Efficient coupling of starlight into single mode photonics using Adaptive Injection (AI)

NASA Astrophysics Data System (ADS)

Norris, Barnaby; Cvetojevic, Nick; Gross, Simon; Arriola, Alexander; Tuthill, Peter; Lawrence, Jon; Richards, Samuel; Goodwin, Michael; Zheng, Jessica

2016-08-01

Using single-mode fibres in astronomy enables revolutionary techniques including single-mode interferometry and spectroscopy. However, injection of seeing-limited starlight into single mode photonics is extremely difficult. One solution is Adaptive Injection (AI). The telescope pupil is segmented into a number of smaller subapertures each with size r0, such that seeing can be approximated as a single tip / tilt / piston term for each subaperture, and then injected into a separate fibre via a facet of a segmented MEMS deformable mirror. The injection problem is then reduced to a set of individual tip tilt loops, resulting in high overall coupling efficiency.

Modeling the Influence of Injection Modes on the Evolution of Solution Sprays in a Plasma Jet

NASA Astrophysics Data System (ADS)

Shan, Y.; Coyle, T. W.; Mostaghimi, J.

2010-01-01

Solution precursor plasma spraying (SPPS) is a novel technology with great potential for depositing finely structured ceramic coatings with nano- and sub-micrometric features. The solution is injected into the plasma jet either as a liquid stream or gas atomized droplets. Solution droplets or the stream interact with the plasma jet and break up into fine droplets. The solvent vaporizes very fast as the droplets travel downstream. Solid particles are finally formed, and the particle are heated up and accelerated to the substrate to generate the coating. The deposition process and the properties of coatings obtained are extremely sensitive to the process parameters, such as torch operating conditions, injection modes, injection parameters, and substrate temperatures. This article numerically investigates the effect of injection modes, a liquid stream injection and a gas-blast injection, on the size distribution of injected droplets. The particle/droplet size, temperature, and position distributions on the substrate are predicted for different injection modes.

Plasma Rotation During Neutral Beam Injection In MST

NASA Astrophysics Data System (ADS)

Hudson, Ben; Ding, W.; Fiksel, G.; Prager, S.; Yates, T.

2006-10-01

The effect of fast ions from neutral beam injection (20 keV, 30 A, 1.5 ms) on plasma rotation and magnetic tearing modes is studied. We observe that during co-injected NBI (with the injection in the same direction as the plasma and mode rotation) the rotation of the core-resonant n = 5 magnetic mode decreases and in many instances lock to the vessel wall. There is an associated drop in the poloidal component of n = 5 magnetic mode amplitude. The drop in the mode velocity suggests a counter-directed torque, perhaps due to modification of the radial electric field. The rotation slows during the injection phase, then restores itself on the timescale of the fast ion slowing down time (5 ms @ Te = 100 eV). The fluctuation-induced j x b Maxwell stress is measured using MST's FIR diagnostic and presented for comparison. Equilibrium reconstruction suggests a small increase in on-axis J||, consistent with the presence of a localized fast ion population moving in the direction of the plasma current. Mode rotation during NBI counter-injection is also presented.

INTERNATIONAL CONFERENCE ON SEMICONDUCTOR INJECTION LASERS SELCO-87: Influence of spontaneous fluctuations on the emission spectrum of an injection semiconductor laser

NASA Astrophysics Data System (ADS)

Gulyaev, Yurii V.; Suris, Robert A.; Tager, A. A.; Élenkrig, B. B.

1988-11-01

A theoretical investigation is made of fluctuation-induced excitation of side longitudinal modes in the emission spectra of semiconductor lasers, including those with an external mirror. It is shown that nonlinear refraction of light in the active region of a semiconductor laser may result in a noise redistribution of the radiation between longitudinal resonator modes and can be responsible for the multimode nature of the average emission spectrum. An analysis is made of the influence of selectivity of an external mirror on the stability of cw operation, minimum line width, and mode composition of the emission spectra of semiconductor lasers. The conditions for maximum narrowing of the emission spectrum of a semiconductor laser with an external selective mirror are identified.

Tunable mode and line selection by injection in a TEA CO2 laser

NASA Technical Reports Server (NTRS)

Menzies, R. T.; Flamant, P. H.; Kavaya, M. J.; Kuiper, E. N.

1984-01-01

Tunable mode selection by injection in pulsed CO2 lasers is examined, and both analytical and numerical models are used to compute the required injection power for a variety of experimental cases. These are treated in two categories: mode selection at a desired frequency displacement from the center frequency of a transition line in a dispersive cavity and mode (and line) selection at the center frequency of a selected transition line in a nondispersive cavity. The results point out the potential flexibility of pulsed injection in providing wavelength tunable high-energy single-frequency pulses.

Tunable negative-tap photonic microwave filter based on a cladding-mode coupler and an optically injected laser of large detuning.

PubMed

Chan, Sze-Chun; Liu, Qing; Wang, Zhu; Chiang, Kin Seng

2011-06-20

A tunable negative-tap photonic microwave filter using a cladding-mode coupler together with optical injection locking of large wavelength detuning is demonstrated. Continuous and precise tunability of the filter is realized by physically sliding a pair of bare fibers inside the cladding-mode coupler. Signal inversion for the negative tap is achieved by optical injection locking of a single-mode semiconductor laser. To couple light into and out of the cladding-mode coupler, a pair of matching long-period fiber gratings is employed. The large bandwidth of the gratings requires injection locking of an exceptionally large wavelength detuning that has never been demonstrated before. Experimentally, injection locking with wavelength detuning as large as 27 nm was achieved, which corresponded to locking the 36-th side mode. Microwave filtering with a free-spectral range tunable from 88.6 MHz to 1.57 GHz and a notch depth larger than 35 dB was obtained.

Numerical Simulation of Single-anode and Double-anode Magnetron Injection Guns for 127.5 GHz 1 MW Gyrotron

NASA Astrophysics Data System (ADS)

Singh, Udaybir; Kumar, Nitin; Kumar, Anil; Purohit, Laxmi Prasad; Sinha, Ashok Kumar

2011-07-01

This paper presents the design of two types of magnetron injection guns (MIG's) for 1 MW, 127.5 GHz gyrotron. TE24,8 mode has been chosen as the operating mode. In-house developed code MIGSYN has been used to estimate the initial gun parameters. The electron trajectory tracing program EGUN and in-house developed code MIGANS have been used to optimize the single-anode and the double-anode design for 80 kV, 40 A MIG. The parametric analysis of MIG has also been presented. The advantages and the disadvantages of each kind of configuration have been critically examined.

Effect of injection pressure on performance, emission, and combustion characteristics of diesel-acetylene-fuelled single cylinder stationary CI engine.

PubMed

Srivastava, Anmesh Kumar; Soni, Shyam Lal; Sharma, Dilip; Jain, Narayan Lal

2018-03-01

In this paper, the effect of injection pressure on the performance, emission, and combustion characteristics of a diesel-acetylene fuelled single cylinder, four-stroke, direct injection (DI) diesel engine with a rated power of 3.5 kW at a rated speed of 1500 rpm was studied. Experiments were performed in dual-fuel mode at four different injection pressures of 180, 190, 200, and 210 bar with a flow rate of 120 LPH of acetylene and results were compared with that of baseline diesel operation. Experimental results showed that highest brake thermal efficiency of 27.57% was achieved at injection pressure of 200 bar for diesel-acetylene dual-fuel mode which was much higher than 23.32% obtained for baseline diesel. Carbon monoxide, hydrocarbon, and smoke emissions were also measured and found to be lower, while the NO x emissions were higher at 200 bar in dual fuel mode as compared to those in other injection pressures in dual fuel mode and also for baseline diesel mode. Peak cylinder pressure, net heat release rate, and rate of pressure rise were also calculated and were higher at 200 bar injection pressure in dual fuel mode.

All-optical logic gates and wavelength conversion via the injection locking of a Fabry-Perot semiconductor laser

NASA Astrophysics Data System (ADS)

Harvey, E.; Pochet, M.; Schmidt, J.; Locke, T.; Naderi, N.; Usechak, N. G.

2013-03-01

This work investigates the implementation of all-optical logic gates based on optical injection locking (OIL). All-optical inverting, NOR, and NAND gates are experimentally demonstrated using two distributed feedback (DFB) lasers, a multi-mode Fabry-Perot laser diode, and an optical band-pass filter. The DFB lasers are externally modulated to represent logic inputs into the cavity of the multi-mode Fabry-Perot slave laser. The input DFB (master) lasers' wavelengths are aligned with the longitudinal modes of the Fabry-Perot slave laser and their optical power is used to modulate the injection conditions in the Fabry-Perot slave laser. The optical band-pass filter is used to select a Fabry- Perot mode that is either suppressed or transmitted given the logic state of the injecting master laser signals. When the input signal(s) is (are) in the on state, injection locking, and thus the suppression of the non-injected Fabry-Perot modes, is induced, yielding a dynamic system that can be used to implement photonic logic functions. Additionally, all-optical photonic processing is achieved using the cavity-mode shift produced in the injected slave laser under external optical injection. The inverting logic case can also be used as a wavelength converter — a key component in advanced wavelength-division multiplexing networks. As a result of this experimental investigation, a more comprehensive understanding of the locking parameters involved in injecting multiple lasers into a multi-mode cavity and the logic transition time is achieved. The performance of optical logic computations and wavelength conversion has the potential for ultrafast operation, limited primarily by the photon decay rate in the slave laser.

Design and fabrication of label-free biochip using a guided mode resonance filter with nano grating structures by injection molding process.

PubMed

Cho, E; Kim, B; Choi, S; Han, J; Jin, J; Han, J; Lim, J; Heo, Y; Kim, S; Sung, G Y; Kang, S

2011-01-01

This paper introduces technology to fabricate a guided mode resonance filter biochip using injection molding. Of the various nanofabrication processes that exist, injection molding is the most suitable for the mass production of polymer nanostructures. Fabrication of a nanograting pattern for guided mode resonance filters by injection molding requires a durable metal stamp, because of the high injection temperature and pressure. Careful consideration of the optimized process parameters is also required to achieve uniform sub-wavelength gratings with high fidelity. In this study, a metallic nanostructure pattern to be used as the stamp for the injection molding process was fabricated using electron beam lithography, a UV nanoimprinting process, and an electroforming process. A one-dimensional nanograting substrate was replicated by injection molding, during which the process parameters were controlled. To evaluate the geometric quality of the injection molded nanograting patterns, the surface profile of the fabricated nanograting for different processing conditions was analyzed using an atomic force microscope and a scanning electron microscope. Finally, to demonstrate the feasibility of the proposed process for fabricating guided mode resonance filter biochips, a high-refractive-index material was deposited on the polymer nanograting and its guided mode resonance characteristics were analyzed.

Comparison of field-enhanced and pressure-assisted field-enhanced sample injection techniques for the analysis of water-soluble vitamins using CZE.

PubMed

Liu, Qingqing; Liu, Yaling; Guan, Yu; Jia, Li

2009-04-01

A new online concentration method, namely pressure-assisted field-enhanced sample injection (PA-FESI), was developed and compared with FESI for the analysis of water-soluble vitamins by CZE with UV detection. In PA-FESI, negative voltage and positive pressure were simultaneously applied to initialize PA-FESI. PA-FESI uses the hydrodynamic flow generated by the positive pressure to counterbalance the reverse EOF in the capillary column during electrokinetic sample injection, which allowed a longer injection time than usual FESI mode without compromising the separation efficiency. Using the PA-FESI method, the LODs of the vitamins were at ng/mL level based on the S/N of 3 and the RSDs of migration time and peak area for each vitamin (1 microg/mL) were less than 5.1%. The developed method was applied to the analysis of water-soluble vitamins in corns.

Theoretical and experimental analysis of injection seeding a Q-switched alexandrite laser

NASA Technical Reports Server (NTRS)

Prasad, C. R.; Lee, H. S.; Glesne, T. R.; Monosmith, B.; Schwemmer, G. K.

1991-01-01

Injection seeding is a method for achieving linewidths of less than 500 MHz in the output of broadband, tunable, solid state lasers. Dye lasers, CW and pulsed diode lasers, and other solid state lasers have been used as injection seeders. By optimizing the fundamental laser parameters of pump energy, Q-switched pulse build-up time, injection seed power and mode matching, one can achieve significant improvements in the spectral purity of the Q-switched output. These parameters are incorporated into a simple model for analyzing spectral purity and pulse build-up processes in a Q-switched, injection-seeded laser. Experiments to optimize the relevant parameters of an alexandrite laser show good agreement.

Suppression of Alfven Modes on the National Spherical Torus Experiment Upgrade with Outboard Beam Injection [Suppression of Alfven Modes on the NSTX-U with Outboard Beam Injection

DOE PAGES

Fredrickson, E. D.; Belova, E. V.; Battaglia, D. J.; ...

2017-06-29

In this paper we present data from experiments on the National Spherical Torus Experiment Upgrade, where it is shown for the first time that small amounts of high pitch-angle beam ions can strongly suppress the counterpropagating global Alfven eigenmodes (GAE). GAE have been implicated in the redistribution of fast ions and modification of the electron power balance in previous experiments on NSTX. The ability to predict the stability of Alfven modes, and developing methods to control them, is important for fusion reactors like the International Tokamak Experimental Reactor, which are heated by a large population of nonthermal, super-Alfvenic ions consistingmore » of fusion generated alpha's and beam ions injected for current profile control. We present a qualitative interpretation of these observations using an analytic model of the Doppler-shifted ion-cyclotron resonance drive responsible for GAE instability which has an important dependence on k(perpendicular to rho L). A quantitative analysis of this data with the HYM stability code predicts both the frequencies and instability of the GAE prior to, and suppression of the GAE after the injection of high pitch-angle beam ions.« less

Design and performance of a new continuous-flow sample-introduction system for flame infrared-emission spectrometry: Applications in process analysis, flow injection analysis, and ion-exchange high-performance liquid chromatography.

PubMed

Lam, C K; Zhang, Y; Busch, M A; Busch, K W

1993-06-01

A new sample introduction system for the analysis of continuously flowing liquid streams by flame infrared-emission (FIRE) spectrometry has been developed. The system uses a specially designed purge cell to strip dissolved CO(2) from solution into a hydrogen gas stream that serves as the fuel for a hydrogen/air flame. Vibrationally excited CO(2) molecules present in the flame are monitored with a simple infrared filter (4.4 mum) photometer. The new system can be used to introduce analytes as a continuous liquid stream (process analysis mode) or on a discrete basis by sample injection (flow injection analysis mode). The key to the success of the method is the new purge-cell design. The small internal volume of the cell minimizes problems associated with purge-cell clean-out and produces sharp, reproducible signals. Spent analytical solution is continuously drained from the cell, making cell disconnection and cleaning between samples unnecessary. Under the conditions employed in this study, samples could be analyzed at a maximum rate of approximately 60/h. The new sample introduction system was successfully tested in both a process analysis- and a flow injection analysis mode for the determination of total inorganic carbon in Waco tap water. For the first time, flame infrared-emission spectrometry was successfully extended to non-volatile organic compounds by using chemical pretreatment with peroxydisulfate in the presence of silver ion to convert the analytes into dissolved carbon dioxide, prior to purging and detection by the FIRE radiometer. A test of the peroxydisulfate/Ag(+) reaction using six organic acids and five sugars indicated that all 11 compounds were oxidized to nearly the same extent. Finally, the new sample introduction system was used in conjunction with a simple filter FIRE radiometer as a detection system in ion-exchange high-performance liquid chromatography. Ion-exchange chromatograms are shown for two aqueous mixtures, one containing six organic acids and the second containing six mono-, di-, and trisaccharides.

Progress of long pulse operation with high performance plasma in KSTAR

NASA Astrophysics Data System (ADS)

Bae, Young; Kstar Team

2015-11-01

Recent KSTAR experiments showed the sustained H-mode operation up to the pulse duration of 46 s at the plasma current of 600 kA. The long-pulse H-mode operation has been supported by long-pulse capable neutral beam injection (NBI) system with high NB current drive efficiency attributed by highly tangential injections of three beam sources. In next phase, aiming to demonstrate the long pulse stationary high performance plasma operation, we are attempting the long pulse inductive operation at the higher performance (MA plasma current, high normalized beta, and low q95) for the final goal of demonstration of ITER-like baseline scenario in KSTAR with progressive improvement of the plasma shape control and higher neutral beam injection power. This paper presents the progress of long pulse operation and the analysis of energy confinement time and non-inductive current drive in KSTAR.

Experimental study on combustion modes and thrust performance of a staged-combustor of the scramjet with dual-strut

NASA Astrophysics Data System (ADS)

Yang, Qingchun; Chetehouna, Khaled; Gascoin, Nicolas; Bao, Wen

2016-05-01

To enable the scramjet operate in a wider flight Mach number, a staged-combustor with dual-strut is introduced to hold more heat release at low flight Mach conditions. The behavior of mode transition was examined using a direct-connect model scramjet experiment along with pressure measurements. The typical operating modes of the staged-combustor are analyzed. Fuel injection scheme has a significant effect on the combustor operating modes, particularly for the supersonic combustion mode. Thrust performances of the combustor with different combustion modes and fuel distributions are reported in this paper. The first-staged strut injection has a better engine performance in the operation of subsonic combustion mode. On the contrast, the second-staged strut injection has a better engine performance in the operation of supersonic combustion mode.

Enhanced tunability of the composition in silicon oxynitride thin films by the reactive gas pulsing process

NASA Astrophysics Data System (ADS)

Aubry, Eric; Weber, Sylvain; Billard, Alain; Martin, Nicolas

2014-01-01

Silicon oxynitride thin films were sputter deposited by the reactive gas pulsing process. Pure silicon target was sputtered in Ar, N2 and O2 mixture atmosphere. Oxygen gas was periodically and solely introduced using exponential signals. In order to vary the injected O2 quantity in the deposition chamber during one pulse at constant injection time (TON), the tau mounting time τmou of the exponential signals was systematically changed for each deposition. Taking into account the real-time measurements of the discharge voltage and the I(O*)/I(Ar*) emission lines ratio, it is shown that the oscillations of the discharge voltage during the TON and TOFF times (injection of O2 stopped) are attributed to the preferential adsorption of the oxygen compared to that of the nitrogen. The sputtering mode alternates from a fully nitrided mode (TOFF time) to a mixed mode (nitrided and oxidized mode) during the TON time. For the highest injected O2 quantities, the mixed mode tends toward a fully oxidized mode due to an increase of the trapped oxygen on the target. The oxygen (nitrogen) concentration in the SiOxNy films similarly (inversely) varies as the oxygen is trapped. Moreover, measurements of the contamination speed of the Si target surface are connected to different behaviors of the process. At low injected O2 quantities, the nitrided mode predominates over the oxidized one during the TON time. It leads to the formation of Si3N4-yOy-like films. Inversely, the mixed mode takes place for high injected O2 quantities and the oxidized mode prevails against the nitrided one producing SiO2-xNx-like films.

Prognostic health monitoring in switch-mode power supplies with voltage regulation

NASA Technical Reports Server (NTRS)

Hofmeister, James P (Inventor); Judkins, Justin B (Inventor)

2009-01-01

The system includes a current injection device in electrical communication with the switch mode power supply. The current injection device is positioned to alter the initial, non-zero load current when activated. A prognostic control is in communication with the current injection device, controlling activation of the current injection device. A frequency detector is positioned to receive an output signal from the switch mode power supply and is able to count cycles in a sinusoidal wave within the output signal. An output device is in communication with the frequency detector. The output device outputs a result of the counted cycles, which are indicative of damage to an a remaining useful life of the switch mode power supply.

Solute plumes mean velocity in aquifer transport: Impact of injection and detection modes

NASA Astrophysics Data System (ADS)

Dagan, Gedeon

2017-08-01

Flow of mean velocity U takes place in a heterogeneous aquifer of random spatially variable conductivity K. A solute plume is injected instantaneously along a plane normal to U, over a large area relative to the logconductivity integral scale I (ergodic plume). Transport is by advection by the spatially variable Eulerian velocity. The study is focused on the derivation of the mean plume velocity in the four modes set forth by Kreft and Zuber [1978] for one dimensional flow in a homogeneous medium. In the resident injection mode the mass is initially distributed uniformly in space while in the flux mode it is proportional to the local velocity. In the resident detection mode the mean velocity pertains to the plume centroid, whereas in flux detection it is quantified with the aid of the BTC and the corresponding mean arrival time. In agreement with the literature, it is shown that URR and UFF, pertaining to same injection and detection modes, either resident or flux, are equal to U. In contrast, in the mixed modes the solute velocity may differ significantly from U near the injection plane, approaching it at large distances relative to I. These effects are explained qualitatively with the aid of the exact solution for stratified aquifers.

Mixed Mode Fuel Injector And Injection System

DOEpatents

Stewart, Chris Lee; Tian, Ye; Wang, Lifeng; Shafer, Scott F.

2005-12-27

A fuel injector includes a homogenous charge nozzle outlet set and a conventional nozzle outlet set that are controlled respectively by first and second three way needle control valves. Each fuel injector includes first and second concentric needle valve members. One of the needle valve members moves to an open position for a homogenous charge injection event, while the other needle valve member moves to an open position for a conventional injection event. The fuel injector has the ability to operate in a homogenous charge mode with a homogenous charge spray pattern, a conventional mode with a conventional spray pattern or a mixed mode.

Development of mediated BOD biosensor system of flow injection mode for shochu distillery wastewater.

PubMed

Oota, Shinichi; Hatae, Yuta; Amada, Kei; Koya, Hidekazu; Kawakami, Mitsuyasu

2010-09-15

Although microbial biochemical oxygen demand (BOD) sensors utilizing redox mediators have attracted much attention as a rapid BOD measurement method, little attempts have been made to apply the mediated BOD biosensors to the flow injection analysis system. In this work, a mediated BOD sensor system of flow injection mode, constructed by combining an immobilized microbial reactor with an electrochemical flow cell of three electrodes configuration, has been developed to estimate BOD of shochu distillery wastewater (SDW). It was demonstrated consequently that the mediated sensing was realized by employing phosphate buffer containing potassium hexacyanoferrate as the carrier. The output current was found to yield a peak with a sample injection, and to result from reoxidation of reduced mediator at the electrode. By employing the peak area as the sensor response, the effects of flow rate and pH of the carrier on the sensitivity were investigated. The sensor system using a microorganism of high SDW-assimilation capacity showed good performance and proved to be available for estimation of BOD of SDW. Copyright 2010 Elsevier B.V. All rights reserved.

BEAM DIAGNOSTICS USING BPM SIGNALS FROM INJECTED AND STORED BEAMS IN A STORAGE RING

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

Wang, G.M.; Shaftan; T.

2011-03-28

Many modern light sources are operating in top-off injection mode or are being upgraded to top-off injection mode. The storage ring always has the stored beam and injected beam for top-off injection mode. So the BPM data is the mixture of both beam positions and the injected beam position cannot be measured directly. We propose to use dedicated wide band BPM electronics in the NSLS II storage ring to retrieve the injected beam trajectory with the singular value decomposition (SVD) method. The beam position monitor (BPM) has the capability to measure bunch-by-bunch beam position. Similar electronics can be used tomore » measure the bunch-by-bunch beam current which is necessary to get the injection beam position. The measurement precision of current needs to be evaluated since button BPM sum signal has position dependence. The injected beam trajectory can be measured and monitored all the time without dumping the stored beam. We can adjust and optimize the injected beam trajectory to maximize the injection efficiency. We can also measure the storage ring acceptance by mapping the injected beam trajectory.« less

Interband optical pulse injection locking of quantum dot mode-locked semiconductor laser.

PubMed

Kim, Jimyung; Delfyett, Peter J

2008-07-21

We experimentally demonstrate optical clock recovery from quantum dot mode-locked semiconductor lasers by interband optical pulse injection locking. The passively mode-locked slave laser oscillating on the ground state or the first excited state transition is locked through the injection of optical pulses generated via the opposite transition bands, i.e. the first excited state or the ground state transition from the hybridly mode-locked master laser, respectively. When an optical pulse train generated via the first excited state from the master laser is injected to the slave laser oscillating via ground state, the slave laser shows an asymmetric locking bandwidth around the nominal repetition rate of the slave laser. In the reverse injection case of, i.e. the ground state (master laser) to the first excited state (slave laser), the slave laser does not lock even though both lasers oscillate at the same cavity frequency. In this case, the slave laser only locks to higher injection rates as compared to its own nominal repetition rate, and also shows a large locking bandwidth of 6.7 MHz.

[Rapid screening the alkaloids of poppy shell in hot pot condiment, beef noodle soup and seasoning by direct analysis in real time-tandem mass spectrometry].

PubMed

Zhang, Baile; Gao, Lihong; Xie, Yingshuang; Zhou, Wei; Chen, Xiaofeng; Lei, Chunni; Zhang, Huan

2017-07-08

A direct analysis in real time tandem mass spectrometry (DART-MS/MS) method was established for quickly screening five illegally added alkaloids of poppy shell from the hot pot condiment, beef noodle soup and seasoning. The samples were extracted and purified by acetonitrile, and then injected under the conditions of ionization temperature of 300℃, grid electrode voltage of 150 V and sampling rate of 0.8 mm/s using DART in the positive ion mode. The determination was conducted by tandem mass spectrometry in positive ESI mode under multiple reaction monitoring (MRM) mode. The method is simple and rapid, and can meet the requirement of rapid screening and analysis of large quantities of samples.

Anomalous transport in disordered fracture networks: Spatial Markov model for dispersion with variable injection modes

NASA Astrophysics Data System (ADS)

Kang, Peter K.; Dentz, Marco; Le Borgne, Tanguy; Lee, Seunghak; Juanes, Ruben

2017-08-01

We investigate tracer transport on random discrete fracture networks that are characterized by the statistics of the fracture geometry and hydraulic conductivity. While it is well known that tracer transport through fractured media can be anomalous and particle injection modes can have major impact on dispersion, the incorporation of injection modes into effective transport modeling has remained an open issue. The fundamental reason behind this challenge is that-even if the Eulerian fluid velocity is steady-the Lagrangian velocity distribution experienced by tracer particles evolves with time from its initial distribution, which is dictated by the injection mode, to a stationary velocity distribution. We quantify this evolution by a Markov model for particle velocities that are equidistantly sampled along trajectories. This stochastic approach allows for the systematic incorporation of the initial velocity distribution and quantifies the interplay between velocity distribution and spatial and temporal correlation. The proposed spatial Markov model is characterized by the initial velocity distribution, which is determined by the particle injection mode, the stationary Lagrangian velocity distribution, which is derived from the Eulerian velocity distribution, and the spatial velocity correlation length, which is related to the characteristic fracture length. This effective model leads to a time-domain random walk for the evolution of particle positions and velocities, whose joint distribution follows a Boltzmann equation. Finally, we demonstrate that the proposed model can successfully predict anomalous transport through discrete fracture networks with different levels of heterogeneity and arbitrary tracer injection modes.

Effects of Lightning Injection on Power-MOSFETs

NASA Technical Reports Server (NTRS)

Celaya, Jose; Saha, Sankalita; Wysocki, Phil; Ely, Jay; Nguyen, Truong; Szatkowski, George; Koppen, Sandra; Mielnik, John; Vaughan, Roger; Goebel, Kai

2009-01-01

Lightning induced damage is one of the major concerns in aircraft health monitoring. Such short-duration high voltages can cause significant damage to electronic devices. This paper presents a study on the effects of lightning injection on power metal-oxide semiconductor field effect transistors (MOSFETs). This approach consisted of pin-injecting lightning waveforms into the gate, drain and/or source of MOSFET devices while they were in the OFF-state. Analysis of the characteristic curves of the devices showed that for certain injection modes the devices can accumulate considerable damage rendering them inoperable. Early results demonstrate that a power MOSFET, even in its off-state, can incur considerable damage due to lightning pin injection, leading to significant deviation in its behavior and performance, and to possibly early device failures.

Rotation profile flattening and toroidal flow shear reversal due to the coupling of magnetic islands in tokamaks

DOE PAGES

Tobias, B.; Chen, M.; Classen, I. G. J.; ...

2016-04-15

The electromagnetic coupling of helical modes, including those having different toroidal mode numbers, modifies the distribution of toroidal angular momentum in tokamak discharges. This can have deleterious effects on other transport channels as well as on magnetohydrodynamic (MHD) stability and disruptivity. At low levels of externally injected momentum, the coupling of core-localized modes initiates a chain of events, whereby flattening of the core rotation profile inside successive rational surfaces leads to the onset of a large m/n = 2/1 tearing mode and locked-mode disruption. Furthermore, with increased torque from neutral beam injection, neoclassical tearing modes in the core may phase-lockmore » to each other without locking to external fields or structures that are stationary in the laboratory frame. The dynamic processes observed in these cases are in general agreement with theory, and detailed diagnosis allows for momentum transport analysis to be performed, revealing a significant torque density that peaks near the 2/1 rational surface. However, as the coupled rational surfaces are brought closer together by reducing q95, additional momentum transport in excess of that required to attain a phase-locked state is sometimes observed. Rather than maintaining zero differential rotation (as is predicted to be dynamically stable by single-fluid, resistive MHD theory), these discharges develop hollow toroidal plasma fluid rotation profiles with reversed plasma flow shear in the region between the m/n = 3/2 and 2/1 islands. Additional forces expressed in this state are not readily accounted for, and therefore, analysis of these data highlights the impact of mode coupling on torque balance and the challenges associated with predicting the rotation dynamics of a fusion reactor-a key issue for ITER. Published by AIP Publishing.« less

Rotation profile flattening and toroidal flow shear reversal due to the coupling of magnetic islands in tokamaks

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

Tobias, B.; Grierson, B. A.; Okabayashi, M.

2016-05-15

The electromagnetic coupling of helical modes, even those having different toroidal mode numbers, modifies the distribution of toroidal angular momentum in tokamak discharges. This can have deleterious effects on other transport channels as well as on magnetohydrodynamic (MHD) stability and disruptivity. At low levels of externally injected momentum, the coupling of core-localized modes initiates a chain of events, whereby flattening of the core rotation profile inside successive rational surfaces leads to the onset of a large m/n = 2/1 tearing mode and locked-mode disruption. With increased torque from neutral beam injection, neoclassical tearing modes in the core may phase-lock to each othermore » without locking to external fields or structures that are stationary in the laboratory frame. The dynamic processes observed in these cases are in general agreement with theory, and detailed diagnosis allows for momentum transport analysis to be performed, revealing a significant torque density that peaks near the 2/1 rational surface. However, as the coupled rational surfaces are brought closer together by reducing q{sub 95}, additional momentum transport in excess of that required to attain a phase-locked state is sometimes observed. Rather than maintaining zero differential rotation (as is predicted to be dynamically stable by single-fluid, resistive MHD theory), these discharges develop hollow toroidal plasma fluid rotation profiles with reversed plasma flow shear in the region between the m/n = 3/2 and 2/1 islands. The additional forces expressed in this state are not readily accounted for, and therefore, analysis of these data highlights the impact of mode coupling on torque balance and the challenges associated with predicting the rotation dynamics of a fusion reactor—a key issue for ITER.« less

Effects of air injection on a turbocharged Teledyne Continential Motors TSIO-360-C engine

NASA Technical Reports Server (NTRS)

Cosgrove, D. V.; Kempke, E. E.

1979-01-01

A turbocharged fuel injected aircraft engine was operated over a range of test conditions that included that EPA five-mode emissions cycle and fuel air ratio variations for individual modes while injecting air into the exhaust gas. Air injection resulted in a decrease of hydrocarbons and carbon monoxide while exceeding the maximum recommended turbine inlet temperature of 1650 F at the full rich mixture of the engine. Leanout tests indicated that the EPA standards could be met through the combined use of fuel management and air injection.

Observations of ELM stabilization during neutral beam injection in DIII-D

NASA Astrophysics Data System (ADS)

Bortolon, Alessandro; Kramer, Gerrit; Diallo, Ahmed; Knolker, Matthias; Maingi, Rajesh; Nazikian, Raffi; Degrassie, John; Osborne, Thomas

2017-10-01

Edge localized modes (ELMs) are generally interpreted as peeling-ballooning instabilities, driven by the pedestal current and pressure gradient, with other subdominant effects possibly relevant close to marginal stability. We report observations of transient stabilization of type-I ELMs during neutral beam injection (NBI), emerging from a combined dataset of DIII-D ELMy H-mode plasmas with moderate heating obtained through pulsed NBI waveforms. Statistical analysis of ELM onset times indicates that, in the selected dataset, the likelihood of onset of an ELM lowers significantly during NBI modulation pulses, with the stronger correlation found with counter-current NBI. The effect is also found in rf-heated H-modes, where ELMs appear inhibited when isolated diagnostic beam pulses are applied. Coherent average analysis is used to determine how plasma density, temperature, rotation as well as beam ion quantities evolve during a NB modulation cycle, finding relatively small changes ( 3%) of pedestal Te and ne and toroidal and poloidal rotation variations up to 5 km/s. The effect of these changes on pedestal stability will be discussed. Work supported by US DOE under DE-FC02-04ER54698, DE-AC02-09CH11466.

Fault-Sensitivity and Wear-Out Analysis of VLSI Systems.

DTIC Science & Technology

1995-06-01

DESCRIPTION MIXED-MODE HIERARCIAIFAULT DESCRIPTION FAULT SIMULATION TYPE OF FAULT TRANSIENT/STUCK-AT LOCATION/TIME * _AUTOMATIC FAULT INJECTION TRACE...4219-4224, December 1985. [15] J. Sosnowski, "Evaluation of transient hazards in microprocessor controll - ers," Digest, FTCS-16, The Sixteenth

End-of-injection fuel dribble of multi-hole diesel injector: Comprehensive investigation of phenomenon and discussion on control strategy

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

Moon, Seoksu; Huang, Weidi; Li, Zhilong

The needle shutdown of fuel injectors leads to an undesired fuel dribble that forms unburned hydrocarbons and decreases the engine thermal efficiency in modern engines. Understanding of the fuel dribbling process is of great importance to establish its minimization strategy for optimal use of conventional fuels. However, the detailed needle dynamics and in- and near-nozzle flow characteristics governing the fuel dribble process have not been thoroughly understood. In this study, the needle dynamics, in- and near-nozzle flow characteristics and fuel dribble of a mini-sac type three-hole diesel injector were investigated using a highspeed X-ray phase-contrast imaging technique at different injectionmore » pressures. The results showed that an increase in injection pressure increased the flow evacuation velocity at the needle close that induced a more intense fuel cavitation and air ingestion inside the nozzle. The fuel dribbling process showed a high shot-toshot deviation. A statistical analysis of 50-shot results exhibited two breakup modes of fuel dribble determined by the flow evacuation velocity at the needle close and presence of air ingestion. In the first mode, the fast breakup with a short residence time of fuel dribble occurred. Meanwhile, the dripping of undisturbed liquid column with a long residence time of fuel dribble occurred in the second mode. An increase in injection pressure increased the population of the first mode due to more intense air ingestion that primarily caused by an increase in needle closing speed other than an increase in peak injection velocity. Based on the results, the formation mechanism and control strategies of the fuel dribble from modern diesel injectors were discussed.« less

Nanoliter-Scale Oil-Air-Droplet Chip-Based Single Cell Proteomic Analysis.

PubMed

Li, Zi-Yi; Huang, Min; Wang, Xiu-Kun; Zhu, Ying; Li, Jin-Song; Wong, Catherine C L; Fang, Qun

2018-04-17

Single cell proteomic analysis provides crucial information on cellular heterogeneity in biological systems. Herein, we describe a nanoliter-scale oil-air-droplet (OAD) chip for achieving multistep complex sample pretreatment and injection for single cell proteomic analysis in the shotgun mode. By using miniaturized stationary droplet microreaction and manipulation techniques, our system allows all sample pretreatment and injection procedures to be performed in a nanoliter-scale droplet with minimum sample loss and a high sample injection efficiency (>99%), thus substantially increasing the analytical sensitivity for single cell samples. We applied the present system in the proteomic analysis of 100 ± 10, 50 ± 5, 10, and 1 HeLa cell(s), and protein IDs of 1360, 612, 192, and 51 were identified, respectively. The OAD chip-based system was further applied in single mouse oocyte analysis, with 355 protein IDs identified at the single oocyte level, which demonstrated its special advantages of high enrichment of sequence coverage, hydrophobic proteins, and enzymatic digestion efficiency over the traditional in-tube system.

[Reliability theory based on quality risk network analysis for Chinese medicine injection].

PubMed

Li, Zheng; Kang, Li-Yuan; Fan, Xiao-Hui

2014-08-01

A new risk analysis method based upon reliability theory was introduced in this paper for the quality risk management of Chinese medicine injection manufacturing plants. The risk events including both cause and effect ones were derived in the framework as nodes with a Bayesian network analysis approach. It thus transforms the risk analysis results from failure mode and effect analysis (FMEA) into a Bayesian network platform. With its structure and parameters determined, the network can be used to evaluate the system reliability quantitatively with probabilistic analytical appraoches. Using network analysis tools such as GeNie and AgenaRisk, we are able to find the nodes that are most critical to influence the system reliability. The importance of each node to the system can be quantitatively evaluated by calculating the effect of the node on the overall risk, and minimization plan can be determined accordingly to reduce their influences and improve the system reliability. Using the Shengmai injection manufacturing plant of SZYY Ltd as a user case, we analyzed the quality risk with both static FMEA analysis and dynamic Bayesian Network analysis. The potential risk factors for the quality of Shengmai injection manufacturing were identified with the network analysis platform. Quality assurance actions were further defined to reduce the risk and improve the product quality.

Supermode noise suppression with mutual injection locking for coupled optoelectronic oscillator.

PubMed

Dai, Jian; Liu, Anni; Liu, Jingliang; Zhang, Tian; Zhou, Yue; Yin, Feifei; Dai, Yitang; Liu, Yuanan; Xu, Kun

2017-10-30

The coupled optoelectronic oscillator (COEO) is typically used to generate high frequency spectrally pure microwave signal with serious sidemodes noise. We propose and experimentally demonstrate a simple scheme for supermode suppression with mutual injection locking between the COEO (master oscillator with multi-modes oscillation) and the embedded free-running oscillator (slave oscillator with single-mode oscillation). The master and slave oscillators share the same electrical feedback path, which means that the mutually injection-locked COEO brings no additional hardware complexity. Owing to the mode matching and mutually injection locking effect, 9.999 GHz signal has been successfully obtained by the mutually injection-locked COEO with the phase noise about -117 dBc/Hz at 10 kHz offset frequency. Besides, the supermode noise can be significantly suppressed more than 50 dB to below -120 dBc.

An in vivo analysis of facial muscle change treated with botulinum toxin type A using digital image speckle correlation

NASA Astrophysics Data System (ADS)

Xu, Yan; Palmaccio, Samantha Palmaccio; Bui, Duc; Dagum, Alexander; Rafailovich, Miriam

Been famous for clinical use from early 1980s, the neuromuscular blocking agent Botulinum toxin type A (BTX-A), has been used to reduce wrinkles for a long time. Only little research has been done to quantify the change of muscle contraction before and after injection and most research paper depend on subjective evaluation from both patients and surgeons. In our research, Digital Image Speckle Correlation (DISC) was employed to study the mechanical properties of skin, contraction mode of muscles (injected) and reaction of neighbor muscle group (un-injected).At the same time, displacement patterns (vector maps)generated by DISC can predict injection locus for surgeons who normally handle it depending only on visual observation.

Ponderomotive lower hybrid wave growth in electric fields associated with electron beam injection and transverse ion acceleration

NASA Astrophysics Data System (ADS)

Bale, S. D.; Kellogg, P. J.; Erickson, K. N.; Monson, S. J.; Arnoldy, R. L.

During electron beam injection, the Echo 7 rocket experiment observed large bursts of transversely accelerated ions. These ions seem to have been energized in the region of the beam or the payload return current. Electric field waveforms (<= 30 kHz) during gun operation show both low frequency fluctuations and broad band power. An analysis of the waveforms shows nonlinear mode coupling between waves near the ion cyclotron frequency and waves above the lower hybrid frequency.

Simulated fault injection - A methodology to evaluate fault tolerant microprocessor architectures

NASA Technical Reports Server (NTRS)

Choi, Gwan S.; Iyer, Ravishankar K.; Carreno, Victor A.

1990-01-01

A simulation-based fault-injection method for validating fault-tolerant microprocessor architectures is described. The approach uses mixed-mode simulation (electrical/logic analysis), and injects transient errors in run-time to assess the resulting fault impact. As an example, a fault-tolerant architecture which models the digital aspects of a dual-channel real-time jet-engine controller is used. The level of effectiveness of the dual configuration with respect to single and multiple transients is measured. The results indicate 100 percent coverage of single transients. Approximately 12 percent of the multiple transients affect both channels; none result in controller failure since two additional levels of redundancy exist.

All-Optical Logic Gates and Wavelength Conversion Via the Injection-Locking of a Fabry-Perot Semiconductor Laser

DTIC Science & Technology

2013-03-21

be modified to create a non -inverting output as well. The probe beam is initially injected at a slightly higher frequency than the slave mode so...input signal(s) is (are) in the on state, injection locking, and thus the suppression of the non -injected Fabry–Perot modes, is induced, yielding a...laser diode), SLD (slave laser diode), EOM (electro-optic modulator), P (polarizer), OI (optical isolator), G (grating), L (lens), BE ( beam expander

Multidimensional Mixing Behavior of Steam-Water Flow in a Downcomer Annulus During LBLOCA Reflood Phase with a Direct Vessel Injection Mode

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

Kwon, Tae-Soon; Yun, Byong-Jo; Euh, Dong-Jin

Multidimensional thermal-hydraulic behavior in the downcomer annulus of a pressurized water reactor (PWR) vessel with a direct vessel injection mode is presented based on the experimental observation in the MIDAS (multidimensional investigation in downcomer annulus simulation) steam-water test facility. From the steady-state test results to simulate the late reflood phase of a large-break loss-of-coolant accident (LBLOCA), isothermal lines show the multidimensional phenomena of a phasic interaction between steam and water in the downcomer annulus very well. MIDAS is a steam-water separate effect test facility, which is 1/4.93 linearly scaled down to a 1400-MW(electric) PWR type of a nuclear reactor, focusedmore » on understanding multidimensional thermal-hydraulic phenomena in a downcomer annulus with various types of safety injection during the refill or reflood phase of an LBLOCA. The initial and the boundary conditions are scaled from the pretest analysis based on the preliminary calculation using the TRAC code. The superheated steam with a superheating degree of 80 K at a given downcomer pressure of 180 kPa is injected equally through three intact cold legs into the downcomer.« less

Carbon microgranule injection into NSTX-U discharges for edge diagnostic research

NASA Astrophysics Data System (ADS)

Lunsford, Robert; Roquemore, A. Lane; Scotti, Filippo; Mansfield, Dennis; Bortolon, Alessandro; Kaita, Robert; Maingi, Rajesh

2016-10-01

Microgranule injection is a versatile means for investigating edge plasmas in fusion devices. Employing a dual bladed rotary turbine, carbon microgranules ranging in diameter from 300 - 700 microns are radially injected into NSTX-U discharges at approximately 50 m/sec. Utilizing multiple high speed camera views, a 3D reconstruction of the injection geometry is created which characterizes the ablation rate and granule trajectory. By coupling this with a neutral gas shielding (NGS) ablation model, the granule mass deposition profile can be determined. Simulation projects a depositional barycenter near the pedestal shoulder for H-mode discharges, and 20 cm inboard of the LCFS for L-mode discharges. Spectroscopic measurements of this localized particle source can be used to characterize impurity transport within the discharge, and potentially allows for direct measurement of the safety factor profile (q). In addition, the transient pressure peaking resultant from injection into H-mode plasmas can also result in the prompt triggering of an edge localized mode (ELM). Work supported by DOE Contract No. DE-AC02-09CH11466.

CW injection locking for long-term stability of frequency combs

NASA Astrophysics Data System (ADS)

Williams, Charles; Quinlan, Franklyn; Delfyett, Peter J.

2009-05-01

Harmonically mode-locked semiconductor lasers with external ring cavities offer high repetition rate pulse trains while maintaining low optical linewidth via long cavity storage times. Continuous wave (CW) injection locking further reduces linewidth and stabilizes the optical frequencies. The output can be stabilized long-term with the help of a modified Pound-Drever-Hall feedback loop. Optical sidemode suppression of 36 dB has been shown, as well as RF supermode noise suppression of 14 dB for longer than 1 hour. In addition to the injection locking of harmonically mode-locked lasers requiring an external frequency source, recent work shows the viability of the injection locking technique for regeneratively mode-locked lasers, or Coupled Opto-Electronic Oscillators (COEO).

Ultra-performance liquid chromatography/tandem mass spectrometric quantification of structurally diverse drug mixtures using an ESI-APCI multimode ionization source.

PubMed

Yu, Kate; Di, Li; Kerns, Edward; Li, Susan Q; Alden, Peter; Plumb, Robert S

2007-01-01

We report in this paper an ultra-performance liquid chromatography/tandem mass spectrometric (UPLC(R)/MS/MS) method utilizing an ESI-APCI multimode ionization source to quantify structurally diverse analytes. Eight commercial drugs were used as test compounds. Each LC injection was completed in 1 min using a UPLC system coupled with MS/MS multiple reaction monitoring (MRM) detection. Results from three separate sets of experiments are reported. In the first set of experiments, the eight test compounds were analyzed as a single mixture. The mass spectrometer was switching rapidly among four ionization modes (ESI+, ESI-, APCI-, and APCI+) during an LC run. Approximately 8-10 data points were collected across each LC peak. This was insufficient for a quantitative analysis. In the second set of experiments, four compounds were analyzed as a single mixture. The mass spectrometer was switching rapidly among four ionization modes during an LC run. Approximately 15 data points were obtained for each LC peak. Quantification results were obtained with a limit of detection (LOD) as low as 0.01 ng/mL. For the third set of experiments, the eight test compounds were analyzed as a batch. During each LC injection, a single compound was analyzed. The mass spectrometer was detecting at a particular ionization mode during each LC injection. More than 20 data points were obtained for each LC peak. Quantification results were also obtained. This single-compound analytical method was applied to a microsomal stability test. Compared with a typical HPLC method currently used for the microsomal stability test, the injection-to-injection cycle time was reduced to 1.5 min (UPLC method) from 3.5 min (HPLC method). The microsome stability results were comparable with those obtained by traditional HPLC/MS/MS.

Injected mass deposition thresholds for lithium granule instigated triggering of edge localized modes on EAST

NASA Astrophysics Data System (ADS)

Lunsford, R.; Sun, Z.; Maingi, R.; Hu, J. S.; Mansfield, D.; Xu, W.; Zuo, G. Z.; Diallo, A.; Osborne, T.; Tritz, K.; Canik, J.; Huang, M.; Meng, X. C.; Gong, X. Z.; Wan, B. N.; Li, J. G.; the EAST Team

2018-03-01

The ability of an injected lithium granule to promptly trigger an edge localized mode (ELM) has been established in multiple experiments. By horizontally injecting granules ranging in diameter from 200 microns to 1 mm in diameter into the low field side of EAST H-mode discharges we have determined that granules with diameter  >600 microns are successful in triggering ELMs more than 95% of the time. It was also demonstrated that below 600 microns the triggering efficiency decreased roughly with granule size. Granules were radially injected from the outer midplane with velocities ~80 m s-1 into EAST upper single null discharges with an ITER like tungsten monoblock divertor. These granules were individually tracked throughout their injection cycle in order to determine their efficacy at triggering an ELM. For those granules of sufficient size, ELM triggering was a prompt response to granule injection. By simulating the granule injection with an experimentally benchmarked neutral gas shielding (NGS) model, the ablatant mass deposition required to promptly trigger an ELM is calculated and the fractional mass deposition is determined.

Fast ion beta limit measurements by collimated neutron detection in MST plasmas

NASA Astrophysics Data System (ADS)

Capecchi, William; Anderson, Jay; Bonofiglo, Phillip; Kim, Jungha; Sears, Stephanie

2015-11-01

Fast ion orbits in the reversed field pinch (RFP) are well ordered and classically confined despite magnetic field stochasticity generated by multiple tearing modes. Classical TRANSP modeling of a 1MW tangentially injected hydrogen neutral beam in MST deuterium plasmas predicts a core-localized fast ion density that can be up to 25% of the electron density and a fast ion beta of many times the local thermal beta. However, neutral particle analysis of an NBI-driven mode (presumably driven by a fast ion pressure gradient) shows mode-induced transport of core-localized fast ions and a saturated fast ion density. The TRANSP modeling is presumed valid until the onset of the beam-driven mode and gives an initial estimate of the volume-averaged fast ion beta of 1-2% (local core value up to 10%). A collimated neutron detector for fusion product profile measurements will be used to determine the spatial distribution of fast ions, allowing for a first measurement of the critical fast-ion pressure gradient required for mode destabilization. Testing/calibration data and initial fast-ion profiles will be presented. Characterization of both the local and global fast ion beta will be done for deuterium beam injection into deuterium plasmas for comparison to TRANSP predictions. Work supported by US DOE.

Integrated exhaust and electrically heated particulate filter regeneration systems

DOEpatents

Gonze, Eugene V.; Paratore, Jr., Michael J.

2013-01-08

A system includes a particulate matter (PM) filter that includes multiple zones. An electrical heater includes heater segments that are associated with respective ones of the zones. The electrical heater is arranged upstream from and proximate with the PM filter. A post-fuel injection system injects fuel into at least one of a cylinder of an engine and an exhaust system. A control module is configured to operate in a first mode that includes activating the electrical heater to heat exhaust of the engine. The control module is also configured to operate in a second mode that includes activating the post-injection system to heat the exhaust. The control module selectively operates in at least one of the first mode and the second mode.

Analysis of a Rocket Based Combined Cycle Engine during Rocket Only Operation

NASA Technical Reports Server (NTRS)

Smith, T. D.; Steffen, C. J., Jr.; Yungster, S.; Keller, D. J.

1998-01-01

The all rocket mode of operation is a critical factor in the overall performance of a rocket based combined cycle (RBCC) vehicle. However, outside of performing experiments or a full three dimensional analysis, there are no first order parametric models to estimate performance. As a result, an axisymmetric RBCC engine was used to analytically determine specific impulse efficiency values based upon both full flow and gas generator configurations. Design of experiments methodology was used to construct a test matrix and statistical regression analysis was used to build parametric models. The main parameters investigated in this study were: rocket chamber pressure, rocket exit area ratio, percent of injected secondary flow, mixer-ejector inlet area, mixer-ejector area ratio, and mixer-ejector length-to-inject diameter ratio. A perfect gas computational fluid dynamics analysis was performed to obtain values of vacuum specific impulse. Statistical regression analysis was performed based on both full flow and gas generator engine cycles. Results were also found to be dependent upon the entire cycle assumptions. The statistical regression analysis determined that there were five significant linear effects, six interactions, and one second-order effect. Two parametric models were created to provide performance assessments of an RBCC engine in the all rocket mode of operation.

Mini-cavity plasma core reactors for dual-mode space nuclear power/propulsion systems. M.S. Thesis

NASA Technical Reports Server (NTRS)

Chow, S.

1976-01-01

A mini-cavity plasma core reactor is investigated for potential use in a dual-mode space power and propulsion system. In the propulsive mode, hydrogen propellant is injected radially inward through the reactor solid regions and into the cavity. The propellant is heated by both solid driver fuel elements surrounding the cavity and uranium plasma before it is exhausted out the nozzle. The propellant only removes a fraction of the driver power, the remainder is transferred by a coolant fluid to a power conversion system, which incorporates a radiator for heat rejection. Neutronic feasibility of dual mode operation and smaller reactor sizes than those previously investigated are shown to be possible. A heat transfer analysis of one such reactor shows that the dual-mode concept is applicable when power generation mode thermal power levels are within the same order of magnitude as direct thrust mode thermal power levels.

Ion beam analysis of C-13 and deuterium deposition in DIII-D and their removal by in-situ oxygen baking

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

Wampler, W. R.; Allen, S. L.; Brooks, N. H.

An experiment was conducted in DIII-D to examine carbon deposition when a secondary separatrix is near the wall. The magnetic configuration for this experiment was a biased double-null, similar to that foreseen for ITER. C-13 methane was injected toroidally symmetrically near the secondary separatrix into ELMy H-mode deuterium plasmas. The resulting deposition of C-13 was determined by nuclear reaction analysis. These results show that very little of the injected C-13 was deposited at the primary separatrix, whereas a large fraction of injected C-13 was deposited close to the point of injection near the secondary separatrix. Six of the tiles weremore » put back into DIII-D, where they were baked at 350-360 degrees C for 2 h at similar to 1 kPa in a 20% O-2/80% He gas mixture. Subsequent ion beam analysis of these tiles showed that about 21% of the C-13 and 54% of the deuterium were removed by the bake.« less

Theoretical analysis and simulation study of the deep overcompression mode of velocity bunching for a comblike electron bunch train

NASA Astrophysics Data System (ADS)

Wang, Dan; Yan, Lixin; Du, YingChao; Huang, Wenhui; Gai, Wei; Tang, Chuanxiang

2018-02-01

Premodulated comblike electron bunch trains are used in a wide range of research fields, such as for wakefield-based particle acceleration and tunable radiation sources. We propose an optimized compression scheme for bunch trains in which a traveling wave accelerator tube and a downstream drift segment are together used as a compressor. When the phase injected into the accelerator tube for the bunch train is set to ≪-10 0 ° , velocity bunching occurs in a deep overcompression mode, which reverses the phase space and maintains a velocity difference within the injected beam, thereby giving rise to a compressed comblike electron bunch train after a few-meter-long drift segment; we call this the deep overcompression scheme. The main benefits of this scheme are the relatively large phase acceptance and the uniformity of compression for the bunch train. The comblike bunch train generated via this scheme is widely tunable: For the two-bunch case, the energy and time spacings can be continuously adjusted from +1 to -1 MeV and from 13 to 3 ps, respectively, by varying the injected phase of the bunch train from -22 0 ° to -14 0 ° . Both theoretical analysis and beam dynamics simulations are presented to study the properties of the deep overcompression scheme.

Method for operating a spark-ignition, direct-injection internal combustion engine

DOEpatents

Narayanaswamy, Kushal; Koch, Calvin K.; Najt, Paul M.; Szekely, Jr., Gerald A.; Toner, Joel G.

2015-06-02

A spark-ignition, direct-injection internal combustion engine is coupled to an exhaust aftertreatment system including a three-way catalytic converter upstream of an NH3-SCR catalyst. A method for operating the engine includes operating the engine in a fuel cutoff mode and coincidentally executing a second fuel injection control scheme upon detecting an engine load that permits operation in the fuel cutoff mode.

Residence time distribution measurements in a pilot-scale poison tank using radiotracer technique.

PubMed

Pant, H J; Goswami, Sunil; Samantray, J S; Sharma, V K; Maheshwari, N K

2015-09-01

Various types of systems are used to control the reactivity and shutting down of a nuclear reactor during emergency and routine shutdown operations. Injection of boron solution (borated water) into the core of a reactor is one of the commonly used methods during emergency operation. A pilot-scale poison tank was designed and fabricated to simulate injection of boron poison into the core of a reactor along with coolant water. In order to design a full-scale poison tank, it was desired to characterize flow of liquid from the tank. Residence time distribution (RTD) measurement and analysis was adopted to characterize the flow dynamics. Radiotracer technique was applied to measure RTD of aqueous phase in the tank using Bromine-82 as a radiotracer. RTD measurements were carried out with two different modes of operation of the tank and at different flow rates. In Mode-1, the radiotracer was instantaneously injected at the inlet and monitored at the outlet, whereas in Mode-2, the tank was filled with radiotracer and its concentration was measured at the outlet. From the measured RTD curves, mean residence times (MRTs), dead volume and fraction of liquid pumped in with time were determined. The treated RTD curves were modeled using suitable mathematical models. An axial dispersion model with high degree of backmixing was found suitable to describe flow when operated in Mode-1, whereas a tanks-in-series model with backmixing was found suitable to describe flow of the poison in the tank when operated in Mode-2. The results were utilized to scale-up and design a full-scale poison tank for a nuclear reactor. Copyright © 2015 Elsevier Ltd. All rights reserved.

Self-injection locked blue laser

NASA Astrophysics Data System (ADS)

Donvalkar, Prathamesh S.; Savchenkov, Anatoliy; Matsko, Andrey

2018-04-01

We demonstrate a 446.5 nm GaN semiconductor laser with sub-MHz linewidth. The linewidth reduction is achieved by locking the laser to a magnesium fluoride whispering gallery mode resonator characterized with 109 quality factor. Self-injection locking ensures single longitudinal mode operation of the laser.

Remote heterodyne millimeter-wave over fiber based OFDM-PON with master-to-slave injected dual-mode colorless FPLD pair.

PubMed

Chen, Hsiang-Yu; Chi, Yu-Chieh; Lin, Gong-Ru

2015-08-24

A remote heterodyne millimeter-wave (MMW) carrier at 47.7 GHz over fiber synthesized with the master-to-slave injected dual-mode colorless FPLD pair is proposed, which enables the future connection between the wired fiber-optic 64-QAM OFDM-PON at 24 Gb/s with the MMW 4-QAM OFDM wireless network at 2 Gb/s. Both the single- and dual-mode master-to-slave injection-locked colorless FPLD pairs are compared to optimize the proposed 64-QAM OFDM-PON. For the unamplified single-mode master, the slave colorless FPLD successfully performs the 64-QAM OFDM data at 24 Gb/s with EVM, SNR and BER of 8.5%, 21.5 dB and 2.9 × 10(-3), respectively. In contrast, the dual-mode master-to-slave injection-locked colorless FPLD pair with amplified and unfiltered master can transmit 64-QAM OFDM data at 18 Gb/s over 25-km SMF to provide EVM, SNR and BER of 8.2%, 21.8 dB and 2.2 × 10(-3), respectively. For the dual-mode master-to-slave injection-locked colorless FPLD pair, even though the modal dispersion occurred during 25-km SMF transmission makes it sacrifice the usable OFDM bandwidth by only 1 GHz, which guarantees the sufficient encoding bitrate for the optically generated MMW carrier to implement the fusion of MMW wireless LAN and DWDM-PON with cost-effective and compact architecture. As a result, the 47.7-GHz MMW carrier remotely beat from the dual-mode master-to-slave injection-locked colorless FPLD pair exhibits an extremely narrow bandwidth of only 0.48 MHz. After frequency down-conversion operation, the 47.7-GHz MMW carrier successfully delivers 4-QAM OFDM data up to 2 Gb/s with EVM, SNR and BER of 33.5%, 9.51 dB and 1.4 × 10(-3), respectively.

Pulse evolution and mode selection characteristics in a TEA-CO2 laser perturbed by injection of external radiation

NASA Technical Reports Server (NTRS)

Flamant, P. H.; Menzies, R. T.; Kavaya, M. J.; Oppenheim, U. P.

1983-01-01

A grating-tunable TEA-CO2 laser with an unstable resonator cavity, modified to allow injection of CW CO2 laser radiation at the resonant transition line by means of an intracavity NaCl window, has been used to study the coupling requirements for generation of single frequency pulses. The width and shape of the mode selection region, and the dependence of the gain-switched spike buildup time and the pulse shapes on the intensity and detuning frequency of the injected radiation are reported. Comparisons of the experimental results with previously reported mode selection behavior are discussed.

Spectral modification of the laser emission of a terahertz quantum cascade laser induced by broad-band double pulse injection seeding

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

Markmann, Sergej, E-mail: sergej.markmann@ruhr-uni-bochum.de; Nong, Hanond, E-mail: nong.hanond@ruhr-uni-bochum.de; Hekmat, Negar

2015-09-14

We demonstrate by injection seeding that the spectral emission of a terahertz (THz) quantum cascade laser (QCL) can be modified with broad-band THz pulses whose bandwidths are greater than the QCL bandwidth. Two broad-band THz pulses delayed in time imprint a modulation on the single THz pulse spectrum. The resulting spectrum is used to injection seed the THz QCL. By varying the time delay between the THz pulses, the amplitude distribution of the QCL longitudinal modes is modified. By applying this approach, the QCL emission is reversibly switched from multi-mode to single mode emission.

Substorm Related ULF waves Observed in the Magnetosphere by BD-IES and Van Allan Probes

NASA Astrophysics Data System (ADS)

Zong, Q.

2017-12-01

By using the data return from the BD-IES instrument onboard an inclined (55°) geosynchronous orbit (IGSO) satellite together with geo-transfer orbit (GTO) Van Allen Probe A&B satellite, we analysis a substorm related ULF waves occurred on Feb 5, 2016 in the dawnside of the magnetosphere. Immediately after the substorm injection followed by energetic electron drift echoes, the electron flux was clearly and strongly varying on the ULF wave time scale. It is found that both toroidal and poloidal mode ULF waves with a period of 320 s. During the substorm injection, the IES onboard IGSO is outbound while both Van Allen Probe A&B satellites are inbound. This configuration of multiple satellite trajectories provides an unique opportunity to investigate substorm related ULF waves. When substorm injections are observed simultaneously with multiple spacecraft, they help elucidate potential mechanisms for particle transport and energization, a topic of great importance for understanding and modeling the magnetosphere. Two possible scenaria on ULF wave triggering are discussed: fast-mode compressional waves -driven field line resonance and ULF wave growth through drift resonance.

High frequency pacing of edge localized modes by injection of lithium granules in DIII-D H-mode discharges

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

Bortolon, A.; Maingi, R.; Mansfield, D. K.

A newly installed Lithium Granule Injector (LGI) was used to pace edge localized modes (ELM) in DIII-D. ELM pacing efficiency was studied injecting lithium granules of nominal diameter 0.3–0.9mm, speed of 50–120 m s -1 and average injection rates up to 100 Hz for 0.9mm granules and up to 700 Hz for 0.3mm granules. The efficiency of ELM triggering was found to depend strongly on size of the injected granules, with triggering efficiency close to 100% obtained with 0.9mm diameter granules, lower with smaller sizes, and weakly depending on granule velocity. Robust ELM pacing was demonstrated in ITER-like plasmas formore » the entire shot length, at ELM frequencies 3–5 times larger than the ‘natural’ ELM frequency observed in reference discharges. Within the range of ELM frequencies obtained, the peak ELM heat flux at the outer strike point was reduced with increasing pacing frequency. The peak heat flux reduction at the inner strike point appears to saturate at high pacing frequency. Lithium was found in the plasma core, with a concurrent reduction of metallic impurities and carbon. Altogether, high frequency ELM pacing using the lithium granule injection appears to be compatible with both H-mode energy confinement and attractive H-mode pedestal characteristics, but further assessment is need« less

High frequency pacing of edge localized modes by injection of lithium granules in DIII-D H-mode discharges

DOE PAGES

Bortolon, A.; Maingi, R.; Mansfield, D. K.; ...

2016-04-08

A newly installed Lithium Granule Injector (LGI) was used to pace edge localized modes (ELM) in DIII-D. ELM pacing efficiency was studied injecting lithium granules of nominal diameter 0.3–0.9mm, speed of 50–120 m s -1 and average injection rates up to 100 Hz for 0.9mm granules and up to 700 Hz for 0.3mm granules. The efficiency of ELM triggering was found to depend strongly on size of the injected granules, with triggering efficiency close to 100% obtained with 0.9mm diameter granules, lower with smaller sizes, and weakly depending on granule velocity. Robust ELM pacing was demonstrated in ITER-like plasmas formore » the entire shot length, at ELM frequencies 3–5 times larger than the ‘natural’ ELM frequency observed in reference discharges. Within the range of ELM frequencies obtained, the peak ELM heat flux at the outer strike point was reduced with increasing pacing frequency. The peak heat flux reduction at the inner strike point appears to saturate at high pacing frequency. Lithium was found in the plasma core, with a concurrent reduction of metallic impurities and carbon. Altogether, high frequency ELM pacing using the lithium granule injection appears to be compatible with both H-mode energy confinement and attractive H-mode pedestal characteristics, but further assessment is need« less

Comprehensive analysis of pharmaceutical products using simultaneous mixed-mode (ion-exchange/reversed-phase) and hydrophilic interaction liquid chromatography.

PubMed

Kazarian, Artaches A; Nesterenko, Pavel N; Soisungnoen, Phimpha; Burakham, Rodjana; Srijaranai, Supalax; Paull, Brett

2014-08-01

Liquid chromatographic assays were developed using a mixed-mode column coupled in sequence with a hydrophilic interaction liquid chromatography column to allow the simultaneous comprehensive analysis of inorganic/organic anions and cations, active pharmaceutical ingredients, and excipients (carbohydrates). The approach utilized dual sample injection and valve-mediated column switching and was based upon a single high-performance liquid chromatography gradient pump. The separation consisted of three distinct sequential separation mechanisms, namely, (i) ion-exchange, (ii) mixed-mode interactions under an applied dual gradient (reversed-phase/ion-exchange), and (iii) hydrophilic interaction chromatography. Upon first injection, the Scherzo SS C18 column (Imtakt) provided resolution of inorganic anions and cations under isocratic conditions, followed by a dual organic/salt gradient to elute active pharmaceutical ingredients and their respective organic counterions and potential degradants. At the top of the mixed-mode gradient (high acetonitrile content), the mobile phase flow was switched to a preconditioned hydrophilic interaction liquid chromatography column, and the standard/sample was reinjected for the separation of hydrophilic carbohydrates, some of which are commonly known excipients in drug formulations. The approach afforded reproducible separation and resolution of up to 23 chemically diverse solutes in a single run. The method was applied to investigate the composition of commercial cough syrups (Robitussin®), allowing resolution and determination of inorganic ions, active pharmaceutical ingredients, excipients, and numerous well-resolved unknown peaks. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Impact of perturbative, non-axisymmetric impurity fueling on Alcator C-Mod H-modes

NASA Astrophysics Data System (ADS)

Reinke, M. L.; Lore, J. D.; Terry, J.; Brunner, D.; LaBombard, B.; Lipschultz, B.; Hubbard, A.; Hughes, J. W.; Mumgaard, R.; Pitts, R. A.

2017-12-01

Experiments on Alcator C-Mod have been performed to investigate the impact of toroidally localized impurity injection on H-mode exhaust scenarios. Results help to inform sub-divertor gas injector designs, in particular that of the ITER machine, for which this work was primarily undertaken. In repeated EDA H-modes, the amount of N2 injected into the private flux region was scanned up to levels which strongly impacted normalized energy confinement, H98, and led to an H/L back-transition. Repeated scans increased the toroidal peaking of the gas injection, reducing from five equally spaced locations to a single toroidal and poloidal injector. Results show the impact on the pedestal and core plasma is similar between all cases as long as the total gas injection rate is held constant. An influence on toroidally localized impurity spectroscopy is shown, demonstrating a complication in using such data in interpreting experiments and supporting boundary modeling in cases where there are localized extrinsic or intrinsic impurity sources. These results, along with prior work in this area on Alcator C-Mod, form a comprehensive set of L-mode and H-mode data to be used for validation of 3D boundary physics codes.

Elimination of fuel pressure fluctuation and multi-injection fuel mass deviation of high pressure common-rail fuel injection system

NASA Astrophysics Data System (ADS)

Li, Pimao; Zhang, Youtong; Li, Tieshuan; Xie, Lizhe

2015-03-01

The influence of fuel pressure fluctuation on multi-injection fuel mass deviation has been studied a lot, but the fuel pressure fluctuation at injector inlet is still not eliminated efficiently. In this paper, a new type of hydraulic filter consisting of a damping hole and a chamber is developed for elimination of fuel pressure fluctuation and multi-injection fuel mass deviation. Linear model of the improved high pressure common-rail system(HPCRS) including injector, the pipe connecting common-rail with injector and the hydraulic filter is built. Fuel pressure fluctuation at injector inlet, on which frequency domain analysis is conducted through fast Fourier transformation, is acquired at different target pressure and different damping hole diameter experimentally. The linear model is validated and can predict the natural frequencies of the system. Influence of damping hole diameter on fuel pressure fluctuation is analyzed qualitatively based on the linear model, and it can be inferred that an optimal diameter of the damping hole for elimination of fuel pressure fluctuation exists. Fuel pressure fluctuation and fuel mass deviation under different damping hole diameters are measured experimentally, and it is testified that the amplitude of both fuel pressure fluctuation and fuel mass deviation decreases first and then increases with the increasing of damping hole diameter. The amplitude of main injection fuel mass deviation can be reduced by 73% at most under pilot-main injection mode, and the amplitude of post injection fuel mass deviation can be reduced by 92% at most under main-post injection mode. Fuel mass of a single injection increases with the increasing of the damping hole diameter. The hydraulic filter proposed by this research can be potentially used to eliminate fuel pressure fluctuation at injector inlet and improve the stability of HPCRS fuel injection.

Towards a 1 MW, 170 GHz gyrotron design for fusion application

NASA Astrophysics Data System (ADS)

Kumar, Anil; Kumar, Nitin; Singh, Udaybir; Bhattacharya, Ranajoy; Yadav, Vivek; Sinha, A. K.

2013-03-01

The electrical design of different components of 1 MW, 170 GHz gyrotron such as, magnetron injection gun, cylindrical interaction cavity and collector and RF window is presented in this article. Recently, a new project related to the development of 170 GHz, 1 MW gyrotron has been started for the Indian Tokamak. TE34,10 mode is selected as the operating mode after studied the problem of mode competition. The triode type geometry is selected for the design of magnetron injection gun (MIG) to achieve the required beam parameters. The maximum transverse velocity spread of 3.28% at the velocity ratio of 1.34 is obtained in simulations for a 40 A, 80 kV electron beam. The RF output power of more than 1 MW with 36.5% interaction efficiency without depressed collector is predicted by simulation in single-mode operation at 170 GHz frequency. The simulated single-stage depressed collector of the gyrotron predicted the overall device efficiencies >55%. Due to the very good thermal conductivity and very weak dependency of the dielectric parameters on temperature, PACVD diamond is selected for window design for the transmission of RF power. The in-house developed code MIGSYN and GCOMS are used for initial geometry design of MIG and mode selection respectively. Commercially available simulation tools MAGIC and ANSYS are used for beam-wave interaction and mechanical analysis respectively.

Stability of the mode-locking regime in tapered quantum-dot lasers

NASA Astrophysics Data System (ADS)

Bardella, P.; Drzewietzki, L.; Rossetti, M.; Weber, C.; Breuer, S.

2018-02-01

We study numerically and experimentally the role of the injection current and reverse bias voltage on the pulse stability of tapered, passively mode-locked, Quantum Dot (QD) lasers. By using a multi-section delayed differential equation and introducing in the model the QD inhomogenous broadening, we are able to predict the onset of leading and trailing edge instabilities in the emitted pulse trains and to identify specific trends of stability in dependence on the laser biasing conditions. The numerical results are confirmed experimentally trough amplitude and timing stability analysis of the pulses.

Current profile redistribution driven by neutral beam injection in a reversed-field pinch

NASA Astrophysics Data System (ADS)

Parke, E.; Anderson, J. K.; Brower, D. L.; Den Hartog, D. J.; Ding, W. X.; Johnson, C. A.; Lin, L.

2016-05-01

Neutral beam injection in reversed-field pinch (RFP) plasmas on the Madison Symmetric Torus [Dexter et al., Fusion Sci. Technol. 19, 131 (1991)] drives current redistribution with increased on-axis current density but negligible net current drive. Internal fluctuations correlated with tearing modes are observed on multiple diagnostics; the behavior of tearing mode correlated structures is consistent with flattening of the safety factor profile. The first application of a parametrized model for island flattening to temperature fluctuations in an RFP allows inferrence of rational surface locations for multiple tearing modes. The m = 1, n = 6 mode is observed to shift inward by 1.1 ± 0.6 cm with neutral beam injection. Tearing mode rational surface measurements provide a strong constraint for equilibrium reconstruction, with an estimated reduction of q0 by 5% and an increase in on-axis current density of 8% ± 5%. The inferred on-axis current drive is consistent with estimates of fast ion density using TRANSP [Goldston et al., J. Comput. Phys. 43, 61 (1981)].

Effects of quadratic coupling and squeezed vacuum injection in an optomechanical cavity assisted with a Bose-Einstein condensate

NASA Astrophysics Data System (ADS)

Dalafi, A.; Naderi, M. H.; Motazedifard, Ali

2018-04-01

We investigate theoretically a hybrid system consisting of a Bose-Einstein condensate (BEC) trapped inside a laser-driven membrane-in-the-middle optomechanical cavity assisted with squeezed vacuum injection whose moving membrane interacts both linearly and quadratically with the radiation pressure of the cavity. It is shown that such a hybrid system is very suitable for generating strong quadrature squeezing in the mechanical mode of the membrane and the Bogoliubov mode of the BEC in the unresolved sideband regime. More interestingly, by choosing a suitable sign for the quadratic optomechanical coupling (QOC), one can achieve a very high degree of squeezing in the mechanical mode and a strong entanglement between the mechanical and atomic modes without the necessity of using squeezed light injection. Furthermore, the QOC changes the effective oscillation frequencies of both the mechanical and the atomic modes and affects their relaxation times. It can also make the system switch from optical bistability to tristability.

1.2-ps mode-locked semiconductor optical amplifier fiber laser pulses generated by 60-ps backward dark-optical comb injection and soliton compression.

PubMed

Lin, Gong-Ru; Chiu, I-Hsiang; Wu, Ming-Chung

2005-02-07

Optically harmonic mode-locking of a semiconductor optical amplifier fiber laser (SOAFL) induced by backward injecting a dark-optical comb is demonstrated for the first time. The dark-optical comb with 60-ps pulsewidth is generated from a Mach-Zehnder modulator, which is driven by an electrical comb at a DC offset of 0.3Vn. Theoretical simulation indicates that the backward injection of dark-optical comb results in a narrow gain window of 60 ps within one modulating period, providing a cross-gainmodulation induced mode-locking in the SOAFL with a shortest pulsewidth of 15 ps at repetition frequency of 1 GHz. The mode-locked SOAFL pulsewidth can be slightly shortened to 10.8 ps with a 200m-long dispersion compensating fiber. After nonlinearly soliton compression in a 5km-long single mode fiber, the pulsewidth, linewidth and time-bandwidth product become 1.2 ps, 2.06 nm and 0.31, respectively.

Two-mode mazer injected with V-type three-level atoms

NASA Astrophysics Data System (ADS)

Liang, Wen-Qing; Zhang, Zhi-Ming; Xie, Sheng-Wu

2003-12-01

The properties of the two-mode mazer operating on V-type three-level atoms are studied. The effect of the one-atom pumping on the two modes of the cavity field in number-state is asymmetric, that is, the atom emits a photon into one mode with some probability and absorbs a photon from the other mode with some other probability. This effect makes the steady-state photon distribution and the steady-state photon statistics asymmetric for the two modes. The diagram of the probability currents for the photon distribution, given by the analysis of the master equation, reveals that there is no detailed balance solution for the master equation. The computations show that the photon statistics of one mode or both modes can be sub-Poissonian, that the two modes can have anticorrelation or correlation, that the photon statistics increases with the increase of thermal photons and that the resonant position and strength of the photon statistics are influenced by the ratio of the two coupling strengths of the two modes. These properties are also discussed physically.

Experimental Investigation of Fuel-Reactivity Controlled Compression Ignition (RCCI) Combustion Mode in a Multi-Cylinder, Light-Duty Diesel Engine

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

Cho, Kukwon; Curran, Scott; Prikhodko, Vitaly Y

2011-01-01

An experimental study was performed to provide the combustion and emission characteristics resulting from fuel-reactivity controlled compression ignition (RCCI) combustion mode utilizing dual-fuel approach in a light-duty, multi-cylinder diesel engine. In-cylinder fuel blending using port fuel injection of gasoline before intake valve opening (IVO) and early-cycle, direct injection of diesel fuel was used as the charge preparation and fuel blending strategy. In order to achieve the desired auto-ignition quality through the stratification of the fuel-air equivalence ratio ( ), blends of commercially available gasoline and diesel fuel were used. Engine experiments were performed at an engine speed of 2300rpm andmore » an engine load of 4.3bar brake mean effective pressure (BMEP). It was found that significant reduction in both nitrogen oxide (NOx) and particulate matter (PM) was realized successfully through the RCCI combustion mode even without applying exhaust gas recirculation (EGR). However, high carbon monoxide (CO) and hydrocarbon (HC) emissions were observed. The low combustion gas temperature during the expansion and exhaust processes seemed to be the dominant source of high CO emissions in the RCCI combustion mode. The high HC emissions during the RCCI combustion mode could be due to the increased combustion quenching layer thickness as well as the -stratification at the periphery of the combustion chamber. The slightly higher brake thermal efficiency (BTE) of the RCCI combustion mode was observed than the other combustion modes, such as the conventional diesel combustion (CDC) mode, and single-fuel, premixed charge compression ignition (PCCI) combustion mode. The parametric study of the RCCI combustion mode revealed that the combustion phasing and/or the peak cylinder pressure rise rate of the RCCI combustion mode could be controlled by several physical parameters premixed ratio (rp), intake swirl intensity, and start of injection (SOI) timing of directly injected fuel unlike other low temperature combustion (LTC) strategies.« less

Injection locking of a two-mode electron oscillator with close frequencies

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

Starodubova, E. N.; Usacheva, S. A.; Ryskin, N. M.

2015-03-15

Theory of injection locking is developed for a two-mode electron maser with close frequencies, when the driving signal affects both modes. There exist two regimes of phase locking in which either first or second mode dominates. Hard transitions between the two regimes are observed with variation of the driving frequency. The results of numerical simulations are presented for the case of driving by a signal with linear frequency chirp, as well as by a signal with sinusoidal frequency modulation. The effect of bifurcation delay is observed with the increase of chirp rate.

Power- or frequency-driven hysteresis for continuous-wave optically injected distributed-feedback semiconductor lasers.

PubMed

Blin, Stéphane; Vaudel, Olivier; Besnard, Pascal; Gabet, Renaud

2009-05-25

Bistabilities between a steady (or pulsating, chaotic) and different pulsating regimes are investigated for an optically injected semi-conductor laser. Both numerical and experimental studies are reported for continuous-wave single-mode semiconductor distributed-feedback lasers emitting at 1.55 microm. Hysteresis are driven by either changing the optically injected power or the frequency difference between both lasers. The effect of the injected laser pumping rate is also examined. Systematic mappings of the possible laser outputs (injection locking, bimodal, wave mixing, chaos or relaxation oscillations) are carried out. At small pumping rates (1.2 times threshold), only locking and bimodal regimes are observed. The extent of the bistable area is either 11 dB or 35 GHz, depending on the varying parameters. At high pumping rates (4 times threshold), numerous injection regimes are observed. Injection locking and its bistabilities are also reported for secondary longitudinal modes.

Wideband-frequency tunable optoelectronic oscillator based on injection locking to an electronic oscillator.

PubMed

Fleyer, Michael; Sherman, Alexander; Horowitz, Moshe; Namer, Moshe

2016-05-01

We experimentally demonstrate a wideband-frequency tunable optoelectronic oscillator (OEO) based on injection locking of the OEO to a tunable electronic oscillator. The OEO cavity does not contain a narrowband filter and its frequency can be tuned over a broad bandwidth of 1 GHz. The injection locking is based on minimizing the injected power by adjusting the frequency of one of the OEO cavity modes to be approximately equal to the frequency of the injected signal. The phase noise that is obtained in the injection-locked OEO is similar to that obtained in a long-cavity self-sustained OEO. Although the cavity length of the OEO was long, the spurious modes were suppressed due to the injection locking without the need to use a narrowband filter. The spurious level was significantly below that obtained in a self-sustained OEO after inserting a narrowband electronic filter with a Q-factor of 720 into the cavity.

The Growing Popularity of Prescription Opioid Injection in Downtown Montréal: New Challenges for Harm Reduction

PubMed Central

Roy, Élise; Arruda, Nelson; Bourgois, Phillipe

2011-01-01

Starting in 2007, a 2-year study based on ethnographic methodology was carried out downtown Montréal, Canada. A thematic analysis of observational and interview-based notes was conducted. Illicit prescription opioid (PO) use was widespread among street-based participants. Injection was the main mode of PO administration observed among users. Some injection practices such as “doing a wash” could pose new challenges in terms of prevention of infections. More research is needed to examine the role of illicit PO use in the development of opiate addiction and to better understand drug-using contexts that put PO users at risk of infections. The study’s limitations are noted. PMID:21370963

Fishbone Mode Excited by Deeply Trapped Energetic Beam Ions in EAST

NASA Astrophysics Data System (ADS)

Zheng, Ting; Wu, Bin; Xu, Liqing; Hu, Chundong; Zang, Qing; Ding, Siye; Li, Yingying; Wu, Xingquan; Wang, Jinfang; Shen, Biao; Zhong, Guoqiang; Li, Hao; Shi, Tonghui; EAST Team

2016-06-01

This paper describes the fishbone mode phenomena during the injection of high-power neutral beams in EAST (Experimental Advanced Superconducting Tokamak). The features of the fishbone mode are presented. The change in frequency of the mode during a fishbone burst is from 1 kHz to 6 kHz. The nonlinear behavior of the fishbone mode is analyzed by using a prey-predator model, which is consistent with the experimental results. This model indicates that the periodic oscillations of the fishbone mode always occur near the critical value of fast ion beta. Furthermore, the neutral beam analysis for the discharge is done by using the NUBEAM module of the TRANSP code. According to the numerical simulation results and theoretical calculation, it can be concluded that the fishbone mode is driven by the deeply trapped energetic beam ions in EAST. supported by the National Magnetic Confinement Fusion Science Program of China (Nos. 2013GB101001, 2014DFG61950 and 2013GB112003) and National Natural Science Foundation of China (Nos. 11175211 and 11275233)

Modular separation-based fiber-optic sensors for remote in situ monitoring.

PubMed

Dickens, J; Sepaniak, M

2000-02-01

A modular separation-based fiber-optic sensor (SBFOS) with an integrated electronically controlled injection device is described for potential use in remote environmental monitoring. An SBFOS is a chemical monitor that integrates the separation selectivity and versatility afforded by capillary electrophoresis with the remote and high sensitivity capabilities of fiber-optic-based laser-induced fluorescence sensing. The detection module of the SBFOS accommodates all essential sensing components for dual-optical fiber, on-capillary fluorescence detection. An injection module, similar to injection platforms on micro-analysis chips, is also integrated to the SBFOS. The injection module allows for electronically controlled injection of the sample onto the separation capillary. The design and operational characteristics of the modular SBFOS are discussed in this paper. A micellar electrokinetic capillary chromatography mode of separation is employed to evaluate the potential of the sensor for in situ monitoring of neutral toxins (aflatoxins). The analytical figures of merit for the modular SBFOS include analysis times of between 5 and 10 min, separation efficiencies of approximately 10(4) theoretical plates, detection limits for aflatoxins in the mid-to-low nanomolar range, and controllable operation that results in sensor performance that is largely immune to sample matrix effects.

Mixed mode fuel injector with individually moveable needle valve members

DOEpatents

Stewart, Chris; Chockley, Scott A.; Ibrahim, Daniel R.; Lawrence, Keith; Tomaseki, Jay; Azam, Junru H.; Tian, Steven Ye; Shafer, Scott F.

2004-08-03

A fuel injector includes a homogenous charge nozzle outlet set and a conventional nozzle outlet set controlled respectively, by first and second needle valve members. One of the needle valve members moves to an open position while the other needle valve member remains stationary for a homogeneous charge injection event. The former needle valve member stays stationary while the other needle valve member moves to an open position for a conventional injection event. One of the needle valve members is at least partially positioned in the other needle valve member. Thus, the injector can perform homogeneous charge injection events, conventional injection events, or even a mixed mode having both types of injection events in a single engine cycle.

Asymmetric valley-resolved beam splitting and incident modes in slanted graphene junctions

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

Hsieh, S. H.; Chu, C. S.

2016-01-18

Electron injection into a graphene sheet through a slanted armchair graphene nanoribbon (AGNR) is investigated. An incident mode, or subband, in the AGNR is valley-unpolarized. Our attention is on the valley-resolved nature of the injected electron beams and its connection to the incident mode. It is known for a normal injection that an incident mode will split symmetrically into two valley-resolved beams of equal intensity. We show, in contrast, that slanted injections result in asymmetric valley-resolved beam splitting. The most asymmetric beam splitting cases, when one of the valley-resolved beams has basically disappeared, are found and the condition derived. Thismore » is shown not due to trigonal warping because it holds even in the low incident energy regime, as long as collimation allows. These most asymmetric beam splitting cases occur at energies within an energy interval near and include the subband edge of an incident mode. The physical picture is best illustrated by a projection of the slanted AGNR subband states onto that of the 2D graphene sheet. It follows that the disappearing of a valley-resolved beam coincides with the situation that the group velocities of the projected states in the corresponding valley are in backward directions.« less

Mode-locking observation of a CO2 laser by intracavity plasma injection

NASA Astrophysics Data System (ADS)

John, P. K.; Dembinski, M.

1980-06-01

A TEA CO2 laser was simultaneously Q-switched and mode-locked when an underdense plasma was injected into the cavity. The plasma was produced in an electromagnetic shock tube. Plasma density and temperature were N sub e of approximately 10 to the 17th/cu cm and T sub e of approximately 2 eV, respectively. Phase perturbation of the cavity due to the time dependent plasma refractive index could account for the observed mode-locking.

Continuous-Wave Single-Frequency Operation of Fabry-Perot Laser Diodes by Self-Injection Phase Locking Using Feedback from a Fiber Bragg Grating

NASA Technical Reports Server (NTRS)

Duerksen, Gary L.; Krainak, Michael A.

1998-01-01

Single-frequency operation of uncoated Fabry-Perot laser diodes is demonstrated by phase- locking the laser oscillations through self-injection seeding with feedback from a fiber Bragg grating. By precisely tuning the laser temperature so that an axial-mode coincides with the short-wavelength band edge of the grating, the phase of the feedback is made conjugate to that of the axial mode, locking the phase of the laser oscillations to that mode.

Influence of injection mode on transport properties in kilometer-scale three-dimensional discrete fracture networks

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

Hyman, Jeffrey De'Haven; Painter, S. L.; Viswanathan, H.

We investigate how the choice of injection mode impacts transport properties in kilometer-scale three-dimensional discrete fracture networks (DFN). The choice of injection mode, resident and flux-weighted, is designed to mimic different physical phenomena. It has been hypothesized that solute plumes injected under resident conditions evolve to behave similarly to solutes injected under flux-weighted conditions. Previously, computational limitations have prohibited the large-scale simulations required to investigate this hypothesis. We investigate this hypothesis by using a high-performance DFN suite, dfnWorks, to simulate flow in kilometer-scale three-dimensional DFNs based on fractured granite at the Forsmark site in Sweden, and adopt a Lagrangian approachmore » to simulate transport therein. Results show that after traveling through a pre-equilibrium region, both injection methods exhibit linear scaling of the first moment of travel time and power law scaling of the breakthrough curve with similar exponents, slightly larger than 2. Lastly, the physical mechanisms behind this evolution appear to be the combination of in-network channeling of mass into larger fractures, which offer reduced resistance to flow, and in-fracture channeling, which results from the topology of the DFN.« less

Influence of injection mode on transport properties in kilometer-scale three-dimensional discrete fracture networks

DOE PAGES

Hyman, Jeffrey De'Haven; Painter, S. L.; Viswanathan, H.; ...

2015-09-12

We investigate how the choice of injection mode impacts transport properties in kilometer-scale three-dimensional discrete fracture networks (DFN). The choice of injection mode, resident and flux-weighted, is designed to mimic different physical phenomena. It has been hypothesized that solute plumes injected under resident conditions evolve to behave similarly to solutes injected under flux-weighted conditions. Previously, computational limitations have prohibited the large-scale simulations required to investigate this hypothesis. We investigate this hypothesis by using a high-performance DFN suite, dfnWorks, to simulate flow in kilometer-scale three-dimensional DFNs based on fractured granite at the Forsmark site in Sweden, and adopt a Lagrangian approachmore » to simulate transport therein. Results show that after traveling through a pre-equilibrium region, both injection methods exhibit linear scaling of the first moment of travel time and power law scaling of the breakthrough curve with similar exponents, slightly larger than 2. Lastly, the physical mechanisms behind this evolution appear to be the combination of in-network channeling of mass into larger fractures, which offer reduced resistance to flow, and in-fracture channeling, which results from the topology of the DFN.« less

RF Behavior of Cylindrical Cavity Based 240 GHz, 1 MW Gyrotron for Future Tokamak System

NASA Astrophysics Data System (ADS)

Kumar, Nitin; Singh, Udaybir; Bera, Anirban; Sinha, A. K.

2017-11-01

In this paper, we present the RF behavior of conventional cylindrical interaction cavity for 240 GHz, 1 MW gyrotron for futuristic plasma fusion reactors. Very high-order TE mode is searched for this gyrotron to minimize the Ohmic wall loading at the interaction cavity. The mode selection process is carried out rigorously to analyze the mode competition and design feasibility. The cold cavity analysis and beam-wave interaction computation are carried out to finalize the cavity design. The detail parametric analyses for interaction cavity are performed in terms of mode stability, interaction efficiency and frequency. In addition, the design of triode type magnetron injection gun is also discussed. The electron beam parameters such as velocity ratio and velocity spread are optimized as per the requirement at interaction cavity. The design studies presented here confirm the realization of CW, 1 MW power at 240 GHz frequency at TE46,17 mode.

Rapid Quantitation of Ascorbic and Folic Acids in SRM 3280 Multivitamin/Multielement Tablets using Flow-Injection Tandem Mass Spectrometry

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

Bhandari, Deepak; Kertesz, Vilmos; Van Berkel, Gary J

RATIONALE: Ascorbic acid (AA) and folic acid (FA) are water-soluble vitamins and are usually fortified in food and dietary supplements. For the safety of human health, proper intake of these vitamins is recommended. Improvement in the analysis time required for the quantitative determination of these vitamins in food and nutritional formulations is desired. METHODS: A simple and fast (~5 min) in-tube sample preparation was performed, independently for FA and AA, by mixing extraction solvent with a powdered sample aliquot followed by agitation, centrifugation, and filtration to recover an extract for analysis. Quantitative detection was achieved by flow-injection (1 L injectionmore » volume) electrospray ionization tandem mass spectrometry (ESI-MS/MS) in negative ion mode using the method of standard addition. RESULTS: Method of standard addition was employed for the quantitative estimation of each vitamin in a sample extract. At least 2 spiked and 1 non-spiked sample extract were injected in triplicate for each quantitative analysis. Given an injection-to-injection interval of approximately 2 min, about 18 min was required to complete the quantitative estimation of each vitamin. The concentration values obtained for the respective vitamins in the standard reference material (SRM) 3280 using this approach were within the statistical range of the certified values provided in the NIST Certificate of Analysis. The estimated limit of detections of FA and AA were 13 and 5.9 ng/g, respectively. CONCLUSIONS: Flow-injection ESI-MS/MS was successfully applied for the rapid quantitation of FA and AA in SRM 3280 multivitamin/multielement tablets.« less

Space tug economic analysis study. Volume 2: Tug concepts analysis. Appendix: Tug design and performance data base

NASA Technical Reports Server (NTRS)

1972-01-01

The tug design and performance data base for the economic analysis of space tug operation are presented. A compendium of the detailed design and performance information from the data base is developed. The design data are parametric across a range of reusable space tug sizes. The performance curves are generated for selected point designs of expendable orbit injection stages and reusable tugs. Data are presented in the form of graphs for various modes of operation.

Plasma profile evolution during disruption mitigation via massive gas injection on MAST

NASA Astrophysics Data System (ADS)

Thornton, A. J.; Gibson, K. J.; Chapman, I. T.; Harrison, J. R.; Kirk, A.; Lisgo, S. W.; Lehnen, M.; Martin, R.; Scannell, R.; Cullen, A.; the MAST Team

2012-06-01

Massive gas injection (MGI) is one means of ameliorating disruptions in future devices such as ITER, where the stored energy in the plasma is an order of magnitude larger than in present-day devices. The penetration of the injected impurities during MGI in MAST is diagnosed using a combination of high-speed (20 kHz) visible imaging and high spatial (1 cm) and temporal (0.1 ms) resolution Thomson scattering (TS) measurements of the plasma temperature and density. It is seen that the rational surfaces, in particular q = 2, are the critical surfaces for disruption mitigation. The TS data shows the build-up of density on rational surfaces in the edge cooling period of the mitigation, leading to the collapse of the plasma in a thermal quench. The TS data are confirmed by the visible imaging, which shows filamentary structures present at the start of the thermal quench. The filamentary structures have a topology which matches that of a q = 2 field line in MAST, suggesting that they are located on the q = 2 surface. Linearized magnetohydrodynamic stability analysis using the TS profiles suggests that the large density build-up on the rational surfaces drives modes within the plasma which lead to the thermal quench. The presence of such modes is seen experimentally in the form of magnetic fluctuations on Mirnov coils and the growth of an n = 1 toroidal mode in the period prior to the thermal quench. These results support the observations of other machines that the 2/1 mode is the likely trigger for the thermal quench in a mitigated disruption and suggests that the mitigation process in spherical tokamaks is similar to that in conventional aspect ratio devices.

Space tug economic analysis study. Volume 1: Executive summary

NASA Technical Reports Server (NTRS)

1972-01-01

An economic analysis of space tug operations is presented. The space tug is defined as any liquid propulsion stage under 100,000 pounds propellant loading that is flown from the space shuttle cargo bay. Two classes of vehicles are the orbit injection stages and reusable space tugs. The vehicle configurations, propellant combinations, and operating modes used for the study are reported. The summary contains data on the study approach, results, conclusions, and recommendations.

Droplet-based microfluidic flow injection system with large-scale concentration gradient by a single nanoliter-scale injection for enzyme inhibition assay.

PubMed

Cai, Long-Fei; Zhu, Ying; Du, Guan-Sheng; Fang, Qun

2012-01-03

We described a microfluidic chip-based system capable of generating droplet array with a large scale concentration gradient by coupling flow injection gradient technique with droplet-based microfluidics. Multiple modules including sample injection, sample dispersion, gradient generation, droplet formation, mixing of sample and reagents, and online reaction within the droplets were integrated into the microchip. In the system, nanoliter-scale sample solution was automatically injected into the chip under valveless flow injection analysis mode. The sample zone was first dispersed in the microchannel to form a concentration gradient along the axial direction of the microchannel and then segmented into a linear array of droplets by immiscible oil phase. With the segmentation and protection of the oil phase, the concentration gradient profile of the sample was preserved in the droplet array with high fidelity. With a single injection of 16 nL of sample solution, an array of droplets with concentration gradient spanning 3-4 orders of magnitude could be generated. The present system was applied in the enzyme inhibition assay of β-galactosidase to preliminarily demonstrate its potential in high throughput drug screening. With a single injection of 16 nL of inhibitor solution, more than 240 in-droplet enzyme inhibition reactions with different inhibitor concentrations could be performed with an analysis time of 2.5 min. Compared with multiwell plate-based screening systems, the inhibitor consumption was reduced 1000-fold. © 2011 American Chemical Society

Plasma density injection and flow during coaxial helicity injection in a tokamak

NASA Astrophysics Data System (ADS)

Hooper, E. B.

2018-02-01

Whole device, resistive MHD simulations of spheromaks and tokamaks have used a large diffusion coefficient that maintains a nearly constant density throughout the device. In the present work, helicity and plasma are coinjected into a low-density plasma in a tokamak with a small diffusion coefficient. As in previous simulations [Hooper et al., Phys. Plasmas 20, 092510 (2013)], a flux bubble is formed, which expands to fill the tokamak volume. The injected plasma is non-uniform inside the bubble. The flow pattern is analyzed; when the simulation is not axisymmetric, an n = 1 mode on the surface of the bubble generates leakage of plasma into the low-density volume. Closed flux is generated following injection, as in experiments and previous simulations. The result provides a more detailed physics analysis of the injection, including density non-uniformities in the plasma that may affect its use as a startup plasma [Raman et al., Phys. Rev. Lett. 97, 175002 (2006)].

Feasibility of Retrograde Ureteral Contrast Injection to Guide Ultrasonographic Percutaneous Renal Access in the Nondilated Collecting System.

PubMed

Usawachintachit, Manint; Tzou, David T; Mongan, John; Taguchi, Kazumi; Weinstein, Stefanie; Chi, Thomas

2017-02-01

Ultrasound-guided percutaneous nephrolithotomy (PCNL) has become increasingly utilized. Patients with nondilated collecting systems represent a challenge: the target calix is often difficult to visualize. Here we report pilot study results for retrograde ultrasound contrast injection to aid in percutaneous renal access during ultrasound-guided PCNL. From April to July 2016, consecutive patients over the age of 18 years with nondilated collecting systems on preoperative imaging who presented for PCNL were enrolled. B-mode ultrasound imaging was compared with contrast-enhanced mode with simultaneous retrograde injection of Optison™ via an ipsilateral ureteral catheter. Five patients (four males and one female) with renal stones underwent PCNL with retrograde ultrasound contrast injection during the study period. Mean body mass index was 28.3 ± 5.6 kg/m 2 and mean stone size was 24.5 ± 12.0 mm. Under B-mode ultrasound, all patients demonstrated nondilated renal collecting systems that appeared as hyperechoic areas, where it was difficult to identify a target calix for puncture. Retrograde contrast injection facilitated delineation of all renal calices initially difficult to visualize under B-mode ultrasound. Renal puncture was then performed effectively in all cases with a mean puncture time of 55.4 ± 44.8 seconds. All PCNL procedures were completed without intraoperative complications and no adverse events related to ultrasound contrast injection occurred. Retrograde ultrasound contrast injection as an aide for renal puncture during PCNL is a feasible technique. By improving visualization of the collecting system, it facilitates needle placement in challenging patients without hydronephrosis. Future larger scale studies comparing its use to standard ultrasound-guided technique will be required to validate this concept.

Multiple injection mode with or without repeated sample injections: Strategies to enhance productivity in countercurrent chromatography.

PubMed

Müller, Marco; Wasmer, Katharina; Vetter, Walter

2018-06-29

Countercurrent chromatography (CCC) is an all liquid based separation technique typically used for the isolation and purification of natural compounds. The simplicity of the method makes it easy to scale up CCC separations from analytical to preparative and even industrial scale. However, scale-up of CCC separations requires two different instruments with varying coil dimensions. Here we developed two variants of the CCC multiple injection mode as an alternative to increase the throughput and enhance productivity of a CCC separation when using only one instrument. The concept is based on the parallel injection of samples at different points in the CCC column system and the simultaneous separation using one pump only. The wiring of the CCC setup was modified by the insertion of a 6-port selection valve, multiple T-pieces and sample loops. Furthermore, the introduction of storage sample loops enabled the CCC system to be used with repeated injection cycles. Setup and advantages of both multiple injection modes were shown by the isolation of the furan fatty acid 11-(3,4-dimethyl-5-pentylfuran-2-yl)-undecanoic acid (11D5-EE) from an ethyl ester oil rich in 4,7,10,13,16,19-docosahexaenoic acid (DHA-EE). 11D5-EE was enriched in one step from 1.9% to 99% purity. The solvent consumption per isolated amount of analyte could be reduced by ∼40% compared to increased throughput CCC and by ∼5% in the repeated multiple injection mode which also facilitated the isolation of the major compound (DHA-EE) in the sample. Copyright © 2018 Elsevier B.V. All rights reserved.

Long-distance multi-channel bidirectional chaos communication based on synchronized VCSELs subject to chaotic signal injection

NASA Astrophysics Data System (ADS)

Xie, Yi-Yuan; Li, Jia-Chao; He, Chao; Zhang, Zhen-Dong; Song, Ting-Ting; Xu, Chang-Jun; Wang, Gui-Jin

2016-10-01

A novel long-distance multi-channel bidirectional chaos communication system over multiple paths based on two synchronized 1550 nm vertical-cavity surface-emitting lasers (VCSELs) is proposed and studied theoretically. These two responding VCSELs (R-VCSELs) can output similar chaotic signals served as chaotic carrier in two linear polarization (LP) modes with identical signal injection from a driving VCSEL (D-VCSEL), which is subject to optical feedback and optical injection, simultaneously. Through the numerical simulations, high quality chaos synchronization between the two R-VCSELs can be obtained. Besides, the effects of varied qualities of chaos synchronization on communication performances in 20 km single mode fiber (SMF) channels are investigated by regulating different internal parameters mismatch after adopting chaos masking (CMS) technique. With the decrease of the maximum cross correlation coefficient (Max-C) between the two R-VCSELs, the bit error rate (BER) of decoded message increase. Meanwhile, the BER can still be less than 10-9 when the Max-C degrades to 0.982. Based on high quality synchronization, when the dispersion compensating fiber (DCF) links are introduced, 4n messages of 10 Gbit/s can transmit in 180 km SMF channels over n coupling paths, bidirectionally and simultaneously. Thorough tests are carried out with detailed analysis, demonstrating long-distance, multi-channel, bidirectional chaos communication based on VCSELs with chaotic signal injection.

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

Slipchenko, S. O., E-mail: serghpl@mail.ioffe.ru; Podoskin, A. A.; Vinokurov, D. A.

Radiative characteristics of semiconductor stripe-contact lasers operating under quenching conditions of Fabry-Perot-mode lasing are studied. It is found that reversible turning off of Fabry-Perot-mode lasing is caused by switching to closed-mode lasing. Radiative characteristics of the closed mode are controlled by the mode structure with the close-to-zero loss for radiation output, which covers the entire crystal. The main threshold conditions of closed-mode lasing are a decrease in interband absorption in the passive region and an increase in the modal gain of the closed-mode lasing line. It is shown that a decrease in interband absorption in the passive region can bemore » provided by both spontaneous emission from the injection region and lasing-mode photons. An increase in the modal gain of the closed-mode lasing line is provided by shifting the energy minima of the conduction band and maxima of the valence band of the injection region with respect to the energy bands of the passive region.« less

Discriminant analysis to predict the occurrence of ELMS in H-mode discharges

NASA Astrophysics Data System (ADS)

Kardaun, O. J. W. F.; Itoh, S.-I.; Itoh, K.; Kardaun, J. W. P. F.

1993-08-01

After an exposition of its theoretical background, discriminant analysis is applied to the H-mode confinement database to find the region in plasma parameter space in which H-mode with small ELM's (Edge Localized Modes) is likely to occur. The boundary of this region is determined by the condition that the probability of appearance of such a type of H-mode, as a function of the plasma parameters, should be larger than some threshold value and larger than the corresponding probability for other types of H-mode (i.e., H-mode without ELM's or with giant ELM's). In practice, the discrimination has been performed for the ASDEX, JET and JFT-2M tokamaks using four instantaneous plasma parameters (injected power Pinj, magnetic field Bt, plasma current Ip and line averaged electron density ne) and taking also memory effects of the plasma and the distance between the plasma and the wall into account, while using variables that are normalized with respect to machine size. Generally speaking, it is found that there is a substantial overlap between the region of H-mode with small ELM's and the region of the two other types of H-mode. However, the ELM-free and the giant ELM H-modes relatively rarely appear in the region, that, according to the analysis, is allocated to small ELM's. A reliable production of H-mode with only small ELM's seems well possible by choosing this regime in parameter space. In the present study, it was not attempted to arrive at a unified discrimination across the machines. So, projection from one machine to another remains difficult, and a reliable determination of the region where small ELM's occur still requires a training sample from the device under consideration.

Chemical composition and source of fine and nanoparticles from recent direct injection gasoline passenger cars: Effects of fuel and ambient temperature

NASA Astrophysics Data System (ADS)

Fushimi, Akihiro; Kondo, Yoshinori; Kobayashi, Shinji; Fujitani, Yuji; Saitoh, Katsumi; Takami, Akinori; Tanabe, Kiyoshi

2016-01-01

Particle number, mass, and chemical compositions (i.e., elemental carbon (EC), organic carbon (OC), elements, ions, and organic species) of fine particles emitted from four of the recent direct injection spark ignition (DISI) gasoline passenger cars and a port fuel injection (PFI) gasoline passenger car were measured under Japanese official transient mode (JC08 mode). Total carbon (TC = EC + OC) dominated the particulate mass (90% on average). EC dominated the TC for both hot and cold start conditions. The EC/TC ratios were 0.72 for PFI and 0.88-1.0 (average = 0.92) for DISI vehicles. A size-resolved chemical analysis of a DISI car revealed that the major organic components were the C20-C28 hydrocarbons for both the accumulation-mode particles and nanoparticles. Contribution of engine oil was estimated to be 10-30% for organics and the sum of the measured elements. The remaining major fraction likely originated from gasoline fuel. Therefore, it is suggested that soot (EC) also mainly originated from the gasoline. In experiments using four fuels at three ambient temperatures, the emission factors of particulate mass were consistently higher with regular gasoline than with premium gasoline. This result suggest that the high content of less-volatile compounds in fuel increase particulate emissions. These results suggest that focusing on reducing fuel-derived EC in the production process of new cars would effectively reduce particulate emission from DISI cars.

Rapid characterization of chemical markers for discrimination of Moutan Cortex and its processed products by direct injection-based mass spectrometry profiling and metabolomic method.

PubMed

Li, Chao-Ran; Li, Meng-Ning; Yang, Hua; Li, Ping; Gao, Wen

2018-06-01

Processing of herbal medicines is a characteristic pharmaceutical technique in Traditional Chinese Medicine, which can reduce toxicity and side effect, improve the flavor and efficacy, and even change the pharmacological action entirely. It is significant and crucial to perform a method to find chemical markers for differentiating herbal medicines in different processed degrees. The aim of this study was to perform a rapid and reasonable method to discriminate Moutan Cortex and its processed products, and to reveal the characteristics of chemical components depend on chemical markers. Thirty batches of Moutan Cortex and its processed products, including 11 batches of Raw Moutan Cortex (RMC), 9 batches of Moutan Cortex Tostus (MCT) and 10 batches of Moutan Cortex Carbonisatus (MCC), were directly injected in electrospray ionization quadrupole time-of-flight mass spectrometry (ESI-QTOF MS) for rapid analysis in positive and negative mode. Without chromatographic separation, each run was completed within 3 min. The raw MS data were automatically extracted by background deduction and molecular feature (MF) extraction algorithm. In negative mode, a total of 452 MFs were obtained and then pretreated by data filtration and differential analysis. After that, the filtered 85 MFs were treated by principal component analysis (PCA) to reduce the dimensions. Subsequently, a partial least squares discrimination analysis (PLS-DA) model was constructed for differentiation and chemical markers detection of Moutan Cortex in different processed degrees. The positive mode data were treated as same as those in negative mode. RMC, MCT and MCC were successfully classified. Moreover, 14 and 3 chemical markers from negative and positive mode respectively, were screened by the combination of their relative peak areas and the parameter variable importance in the projection (VIP) values in PLS-DA model. The content changes of these chemical markers were employed in order to illustrate chemical changes of Moutan Cortex after processed. These results showed that the proposed method which combined non-targeted metabolomics analysis with multivariate statistics analysis is reasonable and effective. It could not only be applied to discriminate herbal medicines and their processing products, but also to reveal the characteristics of chemical components during processing. Copyright © 2018. Published by Elsevier GmbH.

Current profile redistribution driven by neutral beam injection in a reversed-field pinch

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

Parke, E.; Department of Physics, University of Wisconsin-Madison 1150 University Ave., Madison, Wisconsin 53706; Anderson, J. K.

2016-05-15

Neutral beam injection in reversed-field pinch (RFP) plasmas on the Madison Symmetric Torus [Dexter et al., Fusion Sci. Technol. 19, 131 (1991)] drives current redistribution with increased on-axis current density but negligible net current drive. Internal fluctuations correlated with tearing modes are observed on multiple diagnostics; the behavior of tearing mode correlated structures is consistent with flattening of the safety factor profile. The first application of a parametrized model for island flattening to temperature fluctuations in an RFP allows inferrence of rational surface locations for multiple tearing modes. The m = 1, n = 6 mode is observed to shift inward by 1.1 ± 0.6 cm withmore » neutral beam injection. Tearing mode rational surface measurements provide a strong constraint for equilibrium reconstruction, with an estimated reduction of q{sub 0} by 5% and an increase in on-axis current density of 8% ± 5%. The inferred on-axis current drive is consistent with estimates of fast ion density using TRANSP [Goldston et al., J. Comput. Phys. 43, 61 (1981)].« less

Bounce frequency fishbone analysis

NASA Astrophysics Data System (ADS)

White, Roscoe; Fredrickson, Eric; Chen, Liu

2002-11-01

Large amplitude bursting modes are observed on NSTX, which are identified as bounce frequency fishbone modes(PDX Group, Princeton Plasma Physics Lab, Phys Rev. Lett) 50, 891 (1983)^,(L. Chen, R. B. White, and M. N. Rosenbluth Phys Rev. Lett) 52, 1122 (1984). The identification is carried out using numerical equilibria obtained from TRANSP( R. V. Budny, M. G. Bell A. C. Janos et al), Nucl Fusion 35, 1497 (1995) and the numerical guiding center code ORBIT( R.B. White, Phys. Fluids B 2)(4), 845 (1990). These modes are important for high energy particle distributions which have large average bounce angle, such as the nearly tangentially injected beam ions in NSTX and isotropic alpha particle distributions. They are particularly important in high q low shear advanced plasma scenarios. Different ignited plasma scenarios are investigated with these modes in view.

Transformation of fault slip modes in laboratory experiments

NASA Astrophysics Data System (ADS)

Martynov, Vasilii; Alexey, Ostapchuk; Markov, Vadim

2017-04-01

Slip mode of crust fault can vary because of many reasons. It's well known that fault structure, material of fault gouge, pore fluid et al. in many ways determines slip modes from creep and slow slip events to mega-earthquakes [1-3]. Therefore, the possibility of fault slip transformation due to external action is urgent question. There is popular and developing approach of fluid injection into central part of fault. The phenomenon of earthquakes induced due to pumping of water was investigated on small and large scales [4, 5]. In this work the laboratory experiments were conducted to study the evolution of the experimental fault slip when changing the properties of the interstitial fluid. The scheme of experiments is the classical slider-model set-up, in which the block under the shear force slips along the interface. In our experiments the plexiglas block 8x8x3 cm3 in size was put on the plexiglas base. The contact of the blocks was filled with a thin layer (about 3 mm thick) of a granular material. The normal load varied from 31 to 156 kPa. The shear load was applied through a spring with stiffness 60 kN/m, and the rate of spring deformation was 20 or 5 mcm/s. Two parameters were recorded during experiments: the shear force acting on the upper block (with an accuracy of 1 N) and its displacement relatively the base (with an accuracy of 0.1 μm). The gouge was composed of quartz sand (97.5%) and clay (2.5%). As a moisturizer were used different fluids with viscosity varying from 1 to 103 mPa x s. Different slip modes were simulated during slider-experiments. In our experiments slip mode is the act of instability manifested in an increase of slip velocity and a drop of shear stress acting on a movable block. The amplitude of a shear stress drop and the peak velocity of the upper block were chosen as the characteristics of the slip mode. In the laboratory experiments, slip events of one type can be achieved either as regularly recurring (regular mode) or as random stochastic (irregular mode). To investigate regularities of transformation and get statistically correct results we simulated only regular mode. During the experiments, after the establishment of a regular mode, we injected fluid into central part of interblock contact. Varying injecting fluid we were able both to decrease and increase amplitude of events. For example, after injection of 1 mPa x s fluid (water) in gouge, moisturized with 100 mPa x s fluid (ethylene glycol), peak velocity rose by almost an order. But after injection of an aqueous solution of starch (big viscosity and dilatant rheology) amplitude decreased 1.5 times and then slip almost completely stabilized. It's probably connected with the viscosity of solution, which increases with quick shift. Time of injection also has the significant impact on the possibility of transformation and its efficiency. Thus, it is well known that if the time of injection is in the vicinity of loss of strength moment, any external influence only initiates slip events. Preliminary results of our laboratory experiments show that the fluid injection can both reduce the part of deformation energy going seismic wave radiation, and to increase it. The most effective action observed in experinemts with injection of dilatant fluid. Findings demonstrate the prospectivity of further research in this direction. The work was supported by the Russian Science Foundation (Grant No. 16-17-00095) [1] Fagereng A., Sibson R.H. 2010. Melange rheology and seismic style. Geology. Vol.38, p.751-754. [2] Kocharyan G.G., et al. 2017. A study of different fault slip modes governed by the gouge material composition in laboratory experiments. Geophys. J. Int. Vol.208, p. 521-528. [3] Yamashita T. 2013. Generation of slow slip coupled with tremor due to fluid flow along a fault. Geophys. J. Int. Vol.193, p.375-393. [4] Guglielmi Y., et. al. 2015. Seismicity triggered by fluid injection-induced aseismic slip. Science. Vol.348, p.1224-1226. [5] Wei S., et al. 2015. The 2012 Brawley swarm triggered by injection-induced aseismic slip. EPSL. Vol. 422, p.115-122.

First injection of ketamine among young injection drug users (IDUs) in three U.S. cities

PubMed Central

Lankenau, Stephen E.; Sanders, Bill; Bloom, Jennifer Jackson; Hathazi, Dodi; Alarcon, Erica; Tortu, Stephanie; Clatts, Michael C.

2007-01-01

Ketamine, a dissociative anesthetic, has emerged as an increasingly common drug among subgroups of young injection drug users (IDUs) in cities across the United States. In-depth qualitative interviews were conducted with 213 young IDUs aged 16–28 years recruited in New York, New Orleans, and Los Angeles between 2004 and 2006. While some initiated injection drug use with ketamine, the drug was more frequently injected by IDUs with extensive polydrug using histories. IDUs initiating with ketamine commonly self-injected via an intramuscular mode of administration. The injection group provided crucial knowledge and material resources that enabled the injection event to occur, including ketamine, syringes, and injection skills. Injection paraphernalia was commonly shared during the first injection of ketamine, particularly vials of pharmaceutically-packaged liquid ketamine. Injection events infrequently occurred in a rave or club and more typically in a private home, which challenges ketamine’s designation as a ‘club’ drug. The first injection of ketamine was a noteworthy event since it introduced a novel drug or new mode of administration to be further explored by some, or exposed others to a drug to be avoided in the future. Risk reduction messages directed towards young IDUs should be expanded to include ketamine. PMID:16979848

Injected mass deposition thresholds for lithium granule instigated triggering of edge localized modes on EAST

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

Lunsford, R.; Sun, Zhen; Maingi, Rajesh

The ability of an injected lithium granule to promptly trigger an edge localized mode (ELM) has been established in multiple experiments. By horizontally injecting granules ranging in diameter from 200 microns to 1mm in diameter into the low field side of EAST H-mode discharges we have determined that granules with diameter > 600 microns are successful in triggering ELMs more than 95% of the time. Granules were radially injected from the outer midplane with velocities ~ 80 m/s into EAST upper-single null discharges with an ITER like tungsten monoblock divertor. ELM triggering was a prompt response to granule injection, andmore » for granules of a sufficient size there was no evidence of a "trigger lag" phenomenon as observed in full metal machines. We also demonstrated that the triggering efficiency decreased with granule size during dynamic size scans. These granules were individually tracked throughout their injection cycle in order to determine their efficacy at triggering an ELM. Furthermore, by simulating the granule injection with an experimentally benchmarked neutral gas shielding (NGS) model, the ablatant mass deposition required to promptly trigger an ELM is calculated and the fractional mass deposition is determined. Simulated 900 micron granules capable of triggering an ELM show a peaked mass deposition of 3.9 x 10 17 atoms per mm of penetration at a depth of approximately 5 cm past the separatrix.« less

Injected mass deposition thresholds for lithium granule instigated triggering of edge localized modes on EAST

DOE PAGES

Lunsford, R.; Sun, Zhen; Maingi, Rajesh; ...

2017-12-19

The ability of an injected lithium granule to promptly trigger an edge localized mode (ELM) has been established in multiple experiments. By horizontally injecting granules ranging in diameter from 200 microns to 1mm in diameter into the low field side of EAST H-mode discharges we have determined that granules with diameter > 600 microns are successful in triggering ELMs more than 95% of the time. Granules were radially injected from the outer midplane with velocities ~ 80 m/s into EAST upper-single null discharges with an ITER like tungsten monoblock divertor. ELM triggering was a prompt response to granule injection, andmore » for granules of a sufficient size there was no evidence of a "trigger lag" phenomenon as observed in full metal machines. We also demonstrated that the triggering efficiency decreased with granule size during dynamic size scans. These granules were individually tracked throughout their injection cycle in order to determine their efficacy at triggering an ELM. Furthermore, by simulating the granule injection with an experimentally benchmarked neutral gas shielding (NGS) model, the ablatant mass deposition required to promptly trigger an ELM is calculated and the fractional mass deposition is determined. Simulated 900 micron granules capable of triggering an ELM show a peaked mass deposition of 3.9 x 10 17 atoms per mm of penetration at a depth of approximately 5 cm past the separatrix.« less

The inductive, steady-state sustainment of stable spheromaks

NASA Astrophysics Data System (ADS)

Hossack, A. C.; Jarboe, T. R.; Morgan, K. D.; Sutherland, D. A.; Hansen, C. J.; Everson, C. J.; Penna, J. M.; Nelson, B. A.

2016-10-01

Inductive helicity injection current drive with imposed perturbations has led to the breakthrough of spheromak sustainment while maintaining stability. Sustained spheromaks show coherent, imposed plasma motion and low plasma-generated mode activity, indicating stability. Additionally, record current gain of 3.9 has been achieved with evidence of pressure confinement. The Helicity Injected Torus - Steady Inductive (HIT-SI) experiment studies efficient, steady-state current drive for magnetic confinement plasmas using a novel experimental method which is ideal for low aspect ratio, toroidal geometries and is compatible with closed flux surfaces. Analysis of surface magnetic probes indicates large n = 0 and 1 toroidal Fourier mode amplitudes and little energy in higher modes. Biorthogonal decomposition shows that almost all of the n = 1 energy is imposed by the injectors, rather than plasma-generated. Ion Doppler spectroscopy (IDS) measurements show coherent, imposed plasma motion of +/-2.5 cm in the region inside r 10 cm (a = 23 cm) and the size of the separate spheromak is consistent with that predicted by Imposed-dynamo Current Drive (IDCD). Coherent motion indicates that the spheromak is stable and a lack of plasma-generated n = 1 energy indicates that the maximum q is maintained below 1 for stability during sustainment.

Micro-focused Brillouin light scattering study of the magnetization dynamics driven by Spin Hall effect in a transversely magnetized NiFe nanowire

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

Madami, M., E-mail: marco.madami@fisica.unipg.it; Carlotti, G.; Gubbiotti, G.

2015-05-07

We employed micro-focused Brillouin light scattering to study the amplification of the thermal spin wave eigenmodes by means of a pure spin current, generated by the spin-Hall effect, in a transversely magnetized Pt(4 nm)/NiFe(4 nm)/SiO{sub 2}(5 nm) layered nanowire with lateral dimensions 500 × 2750 nm{sup 2}. The frequency and the cross section of both the center (fundamental) and the edge spin wave modes have been measured as a function of the intensity of the injected dc electric current. The frequency of both modes exhibits a clear redshift while their cross section is greatly enhanced on increasing the intensity of the injected dc. A threshold-like behaviormore » is observed for a value of the injected dc of 2.8 mA. Interestingly, an additional mode, localized in the central part of the nanowire, appears at higher frequency on increasing the intensity of the injected dc above the threshold value. Micromagnetic simulations were used to quantitatively reproduce the experimental results and to investigate the complex non-linear dynamics induced by the spin-Hall effect, including the modification of the spatial profile of the spin wave modes and the appearance of the extra mode above the threshold.« less

Modeling of lithium granule injection in NSTX using M3D-C1

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

Fil, A.; Kolemen, E.; Ferraro, N.

In this paper, we present simulations of pedestal control by lithium granule injection (LGI) in NSTX. A model for small granule ablation has been implemented in the M3D-C1 code (Jardin et al 2012 Comput. Sci. Discovery 5 014002), allowing the simulation of realistic lithium granule injections. 2D and 3D simulations of Li injections in NSTX H-mode plasmas are performed and the effect of granule size, injection angle and velocity on the pedestal gradient increase is studied. The amplitude of the local pressure perturbation caused by the granules is found to be highly dependent on the solid granule size. Adjusting themore » granule injection velocity allows one to inject more particles at the pedestal top. 3D simulations show the destabilization of high order MHD modes whose amplitude is directly linked to the localized pressure perturbation, which is found to depend on the toroidal localization of the granule density source.« less

Modeling of lithium granule injection in NSTX using M3D-C1

DOE PAGES

Fil, A.; Kolemen, E.; Ferraro, N.; ...

2017-04-06

In this paper, we present simulations of pedestal control by lithium granule injection (LGI) in NSTX. A model for small granule ablation has been implemented in the M3D-C1 code (Jardin et al 2012 Comput. Sci. Discovery 5 014002), allowing the simulation of realistic lithium granule injections. 2D and 3D simulations of Li injections in NSTX H-mode plasmas are performed and the effect of granule size, injection angle and velocity on the pedestal gradient increase is studied. The amplitude of the local pressure perturbation caused by the granules is found to be highly dependent on the solid granule size. Adjusting themore » granule injection velocity allows one to inject more particles at the pedestal top. 3D simulations show the destabilization of high order MHD modes whose amplitude is directly linked to the localized pressure perturbation, which is found to depend on the toroidal localization of the granule density source.« less

Parametric Oscillation, Frequency Mixing, and Injection Locking of Strongly Coupled Nanomechanical Resonator Modes.

PubMed

Seitner, Maximilian J; Abdi, Mehdi; Ridolfo, Alessandro; Hartmann, Michael J; Weig, Eva M

2017-06-23

We study locking phenomena of two strongly coupled, high quality factor nanomechanical resonator modes to a common parametric drive at a single drive frequency in different parametric driving regimes. By controlled dielectric gradient forces we tune the resonance frequencies of the flexural in-plane and out-of-plane oscillation of the high stress silicon nitride string through their mutual avoided crossing. For the case of the strong common parametric drive signal-idler generation via nondegenerate parametric two-mode oscillation is observed. Broadband frequency tuning of the very narrow linewidth signal and idler resonances is demonstrated. When the resonance frequencies of the signal and idler get closer to each other, partial injection locking, injection pulling, and complete injection locking to half of the drive frequency occurs depending on the pump strength. Furthermore, satellite resonances, symmetrically offset from the signal and idler by their beat note, are observed, which can be attributed to degenerate four-wave mixing in the highly nonlinear mechanical oscillations.

Human Mars Mission: Launch Window from Earth Orbit. Pt. 1

NASA Technical Reports Server (NTRS)

Young, Archie

1999-01-01

The determination of orbital window characteristics is of major importance in the analysis of human interplanetary missions and systems. The orbital launch window characteristics are directly involved in the selection of mission trajectories, the development of orbit operational concepts, and the design of orbital launch systems. The orbital launch window problem arises because of the dynamic nature of the relative geometry between outgoing (departure) asymptote of the hyperbolic escape trajectory and the earth parking orbit. The orientation of the escape hyperbola asymptotic relative to the earth is a function of time. The required hyperbola energy level also varies with time. In addition, the inertial orientation of the parking orbit is a function of time because of the perturbations caused by the Earth's oblateness. Thus, a coplanar injection onto the escape hyperbola can be made only at a point in time when the outgoing escape asymptote is contained by the plane of parking orbit. Even though this condition may be planned as a nominal situation, it will not generally represent the more probable injection geometry. The general case of an escape injection maneuver performed at a time other than the coplanar time will involve both a path angle and plane change and, therefore, a delta V penalty. Usually, because of the delta V penalty the actual departure injection window is smaller in duration than that determined by energy requirement alone. This report contains the formulation, characteristics, and test cases for five different launch window modes for Earth orbit. These modes are: 1) One impulsive maneuver from a Highly Elliptical Orbit (HEO); 2) Two impulsive maneuvers from a Highly Elliptical Orbit (HEO); 3) One impulsive maneuver from a Low Earth Orbit (LEO); 4) Two impulsive maneuvers form LEO; and 5) Three impulsive maneuvers form LEO. The formulation of these five different launch window modes provides a rapid means of generating realistic parametric data for space exploration studies. Also the formulation provides vector and geometrical data sufficient for use as a good starting point in detail trajectory analysis based on calculus of variations, steepest descent, or parameter optimization program techniques.

Human Exploration Missions Study Launch Window from Earth Orbit

NASA Technical Reports Server (NTRS)

Young, Archie

2001-01-01

The determination of orbital launch window characteristics is of major importance in the analysis of human interplanetary missions and systems. The orbital launch window characteristics are directly involved in the selection of mission trajectories, the development of orbit operational concepts, and the design of orbital launch systems. The orbital launch window problem arises because of the dynamic nature of the relative geometry between outgoing (departure) asymptote of the hyperbolic escape trajectory and the earth parking orbit. The orientation of the escape hyperbola asymptotic relative to earth is a function of time. The required hyperbola energy level also varies with time. In addition, the inertial orientation of the parking orbit is a function of time because of the perturbations caused by the Earth's oblateness. Thus, a coplanar injection onto the escape hyperbola can be made only at a point in time when the outgoing escape asymptote is contained by the plane of parking orbit. Even though this condition may be planned as a nominal situation, it will not generally represent the more probable injection geometry. The general case of an escape injection maneuver performed at a time other than the coplanar time will involve both a path angle and plane change and, therefore, a Delta(V) penalty. Usually, because of the Delta(V) penalty the actual departure injection window is smaller in duration than that determined by energy requirement alone. This report contains the formulation, characteristics, and test cases for five different launch window modes for Earth orbit. These modes are: (1) One impulsive maneuver from a Low Earth Orbit (LEO), (2) Two impulsive maneuvers from LEO, (3) Three impulsive maneuvers from LEO, (4) One impulsive maneuvers from a Highly Elliptical Orbit (HEO), (5) Two impulsive maneuvers from a Highly Elliptical Orbit (HEO) The formulation of these five different launch window modes provides a rapid means of generating realistic parametric data for space exploration studies. Also the formulation provides vector and geometrical data sufficient for use as a good starting point in detail trajectory analysis based on calculus of variations, steepest descent, or parameter optimization program techniques.

Applying short-duration pulses as a mean to enhance volatile organic compounds removal by air sparging

NASA Astrophysics Data System (ADS)

Ben Neriah, Asaf; Paster, Amir

2017-10-01

Application of short-duration pulses of high air pressure, to an air sparging system for groundwater remediation, was tested in a two-dimensional laboratory setup. It was hypothesized that this injection mode, termed boxcar, can enhance the remediation efficiency due to the larger ZOI and enhanced mixing which results from the pressure pulses. To test this hypothesis, flow and transport experiments were performed. Results confirm that cyclically applying short-duration pressure pulses may enhance contaminant cleanup. Comparing the boxcar to conventional continuous air-injection shows up to a three-fold increase in the single well radius of influence, dependent on the intensity of the short-duration pressure-pulses. The cleanup efficiency of Toluene from the water was 95% higher than that achieved under continuous injection with the same average conditions. This improvement was attributed to the larger zone of influence and higher average air permeability achieved in the boxcar mode, relative to continuous sparging. Mixing enhancement resultant from recurring pressure pulses was suggested as one of the mechanisms which enhance the contaminant cleanup. The application of a boxcar mode in an existing, multiwell, air sparging setup can be relatively straightforward: it requires the installation of an on-off valve in each of the injection-wells and a central control system. Then, turning off some of the wells, for a short-duration, result in a stepwise increase in injection pressure in the rest of the wells. It is hoped that this work will stimulate the additional required research and ultimately a field scale application of this new injection mode.

Experimental investigation of a reacting transverse jet in a high pressure oscillating vitiated crossflow

NASA Astrophysics Data System (ADS)

Fugger, Christopher A.

Staged combustion is one design approach in a gas turbine engine to reduce pollutant emission levels. In axially staged combustion, portions of the air and fuel are injected downstream of a lean premixed low NOx primary combustion zone. The gas residence time at elevated temperatures is decreased resulting in lower thermal NOx, and the reduced oxygen and high temperature vitiated primary zone flow further help to reduce pollutant emissions and quickly complete combustion. One implementation of axially staged combustion is transverse fuel jet injection. An important consideration for staged combustion systems, though, is how the primary and secondary combustion zones can couple through the acoustic resonances of the chamber. These couplings can lead to additional source terms that pump energy into the resonant acoustic field and help sustain the high-amplitude combustor pressure oscillations. An understanding of these couplings is important so that it may be possible to design a secondary combustion system that provides inherent damping to the combustor system. To systematically characterize the coupling of a reacting jet in unsteady crossflow in detail, the effects of an an unsteady pressure flowfield and an unsteady velocity flowfield are separately investigated. An optically accessible resonant combustion chamber was designed and built as part of this work to generate a standing wave unsteady vitiated crossflow at a chamber pressure of 0.9 MPa. The location of transverse jet injection corresponds to one of two locations, where one location is the pressure node and the other location the pressure anti-node of the resonant chamber acoustic mode. The injection location is optically accessible, and the dynamic interactions between the transverse jet flow and the 1st and 2nd axial combustor modes are measured using 10 kHz OH-PLIF and 2D PIV. This document analyzes five test cases: two non-reacting jets and three reacting jets. All cases correspond to jet injection near a pressure node of the 1st axial combustor mode, where the dominant flowfield fluctuations are a time-varying crossflow velocity. For the non-reacting jets, the nominal jet-to-crossflow momentum flux ratio is 19. For the reacting jets, the nominal jet-to-crossflow momentum flux ratio is 6. Two cross sectional planes parallel to the jet injection wall are investigated: 1 and 2.7 jet diameters from the jet injection wall. The combustor crossflow high frequency wall mounted pressure data is given for each test case. The velocity and OH-PLIF data is presented as instantaneous snapshots, time and phase averaged flowfields, modal decompositions using Proper Orthogonal Decomposition and Dynamic Mode Decomposition, and a jet cycle analysis relative to the crossflow acoustic cycle. Analysis of the five test cases shows that the jet cross sectional velocity and OH-PLIF dynamics display a multitude of dynamics. These are often organized into shear layer dynamics and wake dynamics, but are not mutually exclusive. For large unsteady crossflow velocity oscillations at the 1st axial combustor mode, both dynamics show strong organization at the unsteady crossflow frequency. Deciphering these dynamics is complicated by the fact that the ostensible jet response to the time-varying crossflow is a time-varying jet penetration. This drives the jet toward and away from the jet injection wall. These motions are perpendicular to the laser sheet and creates significant out-of-plane motions. The amplitude of crossflow unsteadiness appears to play a role in the sharpness of the wake dynamics. For the non-reacting cases, the wake dynamics are strong and dominant spectral features in the flowfield. For the reacting cases, the wake dynamics are spectrally distinct in the lower amplitude crossflow unsteadiness case, but a large unsteady amplitude crossflow appears to suppress the spectral bands in the frequency range corresponding to wake vortex dynamics.

Terahertz light-emitting graphene-channel transistor toward single-mode lasing

NASA Astrophysics Data System (ADS)

Yadav, Deepika; Tamamushi, Gen; Watanabe, Takayuki; Mitsushio, Junki; Tobah, Youssef; Sugawara, Kenta; Dubinov, Alexander A.; Satou, Akira; Ryzhii, Maxim; Ryzhii, Victor; Otsuji, Taiichi

2018-03-01

A distributed feedback dual-gate graphene-channel field-effect transistor (DFB-DG-GFET) was fabricated as a current-injection terahertz (THz) light-emitting laser transistor. We observed a broadband emission in a 1-7.6-THz range with a maximum radiation power of 10 μW as well as a single-mode emission at 5.2 THz with a radiation power of 0.1 μW both at 100 K when the carrier injection stays between the lower cutoff and upper cutoff threshold levels. The device also exhibited peculiar nonlinear threshold-like behavior with respect to the current-injection level. The LED-like broadband emission is interpreted as an amplified spontaneous THz emission being transcended to a single-mode lasing. Design constraints on waveguide structures for better THz photon field confinement with higher gain overlapping as well as DFB cavity structures with higher Q factors are also addressed towards intense, single-mode continuous wave THz lasing at room temperature.

Optical Microwave Interactions in Semiconductor Devices.

DTIC Science & Technology

1980-11-01

geometry can be used in microwave-optical analog T signal processing systems. A theoretical and experimental study of mode locking in (GaAI)As injection... STUDY OF MODE-LOCKING IN (GaAl)As INJECTION LASER .......... ......................... ... 55 A. Experimental Set-Up and DC Characteristics...modulation and 4 detection of optical beams at microwave frequencies. Our approach for modulating the optical beam has been to study the modulation capability

Top-up injection schemes for future circular lepton collider

NASA Astrophysics Data System (ADS)

Aiba, M.; Goddard, B.; Oide, K.; Papaphilippou, Y.; Saá Hernández, Á.; Shwartz, D.; White, S.; Zimmermann, F.

2018-02-01

Top-up injection is an essential ingredient for the future circular lepton collider (FCC-ee) to maximize the integrated luminosity and it determines the design performance. In ttbar operation mode, with a beam energy of 175 GeV, the design lifetime of ∼1 h is the shortest of the four anticipated operational modes, and the beam lifetime may be even shorter in actual operation. A highly robust top-up injection scheme is consequently imperative. Various top-up methods are investigated and a number of suitable schemes are considered in developing alternative designs for the injection straight section of the collider ring. For the first time, we consider multipole-kicker off-energy injection, for minimizing detector background in top-up operation, and the use of a thin wire septum in a lepton storage ring, for maximizing the luminosity.

Optically detected, single nanoparticle mass spectrometer with pre-filtered electrospray nanoparticle source

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

Howder, Collin R.; Bell, David M.; Anderson, Scott L.

2014-01-15

An instrument designed for non-destructive mass analysis of single trapped nanoparticles is described. The heart of the instrument is a 3D quadrupole (Paul) trap constructed to give optical access to the trap center along ten directions, allowing passage of lasers for particle heating and detection, particle injection, collection of scattered or fluorescent photons for particle detection and mass analysis, and collection of particles on TEM grids for analysis, as needed. Nanoparticles are injected using an electrospray ionization (ESI) source, and conditions are described for spraying and trapping polymer particles, bare metal particles, and ligand stabilized particles with masses ranging frommore » 200 kDa to >3 GDa. Conditions appropriate to ESI and injection of different types of particles are described. The instrument is equipped with two ion guides separating the ESI source and nanoparticle trap. The first ion guide is mostly to allow desolvation and differential pumping before the particles enter the trap section of the instrument. The second is a linear quadrupole guide, which can be operated in mass selective or mass band-pass modes to limit transmission to species with mass-to-charge ratios in the range of interest. With a little experience, the design allows injection of single particles into the trap upon demand.« less

Feedback effects in optical communication systems: characteristic curve for single-mode InGaAsP lasers.

PubMed

Brivio, F; Reverdito, C; Sacchi, G; Chiaretti, G; Milani, M

1992-08-20

An experimental analysis of InGaAsP injection lasers shows an unexpected decrease of the differential quantum efficiency as a function of injected current when optical power is fed back into the active cavity of a diode inserted into a long transmission line. To investigate the response of laser diodes to optical feedback, we base our analysis on a microscopic model, resulting in a set of coupled equations that include the microscopic parameters that characterize the material and the device. This description takes into account the nonlinear dependence of the interband carrier lifetime on the level of optical feedback. Good agreement between the analytical description and experimental data is obtained for threshold current and differential quantum efficiency as functions of the feedback ratio.

COLLECTIVE EFFECTS AT INJECTION FOR THE APS-U MBA LATTICE

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

Lindberg, R.; Borland, M.; Blednykh, A.

The Advanced Photon Source has proposed an upgrade to a multi-bend achromat (MBA) with a proposed timing mode calls for 48 bunches of 15 nC each. In this mode of operation we find that phase space mismatch from the booster can drive large wakefields that in turn may limit the current below that of the nominal collective instability threshold. We show that collective effects at injection lead to emittance growth that makes usual off-axis accumulation very challenging. On-axis injection ameliorates many of these issues, but we find that transverse feedback is still required. We explore the role of impedance, feedback,more » and phase-space mismatch on transverse instabilities at injection.« less

New steady-state quiescent high-confinement plasma in an experimental advanced superconducting tokamak.

PubMed

Hu, J S; Sun, Z; Guo, H Y; Li, J G; Wan, B N; Wang, H Q; Ding, S Y; Xu, G S; Liang, Y F; Mansfield, D K; Maingi, R; Zou, X L; Wang, L; Ren, J; Zuo, G Z; Zhang, L; Duan, Y M; Shi, T H; Hu, L Q

2015-02-06

A critical challenge facing the basic long-pulse high-confinement operation scenario (H mode) for ITER is to control a magnetohydrodynamic (MHD) instability, known as the edge localized mode (ELM), which leads to cyclical high peak heat and particle fluxes at the plasma facing components. A breakthrough is made in the Experimental Advanced Superconducting Tokamak in achieving a new steady-state H mode without the presence of ELMs for a duration exceeding hundreds of energy confinement times, by using a novel technique of continuous real-time injection of a lithium (Li) aerosol into the edge plasma. The steady-state ELM-free H mode is accompanied by a strong edge coherent MHD mode (ECM) at a frequency of 35-40 kHz with a poloidal wavelength of 10.2 cm in the ion diamagnetic drift direction, providing continuous heat and particle exhaust, thus preventing the transient heat deposition on plasma facing components and impurity accumulation in the confined plasma. It is truly remarkable that Li injection appears to promote the growth of the ECM, owing to the increase in Li concentration and hence collisionality at the edge, as predicted by GYRO simulations. This new steady-state ELM-free H-mode regime, enabled by real-time Li injection, may open a new avenue for next-step fusion development.

Flow Injection Mass Spectral Fingerprints Demonstrate Chemical Differences in Rio Red Grapefruit with Respect to Year, Harvest Time, and Conventional versus Organic Farming

PubMed Central

Chen, Pei; Harnly, James M.; Lester, Gene E.

2013-01-01

Spectral fingerprints were acquired for Rio Red grapefruit using flow injection electrospray ionization with ion trap and time-of-flight mass spectrometry (FI-ESI-IT-MS and FI-ESI-TOF-MS). Rio Red grapefruits were harvested 3 times a year (early, mid, and late harvests) in 2005 and 2006 from conventionally and organically grown trees. Data analysis using analysis of variance principal component analysis (ANOVA-PCA) demonstrated that, for both MS systems, the chemical patterns were different as a function of farming mode (conventional vs organic), as well as growing year and time of harvest. This was visually obvious with PCA and was shown to be statistically significant using ANOVA. The spectral fingerprints provided a more inclusive view of the chemical composition of the grapefruit and extended previous conclusions regarding the chemical differences between conventionally and organically grown Rio Red grapefruit. PMID:20337420

ELM mitigation with pellet ELM triggering and implications for PFCs and plasma performance in ITER

DOE PAGES

Baylor, Larry R.; Lang, P. T.; Allen, Steve L.; ...

2014-10-05

The triggering of rapid small edge localized modes (ELMs) by high frequency pellet injection has been proposed as a method to prevent large naturally occurring ELMs that can erode the ITER plasma facing components. Deuterium pellet injection has been used to successfully demonstrate the on-demand triggering of edge localized modes (ELMs) at much higher rates and with much smaller intensity than natural ELMs. The proposed hypothesis for the triggering mechanism of ELMs by pellets is the local pressure perturbation resulting from reheating of the pellet cloud that can exceed the local high-n ballooning mode threshold where the pellet is injected.more » Nonlinear MHD simulations of the pellet ELM triggering show destabilization of high-n ballooning modes by such a local pressure perturbation. A review of the recent pellet ELM triggering results from ASDEX Upgrade (AUG), DIII-D, and JET reveals that a number of uncertainties about this ELM mitigation technique still remain. These include the heat flux impact pattern on the divertor and wall from pellet triggered and natural ELMs, the necessary pellet size and injection location to reliably trigger ELMs, and the level of fueling to be expected from ELM triggering pellets and synergy with larger fueling pellets. The implications of these issues for pellet ELM mitigation in ITER and its impact on the PFCs are presented along with the design features of the pellet injection system for ITER.« less

ELM mitigation with pellet ELM triggering and implications for PFCs and plasma performance in ITER

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

Baylor, Larry R.; Lang, P.; Allen, S. L.

2015-08-01

The triggering of rapid small edge localized modes (ELMs) by high frequency pellet injection has been proposed as a method to prevent large naturally occurring ELMs that can erode the ITER plasma facing components (PFCs). Deuterium pellet injection has been used to successfully demonstrate the on-demand triggering of edge localized modes (ELMs) at much higher rates and with much smaller intensity than natural ELMs. The proposed hypothesis for the triggering mechanism of ELMs by pellets is the local pressure perturbation resulting from reheating of the pellet cloud that can exceed the local high-n ballooning mode threshold where the pellet ismore » injected. Nonlinear MHD simulations of the pellet ELM triggering show destabilization of high-n ballooning modes by such a local pressure perturbation.A review of the recent pellet ELM triggering results from ASDEX Upgrade (AUG), DIII-D, and JET reveals that a number of uncertainties about this ELM mitigation technique still remain. These include the heat flux impact pattern on the divertor and wall from pellet triggered and natural ELMs, the necessary pellet size and injection location to reliably trigger ELMs, and the level of fueling to be expected from ELM triggering pellets and synergy with larger fueling pellets. The implications of these issues for pellet ELM mitigation in ITER and its impact on the PFCs are presented along with the design features of the pellet injection system for ITER.« less

Generating a stationary infinite range tractor force via a multimode optical fibre

NASA Astrophysics Data System (ADS)

Ebongue, C. A.; Holzmann, D.; Ostermann, S.; Ritsch, H.

2017-06-01

Optical fibres confine and guide light almost unattenuated and thus convey light forces to polarizable nano-particles over very long distances. Radiation pressure forces arise from scattering of guided photons into free space while gradient forces are based on coherent scattering between different fibre modes or propagation directions. Interestingly, even scattering between co-propagating modes induces longitudinal forces as the transverse confinement of the light modes creates mode dependent longitudinal wave-vectors and photon momenta. We generalize a proven scattering matrix based approach to calculate single as well as inter-particle forces to include several forward and backward propagating modes. We show that an injection of the higher order mode only in a two mode fibre will induce a stationary tractor force against the injection direction, when the mode coupling to the lower order mode dominates against backscattering and free space losses. Generically this arises for non-absorbing particles at the centre of a waveguide. The model also gives improved predictions for inter-particle forces in evanescent nanofibre fields as experimentally observed recently. Surprisingly strong tractor forces can also act on whole optically bound arrays.

Pellet injection into H-mode ITER plasma with the presence of internal transport barriers

NASA Astrophysics Data System (ADS)

Leekhaphan, P.; Onjun, T.

2011-04-01

The impacts of pellet injection into ITER type-1 ELMy H-mode plasma with the presence of internal transport barriers (ITBs) are investigated using self-consistent core-edge simulations of 1.5D BALDUR integrated predictive modeling code. In these simulations, the plasma core transport is predicted using a combination of a semi-empirical Mixed B/gB anomalous transport model, which can self-consistently predict the formation of ITBs, and the NCLASS neoclassical model. For simplicity, it is assumed that toroidal velocity for ω E× B calculation is proportional to local ion temperature. In addition, the boundary conditions are predicted using the pedestal temperature model based on magnetic and flow shear stabilization width scaling; while the density of each plasma species, including both hydrogenic and impurity species, at the boundary are assumed to be a large fraction of its line averaged density. For the pellet's behaviors in the hot plasma, the Neutral Gas Shielding (NGS) model by Milora-Foster is used. It was found that the injection of pellet could result in further improvement of fusion performance from that of the formation of ITB. However, the impact of pellet injection is quite complicated. It is also found that the pellets cannot penetrate into a deep core of the plasma. The injection of the pellet results in a formation of density peak in the region close to the plasma edge. The injection of pellet can result in an improved nuclear fusion performance depending on the properties of pellet (i.e., increase up to 5% with a speed of 1 km/s and radius of 2 mm). A sensitivity analysis is carried out to determine the impact of pellet parameters, which are: the pellet radius, the pellet velocity, and the frequency of injection. The increase in the pellet radius and frequency were found to greatly improve the performance and effectiveness of fuelling. However, changing the velocity is observed to exert small impact.

Theoretical study on phase-locking of a radial array CO2 laser

NASA Astrophysics Data System (ADS)

Xu, Yonggen

2014-11-01

The phase-locking of the radial array CO2 laser (RAL) is introduced based on the injection-locking principle. The characteristic parameters of laser beams used in the phase-locking are described, and the coupling coefficient c00 between the injected mode and the eigenmode of RAL is calculated. The laser modes from RAL are the low-order Hermite Gaussian modes due to the diffraction loss. The analytical formula for the output beam through an ABCD optical system is derived according Collins formula. The numerical examples are given to illustrate our analytical results.

System and process for pulsed multiple reaction monitoring

DOEpatents

Belov, Mikhail E

2013-05-17

A new pulsed multiple reaction monitoring process and system are disclosed that uses a pulsed ion injection mode for use in conjunction with triple-quadrupole instruments. The pulsed injection mode approach reduces background ion noise at the detector, increases amplitude of the ion signal, and includes a unity duty cycle that provides a significant sensitivity increase for reliable quantitation of proteins/peptides present at attomole levels in highly complex biological mixtures.

Tunable single frequency fiber laser based on FP-LD injection locking.

PubMed

Zhang, Aiqin; Feng, Xinhuan; Wan, Minggui; Li, Zhaohui; Guan, Bai-ou

2013-05-20

We propose and demonstrate a tunable single frequency fiber laser based on Fabry Pérot laser diode (FP-LD) injection locking. The single frequency operation principle is based on the fact that the output from a FP-LD injection locked by a multi-longitudinal-mode (MLM) light can have fewer longitudinal-modes number and narrower linewidth. By inserting a FP-LD in a fiber ring laser cavity, single frequency operation can be possibly achieved when stable laser oscillation established after many roundtrips through the FP-LD. Wavelength switchable single frequency lasing can be achieved by adjusting the tunable optical filter (TOF) in the cavity to coincide with different mode of the FP-LD. By adjustment of the drive current of the FP-LD, the lasing modes would shift and wavelength tunable operation can be obtained. In experiment, a wavelength tunable range of 32.4 nm has been obtained by adjustment of the drive current of the FP-LD and a tunable filter in the ring cavity. Each wavelength has a side-mode suppression ratio (SMSR) of at least 41 dB and a linewidth of about 13 kHz.

Disruption avoidance by means of electron cyclotron waves

NASA Astrophysics Data System (ADS)

Esposito, B.; Granucci, G.; Maraschek, M.; Nowak, S.; Lazzaro, E.; Giannone, L.; Gude, A.; Igochine, V.; McDermott, R.; Poli, E.; Reich, M.; Sommer, F.; Stober, J.; Suttrop, W.; Treutterer, W.; Zohm, H.; ASDEX Upgrade, the; FTU Teams

2011-12-01

Disruptions are very challenging to ITER operation as they may cause damage to plasma facing components due to direct plasma heating, forces on structural components due to halo and eddy currents and the production of runaway electrons. Electron cyclotron (EC) waves have been demonstrated as a tool for disruption avoidance by a large set of recent experiments performed in ASDEX Upgrade and FTU using various disruption types, plasma operating scenarios and power deposition locations. The technique is based on the stabilization of magnetohydrodynamic (MHD) modes (mainly m/n = 2/1) through the localized injection of EC power on the resonant surface. This paper presents new results obtained in ASDEX Upgrade regarding stable operation above the Greenwald density achieved after avoidance of density limit disruptions by means of ECRH and suitable density feedback control (L-mode ohmic plasmas, Ip = 0.6 MA, Bt = 2.5 T) and NTM-driven disruptions at high-β limit delayed/avoided by means of both co-current drive (co-ECCD) and pure heating (ECRH) with power <=1.7 MW (H-mode NBI-heated plasmas, PNBI ~ 7.5 MW, Ip = 1 MA, Bt = 2.1 T, q95 ~ 3.6). The localized perpendicular injection of ECRH/ECCD onto a resonant surface leads to the delay and/or complete avoidance of disruptions. The experiments indicate the existence of a power threshold for mode stabilization to occur. An analysis of the MHD mode evolution using the generalized Rutherford equation coupled to the frequency and phase evolution equations shows that control of the modes is due to EC heating close to the resonant surface. The ECRH contribution (Δ'H term) is larger than the co-ECCD one in the initial and more important phase when the discharge is 'saved'. Future research and developments of the disruption avoidance technique are also discussed.

Applying short-duration pulses as a mean to enhance volatile organic compounds removal by air sparging.

PubMed

Ben Neriah, Asaf; Paster, Amir

2017-10-01

Application of short-duration pulses of high air pressure, to an air sparging system for groundwater remediation, was tested in a two-dimensional laboratory setup. It was hypothesized that this injection mode, termed boxcar, can enhance the remediation efficiency due to the larger ZOI and enhanced mixing which results from the pressure pulses. To test this hypothesis, flow and transport experiments were performed. Results confirm that cyclically applying short-duration pressure pulses may enhance contaminant cleanup. Comparing the boxcar to conventional continuous air-injection shows up to a three-fold increase in the single well radius of influence, dependent on the intensity of the short-duration pressure-pulses. The cleanup efficiency of Toluene from the water was 95% higher than that achieved under continuous injection with the same average conditions. This improvement was attributed to the larger zone of influence and higher average air permeability achieved in the boxcar mode, relative to continuous sparging. Mixing enhancement resultant from recurring pressure pulses was suggested as one of the mechanisms which enhance the contaminant cleanup. The application of a boxcar mode in an existing, multiwell, air sparging setup can be relatively straightforward: it requires the installation of an on-off valve in each of the injection-wells and a central control system. Then, turning off some of the wells, for a short-duration, result in a stepwise increase in injection pressure in the rest of the wells. It is hoped that this work will stimulate the additional required research and ultimately a field scale application of this new injection mode. Copyright © 2017 Elsevier B.V. All rights reserved.

Remote beating of parallel or orthogonally polarized dual-wavelength optical carriers for 5G millimeter-wave radio-over-fiber link.

PubMed

Wang, Huai-Yung; Chi, Yu-Chieh; Lin, Gong-Ru

2016-08-08

A novel millimeter-wave radio over fiber (MMW-RoF) link at carrier frequency of 35-GHz is proposed with the use of remotely beating MMW generation from reference master and injected slave colorless laser diode (LD) carriers at orthogonally polarized dual-wavelength injection-locking. The slave colorless LD supports lasing one of the dual-wavelength master modes with orthogonal polarizations, which facilitates the single-mode direct modulation of the quadrature amplitude modulation (QAM) orthogonal frequency division multiplexing (OFDM) data. Such an injected single-carrier encoding and coupled dual-carrier transmission with orthogonal polarization effectively suppresses the cross-heterodyne mode-beating intensity noise, the nonlinear modulation (NLM) and four-wave mixing (FWM) sidemodes during injection locking and fiber transmission. In 25-km single-mode fiber (SMF) based wireline system, the dual-carrier under single-mode encoding provides baseband 24-Gbit/s 64-QAM OFDM transmission with an error vector magnitude (EVM) of 8.8%, a bit error rate (BER) of 3.7 × 10^-3, a power penalty of <1.5 dB. After remotely self-beating for wireless transmission, the beat MMW carrier at 35 GHz can deliver the passband 16-QAM OFDM at 4 Gbit/s to show corresponding EVM and BER of 15.5% and 1.4 × 10^-3, respectively, after 25-km SMF and 1.6-m free-space transmission.

Optical-microwave interactions in semiconductor devices

NASA Astrophysics Data System (ADS)

Figueroa, L.; Slayman, C. W.; Yen, H. W.

1981-03-01

The results of an extensive characterization of microwave-optical devices is presented. The study has concentrated in the optical injection locking of IMPATT oscillators, high-speed analog modulation of (GaAl)As injection laser, mode-locking of (GaAl)As injection laser, and high-speed optical detectors.

Effects of biodiesel on emissions of a bus diesel engine.

PubMed

Kegl, Breda

2008-03-01

This paper discusses the influence of biodiesel on the injection, spray, and engine characteristics with the aim to reduce harmful emissions. The considered engine is a bus diesel engine with injection M system. The injection, fuel spray, and engine characteristics, obtained with biodiesel, are compared to those obtained with mineral diesel (D2) under various operating regimes. The considered fuel is neat biodiesel from rapeseed oil. Its density, viscosity, surface tension, and sound velocity are determined experimentally and compared to those of D2. The obtained results are used to analyze the most important injection, fuel spray, and engine characteristics. The injection characteristics are determined numerically under the operating regimes, corresponding to the 13 mode ESC test. The fuel spray is obtained experimentally under peak torque condition. Engine characteristics are determined experimentally under 13 mode ESC test conditions. The results indicate that, by using biodiesel, harmful emissions (NO(x), CO, smoke and HC) can be reduced to some extent by adjusting the injection pump timing properly.

Photonic jet: key role of injection for etchings with a shaped optical fiber tip.

PubMed

Pierron, Robin; Zelgowski, Julien; Pfeiffer, Pierre; Fontaine, Joël; Lecler, Sylvain

2017-07-15

We demonstrate the key role of the laser injection into a multimode fiber to obtain a photonic jet (PJ). PJ, a high concentrated propagating beam with a full width at half-maximum smaller than the diffraction limit, is here generated with a shaped optical fiber tip using a pulsed laser source (1064 nm, 100 ns, 35 kHz). Three optical injection systems of light are compared. For similar etched marks on silicon with diameters around 1 μm, we show that the required ablation energy is minimum when the injected light beam is close to the fundamental mode diameter of the fiber. Thus, we confirm experimentally that to obtain a PJ out of an optical fiber, light injection plays a role as important as that of the tip shape and, therefore, the role of the fundamental mode in the process.

Selection and amplification of a single optical frequency comb mode for laser cooling of the strontium atoms in an optical clock

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

Liu, Hui; School of Physics, University of Chinese Academy of Sciences, Beijing 100049; Yin, Mojuan

2015-10-12

In this paper, we report on the active filtering and amplification of a single mode from an optical femtosecond laser comb with mode spacing of 250 MHz by optical injection of two external-cavity diode lasers operating in cascade to build a narrow linewidth laser for laser cooling of the strontium atoms in an optical lattice clock. Despite the low injection of individual comb mode of approximately 50 nW, a single comb line at 689 nm could be filtered and amplified to reach as high as 10 mW with 37 dB side mode suppression and a linewidth of 240 Hz. This method could be appliedmore » over a broad spectral band to build narrow linewidth lasers for various applications.« less

Tunable single-longitudinal-mode operation of an injection-locked TEA CO2 laser. [ozone absorption spectroscopy

NASA Technical Reports Server (NTRS)

Megie, G.; Menzies, R. T.

1979-01-01

The tunable single-longitudinal-mode operation of a TEA CO2 laser by an injection technique using a CW waveguide laser as the master oscillator is reported. With the experimental arrangement described, in which the waveguide laser frequency is tuned to correspond to one of the oscillating longitudinal modes of the TEA laser, single-longitudinal-mode operation was achieved with no apparent reduction in the TEA output energy, on various CO2 lines with frequency offsets from the line center as large as 300 MHz. The capability of this technique for high-resolution spectroscopy or atmospheric lidar studies is demonstrated by the recording of the absorption spectrum of a strong ozone line.

Study on the characteristic and application of DFB semiconductor lasers under optical injection for microwave photonics

NASA Astrophysics Data System (ADS)

Pu, Tao; Wang, Wei wei

2018-01-01

In order to apply optical injection effect in Microwave Photonics system, The red-shift effect of the cavity mode of the DFB semiconductor laser under single-frequency optical injection is studied experimentally, and the red-shift curve of the cavity mode is measured. The wavelength-selective amplification property of the DFB semiconductor laser under multi-frequency optical injection is also investigated, and the gain curves for the injected signals in different injection ratios are measured in the experiment. A novel and simple structure to implement a single-passband MPF with wideband tunability based on the wavelength-selective amplification of a DFB semiconductor laser under optical injection is proposed and experimentally demonstrated. MPFs with center frequency tuned from 13 to 41 GHz are realized in the experiment. A wideband and frequency-tunable optoelectronic oscillator based on a directly modulated distributed feedback (DFB) semiconductor laser under optical injection is proposed and experimentally demonstrated. By optical injection, the relaxation oscillation frequency of the DFB laser is enhanced and its high modulation efficiency makes the loop oscillate without the necessary of the electrical filter. An experiment is performed; microwave signals with frequency tuned from 5.98 to 15.22 GHz are generated by adjusting the injection ratio and frequency detuning between the master and slave lasers.

Stable Spheromaks Sustained by Neutral Beam Injection

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

Fowler, T K; Jayakumar, R; McLean, H S

It is shown that spheromak equilibria, stable at zero-beta but departing from the Taylor state, could be sustained by non-inductive current drive at acceptable power levels. Stability to both ideal MHD and tearing modes is verified using the NIMROD code for linear stability analysis. Non-linear NIMROD calculations with non-inductive current drive and pressure effects could point the way to improved fusion reactors.

Overview of results from the MST reversed field pinch experiment

NASA Astrophysics Data System (ADS)

Sarff, J. S.; Almagri, A. F.; Anderson, J. K.; Borchardt, M.; Carmody, D.; Caspary, K.; Chapman, B. E.; Den Hartog, D. J.; Duff, J.; Eilerman, S.; Falkowski, A.; Forest, C. B.; Goetz, J. A.; Holly, D. J.; Kim, J.-H.; King, J.; Ko, J.; Koliner, J.; Kumar, S.; Lee, J. D.; Liu, D.; Magee, R.; McCollam, K. J.; McGarry, M.; Mirnov, V. V.; Nornberg, M. D.; Nonn, P. D.; Oliva, S. P.; Parke, E.; Reusch, J. A.; Sauppe, J. P.; Seltzman, A.; Sovinec, C. R.; Stephens, H.; Stone, D.; Theucks, D.; Thomas, M.; Triana, J.; Terry, P. W.; Waksman, J.; Bergerson, W. F.; Brower, D. L.; Ding, W. X.; Lin, L.; Demers, D. R.; Fimognari, P.; Titus, J.; Auriemma, F.; Cappello, S.; Franz, P.; Innocente, P.; Lorenzini, R.; Martines, E.; Momo, B.; Piovesan, P.; Puiatti, M.; Spolaore, M.; Terranova, D.; Zanca, P.; Belykh, V.; Davydenko, V. I.; Deichuli, P.; Ivanov, A. A.; Polosatkin, S.; Stupishin, N. V.; Spong, D.; Craig, D.; Harvey, R. W.; Cianciosa, M.; Hanson, J. D.

2013-10-01

An overview of recent results from the MST programme on physics important for the advancement of the reversed field pinch (RFP) as well as for improved understanding of toroidal magnetic confinement more generally is reported. Evidence for the classical confinement of ions in the RFP is provided by analysis of impurity ions and energetic ions created by 1 MW neutral beam injection (NBI). The first appearance of energetic-particle-driven modes by NBI in a RFP plasma is described. MST plasmas robustly access the quasi-single-helicity state that has commonalities to the stellarator and ‘snake’ formation in tokamaks. In MST the dominant mode grows to 8% of the axisymmetric field strength, while the remaining modes are reduced. Predictive capability for tearing mode behaviour has been improved through nonlinear, 3D, resistive magnetohydrodynamic computation using the measured resistivity profile and Lundquist number, which reproduces the sawtooth cycle dynamics. Experimental evidence and computational analysis indicates two-fluid effects, e.g., Hall physics and gyro-viscosity, are needed to understand the coupling of parallel momentum transport and current profile relaxation. Large Reynolds and Maxwell stresses, plus separately measured kinetic stress, indicate an intricate momentum balance and a possible origin for MST's intrinsic plasma rotation. Gyrokinetic analysis indicates that micro-tearing modes can be unstable at high beta, with a critical gradient for the electron temperature that is larger than for tokamak plasmas by roughly the aspect ratio.

Photonic lantern adaptive spatial mode control in LMA fiber amplifiers.

PubMed

Montoya, Juan; Aleshire, Chris; Hwang, Christopher; Fontaine, Nicolas K; Velázquez-Benítez, Amado; Martz, Dale H; Fan, T Y; Ripin, Dan

2016-02-22

We demonstrate adaptive-spatial mode control (ASMC) in few-moded double-clad large mode area (LMA) fiber amplifiers by using an all-fiber-based photonic lantern. Three single-mode fiber inputs are used to adaptively inject the appropriate superposition of input modes in a multimode gain fiber to achieve the desired mode at the output. By actively adjusting the relative phase of the single-mode inputs, near-unity coherent combination resulting in a single fundamental mode at the output is achieved.

Phase-locking of annular-combination CO2 laser

NASA Astrophysics Data System (ADS)

Qi, Tingxiang; Chen, Mei; Zhang, Rongzhu; Xiao, Qianyi

2015-07-01

A new annular-combination resonator structure adopting the external-injection phase-locking technology is presented theoretically for that the beam quality of stable annular resonator is not satisfying. The phase-locking principle and feasibility are characterized by energy density of injection beam and coupling coefficient. Based on the diffraction theory, output mode of the resonator with phase-locking is deduced and simulated. Results also confirm that injection beam have a good control effect on output mode. The intensity distributions of output beam are studied briefly and indicate that this new resonator which is adaptable to annular gain media can produce high-power laser beam with high quality.

Radiation from a space charge dominated linear electron beam

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

Biswas, Debabrata

2008-01-15

It is commonly known that radiation loss in linear beam transport is largely unimportant. For a space charge dominated linear beam, however, radiation power loss can be an appreciable fraction of the injected beam power [Biswas, Kumar, and Puri, Phys. Plasmas 14, 094702 (2007)]. Exploring this further, the electromagnetic nature of radiation due to the passage of a space charge dominated electron beam in a 'closed' drift tube is explicitly demonstrated by identifying the cavity modes where none existed prior to beam injection. It is further shown that even in an 'open' drift tube from which radiation may leak, themore » modes that escape contribute to the time variation of the electric and magnetic fields in the transient phase. As the window opening increases, the oscillatory transient phase disappears altogether. However, the 'bouncing ball' modes survive and can be observed between the injection and collection plates.« less

Microwave experiments on Prairie View Rotamak

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

Zhou, R. J.; Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031; Xu, M.

2015-05-15

A 6 kW/2.45 GHz microwave system has been added on Prairie View Rotamak, and a series of experiments with microwave heating in both O-mode and X-mode configurations have been performed. Effective ionization of hydrogen in the two configurations is observed when filling pressure of the hydrogen gas is under p{sub f}=0.1 Pa. Clear oscillations in plasma current I{sub p} and magnetic field B{sub R} are excited when microwaves are injected into plasma in the X-mode configuration. The higher the injected microwave power, the sooner the emergence of the magnetic oscillations in B{sub R}, which implies the microwave may have decreased the elongationmore » of the plasma. In the experiments, the efficiency of the current drive mechanism due to the injected microwave is about 0.2 kA/kW.« less

Dynamic mode decomposition for plasma diagnostics and validation.

PubMed

Taylor, Roy; Kutz, J Nathan; Morgan, Kyle; Nelson, Brian A

2018-05-01

We demonstrate the application of the Dynamic Mode Decomposition (DMD) for the diagnostic analysis of the nonlinear dynamics of a magnetized plasma in resistive magnetohydrodynamics. The DMD method is an ideal spatio-temporal matrix decomposition that correlates spatial features of computational or experimental data while simultaneously associating the spatial activity with periodic temporal behavior. DMD can produce low-rank, reduced order surrogate models that can be used to reconstruct the state of the system with high fidelity. This allows for a reduction in the computational cost and, at the same time, accurate approximations of the problem, even if the data are sparsely sampled. We demonstrate the use of the method on both numerical and experimental data, showing that it is a successful mathematical architecture for characterizing the helicity injected torus with steady inductive (HIT-SI) magnetohydrodynamics. Importantly, the DMD produces interpretable, dominant mode structures, including a stationary mode consistent with our understanding of a HIT-SI spheromak accompanied by a pair of injector-driven modes. In combination, the 3-mode DMD model produces excellent dynamic reconstructions across the domain of analyzed data.

Dynamic mode decomposition for plasma diagnostics and validation

NASA Astrophysics Data System (ADS)

Taylor, Roy; Kutz, J. Nathan; Morgan, Kyle; Nelson, Brian A.

2018-05-01

We demonstrate the application of the Dynamic Mode Decomposition (DMD) for the diagnostic analysis of the nonlinear dynamics of a magnetized plasma in resistive magnetohydrodynamics. The DMD method is an ideal spatio-temporal matrix decomposition that correlates spatial features of computational or experimental data while simultaneously associating the spatial activity with periodic temporal behavior. DMD can produce low-rank, reduced order surrogate models that can be used to reconstruct the state of the system with high fidelity. This allows for a reduction in the computational cost and, at the same time, accurate approximations of the problem, even if the data are sparsely sampled. We demonstrate the use of the method on both numerical and experimental data, showing that it is a successful mathematical architecture for characterizing the helicity injected torus with steady inductive (HIT-SI) magnetohydrodynamics. Importantly, the DMD produces interpretable, dominant mode structures, including a stationary mode consistent with our understanding of a HIT-SI spheromak accompanied by a pair of injector-driven modes. In combination, the 3-mode DMD model produces excellent dynamic reconstructions across the domain of analyzed data.

Control of Current Profile and Instability by Radiofrequency Wave Injection in JT-60U and Its Applicability in JT-60SA

NASA Astrophysics Data System (ADS)

Isayama, A.; Suzuki, T.; Hayashi, N.; Ide, S.; Hamamatsu, K.; Fujita, T.; Hosoyama, H.; Kamada, Y.; Nagasaki, K.; Oyama, N.; Ozeki, T.; Sakata, S.; Seki, M.; Sueoka, M.; Takechi, M.; Urano, H.

2007-09-01

Recent results of control of current profile and instability using radiofrequency wave in JT-60U and prediction analysis in JT-60SA are descried. In JT-60U, control of current profile in high-beta regime was demonstrated by using a real-time system, where the motional Stark effect diagnostic and lower hybrid wave were used as a detector and actuator, respectively. The minimum value of the safety factor was raised from 1.3 to 1.7 so as to follow the commanded value. Complete stabilization of a neoclassical tearing mode (NTM) with the poloidal mode number m = 2 and the toroidal mode number n = 1 was demonstrated using electron cyclotron (EC) current drive. By scanning the location of EC current drive in detail, strong stabilization effect was found for misalignment less than about half of the full island width. In addition, destabilization of the 2/1 NTM was observed for misalignment comparable to the full island width. Simulation of NTM stabilization in JT-60SA was performed by using the TOPICS code combined with the modified Rutherford equation. The TOPICS simulation showed that complete stabilization can be achieved more effectively by optimizing the EC wave injection angle and modulating the EC wave.

Control of Current Profile and Instability by Radiofrequency Wave Injection in JT-60U and Its Applicability in JT-60SA

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

Isayama, A.; Suzuki, T.; Hayashi, N.

2007-09-28

Recent results of control of current profile and instability using radiofrequency wave in JT-60U and prediction analysis in JT-60SA are descried. In JT-60U, control of current profile in high-beta regime was demonstrated by using a real-time system, where the motional Stark effect diagnostic and lower hybrid wave were used as a detector and actuator, respectively. The minimum value of the safety factor was raised from 1.3 to 1.7 so as to follow the commanded value. Complete stabilization of a neoclassical tearing mode (NTM) with the poloidal mode number m = 2 and the toroidal mode number n = 1 wasmore » demonstrated using electron cyclotron (EC) current drive. By scanning the location of EC current drive in detail, strong stabilization effect was found for misalignment less than about half of the full island width. In addition, destabilization of the 2/1 NTM was observed for misalignment comparable to the full island width. Simulation of NTM stabilization in JT-60SA was performed by using the TOPICS code combined with the modified Rutherford equation. The TOPICS simulation showed that complete stabilization can be achieved more effectively by optimizing the EC wave injection angle and modulating the EC wave.« less

Reduction of ELM Intensity on DIII-D by On-demand Triggering With High Frequency Pellet Injection and Implications for ITER

NASA Astrophysics Data System (ADS)

Baylor, L. R.

2012-10-01

Deuterium pellet injection was used on the DIII-D tokamak to successfully demonstrate for the first time the on-demand triggering of ELMs at a 10x higher rate, and with much smaller intensity, than natural edge localized modes (ELMs). The triggering of small ELMs by high frequency pellet injection has been proposed as a method to prevent large ELMs that can erode the ITER plasma facing components [1]. The demonstration was made by injecting slow (<200 m/s) 1.3 mm diameter deuterium pellets at 60 Hz from the low field side in an ITER similar plasma with 5 Hz natural ELM frequency. The input power was only slightly above the H-mode threshold. Similar non-pellet discharges had ELM energy losses up to 55 kJ (˜8% of total stored energy), while the case with pellets demonstrated ELMs with an average energy loss less than 3 kJ (<1% of the total). Total divertor ELM heat flux was reduced by more than a factor of 10. Central accumulation of Ni was significantly reduced in the pellet triggered ELM case. No significant increase in density or decrease in energy confinement was observed. Stability analysis of these discharges shows that the pedestal parameters are approaching the peeling unstable region just before a natural ELM crash. In the rapid pellet small ELM case, the pedestal conditions are well within the stable region with a narrower pedestal width observed. This narrower width is consistent with a picture in which the pellets are triggering the ELMs before the width expands to the critical ELM width. Nonlinear MHD simulations of the pellet ELM triggering show destabilization of ballooning modes by a local pressure perturbation. The implications of these results for pellet ELM pacing in ITER will be discussed. 6pt [1] P.T. Lang et al., Nucl. Fusion 44, 665 (2004).

The cardiovascular effects of a chimeric opioid peptide based on morphiceptin and PFRTic-NH2.

PubMed

Li, Meixing; Zhou, Lanxia; Ma, Guoning; Cao, Shuo; Dong, Shouliang

2013-01-01

MCRT (YPFPFRTic-NH(2)) is a chimeric opioid peptide based on morphiceptin and PFRTic-NH(2). In order to assess the cardiovascular effect of MCRT, it was administered by intravenous (i.v.) injection targeting at the peripheral nervous system and by intracerebroventricular (i.c.v.) injection targeting at the central nervous system. Naloxone and L-NAME were injected before MCRT to investigate possible interactions with MCRT. Results show that administration of MCRT by i.v. or i.c.v. injection could induce bradycardia and decrease in mean arterial pressure (MAP) at a greater degree than that with morphiceptin and PFRTic-NH(2). When MCRT and NPFF were coinjected, we observed a dose-dependent weakening of these cardiovascular effects by MCRT. Because naloxone completely abolished the cardiovascular effects of MCRT, we conclude that opioid receptors are involved in regulating the MAP of MCRT regardless of modes of injection. The effect of MCRT on heart rate is completely dependent on opioid receptors when MCRT was administered by i.c.v. instead of i.v. The central nitric oxide (NO) pathway is involved in regulating blood pressure by MCRT under both modes of injection, but the peripheral NO pathway had no effect on lowering blood pressure mediated by MCRT when it was administered by i.c.v. Based on the results from different modes of injection, the regulation of heart rate by MCRT mainly involves in the central NO pathway. Lastly, we observed that the cardiovascular effects of MCRT such as bradycardia and decrease of blood pressure, were stronger than that of its parent peptides. Opioid receptors and the NO pathway are involved in the cardiovascular regulation by MCRT, and their degree of involvement differs between intravenous and intracerebroventricular injection. Copyright © 2012 Elsevier Inc. All rights reserved.

Injection-controlled laser resonator

DOEpatents

Chang, J.J.

1995-07-18

A new injection-controlled laser resonator incorporates self-filtering and self-imaging characteristics with an efficient injection scheme. A low-divergence laser signal is injected into the resonator, which enables the injection signal to be converted to the desired resonator modes before the main laser pulse starts. This injection technique and resonator design enable the laser cavity to improve the quality of the injection signal through self-filtering before the main laser pulse starts. The self-imaging property of the present resonator reduces the cavity induced diffraction effects and, in turn, improves the laser beam quality. 5 figs.

Injection-controlled laser resonator

DOEpatents

Chang, Jim J.

1995-07-18

A new injection-controlled laser resonator incorporates self-filtering and self-imaging characteristics with an efficient injection scheme. A low-divergence laser signal is injected into the resonator, which enables the injection signal to be converted to the desired resonator modes before the main laser pulse starts. This injection technique and resonator design enable the laser cavity to improve the quality of the injection signal through self-filtering before the main laser pulse starts. The self-imaging property of the present resonator reduces the cavity induced diffraction effects and, in turn, improves the laser beam quality.

Frequency stabilization and transverse mode discrimination in injection-seeded unstable resonator TEA CO2 lasers

NASA Technical Reports Server (NTRS)

Ancellet, G. M.; Menzies, R. T.; Brothers, A. M.

1987-01-01

Longitudinal mode selection by injection has been demonstrated as a viable technique for TEA-CO2 lasers with pulse energies of a Joule or greater. Once reliable generation of single-longitudinal-mode (SLM) pulses is obtained, the characteristics and the causes of intrapulse frequency variation can be studied. These include the effect of the decaying plasma, the thermal gradient due to the energy dissipation associated with the laser mechanism itself, and the pressure shift of the center frequency of the laser transition. The use of the positive-branch unstable resonator as an efficient means of coupling a discharge with large spatial dimensions to an optical cavity mode introduces another concern: namely, what can be done to emphasize transverse mode discrimination in an unstable resonator cavity while maintaining high coupling efficiency. These issues are discussed in this paper, and relevant experimental results are included.

Development of enantioselective chemiluminescence flow- and sequential-injection immunoassays for alpha-amino acids.

PubMed

Silvaieh, Hossein; Schmid, Martin G; Hofstetter, Oliver; Schurig, Volker; Gübitz, Gerald

2002-01-01

The development of an enantioselective flow-through chemiluminescence immunosensor for amino acids is described. The approach is based on a competitive assay using enantioselective antibodies. Two different instrumental approaches, a flow-injection (FIA) and a sequential-injection system (SIA), are used. Compared to the flow-injection technique, the sequential injection-mode showed better repeatability. Both systems use an immunoreactor consisting of a flow cell packed with immobilized haptens. The haptens (4-amino-L- or D-phenylalanine) are immobilized onto a hydroxysuccinimide-activated polymer (Affi-prep 10) via a tyramine spacer. Stereoselective antibodies, raised against 4-amino-L- or D-phenylalanine, are labeled with an acridinium ester. Stereoselective inhibition of binding of the acridinum-labeled antibodies to the immobilized hapten by amino acids takes place. Chiral recognition was observed not only for the hapten molecule but also for a series of different amino acids. One assay cycle including regeneration takes 6:30 min in the FIA mode and 4:40 min in the SIA mode. Using D-phenylalanine as a sample, the detection limit was found to be 6.13 pmol/ml (1.01 ng/ml) for the flow-injection immunoassay (FIIA) and 1.76 pmol/ml (0.29 ng/ml ) for the sequential-injection immunoassay (SIIA) which can be lowered to 0.22 pmol/ml (0.036 ng/ml) or 0.064 pmol/ml (0.01 ng/ml) by using a stopped flow system. The intra-assay repeatability was found to be about 5% RSD and the inter-assay repeatability below 6% (within 3 days).

Simultaneous feedback control of plasma rotation and stored energy on NSTX-U using neoclassical toroidal viscosity and neutral beam injection

NASA Astrophysics Data System (ADS)

Goumiri, I. R.; Rowley, C. W.; Sabbagh, S. A.; Gates, D. A.; Boyer, M. D.; Gerhardt, S. P.; Kolemen, E.; Menard, J. E.

2017-05-01

A model-based feedback system is presented enabling the simultaneous control of the stored energy through βn and the toroidal rotation profile of the plasma in National Spherical Torus eXperiment Upgrade device. Actuation is obtained using the momentum from six injected neutral beams and the neoclassical toroidal viscosity generated by applying three-dimensional magnetic fields. Based on a model of the momentum diffusion and torque balance, a feedback controller is designed and tested in closed-loop simulations using TRANSP, a time dependent transport analysis code, in predictive mode. Promising results for the ongoing experimental implementation of controllers are obtained.

Simultaneous feedback control of plasma rotation and stored energy on NSTX-U using neoclassical toroidal viscosity and neutral beam injection

PubMed Central

Goumiri, I. R.; Sabbagh, S. A.; Boyer, M. D.; Gerhardt, S. P.; Kolemen, E.; Menard, J. E.

2017-01-01

A model-based feedback system is presented enabling the simultaneous control of the stored energy through βn and the toroidal rotation profile of the plasma in National Spherical Torus eXperiment Upgrade device. Actuation is obtained using the momentum from six injected neutral beams and the neoclassical toroidal viscosity generated by applying three-dimensional magnetic fields. Based on a model of the momentum diffusion and torque balance, a feedback controller is designed and tested in closed-loop simulations using TRANSP, a time dependent transport analysis code, in predictive mode. Promising results for the ongoing experimental implementation of controllers are obtained. PMID:28435207

Simultaneous feedback control of plasma rotation and stored energy on NSTX-U using neoclassical toroidal viscosity and neutral beam injection

DOE PAGES

Goumiri, I. R.; Rowley, C. W.; Sabbagh, S. A.; ...

2017-02-23

In this study, a model-based feedback system is presented enabling the simultaneous control of the stored energy through β n and the toroidal rotation profile of the plasma in National Spherical Torus eXperiment Upgrade device. Actuation is obtained using the momentum from six injected neutral beams and the neoclassical toroidal viscosity generated by applying three-dimensional magnetic fields. Based on a model of the momentum diffusion and torque balance, a feedback controller is designed and tested in closed-loop simulations using TRANSP, a time dependent transport analysis code, in predictive mode. Promising results for the ongoing experimental implementation of controllers are obtained.

Intrathecal opioids versus epidural local anesthetics for labor analgesia: a meta-analysis.

PubMed

Bucklin, Brenda A; Chestnut, David H; Hawkins, Joy L

2002-01-01

Some anesthesiologists contend that intrathecal opioid administration has advantages over conventional epidural techniques during labor. Randomized clinical trials comparing analgesia and obstetric outcome using single-injection intrathecal opioids versus epidural local anesthetics suggest that intrathecal opioids provide comparable analgesia with few serious side effects. This meta-analysis compared the analgesic efficacy, side effects, and obstetric outcome of single-injection intrathecal opioid techniques versus epidural local anesthetics in laboring women. Relevant clinical studies were identified using electronic and manual searches of the literature covering the period from 1989 to 2000. Searches used the following descriptors: intrathecal analgesia, spinal opioids, epidural analgesia, epidural local anesthetics, and analgesia for labor. Data were extracted from 7 randomized clinical trials comparing analgesic measures, incidence of motor block, pruritus, nausea, hypotension, mode of delivery, and/or Apgar scores. Combined test results indicated comparable analgesic efficacy 15 to 20 minutes after injection with single-injection intrathecal opioid administration. Intrathecal opioid injections were associated with a greater incidence of pruritus (odds ratio, 14.01; 99% confidence interval, 6.9 to 28.3), but there was no difference in the incidence of nausea or in the method of delivery. Published studies suggest that intrathecal opioids provide comparable early labor analgesia when compared with epidural local anesthetics. Intrathecal opioid administration results in a greater incidence of pruritus. The choice of technique does not appear to affect the method of delivery.

Simultaneous determination of dechloranes, polybrominated diphenyl ethers and novel brominated flame retardants in food and serum.

PubMed

Sales, Carlos; Poma, Giulia; Malarvannan, Govindan; Portolés, Tania; Beltrán, Joaquin; Covaci, Adrian

2017-07-01

A sensitive method for the simultaneous quantification of dechloranes, polybrominated diphenyl ethers (PBDEs) and novel brominated flame retardants (NBFRs) has been developed for gas chromatography (GC) coupled to tandem mass spectrometry operating in electron capture negative ionization (ECNI) mode. The major advance has been achieved by combining selected ion monitoring (SIM) and multiple reaction monitoring (MRM) modes in well-defined time windows, to determine dechloranes, PBDEs and NBFRs at picogram per gram level in one single analysis in complex matrix biological samples. From the chromatographic point of view, efforts were devoted to study several injection modes using multimode inlet (MMI) in order to obtain low instrumental detection limits, necessary for trace compounds such as Dechlorane Plus (DP) isomers. Method performance was also evaluated: calibration curves were linear from 20 fg μL -1 to 100 pg μL -1 for the studied compounds, with method detection limits at levels of 50 fg g -1 for DPs. Repeatability and reproducibility, expressed as relative standard deviation, were better than 5% even in solvent vent mode for the injection of standards. The application to a wide range of complex samples (including food, human and animal serum samples) indicated a sensitive and reliable way to quantify at the picogram per gram level 4 halogenated norbornenes (HNs), Dechlorane Plus (anti-DP and syn-DP) and 2 of their homologues (Dechlorane-602 and Dechlorane-603), 11 PBDE congeners (no. 28, 47, 49, 66, 85, 99, 100, 153, 154, 183 and 209) and 5 novel BFRs, i.e. decabromodiphenyl ethane (DBDPE), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), hexabromobenzene (HBB), 2,3,4,5-tetrabromo-ethylhexyl-benzoate (TBB) and tetrabromophthalate (TBPH). Graphical Abstract GC-ECNI-MS/MS chromatograms showing the most sensitive transition for DPs when injecting 2 μL of a 16 fg/μL standard solution of s-DP and a-DP at three different source temperatures.

Watt-level widely tunable single-mode emission by injection-locking of a multimode Fabry-Perot quantum cascade laser

NASA Astrophysics Data System (ADS)

Chevalier, Paul; Piccardo, Marco; Anand, Sajant; Mejia, Enrique A.; Wang, Yongrui; Mansuripur, Tobias S.; Xie, Feng; Lascola, Kevin; Belyanin, Alexey; Capasso, Federico

2018-02-01

Free-running Fabry-Perot lasers normally operate in a single-mode regime until the pumping current is increased beyond the single-mode instability threshold, above which they evolve into a multimode state. As a result of this instability, the single-mode operation of these lasers is typically constrained to few percents of their output power range, this being an undesired limitation in spectroscopy applications. In order to expand the span of single-mode operation, we use an optical injection seed generated by an external-cavity single-mode laser source to force the Fabry-Perot quantum cascade laser into a single-mode state in the high current range, where it would otherwise operate in a multimode regime. Utilizing this approach, we achieve single-mode emission at room temperature with a tuning range of 36 cm-1 and stable continuous-wave output power exceeding 1 W at 4.5 μm. Far-field measurements show that a single transverse mode is emitted up to the highest optical power, indicating that the beam properties of the seeded Fabry-Perot laser remain unchanged as compared to free-running operation.

Multimode optical fibers: steady state mode exciter.

PubMed

Ikeda, M; Sugimura, A; Ikegami, T

1976-09-01

The steady state mode power distribution of the multimode graded index fiber was measured. A simple and effective steady state mode exciter was fabricated by an etching technique. Its insertion loss was 0.5 dB for an injection laser. Deviation in transmission characteristics of multimode graded index fibers can be avoided by using the steady state mode exciter.

Overview of recent HL-2A experiments

NASA Astrophysics Data System (ADS)

Duan, X. R.; Liu, Yi; Xu, M.; Yan, L. W.; Xu, Y.; Song, X. M.; Dong, J. Q.; Ding, X. T.; Chen, L. Y.; Lu, B.; Liu, D. Q.; Rao, J.; Xuan, W. M.; Yang, Q. W.; Zheng, G. Y.; Zou, X. L.; Liu, Y. Q.; Zhong, W. L.; Zhao, K. J.; Ji, X. Q.; Mao, W. C.; Wang, Q. M.; Li, Q.; Cao, J. Y.; Cao, Z.; Lei, G. J.; Zhang, J. H.; Li, X. D.; Bai, X. Y.; Cheng, J.; Chen, W.; Cui, Z. Y.; Delpech, L.; Diamond, P. H.; Dong, Y. B.; Ekedahl, A.; Hoang, T.; Huang, Y.; Ida, K.; Itoh, K.; Itoh, S.-I.; Isobe, M.; Inagaki, S.; Mazon, D.; Morita, S.; Peysson, Y.; Shi, Z. B.; Wang, X. G.; Xiao, G. L.; Yu, D. L.; Yu, L. M.; Zhang, Y. P.; Zhou, Y.; Cui, C. H.; Feng, B. B.; Huang, M.; Li, Y. G.; Li, B.; Li, G. S.; Li, H. J.; Li, Qing; Peng, J. F.; Wang, Y. Q.; Yuan, B. S.; Liu, Yong; HL-2A Team

2017-10-01

Since the last Fusion Energy Conference, significant progress has been made in the following areas. The first high coupling efficiency low-hybrid current drive (LHCD) with a passive-active multi-junction (PAM) antenna was successfully demonstrated in the H-mode on the HL-2A tokamak. Double critical impurity gradients of electromagnetic turbulence were observed in H-mode plasmas. Various ELM mitigation techniques have been investigated, including supersonic molecular beam injection (SMBI), impurity seeding, resonant magnetic perturbation (RMP) and low-hybrid wave (LHW). The ion internal transport barrier was observed in neutral beam injection (NBI) heated plasmas. Neoclassical tearing modes (NTMs) driven by the transient perturbation of local electron temperature during non-local thermal transport events have been observed, and a new type of non-local transport triggered by the ion fishbone was found. A long-lasting runaway electron plateau was achieved after argon injection and the runaway current was successfully suppressed by SMBI. It was found that low-n Alfvénic ion temperature gradient (AITG) modes can be destabilized in ohmic plasmas, even with weak magnetic shear and low-pressure gradients. For the first time, the synchronization of geodesic acoustic mode (GAM) and magnetic fluctuations was observed in edge plasmas, revealing frequency entrainment and phase lock. The spatiotemporal features of zonal flows were also studied using multi-channel correlation Doppler reflectometers.

A high-gain and high-efficiency X-band triaxial klystron amplifier with two-stage cascaded bunching cavities

NASA Astrophysics Data System (ADS)

Zhang, Wei; Ju, Jinchuan; Zhang, Jun; Zhong, Huihuang

2017-12-01

To achieve GW-level amplification output radiation at the X-band, a relativistic triaxial klystron amplifier with two-stage cascaded double-gap bunching cavities is investigated. The input cavity is optimized to obtain a high absorption rate of the external injection microwave. The cascaded bunching cavities are optimized to achieve a high depth of the fundamental harmonic current. A double-gap standing wave extractor is designed to improve the beam wave conversion efficiency. Two reflectors with high reflection coefficients both to the asymmetric mode and the TEM mode are employed to suppress the asymmetric mode competition and TEM mode microwave leakage. Particle-in-cell simulation results show that a high power microwave with a power of 2.53 GW and a frequency of 8.4 GHz is generated with a 690 kV, 9.3 kA electron beam excitation and a 25 kW seed microwave injection. Particularly, the achieved power conversion efficiency is about 40%, and the gain is as high as 50 dB. Meanwhile, there is insignificant self-excitation of the parasitic mode in the proposed structure by adopting the reflectors. The relative phase difference between the injected signals and the output microwaves keeps locked after the amplifier becomes saturated.

Multipoint Observations of Energetic Particle Injections and Substorm Activity During a Conjunction Between Magnetospheric Multiscale (MMS) and Van Allen Probes

NASA Astrophysics Data System (ADS)

Turner, D. L.; Fennell, J. F.; Blake, J. B.; Claudepierre, S. G.; Clemmons, J. H.; Jaynes, A. N.; Leonard, T.; Baker, D. N.; Cohen, I. J.; Gkioulidou, M.; Ukhorskiy, A. Y.; Mauk, B. H.; Gabrielse, C.; Angelopoulos, V.; Strangeway, R. J.; Kletzing, C. A.; Le Contel, O.; Spence, H. E.; Torbert, R. B.; Burch, J. L.; Reeves, G. D.

2017-11-01

This study examines multipoint observations during a conjunction between Magnetospheric Multiscale (MMS) and Van Allen Probes on 7 April 2016 in which a series of energetic particle injections occurred. With complementary data from Time History of Events and Macroscale Interactions during Substorms, Geotail, and Los Alamos National Laboratory spacecraft in geosynchronous orbit (16 spacecraft in total), we develop new insights on the nature of energetic particle injections associated with substorm activity. Despite this case involving only weak substorm activity (maximum AE <300 nT) during quiet geomagnetic conditions in steady, below-average solar wind, a complex series of at least six different electron injections was observed throughout the system. Intriguingly, only one corresponding ion injection was clearly observed. All ion and electron injections were observed at <600 keV only. MMS reveals detailed substructure within the largest electron injection. A relationship between injected electrons with energy <60 keV and enhanced whistler mode chorus wave activity is also established from Van Allen Probes and MMS. Drift mapping using a simplified magnetic field model provides estimates of the dispersionless injection boundary locations as a function of universal time, magnetic local time, and L shell. The analysis reveals that at least five electron injections, which were localized in magnetic local time, preceded a larger injection of both electrons and ions across nearly the entire nightside of the magnetosphere near geosynchronous orbit. The larger ion and electron injection did not penetrate to L < 6.6, but several of the smaller electron injections penetrated to L < 6.6. Due to the discrepancy between the number, penetration depth, and complexity of electron versus ion injections, this event presents challenges to the current conceptual models of energetic particle injections.

Multipoint Observations of Energetic Particle Injections and Substorm Activity During a Conjunction Between Magnetospheric Multiscale (MMS) and Van Allen Probes

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

Turner, Drew L.; Fennell, J. F.; Blake, J. B.

Here, this study examines multipoint observations during a conjunction between Magnetospheric Multiscale (MMS) and Van Allen Probes on 7 April 2016 in which a series of energetic particle injections occurred. With complementary data from Time History of Events and Macroscale Interactions during Substorms, Geotail, and Los Alamos National Laboratory spacecraft in geosynchronous orbit (16 spacecraft in total), we develop new insights on the nature of energetic particle injections associated with substorm activity. Despite this case involving only weak substorm activity (maximum AE <300 nT) during quiet geomagnetic conditions in steady, below-average solar wind, a complex series of at least sixmore » different electron injections was observed throughout the system. Intriguingly, only one corresponding ion injection was clearly observed. All ion and electron injections were observed at <600 keV only. MMS reveals detailed substructure within the largest electron injection. A relationship between injected electrons with energy <60 keV and enhanced whistler mode chorus wave activity is also established from Van Allen Probes and MMS. Drift mapping using a simplified magnetic field model provides estimates of the dispersionless injection boundary locations as a function of universal time, magnetic local time, and L shell. The analysis reveals that at least five electron injections, which were localized in magnetic local time, preceded a larger injection of both electrons and ions across nearly the entire nightside of the magnetosphere near geosynchronous orbit. The larger ion and electron injection did not penetrate to L < 6.6, but several of the smaller electron injections penetrated to L < 6.6. Due to the discrepancy between the number, penetration depth, and complexity of electron versus ion injections, this event presents challenges to the current conceptual models of energetic particle injections.« less

Multipoint Observations of Energetic Particle Injections and Substorm Activity During a Conjunction Between Magnetospheric Multiscale (MMS) and Van Allen Probes

DOE PAGES

Turner, Drew L.; Fennell, J. F.; Blake, J. B.; ...

2017-09-25

Here, this study examines multipoint observations during a conjunction between Magnetospheric Multiscale (MMS) and Van Allen Probes on 7 April 2016 in which a series of energetic particle injections occurred. With complementary data from Time History of Events and Macroscale Interactions during Substorms, Geotail, and Los Alamos National Laboratory spacecraft in geosynchronous orbit (16 spacecraft in total), we develop new insights on the nature of energetic particle injections associated with substorm activity. Despite this case involving only weak substorm activity (maximum AE <300 nT) during quiet geomagnetic conditions in steady, below-average solar wind, a complex series of at least sixmore » different electron injections was observed throughout the system. Intriguingly, only one corresponding ion injection was clearly observed. All ion and electron injections were observed at <600 keV only. MMS reveals detailed substructure within the largest electron injection. A relationship between injected electrons with energy <60 keV and enhanced whistler mode chorus wave activity is also established from Van Allen Probes and MMS. Drift mapping using a simplified magnetic field model provides estimates of the dispersionless injection boundary locations as a function of universal time, magnetic local time, and L shell. The analysis reveals that at least five electron injections, which were localized in magnetic local time, preceded a larger injection of both electrons and ions across nearly the entire nightside of the magnetosphere near geosynchronous orbit. The larger ion and electron injection did not penetrate to L < 6.6, but several of the smaller electron injections penetrated to L < 6.6. Due to the discrepancy between the number, penetration depth, and complexity of electron versus ion injections, this event presents challenges to the current conceptual models of energetic particle injections.« less

Thermally insensitive determination of the linewidth broadening factor in nanostructured semiconductor lasers using optical injection locking

PubMed Central

Wang, Cheng; Schires, Kevin; Osiński, Marek; Poole, Philip J.; Grillot, Frédéric

2016-01-01

In semiconductor lasers, current injection not only provides the optical gain, but also induces variation of the refractive index, as governed by the Kramers-Krönig relation. The linear coupling between the changes of the effective refractive index and the modal gain is described by the linewidth broadening factor, which is responsible for many static and dynamic features of semiconductor lasers. Intensive efforts have been made to characterize this factor in the past three decades. In this paper, we propose a simple, flexible technique for measuring the linewidth broadening factor of semiconductor lasers. It relies on the stable optical injection locking of semiconductor lasers, and the linewidth broadening factor is extracted from the residual side-modes, which are supported by the amplified spontaneous emission. This new technique has great advantages of insensitivity to thermal effects, the bias current, and the choice of injection-locked mode. In addition, it does not require the explicit knowledge of optical injection conditions, including the injection strength and the frequency detuning. The standard deviation of the measurements is less than 15%. PMID:27302301

Optical bistability in erbium-doped yttrium aluminum garnet crystal combined with a laser diode.

PubMed

Maeda, Y

1994-01-10

Optical bistability was observed in a simple structure of an injection laser diode combined with an erbium-doped yttrium aluminum garnet crystal. Since a hysteresis characteristic exists in the relationship between the wavelength and the injection current of a laser diode, an optical memory function capable of holding the output status is confirmed. In addition, an optical signal inversion was caused by the decrease of transmission of the erbium-doped yttrium aluminum garnet crystal against the red shift (principally mode hopping) of the laser diode. It is suggested that the switching time of this phenomenon is the time necessary for a mode hopping by current injection.

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

Yao, Juan; Zhou, Yufan; Sui, Xiao

Switchable ionic liquids (SWIL) play an important role in green chemistry. Due to the nature of SWIL chemistry, such as air sensitivity and pressure and temperature dependence, it is difficult to characterize SWIL using vacuum-based surface techniques. The fully CO2 loaded and none-loaded DBU and hexanol mixtures, a SWIL system, were analyzed in situ by time-of-flight secondary ion mass spectrometry (ToF-SIMS) coupled with the System for Analysis at the Liquid Vacuum Interface (SALVI), respectively. The DBU/Hexanol/CO2 SWIL was injected into the microchannel before liquid SIMS analysis. Bi3+ primary ion beam was used. The positive and negative spectra of the SWILmore » chemical components are presented. The characteristic peaks m/z 153 (reduced DBU) in the positive mode and m/z 101 (oxidized hexanol) in negative mode were observed. In addition, ion pair peaks including m/z 253, 319, 305, 451 in the positive mode and m/z 145, 223, 257 in the negative mode are first observed using this approach. These results demonstrate that the SALVI microfluidic reactor enables the vacuum-based surface technique (i.e., ToF-SIMS) for in situ characterization of challenging liquid samples such as ionic liquids.« less

Mitigation of divertor heat flux by high-frequency ELM pacing with non-fuel pellet injection in DIII-D

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

Bortolon, A.; Maingi, R.; Mansfield, D. K.

Experiments have been conducted on DIII-D investigating high repetition rate injection of non-fuel pellets as a tool for pacing Edge Localized Modes (ELMs) and mitigating their transient divertor heat loads. Effective ELM pacing was obtained with injection of Li granules in different H-mode scenarios, at frequencies 3–5 times larger than the natural ELM frequency, with subsequent reduction of strike-point heat flux. However, in scenarios with high pedestal density (~6 × 10 19 m –3), the magnitude of granule triggered ELMs shows a broad distribution, in terms of stored energy loss and peak heat flux, challenging the effectiveness of ELM mitigation.more » Furthermore, transient heat-flux deposition correlated with granule injections was observed far from the strike-points. As a result, field line tracing suggest this phenomenon to be consistent with particle loss into the mid-plane far scrape-off layer, at toroidal location of the granule injection.« less

Mitigation of divertor heat flux by high-frequency ELM pacing with non-fuel pellet injection in DIII-D

DOE PAGES

Bortolon, A.; Maingi, R.; Mansfield, D. K.; ...

2017-03-23

Experiments have been conducted on DIII-D investigating high repetition rate injection of non-fuel pellets as a tool for pacing Edge Localized Modes (ELMs) and mitigating their transient divertor heat loads. Effective ELM pacing was obtained with injection of Li granules in different H-mode scenarios, at frequencies 3–5 times larger than the natural ELM frequency, with subsequent reduction of strike-point heat flux. However, in scenarios with high pedestal density (~6 × 10 19 m –3), the magnitude of granule triggered ELMs shows a broad distribution, in terms of stored energy loss and peak heat flux, challenging the effectiveness of ELM mitigation.more » Furthermore, transient heat-flux deposition correlated with granule injections was observed far from the strike-points. As a result, field line tracing suggest this phenomenon to be consistent with particle loss into the mid-plane far scrape-off layer, at toroidal location of the granule injection.« less

Steam injection pilot study in a contaminated fractured limestone (Maine, USA): Modeling and analysis of borehole radar reflection data

USGS Publications Warehouse

Gregoire, C.; Lane, J.W.; Joesten, P.K.

2005-01-01

Steam-enhanced remediation (SER) has been successfully used to remove DNAPL and LNAPL contaminants in porous media. Between August and November 2002, SER was tested in fractured limestone at the former Loring Air Force Base, in Maine, USA. During the SER investigation, the U.S. Geological Survey conducted a series of borehole radar surveys to evaluate the effectiveness of radar methods for monitoring the movement of steam and heat through the fractured limestone. The data were collected before steam injection, 10 days after the beginning of injection, and at the end of injection. In this paper, reflection-mode borehole radar data from wells JBW-7816 and JBW-7817A are presented and discussed. Theoretical modeling was performed to predict the variation of fracture reflectivity owed to heating, to show displacement of water and to assess the effect of SER at the site. Analysis of the radar profile data indicates some variations resulting from heating (increase of continuity of reflectors, attenuation of deeper reflections) but no substantial variation of traveltimes. Spectral content analysis of several individual reflections surrounding the boreholes was used to investigate the replacement of water by steam in the fractures. Observed decrease in radar reflectivity was too small to be explained by a replacement of water by steam, except for two high-amplitude reflectors, which disappeared near the end of the injection; moreover, no change of polarity, consistent with steam replacing water, was observed. The decrease of amplitude was greater for reflectors near well JBW-7817A and is explained by a greater heating around this well.

Multi-species impurity granule injection and mass deposition projections in NSTX-U discharges

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

Lunsford, R.; Bortolon, A.; Roquemore, A. L.

Here, by employing a neutral gas shielding (NGS) model to characterize impurity granule injection, the ablation rates for three different species of granule: lithium, boron, and carbon, are determined. Utilizing the duration of ablation events recorded on experiments performed at DIII-D to calibrate the NGS model, we quantify the ablation rate with respect to the plasma density profile. The species-specific granule shielding constant is then used to model granule ablation within NSTX-U discharges. Simulations of 300, 500 and 700 micron diameter granules injected at 50 m s –1 are presented for NSTX-U L-mode type plasmas, as well as H-mode dischargesmore » with low natural ELM frequency. Additionally, ablation calculations of 500 micron granules of each species are presented at velocities ranging from 50–150 m s –1. In H-mode discharges these simulations show that the majority of the injected granule is ablated within or just past the edge steep gradient region. At this radial position, the perturbation to the background plasma generated by the ablating granule can lead to conditions advantageous for the rapid triggering of ELM crashes.« less

High efficiency single transverse mode photonic band crystal lasers with low vertical divergence

NASA Astrophysics Data System (ADS)

Zhao, Shaoyu; Qu, Hongwei; Liu, Yun; Li, Lunhua; Chen, Yang; Zhou, Xuyan; Lin, Yuzhe; Liu, Anjin; Qi, Aiyi; Zheng, Wanhua

2016-10-01

High efficiency 980 nm longitudinal photonic band crystal (PBC) edge emitting laser diodes are designed and fabricated. The calculated results show that eight periods of Al0.1Ga0.9As and Al0.25Ga0.75As layer pairs can reduce the vertical far field divergence to 10.6° full width at half maximum (FWHM). The broad area (BA) lasers show a very high internal quantum efficiency ηi of 98% and low internal loss αi of 1.92 cm-1. Ridge waveguide (RW) lasers with 3 mm cavity length and 5um strip width provide 430 mW stable single transverse mode output at 500 mA injection current with power conversion efficiency (PCE) of 47% under continuous wave (CW) mode. A maximum PCE of 50% is obtained at the 300 mA injection current. A very low vertical far field divergence of 9.4° is obtained at 100 mA injection. At 500 mA injection, the vertical far field divergence increases to 11°, the beam quality factors M2 values are 1.707 in vertical direction and 1.769 in lateral direction.

Multi-species impurity granule injection and mass deposition projections in NSTX-U discharges

DOE PAGES

Lunsford, R.; Bortolon, A.; Roquemore, A. L.; ...

2017-05-16

Here, by employing a neutral gas shielding (NGS) model to characterize impurity granule injection, the ablation rates for three different species of granule: lithium, boron, and carbon, are determined. Utilizing the duration of ablation events recorded on experiments performed at DIII-D to calibrate the NGS model, we quantify the ablation rate with respect to the plasma density profile. The species-specific granule shielding constant is then used to model granule ablation within NSTX-U discharges. Simulations of 300, 500 and 700 micron diameter granules injected at 50 m s –1 are presented for NSTX-U L-mode type plasmas, as well as H-mode dischargesmore » with low natural ELM frequency. Additionally, ablation calculations of 500 micron granules of each species are presented at velocities ranging from 50–150 m s –1. In H-mode discharges these simulations show that the majority of the injected granule is ablated within or just past the edge steep gradient region. At this radial position, the perturbation to the background plasma generated by the ablating granule can lead to conditions advantageous for the rapid triggering of ELM crashes.« less

Experiences from First Top-Off Injection at the Stanford Synchrotron Radiation Lightsource

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

Bauer, J.M.; Liu, J.C.; Prinz, A.

2009-12-11

As the Stanford Synchrotron Radiation Lightsource (SSRL) of the SLAC National Accelerator Laboratory (SLAC) is moving toward Top-Off injection mode, SLAC's Radiation Protection Department is working with SSRL on minimizing the radiological hazards of this mode. One such hazard is radiation that is created inside the accelerator concrete enclosure by injected beam. Since during Top-Off injection the stoppers that would otherwise isolate the storage ring from the experimental area stay open, the stoppers no longer prevent such radiation from reaching the experimental area. The level of this stray radiation was measured in April 2008 during the first Top-Off injection tests.more » They revealed radiation dose rates of up to 18 microSv/h (1.8 millirem/h) outside the experimental hutches, significantly higher than our goal of 1 microSv/h (0.1 millirem/h). Non-optimal injection increased the measured dose rates by a factor two. Further tests in 2008 indicated that subsequent improvements by SSRL to the injection system have reduced the dose rates to acceptable levels. This presentation describes the studies performed before the Top-Off tests, the tests themselves and their major results (both under initial conditions and after improvements were implemented), and presents the controls being implemented for full and routine Top-Off injection.« less

Evaluation of a direct injection nebulizer interface for flow injection analysis and high performance liquid chromatography with inductively coupled plasma-atomic emission spectroscopic detection

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

LaFreniere, K.E.

A direct injection nebulizer (DIN) was designed, developed and evaluated to determine its potential utilization as an effective interface for flow injection analysis (FIA) and high performance liquid chromatography (HPLC) coupled with inductively coupled plasma-atomic emission spectroscopic detection. The analytical figures of merit for the DIN when used as an interface for FIA-ICP-AES were found to be comparable to or better than those obtained with conventional pneumatic nebulization in terms of limits of detection (LODs), reproducibility, linearity, and interelement effects. In the HPLC mode, the LODDs were found to be comparable to those obtained by continuous-flow sample introduction into themore » ICP, or inferior by up to only a factor of four. Stable plasma operation was maintained for the DIN sample introduction of a variety of pure organic solvents, including acetonitrile, methanol, methyl-isobutylketone, and pyridine. The HPLC-DIN-ICP-AES facility was specifically applied for the speciation of inorganic and organo-metallic species contained in synthetic mixtures, vanilla extracts and a variety of energy-related materials, such as shale oil process water, coal extracts, shale oil, crude oil, and an SRC II. Suggestions for future research are also considered.« less

Development of colorless distributed combustion for gas turbine application

NASA Astrophysics Data System (ADS)

Arghode, Vaibhav Kumar

Colorless Distributed Combustion (CDC) is investigated for gas turbine engine application due to its benefit for ultra-low pollutant emission, improved pattern factor, low noise emission, stable combustion and low pressure drop, alleviation of combustion instabilities and increased life of turbine blades with less air cooling requirements. The CDC is characterized by discrete and direct injection of fuel and air at high velocity and the reaction zone is stabilized due to controlled aerodynamics inside the combustor and wider (radially) shear layer mixing. Mixing between the injected air and product gases to form hot and diluted oxidant is required followed by rapid mixing with the fuel. This results in distributed reaction zone instead of a concentrated flame front as observed in conventional diffusion flames and hence, to avoid hot spot regions and provide reduced NOx and CO emissions. The focus of this dissertation is to develop and demonstrate CDC for application to stationary gas turbine combustors which generally operate at thermal intensity of 15MW/m3-atm. However, higher thermal intensity is desirable to reduce hardware costs due to smaller weight and volume of the combustors. Design of high thermal intensity CDC combustor requires careful control of critical parameters, such as, gas recirculation, fuel/oxidizer mixing and residence time characteristics via careful selection of different air and fuel injection configurations to achieve desirable combustion characteristics. This dissertation examines sequential development of low emission colorless distributed combustor operating from thermal intensity of 5MW/m3-atm up to 198MW/m3-atm. Initially, various fuel and air injection configurations were investigated at a low thermal intensity of 5MW/m 3-atm. Further investigations were performed for a simpler combustor having single air and fuel injection ports for medium thermal intensity range of 28-57MW/m3-atm. Among the flow configurations investigated, reverse cross-flow configuration was found to give more favorable results possibly due to higher residence time because of reverse flow geometry and faster mixing with the fuel injection in cross-flow. This configuration was investigated in detail by further reducing the combustor volume to give ultra-high thermal intensity of up to 198MW/m3-atm. At thermal intensity of 53MW/m3-atm NO emissions were 4ppm in non-premixed mode and 1ppm in premixed mode and CO emissions were 30ppm in both the modes. The pressure loss was less than 5% and heat loss was less than 15%. The pressure fluctuations were less than 0.025% suggesting very stable combustion. At ultra-high thermal intensity of 170MW/m3-atm NO emissions were 8ppm and 3ppm in non-premixed and premixed modes respectively and CO emissions were about 100ppm in both the modes. Dilution of fuel with nitrogen, carbon dioxide and air resulted in significant reduction in NO emission in non-premixed mode from 8ppm to about 2ppm. Methane was used as fuel for all these investigations. Liquid fuel (ethanol) was also tested and very low NO emission of about 6ppm was obtained in direct injection mode and 2ppm in premixed prevaporized mode. CO emission of about 200ppm was observed in both the modes.

Electron cyclotron heating can drastically alter reversed shear Alfvén eigenmode activity in DIII-D through finite pressure effects

NASA Astrophysics Data System (ADS)

Van Zeeland, M. A.; Heidbrink, W. W.; Sharapov, S. E.; Spong, D.; Cappa, A.; Chen, Xi; Collins, C.; García-Muñoz, M.; Gorelenkov, N. N.; Kramer, G. J.; Lauber, P.; Lin, Z.; Petty, C.

2016-11-01

A recent DIII-D experiment investigating the impact of electron cyclotron heating (ECH) on neutral beam driven reversed shear Alfvén eigenmode (RSAE) activity is presented. The experiment includes variations of ECH injection location and timing, current ramp rate, beam injection geometry (on/off-axis), and neutral beam power. Essentially all variations carried out in this experiment were observed to change the impact of ECH on AE activity significantly. In some cases, RSAEs were observed to be enhanced with ECH near the off-axis minimum in magnetic safety factor ({{q}\\min} ), in contrast to the original DIII-D experiments where the modes were absent when ECH was deposited near {{q}\\min} . It is found that during intervals when the geodesic acoustic mode (GAM) frequency at {{q}\\min} is elevated and the calculated RSAE minimum frequency, including contributions from thermal plasma gradients, is very near or above the nominal TAE frequency (f TAE), RSAE activity is not observed or RSAEs with a much reduced frequency sweep range are found. This condition is primarily brought about by ECH modification of the local electron temperature (T e) which can raise both the local T e at {{q}\\min} as well as its gradient. A q-evolution model that incorporates this reduction in RSAE frequency sweep range is in agreement with the observed spectra and appears to capture the relative balance of TAE or RSAE-like modes throughout the current ramp phase of over 38 DIII-D discharges. Detailed ideal MHD calculations using the NOVA code show both modification of plasma pressure and pressure gradient at {{q}\\min} play an important role in modifying the RSAE activity. Analysis of the ECH injection near the {{q}\\min} case where no frequency sweeping RSAEs are observed shows the typical RSAE is no longer an eigenmode of the system. What remains is an eigenmode with poloidal harmonic content reminiscent of the standard RSAE, but absent of the typical frequency sweeping behavior. The remaining eigenmode is also often strongly coupled to gap TAEs. Analysis with the non-perturbative gyro fluid code TAEFL confirms this change in RSAE activity and also shows a large drop in the resultant mode growth rates.

Electron cyclotron heating can drastically alter reversed shear Alfvén eigenmode activity in DIII-D through finite pressure effects

DOE PAGES

Van Zeeland, M. A.; Heidbrink, W. W.; Sharapov, S. E.; ...

2016-07-22

Here, a recent DIII-D experiment investigating the impact of electron cyclotron heating (ECH) on neutral beam driven reversed shear Alfvén eigenmode (RSAE) activity is presented. The experiment includes variations of ECH injection location and timing, current ramp rate, beam injection geometry (on/off-axis), and neutral beam power. Essentially all variations carried out in this experiment were observed to change the impact of ECH on AE activity significantly. In some cases, RSAEs were observed to be enhanced with ECH near the off-axis minimum in magnetic safety factor (more » $${{q}_{\\min}}$$ ), in contrast to the original DIII-D experiments where the modes were absent when ECH was deposited near $${{q}_{\\min}}$$ . It is found that during intervals when the geodesic acoustic mode (GAM) frequency at $${{q}_{\\min}}$$ is elevated and the calculated RSAE minimum frequency, including contributions from thermal plasma gradients, is very near or above the nominal TAE frequency (f TAE), RSAE activity is not observed or RSAEs with a much reduced frequency sweep range are found. This condition is primarily brought about by ECH modification of the local electron temperature (T e) which can raise both the local T e at $${{q}_{\\min}}$$ as well as its gradient. A q-evolution model that incorporates this reduction in RSAE frequency sweep range is in agreement with the observed spectra and appears to capture the relative balance of TAE or RSAE-like modes throughout the current ramp phase of over 38 DIII-D discharges. Detailed ideal MHD calculations using the NOVA code show both modification of plasma pressure and pressure gradient at $${{q}_{\\min}}$$ play an important role in modifying the RSAE activity. Analysis of the ECH injection near the $${{q}_{\\min}}$$ case where no frequency sweeping RSAEs are observed shows the typical RSAE is no longer an eigenmode of the system. What remains is an eigenmode with poloidal harmonic content reminiscent of the standard RSAE, but absent of the typical frequency sweeping behavior. The remaining eigenmode is also often strongly coupled to gap TAEs. Analysis with the non-perturbative gyro fluid code TAEFL confirms this change in RSAE activity and also shows a large drop in the resultant mode growth rates.« less

Phenomenology of beam driven modes in the field reversed configuration

NASA Astrophysics Data System (ADS)

Magee, Richard; Bolte, Nathan; Clary, Ryan; Necas, Ales; Korepanov, Sergey; Smirnov, Artem; Thompson, Matthew; Tajima, Toshiki; THE TAE Team

2016-10-01

The C-2U experiment offers a unique plasma environment combining a high beta field reversed configuration (FRC) embedded in a low beta magnetic mirror with high power neutral beam injection. The beams are injected tangentially into a modest magnetic field so that the orbits of the resulting fast ions encircle the entire plasma. These large orbit particles sustain and stabilize the plasma and suppress turbulence. Measurements of magnetic fluctuations at the edge of the plasma reveal the presence of three coherent beam driven modes: a low frequency, chirping mode, a mode near the ion cyclotron frequency, and a high frequency compressional Alfven mode. Remarkably, none of these modes are observed to have a deleterious effect on global plasma confinement. In fact, the cyclotron mode has the beneficial effect of dramatically enhancing the DD fusion reaction rate by drawing a trail from the plasma ion energy distribution on a sub-collisional timescale. In this presentation, we experimentally characterize the beam driven modes in the C-2U FRC with data from multiple diagnostics including magnetics, spectroscopy, neutral particle analyzers and fusion product diagnostics. Results are compared to a particle-in-cell simulation in a simplified geometry.

FIBER AND INTEGRATED OPTICS: Anisotropic waveguides with an elliptic stress-inducing cladding and a circular core

NASA Astrophysics Data System (ADS)

Arutyunyan, Z. É.; Grudinin, A. B.; Gur'yanov, A. N.; Gusovskiĭ, D. D.; Dianov, Evgenii M.; Ignat'ev, S. V.; Smirnov, O. B.

1990-10-01

A technology of fabrication of anisotropic single-mode fiber waveguides with an elliptic stress-inducing cladding and a circular core was developed. This technology was used to make fiber waveguides with a birefringence (1-3) × 10 - 4, a coefficient representing the coupling between the polarization modes h = (5-7) × 10 - 5 m - 1, and optical losses a = 0.5 dB/km in the vicinity of 1.6 μm. A comparison was made of the experimental data with the results of a theoretical analysis. It was found that certain mechanisms restricted the ability of these waveguides to maintain a constant polarization of the injected linearly polarized radiation.

Prompt triggering of edge localized modes through lithium granule injection on EAST

NASA Astrophysics Data System (ADS)

Lunsford, Robert; Sun, Z.; Hu, J. S.; Xu, W.; Zuo, G. Z.; Gong, X. Z.; Wan, B. N.; Li, J. G.; Huang, M.; Maingi, R.; Diallo, A.; Tritz, K.; the EAST Team

2017-10-01

We report successful triggering of edge localized mode (ELMs) in EAST with Lithium (Li) micropellets, and the observed dependence of ELM triggering efficiency on granule size. ELM control is essential for successful ITER operation throughout the entire campaign, relying on magnetic perturbations for ELM suppression and ELM frequency enhancement via pellet injection. To separate the task of fueling from ELM pacing, we initiate the prompt generation of ELMs via impurity granule injection. Lithium granules ranging in size from 200 - 1000 microns are mechanically injected into upper-single null EAST long pulse H-mode discharges. The injections are monitored for their effect on high Z impurity accumulation and to assess the pressure perturbation required for reliable ELM triggering. We have determined that granules of diameter larger than 600 microns (corresponding to 5.2 x 1018 Li atoms) are successful at triggering ELMs more than 90% of the time. The triggering efficiency drops precipitously to less than 40% as the granule size is reduced to 400 microns (1.5 x 1018 Li atoms), indicating a triggering threshold has been crossed. Using this information an optimal impurity granule size which will regularly trigger a prompt ELM in these EAST discharges is determined. Coupling these results with alternate discharge scenarios on EAST and similar experiments performed on DIII-D provides the possibility of extrapolation to future devices.

Droplet Breakup in Expansion-contraction Microchannels

PubMed Central

Zhu, Pingan; Kong, Tiantian; Lei, Leyan; Tian, Xiaowei; Kang, Zhanxiao; Wang, Liqiu

2016-01-01

We investigate the influences of expansion-contraction microchannels on droplet breakup in capillary microfluidic devices. With variations in channel dimension, local shear stresses at the injection nozzle and focusing orifice vary, significantly impacting flow behavior including droplet breakup locations and breakup modes. We observe transition of droplet breakup location from focusing orifice to injection nozzle, and three distinct types of recently-reported tip-multi-breaking modes. By balancing local shear stresses and interfacial tension effects, we determine the critical condition for breakup location transition, and characterize the tip-multi-breaking mode quantitatively. In addition, we identify the mechanism responsible for the periodic oscillation of inner fluid tip in tip-multi-breaking mode. Our results offer fundamental understanding of two-phase flow behaviors in expansion-contraction microstructures, and would benefit droplet generation, manipulation and design of microfluidic devices. PMID:26899018

Effects of injection nozzle exit width on rotating detonation engine

NASA Astrophysics Data System (ADS)

Sun, Jian; Zhou, Jin; Liu, Shijie; Lin, Zhiyong; Cai, Jianhua

2017-11-01

A series of numerical simulations of RDE modeling real injection nozzles with different exit widths are performed in this paper. The effects of nozzle exit width on chamber inlet state, plenum flowfield and detonation propagation are analyzed. The results are compared with that using an ideal injection model. Although the ideal injection model is a good approximation method to model RDE inlet, the two-dimensional effects of real nozzles are ignored in the ideal injection model so that some complicated phenomena such as the reflected waves caused by the nozzle walls and the reversed flow into the nozzles can not be modeled accurately. Additionally, the ideal injection model overpredicts the block ratio. In all the cases that stabilize at one-wave mode, the block ratio increases as the nozzle exit width gets smaller. The dual-wave mode case also has a relatively high block ratio. A pressure oscillation in the plenum with the same main frequency with the rotating detonation wave is observed. A parameter σ is applied to describe the non-uniformity in the plenum. σ increases as the nozzle exit width gets larger. Under some condition, the heat release on the interface of fresh premixed gas layer and detonation products can be strong enough to induce a new detonation wave. A spontaneous mode-transition process is observed for the smallest exit width case. Due to the detonation products existing in the premixed gas layer before the detonation wave, the detonation wave will propagate through reactants and products alternately, and therefore its strength will vary with time, especially near the chamber inlet. This tendency gets weaker as the injection nozzle exit width increases.

Direct Method Transcription for a Human-Class Translunar Injection Trajectory Optimization

NASA Technical Reports Server (NTRS)

Witzberger, Kevin E.; Zeiler, Tom

2012-01-01

This paper presents a new trajectory optimization software package developed in the framework of a low-to-high fidelity 3 degrees-of-freedom (DOF)/6-DOF vehicle simulation program named Mission Analysis Simulation Tool in Fortran (MASTIF) and its application to a translunar trajectory optimization problem. The functionality of the developed optimization package is implemented as a new "mode" in generalized settings to make it applicable for a general trajectory optimization problem. In doing so, a direct optimization method using collocation is employed for solving the problem. Trajectory optimization problems in MASTIF are transcribed to a constrained nonlinear programming (NLP) problem and solved with SNOPT, a commercially available NLP solver. A detailed description of the optimization software developed is provided as well as the transcription specifics for the translunar injection (TLI) problem. The analysis includes a 3-DOF trajectory TLI optimization and a 3-DOF vehicle TLI simulation using closed-loop guidance.

Highly selective solid-phase extraction and large volume injection for the robust gas chromatography-mass spectrometric analysis of TCA and TBA in wines.

PubMed

Insa, S; Anticó, E; Ferreira, V

2005-09-30

A reliable solid-phase extraction (SPE) method for the simultaneous determination of 2,4,6-trichloroanisole (TCA) and 2,4,6-tribromoanisole (TBA) in wines has been developed. In the proposed procedure 50 mL of wine are extracted in a 1 mL cartridge filled with 50 mg of LiChrolut EN resins. Most wine volatiles are washed up with 12.5 mL of a water:methanol solution (70%, v/v) containing 1% of NaHCO3. Analytes are further eluted with 0.6 mL of dichloromethane. A 40 microL aliquot of this extract is directly injected into a PTV injector operated in the solvent split mode, and analysed by gas chromatography (GC)-ion trap mass spectrometry using the selected ion storage mode. The solid-phase extraction, including sample volume and rinsing and elution solvents, and the large volume GC injection have been carefully evaluated and optimized. The resulting method is precise (RSD (%) < 6% at 100 ng L(-1)), sensitive (LOD were 0.2 and 0.4 ng/L for TCA and TBA, respectively), robust (the absolute recoveries of both analytes are higher than 80% and consistent wine to wine) and friendly to the GC-MS system (the extract is clean, simple and free from non-volatiles).

Low-Cost Production of Composite Bushings for Jet Engine Applications

NASA Technical Reports Server (NTRS)

Gray, Robert A.

1998-01-01

The objectives of this research program were to reduce the manufacturing costs of variable stator vane bushings by 1) eliminating the expensive carbon fiber braiding operation, 2) replacing the batch mode impregnation, B-stage, and cutting operations with a continuous process, and 3) reducing the molding cycle and machining operations with injection molding to achieve near-net shapes. Braided bushings were successfully fabricated with both AMB-17XLD and AMB-TPD resin systems. The composite bushings achieved high glass transition temperature after post-cure (+300 C) and comparable weight loss to the PNM-15 bushings. ANM-17XLD bushings made with "batch-mode" molding compound (at 0.5 in. fiber length) achieved a +300 lb-force flange break strength which was superior to the continuous braided-fiber reinforced bushing. The non-MDA resin technology developed in this contract appears attractive for bushing applications that do not exceed a 300 C use temperature. Two thermoplastic polyimide resins were synthesized in order to generate injection molding compound powders. Excellent processing results were obtained at injection temperatures in excess of 300 C. Micro-tensile specimens were produced from each resin type and the Tg measurements (by TMA) for these samples were equivalent to AURUM(R). Thermal Gravimetric Analysis (TGA) conducted at 10 C/min showed that the non-MDA AMB-type polyimide thermoplastics had comparable weight loss to PMR-15 up to 500 C.

Electron beam injection during active experiments. I - Electromagnetic wave emissions

NASA Technical Reports Server (NTRS)

Winglee, R. M.; Kellogg, P. J.

1990-01-01

The wave emissions produced in Echo 7 experiment by active injections of electron beams were investigated to determine the properties of the electromagnetic and electrostatic fields for both the field-aligned and cross-field injection in such experiments and to evaluate the sources of free energy and relative efficiencies for the generation of the VLF and HF emissions. It is shown that, for typical beam energies in active experiments, electromagnetic effects do not substantially change the bulk properties of the beam, spacecraft charging, and plasma particle acceleration. Through simulations, beam-generated whistlers; fundamental z-mode and harmonic x-mode radiation; and electrostatic electron-cyclotron, upper-hybrid, Langmuir, and lower-hybrid waves were identified. The characteristics of the observed wave spectra were found to be sensitive to both the ratio of the electron plasma frequency to the cyclotron frequency and the angle of injection relative to the magnetic field.

Dependence of injection locking of a TEA CO2 laser on intensity of injected radiation

NASA Technical Reports Server (NTRS)

Oppenheim, U. P.; Menzies, R. T.; Kavaya, M. J.

1982-01-01

The results of an experimental study to determine the minimum required injected power to control the output frequency of a TEA CO2 laser are reported. A CW CO2 waveguide laser was used as the injection oscillator. Both the power and the frequency of the injected radiation were varied, while the TEA resonator cavity length was adjusted to match the frequency of the injected signal. Single-longitudinal mode (SLM) TEA laser radiation was produced for injected power levels which are several orders of magnitude below those previously reported. The ratio of SLM output power to injection power exceeded 10 to the 12th at the lowest levels of injected intensity.

Thermally Stratified Compression Ignition: A new advanced low temperature combustion mode with load flexibility

DOE PAGES

Lawler, Benjamin; Splitter, Derek; Szybist, James; ...

2017-03-01

We introduce a new advanced combustion mode, called Thermally Stratified Compression Ignition (TSCI), which uses direct water injection to control both the average temperature and the temperature distribution prior to ignition, thereby providing cycle-to-cycle control over the start and rate of heat release in Low Temperature Combustion (LTC). Experiments were conducted to fundamentally understand the effects of water injection on heat release in LTC. Our results show that water injection retards the start of combustion due to the latent heat of vaporization of the injected water. Furthermore, for start of water injection timings between 20 and 70 degrees before topmore » dead center, combustion is significantly elongated compared to without water injection. The 10–90% burn duration with 6.6 and 9.0 mg of water per cycle was 77% and 146% longer than without water injection, respectively. Forced thermal stratification result from a direct water injection which reduces the heat release rate by local evaporative cooling. Finally, the load limits with and without water injection were determined experimentally. Without water injection, the load range was 2.3–3.6 bar gross IMEP. By using water injection to control heat release, the load range in TSCI was 2.3–8.4 bar gross IMEP, which is a range expansion of over 350%. These results demonstrate that direct water injection can provide significant improvements to both controllability and the range of operability of LTC, thereby resolving the major challenges associated with HCCI.« less

Thermally Stratified Compression Ignition: A new advanced low temperature combustion mode with load flexibility

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

Lawler, Benjamin; Splitter, Derek; Szybist, James

We introduce a new advanced combustion mode, called Thermally Stratified Compression Ignition (TSCI), which uses direct water injection to control both the average temperature and the temperature distribution prior to ignition, thereby providing cycle-to-cycle control over the start and rate of heat release in Low Temperature Combustion (LTC). Experiments were conducted to fundamentally understand the effects of water injection on heat release in LTC. Our results show that water injection retards the start of combustion due to the latent heat of vaporization of the injected water. Furthermore, for start of water injection timings between 20 and 70 degrees before topmore » dead center, combustion is significantly elongated compared to without water injection. The 10–90% burn duration with 6.6 and 9.0 mg of water per cycle was 77% and 146% longer than without water injection, respectively. Forced thermal stratification result from a direct water injection which reduces the heat release rate by local evaporative cooling. Finally, the load limits with and without water injection were determined experimentally. Without water injection, the load range was 2.3–3.6 bar gross IMEP. By using water injection to control heat release, the load range in TSCI was 2.3–8.4 bar gross IMEP, which is a range expansion of over 350%. These results demonstrate that direct water injection can provide significant improvements to both controllability and the range of operability of LTC, thereby resolving the major challenges associated with HCCI.« less

Injection-seeded operation of a Q-switched Cr,Tm,Ho:YAG laser

NASA Technical Reports Server (NTRS)

Henderson, Sammy W.; Hale, Charley P.; Magee, James R.

1991-01-01

Single-frequency Tm,Ho:YAG lasers operating near 2 microns are attractive sources for several applications including eye-safe laser radar (lidar) and pumping of AgGaSe2 parametric oscillators for efficient generation of longer wavelengths. As part of a program to develop a coherent lidar system using Tm,Ho:YAG lasers, a diode laser-pumped tunable CW single-longitudinal-mode (SLM) Cr:Tm:Ho:YAG laser and a flashlamp-pumped single-transverse-mode Q-switched Cr,Tm,Ho:YAG laser were developed. The CW laser was used to injection-seed the flashlamp-pumped laser, resulting in SLM Q-switched output. Operational characteristics of the CW and Q-switched lasers and injection-seeding results are reported.

Statistical Properties of a Ring Laser with Injected Signal and Backscattering

NASA Astrophysics Data System (ADS)

Leng, Feng; Zhu, Shi-Qun

2001-01-01

The statistical properties of a homogeneously broadened ring laser with an injected signal are investigated and the normalized two-mode intensity auto- and cross-correlation functions are calculated by a full saturation laser theory with backscattering. The theoretical predictions are in good agreement with the experimental measurements. Further investigation reveals that the backscattering can reduce the fluctuations in the system while the full saturation effect plays a major role when the laser is operated above threshold. It is also quite important to notice that the injected signal can drive the weak mode from incoherent light to coherent light. The project supported by National Natural Science Foundation of China (Grant No. 19874046) and Natural Science Foundation of Jiangsu Education Commission of China

Lightning Pin Injection Test: MOSFETS in "ON" State

NASA Technical Reports Server (NTRS)

Ely, Jay J.; Nguyen, Truong X.; Szatkowski, George N.; Koppen, Sandra V.; Mielnik, John J.; Vaughan, Roger K.; Saha, Sankalita; Wysocki, Philip F.; Celaya, Jose R.

2011-01-01

The test objective was to evaluate MOSFETs for induced fault modes caused by pin-injecting a standard lightning waveform into them while operating. Lightning Pin-Injection testing was performed at NASA LaRC. Subsequent fault-mode and aging studies were performed by NASA ARC researchers using the Aging and Characterization Platform for semiconductor components. This report documents the test process and results, to provide a basis for subsequent lightning tests. The ultimate IVHM goal is to apply prognostic and health management algorithms using the features extracted during aging to allow calculation of expected remaining useful life. A survey of damage assessment techniques based upon inspection is provided, and includes data for optical microscope and X-ray inspection. Preliminary damage assessments based upon electrical parameters are also provided.

Rational harmonic mode-locking pulse quality of the dark-optical-comb injected semiconductor optical amplifier fiber ring laser.

PubMed

Lin, Gong-Ru; Lee, Chao-Kuei; Kang, Jung-Jui

2008-06-09

We study the rational harmonic mode-locking (RHML) order dependent pulse shortening force and dynamic chirp characteristics of a gain-saturated semiconductor optical amplifier fiber laser (SOAFL) under dark-optical-comb injection, and discuss the competition between mode-locking mechanisms in the SOAFL at high-gain and strong optical injection condition at higher RHML orders. The evolutions of spectra, mode-locking and continuous lasing powers by measuring the ratio of DC/pulse amplitude and the pulse shortening force (I(pulse)/P(avg)(2) ) are performed to determine the RHML capability of SOAFL. As the rational harmonic order increases up to 20, the spectral linewidth shrinks from 12 to 3 nm, the ratio of DC/pulse amplitude enlarges from 0.025 to 2.4, and the pulse-shortening force reduces from 0.9 to 0.05. At fundamental and highest RHML condition, we characterize the frequency detuning range to realize the mode-locking quality, and measure the dynamic frequency chirp of the RHML-SOAFL to distinguish the linear and nonlinear chirp after dispersion compensation. With increasing RHML order, the pulsewidth is broadened from 4.2 to 26.4 ps with corresponding chirp reducing from 0.7 to 0.2 GHz and linear/nonlinear chirp ratio changes from 4.3 to 1.3, which interprets the high-order chirp becomes dominates at higher RHML orders.

Economic constraint and modes of consumption of addictive goods.

PubMed

Ben Lakhdar, Christian; Bastianic, Tanja

2011-09-01

To see how economic recession, or, more generally, how increased economic constraint amongst drug users may impact their behaviour regarding the mode of drug consumption. The theoretical framework is the theory of rational addiction - drug users are considered to be rational and well-informed about the way they use drugs and the consequences of using them. Surveys in the specialist literature dealing with the potential changes in the economic context of drugs users, and with the mechanisms of the bioavailability of psychoactive substances are examined in order to highlight one of the strategies drug users can implement to circumvent economic problems - namely a change in the mode of administration. An examination of ethnographic studies and French data are also used to test our assumptions. Changes in the mode of drug consumption can be the result of a maximization behaviour. Injection is the most effective way to reach a maximum bioavailability of substances. There is evidence in favour of the hypothesis that in times of economic recession, when the economic resources of drug users can decrease, they may prefer injection to other modes of administration in order to maximize the effect of what they have purchased. In times of economic recession, harm reduction policy has to be reinforced as injection behaviour can increase. As a result, economic and social policies should be an integral consideration for health policy issues. Copyright © 2011 Elsevier B.V. All rights reserved.

Femtosecond wavelength tunable semiconductor optical amplifier fiber laser mode-locked by backward dark-optical-comb injection at 10 GHz.

PubMed

Lin, Gong-Ru; Chiu, I-Hsiang

2005-10-31

Femtosecond nonlinear pulse compression of a wavelength-tunable, backward dark-optical-comb injection harmonic-mode-locked semiconductor optical amplifier based fiber laser (SOAFL) is demonstrated for the first time. Shortest mode-locked SOAFL pulsewidth of 15 ps at 1 GHz is generated, which can further be compressed to 180 fs after linear chirp compensation, nonlinear soliton compression, and birefringent filtering. A maximum pulsewidth compression ratio for the compressed eighth-order SOAFL soliton of up to 80 is reported. The pedestal-free eighth-order soliton can be obtained by injecting the amplified pulse with peak power of 51 W into a 107.5m-long single-mode fiber (SMF), providing a linewidth and time-bandwidth product of 13.8 nm and 0.31, respectively. The tolerance in SMF length is relatively large (100-300 m) for obtaining <200fs SOAFL pulsewidth at wavelength tuning range of 1530-1560 nm. By extending the repetition frequency of dark-optical-comb up to 10 GHz, the mode-locked SOAFL pulsewidth can be slightly shortened from 5.4 ps to 3.9 ps after dispersion compensating, and further to 560 fs after second-order soliton compression. The lasing linewidth, time-bandwidth product and pulsewidth suppressing ratio of the SOAFL soliton become 4.5 nm, 0.33, and 10, respectively.

Narrow-band injection seeding of a terahertz frequency quantum cascade laser: Selection and suppression of longitudinal modes

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

Nong, Hanond, E-mail: Nong.Hanond@rub.de; Markmann, Sergej; Hekmat, Negar

2014-09-15

A periodically poled lithium niobate (PPLN) crystal with multiple poling periods is used to generate tunable narrow-bandwidth THz pulses for injection seeding a quantum cascade laser (QCL). We demonstrate that longitudinal modes of the quantum cascade laser close to the gain maximum can be selected or suppressed according to the seed spectrum. The QCL emission spectra obtained by electro-optic sampling from the quantum cascade laser, in the most favorable case, shows high selectivity and amplification of the longitudinal modes that overlap the frequency of the narrow-band seed. Proper selection of the narrow-band THz seed from the PPLN crystal discretely tunesmore » the longitudinal mode emission of the quantum cascade laser. Moreover, the THz wave build-up within the laser cavity is studied as a function of the round-trip time. When the seed frequency is outside the maximum of the gain spectrum the laser emission shifts to the preferential longitudinal mode.« less

Fishbone activity in experimental advanced superconducting tokamak neutral beam injection plasma

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

Xu, Liqing; Zhang, Jizong; Chen, Kaiyun, E-mail: Kychen@ipp.cas.cn, E-mail: lqhu@ipp.cas.cn

2015-12-15

Repetitive fishbones near the trapped ion procession frequency were observed for the first time in the neutral beam injection high confinement plasmas in Experimental Advanced Superconducting Tokamak (EAST) tokamak, and diagnosed using a solid-state neutral particle analyzer based on a compact silicon photodiode together with an upgraded high spatial-temporal-resolution multi-arrays soft X-ray (SX) system. This 1/1 typical internal kink mode propagates in the ion-diamagnetism direction with a rotation speed faster than the bulk plasma in the plasma frame. From the SX measurements, this mode frequency is typical of chirping down and the energetic particle effect related to the twisting modemore » structure. This ion fishbone was found able to trigger a multiple core sawtooth crashes with edge-2/1 sideband modes, as well as to lead to a transition from fishbone to long lived saturated kink mode to fishbone. Furthermore, using SX tomography, a correlation between mode amplitude and mode frequency was found. Finally, a phenomenological prey–predator model was found to reproduce the fishbone nonlinear process well.« less

New drostanolone metabolites in human urine by liquid chromatography time-of-flight tandem mass spectrometry and their application for doping control.

PubMed

Liu, Yang; Lu, Jianghai; Yang, Sheng; Zhang, Qingying; Xu, Youxuan

2016-04-01

Drostanolone is one of the most frequently detected anabolic androgenic steroids in doping control analysis. Here, we studied drostanolone urinary metabolic profiles using liquid chromatography quadruple time of flight mass spectrometry (LC-QTOF-MS) in full scan and targeted MS/MS modes with accurate mass measurement. The drug was administered to one healthy male volunteer and liquid-liquid extraction along with direct-injection were used to analyze urine samples. Chromatographic peaks for potential metabolites were identified with the theoretical [M-H](-) as a target ion in a full scan experiment and actual deprotonated ions were analyzed in targeted MS/MS mode. Eleven metabolites including five new sulfates, five glucuronide conjugates, and one free metabolite were confirmed for drostanolone. Due to the absence of useful fragment ions to illustrate the steroid ring structure of drostanolone phase II metabolites, gas chromatography mass spectrometry (GC-MS) was used to obtain structural details of the trimethylsilylated phase I metabolite released after enzymatic hydrolysis and a potential structure was proposed using a combined MS approach. Metabolite detection times were recorded and S4 (2α-methyl-5α-androstan-17-one-6β-ol-3α-sulfate) and G1 (2α-methyl-5α-androstan-17-one-3α-glucuronide) were thought to be new potential biomarkers for drostanolone misuse which can be detected up to 24days by liquid-liquid extraction and 7days by direct-injection analysis after intramuscular injection. S4 and G1 were also detected in two drostanolone-positive routine urine samples. Copyright © 2016 Elsevier Inc. All rights reserved.

Direct characterization of aqueous extract of Hibiscus sabdariffa using HPLC with diode array detection coupled to ESI and ion trap MS.

PubMed

Rodríguez-Medina, Inmaculada C; Beltrán-Debón, Raúl; Molina, Vicente Micol; Alonso-Villaverde, Carlos; Joven, Jorge; Menéndez, Javier A; Segura-Carretero, Antonio; Fernández-Gutiérrez, Alberto

2009-10-01

The phenolic fraction and other polar compounds of the Hibiscus sabdariffa were separated and identified by HPLC with diode array detection coupled to electrospray TOF and IT tandem MS (DAD-HPLC-ESI-TOF-MS and IT-MS). The H. sabdariffa aqueous extract was filtered and directly injected into the LC system. The analysis of the compounds was carried out by RP HPLC coupled to DAD and TOF-MS in order to obtain molecular formula and exact mass. Posterior analyses with IT-MS were performed and the fragmentation pattern and confirmation of the structures were achieved. The H. sabdariffa samples were successfully analyzed in positive and negative ionization modes with two optimized linear gradients. In positive mode, the two most representative anthocyanins and other compounds were identified whereas the phenolic fraction, hydroxycitric acid and its lactone were identified using the negative ionization mode.

Numerical Design of Megawatt Gyrotron with 120 GHz Frequency and 50% Efficiency for Plasma Fusion Application

NASA Astrophysics Data System (ADS)

Kumar, Nitin; Singh, Udaybir; Kumar, Anil; Bhattacharya, Ranajoy; Singh, T. P.; Sinha, A. K.

2013-02-01

The design of 120 GHz, 1 MW gyrotron for plasma fusion application is presented in this paper. The mode selection is carried out considering the aim of minimum mode competition, minimum cavity wall heating, etc. On the basis of the selected operating mode, the interaction cavity design and beam-wave interaction computation are carried out by using the PIC code. The design of triode type Magnetron Injection Gun (MIG) is also presented. Trajectory code EGUN, synthesis code MIGSYN and data analysis code MIGANS are used in the MIG designing. Further, the design of MIG is also validated by using the another trajectory code TRAK. The design results of beam dumping system (collector) and RF window are also presented. Depressed collector is designed to enhance the overall tube efficiency. The design study confirms >1 MW output power with tube efficiency around 50% (with collector efficiency).

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

Pierre, John W.; Wies, Richard; Trudnowski, Daniel

Time-synchronized measurements provide rich information for estimating a power-system's electromechanical modal properties via advanced signal processing. This information is becoming critical for the improved operational reliability of interconnected grids. A given mode's properties are described by its frequency, damping, and shape. Modal frequencies and damping are useful indicators of power-system stress, usually declining with increased load or reduced grid capacity. Mode shape provides critical information for operational control actions. This project investigated many advanced techniques for power system identification from measured data focusing on mode frequency and damping ratio estimation. Investigators from the three universities coordinated their effort with Pacificmore » Northwest National Laboratory (PNNL). Significant progress was made on developing appropriate techniques for system identification with confidence intervals and testing those techniques on field measured data and through simulation. Experimental data from the western area power system was provided by PNNL and Bonneville Power Administration (BPA) for both ambient conditions and for signal injection tests. Three large-scale tests were conducted for the western area in 2005 and 2006. Measured field PMU (Phasor Measurement Unit) data was provided to the three universities. A 19-machine simulation model was enhanced for testing the system identification algorithms. Extensive simulations were run with this model to test the performance of the algorithms. University of Wyoming researchers participated in four primary activities: (1) Block and adaptive processing techniques for mode estimation from ambient signals and probing signals, (2) confidence interval estimation, (3) probing signal design and injection method analysis, and (4) performance assessment and validation from simulated and field measured data. Subspace based methods have been use to improve previous results from block processing techniques. Bootstrap techniques have been developed to estimate confidence intervals for the electromechanical modes from field measured data. Results were obtained using injected signal data provided by BPA. A new probing signal was designed that puts more strength into the signal for a given maximum peak to peak swing. Further simulations were conducted on a model based on measured data and with the modifications of the 19-machine simulation model. Montana Tech researchers participated in two primary activities: (1) continued development of the 19-machine simulation test system to include a DC line; and (2) extensive simulation analysis of the various system identification algorithms and bootstrap techniques using the 19 machine model. Researchers at the University of Alaska-Fairbanks focused on the development and testing of adaptive filter algorithms for mode estimation using data generated from simulation models and on data provided in collaboration with BPA and PNNL. There efforts consist of pre-processing field data, testing and refining adaptive filter techniques (specifically the Least Mean Squares (LMS), the Adaptive Step-size LMS (ASLMS), and Error Tracking (ET) algorithms). They also improved convergence of the adaptive algorithms by using an initial estimate from block processing AR method to initialize the weight vector for LMS. Extensive testing was performed on simulated data from the 19 machine model. This project was also extensively involved in the WECC (Western Electricity Coordinating Council) system wide tests carried out in 2005 and 2006. These tests involved injecting known probing signals into the western power grid. One of the primary goals of these tests was the reliable estimation of electromechanical mode properties from measured PMU data. Applied to the system were three types of probing inputs: (1) activation of the Chief Joseph Dynamic Brake, (2) mid-level probing at the Pacific DC Intertie (PDCI), and (3) low-level probing on the PDCI. The Chief Joseph Dynamic Brake is a 1400 MW disturbance to the system and is injected for a half of a second. For the mid and low-level probing, the Celilo terminal of the PDCI is modulated with a known probing signal. Similar but less extensive tests were conducted in June of 2000. The low-level probing signals were designed at the University of Wyoming. A number of important design factors are considered. The designed low-level probing signal used in the tests is a multi-sine signal. Its frequency content is focused in the range of the inter-area electromechanical modes. The most frequently used of these low-level multi-sine signals had a period of over two minutes, a root-mean-square (rms) value of 14 MW, and a peak magnitude of 20 MW. Up to 15 cycles of this probing signal were injected into the system resulting in a processing gain of 15. The resulting measured response at points throughout the system was not much larger than the ambient noise present in the measurements.« less

Effects of concentrated leachate injection modes on stabilization of landfilled waste.

PubMed

He, Ruo; Wei, Xiao-Meng; Chen, Min; Su, Yao; Tian, Bao-Hu

2016-02-01

Injection of concentrated leachate to landfills is a simple and cost-effective technology for concentrated leachate treatment. In this study, the effects of injection mode of concentrated leachate and its hydraulic loading rate on the stabilization of landfilled waste were investigated. Compared with the injection of concentrated leachate, the joint injection of leachate and concentrated leachate (1:1, v/v) was more beneficial to the degradation of landfilled waste and mitigated the discharge amount of pollutants at the hydraulic loading rate of 5.9 L m(-2) day(-1). As the hydraulic loading rate of the joint injection of leachate and concentrated leachate was increased from 5.9 to 17.6 L m(-2) day(-1), the organic matter, biologically degradable matter, and total nitrogen of landfilled waste were degraded more rapidly, with the degradation constant of the first-order kinetics of 0.005, 0.004, and 0.003, respectively. Additionally, NO2(-)-N and NO3(-)-N in the concentrated leachate could be well removed in the landfill bioreactors. These results showed that a joint injection of concentrated leachate and raw leachate might be a good way to relieve the inhibitory effect of high concentrations of toxic pollutants in the concentrated leachate and accelerate the stabilization of landfilled waste.

CARL: a LabVIEW 3 computer program for conducting exposure therapy for the treatment of dental injection fear.

PubMed

Coldwell, S E; Getz, T; Milgrom, P; Prall, C W; Spadafora, A; Ramsay, D S

1998-04-01

This paper describes CARL (Computer Assisted Relaxation Learning), a computerized, exposure-based therapy program for the treatment of dental injection fear. The CARL program operates primarily in two different modes; in vitro, which presents a video-taped exposure hierarchy, and in vivo, which presents scripts for a dentist or hygienist to use while working with a subject. Two additional modes are used to train subjects to use the program and to administer behavioral assessment tests. The program contains five different modules, which function to register a subject, train subjects to use physical and cognitive relaxation techniques, deliver an exposure hierarchy, question subjects about the helpfulness of each of the therapy components, and test for memory effects of anxiolytic medication. Nine subjects have completed the CARL therapy program and 1-yr follow-up as participants in a placebo-controlled clinical trial examining the effects of alprazolam on exposure therapy for dental injection phobia. All nine subjects were able to receive two dental injections, and all reduced their general fear of dental injections. Initial results therefore indicate that the CARL program successfully reduces dental injection fear.

Electron kinetics in capacitively coupled plasmas modulated by electron injection

NASA Astrophysics Data System (ADS)

Zhang, Ya; Peng, Yanli; Innocenti, Maria Elena; Jiang, Wei; Wang, Hong-yu; Lapenta, Giovanni

2017-09-01

The controlling effect of an electron injection on the electron energy distribution function (EEDF) and on the energetic electron flux, in a capacitive radio-frequency argon plasma, is studied using a one-dimensional particle-in-cell/Monte Carlo collisions model. The input power of the electron beam is as small as several tens of Watts with laboratory achievable emission currents and energies. With the electron injection, the electron temperature decreases but with a significant high energy tail. The electron density, electron temperature in the sheath, and electron heating rate increase with the increasing emission energy. This is attributed to the extra heating of the energetic electrons in the EEDF tail. The non-equilibrium EEDF is obtained for strong non-local distributions of the electric field, electron heating rate, excitation, and ionization rate, indicating the discharge has transited from a volume heating (α-mode dominated) into a sheath heating (γ-mode dominated) type. In addition, the electron injection not only modifies the self-bias voltage, but also enhances the electron flux that can reach the electrodes. Moreover, the relative population of energetic electrons significantly increases with the electron injection compared to that without the electron injection, relevant for modifying the gas and surface chemistry reactions.

Electrically-pumped, broad-area, single-mode photonic crystal lasers.

PubMed

Zhu, Lin; Chak, Philip; Poon, Joyce K S; DeRose, Guy A; Yariv, Amnon; Scherer, Axel

2007-05-14

Planar broad-area single-mode lasers, with modal widths of the order of tens of microns, are technologically important for high-power applications and improved coupling efficiency into optical fibers. They may also find new areas of applications in on-chip integration with devices that are of similar size scales, such as for spectroscopy in microfluidic chambers or optical signal processing with micro-electromechanical systems. An outstanding challenge is that broad-area lasers often require external means of control, such as injection-locking or a frequency/spatial filter to obtain single-mode operation. In this paper, we propose and demonstrate effective index-guided, large-area, edge-emitting photonic crystal lasers driven by pulsed electrical current injection at the optical telecommunication wavelength of 1550 nm. By suitable design of the photonic crystal lattice, our lasers operate in a single mode with a 1/e(2) modal width of 25 microm and a length of 600 microm.

First Results of ELM Triggering With a Multichamber Lithium Granule Injector Into EAST Discharges

DOE PAGES

Sun, Z.; Lunsford, R.; Maingi, R.; ...

2017-12-12

A critical challenge facing the basic long-pulse H-mode for ITER is to control edge-localized modes (ELMs). A new method using a multichamber lithium (Li) granule injector (LGI) for ELM triggering experiments has been developed in Experimental Advanced Superconducting Tokamak (EAST). First experimental results of the control of ELMs are obtained in EAST with a tungsten divertor. It is found that the injector has good capacities, i.e., allowing good flexibilities in granule size selection, injection rate, and injection velocity. In conclusion, LGI has successfully triggered ELMs during the H-mode. These results indicate the LGI would be a promising method to controlmore » ELMs in long-pulse steady-state tokamaks.« less

First Results of ELM Triggering With a Multichamber Lithium Granule Injector Into EAST Discharges

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

Sun, Z.; Lunsford, R.; Maingi, R.

A critical challenge facing the basic long-pulse H-mode for ITER is to control edge-localized modes (ELMs). A new method using a multichamber lithium (Li) granule injector (LGI) for ELM triggering experiments has been developed in Experimental Advanced Superconducting Tokamak (EAST). First experimental results of the control of ELMs are obtained in EAST with a tungsten divertor. It is found that the injector has good capacities, i.e., allowing good flexibilities in granule size selection, injection rate, and injection velocity. In conclusion, LGI has successfully triggered ELMs during the H-mode. These results indicate the LGI would be a promising method to controlmore » ELMs in long-pulse steady-state tokamaks.« less

Controlled Asymmetry of Einstein-Podolsky-Rosen Steering with an Injected Nondegenerate Optical Parametric Oscillator

NASA Astrophysics Data System (ADS)

Olsen, M. K.

2017-10-01

We propose and analyze a nonlinear optical apparatus in which the direction of asymmetric steering is controllable within the apparatus, rather than by adding noise to measurements. Using a nondegenerate parametric oscillator with an injected signal field, we show how the directionality and extent of the steering can be readily controlled for output modes that can be up to one octave apart. The two down-converted modes, which exhibit the greater violations of the steering inequalities, can also be controlled to exhibit asymmetric steering in some regimes.

Orbit-based analysis of nonlinear energetic ion dynamics in tokamaks. II. Mechanisms for rapid chirping and convective amplification

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

Bierwage, Andreas; Shinohara, Kouji

2016-04-15

The nonlinear interactions between shear Alfvén modes and tangentially injected beam ions in the 150–400 keV range are studied numerically in realistic geometry for a JT-60U tokamak scenario. In Paper I, which was reported in the companion paper, the recently developed orbit-based resonance analysis method was used to track the resonant frequency of fast ions during their nonlinear evolution subject to large magnetic and electric drifts. Here, that method is applied to map the wave-particle power transfer from the canonical guiding center phase space into the frequency-radius plane, where it can be directly compared with the evolution of the fluctuation spectramore » of fast-ion-driven modes. Using this technique, we study the nonlinear dynamics of strongly driven shear Alfvén modes with low toroidal mode numbers n = 1 and n = 3. In the n = 3 case, both chirping and convective amplification can be attributed to the mode following the resonant frequency of the radially displaced particles, i.e., the usual one-dimensional phase locking process. In the n = 1 case, a new chirping mechanism is found, which involves multiple dimensions, namely, wave-particle trapping in the radial direction and phase mixing across velocity coordinates.« less

Heat performance resulting from combined effects of radiation and mixed convection in a rectangular cavity ventilated by injection or suction

NASA Astrophysics Data System (ADS)

Ezzaraa, K.; Bahlaoui, A.; Arroub, I.; Raji, A.; Hasnaoui, M.; Naïmi, M.

2018-05-01

In this work, we investigated numerically heat transfer by mixed convection coupled to thermal radiation in a vented rectangular enclosure uniformly heated from below with a constant heat flux. The fresh fluid is admitted into the cavity by injection or suction, by means of two openings located on the lower part of both right and left vertical sides. Another opening is placed on the middle of the top wall to ensure the ventilation. Air, a radiatively transparent medium, is considered to be the cooling fluid. The inner surfaces, in contact with the fluid, are assumed to be gray, diffuse emitters and reflectors of radiation with identical emissivities. The effects of some pertinent parameters such as the Reynolds number, 300 ≤ Re ≤ 5000, and the emissivity of the walls, 0 ≤ ɛ ≤ 0.85, on flow and temperature patterns as well as on the heat transfer rate within the enclosure are presented for the two ventilation modes (injection and suction). The results indicate that the flow and thermal structures are affected by the thermal radiation for the two modes of imposed flow. However, the suction mode is found to be more favorable to the heat transfer in comparison with the injection one.

Fast batch injection analysis of H(2)O(2) using an array of Pt-modified gold microelectrodes obtained from split electronic chips.

PubMed

Pacheco, Bruno D; Valério, Jaqueline; Angnes, Lúcio; Pedrotti, Jairo J

2011-06-24

A fast and robust analytical method for amperometric determination of hydrogen peroxide (H(2)O(2)) based on batch injection analysis (BIA) on an array of gold microelectrodes modified with platinum is proposed. The gold microelectrode array (n=14) was obtained from electronic chips developed for surface mounted device technology (SMD), whose size offers advantages to adapt them in batch cells. The effect of the dispensing rate, volume injected, distance between the platinum microelectrodes and the pipette tip, as well as the volume of solution in the cell on the analytical response were evaluated. The method allows the H(2)O(2) amperometric determination in the concentration range from 0.8 μmolL(-1) to 100 μmolL(-1). The analytical frequency can attain 300 determinations per hour and the detection limit was estimated in 0.34 μmolL(-1) (3σ). The anodic current peaks obtained after a series of 23 successive injections of 50 μL of 25 μmolL(-1) H(2)O(2) showed an RSD<0.9%. To ensure the good selectivity to detect H(2)O(2), its determination was performed in a differential mode, with selective destruction of the H(2)O(2) with catalase in 10 mmolL(-1) phosphate buffer solution. Practical application of the analytical procedure involved H(2)O(2) determination in rainwater of São Paulo City. A comparison of the results obtained by the proposed amperometric method with another one which combines flow injection analysis (FIA) with spectrophotometric detection showed good agreement. Copyright © 2011 Elsevier B.V. All rights reserved.

Human Mars Mission: Launch Window from Earth Orbit. Pt. 1

NASA Technical Reports Server (NTRS)

Young, Archie

1999-01-01

The determination of orbital window characteristics is of major importance in the analysis of human interplanetary missions and systems. The orbital launch window characteristics are directly involved in the selection of mission trajectories, the development of orbit operational concepts, and the design of orbital launch systems. The orbital launch window problem arises because of the dynamic nature of the relative geometry between outgoing (departure) asymptote of the hyperbolic escape trajectory and the earth parking orbit. The orientation of the escape hyperbola asymptotic relative to earth is a function of time. The required hyperbola energy level also varies with time. In addition, the inertial orientation of the parking orbit is a function of time because of the perturbations caused by the Earth's oblateness. Thus, a coplanar injection onto the escape hyperbola can be made only at a point in time when the outgoing escape asymptote is contained by the plane of parking orbit. Even though this condition may be planned as a nominal situation, it will not generally represent the more probable injection geometry. The general case of an escape injection maneuver performed at a time other than the coplanar time will involve both a path angle and plane change and, therefore, a DELTA V penalty. Usually, because of the DELTA V penalty the actual departure injection window is smaller in duration than that determined by energy requirement alone. This report contains the formulation, characteristics, and test cases for five different launch window modes for Earth orbit. These modes are: (1) One impulsive maneuver from a Highly Elliptical Orbit (HEO) (2) Two impulsive maneuvers from a Highly Elliptical Orbit (HEO) (3) One impulsive maneuver from a Low Earth Orbit (LEO) (4) Two impulsive maneuvers from LEO (5) Three impulsive maneuvers from LEO.

Comparison of Friction Characteristics on TN and VA Mode Alignment Films with Friction Force Microscopy

NASA Astrophysics Data System (ADS)

Kwak, Musun; Chung, Hanrok; Kwon, Hyukmin; Kim, Jehyun; Han, Daekyung; Yi, Yoonseon; Lee, Sangmun; Lee, Chulgu; Cha, Sooyoul

Using frictional force microscopy (FFM), the friction surface characteristics were compared between twisted nematic (TN) mode and vertical alignment (VA) mode alignment films (AFs). The friction asymmetry was detected depending on temperature conditions on TN mode AF, but not on VA mode AF. The difference between two modes was explained by leaning intermolecular repulsion caused by the pre-tilt angle uniformity and the density of side chain. No level difference according to temperature conditions appeared when the pre-tilt angle were measured after liquid crystal (LC) injection.

Impurity mixing and radiation asymmetry in massive gas injection simulations of DIII-D

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

Izzo, V. A.

Simulations of neon massive gas injection into DIII-D are performed with the 3D MHD code NIMROD. The poloidal and toroidal distribution of the impurity source is varied. This report will focus on the effects of the source variation on impurity mixing and radiated power asymmetry. Even toroidally symmetric impurity injection is found to produce asymmetric radiated power due to asymmetric convective heat flux produced by the 1/1 mode. When the gas source is toroidally localized, the phase relationship between the mode and the source location is important, affecting both radiation peaking and impurity mixing. Under certain circumstances, a single, localizedmore » gas jet could produce better radiation symmetry during the disruption thermal quench than evenly distributed impurities.« less

Multimode Silicon Nanowire Transistors

PubMed Central

2014-01-01

The combined capabilities of both a nonplanar design and nonconventional carrier injection mechanisms are subject to recent scientific investigations to overcome the limitations of silicon metal oxide semiconductor field effect transistors. In this Letter, we present a multimode field effect transistors device using silicon nanowires that feature an axial n-type/intrinsic doping junction. A heterostructural device design is achieved by employing a self-aligned nickel-silicide source contact. The polymorph operation of the dual-gate device enabling the configuration of one p- and two n-type transistor modes is demonstrated. Not only the type but also the carrier injection mode can be altered by appropriate biasing of the two gate terminals or by inverting the drain bias. With a combined band-to-band and Schottky tunneling mechanism, in p-type mode a subthreshold swing as low as 143 mV/dec and an ON/OFF ratio of up to 104 is found. As the device operates in forward bias, a nonconventional tunneling transistor is realized, enabling an effective suppression of ambipolarity. Depending on the drain bias, two different n-type modes are distinguishable. The carrier injection is dominated by thermionic emission in forward bias with a maximum ON/OFF ratio of up to 107 whereas in reverse bias a Schottky tunneling mechanism dominates the carrier transport. PMID:25303290

Characteristics of dioxin emissions from a Waelz plant with acid and basic kiln mode.

PubMed

Hung, Pao Chen; Chi, Kai Hsien; Chen, Mei Lien; Chang, Moo Been

2012-01-30

The concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were measured in the flue gas of a Waelz plant operated in acid and basic modes, respectively. To abate (PCDD/F) and other pollutants, the plant operates with a post-treatment of flue gases by activated carbon injection and subsequent filtration. Relatively high PCDD/F discharge by fly ashes is found with acid kiln mode of the Waelz process. Therefore, basic kiln mode of the Waelz process is investigated and compared in this plant. With the adsorbent injection rate of 7 kg/h (95 mg/Nm(3)), the PCDD/F concentration in stack gas was measured as 0.123 ng I-TEQ/Nm(3) in the basic operating mode. The added Ca(OH)(2) reacted with metal catalysts and HCl((g)) in the flue gas and thus effectively suppressed the formation of PCDD/Fs. PCDD/F concentrations in fly ashes sampled from the dust settling chamber, cyclone, primary filter and secondary filter in basic kiln mode were significantly lower than that in acid kiln mode. Total PCDD/F emission on the basis of treating one kg of electric arc furnace dust in the basic operation mode was 269 ng I-TEQ/kg EAF-dust treated which was significantly lower than that in acid mode (640 ng I-TEQ/kg EAF-dust treated). Copyright © 2011 Elsevier B.V. All rights reserved.

Maternal and infant characteristics by mode of vitamin K prophylaxis administration.

PubMed

Khambalia, Amina Z; Roberts, Christine L; Bowen, Jennifer R; Nassar, Natasha

2012-08-01

  The aim of this study was to compare maternal and infant characteristics by mode of VK administration.   De-identified computerised birth files of all babies born in New South Wales (NSW), Australia between January 2007 and December 2009 (when VK prophylaxis was measured) were included in the present study. The outcome variable, mode of VK prophylaxis, was recorded by checkbox as oral, IM injection, none or not stated.   We analysed population-based birth data from 2007 to 2009 in NSW, Australia and found that IM injection was the most prevalent mode of administration (96.3%, n = 263, 555), followed by oral (2.6%, n = 7023) and none (1.2%, n = 3136). Compared to neonates receiving IM VK, those with oral or none were more likely to have vaginal births without medical interventions at birth centres or planned home births and were less likely to receive hepatitis B vaccination. Among neonates administered oral VK, a larger proportion were preterm births and breastfed at discharge compared to neonates administered VK as an IM injection. Neonates with no VK recorded were more likely to be admitted to neonatal intensive care, but may have received VK later in the birth admission.   A small proportion of the Australian neonates may be at risk of inadequate protection from VKBD due to parental concerns about the safety of IM injection of VK to neonates. © 2012 The Authors. Journal of Paediatrics and Child Health © 2012 Paediatrics and Child Health Division (Royal Australasian College of Physicians).

Optical microwave interactions in semiconductor devices

NASA Astrophysics Data System (ADS)

Figueroa, L.; Slayman, C. W.; Yen, H. W.

1980-11-01

The results of an extensive characterization of high speed analog modulation of (GaAl)As injection lasers, high speed optical detectors, and mode locking of (GaAl)As injection lasers are presented. Commercial injection lasers were successfully modulated up to 5 GHz. The 5 GHz value represents a practical upper limit to the modulation bandwith of existing commercial lasers. The laser equivalent circuit was characterized and the parasitics were found to play a significant role in the high speed modulation of the injection laser.

Combustion Stability Analyses of Coaxial Element Injectors with Liquid Oxygen/Liquid Methane Propellants

NASA Technical Reports Server (NTRS)

Hulka, J. R.

2010-01-01

Liquid rocket engines using oxygen and methane propellants are being considered by the National Aeronautics and Space Administration (NASA) for in-space vehicles. This propellant combination has not been previously used in a flight-qualified engine system, so limited test data and analysis results are available at this stage of early development. NASA has funded several hardware-oriented activities with oxygen and methane propellants over the past several years with the Propulsion and Cryogenic Advanced Development (PCAD) project, under the Exploration Technology Development Program. As part of this effort, the NASA Marshall Space Flight Center has conducted combustion stability analyses of several of the configurations. This paper presents test data and analyses of combustion stability from the recent PCAD-funded test programs at the NASA MSFC. These test programs used swirl coaxial element injectors with liquid oxygen and liquid methane propellants. Oxygen was injected conventionally in the center of the coaxial element, and swirl was provided by tangential entry slots. Injectors with 28-element and 40-element patterns were tested with several configurations of combustion chambers, including ablative and calorimeter spool sections, and several configurations of fuel injection design. Low frequency combustion instability (chug) occurred with both injectors, and high-frequency combustion instability occurred at the first tangential (1T) transverse mode with the 40-element injector. In most tests, a transition between high-amplitude chug with gaseous methane flow and low-amplitude chug with liquid methane flow was readily observed. Chug analyses of both conditions were conducted using techniques from Wenzel and Szuch and from the Rocket Combustor Interactive Design and Analysis (ROCCID) code. The 1T mode instability occurred in several tests and was apparent by high-frequency pressure measurements as well as dramatic increases in calorimeter-measured heat flux throughout the chamber. Analyses of the transverse mode were conducted with ROCCID and empirical methods such as Hewitt d/V. This paper describes the test hardware configurations, test data, analysis methods, and presents results of the various analyses.

Spray characteristics of two combined jet atomizers

NASA Astrophysics Data System (ADS)

Tambour, Y.; Portnoy, D.

The downstream changes in droplet volume concentration of a vaporizing fuel spray produced by two jet atomizers which form an overlapping zone of influence is theoretically analyzed, employing experimental data of Yule et al. (1982) for a single jet atomizer as initial conditions. One of the atomizers is located below the other at a certain distance downstream. Such an injection geometry can be found in afterburners of modern jet engines. The influence of various vertical and horizontal distances between the two atomizers on the downstream spray characteristics is investigated for a vaporizing kerosene spray in a 'cold' (293 K) and a 'hot' (450 K) environment. The analysis shows how one can control the downstream spray characteristics via the geometry of injection. Such geometrical considerations may be of great importance in the design of afterburner wall geometry and in the reduction of wall thermal damage. The injection geometry may also affect the intensity of the spray distribution which determines the mode of droplet group combustion. The latter plays an important role in improving afterburner combustion efficiency.

Observing Exoplanets with High-dispersion Coronagraphy. II. Demonstration of an Active Single-mode Fiber Injection Unit

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

Mawet, D.; Ruane, G.; Xuan, W.

2017-04-01

High-dispersion coronagraphy (HDC) optimally combines high-contrast imaging techniques such as adaptive optics/wavefront control plus coronagraphy to high spectral resolution spectroscopy. HDC is a critical pathway toward fully characterizing exoplanet atmospheres across a broad range of masses from giant gaseous planets down to Earth-like planets. In addition to determining the molecular composition of exoplanet atmospheres, HDC also enables Doppler mapping of atmosphere inhomogeneities (temperature, clouds, wind), as well as precise measurements of exoplanet rotational velocities. Here, we demonstrate an innovative concept for injecting the directly imaged planet light into a single-mode fiber, linking a high-contrast adaptively corrected coronagraph to a high-resolutionmore » spectrograph (diffraction-limited or not). Our laboratory demonstration includes three key milestones: close-to-theoretical injection efficiency, accurate pointing and tracking, and on-fiber coherent modulation and speckle nulling of spurious starlight signal coupling into the fiber. Using the extreme modal selectivity of single-mode fibers, we also demonstrated speckle suppression gains that outperform conventional image-based speckle nulling by at least two orders of magnitude.« less

Observing Exoplanets with High-dispersion Coronagraphy. II. Demonstration of an Active Single-mode Fiber Injection Unit

NASA Astrophysics Data System (ADS)

Mawet, D.; Ruane, G.; Xuan, W.; Echeverri, D.; Klimovich, N.; Randolph, M.; Fucik, J.; Wallace, J. K.; Wang, J.; Vasisht, G.; Dekany, R.; Mennesson, B.; Choquet, E.; Delorme, J.-R.; Serabyn, E.

2017-04-01

High-dispersion coronagraphy (HDC) optimally combines high-contrast imaging techniques such as adaptive optics/wavefront control plus coronagraphy to high spectral resolution spectroscopy. HDC is a critical pathway toward fully characterizing exoplanet atmospheres across a broad range of masses from giant gaseous planets down to Earth-like planets. In addition to determining the molecular composition of exoplanet atmospheres, HDC also enables Doppler mapping of atmosphere inhomogeneities (temperature, clouds, wind), as well as precise measurements of exoplanet rotational velocities. Here, we demonstrate an innovative concept for injecting the directly imaged planet light into a single-mode fiber, linking a high-contrast adaptively corrected coronagraph to a high-resolution spectrograph (diffraction-limited or not). Our laboratory demonstration includes three key milestones: close-to-theoretical injection efficiency, accurate pointing and tracking, and on-fiber coherent modulation and speckle nulling of spurious starlight signal coupling into the fiber. Using the extreme modal selectivity of single-mode fibers, we also demonstrated speckle suppression gains that outperform conventional image-based speckle nulling by at least two orders of magnitude.

Twenty barrel in situ pipe gun type solid hydrogen pellet injector for the Large Helical Device.

PubMed

Sakamoto, Ryuichi; Motojima, Gen; Hayashi, Hiromi; Inoue, Tomoyuki; Ito, Yasuhiko; Ogawa, Hideki; Takami, Shigeyuki; Yokota, Mitsuhiro; Yamada, Hiroshi

2013-08-01

A 20 barrel solid hydrogen pellet injector, which is able to inject 20 cylindrical pellets with a diameter and length of between 3.0 and 3.8 mm at the velocity of 1200 m/s, has been developed for the purpose of direct core fueling in LHD (Large Helical Device). The in situ pipe gun concept with the use of compact cryo-coolers enables stable operation as a fundamental facility in plasma experiments. The combination of the two types of pellet injection timing control modes, i.e., pre-programing mode and real-time control mode, allows the build-up and sustainment of high density plasma around the density limit. The pellet injector has demonstrated stable operation characteristics during the past three years of LHD experiments.

Coherent radio-frequency detection for narrowband direct comb spectroscopy.

PubMed

Anstie, James D; Perrella, Christopher; Light, Philip S; Luiten, Andre N

2016-02-22

We demonstrate a scheme for coherent narrowband direct optical frequency comb spectroscopy. An extended cavity diode laser is injection locked to a single mode of an optical frequency comb, frequency shifted, and used as a local oscillator to optically down-mix the interrogating comb on a fast photodetector. The high spectral coherence of the injection lock generates a microwave frequency comb at the output of the photodiode with very narrow features, enabling spectral information to be further down-mixed to RF frequencies, allowing optical transmittance and phase to be obtained using electronics commonly found in the lab. We demonstrate two methods for achieving this step: a serial mode-by-mode approach and a parallel dual-comb approach, with the Cs D1 transition at 894 nm as a test case.

Suppression of the Saffman-Taylor instability through injection of a finite slug of polymer

NASA Astrophysics Data System (ADS)

Beeson-Jones, Timothy H.; Woods, Andrew W.

2014-11-01

During secondary oil recovery, relatively mobile water can channel through oil owing to the Saffman-Taylor instability. Injection of a finite slug of polymer solution from a central well prior to the water flood suppresses the growth of the instability by reducing the adverse mobility ratio at the leading interface. A linear stability analysis of an axisymmetric base state identifies how perturbations on the leading and trailing interfaces become coupled. It also reveals the dependence of the long-time algebraic growth of each mode on the mobility ratios across the two interfaces. The viscosity of the polymer solution which minimizes the growth rate of the instability is identified, and the impact of different slug sizes on this growth is described. Funded by EPSRC & BP.

Bulk-modified modified screen-printing carbon electrodes with both lactate oxidase (LOD) and horseradish peroxide (HRP) for the determination of L-lactate in flow injection analysis mode.

PubMed

Ghamouss, Fouad; Ledru, Sophie; Ruillé, Nadine; Lantier, Françoise; Boujtita, Mohammed

2006-06-16

A screen-printed carbon electrode modified with both HRP and LOD (SPCE-HRP/LOD) has been developed for the determination of L-lactate concentration in real samples. The resulting SPCE-HRP/LOD was prepared in a one-step procedure, and was then optimised as an amperometric biosensor operating at [0, -100]mV versus Ag/AgCl for L-lactate determination in flow injection mode. A significant improvement in the reproducibility (coefficient variation of about 10%) of the preparation of the biosensors was obtained when graphite powder was modified with LOD in the presence of HRP previously oxidised by periodate ion (IO4-). Optimisation studies were performed by examining the effects of LOD loading, periodation step and rate of the binder on analytical performances of SPCE-HRP/LOD. The sensitivity of the optimised SPCE-HRP/LOD to L-lactate was 0.84 nAL micromol(-1) in a detection range between 10 and 180 microMol. The possibility of using the developed biosensor to determine L-lactate concentrations in various dairy products was also evaluated.

Influences of Detection Pinhole and Sample Flow on Thermal Lens Detection in Microfluidic Systems

NASA Astrophysics Data System (ADS)

Liu, Mingqiang; Franko, Mladen

2014-12-01

Thermal lens microscopy (TLM), due to its high temporal () and spatial resolution (), has been coupled to lab-on-chip chemistry for detection of a variety of compounds in chemical or biological fields. Due to the very short optical path length (usually below 100 ) in a microchip, the sensitivity of TLM is unfortunately still 10 to 100 times lower than conventional TLS with 1 cm sample length. Optimization of the TLM optical configuration was made with respect to different pinhole aperture-to-beam size ratios for the best signal-to-noise ratio. In the static mode, the instrumental noise comes mainly from the shot noise of the probe beam when the chopper frequency is over 1 kHz or from the flicker noise of the probe beam at low frequencies. In the flowing mode, the flow-induced noise becomes dominant when the flow rate is high. At a given flow rate, fluids with a higher density and/or a higher viscosity will cause larger flow-induced noise. As an application, a combined microfluidic flow injection analysis ()-TLM device was developed for rapid determination of pollutants by colorimetric reactions. Hexavalent chromium [Cr(VI)] was measured as a model analyte. Analytical signals for 12 sample injections in 1 min have been recorded by the FIA-TLM. For injections of sub-L samples into the microfluidic stream in a deep microchannel, a limit of detection of was achieved for Cr(VI) in water at 60 mW excitation power.

Chemical Profiling of Re-Du-Ning Injection by Ultra-Performance Liquid Chromatography Coupled with Electrospray Ionization Tandem Quadrupole Time-of-Flight Mass Spectrometry through the Screening of Diagnostic Ions in MSE Mode

PubMed Central

Wang, Zhenzhong; Geng, Jianliang; Dai, Yi; Xiao, Wei; Yao, Xinsheng

2015-01-01

The broad applications and mechanism explorations of traditional Chinese medicine prescriptions (TCMPs) require a clear understanding of TCMP chemical constituents. In the present study, we describe an efficient and universally applicable analytical approach based on ultra-performance liquid chromatography coupled to electrospray ionization tandem quadrupole time-of-flight mass spectrometry (UPLC-ESI-Q/TOF-MS) with the MSE (E denotes collision energy) data acquisition mode, which allowed the rapid separation and reliable determination of TCMP chemical constituents. By monitoring diagnostic ions in the high energy function of MSE, target peaks of analogous compounds in TCMPs could be rapidly screened and identified. “Re-Du-Ning” injection (RDN), a eutherapeutic traditional Chinese medicine injection (TCMI) that has been widely used to reduce fever caused by viral infections in clinical practice, was studied as an example. In total, 90 compounds, including five new iridoids and one new sesquiterpene, were identified or tentatively characterized by accurate mass measurements within 5 ppm error. This analysis was accompanied by MS fragmentation and reference standard comparison analyses. Furthermore, the herbal sources of these compounds were unambiguously confirmed by comparing the extracted ion chromatograms (EICs) of RDN and ingredient herbal extracts. Our work provides a certain foundation for further studies of RDN. Moreover, the analytical approach developed herein has proven to be generally applicable for profiling the chemical constituents in TCMPs and other complicated mixtures. PMID:25875968

Calculating electron cyclotron current drive stabilization of resistive tearing modes in a nonlinear magnetohydrodynamic model

NASA Astrophysics Data System (ADS)

Jenkins, Thomas G.; Kruger, Scott E.; Hegna, C. C.; Schnack, Dalton D.; Sovinec, Carl R.

2010-01-01

A model which incorporates the effects of electron cyclotron current drive (ECCD) into the magnetohydrodynamic equations is implemented in the NIMROD code [C. R. Sovinec et al., J. Comput. Phys. 195, 355 (2004)] and used to investigate the effect of ECCD injection on the stability, growth, and dynamical behavior of magnetic islands associated with resistive tearing modes. In addition to qualitatively and quantitatively agreeing with numerical results obtained from the inclusion of localized ECCD deposition in static equilibrium solvers [A. Pletzer and F. W. Perkins, Phys. Plasmas 6, 1589 (1999)], predictions from the model further elaborate the role which rational surface motion plays in these results. The complete suppression of the (2,1) resistive tearing mode by ECCD is demonstrated and the relevant stabilization mechanism is determined. Consequences of the shifting of the mode rational surface in response to the injected current are explored, and the characteristic short-time responses of resistive tearing modes to spatial ECCD alignments which are stabilizing are also noted. We discuss the relevance of this work to the development of more comprehensive predictive models for ECCD-based mitigation and control of neoclassical tearing modes.

Mixing of an Airblast-atomized Fuel Spray Injected into a Crossflow of Air

NASA Technical Reports Server (NTRS)

Leong, May Y.; McDonell, Vincent G.; Samuelsen, G. Scott

2000-01-01

The injection of a spray of fuel droplets into a crossflow of air provides a means of rapidly mixing liquid fuel and air for combustion applications. Injecting the liquid as a spray reduces the mixing length needed to accommodate liquid breakup, while the transverse injection of the spray into the air stream takes advantage of the dynamic mixing induced by the jet-crossflow interaction. The structure of the spray, formed from a model plain-jet airblast atomizer, is investigated in order to determine and understand the factors leading to its dispersion. To attain this goal, the problem is divided into the following tasks which involve: (1) developing planar imaging techniques that visualize fuel and air distributions in the spray, (2) characterizing the airblast spray without a crossflow, and (3) characterizing the airblast spray upon injection into a crossflow. Geometric and operating conditions are varied in order to affect the atomization, penetration, and dispersion of the spray into the crossflow. The airblast spray is first characterized, using imaging techniques, as it issues into a quiescent environment. The spray breakup modes are classified in a liquid Reynolds number versus airblast Weber number regime chart. This work focuses on sprays formed by the "prompt" atomization mode, which induces a well-atomized and well-dispersed spray, and which also produces a two-lobed liquid distribution corresponding to the atomizing air passageways in the injector. The characterization of the spray jet injected into the crossflow reveals the different processes that control its dispersion. Correlations that describe the inner and outer boundaries of the spray jet are developed, using the definition of a two-phase momentum-flux ratio. Cross-sections of the liquid spray depict elliptically-shaped distributions, with the exception of the finely-atomized sprays which show kidney-shaped distributions reminiscent of those obtained in gaseous jet in crossflow systems. A droplet trajectory analysis overpredicts the liquid mass penetration, and indicates a need for a more rigorous model to account for the three-dimensional mixing field induced by the jet-crossflow interaction. Nonetheless, the general procedures and criteria that are outlined can be used to efficiently assess and compare the quality of sprays formed under different conditions.

Enhancement of the performance of GaN IMPATT diodes by negative differential mobility

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

Dai, Yang; Yang, Lin’an, E-mail: layang@xidian.edu.cn; Chen, Qing

2016-05-15

A theoretical analysis of high-efficiency punch-through operation GaN-based terahertz IMPATT diodes has been carried out in this paper. It is shown that the negative differential mobility (NDM) characteristics of GaN coupled with the space charge effect acting as a self-feedback system can markedly increase the drift velocity of injection carriers, and thereby enhance diode performance under appropriate external RF voltage. The behavior of traveling electrons in the transit zone is investigated in detail. It is found that the IMPATT diode with a punch-through structure operating in the NDM mode exhibits superior characteristics compared with the equivalent diode operating in themore » Si-like constant mobility mode. In particular, the NDM-mode diode can tolerate a larger RF voltage swing than that operating in constant mobility mode. Numerical simulation results reveal that the highest efficiency of 26.6% and maximum RF power of 2.29 W can be achieved for the NDM-mode diode at a frequency of 225 GHz. A highest efficiency of 19.0% and maximum RF power of 1.58 W are obtained for the diode with constant mobility.« less

Kinetic-MHD hybrid simulation of fishbone modes excited by fast ions on the experimental advanced superconducting tokamak (EAST)

NASA Astrophysics Data System (ADS)

Pei, Youbin; Xiang, Nong; Hu, Youjun; Todo, Y.; Li, Guoqiang; Shen, Wei; Xu, Liqing

2017-03-01

Kinetic-MagnetoHydroDynamic hybrid simulations are carried out to investigate fishbone modes excited by fast ions on the Experimental Advanced Superconducting Tokamak. The simulations use realistic equilibrium reconstructed from experiment data with the constraint of the q = 1 surface location (q is the safety factor). Anisotropic slowing down distribution is used to model the distribution of the fast ions from neutral beam injection. The resonance condition is used to identify the interaction between the fishbone mode and the fast ions, which shows that the fishbone mode is simultaneously in resonance with the bounce motion of the trapped particles and the transit motion of the passing particles. Both the passing and trapped particles are important in destabilizing the fishbone mode. The simulations show that the mode frequency chirps down as the mode reaches the nonlinear stage, during which there is a substantial flattening of the perpendicular pressure of fast ions, compared with that of the parallel pressure. For passing particles, the resonance remains within the q = 1 surface, while, for trapped particles, the resonant location moves out radially during the nonlinear evolution. In addition, parameter scanning is performed to examine the dependence of the linear frequency and growth rate of fishbones on the pressure and injection velocity of fast ions.

Time-domain measurement of terahertz frequency magnetoplasmon resonances in a two-dimensional electron system by the direct injection of picosecond pulsed currents

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

Wu, Jingbo; Mayorov, Alexander S.; Wood, Christopher D.

2016-02-29

We have investigated terahertz (THz) frequency magnetoplasmon resonances in a two-dimensional electron system through the direct injection of picosecond duration current pulses. The evolution of the time-domain signals was measured as a function of magnetic field, and the results were found to be in agreement with calculations using a mode-matching approach for four modes observed in the frequency range above 0.1 THz. This introduces a generic technique suitable for sampling ultrafast carrier dynamics in low-dimensional semiconductor nanostructures at THz frequencies.

Automated on-line renewable solid-phase extraction-liquid chromatography exploiting multisyringe flow injection-bead injection lab-on-valve analysis.

PubMed

Quintana, José Benito; Miró, Manuel; Estela, José Manuel; Cerdà, Víctor

2006-04-15

In this paper, the third generation of flow injection analysis, also named the lab-on-valve (LOV) approach, is proposed for the first time as a front end to high-performance liquid chromatography (HPLC) for on-line solid-phase extraction (SPE) sample processing by exploiting the bead injection (BI) concept. The proposed microanalytical system based on discontinuous programmable flow features automated packing (and withdrawal after single use) of a small amount of sorbent (<5 mg) into the microconduits of the flow network and quantitative elution of sorbed species into a narrow band (150 microL of 95% MeOH). The hyphenation of multisyringe flow injection analysis (MSFIA) with BI-LOV prior to HPLC analysis is utilized for on-line postextraction treatment to ensure chemical compatibility between the eluate medium and the initial HPLC gradient conditions. This circumvents the band-broadening effect commonly observed in conventional on-line SPE-based sample processors due to the low eluting strength of the mobile phase. The potential of the novel MSFI-BI-LOV hyphenation for on-line handling of complex environmental and biological samples prior to reversed-phase chromatographic separations was assessed for the expeditious determination of five acidic pharmaceutical residues (viz., ketoprofen, naproxen, bezafibrate, diclofenac, and ibuprofen) and one metabolite (viz., salicylic acid) in surface water, urban wastewater, and urine. To this end, the copolymeric divinylbenzene-co-n-vinylpyrrolidone beads (Oasis HLB) were utilized as renewable sorptive entities in the micromachined unit. The automated analytical method features relative recovery percentages of >88%, limits of detection within the range 0.02-0.67 ng mL(-1), and coefficients of variation <11% for the column renewable mode and gives rise to a drastic reduction in operation costs ( approximately 25-fold) as compared to on-line column switching systems.

Steady state scenario development with elevated minimum safety factor on DIII-D

DOE PAGES

Holcomb, Christopher T.; Ferron, John R.; Luce, Timothy C.; ...

2014-08-15

On DIII-D, a high β scenario with minimum safety factor (q min) near 1.4 has been optimized with new tools and shown to be a favourable candidate for long pulse or steady state operation in future devices. Furthermore, the new capability to redirect up to 5 MW of neutral beam injection (NBI) from on- to off-axis improves the ability to sustain elevated q min with a less peaked pressure profile. The observed changes increase the ideal magnetohydrodynamics (MHD) n = 1 mode β N limit thus providing a path forward for increasing the noninductive current drive fraction by operating atmore » high β N. Quasi-stationary discharges free of tearing modes have been sustained at βN = 3.5 and β T = 3.6% for two current profile diffusion timescales (about 3 s) limited by neutral beam duration. The discharge performance has normalized fusion performance expected to give fusion gain Q ≈ 5 in a device the size of ITER. Analysis of the poloidal flux evolution and current drive balance show that the loop voltage profile is almost relaxed even with 25% of the current driven inductively, and q min remains elevated near 1.4. Our observations increase confidence that the current profile will not evolve to one unstable to a tearing mode. In preliminary tests a divertor heat flux reduction technique based on producing a radiating mantle with neon injection appears compatible with this operating scenario. 0D model extrapolations suggest it may be possible to push this scenario up to 100% noninductive current drive by raising β N. Similar discharges with q min = 1.5–2 were susceptible to tearing modes and off-axis fishbones, and with q min > 2 lower normalized global energy confinement time is observed.« less

Comparison of a high temperature torch integrated sample introduction system with a desolvation system for the analysis of microsamples through inductively coupled plasma mass spectrometry

NASA Astrophysics Data System (ADS)

Sánchez, Raquel; Cañabate, Águeda; Bresson, Carole; Chartier, Frédéric; Isnard, Hélène; Maestre, Salvador; Nonell, Anthony; Todolí, José-Luis

2017-03-01

This work describes for the first time the comparison of the analytical performances obtained with a high temperature torch integrated sample introduction system (hTISIS) against those found with a commercially available desolvation system (APEX) associated with inductively coupled plasma mass spectrometry (ICP-MS). A double pass spray chamber was taken as the reference system. Similar detection limits and sensitivities were obtained in continuous injection mode at low liquid flow rates for the APEX and hTISIS operating at high temperatures. In contrast, in the air-segmented injection mode, the detection limits obtained with hTISIS at high temperatures were up to 12 times lower than those found for the APEX. Regarding memory effects, wash out times were shorter in continuous mode and peaks were narrower in air segmented mode for the hTISIS as compared to the APEX. Non spectral interferences (matrix effects) were studied with 10% nitric acid, 2% methanol, for an ICP multielemental solution and a hydro-organic matrix containing 70% (v/v) acetonitrile in water, 15 mmol L- 1 ammonium acetate and 0.5% formic acid containing lanthanide complexes. In all the cases, matrix effects were less severe for the hTISIS operating at 200 °C and the APEX than for the double pass spray chamber. Finally, two spiked reference materials (sea water and Antartic krill) were analyzed. The hTISIS operating at 200 °C gave the best results compared to those obtained with the APEX and the double pass spray chamber. In conclusion, despite the simplicity of the hTISIS, it provided, at low liquid flow rates, results similar to or better than those obtained with the by other sample introduction systems.

Orbital Injection of the SEDSAT Satellite: Tethered Systems Dynamics and Flight Data Analysis

NASA Technical Reports Server (NTRS)

Lorenzini, Enrico C.; Gullahorn, Gordon E.; Cosmo, Mario L.; Ruiz, Manuel; Pelaez, Jesus

1996-01-01

This report deals with the following topics which are all related to the orbital injection of the SEDSAT satellite: Dynamics and Stability of Tether Oscillations after the First Cut. The dynamics of the tether after the first cut (i.e., without the Shuttle attached to it) is investigated. The tether oscillations with the free end are analyzed in order to assess the stability of the rectilinear configuration in between the two tether cuts; analysis of Unstable Modes. The unstable modes that appear for high libration angles are further investigated in order to determine their occurrences and the possible transition from bound librations to rotations; Orbital Release Strategies for SEDSAT. A parametric analysis of the orbital decay rate of the SEDSAT satellite after the two tether cuts has been carried out as a function of the following free parameters: libration amplitude at the end of deployment, deviation angle from LV at the first cut, and orbital anomaly at the second cut. The values of these parameters that provide a minimum orbital decay rate of the satellite (after the two cuts) have been computed; and Dynamics and Control of SEDSAT. The deployment control law has been modified to cope with the new ejection velocity of the satellite from the Shuttle cargo bay. New reference profiles have been derived as well as new control parameters. Timing errors at the satellite release as a function of the variations of the initial conditions and the tension model parameters have been estimated for the modified control law.

Mode selection and frequency tuning by injection in pulsed TEA-CO2 lasers

NASA Technical Reports Server (NTRS)

Flamant, P. H.; Menzies, R. T.

1983-01-01

An analytical model characterizing pulsed-TEA-CO2-laser injection locking by tunable CW-laser radiation is presented and used to explore the requirements for SLM pulse generation. Photon-density-rate equations describing the laser mechanism are analyzed in terms of the mode competition between photon densities emitted at two frequencies. The expression derived for pulsed dye lasers is extended to homogeneously broadened CO2 lasers, and locking time is defined as a function of laser parameters. The extent to which injected radiation can be detuned from the CO2 line center and continue to produce SLM pulses is investigated experimentally in terms of the analytical framework. The dependence of locking time on the detuning/pressure-broadened-halfwidth ratio is seen as important for spectroscopic applications requiring tuning within the TEA-laser line-gain bandwidth.

Enhanced H-mode pedestals with lithium injection in DIII-D

DOE PAGES

Osborne, Thomas H.; Jackson, Gary L.; Yan, Zheng; ...

2015-05-08

Periods of edge localized mode (ELM)-free H-mode with increased pedestal pressure and width were observed in the DIII-D tokamak when density fluctuations localized to the region near the separatrix were present. Injection of a powder of 45 μm diameter lithium particles increased the duration of the enhanced pedestal phases to up to 350 ms, and also increased the likelihood of a transition to the enhanced phase. Lithium injection at a level sufficient for triggering the extended enhanced phases resulted in significant lithium in the plasma core, but carbon and other higher Z impurities as well as radiated power levels weremore » reduced. Recycling of the working deuterium gas appeared unaffected by this level of lithium injection. The ion scale, k θ ρ s ~ 0.1–0.2, density fluctuations propagated in the electron drift direction with f ~ 80 kHz and occurred in bursts every ~1 ms. The fluctuation bursts correlated with plasma loss resulting in a flattening of the pressure profile in a region near the separatrix. This localized flattening 2 allowed higher overall pedestal pressure at the peeling-ballooning stability limit and higher pressure than expected under the EPED model due to reduction of the pressure gradient below the “ballooning critical profile”. Furthermore, reduction of the ion pressure by lithium dilution may contribute to the long ELM-free periods.« less

Plasma response to sustainment with imposed-dynamo current drive in HIT-SI and HIT-SI3

NASA Astrophysics Data System (ADS)

Hossack, A. C.; Jarboe, T. R.; Chandra, R. N.; Morgan, K. D.; Sutherland, D. A.; Penna, J. M.; Everson, C. J.; Nelson, B. A.

2017-07-01

The helicity injected torus—steady inductive (HIT-SI) program studies efficient, steady-state current drive for magnetic confinement plasmas using a novel experimental method. Stable, high-beta spheromaks have been sustained using steady, inductive current drive. Externally induced loop voltage and magnetic flux are oscillated together so that helicity and power injection are always positive, sustaining the edge plasma current indefinitely. Imposed-dynamo current drive (IDCD) theory further shows that the entire plasma current is sustained. The method is ideal for low aspect ratio, toroidal geometries with closed flux surfaces. Experimental studies of spheromak plasmas sustained with IDCD have shown stable magnetic profiles with evidence of pressure confinement. New measurements show coherent motion of a stable spheromak in response to the imposed perturbations. On the original device two helicity injectors were mounted on either side of the spheromak and the injected mode spectrum was predominantly n  =  1. Coherent, rigid motion indicates that the spheromak is stable and a lack of plasma-generated n  =  1 energy indicates that the maximum q is maintained below 1 during sustainment. Results from the HIT-SI3 device are also presented. Three inductive helicity injectors are mounted on one side of the spheromak flux conserver. Varying the relative injector phasing changes the injected mode spectrum which includes n  =  2, 3, and higher modes.

Three-dimensional simulation of H-mode plasmas with localized divertor impurity injection on Alcator C-Mod using the edge transport code EMC3-EIRENE

DOE PAGES

Lore, Jeremy D.; Reinke, M. L.; Brunner, D.; ...

2015-04-28

We study experiments in Alcator C-Mod to assess the level of toroidal asymmetry in divertor conditions resulting from poloidally and toroidally localized extrinsic impurity gas seeding show a weak toroidal peaking (~1.1) in divertor electron temperatures for high-power enhanced D-alpha H-modeplasmas. This is in contrast to similar experiments in Ohmically heated L-modeplasmas, which showed a clear toroidal modulation in the divertor electron temperature. Modeling of these experiments using the 3D edge transport code EMC3-EIRENE [Y. Feng et al., J. Nucl. Mater. 241, 930 (1997)] qualitatively reproduces these trends, and indicates that the different response in the simulations is due tomore » the ionization location of the injected nitrogen. Low electron temperatures in the private flux region (PFR) in L-mode result in a PFR plasma that is nearly transparent to neutral nitrogen, while in H-mode the impurities are ionized in close proximity to the injection location, with this latter case yielding a largely axisymmetric radiation pattern in the scrape-off-layer. In conclusion, the consequences for the ITER gas injection system are discussed. Quantitative agreement with the experiment is lacking in some areas, suggesting potential areas for improving the physics model in EMC3-EIRENE.« less

Numerical Simulation of a Double-anode Magnetron Injection Gun for 110 GHz, 1 MW Gyrotron

NASA Astrophysics Data System (ADS)

Singh, Udaybir; Kumar, Nitin; Purohit, L. P.; Sinha, Ashok K.

2010-07-01

A 40 A double-anode magnetron injection gun for a 1 MW, 110 GHz gyrotron has been designed. The preliminary design has been obtained by using some trade-off equations. The electron beam analysis has been performed by using the commercially available code EGUN and the in-house developed code MIGANS. The operating mode of the gyrotron is TE22,6 and it is operated in the fundamental harmonic. The electron beam with a low transverse velocity spread ( δ {β_{ bot max }} = 2.26% ) and the transverse-to-axial velocity ratio of the electron beam (α) = 1.37 is obtained. The simulated results of the MIG obtained with the EGUN code have been validated with another trajectory code TRAK. The results on the design output parameters obtained by both the codes are in good agreement. The sensitivity analysis has been carried out by changing the different gun parameters to decide the fabrication tolerance.

Simultaneous determination of fluoroquinolones in environmental water by liquid chromatography-tandem mass spectrometry with direct injection: A green approach.

PubMed

Denadai, Marina; Cass, Quezia Bezerra

2015-10-30

This work describes an on-line multi-residue method for simultaneous quantification of ciprofloxacin, enrofloxacin, gemifloxacin, moxifloxacin, norfloxacin and ofloxacin in superficial and wastewater samples. For that, an octyl restricted-access media bovine serum albumin column (RAM-BSA C8) was used for sample clean-up, enrichment and analysis with quantitation carried out by tandem mass spectrometry. For water samples volumes of only 500μL the method provided good selectivity, extraction efficiency, accuracy, and precision with quantification limits in the order of 20-150ngL(-1). Out of the six fluoroquinolones only ciprofloxacin (195ngL(-1)) and norfloxacin (270ngL(-1)) were quantified in an influent sample of the wastewater treatment plant (WWTP) of São Carlos (SP, Brazil). None were found in the superficial water samples analyzed. The capability of injecting native sample in an automated mode provides high productivity and represents a greener approach in environmental sample analysis. Copyright © 2015 Elsevier B.V. All rights reserved.

High-power actively Q-switched single-mode 1342 nm Nd:YVO₄ ring laser, injection-locked by a cw single-frequency microchip laser.

PubMed

Koch, Peter; Bartschke, Juergen; L'huillier, Johannes A

2015-11-30

In this paper we report on the realization of a single-mode Q-switched Nd:YVO₄ ring laser at 1342 nm. Unidirectional and single-mode operation of the ring laser is achieved by injection-locking with a continuous wave Nd:YVO₄ microchip laser, emitting a single-frequency power of up to 40 mW. The ring laser provides a single-mode power of 13.9 W at 10 kHz pulse repetition frequency with a pulse duration of 18.2 ns and an excellent beam quality (M² < 1.05). By frequency doubling of the fundamental 1342 nm laser, a power of 8.7 W at 671 nm with a pulse duration of 14.8 ns and a beam propagation factor of M² < 1.1 is obtained. The 671 nm radiation features a long-term spectral width of 75 MHz.

Frequency stabilization in injection controlled pulsed CO2 lasers

NASA Technical Reports Server (NTRS)

Menzies, Robert T.; Ancellet, Gerard M.

1987-01-01

Longitudinal mode selection by injection has been demonstrated as a viable technique for tailoring a TEA-CO2 laser with pulse energies of a Joule or greater to fit the requirements of a coherent lidar transmitter. Once reliable generation of single-longitudinal-mode (SLM) pulses is obtained, one can study the intrapulse frequency variation and attempt to determine the sources of frequency sweeping, or chirp. These sources include the effect of the decaying plasma, the thermal gradient due to the energy dissipation associated with the laser mechanism itself, and the pressure shift of the center frequency of the laser transition. The use of the positive-branch unstable resonator as an efficient means of coupling a discharge with transverse spatial dimensions of the order of centimeters to an optical cavity mode introduces another concern: namely, what can be done to emphasize transverse mode discrimination in an unstable resonator cavity while maintaining high coupling efficiency. These issues are briefly discussed in the paper, and representative experimental examples are included.

LEDs based upon AlGaInP heterostructures with multiple quantum wells: comparison of fast neutrons and gamma-quanta irradiation

NASA Astrophysics Data System (ADS)

Gradoboev, A. V.; Orlova, K. N.; Simonova, A. V.

2018-05-01

The paper presents the research results of watt and volt characteristics of LEDs based upon AlGaInP heterostructures with multiple quantum wells in the active region. The research is completed for LEDs (emission wavelengths 624 nm and 590 nm) under irradiation by fast neutron and gamma-quanta in passive powering mode. Watt-voltage characteristics in the average and high electron injection areas are described as a power function of the operating voltage. It has been revealed that the LEDs transition from average electron injection area to high electron injection area occurs by overcoming the transition area. It disappears as it get closer to the limit result of the irradiation LEDs that is low electron injection mode in the entire supply voltage range. It has been established that the gamma radiation facilitates initial defects restructuring only 42% compared to 100% when irradiation is performed by fast neutrons. Ratio between measured on the boundary between low and average electron injection areas current value and the contribution magnitude of the first stage LEDs emissive power reducing is established. It is allows to predict LEDs resistance to irradiation by fast neutrons and gamma rays.

ELM elimination with lithium aerosol injection in upper-single null discharges using the tungsten divertor in EAST

NASA Astrophysics Data System (ADS)

Sun, Z.; Maingi, R.; Hu, J.; Lunsford, R.; Diallo, A.; Tritz, K.; Osborne, T.; Canik, J.; Zuo, G.; Wang, L.; Xu, G.; Gong, X.; EAST Team Team

2017-10-01

A reproducible, fully non-inductive H-mode regime devoid of large ELMs has been achieved by continuous Li injection in EAST into the upper `ITER-like' tungsten divertor, extending previous results on the graphite divertor. These discharges did not suffer from density or impurity accumulation, and maintained constant core radiated power. The new results extend the energy confinement multiplier H98(y,2) 1.2, as compared to H98(y,2) 0.75 previously on the graphite divertor. The observed ELM elimination is correlated with a decrease in particle recycling, as expected from the strong Li coating before the experiment, and real-time Li aerosol injection. In addition, core W concentration was reduced during the Li injection. ELM elimination is likely related to the reduced recycling and density /temperature profile changes. A low-n electromagnetic coherent mode (MCM) at 40kHz became stronger in amplitude and also more coherent. The MCM shows strong magnetic fluctuations as measured by fast Mirnov coils, but weak density fluctuations. As compared to the graphite divertor, Li injection into the tungsten divertor eliminated ELMs at twice the previous auxiliary heating power, and reduced pedestal collisionality.

Observation of internal transport barrier in ELMy H-mode plasmas on the EAST tokamak

NASA Astrophysics Data System (ADS)

Yang, Y.; Gao, X.; Liu, H. Q.; Li, G. Q.; Zhang, T.; Zeng, L.; Liu, Y. K.; Wu, M. Q.; Kong, D. F.; Ming, T. F.; Han, X.; Wang, Y. M.; Zang, Q.; Lyu, B.; Li, Y. Y.; Duan, Y. M.; Zhong, F. B.; Li, K.; Xu, L. Q.; Gong, X. Z.; Sun, Y. W.; Qian, J. P.; Ding, B. J.; Liu, Z. X.; Liu, F. K.; Hu, C. D.; Xiang, N.; Liang, Y. F.; Zhang, X. D.; Wan, B. N.; Li, J. G.; Wan, Y. X.; EAST Team

2017-08-01

The internal transport barrier (ITB) has been obtained in ELMy H-mode plasmas by neutron beam injection and lower hybrid wave heating on the Experimental Advanced Superconducting Tokamak (EAST). The ITB structure has been observed in profiles of ion temperature, electron temperature, and electron density within ρ < 0.5. It was also observed that the ITB formation is stepwise. Due to the ITB formation, the confinement quality H 98y2 increases from 1 to 1.1 and the normalized beta, β N, increases from 1.5 to near 2. The fishbone activity observed during the ITB phase suggests the central safety factor q(0) ˜ 1. Transport coefficients are calculated by particle balance and power balance analysis, showing an obvious reduction after the ITB formation.

Few-mode fiber based Raman distributed temperature sensing.

PubMed

Wang, Meng; Wu, Hao; Tang, Ming; Zhao, Zhiyong; Dang, Yunli; Zhao, Can; Liao, Ruolin; Chen, Wen; Fu, Songnian; Yang, Chen; Tong, Weijun; Shum, Perry Ping; Liu, Deming

2017-03-06

We proposed and experimentally demonstrated a few mode fiber (FMF) based Raman distributed temperature sensor (RDTS) to extend the sensing distance with enhanced signal-to-noise ratio (SNR) of backscattered anti-Stokes spontaneous Raman scattering. Operating in the quasi-single mode (QSM) with efficient fundamental mode excitement, the FMF allows much larger input pump power before the onset of stimulated Raman scattering compared with the standard single mode fiber (SSMF) and mitigates the detrimental differential mode group delay (DMGD) existing in the conventional multimode fiber (MMF) based RDTS system. Comprehensive theoretical analysis has been conducted to reveal the benefits of RDTS brought by QSM operated FMFs with the consideration of geometric/optical parameters of different FMFs. The measurement uncertainty of FMF based scheme has also been evaluated. Among fibers being investigated and compared (SSMF, 2-mode and 4-mode FMFs, respectively), although an ideal 4-mode FMF based RDTS has the largest SNR enhancement in principle, real fabrication imperfections and larger splicing loss degrade its performance. While the 2-mode FMF based system outperforms in longer distance measurement, which agrees well with the theoretical calculations considering real experimental parameters. Using the conventional RDTS hardware, a 30-ns single pulse at 1550nm has been injected as the pump; the obtained temperature resolutions at 20km distance are estimated to be about 10°C, 7°C and 6°C for the SSMF, 4-mode and 2-mode FMFs, respectively. About 4°C improvement over SSMF on temperature resolution at the fiber end with 3m spatial resolution within 80s measuring time over 20km 2-mode FMFs have been achieved.

Demonstration of L-band DP-QPSK transmission over FSO and fiber channels employing InAs/InP quantum-dash laser source

NASA Astrophysics Data System (ADS)

Shemis, M. A.; Khan, M. T. A.; Alkhazraji, E.; Ragheb, A. M.; Esmail, M. A.; Fathallah, H.; Qureshi, K. K.; Alshebeili, S.; Khan, M. Z. M.

2018-03-01

The next generation of optical access communication networks that support 100 Gbps and beyond, require advances in modulation schemes, spectrum utilization, new transmission bands, and efficient devices, particularly laser diodes. In this paper, we investigated the viability of new-class of InAs/InP Quantum-dash laser diode (Qdash-LD) exhibiting multiple longitudinal light modes in the L-band to carry high-speed data rate for access network applications. We exploited external and self injection-locking techniques on Qdash-LD to generate large number of stable and tunable locked modes, and compared them. To stem the capability of each locked mode as a potential subcarrier, data transmission is carried out over two mediums; single mode fiber (SMF) and free space optics (FSO) to emulate real deployment scenarios of optical networks. The results showed that with external-injection locking (EIL), an error-free transmission of 100 Gbps dual polarization quadrature phase shift keying (DP-QPSK) signal is demonstrated over 10 km SMF and 4 m indoor FSO channels, with capability of reaching up to 128 Gbps, demonstrated under back-to-back (BTB) configuration. On the other hand, using self-injection locking (SIL) scheme, a successful data transmission of 64 Gbps and 128 Gbps DP-QPSK signal over 20 km SMF and 10 m indoor FSO links, respectively, is achieved.

Multiple harmonic frequencies resonant cavity design and half-scale prototype measurements for a fast kicker

DOE PAGES

Huang, Yulu; Wang, Haipeng; Wang, Shaoheng; ...

2016-12-09

Quarter wavelength resonator (QWR) based deflecting cavities with the capability of supporting multiple odd-harmonic modes have been developed for an ultrafast periodic kicker system in the proposed Jefferson Lab Electron Ion Collider (JLEIC, formerly MEIC). Previous work on the kicking pulse synthesis and the transverse beam dynamics tracking simulations show that a flat-top kicking pulse can be generated with minimal emittance growth during injection and circulation of the cooling electron bunches. This flat-top kicking pulse can be obtained when a DC component and 10 harmonic modes with appropriate amplitude and phase are combined together. To support 10 such harmonic modes,more » four QWR cavities are used with 5, 3, 1, and 1 modes, respectively. In the multiple-mode cavities, several slightly tapered segments of the inner conductor are introduced to tune the higher order deflecting modes to be harmonic, and stub tuners are used to fine tune each frequency to compensate for potential errors. In this paper, we summarize the electromagnetic design of the five-mode cavity, including the geometry optimization to get high transverse shunt impedance, the frequency tuning and sensitivity analysis, and the single loop coupler design for coupling to all of the harmonic modes. In particular we report on the design and fabrication of a half-scale copper prototype of this proof-of-principle five-odd-mode cavity, as well as the rf bench measurements. Lastly, we demonstrate mode superposition in this cavity experimentally, which illustrates the kicking pulse generation concept.« less

Coulometric sodium chloride removal system with Nafion membrane for seawater sample treatment.

PubMed

Grygolowicz-Pawlak, Ewa; Sohail, Manzar; Pawlak, Marcin; Neel, Bastien; Shvarev, Alexey; de Marco, Roland; Bakker, Eric

2012-07-17

Seawater analysis is one of the most challenging in the field of environmental monitoring, mainly due to disparate concentration levels between the analyte and the salt matrix causing interferences in a variety of analytical techniques. We propose here a miniature electrochemical sample pretreatment system for a rapid removal of NaCl utilizing the coaxial arrangement of an electrode and a tubular Nafion membrane. Upon electrolysis, chloride is deposited at the Ag electrode as AgCl and the sodium counterions are transported across the membrane. This cell was found to work efficiently at potentials higher than 400 mV in both stationary and flow injection mode. Substantial residual currents observed during electrolysis were found to be a result of NaCl back diffusion from the outer side of the membrane due to insufficient permselectivity of the Nafion membrane. It was demonstrated that the residual current can be significantly reduced by adjusting the concentration of the outer solution. On the basis of ion chromatography results, it was found that the designed cell used in flow injection electrolysis mode reduced the NaCl concentration from 0.6 M to 3 mM. This attempt is very important in view of nutrient analysis in seawater where NaCl is a major interfering agent. We demonstrate that the pretreatment of artificial seawater samples does not reduce the content of nitrite or nitrate ions upon electrolysis. A simple diffusion/extraction steady state model is proposed for the optimization of the electrolysis cell characteristics.

Performance of an Axisymmetric Rocket Based Combined Cycle Engine During Rocket Only Operation Using Linear Regression Analysis

NASA Technical Reports Server (NTRS)

Smith, Timothy D.; Steffen, Christopher J., Jr.; Yungster, Shaye; Keller, Dennis J.

1998-01-01

The all rocket mode of operation is shown to be a critical factor in the overall performance of a rocket based combined cycle (RBCC) vehicle. An axisymmetric RBCC engine was used to determine specific impulse efficiency values based upon both full flow and gas generator configurations. Design of experiments methodology was used to construct a test matrix and multiple linear regression analysis was used to build parametric models. The main parameters investigated in this study were: rocket chamber pressure, rocket exit area ratio, injected secondary flow, mixer-ejector inlet area, mixer-ejector area ratio, and mixer-ejector length-to-inlet diameter ratio. A perfect gas computational fluid dynamics analysis, using both the Spalart-Allmaras and k-omega turbulence models, was performed with the NPARC code to obtain values of vacuum specific impulse. Results from the multiple linear regression analysis showed that for both the full flow and gas generator configurations increasing mixer-ejector area ratio and rocket area ratio increase performance, while increasing mixer-ejector inlet area ratio and mixer-ejector length-to-diameter ratio decrease performance. Increasing injected secondary flow increased performance for the gas generator analysis, but was not statistically significant for the full flow analysis. Chamber pressure was found to be not statistically significant.

Uncertainty Quantification for Robust Control of Wind Turbines using Sliding Mode Observer

NASA Astrophysics Data System (ADS)

Schulte, Horst

2016-09-01

A new quantification method of uncertain models for robust wind turbine control using sliding-mode techniques is presented with the objective to improve active load mitigation. This approach is based on the so-called equivalent output injection signal, which corresponds to the average behavior of the discontinuous switching term, establishing and maintaining a motion on a so-called sliding surface. The injection signal is directly evaluated to obtain estimates of the uncertainty bounds of external disturbances and parameter uncertainties. The applicability of the proposed method is illustrated by the quantification of a four degree-of-freedom model of the NREL 5MW reference turbine containing uncertainties.

Mixed mode control method and engine using same

DOEpatents

Kesse, Mary L [Peoria, IL; Duffy, Kevin P [Metamora, IL

2007-04-10

A method of mixed mode operation of an internal combustion engine includes the steps of controlling a homogeneous charge combustion event timing in a given engine cycle, and controlling a conventional charge injection event to be at least a predetermined time after the homogeneous charge combustion event. An internal combustion engine is provided, including an electronic controller having a computer readable medium with a combustion timing control algorithm recorded thereon, the control algorithm including means for controlling a homogeneous charge combustion event timing and means for controlling a conventional injection event timing to be at least a predetermined time from the homogeneous charge combustion event.

Suppression and spectral splitting of the amplitude noise due to mode beatings in a single-frequency injection laser

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

Bogatov, A.P.; Eliseev, P.G.; Kobildzhanov, O.A.

1987-06-01

Investigations of intensity fluctuations in a single-frequency injection laser showed that they are due to beatings between coherent field and superluminescent spontaneous emission. It has been experimentally found that in the region of developed laser emission, the level of fluctuations is decreased with an increase of the output power, and so the relative spectral shift of external cavity superluminescent mode frequencies is dependent on the laser output power. The explanation of this phenomenon was made on the basis of the mechanism of a nonlinear interaction of a field in the active region of a laser diode.

A narrow-band injection-seeded pulsed titanium:sapphire oscillator-amplifier system with on-line chirp analysis for high-resolution spectroscopy.

PubMed

Hannemann, S; van Duijn, E-J; Ubachs, W

2007-10-01

A narrow-band tunable injection-seeded pulsed titanium:sapphire laser system has been developed for application in high-resolution spectroscopic studies at the fundamental wavelengths in the near infrared as well as in the ultraviolet, deep ultraviolet, and extreme ultraviolet after upconversion. Special focus is on the quantitative assessment of the frequency characteristics of the oscillator-amplifier system on a pulse-to-pulse basis. Frequency offsets between continuous-wave seed light and the pulsed output are measured as well as linear chirps attributed mainly to mode pulling effects in the oscillator cavity. Operational conditions of the laser are found in which these offset and chirp effects are minimal. Absolute frequency calibration at the megahertz level of accuracy is demonstrated on various atomic and molecular resonance lines.

Microstructural study of natural fractures in Cape Roberts Project 3 core, Western Ross Sea, Antarctica

USGS Publications Warehouse

Millan, C.; Wilson, T.; Paulsen, T.

2007-01-01

Microstructures in natural fractures in core recovered offshore from Cape Roberts, Ross Sea, Antarctica, provide new constraints on the relative timing of faulting and sedimentation in the Victoria Land Basin along the Transantarctic Mountain rift flank. This study characterizes the textures, fabrics and grain-scale structures from thin section analysis of samples of microfaults, veins, and clastic dikes. Microfaults are abundant and display two different types of textures, interpreted to record two different deformation modes: pre-lithification shearing and brittle faulting of cohesive sediment. Both clastic dikes and calcite veins commonly follow fault planes, indicating that injections of liquefied sediment and circulating fluids used pre-existing faults as conduits. The close association of clastic injections, diagenetic mineralization, and faulting indicates that faulting was synchronous with deposition in the rift basin

Inactivation of Bacteria in Oil Field Injected Water by a Pulsed Plasma Discharge Process

NASA Astrophysics Data System (ADS)

Xin, Qing; Li, Zhongjian; Lei, Lecheng; Yang, Bin

2016-09-01

Pulsed plasma discharge was employed to inactivate bacteria in the injection water for an oil field. The effects of water conductivity and initial concentration of bacteria on elimination efficiency were investigated in the batch and continuous flow modes. It was demonstrated that Fe2+ contained in injection water could enhance the elimination efficiency greatly. The addition of reducing agent glutathione (GSH) indicated that active radicals generated by pulsed plasma discharges played an important role in the inactivation of bacteria. Moreover, it was found that the microbial inactivation process for both batch and continuous flow mode well fitted the model based on the Weibull's survival function. supported by Zhejiang Province Welfare Technology Applied Research Project of China (No. 2014C31137), National Natural Science Foundation of China (Nos. 21436007 and U1462201), and the Fundamental Research Funds for the Central Universities of China (No. 2015QNA4032)

Revisitation of the dipole tracer test for heterogeneous porous formations

NASA Astrophysics Data System (ADS)

Zech, Alraune; D'Angelo, Claudia; Attinger, Sabine; Fiori, Aldo

2018-05-01

In this paper, a new analytical solution for interpreting dipole tests in heterogeneous media is derived by associating the shape of the tracer breakthrough curve with the log-conductivity variance. It is presented how the solution can be used for interpretation of dipole field test in view of geostatistical aquifer characterization on three illustrative examples. The analytical solution for the tracer breakthrough curve at the pumping well in a dipole tracer test is developed by considering a perfectly stratified formation. The analysis is carried out making use of the travel time of a generic solute particle, from the injection to the pumping well. Injection conditions are adapted to different possible field setting. Solutions are presented for resident and flux proportional injection mode as well as for an instantaneous pulse of solute and continuous solute injections. The analytical form of the solution allows a detailed investigation on the impact of heterogeneity, the tracer input conditions and ergodicity conditions at the well. The impact of heterogeneity manifests in a significant spreading of solute particles that increases the natural tendency to spreading induced by the dipole setup. Furthermore, with increasing heterogeneity the number of layers needed to reach ergodic conditions become larger. Thus, dipole test in highly heterogeneous aquifers might take place under non-ergodic conditions giving that the log-conductivity variance is underestimated. The method is a promising geostatistical analyzing tool being the first analytical solution for dipole tracer test analysis taking heterogeneity of hydraulic conductivity into account.

[Simultaneous determination of 4 diterpenoids in Rabdosia japonica var.glaucocalyx by HPLC-ESI-MS/MS and cluster analysis].

PubMed

Tian, Ting-Ting; Ma, Ying-Hua; Xie, Wei-Wei; Jin, Yi-Ran; Xu, Hui-Jun; Zhang, Lan-Tong; Du, Ying-Feng

2016-01-01

A quick HPLC-ESI-MS/MS method was established for simultaneous determination of four major diterpenoids in Rabdosia japonica var.glaucocalyx, including glaucocalyxin A, oridonin, hebeirubesensin and enmenol. Analysis was performed on an Agilent ZORBAX SB-C18(4.6 mm×250 mm, 5 μm ) column eluted in a gradient program with methanol and water. The flow rate was 0.8 mL•min⁻¹. Multiple reaction monitoring (MRM) scanning mode was performed in negative ion switching mode to apply for the quantitative determination. The calibration curves for the above four compounds were linear in corresponding injection amount. The average recoveries of the compounds ranged from 92.40% to 105.9%, with RSDs of 1.7%-6.5%. The method is simple, rapid, accurate with good repeatability, which can provide a reference for overcalling evaluation the quality of R. japonica var.glaucocalyx. The result of cluster analysis- showed that the quality of R. japonica glaucocalyx var. greatly varied between areas and parts. Copyright© by the Chinese Pharmaceutical Association.

The phase-space dependence of fast-ion interaction with tearing modes

DOE PAGES

Heidbrink, William W.; Bardoczi, Laszlo; Collins, Cami S.; ...

2018-03-19

Modulation of various neutral beam sources probes the interaction of fast ions with tearing modes (TM) in the DIII-D tokamak. As measured by electron cyclotron emission, the (m,n) = (2,1) tearing modes have an island width of ~8 cm and change phase 180 at the q = 2 surface. (Here, m is the poloidal mode number and n is the toroidal mode number.) Deuterium neutral beam injection by six sources with differing injection geometries produces the fast ions. To study the interaction in different parts of phase space, on successive discharges, one of the six sources is modulated at 20more » Hz to populate different fast-ion orbits. The modulation only changes the island width by a few millimeters, implying that any fast-ion effect on mode stability is below detection limits. When compared to the expected signals in the absence of TM-induced transport, both the average and modulated neutron signals deviate, implying that fast-ion transport occurs in much of phase space. Fast-ion D-α (FIDA) measurements detect reductions in signal at wavelengths that are sensitive to counter-passing ions. Neutral particle analyzer data imply poor confinement of trapped fast ions. Lastly, calculations of the expected fast-ion transport that use measured TM properties successfully reproduce the data.« less

EFFECTS OF AZADIRACHTIN ON CUTICULAR PROTEINS OF SPODOPTERA LITURA (LEPIDOPTERA: NOCTUIDAE) VIS-A-VIS THE MODES OF APPLICATION.

PubMed

Yooboon, T; Pluempanupat, W; Koul, Opender; Bullangpoti, V

2015-01-01

Azadirachtin is a known botanical insecticide with multiple modes of action. Whether these effects have any relation with the modes of application, specifically during ecdysis process, has been the objective of the present study and accordingly the impairment, if any, among cuticular proteins of Spodoptera litura (Fab.) was determined. Azadirachtin was applied topically, via injection or oral administration. Azadirachtin administered via injection and topical applications severely impaired the ecdysis by 86.67 and 80.0%, respectively. However, this impairment via oral administration was significantly lower (73.33%). Using SDS-PAGE, the cuticular proteins were determined for treated insects under all the three modes of application. In all cases 6 protein bands (MW 9-34 kDa) were identified using markers as standard. In all treatments 3 induced proteins (MW. ~16, 20 and 23 kDa) and 1 reduced protein (~19 kDa) were observed. In case of the topical treatment a different induced protein of ~18 kDa was identified. The change in cuticular proteins, their possible role in ecdysis impairment vis-a-vis the mode of application of azadirachtin is being correlated. This will help in understanding the mode-of-action at cuticular level and also will allow developing a suitable application strategy under field conditions in insect pest management.

The phase-space dependence of fast-ion interaction with tearing modes

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

Heidbrink, William W.; Bardoczi, Laszlo; Collins, Cami S.

Modulation of various neutral beam sources probes the interaction of fast ions with tearing modes (TM) in the DIII-D tokamak. As measured by electron cyclotron emission, the (m,n) = (2,1) tearing modes have an island width of ~8 cm and change phase 180 at the q = 2 surface. (Here, m is the poloidal mode number and n is the toroidal mode number.) Deuterium neutral beam injection by six sources with differing injection geometries produces the fast ions. To study the interaction in different parts of phase space, on successive discharges, one of the six sources is modulated at 20more » Hz to populate different fast-ion orbits. The modulation only changes the island width by a few millimeters, implying that any fast-ion effect on mode stability is below detection limits. When compared to the expected signals in the absence of TM-induced transport, both the average and modulated neutron signals deviate, implying that fast-ion transport occurs in much of phase space. Fast-ion D-α (FIDA) measurements detect reductions in signal at wavelengths that are sensitive to counter-passing ions. Neutral particle analyzer data imply poor confinement of trapped fast ions. Lastly, calculations of the expected fast-ion transport that use measured TM properties successfully reproduce the data.« less

Investigation of physical processes limiting plasma density in H-mode on DIII-D

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

Maingi, R.; Mahdavi, M.A.; Jernigan, T.C.

1996-12-01

A series of experiments was conducted on the DIII-D tokamak to investigate the physical processes which limit density in high confinement mode (H-mode) discharges. The typical H-mode to low confinement mode (L-mode) transition limit at high density near the empirical Greenwald density limit was avoided by divertor pumping, which reduced divertor neutral pressure and prevented formation of a high density, intense radiation zone (MARFE) near the X-point. It was determined that the density decay time after pellet injection was independent of density relative to the Greenwald limit and increased non-linearly with the plasma current. Magnetohydrodynamic (MHD) activity in pellet-fueled plasmasmore » was observed at all power levels, and often caused unacceptable confinement degradation, except when the neutral beam injected (NBI) power was {le} 3 MW. Formation of MARFEs on closed field lines was avoided with low safety factor (q) operation but was observed at high q, qualitatively consistent with theory. By using pellet fueling and optimizing discharge parameters to avoid each of these limits, an operational space was accessed in which density {approximately} 1.5 {times} Greenwald limit was achieved for 600 ms, and good H-mode confinement was maintained for 300 ms of the density flattop. More significantly, the density was successfully increased to the limit where a central radiative collapse was observed, the most fundamental density limit in tokamaks.« less

A sensitive method using SPME pre-concentration for the quantification of aromatic amines in indoor air.

PubMed

Lucaire, Vincent; Schwartz, Jean-Jacques; Delhomme, Olivier; Ocampo-Torres, Ruben; Millet, Maurice

2018-03-01

Monitoring the levels of aliphatic and aromatic amines (AA) in indoor air is important to protect human health because of exposure to these compounds through diet and inhalation. A sampling and analytical method using XAD-2 cartridges and gas chromatography coupled to mass spectrometry used for assessing 25 AA in different smoking and non-smoking indoor environment was developed. After sampling and delivering 1 m 3 of air (6-8 h sampling), an adsorbent was ultrasonically extracted with acetonitrile, concentrated to 1 mL and diluted in 25 mL of water (pH = 9; 5% NaCl), and then extracted for 40 min at 80 °C using a divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fiber and injected in a GC/MS system. With this method, 22 of the 25 AA can be analyzed with detection limits up to five times lower than that of classic liquid injection. Benzylamine, 3-aminophenol, and 4-aminophenol were not detected with the solid-phase micro-extraction (SPME) method. It can be assumed that aminophenols required a derivatization step for their analysis by GC as these molecules were not detected regardless of the injection mode used. Graphical abstract Analysis of aromatic amines in indoor air by SPME-GC/MS.

Optimization of programmed-temperature vaporization injection preparative capillary GC for compound specific radiocarbon analysis.

PubMed

Zhang, Xinyu; Zhao, Liang; Wang, Yexin; Xu, Yunping; Zhou, Liping

2013-07-01

Preparative capillary GC (PCGC) is a powerful tool for the separation and purification of compounds from any complex matrix, which can be used for compound-specific radiocarbon analysis. However, the effect of PCGC parameters on the trapping efficiency is not well understood. Here, we present a comprehensive study on the optimization of parameters based on 11 reference compounds with different physicochemical properties. Under the optimum conditions, the trapping efficiencies of these 11 compounds (including high-boiling-point n-hentriacontane and methyl lignocerate) are about 80% (60-89%). The isolation of target compounds from standard solutions, plant and soil samples demonstrates that our optimized method is applicable for different classes of compounds including n-alkanes, fatty acid esters, long-chain fatty alcohol esters, polycyclic aromatic hydrocarbons (PAHs) and steranes. By injecting 25 μL in large volume injection mode, over 100 μg, high purity (>90%) target compounds are harvested within 24 h. The recovery ranges of two real samples are about 70% (59.9-83.8%) and about 83% (77.2-88.5%), respectively. Compared to previous studies, our study makes significant improvement in the recovery of PCGC, which is important for its wide application in biogeochemistry, environmental sciences, and archaeology. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dual-Valve and Counter-Flow Surface Plasmon Resonance.

PubMed

Wang, Xiaoying; Zhou, Feimeng

2018-04-17

Two six-port injector valves and one selector valve commonly used in flow injection analysis are combined with a surface plasmon resonance (SPR) instrument wherein solutions introduced from the two inlets counter-flow inside the flow cell. The system is versatile as the same or different solutions can be rapidly and repeatedly introduced to the two fluidic channels in series or in parallel. Unlike most commercial SPR instruments employing a single injector valve, solutions separately injected from the two injector valves can be readily exchanged (<1 s) between the two channels. This new method, referred to as the alternate injection mode, not only saves analysis time but also facilitates efficient and facile surface reactions for ligand immobilization and prevents immobilized species from desorbing. These advantages are demonstrated with the measurements of binding of acetazolamide (222.2 Da) to histidine-tagged human carbonic anhydrase II (his-tagged HCA). Amine-containing residues of his-tagged HCA molecules tethered at Ni-nitrilotriacetic acid (NTA) sensors were rapidly cross-linked to the underlying carboxymethylated dextran. The higher ligand densities and more stable surfaces are essential for SPR detection of small molecule binding. In a different application, microglobulin solutions of increasing concentrations were introduced for continuous binding to the preimmobilized antibody. The kinetic and affinity measurements can be conducted without performing repeated dissociation and surface regeneration reactions.

Whispering gallery mode resonators for rapid label-free biosensing in small volume droplets.

PubMed

Wildgen, Sarah M; Dunn, Robert C

2015-03-23

Rapid biosensing requires fast mass transport of the analyte to the surface of the sensing element. To optimize analysis times, both mass transport in solution and the geometry and size of the sensing element need to be considered. Small dielectric spheres, tens of microns in diameter, can act as label-free biosensors using whispering gallery mode (WGM) resonances. WGM resonances are sensitive to the effective refractive index, which changes upon analyte binding to recognition sites on functionalized resonators. The spherical geometry and tens of microns diameter of these resonators provides an efficient target for sensing while their compact size enables detection in limited volumes. Here, we explore conditions leading to rapid analyte detection using WGM resonators as label-free sensors in 10 μL sample droplets. Droplet evaporation leads to potentially useful convective mixing, but also limits the time over which analysis can be completed. We show that active droplet mixing combined with initial binding rate measurements is required for accurate nanomolar protein quantification within the first minute following injection.

Sepsis and Inflammatory Response Mechanisms: An Activity Stress Model in Humans

DTIC Science & Technology

2001-01-31

anaerobic threshold yielded the reactions most typical of trauma. However, no mode of laboratory exercise induced a sustained and prolonged inflammatory...mobilization ....................................................................................... 9 8. Anaerobic threshold as a marker of the critical...after epmnephriei injection. Lymphocyte retention by lymph nodes, however, may contribute to post-injection lymphopenia. 8. Anaerobic Threshold as a

Nox Emission Reduction in Commercial Jets Through Water Injection

NASA Technical Reports Server (NTRS)

Balepin, Vladimir; Ossello, Chris; Snyder, Chris

2002-01-01

This paper discusses a method of the nitrogen oxides (NOx) emission reduction through the injection of water in commercial turbofan engines during the takeoff and climbout cycles. In addition to emission reduction, this method can significantly reduce turbine temperature during the most demanding operational modes (takeoff and climbout) and increase engine reliability and life.

Coherently wavelength injection-locking a 600-μm long cavity colorless laser diode for 16-QAM OFDM at 12 Gbit/s over 25-km SMF.

PubMed

Li, Yi-Cheng; Chi, Yu-Chieh; Cheng, Min-Chi; Lu, I-Cheng; Chen, Jason; Lin, Gong-Ru

2013-07-15

The coherent injection-locking and directly modulation of a long-cavity colorless laser diode with 1% end-facet reflectance and weak-resonant longitudinal modes is employed as an universal optical transmitter to demonstrated for optical 16-QAM OFDM transmission at 12 Gbit/s over 25 km in a DWDM-PON system. The optimized bias current of 30 mA (~1.5Ith) with corresponding extinction ratio (ER) of 6 dB and the external injection power of -9 dBm is (are) required for such a wavelength-locked universal transmitter to carry the 16-QAM and 122-subcarrier formatted OFDM and data-stream. By increasing external injection-locking from -9 dBm to 0 dBm, the peak-to-peak chirp of the OFDM data stream reduces from 7.7 to 5.4 GHz. The side mode suppression ratio (SMSR) of up to 50 dB is achieved with wider detuning range between -0.5 nm to 2.0 nm under an injection power of 0 dBm. By modulating such a colorless laser diode with an OFDM data stream of 122 subcarriers at a central carrier frequency of 1.5625 GHz and a total bandwidth of 3 GHz, the transmission data rate of up to 12 Gbit/s in standard single-mode fiber over 25 km is demonstrated to achieve an error vector magnitude (EVM) of 5.435%. Such a universal colorless DWDM-PON transmitter can deliver the optical OFDM data-stream at 12 Gbit/s QAM-OFDM data after 25-km transmission with a receiving power sensitivity of -7 dBm at BER of 3.6 × 10(-7) when pre-amplifying the OFDM data by 5 dB.

Experimental characterization of an all-optical wavelength converter of OFDM signals using two-mode injection-locking in a Fabry-Pérot laser.

PubMed

Dang, Juntao; Yi, Xingwen; Zhang, Jing; Ye, Taiping; Xu, Bo; Qiu, Kun

2016-07-25

While optical OFDM has been demonstrated for superior transmission performance, its analogue waveform in the time domain challenges many conventional all-optical wavelength converters (AOWC) that are needed for future flexible optical networks. There only exist a few reports on AOWC of OFDM signals, which are mainly based on the low-efficient four-wave mixing. In this paper, we propose an AOWC for OFDM signals by using two-mode injection-locking in a low-cost Fabry-Pérot laser. The control signal and the probe signal at a milliwatt power level are combined and injected into the FP laser. By a proper control, they can be injection-locked to two longitudinal modes in the FP laser and subsequently, the transmission of the probe signal is conditioned by the control signal. We conduct an experimental study on various aspects of this AOWC. Despite a vendor-specified electrical-to-optical (E/O) modulation bandwidth of 2.5 GHz, we find that the optical-to-optical (O/O) modulation bandwidth of AOWC is free from this limit and can be much wider. We examine the linear transfer curve of the AOWC by simply using the OFDM waveforms as the stimulus. The performance tolerance to the wavelength detuning and injected power ratio is also measured. The proposed AOWC can provide a linear transfer function from the control signal to the probe signal to support the random-fluctuated OFDM waveform. We also investigate the maximum capacity of the AOWC by using the adaptive bit-loading OFDM. Finally, we measure the power penalty after the AOWC at two different bit rates to show the tradeoff between the penalty and capacity.

Inter-comb synchronization by mode-to-mode locking

NASA Astrophysics Data System (ADS)

Chun, Byung Jae; Kim, Young-Jin; Kim, Seung-Woo

2016-08-01

Two combs of fiber femtosecond lasers are synchronized through the optical frequency reference created by injection-locking of a diode laser to a single comb mode. Maintaining a mHz-level narrow linewidth, the optical frequency reference permits two combs to be stabilized by mode-to-mode locking with a relative stability of 1.52  ×  10-16 at 10 s with a frequency slip of 2.46 mHz. This inter-comb synchronization can be utilized for applications such as dual-comb spectroscopy or ultra-short pulse synthesis without extra narrow-linewidth lasers.

Transport toward a well in highly heterogeneous aquifer

NASA Astrophysics Data System (ADS)

Di Dato, Mariaines; de Barros, Felipe P. J.; Bellin, Alberto; Fiori, Aldo

2017-04-01

Solute transport toward a well is a challenging subject in subsurface hydrology since the complexity of the mathematical model is tremendously increased by the non-uniformity of the mean flow and heterogeneity of the formation. Up to date, analytical solutions for such flow configurations are limited to low heterogeneous conditions. On the other hand, numerical simulations in 3D highly heterogeneous formations are computationally expensive and plagued by numerical errors. In this work we propose an analytical solution for the Breakthrough Curve (BTC) at the well for an instantaneous linear injection across the aquifer's thickness for any degree of heterogeneity of the porous medium. Our solution makes use of the Multi Indicator Model-Self Consistent Approximation (MIMSCA), by which the aquifer is conceptualized as an ensemble of blocks of constant hydraulic conductivity K randomly drawn from a lognormal distribution. In order to apply MIMSCA, we assume the flow as locally uniform, given that K is uniform within the block. With this approximation, the travel time to the well is equal to the superposition of the time spent by the solute particle within each block. We emphasize that, despite the approximations introduced, the model is able to reproduce the laboratory experiment of [1] without the need to fit any transport parameters. In this work, we present results for two different injection modes: a resident injection (e.g., residual DNAPL) and a flux proportional injection (e.g., leakage from a passive well). The proposed methodology allows to quantify the BTC at the well as a function of few parameters such as the injection mode and the statistical structure of the aquifer (geometric mean, variance and integral scale of the hydraulic conductivity field). Results illustrate that the release condition has a strong impact on the shape of the BTC. Furthermore, the difference between different injection modes increases with the heterogeneity of the K-field. The importance of the both injection mode and heterogeneity degree are also elucidated on the early and late solute arrival times at the well. Finally, we show how travel times become ergodic only for very thick aquifers, even in case of mild heterogeneity. We emphasize that the present framework has a practical validity, giving an affordable, although approximated, first estimation of mass arrival at an extraction well. References [1] Fernàndez-Garcia, D., T. H. Illangasekare, and H. Rajaram (2004), Conservative and sorptive forced-gradient and uniform flow tracer tests in a three-dimensional laboratory test aquifer, Water Resour. Res., 40, W10103, doi:10.1029/2004WR003112.

Operations of the External Conjugate-T Matching System for the A2 ICRH Antennas at JET

NASA Astrophysics Data System (ADS)

Monakhov, I.; Graham, M.; Blackman, T.; Mayoral, M.-L.; Nightingale, M.; Sheikh, H.; Whitehurst, A.

2009-11-01

The External Conjugate-T (ECT) matching system was successfully commissioned on two A2 ICRH antennas at JET in 2009. The system allows trip-free injection of RF power into ELMy H-mode plasmas in the 32-52 MHz band without antenna phasing restrictions. The ECT demonstrates robust and predictable performance and high load-tolerance during routine operations, injecting up to 4 MW average power into H-mode plasma with Type-I ELMs. The total power coupled to ELMy plasma by all the A2 antennas using the ECT and 3dB systems has been increased to 7 MW. Antenna arcing during ELMs has been identified as a new challenge to high-power ICRH operations in H-mode plasma. The implemented Advanced Wave Amplitude Comparison System (AWACS) has proven to be an efficient protection tool for the ECT scheme.

System Study: Residual Heat Removal 1998-2014

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

Schroeder, John Alton

2015-12-01

This report presents an unreliability evaluation of the residual heat removal (RHR) system in two modes of operation (low-pressure injection in response to a large loss-of-coolant accident and post-trip shutdown-cooling) at 104 U.S. commercial nuclear power plants. Demand, run hours, and failure data from fiscal year 1998 through 2014 for selected components were obtained from the Institute of Nuclear Power Operations (INPO) Consolidated Events Database (ICES). The unreliability results are trended for the most recent 10 year period, while yearly estimates for system unreliability are provided for the entire active period. No statistically significant increasing trends were identified in themore » RHR results. A highly statistically significant decreasing trend was observed for the RHR injection mode start-only unreliability. Statistically significant decreasing trends were observed for RHR shutdown cooling mode start-only unreliability and RHR shutdown cooling model 24-hour unreliability.« less

Operations of the External Conjugate-T Matching System for the A2 ICRH Antennas at JET

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

Monakhov, I.; Graham, M.; Blackman, T.

2009-11-26

The External Conjugate-T (ECT) matching system was successfully commissioned on two A2 ICRH antennas at JET in 2009. The system allows trip-free injection of RF power into ELMy H-mode plasmas in the 32-52 MHz band without antenna phasing restrictions. The ECT demonstrates robust and predictable performance and high load-tolerance during routine operations, injecting up to 4 MW average power into H-mode plasma with Type-I ELMs. The total power coupled to ELMy plasma by all the A2 antennas using the ECT and 3dB systems has been increased to 7 MW. Antenna arcing during ELMs has been identified as a new challengemore » to high-power ICRH operations in H-mode plasma. The implemented Advanced Wave Amplitude Comparison System (AWACS) has proven to be an efficient protection tool for the ECT scheme.« less

A novel liquid chromatography Orbitrap mass spectrometry method with full scan for simultaneous determination of multiple bioactive constituents of Shenkang injection in rat tissues: Application to tissue distribution and pharmacokinetic studies.

PubMed

Yang, Jie; Sun, Zhi; Li, Duolu; Duan, Fei; Li, Zhuolun; Lu, Jingli; Shi, Yingying; Xu, Tanye; Zhang, Xiaojian

2018-06-07

Shenkang injection is a traditional Chinese formula with good curative effect on chronic renal failure. In this paper, a novel, rapid and sensitive ultra high performance liquid chromatography coupled with Q Exactive hybrid quadrupole orbitrap high resolution accurate mass spectrometry was developed and validated for simultaneous determination of seven bioactive constituents of Shenkang injection in rat plasma and tissues after intravenous administration. Acetonitrile was used as protein precipitation agent in biological samples dispose with carbamazepine as internal standard. The chromatographic separation was carried out on a C 18 column with a gradient mobile phase consisting of acetonitrile and water (containing 0.1% formic acid). The MS analysis was performed in the full scan positive and negative ion mode. The lower limits of quantification for the seven analytes in rat plasma and tissues were 0.1-10 ng/mL. The validated method was successfully applied to tissue distribution and pharmacokinetic studies of Shenkang injection after intravenous administration. The results of the tissue distribution study showed that the high concentration of seven constituents were primarily in the kidney tract. This is the first time to report the application of Q-Orbitrap with full scan mass spectrometry in tissue distribution and pharmacokinetic studies of Shenkang injection. This article is protected by copyright. All rights reserved.

Plan for radionuclide tracer studies of the residence time distribution in the Wilsonville dissolver and preheater

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

Jolley, R.L.; Begovich, J.M.; Brashear, H.R.

1983-12-01

Stimulus-response measurements using radiotracers to measure residence time distribution (RTD) and hydrodynamic parameters for the preheaters and dissolvers at the Ft. Lewis Solvent Refined Coal (SRC) and the Exxon Donor Solvent (EDS) coal conversion pilot plants are reviewed. A plan is also presented for a series of radioactive tracer studies proposed for the Advanced Coal Liquefaction Facility at Wilsonville, Alabama, to measure the RTD for the preheater and dissolvers in the SRC-I mode. The tracer for the gas phase will be /sup 133/Xe, and /sup 198/Au (on carbonized resin or as an aqueous colloidal suspension) will be used as themore » slurry tracer. Four experimental phases are recommended for the RTD tracer studies: (1) preheater; (2) dissolver with 100% takeoff; (3) dissolver with 100% takeoff and solids withdrawal; and (4) dissolver with 50% takeoff. Eighteen gas-tracer and 22 liquid-tracer injections are projected to accomplish the four experimental phases. Two to four tracer injections are projected for preliminary tests to ensure the capability of safe injection of the radiotracers and the collection of statistically significant data. A complete projected cost and time schedule is provided, including procurement of necessary components, preparation of the radiotracers, assembly and testing of tracer injection apparatus and detection systems, onsite work and tracer injections, laboratory experimentation, data analysis, and report writing.« less

Off-axis fishbone-like instability and excitation of resistive wall modes in JT-60U and DIII-D

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

Okabayashi, M.; Solomon, W. M.; Budny, R. V.

2011-05-15

An energetic-particle (EP)-driven ''off-axis-fishbone-like mode (OFM)'' often triggers a resistive wall mode (RWM) in JT-60U and DIII-D devices, preventing long-duration high-{beta}{sub N} discharges. In these experiments, the EPs are energetic ions (70-85 keV) injected by neutral beams to produce high-pressure plasmas. EP-driven bursting events reduce the EP density and the plasma rotation simultaneously. These changes are significant in high-{beta}{sub N} low-rotation plasmas, where the RWM stability is predicted to be strongly influenced by the EP precession drift resonance and by the plasma rotation near the q=2 surface (kinetic effects). Analysis of these effects on stability with a self-consistent perturbation tomore » the mode structure using the MARS-K code showed that the impact of EP losses and rotation drop is sufficient to destabilize the RWM in low-rotation plasmas, when the plasma rotation normalized by Alfven frequency is only a few tenths of a percent near the q=2 surface. The OFM characteristics are very similar in JT-60U and DIII-D, including nonlinear mode evolution. The modes grow initially like a classical fishbone, and then the mode structure becomes strongly distorted. The dynamic response of the OFM to an applied n=1 external field indicates that the mode retains its external kink character. These comparative studies suggest that an energetic particle-driven 'off-axis-fishbone-like mode' is a new EP-driven branch of the external kink mode in wall-stabilized plasmas, analogous to the relationship of the classical fishbone branch to the internal kink mode.« less

Mode selection in square resonator microlasers for widely tunable single mode lasing.

PubMed

Tang, Ming-Ying; Sui, Shao-Shuai; Yang, Yue-De; Xiao, Jin-Long; Du, Yun; Huang, Yong-Zhen

2015-10-19

Mode selection in square resonator semiconductor microlasers is demonstrated by adjusting the width of the output waveguide coupled to the midpoint of one side. The simulation and experimental results reveal that widely tunable single mode lasing can be realized in square resonator microlasers. Through adjusting the width of the output waveguide, the mode interval of the high-Q modes can reach four times of the longitudinal mode interval. Therefore, mode hopping can be efficiently avoided and the lasing wavelength can be tuned continuously by tuning the injection current. For a 17.8-μm-side-length square microlaser with a 1.4-μm-width output waveguide, mode-hopping-free single-mode operation is achieved with a continuous tuning range of 9.2 nm. As a result, the control of the lasing mode is realized for the square microlasers.

Linear Stability Analysis of Gravitational Effects on a Low-Density Gas Jet Injected into a High-Density Medium

NASA Technical Reports Server (NTRS)

Lawson, Anthony L.; Parthasarathy, Ramkumar N.

2005-01-01

The objective of this study was to determine the effects of buoyancy on the absolute instability of low-density gas jets injected into high-density gas mediums. Most of the existing analyses of low-density gas jets injected into a high-density ambient have been carried out neglecting effects of gravity. In order to investigate the influence of gravity on the near-injector development of the flow, a spatio-temporal stability analysis of a low-density round jet injected into a high-density ambient gas was performed. The flow was assumed to be isothermal and locally parallel; viscous and diffusive effects were ignored. The variables were represented as the sum of the mean value and a normal-mode small disturbance. An ordinary differential equation governing the amplitude of the pressure disturbance was derived. The velocity and density profiles in the shear layer, and the Froude number (signifying the effects of gravity) were the three important parameters in this equation. Together with the boundary conditions, an eigenvalue problem was formulated. Assuming that the velocity and density profiles in the shear layer to be represented by hyperbolic tangent functions, the eigenvalue problem was solved for various values of Froude number. The Briggs-Bers criterion was combined with the spatio-temporal stability analysis to determine the nature of the absolute instability of the jet whether absolutely or convectively unstable. The roles of the density ratio, Froude number, Schmidt number, and the lateral shift between the density and velocity profiles on the absolute instability of the jet were determined. Comparisons of the results with previous experimental studies show good agreement when the effects of these variables are combined together. Thus, the combination of these variables determines how absolutely unstable the jet will be.

Three Dimensional Numerical Simulation of Rocket-based Combined-cycle Engine Response During Mode Transition Events

NASA Technical Reports Server (NTRS)

Edwards, Jack R.; McRae, D. Scott; Bond, Ryan B.; Steffan, Christopher (Technical Monitor)

2003-01-01

The GTX program at NASA Glenn Research Center is designed to develop a launch vehicle concept based on rocket-based combined-cycle (RBCC) propulsion. Experimental testing, cycle analysis, and computational fluid dynamics modeling have all demonstrated the viability of the GTX concept, yet significant technical issues and challenges still remain. Our research effort develops a unique capability for dynamic CFD simulation of complete high-speed propulsion devices and focuses this technology toward analysis of the GTX response during critical mode transition events. Our principal attention is focused on Mode 1/Mode 2 operation, in which initial rocket propulsion is transitioned into thermal-throat ramjet propulsion. A critical element of the GTX concept is the use of an Independent Ramjet Stream (IRS) cycle to provide propulsion at Mach numbers less than 3. In the IRS cycle, rocket thrust is initially used for primary power, and the hot rocket plume is used as a flame-holding mechanism for hydrogen fuel injected into the secondary air stream. A critical aspect is the establishment of a thermal throat in the secondary stream through the combination of area reduction effects and combustion-induced heat release. This is a necessity to enable the power-down of the rocket and the eventual shift to ramjet mode. Our focus in this first year of the grant has been in three areas, each progressing directly toward the key initial goal of simulating thermal throat formation during the IRS cycle: CFD algorithm development; simulation of Mode 1 experiments conducted at Glenn's Rig 1 facility; and IRS cycle simulations. The remainder of this report discusses each of these efforts in detail and presents a plan of work for the next year.

Pressurized capillary electrochromatographic analysis of water-soluble vitamins by combining with on-line concentration technique.

PubMed

Jia, Li; Liu, Yaling; Du, Yanyan; Xing, Da

2007-06-22

A pressurized capillary electrochromatography (pCEC) system was developed for the separation of water-soluble vitamins, in which UV absorbance was used as the detection method and a monolithic silica-ODS column as the separation column. The parameters (type and content of organic solvent in the mobile phase, type and concentration of electrolyte, pH of the electrolyte buffer, applied voltage and flow rate) affecting the separation resolution were evaluated. The combination of two on-line concentration techniques, namely, solvent gradient zone sharpening effect and field-enhanced sample stacking, was utilized to improve detection sensitivity, which proved to be beneficial to enhance the detection sensitivity by enabling the injection of large volumes of samples. Coupling electrokinetic injection with the on-line concentration techniques was much more beneficial for the concentration of positively charged vitamins. Comparing with the conventional injection mode, the enhancement in the detection sensitivities of water-soluble vitamins using the on-line concentration technique is in the range of 3 to 35-fold. The developed pCEC method was applied to evaluate water-soluble vitamins in corns.

Reduction of matrix effects in inductively coupled plasma mass spectrometry by flow injection with an unshielded torch.

PubMed

Gross, Cory T; McIntyre, Sally M; Houk, R S

2009-06-15

Solution samples with matrix concentrations above approximately 0.1% generally present difficulties for analysis by inductively coupled plasma mass spectrometry (ICP-MS) because of cone clogging and matrix effects. Flow injection (FI) is coupled to ICP-MS to reduce deposition from samples such as 1% sodium salts (as NaCl) and seawater (approximately 3% dissolved salts). Surprisingly, matrix effects are also less severe during flow injection, at least for some matrix elements on the particular instrument used. Sodium chloride at 1% Na and undiluted seawater cause only 2 to 29% losses of signal for typical analyte elements. A heavy matrix element (Bi) at 0.1% also induces only approximately 14% loss of analyte signal. However, barium causes a much worse matrix effect, that is, approximately 90% signal loss at 5000 ppm Na. Also, matrix effects during FI are much more severe when a grounded metal shield is inserted between the load coil and the torch, which is the most common mode of operation for the particular ICP-MS device used.

Determination of Noncovalent Binding Using a Continuous Stirred Tank Reactor as a Flow Injection Device Coupled to Electrospray Ionization Mass Spectrometry

NASA Astrophysics Data System (ADS)

Santos, Inês C.; Waybright, Veronica B.; Fan, Hui; Ramirez, Sabra; Mesquita, Raquel B. R.; Rangel, António O. S. S.; Fryčák, Petr; Schug, Kevin A.

2015-07-01

Described is a new method based on the concept of controlled band dispersion, achieved by hyphenating flow injection analysis with ESI-MS for noncovalent binding determinations. A continuous stirred tank reactor (CSTR) was used as a FIA device for exponential dilution of an equimolar host-guest solution over time. The data obtained was treated for the noncovalent binding determination using an equimolar binding model. Dissociation constants between vancomycin and Ac-Lys(Ac)-Ala-Ala-OH peptide stereoisomers were determined using both the positive and negative ionization modes. The results obtained for Ac- L-Lys(Ac)- D-Ala- D-Ala (a model for a Gram-positive bacterial cell wall) binding were in reasonable agreement with literature values made by other mass spectrometry binding determination techniques. Also, the developed method allowed the determination of dissociation constants for vancomycin with Ac- L-Lys(Ac)- D-Ala- L-Ala, Ac- L-Lys(Ac)- L-Ala- D-Ala, and Ac- L-Lys(Ac)- L-Ala- L-Ala. Although some differences in measured binding affinities were noted using different ionization modes, the results of each determination were generally consistent. Differences are likely attributable to the influence of a pseudo-physiological ammonium acetate buffer solution on the formation of positively- and negatively-charged ionic complexes.

Starting Processes of High Contraction Ratio Scramjet Inlets

DTIC Science & Technology

2012-01-01

shortly before injection, at which point the boxes were switched to relative mode via the “ Taka Taka ” box, shown on Fig. 22. This absolute mode...camera used for the Schlieren visualisation, as well as the trigger for the 32 channel data acquisition system used. Figure 22: Taka ... taka box, used to manipulate the resistance mode during testing Figure 23: Typical raw thin film array signal, showing both absolute and relative

Identification of di(ethylhexyl) phthalate as impurity in the analysis by using chromatography gas tandem mass spectrometry

NASA Astrophysics Data System (ADS)

Pusfitasari, Eka Dian; Hendarsyah, Hendris; Salahuddin, Ariani, Novita

2017-01-01

Di(ethylhexyl) phthalate (DEHP) is a plasticizer commonly used in plastics. Physically DEHP has a low vapor pressure. DEHP can seep into the liquid in direct contact with the plastic wrapping materials, and typically can occur rapidly if extractable into food or non-polar solvents, such as oil, once the food is packaged in PVC packaging materials. DEHP has been analyzed by using gas chromatography which has a high sensitivity level. If the equipment used for the analysis is made from plastic containing DEHP, then it may be possible that DEHP can be extracted and appear on the outcome of the injection. It can interfere with the process of analysis, especially for the analysis of food samples. This study has identified the present of DEHP in the blank injection performed by Gas Chromatography tandem Mass Spectrometry with Selected Ion Monitoring mode (SIM). Researchers are required to verify whether the gas chromatographic system used is ready for the analysis process. In addition, the comparison and calculation of the intensity of the ion fragmentation spectra generated by mass spectrometry detector can be used for the qualitative determination to ensure the presence of the target compound. In this study is also discussed the differences between the high-intensity fragmentation of DEHP and dioctyl phthalate (DOP).

Stable Spheromaks with Profile Control

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

Fowler, T K; Jayakumar, R

A spheromak equilibrium with zero edge current is shown to be stable to both ideal MHD and tearing modes that normally produce Taylor relaxation in gun-injected spheromaks. This stable equilibrium differs from the stable Taylor state in that the current density j falls to zero at the wall. Estimates indicate that this current profile could be sustained by non-inductive current drive at acceptable power levels. Stability is determined using the NIMROD code for linear stability analysis. Non-linear NIMROD calculations with non-inductive current drive could point the way to improved fusion reactors.

Characterization of a Heated Liquid Jet in Crossflow

NASA Astrophysics Data System (ADS)

Wiest, Heather K.

The liquid jet in crossflow (LJICF) is a widely utilized fuel injection method for airbreathing propulsion devices such as low NO x gas turbine combustors, turbojet afterburners, scramjet/ramjet engines, and rotating detonation engines (RDE's). This flow field allows for efficient fuel-air mixing as aerodynamic forces from the crossflow augment atomization. Additionally, increases in the thermal demands of advanced aeroengines necessitates the use of fuel as a primary coolant. The resulting higher fuel temperatures can cause flash atomization of the liquid fuel as it is injected into a crossflow, potentially leading to a large reduction in the jet penetration. While many experimental works have characterized the overall atomization process of a room temperature liquid jet in an ambient temperature and pressure crossflow, the aggressive conditions associated with flash atomization especially in an air crossflow with elevated temperatures and pressures have been less studied in the community. A successful test campaign was conducted to study the effects of fuel temperature on a liquid jet injected transversely into a steady air crossflow at ambient as well as elevated temperature and pressure conditions. Modifications were made to an existing optically accessible rig, and a new fuel injector was designed for this study. Backlit imaging was utilized to record changes in the overall spray characteristics and jet trajectory as fuel temperature and crossflow conditioners were adjusted. Three primary analysis techniques were applied to the heated LJICF data: linear regression of detected edges to determine trajectory correlations, exploratory study of pixel intensity variations both temporally as well as spatially, and modal decomposition of the data. The overall objectives of this study was to assess the trajectory, breakup, and mixing of the LJICF undery varying jet and crossflow conditions, develop a trajectory correlation to predict changes in jet penetration due to fuel temperature increases, and characterize the changes in underlying physics in the LJICF flow field. Based on visual inspection, the increase in fuel temperature leads to a finer and denser fuel spray. With increasingly elevated liquid temperatures, the penetration of the jet typically decreases. At or near flashing conditions, the jet had a tendency to penetrate upstream before bending over in the crossflow as well as experiences a rapid expansion causing the jet column to increase in width. Two trajectory correlations were determined, one for each set of crossflow conditions, based on normalized axial distance, normalized liquid viscosity, and normalized jet diameter as liquid is vaporized. The pixel intensity analysis showed that the highest temperature jet in the ambient temperature and pressure crossflow exhibited periodic behavior that was also found using various modal techniques including proper orthogonal decomposition and dynamic mode decomposition. Dominant frequencies determined for most test cases were associated with the bulk or flapping motion of the jet. Most notably, the DMD analysis in this study was successful in identifying robust modes across different subgroupings of the data even though the modes identified were not the highest power modes in each DMD spectrum.

Analysis of solvent dyes in refined petroleum products by electrospray ionization mass spectrometry

USGS Publications Warehouse

Rostad, C.E.

2010-01-01

Solvent dyes are used to color refined petroleum products to enable differentiation between gasoline, diesel, and jet fuels. Analysis for these dyes in the hydrocarbon product is difficult due to their very low concentrations in such a complex matrix. Flow injection analysis/electrospray ionization/mass spectrometry in both negative and positive mode was used to optimize ionization of ten typical solvent dyes. Samples of hydrocarbon product were analyzed under similar conditions. Positive electrospray ionization produced very complex spectra, which were not suitably specific for targeting only the dyes. Negative electrospray ionization produced simple spectra because aliphatic and aromatic moieties were not ionized. This enabled screening for a target dye in samples of hydrocarbon product from a spill.

FDDI network test adaptor error injection circuit

NASA Technical Reports Server (NTRS)

Eckenrode, Thomas (Inventor); Stauffer, David R. (Inventor); Stempski, Rebecca (Inventor)

1994-01-01

An apparatus for injecting errors into a FDDI token ring network is disclosed. The error injection scheme operates by fooling a FORMAC into thinking it sent a real frame of data. This is done by using two RAM buffers. The RAM buffer normally accessed by the RBC/DPC becomes a SHADOW RAM during error injection operation. A dummy frame is loaded into the shadow RAM in order to fool the FORMAC. This data is just like the data that would be used if sending a normal frame, with the restriction that it must be shorter than the error injection data. The other buffer, the error injection RAM, contains the error injection frame. The error injection data is sent out to the media by switching a multiplexor. When the FORMAC is done transmitting the data, the multiplexor is switched back to the normal mode. Thus, the FORMAC is unaware of what happened and the token ring remains operational.

Supermode-noise-free eighth-order femtosecond soliton from a backward dark-optical-comb-injection mode-locked semiconductor optical amplifier fiber laser.

PubMed

Lin, Gong-Ru; Pan, Ci-Ling; Chiu, I-Hsiang

2006-03-15

A backward dark-optical-comb-injection mode-locked semiconductor optical amplifier fiber laser (SOAFL) with a femtosecond pulse width and an ultrahigh supermode-noise suppressing ratio (SMSR) is primarily demonstrated. The mode-locked SOAFL pulse with a spectral linewidth of 0.45 nm is shortened from 15 to 8.6 ps under chirp compensation in a 420 m long dispersion-compensated fiber, corresponding to a time-bandwidth product of 0.48. The eighth-order soliton is obtained by the nonlinearly soliton's compression of the chirp-compensated SOAFL pulse in a 112 m long single-mode fiber at an input peak power of 51 W, providing the pulse width, the linewidth, and the nearly transform-limited time-bandwidth product are <200 fs, 13.8 nm, and 0.34, respectively. The phase noise and integrated timing jitter at an offset frequency below 1 MHz are -105 dBc/Hz and 0.8 ps, respectively. An ultrahigh pulse-compression ratio of 43 and a SMSR of 87 dB for the eighth-order SOAFL soliton are reported.

Pre-injection brine production for managing pressure in compartmentalized CO₂ storage reservoirs

DOE PAGES

Buscheck, Thomas A.; White, Joshua A.; Chen, Mingjie; ...

2014-12-31

We present a reservoir management approach for geologic CO₂ storage that combines CO₂ injection with brine extraction. In our approach, dual-mode wells are initially used to extract formation brine and subsequently used to inject CO₂. These wells can also be used to monitor the subsurface during pre-injection brine extraction so that key data is acquired and analyzed prior to CO₂ injection. The relationship between pressure drawdown during pre-injection brine extraction and pressure buildup during CO₂ injection directly informs reservoir managers about CO₂ storage capacity. These data facilitate proactive reservoir management, and thus reduce costs and risks. The brine may bemore » used directly as make-up brine for nearby reservoir operations; it can also be desalinated and/or treated for a variety of beneficial uses.« less

Assessment of the ion-trap mass spectrometer for routine qualitative and quantitative analysis of drugs of abuse extracted from urine.

PubMed

Vorce, S P; Sklerov, J H; Kalasinsky, K S

2000-10-01

The ion-trap mass spectrometer (MS) has been available as a detector for gas chromatography (GC) for nearly two decades. However, it still occupies a minor role in forensic toxicology drug-testing laboratories. Quadrupole MS instruments make up the majority of GC detectors used in drug confirmation. This work addresses the use of these two MS detectors, comparing the ion ratio precision and quantitative accuracy for the analysis of different classes of abused drugs extracted from urine. Urine specimens were prepared at five concentrations each for amphetamine (AMP), methamphetamine (METH), benzoylecgonine (BZE), delta9-carboxy-tetrahydrocannabinol (delta9-THCCOOH), phencyclidine (PCP), morphine (MOR), codeine (COD), and 6-acetylmorphine (6-AM). Concentration ranges for AMP, METH, BZE, delta9-THCCOOH, PCP, MOR, COD, and 6-AM were 50-2500, 50-5000, 15-800, 1.5-65, 1-250, 500-32000, 250-21000, and 1.5-118 ng/mL, respectively. Sample extracts were injected into a GC-quadrupole MS operating in selected ion monitoring (SIM) mode and a GC-ion-trap MS operating in either selected ion storage (SIS) or full scan (FS) mode. Precision was assessed by the evaluation of five ion ratios for n = 15 injections at each concentration using a single-point calibration. Precision measurements for SIM ion ratios provided coefficients of variation (CV) between 2.6 and 9.8% for all drugs. By comparison, the SIS and FS data yielded CV ranges of 4.0-12.8% and 4.0-11.2%, respectively. The total ion ratio failure rates were 0.2% (SIM), 0.7% (SIS), and 1.2% (FS) for the eight drugs analyzed. Overall, the SIS mode produced stable, comparable mean ratios over the concentration ranges examined, but had greater variance within batch runs. Examination of postmortem and quality-control samples produced forensically accurate quantitation by SIS when compared to SIM. Furthermore, sensitivity of FS was equivalent to SIM for all compounds examined except for 6-AM.

Changes in B-mode ultrasound echo intensity following injection of bupivacaine hydrochloride to rat hind limb muscles in relation to histologic changes.

PubMed

Fujikake, T; Hart, R; Nosaka, Kazunori

2009-04-01

This study tested the hypothesis that infiltration of inflammatory cells in muscle fibers would increase echo intensity (image brightness) of B-mode ultrasound images. Bupivacaine hydrochloride (BPVC) or saline solution (SAL) was injected to the tibialis anterior (TA) muscles of 14- to 23-wk-old male Wistar rats. Ultrasound images were taken from the muscles before and at 0, 2, 4, 6, 9, 12, 24, 48, 72, 120, 168 and 336 h after the injection and analyzed for the echo intensity (echogenicity) expressed as the mean value of image pixel value of a region-of-interest. Changes in the echo intensity were compared between BPVC-injected and control or SAL-injected muscles. In the subsequent study, rats (n = 2 per time point) were sacrificed after taking ultrasound image at 0, 2, 6, 12, 24, 48 and 168 h after BPVC injection to the right TA and SAL injection to the left TA to observe histologic changes under a light microscope and the relationship between echo intensity and inflammatory cells was assessed. No significant changes in echo intensity were observed for the control, but BPVC induced significant (p < 0.05) increases in the echo intensity peaking 0 to 24 h postinjection. SAL also increased echo intensity immediately after injection but returned to the baseline by 24 h postinjection. The time course of changes in the echo intensity did not match with the time course of increases in inflammatory cells in the muscle. It is concluded that infiltration of inflammatory cells is not a direct cause of the increased echo intensity.

Analyses of Injection-Coupled Combustion Instability from J-2X Gas Generator Development

NASA Technical Reports Server (NTRS)

Hulka, James R.; Kenny, R. Jeremy; Protz, Chris; Casiano, Matthew

2011-01-01

During development of the gas generator for the liquid oxygen/liquid hydrogen propellant J-2X rocket engine, combustion instabilities were observed near the frequency of the first longitudinal acoustic mode of the hot gas combustion chamber duct. These instabilities were similar to intermediate-frequency or buzz-type instabilities as described in historical programs, except for several aspects: 1) the frequencies were low, in the realm of chug; 2) at times the instability oscillation amplitudes were quite large, with peak-to-peak amplitudes exceeding 50% of the mean chamber pressure along with the appearance of harmonics; 3) the chamber excitation was related to but not exactly at the first longitudinal combustion chamber acoustic mode; and 4) the injector provided mass flow rate oscillations induced by capacitance and inertance effects in the injector rather than by organ pipe resonances of the coaxial oxidizer posts. This type of combustion instability is referred to as "injection coupling" because one critical driving source of the instability is mass flow rate oscillations from the injector. However, the type of injection coupling observed here is different than observed in previous instances of buzz instability with coaxial injectors, because of the lower frequencies and lack of influence from the oxidizer post organ pipe resonances. Test data and preliminary analyses of the initial combustion instabilities were presented in several papers at the 5th Liquid Propulsion Subcommittee meeting. Since that time, additional hot-fire tests with several new hardware configurations have been conducted, and additional analyses have been completed. The analytical models described in previous papers have been updated to include the influences of new geometrical configurations, including a different oxidizer injector manifold configuration and a branch pipe in the hot gas duct that supplies gaseous helium during the start transient to pre-spin the turbine. In addition, the analysis methodology has been revisited to evaluate the potential influence of a combustion response as well as an injection response.

Observation of Beam-driven Modes during Neutral Beam Heating on the National Spherical Torus Experiment

NASA Astrophysics Data System (ADS)

Fredrickson, E. D.

2001-10-01

Multiple, coherent modes at frequencies up to the deuterium ion cyclotron frequency are observed during neutral beam injection heating of the National Spherical Torus Experiment (NSTX). NSTX plasmas are heated with up to 5 MW of deuterium neutral beam injection (NBI) power at a full energy of 80 kV. This gives a neutral beam ion velocity of ≈ 2.8 x 10^6 m/s, which is ≈ 3 V_Alfvén. The modes are seen in the frequency range of ≈ 0.4 MHz to ≈ 2.5 MHz. They are the first experimental observation of compressional Alfvén eigenmodes (CAE). The modes are excited by a resonant interaction with the non-Maxwellian, anisotropic ion distribution of the energetic beam ions and localized in an effective potential well of the form (m/r)^2 - (ω/V_Alfvén)^2. The resonance condition for the beam ions is approximately ω \\cal L ω_ci k_allel V_fast = 0, and the ``bump-on-tail" is in the perpendicular energy distribution resulting from the injection geometry (R_tan=50-70 cm, R_0=85 cm) and large orbit size (B_T=0.3-0.45 T, a=68 cm) for the beam ions. The modes are predicted to be localized on the low field side of the plasma, towards the plasma edge.(S.M. Mahajon , D.W. Ross, Phys. Fluids 26 (1983) 2561.)(B. Coppi, S. Cowley, R. Kulsrud, P. Detragiache, and F. Pegoraro, Phys. Fluids 29, (1986) 4060.)(Gorelenkov N.N., Cheng C.Z., Nucl. Fusion 35, (1995), pp 1743-1752.) The parametric scaling of the mode frequency with density and magnetic field is consistent with Alfvénic modes. The complex structure of the multiple frequency peaks is qualitatively consistent with predictions of CAE mode theories, although to date the modeling has been done in a simple geometry. There has been no observation of enhanced beam ion loss associated with the mode activity. Rather the presence of the modes is suspected to enhance the transfer of energy from the fast ions to the thermal ions or electrons. The drive for the mode is relatively strong, γ/ω ≈ 0.1 - 0.5 %, and the wave damping is thought to be electron Landau damping or stochastic damping on the thermal ions.(D. Gates, R. White, (submitted to Phys. Rev. Lett. May 2001).)

Active stabilization of a diode laser injection lock.

PubMed

Saxberg, Brendan; Plotkin-Swing, Benjamin; Gupta, Subhadeep

2016-06-01

We report on a device to electronically stabilize the optical injection lock of a semiconductor diode laser. Our technique uses as discriminator the peak height of the laser's transmission signal on a scanning Fabry-Perot cavity and feeds back to the diode current, thereby maintaining maximum optical power in the injected mode. A two-component feedback algorithm provides constant optimization of the injection lock, keeping it robust to slow thermal drifts and allowing fast recovery from sudden failures such as temporary occlusion of the injection beam. We demonstrate the successful performance of our stabilization method in a diode laser setup at 399 nm used for laser cooling of Yb atoms. The device eases the requirements on passive stabilization and can benefit any diode laser injection lock application, particularly those where several such locks are employed.

Determination of acrylamide in drinking water by large-volume direct injection and ion-exclusion chromatography-mass spectrometry.

PubMed

Cavalli, S; Polesello, S; Saccani, G

2004-06-11

Acrylamide, a known neurotoxin and putative human carcinogen, has been included among the substances to be monitored in drinking water according to the European Union Directive 98/83 on potable water. This paper reports a new method based on the combination of ion-exclusion chromatographic separation and MS detection. Samples of drinking water have been directly injected in the microbore ICE-AS1 column and detected in the selected-ion monitoring mode by a single quadrupole system with electrospray ionization. Chromatographic conditions, such as eluent composition and flow rate, have been optimized by a central composite design experiment. Statistical analysis of data showed that the amount of acetonitrile fraction in the eluent mixture, composed by acetonitrile and formic acid solution, is the variable that most influences retention of the acrylamide peak. After optimization of MS detection parameters, this method has been validated for spiked drinking water samples. The effect of large-volume injection (up to 500 microl) has been also explored. Linearity was evaluated from 0.5 to 5 microg l(-1). Repeatability, expressed as R.S.D., was 16 and 12% at 0.5 and 1 microg l(-1) respectively. The limit of detection was 0.20 ppb with 500 microl injection volume.

[Matrix effect and application of field-amplified sample injection in the analysis of four tetracyclines in waters by capillary electrohoresis].

PubMed

2014-08-01

The system abilities of two chromatographic techniques, capillary electrophoresis (CE) and high performance liquid chromatography (HPLC), were compared for the analysis of four tetracyclines (tetracycline, chlorotetracycline, oxytetracycline and doxycycline). The pH, concentration of background electrolyte (BGE) were optimized for the analysis of the standard mixture sample, meanwhile, the effects of separation voltage and water matrix (pH value and hardness) effects were investigated. In hydrodynamic injection (HDI) mode, a good quantitative linearity and baseline separation within 9. 0 min were obtained for the four tetracyclines at the optimal conditions; the analytical time was about half of that of HPLC. The limits of detection (LODs) were in the range of 0. 28 - 0. 62 mg/L, and the relative standard deviations (RSDs) (n= 6) of migration time and peak area were 0. 42% - 0. 56% and 2. 24% - 2. 95%, respectively. The obtained recoveries spiked in tap water and fishpond water were at the ranges of 96. 3% - 107. 2% and 87. 1% - 105. 2%, respectively. In addition, the stacking method, field-amplified sample injection (FASI), was employed to improve the sensitivity, and the LOD was down to the range of 17.8-35.5 μg/L. With FASI stacking, the RSDs (n=6) of migration time and peak area were 0. 85%-0. 95% and 1. 69%-3.43%, respectively. Due to the advantages of simple sample pretreatment and fast speed, CE is promising in the analysis of the antibiotics in environmental water.

Analysis of iodinated haloacetic acids in drinking water by reversed-phase liquid chromatography/electrospray ionization/tandem mass spectrometry with large volume direct aqueous injection.

PubMed

Li, Yongtao; Whitaker, Joshua S; McCarty, Christina L

2012-07-06

A large volume direct aqueous injection method was developed for the analysis of iodinated haloacetic acids in drinking water by using reversed-phase liquid chromatography/electrospray ionization/tandem mass spectrometry in the negative ion mode. Both the external and internal standard calibration methods were studied for the analysis of monoiodoacetic acid, chloroiodoacetic acid, bromoiodoacetic acid, and diiodoacetic acid in drinking water. The use of a divert valve technique for the mobile phase solvent delay, along with isotopically labeled analogs used as internal standards, effectively reduced and compensated for the ionization suppression typically caused by coexisting common inorganic anions. Under the optimized method conditions, the mean absolute and relative recoveries resulting from the replicate fortified deionized water and chlorinated drinking water analyses were 83-107% with a relative standard deviation of 0.7-11.7% and 84-111% with a relative standard deviation of 0.8-12.1%, respectively. The method detection limits resulting from the external and internal standard calibrations, based on seven fortified deionized water replicates, were 0.7-2.3 ng/L and 0.5-1.9 ng/L, respectively. Copyright © 2012 Elsevier B.V. All rights reserved.

Theoretical model for a thin cylindrical film optical fiber fluorosensor

NASA Technical Reports Server (NTRS)

Egalon, Claudio O.; Rogowski, Robert S.

1992-01-01

The analytical treatment of power efficiency (P(eff) is undertaken for the case of a positively guiding optical fiber with a thin-film source distributed in the core-cladding interface. The approach adopts the exact solution of the cylindrical optical fiber with an infinite cladding to account for differences between the indices of refraction of the core and the cladding. The excitation of low-loss leaky modes by the cladding is ignored, and only the injection by the evanescent field is considered. The formulas permit the analysis of the power-injection efficiency of fibers with arbitrary differences in indices of refraction. P(eff) does not always increase with V number, but rather varies slightly with wavelength and fiber-core radius and varies significantly with the difference in the indices of refraction. The theoretical results of the work are of interest for designing an atomic-O chemical sensor based on evanescent-wave coupling.

High performance mode locking characteristics of single section quantum dash lasers.

PubMed

Rosales, Ricardo; Murdoch, S G; Watts, R T; Merghem, K; Martinez, Anthony; Lelarge, Francois; Accard, Alain; Barry, L P; Ramdane, Abderrahim

2012-04-09

Mode locking features of single section quantum dash based lasers are investigated. Particular interest is given to the static spectral phase profile determining the shape of the mode locked pulses. The phase profile dependence on cavity length and injection current is experimentally evaluated, demonstrating the possibility of efficiently using the wide spectral bandwidth exhibited by these quantum dash structures for the generation of high peak power sub-picosecond pulses with low radio frequency linewidths.

INTERNATIONAL CONFERENCE ON SEMICONDUCTOR INJECTION LASERS SELCO-87: Far-field pattern of transverse modes in LOC structures

NASA Astrophysics Data System (ADS)

Petrescu-Prahova, I. B.; Lazanu, S.; Lepşa, M.; Mihailovici, P.

1988-11-01

An investigation was made of the emission from GaAlAs large-optical-cavity (LOC) laser heterostructures with an active layer more than 2 μm thick. The far-field radiation pattern, representing a superposition of the fundamental and several higher-order transverse modes, had a central maximum. The gain, mirror losses, near- and far-field patterns of each propagation mode, as well as mode competition were analyzed on the basis of a simple model. The far-field pattern of single modes was determined by selecting separate spectral intervals from the total emission spectrum of the laser.

Quantum Noise in Laser Diodes

NASA Technical Reports Server (NTRS)

Giacobino, E.; Marin, F.; Bramati, A.; Jost, V.; Poizat, J. Ph.; Roch, J.-F.; Grangier, P.; Zhang, T.-C.

1996-01-01

We have investigated the intensity noise of single mode laser diodes, either free-running or using different types of line narrowing techniques at room temperature. We have measured an intensity squeezing of 1.2 dB with grating-extended cavity lasers and 1.4 dB with injection locked lasers (respectively 1.6 dB and 2.3 dB inferred at the laser output). We have observed that the intensity noise of a free-running nominally single mode laser diode results from a cancellation effect between large anti-correlated fluctuations of the main mode and of weak longitudinal side modes. Reducing the side modes by line narrowing techniques results in intensity squeezing.

Demonstration of enhanced side-mode suppression in metal-filled photonic crystal vertical cavity lasers.

PubMed

Griffin, Benjamin G; Arbabi, Amir; Peun Tan, Meng; Kasten, Ansas M; Choquette, Kent D; Goddard, Lynford L

2013-06-01

Previously reported simulations have suggested that depositing thin layers of metal over the surface of a single-mode, etched air hole photonic crystal (PhC) vertical-cavity surface-emitting laser (VCSEL) could potentially improve the laser's side-mode suppression ratio by introducing additional losses to the higher-order modes. This work demonstrates the concept by presenting the results of a 30 nm thin film of Cr deposited on the surface of an implant-confined PhC VCSEL. Both experimental measurements and simulation results are in agreement showing that the single-mode operation is improved at the same injection current ratio relative to threshold.

High brightness photonic lantern kW-class amplifier

NASA Astrophysics Data System (ADS)

Montoya, Juan; Hwang, Chris; Aleshire, Chris; Reed, Patricia; Martz, Dale; Riley, Mike; Trainor, Michael; Belley, Catherine; Shaw, Scot; Fan, T. Y.; Ripin, Dan

2018-02-01

Pump-limited kW-class operation in a multimode fiber amplifier using adaptive mode control was achieved. A photonic lantern front end was used to inject an arbitrary superposition of modes on the input to a kW-class fiber amplifier to achieve a nearly diffraction-limited output. We report on the adaptive spatial mode control architecture which allows for compensating transverse-mode disturbances at high power. We also describe the advantages of adaptive spatial mode control for optical phased array systems. In particular, we show that the additional degrees of freedom allow for broader steering and improved atmospheric turbulence compensation relative to piston-only optical phased arrays.

Soft Ionization of Saturated Hydrocarbons, Alcohols and Nonpolar Compounds by Negative-Ion Direct Analysis in Real-Time Mass Spectrometry

NASA Astrophysics Data System (ADS)

Cody, Robert B.; Dane, A. John

2013-03-01

Large polarizable n-alkanes (approximately C18 and larger), alcohols, and other nonpolar compounds can be detected as negative ions when sample solutions are injected directly into the sampling orifice of the atmospheric pressure interface of the time-of-flight mass spectrometer with the direct analysis in real time (DART) ion source operating in negative-ion mode. The mass spectra are dominated by peaks corresponding to [M + O2]‾•. No fragmentation is observed, making this a very soft ionization technique for samples that are otherwise difficult to analyze by DART. Detection limits for cholesterol were determined to be in the low nanogram range.

Soft ionization of saturated hydrocarbons, alcohols and nonpolar compounds by negative-ion direct analysis in real-time mass spectrometry.

PubMed

Cody, Robert B; Dane, A John

2013-03-01

Large polarizable n-alkanes (approximately C18 and larger), alcohols, and other nonpolar compounds can be detected as negative ions when sample solutions are injected directly into the sampling orifice of the atmospheric pressure interface of the time-of-flight mass spectrometer with the direct analysis in real time (DART) ion source operating in negative-ion mode. The mass spectra are dominated by peaks corresponding to [M + O2]‾(•). No fragmentation is observed, making this a very soft ionization technique for samples that are otherwise difficult to analyze by DART. Detection limits for cholesterol were determined to be in the low nanogram range.

Dependence of Edge Profiles and Stability on Neutral Beam Power in NSTX

NASA Astrophysics Data System (ADS)

Travis, P.; Canal, G. P.; Osborne, T. H.; Maingi, R.; Sabbagh, S. A.; NSTX-U Team

2016-10-01

Studying the effect of neutral beam injected (NBI) power on edge plasma profiles and magnetohydrodynamic (MHD) stability is central to the understanding of edge-localized modes (ELMs). Higher heating power should quicken the development of pressure and current-driven peeling-ballooning modes. NSTX ELMy H-mode discharges with NBI power of 4, 5 and 6 MW were analyzed with a python-based set of analysis tools that fit plasma profiles, compute kinetic equilibria, and evaluate the MHD stability with the code ELITE. Electron density and temperature from Thomson scattering measurements, and ion density, temperature, and rotation from Charge Exchange Recombination Spectroscopy were inputs to the kinetic equilibrium fits. The power scan provides an opportunity to compare the stability calculations from the ELITE (ideal) and M3D-C1 (resistive) codes. Preliminary analysis shows that edge pressure profiles for the 5 and 6 MW discharges are comparable, suggesting they both reach a stability boundary. The 4 MW case shows lower edge pressure, which is likely limited by edge transport below the edge stability boundary. This work was supported in part by the U.S. Department of Energy, Office of Science, Office of Workforce Development for Teachers and Scientists (WDTS) under the Science Undergraduate Laboratory Internship (SULI) program.

Integrated Physics-based Modeling and Experiments for Improved Prediction of Combustion Dynamics in Low-Emission Systems

NASA Technical Reports Server (NTRS)

Anderson, William E.; Lucht, Robert P.; Mongia, Hukam

2015-01-01

Concurrent simulation and experiment was undertaken to assess the ability of a hybrid RANS-LES model to predict combustion dynamics in a single-element lean direct-inject (LDI) combustor showing self-excited instabilities. High frequency pressure modes produced by Fourier and modal decomposition analysis were compared quantitatively, and trends with equivalence ratio and inlet temperature were compared qualitatively. High frequency OH PLIF and PIV measurements were also taken. Submodels for chemical kinetics and primary and secondary atomization were also tested against the measured behavior. For a point-wise comparison, the amplitudes matched within a factor of two. The dependence on equivalence ratio was matched. Preliminary results from simulation using an 18-reaction kinetics model indicated instability amplitudes closer to measurement. Analysis of the simulations suggested a band of modes around 1400 Hz were due to a vortex bubble breakdown and a band of modes around 6 kHz were due to a precessing vortex core hydrodynamic instability. The primary needs are directly coupled and validated ab initio models of the atomizer free surface flow and the primary atomization processes, and more detailed study of the coupling between the 3D swirling flow and the local thermoacoustics in the diverging venturi section.

The classification of almonds (Prunus dulcis) by country and variety using UHPLC-HRMS-based untargeted metabolomics.

PubMed

Gil Solsona, R; Boix, C; Ibáñez, M; Sancho, J V

2018-03-01

The aim of this study was to use an untargeted UHPLC-HRMS-based metabolomics approach allowing discrimination between almonds based on their origin and variety. Samples were homogenised, extracted with ACN:H 2 O (80:20) containing 0.1% HCOOH and injected in a UHPLC-QTOF instrument in both positive and negative ionisation modes. Principal component analysis (PCA) was performed to ensure the absence of outliers. Partial least squares - discriminant analysis (PLS-DA) was employed to create and validate the models for country (with five different compounds) and variety (with 20 features), showing more than 95% accuracy. Additional samples were injected and the model was evaluated with blind samples, with more than 95% of samples being correctly classified using both models. MS/MS experiments were carried out to tentatively elucidate the highlighted marker compounds (pyranosides, peptides or amino acids, among others). This study has shown the potential of high-resolution mass spectrometry to perform and validate classification models, also providing information concerning the identification of the unexpected biomarkers which showed the highest discriminant power.

Novel Shear-horizontal Surface Acoustic Wave Based Immunosensors Using SiO2Waveguiding Layers And Flow Injection Analysis.

PubMed

Guo, X S; Chen, Y Q; Yang, X L; Wang, L R

2005-01-01

Surface acoustic wave (SAW) devices based on shear-horizontal (SH) waves can be used as mass-sensitive immunosensors. This paper presents a novel SH-SAW sensor to detect anti-immunoglobulin (IgG) molecules by means of the antibody-antigen binding mechanism. The sensor system comprising dual delay lines was fabricated on 36° Y-X LiTaO3substrate. A SiO2layer was used as love mode waveguiding layers, well as insulating and chemically resistant protective layer. Moreover, flow injection analysis (FIA) method was used for continuous detection the protein molecules. The protein A was immobilized on the optional surface of the gold layer, then coupled with IgG to adsorb the antigens to be measured in the protein solution. The operational frequency of the system changed due to the interaction of antibody-antigen binding. The experimental result demonstrates the sensor has stable frequency response to the mass loading effect of the various anti-IgG concentrations with the sensitivity up to 3.3ng/ml/Hz.

Injection locked coupled opto-electronic oscillator for optical frequency comb generation

NASA Astrophysics Data System (ADS)

Williams, Charles; Mandridis, Dimitrios; Davila-Rodriguez, Josue; Delfyett, Peter J.

2011-06-01

A CW injection locked Coupled Opto-Electronic Oscillator (COEO) is presented with a 10.24 GHz spaced optical frequency comb output as well as a low noise RF output. A modified Pound-Drever-Hall scheme is employed to ensure long-term stability of the injection lock, feeding back into the cavity length to compensate for cavity resonance drifts relative to the injection seed frequency. Error signal comparison to an actively mode-locked injection locked laser is presented. High optical signal-to-noise ratio of ~35 dB is demonstrated with >20 comblines of useable bandwidth. The optical linewidth, in agreement with injection locking theory, reduces to that of the injection seed frequency, <5 kHz. Low amplitude and absolute phase noise are presented from the optical output of the laser system. The integrated pulse-to-pulse energy fluctuation was found to be reduced by up to a factor of two due to optical injection. Additional decreases were shown for varying injection powers.

Radiation asymmetries during disruptions on DIII-D caused by massive gas injection

DOE PAGES

Commaux, N.; Baylor, L. R.; Jernigan, T. C.; ...

2014-10-17

One of the major challenges that the ITER tokamak will have to face during its operations are disruptions. During the last few years, it has been proven that the global consequences of a disruption can be mitigated by the injection of large quantities of impurities. But one aspect that has been difficult to study was the possibility of local effects inside the torus during such injection that could damage a portion of the device despite the global heat losses and generated currents remaining below design parameter. 3D MHD simulations show that there is a potential for large toroidal asymmetries ofmore » the radiated power during impurity injection due to the interaction between the particle injection plume and a large n=1 mode. Another aspect of 3D effects is the potential occurrence of Vertical Displacement Events (VDE), which could induce large poloidal heat load asymmetries. This potential deleterious effect of 3D phenomena has been studied on the DIII-D tokamak thanks to the implementation of a multi-location massive gas injection (MGI) system as well as new diagnostic capabilities. This study showed the existence of a correlation between the location of the n=1 mode and the local heat load on the plasma facing components but shows also that this effect is much smaller than anticipated (peaking factor of ~1.1 vs 3-4 according to the simulations). There seems to be no observable heat load on the first wall of DIII-D at the location of the impurity injection port as well as no significant radiation asymmetries whether one or 2 valves are fired. This study enabled the first attempt of mitigation of a VDE using impurity injection at different poloidal locations. The results showed a more favorable heat deposition when the VDE is mitigated early (right at the onset) by impurity injection. As a result, no significant improvement of the heat load mitigation efficiency has been observed for late particle injection whether the injection is done “in the way” of the VDE (upward VDE mitigated by injection from the upper part of the vessel vs the lower part) or not.« less

Monitoring the Restart of a High-Rate Wastewater Disposal Well in the Val d'Agri Oilfield (Italy)

NASA Astrophysics Data System (ADS)

De Gori, P.; Improta, L.; Moretti, M.; Colasanti, G.; Criscuoli, F.

2015-12-01

The Val d'Agri Quaternary basin in the Southern Apennine range of Italy hosts the largest inland oil field in Europe. Wastewater coming from the oil exploitation is re-injected by a high-rate disposal well into strongly fractured limestones of the hydrocarbon carbonate reservoir. Disposal activity has induced micro-seismicity since the beginning of injection in June 2006. Around 220 small magnitude events (ML < 2.3) were recorded between 2006 and 2013 by the trigger-mode monitoring local network managed by the oil company and by the National Seismic Network of Istituto Nazionale di Geofisica e Vulcanologia. The induced micro-seismicity illuminated a pre-existing high-angle fault located 1 km below the well. Since June 2006, wastewater has been re-injected with only short interruptions due acid stimulations. In January 2015 disposal activity was halted due to technical operations in the oil refinery and wastewater injection restarted after two weeks. We installed 5 short-period stations within 10 km of the disposal well to carefully monitor the re-start phase and the subsequent 3 months of disposal activity. This temporary network was complemented by stations of the National Seismic Network giving this final configuration:9 stations within 10 km of the well with the closest station 2 km apart, 13 stations within 20 km. Here we report on the preliminary analysis of the local earthquake recorded during the survey focusing on the events occurred in the injection area. The seismicity rate is compared with injection data.In spite of the dense network, we found that the rate of induced seismicity (both the number and energy of events) is very low when compared to the seismicity recorded during the first 5 years of injection activity carried out with comparable rate and pressure.

Plasma shut-down with fast impurity puff on ASDEX Upgrade

NASA Astrophysics Data System (ADS)

Pautasso, G.; Fuchs, C. J.; Gruber, O.; Maggi, C. F.; Maraschek, M.; Pütterich, T.; Rohde, V.; Wittmann, C.; Wolfrum, E.; Cierpka, P.; Beck, M.; ASDEX Upgrade Team

2007-08-01

The massive injection of impurity gas into a plasma has been proved to reduce forces and localized thermal loads caused by disruptions in tokamaks. This mitigation system is routinely used on ASDEX Upgrade to shut down plasmas with a locked mode. The plasma response to impurity injection and the mechanism of reduction of the mechanical forces is discussed in the paper.

Alternative delivery of male accessory gland products

PubMed Central

2014-01-01

To increase fertilization success, males transfer accessory gland products (Acps). Several species have evolved unconventional Acps transfer modes, meaning that Acps are transferred separately from the sperm. By surveying the sperm-free Acps transfer cases, we show that these animals have evolved a common strategy to deliver Acps: they all inject Acps directly through the partner’s body wall into the hemolymph. Our review of this mode of Acps transfer reveals another striking similarity: they all transfer sperm in packages or via the skin, which may leave little room for Acps transfer via the conventional route in seminal fluid. We synthesise the knowledge about the function, and the effects in the recipients, of the Acps found in the widely diverse taxa (including earthworms, sea slugs, terrestrial snails, scorpions and salamanders) that inject these substances. Despite the clearly independent evolution of the injection devices, these animals have evolved a common alternative strategy to get their partners to accept and/or use their sperm. Most importantly, the evolution of the injection devices for the delivery of Acps highlights how the latter are pivotal for male reproductive success and, hence, strongly influence sexual selection. PMID:24708537

Direct observation of generation and propagation of magnetosonic waves following substorm injection

NASA Astrophysics Data System (ADS)

Su, Z.; Wang, G.; Liu, N.; Zheng, H.; Wang, Y.; Wang, S.

2017-12-01

Magnetosonic whistler mode waves play an important role in the radiation belt electron dynamics. Previous theory has suggested that these waves are excited by the ring distributions of hot protons and can propagate radially and azimuthally over a broad spatial range. However, because of the challenging requirements on satellite locations and data-processing techniques, this theory was difficult to validate directly. Here we present some experimental tests of the theory on the basis of Van Allen Probes observations of magnetosonic waves following substorm injections. At higher L-shells with significant substorm injections, the discrete magnetosonic emission lines started approximately at the proton gyrofrequency harmonics, qualitatively consistent with the prediction of linear proton Bernstein mode instability. In the frequency-time spectrograms, these emission lines exhibited a clear rising tone characteristic with a long duration of 15-25 mins, implying the additional contribution of other undiscovered mechanisms. Nearly at the same time, the magnetosonic waves arose at lower L-shells without substorm injections. The wave signals at two different locations, separated by ΔL up to 2.0 and by ΔMLT up to 4.2, displayed the consistent frequency-time structures, strongly supporting the hypothesis about the radial and azimuthal propagation of magnetosonic waves.

NIMROD simulations and physics assessment of possible designs for a next generation Steady Inductive Helicity Injection HIT device

NASA Astrophysics Data System (ADS)

Penna, James; Morgan, Kyle; Grubb, Isaac; Jarboe, Thomas

2017-10-01

The Helicity Injected Torus - Steady Inductive 3 (HIT-SI3) experiment forms and maintains spheromaks via Steady Inductive Helicity Injection (SIHI) using discrete injectors that inject magnetic helicity via a non-axisymmetric perturbation and drive toroidally symmetric current. Newer designs for larger SIHI-driven spheromaks incorporate a set of injectors connected to a single external manifold to allow more freedom for the toroidal structure of the applied perturbation. Simulations have been carried out using the NIMROD code to assess the effectiveness of various imposed mode structures and injector schema in driving current via Imposed Dynamo Current Drive (IDCD). The results are presented here for varying flux conserver shapes on a device approximately 1.5 times larger than the current HIT-SI3 experiment. The imposed mode structures and spectra of simulated spheromaks are analyzed in order to examine magnetic structure and stability and determine an optimal regime for IDCD sustainment in a large device. The development of scaling laws for manifold operation is also presented, and simulation results are analyzed and assessed as part of the development path for the large scale device.

Mode-locking of a terahertz laser by direct phase synchronization.

PubMed

Maysonnave, J; Maussang, K; Freeman, J R; Jukam, N; Madéo, J; Cavalié, P; Rungsawang, R; Khanna, S P; Linfield, E H; Davies, A G; Beere, H E; Ritchie, D A; Dhillon, S S; Tignon, J

2012-09-10

A novel scheme to achieve mode-locking of a multimode laser is demonstrated. Traditional methods to produce ultrashort laser pulses are based on modulating the cavity gain or losses at the cavity roundtrip frequency, favoring the pulsed emission. Here, we rather directly act on the phases of the modes, resulting in constructive interference for the appropriated phase relationship. This was performed on a terahertz quantum cascade laser by multimode injection seeding with an external terahertz pulse, resulting in phase mode-locked terahertz laser pulses of 9 ps duration, characterized unambiguously in the time domain.

Linear Temporal Stability Analysis of a Low-Density Round Gas Jet Injected into a High-Density Gas

NASA Technical Reports Server (NTRS)

Lawson, Anthony L.; Parthasarathy, Ramkumar N.

2002-01-01

It has been observed in previous experimental studies that round helium jets injected into air display a repetitive structure for a long distance, somewhat similar to the buoyancy-induced flickering observed in diffusion flames. In order to investigate the influence of gravity on the near-injector development of the flow, a linear temporal stability analysis of a round helium jet injected into air was performed. The flow was assumed to be isothermal and locally parallel; viscous and diffusive effects were ignored. The variables were represented as the sum of the mean value and a normal-mode small disturbance. An ordinary differential equation governing the amplitude of the pressure disturbance was derived. The velocity and density profiles in the shear layer, and the Froude number (signifying the effects of gravity) were the three important parameters in this equation. Together with the boundary conditions, an eigenvalue problem was formulated. Assuming that the velocity and density profiles in the shear layer to be represented by hyperbolic tangent functions, the eigenvalue problem was solved for various values of Froude number. The temporal growth rates and the phase velocity of the disturbances were obtained. The temporal growth rates of the disturbances increased as the Froude number was reduced (i.e. gravitational effects increased), indicating the destabilizing role played by gravity.

Automated rejection of parasitic frequency sidebands in heterodyne-detection LIDAR applications

NASA Technical Reports Server (NTRS)

Esproles, Carlos; Tratt, David M.; Menzies, Robert T.

1989-01-01

A technique is described for the detection of the sporadic onset of multiaxial mode behavior of a normally single-mode TEA CO2 laser. The technique is implemented using primarily commercial circuit modules; it incorporates a peak detector that displays the RF detector output on a digital voltmeter, and a LED bar graph. The technique was successfully demonstrated with an existing coherent atmospheric LIDAR facility utilizing an injection-seeded single-mode TEA CO2 laser. The block schematic diagram is included.

Generation of noninductive current by electron-Bernstein waves on the COMPASS-D Tokamak.

PubMed

Shevchenko, V; Baranov, Y; O'Brien, M; Saveliev, A

2002-12-23

Electron-Bernstein waves (EBW) were excited in the plasma by mode converted extraordinary (X) waves launched from the high field side of the COMPASS-D tokamak at different toroidal angles. It has been found experimentally that X-mode injection perpendicular to the magnetic field provides maximum heating efficiency. Noninductive currents of up to 100 kA were found to be driven by the EBW mode with countercurrent drive. These results are consistent with ray tracing and quasilinear Fokker-Planck simulations.

First results of geodetic deformation monitoring after commencement of CO2 injection at the Aquistore underground CO2 storage site

NASA Astrophysics Data System (ADS)

Craymer, M.; White, D.; Piraszewski, M.; Zhao, Y.; Henton, J.; Silliker, J.; Samsonov, S.

2015-12-01

Aquistore is a demonstration project for the underground storage of CO2 at a depth of ~3350 m near Estevan, Saskatchewan, Canada. An objective of the project is to design, adapt, and test non-seismic monitoring methods that have not been systematically utilized to date for monitoring CO2 storage projects, and to integrate the data from these various monitoring tools to obtain quantitative estimates of the change in subsurface fluid distributions, pressure changes and associated surface deformation. Monitoring methods being applied include satellite-, surface- and wellbore-based monitoring systems and comprise natural- and controlled-source electromagnetic methods, gravity monitoring, continuous GPS, synthetic aperture radar interferometry (InSAR), tiltmeter array analysis, and chemical tracer studies. Here we focus on the GPS, InSAR and gravity monitoring. Five monitoring sites were installed in 2012 and another six in 2013, each including GPS and InSAR corner reflector monuments (some collocated on the same monument). The continuous GPS data from these stations have been processed on a daily basis in both baseline processing mode using the Bernese GPS Software and precise point positioning mode using CSRS-PPP. Gravity measurements at each site have also been performed in fall 2013, spring 2014 and fall 2015, and at two sites in fall 2014. InSAR measurements of deformation have been obtained for a 5 m footprint at each site as well as at the corner reflector point sources. Here we present the first results of this geodetic deformation monitoring after commencement of CO2 injection on April 14, 2015. The time series of these sites are examined, compared and analyzed with respect to monument stability, seasonal signals, longer term trends, and any changes in motion and mass since CO2 injection.

RF Priming Experiments and Simulations of Magnetic Priming in Relativistic Magnetrons

NASA Astrophysics Data System (ADS)

White, W. M.; Gilgenbach, R. M.; Jones, M. C.; Neculaes, V. B.; Lau, Y. Y.; Jordan, N.; Pengvanich, P.; Edgar, R.; Hoff, B.; Spencer, T. A.; Price, D.

2004-11-01

We investigate 2 priming techniques in relativistic magnetrons for rapid startup and mode-locking: RF priming experiments with 0.1-1 MW from a 2nd magnetron; Magnetic-priming simulations by azimuthally-varying-axial magnetic field. Experiments utilize MELBA-C with a Titan 6-vane magnetron: V = -300kV, I = 1-10kA, e-beam T = 0.5 μs, microwave power = 100-500 MW, f= 1-1.3 GHz, base vacuum= 8.5 x 10-10 Torr. The AFRL RF priming magnetron is at 0.1-2 MW, 3 μsec, 1.27-1.32 GHz. About 0.2-0.3 MW is injected into 1 of 3 open coupling slots in the relativistic magnetron. Analysis of the relativistic magnetron's microwave output shows a clear effect of RF priming. Simulations of magnetic priming in the pi-mode are run in MAGIC code by imposing N/2 azimuthal-variations in the axial magnetic field of an N-vane magnetron. Faster startup and mode-locking are simulated by rapid-electron spoke formation and excitation of RF fields.

In-fiber refractive index sensor based on single eccentric hole-assisted dual-core fiber.

PubMed

Yang, Jing; Guan, Chunying; Tian, Peixuan; Yuan, Tingting; Zhu, Zheng; Li, Ping; Shi, Jinhui; Yang, Jun; Yuan, Libo

2017-11-01

We propose a novel and simple in-fiber refractive index sensor based on resonant coupling, constructed by a short section of single eccentric hole-assisted dual-core fiber (SEHADCF) spliced between two single-mode fibers. The coupling characteristics of the SEHADCF are calculated numerically. The strong resonant coupling occurs when the fundamental mode of the center core phase-matches to that of the suspended core in the air hole. The effective refractive index of the fundamental mode of the suspended core can be obviously changed by injecting solution into the air hole. The responses of the proposed devices to the refractive index and temperature are experimentally measured. The refractive index sensitivity is 627.5 nm/refractive index unit in the refractive index range of 1.335-1.385. The sensor without solution filling is insensitive to temperature in the range of 30-90°C. The proposed refractive index sensor has outstanding advantages, such as simple fabrication, good mechanical strength, and excellent microfluidic channel, and will be of importance in biological detection, chemical analysis, and environment monitoring.

Abundance and modes of occurrence of mercury in some low-sulfur coals from China

USGS Publications Warehouse

Zheng, Lingyun; Liu, Gaisheng; Chou, C.-L.

2008-01-01

Mercury (Hg) is one of the hazardous trace elements in coal. Mercury in coal is almost totally emitted into the atmosphere during coal combustion. Especially for utilities burning low-sulfur coals that do not require scrubbers, Hg reduction will be neglected. Hg abundances of 52 low-sulfur coal samples from different coalfields in six provinces of China were determined by a flow injection mercury system (FIMS). The results show that Hg abundances in selected low-sulfur coals range from 0.03??ppm to 0.79??ppm, with an arithmetic mean of 0.24??ppm, which is higher than that of average Chinese coals (0.19??ppm). Correlation analysis and sequential extraction procedures are performed to study possible modes of occurrence of Hg in low-sulfur coals. Modes of occurrence of Hg are variable in low-sulfur coals, and the sulfide-bound and organic-bound Hg may be the dominant forms. In addition, the silicate-bound Hg may be the main form in some of these coals because of magmatic intrusion. ?? 2007 Elsevier B.V. All rights reserved.

Top-up operation at Pohang Light Source-II

NASA Astrophysics Data System (ADS)

Hwang, I.; Huang, J. Y.; Kim, M.; Lee, B.-J.; Kim, C.; Choi, J.-Y.; Kim, M.-H.; Lee, H. S.; Moon, D.; Lee, E. H.; Kim, D.-E.; Nam, S. H.; Shin, S.; Cho, Moohyun

2014-05-01

After three years of upgrading work, PLS-II (S. Shin, Commissioning of the PLS-II, JINST, January 2013) is now successfully operating. The top-up operation of the 3 GeV linear accelerator had to be delayed because of some challenges encountered, and PLS-II was run in decay mode at the beginning in March 2012. The main difficulties encountered in the top-up operation of PLS-II are different levels between the linear accelerator and the storage ring, the 14 narrow gap in-vacuum undulators in operation, and the full energy injection by 3 GeV linear accelerator. Large vertical emittance and energy jitter of the linac were the major obstacles that called for careful control of injected beam to reduce beam loss in the storage ring during injection. The following measures were taken to resolve these problems: (1) The high resolution Libera BPM (see http://www.i-tech.si) was implemented to measure the beam trajectory and energy. (2) Three slit systems were installed to filter the beam edge. (3) De-Qing circuit was applied to the modulator system to improve the energy stability of injected beam. As a result, the radiation by beam loss during injection is reduced drastically, and the top-up mode has been successfully operating since 19th March 2013. In this paper, we describe the experimental results of the PLS-II top-up operation and the improvement plan.

The effect of pre-existing islands on disruption mitigation in MHD simulations of DIII-D

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

Izzo, V. A.

Locked-modes are the most likely cause of disruptions in ITER, so large islands are expected to be common when the ITER disruption mitigation system is deployed. MHD modeling of disruption mitigation by massive gas injection is carried out for DIII-D plasmas with stationary, pre-existing islands. Results show that the magnetic topology at the q=2 surface can affect the parallel spreading of injected impurities, and that, in particular, the break-up of large 2/1 islands into smaller 4/2 islands chains can favorably affect mitigation metrics. The direct imposition of a 4/2 mode is found to have similar results to the case inmore » which the 4/2 harmonic grows spontaneously.« less

The effect of pre-existing islands on disruption mitigation in MHD simulations of DIII-D

DOE PAGES

Izzo, V. A.

2017-02-27

Locked-modes are the most likely cause of disruptions in ITER, so large islands are expected to be common when the ITER disruption mitigation system is deployed. MHD modeling of disruption mitigation by massive gas injection is carried out for DIII-D plasmas with stationary, pre-existing islands. Results show that the magnetic topology at the q=2 surface can affect the parallel spreading of injected impurities, and that, in particular, the break-up of large 2/1 islands into smaller 4/2 islands chains can favorably affect mitigation metrics. The direct imposition of a 4/2 mode is found to have similar results to the case inmore » which the 4/2 harmonic grows spontaneously.« less

FIBRE AND INTEGRATED OPTICS. OPTICAL PROCESSING OF INFORMATION: Feasibility of using waveguide holograms in systems for the transfer of amplitude—phase information along fibre communication lines

NASA Astrophysics Data System (ADS)

Dianov, Evgenii M.; Zubov, Vladimir A.; Putilin, A. N.

1995-02-01

An analysis is made of a variant of a system for spatial—temporal transformation of spatially one-dimensional information for its transfer along a single-mode fibre waveguide. Information is coupled into a fibre by a waveguide hologram. This hologram forms a light-beam structure which matches the fibre-guided mode. A report is given of the use of ion-exchange planar glass waveguides as waveguide holograms. An amorphous chalcogenide semiconductor film or a photoresist was deposited by evaporation on such a planar waveguide. Reconstruction of the waveguide hologram made it possible to achieve a high read rate, up to 1011 pixels per second, when a short radiation pulse was used. Multisectioned injection semiconductor lasers, operating under Q-switching conditions, were used as the radiation sources.

Distributed Adaptive Fuzzy Control for Nonlinear Multiagent Systems Via Sliding Mode Observers.

PubMed

Shen, Qikun; Shi, Peng; Shi, Yan

2016-12-01

In this paper, the problem of distributed adaptive fuzzy control is investigated for high-order uncertain nonlinear multiagent systems on directed graph with a fixed topology. It is assumed that only the outputs of each follower and its neighbors are available in the design of its distributed controllers. Equivalent output injection sliding mode observers are proposed for each follower to estimate the states of itself and its neighbors, and an observer-based distributed adaptive controller is designed for each follower to guarantee that it asymptotically synchronizes to a leader with tracking errors being semi-globally uniform ultimate bounded, in which fuzzy logic systems are utilized to approximate unknown functions. Based on algebraic graph theory and Lyapunov function approach, using Filippov-framework, the closed-loop system stability analysis is conducted. Finally, numerical simulations are provided to illustrate the effectiveness and potential of the developed design techniques.

Steady-state generation of hydrogen peroxide: kinetics and stability of alcohol oxidase immobilized on nanoporous alumina.

PubMed

Kjellander, Marcus; Götz, Kathrin; Liljeruhm, Josefine; Boman, Mats; Johansson, Gunnar

2013-04-01

Alcohol oxidase from Pichia pastoris was immobilized on nanoporous aluminium oxide membranes by silanization and activation by carbonyldiimidazole to create a flow-through enzyme reactor. Kinetic analysis of the hydrogen peroxide generation was carried out for a number of alcohols using a subsequent reaction with horseradish peroxidase and ABTS. The activity data for the immobilized enzyme showed a general similarity with literature data in solution, and the reactor could generate 80 mmol H2O2/h per litre reactor volume. Horseradish peroxidase was immobilized by the same technique to construct bienzymatic modular reactors. These were used in both single pass mode and circulating mode. Pulsed injections of methanol resulted in a linear relation between response and concentration, allowing quantitative concentration measurement. The immobilized alcohol oxidase retained 58 % of initial activity after 3 weeks of storage and repeated use.

Laser dynamics: The system dynamics and network theory of optoelectronic integrated circuit design

NASA Astrophysics Data System (ADS)

Tarng, Tom Shinming-T. K.

Laser dynamics is the system dynamics, communication and network theory for the design of opto-electronic integrated circuit (OEIC). Combining the optical network theory and optical communication theory, the system analysis and design for the OEIC fundamental building blocks is considered. These building blocks include the direct current modulation, inject light modulation, wideband filter, super-gain optical amplifier, E/O and O/O optical bistability and current-controlled optical oscillator. Based on the rate equations, the phase diagram and phase portrait analysis is applied to the theoretical studies and numerical simulation. The OEIC system design methodologies are developed for the OEIC design. Stimulating-field-dependent rate equations are used to model the line-width narrowing/broadening mechanism for the CW mode and frequency chirp of semiconductor lasers. The momentary spectra are carrier-density-dependent. Furthermore, the phase portrait analysis and the nonlinear refractive index is used to simulate the single mode frequency chirp. The average spectra of chaos, period doubling, period pulsing, multi-loops and analog modulation are generated and analyzed. The bifurcation-chirp design chart with modulation depth and modulation frequency as parameters is provided for design purpose.

Liquid Microjunction Surface Sampling Probe Fluid Dynamics: Computational and Experimental Analysis of Coaxial Intercapillary Positioning Effects on Sample Manipulation

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

ElNaggar, Mariam S; Barbier, Charlotte N; Van Berkel, Gary J

A coaxial geometry liquid microjunction surface sampling probe (LMJ-SSP) enables direct extraction of analytes from surfaces for subsequent analysis by techniques like mass spectrometry. Solution dynamics at the probe-to-sample surface interface in the LMJ-SSP has been suspected to influence sampling efficiency and dispersion but has not been rigorously investigated. The effect on flow dynamics and analyte transport to the mass spectrometer caused by coaxial retraction of the inner and outer capillaries from each other and the surface during sampling with a LMJ-SSP was investigated using computational fluid dynamics and experimentation. A transparent LMJ-SSP was constructed to provide the means formore » visual observation of the dynamics of the surface sampling process. Visual observation, computational fluid dynamics (CFD) analysis, and experimental results revealed that inner capillary axial retraction from the flush position relative to the outer capillary transitioned the probe from a continuous sampling and injection mode through an intermediate regime to sample plug formationmode caused by eddy currents at the sampling end of the probe. The potential for analytical implementation of these newly discovered probe operational modes is discussed.« less

Destabilization of low-n peeling modes by trapped energetic particles

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

Hao, G. Z.; Wang, A. K.; Mou, Z. Z.

2013-06-15

The kinetic effect of trapped energetic particles (EPs), arising from perpendicular neutral beam injection, on the stable low-n peeling modes in tokamak plasmas is investigated, through numerical solution of the mode's dispersion relation derived from an energy principle. A resistive-wall peeling mode with m/n=6/1, with m and n being the poloidal and toroidal mode numbers, respectively, is destabilized by trapped EPs as the EPs' pressure exceeds a critical value β{sub c}{sup *}, which is sensitive to the pitch angle of trapped EPs. The dependence of β{sub c}{sup *} on the particle pitch angle is eventually determined by the bounce averagemore » of the mode eigenfunction. Peeling modes with higher m and n numbers can also be destabilized by trapped EPs. Depending on the wall distance, either a resistive-wall peeling mode or an ideal-kink peeling mode can be destabilized by EPs.« less

Radiation asymmetries during disruptions on DIII-D caused by massive gas injectiona)

NASA Astrophysics Data System (ADS)

Commaux, N.; Baylor, L. R.; Jernigan, T. C.; Hollmann, E. M.; Humphreys, D. A.; Wesley, J. C.; Izzo, V. A.; Eidietis, N. W.; Lasnier, C. J.; Moyer, R. A.; Parks, P. B.; Foust, C. R.; Combs, S.; Meitner, S. J.

2014-10-01

One of the major challenges that the ITER tokamak will have to face during its operations are disruptions. During the last few years, it has been proven that the global consequences of a disruption can be mitigated by the injection of large quantities of impurities. But one aspect that has been difficult to study was the possibility of local effects inside the torus during such injection that could damage a portion of the device despite the global heat losses and generated currents remaining below design parameter. 3D MHD simulations show that there is a potential for large toroidal asymmetries of the radiated power during impurity injection due to the interaction between the particle injection plume and a large n = 1 mode. Another aspect of 3D effects is the potential occurrence of Vertical Displacement Events (VDE), which could induce large poloidal heat load asymmetries. This potential deleterious effect of 3D phenomena has been studied on the DIII-D tokamak, thanks to the implementation of a multi-location massive gas injection (MGI) system as well as new diagnostic capabilities. This study showed the existence of a correlation between the location of the n = 1 mode and the local heat load on the plasma facing components but shows also that this effect is much smaller than anticipated (peaking factor of ˜1.1 vs 3-4 according to the simulations). There seems to be no observable heat load on the first wall of DIII-D at the location of the impurity injection port as well as no significant radiation asymmetries whether one or 2 valves are fired. This study enabled the first attempt of mitigation of a VDE using impurity injection at different poloidal locations. The results showed a more favorable heat deposition when the VDE is mitigated early (right at the onset) by impurity injection. No significant improvement of the heat load mitigation efficiency has been observed for late particle injection whether the injection is done "in the way" of the VDE (upward VDE mitigated by injection from the upper part of the vessel vs the lower part) or not.

Excess spontaneous emission in non-Hermitian optical systems. I. Laser amplifiers

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

Siegman, A.E.

1989-02-01

Petermann first predicted in 1979 the existence of an excess-spontaneous-emission factor in gain-guided semiconductor lasers. We show that an excess spontaneous emission of this type, and also a correlation between the spontaneous emission into different cavity modes, will in fact be present in all open-sided laser resonators or optical lens guides. These properties arise from the non-self-adjoint or non-power-orthogonal nature of the optical resonator modes. The spontaneous-emission rate is only slightly enhanced in stable-resonator or index-guided structures, but can become very much larger than normal in gain-guided or geometrically unstable structures. Optical resonators or lens guides that have an excessmore » noise emission necessarily also exhibit an ''excess initial-mode excitation factor'' for externally injected signals. As a result, the excess spontaneous emission can be balanced out and the usual quantum-noise limit recovered in laser amplifiers and in injection-seeded laser oscillators, but not in free-running laser oscillators.« less

Mode stabilization in quantum cascade lasers via an intra-cavity cascaded nonlinearity.

PubMed

St-Jean, M Renaudat; Amanti, M I; Bismuto, A; Beck, M; Faist, J; Sirtori, C

2017-02-06

We present self-stabilization of the inter-mode separation of a quantum cascade laser (QCL) emitting at 9 μm via cascaded second order nonlinearity. This effect has been observed in lasers that have the optical cavity embedded into a microwave strip-line. The intermodal beat note spectra narrow with increasing laser output power, up to less than 100 kHz. A flat frequency response to direct modulation up to 14 GHz is reported for these microstrip QCLs. The laser inter-mode spacing can be locked to an external RF signal and tuned by more than 1 MHz from the free-running spacing. A parallel study on the same laser material in a non-microstrip line waveguide shows superior performances of the microstrip QCL in terms of the intermodal spectral locking and stability. Finally by analyzing our results with the theory of the injection locking of coupled oscillators, we deduce that the microwave power injected in the microstrip QCL is 2 orders of magnitude higher than in the reference laser.

Suppression law of quantum states in a 3D photonic fast Fourier transform chip

PubMed Central

Crespi, Andrea; Osellame, Roberto; Ramponi, Roberta; Bentivegna, Marco; Flamini, Fulvio; Spagnolo, Nicolò; Viggianiello, Niko; Innocenti, Luca; Mataloni, Paolo; Sciarrino, Fabio

2016-01-01

The identification of phenomena able to pinpoint quantum interference is attracting large interest. Indeed, a generalization of the Hong–Ou–Mandel effect valid for any number of photons and optical modes would represent an important leap ahead both from a fundamental perspective and for practical applications, such as certification of photonic quantum devices, whose computational speedup is expected to depend critically on multi-particle interference. Quantum distinctive features have been predicted for many particles injected into multimode interferometers implementing the Fourier transform over the optical modes. Here we develop a scalable approach for the implementation of the fast Fourier transform algorithm using three-dimensional photonic integrated interferometers, fabricated via femtosecond laser writing technique. We observe the suppression law for a large number of output states with four- and eight-mode optical circuits: the experimental results demonstrate genuine quantum interference between the injected photons, thus offering a powerful tool for diagnostic of photonic platforms. PMID:26843135

MHD and resonant instabilities in JT-60SA during current ramp-up with off-axis N-NB injection

NASA Astrophysics Data System (ADS)

Bierwage, A.; Toma, M.; Shinohara, K.

2017-12-01

The excitation of magnetohydrodynamic (MHD) and resonant instabilities and their effect on the plasma profiles during the current ramp-up phase of a beam-driven JT-60SA tokamak plasma is studied using the MHD-PIC hybrid code MEGA. In the simple scenario considered, the plasma is only driven by one negative-ion-based neutral beam, depositing 500 keV deuterons at 5 MW power off-axis at about mid-radius. The beam injection starts half-way in the ramp-up phase. Within 1 s, the beam-driven plasma current and fast ion pressure produce a configuration that is strongly unstable to rapidly growing MHD and resonant modes. Using MEGA, modes with low toroidal mode numbers in the range n = 1-4 are examined in detail and shown to cause substantial changes in the plasma profiles. The necessity to develop reduced models and incorporate the effects of such instabilities in integrated codes used to simulate the evolution of entire plasma discharges is discussed.

Failure strengths of denture teeth fabricated on injection molded or compression molded denture base resins.

PubMed

Robison, Nathan E; Tantbirojn, Daranee; Versluis, Antheunis; Cagna, David R

2016-08-01

Denture tooth fracture or debonding remains a common problem in removable prosthodontics. The purpose of this in vitro study was to explore factors determining failure strengths for combinations of different denture tooth designs (shape, materials) and injection or compression molded denture base resins. Three central incisor denture tooth designs were tested: nanohybrid composite (NHC; Ivoclar Phonares II), interpenetrating network (IPN; Dentsply Portrait), and microfiller reinforced polyacrylic (MRP; VITA Physiodens). Denture teeth of each type were processed on an injection molded resin (IvoBase HI; Ivoclar Vivadent AG) or a compression molded resin (Lucitone 199; Dentsply Intl) (n=11 or 12). The denture teeth were loaded at 45 degrees on the incisal edge. The failure load was recorded and analyzed with 2-way ANOVA (α=.05), and the fracture mode was categorized from observed fracture surfaces as cohesive, adhesive, or mixed failure. The following failure loads (mean ±SD) were recorded: NHC/injection molded 280 ±52 N; IPN/injection molded 331 ±41 N; MRP/injection molded 247 ±23 N; NHC/compression molded 204 ±31 N; IPN/compression molded 184 ±17 N; MRP/compression molded 201 ±16 N. Injection molded resin yielded significantly higher failure strength for all denture teeth (P<.001), among which IPN had the highest strength. Failure was predominantly cohesive in the teeth, with the exception of mixed mode for the IPN/compression group. When good bonding was achieved, the strength of the structure (denture tooth/base resin combination) was determined by the strength of the denture teeth, which may be affected by the processing technique. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Carrier-envelope phase-controlled quantum interference of injected photocurrents in semiconductors.

PubMed

Fortier, T M; Roos, P A; Jones, D J; Cundiff, S T; Bhat, R D R; Sipe, J E

2004-04-09

We demonstrate quantum interference control of injected photocurrents in a semiconductor using the phase stabilized pulse train from a mode-locked Ti:sapphire laser. Measurement of the comb offset frequency via this technique results in a signal-to-noise ratio of 40 dB (10 Hz resolution bandwidth), enabling solid-state detection of carrier-envelope phase shifts of a Ti:sapphire oscillator.

Whispering Gallery Mode Resonators for Rapid Label-Free Biosensing in Small Volume Droplets

PubMed Central

Wildgen, Sarah M.; Dunn, Robert C.

2015-01-01

Rapid biosensing requires fast mass transport of the analyte to the surface of the sensing element. To optimize analysis times, both mass transport in solution and the geometry and size of the sensing element need to be considered. Small dielectric spheres, tens of microns in diameter, can act as label-free biosensors using whispering gallery mode (WGM) resonances. WGM resonances are sensitive to the effective refractive index, which changes upon analyte binding to recognition sites on functionalized resonators. The spherical geometry and tens of microns diameter of these resonators provides an efficient target for sensing while their compact size enables detection in limited volumes. Here, we explore conditions leading to rapid analyte detection using WGM resonators as label-free sensors in 10 μL sample droplets. Droplet evaporation leads to potentially useful convective mixing, but also limits the time over which analysis can be completed. We show that active droplet mixing combined with initial binding rate measurements is required for accurate nanomolar protein quantification within the first minute following injection. PMID:25806835

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

Goumiri, I. R.; Rowley, C. W.; Sabbagh, S. A.

In this study, a model-based feedback system is presented enabling the simultaneous control of the stored energy through β n and the toroidal rotation profile of the plasma in National Spherical Torus eXperiment Upgrade device. Actuation is obtained using the momentum from six injected neutral beams and the neoclassical toroidal viscosity generated by applying three-dimensional magnetic fields. Based on a model of the momentum diffusion and torque balance, a feedback controller is designed and tested in closed-loop simulations using TRANSP, a time dependent transport analysis code, in predictive mode. Promising results for the ongoing experimental implementation of controllers are obtained.

Modeling of Karachaganak field development

NASA Astrophysics Data System (ADS)

Sadvakasov, A. A.; Shamsutdinova, G. F.; Almukhametova, E. M.; Gabdrakhmanov, N. Kh

2018-05-01

Management of a geological deposit includes the study and analysis of oil recovery, identification of factors influencing production performance and oil-bearing rock flooding, reserve recovery and other indicators characterizing field development in general. Regulation of oil deposits exploitation is a mere control over the fluid flow within a reservoir, which is ensured through the designed system of development via continuous improvement of production and injection wells placement, optimum performance modes, service conditions of downhole and surface oil-field equipment taking into account various changes and physical-geological properties of a field when using modern equipment to obtain the best performance indicators.

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

Saxberg, Brendan; Plotkin-Swing, Benjamin; Gupta, Subhadeep

We report on a device to electronically stabilize the optical injection lock of a semiconductor diode laser. Our technique uses as discriminator the peak height of the laser’s transmission signal on a scanning Fabry-Perot cavity and feeds back to the diode current, thereby maintaining maximum optical power in the injected mode. A two-component feedback algorithm provides constant optimization of the injection lock, keeping it robust to slow thermal drifts and allowing fast recovery from sudden failures such as temporary occlusion of the injection beam. We demonstrate the successful performance of our stabilization method in a diode laser setup at 399more » nm used for laser cooling of Yb atoms. The device eases the requirements on passive stabilization and can benefit any diode laser injection lock application, particularly those where several such locks are employed.« less

Use of high-performance liquid chromatography with diode array detection coupled to electrospray-Qq-time-of-flight mass spectrometry for the direct characterization of the phenolic fraction in organic commercial juices.

PubMed

Rodríguez-Medina, I C; Segura-Carretero, A; Fernández-Gutiérrez, A

2009-06-05

We have developed a direct method for the qualitative analysis of polyphenols in commercial organic fruit juices. The juices were diluted with water (50/50), filtered and directly injected. The analysis of phenolic compounds was carried out by reversed-phase high-performance liquid chromatography (RP-HPLC) coupled to photodiode array detection (DAD) and electrospray ionisation-Qq-time-of-flight mass spectrometry (ESI-Qq-TOF-MS). A unique gradient program has been optimized for the separation of several phenolic classes and the analysis time was only 5 min. The fruit juice samples were successfully analysed in positive and negative ionisation modes. In positive mode the anthocyanins were identified whereas the vast majority of polyphenols were identified using the negative ionisation mode. The sensitivity, together with mass accuracy and true isotopic pattern of the Qq-TOF-MS, allowed the identification of the phenolic compounds. Moreover, the advantage of the proposed method is the combined search of MS and MS/MS spectra, which improves the identification of compounds considerably, reducing ambiguities and false positive hits. Therefore the total fragmentation of the compound ion leading to the aglycone ion or other fragments was corroborated by MS-MS. The method was successfully employed to characterize diverse phenolic families in commercially available organic juices from four different fruits and consequently could be used in the future for the quantification purposes to compare different content of polyphenols in juices.

Toroidal rotation and ion heating during neutral beam injection in PBX-M

NASA Astrophysics Data System (ADS)

Asakura, N.; Fonck, R. J.; Jaehnig, K. P.; Kaye, S. M.; LeBlanc, B.; Okabayashi, M.

1993-08-01

Determination of the profiles of the ion temperature and the plasma toroidal rotation has been accomplished by charge exchange recombination spectroscopy in PBX-M. The angular momentum and the thermal ion energy transport have been studied mainly during the H mode phase of a high βp discharge (Ip approx 330 kA, 3.5 × 1019 <= ne <= 6.5 × 1019 m-3) having different heating beam configurations (combination of two perpendicular and two tangential neutral beam injections, abbreviated as 2 perp. NBI and 2 parall. NBI). The toroidal rotation velocity Vphi rises substantially in the region of r/a >= 0.5 after the L-H transition, and the Vphi profile (peakedness) is more highly dependent on the beam configuration than the Ti profile. The angular momentum confinement time varies from 147 ms (rigid rotation for 2 perp. NBI) to 39 ms (viscous rotation for 2 parall. NBI). In contrast, the thermal energy confinement time is 44-48 ms and is almost independent of the configuration. The transport analysis shows that the radial angular momentum diffusion is caused mainly by the viscous losses and that the angular momentum diffusivity χphi is reduced substantially in the outer minor radius region during the 2 perp. NBI H mode. The neoclassical friction effect between the bulk ions and the impurities may influence the χphi profiles locally, where the ion temperature gradient is steep

Injection efficiency of bound modes. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Egalon, Claudio Oliveira

1990-01-01

Previous work on efficiency of light injection into the core of a fiber from a thin film and a bulk distribution of sources in the cladding have used the fields of a weakly guiding fiber. This approximation simplifies the analysis of the power efficiency by introducing universal values for the eigenvalues of different fibers with the same V-number, but cannot predict accurately the behavior of the injected light into a fiber with arbitrary differences in indices of refraction. The exact field solution was used in the expressions of the power efficiency, p sub eff, and its behavior as a function of the fiber parameter was analyzed. Weakly guiding results obtained previously are confirmed. However, P sub eff does not always increase with the V-number but with the difference in the indices of refraction, eta sub core-eta sub clad. For the bulk distribution it was found that P sub eff increases with the wavelength, lambda, and decreases with the fiber core radius, a, i.e., it decreases with the V-number. However, for the thin film, the P sub eff remains almost constant with lambda and the fiber core radius.

A Basic Behavior of CNG DI Combustion in a Spark-Ignited Rapid Compression Machine

NASA Astrophysics Data System (ADS)

Huang, Zuohua; Shiga, Seiichi; Ueda, Takamasa; Jingu, Nobuhisa; Nakamura, Hisao; Ishima, Tsuneaki; Obokata, Tomio; Tsue, Mitsuhiro; Kono, Michikata

A basic characteristics of compressed natural gas direct-injection (CNG DI) combustion was studied by using a rapid compression machine. Results show that comparing with homogeneous mixture, CNG DI has short combustion duration, high pressure rise due to combustion, and high rate of heat release, which are considered to come from the charge stratification and the gas flow generated by the fuel injection. CNG DI can realize extremely lean combustion which reaches 0.03 equivalence ratio, φ. Combustion duration, maximum pressure rise due to combustion and combustion efficiency are found to be insensitive to the injection modes. Unburned methane showed almost the same level as that of homogeneous mixture combustion. CO increased steeply with the increase in φ when φ was greater than 0.8 due to the excessive stratification, and NOx peak value shifted to the region of lower φ. Combustion inefficiency maintains less than 0.08 in the range of φ from 0.1 to 0.9 and increases at very low φ due to bulk quenching and at higher φ due to excessive stratification. The combustion efficiency estimated from combustion products shows good agreement with that of heat release analysis.

Overview of NSTX Upgrade initial results and modelling highlights

NASA Astrophysics Data System (ADS)

Menard, J. E.; Allain, J. P.; Battaglia, D. J.; Bedoya, F.; Bell, R. E.; Belova, E.; Berkery, J. W.; Boyer, M. D.; Crocker, N.; Diallo, A.; Ebrahimi, F.; Ferraro, N.; Fredrickson, E.; Frerichs, H.; Gerhardt, S.; Gorelenkov, N.; Guttenfelder, W.; Heidbrink, W.; Kaita, R.; Kaye, S. M.; Kriete, D. M.; Kubota, S.; LeBlanc, B. P.; Liu, D.; Lunsford, R.; Mueller, D.; Myers, C. E.; Ono, M.; Park, J.-K.; Podesta, M.; Raman, R.; Reinke, M.; Ren, Y.; Sabbagh, S. A.; Schmitz, O.; Scotti, F.; Sechrest, Y.; Skinner, C. H.; Smith, D. R.; Soukhanovskii, V.; Stoltzfus-Dueck, T.; Yuh, H.; Wang, Z.; Waters, I.; Ahn, J.-W.; Andre, R.; Barchfeld, R.; Beiersdorfer, P.; Bertelli, N.; Bhattacharjee, A.; Brennan, D.; Buttery, R.; Capece, A.; Canal, G.; Canik, J.; Chang, C. S.; Darrow, D.; Delgado-Aparicio, L.; Domier, C.; Ethier, S.; Evans, T.; Ferron, J.; Finkenthal, M.; Fonck, R.; Gan, K.; Gates, D.; Goumiri, I.; Gray, T.; Hosea, J.; Humphreys, D.; Jarboe, T.; Jardin, S.; Jaworski, M. A.; Koel, B.; Kolemen, E.; Ku, S.; La Haye, R. J.; Levinton, F.; Luhmann, N.; Maingi, R.; Maqueda, R.; McKee, G.; Meier, E.; Myra, J.; Perkins, R.; Poli, F.; Rhodes, T.; Riquezes, J.; Rowley, C.; Russell, D.; Schuster, E.; Stratton, B.; Stutman, D.; Taylor, G.; Tritz, K.; Wang, W.; Wirth, B.; Zweben, S. J.

2017-10-01

The National Spherical Torus Experiment (NSTX) has undergone a major upgrade, and the NSTX Upgrade (NSTX-U) Project was completed in the summer of 2015. NSTX-U first plasma was subsequently achieved, diagnostic and control systems have been commissioned, the H-mode accessed, magnetic error fields identified and mitigated, and the first physics research campaign carried out. During ten run weeks of operation, NSTX-U surpassed NSTX record pulse-durations and toroidal fields (TF), and high-performance ~1 MA H-mode plasmas comparable to the best of NSTX have been sustained near and slightly above the n  =  1 no-wall stability limit and with H-mode confinement multiplier H98y,2 above 1. Transport and turbulence studies in L-mode plasmas have identified the coexistence of at least two ion-gyro-scale turbulent micro-instabilities near the same radial location but propagating in opposite (i.e. ion and electron diamagnetic) directions. These modes have the characteristics of ion-temperature gradient and micro-tearing modes, respectively, and the role of these modes in contributing to thermal transport is under active investigation. The new second more tangential neutral beam injection was observed to significantly modify the stability of two types of Alfven eigenmodes. Improvements in offline disruption forecasting were made in the areas of identification of rotating MHD modes and other macroscopic instabilities using the disruption event characterization and forecasting code. Lastly, the materials analysis and particle probe was utilized on NSTX-U for the first time and enabled assessments of the correlation between boronized wall conditions and plasma performance. These and other highlights from the first run campaign of NSTX-U are described.

Overview of NSTX Upgrade Initial Results and Modelling Highlights

DOE Data Explorer

Menard, J.E. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000312923286); Allain, J.P.; Battaglia, D.J. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000188979740); Bedoya, F.; Bell, R.E. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:000000019544498X); Belova, E. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000215251027); Berkery, J.W. [Columbia University, New York, NY, United States of America; Boyer, M.D. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000268459155); Crocker, N.; Diallo, A. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:000000020706060X); Ebrahimi, F. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000331095367); Ferraro, N. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000263487827); Fredrickson, E. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Frerichs, H.; Gerhardt, S. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000225462194); Gorelenkov, N. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Guttenfelder, W. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:000000018181058X); Heidbrink, W.; Kaita, R. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000285159824); Kaye, S.M. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Kriete, D.M.; Kubota, S.; LeBlanc, B.P. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000314550129); Liu, D. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000191747078); Lunsford, R. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000335886801); Mueller, D. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000224563356); Myers, C.E.; Ono, M. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Park, J-K. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000324198667); Podesta, M. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000349750585); Raman, R. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000220273271); Reinke, M.; Ren, Y. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000198316035); Sabbagh, S.A.; Schmitz, O.; Scotti, F. [Lawrence Livermore National Laboratory, Livermore, CA, United States of America; Sechrest, Y.; Skinner, C.H. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Smith, D.R. [University of Wisconsin, Madison, WI, United States of America; Soukhanovskii, V.; Stoltzfus-Dueck, T. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000325876298); Yuh, H.; Wang, Z. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Waters, I.; Ahn, J-W.; Andre, R.; Barchfield, R.; Beiersdorfer, P.; Bertelli, N. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000293267585); Bhattacharjee, A. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000164110178); Boyle, D. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000180918169); Brennan, D.; Buttery, R.; Capece, A. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000341477174); Canal, G.; Canik, J.; Chang, C.S. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000233465731); Darrow, D. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Delgado-Aparicio, L. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000167394380); Domier, C.; Ethier, S. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Evans, T.; Ferron, J.; Finkenthal, M.; Fonck, R.; Gan, K.; Gates, D. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000156793124); Goumiri, I. [University of Wisconsin, Madison, WI, United States of America; Gray, T.; Hosea, J. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Humphreys, D.; Jarboe, T.; Jardin, S. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000163906908); Jaworski, M.A. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Koel, B.; Kolemen, E. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000342123247); Ku, S. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000299641208); LaHaye, R.J.; Levinton, F.; Luhmann Jr., N.; Maingi, R. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000312388121); Maqueda, R. [X Science LLC, Plainsboro, NJ, United States of America; McKee, G.; Meier, E.; Myra, J.; Perkins, R. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000272160201); Poli, F. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000339594371); Rhodes, T.; Riquezes, J.; Rowley, C. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000290995739); Russell, D.; Schuster, E.; Stratton, B. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Stutman, D.; Taylor, G. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000258487152); Tritz, K. [Johns Hopkins University, Baltimore, MD, United States of America; Wang, W. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Wirth, B.; Zweben, S.J. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000217380586)

2017-01-01

The National Spherical Torus Experiment (NSTX) has undergone a major upgrade, and the NSTX Upgrade (NSTX-U) Project was completed in the summer of 2015. NSTX-U first plasma was subsequently achieved, diagnostic and control systems have been commissioned, H-Mode accessed, magnetic error fields identified and mitigated, and the first physics research campaign carried out. During 10 run weeks of operation, NSTX-U surpassed NSTX-record pulse-durations and toroidal fields, and high-performance ~1MA H-mode plasmas comparable to the best of NSTX have been sustained near and slightly above the n=1 no-wall stability limit and with H-mode confinement multiplier H98y2 above 1. Transport and turbulence studies in L-mode plasmas have identified the coexistence of at least two ion-gyro-scale turbulent micro-instabilities near the same radial location but propagating in opposite (i.e. ion and electron diamagnetic) directions. These modes have the characteristics of ion-temperature gradient and micro-tearing modes, respectively, and the role of these modes in contributing to thermal transport is under active investigation. The new second more tangential neutral beam injection was observed to significantly modify the stability of two types of Alfven Eigenmodes. Improvements in offline disruption forecasting were made in the areas of identification of rotating MHD modes and other macroscopic instabilities using the Disruption Event Characterization and Forecasting (DECAF) code. Lastly, the Materials Analysis and Particle Probe (MAPP) was utilized on NSTX-U for the first time and enabled assessments of the correlation between boronized wall conditions and plasma performance. These and other highlights from the first run campaign of NSTX-U are described.

Overview of NSTX Upgrade initial results and modelling highlights

DOE PAGES

Menard, J. E.; Allain, J. P.; Battaglia, D. J.; ...

2017-06-20

The National Spherical Torus Experiment (NSTX) has undergone a major upgrade, and the NSTX Upgrade (NSTX-U) Project was completed in the summer of 2015. NSTX-U first plasma was subsequently achieved, diagnostic and control systems have been commissioned, the H-mode accessed, magnetic error fields identified and mitigated, and the first physics research campaign carried out. During ten run weeks of operation, NSTX-U surpassed NSTX record pulse-durations and toroidal fields (TF), and high-performance ~1 MA H-mode plasmas comparable to the best of NSTX have been sustained near and slightly above the n = 1 no-wall stability limit and with H-mode confinement multipliermore » H 98y,2 above 1. Transport and turbulence studies in L-mode plasmas have identified the coexistence of at least two ion-gyro-scale turbulent micro-instabilities near the same radial location but propagating in opposite (i.e. ion and electron diamagnetic) directions. These modes have the characteristics of ion-temperature gradient and micro-tearing modes, respectively, and the role of these modes in contributing to thermal transport is under active investigation. The new second more tangential neutral beam injection was observed to significantly modify the stability of two types of Alfven eigenmodes. Improvements in offline disruption forecasting were made in the areas of identification of rotating MHD modes and other macroscopic instabilities using the disruption event characterization and forecasting code. Finally, the materials analysis and particle probe was utilized on NSTX-U for the first time and enabled assessments of the correlation between boronized wall conditions and plasma performance. These and other highlights from the first run campaign of NSTX-U are described.« less

Overdense microwave plasma heating in the CNT stellarator

NASA Astrophysics Data System (ADS)

Hammond, K. C.; Diaz-Pacheco, R. R.; Köhn, A.; Volpe, F. A.; Wei, Y.

2018-02-01

Overdense plasmas have been attained with 2.45 GHz microwave heating in the low-field, low-aspect-ratio CNT stellarator. Densities higher than four times the ordinary (O) mode cutoff density were measured with 8 kW of power injected in the O-mode and, alternatively, with 6.5 kW in the extraordinary (X) mode. The temperature profiles peak at the plasma edge. This was ascribed to collisional damping of the X-mode at the upper hybrid resonant layer. The X-mode reaches that location by tunneling, mode-conversions or after polarization-scrambling reflections off the wall and in-vessel coils, regardless of the initial launch being in O- or X-mode. This interpretation was confirmed by full-wave numerical simulations. Also, as the CNT plasma is not completely ionized at these low microwave power levels, electron density was shown to increase with power. A dependence on magnetic field strength was also observed, for O-mode launch.

All-fiber orbital angular momentum mode generation and transmission system

NASA Astrophysics Data System (ADS)

Heng, Xiaobo; Gan, Jiulin; Zhang, Zhishen; Qian, Qi; Xu, Shanhui; Yang, Zhongmin

2017-11-01

We proposed and demonstrated an all-fiber system for generating and transmitting orbital angular momentum (OAM) mode light. A specially designed multi-core fiber (MCF) was used to endow with guide modes different phase change and two tapered transition regions were used for providing low-loss interfaces between different fiber structures. By arranging the refractive index distribution among the multi-cores and controlling the length of MCF, which essentially change the phase difference between the neighboring cores, OAM modes with different topological charge l can be generated selectively. Through two tapered transition regions, the non-OAM mode light can be effectively injected into the MCF and the generated OAM mode light can be easily launched into OAM mode supporting fiber for long distance and high purity transmission. Such an all-fiber OAM mode generation and transmission system owns the merits of flexibility, compactness, portability, and would have practical application value in OAM optical fiber communication systems.

Feasibility study of ECRH in NSTX-U startup plasma

NASA Astrophysics Data System (ADS)

Lopez, N. A.; Poli, F.; Taylor, G.; Harvey, R.; Petrov, Yu.

2016-10-01

A key mission goal of the National Spherical Torus eXperiment Upgrade (NSTX-U) is the demonstration of fully non-inductive startup and operation. In part to accomplish this, a 1MW, 28 GHz ECRH system is presently being developed for implementation on NSTX-U in 2018. Like most spherical tokamaks, NSTX-U operates in the overdense regime (fpe>fce) , which limits traditional ECRH to the early startup phase. An extensive modelling effort of the propagation and absorption of EC waves in the evolving plasma is thus required to define the most effective window of operation, and to optimize the launcher geometry for maximal heating and for current drive during this window. In fact, the ECRH system will play an important role in preparing a target plasma for subsequent injection of IC waves and NBI. Here we assess the feasibility of O1-mode ECRH in NSTX-U startup plasma at full field of 1T through time-dependent simulations performed with the transport solver TRANSP. Linear ray-tracing calculations conducted by GENRAY are coupled into the TRANSP framework, allowing the plasma equilibrium and the temperature profiles to evolve self-consistently in response to the injected microwave power. Furthermore, we investigate additional possibilities of heating and current drive made available through coupling the injected O-mode power to the electrostatic EBW via the slow X-mode as an intermediary.

Isotope-dilution gas chromatography-mass spectrometry coupled with injection-port butylation for the determination of 4-t-octylphenol, 4-nonylphenols and bisphenol A in human urine.

PubMed

Chung, Shuang-Hung; Ding, Wang-Hsien

2018-02-05

An analytical method that utilizes isotope-dilution gas chromatography-mass spectrometry (ID-GC-MS) coupled with injection-port butylation was developed. The method was validated, and confirmed to be able to determine the presence of three commonly detected endocrine-disrupting chemicals (EDCs: 4-tert-octylphenol (4-t-OP), 4-nonylphenols (4-NPs) and bisphenol A (BPA)) in human urine with high precision and accuracy. After sample preparation by solid-phase extraction, the extract was introduced into GC-MS via injection-port butylation. The butylated target analytes were identified and quantified by using ion-trap mass spectrometry operating in the selected-ion-storage mode, and employing the measurement of peak area ratios of the butylated target analytes and labeled-analogues in the samples and calibration standards. The labeled-analogues were also used to correct the variations associated with the analysis and matrix effect. The limits of quantitation (LOQs) ranged from 0.1 to 0.3ng/mL. High precisions for both intra- and inter-day analysis ranged from 1 to 6%, and excellent accuracy (mean recovery) ranged from 92 to 105% on two concentration levels. In human urine, the total concentrations of three selected EDCs varied from 1.28 to 7.14ng/mL. 4-NPs were detected within all collected samples. The developed method allows accurate analysis of trace-level of EDCs in urine, and these target EDCs could act as useful biomarkers to assess exposure in biomonitoring studies and programs. Copyright © 2017 Elsevier B.V. All rights reserved.

Study of matrix effects on the direct trace analysis of acidic pesticides in water using various liquid chromatographic modes coupled to tandem mass spectrometric detection.

PubMed

Dijkman, E; Mooibroek, D; Hoogerbrugge, R; Hogendoorn, E; Sancho, J V; Pozo, O; Hernández, F

2001-08-10

This study investigated the effects of matrix interferences on the analytical performance of a triple quadrupole mass spectrometric (MS-MS) detector coupled to various reversed-phase liquid chromatographic (LC) modes for the on-line determination of various types of acidic herbicides in water using external calibration for quantification of the analytes tested at a level of 0.4 microg/l. The LC modes included (i) a single-column configuration (LC), (ii) precolumn switching (PC-LC) and (iii) coupled-column LC (LC-LC). As regards detection, electrospray (ESI) and atmospheric pressure chemical ionization (APCI) in both positive (PI) and negative (NI) ionization modes were examined. Salinity and dissolved organic carbon (DOC) were selected as interferences to study matrix effects in this type of analysis. Therefore, Milli-Q and tap water samples both fortified with 12 mg/l DOC and spiked with sulfometuron-methyl, bentazone, bromoxynil, 2-methyl-4-chlorophenoxyacetic acid, and 2-methyl-4-chlorophenoxypropionic acid at a level of about 0.4 microg/l were analyzed with the various LC-MS approaches. Direct sample injection was performed with volumes of 0.25 ml or 2.0 ml on a column of 2.1 mm I.D. or 4.6 mm I.D. for the ESI and APCI modes, respectively. The recovery data were used to compare and evaluate the analytical performance of the various LC approaches. As regards matrix effects, the salinity provided a dramatic decrease in response for early eluting analytes (k value of about 1) when using the LC mode. Both PC-LC and LC-LC efficiently eliminated this problem. The high DOC content hardly effected the responses of analytes in the ESI mode, while in most cases the responses increased when using APCI-MS-MS detection. Of all the tested configurations, LC-LC-ESI-MS-MS with the column combination Discovery C18/ABZ+ was the most favorable as regards elimination of matrix effects and provided reliable quantification of all compounds using external calibration at the tested low level. The major observed effects were verified with statistical evaluation of the data employing backwards ordinary least-square regression. All tested column-switching modes hyphenated to ESI- or APCI-MS-MS allowed the on-line multi-residue analysis of acidic pesticides in the reference water down to a level of 0.1 microg/l in less than 10 min, emphasizing the feasibility of such an approach in this field of analysis.

Predicting ESI/MS Signal Change for Anions in Different Solvents.

PubMed

Kruve, Anneli; Kaupmees, Karl

2017-05-02

LC/ESI/MS is a technique widely used for qualitative and quantitative analysis in various fields. However, quantification is currently possible only for compounds for which the standard substances are available, as the ionization efficiency of different compounds in ESI source differs by orders of magnitude. In this paper we present an approach for quantitative LC/ESI/MS analysis without standard substances. This approach relies on accurately predicting the ionization efficiencies in ESI source based on a model, which uses physicochemical parameters of analytes. Furthermore, the model has been made transferable between different mobile phases and instrument setups by using a suitable set of calibration compounds. This approach has been validated both in flow injection and chromatographic mode with gradient elution.

UHPLC-Q-TOF-MS-based metabolomics approach to compare the saponin compositions of Xueshuantong injection and Xuesaitong injection.

PubMed

Yao, Changliang; Yang, Wenzhi; Zhang, Jingxian; Qiu, Shi; Chen, Ming; Shi, Xiaojian; Pan, Huiqin; Wu, Wanying; Guo, Dean

2017-02-01

Various traditional Chinese medicine preparations developed from Notoginseng total saponins, including Xueshuantong injection and Xuesaitong injection, are extensively used in China to treat cardiocerebrovascular diseases. However, the difference of their saponin compositions remains unknown. An ultra high performance liquid chromatography with quadrupole time-of-flight mass spectrometry based metabolomics approach was developed to probe the saponin discrimination between Xueshuantong and Xuesaitong and the related factors by large sample analysis. A highly efficient chromatographic separation was achieved on an HSS T3 column within 20 min with the holistic metabolites information recorded in the negative MS E mode. A six-step data pretreatment procedure mainly based on Progenesis QI and mass defect filtering was established. Pattern recognition chemometrics was used to discover the potential saponin markers. The saponin composition of Wuzhou Xueshuantong showed distinct discrimination from the other products. Wuzhou Xueshuantong contains more abundant protopanaxatriol-type noto-R 1 , Rg 1 , Re, and protopanaxadiol-type Rb 1 , but less Rd and other low-polarity protopanaxadiol-type ginsenosides. These differences could not directly correlate to the use of different parts of Panax notoginseng, but possibly to the different preparation techniques employed by different manufacturers. These results are beneficial to the establishment of pharmacopoeia standards and the assessment of the efficacy and adverse drug reactions for these homologous products. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Shear Alfven Wave Injection in the Magnetosphere by Ionospheric Modifications in the Absence of Electrojet Currents

NASA Astrophysics Data System (ADS)

Papadopoulos, K.; Eliasson, B.; Shao, X.; Labenski, J.; Chang, C.

2011-12-01

A new concept of generating ionospheric currents in the ULF/ELF range with modulated HF heating using ground-based transmitters even in the absence of electrojet currents is presented. The new concept relies on using HF heating of the F-region to modulate the electron temperature and has been given the name Ionospheric Current Drive (ICD). In ICD, the pressure gradient associated with anomalous or collisional F-region electron heating drives a local diamagnetic current that acts as an antenna to inject mainly Magneto-Sonic (MS) waves in the ionospheric plasma. The electric field associated with the MS wave drives Hall currents when it reaches the E region of the ionosphere. The Hall currents act as a secondary antenna that inject waves in the Earth-Ionosphere Waveguide (EIW) below and shear Alfven waves or EMIC waves upwards towards the conjugate regions. The paper presents: (i) Theoretical results using a cold Hall MHD model to study ICD and the generation of ULF/ELF waves by the modulation of the electron pressure at the F2-region with an intense HF electromagnetic wave. The model solves equations governing the dynamics of the shear Alfven and magnetosonic modes, of the damped modes in the diffusive Pedersen layer, and of the weakly damped helicon wave mode in the Hall-dominated E-region. The model incorporates realistic profile of the ionospheric conductivities and magnetic field configuration. We use the model to simulate propagation and dynamics of the low-frequency waves and their injection into the magnetosphere from the HAARP and Arecibo ionospheric heaters. (ii) Proof of principle experiments using the HAARP ionospheric heater in conjunction with measurements by the DEMETER satellite This work is supported by ONR MURI grant and DARPA BRIOCHE Program

Demonstrating ultrafast polarization dynamics in spin-VCSELs

NASA Astrophysics Data System (ADS)

Lindemann, Markus; Pusch, Tobias; Michalzik, Rainer; Gerhardt, Nils C.; Hofmann, Martin R.

2018-02-01

Vertical-cavity surface-emitting lasers (VCSELs) are used for short-haul optical data transmission with increasing bit rates. The optimization involves both enhanced device designs and the use of higher-order modulation formats. In order to improve the modulation bandwidth substantially, the presented work employs spin-pumped VCSELs (spin-VCSELs) and their polarization dynamics instead of relying on intensity-modulated devices. In spin-VCSELs, the polarization state of the emitted light is controllable via spin injection. By optical spin pumping a single-mode VCSEL is forced to emit light composed of both orthogonal linearly polarized fundamental modes. The frequencies of these two modes differ slightly by a value determined by the cavity birefringence. As a result, the circular polarization degree oscillates with their beat frequency, i.e., with the birefringence-induced mode splitting. We used this phenomenon to show so-called polarization oscillations, which are generated by pulsed spin injection. Their frequency represents the polarization dynamics resonance frequency and can be tuned over a wide range via the birefringence, nearly independent from any other laser parameter. In previous work we demonstrated a maximum birefringence-induced mode splitting of more than 250 GHz. In this work, compared to previous publications, we show an almost doubled polarization oscillation frequency of more than 80 GHz. Furthermore, we discuss concepts to achieve even higher values far above 100 GHz.

Observation of finite-. beta. MHD phenomena in tokamaks

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

McGuire, K.M.

1984-09-01

Stable high-beta plasmas are required for the tokamak to attain an economical fusion reactor. Recently, intense neutral beam heating experiments in tokamaks have shown new effects on plasma stability and confinement associated with high beta plasmas. The observed spectrum of MHD fluctuations at high beta is clearly dominated by the n = 1 mode when the q = 1 surface is in the plasma. The m/n = 1/1 mode drives other n = 1 modes through toroidal coupling and n > 1 modes through nonlinear coupling. On PDX, with near perpendicular injection, a resonant interaction between the n = 1more » internal kink and the trapped fast ions results in loss of beam particles and heating power. Key parameters in the theory are the value of q/sub 0/ and the injection angle. High frequency broadband magnetic fluctuations have been observed on ISX-B and D-III and a correlation with the deterioration of plasma confinement was reported. During enhanced confinement (H-mode) discharges in divertor plasmas, two new edge instabilities were observed, both localized radially near the separatrix. By assembling results from the different tokamak experiments, it is found that the simple theoretical ideal MHD beta limit has not been exceeded. Whether this represents an ultimate tokamak limit or if beta optimized configurations (Dee- or bean-shaped plasmas) can exceed this limit and perhaps enter a second regime of stability remains to be clarified.« less

Sensitivity of gravitational wave searches to the full signal of intermediate-mass black hole binaries during the first observing run of Advanced LIGO

NASA Astrophysics Data System (ADS)

Calderón Bustillo, Juan; Salemi, Francesco; Dal Canton, Tito; Jani, Karan P.

2018-01-01

The sensitivity of gravitational wave searches for binary black holes is estimated via the injection and posterior recovery of simulated gravitational wave signals in the detector data streams. When a search reports no detections, the estimated sensitivity is then used to place upper limits on the coalescence rate of the target source. In order to obtain correct sensitivity and rate estimates, the injected waveforms must be faithful representations of the real signals. Up to date, however, injected waveforms have neglected radiation modes of order higher than the quadrupole, potentially biasing sensitivity and coalescence rate estimates. In particular, higher-order modes are known to have a large impact in the gravitational waves emitted by intermediate-mass black holes binaries. In this work, we evaluate the impact of this approximation in the context of two search algorithms run by the LIGO Scientific Collaboration in their search for intermediate-mass black hole binaries in the O1 LIGO Science Run data: a matched filter-based pipeline and a coherent unmodeled one. To this end, we estimate the sensitivity of both searches to simulated signals for nonspinning binaries including and omitting higher-order modes. We find that omission of higher-order modes leads to biases in the sensitivity estimates which depend on the masses of the binary, the search algorithm, and the required level of significance for detection. In addition, we compare the sensitivity of the two search algorithms across the studied parameter space. We conclude that the most recent LIGO-Virgo upper limits on the rate of coalescence of intermediate-mass black hole binaries are conservative for the case of highly asymmetric binaries. However, the tightest upper limits, placed for nearly equal-mass sources, remain unchanged due to the small contribution of higher modes to the corresponding sources.

Single Longitudinal Mode, High Repetition Rate, Q-switched Ho:YLF Laser for Remote Sensing

NASA Technical Reports Server (NTRS)

Bai, Yingxin; Yu, Jirong; Petzar, Paul; Petros, M.; Chen, Songsheng; Trieu, Bo; Lee, Nyung; Singh, U.

2009-01-01

Ho:YLF/LuLiF lasers have specific applications for remote sensing such as wind-speed measurement and carbon dioxide (CO2) concentration measurement in the atmosphere because the operating wavelength (around 2 m) is located in the eye-safe range and can be tuned to the characteristic lines of CO2 absorption and there is strong backward scattering signal from aerosol (Mie scattering). Experimentally, a diode pumped Ho:Tm:YLF laser has been successfully used as the transmitter of coherent differential absorption lidar for the measurement of with a repetition rate of 5 Hz and pulse energy of 75 mJ [1]. For highly precise CO2 measurements with coherent detection technique, a laser with high repetition rate is required to averaging out the speckle effect [2]. In addition, laser efficiency is critically important for the air/space borne lidar applications, because of the limited power supply. A diode pumped Ho:Tm:YLF laser is difficult to efficiently operate in high repetition rate due to the large heat loading and up-conversion. However, a Tm:fiber laser pumped Ho:YLF laser with low heat loading can be operated at high repetition rates efficiently [3]. No matter whether wind-speed or carbon dioxide (CO2) concentration measurement is the goal, a Ho:YLF/LuLiF laser as the transmitter should operate in a single longitudinal mode. Injection seeding is a valid technique for a Q-switched laser to obtain single longitudinal mode operation. In this paper, we will report the new results for a single longitudinal mode, high repetition rate, Q-switched Ho:YLF laser. In order to avoid spectral hole burning and make injection seeding easier, a four mirror ring cavity is designed for single longitudinal mode, high repetition rate Q-switched Ho:YLF laser. The ramp-fire technique is chosen for injection seeding.

Characterizing SRAM Single Event Upset in Terms of Single and Double Node Charge Collection

NASA Technical Reports Server (NTRS)

Black, J. D.; Ball, D. R., II; Robinson, W. H.; Fleetwood, D. M.; Schrimpf, R. D.; Reed, R. A.; Black, D. A.; Warren, K. M.; Tipton, A. D.; Dodd, P. E.;

Investigation of Physical Processes Limiting Plasma Density in DIII--D

NASA Astrophysics Data System (ADS)

Maingi, R.

1996-11-01

Understanding the physical processes which limit operating density is crucial in achieving peak performance in confined plasmas. Studies from many of the world's tokamaks have indicated the existence(M. Greenwald, et al., Nucl. Fusion 28) (1988) 2199 of an operational density limit (Greenwald limit, n^GW_max) which is proportional to the plasma current and independent of heating power. Several theories have reproduced the current dependence, but the lack of a heating power dependence in the data has presented an enigma. This limit impacts the International Thermonuclear Experimental Reactor (ITER) because the nominal operating density for ITER is 1.5 × n^GW_max. In DIII-D, experiments are being conducted to understand the physical processes which limit operating density in H-mode discharges; these processes include X-point MARFE formation, high core recycling and neutral pressure, resistive MHD stability, and core radiative collapse. These processes affect plasma properties, i.e. edge/scrape-off layer conduction and radiation, edge pressure gradient and plasma current density profile, and core radiation, which in turn restrict the accessible density regime. With divertor pumping and D2 pellet fueling, core neutral pressure is reduced and X-point MARFE formation is effectively eliminated. Injection of the largest-sized pellets does cause transient formation of divertor MARFEs which occasionally migrate to the X-point, but these are rapidly extinguished in pumped discharges in the time between pellets. In contrast to Greenwald et al., it is found that the density relaxation time after pellets is largely independent of the density relative to the Greenwald limit. Fourier analysis of Mirnov oscillations indicates the de-stabilization and growth of rotating, tearing-type modes (m/n= 2/1) when the injected pellets cause large density perturbations, and these modes often reduce energy confinement back to L-mode levels. We are examining the mechanisms for de-stabilization of the mode, the primary ones being neo-classical pressure gradient drivers. Discharges with a gradual density increase are often free of large amplitude tearing modes, allowing access to the highest density regimes in which off-axis beam deposition can lead to core radiative collapse, i.e. a central power balance limit. The highest achieved barne was 1.5 × n^GW_max with τ_E/τ_E^JET-DIII-D >= 0.9. The highest density obtained in L-mode discharges was 3 × n^GW_max. Implications of these results for ITER will be discussed.

Function of CN group in organic sensitizers: The first principle study.

PubMed

Liu, Yun; Shao, Di; Bai, Xiaohui; Yang, Zhenqing; Lin, Chundan; Shao, Changjin

2017-05-15

The cyano group (CN) of the acceptor in organic sensitizers plays an important role for highly efficient dye-sensitized solar cells. In this paper, three 5, 6-difluoro-2,1,3-benzothiadiazole (DFBTD) organic molecules with different number of CN units, named ME15, ME16 and ME17, were investigated by the density functional theory (DFT) and time-dependent DFT (TDDFT). We analyzed the CNs effects on the electronic structures, optical properties, adsorption modes and electron transfer and injection. The result shows that ME17 has the largest maximum absorption wavelength (λ max ) among these new designed dyes due to the strong electron withdrawing ability of two CNs. In addition, CN greatly influence the adsorption modes of dye/TiO 2 and electron injection mechanism. ME16 with one CN also has good optical absorption properties and its acceptor has the strongest coupling strength with the TiO 2 semiconductor which is favorable for electron transfer and injection. Thus, we believe that the number of CN groups in acceptor should be moderate and one CN in D-A-π-A structure dyes may be the more appropriate focusing on the light harvesting ability, electron transfer and electron injection. Copyright © 2017 Elsevier B.V. All rights reserved.

INTERNATIONAL CONFERENCE ON SEMICONDUCTOR INJECTION LASERS SELCO-87: Line width of a single longitudinal mode emitted by an AlGaAs heterojunction laser

NASA Astrophysics Data System (ADS)

Bogatov, Alexandr P.; Eliseev, P. G.; Luk'yanov, S. A.; Pak, G. T.; Petrakova, T. V.

1988-11-01

A nonmonotonic dependence of the emission line width on the power was observed for a single longitudinal mode of an AlGaAs heterojunction laser. This behavior could be due to the dependence of the waveguide coefficient of the amplitude-phase coupling on the nature of operation of the laser.

New mode of operating a magnetized coaxial plasma gun for injecting magnetic helicity into a spheromak.

PubMed

Woodruff, S; Hill, D N; Stallard, B W; Bulmer, R; Cohen, B; Holcomb, C T; Hooper, E B; McLean, H S; Moller, J; Wood, R D

2003-03-07

By operating a magnetized coaxial plasma gun continuously with just sufficient current to enable plasma ejection, large gun-voltage spikes (approximately 1 kV) are produced, giving the highest sustained voltage approximately 500 V and highest sustained helicity injection rate observed in the Sustained Spheromak Physics Experiment. The spheromak magnetic field increases monotonically with time, exhibiting the lowest fluctuation levels observed during formation of any spheromak (B/B>/=2%). The results suggest an important mechanism for field generation by helicity injection, namely, the merging of helicity-carrying filaments.

Demonstration of ultra-wideband (UWB) over fiber based on optical pulse-injected semiconductor laser.

PubMed

Juan, Yu-Shan; Lin, Fan-Yi

2010-04-26

We experimentally demonstrated the ultra-wideband (UWB) signal generation utilizing nonlinear dynamics of an optical pulse-injected semiconductor laser. The UWB signals generated are fully in compliant with the FCC mask for indoor radiation, while a large fractional bandwidth of 93% is achieved. To show the feasibility of UWB-over-fiber, transmission over a 2 km single-mode fiber and a wireless channel utilizing a pair of broadband antennas are examined. Moreover, proof of concept experiment on data encoding and decoding with 250 Mb/s in the optical pulse-injected laser is successfully demonstrated.

Quantum correlation in degenerate optical parametric oscillators with mutual injections

NASA Astrophysics Data System (ADS)

Takata, Kenta; Marandi, Alireza; Yamamoto, Yoshihisa

2015-10-01

We theoretically and numerically study the quantum dynamics of two degenerate optical parametric oscillators with mutual injections. The cavity mode in the optical coupling path between the two oscillator facets is explicitly considered. Stochastic equations for the oscillators and mutual injection path based on the positive P representation are derived. The system of two gradually pumped oscillators with out-of-phase mutual injections is simulated, and its quantum state is investigated. When the incoherent loss of the oscillators other than the mutual injections is small, the squeezed quadratic amplitudes p ̂ in the oscillators are positively correlated near the oscillation threshold. It indicates finite quantum correlation, estimated via Gaussian quantum discord, and the entanglement between the intracavity subharmonic fields. When the loss in the injection path is low, each oscillator around the phase transition point forms macroscopic superposition even under a small pump noise. It suggests that the squeezed field stored in the low-loss injection path weakens the decoherence in the oscillators.

Orthogonal control of the frequency comb dynamics of a mode-locked laser diode.

PubMed

Holman, Kevin W; Jones, David J; Ye, Jun; Ippen, Erich P

2003-12-01

We have performed detailed studies on the dynamics of a frequency comb produced by a mode-locked laser diode (MLLD). Orthogonal control of the pulse repetition rate and the pulse-to-pulse carrier-envelope phase slippage is achieved by appropriate combinations of the respective error signals to actuate the diode injection current and the saturable absorber bias voltage. Phase coherence is established between the MLLD at 1550 nm and a 775-nm mode-locked Ti:sapphire laser working as part of an optical atomic clock.

Impurity screening behavior of the high-field side scrape-off layer in near-double-null configurations: prospect for mitigating plasma-material interactions on RF actuators and first-wall components

NASA Astrophysics Data System (ADS)

LaBombard, B.; Kuang, A. Q.; Brunner, D.; Faust, I.; Mumgaard, R.; Reinke, M. L.; Terry, J. L.; Howard, N.; Hughes, J. W.; Chilenski, M.; Lin, Y.; Marmar, E.; Rice, J. E.; Rodriguez-Fernandez, P.; Wallace, G.; Whyte, D. G.; Wolfe, S.; Wukitch, S.

2017-07-01

The impurity screening response of the high-field side (HFS) scrape-off layer (SOL) to localized nitrogen injection is investigated on Alcator C-Mod for magnetic equilibria spanning lower-single-null, double-null and upper-single-null configurations under otherwise identical plasma conditions. L-mode, EDA H-mode and I-mode discharges are investigated. HFS impurity screening is found to depend on magnetic flux balance and the direction of B  ×  \

Turbulent particle transport as a function of toroidal rotation in DIII-D H-mode plasmas

DOE PAGES

Wang, Xin; Mordijck, Saskia; Zeng, Lei; ...

2016-03-01

In this paper we show how changes in toroidal rotation, by controlling the injected torque, affect particle transport and confinement. The toroidal rotation is altered using the co- and counter neutral beam injection (NBI) in low collisionality H-mode plasmas on DIII-D with dominant electron cyclotron heating (ECH). We find that there is no correlation between the toroidal rotation shear and the inverse density gradient, which is observed on AUG whenmore » $${{T}_{\\text{e}}}/{{T}_{\\text{i}}}$$ is varied using ECH (Angioni et al 2011 Phys. Rev. Lett. 107 215003). In DIII-D, we find that in a discharge with balanced torque injection, the $$E\\times B$$ shear is smaller than the linear gyrokinetic growth rate for small $${{k}_{\\theta}}{{\\rho}_{s}}$$ for $$\\rho =0.6$$ –0.85. This results in lower particle confinement. In the co- and counter- injected discharges the $$E\\times B$$ shear is larger or close to the linear growth rate at the plasma edge and both configurations have higher particle confinement. In order to measure particle transport, we use a small periodic perturbative gas puff. This gas puff perturbs the density profiles and allows us to extract the perturbed diffusion and inward pinch coefficients. We observe a strong increase in the inward particle pinch in the counter-torque injected plasma. Lastly, the calculated quasi-linear particle flux, nor the linear growth rates using TGLF agree with experimental observations.« less

Top-up operation at Pohang Light Source-II

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

Hwang, I.; Huang, J. Y.; Kim, M.

2014-05-15

After three years of upgrading work, PLS-II (S. Shin, Commissioning of the PLS-II, JINST, January 2013) is now successfully operating. The top-up operation of the 3 GeV linear accelerator had to be delayed because of some challenges encountered, and PLS-II was run in decay mode at the beginning in March 2012. The main difficulties encountered in the top-up operation of PLS-II are different levels between the linear accelerator and the storage ring, the 14 narrow gap in-vacuum undulators in operation, and the full energy injection by 3 GeV linear accelerator. Large vertical emittance and energy jitter of the linac weremore » the major obstacles that called for careful control of injected beam to reduce beam loss in the storage ring during injection. The following measures were taken to resolve these problems: (1) The high resolution Libera BPM (see http://www.i-tech.si ) was implemented to measure the beam trajectory and energy. (2) Three slit systems were installed to filter the beam edge. (3) De-Qing circuit was applied to the modulator system to improve the energy stability of injected beam. As a result, the radiation by beam loss during injection is reduced drastically, and the top-up mode has been successfully operating since 19th March 2013. In this paper, we describe the experimental results of the PLS-II top-up operation and the improvement plan.« less

Modeling of a sensitive time-of-flight flash LiDAR system

NASA Astrophysics Data System (ADS)

Fathipour, V.; Wheaton, S.; Johnson, W. E.; Mohseni, H.

2016-09-01

used for monitoring and profiling structures, range, velocity, vibration, and air turbulence. Remote sensing in the IR region has several advantages over the visible region, including higher transmitter energy while maintaining eye-safety requirements. Electron-injection detectors are a new class of detectors with high internal avalanche-free amplification together with an excess-noise-factor of unity. They have a cutoff wavelength of 1700 nm. Furthermore, they have an extremely low jitter. The detector operates in linear-mode and requires only bias voltage of a few volts. This together with the feedback stabilized gain mechanism, makes formation of large-format high pixel density electron-injection FPAs less challenging compared to other detector technologies such as avalanche photodetectors. These characteristics make electron-injection detectors an ideal choice for flash LiDAR application with mm scale resolution at longer ranges. Based on our experimentally measured device characteristics, a detailed theoretical LiDAR model was developed. In this model we compare the performance of the electron-injection detector with commercially available linear-mode InGaAs APD from (Hamamatsu G8931-20) as well as a p-i-n diode (Hamamatsu 11193 p-i-n). Flash LiDAR images obtained by our model, show the electron-injection detector array (of 100 x 100 element) achieves better resolution with higher signal-to-noise compared with both the InGaAs APD and the p-i-n array (of 100 x 100 element).

Mode Hopping in Semiconductor Lasers

NASA Astrophysics Data System (ADS)

Heumier, Timothy Alan

Semiconductor lasers have found widespread use in fiberoptic communications, merchandising (bar-code scanners), entertainment (videodisc and compact disc players), and in scientific inquiry (spectroscopy, laser cooling). Some uses require a minimum degree of stability of wavelength which is not met by these lasers: Under some conditions, semiconductor lasers can discontinuously switch wavelengths in a back-and-forth manner. This is called mode hopping. We show that mode hopping is directly correlated to noise in the total intensity, and that this noise is easily detected by a photodiode. We also show that there are combinations of laser case temperature and injection current which lead to mode hopping. Conversely, there are other combinations for which the laser is stable. These results are shown to have implications for controlling mode hopping.

Lithium granule ablation and penetration during ELM pacing experiments at DIII-D

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

Lunsford, R.; Bortolon, A.; Roquemore, A. L.

At DIII-D, lithium granules were radially injected into the plasma at the outer midplane to trigger and pace edge localized modes (ELMs). Granules ranging in size from 300 to 1000 microns were horizontally launched into H-mode discharges with velocities near 100 m/s, and granule to granule injection frequencies less than 500 Hz. While the smaller granules were only successful in triggering ELMs approximately 20% of the time, the larger granules regularly demonstrated ELM triggering efficiencies of greater than 80%. A fast visible camera looking along the axis of injection observed the ablation of the lithium granules. We used the durationmore » of ablation as a benchmark for a neutral gas shielding calculation, and approximated the ablation rate and mass deposition location for the various size granules, using measured edge plasma profiles as inputs. In conclusion, this calculation suggests that the low triggering efficiency of the smaller granules is due to the inability of these granules to traverse the steep edge pressure gradient region and reach the top of the pedestal prior to full ablation.« less

Lithium granule ablation and penetration during ELM pacing experiments at DIII-D

DOE PAGES

Lunsford, R.; Bortolon, A.; Roquemore, A. L.; ...

2016-05-25

At DIII-D, lithium granules were radially injected into the plasma at the outer midplane to trigger and pace edge localized modes (ELMs). Granules ranging in size from 300 to 1000 microns were horizontally launched into H-mode discharges with velocities near 100 m/s, and granule to granule injection frequencies less than 500 Hz. While the smaller granules were only successful in triggering ELMs approximately 20% of the time, the larger granules regularly demonstrated ELM triggering efficiencies of greater than 80%. A fast visible camera looking along the axis of injection observed the ablation of the lithium granules. We used the durationmore » of ablation as a benchmark for a neutral gas shielding calculation, and approximated the ablation rate and mass deposition location for the various size granules, using measured edge plasma profiles as inputs. In conclusion, this calculation suggests that the low triggering efficiency of the smaller granules is due to the inability of these granules to traverse the steep edge pressure gradient region and reach the top of the pedestal prior to full ablation.« less

Extravasation of contrast medium during CT examination: an observational case-control study.

PubMed

Alami, Zayneb; Nasri, Siham; Ahid, Samir; Kacem, Hanane Hadj

2015-01-01

Extravasation is an adverse reaction to intravenous injection of contrast medium (CM) during CT examination. The objectives of this study are to determine the frequency, management and outcomes of extravasations and to assess risk factors for extravasation. Every incident of extravasation which occurred between March 2012 and March 31, 2013 was recorded in an extravasation form. Ethics Committee approval was obtained and the patients gave their consent to participate in the study. Data collected in the form included patients' age, sex, comorbidities, symptoms, CM used, injection mode, site and rate, extravasated volume, location of extravasation, severity of injury, treatment and patient outcome. Each case was matched with 4 controls of the same age ± 5 years and the same gender when possible. Extravasation occurred in 18 (7 women, 11 men) out of 2,000 injections of CM (0.9%) with a median age of 53 (10-78) years. Automated injection was performed in all cases with a mean rate of 1.7 ml/s. Large extravasated volumes (≥50 ml) were more observed in patients undergoing CT angiography (28.6% vs. 6.6%, although not significant P=0.112). Multivariate analysis revealed a significant association between patients with cardiac diseases and extravasation (OR: 7.3, 95% CI (1.09-49.05), P=0.04) whereas the injection rate is a protective factor from extravasation (P=0.002). Extravasation of CM results in mild to moderate adverse effects in all cases. Our study suggests that patients with cardiac disease are more predisposed to contrast extravasation than others. Further and larger studies are needed to confirm this trend.

Transionospheric Propagation of VLF Transmitter Signals

NASA Astrophysics Data System (ADS)

Cohen, M.; Inan, U. S.; Lehtinen, N. G.

2012-12-01

Ground based Very Low Frequency (VLF, 3-30 kHz) radio transmitters may play a significant role in precipitation of inner belt (L<2.5) energetic Van Allen electrons. Initial analyses of the total contribution of VLF transmitters utilized models of transionospheric propagation, but some recent studies have suggested that those models may overestimate (by 20-100 dB) the VLF energy reaching the magnetosphere. One possible cause of this discrepancy was suggested to be conversion of wave energy into electrostatic modes in the D, E, and F regions, from ionospheric density irregularities, either natural or generated by the transmitter heating itself. The DEMETER satellite built a six year history of continuous and global survey mode data which, when combined, yields detailed pictures of the radiation pattern from many transmitters into space at 680 km, with 25 km resolution, and clear features like the interference pattern on the ground mapped upwards. With both E and B survey mode data, we can also directly approximate the total power injected into the magnetosphere from each transmitter, separately for day and night, as well as the power arriving at the conjugate region. We find no detectable variation of signal intensity with geomagnetic conditions. We find evidence of transmitter heating affecting the transionospheric propagation of other transmitters. We find that the power reaching the conjugate region is a large fraction of the power injected above the transmitter. We then employ a full wave model to simulate VLF transmitter transionospheric propagation, calculating the electromagnetic fields and power flux injected into the magnetosphere. Although the model does not include ionospheric irregularities, the radiation pattern largely matches the observed one, and the total power calculated is within 6 dB of observations for every transmitter, both day and night, and across a range of low to middle latitudes and transmitter powers. We thus conclude that the effect of ionospheric irregularities on VLF wave injection into the radiation belts may be small, if present at all.The nighttime radiation pattern of NWC at 700 km altitude, derived by averaging 6 years of DEMETER survey mode data.

HIV and HCV coinfection: prevalence, associated factors and genotype characterization in the Midwest Region of Brazil.

PubMed

Freitas, Solange Zacalusni; Teles, Sheila Araújo; Lorenzo, Paulo Cesar; Puga, Marco Antonio Moreira; Tanaka, Tayana Serpa Ortiz; Thomaz, Danilo Yamamoto; Martins, Regina Maria Bringel; Druzian, Angelita Fernandes; Lindenberg, Andréa Siqueira Campos; Torres, Marina Sawada; Pereira, Sérgio A; Villar, Livia Melo; Lampe, Elisabete; Motta-Castro, Ana Rita Coimbra

2014-01-01

A cross-sectional study on prevalence, associated factors and genotype distribution of HCV infection was conducted among 848 HIV-infected patients recruited at reference centers in the Midwest Region of Brazil. The prevalence rate of HIV-HCV coinfection was 6.9% (95% CI: 5.2 to 8.6). In multivariable analysis, increasing age, use of illicit drugs (injection and non-injection), a history of blood transfusion before 1994, and the absence of a steady partnership were significant independent associated factors for HIV-HCV coinfection. The phylogenetic analysis based on the NS5B region revealed the presence of two major circulating genotypes of HCV: genotypes 1 (58.3%) and 3 (41.7%). The prevalence of HIV-HCV coinfection was lower than those reported in studies conducted with HIV-infected patients in different regions of Brazil, due to the fact that illicit drug use is not a frequent mode of HIV transmission in this region of Brazil. Serologic screening of HIV-patients for HCV before initiating antiretroviral treatment, a comprehensive identification of associated factors, and the implementation of effective harm reduction programs are highly recommended to provide useful information for treatment and to prevent HCV coinfection in these patients.

Lower Hybrid Wave Induced Rotation on Alcator C-Mod

NASA Astrophysics Data System (ADS)

Parker, Ron; Podpaly, Yuri; Rice, John; Schmidt, Andrea

2009-11-01

Injection of RF power in the vicinity of the lower hybrid frequency has been observed to cause strong counter current rotation in Alcator C-Mod plasmas [1,2]. The spin-up rate is consistent with the rate at which momentum is injected by the LH waves, and also the rate at which fast electron momentum is transferred to the ions. A momentum diffusivity of ˜ 0.1 m^2/s is sufficient to account for the observed steady-state rotation. This value is also comparable with that derived from an analysis of rotation induced by RF mode conversion [3]. Radial force balance requires a radial electric field, suggesting a buildup of negative charge in the plasma core. This may be the result of an inward pinch of the LH produced fast electrons, as would be expected for resonant trapped particles. Analysis of the fast-electron-produced bremsstrahlung during LH power modulation experiments yields an inward pinch velocity of ˜ 1 m/s, consistent with the estimated trapped particle pinch velocity. [4pt] [1] A. Ince-Cushman, et.al., Phys. Rev. Lett., 102, 035002 (2009)[0pt] [2] J. E. Rice, et. al., Nucl. Fusion 49, 025004 (2009)[0pt] [3] Y. Lin, et.al., this meeting

Microfluidic Flow Injection Analysis with Thermal Lens Microscopic Detection for Determination of NGAL

NASA Astrophysics Data System (ADS)

Radovanović, Tatjana; Liu, Mingqiang; Likar, Polona; Klemenc, Matjaž; Franko, Mladen

2015-06-01

A combined microfluidic flow injection analysis-thermal lens microscopy (FIA-TLM) system was applied for determination of neutrophil gelatinase-associated lipocalin (NGAL)—a biomarker of acute kidney injury. NGAL was determined following a commercial ELISA assay and transfer of the resulting solution into the FIA-TLM system with a 100 m deep microchannel. At an excitation power of 100 mW, the FIA-TLM provided about seven times lower limits of detection (1.5 pg as compared to a conventional ELISA test, and a sample throughput of six samples per minute, which compares favorably with sample throughput of the microtiter plate reader, which reads 96 wells in about 30 min. Comparison of results for NGAL in plasma samples from healthy individuals and for NGAL dynamics in patients undergoing coronary angiography measured with transmission mode spectrometry on a microtiter plate reader and with FIA-TLM showed good agreement. In addition to improved LOD, the high sensitivity of FIA-TLM offers possibilities of a further reduction of the total reaction time of the NGAL ELISA test by sacrificing some of the sensitivity while reducing the duration of individual incubation steps.

Effects of Mean Flow Profiles on Instability of a Low-Density Gas Jet Injected into a High-Density Gas

NASA Technical Reports Server (NTRS)

Vedantam, Nanda Kishore

2003-01-01

The objective of this study was to investigate the effects of the mean flow profiles on the instability characteristics in the near-injector region of low-density gas jets injected into high-density ambient gas mediums. To achieve this, a linear temporal stability analysis and a spatio-temporal stability analysis of a low-density round gas jet injected vertically upwards into a high-density ambient gas were performed by assuming three different sets of mean velocity and density profiles. The flow was assumed to be isothermal and locally parallel. Viscous and diffusive effects were ignored. The mean flow parameters were represented as the sum of the mean value and a small normal-mode fluctuation. A second order differential equation governing the pressure disturbance amplitude was derived from the basic conservation equations. The first set of mean velocity and density profiles assumed were those used by Monkewitz and Sohn for investigating absolute instability in hot jets. The second set of velocity and density profiles assumed for this study were the ones used by Lawson. And the third set of mean profiles included a parabolic velocity profile and a hyperbolic tangent density profile. The effects of the inhomogeneous shear layer and the Froude number (signifying the effects of gravity) on the temporal and spatio-temporal results for each set of mean profiles were delineated. Additional information is included in the original extended abstract.

[Patterns of action potential firing in cortical neurons of neonatal mice and their electrophysiological property].

PubMed

Furong, Liu; Shengtian, L I

2016-05-25

To investigate patterns of action potential firing in cortical heurons of neonatal mice and their electrophysiological properties. The passive and active membrane properties of cortical neurons from 3-d neonatal mice were observed by whole-cell patch clamp with different voltage and current mode. Three patterns of action potential firing were identified in response to depolarized current injection. The effects of action potential firing patterns on voltage-dependent inward and outward current were found. Neurons with three different firing patterns had different thresholds of depolarized current. In the morphology analysis of action potential, the three type neurons were different in rise time, duration, amplitude and threshold of the first action potential evoked by 80 pA current injection. The passive properties were similar in three patterns of action potential firing. These results indicate that newborn cortical neurons exhibit different patterns of action potential firing with different action potential parameters such as shape and threshold.

Properties of Alfven Eigenmodes in the TAE range on the National Spherical Torus Experiment-Upgrade

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

None

2013-04-24

A second Neutral Beam (NB) injection line is being installed on the NSTX Upgrade device, resulting in six NB sources with di erent tangency radii that will be available for heating and current drive. This work explores the properties of instabilities in the frequency range of the Toroidal Alfv en Eigenmode (TAE) for NSTX-U scenarios with various NB injection geometries, from more perpendicular to more tangential, and with increased toroidal magnetic eld with respect to previous NSTX scenarios. Predictions are based on analysis through the ideal MHD code NOVA-K. For the scenarios considered in this work, modi cations of themore » Alfv en continuum result in a frequency upshift and a broadening of the radial mode structure. The latter e ect may have consequences for fast ion transport and loss. Preliminary stability considerations indicate that TAEs are potentially unstable, with ion Landau damping representing the dominant damping mechanism« less

Determination of ammonium ion by fluorometry or spectrophotometry after on-line derivatization with o-phthalaldehyde

NASA Technical Reports Server (NTRS)

Goyal, S. S.; Rains, D. W.; Huffaker, R. C.

1988-01-01

A fast, sensitive, simple, and highly reproducible method for routine assay of ammonium ion (NH4+) was developed by using HPLC equipment. The method is based on the reaction of NH4+ with o-phthalaldehyde (OPA) in the presence of 2-mercaptoethanol. After an on-line derivatization, the resulting NH4(+)-OPA product was quantified by using fluorometric or spectrophotometric detection. For fluorometric detection, the excitation and emission wavelengths were 410 and 470 nm, respectively. The spectrophotometric detection was made by measuring absorbance at 410 nm. Results on the effects of OPA-reagent composition and pH, reaction temperature, sample matrix, and linearity of the assay are presented. Even though it took about 2 min from the time of sample injection to the appearance of sample peak, sample injections could be overlapped at an interval of about 1 min. Thus, the actual time needed for analysis was about 1 min per assay. The method can be used in a fully automated mode by using an autosampler injector.

Predictions of the near edge transport shortfall in DIII-D L-mode plasmas using the trapped gyro-Landau-fluid model [Predictions of the near edge transport shortfall in DIII-D L-mode plasmas using the TGLF model

DOE PAGES

Kinsey, Jon E.; Staebler, Gary M.; Candy, Jefferey M.; ...

2015-01-14

Previous studies of DIII-D L-mode plasmas have shown that a transport shortfall exists in that our current models of turbulent transport can significantly underestimate the energy transport in the near edge region. In this paper, the Trapped Gyro-Landau-Fluid (TGLF) drift wave transport model is used to simulate the near edge transport in a DIII-D L-mode experiment designed to explore the impact of varying the safety factor on the shortfall. We find that the shortfall systematically increases with increasing safety factor and is more pronounced for the electrons than for the ions. Within the shortfall dataset, a single high current casemore » has been found where no transport shortfall is predicted. Reduced neutral beam injection power has been identified as the key parameter separating this discharge from other discharges exhibiting a shortfall. Further analysis shows that the energy transport in the L-mode near edge region is not stiff according to TGLF. Unlike the H-mode core region, the predicted temperature profiles are relatively more responsive to changes in auxiliary heating power. In testing the fidelity of TGLF for the near edge region, we find that a recalibration of the collision model is warranted. A recalibration improves agreement between TGLF and nonlinear gyrokinetic simulations performed using the GYRO code with electron-ion collisions. As a result, the recalibration only slightly impacts the predicted shortfall.« less

Preliminary results toward injection locking of an incoherent laser array

NASA Technical Reports Server (NTRS)

Daher, J.

1986-01-01

The preliminary results of phase locking an incoherent laser array to a master source in an attempt to achieve coherent operation are presented. The techniques necessary to demonstrate phase locking are described along with some topics for future consideration. As expected, the results obtained suggest that injection locking of an array, where the spacing between adjacent longitudinal modes of its elements is significantly larger than the locking bandwidth, may not be feasible.

50 Mb/s, 220-mW Laser-Array Transmitter

NASA Technical Reports Server (NTRS)

Cornwell, Donald M., Jr.

1992-01-01

Laser transmitter based on injection locking produces single-wavelength, diffraction-limited, single-lobe beam. Output stage is array of laser diodes producing non-diffraction-limited, multi-mode beam in absence of injection locking. Suitable for both free-space and optical-fiber communication systems. Because beam from transmitter focused to spot as small as 5 micrometers, devices usable for reading and writing optical disks at increased information densities. Application also in remote sensing and ranging.

Study of atmospheric plasma spray process with the emphasis on gas-shrouded nozzles

NASA Astrophysics Data System (ADS)

Jankovic, Miodrag M.

An atmospheric plasma spraying process is investigated in this work by using experimental approach and mathematical modelling. Emphasis was put on the gas shrouded nozzles, their design, and the protection against the mixing with the surrounding air, which they give to the plasma jet. First part of the thesis is dedicated to the analysis of enthalpy probe method, as a major diagnostic tool in this work. Systematic error in measuring the stagnation pressure, due to a big temperature difference between the plasma and the water-cooled probe, is investigated here. Parallel measurements with the enthalpy probe and an uncooled ceramic probe were performed. Also, numerical experiments were conducted, using the k-ɛ model of turbulence. Based on the obtained results, a compensating algorithm for the above error is suggested. Major objective of the thesis was to study the plasma spraying process, and potential benefits from using the gas shrouded nozzles. Mathematical modelling was used to perform the parametric study on the flow pattern inside these nozzles. Two nozzles were used: a commercial conical nozzle, and a custom-made curvilinear nozzle. The later is aimed towards elimination of the cold air entrainment, recorded for the conical nozzle. Also, parametric study on the shrouding gas and its interaction with the plasma jet was carried out. Two modes of the shrouding gas injection were tested: through sixteen injection ports, and through a continuous slot, surrounding the plasma jet. Both nozzles and both injection modes were thoroughly tested, experimentally and numerically. The curvilinear nozzle completely eliminates the cold air entrainment and yields significantly higher plasma temperature. Also, injection through the continuous slot resulted in a much better protection of the plasma jet. Both nozzles were used to perform the spraying tests. Obtained coatings were tested on porosity, adhesion strength, and micro- structure. These tests indicated better micro-structure of the coatings sprayed by the curvilinear nozzle. Also, their porosity was significantly lower, and the adhesion strength was higher for more than 25%. The overall results suggest that the curvilinear nozzles represent a much better solution for the gas shrouded plasma spraying.

Parametric effects on pinch-off modes in liquid/liquid jet systems

NASA Astrophysics Data System (ADS)

Milosevic, Ilija N.

Many industries rely on liquid/liquid extraction systems, where jet pinch off occurs on a regular basis. Inherent short time and length scales make analytical and numerical simulation of the process very challenging. A main objective of this work was to document the details of various pinch-off modes at different length scales using Laser Induced Fluorescence and Particle Image Velocimetry. A water glycerine mixture was injected into ambient either silicone oil or 1-octanol. The resultant viscosity ratios, inner to outer fluid, were 1.6 and 2.8, respectively. Ohnesorge numbers were 0.013 for ambient silicone oil and 0.08 for ambient 1-octanol. Reynolds and Strouhal numbers ranged from 30 to 100 and 0.5 to 3.5, respectively. Decreasing the Strouhal number increased the number of drops formed per forcing. Increasing the Reynolds number suppressed satellite formation, and in some cases the number of drops decreased from two to one per cycle. Increasing the Ohnesorge number to 0.08 suppressed the pinch off yielding a longer jet with three-dimensional threads. At Ohnesorge number 0.013, increasing the forcing amplitude shortened the jet, and eventually led to a dripping mode. High-resolution measurements of pinch-off angles were compared to results from similarity theory. Two modes were investigated: drops breaking from the jet (jet/drop) and, one drop splitting into two (splitting drop). The jet/drop mode angle measurements agreed with similarity predictions. The splitting drop mode converged towards smaller angles. Scaling analysis showed that a Stokesian similarity regime applied for a neck radius of 6 microns or less. The smallest radius observed in experiments was 15 microns. Therefore, it is not known whether splitting drop mode might still converge to same behavior.

Instability Analysis of a Low-Density Gas Jet Injected into a High-Density Gas

NASA Technical Reports Server (NTRS)

Lawson, Anthony Layiwola

2001-01-01

The objective of this study was to determine the effects of buoyancy on the absolute instability of low-density gas jets injected into high-density gas mediums. Most of the existing analyses of low-density gas jets injected into a high-density ambient have been carried out neglecting effects of gravity. In order to investigate the influence of gravity on the near-injector development of the flow, a linear temporal stability analysis and a spatio-temporal stability analysis of a low-density round jet injected into a high-density ambient gas were performed. The flow was assumed to be isothermal and locally parallel; viscous and diffusive effects were ignored. The variables were represented as the sum of the mean value and a normal-mode small disturbance. An ordinary differential equation governing the amplitude of the pressure disturbance was derived. The velocity and density profiles in the shear layer, and the Froude number (signifying the effects of gravity) were the three important parameters in this equation. Together with the boundary conditions, an eigenvalue problem was formulated. Assuming that the velocity and density profiles in the shear layer to be represented by hyperbolic tangent functions, the eigenvalue problem was solved for various values of Froude number. The temporal growth rates and the phase velocity of the disturbances were obtained. It was found that the presence of variable density within the shear layer resulted in an increase in the temporal amplification rate of the disturbances and an increase in the range of unstable frequencies, accompanied by a reduction in the phase velocities of the disturbances. Also, the temporal growth rates of the disturbances were increased as the Froude number was reduced (i.e. gravitational effects increased), indicating the destabilizing role played by gravity. The spatio-temporal stability analysis was performed to determine the nature of the absolute instability of the jet. The roles of the density ratio, Froude number, Schmidt number, and the lateral shift between the density and velocity profiles on the jet s absolute instability were determined. Comparisons of the results with previous experimental studies show good agreement when the effects of these variables are combined together. Thus, the combination of these variables determines how absolutely unstable the jet will be. Experiments were carried out to observe the qualitative differences between a round low-density gas jet injected into a high-density gas (helium jet injected into air) and a round constant density jet (air jet injected into air). Flow visualizations and velocity measurements in the near-injector region of the helium jet show more mixing and spreading of the helium jet than the air jet. The vortex structures develop and contribute to the jet spreading causing the helium jet to oscillate.

Laser frequency multiplication

NASA Astrophysics Data System (ADS)

1991-11-01

A high quality mode locked pulse train was obtained at 9.55 microns, the CO2 wavelength chosen for frequency doubling into the atmospheric window at 4.8 microns. The pulse train consists of a 3 micro sec burst of 1.5 nsec pulses separated by 40 nsec, in a TEM (sub 00) mode and with a total energy of 100 mJ. The pulse intensity without focussing is about 3 MW/sq.cm., already quite close to the target intensity of 10 MW/sq.cm. for frequency doubling in a AgGaSe2 crystal. The mode-locked train is obtained by intracavity modulation at 12.5 MHz using a germanium crystal driven with a power of about 30 Watts. Line selection is achieved firstly by the use of a 0.92 mm thick CaF2 plate at the Brewster angle within the cavity, which completely suppresses 10.6 micron band radiation. Secondly, a particular rotational line, the P20 at 9.55 micron, is selected by the injection of a continuous beam is mode-matched to the pulsed laser cavity using a long focal length lens, and for best line-locking it is necessary to fine tune the length of the pulsed laser resonator. Injection causes substantial depression of the gain switched spike.

An assessment of the current treatment landscape for rheumatology patients in Qatar: Recognising unmet needs and moving towards solutions.

PubMed

Emadi, Samar Al; Hammoudeh, Mohammed; Mounir, Mohamed; Mueller, Ruediger B; Wells, Alvin F; Sarakbi, Housam Aldeen

2017-04-01

Objective This study assessed the mode of application (oral, intravenous or subcutaneous (SC)) currently employed in the treatment of rheumatoid arthritis (RA) in patients from Qatar in comparison with patients' individual preferences for the mode of application of their treatment. Methods This study included 294 RA patients visiting three clinics at the main referral hospital in Qatar who were interviewed using a standard questionnaire to determine their preference of mode of application for their disease-modifying antirheumatic drug (DMARD) treatment in relation to their currently employed mode of application. Results The majority of patients were female (76%), and 93% of male patients and 61% of female patients in the study clinics were of a nationality other than Qatari. The highest patient preference recorded was for an oral therapy (69%), compared with injection (23%) and intravenous (8%) therapy. In total, 85% of patients expressed a preference to remain on oral therapy compared with 63% and 58% of intravenous and SC injection patients indicating a preference to remain on their current method of administration. Conclusions This high preference for oral therapies highlights the considerable need for incorporation of new oral targeted synthetic DMARD therapies into clinical practice within the region.

An assessment of the current treatment landscape for rheumatology patients in Qatar: Recognising unmet needs and moving towards solutions

PubMed Central

Hammoudeh, Mohammed; Mounir, Mohamed; Mueller, Ruediger B.; Wells, Alvin F.; Sarakbi, Housam Aldeen

2017-01-01

Objective This study assessed the mode of application (oral, intravenous or subcutaneous (SC)) currently employed in the treatment of rheumatoid arthritis (RA) in patients from Qatar in comparison with patients’ individual preferences for the mode of application of their treatment. Methods This study included 294 RA patients visiting three clinics at the main referral hospital in Qatar who were interviewed using a standard questionnaire to determine their preference of mode of application for their disease-modifying antirheumatic drug (DMARD) treatment in relation to their currently employed mode of application. Results The majority of patients were female (76%), and 93% of male patients and 61% of female patients in the study clinics were of a nationality other than Qatari. The highest patient preference recorded was for an oral therapy (69%), compared with injection (23%) and intravenous (8%) therapy. In total, 85% of patients expressed a preference to remain on oral therapy compared with 63% and 58% of intravenous and SC injection patients indicating a preference to remain on their current method of administration. Conclusions This high preference for oral therapies highlights the considerable need for incorporation of new oral targeted synthetic DMARD therapies into clinical practice within the region. PMID:28415924

Wide-band fanned-out supercontinuum source covering O-, E-, S-, C-, L- and U-bands

NASA Astrophysics Data System (ADS)

Ahmad, H.; Latif, A. A.; Awang, N. A.; Zulkifli, M. Z.; Thambiratnam, K.; Ghani, Z. A.; Harun, S. W.

2012-10-01

A wide-band supercontinuum source generated by mode-locked pulses injected into a Highly Non-Linear Fiber (HNLF) is proposed and demonstrated. A 49 cm long Bismuth-Erbium Doped Fiber (Bi-EDF) pumped by two 1480 nm laser diodes acts as the active gain medium for a ring fiber laser, from which mode-locked pulses are obtained using the Non-Polarization Rotation (NPR) technique. The mode-locked pulses are then injected into a 100 m long HLNF with a dispersion of 0.15 ps/nm km at 1550 nm to generate a supercontinuum spectrum spanning from 1340 nm to more than 1680 nm with a pulse width of 0.08 ps and an average power of -17 dBm. The supercontinuum spectrum is sliced using a 24 channel Arrayed Waveguide Grating (AWG) with a channel spacing of 100 GHz to obtain a fanned-out laser output covering the O-, E-, S-, C-, L- and U-bands. The lasing wavelengths obtained have an average pulse width of 9 ps with only minor fluctuations and a mode-locked repetition rate of 40 MHz, and is sufficiently stable to be used in a variety of sensing and communication applications, most notably as cost-effective sources for Fiber-to-the-Home (FTTH) networks.

A selective and sensitive method for quantitation of lysergic acid diethylamide (LSD) in whole blood by gas chromatography-ion trap tandem mass spectrometry.

PubMed

Libong, Danielle; Bouchonnet, Stéphane; Ricordel, Ivan

2003-01-01

A gas chromatography-ion trap tandem mass spectrometry (GC-ion trap MS-MS) method for detection and quantitation of LSD in whole blood is presented. The sample preparation process, including a solid-phase extraction step with Bond Elut cartridges, was performed with 2 mL of whole blood. Eight microliters of the purified extract was injected with a cold on-column injection method. Positive chemical ionization was performed using acetonitrile as reagent gas; LSD was detected in the MS-MS mode. The chromatograms obtained from blood extracts showed the great selectivity of the method. GC-MS quantitation was performed using lysergic acid methylpropylamide as the internal standard. The response of the MS was linear for concentrations ranging from 0.02 ng/mL (detection threshold) to 10.0 ng/mL. Several parameters such as the choice of the capillary column, the choice of the internal standard and that of the ionization mode (positive CI vs. EI) were rationalized. Decomposition pathways under both ionization modes were studied. Within-day and between-day stability were evaluated.

Edge localized mode characteristics during edge localized mode mitigation by supersonic molecular beam injection in Korea Superconducting Tokamak Advanced Research

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

Lee, H. Y.; Hong, J. H.; Jang, J. H.

It has been reported that supersonic molecular beam injection (SMBI) is an effective means of edge localized mode (ELM) mitigation. This paper newly reports the changes in the ELM, plasma profiles, and fluctuation characteristics during ELM mitigation by SMBI in Korea Superconducting Tokamak Advanced Research. During the mitigated ELM phase, the ELM frequency increased by a factor of 2–3 and the ELM size, which was estimated from the D{sub α} amplitude, the fractional changes in the plasma-stored energy and the line-averaged electron density, and divertor heat flux during an ELM burst, decreased by a factor of 0.34–0.43. Reductions in themore » electron and ion temperatures rather than in the electron density were observed during the mitigated ELM phase. In the natural ELM phase, frequency chirping of the plasma fluctuations was observed before the ELM bursts; however, the ELM bursts occurred without changes in the plasma fluctuation frequency in the mitigated ELM phase.« less

Simulation of multi-pulse coaxial helicity injection in the Sustained Spheromak Physics Experiment

NASA Astrophysics Data System (ADS)

O'Bryan, J. B.; Romero-Talamás, C. A.; Woodruff, S.

2018-03-01

Nonlinear, numerical computation with the NIMROD code is used to explore magnetic self-organization during multi-pulse coaxial helicity injection in the Sustained Spheromak Physics eXperiment. We describe multiple distinct phases of spheromak evolution, starting from vacuum magnetic fields and the formation of the initial magnetic flux bubble through multiple refluxing pulses and the eventual onset of the column mode instability. Experimental and computational magnetic diagnostics agree on the onset of the column mode instability, which first occurs during the second refluxing pulse of the simulated discharge. Our computations also reproduce the injector voltage traces, despite only specifying the injector current and not explicitly modeling the external capacitor bank circuit. The computations demonstrate that global magnetic evolution is fairly robust to different transport models and, therefore, that a single fluid-temperature model is sufficient for a broader, qualitative assessment of spheromak performance. Although discharges with similar traces of normalized injector current produce similar global spheromak evolution, details of the current distribution during the column mode instability impact the relative degree of poloidal flux amplification and magnetic helicity content.

Reactive Tracer Techniques to Quantitatively Monitor Carbon Dioxide Storage in Geologic Formations

NASA Astrophysics Data System (ADS)

Matter, J. M.; Carson, C.; Stute, M.; Broecker, W. S.

2012-12-01

Injection of CO2 into geologic storage reservoirs induces fluid-rock reactions that may lead to the mineralization of the injected CO2. The long-term safety of geologic CO2 storage is, therefore, determined by in situ CO2-fluid-rock reactions. Currently existing monitoring and verification techniques for CO2 storage are insufficient to characterize the solubility and reactivity of the injected CO2, and to establish a mass balance of the stored CO2. Dissolved and chemically transformed CO2 thus avoid detection. We developed and are testing a new reactive tracer technique for quantitative monitoring and detection of dissolved and chemically transformed CO2 in geologic storage reservoirs. The technique involves tagging the injected carbon with radiocarbon (14C). Carbon-14 is a naturally occurring radioisotope produced by cosmic radiation and made artificially by 14N neutron capture. The ambient concentration is very low with a 14C/12C ratio of 10-12. The concentration of 14C in deep geologic formations and fossil fuels is at least two orders of magnitude lower. This makes 14C an ideal quantitative tracer for tagging underground injections of anthropogenic CO2. We are testing the feasibility of this tracer technique at the CarbFix pilot injection site in Iceland, where approximately 2,000 tons of CO2 dissolved in water are currently injected into a deep basalt aquifer. The injected CO2 is tagged with 14C by dynamically adding calibrated amounts of H14CO3 solution to the injection stream. The target concentration is 12 Bq/kg of injected water, which results in a 14C activity that is 5 times enriched compared to the 1850 background. In addition to 14C as a reactive tracer, trifluormethylsulphur pentafluoride (SF5CF3) and sulfurhexafluoride (SF6) are used as conservative tracers to monitor the transport of the injected CO2 in the subsurface. Fluid samples are collected for tracer analysis from the injection and monitoring wells on a regular basis. Results show a fast reaction of the injected CO2 with the ambient reservoir fluid and rocks. Mixing and in situ CO2-water-rock reactions are detected by changes in the different tracer ratios. The feasibility of 14C as a reactive tracer for geologic CO2 storage also depends on the analytical technique used to measure 14C activities. Currently, 14C is analyzed using Accelerator Mass Spectrometery (AMS), which is expensive and requires centralized facilities. To enable real time online monitoring and verification, we are developing an alternative detection method for radiocarbon. The IntraCavity OptoGalvanic Spectroscopy (ICOGS) system is using a CO2 laser to detect carbon isotope ratios at environmental levels. Results from our prototype of this bench-top technology demonstrate that an ICOGS system can be used in a continuous mode with analysis times of the order of minutes, and can deliver data of similar quality as AMS.

Numerical Investigation of Dual-Mode Scramjet Combustor with Large Upstream Interaction

NASA Technical Reports Server (NTRS)

Mohieldin, T. O.; Tiwari, S. N.; Reubush, David E. (Technical Monitor)

2004-01-01

Dual-mode scramjet combustor configuration with significant upstream interaction is investigated numerically, The possibility of scaling the domain to accelerate the convergence and reduce the computational time is explored. The supersonic combustor configuration was selected to provide an understanding of key features of upstream interaction and to identify physical and numerical issues relating to modeling of dual-mode configurations. The numerical analysis was performed with vitiated air at freestream Math number of 2.5 using hydrogen as the sonic injectant. Results are presented for two-dimensional models and a three-dimensional jet-to-jet symmetric geometry. Comparisons are made with experimental results. Two-dimensional and three-dimensional results show substantial oblique shock train reaching upstream of the fuel injectors. Flow characteristics slow numerical convergence, while the upstream interaction slowly increases with further iterations. As the flow field develops, the symmetric assumption breaks down. A large separation zone develops and extends further upstream of the step. This asymmetric flow structure is not seen in the experimental data. Results obtained using a sub-scale domain (both two-dimensional and three-dimensional) qualitatively recover the flow physics obtained from full-scale simulations. All results show that numerical modeling using a scaled geometry provides good agreement with full-scale numerical results and experimental results for this configuration. This study supports the argument that numerical scaling is useful in simulating dual-mode scramjet combustor flowfields and could provide an excellent convergence acceleration technique for dual-mode simulations.

Perturbative studies of toroidal momentum transport in KSTAR H-mode and the effect of ion temperature perturbation

NASA Astrophysics Data System (ADS)

Yang, S. M.; Na, Yong-Su; Na, D. H.; Park, J.-K.; Shi, Y. J.; Ko, W. H.; Lee, S. G.; Hahm, T. S.

2018-06-01

Perturbative experiments have been carried out using tangential neutral beam injection (NBI) and non-resonant magnetic perturbation (NRMP) to analyze the momentum transport properties in KSTAR H-modes. Diffusive and non-diffusive terms of momentum transport are evaluated from the transient analysis. Although the operating conditions and methodologies applied in the two cases are similar, the momentum transport properties obtained show clear differences. The estimated momentum diffusivity and pinch obtained in the NBI modulation experiments is larger than that in the NRMP modulation experiments. We found that this discrepancy could be a result of uncertainties in the assumption for the analysis. By introducing time varying momentum transport coefficients depending on the temperature gradient, the linearized equation shows that if the temperature perturbation exists, the evolution of toroidal rotation perturbation could be faster than the transport rate of mean quantity, since the evolution of toroidal rotation perturbation is related to , a momentum diffusivity from perturbative analysis. This could explain the estimated higher momentum diffusivity using time independent transport coefficients in NBI experiments with higher ion temperature perturbation compared to that in NRMP modulation experiments. The differences in the momentum transport coefficient with NRMP and NBI are much reduced by considering time varying momentum transport coefficients in the time dependent transport simulation.

Stimulation of plasma waves by electron guns on the ISEE-1 satellite

NASA Technical Reports Server (NTRS)

Lebreton, J.-P.; Torbert, R.; Anderson, R.; Harvey, C.

1982-01-01

The results of the ISEE-1 satellite experiment relating to observations of the waves stimulated during electron injections, when the spacecraft is passing through the magnetosphere, the magnetosheath, and the solar wind, are discussed. It is shown that the injection of an electron beam current of the order of 10 to 60 microamperes with energies ranging from 0 to 40 eV produces enhancements in the electric wave spectrum. An attempt has been made to identify the low-frequency electrostatic wave observed below the ion plasma frequency as an ion acoustic mode, although the excitation mechanism is not clear. A coupling mechanism between the electron plasma mode and streaming electrons with energies higher than the thermal speed of the cold electron population has been proposed to explain the observations above the electron plasma frequency.

FAST TRACK COMMUNICATION Generation of stable multi-jets by flow-limited field-injection electrostatic spraying and their control via I-V characteristics

NASA Astrophysics Data System (ADS)

Gu, W.; Heil, P. E.; Choi, H.; Kim, K.

2010-12-01

The I-V characteristics of flow-limited field-injection electrostatic spraying (FFESS) were investigated, exposing a new way to predict and control the specific spraying modes from single-jet to multi-jet. Monitoring the I-V characteristics revealed characteristic drops in the current upon formation of an additional jet in the multi-jet spraying mode. For fixed jet numbers, space-charge-limited current behaviour was measured which was attributed to space charge in the dielectric liquids between the needle electrode and the nozzle opening. The present work establishes that FFESS can, in particular, generate stable multiple jets and that their control is possible through monitoring the I-V characteristics. This can allow for automatic control of the FFESS process and expedite its future scientific and industrial applications.

High-Throughput Analysis of Methylmalonic Acid in Serum, Plasma, and Urine by LC-MS/MS. Method for Analyzing Isomers Without Chromatographic Separation.

PubMed

Kushnir, Mark M; Nelson, Gordon J; Frank, Elizabeth L; Rockwood, Alan L

2016-01-01

Measurement of methylmalonic acid (MMA) plays an important role in the diagnosis of vitamin B12 deficiency. Vitamin B12 is an essential cofactor for the enzymatic carbon rearrangement of methylmalonyl-CoA (MMA-CoA) to succinyl-CoA (SA-CoA), and the lack of vitamin B12 leads to elevated concentrations of MMA. Presence of succinic acid (SA) complicates the analysis because mass spectra of MMA and SA are indistinguishable, when analyzed in negative ion mode and the peaks are difficult to resolve chromatographically. We developed a method for the selective analysis of MMA that exploits the significant difference in fragmentation patterns of di-butyl derivatives of the isomers MMA and SA in a tandem mass spectrometer when analyzed in positive ion mode. Tandem mass spectra of di-butyl derivatives of MMA and SA are very distinct; this allows selective analysis of MMA in the presence of SA. The instrumental analysis is performed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) in positive ion mode, which is, in combination with selective extraction of acidic compounds, is highly selective for organic acids with multiple carboxyl groups (dicarboxylic, tricarboxylic, etc.). In this method organic acids with a single carboxyl group are virtually undetectable in the mass spectrometer; the only organic acid, other than MMA, that is detected by this method is its isomer, SA. Quantitative measurement of MMA in this method is performed using a deconvolution algorithm, which mathematically resolves the signal corresponding to MMA and does not require chromatographic resolution of the MMA and SA peaks. Because of its high selectivity, the method utilizes isocratic chromatographic separation; reconditioning and re-equilibration of the chromatographic column between injections is unnecessary. The above features of the method allow high-throughput analysis of MMA with analysis cycle time of 1 min.

An automated water iodinating subsystem for manned space flight

NASA Technical Reports Server (NTRS)

Houck, O. K.; Wynveen, R. A.

1974-01-01

Controlling microbial growth by injecting iodine (l2) into water supplies is a widely acceptable technique, but requires a specialized injection method for space flight. An electrochemical l2 injection method and l2 level monitor are discussed in this paper, which also describe iodination practices previously used in the manned space program and major l2 biocidal characteristics. The development and design of the injector and monitor are described, and results of subsequent experiments are presented. Also presented are expected vehicle penalties for utilizing the l2 injector in certain space missions, especially the Space Shuttle, and possible injector failure modes and their criticality.

Direct link of a mid-infrared QCL to a frequency comb by optical injection.

PubMed

Borri, S; Galli, I; Cappelli, F; Bismuto, A; Bartalini, S; Cancio, P; Giusfredi, G; Mazzotti, D; Faist, J; De Natale, P

2012-03-15

A narrow-linewidth comb-linked nonlinear source is used as master radiation to injection lock a room-temperature mid-infrared quantum cascade laser (QCL). This process leads to a direct lock of the QCL to the optical frequency comb, providing the unique features of narrow linewidth, absolute frequency, higher output power, and wide mode-hop-free tunability. The QCL reproduces the injected radiation within more than 94%, with a reduction of the frequency-noise spectral density by 3 to 4 orders of magnitude up to about 100 kHz, and a linewidth narrowing from a few MHz to 20 kHz.

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

Solomon, W. M.; Snyder, P. B.; Bortolon, A.

In a new high pedestal regime ("Super H-mode") we predicted and accessed DIII-D. Super H-mode was first achieved on DIII-D using a quiescent H-mode edge, enabling a smooth trajectory through pedestal parameter space. By exploiting Super H-mode, it has been possible to access high pedestal pressures at high normalized densities. And while elimination of Edge localized modes (ELMs) is beneficial for Super H-mode, it may not be a requirement, as recent experiments have maintained high pedestals with ELMs triggered by lithium granule injection. Simulations using TGLF for core transport and the EPED model for the pedestal find that ITER canmore » benefit from the improved performance associated with Super H-mode, with increased values of fusion power and gain possible. In similar studies demonstrate that the Super H-mode pedestal can be advantageous for a steady-state power plant, by providing a path to increasing the bootstrap current while simultaneously reducing the demands on the core physics performance.« less

Tailoring Meridional and Seasonal Radiative Forcing by Sulfate Aerosol Solar Geoengineering

NASA Astrophysics Data System (ADS)

Dai, Z.; Weisenstein, D. K.; Keith, D. W.

2018-01-01

We study the possibility of designing solar radiation management schemes to achieve a desired meridional radiative forcing (RF) profile using a two-dimensional chemistry-transport-aerosol model. Varying SO2 or H2SO4 injection latitude, altitude, and season, we compute RF response functions for a broad range of possible injection schemes, finding that linear combinations of these injection cases can roughly achieve RF profiles that have been proposed to accomplish various climate objectives. Globally averaged RF normalized by the sulfur injection rate (the radiative efficacy) is largest for injections at high altitudes, near the equator, and using emission of H2SO4 vapor into an aircraft wake to produce accumulation-mode particles. There is a trade-off between radiative efficacy and control as temporal and spatial control is best achieved with injections at lower altitudes and higher latitudes. These results may inform studies using more realistic models that couple aerosol microphysics, chemistry, and stratospheric dynamics.

Pseudorandom binary injection of levitons for electron quantum optics

NASA Astrophysics Data System (ADS)

Glattli, D. C.; Roulleau, P.

2018-03-01

The recent realization of single-electron sources lets us envision performing electron quantum optics experiments, where electrons can be viewed as flying qubits propagating in a ballistic conductor. To date, all electron sources operate in a periodic electron injection mode, leading to energy spectrum singularities in various physical observables which sometimes hide the bare nature of physical effects. To go beyond this, we propose a spread-spectrum approach where electron flying qubits are injected in a nonperiodic manner following a pseudorandom binary bit pattern. Extending the Floquet scattering theory approach from periodic to spread-spectrum drive, the shot noise of pseudorandom binary sequences of single-electron injection can be calculated for leviton and nonleviton sources. Our new approach allows us to disentangle the physics of the manipulated excitations from that of the injection protocol. In particular, the spread-spectrum approach is shown to provide better knowledge of electronic Hong-Ou-Mandel correlations and to clarify the nature of the pulse train coherence and the role of the dynamical orthogonality catastrophe for noninteger charge injection.

DLTS Analysis and Interface Engineering of Solution Route Fabricated Zirconia Based MIS Devices Using Plasma Treatment

NASA Astrophysics Data System (ADS)

Kumar, Arvind; Mondal, Sandip; Koteswara Rao, K. S. R.

2018-02-01

In this work, we have fabricated low-temperature sol-gel spin-coated and oxygen (O2) plasma treated ZrO2 thin film-based metal-insulator-semiconductor devices. To understand the impact of plasma treatment on the Si/ZrO2 interface, deep level transient spectroscopy measurements were performed. It is reported that the interface state density ( D it) comes down to 7.1 × 1010 eV-1 cm-2 from 4 × 1011 eV-1 cm-2, after plasma treatment. The reduction in D it is around five times and can be attributed to the passivation of oxygen vacancies near the Si/ZrO2 interface, as they try to relocate near the interface. The energy level position ( E T) of interfacial traps is estimated to be 0.36 eV below the conduction band edge. The untreated ZrO2 film displayed poor leakage behavior due to the presence of several traps within the film and at the interface; O2 plasma treated films show improved leakage current density as they have been reduced from 5.4 × 10-8 A/cm2 to 1.98 × 10-9 A/cm2 for gate injection mode and 6.4 × 10-8 A/cm2 to 6.3 × 10-10 A/cm2 for substrate injection mode at 1 V. Hence, we suggest that plasma treatment might be useful in future device fabrication technology.

Longitudinal mode selection in a delay-line homogeneously broadened oscillator with a fast saturable amplifier.

PubMed

Fleyer, Michael; Horowitz, Moshe

2017-05-01

Homogeneously broadened delay-line oscillators such as lasers or optoelectronic oscillators (OEOs) can potentially oscillate in a large number of cavity modes that are supported by their amplifier bandwidth. In a continuous wave operating mode, the oscillating mode is selected between one or few cavity modes that experience the highest small-signal gain. In this manuscript, we show that the oscillation mode of a homogeneously broadened oscillator can be selected from a large number of modes in a frequency region that can be broader than the full width at half maximum of the effective cavity filter. The mode is selected by a short-time injection of an external signal into the oscillator. After the external signal is turned off, the oscillation is maintained in the selected mode even if this mode has a significantly lower small-signal gain than that of other cavity modes. The stability of the oscillation is obtained due to nonlinear saturation effect in the oscillator amplifier. We demonstrate, experimentally and theoretically, mode selection in a long cavity OEO. We could select any desired mode between 400 cavity modes while maintaining ultra-low phase noise in the selected mode and in the non-oscillating modes. No mode-hopping was observed during our maximum measurement duration of about 24 hours.

Evaluation of perception of insulin therapy among Chinese patients with type 2 diabetes mellitus.

PubMed

Chen, C-C; Chang, M-P; Hsieh, M-H; Huang, C-Y; Liao, L-N; Li, T-C

2011-11-01

To evaluate whether perception of insulin therapy differs between patients with type 2 diabetes treated with insulin and those treated with oral hypoglycaemic agents (OHAs), and to examine whether gender, education level, injection duration and mode of injection were associated with the patients' perception of insulin therapy. The validated Chinese version of the Insulin Treatment Appraisal Scale (ITAS) was used to evaluate the perception of insulin therapy among 100 insulin-treated patients and 100 OHA-treated patients. The higher the total score, the more negative is the appraisal. The OHA-treated group had a higher mean total score (20 items), a higher mean total score for 16 negative items and a lower mean total score for four positive items than the insulin-treated group. The proportion of participants who rated the negative items as "agree" or "strongly agree" was significantly higher in the OHA-treated group than in the insulin-treated group. In addition, the proportion of participants who rated the four positive items as "agree" or "strongly agree" was lower in the OHA-treated group than in the insulin-treated group. Gender, education level, duration of insulin injection and mode of injection did not have a significant impact on perception of insulin therapy. Chinese type 2 diabetic patients taking OHAs had more negative beliefs and attitudes towards insulin therapy than patients being treated with insulin. This difference was not associated with either gender or education level. Furthermore, neither injection duration nor type of device was related to perception of insulin therapy. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

Rapid determination of tafenoquine in small volume human plasma samples by high-performance liquid chromatography-tandem mass spectrometry.

PubMed

Doyle, E; Fowles, S E; Summerfield, S; White, T J

2002-03-25

A method was developed for the determination of tafenoquine (I) in human plasma using high-performance liquid chromatography-tandem mass spectrometry. Prior to analysis, the protein in plasma samples was precipitated with methanol containing [2H3(15N)]tafenoquine (II) to act as an internal standard. The supernatant was injected onto a Genesis-C18 column without any further clean-up. The mass spectrometer was operated in the positive ion mode, employing a heat assisted nebulisation, electrospray interface. Ions were detected in multiple reaction monitoring mode. The assay required 50 microl of plasma and was precise and accurate within the range 2 to 500 ng/ml. The average within-run and between-run relative standard deviations were < 7% at 2 ng/ml and greater concentrations. The average accuracy of validation standards was generally within +/- 4% of the nominal concentration. There was no evidence of instability of I in human plasma following three complete freeze-thaw cycles and samples can safely be stored for at least 8 months at approximately -70 degrees C. The method was very robust and has been successfully applied to the analysis of clinical samples from patients and healthy volunteers dosed with I.

FDNS CFD Code Benchmark for RBCC Ejector Mode Operation: Continuing Toward Dual Rocket Effects

NASA Technical Reports Server (NTRS)

West, Jeff; Ruf, Joseph H.; Turner, James E. (Technical Monitor)

2000-01-01

Computational Fluid Dynamics (CFD) analysis results are compared with benchmark quality test data from the Propulsion Engineering Research Center's (PERC) Rocket Based Combined Cycle (RBCC) experiments to verify fluid dynamic code and application procedures. RBCC engine flowpath development will rely on CFD applications to capture the multi -dimensional fluid dynamic interactions and to quantify their effect on the RBCC system performance. Therefore, the accuracy of these CFD codes must be determined through detailed comparisons with test data. The PERC experiments build upon the well-known 1968 rocket-ejector experiments of Odegaard and Stroup by employing advanced optical and laser based diagnostics to evaluate mixing and secondary combustion. The Finite Difference Navier Stokes (FDNS) code [2] was used to model the fluid dynamics of the PERC RBCC ejector mode configuration. Analyses were performed for the Diffusion and Afterburning (DAB) test conditions at the 200-psia thruster operation point, Results with and without downstream fuel injection are presented.

Analytical and experimental performance of a dual-mode traveling wave tube and multistage depressed collector

NASA Technical Reports Server (NTRS)

Ramins, Peter; Force, Dale A.; Kosmahl, Henry G.

1987-01-01

A computational procedure for the design of traveling-wave-tube(TWT)/refocuser/multistage depressed collector (MDC) systems was used to design a short, permanent-magnet refocusing system and a highly efficient MDC for a medium-power, dual-mode, 4.8- to 9.6-GHz TWT. The computations were carried out with advanced, multidimensional computer programs which model the electron beam and follow the trajectories of representative charges from the radiofrequency (RF) input of the TWT, through the slow-wave structure and refocusing section, to their points of impact in the depressed collector. Secondary emission losses in the MDC were treated semiquantitatively by injecting representative secondary-electron-emission current into the MDA analysis at the point of impact of each primary beam. A comparison of computed and measured TWT and MDC performance showed very good agreement. The electrodes of the MDC were fabricated from a particluar form of isptropic graphite that was selected for its low secondary electron yield, ease of machinability, and vacuum properties.

Dynamics of a grain-filled ball on a vibrating plate.

PubMed

Pacheco-Vázquez, F; Ludewig, F; Dorbolo, S

2014-09-12

We study experimentally how the bouncing dynamics of a hollow ball on a vibrating plate is modified when it is partially filled with liquid or grains. Whereas empty and liquid-filled balls display a dominant chaotic dynamics, a ball with grains exhibits a rich variety of stationary states, determined by the grain size and filling volume. In the collisional regime, i.e., when the energy injected to the system is mainly dissipated by interparticle collisions, an unexpected period-1 orbit appears independently of the vibration conditions, over a wide range. This is a self-regulated state driven by the formation and collapse of a granular gas within the ball during one cycle. In the frictional regime (dissipation dominated by friction), the grains move collectively and generate different patterns and steady modes: oscillons, waves, period doubling, etc. From a phase diagram and a geometrical analysis, we deduce that these modes are the result of a coupling (synchronization) between the vibrating plate frequency and the trajectory followed by the particles inside the cavity.

Dynamics of a Grain-Filled Ball on a Vibrating Plate

NASA Astrophysics Data System (ADS)

Pacheco-Vázquez, F.; Ludewig, F.; Dorbolo, S.

2014-09-01

We study experimentally how the bouncing dynamics of a hollow ball on a vibrating plate is modified when it is partially filled with liquid or grains. Whereas empty and liquid-filled balls display a dominant chaotic dynamics, a ball with grains exhibits a rich variety of stationary states, determined by the grain size and filling volume. In the collisional regime, i.e., when the energy injected to the system is mainly dissipated by interparticle collisions, an unexpected period-1 orbit appears independently of the vibration conditions, over a wide range. This is a self-regulated state driven by the formation and collapse of a granular gas within the ball during one cycle. In the frictional regime (dissipation dominated by friction), the grains move collectively and generate different patterns and steady modes: oscillons, waves, period doubling, etc. From a phase diagram and a geometrical analysis, we deduce that these modes are the result of a coupling (synchronization) between the vibrating plate frequency and the trajectory followed by the particles inside the cavity.

Active mode locking of quantum cascade lasers in an external ring cavity.

PubMed

Revin, D G; Hemingway, M; Wang, Y; Cockburn, J W; Belyanin, A

2016-05-05

Stable ultrashort light pulses and frequency combs generated by mode-locked lasers have many important applications including high-resolution spectroscopy, fast chemical detection and identification, studies of ultrafast processes, and laser metrology. While compact mode-locked lasers emitting in the visible and near infrared range have revolutionized photonic technologies, the systems operating in the mid-infrared range where most gases have their strong absorption lines, are bulky and expensive and rely on nonlinear frequency down-conversion. Quantum cascade lasers are the most powerful and versatile compact light sources in the mid-infrared range, yet achieving their mode-locked operation remains a challenge, despite dedicated effort. Here we report the demonstration of active mode locking of an external-cavity quantum cascade laser. The laser operates in the mode-locked regime at room temperature and over the full dynamic range of injection currents.

Active mode locking of quantum cascade lasers in an external ring cavity

PubMed Central

Revin, D. G.; Hemingway, M.; Wang, Y.; Cockburn, J. W.; Belyanin, A.

2016-01-01

Stable ultrashort light pulses and frequency combs generated by mode-locked lasers have many important applications including high-resolution spectroscopy, fast chemical detection and identification, studies of ultrafast processes, and laser metrology. While compact mode-locked lasers emitting in the visible and near infrared range have revolutionized photonic technologies, the systems operating in the mid-infrared range where most gases have their strong absorption lines, are bulky and expensive and rely on nonlinear frequency down-conversion. Quantum cascade lasers are the most powerful and versatile compact light sources in the mid-infrared range, yet achieving their mode-locked operation remains a challenge, despite dedicated effort. Here we report the demonstration of active mode locking of an external-cavity quantum cascade laser. The laser operates in the mode-locked regime at room temperature and over the full dynamic range of injection currents. PMID:27147409

Improved plasma accelerator

NASA Technical Reports Server (NTRS)

Cheng, D. Y.

1971-01-01

Converging, coaxial accelerator electrode configuration operates in vacuum as plasma gun. Plasma forms by periodic injections of high pressure gas that is ionized by electrical discharges. Deflagration mode of discharge provides acceleration, and converging contours of plasma gun provide focusing.

Human factors engineering and design validation for the redesigned follitropin alfa pen injection device.

PubMed

Mahony, Mary C; Patterson, Patricia; Hayward, Brooke; North, Robert; Green, Dawne

2015-05-01

To demonstrate, using human factors engineering (HFE), that a redesigned, pre-filled, ready-to-use, pre-asembled follitropin alfa pen can be used to administer prescribed follitropin alfa doses safely and accurately. A failure modes and effects analysis identified hazards and harms potentially caused by use errors; risk-control measures were implemented to ensure acceptable device use risk management. Participants were women with infertility, their significant others, and fertility nurse (FN) professionals. Preliminary testing included 'Instructions for Use' (IFU) and pre-validation studies. Validation studies used simulated injections in a representative use environment; participants received prior training on pen use. User performance in preliminary testing led to IFU revisions and a change to outer needle cap design to mitigate needle stick potential. In the first validation study (49 users, 343 simulated injections), in the FN group, one observed critical use error resulted in a device design modification and another in an IFU change. A second validation study tested the mitigation strategies; previously reported use errors were not repeated. Through an iterative process involving a series of studies, modifications were made to the pen design and IFU. Simulated-use testing demonstrated that the redesigned pen can be used to administer follitropin alfa effectively and safely.

Dual-mode nonlinear instability analysis of a confined planar liquid sheet sandwiched between two gas streams of unequal velocities and prediction of droplet size and velocity distribution using maximum entropy formulation

NASA Astrophysics Data System (ADS)

Dasgupta, Debayan; Nath, Sujit; Bhanja, Dipankar

2018-04-01

Twin fluid atomizers utilize the kinetic energy of high speed gases to disintegrate a liquid sheet into fine uniform droplets. Quite often, the gas streams are injected at unequal velocities to enhance the aerodynamic interaction between the liquid sheet and surrounding atmosphere. In order to improve the mixing characteristics, practical atomizers confine the gas flows within ducts. Though the liquid sheet coming out of an injector is usually annular in shape, it can be considered to be planar as the mean radius of curvature is much larger than the sheet thickness. There are numerous studies on breakup of the planar liquid sheet, but none of them considered the simultaneous effects of confinement and unequal gas velocities on the spray characteristics. The present study performs a nonlinear temporal analysis of instabilities in the planar liquid sheet, produced by two co-flowing gas streams moving with unequal velocities within two solid walls. The results show that the para-sinuous mode dominates the breakup process at all flow conditions over the para-varicose mode of breakup. The sheet pattern is strongly influenced by gas velocities, particularly for the para-varicose mode. Spray characteristics are influenced by both gas velocity and proximity to the confining wall, but the former has a much more pronounced effect on droplet size. An increase in the difference between gas velocities at two interfaces drastically shifts the droplet size distribution toward finer droplets. Moreover, asymmetry in gas phase velocities affects the droplet velocity distribution more, only at low liquid Weber numbers for the input conditions chosen in the present study.

Assessment of Well Safety from Pressure and Temperature-Induced Damage during CO2 Injection in Deep Saline Aquifers

NASA Astrophysics Data System (ADS)

Singh, A. K.; Delfs, J.; Goerke, U.; Kolditz, O.

2013-12-01

Carbon dioxide Capture and Storage (CCS) technology is known for disposing a specific amount of CO2 from industrial release of flue gases into a suitable storage where it stays for a defined period of time in a safe way. Types of storage sites for CO2 are depleted hydrocarbon reservoirs, unmineable coal seams and saline aquifers. In this poster, we address the problem of CO2 sequestration into deep saline aquifers. The main advantage of this kind of site for the CO2 sequestration is its widespread geographic distribution. However, saline aquifers are very poorly characterized and typically located at one kilometer depth below the earth's surface. To demonstrate that supercritical CO2 injection into deep saline aquifers is technically and environmentally safe, it is required to perform thermo-hydro-mechanical analysis of failure moods with numerical models. In the poster, we present simple process-catching benchmark for testing the scenario of compressed CO2 injection into a multi- layered saline aquifer.The pores of the deformable matrix are initially filled with saline water at hydrostatic pressure and geothermal temperature conditions. This benchmark investigates (i) how the mechanical and thermal stresses enhance the permeability for CO2 migration; and (ii) subsequent failures mode, i.e., tensile, and shear failures. The tensile failure occurs when pore fluid pressure exceeds the principle stress whereas the Mohr-Coulomb failure criterion defines the shear failure mode. The thermo-hydro-mechanical (THM) model is based on a ';multi-componential flow' module . The coupled system of balance equations is solvedin the monolithic way. The Galerkin finite element approach is used for spatial discretization, whereas temporal discretization is performed with a generalized single step scheme. This numerical module has been implemented in the open-source scientific software OpenGeoSys.

PIC simulations of wave-particle interactions with an initial electron velocity distribution from a kinetic ring current model

DOE PAGES

Yu, Yiqun; Delzanno, Gian Luca; Jordanova, Vania Koleva; ...

2017-07-15

Whistler wave-particle interactions play an important role in the Earth inner magnetospheric dynamics and have been the subject of numerous investigations. By running a global kinetic ring current model (RAM-SCB) in a storm event occurred on Oct 23–24 2002, we obtain the ring current electron distribution at a selected location at MLT of 9 and L of 6 where the electron distribution is composed of a warm population in the form of a partial ring in the velocity space (with energy around 15 keV) in addition to a cool population with a Maxwellian-like distribution. The warm population is likely frommore » the injected plasma sheet electrons during substorm injections that supply fresh source to the inner magnetosphere. These electron distributions are then used as input in an implicit particle-in-cell code (iPIC3D) to study whistler-wave generation and the subsequent wave-particle interactions. Here, we find that whistler waves are excited and propagate in the quasi-parallel direction along the background magnetic field. Several different wave modes are instantaneously generated with different growth rates and frequencies. The wave mode at the maximum growth rate has a frequency around 0.62ω ce, which corresponds to a parallel resonant energy of 2.5 keV. Linear theory analysis of wave growth is in excellent agreement with the simulation results. These waves grow initially due to the injected warm electrons and are later damped due to cyclotron absorption by electrons whose energy is close to the resonant energy and can effectively attenuate waves. The warm electron population overall experiences net energy loss and anisotropy drop while moving along the diffusion surfaces towards regions of lower phase space density, while the cool electron population undergoes heating when the waves grow, suggesting the cross-population interactions.« less

PIC simulations of wave-particle interactions with an initial electron velocity distribution from a kinetic ring current model

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

Yu, Yiqun; Delzanno, Gian Luca; Jordanova, Vania Koleva

Whistler wave-particle interactions play an important role in the Earth inner magnetospheric dynamics and have been the subject of numerous investigations. By running a global kinetic ring current model (RAM-SCB) in a storm event occurred on Oct 23–24 2002, we obtain the ring current electron distribution at a selected location at MLT of 9 and L of 6 where the electron distribution is composed of a warm population in the form of a partial ring in the velocity space (with energy around 15 keV) in addition to a cool population with a Maxwellian-like distribution. The warm population is likely frommore » the injected plasma sheet electrons during substorm injections that supply fresh source to the inner magnetosphere. These electron distributions are then used as input in an implicit particle-in-cell code (iPIC3D) to study whistler-wave generation and the subsequent wave-particle interactions. Here, we find that whistler waves are excited and propagate in the quasi-parallel direction along the background magnetic field. Several different wave modes are instantaneously generated with different growth rates and frequencies. The wave mode at the maximum growth rate has a frequency around 0.62ω ce, which corresponds to a parallel resonant energy of 2.5 keV. Linear theory analysis of wave growth is in excellent agreement with the simulation results. These waves grow initially due to the injected warm electrons and are later damped due to cyclotron absorption by electrons whose energy is close to the resonant energy and can effectively attenuate waves. The warm electron population overall experiences net energy loss and anisotropy drop while moving along the diffusion surfaces towards regions of lower phase space density, while the cool electron population undergoes heating when the waves grow, suggesting the cross-population interactions.« less

Lightning Pin Injection Testing on MOSFETS

NASA Technical Reports Server (NTRS)

Ely, Jay J.; Nguyen, Truong X.; Szatkowski, George N.; Koppen, Sandra V.; Mielnik, John J.; Vaughan, Roger K.; Wysocki, Philip F.; Celaya, Jose R.; Saha, Sankalita

2009-01-01

Lightning transients were pin-injected into metal-oxide-semiconductor field-effect transistors (MOSFETs) to induce fault modes. This report documents the test process and results, and provides a basis for subsequent lightning tests. MOSFETs may be present in DC-DC power supplies and electromechanical actuator circuits that may be used on board aircraft. Results show that unprotected MOSFET Gates are susceptible to failure, even when installed in systems in well-shielded and partial-shielded locations. MOSFET Drains and Sources are significantly less susceptible. Device impedance decreased (current increased) after every failure. Such a failure mode may lead to cascading failures, as the damaged MOSFET may allow excessive current to flow through other circuitry. Preliminary assessments on a MOSFET subjected to 20-stroke pin-injection testing demonstrate that Breakdown Voltage, Leakage Current and Threshold Voltage characteristics show damage, while the device continues to meet manufacturer performance specifications. The purpose of this research is to develop validated tools, technologies, and techniques for automated detection, diagnosis and prognosis that enable mitigation of adverse events during flight, such as from lightning transients; and to understand the interplay between lightning-induced surges and aging (i.e. humidity, vibration thermal stress, etc.) on component degradation.

Active locking and entanglement in type II optical parametric oscillators

NASA Astrophysics Data System (ADS)

Ruiz-Rivas, Joaquín; de Valcárcel, Germán J.; Navarrete-Benlloch, Carlos

2018-02-01

Type II optical parametric oscillators are amongst the highest-quality sources of quantum-correlated light. In particular, when pumped above threshold, such devices generate a pair of bright orthogonally-polarized beams with strong continuous-variable entanglement. However, these sources are of limited practical use, because the entangled beams emerge with different frequencies and a diffusing phase difference. It has been proven that the use of an internal wave-plate coupling the modes with orthogonal polarization is capable of locking the frequencies of the emerging beams to half the pump frequency, as well as reducing the phase-difference diffusion, at the expense of reducing the entanglement levels. In this work we characterize theoretically an alternative locking mechanism: the injection of a laser at half the pump frequency. Apart from being less invasive, this method should allow for an easier real-time experimental control. We show that such an injection is capable of generating the desired phase locking between the emerging beams, while still allowing for large levels of entanglement. Moreover, we find an additional region of the parameter space (at relatively large injections) where a mode with well defined polarization is in a highly amplitude-squeezed state.

Disruption mitigation and avoidance at ASDEX Upgrade

NASA Astrophysics Data System (ADS)

Maraschek, M.; Pautasso, G.; Esposito, B.; Granucci, G.; Stober, J.; Treutterer, W.

2009-11-01

Disruptions are a major concern for tokamaks and in particular for ITER. They cause high heat loads during the thermal quench and high mechanical forces during the subsequent current quench. The generation and loss of runaway electrons (highly accelerated electrons carrying large fractions of the plasma current) can produce damage to the vessel structures. Therefore, schemes are implemented in present tokamaks to mitigate or to even avoid them. Mitigation has been proven to be effective through the injection of noble gases causing a reduction of the thermal heat load by radiation and a reduction of the mechanical forces. In addition 25% of the required density for the collisional suppression of runaways in ITER has been reached. For the trigger of the noble gas injection a locked mode detector is routinely used at ASDEX Upgrade. An extension to more complex precursors is planed. A different approach has been used for disruption avoidance by injecting ECRH triggered by the loop voltage increase before the disruption. The avoidance of an ongoing density limit disruption has been achieved when the ECRH is deposited at resonant surfaces where MHD modes, such as the m=2/n=1, occur. Present schemes for the mitigation and eventually avoidance of disruptions will be discussed.

The role of MHD in 3D aspects of massive gas injection

DOE PAGES

Izzo, Valerie A.; Parks, P. B.; Eidietis, Nicholas W.; ...

2015-06-26

Simulations of massive gas injection (MGI) for disruption mitigation in DIII-D are carried out to compare the toroidal peaking of radiated power for the cases of one and two gas jets. The radiation toroidal peaking factor (TPF) results from a combination of the distribution of impurities and the distribution of heat flux associated with then =1 mode. The injected impurities are found to spread helically along field lines preferentially toward the high-field-side, which is explained in terms of a nozzle equation. In light of this mechanism, reversing the current direction also reverses the toroidal direction of impurity spreading. During themore » pre-thermal quench phase of the disruption, the toroidal peaking of radiated power is reduced in the straightforward manner by increasing from one to two gas jets. However, during the thermal quench phase, reduction in the TPF is achieved only for a particular arrangement of the two gas valves with respect to the field line pitch. In particular, the relationship between the two valve locations and the 1/1 mode phase is critical, where gas valve spacing that is coherent with 1/1 symmetry effectively reduces TPF.« less

Exploration of the Super H-mode regime on DIII-D and potential advantages for burning plasma devices

DOE PAGES

Solomon, W. M.; Snyder, P. B.; Bortolon, A.; ...

2016-03-25

In a new high pedestal regime ("Super H-mode") we predicted and accessed DIII-D. Super H-mode was first achieved on DIII-D using a quiescent H-mode edge, enabling a smooth trajectory through pedestal parameter space. By exploiting Super H-mode, it has been possible to access high pedestal pressures at high normalized densities. And while elimination of Edge localized modes (ELMs) is beneficial for Super H-mode, it may not be a requirement, as recent experiments have maintained high pedestals with ELMs triggered by lithium granule injection. Simulations using TGLF for core transport and the EPED model for the pedestal find that ITER canmore » benefit from the improved performance associated with Super H-mode, with increased values of fusion power and gain possible. In similar studies demonstrate that the Super H-mode pedestal can be advantageous for a steady-state power plant, by providing a path to increasing the bootstrap current while simultaneously reducing the demands on the core physics performance.« less

Long-term treatment patterns of testosterone replacement medications.

PubMed

Donatucci, Craig; Cui, Zhanglin; Fang, Yun; Muram, David

2014-08-01

Testosterone replacement therapy (TRT) is prescribed to men diagnosed with hypogonadism to alleviate symptoms, improve quality of life, and improve overall health. However, most men use TRT for only a short duration. To evaluate the long-term treatment patterns in hypogonadal men using topical TRT or short-lasting TRT injections. Using the Truven MarketScan(®) Database, 15,435 men who received their first (index) topical TRT prescription and 517 men who received their short-lasting TRT injection index prescription in 2009 were followed from 12 to 30 months after treatment initiation. Treatment interruption was defined as a medication gap of >30 days. Patients who remained off treatment were classified as having discontinued treatment. Patients who restarted therapy after 30 days were classified as cyclic users. Patients were required to have continuous insurance coverage during 1 year prior to treatment initiation and at least 1 year afterward. Main outcome measures were length of therapy, discontinuation, and restarts of topical TRT or short-lasting TRT injections. The patient characteristics were similar for patients who received topical TRT or short-lasting TRT injections. Of the patients who discontinued therapy during the follow-up period, the percentages of patients who were still on therapy after 3 months were 52% and 31% for topical TRT and short-lasting TRT users, respectively. For cyclic users, there was an attrition rate of approximately 40% to 50% of patients in each cycle. For both topical TRT and short-lasting TRT injections, the gap between stopping and restarting therapy tended to decrease over time. In this analysis, high discontinuation rates were observed. The treatment pattern of TRT may be related to the disease state rather than dosing, daily use, or mode of administration. © 2014 International Society for Sexual Medicine.

Extravasation of contrast medium during CT examination: an observational case-control study

PubMed Central

Alami, Zayneb; Nasri, Siham; Ahid, Samir; Kacem, Hanane Hadj

2015-01-01

Introduction Extravasation is an adverse reaction to intravenous injection of contrast medium (CM) during CT examination. The objectives of this study are to determine the frequency, management and outcomes of extravasations and to assess risk factors for extravasation. Methods Every incident of extravasation which occurred between March 2012 and March 31, 2013 was recorded in an extravasation form. Ethics Committee approval was obtained and the patients gave their consent to participate in the study. Data collected in the form included patients’ age, sex, comorbidities, symptoms, CM used, injection mode, site and rate, extravasated volume, location of extravasation, severity of injury, treatment and patient outcome. Each case was matched with 4 controls of the same age ± 5 years and the same gender when possible. Results Extravasation occurred in 18 (7 women, 11 men) out of 2,000 injections of CM (0.9%) with a median age of 53 (10-78) years. Automated injection was performed in all cases with a mean rate of 1.7ml/s. Large extravasated volumes (≥ 50ml) were more observed in patients undergoing CT angiography (28.6% vs. 6.6%, although not significant P=0.112). Multivariate analysis revealed a significant association between patients with cardiac diseases and extravasation (OR: 7.3, 95% CI (1.09-49.05), P=0.04) whereas the injection rate is a protective factor from extravasation (P=0.002). Conclusion Extravasation of CM results in mild to moderate adverse effects in all cases. Our study suggests that patients with cardiac disease are more predisposed to contrast extravasation than others. Further and larger studies are needed to confirm this trend. PMID:26090047

Strontium-rich injectable hybrid system for bone regeneration.

PubMed

Neves, Nuno; Campos, Bruno B; Almeida, Isabel F; Costa, Paulo C; Cabral, Abel Trigo; Barbosa, Mário A; Ribeiro, Cristina C

2016-02-01

Current challenges in the development of scaffolds for bone regeneration include the engineering of materials that can withstand normal dynamic physiological mechanical stresses exerted on the bone and provide a matrix capable of supporting cell migration and tissue ingrowth. The objective of the present work was to develop and characterize a hybrid polymer–ceramic injectable system that consists of an alginate matrix crosslinked in situ in the presence of strontium(Sr), incorporating a ceramic reinforcement in the form of Sr-rich microspheres. The incorporation of Sr in the microspheres and in the vehicle relies on the growing evidence that Sr has beneficial effects in bone remodeling and in the treatment of osteopenic disorders and osteoporosis. Sr-rich porous hydroxyapatite microspheres with a uniform size and a mean diameter of 555 μm were prepared, and their compression strength and friability tested. A 3.5% (w/v) ultrapure sodium alginate solution was used as the vehicle and its in situ gelation was promoted by the addition of calcium (Ca) or Sr carbonate and Glucone-δ-lactone. Gelation times varied with temperature and crosslinking agent, being slower for Sr than for Ca, but adequate for injection in both cases. Injectability was evaluated using a device employed in vertebroplasty surgical procedures, coupled to a texture analyzer in compression mode. Compositions with 35%w of microspheres presented the best compromise between injectability and compression strength of the system, the force required to extrude it being lower than 100 N.Micro CT analysis revealed a homogeneous distribution of the microspheres inside the vehicle, and a mean inter-microspheres space of 220 μm. DMA results showed that elastic behavior of the hybrid is over the viscous one and that the higher storage modulus was obtained for the 3.5%Alg–35%Sr-HAp-Sr formulation.

All optical mode controllable Er-doped random fiber laser with distributed Bragg gratings.

PubMed

Zhang, W L; Ma, R; Tang, C H; Rao, Y J; Zeng, X P; Yang, Z J; Wang, Z N; Gong, Y; Wang, Y S

2015-07-01

An all-optical method to control the lasing modes of Er-doped random fiber lasers (RFLs) is proposed and demonstrated. In the RFL, an Er-doped fiber (EDF) recoded with randomly separated fiber Bragg gratings (FBG) is used as the gain medium and randomly distributed reflectors, as well as the controllable element. By combining random feedback of the FBG array and Fresnel feedback of a cleaved fiber end, multi-mode coherent random lasing is obtained with a threshold of 14 mW and power efficiency of 14.4%. Moreover, a laterally-injected control light is used to induce local gain perturbation, providing additional gain for certain random resonance modes. As a result, active mode selection of the RFL is realized by changing locations of the laser cavity that is exposed to the control light.

Multiwavelength self-pulsating fibre laser based on cascaded SPM spectral broadening and filtering

NASA Astrophysics Data System (ADS)

Rochette, Martin; Sun, Kai; Hernández-Cordero, Juan; Chen, Lawrence R.

2008-06-01

We experimentally demonstrate the operation of a laser based on self-phase modulation followed by offset spectral filtering. This laser has three operation modes: a continuous-wave mode, a self-pulsating mode where the laser self ignites and produces pulses, and a pulse-buffering mode where no new pulse is formed from spontaneous emission noise but only pulses already propagating or pulses injected in the laser cavity can be sustained. In the self-pulsating and pulse-buffering modes, the laser is multi-wavelength and continuously tunable over the entire gain band of the amplifiers. The output pulse width is quasi transform-limited with respect to the spectral-width of the filters used in the cavity. Overall, this device provides a simple alternative to pulsed laser source and also represents a promising approach for signal buffering.

Microdisk Injection Lasers for the 1.27-μm Spectral Range

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

Kryzhanovskaya, N. V.; Maximov, M. V.; Blokhin, S. A.

2016-03-15

Microdisk injection lasers on GaAs substrates, with a minimum diameter of 15 μm and an active region based on InAs/InGaAs quantum dots, are fabricated. The lasers operate in the continuous-wave mode at room temperature without external cooling. The lasing wavelength is around 1.27 μm at a minimum threshold current of 1.6 mA. The specific thermal resistance is estimated to be 5 × 10–3 °C cm{sup 2}/W.

Injection mode-locking Ti-sapphire laser system

DOEpatents

Hovater, James Curtis; Poelker, Bernard Matthew

2002-01-01

According to the present invention there is provided an injection modelocking Ti-sapphire laser system that produces a unidirectional laser oscillation through the application of a ring cavity laser that incorporates no intracavity devices to achieve unidirectional oscillation. An argon-ion or doubled Nd:YVO.sub.4 laser preferably serves as the pump laser and a gain-switched diode laser serves as the seed laser. A method for operating such a laser system to produce a unidirectional oscillating is also described.

Easily constructed spectroelectrochemical cell for batch and flow injection analyses.

PubMed

Flowers, Paul A; Maynor, Margaret A; Owens, Donald E

2002-02-01

The design and performance of an easily constructed spectroelectrochemical cell suitable for batch and flow injection measurements are described. The cell is fabricated from a commercially available 5-mm quartz cuvette and employs 60 ppi reticulated vitreous carbon as the working electrode, resulting in a reasonable compromise between optical sensitivity and thin-layer electrochemical behavior. The spectroelectrochemical traits of the cell in both batch and flow modes were evaluated using aqueous ferricyanide and compare favorably to those reported previously for similar cells.

Performance of ITER as a burning plasma experiment

NASA Astrophysics Data System (ADS)

Shimada, M.; Mukhovatov, V.; Federici, G.; Gribov, Y.; Kukushkin, A.; Murakami, Y.; Polevoi, A.; Pustovitov, V.; Sengoku, S.; Sugihara, M.

2004-02-01

Recent performance analysis has improved confidence in achieving Q (= fusion power/auxiliary heating power)geq 10 in inductive operation in ITER. Performance analysis based on empirical scalings shows the feasibility of achieving Q geq 10 in inductive operation, particularly with improved modelling of helium exhaust. Analysis has also indicated the possibility that ITER can potentially demonstrate Q ~ 50, enabling studies of self-heated plasmas. Theory-based core modelling indicates the need for a high pedestal temperature (3.2-5.3 keV) to achieve Q geq 10, which is in the range of projections with presently available pedestal scalings. Pellet injection from the high-field side would be useful in enhancing Q and reducing edge localized mode (ELM) heat load in high plasma current operation. If the ELM heat load is not acceptable, it could be made tolerable by further tilting the target plate. Steady state operation scenarios at Q = 5 have been developed with modest requirements on confinement improvement and beta (HH98(y,2) geq 1.3 and bgrN geq 2.6). Stabilization of the resistive wall modes (RWMs), required in such regimes, is feasible with the present saddle coils and power supplies with double-wall structures taken into account. Recent analysis shows a potential of high power steady state operation with a fusion power of 0.7 GW at Q ~ 8. Achievement of the required bgrN ~ 3.6 by RWM stabilization is a possibility. Further analysis is also needed on reduction of the divertor target heat load.

Whistler mode plasma waves observed on Electron Echo 2

NASA Technical Reports Server (NTRS)

Monson, S. J.; Kellogg, P. J.; Cartwright, D. G.

1976-01-01

Observations of whistler-mode waves associated with beams of electrons injected into the ionosphere are reported. The measurements are from the plasma-wave experiments carried on the Electron Echo 2 sounding rocket launched on September 24, 1972. Over 2000 electron injections were made with durations of 8 ms and 64 ms and pitch angles from 0 to 180 deg. The electric field receivers carried on the ejected nose cone observed strong whistler waves in the range from less than 100 kHz up to the electron cyclotron frequency of 1400 kHz. The whistler characteristics fall into four distinct types depending on pitch angle and gun energy. Both frequency and amplitude showed strong dependence on time from the start of the pulse and pitch angle. Cases of enhancement at the leading edge of a gun pulse, growth during a pulse, and echoes after the end of a pulse were all observed.

Focal plane infrared readout circuit with automatic background suppression

NASA Technical Reports Server (NTRS)

Pain, Bedabrata (Inventor); Yang, Guang (Inventor); Sun, Chao (Inventor); Shaw, Timothy J. (Inventor); Wrigley, Chris J. (Inventor)

2002-01-01

A circuit for reading out a signal from an infrared detector includes a current-mode background-signal subtracting circuit having a current memory which can be enabled to sample and store a dark level signal from the infrared detector during a calibration phase. The signal stored by the current memory is subtracted from a signal received from the infrared detector during an imaging phase. The circuit also includes a buffered direct injection input circuit and a differential voltage readout section. By performing most of the background signal estimation and subtraction in a current mode, a low gain can be provided by the buffered direct injection input circuit to keep the gain of the background signal relatively small, while a higher gain is provided by the differential voltage readout circuit. An array of such readout circuits can be used in an imager having an array of infrared detectors. The readout circuits can provide a high effective handling capacity.

Propagation Dynamics Associated with Resonant Magnetic Perturbation Fields in High-Confinement Mode Plasmas inside the KSTAR Tokamak.

PubMed

Xiao, W W; Evans, T E; Tynan, G R; Yoon, S W; Jeon, Y M; Ko, W H; Nam, Y U; Oh, Y K

2017-11-17

The propagation dynamics of resonant magnetic perturbation fields in KSTAR H-mode plasmas with injection of small edge perturbations produced by a supersonic molecular beam injection is reported for the first time. The results show that the perturbation field first excites a plasma response on the q=3 magnetic surface and then propagates inward to the q=2 surface with a radially averaged propagation velocity of resonant magnetic perturbations field equal to 32.5  m/ s. As a result, the perturbation field brakes the toroidal rotation on the q=3 surface first causing a momentum transport perturbation that propagates both inward and outward. A higher density fluctuation level is observed. The propagation velocity of the resonant magnetic perturbations field is larger than the radial propagation velocity of the perturbation in the toroidal rotation.

Initial results from the LAPD wave-particle experiment and simulation

NASA Astrophysics Data System (ADS)

Bortnik, J.; Tao, X.; Albert, J. M.; Thorne, R. M.; Gekelman, W. N.; Pribyl, P.; Van Compernolle, B.

2011-12-01

We present the initial results obtained from a unique experiment-theory project. This project is designed to study the detailed nature of the wave-particle interactions between energetic electrons and whistler-mode waves. Using the Large-Plasma device at UCLA, whistler mode waves are injected into one end of the machine and a beam of energetic electrons is injected at the opposite ends. When the first-order resonance condition is met, the electron beam is scattered, which is measured with a novel energy-pitch-angle analyzer. To support the experiment, a flexible test-particle code is constructed which is able to quantify the scattering of charged particles in response to any distribution of waves, in an arbitrary field geometry. The results of the experiment are discussed and placed into the context of space physics and specifically the upcoming Radiation Belt Storm Probes mission.

High Pressure Coolant Injection (HPCI) System Risk-Based Inspection Guide for Browns Ferry Nuclear Power Station

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

Wong, S.; DiBiasio, A.; Gunther, W.

1993-09-01

The High Pressure Coolant Injection (HPCI) system has been examined from a risk perspective. A System Risk-Based Inspection Guide (S-RIG) has been developed as an aid to HPCI system inspections at the Browns Ferry Nuclear Power Plant, Units 1, 2 and 3. The role of. the HPCI system in mitigating accidents is discussed in this S-RIG, along with insights on identified risk-based failure modes which could prevent proper operation of the system. The S-RIG provides a review of industry-wide operating experience, including plant-specific illustrative examples to augment the PRA and operational considerations in identifying a catalogue of basic PRA failuremore » modes for the HPCI system. It is designed to be used as a reference for routine inspections, self-initiated safety system functional inspections (SSFIs), and the evaluation of risk significance of component failures at the nuclear power plant.« less

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

Solomon, W. M., E-mail: solomon@fusion.gat.com; Bortolon, A.; Grierson, B. A.

A new high pedestal regime (“Super H-mode”) has been predicted and accessed on DIII-D. Super H-mode was first achieved on DIII-D using a quiescent H-mode edge, enabling a smooth trajectory through pedestal parameter space. By exploiting Super H-mode, it has been possible to access high pedestal pressures at high normalized densities. While elimination of Edge localized modes (ELMs) is beneficial for Super H-mode, it may not be a requirement, as recent experiments have maintained high pedestals with ELMs triggered by lithium granule injection. Simulations using TGLF for core transport and the EPED model for the pedestal find that ITER canmore » benefit from the improved performance associated with Super H-mode, with increased values of fusion power and gain possible. Similar studies demonstrate that the Super H-mode pedestal can be advantageous for a steady-state power plant, by providing a path to increasing the bootstrap current while simultaneously reducing the demands on the core physics performance.« less

Subcritical and supercritical fuel injection and mixing in single and binary species systems

NASA Astrophysics Data System (ADS)

Roy, Arnab

Subcritical and supercritical fluid injection using a single round injector into a quiescent atmosphere comprising single and binary species was investigated using optical diagnostics. Different disintegration and mixing modes are expected for the two cases. In the binary species case, the atmosphere comprised an inert gas of a different composition than that of the injected fluid. In single species case, the atmosphere consisted of the same species as that of the injected fluid. Density values were quantified and density gradient profiles were inferred from the experimental data. A novel method was applied for the detection of detailed structures throughout the entire jet center plane. Various combinations of injectant and chamber conditions were tested and a wide range of density ratios were covered. The subcritical cases demonstrated the importance of surface tension and inertial forces, while the supercritical cases showed no signs of surface tension and, in most situations, resembled the mixing characteristics of a gaseous jet injected into a gaseous environment. A comparison between the single and binary species systems has also been provided. A detailed laser calibration procedure was undertaken to account for the laser absorption through the gas and liquid phases and for fluorescence in the non-linear excitation regime for high laser pulse energy. Core lengths were measured for binary species cases and correlated with visualization results. An eigenvalue approach was taken to determine the location of maximum gradients for determining the core length. Jet divergence angles were also calculated and were found to increase with chamber-to-injectant density ratio for both systems. A model was proposed for the spreading angle dependence on density ratio for both single and binary species systems and was compared to existing theoretical studies and experimental work. Finally, a linear stability analysis was performed for the jet injected into both subcritical and supercritical atmospheres. The subcritical cases showed good correlation with previous and current experimental results. The supercritical solutions, which have not yet been solved earlier by researchers, are found here through an asymptotic solution of the dispersion equation for exceedingly high Weber numbers.

The ABCD matrix for parabolic reflectors and its application to astigmatism free four-mirror cavities

NASA Astrophysics Data System (ADS)

Dupraz, K.; Cassou, K.; Martens, A.; Zomer, F.

2015-10-01

The ABCD matrix for parabolic reflectors is derived for any incident angles. It is used in numerical studies of four-mirror cavities composed of two flat and two parabolic mirrors. Constraints related to laser beam injection efficiency, optical stability, cavity-mode, beam-waist size and high stacking power are satisfied. A dedicated alignment procedure leading to stigmatic cavity-modes is employed to overcome issues related to the optical alignment of parabolic reflectors.

Injection-locking of terahertz quantum cascade lasers up to 35GHz using RF amplitude modulation.

PubMed

Gellie, Pierre; Barbieri, Stefano; Lampin, Jean-François; Filloux, Pascal; Manquest, Christophe; Sirtori, Carlo; Sagnes, Isabelle; Khanna, Suraj P; Linfield, Edmund H; Davies, A Giles; Beere, Harvey; Ritchie, David

2010-09-27

We demonstrate that the cavity resonance frequency - the round-trip frequency - of Terahertz quantum cascade lasers can be injection-locked by direct modulation of the bias current using an RF source. Metal-metal and single-plasmon waveguide devices with roundtrip frequencies up to 35GHz have been studied, and show locking ranges above 200MHz. Inside this locking range the laser round-trip frequency is phase-locked, with a phase noise determined by the RF-synthesizer. We find a square-root dependence of the locking range with RF-power in agreement with classical injection-locking theory. These results are discussed in the context of mode-locking operation.

ELF wave production by an electron beam emitting rocket system and its suppression on auroral field lines - Evidence for Alfven and drift waves

NASA Astrophysics Data System (ADS)

Winckler, J. R.; Erickson, K. N.; Abe, Y.; Steffen, J. E.; Malcolm, P. R.

1985-07-01

Orthogonal probes on a free-flying plasma diagnostics payload are used to study ELF electric disturbances in the auroral ionosphere that are due to the injection of powerful electron beams. Frequency spectrograms are presented for various pitch angles, pulsing characteristics, and other properties of the injected beams; the large scale DC ionospheric convection electric field is measured, together with auroral particle precipitation, visual auroral forms, and ionospheric parameters. In view of the experimental results obtained, it is postulated that the observed ELF waves are in the Alfven and drift modes, and are generated by the positive vehicle potential during beam injection.

Charcateristics of Plasma Waves Excited During Gas Release and Plasma Injection Into The Ionosphere

NASA Astrophysics Data System (ADS)

Klos, Z.; Gdalevich, G. L.; Mikhailov, I.

Waves in broad frequency range are generated during the injection of fast plasma as well as release of neutral gas into ionosphere from the spacecraft. The excited wave modes depend on the environmental plasma parameters, geometry of injection as well as on the rate of ionisation of plasma in the stream. The neutral xenon gas was released from the board of the ACTIVE satellite (in 1989) and parallel with the release process the VLF as well as HF waves were diagnosed. On the other hand the xenon plasma from gun generator was injected into the ionosphere from the board of APEX satellite (in 1991) and also broad frequency range of emission was registered. In the present paper are compared the plasma waves characteristics observed in these two types of experiments.

Initial Thomson Scattering Survey of Local Helicity Injection and Ohmic Plasmas at the Pegasus Toroidal Experiment

NASA Astrophysics Data System (ADS)

Schlossberg, D. J.; Bodner, G. M.; Bongard, M. W.; Fonck, R. J.; Winz, G. R.

2014-10-01

A multipoint Thomson scattering diagnostic has recently been installed on the Pegasus ST. The system utilizes a frequency-doubled Nd:YAG laser (λ0 ~ 532 nm), spectrometers with volume phase holographic gratings, and a gated, intensified CCD camera. It provides measurements of Te and ne at 8 spatial locations for each spectrometer once per discharge. A new multiple aperture and beam dump system has been implemented to mitigate interference from stray light. This system has provided initial measurements in the core region of plasmas initiated by local helicity injection (LHI), as well as conventional Ohmic L- and H-mode discharges. Multi-shot averages of low-density (ne ~ 3 ×1018 m-3) , Ip ~ 0 . 1 MA LHI discharges show central Te ~ 75 eV at the end of the helicity injection phase. Ip ~ 0 . 13 MA Ohmic plasmas at moderate densities (ne ~ 2 ×1019 m-3) have core Te ~ 150 eV in L-mode. Generally, these plasmas do not reach transport equilibrium in the short 25 ms pulse length available. After an L-H transition, strong spectral broadening indicates increasing Te, to values above the range of the present spectrometer system with a high-dispersion VPH grating. Near-term system upgrades will focus on deploying a second spectrometer, with a lower-dispersion grating capable of measuring the 0.1-1.0 keV range. The second spectrometer system will also increase the available number of spatial channels, enabling study of H-mode pedestal structure. Work supported by US DOE Grant DE-FG02-96ER54375.

Tungsten impurity transport experiments in Alcator C-Mod to address high priority research and development for ITER

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

Loarte, A.; Polevoi, A. R.; Hosokawa, M.

2015-05-15

Experiments in Alcator C-Mod tokamak plasmas in the Enhanced D-alpha H-mode regime with ITER-like mid-radius plasma density peaking and Ion Cyclotron Resonant heating, in which tungsten is introduced by the laser blow-off technique, have demonstrated that accumulation of tungsten in the central region of the plasma does not take place in these conditions. The measurements obtained are consistent with anomalous transport dominating tungsten transport except in the central region of the plasma where tungsten transport is neoclassical, as previously observed in other devices with dominant neutral beam injection heating, such as JET and ASDEX Upgrade. In contrast to such results,more » however, the measured scale lengths for plasma temperature and density in the central region of these Alcator C-Mod plasmas, with density profiles relatively flat in the core region due to the lack of core fuelling, are favourable to prevent inter and intra sawtooth tungsten accumulation in this region under dominance of neoclassical transport. Simulations of ITER H-mode plasmas, including both anomalous (modelled by the Gyro-Landau-Fluid code GLF23) and neoclassical transport for main ions and tungsten and with density profiles of similar peaking to those obtained in Alcator C-Mod show that accumulation of tungsten in the central plasma region is also unlikely to occur in stationary ITER H-mode plasmas due to the low fuelling source by the neutral beam injection (injection energy ∼ 1 MeV), which is in good agreement with findings in the Alcator C-Mod experiments.« less

Achievement of radiative feedback control for long-pulse operation on EAST

NASA Astrophysics Data System (ADS)

Wu, K.; Yuan, Q. P.; Xiao, B. J.; Wang, L.; Duan, Y. M.; Chen, J. B.; Zheng, X. W.; Liu, X. J.; Zhang, B.; Xu, J. C.; Luo, Z. P.; Zang, Q.; Li, Y. Y.; Feng, W.; Wu, J. H.; Yang, Z. S.; Zhang, L.; Luo, G.-N.; Gong, X. Z.; Hu, L. Q.; Hu, J. S.; Li, J.

2018-05-01

The active feedback control of radiated power to prevent divertor target plates overheating during long-pulse operation has been developed and implemented on EAST. The radiation control algorithm, with impurity seeding via a supersonic molecular beam injection (SMBI) system, has shown great success in both reliability and stability. By seeding a sequence of short neon (Ne) impurity pulses with the SMBI from the outer mid-plane, the radiated power of the bulk plasma can be well controlled, and the duration of radiative control (feedforward and feedback) is 4.5 s during a discharge of 10 s. Reliable control of the total radiated power of bulk plasma has been successfully achieved in long-pulse upper single null (USN) discharges with a tungsten divertor. The achieved control range of {{f}rad} is 20%–30% in L-mode regimes and 18%–36% in H-mode regimes. The temperature of the divertor target plates was maintained at a low level during the radiative control phase. The peak particle flux on the divertor target was decreased by feedforward Ne injection in the L-mode discharges, while the Ne pulses from the SMBI had no influence on the peak particle flux because of the very small injecting volume. It is shown that although the radiated power increased, no serious reduction of plasma-stored energy or confinement was observed during the control phase. The success of the radiation control algorithm and current experiments in radiated power control represents a significant advance for steady-state divertor radiation and heat flux control on EAST for near-future long-pulse operation.

Tri-channel single-mode terahertz quantum cascade laser.

PubMed

Wang, Tao; Liu, Jun-Qi; Liu, Feng-Qi; Wang, Li-Jun; Zhang, Jin-Chuan; Wang, Zhan-Guo

2014-12-01

We report on a compact THz quantum cascade laser source emitting at, individually controllable, three different wavelengths (92.6, 93.9, and 95.1 μm). This multiwavelength laser array can be used as a prototype of the emission source of THz wavelength division multiplex (WDM) wireless communication system. The source consists of three tapered single-mode distributed feedback (DFB) terahertz quantum cascade lasers fabricated monolithically on a single chip. All array elements feature longitudinal as well as lateral single-mode in the entire injection range. The peak output powers of individual lasers are 42, 73, and 37 mW at 10 K, respectively.

Investigation of the long-lived saturated internal mode and its control on the HL-2A tokamak

NASA Astrophysics Data System (ADS)

Wei, Deng; Yi, Liu; Xian-Qu, Wang; Wei, Chen; Yun-Bo, Dong; Ohdachi, S.; Xiao-Quan, Ji; Yong, Shen; Jian-Yong, Cao; Jun, Zhou; Bei-Bing, Feng; Yong-Gao, Li; Xian-Li, Huang; Jin-Ming, Gao; Xiao-Yu, Han; Mei, Huang; Xiao-Gang, Wang

2014-01-01

HL-2A plasmas heated by neutral beam injection (NBI) regularly exhibit n = 1 long-lived saturated magnetohydrodynamic instabilities. A reduction in the electron density and plasma stored energy and an increase in fast ion losses are usually observed in the presence of such perturbations. The observed long-lived saturated internal mode (LLM) occurs when the safety factor profile has a weak shear in a broad range of the plasma centre with qmin around unity. It is found that the ideal interchange mode can become marginally stable due to the weak magnetic shear reaching a critical value. The LLM, due to its pressure-driven feature, is destabilized by the strong interaction with fast ions in the low-shear region during the NBI. Furthermore, for the first time it is clearly observed that the LLMs can be suppressed by electron cyclotron resonant heating (ECRH), or by supersonic molecular beam injection in HL-2A plasmas. Low-n sidebands observed during the LLM are also suppressed by increasing the ECRH power. The control of LLMs is due to the change in the magnetic shear or in the pressure profile induced by the local heating or fuelling.

Observations of the effect of lower hybrid waves on ELM behaviour in EAST

NASA Astrophysics Data System (ADS)

Chen, R.; Xu, G. S.; Liang, Y.; Wang, H. Q.; Zhou, C.; Liu, A. D.; Wang, L.; Qian, J. P.; Gan, K. F.; Yang, J. H.; Duan, Y. M.; Li, Y. L.; Ding, S. Y.; Wu, X. Q.; Yan, N.; Chen, L.; Shao, L. M.; Zhang, W.; Hu, G. H.; Zhao, N.; Liu, S. C.; Kong, D. F.; Gong, X. Z.

2015-03-01

Dedicated experiments focusing on the influence of lower hybrid waves (LHWs) on edge-localized modes (ELMs) were first performed during the 2012 experimental campaign of EAST, via modulating the input power of LHWs in the high-confinement-mode (H-mode) plasma mainly sustained by ion cyclotron resonant heating. Natural ELMs are effectively mitigated (ELM frequency increases, while its intensity decreases dramatically) as the LHW is applied, observed over a fairly wide range of plasma current or edge safety factor. By scanning the modulation frequency (fm) of LHW injected power in a target plasma dominated by the so-called small ELMs, we conclude that large ELMs with markedly larger amplitudes and lower frequencies are reproduced at low modulation frequencies (fm < 100 Hz). Analysis of the evolution of edge extreme ultraviolet radiation signals further indicates that plasma fluctuations at the pedestal region indistinctively respond to rapid modulation (fm ⩾ 100 Hz) of LHW injected power. This is proposed as the mechanism responsible for the observed fm dependence of the mitigation effect induced by LHWs on large ELMs. In addition, a critical threshold of LHW input power PLHW is estimated as PLHWthr≃800 kW , beyond which the impact of applied LHWs on ELM behaviours can be achieved. Finally, Langmuir probe measurements suggest that, rather than the concentration of free energy into a narrowband quasi-coherent precursor commonly observed growing until the ELM crash, the continuous development of broadband turbulence during the ELM-absent phase with the application of LHWs might contribute to the avoidance of ELM crashes. These results present new insights into existing experiments, and also provide some foundations and references for the next-step research about exploring in more depth and improving this new attractive method to effectively control the ELM-induced very large transient heat and particle flux.

A pulsated weak-resonant-cavity laser diode with transient wavelength scanning and tracking for injection-locked RZ transmission.

PubMed

Lin, Gong-Ru; Chi, Yu-Chieh; Liao, Yu-Sheng; Kuo, Hao-Chung; Liao, Zhi-Wang; Wang, Hai-Lin; Lin, Gong-Cheng

2012-06-18

By spectrally slicing a single longitudinal-mode from a master weak-resonant-cavity Fabry-Perot laser diode with transient wavelength scanning and tracking functions, the broadened self-injection-locking of a slave weak-resonant-cavity Fabry-Perot laser diode is demonstrated to achieve bi-directional transmission in a 200-GHz array-waveguide-grating channelized dense-wavelength-division-multiplexing passive optical network system. Both the down- and up-stream slave weak-resonant-cavity Fabry-Perot laser diodes are non-return-to-zero modulated below threshold and coherently injection-locked to deliver the pulsed carrier for 25-km bi-directional 2.5 Gbits/s return-to-zero transmission. The master weak-resonant-cavity Fabry-Perot laser diode is gain-switched at near threshold condition and delivers an optical coherent pulse-train with its mode linewidth broadened from 0.2 to 0.8 nm by transient wavelength scanning, which facilitates the broadband injection-locking of the slave weak-resonant-cavity Fabry-Perot laser diodes with a threshold current reducing by 10 mA. Such a transient wavelength scanning induced spectral broadening greatly releases the limitation on wavelength injection-locking range required for the slave weak-resonant-cavity Fabry-Perot laser diode. The theoretical modeling and numerical simulation on the wavelength scanning and tracking effects of the master and slave weak-resonant-cavity Fabry-Perot laser diodes are performed. The receiving power sensitivity for back-to-back transmission at bit-error-rate <10(-10) is -25.6 dBm, and the power penalty added after 25-km transmission is less than 2 dB for all 16 channels.

Reliability modelling and analysis of thermal MEMS

NASA Astrophysics Data System (ADS)

Muratet, Sylvaine; Lavu, Srikanth; Fourniols, Jean-Yves; Bell, George; Desmulliez, Marc P. Y.

2006-04-01

This paper presents a MEMS reliability study methodology based on the novel concept of 'virtual prototyping'. This methodology can be used for the development of reliable sensors or actuators and also to characterize their behaviour in specific use conditions and applications. The methodology is demonstrated on the U-shaped micro electro thermal actuator used as test vehicle. To demonstrate this approach, a 'virtual prototype' has been developed with the modeling tools MatLab and VHDL-AMS. A best practice FMEA (Failure Mode and Effect Analysis) is applied on the thermal MEMS to investigate and assess the failure mechanisms. Reliability study is performed by injecting the identified defaults into the 'virtual prototype'. The reliability characterization methodology predicts the evolution of the behavior of these MEMS as a function of the number of cycles of operation and specific operational conditions.

HIV AND HCV COINFECTION: PREVALENCE, ASSOCIATED FACTORS AND GENOTYPE CHARACTERIZATION IN THE MIDWEST REGION OF BRAZIL

PubMed Central

Freitas, Solange Zacalusni; Teles, Sheila Araújo; Lorenzo, Paulo Cesar; Puga, Marco Antonio Moreira; Tanaka, Tayana Serpa Ortiz; Thomaz, Danilo Yamamoto; Martins, Regina Maria Bringel; Druzian, Angelita Fernandes; Lindenberg, Andréa Siqueira Campos; Torres, Marina Sawada; Pereira, Sérgio A.; Villar, Livia Melo; Lampe, Elisabete; Motta-Castro, Ana Rita Coimbra

2014-01-01

A cross-sectional study on prevalence, associated factors and genotype distribution of HCV infection was conducted among 848 HIV-infected patients recruited at reference centers in the Midwest Region of Brazil. The prevalence rate of HIV-HCV coinfection was 6.9% (95% CI: 5.2 to 8.6). In multivariable analysis, increasing age, use of illicit drugs (injection and non-injection), a history of blood transfusion before 1994, and the absence of a steady partnership were significant independent associated factors for HIV-HCV coinfection. The phylogenetic analysis based on the NS5B region revealed the presence of two major circulating genotypes of HCV: genotypes 1 (58.3%) and 3 (41.7%). The prevalence of HIV-HCV coinfection was lower than those reported in studies conducted with HIV-infected patients in different regions of Brazil, due to the fact that illicit drug use is not a frequent mode of HIV transmission in this region of Brazil. Serologic screening of HIV-patients for HCV before initiating antiretroviral treatment, a comprehensive identification of associated factors, and the implementation of effective harm reduction programs are highly recommended to provide useful information for treatment and to prevent HCV coinfection in these patients. PMID:25351547

Design for dependability: A simulation-based approach. Ph.D. Thesis, 1993

NASA Technical Reports Server (NTRS)

Goswami, Kumar K.

1994-01-01

This research addresses issues in simulation-based system level dependability analysis of fault-tolerant computer systems. The issues and difficulties of providing a general simulation-based approach for system level analysis are discussed and a methodology that address and tackle these issues is presented. The proposed methodology is designed to permit the study of a wide variety of architectures under various fault conditions. It permits detailed functional modeling of architectural features such as sparing policies, repair schemes, routing algorithms as well as other fault-tolerant mechanisms, and it allows the execution of actual application software. One key benefit of this approach is that the behavior of a system under faults does not have to be pre-defined as it is normally done. Instead, a system can be simulated in detail and injected with faults to determine its failure modes. The thesis describes how object-oriented design is used to incorporate this methodology into a general purpose design and fault injection package called DEPEND. A software model is presented that uses abstractions of application programs to study the behavior and effect of software on hardware faults in the early design stage when actual code is not available. Finally, an acceleration technique that combines hierarchical simulation, time acceleration algorithms and hybrid simulation to reduce simulation time is introduced.

Determination of tributyltin in environmental water matrices using stir bar sorptive extraction with in-situ derivatisation and large volume injection-gas chromatography-mass spectrometry.

PubMed

Neng, N R; Santalla, R P; Nogueira, J M F

2014-08-01

Stir bar sorptive extraction with in-situ derivatization using sodium tetrahydridoborate (NaBH4) followed by liquid desorption and large volume injection-gas chromatography-mass spectrometry detection under the selected ion monitoring mode (SBSE(NaBH4)in-situ-LD/LVI-GC-MS(SIM)) was successfully developed for the determination of tributyltin (TBT) in environmental water matrices. NaBH4 proved to be an effective and easy in-situ speciation agent for TBT in aqueous media, allowing the formation of adducts with enough stability and suitable polarity for SBSE analysis. Assays performed on water samples spiked at the 10.0μg/L, yielded convenient recoveries (68.2±3.0%), showed good accuracy, suitable precision (RSD<9.0%), low detection limits (23ng/L) and excellent linear dynamic range (r(2)=0.9999) from 0.1 to 170.0µg/L, under optimized experimental conditions. By using the standard addition method, the application of the present methodology to real surface water samples allowed very good performance at the trace level. The proposed methodology proved to be a feasible alternative for routine quality control analysis, easy to implement, reliable and sensitive to monitor TBT in environmental water matrices. Copyright © 2014 Elsevier B.V. All rights reserved.

Single nanowire green InGaN/GaN light emitting diodes

NASA Astrophysics Data System (ADS)

Zhang, Guogang; Li, Ziyuan; Yuan, Xiaoming; Wang, Fan; Fu, Lan; Zhuang, Zhe; Ren, Fang-Fang; Liu, Bin; Zhang, Rong; Tan, Hark Hoe; Jagadish, Chennupati

2016-10-01

Single nanowire (NW) green InGaN/GaN light-emitting diodes (LEDs) were fabricated by top-down etching technology. The electroluminescence (EL) peak wavelength remains approximately constant with an increasing injection current in contrast to a standard planar LED, which suggests that the quantum-confined Stark effect is significantly reduced in the single NW device. The strain relaxation mechanism is studied in the single NW LED using Raman scattering analysis. As compared to its planar counterpart, the EL peak of the NW LED shows a redshift, due to electric field redistribution as a result of changes in the cavity mode pattern after metallization. Our method has important implication for single NW optoelectronic device applications.

A dilute-and-shoot flow-injection tandem mass spectrometry method for quantification of phenobarbital in urine.

PubMed

Alagandula, Ravali; Zhou, Xiang; Guo, Baochuan

2017-01-15

Liquid chromatography/tandem mass spectrometry (LC/MS/MS) is the gold standard of urine drug testing. However, current LC-based methods are time consuming, limiting the throughput of MS-based testing and increasing the cost. This is particularly problematic for quantification of drugs such as phenobarbital, which is often analyzed in a separate run because they must be negatively ionized. This study examined the feasibility of using a dilute-and-shoot flow-injection method without LC separation to quantify drugs with phenobarbital as a model system. Briefly, a urine sample containing phenobarbital was first diluted by 10 times, followed by flow injection of the diluted sample to mass spectrometer. Quantification and detection of phenobarbital were achieved by an electrospray negative ionization MS/MS system operated in the multiple reaction monitoring (MRM) mode with the stable-isotope-labeled drug as internal standard. The dilute-and-shoot flow-injection method developed was linear with a dynamic range of 50-2000 ng/mL of phenobarbital and correlation coefficient > 0.9996. The coefficients of variation and relative errors for intra- and inter-assays at four quality control (QC) levels (50, 125, 445 and 1600 ng/mL) were 3.0% and 5.0%, respectively. The total run time to quantify one sample was 2 min, and the sensitivity and specificity of the method did not deteriorate even after 1200 consecutive injections. Our method can accurately and robustly quantify phenobarbital in urine without LC separation. Because of its 2 min run time, the method can process 720 samples per day. This feasibility study shows that the dilute-and-shoot flow-injection method can be a general way for fast analysis of drugs in urine. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Numerical Optimisation in Non Reacting Conditions of the Injector Geometry for a Continuous Detonation Wave Rocket Engine

NASA Astrophysics Data System (ADS)

Gaillard, T.; Davidenko, D.; Dupoirieux, F.

2015-06-01

The paper presents the methodology and the results of a numerical study, which is aimed at the investigation and optimisation of different means of fuel and oxidizer injection adapted to rocket engines operating in the rotating detonation mode. As the simulations are achieved at the local scale of a single injection element, only one periodic pattern of the whole geometry can be calculated so that the travelling detonation waves and the associated chemical reactions can not be taken into account. Here, separate injection of fuel and oxidizer is considered because premixed injection is handicapped by the risk of upstream propagation of the detonation wave. Different associations of geometrical periodicity and symmetry are investigated for the injection elements distributed over the injector head. To analyse the injection and mixing processes, a nonreacting 3D flow is simulated using the LES approach. Performance of the studied configurations is analysed using the results on instantaneous and mean flowfields as well as by comparing the mixing efficiency and the total pressure recovery evaluated for different configurations.

Progress to a Gallium-Arsenide Deep-Center Laser

PubMed Central

Pan, Janet L.

2009-01-01

Although photoluminescence from gallium-arsenide (GaAs) deep-centers was first observed in the 1960s, semiconductor lasers have always utilized conduction-to-valence-band transitions. Here we review recent materials studies leading to the first GaAs deep-center laser. First, we summarize well-known properties: nature of deep-center complexes, Franck-Condon effect, photoluminescence. Second, we describe our recent work: insensitivity of photoluminescence with heating, striking differences between electroluminescence and photoluminescence, correlation between transitions to deep-states and absence of bandgap-emission. Room-temperature stimulated-emission from GaAs deep-centers was observed at low electrical injection, and could be tuned from the bandgap to half-the-bandgap (900–1,600 nm) by changing the electrical injection. The first GaAs deep-center laser was demonstrated with electrical injection, and exhibited a threshold of less than 27 mA/cm2 in continuous-wave mode at room temperature at the important 1.54 μm fiber-optic wavelength. This small injection for laser action was explained by fast depopulation of the lower state of the optical transition (fast capture of free holes onto deep-centers), which maintains the population inversion. The evidence for laser action included: superlinear L-I curve, quasi-Fermi level separations satisfying Bernard-Duraffourg’s criterion, optical gains larger than known significant losses, clamping of the optical-emission from lossy modes unable to reach laser action, pinning of the population distribution during laser action.

A time-cost augmented economic evaluation of oral deferasirox versus infusional deferoxamine [corrected] for patients with iron overload in South Korea.

PubMed

Kim, Jinhyun; Kim, Younhee

2009-01-01

This study aims to conduct an economic evaluation of oral deferasirox (DSX) compared with infusional deferoxamine (DFO) in patients with transfusional iron overload. Depending on the methods for measuring time-cost and convenience associated with the mode of administration, either cost-utility analysis or cost-effectiveness analysis was undertaken. The difference in compliance rate between DSX and DFO was applied. Although the drug cost of DSX was US$124,070 higher than that of DFO (US$96,039 vs. US$220,199), all other costs were lower in patients with DSX than in patients with DFO. In the cost-utility analysis, DSX resulted in US$3197 savings with a gain of 2.63 quality-adjusted life-years per patient. The result of the cost-effectiveness analysis also showed that DSX dominated DFO. With a considerable improvement in convenience and injection time rather than efficacy, DSX is considered as a dominant therapy for patients with iron overload.

Resonantly Enhanced Betatron Hard X-rays from Ionization Injected Electrons in a Laser Plasma Accelerator

PubMed Central

Huang, K.; Li, Y. F.; Li, D. Z.; Chen, L. M.; Tao, M. Z.; Ma, Y.; Zhao, J. R.; Li, M. H.; Chen, M.; Mirzaie, M.; Hafz, N.; Sokollik, T.; Sheng, Z. M.; Zhang, J.

2016-01-01

Ultrafast betatron x-ray emission from electron oscillations in laser wakefield acceleration (LWFA) has been widely investigated as a promising source. Betatron x-rays are usually produced via self-injected electron beams, which are not controllable and are not optimized for x-ray yields. Here, we present a new method for bright hard x-ray emission via ionization injection from the K-shell electrons of nitrogen into the accelerating bucket. A total photon yield of 8 × 108/shot and 108 photons with energy greater than 110 keV is obtained. The yield is 10 times higher than that achieved with self-injection mode in helium under similar laser parameters. The simulation suggests that ionization-injected electrons are quickly accelerated to the driving laser region and are subsequently driven into betatron resonance. The present scheme enables the single-stage betatron radiation from LWFA to be extended to bright γ-ray radiation, which is beyond the capability of 3rd generation synchrotrons. PMID:27273170

Injection dynamics of gelled propellants

NASA Astrophysics Data System (ADS)

Yoon, Changjin

Gel propellants have been recognized as attractive candidates for future propulsion systems due to the reduced tendency to spill and the energy advantages over solid propellants. One of strong benefits emphasized in gel propellant applications is a throttling capability, but the accurate flow control is more complicated and difficult than with conventional Newtonian propellants because of the unique rheological behaviors of gels. This study is a computational effort directed to enhance understanding of the injector internal flow characteristics for gel propellants under rocket injection conditions. In simulations, the emphasized rheology is a shear-thinning which represents a viscosity decrease with increasing a shear rate. It is described by a generalized Newtonian fluid constitutive equation and Carreau-Yasuda model. Using this rheological model, two injection schemes are considered in the present study: axially-fed and cross-fed injection for single-element and multi-element impinging injectors, respectively. An axisymmetric model is developed to describe the axially-fed injector flows and fully three-dimensional model is utilized to simulate cross-fed injector flows. Under axially-fed injection conditions investigated, three distinct modes, an unsteady, steady, and hydraulic flip mode, are observed and mapped in terms of Reynolds number and orifice design. In an unsteady mode, quasi-periodic oscillations occur near the inlet lip leading mass pulsations and viscosity fluctuations at the orifice exit. This dynamic behavior is characterized using a time-averaged discharge coefficient, oscillation magnitude and frequency by a parametric study with respect to an orifice design, Reynolds number and rheology. As a result, orifice exit flows for gel propellants appear to be significantly influenced by a viscous damping and flow resistance due to a shear thinning behavior and these are observed in each factors considered. Under conditions driven by a manifold crossflow, unsteady and asymmetric flow structures are revealed as a series of vortices generated from the unstable vena contracta. Here, flows are characterized by an orifice design, manifold/core injection velocity ratio, Reynolds number and rheology. A significant decrease of discharge coefficients is noted with increasing the manifold flow. As the manifold crossflow increases, stronger friction losses are exerted on the leeward, and lead to larger hydraulic losses across the injector. In addition, calculations show that discharge coefficients decrease and the unsteadiness is mitigated as the viscosity increases by fluid rheology variations. A larger and more distinct horseshoe vortex is observed, and pulsation magnitude and viscosity fluctuations are mitigated with increasing viscosity. The oscillation frequency, however, remains unchanged even though the viscosity curves at the high shear rate are modified. All these observations confirm the conclusion that the role of viscous damping and flow resistance is more critical in cross-fed injection conditions than in axially-fed one.

Precipitated Fluxes of Radiation Belt Electrons via Injection of Whistler-Mode Waves

NASA Astrophysics Data System (ADS)

Kulkarni, P.; Inan, U. S.; Bell, T. F.

2005-12-01

Inan et al. (U.S. Inan et al., Controlled precipitation of radiation belt electrons, Journal of Geophysical Research-Space Physics, 108 (A5), 1186, doi: 10.1029/2002JA009580, 2003.) suggested that the lifetime of energetic (a few MeV) electrons in the inner radiation belts may be moderated by in situ injection of whistler mode waves at frequencies of a few kHz. We use the Stanford 2D VLF raytracing program (along with an accurate estimation of the path-integrated Landau damping based on data from the HYDRA instrument on the POLAR spacecraft) to determine the distribution of wave energy throughout the inner radiation belts as a function of injection point, wave frequency and injection wave normal angle. To determine the total wave power injected and its initial distribution in k-space (i.e., wave-normal angle), we apply the formulation of Wang and Bell ( T.N.C. Wang and T.F. Bell, Radiation resistance of a short dipole immersed in a cold magnetoionic medium, Radio Science, 4 (2), 167-177, February 1969) for an electric dipole antenna placed at a variety of locations throughout the inner radiation belts. For many wave frequencies and wave normal angles the results establish that most of the radiated power is concentrated in waves whose wave normals are located near the resonance cone. The combined use of the radiation pattern and ray-tracing including Landau damping allows us to make quantitative estimates of the magnetospheric distribution of wave power density for different source injection points. We use these results to estimate the number of individual space-based transmitters needed to significantly impact the lifetimes of energetic electrons in the inner radiation belts. Using the wave power distribution, we finally determine the energetic electron pitch angle scattering and the precipitated flux signatures that would be detected.

1.55-μm mode-locked quantum-dot lasers with 300 MHz frequency tuning range

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

Sadeev, T., E-mail: tagir@mailbox.tu-berlin.de; Arsenijević, D.; Bimberg, D.

2015-01-19

Passive mode-locking of two-section quantum-dot mode-locked lasers grown by metalorganic vapor phase epitaxy on InP is reported. 1250-μm long lasers exhibit a wide tuning range of 300 MHz around the fundamental mode-locking frequency of 33.48 GHz. The frequency tuning is achieved by varying the reverse bias of the saturable absorber from 0 to −2.2 V and the gain section current from 90 to 280 mA. 3 dB optical spectra width of 6–7 nm leads to ex-facet optical pulses with full-width half-maximum down to 3.7 ps. Single-section quantum-dot mode-locked lasers show 0.8 ps broad optical pulses after external fiber-based compression. Injection current tuning from 70 tomore » 300 mA leads to 30 MHz frequency tuning.« less

Resistive magnetohydrodynamics with toroidal rotation in toroidal plasmas

NASA Astrophysics Data System (ADS)

Cao, Jintao; Cai, Huishan

2018-01-01

Toroidal rotation has always existed in tokamak plasmas, and its Mach number can reach unity during neutral beam injection. Toroidal rotation can affect plasma equilibrium and magnetohydrodynamic instabilities significantly. Based on linearized equations including the toroidal rotation effect, the toroidal model derived by Glasser et al. [Phys. Fluids 18, 875 (1975)] is extended to include this effect, and a set of resistive equations including the toroidal rotation effect in the axi-symmetry toroidal geometry is derived. Based on these derived equations, the effect of toroidal rotation on tearing modes is considered, and the growth rate of tearing modes is obtained analytically. It is shown that the effect of toroidal rotation on tearing modes depends on both the direction of toroidal rotation flow and the sign of toroidal rotation flow shear. When they have the same sign, they play a role in stabilizing tearing modes, while when they have opposite signs, they have a destabilizing effect on tearing modes.

1.5 W high efficiency and tunable single-longitudinal-mode Ho:YLF ring laser based on Faraday effect.

PubMed

Wu, Jing; Ju, Youlun; Dai, Tongyu; Yao, Baoquan; Wang, Yuezhu

2017-10-30

We demonstrated an efficient and tunable single-longitudinal-mode Ho:YLF ring laser based on Faraday effect for application to measure atmospheric carbon dioxide (CO 2 ). Single-longitudinal-mode power at 2051.65 nm achieved 528 mW with the slope efficiency of 39.5% and the M 2 factor of 1.07, and the tunable range of about 178 GHz was obtained by inserting a Fabry-Perot (F-P) etalon with the thickness of 0.5 mm. In addition, the maximum single-longitudinal-mode power reached 1.5 W with the injected power of 528 mW at 2051.65 nm by master oscillator power amplifier (MOPA) technique. High efficiency and tunable single-longitudinal-mode based on Faraday effect around 2 μm has not been reported yet to the best of our knowledge.

Streak instability and generation of hairpin-vortices by a slotted jet in channel crossflow: Experiments and linear stability analysis

NASA Astrophysics Data System (ADS)

Philip, Jimmy; Karp, Michael; Cohen, Jacob

2016-01-01

Streaks and hairpin-vortices are experimentally generated in a laminar plane Poiseuille crossflow by injecting a continuous jet through a streamwise slot normal to the crossflow, with air as the working media. Small disturbances form stable streaks, however, higher disturbances cause the formation of streaks which undergo instability leading to the generation of hairpin vortices. Particular emphasis is placed on the flow conditions close to the generation of hairpin-vortices. Measurements are carried out in the cases of natural and phase-locked disturbance employing smoke visualisation, particle image velocimetry, and hot-wire anemometry, which include, the dominant frequency, wavelength, and the disturbance shape (or eigenfunctions) associated with the coherent part of the velocity field. A linear stability analysis for both one- and two-dimensional base-flows is carried out to understand the mechanism of instability and good agreement of wavelength and eigenfunctions are obtained when compared to the experimental data, and a slight under-prediction of the growth-rates by the linear stability analysis consistent with the final nonlinear stages in transitional flows. Furthermore, an energy analysis for both the temporal and spatial stability analysis revels the dominance of the symmetric varicose mode, again, in agreement with the experiments, which is found to be governed by the balance of the wallnormal shear and dissipative effects rather than the spanwise shear. In all cases the anti-symmetric sinuous modes governed by the spanwise shear are found to be damped both in analysis and in our experiments.