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Sample records for discharges operating regimes

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

    SciTech Connect

    Prevosto, L. Mancinelli, B.; Chamorro, J. C.; Cejas, E.; Kelly, H.

    2015-02-15

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

  2. Sharp transition between two regimes of operation of dc discharge with two anodes and thermionic emission from cathode

    SciTech Connect

    Mustafaev, A. S.; Grabovskiy, A.; Demidov, V. I.; Kaganovich, I. D.; Koepke, M. E.

    2014-05-15

    In a dc discharge plasma with two anodes and thermionic emission from cathode, the two anodes are used for plasma control. The main anode is placed between the cathode and the other auxiliary anode has a circular opening for passing electron current from the cathode to the second anode. It is experimentally demonstrated that a plasma may exhibit a sudden transition between two quasi-stable conditions as one increases the cathode-electron current collected by the auxiliary anode through an aperture, i.e., hole, in the main anode. In one regime, a bright glowing “ball-shaped double layer” appears on the plasma side having a potential drop of 10–15 eV and concomitant ionization in the neighboring region attached to the opening. The second regime is characterized by a uniform potential profile in plasma and an absence of the ball-shaped double layer. The transition between these regimes is accompanied by a significant change in plasma properties, such as the electron energy distribution function (EEDF). Controlling the EEDF is a valuable capability in technological applications. Increasing the gas pressure leads to the elimination of the first regime for sufficiently high gas pressure, the threshold being a few Torr. The disappearance of a regime transition can be explained by invoking an EEDF transition, from being nonlocal at low pressure to becoming local at high pressure. Local EEDF is determined by local values of electric field. Nonlocal EEDF is determined by electric field values elsewhere, and the electron can travel without energy loss over a path much longer than the discharge dimension.

  3. Determination of the Hall Thruster Operating Regimes

    SciTech Connect

    L. Dorf; V. Semenov; Y. Raitses; N.J. Fisch

    2002-04-09

    A quasi one-dimensional (1-D) steady-state model of the Hall thruster is presented. For the same discharge voltage two operating regimes are possible -- with and without the anode sheath. For given mass flow rate, magnetic field profile and discharge voltage a unique solution can be constructed, assuming that the thruster operates in one of the regimes. However, we show that for a given temperature profile the applied discharge voltage uniquely determines the operating regime: for discharge voltages greater than a certain value, the sheath disappears. That result is obtained over a wide range of incoming neutral velocities, channel lengths and widths, and cathode plane locations. It is also shown that a good correlation between the quasi 1-D model and experimental results can be achieved by selecting an appropriate electron mobility and temperature profile.

  4. Numerical simulation of transitions between back discharge regimes

    NASA Astrophysics Data System (ADS)

    Jánský, Jaroslav; Bessières, Delphine; Paillol, Jean; Lemont, Florent

    2014-11-01

    This paper presents numerical simulations of transitions between back discharge regimes. Back discharge refers to any discharge initiated at or near a dielectric layer covering a passive electrode. In this work, a pinhole in a dielectric layer on a plane anode serves as a model for back discharge activity. We have studied transitions between back discharge regimes by varying the surface charge density on the dielectric layer and the electric field in front of the pinhole. From the variation of these two independent parameters, the back discharge regimes have been depicted as a mode diagram inspired by the experimental study of Masuda and Mizuno. The resulting diagram includes the different discharge regimes that are commonly observed in experiments. The propagation of a positive ionizing wave inside the pinhole toward its edge, and the resulting formation of a plasma zone at its exit constitute the onset stage of back discharge. From this stage, the transitions to volume discharge or surface discharge can occur. The volume discharge regime consists of the propagation of a discharge in space toward the cathode which can be superimposed with the propagation of a discharge above the dielectric layer surface. The diagram reveals the conditions for transitions between back discharge regimes.

  5. Triggering regime of oil-filled trigatron dischargers

    NASA Astrophysics Data System (ADS)

    Kapishnikov, N. K.; Muratov, V. M.

    1986-11-01

    A comparative analysis made in [1, 2] of different types of regulable high-voltage dischargers with liquid insulation showed that trigatrons are currently the most promising for use in high-voltage pulse-operated devices due to their simplicity and reliability. Two basic mechanisms of discharge initiation can be realized in trigatrons — initiation by intensification of the field in the region of the control electrode [2, 3], and triggering by a spark in the ignition gap [4, 5]. The first type of trigatron has been studied sufficiently only for short voltage periods [3, 6, 7], so it is used mainly in switching the pulse-shaping lines of powerful nanosecond pulse generators with “rapid” (0.5 1.5 μsec) charging [8, 9]. Almost no use is now made of the second type of trigatron switch in high-voltage pulse technology due to its unsatisfactory time characteristics. Here we report results of a study of the time characteristics of both types of oil-filled trigatrons operating in a regime whereby they form the leading edge of rectangular voltage pulses with amplitudes up to 800 kV and durations of 1 100 μsec. The goal is to find the optimum conditions for triggering of trigatron dischargers with liquid insulation in the region of microsecond voltage discharges. Experiments were conducted on the unit in [10]. The test discharger was placed in a cylindrical chamber 45 cm in diameter and 27 cm in length. The high-voltage electrode of the discharger was in the form of a cylinder 20 cm in diameter positioned coaxially inside the chamber. The 10-mm-diameter ground electrode was positioned radially in a branch pipe 8 cm long. The control electrode was placed in a 2-cm-diameter hole in the center of the ground electrode. The chamber with the test discharge was filled with transformer oil with a breakdown voltage of about 50 kV. The oil was not replaced or cleaned during the experiment. We did not find that contamination of the oil by discharge products had any effect on the

  6. Statistical instability of barrier microdischarges operating in townsend regime

    SciTech Connect

    Nagorny, V. P.

    2007-01-15

    The dynamics of barrier microdischarges operating in a Townsend regime is studied analytically and via kinetic particle-in-cell/Monte Carlo simulations. It is shown that statistical fluctuations of the number of charged particles in the discharge gap strongly influence the dynamics of natural oscillations of the discharge current and may even lead to a disruption of the discharge. Analysis of the statistical effects based on a simple model is suggested. The role of external sources in stabilizing microdischarges is clarified.

  7. Regime of Improved Confinement and High Beta in Neutral-Beam-Heated Divertor Discharges of the ASDEX Tokamak

    NASA Astrophysics Data System (ADS)

    Wagner, F.; Becker, G.; Behringer, K.; Campbell, D.; Eberhagen, A.; Engelhardt, W.; Fussmann, G.; Gehre, O.; Gernhardt, J.; Gierke, G. V.; Haas, G.; Huang, M.; Karger, F.; Keilhacker, M.; Klüber, O.; Kornherr, M.; Lackner, K.; Lisitano, G.; Lister, G. G.; Mayer, H. M.; Meisel, D.; Müller, E. R.; Murmann, H.; Niedermeyer, H.; Poschenrieder, W.; Rapp, H.; Röhr, H.; Schneider, F.; Siller, G.; Speth, E.; Stäbler, A.; Steuer, K. H.; Venus, G.; Vollmer, O.; Yü, Z.

    1982-11-01

    A new operational regime has been observed in neutral-injection-heated ASDEX divertor discharges. This regime is characterized by high βp values comparable to the aspect ratio A (βp<=0.65A) and by confinement times close to those of Ohmic discharges. The high-βp regime develops at an injection power >=1.9 MW, a mean density n¯e>=3×1013 cm-3, and a q(a) value >=2.6. Beyond these limits or in discharges with material limiter, low βp values and reduced particle and energy confinement times are obtained compared to the Ohmic heating phase.

  8. Exploration of the Townsend regime by discharge light emission in a gas discharge device

    NASA Astrophysics Data System (ADS)

    Hilal Yucel, Kurt

    2014-01-01

    The Townsend discharge mechanism has been explored in a planar microelectronic gas discharge device (MGDD) with different applied voltages U and interelectrode distance d under various pressures in air. The anode and the cathode of the MGDD are formed by a transparent SnO2 covered glass and a GaAs semiconductor, respectively. In the experiments, the discharge is found to be unstable just below the breakdown voltage Ub, whereas the discharge passes through a homogeneous stable Townsend mode beyond the breakdown voltage. The measurements are made by an electrical circuit and a CCD camera by recording the currents and light emission (LE) intensities. The intensity profiles, which are converted from the 3D light emission images along the semiconductor diameter, have been analysed for different system parameters. Different instantaneous conductivity σt regimes are found below and beyond the Townsend region. These regimes govern the current and spatio-temporal LE stabilities in the plasma system. It has been proven that the stable LE region increases up to 550 Torr as a function of pressure for small d. If the active area of the semiconductor becomes larger and the interlectrode distance d becomes smaller, the stable LE region stays nearly constant with pressure.

  9. Steady state plasma operation in RF dominated regimes on EAST

    SciTech Connect

    Zhang, X. J.; Zhao, Y. P.; Gong, X. Z.; Hu, C. D.; Liu, F. K.; Hu, L. Q.; Wan, B. N. Li, J. G.

    2015-12-10

    Significant progress has recently been made on EAST in the 2014 campaign, including the enhanced CW H&CD system over 20MW heating power (LHCD, ICRH and NBI), more than 70 diagnostics, ITER-like W-monoblock on upper divertor, two inner cryo-pumps and RMP coils, enabling EAST to investigate long pulse H mode operation with dominant electron heating and low torque to address the critical issues for ITER. H-mode plasmas were achieved by new H&CD system or 4.6GHz LHCD alone for the first time. Long pulse high performance H mode has been obtained by LHCD alone up to 28s at H{sub 98}∼1.2 or by combing of ICRH and LHCD, no or small ELM was found in RF plasmas, which is essential for steady state operation in the future Tokamak. Plasma operation in low collision regimes were implemented by new 4.6GHz LHCD with core Te∼4.5keV. The non-inductive scenarios with high performance at high bootstrap current fraction have been demonstrated in RF dominated regimes for long pulse operation. Near full non-inductive CD discharges have been achieved. In addition, effective heating and decoupling method under multi-transmitter for ICRF system were developed in this campaign, etc. EAST could be in operation with over 30MW CW heating and current drive power (LHCD ICRH NBI and ECRH), enhanced diagnostic capabilities and full actively-cooled metal wall from 2015. It will therefore allow to access new confinement regimes and to extend these regimes towards to steady state operation.

  10. Stable operating regime for traveling wave devices

    DOEpatents

    Carlsten, Bruce E.

    2000-01-01

    Autophase stability is provided for a traveling wave device (TWD) electron beam for amplifying an RF electromagnetic wave in walls defining a waveguide for said electromagnetic wave. An off-axis electron beam is generated at a selected energy and has an energy noise inherently arising from electron gun. The off-axis electron beam is introduced into the waveguide. The off-axis electron beam is introduced into the waveguide at a second radius. The waveguide structure is designed to obtain a selected detuning of the electron beam. The off-axis electron beam has a velocity and the second radius to place the electron beam at a selected distance from the walls defining the waveguide, wherein changes in a density of the electron beam due to the RF electromagnetic wave are independent of the energy of the electron beam to provide a concomitant stable operating regime relative to the energy noise.

  11. The operating regimes and basic control principles of SNPS Topaz''. [Cs

    SciTech Connect

    Makarov, A.N.; Volberg, M.S.; Grayznov, G.M.; Zhabotinsky, E.E.; Serbin, V.I. )

    1991-01-05

    The basic operating regimes of space nuclear power system (SNPS) Topaz'' are considered. These regimes include: prelaunch preparation and launch into working orbit, SNPS start-up to obtain desired electric power, nominal regime, SNPS shutdown. The main requirements for SNPS at different regimes are given, and the control algorithms providing these requirements are described. The control algorithms were chosen on the basis of theoretical studies and ground power tests of the SNPS prototypes. Topaz'' successful ground and flight tests allow to conclude that for SNPS of this type control algorithm providing required thermal state of cesium vapor supply system and excluding any possibility of discharge processes in current conducting elements is the most expedient at the start-up regime. At the nominal regime required electric power should be provided by maintenance of reactor current and fast-acting voltage regulator utilization. The limitation of the outlet coolant temperature should be foreseen also.

  12. Monitoring and diagnostics systems for nuclear power plant operating regimes

    SciTech Connect

    Abagyan, A.A.; Dmitriev, V.M.; Klebanov, L.A.; Kroshilin, A.E.; Larin, E.P.; Morozov, S.K.

    1988-05-01

    The development of new monitoring and diagnostics systems for Soviet reactors is discussed. An experimental test station is described where industrial operation of new experimental systems can be conducted for purposes of bringing their performance to the level of standard Soviet systems for monitoring reactor operation regimes and equipment resources. The requirements and parameters of the systems are described on a unit-by-unit basis, including the sensor reading monitoring unit, the vibroacoustic monitoring unit, the noise monitoring unit, the accident regime identification unit, and the nonstationary regime monitoring unit. Computer hardware and software requirements are discussed. The results of calculational and experimental research on two complex nonstationary regimes of reactor operation are given. The accident regimes identification unit for the VVER-1000 is analyzed in detail.

  13. Spatio-temporal analysis of discharge regimes based on hydrograph classification techniques in an agricultural catchment

    NASA Astrophysics Data System (ADS)

    Chen, Xiaofei; Bloeschl, Guenter; Blaschke, Alfred Paul; Silasari, Rasmiaditya; Exner-Kittridge, Mike

    2016-04-01

    The stream, discharges and groundwater hydro-graphs is an integration in spatial and temporal variations for small-scale hydrological response. Characterizing discharges response regime in a drainage farmland is essential to irrigation strategies and hydrologic modeling. Especially for agricultural basins, diurnal hydro-graphs from drainage discharges have been investigated to achieve drainage process inferences in varying magnitudes. To explore the variability of discharge responses, we developed an impersonal method to characterize and classify discharge hydrograph based on features of magnitude and time-series. A cluster analysis (hierarchical k-means) and principal components analysis techniques are used for discharge time-series and groundwater level hydro-graphs to analyze their event characteristics, using 8 different discharge and 18 groundwater level hydro-graphs to test. As the variability of rainfall activity, system location, discharge regime and soil moisture pre-event condition in the catchment, three main clusters of discharge hydro-graph are identified from the test. The results show that : (1) the hydro-graphs from these drainage discharges had similar shapes but different magnitudes for individual rainstorm; the similarity is also showed in overland flow discharge and spring system; (2) for each cluster, the similarity of shape insisted, but the rising slope are different due to different antecedent wetness condition and the rain accumulation meanwhile the difference of regression slope can be explained by system location and discharge area; and (3) surface water always has a close proportional relation with soil moisture throughout the year, while only after the soil moisture exceeds a certain threshold does the outflow of tile drainage systems have a direct ratio relationship with soil moisture and a inverse relationship with the groundwater levels. Finally, we discussed the potential application of hydrograph classification in a wider range of

  14. Effective discharge for sediment transport: the sorting role of river flow regimes

    NASA Astrophysics Data System (ADS)

    Basso, Stefano; Sprocati, Riccardo; Frascati, Alessandro; Marani, Marco; Schirmer, Mario; Botter, Gianluca

    2016-04-01

    The effective discharge is a key concept in geomorphology, river engineering and restoration. It is used to design the most stable channel configuration, to estimate sedimentation rate and lifespan of reservoirs and to characterize the hydrologic forcing in models studying long-term evolution of rivers. Previous empirical, theoretical and numerical studies found the effective discharge to be affected by climate, landscape and river morphology, type of transport (dissolved, suspended or bedload), and by streamflow variability. However, the heterogeneity of values observed for the effective discharge challenges a clear understanding of its pivotal drivers, and a consistent framework which explains observations carried out in different catchments and geographic areas is still lacking. This work relates the observed diversity of effective discharge values to the underlying heterogeneity of river flow regimes. The effective ratio (i.e. the ratio between effective discharge and mean streamflow) is derived as a function of the empirical exponent of the sediment rating curve and the streamflow variability, resulting from climatic and landscape drivers. The proposed analytic expression helps to disentangle hydrologic and landscape controls on the effective discharge, and highlights distinct effective ratios of persistent and erratic hydrologic regimes (respectively characterized by low and high flow variability), attributable to intrinsically different streamflow dynamics. The framework captures observed values of effective discharge for suspended sediment transport in a set of catchments of the continental United States, and may allow for first-order estimates of effective discharge in rivers belonging to different climatic regions.

  15. Suppression of Instability of High Pressure DC Microplasma Operating in the Negative Differential Resistance (NDR) Regime

    NASA Astrophysics Data System (ADS)

    Mahamud, Rajib; Farouk, Tanvir I.

    2015-09-01

    Microplasma devices have been the subject of considerable interest and research during the last decade. In a DC system most of the operation regime of the plasma discharges studied fall in the ``abnormal,'' ``normal'' and ``corona'' modes - where a quasi-steady state is achieved. It is well known that even in a DC system the negative differential resistance (NDR) regime can trigger self pulsing discharges. These pulsations are initiated by the parasitic capacitance of the system hence governed by the response time of the power circuit. The circuit response time is required to be larger than the ion transit time to initiate the oscillations. In this present study a suppressor circuit element in the form of an inductor is used to restrain the plasma from switching to a self pulsing mode. It has been identified that the combined response time of the inductor and the plasma discharge (L/Rplasma) has to be larger than the power circuit time constant (RC) to achieve suppression. Inhibition of oscillation has been observed in both experiments and numerical simulations. The obtained voltage-current characteristics show that the inductor element extends the normal glow regime to lower current. Additional parametric simulations are conducted to map out a ``stable'' operation regime. The author would like to thank DARPA (ARO Grant No. W911NF1210007) and University of South Carolina (USC) for the financial support of the work.

  16. Nanosecond Repetitively Pulsed Discharges in Air at Atmospheric Pressure -- Experiment and Theory of Regime Transitions

    NASA Astrophysics Data System (ADS)

    Pai, David; Lacoste, Deanna; Laux, Christophe

    2009-10-01

    In atmospheric pressure air preheated from 300 to 1000 K, the Nanosecond Repetitively Pulsed (NRP) method has been used to generate corona, glow, and spark discharges. Experiments have been performed to determine the parameter space (applied voltage, pulse repetition frequency, ambient gas temperature, and inter-electrode gap distance) of each discharge regime. Notably, there is a minimum gap distance for the existence of the glow regime that increases with decreasing gas temperature. A theory is developed to describe the Corona-to-Glow (C-G) and Glow-to-Spark (G-S) transitions for NRP discharges. The C-G transition is shown to depend on the Avalanche-to-Streamer Transition (AST) as well as the electric field strength in the positive column. The G-S transition is due to the thermal ionization instability. The minimum gap distance for the existence of the glow regime can be understood by considering that the applied voltage of the AST must be lower than that of the thermal ionization instability. This is a previously unknown criterion for generating glow discharges, as it does not correspond to the Paschen minimum or to the Meek-Raether criterion.

  17. Early warning of atmospheric regime transitions using transfer operators

    NASA Astrophysics Data System (ADS)

    Tantet, Alexis; Dijkstra, Henk

    2015-04-01

    The existence of persistent midlatitude atmospheric regimes, such as blocking events, with time scales larger than 5-10 days and indications of preferred transition paths between them motivates the development of early-warning indicators of regime transitions. Here, we use a barotropic model of the northern midlatitudes winter flow to study such meta-stable regimes. We look at estimates of transfer operators acting on densities evolving on a reduced phase space spanned by the first Empirical Orthogonal Functions of the streamfunction and develop an early-warning indicator of zonal to blocked flow transition. The study of the spectra of transfer operators estimated for different lags reveals a multi-level structure in the flow as well as the effect of memory on the reduced dynamics due to past interactions between the resolved and unresolved variables. The slowest motions in the reduced phase space are thereby found to have time scales larger than 8 days and to behave as Markovian for larger lags. These motions are associated with meta-stable regimes and their transitions and can be detected as almost-invariant sets of the transfer operator. The early-warning indicator is based on the action on an initial density of products of the transfer operators estimated for sufficiently long lags, making use of the semi-group property of these operators and shows relatively good Peirce skill score. From the energy budget of the model, we are able to explain the meta-stability of the regimes and the existence of preferred transition paths as the manifestation of barotropic instability. Finally, even though the model is highly simplified, the skill of the early warning indicator is promising, suggesting that the transfer operator approach can be used in parallel to an operational deterministic model for stochastic prediction or to assess forecast uncertainty.

  18. Phase contrast and operation regimes in multifrequency atomic force microscopy

    SciTech Connect

    Santos, Sergio

    2014-04-07

    In amplitude modulation atomic force microscopy the attractive and the repulsive force regimes induce phase shifts above and below 90°, respectively. In the more recent multifrequency approach, however, multiple operation regimes have been reported and the theory should be revisited. Here, a theory of phase contrast in multifrequency atomic force microscopy is developed and discussed in terms of energy transfer between modes, energy dissipation and the kinetic energy and energy transfer associated with externally driven harmonics. The single frequency virial that controls the phase shift might undergo transitions in sign while the average force (modal virial) remains positive (negative)

  19. The Influence of Dam Discharge Regime and Canyon Orientation on Ecosystem Metabolism in the Colorado River

    NASA Astrophysics Data System (ADS)

    Kennedy, T. A.; Tietjen, T.; Wright, S.

    2005-05-01

    Since the closure of Glen Canyon Dam and the beginning of flow regulation of the Colorado River in Grand Canyon in 1963, considerable efforts have been directed toward understanding the aquatic ecology of this altered ecosystem. Understanding what controls resource availability has been a central focus of these efforts because the Colorado River supports populations of sport fish and endangered humpback chub, both of which appear to be strongly resource limited. There is evidence that dam discharge regime and canyon orientation influence algal standing crop due to their effects on water velocity (scour) and solar insolation, respectively. We explored whether these physical factors influenced rates of primary production and ecosystem respiration, two different metrics of resource availability, in the clear tailwater section of the Colorado River by conducting whole system metabolism measurements across a range of discharge regimes and in reaches with different orientation (i.e. N-S vs. E-W). We found that while both discharge regime and canyon orientation influence rates of primary production, seasonal changes in light availability appear to have a far stronger influence on rates of primary production in the Colorado River. Water temperature appeared to be the main driver of ecosystem respiration.

  20. Lava Fountaining Discharge Regime driven by Slug-to-Churn Flow Transition. (Invited)

    NASA Astrophysics Data System (ADS)

    Ripepe, M.; Pioli, L.; Marchetti, E.; Ulivieri, G.

    2013-12-01

    Lava fountaining episodes at Etna volcano appear characterized by the transition between Strombolian and Hawaiian end-member eruptive styles. There is no evidence for this transition in the seismic (i.e. seismic tremor) signal. However, infrasonic records provide unprecedented evidence on this flow transition. Each eruptive episode is characterized by distinctive common trend in the amplitude, waveform and frequency content of the infrasonic wavefield, which evidences the shift from discrete, and transient, strombolian to sustained, and oscillatory, lava fountain dynamics. Large scale experiments on the dynamics of two-phase flow of basaltic magmas show how the transition between different regimes mainly depends on gas volume flow, which in turn controls pressure distribution within the conduit and also magma vesicularity. In particular, while regular large bubble bursting is associated with slug flow regime, large amplitude and low frequency column oscillations are associated with churn flow. In large pipes, transition from slug to churn flow regime is independent on conduit diameter and it is reached at high superficial gas velocity. Lava fountaining episodes at Etna can be thus interpreted as induced by the transition from the slug (discrete strombolian) to churn flow (sustained lava fountain) regimes that is reflecting an increase in the gas discharge rate. Based on laboratory experiments, we calculate that transition between these two end-member explosive regimes at Etna occurs when gas superficial velocity is 76 m/s for near-the-vent stagnant magma conditions.

  1. Hysteresis, regime shifts, and non-stationarity in aquifer recharge-storage-discharge systems

    NASA Astrophysics Data System (ADS)

    Klammler, Harald; Jawitz, James; Annable, Michael; Hatfield, Kirk; Rao, Suresh

    2016-04-01

    Based on physical principles and geological information we develop a parsimonious aquifer model for Silver Springs, one of the largest karst springs in Florida. The model structure is linear and time-invariant with recharge, aquifer head (storage) and spring discharge as dynamic variables at the springshed (landscape) scale. Aquifer recharge is the hydrological driver with trends over a range of time scales from seasonal to multi-decadal. The freshwater-saltwater interaction is considered as a dynamic storage mechanism. Model results and observed time series show that aquifer storage causes significant rate-dependent hysteretic behavior between aquifer recharge and discharge. This leads to variable discharge per unit recharge over time scales up to decades, which may be interpreted as a gradual and cyclic regime shift in the aquifer drainage behavior. Based on field observations, we further amend the aquifer model by assuming vegetation growth in the spring run to be inversely proportional to stream velocity and to hinder stream flow. This simple modification introduces non-linearity into the dynamic system, for which we investigate the occurrence of rate-independent hysteresis and of different possible steady states with respective regime shifts between them. Results may contribute towards explaining observed non-stationary behavior potentially due to hydrological regime shifts (e.g., triggered by gradual, long-term changes in recharge or single extreme events) or long-term hysteresis (e.g., caused by aquifer storage). This improved understanding of the springshed hydrologic response dynamics is fundamental for managing the ecological, economic and social aspects at the landscape scale.

  2. Nanosecond repetitively pulsed discharges in air at atmospheric pressure—the spark regime

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

    Nanosecond repetitively pulsed (NRP) spark discharges have been studied in atmospheric pressure air preheated to 1000 K. Measurements of spark initiation and stability, plasma dynamics, gas temperature and current-voltage characteristics of the spark regime are presented. Using 10 ns pulses applied repetitively at 30 kHz, we find that 2-400 pulses are required to initiate the spark, depending on the applied voltage. Furthermore, about 30-50 pulses are required for the spark discharge to reach steady state, following initiation. Based on space- and time-resolved optical emission spectroscopy, the spark discharge in steady state is found to ignite homogeneously in the discharge gap, without evidence of an initial streamer. Using measured emission from the N2 (C-B) 0-0 band, it is found that the gas temperature rises by several thousand Kelvin in the span of about 30 ns following the application of the high-voltage pulse. Current-voltage measurements show that up to 20-40 A of conduction current is generated, which corresponds to an electron number density of up to 1015 cm-3 towards the end of the high-voltage pulse. The discharge dynamics, gas temperature and electron number density are consistent with a streamer-less spark that develops homogeneously through avalanche ionization in volume. This occurs because the pre-ionization electron number density of about 1011 cm-3 produced by the high frequency train of pulses is above the critical density for streamer-less discharge development, which is shown to be about 108 cm-3.

  3. Operation of Ferroelectric Plasma Sources in a Gas Discharge Mode

    SciTech Connect

    A. Dunaevsky; N.J. Fisch

    2004-03-08

    Ferroelectric plasma sources in vacuum are known as sources of ablative plasma, formed due to surface discharge. In this paper, observations of a gas discharge mode of operation of the ferroelectric plasma sources (FPS) are reported. The gas discharge appears at pressures between approximately 20 and approximately 80 Torr. At pressures of 1-20 Torr, there is a transition from vacuum surface discharge to the gas discharge, when both modes coexist and the surface discharges sustain the gas discharge. At pressures between 20 and 80 Torr, the surface discharges are suppressed, and FPS operate in pure gas discharge mode, with the formation of almost uniform plasma along the entire surface of the ceramics between strips. The density of the expanding plasma is estimated to be about 1013 cm-3 at a distance of 5.5 mm from the surface. The power consumption of the discharge is comparatively low, making it useful for various applications. This paper also presents direct measurements of the yield of secondary electron emission from ferroelectric ceramics, which, at low energies of primary electrons, is high and dependent on the polarization of the ferroelectric material

  4. Star Mode - The improved operating regime of a Fusor

    NASA Astrophysics Data System (ADS)

    Lilley, Matthew; Niasse, Nicolas

    2013-10-01

    It was found in 1997, by G. H. Miley, that Fusors can operate in a regime where the effective transparency of the accelerating grid is greatly enhanced over the value one would traditionally expect from considering the fraction of area taken up by the grid wires. This ``Star Mode'' reduces the heating of the grid wires and so should in principle allow smaller devices to be constructed. At present there is no satisfactory explanation for this Star Mode. In this presentation we revisit some of the basic ideas and offer some new insights into the problem by considering how the discrete symmetry of the system affects the stability of the individual particle orbits.

  5. Operational Regimes and Physics Present in Optoelectronic Tweezers

    PubMed Central

    Valley, Justin K.; Jamshidi, Arash; Ohta, Aaron T.; Hsu, Hsan-Yin; Wu, Ming C.

    2008-01-01

    Optoelectronic tweezers (OET) are a powerful light-based technique for the manipulation of micro- and nanoscopic particles. In addition to an optically patterned dielectrophoresis (DEP) force, other light-induced electrokinetic and thermal effects occur in the OET device. In this paper, we present a comprehensive theoretical and experimental investigation of various fluidic, optical, and electrical effects present during OET operation. These effects include DEP, light-induced ac electroosmosis, electrothermal flow, and buoyancy-driven flow. We present finite-element modeling of these effects to establish the dominant mode for a given set of device parameters and bias conditions. These results are confirmed experimentally and present a comprehensive outline of the operational regimes of the OET device. PMID:19079767

  6. DC negative corona discharge in atmospheric pressure helium: transition from the corona to the ‘normal’ glow regime

    NASA Astrophysics Data System (ADS)

    Hasan, Nusair; Antao, Dion S.; Farouk, Bakhtier

    2014-06-01

    Direct current (dc) negative corona discharges in atmospheric pressure helium are simulated via detailed numerical modeling. Simulations are conducted to characterize the discharges in atmospheric helium for a pin plate electrode configuration. A self-consistent two-dimensional hybrid model is developed to simulate the discharges and the model predictions are validated with experimental measurements. The discharge model considered consists of momentum and energy conservation equations for a multi-component (electrons, ions, excited species and neutrals) gas mixture, conservation equations for each component of the mixture and state relations. A drift-diffusion approximation for the electron and the ion fluxes is used. A model for the external circuit driving the discharge is also considered and solved along with the discharge model. Many of the key features of a negative corona discharge, namely non-linear current-voltage characteristics, spatially flat cathode current density and glow-like discharge in the high current regime are displayed in the predictions. A transition to the ‘normal’ glow discharge from the corona discharge regime is also observed. The transition is identified from the calculated current-voltage characteristic curve and is characterized by the radial growth of the negative glow and the engulfment of the cathode wire.

  7. Governmental oversight of discharges from concentrated animal feeding operations.

    PubMed

    Centner, Terence J

    2006-06-01

    As point sources of pollution in the United States, concentrated animal feeding operations (CAFOs) are subject to the National Pollution Discharge Elimination System permitting system requirements. Changes to federal regulations in 2003 and a 2005 court decision have increased the governmental oversight of CAFOs. Manure application to fields from "large CAFOs" that results in unpermitted discharges can be regulated under the Clean Water Act. The U.S. Environmental Protection Agency's interpretation of agricultural stormwater discharges was approved so that unpermitted discharges may arise if an owner or operator of a CAFO fails to apply manure correctly. Owners and operators do not, however, have a duty to secure governmental permits in the absence of a discharge. Turning to the federal provisions regarding nutrient management plans, a court found that they were deficient. Moreover, the federal government needs to reconsider requirements that would reduce pathogens from entering surface waters. Although these developments should assist in reducing the impairment of U.S. waters, concern still exists. Greater oversight of nutrient management plans and enhanced enforcement efforts offer opportunities to provide greater assurance that CAFO owners and operators will not allow a discharge of pollutants to enter surface waters. PMID:16456627

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

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

  9. Field-emitting Townsend regime of surface dielectric barrier discharges generated in CO2 emerging at high pressure

    NASA Astrophysics Data System (ADS)

    Pai, David; Stauss, Sven; Terashima, Kazuo

    2015-09-01

    Surface dielectric barrier discharges (DBDs) in CO2 from atmospheric pressure up to supercritical conditions (Tc = 304.13 K, pc = 7.4 MPa) generated using 10-kHz ac excitation are studied experimentally. Two discharge regimes are obtained: the standard and field-emitting Townsend regimes. The former resembles typical surface DBDs that have streamer-like characteristics, but the latter has not been reported previously. Here we present an analysis of the electrical and optical diagnostics of the field-emitting Townsend discharge regime using current-voltage and charge-voltage measurements, imaging, optical emission spectroscopy, and spontaneous Raman spectroscopy. Using an electrical model, it is possible to calculate the discharge-induced capacitances of the plasma and the dielectric, as well as the space-averaged values of the surface potential and the potential drop across the discharge. The model also accounts for the space-averaged Laplacian field by including the capacitance due to the fringe electric field from the electrode edge. The electrical characteristics are similar to those of atmospheric-pressure Townsend DBDs, i.e. self-sustained DBDs with minimal space-charge effects. The purely continuum emission spectrum is due to electron-neutral bremsstrahlung, with a corresponding average electron temperature of 2600 K. Raman spectra of CO2 near the critical point demonstrate that the discharge increases the average gas temperature by less than 1 K. This work was supported financially in part by MEXT and JSPS.

  10. Hydrogen discharges operating at atmospheric pressure in a semiconductor gas discharge system

    NASA Astrophysics Data System (ADS)

    Aktas, K.; Acar, S.; Salamov, B. G.

    2011-08-01

    Analyses of physical processes which initiate electrical breakdown and spatial stabilization of current and control it with a photosensitive cathode in a semiconductor gas discharge system (SGDS) are carried out in a wide pressure range up to atmospheric pressure p, interelectrode distance d and diameter D of the electrode areas of the semiconductor cathode. The study compares the breakdown and stability curves of the gas discharge in the planar SGDS where the discharge gap is filled with hydrogen and air in two cases. The impact of the ionizing component of the discharge plasma on the control of the stable operation of the planar SGDS is also investigated at atmospheric pressure. The loss of stability is primarily due to modification of the semiconductor-cathode properties on the interaction with low-energy hydrogen ions and the formation of a space charge of positive ions in the discharge gap which changes the discharge from Townsend to glow type. The experimental results show that the discharge current in H2 is more stable than in air. The breakdown voltages are measured for H2 and air with parallel-plane electrodes, for pressures between 28 and 760 Torr. The effective secondary electron emission (SEE) coefficient is then determined from the breakdown voltage results and compared with the experimental results. The influence of the SEE coefficient is stated in terms of the differences between the experimental breakdown law.

  11. H2OTSTUF: Appropriate Operating Regimes for Magnetohydrodynamic Augmentation

    NASA Technical Reports Server (NTRS)

    Jones, Jonathan E.; Hawk, Clark W.

    1998-01-01

    A trade study of magnetohydrodynamic (MHD) augmented propulsion reveals a unique operating regime at lower thrust levels. Substantial mass savings are realized over conventional chemical, solar, and electrical propulsion concepts when MHD augmentation is used to obtain optimal I(sub sp). However, trip times for the most conservative estimates of power plant specific impulse and accelerator efficiency may be prohibitively long. Quasi-one-dimensional calculations show that a solar or nuclear thermal system augmented by MHD can provide competitive performance while utilizing a diverse range of propellants including water, which is available from the Space Shuttle, the Moon, asteroids, and various moons and planets within our solar system. The use of in-situ propellants will reduce costs of space operations as well as enable human exploration of our Solar System. The following conclusions can be drawn from the results of the mission trade study: (1) There exists a maximum thrust or mass flow rate above which MHD augmentation increases the initial mass in low earth orbit (LEO); (2) Mass saving of over 50% can be realized for unique combination of solar/MHD systems; (3) Trip times for systems utilizing current power supply technology may be prohibitively long. Theoretical predictions of MHD performance for in space propulsion systems show that improved efficiencies can reduce trip times to acceptable levels; (4) Long trip times indicative of low thrust systems can be shortened by an increase in the MHD accelerator efficiency or a decrease in the specific mass of the power supply and power processing unit; and (5) As for all propulsion concepts, missions with larger (Delta)v's benefit more from the increased specific impulse resulting from MHD augmentation. Using a quasi-one-dimensional analysis, the required operating conditions for a MHD accelerator to reach acceptable efficiencies are outlined. This analysis shows that substantial non-equilibrium ionization is

  12. Optimizing Wellfield Operation in a Variable Power Price Regime.

    PubMed

    Bauer-Gottwein, Peter; Schneider, Raphael; Davidsen, Claus

    2016-01-01

    Wellfield management is a multiobjective optimization problem. One important objective has been energy efficiency in terms of minimizing the energy footprint (EFP) of delivered water (MWh/m(3) ). However, power systems in most countries are moving in the direction of deregulated markets and price variability is increasing in many markets because of increased penetration of intermittent renewable power sources. In this context the relevant management objective becomes minimizing the cost of electric energy used for pumping and distribution of groundwater from wells rather than minimizing energy use itself. We estimated EFP of pumped water as a function of wellfield pumping rate (EFP-Q relationship) for a wellfield in Denmark using a coupled well and pipe network model. This EFP-Q relationship was subsequently used in a Stochastic Dynamic Programming (SDP) framework to minimize total cost of operating the combined wellfield-storage-demand system over the course of a 2-year planning period based on a time series of observed price on the Danish power market and a deterministic, time-varying hourly water demand. In the SDP setup, hourly pumping rates are the decision variables. Constraints include storage capacity and hourly water demand fulfilment. The SDP was solved for a baseline situation and for five scenario runs representing different EFP-Q relationships and different maximum wellfield pumping rates. Savings were quantified as differences in total cost between the scenario and a constant-rate pumping benchmark. Minor savings up to 10% were found in the baseline scenario, while the scenario with constant EFP and unlimited pumping rate resulted in savings up to 40%. Key factors determining potential cost savings obtained by flexible wellfield operation under a variable power price regime are the shape of the EFP-Q relationship, the maximum feasible pumping rate and the capacity of available storage facilities. PMID:25964991

  13. Compact waveguide grating couplers operating in the strong coupling regime

    NASA Astrophysics Data System (ADS)

    Wang, Bin

    2005-07-01

    Since both photonic crystal and high index contrast waveguide photonic devices allow for tighter bend radii and thus reduced die size, they are being actively investigated for use in dense planar lightwave circuits (PLCs). To fully realize highly integrated PLCs, an efficient optical connection interface between single mode fibers or fiber arrays and high-index-contrast waveguides is required. The core size of single-mode fiber is typically 4--9mum while the core size of high-index-contrast waveguides is usually less than 1 to 2mum. Due to the mode size mismatch between the fiber and the waveguide, coupling light into small waveguides is challenging. This results in prohibitive insertion loss and extreme difficulty in fiber alignment for simple pigtail coupling, in which the end of a fiber is aligned and placed next to the end face of a waveguide. In addition, with input and output coupling taking place only along the edge of a chip at the plane of the waveguide device layer, this edge coupling arrangement severely limits the number of optical I/Os in dense PLCs. Moreover, fiber alignment has to be done after the wafer is diced into separate chips, and the end facet of the waveguide needs to be cut and polished. As a result, alignment and packaging accounts for the main manufacturing cost of optical components. In order to fully realize the potential of highly integrated PLCs, a new coupling approach needs to be developed, especially one that permits input and output to a 2-D array of fibers. The goal of this dissertation is to develop a high efficiency coupling method based on grating couplers operating in the strong coupling regime for fibers oriented normal to the waveguide plane without any intermediate optics between the fibers and waveguides. Development of this capability allows for relaxed fiber alignment requirements and wafer-scale alignment and testing. In this dissertation, three types of grating couplers that operate in the strong coupling regime are

  14. Diffuse barrier discharges in nitrogen with small admixtures of oxygen: discharge mechanism and transition to the filamentary regime

    NASA Astrophysics Data System (ADS)

    Brandenburg, R.; Maiorov, V. A.; Golubovskii, Yu B.; Wagner, H.-E.; Behnke, J.; Behnke, J. F.

    2005-07-01

    Diffuse barrier discharges (BDs) are characterized by the periodicity of their discharge current and by the uniform coverage of the entire electrode surface by the plasma. Up to now the discharge development, their appearance and dynamics cannot be adequately explained by elementary processes. Different processes are discussed in the literature controversially, in particular the importance of volume and surface processes on the pre-ionization (Penning-ionization, secondary (γ-) processes, role of surface charges). Diffuse BDs in nitrogen with small admixtures of oxygen are investigated by plasma diagnostics (current/voltage-oscillography, optical emission spectroscopy) and numerical modelling. Special attention is paid to the transition to the usual filamentary mode, characterized by the presence of micro-discharges and caused by the admixture of oxygen in the range of 0-1200 ppm (parts-per-million). This transition starts at low values of O2 (about 450 ppm) and is introduced by an oscillative multi-peak mode. At higher admixtures (about 1000 ppm) the micro-discharges are generated. According to the results of numerical modelling, secondary electron emission by N2(A 3Σu) metastable states plays a major role in discharge maintenance. Due to the much more effective quenching of these states by O2 and NO than by N2 the subsequent delivery of electrons will be decreased when the oxygen amount is increased.

  15. Regime-shifting streamflow processes: Implications for water supply reservoir operations

    NASA Astrophysics Data System (ADS)

    Turner, S. W. D.; Galelli, S.

    2016-05-01

    This paper examines the extent to which regime-like behavior in streamflow time series impacts reservoir operating policy performance. We begin by incorporating a regime state variable into a well-established stochastic dynamic programming model. We then simulate and compare optimized release policies—with and without the regime state variable—to understand how regime shifts affect operating performance in terms of meeting water delivery targets. Our optimization approach uses a Hidden Markov Model to partition the streamflow time series into a small number of separate regime states. The streamflow persistence structures associated with each state define separate month-to-month streamflow transition probability matrices for computing penalty cost expectations within the optimization procedure. The algorithm generates a four-dimensional array of release decisions conditioned on the within-year time period, reservoir storage state, inflow class, and underlying regime state. Our computational experiment is executed on 99 distinct, hypothetical water supply reservoirs fashioned from the Australian Bureau of Meteorology's Hydrologic Reference Stations. Results show that regime-like behavior is a major cause of suboptimal operations in water supply reservoirs; conventional techniques for optimal policy design may misguide the operator, particularly in regions susceptible to multiyear drought. Stationary streamflow models that allow for regime-like behavior can be incorporated into traditional stochastic optimization models to enhance the flexibility of operations.

  16. ATC contingency operations in the en-route flight regime

    NASA Technical Reports Server (NTRS)

    Lyman, E. G.

    1981-01-01

    Air traffic control (ATC) operations were examined to learn what factors of controller performance should be given consideration in the design and development of future automation systems enhancing ATC. Contingencies were of two types: those constraining airspace usage or traffic flow (i.e., weather); and those related to system and equipment usage (i.e., radar/radio status). Examination of controller response to contingencies and workload pressures showed differing effects on controller allocations of effort among the three primary function of planning, monitoring, and informaton transfer. Automation advancements oriented towards aiding the controller in performing monitoring tasks may offer the most substantial safety benefit.

  17. Experimental analysis on the effects of DC arc discharges at various flow regimes

    SciTech Connect

    Bianchi, G.; Saracoglu, B. H. Regert, T.; Paniagua, G.

    2015-03-15

    This paper addresses the control of the boundary layer on a compression ramp by means of DC electrical arc discharges. The development and realization of the control system are first described and then assessed in the wind tunnel. The objective of the research was to control the supersonic flow using the minimum amount of energy. The array of electrodes was located at the base of a ramp, where a low momentum flow develops. The electrical discharge was generated by a custom designed electronic facility based on high-voltage ignition coils. The slanted tungsten electrodes were insulated by mounting them in a ceramic support. The discharge evolution was studied through high-speed flow visualizations, while electrical measurements at the high-voltage section of the circuitry allowed to estimate the energy release. The development of a high-speed short exposure Schlieren imaging technique, based on a very short duration laser pulse illumination and a double shot CCD camera, allowed to observe the macroscopic effects associated with the arc establishment between the electrodes (glow, sound wave and heat release). Due to the long residence time, the thermal perturbation spread along the streamwise direction. Cross correlation of Schlieren images with short time separation revealed that in supersonic conditions, the discharges led to an overall acceleration of the flow field underneath the oblique shock wave.

  18. Experimental analysis on the effects of DC arc discharges at various flow regimes

    NASA Astrophysics Data System (ADS)

    Bianchi, G.; Saracoglu, B. H.; Paniagua, G.; Regert, T.

    2015-03-01

    This paper addresses the control of the boundary layer on a compression ramp by means of DC electrical arc discharges. The development and realization of the control system are first described and then assessed in the wind tunnel. The objective of the research was to control the supersonic flow using the minimum amount of energy. The array of electrodes was located at the base of a ramp, where a low momentum flow develops. The electrical discharge was generated by a custom designed electronic facility based on high-voltage ignition coils. The slanted tungsten electrodes were insulated by mounting them in a ceramic support. The discharge evolution was studied through high-speed flow visualizations, while electrical measurements at the high-voltage section of the circuitry allowed to estimate the energy release. The development of a high-speed short exposure Schlieren imaging technique, based on a very short duration laser pulse illumination and a double shot CCD camera, allowed to observe the macroscopic effects associated with the arc establishment between the electrodes (glow, sound wave and heat release). Due to the long residence time, the thermal perturbation spread along the streamwise direction. Cross correlation of Schlieren images with short time separation revealed that in supersonic conditions, the discharges led to an overall acceleration of the flow field underneath the oblique shock wave.

  19. Operational Regimes of the National Spherical Torus Experiment

    SciTech Connect

    D. Mueller; M.G. Bell; R.E. Bell; M. Bitter; T. Bigelow; P. Bonoli; M. Carter; J. Ferron; E. Fredrickson; D. Gates; L. Grisham; J.C. Hosea; D. Johnson; R. Kaita; S.M. Kaye; H. Kugel; B.P. LeBlanc; R. Maingi; R. Majeski; R. Maqueda; J. Menard; M. Ono; F. Paoletti; S. Paul; C.K. Phillips; R. Pinsker; R. Raman; S.A. Sabbagh; C.H. Skinner; V.A. Soukhanovskii; D. Stutman; D. Swain; Y. Takase; J. Wilgen; J.R. Wilson; G.A. Wurden; S. Zweben

    2002-06-03

    The National Spherical Torus Experiment (NSTX) is a proof-of-principle experiment designed to study the physics of Spherical Tori (ST), i.e., low-aspect-ratio toroidal plasmas. Important issues for ST research are whether the high-eta stability and reduced transport theoretically predicted for this configuration can be realized experimentally. In NSTX, the commissioning of a digital real-time plasma control system, the provision of flexible heating systems, and the application of wall conditioning techniques were instrumental in achieving routine operation with good confinement. NSTX has produced plasmas with R/a {approx} 0.85 m/0.68 m, A {approx} 1.25, Ip * 1.1 MA, BT = 0.3-0.45 T, k * 2.2, d * 0.5, with auxiliary heating by up to 4 MW of High Harmonic Fast Waves, and 5 MW of 80 keV D0 Neutral Beam Injection (NBI). The energy confinement time in plasmas heated by NBI has exceeded 100 ms and a toroidal beta (bT = 2m0

    /BT02, where BT0 is the central vacuum toroidal magnetic field) up to 22% has be en achieved. HHFW power of 2.3 MW has increased the electron temperature from an initial 0.4 keV to 0.9 keV both with and without producing a significant density rise in the plasma. The early application of both NBI and HHFW heating has slowed the penetration of the inductively produced plasma current, modifying the current profile and, thereby, the observed MHD stability.

  20. Two-wave regime of operation of the high-harmonic gyrotron

    SciTech Connect

    Savilov, A. V.; Denisov, G. G.; Kalynov, Yu. K.; Osharin, I. V.

    2015-04-15

    The use of the two-wave co-generation is proposed as a way to decrease the effective Q-factor of the operating near-cutoff wave of the gyrotron. In this two-wave regime, the operating wave represents a “hot” wave mode formed by two partial “cold” modes (near-cutoff and far-from-cutoff ones) coupled on the electron beam. It is shown that the use of this regime can provide a significant decrease of the Ohmic losses in low-relativistic high-harmonic gyrotrons operating in the THz frequency range.

  1. Development of a Discharge Channel upon Electric Explosion of a Wire in Interrupted- and Uninterrupted-Current Regimes

    SciTech Connect

    Romanova, Vera; Tkachenko, Svetlana; Mingaleev, Albert; Agafonov, Alexey; Ter-Oganesyan, Alexey; Shelkovenko, Tatiana; Pikuz, Sergey

    2009-01-21

    Experimental results on the electrical explosion of thin W, Cu and Ni wires with a current density of {approx}10{sup 12} A/m{sup 2}, a current rise rate (dI/dt){approx}40 A/ns and a current pulse with amplitude 9 kA are presented. The structures of the discharge channels developed in single wire explosions in air and vacuum using laser shadow and schlieren imaging have been studied under the condition that the current in the circuit was interrupted. A difference in the shock wave propagation in air and the expansion of the exploded wire dense core in interrupted- and uninterrupted-current regimes has been observed. Analysis of the optical images has been performed in a shunting breakdown scenario.

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

    SciTech Connect

    Wang Qi; Sun Jizhong; Wang Dezhen

    2011-10-15

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

  3. Discharge regime of non-ambipolarity with a self-induced steady-state magnetic field in plasma sources with localized radio-frequency power deposition

    SciTech Connect

    Shivarova, A. Lishev, St.; Todorov, D.; Paunska, Ts.

    2015-10-15

    Involving the idea for the Biermann effect known from space physics as well as recent discussions on non-ambipolarity of the electron and ion fluxes in low-pressure discharges, the study builds the discharge pattern in a source with localized RF power deposition outside the region of high electron density. A vortex dc current flowing in an RF discharge and a steady-state magnetic field induced by this current govern the discharge behavior. Owing to a shift in the positions of the electron-density and plasma-potential maxima, the dc current is driven with the purpose of keeping the conservativity of the dc field in the discharge. The results present the spatial structure of a discharge in a regime of non-ambipolarity of the electron and ion fluxes, including its modifications by the magnetic field.

  4. The quiescent H-mode regime for high performance edge localized mode-stable operation in future burning plasmasa)

    NASA Astrophysics Data System (ADS)

    Garofalo, A. M.; Burrell, K. H.; Eldon, D.; Grierson, B. A.; Hanson, J. M.; Holland, C.; Huijsmans, G. T. A.; Liu, F.; Loarte, A.; Meneghini, O.; Osborne, T. H.; Paz-Soldan, C.; Smith, S. P.; Snyder, P. B.; Solomon, W. M.; Turnbull, A. D.; Zeng, L.

    2015-05-01

    For the first time, DIII-D experiments have achieved stationary quiescent H-mode (QH-mode) operation for many energy confinement times at simultaneous ITER-relevant values of beta, confinement, and safety factor, in an ITER-like shape. QH-mode provides excellent energy confinement, even at very low plasma rotation, while operating without edge localized modes (ELMs) and with strong impurity transport via the benign edge harmonic oscillation (EHO). By tailoring the plasma shape to improve the edge stability, the QH-mode operating space has also been extended to densities exceeding 80% of the Greenwald limit, overcoming the long-standing low-density limit of QH-mode operation. In the theory, the density range over which the plasma encounters the kink-peeling boundary widens as the plasma cross-section shaping is increased, thus increasing the QH-mode density threshold. The DIII-D results are in excellent agreement with these predictions, and nonlinear magnetohydrodynamic analysis of reconstructed QH-mode equilibria shows unstable low n kink-peeling modes growing to a saturated level, consistent with the theoretical picture of the EHO. Furthermore, high density operation in the QH-mode regime has opened a path to a new, previously predicted region of parameter space, named "Super H-mode" because it is characterized by very high pedestals that can be more than a factor of two above the peeling-ballooning stability limit for similar ELMing H-mode discharges at the same density.

  5. Operation of the ISL transonic shock tube in a high subsonic flow regime

    NASA Astrophysics Data System (ADS)

    Seiler, F.; Havermann, M.; Boller, F.; Mangold, P.; Takayama, K.

    The transonic flow regime plays an important role in experimental aerodynamic research. Modern civil aircraft fly up to a Mach number of M ≈ 0.9 in the high subsonic speed regime, as, for example, the Boeing or Airbus passenger aircraft. Nearly sonic Mach numbers are foreseen for innovative airplane concepts like the sonic cruiser by Boeing. In the military domain, guided missiles like the cruise missile also fly in the high subsonic flow regime. For testing purposes, transonic wind tunnels are mainly used for sub- as well as supersonic design applications. These wind tunnels have normally very large dimensions, which makes their operation quite expensive. If only small scale tests are required, a cheap working facility turns out to be more beneficial. For this purpose, a conventional shock tube operated at transonic flow conditions has been put into operation at the ISL. In the transonic flow regime, however, the reduction of the tube cross section by the model can produce severe distortions followed by a choking of the shock tube flow in the test section. Extensive experimental investigations were performed to determine the subsonic choking Mach number as a function of the model size. These results are compared with theoretical estimations and, more in detail, with CFD calculations.

  6. Operation regimes and slower-is-faster effect in the control of traffic intersections

    NASA Astrophysics Data System (ADS)

    Helbing, D.; Mazloumian, A.

    2009-07-01

    The efficiency of traffic flows in urban areas is known to crucially depend on signal operation. Here, elements of signal control are discussed, based on the minimization of overall travel times or vehicle queues. Interestingly, we find different operation regimes, some of which involve a “slower-is-faster effect”, where a delayed switching reduces the average travel times. These operation regimes characterize different ways of organizing traffic flows in urban road networks. Besides the optimize-one-phase approach, we discuss the procedure and advantages of optimizing multiple phases as well. To improve the service of vehicle platoons and support the self-organization of “green waves”, it is proposed to consider the price of stopping newly arriving vehicles.

  7. Systematic investigation of the barrier discharge operation in helium, nitrogen, and mixtures: discharge development, formation and decay of surface charges

    NASA Astrophysics Data System (ADS)

    Tschiersch, R.; Bogaczyk, M.; Wagner, H.-E.

    2014-09-01

    As a logical extension to previous investigations of the barrier discharge (BD) in helium and nitrogen, the present work reports on the operation in any mixtures of both pure gases. Using a well-established plane-parallel discharge cell configuration allows to study the influence of the He/N2 mixing ratio on the formation of different discharge modes. Their characterization was made by measuring the discharge emission development together with the formation and decay of surface charges on a bismuth silicon oxide (Bi12SiO20, BSO) crystal. This was realized by the simultaneous application of the spatio-temporally resolved optical emission spectroscopy, and the electro-optic Pockels effect in combination with a CCD high speed camera. The existence diagram for diffuse and filamentary BDs was determined by varying the amplitude and shape of the applied voltage. Over the entire range of the He/N2 ratio, the diffuse mode can be operated at moderate voltage amplitudes whereas filamentation occurs at significant overvoltage and is favoured by a high voltage slew rate. Irrespective of the discharge mode, the overall charge transfer during a discharge breakdown is found to be in excellent agreement with the amount of accumulated surface charges. An exponential decay of the surface charge deposited on the BSO crystal is induced by LED illumination beyond a typical discharge cycle. During the decay process, a broadening of the radial profiles of positive as well as negative surface charge spots originating from previous microdischarges is observed. The investigations contribute to a better understanding of the charge accumulation at a dielectric.

  8. Analysis of the operating regimes of microsecond-conduction-time plasma opening switches

    NASA Astrophysics Data System (ADS)

    Cassany, B.; Grua, P.

    1995-07-01

    A theoretical model for the microsecond-conduction-time plasma opening switch (POS) based on magnetohydrodynamics is presented. The operating processes are associated with the magnetic field transport in the switch. The concept of the freezing-in of magnetic field in fluids is used to analyse the dynamics of this field in the plasma. One-dimensional and two-dimensional numerical simulations lead to the identification of two operating regimes, related to the Hall and the snowplow effects. The transition between these two regimes is determined by the plasma density. Scaling relations are developed from this model. In particular the electrical charge Q, conducted by the POS during the conduction time, provides a useful tool for comparisons between theory and experiments; it is shown to be the essential parameter for the switch design.

  9. High energy bursts from a solid state laser operated in the heat capacity limited regime

    DOEpatents

    Albrecht, Georg; George, E. Victor; Krupke, William F.; Sooy, Walter; Sutton, Steven B.

    1996-01-01

    High energy bursts are produced from a solid state laser operated in a heat capacity limited regime. Instead of cooling the laser, the active medium is thermally well isolated. As a result, the active medium will heat up until it reaches some maximum acceptable temperature. The waste heat is stored in the active medium itself. Therefore, the amount of energy the laser can put out during operation is proportional to its mass, the heat capacity of the active medium, and the temperature difference over which it is being operated. The high energy burst capacity of a heat capacity operated solid state laser, together with the absence of a heavy, power consuming steady state cooling system for the active medium, will make a variety of applications possible. Alternately, cooling takes place during a separate sequence when the laser is not operating. Industrial applications include new material working processes.

  10. High energy bursts from a solid state laser operated in the heat capacity limited regime

    DOEpatents

    Albrecht, G.; George, E.V.; Krupke, W.F.; Sooy, W.; Sutton, S.B.

    1996-06-11

    High energy bursts are produced from a solid state laser operated in a heat capacity limited regime. Instead of cooling the laser, the active medium is thermally well isolated. As a result, the active medium will heat up until it reaches some maximum acceptable temperature. The waste heat is stored in the active medium itself. Therefore, the amount of energy the laser can put out during operation is proportional to its mass, the heat capacity of the active medium, and the temperature difference over which it is being operated. The high energy burst capacity of a heat capacity operated solid state laser, together with the absence of a heavy, power consuming steady state cooling system for the active medium, will make a variety of applications possible. Alternately, cooling takes place during a separate sequence when the laser is not operating. Industrial applications include new material working processes. 5 figs.

  11. 33 CFR 151.69 - Operating requirements: Discharge of garbage outside special areas.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., GARBAGE, MUNICIPAL OR COMMERCIAL WASTE, AND BALLAST WATER Implementation of MARPOL 73/78 and the Protocol... Pollution and Sewage § 151.69 Operating requirements: Discharge of garbage outside special areas. (a) Except...; and (3) 100 nautical miles and the maximum water depth possible for animal carcasses. Discharge...

  12. 33 CFR 151.71 - Operating requirements: Discharge of garbage within special areas.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., GARBAGE, MUNICIPAL OR COMMERCIAL WASTE, AND BALLAST WATER Implementation of MARPOL 73/78 and the Protocol... Pollution and Sewage § 151.71 Operating requirements: Discharge of garbage within special areas. (a) When a... garbage into the water, except as allowed in this section. (b) Food wastes shall only be discharged...

  13. 33 CFR 151.71 - Operating requirements: Discharge of garbage within special areas.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., GARBAGE, MUNICIPAL OR COMMERCIAL WASTE, AND BALLAST WATER Implementation of MARPOL 73/78 and the Protocol... Pollution and Sewage § 151.71 Operating requirements: Discharge of garbage within special areas. (a) When a... garbage into the water, except as allowed in this section. (b) Food wastes shall only be discharged...

  14. 33 CFR 151.69 - Operating requirements: Discharge of garbage outside special areas.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., GARBAGE, MUNICIPAL OR COMMERCIAL WASTE, AND BALLAST WATER Implementation of MARPOL 73/78 and the Protocol... Pollution and Sewage § 151.69 Operating requirements: Discharge of garbage outside special areas. (a) Except...; and (3) 100 nautical miles and the maximum water depth possible for animal carcasses. Discharge...

  15. 33 CFR 151.79 - Operating requirements: Discharge of sewage within Antarctica.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... of sewage within Antarctica. 151.79 Section 151.79 Navigation and Navigable Waters COAST GUARD... Pollution and Sewage § 151.79 Operating requirements: Discharge of sewage within Antarctica. (a) A vessel certified to carry more than 10 persons must not discharge untreated sewage into the sea within 12...

  16. 33 CFR 151.79 - Operating requirements: Discharge of sewage within Antarctica.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... of sewage within Antarctica. 151.79 Section 151.79 Navigation and Navigable Waters COAST GUARD... Pollution and Sewage § 151.79 Operating requirements: Discharge of sewage within Antarctica. (a) A vessel certified to carry more than 10 persons must not discharge untreated sewage into the sea within 12...

  17. 33 CFR 151.79 - Operating requirements: Discharge of sewage within Antarctica.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... of sewage within Antarctica. 151.79 Section 151.79 Navigation and Navigable Waters COAST GUARD... Pollution and Sewage § 151.79 Operating requirements: Discharge of sewage within Antarctica. (a) A vessel certified to carry more than 10 persons must not discharge untreated sewage into the sea within 12...

  18. 33 CFR 151.79 - Operating requirements: Discharge of sewage within Antarctica.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... of sewage within Antarctica. 151.79 Section 151.79 Navigation and Navigable Waters COAST GUARD... Pollution and Sewage § 151.79 Operating requirements: Discharge of sewage within Antarctica. (a) A vessel certified to carry more than 10 persons must not discharge untreated sewage into the sea within 12...

  19. 33 CFR 151.79 - Operating requirements: Discharge of sewage within Antarctica.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... of sewage within Antarctica. 151.79 Section 151.79 Navigation and Navigable Waters COAST GUARD... Pollution and Sewage § 151.79 Operating requirements: Discharge of sewage within Antarctica. (a) A vessel certified to carry more than 10 persons must not discharge untreated sewage into the sea within 12...

  20. 33 CFR 151.67 - Operating requirements: Discharge of plastic prohibited.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... of plastic prohibited. 151.67 Section 151.67 Navigation and Navigable Waters COAST GUARD, DEPARTMENT... Sewage § 151.67 Operating requirements: Discharge of plastic prohibited. No person on board any ship may discharge into the sea, or into the navigable waters of the United States, plastic or garbage mixed...

  1. 33 CFR 151.67 - Operating requirements: Discharge of plastic prohibited.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... of plastic prohibited. 151.67 Section 151.67 Navigation and Navigable Waters COAST GUARD, DEPARTMENT... Sewage § 151.67 Operating requirements: Discharge of plastic prohibited. No person on board any ship may discharge into the sea, or into the navigable waters of the United States, plastic or garbage mixed...

  2. 33 CFR 151.67 - Operating requirements: Discharge of plastic prohibited.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... of plastic prohibited. 151.67 Section 151.67 Navigation and Navigable Waters COAST GUARD, DEPARTMENT... Sewage § 151.67 Operating requirements: Discharge of plastic prohibited. No person on board any ship may discharge into the sea, or into the navigable waters of the United States, plastic or garbage mixed...

  3. 33 CFR 151.67 - Operating requirements: Discharge of plastic prohibited.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... of plastic prohibited. 151.67 Section 151.67 Navigation and Navigable Waters COAST GUARD, DEPARTMENT... Sewage § 151.67 Operating requirements: Discharge of plastic prohibited. No person on board any ship may discharge into the sea, or into the navigable waters of the United States, plastic or garbage mixed...

  4. 33 CFR 151.67 - Operating requirements: Discharge of plastic prohibited.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... of plastic prohibited. 151.67 Section 151.67 Navigation and Navigable Waters COAST GUARD, DEPARTMENT... Sewage § 151.67 Operating requirements: Discharge of plastic prohibited. No person on board any ship may discharge into the sea, or into the navigable waters of the United States, plastic or garbage mixed...

  5. Control of Oxygen Delamination in Solid Oxide Electrolyzer Cells via Modifying Operational Regime

    SciTech Connect

    Sergey N. Rashkeev; Michael V. Glazoff

    2011-10-01

    Possible modifications of operational regimes for solid oxide fuel cell (SOEC) devices for hydrogen production are discussed. It is shown that applying alternating current (AC) voltage pulses at a certain frequency range to SOECs could reduce oxygen delamination degradation in these devices and significantly increase their lifetime. This operational scheme provides wide possibilities to increase longevity of SOEC devices required for their use in commercial hydrogen production processes, without any significant modification of used materials and/or cell design. Developed simulation method possesses a broad generality and be employed in a number of other industrial processes.

  6. 33 CFR 151.73 - Operating requirements: Discharge of garbage from fixed or floating platforms.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... SUBSTANCES, GARBAGE, MUNICIPAL OR COMMERCIAL WASTE, AND BALLAST WATER Implementation of MARPOL 73/78 and the... Pollution and Sewage § 151.73 Operating requirements: Discharge of garbage from fixed or floating...

  7. 33 CFR 151.73 - Operating requirements: Discharge of garbage from fixed or floating platforms.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... SUBSTANCES, GARBAGE, MUNICIPAL OR COMMERCIAL WASTE, AND BALLAST WATER Implementation of MARPOL 73/78 and the... Pollution and Sewage § 151.73 Operating requirements: Discharge of garbage from fixed or floating...

  8. 33 CFR 151.73 - Operating requirements: Discharge of garbage from fixed or floating platforms.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... SUBSTANCES, GARBAGE, MUNICIPAL OR COMMERCIAL WASTE, AND BALLAST WATER Implementation of MARPOL 73/78 and the... Pollution and Sewage § 151.73 Operating requirements: Discharge of garbage from fixed or floating...

  9. A New Look at the GEO and Near-GEO Regimes: Operations, Disposals, and Debris

    NASA Technical Reports Server (NTRS)

    Johnson, Nicholas

    2011-01-01

    Since 1963 more than 900 spacecraft and more than 200 launch vehicle upper stages have been inserted into the vicinity of the geosynchronous regime. Equally important, more than 300 spacecraft have been maneuvered into disposal orbits at mission termination to alleviate unnecessary congestion in the finite GEO region. However, the number of GEO satellites continues to grow, and evidence exists of a substantial small debris population. In addition, the operational modes of an increasing number of GEO spacecraft differ from those of their predecessors of several decades ago, including more frequent utilization of inclined and eccentric geosynchronous orbits. Consequently, the nature of the GEO regime and its immediate surroundings is evolving from well-known classical characteristics. This paper takes a fresh look at the GEO satellite population and the near- and far-term environmental implications of the region, including the effects of national and international debris mitigation measures.

  10. Numerical simulation of the operation of a MHD generator in transient regimes in MHD power stations

    SciTech Connect

    Bityurin, V.A.; Ivanov, P.P.; Koryagina, G.M.; Lyubimov, G.A.; Medin, S.A.; Morozov, G.N.; Prokop, A.S.

    1982-09-01

    Transient regimes of a MHD generator operating in combination with equipment in a MHD power station are analzyed with the help of a numerical model. The MHD generator, whose flow-through part consists of a nozzle, a channel, and a diffuser, is regulated by changing the flow rate and the load. Three types of MHD channels are studied: Faraday supersonic and subsonic, and diagonal supersonic. Their characteristics are presented and the efficiency of the MHD power station under nonrated regimes is determined. It is established that a MHD generator and the MHD power station as a whole admit quite efficient and deep regulation of the change in the flow rate of the working body.

  11. The quiescent H-mode regime for high performance edge localized mode-stable operation in future burning plasmas

    SciTech Connect

    Garofalo, A. M. Burrell, K. H.; Meneghini, O.; Osborne, T. H.; Paz-Soldan, C.; Smith, S. P.; Snyder, P. B.; Turnbull, A. D.; Eldon, D.; Grierson, B. A.; Solomon, W. M.; Hanson, J. M.; Holland, C.; Huijsmans, G. T. A.; Liu, F.; Loarte, A.; Zeng, L.

    2015-05-15

    For the first time, DIII-D experiments have achieved stationary quiescent H-mode (QH-mode) operation for many energy confinement times at simultaneous ITER-relevant values of beta, confinement, and safety factor, in an ITER-like shape. QH-mode provides excellent energy confinement, even at very low plasma rotation, while operating without edge localized modes (ELMs) and with strong impurity transport via the benign edge harmonic oscillation (EHO). By tailoring the plasma shape to improve the edge stability, the QH-mode operating space has also been extended to densities exceeding 80% of the Greenwald limit, overcoming the long-standing low-density limit of QH-mode operation. In the theory, the density range over which the plasma encounters the kink-peeling boundary widens as the plasma cross-section shaping is increased, thus increasing the QH-mode density threshold. The DIII-D results are in excellent agreement with these predictions, and nonlinear magnetohydrodynamic analysis of reconstructed QH-mode equilibria shows unstable low n kink-peeling modes growing to a saturated level, consistent with the theoretical picture of the EHO. Furthermore, high density operation in the QH-mode regime has opened a path to a new, previously predicted region of parameter space, named “Super H-mode” because it is characterized by very high pedestals that can be more than a factor of two above the peeling-ballooning stability limit for similar ELMing H-mode discharges at the same density.

  12. Large-mode-area fibers operating near single-mode regime.

    PubMed

    Kong, Fanting; Dunn, Christopher; Parsons, Joshua; Kalichevsky-Dong, Monica T; Hawkins, Thomas W; Jones, Maxwell; Dong, Liang

    2016-05-16

    Lower NA in large-mode-area fibers enables better single-mode operation and larger core diameters. Fiber NA has traditionally been limited to 0.06, mostly due to the control tolerance in the fabrication process. It has been recognized recently that transverse mode instability is a major limit to average power scaling in fiber lasers. One effective method to mitigate this limit is to operate nearer to the single-mode regime. Lower fiber NA is critical in this since it allows relatively larger core diameters which is the key to mitigate the limits imposed by nonlinear effects. We have developed a fabrication process of ytterbium-doped silica glass which is capable of highly accurate refractive index control and sufficient uniformity for LMA fibers. This process is also capable of large-volume production. It is based on a significant amount of post-processing once the fiber preforms are made. We have demonstrated 30/400 and 40/400 LMA fibers with a NA of ~0.028 operating very close to the single-mode regime. The second-order mode cuts off at ~1.2μm and ~1.55µm respectively. We have also studied issues related to bend losses due to the low NA and further optimization of LMA fibers. PMID:27409854

  13. Administrative aspects of a general surgical firm: an audit of accuracy of operation lists and timeliness of discharge summaries.

    PubMed

    Aziz, M M; Corder, A P

    1996-07-01

    A one-year audit of operation lists and discharge summaries of one surgical firm showed only 1.4 percent of operation lists contained errors or omissions and only 5 percent contained abbreviations. 74.2 percent of discharge summaries were dictated within one week of discharge. A high proportion of day cases allowed 44.7 percent of the discharge summaries to be dictated on the day of operation. Close consultant and secretarial involvement in the preparation of operating lists can ensure a high degree of accuracy. Day case operation notes should be combined with a discharge letter to optimise communication with general practitioners. PMID:8943624

  14. Enhancement of the EUV emission of a metallic capillary discharge operated with argon ambient gas

    SciTech Connect

    Chan, L. S. Tan, D. Saboohi, S. Yap, S. L. Wong, C. S.

    2014-03-05

    In this work, the metallic capillary discharge is operated with two different ambients: air and argon. In the experiments reported here, the chamber is first evacuated to 10{sup −5} mbar. The discharge is initiated by the transient hollow cathode effect generated electron beam, with either air ambient or argon ambient at 10{sup −4} mbar. The bombardment of electron beam at the tip of the stainless steel anode gives rise to a metallic vapor, which is injected into the capillary and initiates the main discharge through the capillary. The EUV emission is measured for different discharge voltages for both conditions and compared. It is found that the metallic capillary discharge with argon ambientis able to produce higher EUV energy compared to that with air ambient.

  15. Enhanced focus steering abilities of multi-element therapeutic arrays operating in nonlinear regimes

    SciTech Connect

    Yuldashev, P. Ilyin, S.; Gavrilov, L.; Sapozhnikov, O.; Khokhlova, V.; Kreider, W.

    2015-10-28

    Steering abilities of a typical HIFU therapeutic array operated in linear and nonlinear regimes were compared using numerical simulation with the 3D Westervelt equation. The array included 256 elements of 1.2 MHz frequency and 6.6 mm diameter distributed in a quasi-random pattern over a spherical shell with a 130 mm aperture and a focal length of 120 mm. In the case of linear focusing, thermal effects are proportional to the intensity level and the criterion for safe array operation is that the intensity in the grating lobes should be less than 10% of the intensity in the main focus. In the case of nonlinear focusing, the heating effect is no longer proportional to intensity; therefore the heat deposition rate was chosen as the relevant metric, using the same 10% threshold for the secondary lobe in comparison with the focal maximum. When steering the focus, the same linearly predicted intensity level at the main focus was maintained by increasing the array power. Numerical simulations of the acoustic field were performed for nonlinear propagation both in water and in tissue. It was shown that for shock-forming conditions in the main focus, the steering range of safe electronic focusing is larger than that for linear propagation conditions. Nonlinear sonication regimes therefore can be used to enlarge tissue volumes that can be sonicated using electronic steering of the focus of HIFU arrays.

  16. Enhanced focus steering abilities of multi-element therapeutic arrays operating in nonlinear regimes

    NASA Astrophysics Data System (ADS)

    Yuldashev, P.; Ilyin, S.; Gavrilov, L.; Sapozhnikov, O.; Kreider, W.; Khokhlova, V.

    2015-10-01

    Steering abilities of a typical HIFU therapeutic array operated in linear and nonlinear regimes were compared using numerical simulation with the 3D Westervelt equation. The array included 256 elements of 1.2 MHz frequency and 6.6 mm diameter distributed in a quasi-random pattern over a spherical shell with a 130 mm aperture and a focal length of 120 mm. In the case of linear focusing, thermal effects are proportional to the intensity level and the criterion for safe array operation is that the intensity in the grating lobes should be less than 10% of the intensity in the main focus. In the case of nonlinear focusing, the heating effect is no longer proportional to intensity; therefore the heat deposition rate was chosen as the relevant metric, using the same 10% threshold for the secondary lobe in comparison with the focal maximum. When steering the focus, the same linearly predicted intensity level at the main focus was maintained by increasing the array power. Numerical simulations of the acoustic field were performed for nonlinear propagation both in water and in tissue. It was shown that for shock-forming conditions in the main focus, the steering range of safe electronic focusing is larger than that for linear propagation conditions. Nonlinear sonication regimes therefore can be used to enlarge tissue volumes that can be sonicated using electronic steering of the focus of HIFU arrays.

  17. Ultra Low Power Full Digital Body Temperature Sensor Operating in Sub-Threshold Regime

    NASA Astrophysics Data System (ADS)

    Wu, Yuping; Zhang, Xuelian; Chen, Lan

    2015-11-01

    In this paper, we presented a full digital human body temperature sensor with high yield, which was designed in 40 nm CMOS technology. As part of the green BAN, it can measure the body temperature with ultra-low-power in high accuracy by operating in deep sub-threshold regime. The power dissipation is 1.2 nW with a power supply voltage of 0.12 V at 27 °C. The accuracy is 0.047 °C in the temperature range from 25 to 45 °C, and the sensor can operate with the power supply range from 0.12 to 0.40 V and takes ultra-low-power consumption.

  18. Statistical properties of the radiation from SASE FEL operating in a post-saturation regime with and without undulator tapering

    NASA Astrophysics Data System (ADS)

    Schneidmiller, E. A.; Yurkov, M. V.

    2016-02-01

    We describe statistical and coherence properties of the radiation from X-ray free-electron lasers (XFEL) operating in the post-saturation regime. We consider the practical case of the SASE3 FEL at the European XFEL. We perform comparison of the main characteristics of the X-ray FEL operating in the post-saturation regime with and without undulator tapering: efficiency, coherence time, and degree of transverse coherence.

  19. Scheduling hydro power systems with restricted operating zones and discharge ramping constraints

    SciTech Connect

    Guan, X.; Svoboda, Al; Li, C.

    1999-02-01

    An optimization-based algorithm is presented for scheduling hydro power systems with restricted operating zones and discharge ramping constraints. Hydro watershed scheduling problems are difficult to solve because many constraints, continuous and discrete, including hydraulic coupling of cascaded reservoirs have to be considered. Restricted or forbidden operating zones as well as minimum generation limits of hydro units result in discontinuous preferred operating regions, and hinder direct applications of efficient continuous optimization methods such as network flow algorithms. Discharge ramping constraints due to navigational, environmental and recreational requirements in a hydro system add another dimension of difficulty since they couple generation or water discharge across time horizon. The key idea of this paper is to use additional sets of multipliers to relax discontinuous operating region and discharge ramping constraints on individual hydro units so that a two-level optimization structure is formed. The low level consists of a continuous discharge scheduling subproblem determining the generation levels of all units in the entire watershed, and a number of pure integer scheduling subproblems determining the hydro operating states, one for each unit. The discharge subproblem is solved by a network flow algorithm, and the integer scheduling problems are solved by dynamic programming with a small number of states and well-structured transitions. The two sets of subproblems are coordinated through multipliers updated at the high level by using a modified subgradient algorithm. After the dual problem converges, a feasible hydro schedule is obtained by using the same network flow algorithm with the operating states obtained, and operating ranges modified to guarantee satisfaction of ramping constraints.

  20. Design optimization for plasma performance and assessment of operation regimes in JT-60SA

    NASA Astrophysics Data System (ADS)

    Fujita, T.; Tamai, H.; Matsukawa, M.; Kurita, G.; Bialek, J.; Aiba, N.; Tsuchiya, K.; Sakurai, S.; Suzuki, Y.; Hamamatsu, K.; Hayashi, N.; Oyama, N.; Suzuki, T.; Navratil, G. A.; Kamada, Y.; Miura, Y.; Takase, Y.; Campbell, D.; Pamela, J.; Romanelli, F.; Kikuchi, M.

    2007-11-01

    The design of the modification of JT-60U, JT-60SA has been optimized from the viewpoint of plasma performance, and operation regimes have been evaluated with the latest design. Upper and lower divertors with different geometries will be prepared for flexibility of the plasma shape, which will enable both low aspect ratio (A ~ 2.65) and ITER shape (A = 3.1) configurations. The beam lines of negative-ion neutral beam injection will be shifted downwards by ~0.6 m for the off-axis current drive (CD), in order to obtain a weak/reversed shear plasma, as well as having the capability of heating the central region. The feedback control coils along the openings in the stabilizing plate are found effective in suppressing the resistive wall mode and sustaining high βN close to the ideal wall limit. Sustainment of plasma current of 3-3.5 MA for 100 s will be possible in ELMy H-mode plasmas with moderate heating power, βN, and density within an available flux swing. It is also expected that higher βN, high-density ELMy H-mode plasmas will be maintained for 100 s with higher heating power. The expected regime of full CD operation has been extended with upgraded heating and CD power. Full CD operation for 100 s with reactor-relevant high values of normalized beta and bootstrap current fraction (Ip = 2.4 MA, βN = 4.3, fBS = 0.69, \\bar{n}_{\\rme}/n_GW = 0.86 , HH98y2 = 1.3) is expected in a highly-shaped low-aspect-ratio configuration (A = 2.65).

  1. Validation of mathematical models for predicting the swirling flow and the vortex rope in a Francis turbine operated at partial discharge

    NASA Astrophysics Data System (ADS)

    Kuibin, P. A.; Okulov, V. L.; Susan-Resiga, R. F.; Muntean, S.

    2010-08-01

    The vortex rope in a hydro turbine draft tube is one the main and strong sources of pulsations in non-optimal modes of hydro turbine operation. We examine the case of a Francis turbine model operated at partial discharge, where a strong precessing vortex rope is developed in the discharge cone downstream the runner. Available experimental data provide the circumferentially averaged axial and circumferential velocity profiles, as well as the vortex rope geometry, precessing frequency, and the level of pressure fluctuation at the wall. The mathematical models presented in this paper can correctly recover all this information without actually computing the full three-dimensional unsteady flow in the hydraulic turbine. As a result, we provide valuable mathematical tools for assessing the turbine behaviour at off-design operating regimes in the early stages of runner design, with computational effort several orders of magnitude less than the current approaches of simulating the complex turbine flow.

  2. ZnO Nanowire-Based Corona Discharge Devices Operated Under Hundreds of Volts

    NASA Astrophysics Data System (ADS)

    Yang, Wenming; Zhu, Rong; Zong, Xianli

    2016-02-01

    Minimizing the voltage of corona discharges, especially when using nanomaterials, has been of great interest in the past decade or so. In this paper, we report a new corona discharge device by using ZnO nanowires operated in atmospheric air to realize continuous corona discharge excited by hundreds of volts. ZnO nanowires were synthesized on microelectrodes using electric-field-assisted wet chemical method, and a thin tungsten film was deposited on the microchip to enhance discharging performance. The testing results showed that the corona inception voltages were minimized greatly by using nanowires compared to conventional dischargers as a result of the local field enhancement of nanowires. The corona could be continuously generated and self-sustaining. It was proved that the law of corona inception voltage obeyed the conventional Peek's breakdown criterion. An optimal thickness of tungsten film coated over ZnO nanowires was figured out to obtain the lowest corona inception voltage. The ion concentration of the nanowire-based discharger attained 1017/m3 orders of magnitude, which is practicable for most discharging applications.

  3. ZnO Nanowire-Based Corona Discharge Devices Operated Under Hundreds of Volts.

    PubMed

    Yang, Wenming; Zhu, Rong; Zong, Xianli

    2016-12-01

    Minimizing the voltage of corona discharges, especially when using nanomaterials, has been of great interest in the past decade or so. In this paper, we report a new corona discharge device by using ZnO nanowires operated in atmospheric air to realize continuous corona discharge excited by hundreds of volts. ZnO nanowires were synthesized on microelectrodes using electric-field-assisted wet chemical method, and a thin tungsten film was deposited on the microchip to enhance discharging performance. The testing results showed that the corona inception voltages were minimized greatly by using nanowires compared to conventional dischargers as a result of the local field enhancement of nanowires. The corona could be continuously generated and self-sustaining. It was proved that the law of corona inception voltage obeyed the conventional Peek's breakdown criterion. An optimal thickness of tungsten film coated over ZnO nanowires was figured out to obtain the lowest corona inception voltage. The ion concentration of the nanowire-based discharger attained 10(17)/m(3) orders of magnitude, which is practicable for most discharging applications. PMID:26880727

  4. Studying of negative ions source based on reflective discharge in regimes with cesium added and without cesium

    SciTech Connect

    Soloshenko, I. A.; Shchedrin, A. I.; Ryabtsev, A. V.

    1998-08-20

    The results of theoretical and experimental studies of physical processes in the source of hydrogen negative ions are presented. The source is based on reflective discharge with incandescent cathode and H{sup -} ions extraction across magnetic field. Calculations of gas discharge plasma parameters for given current and energy of electrons emitted from the cathode are performed in theoretical part of the proceeding. Plasma parameters, including H{sup -} ions concentration, are determined on a basis of Boltzman equation solution taking into consideration principal collision reactions in a volume and at a surface of the discharge chamber.

  5. Discharge product morphology versus operating temperature in non-aqueous lithium-air batteries

    NASA Astrophysics Data System (ADS)

    Tan, P.; Shyy, W.; Zhao, T. S.; Wei, Z. H.; An, L.

    2015-03-01

    During the discharge process of non-aqueous lithium-air batteries, a solid product, Li2O2, forms in the pores of the porous cathode, and eventually causes the discharge process to cease. During the charge process, solid Li2O2 needs to be electrochemically oxidized. The morphology of the discharge product is, therefore, critically related to the capacity and reversibility of the battery. In this work, we experimentally show that for a given design of the cathode, the shape of the discharge product Li2O2 at a given discharge current density remains almost unchanged with a change in the operating temperature, but the size decreases with an increase in the temperature. We also demonstrate that the product shape varies with the discharge current density at a given temperature. The practical implication of these findings is that the capacity, charge voltage, and cyclability of a given non-aqueous lithium-air battery are affected by the operating temperature.

  6. Operating Spin Echo in the Quantum Regime for an Atomic-Ensemble Quantum Memory.

    PubMed

    Rui, Jun; Jiang, Yan; Yang, Sheng-Jun; Zhao, Bo; Bao, Xiao-Hui; Pan, Jian-Wei

    2015-09-25

    Spin echo is a powerful technique to extend atomic or nuclear coherence times by overcoming the dephasing due to inhomogeneous broadenings. However, there are disputes about the feasibility of applying this technique to an ensemble-based quantum memory at the single-quanta level. In this experimental study, we find that noise due to imperfections of the rephasing pulses has both intense superradiant and weak isotropic parts. By properly arranging the beam directions and optimizing the pulse fidelities, we successfully manage to operate the spin echo technique in the quantum regime by observing nonclassical photon-photon correlations as well as the quantum behavior of retrieved photons. Our work for the first time demonstrates the feasibility of harnessing the spin echo method to extend the lifetime of ensemble-based quantum memories at the single-quanta level. PMID:26451551

  7. A new high performance field reversed configuration operating regime in the C-2 device

    SciTech Connect

    Tuszewski, M.; Smirnov, A.; Thompson, M. C.; Barnes, D.; Binderbauer, M. W.; Brown, R.; Bui, D. Q.; Clary, R.; Conroy, K. D.; Deng, B. H.; Dettrick, S. A.; Douglass, J. D.; Garate, E.; Glass, F. J.; Gota, H.; Guo, H.Y.; Gupta, D.; Gupta, S.; Kinley, J. S.; Knapp, K.; and others

    2012-05-15

    Large field reversed configurations (FRCs) are produced in the C-2 device by combining dynamic formation and merging processes. The good confinement of these FRCs must be further improved to achieve sustainment with neutral beam (NB) injection and pellet fuelling. A plasma gun is installed at one end of the C-2 device to attempt electric field control of the FRC edge layer. The gun inward radial electric field counters the usual FRC spin-up and mitigates the n = 2 rotational instability without applying quadrupole magnetic fields. Better plasma centering is also obtained, presumably from line-tying to the gun electrodes. The combined effects of the plasma gun and of neutral beam injection lead to the high performance FRC operating regime, with FRC lifetimes up to 3 ms and with FRC confinement times improved by factors 2 to 4.

  8. Experimental researches of fiber Bragg gratings operating in a few-mode regime

    NASA Astrophysics Data System (ADS)

    Kafarova, Anastasia M.; Faskhutdinov, Lenar M.; Kuznetzov, Artem A.; Minaeva, Alina Y.; Sevruk, Nikita L.; Nureev, Ilnur I.; Vasilets, Alexander A.; Bourdine, Anton V.; Morozov, Oleg G.; Burdin, Vladimir A.

    2016-03-01

    This work presents results of experimental researches of fiber Bragg gratings (FBG) operating in a few-mode regime. We tested FBGs written on silica graded-index multimode fibers 50/125 Cat. OM2+/OM3 with Bragg wavelength 1550 nm by using them in a set of developed experimental schemes based on excitation of multimode fibers by corresponding laser sources. The researches were focused on analysis of both spectral and pulse responses under changing of selected mode mixing and power diffusion processes due to tension and/or stress local and distributed action to FBG or sensor fiber. Results of spectral and pulse response measurements at the output of schemes with installed described FBGs are represented.

  9. Influence of Reservoir Operation on River Eco-hydrological Regime Variation

    NASA Astrophysics Data System (ADS)

    Chang, J.; Wang, Y.; Li, Y.

    2013-12-01

    With the development of reservoir, river hydrological situation has undergone great changes. Liujiaxia and Longyangxia reservoir which all have great regulation ability were constructed in the upper reaches above Lanzhou station of the Yellow River. In view of the Indicator of Hydrologic Alteration (IHA), the Range of Variability Approach ( RVA ) is used to calculate the eco- hydrological characteristic values and analyze the influence of different reservoir operating modes on the variation of eco-hydrological characteristics of the Yellow River upstream. On the whole, the hydrologic regime at each station downstream of the Liujiaxia reservoir has changed obviously, especially that at Lanzhou station. The overall degree of hydrologic alteration with single reservoir (Liujiaxia) was 72. 64%, and the hydrologic alteration degree with two reservoirs joint operation was 78. 90%. Both of them were belong to high change. Also, after joint operation of Liujiaxia and Longyangxia reservoir, the flow in flood season significantly reduce and the number of high and low flow reversals increase, which would influence the living condition of aquatic organism in the Yellow River, and greatly endanger the aquatic species' reproduction.

  10. Clogging of Joule-Thomson Devices in Liquid Hydrogen-Lunar Lander Descent Stage Operating Regime

    NASA Astrophysics Data System (ADS)

    Jurns, J. M.

    2010-04-01

    Joule-Thomson (J-T) devices have been identified as critical components for future space exploration missions. The NASA Constellation Program lunar architecture considers LOX/LH2 propulsion for the lunar lander descent stage main engine an enabling technology, ensuring the cryogenic propellants are available at the correct conditions for engine operation. This cryogenic storage system may utilize a Thermodynamic Vent System (TVS) that includes J-T devices to maintain tank fluid pressure and temperature. Previous experimental investigations have indicated that J-T devices may become clogged when flowing LH2 while operating at a temperature range from 20.5 K to 24.4 K. It has been proposed that clogging is due to a trace amount of metastable, supercooled liquid neon in the regular LH2 supply. In time, flow blockage occurs from accretion of solid neon on the orifice. This clogging poses a realistic threat to spacecraft propulsion systems utilizing J-T devices in cryogenic pressure control systems. TVS failure due to J-T clogging would prevent removal of environmental heat from the propellant and potential loss of mission. This report describes J-T clogging tests performed with LH2. Tests were performed in the expected Lunar Lander operating regime, and several methods were evaluated to determine the optimum approach to mitigating the potential risk of J-T clogging.

  11. Basal Resources in Backwaters of the Colorado River Below Glen Canyon Dam-Effects of Discharge Regimes and Comparison with Mainstem Depositional Environments

    USGS Publications Warehouse

    Behn, Katherine E.; Kennedy, Theodore A.; Hall, Robert O., Jr.

    2010-01-01

    Eight species of fish were native to the Colorado River before the closure of Glen Canyon Dam, but only four of these native species are currently present. A variety of factors are responsible for the loss of native fish species and the limited distribution and abundance of those that remain. These factors include cold and constant water temperatures, predation and competition with nonnative fish species, and food limitation. Backwaters are areas of stagnant flow in a return-current channel and are thought to be critical rearing habitat for juvenile native fish. Backwaters can be warmer than the main channel and may support higher rates of food production. Glen Canyon Dam is a peaking hydropower facility and, as a result, has subdaily variation in discharge because of changes in demand for power. Stable daily discharges may improve the quality of nearshore rearing habitats such as backwaters by increasing warming, stabilizing the substrate, and increasing food production. To evaluate whether backwaters have greater available food resources than main-channel habitats, and how resource availability in backwaters is affected by stable flow regimes, we quantified water-column and benthic food resources in backwaters seasonally for 1 year using both standing (organic matter concentration/density; chlorophyll a concentration/density; zooplankton concentration; benthic invertebrate density and biomass) and process measurements (chamber estimates of ecosystem metabolism). We compared backwater resource measurements with comparable data from main-channel habitats, and compared backwater data collected during stable discharge with data collected when there was subdaily variation in discharge. Rates of primary production in backwaters (mean gross primary production of 1.7 g O2/m2/d) and the main channel (mean gross primary production of 2.0 g O2/m2/d) were similar. Benthic organic matter standing stock (presented as ash-free dry mass-AFDM) was seven times higher in backwaters

  12. Effects of dam operation on the endangered Júcar nase, Parachondrostoma arrigonis, related to mesohabitats, microhabitat availability and water temperature regime, in the river Cabriel (Spain)

    NASA Astrophysics Data System (ADS)

    Martinez-Capel, Francisco; Costa, Rui; Muñoz-Mas, Rafael; Diego Alcaraz-Hernandez, Juan; Hernandez-Mascarell, Aina

    2010-05-01

    The presence of large dams affects habitat availability, often regarded as the primary factor that limits population and community recovery in rivers. Physical habitat is often targeted in restoration, but there is often a paucity of useful information. Habitat degradation has reduced the complexity and connectivity of the Mediterranean streams in Spain. These changes have diminished the historical range of the endangered Júcar nase, Parachondrostoma arrigonis (Steindachner, 1866), isolated the populations of this species, and probably contributed to its risk of extinction. In the Júcar River basin (Spain), where this fish is endemic, the populations are mainly restricted to the river Cabriel, which is fragmented in two segments by the large dam of Contreras. In this river, 3 main lines of research were developed from 2006 to 2008, i.e., microhabitat suitability, mesohabitat suitability, and water temperature, in order to relate such kind of variables with the flow regime. The main goal of the research project, funded by the Spanish Ministry of Environment, was to detect the main reasons of the species decline, and to propose dam operation improvements to contribute to the recovery of the species. The flow and water temperature regimes were also studied in the river Cabriel, upstream and downstream the large dam of Contreras. During the three years of study, below the dam it was observed a small and not significant variation in the proportions of slow and fast habitats; the regulated flow regime was pointed out as the main reason of such variations. At the microhabitat scale, optimal ranges for average depth and velocity were defined; these data allowed us to develop an estimation of weighted useable area under natural and regulated conditions. The Júcar nase were found majorly at depths no greater than 1,15 meters with slow water velocities. It was possible to observe a clear alteration of the flow and water temperature regime below the dam, due to the cold

  13. 20 CFR 726.207 - Discharge by the carrier of obligations and duties of operator.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 20 Employees' Benefits 4 2014-04-01 2014-04-01 false Discharge by the carrier of obligations and duties of operator. 726.207 Section 726.207 Employees' Benefits OFFICE OF WORKERS' COMPENSATION PROGRAMS, DEPARTMENT OF LABOR FEDERAL COAL MINE HEALTH AND SAFETY ACT OF 1969, AS AMENDED BLACK LUNG...

  14. 20 CFR 726.207 - Discharge by the carrier of obligations and duties of operator.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 20 Employees' Benefits 4 2013-04-01 2013-04-01 false Discharge by the carrier of obligations and duties of operator. 726.207 Section 726.207 Employees' Benefits OFFICE OF WORKERS' COMPENSATION PROGRAMS, DEPARTMENT OF LABOR FEDERAL COAL MINE HEALTH AND SAFETY ACT OF 1969, AS AMENDED BLACK LUNG...

  15. 20 CFR 726.207 - Discharge by the carrier of obligations and duties of operator.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 20 Employees' Benefits 4 2012-04-01 2012-04-01 false Discharge by the carrier of obligations and duties of operator. 726.207 Section 726.207 Employees' Benefits OFFICE OF WORKERS' COMPENSATION PROGRAMS, DEPARTMENT OF LABOR FEDERAL COAL MINE HEALTH AND SAFETY ACT OF 1969, AS AMENDED BLACK LUNG...

  16. 33 CFR 151.73 - Operating requirements: Discharge of garbage from fixed or floating platforms.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Operating requirements: Discharge of garbage from fixed or floating platforms. 151.73 Section 151.73 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION VESSELS CARRYING OIL, NOXIOUS LIQUID SUBSTANCES, GARBAGE, MUNICIPAL OR...

  17. 33 CFR 151.71 - Operating requirements: Discharge of garbage within special areas.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Operating requirements: Discharge of garbage within special areas. 151.71 Section 151.71 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION VESSELS CARRYING OIL, NOXIOUS LIQUID SUBSTANCES, GARBAGE, MUNICIPAL OR COMMERCIAL WASTE,...

  18. 33 CFR 151.69 - Operating requirements: Discharge of garbage outside special areas.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Operating requirements: Discharge of garbage outside special areas. 151.69 Section 151.69 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION VESSELS CARRYING OIL, NOXIOUS LIQUID SUBSTANCES, GARBAGE, MUNICIPAL OR COMMERCIAL WASTE,...

  19. 33 CFR 151.69 - Operating requirements: Discharge of garbage outside special areas.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Operating requirements: Discharge of garbage outside special areas. 151.69 Section 151.69 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION VESSELS CARRYING OIL, NOXIOUS LIQUID SUBSTANCES, GARBAGE, MUNICIPAL OR COMMERCIAL WASTE,...

  20. Progress Toward Steady State Tokamak Operation Exploiting the high bootstrap current fraction regime

    NASA Astrophysics Data System (ADS)

    Ren, Q.

    2015-11-01

    Recent DIII-D experiments have advanced the normalized fusion performance of the high bootstrap current fraction tokamak regime toward reactor-relevant steady state operation. The experiments, conducted by a joint team of researchers from the DIII-D and EAST tokamaks, developed a fully noninductive scenario that could be extended on EAST to a demonstration of long pulse steady-state tokamak operation. Fully noninductive plasmas with extremely high values of the poloidal beta, βp >= 4 , have been sustained at βT >= 2 % for long durations with excellent energy confinement quality (H98y,2 >= 1 . 5) and internal transport barriers (ITBs) generated at large minor radius (>= 0 . 6) in all channels (Te, Ti, ne, VTf). Large bootstrap fraction (fBS ~ 80 %) has been obtained with high βp. ITBs have been shown to be compatible with steady state operation. Because of the unusually large ITB radius, normalized pressure is not limited to low βN values by internal ITB-driven modes. βN up to ~4.3 has been obtained by optimizing the plasma-wall distance. The scenario is robust against several variations, including replacing some on-axis with off-axis neutral beam injection (NBI), adding electron cyclotron (EC) heating, and reducing the NBI torque by a factor of 2. This latter observation is particularly promising for extension of the scenario to EAST, where maximum power is obtained with balanced NBI injection, and to a reactor, expected to have low rotation. However, modeling of this regime has provided new challenges to state-of-the-art modeling capabilities: quasilinear models can dramatically underpredict the electron transport, and the Sauter bootstrap current can be insufficient. The analysis shows first-principle NEO is in good agreement with experiments for the bootstrap current calculation and ETG modes with a larger saturated amplitude or EM modes may provide the missing electron transport. Work supported in part by the US DOE under DE-FC02-04ER54698, DE-AC52-07NA

  1. Progress toward steady-state tokamak operation exploiting the high bootstrap current fraction regime

    NASA Astrophysics Data System (ADS)

    Ren, Q. L.; Garofalo, A. M.; Gong, X. Z.; Holcomb, C. T.; Lao, L. L.; McKee, G. R.; Meneghini, O.; Staebler, G. M.; Grierson, B. A.; Qian, J. P.; Solomon, W. M.; Turnbull, A. D.; Holland, C.; Guo, W. F.; Ding, S. Y.; Pan, C. K.; Xu, G. S.; Wan, B. N.

    2016-06-01

    Recent DIII-D experiments have increased the normalized fusion performance of the high bootstrap current fraction tokamak regime toward reactor-relevant steady state operation. The experiments, conducted by a joint team of researchers from the DIII-D and EAST tokamaks, developed a fully noninductive scenario that could be extended on EAST to a demonstration of long pulse steady-state tokamak operation. Improved understanding of scenario stability has led to the achievement of very high values of βp and βN , despite strong internal transport barriers. Good confinement has been achieved with reduced toroidal rotation. These high βp plasmas challenge the energy transport understanding, especially in the electron energy channel. A new turbulent transport model, named TGLF-SAT1, has been developed which improves the transport prediction. Experiments extending results to long pulse on EAST, based on the physics basis developed at DIII-D, have been conducted. More investigations will be carried out on EAST with more additional auxiliary power to come online in the near term.

  2. Effect of the river discharge implementation in an operational model for the West Iberia coastal area.

    NASA Astrophysics Data System (ADS)

    Campuzano, Francisco; Brito, David; Juliano, Manuela; Fernandes, Rodrigo; Neves, Ramiro

    2015-04-01

    In the Iberian Peninsula, most of the largest rivers discharge on the Atlantic coast draining almost two thirds of the territory. It is an important source of nutrients and sediments to these coastal areas. Rivers discharges in the Atlantic area when compared with the ones in the Mediterranean side present the particularity that their water before is released into the ocean is previously mixed in their estuaries in a different ratio depending of the estuarine residence time and the discharged flow. In order to evaluate the relative importance of the inland waters in the circulation patterns of Western Iberia, the rivers discharges were implemented in the PCOMS model application (Portuguese Coast Operational Modelling System). To reproduce the water continuum including the different spatial and temporal scales, a methodology consisting in a system of integrated models using the Mohid model was designed. At the watershed level, the Mohid Land model calculated operationally water flow and properties, including nutrients, for the main river catchments of Western Iberian with a 2 km horizontal resolution. Downstream, several operational hydrodynamic and biological estuarine applications used those outcomes as model inputs, filling the gaps in the observation network. From the estuarine models, the tidally modulated water and properties fluxes to the coast were obtained. These fluxes were finally imposed in the Portuguese Coast Operational Modelling System (PCOMS), a fully 3D baroclinic hydrodynamic and ecological regional model that covers the Iberian Atlantic front. The fate of the rivers discharges were analysed by integrating model results in boxes, comparing the climatologies obtained with and without rivers and the rivers area of influence was obtained by lagrangian tracers simulations.

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

    NASA Astrophysics Data System (ADS)

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

    2011-02-01

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

  4. The effect of submarine groundwater discharge on nutrient and salinity regimes in a coastal lagoon off Perth, Western Australia

    NASA Astrophysics Data System (ADS)

    Johannes, R. E.; Hearn, C. J.

    1985-12-01

    Submarine groundwater discharge (SGD) into a coastal lagoon off Perth, Western Australia, contains nitrate and silicate in concentrations two orders of magnitude higher than those of the receiving waters. This discharge delivers enough nitrate to replace that dissolved in the lagoon water mass about every eight days and enough silicate to replace the lagoon silicate in about 48 days. The delivery rate of nitrate nitrogen by SGD is equal to about 48% of that required for observed growth rates of lagoon macrophytes. Surface salinity is lower close to the shore as a result of SGD. During calm conditions a salinity front was observed in the lagoon, with a nearshore pool of nutrient-enriched water floating above the more saline ocean water.

  5. Analyzing the discharge regime of a large tropical river through remote sensing, ground-based climatic data, and modeling

    NASA Astrophysics Data System (ADS)

    VöRöSmarty, Charles J.; Willmott, Cort J.; Choudhury, Bhaskar J.; Schloss, Annette L.; Stearns, Timothy K.; Robeson, Scott M.; Dorman, Timothy J.

    1996-10-01

    This study demonstrates the potential for applying passive microwave satellite sensor data to infer the discharge dynamics of large river systems using the main stem Amazon as a test case. The methodology combines (1) interpolated ground-based meteorological station data, (2) horizontally and vertically polarized temperature differences (HVPTD) from the 37-GHz scanning multichannel microwave radiometer (SMMR) aboard the Nimbus 7 satellite, and (3) a calibrated water balance/water transport model (WBM/WTM). Monthly HVPTD values at 0.25° (latitude by longitude) resolution were resampled spatially and temporally to produce an enhanced HVPTD time series at 0.5° resolution for the period May 1979 through February 1985. Enhanced HVPTD values were regressed against monthly discharge derived from the WBM/WTM for each of 40 grid cells along the main stem over a calibration period from May 1979 to February 1983 to provide a spatially contiguous estimate of time-varying discharge. HVPTD-estimated flows generated for a validation period from March 1983 to February 1985 were found to be in good agreement with both observed arid modeled discharges over a 1400-km section of the main stem Amazon. This span of river is bounded downstream by a region of tidal influence and upstream by low sensor response associated with dense forest canopy. Both the WBM/WTM and HVPTD-derived flow rates reflect the significant impact of the 1982-1983 El Niño-;Southern Oscillation (ENSO) event on water balances within the drainage basin.

  6. Powerful electrostatic FEL: Regime of operation, recovery of the spent electron beam and high voltage generator

    SciTech Connect

    Boscolo, I.; Gong, J.

    1995-02-01

    FEL, driven by a Cockcroft-Walton electrostatic accelerator with the recovery of the spent electron beam, is proposed as powerful radiation source for plasma heating. The low gain and high gain regimes are compared in view of the recovery problem and the high gain regime is shown to be much more favourable. A new design of the onion Cockcroft-Walton is presented.

  7. High-efficiency FEL-oscillator with Bragg resonator operated in reversed guide field regime

    SciTech Connect

    Kaminsky, A.K.; Sedykh, S.N.; Sergeyev, A.P.

    1995-12-31

    The aim of the present work was to develop a narrow-band FEL-oscillator working in millimeter wavelength with, high efficiency. It looked promising to combine the high selective property of Bragg resonator with high efficiency and other advantages of FEL operation in the reversed guide-field regime. An experimental study of the FEL was performed using lilac LIU-3000 (JINR, Dubna) with the electron energy of 1 MeV, beam current up to 200 A and pulse duration of 200 ns. The beam was injected into the internction region with guide magnetic field of 2.9 kGs. Transverse oscillations of electrons were pumped by the helical wiggler with the period length of 6 cm and the field slowly up-tapering over the initial 6 periods. The FEI electrodynamic system consisted of a circular waveguide with diameter 20 mm and two Bragg reflectors. The H wave of the circular waveguide was shown for operation. Two effective feedback waves were observed in {open_quotes}cold{close_quotes} electrodynamic measurement in correspondence with calculations; the E wave near the frequency of 31. 5 GHz and the E wave - 37.5 GHz. The width of the both reflection resonances was about 2%. In {open_quotes}hot{close_quotes} experiments the radiation on the designed H wave and frequencies corresponding to the both feedback waves was registered separately. Selection of the frequency was realized by varying of the wiggler field strength. The spectrum was measured with a set of the cut--off waveguide filters with inaccuracy less than 2%. Calibrated Semiconductor detectors wire used to measure the radiation power. The radiation with the frequencies of 37.5 and 31.5 GHz was observed in vicinity of the wiggler field amplitude of 2.5 kGs. The measured spectrum width of the output FEL-oscillator radiation did not exceed the width of the Bragg reflector resonances for the both feedback waves.

  8. 46 CFR 153.1130 - Failure of slops discharge recording equipment; operating with, reporting failures, and replacing...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Failure of slops discharge recording equipment; operating with, reporting failures, and replacing pollution equipment: Category A, B, C, D. 153.1130 Section... slops discharge recording equipment; operating with, reporting failures, and replacing...

  9. 46 CFR 153.1130 - Failure of slops discharge recording equipment; operating with, reporting failures, and replacing...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Failure of slops discharge recording equipment; operating with, reporting failures, and replacing pollution equipment: Category A, B, C, D. 153.1130 Section... slops discharge recording equipment; operating with, reporting failures, and replacing...

  10. 46 CFR 153.1130 - Failure of slops discharge recording equipment; operating with, reporting failures, and replacing...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Failure of slops discharge recording equipment; operating with, reporting failures, and replacing pollution equipment: Category A, B, C, D. 153.1130 Section... slops discharge recording equipment; operating with, reporting failures, and replacing...

  11. 46 CFR 153.1130 - Failure of slops discharge recording equipment; operating with, reporting failures, and replacing...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Failure of slops discharge recording equipment; operating with, reporting failures, and replacing pollution equipment: Category A, B, C, D. 153.1130 Section... slops discharge recording equipment; operating with, reporting failures, and replacing...

  12. 46 CFR 153.1130 - Failure of slops discharge recording equipment; operating with, reporting failures, and replacing...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Failure of slops discharge recording equipment; operating with, reporting failures, and replacing pollution equipment: Category A, B, C, D. 153.1130 Section... slops discharge recording equipment; operating with, reporting failures, and replacing...

  13. Plasma characteristics of argon glow discharge produced by AC power supply operating at low frequencies

    SciTech Connect

    Kongpiboolkid, Watcharapon; Mongkolnavin, Rattachat

    2015-04-24

    Non-thermal properties of Argon glow discharge operating with various operating pressures were measured and presented in this work. The Argon plasma is produced by a parallel conducting electrodes coupling with a high voltage AC power supply. The power supply can generate high AC voltage at various frequencies. The frequencies for the operation are in the range of a few kHz. The system is capable of generating electric field between the two metal electrodes discharge system. The characteristics of plasma produced were measured by optical emission spectroscopy (OES) technique where electron temperature (T{sub e}) and electron number density (n{sub e}) can be determined by line intensity ratio method. The value of electron number density was then determined from the Saha-Eggert equation. Our results show that the electron number density of the discharge obtained is of the order of 10{sup −17} − 10{sup −18} m{sup −3} where the electron temperature is between 1.00−2.00 eV for various operating frequencies used which are in good agreement with similar results published earlier.

  14. Nanosecond pulses in a THz gyrotron oscillator operating in a mode-locked self-consistent Q-switch regime.

    PubMed

    Alberti, S; Braunmueller, F; Tran, T M; Genoud, J; Hogge, J-Ph; Tran, M Q; Ansermet, J-Ph

    2013-11-15

    An experimental study of a nanosecond pulsed regime in a THz gyrotron oscillator operating in a self-consistent Q-switch regime has been carried out. The gyrotron is operated in the TE(7,2) transverse mode radiating at a frequency of 260.5 GHz. The 5 W nanosecond pulses are obtained in a self-consistent Q-switch regime in which the cavity diffraction quality factor dynamically varies by nearly 2 orders of magnitude on a subnanosecond time scale via the nonlinear interaction of different mode-locked frequency-equidistant sidebands. The experimental results are in good agreement with numerical simulations performed with the TWANG code based on a slow time scale formulation of the self-consistent time-dependent nonlinear wave particle interaction equations. PMID:24289692

  15. Biological nutrient removal in a sequencing batch reactor operated as oxic/anoxic/extended-idle regime.

    PubMed

    Li, Xiao-ming; Chen, Hong-bo; Yang, Qi; Wang, Dong-bo; Luo, Kun; Zeng, Guang-ming

    2014-06-01

    Previous researches have demonstrated that biological phosphorus removal from wastewater could be induced by oxic/extended-idle (O/EI) regime. In this study, an anoxic period was introduced after the aeration to realize biological nutrient removal. High nitrite accumulation ratio and polyhydroxyalkanoates biosynthesis were obtained in the aeration and biological nutrient removal could be well achieved in oxic/anoxic/extended-idle (O/A/EI) regime for the wastewater used. In addition, nitrogen and phosphorus removal performance in O/A/EI regime was compared with that in conventional anaerobic/anoxic/aerobic (A(2)/O) and O/EI processes. The results showed that O/A/EI regime exhibited higher nitrogen and phosphorus removal than A(2)/O and O/EI processes. More ammonium oxidizing bacteria and polyphosphate accumulating organisms and less glycogen accumulating organisms containing in the biomass might be the principal reason for the better nitrogen and phosphorus removal in O/A/EI regime. Furthermore, biological nutrient removal with O/A/EI regime was demonstrated with municipal wastewater. The average TN, SOP and COD removal efficiencies were 93%, 95% and 87%, respectively. PMID:24393562

  16. Specific features of an electric discharge operating between an electrolytic anode and a metal cathode

    NASA Astrophysics Data System (ADS)

    Gaisin, A. F.; Sarimov, L. R.

    2011-06-01

    Results are presented from experimental studies of a high-current electric discharge operating between an St45 steel cathode and a service water anode in a wide range of air pressures. Peculiarities of discharge ignition and specific features of cathode and anode spots were revealed. The behavior of the current density on a service water anode was investigated for the first time. Comparison of the current densities j on the steel cathode and service water anode shows that, in the parameter range under study, Hehl's law is not satisfied on the water anode. The two-dimensional distribution of the potential inside and on the surface of the service water anode was measured.

  17. Pulsed Capillary Discharge Operated As A Compact Soft X-Ray Source

    NASA Astrophysics Data System (ADS)

    Valdivia, M. P.; Wyndham, E. S.; Favre, M.; Valenzuela, J. C.

    2010-07-01

    We analyze experimental results of radiation emission from a compact pulsed capillary ns discharge source, designed for soft x-ray applications, operated in Nitrogen and N/He mixtures at voltages in the range of 18-24kV. The discharge operates in an alumina capillary of length 21mm and 1.6mm inner diameter. The electrical energy stored is ~0.5 J with peak current of ~5kA. Fast charging from an IGBT based pulsed power circuit allows operation at 35-150 Hz. Characteristic time-integrated Nitrogen spectra were recorded from 10-220 Å with clear evidence of He-like Nitrogen line at 28.9 Å, which represents a possible source for a water window soft x-ray microscope. Time-evolution measurements show the influence of axial electron beams, generated by hollow cathode dynamics, on the x-ray emission. We discuss optimal frequency of operation, voltage applied, geometrical and pressure conditions for cathode and anode, for soft x-ray generation. Time-integrated MCP images of a filtered slit-wire system delivered an estimate of the maximum emission energy of our source, as well as clear evidence of full wall detachment, of ~100μm in radial size for the entire emission range.

  18. Proton acceleration by single-cycle laser pulses offers a novel monoenergetic and stable operating regime

    NASA Astrophysics Data System (ADS)

    Zhou, M. L.; Yan, X. Q.; Mourou, G.; Wheeler, J. A.; Bin, J. H.; Schreiber, J.; Tajima, T.

    2016-04-01

    Prompted by the possibility to produce high energy, single-cycle laser pulses with tens of Petawatt (PW) power, we have investigated laser-matter interactions in the few optical cycle and ultra relativistic intensity regimes. A particularly interesting instability-free regime for ion production was revealed leading to the efficient coherent generation of short (femtosecond; 10 - 15 s ) monoenergetic ion bunches with a peak energy greater than GeV. Of paramount importance, the interaction is absent of the Rayleigh Taylor Instabilities and hole boring that plague techniques such as target normal sheath acceleration and radiation pressure acceleration.

  19. Super H-mode: theoretical prediction and initial observations of a new high performance regime for tokamak operation

    NASA Astrophysics Data System (ADS)

    Snyder, P. B.; Solomon, W. M.; Burrell, K. H.; Garofalo, A. M.; Grierson, B. A.; Groebner, R. J.; Leonard, A. W.; Nazikian, R.; Osborne, T. H.; Belli, E. A.; Candy, J.; Wilson, H. R.

    2015-08-01

    A new ‘Super H-mode’ regime is predicted, which enables pedestal height and predicted fusion performance substantially higher than for H-mode operation. This new regime is predicted to exist by the EPED pedestal model, which calculates criticality constraints for peeling-ballooning and kinetic ballooning modes, and combines them to predict the pedestal height and width. EPED usually predicts a single (‘H-mode’) pedestal solution for each set of input parameters, however, in strongly shaped plasmas above a critical density, multiple pedestal solutions are found, including the standard ‘H-mode’ solution, and a ‘Super H-Mode’ solution at substantially larger pedestal height and width. The Super H-mode regime is predicted to be accessible by controlling the trajectory of the density, and to increase fusion performance for ITER, as well as for DEMO designs with strong shaping. A set of experiments on DIII-D has identified the predicted Super H-mode regime, and finds pedestal height and width, and their variation with density, in good agreement with theoretical predictions from the EPED model. The very high pedestal enables operation at high global beta and high confinement, including the highest normalized beta achieved on DIII-D with a quiescent edge.

  20. 40 CFR Appendix B to Part 434 - Baseline Determination and Compliance Monitoring for Pre-existing Discharges at Remining Operations

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Monitoring for Pre-existing Discharges at Remining Operations B Appendix B to Part 434 Protection of... to Part 434—Baseline Determination and Compliance Monitoring for Pre-existing Discharges at Remining... Maximum Daily Limit at subpart C of this part. In the event that a pollutant concentration in the...

  1. Flow regimes in a T-mixer operating with a binary mixture

    NASA Astrophysics Data System (ADS)

    Camarri, Simone; Siconolfi, Lorenzo; Galletti, Chiara; Salvetti, Maria Vittoria

    2015-11-01

    Efficient mixing in small volumes is a key target in many processes. Among the most common micro-devices, passive T-shaped micro-mixers are widely used. For this reason, T-mixers have been studied in the literature and its working flow regimes have been identified. However, in most of the available theoretical studies it is assumed that only one working fluid is used, i.e. that the same fluid at the same thermodynamic conditions is entering the two inlet conduits of the mixer. Conversely, the practical use of micro-devices often involves the mixing of two different fluids or of the same fluid at different thermodynamic conditions. In this case flow regimes significantly different than those observed for a single working fluid may occur. The present work aims at investigating the flow regimes in a T-mixers when water at two different temperatures, i.e. having different viscosity and density, is entering the mixer. The effect of the temperature difference on the flow regimes in a 3D T-mixer is investigated by DNS and stability analysis and the results are compared to the case in which a single working fluid is employed.

  2. SM green fiber laser operating in CW and QCW regimes and producing over 550W of average output power

    NASA Astrophysics Data System (ADS)

    Gapontsev, Valentin; Avdokhin, Alexey; Kadwani, Pankaj; Samartsev, Igor; Platonov, Nikolai; Yagodkin, Roman

    2014-02-01

    We report a single-mode (SM) green laser based on single-pass frequency doubling of a linearly-polarized narrowlinewidth Yb fiber laser in LBO crystal, and configured to operate in a range of regimes from continuous-wave (CW) to high-repetition-rate quasi-continuous-wave (QCW). Adjusting the duty cycle, we maintained high second harmonic generation (SHG) efficiency for various output powers. Average powers of over 550W in QCW and over 350W in CW regimes were obtained with the wall-plug efficiency up to 15%, opening the possibility to creating new class of simple, compact and efficient single-mode green lasers with output power up to 1kW and above. The same approach could also be used to create high-power lasers operating at other wavelengths in ultraviolet and visible spectral ranges.

  3. Hollow cathode operation at high discharge currents. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Friedly, Verlin Joe

    1990-01-01

    It was shown that ion thruster hollow cathode operation at high discharge current levels can induce reduced thruster lifetimes by causing cathode insert overheating and/or erosion of surfaces located downstream of the cathode. The erosion problem has been particularly baffling because the mechanism by which it occurs has not been understood. The experimental investigation described reveals the energies of the ions produced close to the cathode orifice can be several times the anode-to-cathode potential difference generally considered available to accelerate them. These energies (of order 50 eV) are sufficient to cause the observed erosion rates. The effects of discharge current (to 60 A), magnetic field configuration and the cathode flowrate, orifice diameter and insert design on the energies and current densities of these jet ions are examined. A model describing the mechanism by which the high energy ions could be produced when the anode-cathode potential difference is insufficient is proposed. The effects of discharge current on cathode temperature and internal pressure are also examined experimentally and described phenomenologically.

  4. Radiofrequency gas plasma (glow discharge) disinfection of dental operative instruments, including handpieces.

    PubMed

    Baier, R E; Carter, J M; Sorensen, S E; Meyer, A E; McGowan, B D; Kasprzak, S A

    1992-01-01

    The radiofrequency-stimulated argon gas plasma (glow discharge) technique, already well-known for surface cleaning and activation of adhesion, was investigated for determination of its separate potential for rapid disinfection of dental operative instruments. Disinfection effectiveness was judged from diminished post-treatment recovery of viable organisms from the instruments agitated in saline. Streptococcus salivarius, Bacillus stearothermophilus, and Escherichia coli were used as primary contaminant organisms, dried from gelatin-thickened laboratory cultures onto the instruments and not subjected to any preliminary cleaning steps. Significant disinfection was obtained, with no sensible temperature increases, in under 10 minutes in laboratory apparatus consuming fewer than 5 Watts of power per cycle. Also, clinically used and deliberately-saliva-contaminated high-speed handpieces were gas-discharge-treated, with their resultant rapid disinfection noted by complete suppression of the viability of any transferred natural contaminant organisms within two minutes. With regard to preservation of instrument quality, it was also shown that this low-temperature gas-discharge method provides the noted substantial disinfection without deterioration of sharp edges. Work now in progress suggests that the method can provide cool, rapid, and complete sterilization when hydrogen peroxide vapors are present in the gas plasma used for treatment of instruments first given the normally recommended thorough pre-cleaning. PMID:1289559

  5. Porous anodes with helical flow pathways in bioelectrochemical systems: The effects of fluid dynamics and operating regimes

    NASA Astrophysics Data System (ADS)

    Kim, Jung Rae; Boghani, Hitesh C.; Amini, Negar; Aguey-Zinsou, Kondo-François; Michie, Iain; Dinsdale, Richard M.; Guwy, Alan J.; Guo, Zheng Xiao; Premier, Giuliano C.

    2012-09-01

    Bioelectrochemical systems (BES) and/or microbial fuel cell (MFC) mass transport and associated over-potential limitations are affected by flow regimes, which may simultaneously increase the power and pollution treatment capacities. Two electrodes with helical flow channels were compared in the same tubular MFC reactor. 1). A machined monolithic microporous conductive carbon (MMCC). 2). A layered carbon veil with spoked ABS former (LVSF); both presented helical flow channel. Anode performances were compared when subject to temperature, substrate concentration and flow rate variations. The MMCC maximum power increased from 2.9 ± 0.3 to 7.6 ± 0.7 mW with influent acetate concentration, from 1 to 10 mM (with 2 mL min-1), but decreased power to 5.5 ± 0.5 mW at 40 mM, implicated localized pH/buffering. Flow rate (0.1 to 7.5 mL min-1) effects were relatively small but an increase was evident from batch to continuous operation at 0.1 mL min-1. The LVSF configuration showed improved performance in power as the flow rate increased, indicating that flow pattern affects BES performance. Computational fluid dynamics (CFD) modelling showed less uniform flow with the LVSF. Thus flow regime driven mass transfer improves the power output in continuously fed system operation. These results indicate that electrode configuration, flow regime and operating condition need consideration to optimize the bioelectrochemical reaction.

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

    NASA Astrophysics Data System (ADS)

    Reece Roth, J.

    2004-11-01

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

  7. A novel method for the detection of persistent and recurrent climatic regimes as almost invariants of the transfer operator

    NASA Astrophysics Data System (ADS)

    Tantet, A.; Dijkstra, H. A.

    2014-12-01

    A novel method and its numerical implementation to find almost invariants of a dynamical system will be presented, with applications to the detection of persistent and recurrent climatic regimes, coherent structures in ocean flows and spatial patterns of climate variability. The method is based on an estimation of the transfer operator of the particular dynamical system. The detection of almost invariants is posed as a Markov reduction problem with a minimization of the relative entropy, here a measure of the distance between the fine-grained system and the reduced Markov chain. It is implemented using a fast-greedy algorithm from complex network theory. Two applications in different domains of climate science are presented. In the first one, two persistent and recurrent atmospheric flow regimes are identified from a simulation of a barotropic model of the northern hemispheric atmosphere with realistic winter forcing. The regimes correspond to the well-known blocked and zonal circulation regimes of the northern hemisphere. Secondly, the algorithm is applied to a correlation network estimated from 140 years of sea surface temperature data to identify spatial patterns of variability. Dominant patterns on interannual to decadal time-scales are found in the tropical Pacific (El Niño-Southern Oscillation), the North Atlantic (the Atlantic Multidecadal Oscillation) and the Indian ocean and West Pacific.

  8. Design and construction of uniform glow discharge plasma system operating under atmospheric condition

    SciTech Connect

    Kocum, C.; Ayhan, H.

    2007-06-15

    The design of a uniform glow discharge plasma system operating without vacuum is presented. A full-bridge switching circuit was used to switch the transformers. The primary windings of transformers were connected in parallel, but in opposite phase to double the output voltage. Theoretically, 20 000 V{sub pp} was obtained. Rectangle copper electrodes were used, and placed parallel to each other. To prevent the spark production that is, to obtain uniformity, two 2 mm Teflon sheets were glued to the electrodes. However, it was observed that the operating frequency also affected the uniformity. For the system presented here, the frequency at which more uniformity was obtained was found to be 14 kHz.

  9. Integrated scheduling of a container handling system with simultaneous loading and discharging operations

    NASA Astrophysics Data System (ADS)

    Li, Chen; Lu, Zhiqiang; Han, Xiaole; Zhang, Yuejun; Wang, Li

    2016-03-01

    The integrated scheduling of container handling systems aims to optimize the coordination and overall utilization of all handling equipment, so as to minimize the makespan of a given set of container tasks. A modified disjunctive graph is proposed and a mixed 0-1 programming model is formulated. A heuristic algorithm is presented, in which the original problem is divided into two subproblems. In the first subproblem, contiguous bay crane operations are applied to obtain a good quay crane schedule. In the second subproblem, proper internal truck and yard crane schedules are generated to match the given quay crane schedule. Furthermore, a genetic algorithm based on the heuristic algorithm is developed to search for better solutions. The computational results show that the proposed algorithm can efficiently find high-quality solutions. They also indicate the effectiveness of simultaneous loading and discharging operations compared with separate ones.

  10. Ionization coefficients for argon in a micro-discharge

    NASA Astrophysics Data System (ADS)

    Kuschel, Thomas; Stefanović, Ilija; Malović, Gordana; Marić, Dragana; Petrović, Zoran Lj

    2013-08-01

    Ionization coefficients are measured for electrons in a dc micro-discharge in argon from optical emission profiles. The micro-discharge is operated in the Townsend regime between two parallel-plate electrodes. Axial profiles of emission are obtained with sufficient resolution to provide spatial ionization coefficients. The measured coefficients agree very well with the data obtained from other sources, indicating the operation of the discharge in the Townsend regime and also that Townsend mechanisms do not need extension to describe such discharges.

  11. Operational river discharge forecasting in poorly gauged basins: the Kavango River Basin case study

    NASA Astrophysics Data System (ADS)

    Bauer-Gottwein, P.; Jensen, I. H.; Guzinski, R.; Bredtoft, G. K. T.; Hansen, S.; Michailovsky, C. I.

    2014-10-01

    Operational probabilistic forecasts of river discharge are essential for effective water resources management. Many studies have addressed this topic using different approaches ranging from purely statistical black-box approaches to physically-based and distributed modelling schemes employing data assimilation techniques. However, few studies have attempted to develop operational probabilistic forecasting approaches for large and poorly gauged river basins. This study is funded by the European Space Agency under the TIGER-NET project. The objective of TIGER-NET is to develop open-source software tools to support integrated water resources management in Africa and to facilitate the use of satellite earth observation data in water management. We present an operational probabilistic forecasting approach which uses public-domain climate forcing data and a hydrologic-hydrodynamic model which is entirely based on open-source software. Data assimilation techniques are used to inform the forecasts with the latest available observations. Forecasts are produced in real time for lead times of 0 to 7 days. The operational probabilistic forecasts are evaluated using a selection of performance statistics and indicators. The forecasting system delivers competitive forecasts for the Kavango River, which are reliable and sharp. Results indicate that the value of the forecasts is greatest for intermediate lead times between 4 and 7 days.

  12. Operational Constraints on Hydropeaking and its Effects on the Hydrologic and Thermal Regime of a River in Central Chile

    NASA Astrophysics Data System (ADS)

    Olivares, M. A.; Guzman, C.; Rossel, V.; De La Fuente, A.

    2013-12-01

    Hydropower accounts for about 44% of installed capacity in Chile's Central Interconnected System, which serves most of the Chilean population. Hydropower reservoir projects can affect ecosystems by changing the hydrologic regime and water quality. Given its volumen regulation capacity, low operation costs and fast response to demand fluctuations, reservoir hydropower plants commonly operate on a load-following or hydropeaking scheme. This short-term operational pattern produces alterations in the hydrologic regime downstream the reservoir. In the case of thermally stratified reservoirs, peaking operations can affect the thermal structure of the reservoir, as well as the thermal regime downstream. In this study, we assessed the subdaily hydrologic and thermal alteration donwstream of Rapel reservoir in Central Chile for alternative operational scenarios, including a base case and several scenarios involving minimum instream flow (Qmin) and maximum hourly ramping rates (ΔQmax). Scenarios were simulated for the stratification season of summer 2009-2012 in a grid-wide short-term economic dispatch model which prescribes hourly power production by every power plant on a weekly horizon. Power time series are then translated into time series of turbined flows at each hydropower plants. Indicators of subdaily hydrologic alteration (SDHA) were computed for every scenario. Additionally, turbined flows were used as input data for a three-dimensional hydrodynamic model (CWR-ELCOM) of the reservoir which simulated the vertical temperature profile in the reservoir and the outflow temperature. For the time series of outflow temperatures we computed several indicators of subdaily thermal alteration (SDTA). Operational constraints reduce the values of both SDHA and SDTA indicators with respect to the base case. When constraints are applied separately, the indicators of SDHA decrease as each type of constraint (Qmin or ΔQmax) becomes more stringent. However, ramping rate

  13. Operational Regimes in Picosecond and Femtosecond Pulse-Excited Ultrahigh Vacuum SERS.

    PubMed

    Pozzi, Eric A; Gruenke, Natalie L; Chiang, Naihao; Zhdanov, Dmitry V; Jiang, Nan; Seideman, Tamar; Schatz, George C; Hersam, Mark C; Van Duyne, Richard P

    2016-08-01

    We report a systematic study performed in ultrahigh vacuum designed to identify the laser excitation regimes in which plasmonically enhanced ultrashort pulses may be used to nondestructively probe surface-bound molecules. A nondestructive, continuous-wave spectroscopic probe is used to monitor the effects of four different femtosecond- and picosecond-pulsed beams on the SER signals emanating from molecular analytes residing within plasmonically enhanced fields. We identify the roles of plasmonic amplification and alignment with a molecular electronic transition on the observed changes in the SER signals. Our results indicate that overlap of the laser wavelength with the plasmon resonance is the dominant contributor to signal degradation. In addition, signal loss for a given irradiation condition is observed only for molecules residing in hot spots above a threshold enhancement. Identification of suitable laser energy density ranges demonstrates the importance of considering these parameters when implementing SERS in the presence of pulsed irradiation. PMID:27428724

  14. Influence of water barrage operation on changes in hydrological regime of the river below

    NASA Astrophysics Data System (ADS)

    Habel, Michał

    2013-04-01

    At present dams are the cornerstones in the development and management of water resources development of a river basin. The multipurpose dam is a very important project for developing countries, because the population receives domestic and economic benefits from a single investment. But, regardless of the size of the river, its course or climate zone in which it functions, construction of a water barrage constitutes the strongest possible interference in the fluvial system. Development of structures regulating the river course appears to play equally significant role and both these elements cause drastic changes in hydrological phenomena and clastic load transport, which, as a result, may lead to formation of a different channel type. The session is intended to discuss while assessing the influence of the large dam on the water stages regime of the lowland river in particular, how bad technical condition of the dam could affect water management of the river below.

  15. Compatibility of internal transport barrier with steady-state operation in the high bootstrap fraction regime on DIII-D

    NASA Astrophysics Data System (ADS)

    Garofalo, A. M.; Gong, X.; Grierson, B. A.; Ren, Q.; Solomon, W. M.; Strait, E. J.; Van Zeeland, M. A.; Holcomb, C. T.; Meneghini, O.; Smith, S. P.; Staebler, G. M.; Wan, B.; Bravenec, R.; Budny, R. V.; Ding, S.; Hanson, J. M.; Heidbrink, W. W.; Lao, L. L.; Li, G.; Pan, C.; Petty, C. C.; Qian, J.; Paz-Soldan, C.; Xu, G.

    2015-11-01

    Recent EAST/DIII-D joint experiments on the high poloidal beta tokamak regime in DIII-D have demonstrated fully noninductive operation with an internal transport barrier (ITB) at large minor radius, at normalized fusion performance increased by  ⩾30% relative to earlier work (Politzer et al 2005 Nucl. Fusion 45 417). The advancement was enabled by improved understanding of the ‘relaxation oscillations’, previously attributed to repetitive ITB collapses, and of the fast ion behavior in this regime. It was found that the ‘relaxation oscillations’ are coupled core-edge modes amenable to wall-stabilization, and that fast ion losses which previously dictated a large plasma-wall separation to avoid wall over-heating, can be reduced to classical levels with sufficient plasma density. By using optimized waveforms of the plasma-wall separation and plasma density, fully noninductive plasmas have been sustained for long durations with excellent energy confinement quality, bootstrap fraction  ⩾80%, {β\\text{N}}≤slant 4 , {β\\text{P}}≥slant 3 , and {β\\text{T}}≥slant 2% . These results bolster the applicability of the high poloidal beta tokamak regime toward the realization of a steady-state fusion reactor.

  16. Regimes of operation states in passively mode-locked fiber soliton ring laser

    NASA Astrophysics Data System (ADS)

    Gong, Y. D.; Shum, P.; Tang, D. Y.; Lu, C.; Guo, X.; Paulose, V.; Man, W. S.; Tam, H. Y.

    2004-06-01

    The principal of passively mode-locked fiber soliton ring lasers is summarized, including its three output operation states: normal soliton, bound-solitons and noise-like pulse. The experimental results of the passively mode-locked fiber soliton ring lasers developed by us are given. Bound-solitons with different discrete separations and three-bound-solitons state have been observed in our fiber laser for the first time. The relationship among three operation states in fiber soliton laser is analyzed.

  17. Modelling impacts of present and future hydropower operations on flow regimes in data scarce mountain river ecosystems

    NASA Astrophysics Data System (ADS)

    Geris, Josie; Tetzlaff, Doerthe; Seibert, Jan; Vis, Marc; Soulsby, Chris

    2014-05-01

    characterise the natural flow regime, assess the regulation impacts, and explore sensitivities to hydrological changes in water management. Overall, changes following regulation in the Lyon include decreases in inter-and intra-annual variability of all aspects of the flow regime that are important in various life stages of the Atlantic Salmon. Sensitivity tests showed that a more variable release regime, as opposed to changes in the efficiency of the present regulation regime, could be most beneficial for the ecological status of the Lyon, while still maintaining viable hydropower generation. The results demonstrated that the simple, conceptual modelling approach developed here can capture the dominant catchment and regulation processes well, especially at the time scale at which operation rules apply. Consequentially, the approach is data undemanding, flexible, and providing a basis for assessing impacts on flow regimes and informing environmental flows in other (data sparse) regions with heavily regulated mountain river ecosystems. Furthermore, its results are easily communicated to stakeholders, providing a basis for discussing the development of new adaptive management strategies.

  18. High energy bursts from a solid state laser operated in the heat capacity limited regime

    SciTech Connect

    Albrecht, G.; George, E.V.; Krupke, W.

    1994-12-31

    Solid state laser technology is a very well developed field and numerous embodiments and modes of operation have been demonstrated. A more recent development has been the pumping of a solid state laser active medium with an array of diode lasers (diode pumping, for short). These diode pump packages have previously been developed to pump solid state lasers with good efficiency, but low average power. This invention is a method and the resulting apparatus for operating a solid state laser in the heat capacity mode. Instead of cooling the laser, the active medium will heat up until it reaches some maximum acceptable temperature. The waste heat is stored in the active medium itself.

  19. Towards multi-sensor operational monitoring of the European fire regime

    NASA Astrophysics Data System (ADS)

    Beck, P. S. A.; San Miguel-Ayanz, J.; Busetto, L.; Boca, R.; Boccacci, F.

    2014-12-01

    Europe loses approximately half a million hectares of forest to human-caused fires annually. High population densities and fuel loads in areas of forest recovery aid uncontrolled wildfires, despite decreasing use of fire in agriculture. In rural areas such as the Mediterranean, pervasive wildfires can be indicative of socio-economic decline and themselves cause political tension. Since the 2000s, the European Forest Fires Information System maps forest fires in Europe daily, as part of a modular system that also assesses fire risk. This system, developed and maintained by the European Commission, feeds pan-European information to forest fire and civil protection agencies in the EU and provides a consistent quality-checked forest fire record for scientific analysis and global reporting initiatives. The current fire mapping algorithm captures fires larger than 50 ha, owing to its reliance on MODIS imagery. As a result, the system misses about 95% of Europe's forest fires, which contribute 20-25% of the annually burned area, because they are too small for detection. We present a new approach to fire mapping that relies on multiple satellite sensors to improve spatiotemporal detail of mapped fire activity. We implemented the approach to map European wildfires exploiting the 30 m spatial resolution of the Landsat 8 sensor, and the daily overpass of the MODIS sensors. By doing so, detections of smaller fires improved dramatically, although they were somewhat delayed. The algorithm relies on a set of heuristic rules that translate knowledge of the temporal dynamics of fire disturbance, recovery, and confounding factors such as agricultural harvest, into spectro-temporal criteria. By design, it can be adapted to areas with different fire regimes, and ingest information from additional satellite sensors to further improve detection rates and times. We discuss the latter in the context of the Sentinel missions, and their potential contribution to global wildfire monitoring.

  20. Soft X-Ray Emission Analysis Of A Pulsed Capillary Discharge Operated In Nitrogen

    NASA Astrophysics Data System (ADS)

    Valdivia, M. P.; Valenzuela, J. C.; Wyndham, E. S.; Favre, M.; Chuaqui, H.; Bhuyan, H.

    2014-05-01

    We present results from a pulsed capillary ns discharge source, operated in Nitrogen and N/He mixtures, in an alumina capillary 2.1mm long with outer diameter of 6.3mm and inner diameter of 1.6mm. The electrical energy stored is 0.5J with peak current of 6kA. Fast charging from an IGBT based pulsed power circuit allows operation at 35-600 Hz with voltages in the range of 18-24kV. Characteristic time-integrated N/He spectra were recorded and analyzed for values of 20-200 Å, with clear evidence of He-like Nitrogen emission at 28.8Å, which represents a possible source for water window soft x-ray microscopy. Filtered diode measurements reveal the influence of axial electron beams, generated by hollow cathode dynamics, on the x-ray emission in the range of 300-450 eV. We discuss optimal voltage applied and pressure conditions for soft x-ray generation. Time-integrated MCP images of a filtered slit-wire system delivered clear evidence of full wall detachment with ~500μm in radial size for the entire emission range and ~200μm for the emission in the 300-450 eV range.

  1. Operation of a full-scale pumped flow biofilm reactor (PFBR) under two aeration regimes.

    PubMed

    O'Reilly, E; Rodgers, M; Clifford, E

    2011-01-01

    A novel technology suitable for centralised and decentralised wastewater treatment has been developed, extensively tested at laboratory-scale, and trialled at a number of sites for populations ranging from 15 to 400 population equivalents (PE). The two-reactor-tank pumped flow biofilm reactor (PFBR) is characterised by: (i) its simple construction; (ii) its ease of operation and maintenance; (iii) low operating costs; (iv) low sludge production; and (v) comprising no moving parts or compressors, other than hydraulic pumps. By operating the system in a sequencing batch biofilm reactor (SBBR) mode, the following treatment can be achieved: 5-day biochemical oxygen demand (BOD5), chemical oxygen demand (COD) and total suspended solids (TSS) reduction; nitrification and denitrification. During a 100-day full-scale plant study treating municipal wastewater and operating at 165 PE and 200 PE (Experiments 1 and 2, respectively), maximum average removals of 94% BOD5, 86% TSS and 80% ammonium-nitrogen (NH4-N) were achieved. During the latter part of Experiment 2, effluent concentrations averaged: 14 mg BOD5/l; 32 mg COD(filtered)/l; 14 mg TSS/l; 4.4 mg NH4-N/l; and 4.0 mg NO3-N/l (nitrate-nitrogen). The average energy consumption was 0.46-0.63 kWh/m3(treated) or 1.25-1.76 kWh/kg BOD5 removed. No maintenance was required during these experiments. The PFBR technology offers a low energy, minimal maintenance technology for the treatment of municipal wastewater. PMID:22214073

  2. A planar diode operating in the regime of limited electron emission

    NASA Astrophysics Data System (ADS)

    Pushkarev, A. I.; Sazonov, R. V.

    2008-04-01

    The current-voltage characteristic of a planar diode with a graphite explosive-emission cathode has been experimentally studied at the initial stage of electron current formation. An analytical expression has been obtained for the total area of discrete emitting centers in the cellular structure approximation, assuming that the number of such emitting centers operative during the current pulse formation is constant. It is shown that the electron current buildup for a cathode surface with discrete emitting centers is satisfactorily described by a modified Child-Langmuir formula with the form factor decreasing from F = 6 to 1.

  3. Wind tunnel results of advanced high speed propellers in the takeoff, climb, and landing operating regimes

    NASA Technical Reports Server (NTRS)

    Stefko, G. L.; Jeracki, R. J.

    1985-01-01

    Low speed wind tunnel performance tests of two advanced propellers were completed. The 62.2 cm diameter adjustable pitch models were tested at Mach numbers typical of takeoff, initial climbout, and landing speeds in the 10 by 10 ft Supersonic Wind Tunnel. Both models had eight blades and a cruise design point operating condition of 0.80 Mach number, 10.668 km S.A. altitude, 243.8 m/s tip speed and a high power loading of 301 kW sq m. No adverse or unusual low speed operating conditions were found during the test with either the straight blade SR-2 or the 45 deg swept SR-3 propellers. The 45 deg swept propeller efficiency exceeded the straight blade efficiency by 4 to 5 percent. Typical net efficiencies of the straight and 45 deg swept propeller at a Mach 0.20 takeoff condition were 50.2 and 54.9 percent respectively. At a Mach 0.34 climb condition, the efficiencies were 53.7 and 59.1 percent. Reverse thrust data indicates that these propellers are capable of producing more reverse thrust at Mach 0.20 than a high bypass turbofan engine at Mach 0.20.

  4. Wind tunnel results of advanced high speed propellers in the takeoff, climb and landing operating regimes

    NASA Technical Reports Server (NTRS)

    Stefko, G. L.; Jeracki, R. J.

    1985-01-01

    Low speed wind tunnel performance tests of two advanced propellers were completed. The 62.2 cm diameter adjustable pitch models were tested at Mach numbers typical of takeoff, initial climbout, and landing speeds in the 10 by 10 ft Supersonic Wind Tunnel. Both models had eight blades and a cruise design point operating condition of 0.80 Mach number, 10.668 km S.A. altitude, 243.8 m/s tip speed and a high power loading of 301 kW sq m. No adverse or unusual low speed operating conditions were found during the test with either the straight blade SR-2 or the 45 deg swept SR-3 propellers. The 45 deg swept propeller efficiency exceeded the straight blade efficiency by 4 to 5%. Typical net efficiencies of the straight and 45 deg swept propeller at a Mach 0.20 takeoff condition were 50.2 and 54.9% respectively. At a Mach 0.34 climb condition, the efficiencies were 53.7 and 59.1%. Reverse thrust data indicates that these propellers are capable of producing more reverse thrust at Mach 0.20 than a high bypass turbofan engine at Mach 0.20.

  5. Restoring a flow regime through the coordinated operation of a multireservoir system: The case of the Zambezi River basin

    NASA Astrophysics Data System (ADS)

    Tilmant, A.; Beevers, L.; Muyunda, B.

    2010-07-01

    Large storage facilities in hydropower-dominated river basins have traditionally been designed and managed to maximize revenues from energy generation. In an attempt to mitigate the externalities downstream due to a reduction in flow fluctuation, minimum flow requirements have been imposed to reservoir operators. However, it is now recognized that a varying flow regime including flow pulses provides the best conditions for many aquatic ecosystems. This paper presents a methodology to derive a trade-off relationship between hydropower generation and ecological preservation in a system with multiple reservoirs and stochastic inflows. Instead of imposing minimum flow requirements, the method brings more flexibility to the allocation process by building upon environmental valuation studies to derive simple demand curves for environmental goods and services, which are then used in a reservoir optimization model together with the demand for energy. The objective here is not to put precise monetary values on environmental flows but to see the marginal changes in release policies should those values be considered. After selecting appropriate risk indicators for hydropower generation and ecological preservation, the trade-off curve provides a concise way of exploring the extent to which one of the objectives must be sacrificed in order to achieve more of the other. The methodology is illustrated with the Zambezi River basin where large man-made reservoirs have disrupted the hydrological regime.

  6. Inverse model construction for control implementation of macro fiber composite actuators operating in hysteretic regimes

    NASA Astrophysics Data System (ADS)

    Stuebner, Michael; Smith, Ralph C.

    2010-04-01

    Macro Fiber Composite (MFC) actuators utilize PZT fibers embedded in an epoxy matrix for structural actuation. Due to their construction, they are lightweight and provide broadband inputs. Significant advantages of MFC actuators are their high performance, durability, and flexibility when compared to traditional piezoceramic actuators. They are presently being considered for a range of applications including positioning of membrane mirrors and structural control in the aerospace and automotive industry. However, they exhibit varying degrees of hysteresis and constitutive nonlinearities throughout their operating range that must be incorporated in models to achieve the full capabilities of the materials. In this paper, hysteresis is modeled using the homogenized energy model. The inverse model is then used to construct an inverse compensator framework suitable for subsequent control design. The performance of the inverse compensator is illustrated through a numerical example.

  7. Integrated Operating Scenario to Achieve 100-Second, High Electron Temperature Discharge on EAST

    NASA Astrophysics Data System (ADS)

    Qian, Jinping; Gong, Xianzu; Wan, Baonian; Liu, Fukun; Wang, Mao; Xu, Handong; Hu, Chundong; Wang, Liang; Li, Erzhong; Zeng, Long; Ti, Ang; Shen, Biao; Lin, Shiyao; Shao, Linming; Zang, Qing; Liu, Haiqing; Zhang, Bin; Sun, Youwen; Xu, Guosheng; Liang, Yunfeng; Xiao, Bingjia; Hu, Liqun; Li, Jiangang; EAST Team

    2016-05-01

    Stationary long pulse plasma of high electron temperature was produced on EAST for the first time through an integrated control of plasma shape, divertor heat flux, particle exhaust, wall conditioning, impurity management, and the coupling of multiple heating and current drive power. A discharge with a lower single null divertor configuration was maintained for 103 s at a plasma current of 0.4 MA, q95 ≈7.0, a peak electron temperature of >4.5 keV, and a central density ne(0)∼2.5×1019 m‑3. The plasma current was nearly non-inductive (Vloop <0.05 V, poloidal beta ∼ 0.9) driven by a combination of 0.6 MW lower hybrid wave at 2.45 GHz, 1.4 MW lower hybrid wave at 4.6 GHz, 0.5 MW electron cyclotron heating at 140 GHz, and 0.4 MW modulated neutral deuterium beam injected at 60 kV. This progress demonstrated strong synergy of electron cyclotron and lower hybrid electron heating, current drive, and energy confinement of stationary plasma on EAST. It further introduced an example of integrated “hybrid” operating scenario of interest to ITER and CFETR. supported by the National Magnetic Confinement Fusion Science Foundation of China (Nos. 2015GB102000 and 2014GB103000)

  8. 33 CFR 151.66 - Operating requirements: Discharge of garbage in the Great Lakes and other navigable waters.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION VESSELS CARRYING OIL... Pollution from Ships Garbage Pollution and Sewage § 151.66 Operating requirements: Discharge of garbage in... a 6 mile radius from Stannard Rock Light, at 47°10′57″ N 87°13′34″ W; Superior Shoal Protection...

  9. 33 CFR 151.66 - Operating requirements: Discharge of garbage in the Great Lakes and other navigable waters.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION VESSELS CARRYING OIL... Pollution from Ships Garbage Pollution and Sewage § 151.66 Operating requirements: Discharge of garbage in... a 6 mile radius from Stannard Rock Light, at 47°10′57″ N 87°13′34″ W; Superior Shoal Protection...

  10. 33 CFR 151.66 - Operating requirements: Discharge of garbage in the Great Lakes and other navigable waters.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION VESSELS CARRYING OIL... Pollution from Ships Garbage Pollution and Sewage § 151.66 Operating requirements: Discharge of garbage in... a 6 mile radius from Stannard Rock Light, at 47°10′57″ N 87°13′34″ W; Superior Shoal Protection...

  11. 33 CFR 151.66 - Operating requirements: Discharge of garbage in the Great Lakes and other navigable waters.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Operating requirements: Discharge of garbage in the Great Lakes and other navigable waters. 151.66 Section 151.66 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION VESSELS CARRYING OIL, NOXIOUS LIQUID SUBSTANCES, GARBAGE, MUNICIPAL...

  12. 40 CFR Appendix B to Part 434 - Baseline Determination and Compliance Monitoring for Pre-existing Discharges at Remining Operations

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 29 2010-07-01 2010-07-01 false Baseline Determination and Compliance Monitoring for Pre-existing Discharges at Remining Operations B Appendix B to Part 434 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS COAL MINING...

  13. 40 CFR Appendix B to Part 434 - Baseline Determination and Compliance Monitoring for Pre-existing Discharges at Remining Operations

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Monitoring for Pre-existing Discharges at Remining Operations B Appendix B to Part 434 Protection of.... B Appendix B to Part 434—Baseline Determination and Compliance Monitoring for Pre-existing... per year. d. Accommodating Data Below the Maximum Daily Limit at subpart C of this part. In the...

  14. 40 CFR Appendix B to Part 434 - Baseline Determination and Compliance Monitoring for Pre-existing Discharges at Remining Operations

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Monitoring for Pre-existing Discharges at Remining Operations B Appendix B to Part 434 Protection of.... B Appendix B to Part 434—Baseline Determination and Compliance Monitoring for Pre-existing... per year. d. Accommodating Data Below the Maximum Daily Limit at subpart C of this part. In the...

  15. 40 CFR Appendix B to Part 434 - Baseline Determination and Compliance Monitoring for Pre-existing Discharges at Remining Operations

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Monitoring for Pre-existing Discharges at Remining Operations B Appendix B to Part 434 Protection of.... B Appendix B to Part 434—Baseline Determination and Compliance Monitoring for Pre-existing... per year. d. Accommodating Data Below the Maximum Daily Limit at subpart C of this part. In the...

  16. Benthic foraminiferal responses to operational drill cutting discharge in the SW Barents Sea - a case study.

    NASA Astrophysics Data System (ADS)

    Aagaard-Sørensen, Steffen; Junttila, Juho; Dijkstra, Noortje

    2016-04-01

    Petroleum related exploration activities started in the Barents Sea 1980, reaching 97 exploration wells drilled per January 2013. The biggest operational discharge from drilling operations in the Barents Sea is the release of drill cuttings (crushed seabed and/or bedrock) and water based drilling muds including the commonly used weighing material barite (BaSO4). Barium (Ba), a constituent of barite, does not degrade and can be used to evaluate dispersion and accumulation of drill waste. The environmental impact associated with exploration drilling within the Goliat Field, SW Barents Sea in 2006 was evaluated via a multiproxy investigation of local sediments. The sediments were retrieved in November 2014 at ~350 meters water depth and coring sites were selected at distances of 5, 30, 60, 125 and 250 meters from the drill hole in the eastward downstream direction. The dispersion pattern of drill waste was estimated via measurements of sediment parameters including grain size distribution and water content in addition to heavy metal and total organic carbon contents. The environmental impact was evaluated via micro faunal analysis based on benthic foraminiferal (marine shell bearing protists) fauna composition and concentration changes. Observing the sediment parameters, most notably Ba levels, reveals that dispersion of drill waste was limited to <125 meters from the drill site with drill waste thicknesses decreasing downstream. The abruptness and quantity of drill waste sedimentation initially smothered the foraminiferal fauna at ≤ 30 meters from the drill site, while at a distance of 60 meters, the fauna seemingly survived and bioturbation persisted. Analysis of the live (Nov 2014) foraminiferal fauna reveals a natural species composition at all distances from the drill site within the top sediments (0-5 cm core depth). Furthermore, the fossil foraminiferal fauna composition found within post-impacted top sediment sections, particularly in the cores situated at

  17. Advances in X-Band TW Accelerator Structures Operating in the 100 MV/M Regime

    SciTech Connect

    Higo, Toshiyasu; Higashi, Yasuo; Matsumoto, Shuji; Yokoyama, Kazue; Adolphsen, Chris; Dolgashev, Valery; Jensen, Aaron; Laurent, Lisa; Tantawi, Sami; Wang, Faya; Wang, Juwen; Dobert, Steffen; Grudiev, Alexej; Riddone, Germana; Wuensch, Walter; Zennaro, Riccardo; /CERN

    2012-07-05

    A CERN-SLAC-KEK collaboration on high gradient X-band accelerator structure development for CLIC has been ongoing for three years. The major outcome has been the demonstration of stable 100 MV/m gradient operation of a number of CLIC prototype structures. These structures were fabricated using the technology developed from 1994 to 2004 for the GLC/NLC linear collider initiative. One of the goals has been to refine the essential parameters and fabrication procedures needed to realize such a high gradient routinely. Another goal has been to develop structures with stronger dipole mode damping than those for GLC/NLC. The latter requires that the surface temperature rise during the pulse be higher, which may increase the breakdown rate. One structure with heavy damping has been RF processed and another is nearly finished. The breakdown rates of these structures were found to be higher by two orders of magnitude compared to those with equivalent acceleration mode parameters but without the damping features. This paper presents these results together with some of the earlier results from non-damped structures.

  18. Simple contour analysis of ignition conditions and plasma operating regimes in tokamaks

    SciTech Connect

    Uckan, N.A.; Sheffield, J.; Selcow, E.C.

    1985-01-01

    Contour plots of ignition, auxiliary power requirements, heating and operating windows, optimal path to ignition, ignition margin, etc., are generated analytically in terms of a small number of parameters (aB/sub 0//sup 2//q/sub */, R/sub 0//B/sub 0/, , etc.) for classes of devices with equivalent performance. Numerical studies are carried out to map the physics design space. Considering both the Murakami density limit (approx.B/sub 0//R/sub 0/) and the Troyon beta limit (approx.I/aB/sub 0/), results from analytic calculations indicate that in a standard tokamak geometry (A approx. 2.5 to 3.5, kappa = b/a approx. 1.6 to 1.7, q/sub psi/ approx. 2.6) devices with aB/sub 0//sup 2//q/sub */ approx. 20 should be ignitable provided confinement does not degrade with heating (ohmic + alpha + auxiliary, etc.) power; however, aB/sub 0//sup 2//q/sub */ approx. 30 (25) may be required for minimal ignition for a typical L- (H-) mode confinement scaling. Increased plasma elongation (kappa approx. 2) may help to reduce these requirements.

  19. Femtosecond Laser Tagging Characterization of a Sweeping Jet Actuator Operating in the Compressible Regime

    NASA Technical Reports Server (NTRS)

    Peters, Christopher J.; Miles, Richard B.; Burns, Ross A.; Bathel, Brett F.; Jones, Gregory S.; Danehy, Paul M.

    2016-01-01

    A sweeping jet (SWJ) actuator operating over a range of nozzle pressure ratios (NPRs) was characterized with femtosecond laser electronic excitation tagging (FLEET), single hot-wire anemometry (HWA) and high-speed/phase-averaged schlieren. FLEET velocimetry was successfully demonstrated in a highly unsteady, oscillatory flow containing subsonic through supersonic velocities. Qualitative comparisons between FLEET and HWA (which measured mass flux since the flow was compressible) showed relatively good agreement in the external flow profiles. The spreading rate was found to vary from 0.5 to 1.2 depending on the pressure ratio. The precision of FLEET velocity measurements in the external flow field was poorer (is approximately equal to 25 m/s) than reported in a previous study due to the use of relatively low laser fluences, impacting the velocity fluctuation measurements. FLEET enabled velocity measurements inside the device and showed that choking likely occurred for NPR = 2.0, and no internal shockwaves were present. Qualitative oxygen concentration measurements using FLEET were explored in an effort to gauge the jet's mixing with the ambient. The jet was shown to mix well within roughly four throat diameters and mix fully within roughly eight throat diameters. Schlieren provided visualization of the internal and external flow fields and showed that the qualitative structure of the internal flow does not vary with pressure ratio and the sweeping mechanism observed for incompressible NPRs also probably holds for compressible NPRs.

  20. Operating Regime for a Backward Raman Laser Amplifier in Preformed Plasma

    SciTech Connect

    Daniel S. Clark; Nathaniel J. Fisch

    2003-02-06

    A critical issue in the generation of ultra-intense, ultra-short laser pulses by backward Raman scattering in plasma is the stability of the pumping pulse to premature backscatter from thermal fluctuations in the preformed plasma. Malkin et al. [V.M. Malkin, et al., Phys. Rev. Lett. 84 (6):1208-1211, 2000] demonstrated that density gradients may be used to detune the Raman resonance in such a way that backscatter of the pump from thermal noise can be stabilized while useful Raman amplification persists. Here plasma conditions for which the pump is stable to thermal Raman backscatter in a homogeneous plasma and the density gradients necessary to stabilize the pump for other plasma conditions are quantified. Other ancillary constraints on a Raman amplifier are also considered to determine a specific region in the Te-he plane where Raman amplification is feasible. By determining an operability region, the degree of uncertainty in density or temperature tolerable for an experimental Raman amplifier is thus also identified. The fluid code F3D, which includes the effects of thermal fluctuations, is used to verify these analytic estimates.

  1. Multi-GeV electron beams from capillary discharge guided sub-petawatt class laser pulses in the self-trapping regime

    NASA Astrophysics Data System (ADS)

    Leemans, Wim

    2014-10-01

    Laser plasma accelerators (LPAs) can produce acceleration gradients on the order of tens to hundreds of GV/m, making them attractive as compact particle accelerators. During the past decade, quasi-monochromatic electron beams at the 1 GeV energy level have been produced using laser pulses at the 40-50 TW peak power level. With the availability of petawatt class lasers, beams up to 2 GeV have been produced from 7 cm long gas cells at UT Austin using 150 J laser pulses and at the 1 GeV level with tails extending to 3 GeV at the GIST facility in Korea. In this talk we present experimental results using the 1 Hz petawatt class BELLA laser at LBNL of the generation of multi-GeV electron beams with center energy up to 4.2 GeV, 6% rms energy spread, charge approximately 10 pC and an rms divergence around 0.3 mrad. The beams were produced from 9 cm long capillary discharge waveguide structure with a plasma density of ~ 7 ×1017cm-3 , powered by laser pulses with peak power up to 0.3 PW. Preformed plasma waveguides allow the use of lower laser power compared to unguided plasma structures to achieve the same beam energy. Detailed comparison between experiment and simulation indicates the importance of the near-field laser transverse mode quality on guiding and acceleration in the LPA. By tuning the plasma density, regimes were found where laser beams with a top hat near-field profile were guided well, and where high energy electron beams can be produced, with narrow divergence [ <0.8 mrad (FWHM)], and relatively small integrated energy spread (<10%). Provided that the slice energy spread and emittance are sufficiently low, electron beams with this energy could power x-ray free electron lasers. Future experiments will aim at increasing the beam energy to the 10 GeV level. Work supported by Office of Science, Office of HEP, US DOE Contract DE-AC02-05CH11231.

  2. Operation Characteristics of Dielectric Barrier Discharge for Ignition Enhancement in Supersonic Flow

    NASA Astrophysics Data System (ADS)

    Matsubara, Yoshinori; Okazaki, Megumu; Yamamoto, Takamasa; Takita, Kenichi

    The authors developed a method to produce nonequilibrium plasma by dielectric barrier discharge (DBD) in supersonic flow and investigated the possibility for using it as an ignition enhancement technique in a high speed engine, such as a scramjet engine. The discharge characteristics were investigated by varying applied voltage and the flow Mach number. It was revealed from direct photographs that the discharges got stronger and the volume got larger as flow Mach number increased. Estimated discharge power indicated that nonequilibrium plasma could be generated by considerably small energy in comparison with thermal plasma such as a plasma jet torch, which is a typical thermal plasma. The emissions from several excited molecules and atoms were confirmed by spectroscopic measurement of the plasma. Ignition delay analysis revealed that the effect of ozone (O3) addition to shorten the ignition delay time of mixture is almost equal to those of O or H radicals.

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

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

    SciTech Connect

    Sun Wenting; Li Guo; Li Heping; Bao Chengyu; Wang Huabo; Zeng Shi; Gao Xing; Luo Huiying

    2007-06-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2007-06-01

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

  6. Extension of operation regimes and investigation of three-dimensional currentless plasmas in the Large Helical Device

    NASA Astrophysics Data System (ADS)

    Kaneko, O.; Yamada, H.; Inagaki, S.; Jakubowski, M.; Kajita, S.; Kitajima, S.; Kobayashi; Koga, K.; Morisaki, T.; Morita, S.; Mutoh, T.; Sakakibara, S.; Suzuki, Y.; Takahashi, H.; Tanaka, K.; Toi, K.; Yoshimura, Y.; Akiyama, T.; Asahi, Y.; Ashikawa, N.; Chikaraishi, H.; Cooper, A.; Darrow, D. S.; Drapiko, E.; Drewelow, P.; Du, X.; Ejiri, A.; Emoto, M.; Evans, T.; Ezumi, N.; Fujii, K.; Fukuda, T.; Funaba, H.; Furukawa, M.; Gates, D. A.; Goto, M.; Goto, T.; Guttenfelder, W.; Hamaguchi, S.; Hasuo, M.; Hino, T.; Hirooka, Y.; Ichiguchi, K.; Ida, K.; Idei, H.; Ido, T.; Igami, H.; Ikeda, K.; Imagawa, S.; Imai, T.; Isobe, M.; Itagaki, M.; Ito, T.; Itoh, K.; Itoh, S.; Iwamoto, A.; Kamiya, K.; Kariya, T.; Kasahara, H.; Kasuya, N.; Kato, D.; Kato, T.; Kawahata, K.; Koike, F.; Kubo, S.; Kumazawa, R.; Kuwahara, D.; Lazerson, S.; Lee, H.; Masuzaki, S.; Matsuoka, S.; Matsuura, H.; Matsuyama, A.; Michael, C.; Mikkelsen, D.; Mitarai, O.; Mito, T.; Miyazawa, J.; Motojima, G.; Mukai, K.; Murakami, A.; Murakami, I.; Murakami, S.; Muroga, T.; Muto, S.; Nagaoka, K.; Nagasaki, K.; Nagayama, Y.; Nakajima, N.; Nakamura, H.; Nakamura, Y.; Nakanishi, H.; Nakano, H.; Nakano, T.; Narihara, K.; Narushima, Y.; Nishimura, K.; Nishimura, S.; Nishiura, M.; Nunami, Y. M.; Obana, T.; Ogawa, K.; Ohdachi, S.; Ohno, N.; Ohyabu, N.; Oishi, T.; Okamoto, M.; Okamoto, A.; Osakabe, M.; Oya, Y.; Ozaki, T.; Pablant, N.; Peterson, B. J.; Sagara, A.; Saito, K.; Sakamoto, R.; Sakaue, H.; Sasao, M.; Sato, K.; Sato, M.; Sawada, K.; Seki, R.; Seki, T.; Sergeev, V.; Sharapov, S.; Sharov, I.; Shimizu, A.; Shimozuma, T.; Shiratani, M.; Shoji, M.; Sudo, S.; Sugama, H.; Suzuki, C.; Takahata, K.; Takeiri, Y.; Takemura, Y.; Takeuchi, M.; Tamura, H.; Tamura, N.; Tanaka, H.; Tanaka, T.; Tingfeng, M.; Todo, Y.; Tokitani, M.; Tokunaga, K.; Tokuzawa, T.; Tsuchiya, H.; Tsumori, K.; Ueda, Y.; Vyacheslavov, L.; Watanabe, K. Y.; Watanabe, T.; Watanabe, T. H.; Wieland, B.; Yamada, I.; Yamada, S.; Yamamoto, S.; Yanagi, N.; Yasuhara, R.; Yokoyama, M.; Yoshida, N.; Yoshimura, S.; Yoshinaga, T.; Yoshinuma, M.; Komori, A.

    2013-10-01

    The progress of physical understanding as well as parameter improvement of net-current-free helical plasma is reported for the Large Helical Device since the last Fusion Energy Conference in Daejeon in 2010. The second low-energy neutral beam line was installed, and the central ion temperature has exceeded 7 keV, which was obtained by carbon pellet injection. Transport analysis of the high-Ti plasmas shows that the ion-thermal conductivity and viscosity decreased after the pellet injection although the improvement does not last long. The effort has been focused on the optimization of plasma edge conditions to extend the operation regime towards higher ion temperature and more stable high density and high beta. For this purpose a portion of the open helical divertors are being modified to the baffle-structured closed ones aimed at active control of the edge plasma. It is compared with the open case that the neutral pressure in the closed helical divertor increased by ten times as predicted by modelling. Studies of physics in a three-dimensional geometry are highlighted in the topics related to the response to a resonant magnetic perturbation at the plasma periphery such as edge-localized-mode mitigation and divertor detachment. Novel approaches of non-local and non-diffusive transport have also been advanced.

  7. Role of interactions in an electronic Fabry–Perot interferometer operating in the quantum Hall effect regime

    PubMed Central

    Ofek, Nissim; Bid, Aveek; Heiblum, Moty; Stern, Ady; Umansky, Vladimir; Mahalu, Diana

    2010-01-01

    Interference of edge channels is expected to be a prominent tool for studying statistics of charged quasiparticles in the quantum Hall effect (QHE). We present here a detailed study of an electronic Fabry–Perot interferometer (FPI) operating in the QHE regime [C. Chamon, et al. (1997) Phys Rev B 55:2331–2334], with the phase of the interfering quasiparticles controlled by the Aharonov–Bohm effect. Our main finding is that Coulomb interactions among the electrons dominate the interference, even in a relatively large area FPI, leading to a strong dependence of the area enclosed by the interference loop on the magnetic field. In particular, for a composite edge structure, with a few independent edge channels propagating along the edge, interference of the outmost edge channel (belonging to the lowest Landau level) was insensitive to magnetic field—suggesting a constant enclosed flux. However, when any of the inner edge channels interfered, the enclosed flux decreased when the magnetic field increased. By intentionally varying the enclosed area with a biased metallic gate and observing the periodicity of the interference pattern, charges e (for integer filling factors) and e/3 (for a fractional filling factor) were found to be expelled from the FPI. Moreover, these observations provided also a novel way of detecting the charge of the interfering quasiparticles. PMID:20212147

  8. Operating modes of a hydrogen ion source based on a hollow-cathode pulsed Penning discharge

    NASA Astrophysics Data System (ADS)

    Oks, E. M.; Shandrikov, M. V.; Vizir, A. V.

    2016-02-01

    An ion source based on a hollow-cathode Penning discharge was switched to a high-current pulsed mode (tens of amperes and tens of microseconds) to produce an intense hydrogen ion beam. With molecular hydrogen (H2), the ion beam contained three species: H+, H2+, and H3+. For all experimental conditions, the fraction of H2+ ions in the beam was about 10 ÷ 15% of the total ion beam current and varied little with ion source parameters. At the same time, the ratio of H+ and H3+ depended strongly on the discharge current, particularly on its distribution in the gap between the hollow and planar cathodes. Increasing the discharge current increased the H+ fraction in ion beam. The maximum fraction of H+ reached 80% of the total ion beam current. Forced redistribution of the discharge current in the cathode gap for increasing the hollow cathode current could greatly increase the H3+ fraction in the beam. At optimum parameters, the fraction of H3+ ions reached 60% of the total ion beam current.

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

    SciTech Connect

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

    2015-11-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  11. 76 FR 78599 - National Pollutant Discharge Elimination System (NPDES) Concentrated Animal Feeding Operation...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-19

    ..., 2011 (76 FR 65431) (FRL-9481-7) EPA published a proposed rule entitled, National Pollutant Discharge.... Copies of the proposal are available on EPA's Web site at http://www.epa.gov/npdes/regulations/cafo_fr...-54,999........ Less than 16,500. Laying hens or broilers (liquid 30,000 or more..........

  12. Ozone generation in a kHz-pulsed He-O2 capillary dielectric barrier discharge operated in ambient air

    NASA Astrophysics Data System (ADS)

    Sands, Brian L.; Ganguly, Biswa N.

    2013-12-01

    The generation of reactive oxygen species using nonequilibrium atmospheric pressure plasma jet devices has been a subject of recent interest due to their ability to generate localized concentrations from a compact source. To date, such studies with plasma jet devices have primarily utilized radio-frequency excitation. In this work, we characterize ozone generation in a kHz-pulsed capillary dielectric barrier discharge configuration comprised of an active discharge plasma jet operating in ambient air that is externally grounded. The plasma jet flow gas was composed of helium with an admixture of up to 5% oxygen. A unipolar voltage pulse train with a 20 ns pulse risetime was used to drive the discharge at repetition rates between 2-25 kHz. Using UVLED absorption spectroscopy centered at 255 nm near the Hartley-band absorption peak, ozone was detected over 1 cm from the capillary axis. We observed roughly linear scaling of ozone production with increasing pulse repetition rate up to a "turnover frequency," beyond which ozone production steadily dropped and discharge current and 777 nm O(5P→5S°) emission sharply increased. The turnover in ozone production occurred at higher pulse frequencies with increasing flow rate and decreasing applied voltage with a common energy density of 55 mJ/cm3 supplied to the discharge. The limiting energy density and peak ozone production both increased with increasing O2 admixture. The power dissipated in the discharge was obtained from circuit current and voltage measurements using a modified parallel plate dielectric barrier discharge circuit model and the volume-averaged ozone concentration was derived from a 2D ozone absorption measurement. From these measurements, the volume-averaged efficiency of ozone production was calculated to be 23 g/kWh at conditions for peak ozone production of 41 mg/h at 11 kV applied voltage, 3% O2, 2 l/min flow rate, and 13 kHz pulse repetition rate, with 1.79 W dissipated in the discharge.

  13. Mass spectrometric investigation of the ionic species in a dielectric barrier discharge operating in helium-water vapour mixtures

    NASA Astrophysics Data System (ADS)

    Abd-Allah, Z.; Sawtell, D. A. G.; McKay, K.; West, G. T.; Kelly, P. J.; Bradley, J. W.

    2015-03-01

    Using advanced mass spectrometry the chemistry of ionic species present in an atmospheric-pressure parallel plate dielectric barrier discharge (DBD) with a single dielectric on the powered electrode have been identified. The discharge was driven in helium with controllable concentrations of water vapour using an excitation frequency of 10 kHz and an applied voltage of 1.2 kV. Both negative and positive ions were identified and their relative intensity determined with variation of water concentration in the discharge, inter-electrode spacing, gas residence time and nominal applied power. The most abundant negative ions were of the family \\text{O}{{\\text{H}}-}{{≤ft({{\\text{H}}2}\\text{O}\\right)}n} , while the positive ions were dominated by those of the form {{{H}}^ + }{{{(}}{{{H}}_2}{{O)}}_n} , with n up to 9 in both cases. Negative and positive ions responded in a similar way to changes in the operating parameters, with the particular response depending on the ion mass. Increasing the inter-electrode spacing and the water concentration in the discharge led to an increase in the intensity of large mass ionic water clusters. However, increasing the residence time of the species in the plasma region and increasing the applied power resulted in fragmentation of large water clusters to produce smaller ions.

  14. High frequency excitation waveform for efficient operation of a xenon excimer dielectric barrier discharge lamp

    NASA Astrophysics Data System (ADS)

    Beleznai, Sz; Mihajlik, G.; Maros, I.; Balázs, L.; Richter, P.

    2010-01-01

    The application of a high frequency (~2.5 MHz) burst (amplitude-modulated sinusoidal) excitation voltage waveform is investigated for driving a fluorescent dielectric barrier discharge (DBD) light source. The excitation waveform presents a novel method for generating spatially stable homogeneous Xe DBD possessing a high conversion efficiency from electrical energy to VUV Xe_{2}^{\\ast} excimer radiation (~172 nm), even at a significantly higher electrical energy deposition than realized by pulsed excitation. Simulation and experimental results predict discharge efficiencies around 60%. Lamp efficacy above 74 lm W-1 has been achieved. VUV emission and loss mechanisms are investigated extensively and the performance of burst and pulsed waveforms is compared both theoretically and experimentally.

  15. Observations of soft X-ray emission and plasma dynamics of a compact capillary discharge operated in xenon

    SciTech Connect

    Valenzuela, J. C.; Wyndham, E. S.; Favre, M.; Chuaqui, H.

    2013-09-15

    We report observations of a low stored energy, low inductance compact capillary discharge operated in xenon. Even though the stored electrical energy is less than 1 J, significant output in the optical windows at 110 and 135 Å is measured. The soft X-ray emission is time-resolved and the conversion energy of the source is obtained. A lower bound to the conversion efficiency at 110 Å ± 2% and 135 Å ± 1% of 3.6% and 1.6% is obtained, respectively. The use of moiré-schlieren optical diagnostic allows the evolution of the line electron density. In particular, we observe a significant degree of compression in a tight on axis pinch as well as radial compression waves. The temporal evolution of the X-ray emission, which occurs during the current reversal and later, is discussed in relation to work in argon discharges and in relation to model calculations.

  16. Corrective Action Decision Document (CADD), Area 12 fleet operations steam cleaning discharge area, Nevada Test Site Corrective Action Unit 339

    SciTech Connect

    Bonn, J.F.

    1996-12-01

    This Corrective Action Decision Document (CADD) incorporates the methodology used for evaluating the remedial alternatives completed for a former steam cleaning discharge area at the Nevada Test Site (NTS). The former steam cleaning site is located in Area 12, east of the Fleet Operations Building 12-16. The discharge area has been impacted by Resource Conservation and Recovery Act (RCRA) F Listed volatile organic compounds (VOCs) and petroleum hydrocarbons waste. Based upon these findings, resulting from Phase 1 and Phase 2 site investigations, corrective action is required at the site. To determine the appropriate corrective action to be proposed, an evaluation of remedial alternatives was completed. The evaluation was completed using a Corrective Measures Study (CMS). Based on the results of the CMS, the favored closure alternative for the site is plugging the effluent discharge line, removing the sandbagged barrier, completing excavation of VOC impacted soils, and fencing the soil area impacted by total petroleum hydrocarbons (TPH), east of the discharge line and west of the soil berm. Management of the F Listed VOCs are dictated by RCRA. Due to the small volume of impacted soil, excavation and transportation to a Treatment Storage and Disposal Facility (TSDF) is the most practical method of management. It is anticipated that the TPH (as oil) impacted soils will remain in place based upon; the A through K Analysis, concentrations detected (maximum 8,600 milligrams per kilogram), expected natural degradation of the hydrocarbons over time, and the findings of the Phase 2 Investigation that vertical migration has been minimal.

  17. All-fiber passively mode-locked Tm-doped NOLM-based oscillator operating at 2-μm in both soliton and noisy-pulse regimes.

    PubMed

    Li, Jianfeng; Zhang, Zuxing; Sun, Zhongyuan; Luo, Hongyu; Liu, Yong; Yan, Zhijun; Mou, Chengbo; Zhang, Lin; Turitsyn, Sergei K

    2014-04-01

    A self-starting all-fiber passively mode-locked Tm(3+)-doped fiber laser based on nonlinear loop mirror (NOLM) is demonstrated. Stable soliton pulses centered at 2017.33 nm with 1.56 nm FWHM were produced at a repetition rate of 1.514 MHz with pulse duration of 2.8 ps and pulse energy of 83.8 pJ. As increased pump power, the oscillator can also operate at noise-like (NL) regime. Stable NL pulses with coherence spike width of 341 fs and pulse energy of up to 249.32 nJ was achieved at a center wavelength of 2017.24 nm with 21.33 nm FWHM. To the best of our knowledge, this is the first 2 µm region NOLM-based mode-locked fiber laser operating at two regimes with the highest single pulse energy for NL pulses. PMID:24718163

  18. Influence of different laser operation regimes on the specific energy required for rock removal in oil and gas well drilling applications

    NASA Astrophysics Data System (ADS)

    Albert, Florian; Grimm, Alexander; Schmidt, Michael; Cournoyer, Alain; Briand, Martin; Galarneau, Pierre

    2009-06-01

    Although many practical hurdles remain to be addressed in the future, laser oil and gas well drilling has potential advantages over the conventional rotary drilling approach, such as a smaller footprint of the drilling rig, higher rates of penetration, reduction of downtime due to dull bits, reduction of waste caused by drilling mud, creation of a natural casing while drilling, and ability to drill in hard rock formations. One of the most promising applications is downhole laser perforation for well completion as an alternative to explosive technologies currently in use. In order to establish both the technical and economic feasibility of using lasers in oil and gas drilling operations, one can measure the laser energy required to remove a unit volume of rock. The resulting specific energy is a measure of the efficiency of the laser drilling process and depends on the rock type and the laser operation regime that determines the laser-rock interaction mechanism. In the present feasibility study, we compare the results of laser drilling tests conducted in two types of reservoir rocks, namely limestone and sandstone, at different laser wavelengths and for different laser operation regimes (continuous wave and pulsed regimes, different repetition rates and duty cycles) in terms of specific energy. We also discuss preliminary results on the influence of the temporal shape of the laser pulses in the nanosecond regime on the rock removal process as obtained with INO pulse-shaping fiber laser platform, with the objective to take advantage of the flexibility and the agility of such a laser source for drilling operations in different rock types.

  19. Investigation of the laser pumping power impact on the operating regimes of a laser passively Q-switched by a saturated absorber

    NASA Astrophysics Data System (ADS)

    Benarab, Mustapha; Mokdad, Rabah; Djellout, Hocine; Benfdila, Arezki; Lamrous, Omar; Meyrueis, Patrick

    2011-09-01

    We have adapted the point model for the study of an all-fiber laser doped with Nd3+ and Q-switched by a saturable fiber absorber doped with Cr4+. Calculations of the output power of the 1084 nm laser are considered as a function of the pump power supplied by a 790 nm laser diode. The analysis of the simulation results reveals the existence of pulsed, sinusoidal, and dc operating regimes.

  20. Development in DIII-D of High Beta Discharges Appropriate for Steady-state Tokamak Operation With Burning Plasmas

    SciTech Connect

    Ferron, J R; Basiuk, V; Casper, T A; Challis, C D; DeBoo, J C; Doyle, E J; Gao, Q; Garofalo, A M; Greenfield, C M; Holcomb, C T; Hyatt, A W; Ide, S; Luce, T C; Murakami, M; Ou, Y; Park, J; Petrie, T W; Petty, C C; Politzer, P A; Reimerdes, H; Schuster, E; Schneider, M; Wang, A

    2008-10-13

    Ideally, tokamak power plants will operate in steady-state at high fusion gain. Recent work at DIII-D on the development of suitable high beta discharges with 100% of the plasma current generated noninductively (f{sub NI} = 1) is described. In a discharge with 1.5 < q{sub min} <2, a scan of the discharge shape squareness was used to find the value that maximizes confinement and achievable {beta}{sub N}. A small bias of the up/down balance of the double-null divertor shape away from the ion B x {del}B drift direction optimizes pumping for minimum density. Electron cyclotron current drive with a broad deposition profile was found to be effective at avoidance of a 2/1 NTM allowing long duration at {beta}{sub N} = 3.7. With these improvements, surface voltage {approx} 0-10 mV, indicating f{sub NI} {approx} 1, was obtained for 0.7 {tau}{sub R} (resistive time). Stationary discharges with {beta}{sub N} = 3.4 and f{sub NI} {approx} 0.9 that project to Q = 5 in ITER have been demonstrated for {tau}{sub R}. For use in development of model based controllers for the q profile, transport code models of the current profile evolution during discharge formation have been validated against the experiment. Tests of available actuators confirm that electron heating during the plasma current ramp up to modify the conductivity is by far the most effective. The empirically designed controller has been improved by use of proportional/integral gain and built-in limits to {beta}{sub N} to avoid instabilities. Two alternate steady-state compatible scenarios predicted to be capable of reaching {beta}{sub N} = 5 have been tested experimentally, motivated by future machines that require high power density and neutron fluence. In a wall stabilized scenario with q{sub min} > 2, {beta}{sub N} = 4 has been achieved for 2 s {approx} {tau}{sub R}. In a high internal inductance scenario, which maximizes the ideal no-wall stability limit, {beta}{sub N} {approx} 4.8 has been reached with f{sub NI} > 1.

  1. 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.

  2. Progress toward fully noninductive discharge operation in DIII-D using off-axis neutral beam injectiona)

    NASA Astrophysics Data System (ADS)

    Ferron, J. R.; Holcomb, C. T.; Luce, T. C.; Park, J. M.; Politzer, P. A.; Turco, F.; Heidbrink, W. W.; Doyle, E. J.; Hanson, J. M.; Hyatt, A. W.; In, Y.; La Haye, R. J.; Lanctot, M. J.; Okabayashi, M.; Petrie, T. W.; Petty, C. C.; Zeng, L.

    2013-09-01

    The initial experiments on off-axis neutral beam injection into high noninductive current fraction (fNI), high normalized pressure (βN) discharges in DIII-D [J. L. Luxon, Fusion Sci. Technol. 48, 828 (2005)] have demonstrated changes in the plasma profiles that increase the limits to plasma pressure from ideal low-n instabilities. The current profile is broadened and the minimum value of the safety factor (qmin) can be maintained above 2 where the profile of the thermal component of the plasma pressure is found to be broader. The off-axis neutral beam injection results in a broadening of the fast-ion pressure profile. Confinement of the thermal component of the plasma is consistent with the IPB98(y,2) scaling, but global confinement with qmin>2 is below the ITER-89P scaling, apparently as a result of enhanced transport of fast ions. A 0-D model is used to examine the parameter space for fNI=1 operation and project the requirements for high performance steady-state discharges. Fully noninductive solutions are found with 4<βN<5 and bootstrap current fraction near 0.5 for a weak shear safety factor profile. A 1-D model is used to show that a fNI=1 discharge at the top of this range of βN that is predicted stable to n =1, 2, and 3 ideal MHD instabilities is accessible through further broadening of the current and pressure profiles with off-axis neutral beam injection and electron cyclotron current drive.

  3. Hairpin resonator probes with frequency domain boxcar operation for time resolved density measurements in pulsed RF discharges

    NASA Astrophysics Data System (ADS)

    Peterson, David; Kummerer, Theresa; Coumou, David; Shannon, Steven

    2014-10-01

    In this work, microsecond time resolved electron density measurements in pulsed RF discharges are shown using an automated hairpin resonance probe using relatively low cost electronics, on par with normal Langmuir probe boxcar mode operation. A low cost signal generator is used to produce the applied microwave frequency and the reflected waveform is filtered to remove the RF component. The signal is then heterodyned with a simple frequency mixer to produce a dc signal read by an oscilloscope to determine the electron density. The applied microwave frequency is automatically shifted in small increments in a frequency boxcar routine through a Labview™program to determine the resonant frequency. A simple dc sheath correction is then easily applied since the probe is fully floating, producing low cost, high fidelity, and highly reproducible electron density measurements. The measurements are made in a capacitively coupled, parallel plate configuration in a 13.56 MHz, 50--200 W RF discharge pulsed at 500 Hz, 200 W, 50% duty cycle. The gas input ranged from 50--100 mTorr pure Ar or with 5--10% O/He mixtures.

  4. Calibration of a rainfall-runoff model at regional scale by optimising river discharge statistics: Performance analysis for the average/low flow regime

    NASA Astrophysics Data System (ADS)

    Lombardi, Laura; Toth, Elena; Castellarin, Attilio; Montanari, Alberto; Brath, Armando

    Traditional procedures for rainfall-runoff model calibration are generally based on the fit of individual values of simulated and observed hydrographs. We use here an alternative option that is carried out by matching, in the optimisation process, a set of streamflow statistics. Such an approach has the significant advantage to enable also a straightforward regional calibration of model parameters, based on the regionalisation of the selected statistics. The minimisation of the set of objective functions is carried out by using the AMALGAM algorithm, leading to the identification of behavioural parameter sets. The procedure is applied to a set of river basins located in central Italy: the basins are treated alternatively as gauged and ungauged and, as a term of comparison, the results obtained with a traditional time-domain calibration are also presented. With respect to previous applications of analogous procedures, we investigate here the identification of the target statistics depending on the purposes of the application, and in particular when the focus is on the reproduction of the low-flows. The results show that a suitable choice of the statistics to be optimised leads to interesting results in real world case studies as far as the reproduction of the different flow regimes is concerned.

  5. Barium Depletion in the NSTAR Discharge Cathode After 30,000 Hours of Operation

    NASA Technical Reports Server (NTRS)

    Polk, James E.; Capece, Angela M.; Mikellides, Ioannis G.; Katz, Ira

    2010-01-01

    Dispenser hollow cathodes rely on a consumable supply of barium released by impregnant materials in the pores of a tungsten matrix to maintain a low work function surface. Examinations of cathode inserts from long duration ion engine tests show deposits of tungsten at the downstream end that appear to block the flow of barium from the interior. In addition, a numerical model of barium transport in the insert plasma indicates that the barium partial pressure in the insert may exceed the equilibrium vapor pressure of the dominant barium-producing reaction, and it was postulated previously that this would suppress barium loss in the upstream part of the insert. New measurements of the depth of barium depletion from a cathode insert operated for 30,352 hours reveal that barium loss is confined to a narrow region near the downstream end, confirming this hypothesis.

  6. Numerical simulation of operation modes in atmospheric pressure uniform barrier discharge excited by a saw-tooth voltage

    SciTech Connect

    Li Xuechen; Niu Dongying; Yin Zengqian; Fang Tongzhen; Wang Long

    2012-08-15

    The characteristics of dielectric barrier discharge excited by a saw-tooth voltage are simulated in atmospheric pressure helium based on a one-dimensional fluid model. A stepped discharge is obtained per half voltage cycle with gas gap width less than 2 mm by the simulation, which is different to the pulsed discharge excited by a sinusoidal voltage. For the stepped discharge, the plateau duration increases with increasing the voltage amplitude and decreasing the gas gap. Therefore, uniform discharge with high temporal duty ratio can be realized with small gap through increasing the voltage amplitude. The maximal densities of both electron and ion appear near the anode and the electric field is almost uniformly distributed along the gap, which indicates that the stepped discharge belongs to a Townsend mode. In contrast to the stepped discharge with small gas gap, a pulsed discharge can be obtained with large gas gap. Through analyzing the spatial density distributions of electron and ion and the electric field, the pulsed discharge is in a glow mode. The voltage-current (V-I) characteristics are analyzed for the above mentioned discharges under different gas gaps, from which the different discharge modes are verified.

  7. Numerical simulation of operation modes in atmospheric pressure uniform barrier discharge excited by a saw-tooth voltage

    NASA Astrophysics Data System (ADS)

    Li, Xuechen; Niu, Dongying; Yin, Zengqian; Fang, Tongzhen; Wang, Long

    2012-08-01

    The characteristics of dielectric barrier discharge excited by a saw-tooth voltage are simulated in atmospheric pressure helium based on a one-dimensional fluid model. A stepped discharge is obtained per half voltage cycle with gas gap width less than 2 mm by the simulation, which is different to the pulsed discharge excited by a sinusoidal voltage. For the stepped discharge, the plateau duration increases with increasing the voltage amplitude and decreasing the gas gap. Therefore, uniform discharge with high temporal duty ratio can be realized with small gap through increasing the voltage amplitude. The maximal densities of both electron and ion appear near the anode and the electric field is almost uniformly distributed along the gap, which indicates that the stepped discharge belongs to a Townsend mode. In contrast to the stepped discharge with small gas gap, a pulsed discharge can be obtained with large gas gap. Through analyzing the spatial density distributions of electron and ion and the electric field, the pulsed discharge is in a glow mode. The voltage-current (V-I) characteristics are analyzed for the above mentioned discharges under different gas gaps, from which the different discharge modes are verified.

  8. Laser frequency stabilisation by the Pound - Drever - Hall method using an acousto-optic phase modulator operating in the pure Raman - Nath diffraction regime

    SciTech Connect

    Baryshev, Vyacheslav N

    2012-04-30

    Frequency stabilisation of diode laser radiation has been implemented by the Pound - Drever - Hall method using a new acousto-optic phase modulator, operating in the pure Raman - Nath diffraction regime. It is experimentally shown that, as in the case of saturated-absorption spectroscopy in atomic vapour, the spatial divergence of the frequency-modulated output spectrum of this modulator does not interfere with obtaining error signals by means of heterodyne frequency-modulation spectroscopy with a frequency discriminator based on a high-Q Fabry - Perot cavity with finesse of several tens of thousands.

  9. An operator perturbation method for polarized line transfer. I. Non-magnetic regime in 1D media.

    NASA Astrophysics Data System (ADS)

    Faurobert-Scholl, M.; Frisch, H.; Nagendra, K. N.

    1997-06-01

    In this paper we generalize an Approximate Lambda Iteration (ALI) technique developed for scalar transfer problems to a vectorial transfer problem for polarized radiation. Scalar ALI techniques are based on a suitable decomposition of the Lambda operator governing the integral form of the transfer equation. Lambda operators for scalar transfer equations are diagonally dominant, offering thus the possibility to use iterative methods of the Jacobi type where the iteration process is based on the diagonal of the Lambda operator (Olson et al., 1986, JQSRT 35, 431). Here we consider resonance polarization, created by the scattering of an anisotropic radiation field, for spectral lines formed with complete frequency redistribution in a 1D axisymmetric medium. The problem can be formulated as an integral equation for a 2-component vector (Rees, 1978PASJ...30..455R) or, as shown by Ivanov (1995A&A...303..621I), as an integral equation for a (2x2) matrix source function which involves the same generalized Lambda operator as the vector integral equation. We find that this equation holds also in the presence of a weak turbulent magnetic field. The generalized Lambda operator is a (2x2) matrix operator. The element {11} describes the propagation of the intensity and is identical to the Lambda operator of non-polarized problems. The element {22} describes the propagation of the polarization. The off-diagonal terms weakly couple the intensity and the polarization. We propose a block Jacobi iterative method and show that its convergence properties are controlled by the propagator for the intensity. We also show that convergence can be accelerated by an Ng acceleration method applied to each element of the source matrix. We extend to polarized transfer a convergence criterion introduced by Auer et al. (1994A&A...292..599A) based on the grid truncation error of the converged solution.

  10. Similarities and differences between gliding glow and gliding arc discharges

    NASA Astrophysics Data System (ADS)

    Kolev, St.; Bogaerts, A.

    2015-12-01

    In this work we have analyzed the properties of a gliding dc discharge in argon at atmospheric pressure. Despite the usual designation of these discharges as ‘gliding arc discharges’, it was found previously that they operate in two different regimes—glow and arc. Here we analyze the differences in both regimes by means of two dimensional fluid modeling. In order to address different aspects of the discharge operation, we use two models—Cartesian and axisymmetric in a cylindrical coordinate system. The obtained results show that the two types of discharges produce a similar plasma column for a similar discharge current. However, the different mechanisms of plasma channel attachment to the cathode could produce certain differences in the plasma parameters (i.e. arc elongation), and this can affect gas treatments applications.

  11. Magnetic dipole discharges. II. Cathode and anode spot discharges and probe diagnostics

    SciTech Connect

    Stenzel, R. L.; Urrutia, J. M.; Ionita, C.; Schrittwieser, R.

    2013-08-15

    The high current regime of a magnetron-type discharge has been investigated. The discharge uses a permanent magnet as a cold cathode which emits secondary electrons while the chamber wall or a grounded electrode serves as the anode. As the discharge voltage is increased, the magnet develops cathode spots, which are short duration arcs that provide copious electrons to increase the discharge current dramatically. Short (1 μs), high current (200 A) and high voltage (750 V) discharge pulses are produced in a relaxation instability between the plasma and a charging capacitor. Spots are also observed on a negatively biased plane Langmuir probe. The probe current pulses are as large as those on the magnet, implying that the high discharge current does not depend on the cathode surface area but on the properties of the spots. The fast current pulses produce large inductive voltages, which can reverse the electrical polarity of the magnet and temporarily operate it as an anode. The discharge current may also oscillate at the frequency determined by the charging capacitor and the discharge circuit inductance. Each half cycle of high-current current pulses exhibits a fast (≃10 ns) current rise when a spot is formed. It induces high frequency (10–100 MHz) transients and ringing oscillations in probes and current circuits. Most probes behave like unmatched antennas for the electromagnetic pulses of spot discharges. Examples are shown to distinguish the source of oscillations and some rf characteristics of Langmuir probes.

  12. Field application of selective precipitation for recovering Cu and Zn in drainage discharged from an operating mine.

    PubMed

    Oh, Chamteut; Han, Young-Soo; Park, Jin Hee; Bok, Songmin; Cheong, Youngwook; Yim, Giljae; Ji, Sangwoo

    2016-07-01

    Acid mine drainage (AMD) generated from mining activities has been recognized as a serious problem due to its increased acidity and high concentration of heavy metals. In this research, a feasibility test of the selective precipitation (SP) process was performed using AMD discharged from a currently operating mine in Korea for the purpose of minimizing the environmental impact of AMD. For the SP process, a pilot scale equipment (100L reaction tank) was used in field and among various metals, Cu and Zn were the target metals. Through the research, it was confirmed that AMD from an operating mine has two disadvantages of being applied to the SP: altering water quality and unexpected inclusion of clay debris. Despite unfavorable conditions, Cu and Zn precipitate of 80% purity with 90% precipitation rate was able to be obtained from 1.4L/min (2.0tons/day) AMD. The recovered precipitates were identified as amorphous CuS and ZnS with small amounts of impurities (Si minerals, CuFeS2, and Fe/Al hydroxide). The strategies to reduce these impurities were also discussed. Recovery rate, which is the amount of precipitate collected per unit volume of AMD, was proposed as an indicator to evaluate the working efficiency of the SP process. It was confirmed that the recovery rate was strongly dependent on flow rate and dose of coagulant. The results of this study may be helpful in reducing the potential complications which occurs when SP is applied on field. PMID:26994808

  13. Lung surgery - discharge

    MedlinePlus

    Thoracotomy - discharge; Lung tissue removal - discharge; Pneumonectomy - discharge; Lobectomy - discharge; Lung biopsy - discharge; Thoracoscopy - discharge; Video-assisted thoracoscopic surgery - discharge; VATS - discharge; Thoracoscopy - discharge

  14. A controllable noise-like operation regime in a Yb-doped dispersion-mapped fiber ring laser

    NASA Astrophysics Data System (ADS)

    Zaytsev, A. K.; Lin, C. H.; You, Y. J.; Tsai, F. H.; Wang, C. L.; Pan, C. L.

    2013-04-01

    We report the generation of tunable high-energy noise-like pulses with a super-broadband spectrum from a Yb-doped dispersion-mapped fiber ring laser. Self-starting noise-like operation can be maintained over a relatively large range of pumping powers (4-13 W). The corresponding output power varies from 0.1 to 1.45 W. The maximum 3 dB spectral bandwidth of the noise-like pulses is about 48.2 nm while the output energy is as high as 47 nJ, limited by optical damage of the components. The central wavelength of the noise-like pulses can be tuned easily over ˜12 nm. The bandwidth and duration of the generated wave packets can also be controlled. The use of a negative dispersion-delay line and spectral filter are found to be important for generating such high-power noise-like operation. Experimental results are in good agreement with theoretical simulations.

  15. On the bipolar resistive-switching characteristics of Al₂O₃- and HfO₂-based memory cells operated in the soft-breakdown regime

    SciTech Connect

    Goux, L. Fantini, A.; Nigon, R.; Strangio, S.; Degraeve, R.; Kar, G.; Chen, Y. Y.; Jurczak, M.; Raghavan, N.; De Stefano, F.; Afanas'ev, V. V.

    2014-10-07

    In this article, we investigate extensively the bipolar-switching properties of Al₂O₃- and HfO₂-based resistive-switching memory cells operated at low current down to <1 μA. We show that the switching characteristics differ considerably from those typically reported for larger current range (>15 μA), which we relate as intrinsic to soft-breakdown (SBD) regime. We evidence a larger impact of the used switching-oxide in this current range, due to lower density of oxygen-vacancy (V{sub o}) defects in the SBD regime. In this respect, deep resetting and large memory window may be achieved using the stoichiometric Al₂O₃ material due to efficient V{sub o} annihilation, although no complete erasure of the conductive-filament (CF) is obtained. We finally emphasize that the conduction may be described by a quantum point-contact (QPC) model down to very low current level where only a few V{sub o} defects compose the QPC constriction. The large switching variability inherent to this latter aspect is mitigated by CF shape tuning through adequate engineering of an Al₂O₃\\HfO₂ bilayer.

  16. National Scale Operational Mapping of Burnt Areas as a Tool for the Better Understanding of Contemporary Wildfire Patterns and Regimes

    PubMed Central

    Kontoes, Charalampos; Keramitsoglou, Iphigenia; Papoutsis, Ioannis; Sifakis, Nicolas I.; Xofis, Panteleimon

    2013-01-01

    This paper presents the results of an operational nationwide burnt area mapping service realized over Greece for the years 2007–2011, through the implementation of the so-called BSM_NOA dedicated method developed at the National Observatory of Athens for post-fire recovery management. The method exploits multispectral satellite imagery, such as Landsat-TM, SPOT, FORMOSAT-2, WorldView and IKONOS. The analysis of fire size distribution reveals that a high number of fire events evolve to large and extremely large wildfires under favorable wildfire conditions, confirming the reported trend of an increasing fire-severity in recent years. Furthermore, under such conditions wildfires affect to a higher degree areas at high altitudes, threatening the existence of ecologically significant ecosystems. Finally, recent socioeconomic changes and land abandonment has resulted in the encroachment of former agricultural areas of limited productivity by shrubs and trees, resulting both in increased fuel availability and continuity, and subsequently increased burnability. PMID:23966201

  17. High-power free-electron maser operated in a two-mode frequency-multiplying regime

    NASA Astrophysics Data System (ADS)

    Peskov, N. Yu.; Bandurkin, I. V.; Kaminsky, A. K.; Kuzikov, S. V.; Perelstein, E. A.; Savilov, A. V.; Sedykh, S. N.; Vikharev, A. A.

    2016-06-01

    The frequency multiplication effects in high-power free-electron masers (FEM) with Bragg cavities were studied to provide the advance of the oscillators into short-wavelength bands. Theoretical analysis of frequency-multiplying FEMs was carried out within the framework of the averaged coupled-wave approach. Proof-of-principle experiments were performed based on a moderately relativistic induction linac LIU-3000 (JINR). As a result, an FEM multiplier operated with a megawatt power level in the 6-mm and 4-mm wavelength bands at the second and third harmonics, respectively, was realized. The possibility of using two-mode bichromatic FEMs for powering a double-frequency accelerating structure was discussed.

  18. National scale operational mapping of burnt areas as a tool for the better understanding of contemporary wildfire patterns and regimes.

    PubMed

    Kontoes, Charalampos; Keramitsoglou, Iphigenia; Papoutsis, Ioannis; Sifakis, Nicolas I; Xofis, Panteleimon

    2013-01-01

    This paper presents the results of an operational nationwide burnt area mapping service realized over Greece for the years 2007-2011, through the implementation of the so-called BSM_NOA dedicated method developed at the National Observatory of Athens for post-fire recovery management. The method exploits multispectral satellite imagery, such as Landsat-TM, SPOT, FORMOSAT-2, WorldView and IKONOS. The analysis of fire size distribution reveals that a high number of fire events evolve to large and extremely large wildfires under favorable wildfire conditions, confirming the reported trend of an increasing fire-severity in recent years. Furthermore, under such conditions wildfires affect to a higher degree areas at high altitudes, threatening the existence of ecologically significant ecosystems. Finally, recent socioeconomic changes and land abandonment has resulted in the encroachment of former agricultural areas of limited productivity by shrubs and trees, resulting both in increased fuel availability and continuity, and subsequently increased burnability. PMID:23966201

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

    SciTech Connect

    Liu, Fucheng He, Yafeng; Dong, Lifang

    2014-12-15

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

  20. Co-operation and conflict under hard and soft contracting regimes: case studies from England and Wales

    PubMed Central

    2013-01-01

    Background This paper examines NHS secondary care contracting in England and Wales in a period which saw increasing policy divergence between the two systems. At face value, England was making greater use of market levers and utilising harder-edged service contracts incorporating financial penalties and incentives, while Wales was retreating from the 1990s internal market and emphasising cooperation and flexibility in the contracting process. But there were also cross-border spill-overs involving common contracting technologies and management cultures that meant that differences in on-the-ground contracting practices might be smaller than headline policy differences suggested. Methods The nature of real-world contracting behaviour was investigated by undertaking two qualitative case studies in England and two in Wales, each based on a local purchaser/provider network. The case studies involved ethnographic observations and interviews with staff in primary care trusts (PCTs) or local health boards (LHBs), NHS or Foundation trusts, and the overseeing Strategic Health Authority or NHS Wales regional office, as well as scrutiny of relevant documents. Results Wider policy differences between the two NHS systems were reflected in differing contracting frameworks, involving regional commissioning in Wales and commissioning by either a PCT, or co-operating pair of PCTs in our English case studies, and also in different oversight arrangements by higher tiers of the service. However, long-term relationships and trust between purchasers and providers had an important role in both systems when the financial viability of organisations was at risk. In England, the study found examples where both PCTs and trusts relaxed contractual requirements to assist partners faced with deficits. In Wales, news of plans to end the purchaser/provider split meant a return to less precisely-specified block contracts and a renewed concern to build cooperation between LHB and trust staff

  1. Flight tests of Viking parachute system in three Mach number regimes. 1: Vehicle description, test operations, and performance

    NASA Technical Reports Server (NTRS)

    Lundstrom, R. R.; Raper, J. L.; Bendura, R. J.; Shields, E. W.

    1974-01-01

    Flight qualifications for parachutes were tested on full-scale simulated Viking spacecraft at entry conditions for the Viking 1975 mission to Mars. The vehicle was carried to an altitude of 36.6 km for the supersonic and transonic tests by a 980.000 cu m balloon. The vehicles were released and propelled to test conditions with rocket engines. A 117,940 cu m balloon carried the test vehicle to an altitude of 27.5 km and the conditions for the subsonic tests were achieved in free fall. Aeroshell separation occurred on all test vehicles from 8 to 14 seconds after parachute deployment. This report describes: (1) the test vehicle; (2) methods used to insure that the test conditions were achieved; and (3) the balloon system design and operations. The report also presents the performance data from onboard and ground based instruments and the results from a statistical trajectory program which gives a continuous history of test-vehicle motions.

  2. Regime change?

    SciTech Connect

    Pilat, Joseph F.; Budlong-Sylvester, K. W.

    2004-01-01

    Following the 1998 nuclear tests in South Asia and later reinforced by revelations about North Korean and Iraqi nuclear activities, there has been growing concern about increasing proliferation dangers. At the same time, the prospects of radiological/nuclear terrorism are seen to be rising - since 9/11, concern over a proliferation/terrorism nexus has never been higher. In the face of this growing danger, there are urgent calls for stronger measures to strengthen the current international nuclear nonproliferation regime, including recommendations to place civilian processing of weapon-useable material under multinational control. As well, there are calls for entirely new tools, including military options. As proliferation and terrorism concerns grow, the regime is under pressure and there is a temptation to consider fundamental changes to the regime. In this context, this paper will address the following: Do we need to change the regime centered on the Treaty on the Nonproliferation of Nuclear Weapons (NPT) and the International Atomic Energy Agency (IAEA)? What improvements could ensure it will be the foundation for the proliferation resistance and physical protection needed if nuclear power grows? What will make it a viable centerpiece of future nonproliferation and counterterrorism approaches?

  3. Kidney stones - lithotripsy - discharge

    MedlinePlus

    Extracorporeal shock wave lithotripsy - discharge; Shock wave lithotripsy - discharge; Laser lithotripsy - discharge; Percutaneous lithotripsy - discharge; Endoscopic lithotripsy - discharge; ESWL - discharge

  4. Pancreatitis - discharge

    MedlinePlus

    Chronic pancreatitis - discharge; Pancreatitis - chronic - discharge; Pancreatic insufficiency - discharge; Acute pancreatitis - discharge ... You were in the hospital because you have pancreatitis. This is a swelling of the pancreas. You ...

  5. Breakdown and dc discharge in low-pressure water vapour

    NASA Astrophysics Data System (ADS)

    Sivoš, J.; Škoro, N.; Marić, D.; Malović, G.; Petrović, Z. Lj

    2015-10-01

    In this paper we report studies of basic properties of breakdown, low-current Townsend discharge and high-current discharge regimes in water vapour. Paschen curves and the corresponding distributions of emission intensities at low current were recorded in the range of pd (pressure x electrode gap) from 0.1 to 10 Torrcm covering the region of Paschen minimum. From the experimental profiles we obtained effective ionization coefficient of water vapour for the E/N range 650 Td-7 kTd and fitted the results by using the extended Townsend analytical formula. Using the obtained ionization coefficient, we calculated the effective yield of secondary electrons from the copper cathode. Results of the measurements of Volt-Ampere characteristics in water vapour were presented together with the images of the axial structure of the discharge in a wide range of discharge currents for two pd values. Recorded profiles showed development of the spatial structure of the discharge in different operating regimes. We were able to identify conditions where processes induced by heavy particles, probably fast hydrogen atoms, are dominant in inducing emission from the discharge. Finally, standard scaling laws were tested for low current and glow discharges in water vapour.

  6. Determining local temperatures in the structures of AlInGaP/GaAs red LEDs in a pulsed operation regime

    NASA Astrophysics Data System (ADS)

    Sergeev, V. A.; Shirokov, A. A.

    2009-05-01

    The emission spectra of AlInGaP/GaAs red light-emitting diodes (LEDs) based on a multi-quantum-well heterostructure with distributed Bragg reflectors, operating in a pulsed mode with a pulse repetition rate within 1-10 kHz and a current of 1 × 10-3-2 × 10-1 A have been studied in the 20-100°C temperature range. In the regimes with short current pulses and large off/duty ratios, which exclude self-heating of the LED structure, the temperature dependences of the wavelength of emission peaks in the main and side bands exhibit a super-and sublinear behavior, respectively. In the quasi-linear regions of these dependences, the temperature coefficient of wavelength shift for the main peak decreases, while that for the side peak weakly increases with increasing current. The local temperatures (determined from the spectral shift of the main and side emission peaks) and their difference increase with the pulse duration. The difference of thermal resistances, which is calculated from the slope of a plot of the local temperature versus average heating power, is independent of the current and determined by the parameters of layers separating the heterostructure from the reemission region.

  7. Role of climate forecasts and initial land-surface conditions in developing operational streamflow and soil moisture forecasts in a rainfall-runoff regime: skill assessment

    NASA Astrophysics Data System (ADS)

    Sinha, T.; Sankarasubramanian, A.

    2012-04-01

    Skillful seasonal streamflow forecasts obtained from climate and land surface conditions could significantly improve water and energy management. Since climate forecasts are updated on monthly basis, we evaluate the potential in developing operational monthly streamflow forecasts on a continuous basis throughout the year. Further, basins in the rainfall-runoff regime critically depend on the forecasted precipitation in the upcoming months as opposed to snowmelt regimes where initial hydrological conditions (IHC) play a critical role. The goal of this study is to quantify the role of monthly updated precipitation forecasts and IHC in forecasting 6-month lead monthly streamflow for a rainfall-runoff mechanism dominated basin - Apalachicola River at Chattahoochee, FL. The Variable Infiltration Capacity (VIC) land surface model is implemented with two forcings: (a) monthly updated precipitation forecasts from ECHAM4.5 Atmospheric General Circulation Model (AGCM) forced with sea surface temperature forecasts and (b) daily climatological ensemble. The difference in skill between the above two quantifies the improvements that could be attainable using the AGCM forecasts. Monthly retrospective streamflow forecasts are developed from 1981 to 2010 and streamflow forecasts estimated from the VIC model are also compared with those predicted by using the principal component regression (PCR) model. Mean square error (MSE) in predicting monthly streamflow using the above VIC model are compared with the MSE of streamflow climatology under ENSO conditions as well as under normal years. Results indicate that VIC forecasts, at 1-2 month lead time, obtained using ECHAM4.5 are significantly better than VIC forecasts obtained using climatological ensemble over all the seasons except forecasts issued in fall and the PCR models perform better during the fall months. Over longer lead times (3-6 months), VIC forecasts derived using ECHAM4.5 forcings alone performed better compared to the

  8. Dielectric barrier discharge-based plasma actuator operation in artificial atmospheres for validation of modeling and simulation

    NASA Astrophysics Data System (ADS)

    Mangina, R. S.; Enloe, C. L.; Font, G. I.

    2015-11-01

    We present an experimental case study of time-resolved force production by an aerodynamic plasma actuator immersed in various mixtures of electropositive (N2) and electronegative gases (O2 and SF6) at atmospheric pressure using a fixed AC high-voltage input of 16 kV peak amplitude at 200 Hz frequency. We have observed distinct changes in the discharge structures during both negative- and positive-going voltage half-cycles, with corresponding variations in the actuator's force production: a ratio of 4:1 in the impulse produced by the negative-going half-cycle of the discharge among the various gas mixtures we explored, 2:1 in the impulse produced by the positive-going half-cycle, and cases in which the negative-going half-cycle dominates force production (by a ratio of 1.5:1), where the half-cycles produce identical force levels, and where the positive-going half cycle dominates (by a ratio of 1:5). We also present time-resolved experimental evidence for the first time that shows electrons do play a significant role in the momentum coupling to surrounding neutrals during the negative going voltage half-cycle of the N2 discharge. We show that there is sufficient macroscopic variation in the plasma that the predictions of numerical models at the microscopic level can be validated even though the plasma itself cannot be measured directly on those spatial and temporal scales.

  9. Environmental and economic assessment of discharges from Gulf of Mexico Region oil and gas operation. Quarterly technical progress report, 1 October--31 December 1994

    SciTech Connect

    Gettleson, D.A.

    1995-01-18

    Task 3 (Environmental Field Sampling and Analysis of NORM, Heavy Metals, and Organics) work included analyses of samples. Task 4 (Monitoring of the Recovery of Impacted Wetland and Open Bay Produced Water Discharge Sites in Coastal Louisiana and Texas) activities involved the continued analyses of samples and field sampling at Bay de Chene. Task 5 (Assessment of Economic Impacts of Offshore and Coastal Discharge Requirements on Present and Future Operations in the Gulf of Mexico Region) activities included preparing a draft final report. Task 6 (Synthesis of Gulf of Mexico Seafood Consumption and Use Patterns) work also involved preparing a draft final report. Task 7 (Technology Transfer Plan) activities included a presentation at the Minerals Management Service Information Transfer Meeting for the Gulf of Mexico OCS Region. Task 8 (Project Management and Deliverables) activities involved the submission of the necessary reports and routine management.

  10. Lung surgery - discharge

    MedlinePlus

    Thoracotomy - discharge; Lung tissue removal - discharge; Pneumonectomy - discharge; Lobectomy - discharge; Lung biopsy - discharge; Thoracoscopy - discharge; Video-assisted thoracoscopic surgery - discharge; VATS - ...

  11. Hysterectomy - laparoscopic - discharge

    MedlinePlus

    Supracervical hysterectomy - discharge; Removal of the uterus - discharge; Laparoscopic hysterectomy - discharge; Total laparoscopic hysterectomy - discharge; TLH - discharge; Laparoscopic supracervical ...

  12. Shoulder replacement - discharge

    MedlinePlus

    Total shoulder arthroplasty - discharge; Endoprosthetic shoulder replacement - discharge; Partial shoulder replacement - discharge; Partial shoulder arthroplasty - discharge; Replacement - shoulder - discharge; ...

  13. Radical prostatectomy - discharge

    MedlinePlus

    ... prostatectomy - discharge; Laparoscopic radical prostatectomy - discharge; LRP - discharge; Robotic-assisted laparoscopic prostatectomy - discharge ; RALP - discharge; Pelvic lymphadenectomy - ...

  14. A laser gyro with a four-mirror square resonator: formulas for simulating the dynamics of the synchronisation zone parameters of the frequencies of counterpropagating waves during the device operation in the self-heating regime

    SciTech Connect

    Bondarenko, E A

    2014-04-28

    For a laser gyro with a four-mirror square resonator we have developed a mathematical model, which allows one to simulate the temporal behaviour of the synchronisation zone parameters of the frequencies of counterpropagating waves in a situation when the device operates in the self-heating regime and is switched-on at different initial temperatures. (laser gyroscopes)

  15. Reducing harmful emissions discharged into the atmosphere from operating boilers by applying a combination of low-cost technological measures

    NASA Astrophysics Data System (ADS)

    Roslyakov, P. V.; Ionkin, I. L.; Pleshanov, K. A.

    2010-12-01

    The operational methods for suppressing nitrogen oxide emissions widely used in gas-and-oil-fired boilers are described. Information is given on implementing integrated operational measures in BKZ-75-39GM and TGM-96B boilers.

  16. Dielectric barrier discharge-based plasma actuator operation in artificial atmospheres for validation of modeling and simulation

    SciTech Connect

    Mangina, R. S.; Enloe, C. L.; Font, G. I.

    2015-11-15

    We present an experimental case study of time-resolved force production by an aerodynamic plasma actuator immersed in various mixtures of electropositive (N{sub 2}) and electronegative gases (O{sub 2} and SF{sub 6}) at atmospheric pressure using a fixed AC high-voltage input of 16 kV peak amplitude at 200 Hz frequency. We have observed distinct changes in the discharge structures during both negative- and positive-going voltage half-cycles, with corresponding variations in the actuator's force production: a ratio of 4:1 in the impulse produced by the negative-going half-cycle of the discharge among the various gas mixtures we explored, 2:1 in the impulse produced by the positive-going half-cycle, and cases in which the negative-going half-cycle dominates force production (by a ratio of 1.5:1), where the half-cycles produce identical force levels, and where the positive-going half cycle dominates (by a ratio of 1:5). We also present time-resolved experimental evidence for the first time that shows electrons do play a significant role in the momentum coupling to surrounding neutrals during the negative going voltage half-cycle of the N{sub 2} discharge. We show that there is sufficient macroscopic variation in the plasma that the predictions of numerical models at the microscopic level can be validated even though the plasma itself cannot be measured directly on those spatial and temporal scales.

  17. Pre-breakdown evaluation of gas discharge mechanisms in microgaps

    SciTech Connect

    Semnani, Abbas; Peroulis, Dimitrios; Venkattraman, Ayyaswamy; Alexeenko, Alina A.

    2013-04-29

    The individual contributions of various gas discharge mechanisms to total pre-breakdown current in microgaps are quantified numerically. The variation of contributions of field emission and secondary electron emission with increasing electric field shows contrasting behavior even for a given gap size. The total current near breakdown decreases rapidly with gap size indicating that microscale discharges operate in a high-current, low-voltage regime. This study provides the first such analysis of breakdown mechanisms and aids in the formulation of physics-based theories for microscale breakdown.

  18. Kinetic simulations of magnetized capacitively coupled discharges

    NASA Astrophysics Data System (ADS)

    Trieschmann, Jan; Shihab, Mohammed; Eremin, Denis; Brinkmann, Ralf Peter; Schulze, Julian; Mussenbrock, Thomas

    2012-10-01

    Capacitive high frequency discharges are of crucial importance in the context of plasma etching, deposition and surface modification. As these single or multiple frequency discharges are oftentimes operated at low pressures of less than a few pascal, a high plasma density is commonly achieved with the use of external magnetic fields. In this work kinetic simulations are used to investigate the effect of inhomogeneous external magnetic fields on the discharge dynamics in a strongly nonlocal pressure regime. We found that capacitively coupled discharges can be largely asymmetrized by applying strong magnetic fields in front of a given target electrode. This not only has an effect on the plasma density, but also on the ion energy distribution functions (IEDF) at the electrodes and on the acceleration of fast electrons in the plasma sheath regions. In consequence in the discharge currents a generation of higher harmonics of the driving frequency can be observed. We investigate these scenarios in terms of 1D-3V Particle in Cell simulations.

  19. Contribution of positive and negative ions to the electrohydrodynamic force in a dielectric barrier discharge plasma actuator operating in air

    SciTech Connect

    Boeuf, J. P.; Lagmich, Y.; Pitchford, L. C.

    2009-07-15

    We present a parametric study of the electrohydrodynamic force generated by surface dielectric barrier discharge plasma actuators in air for sinusoidal voltage waveforms. The simulation results confirm that momentum is transferred from the charged particles to the neutral species in the same direction during both positive and negative parts of the cycle. The momentum transfer is due to positive ions during the positive part of the cycle (electrode above the dielectric layer is the anode), and to negative ions during the negative part of the cycle. The relative contribution of the positive and negative parts of the cycle depends on the voltage amplitude and frequency. The model predicts that the contribution of negative ions tends to be dominant at low voltage frequencies and high voltage amplitudes.

  20. Numerical simulation of the swirl generator discharge cone at lower runner speeds

    NASA Astrophysics Data System (ADS)

    Bosioc, A. I.; Muntean, S.; Susan-Resiga, R. F.; Vékás, L.; Bernad, S.

    2013-10-01

    The paper focuses on numerical analysis of hydrodynamic behavior in a discharge cone from a swirling flow generator when is operated at lower runner speeds. The swirl generator is used in laboratory instead of a turbine model in order to investigate different swirling flow configurations into a straight draft tube. The purpose for reducing the speed of the runner is to increase the investigation regimes. Numerical results have shown that reducing the speed of the runner from the swirl generator, we are able to obtain different flow configurations similar with a turbine model operated in a wide range of operating regimes.

  1. Burning plasma regime for Fussion-Fission Research Facility

    NASA Astrophysics Data System (ADS)

    Zakharov, Leonid E.

    2010-11-01

    The basic aspects of burning plasma regimes of Fusion-Fission Research Facility (FFRF, R/a=4/1 m/m, Ipl=5 MA, Btor=4-6 T, P^DT=50-100 MW, P^fission=80-4000 MW, 1 m thick blanket), which is suggested as the next step device for Chinese fusion program, are presented. The mission of FFRF is to advance magnetic fusion to the level of a stationary neutron source and to create a technical, scientific, and technology basis for the utilization of high-energy fusion neutrons for the needs of nuclear energy and technology. FFRF will rely as much as possible on ITER design. Thus, the magnetic system, especially TFC, will take advantage of ITER experience. TFC will use the same superconductor as ITER. The plasma regimes will represent an extension of the stationary plasma regimes on HT-7 and EAST tokamaks at ASIPP. Both inductive discharges and stationary non-inductive Lower Hybrid Current Drive (LHCD) will be possible. FFRF strongly relies on new, Lithium Wall Fusion (LiWF) plasma regimes, the development of which will be done on NSTX, HT-7, EAST in parallel with the design work. This regime will eliminate a number of uncertainties, still remaining unresolved in the ITER project. Well controlled, hours long inductive current drive operation at P^DT=50-100 MW is predicted.

  2. Achieving an intense enough maintenance electric field in a low-pressure discharge sustained by a microwave field under ambipolar diffusion regime such that periodic parametric instabilities are generated

    NASA Astrophysics Data System (ADS)

    Moisan, M.; Nowakowska, H.

    2015-11-01

    The intensity of the maintenance electric field of a given discharge is one of its internal parameters. Under ambipolar diffusion conditions, it is almost exclusively set by particle losses, which are related to the dimensions of the discharge vessel and to the gas pressure, and ultimately are determined by the electron energy distribution function. For instance, raising the density of microwave power absorbed in a discharge tube essentially increases the electron density without much increasing the amplitude of the maintenance E-field. To raise the intensity of this E-field in such a case, one needs to reduce the volume into which electromagnetic power is absorbed relative to the diffusion volume, i.e. the volume within which electrons transfer their power through collisions with heavy particles. To show this point, we consider a power balance based on the power lost per electron through collisions with heavy particles, θ L, to the power absorbed (over a period of the microwave field) per electron in the discharge, θ A. The power θ A, which depends on E02 , the square of the amplitude (intensity) of the maintenance electric field, adjusts to compensate for the power lost θ L. The analysis presented is achieved for a particular microwave discharge configuration that is known to provide an intense E 0-field, which means x  ⩾  λ De, where x is the oscillation amplitude of electrons in the E 0-field and λ De the electron Debye length. Such a condition allows one to observe periodic parametric instabilities at, or close to, the electron-plasma frequency f pe and at their corresponding ion-plasma frequency f pi, these oscillations being caused by the simultaneous propagation of an electron-plasma wave and an ion-plasma wave in the discharge as a result of an applied ‘pump’ power, which also sustains the discharge. A 2D hydrodynamic calculation of the specific plasma discharge system is performed, which yields the value of the x/λ De ratio in

  3. Experimental and analytical study of a high gain self amplified spontaneous emission free electron laser operating in a large spectral bandwidth regime

    NASA Astrophysics Data System (ADS)

    Andonian, Gerard Cosmos

    The drive to create and measure ultra-short pulses in the x-ray regime advances the ongoing development of free electron lasers (FEL). Several proposed schemes, to shorten the pulse length of the radiation, involve driving the FEL with a chirped (linear longitudinal phase space correlation) electron beam in the self amplified spontaneous emission (SASE) mode. This dissertation examines the experiments conducted under such conditions, canvassing analytical and numerical studies of beam dynamics and radiation properties, experimental observations, and descriptions of the development of novel diagnostics. The VISA (Visible-Infrared SASE Amplifier) program has achieved saturation at 840 nm within a 4 m long undulator. A novel bunch compression mechanism during transport was discovered and ultimately responsible for the high peak current required to drive the FEL. Start-to-end simulations, detailing the dynamics from electron beam inception at the photocathode to the FEL radiation properties at the undulator, were successfully benchmarked to observable data. The VISA II experiment is an extension of this SASE FEL operating under different experimental conditions. Driving the SASE FEL with a chirped electron beam requires maintaining the chirp throughout transport by the use of sextupole magnets to correct for second-order compression effects. The emitted radiation is frequency chirped, diagnosed via a modified frequency resolved optical gating (FROG) technique. Specific numerical simulations and diagnostic developments are presented. A set of measurements, without sextupole corrections, displays anomalous features, namely large spectral bandwidth of the radiation at stable and sustained high gain lasing. The bandwidth has an rms value of 21 nm (12% full width), previously unobserved in a FEL. In addition, the far-field angular distribution yields a hollow mode structure, similar to earlier results yet more pronounced in angle. Start-to-end simulations reproduced the

  4. Comparison between measured and simulated breakdown characteristics in micro discharges in argon

    NASA Astrophysics Data System (ADS)

    Petrovic, Zoran; Radmilovic-Radjenovic, Marija; Maguire, Paul; Mahony, Charles; Skoro, Nikola; Maric, Dragana

    2007-10-01

    Devices with micron and sub-micron gaps can face a serious challenge due to electrical breakdown during manufacturing, handling and operation. Therefore, it is necessary to be aware of the breakdown voltage for different gaps. Gas breakdown and Volt-Ampere characteristics are studied in an atmospheric pressure argon discharges. Experimental results are compared with the results obtained by using PIC/MCC code in order to establish whether the standard micro discharges operate in Townsend regime or in Glow Regime. The code is adjusted to include field emission effect in microgaps. It is applied manly for the breakdown stage but may also follow the formation of the space charge. The measurements of Volt-Ampere and breakdown characteristics of micro discharges were performed down to 20,μm gaps at pressures up to 400,orr. Paschen curves reveal that very tight geometry is required to avoid long path breakdown at the left hand side of the Paschen curve. It is critical to measure width of the discharge to test the scaling and regime of operation of micro discharges.

  5. Study of X-ray Emission from a Compact Diode Operated by a High-Inductance Capacitor Discharge

    NASA Astrophysics Data System (ADS)

    Khan, M. Z.; Ahmad, S.; Zakaullah, M.; Waheed, A.; Ahmad, R.; Murtaza, G.

    2002-12-01

    A compact diode comprising a flat plate anode and a sharp-edged cathode (a piece of razor blade) energized by 0.5 μF capacitor charged to 30 kV is investigated for optimization of X-rays emission vis-à-vis separation between electrodes and width of the cathode, which is responsible for electron emission by impact of electric field. It is a high-inductance system, the parasitic inductance is found to be 353 ± 5 nH, and the recorded peak discharge current is just 35 ± 02 kA. The maximum X-ray emission is observed for a 2-mm-wide cathode with an interelectrode separation of 3 mm. The X-ray yield in 4π-geometry is found to be 34 ± 3 mJ with a wall-plug efficiency of 0.015 ± 0.001%. The X-ray emission occurs about 200 ns after the application of high voltage, synchronized with the dip in current wave form. The low efficiency of the system for X-ray generation is attributed to high parasitic inductance.

  6. Development of an inflow controlled environmental flow regime for a Norwegian river

    NASA Astrophysics Data System (ADS)

    Alfredsen, Knut; Harby, Atle; Linnansaari, Tommi; Ugedal, Ola

    2010-05-01

    For most regulated rivers in Norway the common environmental flow regime is static and shows very little variation over the year. Recent research indicate that flow regimes that follow the natural inflow variation can meet the ecological and social demands for water in a better way. The implementation of a variable environmental flow regime provides many challenges both related to defining flow for various species and user groups in the river, but also due to practical implementation, legislation and control. A inflow controlled flow regime is developed for a Norwegian river regulated for hydro power as a pilot study. The regime should meet ecological demands from Atlantic salmon and brown trout, recreational use of water and visual impression of the river. This should be achieved preferably without altering the energy production in the hydro power system. The flow regime is developed for wet, dry and normal discharge conditions based on unregulated inflow to the catchment. The development of the seasonal flow requirements for various targets identified is done using a modification of the Building Block Method. Several options are tested regarding the integration of the flow regime into the operational strategy of the hydropower plant, both using real time prognosis of inflow and combinations with historical data. An important topic in selecting the release strategy is how it meets current Norwegian legislation and how well future documentation and environmental control can be carried out. An evaluation protocol is also proposed for the flow regime to test if the ecological targets are met.

  7. Fundamental principles of hollow-cathode-discharge operations in space and the design of a rocket-borne demonstration

    NASA Technical Reports Server (NTRS)

    Szuszczewicz, Edward P.; Mccoy, James E.; Bonifazi, Carlo; Dobrowolny, Marino

    1988-01-01

    The issue of hollow-cathode operations in space is treated from the point of view of fundamental principles of plasma interactions and their control over currents involving the device, the spaceborne vehicle, and the ambient space plasma. Particular attention is given to collective plasma processes, the effects of the ambient magnetic field, and the high probability of plasma turbulence triggered by hallow cathode operations. The paper presents a rocket payload and experiment scenario designed for accommodation on a Black Brant booster, launched from a midlatitude site to an apogee in excess of 400 km.

  8. Vaginal Discharge

    MedlinePlus

    ... also be on the lookout for symptoms of yeast infections, bacterial vaginosis and trichomoniasis, 3 infections that ... cause changes in your vaginal discharge. Signs of yeast infections White, cottage cheese-like discharge Swelling and ...

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

    SciTech Connect

    Chiper, Alina Silvia; Popa, Gheorghe

    2013-06-07

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

  10. Environmental and economic assessment of discharges from Gulf of Mexico Region Oil and Gas Operations. Quarterly technical progress report, 1 October--31 December 1993

    SciTech Connect

    Gettleson, D.A.

    1994-01-28

    Task 2 (Preparation of the Sampling and Analysis Plan) activities involved the incorporation of the offshore site selection process into the Sampling and Analysis Plan. Task 3 (Environmental Field Sampling and Analysis of NORM, Heavy Metals, and Organics) work included making decisions on tissue analyses and performing analyses of water and sediment samples. Task 4 (Monitoring of the Recovery of Impacted Wetland and Open Bay Produced Water Discharge Sites in Coastal Louisiana and Texas) activities involved the completion of the spring benthos samples collection on pre-termination samples at Four Isle Dome and the first post-termination samples at Delacroix Island. Task 5 (Assessment of Economic Impacts of Offshore and Coastal Discharge Requirements on Present and Future Operations in the Gum of Mexico Region) activities included continued work on development of a base case production forecast, modeling future production, and determining economic impact of treatment technologies. Task 6 (Synthesis of Gulf of Mexico Seafood Consumption and Use Patterns) work involved the completion of the fall survey season and the initiation of the survey data assembly. Task 7 (Technology Transfer Plan) activities included presentations at the Society of Environmental Toxicology and Chemistry annual meeting and Minerals Management Service Information Transfer Meeting. Task 8 (Project Management and Deliverables) activities involved the submission of the necessary reports and routine management.

  11. Environmental and economic assessment of discharges from Gulf of Mexico Region oil and gas operations. Quarterly technical progress report, 23 June 1992--30 September 1992

    SciTech Connect

    Gettleson, D.A.

    1992-11-10

    A Sampling and Analysis Plan was prepared and submitted to a Scientific Review Committee for comment. Substantial comments relative to study objectives, sampling design, and sampling periods coupled with the passage of Hurricane Andrew precluded the scheduled initiation of sampling at offshore and coastal sites (Tasks 3 -- Environmental Field Sampling and Analysis of Naturally Occurring Radioactive Materials (NORM), Heavy Metals, and Organics and 4 -- Monitoring of the Recovery of Impacted Wetland and Open Bay Produced Water Discharge Sites in Coastal Louisiana and Texas). A proposed revised schedule has been prepared for Tasks 3 and 4. Task 5 (Assessment of Economic Impacts of Offshore and Coastal Discharge Requirements on Present and Future Operations in the Gulf of Mexico Region), activities have involved identification and collection of the necessary data for the economic analysis. Task 6 (Synthesis of Gulf of Mexico Region Consumption and Use Patterns), activities have included near completion of the literature review and a reevaluation of the data collection efforts relative to the wholesaler, process plant, and restaurant components. Task 7 (Technology Transfer Plan), work has been delayed due to the Tasks 3 and 4 delay and cancellation of the annual US Minerals Management Service Gulf of Mexico Region Information Transfer Meeting.

  12. Periodic formation and propagation of double layers in the expanding chamber of an inductive discharge operating in Ar/SF{sub 6} mixtures

    SciTech Connect

    Plihon, N.; Corr, C.S.; Chabert, P.; Raimbault, J.-L.

    2005-07-15

    It has previously been shown [Tuszewski et al., Plasma Sources Sci. Technol. 12, 396 (2003)] that inductive discharges in electronegative gases are subject to two types of instability: the source instability related to the E to H transition and a transport instability, occurring downstream when an expanding chamber is present. These two types of instability are observed in our 'helicon' reactor operated without a static magnetic field in low-pressure Ar/SF{sub 6} mixtures. Temporally and spatially resolved measurements show that, in our experiment, the downstream instability is a periodic formation and propagation of a double layer. The double layer is born at the end of the source tube and propagates slowly to the end of the expansion region with a velocity of 150 m s{sup -1}.

  13. Reduction of the uncertainties in the water level-discharge relation of a 1D hydraulic model in the context of operational flood forecasting

    NASA Astrophysics Data System (ADS)

    Habert, J.; Ricci, S.; Le Pape, E.; Thual, O.; Piacentini, A.; Goutal, N.; Jonville, G.; Rochoux, M.

    2016-01-01

    This paper presents a data-driven hydrodynamic simulator based on the 1-D hydraulic solver dedicated to flood forecasting with lead time of an hour up to 24 h. The goal of the study is to reduce uncertainties in the hydraulic model and thus provide more reliable simulations and forecasts in real time for operational use by the national hydrometeorological flood forecasting center in France. Previous studies have shown that sequential assimilation of water level or discharge data allows to adjust the inflows to the hydraulic network resulting in a significant improvement of the discharge while leaving the water level state imperfect. Two strategies are proposed here to improve the water level-discharge relation in the model. At first, a modeling strategy consists in improving the description of the river bed geometry using topographic and bathymetric measurements. Secondly, an inverse modeling strategy proposes to locally correct friction coefficients in the river bed and the flood plain through the assimilation of in situ water level measurements. This approach is based on an Extended Kalman filter algorithm that sequentially assimilates data to infer the upstream and lateral inflows at first and then the friction coefficients. It provides a time varying correction of the hydrological boundary conditions and hydraulic parameters. The merits of both strategies are demonstrated on the Marne catchment in France for eight validation flood events and the January 2004 flood event is used as an illustrative example throughout the paper. The Nash-Sutcliffe criterion for water level is improved from 0.135 to 0.832 for a 12-h forecast lead time with the data assimilation strategy. These developments have been implemented at the SAMA SPC (local flood forecasting service in the Haute-Marne French department) and used for operational forecast since 2013. They were shown to provide an efficient tool for evaluating flood risk and to improve the flood early warning system

  14. Statistical modelling of discharge behavior of atmospheric pressure dielectric barrier discharge

    SciTech Connect

    Tay, W. H.; Kausik, S. S.; Wong, C. S. Yap, S. L.; Muniandy, S. V.

    2014-11-15

    In this work, stochastic behavior of atmospheric pressure dielectric barrier discharge (DBD) has been investigated. The experiment is performed in a DBD reactor consisting of a pair of stainless steel parallel plate electrodes powered by a 50 Hz ac high voltage source. Current pulse amplitude distributions for different space gaps and the time separation between consecutive current pulses are studied. A probability distribution function is proposed to predict the experimental distribution function for the current pulse amplitudes and the occurrence of the transition regime of the pulse distribution. Breakdown voltage at different positions on the dielectric surface is suggested to be stochastic in nature. The simulated results based on the proposed distribution function agreed well with the experimental results and able to predict the regime of transition voltage. This model would be useful for the understanding of stochastic behaviors of DBD and the design of DBD device for effective operation and applications.

  15. Evaluation of Spatial Pattern of Altered Flow Regimes on a River Network Using a Distributed Hydrological Model.

    PubMed

    Ryo, Masahiro; Iwasaki, Yuichi; Yoshimura, Chihiro; Saavedra V, Oliver C

    2015-01-01

    Alteration of the spatial variability of natural flow regimes has been less studied than that of the temporal variability, despite its ecological importance for river ecosystems. Here, we aimed to quantify the spatial patterns of flow regime alterations along a river network in the Sagami River, Japan, by estimating river discharge under natural and altered flow conditions. We used a distributed hydrological model, which simulates hydrological processes spatiotemporally, to estimate 20-year daily river discharge along the river network. Then, 33 hydrologic indices (i.e., Indicators of Hydrologic Alteration) were calculated from the simulated discharge to estimate the spatial patterns of their alterations. Some hydrologic indices were relatively well estimated such as the magnitude and timing of maximum flows, monthly median flows, and the frequency of low and high flow pulses. The accuracy was evaluated with correlation analysis (r > 0.4) and the Kolmogorov-Smirnov test (α = 0.05) by comparing these indices calculated from both observed and simulated discharge. The spatial patterns of the flow regime alterations varied depending on the hydrologic indices. For example, both the median flow in August and the frequency of high flow pulses were reduced by the maximum of approximately 70%, but these strongest alterations were detected at different locations (i.e., on the mainstream and the tributary, respectively). These results are likely caused by different operational purposes of multiple water control facilities. The results imply that the evaluation only at discharge gauges is insufficient to capture the alteration of the flow regime. Our findings clearly emphasize the importance of evaluating the spatial pattern of flow regime alteration on a river network where its discharge is affected by multiple water control facilities. PMID:26207997

  16. Evaluation of Spatial Pattern of Altered Flow Regimes on a River Network Using a Distributed Hydrological Model

    PubMed Central

    Ryo, Masahiro; Iwasaki, Yuichi; Yoshimura, Chihiro; Saavedra V., Oliver C.

    2015-01-01

    Alteration of the spatial variability of natural flow regimes has been less studied than that of the temporal variability, despite its ecological importance for river ecosystems. Here, we aimed to quantify the spatial patterns of flow regime alterations along a river network in the Sagami River, Japan, by estimating river discharge under natural and altered flow conditions. We used a distributed hydrological model, which simulates hydrological processes spatiotemporally, to estimate 20-year daily river discharge along the river network. Then, 33 hydrologic indices (i.e., Indicators of Hydrologic Alteration) were calculated from the simulated discharge to estimate the spatial patterns of their alterations. Some hydrologic indices were relatively well estimated such as the magnitude and timing of maximum flows, monthly median flows, and the frequency of low and high flow pulses. The accuracy was evaluated with correlation analysis (r > 0.4) and the Kolmogorov–Smirnov test (α = 0.05) by comparing these indices calculated from both observed and simulated discharge. The spatial patterns of the flow regime alterations varied depending on the hydrologic indices. For example, both the median flow in August and the frequency of high flow pulses were reduced by the maximum of approximately 70%, but these strongest alterations were detected at different locations (i.e., on the mainstream and the tributary, respectively). These results are likely caused by different operational purposes of multiple water control facilities. The results imply that the evaluation only at discharge gauges is insufficient to capture the alteration of the flow regime. Our findings clearly emphasize the importance of evaluating the spatial pattern of flow regime alteration on a river network where its discharge is affected by multiple water control facilities. PMID:26207997

  17. Water Quality Management With Time Varying River Flow and Discharger Control

    NASA Astrophysics Data System (ADS)

    Herbay, Jean-Pierre; Smeers, Yves; Tyteca, Daniel

    1983-12-01

    An extension of the classical river quality management problem is presented that allows for time varying operation of the treatment plants. The hydrology of the river is represented by a set of steady state flow regimes; a river water quality model is used for each of these regimes to give a constraint set to be imposed on the discharges in order to achieve the stream standards during that regime. The objective function distinguishes between investment costs, fixed operating costs, and variable operating costs. A treatment system is sought that minimizes the sum of these costs, taking account of the possibility of operating the treatment system at various different levels during the year. The model is quantified and tested on an example.

  18. Bone marrow transplant - discharge

    MedlinePlus

    Transplant - bone marrow - discharge; Stem cell transplant - discharge; Hematopoietic stem cell transplant - discharge; Reduced intensity; Non-myeloablative transplant - discharge; Mini transplant - discharge; Allogenic bone marrow transplant - ...

  19. Hip fracture - discharge

    MedlinePlus

    Inter-trochanteric fracture repair - discharge; Subtrochanteric fracture repair - discharge; Femoral neck fracture repair - discharge; Trochanteric fracture repair - discharge; Hip pinning surgery - discharge

  20. HOLLOW CARBON ARC DISCHARGE

    DOEpatents

    Luce, J.S.

    1960-10-11

    A device is described for producing an energetic, direct current, hollow, carbon-arc discharge in an evacuated container and within a strong magnetic field. Such discharges are particularly useful not only in dissociation and ionization of high energy molecular ion beams, but also in acting as a shield or barrier against the instreaming of lowenergy neutral particles into a plasma formed within the hollow discharge when it is used as a dissociating mechanism for forming the plasma. There is maintained a predetermined ratio of gas particles to carbon particles released from the arc electrodes during operation of the discharge. The carbon particles absorb some of the gas particles and are pumped along and by the discharge out of the device, with the result that smaller diffusion pumps are required than would otherwise be necessary to dispose of the excess gas.

  1. Investigation Of Plasma Discharges Within Maja-PF Device Operated With Tungsten Inserts In The Central Electrode

    SciTech Connect

    Malinowski, K.; Skladnik-Sadowska, E.; Jakubowski, L.; Sadowski, M. J.; Ladygina, M.

    2008-03-19

    The paper presents results of recent experimental studies with a MAJA-PF plasma-focus facility, as carried out for two different configurations of the end-plate of the central electrode. The main aim was to investigate an influence of the shape and material of the electrode end-plate on the formation and structure of the plasma column as well as to record and identify spectral lines of tungsten. The first version of the end-plate was made of Cu, while the second one had an insert made of a Cu-W alloy. Optical spectra were recorded by means of a Mechelle 900 spectrometer, operated with some delay in relation to a current peculiarity and with exposition times varied from 200 ns to 10 {mu}s. For shots with the Cu electrode spectral lines of deuterium (working gas) and carbon ions were recorded, but tungsten lines were not identified. It was estimated that the electron concentration changed from (8 divide 10)x10{sup 17} cm{sup -3} to about 2x10{sup 17} cm{sup -3} in 5 {mu}s after the current dip. In experiments with the second electrode version, among numerous spectral lines there were identified distinct WI and WII lines. Estimates of the tungsten ion concentration were impossible because of close positions of other lines. Diagrams of changes in the electron density are of importance for applications of DPM streams.

  2. Observation of dynamic interactions between fundamental and second-harmonic modes in a high-power sub-terahertz gyrotron operating in regimes of soft and hard self-excitation.

    PubMed

    Saito, Teruo; Tatematsu, Yoshinori; Yamaguchi, Yuusuke; Ikeuchi, Shinji; Ogasawara, Shinya; Yamada, Naoki; Ikeda, Ryosuke; Ogawa, Isamu; Idehara, Toshitaka

    2012-10-12

    Dynamic mode interaction between fundamental and second-harmonic modes has been observed in high-power sub-terahertz gyrotrons [T. Notake et al., Phys. Rev. Lett. 103, 225002 (2009); T. Saito et al. Phys. Plasmas 19, 063106 (2012)]. Interaction takes place between a parasitic fundamental or first-harmonic (FH) mode and an operating second-harmonic (SH) mode, as well as among SH modes. In particular, nonlinear excitation of the parasitic FH mode in the hard self-excitation regime with assistance of a SH mode in the soft self-excitation regime was clearly observed. Moreover, both cases of stable two-mode oscillation and oscillation of the FH mode only were observed. These observations and theoretical analyses of the dynamic behavior of the mode interaction verify the nonlinear hard self-excitation of the FH mode. PMID:23102316

  3. Angina - discharge

    MedlinePlus

    ... bypass surgery - minimally invasive - discharge Heart disease - risk factors High ... of Cardiology, Harborview Medical Center, University of Washington Medical School, Seattle, WA. Also reviewed ...

  4. INTENSE ENERGETIC GAS DISCHARGE

    DOEpatents

    Luce, J.S.

    1960-03-01

    A method and apparatus for initiating and sustaining an energetic gas arc discharge are described. A hollow cathode and a hollow anode are provided. By regulating the rate of gas flow into the interior of the cathode, the arc discharge is caused to run from the inner surface of the cathode with the result that adequate space-charge neutralization is provided inside the cathode but not in the main arc volume. Thus, the gas fed to the cathode is substantially completely ionized before it leaves the cathode, with the result that an energetic arc discharge can be maintained at lower operating pressures.

  5. Effect of the Initial Load Parameters on the K-shell Output of Al Planar Wire Arrays Operating in the Microsecond Implosion Regime

    SciTech Connect

    Shishlov, A.; Chaikovsky, S.; Fedunin, A.; Fursov, F.; Kokshenev, V.; Kurmaev, N.; Labetsky, A.; Oreshkin, V.; Rousskikh, A.; Labetskaya, N.

    2009-01-21

    A set of microsecond implosion experiments was carried on the GIT-12 generator to study the radiative performance of Al planar wire arrays. The load parameters such as a wire diameter, a gap between the wires, the number of wires, and the total planar wire mass and width were varied during the experiments, however the implosion time and the peak implosion current were almost the same for all load configurations. This ensured equal energy deposition to the plasma due to kinetic mechanisms for all load configurations. Two implosion regimes with the implosion times of 1050 ns and 850 ns were investigated. The experimental data on the K-shell radiation yield and power at varying load parameters are presented.

  6. Effect of the Initial Load Parameters on the K-shell Output of Al Planar Wire Arrays Operating in the Microsecond Implosion Regime

    NASA Astrophysics Data System (ADS)

    Shishlov, A.; Chaikovsky, S.; Fedunin, A.; Fursov, F.; Kokshenev, V.; Kurmaev, N.; Labetsky, A.; Oreshkin, V.; Rousskikh, A.; Labetskaya, N.

    2009-01-01

    A set of microsecond implosion experiments was carried on the GIT-12 generator to study the radiative performance of Al planar wire arrays. The load parameters such as a wire diameter, a gap between the wires, the number of wires, and the total planar wire mass and width were varied during the experiments, however the implosion time and the peak implosion current were almost the same for all load configurations. This ensured equal energy deposition to the plasma due to kinetic mechanisms for all load configurations. Two implosion regimes with the implosion times of 1050 ns and 850 ns were investigated. The experimental data on the K-shell radiation yield and power at varying load parameters are presented.

  7. Discharging patients.

    PubMed

    Causey, Amy

    2016-06-22

    What was the nature of the CPD activity and/or practice-related feedback and/or event or experience in your practice? The CPD article discussed the importance of effective planning when discharging patients from acute care hospitals. It emphasised the benefit of early assessment and planning, and outlined the essential principles that should be followed when discharging a patient. PMID:27332612

  8. A model for precessing helical vortex in the turbine discharge cone

    NASA Astrophysics Data System (ADS)

    Kuibin, P. A.; Susan-Resiga, R. F.; Muntean, S.

    2014-03-01

    The decelerated swirling flow in the discharge cone of hydraulic turbine develops various self-induced instabilities and associated low frequency phenomena when the turbine is operated far from the best efficiency regime. In particular, the precessing helical vortex ("vortex rope") developed at part-load regimes is notoriously difficult and expensive to be computed using full three-dimensional turbulent unsteady flow models. On the other hand, modern design and optimization techniques require robust, tractable and accurate a-priori assessment of the turbine flow unsteadiness level within a wide operating range before actually knowing the runner geometry details. This paper presents the development and validation of a quasi-analytical model of the vortex rope in the discharge cone. The first stage is the computing of the axisymmetrical swirling flow at runner outlet with input information related only to the operating point and to the blade outlet angle. Then, the swirling flow profile further downstream is computed in successive cross-sections through the discharge cone. The second stage is the reconstruction of the precessing vortex core parameters in successive cross-sections of the discharge cone. The final stage lies in assembling 3D unsteady flow field in the discharge cone. The end result is validated against both experimental and numerical data.

  9. Plasma in a Pulsed Discharge Environment

    NASA Technical Reports Server (NTRS)

    Remy, J.; Bienier, L.; Salama, F.

    2005-01-01

    The plasma generated in a pulsed slit discharge nozzle is used to form molecular ions in an astrophysically relevant environment. The plasma has been characterized as a glow discharge in the abnormal regime. Laboratory studies help understand the formation processes of polycyclic aromatic hydrocarbon (PAH) ions that are thought to be the source of the ubiquitous unidentified infrared bands.

  10. Acoustic field effects on a negative corona discharge

    NASA Astrophysics Data System (ADS)

    Bálek, R.; Červenka, M.; Pekárek, S.

    2014-06-01

    For a negative corona discharge under atmospheric pressure in different regimes, we investigated the effects of an acoustic field both on its electrical parameters and on the change in its visual appearance. We found that the application of an acoustic field on the true corona discharge, for particular currents, decreases the discharge voltage. The application of an acoustic field on the discharge in the filamentary streamer regime substantially extends the range of currents for which the discharge voltage remains more or less constant, i.e. it allows a substantial increase in the power delivered to the discharge. The application of an acoustic field on the discharge causes the discharge to spread within the discharge chamber and consequently, a highly reactive non-equilibrium plasma is created throughout the inter-electrode space. Finally, our experimental apparatus radiates almost no acoustic energy from the discharge chamber.

  11. Assessment of economic impact of offshore and coastal discharge requirements on present and future operations in the Gulf of Mexico. Final report

    SciTech Connect

    Lindsey, R.

    1996-06-01

    The high potential costs of compliance associated with new effluent guidelines for offshore and coastal oil and gas operations could significantly affect the economics of finding, developing, and producing oil and gas in the Gulf of Mexico. This report characterizes the potential economic impacts of alternative treatment and discharge regulations for produced water on reserves and production in Gulf of Mexico coastal, territorial and outer continental shelf (OCS) waters, quantifying the impacts of both recent regulatory changes and possible more stringent requirements. The treatment technologies capable of meeting these requirements are characterized in terms of cost, performance, and applicability to coastal and offshore situations. As part of this analysis, an extensive database was constructed that includes oil and gas production forecasts by field, data on existing platforms, and the current treatment methods in place for produced water treatment and disposal on offshore facilities. This work provides the first comprehensive evaluation of the impacts of alternative regulatory requirements for produced water management and disposal in coastal and offshore areas of the Gulf of Mexico.

  12. Estimating initial contaminant mass based on fitting mass-depletion functions to contaminant mass discharge data: Testing method efficacy with SVE operations data

    NASA Astrophysics Data System (ADS)

    Mainhagu, J.; Brusseau, M. L.

    2016-09-01

    The mass of contaminant present at a site, particularly in the source zones, is one of the key parameters for assessing the risk posed by contaminated sites, and for setting and evaluating remediation goals and objectives. This quantity is rarely known and is challenging to estimate accurately. This work investigated the efficacy of fitting mass-depletion functions to temporal contaminant mass discharge (CMD) data as a means of estimating initial mass. Two common mass-depletion functions, exponential and power functions, were applied to historic soil vapor extraction (SVE) CMD data collected from 11 contaminated sites for which the SVE operations are considered to be at or close to essentially complete mass removal. The functions were applied to the entire available data set for each site, as well as to the early-time data (the initial 1/3 of the data available). Additionally, a complete differential-time analysis was conducted. The latter two analyses were conducted to investigate the impact of limited data on method performance, given that the primary mode of application would be to use the method during the early stages of a remediation effort. The estimated initial masses were compared to the total masses removed for the SVE operations. The mass estimates obtained from application to the full data sets were reasonably similar to the measured masses removed for both functions (13 and 15% mean error). The use of the early-time data resulted in a minimally higher variation for the exponential function (17%) but a much higher error (51%) for the power function. These results suggest that the method can produce reasonable estimates of initial mass useful for planning and assessing remediation efforts.

  13. Estimating initial contaminant mass based on fitting mass-depletion functions to contaminant mass discharge data: Testing method efficacy with SVE operations data.

    PubMed

    Mainhagu, J; Brusseau, M L

    2016-09-01

    The mass of contaminant present at a site, particularly in the source zones, is one of the key parameters for assessing the risk posed by contaminated sites, and for setting and evaluating remediation goals and objectives. This quantity is rarely known and is challenging to estimate accurately. This work investigated the efficacy of fitting mass-depletion functions to temporal contaminant mass discharge (CMD) data as a means of estimating initial mass. Two common mass-depletion functions, exponential and power functions, were applied to historic soil vapor extraction (SVE) CMD data collected from 11 contaminated sites for which the SVE operations are considered to be at or close to essentially complete mass removal. The functions were applied to the entire available data set for each site, as well as to the early-time data (the initial 1/3 of the data available). Additionally, a complete differential-time analysis was conducted. The latter two analyses were conducted to investigate the impact of limited data on method performance, given that the primary mode of application would be to use the method during the early stages of a remediation effort. The estimated initial masses were compared to the total masses removed for the SVE operations. The mass estimates obtained from application to the full data sets were reasonably similar to the measured masses removed for both functions (13 and 15% mean error). The use of the early-time data resulted in a minimally higher variation for the exponential function (17%) but a much higher error (51%) for the power function. These results suggest that the method can produce reasonable estimates of initial mass useful for planning and assessing remediation efforts. PMID:27494132

  14. Photoelectrochromism in the Retinal Protonated Schiff Base Chromophore: Photoisomerization Speed and Selectivity under a Homogeneous Electric Field at Different Operational Regimes.

    PubMed

    El-Tahawy, Mohsen M T; Nenov, Artur; Garavelli, Marco

    2016-09-13

    The spectral tunability, photoisomerization efficiency and selectivity, of the native all-trans retinal protonated Shiff base (PSB) chromophore driven by a homogeneous electric field is systematically investigated. By analyzing the absorption wavelength dependence, charge distribution, and PES profiles along selected torsional angles, as well as the electronic structure, energetics, and topography of the CI seam in the presence of strong positive and negative electric fields, we recognize the existence of qualitatively/fundamentally different photophysics and photochemistry with respect to the unperturbed (i.e., absence of an electric field) chromophore. We rationalize the findings within the scope of molecular orbital theory and deliver a unified picture of the photophysics of the retinal PSB chromophore over a wide, even beyond the usually observed, spectral regime, ranging from the near-infrared to the ultraviolet absorption energies. This work has a 3-fold impact: a) it accounts for, and extends, previous theoretical studies on the subject; b) it delivers a rationale for the ES lifetimes observed in retinal proteins, both archeal and visual rhodopsins, as well as in solvent; and c) the transferability of the discovered trends on PSB mimics is demonstrated. PMID:27494352

  15. Yield stress reversibility and the operation of Frank-Read sources in L1{sub 2} alloys in the anomalous regime for (111) slip

    SciTech Connect

    Ezz, S.S.; Hirsch, P.B.

    1995-08-01

    The yield stress {tau}{sub y} at small strains ({approx} 0.01%) is strain rate independent, and has the same anomalous temperature dependence as that of the 0.2% strain. {tau}{sub y} is considered to be the stress at which Frank-Read sources operate in a virgin crystal. For successful operation, {tau}{sub y} must exceed the stress {tau}{sub s}, at which screws propagate dynamically through the crystal and the source dislocation must pass rapidly through the unstable Frank-Read configuration. This can be achieved by the bowing edge dislocation overcoming local obstacles before reaching that configuration. Loops elongated along the screw direction are expected to be formed in the microstrain region. Under certain conditions such loops are unstable on unloading, thereby generating long edge dislocations which can operate successfully as sources at low but not at high temperatures, explaining the reversibility phenomenon.

  16. Charge regimes for valve-regulated lead-acid batteries: Performance overview inclusive of temperature compensation

    NASA Astrophysics Data System (ADS)

    Wong, Y. S.; Hurley, W. G.; Wölfle, W. H.

    The main battery type employed in standby applications is the valve-regulated lead-acid (VRLA) battery. Float charging is normally used to maintain the battery in its fully charged state, however, float charging has limitations that can damage the battery and shorten its life. New charge regimes have evolved in recent years to tackle the intrinsic problems of float charging. The intermittent charge (IC) regime and the interrupted charge control (ICC) regime have been developed to prolong the service life of the battery in standby applications. The battery is normally maintained in the standby mode for a long period of time and there are infrequent discharge tests to verify the efficacy of the battery. Hence, the service life of the battery is highly correlated to its charge regime. This paper reviews the charge regimes for VRLA batteries, and assesses their charging performance and their impact on the service life of the battery. Recognising that temperature plays a significant role in battery operation, temperature compensation schemes are described for different charge regimes.

  17. [Nipple discharge].

    PubMed

    Deodato, G; Consoli, A; Riggi, M; Longo, G; Finocchiaro, G B

    1981-02-01

    The Authors examine the various types of breast discharge concentrating in particular on the secretions due to inherent pathology. After having studied origin, they concentrate on the diagnostic significance and the limits of exfoliative cytology and contrast mammography. The Authors conclude by presenting an original protocol of treatment of the afflicted breast illustrating in addition, the various surgical techniques proposed for the cure of the sicknesses of intramammary origin that cause abnormal discharge. PMID:7261200

  18. Post-Closure Monitoring Report for Corrective Action Unit 339: Area 12 Fleet Operations Steam Cleaning Discharge Area Nevada Test Site, Nevada

    SciTech Connect

    A. T. Urbon

    2001-08-01

    The Area 12 Fleet Operations Steam Cleaning site is located in the southeast portion of the Area 12 Camp at the Nevada Test Site (Figure 1). This site is identified in the Federal Facility Agreement and Consent Order (FFACO, 1996) as Corrective Action Site (CAS) 12-19-01 and is the only CAS assigned to Corrective Action Unit (CAU) 339. Post-closure sampling and inspection of the site were completed on March 23, 2001. Because of questionable representativeness and precision of the results, the site was resampled on June 12, 2001. Post-closure monitoring activities were scheduled biennially (every two years) in the Post-Closure Monitoring Plan provided in the December 1997 Closure Report for CAU 339: Area 12 Fleet Operations Steam Cleaning Discharge Area, Nevada Test Site (U.S. Department of Energy, Nevada Operations Office [DOE/NV], 1997). If after six years the rate of degradation appears to be so slow that the greatest concentration of total petroleum hydrocarbons (TPH) present at the site would not decay within 30 years of the site closure, the site will be reevaluated with consideration to enriching the impacted soil at the site to enhance the degradation process. A baseline for the site was established by sampling in 1997. Based on the recommendations from the 1999 post-closure monitoring report, samples were collected in 2000, earlier than originally proposed, because the 1999 sample results did not provide the expected decrease in TPH concentrations at the site. Sampling results from 2000 revealed favorable conditions for natural degradation at the CAU 339 site, but because of differing sample methods and heterogeneity of the soil, the data results from 2000 were not directly correlated with previous results. Post-closure monitoring activities for 2001 consisted of the following: Soil sample collection from three undisturbed plots (Plots A, B, and C, Figure 2); Sample analysis for TPH as oil and bio-characterization parameters (Comparative Enumeration Assay

  19. Merging of Rhine flow regimes

    NASA Astrophysics Data System (ADS)

    Boessenkool, Berry; Bronstert, Axel; Bürger, Gerd

    2016-04-01

    The Rhine flow regime is changing: (a) in the alpine nival regime, snow melt floods occur earlier in the year and (b) in the pluvial middle-Rhine regime, rainfall induced flood magnitudes rise. The seasonality of each is currently separated in time, but it is conceivable that this may shift due to climate change. If extremes of both flood types coincide, this would create a new type of hydrologic extreme with disastrous consequences. Quantifying the probability for a future overlap of pluvial and nival floods is therefore of high relevance to society and particularly to reinsurance companies. In order to investigate possible changes in magnitude and timing of flood types, we are developing a chain of physical models for spatio-temporal combination of flood probabilities. As input, we aim to use stochastically downscaled temperature and rainfall extremes from climate model weather projections. Preliminary research shows a six-week forward-shift of peak discharge at the nival gauge Maxau in the past century. The aim of presenting our early-stage work as a poster is to induce an exchange of ideas with fellow scientists in close research disciplines.

  20. 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

  1. Diverging ion motion in an inertial electrostatic confinement discharge

    SciTech Connect

    Shrier, O.; Khachan, J.; Bosi, S.; Fitzgerald, M.; Evans, N.

    2006-01-15

    An inertial electrostatic confinement device operating in the gaseous discharge pressure regime (units to tens of mTorr) is shown to consist of a substantial flux of neutrals diverging from the cathode center. Using Doppler shift spectroscopy, it is shown that directional ion beams, originating from the center, increase in energy as they move away from the center. Moreover, through charge exchange, these ions become energetic neutrals and travel out of the cathode to the anode. Although naturally there are converging ions, it is shown that this is a lesser component of the energetic particle beams in this pressure range.

  2. On unstable periodic regime of small HAWT

    NASA Astrophysics Data System (ADS)

    Dosaev, Marat Z.; Klimina, Liubov A.; Selyutskiy, Yury D.; Tsai, Mi-Ching; Yang, Hong-Tzer

    2012-11-01

    Dynamics of a small HAWT is studied. The closed mathematical model involving phenomenological description of both aerodynamic load upon turbine blades and permanent magnet electric generator is developed, in order to take into account the inductive reactance of the electric circuit. A series of experiments is performed in the subsonic wind tunnel of the LMSU Institute of Mechanics that allowed verifying the model and identifying its parameters. Parameters of dynamic model are identified, such as the coefficient of electromechanical interaction, the active internal resistance of generator, the circuit reactance. Parametric analysis of steady regimes is performed. The model prediction that HAWT operating dynamic system has two stable steady regimes (high speed regime and low speed one) is confirmed by experiments. Transient regimes are registered depending on parameters of the system, which allows estimating the unstable steady regime. The characteristics of the unstable regime are experimentally determined. Obtained results are used for estimation of aerodynamic moment acting on HAWT blades.

  3. Discharge and photo-luminance properties of a parallel plates electron emission lighting device.

    PubMed

    Li, Chia-Hung; Liu, Ming-Chung; Chiang, Chang-Lin; Li, Jung-Yu; Chen, Shih-Pu; Hsieh, Tai-Chiung; Chou, Yen-I; Lin, Yi-Ping; Wang, Po-Hung; Chun, Ming-Shin; Zeng, Hui-Kai; Juang, Jenh-Yih

    2011-01-01

    The gas discharge and photo-luminance properties of a planar lighting source featuring highly uniform light emission and mercury-free design were studied. The current density-voltage characteristics and the associated gas discharge of the devices operating with the values of the ratio of electric field to gas pressure (E/p) between 4.3 kV/Torr-cm and 35.7 kV/Torr-cm indicate that the width of the cathode fall extends over the entire gap between the two electrodes and the device is mostly in the obstructed discharge regime. The optical emission analysis confirmed the electron collision-induced gas emissions and strong effect of gas pressure on the phosphor emission when operated at constant current density, both are indicative of the primary roles played by the electron energy. PMID:21263712

  4. Effective discharge analysis of ecological processes in streams

    USGS Publications Warehouse

    Doyle, M.W.; Stanley, E.H.; Strayer, D.L.; Jacobson, R.B.; Schmidt, J.C.

    2005-01-01

    [1] Discharge is a master variable that controls many processes in stream ecosystems. However, there is uncertainty of which discharges are most important for driving particular ecological processes and thus how flow regime may influence entire stream ecosystems. Here the analytical method of effective discharge from fluvial geomorphology is used to analyze the interaction between frequency and magnitude of discharge events that drive organic matter transport, algal growth, nutrient retention, macroinvertebrate disturbance, and habitat availability. We quantify the ecological effective discharge using a synthesis of previously published studies and modeling from a range of study sites. An analytical expression is then developed for a particular case of ecological effective discharge and is used to explore how effective discharge varies within variable hydrologic regimes. Our results suggest that a range of discharges is important for different ecological processes in an individual stream. Discharges are not equally important; instead, effective discharge values exist that correspond to near modal flows and moderate floods for the variable sets examined. We suggest four types of ecological response to discharge variability: discharge as a transport mechanism, regulator of habitat, process modulator, and disturbance. Effective discharge analysis will perform well when there is a unique, essentially instantaneous relationship between discharge and an ecological process and poorly when effects of discharge are delayed or confounded by legacy effects. Despite some limitations the conceptual and analytical utility of the effective discharge analysis allows exploring general questions about how hydrologic variability influences various ecological processes in streams. Copyright 2005 by the American Geophysical Union.

  5. Simulation of non-Gaussian optical pulse propagation over piece-wise regular fiber optic link with conventional laser-optimized multimode fiber operating in a few-mode regime

    NASA Astrophysics Data System (ADS)

    Bourdine, Anton V.

    2016-03-01

    This work presents results of simulation of non-Gaussian pulse propagation over fiber optic link with irregular weakly guiding silica graded-index laser-optimized multimode optical fiber (OM2+/OM3 Cat.) operating in a few-mode regime. Here recently proposed model of irregular few-mode fiber optic link been introduced in the previous works was applied, which is based on split-step method approach combined with piece-wise regular representation. Model takes into account launch conditions, differential mode delay, both lower- and higher-order mode chromatic dispersion, differential mode attenuation, mode mixing and power diffusion occurring due to real fiber irregularity and micro-/macro-bends. Parabolic and triangular as well as Gaussian and hyperbolic secant shape laser-excited optical pulse propagation over conventional silica laser-optimized multimode fibers was simulated and researched. Some results of pulse dynamics comparison analysis are represented.

  6. Shoulder surgery - discharge

    MedlinePlus

    SLAP repair - discharge; Acromioplasty - discharge; Bankart - discharge; Shoulder repair - discharge; Shoulder arthroscopy - discharge ... You had shoulder surgery to repair the tissues inside or around your shoulder joint. The surgeon may have used a tiny ...

  7. Total colectomy or proctocolectomy - discharge

    MedlinePlus

    ... colectomy or proctolectomy -discharge; Restorative proctocolectomy - discharge; Ileal-anal resection - discharge; Ileal-anal pouch - discharge; J-pouch - discharge; S-pouch - discharge; Pelvic ...

  8. BABE - a brush cathode discharge for thermal fluctuation measurements

    NASA Astrophysics Data System (ADS)

    Ratynskaia, S.; Dilecce, G.; Tolias, P.

    2015-04-01

    For experimental tests of fluctuation theory in ideal plasmas and plasmas seeded with dust, the ideal environment would be that of stable quiescent plasma. In most laboratory plasmas the homogeneous state of the positive column is often unstable, rare exceptions are the so-called brush cathode discharges, proposed in the 60s, where a specially manufactured cathode allows stable operation in the abnormal glow regime and the only fluctuations present are those due the thermal motion of the particles. Such a device, the BAri Brush Electrode (BABE), has recently been built in a novel configuration that combines the advantages of the inverse design with those of the reflex geometry. The region between the two anodes is essentially field-free and extremely stable in wide range of plasma densities and collisionalities. Unprecedented low fluctuation levels of δn/n <= 10-5 in He and δn/n <= 5 × 10-6 in Ar discharges have been achieved.

  9. Addendum to the Closure Report for Corrective Action Unit 339: Area 12 Fleet Operations Steam Cleaning Discharge Area, Nevada Test Site, Revision 0

    SciTech Connect

    Grant Evenson

    2009-05-01

    This document constitutes an addendum to the Closure Report for CAU 339: Area 12 Fleet Operations Steam Cleaning Discharge Area Nevada Test Site, December 1997 as described in the document Supplemental Investigation Report for FFACO Use Restrictions, Nevada Test Site, Nevada (SIR) dated November 2008. The SIR document was approved by NDEP on December 5, 2008. The approval of the SIR document constituted approval of each of the recommended UR removals. In conformance with the SIR document, this addendum consists of: • This page that refers the reader to the SIR document for additional information • The cover, title, and signature pages of the SIR document • The NDEP approval letter • The corresponding section of the SIR document This addendum provides the documentation justifying the cancellation of the UR for CAS 12-19-01, A12 Fleet Ops Steam Cleaning Efflu. This UR was established as part of a Federal Facility Agreement and Consent Order (FFACO) corrective action and is based on the presence of contaminants at concentrations greater than the action levels established at the time of the initial investigation (FFACO, 1996). Since this UR was established, practices and procedures relating to the implementation of risk-based corrective actions (RBCA) have changed. Therefore, this UR was reevaluated against the current RBCA criteria as defined in the Industrial Sites Project Establishment of Final Action Levels (NNSA/NSO, 2006). This re-evaluation consisted of comparing the original data (used to define the need for the UR) to risk-based final action levels (FALs) developed using the current Industrial Sites RBCA process. The re-evaluation resulted in a recommendation to remove the UR because contamination is not present at the site above the risk-based FALs. Requirements for inspecting and maintaining this UR will be canceled, and the postings and signage at this site will be removed. Fencing and posting may be present at this site that are unrelated to the

  10. Operations

    ERIC Educational Resources Information Center

    Wilkins, Jesse L. M.; Norton, Anderson; Boyce, Steven J.

    2013-01-01

    Previous research has documented schemes and operations that undergird students' understanding of fractions. This prior research was based, in large part, on small-group teaching experiments. However, written assessments are needed in order for teachers and researchers to assess students' ways of operating on a whole-class scale. In this…

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

    NASA Astrophysics Data System (ADS)

    Ben Gadri, Rami

    1997-11-01

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

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

    EPA Science Inventory

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

  13. The effect of the operation modes of a gas discharge low-pressure amalgam lamp on the intensity of generation of 185 nm UV vacuum radiation

    SciTech Connect

    Vasilyak, L. M.; Drozdov, L. A. Kostyuchenko, S. V.; Sokolov, D. V.; Kudryavtsev, N. N.; Sobur, D. A.

    2011-12-15

    The effect of the discharge current, mercury vapor pressure, and the inert gas pressure on the intensity and efficiency of the 185 nm line generation are considered. The spectra of the UV radiation (vacuum ultraviolet) transmission by protective coatings from the oxides of rare earth metals and aluminum are investigated.

  14. Delayed discharge.

    PubMed

    Allen, Daniel

    2016-07-01

    Essential facts Delays in discharging older peo ple from hospital cost the NHS £820 million a year, according to a report from the National Audit Office (NAO). Last year in acute hospitals, 1.15 million bed days were lost to delayed transfers of care, an increase of 31% since 2013. The NAO says rising demand for NHS services is compounded by reduced local authority spending on adult social care - down by 10% since 2009-10. PMID:27380673

  15. Hysterectomy - vaginal - discharge

    MedlinePlus

    Vaginal hysterectomy - discharge; Laparoscopically assisted vaginal hysterectomy - discharge; LAVH - discharge ... you were in the hospital, you had a vaginal hysterectomy. Your surgeon made a cut in your ...

  16. Hysterectomy - vaginal - discharge

    MedlinePlus

    Vaginal hysterectomy - discharge; Laparoscopically assisted vaginal hysterectomy - discharge; LAVH - discharge ... were in the hospital, you had a vaginal hysterectomy. Your surgeon made a cut in your vagina. ...

  17. Regime shifts in the anthropocene: drivers, risks, and resilience.

    PubMed

    Rocha, Juan Carlos; Peterson, Garry D; Biggs, Reinette

    2015-01-01

    Many ecosystems can experience regime shifts: surprising, large and persistent changes in the function and structure of ecosystems. Assessing whether continued global change will lead to further regime shifts, or has the potential to trigger cascading regime shifts has been a central question in global change policy. Addressing this issue has, however, been hampered by the focus of regime shift research on specific cases and types of regime shifts. To systematically assess the global risk of regime shifts we conducted a comparative analysis of 25 generic types of regime shifts across marine, terrestrial and polar systems; identifying their drivers, and impacts on ecosystem services. Our results show that the drivers of regime shifts are diverse and co-occur strongly, which suggests that continued global change can be expected to synchronously increase the risk of multiple regime shifts. Furthermore, many regime shift drivers are related to climate change and food production, whose links to the continued expansion of human activities makes them difficult to limit. Because many regime shifts can amplify the drivers of other regime shifts, continued global change can also be expected to increase the risk of cascading regime shifts. Nevertheless, the variety of scales at which regime shift drivers operate provides opportunities for reducing the risk of many types of regime shifts by addressing local or regional drivers, even in the absence of rapid reduction of global drivers. PMID:26267896

  18. Regime Shifts in the Anthropocene: Drivers, Risks, and Resilience

    PubMed Central

    Rocha, Juan Carlos; Peterson, Garry D.; Biggs, Reinette

    2015-01-01

    Many ecosystems can experience regime shifts: surprising, large and persistent changes in the function and structure of ecosystems. Assessing whether continued global change will lead to further regime shifts, or has the potential to trigger cascading regime shifts has been a central question in global change policy. Addressing this issue has, however, been hampered by the focus of regime shift research on specific cases and types of regime shifts. To systematically assess the global risk of regime shifts we conducted a comparative analysis of 25 generic types of regime shifts across marine, terrestrial and polar systems; identifying their drivers, and impacts on ecosystem services. Our results show that the drivers of regime shifts are diverse and co-occur strongly, which suggests that continued global change can be expected to synchronously increase the risk of multiple regime shifts. Furthermore, many regime shift drivers are related to climate change and food production, whose links to the continued expansion of human activities makes them difficult to limit. Because many regime shifts can amplify the drivers of other regime shifts, continued global change can also be expected to increase the risk of cascading regime shifts. Nevertheless, the variety of scales at which regime shift drivers operate provides opportunities for reducing the risk of many types of regime shifts by addressing local or regional drivers, even in the absence of rapid reduction of global drivers. PMID:26267896

  19. Multi-stress factor model for cycle lifetime prediction of lithium ion batteries with shallow-depth discharge

    NASA Astrophysics Data System (ADS)

    Cui, Yingzhi; Du, Chunyu; Yin, Geping; Gao, Yunzhi; Zhang, Lingling; Guan, Ting; Yang, Lijie; Wang, Fuping

    2015-04-01

    Accurate prediction of service life is a major challenge for the reliable application of lithium ion batteries in satellite and electric vehicle fields. This paper carries out systematic orthogonal experiments to extract key stress factor of capacity loss for commercial LiCoO2/MCMB (mesocarbon microbeads) lithium ion batteries cycled in shallow-depth discharge. Further, single stress factor and multi-stress factor models consisting of temperature, discharge rate, taper voltage and depth of discharge for cycle life prediction of lithium ion batteries are developed. The physicochemical significance of the life prediction model is interpreted by electrochemical analysis. The practical applicability of the models is validated by experimental data. Our multi-stress factor model is helpful to predicting the lifetime of LIBs with shallow-depth discharge, and to optimizing the operation regime of LIBs for electric vehicle or satellite use.

  20. Stage-Discharge Relations for the Colorado River in Glen, Marble, and Grand Canyons, Arizona, 1990-2005

    USGS Publications Warehouse

    Hazel, Joseph E., Jr.; Kaplinski, Matt; Parnell, Rod; Kohl, Keith; Topping, David J.

    2007-01-01

    This report presents stage-discharge relations for 47 discrete locations along the Colorado River, downstream from Glen Canyon Dam. Predicting the river stage that results from changes in flow regime is important for many studies investigating the effects of dam operations on resources in and along the Colorado River. The empirically based stage-discharge relations were developed from water-surface elevation data surveyed at known discharges at all 47 locations. The rating curves accurately predict stage at each location for discharges between 141 cubic meters per second and 1,274 cubic meters per second. The coefficient of determination (R2) of the fit to the data ranged from 0.993 to 1.00. Given the various contributing errors to the method, a conservative error estimate of ?0.05 m was assigned to the rating curves.

  1. Off-axis Neutral Beam Injection as a Tool for Expanding the Operating Space of DIII-D High fNI Discharges

    NASA Astrophysics Data System (ADS)

    Ferron, J. R.; Luce, T. C.; Politzer, P. A.; Deboo, J. C.; La Haye, R. J.; Holcomb, C. T.; Lanctot, M. J.; Turco, F.; Park, J. M.; in, Y.; Okabayashi, M.

    2011-10-01

    The newly installed capability for 5 MW off-axis neutral beam injection is being utilized to broaden the pressure and current density profiles and raise the minimum q value in DIII-D discharges with noninductive current fraction fNI near 1. Broader pressure is expected to allow stable access to increased βN and increase the bootstrap current density JBS off-axis. Reducing the on-axis current drive allows access to higher qmin, increasing the on-axis JBS and improving tearing mode stability. This is a path toward DIII-D (and a steady-state powerplant) fNI = 1 discharges at q95 = 5 , which require βN >= 4 . Initial experiments have demonstrated qmin maintained above 2 with broader pressure profiles than previously observed. Analysis of the noninductive current profiles and high βN stability of discharges with off-axis beam injection will be presented. Work supported in part by US DOE under DE-FC02-04ER54698, DE-AC52-07NA27344, DE-AC05-06OR23100, DE-AC05-00OR22725, DE-FG02-08ER85195, DE-AC02-09CH11466.

  2. Energetic Ion Beam Production by a Low-Pressure Plasma Focus Discharge

    SciTech Connect

    Lim, L. K.; Yap, S. L.; Wong, C. S.

    2011-03-30

    Energetic ion beam emissions in a 3 kJ Mather type plasma focus operating at low-pressure regime are investigated. Deuterium gas is used and the discharge is operated in a low-pressure regime of below 1 mbar. Formation of the current sheath during the breakdown phase at the back wall is assisted by a set delayed trigger pulse. Energetic and intense ion beams with good reproducibility have been obtained for the operating pressure ranging from 0.05 mbar to 0.5 mbar. Deuteron beam is determined by time resolved measurement by making use of three biased ion collectors placed at the end on direction. The average energies of deuteron beams are resolved by using time-of flight method. Correlation between the ion emissions and the current sheath dynamics is also discussed.

  3. Maintenance-free, deep-discharge, lead-acid battery for photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Szymborski, J.

    1982-04-01

    Progress in the development, design, fabrication, and testing of totally maintenance-free sealed lead-acid batteries suitable for the deep-discharge regimes of solar photovoltaic applications is reported. The 6-volt, 100-ampere-hour battery was designed to meet these additional key design goals: 6-h nominal discharge rates; 80% depth-of-discharge daily duty cycle; 2000 cycles to an 80% depth-of-discharge; recharge in less than 8 h; 80% roundtrip energy efficiency; and self-discharge rate of less than 1% per week. Totally maintenance-free sealed operation was achieved by designing the cells so that only oxygen is generated on charge. The cells in this battery are fabricated with positive grids cast from a low antimony alloy in order to achieve both maintenance-free operation and good deep cycle performance. Various cycle life tests and tests to determine the tolerance of the battery to operation and storage at various states-of-charge and over a wide range of temperatures were performed. The charging parameters to adequately recharge the battery while minimizing overcharge and gassing were extensively studied.

  4. Pediatric heart surgery - discharge

    MedlinePlus

    ... discharge; Heart valve surgery - children - discharge; Heart surgery - pediatric - discharge; Heart transplant - pediatric - discharge ... Keane JF, Lock JE, Fyler DC, eds. Nadas' Pediatric Cardiology . 2nd ed. St. Louis, MO; WB Saunders; ...

  5. Heart attack - discharge

    MedlinePlus

    Myocardial infarction - discharge; MI - discharge; Coronary event - discharge; Infarct - discharge ... of patients with unstable angina/non-ST-Elevation myocardial infarction: a report of the American College of Cardiology/ ...

  6. Gastroesophageal reflux - discharge

    MedlinePlus

    Peptic esophagitis - discharge; Reflux esophagitis - discharge; GERD - discharge; Heartburn - chronic - discharge ... You have gastroesophageal reflux disease (GERD). This is a condition in which food or liquid travels backwards from the stomach to the ...

  7. Refractive corneal surgery - discharge

    MedlinePlus

    Nearsightedness surgery - discharge; Refractive surgery - discharge; LASIK - discharge; PRK - discharge ... You had refractive corneal surgery to help improve your vision. This surgery uses a laser to reshape your cornea. It corrects ...

  8. Tubal ligation - discharge

    MedlinePlus

    Sterilization surgery - female - discharge; Tubal sterilization - discharge; Tube tying - discharge; Tying the tubes - discharge ... You had tubal ligation (or tying the tubes) surgery to close your fallopian tubes. These tubes connect the ovaries to the uterus. ...

  9. Effect of gas heating on the generation of an ultrashort avalanche electron beam in the pulse-periodic regime

    NASA Astrophysics Data System (ADS)

    Baksht, E. Kh.; Burachenko, A. G.; Lomaev, M. I.; Sorokin, D. A.; Tarasenko, V. F.

    2015-07-01

    The generation of an ultrashort avalanche electron beam (UAEB) in nitrogen in the pulse-periodic regime is investigated. The gas temperature in the discharge gap of the atmospheric-pressure nitrogen is measured from the intensity distribution of unresolved rotational transitions ( C 3Π u , v' = 0) → ( B 3Π g , v″ = 0) in the nitrogen molecule for an excitation pulse repetition rate of 2 kHz. It is shown that an increase in the UAEB current amplitude in the pulse-periodic regime is due to gas heating by a series of previous pulses, which leads to an increase in the reduced electric field strength as a result of a decrease in the gas density in the zone of the discharge formation. It is found that in the pulse-periodic regime and the formation of the diffuse discharge, the number of electrons in the beam increases by several times for a nitrogen pressure of 9 × 103 Pa. The dependences of the number of electrons in the UAEB on the time of operation of the generator are considered.

  10. Laboratory experiment on boundaries of upper stage plane bed regime

    NASA Astrophysics Data System (ADS)

    Zrostlík, Štěpán; Matoušek, Václav

    2016-04-01

    Results are discussed of laboratory experiments on criteria determining the transition between the regime of dunes and the upper stage plane bed (UPB) regime and the transition between the UPB regime and the regime of wavy flow. The experiments were carried for 3 fractions of plastic material and two fractions of glass beads in a broad range of flow conditions (different discharges of water and solids and longitudinal bed slopes) in a tilting flume. The experiments reveal that, contrary to expectations, a constant value of the Shields parameter is not an appropriate criterion for the transition between the dune regime and the UPB regime. Furthermore, the transition appears to be insensitive to the total discharge of solids and water. Instead, the criterion seems to be well represented by a constant value of the average transport concentration of sediment (the ratio of volumetric discharge of solids and volumetric discharge of mixture). The experimental results exhibit a very tight correlation between the transport concentration and the longitudinal bed slope. Hence, a constant value of the bed slope can be considered an appropriate criterion for the transition. The transition between the UPB regime and the wavy regime (significant waves develop but they are not always standing waves) is found at a constant value of Froude number, which is in agreement with literature, although it is found at a higher value than the literature usually suggests (Fr = 1.2 instead of 1.0). Hence, the transition occurs in the super-critical flow but it is not necessarily associated with the critical flow.

  11. Ireland unveils new license regime

    SciTech Connect

    Not Available

    1992-11-23

    Ireland has unveiled new terns designed to integrate the licensing regime for oil and gas exploration and development. They apply to new exploration and development authorizations and replace the exclusive offshore licensing terns introduced in 1975. Holders of existing licenses are still subject to the 1975 terms but can choose the new terns under appropriate circumstances. Frontier exploration licenses are currently available to complement the standard and deepwater exploration licenses in use. Rental fees are now spread evenly over the duration of the license, thereby eliminating large upfront payments. Lease extensions also have been introduced to enable operators to judge commerciality of a discovery beyond the set license period.

  12. Synthesis and investigation of reaction mechanisms of diamondoids obtained by dielectric barrier discharge microplasma reactors operated in adamantane - argon - methane - hydrogen mixtures at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Stauss, Sven; Ishii, Chikako; Pai, David Z.; Terashima, Kazuo

    2013-09-01

    Diamondoids, sp3 hybridized molecules consisting of a cage-like carbon framework with hydrogen terminations, hold promise for many applications: biotechnology, medicine, and opto- and nanoelectronics. So far, diamondoids consisting of more than four cage units have been synthesized by electric discharge and pulsed laser plasmas in supercritical fluids, but the generation of plasmas in high-pressure media is not straightforward. Here we present an alternative, continuous flow process, where diamondoids are synthesized by dielectric barrier discharges inside microreactors. The plasmas were generated at peak-to-peak voltages of 3 - 4 kV at a frequency of 10 kHz, in Ar (96 - 100%-vol) - methane (0 - 4%-vol) - hydrogen (0 - 4%-vol) mixtures, at atmospheric pressure and flow rates of 2 - 20 sccm. As a precursor we used the first diamondoid, adamantane, whose density was controlled by adjusting the reactor temperature in the range from 293 to 323 K. Gas chromatography - mass spectrometry analysis indicated the synthesis of the second diamondoid, diamantane, and the presence of alkylated adamantane derivatives suggests a stepwise reaction mechanism. We will also discuss the influence of the plasma gas composition and precursor density on the diamondoid synthesis. Grant No. 21110002, MEXT, Japan.

  13. Arctic circulation regimes.

    PubMed

    Proshutinsky, Andrey; Dukhovskoy, Dmitry; Timmermans, Mary-Louise; Krishfield, Richard; Bamber, Jonathan L

    2015-10-13

    Between 1948 and 1996, mean annual environmental parameters in the Arctic experienced a well-pronounced decadal variability with two basic circulation patterns: cyclonic and anticyclonic alternating at 5 to 7 year intervals. During cyclonic regimes, low sea-level atmospheric pressure (SLP) dominated over the Arctic Ocean driving sea ice and the upper ocean counterclockwise; the Arctic atmosphere was relatively warm and humid, and freshwater flux from the Arctic Ocean towards the subarctic seas was intensified. By contrast, during anticylonic circulation regimes, high SLP dominated driving sea ice and the upper ocean clockwise. Meanwhile, the atmosphere was cold and dry and the freshwater flux from the Arctic to the subarctic seas was reduced. Since 1997, however, the Arctic system has been under the influence of an anticyclonic circulation regime (17 years) with a set of environmental parameters that are atypical for this regime. We discuss a hypothesis explaining the causes and mechanisms regulating the intensity and duration of Arctic circulation regimes, and speculate how changes in freshwater fluxes from the Arctic Ocean and Greenland impact environmental conditions and interrupt their decadal variability. PMID:26347536

  14. Arctic circulation regimes

    PubMed Central

    Proshutinsky, Andrey; Dukhovskoy, Dmitry; Timmermans, Mary-Louise; Krishfield, Richard; Bamber, Jonathan L.

    2015-01-01

    Between 1948 and 1996, mean annual environmental parameters in the Arctic experienced a well-pronounced decadal variability with two basic circulation patterns: cyclonic and anticyclonic alternating at 5 to 7 year intervals. During cyclonic regimes, low sea-level atmospheric pressure (SLP) dominated over the Arctic Ocean driving sea ice and the upper ocean counterclockwise; the Arctic atmosphere was relatively warm and humid, and freshwater flux from the Arctic Ocean towards the subarctic seas was intensified. By contrast, during anticylonic circulation regimes, high SLP dominated driving sea ice and the upper ocean clockwise. Meanwhile, the atmosphere was cold and dry and the freshwater flux from the Arctic to the subarctic seas was reduced. Since 1997, however, the Arctic system has been under the influence of an anticyclonic circulation regime (17 years) with a set of environmental parameters that are atypical for this regime. We discuss a hypothesis explaining the causes and mechanisms regulating the intensity and duration of Arctic circulation regimes, and speculate how changes in freshwater fluxes from the Arctic Ocean and Greenland impact environmental conditions and interrupt their decadal variability. PMID:26347536

  15. Prediction of nested complementary pattern in argon dielectric-barrier discharge at atmospheric pressure.

    PubMed

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

    2015-01-01

    A two-dimensional self-consistent fluid model was employed to investigate the spatiotemporal nonlinear behavior in an argon glow-like/Townsend-like dielectric-barrier discharge (DBD) at atmospheric pressure. The discharge is characterized by a major current pulse with a residual one ahead per half cycle of the external voltage. The two current pulses are operated in glow mode, but with Townsend mode between them. Contrasting spatial discharge structures are complementarily presented not only at two current pulses in the same half cycle but also during the discharge in the two adjacent-half cycles, resulting in the formation of a unique nested complementary pattern each cycle. This peculiar behavior mainly lies in the fact that sufficient charged particles are trapped in the gas gap due to the last discharge and able to dominate the subsequent discharge through the "spatial memory effect". The charge transport regime reveals that this nested complementary pattern is presented only in a limited range of driving frequency. PMID:26552714

  16. Prediction of nested complementary pattern in argon dielectric-barrier discharge at atmospheric pressure

    PubMed Central

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

    2015-01-01

    A two-dimensional self-consistent fluid model was employed to investigate the spatiotemporal nonlinear behavior in an argon glow-like/Townsend-like dielectric-barrier discharge (DBD) at atmospheric pressure. The discharge is characterized by a major current pulse with a residual one ahead per half cycle of the external voltage. The two current pulses are operated in glow mode, but with Townsend mode between them. Contrasting spatial discharge structures are complementarily presented not only at two current pulses in the same half cycle but also during the discharge in the two adjacent-half cycles, resulting in the formation of a unique nested complementary pattern each cycle. This peculiar behavior mainly lies in the fact that sufficient charged particles are trapped in the gas gap due to the last discharge and able to dominate the subsequent discharge through the “spatial memory effect”. The charge transport regime reveals that this nested complementary pattern is presented only in a limited range of driving frequency. PMID:26552714

  17. In situ CF3 Detection in Low Pressure Inductive Discharges by Fourier Transform Infrared Spectroscopy

    NASA Technical Reports Server (NTRS)

    Kim, J. S.; Cappelli, M. A.; Sharma, S. P.; Arnold, J. O. (Technical Monitor)

    1998-01-01

    The detection of CF(x) (x=1-3) radicals in low pressure discharges using source gases such as CF4 and CHF3 is of importance to the understanding of their chemical structure and relevance in plasma based etching processes. These radicals are known to contribute to the formation of fluorocarbon polymer films, which affect the selectivity and anisotropy of etching. In this study, we present preliminary results of the quantitative measurement of trifluoromethyl radicals, CF3, in low pressure discharges. The discharge studied here is an inductively (transformer) coupled plasma (ICP) source in the GEC reference cell, operating on pure CF4 at pressures ranging from 10 - 100 mTorr, This plasma source generates higher electron number densities at lower operating pressures than obtainable with the parallel-plate capacitively coupled version of the GEC reference cell. Also, this expanded operating regime is more relevant to new generations of industrial plasma reactors being used by the microelectronics industry. Fourier transform infrared (FTIR) spectroscopy is employed to observe the absorption band of CF3 radicals in the electronic ground state X2Al in the region of 1233-1270/cm. The spectrometer is equipped with a high sensitivity HgCdTe (MCT) detector and has a fixed resolution of 0.125/cm. The CF3 concentrations are measured for a range of operating pressures and discharge power levels.

  18. Influence of operating parameters on surface properties of RF glow discharge oxygen plasma treated TiO₂/PET film for biomedical application.

    PubMed

    Pandiyaraj, K Navaneetha; Deshmukh, R R; Mahendiran, R; Su, Pi-G; Yassitepe, Emre; Shah, Ismat; Perni, Stefano; Prokopovich, Polina; Nadagouda, Mallikarjuna N

    2014-03-01

    In this paper, a thin transparent titania (TiO2) film was coated on the surface of flexible poly(ethylene terephthalate) (PET) film using the sol-gel method. The surface properties of the obtained TiO2/PET film were further improved by RF glow discharge oxygen plasma as a function of exposure time and discharge power. The changes in hydrophilicity of TiO2/PET films were analyzed by contact angle measurements and surface energy. The influence of plasma on the surface of the TiO2/PET films was analyzed by atomic force microscopy (AFM) as well as the change in chemical state and composition that were investigated by X-ray photo electron spectroscopy (XPS). The cytotoxicity of the TiO2/PET films was analyzed using human osteoblast cells and the bacterial eradication behaviors of TiO2/PET films were also evaluated against Staphylococcus bacteria. It was found that the surface roughness and incorporation of oxygen containing polar functional groups of the plasma treated TiO2/PET films increased substantially as compared to the untreated one. Moreover the increased concentration of Ti(3+) on the surface of plasma treated TiO2/PET films was due to the transformation of chemical states (Ti(4+)→Ti(3+)). These morphological and chemical changes are responsible for enhanced hydrophilicity of the TiO2/PET films. Furthermore, the plasma treated TiO2/PET film exhibited no citotoxicity against osteoblast cells and antibacterial activity against Staphylococcus bacteria which can find application in manufacturing of biomedical devices. PMID:24433917

  19. Simulation and Analysis of the Hybrid Operating Mode in ITER

    SciTech Connect

    Kessel, C.E.; Budny, R.V.; Indireshkumar, K.

    2005-09-22

    The hybrid operating mode in ITER is examined with 0D systems analysis, 1.5D discharge scenario simulations using TSC and TRANSP, and the ideal MHD stability is discussed. The hybrid mode has the potential to provide very long pulses and significant neutron fluence if the physics regime can be produced in ITER. This paper reports progress in establishing the physics basis and engineering limitation for the hybrid mode in ITER.

  20. Sediment regime constraints on river restoration - An example from the lower missouri river

    USGS Publications Warehouse

    Jacobson, R.B.; Blevins, D.W.; Bitner, C.J.

    2009-01-01

    Dammed rivers are subject to changes in their flow, water-quality, and sediment regimes. Each of these changes may contribute to diminished aquatic habitat quality and quantity. Of the three factors, an altered sediment regime is a particularly unyielding challenge on many dammed rivers. The magnitude of the challenge is illustrated on the Lower Missouri River, where the largest water storage system in North America has decreased the downriver suspended-sediment load to 0.2%-17% of predamloads. In response to the altered sediment regime, the Lower Missouri River channel has incised as much as 3.5 m just downstream of Gavins Point Dam, although the bed has been stable to slightly aggrading at other locations farther downstream. Effects of channel engineering and commercial dredging are superimposed on the broad-scale adjustments to the altered sediment regime. The altered sediment regime and geomorphic adjustments constrain restoration and management opportunities. Incision and aggradation limit some objectives of flow-regime management: In incising river segments, ecologically desirable reconnection of the floodplain requires discharges that are beyond operational limits, whereas in aggrading river segments, small spring pulses may inundate or saturate low-lying farmlands. Lack of sediment in the incising river segment downstream of Gavins Point Dam also limits sustainable restoration of sand-bar habitat for bird species listed under the Endangered Species Act. Creation of new shallow-water habitat for native fi shes involves taking sediment out of floodplain storage and reintroducing most or all of it to the river, raising concerns about increased sediment, nutrient, and contaminant loads. Calculations indicate that effects of individual restoration projects are small relative to background loads, but cumulative effects may depend on sequence and locations of projects. An understanding of current and historical sediment fl uxes, and how they vary along the river

  1. Climatic and landscape controls on effective discharge

    NASA Astrophysics Data System (ADS)

    Basso, S.; Frascati, A.; Marani, M.; Schirmer, M.; Botter, G.

    2015-10-01

    The effective discharge constitutes a key concept in river science and engineering. Notwithstanding many years of studies, a full understanding of the effective discharge determinants is still challenged by the variety of values identified for different river catchments. The present paper relates the observed diversity of effective discharge to the underlying heterogeneity of flow regimes. An analytic framework is proposed, which links the effective ratio (i.e., the ratio between effective discharge and mean streamflow) to the empirical exponent of the sediment rating curve and to the streamflow variability, resulting from climatic and landscape drivers. The analytic formulation predicts patterns of effective ratio versus streamflow variability observed in a set of catchments of the continental United States and helps in disentangling the major climatic and landscape drivers of sediment transport in rivers. The findings highlight larger effective ratios of erratic hydrologic regimes (characterized by high flow variability) compared to those exhibited by persistent regimes, which are attributable to intrinsically different streamflow dynamics. The framework provides support for the estimate of effective discharge in rivers belonging to diverse climatic areas.

  2. Discharge processes of UV pre-ionized electric-discharge pulsed DF laser

    NASA Astrophysics Data System (ADS)

    Pan, Qikun; Xie, Jijiang; Shao, Chunlei; Wang, Chunrui; Shao, Mingzhen; Guo, Jin

    2016-03-01

    The discharge processes of ultraviolet (UV) pre-ionized electric-discharge pulsed DF laser operating with a SF6-D2 gas mixture are studied. A mathematical model based on continuity equation of electrons and Kirchhoff equations for discharge circuit is established to describe the discharge processes. Voltage and current waveforms of main discharge and voltage waveforms of pre-ionization are solved numerically utilizing the model. The calculations correctly display some physical processes, such as the delay time between pre-ionization and main discharge, breakdown of the main electrode and self-sustained volume discharge (SSVD). The results of theory are consistent with the experiments, which are performed in our non-chain pulsed DF laser. Then the delay inductance and peak capacitance are researched to analyze their influences on discharge processes, and the circuit parameters of DF laser are given which is useful to improve the discharge stability.

  3. A Simulation of Pre-Arcing Plasma Discharge Processes in Water Purification

    SciTech Connect

    Rodriguez-Mendez, B. G.; Piedad-Beneitez, A. de la; Lopez-Callejas, R.; Godoy-Cabrera, O. G.; Benitez-Read, J. S.; Pacheco-Sotelo, J. O.; Pena-Eguiluz, R.; Mercado-Cabrera, A.; Valencia-A, R.; Barocio, S. R.

    2006-12-04

    The simulation of a water purification system within a coaxial cylinder reactor operated by 1 kHz frequency plasma discharges in pre-arcing regimes is presented. In contrast with precedent works, this computational model considers three mechanisms of the system operation: (a) the relevant physical characteristics of water (b) the ionisation and expansion processes in the spark channel including the near-breakdown electric current generated by the rate of change of the effective capacitance and resistance in the discharge, and (c) the energy associated with this initial spark in the water. The outcome of the model seems to meet all main requirements to allow the design and construction of specific water purification technology devices.

  4. Regimes of Helium Burning

    SciTech Connect

    Timmes, F. X.; Niemeyer, J. C.

    2000-07-10

    The burning regimes encountered by laminar deflagrations and Zeldovich von Neumann Doering [ZND] detonations propagating through helium-rich compositions in the presence of buoyancy-driven turbulence are analyzed. Particular attention is given to models of X-ray bursts that start with a thermonuclear runaway on the surface of a neutron star and to the thin-shell helium instability of intermediate-mass stars. In the X-ray burst case, turbulent deflagrations propagating in the lateral or radial direction encounter a transition from the distributed regime to the flamelet regime at a density of {approx}108 g cm-3. In the radial direction, the purely laminar deflagration width is larger than the pressure scale height for densities smaller than {approx}106 g cm-3. Self-sustained laminar deflagrations traveling in the radial direction cannot exist below this density. Similarly, the planar ZND detonation width becomes larger than the pressure scale height at {approx}107 g cm-3, suggesting that steady state, self-sustained detonations cannot come into existence in the radial direction. In the thin helium shell case, turbulent deflagrations traveling in the lateral or radial direction encounter the distributed regime at densities below {approx}107 g cm-3 and the flamelet regime at larger densities. In the radial direction, the purely laminar deflagration width is larger than the pressure scale height for densities smaller than {approx}104 g cm-3, indicating that steady state laminar deflagrations cannot form below this density. The planar ZND detonation width becomes larger than the pressure scale height at {approx}5x10{sup 4} g cm-3, suggesting that steady state, self-sustained detonations cannot come into existence in the radial direction. (c) 2000 The American Astronomical Society.

  5. Pulsed discharge production Ar* metastables

    NASA Astrophysics Data System (ADS)

    Han, Jiande; Heaven, Michael C.; Emmons, Daniel; Perram, Glen P.; Weeks, David E.; Bailey, William F.

    2016-03-01

    The production of relatively high densities of Ar* metastables (>1012 cm-3) in Ar/He mixtures, at total pressures close to 1 atm, is essential for the efficient operation of an optically pumped Ar* laser. We have used emission spectroscopy and diode laser absorption spectroscopy measurements to observe the production and decay of Ar* in a parallel plate pulsed discharge. With discharge pulses of 1 μs duration we find that metastable production is dominated by processes occurring within the first 100 ns of the gas break-down. Application of multiple, closely spaced discharge pulses yields insights concerning conditions that favor metastable production. This information has been combined with time-resolved measurements of voltage and current. The experimental results and preliminary modeling of the discharge kinetics are presented.

  6. Surface water discharges from onshore stripper wells.

    SciTech Connect

    Veil, J. A.

    1998-01-16

    Under current US Environmental Protection Agency (EPA) rules, small onshore oil producers are allowed to discharge produced water to surface waters with approval from state agencies; but small onshore gas producers, however, are prohibited from discharging produced water to surface waters. The purpose of this report is to identify those states that allow surface water discharges from small onshore oil operations and to summarize the types of permitting controls they use. It is intended that the findings of this report will serve as a rationale to encourage the EPA to revise its rules and to remove the prohibition on surface water discharges from small gas operations.

  7. 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

  8. Eye muscle repair - discharge

    MedlinePlus

    ... Lazy eye repair - discharge; Strabismus repair - discharge; Extraocular muscle surgery - discharge ... You or your child had eye muscle repair surgery to correct eye muscle ... term for crossed eyes is strabismus. Children most often ...

  9. Radical prostatectomy - discharge

    MedlinePlus

    ... laparoscopic prostatectomy - discharge ; RALP - discharge; Pelvic lymphadenectomy - discharge; Prostate cancer - prostatectomy ... some lymph nodes. This was done to treat prostate cancer. Your surgeon may have made an incision (cut) ...

  10. Tennis elbow surgery - discharge

    MedlinePlus

    ... epicondylitis surgery - discharge; Lateral tendinosis surgery - discharge; Lateral tennis elbow surgery - discharge ... long as you are told. This helps ensure tennis elbow will not return. You may be prescribed ...

  11. Measurement of metastable He{sup *}(2{sup 3}S{sub 1}) density in dielectric barrier discharges with two different configurations operating at around atmospheric pressure

    SciTech Connect

    Tachibana, K.; Kishimoto, Y.; Sakai, O.

    2005-06-15

    We have measured the density of metastable He atoms in the lowest triplet state (2{sup 3}S{sub 1}) with a diode-laser absorption spectroscopic technique in atmospheric pressure plasmas produced by dielectric barrier discharge schemes. Two different types of electrode configuration are employed: one is a conventional parallel-plate system and the other is a microdischarge integrated system with stacked metal-mesh electrodes covered by insulating films. We have analyzed the pressure-broadened spectral line corresponding to the 2{sup 3}S{sub 1}{yields}2{sup 3}P{sub J} (J=0-2) transition to derive the broadening coefficient and to calibrate absolute densities. The measured density ranges from 10{sup 11} to 10{sup 12} cm{sup -3}, but the values in the mesh-type system are larger than those in the parallel-plate system by about one order of magnitude. The density, however, depends strongly on the gas flow rate, showing the influence of quenching by the Penning-ionization process with impurities. Those behaviors are consistent with the variation of the electron density estimated by millimeter-wave transmittance measurement.

  12. Measurement of metastable He*(23S1) density in dielectric barrier discharges with two different configurations operating at around atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Tachibana, K.; Kishimoto, Y.; Sakai, O.

    2005-06-01

    We have measured the density of metastable He atoms in the lowest triplet state (2S13) with a diode-laser absorption spectroscopic technique in atmospheric pressure plasmas produced by dielectric barrier discharge schemes. Two different types of electrode configuration are employed: one is a conventional parallel-plate system and the other is a microdischarge integrated system with stacked metal-mesh electrodes covered by insulating films. We have analyzed the pressure-broadened spectral line corresponding to the 2S13→2PJ3 (J=0-2) transition to derive the broadening coefficient and to calibrate absolute densities. The measured density ranges from 1011 to 1012cm-3, but the values in the mesh-type system are larger than those in the parallel-plate system by about one order of magnitude. The density, however, depends strongly on the gas flow rate, showing the influence of quenching by the Penning-ionization process with impurities. Those behaviors are consistent with the variation of the electron density estimated by millimeter-wave transmittance measurement.

  13. ACL reconstruction - discharge

    MedlinePlus

    Anterior cruciate ligament reconstruction - discharge; ACL reconstruction - discharge ... had surgery to reconstruct your anterior cruciate ligament (ACL). The surgeon drilled holes in the bones of ...

  14. Dynamic Treatment Regimes

    PubMed Central

    Chakraborty, Bibhas; Murphy, Susan A.

    2014-01-01

    A dynamic treatment regime consists of a sequence of decision rules, one per stage of intervention, that dictate how to individualize treatments to patients based on evolving treatment and covariate history. These regimes are particularly useful for managing chronic disorders, and fit well into the larger paradigm of personalized medicine. They provide one way to operationalize a clinical decision support system. Statistics plays a key role in the construction of evidence-based dynamic treatment regimes – informing best study design as well as efficient estimation and valid inference. Due to the many novel methodological challenges it offers, this area has been growing in popularity among statisticians in recent years. In this article, we review the key developments in this exciting field of research. In particular, we discuss the sequential multiple assignment randomized trial designs, estimation techniques like Q-learning and marginal structural models, and several inference techniques designed to address the associated non-standard asymptotics. We reference software, whenever available. We also outline some important future directions. PMID:25401119

  15. Investigating the dependence of the temperature of high-intensity discharge (HID) lamp electrodes on the operating frequency by pyrometric measurements

    NASA Astrophysics Data System (ADS)

    Reinelt, J.; Westermeier, M.; Ruhrmann, C.; Bergner, A.; Awakowicz, P.; Mentel, J.

    2011-03-01

    Phase-resolved temperature distributions are determined along a rod-shaped tungsten electrode, by which an ac arc is operated within a model lamp filled with argon. Switched dc and sinusoidal currents are applied with amplitudes of several amperes and operating frequencies being varied between 10 Hz and 10 kHz. The temperature is deduced from the grey body radiation of the electrode being recorded with a spectroscopic measuring system. Phase-resolved values of the electrode tip temperature Ttip and of the power input Pin are determined comparing the measured temperature distributions with the integral of the one-dimensional heat balance with these parameters as integration constants. They are supplemented by phase-resolved measurements of the sum of cathode and anode fall called the electrode sheath voltage. If a switched dc current is applied it is found that both quantities are within the cathodic phase only marginally higher than for a cathode being operated with a dc current. Ttip and Pin start to decrease for low currents and to increase for high currents at the beginning of the anodic phase. But with increasing operating frequency the deviations from the cathodic phase are reduced until they cannot be resolved for frequencies of several kHz. A more pronounced modulation, but the same tendencies, is observed with a sinusoidal current waveform. For 10 kHz a diffuse arc attachment with an almost phase-independent electrode tip temperature, which deviates only marginally from that of a dc cathode, and an electrode sheath voltage proportional to the arc current is established with both current waveforms.

  16. PIC-MCC Simulations of Capacitive High-Frequency Discharge Dynamics with Nanoparticles

    NASA Astrophysics Data System (ADS)

    Schweigert, Irina V.

    A new combined particle-in-cell Monte Carlo collision (PIC-MCC) approach is discussed for accurate and fast simulation of a radio-frequency (rf) discharge at a low gas pressure and high plasma density. Test calculations of the heating mode transition in a capacitively coupled rf-discharge in helium and argon show a good agreement with experimental data. The combined PIC-MCC algorithm is very efficient, especially for the collisionless regime of electron heating. Using this algorithm, the properties of a capacitively coupled 13.56 MHz discharge are studied in a mixture of Ar/C2H2 with nanoparticles of different sizes. For the description of plasma-dust interaction a kinetic model is introduced. The dust surface potential and discharge parameters are calculated self-consistently. In this model, any assumption about electron and ion energy distribution functions is not used. This allows us to calculate accurately the dust particle charging. The transport of dust is calculated by using the fluid approach. It is shown that at the initial stage of the growth, nanoparticles are accumulated near the sheath-plasma boundaries, where the ionization rate has maximum value. The nanoparticles suppress the ionization due to the absorbing of fast electrons and stimulate a quick change of the plasma parameters followed by the transition between different modes of discharge operation.

  17. Influence of discharge and jet flow coupling on atmospheric pressure plasma homogeneity

    NASA Astrophysics Data System (ADS)

    Nizard, H.; Gaudy, T.; Toutant, A.; Iacono, J.; Descamps, P.; Leempoel, P.; Massines, F.

    2015-10-01

    The effect of flow dynamics on the discharge mode is studied in order to design a technical solution for thin film coating on large surfaces. The configuration consists in two atmospheric pressure helium plasma jets impacting a surface and confined in a tube. This system operates in open air. It has been studied by short exposure time pictures, current and voltage measurements, optical emission spectroscopy, schlieren flow visualization and computational fluid dynamics. Two discharge regimes directly connected to the gas flow dynamic have been pointed out. One is localized from the point electrodes to the surface; the other one entirely fills the confinement tube. A correlation between air intake inside the confinement tube and the discharge mode has been highlighted. Indeed, the discharge only develops in helium and the air intake confines the helium jets in volumes smaller than the confinement tube. The air intake is determined by the gas flow rate and the distance from the tube bottom to the substrate surface, parameters which have been linked to the change from laminar to turbulent flow. Finally, the understanding of flow dynamics and discharge plasma coupling allowed the design of a technical solution favoring plasma homogeneity for large surface treatment.

  18. High-pressure dc glow discharges in hollow diamond cathodes

    NASA Astrophysics Data System (ADS)

    Truscott, B. S.; Turner, C.; May, P. W.

    2016-04-01

    We report the generation and characterization of dc helium microdischarges at several times atmospheric pressure in monolithic diamond hollow-cathode devices having cavity diameters on the order of 100 μm. I-V characteristics indicated operation in the glow discharge regime even at nearly 10 atm, while spectroscopic measurements of the N2 C3Πu  →  B3Πg emission returned rotational temperatures always around 420 K, with a pressure-dependent vibrational population distribution. The variation of breakdown voltage with pressure closely followed Paschen’s law, but with offsets in both axes that we tentatively ascribe to strong diffusive loss and a partial thermalization of electron energies under the high pressures considered here.

  19. START High Performance Discharges

    NASA Astrophysics Data System (ADS)

    Gates, D. A.

    1997-11-01

    . Analysis of the confinement properties of the discharge and a discussion of the scaling of confinement with global plasma parameters will be presented. Comparisons are made between the predictions of neoclassical transport theory and ion temperature measurements from a charge exchange spectrometer. These results indicate the ability of spherical tokamaks to support high β operation with good confinement. Experiments in the MAST (Mega Amp Spherical Tokamak) device, currently under construction, will demonstrate spherical tokamak operations for significantly longer pulse lengths at high ( ~1-2MA) plasma current.

  20. Investigation of low discharge voltage Hall thruster characteristics and evaluation of loss mechanisms

    NASA Astrophysics Data System (ADS)

    Brown, Daniel Lucas

    During the early development stages of Hall thruster technology, plasma research and propulsion advancements centered primarily on 300-V, 1600-s specific impulse operation. Since the first Hall thruster firing on a Soviet satellite in 1972, extensive investigations of the plasmadynamic discharge phenomena and operating characteristics progressed the propulsion concept to a high level of performance suitable for a wide range of near-earth maneuvers and interplanetary missions. The expanded performance envelope is primarily a function of improvements in thruster lifetime, thermal margin, discharge stability, and power system capability. Advancements in Hall thruster propulsion systems enable a wider range of input parameters to the thruster, including the applied anode-to-cathode potential. Operation in the low discharge voltage regime is associated with a decline in total thruster efficiency. This dissertation is intended to investigate low-voltage Hall thruster physics, identify dominant performance loss mechanisms, and determine the discharge characteristics that drive efficiency. A systematic, experimental investigation of low-voltage Hall thruster performance and plume properties led to the conclusion that reduced electron temperature in the discharge was correlated with diminished Joule heating losses and a lower ionization cost per beam ion. However, the reduced electron temperature also decreased the ionization rate coefficient, and corresponded to an escalation of electron current to the anode to sustain ionization processes. In addition, divergence of the kinetic ion jet limited the component of axially directed thrust and reduced the total thruster efficiency. Two jet-mode Hall thruster operating regimes were discovered for low-voltage operation, corresponding to ionization instabilities in the discharge and additional electron current to the anode. These modes are methodically characterized and potential causes are hypothesized. During the course of this

  1. Progress in discharge-pumped excimer lasers

    NASA Astrophysics Data System (ADS)

    Pike, Charles T.

    1993-04-01

    This paper describes recent results achieved in the development of discharge pumped excimer lasers at the Textron Defense Systems organization (formerly the Avco Research Laboratory). Included is a description of a KrF laser with more than one Joule output at 2.4% efficiency, a 200 mJ XeCl laser operating with a 500 nsec wide pulse, and a several Joule, discharge pumped, KrCl laser operating at 222 nm. All of these devices are switched using thyratrons and are therefore capable of repetitive performance. The KrF and XeCl experiments were conducted with the same laser device operating with a conventional capacitor transfer excitation circuit for the KrF experiments but modified to operate with a pulser-sustainer discharge circuit using magnetic switching for the XeCl tests. The KrCl device is a 40 liter volume system built by Northrop and also operates with a magnetically switched discharge.

  2. GAS DISCHARGE DEVICES

    DOEpatents

    Arrol, W.J.; Jefferson, S.

    1957-08-27

    The construction of gas discharge devices where the object is to provide a gas discharge device having a high dark current and stabilized striking voltage is described. The inventors have discovered that the introduction of tritium gas into a discharge device with a subsequent electrical discharge in the device will deposit tritium on the inside of the chamber. The tritium acts to emit beta rays amd is an effective and non-hazardous way of improving the abovementioned discharge tube characteristics

  3. 33 CFR 156.125 - Discharge cleanup.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Discharge cleanup. 156.125... § 156.125 Discharge cleanup. (a) Each person conducting the transfer operation shall stop the transfer... work area; or (2) Into the water or upon the adjoining shoreline in the transfer area. (b) Except...

  4. 33 CFR 156.125 - Discharge cleanup.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Discharge cleanup. 156.125... § 156.125 Discharge cleanup. (a) Each person conducting the transfer operation shall stop the transfer... work area; or (2) Into the water or upon the adjoining shoreline in the transfer area. (b) Except...

  5. Application of Effective Discharge Analysis to Environmental Flow Decision-Making

    NASA Astrophysics Data System (ADS)

    McKay, S. Kyle; Freeman, Mary C.; Covich, Alan P.

    2016-06-01

    Well-informed river management decisions rely on an explicit statement of objectives, repeatable analyses, and a transparent system for assessing trade-offs. These components may then be applied to compare alternative operational regimes for water resource infrastructure (e.g., diversions, locks, and dams). Intra- and inter-annual hydrologic variability further complicates these already complex environmental flow decisions. Effective discharge analysis (developed in studies of geomorphology) is a powerful tool for integrating temporal variability of flow magnitude and associated ecological consequences. Here, we adapt the effectiveness framework to include multiple elements of the natural flow regime (i.e., timing, duration, and rate-of-change) as well as two flow variables. We demonstrate this analytical approach using a case study of environmental flow management based on long-term (60 years) daily discharge records in the Middle Oconee River near Athens, GA, USA. Specifically, we apply an existing model for estimating young-of-year fish recruitment based on flow-dependent metrics to an effective discharge analysis that incorporates hydrologic variability and multiple focal taxa. We then compare three alternative methods of environmental flow provision. Percentage-based withdrawal schemes outcompete other environmental flow methods across all levels of water withdrawal and ecological outcomes.

  6. Application of Effective Discharge Analysis to Environmental Flow Decision-Making.

    PubMed

    McKay, S Kyle; Freeman, Mary C; Covich, Alan P

    2016-06-01

    Well-informed river management decisions rely on an explicit statement of objectives, repeatable analyses, and a transparent system for assessing trade-offs. These components may then be applied to compare alternative operational regimes for water resource infrastructure (e.g., diversions, locks, and dams). Intra- and inter-annual hydrologic variability further complicates these already complex environmental flow decisions. Effective discharge analysis (developed in studies of geomorphology) is a powerful tool for integrating temporal variability of flow magnitude and associated ecological consequences. Here, we adapt the effectiveness framework to include multiple elements of the natural flow regime (i.e., timing, duration, and rate-of-change) as well as two flow variables. We demonstrate this analytical approach using a case study of environmental flow management based on long-term (60 years) daily discharge records in the Middle Oconee River near Athens, GA, USA. Specifically, we apply an existing model for estimating young-of-year fish recruitment based on flow-dependent metrics to an effective discharge analysis that incorporates hydrologic variability and multiple focal taxa. We then compare three alternative methods of environmental flow provision. Percentage-based withdrawal schemes outcompete other environmental flow methods across all levels of water withdrawal and ecological outcomes. PMID:26961419

  7. Application of effective discharge analysis to environmental flow decision-making

    USGS Publications Warehouse

    McKay, S. Kyle; Freeman, Mary C.; Covich, A.P.

    2016-01-01

    Well-informed river management decisions rely on an explicit statement of objectives, repeatable analyses, and a transparent system for assessing trade-offs. These components may then be applied to compare alternative operational regimes for water resource infrastructure (e.g., diversions, locks, and dams). Intra- and inter-annual hydrologic variability further complicates these already complex environmental flow decisions. Effective discharge analysis (developed in studies of geomorphology) is a powerful tool for integrating temporal variability of flow magnitude and associated ecological consequences. Here, we adapt the effectiveness framework to include multiple elements of the natural flow regime (i.e., timing, duration, and rate-of-change) as well as two flow variables. We demonstrate this analytical approach using a case study of environmental flow management based on long-term (60 years) daily discharge records in the Middle Oconee River near Athens, GA, USA. Specifically, we apply an existing model for estimating young-of-year fish recruitment based on flow-dependent metrics to an effective discharge analysis that incorporates hydrologic variability and multiple focal taxa. We then compare three alternative methods of environmental flow provision. Percentage-based withdrawal schemes outcompete other environmental flow methods across all levels of water withdrawal and ecological outcomes.

  8. Aortic aneurysm repair - endovascular- discharge

    MedlinePlus

    ... page: //medlineplus.gov/ency/patientinstructions/000236.htm Aortic aneurysm repair - endovascular - discharge To use the sharing features ... enable JavaScript. AAA repair - endovascular - discharge; Repair - aortic aneurysm - endovascular - discharge; EVAR - discharge; Endovascular aneurysm repair - discharge ...

  9. Classification of river regimes: A context for hydroecology

    USGS Publications Warehouse

    Osterkamp, W.R.; Friedman, J.M.

    2000-01-01

    Over the past 30 years, ecologists have demostrated the importance of flow and temperature as primary variables in driving running water, riparian and floodplain ecosystems. As it is important to assess the size and timing of discharge variations in relation to those in temperature, a method is proposed that uses multivariate techniques to separately classify annual discharge and temperature regimes according to their 'shape' and 'magnitude', and which then combines the classifications. This paper: (i) describes a generally applicable method; (ii) tests the method by applying it to riparian systems on four British rivers using a 20-year record (1977-97) of flow and air temperature: (iii) proposes a hydroecological interpretation of the classification; (iv) considers the degree to which the methodology might provide information to support the design of ecologically acceptable flow regimes. 'Regimes' are defined for discharge and air temperature using monthly mean data. The results of applying the classification procedure to four British rivers indicates that the 'typical' regimes for each of the four catchments are composite features produced by a small number of clearly defined annual types that reflect interannual variability in hydroclimatological conditions. Annual discharge patterns are dominated by three 'shape' classes (accounting for 94% of the station years: class A, early (November) peak; class B, intermediate (December-January) peak; and class C, late (March) peak) and one 'magnitude' class (70% of the station years fall into class 3, intermediate), with two subordinate 'magnitude' classes: low-flow years (18%) and high flow years (12%). For air temperature, annual patterns are classified evenly into three 'shape' and four 'magnitude' classes. It is argued that this variety of flow-temperature patterns is important for sustaining ecosystem integrity and for establishing benchmark flow regimes and associated frequencies to aid river management. Copyright

  10. High-power spontaneous UV radiation source and its excitation regimes

    SciTech Connect

    Baksht, E Kh; Lomaev, Mikhail I; Panchenko, Aleksei N; Rybka, D V; Tarasenko, Viktor F; Krishnan, M; Thompson, J

    2005-07-31

    Different excitation regimes of a discharge in a xenon flashlamp are studied. It is shown that in passing from the oscillating discharge current to the unidirectional current pulse, the UV power radiation increases, while the FWHM of the radiation pulses decreases. The maximum UV power density of the discharge restricted by the flashlamp tube walls was {approx}700 and {approx}380 kW cm{sup -2} on the internal and external surfaces of the flashlamp tube, respectively. (active media)

  11. Device for generation of pulsed corona discharge

    DOEpatents

    Gutsol, Alexander F.; Fridman, Alexander; Blank, Kenneth; Korobtsev, Sergey; Shiryaevsky, Valery; Medvedev, Dmitry

    2012-05-08

    The invention is a method and system for the generation of high voltage, pulsed, periodic corona discharges capable of being used in the presence of conductive liquid droplets. The method and system can be used, for example, in different devices for cleaning of gaseous or liquid media using pulsed corona discharge. Specially designed electrodes and an inductor increase the efficiency of the system, permit the plasma chemical oxidation of detrimental impurities, and increase the range of stable discharge operations in the presence of droplets of water or other conductive liquids in the discharge chamber.

  12. Assessment, validation and intercomparison of operational models for predicting tritium migration from routine discharges of nuclear power plants: the case of Loire River.

    PubMed

    Goutal, Nicole; Luck, Marilyne; Boyer, Patrick; Monte, Luigi; Siclet, Françoise; Angeli, Giacomo

    2008-02-01

    During last decades, a number of projects have been launched to validate models for predicting the behaviour of radioactive substances in the environment. The project of the "Aquatic" working group of the project EMRAS (Environmental Modelling for Radiation Safety) organised by the International Atomic Energy Agency (IAEA) was based on the validation and assessment of models for predicting the behaviour of radionuclides in the aquatic ecosystems. The present paper describes a blind test of models aimed at assessing the dispersion of tritium releases in the Loire River (France), on a large domain ( approximately 350km) and on a period of six months, by comparing the results obtained by operational-to-experimental values of tritium concentration at Angers, a city along the Loire River. The common conclusion is that the models used by the different participants namely 1D models and models based on a schematic hydraulic (box models) are reliable tools for tritium transport modelling. Nevertheless, the importance of proper and detailed hydrological data for the appropriate prediction of pollutant migration in water is demonstrated by the example provided during this study. PMID:18068278

  13. Discharge coefficient correlations for circular-arc venturi flowmeters at critical /sonic/ flow

    NASA Technical Reports Server (NTRS)

    Arnberg, B. T.; Britton, C. L.; Seidl, W. F.

    1973-01-01

    Experimental data are analyzed to support theoretical predictions for discharge coefficients in circular-arc venturi flow meters operating in the critical sonic flow regime at throat Reynolds numbers above 150 thousand. The data tend to verify the predicted 0.25% decrease in the discharge coefficient during transition from a laminar to turbulent boundary layer. Four different test gases and three flow measurement facilities were used in the experiments with 17 venturis with throat sizes from 0.15 to 1.37 in. and Beta ratios ranging from 0.014 to 0.25. Recommendations are given as to how the effectiveness of future studies in the field could be improved.

  14. Pattern formation and dynamics of plasma filaments in dielectric barrier discharges

    NASA Astrophysics Data System (ADS)

    Callegari, T.; Bernecker, B.; Boeuf, J. P.

    2014-10-01

    Dielectric barrier discharges (DBDs) operating in a transient glow discharge regime offer a large variety of self-organized filamentary static or dynamical structures and constitute an excellent physical system for the study of nonlinear dynamics and pattern formation. The plasma filaments of DBDs can exhibit particle-like behavior, with motion, generation, annihilation, and scattering as well as collective effects leading to self-organized structures (hexagons, stripes, concentric rings, spirals, etc) that are typical of reaction-diffusion systems. The purpose of this paper is to analyze the detailed physics of pattern formation in DBDs on the basis of numerical fluid simulations and experiments in order to provide a deeper understanding of the nonlinear mechanisms responsible for the self-organization and dynamics of filaments.

  15. Electric winds driven by time oscillating corona discharges

    NASA Astrophysics Data System (ADS)

    Drews, Aaron M.; Cademartiri, Ludovico; Whitesides, George M.; Bishop, Kyle J. M.

    2013-10-01

    We investigate the formation of steady gas flows—so-called electric winds—created by point-plane corona discharges driven by time oscillating (ac) electric fields. By varying the magnitude and frequency of the applied field, we identify two distinct scaling regimes: (i) a low frequency (dc) regime and (ii) a high frequency (ac) regime. These experimental observations are reproduced and explained by a theoretical model describing the transport and recombination of ions surrounding the discharge and their contribution to the measured wind velocity. The two regimes differ in the spatial distribution of ions and in the process by which ions are consumed. Interestingly, we find that ac corona discharges generate strong electric forces localized near the tip of the point electrode, while dc corona discharges generate weaker forces distributed throughout the interelectrode region. Consequently, the velocity of the electric winds (>1 m/s) generated by ac discharges is largely independent of the position of the counter electrode. The unified theoretical description of dc and ac electric winds presented here reconciles previous observations of winds driven by dc corona and ac dielectric barrier discharges; insights from the model should also prove useful in the design of other plasma actuators.

  16. Characterization of the flowing afterglows of an N2 O2 reduced-pressure discharge: setting the operating conditions to achieve a dominant late afterglow and correlating the NOβ UV intensity variation with the N and O atom densities

    NASA Astrophysics Data System (ADS)

    Boudam, M. K.; Saoudi, B.; Moisan, M.; Ricard, A.

    2007-03-01

    The flowing afterglow of an N2-O2 discharge in the 0.6-10 Torr range is examined in the perspective of achieving sterilization of medical devices (MDs) under conditions ensuring maximum UV intensity with minimum damage to polymer-based MDs. The early afterglow is shown to be responsible for creating strong erosion damage, requiring that the sterilizer be operated in a dominant late-afterglow mode. These two types of afterglow can be characterized by optical emission spectroscopy: the early afterglow is distinguished by an intense emission from the N_{2}^{+} 1st negative system (band head at 391.4 nm) while the late afterglow yields an overpopulation of the v' = 11 ro-vibrational level of the N2(B) state, indicating a reduced contribution from the early afterglow N2 metastable species. We have studied the influence of operating conditions (pressure, O2 content in the N2-O2 mixture, distance of the discharge from the entrance to the afterglow (sterilizer) chamber) in order to achieve a dominant late afterglow that also ensures maximum and almost uniform UV intensity in the sterilization chamber. As far as operating conditions are concerned, moving the plasma source sufficiently far from the chamber entrance is shown to be a practical means for significantly reducing the density of the characteristic species of the early afterglow. Using the NO titration method, we obtain the (absolute) densities of N and O atoms in the afterglow at the NO injection inlet, a few cm before the chamber entrance: the N atom density goes through a maximum at approximately 0.3-0.5% O2 and then decreases, while the O atom density increases regularly with the O2 percentage. The spatial variation of the N atom (relative) density in the chamber is obtained by recording the emission intensity from the 1st positive system at 580 nm: in the 2-5 Torr range, this density is quite uniform everywhere in the chamber. The (relative) densities of N and O atoms in the discharge are determined by using

  17. Corona Discharge in Clouds

    NASA Astrophysics Data System (ADS)

    Sin'kevich, A. A.; Dovgalyuk, Yu. A.

    2014-04-01

    We present a review of the results of theoretical studies and laboratory modeling of corona discharge initiation in clouds. The influence of corona discharges on the evolution of the cloud microstructure and electrification is analyzed. It is shown that corona discharges are initiated when large-size hydrometeors approach each other, whereas in some cases, corona discharges from crystals, ice pellets, and hailstones can appear. The corona discharges lead to significant air ionization, charging of cloud particles, and separation of charges in clouds and initiate streamers and lightnings. The influence of corona discharges on changes in the phase composition of clouds is analyzed.

  18. Setup Aid for Electrical-Discharge Machining

    NASA Technical Reports Server (NTRS)

    Lines, G.; Duca, J.

    1985-01-01

    Interlock assures that workpiece is correctly assembled in machining fixture. A Plunger in a Hollow Shaft actuates a switch, allowing a power supply to produce current for electrical-discharge machining. Plunger operates only when necessary parts are position.

  19. Atmospheric sampling glow discharge ionization source

    DOEpatents

    McLuckey, Scott A.; Glish, Gary L.

    1989-01-01

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

  20. Atmospheric sampling glow discharge ionization source

    DOEpatents

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

    1989-07-18

    An atmospheric sampling glow discharge ionization source that can be used in combination with an analytical instrument which operates at high vacuum, such as a mass spectrometer. The atmospheric sampling glow discharge ionization source comprises a chamber with at least one pair of electrodes disposed therein, an inlet for a gaseous sample to be analyzed and an outlet communicating with an analyzer which operates at subatmospheric pressure. The ionization chamber is maintained at a pressure below atmospheric pressure, and a voltage difference is applied across the electrodes to induce a glow discharge between the electrodes, so that molecules passing through the inlet are ionized by the glow discharge and directed into the analyzer. The ionization source accepts the sample under atmospheric pressure conditions and processes it directly into the high vacuum instrument, bridging the pressure gap and drawing off unwanted atmospheric gases. The invention also includes a method for analyzing a gaseous sample using the glow discharge ionization source described above. 3 figs.

  1. State Waste Discharge Permit application, 183-N Backwash Discharge Pond

    SciTech Connect

    Not Available

    1994-06-01

    As part of the Hanford Federal Facility Agreement and Consent Order negotiations (Ecology et al. 1994), the US Department of Energy, Richland Operations Office, the US Environmental Protection Agency, and the Washington State Department of Ecology agreed that liquid effluent discharges to the ground on the Hanford Site which affect groundwater or have the potential to affect groundwater would be subject to permitting under the structure of Chapter 173--216 (or 173--218 where applicable) of the Washington Administrative Code, the State Waste Discharge Permit Program. As a result of this decision, the Washington State Department of Ecology and the US Department of Energy, Richland Operations Office entered into Consent Order No. DE91NM-177, (Ecology and DOE-RL 1991). The Consent Order No. DE91NM-177 requires a series of permitting activities for liquid effluent discharges. Liquid effluents on the Hanford Site have been classified as Phase I, Phase II, and Miscellaneous Streams. The Consent Order No. DE91NM-177 establishes milestones for State Waste Discharge Permit application submittals for all Phase I and Phase II streams, as well as the following 11 Miscellaneous Streams as identified in Table 4 of the Consent Order No. DE91NM-177.

  2. Appearance of a conductive carbonaceous coating in a CO2 dielectric barrier discharge and its influence on the electrical properties and the conversion efficiency

    NASA Astrophysics Data System (ADS)

    Belov, Igor; Paulussen, Sabine; Bogaerts, Annemie

    2016-02-01

    This work examines the properties of a dielectric barrier discharge (DBD) reactor, built for CO2 decomposition, by means of electrical characterization, optical emission spectroscopy and gas chromatography. The discharge, formed in an electronegative gas (such as CO2, but also O2), exhibits clearly different electrical characteristics, depending on the surface conductivity of the reactor walls. An asymmetric current waveform is observed in the metal-dielectric (MD) configuration, with sparse high-current pulses in the positive half-cycle (HC) and a more uniform regime in the negative HC. This indicates that the discharge is operating in two alternating regimes with rather different properties. At high CO2 conversion regimes, a conductive coating is deposited on the dielectric. This so-called coated MD configuration yields a symmetric current waveform, with current peaks in both the positive and negative HCs. In a double-dielectric (DD) configuration, the current waveform is also symmetric, but without current peaks in both the positive and negative HC. Finally, the DD configuration with conductive coating on the inner surface of the outer dielectric, i.e. so-called coated DD, yields again an asymmetric current waveform, with current peaks in the negative HC. These different electrical characteristics are related to the presence of the conductive coating on the dielectric wall of the reactor and can be explained by an increase of the local barrier capacitance available for charge transfer. The different discharge regimes affect the CO2 conversion, more specifically, the CO2 conversion is lowest in the clean DD configuration. It is somewhat higher in the coated DD configuration, and still higher in the MD configuration. The clean and coated MD configuration, however, gave similar CO2 conversion. These results indicate that the conductivity of the dielectric reactor walls can highly promote the development of the high-amplitude discharge current pulses and

  3. Pediatric heart surgery - discharge

    MedlinePlus

    ... reduced appetite Alternate Names Congenital heart surgery - discharge; Patent ductus arteriosus ligation - discharge; Hypoplastic left heart repair - ... of the aorta Congenital heart defect - corrective surgery Patent ductus arteriosus Pediatric heart surgery Tetralogy of Fallot ...

  4. Elbow replacement - discharge

    MedlinePlus

    Total elbow arthroplasty - discharge; Endoprosthetic elbow replacement - discharge ... You had surgery to replace your elbow joint with artificial joint parts (prosthetics). The surgeon made a cut (incision) in the back of your upper or lower arm and ...

  5. Hysterectomy - abdominal - discharge

    MedlinePlus

    ... fibroids Patient Instructions Getting out of bed after surgery Hysterectomy - laparoscopic - discharge Hysterectomy - vaginal - discharge Update Date 1/16/2015 Updated by: Cynthia D. White, MD, Fellow American College of Obstetricians and Gynecologists, Group Health Cooperative, Bellevue, WA. ...

  6. Foot amputation - discharge

    MedlinePlus

    Amputation - foot - discharge; Trans-metatarsal amputation - discharge ... You have had a foot amputation. You may have had an accident, or your foot may have had an infection or disease and doctors could ...

  7. Nurse-led discharge.

    PubMed

    Page, Carole

    2010-12-01

    Delayed discharges have financial implications for hospital trusts and cause dissatisfaction for patients and their families. This article looks at nurse-led discharge pathways at Milton Keynes Hospital's ambulatory care unit. It explains how giving nurses the responsibility to discharge has improved the patient experience, made nurses more accountable and saved money for the trust. PMID:21229868

  8. Anti-reflux surgery - children - discharge

    MedlinePlus

    Fundoplication - children - discharge; Nissen fundoplication - children - discharge; Belsey (Mark IV) fundoplication - children - discharge; Toupet fundoplication - children - discharge; Thal fundoplication - ...

  9. 46 CFR 154.1838 - Discharge by gas pressurization.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Discharge by gas pressurization. 154.1838 Section 154... SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Operations § 154.1838 Discharge by gas pressurization. The person in charge of cargo transfer may not authorize cargo discharge...

  10. 46 CFR 154.1838 - Discharge by gas pressurization.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Discharge by gas pressurization. 154.1838 Section 154... SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Operations § 154.1838 Discharge by gas pressurization. The person in charge of cargo transfer may not authorize cargo discharge...

  11. 46 CFR 154.1838 - Discharge by gas pressurization.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Discharge by gas pressurization. 154.1838 Section 154... SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Operations § 154.1838 Discharge by gas pressurization. The person in charge of cargo transfer may not authorize cargo discharge...

  12. 33 CFR 154.545 - Discharge containment equipment.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Discharge containment equipment....545 Discharge containment equipment. (a) Each facility must have ready access to enough containment material and equipment to contain any oil or hazardous material discharged on the water from operations...

  13. 33 CFR 154.545 - Discharge containment equipment.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Discharge containment equipment....545 Discharge containment equipment. (a) Each facility must have ready access to enough containment material and equipment to contain any oil or hazardous material discharged on the water from operations...

  14. Environment Flow Assessment with Flow Regime Transition

    NASA Astrophysics Data System (ADS)

    Su, J.; Ho, C. C.; Chang, L. C.

    2015-12-01

    To avoid worsen river and estuarine ecosystems cause by overusing water resources, environmental flows conservation is applied to reduce the impact of river environment. Environmental flows refer to water provided within a river, wetland or coastal zone to sustain ecosystems and benefits to human wellbeing. Environment flow assessment is now widely accepted that a naturally variable flow regime, rather than just a minimum low flow. In this study, we propose four methods, experience method, Tenant method, hydraulic method and habitat method to assess the environmental flow of base flow, flush flow and overbank flow with different discharge, frequency and occurrence period. Dahan River has been chosen as a case to demonstrate the assessment mechanism. The alternatives impact analysis of environment and human water used provides a reference for stakeholders when holding an environmental flow consultative meeting.

  15. Carburetor fuel discharge assembly

    SciTech Connect

    Yost, R.M.

    1993-06-29

    An improved carburetor for use on an internal combustion engine is described, the carburetor having an airflow passage and fuel discharge means for admitting fuel into the airflow passage for mixing the fuel with air flowing in the airflow passage to form a fuel/air mixture to be supplied to the combustion chamber(s) of the engine, the fuel discharge means including a fuel discharge assembly which comprises a hollow discharge tube and fuel supplying means connected to the discharge tube for admitting fuel into the interior of the discharge tube, wherein the discharge tube has a longitudinal internal bore in fluid communication with the fuel supplying means, wherein the internal bore extends between an inlet that is closest to the fuel supplying means and an outlet that is furthest from the fuel supplying means with the outlet of the bore being located within the airflow passage of the carburetor to supply fuel into this passage after the fuel passes from the fuel supplying means through the internal bore of the discharge tube, wherein the improvement relates to the fuel discharge assembly and comprises: a hollow fuel flow guide tube telescopically received inside the internal bore of the discharge tube, wherein the fuel flow guide tube extends from approximately the location of the inlet of the bore up at least a portion of the length of the bore towards the outlet of the bore to conduct fuel from the fuel supplying means into the bore of the discharge tube.

  16. Nonsputtering impulse magnetron discharge

    SciTech Connect

    Khodachenko, G. V.; Mozgrin, D. V.; Fetisov, I. K.; Stepanova, T. V.

    2012-01-15

    Experiments with quasi-steady high-current discharges in crossed E Multiplication-Sign B fields in various gases (Ar, N{sub 2}, H{sub 2}, and SF{sub 6}) and gas mixtures (Ar/SF{sub 6} and Ar/O{sub 2}) at pressures from 10{sup -3} to 5 Torr in discharge systems with different configurations of electric and magnetic fields revealed a specific type of stable low-voltage discharge that does not transform into an arc. This type of discharge came to be known as a high-current diffuse discharge and, later, a nonsputtering impulse magnetron discharge. This paper presents results from experimental studies of the plasma parameters (the electron temperature, the plasma density, and the temperature of ions and atoms of the plasma-forming gas) of a high-current low-pressure diffuse discharge in crossed E Multiplication-Sign B fields.

  17. 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.

  18. Examination Regimes and Student Achievement

    ERIC Educational Resources Information Center

    Cosentino de Cohen, Clemencia

    2010-01-01

    Examination regimes at the end of secondary school vary greatly intra- and cross-nationally, and in recent years have undergone important reforms often geared towards increasing student achievement. This research presents a comparative analysis of the relationship between examination regimes and student achievement in the OECD. Using a micro…

  19. Sensitivity of streamflows to hydroclimatic fluctuations: resilience and regime shifts

    NASA Astrophysics Data System (ADS)

    Botter, Gianluca; Basso, Stefano; Rodriguez-Iturbe, Ignacio; Rinaldo, Andrea

    2016-04-01

    Landscape and climate alterations foreshadow global-scale shifts of river flow regimes. However, a theory that identifies the range of foreseen impacts on streamflows resulting from inhomogeneous forcings and sensitivity gradients across diverse regimes is lacking. In this contribution, we use a dimensionless index embedding simple climate and landscape attributes (the ratio of the mean interarrival of streamflow-producing rainfall events and the mean catchment response time) to discriminate erratic regimes with enhanced intra-seasonal streamflow variability from persistent regimes endowed with regular flow patterns. The proposed classification is successfully applied to 110 seasonal streamflow distributions observed in 44 catchments of the Alps and the United States, allowing the identification of emerging patterns in space and time. In the same framework, the impact of multi-scale fluctuations of the underlying climatic drivers (temperature, precipitation) on the streamflow distributions can be analyzed. Theoretical and empirical data show that erratic regimes, typical of rivers with low mean discharges, are highly resilient in that they hold a reduced sensitivity to variations in the external forcing. Specific temporal trajectories of streamflow distributions and flow regime shifts driven by land-cover change and rainfall patterns can be also evidenced. The approach developed offers an objective basis for the analysis and prediction of the impact of climate/landscape change on water resources.

  20. Angioplasty and stent - heart - discharge

    MedlinePlus

    ... discharge; PTCA - discharge; Percutaneous transluminal coronary angioplasty - discharge; Heart artery dilatation - discharge ... the blood vessels that supply blood to your heart. You may have had a heart attack or ...

  1. Quasi-perpetual discharge behaviour in p-type Ge-air batteries.

    PubMed

    Ocon, Joey D; Kim, Jin Won; Abrenica, Graniel Harne A; Lee, Jae Kwang; Lee, Jaeyoung

    2014-11-01

    Metal-air batteries continue to become attractive energy storage and conversion systems due to their high energy and power densities, safer chemistries, and economic viability. Semiconductor-air batteries - a term we first define here as metal-air batteries that use semiconductor anodes such as silicon (Si) and germanium (Ge) - have been introduced in recent years as new high-energy battery chemistries. In this paper, we describe the excellent doping-dependent discharge kinetics of p-type Ge anodes in a semiconductor-air cell employing a gelled KOH electrolyte. Owing to its Fermi level, n-type Ge is expected to have lower redox potential and better electronic conductivity, which could potentially lead to a higher operating voltage and better discharge kinetics. Nonetheless, discharge measurements demonstrated that this prediction is only valid at the low current regime and breaks down at the high current density region. The p-type Ge behaves extremely better at elevated currents, evident from the higher voltage, more power available, and larger practical energy density from a very long discharge time, possibly arising from the high overpotential for surface passivation. A primary semiconductor-air battery, powered by a flat p-type Ge as a multi-electron anode, exhibited an unprecedented full discharge capacity of 1302.5 mA h gGe(-1) (88% anode utilization efficiency), the highest among semiconductor-air cells, notably better than new metal-air cells with three-dimensional and nanostructured anodes, and at least two folds higher than commercial Zn-air and Al-air cells. We therefore suggest that this study be extended to doped-Si anodes, in order to pave the way for a deeper understanding on the discharge phenomena in alkaline metal-air conversion cells with semiconductor anodes for specific niche applications in the future. PMID:24975009

  2. ESTIMATION OF NAVIGATION - DAM DISCHARGE IN ILLINOIS.

    USGS Publications Warehouse

    Weiss, Linda S.

    1987-01-01

    Techniques were used to estimate discharge for the Brandon Road Dam on the Des Plaines River and the Dresden Island, Marseilles, and Starved Rock Dams on the Illinois River in northern Illinois. Tainter gates are operated to regulate streamflow at all dams. Additionally, headgates are used for regulation of the Brandon Road Dam. Stage-discharge, gate-opening relations were developed from a total of 91 discharge measurements that range from 198 to 86,400 cubic feet per second (5. 6 to 2,450 cubic meters per second). Values for discharge coefficients, in equations that express discharge as a function of tailwater depth, headwater depth, and vertical height of gate opening, were determined for conditions of free-orifice, submerged-orifice, free-weir, and submerged-weir flow past a tainter gate.

  3. Supersonic CO electric-discharge lasers

    NASA Technical Reports Server (NTRS)

    Hason, R. K.; Mitchner, M.; Stanton, A.

    1975-01-01

    Laser modeling activity is described which involved addition of an option allowing N2 as a second diatomic gas. This option is now operational and a few test cases involving N2/CO mixtures were run. Results from these initial test cases are summarized. In the laboratory, a CW double-discharge test facility was constructed and tested. Features include: water-cooled removable electrodes, O-ring construction to facilitate cleaning and design modifications, increased discharge length, and addition of a post-discharge observation section. Preliminary tests with this facility using N2 yielded higher power loadings than obtained in the first-generation facility. Another test-section modification, recently made and as yet untested, will permit injection of secondary gases into the cathode boundary layer. The objective will be to vary and enhance the UV emission spectrum from the auxiliary discharge, thereby influencing the level of photoionization in the main discharge region.

  4. Discharging dynamics in an electrolytic cell

    NASA Astrophysics Data System (ADS)

    Feicht, Sarah E.; Frankel, Alexandra E.; Khair, Aditya S.

    2016-07-01

    We analyze the dynamics of a discharging electrolytic cell comprised of a binary symmetric electrolyte between two planar, parallel blocking electrodes. When a voltage is initially applied, ions in the electrolyte migrate towards the electrodes, forming electrical double layers. After the system reaches steady state and the external current decays to zero, the applied voltage is switched off and the cell discharges, with the ions eventually returning to a uniform spatial concentration. At voltages on the order of the thermal voltage VT=kBT /q ≃25 mV, where kB is Boltzmann's constant, T is temperature, and q is the charge of a proton, experiments on surfactant-doped nonpolar fluids observe that the temporal evolution of the external current during charging and discharging is not symmetric [V. Novotny and M. A. Hopper, J. Electrochem. Soc. 126, 925 (1979), 10.1149/1.2129195; P. Kornilovitch and Y. Jeon, J. Appl. Phys. 109, 064509 (2011), 10.1063/1.3554445]. In fact, at sufficiently large voltages (several VT), the current during discharging is no longer monotonic: it displays a "reverse peak" before decaying in magnitude to zero. We analyze the dynamics of discharging by solving the Poisson-Nernst-Planck equations governing ion transport via asymptotic and numerical techniques in three regimes. First, in the "linear regime" when the applied voltage V is formally much less than VT, the charging and discharging currents are antisymmetric in time; however, the potential and charge density profiles during charging and discharging are asymmetric. The current evolution is on the R C timescale of the cell, λDL /D , where L is the width of the cell, D is the diffusivity of ions, and λD is the Debye length. Second, in the (experimentally relevant) thin-double-layer limit ɛ =λD/L ≪1 , there is a "weakly nonlinear" regime defined by VT≲V ≲VTln(1 /ɛ ) , where the bulk salt concentration is uniform; thus the R C timescale of the evolution of the current magnitude

  5. Discharging dynamics in an electrolytic cell.

    PubMed

    Feicht, Sarah E; Frankel, Alexandra E; Khair, Aditya S

    2016-07-01

    We analyze the dynamics of a discharging electrolytic cell comprised of a binary symmetric electrolyte between two planar, parallel blocking electrodes. When a voltage is initially applied, ions in the electrolyte migrate towards the electrodes, forming electrical double layers. After the system reaches steady state and the external current decays to zero, the applied voltage is switched off and the cell discharges, with the ions eventually returning to a uniform spatial concentration. At voltages on the order of the thermal voltage V_{T}=k_{B}T/q≃25 mV, where k_{B} is Boltzmann's constant, T is temperature, and q is the charge of a proton, experiments on surfactant-doped nonpolar fluids observe that the temporal evolution of the external current during charging and discharging is not symmetric [V. Novotny and M. A. Hopper, J. Electrochem. Soc. 126, 925 (1979)JESOAN0013-465110.1149/1.2129195; P. Kornilovitch and Y. Jeon, J. Appl. Phys. 109, 064509 (2011)JAPIAU0021-897910.1063/1.3554445]. In fact, at sufficiently large voltages (several V_{T}), the current during discharging is no longer monotonic: it displays a "reverse peak" before decaying in magnitude to zero. We analyze the dynamics of discharging by solving the Poisson-Nernst-Planck equations governing ion transport via asymptotic and numerical techniques in three regimes. First, in the "linear regime" when the applied voltage V is formally much less than V_{T}, the charging and discharging currents are antisymmetric in time; however, the potential and charge density profiles during charging and discharging are asymmetric. The current evolution is on the RC timescale of the cell, λ_{D}L/D, where L is the width of the cell, D is the diffusivity of ions, and λ_{D} is the Debye length. Second, in the (experimentally relevant) thin-double-layer limit ε=λ_{D}/L≪1, there is a "weakly nonlinear" regime defined by V_{T}≲V≲V_{T}ln(1/ε), where the bulk salt concentration is uniform; thus the RC timescale of

  6. Photon blockade in the ultrastrong coupling regime.

    PubMed

    Ridolfo, A; Leib, M; Savasta, S; Hartmann, M J

    2012-11-01

    We explore photon coincidence counting statistics in the ultrastrong coupling regime, where the atom-cavity coupling rate becomes comparable to the cavity resonance frequency. In this regime, usual normal order correlation functions fail to describe the output photon statistics. By expressing the electric-field operator in the cavity-emitter dressed basis, we are able to propose correlation functions that are valid for arbitrary degrees of light-matter interaction. Our results show that the standard photon blockade scenario is significantly modified for ultrastrong coupling. We observe parametric processes even for two-level emitters and temporal oscillations of intensity correlation functions at a frequency given by the ultrastrong photon emitter coupling. These effects can be traced back to the presence of two-photon cascade decays induced by counterrotating interaction terms. PMID:23215383

  7. Steady and transient regimes in hydropower plants

    NASA Astrophysics Data System (ADS)

    Gajic, A.

    2013-12-01

    Hydropower plant that has been in operation for about 30 years has to be reconstructed. They have already installed 12 Kaplan turbines, the largest in the world at that time. The existing CAM relationship was determined based on hydraulic model tests and checked by efficiency on-site tests. It was also tested based on turbine bearing vibrations. In order to discover vibrations and long cracks on stay vanes detailed on-site measurements were performed. Influence of the modification of the trailing edges on the dynamic stresses of the stay vanes is also shown. In order to improve power output transient regimes were analyzed, both experimentally and numerically. Reversible hydropower plant, a pioneer in Europe since it was the first Pump storage power plant constructed with the highest head pump-turbines in the world. Analyses of transient regimes discover some problems with S-shaped characteristics coupled with non-symmetrical penstock.

  8. Computing discharge using the index velocity method

    USGS Publications Warehouse

    Levesque, Victor A.; Oberg, Kevin A.

    2012-01-01

    Application of the index velocity method for computing continuous records of discharge has become increasingly common, especially since the introduction of low-cost acoustic Doppler velocity meters (ADVMs) in 1997. Presently (2011), the index velocity method is being used to compute discharge records for approximately 470 gaging stations operated and maintained by the U.S. Geological Survey. The purpose of this report is to document and describe techniques for computing discharge records using the index velocity method. Computing discharge using the index velocity method differs from the traditional stage-discharge method by separating velocity and area into two ratings—the index velocity rating and the stage-area rating. The outputs from each of these ratings, mean channel velocity (V) and cross-sectional area (A), are then multiplied together to compute a discharge. For the index velocity method, V is a function of such parameters as streamwise velocity, stage, cross-stream velocity, and velocity head, and A is a function of stage and cross-section shape. The index velocity method can be used at locations where stage-discharge methods are used, but it is especially appropriate when more than one specific discharge can be measured for a specific stage. After the ADVM is selected, installed, and configured, the stage-area rating and the index velocity rating must be developed. A standard cross section is identified and surveyed in order to develop the stage-area rating. The standard cross section should be surveyed every year for the first 3 years of operation and thereafter at a lesser frequency, depending on the susceptibility of the cross section to change. Periodic measurements of discharge are used to calibrate and validate the index rating for the range of conditions experienced at the gaging station. Data from discharge measurements, ADVMs, and stage sensors are compiled for index-rating analysis. Index ratings are developed by means of regression

  9. Radionuclides, Metals, and Hydrocarbons in Oil and Gas Operational Discharges and Environmental Samples Associated with Offshore Production Facilities on the Texas/Louisiana Continental Shelf with an Environmental Assessment of Metals and Hydrocarbons

    SciTech Connect

    Continental Shelf Associates, Inc.

    1999-08-16

    This report presents concentrations of radionuclides, metals, and hydrocarbons in samples of produced water and produced sand from oil and gas production platforms located offshore Texas and Louisiana. Concentrations in produced water discharge plume/receiving water, ambient seawater, sediment, interstitial water, and marine animal tissue samples collected in the vicinity of discharging platforms and reference sites distant from discharges are also reported and discussed. An environmental risk assessment is made on the basis of the concentrations of metals and hydrocarbons determined in the samples.

  10. Radionuclides, Metals, and Hydrocarbons in Oil and Gas Operational Discharges and Environmental Samples Associated with Offshore Production Facilities on the Texas/Louisiana Continental Shelf with an Environmental Assessment of Metals and Hydrocarbons.

    SciTech Connect

    1997-06-01

    This report presents concentrations of radionuclides, metals, and hydrocarbons in samples of produced water and produced sand from oil and gas production platforms located offshore Texas and Louisiana. concentrations in produced water discharge plume / receiving water, ambient seawater, sediment, interstitial water, and marine animal tissue samples collected in the vicinity of discharging platforms and reference sites distant from discharges are also reported and discussed. An environmental risk assessment is made on the basis of the concentration of metals and hydrocarbons determined in the samples.

  11. Pelvic radiation - discharge

    MedlinePlus

    Radiation of the pelvis - discharge; Cancer treatment - pelvic radiation; Prostate cancer - pelvic radiation; Ovarian cancer - pelvic radiation; Cervical cancer - pelvic radiation; Uterine cancer - pelvic radiation; Rectal cancer - ...

  12. Stochastic regimes in very-low-frequency fluidic oscillator

    NASA Astrophysics Data System (ADS)

    Tesař, Václav

    2016-03-01

    Paper discusses interesting unexpected stochastic regimes discovered in a fluidic oscillator designed for operation at very low oscillation frequencies - without the inconvenience of the long feedback loops needed in standard low-frequency oscillator designs. The new oscillator contains a pair of bistable turn-down active valves operating in anti-parallel — essentially analogous to Abraham & Bloch electric "multibrateur" invented in 1919. Three different self-excited oscillation regimes were found. In the order of increasing supplied flow rate, these regimes are characterised by: (A) generation of stochastic-duration multi-pulse packs, (B) generation of individual pulses with a degree of periodicity, and (C) regime with randomly appearing flow pulses separated by intervals of the order of seconds.

  13. Dynamics and density distributions in a capillary-discharge waveguide with an embedded supersonic jet

    SciTech Connect

    Matlis, N. H. Gonsalves, A. J.; Steinke, S.; Tilborg, J. van; Shaw, B.; Mittelberger, D. E.; Geddes, C. G. R.; Matlis, E. H.; Leemans, W. P.

    2015-11-28

    We present an analysis of the gas dynamics and density distributions within a capillary-discharge waveguide with an embedded supersonic jet. This device provides a target for a laser plasma accelerator which uses longitudinal structuring of the gas-density profile to enable control of electron trapping and acceleration. The functionality of the device depends sensitively on the details of the density profile, which are determined by the interaction between the pulsed gas in the jet and the continuously-flowing gas in the capillary. These dynamics are captured by spatially resolving recombination light from several emission lines of the plasma as a function of the delay between the jet and the discharge. We provide a phenomenological description of the gas dynamics as well as a quantitative evaluation of the density evolution. In particular, we show that the pressure difference between the jet and the capillary defines three regimes of operation with qualitatively different longitudinal density profiles and show that jet timing provides a sensitive method for tuning between these regimes.

  14. Ion kinetics and self pulsing in DC microplasma discharges at atmospheric and higher pressure

    NASA Astrophysics Data System (ADS)

    Mahamud, Rajib; Farouk, Tanvir I.

    2016-04-01

    Atmospheric pressure microplasma devices have been the subject of considerable interest and research during the last decade. Most of the operation regime of the plasma discharges studied fall in the ‘abnormal’, ‘normal’ and ‘corona’ modes—increasing and a ‘flat’ voltage current characteristics. However, the negative differential resistance regime at atmospheric and high pressures has been less studied and possesses unique characteristics that can be employed for novel applications. In this work, the role of ion kinetics especially associated with trace impurities; on the self pulsing behavior has been investigated. Detailed numerical simulations have been conducted with a validated model for a helium-nitrogen feed gas mixture. Different oscillatory modes were observed where the discharge was found to undergo complete or partial relaxation. Trace amount of nitrogen was found to significantly alter the pulsing characteristics. External parameters influencing these self oscillations are also studied and aspects of the ion kinetics on the oscillatory behavior are discussed.

  15. Parameters of an electric-discharge generator of iodine atoms for a chemical oxygen-iodine laser

    SciTech Connect

    Azyazov, V N; Vorob'ev, M V; Voronov, A I; Kupryaev, Nikolai V; Mikheev, P A; Ufimtsev, N I

    2009-01-31

    Laser-induced fluorescence is used for measuring the concentration of iodine molecules at the output of an electric-discharge generator of atomic iodine. Methyl iodide CH{sub 3}I is used as the donor of atomic iodine. The fraction of iodine extracted from CH{sub 3}I in the generator is {approx}50%. The optimal operation regimes are found in which 80%-90% of iodine contained in the output flow of the generator was in the atomic state. This fraction decreased during the iodine transport due to recombination and was 20%-30% at the place where iodine was injected into the oxygen flow. The fraction of the discharge power spent for dissociation was {approx}3%. (elements of laser setups)

  16. Discharge transient coupling in large space power systems

    NASA Technical Reports Server (NTRS)

    Stevens, N. John; Stillwell, R. P.

    1990-01-01

    Experiments have shown that plasma environments can induce discharges in solar arrays. These plasmas simulate the environments found in low earth orbits where current plans call for operation of very large power systems. The discharges could be large enough to couple into the power system and possibly disrupt operations. Here, the general concepts of the discharge mechanism and the techniques of coupling are discussed. Data from both ground and flight experiments are reviewed to obtain an expected basis for the interactions. These concepts were applied to the Space Station solar array and distribution system as an example of the large space power system. The effect of discharges was found to be a function of the discharge site. For most sites in the array discharges would not seriously impact performance. One location at the negative end of the array was identified as a position where discharges could couple to charge stored in system capacitors. This latter case could impact performance.

  17. Longitudinal discharge laser electrodes

    DOEpatents

    Warner, B.E.; Miller, J.L.; Ault, E.R.

    1994-08-23

    The improved longitudinal discharge laser electrode with IR baffle includes an electrode made up of washers spaced along the laser axis in order to form inter-washer spaces for hollow cathode discharge to take place and for IR radiation to be trapped. Additional IR baffles can be placed between the electrode ann the window. 2 figs.

  18. Longitudinal discharge laser electrodes

    DOEpatents

    Warner, Bruce E.; Miller, John L.; Ault, Earl R.

    1994-01-01

    The improved longitudinal discharge laser electrode with IR baffle includes an electrode made up of washers spaced along the laser axis in order to form inter-washer spaces for hollow cathode discharge to take place and for IR radiation to be trapped. Additional IR baffles can be placed between the electrode ann the window.

  19. Lithium battery discharge tests

    NASA Technical Reports Server (NTRS)

    Johnson, C. J.

    1980-01-01

    The long term discharge of a variety of lithium cells was characterized and the susceptibility of the cells to chemical variation during the slow discharge was tested. A shunt resistor was set across the terminals to monitor the voltage as a function of time. Failures were identified by premature voltage drops.

  20. 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.

  1. CO-AXIAL DISCHARGES

    DOEpatents

    Luce, J.S.; Smith, L.P.

    1960-11-22

    A method and apparatus are given for producing coaxial arc discharges in an evacuated enclosure and within a strong, confining magnetic field. The arcs are maintained at a high potential difference. Electrons will diffuse to the more positive arc from the negative arc, and positive ions will diffuse from the more positive arc to the negative arc. Coaxial arc discharges have the advantage that ions which return to strike the positive arc discharge will lose no energy since they do not strike a solid wall or electrode. Those discharges are useful in confining an ionized plasma between the discharges, and have the advantage of preventing impurities from the walls of the enclosure from entering ihe plasma area because of the arc barrier set up bv the cylindrical outer arc.

  2. Co-axial discharges

    DOEpatents

    Luce, J. S.; Smith, L. P.

    1960-11-22

    An apparatus is described for producing coaxial arc discharges in an evacuated enclosure and within a strong, confining magnetic field. The arcs are maintained at a high potential difference. Electrons diffuse to the more positive arc from the negative arc, and positive ions diffuse from the more positive arc to the negative arc. Coaxial arc discharges have the advantuge that ions that return to strike the positive arc discharge will lose no energy since they do not strike a solid wall or electrode. These discharges are useful in confining an ionized plasma between the discharges and have the advantage of preventing impurities from the walls of the enclosure from entering the plasma area because of the arc barrier set up by the cylindrical outer arc. (auth)

  3. Silane discharge ion chemistry

    SciTech Connect

    Chatham, R.H. III

    1984-01-01

    Silane dc, rf, and dc proximity discharges have been studied using mass spectroscopic measurements of the positive ions as a detailed diagnostic for the type of discharge used to produce hydrogenated amorphous silicon solar photovoltaic cells. The properties and quality of these films depends in a very complex way upon the interactions of the many reactive neutral and ion species in the discharge. Qualitative models of the ion chemical processes in these discharges have been developed from experimental measurements. Knowledge of the ion-molecule and electron-molecule collision cross sections is important to any attempt at understanding silane discharge chemistry. Consequently, the electron impact ionization cross sections for silane and disilane have been measured and for comparison purposes also for methane and ethane. In addition, the rate coefficients for charge exchange reactions of He , Ne , and Ar with silane, disilane, methane, and ethane have been measured as these are important to understanding discharges in inert gas-silane mixtures. A detailed quantitative model of the cathode sheath region of a silane dc discharge has been developed by extending the best recent calculation of the electron motion in the sheath to a self-consistent form which includes the ion motion. This model is used with comparison of silane dc discharge data to diagnose the ion chemistry occurring in the sheath region of silane dc discharge. The understanding of the discharge ion chemical processes that have been gained in this study represent an important step toward understanding the chemical and physical processes leading to film growth.

  4. The Electrical Characteristics of a Filamentary Dielectric Barrier Discharge

    SciTech Connect

    Tay, W. H.; Yap, S. L.; Wong, C. S.

    2010-07-07

    The electrical characteristics of a filamentary dielectric barrier discharge using parallel-plate electrodes geometry were statistically studied. The DBD's system was powered by a 50 Hz power supply and operated at atmospheric pressure. The influence of the air gap and position of dielectric on the discharge had been investigated. It was found that the air gap distance and position of dielectric had significant influence on the discharge current pulse. The results showed that discharge with large distance between the high voltage electrode and the dielectric would generate higher current pulses during the positive cycle. The discharge energy of single pulse was also determined.

  5. Low-current hollow-cathode discharge in a trigger unit of a cold cathode thyratron

    NASA Astrophysics Data System (ADS)

    Landl, N. V.; Korolev, Y. D.; Frants, O. B.; Geyman, V. G.; Bolotov, A. V.

    2015-11-01

    The paper deals with the investigations of the effect of cathode emissivity on the regimes of low-current hollow-cathode glow discharge. It is shown that an increase in the emissivity due to the so-called high-emissivity tablet allows the essential decrease in the discharge initiation voltage and the discharge burning voltage. The model of current sustaining for the hollow-cathode discharge, which takes into account the external emission current has been developed. On basis of the model, the current-voltage characteristics of the discharge have been interpreted.

  6. Long term (1921-2011) hydrological regime of Alpine catchments in Northern Italy

    NASA Astrophysics Data System (ADS)

    Bocchiola, D.

    2014-08-01

    Long term (1921-2011) yearly and seasonal hydrological regime of 23 Alpine rivers in Northern Italy (ca. 102-104 km2) was investigated here. First, for regulated catchment, the potential effect of flow storage was investigated using an index of potential flow regulation, and pre and post reservoirs' installation flow analysis. For catchments displaying little regulation effect, non stationarity was studied using linear regression, including variable (segmented) slope analysis, and Mann Kendall test, traditional and progressive. The link of the observed trends against descriptive physiographic variables was then investigated, to highlight geographic and topographic patterns of changes of the hydrological cycle. Dependence upon global thermal and North Atlantic Oscillation NAO anomalies were analysed to highlight potential impact of large scale climate drivers against regional hydrological regimes. Also, the correlation between stream flows and climatic drivers of precipitation and temperatures in nearby stations was investigated, to highlight climate trends potentially driving hydrological changes, and potential changes in the nexus between climate and hydrology given by reservoirs' operation. The results display for several Alpine rivers here likelihood of significant changes of hydrological fluxes, notably during Winter, Spring and Summer. Winter discharges is decreasing on average, but decrease is seen below 1800 m a.s.l. or so, while increase is found above, and the more Northern the larger the increase. Discharges during Spring mostly decrease in time, and more so for increasing outlet altitude, while Summer specific discharges always decrease, and more notably with increasing altitude of the contributing catchment. NAO and global thermal anomalies are correlated against the rate of variation of hydrological fluxes, with the intensity of correlation linked to altitude, longitude, and basin's size. Specifically targeted studies are necessary to investigate the

  7. Electric field in an AC dielectric barrier discharge overlapped with a nanosecond pulse discharge

    NASA Astrophysics Data System (ADS)

    Goldberg, Benjamin M.; Shkurenkov, Ivan; Adamovich, Igor V.; Lempert, Walter R.

    2016-08-01

    The effect of ns discharge pulses on the AC barrier discharge in hydrogen in plane-to-plane geometry is studied using time-resolved measurements of the electric field in the plasma. The AC discharge was operated at a pressure of 300 Torr at frequencies of 500 and 1750 Hz, with ns pulses generated when the AC voltage was near zero. The electric field vector is measured by ps four-wave mixing technique, which generates coherent IR signal proportional to the square of electric field. Absolute calibration was done using an electrostatic (sub-breakdown) field applied to the discharge electrodes, when no plasma was generated. The results are compared with one-dimensional kinetic modeling of the AC discharge and the nanosecond pulse discharge, predicting behavior of both individual micro-discharges and their cumulative effect on the electric field distribution in the electrode gap, using stochastic averaging based on the experimental micro-discharge temporal probability distribution during the AC period. Time evolution of the electric field in the AC discharge without ns pulses, controlled by a superposition of random micro-discharges, exhibits a nearly ‘flat top’ distribution with the maximum near breakdown threshold, reproduced quite well by kinetic modeling. Adding ns pulse discharges on top of the AC voltage waveform changes the AC discharge behavior in a dramatic way, inducing transition from random micro-discharges to a more regular, near-1D discharge. In this case, reproducible volumetric AC breakdown is produced at a well-defined moment after each ns pulse discharge. During the reproducible AC breakdown, the electric field in the plasma exhibits a sudden drop, which coincides in time with a well-defined current pulse. This trend is also predicted by the kinetic model. Analysis of kinetic modeling predictions shows that this effect is caused by large-volume ionization and neutralization of surface charges on the dielectrics by ns discharge pulses. The present

  8. Discharge lamp technologies

    NASA Technical Reports Server (NTRS)

    Dakin, James

    1994-01-01

    This talk is an overview of discharge lamp technology commonly employed in general lighting, with emphasis on issues pertinent to lighting for plant growth. Since the audience is primarily from the plant growth community, and this begins the light source part of the program, we will start with a brief description of the discharge lamps. Challenges of economics and of thermal management make lamp efficiency a prime concern in controlled environment agriculture, so we will emphasize science considerations relating to discharge lamp efficiency. We will then look at the spectra and ratings of some representative lighting products, and conclude with a discussion of technological advances.

  9. Pedestal Characterization and Stability of Small-ELM Regimes in NSTX

    SciTech Connect

    Sontag, Aaron C; Canik, John; Maingi, Rajesh; Manickam, J.; Snyder, P.; Bell, R. E.; Gerhardt, S.P.; Kubota, S.; LaBlanc, B. P.; Mueller, D.; Osborne, T.; Tritz, K.

    2010-01-01

    An instability near the plasma edge known as the edge harmonic oscillation (EHO) is thought to enable access to the ELM-free quiescent H-mode (QH-mode) in tokamaks, which is a highly desirable operational regime for ITER because of the avoidance of periodic ELM heat loads. The EHO has been hypothesized to be a saturated kink driven unstable by toroidal rotational shear that provides sufficient transport near the plasma edge to keep the edge plasma below the peeling-ballooning stability limit. NSTX has observed unstable modes with similar characteristics to the EHO coincident with transition to a small-ELM regime (called Type-V). These small ELMs do not have a measurable effect on the plasma stored energy (< 1%). Transition to this regime is associated with a downward biased plasma as evidenced by drsep < -5 mm. Soft x-ray emission indicates that these modes are localized just inside the pedestal and are correlated with increased density fluctuations in the pedestal as measured by microwave reflectometry. The lowest order mode rotates at the plasma rotation frequency, indicating n=1, and harmonics up to n=6 have been observed simultaneously with the n=1, as determined by the rotation frequency of the higher harmonics. Increased edge collisionality is required to access Type-V ELMs. Stability analysis during the observed modes indicates instability to n=1-3 with n=3 having the highest growth rate and unstable mode eigenfunctions peaked near the plasma edge. Discharges with Type-V and Type-I ELMs are both calculated to be on the peeling unstable side of the peeling ballooning stability curve, with the Type-V case at higher normalized pressure gradient.

  10. Siberian Lena River hydrologic regime and recent change

    NASA Astrophysics Data System (ADS)

    Yang, Daqing; Kane, Douglas L.; Hinzman, Larry D.; Zhang, Xuebin; Zhang, Tingjun; Ye, Hengchun

    2002-12-01

    The long-term (1935-1999) monthly records of temperature, precipitation, stream flow, river ice thickness, and active layer depth have been analyzed in this study to examine Lena River hydrologic regime and recent change. Remarkable hydrologic changes have been identified in this study. During the cold season (October-April), significant increases (25-90%) in stream flow and decrease in river ice thickness have been found due to warming in Siberia. In the snowmelt period (May-June), strong warming in spring leads to an advance of snowmelt season into late May and results in a lower daily maximum discharge in June. During summer months (July-September) the changes in stream flow hydrology are less significant in comparison to those for winter and spring seasons. A slight stream flow increase is discovered for both July and August, mainly owing to precipitation increase in May and June. Discharge in September has a slight downward trend due to precipitation decrease and temperature increase in August. The magnitudes of changes in stream flow and river ice thickness identified in this study are large enough to alter the hydrologic regime. Investigation into the hydrologic response of the Lena River to climate change and variation reveals strong linkages of stream flow with temperature and precipitation. We therefore believe that Lena River hydrologic regime changes are mainly the consequence of recent climate warming over Siberia and also closely related to changes in permafrost condition.

  11. Identifying Biologically Relevant Cues in the Hydrologic Regime

    NASA Astrophysics Data System (ADS)

    Lovellford, R. M.; Flitcroft, R.; Santelmann, M. V.; Grant, G. E.; Safeeq, M.; Lewis, S.

    2012-12-01

    Seasonal variation in hydrologic discharge and temperature defines the availability, connectivity, and quality of lentic habitats. Native aquatic species are adapted to local hydrologic regimes , eg. magnitudes and rates of change . In recent decades, biologically relevant hydrologic conditions have been identified that are necessary to maintain habitat conditions for aquatic obligate species. Another element of hydrologic regimes important to aquatic species are the cues that inform individuals of seasonal changes that precipitate important physiological or behavioral alterations. There is a need for hydrologists, biologists, and ecologists, to define biologically significant cues within the hydrologic regime. Coho salmon (Onchorhynchus kisutch), an anadromous species of Pacific salmon, offers an example of sensitivity to environmental cues. Examinations of the run-timing of mature adult coho salmon on the North Umpqua River, OR, indicate that migration timing coincides with decreasing fall water temperatures prior to increasing winter discharge. For this species, adults leave the ocean ready to spawn. Adults need to spawn in small headwater streams prior to the onset of intense storm conditions that prohibit effective deposition or fertilization of eggs in redds (salmon nests).Therefore, the timing of spawning must be carefully executed. Understanding the cues that trigger specific behaviors gives insight to the processes that provide ecosystem stability and flexibility over time. Improved understanding of these cues may help us protect freshwater ecosystems and improve management for endangered species.

  12. Advanced high frequency partial discharge measuring system

    NASA Technical Reports Server (NTRS)

    Karady, George G.

    1994-01-01

    This report explains the Advanced Partial Discharge Measuring System in ASU's High Voltage Laboratory and presents some of the results obtained using the setup. While in operation an insulation is subjected to wide ranging temperature and voltage stresses. Hence, it is necessary to study the effect of temperature on the behavior of partial discharges in an insulation. The setup described in this report can be used to test samples at temperatures ranging from -50 C to 200 C. The aim of conducting the tests described herein is to be able to predict the behavior of an insulation under different operating conditions in addition to being able to predict the possibility of failure.

  13. Cloud regimes as phase transitions

    NASA Astrophysics Data System (ADS)

    Stechmann, Samuel N.; Hottovy, Scott

    2016-06-01

    Clouds are repeatedly identified as a leading source of uncertainty in future climate predictions. Of particular importance are stratocumulus clouds, which can appear as either (i) closed cells that reflect solar radiation back to space or (ii) open cells that allow solar radiation to reach the Earth's surface. Here we show that these clouds regimes -- open versus closed cells -- fit the paradigm of a phase transition. In addition, this paradigm characterizes pockets of open cells as the interface between the open- and closed-cell regimes, and it identifies shallow cumulus clouds as a regime of higher variability. This behavior can be understood using an idealized model for the dynamics of atmospheric water as a stochastic diffusion process. With this new conceptual viewpoint, ideas from statistical mechanics could potentially be used for understanding uncertainties related to clouds in the climate system and climate predictions.

  14. Marine regime shifts: drivers and impacts on ecosystems services

    PubMed Central

    Rocha, J.; Yletyinen, J.; Biggs, R.; Blenckner, T.; Peterson, G.

    2015-01-01

    Marine ecosystems can experience regime shifts, in which they shift from being organized around one set of mutually reinforcing structures and processes to another. Anthropogenic global change has broadly increased a wide variety of processes that can drive regime shifts. To assess the vulnerability of marine ecosystems to such shifts and their potential consequences, we reviewed the scientific literature for 13 types of marine regime shifts and used networks to conduct an analysis of co-occurrence of drivers and ecosystem service impacts. We found that regime shifts are caused by multiple drivers and have multiple consequences that co-occur in a non-random pattern. Drivers related to food production, climate change and coastal development are the most common co-occurring causes of regime shifts, while cultural services, biodiversity and primary production are the most common cluster of ecosystem services affected. These clusters prioritize sets of drivers for management and highlight the need for coordinated actions across multiple drivers and scales to reduce the risk of marine regime shifts. Managerial strategies are likely to fail if they only address well-understood or data-rich variables, and international cooperation and polycentric institutions will be critical to implement and coordinate action across the scales at which different drivers operate. By better understanding these underlying patterns, we hope to inform the development of managerial strategies to reduce the risk of high-impact marine regime shifts, especially for areas of the world where data are not available or monitoring programmes are not in place.

  15. Characterization of thin-film deposition in a pulsed acrylic acid polymerizing discharge

    SciTech Connect

    Voronin, Sergey A.; Bradley, James W.; Fotea, Catalin; Zelzer, Mischa; Alexander, Morgan R.

    2007-07-15

    In this study, thin-film deposition in a pulsed rf polymerizing discharge (13.56 MHz) struck in acrylic acid has been investigated by mass spectrometry, x-ray photoelectron spectroscopy, and quartz crystal microbalance techniques. The experiment was conducted at a fixed acrylic acid pressure of 1.3 Pa and 'on' pulse duration of 0.1 ms, whereas the 'off' time was varied between 0 and 20 ms. The rf input power in the 'on' time and gas flow rate were varied between 10 and 50 W and 1.5 and 4.8 sccm (sccm denotes cubic centimeter per minute at STP), respectively. These changes of the discharge conditions resulted in large-scale progressive variations in film and gas-phase plasma composition. In particular, the -COOH functionality of the monomer was increasingly retained in the plasma-generated thin films as the duty cycle was lowered (i.e., with lowered time-averaged powers). The monomer retention reached its maximum value of 66% for 'off' times exceeding 5 ms, when the discharge was operating in the power-deficient regime. The results show that the film deposition rate is a strong function of the monomer flow rate, whereas -COOH retention is correlated to the amount of unfragmented monomer in the plasma, controlled by the applied power.

  16. Two modes of capacitively coupled rf discharge in CF4

    NASA Astrophysics Data System (ADS)

    Proshina, O. V.; Rakhimova, T. V.; Rakhimov, A. T.; Voloshin, D. G.

    2010-12-01

    Capacitively coupled rf discharge in pure CF4 was studied using a one-dimensional self-consistent particle-in-cell Monte Carlo model. Two different discharge modes are observed depending on the discharge conditions: the regime of electronegative plasma with high-electron temperatures in the bulk, and the regime of electropositive plasma with abnormally low electron temperatures in the bulk. The characteristic features of the two discharge modes are considered. A sharp transition from the former to the latter mode is observed with an increase in applied voltage. The dependence of the transition voltage on gas pressure is analyzed. In the studied range of gas pressures, the existence of a high-temperature mode in an electronegative gas like CF4 is suggested by the balance between the ionization rate and attachment rate in the bulk region. As a result, the transition voltage increases with gas pressure because of the increased relative role of electron attachment. It is shown that the differences in the used electron cross-section sets may noticeably affect the simulation results and the discharge properties. Three different electron cross-section sets for CF4 are considered. In particular, the transition voltage between the two discharge modes differs essentially for different cross-sections used. In order to analyze the fundamental causes of this difference, a detailed comparison of three cross-section sets was done on the basis of the Monte Carlo calculation of swarm parameters in constant electric fields.

  17. Lasik eye surgery - discharge

    MedlinePlus

    ... page: //medlineplus.gov/ency/patientinstructions/000525.htm Lasik eye surgery - discharge To use the sharing features on this page, please enable JavaScript. Lasik eye surgery permanently changes the shape of the cornea ( ...

  18. Electric discharge during electrosurgery.

    PubMed

    Shashurin, Alexey; Scott, David; Zhuang, Taisen; Canady, Jerome; Beilis, Isak I; Keidar, Michael

    2015-01-01

    Electric discharge utilized for electrosurgery is studied by means of a recently developed method for the diagnostics of small-size atmospheric plasma objects based on Rayleigh scattering of microwaves on the plasma volume. Evolution of the plasma parameters in the near-electrode sheaths and in the positive column is measured and analyzed. It is found that the electrosurgical system produces a glow discharge of alternating current with strongly contracted positive column with current densities reaching 10(3) A/cm(2). The plasma electron density and electrical conductivities in the channel were found be 10(16) cm(-3) and (1-2) Ohm(-1) cm(-1), respectively. The discharge interrupts every instance when the discharge-driving AC voltage crosses zero and re-ignites again every next half-wave at the moment when the instant voltage exceeds the breakdown threshold. PMID:25880721

  19. Ventriculoperitoneal shunt - discharge

    MedlinePlus

    ... page: //medlineplus.gov/ency/patientinstructions/000149.htm Ventriculoperitoneal shunt - discharge To use the sharing features on this ... JavaScript. Your child has hydrocephalus and needed a shunt placed to drain excess fluid and relieve pressure ...

  20. Brain radiation - discharge

    MedlinePlus

    Radiation - brain - discharge; Cancer-brain radiation; Lymphoma - brain radiation; Leukemia - brain radiation ... Decadron) while you are getting radiation to the brain. It may make you hungrier, cause leg swelling ...

  1. Eye muscle repair - discharge

    MedlinePlus

    ... page: //medlineplus.gov/ency/patientinstructions/000111.htm Eye muscle repair - discharge To use the sharing features on ... enable JavaScript. You or your child had eye muscle repair surgery to correct eye muscle problems that ...

  2. Carotid artery surgery - discharge

    MedlinePlus

    ... page: //medlineplus.gov/ency/patientinstructions/000238.htm Carotid artery surgery - discharge To use the sharing features on this page, please enable JavaScript. You had carotid artery surgery to restore proper blood flow to your ...

  3. Pneumonia - children - discharge

    MedlinePlus

    ... this page: //medlineplus.gov/ency/patientinstructions/000011.htm Pneumonia in children - discharge To use the sharing features ... this page, please enable JavaScript. Your child has pneumonia, which is an infection in the lungs. In ...

  4. Pneumonia - adults - discharge

    MedlinePlus

    ... this page: //medlineplus.gov/ency/patientinstructions/000017.htm Pneumonia in adults - discharge To use the sharing features on this page, please enable JavaScript. You have pneumonia, which is an infection in your lungs. In ...

  5. Capacitor discharge pulse analysis.

    SciTech Connect

    Baker, Michael Sean; Griffiths, Stewart K.; Tanner, Danelle Mary

    2013-08-01

    Capacitors used in firing sets and other high discharge current applications are discharge tested to verify performance of the capacitor against the application requirements. Parameters such as capacitance, inductance, rise time, pulse width, peak current and current reversal must be verified to ensure that the capacitor will meet the application needs. This report summarizes an analysis performed on the discharge current data to extract these parameters by fitting a second-order system model to the discharge data and using this fit to determine the resulting performance metrics. Details of the theory and implementation are presented. Using the best-fit second-order system model to extract these metrics results in less sensitivity to noise in the measured data and allows for direct extraction of the total series resistance, inductance, and capacitance.

  6. Neck dissection - discharge

    MedlinePlus

    ... page: //medlineplus.gov/ency/patientinstructions/000659.htm Neck dissection - discharge To use the sharing features on this page, please enable JavaScript. Neck dissection is surgery to remove the lymph nodes in ...

  7. Asthma - child - discharge

    MedlinePlus

    ... this page: //medlineplus.gov/ency/patientinstructions/000001.htm Asthma - child - discharge To use the sharing features on ... for your child. Take charge of your child's asthma at home Make sure you know the asthma ...

  8. Electrical discharges in air

    NASA Astrophysics Data System (ADS)

    Antanasijević, R.; Banjanac, R.; Dragić, A.; Joković, D.; Joksimović, D.; Marić, Z.; Panić, B.; Udovičić, V.; Vigier, J. P.

    2002-12-01

    An experiment on electrical discharges in air under normal atmospheric conditions has been performed. The ratio between output and input energy is greater than 1, which confirms the results already reported by Graneau et al.

  9. Simulation study of one-dimensional self-organized pattern in an atmospheric-pressure dielectric barrier discharge

    SciTech Connect

    Zhang, Jiao; Wang, Yanhui Wang, Dezhen

    2015-04-15

    A two-dimensional fluid model is developed to simulate the one-dimensional self-organized patterns in an atmospheric-pressure dielectric barrier discharge (DBD) driven by sinusoidal voltage in argon. Under certain conditions, by changing applied voltage amplitude, the transversely uniform discharge can evolve into the patterned discharge and the varied self-organized patterned discharges with different numbers and arrangements of discharge channels can be observed. Similar to the uniform atmospheric-pressure DBD, the patterned discharge mode is found to undergo a transition from Townsend regime, sub-glow regime to glow regime with increasing applied voltage amplitude. In the different regimes, charged particles and electric field display different dynamical behaviors. If the voltage amplitude is increased over a certain value, the discharge enters an asymmetric patterned discharge mode, and then transforms into the spatially chaotic state with out-of-order discharge channels. The reason for forming the one-dimensional self-organized pattern is mainly due to the so-called activation-inhibition effect resulting from the local high electron density region appearing in discharge space. Electrode arrangement is the reason that induces local high electron density.

  10. Discharges for lighting

    NASA Astrophysics Data System (ADS)

    Stoffels, W. W.; Nimalasuriya, T.; Flikweert, A. J.; Mulders, H. C. J.

    2007-12-01

    The most common man-made discharge is a lamp. Even though lamps are often considered a mature technology, the discharge physics is often poorly understood. Two recent initiatives discussed here show that plasma research can help to make significant improvements. First we discuss color separation in metal halide lamps, which is a problem that prevents these highly efficient lamps from being used in more applications. Secondly a novel lamp concept is presented that may replace the current mercury based fluorescent lamps.

  11. Low partial discharge vacuum feedthrough

    NASA Technical Reports Server (NTRS)

    Benham, J. W.; Peck, S. R.

    1979-01-01

    Relatively discharge free vacuum feedthrough uses silver-plated copper conductor jacketed by carbon filled silicon semiconductor to reduce concentrated electric fields and minimize occurrence of partial discharge.

  12. The effect of refrigerants in the mixed lubrication regime

    SciTech Connect

    Mizuhara, Kazuyuki; Tomimoto, Makoto

    1997-12-31

    Because of environmental concerns, CFC (chlorofluorocarbon) refrigerants must be replaced with HFCs (hydrofluorocarbons). As a result, many tribological problems are caused especially in rotary piston compressors. To solve the problem, the effects of refrigerants on friction and wear characteristics of the oil and refrigerant mixtures at the mixed lubrication regime are investigated. The difference in refrigerants are clearly observed not only in boundary but also in the mixed lubrication regime. The effects of operating conditions on sliding conditions and experimental results are also discussed. It is concluded that for practical application where long life is essential, experiments must be conducted under the mixed lubrication regime. Also, the importance of defining the lubrication regime in terms of film parameter is emphasized.

  13. Influence of the voltage waveform during nanocomposite layer deposition by aerosol-assisted atmospheric pressure Townsend discharge

    NASA Astrophysics Data System (ADS)

    Profili, J.; Levasseur, O.; Naudé, N.; Chaneac, C.; Stafford, L.; Gherardi, N.

    2016-08-01

    This work examines the growth dynamics of TiO2-SiO2 nanocomposite coatings in plane-to-plane Dielectric Barrier Discharges (DBDs) at atmospheric pressure operated in a Townsend regime using nebulized TiO2 colloidal suspension in hexamethyldisiloxane as the growth precursors. For low-frequency (LF) sinusoidal voltages applied to the DBD cell, with voltage amplitudes lower than the one required for discharge breakdown, Scanning Electron Microscopy of silicon substrates placed on the bottom DBD electrode reveals significant deposition of TiO2 nanoparticles (NPs) close to the discharge entrance. On the other hand, at higher frequencies (HF), the number of TiO2 NPs deposited strongly decreases due to their "trapping" in the oscillating voltage and their transport along the gas flow lines. Based on these findings, a combined LF-HF voltage waveform is proposed and used to achieve significant and spatially uniform deposition of TiO2 NPs across the whole substrate surface. For higher voltage amplitudes, in the presence of hexamethyldisiloxane and nitrous oxide for plasma-enhanced chemical vapor deposition of inorganic layers, it is found that TiO2 NPs become fully embedded into a silica-like matrix. Similar Raman spectra are obtained for as-prepared TiO2 NPs and for nanocomposite TiO2-SiO2 coating, suggesting that plasma exposure does not significantly alter the crystalline structure of the TiO2 NPs injected into the discharge.

  14. Impact of river discharge on phytoplankton bloom dynamics in eutrophic estuaries: A model study

    NASA Astrophysics Data System (ADS)

    Liu, Bo; de Swart, Huib E.

    2015-12-01

    Field observations in estuaries reveal that phytoplankton blooms are strongly affected by advection processes related to river flow. To gain quantitative insight into this dependence, experiments were performed with a new idealised model that couples physical and biological processes. Advection of phytoplankton and nutrient by subtidal flow was explicitly accounted for, as well as longitudinal and vertical mixing processes. Results show that the idealised model is capable of reproducing the observed bloom. The specific spatial distribution of phytoplankton population emerges because the latter is suppressed in the upper reach by the advection processes, and the growth is limited in the lower reach by low nutrient concentrations. A sensitivity study of model results to different river discharges reveals the presence of three regimes. In the low discharge regime, blooms form because growth is faster than decay due to advection processes. In the high discharge regime, the situation is opposite and no blooms form. If time scales of growth and advection are comparable (in moderate discharge regime), phytoplankton population increases significantly slower compared to the low discharge regime. Results of additional model runs, in which water depth and the e-folding length scale of estuarine width convergence were varied, revealed that the three regimes occur in all these cases.

  15. The future is upon us -- Zero discharge

    SciTech Connect

    Goodrich, W.G.; Lewis, K.G.

    1996-08-01

    Early in the operation of a zero discharge water treatment system, which reclaims paper mill effluent to provide cooling tower makeup for a power plant, effects from the organic loading in the influent prevented operation of the Reverse Osmosis (RO) Units and hampered operation of Clarifier/Softeners, Brine Concentrators and a Crystallizer. Solutions implemented to remediate the problems included front-end treatment of the influent to improve oxidation and coagulation, down-stream nano-filtration of the wastewater to facilitate RO operation, and back-end charge neutralization and variation of the total dissolved solids (TDS) to organics ratio to improve crystallizer operation.

  16. Dynamic regimes of random fuzzy logic networks

    NASA Astrophysics Data System (ADS)

    Wittmann, Dominik M.; Theis, Fabian J.

    2011-01-01

    Random multistate networks, generalizations of the Boolean Kauffman networks, are generic models for complex systems of interacting agents. Depending on their mean connectivity, these networks exhibit ordered as well as chaotic behavior with a critical boundary separating both regimes. Typically, the nodes of these networks are assigned single discrete states. Here, we describe nodes by fuzzy numbers, i.e. vectors of degree-of-membership (DOM) functions specifying the degree to which the nodes are in each of their discrete states. This allows our models to deal with imprecision and uncertainties. Compatible update rules are constructed by expressing the update rules of the multistate network in terms of Boolean operators and generalizing them to fuzzy logic (FL) operators. The standard choice for these generalizations is the Gödel FL, where AND and OR are replaced by the minimum and maximum of two DOMs, respectively. In mean-field approximations we are able to analytically describe the percolation and asymptotic distribution of DOMs in random Gödel FL networks. This allows us to characterize the different dynamic regimes of random multistate networks in terms of FL. In a low-dimensional example, we provide explicit computations and validate our mean-field results by showing that they agree well with network simulations.

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

    SciTech Connect

    Liu, Fu-cheng; Yan, Wen; Wang, De-zhen

    2013-12-15

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

  18. Influence of voltage pulse width on the discharge characteristics in an atmospheric dielectric-barrier-discharge plasma jet

    NASA Astrophysics Data System (ADS)

    Uchida, Giichiro; Takenaka, Kosuke; Setsuhara, Yuichi

    2016-01-01

    We present here the analysis of the discharge characteristics of a He dielectric-barrier-discharge (DBD) plasma jet operated in the voltage duty ratio of 20 to 80% under the condition of driving voltage frequency 5 kHz. Discharge strength is sensitive to the voltage pulse width, and the pulse width of 70 µs, which corresponds to the duty ratio of 35%, leads to high O optical emission intensity. We also performed time-resolved optical emission measurements in a transient pulse discharge driven by various voltage duty ratios. Two distinct pulse discharges are observed in the rising and falling periods of the positive rectangular voltage, and the first and second discharges have a peak intensity of optical emission at different duty ratio. The observations indicate that an adequate voltage pulse width could ignite a strong discharge both in the rising and falling period of applied voltage, which could produce a large amount of reactive excited O atoms.

  19. Determining the microwave coupling and operational efficiencies of a microwave plasma assisted chemical vapor deposition reactor under high pressure diamond synthesis operating conditions

    SciTech Connect

    Nad, Shreya; Gu, Yajun; Asmussen, Jes

    2015-07-15

    The microwave coupling efficiency of the 2.45 GHz, microwave plasma assisted diamond synthesis process is investigated by experimentally measuring the performance of a specific single mode excited, internally tuned microwave plasma reactor. Plasma reactor coupling efficiencies (η) > 90% are achieved over the entire 100–260 Torr pressure range and 1.5–2.4 kW input power diamond synthesis regime. When operating at a specific experimental operating condition, small additional internal tuning adjustments can be made to achieve η > 98%. When the plasma reactor has low empty cavity losses, i.e., the empty cavity quality factor is >1500, then overall microwave discharge coupling efficiencies (η{sub coup}) of >94% can be achieved. A large, safe, and efficient experimental operating regime is identified. Both substrate hot spots and the formation of microwave plasmoids are eliminated when operating within this regime. This investigation suggests that both the reactor design and the reactor process operation must be considered when attempting to lower diamond synthesis electrical energy costs while still enabling a very versatile and flexible operation performance.

  20. Determining the microwave coupling and operational efficiencies of a microwave plasma assisted chemical vapor deposition reactor under high pressure diamond synthesis operating conditions.

    PubMed

    Nad, Shreya; Gu, Yajun; Asmussen, Jes

    2015-07-01

    The microwave coupling efficiency of the 2.45 GHz, microwave plasma assisted diamond synthesis process is investigated by experimentally measuring the performance of a specific single mode excited, internally tuned microwave plasma reactor. Plasma reactor coupling efficiencies (η) > 90% are achieved over the entire 100-260 Torr pressure range and 1.5-2.4 kW input power diamond synthesis regime. When operating at a specific experimental operating condition, small additional internal tuning adjustments can be made to achieve η > 98%. When the plasma reactor has low empty cavity losses, i.e., the empty cavity quality factor is >1500, then overall microwave discharge coupling efficiencies (η(coup)) of >94% can be achieved. A large, safe, and efficient experimental operating regime is identified. Both substrate hot spots and the formation of microwave plasmoids are eliminated when operating within this regime. This investigation suggests that both the reactor design and the reactor process operation must be considered when attempting to lower diamond synthesis electrical energy costs while still enabling a very versatile and flexible operation performance. PMID:26233399

  1. Determining the microwave coupling and operational efficiencies of a microwave plasma assisted chemical vapor deposition reactor under high pressure diamond synthesis operating conditions

    NASA Astrophysics Data System (ADS)

    Nad, Shreya; Gu, Yajun; Asmussen, Jes

    2015-07-01

    The microwave coupling efficiency of the 2.45 GHz, microwave plasma assisted diamond synthesis process is investigated by experimentally measuring the performance of a specific single mode excited, internally tuned microwave plasma reactor. Plasma reactor coupling efficiencies (η) > 90% are achieved over the entire 100-260 Torr pressure range and 1.5-2.4 kW input power diamond synthesis regime. When operating at a specific experimental operating condition, small additional internal tuning adjustments can be made to achieve η > 98%. When the plasma reactor has low empty cavity losses, i.e., the empty cavity quality factor is >1500, then overall microwave discharge coupling efficiencies (ηcoup) of >94% can be achieved. A large, safe, and efficient experimental operating regime is identified. Both substrate hot spots and the formation of microwave plasmoids are eliminated when operating within this regime. This investigation suggests that both the reactor design and the reactor process operation must be considered when attempting to lower diamond synthesis electrical energy costs while still enabling a very versatile and flexible operation performance.

  2. Control of the UV flux of a XeCl dielectric barrier discharge excilamp through its current variation

    SciTech Connect

    Piquet, H; Bhosle, S; Diez, R; Cousineau, M; Djibrillah, M; Le Thanh, D; Dagang, A N; Zissis, G

    2012-02-28

    The efficiency of the electrical power transfer to the gas mixture of a XeCl dielectric barrier discharge (DBD) exciplex lamp is analysed. An equivalent circuit model of the DBD is considered. It is shown that the excilamp power can be controlled by applying current to the lamp. This highly desired property is ensured by means of a specific power supply topology, whose concepts and design are discussed. The experimental prototype of a current-mode converter operating in the pulsed regime at pulse repetition rate of 50 kHz is presented and its capability to control the amount of energy transferred during each current pulse is demonstrated. The capability of this power supply to maintain specific operating conditions for the DBD lamp, with a very stable behaviour (even at a very low current, in the regime of a single discharge channel), is illustrated. The experimental results of a combined use of this converter and a XeCl excilamp are presented. The influence of the supply parameters on the 308-nm XeCl excilamp is analysed. The shape of the UV pulse of the lamp is experimentally shown to be similar to that of the current, which actually flows into the gas mixture. The UV radiation power is demonstrated to be tightly correlated to the current injected into the gas and controlled by the available degrees of freedom offered by the power supply. The measured UV output characteristics and performance of the system are discussed. Time resolved UV imaging of a XeCl DBD excilamp is used to analyse the mechanisms involved in the production of exciplexes at various power supply regimes. It is shown that a pulsed voltage source leads to formation of short high intensity UV peaks, while current pulses lead to formation of sustained discharge filaments. Based on the results of modelling of the above-mentioned operation conditions, the two power supply regimes are compared and analysed from the point of view of the UV power and radiative control.

  3. 2D gasdynamic simulation of the kinetics of an oxygen-iodine laser with electric-discharge generation of singlet oxygen

    SciTech Connect

    Chukalovsky, A. A.; Rakhimova, T. V.; Klopovsky, K. S.; Mankelevich, Yu. A.; Proshina, O. V.

    2011-03-15

    The kinetic processes occurring in an electric-discharge oxygen-iodine laser are analyzed with the help of a 2D (r, z) gasdynamic model taking into account transport of excited oxygen, singlet oxygen, and radicals from the electric discharge and their mixing with the iodine-containing gas. The main processes affecting the dynamics of the gas temperature and gain are revealed. The simulation results obtained using the 2D model agree well with the experimental data on the mixture gain. A subsonic oxygen-iodine laser in which singlet oxygen is generated by a 350 W transverse RF discharge excited in an oxygen flow at a pressure P = 10 Torr and the discharge tube wall is covered with mercury oxide is simulated. The simulated mixing system is optimized in terms of the flow rate and the degree of preliminary dissociation of the iodine flow. The optimal regime of continuous operation of a subsonic electric-discharge oxygen-iodine laser is found.

  4. Plasma regimes in high power pulsed magnetron sputtering

    NASA Astrophysics Data System (ADS)

    de Los Arcos, Teresa

    2013-09-01

    High Power Pulsed Magnetron Sputtering (HPPMS) is a relatively recent variation of magnetron sputtering where high power is applied to the magnetron in short pulses. The result is the formation of dense transient plasmas with a high fraction of ionized species, ideally leading to better control of film growth through substrate bias. However, the broad range of experimental conditions accessible in pulsed discharges results in bewildering variations in current and voltage pulse shapes, pulse power densities, etc, which represent different discharge behaviors, making it difficult to identify relevant deposition conditions. The complexity of the plasma dynamics is evident. Within each pulse, plasma characteristics such as plasma composition, density, gas rarefaction, spatial distribution, degree of self-sputtering, etc. vary with time. A recent development has been the discovery that the plasma emission can self-organize into well-defined regions of high and low plasma emissivity above the racetrack (spokes), which rotate in the direction given by the E ×B drift and that significantly influence the transport mechanisms in HPPMS. One seemingly universal characteristic of HPPMS plasmas is the existence of well defined plasma regimes for different power ranges. These regimes are clearly differentiated in terms of plasma conductivity, plasma composition and spatial plasma self-organization. We will discuss the global characteristics of these regimes in terms of current-voltage characteristics, energy-resolved QMS and OES analysis, and fast imaging. In particular we will discuss how the reorganization of the plasma emission into spokes is associated only to specific regimes of high plasma conductivity. We will also briefly discuss the role of the target in shaping the characteristics of the HPPMS plasma, since sputtering is a surface-driven process. This work was supported by the Deutsche Forschungsgemeinschaft (DFG) within the framework of the SFB-TR87.

  5. High Power ECR Ion Thruster Discharge Characterization

    NASA Technical Reports Server (NTRS)

    Foster, John E.; Kamhawi, Hani; Haag, Thomas; Carpenter, Christian; Williams, George W.

    2006-01-01

    Electron cyclotron resonance (ECR) based ion thrusters with carbon based ion optics can potentially satisfy lifetime requirements for long duration missions (approximately 10 years) because grid erosion and cathode insert depletion issues are virtually eliminated. Though the ECR plasma discharge has been found to typically operate at slightly higher discharge losses than conventional DC ion thrusters (for high total thruster power applications), the discharge power fraction is small (less than 1 percent at 25 kW). In this regard, the benefits of increased life, low discharge plasma potentials, and reduced complexity are welcome tradeoffs for the associated discharge efficiency decrease. Presented here are results from discharge characterization of a large area ECR plasma source for gridded ion thruster applications. These measurements included load matching efficacy, bulk plasma properties via Langmuir probe, and plasma uniformity as measured using current probes distributed at the exit plane. A high degree of plasma uniformity was observed (flatness greater than 0.9). Additionally, charge state composition was qualitatively evaluated using emission spectroscopy. Plasma induced emission was dominated by xenon ion lines. No doubly charged xenon ions were detected.

  6. Monitor For Electrical-Discharge Machining

    NASA Technical Reports Server (NTRS)

    Burley, Richard K.

    1993-01-01

    Circuit monitors electrical-discharge-machining (EDM) process to detect and prevent abnormal arcing, which can produce unacceptable "burn" marks on workpiece. When voltage between EDM electrode and workpiece behaves in manner indicative of abnormal arcing, relay made to switch off EDM power, which remains off until operator attends to EDM setup and resets monitor.

  7. Production of runaway electrons by negative streamer discharges

    NASA Astrophysics Data System (ADS)

    Chanrion, O.; Neubert, T.

    2010-06-01

    In this paper we estimate the probability that cold electrons can be accelerated by an ambient electric field into the runaway regime, and discuss the implications for negative streamer formation. The study is motivated by the discovery of ms duration bursts of γ-rays from the atmosphere above thunderstorms, the so-called Terrestrial Gamma-Ray Flashes. The radiation is thought to be bremsstrahlung from energetic (MeV) electrons accelerated in a thunderstorm discharge. The observation goes against conventional wisdom that discharges in air are carried by electrons with energies below a few tens of eV. Instead the relativistic runaway electron discharge has been proposed which requires a lower threshold electric field; however, seed electrons must be born with energies in the runaway regime. In this work we study the fundamental problem of electron acceleration in a conventional discharge and the conditions on the electric field for the acceleration of electrons into the runaway regime. We use particle codes to describe the process of stochastic acceleration and introduce a novel technique that improves the statistics of the relatively few electrons that reach high energies. The calculation of probabilities for electrons to reach energies in the runaway regime shows that even with modest fields, electrons can be energized in negative streamer tips into the runaway regime, creating a beamed distribution in front of the streamer that affects its propagation. The results reported here suggest that theories of negative streamers and spark propagation should be reexamined with an improved characterization of the kinetic effects of electrons.

  8. 2D fluid simulations of discharges at atmospheric pressure in reactive gas mixtures

    NASA Astrophysics Data System (ADS)

    Bourdon, Anne

    2015-09-01

    Since a few years, low-temperature atmospheric pressure discharges have received a considerable interest as they efficiently produce many reactive chemical species at a low energy cost. This potential is of great interest for a wide range of applications as plasma assisted combustion or biomedical applications. Then, in current simulations of atmospheric pressure discharges, there is the need to take into account detailed kinetic schemes. It is interesting to note that in some conditions, the kinetics of the discharge may play a role on the discharge dynamics itself. To illustrate this, we consider the case of the propagation of He-N2 discharges in long capillary tubes, studied for the development of medical devices for endoscopic applications. Simulation results put forward that the discharge dynamics and structure depend on the amount of N2 in the He-N2 mixture. In particular, as the amount of N2 admixture increases, the discharge propagation velocity in the tube increases, reaches a maximum for about 0 . 1 % of N2 and then decreases, in agreement with experiments. For applications as plasma assisted combustion with nanosecond repetitively pulsed discharges, there is the need to handle the very different timescales of the nanosecond discharge with the much longer (micro to millisecond) timescales of combustion processes. This is challenging from a computational point of view. It is also important to better understand the coupling of the plasma induced chemistry and the gas heating. To illustrate this, we present the simulation of the flame ignition in lean mixtures by a nanosecond pulsed discharge between two point electrodes. In particular, among the different discharge regimes of nanosecond repetitively pulsed discharges, a ``spark'' regime has been put forward in the experiments, with an ultra-fast local heating of the gas. For other discharge regimes, the gas heating is much weaker. We have simulated the nanosecond spark regime and have observed shock waves

  9. (Gas discharges and applications)

    SciTech Connect

    Sauers, I.

    1988-10-04

    The traveler attended the Ninth International Conference on Gas Discharges and Their Applications, which was held in Venice, Italy, on September 19--23, 1988; presented two papers, (1) Ion Chemistry in SF{sub 6} Corona'' and (2) Production of S{sub 2}F{sub 10} by SF{sub 6} Spark Discharge''; and participated in numerous discussions with conference participants on gas discharges related to his work on SF{sub 6}. The traveler visited the Centre de Physique Atomique at the University Paul Sabatier in Toulouse, France, to discuss with Dr. J. Casanovas his work on SF{sub 6} decomposition. Following that visit, the traveler visited the Laboratoire de Photoelectricite at the University of Dijon to discuss with Dr. J.-P. Goudonnet his work on surface studies and on the use of tunneling electron spectroscopy for the chemical analysis of surfaces.

  10. Study of the synchronous operation of an Annular Field Reversed Configuration plasma device

    NASA Astrophysics Data System (ADS)

    Kirtley, David E.

    Field Reversed Configuration (FRC) plasmas are high-density, magnetized, pulsed plasmas with unique translational and efficient formation properties that lend themselves to many uses. This dissertation furthers the understanding and empirical investigations into a slow-formation FRC, the low-voltage Annular Field Reversed Configuration plasma (AFRC) by successfully operating with heavy gases, at low-voltages, and in a synchronous discharge configuration. The AFRC plasma is an evolution of the cylindrical shock compression driven FRC that aims to increase compression times well into diffusive timescales, thereby increasing overall plasma content, lifetime, and greatly simplifying pulsed switching and transmission hardware. AFRC plasmas have uses ranging from primary pulsed magnetic fusion, refueling for Tokamak plasmas, and advanced space propulsion. In this thesis it is shown that AFRCs operating in a synchronous discharge configuration generate efficient, high-density magnetized toroidal plasmas with clear transitional regimes and optimal discharge parameters. A 10-kJ pulsed power facility and discharge network was constructed to explore AFRC plasmas. An extensive array of pulsed diagnostics were developed to explore the operational characteristics of a 40-cm outer diameter annular theta pinch and its pre-ionization, compression, field reversal, and translation configurations. Twelve high-speed, 3-axis B-dot probes were used to show plasma magnetization and compression for various discharge geometries. A fast DICAM and wide-angle photometer examined overall plasma content, compression regimes, downstream translation, and plasma instabilities for argon and xenon discharges ranging from 3--20 mTorr, 500--1000 V, and 185--450 mus discharge periods. Downstream B-dot probes and collimated, amplified photometers examined downstream plasma translation and magnetization. An axially-scanning internal triple probe was utilized to measure temporal plasma temperature, density

  11. Experimental evaluation of the performance of the sodium metal chloride battery below usual operating temperatures

    NASA Astrophysics Data System (ADS)

    Gerovasili, Eirini; May, Johanna F.; Sauer, Dirk Uwe

    2014-04-01

    The high operating temperature of the sodium metal chloride battery limits the possible applications of this storage technology. In this study, the performance of a 3.65 kWh (80 Ah, 48 V) battery at temperatures as low as 240 °C is measured and the efficiency at different discharge currents, cycling frequencies and operating temperatures is examined. The total available capacity of a 40 Ah string at 240 °C when discharging with 0.1C is found to be just 1 Ah smaller compared to 275 °C, which is the nominal operating temperature of the battery. However it is shown that low temperatures have a big impact on the charge duration. Starting from 20% SOC (state-of-charge) the duration of charging until the fulfillment of the end-of-charge criterion at 240 °C is 25 h with the quickest charging regime (0.25C, 2.7 V/cell) whereas until 90% SOC 7.6 h are required. At a limited SOC operation window from 20% to 90% the total daily efficiency of the 3.65 kWh battery is higher at 240 °C compared to 275 °C and increases from 69% if one cycle is performed daily with 0.175C discharge current to 81% for two cycles with the same discharge rate.

  12. Deterministic-random separation in nonstationary regime

    NASA Astrophysics Data System (ADS)

    Abboud, D.; Antoni, J.; Sieg-Zieba, S.; Eltabach, M.

    2016-02-01

    In rotating machinery vibration analysis, the synchronous average is perhaps the most widely used technique for extracting periodic components. Periodic components are typically related to gear vibrations, misalignments, unbalances, blade rotations, reciprocating forces, etc. Their separation from other random components is essential in vibration-based diagnosis in order to discriminate useful information from masking noise. However, synchronous averaging theoretically requires the machine to operate under stationary regime (i.e. the related vibration signals are cyclostationary) and is otherwise jeopardized by the presence of amplitude and phase modulations. A first object of this paper is to investigate the nature of the nonstationarity induced by the response of a linear time-invariant system subjected to speed varying excitation. For this purpose, the concept of a cyclo-non-stationary signal is introduced, which extends the class of cyclostationary signals to speed-varying regimes. Next, a "generalized synchronous average'' is designed to extract the deterministic part of a cyclo-non-stationary vibration signal-i.e. the analog of the periodic part of a cyclostationary signal. Two estimators of the GSA have been proposed. The first one returns the synchronous average of the signal at predefined discrete operating speeds. A brief statistical study of it is performed, aiming to provide the user with confidence intervals that reflect the "quality" of the estimator according to the SNR and the estimated speed. The second estimator returns a smoothed version of the former by enforcing continuity over the speed axis. It helps to reconstruct the deterministic component by tracking a specific trajectory dictated by the speed profile (assumed to be known a priori).The proposed method is validated first on synthetic signals and then on actual industrial signals. The usefulness of the approach is demonstrated on envelope-based diagnosis of bearings in variable

  13. SPECIAL ISSUE DEVOTED TO THE 80TH ANNIVERSARY OF ACADEMICIAN N G BASOV'S BIRTH: Repetitively pulsed X-ray laser operating on the 3p — 3s transition of the Ne-like argon in a capillary discharge

    NASA Astrophysics Data System (ADS)

    Vinogradov, Aleksandr V.; Rocca, J. J.

    2003-01-01

    The paper is devoted to a 469-Å X-ray laser excited by a fast capillary discharge in neon. The basic characteristics of the active medium and laser beam are presented. Applications of the laser in the studies of plasmas with densities of up to 1020 cm-3, in interferometry, reflectometry, for analysis of materials, etc. are described. A brief historical review is presented and the current state of the art in the development of laboratory X-ray lasers is considered.

  14. Optics in the Relativistic Regime

    NASA Astrophysics Data System (ADS)

    Tajima, Toshiki

    2012-06-01

    Optics has extended the frontier of low energy physics. Here we present the progress in the opposite direction of relativistic intensity regime of optics. With intense and large energy laser, particles may be accelerated to high energies via laser wakefield acceleration (Tajima and Dawson, 1979) over a compact distance orders of magnitude shorter than the RF approach. We should be able to accelerate electrons (over 30m) and ions (over cm) toward TeV with an existing kJ laser. We can check Lorentz invariance in the ultrarelativistic regime. Further, laser allows us to explore the presence of weakly coupling fields such as Dark Matter and Dark Energy with an unprecedented sensitivity. We call this emerging capability as the Laser Particle Physics Paradigm (LP^3).

  15. Demystifying optimal dynamic treatment regimes.

    PubMed

    Moodie, Erica E M; Richardson, Thomas S; Stephens, David A

    2007-06-01

    A dynamic regime is a function that takes treatment and covariate history and baseline covariates as inputs and returns a decision to be made. Murphy (2003, Journal of the Royal Statistical Society, Series B 65, 331-366) and Robins (2004, Proceedings of the Second Seattle Symposium on Biostatistics, 189-326) have proposed models and developed semiparametric methods for making inference about the optimal regime in a multi-interval trial that provide clear advantages over traditional parametric approaches. We show that Murphy's model is a special case of Robins's and that the methods are closely related but not equivalent. Interesting features of the methods are highlighted using the Multicenter AIDS Cohort Study and through simulation. PMID:17688497

  16. The emerging climate change regime

    SciTech Connect

    Bodansky, D.M.

    1995-11-01

    The emerging climate change regime--with the UN Framework Convention on Climate Change (FCCC) at its core--reflects the substantial uncertainties, high stakes and complicated politics of the greenhouse warming issue. The regime represents a hedging strategy. On the one hand, it treats climate change as a potentially serious problem, and in response, creates a long-term, evolutionary process to encourage further research, promote national planning, increase public awareness, and help create a sense of community among states. But it requires very little by way of substantive--and potentially costly--mitigation or adaptation measures. Although the FCCC parties have agreed to negotiate additional commitments, substantial progress is unlikely without further developments in science, technology, and public opinion. The FCCC encourages such developments, and is capable of evolution and growth, should the political will to take stronger international action emerge. 120 refs., 3 tabs.

  17. The International Climate Change Regime

    NASA Astrophysics Data System (ADS)

    Yamin, Farhana; Depledge, Joanna

    2005-01-01

    Aimed at the increasing number of policy-makers, stakeholders, researchers, and other professionals working on climate change, this volume presents a detailed description and analysis of the international regime established in 1992 to combat the threat of global climate change. It provides a comprehensive accessible guide to a high-profile area of international law and politics, covering not only the obligations and rights of countries, but ongoing climate negotiations as well.

  18. Hall effect in hopping regime

    NASA Astrophysics Data System (ADS)

    Avdonin, A.; Skupiński, P.; Grasza, K.

    2016-02-01

    A simple description of the Hall effect in the hopping regime of conductivity in semiconductors is presented. Expressions for the Hall coefficient and Hall mobility are derived by considering averaged equilibrium electron transport in a single triangle of localization sites in a magnetic field. Dependence of the Hall coefficient is analyzed in a wide range of temperature and magnetic field values. Our theoretical result is applied to our experimental data on temperature dependence of Hall effect and Hall mobility in ZnO.

  19. 46 CFR 153.964 - Discharge by gas pressurization.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Discharge by gas pressurization. 153.964 Section 153.964... CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Operations Cargo Transfer Procedures § 153.964 Discharge by gas pressurization. The person in charge of cargo transfer may...

  20. 33 CFR 157.31 - Discharges: Chemical additives.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Discharges: Chemical additives. 157.31 Section 157.31 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY... OIL IN BULK Vessel Operation § 157.31 Discharges: Chemical additives. No person may use a...

  1. 33 CFR 157.31 - Discharges: Chemical additives.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Discharges: Chemical additives. 157.31 Section 157.31 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY... OIL IN BULK Vessel Operation § 157.31 Discharges: Chemical additives. No person may use a...

  2. 33 CFR 157.31 - Discharges: Chemical additives.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Discharges: Chemical additives. 157.31 Section 157.31 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY... OIL IN BULK Vessel Operation § 157.31 Discharges: Chemical additives. No person may use a...

  3. 33 CFR 157.31 - Discharges: Chemical additives.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Discharges: Chemical additives. 157.31 Section 157.31 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY... OIL IN BULK Vessel Operation § 157.31 Discharges: Chemical additives. No person may use a...

  4. 33 CFR 157.31 - Discharges: Chemical additives.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Discharges: Chemical additives. 157.31 Section 157.31 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY... OIL IN BULK Vessel Operation § 157.31 Discharges: Chemical additives. No person may use a...

  5. 46 CFR 153.966 - Discharge by liquid displacement.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Discharge by liquid displacement. 153.966 Section 153... SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Operations Cargo Transfer Procedures § 153.966 Discharge by liquid displacement. The person in charge of cargo transfer...

  6. 46 CFR 153.966 - Discharge by liquid displacement.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Discharge by liquid displacement. 153.966 Section 153... SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Operations Cargo Transfer Procedures § 153.966 Discharge by liquid displacement. The person in charge of cargo transfer...

  7. 46 CFR 153.966 - Discharge by liquid displacement.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Discharge by liquid displacement. 153.966 Section 153... SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Operations Cargo Transfer Procedures § 153.966 Discharge by liquid displacement. The person in charge of cargo transfer...

  8. 46 CFR 153.966 - Discharge by liquid displacement.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Discharge by liquid displacement. 153.966 Section 153... SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Operations Cargo Transfer Procedures § 153.966 Discharge by liquid displacement. The person in charge of cargo transfer...

  9. 46 CFR 153.966 - Discharge by liquid displacement.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Discharge by liquid displacement. 153.966 Section 153... SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Operations Cargo Transfer Procedures § 153.966 Discharge by liquid displacement. The person in charge of cargo transfer...

  10. 46 CFR 153.964 - Discharge by gas pressurization.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Discharge by gas pressurization. 153.964 Section 153.964... CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Operations Cargo Transfer Procedures § 153.964 Discharge by gas pressurization. The person in charge of cargo transfer may...

  11. 46 CFR 153.964 - Discharge by gas pressurization.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Discharge by gas pressurization. 153.964 Section 153.964 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Operations Cargo Transfer Procedures § 153.964 Discharge by...

  12. 46 CFR 153.964 - Discharge by gas pressurization.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Discharge by gas pressurization. 153.964 Section 153.964... CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Operations Cargo Transfer Procedures § 153.964 Discharge by gas pressurization. The person in charge of cargo transfer may...

  13. Low Pressure Experimental Simulation of Electrical Discharges Above and Inside a Cloud

    NASA Technical Reports Server (NTRS)

    Jarzembski, Maurice A.; Srivastava, Vandana

    1996-01-01

    A low pressure laboratory experiment to generate sporadic electrical discharges in either a particulate dielectric or air, representing a competing path of preferred electrical breakdown, was investigated. At high pressures, discharges occurred inside the dielectric particulate; at low pressures, discharges occurred outside the dielectric particulate; at a transition pressure regime, which depends on conductivity of the dielectric particulate, discharges were simultaneously generated in both particulate dielectric and air. Unique use of a particulate dielectric was critical for sporadic discharges at lower pressures which were not identical in character to discharges without the particulate dielectric. Application of these experimental results to the field of atmospheric electricity and simulation of the above-cloud type discharges that have recently been documented, called jets and sprites, are discussed.

  14. The impact of climate change on Fantanele reservoir operating rules

    NASA Astrophysics Data System (ADS)

    Dumitrache, Ramona; Galie, Andreea-Cristina

    2014-05-01

    The FP 7 research project ECLISE - Enabling Climate Information Service for Europe has the overall objective to develop an European service that meets the needs of climate information of the Member States of the European Union. In this project, four major areas of impact (cities, coasts, water and energy) are analysed. This paper presents the results of the climate change impact on a reservoir with hydropower use. A case study, for a Romanian reservoir (Fantanele reservoir located on the Somes River corresponding to Mariselu hydropower station), was performed. The operating curves/rules, relying on the monthly average discharges, were designed for current state. The modified discharges derived from hydrological model that assumed four climate models (CNRM_RM5.1_ARPEGE (A), HC_HadRM3Q0_HadCM3Q0 (B), SMHI_RCA3_BCM (C), SMHI_RCA3_ECHAM5 (D)) for future water resources estimation were used to design the modified operating rules in case of climate change. Operation lines in assured regime were determined using "Water Supplies - Demand" balance. The water balance has been achieved, in the cross-section of the Fantanele dam, as difference between natural inflow into the lake and regulated discharge for every 30 years, for each month, of the years 2020-2050, respectively for each of the four cases. In order to assess the future turbinated discharge, needed to be used for the design of future operation rules, the regulated discharges were determined for each month and for each of the four cases, applying graphical - analytical method called "wire stretched". Further, a comparative analysis, on the operation lines, in assured regime designed for the period 1984-2010 (current state) and future state (A, B, C and D cases), was performed. The energy production requires higher water quantities, in all four cases. In addition, the paper will estimate the climate change impact on hydropower production. The amount of energy produced by hydropower station Mariselu was calculated in

  15. Effects of flow regime on stream turbidity and suspended solids after wildfire, Colorado Front Range

    USGS Publications Warehouse

    Murphy, Sheila F.; McCleskey, R. Blaine; Writer, Jeffrey H.

    2012-01-01

    Wildfires occur frequently in the Colorado Front Range and can alter the hydrological response of watersheds, yet little information exists on the impact of flow regime and storm events on post-wildfire water quality. The flow regime in the region is characterized by base-flow conditions during much of the year and increased runoff during spring snowmelt and summer convective storms. The impact of snowmelt and storm events on stream discharge and water quality was evaluated for about a year after a wildfire near Boulder, Colorado, USA. During spring snowmelt and low-intensity storms, differences in discharge and turbidity at sites upstream and downstream from the burned areas were minimal. However, high-intensity convective storms resulted in dramatic increases in discharge and turbidity at sites downstream from the burned area. This study highlights the importance of using high-frequency sampling to assess accurately wildfire impacts on water quality downstream.

  16. Equatorial atmospheric weather regimes: Their structure and role

    SciTech Connect

    Connors, V.S.

    1991-01-01

    Infrared radiance measurements by the Geostationary Operational Environmental Satellite (GOES-6) from April 1986 through April 1987 are used to characterize and identify distinct regimes of persistent, large-scale cloudiness patterns over the Amazon Basin. These tropical weather regimes are responsible for the continental-scale atmospheric processes that transport air, trace gases, and heat from the Amazon Basin. The cloud patterns are represented by both scene-scale parameters, such as the cloud-free area and the value of the 'clear sky peak' in a histogram, and textural measures, such as contrast of cloudy area and homogeneity or cloudy area. Correlation analyses of the attribute arrays determined that only 9 of the original 15 cloud pattern descriptors are required for the cluster analyses. Seventy-six percent of the satellite images are classified into 1 of 14 weather regimes which persist for periods that range from 3 to 15 days each. The dominant weather regimes are described by the recurrence and duration of the events, by the rainfall produced and energy released to the tropical atmosphere, and by the composite kinematic and thermodynamic analyses. While the classification analyses identified a range of organized weather conditions in the Amazon Basin, two weather regimes, each occurring in separate seasons, dominate the year. The prominent dry season regime (A) occurs 11 times, persists for 25 percent of the year, produces 81 percent of the dry season rainfall, and 7 percent of the energy export necessary to balance the global heat budget. The prominent wet season regime (B) occurs 8 times, persists for 18 percent of the year, delivers about 30 percent of the wet season rainfall, and 16 percent of the energy export requirement. Because the dry season regime (A) draws nearly half of its water vapor supply from local sources, a vital link may exist between the rainforest ecosystem and the dry season rainfall.

  17. The Effects of Rainfall Regimes and Land Use Changes on Runoff and Soil Loss in a Small Mountainous Watershed

    NASA Astrophysics Data System (ADS)

    Fang, N. F.; Shi, Z. H.

    2014-12-01

    This paper analyzes runoff and soil loss in relation to the rainfall regimes and land use changes in a small mountainous watershed in the Three Gorges Area (TGA) of China. Based on 10 years of rainfall measurements and K-means clustering, 152 rainfall events were classified into three rainfall regimes. The mean statistical features of different rainfall regimes display a marked difference. Rainfall Regime I is events of medium amounts (31.8 mm) and medium duration (1371 min). Rainfall Regime II is events with high amounts (54.0 mm), long duration (2548 min), and an infrequent occurrence. Rainfall Regime III is events of low amount (22.2 mm), short duration (494 min) and high frequency. Each rainfall regime results in differing levels of runoff and erosion and Rainfall Regime I causes the greatest proportion of accumulated discharge (368.7 mm) and soil loss (4283 t). In the different rainfall regimes, the values of the mean runoff coefficient and the mean sediment load were ordered as follows: Rainfall Regime II > Rainfall Regime I > Rainfall Regime III. These results suggest that greater attention should be paid to Rainfall Regimes I and II because they had the most erosive effect. In the Wangjiaqiao watershed, the changes in land use primarily affected the paddy fields, where the cropland decreased significantly and the forest and orchards increased by 9.9% and 7.7%, respectively, during 1995-2004. The ANOVA shows land use changes caused significant decreasing trends in the runoff coefficients (P<0.01) and sediment loads (P<0.01). In order, the most sensitive response of runoff and erosion to land use was Rainfall Regime II > Rainfall Regime > Rainfall Regime III. Rainfall characteristics are decisive for the relative importance of different storm runoff generation mechanisms. The land use changes in the study watershed have considerably decreased runoff and soil loss.

  18. Demonstration of high performance negative central magnetic shear discharges on the DIII-D tokamak

    SciTech Connect

    Rice, B.W.; Burrell, K.H.; Lao, L.L.

    1996-01-01

    Reliable operation of discharges with negative central magnetic shear has led to significant increases in plasma performance and reactivity in both low confinement, L-mode, and high confinement, H-mode, regimes in the DIII-D tokamak. Using neutral beam injection early in the initial current ramp, a large range of negative shear discharges have been produced with durations lasting up to 3.2 s. The total non- inductive current (beam plus bootstrap) ranges from 50% to 80% in these discharges. In the region of shear reversal, significant peaking of the toroidal rotation [f{sub {phi}} {approx} 30-60 kHz] and ion temperature [T{sub i}(0) {approx} 15-22 keV] profiles are observed. In high power discharges with an L-mode edge, peaked density profiles are also observed. Confinement enhancement factors up to H {equivalent_to} {tau}{sub E}/{tau}{sub ITER-89P} {approx} 2.5 with an L-mode edge, and H {approx} 3.3 in an Edge Localized Mode (ELM)-free H-mode, are obtained. Transport analysis shows both ion thermal diffusivity and particle diffusivity to be near or below standard neoclassical values in the core. Large pressure peaking in L- mode leads to high disruptivity with {Beta}{sub N} {equivalent_to} {Beta}{sub T}/(I/aB) {<=} 2.3, while broader pressure profiles in H- mode gives low disruptivity with {Beta}{sub N} {<=} 4.2.

  19. Development of dielectric barrier discharging power supply

    NASA Astrophysics Data System (ADS)

    Gao, Yinghui; Liu, Kun; Fu, Rongyao; Sun, Yaohong; Yan, Ping

    2015-11-01

    Due to the demand of a dielectric barrier discharge power supply, a high voltage and high frequency AC power supply was designed and implemented. Its output voltage is standard or approximate standard sine waveform with the frequency range of 1 kHz to 50 kHz. The output voltage and output frequency can be adjusted individually. The maximum output power of the power supply is 2 kW. It can be operated through local or remote control. The power supply has been used in the dielectric barrier discharging research under different conditions.

  20. High-repetition-rate short-pulse gas discharge.

    PubMed

    Tulip, J; Seguin, H; Mace, P N

    1979-09-01

    A high-average-power short-pulse gas discharge is described. This consists of a volume-preionized transverse discharge of the type used in gas lasers driven by a Blumlein energy storage circuit. The Blumlein circuit is fabricated from coaxial cable, is pulse-charged from a high-repetition-rate Marx-bank generator, and is switched by a high-repetition-rate segmented rail gap. The operation of this discharge under conditions typical of rare-gas halide lasers is described. A maximum of 900 pps was obtained, giving a power flow into the discharge of 30 kW. PMID:18699678

  1. Degradation of Verapamil hydrochloride in water by gliding arc discharge.

    PubMed

    Krishna, Syam; Maslani, Alan; Izdebski, Tomasz; Horakova, Marta; Klementova, Sarka; Spatenka, Petr

    2016-06-01

    This study investigated the influence of gliding arc plasma discharge on the degradation of Verapamil hydrochloride in water. The plasma discharge was characterized by means of optical emission spectroscopy. Spectra of various atomic and molecular species were observed. Aqueous solution of Verapamil hydrochloride was exposed to gliding arc discharge operated in continuous discharge at atmospheric pressure and room temperature. The identification of Verapamil, the degradation mechanisms of Verapamil and its transformation products were performed using liquid chromatography - mass spectrometry (HPLC-MS). Experimental results indicate that the atmospheric pressure gliding arc plasma treatment has noticeable effects on Verapamil with satisfactory degradation efficiency. Plausible mechanisms of the degradation were discussed. PMID:26953731

  2. Brain aneurysm repair - discharge

    MedlinePlus

    ... apply pressure An arm or leg that changes color, becomes cool to touch, or becomes numb Redness, pain, or yellow or green discharge in or around the incision site A fever higher than 101°F (38.3°C) or chills

  3. Longitudinal discharge laser baffles

    DOEpatents

    Warner, B.E.; Ault, E.R.

    1994-06-07

    The IR baffles placed between the window and the electrode of a longitudinal discharge laser improve laser performance by intercepting off-axis IR radiation from the laser and in doing so reduce window heating and subsequent optical distortion of the laser beam. 1 fig.

  4. Longitudinal discharge laser baffles

    DOEpatents

    Warner, Bruce E.; Ault, Earl R.

    1994-01-01

    The IR baffles placed between the window and the electrode of a longitudinal discharge laser improve laser performance by intercepting off-axis IR radiation from the laser and in doing so reduce window heating and subsequent optical distortion of the laser beam.

  5. Discharging older patients.

    PubMed

    2016-09-01

    Significant numbers of older people with dementia use general hospital services, and ensuring the safe and appropriate discharge home of patients with poor cognition, impaired judgement, misperception or reduced risk awareness is complex and challenging for many healthcare professionals. PMID:27615354

  6. Electrical Discharge Machining.

    ERIC Educational Resources Information Center

    Montgomery, C. M.

    The manual is for use by students learning electrical discharge machining (EDM). It consists of eight units divided into several lessons, each designed to meet one of the stated objectives for the unit. The units deal with: introduction to and advantages of EDM, the EDM process, basic components of EDM, reaction between forming tool and workpiece,…

  7. A dc glow discharge as a source of electrons for a portable mass spectrometer: characterization of the electron current intensity and electron kinetic energy distribution

    NASA Astrophysics Data System (ADS)

    Chalkha, A.; Despenes, C.; Janulyte, A.; Zerega, Y.; Andre, J.; Brkic, B.; Taylor, S.

    2015-02-01

    A dc glow discharge cell with planar electrodes operating at about 1 Torr has been characterized with an inlet flow from ambient air. It will be used as a source of electrons to further ionize molecules by electron impact in a portable mass spectrometer. The Paschen curve has been measured for six values of the pressure around the minimum of the curve. The voltage-current characteristic, observed until 7 mA for different values of the pressure, increases with current in the normal glow regime. The temporal evolution of the discharge current has been recorded over long periods greater than one day for different insulator materials. The best stability has been obtained with Macor and Nylon. The available electron current for ionization has been measured at about 0.6 µA and the electron kinetic energy distribution has been found to be between 0 and a few tens of eV.

  8. Effects of hydrologic infrastructure on flow regimes of California's Central Valley rivers: Implications for fish populations

    USGS Publications Warehouse

    Brown, Larry R.; Bauer, Marissa L.

    2010-01-01

    Alteration of natural flow regimes is generally acknowledged to have negative effects on native biota; however, methods for defining ecologically appropriate flow regimes in managed river systems are only beginning to be developed. Understanding how past and present water management has affected rivers is an important part of developing such tools. In this paper, we evaluate how existing hydrologic infrastructure and management affect streamflow characteristics of rivers in the Central Valley, California and discuss those characteristics in the context of habitat requirements of native and alien fishes. We evaluated the effects of water management by comparing observed discharges with estimated discharges assuming no water management ("full natural runoff"). Rivers in the Sacramento River drainage were characterized by reduced winter–spring discharges and augmented discharges in other months. Rivers in the San Joaquin River drainage were characterized by reduced discharges in all months but particularly in winter and spring. Two largely unaltered streams had hydrographs similar to those based on full natural runoff of the regulated rivers. The reduced discharges in the San Joaquin River drainage streams are favourable for spawning of many alien species, which is consistent with observed patterns of fish distribution and abundance in the Central Valley. However, other factors, such as water temperature, are also important to the relative success of native and alien resident fishes. As water management changes in response to climate change and societal demands, interdisciplinary programs of research and monitoring will be essential for anticipating effects on fishes and to avoid unanticipated ecological outcomes.

  9. The transition mechanism from a symmetric single period discharge to a period-doubling discharge in atmospheric helium dielectric-barrier discharge

    SciTech Connect

    Zhang, Dingzong; Wang, Yanhui; Wang, Dezhen

    2013-06-15

    Period-doubling and chaos phenomenon have been frequently observed in atmospheric-pressure dielectric-barrier discharges. However, how a normal single period discharge bifurcates into period-doubling state is still unclear. In this paper, by changing the driving frequency, we study numerically the transition mechanisms from a normal single period discharge to a period-doubling state using a one-dimensional self-consistent fluid model. The results show that before a discharge bifurcates into a period-doubling state, it first deviates from its normal operation and transforms into an asymmetric single period discharge mode. Then the weaker discharge in this asymmetric discharge will be enhanced gradually with increasing of the frequency until it makes the subsequent discharge weaken and results in the discharge entering a period-doubling state. In the whole transition process, the spatial distribution of the charged particle density and the electric field plays a definitive role. The conclusions are further confirmed by changing the gap width and the amplitude of the applied voltage.

  10. Defining a Superlens Operating Regime for Imaging Fluorescent Molecules

    PubMed Central

    Elsayad, Kareem; Heinze, Katrin G.

    2009-01-01

    It has been shown that thin metal-based films can at certain frequencies act as planar near-field lenses for certain polarization components. A desirable property of such “lenses” is that they can also enhance and focus some large transverse spatial frequency components which contain sub-diffraction limit details. Over the last decade there has been much work in optimizing designs to reduce effects (such as material losses and surface roughness) that are detrimental to image reconstruction. One design that can reduce some of these undesirable effects, and which has received a fair amount of attention recently, is the stacked metal-dielectric superlens. Here we theoretically explore the imaging ability of such a design for the specific purpose of imaging a fluorescent dye (the common bio-marker GFP) in the vicinity of the superlens surface. Our calculations take into consideration the interaction (damping) of an oscillating electric dipole with the metallic layers in the superlens. We also assume a Gaussian frequency distribution spectrum for the dipole. We treat the metallic-alloy and dielectric-alloy layers separately using an appropriate effective medium theory. The transmission properties are evaluated via Transfer matrix (-matrix) calculations that were performed in the MatLab and MathCad environments. Our study shows that it is in principle possible to image fluorescent molecules using a simple bilayer planar superlens. We find that optimal parameters for such a superlens occur when the peak dipole emission-frequency is slightly offset from the Surface Plasmon resonance frequency of the metal-dielectric interfaces. The best resolution is obtained when the fluorescent molecules are not too close ( nm) or too far ( nm) from the superlens surface. The realization and application of a superlens with the specified design is possible using current nanofabrication techniques. When combined with e.g. a sub-wavelength grating structure (such as in the far-field superlens design previously proposed [1]) or a fast near-field scanning probe, it could provide a means for fast fluorescent imaging with sub-diffraction limit resolution. PMID:19956608

  11. 46 CFR 154.1838 - Discharge by gas pressurization.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Operations § 154.1838 Discharge... pressurizing medium is the cargo vapor or a nonflammable, nontoxic gas that is inert with the cargo; and...

  12. Zero discharge programs require careful planning

    SciTech Connect

    Buecker, B.

    1997-05-01

    Environmental regulations, increasing scarcity of fresh water supplies and rising costs of clean water production have contributed to greater water conservation throughout the country. Reduced or zero discharge programs have become much more commonplace at electric utilities, chemical process industries and manufacturing facilities. Water conservation can be a very complicated issue, with methods varying considerably from site to site. The issues that influence water reduction programs include: quality, quantity and cost of fresh water available to the plant; quality of water needed for various plant processes; ability to recycle wastewater streams to other plant processes; techniques for water treatment; capital, operations, maintenance and labor costs, and floor space and construction requirements for water treatment equipment, pilot testing of proposed treatment methods and environmental restrictions on the quantity and quality of any wastewater that may be discharged. This article describes several water discharge programs available to address the complex needs of each unique plant site.

  13. Breddin's graph for tectonic regimes

    NASA Astrophysics Data System (ADS)

    Célérier, Bernard; Séranne, Michel

    2001-05-01

    A simple graphical method is proposed to infer the tectonic regime from a fault and slip data set. An abacus is overlaid on a plot of the rake versus strike of the data. This yields the horizontal principal stress directions and a constraint on the stress tensor aspect ratio, in a manner similar to Breddin's graph for two-dimensional strain analysis. The main requirement is that one of the principal stress directions is close to the vertical. This method is illustrated on monophase synthetic and natural data, but is also expected to help sort out multiphase data sets.

  14. A comparison of polypropylene-surface treatment by filamentary, homogeneous and glow discharges in helium at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Massines, F.; Gouda, G.

    1998-12-01

    Three different dielectric barrier-controlled discharge regimes in helium at atmospheric pressure under sinusoidal excitation have been obtained by varying the excitation frequency or the gas chemical composition: the filamentary discharge, which is the discharge that is usually obtained; the glow discharge, which is controlled by cathode secondary emission; and the homogeneous discharge, which is of a nature in between those of the filamentary and the glow discharges. All the characteristics that have been studied, such as the discharge current, the emission spectrum, the wettability and the chemical transformations of a polypropylene film, are related to the discharge-regime variation. The glow discharge is clearly more efficient than the others as a means of increasing the polypropylene-surface energy. Values as high as 62 mJ 0022-3727/31/24/003/img1 are obtained with this discharge whereas the maximum value after interaction with the filamentary one is 45 mJ 0022-3727/31/24/003/img1. This improvement in wettability is due to there being more O atoms implanted at the surface as well as to the addition of N atoms. The differences among in surface transformations have been correlated to the characteristics of these different discharges and more specifically to the localization of the electrical energy transfer into the gas and to the nature of the ions created during the discharge.

  15. Electric-discharge-pumped nitrogen ion laser

    NASA Technical Reports Server (NTRS)

    Laudenslager, J. B.; Pacala, T. J.; Wittig, C.

    1976-01-01

    The routine operation is described of an N2(+) laser oscillating on the first negative band system of N2(+) which is produced in a preionized transverse discharge device. The discharge design incorporates features which favor the efficient production of the excitation transfer reaction of He2(+) with N2. A capacitive discharge switched by means of a high-current grounded grid thyratron is used to meet the design requirement of a volumetric discharge in high-pressure gas mixtures where the electric discharge need not have an ultrafast rise time (greater than 10 nsec) but should be capable of transferring large quantities of stored electric energy to the gas. A peak power of 180 kW in an 8-nsec laser pulse was obtained with a 0.1% mixture of N2 in helium at a total pressure of 3 atm. The most intense laser oscillations were observed on the (0,1) vibrational transition at 427.8 microns.

  16. Magnetic dipole discharges. I. Basic properties

    SciTech Connect

    Stenzel, R. L.; Urrutia, J. M.; Teodorescu-Soare, C. T.; Ionita, C.; Schrittwieser, R.

    2013-08-15

    A simple discharge is described which uses a permanent magnet as a cold cathode and the metallic chamber wall as an anode. The magnet's equator is biased strongly negative, which produces secondary electrons due to the impact of energetic ions. The emitted electrons are highly confined by the strong dipolar magnetic field and the negative potential in the equatorial plane of the magnet. The emitted electrons ionize near the sheath and produce further electrons, which drift across field lines to the anode while the nearly unmagnetized ions are accelerated back to the magnet. A steady state discharge is maintained at neutral pressures above 10{sup −3} mbar. This is the principle of magnetron discharges, which commonly use cylindrical and planar cathodes rather than magnetic dipoles as cathodes. The discharge properties have been investigated in steady state and pulsed mode. Different magnets and geometries have been employed. The role of a background plasma has been investigated. Various types of instabilities have been observed such as sheath oscillations, current-driven turbulence, relaxation instabilities due to ionization, and high frequency oscillations created by sputtering impulses, which are described in more detail in companion papers. The discharge has also been operated in reactive gases and shown to be useful for sputtering applications.

  17. A surfactant film spreading regime

    SciTech Connect

    Nikishov, V.I.

    1984-06-01

    Interest has recently increased in the study of the mechanisms whereby oil spills spread over sea and ocean surfaces. In the later stages of this process, when the petroleum film thickness becomes sufficiently small, the main forces determining the growth of its horizontal dimensions are surface tension and viscosity. In this case the flow characteristics do not depend on total quantity of spreading substance nor its surface concentration distribution. However, in the final stages of the spreading process the film becomes so thin that it is necessary to consider the effect of surface concentration distribution of the material on the process. Similar problems occur in the study of the spreading of a surfactant in the case where the total quantity of material is small and the surface tension regime sets in quickly. Therefore, the author examines here the spreading of a film in a regime wherein it is necessary to consider the total quantity of surfactant present, initially located on the surface of a viscous incompressible liquid.

  18. Adaptation in Collaborative Governance Regimes

    NASA Astrophysics Data System (ADS)

    Emerson, Kirk; Gerlak, Andrea K.

    2014-10-01

    Adaptation and the adaptive capacity of human and environmental systems have been of central concern to natural and social science scholars, many of whom characterize and promote the need for collaborative cross-boundary systems that are seen as flexible and adaptive by definition. Researchers who study collaborative governance systems in the public administration, planning and policy literature have paid less attention to adaptive capacity specifically and institutional adaptation in general. This paper bridges the two literatures and finds four common dimensions of capacity, including structural arrangements, leadership, knowledge and learning, and resources. In this paper, we focus on institutional adaptation in the context of collaborative governance regimes and try to clarify and distinguish collaborative capacity from adaptive capacity and their contributions to adaptive action. We posit further that collaborative capacities generate associated adaptive capacities thereby enabling institutional adaptation within collaborative governance regimes. We develop these distinctions and linkages between collaborative and adaptive capacities with the help of an illustrative case study in watershed management within the National Estuary Program.

  19. Adaptation in collaborative governance regimes.

    PubMed

    Emerson, Kirk; Gerlak, Andrea K

    2014-10-01

    Adaptation and the adaptive capacity of human and environmental systems have been of central concern to natural and social science scholars, many of whom characterize and promote the need for collaborative cross-boundary systems that are seen as flexible and adaptive by definition. Researchers who study collaborative governance systems in the public administration, planning and policy literature have paid less attention to adaptive capacity specifically and institutional adaptation in general. This paper bridges the two literatures and finds four common dimensions of capacity, including structural arrangements, leadership, knowledge and learning, and resources. In this paper, we focus on institutional adaptation in the context of collaborative governance regimes and try to clarify and distinguish collaborative capacity from adaptive capacity and their contributions to adaptive action. We posit further that collaborative capacities generate associated adaptive capacities thereby enabling institutional adaptation within collaborative governance regimes. We develop these distinctions and linkages between collaborative and adaptive capacities with the help of an illustrative case study in watershed management within the National Estuary Program. PMID:25073764

  20. Different regimes of dynamic wetting

    NASA Astrophysics Data System (ADS)

    Gustav, Amberg; Wang, Jiayu; Do-Quang, Minh; Shiomi, Junichiro; Physiochemical fluid mechanics Team; Maruyama-Chiashi Laboratory Team

    2014-11-01

    Dynamic wetting, as observed when a droplet contacts a dry solid surface, is important in various engineering processes, such as printing, coating, and lubrication. Our overall aim is to investigate if and how the detailed properties of the solid surface influence the dynamics of wetting. Here we discuss how surface roughness influences the initial dynamic spreading of a partially wetting droplet by studying the spreading on a solid substrate patterned with microstructures just a few micrometers in size. This is complemented by matching numerical simulations. We present a parameter map, based on the properties of the liquid and the solid surface, which identifies qualitatively different spreading regimes, where the spreading speed is limited by either the liquid viscosity, the surface properties, or the liquid inertia. The peculiarities of the different spreading regimes are studied by detailed numerical simulations, in conjuction with experiments. This work was financially supported in part by, the Japan Society for the Promotion of Science (J.W. and J.S) and Swedish Governmental Agency for Innovation Systems (M.D.-Q. and G.A).

  1. Discharge pulse phenomenology

    NASA Technical Reports Server (NTRS)

    Frederickson, A. R.

    1985-01-01

    A model was developed which places radiation induced discharge pulse results into a unified conceptual framework. Only two phenomena are required to interpret all space and laboratory results: (1) radiation produces large electrostatic fields inside insulators via the trapping of a net space charge density; and (2) the electrostatic fields initiate discharge streamer plasmas similar to those investigated in high voltage electrical insulation materials; these streamer plasmas generate the pulsing phenomena. The apparent variability and diversity of results seen is an inherent feature of the plasma streamer mechanism acting in the electric fields which is created by irradiation of the dielectrics. The implications of the model are extensive and lead to constraints over what can be done about spacecraft pulsing.

  2. Effects of discharge chamber length on the negative ion generation in volume-produced negative hydrogen ion source

    SciTech Connect

    Chung, Kyoung-Jae; Jung, Bong-Ki; An, YoungHwa; Dang, Jeong-Jeung; Hwang, Y. S.

    2014-02-15

    In a volume-produced negative hydrogen ion source, control of electron temperature is essential due to its close correlation with the generation of highly vibrationally excited hydrogen molecules in the heating region as well as the generation of negative hydrogen ions by dissociative attachment in the extraction region. In this study, geometric effects of the cylindrical discharge chamber on negative ion generation via electron temperature changes are investigated in two discharge chambers with different lengths of 7.5 cm and 11 cm. Measurements with a radio-frequency-compensated Langmuir probe show that the electron temperature in the heating region is significantly increased by reducing the length of the discharge chamber due to the reduced effective plasma size. A particle balance model which is modified to consider the effects of discharge chamber configuration on the plasma parameters explains the variation of the electron temperature with the chamber geometry and gas pressure quite well. Accordingly, H{sup −} ion density measurement with laser photo-detachment in the short chamber shows a few times increase compared to the longer one at the same heating power depending on gas pressure. However, the increase drops significantly as operating gas pressure decreases, indicating increased electron temperatures in the extraction region degrade dissociative attachment significantly especially in the low pressure regime. It is concluded that the increase of electron temperature by adjusting the discharge chamber geometry is efficient to increase H{sup −} ion production as long as low electron temperatures are maintained in the extraction region in volume-produced negative hydrogen ion sources.

  3. Effects of discharge chamber length on the negative ion generation in volume-produced negative hydrogen ion source.

    PubMed

    Chung, Kyoung-Jae; Jung, Bong-Ki; An, YoungHwa; Dang, Jeong-Jeung; Hwang, Y S

    2014-02-01

    In a volume-produced negative hydrogen ion source, control of electron temperature is essential due to its close correlation with the generation of highly vibrationally excited hydrogen molecules in the heating region as well as the generation of negative hydrogen ions by dissociative attachment in the extraction region. In this study, geometric effects of the cylindrical discharge chamber on negative ion generation via electron temperature changes are investigated in two discharge chambers with different lengths of 7.5 cm and 11 cm. Measurements with a radio-frequency-compensated Langmuir probe show that the electron temperature in the heating region is significantly increased by reducing the length of the discharge chamber due to the reduced effective plasma size. A particle balance model which is modified to consider the effects of discharge chamber configuration on the plasma parameters explains the variation of the electron temperature with the chamber geometry and gas pressure quite well. Accordingly, H(-) ion density measurement with laser photo-detachment in the short chamber shows a few times increase compared to the longer one at the same heating power depending on gas pressure. However, the increase drops significantly as operating gas pressure decreases, indicating increased electron temperatures in the extraction region degrade dissociative attachment significantly especially in the low pressure regime. It is concluded that the increase of electron temperature by adjusting the discharge chamber geometry is efficient to increase H(-) ion production as long as low electron temperatures are maintained in the extraction region in volume-produced negative hydrogen ion sources. PMID:24593559

  4. Nonlinear-optical frequency-doubling metareflector: pulsed regime

    NASA Astrophysics Data System (ADS)

    Popov, A. K.; Myslivets, S. A.

    2016-01-01

    The properties of backward-wave second-harmonic metareflector operating in pulse regime are investigated. It is made of metamaterial which enables phase matching of contra-propagating fundamental and second-harmonic waves. References are given to the works that prove such a possibility. Physical principles underlying differences in the proposed and standard settings as well as between continuous-wave and pulsed regimes are discussed. Pulsed regime is more practicable and has a broader scope of applications. A set of partial differential equations which describe such a reflector with the account for losses are solved numerically. It is shown that unlike second-harmonic generation in standard settings, contra-propagating pulse of second harmonic may become much longer than the incident fundamental one and the difference grows with decrease in the input pulse length as compared to thickness of the metaslab. The revealed properties are important for applications and may manifest themselves beyond the optical wavelength range.

  5. Can global hydrological models reproduce large scale river flood regimes?

    NASA Astrophysics Data System (ADS)

    Eisner, Stephanie; Flörke, Martina

    2013-04-01

    River flooding remains one of the most severe natural hazards. On the one hand, major flood events pose a serious threat to human well-being, causing deaths and considerable economic damage. On the other hand, the periodic occurrence of flood pulses is crucial to maintain the functioning of riverine floodplains and wetlands, and to preserve the ecosystem services the latter provide. In many regions, river floods reveal a distinct seasonality, i.e. they occur at a particular time during the year. This seasonality is related to regionally dominant flood generating processes which can be expressed in river flood types. While in data-rich regions (esp. Europe and North America) the analysis of flood regimes can be based on observed river discharge time series, this data is sparse or lacking in many other regions of the world. This gap of knowledge can be filled by global modeling approaches. However, to date most global modeling studies have focused on mean annual or monthly water availability and their change over time while simulating discharge extremes, both floods and droughts, still remains a challenge for large scale hydrological models. This study will explore the ability of the global hydrological model WaterGAP3 to simulate the large scale patterns of river flood regimes, represented by seasonal pattern and the dominant flood type. WaterGAP3 simulates the global terrestrial water balance on a 5 arc minute spatial grid (excluding Greenland and Antarctica) at a daily time step. The model accounts for human interference on river flow, i.e. water abstraction for various purposes, e.g. irrigation, and flow regulation by large dams and reservoirs. Our analysis will provide insight in the general ability of global hydrological models to reproduce river flood regimes and thus will promote the creation of a global map of river flood regimes to provide a spatially inclusive and comprehensive picture. Understanding present-day flood regimes can support both flood risk

  6. Interannual variability of snow and fluvial regimes in Andorra

    NASA Astrophysics Data System (ADS)

    Pesado, Cristina; Riba, Sergi; Pons, Marc; Lopez-Moreno, Juan Ignacio

    2016-04-01

    Highlands in Andorra are snow-dominated areas during all the winter and most of the spring season. Interannual snow variability in these areas has a strong and straight influence on the amount and seasonality of river regimes at the bottom of the valley where most of the population and water requirements are concentrated. The present study analyzes the temporal and spatial variability of the fluvial regimes in Andorra and seeks to understand the interplay of different topographic and climatic variables on this variability. For example, in mountainous regions temperature determines the state of precipitation and this state can significantly affect runoff formation. The interannual temporal and spatial variability of temperatures, pluviometry and different snow indices such as snow heights and days with snow on the ground has been studied for the last decade and correlated with the fluvial dynamics and its variability using discharge measurements. This study focus especially in the assessment of the role of snow and its seasonality in the fluvial regime dynamics and the influence in the torrential flows and flood hazard. Flood hazard, force to take protection measures, which need information about flood frequency and magnitude. For this, flow instrumental series are used, but usually they do not consider phenomena like snowmelt. This study contributes intends to better understand the interplay between snow and fluvial dynamics and improve the assessment of the availability of water resources as well as the requirements in terms of protection measures.

  7. Electrostatic discharge test apparatus

    NASA Technical Reports Server (NTRS)

    Smith, William Conrad (Inventor)

    1988-01-01

    Electrostatic discharge properties of materials are quantitatively measured and ranked. Samples are rotated on a turntable beneath selectable, co-available electrostatic chargers, one being a corona charging element and the other a sample-engaging triboelectric charging element. Samples then pass under a voltage meter to measure the amount of residual charge on the samples. After charging is discontinued, measurements are continued to record the charge decay history over time.

  8. Discharge borders wars

    SciTech Connect

    Sweeney, N.J. )

    1991-05-01

    This article discusses the impact of a downstream state's standards on the application for a National Pollutant Discharge Elimination System (NPDES) permit by a downstream state as recently explained in a federal court of appeals decision. The litigation discussed included the EPA and the states of Oklahoma and Arkansas. Topics covered include a description of the situation that brought about the litigation, the initial ruling by the EPA and the federal court's reasoning for the final outcome.

  9. Electrostatic discharge test apparatus

    NASA Technical Reports Server (NTRS)

    Smith, William C. (Inventor)

    1989-01-01

    Electrostatic discharge properties of materials are quantitatively measured and ranked. Samples (20) are rotated on a turntable (15) beneath selectable, co-available electrostatic chargers (30/40), one being a corona charging element (30) and the other a sample-engaging triboelectric charging element (40). They then pass under a voltage meter (25) to measure the amount of residual charge on the samples (20). After charging is discontinued, measurements are continued to record the charge decay history over time.

  10. Influence of the anode processes on discharges driven by thermionic emission

    SciTech Connect

    Levko, Dmitry

    2015-07-15

    The influence of electron reflection and secondary electron emission due to electron impact from the anode on discharges driven by thermionic emission is studied by the self-consistent one-dimensional particle-in-cell Monte Carlo collisions model. Two regimes are considered. In the first regime, the two-stream instability is excited and large anode sheath potential is obtained. It is found that in this regime, the reflected electrons play a significant role. In the second regime, the instability is not excited and the anode sheath potential is small. The dominant anode process in this regime is the secondary electron emission. It is shown that in both regimes, the anode processes significantly influence the plasma parameters.

  11. Impurity Particle Transport in High Confinement Regimes Without ELMs on DIII-D

    NASA Astrophysics Data System (ADS)

    Grierson, B. A.

    2014-10-01

    Recent experiments on DIII-D using trace levels of fluorine gas injection have shown that high confinement regimes without ELMs can achieve rapid transport of impurity ions. Much attention has recently been given to regimes with H-mode energy confinement without edge-localized modes (ELMs), accessed either through Resonant Magnetic Perturbations (RMPs) or MHD such as edge harmonic oscillations or quasi-coherent edge oscillations. Experiments on DIII-D have used gas puffing of trace levels of fluorine to introduce this fully-stripped, non-intrinsic and non-recycling impurity that can be easily measured with charge-exchange recombination spectroscopy. Trace fluorine is used because the time-history of the fluorine density profile permits direct extraction of the confinement time, particle diffusivity and convective velocity without relying on atomic modeling or assumptions about the source recycling. Results indicate impurity accumulation is more pronounced in RMP ELM suppressed plasmas with a pure n = 3 spectrum compared with mixed n = 1 and n = 3 RMP fields with reduced number of control coils. In cases where strong central carbon impurity accumulation occurs, trace fluorine analysis reveals a strong inward impurity pinch. Conversely, in plasmas with weak central carbon accumulation, the fluorine pinch is significantly lower. These measurements of impurity influx are consistent with TGLF modeling of the ELM-suppressed phase of the discharge revealing that strong impurity influx occurs when the ratio V/D is between -1 to -3. In this work, the dependencies of impurity transport on local driving gradients will be presented, and the means of increasing the impurity diffusion to recover high purity plasmas will be discussed providing a basis for achieving low-dilution, stationary ELM-free operation in ITER and future devices. Supported by the US DOE under DE-AC0-09CH11466 and DE-FC02-05ER54698.

  12. Powerful glow discharge excilamp

    DOEpatents

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

    2002-01-01

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

  13. Modeling electronegative plasma discharge

    SciTech Connect

    Lichtenberg, A.J.; Lieberman, M.A.

    1995-12-31

    Macroscopic analytic models for a three-component electronegative gas discharge are developed. Assuming the negative ions to be in Boltzmann equilibrium, a positive ion ambipolar diffusion equation is derived. The discharge consists of an electronegative core and electropositive edges. The electron density in the core is nearly uniform, allowing a parabolic approximation to the plasma profile to be employed. The resulting equilibrium equations are solved analytically and matched to a constant mobility transport model of an electropositive edge plasma. The solutions are compared to a simulation of a parallel-plane r.f. driven oxygen plasma for p = 50 mTorr and n{sub eo}= 2.4 x 10{sup 15} m{sup -3}. The ratio {alpha}{sub o} of central negative ion density to electron density, and the electron temperature T{sub e}, found in the simulation, are in reasonable agreement with the values calculated from the model. The model is extended to: (1) low pressures, where a variable mobility model is used in the electropositive edge region; and (2) high {alpha}{sub o} in which the edge region disappears. The inclusion of a second positive ion species, which can be very important in describing electronegative discharges used for materials processing, is a possible extension of the model.

  14. Physics of helicon discharges

    SciTech Connect

    Chen, F.F.

    1996-05-01

    Because of their high density, low-pressure discharges ionized by helicon waves are being studied for their possible use in cluster tools for the fabrication of next-generation computer chips. How helicon waves are related to whistler waves and waves in a plasma-filled waveguide is explained, and the mystery of the high ionization efficiency is outlined. Experimental data on the waves and the equilibrium properties of the discharge are shown, and the status of our current understanding of the physical processes therein is summarized. The importance of kinetic effects and of a short-wavelength mode arising at low magnetic fields is evaluated. Applications of helicon discharges to such diverse fields as plasma accelerators, microwave generators, and tokamak physics are illustrated. Low-temperature plasma physics is often considered a discipline so different from high-temperature plasma physics that there is little overlap, but these studies show that the techniques developed in fusion and space plasma physics can be applied to technological plasmas as well. {copyright} {ital 1996 American Institute of Physics.}

  15. Robustness and uncertainties in future hydrological regimes of Swiss catchments

    NASA Astrophysics Data System (ADS)

    Addor, N.; Roessler, O.; Koeplin, N.; Bernhard, L.; Weingartner, R.; Seibert, J.

    2013-12-01

    Projections of discharge under future climate are impaired by uncertainties arising from different sources: the emission scenarios, the climate models and internal climate variability, the post-processing and sampling of the climate projections, and the hydrological models structure and parameterization. This study aims to investigate the contribution of these sources to the final uncertainty of discharge projections. To this end we performed analyses of variance (ANOVA) in six catchments expected to react differently to climate change and representative of the typical Swiss discharge regimes. We used climate projections of the CH2011 dataset obtained from the Center for Climate Systems Modeling (C2SM). This dataset consists of two types of projections, both relying on the delta change technique. The delta coefficients were determined either in a deterministic way by spectral smoothing of 10 GCM-RCM chains or in a probabilistic way by a Bayesian multi-model approach combining 20 runs until 2050, and then 14 runs until 2099. In addition to the climate projections for emission scenario A1B chosen for the ENSEMBLES project, the CH2011 team generated simulations for the scenarios A2 and RCP3PD using pattern scaling. This enabled us to address the influence of the uncertainty in greenhouse gas emissions on discharge projections. We ran hydrological simulations using three conceptual models: HBV, PREVAH and WaSiM. HBV and PREVAH rely on a similar reservoir structure, while WaSiM uses the more process-oriented Richards-equation approach. PREVAH and WaSiM rely on a higher level of spatial discretization than the lumped HBV model. The use of the three different models allowed evaluation of the sensitivity of discharge projections to the hydrological model complexity and structure. Further, we compared two ways to determine PREVAH parameter values: via calibration and via regionalization. Simulations were run for the periods 2020-2049, 2045-2074 and 2070-2099 to assess the

  16. Effects of a diversion hydropower facility on the hydrological regime of the Correntes River, a tributary to the Pantanal floodplain, Brazil

    NASA Astrophysics Data System (ADS)

    Fantin-Cruz, Ibraim; Pedrollo, Olavo; Girard, Pierre; Zeilhofer, Peter; Hamilton, Stephen K.

    2015-12-01

    Facilities that produce hydroelectricity by diversion of part of the river's flow, which are often considered to have lower environmental impact than conventional hydropower dams, are being built in large numbers on river systems throughout the world, yet their cumulative impacts are not well understood. This study evaluated the hydrological effects of operation of a diversion hydropower facility on the Correntes River in Brazil (mean discharge 73 m3 s-1), which is potentially important because of the ecological implications for the floodplains of the Pantanal into which it flows. Many similar dams are built or proposed on rivers feeding the Pantanal. The 210-MW facility known as Ponte de Pedra diverts part of the river flow into a diversion channel in a nearly "run-of-river" design. The natural (reconstructed) and regulated (observed) flow regimes were characterized using Indicators of Hydrologic Alteration (IHA) and Flow Duration Curves (FDC). Seven parameters of IHA were significantly altered by the reservoir formation (magnitude of lowest monthly flow, minimum flows of 1, 3 and 7 days, maximum flow of 90 days and counts of high and low pulses). Among these, Principal Components Analysis identified the maximum flow of 90 days and the count of high flow pulses as integrators of hydrological alterations. The FDC showed that the reservoir also changed the seasonal regime of the flows, with greater changes in the lowest flow season. The reduction of river-floodplain connectivity and loss of associated ecosystem services are the major downstream ecological implications of this altered flow regime. To maintain the seasonal flooding regime while meeting the requirements for hydroelectric production, proposed limits for flow regime alterations are up to ±18% in low flow, ±24% in the rising limb and ±22% in high flow and the falling limb, relative to the natural flow. Operational changes to maintain flows with these limits could easily be implemented because the

  17. Impurity confinement and transport in high confinement regimes without edge localized modes on DIII-D

    SciTech Connect

    Grierson, B. A. Nazikian, R. M.; Solomon, W. M.; Burrell, K. H.; Garofalo, A. M.; Belli, E. A.; Staebler, G. M.; Evans, T. E.; Smith, S. P.; Chrobak, C.; Fenstermacher, M. E.; McKee, G. R.; Orlov, D. M.; Chrystal, C.

    2015-05-15

    Impurity transport in the DIII-D tokamak [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] is investigated in stationary high confinement (H-mode) regimes without edge localized modes (ELMs). In plasmas maintained by resonant magnetic perturbation (RMP), ELM-suppression, and QH-mode, the confinement time of fluorine (Z = 9) is equivalent to that in ELMing discharges with 40 Hz ELMs. For selected discharges with impurity injection, the impurity particle confinement time compared to the energy confinement time is in the range of τ{sub p}/τ{sub e}≈2−3. In QH-mode operation, the impurity confinement time is shown to be smaller for intense, coherent magnetic, and density fluctuations of the edge harmonic oscillation than weaker fluctuations. Transport coefficients are derived from the time evolution of the impurity density profile and compared to neoclassical and turbulent transport models NEO and TGLF. Neoclassical transport of fluorine is found to be small compared to the experimental values. In the ELMing and RMP ELM-suppressed plasma, the impurity transport is affected by the presence of tearing modes. For radii larger than the mode radius, the TGLF diffusion coefficient is smaller than the experimental value by a factor of 2–3, while the convective velocity is within error estimates. Low levels of diffusion are observed for radii smaller than the tearing mode radius. In the QH-mode plasma investigated, the TGLF diffusion coefficient is higher inside of ρ=0.4 and lower outside of 0.4 than the experiment, and the TGLF convective velocity is more negative by a factor of approximately 1.7.

  18. Plasma Discharge Process in a Pulsed Diaphragm Discharge System

    NASA Astrophysics Data System (ADS)

    Duan, Jianjin; Hu, Jue; Zhang, Chao; Wen, Yuanbin; Meng, Yuedong; Zhang, Chengxu

    2014-12-01

    As one of the most important steps in wastewater treatment, limited study on plasma discharge process is a key challenge in the development of plasma applications. In this study, we focus on the plasma discharge process of a pulsed diaphragm discharge system. According to the analysis, the pulsed diaphragm discharge proceeds in seven stages: (1) Joule heating and heat exchange stage; (2) nucleated site formation; (3) plasma generation (initiation of the breakdown stage); (4) avalanche growth and plasma expansion; (5) plasma contraction; (6) termination of the plasma discharge; and (7) heat exchange stage. From this analysis, a critical voltage criterion for breakdown is obtained. We anticipate this finding will provide guidance for a better application of plasma discharges, especially diaphragm plasma discharges.

  19. Characteristics of radiated power for various TFTR (Tokamak Fusion Test Reactor) regimes

    SciTech Connect

    Bush, C.E.; Schivell, J.; McNeill, D.H.; Medley, S.S.; Hendel, H.W.; Hulse, R.A.; Ramsey, A.T.; Stratton, B.C.; Dylla, H.F.; Grek, B.; Johnson, D.W.; Taylor, G.; Ulrickson, M.; Wieland, R.M.

    1988-04-01

    Power loss studies were carried out to determine the impurity radiation and energy transport characteristics of various TFTR operation and confinement regimes including L-Mode, detached plasma, co-only neutral beam injection (energetic ion regime), and the enhanced confinement (''supershot'') regime. Combined bolometric, spectroscopic, and infrared photometry measurements provide a picture of impurity behavior and power accounting in TFTR. The purpose of this paper is to make a survey of the various regimes with the aim of determining the radiated power signatures of each. 10 refs., 6 figs., 1 tab.

  20. Equivalent circuit analysis of rf discharge plasma and its period doubling behavior due to nonlinear capacitance

    SciTech Connect

    Chung, T.H.; Yoon, H.J.; Lee, J.K.

    1995-12-31

    It has been known that a driven nonlinear RLC circuit can exhibit period doubling (PD) and chaos. The nonlinear element in the circuit is a varacter diode whose capacitance varies as a function of the voltage across it. Capacitively coupled RF Discharge system also displayed a similar characteristic of the nonlinear RLC circuit. In this work, we present computational results obtained using spherical many-particle simulation models. The simulation codes is PDS1 (plasma device spherical one-dimensional) which utilize PIC technique plus Monte Carlo method for the charged particle-neutral collisions. Simulation can reinforce experiment by investigating new parameter regimes and physics associated with new regime outside those seen in the laboratory. When an electrical system with nonlinear impedance characteristics operates periodically with frequency f, higher harmonics will be generated by the nonlinearity at frequencies 2f, 3f, 4f, etc, and subharmonics will also be generated at frequencies f/2, 3f/2, 5f/2, etc. Above a certain power level of the driver, the subharmonics which is indicative of a period-doubling(PD) bifurcation becomes dominant. We plot the PD thresholds for varying pd(where p is the neutral gas pressure, and d is the gap distance). Period doubling bifurcations manifest themselves in driven system by an alternation of state variables between different values on successive cycles of the excitation waveforms. This corresponds to the generation of subharmonics(f/2) and odd-multiples of the half-harmonic frequency.