Sample records for term pulse mode

  1. Single mode pulsed dye laser oscillator

    DOE Patents [OSTI]

    Hackel, R.P.

    1992-11-24T23:59:59.000Z

    A single mode pulsed dye laser oscillator is disclosed. The dye laser oscillator provides for improved power efficiency by reducing the physical dimensions of the overall laser cavity, which improves frequency selection capability. 6 figs.

  2. 1966 JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 15, NO. 10, OCTOBER 1997 Mode Conversion of Ultrafast Pulses by Grating

    E-Print Network [OSTI]

    Ziolkowski, Richard W.

    conversion of an ultrafast, ultrawide-bandwidth optical pulse propagating in a layered di- electric waveguide for an ultrafast six-cycle optical pulse over that achieved with standard uniform grating convertors. Index Terms--Dielectric waveguides, FDTD, mode conversion, mode extraction, numerical modeling, ultrafast optical pulses. I

  3. Polymeric electrochemical element for adaptive networks: Pulse mode

    SciTech Connect (OSTI)

    Smerieri, Anteo [Department of Physics, University of Parma, Viale Usberti 7A, Parma (Puerto Rico) 43100 (Italy); Berzina, Tatiana [CRS SOFT CNR-INFM, Rome 00185 (Italy); Erokhin, Victor; Fontana, M. P. [Department of Physics, University of Parma, Viale Usberti 7A, Parma (Puerto Rico) 43100 (Italy); CRS SOFT CNR-INFM, Rome 00185 (Italy)

    2008-12-01T23:59:59.000Z

    An electrochemically controlled polymeric heterojunction working as a memristor, i.e., having memory properties, was investigated in pulse mode, mimicking synaptic behavior of signal transmission in biological systems. Influence of parameters such as pulse duration, interval between pulses, and value of potential base level was analyzed. Learning capabilities were shown to be reversible and repeatable for both potentiation and inhibition of signal transmission. The adaptive behavior of the element was investigated and was shown to be more efficient than the dc mode.

  4. March 15, 2000 / Vol. 25, No. 6 / OPTICS LETTERS 423 Generation of 90-fs pulses from a mode-locked diode-pumped

    E-Print Network [OSTI]

    Boyer, Edmond

    with a crystalline host. This laser is mode locked with a high-finesse semiconductor saturable-absorber mirror with the capability to bridge the gap in terms of pulse dura- tion, on the one hand, and emission cross sections

  5. Mode-Locked Fibre Lasers with High-Energy Pulses

    E-Print Network [OSTI]

    Turitsyn, Sergei K.

    , including generation of ultra-short and high-energy pulses. Since the invention of the laser researchers, technological, medical, and other applications. High energies and ultra-short pulse durations are both resonators. In addition, the path to high-energy ultra-short pulses is, typically, further complicated

  6. Control and generation of localized pulses in passively mode-locked semiconductor lasers

    E-Print Network [OSTI]

    Marconi, M; Camelin, P; Chaparro, D; Balle, S; Giudici, M

    2015-01-01T23:59:59.000Z

    We show experimentally and theoretically that localized pulses can be generated from an electrically biased $200\\,\\mu$m multi-transverse mode Vertical-Cavity Surface-Emitting Laser. The device is passively mode-locked using optical feedback from a distant Resonant Saturable Absorber Mirror and it is operated below threshold. We observe multistability between the off solution and a large variety of pulsating solutions with different number and arrangements of pulses per round-trip, thus indicating that the mode-locked pulses are localized, i.e. mutually independent. We show that a modulation of the bias current allows controlling the number of the pulses travelling within the cavity, thus suggesting that our system can be operated as an arbitrary pattern generator of 10 ps pulses and 1 W peak power.

  7. Modes in a pulse-modulated radio-frequency dielectric-barrier glow discharge

    SciTech Connect (OSTI)

    Shi, J. J.; Zhang, J.; Qiu, G. [College of Science, Donghua University, Shanghai 201620 (China); Walsh, J. L.; Kong, M. G. [Department of Electronic and Electrical Engineering, Loughborough University, Loughborough, Leicestershire LE11 3TU (United Kingdom)

    2008-07-28T23:59:59.000Z

    This letter reports an experimental study of a pulse-modulated radio-frequency dielectric-barrier discharge in atmospheric helium. By controlling the duty cycle at a modulation frequency of 10 and 100 kHz, the 13.56 MHz discharge is shown to operate in three different glow modes: the continuum mode, the discrete mode, and the transition mode. By investigating plasma ignition, residual electrons during power off are found to affect different glow modes. Duty cycle dependences of power density, gas temperature, optical emission intensities at 706 and 777 nm are used to capture clearly the characteristics of the three glow modes.

  8. Ultra-low repetition rate mode-locked fiber laser with high-energy pulses

    E-Print Network [OSTI]

    Kobtsev, Sergei M.

    to ultra-short record high-energy pulses out of laser oscillators," Phys. Lett. A 372, 3124­3128 (2008). 5Ultra-low repetition rate mode-locked fiber laser with high-energy pulses Sergey Kobtsev* , Sergey Kukarin, Yurii Fedotov Laser Systems Laboratory, Novosibirsk State University,Pirigova 2, Novosibirsk

  9. Flat-top pulse generation based on the combined action of active mode locking and nonlinear polarization rotation

    E-Print Network [OSTI]

    Wai, Ping-kong Alexander

    Flat-top pulse generation based on the combined action of active mode locking and nonlinear: A pulsewidth tunable 10 GHz flat-top pulse train is generated based on the combined action of active mode can be improved by using flat top clock pulses for the demultiplexing. Recently, there are reports

  10. Non-uniform spectral encoding of measured mode-locked laser pulses for performance enhancement of optical CDMA

    E-Print Network [OSTI]

    Kolner, Brian H.

    -flat spectra of realistic ultra-short optical pulse sources (e.g. a mode-locked laser), true orthogonality implements the encoding and decoding through all-optical pulse shaping of an ultra-short optical pulse. One capacity. 2. Theory For simplicity, we express the electrical field of the ultra-short pulse in time domain

  11. Optically induced mode conversion in graded-index fibers using ultra-short laser pulses

    E-Print Network [OSTI]

    Hellwig, Tim; Fallnich, Carsten

    2013-01-01T23:59:59.000Z

    We propose the use of graded-index few-mode fibers for mode-conversion by long-period gratings (LPG) transiently written by ultrashort laser pulses using the optical Kerr effect. The mode inter- action is studied by numerically solving the multi-mode coupled nonlinear Schroedinger equations. We present highly efficient conversion of the LP 01 - into the LP 11 -mode preserving the pulse shape in contrast to previous results in step-index fibers. Furthermore, mode conversion using different wavelengths for inducing and probing the LPG is shown. Due to the flat phase-matching curve of the examined modes in the graded-index fiber, mode-conversion can be observed for probe center wavelengths of 1100nm up to 1800nm with a write beam centered around 1030nm. Therefore, a complete separation of the probe from the write beam should be possible as well as the application of optically induced guided mode conversion for all optical modulation across a broad wavelength range.

  12. Noise characterization of a pulse train generated by actively mode-locked lasers

    SciTech Connect (OSTI)

    Eliyahu, D.; Salvatore, R.A.; Yariv, A. [California Institute of Technology, Mail Stop 128-95, Pasadena, California 91125 (United States)

    1996-07-01T23:59:59.000Z

    We analyze the entire power spectrum of pulse trains generated by a continuously operating actively mode-locked laser in the presence of noise. We consider the effect of amplitude, pulse-shape, and timing-jitter fluctuations that are characterized by stationary processes. Effects of correlations between different parameters of these fluctuations are studied also. The nonstationary timing-jitter fluctuations of passively mode-locked lasers and their influence on the power spectrum is discussed as well. {copyright} {ital 1996 Optical Society of America.}

  13. Birefringence-Induced Trains of High-Rate Pulses in a Mode-Locked Fiber Laser

    E-Print Network [OSTI]

    Zadok, Avinoam

    , August 2009 Avi Zadok Jacob Sendowski Amnon Yariv, Life Fellow, IEEE DOI: 10.1109/JPHOT.2009.2027441 1943-Rate Pulses in a Mode-Locked Fiber Laser Avi Zadok, Jacob Sendowski, and Amnon Yariv, Life Fellow, IEEE published Online July 7, 2009. Current version published July 24, 2009. The work of A. Zadok is supported

  14. Few-cycle pulses from a graphene mode-locked all-fiber laser

    E-Print Network [OSTI]

    Purdie, D; Wittwer, V J; Jiang, Z; Bonacchini, G; Torrisi, F; Milana, S; Lidorikis, E; Ferrari, A C

    2015-01-01T23:59:59.000Z

    We combine a graphene mode-locked oscillator with an external compressor and achieve~29fs pulses with~52mW average power. This is a simple, low-cost, and robust setup, entirely fiber based, with no free-space optics, for applications requiring high temporal resolution.

  15. Pulse shortening, spatial mode cleaning, and intense terahertz generation by filamentation in xenon

    SciTech Connect (OSTI)

    Akturk, Selcuk; D'Amico, Ciro; Franco, Michel; Couairon, Arnaud; Mysyrowicz, Andre [Laboratoire d'Optique Appliquee, Ecole Nationale Superieure des Techniques Avancees-Ecole Polytechnique, CNRS UMR 7639 F-91761 Palaiseau Cedex, France and Centre de Physique Theorique, CNRS UMR 7644, Ecole Polytechnique, F-91128 Palaiseau Cedex (France)

    2007-12-15T23:59:59.000Z

    We performed a comprehensive study of filamentation in xenon. Due to its high nonlinear refraction index, but relatively low ionization potential, xenon can support filamentation at peak powers lower than in air. In our experiments, we studied pulse shortening, spatial mode cleaning, and generation of terahertz radiation. We observed that in xenon, self-compression is easily obtainable and terahertz radiation generation efficiency is significantly stronger as compared to air.

  16. Ultra-short-pulsed and highly-efficient diode-pumped Yb:SYS mode-locked oscillators

    E-Print Network [OSTI]

    Boyer, Edmond

    "Laser crystals for the production of ultra-short laser pulses," Ann. Chim. Mat. 28, 47-72 (2003). 3. CUltra-short-pulsed and highly-efficient diode- pumped Yb:SYS mode-locked oscillators Frédéric Druon) 1 69 35 88 07, frederic.druon@iota.u-psud.fr http://www.elsa-laser.com Abstract: We report

  17. Pulsed Mode Operation and Longitudinal Parameter Measurement of the Rossendorf SRF Gun

    E-Print Network [OSTI]

    Teichert, J; Buettig, H; Justus, M; Lehnert, U; Michel, P; Schamlott, A; Schneider, Ch; Schurig, R; Xiang, R; Klemz, G; Kamps, T; Rudolph, J; Schenk, M; Will, I

    2011-01-01T23:59:59.000Z

    The Rossendorf SRF gun with a 3½ cell cavity has been operated since 2007. It has produced CW beam with the electron energy of 3 MeV and the average current up to 16 ?A. The electron beam of the gun has been successfully injected into the ELBE superconducting linac since 2010. The Nb cavity has shown constant quality during the operation and for the Cs2Te photocathode life time of months could be obtained. Recently the gun started to run in the pulsed mode with higher gradient. The longitudinal Parameters have been measured in this mode. The dark current arose from the high gradient is studied. The main field emission source has been found to be the half cell. In this paper the new status of the SRF gun will be presented, and the latest results of the beam experiments will be discussed.

  18. Wavelength tunable source of subpicosecond pulses from CW passively mode-locked two-section multiple-quantum-well laser

    SciTech Connect (OSTI)

    Salvatore, R.A.; Schrans, T.; Yariv, A. (California Inst. of Tech., Pasadena, CA (United States). Dept. of Applied Physics)

    1993-07-01T23:59:59.000Z

    A wavelength tunable passively mode-locked semi-conductor laser source of subpicosecond pulses is demonstrated. The system includes a two-section multiple-quantum-well laser which is coupled to an external grating for tuning and is followed by an external grating pair for pulse compression. A tuning range of 16 nm around 846 nm is obtained, resulting in compressed pulse widths as short as 260 fs and pulse widths shorter than 600 fs for all wavelength values within this tuning range. Time bandwidth products are one to two times the transform limit.

  19. Long-term stable timing distribution of an ultrafast optical pulse train over multiple fiber links with polarization maintaining output

    E-Print Network [OSTI]

    Cox, Jonathan A.

    The distribution of an ultrafast optical pulse train over multiple fiber links with long-term stable timing precision within 2 femtoseconds rms is accomplished by integrating a polarization maintaining output with 300 meter ...

  20. Numerical and simulation study of terahertz radiation generation by laser pulses propagating in the extraordinary mode in magnetized plasma

    SciTech Connect (OSTI)

    Jha, Pallavi; Kumar Verma, Nirmal [Department of Physics, University of Lucknow, Lucknow-226007 (India)

    2014-06-15T23:59:59.000Z

    A one-dimensional numerical model for studying terahertz radiation generation by intense laser pulses propagating, in the extraordinary mode, through magnetized plasma has been presented. The direction of the static external magnetic field is perpendicular to the polarization as well as propagation direction of the laser pulse. A transverse electromagnetic wave with frequency in the terahertz range is generated due to the presence of the magnetic field. Further, two-dimensional simulations using XOOPIC code show that the THz fields generated in plasma are transmitted into vacuum. The fields obtained via simulation study are found to be compatible with those obtained from the numerical model.

  1. Abnormal electron-heating mode and formation of secondary-energetic electrons in pulsed microwave-frequency atmospheric microplasmas

    SciTech Connect (OSTI)

    Kwon, H. C. [Department of Electrical Engineering, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of) [Department of Electrical Engineering, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Research and Development Division, SK Hynix Semiconductor Inc., Icheon 467-701 (Korea, Republic of); Jung, S. Y. [Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750 (Korea, Republic of)] [Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750 (Korea, Republic of); Kim, H. Y.; Won, I. H.; Lee, J. K., E-mail: jkl@postech.ac.kr [Department of Electrical Engineering, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of)

    2014-03-15T23:59:59.000Z

    The formation of secondary energetic electrons induced by an abnormal electron-heating mode in pulsed microwave-frequency atmospheric microplasmas was investigated using particle-in-cell simulation. We found that additional high electron heating only occurs during the first period of the ignition phase after the start of a second pulse at sub-millimeter dimensions. During this period, the electrons are unable to follow the abruptly retreating sheath through diffusion alone. Thus, a self-consistent electric field is induced to drive the electrons toward the electrode. These behaviors result in an abnormal electron-heating mode that produces high-energy electrons at the electrode with energies greater than 50?eV.

  2. NO{sub x} and CO emissions from a pulse combustor operating in a lean premixed mode

    SciTech Connect (OSTI)

    Keller, J.O.; Bramlette, T.T.; Barr, P.K.; Alvarez, J.

    1993-04-01T23:59:59.000Z

    Emission levels below 5.0 ppM NO{sub x}, with corresponding levels of 75 ppM CO (corrected to 3% O{sub 2}), were achieved in a pulse combustor operating in a lean premixed mode. Both NO{sub x} and CO concentrations were invariant with the total mass flow rate, but NO{sub x} and CO concentrations did vary with the rate of microscopic mixing.

  3. Tools for quantum optics : pulsed polarization-maintaining Er-doped fiber laser and spatial mode manipulation in spontaneous parametric downconversion

    E-Print Network [OSTI]

    Venkatraman, Dheera

    2007-01-01T23:59:59.000Z

    Two separate projects were undertaken to improve technology for entangled photon sources, useful for quantum optics. In one project, a pulsed, mode-locked erbium-doped fiber laser, designed to be used as a seed laser for ...

  4. Gigahertz repetition rate, sub-femtosecond timing jitter optical pulse train directly generated from a mode-locked Yb:KYW laser

    E-Print Network [OSTI]

    Yang, Heewon; Shin, Junho; Kim, Chur; Choi, Sun Young; Kim, Guang-Hoon; Rotermund, Fabian; Kim, Jungwon

    2014-01-01T23:59:59.000Z

    We show that a 1.13-GHz repetition rate optical pulse train with 0.70 fs high-frequency timing jitter (integration bandwidth of 17.5 kHz - 10 MHz, where the measurement instrument-limited noise floor contributes 0.41 fs in 10 MHz bandwidth) can be directly generated from a free-running, single-mode diode-pumped Yb:KYW laser mode-locked by single-walled carbon nanotube (SWCNT)-coated mirrors. To our knowledge, this is the lowest timing jitter optical pulse train with the GHz repetition rate ever measured. If this pulse train is used for direct sampling of 565-MHz signals (Nyquist frequency of the pulse train), the demonstrated jitter level corresponds to the projected effective-number-of-bit (ENOB) of 17.8, which is much higher than the thermal noise limit of 50-ohm load resistance (~14 bits).

  5. Sliding Mode Pulsed Averaging IC Drivers for High Brightness Light Emitting Diodes

    SciTech Connect (OSTI)

    Dr. Anatoly Shteynberg, PhD

    2006-08-17T23:59:59.000Z

    This project developed new Light Emitting Diode (LED) driver ICs associated with specific (uniquely operated) switching power supplies that optimize performance for High Brightness LEDs (HB-LEDs). The drivers utilize a digital control core with a newly developed nonlinear, hysteretic/sliding mode controller with mixed-signal processing. The drivers are flexible enough to allow both traditional microprocessor interface as well as other options such as “on the fly” adjustment of color and brightness. Some other unique features of the newly developed drivers include • AC Power Factor Correction; • High power efficiency; • Substantially fewer external components should be required, leading to substantial reduction of Bill of Materials (BOM). Thus, the LED drivers developed in this research : optimize LED performance by increasing power efficiency and power factor. Perhaps more remarkably, the LED drivers provide this improved performance at substantially reduced costs compared to the present LED power electronic driver circuits. Since one of the barriers to market penetration for HB-LEDs (in particular “white” light LEDs) is cost/lumen, this research makes important contributions in helping the advancement of SSL consumer acceptance and usage.

  6. A Description of ELM-Free H-modes in Terms of a Neoclassical Edge Barrier and a ‘Mixed’ Model for Energy and Particle Transport

    E-Print Network [OSTI]

    A Description of ELM-Free H-modes in Terms of a Neoclassical Edge Barrier and a ‘Mixed’ Model for Energy and Particle Transport

  7. LONG-TERM PERFORMANCE OF SOLID OXIDE STACKS WITH ELECTRODE-SUPPORTED CELLS OPERATING IN THE STEAM ELECTROLYSIS MODE

    SciTech Connect (OSTI)

    J. E. O'Brien; R. C. O'Brien; X. Zhang; G. Tao; B. J. Butler

    2011-11-01T23:59:59.000Z

    Performance characterization and durability testing have been completed on two five-cell high-temperature electrolysis stacks constructed with advanced cell and stack technologies. The solid oxide cells incorporate a negative-electrode-supported multi-layer design with nickel-zirconia cermet negative electrodes, thin-film yttria-stabilized zirconia electrolytes, and multi-layer lanthanum ferrite-based positive electrodes. The per-cell active area is 100 cm2. The stack is internally manifolded with compliant mica-glass seals. Treated metallic interconnects with integral flow channels separate the cells. Stack compression is accomplished by means of a custom spring-loaded test fixture. Initial stack performance characterization was determined through a series of DC potential sweeps in both fuel cell and electrolysis modes of operation. Results of these sweeps indicated very good initial performance, with area-specific resistance values less than 0.5 ?.cm2. Long-term durability testing was performed with A test duration of 1000 hours. Overall performance degradation was less than 10% over the 1000-hour period. Final stack performance characterization was again determined by a series of DC potential sweeps at the same flow conditions as the initial sweeps in both electrolysis and fuel cell modes of operation. A final sweep in the fuel cell mode indicated a power density of 0.356 W/cm2, with average per-cell voltage of 0.71 V at a current of 50 A.

  8. Pulse-shape discrimination of scintillation from alpha and beta particles with liquid scintillator and Geiger-mode multipixel avalanche diodes

    E-Print Network [OSTI]

    Kreslo, I; Delaquis, S; Ereditato, A; Janos, S; Messina, M; Moser, U; Rossi, B; Zeller, M

    2011-01-01T23:59:59.000Z

    A successfull application of Geiger-mode multipixel avalanche diodes (GMAPDs) for pulse-shape discrimination in alpha-beta spectrometry using organic liquid scintillator is described in this paper. Efficient discrimination of alpha and beta components in the emission of radioactive isotopes is achieved for alpha energies above 0.3 MeV. The ultra-compact design of the scintillating detector helps to efficiently suppress cosmic-ray and ambient radiation background. This approach allows construction of hand-held robust devices for monitoring of radioactive contamination in various environmental conditions.

  9. Pulse-shape discrimination of scintillation from alpha and beta particles with liquid scintillator and Geiger-mode multipixel avalanche diodes

    E-Print Network [OSTI]

    I. Kreslo; I. Badhrees; S. Delaquis; A. Ereditato; S. Janos; M. Messina; U. Moser; B. Rossi; M. Zeller

    2011-06-23T23:59:59.000Z

    A successfull application of Geiger-mode multipixel avalanche diodes (GMAPDs) for pulse-shape discrimination in alpha-beta spectrometry using organic liquid scintillator is described in this paper. Efficient discrimination of alpha and beta components in the emission of radioactive isotopes is achieved for alpha energies above 0.3 MeV. The ultra-compact design of the scintillating detector helps to efficiently suppress cosmic-ray and ambient radiation background. This approach allows construction of hand-held robust devices for monitoring of radioactive contamination in various environmental conditions.

  10. Polarization State Dynamics of Single Photon Pulse Under Stochastic Polarization Mode Dispersion for Optical Fiber Quantum Channels

    E-Print Network [OSTI]

    Chang-hua Zhu; Chang-xing Pei; Dong-xiao Quan; Nan Chen; Yun-hui Yi

    2009-08-30T23:59:59.000Z

    We investigate the polarization state dynamics of single photon pulse for optical fiber quantum communication channels. On the basis of a birefringence vector model in which amplitude and direction are both stochastic variables, Jones vector is obtained by solving the frequency domain wave equation. The fidelity of output quantum state and degree of polarization of the pulse are also obtained from the density operators. It is shown that the fidelity of quantum state decreases quickly and tends to a stable value along optical fiber, and increases for larger mean fluctuation magnitude of the stochastic fiber birefringence. Degree of polarization is nearly constant for small mean fluctuation magnitude of the birefringence. The fidelity and degree of polarization vary in the same way for Gaussian and rectangular frequency spectrum envelope, while the value of Lorentzian spectrum is smaller.

  11. Nerve-pulse interactions

    SciTech Connect (OSTI)

    Scott, A.C.

    1982-01-01T23:59:59.000Z

    Some recent experimental and theoretical results on mechanisms through which individual nerve pulses can interact are reviewed. Three modes of interactions are considered: (1) interaction of pulses as they travel along a single fiber which leads to velocity dispersion; (2) propagation of pairs of pulses through a branching region leading to quantum pulse code transformations; and (3) interaction of pulses on parallel fibers through which they may form a pulse assembly. This notion is analogous to Hebb's concept of a cell assembly, but on a lower level of the neural hierarchy.

  12. Stabilized Ultrafast Pulse Generation and Optical Frequency Combs Techniques

    E-Print Network [OSTI]

    Van Stryland, Eric

    Stabilized Ultrafast Pulse Generation and Optical Frequency Combs ­ Techniques and Applications Diodes ­ Review Ultrafast Dynamics ­ Breathing Mode (Dispersion Managed Cavity) · High Pulse Energy to Make Short Pulses - Review Ultrafast Dynamics- - Dispersion Managed (Breathing Mode) MLL #12

  13. 40 IEEE TRANSACTIONS ON PLASMA SCIENCE, VOL. 30, NO. 1, FEBRUARY 2002 Simulation of Laser Pulse Amplification in a

    E-Print Network [OSTI]

    Wurtele, Jonathan

    . Index Terms--Lasers, optical pulse compression, Raman scattering. SHORT LASER pulses with high energy

  14. Long-term developments in Her X-1: Correlation between the histories of the 35 day turn-on cycle and the 1.24 sec pulse period

    E-Print Network [OSTI]

    R. Staubert; S. Schandl; D. Klochkov; J Wilms; K. Postnov; N. Shakura

    2007-02-20T23:59:59.000Z

    We have studied the long-term (1971-2005) behaviour of the 1.24 sec pulse period and the 35 day precession period of Her X-1 and show that both periods vary in a highly correlated way (see also Staubert et al. 1997 and 2000). When the spin-up rate decreases, the 35 day turn-on period shortens.This correlation is most evident on long time scales (~2000 days),e.g.around four extended spin-down episodes, but also on shorter time scales (a few 100 days) on which quasi-periodic variations are apparent. We argue that the likely common cause is variations of the mass accretion rate onto the neutron star.The data since 1991 allow a continuous sampling and indicate a lag between the turn-on behaviour and the spin behaviour, in the sense that changes are first seen in the spin, about one cycle later in the turn-on. Both the coronal wind model (Schandl & Meyer 1994) as well as the stream-disk model (Shakura et al.999) predict this kind of behaviour.

  15. The Role of Lithium Conditioning in Achieving High Performance, Long Pulse H-mode Discharges in the NSTX and EAST Devices

    SciTech Connect (OSTI)

    Maingi, Rajesh [PPPL; Mansfield, D. K. [PPPL; Gong, X. Z. [IPPCAS; Sun, Z. [IPPCAS; Bell, M. G. [PPPL

    2014-10-01T23:59:59.000Z

    In this paper, the role of lithium wall conditioning on the achievement of high performance, long pulse discharges in the National Spherical Torus Experiment (NSTX) and the Experimental Advanced Superconducting Tokamak (EAST) is documented. Common observations include recycling reduction and elimination of ELMs. In NSTX, lithium conditioning typically resulted in ELM-free operation with impurity accumulation, which was ameliorated e.g. with pulsed 3D fields to trigger controlled ELMs. Active lithium conditioning in EAST discharges has overcome this problem, producing an ELM-free Hmode with controlled density and impurities.

  16. Pulse transmission receiver with higher-order time derivative pulse correlator

    DOE Patents [OSTI]

    Dress Jr., William B.; Smith, Stephen F.

    2003-09-16T23:59:59.000Z

    Systems and methods for pulse-transmission low-power communication modes are disclosed. A pulse transmission receiver includes: a higher-order time derivative pulse correlator; a demodulation decoder coupled to the higher-order time derivative pulse correlator; a clock coupled to the demodulation decoder; and a pseudorandom polynomial generator coupled to both the higher-order time derivative pulse correlator and the clock. The systems and methods significantly reduce lower-frequency emissions from pulse transmission spread-spectrum communication modes, which reduces potentially harmful interference to existing radio frequency services and users and also simultaneously permit transmission of multiple data bits by utilizing specific pulse shapes.

  17. Preliminary study of pseudorandom binary sequence pulsing of ORELA

    SciTech Connect (OSTI)

    Larson, N. M.; Olsen, D. K.

    1980-03-01T23:59:59.000Z

    It has been suggested that pseudorandom binary sequence (PRBS) pulsing might enhance the performance of the Oak Ridge Electron Linear Accelerator (ORELA) for neutron-induced, time-of-flight (TOF) cross-section measurements. In this technical memorandum, equations are developed for expected count rates, statistical variances, and backgrounds for a pulsing scheme in which a PRBS is superimposed on the periodic equalintensity ORELA bursts. Introduction of the PRBS modification permits neutrons of different energies originating from different bursts to reach the detector simultaneously, and the signal corresponding to a unique flight time to be extracted mathematically. Relative advantages and disadvantages of measurements from conventional and PRBS pulsing modes are discussed in terms of counting statistics and backgrounds. Computer models of TOF spectra are generated for both pulsing modes, using as examples a 20-meter /sup 233/U fission-chamber measurement and a 155-meter /sup 238/U sample-in transmission measurement. Detailed comparisons of PRBS vs conventional results are presented. This study indicates that although PRBS pulsing could enhance ORELA performance for selected measurements, for general ORELA operation the disadvantages from PRBS pulsing probably outweigh the advantages.

  18. Pulsed-neutron monochromator

    DOE Patents [OSTI]

    Mook, Jr., Herbert A. (Oak Ridge, TN)

    1985-01-01T23:59:59.000Z

    In one aspect, the invention is an improved pulsed-neutron monochromator of the vibrated-crystal type. The monochromator is designed to provide neutron pulses which are characterized both by short duration and high density. A row of neutron-reflecting crystals is disposed in a neutron beam to reflect neutrons onto a common target. The crystals in the row define progressively larger neutron-scattering angles and are vibrated sequentially in descending order with respect to the size of their scattering angles, thus generating neutron pulses which arrive simultaneously at the target. Transducers are coupled to one end of the crystals to vibrate them in an essentially non-resonant mode. The transducers propagate transverse waves in the crystal which progress longitudinally therein. The wave are absorbed at the undriven ends of the crystals by damping material mounted thereon. In another aspect, the invention is a method for generating neutron pulses characterized by high intensity and short duration.

  19. Pulsed-neutron monochromator

    DOE Patents [OSTI]

    Mook, H.A. Jr.

    1984-01-01T23:59:59.000Z

    In one aspect, the invention is an improved pulsed-neutron monochromator of the vibrated-crystal type. The monochromator is designed to provide neutron pulses which are characterized both by short duration and high density. A row of neutron-reflecting crystals is disposed in a neutron beam to reflect neutrons onto a common target. The crystals in the row define progressively larger neutron-scattering angles and are vibrated sequentially in descending order with respect to the size of their scattering angles, thus generating neutron pulses which arrive simultaneously at the target. Transducers are coupled to one end of the crystals to vibrate them in an essentially non-resonant mode. The transducers propagate transverse waves in the crystal which progress longitudinally therein. The waves are absorbed at the undriven ends of the crystals by damping material mounted thereon. In another aspect, the invention is a method for generating neutron pulses characterized by high intensity and short duration.

  20. Analysis and experimental study on formation conditions of large-scale barrier-free diffuse atmospheric pressure air plasmas in repetitive pulse mode

    SciTech Connect (OSTI)

    Li, Lee, E-mail: leeli@mail.hust.edu.cn; Liu, Lun; Liu, Yun-Long; Bin, Yu; Ge, Ya-Feng; Lin, Fo-Chang [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, School of Electric and Electronic Engineering, HuaZhong University of Science and Technology (HUST), Wuhan 430074 (China)

    2014-01-14T23:59:59.000Z

    Atmospheric air diffuse plasmas have enormous application potential in various fields of science and technology. Without dielectric barrier, generating large-scale air diffuse plasmas is always a challenging issue. This paper discusses and analyses the formation mechanism of cold homogenous plasma. It is proposed that generating stable diffuse atmospheric plasmas in open air should meet the three conditions: high transient power with low average power, excitation in low average E-field with locally high E-field region, and multiple overlapping electron avalanches. Accordingly, an experimental configuration of generating large-scale barrier-free diffuse air plasmas is designed. Based on runaway electron theory, a low duty-ratio, high voltage repetitive nanosecond pulse generator is chosen as a discharge excitation source. Using the wire-electrodes with small curvature radius, the gaps with highly non-uniform E-field are structured. Experimental results show that the volume-scaleable, barrier-free, homogeneous air non-thermal plasmas have been obtained between the gap spacing with the copper-wire electrodes. The area of air cold plasmas has been up to hundreds of square centimeters. The proposed formation conditions of large-scale barrier-free diffuse air plasmas are proved to be reasonable and feasible.

  1. Low-noise pulse conditioner

    DOE Patents [OSTI]

    Bird, David A. (Oak Ridge, TN)

    1983-01-01T23:59:59.000Z

    A low-noise pulse conditioner is provided for driving electronic digital processing circuitry directly from differentially induced input pulses. The circuit uses a unique differential-to-peak detector circuit to generate a dynamic reference signal proportional to the input peak voltage. The input pulses are compared with the reference signal in an input network which operates in full differential mode with only a passive input filter. This reduces the introduction of circuit-induced noise, or jitter, generated in ground referenced input elements normally used in pulse conditioning circuits, especially speed transducer processing circuits.

  2. Pulse transmission transceiver architecture for low power communications

    DOE Patents [OSTI]

    Dress, Jr., William B.; Smith, Stephen F.

    2003-08-05T23:59:59.000Z

    Systems and methods for pulse-transmission low-power communication modes are disclosed. A method of pulse transmission communications includes: generating a modulated pulse signal waveform; transforming said modulated pulse signal waveform into at least one higher-order derivative waveform; and transmitting said at least one higher-order derivative waveform as an emitted pulse. The systems and methods significantly reduce lower-frequency emissions from pulse transmission spread-spectrum communication modes, which reduces potentially harmful interference to existing radio frequency services and users and also simultaneously permit transmission of multiple data bits by utilizing specific pulse shapes.

  3. Pulse stretcher

    DOE Patents [OSTI]

    Horton, J.A.

    1994-05-03T23:59:59.000Z

    Apparatus for increasing the length of a laser pulse to reduce its peak power without substantial loss in the average power of the pulse is disclosed. The apparatus uses a White cell having a plurality of optical delay paths of successively increasing number of passes between the field mirror and the objective mirrors. A pulse from a laser travels through a multi-leg reflective path between a beam splitter and a totally reflective mirror to the laser output. The laser pulse is also simultaneously injected through the beam splitter to the input mirrors of the optical delay paths. The pulses from the output mirrors of the optical delay paths go simultaneously to the laser output and to the input mirrors of the longer optical delay paths. The beam splitter is 50% reflective and 50% transmissive to provide equal attenuation of all of the pulses at the laser output. 6 figures.

  4. 838 IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. 42, NO. 8, AUGUST 2006 50-GHz Passively Mode-Locked Surface-Emitting

    E-Print Network [OSTI]

    Keller, Ursula

    designs. The experimental setup is very versatile and its design and construction are discussed in detail. Index Terms--Mode locking, pulsed lasers, semiconductor lasers, thermal lens. I. INTRODUCTION can be fabricated cost-effectively by wafer-scale mass production. With an eye on the 100-GHz mark

  5. Modelling CollidingPulse ModeLocked

    E-Print Network [OSTI]

    have been made by S. D. Brorson, T. Franck, M. Hofmann and L. Prip at Tele Danmark R & D. #12; iv #12, which are identical to those employed in the CPM lasers fabricated at Tele Danmark R & D

  6. Closed-loop pulsed helium ionization detector

    DOE Patents [OSTI]

    Ramsey, Roswitha S. (Knoxville, TN); Todd, Richard A. (Knoxville, TN)

    1987-01-01T23:59:59.000Z

    A helium ionization detector for gas chromatography is operated in a constant current, pulse-modulated mode by configuring the detector, electrometer and a high voltage pulser in a closed-loop control system. The detector current is maintained at a fixed level by varying the frequency of fixed-width, high-voltage bias pulses applied to the detector. An output signal proportional to the pulse frequency is produced which is indicative of the charge collected for a detected species.

  7. EIGHT CHANNEL PROGRAMMABLE PULSE GENERATOR

    E-Print Network [OSTI]

    Kleinfeld, David

    Master-8 EIGHT CHANNEL PROGRAMMABLE PULSE GENERATOR Operation Manual A.M.P.I. A.M.P.I. 123Uzlel St and the programming simple and easy to learn. Master-8 is an attractive unit and you will enjoy working with its eight -- Modes of operation 11 -- Setting the parameters 13 -- Triggering 14 -- Eight stored paradigms 14

  8. Broadband laser cooling of trapped atoms with ultrafast pulses

    E-Print Network [OSTI]

    Blinov, Boris

    Broadband laser cooling of trapped atoms with ultrafast pulses B. B. Blinov,* R. N. Kohn, Jr., M. J ions in an rf trap using ultrafast pulses from a mode-locked laser. The temperature of a single ion On the other hand, an ultrafast laser whose pulse is a few picoseconds long will naturally have a bandwidth

  9. Low-noise pulse conditioner

    DOE Patents [OSTI]

    Bird, D.A.

    1981-06-16T23:59:59.000Z

    A low-noise pulse conditioner is provided for driving electronic digital processing circuitry directly from differentially induced input pulses. The circuit uses a unique differential-to-peak detector circuit to generate a dynamic reference signal proportional to the input peak voltage. The input pulses are compared with the reference signal in an input network which operates in full differential mode with only a passive input filter. This reduces the introduction of circuit-induced noise, or jitter, generated in ground referenced input elements normally used in pulse conditioning circuits, especially speed transducer processing circuits. This circuit may be used for conditioning the sensor signal from the Fidler coil in a gas centrifuge for separation of isotopic gaseous mixtures.

  10. System and process for pulsed multiple reaction monitoring

    DOE Patents [OSTI]

    Belov, Mikhail E

    2013-05-17T23:59:59.000Z

    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.

  11. Source term evaluation for postulated UF{sub 6} release accidents in gaseous diffusion plants -- Summer ventilation mode (non-seismic cases)

    SciTech Connect (OSTI)

    Kim, S.H.; Chen, N.C.J.; Taleyarkhan, R.P.; Wendel, M.W.; Keith, K.D.; Schmidt, R.W. [Oak Ridge National Lab., TN (United States); Carter, J.C. [J.C. Carter Associates, Inc., Knoxville, TN (United States); Dyer, R.H. [Dyer Enterprises, Harriman, TN (United States)

    1996-12-30T23:59:59.000Z

    Computer models have been developed to simulate the transient behavior of aerosols and vapors as a result of a postulated accident involving the release of uranium hexafluoride (UF{sub 6}) into the process building of a gaseous diffusion plant. For the current study, gaseous UF{sub 6} is assumed to get released in the cell housing atmosphere through B-line break at 58.97 kg/s for 10 min and 30 min duration at the Paducah and Portsmouth Gaseous Diffusion Plants. The released UF{sub 6} undergoes an exothermic chemical reaction with moisture (H{sub 2}O) in the air to form hydrogen fluoride (HF) and radioactive uranyl fluoride (UO{sub 2}F{sub 2}) while it disperses throughout the process building. As part of a facility-wide safety evaluation, this study evaluated source terms consisting of UO{sub 2}F{sub 2} as well as HF during a postulated UF{sub 6} release accident in a process building. UO{sub 2}F{sub 2} mainly remains as airborne-solid particles (aerosols), and HF is in a vapor form. Some UO{sub 2}F{sub 2} aerosols are removed from the air flow due to gravitational settling. The HF and the remaining UO{sub 2}F{sub 2} are mixed with air and exhausted through the building ventilation system. The MELCOR computer code was selected for simulating aerosols and vapor transport in the process building. To characterize leakage flow through the cell housing wall, 3-D CFD tool (CFDS-FLOW3D) was used. About 57% of UO{sub 2}F{sub 2} was predicted to be released into the environment. Since HF was treated as vapor, close to 100% was estimated to get released into the environment.

  12. October 1, 2003 / Vol. 28, No. 19 / OPTICS LETTERS 1835 Picosecond-pulse amplification with an external

    E-Print Network [OSTI]

    Xie, Xiaoliang Sunney

    of generating high-repetition-rate pulse trains (250 kHz) with microjoule pulse energies.2 Alternatively, pulses-locked picosecond Ti:sapphire laser to pulse energies of more than 150 nJ. © 2003 Optical Society of America OCIS codes: 320.7080, 140.4480, 300.6220. The nanojoule-scale pulse energies obtained directly from a mode

  13. Effect of noise on the power spectrum of passively mode-locked lasers

    SciTech Connect (OSTI)

    Eliyahu, D.; Salvatore, R.A.; Yariv, A. [California Institute of Technology, M/S 128-95, Pasadena, California 91125 (United States)

    1997-01-01T23:59:59.000Z

    We analyze the effects of noise on the power spectrum of pulse trains generated by a continuously operating passively mode-locked laser. The shape of the different harmonics of the power spectrum is calculated in the presence of correlated timing fluctuations between neighboring pulses and in the presence of amplitude fluctuations. The spectra at the different harmonics are influenced mainly by the nonstationary timing-jitter fluctuations; amplitude fluctuations slightly modify the spectral tails. Estimation of the coupling term between the longitudinal cavity modes or the effective saturable absorber coefficient is made from the timing-jitter correlation time. Experimental results from an external cavity two-section semiconductor laser are given. The results show timing-jitter fluctuations having a relaxation time much longer than the repetition period. {copyright} 1997 Optical Society of America.

  14. Pulsed hydrojet

    DOE Patents [OSTI]

    Bohachevsky, I.O.; Torrey, M.D.

    1986-06-10T23:59:59.000Z

    An underwater pulsed hydrojet propulsion system is provided for accelerating and propelling a projectile or other vessel. A reactant, such as lithium, is fluidized and injected into a water volume. The resulting reaction produces an energy density in a time effective to form a steam pocket. Thrust flaps or baffles direct the pressure from the steam pocket toward an exit nozzle for accelerating a water volume to create thrust. A control system regulates the dispersion of reactant to control thrust characteristics.

  15. Microanalysis of VLSI InterconnectFailure Modes under Short-Pulse Stress Kaustav Banerjee, Dae-Yong Kim, Ajith Amerasekerat, Chenming Hull, S. Simon Wong and Kenneth E. Goodson

    E-Print Network [OSTI]

    level metallization system [6]. The higher self-heating of Metal 4 line (with 2X thicker AlCu than other be detected under optical microscope and no change in the electrical resistance of these lines can be measured to be introduced by sub-critical current pulses that does not affect the electrical resistance of the line

  16. A terahertz pulse emitter monolithically integrated with a quantum cascade laser

    E-Print Network [OSTI]

    Kao, Tsung-Yu

    A terahertz pulse emitter monolithically integrated with a quantum cascade laser(QCL) is demonstrated. The emitter facet is excited by near-infrared pulses from a mode-locked Ti:sapphire laser, and the resulting current ...

  17. Method to calibrate fission chambers in Campbelling mode

    SciTech Connect (OSTI)

    Geslot, Benoit; Filliatre, Philippe; Jammes, Christian; Di Salvo, Jacques; Breaud, Stephane; Villard, Jean-Francois [CEA, DEN, Cadarache, SPEx, LDCI, F-13108 S Paul Lez Durance, (France); Unruh, Troy C. [INL, Idaho Natl Lab, Idaho Falls, ID 83415 (United States)

    2012-08-15T23:59:59.000Z

    Fission chambers are neutron detectors which are widely used to instrument experimental reactors such as material testing reactors or zero power reactors. In the presence of a high level mixed gamma and neutron flux, fission chambers can be operated in Campbelling mode (also known as 'fluctuation mode' or 'mean square voltage mode') to provide reliable and precise neutron related measurements. Fission chamber calibration in Campbelling mode (in terms of neutron flux) is usually done empirically using a calibrated reference detector. A major drawback of this method is that calibration measurements have to be performed in a neutron environment very similar to the one in which the calibrated detector will be used afterwards. What is proposed here is a different approach based on characterizing the fission chamber response in terms of fission rate. This way, the detector calibration coefficient is independent from the neutron spectrum and can be determined prior to the experiment. The fissile deposit response to the neutron spectrum can then be assessed independently by other means (experimental or numerical). In this paper, the response of CEA-made miniature fission chambers in Campbelling mode is studied. A theoretical model of the signal is used to calculate the calibration coefficient. The model's input parameters come from statistical distribution of individual pulses. Supporting measurements were made in the CEA Cadarache zero power reactor MINERVE and results are compared to an empirical Campbelling mode calibration. The tested fission chamber calibration coefficient is roughly 2*10{sup -26} A{sup 2}/Hz/(c/s). Both numerical and empirical methods give consistent results, however a deviation of about 15% was observed. (authors)

  18. Pulse transmission receiver with higher-order time derivative pulse generator

    DOE Patents [OSTI]

    Dress Jr., William B.; Smith, Stephen F.

    2003-08-12T23:59:59.000Z

    Systems and methods for pulse-transmission low-power communication modes are disclosed. A pulse transmission receiver includes: a front-end amplification/processing circuit; a synchronization circuit coupled to the front-end amplification/processing circuit; a clock coupled to the synchronization circuit; a trigger signal generator coupled to the clock; and at least one higher-order time derivative pulse generator coupled to the trigger signal generator. The systems and methods significantly reduce lower-frequency emissions from pulse transmission spread-spectrum communication modes, which reduces potentially harmful interference to existing radio frequency services and users and also simultaneously permit transmission of multiple data bits by utilizing specific pulse shapes.

  19. Note: Emittance measurements of intense pulsed proton beam for different pulse length and repetition rate

    SciTech Connect (OSTI)

    Miracoli, R. [ESS Bilbao, Vizcaya (Spain); INFN - Laboratori Nazionali del Sud, via S. Sofia 62, 95123 Catania (Italy); Gammino, S.; Celona, L.; Mascali, D. [INFN - Laboratori Nazionali del Sud, via S. Sofia 62, 95123 Catania (Italy); Castro, G. [INFN - Laboratori Nazionali del Sud, via S. Sofia 62, 95123 Catania (Italy); Universita degli studi di Catania, Dipartimento di Fisica e Astronomia, V. S. Sofia 64, 95123 Catania (Italy); Gobin, R.; Delferriere, O.; Adroit, G.; Senee, F. [CEA-IRFU, Gif sur Yvette Cedex (France); Ciavola, G. [INFN - Laboratori Nazionali del Sud, via S. Sofia 62, 95123 Catania (Italy); CNAO, Str. Pr. Campeggi, Pavia (Italy)

    2012-05-15T23:59:59.000Z

    The high intensity ion source (SILHI), in operation at CEA-Saclay, has been used to produce a 90 mA pulsed proton beam with pulse length and repetition rates suitable for the European Spallation Source (ESS) linac. Typical r-r{sup '} rms normalized emittance values smaller than 0.2{pi} mm mrad have been measured for operation in pulsed mode (0.01 < duty cycle < 0.15 and 1 ms < pulse duration < 10 ms) that are relevant for the design update of the Linac to be used at the ESS in Lund.

  20. Tapered pulse tube for pulse tube refrigerators

    DOE Patents [OSTI]

    Swift, Gregory W. (Sante Fe, NM); Olson, Jeffrey R. (San Mateo, CA)

    1999-01-01T23:59:59.000Z

    Thermal insulation of the pulse tube in a pulse-tube refrigerator is maintained by optimally varying the radius of the pulse tube to suppress convective heat loss from mass flux streaming in the pulse tube. A simple cone with an optimum taper angle will often provide sufficient improvement. Alternatively, the pulse tube radius r as a function of axial position x can be shaped with r(x) such that streaming is optimally suppressed at each x.

  1. Fast pulsed excitation wiggler or undulator

    DOE Patents [OSTI]

    van Steenbergen, Arie (Shoreham, NY)

    1990-01-01T23:59:59.000Z

    A fast pulsed excitation, electromagnetic undulator or wiggler, employing geometrically alternating substacks of thin laminations of ferromagnetic material, together with a single turn current loop excitation of the composite assembly, of such shape and configuration that intense, spatially alternating, magnetic fields are generated; for use as a pulsed mode undulator or wiggler radiator, for use in a Free Electron Laser (FEL) type radiation source or, for use in an Inverse Free Electron Laser (IFEL) charged particle accelerator.

  2. Laser mode hyper-combs Alon Schwartz and Baruch Fischer*

    E-Print Network [OSTI]

    Fischer, Baruch

    , and G. Angelow, "Toward single-cycle laser systems," IEEE J. Select. Topics in Quantum. Electron. 9, 990. Fischer, "Melting and freezing of light pulses and modes in mode-locked lasers," Opt. Express 11(25), 3418Laser mode hyper-combs Alon Schwartz and Baruch Fischer* Department of Electrical Engineering

  3. Excitation of two atoms by a propagating single photon pulse

    E-Print Network [OSTI]

    Navneeth Ramakrishnan; Yimin Wang; Valerio Scarani

    2014-11-13T23:59:59.000Z

    We describe the interaction of two two-level atoms in free space with propagating modes of the quantized electromagnetic field, using the time-dependent Heisenberg-Langevin method. For single- photon pulses, we consider the effect of the pulse's spatial and temporal profiles on the atomic excitation. In particular, we find the ideal shape for a pulse to put exactly one excitation in any desired state of the bi-atomic system. Furthermore, we analyze the differences in the atomic dynamics between the cases of Fock state pulses and coherent state pulses.

  4. Fault tolerant pulse synchronization

    E-Print Network [OSTI]

    Deconda, Keerthi

    2009-05-15T23:59:59.000Z

    Pulse synchronization is the evolution of spontaneous firing action across a network of sensor nodes. In the pulse synchronization model all nodes across a network produce a pulse, or "fire", at regular intervals even without access to a shared...

  5. Pulse transmission transmitter including a higher order time derivate filter

    DOE Patents [OSTI]

    Dress Jr., William B.; Smith, Stephen F.

    2003-09-23T23:59:59.000Z

    Systems and methods for pulse-transmission low-power communication modes are disclosed. A pulse transmission transmitter includes: a clock; a pseudorandom polynomial generator coupled to the clock, the pseudorandom polynomial generator having a polynomial load input; an exclusive-OR gate coupled to the pseudorandom polynomial generator, the exclusive-OR gate having a serial data input; a programmable delay circuit coupled to both the clock and the exclusive-OR gate; a pulse generator coupled to the programmable delay circuit; and a higher order time derivative filter coupled to the pulse generator. The systems and methods significantly reduce lower-frequency emissions from pulse transmission spread-spectrum communication modes, which reduces potentially harmful interference to existing radio frequency services and users and also simultaneously permit transmission of multiple data bits by utilizing specific pulse shapes.

  6. Soliton mode-locking in optical microresonators

    E-Print Network [OSTI]

    Herr, T; Gorodetsky, M L; Kippenberg, T J

    2012-01-01T23:59:59.000Z

    The discovery of mode-locking via saturable absorbers has led to optical femto-second pulses with applications ranging from eye-surgery to the analysis of chemical reactions on ultra-short timescales. In the frequency domain a train of such optical pulses corresponds to a frequency comb (equidistant optical laser lines spaced by the pulse repetition rate), which find use in precision spectroscopy and optical frequency metrology. Not relying on mode-locking, frequency combs can also be generated in continuously driven high-Q Kerr-nonlinear optical microresonators via cascaded four-wave mixing. Over the past years these Kerr-combs have been demonstrated in a variety of microresonator geometries. Applying a pulse-shaping mode locking mechanism, could enable compact femto-second pulse generators. However, conventional saturable absorbers are challenging to apply to microresonators, as they affect the high-quality-factor. Here, we report on passive mode-locking in microresonators without saturable absorber. This m...

  7. Long pulse production from short pulses

    DOE Patents [OSTI]

    Toeppen, John S. (Livermore, CA)

    1994-01-01T23:59:59.000Z

    A method of producing a long output pulse (SA) from a short pump pulse (P), using an elongated amplified fiber (11) having a doped core (12) that provides an amplifying medium for light of one color when driven into an excited state by light of a shorter wavelength and a surrounding cladding 13. A seed beam (S) of the longer wavelength is injected into the core (12) at one end of the fiber (11) and a pump pulse (P) of the shorter wavelength is injected into the cladding (13) at the other end of the fiber (11). The counter-propagating seed beam (S) and pump pulse (P) will produce an amplified output pulse (SA) having a time duration equal to twice the transit time of the pump pulse (P) through the fiber (11) plus the length of the pump pulse (P).

  8. Long pulse production from short pulses

    DOE Patents [OSTI]

    Toeppen, J.S.

    1994-08-02T23:59:59.000Z

    A method of producing a long output pulse from a short pump pulse is disclosed, using an elongated amplified fiber having a doped core that provides an amplifying medium for light of one color when driven into an excited state by light of a shorter wavelength and a surrounding cladding. A seed beam of the longer wavelength is injected into the core at one end of the fiber and a pump pulse of the shorter wavelength is injected into the cladding at the other end of the fiber. The counter-propagating seed beam and pump pulse will produce an amplified output pulse having a time duration equal to twice the transit time of the pump pulse through the fiber plus the length of the pump pulse. 3 figs.

  9. Optical time of flight studies of lithium plasma in double pulse laser ablation: Evidence of inverse Bremsstrahlung absorption

    SciTech Connect (OSTI)

    Sivakumaran, V.; Joshi, H. C.; Singh, R. K.; Kumar, Ajai, E-mail: ajai@ipr.res.in [Institute for Plasma Research, Bhat, Gandhinagar, Gujarat 382428 (India)

    2014-06-15T23:59:59.000Z

    The early stage of formation of lithium plasma in a collinear—double pulse laser ablation mode has been studied using optical time of flight (OTOF) spectroscopy as a function of inter-pulse delay time, the distance from the target surface and the fluence of the ablation lasers. The experimental TOF measurements were carried out for lithium neutral (670.8?nm and 610.3?nm), and ionic (548.4?nm and 478.8?nm) lines. These experimental observations have been compared with that for single pulse laser ablation mode. It is found that depending on the fluence and laser pulse shape of the first pre-ablation laser and the second main ablation laser, the plasma plume formation and its characteristic features can be described in terms of plume-plume or laser-plume interaction processes. Moreover, the enhancement in the intensity of Li neutral and ionic lines is observed when the laser-plume interaction is the dominant process. Here, we see the evidence of the role of inverse Bremsstrahlung absorption process in the initial stage of formation of lithium plasma in this case.

  10. Static magnetic and microwave properties of Li-ferrite films prepared by pulsed laser deposition

    E-Print Network [OSTI]

    Patton, Carl

    Static magnetic and microwave properties of Li-ferrite films prepared by pulsed laser deposition F University, Fort Collins, Colorado 80523 Highly textured Li-ferrite films have been synthesized by pulsed approaching 1000 °C the growth mode was predominantly 333 . A similar growth mode was recently reported for Ni-ferrite

  11. Properties of water surface discharge at different pulse repetition rates

    SciTech Connect (OSTI)

    Ruma,; Yoshihara, K. [Graduate School of Science and Technology, Kumamoto University, Kumamoto 860-8555 (Japan); Hosseini, S. H. R., E-mail: hosseini@kumamoto-u.ac.jp; Sakugawa, T.; Akiyama, H. [Graduate School of Science and Technology, Kumamoto University, Kumamoto 860-8555 (Japan); Institute of Pulsed Power Science, Kumamoto University, Kumamoto 860-8555 (Japan); Akiyama, M. [Department of Electrical and Electronic Engineering, Kagoshima University, Kagoshima 890-0065 (Japan); Lukeš, P. [Institute of Plasma Physics, AS CR, Prague, Prague 18200 (Czech Republic)

    2014-09-28T23:59:59.000Z

    The properties of water surface discharge plasma for variety of pulse repetition rates are investigated. A magnetic pulse compression (MPC) pulsed power modulator able to deliver pulse repetition rates up to 1000?Hz, with 0.5?J per pulse energy output at 25?kV, was used as the pulsed power source. Positive pulse with a point-to-plane electrode configuration was used for the experiments. The concentration and production yield of hydrogen peroxide (H{sub 2}O{sub 2}) were quantitatively measured and orange II organic dye was treated, to evaluate the chemical properties of the discharge reactor. Experimental results show that the physical and chemical properties of water surface discharge are not influenced by pulse repetition rate, very different from those observed for under water discharge. The production yield of H{sub 2}O{sub 2} and degradation rate per pulse of the dye did not significantly vary at different pulse repetition rates under a constant discharge mode on water surface. In addition, the solution temperature, pH, and conductivity for both water surface and underwater discharge reactors were measured to compare their plasma properties for different pulse repetition rates. The results confirm that surface discharge can be employed at high pulse repetition rates as a reliable and advantageous method for industrial and environmental decontamination applications.

  12. Theoretical description of spontaneous pulse formation in a semiconductor microring laser

    SciTech Connect (OSTI)

    Gil, L.; Columbo, L. [Institut du Non Lineaire de Nice (Unite Mixte de Recherche-Centre National de la Recherche Scientifique 6618) Universite de Nice Sophia Antipolis, 1361 Route des Lucioles, F-06560 Valbonne (France); Consiglio Nazionale delle Ricerche-Istituto di Fotonica e Nanotecnologie, Dipartimento Interuniversitario di Fisica, via Amendola, 173, 70126 Bari (Italy)

    2011-01-15T23:59:59.000Z

    We theoretically describe the spontaneous formation of stable pulses in a GaAs bulk semiconductor microring laser. These pulses are obtained without active or passive mode locking. We show that the parameter regime associated with their existence is limited on one side by the phase instability of the continuous-wave solution, and on the other side by the failure of Lamb's mode-locking criterion. Bistability between the continuous-wave solution and the spontaneous pulses is observed.

  13. Deep reflection-mode photoacoustic imaging of

    E-Print Network [OSTI]

    Wang, Lihong

    near-infrared laser pulses of 804-nm wavelength for PA excitation to achieve deep penetration-frequency PAM system. To achieve deep penetration of light, we chose the 804-nm near-infrared wavelengthDeep reflection-mode photoacoustic imaging of biological tissue Kwang Hyun Song and Lihong V. Wang

  14. A THz transverse electromagnetic mode two-dimensional interconnect layer incorporating quasi-optics

    E-Print Network [OSTI]

    of transmitting subpicosecond pulses in the transverse electromagnetic TEM mode over arbitrarily long paths near the cutoff fre- quency. Such pulse broadening does not occur for the trans- verse electromagneticA THz transverse electromagnetic mode two-dimensional interconnect layer incorporating quasi

  15. Theoretical analysis of actively mode-locked fiber ring laser with semiconductor optical amplifier

    E-Print Network [OSTI]

    Xu, Qianfan

    -locking; Fiber laser; Semiconductor optical amplifier 1. Introduction Ultra-short pulse sources are key devices for generating ultra-short pulse series. Various mode-locked lasers with higher than 10 GHz repetition have beenTheoretical analysis of actively mode-locked fiber ring laser with semiconductor optical amplifier

  16. Laser pulse stacking method

    DOE Patents [OSTI]

    Moses, E.I.

    1992-12-01T23:59:59.000Z

    A laser pulse stacking method is disclosed. A problem with the prior art has been the generation of a series of laser beam pulses where the outer and inner regions of the beams are generated so as to form radially non-synchronous pulses. Such pulses thus have a non-uniform cross-sectional area with respect to the outer and inner edges of the pulses. The present invention provides a solution by combining the temporally non-uniform pulses in a stacking effect to thus provide a more uniform temporal synchronism over the beam diameter. 2 figs.

  17. Topological modes driven by Lyapunov control

    E-Print Network [OSTI]

    Z. C. Shi; X. L. Zhao; X. X. Yi

    2014-11-20T23:59:59.000Z

    By Lyapunov control, we present a proposal to drive quasiparticles into a topological mode in quantum systems described by quadratic Hamiltonian. The merit of this control strategy is that only manipulation of the boundary sites are required, and the proposal works for both Fermi and Bose systems. We take the Kitaev's chain as an illustration for Fermi system and show that by manipulating the chemical potential of the boundary sites, we can steer an arbitrary excitation mode into the Majorana zero mode. For Bose system, taking the noninteracting Su-Schrieffer-Heeger (SSH) model as an example, we illustrate how to drive the system into the edge mode, i.e., the mode localized at the boundary sites. Finally, we explore the possibility to replace the continuous control field by square wave pulses.

  18. Method and means of transmitting and receiving broad-band unipolar, ultrasonic pulses for ultrasonic inspection

    DOE Patents [OSTI]

    Thompson, D.O.; Hsu, D.K.

    1993-12-14T23:59:59.000Z

    The invention includes a means and method for transmitting and receiving broadband, unipolar, ultrasonic pulses for ultrasonic inspection. The method comprises generating a generally unipolar ultrasonic stress pulse from a low impedance voltage pulse transmitter along a low impedance electrical pathway to an ultrasonic transducer, and receiving the reflected echo of the pulse by the transducer, converting it to a voltage signal, and passing it through a high impedance electrical pathway to an output. The means utilizes electrical components according to the method. The means and method allow a single transducer to be used in a pulse/echo mode, and facilitates alternatingly transmitting and receiving the broadband, unipolar, ultrasonic pulses. 25 figures.

  19. Method and means of transmitting and receiving broad-band unipolar, ultrasonic pulses for ultrasonic inspection

    DOE Patents [OSTI]

    Thompson, Donald O. (Ames, IA); Hsu, David K. (Ames, IA)

    1993-12-14T23:59:59.000Z

    The invention includes a means and method for transmitting and receiving broadband, unipolar, ultrasonic pulses for ultrasonic inspection. The method comprises generating a generally unipolar ultrasonic stress pulse from a low impedance voltage pulse transmitter along a low impedance electrical pathway to an ultrasonic transducer, and receiving the reflected echo of the pulse by the transducer, converting it to a voltage signal, and passing it through a high impedance electrical pathway to an output. The means utilizes electrical components according to the method. The means and method allow a single transducer to be used in a pulse/echo mode, and facilitates alternatingly transmitting and receiving the broadband, unipolar, ultrasonic pulses.

  20. Optically pulsed electron accelerator

    DOE Patents [OSTI]

    Fraser, J.S.; Sheffield, R.L.

    1985-05-20T23:59:59.000Z

    An optically pulsed electron accelerator can be used as an injector for a free electron laser and comprises a pulsed light source, such as a laser, for providing discrete incident light pulses. A photoemissive electron source emits electron bursts having the same duration as the incident light pulses when impinged upon by same. The photoemissive electron source is located on an inside wall of a radiofrequency-powered accelerator cell which accelerates the electron burst emitted by the photoemissive electron source.

  1. Optically pulsed electron accelerator

    DOE Patents [OSTI]

    Fraser, John S. (Los Alamos, NM); Sheffield, Richard L. (Los Alamos, NM)

    1987-01-01T23:59:59.000Z

    An optically pulsed electron accelerator can be used as an injector for a free electron laser and comprises a pulsed light source, such as a laser, for providing discrete incident light pulses. A photoemissive electron source emits electron bursts having the same duration as the incident light pulses when impinged upon by same. The photoemissive electron source is located on an inside wall of a radio frequency powered accelerator cell which accelerates the electron burst emitted by the photoemissive electron source.

  2. Hybrid chirped pulse amplification system

    DOE Patents [OSTI]

    Barty, Christopher P.; Jovanovic, Igor

    2005-03-29T23:59:59.000Z

    A hybrid chirped pulse amplification system wherein a short-pulse oscillator generates an oscillator pulse. The oscillator pulse is stretched to produce a stretched oscillator seed pulse. A pump laser generates a pump laser pulse. The stretched oscillator seed pulse and the pump laser pulse are directed into an optical parametric amplifier producing an optical parametric amplifier output amplified signal pulse and an optical parametric amplifier output unconverted pump pulse. The optical parametric amplifier output amplified signal pulse and the optical parametric amplifier output laser pulse are directed into a laser amplifier producing a laser amplifier output pulse. The laser amplifier output pulse is compressed to produce a recompressed hybrid chirped pulse amplification pulse.

  3. Development of a 1319-nm Laser Radar Using Fiber Optics and RF Pulse Compression

    E-Print Network [OSTI]

    Kansas, University of

    Development of a 1319-nm Laser Radar Using Fiber Optics and RF Pulse Compression Christopher T of this concept. Our laboratory breadboard uses standard, single-mode optical fiber, off-the-shelf fiber-optic IMPLEMENTATION 3.1 Transmitter--Single-mode laser 3.2 Transmitter--Single-mode fiber 3.3 Transmitter--Optical

  4. Mode spectrum and temporal soliton formation in optical microresonators

    E-Print Network [OSTI]

    Herr, T; Jost, J D; Mirgorodskiy, I; Lihachev, G; Gorodetsky, M L; Kippenberg, T J

    2013-01-01T23:59:59.000Z

    The formation of temporal dissipative solitons in optical microresonators enables compact, high repetition rate sources of ultra-short pulses as well as low noise, broadband optical frequency combs with smooth spectral envelopes. Here we study the influence of the resonator mode spectrum on temporal soliton formation. Using frequency comb assisted diode laser spectroscopy, the measured mode structure of crystalline MgF2 resonators are correlated with temporal soliton formation. While an overal general anomalous dispersion is required, it is found that higher order dispersion can be tolerated as long as it does not dominate the resonator's mode structure. Mode coupling induced avoided crossings in the resonator mode spectrum are found to prevent soliton formation, when affecting resonator modes close to the pump laser. The experimental observations are in excellent agreement with numerical simulations based on the nonlinear coupled mode equations, which reveal the rich interplay of mode crossings and soliton f...

  5. High voltage pulse conditioning

    DOE Patents [OSTI]

    Springfield, Ray M. (Sante Fe, NM); Wheat, Jr., Robert M. (Los Alamos, NM)

    1990-01-01T23:59:59.000Z

    Apparatus for conditioning high voltage pulses from particle accelerators in order to shorten the rise times of the pulses. Flashover switches in the cathode stalk of the transmission line hold off conduction for a determinable period of time, reflecting the early portion of the pulses. Diodes upstream of the switches divert energy into the magnetic and electrostatic storage of the capacitance and inductance inherent to the transmission line until the switches close.

  6. Critical pulse power components

    SciTech Connect (OSTI)

    Sarjeant, W.J.; Rohwein, G.J.

    1981-01-01T23:59:59.000Z

    Critical components for pulsed power conditioning systems will be reviewed. Particular emphasis will be placed on those components requiring significant development efforts. Capacitors, for example, are one of the weakest elements in high-power pulsed systems, especially when operation at high-repetition frequencies for extended periods of time are necessary. Switches are by far the weakest active components of pulse power systems. In particular, opening switches are essentially nonexistent for most applications. Insulaton in all systems and components requires development and improvement. Efforts under way in technology base development of pulse power components will be discussed.

  7. Invited Article: Coherent imaging using seeded free-electron laser pulses with variable polarization: First results and research opportunities

    SciTech Connect (OSTI)

    Capotondi, F.; Pedersoli, E.; Mahne, N.; Menk, R. H.; Passos, G.; Raimondi, L.; Svetina, C.; Sandrin, G.; Kiskinova, M. [FERMI, Elettra-Sincrotrone Trieste, SS 14 - km 163.5, 34149 Basovizza, Trieste (Italy); Zangrando, M. [FERMI, Elettra-Sincrotrone Trieste, SS 14 - km 163.5, 34149 Basovizza, Trieste (Italy); CNR, Istituto Officina dei Materiali - TASC, SS 14 - km 163.5, 34149 Basovizza, Trieste (Italy); Bajt, S.; Barthelmess, M.; Fleckenstein, H.; Chapman, H. N. [CFEL-DESY, Notkestrasse 85, 22607 Hamburg (Germany); Schulz, J. [European XFEL GmbH, Albert-Einstein-Ring 19, 22761 Hamburg (Germany); Bach, J.; Froemter, R. [Universitaet Hamburg, Institut fuer Angewandte Physik, 20355 Hamburg (Germany); Schleitzer, S.; Mueller, L.; Gutt, C. [DESY, Notkestrasse 85, 22607 Hamburg (Germany); and others

    2013-05-15T23:59:59.000Z

    FERMI-Elettra, the first vacuum ultraviolet and soft X-ray free-electron laser (FEL) using by default a 'seeded' scheme, became operational in 2011 and has been opened to users since December 2012. The parameters of the seeded FERMI FEL pulses and, in particular, the superior control of emitted radiation in terms of spectral purity and stability meet the stringent requirements for single-shot and resonant coherent diffraction imaging (CDI) experiments. The advantages of the intense seeded FERMI pulses with variable polarization have been demonstrated with the first experiments performed using the multipurpose experimental station operated at the diffraction and projection imaging (DiProI) beamline. The results reported here were obtained with fixed non-periodic targets during the commissioning period in 2012 using 20-32 nm wavelength range. They demonstrate that the performance of the FERMI FEL source and the experimental station meets the requirements of CDI, holography, and resonant magnetic scattering in both multi- and single-shot modes. Moreover, we present the first magnetic scattering experiments employing the fully circularly polarized FERMI pulses. The ongoing developments aim at pushing the lateral resolution by using shorter wavelengths provided by double-stage cascaded FERMI FEL-2 and probing ultrafast dynamic processes using different pump-probe schemes, including jitter-free seed laser pump or FEL-pump/FEL-probe with two color FEL pulses generated by the same electron bunch.

  8. Sandia National Laboratories: MODE

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    MODE Sandia and EMCORE: Solar Photovoltaics, Fiber Optics, MODE, and Energy Efficiency On March 29, 2013, in Concentrating Solar Power, Energy, Partnership, Photovoltaic, Renewable...

  9. Heat pulse propagation in chaotic three-dimensional magnetic fields

    SciTech Connect (OSTI)

    Del-Castillo-Negrete, Diego [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Blazevski, Daniel [Institute for Mechanical Systems, ETH, Zurich (Switzerland)

    2014-06-01T23:59:59.000Z

    Heat pulse propagation in three-dimensional chaotic magnetic fields is studied by numerically solving the parallel heat transport equation using a Lagrangian Green's function (LG) method. The main two problems addressed are: the dependence of the radial transport of heat pulses on the level of magnetic field stochasticity (controlled by the amplitude of the magnetic field perturbation, ?), and the role of reversed shear magnetic field configurations on heat pulse propagation. The role of separatrix reconnection of resonant modes in the shear reversal region, and the role of shearless Cantori in the observed phenomena are also discussed.

  10. Dynamic photorefractivity guided by single-pulse voltage

    SciTech Connect (OSTI)

    Agashkov, A. V., E-mail: agashkov@inel.bas.net.by; Kovalev, A. A. [National Academy of Sciences of Belarus, Institute of Electronics (Belarus); Parka, J. [Military University of Technology, Institute of Applied Physics (Poland)

    2008-03-15T23:59:59.000Z

    The dynamic photorefractivity in a cell with photoconducting orienting layers, filled with a nematic liquid crystal (LC) 6CHBT and a mixture of anthraquinone dyes AD1 and AD2, has been investigated. The single-pulse mode, in which the polarity and amplitude of a dc electric field applied to an LC cell are switched for a fixed time interval, has been used. The scheme of dynamic self-diffraction of low-power laser beams was used in the experiment. The dependences of the width and intensity of diffraction pulses on the bias and switching voltages have been investigated. It is established that the width and intensity of the diffraction pulse arising after initial voltage recovery depends also on the switching pulse width. At the optimal width of the control pulse, the diffraction efficiency increases by two orders of magnitude.

  11. Pulse-mode temperature sensing with langasite SAW devices

    E-Print Network [OSTI]

    Greve, David.W.

    is increasingly important for many industrial processes, such as control of oxy-fuel combustion in several papers with wired gas and temperature sensing demonstrated up to 1000 ºC [7-11], and wireless

  12. Performances of Induction System for Nanosecond Mode Operation

    SciTech Connect (OSTI)

    Krasnykh, Anatoly; /SLAC

    2006-05-16T23:59:59.000Z

    An induction system comprises an array of single turn pulse transformers. Ferromagnetic cores of transformers are toroids that are stacked along the longitudinal core axis. Another name for this array is a fraction transformer or an adder. The primary and secondary windings of such a design have one turn. The step up mode is based on the number of primary pulse sources. The secondary windings are connected in series. Performances of such a system for the nanosecond range mode operation are different in comparison to the performances of traditional multi-turn pulse transformers, which are working on a 100+ nanosecond mode operation. In this paper, the author discusses which aspects are necessary to take into account for the high power nanosecond fractional transformer designs. The engineering method of the nanosecond induction system design is presented.

  13. STUDENT PULSE Spring 2013

    E-Print Network [OSTI]

    SF STATE STUDENT PULSE SURVEY Spring 2013 Academic Planning and Development Academic Institutional Research (air.sfsu.edu) March 2013 #12;SF State Student Pulse Survey, Spring 2013 Page 1 Table of Contents is most effective. 79% of all respondents reported spending most of their time in class listening while

  14. Pulsed electrodeposition. Final report

    SciTech Connect (OSTI)

    Stimetz, C.J.

    1985-02-01T23:59:59.000Z

    Pulse plating of cobalt-hardened gold alloys increases the cobalt content in the alloy. At lower duty cycles, the electrodeposits become dull. Little change in the microhardness was observed between pulsed and direct current electrodeposits. The TEM and electron diffraction analyses indicated no significant difference in microstructure between pulsed and conventional gold alloy electrodeposits. Pulse plated and conventional nickel deposits have been compared for differences in morphology, mechanical properties, and microstructure. The deposits were obtained from nickel sulfamate, nickel chloride, and Watts nickel plating solutions. No significant differences were found in the direct and pulse current deposits from the sulfamate and chloride solutions; however, significant differences in microstructure, yield strength, and microhardness were observed in deposits from the Watts nickel solution.

  15. List mode multichannel analyzer

    DOE Patents [OSTI]

    Archer, Daniel E. (Livermore, CA); Luke, S. John (Pleasanton, CA); Mauger, G. Joseph (Livermore, CA); Riot, Vincent J. (Berkeley, CA); Knapp, David A. (Livermore, CA)

    2007-08-07T23:59:59.000Z

    A digital list mode multichannel analyzer (MCA) built around a programmable FPGA device for onboard data analysis and on-the-fly modification of system detection/operating parameters, and capable of collecting and processing data in very small time bins (<1 millisecond) when used in histogramming mode, or in list mode as a list mode MCA.

  16. Pulsed atmospheric fluidized bed combustion

    SciTech Connect (OSTI)

    Not Available

    1989-11-01T23:59:59.000Z

    In order to verify the technical feasibility of the MTCI Pulsed Atmospheric Fluidized Bed Combustor technology, a laboratory-scale system was designed, built and tested. Important aspects of the operational and performance parameters of the system were established experimentally. A considerable amount of the effort was invested in the initial task of constructing an AFBC that would represent a reasonable baseline against which the performance of the PAFBC could be compared. A summary comparison of the performance and emissions data from the MTCI 2 ft {times} 2 ft facility (AFBC and PAFBC modes) with those from conventional BFBC (taller freeboard and recycle operation) and circulating fluidized bed combustion (CFBC) units is given in Table ES-1. The comparison is for typical high-volatile bituminous coals and sorbents of average reactivity. The values indicated for BFBC and CFBC were based on published information. The AFBC unit that was designed to act as a baseline for the comparison was indeed representative of the larger units even at the smaller scale for which it was designed. The PAFBC mode exhibited superior performance in relation to the AFBC mode. The higher combustion efficiency translates into reduced coal consumption and lower system operating cost; the improvement in sulfur capture implies less sorbent requirement and waste generation and in turn lower operating cost; lower NO{sub x} and CO emissions mean ease of site permitting; and greater steam-generation rate translates into less heat exchange surface area and reduced capital cost. Also, the PAFBC performance generally surpasses those of conventional BFBC, is comparable to CFBC in combustion and NO{sub x} emissions, and is better than CFBC in sulfur capture and CO emissions even at the scaled-down size used for the experimental feasibility tests.

  17. Studies of Charge Exchange in a High?Pressure Pulsed Electron Impact Source

    E-Print Network [OSTI]

    Sharma, D. K. Sen; Hierl, Peter M.; Franklin, J. L.

    1972-01-01T23:59:59.000Z

    A high pressure pulsed ion source has been used in a time?of?flight mass spectrometer in order to study the charge exchangereactions in Ar–H2 and Ar–D2 systems using the ion source in the ?ermák mode of operation. As the source was used in a pulsed...

  18. Pulsed Power for a Dynamic Transmission Electron Microscope

    SciTech Connect (OSTI)

    dehope, w j; browning, n; campbell, g; cook, e; king, w; lagrange, t; reed, b; stuart, b; Shuttlesworth, R; Pyke, B

    2009-06-25T23:59:59.000Z

    Lawrence Livermore National Laboratory (LLNL) has converted a commercial 200kV transmission electron microscope (TEM) into an ultrafast, nanoscale diagnostic tool for material science studies. The resulting Dynamic Transmission Electron Microscope (DTEM) has provided a unique tool for the study of material phase transitions, reaction front analyses, and other studies in the fields of chemistry, materials science, and biology. The TEM's thermionic electron emission source was replaced with a fast photocathode and a laser beam path was provided for ultraviolet surface illumination. The resulting photoelectron beam gives downstream images of 2 and 20 ns exposure times at 100 and 10 nm spatial resolution. A separate laser, used as a pump pulse, is used to heat, ignite, or shock samples while the photocathode electron pulses, carefully time-synchronized with the pump, function as probe in fast transient studies. The device functions in both imaging and diffraction modes. A laser upgrade is underway to make arbitrary cathode pulse trains of variable pulse width of 10-1000 ns. Along with a fast e-beam deflection scheme, a 'movie mode' capability will be added to this unique diagnostic tool. This talk will review conventional electron microscopy and its limitations, discuss the development and capabilities of DTEM, in particularly addressing the prime and pulsed power considerations in the design and fabrication of the DTEM, and conclude with the presentation of a deflector and solid-state pulser design for Movie-Mode DTEM.

  19. Pulse measurement apparatus and method

    DOE Patents [OSTI]

    Marciante, John R. (Webster, NY); Donaldson, William R. (Pittsford, NY); Roides, Richard G. (Scottsville, NY)

    2011-10-25T23:59:59.000Z

    An embodiment of the invention is directed to a pulse measuring system that measures a characteristic of an input pulse under test, particularly the pulse shape of a single-shot, nano-second duration, high shape-contrast optical or electrical pulse. An exemplary system includes a multi-stage, passive pulse replicator, wherein each successive stage introduces a fixed time delay to the input pulse under test, a repetitively-gated electronic sampling apparatus that acquires the pulse train including an entire waveform of each replica pulse, a processor that temporally aligns the replicated pulses, and an averager that temporally averages the replicated pulses to generate the pulse shape of the pulse under test. An embodiment of the invention is directed to a method for measuring an optical or an electrical pulse shape. The method includes the steps of passively replicating the pulse under test with a known time delay, temporally stacking the pulses, and temporally averaging the stacked pulses. An embodiment of the invention is directed to a method for increasing the dynamic range of a pulse measurement by a repetitively-gated electronic sampling device having a rated dynamic range capability, beyond the rated dynamic range of the sampling device; e.g., enhancing the dynamic range of an oscilloscope. The embodied technique can improve the SNR from about 300:1 to 1000:1. A dynamic range enhancement of four to seven bits may be achieved.

  20. Pulse compression in plasma: generation of femtosecond pulses without CPA

    E-Print Network [OSTI]

    ­frequency laser beam into the energy of a short lower­frequency laser pulse. The standard approach to generating high­intensity ultra­short laser pulses is Chirped Pulse Amplification [1] (CPA), in which a laser Garching, Germany Abstract: Laser pulses can be e#ciently compressed to femto­ second duration when

  1. The Theta Laser A Low Noise Chirped Pulse Laser

    E-Print Network [OSTI]

    Van Stryland, Eric

    · Increased laser coherence · Ultra-low noise lasersOC ISO SOA #12;8 Approach Semiconductor-Based FrequencyThe Theta Laser A Low Noise Chirped Pulse Laser Dimitrios Mandridis dmandrid@creol.ucf.edu April 29, 2011 CREOL Affiliates Day 2011 #12;2 Objective: Frequency Swept (FM) Mode-locked Laser · Develop

  2. Schwinger Pair Production in Pulsed Electric Fields

    E-Print Network [OSTI]

    Sang Pyo Kim; Hyung Won Lee; Remo Ruffini

    2012-07-22T23:59:59.000Z

    We numerically investigate the temporal behavior and the structure of longitudinal momentum spectrum and the field polarity effect on pair production in pulsed electric fields in scalar quantum electrodynamics (QED). Using the evolution operator expressed in terms of the particle and antiparticle operators, we find the exact quantum states under the influence of electric pulses and measure the number of pairs of the Minkowski particle and antiparticle. The number of pairs, depending on the configuration of electric pulses, exhibits rich structures in the longitudinal momentum spectrum and undergoes diverse dynamical behaviors at the onset of the interaction but always either converges to a momentum-dependent constant or oscillates around a momentum-dependent time average after the completion of fields.

  3. Drop shaping by laser-pulse impact

    E-Print Network [OSTI]

    Klein, Alexander L; Visser, Claas Willem; Lhuissier, Henri; Sun, Chao; Snoeijer, Jacco H; Villermaux, Emmanuel; Lohse, Detlef; Gelderblom, Hanneke

    2015-01-01T23:59:59.000Z

    We study the hydrodynamic response of a falling drop hit by a laser pulse. Combining high-speed with stroboscopic imaging we report that a millimeter-sized dyed water drop hit by a milli-Joule nanosecond laser-pulse deforms and propels forward at several meters per second, until it eventually fragments. We show that the drop motion results from the recoil momentum imparted at the drop surface by water vaporization. We measure the propulsion speed and the time-deformation law of the drop, complemented by boundary integral simulations. We explain the drop propulsion and shaping in terms of the laser pulse energy and drop surface tension. These findings are crucial for the generation of extreme ultraviolet (EUV) light in lithography machines.

  4. Pulsed Zeeman spectroscopy

    E-Print Network [OSTI]

    Cullen, Raymond Paul

    1967-01-01T23:59:59.000Z

    PULSED ZEEMAN SPECTROSCOPY A Thesis Raymond P. Cullen Submitted to the Graduate Collepe of the Texas MM University in partial fulfillment of the requirements for the degree of MASTER OE SCIENCE August 1967 Major Subject: Chemistry PULSRD... ZEEHA&'I SPRCTPOSC::)Py A The. ", is by Raymond P. Cullen Approved es to style and content by: (Chairman o~ Commi. tee) August 1967 Pulsed Zceman Spectroscopy (August 1967) Raymond P. Cullen, B. S. , Texas A6M University Directed by: Dr...

  5. Pulse magnetic welder

    DOE Patents [OSTI]

    Christiansen, D.W.; Brown, W.F.

    1984-01-01T23:59:59.000Z

    A welder is described for automated closure of fuel pins by a pulsed magnetic process in which the open end of a length of cladding is positioned within a complementary tube surrounded by a pulsed magnetic welder. Seals are provided at each end of the tube, which can be evacuated or can receive tag gas for direct introduction to the cladding interior. Loading of magnetic rings and end caps is accomplished automatically in conjunction with the welding steps carried out within the tube.

  6. Pulse shaping with transmission lines

    DOE Patents [OSTI]

    Wilcox, Russell B. (Oakland, CA)

    1987-01-01T23:59:59.000Z

    A method and apparatus for forming shaped voltage pulses uses passive reflection from a transmission line with nonuniform impedance. The impedance of the reflecting line varies with length in accordance with the desired pulse shape. A high voltage input pulse is transmitted to the reflecting line. A reflected pulse is produced having the desired shape and is transmitted by pulse removal means to a load. Light activated photoconductive switches made of silicon can be utilized. The pulse shaper can be used to drive a Pockels cell to produce shaped optical pulses.

  7. Pulse shaping with transmission lines

    DOE Patents [OSTI]

    Wilcox, R.B.

    1985-08-15T23:59:59.000Z

    A method and apparatus for forming shaped voltage pulses uses passive reflection from a transmission line with nonuniform impedance. The impedance of the reflecting line varies with length in accordance with the desired pulse shape. A high voltage input pulse is transmitted to the reflecting line. A reflected pulse is produced having the desired shape and is transmitted by pulse removal means to a load. Light activated photoconductive switches made of silicon can be utilized. The pulse shaper can be used to drive a Pockels cell to produce shaped optical pulses.

  8. Storage Ring Operation Modes

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Longitudinal bunch profile and Up: APS Storage Ring Parameters Previous: Source Parameter Table Storage Ring Operation Modes Standard Operating Mode, top-up Fill pattern: 102 mA in...

  9. Mode-locking via active gain modulation in quantum cascade lasers

    E-Print Network [OSTI]

    Gkortsas, Vasileios-Marios

    A mode-locking mechanism by active gain modulation is studied numerically and experimentally. The parameter window for the emission of stable pulse trains was found. Pulses as short as 3 ps (~0.5 pJ) were characterized by ...

  10. Magic mode switching in Yb:CaGdAlO4 laser under high pump power

    E-Print Network [OSTI]

    and interesting properties for high- power and ultra-short-pulse lasers. In fact, by combining both broad emission bandwidth and good thermal prop- erties, it permits us to demonstrate ultra-short pulses [1,2] and highMagic mode switching in Yb:CaGdAlO4 laser under high pump power Frédéric Druon,1, * Mickaël Olivier

  11. Efficient optical pulse stacker system

    DOE Patents [OSTI]

    Seppala, Lynn G. (Pleasanton, CA); Haas, Roger A. (Pleasanton, CA)

    1982-01-01T23:59:59.000Z

    Method and apparatus for spreading and angle-encoding each pulse of a multiplicity of small area, short pulses into several temporally staggered pulses by use of appropriate beam splitters, with the optical elements being arranged so that each staggered pulse is contiguous with one or two other such pulses, and the entire sequence of stacked pulses comprising a single, continuous long pulse. The single long pulse is expanded in area, and then doubly passed through a nonstorage laser amplifier such as KrF. After amplification, the physically separated, angle-encoded and temporally staggered pulses are recombined into a single pulse of short duration. This high intensity output beam is well collimated and may be propagated over long distance, or used for irradiating inertial confinement fusion targets.

  12. Identification and Evaluation of Near-term Opportunities for...

    Broader source: Energy.gov (indexed) [DOE]

    and model simulations. Near-term Pathways * Waste-heat recovery - Bottoming cycles - Turbo-compounding - Thermo-electrics * Reduce heat loss - Advanced combustion modes -...

  13. Photoconductive circuit element pulse generator

    DOE Patents [OSTI]

    Rauscher, Christen (Alexandria, VA)

    1989-01-01T23:59:59.000Z

    A pulse generator for characterizing semiconductor devices at millimeter wavelength frequencies where a photoconductive circuit element (PCE) is biased by a direct current voltage source and produces short electrical pulses when excited into conductance by short laser light pulses. The electrical pulses are electronically conditioned to improve the frequency related amplitude characteristics of the pulses which thereafter propagate along a transmission line to a device under test.

  14. Effect of high-voltage nanosecond pulses on complex plasmas

    SciTech Connect (OSTI)

    Pustylnik, M. Y.; Ivlev, A. V.; Thomas, H. M.; Morfill, G. E. [Max-Planck-Institut fuer Extraterrestrische Physik, Giessenbachstrasse, 85741 Garching (Germany); Vasilyak, L. M.; Vetchinin, S. P.; Polyakov, D. N.; Fortov, V. E. [Joint Institute for High Temperatures, Russian Academy of Sciences, Izhorskaya 13/19, 125412 Moscow (Russian Federation)

    2009-11-15T23:59:59.000Z

    Influence of high-voltage (1-11 kV) pulses of nanosecond (20 ns) duration on microparticles levitating in a rf plasma is studied. It is shown that the pulses produce significant influence on the plasma, causing perturbations with the relaxation time of the order of 10{sup -4} s. This time is sufficient for the microparticle to acquire significant kinetic energy. Application of repetitive pulses leads to the vertical oscillations of the microparticles. Clusters, consisting of small number of microparticles, exhibit parametric instabilities of horizontal modes under the effect of repetitive pulses. It was shown that the parametric instability is caused by the vertical oscillations of the microparticles in the nonuniform environment of the sheath.

  15. To Expected Charge Fluctuations Data from the long pulse run 17-Feb-2002

    E-Print Network [OSTI]

    Te if possible - button BPMs equipped with electronics from the undulator - additional stripline BPM BIS long pulse operation mode in analysis mode reentrant BPM Protvino BPM dogleg +vertical steerers stripline BPM button BPMs button BPM beamdump 25 MeV beam, 8mA@10 Hz #12;Resolution of the Injector

  16. Modes of log gravity

    SciTech Connect (OSTI)

    Bergshoeff, Eric A.; Rosseel, Jan [Centre for Theoretical Physics, University of Groningen, Nijenborgh 4, 9747 AG Groningen (Netherlands); Hohm, Olaf [Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Townsend, Paul K. [Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge, CB3 0WA (United Kingdom)

    2011-05-15T23:59:59.000Z

    The physical modes of a recently proposed D-dimensional 'critical gravity', linearized about its anti-de Sitter vacuum, are investigated. All 'log mode' solutions, which we categorize as 'spin-2' or 'Proca', arise as limits of the massive spin-2 modes of the noncritical theory. The linearized Einstein tensor of a spin-2 log mode is itself a 'nongauge' solution of the linearized Einstein equations whereas the linearized Einstein tensor of a Proca mode takes the form of a linearized general coordinate transformation. Our results suggest the existence of a holographically dual logarithmic conformal field theory.

  17. Timing jitter in passively mode-locked semiconductor lasers

    E-Print Network [OSTI]

    Pimenov, A; Rachinskii, D; Hegarty, S P; Huyet, G; Vladimirov, A G

    2014-01-01T23:59:59.000Z

    We study the effect of noise on the dynamics of passively mode-locked semiconductor lasers both experimentally and theoretically. A method combining analytical and numerical approaches for estimation of pulse timing jitter is proposed. We investigate how the presence of dynamical features such as wavelength bistability affects timing jitter.

  18. Self-pulsing of hollow cathode discharge in various gases

    SciTech Connect (OSTI)

    Qin, Y.; He, F., E-mail: hefeng@bit.edu.cn; Jiang, X. X.; Ouyang, J. T., E-mail: jtouyang@bit.edu.cn [School of Physics, Beijing Institute of Technology, Beijing 100081 (China); Xie, K. [School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081 (China)

    2014-07-15T23:59:59.000Z

    In this paper, we investigate the self-pulsing phenomenon of cavity discharge in a cylindrical hollow cathode in various gases including argon, helium, nitrogen, oxygen, and air. The current-voltage characteristics of the cavity discharge, the waveforms of the self-pulsing current and voltage as well as the repetition frequency were measured. The results show that the pulsing frequency ranges from a few to tens kilohertz and depends on the averaged current and the pressure in all gases. The pulsing frequency will increase with the averaged current and decrease with the pressure. The rising time of the current pulse is nearly constant in a given gas or mixture. The self-pulsing does not depend on the external ballast but is affected significantly by the external capacitor in parallel with the discharge cell. The low-current self-pulsing in hollow cathode discharge is the mode transition between Townsend and glow discharges. It can be described by the charging-discharging process of an equivalent circuit consisting of capacitors and resistors.

  19. Laser pulse sampler

    DOE Patents [OSTI]

    Vann, C.

    1998-03-24T23:59:59.000Z

    The Laser Pulse Sampler (LPS) measures temporal pulse shape without the problems of a streak camera. Unlike the streak camera, the laser pulse directly illuminates a camera in the LPS, i.e., no additional equipment or energy conversions are required. The LPS has several advantages over streak cameras. The dynamic range of the LPS is limited only by the range of its camera, which for a cooled camera can be as high as 16 bits, i.e., 65,536. The LPS costs less because there are fewer components, and those components can be mass produced. The LPS is easier to calibrate and maintain because there is only one energy conversion, i.e., photons to electrons, in the camera. 5 figs.

  20. Laser pulse sampler

    DOE Patents [OSTI]

    Vann, Charles (Fremont, CA)

    1998-01-01T23:59:59.000Z

    The Laser Pulse Sampler (LPS) measures temporal pulse shape without the problems of a streak camera. Unlike the streak camera, the laser pulse directly illuminates a camera in the LPS, i.e., no additional equipment or energy conversions are required. The LPS has several advantages over streak cameras. The dynamic range of the LPS is limited only by the range of its camera, which for a cooled camera can be as high as 16 bits, i.e., 65,536. The LPS costs less because there are fewer components, and those components can be mass produced. The LPS is easier to calibrate and maintain because there is only one energy conversion, i.e., photons to electrons, in the camera.

  1. Pulse shaping system

    DOE Patents [OSTI]

    Skeldon, M.D.; Letzring, S.A.

    1999-03-23T23:59:59.000Z

    Temporally shaped electrical waveform generation provides electrical waveforms suitable for driving an electro-optic modulator (EOM) which produces temporally shaped optical laser pulses for inertial confinement fusion (ICF) research. The temporally shaped electrical waveform generation is carried out with aperture coupled transmission lines having an input transmission line and an aperture coupled output transmission line, along which input and output pulses propagate in opposite directions. The output electrical waveforms are shaped principally due to the selection of coupling aperture width, in a direction transverse to the lines, which varies along the length of the line. Specific electrical waveforms, which may be high voltage (up to kilovolt range), are produced and applied to the EOM to produce specifically shaped optical laser pulses. 8 figs.

  2. Pulse shaping system

    DOE Patents [OSTI]

    Skeldon, Mark D. (Penfield, NY); Letzring, Samuel A. (Jemez Springs, NM)

    1999-03-23T23:59:59.000Z

    Temporally shaped electrical waveform generation provides electrical waveforms suitable for driving an electro-optic modulator (EOM) which produces temporally shaped optical laser pulses for inertial confinement fusion (ICF) research. The temporally shaped electrical waveform generation is carried out with aperture coupled transmission lines having an input transmission line and an aperture coupled output transmission line, along which input and output pulses propagate in opposite directions. The output electrical waveforms are shaped principally due to the selection of coupling aperture width, in a direction transverse to the lines, which varies along the length of the line. Specific electrical waveforms, which may be high voltage (up to kilovolt range), are produced and applied to the EOM to produce specifically shaped optical laser pulses.

  3. Pulse power linac

    DOE Patents [OSTI]

    Villa, Francesco (Alameda, CA)

    1990-01-01T23:59:59.000Z

    A linear acceleration for charged particles is constructed of a plurality of transmission line sections that extend between a power injection region and an accelerating region. Each line section is constructed of spaced plate-like conductors and is coupled to an accelerating gap located at the accelerating region. Each gap is formed between a pair of apertured electrodes, with all of the electrode apertures being aligned along a particle accelerating path. The accelerating gaps are arranged in series, and at the injection region the line sections are connected in parallel. At the injection region a power pulse is applied simultaneously to all line sections. The line sections are graduated in length so that the pulse reaches the gaps in a coordinated sequence whereby pulse energy is applied to particles as they reach each of the gaps along the accelerating path.

  4. A pulse processing station

    SciTech Connect (OSTI)

    Morgado, A.M.L.S.; Simoes, J.B.; Landeck, J. [Univ. of Coimbra (Portugal)] [and others

    1996-12-31T23:59:59.000Z

    This is the first of two papers concerning the architecture, circuitry design and performance of a pulse processing system based on a digital signal processor. This multifunction system, implemented as a single PC module, incorporates a high performance 16-bit Pulse Height Analyzer (PHA) a Multichannel Scaler (MCS), a Digital Oscilloscope (DSO) and also a Digital Pulse Processor (DPP). This paper presents the PRA architecture with emphasis on the baseline restorer and peak stretcher circuits. Differential nonlinearities (DNL) are corrected by a new implementation of the sliding scale technique and performance ranges from better than 2% (at 16-bit resolution) up to less than 0.2% for 12-bit operation. The DNL correction technique is assessed for different sliding-scale ranges.

  5. Pulsed neutron detector

    DOE Patents [OSTI]

    Robertson, deceased, J. Craig (late of Albuquerque, NM); Rowland, Mark S. (Livermore, CA)

    1989-03-21T23:59:59.000Z

    A pulsed neutron detector and system for detecting low intensity fast neutron pulses has a body of beryllium adjacent a body of hydrogenous material the latter of which acts as a beta particle detector, scintillator, and moderator. The fast neutrons (defined as having En>1.5 MeV) react in the beryllium and the hydrogenous material to produce larger numbers of slow neutrons than would be generated in the beryllium itself and which in the beryllium generate hellium-6 which decays and yields beta particles. The beta particles reach the hydrogenous material which scintillates to yield light of intensity related to the number of fast neutrons. A photomultiplier adjacent the hydrogenous material (scintillator) senses the light emission from the scintillator. Utilization means, such as a summing device, sums the pulses from the photo-multiplier for monitoring or other purposes.

  6. Slow-light propagation using mode locking of spin precession in quantum dots

    SciTech Connect (OSTI)

    Shabaev, A. [George Mason University, Fairfax Virginia 22030 (United States); Dutton, Z. [Raytheon BBN Technologies, 10 Moulton Street, Cambridge, Massachusetts 02138 (United States); Naval Research Laboratory, Washington, D.C. 20375 (United States); Kennedy, T. A.; Efros, Al. L. [Naval Research Laboratory, Washington, D.C. 20375 (United States)

    2010-11-15T23:59:59.000Z

    We propose using mode locking to enable coherent nonlinear optical effects in inhomogenously broadened spin ensembles. We carry out detailed calculations for quantum dot systems in which increased spin coherence via mode locking has been recently observed [A. Greilich et al., Science 313, 341 (2006); 317, 1896 (2007)]. We show how, in the presence of spin locking, a strong pulse-matching effect occurs, providing a powerful tool for high-bandwidth linear optical processing. We then go on to study 'slow light' in this system and show that high-bandwidth pulses can be controllably delayed by a time comparable to the pulse width.

  7. SNMR pulse sequence phase cycling

    DOE Patents [OSTI]

    Walsh, David O; Grunewald, Elliot D

    2013-11-12T23:59:59.000Z

    Technologies applicable to SNMR pulse sequence phase cycling are disclosed, including SNMR acquisition apparatus and methods, SNMR processing apparatus and methods, and combinations thereof. SNMR acquisition may include transmitting two or more SNMR pulse sequences and applying a phase shift to a pulse in at least one of the pulse sequences, according to any of a variety cycling techniques. SNMR processing may include combining SNMR from a plurality of pulse sequences comprising pulses of different phases, so that desired signals are preserved and indesired signals are canceled.

  8. Fields of an ultrashort tightly-focused laser pulse

    E-Print Network [OSTI]

    Li, Jian-Xing; Hatsagortsyan, Karen Z; Keitel, Christoph H

    2015-01-01T23:59:59.000Z

    Analytic expressions for the electromagnetic fields of an ultrashort, tightly focused, laser pulse in vacuum are derived from scalar and vector potentials, using on equal footing two small parameters connected with the waist size of the laser beam and its duration. Compared with fields derived from a complex-source-point approach and a Lax series expansion approach, the derived fields are shown to be well-behaved and accurate even in the subcycle pulse regime. Terms stemming from the scalar potential are shown to be non-negligible and could significantly influence laser-matter interactions, in particular, direct electron acceleration in vacuum by an ultrashort laser pulse.

  9. Multi-mode Damage Detection Methods with Piezoelectric Wafer Active Sensors

    E-Print Network [OSTI]

    Giurgiutiu, Victor

    impedance measurements; (3) PWAS ultrasonic SHM/NDE; and (4) PWAS multi-mode corrosion detection multiple modes in situ SHM methods using PWAS transducers with impedance, pitch- catch, and/or pulse transducers for impedance measure- ment and ultrasonic inspection are given first. Then several examples

  10. Different generation regimes of mode-locked all-positive-dispersion all-fiber Yb laser

    E-Print Network [OSTI]

    Kobtsev, Sergei M.

    to achieve stable mode-locking and ultra-short pulse generation in an all-positive dispersion cavityDifferent generation regimes of mode-locked all-positive-dispersion all-fiber Yb laser Sergey Kobtseva , Sergey Kukarina , Sergey Smirnova , Sergey Turitsynb , Anton Latkina a Laser system laboratory

  11. The polarization field for pulsed Raman transitions

    SciTech Connect (OSTI)

    Shore, B.W.; Sacks, R.; Karr, T.

    1987-05-15T23:59:59.000Z

    This memo discusses the induced polarization field that occurs in the presence of Raman processes, and the propagation equations that result from this field. First the paper summarizes the relationship between the macroscopic polarization field and the microscopic dipole-moment expectation value. It summarizes expressions for the induced dipole moment that result from the adiabatic elimination of non-resonant molecular transitions, to produce an effective two-photon (Raman) Hamiltonian. Then it shows that the polarization field has a similar mode expansion to the electric field. Using this result the equations for pulse propagation of the electric field are described. These equations involve a generalized gain matrix and mode velocity, as well as a refractive index, each of which depends upon position and time. Finally the paper summarizes these results and exhibits succinctly the pulse propagation equations in the plane-wave slowly-varying envelope approximation. The equations presented here must be supplemented with excitation equations (or by steady-state results) for the molecules. The material presented here is a portion of a more extensive treatment of propagation to be presented separately.

  12. Mixed-mode cooling.

    E-Print Network [OSTI]

    Brager, Gail

    2006-01-01T23:59:59.000Z

    ASHRAE’s permission. Mixed-Mode Cooling Photo Credit: Paulnatural ventilation for cooling. Buildings typically had1950s of large-scale mechanical cooling, along with other

  13. Large energy soliton erbium-doped fiber laser with a graphene-polymer composite mode locker

    E-Print Network [OSTI]

    Han Zhang; Qiaoliang Bao; Dingyuan Tang; Luming Zhao; Kianping Loh

    2009-09-30T23:59:59.000Z

    Due to its unique electronic property and the Pauli Blocking Principle, atomic layer graphene possesses wavelength-independent ultrafast saturable absorption, which can be exploited for the ultrafast photonics application. Through chemical functionalization, a graphene-polymer nanocomposite membrane was fabricated and firstly used to mode lock a fiber laser. Stable mode locked solitons with 3 nJ pulse energy, 700 fs pulse width at the 1590 nm wavelength have been directly generated from the laser. We show that graphene-polymer nanocomposites could be an attractive saturable absorber for high power fiber laser mode locking.

  14. 190-fs passively mode-locked thulium fiber laser with a low threshold

    SciTech Connect (OSTI)

    Sharp, R.C.; Spock, D.E.; Pan, N.; Elliot, J. [Raytheon Company, Electronic Systems, 131 Spring Street, Lexington, Massachusetts 02173 (United States)

    1996-06-01T23:59:59.000Z

    We report a self-starting passively mode-locked thulium-doped silica fiber laser capable of 190-fs pulses. This practical, compact package is driven by a single 50-mW passively cooled diode laser, has a launched pump-power threshold of 18 mW for mode locking, and produces a 50-MHz train of mode-locked 20-pJ pulses at a wavelength near 1.9 {mu}m. {copyright} {ital 1996 Optical Society of America.}

  15. Sequentially pulsed traveling wave accelerator

    DOE Patents [OSTI]

    Caporaso, George J. (Livermore, CA); Nelson, Scott D. (Patterson, CA); Poole, Brian R. (Tracy, CA)

    2009-08-18T23:59:59.000Z

    A sequentially pulsed traveling wave compact accelerator having two or more pulse forming lines each with a switch for producing a short acceleration pulse along a short length of a beam tube, and a trigger mechanism for sequentially triggering the switches so that a traveling axial electric field is produced along the beam tube in synchronism with an axially traversing pulsed beam of charged particles to serially impart energy to the particle beam.

  16. Instrument performance study on the short and long pulse options of the second Spallation Neutron Source target station

    SciTech Connect (OSTI)

    Zhao, J. K.; Herwig, Kenneth W.; Robertson, J. L.; Gallmeier, Franz X.; Riemer, Bernard W. [Instrument and Source Division, Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)] [Instrument and Source Division, Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

    2013-10-15T23:59:59.000Z

    The Spallation Neutron Source (SNS) facility at the Oak Ridge National Laboratory is designed with an upgrade option for a future low repetition rate, long wavelength second target station. This second target station is intended to complement the scientific capabilities of the 1.4 MW, 60 Hz high power first target station. Two upgrade possibilities have been considered, the short and the long pulse options. In the short pulse mode, proton extraction occurs after the pulse compression in the accumulator ring. The proton pulse structure is thus the same as that for the first target station with a pulse width of ?0.7 ?s. In the long pulse mode, protons are extracted as they are produced by the linac, with no compression in the accumulator ring. The time width of the uncompressed proton pulse is ?1 ms. This difference in proton pulse structure means that neutron pulses will also be different. Neutron scattering instruments thus have to be designed and optimized very differently for these two source options which will directly impact the overall scientific capabilities of the SNS facility. In order to assess the merits of the short and long pulse target stations, we investigated a representative suit of neutron scattering instruments and evaluated their performance under each option. Our results indicate that the short pulse option will offer significantly better performance for the instruments and is the preferred choice for the SNS facility.

  17. Architecture AddressingModes

    E-Print Network [OSTI]

    Nguyen, Dat H.

    MIPS R2000 Architecture and Assembly (Part 1) 1. CPU Registers 2. Byte Order 3. AddressingModes 4­endian byte order 3 2 1 0 0 1 2 3 Or Byte number #12; AddressingModes . MIPS is a load/store architecture . RICS -- Load/Store architecture -- All instructions have equal length of 4 bytes -- Every register can

  18. Zero-mode waveguides

    DOE Patents [OSTI]

    Levene, Michael J.; Korlach, Jonas; Turner, Stephen W.; Craighead, Harold G.; Webb, Watt W.

    2007-02-20T23:59:59.000Z

    The present invention is directed to a method and an apparatus for analysis of an analyte. The method involves providing a zero-mode waveguide which includes a cladding surrounding a core where the cladding is configured to preclude propagation of electromagnetic energy of a frequency less than a cutoff frequency longitudinally through the core of the zero-mode waveguide. The analyte is positioned in the core of the zero-mode waveguide and is then subjected, in the core of the zero-mode waveguide, to activating electromagnetic radiation of a frequency less than the cut-off frequency under conditions effective to permit analysis of the analyte in an effective observation volume which is more compact than if the analysis were carried out in the absence of the zero-mode waveguide.

  19. International magnetic pulse compression workshop: (Proceedings)

    SciTech Connect (OSTI)

    Kirbie, H.C.; Newton, M.A.; Siemens, P.D.

    1991-04-01T23:59:59.000Z

    A few individuals have tried to broaden the understanding of specific and salient pulsed-power topics. One such attempt is this documentation of a workshop on magnetic switching as it applies primarily to pulse compression (power transformation), affording a truly international perspective by its participants under the initiative and leadership of Hugh Kirbie and Mark Newton of the Lawrence Livermore National Laboratory (LLNL) and supported by other interested organizations. During the course of the Workshop at Granlibakken, a great deal of information was amassed and a keen insight into both the problems and opportunities as to the use of this switching approach was developed. The segmented workshop format proved ideal for identifying key aspects affecting optimum performance in a variety of applications. Individual groups of experts addressed network and system modeling, magnetic materials, power conditioning, core cooling and dielectrics, and finally circuits and application. At the end, they came together to consolidate their input and formulate the workshop's conclusions, identifying roadblocks or suggesting research projects, particularly as they apply to magnetic switching's trump card--its high-average-power-handling capability (at least on a burst-mode basis). The workshop was especially productive both in the quality and quantity of information transfer in an environment conducive to a free and open exchange of ideas. We will not delve into the organization proper of this meeting, rather we wish to commend to the interested reader this volume, which provides the definitive and most up-to-date compilation on the subject of magnetic pulse compression from underlying principles to current state of the art as well as the prognosis for the future of magnetic pulse compression as a consensus of the workshop's organizers and participants.

  20. Laser pulse detector

    DOE Patents [OSTI]

    Mashburn, Douglas N. (Knoxville, TN); Akerman, M. Alfred (Knoxville, TN)

    1981-01-01T23:59:59.000Z

    A laser pulse detector is provided which is small and inexpensive and has the capability of detecting laser light of any wavelength with fast response (less than 5 nanoseconds rise time). The laser beam is focused onto the receiving end of a graphite rod coaxially mounted within a close-fitting conductive, open-end cylindrical housing so that ablation and electric field breakdown of the resulting plasma occurs due to a bias potential applied between the graphite rod and housing. The pulse produced by the breakdown is transmitted through a matched impedance coaxial cable to a recording device. The cable is connected with its central lead to the graphite rod and its outer conductor to the housing.

  1. Exploring Ramsey-coherent population trapping atomic clock realized with pulsed microwave modulated laser

    SciTech Connect (OSTI)

    Yang, Jing; Yun, Peter [Key Laboratory of Atomic Frequency Standards, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China); Tian, Yuan; Tan, Bozhong [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074 (China); Gu, Sihong, E-mail: shgu@wipm.ac.cn [Key Laboratory of Atomic Frequency Standards, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China); Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2014-03-07T23:59:59.000Z

    A scheme for a Ramsey-coherent population trapping (CPT) atomic clock that eliminates the acousto-optic modulator (AOM) is proposed and experimentally studied. Driven by a periodically microwave modulated current, the vertical-cavity surface-emitting laser emits a continuous beam that switches between monochromatic and multichromatic modes. Ramsey-CPT interference has been studied with this mode-switching beam. In eliminating the AOM, which is used to generate pulsed laser in conventional Ramsey-CPT atomic clock, the physics package of the proposed scheme is virtually the same as that of a conventional compact CPT atomic clock, although the resource budget for the electronics will slightly increase as a microwave switch should be added. By evaluating and comparing experimentally recorded signals from the two Ramsey-CPT schemes, the short-term frequency stability of the proposed scheme was found to be 46% better than the scheme with AOM. The experimental results suggest that the implementation of a compact Ramsey-CPT atomic clock promises better frequency stability.

  2. Ptychographic ultrafast pulse reconstruction

    E-Print Network [OSTI]

    Spangenberg, D; Brügmann, M H; Feurer, T

    2014-01-01T23:59:59.000Z

    We demonstrate a new ultrafast pulse reconstruction modality which is somewhat reminiscent of frequency resolved optical gating but uses a modified setup and a conceptually different reconstruction algorithm that is derived from ptychography. Even though it is a second order correlation scheme it shows no time ambiguity. Moreover, the number of spectra to record is considerably smaller than in most other related schemes which, together with a robust algorithm, leads to extremely fast convergence of the reconstruction.

  3. Petawatt pulsed-power accelerator

    DOE Patents [OSTI]

    Stygar, William A. (Albuquerque, NM); Cuneo, Michael E. (Albuquerque, NM); Headley, Daniel I. (Albuquerque, NM); Ives, Harry C. (Albuquerque, NM); Ives, legal representative; Berry Cottrell (Albuquerque, NM); Leeper, Ramon J. (Albuquerque, NM); Mazarakis, Michael G. (Albuquerque, NM); Olson, Craig L. (Albuquerque, NM); Porter, John L. (Sandia Park, NM); Wagoner; Tim C. (Albuquerque, NM)

    2010-03-16T23:59:59.000Z

    A petawatt pulsed-power accelerator can be driven by various types of electrical-pulse generators, including conventional Marx generators and linear-transformer drivers. The pulsed-power accelerator can be configured to drive an electrical load from one- or two-sides. Various types of loads can be driven; for example, the accelerator can be used to drive a high-current z-pinch load. When driven by slow-pulse generators (e.g., conventional Marx generators), the accelerator comprises an oil section comprising at least one pulse-generator level having a plurality of pulse generators; a water section comprising a pulse-forming circuit for each pulse generator and a level of monolithic triplate radial-transmission-line impedance transformers, that have variable impedance profiles, for each pulse-generator level; and a vacuum section comprising triplate magnetically insulated transmission lines that feed an electrical load. When driven by LTD generators or other fast-pulse generators, the need for the pulse-forming circuits in the water section can be eliminated.

  4. Laser beam pulse formatting method

    DOE Patents [OSTI]

    Daly, T.P.; Moses, E.I.; Patterson, R.W.; Sawicki, R.H.

    1994-08-09T23:59:59.000Z

    A method for formatting a laser beam pulse using one or more delay loops is disclosed. The delay loops have a partially reflective beam splitter and a plurality of highly reflective mirrors arranged such that the laser beam pulse enters into the delay loop through the beam splitter and circulates therein along a delay loop length defined by the mirrors. As the laser beam pulse circulates within the delay loop a portion thereof is emitted upon each completed circuit when the laser beam pulse strikes the beam splitter. The laser beam pulse is thereby formatted into a plurality of sub-pulses. The delay loops are used in combination to produce complex waveforms by combining the sub-pulses using additive waveform synthesis. 8 figs.

  5. Perturbations of Weakly Resonant Power System Electromechanical Modes

    E-Print Network [OSTI]

    instability. Index Terms-- power system dynamic stability, oscillations, resonance, root loci, eigenvalues of the system linearization and its associated eigenvector. Since the modes determine the power system stability1 Perturbations of Weakly Resonant Power System Electromechanical Modes Ian Dobson, Senior Member

  6. High-speed pulse-shape generator, pulse multiplexer

    DOE Patents [OSTI]

    Burkhart, Scott C. (Livermore, CA)

    2002-01-01T23:59:59.000Z

    The invention combines arbitrary amplitude high-speed pulses for precision pulse shaping for the National Ignition Facility (NIF). The circuitry combines arbitrary height pulses which are generated by replicating scaled versions of a trigger pulse and summing them delayed in time on a pulse line. The combined electrical pulses are connected to an electro-optic modulator which modulates a laser beam. The circuit can also be adapted to combine multiple channels of high speed data into a single train of electrical pulses which generates the optical pulses for very high speed optical communication. The invention has application in laser pulse shaping for inertial confinement fusion, in optical data links for computers, telecommunications, and in laser pulse shaping for atomic excitation studies. The invention can be used to effect at least a 10.times. increase in all fiber communication lines. It allows a greatly increased data transfer rate between high-performance computers. The invention is inexpensive enough to bring high-speed video and data services to homes through a super modem.

  7. Diffraction mode terahertz tomography

    DOE Patents [OSTI]

    Ferguson, Bradley; Wang, Shaohong; Zhang, Xi-Cheng

    2006-10-31T23:59:59.000Z

    A method of obtaining a series of images of a three-dimensional object. The method includes the steps of transmitting pulsed terahertz (THz) radiation through the entire object from a plurality of angles, optically detecting changes in the transmitted THz radiation using pulsed laser radiation, and constructing a plurality of imaged slices of the three-dimensional object using the detected changes in the transmitted THz radiation. The THz radiation is transmitted through the object as a two-dimensional array of parallel rays. The optical detection is an array of detectors such as a CCD sensor.

  8. Standard Terms and Conditions | NREL

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of ScienceandMesa del Sol HomeFacebookScholarshipSpiraling Laser Pulses Could VideoAboutStandard Terms

  9. The electron geodesic acoustic mode

    SciTech Connect (OSTI)

    Chakrabarti, N. [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Calcutta 700 064 (India); Guzdar, P. N. [Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742 (United States); Kaw, P. K. [Institute for Plasma Research Bhat, Gandhinagar 382428 (India)

    2012-09-15T23:59:59.000Z

    In this report, a novel new mode, named the electron geodesic acoustic mode, is presented. This mode can occur in toroidal plasmas like the conventional geodesic acoustic mode (GAM). The frequency of this new mode is much larger than that of the conventional GAM by a factor equal to the square root of the ion to electron mass ratio.

  10. Pulse transformer R and D for NLC klystron pulse modulator

    SciTech Connect (OSTI)

    Akemoto, M.; Gold, S.; Krasnykh, A.; Koontz, R.

    1997-07-01T23:59:59.000Z

    The authors have studied a conventional pulse transformer for the NLC klystron pulse modulator. The transformer has been analyzed using a simplified lumped circuit model. It is found that a fast rise time requires low leakage inductance and low distributed capacitance and can be realized by reducing the number of secondary turns, but it produces larger pulse droop and requires a larger core size. After making a tradeoff among these parameters carefully, a conventional pulse transformer with a rise time of 250ns and a pulse droop of 3.6% has been designed and built. The transmission characteristics and pulse time-response were measured. The data were compared with the model. The agreement with the model was good when the measured values were used in the model simulation. The results of the high voltage tests using a klystron load are also presented.

  11. Development of the pulse transformer for NLC klystron pulse modulator

    SciTech Connect (OSTI)

    Akemoto, M.; Gold, S.; Koontz, R.; Krasnykh, A.

    1997-05-01T23:59:59.000Z

    We have studied a conventional pulse transformer for the NLC klystron pulse modulator. The transformer has been analyzed using a simplified lumped circuit model. It is found that a fast rise time requires low leakage inductance and low distributed capacitance and can be realized by reducing the number of secondary turns, but it produces larger pulse droop and core size. After making a tradeoff among these parameters carefully, a conventional pulse transformer with a rise time of 250ns and pulse droop of 3.6% has been designed and built. The transmission characteristics and pulse time-response were measured. The data were compared with the model. The agreement with the model was good when the measured values were used in the model simulation. The results of the high voltage tests are also presented.

  12. Coiled transmission line pulse generators

    DOE Patents [OSTI]

    McDonald, Kenneth Fox (Columbia, MO)

    2010-11-09T23:59:59.000Z

    Methods and apparatus are provided for fabricating and constructing solid dielectric "Coiled Transmission Line" pulse generators in radial or axial coiled geometries. The pour and cure fabrication process enables a wide variety of geometries and form factors. The volume between the conductors is filled with liquid blends of monomers, polymers, oligomers, and/or cross-linkers and dielectric powders; and then cured to form high field strength and high dielectric constant solid dielectric transmission lines that intrinsically produce ideal rectangular high voltage pulses when charged and switched into matched impedance loads. Voltage levels may be increased by Marx and/or Blumlein principles incorporating spark gap or, preferentially, solid state switches (such as optically triggered thyristors) which produce reliable, high repetition rate operation. Moreover, these Marxed pulse generators can be DC charged and do not require additional pulse forming circuitry, pulse forming lines, transformers, or an a high voltage spark gap output switch. The apparatus accommodates a wide range of voltages, impedances, pulse durations, pulse repetition rates, and duty cycles. The resulting mobile or flight platform friendly cylindrical geometric configuration is much more compact, light-weight, and robust than conventional linear geometries, or pulse generators constructed from conventional components. Installing additional circuitry may accommodate optional pulse shape improvements. The Coiled Transmission Lines can also be connected in parallel to decrease the impedance, or in series to increase the pulse length.

  13. Long Pulse EBW Start-up Experiments in MAST

    E-Print Network [OSTI]

    Shevchenko, V F; Caughman, J B; Diem, S; Mailloux, J; Brien, M R O; Peng, M; Saveliev, A N; Takase, Y; Tanaka, H; Taylor, G

    2015-01-01T23:59:59.000Z

    The non-solenoid start-up technique reported here relies on a double mode conversion for electron Bernstein wave (EBW) excitation. It consists of the mode conversion of the ordinary mode, entering the plasma from the low field side of the tokamak, into the extraordinary (X) mode at a mirror-polarizer located at the high field side. The X mode propagates back to the plasma, passes through electron cyclotron resonance and experiences a subsequent X to EBW mode conversion near the upper hybrid resonance. Finally the excited EBW mode is totally absorbed at the Doppler shifted electron cyclotron resonance. The absorption of EBW remains high even in cold rarefied plasmas. Furthermore, EBW can generate significant plasma current giving the prospect of a fully solenoid-free plasma start-up. First experiments using this scheme were carried out on MAST [V. Shevchenko et al, Nuclear Fusion 50, 022004 (2010)]. Plasma currents up to 33 kA have been achieved using 28 GHz 100kW 90ms RF pulses. Recently experimental results ...

  14. Precision lifetime measurements of a single trapped ion with ultrafast laser pulses D. L. Moehring,* B. B. Blinov, D. W. Gidley, R. N. Kohn, Jr., M. J. Madsen, T. D. Sanderson, R. S. Vallery, and C. Monroe

    E-Print Network [OSTI]

    Blinov, Boris

    Precision lifetime measurements of a single trapped ion with ultrafast laser pulses D. L. Moehring and ultrafast laser technologies, the ion is excited with picosecond laser pulses from a mode-locked laser excited state lifetime of order nanoseconds by an ultrafast laser pulse duration of order picoseconds

  15. 2258 IEEE TRANSACTIONS ON MAGNETICS, VOL. 33, NO. 3, MAY 1997 Pulsed Eddy-Current Response

    E-Print Network [OSTI]

    Bowler, John R.

    2258 IEEE TRANSACTIONS ON MAGNETICS, VOL. 33, NO. 3, MAY 1997 Pulsed Eddy-Current Response to a Conducting Half-Space John Bowler, Member, IEEE, and Marcus Johnson Abstract-- Eddy-current nondestructive agreement between theory and experiment. Index Terms--Eddy current, half-space, pulsed, transient. I

  16. Classical and Quantum Dynamics of Free Electromagnetic Laser Pulses

    E-Print Network [OSTI]

    Goto, S; Walton, T J

    2015-01-01T23:59:59.000Z

    We discuss the use of a class of exact finite energy solutions to the vacuum source free Maxwell equations as models for multi- and single cycle laser pulses in classical interaction with relativistic charged point particles. These solutions are classified in terms of their chiral content and their influence on particular charge configurations in space. The results of such classical interactions motivate a particular quantum description of a freely propagating laser pulse in terms of an effective quantum Hamiltonian. The classical chiral states that evolve according to the classical vacuum Maxwell equations are now replaced by quantized bi-qutrit elements satisfying the Schrodinger equation. This description may offer a means to control and manipulate qu-trit states encoded into such laser pulses.

  17. Transverse-modal behavior of a transverse junction stripe laser excited by a short electrical pulse

    SciTech Connect (OSTI)

    Lau, K.Y.; Yariv, A.

    1981-02-01T23:59:59.000Z

    The transverse-modal behavior of a lateral injection gain-guided laser (the transverse junction strip (TJS) laser) excited by a short (70 ps) electrical pulse is investigated experimentally and theoretically. It is predicted theoretically and observed experimentally that the transverse mode strongly depends on the excitation pulse amplitude and the dc bias current (which is set below threshold). This dependence is found to be due to transient lateral carrier diffusion at the lasing junction.

  18. Controlled light localisation and nonlinear-optical interactions of short laser pulses in holey fibres

    SciTech Connect (OSTI)

    Fedotov, Andrei B; Zheltikov, Aleksei M; Golovan', Leonid A; Kashkarov, Pavel K [Department of Physics, M.V. Lomonosov Moscow State University, Moscow (Russian Federation); Tarasevitch, A P; Podshivalov, Alexey A [International Laser Center, M. V. Lomonosov Moscow State University, Moscow (Russian Federation); Alfimov, Mikhail V; Ivanov, Anatoliy A [Photochemistry Center, Russian Academy of Sciences, Moscow (Russian Federation); Beloglazov, V I [Institute of Technology and Processing of Glass Structures, Russian Academy of Sciences, Saratov (Russian Federation); Haus, J W [University of Dayton, Dayton, OH (United States); Linde, D von der [Institut fur Laser- und Plasmaphysik, Universitat Essen, Essen (Germany)

    2001-05-31T23:59:59.000Z

    The influence of the structure of holey-fibre cladding on the effective waveguide mode area and the spectral broadening of femtosecond pulses of titanium-sapphire and forsterite lasers is experimentally studied. These experiments demonstrate that the increase in the air-filling fraction of the holey-fibre cladding may substantially enhance the spectral broadening of laser pulses due to the increase in the degree of light localisation in the fibre core. (femtosecond technologies)

  19. Green Light Pulse Oximeter

    DOE Patents [OSTI]

    Scharf, John Edward (Oldsmar, FL)

    1998-11-03T23:59:59.000Z

    A reflectance pulse oximeter that determines oxygen saturation of hemoglobin using two sources of electromagnetic radiation in the green optical region, which provides the maximum reflectance pulsation spectrum. The use of green light allows placement of an oximetry probe at central body sites (e.g., wrist, thigh, abdomen, forehead, scalp, and back). Preferably, the two green light sources alternately emit light at 560 nm and 577 nm, respectively, which gives the biggest difference in hemoglobin extinction coefficients between deoxyhemoglobin, RHb, and oxyhemoglobin, HbO.sub.2.

  20. Short-Pulse Lasers

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOnItemResearch > TheNuclearHomelandMultivariate Metal-OrganicPulse Beam Transport Tube

  1. Long Pulse Fusion Physics Experiments Without Superconducting Electromagnets

    E-Print Network [OSTI]

    without any refrigeration system), the consequent ``room temperature'' magnet operation can require of fusion, so near­term superconducting experience may not ultimately be useful. High magnetic field copper magnet heating. Pulse length is thus independent of device size and is easily extended. This scheme

  2. Long Pulse Fusion Physics Experiments Without Superconducting Electromagnets

    E-Print Network [OSTI]

    without any refrigeration system), the consequent "room temperature" magnet operation can require a costly of fusion, so near-term superconducting experience may not ultimately be useful. High magnetic field copper magnet heating. Pulse length is thus independent of device size and is easily extended. This scheme

  3. Pulsed helium ionization detection system

    DOE Patents [OSTI]

    Ramsey, R.S.; Todd, R.A.

    1985-04-09T23:59:59.000Z

    A helium ionization detection system is provided which produces stable operation of a conventional helium ionization detector while providing improved sensitivity and linearity. Stability is improved by applying pulsed dc supply voltage across the ionization detector, thereby modifying the sampling of the detectors output current. A unique pulse generator is used to supply pulsed dc to the detector which has variable width and interval adjust features that allows up to 500 V to be applied in pulse widths ranging from about 150 nsec to about dc conditions.

  4. Pulsed helium ionization detection system

    DOE Patents [OSTI]

    Ramsey, Roswitha S. (Knoxville, TN); Todd, Richard A. (Knoxville, TN)

    1987-01-01T23:59:59.000Z

    A helium ionization detection system is provided which produces stable operation of a conventional helium ionization detector while providing improved sensitivity and linearity. Stability is improved by applying pulsed dc supply voltage across the ionization detector, thereby modifying the sampling of the detectors output current. A unique pulse generator is used to supply pulsed dc to the detector which has variable width and interval adjust features that allows up to 500 V to be applied in pulse widths ranging from about 150 nsec to about dc conditions.

  5. LANSCE | News & Media | The Pulse

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    The Pulse September 2012 September | In This Issue From Alex's desk Biennial national neutron scattering conference features strong Lujan Center presence Development of high...

  6. Fast pulse nonthermal plasma reactor

    DOE Patents [OSTI]

    Rosocha, Louis A.

    2005-06-14T23:59:59.000Z

    A fast pulsed nonthermal plasma reactor includes a discharge cell and a charging assembly electrically connected thereto. The charging assembly provides plural high voltage pulses to the discharge cell. Each pulse has a rise time between one and ten nanoseconds and a duration of three to twenty nanoseconds. The pulses create nonthermal plasma discharge within the discharge cell. Accordingly, the nonthermal plasma discharge can be used to remove pollutants from gases or break the gases into smaller molecules so that they can be more efficiently combusted.

  7. Bipolar pulse forming line

    DOE Patents [OSTI]

    Rhodes, Mark A. (Pleasanton, CA)

    2008-10-21T23:59:59.000Z

    A bipolar pulse forming transmission line module for linear induction accelerators having first, second, third, fourth, and fifth planar conductors which form an interleaved stack with dielectric layers between the conductors. Each conductor has a first end, and a second end adjacent an acceleration axis. The first and second planar conductors are connected to each other at the second ends, the fourth and fifth planar conductors are connected to each other at the second ends, and the first and fifth planar conductors are connected to each other at the first ends via a shorting plate adjacent the first ends. The third planar conductor is electrically connectable to a high voltage source, and an internal switch functions to short a high voltage from the first end of the third planar conductor to the first end of the fourth planar conductor to produce a bipolar pulse at the acceleration axis with a zero net time integral. Improved access to the switch is enabled by an aperture through the shorting plate and the proximity of the aperture to the switch.

  8. Switching power pulse system

    DOE Patents [OSTI]

    Aaland, K.

    1983-08-09T23:59:59.000Z

    A switching system for delivering pulses of power from a source to a load using a storage capacitor charged through a rectifier, and maintained charged to a reference voltage level by a transistor switch and voltage comparator. A thyristor is triggered to discharge the storage capacitor through a saturable reactor and fractional turn saturable transformer having a secondary to primary turn ratio N of n:l/n = n[sup 2]. The saturable reactor functions as a soaker'' while the thyristor reaches saturation, and then switches to a low impedance state. The saturable transformer functions as a switching transformer with high impedance while a load coupling capacitor charges, and then switches to a low impedance state to dump the charge of the storage capacitor into the load through the coupling capacitor. The transformer is comprised of a multilayer core having two secondary windings tightly wound and connected in parallel to add their output voltage and reduce output inductance, and a number of single turn windings connected in parallel at nodes for the primary winding, each single turn winding linking a different one of the layers of the multilayer core. The load may be comprised of a resistive beampipe for a linear particle accelerator and capacitance of a pulse forming network. To hold off discharge of the capacitance until it is fully charged, a saturable core is provided around the resistive beampipe to isolate the beampipe from the capacitance until it is fully charged. 5 figs.

  9. Compensated pulsed alternator

    DOE Patents [OSTI]

    Weldon, William F. (Austin, TX); Driga, Mircea D. (Austin, TX); Woodson, Herbert H. (Austin, TX)

    1980-01-01T23:59:59.000Z

    This invention relates to an electromechanical energy converter with inertial energy storage. The device, a single phase, two or multi-pole alternator with stationary field coils, and a rotating armature is provided. The rotor itself may be of laminated steel for slower pulses or for faster pulses should be nonmagnetic and electrically nonconductive in order to allow rapid penetration of the field as the armature coil rotates. The armature coil comprises a plurality of power generating conductors mounted on the rotor. The alternator may also include a stationary or counterrotating compensating coil to increase the output voltage thereof and to reduce the internal impedance of the alternator at the moment of peak outout. As the machine voltage rises sinusoidally, an external trigger switch is adapted to be closed at the appropriate time to create the desired output current from said alternator to an external load circuit, and as the output current passes through zero a self-commutating effect is provided to allow the switch to disconnect the generator from the external circuit.

  10. High Average Power, High Energy Short Pulse Fiber Laser System

    SciTech Connect (OSTI)

    Messerly, M J

    2007-11-13T23:59:59.000Z

    Recently continuous wave fiber laser systems with output powers in excess of 500W with good beam quality have been demonstrated [1]. High energy, ultrafast, chirped pulsed fiber laser systems have achieved record output energies of 1mJ [2]. However, these high-energy systems have not been scaled beyond a few watts of average output power. Fiber laser systems are attractive for many applications because they offer the promise of high efficiency, compact, robust systems that are turn key. Applications such as cutting, drilling and materials processing, front end systems for high energy pulsed lasers (such as petawatts) and laser based sources of high spatial coherence, high flux x-rays all require high energy short pulses and two of the three of these applications also require high average power. The challenge in creating a high energy chirped pulse fiber laser system is to find a way to scale the output energy while avoiding nonlinear effects and maintaining good beam quality in the amplifier fiber. To this end, our 3-year LDRD program sought to demonstrate a high energy, high average power fiber laser system. This work included exploring designs of large mode area optical fiber amplifiers for high energy systems as well as understanding the issues associated chirped pulse amplification in optical fiber amplifier systems.

  11. Dual Sync Pulse orbital welding of Zeron 100

    SciTech Connect (OSTI)

    Warburton, G.R.; Spence, M.A. [Weir Materials Ltd., Manchester (United Kingdom); Potter, S.R. [Dimetrics, Inc., Davidson, NC (United States)

    1994-12-31T23:59:59.000Z

    The paper describes a new orbital GTAW welding system. Dual Synchronized Pulsation is a further development of the Sync Pulse mode of operation. In Sync Pulse operation the primary weld parameters (current, voltage and wire feed speed) are pulsed between a primary and background value together with synchronization to the torch oscillation position allied with presetting duration using in dwell, excursion and out dwell times. Dual Sync Pulse utilizes two wire feed systems feeding a chill wire directly into the rear of the weld pool on the side opposite the weld torch and the main wire feed. The chill wires fed into the trailing side of the torch absorbs energy from the weld pool effectively limiting heat transmitted to the base material. This technique provides higher deposition rates, decreased welding times and lower heat inputs per pound of deposited metal. Using Dual Sync Pulse, substantial increases in metal deposition rate compared to single wire technique were obtained together with lower heat inputs per kg (pound) of deposited metal. Both mechanical properties and corrosion test results met normal fabrication specification requirements. No evidence of intermetallic phase precipitation was found using optical microscopy. The ability to increase deposition rate without concurrent increase in heat input offers the fabricator significant advantages when welding a super duplex stainless steels such as Zeron 100. In addition, the reduced number of runs and lower heat inputs provide welds with less hoop shrinkage and lower residual stress.

  12. Two stroke homogenous charge compression ignition engine with pulsed air supplier

    DOE Patents [OSTI]

    Clarke, John M. (Chillicothe, IL)

    2003-08-05T23:59:59.000Z

    A two stroke homogenous charge compression ignition engine includes a volume pulsed air supplier, such as a piston driven pump, for efficient scavenging. The usage of a homogenous charge tends to decrease emissions. The use of a volume pulsed air supplier in conjunction with conventional poppet type intake and exhaust valves results in a relatively efficient scavenging mode for the engine. The engine preferably includes features that permit valving event timing, air pulse event timing and injection event timing to be varied relative to engine crankshaft angle. The principle use of the invention lies in improving diesel engines.

  13. SLIM, Short-pulse Technology for High Gradient Induction Accelerators

    SciTech Connect (OSTI)

    Arntz, Floyd; /Diversified Tech., Bedford; Kardo-Sysoev, A.; /Ioffe Phys. Tech. Inst.; Krasnykh, A.; /SLAC

    2008-12-16T23:59:59.000Z

    A novel short-pulse concept (SLIM) suited to a new generation of a high gradient induction particle accelerators is described herein. It applies advanced solid state semiconductor technology and modern microfabrication techniques to a coreless induction method of charged particle acceleration first proven on a macro scale in the 1960's. Because this approach avoids use of magnetic materials there is the prospect of such an accelerator working efficiently with accelerating pulses in the nanosecond range and, potentially, at megahertz pulse rates. The principal accelerator section is envisioned as a stack of coreless induction cells, the only active element within each being a single, extremely fast (subnanosecond) solid state opening switch: a Drift Step Recovery Diode (DSRD). Each coreless induction cell incorporates an electromagnetic pulse compressor in which inductive energy developed within a transmission-line feed structure over a period of tens of nanoseconds is diverted to the acceleration of the passing charge packet for a few nanoseconds by the abrupt opening of the DSRD switch. The duration of this accelerating output pulse--typically two-to-four nanoseconds--is precisely determined by a microfabricated pulse forming line connected to the cell. Because the accelerating pulse is only nanoseconds in duration, longitudinal accelerating gradients approaching 100 MeV per meter are believed to be achievable without inciting breakdown. Further benefits of this approach are that, (1) only a low voltage power supply is required to produce the high accelerating gradient, and, (2) since the DSRD switch is normally closed, voltage stress is limited to a few nanoseconds per period, hence the susceptibility to hostile environment conditions such as ionizing radiation, mismatch (e.g. in medical applications the peak beam current may be low), strong electromagnetic noise levels, etc is expected to be minimal. Finally, we observe the SLIM concept is not limited to linac applications; for instance, it could be employed to both accelerate the beam and to stabilize the superbunch mode of operation in circular track machines.

  14. Fiber Optic Picosecond Laser Pulse Transmission Line for Hydrogen Ion Beam Profile Measurement

    SciTech Connect (OSTI)

    Liu, Yun [ORNL; Huang, Chunning [ORNL; Aleksandrov, Alexander V [ORNL

    2013-01-01T23:59:59.000Z

    We present a fiber optic laser pulse transmission line for non-intrusive longitudinal profile measurement of the hydrogen ion (H-) beam at the front-end of the Spallation Neutron Source (SNS) accelerator. The 80.5 MHz, 2.5 ps, multi-killowatt optical pulses are delivered to the accelerator beam line through a large mode area polarization maintaining optical fiber to ensure a high measurement stability. The transmission efficiency, output laser beam quality, pulse jitter and pulse width broadening over a 100-ft fiber line are experimentally investigated. A successful measurement of the H- beam microbunch (~130 ps) profile is obtained. Our experiment is the first demonstration of particle beam profile diagnostics using fiber optic laser pulse transmission line.

  15. Capacitor discharge pulse analysis.

    SciTech Connect (OSTI)

    Baker, Michael Sean; Griffiths, Stewart K.; Tanner, Danelle Mary

    2013-08-01T23:59:59.000Z

    Capacitors used in firing sets and other high discharge current applications are discharge tested to verify performance of the capacitor against the application requirements. Parameters such as capacitance, inductance, rise time, pulse width, peak current and current reversal must be verified to ensure that the capacitor will meet the application needs. This report summarizes an analysis performed on the discharge current data to extract these parameters by fitting a second-order system model to the discharge data and using this fit to determine the resulting performance metrics. Details of the theory and implementation are presented. Using the best-fit second-order system model to extract these metrics results in less sensitivity to noise in the measured data and allows for direct extraction of the total series resistance, inductance, and capacitance.

  16. Pulsed ion beam source

    DOE Patents [OSTI]

    Greenly, John B. (Lansing, NY)

    1997-01-01T23:59:59.000Z

    An improved pulsed ion beam source having a new biasing circuit for the fast magnetic field. This circuit provides for an initial negative bias for the field created by the fast coils in the ion beam source which pre-ionize the gas in the source, ionize the gas and deliver the gas to the proper position in the accelerating gap between the anode and cathode assemblies in the ion beam source. The initial negative bias improves the interaction between the location of the nulls in the composite magnetic field in the ion beam source and the position of the gas for pre-ionization and ionization into the plasma as well as final positioning of the plasma in the accelerating gap. Improvements to the construction of the flux excluders in the anode assembly are also accomplished by fabricating them as layered structures with a high melting point, low conductivity material on the outsides with a high conductivity material in the center.

  17. Switching power pulse system

    DOE Patents [OSTI]

    Aaland, Kristian (Livermore, CA)

    1983-01-01T23:59:59.000Z

    A switching system for delivering pulses of power from a source (10) to a load (20) using a storage capacitor (C3) charged through a rectifier (D1, D2), and maintained charged to a reference voltage level by a transistor switch (Q1) and voltage comparator (12). A thyristor (22) is triggered to discharge the storage capacitor through a saturable reactor (18) and fractional turn saturable transformer (16) having a secondary to primary turn ratio N of n:l/n=n.sup.2. The saturable reactor (18) functions as a "soaker" while the thyristor reaches saturation, and then switches to a low impedance state. The saturable transformer functions as a switching transformer with high impedance while a load coupling capacitor (C4) charges, and then switches to a low impedance state to dump the charge of the storage capacitor (C3) into the load through the coupling capacitor (C4). The transformer is comprised of a multilayer core (26) having two secondary windings (28, 30) tightly wound and connected in parallel to add their output voltage and reduce output inductance, and a number of single turn windings connected in parallel at nodes (32, 34) for the primary winding, each single turn winding linking a different one of the layers of the multilayer core. The load may be comprised of a resistive beampipe (40) for a linear particle accelerator and capacitance of a pulse forming network (42). To hold off discharge of the capacitance until it is fully charged, a saturable core (44) is provided around the resistive beampipe (40) to isolate the beampipe from the capacitance (42) until it is fully charged.

  18. Means and method for characterizing high power, ultra short laser pulses in a real time, on line manner

    DOE Patents [OSTI]

    Veligdan, James T. (Manorville, NY)

    1994-01-01T23:59:59.000Z

    An ultra short (<10 ps), high power laser pulse is temporally characterized by a system that uses a physical measurement of a wavefront that has been altered in a known manner. The system includes a first reflection switch to remove a portion of a pulse from a beam of pulses, then includes a second reflection switch, operating in a mode that is opposite to the first reflection switch, to slice off a portion of that removed portion. The sliced portion is then directed to a measuring device for physical measurement. The two reflection switches are arranged with respect to each other and with respect to the beam of ultra short pulses such that physical measurement of the sliced portion is related to the temporal measurement of the ultra short pulse by a geometric or trigonometric relationship. The reflection switches are operated by a control pulse that is directed to impinge on each of the reflection switches at a 90.degree. angle of incidence.

  19. Resonance Excitation of Longitudinal High Order Modes in Project X Linac

    SciTech Connect (OSTI)

    Khabiboulline, T.N.; Sukhanov, A.AUTHOR = Awida, M.; Gonin, I.; Lunin, A.AUTHOR = Solyak, N.; Yakovlev, V.; /Fermilab

    2012-05-01T23:59:59.000Z

    Results of simulation of power loss due to excitation of longitudinal high order modes (HOMs) in the accelerating superconducting RF system of CW linac of Project X are presented. Beam structures corresponding to the various modes of Project X operation are considered: CW regime for 3 GeV physics program; pulsed mode for neutrino experiments; and pulsed regime, when Project X linac operates as a driver for Neutrino Factory/Muon Collider. Power loss and associated heat load due to resonance excitation of longitudinal HOMs are shown to be small in all modes of operation. Conclusion is made that HOM couplers can be removed from the design of superconducting RF cavities of Project X linac.

  20. Pulsed atmospheric fluidized bed combustion. Final report

    SciTech Connect (OSTI)

    Not Available

    1989-11-01T23:59:59.000Z

    In order to verify the technical feasibility of the MTCI Pulsed Atmospheric Fluidized Bed Combustor technology, a laboratory-scale system was designed, built and tested. Important aspects of the operational and performance parameters of the system were established experimentally. A considerable amount of the effort was invested in the initial task of constructing an AFBC that would represent a reasonable baseline against which the performance of the PAFBC could be compared. A summary comparison of the performance and emissions data from the MTCI 2 ft {times} 2 ft facility (AFBC and PAFBC modes) with those from conventional BFBC (taller freeboard and recycle operation) and circulating fluidized bed combustion (CFBC) units is given in Table ES-1. The comparison is for typical high-volatile bituminous coals and sorbents of average reactivity. The values indicated for BFBC and CFBC were based on published information. The AFBC unit that was designed to act as a baseline for the comparison was indeed representative of the larger units even at the smaller scale for which it was designed. The PAFBC mode exhibited superior performance in relation to the AFBC mode. The higher combustion efficiency translates into reduced coal consumption and lower system operating cost; the improvement in sulfur capture implies less sorbent requirement and waste generation and in turn lower operating cost; lower NO{sub x} and CO emissions mean ease of site permitting; and greater steam-generation rate translates into less heat exchange surface area and reduced capital cost. Also, the PAFBC performance generally surpasses those of conventional BFBC, is comparable to CFBC in combustion and NO{sub x} emissions, and is better than CFBC in sulfur capture and CO emissions even at the scaled-down size used for the experimental feasibility tests.

  1. Design and testing of an internal mode converter for a 1.5 MW, 110 GHz gyrotron with a depressed collector

    E-Print Network [OSTI]

    Tax, David Samuel

    We report experimental results on a 1.5 MW, 110 GHz, 3 microsecond pulsed gyrotron with a single-stage depressed collector. A simplified mode converter with smooth mirror surfaces has been installed in the tube. The converter ...

  2. Hyper dispersion pulse compressor for chirped pulse amplification systems

    DOE Patents [OSTI]

    Barty, Christopher P. J. (Hayward, CA)

    2011-11-29T23:59:59.000Z

    A grating pulse compressor configuration is introduced for increasing the optical dispersion for a given footprint and to make practical the application for chirped pulse amplification (CPA) to quasi-narrow bandwidth materials, such as Nd:YAG. The grating configurations often use cascaded pairs of gratings to increase angular dispersion an order of magnitude or more. Increased angular dispersion allows for decreased grating separation and a smaller compressor footprint.

  3. Prefire identification for pulse power systems

    DOE Patents [OSTI]

    Longmire, Jerry L. (Los Alamos, NM); Thuot, Michael E. (Espanola, NM); Warren, David S. (Los Alamos, NM)

    1985-01-01T23:59:59.000Z

    Prefires in a high-power, high-frequency, multi-stage pulse generator are detected by a system having an EMI shielded pulse timing transmitter associated with and tailored to each stage of the pulse generator. Each pulse timing transmitter upon detection of a pulse triggers a laser diode to send an optical signal through a high frequency fiber optic cable to a pulse timing receiver which converts the optical signal to an electrical pulse. The electrical pulses from all pulse timing receivers are fed through an OR circuit to start a time interval measuring device and each electrical pulse is used to stop an individual channel in the measuring device thereby recording the firing sequence of the multi-stage pulse generator.

  4. Pulsed ion beam source

    DOE Patents [OSTI]

    Greenly, J.B.

    1997-08-12T23:59:59.000Z

    An improved pulsed ion beam source is disclosed having a new biasing circuit for the fast magnetic field. This circuit provides for an initial negative bias for the field created by the fast coils in the ion beam source which pre-ionize the gas in the source, ionize the gas and deliver the gas to the proper position in the accelerating gap between the anode and cathode assemblies in the ion beam source. The initial negative bias improves the interaction between the location of the nulls in the composite magnetic field in the ion beam source and the position of the gas for pre-ionization and ionization into the plasma as well as final positioning of the plasma in the accelerating gap. Improvements to the construction of the flux excluders in the anode assembly are also accomplished by fabricating them as layered structures with a high melting point, low conductivity material on the outsides with a high conductivity material in the center. 12 figs.

  5. Electrodeless short pulse laser

    SciTech Connect (OSTI)

    Proud, J.M.; Baird, D.H.; Kramer, J.M.; Lester, J.E.

    1986-06-03T23:59:59.000Z

    A system is described for the generation of coherent beams of radiation, which consists of: a tube defining a resonant cavity containing a discharge plasma capable of producing coherent radiation, the tube having an elongated shape along an optical axis along the longitudinal axis of the tube, the tube having end portions and an elongated constricted portion connecting the end portions, and the tube having laser windows sealing the end portions to form a closed envelope containing the discharge plasma, a mirror on the optical axis near at least one end of the tube, first and second external electrode means on the outside surfaces of the tube adjacent the opposite ends of the tube, the external electrode means being capacitively coupled to the discharge plasma, and means for providing a source of short pulses electrically to the first external electrode means and means for coupling the second external electrode means to a point of reference potential, further characterized by first and second internal electrode means respectively adjacent the first and second external electrode means and capacitively coupled thereto, the tube having end portions sealed to form a closed envelope containing the discharge plasma and the internal electrode means.

  6. Method and apparatus for improved efficiency in a pulse-width-modulated alternating current motor drive

    DOE Patents [OSTI]

    Konrad, C.E.; Boothe, R.W.

    1996-01-23T23:59:59.000Z

    A scheme for optimizing the efficiency of an AC motor drive operated in a pulse-width-modulated mode provides that the modulation frequency of the power furnished to the motor is a function of commanded motor torque and is higher at lower torque requirements than at higher torque requirements. 6 figs.

  7. Method and apparatus for improved efficiency in a pulse-width-modulated alternating current motor drive

    DOE Patents [OSTI]

    Konrad, C.E.; Boothe, R.W.

    1994-02-15T23:59:59.000Z

    A scheme for optimizing the efficiency of an AC motor drive operated in a pulse-width-modulated mode provides that the modulation frequency of the power furnished to the motor is a function of commanded motor torque and is higher at lower torque requirements than at higher torque requirements. 6 figures.

  8. Monolithically Integrated Selectable Repetition-Rate Laser Diode Source of Picosecond Optical Pulses

    E-Print Network [OSTI]

    Guo, Xuhan; Olle, Vojtech; Quarterman, Adrian; Wonfor, Adrian; Penty, Richard; White, Ian

    2014-06-15T23:59:59.000Z

    with a record high peak power of 2.5 kW, repetition rate of 330 MHz from a distributed passively mode locked MOPA device followed by an optical isolator, a tapered amplifier and a linear pulse compressor. Ding et al. [12] have reported picosecond...

  9. Method and apparatus for improved efficiency in a pulse-width-modulated alternating current motor drive

    DOE Patents [OSTI]

    Konrad, Charles E. (Roanoke, VA); Boothe, Richard W. (Roanoke, VA)

    1994-01-01T23:59:59.000Z

    A scheme for optimizing the efficiency of an AC motor drive operated in a pulse-width-modulated mode provides that the modulation frequency of the power furnished to the motor is a function of commanded motor torque and is higher at lower torque requirements than at higher torque requirements.

  10. Method and apparatus for improved efficiency in a pulse-width-modulated alternating current motor drive

    DOE Patents [OSTI]

    Konrad, Charles E. (Roanoke, VA); Boothe, Richard W. (Roanoke, VA)

    1996-01-01T23:59:59.000Z

    A scheme for optimizing the efficiency of an AC motor drive operated in a pulse-width-modulated mode provides that the modulation frequency of the power furnished to the motor is a function of commanded motor torque and is higher at lower torque requirements than at higher torque requirements.

  11. Excitation of the Morse oscillator by an ultrashort chirped pulse

    SciTech Connect (OSTI)

    Astapenko, V. A., E-mail: astval@mail.ru; Romadanovskii, M. S. [Moscow Institute of Physics and Technology (Russian Federation)

    2010-03-15T23:59:59.000Z

    The excitation of the classic Morse oscillator by an ultrashort electromagnetic pulse with a linear frequency chirp is studied theoretically. Formulas are derived for the oscillation amplitude and the radiation power averaged over a period as functions of the excitation energy for free oscillations of the Morse oscillator. Analytical expressions for describing the oscillator motion after the end of the pulse are obtained in the harmonic limit. In the general case of arbitrary parameters of the problem, the specific features of an excited Morse oscillator are analyzed numerically. Prominence is given to the effect of chirp on the excitation energy. The consideration is performed in terms of dimensionless variables, which makes it possible to apply the results obtained to a wide range of molecular systems and exciting-pulse parameters.

  12. Ultrasonic flowmetering with reflected pulses

    E-Print Network [OSTI]

    Hoyle, David C.

    1984-01-01T23:59:59.000Z

    A transit time type ultrasonic flowmeter was tested with two different reflected pulse trajectories in flowing air at ambient conditions against an orifice meter. The flowmeter was designed to be highly accurate, to require ...

  13. Vacuum electron acceleration by using two variable frequency laser pulses

    SciTech Connect (OSTI)

    Saberi, H.; Maraghechi, B. [Department of Physics, Amirkabir University of Technology, 15875-4413 Tehran (Iran, Islamic Republic of)] [Department of Physics, Amirkabir University of Technology, 15875-4413 Tehran (Iran, Islamic Republic of)

    2013-12-15T23:59:59.000Z

    A method is proposed for producing a relativistic electron bunch in vacuum via direct acceleration by using two frequency-chirped laser pulses. We consider the linearly polarized frequency-chiped Hermit-Gaussian 0, 0 mode lasers with linear chirp in which the local frequency varies linearly in time and space. Electron motion is investigated through a numerical simulation using a three-dimensional particle trajectory code in which the relativistic Newton's equations of motion with corresponding Lorentz force are solved. Two oblique laser pulses with proper chirp parameters and propagation angles are used for the electron acceleration along the z-axis. In this way, an electron initially at rest located at the origin could achieve high energy, ?=319 with the scattering angle of 1.02{sup ?} with respect to the z-axis. Moreover, the acceleration of an electron in different initial positions on each coordinate axis is investigated. It was found that this mechanism has the capability of producing high energy electron microbunches with low scattering angles. The energy gain of an electron initially located at some regions on each axis could be greatly enhanced compared to the single pulse acceleration. Furthermore, the scattering angle will be lowered compared to the acceleration by using laser pulses propagating along the z-axis.

  14. Fluid modes of a spherically confined Yukawa plasma

    SciTech Connect (OSTI)

    Kaehlert, H.; Bonitz, M. [Institut fuer Theoretische Physik und Astrophysik, Christian-Albrechts Universitaet zu Kiel, 24098 Kiel (Germany)

    2010-09-15T23:59:59.000Z

    The normal modes of a three-dimensional Yukawa plasma in an isotropic harmonic confinement are investigated by solving the linearized cold fluid equations. The eigenmodes are found analytically and expressed in terms of hypergeometric functions. It is found that the mode frequencies solely depend on the dimensionless plasma parameter {xi}={kappa}R, where R is the plasma radius and {kappa} is the inverse screening length. The eigenfrequencies increase monotonically with {xi} and saturate in the limit {xi}{yields}{infinity}. Compared with the results in the Coulomb limit [D. H. E. Dubin, Phys. Rev. Lett. 66, 2076 (1991)], we find an additional class of modes characterized by the number n which determines the number of radial nodes in the perturbed potential. These modes originate from the degenerate bulk modes of the Coulomb system. Analytical formulas for the eigenfrequencies are derived for limiting cases.

  15. Short pulse free electron laser amplifier

    DOE Patents [OSTI]

    Schlitt, Leland G. (Livermore, CA); Szoke, Abraham (Fremont, CA)

    1985-01-01T23:59:59.000Z

    Method and apparatus for amplification of a laser pulse in a free electron laser amplifier where the laser pulse duration may be a small fraction of the electron beam pulse duration used for amplification. An electron beam pulse is passed through a first wiggler magnet and a short laser pulse to be amplified is passed through the same wiggler so that only the energy of the last fraction, f, (f<1) of the electron beam pulse is consumed in amplifying the laser pulse. After suitable delay of the electron beam, the process is repeated in a second wiggler magnet, a third, . . . , where substantially the same fraction f of the remainder of the electron beam pulse is consumed in amplification of the given short laser pulse in each wiggler magnet region until the useful electron beam energy is substantially completely consumed by amplification of the laser pulse.

  16. Composition dependence of the in-plane Cu-O bond-stretching LO phonon mode in YBa2Cu3O6+x

    SciTech Connect (OSTI)

    Stercil, F. [University of Pennsylvania; Egami, T. [University of Pennsylvania; Mook Jr, Herbert A [ORNL; Yethiraj, Mohana [ORNL; Chung, J.-H. [National Institute of Standards and Technology (NIST); Arai, M. [Institute of Materials Structure Science, Japan; Frost, C. [ISIS Facility, Rutherford Appleton Laboratory; Dogan, F. [University of Washington, Seattle

    2008-01-01T23:59:59.000Z

    An inelastic pulsed neutron scattering study was performed on the dependence of the dispersion and spectral intensity of the in-plane Cu-O bond-stretching LO phonon mode on doped charge density. The measurements were made in the time-of-flight mode with the multiangle position sensitive spectrometer of the ISIS facility on single crystals of YBa{sub 2}Cu{sub 3}O{sub 6+x} (x=0.15, 0.35, 0.6, 0.7, and 0.95). The focus of the study is the in-plane Cu-O bond-stretching LO phonon mode, which is known for strong electron-phonon coupling and unusual dependence on composition and temperature. It is shown that the dispersions for the samples with x=0.35, 0.6, and 0.7 are similar to the superposition of those for x=0.15 and 0.95 samples, and cannot be explained in terms of the structural anisotropy. It is suggested that the results are consistent with the model of nanoscale electronic phase separation, with the fraction of the phases being dependent on the doped charge density.

  17. Analytical modeling of pulse-pileup distortion using the true pulse shape; applications to Fermi-GBM

    E-Print Network [OSTI]

    Vandiver Chaplin; Narayana Bhat; Michael Briggs; Valerie Connaughton

    2013-04-29T23:59:59.000Z

    Pulse-pileup affects most photon counting systems and occurs when photon detections occur faster than the detector's registration and recovery time. At high input rates, shaped pulses interfere and the source spectrum, as well as intensity information, get distorted. For instruments using bipolar pulse shaping there are two aspects to consider: `peak' and `tail' pileup effects, which raise and lower the measured energy, respectively. Peak effects have been extensively modeled in the past. Tail effects have garnered less attention due to the increased complexity: bipolar tails mean the tail pulse-height measurement depends on events in more than one time interval. We leverage previous work to derive an accurate, semi-analytical prediction for peak and tail pileup, up to high orders. We use the true pulse shape from the detectors of the Fermi Gamma-ray Burst Monitor. The measured spectrum is calculated by writing exposure time as a state-space expansion of overlapping pileup states and is valid up to very high rates. This expansion models losses due to fixed and extendable deadtime by averaging overlap configurations. Additionally, the model correctly predicts energy-dependent losses due to tail subtraction (sub-threshold) effects. We discuss pileup losses in terms of the true rate of photon detections versus the recorded count rate.

  18. Calculation of the stochastic pulsed Rossi-alpha formula and its experimental verification

    E-Print Network [OSTI]

    Pázsit, Imre

    Calculation of the stochastic pulsed Rossi-alpha formula and its experimental verification Y, Tokai-mura, Naka-gun, Ibaraki 319-1195, Japan Abstract The Rossi-alpha formula for subcritical systems that the present formula consists of the correlated and uncorrelated terms and an oscillating term whose period

  19. 714 IEEE PHOTONICS TECHNOLOGY LETTERS, VOL. 12, NO. 6, JUNE 2000 Skew and Jitter Removal Using Short Optical Pulses

    E-Print Network [OSTI]

    Miller, David A. B.

    , and retransmission of digital data. Index Terms--CMOS integrated circuits, optical intercon- nections, optical pulses, system design, and timing issues. Here, we define short pulse optical interconnects as those using-98-1-0002, and a subaward from the University of New Mexico. The authors are with the Departments of Applied Physics

  20. 108 GHz passive mode locking of a multiple quantum well semiconductor laser with an intracavity absorber

    SciTech Connect (OSTI)

    Sanders, S.; Eng, L.; Paslaski, J.; Yariv, A. (Department of Applied Physics 128-95, California Institute of Technology, Pasadena, California 91125 (US))

    1990-01-22T23:59:59.000Z

    A two-section multiple quantum well laser is passively mode locked without an external cavity at {similar to}108 GHz. The pulse widths average 2.4 ps and have a time-bandwidth product of 1.1. Self-pulsations at frequencies up to 8 GHz are also observed.

  1. Mode-locking of monolithic laser diodes incorporating coupled-resonator optical

    E-Print Network [OSTI]

    Fan, Shanhui

    57, 12,127­12,133 (1998). 6. A. Yariv, Y. Xu, R. K. Lee, and A. Scherer, "Coupled-resonator optical and A. Yariv, "Optical pulse propagation in the tight-binding approximation," Opt. Express 9, 91: (050.0050) Diffraction and gratings; (140.4050) Mode-locked lasers. References and links 1. G. A

  2. Mode-Locking in 25-km Fibre Laser , S.Turitsyn

    E-Print Network [OSTI]

    Kobtsev, Sergei M.

    generation of ultra-short optical pulses with high energy. The extension of the cavity lengthMode-Locking in 25-km Fibre Laser A.Ivanenko (1,2) , S.Turitsyn (1) , S.Kobsev (2) , M.Dubov (1) (1) Photonics Research Group, Aston University, UK, s.k.turitsyn@aston.ac.uk (2) Laser Systems Laboratory

  3. Helium Refrigerator Design for Pulsed Heat Load in Tokamaks

    SciTech Connect (OSTI)

    Kuendig, A.; Schoenfeld, H. [Linde Kryotechnik AG, Dattlikonerstrasse 5, CH-8422 Pfungen (Switzerland)

    2006-04-27T23:59:59.000Z

    Nuclear fusion reactors of the Tokamak type will be operated in a pulsed mode requiring the helium refrigerator to remove periodically large heat loads in time steps of approximately one hour. What are the necessary steps for a refrigerator to cope with such load variations?A series of numerical simulations has been performed indicating the possibility of an active refrigerator control with low exergetic losses. A basic comparison is made between the largest existing refrigerator sizes and the size required to service for example the ITER requirements.

  4. Passive mode locking of buried heterostructure lasers with nonuniform current injection

    SciTech Connect (OSTI)

    Harder, C.; Smith, J.S.; Lau, K.Y.; Yariv, A.

    1983-05-01T23:59:59.000Z

    In this letter we report on a novel method to passively mode lock a semiconductor laser. We present experimental results of GaAlAs buried heterostructure semiconductor laser with a split contact coupled to an external cavity. The split contact structure is used to introduce a controllable amount of saturable absorption which is necessary to initiate passive mode locking. Unlike previous passive mode locking techniques, the method presented does not rely on absorption introduced by damaging the crystal and is consequently inherently more reliable. We have obtained pulses with a full width at half-maximum of 35 ps at repetition frequencies between 500 MHz and 1.5 GHz.

  5. A wide bandwidth free-electron laser with mode locking using current modulation.

    SciTech Connect (OSTI)

    Kur, E.; Dunning, D. J.; McNeil, B. W. J.; Wurtele, J.; Zholents, A. A. (Accelerator Systems Division (APS)); (Univ. of California at Berkeley); (Univ. of Strathclyde); (STFC Daresbury Lab.); (LBNL)

    2011-01-20T23:59:59.000Z

    A new scheme for mode locking a free-electron laser amplifier is proposed based on electron beam current modulation. It is found that certain properties of the original concept, based on the energy modulation of electrons, are improved including the spectral brightness of the source and the purity of the series of short pulses. Numerical comparisons are made between the new and old schemes and between a mode-locked free-electron laser and self-amplified spontaneous emission free-electron laser. Illustrative examples using a hypothetical mode-locked free-electron laser amplifier are provided. The ability to generate intense coherent radiation with a large bandwidth is demonstrated.

  6. Plasma dynamics in a discharge produced by a pulsed dual frequency inductively coupled plasma source

    SciTech Connect (OSTI)

    Mishra, Anurag; Lee, Sehan [Department of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon, Gyeonggi-do 440-746 (Korea, Republic of); Yeom, Geun Y., E-mail: gyyeom@skku.edu [Department of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon, Gyeonggi-do 440-746, South Korea and SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon, Gyeonggi-do 440-746 (Korea, Republic of)

    2014-11-01T23:59:59.000Z

    Using a Langmuir probe, time resolved measurements of plasma parameters were carried out in a discharge produced by a pulsed dual frequency inductively coupled plasma source. The discharge was sustained in an argon gas environment at a pressure of 10 mTorr. The low frequency (P{sub 2} {sub MHz}) was pulsed at 1 kHz and a duty ratio of 50%, while high frequency (P{sub 13.56} {sub MHz}) was maintained in the CW mode. All measurements were carried out at the center of the discharge and 20?mm above the substrate. The results show that, at a particular condition (P{sub 2} {sub MHz}?=?200 W and P{sub 13.56} {sub MHz?}=?600 W), plasma density increases with time and stabilizes at up to ?200 ?s after the initiation of P{sub 2} {sub MHz} pulse at a plasma density of (2?×?10{sup 17} m{sup ?3}) for the remaining duration of pulse “on.” This stabilization time for plasma density increases with increasing P{sub 2} {sub MHz} and becomes ?300 ?s when P{sub 2} {sub MHz} is 600 W; however, the growth rate of plasma density is almost independent of P{sub 2} {sub MHz}. Interestingly, the plasma density sharply increases as the pulse is switched off and reaches a peak value in ?10 ?s, then decreases for the remaining pulse “off-time.” This phenomenon is thought to be due to the sheath modulation during the transition from “pulse on” to “pulse off” and partly due to RF noise during the transition period. The magnitude of peak plasma density in off time increases with increasing P{sub 2} {sub MHz}. The plasma potential and electron temperature decrease as the pulse develops and shows similar behavior to that of the plasma density when the pulse is switched off.

  7. Ionization by few-cycle pulses: Tracing the electron orbits

    SciTech Connect (OSTI)

    Milosevic, D.B. [Faculty of Science, University of Sarajevo, Zmaja od Bosne 35, 71000 Sarajevo (Bosnia and Herzegowina); Paulus, G.G. [Department of Physics, Texas A and M University, College Station, Texas 77843-4242 (United States); Becker, W. [Max-Born-Institut, Max-Born-Strasse 2a, 12489 Berlin (Germany)

    2005-06-15T23:59:59.000Z

    High-order above-threshold ionization by few-cycle laser pulses is analyzed in terms of quantum orbits. For a given carrier-envelope phase, the number of contributing orbits and their ionization and rescattering times determine the shape of the angle-resolved spectrum in all detail. Conversely, analysis of a given spectrum reveals the carrier-envelope phase and the various interfering pathways from which the electron could choose.

  8. Obtaining two attosecond pulses pulses for x-ray stimulated Raman spectroscopy

    E-Print Network [OSTI]

    Zholents, Alexander

    2010-01-01T23:59:59.000Z

    delay between two ultra-short laser pulses obtained from theto the timing of the ultra-short laser pulse and can easilybunch interacting with ultra-short laser pulses. Here, we

  9. Optical pulse dynamics for quantum-dot logic operations in a photonic-crystal waveguide

    SciTech Connect (OSTI)

    Ma, Xun; John, Sajeev [Department of Physics, University of Toronto, Toronto, Ontario, M5S 1A7 Canada (Canada)

    2011-11-15T23:59:59.000Z

    We numerically demonstrate all-optical logic operations with quantum dots (QDs) embedded in a bimodal photonic-crystal waveguide using Maxwell-Bloch equations in a slowly varying envelope approximation (SVEA). The two-level QD excitation level is controlled by one or more femtojoule optical driving pulses passing through the waveguide. Specific logic operations depend on the relative pulse strengths and their detunings from an inhomogeneouslly broadened (about 1% for QD transitions centered at 1.5 {mu}m) QD transition. This excitation controlled two-level medium then determines passage of subsequent probe optical pulses. Envelope equations for electromagnetic waves in the linear dispersion and cutoff waveguide modes are derived to simplify solution of the coupled Maxwell-Bloch equations in the waveguide. These determine the quantum mechanical evolution of the QD excitation and its polarization, driven by classical electromagnetic (EM) pulses near a sharp discontinuity in the EM density of states of the bimodal waveguide. Different configurations of the driving pulses lead to distinctive relations between driving pulse strength and probe pulse passage, representing all-optical logic and, or, and not operations. Simulation results demonstrate that such operations can be done on picosecond time scales and within a waveguide length of about 10 {mu}m in a photonic-band-gap (PBG) optical microchip.

  10. Simulation of Double-Pulse Laser Ablation

    SciTech Connect (OSTI)

    Povarnitsyn, Mikhail E.; Khishchenko, Konstantin V.; Levashov, Pavel R. [Joint Institute for High Temperatures of RAS, Izhorskaya 13 Bldg 2, Moscow, 125412 (Russian Federation); Itina, Tatian E. [Laboratoire Hubert Curien, UMR CNRS 5516, 18 rue Benoit Lauras, Bat. F, 42000, St-Etienne (France)

    2010-10-08T23:59:59.000Z

    We investigate the physical reasons of a strange decrease in the ablation depth observed in femtosecond double-pulse experiments with increasing delay between the pulses. Two ultrashort pulses of the same energy produce the crater which is less than that created by a single pulse. Hydrodynamic simulation shows that the ablation mechanism is suppressed when the delay between the pulses exceeds the electron-ion relaxation time. In this case, the interaction of the second laser pulse with the expanding target material leads to the formation of the second shock wave suppressing the rarefaction wave created by the first pulse. The modeling of the double-pulse ablation for different delays between pulses confirms this explanation.

  11. Solution Processed MoS2-PVA Composite for Sub-Bandgap Mode-Locking of a Wideband Tunable Ultrafast Er:Fiber Laser

    E-Print Network [OSTI]

    Zhang, Meng; Howe, Richard C. T.; Woodward, Robert I.; Kelleher, Edmund J. R.; Torrisi, Felice; Hu, Guohua; Popov, Sergei V.; Taylor, J. Roy; Hasan, Tawfique

    2014-11-11T23:59:59.000Z

    with stable, picosecond pulses, tunable from 1535 nm to 1565 nm 2 Solution Processed MoS2-PVA Composite for Sub-Bandgap Mode-Locking of a Wideband Tunable Ultrafast Er:Fiber Laser Meng Zhang1, Richard C. T. Howe2, Robert I. Woodward1... ! to! relaxation! of! thermalized! electron! and!phonon! distribution! [3].! This! combination! of!properties!makes!MoS2!a!suitable!saturable!absorber!(SA)! for! ultrafast! mode+locked! pulsed! lasers,! with!the! potential! for! pulse! generation! at...

  12. Control of high power pulse extracted from the maximally compressed pulse in a nonlinear optical fiber

    E-Print Network [OSTI]

    Yang, Guangye; Jia, Suotang; Mihalache, Dumitru

    2013-01-01T23:59:59.000Z

    We address the possibility to control high power pulses extracted from the maximally compressed pulse in a nonlinear optical fiber by adjusting the initial excitation parameters. The numerical results show that the power, location and splitting order number of the maximally compressed pulse and the transmission features of high power pulses extracted from the maximally compressed pulse can be manipulated through adjusting the modulation amplitude, width, and phase of the initial Gaussian-type perturbation pulse on a continuous wave background.

  13. Pulse combustor with controllable oscillations

    DOE Patents [OSTI]

    Richards, George A. (Morgantown, WV); Welter, Michael J. (Columbiana, OH); Morris, Gary J. (Morgantown, WV)

    1992-01-01T23:59:59.000Z

    A pulse combustor having thermally induced pulse combustion in a continuously flowing system is described. The pulse combustor is fitted with at lease one elongated ceramic body which significantly increases the heat transfer area in the combustion chamber of the combustor. The ceramic body or bodies possess sufficient mass and heat capacity to ignite the fuel-air charge once the ceramic body or bodies are heated by conventional spark plug initiated combustion so as to provide repetitive ignition and combustion of sequentially introduced fuel-air charges without the assistance of the spark plug and the rapid quenching of the flame after each ignition in a controlled manner so as to provide a selective control over the oscillation frequency and amplitude. Additional control over the heat transfer in the combustion chamber is provided by employing heat exchange mechanisms for selectively heating or cooling the elongated ceramic body or bodies and/or the walls of the combustion chamber.

  14. Radial flow pulse jet mixer

    DOE Patents [OSTI]

    VanOsdol, John G.

    2013-06-25T23:59:59.000Z

    The disclosure provides a pulse jet mixing vessel for mixing a plurality of solid particles. The pulse jet mixing vessel is comprised of a sludge basin, a flow surface surrounding the sludge basin, and a downcoming flow annulus between the flow surface and an inner shroud. The pulse jet mixing vessel is additionally comprised of an upper vessel pressurization volume in fluid communication with the downcoming flow annulus, and an inner shroud surge volume separated from the downcoming flow annulus by the inner shroud. When the solid particles are resting on the sludge basin and a fluid such as water is atop the particles and extending into the downcoming flow annulus and the inner shroud surge volume, mixing occurs by pressurization of the upper vessel pressurization volume, generating an inward radial flow over the flow surface and an upwash jet at the center of the sludge basin.

  15. Radio frequency-power and the ring-mode to red-mode transition in an inductively coupled plasma

    SciTech Connect (OSTI)

    Coffer, J. G.; Camparo, J. C. [Physical Sciences Laboratories, The Aerospace Corporation, P.O. Box 92957, Los Angeles, California 90009 (United States)

    2012-04-15T23:59:59.000Z

    The optical output of an alkali-metal inductively coupled plasma (alkali-ICP) plays an important role in both atomic magnetometers and atomic clocks, producing these devices' atomic signals through optical pumping. Unfortunately, though the alkali-ICP's optical pumping efficiency grows exponentially with temperature, at relatively high temperatures ({approx}140 deg. C) the discharge transitions from ''ring mode'' to ''red mode'', which is a spectral change in the plasma's output that corresponds broadly to a transition from ''good emission'' for optical pumping to ''poor emission.'' Recently, evidence has accumulated pointing to radiation trapping as the mechanism driving the ring-mode to red-mode transition, suggesting that the phenomenon is primarily linked to the alkali vapor's temperature. However, observations of the transition made in the 1960 s, demonstrating that the ICP temperature associated with the transition depended on rf-power, would appear to cast doubt on this mechanism. Here, we carefully investigate the influence of rf-power on the ring-mode to red-mode transition, finding that rf-power only affects the transition through discharge heating. Thus, the present work shows that the primary effect of rf-power on the ring-mode to red-mode transition can be understood in terms of the radiation trapping mechanism.

  16. Edge-Localized-Mode Suppression through Density-Profile Modification with Lithium-Wall Coatings in the National Spherical Torus Experiment

    E-Print Network [OSTI]

    Princeton Plasma Physics Laboratory

    a pulsed power load that would limit the lifetime of plasma-facing components (PFCs) unless the energyEdge-Localized-Mode Suppression through Density-Profile Modification with Lithium-Wall Coatings to low-n peeling or ballooning modes, while broader pressure profiles stabilized the post-Li discharges

  17. Plasmon mode excitation and photoluminescence enhancement on silver nanoring

    E-Print Network [OSTI]

    Kuchmizhak, A A; Kulchin, Yu N; Vitrik, O B

    2015-01-01T23:59:59.000Z

    We demonstrate a simple and high-performance laser-assisted technique for silver nanoring fabrication, which includes the ablation of the Ag film by focused nanosecond pulses and subsequent reactive ion polishing. The nanoring diameter and thickness can be controlled by optimizing both the pulse energy and the metal film thickness at laser ablation step, while the subsequent reactive ion polishing provides the ability to fabricate the nanoring with desirable height. Scattering patterns of s-polarized collimated laser beam obliquely illuminating the nanoring demonstrate the focal spot inside the nanoring shifted from its center at a distance of ~ 0.57Rring. Five-fold enhancement of the photoluminescence signal from the Rhodamine 6G organic dye near the Ag nanoring was demonstrated. This enhancement was attributed to the increase of the electromagnetic field amplitude near the nanoring surface arising from excitation of the multipole plasmon modes traveling along the nanoring. This assumption was confirmed by d...

  18. Electron geodesic acoustic modes in electron temperature gradient mode turbulence

    SciTech Connect (OSTI)

    Anderson, Johan; Nordman, Hans [Department of Earth and Space Sciences, Chalmers University of Technology, SE-412 96 Goeteborg (Sweden); Singh, Raghvendra; Kaw, Predhiman [Institute for Plasma Research, Bhat, Gandhinagar, Gujarat 382428 (India)

    2012-08-15T23:59:59.000Z

    In this work, the first demonstration of an electron branch of the geodesic acoustic mode (el-GAM) driven by electron temperature gradient (ETG) modes is presented. The work is based on a fluid description of the ETG mode retaining non-adiabatic ions and the dispersion relation for el-GAMs driven nonlinearly by ETG modes is derived. A new saturation mechanism for ETG turbulence through the interaction with el-GAMs is found, resulting in a significantly enhanced ETG turbulence saturation level compared to the mixing length estimate.

  19. Pulse atmospheric fluidized bed combustion

    SciTech Connect (OSTI)

    Not Available

    1989-03-01T23:59:59.000Z

    The overall objective of the program is the development of a pulsed atmospheric fluidized-bed combustion (PAFBC) technology to burn coal and to provide heat and steam to commercial, institutional, and small industrial applications at a reasonable price in an environmentally acceptable manner. During this reporting period, a total of eight shakedown and debugging coal combustion tests were performed in the AFBC. A start-up procedure was established, system improvements implemented, and preliminary material and heat balances made based on these tests. The pulse combustor for the AFBC system was fabricated and installed and a series of tests was conducted on the system. 17 figs., 5 tabs.

  20. Mixed Mode Matrix Multiplication

    SciTech Connect (OSTI)

    Meng-Shiou Wu; Srinivas Aluru; Ricky A. Kendall

    2004-09-30T23:59:59.000Z

    In modern clustering environments where the memory hierarchy has many layers (distributed memory, shared memory layer, cache,...), an important question is how to fully utilize all available resources and identify the most dominant layer in certain computations. When combining algorithms on all layers together, what would be the best method to get the best performance out of all the resources we have? Mixed mode programming model that uses thread programming on the shared memory layer and message passing programming on the distributed memory layer is a method that many researchers are using to utilize the memory resources. In this paper, they take an algorithmic approach that uses matrix multiplication as a tool to show how cache algorithms affect the performance of both shared memory and distributed memory algorithms. They show that with good underlying cache algorithm, overall performance is stable. When underlying cache algorithm is bad, superlinear speedup may occur, and an increasing number of threads may also improve performance.

  1. Pulsed electrodeposition of iron-nickel alloys

    SciTech Connect (OSTI)

    Grimmett, D.L.; Schwartz, M.; Nobe, K. (Dept. of Chemical Engineering, Univ. of California, Los Angeles, CA (US))

    1990-11-01T23:59:59.000Z

    This paper reports on the effects of dc, pulse, and pulse reverse current waveforms on deposition of Fe-Ni alloys studied in unagitated solutions and with a rotating cylindrical electrode. A nickel sulfamate/ferrous chloride electrolyte system at pH 2 less than 2 A/dm{sup 2}. Pulse reverse plating led to a decrease in anomalous deposition at low current densities. Rotating cylindrical electrodes indicated significant mass transfer effects at high current densities. During pulse reverse plating an increase in anodic pulse magnitude decreased anomalous deposition; pulse frequency had its greatest effect in reducing anomalous deposition between 100 and 300 Hz.

  2. Demonstration of coherent time-frequency Schmidt mode selection using dispersion-engineered frequency conversion

    E-Print Network [OSTI]

    Benjamin Brecht; Andreas Eckstein; Raimund Ricken; Viktor Quiring; Hubertus Suche; Linda Sansoni; Christine Silberhorn

    2014-09-16T23:59:59.000Z

    Time-frequency Schmidt (TFS) modes of ultrafast quantum states are naturally compatible with high bit-rate integrated quantum communication networks. Thus they offer an attractive alternative for the realization of high dimensional quantum optics. Here, we present a quantum pulse gate based on dispersion-engineered ultrafast frequency conversion in a nonlinear optical waveguide, which is a key element for harnessing the potential of TFS modes. We experimentally retrieve the modal spectral-temporal structure of our device and demonstrate a single-mode operation fidelity of 80\\%, which is limited by experimental shortcomings. In addition, we retrieve a conversion efficiency of 87.7\\% with a high signal-to-noise ratio of 8.8 when operating the quantum pulse gate at the single-photon level.

  3. Attosecond X-Ray Pulses for Molecular Electronic Dynamics

    E-Print Network [OSTI]

    Abel, Mark Joseph

    2010-01-01T23:59:59.000Z

    techniques for ultrafast laser pulse characterization. Thethe ultrafast evolution of the driver pulse intensity, weisolated pulse production will enable probing of ultrafast

  4. Recent advances in long-pulse high-confinement plasma operations in Experimental Advanced Superconducting Tokamak

    SciTech Connect (OSTI)

    Guo, H. Y. [Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, Hefei 230031 (China) [Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, Hefei 230031 (China); Tri Alpha Energy, Inc., P.O. Box 7010, Rancho Santa Margarita, California 92688 (United States); Li, J.; Wan, B. N., E-mail: bnwan@ipp.ac.cn; Gong, X. Z.; Xu, G. S.; Zhang, X. D.; Ding, S. Y.; Gan, K. F.; Hu, J. S.; Hu, L. Q.; Liu, S. C.; Qian, J. P.; Sun, Y. W.; Wang, H. Q.; Wang, L.; Xia, T. Y.; Xiao, B. J.; Zeng, L.; Zhao, Y. P. [Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, Hefei 230031 (China)] [Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, Hefei 230031 (China); and others

    2014-05-15T23:59:59.000Z

    A long-pulse high confinement plasma regime known as H-mode is achieved in the Experimental Advanced Superconducting Tokamak (EAST) with a record duration over 30?s, sustained by Lower Hybrid wave Current Drive (LHCD) with advanced lithium wall conditioning and divertor pumping. This long-pulse H-mode plasma regime is characterized by the co-existence of a small Magneto-Hydrodynamic (MHD) instability, i.e., Edge Localized Modes (ELMs) and a continuous quasi-coherent MHD mode at the edge. We find that LHCD provides an intrinsic boundary control for ELMs, leading to a dramatic reduction in the transient power load on the vessel wall, compared to the standard Type I ELMs. LHCD also induces edge plasma ergodization, broadening heat deposition footprints, and the heat transport caused by ergodization can be actively controlled by regulating edge plasma conditions, thus providing a new means for stationary heat flux control. In addition, advanced tokamak scenarios have been newly developed for high-performance long-pulse plasma operations in the next EAST experimental campaign.

  5. Multiple colliding electromagnetic pulses: a way to lower the threshold of $e^+e^-$ pair production from vacuum

    E-Print Network [OSTI]

    S. S. Bulanov; V. D. Mur; N. B. Narozhny; J. Nees; V. S. Popov

    2010-03-12T23:59:59.000Z

    The scheme of simultaneous multiple pulse focusing on one spot naturally arises from the structural features of projected new laser systems, such as ELI and HiPER. It is shown that the multiple pulse configuration is beneficial for observing $e^+e^-$ pair production from vacuum under the action of sufficiently strong electromagnetic fields. The field of the focused pulses is described using a realistic three-dimensional model based on an exact solution of the Maxwell equations. The $e^+e^-$ pair production threshold in terms of electromagnetic field energy can be substantially lowered if, instead of one or even two colliding pulses, multiple pulses focused on one spot are used. The multiple pulse interaction geometry gives rise to subwavelength field features in the focal region. These features result in the production of extremely short $e^+e^-$ bunches.

  6. Developing high energy mode-locked fiber laser at 2 micron

    E-Print Network [OSTI]

    Huang, C; Shang, W; Tang, Y; Xu, J

    2015-01-01T23:59:59.000Z

    While dissipative soliton operation has successfully improved the pulse energy of 1 {\\mu}m and 1.5 {\\mu}m fiber lasers to tens of nanojoules, it is still hard to scale the pulse energy of dissipative solitons at 2 {\\mu}m due to the anomalous dispersion of the gain fiber. Based on theoretical simulation, we analyze intracavity dynamics of dissipative solitons (DSs) and propose that gain fiber should be condensed to short length in order to scale the pulse energy of 2 {\\mu}m DSs. The simulation predicts pulse energy of over 10 nJ for 2 {\\mu}m dissipative solitons, comparable to that achieved in the 1 {\\mu}m and 1.5 {\\mu}m regimes. Experimental operation generates stable 2 {\\mu}m DSs from a linear cavity with pulse energy of 4.9 nJ and dechirped pulse duration of 579 fs. These results advance our understanding of mode-locked fiber laser at different wavelengths and lay an important step in achieving high energy ultrafast laser pulses from anomalous dispersion gain media at 2 {\\mu}m.

  7. ICE Pulse Oximeter Smart Alarm App Requirements

    E-Print Network [OSTI]

    Huth, Michael

    ICE Pulse Oximeter Smart Alarm App Requirements 6 March 2012 Revision 0 for an Integrated Clinical Environment (ICE) pulse oximetry monitoring app that provides.2 References [Purpose: List all ICE standards, and other standards and references

  8. Novette pulse-power-system description

    SciTech Connect (OSTI)

    Gritton, D.G.; Christie, D.J.; Holloway, R.W.; Merritt, B.T.; Oicles, J.A.; Whitham, K.; Wilcox, R.B.

    1983-01-01T23:59:59.000Z

    This paper is a summary of the pulse power systems for Novette; the flashlamp power system, the pulsers for the various optical shutters and the pulse power control system.

  9. Dispersion compensation in chirped pulse amplification systems

    DOE Patents [OSTI]

    Bayramian, Andrew James; Molander, William A.

    2014-07-15T23:59:59.000Z

    A chirped pulse amplification system includes a laser source providing an input laser pulse along an optical path. The input laser pulse is characterized by a first temporal duration. The system also includes a multi-pass pulse stretcher disposed along the optical path. The multi-pass pulse stretcher includes a first set of mirrors operable to receive input light in a first plane and output light in a second plane parallel to the first plane and a first diffraction grating. The pulse stretcher also includes a second set of mirrors operable to receive light diffracted from the first diffraction grating and a second diffraction grating. The pulse stretcher further includes a reflective element operable to reflect light diffracted from the second diffraction grating. The system further includes an amplifier, a pulse compressor, and a passive dispersion compensator disposed along the optical path.

  10. Voltage controlled MESFET pulse shape generator

    SciTech Connect (OSTI)

    Burkhart, S.C.

    1994-10-26T23:59:59.000Z

    A programmable pulse shape generator capable of producing pulse shapes for Nova and Beamlet has been designed and simulated using the circuit code SPICE. The design utilizes power MESFETS, which are commonly used in microwave amplifiers. The pulse shape is varied by setting a bias voltage on each in a chain of MESFETS with a 200 ps temporal resolution. The electrical pulse then drives an integrated electro-optic modulator similar to what is on Beamlet. Pulse shapes 22 and 25, used on Nova, have been generated by this design. There is no fundamental barrier to making such a pulse generator for use on the National Ignition Facility. In fact, the longer time scales on the NIF pulse will ease the high speed requirements of the pulse shape generator allowing the use of less expensive components. The next step will be to build a prototype circuit for initial testing on Beamlet and Nova.

  11. for Pulsed Power & erElectronics|Texas

    E-Print Network [OSTI]

    Gelfond, Michael

    for Pulsed Power and Power Electronics The Center for Pulsed Power and Power Electronics started as a Plasma research group at Texas Tech University in 1966. The initial work was concerned with har- monic ion

  12. Controlling the nuclear polarization in quantum dots using optical pulses with a modest bandwidth

    E-Print Network [OSTI]

    S. G. Carter; Sophia E. Economou; A. Shabaev; A. S. Bracker

    2011-02-02T23:59:59.000Z

    We show that detuned optical pulse trains with a modest spectral width can polarize nuclear spins in InAs quantum dots. The pulse bandwidth is large enough to excite a coherent superposition of both electron spin eigenstates in these negatively charged dots but narrow enough to give partial spectral selectivity between the eigenstates. The coherent precession of electron spin states and periodic excitation focuses the nuclear spin distribution, producing a discrete set of precession modes. The spectral selectivity generates a net nuclear polarization, through a mechanism that relies on optical spin rotations rather than electron spin relaxation.

  13. Generation of terahertz radiation from a low-density plasma slab irradiated by a laser pulse

    SciTech Connect (OSTI)

    Frolov, A. A. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)

    2010-04-15T23:59:59.000Z

    The generation of terahertz electromagnetic radiation when a laser pulse propagates through a low-density plasma slab is considered. It is shown that terahertz waves are excited because of the growth of a weakly damped, antisymmetric leaking mode of the plasma slab. The spectral, angular, and energy parameters of the terahertz radiation are investigated, as well as the spatiotemporal structure of the emitted waves. It is demonstrated that terahertz electromagnetic wave fields are generated most efficiently when the pulse length is comparable to the slab thickness.

  14. Photon number squeezing of ultra-broadband laser pulses generated by microstructure fibers

    E-Print Network [OSTI]

    K. Hirosawa; H. Furumochi; A. Tada; F. Kannari; M. Takeoka; M. Sasaki

    2005-01-10T23:59:59.000Z

    To the best of our knowledge, we demonstrate for the first time the generation of photon number squeezing by spectral filtering for ultra-broadband light generated by microstructure fibers at 800 nm. A maximum squeezing of 4.6 dB is observed, corresponding to 10.3 dB after correcting for detection losses. We numerically analyzed the quantum dynamics of ultrashort laser pulse propagation through optical fibers by solving a nonlinear quantum Schrodinger equation that included Raman scattering, especially for the quantum correlation of photon number fluctuation among frequency modes in broadband pulses.

  15. FRACTAL DIMENSION ESTIMATION: EMPIRICAL MODE DECOMPOSITION VERSUS WAVELETS

    E-Print Network [OSTI]

    Gonçalves, Paulo

    FRACTAL DIMENSION ESTIMATION: EMPIRICAL MODE DECOMPOSITION VERSUS WAVELETS Paulo Gonc¸alves INRIA, France. {firstname.lastname}@ens-lyon.fr ABSTRACT We address the problem of fractal dimension estimation motions. Index Terms-- fractal dimension, regularity exponents, wavelet transform, EMD 1. MOTIVATION

  16. Stress Induced Degradation Modes in CIGSS Minimodules (Presentation)

    SciTech Connect (OSTI)

    Kempe, M. D.; Terwilliger, K.; Tarrant, D.

    2008-05-01T23:59:59.000Z

    The experimental objectives of this report are: (1) compare the performance of modules exposed to high temperature and humidity; (2) determine the effects of different encapsulants on long term stability of CIGSS modules; and (3) analyze failure modes to determine areas in need of improvement.

  17. Development of the Long Pulse Negative Ion Source for ITER

    SciTech Connect (OSTI)

    Hemsworth, R.S.; Svensson, L.; Esch, H.P.L. de; Krylov, A.; Massmann, P. [Association EURATOM-CEA, CEA/DSM/DRFC, CEA-Cadarache, 13108 St Paul-lez-Durance (France); Boilson, D. [Association EURATOM-DCU, PRL/NCPST, Glasnevin, Dublin 13 (Ireland); Fanz, U. [Association EURATOM-IPP, Max-Planck-Institut fuer Plasmaphysik D-85748 Garching (Germany); Zaniol, B. [CONSORZIO RFX Association EURATOM-ENEA, Corso Stati Uniti 4, I-35127 Padova (Italy)

    2005-04-06T23:59:59.000Z

    A model of the ion source designed for the neutral beam injectors of the International Thermonuclear Experimental Reactor (ITER), the KAMABOKO III ion source, is being tested on the MANTIS test stand at the DRFC Cadarache in collaboration with JAERI, Japan, who designed and supplied the ion source. The ion source is attached to a 3 grid 30 keV accelerator (also supplied by JAERI) and the accelerated negative ion current is determined from the energy deposited on a calorimeter located 1.6 m from the source.During experiments on MANTIS three adverse effects of long pulse operation were found: The negative ion current to the calorimeter is {approx_equal}50% of that obtained from short pulse operation Increasing the plasma grid (PG) temperature results in {<=}40% enhancement in negative ion yield, substantially below that reported for short pulse operation, {>=}100%. The caesium 'consumption' is up to 1500 times that expected.Results presented here indicate that each of these is, at least partially, explained by thermal effects. Additionally presented are the results of a detailed characterisation of the source, which enable the most efficient mode of operation to be identified.

  18. Mode-locked solid state lasers using diode laser excitation

    DOE Patents [OSTI]

    Holtom, Gary R. (Boston, MA)

    2012-03-06T23:59:59.000Z

    A mode-locked laser employs a coupled-polarization scheme for efficient longitudinal pumping by reshaped laser diode bars. One or more dielectric polarizers are configured to reflect a pumping wavelength having a first polarization and to reflect a lasing wavelength having a second polarization. An asymmetric cavity provides relatively large beam spot sizes in gain medium to permit efficient coupling to a volume pumped by a laser diode bar. The cavity can include a collimation region with a controlled beam spot size for insertion of a saturable absorber and dispersion components. Beam spot size is selected to provide stable mode locking based on Kerr lensing. Pulse durations of less than 100 fs can be achieved in Yb:KGW.

  19. Progress In Understanding The Enhanced Petestal H-mode In NSTX

    SciTech Connect (OSTI)

    Gerhardt, S. P.; Canik, J. M.; Maingi, R.; Battaglia, D.; Bell, R. E.; Guttenfelder, W.; LeBlanc, B. P.; Smith, D. R.; Yuh, H.; Sabbagh, S.

    2014-06-26T23:59:59.000Z

    ThIS paper describes the enhanced pedestal (EP) H-mode observed in the National Spherical Torus Experiment (NSTX). The defining characteristics of EP H-mode are given, namely i)transition after the L- to H-mode transition, ii) region of very steep ion temperature gradient, and iii) associated region of strong rotational shear. A newly observed long-pulse EP H-mode example shows quiescent behavior for as long as the heating and current drive sources are maintained. Cases are shown where the region of steep ion temperature gradient is located at the very edge, and cases where it is shifted up to 10 cm inward from the plasma edge; these cases are united by a common dependence of the ion temperature gradient on the toroidal rotation frequency shear. EP H-mode examples have been observed across a wide range of q95 and pedestal collisionality. No strong changes in the fluctuation amplitudes have been observed following the eP H-mode transition, and transport analysis indicates that the ion t hermal transport is comparable to or less than anticipated from a simple neoclassical transport model. Cases are shown where EP H-modes were reliably generated, through these low-q95 examples were difficult to sustain. A case where an externally triggered ELM precipitates the transition to EP H-mode is also shown, though an initial experiment designed to trigger EP-H-modes in this fashion was successful.

  20. Progress in understanding the enhanced pedestal H-mode in NSTX

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Gerhardt, S.P.; Canik, J.M; Maingi, R.; Battaglia, D.; Bell, R.E.; Guttenfelder, W.; LeBlanc, B.P.; Smith, D.R.; Yuh, H.; Sabbagh, S.

    2014-08-01T23:59:59.000Z

    The paper describes the enhanced pedestal (EP) H-mode observed in the National Spherical Torus Experiment (NSTX). The defining characteristics of EP H-mode are given, namely i)transition after the L- to H-mode transition, ii) region of very steep ion temperature gradient, and iii) associated region of strong rotational shear. A newly observed long-pulse EP H-mode example shows quiescent behavior for as long as the heating and current drive sources are maintained. Cases are shown where the region of steep ion temperature gradient is located at the very edge, and cases where it is shifted up to 10 cm inward from the plasma edge; these cases are united by a common dependence of the ion temperature gradient on the toroidal rotation frequency shear. EP H-mode examples have been observed across a wide range of q95 and pedestal collisionality. No strong changes in the fluctuation amplitudes have been observed following the eP H-mode transition, and transport analysis indicates that the ion t hermal transport is comparable to or less than anticipated from a simple neoclassical transport model. Cases are shown where EP H-modes were reliably generated, through these low-q95 examples were difficult to sustain. A case where an externally triggered ELM precipitates the transition to EP H-mode is also shown, though an initial experiment designed to trigger EP-H-modes in this fashion was successful.

  1. Progress in understanding the enhanced pedestal H-mode in NSTX

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Gerhardt, S.P.; Canik, J.M; Maingi, R.; Battaglia, D.; Bell, R.E.; Guttenfelder, W.; LeBlanc, B.P.; Smith, D.R.; Yuh, H.; Sabbagh, S.

    2014-08-01T23:59:59.000Z

    The paper describes the enhanced pedestal (EP) H-mode observed in the National Spherical Torus Experiment (NSTX). The defining characteristics of EP H-mode are given, namely i)transition after the L- to H-mode transition, ii) region of very steep ion temperature gradient, and iii) associated region of strong rotational shear. A newly observed long-pulse EP H-mode example shows quiescent behavior for as long as the heating and current drive sources are maintained. Cases are shown where the region of steep ion temperature gradient is located at the very edge, and cases where it is shifted up to 10 cm inward from themore »plasma edge; these cases are united by a common dependence of the ion temperature gradient on the toroidal rotation frequency shear. EP H-mode examples have been observed across a wide range of q95 and pedestal collisionality. No strong changes in the fluctuation amplitudes have been observed following the eP H-mode transition, and transport analysis indicates that the ion t hermal transport is comparable to or less than anticipated from a simple neoclassical transport model. Cases are shown where EP H-modes were reliably generated, through these low-q95 examples were difficult to sustain. A case where an externally triggered ELM precipitates the transition to EP H-mode is also shown, though an initial experiment designed to trigger EP-H-modes in this fashion was successful.« less

  2. Femtosecond pulse imaging: ultrafast optical oscilloscope

    E-Print Network [OSTI]

    Fainman, Yeshaiahu

    Femtosecond pulse imaging: ultrafast optical oscilloscope P. C. Sun, Y. T. Mazurenko,* and Y as well as our ability to detect the shape of the ul- trashort pulses that can be seen as an ultrafast 12, 1996 A nonlinear optical processor that is capable of real-time conversion of a femtosecond pulse

  3. High-Pulse-Energy Ultrafast Laser for

    E-Print Network [OSTI]

    Painter, Kevin

    High-Pulse-Energy Ultrafast Laser for Spectroscopy & Micromachining PROBLEM THIS TECHNOLOGY SOLVES. In addition to the OPO, a custom designed ultrafast pump source, provides high pulse energy (.res.hw.ac.uk Professor Derryck Reid (Principal Investigator) www.ultrafast.hw.ac.uk BENEFITS & APPLICATIONS: · High pulse

  4. Optical precursor fields in nonlinear pulse dynamics

    E-Print Network [OSTI]

    Oughstun, Kurt

    . Oughstun and G. C. Sherman, Electromagnetic Pulse Propagation in Causal Dielectrics (Springer-Verlag, Berlin-Heidelberg, 1994). 7. K. E. Oughstun, Electromagnetic and Optical Pulse Propagation1: Spectral, 2009). 9. K. E. Oughstun and G. C. Sherman, "Propagation of electromagnetic pulses in a linear

  5. Hawking radiation and Quasinormal modes

    E-Print Network [OSTI]

    SangChul Yoon

    2005-10-05T23:59:59.000Z

    The spectrum of Hawking radiation by quantum fields in the curved spacetime is continuous, so the explanation of Hawking radiation using quasinormal modes can be suspected to be impossible. We find that quasinormal modes do not explain the relation between the state observed in a region far away from a black hole and the short distance behavior of the state on the horizon.

  6. Mediating Religion: Modes of Communication

    E-Print Network [OSTI]

    Indiana University

    Mediating Religion: Modes of Communication in Religious Contexts Keynote: Dr. Lerone Martin, particularly given recent innovations in mass media and digital communications technologies. Turning attention to modes of communication in religious contexts, this conference will address ways in which mass media have

  7. Higgs as a Top-Mode Pseudo

    E-Print Network [OSTI]

    Hidenori S. Fukano; Masafumi Kurachi; Shinya Matsuzaki; Koichi Yamawaki

    2014-08-18T23:59:59.000Z

    In the spirit of the top quark condensation, we propose a model which has a naturally light composite Higgs boson, "tHiggs", to be identified with the 126 GeV Higgs discovered at the LHC. The tHiggs, a bound state of the top quark and its flavor (vector-like) partner, emerges as a pseudo Nambu-Goldstone boson (NGB), "Top-Mode Pseudo", together with the exact NGBs to be absorbed into the W and Z bosons as well as another (heavier) Top-Mode Pseudo (CP-odd composite scalar). Those five composite (exact/pseudo) NGBs are dynamically produced simultaneously by a single supercritical four-fermion interaction having U(3) x U(1) symmetry which includes the electroweak symmetry, where the vacuum is aligned by small explicit breaking term so as to break the symmetry down to a subgroup, U(2) x U(1)', in a way not to retain the electroweak symmetry, in sharp contrast to the little Higgs models. The explicit breaking term for the vacuum alignment gives rise to a mass of the tHiggs, which is protected by the symmetry and hence naturally controlled against radiative corrections. Realistic top quark mass is easily realized similarly to the top-seesaw mechanism by introducing an extra (subcritical) four-fermion coupling which explicitly breaks the residual U(2) x U(1)' symmetry. We present a phenomenological Lagrangian of the Top-Mode Pseudos along with the standard model particles, which will be useful for the study of the collider phenomenology. The coupling property of the tHiggs is shown to be consistent with the currently available data reported from the LHC. Several phenomenological consequences and constraints from experiments are also addressed.

  8. (Pulsed atmospheric fluidized bed combustion (PAFBC))

    SciTech Connect (OSTI)

    Not Available

    1988-10-01T23:59:59.000Z

    This first Quarterly Technical Progress Report presents the results of work accomplished during the period April 19 through July 24,1988. The overall objective of the program is the development of a pulsed atmospheric fluidized-bed combustion (PAFBC) technology to burn coal and to provide heat and steam to commercial, institutional, and small industrial applications at a reasonable price in an environmentally acceptable manner. the program scope consisted of two tasks; the first was to establish preliminary feasibility by the use of theoretical and state-of-the-art information. This task was completed during the first quarter of the contract period and a topical report entitled, Pulsed Atmospheric Fluidized Bed combustion (PAFBC) - Preliminary Feasibility Study'' was prepared as a decision point to proceed'' deliverable in accordance with the terms of the contract. This first quarterly progress report therefore covers the contract activities subsequent to the approval of the feasibility study and the decision to proceed with the Task 2 effort. As the initial quarterly technical progress report, this document includes a subsection on background which will be omitted in subsequent reports. All effort during this period was devoted to the design and analysis of the PAFBC. Design drawings were prepared and fabrication and procurement initiated. Quotations were evaluated and a fabrication contract awarded. A site adjacent to the MTCI building was chosen for the installation of the PAFBC. Some ancillary components were purchased, renovated, and tested. Some delays in delivery of components have resulted in some schedule delay. It is anticipated that the program pace will accelerate as soon as parts are received and installation and assembly are initiated. 10 figs.,1 tab.

  9. Pulsed Power for Solid-State Lasers

    SciTech Connect (OSTI)

    Gagnon, W; Albrecht, G; Trenholme, J; Newton, M

    2007-04-19T23:59:59.000Z

    Beginning in the early 1970s, a number of research and development efforts were undertaken at U.S. National Laboratories with a goal of developing high power lasers whose characteristics were suitable for investigating the feasibility of laser-driven fusion. A number of different laser systems were developed and tested at ever larger scale in pursuit of the optimum driver for laser fusion experiments. Each of these systems had associated with it a unique pulsed power option. A considerable amount of original and innovative engineering was carried out in support of these options. Ultimately, the Solid-state Laser approach was selected as the optimum driver for the application. Following this, the Laser Program at the Lawrence Livermore National Laboratory and the University of Rochester undertook aggressive efforts directed at developing the technology. In particular, at Lawrence Livermore National Laboratory, a series of laser systems beginning with the Cyclops laser and culminating in the present with the National Ignition Facility were developed and tested. As a result, a large amount of design information for solid-state laser pulsed power systems has been documented. Some of it is in the form of published papers, but most of it is buried in internal memoranda, engineering reports and LLNL annual reports. One of the goals of this book is to gather this information into a single useable format, such that it is easily accessed and understood by other engineers and physicists for use with future designs. It can also serve as a primer, which when seriously studied, makes the subsequent reading of original work and follow-up references considerably easier. While this book deals only with the solid-state laser pulsed power systems, in the bibliography we have included a representative cross section of papers and references from much of the very fine work carried out at other institutions in support of different laser approaches. Finally, in recent years, there has been a renewed interest in high-average-power solid-state glass lasers. Much of the prime power technology developed in support of this has definite applications in the long term for fusion power plant scenarios.

  10. Microwave pulse compression from a storage cavity with laser-induced switching

    DOE Patents [OSTI]

    Bolton, Paul R. (Menlo Park, CA)

    1992-01-01T23:59:59.000Z

    A laser-induced switch and a multiple cavity configuration are disclosed for producing high power microwave pulses. The microwave pulses are well controlled in wavelength and timing, with a quick rise time and a variable shape and power of the pulse. In addition, a method of reducing pre-pulse leakage to a low level is disclosed. Microwave energy is directed coherently to one or more cavities that stores the energy in a single mode, represented as a standing wave pattern. In order to switch the stored microwave energy out of the main cavity and into the branch waveguide, a laser-actuated switch is provided for the cavity. The switch includes a laser, associated optics for delivering the beam into the main cavity, and a switching gas positioned at an antinode in the main cavity. When actuated, the switching gas ionizes, creating a plasma, which becomes reflective to the microwave energy, changing the resonance of the cavity, and as a result the stored microwave energy is abruptly switched out of the cavity. The laser may directly pre-ionize the switching gas, or it may pump an impurity in the switching gas to an energy level which switches when a pre-selected cavity field is attained. Timing of switching the cavities is controlled by varying the pathlength of the actuating laser beam. For example, the pathlengths may be adjusted to output a single pulse of high power, or a series of quick lower power pulses.

  11. Resistive wall mode active control physics design for KSTAR

    SciTech Connect (OSTI)

    Park, Y. S., E-mail: ypark@pppl.gov; Sabbagh, S. A.; Bialek, J. M.; Berkery, J. W. [Department of Applied Physics and Applied Mathematics, Columbia University, New York 10027 (United States)] [Department of Applied Physics and Applied Mathematics, Columbia University, New York 10027 (United States); Bak, J. G.; Lee, S. G.; Oh, Y. K. [National Fusion Research Institute, Daejeon 305-806 (Korea, Republic of)] [National Fusion Research Institute, Daejeon 305-806 (Korea, Republic of)

    2014-01-15T23:59:59.000Z

    As KSTAR H-mode operation approaches the region where the resistive wall mode (RWM) can be unstable, an important issue for future long pulse, high beta plasma operation is to evaluate RWM active feedback control performance using a planned active/passive RWM stabilization system on the device. In particular, an optimal design of feedback sensors allows mode stabilization up to the highest achievable ?{sub N} close to the ideal with-wall limit, ?{sub N}{sup wall}, with reduced control power requirements. The computed ideal n?=?1 mode structure from the DCON code has been input to the VALEN-3D code to calculate the projected performance of an active RWM control system in the KSTAR three-dimensional conducting structure device geometry. Control performance with the midplane locked mode detection sensors, off-midplane saddle loops, and magnetic pickup coils is examined. The midplane sensors measuring the radial component of the mode perturbation is found to be strongly affected by the wall eddy current. The off-axis saddle loops with proper compensation of the prompt applied field are computed to provide stabilization at ?{sub N} up to 86% of ?{sub N}{sup wall} but the low RWM amplitude computed in the off-axis regions near the sensors can produce a low signal-to-noise ratio. The required control power and bandwidth are also estimated with varied noise levels in the feedback sensors. Further improvements have been explored by examining a new RWM sensor design motivated by the off-midplane poloidal magnetic field sensors in NSTX. The new sensors mounted off of the copper passive stabilizer plates near the device midplane show a clear advantage in control performance corresponding to achieving 99% of ?{sub N}{sup wall} without the need of compensation of the prompt field. The result shows a significant improvement of RWM feedback stabilization using the new sensor set which motivates a future feedback sensor upgrade.

  12. Dual amplitude pulse generator for radiation detectors

    DOE Patents [OSTI]

    Hoggan, Jerry M. (Idaho Falls, ID); Kynaston, Ronnie L. (Blackfoot, ID); Johnson, Larry O. (Island Park, ID)

    2001-01-01T23:59:59.000Z

    A pulsing circuit for producing an output signal having a high amplitude pulse and a low amplitude pulse may comprise a current source for providing a high current signal and a low current signal. A gate circuit connected to the current source includes a trigger signal input that is responsive to a first trigger signal and a second trigger signal. The first trigger signal causes the gate circuit to connect the high current signal to a pulse output terminal whereas the second trigger signal causes the gate circuit to connect the low current signal to the pulse output terminal.

  13. 140 GHz pulsed Fourier transform microwave spectrometer

    DOE Patents [OSTI]

    Kolbe, W.F.; Leskovar, B.

    1985-07-29T23:59:59.000Z

    A high frequency energy pulsing system suitable for use in a pulsed microwave spectrometer, including means for generating a high frequency carrier signal, and means for generating a low frequency modulating signal. The carrier signal is continuously fed to a modulator and the modulating signal is fed through a pulse switch to the modulator. When the pulse switch is on, the modulator will produce sideband signals above and below the carrier signal frequency. A frequency-responsive device is tuned to one of the sideband signals and sway from the carrier frequency so that the high frequency energization of the frequency-responsive device is controlled by the pulse switch.

  14. Ion Acceleration by Short Chirped Laser Pulses

    E-Print Network [OSTI]

    Li, Jian-Xing; Keitel, Christoph H; Harman, Zoltán

    2015-01-01T23:59:59.000Z

    Direct laser acceleration of ions by short frequency-chirped laser pulses is investigated theoretically. We demonstrate that intense beams of ions with a kinetic energy broadening of about 1 % can be generated. The chirping of the laser pulse allows the particles to gain kinetic energies of hundreds of MeVs, which is required for hadron cancer therapy, from pulses of energies of the order of 100 J. It is shown that few-cycle chirped pulses can accelerate ions more efficiently than long ones, i.e. higher ion kinetic energies are reached with the same amount of total electromagnetic pulse energy.

  15. Intrinsic chirp of single-cycle pulses

    SciTech Connect (OSTI)

    Lin Qiang; Zheng Jian [Institute of Optics, Department of Physics, Zhejiang University, Hangzhou 310027 (China); Dai Jianming; Ho, I-Chen; Zhang, X.-C. [Center for Terahertz Research, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)

    2010-04-15T23:59:59.000Z

    The Fourier transform-limited electromagnetic pulse has been regarded to be free of chirps for a long time. This is no longer true if the pulse duration goes down to or less than one optical cycle. We report the experimental observation of intrinsic chirps in such pulses with the sub-single-cycle terahertz (THz) waveforms obtained with a standard THz time-domain spectroscopy system. The results confirm the break down of the carrier-envelope (CE) expression for single-cycle optical pulses, and may influence the experimental measurements and theoretical modeling with single-cycle pulses.

  16. Adaptive control system for pulsed megawatt klystrons

    DOE Patents [OSTI]

    Bolie, Victor W. (Albuquerque, NM)

    1992-01-01T23:59:59.000Z

    The invention provides an arrangement for reducing waveform errors such as errors in phase or amplitude in output pulses produced by pulsed power output devices such as klystrons by generating an error voltage representing the extent of error still present in the trailing edge of the previous output pulse, using the error voltage to provide a stored control voltage, and applying the stored control voltage to the pulsed power output device to limit the extent of error in the leading edge of the next output pulse.

  17. Multi-mode Energy Management for Multi-tier Server Tibor Horvath

    E-Print Network [OSTI]

    Skadron, Kevin

    Multi-mode Energy Management for Multi-tier Server Clusters Tibor Horvath tibor Charlottesville, VA 22904 ABSTRACT This paper presents an energy management policy for recon- figurable clusters General Terms Algorithms, Design, Experimentation, Management, Perfor- mance Keywords energy management

  18. Sliding Mode Power Control of Variable Speed Wind Energy Conversion Systems

    E-Print Network [OSTI]

    Boyer, Edmond

    Sliding Mode Power Control of Variable Speed Wind Energy Conversion Systems B. Beltran, T. Ahmed power generation in variable speed wind energy conversion systems (VS-WECS). These systems have two variations. Index Terms--Wind energy conversion system, power generation control, sliding mode control

  19. Radiative Transfer of Sound Waves in a Random Flow: Turbulent Scattering and ModeCoupling

    E-Print Network [OSTI]

    Ryzhik, Lenya

    Radiative Transfer of Sound Waves in a Random Flow: Turbulent Scattering and Mode­Coupling Albert the sound wave propagation in a random flow, whose mean flow is large compared with its fluctuation and the turbulent scattering and mode­coupling of sound waves. We show that, because of the flow­straining term

  20. Unsplit bipolar pulse forming line

    DOE Patents [OSTI]

    Rhodes, Mark A. (Pleasanton, CA)

    2011-05-24T23:59:59.000Z

    A bipolar pulse forming transmission line module and system for linear induction accelerators having first, second, third, and fourth planar conductors which form a sequentially arranged interleaved stack having opposing first and second ends, with dielectric layers between the conductors. The first and second planar conductors are connected to each other at the first end, and the first and fourth planar conductors are connected to each other at the second end via a shorting plate. The third planar conductor is electrically connectable to a high voltage source, and an internal switch functions to short at the first end a high voltage from the third planar conductor to the fourth planar conductor to produce a bipolar pulse at the acceleration axis with a zero net time integral. Improved access to the switch is enabled by an aperture through the shorting plate and the proximity of the aperture to the switch.

  1. Pulsed Power Driven Fusion Energy

    SciTech Connect (OSTI)

    SLUTZ,STEPHEN A.

    1999-11-22T23:59:59.000Z

    Pulsed power is a robust and inexpensive technology for obtaining high powers. Considerable progress has been made on developing light ion beams as a means of transporting this power to inertial fusion capsules. However, further progress is hampered by the lack of an adequate ion source. Alternatively, z-pinches can efficiently convert pulsed power into thermal radiation, which can be used to drive an inertial fusion capsule. However, a z-pinch driven fusion explosion will destroy a portion of the transmission line that delivers the electrical power to the z-pinch. They investigate several options for providing standoff for z-pinch driven fusion. Recyclable Transmission Lines (RTLs) appear to be the most promising approach.

  2. Understanding and Improving High Voltage Vacuum Insulators for Microsecond Pulses

    SciTech Connect (OSTI)

    Javedani, J B; Goerz, D A; Houck, T L; Lauer, E J; Speer, R D; Tully, L K; Vogtlin, G E; White, A D

    2007-03-05T23:59:59.000Z

    High voltage insulation is one of the main areas of pulsed power research and development, and dielectric breakdown is usually the limiting factor in attaining the highest possible performance in pulsed power devices. For many applications the delivery of pulsed power into a vacuum region is the most critical aspect of operation. The surface of an insulator exposed to vacuum can fail electrically at an applied field more than an order or magnitude below the bulk dielectric strength of the insulator. This mode of breakdown, called surface flashover, imposes serious limitations on the power flow into a vacuum region. This is especially troublesome for applications where high voltage conditioning of the insulator and electrodes is not practical and for applications where relatively long pulses, on the order of several microseconds, are required. The goal of this project is to establish a sound fundamental understanding of the mechanisms that lead to surface flashover, and then evaluate the most promising techniques to improve vacuum insulators and enable high voltage operation at stress levels near the intrinsic bulk breakdown limits of the material. The approach we proposed and followed was to develop this understanding through a combination of theoretical and computation methods coupled with experiments to validate and quantify expected behaviors. In this report we summarize our modeling and simulation efforts, theoretical studies, and experimental investigations. The computational work began by exploring the limits of commercially available codes and demonstrating methods to examine field enhancements and defect mechanisms at microscopic levels. Plasma simulations with particle codes used in conjunction with circuit models of the experimental apparatus enabled comparisons with experimental measurements. The large scale plasma (LSP) particle-in-cell (PIC) code was run on multiprocessor platforms and used to simulate expanding plasma conditions in vacuum gap regions. Algorithms were incorporated into LSP to handle secondary electron emission from dielectric materials to enable detailed simulations of flashover phenomenon. Theoretical studies were focused on explaining a possible mechanism for anode initiated surface flashover that involves an electron avalanche process starting near the anode, not a mechanism involving bulk dielectric breakdown. Experiments were performed in Engineering's Pulsed Power Lab using an available 100-kV, 10-{micro}s pulse generator and vacuum chamber. The initial experiments were done with polyethylene insulator material in the shape of a truncated cone cut at +45{sup o} angle between flat electrodes with a gap of 1.0 cm. The insulator was sized so there were no flashovers or breakdowns under nominal operating conditions. Insulator flashover or gap closure was induced by introducing a plasma source, a tuft of velvet, in proximity to the insulator or electrode.

  3. Solid state pulsed power generator

    DOE Patents [OSTI]

    Tao, Fengfeng; Saddoughi, Seyed Gholamali; Herbon, John Thomas

    2014-02-11T23:59:59.000Z

    A power generator includes one or more full bridge inverter modules coupled to a semiconductor opening switch (SOS) through an inductive resonant branch. Each module includes a plurality of switches that are switched in a fashion causing the one or more full bridge inverter modules to drive the semiconductor opening switch SOS through the resonant circuit to generate pulses to a load connected in parallel with the SOS.

  4. Synthesis of nanostructured SiC using the pulsed laser deposition technique

    SciTech Connect (OSTI)

    Zhang, H.X. [Institute for Functional Nanomaterials, University of Puerto Rico, San Juan, PR 00931 (United States); Department of Physics, University of Puerto Rico, P.O. Box 23343, San Juan, PR 00931 (United States); Feng, P.X. [Institute for Functional Nanomaterials, University of Puerto Rico, San Juan, PR 00931 (Puerto Rico); Department of Physics, University of Puerto Rico, P.O. Box 23343, San Juan, PR 00931 (Puerto Rico)], E-mail: peterxianping@vmail.uprrp.edu; Makarov, V.; Weiner, B.R. [Institute for Functional Nanomaterials, University of Puerto Rico, San Juan, PR 00931 (Puerto Rico); Department of Chemistry, University of Puerto Rico, P.O. Box 23346, San Juan, PR 00931 (Puerto Rico); Morell, G. [Institute for Functional Nanomaterials, University of Puerto Rico, San Juan, PR 00931 (Puerto Rico); Department of Physics, University of Puerto Rico, P.O. Box 23343, San Juan, PR 00931 (Puerto Rico)

    2009-01-08T23:59:59.000Z

    We report the new results on the direct synthesis of nanostructured silicon carbide (SiC) materials using the pulsed laser deposition technique. Scanning electron microscopy images revealed that SiC nanoholes, nanosprouts, nanowires, and nanoneedles were obtained. The crystallographic structure, chemical composition, and bond structure of the nanoscale SiC materials were investigated using X-ray diffraction, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and Raman scattering spectroscopy. The transverse optical mode and longitudinal optical mode in Raman spectra were found to become sharper as the substrate temperature was increased, while the material structure evolved from amorphous to crystalline.

  5. Multi-mode radio frequency device

    DOE Patents [OSTI]

    Gilbert, Ronald W. (Morgan Hill, CA); Carrender, Curtis Lee (Morgan Hill, CA); Anderson, Gordon A. (Benton City, WA); Steele, Kerry D. (Kennewick, WA)

    2007-02-13T23:59:59.000Z

    A transponder device having multiple modes of operation, such as an active mode and a passive mode, wherein the modes of operation are selected in response to the strength of a received radio frequency signal. A communication system is also provided having a transceiver configured to transmit a radio frequency signal and to receive a responsive signal, and a transponder configured to operate in a plurality of modes and to activate modes of operation in response to the radio frequency signal. Ideally, each mode of operation is activated and deactivated independent of the other modes, although two or more modes may be concurrently operational.

  6. Efficient Photoionization-Loading of Trapped Cadmium Ions with Ultrafast Pulses

    E-Print Network [OSTI]

    L. Deslauriers; M. Acton; B. B. Blinov; K. -A. Brickman; P. C. Haljan; W. K. Hensinger; D. Hucul; S. Katnik; R. N. Kohn, Jr.; P. J. Lee; M. J. Madsen; P. Maunz; S. Olmschenk; D. L. Moehring; D. Stick; J. Sterk; M. Yeo; K. C. Younge; C. Monroe

    2006-08-04T23:59:59.000Z

    Atomic cadmium ions are loaded into radiofrequency ion traps by photoionization of atoms in a cadmium vapor with ultrafast laser pulses. The photoionization is driven through an intermediate atomic resonance with a frequency-quadrupled mode-locked Ti:Sapphire laser that produces pulses of either 100 fsec or 1 psec duration at a central wavelength of 229 nm. The large bandwidth of the pulses photoionizes all velocity classes of the Cd vapor, resulting in high loading efficiencies compared to previous ion trap loading techniques. Measured loading rates are compared with a simple theoretical model, and we conclude that this technique can potentially ionize every atom traversing the laser beam within the trapping volume. This may allow the operation of ion traps with lower levels of background pressures and less trap electrode surface contamination. The technique and laser system reported here should be applicable to loading most laser-cooled ion species.

  7. Operation conditions for a picosecond laser with an aberration thermal lens under longitudinal pulsed diode pumping

    SciTech Connect (OSTI)

    Morozov, V B; Olenin, A N; Tunkin, V G; Yakovlev, D V

    2011-06-30T23:59:59.000Z

    The dependence of the repetition frequency range that provides stable operation of a picosecond laser with longitudinal pulsed diode pumping on the parameters of the laser cavity and the thermal lens induced in the active element is analysed. The results of calculating the radius of the lower cavity mode as a function of pump beam average power and diameter are reported. Based on the measurements by the probe-beam method, the adequacy of the presented model of aberration thermal lens is demonstrated for the cases of uniformly doped Nd:YAG and composite YAG/Nd:YAG active elements upon tuning the pump pulse repetition frequency within the range of 0 - 1 kHz. The ways for implementing stable generation of millijoule pulses in a specified repetition frequency range are discussed. (control of laser radiation parameters)

  8. Mode transition of a Hall thruster discharge plasma

    SciTech Connect (OSTI)

    Hara, Kentaro, E-mail: kenhara@umich.edu; Sekerak, Michael J., E-mail: msekerak@umich.edu; Boyd, Iain D.; Gallimore, Alec D. [University of Michigan, Ann Arbor, Michigan 48109 (United States)

    2014-05-28T23:59:59.000Z

    A Hall thruster is a cross-field plasma device used for spacecraft propulsion. An important unresolved issue in the development of Hall thrusters concerns the effect of discharge oscillations in the range of 10–30?kHz on their performance. The use of a high speed Langmuir probe system and ultra-fast imaging of the discharge plasma of a Hall thruster suggests that the discharge oscillation mode, often called the breathing mode, is strongly correlated to an axial global ionization mode. Stabilization of the global oscillation mode is achieved as the magnetic field is increased and azimuthally rotating spokes are observed. A hybrid-direct kinetic simulation that takes into account the transport of electronically excited atoms is used to model the discharge plasma of a Hall thruster. The predicted mode transition agrees with experiments in terms of the mean discharge current, the amplitude of discharge current oscillation, and the breathing mode frequency. It is observed that the stabilization of the global oscillation mode is associated with reduced electron transport that suppresses the ionization process inside the channel. As the Joule heating balances the other loss terms including the effects of wall loss and inelastic collisions, the ionization oscillation is damped, and the discharge oscillation stabilizes. A wide range of the stable operation is supported by the formation of a space charge saturated sheath that stabilizes the electron axial drift and balances the Joule heating as the magnetic field increases. Finally, it is indicated from the numerical results that there is a strong correlation between the emitted light intensity and the discharge current.

  9. Nonlinear excitation of photonikos and plasmons by high-power, short pulse lasers

    E-Print Network [OSTI]

    Levan N. Tsintsadze; Hitoshi Hojo

    2008-10-29T23:59:59.000Z

    Modulational excitation of longitudinal photons (photonikos) and electron Langmuir waves, as well as ion sound waves by an incoherent strong and superstrong radiation (high-power short pulse lasers, non-thermal equilibrium cosmic field radiation, etc.) in plasmas are investigated. A simultaneous generation of photonikos and plasmons are demonstrated. Furthermore, the kinetic instability is considered when a low frequency photonikos are generated alone. Growth rates of these new modes are obtained.

  10. Vibrational Modes of Adsorbed Atoms

    E-Print Network [OSTI]

    LAWRENCE, WR; Allen, Roland E.

    1977-01-01T23:59:59.000Z

    of adsorbed atoms. vi rational modes *Present address: S h University of H c ool of Scienc City, Tex. ouston at Clear La ', r e e and Technology Lake City, Clea Lak %. R. wrence and R. E. Allen published). Allen, Phys. Rev. B (to be 2G. P... are about t r Ne on Kr. The d ou he same as fo mode labeled 2V a as large in the f' t X is almost erst (adsorbate) la e od( b t t)l pure surface mod e ayer. The 1H mode at X is a 4, this mode bec m e. Just to the r'right of X in Fig. e ecomes a...

  11. Pulse Tidal formerly Pulse Generation | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov You are being directedAnnualProperty Edit with form History Facebook icon TwitterZip JumpProwindPuda Coal IncPulse Tidal

  12. A Pulsational Model for the Orthogonal Polarization Modes in Radio Pulsars

    E-Print Network [OSTI]

    J. Christopher Clemens; R. Rosen

    2008-02-17T23:59:59.000Z

    In an earlier paper, we introduced a model for pulsars in which non-radial oscillations of high spherical degree (\\el) aligned to the magnetic axis of a spinning neutron star were able to reproduce subpulses like those observed in single-pulse measurements of pulsar intensity. The model did not address polarization, which is an integral part of pulsar emission. Observations show that many pulsars emit radio waves that appear to be the superposition of two linearly polarized emission modes with orthogonal polarization angles. In this paper, we extend our model to incorporate linear polarization. As before, we propose that pulsational displacements of stellar material modulate the pulsar emission, but now we apply this modulation to a linearly-polarized mode of emission, as might be produced by curvature radiation. We further introduce a second polarization mode, orthogonal to the first, that is modulated by pulsational velocities. We combine these modes in superposition to model the observed Stokes parameters in radio pulsars.

  13. Analysis of the cryogenic system behavior for pulsed heat load in EAST

    SciTech Connect (OSTI)

    Hu, L. B.; Zhuang, M.; Zhou, Z. W.; Xia, G. H. [Cryogenic Engineering Division, Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, Shushanhu Road 350, Hefei, Anhui 230031 (China)

    2014-01-29T23:59:59.000Z

    EAST is the first full superconducting fusion device. The plasma is confined by the magnetic fields generated from a large set of superconducting magnets which are made of cable in-conduit conductor (CICC). In operation, these magnets suffer heat loads from thermal and nuclear radiation from the surrounding components and plasma as well as the eddy currents and the AC losses generated within the magnets, together with the heat conduction through supports and the resistive heat generated at the current lead transiting to room temperature. The cryogenic system of our EAST consists of a 2kW/4K helium refrigerator and a distribution system for the cooling of poloidal field (PF) and toroidal field (TF) coils, structures, thermal shields, buslines and current leads. Pulsed heat load is the main difference between the cryogenic system of a full superconducting Tokamak system and other large scale cryogenic systems. The cryogenic system operates in a pulsed heat loads mode requiring the helium refrigerator to remove periodically large heat loads in time. At the same time, the cryogenic system parameters such as helium cooling superconducting magnets, helium refrigerator and helium distribution system are changing. In this paper, the variation range of the parameters of superconducting magnets and refrigerator has been analyzed in the typical plasma discharge mode. The control scheme for the pulsed loads characteristics of the cryogenic system has been proposed, the implementation of which helps to smooth the pulse loads and to improve the stability of the operation of the cryogenic system.

  14. Pulse

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What's Possible forPortsmouth/Paducah47,193.70COMMUNITY AEROSOL: Shale natural gas proved reserves,Enter

  15. Mixed-Mode Ventilation and Building Retrofits

    E-Print Network [OSTI]

    Brager, Gail; Ackerly, Katie

    2010-01-01T23:59:59.000Z

    Page 15 Mixed-Mode Ventilation and Building RetrofitsEngineers. 2000. Mixed-mode ventilation. CIBSE ApplicationsMichael. 2000. Hybrid Ventilation Systems: An Arup Approach

  16. Occupant satisfaction in mixed-mode buildings.

    E-Print Network [OSTI]

    Brager, Gail; Baker, Lindsay

    2008-01-01T23:59:59.000Z

    Strategies for Mixed-Mode Buildings, Summary Report, CenterCBE). 2006. Website: Mixed-Mode Building Case Studies.Department of Environmental Building Research Establishment

  17. Occupant satisfaction in mixed-mode buildings

    E-Print Network [OSTI]

    Brager, Gail; Baker, Lindsay

    2009-01-01T23:59:59.000Z

    Environmental Quality in Green Buildings”. Indoor Air; 14 (Strategies for Mixed-Mode Buildings, Summary Report, CenterCBE). 2006. Website: Mixed-Mode Building Case Studies.

  18. Age dependent modes of extensional necking instability in soft glassy materials

    E-Print Network [OSTI]

    D. M. Hoyle; S. M. Fielding

    2015-01-07T23:59:59.000Z

    We study the instability to necking of an initially cylindrical filament of soft glassy material subject to extensional stretching. By numerical simulation of the soft glassy rheology model and a simplified fluidity model, and by analytical predictions within a highly generic toy description, we show that the mode of instability is set by the age of the sample relative to the inverse of the applied extensional strain rate. Young samples neck gradually via a liquid-like mode, the onset of which is determined by both the elastic loading and plastic relaxation terms in the stress constitutive equation. Older samples fail at smaller draw ratios via a more rapid mode, the onset of which is determined only by the solid-like elastic loading terms (though plastic effects arise later, once appreciable necking develops). We show this solid-like mode to be the counterpart, for elastoplastic materials, of the Consid\\`ere mode of necking in strain-rate-independent solids.

  19. Pulsed source ion implantation apparatus and method

    DOE Patents [OSTI]

    Leung, Ka-Ngo (Hercules, CA)

    1996-01-01T23:59:59.000Z

    A new pulsed plasma-immersion ion-implantation apparatus that implants ions in large irregularly shaped objects to controllable depth without overheating the target, minimizing voltage breakdown, and using a constant electrical bias applied to the target. Instead of pulsing the voltage applied to the target, the plasma source, for example a tungsten filament or a RF antenna, is pulsed. Both electrically conducting and insulating targets can be implanted.

  20. PULSE DRYING EXPERIMENT AND BURNER CONSTRUCTION

    SciTech Connect (OSTI)

    Robert States

    2006-07-15T23:59:59.000Z

    Non steady impingement heat transfer is measured. Impingement heating consumes 130 T-BTU/Yr in paper drying, but is only 25% thermally efficient. Pulse impingement is experimentally shown to enhance heat transfer by 2.8, and may deliver thermal efficiencies near 85%. Experimental results uncovered heat transfer deviations from steady theory and from previous investigators, indicating the need for further study and a better theoretical framework. The pulse burner is described, and its roll in pulse impingement is analyzed.

  1. Pulsed source ion implantation apparatus and method

    DOE Patents [OSTI]

    Leung, K.N.

    1996-09-24T23:59:59.000Z

    A new pulsed plasma-immersion ion-implantation apparatus that implants ions in large irregularly shaped objects to controllable depth without overheating the target, minimizing voltage breakdown, and using a constant electrical bias applied to the target. Instead of pulsing the voltage applied to the target, the plasma source, for example a tungsten filament or a RF antenna, is pulsed. Both electrically conducting and insulating targets can be implanted. 16 figs.

  2. Ionization by few-cycle pulses: Tracing the electron orbits RID A-7617-2010

    E-Print Network [OSTI]

    Milosevic, D. B.; Paulus, Gerhard G.; Becker, W.

    2005-01-01T23:59:59.000Z

    High-order above-threshold ionization by few-cycle laser pulses is analyzed in terms of quantum orbits. For a given carrier-envelope phase, the number of contributing orbits and their ionization and rescattering times determine the shape...

  3. Subthreshold pair production in short laser pulses

    E-Print Network [OSTI]

    T. Nousch; D. Seipt; B. Kampfer; A. I. Titov

    2012-06-01T23:59:59.000Z

    The $e^+e^-$ pair production by a probe photon traversing a linearly polarized laser pulse is treated as generalized nonlinear Breit-Wheeler process. For short laser pulses with very few oscillations of the electromagnetic field we find below the perturbative weak-field threshold $\\sqrt{s} = 2m$ a similar enhancement of the pair production rate as for circular polarization. The strong subthreshold enhancement is traced back to the finite bandwidth of the laser pulse. A folding model is developed which accounts for the interplay of the frequency spectrum and the intensity distribution in the course of the pulse.

  4. bia-pulse | netl.doe.gov

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    MD PROGRAM PUBLICATIONS Final Reports Pulse Combustor Design Qualification Test and Clean Coal Feedstock Test , Final Report Volume 2: Project Performance and Economics...

  5. Polarization Properties of A Multi-Moded Concentrator

    E-Print Network [OSTI]

    Kogut, A; Hill, R S

    2015-01-01T23:59:59.000Z

    We present the design and performance of a non-imaging concentrator for use in broad-band polarimetry at millimeter through submillimeter wavelengths. A rectangular geometry preserves the input polarization state as the concentrator couples f/2 incident optics to a 2 pi sr detector. Measurements of the co-polar and cross-polar beams in both the few-mode and highly over-moded limits agree with a simple model based on mode truncation. The measured co-polar beam pattern is nearly independent of frequency in both linear polarizations. The cross-polar beam pattern is dominated by a uniform term corresponding to polarization efficiency 94%. After correcting for efficiency, the remaining cross-polar response is -18 dB.

  6. Aperiodic dynamical decoupling sequences in presence of pulse errors

    E-Print Network [OSTI]

    Zhi-Hui Wang; V. V. Dobrovitski

    2011-01-12T23:59:59.000Z

    Dynamical decoupling (DD) is a promising tool for preserving the quantum states of qubits. However, small imperfections in the control pulses can seriously affect the fidelity of decoupling, and qualitatively change the evolution of the controlled system at long times. Using both analytical and numerical tools, we theoretically investigate the effect of the pulse errors accumulation for two aperiodic DD sequences, the Uhrig's DD UDD) protocol [G. S. Uhrig, Phys. Rev. Lett. {\\bf 98}, 100504 (2007)], and the Quadratic DD (QDD) protocol [J. R. West, B. H. Fong and D. A. Lidar, Phys. Rev. Lett {\\bf 104}, 130501 (2010)]. We consider the implementation of these sequences using the electron spins of phosphorus donors in silicon, where DD sequences are applied to suppress dephasing of the donor spins. The dependence of the decoupling fidelity on different initial states of the spins is the focus of our study. We investigate in detail the initial drop in the DD fidelity, and its long-term saturation. We also demonstrate that by applying the control pulses along different directions, the performance of QDD protocols can be noticeably improved, and explain the reason of such an improvement. Our results can be useful for future implementations of the aperiodic decoupling protocols, and for better understanding of the impact of errors on quantum control of spins.

  7. Preliminary Pulsing Experiments to Measure Delayed Neutron Emission Parameters

    SciTech Connect (OSTI)

    Charlton, W.S.; Parish, T.A.; Raman, S.

    1998-10-05T23:59:59.000Z

    Recent interest in delayed neutron parameters including comparisons between macroscopic (experimental) and microscopic (calculated) results have prompted a set of experiments using the 1MW Triga Reactor at the Texas A and M University (TAMU) Nuclear Science Center (NSC) designed to measure the complete set of seven-group delayed neutron parameters for several higher actinides. Operating the Nuclear Science Center Reactor (NSCR) in a pulsed mode, a complete set of delayed neutron parameters were measured for Np-237 and Am-243. The total delayed neutron yield per 100 fissions for Np-237 and Am-243 was found to be 1.14 {+-} 0.07 and 0.85 {+-} 0.05, respectively. Comparisons to previous measurements are made where such measurements are available.

  8. Response of the Hodgkin-Huxley neuron to a periodic sequence of biphasic pulses

    E-Print Network [OSTI]

    Borkowski, L S

    2013-01-01T23:59:59.000Z

    We study the response of the Hodgkin-Huxley neuron stimulated periodically by biphasic rectangular current pulses. The optimal response for charge-balanced input is obtained for cathodic-first pulses with an inter-phase gap (IPG) approximately equal 5 ms. For short pulses the topology of the global bifurcation diagram in the period-amplitude plane is approximately invariant with respect to the pulse polarity and shape details. If stimuli are delivered at neuron's resonant frequencies the firing rate is a continuous function of pulse amplitude. At nonresonant frequencies the quiescent state and the firing state coexist over a range of amplitude values and the transition to excitability is a discontinuous one. There is a multimodal odd-all transition between the 2:1 and 3:1 locked-in states. A strong antiresonant effect is found between the states 3:1 and 4:1, where the modes (2+3n):1, $n=0,1,2,...$, are entirely absent. At high frequencies the excitation threshold is a nonmonotonic function of the stimulus and...

  9. A source of high-power pulses of elliptically polarized ultrawideband radiation

    SciTech Connect (OSTI)

    Andreev, Yu. A., E-mail: andreev@lhfe.hcei.tsc.ru; Efremov, A. M.; Koshelev, V. I.; Kovalchuk, B. M.; Petkun, A. A.; Sukhushin, K. N.; Zorkaltseva, M. Yu. [Institute of High Current Electronics SB RAS, IHCE SB RAS, Tomsk 634055 (Russian Federation)

    2014-10-01T23:59:59.000Z

    Here, we describe a source of high-power ultrawideband radiation with elliptical polarization. The source consisting of a monopolar pulse generator, a bipolar pulse former, and a helical antenna placed into a radioparent container may be used in tests for electromagnetic compatibility. In the source, the helical antenna with the number of turns N = 4 is excited with a high-voltage bipolar pulse. Preliminary, we examined helical antennas at a low-voltage source aiming to select an optimal N and to estimate a radiation center position and boundary of a far-field zone. Finally, characteristics of the source in the operating mode at a pulse repetition rate of 100 Hz are presented in the paper as well. Energy efficiency of the antenna is 0.75 at the axial ratio equal to 1.3. The effective potential of radiation of the source at the voltage amplitudes of the bipolar pulse generator equal to -175/+200 kV reaches 280 kV.

  10. Sub-20-Attosecond Timing Jitter Mode-Locked Fiber Lasers

    E-Print Network [OSTI]

    Kim, Hyoji; Song, Youjian; Yang, Heewon; Shin, Junho; Kim, Chur; Jung, Kwangyun; Wang, Chingyue; Kim, Jungwon

    2014-01-01T23:59:59.000Z

    We demonstrate 14.3-attosecond timing jitter [integrated from 10 kHz to 94 MHz offset frequency] optical pulse trains from 188-MHz repetition-rate mode-locked Yb-fiber lasers. In order to minimize the timing jitter, we shorten the non-gain fiber length to shorten the pulsewidth and reduce excessive higher-order nonlinearity and nonlinear chirp in the fiber laser. The measured jitter spectrum is limited by the amplified spontaneous emission limited quantum noise in the 100 kHz - 1 MHz offset frequency range, while it was limited by the relative intensity noise-converted jitter in the lower offset frequency range. This intrinsically low timing jitter enables sub-100-attosecond synchronization between the two mode-locked Yb-fiber lasers over the full Nyquist frequency with a modest 10-kHz locking bandwidth. The demonstrated performance is the lowest timing jitter measured from any free-running mode-locked fiber lasers, comparable to the performance of the lowest-jitter Ti:sapphire solid-state lasers.

  11. Transmission mode terahertz computed tomography

    DOE Patents [OSTI]

    Ferguson, Bradley Stuart; Wang, Shaohong; Zhang, Xi-Cheng

    2006-10-10T23:59:59.000Z

    A method of obtaining a series of images of a three-dimensional object by transmitting pulsed terahertz (THz) radiation through the entire object from a plurality of angles, optically detecting changes in the transmitted THz radiation using pulsed laser radiation, and constructing a plurality of imaged slices of the three-dimensional object using the detected changes in the transmitted THz radiation. The THz radiation is transmitted through the object as a scanning spot. The object is placed within the Rayleigh range of the focused THz beam and a focusing system is used to transfer the imaging plane from adjacent the object to a desired distance away from the object. A related system is also disclosed.

  12. (pulsed laser deposition, PLD) (ultra-short pulsed laser deposition, uPLD)

    E-Print Network [OSTI]

    (ultra-short pulsed laser deposition, uPLD) PLD (Yttrium barium copper oxide , YBa2Cu3O7-, YBCO) YBCO-2-1 YBCO http://en.wikipedia.org/wiki/File:Ybco002.svg #12;3 1-3 (ultra-short pulsed laser #12;i #12;ii #12;iii #12;iv (pulsed laser deposition, PLD) PLD

  13. One-dimensional full wave simulation on XB mode conversion in electron cyclotron heating

    SciTech Connect (OSTI)

    Kim, S. H., E-mail: shkim95@kaeri.re.kr [Korea Atomic Energy Research Institute, Daejeon 305-353 (Korea, Republic of); Lee, H. Y.; Jo, J. G.; Hwang, Y. S. [Seoul National University, Seoul 151-742 (Korea, Republic of)

    2014-06-15T23:59:59.000Z

    The XB mode conversion in electron cyclotron resonance frequency heating has been studied in detail through 1D full wave simulation. The field pattern depends on the density scale length, and the wave absorption near upper hybrid resonance is maximized beyond the R(X) mode cutoff density for optimized density scale length. The simulated mode conversion efficiency has been compared with that of an analytic formula, showing good agreements except for the phase dependent term of the X wave. The mode conversion efficiency is calculated for oblique injections as well, and it is found that the efficiency decreases as the injection angles increases. Short magnetic field scale length is confirmed to relax the short density scale length condition maximizing the XB mode conversion efficiency. Finally, the simulation code is used to analyze the mode conversion and power absorption of a pre-ionization plasma in versatile experiment spherical torus.

  14. Scissors modes: The first overtone

    SciTech Connect (OSTI)

    Hatada, Keisuke [Instituto de Ciencia de Materiales de Aragon, CSIC-Universidad de Zaragoza, E-50009 Zaragoza (Spain); INFN Laboratori Nazionali di Frascati, c.p. 13, I-00044 Frascati (Italy); Hayakawa, Kuniko [INFN Laboratori Nazionali di Frascati, c.p. 13, I-00044 Frascati (Italy); Centro Fermi, Compendio Viminale, Roma I-00184 (Italy); Palumbo, Fabrizio [INFN Laboratori Nazionali di Frascati, c.p. 13, I-00044 Frascati (Italy)

    2011-07-15T23:59:59.000Z

    Scissors modes were predicted in the framework of the two-rotor model. This model has an intrinsic harmonic spectrum, so that the level above the scissors mode, the first overtone, has excitation energy twice that of the scissors mode. Because the latter is of the order of 3 MeV in the rare-earth region, the energy of the overtone is below threshold for nucleon emission, and its width should remain small enough for the overtone to be observable. We find that B(E2){up_arrow}{sub overtone}=(1/64 {theta}{sub 0}{sup 2})B(E2){up_arrow}{sub scissors}, where {theta}{sub 0} is the zero-point oscillation amplitude, which in the rare-earth region is of order 10{sup -1}.

  15. Design and optimization of 6li neutron-capture pulse mode ion chamber

    E-Print Network [OSTI]

    Chung, Kiwhan

    2009-05-15T23:59:59.000Z

    ........................................ 60 9 Top view of detector matrix for simulation setup...................................... 61 10 HDPE thickness optimization .................................................................... 62 11 Performance of matrix detector... Nonproliferation of the National Nuclear Security Administration (NNSA, 2004) states, ?Detects nuclear proliferation and illicit nuclear and radiological trafficking by conducting cutting-edge research and development?.? More specifically, the need for a neutron...

  16. 10 GHz Colliding Pulse Mode Locked Laser with Electrical and Optical Injection Synchronization

    E-Print Network [OSTI]

    Kolner, Brian H.

    past the 1.15Q waveguiding layer with a methane- hydrogen based reactive ion etching (RIE) process Plasma Enhanced Chemical Vapor Deposition (PECVD) SiO2 layer patterned to mask the 2000 µm x 20 µm active

  17. Maximum relative excitation of a specific vibrational mode via optimum laser-pulse duration

    E-Print Network [OSTI]

    Zhou, Xiang; Lin, Zhibin; Jiang, Chenwei; Gao, Meng; Allen, Roland E.

    2010-01-01T23:59:59.000Z

    , M. Elstner, S. Suhai, Th. Frauen- heim, and R. E. Allen, Phys. Rev. B 64, 153105 #1;2001#2;. 12 G. P. Zhang and T. F. George, Phys. Rev. Lett. 93, 147401 #1;2004#2;; Phys. Rev. B 73, 035422 #1;2006#2;. 13 U. Banin, A. Bartana, S. Ruhman, and R...

  18. Broadband low-dispersion diffraction of femtosecond pulses

    E-Print Network [OSTI]

    Purdue University

    with that of a 100-fs pulse, which is ap- proximately 10 nm (or 5 THz) at 800 nm. The large bandwidths of ultrafast-bit-rate communications.12 Pulse shaping and control of ultrafast pulses are of interest not only from the practical point for femtosecond pulse shaping and ultrafast pulse switch- ing. Bandgap engineered broadband semiconductor MQW

  19. Laser system using ultra-short laser pulses

    DOE Patents [OSTI]

    Dantus, Marcos (Okemos, MI); Lozovoy, Vadim V. (Okemos, MI); Comstock, Matthew (Milford, MI)

    2009-10-27T23:59:59.000Z

    A laser system using ultrashort laser pulses is provided. In another aspect of the present invention, the system includes a laser, pulse shaper and detection device. A further aspect of the present invention employs a femtosecond laser and binary pulse shaping (BPS). Still another aspect of the present invention uses a laser beam pulse, a pulse shaper and a SHG crystal.

  20. Terms and Conditions

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    US) 1 800-333-7638 (Inside US) 1 510-486-7600 (Globally) 1 510-486-7607 (Globally) Report Network Problems: trouble@es.net Provide Web Site Feedback: info@es.net Terms and...

  1. Document Type: Subject Terms

    E-Print Network [OSTI]

    Major, Arkady

    Title: Authors: Source: Document Type: Subject Terms: Abstract: Full Text Word Count: ISSN at creating team results. In fact, it's priceless. Managers in Western corporations have received a lifetime

  2. Sensing mode atomic force microscope

    DOE Patents [OSTI]

    Hough, Paul V. C. (Port Jefferson, NY); Wang, Chengpu (Upton, NY)

    2003-01-01T23:59:59.000Z

    An atomic force microscope utilizes a pulse release system and improved method of operation to minimize contact forces between a probe tip affixed to a flexible cantilever and a specimen being measured. The pulse release system includes a magnetic particle affixed proximate the probe tip and an electromagnetic coil. When energized, the electromagnetic coil generates a magnetic field which applies a driving force on the magnetic particle sufficient to overcome adhesive forces exhibited between the probe tip and specimen. The atomic force microscope includes two independently displaceable piezo elements operable along a Z-axis. A controller drives the first Z-axis piezo element to provide a controlled approach between the probe tip and specimen up to a point of contact between the probe tip and specimen. The controller then drives the first Z-axis piezo element to withdraw the cantilever from the specimen. The controller also activates the pulse release system which drives the probe tip away from the specimen during withdrawal. Following withdrawal, the controller adjusts the height of the second Z-axis piezo element to maintain a substantially constant approach distance between successive samples.

  3. Stability of the splay state in pulse-coupled networks

    SciTech Connect (OSTI)

    Zillmer, Ruediger [Istituto dei Sistemi Complessi, CNR, via Madonna del Piano 10, I-50019 Sesto Fiorentino (Italy); Laboratoire de neurophysique et de physiologie du systeme moteur, CNRS-EP 1848, 45 Rue des Saints-Peres, 75270 Paris (France); INFN Sez. Firenze, via Sansone, 1-I-50019 Sesto Fiorentino (Italy); Livi, Roberto [Dipartimento di Fisica, Universita di Firenze, and Unita INFM via Sansone, 1-I-50019 Sesto Fiorentino (Italy); INFN Sez. Firenze, via Sansone, 1-I-50019 Sesto Fiorentino (Italy); Centro Interdipartimentale per lo Studio delle Dinamiche Complesse, via Sansone, 1-I-50019 Sesto Fiorentino (Italy); Politi, Antonio [Istituto dei Sistemi Complessi, CNR, via Madonna del Piano 10, I-50019 Sesto Fiorentino (Italy); Centro Interdipartimentale per lo Studio delle Dinamiche Complesse, via Sansone, 1-I-50019 Sesto Fiorentino (Italy); Torcini, Alessandro [Istituto dei Sistemi Complessi, CNR, via Madonna del Piano 10, I-50019 Sesto Fiorentino (Italy); INFN Sez. Firenze, via Sansone, 1-I-50019 Sesto Fiorentino (Italy); Centro Interdipartimentale per lo Studio delle Dinamiche Complesse, via Sansone, 1-I-50019 Sesto Fiorentino (Italy)

    2007-10-15T23:59:59.000Z

    The stability of the dynamical states characterized by a uniform firing rate (splay states) is analyzed in a network of globally coupled leaky integrate-and-fire neurons. This is done by reducing the set of differential equations to a map that is investigated in the limit of large network size. We show that the stability of the splay state depends crucially on the ratio between the pulse width and the interspike interval. More precisely, the spectrum of Floquet exponents turns out to consist of three components: (i) one that coincides with the predictions of the mean-field analysis [Abbott and van Vreesvijk, Phys. Rev. E 48, 1483 (1993)], (ii) a component measuring the instability of 'finite-frequency' modes, (iii) a number of 'isolated' eigenvalues that are connected to the characteristics of the single pulse and may give rise to strong instabilities (the Floquet exponent being proportional to the network size). Finally, as a side result, we find that the splay state can be stable even for inhibitory coupling.

  4. SLIM, Short-pulse Technology for High Gradient Induction Accelerators

    SciTech Connect (OSTI)

    Krasnykh, A.; /SLAC; Kardo-Sysoev, A.; /Ioffe Phys. Tech. Inst.; Arntz, F.; /Diversified Tech., Bedford

    2009-12-09T23:59:59.000Z

    The conclusions of this paper are: (1) The gradient of the SLIM-based technology is believed to be achievable in the same range as it is for the gradient of a modern rf-linac technology ({approx}100 MeV per meter). (2) The SLIM concept is based on the nsec TEM pulse mode operation with no laser or rf systems. (3) Main components of SLIM are not stressed while the energy is pumped into the induction system. Components can accept the hard environment conditions such as a radiation dose, mismatch, hard electromagnetic nose level, etc. Only for several nanoseconds the switch is OFF and produces a stress in the induction system. At that time, the delivery of energy to the beam takes place. (4) The energy in the induction system initially is storied in the magnetic field when the switch is ON. That fact makes another benefit: a low voltage power supplies can be used. The reliability of a lower voltage power supply is higher and they are cheaper. (5) The coreless SLIM concept offers to work in the MHz range of repetition rate. The induction system has the high electric efficiency (much higher than the DWA). (6) The array of lined up and activated SLIM cells is believed to be a solid state structure of novel accelerating technology. The electron-hole plasma in the high power solid state structure is precisely controlled by the electromagnetic process of a pulsed power supply.

  5. Cryogenic pellet production developments for long-pulse plasma operation

    SciTech Connect (OSTI)

    Meitner, S. J.; Baylor, L. R.; Combs, S. K.; Fehling, D. T.; McGill, J. M.; Duckworth, R. C.; McGinnis, W. D.; Rasmussen, D. A. [Oak Ridge National Laboratory, 1Bethel Valley Rd Oak Ridge, TN 37831 (United States)

    2014-01-29T23:59:59.000Z

    Long pulse plasma operation on large magnetic fusion devices require multiple forms of cryogenically formed pellets for plasma fueling, on-demand edge localized mode (ELM) triggering, radiative cooling of the divertor, and impurity transport studies. The solid deuterium fueling and ELM triggering pellets can be formed by extrusions created by helium cooled, twin-screw extruder based injection system that freezes deuterium in the screw section. A solenoid actuated cutter mechanism is activated to cut the pellets from the extrusion, inserting them into the barrel, and then fired by the pneumatic valve pulse of high pressure gas. Fuel pellets are injected at a rate up to 10 Hz, and ELM triggering pellets are injected at rates up to 20 Hz. The radiative cooling and impurity transport study pellets are produced by introducing impurity gas into a helium cooled section of a pipe gun where it deposits in-situ. A pneumatic valve is opened and propellant gas is released downstream where it encounters a passive punch which initially accelerates the pellet before the gas flow around the finishes the pellet acceleration. This paper discusses the various cryogenic pellet production techniques based on the twin-screw extruder, pipe gun, and pellet punch designs.

  6. Synchronization Techniques for Burst-Mode Continuous Phase Modulation

    E-Print Network [OSTI]

    Hosseini, Ehsan

    2013-12-31T23:59:59.000Z

    .12 BER for the burst-mode CPM receiver. L0 is the preamble length in terms of data symbols. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 4.1 Phase response q(t) for SOQPSK-MIL (L = 1) and SOQPSK-TG (L = 8). . . . . 86 4.... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 4.5 The computer search results for optimum training sequence for SOQPSK-MIL when L0 = 20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 xii 4.6 The unwrapped phase response of SOQPSK-MIL and SOQPSK-TG schemes...

  7. Stochastic dynamics of collective modes for Brownian dipoles

    E-Print Network [OSTI]

    Leticia F. Cugliandolo; Pierre-Michel Déjardin; Gustavo S. Lozano; Frédéric van Wijland

    2014-12-19T23:59:59.000Z

    The individual motion of a colloidal particle is described by an overdamped Langevin equation. When rotational degrees of freedom are relevant, these are described by a corresponding Langevin process. Our purpose is to show that the microscopic local density of colloids, in terms of a space and rotation state, also evolves according to a Langevin equation. The latter can then be used as the starting point of a variety of approaches, ranging from dynamical density functional theory to mode-coupling approximations.

  8. Pulse-excited, auto-zeroing multiple channel data transmission system

    DOE Patents [OSTI]

    Fasching, George E. (Morgantown, WV)

    1987-01-01T23:59:59.000Z

    A multiple channel data transmission system is provided in which signals from a plurality of pulse operated transducers and a corresponding plurality of pulse operated signal processor channels are multiplexed for single channel FM transmission to a receiving station. The transducers and corresponding channel amplifiers are powered by pulsing the dc battery power to these devices to conserve energy and battery size for long-term data transmission from remote or inaccessible locations. Auto zeroing of the signal channel amplifiers to compensate for drift associated with temperature changes, battery decay, component aging, etc., in each channel is accomplished by means of a unique auto zero feature which between signal pulses holds a zero correction voltage on an integrating capacitor coupled to the corresponding channel amplifier output. Pseudo-continuous outputs for each channel are achieved by pulsed sample-and-hold circuits which are updated at the pulsed operation rate. The sample-and-hold outputs are multiplexed into an FM/FM transmitter for transmission to an FM receiver station for demultiplexing and storage in separate channel recorders.

  9. Pulse-excited, auto-zeroing multiple channel data transmission system

    DOE Patents [OSTI]

    Fasching, G.E.

    1985-02-22T23:59:59.000Z

    A multiple channel data transmission system is provided in which signals from a plurality of pulse operated transducers and a corresponding plurality of pulse operated signal processor channels are multiplexed for single channel FM transmission to a receiving station. The transducers and corresponding channel amplifiers are powered by pulsing the dc battery power to these devices to conserve energy and battery size for long-term data transmission from remote or inaccessible locations. Auto zeroing of the signal channel amplifiers to compensate for drift associated with temperature changes, battery decay, component aging, etc., in each channel is accomplished by means of a unique auto zero feature which between signal pulses holds a zero correction voltage on an integrating capacitor coupled to the corresponding channel amplifier output. Pseudo-continuous outputs for each channel are achieved by pulsed sample-and-hold circuits which are updated at the pulsed operation rate. The sample-and-hold outputs are multiplexed into an FM/FM transmitter for transmission to an FM receiver station for demultiplexing and storage in separate channel recorders.

  10. Stably operating pulse combustor and method

    DOE Patents [OSTI]

    Zinn, Ben T. (Atlanta, GA); Reiner, David (Haifa, IL)

    1990-01-01T23:59:59.000Z

    A pulse combustor apparatus adapted to burn either a liquid fuel or a pulverized solid fuel within a preselected volume of the combustion chamber. The combustion process is substantially restricted to an optimum combustion zone in order to attain effective pulse combustion operation.

  11. Compton Process in Intense Short Laser Pulses

    E-Print Network [OSTI]

    K. Krajewska; J. Z. Kaminski

    2012-06-05T23:59:59.000Z

    The spectra of Compton radiation emitted during electron scattering off an intense laser beam are calculated using the framework of strong-field quantum electrodynamics. We model these intense laser beams as finite length plane-wave-fronted pulses, similar to Neville and Rohrlich [Phys. Rev. D {\\bf 3}, 1692 (1971)], or as trains of such pulses. Expressions for energy and angular distributions of Compton photons are derived such that a comparison of both situations becomes meaningful. Comparing frequency distributions for both an isolated laser pulse and a laser pulse train, we find a very good agreement between the results for long pulse durations which breaks down however for ultrashort laser pulses. The dependence of angular distributions of emitted radiation on a pulse duration is also investigated. Pronounced asymmetries of angular distributions are found for very short laser pulses, which gradually disappear with increasing the number of laser field oscillations. Those asymmetries are attributed to asymmetries of the vector potential describing an incident laser beam.

  12. CenterPulse ContentsDirector's Notes

    E-Print Network [OSTI]

    Wisconsin at Madison, University of

    to our year-in-review newsletter, CenterPulse. Please forward it to your colleagues to help us improveCenterPulse ContentsDirector's Notes 2012 Year in Review Happy New Year, everyone! The year 2012 that recommended full continuation of funding for years 52-56 of NIH support. While the final funding level

  13. Stably operating pulse combustor and method

    DOE Patents [OSTI]

    Zinn, B.T.; Reiner, D.

    1990-05-29T23:59:59.000Z

    A pulse combustor apparatus is described which is adapted to burn either a liquid fuel or a pulverized solid fuel within a preselected volume of the combustion chamber. The combustion process is substantially restricted to an optimum combustion zone in order to attain effective pulse combustion operation. 4 figs.

  14. A programmable Fresnel transform pulse shaper

    E-Print Network [OSTI]

    Purdue University

    A programmable Fresnel transform pulse shaper G. M´inguez-Vega1, J.D. McKinney2 and A.M. Weiner2 1@purdue.edu Abstract: We demonstrate the first reprogrammable Fresnel transform pulse shaper based on a modified direct a free-space Fresnel transform which causes quadratic dispersion of the output temporal waveform. When

  15. Optimization of the LCLS Single Pulse Shutter

    SciTech Connect (OSTI)

    Adera, Solomon; /Georgia Tech., Atlanta /SLAC

    2010-08-25T23:59:59.000Z

    A mechanical shutter which operates on demand is used to isolate a single pulse from a 120 Hz X-ray source. This is accomplished with a mechanical shutter which is triggered on demand with frequencies ranging from 0 to 10 Hz. The single pulse shutter is an iron blade that oscillates on a pivot in response to a force generated by a pair of pulsed electromagnets (current driven teeter-totter). To isolate an individual pulse from the X-ray beam, the motion of the mechanical shutter should be synchronized in such a way that it allows a single pulse to pass through the aperture and blocks the other incoming pulses. Two consecutive pulses are only {approx} 8 ms apart and the shutter is required to complete one full cycle such that no two pulses pass through the opening. Also the opening of the shutter blade needs to be at least 4 mm so that a 1 mm diameter rms Gaussian beam can pass through without modulation. However, the 4 mm opening is difficult to obtain due to blade rebound and oscillation of the blade after colliding with the electromagnet. The purpose of this project is to minimize and/or totally eliminate the rebound of the shutter blade in pursuit of maximizing the aperture while keeping the open window interval < {approx}12 ms.

  16. High reliability low jitter pulse generator

    DOE Patents [OSTI]

    Savage, Mark E.; Stoltzfus, Brian S.

    2013-01-01T23:59:59.000Z

    A method and concomitant apparatus for generating pulses comprising providing a laser light source, disposing a voltage electrode between ground electrodes, generating laser sparks using the laser light source via laser spark gaps between the voltage electrode and the ground electrodes, and outputting pulses via one or more insulated ground connectors connected to the voltage electrode.

  17. Heart Physiology Lab Part 1: Pulse Rate

    E-Print Network [OSTI]

    Loughry, Jim

    Heart Physiology Lab Part 1: Pulse Rate Measure your pulse in each of the following conditions (in in the class. You may use Table 1 in the Heart Physiology Worksheet for this, if you wish. Once you have all of the class averages for each measurement. You may use Graph 1 in the Heart Physiology Worksheet for this

  18. Infrared pulse characterization using four-wave mixing inside a few cycle pulse filament in air

    SciTech Connect (OSTI)

    Marceau, Claude, E-mail: claude.marceau.2@ulaval.ca; Thomas, Steven; Kassimi, Yacine; Gingras, Guillaume; Witzel, Bernd [Centre d'Optique, Photonique et Laser, Pavillon d'optique-photonique Québec (Québec), Université Laval, Québec G1V 0A6 (Canada)

    2014-02-03T23:59:59.000Z

    We demonstrate a four-wave mixing (FWM) technique to measure near- and mid-infrared (IR) laser pulse shapes in time domain. Few cycle 800?nm laser pulses were synchronized with the IR pulse and focused colinearly to generate a plasma filament in air. Second harmonic radiation around 400?nm was generated through FWM, with a yield proportional to the IR pulse intensity. Excellent signal to noise ratio was observed from 2.1??m to 18??m. With proper phase stabilization of the IR beam, this technique is a promising step toward direct electric field sensing of near-IR pulses in air.

  19. Ultrafast Pulse Shaping Approaches to Quantum Computing

    E-Print Network [OSTI]

    Debabrata Goswami

    2003-12-24T23:59:59.000Z

    Quantum computing exploits the quantum-mechanical nature of matter to exist in multiple possible states simultaneously. This new approach promises to revolutionize the present form of computing. As an approach to quantum computing, we discuss ultrafast laser pulse shaping, in particular, the acousto-optic modulator based Fourier-Transform pulse-shaper, which has the ability to modulate tunable high power ultrafast laser pulses. We show that optical pulse shaping is an attractive route to quantum computing since shaped pulses can be transmitted over optical hardware and the same infrastructure can be used for computation and optical information transfer. We also address the problem of extending coherence-times for optically induced processes.

  20. AN UPDATE ON NIF PULSED POWER

    SciTech Connect (OSTI)

    Arnold, P A; James, G F; Petersen, D E; Pendleton, D L; McHale, G B; Barbosa, F; Runtal, A S; Stratton, P L

    2009-06-22T23:59:59.000Z

    The National Ignition Facility (NIF) is a 192-beam laser fusion driver operating at Lawrence Livermore National Laboratory. NIF relies on three large-scale pulsed power systems to achieve its goals: the Power Conditioning Unit (PCU), which provides flashlamp excitation for the laser's injection system; the Power Conditioning System (PCS), which provides the multi-megajoule pulsed excitation required to drive flashlamps in the laser's optical amplifiers; and the Plasma Electrode Pockels Cell (PEPC), which enables NIF to take advantage of a fourpass main amplifier. Years of production, installation, and commissioning of the three NIF pulsed power systems are now complete. Seven-day-per-week operation of the laser has commenced, with the three pulsed power systems providing routine support of laser operations. We present the details of the status and operational experience associated with the three systems along with a projection of the future for NIF pulsed power.

  1. 140 GHz pulsed Fourier transform microwave spectrometer

    DOE Patents [OSTI]

    Kolbe, W.F.; Leskovar, B.

    1987-10-27T23:59:59.000Z

    A high frequency energy pulsing system suitable for use in a pulsed microwave spectrometer, including means for generating a high frequency carrier signal, and means for generating a low frequency modulating signal is disclosed. The carrier signal is continuously fed to a modulator and the modulating signal is fed through a pulse switch to the modulator. When the pulse switch is on, the modulator will produce sideband signals above and below the carrier signal frequency. A frequency-responsive device is tuned to one of the sideband signals and away from the carrier frequency so that the high frequency energization of the frequency-responsive device is controlled by the pulse switch. 5 figs.

  2. 140 GHz pulsed fourier transform microwave spectrometer

    DOE Patents [OSTI]

    Kolbe, William F. (Oakland, CA); Leskovar, Branko (Moraga, CA)

    1987-01-01T23:59:59.000Z

    A high frequency energy pulsing system suitable for use in a pulsed microwave spectrometer (10), including means (11, 19) for generating a high frequency carrier signal, and means (12) for generating a low frequency modulating signal. The carrier signal is continuously fed to a modulator (20) and the modulating signal is fed through a pulse switch (23) to the modulator. When the pulse switch (23) is on, the modulator (20) will produce sideband signals above and below the carrier signal frequency. A frequency-responsive device (31) is tuned to one of the sideband signals and away from the carrier frequency so that the high frequency energization of the frequency-responsive device (31) is controlled by the pulse switch (23).

  3. Femtosecond pulse shaping using plasmonic snowflake nanoantennas

    SciTech Connect (OSTI)

    Tok, Ruestue Umut; Sendur, Kuersat [Sabanci University, Orhanli-Tuzla, 34956, Istanbul (Turkey)

    2011-09-15T23:59:59.000Z

    We have theoretically demonstrated femtosecond pulse manipulation at the nanoscale using the plasmonic snowflake antenna's ability to localize light over a broad spectrum. To analyze the interaction of the incident femtosecond pulse with the plasmonic nanoantenna, we first decompose the diffraction limited incident femtosecond pulse into its spectral components. The interaction of each spectral component with the nanoantenna is analyzed using finite element technique. The time domain response of the plasmonic antenna is obtained using inverse Fourier transformation. It is shown that the rich spectral characteristics of the plasmonic snowflake nanoantenna allow manipulation of the femtosecond pulses over a wide spectrum. Light localization around the gap region of the nanoantenna is shown for femtosecond pulses. As the alignment of incident light polarization is varied, different antenna elements oscillate, which in turn creates a different spectrum and a distinct femtosecond response.

  4. Extension of harmonic cutoff in a multicycle chirped pulse combined with a chirp-free pulse

    SciTech Connect (OSTI)

    Xu Junjie; Zeng Bin; Yu Yongli [State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, P.O. Box 800-211, Shanghai 201800 (China)

    2010-11-15T23:59:59.000Z

    We demonstrate high-order harmonic generation in a wave form synthesized by a multicycle 800-nm chirped laser pulse and a chirp-free laser pulse. Compared with the case of using only a chirped pulse, both the harmonic cutoff and the extreme ultraviolet supercontinuum can be extended when a weak chirp-free pulse is combined with the chirped pulse. When chirp-free pulse intensity grows, the cutoff energy and bandwidth of the supercontinuum grow as well. It is found that the broad supercontinuum can be achieved for a driving pulse with long duration even though the driving pulse reaches 10 optical cycles. An isolated attosecond pulse with duration of about 59 as is obtained, and after appropriate phase compensation with a duration of about 11 as. In addition, by performing time-frequency analyses and the classical trajectory simulation, the difference in supercontinuum generation between the preceding wave form and a similar wave form synthesized by an 800-nm fundamental pulse and a 1600-nm subharmonic pulse is investigated.

  5. Ultrafast optical pulse shaping: A tutorial review Andrew M. Weiner

    E-Print Network [OSTI]

    Purdue University

    Ultrafast optical pulse shaping: A tutorial review Andrew M. Weiner Purdue University, School 2011 Keywords: Ultrafast optics Pulse shaping Femtosecond optics Coherent control Optical signal programmable reshapingof ultrafast pulses, or generation of arbitrary optical waveforms, according to user

  6. Information processing with longitudinal spectral decomposition of ultrashort pulses

    E-Print Network [OSTI]

    Saperstein, Robert Elliot

    2007-01-01T23:59:59.000Z

    decomposition of ultrafast pulses,” Appl. Opt. , doc. IDdecomposition of ultrafast pulses,” Appl. Opt. 47, A21-A31 (decomposition of ultrafast pulses,” Appl. Opt. 47, A21-A31 (

  7. The Homopolar Generator as a Pulsed Industrial Power Supply

    E-Print Network [OSTI]

    Weldon, J. M.; Weldon, W. F.

    1979-01-01T23:59:59.000Z

    power supply for numerous industrial applications such as large metal cross section pulsed resistance welding, pulsed billet heating for subsequent hot working processes, pulsed heating for localized forging processes, and magnetic metal forming. Each...

  8. The Homopolar Generator as a Pulsed Industrial Power Supply 

    E-Print Network [OSTI]

    Weldon, J. M.; Weldon, W. F.

    1979-01-01T23:59:59.000Z

    power supply for numerous industrial applications such as large metal cross section pulsed resistance welding, pulsed billet heating for subsequent hot working processes, pulsed heating for localized forging processes, and magnetic metal forming. Each...

  9. Reflection and Transmission of Pulsed Electromagnetic Fields through Multilayered

    E-Print Network [OSTI]

    Oughstun, Kurt

    Reflection and Transmission of Pulsed Electromagnetic Fields through Multilayered Biological Media- cally rigorous, physically correct description of the propagation of pulsed electromagnetic fields pulses through multilayered biological media consisting of three biological tissue layers rep- resenting

  10. Self-sustained picosecond pulse generation in a GaAlAs laser at an electrically tunable repetition rate by optoelectronic feedback

    SciTech Connect (OSTI)

    Lau, K.Y.; Yariv, A.

    1984-07-15T23:59:59.000Z

    We demonstrate that applying optoelectronic feedback to a high-speed, self-pulsing semiconductor laser is an effective and practical means of generating picosecond optical pulses (approx.10--20 ps) at a very high repetition rate, between 1 to 5 GHz, which can be electrically tuned. The optical pulses are very stable both on a short term basis with a frequency stability of one part in 10/sup 5/, and on the long term basis as a result of the absence of critical optical alignment. This laser system is potentially very useful in high-speed electro-optic signal processing, optical multiplexing, or laser ranging.

  11. The galactic double-mode Cepheids I. Frequency analysis of the light curves and comparison with single-mode Cepheids

    E-Print Network [OSTI]

    Ennio Poretti; Ilaria Pardo

    1996-12-05T23:59:59.000Z

    We submitted the available photometric V data of all the known galactic Double Mode Cepheids (DMCs) to a careful frequency analysis with the aim of detecting in each case the importance of the harmonics and of the cross coupling terms. For each object, starting from different data subsets, we progressively built a homogenous set of data, checking the consistency of the results step by step. It was demonstrated that each star displays a different content, showing that no a priori fit can be applied. Up to 4 harmonics were found for the fundamental radial mode (F); in every case, 2 harmonics were found for the first overtone radial mode (1 O). We also proceeded to a preliminar analysis of the Fourier parameters of the DMC light curves and we found a very close similarity between i) the light curves of the Classical Cepheids and those of the F-mode of the DMCs; ii) the light curves of the s-Cepheids and those of the 1 O-mode of the DMCs. The analysis of DMC light curves offers the possibility of unifying the light curves of Classical and s-Cepheids. The case of the unique DMC CO Aur is also discussed.

  12. Conversion from interchange-type modes to tearing modes: an explanation of tokamak anomalous transport

    E-Print Network [OSTI]

    Ito, Atsushi

    Conversion from interchange-type modes to tearing modes: an explanation of tokamak anomalous of non-classical tearing mode exists in tokamaks: viz., current interchange tearing modes (CITMs). CITMs type (e.g., interchange/ballooning modes, drift waves, etc.) due to resistivity gradient in tokamaks

  13. Estimation of temporal separation of slow light pulses in atomic vapors by weak measurement

    E-Print Network [OSTI]

    Pardeep Kumar; Shubhrangshu Dasgupta

    2015-03-16T23:59:59.000Z

    We show how two circular polarization components of a linearly polarized pulse, propagating through a coherently driven dilute atomic vapor, can be well resolved in time domain by weak measurement. Slower group velocity of one of the components due to electromagnetically induced transparency leads to a differential group delay between the two components. For low number density, this delay may not be large enough to temporally resolve the two components. We show how this can be enhanced in terms of mean time of arrival of the output pulse through a post-selected polarizer. We demonstrate the idea with all the analytical and numerical results, with a specific example of alkali atoms.

  14. Electromagnetically-induced transparency and light storing of a pair of pulses

    E-Print Network [OSTI]

    A. Raczynski; J. Zaremba; S. Zielinska-Kaniasty

    2003-07-30T23:59:59.000Z

    Electromagnetically-induced transparency and light storing are studied in the case of a medium of atoms in a double Lambda configuration, both in terms of dark- and bright-state polatitons and atomic susceptibility. It is proven that the medium can be made transparent simultaneously for two pulses following their self-adjusting so that a condition for an adiabatic evolution has become fulfilled. Analytic formulas are given for the shapes and phases of the transmitted/stored pulses. The level of transparency can be regulated by adjusting the heights and phases of the control fields.

  15. Progress towards sustainment of advanced tokamak modes in DIII-D

    SciTech Connect (OSTI)

    Rice, B.W. [Lawrence Livermore National Lab., CA (United States); Burrell, K.H.; Ferron, J.R. [General Atomics, San Diego, CA (United States)] [and others

    1998-12-01T23:59:59.000Z

    Improving confinement and beta limits simultaneously in long-pulse ELMy H-mode discharges is investigated. The product {beta}{sub N}H{sub 98y} serves as a useful figure-of-merit for performance, where {beta}{sub N} {triple_bond} {beta}/(I/aB) and H{sub 98y} is the ratio of the thermal confinement time relative to the most recent ELMy H-mode confinement scaling established by the ITER confinement database working group. In discharges with q{sub 0} {approximately} 1 (no sawteeth) and discharges with q{sub min} > 1.5 and negative central magnetic shear, {beta}{sub N} {approximately} 2.9 and H{sub 98y} {approximately} 1.4 are sustained for up to 2 s. Although peaked profiles are observed, steep internal transport barriers are not present. Further increases in {beta}{sub N} in these discharges is limited by neoclassical tearing modes (NTM) in the positive shear region. In another recently developed regime, {beta}{sub N} {approximately} 3.8 and H{sub 98y} {approximately} 1.8 has been sustained during large infrequent ELMs in non-sawtoothing discharges with 1{sub 0} {approximately} 1. This level of performance is similar to that obtained in ELM-free regimes such as VH-mode. The limitation on {beta}{sub N} and pulse length in these discharges is also the onset of NTMs.

  16. Pulsed Photonuclear Assessment (PPA) Technology Enhancement Study

    SciTech Connect (OSTI)

    Not Available

    2006-04-01T23:59:59.000Z

    The Idaho National Laboratory (INL) along with the Los Alamos National Laboratory (LANL) and Idaho State University’s Idaho Accelerator Center (IAC) has designed and tested a nominal 10-MeV prototype Pulsed Photonuclear Assessment (PPA) inspection system to detect shielded nuclear material. This report highlights two specific areas that will provide further PPA technology enhancements, namely, an optimal gamma-ray detection system and the off axis radiation detection sensitivity. Detection of low-atomic number (Z) shielded nuclear material had been initially addressed by the inclusion of dedicated Geiger-Müller (GM) detectors co-located above each of the Photonuclear Neutron Detectors (PNDs). Several different radiation detectors were investigated to assess if this type of gamma-ray detector was optimal. The LND 719 GM detector was shown to have the best photon sensitivity and demonstrated an optimal ability to detect low-Z shielded nuclear material. Beyond the technical performance of this detector, its low cost and availability makes it a logical choice for a field-deployable system. In terms of off-axis detection sensitivity, simulation and benchmarking experiments have indicated that the PPA inspection system can successfully detect nuclear material (within 120 seconds) in various shielding configurations even when it is located at a distance of as much as 30 cm off the interrogating beam axis (the exact sensitivity to off-axis interrogations will be largely dependent on the actual shielding material). As a general rule, high-Z shielding will allow detection at larger off-axis distances than low-Z materials.

  17. analog pulse shape: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    systems. Digital pulse shaping Krishnapura, Nagendra 2 Dynamic Matter-Wave Pulse Shaping Quantum Physics (arXiv) Summary: In this paper we discuss possibilities...

  18. A Combined Vacuum Ultraviolet Laser and Synchrotron Pulsed Field...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Vacuum Ultraviolet Laser and Synchrotron Pulsed Field Ionization Study of BCl. A Combined Vacuum Ultraviolet Laser and Synchrotron Pulsed Field Ionization Study of BCl. Abstract:...

  19. Spiraling Laser Pulses Could Change Nature of Graphene

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Spiraling Laser Pulses Could Change Nature of Graphene Spiraling Laser Pulses Could Change Nature of Graphene Simulations Run at NERSC Show It Could Transform from Metal to...

  20. Damage from pulses with arbitrary temporal shapes

    SciTech Connect (OSTI)

    Trenholme, J.B.

    1994-06-06T23:59:59.000Z

    In fusion laser designs, the laser pulse has a complicated temporal shape which undergoes significant change as it passes through the laser. Our damage data, however, was taken with pulses whose temporal shapes were (more or less) Gaussian. We want to determine the damage propensity of a material exposed to a pulse of arbitrary temporal shape , given data taken with Gaussian pulses of different pulse widths. To do so, we must adopt a physical model of damage. This model will contain some number of parameters that depend on material properties, geometry, and so forth. We determine the parameters of the model appropriate to each material by fitting the model to the Gaussian data for that material. The resulting normalized model is then applied, using the appropriate pulse shape, to find the damage level for a specific material subjected to a specific pulse. The model we shall assume is related to diffusion, although (as we shall see) the experimental results do not fit any simple diffusion model. Initially, we will discuss simple diffusion models. We then examine some experimental data, and then develop a modified diffusive model from that data. That modified model is then used to predict damage levels in various portions of the NIF laser design.

  1. Rapidly pulsed TRIGA reactor: an intense source for neutron scattering experiments

    SciTech Connect (OSTI)

    Whittemore, William L. [General Atomics, San Diego, CA (United States)

    1994-07-01T23:59:59.000Z

    The need for ever increasing intensities of thermal neutron beams for neutron scattering experiments has stimulated the development of intense steady state research reactors such as the 53-MW ILL reactor at Grenoble. The source flux at the reactor end of the beam ports is typically 10{sup 15}n/cm{sup 2}.s for its thermal neutron beams. To achieve still higher source fluxes of neutrons, the family of pulsing IBR was developed. In this type of facility the pulse repetition rate is low ({approx}5/sec) typically but the instantaneous peak fluxes are high, ranging up to 5 x 10{sup 15}n/cm{sup 2}.s at the surface of the moderator. Another type of intense neutron source is that exemplified by the proton synchrotron accelerators with their spallation targets. The first of these has been the IPNS at Argonne National laboratory. This neutron source produces 30 pulses per second with an individual peak thermal neutron intensity of 4 x 10{sup 14}n/cm{sup 2}.s from the moderator. An equivalent, alternative intense neutron source can be based on a rapidly pulsed TRIGA reactor. With a pulsed thermal neutron intensity of more than 10{sup 15}n/cm{sup 2}.s occurring 50 times per second at the source end of beam ports, the rapidly pulsed TRIGA reactor combines some of the best features of the pulsed fast reactors such as IBR-2 and the spallation neutron sources but with the safety of a thermal neutron reactor with a large, prompt, negative temperature coefficient of reactivity. The initial concept of the rapidly pulsed TRIGA reactor was developed and initially reported in 1966. Subsequently, the standard fuel format for U-ZrH{sub x} fuel has been developed to include a small diameter fuel particularly well suited for the rapidly pulsed application. This fuel is LEU, satisfying all the requirements for non proliferation, and has a very long core life time. In the proposed application, the peak fuel temperature does not vary more than 1 deg. C from the average peak fuel temperatures during each pulse. Hence long term metallurgical stability is thus assured. With a core lifetime that can be designed for up to 10,000 MWD, operation at an average power of 10 MW (with peak pulsed powers of {approx}50 MW) with an equilibrium core can be conducted for 1000 full power days. (author)

  2. Longitudinal mode spectrum of semiconductor lasers under high-speed modulation

    SciTech Connect (OSTI)

    Lau, K.Y.; Harder, C.; Yariv, A.

    1984-01-01T23:59:59.000Z

    Experimental observations of the lasing spectrum of a single-mode semiconductor laser under continuous microwave modulation reveal that the lasing spectrum is apparently locked to a single-longitudinal mode for optical modulation depths up to about 80 percent, beyond which the lasing spectrum breaks into multimode oscillation. The width of the envelope of the multimode spectrum increases very rapidly with further increase in modulation depth. These results are satisfactorily explained by a theoretical treatment which gives simple analytic results for the time evolution of the individual longitudinal modes. It also yields considerable insight into spectral dynamics, and enables one to predict the dynamic lasing spectrum of a laser from its CW lasing spectra at various output powers. The results can also be used to predict the amount of spectral envelope broadening under single or pseudorandom pulse modulation.

  3. Preference Term List

    E-Print Network [OSTI]

    Wu, Yih-Min

    · Subject Bibliography Library #12; 1/2 · Edit Preferences #12; 2/2 · Library ­ PreferencesDisplay Fields · ­ PreferencesDuplicates · ­ PreferencesFind Full Text · PreferencesReference Types #12;? #12;Journal term list() · Bibliography() · Footnotes() · #12;15 4.Journal Article "Insert Field" #12;16 5. : "Reference Types ""Insert

  4. System for generating shaped optical pulses and measuring optical pulses using spectral beam deflection (SBD)

    DOE Patents [OSTI]

    Skupsky, S.; Kessler, T.J.; Letzring, S.A.

    1993-11-16T23:59:59.000Z

    A temporally shaped or modified optical output pulse is generated from a bandwidth-encoded optical input pulse in a system in which the input pulse is in the form of a beam which is spectrally spread into components contained within the bandwidth, followed by deflection of the spectrally spread beam (SBD) thereby spatially mapping the components in correspondence with the temporal input pulse profile in the focal plane of a lens, and by spatially selective attenuation of selected components in that focal plane. The shaped or modified optical output pulse is then reconstructed from the attenuated spectral components. The pulse-shaping system is particularly useful for generating optical pulses of selected temporal shape over a wide range of pulse duration, such pulses finding application in the fields of optical communication, optical recording and data storage, atomic and molecular spectroscopy and laser fusion. An optical streak camera is also provided which uses SBD to display the beam intensity in the focal plane as a function of time during the input pulse. 10 figures.

  5. System for generating shaped optical pulses and measuring optical pulses using spectral beam deflection (SBD)

    DOE Patents [OSTI]

    Skupsky, Stanley (Rochester, NY); Kessler, Terrance J. (Rochester, NY); Letzring, Samuel A. (Honeoye Falls, NY)

    1993-01-01T23:59:59.000Z

    A temporally shaped or modified optical output pulse is generated from a bandwidth-encoded optical input pulse in a system in which the input pulse is in the form of a beam which is spectrally spread into components contained within the bandwidth, followed by deflection of the spectrally spread beam (SBD) thereby spatially mapping the components in correspondence with the temporal input pulse profile in the focal plane of a lens, and by spatially selective attenuation of selected components in that focal plane. The shaped or modified optical output pulse is then reconstructed from the attenuated spectral components. The pulse-shaping system is particularly useful for generating optical pulses of selected temporal shape over a wide range of pulse duration, such pulses finding application in the fields of optical communication, optical recording and data storage, atomic and molecular spectroscopy and laser fusion. An optical streak camera is also provided which uses SBD to display the beam intensity in the focal plane as a function of time during the input pulse.

  6. Nox reduction system utilizing pulsed hydrocarbon injection

    DOE Patents [OSTI]

    Brusasco, Raymond M. (Livermore, CA); Penetrante, Bernardino M. (San Ramon, CA); Vogtlin, George E. (Fremont, CA); Merritt, Bernard T. (Livermore, CA)

    2001-01-01T23:59:59.000Z

    Hydrocarbon co-reductants, such as diesel fuel, are added by pulsed injection to internal combustion engine exhaust to reduce exhaust NO.sub.x to N.sub.2 in the presence of a catalyst. Exhaust NO.sub.x reduction of at least 50% in the emissions is achieved with the addition of less than 5% fuel as a source of the hydrocarbon co-reductants. By means of pulsing the hydrocarbon flow, the amount of pulsed hydrocarbon vapor (itself a pollutant) can be minimized relative to the amount of NO.sub.x species removed.

  7. Apparatus and method for optical pulse measurement

    DOE Patents [OSTI]

    Trebino, Rick P. (Livermore, CA); Tsang, Thomas (Brooklyn, NY); Fittinghoff, David N. (San Diego, CA); Sweetser, John N. (Livermore, CA); Krumbuegel, Marco A. (Danville, CA)

    1999-12-28T23:59:59.000Z

    Practical third-order frequency-resolved optical grating (FROG) techniques for characterization of ultrashort optical pulses are disclosed. The techniques are particularly suited to the measurement of single and/or weak optical pulses having pulse durations in the picosecond and subpicosecond regime. The relative quantum inefficiency of third-order nonlinear optical effects is compensated for through i) use of phase-matched transient grating beam geometry to maximize interaction length, and ii) use of interface-enhanced third-harmonic generation.

  8. Means and method for characterizing high power, ultra short laser pulses in a real time, on line manner

    DOE Patents [OSTI]

    Veligdan, J.T.

    1994-03-08T23:59:59.000Z

    An ultra short (<10 ps), high power laser pulse is temporally characterized by a system that uses a physical measurement of a wavefront that has been altered in a known manner. The system includes a first reflection switch to remove a portion of a pulse from a beam of pulses, then includes a second reflection switch, operating in a mode that is opposite to the first reflection switch, to slice off a portion of that removed portion. The sliced portion is then directed to a measuring device for physical measurement. The two reflection switches are arranged with respect to each other and with respect to the beam of ultra short pulses such that physical measurement of the sliced portion is related to the temporal measurement of the ultra short pulse by a geometric or trigonometric relationship. The reflection switches are operated by a control pulse that is directed to impinge on each of the reflection switches at a 90[degree] angle of incidence. 8 figures.

  9. Real-time multi-mode neutron multiplicity counter

    DOE Patents [OSTI]

    Rowland, Mark S; Alvarez, Raymond A

    2013-02-26T23:59:59.000Z

    Embodiments are directed to a digital data acquisition method that collects data regarding nuclear fission at high rates and performs real-time preprocessing of large volumes of data into directly useable forms for use in a system that performs non-destructive assaying of nuclear material and assemblies for mass and multiplication of special nuclear material (SNM). Pulses from a multi-detector array are fed in parallel to individual inputs that are tied to individual bits in a digital word. Data is collected by loading a word at the individual bit level in parallel, to reduce the latency associated with current shift-register systems. The word is read at regular intervals, all bits simultaneously, with no manipulation. The word is passed to a number of storage locations for subsequent processing, thereby removing the front-end problem of pulse pileup. The word is used simultaneously in several internal processing schemes that assemble the data in a number of more directly useable forms. The detector includes a multi-mode counter that executes a number of different count algorithms in parallel to determine different attributes of the count data.

  10. Quantum simulation of Dirac fermion mode, Majorana fermion mode and Majorana-Weyl fermion mode in cavity QED lattice

    E-Print Network [OSTI]

    Sujit Sarkar

    2014-09-11T23:59:59.000Z

    Quantum simulation aims to simulate a quantum system using a controble laboratory system that underline the same mathematical model. Cavity QED lattice system is that prescribe system to simulate the relativistic quantum effect. We quantum simulate the Dirac fermion mode, Majorana fermion mode and Majorana-Weyl fermion mode and a crossover between them in cavity QED lattice. We also present the different analytical relations between the field operators for different mode excitations.

  11. Continuous scanning mode for ptychography

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Clark, Jesse N.; Huang, Xiaojing; Harder, Ross J.; Robinson, Ian K.

    2014-01-01T23:59:59.000Z

    We outline how ptychographic imaging can be performed without the need for discrete scan positions. Through an idealized experiment, we demonstrate how a discrete-position scan regime can be replaced with a continuously scanned one with suitable modification of the reconstruction scheme based on coherent modes. The impact of this is that acquisition times can be reduced, significantly aiding ptychographic imaging with x rays, electrons, or visible light.

  12. Transition between Two Oscillation Modes

    E-Print Network [OSTI]

    Ricardo Lopez-Ruiz; Yves Pomeau

    2002-05-17T23:59:59.000Z

    A model for the symmetric coupling of two self-oscillators is presented. The nonlinearities cause the system to vibrate in two modes of different symmetries. The transition between these two regimes of oscillation can occur by two different scenarios. This might model the release of vortices behind circular cylinders with a possible transition from a symmetric to an antisymmetric Benard-von Karman vortex street.

  13. Torsional Oscillations of Relativistic Stars with Dipole Magnetic Fields II. Global Alfvén Modes

    E-Print Network [OSTI]

    H. Sotani; K. D. Kokkotas; N. Stergioulas; M. Vavoulidis

    2006-11-21T23:59:59.000Z

    We investigate torsional Alfv\\'{e}n modes of relativistic stars with a global dipole magnetic field. It has been noted recently (Glampedakis et al. 2006) that such oscillation modes could serve as as an alternative explanation (in contrast to torsional crustal modes) for the SGR phenomenon, if the magnetic field is not confined to the crust. We compute global Alfv\\'{e}n modes for a representative sample of equations of state and magnetar masses, in the ideal MHD approximation and ignoring $\\ell \\pm 2$ terms in the eigenfunction. We find that the presence of a realistic crust has a negligible effect on Alfv\\'{e}n modes for $B > 4\\times 10^{15}$ G. Furthermore, we find strong avoided crossings between torsional Alfv\\'{e}n modes and torsional crust modes. For magnetar-like magnetic field strengths, the spacing between consecutive Alfv\\'{e}n modes is of the same order as the gap of avoided crossings. As a result, it is not possible to identify modes of predominantly crustal character and all oscillations are predominantly Alfv\\'{e}n-like. Interestingly, we find excellent agreement between our computed frequencies and observed frequencies in two SGRs, for a maximum magnetic field strenght in the range of (0.8--1.2)$\\times 10^{16}$ G.

  14. Detection of Tones and Pulses using a Large, Uncalibrated Array S.W. Ellingson

    E-Print Network [OSTI]

    Ellingson, Steven W.

    ]; and wide- band pulses associated with (for example) gamma ray bursts [2] and intermittent "giant pulses

  15. Crop Insurance Terms and Definitions

    E-Print Network [OSTI]

    Stokes, Kenneth; Waller, Mark L.; Outlaw, Joe; Barnaby, G. A. Art

    2008-10-17T23:59:59.000Z

    This publication is a glossary of terms used by the crop insurance industry. There are definitions for terms used in crop insurance documents and for terms pertaining to coverage levels, farming, reports, units and parties to contracts....

  16. Ultrafast Optical Pulses: Synthesis and Applications

    E-Print Network [OSTI]

    Wang, Kai

    2013-12-11T23:59:59.000Z

    This dissertation is devoted to ultrafast waveform synthesis using coherent Raman sidebands with the assistance of pulse shapers based on acousto-optic programmable dispersive ?lter (AOPDF) or deformable mirror (DM). Ultrashort optical science has...

  17. Pulse Pressure Forming of Lightweight Materials, Development...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Merit Review and Peer Evaluation Meeting, June 7-11, 2010 -- Washington D.C. lm015smith2010o.pdf More Documents & Publications Pulse-Pressure Forming of Lightweight Metals...

  18. Ultrasonic unipolar pulse/echo instrument

    DOE Patents [OSTI]

    Hughes, M.J.; Hsu, D.K.; Thompson, D.O.; Wormley, S.J.

    1993-04-06T23:59:59.000Z

    An ultrasonic unipolar pulse/echo instrument uses active switches and a timing and drive circuitry to control electrical energy to a transducer, the discharging of the transducer, and the opening of an electrical pathway to the receiving circuitry for the returning echoes. The active switches utilize MOSFET devices along with decoupling circuitry to insure the preservation of the unipolar nature of the pulses, insure fast transition times, and maintain broad band width and time resolution. A housing contains the various circuitry and switches and allows connection to a power supply and a movable ultrasonic transducer. The circuitry maintains low impedance input to the transducer during transmitting cycles, and high impedance between the transducer and the receiving circuit during receive cycles to maintain the unipolar pulse shape. A unipolar pulse is valuable for nondestructive evaluation, a prime use for the present instrument.

  19. Optically controlled delays for broadband pulses

    E-Print Network [OSTI]

    Sun, Q. Q.; Rostovtsev, Y. V.; Dowling, J. P.; Scully, Marlan O.; Zubairy, M. Suhail

    2005-01-01T23:59:59.000Z

    We propose a scheme that provides large controllable delays for broadband optical pulses. The system is based on the steep dispersion of a coherently driven medium, in which the narrow electromagnetically induced transparency (EIT) band is overcome...

  20. Optimal arbitrarily accurate composite pulse sequences

    E-Print Network [OSTI]

    Low, Guang Hao

    Implementing a single-qubit unitary is often hampered by imperfect control. Systematic amplitude errors ?, caused by incorrect duration or strength of a pulse, are an especially common problem. But a sequence of imperfect ...

  1. Post pulse shutter for laser amplifier

    DOE Patents [OSTI]

    Bradley, Laird P. [Livermore, CA; Carder, Bruce M. [Antioch, CA; Gagnon, William L. [Berkeley, CA

    1981-03-17T23:59:59.000Z

    Apparatus and method for quickly closing off the return path for an amplified laser pulse at the output of an amplifier so as to prevent damage to amplifiers and other optical components appearing earlier in the chain by the return of an amplified pulse. The apparatus consists of a fast retropulse or post pulse shutter to suppress target reflection and/or beam return. This is accomplished by either quickly placing a solid across the light transmitting aperture of a component in the chain, such as a spatial filter pinhole, or generating and directing a plasma with sufficiently high density across the aperture, so as to, in effect, close the aperture to the returning amplified energy pulse.

  2. Post pulse shutter for laser amplifier

    DOE Patents [OSTI]

    Bradley, L.P.; Carder, B.M.; Gagnon, W.L.

    1981-03-17T23:59:59.000Z

    Disclosed are an apparatus and method for quickly closing off the return path for an amplified laser pulse at the output of an amplifier so as to prevent damage to amplifiers and other optical components appearing earlier in the chain by the return of an amplified pulse. The apparatus consists of a fast retropulse or post pulse shutter to suppress target reflection and/or beam return. This is accomplished by either quickly placing a solid across the light transmitting aperture of a component in the chain, such as a spatial filter pinhole, or generating and directing a plasma with sufficiently high density across the aperture, so as to, in effect, close the aperture to the returning amplified energy pulse. 13 figs.

  3. LANL: AOT & LANSCE The Pulse February 2010

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    supported lipid bilayer (Image for October in APS 2010 calendar). continued on page 4 The Pulse-Newsletter of the Los Alamos Neutron Science Center and Accelerator Operations and...

  4. An investigation of the dynamic separation of spot welds under plane tensile pulses

    SciTech Connect (OSTI)

    Ma, Bohan; Fan, Chunlei; Chen, Danian, E-mail: chdnch@nbu.edu.cn; Wang, Huanran; Zhou, Fenghua [Mechanics and Materials Science Research Center, Ningbo University, Zhejiang 315211 (China)

    2014-08-07T23:59:59.000Z

    We performed ultra-high-speed tests for purely opening spot welds using plane tensile pulses. A gun system generated a parallel impact of a projectile plate onto a welded plate. Induced by the interactions of the release waves, the welded plate opened purely under the plane tensile pulses. We used the laser velocity interferometer system for any reflector to measure the velocity histories of the free surfaces of the free part and the spot weld of the welded plate. We then used a scanning electron microscope to investigate the recovered welded plates. We found that the interfacial failure mode was mainly a brittle fracture and the cracks propagated through the spot nugget, while the partial interfacial failure mode was a mixed fracture comprised ductile fracture and brittle fracture. We used the measured velocity histories to evaluate the tension stresses in the free part and the spot weld of the welded plate by applying the characteristic theory. We also discussed the different constitutive behaviors of the metals under plane shock loading and under uniaxial split Hopkinson pressure bar tests. We then compared the numerically simulated velocity histories of the free surfaces of the free part and the spot weld of the welded plate with the measured results. The numerical simulations made use of the fracture stress criteria, and then the computed fracture modes of the tests were compared with the recovered results.

  5. Assessment and Mitigation of Electromagnetic Pulse (EMP) Impacts at Short-pulse Laser Facilities

    SciTech Connect (OSTI)

    Brown, Jr., C G; Bond, E; Clancy, T; Dangi, S; Eder, D C; Ferguson, W; Kimbrough, J; Throop, A

    2010-02-04T23:59:59.000Z

    The National Ignition Facility (NIF) will be impacted by electromagnetic pulse (EMP) during normal long-pulse operation, but the largest impacts are expected during short-pulse operation utilizing the Advanced Radiographic Capability (ARC). Without mitigation these impacts could range from data corruption to hardware damage. We describe our EMP measurement systems on Titan and NIF and present some preliminary results and thoughts on mitigation.

  6. Semianalytic model of electron pulse propagation: Magnetic lenses and rf pulse compression cavities

    SciTech Connect (OSTI)

    Berger, Joel A.; Schroeder, W. Andreas [Department of Physics, University of Illinois at Chicago, 845 W. Taylor (M/C 273), Chicago, Illinois 60607 (United States)

    2010-12-15T23:59:59.000Z

    The analytical Gaussian electron pulse propagation model of Michalik and Sipe [J. Appl. Phys. 99, 054908 (2006)] is extended to include the action of external forces on the pulse. The resultant ability to simulate efficiently the effect of electron optical elements (e.g., magnetic lenses and radio-frequency cavities) allows for the rapid assessment of electron pulse delivery systems in time-resolved ultrafast electron diffraction and microscopy experiments.

  7. Assessment and Mitigation of Electromagnetic Pulse (EMP) Impacts at Short-pulse Laser Facilities

    SciTech Connect (OSTI)

    Brown, Jr., C G; Bond, E; Clancy, T; Dangi, S; Eder, D C; Ferguson, W; Kimbrough, J; Throop, A

    2009-10-02T23:59:59.000Z

    The National Ignition Facility (NIF) will be impacted by electromagnetic pulse (EMP) during normal long-pulse operation, but the largest impacts are expected during short-pulse operation utilizing the Advanced Radiographic Capability (ARC). Without mitigation these impacts could range from data corruption to hardware damage. We describe our EMP measurement systems on Titan and NIF and present some preliminary results and thoughts on mitigation.

  8. Optical waveguides having flattened high order modes

    DOE Patents [OSTI]

    Messerly, Michael Joseph; Beach, Raymond John; Heebner, John Edward; Dawson, Jay Walter; Pax, Paul Henry

    2014-08-05T23:59:59.000Z

    A deterministic methodology is provided for designing optical fibers that support field-flattened, ring-like higher order modes. The effective and group indices of its modes can be tuned by adjusting the widths of the guide's field-flattened layers or the average index of certain groups of layers. The approach outlined here provides a path to designing fibers that simultaneously have large mode areas and large separations between the propagation constants of its modes.

  9. A versatile femtosecond stimulated Raman spectroscopy setup with tunable pulses in the visible to near infrared

    SciTech Connect (OSTI)

    Zhu, Liangdong [Department of Physics, Oregon State University, Corvallis, Oregon 97331 (United States); Liu, Weimin [Department of Chemistry, Oregon State University, Corvallis, Oregon 97331 (United States); Fang, Chong, E-mail: Chong.Fang@oregonstate.edu [Department of Physics, Oregon State University, Corvallis, Oregon 97331 (United States); Department of Chemistry, Oregon State University, Corvallis, Oregon 97331 (United States)

    2014-07-28T23:59:59.000Z

    We demonstrate a versatile and efficient setup to perform femtosecond stimulated Raman spectroscopy (FSRS). Technical innovations are implemented to achieve the wavelength tunability for both the picosecond narrowband Raman pump pulse and femtosecond broadband Raman probe pulse. Using a simplified one-grating scheme in a home-built second harmonic bandwidth compressor followed by a two-stage noncollinear optical parametric amplifier, we tune the Raman pump pulse from ca. 480 to 750?nm. To generate the suitable Raman probe pulse in tandem, we rely on our recently demonstrated broadband up-converted multicolor array technique that readily provides tunable broadband laser sidebands across the visible to near-infrared range. This unique setup has unparalleled flexibility for conducting FSRS. We measure the ground-state Raman spectra of a cyclohexane standard using tunable pump-probe pairs at various wavelengths across the visible region. The best spectral resolution is ?12?cm{sup ?1}. By tuning the pump wavelength closer to the electronic absorption band of a photoacid pyranine in water, we observe the pre-resonantly enhanced Raman signal. The stimulated Raman gain of the 1627?cm{sup ?1} mode is increased by over 15 times.

  10. Pulsed, Photonuclear-induced, Neutron Measurements of Nuclear Materials with Composite Shielding

    SciTech Connect (OSTI)

    James Jones; Kevin Haskell; Rich Waston; William Geist; Jonathan Thron; Corey Freeman; Martyn Swinhoe; Seth McConchie; Eric Sword; Lee Montierth; John Zabriskie

    2011-07-01T23:59:59.000Z

    Active measurements were performed using a 10-MeV electron accelerator with inspection objects containing various nuclear and nonnuclear materials available at the Idaho National Laboratory’s Zero Power Physics Reactor (ZPPR) facility. The inspection objects were assembled from ZPPR reactor plate materials to evaluate the measurement technologies for the characterization of plutonium, depleted uranium or highly enriched uranium shielded by both nuclear and non-nuclear materials. A series of pulsed photonuclear, time-correlated measurements were performed with unshielded calibration materials and then compared with the more complex composite shield configurations. The measurements used multiple 3He detectors that are designed to detect fission neutrons between pulses of an electron linear accelerator. The accelerator produced 10-MeV bremsstrahlung X-rays at a repetition rate of 125 Hz (8 ms between pulses) with a 4-us pulse width. All inspected objects were positioned on beam centerline and 100 cm from the X-ray source. The time-correlated data was collected in parallel using both a Los Alamos National Laboratory-designed list-mode acquisition system and a commercial multichannel scaler analyzer. A combination of different measurement configurations and data analysis methods enabled the identification of each object. This paper describes the experimental configuration, the ZPPR inspection objects used, and the various measurement and analysis results for each inspected object.

  11. Modeling pulse profiles of accreting millisecond pulsars

    E-Print Network [OSTI]

    Juri Poutanen

    2008-09-14T23:59:59.000Z

    I review the basic observational properties of accreting millisecond pulsars that are important for understanding the physics involved in formation of their pulse profiles. I then discuss main effects responsible for shaping these profiles. Some analytical results that help to understand the results of simulations are presented. Constraints on the pulsar geometry and the neutron star equation of state obtained from the analysis of the pulse profiles are discussed.

  12. Electromagnetic or other directed energy pulse launcher

    DOE Patents [OSTI]

    Ziolkowski, Richard W. (Livermore, CA)

    1990-01-01T23:59:59.000Z

    The physical realization of new solutions of wave propagation equations, such as Maxwell's equations and the scaler wave equation, produces localized pulses of wave energy such as electromagnetic or acoustic energy which propagate over long distances without divergence. The pulses are produced by driving each element of an array of radiating sources with a particular drive function so that the resultant localized packet of energy closely approximates the exact solutions and behaves the same.

  13. Multiple laser pulse ignition method and apparatus

    DOE Patents [OSTI]

    Early, James W. (Los Alamos, NM)

    1998-01-01T23:59:59.000Z

    Two or more laser light pulses with certain differing temporal lengths and peak pulse powers can be employed sequentially to regulate the rate and duration of laser energy delivery to fuel mixtures, thereby improving fuel ignition performance over a wide range of fuel parameters such as fuel/oxidizer ratios, fuel droplet size, number density and velocity within a fuel aerosol, and initial fuel temperatures.

  14. Generation of unipolar pulses from nonunipolar optical pulses in a nonlinear medium

    SciTech Connect (OSTI)

    Kozlov, Victor V. [Department of Information Engineering, Universita degli Studi di Brescia, Via Branze 38, I-25123 Brescia (Italy); Department of Physics, St. Petersburg State University, Petrodvoretz, St. Petersburg, 198504 (Russian Federation); Rosanov, Nikolay N. [Institute of Laser Physics, Vavilov State Optical Institute, Birzhevaya liniya, 12, St. Petersburg, 199034 (Russian Federation); St. Petersburg State University of Information Technologies, Mechanics and Optics, St. Petersburg, 197101 (Russian Federation); De Angelis, Costantino; Wabnitz, Stefan [Department of Information Engineering, Universita degli Studi di Brescia, Via Branze 38, I-25123 Brescia (Italy)

    2011-08-15T23:59:59.000Z

    A unipolar electromagnetic pulse is a pulse with nonzero value of the static component of the Fourier spectrum of its real electric field (and not its envelope). We show how to efficiently generate unipolar pulses through propagation of an initially nonunipolar pulse in a nonlinear optical medium. One of the major results is the demonstration that the static component can only be generated in equal portions between the forward- and backward-traveling waves in the presence of nonlinear backscattering in a nonlinear medium.

  15. Dissociative ionization of H{sub 2} in an attosecond pulse train and delayed laser pulse

    SciTech Connect (OSTI)

    He Feng; Thumm, Uwe [James R. Macdonald Laboratory, Kansas State University, Manhattan, Kansas 66506-2604 (United States)

    2010-05-15T23:59:59.000Z

    The ionization of H{sub 2} in a single attosecond extreme ultraviolet (XUV) pulse generates a nuclear wave packet in H{sub 2}{sup +}, which is entangled with the emitted photoelectron wave packet. The nuclear wave-packet dynamics can be observed by dissociating H{sub 2}{sup +} in a delayed IR laser pulse. If H{sub 2} is ionized by a sequence of XUV pulses of an attosecond pulse train, whether or not the corresponding sequence of nuclear wave packets in H{sub 2}{sup +} is detected as a coherent or incoherent superposition depends on whether and how the photoelectrons are observed. We simulate the nuclear dynamics in this XUV-pump-IR-probe scenario and analyze our numerical results for both single attosecond pump pulses and pump-pulse trains of different lengths and temporal spacings between individual XUV pulses. By superimposing nuclear wave packets in H{sub 2}{sup +} generated by individual pulses in the pump-pulse train incoherently, we calculate proton kinetic energy release spectra that are in good qualitative agreement with the recent experiment of Kelkensberg et al. [Phys. Rev. Lett. 103, 123005 (2009)].

  16. Broadband frequency mode entanglement in waveguided PDC

    E-Print Network [OSTI]

    Andreas Eckstein; Christine Silberhorn

    2008-07-04T23:59:59.000Z

    We report the observation of beatings of the coincidence event rate in a Hong-Ou-Mandel interference (HOMI) between signal and idler photons from a parametric downconversion (PDC) process inside a multi-mode KTP waveguide. As explanation we introduce bi-photonic states entangled in their broadband frequency modes generated by waveguide mode triples and propose a suitable entanglement detection scheme.

  17. Hydrodynamic Lyapunov Modes in Translation Invariant Systems

    E-Print Network [OSTI]

    Hydrodynamic Lyapunov Modes in Translation Invariant Systems Jean­Pierre Eckmann and Omri Gat De modes in the slowly growing part of the Lyapunov spectrum, which are analogous to the hydrodynamic modes)]. The hydrodynamic Lyapunov vectors loose the typical random structure and exhibit instead the structure of weakly

  18. Hydrodynamic Lyapunov Modes in Translation Invariant Systems

    E-Print Network [OSTI]

    Eckmann, Jean-Pierre

    Hydrodynamic Lyapunov Modes in Translation Invariant Systems Jean­Pierre Eckmann and Omri Gat De modes in the slowly growing part of the Lyapunov spectrum, which are analogous to the hydrodynamic modes)]. The hydrodynamic Lyapunov vectors loose the typical random structure and exhibit instead the structure of weakly

  19. Tunable pulsed narrow bandwidth light source

    DOE Patents [OSTI]

    Powers, Peter E. (Dayton, OH); Kulp, Thomas J. (Livermore, CA)

    2002-01-01T23:59:59.000Z

    A tunable pulsed narrow bandwidth light source and a method of operating a light source are provided. The light source includes a pump laser, first and second non-linear optical crystals, a tunable filter, and light pulse directing optics. The method includes the steps of operating the pump laser to generate a pulsed pump beam characterized by a nanosecond pulse duration and arranging the light pulse directing optics so as to (i) split the pulsed pump beam into primary and secondary pump beams; (ii) direct the primary pump beam through an input face of the first non-linear optical crystal such that a primary output beam exits from an output face of the first non-linear optical crystal; (iii) direct the primary output beam through the tunable filter to generate a sculpted seed beam; and direct the sculpted seed beam and the secondary pump beam through an input face of the second non-linear optical crystal such that a secondary output beam characterized by at least one spectral bandwidth on the order of about 0.1 cm.sup.-1 and below exits from an output face of the second non-linear optical crystal.

  20. Pulse width modulation inverter with battery charger

    DOE Patents [OSTI]

    Slicker, James M. (Union Lake, MI)

    1985-01-01T23:59:59.000Z

    An inverter is connected between a source of DC power and a three-phase AC induction motor, and a microprocessor-based circuit controls the inverter using pulse width modulation techniques. In the disclosed method of pulse width modulation, both edges of each pulse of a carrier pulse train are equally modulated by a time proportional to sin .theta., where .theta. is the angular displacement of the pulse center at the motor stator frequency from a fixed reference point on the carrier waveform. The carrier waveform frequency is a multiple of the motor stator frequency. The modulated pulse train is then applied to each of the motor phase inputs with respective phase shifts of 120.degree. at the stator frequency. Switching control commands for electronic switches in the inverter are stored in a random access memory (RAM) and the locations of the RAM are successively read out in a cyclic manner, each bit of a given RAM location controlling a respective phase input of the motor. The DC power source preferably comprises rechargeable batteries and all but one of the electronic switches in the inverter can be disabled, the remaining electronic switch being part of a "flyback" DC-DC converter circuit for recharging the battery.

  1. Pulse combustion: an assessment of opportunities for increased efficiency

    SciTech Connect (OSTI)

    Brenchley, D.L.; Bomelburg, H.J.

    1984-12-01T23:59:59.000Z

    The results of a literature review on pulse combustion are discussed. Current, near-future, and potential opportunities for pulse combustion applications are summarized, and the barriers to developing and using pulse combustion technology are discussed, along with research and development needs. Also provided are the proceedings of a pulse combustion workshop held in May, 1984 in Seattle, Washington. (LEW)

  2. Time-spatial drift of decelerating electromagnetic pulses

    E-Print Network [OSTI]

    Nerukh, Dmitry

    Time-spatial drift of decelerating electromagnetic pulses Alexander G. Nerukh1* and Dmitry A dependent electromagnetic pulse generated by a current running laterally to the direction of the pulse propagation is considered in paraxial approximation. It is shown that the pulse envelope moves in the time

  3. Method for controlling energy density for reliable pulsed laser deposition of thin films

    SciTech Connect (OSTI)

    Dowden, P. C., E-mail: dowden@lanl.gov, E-mail: qxjia@lanl.gov; Bi, Z.; Jia, Q. X., E-mail: dowden@lanl.gov, E-mail: qxjia@lanl.gov [Center for Integrated Nanotechnologies, Division of Materials Physics and Applications, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2014-02-15T23:59:59.000Z

    We have established a methodology to stabilize the laser energy density on a target surface in pulsed laser deposition of thin films. To control the focused laser spot on a target, we have imaged a defined aperture in the beamline (so called image-focus) instead of focusing the beam on a target based on a simple “lens-focus.” To control the laser energy density on a target, we have introduced a continuously variable attenuator between the output of the laser and the imaged aperture to manipulate the energy to a desired level by running the laser in a “constant voltage” mode to eliminate changes in the lasers’ beam dimensions. This methodology leads to much better controllability/reproducibility for reliable pulsed laser deposition of high performance electronic thin films.

  4. Suppression of the asymmetric competition mode in the relativistic Ku-band coaxial transit-time oscillator

    SciTech Connect (OSTI)

    Ling, Junpu; He, Juntao; Zhang, Jiande; Jiang, Tao; Wang, Lei [College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073 (China)

    2014-10-15T23:59:59.000Z

    A relativistic Ku-band coaxial transit-time oscillator has been proposed in our previous work. In the experiments, we find that the asymmetric competition mode in the device limits the microwave power with the increase of the input electric power. For solving such a problem, the methods for analysis and suppression of the asymmetric competition mode in the device are investigated theoretically and experimentally. It is shown that the structure and the material of the collector, the concentricity, and the electron emission uniformity play an important part in the suppression of the asymmetric competition mode in the relativistic Ku-band transit-time oscillator. In the subsequent experiments, the asymmetric mode was suppressed effectively. At a low guiding magnetic field of 0.7?T, a microwave pulse with power of 1?GW, frequency of 14.3?GHz close to the simulation one, and efficiency of 20% was generated.

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

    SciTech Connect (OSTI)

    Nong, Hanond, E-mail: Nong.Hanond@rub.de; Markmann, Sergej; Hekmat, Negar; Jukam, Nathan, E-mail: Nathan.Jukam@rub.de [Arbeitsgruppe Terahertz Spektroskopie und Technologie, Ruhr-Universität Bochum, Bochum 44780 (Germany); Pal, Shovon [Arbeitsgruppe Terahertz Spektroskopie und Technologie, Ruhr-Universität Bochum, Bochum 44780 (Germany); Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, Bochum 44780 (Germany); Mohandas, Reshma A.; Dean, Paul; Li, Lianhe; Linfield, Edmund H.; Giles Davies, A. [School of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT (United Kingdom); Wieck, Andreas D. [Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, Bochum 44780 (Germany)

    2014-09-15T23:59:59.000Z

    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 tunes 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.

  6. Feedback stabilization of resistive shell modes in a reversed field pinch

    SciTech Connect (OSTI)

    Fitzpatrick, R.; Yu, E.P. [Institute for Fusion Studies, Department of Physics, University of Texas at Austin, Austin, Texas 78712-1060 (United States)] [Institute for Fusion Studies, Department of Physics, University of Texas at Austin, Austin, Texas 78712-1060 (United States)

    1999-09-01T23:59:59.000Z

    A reactor relevant reversed field pinch (RFP) must be capable of operating successfully when surrounded by a close-fitting resistive shell whose L/R time is much {ital shorter} than the pulse length. Resonant modes are largely unaffected by the shell resistivity, provided that the plasma rotation is maintained against the breaking effect of nonaxisymmetric eddy currents induced in the shell. This may require an auxiliary momentum source, such as a neutral beam injector. Nonresonant modes are largely unaffected by plasma rotation, and are expected to manifest themselves as nonrotating {ital resistive shell modes} growing on the L/R time of the shell. A general RFP equilibrium is subject to many simultaneously unstable resistive shell modes; the only viable control mechanism for such modes in a RFP reactor is {ital active feedback}. It is demonstrated than an {ital N}-fold toroidally symmetric arrangement of feedback coils, combined with a strictly linear feedback algorithm, is capable of {ital simultaneously stabilizing} all intrinsically unstable resistive shell modes over a wide range of different RFP equilibria. The number of coils in the toroidal direction {ital N}, at any given poloidal angle, must be greater than, or equal to, the range of toroidal mode numbers of the unstable resistive shell modes. However, this range is largely determined by the aspect-ratio of the device. The optimum coil configuration corresponds to one in which each feedback coil slightly overlaps its immediate neighbors in the toroidal direction. The critical current which must be driven around each feedback coils is, at most, a few percent of the equilibrium toroidal plasma current. The feedback scheme is robust to small deviations from pure {ital N}-fold toroidal symmetry or a pure linear response of the feedback circuits. {copyright} {ital 1999 American Institute of Physics.}

  7. Pulse homodyne field disturbance sensor

    DOE Patents [OSTI]

    McEwan, T.E.

    1997-10-28T23:59:59.000Z

    A field disturbance sensor operates with relatively low power, provides an adjustable operating range, is not hypersensitive at close range, allows co-location of multiple sensors, and is inexpensive to manufacture. The sensor includes a transmitter that transmits a sequence of transmitted bursts of electromagnetic energy. The transmitter frequency is modulated at an intermediate frequency. The sequence of bursts has a burst repetition rate, and each burst has a burst width and comprises a number of cycles at a transmitter frequency. The sensor includes a receiver which receives electromagnetic energy at the transmitter frequency, and includes a mixer which mixes a transmitted burst with reflections of the same transmitted burst to produce an intermediate frequency signal. Circuitry, responsive to the intermediate frequency signal indicates disturbances in the sensor field. Because the mixer mixes the transmitted burst with reflections of the transmitted burst, the burst width defines the sensor range. The burst repetition rate is randomly or pseudo-randomly modulated so that bursts in the sequence of bursts have a phase which varies. A second range-defining mode transmits two radio frequency bursts, where the time spacing between the bursts defines the maximum range divided by two. 12 figs.

  8. Pulse homodyne field disturbance sensor

    DOE Patents [OSTI]

    McEwan, Thomas E. (Livermore, CA)

    1997-01-01T23:59:59.000Z

    A field disturbance sensor operates with relatively low power, provides an adjustable operating range, is not hypersensitive at close range, allows co-location of multiple sensors, and is inexpensive to manufacture. The sensor includes a transmitter that transmits a sequence of transmitted bursts of electromagnetic energy. The transmitter frequency is modulated at an intermediate frequency. The sequence of bursts has a burst repetition rate, and each burst has a burst width and comprises a number of cycles at a transmitter frequency. The sensor includes a receiver which receives electromagnetic energy at the transmitter frequency, and includes a mixer which mixes a transmitted burst with reflections of the same transmitted burst to produce an intermediate frequency signal. Circuitry, responsive to the intermediate frequency signal indicates disturbances in the sensor field. Because the mixer mixes the transmitted burst with reflections of the transmitted burst, the burst width defines the sensor range. The burst repetition rate is randomly or pseudo-randomly modulated so that bursts in the sequence of bursts have a phase which varies. A second range-defining mode transmits two radio frequency bursts, where the time spacing between the bursts defines the maximum range divided by two.

  9. Batch-mode vs Online-mode Supervised Learning Motivations for Artificial Neural Networks

    E-Print Network [OSTI]

    Wehenkel, Louis

    Batch-mode vs Online-mode Supervised Learning Motivations for Artificial Neural Networks Linear ANN-mode vs Online-mode Supervised Learning Motivations for Artificial Neural Networks Linear ANN Models for Artificial Neural Networks Linear ANN Models Single neuron models Single layer models Nonlinear ANN Models

  10. The Development of the Electrically Controlled High Power RF Switch and Its Application to Active RF Pulse Compression Systems

    SciTech Connect (OSTI)

    Guo, Jiquan; /SLAC

    2009-03-20T23:59:59.000Z

    In the past decades, there has been increasing interest in pulsed high power RF sources for building high-gradient high-energy particle accelerators. Passive RF pulse compression systems have been used in many applications to match the available RF sources to the loads requiring higher RF power but a shorter pulse. Theoretically, an active RF pulse compression system has the advantage of higher efficiency and compactness over the passive system. However, the key component for such a system an element capable of switching hundreds of megawatts of RF power in a short time compared to the compressed pulse width is still an open problem. In this dissertation, we present a switch module composed of an active window based on the bulk effects in semiconductor, a circular waveguide three-port network and a movable short plane, with the capability to adjust the S-parameters before and after switching. The RF properties of the switch module were analyzed. We give the scaling laws of the multiple-element switch systems, which allow the expansion of the system to a higher power level. We present a novel overmoded design for the circular waveguide three-port network and the associated circular-to-rectangular mode-converter. We also detail the design and synthesis process of this novel mode-converter. We demonstrate an electrically controlled ultra-fast high power X-band RF active window built with PIN diodes on high resistivity silicon. The window is capable of handling multi-megawatt RF power and can switch in 2-300ns with a 1000A current driver. A low power active pulse compression experiment was carried out with the switch module and a 375ns resonant delay line, obtaining 8 times compression gain with a compression ratio of 20.

  11. Study on electrical characteristics of barrier-free atmospheric air diffuse discharge generated by nanosecond pulses and long wire electrodes

    SciTech Connect (OSTI)

    Li, Lee, E-mail: leeli@mail.hust.edu.cn; Liu, Yun-Long; Teng, Yun; Liu, Lun; Pan, Yuan [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, School of Electric and Electronic Engineering, Huazhong University of Science and Technology (HUST), Wuhan 430074 (China)

    2014-07-15T23:59:59.000Z

    In room-temperature atmospheric air, the large-scale diffuse plasmas can be generated via high-voltage nanosecond pulses with short rise-time and wire electrodes. Diffuse discharge with the wire electrode length up to 110.0?cm and the discharge spacing of several centimeters has been investigated in this paper. Electrical characteristics of diffuse discharge have been analyzed by their optical photographs and measuring of the voltage and current waveforms. Experimental results show the electrode spacing, and the length of wire electrodes can influence the intensity and mode transition of diffuse discharge. The characteristic of current waveforms is that there are several current oscillation peaks at the time of applied pulsed voltage peak, and at the tail of applied pulse, the conduction current component will compensate the displacement one so that the measured current is unidirectional in diffuse discharge mode. The transition from diffuse discharge to arc discharge is always with the increasing of conduction current density. As for nanosecond pulses with long tail, the long wire electrodes are help for generating non-equilibrium diffuse plasmas.

  12. Long Term by Group

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of Science (SC)Integrated Codes |Is Your HomeLatestCenterLogging in Logging inLogisticsLong Term

  13. GENERAL TERMS & CONDITIONS

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of Science (SC) Environmental AssessmentsGeoffrey Campbell isOklahoma City,GENERAL TERMS &

  14. Stable mode-locked operation of a low repetition rate diode-pumped Nd:GdVO4 laser by combining

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    (2005). 2. F. Dausinger, H. Hügel, V. Konov: "Micro-machining with ultra-short laser pulses, from basicStable mode-locked operation of a low repetition rate diode-pumped Nd:GdVO4 laser by combining stabilised Nd:GdVO4 laser with low repetition rate by combining quadratic polarisation switching

  15. Injection locked oscillator system for pulsed metal vapor lasers

    DOE Patents [OSTI]

    Warner, Bruce E. (Livermore, CA); Ault, Earl R. (Dublin, CA)

    1988-01-01T23:59:59.000Z

    An injection locked oscillator system for pulsed metal vapor lasers is disclosed. The invention includes the combination of a seeding oscillator with an injection locked oscillator (ILO) for improving the quality, particularly the intensity, of an output laser beam pulse. The present invention includes means for matching the first seeder laser pulses from the seeding oscillator to second laser pulses of a metal vapor laser to improve the quality, and particularly the intensity, of the output laser beam pulse.

  16. Shifted-elementary-mode representation for partially coherent vectorial fields

    E-Print Network [OSTI]

    Tervo, Jani; Vahimaa, Pasi; Wyrowski, Frank

    2010-01-01T23:59:59.000Z

    A representation of partially spatially coherent and partially polarized stationary electromagnetic fields is given in terms of mutually uncorrelated, transversely shifted, fully coherent and polarized elementary electric-field modes. This representation allows one to propagate non-paraxial partially coherent vector fields using techniques for spatially fully coherent fields, which are numerically far more efficient than methods for propagating correlation functions. A procedure is given to determine the elementary modes from the radiant intensity and the far-zone polarization properties of the entire field. The method is applied to quasihomogeneous fields with rotationally symmetric cosine-modulated radiant intensity distributions. This is an adequate model for fields emitted by, e.g., many light-emitting diodes.

  17. Excitation of Kaluza-Klein gravitational mode

    E-Print Network [OSTI]

    Kunihito Uzawa; Yoshiyuki Morisawa; Shinji Mukohyama

    2000-04-10T23:59:59.000Z

    We investigate excitation of Kaluza-Klein modes due to the parametric resonance caused by oscillation of radius of compactification. We consider a gravitational perturbation around a D-dimensional spacetime, which we compactify on a (D-4)-sphere to obtain a 4-dimensional theory. The perturbation includes the so-called Kaluza-Klein modes, which are massive in 4-dimension, as well as zero modes, which is massless in 4-dimension. These modes appear as scalar, vector and second-rank symmetric tensor fields in the 4-dimensional theory. Since Kaluza-Klein modes are troublesome in cosmology, quanta of these Kaluza-Klein modes should not be excited abundantly. However, if radius of compactification oscillates, then masses of Kaluza-Klein modes also oscillate and, thus, parametric resonance of Kaluza-Klein modes may occur to excite their quanta. In this paper we consider part of Kaluza-Klein modes which correspond to massive scalar fields in 4-dimension and investigate whether quanta of these modes are excited or not in the so called narrow resonance regime of the parametric resonance. We conclude that at least in the narrow resonance regime quanta of these modes are not excited so catastrophically.

  18. Aperiodic dynamical decoupling sequences in presence of pulse errors

    E-Print Network [OSTI]

    Wang, Zhi-Hui

    2011-01-01T23:59:59.000Z

    Dynamical decoupling (DD) is a promising tool for preserving the quantum states of qubits. However, small imperfections in the control pulses can seriously affect the fidelity of decoupling, and qualitatively change the evolution of the controlled system at long times. Using both analytical and numerical tools, we theoretically investigate the effect of the pulse errors accumulation for two aperiodic DD sequences, the Uhrig's DD UDD) protocol [G. S. Uhrig, Phys. Rev. Lett. {\\bf 98}, 100504 (2007)], and the Quadratic DD (QDD) protocol [J. R. West, B. H. Fong and D. A. Lidar, Phys. Rev. Lett {\\bf 104}, 130501 (2010)]. We consider the implementation of these sequences using the electron spins of phosphorus donors in silicon, where DD sequences are applied to suppress dephasing of the donor spins. The dependence of the decoupling fidelity on different initial states of the spins is the focus of our study. We investigate in detail the initial drop in the DD fidelity, and its long-term saturation. We also demonstra...

  19. High-stability time-domain balanced homodyne detector for ultrafast optical pulse applications

    E-Print Network [OSTI]

    Merlin Cooper; Christoph Söller; Brian J. Smith

    2013-03-25T23:59:59.000Z

    Low-noise, efficient, phase-sensitive time-domain optical detection is essential for foundational tests of quantum physics based on optical quantum states and the realization of numerous applications ranging from quantum key distribution to coherent classical telecommunications. Stability, bandwidth, efficiency, and signal-to-noise ratio are crucial performance parameters for effective detector operation. Here we present a high-bandwidth, low-noise, ultra-stable time-domain coherent measurement scheme based on balanced homodyne detection ideally suited to characterization of quantum and classical light fields in well-defined ultrashort optical pulse modes.

  20. RF study and simulations of a C-band Barrel Open Cavity (BOC) pulse compressor

    E-Print Network [OSTI]

    Shu, Guan; He, Xiang

    2014-01-01T23:59:59.000Z

    This paper focuses on the RF study of a C-band(5712MHz) BOC pulse compressor. The operating principle of BOC is presented and the technical specifications are determined. The main components of BOC such as the cavity, the matching waveguide, the coupling slots and the tuning rings were numerically simulated by 3-D codes software HFSS and CST Microwave Studio(MWS). The "whispering gallery" mode TM6,1,1 with an unload Q of 100000 was chosen to oscillate in the cavity. An energy multiplication factor of 1.99 and a peak power gain of 6.34 were achieved theoretically.

  1. Hidden explosives detector employing pulsed neutron and x-ray interrogation

    DOE Patents [OSTI]

    Schultz, Frederick J. (Oak Ridge, TN); Caldwell, John T. (Los Alamos, NM)

    1993-01-01T23:59:59.000Z

    Methods and systems for the detection of small amounts of modern, highly-explosive nitrogen-based explosives, such as plastic explosives, hidden in airline baggage. Several techniques are employed either individually or combined in a hybrid system. One technique employed in combination is X-ray imaging. Another technique is interrogation with a pulsed neutron source in a two-phase mode of operation to image both nitrogen and oxygen densities. Another technique employed in combination is neutron interrogation to form a hydrogen density image or three-dimensional map. In addition, deliberately-placed neutron-absorbing materials can be detected.

  2. Hidden explosives detector employing pulsed neutron and x-ray interrogation

    DOE Patents [OSTI]

    Schultz, F.J.; Caldwell, J.T.

    1993-04-06T23:59:59.000Z

    Methods and systems for the detection of small amounts of modern, highly-explosive nitrogen-based explosives, such as plastic explosives, hidden in airline baggage. Several techniques are employed either individually or combined in a hybrid system. One technique employed in combination is X-ray imaging. Another technique is interrogation with a pulsed neutron source in a two-phase mode of operation to image both nitrogen and oxygen densities. Another technique employed in combination is neutron interrogation to form a hydrogen density image or three-dimensional map. In addition, deliberately-placed neutron-absorbing materials can be detected.

  3. Performance comparison of pulse-pair and wavelets methods for the pulse Doppler weather radar

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    - eters. The radar reflectivity (Z), the radial velocity (Vr) and the spectral width of velocities (W). [1). Generally, the meteorological targets move with speeds lower than 50 m/secs. The Doppler Effect wouldPerformance comparison of pulse-pair and wavelets methods for the pulse Doppler weather radar

  4. Temporally propagated optical pulses, and what they reveal about dispersion handling

    E-Print Network [OSTI]

    Kinsler, Paul

    2015-01-01T23:59:59.000Z

    I derive a temporally propagated uni-directional optical pulse equation valid in the few cycle limit. Temporal propagation is advantageous because it naturally preserves causality, unlike the competing spatially propagated models. The approach generates exact coupled bi-directional equations, which can be efficiently approximated down to a uni-directional form in cases where an optical pulse changes little over one optical cycle. It also also allows a direct term-to-term comparison of an exact bi-directional theory with an approximate uni-directional theory. Notably, temporal propagation handles dispersion in a different way, and this difference serves to highlight existing approximations inherent in spatially propagated treatments of dispersion. Accordingly, I emphasise the need for future work in clarifying the limitations of the dispersion conversion required by these types of approaches; since the only alternative in the few cycle limit may be to resort to the much more computationally intensive full Maxw...

  5. Seismic pulse propagation with constant Q and stable probability distributions

    E-Print Network [OSTI]

    Francesco Mainardi; Massimo Tomirotti

    2010-08-07T23:59:59.000Z

    The one-dimensional propagation of seismic waves with constant Q is shown to be governed by an evolution equation of fractional order in time, which interpolates the heat equation and the wave equation. The fundamental solutions for the Cauchy and Signalling problems are expressed in terms of entire functions (of Wright type) in the similarity variable and their behaviours turn out to be intermediate between those for the limiting cases of a perfectly viscous fluid and a perfectly elastic solid. In view of the small dissipation exhibited by the seismic pulses, the nearly elastic limit is considered. Furthermore, the fundamental solutions for the Cauchy and Signalling problems are shown to be related to stable probability distributions with index of stability determined by the order of the fractional time derivative in the evolution equation.

  6. Long-term multipactor discharge in multicarrier systems

    SciTech Connect (OSTI)

    Anza, S.; Vicente, C.; Gimeno, B.; Boria, V. E.; Armendariz, J. [Aurora Software and Testing S.L., Parque Cientifico Universitat de Valencia, Poligono 'La Coma' s/n, 46980 Paterna (Spain); Departamento de Comunicaciones, Universidad Politecnica de Valencia Camino de Vera s/n, 46022 Valencia (Spain); Departamento de Fisica Aplicada y Electromagnetismo - ICMUV, Universitat de Valencia c/ Dr. Moliner, 50, 46100 Valencia (Spain); Departamento de Comunicaciones, Universidad Politecnica de Valencia Camino de Vera s/n, 46022 Valencia (Spain); Aurora Software and Testing S.L., Parque Cientifico Universitat de Valencia, Poligono 'La Coma' s/n, 46980 Paterna (Spain)

    2007-08-15T23:59:59.000Z

    A new mechanism of long-term multipactor in multicarrier systems is studied employing both analytical and numerical methods. In particular, the investigation is focused on the impact that a realistic secondary emission yield at low energies produces on the development of long term multipactor. A novel analytical model for this interperiod charge accumulation is presented using the traditional multipactor theory for parallel plates, and approximating the multicarrier signal as a single-carrier signal modulated by a pulsed signal envelope. The analytical predictions are verified by numerical simulations for a typical rectangular waveguide. The analytical and numerical results demonstrate that the susceptibility of the system to develop a long-term multipactor discharge increases with higher values of low-energy secondary emission yield.

  7. Radiographic X-Ray Pulse Jitter

    SciTech Connect (OSTI)

    Mitton, C. V., Good, D. E., Henderson, D. J., Hogge, K. W.

    2011-01-15T23:59:59.000Z

    The Dual Beam Radiographic Facility consists of two identical radiographic sources. Major components of the machines are: Marx generator, water-filled pulse-forming line (PFL), water-filled coaxial transmission line, three-cell inductive voltage adder, and rod-pinch diode. The diode pulse has the following electrical specifications: 2.25-MV, 60-kA, 60-ns. Each source has the following x-ray parameters: 1-mm-diameter spot size, 4-rad at 1 m, 50-ns full width half max. The x-ray pulse is measured with PIN diode detectors. The sources were developed to produce high resolution images on single-shot, high-value experiments. For this application it is desirable to maintain a high level of reproducibility in source output. X-ray pulse jitter is a key metric for analysis of reproducibility. We will give measurements of x-ray jitter for each machine. It is expected that x-ray pulse jitter is predominantly due to PFL switch jitter, and therefore a correlation of the two will be discussed.

  8. Thermal performance testing of two Thales 9310 pulse-tube cryocoolers for PHyTIR

    SciTech Connect (OSTI)

    Paine, Christopher G. [Jet Propulsion Laboratory, California Institute of Technology 4800 Oak Grove Drive, Pasadena CA 91109 (United States)

    2014-01-29T23:59:59.000Z

    PHyTIR is a NASA-funded technology demonstration for a near-term earth-observing instrument in the thermal infrared spectrum, intended for use in the HyspIRI mission. PHyTIR will use two Thales 9310 single-stage pulse tube cryocoolers, one to directly cool the FPA, the other to simulate a passive radiator. We report performance measurements for the two Thales 9310 cryocoolers intended for inclusion in the PHyTIR demonstrator.

  9. Time-resolved soft x-ray absorption setup using multi-bunch operation modes at synchrotrons

    SciTech Connect (OSTI)

    Stebel, L.; Sigalotti, P.; Ressel, B.; Cautero, G. [Sincrotrone Trieste, S.S. 14 km 163.5, Area Science Park, 34149 Basovizza (Italy); Malvestuto, M.; Capogrosso, V. [Sincrotrone Trieste, S.S. 14 km 163.5, Area Science Park, 34149 Basovizza (Italy); Department of Physics, University of Trieste, via A. Valerio 2, 34127, Trieste (Italy); Bondino, F.; Magnano, E. [IOM-CNR, TASC laboratory, S.S. 14 km 163.5, Area Science Park, 34149 Basovizza (Italy); Parmigiani, F. [Sincrotrone Trieste, S.S. 14 km 163.5, Area Science Park, 34149 Basovizza (Italy); Department of Physics, University of Trieste, via A. Valerio 2, 34127, Trieste (Italy); IOM-CNR, TASC laboratory, S.S. 14 km 163.5, Area Science Park, 34149 Basovizza (Italy)

    2011-12-15T23:59:59.000Z

    Here, we report on a novel experimental apparatus for performing time-resolved soft x-ray absorption spectroscopy in the sub-ns time scale using non-hybrid multi-bunch mode synchrotron radiation. The present setup is based on a variable repetition rate Ti:sapphire laser (pump pulse) synchronized with the {approx}500 MHz x-ray synchrotron radiation bunches and on a detection system that discriminates and singles out the significant x-ray photon pulses by means of a custom made photon counting unit. The whole setup has been validated by measuring the time evolution of the L{sub 3} absorption edge during the melting and the solidification of a Ge single crystal irradiated by an intense ultrafast laser pulse. These results pave the way for performing synchrotron time-resolved experiments in the sub-ns time domain with variable repetition rate exploiting the full flux of the synchrotron radiation.

  10. Ultrafast dynamics and fragmentation of C60 in intense laser pulses

    E-Print Network [OSTI]

    Lin, Zheng-Zhe

    2014-01-01T23:59:59.000Z

    The radiation-induced fragmentation of the C60 fullerene was investigated by the tight-binding electron-ion dynamics simulations. In intense laser field, the breathing vibrational mode is much more strongly excited than the pentagonal-pinch mode. The fragmentation effect was found more remarkable at long wavelength lambda>800 nm rather than the resonant wavelengths due to the internal laser-induced dipole force, and the production ratio of C and C2 rapidly grows with increasing wavelength. By such fragmentation law, C atoms, C2 dimers or large Cn fragments could be selectively obtained by changing the laser wavelength. And the fragmentation of C60 by two laser pulses like the multi-step atomic photoionization was investigated.

  11. Pulse shaping effects on weld porosity in laser beam spot welds : contrast of long- & short- pulse welds.

    SciTech Connect (OSTI)

    Ellison, Chad M. (Honeywell FM& T, Kansas City, MO); Perricone, Matthew J. (R.J. Lee Group, Inc., Monroeville, PA); Faraone, Kevin M. (BWX Technologies, Inc., Lynchburg, VA); Norris, Jerome T.

    2007-10-01T23:59:59.000Z

    Weld porosity is being investigated for long-pulse spot welds produced by high power continuous output lasers. Short-pulse spot welds (made with a pulsed laser system) are also being studied but to a much small extent. Given that weld area of a spot weld is commensurate with weld strength, the loss of weld area due to an undefined or unexpected pore results in undefined or unexpected loss in strength. For this reason, a better understanding of spot weld porosity is sought. Long-pulse spot welds are defined and limited by the slow shutter speed of most high output power continuous lasers. Continuous lasers typically ramp up to a simmer power before reaching the high power needed to produce the desired weld. A post-pulse ramp down time is usually present as well. The result is a pulse length tenths of a second long as oppose to the typical millisecond regime of the short-pulse pulsed laser. This study will employ a Lumonics JK802 Nd:YAG laser with Super Modulation pulse shaping capability and a Lasag SLS C16 40 W pulsed Nd:YAG laser. Pulse shaping will include square wave modulation of various peak powers for long-pulse welds and square (or top hat) and constant ramp down pulses for short-pulse welds. Characterization of weld porosity will be performed for both pulse welding methods.

  12. RECOVERY OF POLLUTED ECOSYSTEMS: THE CASE FOR LONG-TERM STUDIES

    E-Print Network [OSTI]

    Power, Anne Marie

    in charting recovery from acute pollution incidents such as oil, chemical spills and pulses of mine1 RECOVERY OF POLLUTED ECOSYSTEMS: THE CASE FOR LONG-TERM STUDIES S. J. Hawkins1 , P. E. Gibbs1 , N, University of Southampton, SO17 1BJ, UK Recovery of marine ecosystems from known pollution has tended

  13. ARE PULSING SOLITARY WAVES RUNNING INSIDE THE SUN?

    SciTech Connect (OSTI)

    Wolff, Charles L., E-mail: charles.l.wolff@nasa.gov [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2012-09-10T23:59:59.000Z

    A precise sequence of frequencies-detected four independent ways-is interpreted as a system of solitary waves below the Sun's convective envelope. Six future observational or theoretical tests of this idea are suggested. Wave properties (rotation rates, radial energy distribution, nuclear excitation strength) follow from conventional dynamics of global oscillation modes after assuming a localized nuclear term strong enough to perturb and hold mode longitudes into alignments that form 'families'. To facilitate future tests, more details are derived for a system of two dozen solitary waves 2 {<=} l {<=} 25. Wave excitation by {sup 3}He and {sup 14}C burning is complex. It spikes by factors M{sub 1} {<=} 10{sup 3} when many waves overlap in longitude but its long-time average is M{sub 2} {<=} 10. Including mixing can raise overall excitation to {approx}50 times that in a standard solar model. These spikes cause tiny phase shifts that tend to pull wave rotation rates toward their ideal values {proportional_to}[l(l + 1)]{sup -1}. A system like this would generate some extra nuclear energy in two spots at low latitude on opposite sides of the Sun. Each covers about 20 Degree-Sign of longitude. Above a certain wave amplitude, the system starts giving distinctly more nuclear excitation to some waves (e.g., l = 9, 14, and 20) than to neighboring l values. The prominence of l = 20 has already been reported. This transition begins at temperature amplitudes {Delta}T/T = 0.03 in the solar core for a typical family of modes, which corresponds to {delta}T/T {approx} 0.001 for one of its many component oscillation modes.

  14. INJECTION STRAIGHT PULSED MAGNET ERROR TOLERANCE STUDY FOR TOP-OFF INJECTION

    SciTech Connect (OSTI)

    Wang, G.M.; Shaftan; T.: Fliller; R.; Parker; B.; Heese; R.; Kowalski; S.; Willeke; F.

    2011-03-28T23:59:59.000Z

    NSLS II is designed to work in top-off injection mode. The injection straight includes a septum and four fast kicker magnets. The pulsed magnet errors will excite a betatron oscillation. This paper gives the formulas of each error contribution to the oscillation amplitude at various source points in the ring. These are compared with simulation results. Based on the simple formulas, we can specify the error tolerances on the pulsed magnets with the goal to minimize the injection transient and scale it to similar machines. The NSLS-II is a 3 GeV third generation synchrotron light source under construction at Brookhaven National Laboratory. Due to its short lifetime, NSLS-II storage ring requires the top-off injection (once per minute) during which the stored beam orbit is highly desired as transparent. But the errors, from the SR pulsed magnets at the injection straight - kickers (non-closed injection bump) and pulsed septum (time-dependent stray field), excite a stored beam betatron oscillation. The magnitude of the perturbation can be large disturning some of the user experiments. In 2010 injection straight review, based on the experts experiences in ALS, DIAMOND, SLS and SPEAR, we came to the conclusion that the acceptable oscillation amplitude at the long straight is set as 100 {micro}m (i.e. 0.7 {sigma}x) in horizontal plane and 12 {micro}m, 2.5 {sigma}y, in vertical plane for NSLS II. This paper gives the analysis estimate of the different error source tolerance from the pulse magnets and scales it to our requirements. The result is compared with simulation.

  15. Mirror Modes in the Heliosheath

    SciTech Connect (OSTI)

    Tsurutani, B. T. [Jet Propulsion Lab., Calif. Inst. Tech., Pasadena, CA (United States); Guarnieri, F. L. [UNIVAP, Sao Jose dos Campos, SP (Brazil); Echer, E. E. [INPE, Sao Jose dos Campos, SP (Brazil); Lakhina, G. S. [Indian Institute of Geomagnetism, Navi Mumbai (India); Verkhoglyadova, O. P. [CSPAR, Univ. Alabama, Huntsville, AL (United States)

    2011-01-04T23:59:59.000Z

    Mirror mode (MM) structures are identified in the Voyager 1 heliosheath magnetic field data. Their characteristics are: (1) quasiperiodic structures with a typical scale size of {approx}57 {rho}{sub p}(proton gyroradii), (2) little or no angular changes across the structures ({approx}3 deg. longitude and {approx}3 deg. latitude), and (3) a lack of sharp boundaries at the magnetic dip edges. It is proposed that the pickup of interstellar neutrals in the upstream region of the termination shock (TS) is the likely cause of MM instability during intervals when the IMF is nearly orthogonal to the solar wind flow direction. Concomitant (quasiperpendicular) shock compression of the MM structures at the TS and additional injection of pickup ions (PUIs) throughout the heliosheath will enhance MM growth.

  16. Precision lifetime measurement of the cesium $6P_{3/2}$ level using ultrafast pump-probe laser pulses

    E-Print Network [OSTI]

    Patterson, Brian M; Ehrenreich, Thomas; Gearba, Mirela A; Brooke, George M; Scoville, James; Knize, Randy J

    2014-01-01T23:59:59.000Z

    Using the inherent timing stability of pulses from a mode-locked laser, we have precisely measured the cesium $6P_{3/2}$ excited state lifetime. An initial pump pulse excites cesium atoms in two counter-propagating atomic beams to the $6P_{3/2}$ level. A subsequent synchronized probe pulse ionizes atoms which remain in the excited state, and the photo-ions are collected and counted. By selecting pump pulses which vary in time with respect to the probe pulses, we obtain a sampling of the excited state population in time, resulting in a lifetime value of 30.462(46) ns. The measurement uncertainty (0.15%) is larger than our previous report of 0.12% [Phys. Rev. A 84, 010501(R) (2011)] due to the inclusion of additional data and systematic errors. In this follow-up paper we present details of the primary systematic errors encountered in the measurement, which include atomic motion within the intensity profiles of the laser beams, quantum beating in the photo-ion signal, and radiation trapping. Improvements to furt...

  17. Pulse energy measurement at the SXR instrument

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Moeller, Stefan; Brown, Garth; Dakovski, Georgi; Hill, Bruce; Holmes, Michael; Loos, Jennifer; Maida, Ricardo; Paiser, Ernesto; Schlotter, William; Turner, Joshua J.; et al

    2015-05-01T23:59:59.000Z

    A gas monitor detector was implemented and characterized at the Soft X-ray Research (SXR) instrument to measure the average, absolute and pulse-resolved photon flux of the LCLS beam in the energy range between 280 and 2000 eV. The detector is placed after the monochromator and addresses the need to provide reliable absolute pulse energy as well as pulse-resolved measurements for the various experiments at this instrument. This detector provides a reliable non-invasive measurement for determining flux levels on the samples in the downstream experimental chamber and for optimizing signal levels of secondary detectors and for the essential need of datamore »normalization. The design, integration into the instrument and operation are described, and examples of its performance are given.« less

  18. Pulsed pyroelectric crystal-powered gamma source

    SciTech Connect (OSTI)

    Chen, A. X.; Antolak, A. J.; Leung, K.-N.; Raber, T. N.; Morse, D. H. [Sandia National Laboratories, Livermore, CA 94550 (United States)

    2013-04-19T23:59:59.000Z

    A compact pulsed gamma generator is being developed to replace radiological sources used in commercial, industrial and medical applications. Mono-energetic gammas are produced in the 0.4 - 1.0 MeV energy range using nuclear reactions such as {sup 9}Be(d,n{gamma}){sup 10}B. The gamma generator employs an RF-driven inductively coupled plasma ion source to produce deuterium ion current densities up to 2 mA/mm{sup 2} and ampere-level current pulses can be attained by utilizing an array extraction grid. The extracted deuterium ions are accelerated to approximately 300 keV via a compact stacked pyroelectric crystal system and then bombard the beryllium target to generate gammas. The resulting microsecond pulse of gammas is equivalent to a radiological source with curie-level activity.

  19. A Self-Biasing Pulsed Depressed Collector

    SciTech Connect (OSTI)

    Kemp, Mark A.; Jensen, Aaron; Neilson, Jeff; /SLAC

    2014-05-29T23:59:59.000Z

    Depressed collectors have been utilized successfully for many years to improve the electrical efficiency of vacuum electron devices. Increasingly, pulsed, high-peak power accelerator applications are placing a premium on electrical efficiency. As RF systems are responsible for a large percentage of the overall energy usage at accelerator laboratories, methods to improve upon the state-of-the-art in pulsed high-power sources are desired. This paper presents a technique for self-biasing the stages in a multistage depressed collector. With this technique, the energy lost during the rise and fall times of the pulse can be recovered, separate power supplies are not needed, and existing modulators can be retrofitted. Calculations show that significant cost savings can be realized with the implementation of this device in high-power systems. In this paper, the technique is described along with experimental demonstration. (auth)

  20. Pulsed atmospheric fluidized bed combustion. Final report

    SciTech Connect (OSTI)

    NONE

    1998-03-01T23:59:59.000Z

    ThermoChem, under contract to the Department of Energy, conducted extensive research, development and demonstration work on a Pulsed Atmospheric Fluidized Bed Combustor (PAFBC) to confirm that advanced technology can meet these performance objectives. The ThermoChem/MTCI PAFBC system integrates a pulse combustor with an atmospheric bubbling-bed type fluidized bed combustor (BFBC) In this modular configuration, the pulse combustor burns the fuel fines (typically less than 30 sieve or 600 microns) and the fluidized bed combusts the coarse fuel particles. Since the ThermoChem/MTCI PAFBC employs both the pulse combustor and the AFBC technologies, it can handle the full-size range of coarse and fines. The oscillating flow field in the pulse combustor provides for high interphase and intraparticle mass transfer rates. Therefore, the fuel fines essentially burn under kinetic control. Due to the reasonably high temperature (>1093 C but less than the temperature for ash fusion to prevent slagging), combustion of fuel fines is substantially complete at the exit of the pulse combustor. The additional residence time of 1 to 2 seconds in the freeboard of the PAFBC unit then ensures high carbon conversion and, in turn, high combustion efficiency. A laboratory unit was successfully designed, constructed and tested for over 600 hours to confirm that the PAFBC technology could meet the performance objectives. Subsequently, a 50,000 lb/hr PAFBC demonstration steam boiler was designed, constructed and tested at Clemson University in Clemson, South Carolina. This Final Report presents the detailed results of this extensive and successful PAFBC research, development and demonstration project.

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

    SciTech Connect (OSTI)

    Li Xuechen; Niu Dongying; Yin Zengqian [College of Physics Science and Technology, Hebei University, Baoding 071002 (China); Fang Tongzhen; Wang Long [Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2012-08-15T23:59:59.000Z

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

  2. Single mode terahertz quantum cascade amplifier

    E-Print Network [OSTI]

    Ren, Y; Wallis, R.; Shah, Y. D.; Jessop, D. S.; Degl'Innocenti, R.; Klimont, A.; Kamboj, V.; Beere, H. E.; Ritchie, D. A.

    2014-10-06T23:59:59.000Z

    coherent radiation with high signal to noise ratio are required. In fact such devices have already been demonstrated in the master-oscillator power amplifier scheme5 as well as a gain-switched amplifier for ultrafast pulses6. For the master... the amplification of short pulses. So in principle, the straightforward way to achieve a quantum casade (QC) amplifier would require a proper antireflective (AR) coating on the facet to fully suppress the feedback, thus the bare cavity gain could be exploited...

  3. Dispersion compensation for attosecond electron pulses

    SciTech Connect (OSTI)

    Hansen, Peter; Baumgarten, Cory; Batelaan, Herman; Centurion, Martin [Department of Physics and Astronomy, University of Nebraska-Lincoln, Lincoln, Nebraska 68588 (United States)

    2012-08-20T23:59:59.000Z

    We propose a device to compensate for the dispersion of attosecond electron pulses. The device uses only static electric and magnetic fields and therefore does not require synchronization to the pulsed electron source. Analogous to the well-known optical dispersion compensator, an electron dispersion compensator separates paths by energy in space. Magnetic fields are used as the dispersing element, while a Wien filter is used for compensation of the electron arrival times. We analyze a device with a size of centimeters, which can be applied to ultrafast electron diffraction and microscopy, and fundamental studies.

  4. Device for generation of pulsed corona discharge

    DOE Patents [OSTI]

    Gutsol, Alexander F. (San Ramon, CA); Fridman, Alexander (Marlton, NJ); Blank, Kenneth (Philadelphia, PA); Korobtsev, Sergey (Moscow, RU); Shiryaevsky, Valery (Moscow, RU); Medvedev, Dmitry (Moscow, RU)

    2012-05-08T23:59:59.000Z

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

  5. Spatiotemporal characterization of ultrashort optical vortex pulses

    E-Print Network [OSTI]

    Miranda, Miguel; Rudawski, Piotr; Guo, Chen; Harth, Anne; L'Huillier, Anne; Arnold, Cord L

    2015-01-01T23:59:59.000Z

    Generation of few-cycle optical vortex pulses is challenging due to the large spectral bandwidths, as most vortex generation techniques are designed for monochromatic light. In this work, we use a spiral phase plate to generate few-cycle optical vortices from an ultrafast titanium:sapphire oscillator, and characterize them in the spatiotemporal domain using a recently introduced technique based on spatially resolved Fourier transform spectrometry. The performance of this simple approach to the generation of optical vortices is analyzed from a wavelength dependent perspective, as well as in the spatiotemporal domain, allowing us to completely characterize ultrashort vortex pulses in space, frequency, and time.

  6. Pulse tube coolers for Meteosat third generation

    SciTech Connect (OSTI)

    Butterworth, James; Aigouy, Gérald; Chassaing, Clement; Debray, Benoît; Huguet, Alexandre [Air Liquide Advanced Technologies, 2 Rue de Clémencière, F-38600 Sassenage (France)

    2014-01-29T23:59:59.000Z

    Air Liquide's Large Pulse Tube Coolers (LPTC) will be used to cool the focal planes of the Infrared Sounder (IRS) and Flexible Combined Imager (FCI) instruments aboard the ESA/Eumetsat satellites Meteosat Third Generation (MTG). This cooler consists of an opposed piston linear compressor driving a pulse tube cold head and the associated drive electronics including temperature regulation and vibration cancellation algorithms. Preparations for flight qualification of the cooler are now underway. In this paper we present results of the optimization and qualification activities as well as an update on endurance testing.

  7. A review of the Seabrook Station Probabilistic Safety Assessment: Containment failure modes and radiological source terms

    SciTech Connect (OSTI)

    Khatib-Rahbar, M.; Agrawal, A.K.; Ludewig, H.; Pratt, W.T.

    1987-03-01T23:59:59.000Z

    A technical review and evaluation of the Seabrook Station Probabilistic Safety Assessment has been performed. It is determined that (1) containment response to severe core melt accidents is judged to be an important factor in mitigating the consequences, (2) failure during the first few hours after core melt is also unlikely and the timing of overpressure failure is very long compared to WASH-1400, (3) the point-estimate radiological releases are comparable in magnitude to those used in WASH-1400, and (4) the energy of release is somewhat higher than for the previously reviewed studies.

  8. Microsoft PowerPoint - Arseneau_EIA_ShortTermDriversofEnergyPrices.ppt [Compatibility Mode]

    U.S. Energy Information Administration (EIA) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov YouKizildere IRaghuraji Agro IndustriesTownDells,1Stocks Nov-14 Dec-14 Jan-15LiquidBG North AmericaMarkets: The

  9. Real Time Pulse Pile-up Recovery in a High Throughput Digital Pulse Processor

    SciTech Connect (OSTI)

    Scoullar, Paul A. B.; McLean, Chris C. [Southern Innovation, Melbourne (Australia); Evans, Rob J. [Department of Electrical and Electronic Engineering, University of Melbourne (Australia)

    2011-12-13T23:59:59.000Z

    Detection and measurement of radiation is used extensively for non-invasive material characterization in a range of industries. However, many practical applications are frustrated by pulse pile-up within the detector. Pulse pile-up, which occurs when multiple radiation events arrive within the temporal resolving time of the detector, degrades the fidelity of subsequent material analysis. Traditional pulse processing techniques use fast digital filters and logic circuits to detect piled-up events and discard the corrupted data, however, this leads to substantial detector dead time. Consequently, there is considerable interest in more complex signal-processing algorithms to extend the performance of pulse processors and improve material characterization techniques. We present a technology for real-time decoding of pulse pile-up events. It is a model-based signal-processing algorithm able to accurately characterize the number, time-of-arrival and energy of all events in the detector output. Even in the presence of severe multi-pulse pile-up, the composite events are decoded and the energy and time-of-arrival recovered. The technology has been evaluated using a range of detectors, sources and count rates. An exceptional improvement over traditional pulse processing techniques is demonstrated.

  10. An 8-GW long-pulse generator based on Tesla transformer and pulse forming network

    SciTech Connect (OSTI)

    Su, Jiancang; Zhang, Xibo; Li, Rui; Zhao, Liang, E-mail: zhaoliang0526@163.com; Sun, Xu; Wang, Limin; Zeng, Bo; Cheng, Jie; Wang, Ying; Peng, Jianchang; Song, Xiaoxin [Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi'an, Shaanxi 710024 (China)

    2014-06-15T23:59:59.000Z

    A long-pulse generator TPG700L based on a Tesla transformer and a series pulse forming network (PFN) is constructed to generate intense electron beams for the purpose of high power microwave (HPM) generation. The TPG700L mainly consists of a 12-stage PFN, a built-in Tesla transformer in a pulse forming line, a three-electrode gas switch, a transmission line with a trigger, and a load. The Tesla transformer and the compact PFN are the key technologies for the development of the TPG700L. This generator can output electrical pulses with a width as long as 200 ns at a level of 8 GW and a repetition rate of 50 Hz. When used to drive a relative backward wave oscillator for HPM generation, the electrical pulse width is about 100 ns on a voltage level of 520 kV. Factors affecting the pulse waveform of the TPG700L are also discussed. At present, the TPG700L performs well for long-pulse HPM generation in our laboratory.

  11. Phase Modulator Programming to Get Flat Pulses with Desired Length and Power from the CTF3 Pulse Compressors

    E-Print Network [OSTI]

    Shaker, Seyd Hamed; Skowronski, Piotr; Syratchev, Igor; Tecker, Frank

    2010-01-01T23:59:59.000Z

    The pulse compressor is located after the klystron to increase the power peak by storing the energy at the beginning and releasing it near the end of klystron output pulse. In the CTF3 pulse compressors a doubling of the peak power is achieved according to our needs and the machine parameters. The magnitude of peak power, pulse length and flatness can be controlled by using a phase modulator for the input signal of klystrons. A C++ code is written to simulate the pulse compressor behaviour according to the klystron output pulse power. By manually changing the related parameters in the code for the best match, the quality factor and the filling time of pulse compressor cavities can be determined. This code also calculates and sends the suitable phase to the phase modulator according to the klystron output pulse power and the desired pulse length and peak power

  12. A NEW METHOD OF PULSE-WISE SPECTRAL ANALYSIS OF GAMMA-RAY BURSTS

    SciTech Connect (OSTI)

    Basak, Rupal; Rao, A. R., E-mail: rupalb@tifr.res.in, E-mail: arrao@tifr.res.in [Tata Institute of Fundamental Research, Mumbai-400005 (India)

    2013-05-10T23:59:59.000Z

    Time-resolved spectral analysis, though a very promising method to understand the emission mechanism of gamma-ray bursts (GRBs), is difficult to implement in practice because of poor statistics. We present a new method for pulse-wise time-resolved spectral study of the individual pulses of GRBs, using the fact that many spectral parameters are either constants or smooth functions of time. We use this method for the two pulses of GRB 081221, the brightest GRB with separable pulses. We choose, from the literature, a set of possible models that includes the Band model, blackbody with a power law (BBPL), and a collection of blackbodies with a smoothly varying temperature profile, along with a power law (mBBPL), and two blackbodies with a power law (2BBPL). First, we perform a time-resolved study to confirm the spectral parameter variations, and then we construct the new model to perform a joint spectral fit. We find that any photospheric emission in terms of blackbodies is required mainly in the rising parts of the pulses and the falling part can be adequately explained in terms of the Band model, with the low-energy photon index within the regime of synchrotron model. Interestingly, we find that 2BBPL is comparable or sometimes even better, though marginally, than the Band model, in all episodes. Consistent results are also obtained for the brightest GRB of Fermi era-GRB 090618. We point out that the method is generic enough to test any spectral model with well-defined parameter variations.

  13. Tensor B mode and stochastic Faraday mixing

    E-Print Network [OSTI]

    Massimo Giovannini

    2014-06-12T23:59:59.000Z

    This paper investigates the Faraday effect as a different source of B mode polarization. The E mode polarization is Faraday rotated provided a stochastic large-scale magnetic field is present prior to photon decoupling. In the first part of the paper we discuss the case where the tensor modes of the geometry are absent and we argue that the B mode recently detected by the Bicep2 collaboration cannot be explained by a large-scale magnetic field rotating, through the Faraday effect, the well established E mode polarization. In this case, the observed temperature autocorrelations would be excessively distorted by the magnetic field. In the second part of the paper the formation of Faraday rotation is treated as a stationary, random and Markovian process with the aim of generalizing a set of scaling laws originally derived in the absence of the tensor modes of the geometry. We show that the scalar, vector and tensor modes of the brightness perturbations can all be Faraday rotated even if the vector and tensor parts of the effect have been neglected, so far, by focussing the attention on the scalar aspects of the problem. The mixing between the power spectra of the E mode and B mode polarizations involves a unitary transformation depending nonlinearly on the Faraday rotation rate. The present approach is suitable for a general scrutiny of the polarization observables and of their frequency dependence.

  14. Optimization of pulsed-DEER measurements for Gd-based labels...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Optimization of pulsed-DEER measurements for Gd-based labels: choice of operational frequencies, pulse durations and positions, Optimization of pulsed-DEER measurements for...

  15. Mode-locked Lasers Applied to Deflecting a Near Earth Object on Collision Course with Earth

    E-Print Network [OSTI]

    Fork, Richard; Burgess, Luke; Bergstue, Grant

    2013-01-01T23:59:59.000Z

    We consider synchronized trains of sub-picosecond pulses generated by mode-locked lasers applied to deflection of near Earth objects (NEO) on collision course with Earth. Our method is designed to avoid a predicted collision of the NEO with Earth by at least the diameter of Earth. We estimate deflecting a 10,000 MT NEO, such as the asteroid which struck Earth near Chelyabinsk, Russia to be feasible within several months using average power in the ten kilowatt range. We see this deflection method as scalable to larger NEO to a degree not possible using continuous laser systems.

  16. Long-term testing

    SciTech Connect (OSTI)

    Ferber, M.; Graves, G.A. Jr.

    1994-12-31T23:59:59.000Z

    Land-based gas turbines are significantly different from automotive gas turbines in that they are designed to operate for 50,000 h or greater (compared to 5,000--10,000 h). The primary goal of this research is to determine the long-term survivability of ceramic materials for industrial gas turbine applications. Research activities in this program focus on the evaluation of the static tensile creep and stress rupture (SR) behavior of three commercially available structural ceramics which have been identified by the gas turbine manufacturers as leading candidates for use in industrial gas turbines. For each material investigated, a minimum of three temperatures and four stresses will be used to establish the stress and temperature sensitivities of the creep and SR behavior. Because existing data for many candidate structural ceramics are limited to testing times less than 2,000 h, this program will focus on extending these data to times on the order of 10,000 h, which represents the lower limit of operating time anticipated for ceramic blades and vanes in gas turbine engines. A secondary goal of the program will be to investigate the possibility of enhancing life prediction estimates by combining interrupted tensile SR tests and tensile dynamic fatigue tests in which tensile strength is measured as a function of stressing rate. The third goal of this program will be to investigate the effects of water vapor upon the SR behavior of the three structural ceramics chosen for the static tensile studies by measuring the flexural strength as a function of stressing rate at three temperatures.

  17. Mode Shape Estimation Algorithms Under Ambient Conditions: A Comparative Review

    SciTech Connect (OSTI)

    Dosiek, Luke; Zhou, Ning; Pierre, John W.; Huang, Zhenyu; Trudnowski, Daniel J.

    2013-05-01T23:59:59.000Z

    Abstract—This paper provides a comparative review of five existing ambient electromechanical mode shape estimation algorithms, i.e., the Transfer Function (TF), Spectral, Frequency Domain Decomposition (FDD), Channel Matching, and Subspace Methods. It is also shown that the TF Method is a general approach to estimating mode shape and that the Spectral, FDD, and Channel Matching Methods are actually special cases of it. Additionally, some of the variations of the Subspace Method are reviewed and the Numerical algorithm for Subspace State Space System IDentification (N4SID) is implemented. The five algorithms are then compared using data simulated from a 17-machine model of the Western Electricity Coordinating Council (WECC) under ambient conditions with both low and high damping, as well as during the case where ambient data is disrupted by an oscillatory ringdown. The performance of the algorithms is compared using the statistics from Monte Carlo Simulations and results from measured WECC data, and a discussion of the practical issues surrounding their implementation, including cases where power system probing is an option, is provided. The paper concludes with some recommendations as to the appropriate use of the various techniques. Index Terms—Electromechanical mode shape, small-signal stability, phasor measurement units (PMU), system identification, N4SID, subspace.

  18. The Normal Modes of the Earth Lapo Boschi (lapo@erdw.ethz.ch)

    E-Print Network [OSTI]

    Boschi, Lapo

    ) is given by Newton's law of gravitation, ¨u(r, t) = V r - r |r - r|3 G(r )d3 r , (1) with G denoting Newton, with associated eigenfrequencies: the normal modes (free oscillations) of the Earth. Self-Gravitation to the gravity field caused by the Earth's deformation u(r, t) itself ("self-gravitation"). Those terms, how

  19. Cost-Effective Multi-Mode Offloading with peer-assisted communications

    E-Print Network [OSTI]

    Gorinsky, Sergey

    cost in terms of financial settlement, energy consump- tion, and user satisfaction. Our simulationsCost-Effective Multi-Mode Offloading with peer-assisted communications Ioannis Komnios a, , Fani caused by the ongoing explosive growth in mobile data traffic. In this paper, we propose Cost

  20. Temporal pulse tailoring in laser manufacturing technologies

    E-Print Network [OSTI]

    Peinke, Joachim

    5 Temporal pulse tailoring in laser manufacturing technologies Razvan Stoian1 , Matthias. Ultrafast lasers have gained momentum in material processing technolo- gies in response to requirements for quality material processing. 5.1 Introduction The demand for precision in laser material processing

  1. Pulse thermal energy transport/storage system

    DOE Patents [OSTI]

    Weislogel, Mark M. (23133 Switzer Rd., Brookpark, OH 44142)

    1992-07-07T23:59:59.000Z

    A pulse-thermal pump having a novel fluid flow wherein heat admitted to a closed system raises the pressure in a closed evaporator chamber while another interconnected evaporator chamber remains open. This creates a large pressure differential, and at a predetermined pressure the closed evaporator is opened and the opened evaporator is closed. This difference in pressure initiates fluid flow in the system.

  2. Experimental Study of RF Pulsed Heating

    SciTech Connect (OSTI)

    Laurent, Lisa; Tantawi, Sami; Dolgashev, Valery; Nantista, Christopher; /SLAC; Higashi, Yasuo; /KEK, Tsukuba; Aicheler, Markus; Heikkinen, Samuli; Wuensch, Walter; /CERN

    2011-11-04T23:59:59.000Z

    Cyclic thermal stresses produced by rf pulsed heating can be the limiting factor on the attainable reliable gradients for room temperature linear accelerators. This is especially true for structures that have complicated features for wakefield damping. These limits could be pushed higher by using special types of copper, copper alloys, or other conducting metals in constructing partial or complete accelerator structures. Here we present an experimental study aimed at determining the potential of these materials for tolerating cyclic thermal fatigue due to rf magnetic fields. A special cavity that has no electric field on the surface was employed in these studies. The cavity shape concentrates the magnetic field on one flat surface where the test material is placed. The materials tested in this study have included oxygen free electronic grade copper, copper zirconium, copper chromium, hot isostatically pressed copper, single crystal copper, electroplated copper, Glidcop(reg. sign), copper silver, and silver plated copper. The samples were exposed to different machining and heat treatment processes prior to rf processing. Each sample was tested to a peak pulsed heating temperature of approximately 110 C and remained at this temperature for approximately 10 x 10{sup 6} rf pulses. In general, the results showed the possibility of pushing the gradient limits due to pulsed heating fatigue by the use of copper zirconium and copper chromium alloys.

  3. Pressure wave charged repetitively pulsed gas laser

    DOE Patents [OSTI]

    Kulkarny, Vijay A. (Redondo Beach, CA)

    1982-01-01T23:59:59.000Z

    A repetitively pulsed gas laser in which a system of mechanical shutters bracketing the laser cavity manipulate pressure waves resulting from residual energy in the cavity gas following a lasing event so as to draw fresh gas into the cavity and effectively pump spent gas in a dynamic closed loop.

  4. Ultimate Energy Densities for Electromagnetic Pulses

    E-Print Network [OSTI]

    Mankei Tsang

    2008-03-06T23:59:59.000Z

    The ultimate electric and magnetic energy densities that can be attained by bandlimited electromagnetic pulses in free space are calculated using an ab initio quantized treatment, and the quantum states of electromagnetic fields that achieve the ultimate energy densities are derived. The ultimate energy densities also provide an experimentally accessible metric for the degree of localization of polychromatic photons.

  5. Performance Assessment of Single Electrode-Supported Solid Oxide Cells Operating in the Steam Electrolysis Mode

    SciTech Connect (OSTI)

    X. Zhang; J. E. O'Brien; R. C. O'Brien; N. Petigny

    2011-11-01T23:59:59.000Z

    An experimental study is under way to assess the performance of electrode-supported solid-oxide cells operating in the steam electrolysis mode for hydrogen production. Results presented in this paper were obtained from single cells, with an active area of 16 cm{sup 2} per cell. The electrolysis cells are electrode-supported, with yttria-stabilized zirconia (YSZ) electrolytes ({approx}10 {mu}m thick), nickel-YSZ steam/hydrogen electrodes ({approx}1400 {mu}m thick), and modified LSM or LSCF air-side electrodes ({approx}90 {mu}m thick). The purpose of the present study is to document and compare the performance and degradation rates of these cells in the fuel cell mode and in the electrolysis mode under various operating conditions. Initial performance was documented through a series of voltage-current (VI) sweeps and AC impedance spectroscopy measurements. Degradation was determined through long-term testing, first in the fuel cell mode, then in the electrolysis mode. Results generally indicate accelerated degradation rates in the electrolysis mode compared to the fuel cell mode, possibly due to electrode delamination. The paper also includes details of an improved single-cell test apparatus developed specifically for these experiments.

  6. Non-stoichiometric material transfer in the pulsed laser deposition...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    the pulsed laser deposition of LaAlO3. Non-stoichiometric material transfer in the pulsed laser deposition of LaAlO3. Abstract: Inequivalent angular distributions have been found...

  7. IBEX - a pulsed power accelerator that generates no prepulse

    SciTech Connect (OSTI)

    Ramirez, J.J.; Corley, J.P.; Mazarakis, M.G.

    1983-01-01T23:59:59.000Z

    Intense relativistic electron beams are produced in vacuum diodes driven by pulsed power accelerators. For pulse widths approx. 100 nsec, pulse forming lines (PPL) are used to generate the accelerating voltage pulse. This pulse is produced by sequential switching of stored energy through two or more stages. Capacitance and/or inductive coupling usually results in the generation of a low level prepulse voltage some time during the switching sequence. This prepulse is known to have a substantial effect on the performance of the vacuum diode during the main accelerating pulse. Most accelerators use various schemes for reducing this prepulse to acceptable levels. The Isolated Blumlein PPL concept was developed at Sandia to allow for the generation of the main accelerating pulse without generating a prepulse voltage. This concept was implemented into the IBEX accelerator that generates a 4 MV, 100 kA, 20 nsec output pulse. Design and performance data are presented.

  8. Electromagnetically induced transparency with broadband laser pulses D. D. Yavuz

    E-Print Network [OSTI]

    Yavuz, Deniz

    Electromagnetically induced transparency with broadband laser pulses D. D. Yavuz Department pulses inside an atomic medium using electromag- netically induced transparency. Extending the suggestion.65. k Over the last decade, counterintuitive optical effects using electromagnetically induced

  9. Pulsed field separation of biomolecules in a nanofluidic filter array

    E-Print Network [OSTI]

    Reyes González, Noel I. (Noel Iván)

    2006-01-01T23:59:59.000Z

    In this work, pulsed electric fields are introduced as a means to enhance separation efficiency of biomolecules in a nanofluidic filter array channel. Separation under pulsed fields was tested using PBR322 DNA, Lambda Hind ...

  10. Mode I - mode II delamination fractrue toughness of a unidirectional graphite/epoxy composite 

    E-Print Network [OSTI]

    Vanderkley, Peter Stephen

    1981-01-01T23:59:59.000Z

    MODE I - MODE II DELAMINATION FRACTURE TOUGHNESS OF A UNIDIRECTIONAL GRAPHITE/EPOXY COMPOSITE A Thesis by PETER STEPHEN VANDERKLEY Submitted to the Graduate College of Texas ASM University in partial fulfillment of the requirement... for the degree of MASTER OF SCIENCE Demember 1981 Najor Subject: Mechanical Engineering MODE I - MODE II DELAMINATION FRACTURE TOUGHNESS OF A UNIDIRECTIONAL GRAPHITE/EPOXY COMPOSITE A Thesis by PETER STEPHEN VANDERKLEY Approved as to style and content by...

  11. Normalizable fermion modes in a holographic superconductor

    E-Print Network [OSTI]

    Steven S. Gubser; Fabio D. Rocha; Pedro Talavera

    2009-11-18T23:59:59.000Z

    We consider fermions in a zero-temperature superconducting anti-de Sitter domain wall solution and find continuous bands of normal modes. These bands can be either partially filled or totally empty and gapped. We present a semi-classical argument which approximately captures the main features of the normal mode spectrum.

  12. Theory of longitudinal modes in semiconductor lasers

    SciTech Connect (OSTI)

    Lau, K.Y.; Yariv, A.

    1982-05-01T23:59:59.000Z

    A theory of longitudinal mode lasing spectrum of semiconductor lasers is developed which takes into account the nonuniform carrier and photon distributions and local gain spectrum shifts inside lasers with low end mirror reflectivities. The theory gives results consistent with observed longitudinal mode behavior in lasers with reduced facet reflectivity.

  13. Broadband frequency mode entanglement in waveguided PDC

    E-Print Network [OSTI]

    Eckstein, Andreas

    2008-01-01T23:59:59.000Z

    We report the observation of beatings of the coincidence event rate in a Hong-Ou-Mandel interference (HOMI) between signal and idler photons from a parametric downconversion process inside a multi-mode KTP waveguide. As explanation we introduce bi-photonic states entangled in their broadband frequency modes and propose a suitable entanglement witness.

  14. Nonlinear mode coupling in rotating stars and the r-mode instability in neutron stars

    E-Print Network [OSTI]

    A. Katrin Schenk; Phil Arras; Eanna E. Flanagan; Saul A. Teukolsky; Ira Wasserman

    2001-07-11T23:59:59.000Z

    We develop the formalism required to study the nonlinear interaction of modes in rotating Newtonian stars in the weakly nonlinear regime. The formalism simplifies and extends previous treatments. At linear order, we elucidate and extend slightly a formalism due to Schutz, show how to decompose a general motion of a rotating star into a sum over modes, and obtain uncoupled equations of motion for the mode amplitudes under the influence of an external force. Nonlinear effects are added perturbatively via three-mode couplings. We describe a new, efficient way to compute the coupling coefficients, to zeroth order in the stellar rotation rate, using spin-weighted spherical harmonics. We apply this formalism to derive some properties of the coupling coefficients relevant to the nonlinear interactions of unstable r-modes in neutron stars, postponing numerical integrations of the coupled equations of motion to a later paper. From an astrophysical viewpoint, the most interesting result of this paper is that many couplings of r-modes to other rotational modes (modes with zero frequencies in the non-rotating limit) are small: either they vanish altogether because of various selection rules, or they vanish to lowest order in the angular velocity. In zero-buoyancy stars, the coupling of three r-modes is forbidden entirely and the coupling of two r-modes to one hybrid rotational mode vanishes to zeroth order in rotation frequency. In incompressible stars, the coupling of any three rotational modes vanishes to zeroth order in rotation frequency.

  15. Application of Yb:YAG short pulse laser system

    DOE Patents [OSTI]

    Erbert, Gaylen V.; Biswal, Subrat; Bartolick, Joseph M.; Stuart, Brent C.; Crane, John K.; Telford, Steve; Perry, Michael D.

    2004-07-06T23:59:59.000Z

    A diode pumped, high power (at least 20W), short pulse (up to 2 ps), chirped pulse amplified laser using Yb:YAG as the gain material is employed for material processing. Yb:YAG is used as the gain medium for both a regenerative amplifier and a high power 4-pass amplifier. A single common reflective grating optical device is used to both stretch pulses for amplification purposes and to recompress amplified pulses before being directed to a workpiece.

  16. Green Bank Telescope Studies of Giant Pulses from Millisecond Pulsars

    E-Print Network [OSTI]

    H. S. Knight; M. Bailes; R. N. Manchester; S. M. Ord; B. A. Jacoby

    2005-12-13T23:59:59.000Z

    We have conducted a search for giant pulses from four millisecond pulsars using the 100m Green Bank Telescope. Coherently dedispersed time-series from PSR J0218+4232 were found to contain giant pulses of very short intrinsic duration whose energies follow power-law statistics. The giant pulses are in phase with the two minima of the radio integrated pulse profile but are phase aligned with the peaks of the X-ray profile. Historically, individual pulses more than 10-20 times the mean pulse energy have been deemed to be ``giant pulses''. As only 4 of the 155 pulses had energies greater than 10 times the mean pulse-energy, we argue the emission mechanism responsible for giant pulses should instead be defined through: (a) intrinsic timescales of microsecond or nanosecond duration; (b) power-law energy statistics; and (c) emission occurring in narrow phase-windows coincident with the phase windows of non-thermal X-ray emission. Four short-duration pulses with giant-pulse characteristics were also observed from PSR B1957+20. As the inferred magnetic fields at the light cylinders of the millisecond pulsars that emit giant pulses are all very high, this parameter has previously been considered to be an indicator of giant pulse emissivity. However, the frequency of giant pulse emission from PSR~B1957+20 is significantly lower than for other millisecond pulsars that have similar magnetic fields at their light cylinders. This suggests that the inferred magnetic field at the light cylinder is a poor indicator of the rate of emission of giant pulses.

  17. Ultraslow Propagation of Squeezed Vacuum Pulses with Electromagnetically Induced Transparency

    E-Print Network [OSTI]

    Daisuke Akamatsu; Yoshihiko Yokoi; Manabu Arikawa; Satoshi Nagatsuka; Takahito Tanimura; Akira Furusawa; Mikio Kozuma

    2008-01-27T23:59:59.000Z

    We have succeeded in observing ultraslow propagation of squeezed vacuum pulses with electromagnetically induced transparency. Squeezed vacuum pulses (probe lights) were incident on a laser cooled 87Rb gas together with an intense coherent light (control light). A homodyne method sensitive to the vacuum state was employed for detecting the probe pulse passing through the gas. A delay of 3.1us was observed for the probe pulse having a temporal width of 10 us.

  18. Surface plasmon modes and the Casimir energy

    E-Print Network [OSTI]

    F. Intravaia; A. Lambrecht

    2005-07-01T23:59:59.000Z

    We show the influence of surface plasmons on the Casimir effect between two plane parallel metallic mirrors at arbitrary distances. Using the plasma model to describe the optical response of the metal, we express the Casimir energy as a sum of contributions associated with evanescent surface plasmon modes and propagative cavity modes. In contrast to naive expectations, the plasmonic modes contribution is essential at all distances in order to ensure the correct result for the Casimir energy. One of the two plasmonic modes gives rise to a repulsive contribution, balancing out the attractive contributions from propagating cavity modes, while both contributions taken separately are much larger than the actual value of the Casimir energy. This also suggests possibilities to tailor the sign of the Casimir force via surface plasmons.

  19. Saturation of the R-mode Instability

    E-Print Network [OSTI]

    Phil Arras; Eanna E. Flanagan; Sharon M. Morsink; A. Katrin Schenk; Saul A. Teukolsky; Ira Wasserman

    2003-02-11T23:59:59.000Z

    Rossby waves (r-modes) in rapidly rotating neutron stars are unstable because of the emission of gravitational radiation. We study saturation of this instability by nonlinear transfer of energy to stellar "inertial" oscillation modes. We present detailed calculations of stellar inertial modes in the WKB limit, their linear damping by bulk and shear viscosity, and the nonlinear coupling forces among these modes. The saturation amplitude is derived in the extreme limits of strong or weak driving by radiation reaction, as compared to the damping rate of low order inertial modes. We find the saturation energy is {\\it extremely small}, at least four orders of magnitude smaller than that found by previous investigators. We discuss the consequences of this result for spin evolution of young neutron stars, and neutron stars being spun up by accretion in Low Mass X-ray Binaries.We also discuss the detection of these gravitational waves by LIGO.

  20. Nonclassicality in two-mode BEC

    E-Print Network [OSTI]

    Sandip Kumar Giri; Biswajit Sen; C H Raymond Ooi; Anirban Pathak

    2013-07-05T23:59:59.000Z

    An analytic operator solution of a generalized quantum mechanical Hamiltonian of two-mode Bose Einstein condensates (BECs) is obtained and the same is used to investigate the nonclassical properties of the modes present in the system. Nonclassical characters are observed by means of single mode and intermodal squeezing, single mode and intermodal sub-Poissonian boson statistics and intermodal entanglement. In addition to the traditionally studied lower order nonclassical properties, signatures of higher order nonclassical characters of two-mode BEC systems are also obtained by investigating the possibility of higher order antibunching and higher order entanglement. The mutual relation among the observed nonclassicalities and their evolution (variation) with rescaled time and the ratio of the single boson tunneling amplitude ($\\varepsilon$) and the coupling constant for the intra-modal interaction ($\\kappa$) are also reported.

  1. Gravitational-wave modes from precessing black-hole binaries

    E-Print Network [OSTI]

    Michael Boyle; Lawrence E. Kidder; Serguei Ossokine; Harald P. Pfeiffer

    2014-09-22T23:59:59.000Z

    Gravitational waves from precessing black-hole binaries exhibit features that are absent in nonprecessing systems. The most prominent of these is a parity-violating asymmetry that beams energy and linear momentum preferentially along or opposite to the orbital angular momentum, leading to recoil of the binary. The asymmetry will appear as amplitude and phase modulations at the orbital frequency. For strongly precessing systems, it accounts for at least 3% amplitude modulation for binaries in the sensitivity band of ground-based gravitational-wave detectors, and can exceed 50% for massive systems. Such asymmetric features are also clearly visible when the waves are decomposed into modes of spin-weighted spherical harmonics, and are inherent in the waves themselves---rather than resulting from residual eccentricity in numerical simulations, or from mode-mixing due to precession. In particular, there is generically no instantaneous frame for which the mode decomposition will have any symmetry. We introduce a method to simplify the expressions for waveforms given in analytical relativity, which can be used to combine existing high-order waveforms for nonprecessing systems with expressions for the precessing contributions, leading to improved accuracy and a unified treatment of precessing and nonprecessing binaries. Using this method, it is possible to clarify the nature and the origins of the asymmetries and show the effects of asymmetry on recoils more clearly. We present post-Newtonian (PN) expressions for the waveform modes that include these terms, complete to the relative 2PN level in spin (proportional to $v^4/c^4$ times a certain combination of the spins). Comparing the results of those expressions to numerical results, we find good qualitative agreement. We also demonstrate how these expressions can be used to efficiently calculate waveforms for gravitational-wave astronomy.

  2. Information processing with longitudinal spectral decomposition of ultrafast pulses

    E-Print Network [OSTI]

    Fainman, Yeshaiahu

    Information processing with longitudinal spectral decomposition of ultrafast pulses Robert E of waveforms depending on whether their frequency response is or is not known a priori. Ultrafast pulses prove synthesis and detection relying on longitudinal spectral decomposition of subpicosecond optical pulses

  3. Colliding Laser Pulses for Laser-Plasma Accelerator Injection Control

    E-Print Network [OSTI]

    Geddes, Cameron Guy Robinson

    Colliding Laser Pulses for Laser-Plasma Accelerator Injection Control G. R. Plateau, , C. G. R acceleration is a key challenge to achieve compact, reliable, tunable laser-plasma accelerators (LPA) [1, 2]. In colliding pulse injection the beat between multiple laser pulses can be used to control energy, energy

  4. Enhanced subthreshold electron-positron production in short laser pulses

    E-Print Network [OSTI]

    A. I. Titov; H. Takabe; B. Kampfer; A. Hosaka

    2012-05-17T23:59:59.000Z

    The emission of electron-positron pairs off a probe photon propagating through a polarized short-pulsed electromagnetic (e.g.\\ laser) wave field is analyzed. A significant increase of the total cross section of pair production in the subthreshold region is found for decreasing laser pulse duration even in case of moderate laser pulse intensities.

  5. A new method for generating ultraintense and ultrashort laser pulses

    E-Print Network [OSTI]

    Loss, Daniel

    -cost ultrahigh-intensity laser systems. The field of amplification and compression of short laser pulses laser system, where the short laser pulse is amplified and compressed in plasma through resonantARTICLES A new method for generating ultraintense and ultrashort laser pulses JUN REN, WEIFENG

  6. Asymptotic description of pulsed ultrawideband electromagnetic beam field

    E-Print Network [OSTI]

    Oughstun, Kurt

    Asymptotic description of pulsed ultrawideband electromagnetic beam field propagation in dispersive of a pulsed ultrawideband electro- magnetic beam field as it propagates through a dispersive, attenuative evolution of the pulsed-beam field through a single-contour integral that is of the same form

  7. Limiter H-mode experiments on TFTR

    SciTech Connect (OSTI)

    Bush, C.E. (Oak Ridge National Lab., TN (USA)); Bretz, N.L.; Fredrickson, E.D.; McGuire, K.M.; Nazikian, R.; Park, H.K.; Schivell, J.; Taylor, G.; Bitter, M.; Budny, R.; Cohen, S.A.; Kilpatrick, S.J.; LeBlanc, B.; Manos, D.M.; Meade, D.; Paul, S.F.; Scott, S.D.; Stratton, B.C.; Synakowski, E.J.; Towner, H.H.; Wieland, R.M.; Arunasalam, V.; Bateman, G.; Bell, M.G.; Bell, R.; Boivin, R.; Cavallo, A.; Cheng, C.Z.; Chu, T.K.; Co

    1991-05-01T23:59:59.000Z

    Limiter H-modes with centrally peaked density profiles have been obtained in TFTR using a highly conditioned graphite limiter. The transition to these centrally peaked H-modes takes place from the supershot to the H-mode rather than the usual L- to H-mode transition observed on other tokamaks. Bidirectional beam heating is required to induce the transition. Density peaking factors, n{sub e}(0)/, greater than 2.3 are obtained and at the same time the H-mode characteristics are similar to those of limiter H-modes on other tokamaks, while the global confinement, {tau}{sub E}, can be >2.5 times L-mode scaling. The transport analysis of the data shows that transport in these H-modes is similar to that of supershots within the inner 0.6 m core of the plasma, but the stored electron energy (calculated using measured values of T{sub e} and n{sub e}) is higher for the H-mode at the plasma edge. Microwave scattering data for the edge plasma shows broad spectra at k = 5.5 cm{sup {minus}1} which begin at the drop in D{sub {alpha}} radiation and are strongly shifted in the electron diamagnetic drift direction. At the same time, beam emission spectroscopy (BES) shows a coherent mode near the boundary which propagates in the ion direction with m = 15--20 at 20--30 kHz. During the ELM event these apparent rotations cease and Mirnov fluctuations in the frequency range of 50--500 kHz increase in intensity. 16 refs., 8 figs.

  8. Observation of the long term stability of water stations in the Pierre Auger surface detector

    SciTech Connect (OSTI)

    Allekotte, I.; Arisaka, K.; Barnhill, D.; Bertou, Xavier; Bonifazi, C.; Healy, M.D.; Lee, J.; Medina, C.; Ohnuki, T.; Tripathi, A.

    2005-07-01T23:59:59.000Z

    The results of a study examining the long-term behavior of Pierre Auger surface detectors is presented. The station properties, such as water quality, liner reflectivity and the water level must be continuously monitored. Such monitoring provides information on the long-term stability of the detectors, which have been designed to operate for twenty years. Using pulse height and shapes of cosmic ray muons, water quality changes are monitored and a technique developed to identify and monitor long-term trends in the array.

  9. President's Message: Mid Term Report

    E-Print Network [OSTI]

    Rodriguez, Robert

    2008-01-01T23:59:59.000Z

    NEWSLETTER President’s Message Mid-Term Report What have wegoals outlined in my first message was to bolster membership

  10. Global synchronization of parallel processors using clock pulse width modulation

    DOE Patents [OSTI]

    Chen, Dong; Ellavsky, Matthew R.; Franke, Ross L.; Gara, Alan; Gooding, Thomas M.; Haring, Rudolf A.; Jeanson, Mark J.; Kopcsay, Gerard V.; Liebsch, Thomas A.; Littrell, Daniel; Ohmacht, Martin; Reed, Don D.; Schenck, Brandon E.; Swetz, Richard A.

    2013-04-02T23:59:59.000Z

    A circuit generates a global clock signal with a pulse width modification to synchronize processors in a parallel computing system. The circuit may include a hardware module and a clock splitter. The hardware module may generate a clock signal and performs a pulse width modification on the clock signal. The pulse width modification changes a pulse width within a clock period in the clock signal. The clock splitter may distribute the pulse width modified clock signal to a plurality of processors in the parallel computing system.

  11. Combining attosecond XUV pulses with coincidence spectroscopy

    SciTech Connect (OSTI)

    Sabbar, M., E-mail: msabbar@phys.ethz.ch; Heuser, S.; Boge, R.; Lucchini, M.; Cirelli, C.; Keller, U. [Department of Physics, ETH Zurich, 8093 Zurich (Switzerland); Gallmann, L. [Department of Physics, ETH Zurich, 8093 Zurich (Switzerland); Institute of Applied Physics, University of Bern, 3012 Bern (Switzerland)

    2014-10-15T23:59:59.000Z

    Here we present a successful combination of an attosecond beamline with a COLTRIMS apparatus, which we refer to as AttoCOLTRIMS. The setup provides either single attosecond pulses or attosecond pulse trains for extreme ultraviolet-infrared pump-probe experiments. We achieve full attosecond stability by using an active interferometer stabilization. The capability of the setup is demonstrated by means of two measurements, which lie at the heart of the COLTRIMS detector: firstly, we resolve the rotating electric field vector of an elliptically polarized few-cycle infrared laser field by attosecond streaking exploiting the access to the 3D momentum space of the charged particles. Secondly, we show streaking measurements on different atomic species obtained simultaneously in a single measurement making use of the advantage of measuring ions and electrons in coincidence. Both of these studies demonstrate the potential of the AttoCOLTRIMS for attosecond science.

  12. Electromagnetic Pulse from Final Gravitational Stellar Collapse

    E-Print Network [OSTI]

    P. D. Morley; Ivan Schmidt

    2002-01-30T23:59:59.000Z

    We employ an effective gravitational stellar final collapse model which contains the relevant physics involved in this complex phenomena: spherical radical infall in the Schwarzschild metric of the homogeneous core of an advanced star, giant magnetic dipole moment, magnetohydrodynamic material response and realistic equations of state (EOS). The electromagnetic pulse is computed both for medium size cores undergoing hydrodynamic bounce and large size cores undergoing black hole formation. We clearly show that there must exist two classes of neutron stars, separated by maximum allowable masses: those that collapsed as solitary stars (dynamical mass limit) and those that collapsed in binary systems allowing mass accretion (static neutron star mass). Our results show that the electromagnetic pulse spectrum associated with black hole formation is a universal signature, independent of the nuclear EOS. Our results also predict that there must exist black holes whose masses are less than the static neutron star stability limit.

  13. Solitary electromechanical pulses in Lobster neurons

    E-Print Network [OSTI]

    Gonzalez-Perez, Alfredo; Budvytyte, Rima; Villagran-Vargas, Edgar; Jackson, Andrew D; Heimburg, Thomas

    2015-01-01T23:59:59.000Z

    Investigations of nerve activity have focused predominantly on electrical phenomena. Nerves, however, are thermodynamic systems, and changes in temperature and in the dimensions of the nerve can also be observed during the action potential. Measurements of heat changes during the action potential suggest that the nerve pulse shares many characteristics with an adiabatic pulse. In the past, experiments by Iwasa & Tasaki demonstrated small changes in nerve thickness and length during the action potential. Such findings have led to the suggestion that the action potential may be related to electromechanical solitons traveling without dissipation. Here, we present ultrasensitive AFM recordings of mechanical changes on the order of 0.2 - 1.2 nm in the giant axons of the lobster. When stimulated at opposite ends of the same axon, colliding action potentials pass through one another and do not annihilate. These observations are consistent with a mechanical interpretation of the nervous impulse.

  14. Improvement of the Temporal Contrast of High-Power Laser Pulses

    E-Print Network [OSTI]

    high gain8 pass amplifier ultrafast pulse cleaner 107 preamplifierJ ultrafast pulse cleaner ASE for pulse amplification. In our laser system, we insert the preamplifier and ultrafast pulse cleaner before for optimizing the performance of the ultrafast pulse cleaner. After passing through the pulse cleaner, the high

  15. Source depth for solar p-modes

    E-Print Network [OSTI]

    Pawan Kumar; Sarbani Basu

    2000-06-15T23:59:59.000Z

    Theoretically calculated power spectra are compares with observed solar p-mode velocity power spectra over a range of mode degree and frequency. The depth for the sources responsible for exciting p-modes of frequency 2.0 mHz is determined from the asymmetry of their power spectra and found to be about 800 km below the photosphere for quadrupole sources and 150 km if sources are dipole. The source depth for high frequency oscillations of frequency greater than about 6 mHz is 180 (50) km for quadrupole (dipole) sources.

  16. Edge modes in band topological insulators

    E-Print Network [OSTI]

    Lukasz Fidkowski; T. S. Jackson; Israel Klich

    2011-05-09T23:59:59.000Z

    We characterize gapless edge modes in translation invariant topological insulators. We show that the edge mode spectrum is a continuous deformation of the spectrum of a certain gluing function defining the occupied state bundle over the Brillouin zone (BZ). Topologically non-trivial gluing functions, corresponding to non-trivial bundles, then yield edge modes exhibiting spectral flow. We illustrate our results for the case of chiral edge states in two dimensional Chern insulators, as well as helical edges in quantum spin Hall states.

  17. Laser cooling with ultrafast pulse trains

    E-Print Network [OSTI]

    David Kielpinski

    2003-06-14T23:59:59.000Z

    We propose a new laser cooling method for atomic species whose level structure makes traditional laser cooling difficult. For instance, laser cooling of hydrogen requires vacuum-ultraviolet laser light, while multielectron atoms need laser light at many widely separated frequencies. These restrictions can be eased by laser cooling on two-photon transitions with ultrafast pulse trains. Laser cooling of hydrogen, antihydrogen, and carbon appears feasible, and extension of the technique to molecules may be possible.

  18. The Homopolar Pulse Billet Heating Process

    E-Print Network [OSTI]

    Keith, R. E.; Weldon, W. F.

    1982-01-01T23:59:59.000Z

    - or gas-fired furnace machine. (7) Also during 1981, under the heating. Although most billet heating sponsorship of the Electric Power Research today is done using fuel-fired furnaces, Institute (EPRI), CEM-UT carried out a electric heating... obtained frDm Electromechanics at The University of Texas the EPRI study. at Austin (CEM-UT) has been engaged in research on large pulsed power supplies for use in experiments leading to controlled TEMPERATURE GRADIENTS IN BILLET HEATING...

  19. Pulsed atmospheric fluidized bed combustor apparatus

    DOE Patents [OSTI]

    Mansour, Momtaz N. (Columbia, MD)

    1993-10-26T23:59:59.000Z

    A pulsed atmospheric fluidized bed reactor system is disclosed and claimed along with a process for utilization of same for the combustion of, e.g. high sulfur content coal. The system affords a economical, ecologically acceptable alternative to oil and gas fired combustors. The apparatus may also be employed for endothermic reaction, combustion of waste products, e.g., organic and medical waste, drying materials, heating air, calcining and the like.

  20. Infrared nanosecond laser-metal ablation in atmosphere: Initial plasma during laser pulse and further expansion

    SciTech Connect (OSTI)

    Wu, Jian; Wei, Wenfu; Li, Xingwen; Jia, Shenli; Qiu, Aici [State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Shaanxi 710049 (China)] [State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Shaanxi 710049 (China)

    2013-04-22T23:59:59.000Z

    We have investigated the dynamics of the nanosecond laser ablated plasma within and after the laser pulse irradiation using fast photography. A 1064 nm, 15 ns laser beam was focused onto a target made from various materials with an energy density in the order of J/mm{sup 2} in atmosphere. The plasma dynamics during the nanosecond laser pulse were observed, which could be divided into three stages: fast expansion, division into the primary plasma and the front plasma, and stagnation. After the laser terminated, a critical moment when the primary plasma expansion transited from the shock model to the drag model was resolved, and this phenomenon could be understood in terms of interactions between the primary and the front plasmas.

  1. Structural information extracted from the diffraction of XFEL fs-pulses in a crystal

    E-Print Network [OSTI]

    Leonov, A; Benediktovitch, A; Feranchuk, I; Pietsch, U

    2015-01-01T23:59:59.000Z

    We present a theoretical justification for a method of extracting of supplementary information for the phase retrieval procedure taken from diffraction of fs-pulses from X-ray Free Electron Laser facilities. The approach is based on numerical simulation of the dynamics of the electron density in the crystal composed of different atoms in the unit cell, namely a bi-atomic crystal containing heavy and light atoms. It is shown that evaluation of diffraction intensities measured by means of different values of XFEL pulse parameters enables to find absolute values of structure factors for both types of atoms and their relative phase. The accuracy of structural information is discussed in terms of fluctuations of the evaluated atomic scattering factors. Our approach could be important for improvement of phase retrieval methods with respect to a more efficient determination of atomic positions within the unit cell of macromolecules.

  2. Pulsed-electron-beam melting of Fe

    SciTech Connect (OSTI)

    Knapp, J.A.; Follstaedt, D.M.

    1981-01-01T23:59:59.000Z

    Pulsed (50 nsec) electron beams with deposited energies of 1.1 to 2.3 J/cm/sup 2/ have been used to rapidly melt a surface layer of Fe. Calculations show that this range of energies produces melt depths from 0.4 to 1.2 ..mu..m and melt times of 100 to 500 nsec. Optical microscopy and SEM of pulse treated polycrystalline foils show slip traces, as well as a general smoothing of surface features which shows that melting has occurred. TEM shows that the resolidified material is bcc, and that the material within a grain is epitaxial with the substrate. TEM also shows slip traces along (110) planes, as well as a high density of dislocations, both extended and loop. At the highest energy, subgrain boundaries are observed. Some samples were implanted with 1 x 10/sup 16/ Sn/cm/sup 2/ at 150 keV. After pulse treatment, the Sn depth profile was observed to have broadened, consistent with liquid phase diffusion. The Sn had the unexpected effect of suppressing slip at the sample surface.

  3. Oscillating plasma bubbles. II. Pulsed experiments

    SciTech Connect (OSTI)

    Stenzel, R. L.; Urrutia, J. M. [Department of Physics and Astronomy, University of California, Los Angeles, California 90095-1547 (United States)

    2012-08-15T23:59:59.000Z

    Time-dependent phenomena have been investigated in plasma bubbles which are created by inserting spherical grids into an ambient plasma and letting electrons and ions form a plasma of different parameters than the ambient one. There are no plasma sources inside the bubble. The grid bias controls the particle flux. There are sheaths on both sides of the grid, each of which passes particle flows in both directions. The inner sheath or plasma potential develops self consistently to establish charge neutrality and divergence free charge and mass flows. When the electron supply is restricted, the inner sheath exhibits oscillations near the ion plasma frequency. When all electrons are excluded, a virtual anode forms on the inside sheath, reflects all ions such that the bubble is empty. By pulsing the ambient plasma, the lifetime of the bubble plasma has been measured. In an afterglow, plasma electrons are trapped inside the bubble and the bubble decays as slow as the ambient plasma. Pulsing the grid voltage yields the time scale for filling and emptying the bubble. Probes have been shown to modify the plasma potential. Using pulsed probes, transient ringing on the time scale of ion transit times through the bubble has been observed. The start of sheath oscillations has been investigated. The instability mechanism has been qualitatively explained. The dependence of the oscillation frequency on electrons in the sheath has been clarified.

  4. Pulsed Power Peer Review Committee Report

    SciTech Connect (OSTI)

    BLOOMQUIST,DOUGLAS D.

    2000-12-01T23:59:59.000Z

    In 1993, the Government Performance and Results Act (GPRA, PL 103-62) was enacted. GPRA, which applies to all federal programs, has three components: strategic plans, annual performance plans, and metrics to show how well annual plans are being followed. As part of meeting the GRPA requirement in FY2000, a 14-member external peer review panel (the Garwin Committee) was convened on May 17-19, 2000 to review Sandia National Laboratories' Pulsed Power Programs as a component of the Performance Appraisal Process negotiated with the Department of Energy (DOE). The scope of the review included activities in inertial confinement fission (ICF), weapon physics, development of radiation sources for weapons effects simulation, x-ray radiography, basic research in high energy density physics (HEDP), and pulsed power technology research and development. In his charge to the committee, Jeffrey Quintenz, Director of Pulsed Power Sciences (1600) asked that the review be based on four criteria (1) quality of science, technology, and engineering, (2) programmatic performance, management, and planning, (3) relevance to national needs and agency missions, and (4) performance in the operation and construction of major research facilities. In addition, specific programmatic questions were posed by the director and by the DOE-Defense Programs (DP). The accompanying report, produced as a SAND document, is the report of the committee's findings.

  5. New organic crystals for pulse shape discrimination

    SciTech Connect (OSTI)

    Hull, G; Zaitseva, N; Cherepy, N; Newby, J; Stoeffl, W; Payne, S

    2008-07-16T23:59:59.000Z

    Efficient, readily-available, low-cost, high-energy neutron detectors can play a central role in detecting illicit nuclear weapons since neutrons are a strong indication for the presence of fissile material such as Plutonium and Highly-Enriched Uranium. The main challenge in detecting fast neutrons consists in the discrimination of the signal from the gamma radiation background. At present, the only well-investigated organic crystal scintillator for fast neutron detection, in a n/{gamma} mixed field, is stilbene, which while offering good pulse shape discrimination, is not widely used because of its limited availability and high cost. In this work we report the results of our studies made with a number of new organic crystals, which exhibit pulse shape discrimination for detection of fast neutrons. In particular 1,1,4,4-tetraphenyl-1,3-butadiene features a light yield higher than anthracene and a Figure of Merit (FOM) for the pulse shape discrimination better than stilbene. New crystals are good candidates for the low-cost solution growth method, thus representing promising organic scintillators for widespread deployment for high-energy neutron detection.

  6. H-mode fueling optimization with the supersonic deuterium jet in NSTX

    SciTech Connect (OSTI)

    Soukhanovskii, V A; Bell, M G; Bell, R E; Gates, D A; Kaita, R; Kugel, H W; LeBlanc, B P; Lundberg, D P; Maingi, R; Menard, J E; Raman, R; Roquemore, A L; Stotler, D P

    2008-06-18T23:59:59.000Z

    High-performance, long-pulse 0.7-1.2 MA 6-7 MW NBI-heated small-ELM H-mode plasma discharges are developed in the National Spherical Torus Experiment (NSTX) as prototypes for confinement and current drive extrapolations to future spherical tori. It is envisioned that innovative lithium coating techniques for H-mode density pumping and a supersonic deuterium jet for plasma refueling will be used to achieve the low pedestal collisionality and low n{sub e}/n{sub G} fractions (0.3-0.6), both of which being essential conditions for maximizing the non-inductive (bootstrap and beam driven) current fractions. The low field side supersonic gas injector (SGI) on NSTX consists of a small converging-diverging graphite Laval nozzle and a piezoelectric gas valve. The nozzle is capable of producing a deuterium jet with Mach number M {le} 4, estimated gas density at the nozzle exit n {le} 5 x 10{sup 23} m{sup -3}, estimated temperature T {ge} 70 K, and flow velocity v = 2:4 km/s. The nozzle Reynolds number Reis {approx_equal} 6000. The nozzle and the valve are enclosed in a protective carbon fiber composite shroud and mounted on a movable probe at a midplane port location. Despite the beneficial L-mode fueling experience with supersonic jets in limiter tokamaks, there is a limited experience with fueling of high-performance H-mode divertor discharges and the associated density, MHD stability, and MARFE limits. In initial supersonic deuterium jet fueling experiments in NSTX, a reliable H-mode access, a low NBI power threshold, P{sub LH} {le} 2 MW, and a high fueling efficiency (0.1-0.4) have been demonstrated. Progress has also been made toward a better control of the injected fueling gas by decreasing the uncontrolled high field side (HFS) injector fueling rate by up to 95 % and complementing it with the supersonic jet fueling. These results motivated recent upgrades to the SGI gas delivery and control systems. The new SGI-Upgrade (SGI-U) capabilities include multi-pulse ms-scale controls and a reservoir gas pressure up to P{sub 0} = 5000 Torr. In this paper we summarize recent progress toward optimization of H-mode fueling in NSTX using the SGI-U.

  7. Analysis of microwave leaky modes propagating through laser plasma filaments column waveguide

    SciTech Connect (OSTI)

    Alshershby, Mostafa; Hao Zuoqiang; Lin Jingquan [School of Science, Changchun University of Science and Technology, Changchun 130022 (China)

    2012-12-15T23:59:59.000Z

    A plasma column waveguide formed by a bundle of closely spaced plasma filaments induced by the propagation of ultrafast laser pulses in air and revived by a longer infrared laser pulse is shown to support microwave radiation. We consider values of both the plasma electron density and microwave frequency for which the refractive index of plasma is lower than the refractive index of air; therefore, a leaky plasma waveguide can be realized in extremely high frequency band. The guiding mechanism does not require high conductance of the plasma and can be easily excited by using commercial femtosecond laser sources. A theoretical study of leaky mode characteristics of isotropic and homogeneous plasma column waveguides is investigated with several values of plasma and waveguide structure parameters. The microwave transmission loss was found to be mainly caused by the microwave leakage through the air-plasma interface and is weakly dependent on the plasma absorption. In spite of losses of microwaves caused by leakage and plasma absorption, it is shown to be much lower than both that accompanying to surface waves attaching to single conducting plasma wire and the free space propagation over distances in the order of the filament length, which opens exciting perspectives for short distance point to point wireless transmission of pulsed-modulated microwaves.

  8. Long-term environmental stewardship.

    SciTech Connect (OSTI)

    Nagy, Michael David

    2010-08-01T23:59:59.000Z

    The purpose of this Supplemental Information Source Document is to effectively describe Long-Term Environmental Stewardship (LTES) at Sandia National Laboratories/New Mexico (SNL/NM). More specifically, this document describes the LTES and Long-Term Stewardship (LTS) Programs, distinguishes between the LTES and LTS Programs, and summarizes the current status of the Environmental Restoration (ER) Project.

  9. Simulation of ultraviolet- and soft X-ray-pulse generation as a result of cooperative recombination of excitons in diamond nanocrystals embedded in a polymer film

    SciTech Connect (OSTI)

    Kukushkin, V. A., E-mail: vakuk@appl.sci-nnov.ru [Russian Academy of Sciences, Institute for Applied Physics (Russian Federation)

    2013-11-15T23:59:59.000Z

    Using numerical simulation, it is shown that the recombination of free excitons photoexcited in diamond nanocrystals embedded in a polymer film can occur in the cooperative mode. It is found that this mode can be implemented despite the fact that diamond is an 'indirect' semiconductor. It is shown that the power of the generated radiation at the pulse peak during the cooperative recombination of free excitons can exceed that of the incoherent spontaneous emission of the same initial number of free excitons by more than an order of magnitude. Finally, it is shown that the process under consideration can be used to generate picosecond pulses of ultraviolet and soft X-ray electromagnetic field at a wavelength of 235 nm.

  10. PLASTIC DEFORMATIONPLASTIC DEFORMATION Modes of Deformation

    E-Print Network [OSTI]

    Subramaniam, Anandh

    PLASTIC DEFORMATIONPLASTIC DEFORMATION Modes of Deformation The Uniaxial Tension Test Mechanisms underlying Plastic Deformation Strengthening mechanisms Mechanical Metallurgy George E Dieter McClick here to know about all the mechanisms by which materials fail #12;Slip (Dislocation motion) Plastic

  11. Introduction to Scanning Microwave Microscopy Mode

    E-Print Network [OSTI]

    Anlage, Steven

    Wenhai Han Introduction to Scanning Microwave Microscopy Mode Application Note Introduction Mapping through" and meanwhile achieve sufficient sensitivity and resolution. With the invention of scanning been developed to probe materials properties. These include scanning near-field to scanning microwave

  12. Whispering-gallery-mode-based seismometer

    SciTech Connect (OSTI)

    Fourguette, Dominique Claire; Otugen, M Volkan; Larocque, Liane Marie; Ritter, Greg Aan; Meeusen, Jason Jeffrey; Ioppolo, Tindaro

    2014-06-03T23:59:59.000Z

    A whispering-gallery-mode-based seismometer provides for receiving laser light into an optical fiber, operatively coupling the laser light from the optical fiber into a whispering-gallery-mode-based optical resonator, operatively coupling a spring of a spring-mass assembly to a housing structure; and locating the whispering-gallery-mode-based optical resonator between the spring-mass assembly and the housing structure so as to provide for compressing the whispering-gallery-mode-based optical resonator between the spring-mass assembly and the housing structure responsive to a dynamic compression force from the spring-mass assembly responsive to a motion of the housing structure relative to an inertial frame of reference.

  13. Quantum Simulation of Spin Chains Coupled to Bosonic Modes with Superconducting Circuits

    E-Print Network [OSTI]

    U. Las Heras; L. García-Álvarez; A. Mezzacapo; E. Solano; L. Lamata

    2015-07-13T23:59:59.000Z

    We propose the implementation of a digital quantum simulation of spin chains coupled to bosonic field modes in superconducting circuits. Gates with high fidelities allows one to simulate a variety of Ising magnetic pairing interactions with transverse field, Tavis-Cummings interaction between spins and a bosonic mode, and a spin model with three-body terms. We analyze the feasibility of the implementation in realistic circuit quantum electrodynamics setups, where the interactions are either realized via capacitive couplings or mediated by microwave resonators.

  14. Quantum Simulation of Spin Chains Coupled to Bosonic Modes with Superconducting Circuits

    E-Print Network [OSTI]

    U. Las Heras; L. García-Álvarez; A. Mezzacapo; E. Solano; L. Lamata

    2015-07-09T23:59:59.000Z

    We propose the implementation of a digital quantum simulation of spin chains coupled to bosonic field modes in superconducting circuits. Gates with high fidelities allows one to simulate a variety of Ising magnetic pairing interactions with transverse field, Tavis-Cummings interaction between spins and a bosonic mode, and a spin model with three-body terms. We analyze the feasibility of the implementation in realistic circuit quantum electrodynamics setups, where the interactions are either realized via capacitive couplings or mediated by microwave resonators.

  15. Optical emission characteristics of surface nanosecond pulsed dielectric barrier discharge plasma

    SciTech Connect (OSTI)

    Wu Yun; Li Yinghong; Jia Min; Song Huimin; Liang Hua [Science and Technology on Plasma Dynamics Lab, Aeronautics and Astronautics Engineering College, Air Force Engineering University, Xi'an 710038 (China)

    2013-01-21T23:59:59.000Z

    This paper reports an experimental study of the optical emission characteristics of the surface dielectric barrier discharge plasma excited by nanosecond pulsed voltage. N{sub 2}(C{sup 3}{Pi}{sub u}) rotational and vibrational temperatures are almost the same with upper electrode powered with positive polarity and lower electrode grounded or upper electrode grounded and lower electrode powered with positive polarity. While the electron temperature is 12% higher with upper electrode powered with positive polarity and lower electrode grounded. When the frequency is below 2000 Hz, there is almost no influence of applied voltage amplitude and frequency on N{sub 2}(C{sup 3}{Pi}{sub u}) rotational, vibrational temperature and electron temperature. As the pressure decreases from 760 Torr to 5 Torr, N{sub 2}(C{sup 3}{Pi}{sub u}) rotational temperature remains almost unchanged, while its vibrational temperature decreases initially and then increases. The discharge mode changes from a filamentary type to a glow type around 80 Torr. In the filamentary mode, the electron temperature remains almost unchanged. In the glow mode, the electron temperature increases while the pressure decreases.

  16. Electrostatic mode associated with the pinch velocity in reversed field pinch simulations

    SciTech Connect (OSTI)

    Delzanno, Gian Luca [Los Alamos National Laboratory (LANL); Chacon, Luis [Oak Ridge National Laboratory (ORNL); Finn, John M. [Los Alamos National Laboratory (LANL)

    2008-01-01T23:59:59.000Z

    The existence of a new phenomenon in reversed field pinch (RFP) simulations related to the equilibrium pinch flow is discussed. This behavior is due to the inward equilibrium flow, but is strongly affected by boundary conditions on the perturbed azimuthal flow. It is important to understand and control this mechanism in single helicity simulations of RFPs. This mechanism can be explained in terms of an electrostatic instability related to a mode which can occur in fluid dynamics. In a simple linear model, it is shown that the mode, which is related to the inward advection of angular momentum from the edge, can be stabilized by using homogeneous Dirichlet (no-slip) boundary conditions at the wall. Behavior due to this mode is present in nonlinear simulations with zero-viscous-stress boundary conditions on the tangential velocity at the wall and, even in the presence of the usual magnetohydrodynamic modes, this mode can dominate the nonlinear dynamics of the velocity. In nonlinear simulations with Dirichlet boundary conditions on the tangential velocity, behavior associated with this electrostatic mode is not observed.

  17. Electrostatic mode associated with the pinch velocity in reversed field pinch simulations

    SciTech Connect (OSTI)

    Delzanno, Gian Luca; Finn, John M. [T-15 Plasma Theory Group, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Chacon, Luis [T-15 Plasma Theory Group, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Fusion Energy Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830 (United States)

    2008-12-15T23:59:59.000Z

    The existence of a new phenomenon in reversed field pinch (RFP) simulations related to the equilibrium pinch flow is discussed. This behavior is due to the inward equilibrium flow, but is strongly affected by boundary conditions on the perturbed azimuthal flow. It is important to understand and control this mechanism in single helicity simulations of RFPs. This mechanism can be explained in terms of an electrostatic instability related to a mode which can occur in fluid dynamics. In a simple linear model, it is shown that the mode, which is related to the inward advection of angular momentum from the edge, can be stabilized by using homogeneous Dirichlet (no-slip) boundary conditions at the wall. Behavior due to this mode is present in nonlinear simulations with zero-viscous-stress boundary conditions on the tangential velocity at the wall and, even in the presence of the usual magnetohydrodynamic modes, this mode can dominate the nonlinear dynamics of the velocity. In nonlinear simulations with Dirichlet boundary conditions on the tangential velocity, behavior associated with this electrostatic mode is not observed.

  18. Relativistic Single-Cycled Short-Wavelength Laser Pulse Compressed from a Chirped Pulse Induced by Laser-Foil Interaction

    SciTech Connect (OSTI)

    Ji, L. L.; Shen, B. F.; Li, D. X.; Wang, D.; Leng, Y. X.; Zhang, X. M.; Wen, M.; Wang, W. P.; Xu, J. C.; Yu, Y. H. [State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, P.O. Box 800-211, Shanghai 201800 (China)

    2010-07-09T23:59:59.000Z

    By particle-in-cell simulation and analysis, we propose a plasma approach to generate a relativistic chirped pulse based on a laser-foil interaction. When two counterpropagating circularly polarized pulses interact with an overdense foil, the driving pulse (with a larger laser field amplitude) will accelerate the whole foil to form a double-layer structure, and the scattered pulse (with a smaller laser field amplitude) is reflected by this flying layer. Because of the Doppler effect and the varying velocity of the layer, the reflected pulse is up-shifted for frequency and chirped; thus, it could be compressed to a nearly single-cycled relativistic laser pulse with a short wavelength. Simulations show that a nearly single-cycled subfemtosecond relativistic pulse can be generated with a wavelength of 0.2 {mu}m after dispersion compensation.

  19. Electromagnetic effects on geodesic acoustic modes

    SciTech Connect (OSTI)

    Bashir, M. F., E-mail: frazbashir@yahoo.com [Salam Chair in Physics, G. C. University Lahore, Katchery Road, Lahore 54000 (Pakistan); Department of Physics, G. C. University Lahore, Katchery Road, Lahore 54000 (Pakistan); Smolyakov, A. I. [University of Saskatchewan, 116 Science Place, Saskatoon S7N 5E2 (Canada); Institute of Tokamak Physics, NRC “Kurchatov Institute,” 123182 Moscow (Russian Federation); Elfimov, A. G. [Institute of Physics, University of São Paulo, São Paulo 05508-090 (Brazil); Melnikov, A. V. [Institute of Tokamak Physics, NRC “Kurchatov Institute,” 123182 Moscow (Russian Federation); National Research Nuclear University MEPhI, 115409, Moscow (Russian Federation); Murtaza, G. [Visiting Professor, Department of Physics, Quaid-e-Azam University, Islamabad (Pakistan)

    2014-08-15T23:59:59.000Z

    By using the full electromagnetic drift kinetic equations for electrons and ions, the general dispersion relation for geodesic acoustic modes (GAMs) is derived incorporating the electromagnetic effects. It is shown that m?=?1 harmonic of the GAM mode has a finite electromagnetic component. The electromagnetic corrections appear for finite values of the radial wave numbers and modify the GAM frequency. The effects of plasma pressure ?{sub e}, the safety factor q, and the temperature ratio ? on GAM dispersion are analyzed.

  20. Propagation Plane waves -High order Modes

    E-Print Network [OSTI]

    Berlin,Technische Universität

    1 Propagation · Plane waves - High order Modes y x a One wave: p(x,y,t)=p0 cos(k y)e-jk x e j t vy(y,t)= 0 ; y=0,a xy } ky = n a Propagation · Plane waves - High order Modes x n a p(x,y,t)=pn cos( y + - +- + + - +- + - + + +- - - (m,n) #12;4 Propagation · Circular duct ­ Helical waves (spiralling waves) kc=m/a kz k