mobility spectrometry (IMS). These data demonstrate expected linear trends within the limited working range of the IMS detector and also exhibit subtle nonlinear behavior from the IMS measurement process.

Holographic studies of the vapor explosion of vaporizing water-in-fuel emulsion droplets

NASA Technical Reports Server (NTRS)

Sheffield, S. A.; Hess, C. F.; Trolinger, J. D.

1982-01-01

Holographic studies were performed which examined the fragmentation process during vapor explosion of a water-in-fuel (hexadecane/water) emulsion droplet. Holograms were taken at 700 to 1000 microseconds after the vapor explosion. Photographs of the reconstructed holograms reveal a wide range of fragment droplet sizes created during the explosion process. Fragment droplet diameters range from below 10 microns to over 100 microns. It is estimated that between ten thousand and a million fragment droplets can result from this extremely violent vapor explosion process. This enhanced atomization is thus expected to have a pronounced effect on vaporization processes which are present during combustion of emulsified fuels.

Habitat use by a Midwestern U.S.A. riverine fish assemblage: effects of season, water temperature and river discharge

USGS Publications Warehouse

Gillette, D.P.; Tiemann, J.S.; Edds, D.R.; Wildhaber, M.L.

2006-01-01

The hypothesis that temperate stream fishes alter habitat use in response to changing water temperature and stream discharge was evaluated over a 1 year period in the Neosho River, Kansas, U.S.A. at two spatial scales. Winter patterns differed from those of all other seasons, with shallower water used less frequently, and low-flow habitat more frequently, than at other times. Non-random habitat use was more frequent at the point scale (4.5 m2) than at the larger reach scale (20-40 m), although patterns at both scales were similar. Relative to available habitats, assemblages used shallower, swifter-flowing water as temperature increased, and shallower, slower-flowing water as river discharge increased. River discharge had a stronger effect on assemblage habitat use than water temperature. Proportion of juveniles in the assemblage did not have a significant effect. This study suggests that many riverine fishes shift habitats in response to changing environmental conditions, and supports, at the assemblage level, the paradigm of lotic fishes switching from shallower, high-velocity habitats in summer to deeper, low-velocity habitats in winter, and of using shallower, low-velocity habitats during periods of high discharge. Results also indicate that different species within temperate river fish assemblages show similar habitat use patterns at multiple scales in response to environmental gradients, but that non-random use of available habitats is more frequent at small scales. ?? 2006 The Fisheries Society of the British Isles.

Large-volume excitation of air, argon, nitrogen and combustible mixtures by thermal jets produced by nanosecond spark discharges

NASA Astrophysics Data System (ADS)

Stepanyan, Sergey; Hayashi, Jun; Salmon, Arthur; Stancu, Gabi D.; Laux, Christophe O.

2017-04-01

This work presents experimental observations of strong expanding thermal jets following the application of nanosecond spark discharges. These jets propagate in a toroidal shape perpendicular to the interelectrode axis, with high velocities of up to 30 m s-1 and over distances of the order of a cm. Their propagation length is much larger than the thermal expansion region produced by the conventional millisecond sparks used in car engine ignition, thus greatly improving the volumetric excitation of gas mixtures. The shape and velocity of the jets is found to be fairly insensitive to the shape of the electrodes. In addition, their spatial extent is found to increase with the number of nanosecond sparks and with the discharge voltage, and to decrease slightly with the pressure between 1 and 7 atm at constant applied voltage. Finally, this thermal jet phenomenon is observed in experiments conducted with many types of gas mixtures, including air, nitrogen, argon, and combustible CH4/air mixtures. This makes nanosecond repetitively pulsed discharges particularly attractive for aerodynamic flow control or plasma-assisted combustion because of their ability to excite large volumes of gas, typically about 100 times the volume of the discharge.

Correcting acoustic Doppler current profiler discharge measurement bias from moving-bed conditions without global positioning during the 2004 Glen Canyon Dam controlled flood on the Colorado River

USGS Publications Warehouse

Gartner, J.W.; Ganju, N.K.

2007-01-01

Discharge measurements were made by acoustic Doppler current profiler at two locations on the Colorado River during the 2004 controlled flood from Glen Canyon Dam, Arizona. Measurement hardware and software have constantly improved from the 1980s such that discharge measurements by acoustic profiling instruments are now routinely made over a wide range of hydrologic conditions. However, measurements made with instruments deployed from moving boats require reliable boat velocity data for accurate measurements of discharge. This is normally accomplished by using special acoustic bottom track pings that sense instrument motion over bottom. While this method is suitable for most conditions, high current flows that produce downstream bed sediment movement create a condition known as moving bed that will bias velocities and discharge to lower than actual values. When this situation exists, one solution is to determine boat velocity with satellite positioning information. Another solution is to use a lower frequency instrument. Discharge measurements made during the 2004 Glen Canyon controlled flood were subject to moving-bed conditions and frequent loss of bottom track. Due to site conditions and equipment availability, the measurements were conducted without benefit of external positioning information or lower frequency instruments. This paper documents and evaluates several techniques used to correct the resulting underestimated discharge measurements. One technique produces discharge values in good agreement with estimates from numerical model and measured hydrographs during the flood. ?? 2007, by the American Society of Limnology and Oceanography, Inc.

Static gas-liquid interfacial direct current discharge plasmas using ionic liquid cathode

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

Kaneko, T.; CREST/JST, Tokyo 102-0075; Baba, K.

Due to the unique properties of ionic liquids such as their extremely low vapor pressure and high heat capacity, we have succeeded in creating the static and stable gas (plasmas)-liquid (ionic liquids) interfacial field using a direct current discharge under a low gas pressure condition. It is clarified that the ionic liquid works as a nonmetal liquid electrode, and furthermore, a secondary electron emission coefficient of the ionic liquid is larger than that of conventional metal electrodes. The plasma potential structure of the gas-liquid interfacial region, and resultant interactions between the plasma and the ionic liquid are revealed by changingmore » a polarity of the electrode in the ionic liquid. By utilizing the ionic liquid as a cathode electrode, the positive ions in the plasma region are found to be irradiated to the ionic liquid. This ion irradiation causes physical and chemical reactions at the gas-liquid interfacial region without the vaporization of the ionic liquid.« less

Pulsed electromagnetic gas accelleration. [incorporation of hollow cathode in plasma discharge and suitability determination of MPD discharge as plasmadynamic laser source

NASA Technical Reports Server (NTRS)

Jahn, R. G.

1973-01-01

Direct measurement with thermocouples of the power deposited in the anode of a multi-megawatt magnetoplasmadynamic discharge has shown the fractional anode power to decrease from 50% at 200 kW to 10% at 20 MW. Using local measurements of current density, electric potential, and electron temperature, the traditional model for heat conduction to the anode is found to be inadequate. Other experiments in which the voltage-current characteristics and exhaust velocities of MPD arcs using Plexiglas and boron nitride chamber insulators and various mass injection configurations show that ablation can affect nominal accelerator operation in several distinct ways. The incorporation of a hollow cathode in a 7 kA plasma discharge has shown that a stable current attachment can be realized in the cavity without the aid of cathode heaters, keeper electrodes, or emissive coatings.

Wind tunnel experiments on flow separation control of an Unmanned Air Vehicle by nanosecond discharge plasma aerodynamic actuation

NASA Astrophysics Data System (ADS)

Kang, Chen; Hua, Liang

2016-02-01

Plasma flow control (PFC) is a new kind of active flow control technology, which can improve the aerodynamic performances of aircrafts remarkably. The flow separation control of an unmanned air vehicle (UAV) by nanosecond discharge plasma aerodynamic actuation (NDPAA) is investigated experimentally in this paper. Experimental results show that the applied voltages for both the nanosecond discharge and the millisecond discharge are nearly the same, but the current for nanosecond discharge (30 A) is much bigger than that for millisecond discharge (0.1 A). The flow field induced by the NDPAA is similar to a shock wave upward, and has a maximal velocity of less than 0.5 m/s. Fast heating effect for nanosecond discharge induces shock waves in the quiescent air. The lasting time of the shock waves is about 80 μs and its spread velocity is nearly 380 m/s. By using the NDPAA, the flow separation on the suction side of the UAV can be totally suppressed and the critical stall angle of attack increases from 20° to 27° with a maximal lift coefficient increment of 11.24%. The flow separation can be suppressed when the discharge voltage is larger than the threshold value, and the optimum operation frequency for the NDPAA is the one which makes the Strouhal number equal one. The NDPAA is more effective than the millisecond discharge plasma aerodynamic actuation (MDPAA) in boundary layer flow control. The main mechanism for nanosecond discharge is shock effect. Shock effect is more effective in flow control than momentum effect in high speed flow control. Project supported by the National Natural Science Foundation of China (Grant Nos. 61503302, 51207169, and 51276197), the China Postdoctoral Science Foundation (Grant No. 2014M562446), and the Natural Science Foundation of Shaanxi Province, China (Grant No. 2015JM1001).

Organic solids produced by electrical discharge in reducing atmospheres - Tholin molecular analysis

NASA Technical Reports Server (NTRS)

Khare, B. N.; Sagan, C.; Zumberge, J. E.; Sklarew, D. S.; Nagy, B.

1981-01-01

The complex dark brown solid of a class called tholins, produced on passage of an electrical discharge through a roughly equimolar mixture of methane and ammonia with 2.6% water vapor, is analyzed by vacuum pyrolysis followed by gas chromatography and mass spectrometry. Pyrolyzates include a wide range of aliphatic and aromatic nitriles, alkanes, alkenes, aromatic hydrocarbons, pyrrole, and pyridine. This tholin is remarkably stable to 950 C. It and its degradation products are candidate constituents of planetary aerosols in the outer solar system and of the grains in the interstellar medium.

Measurements of neutral and ion velocity distribution functions in a Hall thruster

NASA Astrophysics Data System (ADS)

Svarnas, Panagiotis; Romadanov, Iavn; Diallo, Ahmed; Raitses, Yevgeny

2015-11-01

Hall thruster is a plasma device for space propulsion. It utilizes a cross-field discharge to generate a partially ionized weakly collisional plasma with magnetized electrons and non-magnetized ions. The ions are accelerated by the electric field to produce the thrust. There is a relatively large number of studies devoted to characterization of accelerated ions, including measurements of ion velocity distribution function using laser-induced fluorescence diagnostic. Interactions of these accelerated ions with neutral atoms in the thruster and the thruster plume is a subject of on-going studies, which require combined monitoring of ion and neutral velocity distributions. Herein, laser-induced fluorescence technique has been employed to study neutral and single-charged ion velocity distribution functions in a 200 W cylindrical Hall thruster operating with xenon propellant. An optical system is installed in the vacuum chamber enabling spatially resolved axial velocity measurements. The fluorescence signals are well separated from the plasma background emission by modulating the laser beam and using lock-in detectors. Measured velocity distribution functions of neutral atoms and ions at different operating parameters of the thruster are reported and analyzed. This work was supported by DOE contract DE-AC02-09CH11466.

Slope-velocity equilibrium and evolution of surface roughness on a stony hillslope

NASA Astrophysics Data System (ADS)

Nearing, Mark A.; Polyakov, Viktor O.; Nichols, Mary H.; Hernandez, Mariano; Li, Li; Zhao, Ying; Armendariz, Gerardo

2017-06-01

Slope-velocity equilibrium is hypothesized as a state that evolves naturally over time due to the interaction between overland flow and surface morphology, wherein steeper areas develop a relative increase in physical and hydraulic roughness such that flow velocity is a unique function of overland flow rate independent of slope gradient. This study tests this hypothesis under controlled conditions. Artificial rainfall was applied to 2 m by 6 m plots at 5, 12, and 20 % slope gradients. A series of simulations were made with two replications for each treatment with measurements of runoff rate, velocity, rock cover, and surface roughness. Velocities measured at the end of each experiment were a unique function of discharge rates, independent of slope gradient or rainfall intensity. Physical surface roughness was greater at steeper slopes. The data clearly showed that there was no unique hydraulic coefficient for a given slope, surface condition, or rainfall rate, with hydraulic roughness greater at steeper slopes and lower intensities. This study supports the hypothesis of slope-velocity equilibrium, implying that use of hydraulic equations, such as Chezy and Manning, in hillslope-scale runoff models is problematic because the coefficients vary with both slope and rainfall intensity.

SOFIA Water Vapor Monitor Design

NASA Technical Reports Server (NTRS)

Cooper, R.; Roellig, T. L.; Yuen, L.; Shiroyama, B.; Meyer, A.; Devincenzi, D. (Technical Monitor)

2002-01-01

The SOFIA Water Vapor Monitor (WVM) is a heterodyne radiometer designed to determine the integrated amount of water vapor along the telescope line of sight and directly to the zenith. The basic technique that was chosen for the WVM uses radiometric measurements of the center and wings of the 183.3 GHz rotational line of water to measure the water vapor. The WVM reports its measured water vapor levels to the aircraft Mission Controls and Communication System (MCCS) while the SOFIA observatory is in normal operation at flight altitude. The water vapor measurements are also available to other scientific instruments aboard the observatory. The electrical, mechanical and software design of the WVM are discussed.

Non-Ballistic Vapor-Driven Ejecta

NASA Technical Reports Server (NTRS)

Wrobel, K. E.; Schultz, P. H.; Heineck, J. T.

2004-01-01

Impact-induced vaporization is a key component of early-time cratering mechanics. Previous experimental [1,2] and computational [e.g., 3] studies focused on the generation and expansion of vapor clouds in an attempt to better understand vaporization in hypervelocity impacts. Presented here is a new experimental approach to the study of impact-induced vaporization. The three-dimensional particle image velocimetry (3D PIV) system captures interactions between expanding vapor phases and fine particulates. Particles ejected early in the cratering process may be entrained in expanding gas phases generated at impact, altering their otherwise ballistic path of flight. 3D PIV allows identifying the presence of such non-ballistic ejecta from very early times in the cratering process.

Synthetic Graphene Oxide Leaf for Solar Desalination with Zero Liquid Discharge.

PubMed

Finnerty, Casey; Zhang, Lei; Sedlak, David L; Nelson, Kara L; Mi, Baoxia

2017-10-17

Water vapor generation through sunlight harvesting and heat localization by carbon-based porous thin film materials holds great promise for sustainable, energy-efficient desalination and water treatment. However, the applicability of such materials in a high-salinity environment emphasizing zero-liquid-discharge brine disposal has not been studied. This paper reports the characterization and evaporation performance of a nature-inspired synthetic leaf made of graphene oxide (GO) thin film material, which exhibited broadband light absorption and excellent stability in high-salinity water. Under 0.82-sun illumination (825 W/m 2 ), a GO leaf floating on water generated steam at a rate of 1.1 L per m 2 per hour (LMH) with a light-to-vapor energy conversion efficiency of 54%, while a GO leaf lifted above water in a tree-like configuration generated steam at a rate of 2.0 LMH with an energy efficiency of 78%. The evaporation rate increased with increasing light intensity and decreased with increasing salinity. During a long-term evaporation experiment with a 15 wt % NaCl solution, the GO leaf demonstrated stable performance despite gradual and eventually severe accumulation of salt crystals on the leaf surface. Furthermore, the GO leaf can be easily restored to its pristine condition by simply scraping off salt crystals from its surface and rinsing with water. Therefore, the robust high performance and relatively low fabrication cost of the synthetic GO leaf could potentially unlock a new generation of desalination technology that can be entirely solar-powered and achieve zero liquid discharge.

Decomposition of toluene in a steady-state atmospheric-pressure glow discharge

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

Trushkin, A. N.; Grushin, M. E.; Kochetov, I. V.

Results are presented from experimental studies of decomposition of toluene (C{sub 6}H{sub 5}CH{sub 3}) in a polluted air flow by means of a steady-state atmospheric pressure glow discharge at different water vapor contents in the working gas. The experimental results on the degree of C{sub 6}H{sub 5}CH{sub 3} removal are compared with the results of computer simulations conducted in the framework of the developed kinetic model of plasma chemical decomposition of toluene in the N{sub 2}: O{sub 2}: H{sub 2}O gas mixture. A substantial influence of the gas flow humidity on toluene decomposition in the atmospheric pressure glow discharge ismore » demonstrated. The main mechanisms of the influence of humidity on C{sub 6}H{sub 5}CH{sub 3} decomposition are determined. The existence of two stages in the process of toluene removal, which differ in their duration and the intensity of plasma chemical decomposition of C{sub 6}H{sub 5}CH{sub 3} is established. Based on the results of computer simulations, the composition of the products of plasma chemical reactions at the output of the reactor is analyzed as a function of the specific energy deposition and gas flow humidity. The existence of a catalytic cycle in which hydroxyl radical OH acts a catalyst and which substantially accelerates the recombination of oxygen atoms and suppression of ozone generation when the plasma-forming gas contains water vapor is established.« less

21 CFR 868.5880 - Anesthetic vaporizer.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Anesthetic vaporizer. 868.5880 Section 868.5880...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5880 Anesthetic vaporizer. (a) Identification. An anesthetic vaporizer is a device used to vaporize liquid anesthetic and deliver a controlled...

21 CFR 868.5880 - Anesthetic vaporizer.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Anesthetic vaporizer. 868.5880 Section 868.5880...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5880 Anesthetic vaporizer. (a) Identification. An anesthetic vaporizer is a device used to vaporize liquid anesthetic and deliver a controlled...

21 CFR 868.5880 - Anesthetic vaporizer.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Anesthetic vaporizer. 868.5880 Section 868.5880...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5880 Anesthetic vaporizer. (a) Identification. An anesthetic vaporizer is a device used to vaporize liquid anesthetic and deliver a controlled...

21 CFR 868.5880 - Anesthetic vaporizer.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Anesthetic vaporizer. 868.5880 Section 868.5880...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5880 Anesthetic vaporizer. (a) Identification. An anesthetic vaporizer is a device used to vaporize liquid anesthetic and deliver a controlled...

21 CFR 868.5880 - Anesthetic vaporizer.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Anesthetic vaporizer. 868.5880 Section 868.5880...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5880 Anesthetic vaporizer. (a) Identification. An anesthetic vaporizer is a device used to vaporize liquid anesthetic and deliver a controlled...

Determining the Discharge Rate from a Submerged Oil Leaks using ROV Video and CFD study

NASA Astrophysics Data System (ADS)

Saha, Pankaj; Shaffer, Frank; Shahnam, Mehrdad; Savas, Omer; Devites, Dave; Steffeck, Timothy

2016-11-01

The current paper reports a technique to measure the discharge rate by analyzing the video from a Remotely Operated Vehicle (ROV). The technique uses instantaneous images from ROV video to measure the velocity of visible features (turbulent eddies) along the boundary of an oil leak jet and subsequently classical theory of turbulent jets is imposed to determine the discharge rate. The Flow Rate Technical Group (FRTG) Plume Team developed this technique that manually tracked the visible features and produced the first accurate government estimates of the oil discharge rate from the Deepwater Horizon (DWH). For practical application this approach needs automated control. Experiments were conducted at UC Berkeley and OHMSETT that recorded high speed, high resolution video of submerged dye-colored water or oil jets and subsequently, measured the velocity data employing LDA and PIV software. Numerical simulation have been carried out using experimental submerged turbulent oil jets flow conditions employing LES turbulence closure and VOF interface capturing technique in OpenFOAM solver. The CFD results captured jet spreading angle and jet structures in close agreement with the experimental observations. The work was funded by NETL and DOI Bureau of Safety and Environmental Enforcement (BSEE).

The transition mechanisms of the E to H mode and the H to E mode in an inductively coupled argon-mercury mixture discharge

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

Zhang, Xiao; Yu, Peng-Cheng; Liu, Yu

2015-10-15

In our experiment, the transition points between the two operational modes of capacitive coupling (E mode) and inductive coupling (H mode) were investigated at a wide range of mercury vapor pressures in an inductively coupled plasma, varying with the input radio-frequency powers and the total filling pressures (10 Pa–30 Pa). The electron temperatures were calculated versus with the mercury vapor pressures for different values of the total filling pressures. The transition power points and electron density also were measured in this study. It is shown that the transition powers, whether the E to H mode transition or the H to E modemore » transition, are lower than that of the argon discharge, and these powers almost increase with the mercury vapor pressure rising. However, the transition electron density follows an inverse relationship with the mercury vapor pressures compared with the transition powers. In addition, at the lower pressures and higher mercury vapor pressures, an inverse hysteresis was observed clearly, which did not appear in the argon gas plasma. We suggest that all these results are attributed to the electron-neutral collision frequency changed with the additional mercury vapor pressures.« less

Acoustic velocity meter systems

USGS Publications Warehouse

Laenen, Antonius

1985-01-01

Acoustic velocity meter (AVM) systems operate on the principles that the point-to-point upstream traveltime of an acoustic pulse is longer than the downstream traveltime and that this difference in traveltime can be accurately measured by electronic devices. An AVM system is capable of recording water velocity (and discharge) under a wide range of conditions, but some constraints apply: 1. Accuracy is reduced and performance is degraded if the acoustic path is not a continuous straight line. The path can be bent by reflection if it is too close to a stream boundary or by refraction if it passes through density gradients resulting from variations in either water temperature or salinity. For paths of less than 100 m, a temperature gradient of 0.1' per meter causes signal bending less than 0.6 meter at midchannel, and satisfactory velocity results can be obtained. Reflection from stream boundaries can cause signal cancellation if boundaries are too close to signal path. 2. Signal strength is attenuated by particles or bubbles that absorb, spread, or scatter sound. The concentration of particles or bubbles that can be tolerated is a function of the path length and frequency of the acoustic signal. 3. Changes in streamline orientation can affect system accuracy if the variability is random. 4. Errors relating to signal resolution are much larger for a single threshold detection scheme than for multiple threshold schemes. This report provides methods for computing the effect of various conditions on the accuracy of a record obtained from an AVM. The equipment must be adapted to the site. Field reconnaissance and preinstallation analysis to detect possible problems are critical for proper installation and operation of an AVM system.

Partitioning the effects of Global Warming on the Hydrological Cycle with Stable Isotopes in Water Vapor

NASA Astrophysics Data System (ADS)

Dee, S. G.; Russell, J. M.; Nusbaumer, J. M.; Konecky, B. L.; Buenning, N. H.; Lee, J. E.; Noone, D.

2016-12-01

General circulation models (GCMs) suggest that much of the global hydrological cycle's response to anthropogenic warming will be caused by increased lower-tropospheric water vapor concentrations and associated feedbacks. However, fingerprinting changes in the global hydrological cycle due to anthropogenic warming remains challenging. Held and Soden (2006) predicted that as lower-tropospheric water vapor increases, atmospheric circulation will weaken as climate warms to maintain the surface energy budget. Unfortunately, the strength of this feedback and the fallout for other branches of the hydrological cycle is difficult to constrain in situ or with GCMs alone. We demonstrate the utility of stable hydrogen isotope ratios in atmospheric water vapor to quantitatively trace changes in atmospheric circulation and convective mass flux in a warming world. We compare water isotope-enabled GCM experiments for control (present-day) CO2 vs. high CO2(2x, 4x) atmospheres in two GCMs, IsoGSM and iCAM5. We evaluate changes in the distribution of water vapor, vertical velocity (omega), and the stream function between these experiments in order to identify spatial patterns of circulation change over the tropical Pacific (where vertical motion is strong) and map the δD of water vapor associated with atmospheric warming. We also probe the simulations to isolate isotopic signatures associated with water vapor residence time, precipitation efficiency, divergence, and cloud physics. We show that there are robust mechanisms that moisten the troposphere and weaken convective mass flux, and that these mechanisms can be tracked using the δD of water vapor. Further, we find that these responses are most pronounced in the upper troposphere. These findings provide a framework to develop new metrics for the detection of global warming impacts to the hydrological cycle. Further, currently available satellite missions measure δD in the atmospheric boundary layer, the free atmosphere, or the

Wall ablation of heated compound-materials into non-equilibrium discharge plasmas

NASA Astrophysics Data System (ADS)

Wang, Weizong; Kong, Linghan; Geng, Jinyue; Wei, Fuzhi; Xia, Guangqing

2017-02-01

The discharge properties of the plasma bulk flow near the surface of heated compound-materials strongly affects the kinetic layer parameters modeled and manifested in the Knudsen layer. This paper extends the widely used two-layer kinetic ablation model to the ablation controlled non-equilibrium discharge due to the fact that the local thermodynamic equilibrium (LTE) approximation is often violated as a result of the interaction between the plasma and solid walls. Modifications to the governing set of equations, to account for this effect, are derived and presented by assuming that the temperature of the electrons deviates from that of the heavy particles. The ablation characteristics of one typical material, polytetrafluoroethylene (PTFE) are calculated with this improved model. The internal degrees of freedom as well as the average particle mass and specific heat ratio of the polyatomic vapor, which strongly depends on the temperature, pressure and plasma non-equilibrium degree and plays a crucial role in the accurate determination of the ablation behavior by this model, are also taken into account. Our assessment showed the significance of including such modifications related to the non-equilibrium effect in the study of vaporization of heated compound materials in ablation controlled arcs. Additionally, a two-temperature magneto-hydrodynamic (MHD) model accounting for the thermal non-equilibrium occurring near the wall surface is developed and applied into an ablation-dominated discharge for an electro-thermal chemical launch device. Special attention is paid to the interaction between the non-equilibrium plasma and the solid propellant surface. Both the mass exchange process caused by the wall ablation and plasma species deposition as well as the associated momentum and energy exchange processes are taken into account. A detailed comparison of the results of the non-equilibrium model with those of an equilibrium model is presented. The non-equilibrium results

Critical ionization velocity experiments in space

NASA Astrophysics Data System (ADS)

Lai, Shu T.; Murad, Edmond

1989-07-01

Space experiments to test the critical ionization velocity (CIV) theory have, on the whole, yielded negative results, with two notable exceptions. The results of all the experiments are analyzed with a view towards either optimizing or drawing conclusions about the conditions which lead to the propagation of CIV. In particular, four aspects of the conditions are considered: (1) beam injection angle with the ambient magnetic field in the ionosphere; (2) length of a CIV discharge region in a conical beam; (3) collisional ionization of the neutrals; and (4) chemiionization processes. The analysis leads to the conclusion that using the exhaust of the Shuttle engines may be the best way for testing CIV.

Total and settling velocity-fractionated pollution potential of sewer sediments in Jiaxing, China.

PubMed

Zhou, Yongchao; Zhang, Ping; Zhang, Yiping; Li, Jin; Zhang, Tuqiao; Yu, Tingchao

2017-10-01

Sewer sediments and their associated contaminant released along with wet-weather discharges pose potential pollution risks to environment. This paper presents total characteristics of sediments collected from Jiaxing, China. Size distribution and concentrations of volatile solids (VS) and four metals (Pb, Cu, Zn, Cr) of sediment samples from seven land use categories were analyzed. Then, the sediment samples were graded five fractions according to its settling velocity through the custom-built settling velocity-grading device. Sediment mass and pollution load distribution based on settling velocity were also assessed. The results show that there are relatively high level of heavy metal load in the sediment of separated storm drainage systems in Jiaxing, especially for the catchment of residential area (RA), road of developed area (RDA), and industrial area (IA). Although grain size follows a trend of increasing along with settling velocity, the methods of settling velocity grading are meaningful for stormwater treatment facilities with precipitation. For all land use categories, the pollution concentrations of the three lower settling velocity-fractionated sediment are relatively consistent and higher than others. Combined with mass distribution, the pollution percentage of fraction with different velocities for seven land use categories were also evaluated. Based on it, the statistical conclusion of design target settling velocity to different pollution load removal rates are drawn, which is helpful to guide design of on-site precipitation separation facilities.

Quantifying acoustic doppler current profiler discharge uncertainty: A Monte Carlo based tool for moving-boat measurements

USGS Publications Warehouse

Mueller, David S.

2017-01-01

This paper presents a method using Monte Carlo simulations for assessing uncertainty of moving-boat acoustic Doppler current profiler (ADCP) discharge measurements using a software tool known as QUant, which was developed for this purpose. Analysis was performed on 10 data sets from four Water Survey of Canada gauging stations in order to evaluate the relative contribution of a range of error sources to the total estimated uncertainty. The factors that differed among data sets included the fraction of unmeasured discharge relative to the total discharge, flow nonuniformity, and operator decisions about instrument programming and measurement cross section. As anticipated, it was found that the estimated uncertainty is dominated by uncertainty of the discharge in the unmeasured areas, highlighting the importance of appropriate selection of the site, the instrument, and the user inputs required to estimate the unmeasured discharge. The main contributor to uncertainty was invalid data, but spatial inhomogeneity in water velocity and bottom-track velocity also contributed, as did variation in the edge velocity, uncertainty in the edge distances, edge coefficients, and the top and bottom extrapolation methods. To a lesser extent, spatial inhomogeneity in the bottom depth also contributed to the total uncertainty, as did uncertainty in the ADCP draft at shallow sites. The estimated uncertainties from QUant can be used to assess the adequacy of standard operating procedures. They also provide quantitative feedback to the ADCP operators about the quality of their measurements, indicating which parameters are contributing most to uncertainty, and perhaps even highlighting ways in which uncertainty can be reduced. Additionally, QUant can be used to account for self-dependent error sources such as heading errors, which are a function of heading. The results demonstrate the importance of a Monte Carlo method tool such as QUant for quantifying random and bias errors when

High-velocity facial gunshot wounds: multidisciplinary care from prehospital to discharge

PubMed Central

Sinnott, J D; Morris, G; Medland, P J; Porter, K

2016-01-01

A case is presented in which a high velocity rifle (shotgun) was fired into the inferior part of a patient's face in an attempted suicide causing widespread trauma to the inferior and left side of the patient's face. He presented to his general practitioner where an ambulance was called. The patient is followed from prehospital care (air ambulance) to resuscitation in accident and emergency and through the first stages of reconstructive surgery. The article focuses on the multidisciplinary approach to the patient's prehospital care and initial resuscitation at a major trauma centre. CT reconstruction images of the patient's skull allow visualisation of the extent of bone damage at presentation. Medical photography allows visualisation of the extent of the initial damage and shows how reconstructive surgery was undertaken early and in progressive stages. A literature review was performed allowing discussion of the current evidence and best practice in the management of facial gunshot wounds. PMID:26823355

High-velocity facial gunshot wounds: multidisciplinary care from prehospital to discharge.

PubMed

Sinnott, J D; Morris, G; Medland, P J; Porter, K

2016-01-28

A case is presented in which a high velocity rifle (shotgun) was fired into the inferior part of a patient's face in an attempted suicide causing widespread trauma to the inferior and left side of the patient's face. He presented to his general practitioner where an ambulance was called. The patient is followed from prehospital care (air ambulance) to resuscitation in accident and emergency and through the first stages of reconstructive surgery. The article focuses on the multidisciplinary approach to the patient's prehospital care and initial resuscitation at a major trauma centre. CT reconstruction images of the patient's skull allow visualisation of the extent of bone damage at presentation. Medical photography allows visualisation of the extent of the initial damage and shows how reconstructive surgery was undertaken early and in progressive stages. A literature review was performed allowing discussion of the current evidence and best practice in the management of facial gunshot wounds. 2016 BMJ Publishing Group Ltd.

Soil vapor extraction and bioventing: Applications, limitations, and future research directions

NASA Astrophysics Data System (ADS)

Rathfelder, K.; Lang, J. R.; Abriola, L. M.

1995-07-01

Soil vapor extraction (SVE) has evolved over the past decade as an attractive in situ remediation method for unsaturated soils contaminated with volatile organic compounds (VOCs). SVE involves the generation of air flow through the pores of the contaminated soil to induce transfer of VOCs to the air stream. Air flow is established by pumping from vadose zone wells through which contaminant vapors are collected and transported above ground where they are treated, if required, and discharged to the atmosphere. The popularity of SVE technologies stems from their proven effectiveness for removing large quantities of VOCs from the soil, their cost competitiveness, and their relatively simple non-intrusive implementation. Widespread field application of SVE has occurred following the success of early laboratory and field scale feasibility studies [Texas Research Institute, 1980, 1984; Thornton and Wootan, 1982; Marley and Hoag, 1984; Crow et al., 1985, 1987]. As many as 18% of Superfund sites employ SVE remediation technologies [Travis and Macinnis, 1992] and numerous articles and reports have documented the application of SVE [e.g. Hutzler et al., 1989; Downey and Elliott, 1990; U.S. EPA, 1991; Sanderson et al, 1993; Gerbasi and Menoli, 1994; McCann et al., 1994;].

Energy distribution functions of kilovolt ions parallel and perpendicular to the magnetic field of a modified Penning discharge

NASA Technical Reports Server (NTRS)

Roth, R. J.

1973-01-01

The distribution function of ion energy parallel to the magnetic field of a modified Penning discharge has been measured with a retarding potential energy analyzer. These ions escaped through one of the throats of the magnetic mirror geometry. Simultaneous measurements of the ion energy distribution function perpendicular to the magnetic field have been made with a charge exchange neutral detector. The ion energy distribution functions are approximately Maxwellian, and the parallel and perpendicular kinetic temperatures are equal within experimental error. These results suggest that turbulent processes previously observed in this discharge Maxwellianize the velocity distribution along a radius in velocity space and cause an isotropic energy distribution. When the distributions depart from Maxwellian, they are enhanced above the Maxwellian tail.

AMTEC vapor-vapor series connected cells

NASA Technical Reports Server (NTRS)

Underwood, Mark L. (Inventor); Williams, Roger M. (Inventor); Ryan, Margaret A. (Inventor); Nakamura, Barbara J. (Inventor); Oconnor, Dennis E. (Inventor)

1995-01-01

An alkali metal thermoelectric converter (AMTEC) having a plurality of cells structurally connected in series to form a septum dividing a plenum into two chambers, and electrically connected in series, is provided with porous metal anodes and porous metal cathodes in the cells. The cells may be planar or annular, and in either case a metal alkali vapor at a high temperature is provided to the plenum through one chamber on one side of the wall and returned to a vapor boiler after condensation at a chamber on the other side of the wall in the plenum. If the cells are annular, a heating core may be placed along the axis of the stacked cells. This arrangement of series-connected cells allows efficient generation of power at high voltage and low current.

Testing the limits of the Maxwell distribution of velocities for atoms flying nearly parallel to the walls of a thin cell.

PubMed

Todorov, Petko; Bloch, Daniel

2017-11-21

For a gas at thermal equilibrium, it is usually assumed that the velocity distribution follows an isotropic 3-dimensional Maxwell-Boltzmann (M-B) law. This assumption classically implies the assumption of a "cos θ" law for the flux of atoms leaving the surface. Actually, such a law has no grounds in surface physics, and experimental tests of this assumption have remained very few. In a variety of recently developed sub-Doppler laser spectroscopy techniques for gases one-dimensionally confined in a thin cell, the specific contribution of atoms moving nearly parallel to the boundary of the vapor container becomes essential. We report here on the implementation of an experiment to probe effectively the distribution of atomic velocities parallel to the windows for a thin (60 μm) Cs vapor cell. The principle of the setup relies on a spatially separated pump-probe experiment, where the variations of the signal amplitude with the pump-probe separation provide the information on the velocity distribution. The experiment is performed in a sapphire cell on the Cs resonance line, which benefits from a long-lived hyperfine optical pumping. Presently, we can analyze specifically the density of atoms with slow normal velocities ∼5-20 m/s, already corresponding to unusual grazing flight-at ∼85°-88.5° from the normal to the surface-and no deviation from the M-B law is found within the limits of our elementary setup. Finally we suggest tracks to explore more parallel velocities, when surface details-roughness or structure-and the atom-surface interaction should play a key role to restrict the applicability of an M-B-type distribution.

Testing the limits of the Maxwell distribution of velocities for atoms flying nearly parallel to the walls of a thin cell

NASA Astrophysics Data System (ADS)

Todorov, Petko; Bloch, Daniel

2017-11-01

For a gas at thermal equilibrium, it is usually assumed that the velocity distribution follows an isotropic 3-dimensional Maxwell-Boltzmann (M-B) law. This assumption classically implies the assumption of a "cos θ" law for the flux of atoms leaving the surface. Actually, such a law has no grounds in surface physics, and experimental tests of this assumption have remained very few. In a variety of recently developed sub-Doppler laser spectroscopy techniques for gases one-dimensionally confined in a thin cell, the specific contribution of atoms moving nearly parallel to the boundary of the vapor container becomes essential. We report here on the implementation of an experiment to probe effectively the distribution of atomic velocities parallel to the windows for a thin (60 μm) Cs vapor cell. The principle of the setup relies on a spatially separated pump-probe experiment, where the variations of the signal amplitude with the pump-probe separation provide the information on the velocity distribution. The experiment is performed in a sapphire cell on the Cs resonance line, which benefits from a long-lived hyperfine optical pumping. Presently, we can analyze specifically the density of atoms with slow normal velocities ˜5-20 m/s, already corresponding to unusual grazing flight—at ˜85°-88.5° from the normal to the surface—and no deviation from the M-B law is found within the limits of our elementary setup. Finally we suggest tracks to explore more parallel velocities, when surface details—roughness or structure—and the atom-surface interaction should play a key role to restrict the applicability of an M-B-type distribution.

Reactions of Microsolvated Organic Compounds at Ambient Surfaces: Droplet Velocity, Charge State, and Solvent Effects

NASA Astrophysics Data System (ADS)

Badu-Tawiah, Abraham K.; Campbell, Dahlia I.; Cooks, R. Graham

2012-06-01

The exposure of charged microdroplets containing organic ions to solid-phase reagents at ambient surfaces results in heterogeneous ion/surface reactions. The electrosprayed droplets were driven pneumatically in ambient air and then electrically directed onto a surface coated with reagent. Using this reactive soft landing approach, acid-catalyzed Girard condensation was achieved at an ambient surface by directing droplets containing Girard T ions onto a dry keto-steroid. The charged droplet/surface reaction was much more efficient than the corresponding bulk solution-phase reaction performed on the same scale. The increase in product yield is ascribed to solvent evaporation, which causes moderate pH values in the starting droplet to reach extreme values and increases reagent concentrations. Comparisons are made with an experiment in which the droplets were pneumatically accelerated onto the ambient surface (reactive desorption electrospray ionization, DESI). The same reaction products were observed but differences in spatial distribution were seen associated with the "splash" of the high velocity DESI droplets. In a third type of experiment, the reactions of charged droplets with vapor phase reagents were examined by allowing electrosprayed droplets containing a reagent to intercept the headspace vapor of an analyte. Deposition onto a collector surface and mass analysis showed that samples in the vapor phase were captured by the electrospray droplets, and that instantaneous derivatization of the captured sample is possible in the open air. The systems examined under this condition included the derivatization of cortisone vapor with Girard T and that of 4-phenylpyridine N-oxide and 2-phenylacetophenone vapors with ethanolamine.

Evaluation of Aluminum Ion Vapor Deposition as a Replacement for Cadmium Electroplating at Anniston Army Depot.

DTIC Science & Technology

1992-04-01

for cadmium-coated fasteners can be used for aluminum-plated fasteners if the connections are lubricated (cetyl alcohol or molybdenum disulfide are...pressure to a maximum of 9x10 Torr. Argon gas is then introduced to raise the pressure to about 6x10 " Torr (6 gm). A high -voltage discharge is used to...the chamber to provide even distribution of the aluminum. The aluminum vapor is ionized by transfer of a positive charge from the argon ;ons. Alumi

Effects of E × B drift on electron transport across the magnetic field in a miniature microwave discharge neutralizer

NASA Astrophysics Data System (ADS)

Hiramoto, Kenta; Nakagawa, Yuichi; Koizumi, Hiroyuki; Takao, Yoshinori

2017-06-01

Using a three-dimensional particle-in-cell model, electron transport across a magnetic field has been investigated by obtaining the time-varying electric field and plasma parameters in a miniature microwave discharge neutralizer. The size of the neutralizer is 20 × 20 × 4 mm3. Ring-shaped antenna producing 4.2 GHz microwaves and permanent magnets for xenon plasma discharges are present inside. There are four orifices for electron extraction. The simulation area consists of both the discharge chamber and the vacuum region for the extraction. The numerical results show that radial striped patterns occur where the peak electron density is obtained, and the patterns seem to rotate in the azimuthal direction. This characteristic structure is very similar to recent results obtained in Hall thrusters and is probably due to the electron drift instability. Owing to the plasma structure, the azimuthal electric field is generated, which results in the E × B drift velocity in the axial direction with the radial magnetic field of the permanent magnets. This E × B drift velocity is a key factor in the electron transport across the magnetic field, leading to the electron extraction from the discharge chamber.

The effect of temperature on pulsed positive streamer discharges in air over the range 292 K–1438 K

NASA Astrophysics Data System (ADS)

Ono, Ryo; Ishikawa, Yuta

2018-05-01

The effect of temperature on pulsed positive streamer discharges in air is measured by comparing atmospheric-pressure, high-temperature discharges with low-pressure, room-temperature discharges at the same air densities n and discharge voltages. Both discharges have the same reduced electric field E/n, so the differences between the two discharges only depend on the temperature, which is varied from 292 K to 1438 K. Temperature affects the discharge pulse energy most significantly; at 1438 K, the energy of an atmospheric-pressure discharge pulse is approximately 30 times larger than that of the corresponding 20.5 kPa, room-temperature discharge. Temperature also affects the shapes of the streamers when K, but no significant effect is observed for K. There is also no significant temperature effect on the spatially integrated intensity of N2(C–B) emission. However, temperature strongly affects the ratio of the integrated emission intensity to the discharge energy. No effect of the temperature is observed on the propagation velocity of the primary streamer or on the length of the secondary streamer.

Volatile organic compounds detected in vapor-diffusion samplers placed in sediments along and near the shoreline at Allen Harbor Landfill and Calf Pasture Point, Davisville, Rhode Island, March-April 1998

USGS Publications Warehouse

Lyford, F.P.; Kliever, J.D.; Scott, Clifford

1999-01-01

Volatile organic compounds are present in ground water at the Allen Harbor Landfill and the Calf Pasture Point sites on the former Naval Construction Battalion Center in Davisville, R.I. Vapor-diffusion samplers were used at the two sites during March-April 1998 to identify possible discharge points for contaminants along the shore of Allen Harbor and in two wetland areas near the shore. Results from vapor-diffusion samplers will be used in conjunction with other site information to evaluate proposed ground-water monitoring programs. Volatile organic compounds were detected in 41 of 115 samplers placed along the shoreline at the Allen Harbor Landfill. Trichloroethylene was the principal volatile organic compound detected of eight target compounds. The highest vapor concentration measured exceeded 300,000 parts per billion by volume in an area where TCE was detected in groundwater from nearby monitoring wells. Other chemicals detected in vapor-diffusion samplers included tetrachloroethylene, toluene, and benzene. Concentrations of individual volatile organic compounds were less than 100 parts per billion by volume in most samplers. Volatile organic compounds, principally trichloroethylene, were detected in 7 of 30 samplers placed along the shoreline at Calf Pasture Point; the highest trichloroethylene concentration was 1,900 parts per billion by volume. A trace concentration of tetrachloroethylene was detected in one of the samplers. One of 24 samplers placed in two wetland areas near the shore (suspected discharge areas for ground-water containing volatile organic compounds) detected trichloroethylene at a vapor concentration of 14 parts per billion by volume.

A heated vapor cell unit for dichroic atomic vapor laser lock in atomic rubidium.

PubMed

McCarron, Daniel J; Hughes, Ifan G; Tierney, Patrick; Cornish, Simon L

2007-09-01

The design and performance of a compact heated vapor cell unit for realizing a dichroic atomic vapor laser lock (DAVLL) for the D(2) transitions in atomic rubidium is described. A 5 cm long vapor cell is placed in a double-solenoid arrangement to produce the required magnetic field; the heat from the solenoid is used to increase the vapor pressure and correspondingly the DAVLL signal. We have characterized experimentally the dependence of important features of the DAVLL signal on magnetic field and cell temperature. For the weaker transitions both the amplitude and gradient of the signal are increased by an order of magnitude.

Sub-natural width resonances in Cs vapor confined in micrometric thickness optical cell

NASA Astrophysics Data System (ADS)

Cartaleva, S.; Krasteva, A.; Sargsyan, A.; Sarkisyan, D.; Slavov, D.; Vartanyan, T.

2013-03-01

We present here the behavior of Electromagnetically Induced Transparency (EIT), Velocity Selective Optical Pumping (VSOP) resonances and Velocity Selective Excitation (VSE) resonances observed in Cs vapor confined in а micrometric optical cell (MC) with thickness L = 6λ, λ = 852nm. For comparison of behavior of VSE resonance another conventional optical cell with thickness L=2.5 cm is used. Cells are irradiated in orthogonal to their windows directions by probe beam scanned on the Fg = 4 → Fe= 3, 4, 5 set of transitions and pump beam fixed at the Fg = 3 → Fe = 4 transition, on the D2 line of Cs. The enhanced absorption (fluorescence) narrow VSOP resonance at the closed transition transforms into reduced absorption (fluorescence) one with small increase of atomic concentration or light intensity. A striking difference appears between the VSE resonance broadening in L = 6λ and conventional L = 2.5cm cells.

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

An ionization region model of the reactive Ar/O2 high power impulse magnetron sputtering discharge

NASA Astrophysics Data System (ADS)

Gudmundsson, J. T.; Lundin, D.; Brenning, N.; Raadu, M. A.; Huo, Chunqing; Minea, T. M.

2016-12-01

A new reactive ionization region model (R-IRM) is developed to describe the reactive Ar/O2 high power impulse magnetron sputtering (HiPIMS) discharge with a titanium target. It is then applied to study the temporal behavior of the discharge plasma parameters such as electron density, the neutral and ion composition, the ionization fraction of the sputtered vapor, the oxygen dissociation fraction, and the composition of the discharge current. We study and compare the discharge properties when the discharge is operated in the two well established operating modes, the metal mode and the poisoned mode. Experimentally, it is found that in the metal mode the discharge current waveform displays a typical non-reactive evolution, while in the poisoned mode the discharge current waveform becomes distinctly triangular and the current increases significantly. Using the R-IRM we explore the current increase and find that when the discharge is operated in the metal mode Ar+ and Ti+ -ions contribute most significantly (roughly equal amounts) to the discharge current while in the poisoned mode the Ar+ -ions contribute most significantly to the discharge current and the contribution of O+ -ions, Ti+ -ions, and secondary electron emission is much smaller. Furthermore, we find that recycling of atoms coming from the target, that are subsequently ionized, is required for the current generation in both modes of operation. From the R-IRM results it is found that in the metal mode self-sputter recycling dominates and in the poisoned mode working gas recycling dominates. We also show that working gas recycling can lead to very high discharge currents but never to a runaway. It is concluded that the dominating type of recycling determines the discharge current waveform.

Estimated vapor pressure for WTP process streams

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

Pike, J.; Poirier, M.

Design assumptions during the vacuum refill phase of the Pulsed Jet Mixers (PJMs) in the Hanford Waste Treatment and Immobilization Plant (WTP) equate the vapor pressure of all process streams to that of water when calculating the temperature at which the vacuum refill is reduced or eliminated. WTP design authority asked the authors to assess this assumption by performing calculations on proposed feed slurries to calculate the vapor pressure as a function of temperature. The vapor pressure was estimated for each WTP waste group. The vapor pressure suppression caused by dissolved solids is much greater than the increase caused bymore » organic components such that the vapor pressure for all of the waste group compositions is less than that of pure water. The vapor pressure for each group at 145°F ranges from 81% to 98% of the vapor pressure of water. If desired, the PJM could be operated at higher temperatures for waste groups with high dissolved solids that suppress vapor pressure. The SO4 group with the highest vapor pressure suppression could be operated up to 153°F before reaching the same vapor pressure of water at 145°F. However, most groups would reach equivalent vapor pressure at 147 to 148°F. If any of these waste streams are diluted, the vapor pressure can exceed the vapor pressure of water at mass dilution ratios greater than 10, but the overall effect is less than 0.5%.« less

NPDES (National Pollution Discharge & Elimination System) Minor Dischargers

EPA Pesticide Factsheets

As authorized by the Clean Water Act, the National Pollutant Discharge Elimination System (NPDES) permit program controls water pollution by regulating point sources that discharge pollutants into waters of the United States. The NPDES permit program regulates direct discharges from municipal and industrial wastewater treatment facilities that discharge directly into surface waters. The NPDES permit program is part of the Permit Compliance System (PCS) which issues, records, tracks, and regulates point source discharge facilities. Individual homes that are connected to a municipal system, use a septic system, or do not have a surface discharge do not need an NPDES permit. Facilities in PCS are identified as either major or minor. Within the major/minor classification, facilities are grouped into municipals or non-municipals. In many cases, non-municipals are industrial facilities. This data layer contains Minor dischargers. Major municipal dischargers include all facilities with design flows of greater than one million gallons per day; minor dischargers are less that one million gallons per day. Essentially, a minor discharger does not meet the discharge criteria for a major. Since its introduction in 1972, the NPDES permit program is responsible for significant improvements to our Nation's water quality.

Process for recovering organic vapors from air

DOEpatents

Baker, Richard W.

1985-01-01

A process for recovering and concentrating organic vapor from a feed stream of air having an organic vapor content of no more than 20,000 ppm by volume. A thin semipermeable membrane is provided which has a feed side and a permeate side, a selectivity for organic vapor over air of at least 50, as measured by the ratio of organic vapor permeability to nitrogen permeability, and a permeability of organic vapor of at least 3.times.10.sup.-7 cm.sup.3 (STP) cm/cm.sup.2 sec.cm Hg. The feed stream is passed across the feed side of the thin semipermeable membrane while providing a pressure on the permeate side which is lower than the feed side by creating a partial vacuum on the permeate side so that organic vapor passes preferentially through the membrane to form an organic vapor depleted air stream on the feed side and an organic vapor enriched stream on the permeate side. The organic vapor which has passed through the membrane is compressed and condensed to recover the vapor as a liquid.

Single and multiple streamer DBD micro-discharges for testing inactivation of biologically contaminated surfaces

NASA Astrophysics Data System (ADS)

Prukner, Vaclav; Dolezalova, Eva; Simek, Milan

2014-10-01

Highly reactive environment produced by atmospheric-pressure, non-equilibrium plasmas generated by surface dielectric barrier discharges (SDBDs) may be used for inactivation of biologically contaminated surfaces. We investigated decontamination efficiency of reactive environment produced by single/multiple surface streamer micro-discharge driven by amplitude-modulated AC power in coplanar electrode geometry on biologically contaminated surface by Escherichia coli. The discharges were fed by synthetic air with water vapor admixtures at atmospheric pressure, time of treatment was set from 10 second to 10 minutes, diameters of used SDBD electrodes (single and multiple streamer) and homogeneously contaminated disc samples were equal (25 mm), the distance between the electrode and contaminated surface was 2 mm. Both a conventional cultivation and fluorescent method LIVE/DEAD Bacterial Viability kit were applied to estimate counts of bacteria after the plasma treatment. Inactivation was effective and bacteria partly lost ability to grow and became injured and viable/active but non-cultivable (VBNC/ABNC). Work was supported by the MEYS under Project LD13010, VES13 COST CZ (COST Action MP 1101).

Early weaning from incubator and early discharge of preterm infants: randomized clinical trial.

PubMed

Zecca, Enrico; Corsello, Mirta; Priolo, Francesca; Tiberi, Eloisa; Barone, Giovanni; Romagnoli, Costantino

2010-09-01

The goal was to assess the feasibility of earlier weaning from the incubator for preterm infants. This was a prospective, randomized study with preterm infants with birth weights of <1600 g who were admitted to a neonatal subintensive ward. Findings for 47 infants who were transferred from an incubator to an open crib at >1600 g (early transition group) were compared with those for 47 infants who were transferred from an incubator to an open crib at >1800 g (standard transition [ST] group). The primary outcome of the study was length of stay. Secondary outcomes were the number of infants returned to an incubator, the growth velocity in an open crib and during the first week at home, the proportions of breastfeeding at discharge and during the first week at home, and the hospital readmission rate. The length of stay was significantly shorter in the early transition group than in the standard transition group (23.5 vs 33 days; P=.0002). No infants required transfer back to the incubator. Only 1 infant in the standard transition group was readmitted to the hospital during the first week after discharge. Growth velocities and individual amounts of breastfeeding were similar between the 2 groups. In this study, weaning of moderately preterm infants from incubators to open cribs at 1600 g was safe and resulted in earlier discharge.

Study of discharge cleaning process in JIPP T-2 Torus by residual gas analyzer

NASA Astrophysics Data System (ADS)

Noda, N.; Hirokura, S.; Taniguchi, Y.; Tanahashi, S.

1982-12-01

During discharge cleaning, decay time of water vapor pressure changes when the pressure reaches a certain level. A long decay time observed in the later phase can be interpreted as a result of a slow deoxidization rate of chromium oxide, which may dominate the cleaning process in this phase. Optimization of plasma density for the cleaning is discussed comparing the experimental results on density dependence of water vapor pressure with a result based on a zero dimensional calculation for particle balance. One of the essential points for effective cleaning is the raising of the electron density of the plasma high enough that the dissociation loss rate of H2O is as large as the sticking loss rate. A density as high as 10 to the 11th power/cu cm is required for a clean surface condition where sticking probability is presumed to be around 0.5.

Laboratory Simulation of Electrical Discharge in Surface Lunar Regolith

NASA Astrophysics Data System (ADS)

Shusterman, M.; Izenberg, N.; Wing, B. R.; Liang, S.

2016-12-01

Physical, chemical, and optical characteristics of space-weathered surface materials on airless bodies are produced primarily from bombardment by solar energetic particles and micrometeoroid impacts. On bodies such as the Moon and Mercury, soils in permanently shadowed regions (PSRs) are very cold, have low electrical conductivities, and are subjected to a high flux of incoming energetic particles accelerated by solar events. Theoretical models predict that up to 25% of gardened soils in the lunar polar regions are altered by dielectric breakdown; a potentially significant weathering process that is currently unconfirmed. Although electrical properties of lunar soils have been studied in relation to flight electronics and spacecraft safety, no studies have characterized potential alterations to soils resulting from electrical discharge. To replicate the surface charge field in PSRs, lunar regolith simulant JSC-1A was placed between two parallel plane electrodes under both low and high vacuum environments, 10e-3 torr and 2.5e-6 torr, respectively. Voltage was increased until discharge occurred within the sample. Grains were analyzed using an SVC fiber-fed point spectrometer, Olympus BX51 upright metallurgical microscope, and a Hitachi TM3000 scanning electron microscope with Bruker Quantax-70 X-ray spectrometer. Discharges occurring in samples under low vacuum resulted in surficial melting, silicate vapor deposition, coalescence of metallic iron, and micro-scale changes to surface topography. Samples treated under a high vacuum environment showed similar types of effects, but fewer in number compared to low vacuum samples. The variation in alteration abundances between the two environments implies that discharges may be occurring across surface contaminants, even at high vacuum conditions, inhibiting dielectric breakdown in our laboratory simulations.

Studies on laser-assisted Penning ionization by the optogalvanic effect in Ne/Eu hollow cathode discharge.

PubMed

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

2015-02-01

Laser-assisted Penning ionization (LAPI) is detected in a Ne/Eu hollow cathode (HC) discharge lamp using the pulsed optogalvanic (OG) method. In the Ne/Eu discharge, doubly ionized europium excited energy levels Eu[4f(7)(P(7/2,5/2)6)] lie within the thermal limit (∼kT) from the laser-excited neon's energy level [2p(5)(P3/202)3p or 2p(8) (in Paschen notation)] lying at 149,848  cm(-1). Therefore, Penning ionization (PI) of europium atoms likely to occur into its highly excited ionic states is investigated. To probe the PI of europium, the temporal profiles of its counterpart neon OG signal are studied as a function of discharge current for the transitions (1s(4)→2p(8)) and (1s(2)→2p(2)), corresponding to 650.65 and 659.89 nm wavelengths, respectively. It is observed that PI of europium alters the overall discharge characteristics significantly and, hence, modifies the temporal profile of the OG signals accordingly. The quasi-resonant ionizing energy transfer collisions between laser-excited Ne 2p(8) atoms and electronically excited europium P(9/2)10 atoms are used to explain the LAPI mechanism. Such LAPI studies carried out in HC discharge could be useful for the discharge of a metal-vapor laser with appropriate Penning mixtures.

Measuring snow water equivalent from common-offset GPR records through migration velocity analysis

NASA Astrophysics Data System (ADS)

St. Clair, James; Holbrook, W. Steven

2017-12-01

Many mountainous regions depend on seasonal snowfall for their water resources. Current methods of predicting the availability of water resources rely on long-term relationships between stream discharge and snowpack monitoring at isolated locations, which are less reliable during abnormal snow years. Ground-penetrating radar (GPR) has been shown to be an effective tool for measuring snow water equivalent (SWE) because of the close relationship between snow density and radar velocity. However, the standard methods of measuring radar velocity can be time-consuming. Here we apply a migration focusing method originally developed for extracting velocity information from diffracted energy observed in zero-offset seismic sections to the problem of estimating radar velocities in seasonal snow from common-offset GPR data. Diffractions are isolated by plane-wave-destruction (PWD) filtering and the optimal migration velocity is chosen based on the varimax norm of the migrated image. We then use the radar velocity to estimate snow density, depth, and SWE. The GPR-derived SWE estimates are within 6 % of manual SWE measurements when the GPR antenna is coupled to the snow surface and 3-21 % of the manual measurements when the antenna is mounted on the front of a snowmobile ˜ 0.5 m above the snow surface.

Fresh Versus Marine Submarine Groundwater Discharge: How 222Rn Might Help Distinguish These Two Sources

NASA Astrophysics Data System (ADS)

Smith, C. G.; Cable, J. E.; Martin, J. B.; Roy, M.

2008-05-01

Pore water distributions of 222Rn (t1/2 = 3.83 d), obtained during two sampling trips 9-12 May 2005 and 6-8 May 2006, are used to determine spatial and temporal variations of fluid discharge from a seepage face located along the mainland shoreline of Indian River Lagoon, Florida. Porewater samples were collected from a 30 m transect of multi-level piezometers and analyzed for 222Rn via liquid scintillation counting; the mean of triplicate measurements was used to represent the porewater 222Rn activities. Sediment samples were collected from five vibracores (0, 10, 17.5, 20, and 30 m offshore) and emanation rates of 222Rn (sediment supported) were determined using a standard cryogenic extraction technique. A conceptual 222Rn transport model and subsequent numerical model were developed based on the vertical distribution of dissolved and sediment-supported 222Rn and applicable processes occurring along the seepage face (e.g. advection, diffusion, and nonlocal exchange). The model was solved inversely with the addition of two Monte Carlo (MC) simulations to increase the statistical reliability of three parameters: fresh groundwater seepage velocity (v), irrigation intensity (α0), and irrigation attenuation (α1). The first MC simulation ensures that the Nelder-Mead minimization algorithm converges on a global minimum of the merit function and that the parameters estimates are consistent within this global minimum. The second MC simulation provides 90% confidence intervals on the parameter estimates using the measured 222Rn activity variance. Fresh groundwater seepage velocities obtained from the model decrease linearly with distance from the shoreline; seepage velocities range between 0.6 and 42.2 cm d-1. Based on this linear relationship, the terminus of the fresh groundwater seepage is approximately 25 m offshore and total fresh groundwater discharge for the May-2005 and May-2006 sampling trips are 1.16 and 1.45 m3 d-1 m-1 of shoreline, respectively. We hypothesize

Settling velocity of particulate pollutants from combined sewer wet weather discharges.

PubMed

Gromaire, M C; Kafi-Benyahia, M; Gasperi, J; Saad, M; Moilleron, R; Chebbo, G

2008-01-01

Settling velocities of TSS and of particulate pollutants (COP, PDCO, PTKN, PCu, PPb, PZn, PPAH) measured on a wide range of wet weather flow (WWF) samples collected at different levels of the Parisian combined sewer system are reported. The recorded V30 (0.01 to 0.1 mm s(-1)) and V50 (0.09 to 0.6 mm s(-1)) values exceed by a factor 10 those of dry weather sewage and also exceed the values measured for pavement runoff. These values lie however often below the 0.28 mm s(-1) reference value considered in France for the design of WWF settling facilities. A decrease in settleability is observed between a small upstream catchment and larger scaled downstream catchments. The settling behaviour of particulate pollutants varies depending on the considered parameter and can differ significantly from the TSS behaviour, due to a non homogeneous distribution of micropolluants over the different classes of particles. PZn and PTKN appear far less settleable than TSS, whereas PPAH show higher settleability. IWA Publishing 2008.

BioVapor Model Evaluation

EPA Science Inventory

General background on modeling and specifics of modeling vapor intrusion are given. Three classical model applications are described and related to the problem of petroleum vapor intrusion. These indicate the need for model calibration and uncertainty analysis. Evaluation of Bi...

Stereotactic radiosurgery - discharge

MedlinePlus

Gamma knife - discharge; Cyberknife - discharge; Stereotactic radiotherapy - discharge; Fractionated stereotactic radiotherapy - discharge; Cyclotrons - discharge; Linear accelerator - discharge; Lineacs - discharge; Proton beam radiosurgery - discharge

Using natural distributions of short-lived radium isotopes to quantify groundwater discharge and recharge

USGS Publications Warehouse

Krest, J.M.; Harvey, J.W.

2003-01-01

Radium activity in pore water of wetland sediments often differs from the amount expected from local production, decay, and exchange with solid phases. This disequilibrium results from vertical transport of radium with groundwater that flows between the underlying aquifer and surface water. In situations where groundwater recharge or discharge is significant, the rate of vertical water flow through wetland sediment can be determined from the radium disequilibrium by a combined model of transport, production, decay, and exchange with solid phases. We have developed and tested this technique at three sites in the freshwater portion of the Everglades by quantifying vertical advective velocities in areas with persistent groundwater recharge or discharge and estimating a coefficient of dispersion at a site that is subject to reversals between recharge and discharge. Groundwater velocities (v) were determined to be between 0 and -0.5 cm d-1 for a recharge site and 1.5 ?? 0.4 cm d-1 for a discharge site near Levee 39 in the Everglades. Strong gradients in 223Ra and 224Ra usually occurred at the base of the peat layer, which avoided the problems of other tracers (e.g., chloride) for which greatest sensitivity occurs near the peat surface - a zone readily disturbed by processes unrelated to groundwater flow. This technique should be easily applicable to any wetland system with different production rates of these isotopes in distinct sedimentary layers or surface water. The approach is most straightforward in systems where constant pore-water ionic strength can be assumed, simplifying the modeling of radium exchange.

Magmatic-vapor expansion and the formation of high-sulfidation gold deposits: Chemical controls on alteration and mineralization

USGS Publications Warehouse

Henley, R.W.; Berger, B.R.

2011-01-01

from any external contemporary hydrothermal activity. Subsequent fracturing is localized by the embrittled wallrock to provide high-permeability fracture arrays that constrain vapor expansion with minimization of heat loss. The Sulfide Stage vein sequence is then a consequence of destabilization of metal-vapor species in response to depressurization and decrease in vapor density. The geology, mineralogy, fluid inclusion and stable isotope data and geothermometry for high-sulfidation, bulk-tonnage and lode deposits are quite different from those for epithermal gold-silver deposits such as McLaughlin, California that formed near-surface in groundwater-dominated hydrothermal systems where magmatic fluid has been diluted to less than about 30%. High sulfidation gold deposits are better termed 'Solfataric Gold Deposits' to emphasize this distinction. The magmatic-vapor expansion hypothesis also applies to the phenomenology of acidic geothermal systems in active volcanic systems and equivalent magmatic-vapor discharges on the flanks of submarine volcanoes. ?? 2010.