Science.gov

Sample records for 1-ma 100-ns rise-time

  1. Implosion dynamics and radiation features of planar, compact cylindrical, and nested wire arrays on 1 MA, 100 ns z-pinch generators

    NASA Astrophysics Data System (ADS)

    Kantsyrev, V. L.; Safronova, A. S.; Esaulov, A. A.; Williamson, K.; Shrestha, I.; Osborne, G.; Ouart, N. D.; Yilmaz, M. F.; Shlyaptseva, V.; Greenly, J. B.; Douglass, J. D.; McBride, R. D.; Chalenski, D. A.; Hammer, D. A.; Kusse, B. R.; Rudakov, L. I.; Chuvatin, A. S.

    2007-11-01

    Plasma formation and implosion features of planar wire arrays (PWA), compact cylindrical wire arrays (CWA), and low-wire number nested wire arrays (NWA) of the small size (6-15 mm) were studied on the 1 MA, 100 ns UNR Zebra and Cornell COBRA generators. The powers and yields were maximum for Mo double PWA, followed by W compact CWA and PWA, Mo single PWA and compact CWA, stainless steel (SS304) and Al compact CWAs, and Al/SS304 and SS304/SS304 NWAs. Despite different implosion dynamics of PWAs and compact CWAs they formed plasma that radiated similar yields and powers. The possibility of radiation pulse shaping by varying geometry and materials of PWAs and NWAs will be discussed. Simulations with Wire Dynamics Model and 2D MHD model with enhanced resistivity will be presented. Work was supported by DOE/NNSA under Coop. Agr. DE-FC52-06NA27586, DE-FC52-06NA27588, DE-F03-02NA00057, and in part by DE-FC52 06NA27616.

  2. Amplitude- and rise-time-compensated filters

    DOEpatents

    Nowlin, Charles H.

    1984-01-01

    An amplitude-compensated rise-time-compensated filter for a pulse time-of-occurrence (TOOC) measurement system is disclosed. The filter converts an input pulse, having the characteristics of random amplitudes and random, non-zero rise times, to a bipolar output pulse wherein the output pulse has a zero-crossing time that is independent of the rise time and amplitude of the input pulse. The filter differentiates the input pulse, along the linear leading edge of the input pulse, and subtracts therefrom a pulse fractionally proportional to the input pulse. The filter of the present invention can use discrete circuit components and avoids the use of delay lines.

  3. Short rise time intense electron beam generator

    DOEpatents

    Olson, Craig L.

    1987-01-01

    A generator for producing an intense relativistic electron beam having a subnanosecond current rise time includes a conventional generator of intense relativistic electrons feeding into a short electrically conductive drift tube including a cavity containing a working gas at a low enough pressure to prevent the input beam from significantly ionizing the working gas. Ionizing means such as a laser simultaneously ionize the entire volume of working gas in the cavity to generate an output beam having a rise time less than one nanosecond.

  4. Short rise time intense electron beam generator

    DOEpatents

    Olson, C.L.

    1984-03-16

    A generator for producing an intense relativisitc electron beam having a subnanosecond current rise time includes a conventional generator of intense relativistic electrons feeding into a short electrically conductive drift tube including a cavity containing a working gas at a low enough pressure to prevent the input beam from significantly ionizing the working gas. Ionizing means such as a laser simultaneously ionize the entire volume of working gas in the cavity to generate an output beam having a rise time less than one nanosecond.

  5. Plasma Density and Magnetic Field Evolution in a 100-ns Plasma Opening Switch

    NASA Astrophysics Data System (ADS)

    Weingarten, A.; Maron, Y.; Krasik, Ya. E.; Weber, B. V.; Commisso, R. J.

    1997-11-01

    The electron density and magnetic field evolution in a 100-ns, 170-kA POS are investigated using emission spectroscopy. The plasma is doped by various elements using laser evaporation in order to obtain spatially resolved measurements. The prefilled plasma density, determined from Stark broadening and ionization times, is 1-2× 10^14 cm-3. The opening time was observed to depend on the prefilled plasma azimuthal uniformity. During the pulse, the plasma density drops substantially during 10-20 ns. The drop propagates mainly axially from the plasma generator side to the load side at a velocity of ≈ 2 × 10^8 cm/s. The drop is accompanied by penetration of the magnetic field, determined from the Zeeman effect. A mapping of the density and the magnetic field distributions in the r-z plane will be presented. Proton motion is probably important, but the axial velocities of heavy ions are low (≈ 10^6 cm/s << V_Alfven). These results will be compared with previous results obtained on Gamble I(B. V. Weber et. al.), Appl. Physc. Lett. 45, 1043, (1984).

  6. MAIZE: a 1 MA LTD-Driven Z-Pinch at The University of Michigan

    SciTech Connect

    Gilgenbach, R. M.; Gomez, M. R.; Zier, J. C.; Tang, W. W.; French, D. M.; Lau, Y. Y.; Mazarakis, M. G.; Cuneo, M. E.; Johnston, M. D.; Oliver, B. V.; Mehlhorn, T. A.; Kim, A. A.; Sinebryukhov, V. A.

    2009-01-21

    Researchers at The University of Michigan have constructed and tested a 1-MA Linear Transformer Driver (LTD), the first of its type to reach the USA. The Michigan Accelerator for Inductive Z-pinch Experiments, (MAIZE), is based on the LTD developed at the Institute of High Current Electronics in collaboration with Sandia National Labs and UM. This LTD utilizes 80 capacitors and 40 spark gap switches, arranged in 40 'bricks,' to deliver a 1 MA, 100 kV pulse with 100 ns risetime into a matched resistive load. Preliminary resistive-load test results are presented for the LTD facility.Planned experimental research programs at UM include: a) Studies of Magneto-Raleigh-Taylor instability of planar foils, and b) Vacuum convolute studies including cathode and anode plasma.

  7. Fast rise-time, fiber optic pin

    SciTech Connect

    Roeske, F

    1998-05-12

    A reliable, simple fast-rise-time diagnostic has been developed for measuring the breakout time of the detonation wave in a detonating high explosive. The intrinsic rise time of the signals generated is less than one nanosecond. The technique, called FAT (Fiber Arrival Time), consists of an optical fiber with one end coated with ~1500 Å Aluminum. The coated end is placed in intimate contact with the surface of the explosive. The detonation wave interacting with the Al surface causes a prompt flash of light which is recorded at the output end of the fiber. The active area of the FAT probe end is 100 µm in diameter and centered to within ±10 µm also giving excellent spatial precision. When used in this mode, FAT overcomes difficulties of electronic and past fiber optic pins. When looking at a flyer plate arrival the time response appears to be a function of the metal plate velocity.

  8. Low-noise detector and amplifier design for 100 ns direct detection CO{sub 2} LIDAR receiver

    SciTech Connect

    Cafferty, M.M.; Cooke, B.J.; Laubscher, B.E.; Olivas, N.L.; Fuller, K.

    1997-06-01

    The development and test results of a prototype detector/amplifier design for a background limited, pulsed 100 ns, 10--100 kHz repetition rate LIDAR/DIAL receiver system are presented. Design objectives include near-matched filter detection of received pulse amplitude and round trip time-of-flight, and the elimination of excess correlated detector/amplifier noise for optimal pulse averaging. A novel pole-zero cancellation amplifier, coupled with a state-of-the-art SBRC (Santa Barbara Research Center) infrared detector was implemented to meet design objectives. The pole-zero cancellation amplifier utilizes a tunable, pseudo-matched filter technique to match the width of the laser pulse to the shaping time of the filter for optimal SNR performance. Low frequency correlated noise, (l/f and drift noise) is rejected through a second order high gain feedback loop. The amplifier also employs an active detector bias stage minimizing detector drift. Experimental results will be provided that demonstrate near-background limited, 100 ns pulse detection performance given a 8.5--11.5 {micro}m (300 K B.B.) radiant background, with the total noise floor spectrally white for optimal pulse averaging efficiency.

  9. Mapping Rise Time Information with Down-Shift Analysis

    SciTech Connect

    Tunnell, T. W., Machorro, E. A., Diaz, A. B.

    2011-11-01

    These viewgraphs summarize the application of recent developments in digital down-shift (DDS) analysis of up converted PDV data to map out how well the PDV diagnostic would capture rise time information (mid point and rise time) in short rise time (<1 ns) shock events. The mapping supports a PDV vs VISAR challenge. The analysis concepts are new (~September FY 2011), simple, and run quickly, which makes them good tools to map out (with ~1 million Monte Carlo simulations) how well PDV captures rise time information as function of baseline velocity, rise time, velocity jump, and signal-to-noise ratios.

  10. Aluminum and tungsten X-pinch experiments on 100 kA, 100 ns linear transformer driver stage

    SciTech Connect

    Wu Jian; Sun Tieping; Wu Gang; Wang Liangping; Han Juanjuan; Li Mo; Cong Peitian; Qiu Aici; Lv Min

    2011-05-15

    X-pinch experiments have been carried out on a 100 kA, 100 ns linear transformer driver stage recently built up. The X-pinches exhibited a source size of about 10 {mu}m, a pulse duration of 3 ns, 3-5 keV radiation energy of 3.9 mJ, and a burst time jitter of tens of nanosecond with the 2-wire 8 {mu}m W X-pinch load. The generator output current and the X-pinch characteristics depended on the X-pinch wire materials in the tests. X-ray backlighting images from the insects showed the significant phase-contrast effect.

  11. Measurements of plasma conditions in precursor plasmas at the 1-MA Zebra facility

    NASA Astrophysics Data System (ADS)

    Ouart, N. D.; Coverdale, C. A.; Safronova, A. S.; Kantsyrev, V. L.; Williamson, K. M.; Shrestha, I.; Osborne, G. C.; Deeney, C.

    2007-11-01

    Precursor plasmas, both the early time precursor flow of mass and the accumulation of this material on axis, were observed on many z-pinch experiments at various facilities, including low current (< 1MA) and high current (>15 MA, Z) facilities. The impact of these precursors on stagnated plasmas, and targets such as those used for ICF experiments, is still under evaluation. Experiments were performed at the UNR 1-MA, 100ns Zebra facility to study these precursor plasmas with Cu wire arrays. Significant precursor radiation at photon energies > 1 keV was observed on filtered PCDs. Te and ne of the precursor radiation were obtained from modeling of time-resolved spectroscopy of the Cu L-shell emissions for 6 wires on 12mm diameter loads. The precursor plasma temperatures are consistently >250eV. Time resolved pinhole images were also collected, which show bright spots of radiation along the axial length of the pinch. Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the US DOE under Contract DE-AC04-94AL85000. Work was also supported by the DOE/NNSA Coop. agr. DE-FC52-06NA27616, 06NA27588, 06NA27586, and by fellowship from the NPSC with SNL.

  12. Fast rise times and the physical mechanism of deep earthquakes

    NASA Technical Reports Server (NTRS)

    Houston, H.; Williams, Q.

    1991-01-01

    A systematic global survey of the rise times and stress drops of deep and intermediate earthquakes is reported. When the rise times are scaled to the seismic moment release of the events, their average is nearly twice as fast for events deeper than about 450 km as for shallower events.

  13. Effect of Current Rise-time on the Formation of Precursor Structures and Mass Ablation Rate in Cylindrical Wire Array Z-Pinches

    SciTech Connect

    Bott, S. C.; Eshaq, Y.; Ueda, U.; Haas, D. M.; Beg, F. N.; Hammer, D. A.; Kusse, B.; Greenly, J.; Shelkovenko, T. A.; Pikuz, S. A.; Blesener, I. C.; McBride, R. D.; Douglass, J. D.; Bell, K.; Knapp, P.; Chittenden, J. P.; Lebedev, S. V.; Bland, S. N.; Hall, G. N.; Suzuki, F. A.

    2009-01-21

    We present the first study to directly compare the mass ablation rates of cylindrical wire arrays as a function of the current rise-rate. Formation of the precursor column is investigated on both the MAPGIE (1 MA, 250 ns) and COBRA (1 MA, 100 ns) generators, and results are used to infer the change in the mass ablation rate induced by the rise-rate of the drive current. Laser shadowography, gated XUV imaging and x-ray diodes are used to compare the dynamical behavior both generators, and x-pinch radiography and XUV spectroscopy and provide density evolution and temperature measurements respectively. Results are compared to predictions from an analytical scaling model based on a fixed ablation rate, and the close correlation achieved suggests that the effective ablation velocity is not a strong function of the current rise rate.

  14. An evaluation of rise time characterization and prediction methods

    NASA Technical Reports Server (NTRS)

    Robinson, Leick D.

    1994-01-01

    One common method of extrapolating sonic boom waveforms from aircraft to ground is to calculate the nonlinear distortion, and then add a rise time to each shock by a simple empirical rule. One common rule is the '3 over P' rule which calculates the rise time in milliseconds as three divided by the shock amplitude in psf. This rule was compared with the results of ZEPHYRUS, a comprehensive algorithm which calculates sonic boom propagation and extrapolation with the combined effects of nonlinearity, attenuation, dispersion, geometric spreading, and refraction in a stratified atmosphere. It is shown there that the simple empirical rule considerably overestimates the rise time estimate. In addition, the empirical rule does not account for variations in the rise time due to humidity variation or propagation history. It is also demonstrated that the rise time is only an approximate indicator of perceived loudness. Three waveforms with identical characteristics (shock placement, amplitude, and rise time), but with different shock shapes, are shown to give different calculated loudness. This paper is based in part on work performed at the Applied Research Laboratories, the University of Texas at Austin, and supported by NASA Langley.

  15. Study of the time-resolved, 3-dimensional current density distribution in solid metallic liners at 1 MA

    NASA Astrophysics Data System (ADS)

    Bott-Suzuki, S. C.; Cordaro, S. W.; Caballero Bendixsen, L. S.; Atoyan, L.; Byvank, T.; Potter, W.; Kusse, B. R.; Greenly, J. B.; Hammer, D. A.

    2016-09-01

    We present a study of the time varying current density distribution in solid metallic liner experiments at the 1 MA level. Measurements are taken using an array of magnetic field probes which provide 2D triangulation of the average centroid of the drive current in the load at 3 discrete axial positions. These data are correlated with gated optical self-emission imaging which directly images the breakdown and plasma formation region. Results show that the current density is azimuthally non-uniform and changes significantly throughout the 100 ns experimental timescale. Magnetic field probes show clearly motion of the current density around the liner azimuth over 10 ns timescales. If breakdown is initiated at one azimuthal location, the current density remains non-uniform even over large spatial extents throughout the current drive. The evolution timescales are suggestive of a resistive diffusion process or uneven current distributions among simultaneously formed but discrete plasma conduction paths.

  16. Rise time measurement for ultrafast X-ray pulses

    DOEpatents

    Celliers, Peter M.; Weber, Franz A.; Moon, Stephen J.

    2005-04-05

    A pump-probe scheme measures the rise time of ultrafast x-ray pulses. Conventional high speed x-ray diagnostics (x-ray streak cameras, PIN diodes, diamond PCD devices) do not provide sufficient time resolution to resolve rise times of x-ray pulses on the order of 50 fs or less as they are being produced by modern fast x-ray sources. Here, we are describing a pump-probe technique that can be employed to measure events where detector resolution is insufficient to resolve the event. The scheme utilizes a diamond plate as an x-ray transducer and a p-polarized probe beam.

  17. Rise Time Measurement for Ultrafast X-Ray Pulses

    DOEpatents

    Celliers, Peter M.; Weber, Franz A.; Moon, Stephen J.

    2005-04-05

    A pump-probe scheme measures the rise time of ultrafast x-ray pulses. Conventional high speed x-ray diagnostics (x-ray streak cameras, PIN diodes, diamond PCD devices) do not provide sufficient time resolution to resolve rise times of x-ray pulses on the order of 50 fs or less as they are being produced by modern fast x-ray sources. Here, we are describing a pump-probe technique that can be employed to measure events where detector resolution is insufficient to resolve the event. The scheme utilizes a diamond plate as an x-ray transducer and a p-polarized probe beam.

  18. Detection of Sound Rise Time by Adults with Dyslexia

    ERIC Educational Resources Information Center

    Hamalainen, J.; Leppanen, P.H.T.; Torppa, M.; Muller, K.; Lyytinen, H.

    2005-01-01

    Low sensitivity to amplitude modulated (AM) sounds is reported to be associated with dyslexia. An important aspect of amplitude modulation cycles are the rise and fall times within the sound. In this study, simplified stimuli equivalent to just one cycle were used and sensitivity to varying rise times was explored. Adult participants with dyslexia…

  19. The Rise Time of Normal and Subluminous Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    González-Gaitán, S.; Conley, A.; Bianco, F. B.; Howell, D. A.; Sullivan, M.; Perrett, K.; Carlberg, R.; Astier, P.; Balam, D.; Balland, C.; Basa, S.; Fouchez, D.; Fourmanoit, N.; Graham, M. L.; Guy, J.; Hardin, D.; Hook, I. M.; Lidman, C.; Pain, R.; Palanque-Delabrouille, N.; Pritchet, C. J.; Regnault, N.; Rich, J.; Ruhlmann-Kleider, V.

    2012-01-01

    We calculate the average stretch-corrected rise time of Type Ia supernovae (SNe Ia) in the Supernova Legacy Survey. We use the aggregate light curves of spectroscopic and photometrically identified SNe Ia to fit the rising part of the light curve with a simple quadratic model. We obtain a light curve shape corrected, i.e., stretch-corrected, fiducial rise time of 17.02+0.18 - 0.28 (stat) days. The measured rise time differs from an earlier finding by the SNLS (Conley et al.) due to the use of different SN Ia templates. We compare it to nearby samples using the same methods and find no evolution in the early part of the light curve of SNe Ia up to z = 1. We search for variations among different populations, particularly subluminous objects, by dividing the sample in stretch. Bright and slow decliners (s > 1.0) have consistent stretch-corrected rise times compared to fainter and faster decliners (0.8 < s <= 1.0); they are shorter by 0.57+0.47 - 0.50 (stat) days. Subluminous SNe Ia (here defined as objects with s <= 0.8), although less constrained, are also consistent, with a rise time of 18.03+0.81 - 1.37 (stat) days. We study several systematic biases and find that the use of different fiducial templates may affect the average rise time but not the intrinsic differences between populations. Based on our results, we estimate that subluminous SNe Ia are powered by 0.05-0.35 M ⊙ of 56Ni synthesized in the explosion. Our conclusions are the same for the single-stretch and two-stretch parameterizations of the light curve. Based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii (CFHT) which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based in part on data products at the Canadian Astronomy Data Centre as part of the Canada

  20. Neural processing of amplitude and formant rise time in dyslexia.

    PubMed

    Peter, Varghese; Kalashnikova, Marina; Burnham, Denis

    2016-06-01

    This study aimed to investigate how children with dyslexia weight amplitude rise time (ART) and formant rise time (FRT) cues in phonetic discrimination. Passive mismatch responses (MMR) were recorded for a/ba/-/wa/contrast in a multiple deviant odd-ball paradigm to identify the neural response to cue weighting in 17 children with dyslexia and 17 age-matched control children. The deviant stimuli had either partial or full ART or FRT cues. The results showed that ART did not generate an MMR in either group, whereas both partial and full FRT cues generated MMR in control children while only full FRT cues generated MMR in children with dyslexia. These findings suggest that children, both controls and those with dyslexia, discriminate speech based on FRT cues and not ART cues. However, control children have greater sensitivity to FRT cues in speech compared to children with dyslexia.

  1. SNLS: Supernova Rise Times from the SNLS Sample

    NASA Astrophysics Data System (ADS)

    Conley, A.; Howell, D. A.; Howes, A.; Astier, P.; Aubourg, E.; Balam, D.; Basa, S.; Carlberg, R. G.; Fabbro, S.; Fouchez, D.; Guy, J.; Hook, I.; Lafoux, H.; Neill, J. D.; Pain, R.; Palanque-Delabrouille, N.; Perett, K.; Pritchet, C. J.; Regnault, N.; Rich, J.; Sullivan, M.; Taillet, R.; Baumont, S.; Bronder, J.; Lusset, V.; Ripoche, P.; Mourao, A.; Perlmutter, S.; Tao, C.

    2005-12-01

    Type Ia supernovae (SNe Ia) provide the most direct evidence for the acceleration of the Universe. This evidence relies on a comparison between the luminosities of distant and nearby SNe Ia, and hence is potentially sensitive to any evolution in the mean lightcurve properties between these two samples. One method for testing for the presence of such effects is to measure and compare the rise time, which is the time between explosion and maximum luminosity, of the two samples. The Supernova Legacy Survey provides an excellent data sample for the analysis of this issue, since it's 'rolling search' nature yields lightcurves which are well sampled prior to maximum light. Here we discuss measurements of the rise time from SNLS data and what they can tell us about evolutionary effects.

  2. Rise-Time Distortion of Signal without Carrying Signal

    NASA Astrophysics Data System (ADS)

    Bukhman, N. S.

    2016-08-01

    The article deals with one-dimensional problem of rise-time distortion signal without carrying signal, that appears in the starting point intermittently, that is signal distortion at front edge or one of its derivative. The authors show that front edge of signal isn't distorted in case of propagation in unrestricted (including absorbing) area (amplitude of starting signal step or of one of its derivatives doesn't change) and move with the accuracy of vacuum light speed. The paper proves that it is the time interval shortage that causes signal loss with the route extension, but not the reduction of its starting amplitude, during which front edge of signal retains its starting value. The research presents new values for this time interval.

  3. Fast rise time IR detectors for lepton colliders

    NASA Astrophysics Data System (ADS)

    Drago, A.; Bini, S.; Cestelli Guidi, M.; Marcelli, A.; Pace, E.

    2016-07-01

    Diagnostics is a fundamental issue for accelerators whose demands are continuously increasing. In particular bunch-by-bunch diagnostics is a key challenge for the latest generation of lepton colliders and storage rings. The Frascati Φ-factory, DAΦNE, colliding at 1.02 GeV in the centre of mass, hosts in the main rings few synchrotron radiation beamlines and two of them collect the synchrotron radiation infrared emission: SINBAD from the electron ring and 3+L from the positron ring. At DAΦNE each bucket is 2.7 ns long and particles are gathered in bunches emitting pulsed IR radiation, whose intensity in the long wavelength regime is directly proportional to the accumulated particles. Compact uncooled photoconductive HgCdTe detectors have been tested in both beamlines using dedicated optical layouts. Actually, the fast rise time of HgCdTe semiconductors give us the chance to test bunch-by-bunch devices for both longitudinal and transverse diagnostics. For the longitudinal case, single pixel detectors have been used, while for the transverse diagnostics, multi-pixel array detectors, with special custom design, are under test. This contribution will briefly describe the status of the research on fast IR detectors at DAΦNE, the results obtained and possible foreseen developments.

  4. Azimuthal Current Density Distribution Resulting from a Power Feed Vacuum Gap in Metallic Liner Experiments at 1 MA

    NASA Astrophysics Data System (ADS)

    Bott-Suzuki, Simon; Cordaro, S. W.; Caballero Bendixsen, L. S.; Atoyan, L.; Byvank, T.; Potter, W.; Kusse, B. R.; Greenly, J. B.; Hammer, D. A.; Chittenden, J. P.; Jennings, C. A.

    2015-11-01

    We present a study investigating the initiation of plasma in solid, metallic liners where the liner thickness is large compared to the collisionless skin depth. A vacuum gap is introduced in the power feed and we investigate the effect of this on the azimuthal initiation of plasma in the liner. We present optical emission data from aluminum liners on the 1 MA, 100ns COBRA generator. We use radial and axial gated imaging and streak photography, which show a dependence of onset of emission with the size of a small power-feed vacuum gap. The evolution of ``hot-spots'' generated from breakdown vacuum gap evolves relatively slowly and azimuthal uniformity is not observed on the experimental time-scale. We also show measurements of the B-field both outside and inside the liner, using miniature Bdot probes, which show a dependence on the liner diameter and thickness, and a correlation to the details of the breakdown. These data will be compared to magneto-hydrodynamic simulations to infer how such non-uniformities may affect full liner implosion experiments.

  5. Functional Domain Motions in Proteins on the 1 100 ns Timescale: Comparison of Neutron Spin-Echo Spectroscopy of Phosphoglycerate Kinase with Molecular-Dynamics Simulation

    SciTech Connect

    Smolin, Nikolai; Biehl, R; Kneller, Gerald; Richter, Dieter O; Smith, Jeremy C

    2011-01-01

    Protein function often requires large-scale domain motion. An exciting new development in the experimental characterization of domain motions in proteins is the application of neutron spin-echo spectroscopy (NSE). NSE directly probes coherent (i.e., pair correlated) scattering on the 1 100 ns timescale. Here, we report on all-atom molecular-dynamics (MD) simulation of a protein, phosphoglycerate kinase, from which we calculate small-angle neutron scattering (SANS) and NSE scattering properties. The simulation-derived and experimental-solution SANS results are in excellent agreement. The contributions of translational and rotational whole-molecule diffusion to the simulation-derived NSE and potential problems in their estimation are examined. Principal component analysis identifies types of domain motion that dominate the internal motion's contribution to the NSE signal, with the largest being classic hinge bending. The associated free-energy profiles are quasiharmonic and the frictional properties correspond to highly overdamped motion. The amplitudes of the motions derived by MD are smaller than those derived from the experimental analysis, and possible reasons for this difference are discussed. The MD results confirm that a significant component of the NSE arises from internal dynamics. They also demonstrate that the combination of NSE with MD is potentially useful for determining the forms, potentials of mean force, and time dependence of functional domain motions in proteins.

  6. Helical Striation Pattern Generation and Axial Field Compression in Aluminum Liner Experiments at 1 MA

    NASA Astrophysics Data System (ADS)

    Atoyan, Levon; Byvank, Tom; Greenly, John; Kusse, Bruce; Pikuz, Sergei; Potter, William; Shelkovenko, Tania; Hammer, David

    2015-11-01

    Awe et al. [Phys. Plasmas 21, 235005, 2014] found on the 20 MA Z machine that applying an externally generated axial magnetic field to an imploding liner produces a helical plasma pattern near the surface of the liner. Here we show that this phenomenon is also observed using 10 mm long cylindrical metal liners having 16 mm diameter and 3 to 6 μm wall thickness on the 1 MA, 100-200 ns COBRA pulsed power generator [T. A. Shelkovenko et al., Rev. Sci. Instrum. 77, 10F521, 2006]. The magnetic field in these experiments is created using a 150 μs rise time Helmholtz coil, and the pattern is observed using extreme ultraviolet imaging. Moreover, using B-dot probes we show that there is a 4-8% axial magnetic field compression relative to the initially applied Bz. Using a visible light framing camera, we show that this compression begins before the outside surface of the liner has become a visible light emitting plasma. This research was sponsored by the NNSA SSAP under DOE Coop Agreement DE-NA0001836 and DOE grant DE-NA0001847 as well as by NSF grant PHY-1102471.

  7. Planar Foil MRT Instability Measurements Using a 1-MA LTD

    NASA Astrophysics Data System (ADS)

    Zier, J. C.; Chalenski, D. A.; Patel, S. G.; French, D. M.; Gilgenbach, R. M.; Gomez, M. R.; Lau, Y. Y.; Steiner, A. M.; Rittersdorf, I. M.; Weis, M. R.; Mazarakis, M. G.; Lopez, M. R.; Cuneo, M. E.

    2011-10-01

    Initial dynamic load experiments were performed on UM's 1-MA linear transformer driver (LTD) facility, MAIZE, to characterize magneto-Rayleigh-Taylor (MRT) instability growth and plasma dynamics on planar-foil plasmas. The loads utilized a double current return plate geometry with a 400 nm-thick Al foil positioned between the return plates. Magnetic pressure accelerated the foil plasma to drive MRT instability that was measured using shadowgraphy. Plasma dynamics were observed to be dominated by an initial expansion phase where both foil interfaces were found to be MRT unstable with 85-105 ns e-folding times. This research was supported by US DoE award number DE-SC0002590, US DoE through SNL award numbers 240985 and 768225 to UM, and from NSF award number PHY 0903340 to UM. JC Zier and SG Patel were supported by NPSC fellowships through SNL.

  8. A note on some statistical properties of rise time parameters used in muon arrival time measurements

    NASA Technical Reports Server (NTRS)

    Vanderwalt, D. J.; Devilliers, E. J.

    1985-01-01

    Most investigations of the muon arrival time distribution in EAS during the past decade made use of parameters which can collectively be called rise time parameters. The rise time parameter T sub A/B is defined as the time taken for the integrated pulse from a detector to rise from A% to B% of its full amplitude. The use of these parameters are usually restricted to the determination of the radial dependence thereof. This radial dependence of the rise time parameters are usually taken as a signature of the particle interaction characteristics in the shower. As these parameters have a stochastic nature, it seems reasonable that one should also take notice of this aspect of the rise time parameters. A statistical approach to rise time parameters is presented.

  9. Diet of Theropithecus from 4 to 1 Ma in Kenya

    NASA Astrophysics Data System (ADS)

    Cerling, Thure E.; Chritz, Kendra L.; Jablonski, Nina G.; Leakey, Meave G.; Kyalo Manthi, Fredrick

    2013-06-01

    Theropithecus was a common large-bodied primate that co-occurred with hominins in many Plio-Pleistocene deposits in East and South Africa. Stable isotope analyses of tooth enamel from T. brumpti (4.0-2.5 Ma) and T. oswaldi (2.0-1.0 Ma) in Kenya show that the earliest Theropithecus at 4 Ma had a diet dominated by C4 resources. Progressively, this genus increased the proportion of C4-derived resources in its diet and by 1.0 Ma, had a diet that was nearly 100% C4-derived. It is likely that this diet was comprised of grasses or sedges; stable isotopes cannot, by themselves, give an indication of the relative importance of leaves, seeds, or underground storage organs to the diet of this primate. Theropithecus throughout the 4- to 1-Ma time range has a diet that is more C4-based than contemporaneous hominins of the genera Australopithecus, Kenyanthropus, and Homo; however, Theropithecus and Paranthropus have similar proportions of C4-based resources in their respective diets.

  10. Diet of Theropithecus from 4 to 1 Ma in Kenya.

    PubMed

    Cerling, Thure E; Chritz, Kendra L; Jablonski, Nina G; Leakey, Meave G; Manthi, Fredrick Kyalo

    2013-06-25

    Theropithecus was a common large-bodied primate that co-occurred with hominins in many Plio-Pleistocene deposits in East and South Africa. Stable isotope analyses of tooth enamel from T. brumpti (4.0-2.5 Ma) and T. oswaldi (2.0-1.0 Ma) in Kenya show that the earliest Theropithecus at 4 Ma had a diet dominated by C4 resources. Progressively, this genus increased the proportion of C4-derived resources in its diet and by 1.0 Ma, had a diet that was nearly 100% C4-derived. It is likely that this diet was comprised of grasses or sedges; stable isotopes cannot, by themselves, give an indication of the relative importance of leaves, seeds, or underground storage organs to the diet of this primate. Theropithecus throughout the 4- to 1-Ma time range has a diet that is more C4-based than contemporaneous hominins of the genera Australopithecus, Kenyanthropus, and Homo; however, Theropithecus and Paranthropus have similar proportions of C4-based resources in their respective diets. PMID:23733967

  11. Scaling of X pinches from 1 MA to 6 MA.

    SciTech Connect

    Bland, Simon Nicholas; McBride, Ryan D.; Wenger, David Franklin; Sinars, Daniel Brian; Chittenden, Jeremy Paul; Pikuz, Sergei A.; Harding, Eric; Jennings, Christopher A.; Ampleford, David J.; Yu, Edmund P.; Cuneo, Michael Edward; Shelkovenko, Tatiana A.; Hansen, Stephanie B.

    2010-09-01

    This final report for Project 117863 summarizes progress made toward understanding how X-pinch load designs scale to high currents. The X-pinch load geometry was conceived in 1982 as a method to study the formation and properties of bright x-ray spots in z-pinch plasmas. X-pinch plasmas driven by 0.2 MA currents were found to have source sizes of 1 micron, temperatures >1 keV, lifetimes of 10-100 ps, and densities >0.1 times solid density. These conditions are believed to result from the direct magnetic compression of matter. Physical models that capture the behavior of 0.2 MA X pinches predict more extreme parameters at currents >1 MA. This project developed load designs for up to 6 MA on the SATURN facility and attempted to measure the resulting plasma parameters. Source sizes of 5-8 microns were observed in some cases along with evidence for high temperatures (several keV) and short time durations (<500 ps).

  12. Diet of Theropithecus from 4 to 1 Ma in Kenya

    PubMed Central

    Cerling, Thure E.; Chritz, Kendra L.; Jablonski, Nina G.; Leakey, Meave G.; Manthi, Fredrick Kyalo

    2013-01-01

    Theropithecus was a common large-bodied primate that co-occurred with hominins in many Plio-Pleistocene deposits in East and South Africa. Stable isotope analyses of tooth enamel from T. brumpti (4.0–2.5 Ma) and T. oswaldi (2.0–1.0 Ma) in Kenya show that the earliest Theropithecus at 4 Ma had a diet dominated by C4 resources. Progressively, this genus increased the proportion of C4-derived resources in its diet and by 1.0 Ma, had a diet that was nearly 100% C4-derived. It is likely that this diet was comprised of grasses or sedges; stable isotopes cannot, by themselves, give an indication of the relative importance of leaves, seeds, or underground storage organs to the diet of this primate. Theropithecus throughout the 4- to 1-Ma time range has a diet that is more C4-based than contemporaneous hominins of the genera Australopithecus, Kenyanthropus, and Homo; however, Theropithecus and Paranthropus have similar proportions of C4-based resources in their respective diets. PMID:23733967

  13. Coefficient of restitution dependence of intruder rise time in two-dimensional Brazil-nut effect

    NASA Astrophysics Data System (ADS)

    Kesuma, T.; Aji, D. P. Purwa; Viridi, S.; Suprijadi

    2016-04-01

    Brazil-Nut Effect (BNE) is a granular material phenomenon, where larger grains (usually known as intruder) rise to the top when the granular system vibrated. We observe a single intruder rise time of BNE phenomenon in a two-dimensional molecular dynamics simulation of hard spheres collision scheme. Some experiments have shown that some granular properties, such as size and density ratio, play an important role to determine the rise time. However, other property, such as coefficients of restitution, is considered not to have a measurable impact. We explore the intruder inelasticity dependence of the rise time by varying its coefficient of restitution. We found that the intruder rise time tends to be flat for relatively high coefficient of restitution and increases exponentially below a certain deflecting point for low coefficient of restitution. This holds for specific mass ratio.

  14. Influence of voltage rise time on microwave generation in relativistic backward wave oscillator

    SciTech Connect

    Wu, Ping; Deng, Yuqun; Sun, Jun; Teng, Yan; Shi, Yanchao; Chen, Changhua

    2015-10-15

    In relativistic backward wave oscillators (RBWOs), although the slow wave structure (SWS) and electron beam determine the main characteristics of beam-wave interaction, many other factors can also significantly affect the microwave generation process. This paper investigates the influence of voltage rise time on beam-wave interaction in RBWOs. Preliminary analysis and PIC simulations demonstrate if the voltage rise time is moderately long, the microwave frequency will gradually increase during the startup process until the voltage reaches its amplitude, which can be explained by the dispersion relation. However, if the voltage rise time is long enough, the longitudinal resonance of the finitely-long SWS will force the RBWO to work with unwanted longitudinal modes for a while and then gradually hop to the wanted longitudinal mode, and this will lead to an impure microwave frequency spectrum. Besides, a longer voltage rise time will delay the startup process and thus lead to a longer microwave saturation time. And if unwanted longitudinal modes are excited due to long voltage rise time, the microwave saturation time will be further lengthened. Therefore, the voltage rise time of accelerators adopted in high power microwave technology should not be too long in case unwanted longitudinal modes are excited.

  15. Responses of inferior collicular neurones of bats to tone bursts with different rise times

    PubMed Central

    Suga, N.

    1971-01-01

    1. A study was made of the responses of single neurones in the inferior colliculus of bats to tone bursts with different rise times (or with different rates of amplitude increase) in order to determine whether the neurones were specialized for analysis of amplitude-modulated sound, especially the rising phase in amplitude. 2. The response patterns of neurones which showed phasic on-responses usually did not change with rise time, although the response patterns of some neurones changed from phasic on-responses to inhibitory responses. 3. The thresholds of responses to tone bursts increased when the rise time was lengthened. The amount of increase greatly differed from neurone to neurone. For the excitation of neurones which showed a large increase in threshold, the stimulus amplitude should quickly increase in amplitude. For tone bursts with a short rise time, some neurones showed an upper-threshold above which the sounds failed to excite them. The upper-threshold usually disappeared when the rise time was lengthened. For the excitation of neurones which showed an upper-threshold, the rate of amplitude increase and its extent were very important parameters. 4. Lengthening the rise time of a tone burst from 0·5 to 98 msec caused various types of change in the excitatory area. In some cases, there was a diminution of the area and, in others, there was an expansion of the area. Neurones showing these changes may be considered to be specialized for responding to tone bursts with either a rapid or slow increase in amplitude. 5. Changes with rise time occurred not only in the excitatory area, but also in the inhibitory area. The change in the inhibitory area of a given neurone, however, was not necessarily the same as that in the excitatory area. 6. The latency of response usually changed as a function of stimulus amplitude and rise time. In 26% of the neurones studied, however, the latency was relatively constant regardless of stimulus amplitude and rise time. Some of

  16. CONSTRAINING PHYSICAL PROPERTIES OF TYPE IIn SUPERNOVAE THROUGH RISE TIMES AND PEAK LUMINOSITIES

    SciTech Connect

    Moriya, Takashi J.; Maeda, Keiichi

    2014-08-01

    We investigate the diversity in the wind density, supernova ejecta energy, and ejecta mass in Type IIn supernovae based on their rise times and peak luminosities. We show that the wind density and supernova ejecta properties can be estimated independently if both the rise time and peak luminosity are observed. The peak luminosity is mostly determined by the supernova properties and the rise time can be used to estimate the wind density. We find that the ejecta energies of Type IIn supernovae need to vary by factors of 0.2-5 from the average if their ejecta masses are similar. The diversity in the observed rise times indicates that their wind densities vary by factors of 0.2-2 from the average. We show that Type IIn superluminous supernovae should have not only large wind density but also large ejecta energy and/or small ejecta mass to explain their large luminosities and the rise times at the same time. We also note that shock breakout does not necessarily occur in the wind even if it is optically thick, except for the case of superluminous supernovae, and we analyze the observational data both with and without assuming that the shock breakout occurs in the dense wind of Type IIn supernovae.

  17. Dependence of current rise time on laser-triggered discharge plasma

    NASA Astrophysics Data System (ADS)

    Lim, Soowon; Kamohara, Takashi; Hosseini, S. Hamid R.; Katsuki, Sunao

    2016-07-01

    A powerful, stable extreme ultraviolet (EUV) source is the most important component for EUV lithography and EUV mask inspection. Here, we investigate the characteristics of laser-triggered discharge plasma at three different current rise times, fast, middle and slow. A height-adjustable coaxial birdcage was used to change circuit inductance. The rise time was varied between 30 ns-55 ns with peak current of 10 kA. The time-integrated EUV (at 13.5 nm in 2% bandwidth) intensity for the fast rise time was found to be 55% stronger than that of the slow rise time despite its lower energy. A high-speed Mach-Zehnder interferogram and visible imaging of the pinch plasma were employed to discuss plasma compression processes qualitatively and quantitatively. Also discharge produced debris was investigated using a silicon-crystal witness plate. The fast rise current was found to have advantages such as lower debris, higher EUV intensity, and possibility of suppressing instability in comparison with the slow rise time. As expected, total debris amounts lessened proportionally to the primary charged energy, as found from a comparison of fast and slow rise currents.

  18. Dependence of current rise time on laser-triggered discharge plasma

    NASA Astrophysics Data System (ADS)

    Lim, Soowon; Kamohara, Takashi; Hosseini, S. Hamid R.; Katsuki, Sunao

    2016-07-01

    A powerful, stable extreme ultraviolet (EUV) source is the most important component for EUV lithography and EUV mask inspection. Here, we investigate the characteristics of laser-triggered discharge plasma at three different current rise times, fast, middle and slow. A height-adjustable coaxial birdcage was used to change circuit inductance. The rise time was varied between 30 ns–55 ns with peak current of 10 kA. The time-integrated EUV (at 13.5 nm in 2% bandwidth) intensity for the fast rise time was found to be 55% stronger than that of the slow rise time despite its lower energy. A high-speed Mach–Zehnder interferogram and visible imaging of the pinch plasma were employed to discuss plasma compression processes qualitatively and quantitatively. Also discharge produced debris was investigated using a silicon-crystal witness plate. The fast rise current was found to have advantages such as lower debris, higher EUV intensity, and possibility of suppressing instability in comparison with the slow rise time. As expected, total debris amounts lessened proportionally to the primary charged energy, as found from a comparison of fast and slow rise currents.

  19. Discriminating cosmic muons and X-rays based on rise time using a GEM detector

    NASA Astrophysics Data System (ADS)

    Wu, Hui-Yin; Zhao, Sheng-Ying; Wang, Xiao-Dong; Zhang, Xian-Ming; Qi, Hui-Rong; Zhang, Wei; Wu, Ke-Yan; Hu, Bi-Tao; Zhang, Yi

    2016-08-01

    Gas electron multiplier (GEM) detectors have been used in cosmic muon scattering tomography and neutron imaging over the last decade. In this work, a triple GEM device with an effective readout area of 10 cm × 10 cm is developed, and a method of discriminating between cosmic muons and X-rays based on rise time is tested. The energy resolution of the GEM detector is tested by 55Fe ray source to prove the GEM detector has a good performance. Analysis of the complete signal-cycles allows us to get the rise time and pulse heights. The experiment result indicates that cosmic muons and X-rays can be discriminated with an appropriate rise time threshold. Supported by National Natural Science Foundation of China (11135002, 11275235, 11405077, 11575073)

  20. Extremum seeking-based optimization of high voltage converter modulator rise-time

    SciTech Connect

    Scheinker, Alexander; Bland, Michael; Krstic, Miroslav; Audia, Jeff

    2013-02-01

    We digitally implement an extremum seeking (ES) algorithm, which optimizes the rise time of the output voltage of a high voltage converter modulator (HVCM) at the Los Alamos Neutron Science Center (LANSCE) HVCM test stand by iteratively, simultaneously tuning the first 8 switching edges of each of the three phase drive waveforms (24 variables total). We achieve a 50 μs rise time, which is reduction in half compared to the 100 μs achieved at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory. Considering that HVCMs typically operate with an output voltage of 100 kV, with a 60Hz repetition rate, the 50 μs rise time reduction will result in very significant energy savings. The ES algorithm will prove successful, despite the noisy measurements and cost calculations, confirming the theoretical results that the algorithm is not affected by noise whose frequency components are independent of the perturbing frequencies.

  1. Rise Time of the Simulated VERITAS 12 m Davies-Cotton Reflector

    SciTech Connect

    White, Richard J.

    2005-02-21

    The Very Energetic Radiation Imaging Telescope Array System (VERITAS) will utilise Imaging Atmospheric Cherenkov Telescopes (IACTs) based on a Davies-Cotton design with f-number f/1.0 to detect cosmic gamma-rays. Unlike a parabolic reflector, light from the Davies-Cotton does not arrive isochronously at the camera. Here the effect of the telescope geometry on signal rise-time is examined. An almost square-pulse arrival time profile with a rise time of 1.7 ns is found analytically and confirmed through simulation.

  2. Rise Time Perception in Children with Reading and Combined Reading and Language Difficulties

    ERIC Educational Resources Information Center

    Beattie, Rachel L.; Manis, Franklin R.

    2013-01-01

    Using a non-speech-specific measure of prosody, rise time perception, Goswami and her colleagues have found that individuals with dyslexia perform significantly worse than nonimpaired readers. Studies have also found that children and adults with specific language impairment were impaired on these tasks. Despite the high comorbidity of these…

  3. Rise Time. Operational Control Tests for Wastewater Treatment Facilities. Instructor's Manual [and] Student Workbook.

    ERIC Educational Resources Information Center

    Carnegie, John W.

    The rise time test (along with the settleometer procedure) is used to monitor sludge behavior in the secondary clarifier of an activated sludge system. The test monitors the effect of the nitrification/denitrification process and aids the operator in determining optimum clarifier sludge detention time and, to some extent, optimum degree of…

  4. Transistorized Marx bank pulse circuit provides voltage multiplication with nanosecond rise-time

    NASA Technical Reports Server (NTRS)

    Jung, E. A.; Lewis, R. N.

    1968-01-01

    Base-triggered avalanche transistor circuit used in a Marx bank pulser configuration provides voltage multiplication with nanosecond rise-time. The avalanche-mode transistors replace conventional spark gaps in the Marx bank. The delay time from an input signal to the output signal to the output is typically 6 nanoseconds.

  5. Rise Time Perception and Detection of Syllable Stress in Adults with Developmental Dyslexia

    ERIC Educational Resources Information Center

    Leong, Victoria; Hamalainen, Jarmo; Soltesz, Fruzsina; Goswami, Usha

    2011-01-01

    Introduction: The perception of syllable stress has not been widely studied in developmental dyslexia, despite strong evidence for auditory rhythmic perceptual difficulties. Here we investigate the hypothesis that perception of sound rise time is related to the perception of syllable stress in adults with developmental dyslexia. Methods: A…

  6. Effect of air on energy and rise-time spectra measured by proportional gas counter

    SciTech Connect

    Kawano, T.; Tanaka, M.; Isozumi, S.; Isozumi, Y.; Tosaki, M.; Sugiyama, T.

    2015-03-15

    Air exerts a negative effect on radiation detection using a gas counter because oxygen contained in air has a high electron attachment coefficient and can trap electrons from electron-ion pairs created by ionization from incident radiation in counting gas. This reduces radiation counts. The present study examined the influence of air on energy and rise-time spectra measurements using a proportional gas counter. In addition, a decompression procedure method was proposed to reduce the influence of air and its effectiveness was investigated. For the decompression procedure, the counting gas inside the gas counter was decompressed below atmospheric pressure before radiation detection. For the spectrum measurement, methane as well as various methane and air mixtures were used as the counting gas to determine the effect of air on energy and rise-time spectra. Results showed that the decompression procedure was effective for reducing or eliminating the influence of air on spectra measurement using a proportional gas counter. (authors)

  7. Fast Rise Time and High Voltage Nanosecond Pulses at High Pulse Repetition Frequency

    NASA Astrophysics Data System (ADS)

    Miller, Kenneth E.; Ziemba, Timothy; Prager, James; Picard, Julian; Hashim, Akel

    2015-09-01

    Eagle Harbor Technologies (EHT), Inc. is conducting research to decrease the rise time and increase the output voltage of the EHT Nanosecond Pulser product line, which allows for independently, user-adjustable output voltage (0 - 20 kV), pulse width (20 - 500 ns), and pulse repetition frequency (0 - 100 kHz). The goals are to develop higher voltage pulses (50 - 60 kV), decrease the rise time from 20 to below 10 ns, and maintain the high pulse repetition capabilities. These new capabilities have applications to pseudospark generation, corona production, liquid discharges, and nonlinear transmission line driving for microwave production. This work is supported in part by the US Navy SBIR program.

  8. Rise time of voltage pulses in NbN superconducting single photon detectors

    NASA Astrophysics Data System (ADS)

    Smirnov, K. V.; Divochiy, A. V.; Vakhtomin, Yu. B.; Sidorova, M. V.; Karpova, U. V.; Morozov, P. V.; Seleznev, V. A.; Zotova, A. N.; Vodolazov, D. Yu.

    2016-08-01

    We have found experimentally that the rise time of voltage pulse in NbN superconducting single photon detectors increases nonlinearly with increasing the length of the detector L. The effect is connected with dependence of resistance of the detector Rn, which appears after photon absorption, on its kinetic inductance Lk and, hence, on the length of the detector. This conclusion is confirmed by our calculations in the framework of two temperature model.

  9. Pulse Rise Time Characterization of a High Pressure Xenon Gamma Detector for use in Resolution Enhancement

    SciTech Connect

    TROYER, G.L.

    2000-08-25

    High pressure xenon ionization chamber detectors are possible alternatives to traditional thallium doped sodium iodide (NaI(Tl)) and hyperpure germanium as gamma spectrometers in certain applications. Xenon detectors incorporating a Frisch grid exhibit energy resolutions comparable to cadmium/zinc/telluride (CZT) (e.g. 2% {at} 662keV) but with far greater sensitive volumes. The Frisch grid reduces the position dependence of the anode pulse risetimes, but it also increases the detector vibration sensitivity, anode capacitance, voltage requirements and mechanical complexity. We have been investigating the possibility of eliminating the grid electrode in high-pressure xenon detectors and preserving the high energy resolution using electronic risetime compensation methods. A two-electrode cylindrical high pressure xenon gamma detector coupled to time-to-amplitude conversion electronics was used to characterize the pulse rise time of deposited gamma photons. Time discrimination was used to characterize the pulse rise time versus photo peak position and resolution. These data were collected to investigate the effect of pulse rise time compensation on resolution and efficiency.

  10. Extremum seeking-based optimization of high voltage converter modulator rise-time

    DOE PAGES

    Scheinker, Alexander; Bland, Michael; Krstic, Miroslav; Audia, Jeff

    2013-02-01

    We digitally implement an extremum seeking (ES) algorithm, which optimizes the rise time of the output voltage of a high voltage converter modulator (HVCM) at the Los Alamos Neutron Science Center (LANSCE) HVCM test stand by iteratively, simultaneously tuning the first 8 switching edges of each of the three phase drive waveforms (24 variables total). We achieve a 50 μs rise time, which is reduction in half compared to the 100 μs achieved at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory. Considering that HVCMs typically operate with an output voltage of 100 kV, with a 60Hz repetitionmore » rate, the 50 μs rise time reduction will result in very significant energy savings. The ES algorithm will prove successful, despite the noisy measurements and cost calculations, confirming the theoretical results that the algorithm is not affected by noise whose frequency components are independent of the perturbing frequencies.« less

  11. Effect of stratification and geometrical spreading on sonic boom rise time

    NASA Technical Reports Server (NTRS)

    Cleveland, Robin O.; Hamilton, Mark F.; Blackstock, David T.

    1994-01-01

    The purpose of our investigation is to determine the effect of unsteadiness (not associated with turbulence) on rise time. The unsteadiness considered here is due to (1) geometrical spreading, (2) stratification, which includes variation in density, temperature, and relative humidity, and (3) N shaped waveform. A very general Burgers equation, which includes all these effects, is the propagation model for our study. The equation is solved by a new computational algorithm in which all the calculations are done in the time domain. The present paper is a progress report in which some of the factors contributing to unsteadiness are studied, namely geometrical spreading and variation in relative humidity. The work of Pierce and Kang, which motivated our study, is first reviewed. We proceed with a discussion of the Burgers equation model and the algorithm for solving the equation. Some comparison tests to establish the validity of the algorithm are presented. The algorithm is then used to determine the distance required for a steady-state shock, on encountering an abrupt change in relative humidity, to reach a new steady state based on the new humidity. It is found that the transition distance for plane shocks of amplitude 70 Pa is about 4 km when the change in relative humidity is 10 percent. Shocks of amplitude 140 Pa require less distance. The effect of spherical and cylindrical spreading is also considered. We demonstrate that a spreading shock wave never reaches steady state and that its rise time will be less than the equivalent steady state shock. Finally we show that an N wave has a slightly shorter rise time than a step shock of the same amplitude.

  12. Subjective response to sonic booms having different shapes, rise times, and durations

    NASA Technical Reports Server (NTRS)

    Mccurdy, David A.

    1994-01-01

    Two laboratory experiments were conducted to quantify the subjective response of people to simulated outdoor sonic booms having different pressure signatures. The specific objectives of the experiments were to compare subjective response to sonic booms when described in terms of 'loudness' and 'annoyance'; to determine the ability of various noise metrics to predict subjective response to sonic booms; to determine the effects on subjective response of rise time, duration, and level; and to compare the subjective response to 'N-wave' sonic boom signatures with the subjective response to 'minimized' sonic boom signatures. The experiments were conducted in a computer-controlled, man-rated sonic boom simulator capable of reproducing user-specified pressure signatures for a wide range of sonic boom parameters. One hundred and fifty sonic booms representing different combinations of two wave shapes, four rise times, seven durations, and three peak overpressures were presented to 36 test subjects in each experiment. The test subjects in the first experiment made judgments of 'loudness' while the test subjects in the second experiment judged 'annoyance.' Subjective response to sonic booms was the same whether expressed in terms of loudness or in terms of annoyance. Analyses of several different noise metrics indicated that A-weighted sound exposure level and Perceived Level were the best predictors of subjective response. Further analyses indicated that, of these two noise metrics, only Perceived Level completely accounted for the effects of wave shape, rise time, and peak overpressure. Neither metric fully accounted for the effect of duration. However, the magnitude of the duration effect was small over the very wide range of durations considered.

  13. DOI Determination by Rise Time Discrimination in Single-Ended Readout for TOF PET Imaging

    PubMed Central

    Wiener, R.I.; Surti, S.; Karp, J.S.

    2013-01-01

    Clinical TOF PET systems achieve detection efficiency using thick crystals, typically of thickness 2–3cm. The resulting dispersion in interaction depths degrades spatial resolution for increasing radial positions due to parallax error. Furthermore, interaction depth dispersion results in time pickoff dispersion and thus in degraded timing resolution, and is therefore of added concern in TOF scanners. Using fast signal digitization, we characterize the timing performance, pulse shape and light output of LaBr3:Ce, CeBr3 and LYSO. Coincidence timing resolution is shown to degrade by ~50ps/cm for scintillator pixels of constant cross section and increasing length. By controlling irradiation depth in a scintillator pixel, we show that DOI-dependence of time pickoff is a significant factor in the loss of timing performance in thick detectors. Using the correlated DOI-dependence of time pickoff and charge collection, we apply a charge-based correction to the time pickoff, obtaining improved coincidence timing resolution of <200ps for a uniform 4×4×30mm3 LaBr3 pixel. In order to obtain both DOI identification and improved timing resolution, we design a two layer LaBr3[5%Ce]/LaBr3[30%Ce] detector of total size 4×4×30mm3, exploiting the dependence of scintillator rise time on [Ce] in LaBr3:Ce. Using signal rise time to determine interaction layer, excellent interaction layer discrimination is achieved, while maintaining coincidence timing resolution of <250ps and energy resolution <7% using a R4998 PMT. Excellent layer separation and timing performance is measured with several other commercially-available TOF photodetectors, demonstrating the practicality of this design. These results indicate the feasibility of rise time discrimination as a technique for measuring event DOI while maintaining sensitivity, timing and energy performance, in a well-known detector architecture. PMID:24403611

  14. Rise time in 20-32 keV impulsive X-radiation

    NASA Technical Reports Server (NTRS)

    Vorpahl, J. A.; Takakura, T.

    1974-01-01

    A new property of the X-ray impulsive component observed in solar flares is discussed, giving attention to the relation between the slope of the electron power spectrum and the rise time in the 20-32 keV X-ray spike. This particular energy range was chosen because it offered the greatest number of impulsive events while being sufficiently high to avoid contamination by soft X radiation. It is found for the thin-target model that the electron spectrum tends to be softer when the acceleration rate is smaller.

  15. CHARACTERISTICS OF A FAST RISE TIME POWER SUPPLY FOR A PULSED PLASMA REACTOR FOR CHEMICAL VAPOR DESTRUCTION

    EPA Science Inventory

    Rotating spark gap devices for switching high-voltage direct current (dc) into a corona plasma reactor can achieve pulse rise times in the range of tens of nanoseconds. The fast rise times lead to vigorous plasma generation without sparking at instantaneous applied voltages highe...

  16. A compact, low jitter, nanosecond rise time, high voltage pulse generator with variable amplitude.

    PubMed

    Mao, Jiubing; Wang, Xin; Tang, Dan; Lv, Huayi; Li, Chengxin; Shao, Yanhua; Qin, Lan

    2012-07-01

    In this paper, a compact, low jitter, nanosecond rise time, command triggered, high peak power, gas-switch pulse generator system is developed for high energy physics experiment. The main components of the system are a high voltage capacitor, the spark gap switch and R = 50 Ω load resistance built into a structure to obtain a fast high power pulse. The pulse drive unit, comprised of a vacuum planar triode and a stack of avalanche transistors, is command triggered by a single or multiple TTL (transistor-transistor logic) level pulses generated by a trigger pulse control unit implemented using the 555 timer circuit. The control unit also accepts user input TTL trigger signal. The vacuum planar triode in the pulse driving unit that close the first stage switches is applied to drive the spark gap reducing jitter. By adjusting the charge voltage of a high voltage capacitor charging power supply, the pulse amplitude varies from 5 kV to 10 kV, with a rise time of <3 ns and the maximum peak current up to 200 A (into 50 Ω). The jitter of the pulse generator system is less than 1 ns. The maximum pulse repetition rate is set at 10 Hz that limited only by the gas-switch and available capacitor recovery time.

  17. Rise time and response measurements on a LiSOCl2 cell

    NASA Technical Reports Server (NTRS)

    Bastien, Caroline; Lecomte, Eric J.

    1992-01-01

    Dynamic impedance tests were performed on a 180 Ah LiSOCl2 cell in the frame of a short term work contract awarded by Aerospatiale as part of the Hermes Space Plane development work. These tests consisted of rise time and response measurements. The rise time test was performed to show the ability to deliver 4 KW, in the nominal voltage range (75-115 V), within less than 100 microseconds, and after a period at rest of 13 days. The response measurements test consisted of step response and frequency response tests. The frequency response test was performed to characterize the response of the LiSOCl2 cell to a positive or negative load step of 10 A starting from various currents. The test was performed for various depths of discharge and various temperatures. The test results were used to build a mathematical, electrical model of the LiSOCl2 cell which are also presented. The test description, test results, electrical modelization description, and conclusions are presented.

  18. A compact, low jitter, nanosecond rise time, high voltage pulse generator with variable amplitude

    NASA Astrophysics Data System (ADS)

    Mao, Jiubing; Wang, Xin; Tang, Dan; Lv, Huayi; Li, Chengxin; Shao, Yanhua; Qin, Lan

    2012-07-01

    In this paper, a compact, low jitter, nanosecond rise time, command triggered, high peak power, gas-switch pulse generator system is developed for high energy physics experiment. The main components of the system are a high voltage capacitor, the spark gap switch and R = 50 Ω load resistance built into a structure to obtain a fast high power pulse. The pulse drive unit, comprised of a vacuum planar triode and a stack of avalanche transistors, is command triggered by a single or multiple TTL (transistor-transistor logic) level pulses generated by a trigger pulse control unit implemented using the 555 timer circuit. The control unit also accepts user input TTL trigger signal. The vacuum planar triode in the pulse driving unit that close the first stage switches is applied to drive the spark gap reducing jitter. By adjusting the charge voltage of a high voltage capacitor charging power supply, the pulse amplitude varies from 5 kV to 10 kV, with a rise time of <3 ns and the maximum peak current up to 200 A (into 50 Ω). The jitter of the pulse generator system is less than 1 ns. The maximum pulse repetition rate is set at 10 Hz that limited only by the gas-switch and available capacitor recovery time.

  19. A compact, low jitter, nanosecond rise time, high voltage pulse generator with variable amplitude.

    PubMed

    Mao, Jiubing; Wang, Xin; Tang, Dan; Lv, Huayi; Li, Chengxin; Shao, Yanhua; Qin, Lan

    2012-07-01

    In this paper, a compact, low jitter, nanosecond rise time, command triggered, high peak power, gas-switch pulse generator system is developed for high energy physics experiment. The main components of the system are a high voltage capacitor, the spark gap switch and R = 50 Ω load resistance built into a structure to obtain a fast high power pulse. The pulse drive unit, comprised of a vacuum planar triode and a stack of avalanche transistors, is command triggered by a single or multiple TTL (transistor-transistor logic) level pulses generated by a trigger pulse control unit implemented using the 555 timer circuit. The control unit also accepts user input TTL trigger signal. The vacuum planar triode in the pulse driving unit that close the first stage switches is applied to drive the spark gap reducing jitter. By adjusting the charge voltage of a high voltage capacitor charging power supply, the pulse amplitude varies from 5 kV to 10 kV, with a rise time of <3 ns and the maximum peak current up to 200 A (into 50 Ω). The jitter of the pulse generator system is less than 1 ns. The maximum pulse repetition rate is set at 10 Hz that limited only by the gas-switch and available capacitor recovery time. PMID:22852729

  20. Rise Times of Solar Energetic Particle Events and Speeds of CMEs

    NASA Astrophysics Data System (ADS)

    Kahler, S.; Reames, D.

    2002-12-01

    Gradual solar energetic particle (SEP) events are assumed to be produced in coronal and interplanetary shocks driven by fast coronal mass ejections (CMEs). These fast CMEs are decelerated as they move through the slower ambient solar wind. However, the Alfven speed is decreasing with increasing distance. Faster CMEs may therefore continue to drive strong shocks for longer characteristic times than do the slower CMEs, such that shock production and injection of SEPs of a given energy will also continue longer with the faster CMEs. We test this proposition observationally by comparing the times to maxima of 20 MeV SEP events with the observed speeds of associated CMEs. The SEP/CME events are sorted by solar longitude to factor out the longitudinal dependence of the SEP rise times. A preliminary analysis comparing 20 MeV protons from the GSFC EPACT detector on the Wind satellite with CMEs observed by the LASCO coronagraph on the SOHO spacecraft showed a correlation between SEP rise times and CME speeds. We expand the database to include the 1996-2001 period for a more definitive test of the correlation. The implications of the results will be discussed.

  1. Rise time of inverted triangular prism intruder in vibrating granular bed: Experiments and model

    NASA Astrophysics Data System (ADS)

    Nuraini, N.; Adriani, I. K.; Baladram, M. S.; Viridi, S.

    2012-05-01

    Experiment results and a qualitative model of the phenomenon called Brazil nut effect (BNE) with inverted triangular prism are reported in this work. The model is constructed by considering some forces (earth gravitational force, buoyant force, and fluid viscous force) and using Newton's second law of motion. The rise time of BNE T is defined as time needed for the intruder to be on granular surface with all of his parts (no part is still immersed in the granular bed). One side of the triangular base of the intruder l is varied from 1.5 to 5 cm with other two sides are kept in constant values (1 and 3 cm). It has been observed in experiment that l with value 3-4 cm gives the smaller rise time. Plot of T versus l has the form of concave up parabolic curve with minimum lies at l between 3-4 cm. This observation has been confirmed by the proposed model with the same order of magnitude and similar curve trend.

  2. Digital Rise-Time Discrimination of Pulses from the Tigress Integrated Plunger Silicon PIN Diode Wall

    NASA Astrophysics Data System (ADS)

    Voss, P.; Henderson, R.; Andreoiu, C.; Ashley, R.; Ball, G. C.; Bender, P. C.; Chester, A.; Cross, D. S.; Drake, T. E.; Garnsworthy, A. B.; Hackman, G.; Ketelhut, S.; Krücken, R.; Miller, D.; Rajabali, M. M.; Starosta, K.; Svensson, C. E.; Tardiff, E.; Unsworth, C.; Wang, Z.-M.

    Electromagnetic transition rate measurements play an important role in characterizing the evolution of nuclear structure with increasing proton-neutron asymmetry. At TRIUMF, the TIGRESS Integrated Plunger device and its suite of ancillary detector systems have been implemented for charged-particle tagging and light-ion identification in coincidence with gamma-ray spectroscopy for Doppler-shift lifetime studies and low-energy Coulomb excitation measurements. Digital pulse-shape analysis of signals from these ancillary detectors for particle identification improves the signal-to-noise ratio of gamma-ray energy spectra. Here, we illustrate the reaction-channel selectivity achieved by utilizing digital rise-time discrimination of waveforms from alpha particles and carbon ions detected with silicon PIN diodes, thereby enhancing gamma-ray line-shape signatures for precision lifetime studies.

  3. The Rise Time of Type Ia Supernovae from the Supernova Legacy Survey

    NASA Astrophysics Data System (ADS)

    Conley, A.; Howell, D. A.; Howes, A.; Sullivan, M.; Astier, P.; Balam, D.; Basa, S.; Carlberg, R. G.; Fouchez, D.; Guy, J.; Hook, I.; Neill, J. D.; Pain, R.; Perrett, K.; Pritchet, C. J.; Regnault, N.; Rich, J.; Taillet, R.; Aubourg, E.; Bronder, J.; Ellis, R. S.; Fabbro, S.; Filiol, M.; Le Borgne, D.; Palanque-Delabrouille, N.; Perlmutter, S.; Ripoche, P.

    2006-10-01

    We compare the rise times of nearby and distant Type Ia supernovae (SNe Ia) as a test for evolution using 73 high-redshift spectroscopically confirmed SNe Ia from the first 2 years of the 5 year Supernova Legacy Survey (SNLS) and published observations of nearby SNe. Because of the ``rolling'' search nature of the SNLS, our measurement is approximately 6 times more precise than previous studies, allowing for a more sensitive test of evolution between nearby and distant SNe. Adopting a simple t2 early-time model (as in previous studies), we find that the rest-frame B rise times for a fiducial SN Ia at high and low redshift are consistent, with values 19.10+0.18-0.17(stat)+/-0.2(syst) and 19.58+0.22-0.19 days, respectively; the statistical significance of this difference is only 1.4 σ. The errors represent the uncertainty in the mean rather than any variation between individual SNe. We also compare subsets of our high-redshift data set based on decline rate, host galaxy star formation rate, and redshift, finding no substantive evidence for any subsample dependence. Based on observations obtained with MegaPrime/MegaCam, a joint project of the Canada-France-Hawaii Telescope (CFHT) and CEA/DAPNIA, at CFHT, which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based in part on data products produced at the Canadian Astronomy Data Centre as part of the CFHT Legacy Survey, a collaborative project of NRC and CNRS.

  4. Temporal features of spectral integration in the inferior colliculus: effects of stimulus duration and rise time.

    PubMed

    Gans, Donald; Sheykholeslami, Kianoush; Peterson, Diana Coomes; Wenstrup, Jeffrey

    2009-07-01

    This report examines temporal features of facilitation and suppression that underlie spectrally integrative responses to complex vocal signals. Auditory responses were recorded from 160 neurons in the inferior colliculus (IC) of awake mustached bats. Sixty-two neurons showed combination-sensitive facilitation: responses to best frequency (BF) signals were facilitated by well-timed signals at least an octave lower in frequency, in the range 16-31 kHz. Temporal features and strength of facilitation were generally unaffected by changes in duration of facilitating signals from 4 to 31 ms. Changes in stimulus rise time from 0.5 to 5.0 ms had little effect on facilitatory strength. These results suggest that low frequency facilitating inputs to high BF neurons have phasic-on temporal patterns and are responsive to stimulus rise times over the tested range. We also recorded from 98 neurons showing low-frequency (11-32 kHz) suppression of higher BF responses. Effects of changing duration were related to the frequency of suppressive signals. Signals<23 kHz usually evoked suppression sustained throughout signal duration. This and other features of such suppression are consistent with a cochlear origin that results in masking of responses to higher, near-BF signal frequencies. Signals in the 23- to 30-kHz range-frequencies in the first sonar harmonic-generally evoked phasic suppression of BF responses. This may result from neural inhibitory interactions within and below IC. In many neurons, we observed two or more forms of the spectral interactions described here. Thus IC neurons display temporally and spectrally complex responses to sound that result from multiple spectral interactions at different levels of the ascending auditory pathway.

  5. A hybrid model for simulation of secondary electron emission in plasma immersion ion implantation under different pulse rise time

    SciTech Connect

    Navab Safa, N. Ghomi, H.

    2015-02-15

    A hybrid fluid Particle in Cell–Monte Carlo Collision (PiC–MCC) model is presented to study the effect of secondary electron emission on the plasma immersion ion implantation process under different pulse rise time. The model describes the temporal evolution of various parameters of plasma such as ion density, ion velocity, secondary electron density, and secondary electron current for different rise times. A 3D–3 V PiC–MCC model is developed to simulate the secondary electrons which are emitted from the sample surface while the plasma ions and electrons are treated using a 1D fluid model. The simulation results indicate that the secondary electron density and secondary electron current increase as the rise time decreases. The main differences between the results for different rise times are found during the initial phase of the pulse. The results are explained through studying the fundamental parameters of plasma.

  6. Rapid rise time pulsed magnetic field circuit for pump-probe field effect studies.

    PubMed

    Salaoru, T A; Woodward, Jonathan R

    2007-03-01

    Here we describe an electronic circuit capable of producing rapidly switched dc magnetic fields of up to 20 mT with a rise time of 10 ns and a pulse length variable from 50 ns to more than 10 micros, suitable for use in the study of magnetic field effects on radical pair (RP) reactions. This corresponds to switching the field on a time scale short relative to the lifetime of typical RPs and maintaining it well beyond their lifetimes. Previous experiments have involved discharging a capacitor through a low inductance coil for a limited time using a switching circuit. These suffer from decaying field strength over the duration of the pulse given primarily by the ratio of the pulse width to the RC constant of the circuit. We describe here a simple yet elegant solution that completely eliminates this difficulty by employing a feedback loop. This allows a constant field to be maintained over the entire length of the pulse. PMID:17411229

  7. A 200 kV fast rise time, low jitter, trigger system with magnetic pulse sharpener

    SciTech Connect

    Jaitly, N.C.; Coleman, M.D.; Ramrus, A.; Earley, L.M.; Downing, J.N.; Reisch, H.H.; Caudill, L.D.; Eversol, S.A.

    1992-09-01

    The DARHT Facility is being designed at Los Alamos national Laboratory to produce high resolution flash radiographs of hydrodynamic experiments. Two linear induction accelerators (LIA), each in the range of 16 to 20 MeV, will be used to produce intense bremsstrahlung X-ray pulses of short duration (60 ns flat top). Each LIA will produce a 3 kA, high brightness, electron beam using a 4 MeV injector and a series of 250 kV induction cells. Technology demonstration of key accelerator subsystems is under progress at the DARHT Integrated Test Stand (ITS). The eight inductions cells present in the ITS are driven by a Maxwell prototype Induction Cell Pulsed Power supply (ICPPS) which provides 250 kV, 70 ns pulses via four Blumieins. Each Blumiein drives two cells and is triggered using independently controlled trigger units. This turnkey DARHT Trigger System, consisting of four separate trigger units, provides 200 kV trigger pulses with low jitter and fast rise time to each of the four Blumiein coaxial spark gaps. Details of the trigger system design and results obtained during extensive testing at Maxwell are described.

  8. Individual differences in processing pitch contour and rise time in adults: A behavioral and electrophysiological study of Cantonese tone merging.

    PubMed

    Ou, Jinghua; Law, Sam-Po

    2016-06-01

    One way to understand the relationship between speech perception and production is to examine cases where the two dissociate. This study investigates the hypothesis that perceptual acuity reflected in event-related potentials (ERPs) to rise time of sound amplitude envelope and pitch contour [reflected in the mismatch negativity (MMN)] may associate with individual differences in production among speakers with otherwise comparable perceptual abilities. To test this hypothesis, advantage was taken of an on-going sound change-tone merging in Cantonese, and compared the ERPs between two groups of typically developed native speakers who could discriminate the high rising and low rising tones with equivalent accuracy but differed in the distinctiveness of their production of these tones. Using a passive oddball paradigm, early positive-going EEG components to rise time and MMN to pitch contour were elicited during perception of the two tones. Significant group differences were found in neural responses to rise time rather than pitch contour. More importantly, individual differences in efficiency of tone discrimination in response latency and magnitude of neural responses to rise time were correlated with acoustic measures of F0 offset and rise time differences in productions of the two rising tones.

  9. Individual differences in processing pitch contour and rise time in adults: A behavioral and electrophysiological study of Cantonese tone merging.

    PubMed

    Ou, Jinghua; Law, Sam-Po

    2016-06-01

    One way to understand the relationship between speech perception and production is to examine cases where the two dissociate. This study investigates the hypothesis that perceptual acuity reflected in event-related potentials (ERPs) to rise time of sound amplitude envelope and pitch contour [reflected in the mismatch negativity (MMN)] may associate with individual differences in production among speakers with otherwise comparable perceptual abilities. To test this hypothesis, advantage was taken of an on-going sound change-tone merging in Cantonese, and compared the ERPs between two groups of typically developed native speakers who could discriminate the high rising and low rising tones with equivalent accuracy but differed in the distinctiveness of their production of these tones. Using a passive oddball paradigm, early positive-going EEG components to rise time and MMN to pitch contour were elicited during perception of the two tones. Significant group differences were found in neural responses to rise time rather than pitch contour. More importantly, individual differences in efficiency of tone discrimination in response latency and magnitude of neural responses to rise time were correlated with acoustic measures of F0 offset and rise time differences in productions of the two rising tones. PMID:27369146

  10. Learning Novel Phonological Representations in Developmental Dyslexia: Associations with Basic Auditory Processing of Rise Time and Phonological Awareness

    ERIC Educational Resources Information Center

    Thomson, Jennifer M.; Goswami, Usha

    2010-01-01

    Across languages, children with developmental dyslexia are known to have impaired lexical phonological representations. Here, we explore associations between learning new phonological representations, phonological awareness, and sensitivity to amplitude envelope onsets (rise time). We show that individual differences in learning novel phonological…

  11. Turbulence Scales, Rise Times, Caustics, and the Simulation of Sonic Boom Propagation

    NASA Technical Reports Server (NTRS)

    Pierce, Allan D.

    1996-01-01

    The general topic of atmospheric turbulence effects on sonic boom propagation is addressed with especial emphasis on taking proper and efficient account of the contributions of the portion oi the turbulence that is associated with extremely high wavenumber components. The recent work reported by Bart Lipkens in his doctoral thesis is reexamined to determine whether the good agreement between his measured rise times with the 1971 theory of the author is fortuitous. It is argued that Lipken's estimate of the distance to the first caustic was a gross overestimate because of the use of a sound speed correlation function shaped like a gaussian curve. In particular, it is argued that the expected distance to the first caustic varies with the kinematic viscosity nu and the energy epsilon dissipated per unit mass per unit time, and the sound speed c as : d(sub first caustic) = nu(exp 7/12) c(exp 2/3)/ epsilon(exp 5/12)(nu x epsilon/c(exp 4))(exp a), where the exponent a is greater than -7/12 and can be argued to be either O or 1/24. In any event, the surprising aspect of the relationship is that it actually goes to zero as the viscosity goes to zero with s held constant. It is argued that the apparent overabundance of caustics can be grossly reduced by a general computational and analytical perspective that partitions the turbulence into two parts, divided by a wavenumber k(sub c). Wavenumbers higher than kc correspond to small-scale turbulence, and the associated turbulence can be taken into account by a renormalization of the ambient sound speed so that the result has a small frequency dependence that results from a spatial averaging over of the smaller-scale turbulent fluctuations. Selection of k(sub c). can be made so large that only a very small number of caustics are encountered if one adopts the premise that the frequency dispersion of pulses is caused by that part of the turbulence spectrum which lies in the inertial range originally predicted by Kolmogoroff. The

  12. Diversity of Decline-Rate-Corrected Type 1a Supernova Rise times:One Mode or Two?

    SciTech Connect

    Strovink, Mark

    2007-05-01

    B-band light-curve rise times for eight unusually well-observed nearby Type Ia supernova (SNe) are fitted by a newly developed template-building algorithm, using light-curve functions that are smooth, flexible, and free of potential bias from externally derived templates and other prior assumptions. From the available literature, photometric BVRI data collected over many months, including the earliest points, are reconciled, combined, and fitted to a unique time of explosion for each SN. On average, after they are corrected for light-curve decline rate, three SNe rise in 18.81 {+-} 0.36 days, while five SNe rise in 16.64 {+-} 0.21 days. If all eight SNe are sampled from a single parent population (a hypothesis not favored by statistical tests), the rms intrinsic scatter of the decline-rate-corrected SN rise time is 0.96{sub -0.25}{sup +0.52} days--a first measurement of this dispersion. The corresponding global mean rise time is 17.44 {+-} 0.39 days, where the uncertainty is dominated by intrinsic variance. This value is {approx}2 days shorter than two published averages that nominally are twice as precise, though also based on small samples. When comparing high-z to low-z SN luminosities for determining cosmological parameters, bias can be introduced by use of a light-curve template with an unrealistic rise time. If the period over which light curves are sampled depends on z in a manner typical of current search and measurement strategies, a two-day discrepancy in template rise time can bias the luminosity comparison by {approx}0.03 magnitudes.

  13. MOSFET solid state switching circuit improves the 0 to 99% rise time for framing camera deflection electronics

    SciTech Connect

    Rivera, A.T.; Thomas, S.

    1996-09-01

    We have improved the 0 to 99% rise time voltage on our 2 frame deflection plates from 160 to 65 nS with the addition of a peaking circuit that works in conjunction with our primary 2 frame deflection circuitry. Our peaking technique has applications to other HV pulsers including those which must drive 51 ohm loads. Generally, rise time voltages are measured between 10 and 90%. To minimize the camera image blur resulting from the dynamic influence of deflection plate potentials acting on photocathode electrons, it was necessary to design a circuit that would rise from 0 to the 99% voltage level in under 100nS. Once this voltage was reached, it was necessary to stay within 1% of the attained voltage level for a duration of 1 uS. This was accomplished with the use of MOSFET solid state switching.

  14. EARLY-PHASE PHOTOMETRY AND SPECTROSCOPY OF TRANSITIONAL TYPE Ia SN 2012ht: DIRECT CONSTRAINT ON THE RISE TIME

    SciTech Connect

    Yamanaka, Masayuki; Nogami, Daisaku; Maeda, Keiichi; Kawabata, Miho; Masumoto, Kazunari; Matsumoto, Katsura; Tanaka, Masaomi; Takaki, Katsutoshi; Ueno, Issei; Itoh, Ryosuke; Kawabata, Koji S.; Moritani, Yuki; Akitaya, Hiroshi; Yoshida, Michitoshi; Arai, Akira; Honda, Satoshi; Nishiyama, Koichi; Kabashima, Fujio

    2014-02-20

    We report photometric and spectroscopic observations of the nearby Type Ia Supernova (SN Ia) 2012ht from –15.8 days to +49.1 days after B-band maximum. The decline rate of the light curve is Δm {sub 15}(B) = 1.39 ± 0.05 mag, which is intermediate between normal and subluminous SNe Ia, and similar to that of the ''transitional'' Type Ia SN 2004eo. The spectral line profiles also closely resemble those of SN 2004eo. We were able to observe SN 2012ht at a very early phase, when it was still rising and was about three magnitudes fainter than at the peak. The rise time to the B-band maximum is estimated to be 17.6 ± 0.5 days and the time of the explosion is MJD 56277.98 ± 0.13. SN 2012ht is the first transitional SN Ia whose rise time is directly measured without using light curve templates, and the fifth SN Ia overall. This rise time is consistent with those of the other four SNe within the measurement error, even including the extremely early detection of SN 2013dy. The rising part of the light curve can be fitted by a quadratic function, and shows no sign of a shock-heating component due to the interaction of the ejecta with a companion star. The rise time is significantly longer than that inferred for subluminous SNe such as SN 1991bg, which suggests that a progenitor and/or explosion mechanism of transitional SNe Ia are more similar to normal SNe Ia rather than to subluminous SNe Ia.

  15. Interaction-powered supernovae: rise-time versus peak-luminosity correlation and the shock-breakout velocity

    SciTech Connect

    Ofek, Eran O.; Arcavi, Iair; Tal, David; Gal-Yam, Avishay; Ben-Ami, Sagi; De Cia, Annalisa; Yaron, Ofer; Sullivan, Mark; Kulkarni, Shrinivas R.; Cao, Yi; Nugent, Peter E.; Bersier, David; Cenko, S. Bradley; Filippenko, Alexei V.; Fransson, Claes; Kasliwal, Mansi M.; Laher, Russ; Surace, Jason; Quimby, Robert

    2014-06-20

    Interaction of supernova (SN) ejecta with the optically thick circumstellar medium (CSM) of a progenitor star can result in a bright, long-lived shock-breakout event. Candidates for such SNe include Type IIn and superluminous SNe. If some of these SNe are powered by interaction, then there should be a specific relation between their peak luminosity, bolometric light-curve rise time, and shock-breakout velocity. Given that the shock velocity during shock breakout is not measured, we expect a correlation, with a significant spread, between the rise time and the peak luminosity of these SNe. Here, we present a sample of 15 SNe IIn for which we have good constraints on their rise time and peak luminosity from observations obtained using the Palomar Transient Factory. We report on a possible correlation between the R-band rise time and peak luminosity of these SNe, with a false-alarm probability of 3%. Assuming that these SNe are powered by interaction, combining these observables and theory allows us to deduce lower limits on the shock-breakout velocity. The lower limits on the shock velocity we find are consistent with what is expected for SNe (i.e., ∼10{sup 4} km s{sup –1}). This supports the suggestion that the early-time light curves of SNe IIn are caused by shock breakout in a dense CSM. We note that such a correlation can arise from other physical mechanisms. Performing such a test on other classes of SNe (e.g., superluminous SNe) can be used to rule out the interaction model for a class of events.

  16. Latency of tone-burst-evoked auditory brain stem responses and otoacoustic emissions: Level, frequency, and rise-time effects

    PubMed Central

    Rasetshwane, Daniel M.; Argenyi, Michael; Neely, Stephen T.; Kopun, Judy G.; Gorga, Michael P.

    2013-01-01

    Simultaneous measurement of auditory brain stem response (ABR) and otoacoustic emission (OAE) delays may provide insights into effects of level, frequency, and stimulus rise-time on cochlear delay. Tone-burst-evoked ABRs and OAEs (TBOAEs) were measured simultaneously in normal-hearing human subjects. Stimuli included a wide range of frequencies (0.5–8 kHz), levels (20–90 dB SPL), and tone-burst rise times. ABR latencies have orderly dependence on these three parameters, similar to previously reported data by Gorga et al. [J. Speech Hear. Res. 31, 87–97 (1988)]. Level dependence of ABR and TBOAE latencies was similar across a wide range of stimulus conditions. At mid-frequencies, frequency dependence of ABR and TBOAE latencies were similar. The dependence of ABR latency on both rise time and level was significant; however, the interaction was not significant, suggesting independent effects. Comparison between ABR and TBOAE latencies reveals that the ratio of TBOAE latency to ABR forward latency (the level-dependent component of ABR total latency) is close to one below 1.5 kHz, but greater than two above 1.5 kHz. Despite the fact that the current experiment was designed to test compatibility with models of reverse-wave propagation, existing models do not completely explain the current data. PMID:23654387

  17. Development of the 50 TW laser for joint experiments with 1 MA z-pinches

    NASA Astrophysics Data System (ADS)

    Wiewior, P. P.; Ivanov, V. V.; Chalyy, O.

    2010-08-01

    A 50 TW high-intensity laser (aka "Leopard" laser) was developed for experiments with the 1 MA z-pinch generator at the University of Nevada, Reno. The laser produces short pulses of 0.35 ps; energy is 15 J. Long pulses are 1 ns; energy is 30 J. The output beam diameter is 80 mm. The Leopard laser applies chirped pulse amplification technology. The laser is based on the 130 fs Ti:Sapphire oscillator, Öffner-type stretcher, Ti:Sapphire regenerative amplifier, mixed Nd:glass rod and disk amplifiers, and vacuum grating compressor. An adaptive optics system ameliorates focusing ability and augments the repetition rate. Two beam terminals are available for experiments: in the vacuum chamber of the z-pinch generator (aka "Zebra"), and a laser-only vacuum chamber (aka "Phoenix" chamber). The Leopard laser coupled to the Zebra z-pinch generator is a powerful diagnostic tool for dense z-pinch plasma. We outline the status, design, architecture and parameters of the Leopard laser, and its coupling to Zebra. We present the methods of laser-based z-pinch plasma diagnostics, which are under development at the University of Nevada, Reno.

  18. Development of laser-based diagnostics for 1-MA z-pinch plasmas

    NASA Astrophysics Data System (ADS)

    Ivanov, V. V.; Hakel, P.; Mancini, R. C.; Wiewior, P.; Presura, R.; Kindel, J. M.; Shevelko, A. P.; Chalyy, O.; Astanovitskiy, A.; Haboub, A.; Altemara, S. D.; Papp, D.; Durmaz, T.

    2009-11-01

    The 50 TW Leopard laser coupled with the 1-MA Zebra generator was used for development of new diagnostics of z-pinch plasmas. Two plasma diagnostics are presented: an x-ray broadband backlighting for z-pinch absorption spectroscopy and parametric two-plasmon decay of the laser beam in dense z-pinch plasma. Implementation of new diagnostics on the Zebra generator and the first results are discussed. The absorption spectroscopy is based on backlighting of z-pinch plasma with a broadband x-ray radiation from a Sm laser plasma. Detailed analysis of the absorption spectra yields the electron temperature and density of z-pinch plasma at the non-radiative stage. The parametric two-plasmon decay of intensive laser radiation generates 3/2φ and 1/2φ harmonics. These harmonics can be used to derive a temperature of z-pinch plasma with the electron density near the quarter of critical plasma density.

  19. UV Laser Diagnostics of the 1-MA Z-pinch Plasmas

    SciTech Connect

    Altemara, S. D.; Ivanov, V. V.; Astanovitskiy, A. L.; Haboub, A.

    2009-01-21

    The 532 nm laser diagnostic set at the Zebra generator shows the details of the ablation and stagnation phases in cylindrical, planar, and star-like wire arrays but it cannot show the structure of the stagnated z-pinch and the implosion in small diameter loads, 1-3 mm in diameter. The absorption increment and the refraction angle of the 532 nm laser, when passing through the plasma, are too great to obtain quality images. An ultraviolet probing beam at the wavelength of 266 nm was developed to study small-diameter loads and to investigate the structure of the 1-MA z-pinch. The UV radiation has a much smaller absorption increment and refraction angles in plasmas than the 532 nm light and allows for better imaging of the z-pinch plasmas. Estimates showed that UV probing would be able to probe the high-density z-pinch plasma in experiments on the Zebra generator, and the early results of UV probing on the Zebra generator have shown promise.

  20. Calmodulin binds a highly extended HIV-1 MA protein that refolds upon its release.

    PubMed

    Taylor, James E; Chow, John Y H; Jeffries, Cy M; Kwan, Ann H; Duff, Anthony P; Hamilton, William A; Trewhella, Jill

    2012-08-01

    Calmodulin (CaM) expression is upregulated upon HIV-1 infection and interacts with proteins involved in viral processing, including the multifunctional HIV-1 MA protein. We present here the results of studies utilizing small-angle neutron scattering with contrast variation that, when considered in the light of earlier fluorescence and NMR data, show CaM binds MA in an extended open-clamp conformation via interactions with two tryptophans that are widely spaced in sequence and space. The interaction requires a disruption of the MA tertiary fold such that MA becomes highly extended in a long snakelike conformation. The CaM-MA interface is extensive, covering ~70% of the length of the MA such that regions known to be important in MA interactions with critical binding partners would be impacted. The CaM conformation is semiextended and as such is distinct from the classical CaM-collapse about short α-helical targets. NMR data show that upon dissociation of the CaM-MA complex, either by the removal of Ca(2+) or increasing ionic strength, MA reforms its native tertiary contacts. Thus, we observe a high level of structural plasticity in MA that may facilitate regulation of its activities via intracellular Ca(2+)-signaling during viral processing. PMID:22947870

  1. Temperature Evolution of a 1 MA Triple-Nozzle Gas-Puff Z-Pinch

    NASA Astrophysics Data System (ADS)

    de Grouchy, Philip; Banasek, Jacob; Engelbrecht, Joey; Qi, Niansheng; Atoyan, Levon; Byvank, Tom; Cahill, Adam; Moore, Hannah; Potter, William; Ransohoff, Lauren; Hammer, David; Kusse, Bruce; Laboratory of Plasma Studies Team

    2015-11-01

    Mitigation of the Rayleigh-Taylor instability (RTI) plays a critical role in optimizing x-ray output at high-energy ~ 13 keV using the triple-nozzle Krypton gas-puff at Sandia National Laboratory. RTI mitigation by gas-puff density profiling using a triple-nozzle gas-puff valve has recently been recently demonstrated on the COBRA 1MA z-pinch at Cornell University. In support of this work we investigate the role of shell cooling in the growth of RTI during gas-puff implosions. Temperature measurements within the imploding plasma shell are recorded using a 527 nm, 10 GW Thomson scattering diagnostic for Neon, Argon and Krypton puffs. The mass-density profile is held constant at 22 microgram per centimeter for all three puffs and the temperature evolution of the imploding material is recorded. In the case of Argon puffs we find that the shell ion and electron effective temperatures remain in equilibrium at around 1keV for the majority of the implosion phase. In contrast scattered spectra from Krypton are dominated by of order 10 keV effective ion temperatures. Supported by the NNSA Stewardship Sciences Academic Programs.

  2. Gas Puff Z-Pinches at 1-MA and 200-ns on COBRA

    NASA Astrophysics Data System (ADS)

    Hammer, David; Qi, Niansheng; Rosenberg, Elliott; Atoyan, Levon; Potter, William; Blesener, Kate; Cahill, Adam; Gourdain, Pierre-Alexandre; Greenly, John; Hoyt, Cad; Kusse, Bruce; Pikuz, Sergei; Schrafel, Peter; Shelkovenko, Tatiana

    2013-10-01

    We report 6-cm diameter, double-shell gas puff Z-pinch experiments at 1 MA on the COBRA pulsed power generator, in which the implosion dynamics in puff-on-puff load configurations with and without a wire on the pinch axis were studied. Diagnostics used included: Planar Laser Induced Fluorescence Analyzer for measuring initial density profiles of the gas puff; a Laser Shearing Interferometer and a Laser Wavefront Analyzer for density profiles in the implosion and pinch phases; fiber-coupled, gated visible-light spectrometers for radially resolved imploding plasma spectra; gated XUV cameras for implosion dynamics; filtered pinhole x-ray cameras for imaging x-ray emission; and a double-crystal x-ray spectrometer for axially resolved pinch plasma densities and temperatures. From these, we derived the implosion velocity, ion charge states and then the imploding plasma temperatures, obtained the time evolution of the imploding plasma sheath structure and Magnetic Rayleigh-Taylor instability, and observed the most stable implosion with light-ions (Ne) imploding on heavy-ions (Ar), unstable implosions with heavy-ions (Ar) imploding on light-ions (Ne), and tighter, denser and less hot pinch plasma with a wire on axis. Details of the results will be presented. Supported by NNSA under DOE Coop. Agreement DE- NA0001836.

  3. Rise-time response of nickel-foil-on-Kapton-substrate, hot-film, shear-stress sensors

    NASA Technical Reports Server (NTRS)

    Reda, Daniel C.

    1991-01-01

    An existing nickel-foil-on-Kapton-substrate sensor design was modified by including two heated elements in an attempt to minimize or reduce substrate conduction effects. The rise-time responses of the original and modified sensors were then investigated in unsteady flows of 0.5-1-s duration, consistent with flows encountered in wind-energy applications. The results obtained indicate a measurable degradation in transient performance due to the activation of the dynamic guard heater. Transient heat conduction within the substrate remains the limiting factor in such applications.

  4. Modification of water in a nanosecond diffuse discharge with fast electron preionization at a short voltage rise time

    NASA Astrophysics Data System (ADS)

    Orlovskii, Victor M.; Panarin, Victor A.; Shulepov, Mikhail A.

    2015-12-01

    The paper studies the dynamics of a nanosecond diffuse discharge with no additional preionization at a voltage rise time of less than 1 ns and its effect on drinking and distilled water. It is shown that the diffuse discharge is formed due to avalanche charge multiplication initiated by fast electrons and is sustained by secondary breakdown waves through ionized gas channels. Fourier transform infrared spectroscopy reveals that repeated exposure to the discharge changes the absorption spectra of drinking and distilled water such that the stretching vibration band of OH groups broadens and lacks clearly defined peaks. The water conductivity after irradiation increases. Probably, this is due to cluster rearrangement of water molecules.

  5. Electrophysiological aspects of the middle ear muscle reflex in the rat: latency, rise time and effect on sound transmission.

    PubMed

    van den Berge, H; Kingma, H; Kluge, C; Marres, E H

    1990-10-01

    The latency, the rise time and the influence of the acoustic reflex on sound transmission were investigated in the adult rat during ketamin anesthesia. This was done by recordings of the cochlear microphonics (CM) and electromyographic (EMG) recordings of the reflex responses of the tensor tympani muscle. The acoustic reflex was elicited by contralateral acoustic stimuli of which the intensity and frequency was varied. Ipsilaterally, the effect on sound transmission was determined by estimating the change in amplitude of the CM's of ipsilateral administered subliminal stimuli. It was shown that both the tensor tympani muscle and the stapedius muscle contribute in the reflex. The latency as well as the rise time of the reflex determined by CM recordings showed to be short (minimal values: 12 and 7 ms respectively). The mean latency of the tensor tympani muscle reflex, measured by EMG, was about 7 ms. The attenuation of 0.25-8 kHz tone bursts upto 115 dB SPL is limited to a mean maximum of 15 dB SPL. The maximal attenuation was shown to occur at 1 kHz. Frequencies above 2 kHz appeared to be the best elicitor of the middle ear muscle reflex.

  6. RISE TIME DELAY DISCRIMINATOR

    DOEpatents

    Johnstone, C.W.

    1959-09-29

    A pulse-height discriminator for generating an output pulse when the accepted input pulse is approximately at its maximum value is described. A gating tube and a negative bias generator responsive to the derivative of the input pulse and means for impressing the output of the bias generator to at least one control electrode of the gating tube are included.

  7. Development of a novel voltage divider for measurement of sub-nanosecond rise time high voltage pulses

    NASA Astrophysics Data System (ADS)

    Mitra, S.; Senthil, K.; Singh, S. K.; Kumar, Ranjeet; Sharma, Archana

    2016-02-01

    This paper is about the development of a copper sulphate based aqueous-electrolytic voltage divider for the measurement of high voltage pulses, 100 kV, with pulse widths of 1-2 ns and rise time <1 ns. Novel features are incorporated in the design of the divider, to meet the performance requirements for the application. Analytical calculations to justify design are described. Structural simulation of the divider is carried out using field wave simulation software to verify the effectiveness. A calibration procedure has been developed to calibrate the divider. Results obtained during calibration are subjected to statistical analysis to determine the confidence of measurement. Details of design, analysis, and simulation are described in this paper.

  8. Extracting Short Rise-Time Velocity Profiles with Digital Down-Shift Analysis of Optically Up-Converted PDV Data

    SciTech Connect

    Abel Diaz, Nathan Riley, Cenobio Gallegos, Matthew Teel, Michael Berninger, Thomas W. Tunnell

    2010-09-08

    This work describes the digital down-shift (DDS) technique, a new method of extracting short rise-time velocity profiles in the analysis of optically up-converted PDV data. The DDS technique manipulates the PDV data by subtracting a constant velocity (i.e., the DDS velocity νDDS) from the velocity profile. DDS exploits the simple fact that the optically up-converted data ride on top of a base velocity (ν0, the apparent velocity at no motion) with a rapid rise to a high velocity (νf) of a few km/s or more. Consequently, the frequency content of the signal must describe a velocity profile that increases from ν0 to ν0 + νf. The DDS technique produces velocity reversals in the processed data before shock breakout when ν0 < νDDS < ν0 + νf. The DDS analysis process strategically selects specific DDS velocities (velocity at which the user down shifts the data) that produce anomalous reversals (maxima and/or minima), which are predictable and easy to identify in the mid-range of the data. Additional analysis determines when these maxima and minima occur. By successive application of the DDS technique and iterative analysis, velocity profiles are extracted as time as a function of velocity rather than as a function of time as it would be in a conventional velocity profile. Presented results include a description of DDS, velocity profiles extracted from laser-driven shock data with rise times of 200 ps or less, and a comparison with other techniques.

  9. The Lake Bosumtwi Drilling Project: A 1 Ma West African Paleoclimate Record

    NASA Astrophysics Data System (ADS)

    Peck, J. A.; Heil, C.; King, J. W.; Scholz, C. A.; Shanahan, T. M.; Overpeck, J. T.; Fox, P. A.; Amoako, P. Y.; Forman, S. L.; Koeberl, C.; Milkereit, B.

    2005-12-01

    Lake Bosumtwi occupies a 1.07 Ma impact crater located in Ghana, West Africa centered at 06*32'N and 01*25'W. This 78 m deep, hydrologically-closed lake has a water budget extremely sensitive to the precipitation/evapotranspiration balance and is located in the path of the seasonal migration of the ITCZ. Therefore, Lake Bosumtwi is ideally situated to provide a long record of change in North African monsoon strength. In addition, the stratified water column allows for the preservation of finely-laminated sediments and the potential for high-resolution (annual) paleoclimate reconstruction. Using the GLAD800 lake drilling system, five drill sites were occupied along a water-depth transect in order to facilitate the reconstruction of the lake level history. At these five sites, a total of 14 separate holes were drilled yielding a total sediment recovery of 1,833 m. The shallow water drill sites consist of alternating laminated lacustrine mud (deepwater environment), moderately-sorted sand (nearshore beach environment) and sandy gravel (fluvial or lake marginal environments). These sediment cores and seismic reflection profiles are being used to construct a basin-wide stratigraphic framework, in order to extend further back in time the present Bosumtwi lake level histories obtained from highstand terraces and short piston cores. At a deep water site, the complete 1 Ma lacustrine stratigraphic section was recovered in 294 m deep holes that ended in impact-glass bearing, accretionary lapilli fallout representing the initial days of sedimentation. The lowermost lacustrine sediment is a bioturbated, light-gray mud with abundant gastropod shells indicating that a shallow-water oxic lake environment was established in the crater. Much of the overlying 294 m of mud is laminated thus these sediment cores will provide a unique 1 million year record of tropical African climate change. Two contrasting litholgies identified in the dated, upper part of the deep water drill hole

  10. Scaling of Radiation Parameters of Planar and Compact Cylindrical Wire Arrays at the 1 MA Zebra Generator

    SciTech Connect

    Williamson, K. M.; Kantsyrev, V. L.; Safronova, A. S.; Esaulov, A. A.; Shrestha, I.; Ouart, N. D.; Yilmaz, M. F.; Osborne, G. C.; Weller, M. E.; Shlyaptseva, V.; Chuvatin, A. S.

    2009-01-21

    Analysis is presented on scaling of radiated x-ray power, energy and implosion timing of single planar wire arrays (SPWA), double planar wire array (DPWA), and compact cylindrical wire array (CCWA) loads (diameter is 3 and 6 mm) of Mo and W with respect to current peak (0.8-1.4 MA), mass and array dimensions at 100 ns current pulse. Such scaling investigations are important for understanding the potential of these loads as an ICF radiation source{sup 7}. These data are used to identify promising directions to pursue with regard to highest x-ray output, smallest load size, and most consistent shot-to-shot performance. It is shown that W SPWA and DPWA total energy yield and peak power increased near-quadratically with current. DPWA scans of inter-planar gaps from 1.5 mm to 9 mm show an output maximum at 1.5 mm with decreasing output for 6 mm and 9 mm. A DPWA width scan shows that radiation yields decrease slowly as the width is decreased, which may allow for more compact loads without significant sacrifice to the output radiation. A mass scan of several W loads show that the implosion timing increases with mass.

  11. High-voltage isolation transformer for sub-nanosecond rise time pulses constructed with annular parallel-strip transmission lines.

    PubMed

    Homma, Akira

    2011-07-01

    A novel annular parallel-strip transmission line was devised to construct high-voltage high-speed pulse isolation transformers. The transmission lines can easily realize stable high-voltage operation and good impedance matching between primary and secondary circuits. The time constant for the step response of the transformer was calculated by introducing a simple low-frequency equivalent circuit model. Results show that the relation between the time constant and low-cut-off frequency of the transformer conforms to the theory of the general first-order linear time-invariant system. Results also show that the test transformer composed of the new transmission lines can transmit about 600 ps rise time pulses across the dc potential difference of more than 150 kV with insertion loss of -2.5 dB. The measured effective time constant of 12 ns agreed exactly with the theoretically predicted value. For practical applications involving the delivery of synchronized trigger signals to a dc high-voltage electron gun station, the transformer described in this paper exhibited advantages over methods using fiber optic cables for the signal transfer system. This transformer has no jitter or breakdown problems that invariably occur in active circuit components.

  12. Green`s function for a switched plasma medium and a perturbation technique for the study of wave propagation in a transient plasma with a small rise time

    SciTech Connect

    Kalluri, D.K.

    1996-12-31

    The main effect of switching a medium (creating a temporal discontinuity in the properties of a medium) is the splitting of the source (incident) wave into new waves whose frequencies are different. Lightning induced effects in the ionosphere cause a temporary enhancement of ionization. Such transient plasmas have a time-varying plasma frequency {omega}{sub p} (t) with a rise time T{sub r}. If the period t{sub 0} of a source wave existing before the transient effect begins is much larger than the rise time, the ionization change may be idealized as a sudden switching of the medium. The solution to this initial value problem with a step-change in the electron density profile is known and this profile will be considered as a reference profile. The topic of this paper is the solution of the initial value problem when t{sub 0} is comparable to the rise time T{sub r}. The initial motivation for investigating the problem is given below. There is considerable interest in the ionospheric physics community to investigate the recently discovered Sprites phenomenon which are red emissions in the lower D region induced by the lightning discharges from a cloud to the ground. The preliminary indications are that the Sprite is a plasma with electron density enhanced by about 10{sup 1} to 10{sup 3}/cc in a rise time of about 100 {micro}s.

  13. Summary of Sonic Boom Rise Times Observed During FAA Community Response Studies over a 6-Month Period in the Oklahoma City Area

    NASA Technical Reports Server (NTRS)

    Maglieri, Domenic J.; Sothcott, Victor E.

    1990-01-01

    The sonic boom signature data acquired from about 1225 supersonic flights, over a 6-month period in 1964 in the Oklahoma City area, was enhanced with the addition of data relating to rise times and total signature duration. These later parameters, not available at the time of publication of the original report on the Oklahoma City sonic boom exposures, are listed in tabular form along with overpressure, positive impulse, positive duration, and waveform category. Airplane operating information along with the surface weather observations are also included. Sonic boom rise times include readings to the 1/2, 3/4, and maximum overpressure values. Rise time relative probabilities for various lateral locations from the ground track of 0, 5, and 10 miles are presented along with the variation of rise times with flight altitude. The tabulated signature data, along with corresponding airplane operating conditions and surface and upper level atmospheric information, are also available on electronic files to provide it in the format for more efficient and effective utilization.

  14. Sedimentary architecture of the Bohai Sea China over the last 1 Ma and implications for sea-level changes

    NASA Astrophysics Data System (ADS)

    Shi, Xuefa; Yao, Zhengquan; Liu, Qingsong; Larrasoaña, Juan Cruz; Bai, Yazhi; Liu, Yanguang; Liu, Jihua; Cao, Peng; Li, Xiaoyan; Qiao, Shuqing; Wang, Kunshan; Fang, Xisheng; Xu, Taoyu

    2016-10-01

    Sedimentary architecture dominated by transgression-regression cycles in the shallow Bohai shelf region contains information about global sea-level, climate and local tectonics. However, previous studies of transgression-regression cycles in this region at orbital timescales that extend back to the early Pleistocene are sparse, mainly because of the shortage of well-dated long cores. Although transgression-regression sedimentary cycles in the region have been interpreted in terms of local tectonics, sea-level, and climate change, the detailed structure of marine transgressions and their significance for Quaternary global sea-level variations remains to be examined. In this study, we present an integrated sedimentological, geochemical and paleontological study of a 212.4 m (∼1 Ma) core (BH08) recovered from the Bohai Sea, China, for which an astronomically-based age model is available. Correspondence between marine-terrestrial sedimentary cycles and global sea-level fluctuations suggests that stacking of marine and terrestrial sediments was driven mainly by glacio-eustatic sea-level fluctuations in a context in which tectonic subsidence was largely balanced by sediment supply over the last ∼1 Ma. We report a dominant 100-kyr cycle beginning at ∼650 ka, which reflects the worldwide influence of the mid-Pleistocene transition (MPT) in sea-level records. We find that neritic deposits after the MPT were relatively thicker than before the MPT, which indicates an important control of the MPT on sedimentary architecture through lengthening of the duration of sea-level highstands.

  15. Microfossil Records and Shifts of Paleo-Kuroshio Current in the Nankai Trough since last 1 Ma

    NASA Astrophysics Data System (ADS)

    Su, X.; Duan, X.; Ling, L.; Chen, F.

    2014-12-01

    Kuroshio Current plays an important role in the oceanographic and climatic change in the West Pacific Ocean. Nearly few detailed record documented its long term variation history extending to middle Pleistocene period by previous studies. During Intergrated Ocean Drilling Exp. 315 in the Nankai Trough, a 100 m long sediment sequence in the upper part of Hole C0002D, which contains relative abundant calcareous fossils and with an age of Middle to late Pleistocene (1 Ma) was recovered. Age constrain for the sequences was based mainly on calcareous nannofossil biostratigraphy in combine with a few of paleonmagnetic stratigraphcial data (Expedition 315 Scientists, 2009) and plankton foraminiferal data (G. ruber (pink). Date sets of UK37 and plankton foraminiferal oxygen isotope were analyzed to constrain records of glacial-interglacial cycles, surface paleo-temperature (SST) and paleon-salinity (SSS). Records of these microfossil proxies vary in response to glacial-interglacial changes during the last 1 Ma. These records indicate that this region had be dominated by paleo-Kuroshio Current during five periods (MIS17, MIS13, MIS7, MIS5 and MIS1). The possible influence of the Northen Pacific Center Water Mass was seen during MIS16 and MIS11. Ref.: Expedition 315 Scientists, 2009. Expedition 315 Site C0002. In Kinoshita, M., Tobin, H., Ashi, J., Kimura, G., Lallemant, S., Screaton, E.J., Curewitz, D., Masago, H., Moe, K.T., and the Expedition 314/315/316 Scientists, Proc. IODP, 314/315/316: Washington, DC (Integrated Ocean Drilling Program Management International, Inc.). doi:10.2204/iodp.proc.314315316.124.2009

  16. Dating the Homo erectus bearing travertine from Kocabaş (Denizli, Turkey) at at least 1.1 Ma

    NASA Astrophysics Data System (ADS)

    Lebatard, Anne-Elisabeth; Alçiçek, M. Cihat; Rochette, Pierre; Khatib, Samir; Vialet, Amélie; Boulbes, Nicolas; Bourlès, Didier L.; Demory, François; Guipert, Gaspard; Mayda, Serdar; Titov, Vadim V.; Vidal, Laurence; de Lumley, Henry

    2014-03-01

    Since its discovery within a travertine quarry, the fragmentary cranium of the only known Turkish Homo erectus, the Kocabaş hominid, has led to conflicting biochronological estimations. First estimated to be ˜500 ka old, the partial skull presents a combination of archaic and evolved features that puts it as an intermediate specimen between the Dmanisi fossils (Homo georgicus) and the Chinese Zhoukoudian skulls (Homo erectus) respectively dated to 1.8 to ˜0.8 Ma. Here we present a multidisciplinary study combining sedimentological, paleontological and paleoanthropological observations together with cosmogenic nuclide concentration and paleomagnetic measurements to provide an absolute chronological framework for the Upper fossiliferous Travertine unit where the Kocabaş hominid and fauna were discovered. The 26Al/10Be burial ages determined on pebbles from conglomeratic levels framing the Upper fossiliferous Travertine unit, which exhibits an inverse polarity, constrains its deposition to before the Cobb Mountain sub-chron, that is between 1.22 and ˜1.5 Ma. The alternative match of the normal polarity recorded above the travertine with the Jaramillo subchron (lower limit 1.07 Ma) may also be marginally compatible with cosmogenic nuclides interpretation, thus the proposed minimum age of 1.1 Ma for the end of massive travertine deposition. The actual age of the fossils is likely to be in the 1.1-1.3 Ma range. This absolute date is in close agreement with the paleoanthropological conclusions based on morphometric comparisons implying that Kocabaş hominid belongs to the Homo erectus s.l. group that includes Chinese and African fossils, and is different from Middle and Upper Pleistocene specimens. Furthermore, this date is confirmed by the large mammal assemblage, typical of the late Villafranchian. Because it attests to the antiquity of human occupation of the Anatolian Peninsula and one of the waves of settlements out of Africa, this work challenges the current

  17. Rock magnetic signature of paleoenvironmental changes in the Izu Bonin rear arc over the last 1 Ma

    NASA Astrophysics Data System (ADS)

    Kars, Myriam; Vautravers, Maryline; Musgrave, Robert; Kodama, Kazuto

    2015-04-01

    During April and May 2014, IODP Expedition 350 drilled a 1806.5 m deep hole at Site U1437 in the Izu-Bonin rear arc, in order to understand, among other objectives, the compositional evolution of the arc since the Miocene and track the missing half of the subduction factory. The good recovery of mostly fine grained sediments at this site enables a high resolution paleontological and rock magnetic studies. Particularly, variations in magnetic properties and mineralogy are well documented. Natural remanent magnetization and magnetic susceptibility vary with a saw-tooth pattern. Routine rock magnetic measurements performed on about 400 samples in the first 120 meters of Hole U1437B showed that pseudo single domain to multidomain magnetite is the main carrier of the remanence. The origin of magnetite is likely detrital. The magnetic susceptibility variations depend on many factors (e.g. lithology, magnetic mineralogy, and also dilution by the carbonate matrix). The magnetic susceptibility is also used as a proxy, at first order, for magnetic minerals concentration. In order to highlight changes in magnetic minerals concentration, it's necessary to correct for the carbonate dilution effect. Onboard and onshore carbonate measurements by coulometry show that the carbonate content of the samples can be up to ~60%. About 70 samples were measured onshore. After correcting the susceptibility by the carbonate content measured on the same samples, it appears that the pattern of the magnetic susceptibility before and after correction is similar. Then the magnetic susceptibility variations do not result from carbonate dilution but reflect fluctuating influx of the detrital sediment component. The delta O18 variations obtained on foraminifers (N. dutertrei) show MIS 1 to MIS 25 over the studied interval covering the last 1 Ma (see Vautravers et al., this meeting). Rock magnetic properties, concentration and grain size variations of the magnetic minerals will be compared to

  18. Note: A rectangular pulse generator for 50 kV voltage, 0.8 ns rise time, and 10 ns pulse width based on polymer-film switch.

    PubMed

    Wu, Hanyu; Zhang, Xinjun; Sun, Tieping; Zeng, Zhengzhong; Cong, Peitian; Zhang, Shaoguo

    2015-10-01

    In this article, we describe a rectangular pulse generator, consisting of a polymer-film switch, a tri-plate transmission line, and parallel post-shaped ceramic resistor load, for 50-kV voltage, 0.8-ns rise time, and 10-ns width. The switch and resistors are arranged in atmospheric air and the transmission line can work in atmospheric air or in transformer oil to change the pulse width from 6.7 ns to 10 ns. The fast switching and low-inductance characteristics of the polymer-film switch ensure the fast rising wavefront of <1 ns. This generator can be applied in the calibration of nanosecond voltage dividers and used for electromagnetic pulse tests as a fast-rising current injection source. PMID:26521006

  19. Fault plane orientations of small earthquakes of the 1997 Umbria-Marche (Italy) seismic sequence from P-wave polarities and rise times

    NASA Astrophysics Data System (ADS)

    Filippucci, Marilena; de Lorenzo, Salvatore; Boschi, Enzo

    2006-07-01

    A two-step technique has been developed with the aim of retrieving the fault plane orientation of a small-magnitude earthquake. The technique uses a set of non-linear equations, which relate the rise times of first P waves to source parameters (source dimension L, dip δ and strike φ of the fault) and intrinsic Qp. At the first step of the technique, the inversion of P polarities provides two fault plane orientations for each focal mechanism solution. At the second step, the inversion of rise times is carried out to retrieve L and Qp by fixing δ and φ to the values of the fault plane orientation inferred at the first step. A robust analysis, based on the random deviates technique, allows us to evaluate if one fault plane exists which systematically better fits data and can be considered the `true' fault plane. A parameter is introduced to quantify the level of resolution of the `true' fault plane. A probabilistic approach, based on the assumption that errors on data are Gaussian distributed, allows us to a posteriori validate or reject the `true' fault plane. The technique has been applied to 47 small earthquakes (1.3 < ML < 3.9) occurred below the town of Sellano, during the 1997 Umbria-Marche (Central Italy) seismic crisis. The strike of the inferred fault planes is generally along the Apennine direction. Fault plane solutions can be mainly subdivided into two groups: a first group of SW-dipping faults and a second group of NE-dipping faults. These results agree with the present day knowledge of the fault systems in the area. An average Qp equal to 354 +/- 63 has been estimated, in agreement with previous attenuation studies.

  20. Measurement of intrinsic rise times for various L(Y)SO and LuAG scintillators with a general study of prompt photons to achieve 10 ps in TOF-PET.

    PubMed

    Gundacker, Stefan; Auffray, Etiennette; Pauwels, Kristof; Lecoq, Paul

    2016-04-01

    The coincidence time resolution (CTR) of scintillator based detectors commonly used in positron emission tomography is well known to be dependent on the scintillation decay time (τd) and the number of photons detected (n'), i.e. CTR proportional variant √τd/n'. However, it is still an open question to what extent the scintillation rise time (τr) and other fast or prompt photons, e.g. Cherenkov photons, at the beginning of the scintillation process influence the CTR. This paper presents measurements of the scintillation emission rate for different LSO type crystals, i.e. LSO:Ce, LYSO:Ce, LSO:Ce codoped Ca and LGSO:Ce. For the various LSO-type samples measured we find an average value of 70 ps for the scintillation rise time, although some crystals like LSO:Ce codoped Ca seem to have a much faster rise time in the order of 20 ps. Additional measurements for LuAG:Ce and LuAG:Pr show a rise time of 535 ps and 251 ps, respectively. For these crystals, prompt photons (Cherenkov) can be observed at the beginning of the scintillation event. Furthermore a significantly lower rise time value is observed when codoping with calcium. To quantitatively investigate the influence of the rise time to the time resolution we measured the CTR with the same L(Y)SO samples and compared the values to Monte Carlo simulations. Using the measured relative light yields, rise- and decay times of the scintillators we are able to quantitatively understand the measured CTRs in our simulations. Although the rise time is important to fully explain the CTR variation for the different samples tested we determined its influence on the CTR to be in the order of a few percent only. This result is surprising because, if only photonstatistics of the scintillation process is considered, the CTR would be proportional to the square root of the rise time. The unexpected small rise time influence on the CTR can be explained by the convolution of the scintillation rate with the single photon time

  1. Measurement of intrinsic rise times for various L(Y)SO and LuAG scintillators with a general study of prompt photons to achieve 10 ps in TOF-PET.

    PubMed

    Gundacker, Stefan; Auffray, Etiennette; Pauwels, Kristof; Lecoq, Paul

    2016-04-01

    The coincidence time resolution (CTR) of scintillator based detectors commonly used in positron emission tomography is well known to be dependent on the scintillation decay time (τd) and the number of photons detected (n'), i.e. CTR proportional variant √τd/n'. However, it is still an open question to what extent the scintillation rise time (τr) and other fast or prompt photons, e.g. Cherenkov photons, at the beginning of the scintillation process influence the CTR. This paper presents measurements of the scintillation emission rate for different LSO type crystals, i.e. LSO:Ce, LYSO:Ce, LSO:Ce codoped Ca and LGSO:Ce. For the various LSO-type samples measured we find an average value of 70 ps for the scintillation rise time, although some crystals like LSO:Ce codoped Ca seem to have a much faster rise time in the order of 20 ps. Additional measurements for LuAG:Ce and LuAG:Pr show a rise time of 535 ps and 251 ps, respectively. For these crystals, prompt photons (Cherenkov) can be observed at the beginning of the scintillation event. Furthermore a significantly lower rise time value is observed when codoping with calcium. To quantitatively investigate the influence of the rise time to the time resolution we measured the CTR with the same L(Y)SO samples and compared the values to Monte Carlo simulations. Using the measured relative light yields, rise- and decay times of the scintillators we are able to quantitatively understand the measured CTRs in our simulations. Although the rise time is important to fully explain the CTR variation for the different samples tested we determined its influence on the CTR to be in the order of a few percent only. This result is surprising because, if only photonstatistics of the scintillation process is considered, the CTR would be proportional to the square root of the rise time. The unexpected small rise time influence on the CTR can be explained by the convolution of the scintillation rate with the single photon time

  2. Sonic-boom measurements in the focus region during the ascent of Apollo 17. [maximum positive overpressure, positive impulse, signature duration, and bow-shock rise time

    NASA Technical Reports Server (NTRS)

    Henderson, H. R.; Hilton, D. A.

    1974-01-01

    Sonic-boom pressure signatures recorded during the ascent phase of Apollo 17 are presented. The measurements were obtained onboard six U.S. Navy ships positioned along the ground track of the spacecraft vehicle in the area of expected focus resulting from the flight path and acceleration of the vehicle. Tracings of the measured signatures are presented along with values of the maximum positive overpressure, positive impulse, signature duration, and bowshock rise time. Also included are brief descriptions of the ships and their location, the deployment of the sonic-boom instrumentation, flight profiles and operating conditions for the launch vehicle and spacecraft, surface-weather and sea-state information at the measuring sites, and high-altitude weather information for the general measurement areas. Comparisons of the measured and predicted sonic-boom overpressures for the Apollo 17 mission are presented. The measured data are also compared with data from the Apollo 15 and 16 missions and data from flight test programs of various aircraft.

  3. Development of the N1–P2 auditory evoked response to amplitude rise time and rate of formant transition of speech sounds

    PubMed Central

    Carpenter, Allen L.; Shahin, Antoine J.

    2013-01-01

    We investigated the development of weighting strategies for acoustic cues by examining the morphology of the N1–P2 auditory evoked potential (AEP) to changes in amplitude rise time (ART) and rate of formant transition (RFT) of consonant–vowel (CV) pairsin4–6-year olds and adults. In the AEP session, individuals listened passively to the CVs /ba/, /wa/, and a /ba/ with a superimposed slower-rising /wa/ envelope (/ba/wa). In the behavioral session, individuals listened to the same stimuli and judged whether they heard a /ba/ or /wa/. We hypothesized that a developmental shift in weighting strategies should be reflected in a change in the morphology of the N1–P2 AEP. In 6-year olds and adults, the N1–P2 amplitude at the vertex reflected a change in RFT but not in ART. In contrast, in the 4–5-year olds, the vertex N1–P2 did not show specificity to changes in ART or RFT. In all groups, the N1–P2 amplitude at channel C4 (right hemisphere) reflected a change in ART but not in RFT. Behaviorally, 6-year olds and adults predominately utilized RFT cues (classified /ba/wa as /ba/) during phonetic judgments, as opposed to 4–5-year olds which utilized both cues equally. Our findings suggest that both ART and RFT are encoded in the auditory cortex, but an N1–P2 shift toward the vertex following age 4–5 indicates a shift toward an adult-like weighting strategy, such that, to utilize RFT to a greater extent. PMID:23570734

  4. Modeling of K-Shell Al and Mg and L-Shell Mo Radiation from Compact Cylindrical Wire Array Plasmas Produced on the 1 MA UNR Zebra Generator

    SciTech Connect

    Yilmaz, M. F.; Safronova, A. S.; Esaulov, A. A.; Kantsyrev, V. L.; Quart, N. D.; Williamson, K. M.; Shrestha, I.

    2009-01-21

    K-shell radiation of Al and Mg and L-shell radiation of Mo from implosions of compact cylindrical wire arrays (CCWA) on the 1 MA UNR Zebra generator was studied. Specifically, radiation from implosions of 3 and 6 mm CCWA with (16-24) Al-5052 (95% Al and 5% Mg) and Al-5052 (97.5% Al and 2.5% Mg) and Mo wires was analyzed using the full set of diagnostics: PCD and current signals, and X-ray pinhole images and spectra. Previously developed non-LTE models were applied to model spatially resolved time integrated as well as time-gated spatially integrated spectra from Al, Mg, and Mo plasmas. Derived electron temperature and density spatial gradients as well as percentage of radiating mass were studied and compared. In addition, the novel Wire Dynamics Model (WDM) was used to analyze the implosion dynamics of compact wire array loads.

  5. Detailed bathymetry and magnetic anomaly in the Central Ryukyu Arc, Japan: implications for a westward shift of the volcanic front after approximately 2.1 Ma

    NASA Astrophysics Data System (ADS)

    Sato, Taichi; Oda, Hirokuni; Ishizuka, Osamu; Arai, Kohsaku

    2014-12-01

    Detailed bathymetry and magnetic anomalies in the southern part of the Central Ryukyu Arc reveal recent volcanic structures in a southwestward extension of the active volcanic front of the Ryukyu Arc. A line of bathymetric highs running subparallel to this recent volcanic front was observed approximately 20 km to the east. A set of small, sharply defined magnetic anomalies extends southward from this line of bathymetric highs to the islands Kume-jima and Aguni-jima, suggesting the former existence of an ancient volcanic front. The ages of volcanic rocks from these islands indicate that magmatic activity along the ancient volcanic front continued until at least approximately 2.1 Ma. The presence of magnetic anomalies between the two volcanic fronts suggests that the volcanic front has moved gradually westward. This shift can be explained by the termination of asthenospheric upwelling and/or the rapid retreat of the Ryukyu Trench after its change in subduction direction.

  6. Detailed bathymetry and magnetic anomaly inthe Central Ryukyu Arc, Japan: implications for a westward shift of the volcanic front after ~2.1 Ma

    NASA Astrophysics Data System (ADS)

    Sato, T.; Oda, H.; Ishizuka, O.; Arai, K.

    2014-12-01

    Detailed bathymetry and magnetic anomalies in the southern part of the Central Ryukyu Arc reveal recent volcanic structures in a southwestward extension of the active volcanic front of the Ryukyu Arc. A line of bathymetric highs running subparallel to this recent volcanic front was observed ~20 km to the east. A set of small, sharply defined magnetic anomalies extends southward from this line of bathymetric highs to the islands Kume-jima and Aguni-jima, suggesting the former existence of an ancient volcanic front. The ages of volcanic rocks from these islands indicate that magmatic activity along the ancient volcanic front continued until at least ~2.1 Ma. The presence of magnetic anomalies between the two volcanic fronts suggests that the volcanic front has moved gradually westward. This shift can be explained by the termination of asthenospheric upwelling and/or the rapid retreat of the Ryukyu Trench after its change in subduction direction.

  7. Analysis of Compact Cylindrical Wire Array Implosions with Brass and also by Alternating Brass and Al wires on the 1-MA COBRA Generator

    SciTech Connect

    Ouart, N. D.; Yilmaz, M. F.; Safronova, A. S.; Kantsyrev, V. L.; Esaulov, A. A.; Williamson, K. M.; Osborne, G. C.; Shrestha, I.; Weller, M. E.; McBride, R. D.; Knapp, P. F.; Bell, K. S.; Pikuz, S. A.; Shelkovenko, T. A.; Greenly, J. B.; Hammer, D. A.; Kusse, B. R.

    2009-01-21

    Implosions from compact cylindrical wire arrays (CCWA) with mid-Z and low-Z wires were carried out on the 1-MA COBRA generator at Cornell University. In particular, the CCWA used either Brass 310 (70% Cu, 30% Zn) wires or a combination of Brass 310 and Al 5056 (95% Al, 5% Mg) wires arranged in an alternating pattern. A total of 16 wires were used on either a 6 or 4 mm diameter array. The diagnostic suite included a bolometer, fast x-ray detectors, a time-integrated spectrometer, and a streak camera. A higher energy output was observed from bolometer measurements when alternating the brass and Al wires compared to using only the brass wires. This study will focus mainly on the spectroscopy of the brass and alternating brass and Al CCWA by applying the non-LTE kinetic models of Cu and Zn to account for the L-shell radiation. The resulting plasma parameters, electron density and electron temperature, will be discussed and compared for the CCWA with only brass wires and alternating brass and Al wires. The simulations with the novel Wire Ablation Dynamics Model that account for wire ablation will be performed to analyze the differences in implosion dynamics of the uniform and alternating compact cylindrical arrays.

  8. Study of Ablation and Implosion Stages of 1-MA Wire Array Z-Pinch using X-ray Laser-Based Backlighting

    NASA Astrophysics Data System (ADS)

    Anderson, Austin; Ivanov, Vladimir; Papp, Daniel; Talbot, Bjorn; Astanovitskiy, Alexey

    2013-10-01

    The ablation and implosion stages of wire array z-pinches were studied using laser-based x-ray imaging at the 1-MA Zebra pulse power generator at the University of Nevada, Reno. X-ray backlighting at the wavelength of 6.65 Å was provided by hitting a Si target with the 50 TW Leopard laser. Laser-based radiography allows flexibility in both the timing and the position of the x-ray source. The issue of the method is the small energy of the laser pulse compared to radiation of the Z pinch. A spherically bent quartz crystal can give spatial resolution <10 microns and spectral linewidth of the x-ray on the order of 10-4. X-ray imaging allows viewing of the dense core of plasma column during the ablation stage. Wires with diameters 7.6-15 were resolved in test shots. Images of the wire-array at the ablation stage are discussed. Work was supported by the DOE grant DE-SC0008824 and DOE/NNSA UNR grant DE-FC52-06NA27616.

  9. Spectroscopic modeling and comparison of radiation from X-pinches and wire arrays produced on the 1 MA pulsed power generator at UNR.

    SciTech Connect

    Yilmaz, M. Faith; Osborne, Glenn C.; Esaulov, Andrey A.; LePell, Paul David; Fedin, Dmitry; Kantsyrev, Victor Leonidovich; Coverdale, Christine Anne; Deeney, Christopher; Jones, Brent Manley; Ouart, Nicholas D.; Cowan, Thomas E.; Safronova, Alla S.

    2005-06-01

    X-ray spectra and images from Al (with 5% of Mg and some with 5% of NaF dopants) and Cu (pure and with 4% of Ni) wire arrays and X-pinches were accumulated in experiments on the 1 MA pulsed power generator at UNR. In particular, axially and radially resolved K-shell X-ray spectra of Al, Mg, and Na and L-shell X-ray spectra of Cu and Ni were recorded by a KAP crystal (in a spectral region from 6 to 15 Aring) through different slits from 50 mum to 3 mm. In addition, spatially integrated harder X-ray spectra were monitored by a LiF crystal. Non-LTE kinetic models of Al, Mg, and Na, and of Cu and Ni provided spatially resolved electron temperatures and densities for experiments with Al and Cu loads, respectively. Advantages of using alloys and dopants with small concentrations for spectroscopic plasma diagnostics will be presented. Dependence of the plasma's spatial structures, temperatures, and densities from wire material and load configurations, sizes, and masses will be discussed .

  10. Implosion dynamics and Spectroscopy of X-pinches and Wire arrays with doped Al wires on the UNR 1MA Z-pinch generator

    SciTech Connect

    Safronova, Alla; Kantsyrev, Victor; Esaulov, Audrey; Fedin, Dmitry; Ouart, Nicholas; Yilmaz, Fatih; Osborne, Glenn; Nalajala, Vidya; Pokala, Shivaji; Shrestha, Ishor; Astanovitsky, Alexey; Batie, Steve; LeGalloudec, Bruno; Cowan, Tom; LePell, David; Gradel, Josh

    2006-01-05

    The study of implosion dynamics and spectroscopy of X-pinches and wire arrays with Al wires alloyed or coated with other near-Z or higher-Z materials is discussed. In particular, X-pinches from two combined Al 5056 and Mo wires and composed from four identical Al 5056 (5%Mg) wires and Cu clad Al (90% Al and 10%Cu) are studied. In addition, wire arrays with Alumel wires (95% Ni and 5% Al) and with Al 5056 wires (uncoated) and coated with 5% NaF are investigated. Spatially-resolved and integrated x-ray spectral data and time integrated and time-gated pinhole x-ray images accumulated in these X-pinch and wire array experiments on the UNR 1MA Zebra generator are analyzed. Modeling of K-shell radiation from Mg provides K-shell plasma parameters for all Al 5056 wire experiments, whereas modeling of L-shell radiation from Ni, Cu, and Mo provide parameters for L-shell plasmas. The importance of using different materials or dopants for understanding of implosion dynamics of different wire materials is illustrated.

  11. The relationship between eruptive activity, flank collapse, and sea level at volcanic islands: A long-term (>1 Ma) record offshore Montserrat, Lesser Antilles

    NASA Astrophysics Data System (ADS)

    Coussens, Maya; Wall-Palmer, Deborah; Talling, Peter. J.; Watt, Sebastian. F. L.; Cassidy, Michael; Jutzeler, Martin; Clare, Michael A.; Hunt, James. E.; Manga, Michael; Gernon, Thomas. M.; Palmer, Martin. R.; Hatter, Stuart. J.; Boudon, Georges; Endo, Daisuke; Fujinawa, Akihiko; Hatfield, Robert; Hornbach, Matthew. J.; Ishizuka, Osamu; Kataoka, Kyoko; Le Friant, Anne; Maeno, Fukashi; McCanta, Molly; Stinton, Adam. J.

    2016-07-01

    Hole U1395B, drilled southeast of Montserrat during Integrated Ocean Drilling Program Expedition 340, provides a long (>1 Ma) and detailed record of eruptive and mass-wasting events (>130 discrete events). This record can be used to explore the temporal evolution in volcanic activity and landslides at an arc volcano. Analysis of tephra fall and volcaniclastic turbidite deposits in the drill cores reveals three heightened periods of volcanic activity on the island of Montserrat (˜930 to ˜900 ka, ˜810 to ˜760 ka, and ˜190 to ˜120 ka) that coincide with periods of increased volcano instability and mass-wasting. The youngest of these periods marks the peak in activity at the Soufrière Hills volcano. The largest flank collapse of this volcano (˜130 ka) occurred toward the end of this period, and two younger landslides also occurred during a period of relatively elevated volcanism. These three landslides represent the only large (>0.3 km3) flank collapses of the Soufrière Hills edifice, and their timing also coincides with periods of rapid sea level rise (>5 m/ka). Available age data from other island arc volcanoes suggest a general correlation between the timing of large landslides and periods of rapid sea level rise, but this is not observed for volcanoes in intraplate ocean settings. We thus infer that rapid sea level rise may modulate the timing of collapse at island arc volcanoes, but not in larger ocean-island settings.

  12. Experimental study of star-like and small-diameter wire-array z-pinches on the 1-MA Zebra generator

    SciTech Connect

    Ivanov, V. V.; Sotnikov, V. I.; Kindel, J. M.; Hakel, P.; Mancini, R. C.; Astanovitskiy, A. L.; Haboub, A.; Altemara, S. D.; Le Galloudec, B.; Nalajala, V.; Shevelko, A. P.; Kazakov, E. D.

    2009-01-21

    Star-like wire arrays and small-diameter (1-3 mm in diameter) cylindrical loads were tested in the 1-MA Zebra generator. Mitigation of plasma inhomogeneity was observed in the implosions of star-like loads, which consisted of multiple nested, cylindrical arrays aligned azimuthally such that the wires appear as linear array 'rays' extending from the axis of symmetry. The implosion in these loads is directed along the 'rays' of the star and cascades from wire to wire to the center to form moving plasma columns with smooth leading edges. Despite the low azimuthal symmetry, a star-like wire array produces a stable x-ray pulse with a high peak power and a short duration of 8-12-ns. This can be linked to the stabilization of instabilities due to the multiple nesting. X-ray generation and implosion dynamics in wire arrays 1-16 mm in diameter were investigated to find a transition between the regime with prevailing kinetic energy and 'non-kinetic' plasma heating. Loads 3-8 mm in diameter generate the highest x-ray power at the Zebra generator. The fall of x-ray power in 1-2-mm loads can be linked to the lack of kinetic energy. Laser probing diagnostics show the formation of 'necks' on the pinch during the bubble-like implosion. The energy balance provides the evidence of the enhanced plasma heating in z-pinches. Features of the implosions in small-diameter wire-arrays can help to identify the mechanisms of energy dissipation.

  13. Aperture of the northern and central Gulf of California since 9 to -1 Ma BP, using an instantaneous kinematic plate tectonics model

    NASA Astrophysics Data System (ADS)

    Gonzalez-Garcia, J.; Gonzalez-Ortega, J.

    2013-12-01

    The position of points over the earth surface is conveniently represented in a terrestrial (earth center fixed) reference frame, one that is rotating in some well defined way with the earth. In order to represent actual, past and future positions, we use the International Terrestrial Reference Frame, with kinematic plate tectonic models in a no-net rotation mode. Here we use the Pacific-Northamerica (PA-NA) plate motion model with Northamerica plate fixed. In our case, the actual shoreline of Mexico mainland is maintained fixed for visual purpose. We show the translation of the Baja California peninsula, traveling as PA-NA, since 9 Ma BP to 1 Ma AP. We made a 'calibration' of few kinematic plate tectonic models in PA-NA zone constraining the stable Mendocino Triple Junction (MTJ; 40.384°N ×2 km, 124.88°W +2, -4 km). Those models can be divided in two groups: space geodesy and geological. A preliminary result shows that geodesy models are a better representation of a constant kinematic plate tectonic motion, as compared with geological ones (using actual directions of transform faults, seafloor spreading anomalies with and without earthquake slip vectors). We select GEODVEL plate motion model, which uses four space geodesy techniques: VLBI, SLR, DORIS and GPS. The aperture of the northern and central Gulf of California is adjusted by the evolution of the MTJ and a 'virtual' southeastern end triple junction, which is not coincident with the Rivera Triple Junction. We also observe that GEODVEL is not well constrained at Guadalupe and Socorro islands, which are supposed to be part of Pacific plate, but with 2.5 and 7.0 mm/yr residual, respectively.

  14. Zircon U-Th-Pb dating using LA-ICP-MS: Simultaneous U-Pb and U-Th dating on the 0.1 Ma Toya Tephra, Japan

    NASA Astrophysics Data System (ADS)

    Ito, Hisatoshi

    2014-12-01

    Simultaneous U-Pb and U-Th zircon dating using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) was performed on the ~ 0.1 Ma Toya Tephra, Hokkaido, Japan. The method employs the concurrent measurement of 206Pb, 230Th, and 238U signals, which enables the determination of 238U-206Pb (U-Pb) and 238U-230Th (U-Th) ages simultaneously. The U-Pb ages revealed that the Toya Tephra contains zircons with ages that cluster at ~ 0.1 Ma (0.11 ± 0.01 Ma: error shown as 95% confidence level) and xenocrysts with ages > 2 Ma. Excluding zircons > 2 Ma, the U-Th method also gave an isochron age of ~ 0.1 Ma (108 ± 19 ka or 0.11 ± 0.02 Ma; error shown as 2σ). Therefore, both U-Pb and U-Th methods result in similar ages of ~ 0.1 Ma for the Toya Tephra, in agreement with the quartz TL age (104 ± 30 to 118 ± 30 ka) of Ganzawa and Ike (2011). It was revealed that the simultaneous U-Pb and U-Th zircon dating technique using LA-ICP-MS is easy to apply and is useful for Quaternary tephras in that it can give age information on the tephra itself and xenocrystic zircons in a quick and cost-effective manner. The double dating technique employed here has the merit that zircons yielding Quaternary U-Pb ages can be immediately cross-checked by the U-Th method. It was also revealed that the Toya Tephra magma crystallized zircons and experienced eruptions instantaneously at ~ 0.1 Ma, which is an important implication to decipher magmatic and eruptive processes for caldera-forming large volcanic systems.

  15. Thermoreflectance imaging of sub 100 ns pulsed cooling in high-speed thermoelectric microcoolers

    NASA Astrophysics Data System (ADS)

    Vermeersch, Bjorn; Bahk, Je-Hyeong; Christofferson, James; Shakouri, Ali

    2013-03-01

    Miniaturized thin film thermoelectric coolers have received considerable attention as potential means to locally address hot spots in microprocessors. Given the highly dynamic workload in complex integrated circuits, the need arises for a thorough understanding of the high-speed thermal behavior of microcoolers. Although some prior work on transient Peltier cooling in pulsed operation is available, these studies mostly focus on theoretical modeling and typically deal with relatively large modules with time constants well into the millisecond range. In this paper, we present an extensive experimental characterization of 30×30 μm2 high-speed coplanar SiGe superlattice microcoolers subjected to 300 ns wide current pulses at ≈ 300 kHz repetition rate. Using thermoreflectance imaging microscopy, we obtain 2D maps of the transient surface temperature and constituent Peltier and Joule components over the 50-750 ns time range with submicron spatial and 50 ns temporal resolutions. Net cooling of 1 K-1.5 K is achieved within 100-300 ns, well over an order of magnitude faster compared to previous reports on microcoolers in high-speed operation. We also point out ambiguities in separating Peltier and Joule signals during the device turn-off. Overall, our measurements provide substantial insight into ultrafast turn-on and turn-off dynamics in thin film thermoelectrics.

  16. Measurement of DNA Translocation Dynamics in a Solid-State Nanopore at 100 ns Temporal Resolution.

    PubMed

    Shekar, Siddharth; Niedzwiecki, David J; Chien, Chen-Chi; Ong, Peijie; Fleischer, Daniel A; Lin, Jianxun; Rosenstein, Jacob K; Drndić, Marija; Shepard, Kenneth L

    2016-07-13

    Despite the potential for nanopores to be a platform for high-bandwidth study of single-molecule systems, ionic current measurements through nanopores have been limited in their temporal resolution by noise arising from poorly optimized measurement electronics and large parasitic capacitances in the nanopore membranes. Here, we present a complementary metal-oxide-semiconductor (CMOS) nanopore (CNP) amplifier capable of low noise recordings at an unprecedented 10 MHz bandwidth. When integrated with state-of-the-art solid-state nanopores in silicon nitride membranes, we achieve an SNR of greater than 10 for ssDNA translocations at a measurement bandwidth of 5 MHz, which represents the fastest ion current recordings through nanopores reported to date. We observe transient features in ssDNA translocation events that are as short as 200 ns, which are hidden even at bandwidths as high as 1 MHz. These features offer further insights into the translocation kinetics of molecules entering and exiting the pore. This platform highlights the advantages of high-bandwidth translocation measurements made possible by integrating nanopores and custom-designed electronics. PMID:27332998

  17. Measurement of DNA Translocation Dynamics in a Solid-State Nanopore at 100 ns Temporal Resolution.

    PubMed

    Shekar, Siddharth; Niedzwiecki, David J; Chien, Chen-Chi; Ong, Peijie; Fleischer, Daniel A; Lin, Jianxun; Rosenstein, Jacob K; Drndić, Marija; Shepard, Kenneth L

    2016-07-13

    Despite the potential for nanopores to be a platform for high-bandwidth study of single-molecule systems, ionic current measurements through nanopores have been limited in their temporal resolution by noise arising from poorly optimized measurement electronics and large parasitic capacitances in the nanopore membranes. Here, we present a complementary metal-oxide-semiconductor (CMOS) nanopore (CNP) amplifier capable of low noise recordings at an unprecedented 10 MHz bandwidth. When integrated with state-of-the-art solid-state nanopores in silicon nitride membranes, we achieve an SNR of greater than 10 for ssDNA translocations at a measurement bandwidth of 5 MHz, which represents the fastest ion current recordings through nanopores reported to date. We observe transient features in ssDNA translocation events that are as short as 200 ns, which are hidden even at bandwidths as high as 1 MHz. These features offer further insights into the translocation kinetics of molecules entering and exiting the pore. This platform highlights the advantages of high-bandwidth translocation measurements made possible by integrating nanopores and custom-designed electronics.

  18. Hydrothermal Mineral Deposits From a Young (0.1Ma) Abyssal Hill on the Flank of the Fast-Spreading East Pacific Rise

    NASA Astrophysics Data System (ADS)

    Benjamin, S. B.; Haymon, R. M.

    2004-12-01

    It has been estimated from heat flow measurements that at least 40% of the total hydrothermal heat lost from oceanic lithosphere is removed from 0.1-5 Ma abyssal hill terrain on mid-ocean ridge flanks. Despite the large magnitude of estimated hydrothermal heat loss from young abyssal hills, little is known about characteristics of hydrothermal vents and mineral deposits in this setting. This study describes the first abyssal hill hydrothermal samples to be collected on the flank of a fast-spreading ridge. The mineral deposits were discovered at "Tevnia Site" on the axis-facing fault scarp of an abyssal hill, located on ˜0.1 Ma lithosphere ˜5 km east of the East Pacific Rise (EPR) axis at 10\\deg 20'N. Observations of Galatheid crabs, "dandelion" siphonophores, and colonies of dead, yet still intact, Tevnia worm tubes at this site during Alvin dives in 1994 suggests relatively recent hydrothermal activity. The deposits are friable hydrothermal precipitates incorporating volcanic clasts brecciated at both the micro and macro scales. The petrographic sequence of brecciation, alteration, and cementation exhibited by the samples suggests that they formed from many pulses of hydrothermal venting interspersed with, and perhaps triggered by, repeated tectonic events as the abyssal hill was uplifted and moved off-axis (see also Haymon et al., this session). Observed minerals include x-ray amorphous opaline silica and Fe-oxide phases, crystalline Mn-oxides (birnessite and todorokite), an irregularly stratified mixed layer nontronite-celadonite, and residual calcite in sediment-derived microfossils incorporated into the breccia matrix. This mineral assemblage suggests that the deposits precipitated from moderately low-temperature (<140\\deg C) fluids, enriched in K, Fe, Si, and Mn, with a near-neutral pH. The presence of tubeworm casings at the site is evidence that the hydrothermal fluids carried H2S, however no metal sulfide phases were identified in the samples. Although

  19. High speed electrostatic photomultiplier tube for the 1.06 micrometer wavelength. Cup and slat dynode chain combined with flat cathode and coax output produces 0.25 nsec rise time

    NASA Technical Reports Server (NTRS)

    Sparks, S. D.

    1973-01-01

    The Varian cup and slat dynode chain was modified to have a flat cathode. These modifications were incorporated in an all-electrostatic photomultiplier tube having a rise time of 0.25 n sec. The tube delivered under the contract had a flat S-20 opaque cathode with a useful diameter of 5 mm. The design of the tube is such that a III to V cathode support is mounted in place of the existing cathode substrate. This cathode support is designed to accept a transferred III to V cathode and maintain the cathode surface in the same position as the S-20 photocathode.

  20. Calcareous nannofossil evidence for Marine Isotope Stage 31 (1 Ma) in the AND-1B Core, ANDRILL McMurdo Ice Shelf Project (Antarctica).

    NASA Astrophysics Data System (ADS)

    Villa, G.; Persico, D.; Wise, S. W.; Gadaleta, A.

    2009-04-01

    , Thoracosphaera spp.. The presence of several Tertiary reworked species and rare Cretaceous reworked taxa are interpreted in terms of provenance. As the lower temperature limit for living calcareous nannoplankton is about 2.5°C, the presence of nannofossils from 86 to 96 mbsf, though rare, is an indication of ice-free and sea surface temperatures warmer than today, in the Ross Sea. The presence of numerous volcaniclastic units and biosiliceous sediments from 86.6 to 92.5 mbsf indicate an extended period of open-water conditions with no sea ice, beyond the calving line. An 40Ar/39Ar age of 1.014 ± 0.004 Ma on pumice at 85.50 mbsf confirms the age assignment given by diatom biostratigraphy (1.07 Ma) for this interval. Accordingly, the short normal magnetozone between 84.97 and 91.13 mbsf is correlated with the Jaramillo Subchron (C1r.1n) (Wilson et al., 2007). The presence of nannofossil in the biogenic interglacial sediments is consistent with warm episode of surface waters and open marine conditions during the Jaramillo subchron, at ~1 Ma, which corresponds with Marine isotope stage (MIS-31) (Naish et al., 2007). The "superinterglacial" associated with MIS 31 was the last significant warm interglacial of the obliquity-dominated world, and may represent a precursor to the high-amplitude eccentricity-dominated cycles that followed the mid-Pleistocene climate shift. Climate proxies from other studies from the Southern Ocean at ODP Site 1165 (Villa et al., 2008), at ODP Site 1094 (Scherer et al., 2008), and from the Antarctic margin in a shelly carbonate sequence at Cape Roberts 1 (Villa and Wise, 1998; Scherer et al., 2008) also support the idea of a warming event during this time, suggesting that it was extended around the Antarctic Continent. This in turn implies a total or partial collapse of McMurdo Ice Shelf and a concurrent shift or temporary dissipation of the Polar Front (Antarctic Convergence) and Antarctic Divergence that currently serve as barriers to the influx of

  1. Superconducting, fast rise-time voltage source

    SciTech Connect

    Lumley, R.M.

    1983-01-25

    A pulse generator comprises a toroid of a superconducting material such as niobium on a glass or ceramic substrate. A cryogenic source such as liquid helium cools the toroid to within a few degrees of absolute zero and a perpetually circulatory current is set up in the toroid. A laser beam is fired at the toroid to cause localized heating and the resultant current drop due to the material resistance causes an output pulse to be induced in an adjacent current winding.

  2. Rugged calorimeter with a fast rise time

    SciTech Connect

    McMurtry, W.M.; Dolce, S.R.

    1980-01-01

    An intrinsic 1-mil-thick gold foil calorimeter has been developed which rises to 95% of the energy deposited in less than 2 microseconds. This calorimeter is very rugged, and can withstand rough handling without damage. The time constant is long, in the millisecond range, because of its unique construction. Use of this calorimeter has produced 100% data recovery, and agreement with true deposition to less than 10%.

  3. Dielectric-wall linear accelerator with a high voltage fast rise time switch that includes a pair of electrodes between which are laminated alternating layers of isolated conductors and insulators

    DOEpatents

    Caporaso, G.J.; Sampayan, S.E.; Kirbie, H.C.

    1998-10-13

    A dielectric-wall linear accelerator is improved by a high-voltage, fast rise-time switch that includes a pair of electrodes between which are laminated alternating layers of isolated conductors and insulators. A high voltage is placed between the electrodes sufficient to stress the voltage breakdown of the insulator on command. A light trigger, such as a laser, is focused along at least one line along the edge surface of the laminated alternating layers of isolated conductors and insulators extending between the electrodes. The laser is energized to initiate a surface breakdown by a fluence of photons, thus causing the electrical switch to close very promptly. Such insulators and lasers are incorporated in a dielectric wall linear accelerator with Blumlein modules, and phasing is controlled by adjusting the length of fiber optic cables that carry the laser light to the insulator surface. 12 figs.

  4. Dielectric-wall linear accelerator with a high voltage fast rise time switch that includes a pair of electrodes between which are laminated alternating layers of isolated conductors and insulators

    DOEpatents

    Caporaso, George J.; Sampayan, Stephen E.; Kirbie, Hugh C.

    1998-01-01

    A dielectric-wall linear accelerator is improved by a high-voltage, fast rise-time switch that includes a pair of electrodes between which are laminated alternating layers of isolated conductors and insulators. A high voltage is placed between the electrodes sufficient to stress the voltage breakdown of the insulator on command. A light trigger, such as a laser, is focused along at least one line along the edge surface of the laminated alternating layers of isolated conductors and insulators extending between the electrodes. The laser is energized to initiate a surface breakdown by a fluence of photons, thus causing the electrical switch to close very promptly. Such insulators and lasers are incorporated in a dielectric wall linear accelerator with Blumlein modules, and phasing is controlled by adjusting the length of fiber optic cables that carry the laser light to the insulator surface.

  5. Systematic investigation of effects of exciton–acoustic-phonon scattering on photoluminescence rise times of free excitons in GaAs/Al{sub 0.3}Ga{sub 0.7}As single quantum wells

    SciTech Connect

    Nakayama, Masaaki Ohno, Tatsuya; Furukawa, Yoshiaki

    2015-04-07

    We have systematically investigated the photoluminescence (PL) dynamics of free excitons in GaAs/Al{sub 0.3}Ga{sub 0.7}As single quantum wells, focusing on the energy relaxation process due to exciton–acoustic-phonon scattering under non-resonant and weak excitation conditions as a function of GaAs-layer thickness from 3.6 to 12.0 nm and temperature from 30 to 50 K. The free exciton characteristics were confirmed by observation that the PL decay time has a linear dependence with temperature. We found that the free exciton PL rise rate, which is the reciprocal of the rise time, is inversely linear with the GaAs-layer thickness and linear with temperature. This is consistent with a reported theoretical study of the exciton–acoustic-phonon scattering rate in the energy relaxation process in quantum wells. Consequently, it is conclusively verified that the PL rise rate is dominated by the exciton–acoustic-phonon scattering rate. In addition, from quantitative analysis of the GaAs-layer thickness and temperature dependences, we suggest that the PL rise rate reflects the number of exciton–acoustic-phonon scattering events.

  6. Paleoceanography/climate and taphonomy at intermediate water depth in the Subtropical Western North Pacific Ocean over the last 1 Ma from IODP Exp 350 Sites U1436C and U1437B, Izu arc area.

    NASA Astrophysics Data System (ADS)

    Vautravers, Maryline

    2015-04-01

    IODP Expedition 350 Site U1436C lies in the western part of the Izu fore arc basin, ~60 km east of the arc front volcano Aogashima, at 1776 m water depth. This site is a technical hole (only a 150 m long record) for a potential future deep drilling by Chikyu. Site U1437 is located in the Izu rear arc, ~90 km west of the arc front volcanoes Myojinsho and Myojin Knoll, at 2117 m water depth. At this site in order to study the evolution of the IZU rear arc crust we recovered a 1800 meter long sequence of mud and volcaniclastic sediments. These sites provide a rich and well-preserved record of volcanic eruptions within the area of the Izu Bonin-Arc. However, the material recovered, mostly mud with ash containing generally abundant planktonic foraminifera, can support additional paleoceanographic goals in an area affected by the Kuroshio Current. Also, the hydrographic divide created by the Izu rise provides a rare opportunity to gain some insight into the operation of the global intermediate circulation. The Antarctic Intermediate Water Mass is more influential at the depth of U1437B in the West and the North Pacific Intermediate Water at Site U1436C to the East. We analyzed 460 samples recovered at Sites U1436C and U1437B for a quantitative planktonic foraminifer study, and also for carbonate preservation indices, including: shell weight, percent planktonic foraminifera fragments planktonic foraminifer concentrations, various faunal proxies, and benthic/planktonic ratio. We measured the stable isotopes for a similar number of samples using the thermocline dwelling Neogloboquadrina dutertrei. The dataset presented here covers the last 1 Ma at Site U1437B and 0.9 Ma at Site U1436C. The age models for the two sites are largely established through stable isotope stratigraphy (this study). On their respective age models we evidence based on polar/subpolar versus subtropical faunal assemblages changes qualitative surface water temperature variations recording the changing

  7. Reply to Comment on "Zircon U-Th-Pb dating using LA-ICP-MS: Simultaneous U-Pb and U-Th dating on the 0.1 Ma Toya Tephra, Japan"

    NASA Astrophysics Data System (ADS)

    Ito, Hisatoshi

    2015-04-01

    Guillong et al. (2015) mentioned that corrections for abundance sensitivity for 232Th and molecular zirconium sesquioxide ions (Zr2O3+) are critical for reliable determination of 230Th abundances in zircon for LA-ICP-MS analyses. There is no denying that more rigorous treatments are necessary to obtain more reliable ages than those in Ito (2014). However, as shown in Fig. 2 in Guillong et al. (2015), the uncorrected (230Th)/(238U) for reference zircons except for Mud Tank are only 5-20% higher than unity. Since U abundance of Toya Tephra zircons that have U-Pb ages < 1 Ma is in-between that of FCT and Plesovice, the overestimation of 230Th by both abundance sensitivity and molecular interferences is expected to be 5-20% for the Toya Tephra. Moreover Ito (2014) obtained U-Th ages of the Toya Tephra by comparison with Fish Canyon Tuff (FCT) data. Because both the FCT and the Toya Tephra have similar trends of overestimation of 230Th, the effect of overestimation of 230Th to cause overestimation of U-Th age should be cancelled out or negligible. Therefore the pivotal conclusion in Ito (2014) that simultaneous U-Pb and U-Th dating using LA-ICP-MS is possible and useful for Quaternary zircons holds true.

  8. Analysis of implosion and spectroscopic characteristics of combined planar wire arrays composed from low- and mid-z wire materials on the 1MA pulsed power generator at UNR

    NASA Astrophysics Data System (ADS)

    Safronova, A. S.; Kantsyrev, V. L.; Ouart, N. D.; Yilmaz, M. F.; Williamson, K.; Shlyaptseva, V.; Shrestha, I.; Osborne, G.; Coverdale, C. A.; Deeney, C.

    2007-11-01

    Analysis of single combined planar wire array experiments is presented. In these experiments, which were conducted at the 1 MA pulsed power generator at UNR, the Z-pinch load consisted of two Al and several Cu alloyed wires mounted in a single linear row with a 1 mm gap. Two wires of the primary Cu material were replaced by Al wires with the similar mass at three different locations. Implosion and radiative characteristics of such arrays were studied in connection with the particular location of two Al wires using filtered PCD and XRD detectors, a bare bolometer, time-gated and time-integrated pinhole cameras, and time-integrated, spatially resolved and time-gated spatially-integrated spectrometers. Non-LTE kinetic models were used to provide plasma parameters and to estimate opacity effects. This work was supported by NNSA under DOE Coop. Agr. DE-FC52-06NA27588, DE-FC52-06NA27586, and in part by DE-FC52-06NA27616. Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States department of Energy under Contract DE-AC04-94AL85000.

  9. Design of a 5-MA 100-ns linear-transformer-driver accelerator for wire array Z-pinch experiments

    NASA Astrophysics Data System (ADS)

    Zhou, Lin; Li, Zhenghong; Wang, Zhen; Liang, Chuan; Li, Mingjia; Qi, Jianmin; Chu, Yanyun

    2016-03-01

    The linear-transformer-driver (LTD) is a recently developed pulsed-power technology that shows great promise for a number of applications. These include a Z -pinch-driven fission-fusion-hybrid reactor that is being developed by the Chinese Academy of Engineering Physics. In support of the reactor development effort, we are planning to build an LTD-based accelerator that is optimized for driving wire-array Z -pinch loads. The accelerator comprises six modules in parallel, each of which has eight series 0.8-MA LTD cavities in a voltage-adder configuration. Vacuum transmission lines are used from the interior of the adder to the central vacuum chamber where the load is placed. Thus the traditional stack-flashover problem is eliminated. The machine is 3.2 m tall and 12 m in outer diameter including supports. A prototype cavity was built and tested for more than 6000 shots intermittently at a repetition rate of 0.1 Hz. A novel trigger, in which only one input trigger pulse is needed by utilizing an internal trigger brick, was developed and successfully verified in these shots. A full circuit modeling was conducted for the accelerator. The simulation result shows that a current pulse rising to 5.2 MA in 91 ns (10%-90%) can be delivered to the wire-array load, which is 1.5 cm in height, 1.2 cm in initial radius, and 1 mg in mass. The maximum implosion velocity of the load is 32 cm /μ s when compressed to 0.1 of the initial radius. The maximum kinetic energy is 78 kJ, which is 11.7% of the electric energy stored in the capacitors. This accelerator is supposed to enable a radiation energy efficiency of 20%-30%, providing a high efficient facility for research on the fast Z pinch and technologies for repetition-rate-operated accelerators.

  10. Axial Magnetic Field Compression within Radial Foil Plasma Jets, Experiment and Simulation

    NASA Astrophysics Data System (ADS)

    Byvank, Tom; Potter, William; Chang, Jae Young; Banasek, Jacob; Greenly, John; Seyler, Charles; Kusse, Bruce

    2015-11-01

    Compression of an axial magnetic field correlates with density hollowing and azimuthal rotation of a plasma jet generated by the COBRA pulsed power machine (1 MA peak current in 100 ns rise time) in a radial foil (15 μm Al thin disk) configuration. The plasma jet compresses an external 1 T axial magnetic field (Bz) as it collimates along the central z-axis. Experimental measurements use a Bdot magnetic probe placed in the center of the hollow plasma jet. Experimental results show compression of the 1 T Bz field to 2.4 +/- 0.3 T. Predictions made by the extended magnetohydrodynamics (XMHD) code, PERSEUS, show a 5.0 +/- 0.7 T field at the probe location. We overview physical reasons for the discrepancy between the experimental and simulation magnetic field compression measurements.

  11. Cyclostratigraphy and eccentricity tuning of the early Oligocene through early Miocene (30.1-17.1 Ma): Cibicides mundulus stable oxygen and carbon isotope records from Walvis Ridge Site 1264

    NASA Astrophysics Data System (ADS)

    Liebrand, Diederik; Beddow, Helen M.; Lourens, Lucas J.; Pälike, Heiko; Raffi, Isabella; Bohaty, Steven M.; Hilgen, Frederik J.; Saes, Mischa J. M.; Wilson, Paul A.; van Dijk, Arnold E.; Hodell, David A.; Kroon, Dick; Huck, Claire E.; Batenburg, Sietske J.

    2016-09-01

    Few astronomically calibrated high-resolution (≤5 kyr) climate records exist that span the Oligocene-Miocene time interval. Notably, available proxy records show responses varying in amplitude at frequencies related to astronomical forcing, and the main pacemakers of global change on astronomical time-scales remain debated. Here we present newly generated X-ray fluorescence core scanning and benthic foraminiferal stable oxygen and carbon isotope records from Ocean Drilling Program Site 1264 (Walvis Ridge, southeastern Atlantic Ocean). Complemented by data from nearby Site 1265, the Site 1264 benthic stable isotope records span a continuous ∼13-Myr interval of the Oligo-Miocene (30.1-17.1 Ma) at high resolution (∼3.0 kyr). Spectral analyses in the stratigraphic depth domain indicate that the largest amplitude variability of all proxy records is associated with periods of ∼ 3.4 m and ∼ 0.9 m, which correspond to 405- and ∼110-kyr eccentricity, using a magnetobiostratigraphic age model. Maxima in CaCO3 content, δ18O and δ13C are interpreted to coincide with ∼110 kyr eccentricity minima. The strong expression of these cycles in combination with the weakness of the precession- and obliquity-related signals allow construction of an astronomical age model that is solely based on tuning the CaCO3 content to the nominal (La2011_ecc3L) eccentricity solution. Very long-period eccentricity maxima (∼2.4-Myr) are marked by recurrent episodes of high-amplitude ∼110-kyr δ18O cycles at Walvis Ridge, indicating greater sensitivity of the climate/cryosphere system to short eccentricity modulation of climatic precession. In contrast, the responses of the global (high-latitude) climate system, cryosphere, and carbon cycle to the 405-kyr cycle, as expressed in benthic δ18O and especially δ13C signals, are more pronounced during ∼2.4-Myr minima. The relationship between the recurrent episodes of high-amplitude ∼110-kyr δ18O cycles and the ∼1.2-Myr amplitude

  12. Hydrothermal mineral deposits and fossil biota from a young (0.1 Ma) abyssal hill on the flank of the fast spreading East Pacific Rise: Evidence for pulsed hydrothermal flow and tectonic tapping of axial heat and fluids

    NASA Astrophysics Data System (ADS)

    Benjamin, Sara B.; Haymon, Rachel M.

    2006-05-01

    Heat flow data indicate that most hydrothermal heat loss from ocean lithosphere occurs on the flanks of the mid-ocean ridge, but few ridge flank hydrothermal sites are known. We describe the first nonseamount, abyssal hill hydrothermal mineral deposits to be recovered from the fast spreading East Pacific Rise (EPR) flanks. Deposits were sampled at two sites on an abyssal hill ˜5 km east of the EPR axis, just north of Clipperton Fracture Zone at 10°20'N, on ˜0.1 Ma lithosphere. "Tevnia Site" is on the axis-facing fault scarp of the hill, and "Ochre Site" is located ˜950 m farther east near the base of the outward-facing slope. Clusters of fragile, biodegradable Tevnia worm tubes at both sites indicate that hydrothermal fluids carried sufficient H2S to sustain Tevnia worms, and that fluid flow waned too recently to allow time for tube destruction. Presence of microbial mats and other biota also are consistent with recent waning of flow. The deposits are mineralogically zoned, from nontronite-celadonite to hydrous Fe-oxide+opaline silica to Mn-oxide (birnessite and todorokite). This places them into a distinctive class of Fe-Si-Mn hydrothermal deposits found along tectonic cracks and faults in young oceanic crust, and suggests that (1) deposits precipitated along an O2 gradient between ambient seawater and hydrothermal fluid; (2) fluid temperatures were <150°C and (3) undiluted fluids were Mg-depleted, and Fe-, K-, Si- and Mn-enriched. These fluids may derive from high temperature seawater-basalt interaction ± phase separation proximal to the axial melt zone, and lose Cu and Zn before venting due to conductive cooling and/or pH increase. Ochre Site samples are purely hydrothermal; however, Tevnia Site samples incorporate volcanic, sedimentary, and fossil components, and exhibit at least three generations of fracturing and hydrothermal cementation. The Tevnia Site breccias accumulated on the exposed fault scarp, possibly during multiple slip events and

  13. Ablation dynamics in coiled wire-array Z-pinches

    SciTech Connect

    Hall, G. N.; Lebedev, S. V.; Suzuki-Vidal, F.; Swadling, G.; Chittenden, J. P.; Bland, S. N.; Harvey-Thompson, A.; Knapp, P. F.; Blesener, I. C.; McBride, R. D.; Chalenski, D. A.; Blesener, K. S.; Greenly, J. B.; Pikuz, S. A.; Shelkovenko, T. A.; Hammer, D. A.; Kusse, B. R.

    2013-02-15

    Experiments to study the ablation dynamics of coiled wire arrays were performed on the MAGPIE generator (1 MA, 240 ns) at Imperial College, and on the COBRA generator at Cornell University's Laboratory of Plasma Studies (1 MA, 100 ns). The MAGPIE generator was used to drive coiled wires in an inverse array configuration to study the distribution of ablated plasma. Using interferometry to study the plasma distribution during the ablation phase, absolute quantitative measurements of electron line density demonstrated very high density contrasts between coiled ablation streams and inter-stream regions many millimetres from the wire. The measured density contrasts for a coiled array were many times greater than that observed for a conventional array with straight wires, indicating that a much greater axial modulation of the ablated plasma may be responsible for the unique implosion dynamics of coiled arrays. Experiments on the COBRA generator were used to study the complex redirection of plasma around a coiled wire that gives rise to the ablation structure exhibited by coiled arrays. Observations of this complex 3D plasma structure were used to validate the current model of coiled array ablation dynamics [Hall et al., Phys. Rev. Lett. 100, 065003 (2008)], demonstrating irrefutably that plasma flow from the wires behaves as predicted. Coiled wires were observed to ablate and implode in the same manner on both machines, indicating that current rise time should not be an issue for the scaling of coiled arrays to larger machines with fast current rise times.

  14. High voltage electrical amplifier having a short rise time

    DOEpatents

    Christie, David J.; Dallum, Gregory E.

    1991-01-01

    A circuit, comprising an amplifier and a transformer is disclosed that produces a high power pulse having a fast response time, and that responds to a digital control signal applied through a digital-to-analog converter. The present invention is suitable for driving a component such as an electro-optic modulator with a voltage in the kilovolt range. The circuit is stable at high frequencies and during pulse transients, and its impedance matching circuit matches the load impedance with the output impedance. The preferred embodiment comprises an input stage compatible with high-speed semiconductor components for amplifying the voltage of the input control signal, a buffer for isolating the input stage from the output stage; and a plurality of current amplifiers connected to the buffer. Each current amplifier is connected to a field effect transistor (FET), which switches a high voltage power supply to a transformer which then provides an output terminal for driving a load. The transformer comprises a plurality of transmission lines connected to the FETs and the load. The transformer changes the impedance and voltage of the output. The preferred embodiment also comprises a low voltage power supply for biasing the FETs at or near an operational voltage.

  15. Research on fast rise time EMP radiating-wave simulator

    NASA Astrophysics Data System (ADS)

    Fan, Lisi; Liu, Haitao; Wang, Yun

    2013-03-01

    This paper presents an antenna of High altitude electromagnetic pulse (HEMP) radiating-wave simulator which expands the testing zone larger than the traditional transmission line simulator. The numerical results show that traverse electramagnetic (TEM) antenna can be used to radiate HEMP simulation radiating wave, but in low frequency band the emissive capability is poor. The experiment proves the numerical model is valid. The results of this paper show that TEM antenna can be used to HEMP radiating-wave simulator, and can prove the low frequency radiation capability through resistance loaded method.

  16. Dynamics of high-speed micro-drop impact: numerical simulations and experiments at frame-to-frame times below 100 ns.

    PubMed

    Visser, Claas Willem; Frommhold, Philipp Erhard; Wildeman, Sander; Mettin, Robert; Lohse, Detlef; Sun, Chao

    2015-03-01

    Technologies including (3D-) (bio-)printing, diesel engines, laser-induced forward transfer, and spray cleaning require optimization and therefore understanding of micrometer-sized droplets impacting at velocities beyond 10 m s(-1). However, as yet, this regime has hardly been addressed. Here we present the first time-resolved experimental investigation of microdroplet impact at velocities up to V0 = 50 m s(-1), on hydrophilic and -phobic surfaces at frame rates exceeding 10(7) frames per second. A novel method to determine the 3D-droplet profile at sub-micron resolution at the same frame rates is presented, using the fringe pattern observed from a bottom view. A numerical model, which is validated by the side- and bottom-view measurements, is employed to study the viscous boundary layer inside the droplet and the development of the rim. The spreading dynamics, the maximal spreading diameter, the boundary layer thickness, the rim formation, and the air bubble entrainment are compared to theory and previous experiments. In general, the impact dynamics are equal to millimeter-sized droplet impact for equal Reynolds-, Weber- and Stokes numbers (Re, We, and St, respectively). Using our numerical model, effective scaling laws for the progression of the boundary layer thickness and the rim diameter are provided. The dimensionless boundary layer thickness develops in time (t) according to δBL ~ D0/√Re(t/τ)0.45, and the diameter of the rim develops as DRim ~ D0/√We(t/τ)0.68, with drop diameter D0 and inertial time scale τ = D0/V0. These scalings differ from previously assumed, but never validated, values. Finally, no splash is observed, at variance with many predictions but in agreement with models including the influence of the surrounding gas. This confirms that the ambient gas properties are key ingredients for splash threshold predictions.

  17. Dynamics of high-speed micro-drop impact: numerical simulations and experiments at frame-to-frame times below 100 ns.

    PubMed

    Visser, Claas Willem; Frommhold, Philipp Erhard; Wildeman, Sander; Mettin, Robert; Lohse, Detlef; Sun, Chao

    2015-03-01

    Technologies including (3D-) (bio-)printing, diesel engines, laser-induced forward transfer, and spray cleaning require optimization and therefore understanding of micrometer-sized droplets impacting at velocities beyond 10 m s(-1). However, as yet, this regime has hardly been addressed. Here we present the first time-resolved experimental investigation of microdroplet impact at velocities up to V0 = 50 m s(-1), on hydrophilic and -phobic surfaces at frame rates exceeding 10(7) frames per second. A novel method to determine the 3D-droplet profile at sub-micron resolution at the same frame rates is presented, using the fringe pattern observed from a bottom view. A numerical model, which is validated by the side- and bottom-view measurements, is employed to study the viscous boundary layer inside the droplet and the development of the rim. The spreading dynamics, the maximal spreading diameter, the boundary layer thickness, the rim formation, and the air bubble entrainment are compared to theory and previous experiments. In general, the impact dynamics are equal to millimeter-sized droplet impact for equal Reynolds-, Weber- and Stokes numbers (Re, We, and St, respectively). Using our numerical model, effective scaling laws for the progression of the boundary layer thickness and the rim diameter are provided. The dimensionless boundary layer thickness develops in time (t) according to δBL ~ D0/√Re(t/τ)0.45, and the diameter of the rim develops as DRim ~ D0/√We(t/τ)0.68, with drop diameter D0 and inertial time scale τ = D0/V0. These scalings differ from previously assumed, but never validated, values. Finally, no splash is observed, at variance with many predictions but in agreement with models including the influence of the surrounding gas. This confirms that the ambient gas properties are key ingredients for splash threshold predictions. PMID:25607820

  18. Development of novel techniques to study the magnetic field evolution in wire array Z-pinches and X pinches

    NASA Astrophysics Data System (ADS)

    Syed, Wasif

    Understanding the magnetic field topology in wire-array Z-pinches is of great significance for their ultimate application to stockpile stewardship and inertial confinement fusion. We have developed and tested several novel techniques involving material-based sensors to measure magnetic fields as a function of space and time in high energy density plasmas on pulsed power machines. We first briefly introduce a technique that was used to measure a lower limit of the maximum magnetic field of a sub-microsecond duration pulse using magnetic reversal in CoPt thin films. The time-varying magnetic field was generated by an exploding wire array plasma called an X pinch produced on the 0.5 MA, 100 ns pulse duration, XP pulsed power generator. We then introduce a technique based on Faraday rotation that was used to measure magnetic fields in wire-array Z-pinches produced on the 1 MA, 100 ns rise time, COBRA pulsed power generator as well as on the XP generator. This technique measures magnetic fields as a function of space and time using Faraday rotation of a single longitudinal mode (SLM) laser through a magneto-optically active bulk waveguide, multicomponent terbium borate glass, placed adjacent to, or within, the wire array. We have measured fields > 10 T with 100 ns rise times outside of a wire-array Z-pinch for the entire duration (˜250 ns) of the current pulse and as much as ˜2 T inside a wire-array for ˜40 ns from the start of current. This is the first time that such rapidly varying and large fields have been measured using the terbium borate glass. The third method, also based on Faraday rotation of SLM laser light utilized an integrated optical fiber sensor (a fiber-sensor-fiber assembly) on the XP pulsed power generator that also yielded a measurement of the magnetic field of a wire-array Z-pinch for part of the current pulse. Finally, we repeated the third method by fabricating a "thin film waveguide" of terbium borate glass to increase the spatial resolution

  19. Magnetic Field Measurements in Wire-Array Z-Pinches using Magneto-Optically Active Waveguides

    SciTech Connect

    Syed, Wasif; Blesener, Isaac; Hammer, David A.; Lipson, Michal

    2009-01-21

    Understanding the magnetic field topology in wire-array Z-pinches as a function of time is of great significance to understanding these high-energy density plasmas especially for their ultimate application to stockpile stewardship and inertial confinement fusion. We are developing techniques to measure magnetic fields as a function of space and time using Faraday rotation of a single longitudinal mode (SLM) laser through a magneto-optically active bulk waveguide (multicomponent terbium borate glass) placed adjacent to, or within, the wire array in 1 MA experiments. We have measured fields >10 T with 100 ns rise times outside of a wire-array for the entire duration of the current pulse and as much as {approx}2 T inside a wire-array for {approx}40 ns from the start of current. This is the first time that such rapidly varying and large fields have been measured using these materials. In a dense Z-pinch, these sensing devices may not survive for long but may provide the magnetic field at the position of the sensor that can be used to corroborate magnetic probes, with which we compare our results.

  20. Design and optimization of a gas-puff nozzle for staged Z-pinch experiments using computational fluid dynamics simulations

    NASA Astrophysics Data System (ADS)

    Valenzuela, J. C.; Krasheninnikov, I.; Beg, F. N.; Wessel, F.; Rahman, H.; Ney, P.; Presura, R.; McKee, E.; Darling, T.; Covington, A.

    2015-11-01

    Previous experimental work on staged Z-pinches demonstrated that gas liners can efficiently couple energy and implode uniformly a target-plasma. A 1.5 MA, 1 μs current driver was used to implode a magnetized, Kr liner onto a D + target, producing 1010 neutrons per shot and providing clear evidence of enhanced pinch stability. Time-of-flight data suggest that primary and secondary neutrons were produced. MHD simulations show that in Zebra, a 1.5MA and 100ns rise-time current driver, high fusion gain can be attained when the optimum liner and plasma target conditions are used. In this work we present the design and optimization of a liner-on-target nozzle to be fielded in Zebra and demonstrate high fusion gain at 1 MA current level. The nozzle is composed of an annular high atomic number gas-puff and an on-axis plasma gun that will deliver the ionized deuterium target. The nozzle optimization was carried out using the computational fluid dynamics (CFD) code fluent and the MHD code Mach2. The CFD simulation produces density and temperature profiles, as a function of the nozzle shapes and gas conditions, which are then used in Mach2 to find the optimum plasma liner implosion-pinch conditions. Funded by the US Department of Energy, ARPA-E, Control Number 1184-1527.

  1. Magnetic Field Measurements in Wire-Array Z-Pinches using Magneto-Optically Active Waveguides

    NASA Astrophysics Data System (ADS)

    Syed, Wasif; Blesener, Isaac; Hammer, David A.; Lipson, Michal

    2009-01-01

    Understanding the magnetic field topology in wire-array Z-pinches as a function of time is of great significance to understanding these high-energy density plasmas especially for their ultimate application to stockpile stewardship and inertial confinement fusion. We are developing techniques to measure magnetic fields as a function of space and time using Faraday rotation of a single longitudinal mode (SLM) laser through a magneto-optically active bulk waveguide (multicomponent terbium borate glass) placed adjacent to, or within, the wire array in 1 MA experiments. We have measured fields >10 T with 100 ns rise times outside of a wire-array for the entire duration of the current pulse and as much as ˜2 T inside a wire-array for ˜40 ns from the start of current. This is the first time that such rapidly varying and large fields have been measured using these materials. In a dense Z-pinch, these sensing devices may not survive for long but may provide the magnetic field at the position of the sensor that can be used to corroborate magnetic probes, with which we compare our results.

  2. Simple scaling laws for influenza A rise time, duration, and severity.

    PubMed

    Chang, David B; Young, Carl S

    2007-06-21

    Simple scaling laws are developed for the severity and characteristic time scales of influenza A infection in man. The scaling laws are based on a model of the infection described by six coupled ordinary differential equations that describe the time courses of the numbers of infectious viral particles, activated cytotoxic T-lymphocytes, interferon molecules, infected cells, uninfected cells, and the subset of uninfected cells that are protected by interferon from viral infection. Computer simulations show that the disease can be regarded approximately as a two-stage process. In the first stage, the growth in the number of infected cells is determined primarily by the interferon-enhanced limitation in the available number of target cells. In the second stage, the bulk of the duration of the infection is determined mainly by the destruction of the infected cells by the cytotoxic T-lymphocytes. The severity and characteristic times of the infection are found to depend simply on the logarithm of the initial number of viruses. PMID:17379249

  3. Laser pumping of thyristors for fast high current rise-times

    DOEpatents

    Glidden, Steven C.; Sanders, Howard D.

    2013-06-11

    An optically triggered semiconductor switch includes an anode metallization layer; a cathode metallization layer; a semiconductor between the anode metallization layer and the cathode metallization layer and a photon source. The semiconductor includes at least four layers of alternating doping in the form P-N-P-N, in which an outer layer adjacent to the anode metallization layer forms an anode and an outer layer adjacent the cathode metallization layer forms a cathode and in which the anode metallization layer has a window pattern of optically transparent material exposing the anode layer to light. The photon source emits light having a wavelength, with the light from the photon source being configured to match the window pattern of the anode metallization layer.

  4. Implosion dynamics and radiation characteristics of wire-array Z pinches on the Cornell Beam Research Accelerator

    SciTech Connect

    McBride, R. D.; Shelkovenko, T. A.; Pikuz, S. A.; Hammer, D. A.; Greenly, J. B.; Kusse, B. R.; Douglass, J. D.; Knapp, P. F.; Bell, K. S.; Blesener, I. C.; Chalenski, D. A.

    2009-01-15

    Experimental results are presented that characterize the implosion dynamics and radiation output of wire-array Z pinches on the 1-MA, 100-ns rise-time Cornell Beam Research Accelerator (COBRA) [J. B. Greenly et al., Rev. Sci. Instrum. 79, 073501 (2008)]. The load geometries investigated include 20-mm-tall cylindrical arrays ranging from 4 to 16 mm in diameter, and consisting of 8, 16, or 32 wires of either tungsten, aluminum, or Invar (64% iron, 36% nickel). Diagnostics fielded include an optical streak camera, a time-gated extreme-ultraviolet framing camera, a laser shadowgraph system, time-integrated pinhole cameras, an x-ray wide-band focusing spectrograph with spatial resolution, an x-ray streak camera, a load voltage monitor, a Faraday cup, a bolometer, silicon diodes, and diamond photoconducting detectors. The data produced by the entire suite of diagnostics are analyzed and presented to provide a detailed picture of the overall implosion process and resulting radiation output on COBRA. The highest x-ray peak powers (300-500 GW) and total energy yields (6-10 kJ) were obtained using 4-mm-diameter arrays that stagnated before peak current. Additional findings include a decrease in soft x-ray radiation prior to stagnation as the initial wire spacing was changed from 1.6 mm to 785 {mu}m, and a timing correlation between the onset of energetic electrons, hard x-ray generation, and the arrival of trailing current on axis - a correlation that is likely due to the formation of micropinches. The details of these and other findings are presented and discussed.

  5. Implosion dynamics and radiation characteristics of wire-array Z pinches on the Cornell Beam Research Accelerator

    NASA Astrophysics Data System (ADS)

    McBride, R. D.; Shelkovenko, T. A.; Pikuz, S. A.; Hammer, D. A.; Greenly, J. B.; Kusse, B. R.; Douglass, J. D.; Knapp, P. F.; Bell, K. S.; Blesener, I. C.; Chalenski, D. A.

    2009-01-01

    Experimental results are presented that characterize the implosion dynamics and radiation output of wire-array Z pinches on the 1-MA, 100-ns rise-time Cornell Beam Research Accelerator (COBRA) [J. B. Greenly et al., Rev. Sci. Instrum. 79, 073501 (2008)]. The load geometries investigated include 20-mm-tall cylindrical arrays ranging from 4to16mm in diameter, and consisting of 8, 16, or 32 wires of either tungsten, aluminum, or Invar (64% iron, 36% nickel). Diagnostics fielded include an optical streak camera, a time-gated extreme-ultraviolet framing camera, a laser shadowgraph system, time-integrated pinhole cameras, an x-ray wide-band focusing spectrograph with spatial resolution, an x-ray streak camera, a load voltage monitor, a Faraday cup, a bolometer, silicon diodes, and diamond photoconducting detectors. The data produced by the entire suite of diagnostics are analyzed and presented to provide a detailed picture of the overall implosion process and resulting radiation output on COBRA. The highest x-ray peak powers (300-500GW) and total energy yields (6-10kJ) were obtained using 4-mm-diameter arrays that stagnated before peak current. Additional findings include a decrease in soft x-ray radiation prior to stagnation as the initial wire spacing was changed from 1.6mmto785μm, and a timing correlation between the onset of energetic electrons, hard x-ray generation, and the arrival of trailing current on axis—a correlation that is likely due to the formation of micropinches. The details of these and other findings are presented and discussed.

  6. Dietary changes of large herbivores in the Turkana Basin, Kenya from 4 to 1 Ma

    PubMed Central

    Cerling, Thure E.; Andanje, Samuel A.; Blumenthal, Scott A.; Brown, Francis H.; Chritz, Kendra L.; Harris, John M.; Hart, John A.; Kirera, Francis M.; Kaleme, Prince; Leakey, Louise N.; Leakey, Meave G.; Levin, Naomi E.; Manthi, Fredrick Kyalo; Passey, Benjamin H.; Uno, Kevin T.

    2015-01-01

    A large stable isotope dataset from East and Central Africa from ca. 30 regional collection sites that range from forest to grassland shows that most extant East and Central African large herbivore taxa have diets dominated by C4 grazing or C3 browsing. Comparison with the fossil record shows that faunal assemblages from ca. 4.1–2.35 Ma in the Turkana Basin had a greater diversity of C3–C4 mixed feeding taxa than is presently found in modern East and Central African environments. In contrast, the period from 2.35 to 1.0 Ma had more C4-grazing taxa, especially nonruminant C4-grazing taxa, than are found in modern environments in East and Central Africa. Many nonbovid C4 grazers became extinct in Africa, notably the suid Notochoerus, the hipparion equid Eurygnathohippus, the giraffid Sivatherium, and the elephantid Elephas. Other important nonruminant C4-grazing taxa switched to browsing, including suids in the lineage Kolpochoerus-Hylochoerus and the elephant Loxodonta. Many modern herbivore taxa in Africa have diets that differ significantly from their fossil relatives. Elephants and tragelaphin bovids are two groups often used for paleoecological insight, yet their fossil diets were very different from their modern closest relatives; therefore, their taxonomic presence in a fossil assemblage does not indicate they had a similar ecological function in the past as they do at present. Overall, we find ecological assemblages of C3-browsing, C3–C4-mixed feeding, and C4-grazing taxa in the Turkana Basin fossil record that are different from any modern ecosystem in East or Central Africa. PMID:26240344

  7. Sediment Flux from Stratigraphy: Insights from <1 Ma to >300 Ma Sedimentary Archives

    NASA Astrophysics Data System (ADS)

    Romans, B.; Mason, C. C.; Eriksson, K. A.

    2014-12-01

    Tectonic or climate signals that originate in net-erosional catchments are transmitted down-system as sediment. The accumulation of that sediment in net-depositional regions and preservation as stratigraphy can be accessed and used to reconstruct signal generation and propagation. Studies of modern to <20 ka sedimentary systems suggest that signal propagation (or lack thereof) is, in part, controlled by the size, relief, and other morphologic characteristics of sediment-production segments. Thus, it's critical to measure, estimate, or infer aspects of the feeder catchment when reconstructing system behavior from sedimentary deposits. Here, we present results from two studies aimed at determining paleo-sediment flux from stratigraphic archives. The first study uses outcropping middle Pleistocene (~0.6 Ma) alluvial-fan deposits in the Panamint Mountains, California, to investigate the relationship of sediment supply to stratigraphic architecture in a small catchment-fan system. The youth of this system allows us to estimate fan volumes from facies architecture and depositional system dimensions based on catchment-area to fan-area relationships of nearby modern systems. These data, combined with preliminary cosmogenic radionuclide-derived paleo-denudation rates, provide an opportunity to examine the nature of erosional signal propagation. The second study examines much older, Upper Mississippian (~325 Ma), fluvial and deltaic strata. Absolute chronologic tools to calculate centennial-millennial rates in deep-time sedimentary archives do not yet exist. Here, we use the extraordinary tidal rhythmite deposits of the Pride Shale in the Appalachian Basin as a high-resolution chronometer to constrain the duration of basin filling. We then use the scale of fluvial channel bodies in the underlying and overlying units combined with climate-specific empirical relationships derived from modern systems to estimate the size of the paleo-catchment. The resultant estimates of sediment yield allow calculation of denudation rates for a system in which the catchment has long-since eroded.

  8. Opening switches for a 5 MJ, 1 MA energy storage transformer

    NASA Astrophysics Data System (ADS)

    Clements, Neal D.; Johnson, Donald E.

    1991-01-01

    Two possible switch topologies used to switch the primary of an energy storage transformer are compared. A series-connected semiconductor/vacuum interrupter switch and an all-solid-state switch are sized for a 5-MJ energy storage transformer. Gate-turn-off (GTO) thyristors are used as the semiconductor switches. Total mass estimates, operating characteristics, and applicability to a space-based pulsed power system are discussed. Both designs store the commutation energy in capacitors. The commutation energy is then dissipated in resistors after switching has occurred. The capacitor mass is shown to dominate the total switch mass. Therefore, the mass of both switches is approximately equal. The advantages of the all-solid-state switch include high reliability, no moving parts, proven design, and a high probability of future mass reduction with new semiconductor device developments. The all-solid-state switch has a higher On-state power dissipation than the vacuum interrupter switch. It is suggested that the advantages of the all-solid-state switch outweigh the disadvantages of the higher power dissipation.

  9. Systematic tapping of independent magma chambers during the 1 Ma Kidnappers supereruption

    NASA Astrophysics Data System (ADS)

    Cooper, George F.; Wilson, Colin J. N.; Millet, Marc-Alban; Baker, Joel A.; Smith, Euan G. C.

    2012-01-01

    The 1.0 Ma Kidnappers supereruption (~ 1200 km 3 DRE) from Mangakino volcanic centre, Taupo Volcanic Zone, New Zealand, produced a large phreatomagmatic fall deposit followed by an exceptionally widespread ignimbrite. Detailed sampling and analysis of glass shards and mineral phases have been undertaken through a proximal 4.0 m section of the fall deposit, representing the first two-thirds of erupted extra-caldera material. Major and trace element chemistries of glass shards define three distinct populations (types A, B and C), which systematically change in proportion through the fall deposit and are inferred to represent three magma types. Type B glass and biotite first appear at the same level (~ 0.95 m above base) in the fall deposit suggesting later tapping of a biotite-bearing magma. Plagioclase and Fe-Ti oxide compositions show bimodal distributions, which are linked to types A and B glass compositions. Temperature and pressure (T-P) estimates from hornblende and Fe-Ti oxide equilibria from each magma type are similar and therefore the three magma bodies were adjacent, not vertically stacked, in the crust. Most hornblende model T-P estimates range from 770 to 840 °C and 90 to 170 MPa corresponding to storage depths of ~ 4.0-6.5 km. Hornblende model T-P estimates coupled with in situ trace element fingerprinting imply that the magma bodies were individually well mixed, and not stratified. Compositional gaps between the three glass compositional types imply that no mixing between these magmas occurred. We interpret these data, coupled with the systematic changes in shard compositional proportions through the fall deposit, to reflect that three independent melt-dominant bodies of magma contributed large (A, ~ 270 km 3), medium (B, ~ 90 km 3) and small (C, ~ 40 km 3) volumes (as reflected in the fall deposits) and were systematically tapped during the eruption. We propose that the systematic evacuation of the three independent magma bodies implies that there was tectonic triggering and linkage of eruptions. Our results show that supereruptions can be generated by near simultaneous multiple eruptions from independent magma chambers rather than the evacuation of a large single unitary magma chamber.

  10. Studies of Hot Spots in Imploding Wire Arrays at 1 MA on COBRA

    SciTech Connect

    Pikuz, Sergey A.; Shelkovenko, Tatiana A.; McBride, Ryan D.; Hammer, David A.

    2009-01-21

    We present recent results from hot spot investigations in imploding Al wire array z-pinches on the COBRA generator at Cornell University using x-ray diagnostics. Measurements of the temporal and spatial distribution of hot spots in stagnating plasmas by an x-ray streak-camera are included. Experiments show that hot spots have nanosecond lifetime and appear randomly along the array axis after plasma stagnation in secondary pinches in 8 mm diameter and during plasma stagnation in the arrays with 4 mm diameter.

  11. Early time studies of cylindrical liner implosions at 1 MA on COBRA

    SciTech Connect

    Atoyan, L. Byvank, T. Cahill, A. D. Hoyt, C. L. Grouchy, P. W. L. de Potter, W. M. Kusse, B. R. Hammer, D. A.

    2014-12-15

    Tests of the magnetized liner inertial fusion (MagLIF) concept will make use of the 27 MA Z machine at Sandia National Laboratories, Albuquerque, to implode a cylindrical metal liner to compress and heat preheated, magnetized plasma contained within it. While most pulsed power machines produce much lower currents than the Z-machine, there are issues that can still be addressed on smaller scale facilities. Recent work on the Cornell Beam Research Accelerator (COBRA) has made use of 10 mm long and 4 mm diameter metal liners having different wall thicknesses to study the initiation of plasma on the liner’s surface as well as axial magnetic field compression [P.-A. Gourdain et al., Nucl. Fusion 53, 083006 (2013)]. This report presents experimental results with non-imploding liners, investigating the impact the liner’s surface structure has on initiation and ablation. Extreme ultraviolet (XUV) imaging and optical 12 frame camera imaging were used to observe and assess emission non-uniformities as they developed. Axial and side-on interferometry was used to determine the distribution of plasma near the liner surface, including the impact of non-uniformities during the plasma initiation and ablation phases of the experiments.

  12. Dietary changes of large herbivores in the Turkana Basin, Kenya from 4 to 1 Ma

    NASA Astrophysics Data System (ADS)

    Cerling, Thure E.; Andanje, Samuel A.; Blumenthal, Scott A.; Brown, Francis H.; Chritz, Kendra L.; Harris, John M.; Hart, John A.; Kirera, Francis M.; Kaleme, Prince; Leakey, Louise N.; Leakey, Meave G.; Levin, Naomi E.; Kyalo Manthi, Fredrick; Passey, Benjamin H.; Uno, Kevin T.

    2015-09-01

    A large stable isotope dataset from East and Central Africa from ca. 30 regional collection sites that range from forest to grassland shows that most extant East and Central African large herbivore taxa have diets dominated by C4 grazing or C3 browsing. Comparison with the fossil record shows that faunal assemblages from ca. 4.1-2.35 Ma in the Turkana Basin had a greater diversity of C3-C4 mixed feeding taxa than is presently found in modern East and Central African environments. In contrast, the period from 2.35 to 1.0 Ma had more C4-grazing taxa, especially nonruminant C4-grazing taxa, than are found in modern environments in East and Central Africa. Many nonbovid C4 grazers became extinct in Africa, notably the suid Notochoerus, the hipparion equid Eurygnathohippus, the giraffid Sivatherium, and the elephantid Elephas. Other important nonruminant C4-grazing taxa switched to browsing, including suids in the lineage Kolpochoerus-Hylochoerus and the elephant Loxodonta. Many modern herbivore taxa in Africa have diets that differ significantly from their fossil relatives. Elephants and tragelaphin bovids are two groups often used for paleoecological insight, yet their fossil diets were very different from their modern closest relatives; therefore, their taxonomic presence in a fossil assemblage does not indicate they had a similar ecological function in the past as they do at present. Overall, we find ecological assemblages of C3-browsing, C3-C4-mixed feeding, and C4-grazing taxa in the Turkana Basin fossil record that are different from any modern ecosystem in East or Central Africa.

  13. Dietary changes of large herbivores in the Turkana Basin, Kenya from 4 to 1 Ma.

    PubMed

    Cerling, Thure E; Andanje, Samuel A; Blumenthal, Scott A; Brown, Francis H; Chritz, Kendra L; Harris, John M; Hart, John A; Kirera, Francis M; Kaleme, Prince; Leakey, Louise N; Leakey, Meave G; Levin, Naomi E; Manthi, Fredrick Kyalo; Passey, Benjamin H; Uno, Kevin T

    2015-09-15

    A large stable isotope dataset from East and Central Africa from ca. 30 regional collection sites that range from forest to grassland shows that most extant East and Central African large herbivore taxa have diets dominated by C4 grazing or C3 browsing. Comparison with the fossil record shows that faunal assemblages from ca. 4.1-2.35 Ma in the Turkana Basin had a greater diversity of C3-C4 mixed feeding taxa than is presently found in modern East and Central African environments. In contrast, the period from 2.35 to 1.0 Ma had more C4-grazing taxa, especially nonruminant C4-grazing taxa, than are found in modern environments in East and Central Africa. Many nonbovid C4 grazers became extinct in Africa, notably the suid Notochoerus, the hipparion equid Eurygnathohippus, the giraffid Sivatherium, and the elephantid Elephas. Other important nonruminant C4-grazing taxa switched to browsing, including suids in the lineage Kolpochoerus-Hylochoerus and the elephant Loxodonta. Many modern herbivore taxa in Africa have diets that differ significantly from their fossil relatives. Elephants and tragelaphin bovids are two groups often used for paleoecological insight, yet their fossil diets were very different from their modern closest relatives; therefore, their taxonomic presence in a fossil assemblage does not indicate they had a similar ecological function in the past as they do at present. Overall, we find ecological assemblages of C3-browsing, C3-C4-mixed feeding, and C4-grazing taxa in the Turkana Basin fossil record that are different from any modern ecosystem in East or Central Africa. PMID:26240344

  14. Double shell liner implosions

    SciTech Connect

    Sorokin, S. A.; Chaikovsky, S. A.

    1997-05-05

    Experiments on the double shell liner (DSL) implosions with and without an initial axial magnetic were performed on the SNOP-3 pulse generator (1.1 MA, 100 ns). In implosions of a DSL without an initial axial magnetic field, high radial compressions of the inner shell were observed, as in previous experiments with an initial axial magnetic field. Possible mechanisms for the formation of the initial azimuthal magnetic field are discussed.

  15. Combined flux compression and plasma opening switch on the Saturn pulsed power generator.

    PubMed

    Felber, Franklin S; Waisman, Eduardo M; Mazarakis, Michael G

    2010-05-01

    A wire-array flux-compression cartridge installed on Sandia's Saturn pulsed power generator doubled the current into a 3-nH load to 6 MA and halved its rise time to 100 ns. The current into the load, however, was unexpectedly delayed by almost 1 micros. Estimates of a plasma flow switch acting as a long-conduction-time opening switch are consistent with key features of the power compression. The results suggest that microsecond-conduction-time plasma flow switches can be combined with flux compression both to amplify currents and to sharpen pulse rise times in pulsed power drivers.

  16. Combined Flux Compression and Plasma Opening Switch on the Saturn Pulsed Power Generator

    SciTech Connect

    Felber, Franklin S.; Waisman, Eduardo M.; Mazarakis, Michael G.

    2010-05-07

    A wire-array flux-compression cartridge installed on Sandia's Saturn pulsed power generator doubled the current into a 3-nH load to 6 MA and halved its rise time to 100 ns. The current into the load, however, was unexpectedly delayed by almost 1 {mu}s. Estimates of a plasma flow switch acting as a long-conduction-time opening switch are consistent with key features of the power compression. The results suggest that microsecond-conduction-time plasma flow switches can be combined with flux compression both to amplify currents and to sharpen pulse rise times in pulsed power drivers.

  17. Distinct Effect of Impact Rise Times on Immediate and Early Neuropathology After Brain Injury in Juvenile Rats

    PubMed Central

    Jayakumar, Archana; Pfister, Bryan J.; Santhakumar, Vijayalakshmi

    2015-01-01

    Traumatic brain injury (TBI) can occur from physical trauma from a wide spectrum of insults ranging from explosions to falls. The biomechanics of the trauma can vary in key features, including the rate and magnitude of the insult. Although the effect of peak injury pressure on neurological outcome has been examined in the fluid percussion injury (FPI) model, it is unknown whether differences in rate of rise of the injury waveform modify cellular and physiological changes after TBI. Using a programmable FPI device, we examined juvenile rats subjected to a constant peak pressure at two rates of injury: a standard FPI rate of rise and a faster rate of rise to the same peak pressure. Immediate postinjury assessment identified fewer seizures and relatively brief loss of consciousness after fast-rise injuries than after standard-rise injuries at similar peak pressures. Compared with rats injured at standard rise, fewer silver-stained injured neuronal profiles and degenerating hilar neurons were observed 4-6 hr after fast-rise FPI. However, 1 week postinjury, both fast- and standard-rise FPI resulted in hilar cell loss and enhanced perforant path-evoked granule cell field excitability compared with sham controls. Notably, the extent of neuronal loss and increase in dentate excitability were not different between rats injured at fast and standard rates of rise to peak pressure. Our data indicate that reduced cellular damage and improved immediate neurological outcome after fast rising primary concussive injuries mask the severity of the subsequent cellular and neurophysiological pathology and may be unreliable as a predictor of prognosis. PMID:24799156

  18. Nested X Pinches on the COBRA Generator

    SciTech Connect

    Shelkovenko, T. A.; Pikuz, S. A.; McBride, R. D.; Knapp, P. F.; Wilhelm, H.; Hammer, D. A.; Sinars, D. B.

    2009-01-21

    Recent results of X pinch studies on the COBRA generator at Cornell University (peak current up to 1.2 MA and rise time of 100 ns) are presented. Using an initial configuration of wires before their twisting, similar to nested cylindrical wire arrays enables the assembly of a symmetric configuration at the X pinch crossing region. It also enables an investigation of multilayered X pinches. X pinches with different configurations, including with different materials in the inner and outer wire layers, were tested.

  19. The influence of laser-induced nanosecond rise-time stress waves on the microstructure and surface chemical activity of single crystal Cu nanopillars

    PubMed Central

    Youssef, G.; Crum, R.; Prikhodko, S. V.; Seif, D.; Po, G.; Ghoniem, N.; Kodambaka, S.; Gupta, V.

    2013-01-01

    An apparatus and test procedure for fabrication and loading of single crystal metal nanopillars under extremely high pressures (>1 GPa) and strain rates (>107 s−1), using laser-generated stress waves, are presented. Single-crystalline Cu pillars (∼1.20 μm in tall and ∼0.45 μm in diameter) prepared via focused ion beam milling of Cu(001) substrates are shock-loaded using this approach with the dilatational stress waves propagating along the [001] axis of the pillars. Transmission electron microscopy observations of shock-loaded pillars show that dislocation density decreases and that their orientation changes with increasing stress wave amplitude, indicative of dislocation motion. The shock-loaded pillars exhibit enhanced chemical reactivity when submerged in oil and isopropyl alcohol solutions, due likely to the exposure of clean surfaces via surface spallation and formation of surface steps and nanoscale facets through dislocation motion to the surface of the pillars, resulting in growth of thin oxide films on the surfaces of the pillars. PMID:23526837

  20. Volume-surface barrier discharge in dried air in three-electrode system fed by impulse high voltage with nanosecond rise time

    NASA Astrophysics Data System (ADS)

    Malashin, Maxim; Rebrov, Igor; Nebogatkin, Sergey; Sokolova, Marina; Nikitin, Alexey; Voevodin, Vadim; Krivov, Sergey

    2016-08-01

    Results of experimental investigation of a volume-surface barrier discharge in a three-electrode system under periodic impulse voltage applied to the surface discharge (SD) electrodes and a d.c. potential applied to an additional third electrode are presented. It is shown that there is a strong influence of polarity and amplitude of the d.c. potential on the direct current "extracted" out of the surface discharge plasma layer by electric field of the third electrode. The amount of charged positive species that constitute the "extracted" current prevails under positive impulse voltage for low values of the negative d.c. potential of the third electrode. The amount of negative species prevails with higher values of the positive d.c. positive of the third electrode. Contribution to the topical issue "6th Central European Symposium on Plasma Chemistry (CESPC-6)", edited by Nicolas Gherardi, Ester Marotta and Cristina Paradisi

  1. The influence of laser-induced nanosecond rise-time stress waves on the microstructure and surface chemical activity of single crystal Cu nanopillars

    SciTech Connect

    Youssef, G.; Crum, R.; Seif, D.; Po, G.; Prikhodko, S. V.; Kodambaka, S.; Ghoniem, N.; Gupta, V.

    2013-02-28

    An apparatus and test procedure for fabrication and loading of single crystal metal nanopillars under extremely high pressures (>1 GPa) and strain rates (>10{sup 7} s{sup -1}), using laser-generated stress waves, are presented. Single-crystalline Cu pillars ({approx}1.20 {mu}m in tall and {approx}0.45 {mu}m in diameter) prepared via focused ion beam milling of Cu(001) substrates are shock-loaded using this approach with the dilatational stress waves propagating along the [001] axis of the pillars. Transmission electron microscopy observations of shock-loaded pillars show that dislocation density decreases and that their orientation changes with increasing stress wave amplitude, indicative of dislocation motion. The shock-loaded pillars exhibit enhanced chemical reactivity when submerged in oil and isopropyl alcohol solutions, due likely to the exposure of clean surfaces via surface spallation and formation of surface steps and nanoscale facets through dislocation motion to the surface of the pillars, resulting in growth of thin oxide films on the surfaces of the pillars.

  2. Acceleration of thin flyer foils with a 1 MA pulsed power device for shock-wave experiments in clumpy foam targets

    NASA Astrophysics Data System (ADS)

    Neff, Stephan; Ford, Jessica; Martinez, David; Plechaty, Christopher; Wright, Sandra; Presura, Radu

    2007-11-01

    The dynamics of shock waves in clumpy media are important for understanding many astrophysical processes, including the triggering of star formation in interstellar gas clouds by passing shock waves. This phenomena can be studied in the laboratory by launching a flyer plate into a low density foam with clumps. Low density foams offer the advantage of relative low sound speeds (a few hundred meters per second) compared to normal solids, thus reducing the flyer speed required to create shock waves. In first experiments aluminum foils with thicknesses between 20 micrometer and 130 micrometer were accelerated to speeds up to 2.3 km/s. In addition, the impact of the flyers on plexiglas targets was studied. Additional measurements will focus on optimizing the flyer properties (thicker flyers, higher velocities) and on characterizing the flyer in more detail (temperature of the flyer and plasma ablation from the flyer). The results of these measurements will be used to design an experiment studying the dynamics of shock waves in clumpy foams, using the 100 TW laser system Leopard for back-lighting the foam target.

  3. Magneto-optical characterizations of FeTe₀̣₅Se₀̣₅ thin films with critical current density over 1 MA/cm²

    DOE PAGES

    Sun, Yue; Li, Qiang; Tsuchiya, Yuji; Pyon, Sunseng; Tamegai, Tsuyoshi; Zhang, Cheng; Ozaki, Toshinori

    2014-12-03

    We performed magneto-optical (MO) measurements on FeTe₀̣₅Se₀̣₅ thin films grown on LaAlO₃ (LAO) and Yttria-stabilized zirconia (YSZ) single-crystalline substrates. These thin films show superconducting transition temperature Tc ~19 K, 4 K higher than the bulk sample. Typical roof-top patterns can be observed in the MO images of thin films grown on LAO and YSZ, from which a large and homogeneous critical current density Jc ~ 3 - 4 x 10⁶ A/cm² at 5 K was obtained. In this study, magnetic flux penetration measurement reveals that the current is almost isotropically distributed in the two thin films. Compared with bulk crystals,more » FeTe₀̣₅Se₀̣₅ thin film demonstrates not only higher Tc, but also much larger Jc, which is attractive for applications.« less

  4. Analysis of x-ray bright spots from triple and single combined Cu and Al planar wire arrays on the 1MA pulsed power generator at UNR

    NASA Astrophysics Data System (ADS)

    Safronova, A. S.; Kantsyrev, V. L.; Esaulov, A. A.; Ouart, N. D.; Yilmaz, M. F.; Weller, M. E.; Williamson, K. M.; Shlyaptseva, V.; Shrestha, I.; Osborne, G. C.; Coverdale, C. A.; Deeney, C.

    2008-11-01

    The recently discovered implosion features of double planar wire arrays, such as the two step precursor formation with the independent implosion of wire arrays made from different materials and bright spot generation in a central precursor column early in time [Kantsyrev et al, PoP 15, 030704 (2008)], led to new experiments with combined triple planar wire arrays (TPWA). Combined TPWA include three planar wire rows that are parallel to each other and made of either Cu or Al alloyed wires. New x-ray data for two configurations (Al/Cu/Al and Cu/Al/Cu) are considered and compared with each other, with the results from combined single planar wire arrays of the same materials, and with Cu uniform cylindrical wire arrays. Emphasis is made on the study of bright spot formation, which is a signature of implosions of planar wire arrays and can be significant for other wire array configurations as well. Work was supported by NNSA/DOE under Coop. Agr. DE-FC52-06NA27588, DE-FC52-06NA27586, and in part by DE-FC52-06NA27616. Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the US DOE under Contract DE-AC04-94AL85000.

  5. Magneto-optical characterizations of FeTe₀̣₅Se₀̣₅ thin films with critical current density over 1 MA/cm²

    SciTech Connect

    Sun, Yue; Li, Qiang; Tsuchiya, Yuji; Pyon, Sunseng; Tamegai, Tsuyoshi; Zhang, Cheng; Ozaki, Toshinori

    2014-12-03

    We performed magneto-optical (MO) measurements on FeTe₀̣₅Se₀̣₅ thin films grown on LaAlO₃ (LAO) and Yttria-stabilized zirconia (YSZ) single-crystalline substrates. These thin films show superconducting transition temperature Tc ~19 K, 4 K higher than the bulk sample. Typical roof-top patterns can be observed in the MO images of thin films grown on LAO and YSZ, from which a large and homogeneous critical current density Jc ~ 3 - 4 x 10⁶ A/cm² at 5 K was obtained. In this study, magnetic flux penetration measurement reveals that the current is almost isotropically distributed in the two thin films. Compared with bulk crystals, FeTe₀̣₅Se₀̣₅ thin film demonstrates not only higher Tc, but also much larger Jc, which is attractive for applications.

  6. Deep Ocean Circulation and Nutrient Contents from Atlantic-Pacific Gradients of Neodymium and Carbon Isotopes During the Last 1 Ma

    NASA Astrophysics Data System (ADS)

    Piotrowski, A. M.; Elderfield, H.; Howe, J. N. W.

    2014-12-01

    The last few million years saw changing boundary conditions to the Earth system which set the stage for bi-polar glaciation and Milankovich-forced glacial-interglacial cycles which dominate Quaternary climate variability. Recent studies have highlighted the relative importance of temperature, ice volume and ocean circulation changes during the Mid-Pleistocene Transition at ~900 ka (Elderfield et al., 2012, Pena and Goldstein, 2014). Reconstructing the history of global deep water mass propagation and its carbon content is important for fully understanding the ocean's role in amplifying Milankovich changes to cause glacial-interglacial transitions. A new foraminiferal-coating Nd isotope record from ODP Site 1123 on the deep Chatham Rise is interpreted as showing glacial-interglacial changes in the bottom water propagation of Atlantic-sourced waters into the Pacific via the Southern Ocean during the last 1 million years. This is compared to globally-distributed bottom water Nd isotope records; including a new deep western equatorial Atlantic Ocean record from ODP Site 929, as well as published records from ODP 1088 and Site 1090 in the South Atlantic (Pena and Goldstein, 2014), and ODP 758 in the deep Indian Ocean (Gourlan et al., 2010). Atlantic-to-Pacific gradients in deep ocean neodymium isotopes are constructed for key time intervals to elucidate changes in deep water sourcing and circulation pathways through the global ocean. Benthic carbon isotopes are used to estimate deep water nutrient contents of deep water masses and constrain locations and modes of deep water formation. References: Elderfield et al. Science 337, 704 (2012) Pena and Goldstein, Science 345, 318 (2014) Gourlan et al., Quaternary Science Reviews 29, 2484-2498 (2010)

  7. Bremsstrahlung target optimization for reflex triodes

    SciTech Connect

    Swanekamp, S. B.; Weber, B. V.; Stephanakis, S. J.; Mosher, D.; Commisso, R. J.

    2008-08-15

    The anode (tantalum) foil thickness in a reflex triode was varied from 2.5 to 250 {mu}m to maximize the dose from bremsstrahlung produced by a 1 MV, 1 MA, 100 ns electron beam. Experiments and computer simulations show that the dose is maximized for a foil thickness of about 25 {mu}m, 1/18th of the electron range computed from the continuous slowing down approximation. For foils thicker than optimum, self-absorption in the foil attenuates 10-100 keV photons, reducing the dose. For foils thinner than optimum, the dose decreases as a result of electron migration to large radius. A simple formula that predicts the optimum thickness as a function of the beam current and voltage is derived that should be applicable to a large range of experimental parameters.

  8. Simulations of electrothermal instability growth in solid aluminum rods

    SciTech Connect

    Peterson, Kyle J.; Yu, Edmund P.; Sinars, Daniel B.; Cuneo, Michael E.; Slutz, Stephen A.; Nakhleh, Charles; Herrmann, Mark C.; Koning, Joseph M.; Marinak, Michael M.

    2013-05-15

    A recent publication [K. J. Peterson et al., Phys. Plasmas 19, 092701 (2012)] describes simulations and experiments of electrothermal instability growth on well characterized initially solid aluminum and copper rods driven with a 20 MA, 100 ns rise time current pulse on Sandia National Laboratories Z accelerator. Quantitative analysis of the high precision radiography data obtained in the experiments showed excellent agreement with simulations and demonstrated levels of instability growth in dense matter that could not be explained by magneto-Rayleigh-Taylor instabilities alone. This paper extends the previous one by examining the nature of the instability growth in 2D simulations in much greater detail. The initial instability growth in the simulations is shown via several considerations to be predominantly electrothermal in nature and provides a seed for subsequent magneto-Rayleigh-Taylor growth.

  9. High-voltage, low-inductance gas switch

    DOEpatents

    Gruner, Frederick R.; Stygar, William A.

    2016-03-22

    A low-inductance, air-insulated gas switch uses a de-enhanced annular trigger ring disposed between two opposing high voltage electrodes. The switch is DC chargeable to 200 kilovolts or more, triggerable, has low jitter (5 ns or less), has pre-fire and no-fire rates of no more than one in 10,000 shots, and has a lifetime of greater than 100,000 shots. Importantly, the switch also has a low inductance (less than 60 nH) and the ability to conduct currents with less than 100 ns rise times. The switch can be used with linear transformer drives or other pulsed-power systems.

  10. Monochromatic x-ray imaging experiments on the Sandia National Laboratories Z facility (invited)

    NASA Astrophysics Data System (ADS)

    Sinars, D. B.; Bennett, G. R.; Wenger, D. F.; Cuneo, M. E.; Hanson, D. L.; Porter, J. L.; Adams, R. G.; Rambo, P. K.; Rovang, D. C.; Smith, I. C.

    2004-10-01

    The Z facility is a 20 MA, 100 ns rise time, pulsed power driver for z-pinch plasma radiation sources. The Z facility can make >200 TW, 1-2 MJ, near-blackbody radiation sources through the compression of cylindrical wire arrays. These sources are being used as drivers to study inertial-confinement fusion capsule implosions, complex radiation-hydrodynamic jet experiments, and wire-array z-pinch physics tests. To backlight plasmas in this environment we have built diagnostics based on spherically bent crystals that provide high spatial resolution (9-10 μm), a narrow spectral bandpass (<0.5 eV), and a large field of view (4 mm×20 mm). These diagnostics use the 2 TW, multi-kJ Z-Beamlet laser to produce x-ray emission sources at 1.865 or 6.151 keV for backlighting.

  11. Modifying Wire Array Z-pinch Ablation Structure and Implosion Dynamics Using Coiled Arrays

    SciTech Connect

    Hall, Gareth N.; Bland, Simon N.; Lebedev, Sergey V.; Chittenden, Jeremy P.; Palmer, James B. A.; Suzuki-Vidal, Francisco A.; Swadling, George F.; Niasse, Nicolas; Knapp, P. F.; Blesener, I. C.; McBride, R. D.; Chalenski, D. A.; Bell, K. S.; Greenly, J. B.; Blanchard, T.; Wilhelm, H.; Hammer, D. A.; Kusse, B. R.; Bott, Simon C.

    2009-01-21

    Coiled arrays, a cylindrical array in which each wire is formed into a helix, suppress the modulation of ablation at the fundamental wavelength. Outside the vicinity of the wire cores, ablation flow from coiled arrays is modulated at the coil wavelength and has a 2-stream structure in the r,{theta} plane. Within the vicinity of the helical wires, ablation is concentrated at positions with the greatest azimuthal displacement and plasma is axially transported from these positions such that the streams become aligned with sections of the coil furthest from the array axis. The GORGON MHD code accurately reproduces this observed ablation structure, which can be understood in terms of JxB forces that result from the interaction of the global magnetic field with a helical current path as well as additional current paths suggested by the simulations. With this ability to control where ablation streamers occur, large wavelength coils were constructed such that the breaks that form in the wires had sufficient axial separation to prevent perturbations in the implosion sheath from merging. This produces a new mode of implosion in which the global instability can be controlled and perturbations correlated between all wires in an array. For large wavelength 8-wire coiled arrays, this produced a dramatic increase in x-ray power, equalling that of a 32-wire straight array. These experiments were carried out on the MAGPIE generator (1 MA, 240 ns) at Imperial College, and the COBRA generator (1 MA, 100 ns) at Cornell University.

  12. High-voltage pulsed generators for electro-discharge technologies

    NASA Astrophysics Data System (ADS)

    Kovalchuk, B. M.; Kharlov, A. V.; Kumpyak, E. V.; Sinebrykhov, V. A.

    2013-09-01

    A high-voltage pulse technology is one of effective techniques for the disintegration and milling of rocks, separation of ores and synthesized materials, recycling of building and elastoplastic materials. We present here the design and test results of two portable HV pulsed generators, designed for materials fragmentation, though some other technological applications are possible as well. Generator #1 consists of low voltage block, high voltage transformer, high voltage capacitive storage block, two electrode gas switch, fragmentation chamber and control system block. Technical characteristics of the #1 generator: stored energy in HV capacitors can be varied from 50 to 1000 J, output voltage up to 300 kV, voltage rise time ~ 50 ns, typical operation regime 1000 pulses bursts with a repetitive rate up to 10 Hz. Generator #2 is made on an eight stages Marx scheme with two capacitors (100 kV-400 nF) per stage, connected in parallel. Two electrode spark gap switches, operated in atmospheric air, are used in the Marx generator. Parameters of the generator: stored energy in capacitors 2÷8 kJ, amplitude of the output voltage 200÷400 kV, voltage rise time on a load 50÷100 ns, repetitive rate up to 0.5 Hz. The fragmentation process can be controlled within a wide range of parameters for both generators.

  13. New Planar Wire Array Experiments on the LTD Generator at U Michigan

    NASA Astrophysics Data System (ADS)

    Weller, M. E.; Safronova, A. S.; Kantsyrev, V. L.; Shrestha, I.; Shlyaptseva, V. V.; Cooper, M. C.; Lorance, M. Y.; Stafford, A.; Petkov, E. E.; Jordan, N. M.; Patel, S. G.; Steiner, A. M.; Yager-Elorriaga, D. A.; Gilgenbach, R. M.

    2014-10-01

    Experiments on planar wire array z-pinches have been carried out on the MAIZE Linear Transformer Driver (LTD) generator at the University of Michigan (UM) for the first time. Specifically, Al (Al 5056, 95% Al, 5% Mg) double planar wire arrays (DPWAs) comprising six wires in each plane with interplanar gaps of 3.0 mm and 6.0 mm and interwire gaps of 0.7 mm and 1.0 mm were imploded with x-ray time-integrated spectra indicating electron temperatures of over 450 eV for K-shell Al and Mg, while producing mostly optically thin lines. In addition to x-ray time-integrated spectra, the diagnostics included x-ray time-integrated pinhole cameras, two silicon diodes, and shadowgraphy, which are analyzed and compared. The MAIZE LTD is capable of supplying up 1.0 MA, 100 kV pulses with 100 ns rise time into a matched load. However, for these experiments the LTD was charged to +-70 kV resulting in up to 0.5 MA with a current rise time of approximately 150 ns. Future experiments and the importance of studying planar wire arrays on LTD devices are discussed. This work supported by NNSA under DOE Cooperative Agreement DE-NA0001984. S. Patel & A. Steiner supported by Sandia. D. Yager-Elorriaga supported by NSF GF.

  14. Simulation of tectonic evolution of the Kanto basin of Japan since 1 Ma due to subduction of the Pacific and Philippine sea plates and collision of the Izu-Bonin arc

    NASA Astrophysics Data System (ADS)

    Hashima, Akinori; Sato, Toshinori; Sato, Hiroshi; Asao, Kazumi; Furuya, Hiroshi; Yamamoto, Shuji; Kameo, Koji; Miyauchi, Takahiro; Ito, Tanio; Tsumura, Noriko; Kaneda, Heitaro

    2015-04-01

    The Kanto basin, the largest lowland in Japan, developed by flexure as a result of (1) the subduction of the Philippine Sea (PHS) and the Pacific (PAC) plates and (2) the collision of the Izu-Bonin arc with the Japanese island arc. Geomorphological, geological, and thermochronological data on long-term vertical movements over the last 1 My suggest that subsidence initially affected the entire Kanto basin after which the area of subsidence gradually narrowed until, finally, the basin began to experience uplift. In this study, we modelled the tectonic evolution of the Kanto basin following the method of Matsu'ura and Sato (1989) for a kinematic subduction model with dislocations, in order to quantitatively assess the effects of PHS and PAC subduction. We include the steady slip-rate deficit (permanent locking rate at the plate interface) in our model to account for collision process. We explore how the arc-arc collision process has been affected by a westerly shift in the PHS plate motion vector with respect to the Eurasian plate, thought to have occurred between 1.0-0.5 Ma, using long-term vertical deformation data to constrain extent of the locked zone on the plate interface. We evaluated the change in vertical deformation rate for two scenarios: (1) a synchronous shift in the orientation of the locked zone as PHS plate motion shifts and (2) a delayed shift in the orientation of the locked zone following a change in plate motion. Observed changes in the subsidence/uplift pattern are better explained by scenario (2), suggesting that recent (<1 My) deformation in the Kanto basin shows a lag in crustal response to the shift in plate motion. We also calculated recent stress accumulation rates and found a good match with observed earthquake mechanisms, which shows that intraplate earthquakes serve to release stress accumulated through long-term plate interactions.

  15. Simulation of tectonic evolution of the Kanto Basin of Japan since 1 Ma due to subduction of the Pacific and Philippine Sea plates and the collision of the Izu-Bonin arc

    NASA Astrophysics Data System (ADS)

    Hashima, Akinori; Sato, Toshinori; Sato, Hiroshi; Asao, Kazumi; Furuya, Hiroshi; Yamamoto, Shuji; Kameo, Koji; Miyauchi, Takahiro; Ito, Tanio; Tsumura, Noriko; Kaneda, Heitaro

    2016-06-01

    The Kanto Basin, the largest lowland in Japan, developed by flexure as a result of (1) the subduction of the Philippine Sea (PHS) and the Pacific (PAC) plates and (2) the repeated collision of the Izu-Bonin arc fragments with the Japanese island arc. Geomorphological, geological, and thermochronological data on vertical movements over the last 1 My suggest that subsidence initially affected the entire basin after which the area of subsidence gradually narrowed until, finally, the basin began to experience uplift. In this study, we modeled the tectonic evolution of the Kanto Basin following the method of Matsu'ura and Sato (1989) for a kinematic subduction model with dislocations, in order to quantitatively assess the effects of PHS and PAC subduction. We include the steady slip-rate deficit (permanent locking rate at the plate interface) in our model to account for collision process. We explore how the latest collision of the Izu Peninsula block has been affected by a westerly shift in the PHS plate motion vector with respect to the Eurasian plate, thought to have occurred between 1.0-0.5 Ma, using long-term vertical deformation data to constrain extent of the locked zone on the plate interface. We evaluated the change in vertical deformation rate for two scenarios: (1) a synchronous shift in the orientation of the locked zone as PHS plate motion shifts and (2) a delayed shift in the orientation of the locked zone following the shift in plate motion. Observed changes in the uplift/subsidence pattern are better explained by scenario (2), suggesting that recent (< 1 My) deformation in the Kanto Basin shows a lag in crustal response to the plate motion shift. We also calculated stress accumulation rates and found a good match with observed earthquake mechanisms, which shows that intraplate earthquakes serve to release stress accumulated through long-term plate interactions.

  16. Energy transportation via MITL by the linear current flow density up to 7 MA/cm

    NASA Astrophysics Data System (ADS)

    Korolev, V. D.; Bakshaev, Yu. L.; Bartov, A. V.; Blinov, P. I.; Bryzgunov, V. A.; Chernenko, A. S.; Dan'ko, S. A.; Kalinin, Yu. G.; Kingsep, A. S.; Kazakov, E. D.; Smirnov, V. P.; Smirnova, E. A.; Ustroev, G. I.

    2006-10-01

    The transmission properties of the magnetically self-insulated vacuum transporting line (MITL) were studied on the S-300 pulsed power machine (3 MA, 100 ns) at the high linear current flow density up to dI/db = 7 MA/cm. Experiments were carried out with the short line sections with 10 ÷ 15 mm length and 3 ÷ 5 mm vacuum gap. For measuring of the plasma parameters, the frame ICT photography with the nanosecond temporal resolution in the SXR range and ICT (Image Converter Tube) chronography in visible range were used. The X-ray radiation in various ranges was recorded by the XRD with thin filters (SXR) and by the semiconductor detectors (HXR). The information about current transmission efficiency was obtained by means of magnetic loops and low-inductance shunt. It was determined that dense plasma arose on both anode and cathode when the linear current flow density was low enough, dI/db ≤ 1 MA/cm. A dense plasma moves across the vacuum gap with the velocity (1 ÷ 2) × 106 cm/s. By recording the current and hard X-ray radiation it was found that electron losses in the current front did not exceed 10 ÷ 100 kA. Under strong magnetization of electrons r H = mvc/eB < d, these losses could be due to the motion of fast plasma component, which velocity exceeds 107 cm/s. Such a rare plasma sheath formed on the cathode by dI/db ≥ 1 MA/cm. Thereby the successful physical modeling of the recyclable MITL related to the Sandia Laboratories’ Conceptual Project of fusion reactor on the base of fast Z-pinch has been brought about.

  17. Final Report: Radiation-magnetohydrodynamic evolution and instability of conductors driven by megagauss magnetic fields

    SciTech Connect

    Bauer, Bruno, S.; Siemon, Richard, E.

    2008-10-22

    We are pleased to report important progress in experimentally characterizing and numerically modeling the transformation into plasma of walls subjected to pulsed megagauss magnetic fields. Understanding this is important to Magnetized Target Fusion (MTF) because an important limitation to the metal liner approach to MTF comes from the strong eddy current heating on the surface of the metal liner. This has intriguing non-linear aspects when the magnetic field is in the megagauss regime as needed for MTF, and may limit the magnetic field in an MTF implosion. Many faculty, students, and staff have contributed to this work, and, implicitly or explicitly, to this report. Contributors include, in addition to the PIs, Andrey Esaulov, Stephan Fuelling, Irvin Lindemuth, Volodymyr Makhin, Ioana Paraschiv, Milena Angelova, Tom Awe, Tasha Goodrich, Arunkumar Prasadam, Andrew Oxner, Bruno Le Galloudec, Radu Presura, and Vladimir Ivanov. Highlights of the progress made during the grant include: • 12 articles published, and 44 conference and workshop presentations made, on a broad range of issues related to this project; • An ongoing experiment that uses the 1 MA, 100-ns Zebra z-pinch at UNR to apply 2 5 megagauss to a variety of metal surfaces, examining plasma formation and evolution; • Numerical simulation studies of the 1-MA Zebra, and potential Shiva Star and Atlas experiments that include realistic equations of state and radiation effects, using a variety of tables. • Collaboration with other groups doing simulations of this experiment at LANL, VNIIEF, SNL, and NumerEx leading to a successful international workshop at UNR in the spring of 2008.

  18. Implementing and diagnosing magnetic flux compression on the Z pulsed power accelerator

    SciTech Connect

    McBride, Ryan D.; Bliss, David E.; Gomez, Matthew R.; Hansen, Stephanie B.; Martin, Matthew R.; Jennings, Christopher Ashley; Slutz, Stephen A.; Rovang, Dean C.; Knapp, Patrick F.; Schmit, Paul F.; Awe, Thomas James; Hess, M. H.; Lemke, Raymond W.; Dolan, D. H.; Lamppa, Derek C.; Jobe, Marc Ronald Lee; Fang, Lu; Hahn, Kelly D.; Chandler, Gordon A.; Cooper, Gary Wayne; Ruiz, Carlos L.; Maurer, A. J.; Robertson, Grafton Kincannon; Cuneo, Michael E.; Sinars, Daniel; Tomlinson, Kurt; Smith, Gary; Paguio, Reny; Intrator, Tom; Weber, Thomas; Greenly, John

    2015-11-01

    and fabricating novel micro B-dot probes to measure B z ( t ) inside of an imploding liner. In one approach, the micro B-dot loops were fabricated on a printed circuit board (PCB). The PCB was then soldered to off-the-shelf 0.020- inch-diameter semi-rigid coaxial cables, which were terminated with standard SMA connectors. These probes were recently tested using the COBRA pulsed power generator (0-1 MA in 100 ns) at Cornell University. In another approach, we are planning to use new multi-material 3D printing capabilities to fabricate novel micro B-dot packages. In the near future, we plan to 3D print these probes and then test them on the COBRA generator. With successful operation demonstrated at 1-MA, we will then make plans to use these probes on a 20-MA Z experiment.

  19. Two dimensional triangulation of breakdown in a high voltage coaxial gap.

    PubMed

    Cordaro, S W; Bott-Suzuki, S C; Bendixsen, L S Caballero; Atoyan, Levon; Byvank, Tom; Potter, William; Kusse, B R; Greenly, J B

    2015-07-01

    We describe a technique by which magnetic field probes are used to triangulate the exact position of breakdown in a high voltage coaxial vacuum gap. An array of three probes is placed near the plane of the gap with each probe at 90° intervals around the outer (anode) electrode. These probes measure the azimuthal component of the magnetic field and are all at the same radial distance from the cylindrical axis. Using the peak magnetic field values measured by each probe, the current carried by the breakdown channel, and Ampères law we can calculate the distance away from each probe that the breakdown occurred. These calculated distances are then used to draw three circles each centered at the centers of the corresponding magnetic probes. The common intersection of these three circles then gives the predicted azimuthal location of the center of the breakdown channel. Test results first gathered on the coaxial gap breakdown device (240 A, 25 kV, 150 ns) at the University of California San Diego and then on COBRA (1 MA, 1 MV, 100 ns) at Cornell University indicate that this technique is relatively accurate and scales between these two devices.

  20. Magnetized plasma jets in experiment and simulation

    NASA Astrophysics Data System (ADS)

    Schrafel, Peter; Greenly, John; Gourdain, Pierre; Seyler, Charles; Blesener, Kate; Kusse, Bruce

    2013-10-01

    This research focuses on the initial ablation phase of a thing (20 micron) Al foil driven on the 1 MA-in-100 ns COBRA through a 5 mm diameter cathode in a radial configuration. In these experiments, ablated surface plasma (ASP) on the top of the foil and a strongly collimated axial plasma jet can be observed developing midway through current-rise. Our goal is to establish the relationship between the ASP and the jet. These jets are of interest for their potential relevance to astrophysical phenomena. An independently pulsed 200 μF capacitor bank with a Helmholtz coil pair allows for the imposition of a slow (150 μs) and strong (~1 T) axial magnetic field on the experiment. Application of this field eliminates significant azimuthal asymmetry in extreme ultraviolet emission of the ASP. This asymmetry is likely a current filamentation instability. Laser-backlit shadowgraphy and interferometry confirm that the jet-hollowing is correlated with the application of the axial magnetic field. Visible spectroscopic measurements show a doppler shift consistent with an azimuthal velocity in the ASP caused by the applied B-field. Computational simulations with the XMHD code PERSEUS qualitatively agree with the experimental results.

  1. Spectroscopy of Ablated Aluminum Foil Plasmas Driven by MA-LTD

    NASA Astrophysics Data System (ADS)

    Patel, S. G.; Zier, J. C.; Chalenski, D. A.; Gilgenbach, R. M.; Steiner, A. M.; Lau, Y. Y.

    2011-10-01

    Spectroscopic analysis has been performed on Al foil plasmas ablated by the Linear Transformer Driver (LTD) at the University of Michigan. The MAIZE LTD can supply 1- MA, 100 kV pulses with 100 ns risetime into a matched load. The plasma load consisted of a 400 nm thick Al foil (cathode) placed between two, planar, current-return anode posts. An optical fiber was placed 1 cm away from the load; plasma light passed through a 0.75-m optical spectrograph and was gated for 10 ns by an intensified CCD detector. The density of the edge plasma was determined through Stark broadening of the H-alpha line. The Fourier transform was taken of the Voigt profile, which was then used to approximate the density of the Al plasma. This method resulted in a density of approximately 1015 cm-3 in the outer regions of the Al plasma at peak current. Spectra taken midway in the current rise yielded 1-2 eV plasma temperatures from the slope of the continuum emission. These data will be shown as well as planned future experiments. Research sponsored by DoE, NSF and Sandia National Labs. S.G. Patel and J.C. Zier were supported by N.P.S.C. fellowships through Sandia National Laboratories.

  2. Finite Element Modeling for Megagauss Magnetic Field Generation

    NASA Astrophysics Data System (ADS)

    Martinez, David

    2005-10-01

    Applying external magnetic fields with MegaGauss strength is needed for hot plasma confinement and stabilization. We investigate the possibility of generating ultra-high magnetic fields with the fast z-pinch generator ``Zebra'' for experiments at the NTF. Zebra can produce a load a current of 1 MA in 100 ns. To design appropriate loads we use FemlabootnotetextFemlab 3 -- multi-physics, finite-element modeling program by Comsol AB, 2004 and ScreamerootnotetextScreamer -- A Pulsed Power Design Tool developed at SNL by M. L. Kiefer, K. L. Fugelso, K. W. Struve, and M. M. Widner. to simulate the magnetic field. Screamer predicts the load current using a detailed model of Zebra and helps optimize the operation. Using the information from Screamer, Femlab is able to calculate the magnetic field, heating, and stress on the conductor. All these effects must be taken into consideration to determine the integrity of the coil until maximum field is reached. The presentation will include simulation results for single- and multi-turn coils, as well as quasi-force-free inductors.

  3. X-ray Thomson Scattering using the Hybrid X-pinch X-ray Source

    NASA Astrophysics Data System (ADS)

    Hoyt, Cad; Pikuz, Sergei; Shelkovenko, Tania; Hammer, Dave

    2013-10-01

    Stringent photometric and bandwidth requirements have historically relegated X-ray Thomson scattering (XRTS) probe sources to high energy laser plasma sources or free electron lasers. Standard x-pinch configurations in which two or more fine wires cross and subtend an angle of about 30° forming an ``X'' between the anode and cathode of a pulsed power generatorcan produce extremely bright, subnanosecond bursts of continuum and line radiation from micron-scale sources. The hybrid x-pinch is a new configuration based on conical W-Cu alloy electrodes with a short 1-2 mm gap that is bridged by a fine wire resulting in an easier to load setup with improved performance characteristics. We explore the possibility of utilizing the hybid x-pinch as a novel XRTS probe source by examining certain spectral and temporal attributes of a range of materials in a hybrid x-pinch configuration on the XP (500 kA, 50 ns) and COBRA(1MA, 100ns) pulsed power generators. We find that a Ti hybrid x-pinch produces >1012 photons/sr in Ti He-alpha radiation and satisfies the noncollective scattering bandwidth requirement. Measurements of photon fluence, bandwidth and applicability to the relevant scattering regime and initial scattering results will be presented.

  4. HEMP-induced transients in transmission and distribution (T and D) lines

    SciTech Connect

    Engheta, N.; Lee, K.S.H.; Yang, F.C.; Aguero, R.

    1985-09-01

    The corona effects on the early-time induced transients on the transmission and distribution (T and D) lines are calculated based on two different corona models. Three different sources of excitation of the lines are considered, which include a HEMP plane wave, a localized voltage source, and a current injected at a point on the wire. The induced current and charge are calculated and compared with some available experimental data and with the results of Baum's model. The results illustrate that the corona generally reduces the peak value of the induced current as much as 30% of the value and decreases the rate of rise by about 40%. The HEMP-induced stresses across dielectric insulators in some typical electric power systems are also calculated. The insulators that are considered are line supports in T and D line poles, and transformer bushings in distribution and power transformers. Different elevation and azimuthal angles of HEMP incidence with two different values of ground conductivity are considered. The HEMP-induced ''potential difference'' across the line support and air gap in the transmission lines and the HEMP-induced open-circuit voltage across transformer bushings are calculated. The ''potential difference'' across the line support and across the air gap can be as high as 7 MV. The rise time of the ''potential difference'' is about 110 ns, and the fall time is about 2 to 3 ..mu..s. The open-circuit voltage across transformer bushings can be as large as few tens of MVs and the rise time is in the order of 100 ns and the fall time 800 ns.

  5. Interplay of classical and quantum dynamics in a thermal ensemble of atoms

    NASA Astrophysics Data System (ADS)

    Warsi Laskar, Arif; Singh, Niharika; Mukherjee, Arunabh; Ghosh, Saikat

    2016-05-01

    In a thermal ensemble of atoms driven by coherent fields, how does evolution of quantum superposition compete with classical dynamics of optical pumping and atomic diffusion? Is it optical pumping that first prepares a thermal ensemble, with coherent superposition developing subsequently or is it the other way round: coherently superposed atoms driven to steady state via optical pumping? Using a stroboscopic probing technique, here we experimentally explore these questions. A 100 ns pulse is used to probe an experimentally simulated, closed three-level, Λ-like configuration in rubidium atoms, driven by strong coherent (control) and incoherent fields. Temporal evolution of probe transmission shows an initial overshoot with turn-on of control, resulting in a scenario akin to lasing without inversion. The corresponding rise time is dictated by coherent dynamics, with a distinct experimental signature of half-cycle Rabi flop in a thermal ensemble of atoms. Our results indicate that, in fact, optical pumping drives the atoms to a steady state in a significantly longer time-scale that sustains superposed dark states. Eventual control turn-off leads to a sudden fall in transmission with an ubiquitous signature for identifying closed and open systems. Numerical simulations and toy-model predictions confirm our claims. These studies reveal new insights into a rich and complex dynamics associated with atoms in thermal ensemble, which are otherwise absent in state-prepared, cold atomic ensembles.

  6. Experimental demonstration of fusion-relevant conditions in magnetized liner inertial fusion

    SciTech Connect

    Gomez, Matthew R.; Slutz, Stephen A..; Sefkow, Adam B.; Sinars, Daniel B.; Hahn, Kelly D.; Hansen, Stephanie B.; Harding, Eric C.; Knapp, Patrick F.; Schmit, Paul F.; Jennings, Christopher A.; Awe, Thomas James; Geissel, Matthias; Rovang, Dean C.; Chandler, Gordon A.; Cooper, Gary Wayne; Cuneo, Michael Edward; Harvey-Thompson, Adam James; Herrmann, Mark; Hess, M. H.; Johns, Owen; Lamppa, Derek C.; Martin, Matthew R.; McBride, Ryan D.; Peterson, Kyle J.; Porter, John L.; Robertson, Grafton Kincannon; Rochau, Gregory A.; Ruiz, Carlos L.; Savage, Mark E.; Smith, Ian C.; Stygar, William A.; Vesey, Roger A.

    2014-10-06

    This Letter presents results from the first fully integrated experiments testing the magnetized liner inertial fusion concept [S.A. Slutz et al., Phys. Plasmas 17, 056303 (2010)], in which a cylinder of deuterium gas with a preimposed axial magnetic field of 10 T is heated by Z beamlet, a 2.5 kJ, 1 TW laser, and magnetically imploded by a 19 MA current with 100 ns rise time on the Z facility. Despite a predicted peak implosion velocity of only 70 km/s, the fuel reaches a stagnation temperature of approximately 3 keV, with Te ≈ Ti, and produces up to 2e12 thermonuclear DD neutrons. In this study, X-ray emission indicates a hot fuel region with full width at half maximum ranging from 60 to 120 μm over a 6 mm height and lasting approximately 2 ns. The number of secondary deuterium-tritium neutrons observed was greater than 1010, indicating significant fuel magnetization given that the estimated radial areal density of the plasma is only 2 mg/cm2.

  7. Experimental demonstration of fusion-relevant conditions in magnetized liner inertial fusion

    DOE PAGES

    Gomez, Matthew R.; Slutz, Stephen A..; Sefkow, Adam B.; Sinars, Daniel B.; Hahn, Kelly D.; Hansen, Stephanie B.; Harding, Eric C.; Knapp, Patrick F.; Schmit, Paul F.; Jennings, Christopher A.; et al

    2014-10-06

    This Letter presents results from the first fully integrated experiments testing the magnetized liner inertial fusion concept [S.A. Slutz et al., Phys. Plasmas 17, 056303 (2010)], in which a cylinder of deuterium gas with a preimposed axial magnetic field of 10 T is heated by Z beamlet, a 2.5 kJ, 1 TW laser, and magnetically imploded by a 19 MA current with 100 ns rise time on the Z facility. Despite a predicted peak implosion velocity of only 70 km/s, the fuel reaches a stagnation temperature of approximately 3 keV, with Te ≈ Ti, and produces up to 2e12 thermonuclearmore » DD neutrons. In this study, X-ray emission indicates a hot fuel region with full width at half maximum ranging from 60 to 120 μm over a 6 mm height and lasting approximately 2 ns. The number of secondary deuterium-tritium neutrons observed was greater than 1010, indicating significant fuel magnetization given that the estimated radial areal density of the plasma is only 2 mg/cm2.« less

  8. Experimental Demonstration of Fusion-Relevant Conditions in Magnetized Liner Inertial Fusion

    NASA Astrophysics Data System (ADS)

    Gomez, M. R.; Slutz, S. A.; Sefkow, A. B.; Sinars, D. B.; Hahn, K. D.; Hansen, S. B.; Harding, E. C.; Knapp, P. F.; Schmit, P. F.; Jennings, C. A.; Awe, T. J.; Geissel, M.; Rovang, D. C.; Chandler, G. A.; Cooper, G. W.; Cuneo, M. E.; Harvey-Thompson, A. J.; Herrmann, M. C.; Hess, M. H.; Johns, O.; Lamppa, D. C.; Martin, M. R.; McBride, R. D.; Peterson, K. J.; Porter, J. L.; Robertson, G. K.; Rochau, G. A.; Ruiz, C. L.; Savage, M. E.; Smith, I. C.; Stygar, W. A.; Vesey, R. A.

    2014-10-01

    This Letter presents results from the first fully integrated experiments testing the magnetized liner inertial fusion concept [S. A. Slutz et al., Phys. Plasmas 17, 056303 (2010)], in which a cylinder of deuterium gas with a preimposed 10 T axial magnetic field is heated by Z beamlet, a 2.5 kJ, 1 TW laser, and magnetically imploded by a 19 MA, 100 ns rise time current on the Z facility. Despite a predicted peak implosion velocity of only 70 km/s, the fuel reaches a stagnation temperature of approximately 3 keV, with Te≈Ti, and produces up to 2×1012 thermonuclear deuterium-deuterium neutrons. X-ray emission indicates a hot fuel region with full width at half maximum ranging from 60 to 120 μm over a 6 mm height and lasting approximately 2 ns. Greater than 1010 secondary deuterium-tritium neutrons were observed, indicating significant fuel magnetization given that the estimated radial areal density of the plasma is only 2 mg/cm2.

  9. Z: A Fast Pulsed Power Generator for Ultra-High Magnetic Field Generation

    SciTech Connect

    Asay, J.R.; Bailey, J.E.; Bernard, M.A.; Hall, C.A.; McDaniel, D.H.; Spielman, R.B.; Struve, K.W.; Stygar, W.A.

    1998-11-04

    Advances in fast, pulsed-power technologies have resulted in the development of very high current drivers that have current rise times - 100 ns. The largest such pulsed power drive r today is the new Z accelerator located at Sandia National Laboratories in Albuquerque, New Mexico. Z is capable of delivering more than 20 MA with a time-to-peak of 105 ns to low inductance (- 1 nH)loads. Such large drivers are capable of directly generating magnetic fields approaching 3 kT in small, 1 -cm3, volumes. In addition to direct field generation, Z can be used to compress an applied, axial seed field with a plasma. Flux compression scheme~: are not new and are, in fact, the basis of all explosive flux-compression generators but we propose the use of plasma armatures rather than solid, conducting armatures. We will present experimental results from the Z accelerator in which magnetic fields - 2 kT are generated and measured with several diagnostics. Issues such as energy loss in solid conductors and dynamic response of current-carrying conductors to very large magnetic fields will be reviewed in context with Z experiments. We will describe planned flux-compression experiments that are expected to create the highest-magnitude uniform-field volumes yet attained in the laboratory.

  10. Plasma shells compression on Angara-5-1

    NASA Astrophysics Data System (ADS)

    Grabovsky, E. V.; Nedoseev, S. L.; Oleynic, G. M.; Samohin, A. A.; Sasorov, Pavel V.; Smirnov, V. P.; Fedulov, M. V.; Alecsandrov, V. V.; Volkov, Georgi S.; Zurin, M. V.; Frolov, I. N.; Zukakishvili, G. G.

    2001-04-01

    Appearance of generators of electric power of pulse duration of about 100 ns opened new possibilities in classic Z- pinches. First, it is connected with new level of power of this generators. Second, it has become possible to use loads of another size and densities. One of the new tasks studied on powerful installations is generation is generation of pulses of soft x-ray radiation for thermonuclear fusion research. The models of target ignition, developed on systems of laser initiation, determined the nanosecond time as a characteristic time scale of radiation pulse. A program of fast liner compression is developing in TRINITI on Angara 5-1 installation- an 8 module pulse generator of max power of 9TW, pulse rise time of 90 ns, load peak current of 4 MA. The main aim of the program was to investigate a way to create a source of soft x-ray radiation of high intensity for thermonuclear fusion and fundamental research work. A conception of double liner were proposed as a perspective way to ensure a dynamic hohlraum for thermonuclear target irradiation.

  11. Magnetic Field Measurements in Wire-Array Z-Pinches using Magneto-Optically Active Waveguides

    NASA Astrophysics Data System (ADS)

    Syed, Wasif; Hammer, David; Lipson, Michal

    2007-11-01

    Understanding the magnetic field topology in wire-array Z-pinches as a function of time is of great significance to understanding these high-energy density plasmas. We are developing techniques to measure magnetic fields as a function of space and time using Faraday rotation of a single longitudinal mode (SLM) laser through a magneto-optically active bulk waveguide (terbium borate glass) placed adjacent to, or within, the wire array in experiments on the COBRA pulsed power generator [1]. We have measured fields >10 T with 100 ns rise times outside of a wire-array for the entire duration of the current pulse and as much as ˜2 T inside a wire-array for ˜40 ns from the start of current. This is the first time that such rapidly varying and large fields have been measured using these materials. We will also present our progress on field measurements using an optical fiber sensor and a very small ``thin film waveguide'' coupled to a fiber optic system. In a dense Z-pinch, these sensing devices may not survive for long but may provide the magnetic field at the position of the sensor for a greater fraction of the current pulse than magnetic probes, with which we compare our results. This research was sponsored by NNSA under SSAA program via DOE Coop Agreement DE-F03-02NA00057. [1] W. Syed, D. A. Hammer, & M. Lipson, 34^th ICOPS & 16^th PPPS, Albuquerque, NM, June 2007.

  12. A repetitive long-pulse power generator based on pulse forming network and linear transformer driver.

    PubMed

    Li, Mingjia; Kang, Qiang; Tan, Jie; Zhang, Faqiang; Luo, Min; Xiang, Fei

    2016-06-01

    A compact module for long-pulse power generator, based on Blumlein pulse forming network (PFN), was designed. Two Blumlein PFNs with L-type configuration and 20 Ω characteristic impedance were connected symmetrically to the primary coil of the linear transformer driver (LTD) and driven by an identical high voltage spark switch to ensure two Blumlein PFNs synchronizing operation. The output pulse of the module connected with 10 Ω water load is about 135 kV in amplitude and 200 ns in duration with a rise time of ∼50 ns and a flat top of ∼100 ns. On this basis, a repetitive long-pulse power generator based on PFN-LTD has been developed, which was composed of four modules. The following technical parameters of the generator were achieved on planar diode: output voltage amplitude of ∼560 kV, output current amplitude of ∼10 kA at a repetition rate of 25 Hz. The generator operates stable and outputs more than 10(4) pulses. Meanwhile, the continuous operating time of the generator is up to 60 s. PMID:27370479

  13. Induction technology optimization code

    SciTech Connect

    Caporaso, G.J.; Brooks, A.L.; Kirbie, H.C.

    1992-08-21

    A code has been developed to evaluate relative costs of induction accelerator driver systems for relativistic klystrons. The code incorporates beam generation, transport and pulsed power system constraints to provide an integrated design tool. The code generates an injector/accelerator combination which satisfies the top level requirements and all system constraints once a small number of design choices have been specified (rise time of the injector voltage and aspect ratio of the ferrite induction cores, for example). The code calculates dimensions of accelerator mechanical assemblies and values of all electrical components. Cost factors for machined parts, raw materials and components are applied to yield a total system cost. These costs are then plotted as a function of the two design choices to enable selection of an optimum design based on various criteria. The Induction Technology Optimization Study (ITOS) was undertaken to examine viable combinations of a linear induction accelerator and a relativistic klystron (RK) for high power microwave production. It is proposed, that microwaves from the RK will power a high-gradient accelerator structure for linear collider development. Previous work indicates that the RK will require a nominal 3-MeV, 3-kA electron beam with a 100-ns flat top. The proposed accelerator-RK combination will be a high average power system capable of sustained microwave output at a 300-Hz pulse repetition frequency. The ITOS code models many combinations of injector, accelerator, and pulse power designs that will supply an RK with the beam parameters described above.

  14. Hybrid X-pinches

    SciTech Connect

    Shelkovenko, T. A.; Pikuz, S. A.; Mishin, S. A.; Mingaleev, A. R.; Tilikin, I. N.; Knapp, P. F.; Cahill, A. D.; Hoyt, C. L.; Hammer, D. A.

    2012-05-15

    Results from experimental studies of a hybrid X-pinch with an initial configuration in the form of a high-current diode with conical tungsten electrodes spaced by 1-2 mm and connected to one another with 20- to 100-{mu}m-diameter wires are presented. The experiments were carried out at four facilities with a current amplitude from 200 to 1000 kA and front duration from 45 to 200 ns. It is shown that, in spite of their simpler configuration, hybrid X-pinches with a short rise time of the current pulse (50-100 ns) are highly competitive with standard X-pinches in the generated soft X-ray power and the formation of a single hot spot in them is much more stable, while hard X-ray emission is almost absent. The possibility of using hybrid X-pinches as soft X-ray sources for point projection X-ray imaging of plasma objects is considered.

  15. Improvement of Spatial Uniformity of Nanosecond-Pulse Diffuse Discharges in a Multi-Needle-to-Plane Gap

    NASA Astrophysics Data System (ADS)

    Gu, Jianwei; Zhang, Cheng; Wang, Ruixue; Yan, Ping; Shao, Tao

    2016-03-01

    Large-scale non-thermal plasmas generated by nanosecond-pulse discharges have been used in various applications, including surface treatment, biomedical treatment, flow control etc. In this paper, atmospheric-pressure diffuse discharge was produced by a homemade nanosecond-pulse generator with a full width at half maximum of 100 ns and a rise time of 70 ns. In order to increase the discharge area, multi-needle electrodes with a 3×3 array were designed. The electrical characteristics of the diffuse discharge array and optical images were investigated by the voltage-current waveforms and discharge images. The experimental results showed that the intensity of diffuse discharges in the center was significantly weaker than those at the margins, resulting in an inhomogeneous spatial uniformity in the diffuse discharge array. Simulation of the electric field showed that the inhomogeneous spatial uniformity was caused by the non-uniform distribution of the electric field in the diffuse discharge array. Moreover, the spatial uniformity of the diffuse discharge array could be improved by increasing the length of the needle in the centre of the array. Finally, the experimental results confirmed the simulation results, and the spatial uniformity of the nanosecond-pulse diffuse discharge array was significantly improved. supported by National Natural Science Foundation of China (Nos. 51222701, 51477164) and the National Basic Research Program of China (No. 2014CB239505-3)

  16. A repetitive long-pulse power generator based on pulse forming network and linear transformer driver

    NASA Astrophysics Data System (ADS)

    Li, Mingjia; Kang, Qiang; Tan, Jie; Zhang, Faqiang; Luo, Min; Xiang, Fei

    2016-06-01

    A compact module for long-pulse power generator, based on Blumlein pulse forming network (PFN), was designed. Two Blumlein PFNs with L-type configuration and 20 Ω characteristic impedance were connected symmetrically to the primary coil of the linear transformer driver (LTD) and driven by an identical high voltage spark switch to ensure two Blumlein PFNs synchronizing operation. The output pulse of the module connected with 10 Ω water load is about 135 kV in amplitude and 200 ns in duration with a rise time of ˜50 ns and a flat top of ˜100 ns. On this basis, a repetitive long-pulse power generator based on PFN-LTD has been developed, which was composed of four modules. The following technical parameters of the generator were achieved on planar diode: output voltage amplitude of ˜560 kV, output current amplitude of ˜10 kA at a repetition rate of 25 Hz. The generator operates stable and outputs more than 104 pulses. Meanwhile, the continuous operating time of the generator is up to 60 s.

  17. Immobilization and hybridization by single sub-millisecond electric field pulses, for pixel-addressed DNA microarrays.

    PubMed

    Fixe, F; Branz, H M; Louro, N; Chu, V; Prazeres, D M F; Conde, J P

    2004-07-15

    Single square voltage pulses applied to buried electrodes result in dramatic rate increases for (1) selective covalent bonding (immobilization) of single-stranded DNA (ssDNA) probes to a functionalized thin film SiO(2) surface on a plastic substrate and (2) hybridization of ssDNA to the immobilized probe. DNA immobilization and hybridization times are 100 ns and 10 micros, respectively, about 10(9) times faster than the corresponding passive reactions without electric field. Surface coverage is comparable. Duration, magnitude and slew rate of the voltage pulse are all key factors controlling the rates of ssDNA immobilization and hybridization. With rise times of 4.5 ns, pulses shorter than 1 ms and voltages below 1V are effective. The ssDNA adsorbed on the surface is reoriented by the rapidly changing electric field. This reduces steric barriers and speeds the immobilization and hybridization reactions. These results open the way for pixel-addressed microarrays driven by silicon microelectronics circuits. PMID:15142592

  18. A repetitive long-pulse power generator based on pulse forming network and linear transformer driver.

    PubMed

    Li, Mingjia; Kang, Qiang; Tan, Jie; Zhang, Faqiang; Luo, Min; Xiang, Fei

    2016-06-01

    A compact module for long-pulse power generator, based on Blumlein pulse forming network (PFN), was designed. Two Blumlein PFNs with L-type configuration and 20 Ω characteristic impedance were connected symmetrically to the primary coil of the linear transformer driver (LTD) and driven by an identical high voltage spark switch to ensure two Blumlein PFNs synchronizing operation. The output pulse of the module connected with 10 Ω water load is about 135 kV in amplitude and 200 ns in duration with a rise time of ∼50 ns and a flat top of ∼100 ns. On this basis, a repetitive long-pulse power generator based on PFN-LTD has been developed, which was composed of four modules. The following technical parameters of the generator were achieved on planar diode: output voltage amplitude of ∼560 kV, output current amplitude of ∼10 kA at a repetition rate of 25 Hz. The generator operates stable and outputs more than 10(4) pulses. Meanwhile, the continuous operating time of the generator is up to 60 s.

  19. Experimental demonstration of fusion-relevant conditions in magnetized liner inertial fusion.

    PubMed

    Gomez, M R; Slutz, S A; Sefkow, A B; Sinars, D B; Hahn, K D; Hansen, S B; Harding, E C; Knapp, P F; Schmit, P F; Jennings, C A; Awe, T J; Geissel, M; Rovang, D C; Chandler, G A; Cooper, G W; Cuneo, M E; Harvey-Thompson, A J; Herrmann, M C; Hess, M H; Johns, O; Lamppa, D C; Martin, M R; McBride, R D; Peterson, K J; Porter, J L; Robertson, G K; Rochau, G A; Ruiz, C L; Savage, M E; Smith, I C; Stygar, W A; Vesey, R A

    2014-10-10

    This Letter presents results from the first fully integrated experiments testing the magnetized liner inertial fusion concept [S. A. Slutz et al., Phys. Plasmas 17, 056303 (2010)], in which a cylinder of deuterium gas with a preimposed 10 Taxial magnetic field is heated by Z beamlet, a 2.5 kJ, 1 TW laser, and magnetically imploded by a 19 MA, 100 ns rise time current on the Z facility. Despite a predicted peak implosion velocity of only 70 km = s, the fuel reaches a stagnation temperature of approximately 3 keV, with T(e) ≈ T(i), and produces up to 2 x 10(12) thermonuclear deuterium-deuterium neutrons. X-ray emission indicates a hot fuel region with full width at half maximum ranging from 60 to 120 μm over a 6 mm height and lasting approximately 2 ns. Greater than 10(10) secondary deuterium-tritium neutrons were observed, indicating significant fuel magnetization given that the estimated radial areal density of the plasma is only 2 mg = cm(2). PMID:25375714

  20. Diffusion of fast rising strong magnetic fields into conductors

    NASA Astrophysics Data System (ADS)

    Labetskaya, N. A.; Oreshkin, V. I.; Chaikovsky, S. A.; Datsko, I. M.; Kuskova, N. I.; Rud, A. D.

    2014-11-01

    The basic processes occurring in a conductor exploding in a current skinning mode are the propagation of a nonlinear magnetic diffusion wave in the conductor and the formation of low-temperature plasma at its surface. An experimental study of the phenomenon of nonlinear magnetic diffusion into conductors in magnetic fields of induction rising at a rate up to 3·109 T/s was carried out on the MIG generator capable of producing a peak current up to 2.5 MA within a rise time of 100 ns. It has been found experimentally that the average velocity of a nonlinear magnetic diffusion wave in an aluminum conductor placed in a strong magnetic field (up to 300 T) rising at a high rate (on average, 3·109 T/s) is (2.7÷3.3)·105 cm/s. This is comparable to the velocity of sound in aluminum under normal conditions and reasonably agrees with predictions of numerical simulations.

  1. Soldered Contact and Current Risetime Effects on Negative Polarity Wire Array Z-pinches

    SciTech Connect

    Chalenski, D. A.; Kusse, B. R.; Greenly, J. B.; Blesener, I. C.; McBride, R. D.; Hammer, D. A.; Knapp, P. F.

    2009-01-21

    The Cornell University COBRA pulser is a nominal 1 MA machine, capable of driving up to 32 wire cylindrical Z-pinch arrays. COBRA can operate with variable current risetimes ranging from 100 ns to 200 ns (short and long pulse, respectively). Wires are typically strung with a 'press' contact to the electrode hardware, where the wire is loosely pulled against the hardware and held there to establish electrical contact. The machine is normally negative, but a bolt-on convolute can be used to modify the current path and effectively produce positive polarity operation at the load.Previous research with single wires on a 1-5 kA pulser has shown that soldering the wire, thereby improving the wire/electrode contact, and operating in positive polarity can improve the energy deposition into the wire and enhance wire core expansion. Negative polarity showed no difference. Previous experiments on the negative polarity, 20 MA, 100 ns Z accelerator have shown that improving the contact improved the x-ray yield.Cornell data were collected on 16-wire Aluminum Z-pinch arrays in negative polarity. Experiments were conducted with both short and long current pulses with soldered and no-soldered wire/electrode contacts. The initiation, ablation, implosion and stagnation phases were compared for these four conditions. Time dependent x-ray signals were measured using diodes and diamond detectors. An inductive voltage monitor was used to infer minimum current radius achieved, as defined by a uniform shell of current moving radially inward, producing a time dependent inductance. Total energy data were collected with a metal-strip bolometer. Self-emission data were collected by an XUV 4-frame camera and an optical streak camera.In negative polarity and with short pulses, soldering appeared to produce a smaller radius pinch and decrease variations in the x-ray pulse shape. The bolometer, laser backlighter, 4-frame and streak cameras showed negligible differences in the initiation ablation

  2. Long term survival of mice with hepatocellular carcinoma after pulse power ablation with nanosecond pulsed electric fields.

    PubMed

    Chen, X; Zhuang, J; Kolb, J F; Schoenbach, K H; Beebe, S J

    2012-02-01

    Novel therapies are needed for treating hepatocellular carcinoma (HCC) without recurrence in a single procedure. In this work we evaluated anti-neoplastic effects of a pulse power ablation (PPA) with nanosecond pulsed electric fields (nsPEFs), a non-thermal, non-drug, local, regional method and investigated its molecular mechanisms for hepatocellular carcinoma tumor ablation in vivo. An ectopic tumor model was established using C57BL/6 mice with Hepa1-6 hepatocellular carcinoma cells. Pulses with durations of 30 or 100 ns and fast rise times were delivered by a needle or ring electrode with different electric field strengths (33, 50 and 68 kV/cm), and 900 pulses in three treatment sessions (300 pulses each session) or a single 900 pulse treatment. Treated and control tumor volumes were monitored by ultrasound and apoptosis and angiogenesis markers were evaluated by immunohistochemistry. Seventy five percent of primary hepatocellular carcinoma tumors were eradicated with 900 hundred pulses at 100 ns pulses at 68 kV/cm in a single treatment or in three treatment sessions without recurrence within 9 months. Using quantitative analysis, tumors in treated animals showed nsPEF-mediated nuclear condensation (3 h post-pulse), cell shrinkage (1 h), increases in active executioner caspases (caspase-3 > -7 > -6) and terminal deoxynucleotidyl transferase dUTP nick-end-labeling (1 h) with decreases in vascular endothelial growth factor expression (7d) and micro-vessel density (14d). NsPEF ablation eliminated hepatocellular carcinoma tumors by targeting two therapeutic sites, apoptosis induction and inhibition of angiogenesis, both important cancer hallmarks. These data indicate that PPA with nsPEFs is not limited to treating skin cancers and provide a rationale for continuing to investigate pulse power ablation for hepatocellular carcinoma using other models in pre-clinical applications and ultimately in clinical trials. Based on present treatments for specific HCC stages, it

  3. Technique for fabrication of ultrathin foils in cylindrical geometry for liner-plasma implosion experiments with sub-megaampere currents.

    PubMed

    Yager-Elorriaga, D A; Steiner, A M; Patel, S G; Jordan, N M; Lau, Y Y; Gilgenbach, R M

    2015-11-01

    In this work, we describe a technique for fabricating ultrathin foils in cylindrical geometry for liner-plasma implosion experiments using sub-MA currents. Liners are formed by wrapping a 400 nm, rectangular strip of aluminum foil around a dumbbell-shaped support structure with a non-conducting center rod, so that the liner dimensions are 1 cm in height, 6.55 mm in diameter, and 400 nm in thickness. The liner-plasmas are imploded by discharging ∼600 kA with ∼200 ns rise time using a 1 MA linear transformer driver, and the resulting implosions are imaged four times per shot using laser-shadowgraphy at 532 nm. This technique enables the study of plasma implosion physics, including the magneto Rayleigh-Taylor, sausage, and kink instabilities on initially solid, imploding metallic liners with university-scale pulsed power machines. PMID:26628134

  4. Technique for fabrication of ultrathin foils in cylindrical geometry for liner-plasma implosion experiments with sub-megaampere currents

    SciTech Connect

    Yager-Elorriaga, D. A.; Steiner, A. M.; Patel, S. G.; Jordan, N. M.; Lau, Y. Y.; Gilgenbach, R. M.

    2015-11-19

    In this study, we describe a technique for fabricating ultrathin foils in cylindrical geometry for liner-plasma implosion experiments using sub-MA currents. Liners are formed by wrapping a 400 nm, rectangular strip of aluminum foil around a dumbbell-shaped support structure with a non-conducting center rod, so that the liner dimensions are 1 cm in height, 6.55 mm in diameter, and 400 nm in thickness. The liner-plasmas are imploded by discharging ~600 kA with ~200 ns rise time using a 1 MA linear transformer driver, and the resulting implosions are imaged four times per shot using laser-shadowgraphy at 532 nm. As a result, this technique enables the study of plasma implosion physics, including the magneto Rayleigh-Taylor, sausage, and kink instabilities on initially solid, imploding metallic liners with university-scale pulsed power machines.

  5. Technique for fabrication of ultrathin foils in cylindrical geometry for liner-plasma implosion experiments with sub-megaampere currents

    DOE PAGES

    Yager-Elorriaga, D. A.; Steiner, A. M.; Patel, S. G.; Jordan, N. M.; Lau, Y. Y.; Gilgenbach, R. M.

    2015-11-19

    In this study, we describe a technique for fabricating ultrathin foils in cylindrical geometry for liner-plasma implosion experiments using sub-MA currents. Liners are formed by wrapping a 400 nm, rectangular strip of aluminum foil around a dumbbell-shaped support structure with a non-conducting center rod, so that the liner dimensions are 1 cm in height, 6.55 mm in diameter, and 400 nm in thickness. The liner-plasmas are imploded by discharging ~600 kA with ~200 ns rise time using a 1 MA linear transformer driver, and the resulting implosions are imaged four times per shot using laser-shadowgraphy at 532 nm. As amore » result, this technique enables the study of plasma implosion physics, including the magneto Rayleigh-Taylor, sausage, and kink instabilities on initially solid, imploding metallic liners with university-scale pulsed power machines.« less

  6. Technique for fabrication of ultrathin foils in cylindrical geometry for liner-plasma implosion experiments with sub-megaampere currents

    NASA Astrophysics Data System (ADS)

    Yager-Elorriaga, D. A.; Steiner, A. M.; Patel, S. G.; Jordan, N. M.; Lau, Y. Y.; Gilgenbach, R. M.

    2015-11-01

    In this work, we describe a technique for fabricating ultrathin foils in cylindrical geometry for liner-plasma implosion experiments using sub-MA currents. Liners are formed by wrapping a 400 nm, rectangular strip of aluminum foil around a dumbbell-shaped support structure with a non-conducting center rod, so that the liner dimensions are 1 cm in height, 6.55 mm in diameter, and 400 nm in thickness. The liner-plasmas are imploded by discharging ˜600 kA with ˜200 ns rise time using a 1 MA linear transformer driver, and the resulting implosions are imaged four times per shot using laser-shadowgraphy at 532 nm. This technique enables the study of plasma implosion physics, including the magneto Rayleigh-Taylor, sausage, and kink instabilities on initially solid, imploding metallic liners with university-scale pulsed power machines.

  7. Strategy for stabilization of the antiferroelectric phase (Pbma) over the metastable ferroelectric phase (P2{sub 1}ma) to establish double loop hysteresis in lead-free (1−x)NaNbO{sub 3}-xSrZrO{sub 3} solid solution

    SciTech Connect

    Guo, Hanzheng Randall, Clive A.; Shimizu, Hiroyuki; Mizuno, Youichi

    2015-06-07

    A new lead-free antiferroelectric solid solution system, (1−x)NaNbO{sub 3}-xSrZrO{sub 3}, was rationalized through noting the crystal chemistry trend, of decreasing the tolerance factor and an increase in the average electronegativity of the system. The SrZrO{sub 3} doping was found to effectively stabilize the antiferroelectric (P) phase in NaNbO{sub 3} without changing its crystal symmetry. Preliminary electron diffraction and polarization measurements were presented which verified the enhanced antiferroelectricity. In view of our recent report of another lead-free antiferroelectric system (1−x)NaNbO{sub 3}-xCaZrO{sub 3} [H. Shimizu et al. “Lead-free antiferroelectric: xCaZrO{sub 3} - (1−x)NaNbO{sub 3} system (0 ≤ x ≤ 0.10),” Dalton Trans. (published online)], the present results point to a general strategy of utilizing tolerance factor to develop a broad family of new lead-free antiferroelectrics with double polarization hysteresis loops. We also speculate on a broad family of possible solid solutions that could be identified and tested for this important type of dielectric.

  8. Characterization of the magnetization reversal of perpendicular Nanomagnetic Logic clocked in the ns-range

    NASA Astrophysics Data System (ADS)

    Ziemys, Grazvydas; Trummer, Christian; Gamm, Stephan Breitkreutz-v.; Eichwald, Irina; Schmitt-Landsiedel, Doris; Becherer, Markus

    2016-05-01

    We have investigated the magnetization reversal of fabricated Co/Pt nanomagnets with perpendicular anisotropy within a wide range of magnetic field pulse widths. This experiment covers the pulse lengths from 700 ms to 20 ns. We observed that the commonly used Arrhenius model fits very well the experimental data with a single parameter set for pulse times above 100 ns (tp > 100 ns). However, below 100 ns (tp < 100 ns), a steep increase of the switching field amplitude is observed and the deviation from the Arrhenius model becomes unacceptable. For short pulse times the model can be adjusted by the reversal time term for the dynamic switching field which is only dependent on the pulse amplitude and not on temperature anymore. Precise modeling of the magnetization reversal in the sub-100 ns-range is crucially important to ensure reliable operation in the favored GHz-range as well as to explore and design new kinds of Nanomagnetic Logic circuits and architectures.

  9. Nanosecond-pulse gliding discharges between point-to-point electrodes in open air

    NASA Astrophysics Data System (ADS)

    Zhang, Cheng; Shao, Tao; Yan, Ping; Zhou, Yuanxiang

    2014-06-01

    In this paper, gliding discharges with a point-to-point electrode geometry were produced by a repetitively pulsed power supply with a rise time of ˜100 ns and a full-width at half-maximum of ˜200 ns. The characteristics of such discharges were investigated by measuring their voltage-current waveforms and taking photographs of their discharge images. Experimental results showed that once the breakdown occurred, the nanosecond-pulse gliding discharges went into a stable stage at all air gaps, behaving in a mode of repetitive sparks. Under certain conditions, a non-stable stage would appear some time after the discharge went into the stable stage, in which the gliding discharges transitioned from repetitive sparks to diffuse discharges. Furthermore, several factors (gap spacing, pulse repetition frequency (PRF) and gas flow rate) influencing the discharge characteristics were investigated. It was observed that both the breakdown voltage and ignition voltage increased with the gap spacing, and a diffuse discharge was absent when the gap spacing was less than 6 mm. The breakdown voltage decreased with the increase in the PRF and its decrease ratio was larger in large gap spacing than in small gap spacing. Discharges would transit from repetitive sparks to diffuse discharges as the flow rate increased. Furthermore, a comparison of nanosecond-pulse and ac gliding discharges was conducted with respect to the power supply. The consumption and energy, the relationship between the power supply and the load, and the time interval between two pulses were three main factors which could lead to different characteristics between the nanosecond-pulse and ac gliding discharges.

  10. Wire Array Z-pinches on Sphinx Machine: Experimental Results and Relevant Points of Microsecond Implosion Physics

    SciTech Connect

    Calamy, H.; Hamann, F.; Lassalle, F.; Bayol, F.; Mangeant, C.; Morell, A.; Huet, D.; Bedoch, J.P.; Chittenden, J.P.; Lebedev, S.V.; Jennings, C.A.; Bland, S.N.

    2006-01-05

    Centre d'Etudes de Gramat (France) has developed an efficient long implosion time (800 ns) Aluminum plasma radiation source (PRS). Based on the LTD technology, the SPHINX facility is developed as a 1-3MJ, 1{mu}s rise time, 4-10 MA current driver. In this paper, it was used in 1MJ, 4MA configuration to drive Aluminum nested wire arrays Z-pinches with K-shell yield up to 20 kJ and a FWHM of the x-ray pulse of about 50 ns. We present latest SPHINX experiments and some of the main physic issues of the microsecond regime. Experimental setup and results are described with the aim of giving trends that have been obtained. The main features of microsecond implosion of wire arrays can be analyzed thanks to same methods and theories as used for faster Z-pinches. The effect of load polarity was examined. The stability of the implosion , one of the critical point of microsecond wire arrays due to the load dimensions imposed by the time scale, is tackled. A simple scaling from 100 ns Z-pinch results to 800 ns ones gives good results and the use of nested arrays improves dramatically the implosion quality and the Kshell yield of the load. However, additional effects such as the impact of the return current can geometry on the implosion have to be taken into account on our loads. Axial inhomogeneity of the implosion the origin of which is not yet well understood occurs in some shots and impacts the radiation output. The shape of the radiative pulse is discussed and compared with the homogeneity of the implosion. Numerical 2D R-Z and R-{theta} simulations are used to highlight some experimental results and understand the plasma conditions during these microsecond wire arrays implosions.

  11. Wire Array Z-pinches on Sphinx Machine: Experimental Results and Relevant Points of Microsecond Implosion Physics

    NASA Astrophysics Data System (ADS)

    Calamy, H.; Hamann, F.; Lassalle, F.; Bayol, F.; Mangeant, C.; Morell, A.; Huet, D.; Bedoch, J. P.; Chittenden, J. P.; Lebedev, S. V.; Jennings, C. A.; Bland, S. N.

    2006-01-01

    Centre d'Etudes de Gramat (France) has developed an efficient long implosion time (800 ns) Aluminum plasma radiation source (PRS). Based on the LTD technology, the SPHINX facility is developed as a 1-3MJ, 1μs rise time, 4-10 MA current driver. In this paper, it was used in 1MJ, 4MA configuration to drive Aluminum nested wire arrays Z-pinches with K-shell yield up to 20 kJ and a FWHM of the x-ray pulse of about 50 ns. We present latest SPHINX experiments and some of the main physic issues of the microsecond regime. Experimental setup and results are described with the aim of giving trends that have been obtained. The main features of microsecond implosion of wire arrays can be analyzed thanks to same methods and theories as used for faster Z-pinches. The effect of load polarity was examined. The stability of the implosion , one of the critical point of microsecond wire arrays due to the load dimensions imposed by the time scale, is tackled. A simple scaling from 100 ns Z-pinch results to 800 ns ones gives good results and the use of nested arrays improves dramatically the implosion quality and the Kshell yield of the load. However, additional effects such as the impact of the return current can geometry on the implosion have to be taken into account on our loads. Axial inhomogeneity of the implosion the origin of which is not yet well understood occurs in some shots and impacts the radiation output. The shape of the radiative pulse is discussed and compared with the homogeneity of the implosion. Numerical 2D R-Z and R-θ simulations are used to highlight some experimental results and understand the plasma conditions during these microsecond wire arrays implosions.

  12. Low inductance gas switching.

    SciTech Connect

    Chavez, Ray; Harjes, Henry Charles III; Wallace, Zachariah; Elizondo, Juan E.

    2007-10-01

    The laser trigger switch (LTS) is a key component in ZR-type pulsed power systems. In ZR, the pulse rise time through the LTS is > 200 ns and additional stages of pulse compression are required to achieve the desired <100 ns rise time. The inductance of the LTS ({approx}500nH) in large part determines the energy transfer time through the switch and there is much to be gained in improving system performance and reducing system costs by reducing this inductance. The current path through the cascade section of the ZR LTS is at a diameter of {approx} 6-inches which is certainly not optimal from an inductance point of view. The LTS connects components of much greater diameter (typically 4-5 feet). In this LDRD the viability of switch concepts in which the diameter of cascade section is greatly increased have been investigated. The key technical question to be answered was, will the desired multi-channel behavior be maintained in a cascade section of larger diameter. This LDRD proceeded in 2 distinct phases. The original plan for the LDRD was to develop a promising switch concept and then design, build, and test a moderate scale switch which would demonstrate the key features of the concept. In phase I, a switch concept which meet all electrical design criteria and had a calculated inductance of 150 nH was developed. A 1.5 MV test switch was designed and fabrication was initiated. The LDRD was then redirected due to budgetary concerns. The fabrication of the switch was halted and the focus of the LDRD was shifted to small scale experiments designed to answer the key technical question concerning multi-channel behavior. In phase II, the Multi-channel switch test bed (MCST) was designed and constructed. The purpose of MCST was to provide a versatile, fast turn around facility for the study the multi-channel electrical breakdown behavior of a ZR type cascade switch gap in a parameter space near that of a ZR LTS. Parameter scans on source impedance, gap tilt, gap spacing and

  13. Design and performance of the Z magnetically-insulated transmission lines

    SciTech Connect

    Stygar, W.A.; Spielman, R.B.; Allshouse, G.O.

    1997-08-01

    The 36-module Z accelerator was designed to drive z-pinch loads for weapon-physics and inertial-confinement-fusion experiments, and to serve as a testing facility for pulsed-power research required to develop higher-current drivers. The authors have designed and tested a 10-nH 1.5-m-radius vacuum section for the Z accelerator. The vacuum section consists of four vacuum flares, four conical 1.3-m-radius magnetically-insulated transmission lines, a 7.6-cm-radius 12-post double-post-hole convolute which connects the four outer MITLs in parallel, and a 5-cm-long inner MITL which connects the output of the convolute to a z-pinch load. IVORY and ELECTRO calculations were performed to minimize the inductance of the vacuum flares with the constraint that there be no significant electron emission from the insulator-stack grading rings. Iterative TLCODE calculations were performed to minimize the inductance of the outer MITLs with the constraint that the MITL electron-flow-current fraction be {le} 7% at peak current. The TLCODE simulations assume a 2.5 cm/{micro}s MITL-cathode-plasma expansion velocity. The design limits the electron dose to the outer-MITL anodes to 50 J/g to prevent the formation of an anode plasma. The TLCODE results were confirmed by SCREAMER, TRIFL, TWOQUICK, IVORY, and LASNEX simulations. For the TLCODE, SCREAMER, and TRIFL calculations, the authors assume that after magnetic insulation is established, the electron-flow current launched in the outer MITLs is lost at the convolute. This assumption has been validated by 3-D QUICKSILVER simulations for load impedances {le} 0.36 ohms. LASNEX calculations suggest that ohmic resistance of the pinch and conduction-current-induced energy loss to the MITL electrodes can be neglected in Z power-flow modeling that is accurate to first order. To date, the Z vacuum section has been tested on 100 shots. They have demonstrated they can deliver a 100-ns rise-time 20-MA current pulse to the baseline z-pinch load.

  14. Time and space resolved measurement of the electron temperature, mass density and ionization state in the ablation plasma between two exploding Al wires

    SciTech Connect

    Knapp, P. F.; Pikuz, S. A.; Shelkovenko, T. A.; Hammer, D. A.; Hansen, S. B.

    2012-05-15

    We have determined the properties of plasma around and between two exploding wires using high-resolution x-ray absorption spectroscopy. Plasma densities and temperatures ranging from Greater-Than-Or-Equivalent-To 0.1g/cm{sup 3} and a few eV to less than 0.01 g/cm{sup 3} and 30 eV have been measured in experiments at Cornell University with two 40 {mu}m aluminum (Al) wires spaced 1 mm apart driven by {approx}150 kA peak current pulses with 100 ns rise time. The wire plasma was backlit by the 1.4-1.6 keV continuum radiation produced by a Mo wire X-pinch. The spectrometer employed two spherically bent quartz crystals to record the absorption and backlighter spectra simultaneously. The transition between the dense Al wire core and the coronal plasma is seen as a transition from cold K-edge absorption to Mg-, Na-, and finally Ne-like absorption at the boundary. In the plasma that accumulates between the wires, ionization states up to C-Like Al are observed. The spectrometer geometry and {approx}2{mu}m X-pinch source size provide 0.3 eV spectral resolution and 20 {mu}m spatial resolution enabling us to see 1s{yields} 2p satellite transitions as separate lines as well as O-, F-, and Ne-like 1s{yields} 3p transitions that have not been seen before. A step wedge was used to calibrate the transmission, enabling density to be measured within a factor of two and temperature to be measured within {+-}25%. A genetic algorithm was developed to fit synthetic spectra calculated using the collisional-radiative code SCRAM to the experimental spectra. In order to obtain agreement it was necessary to assume multiple plasma regions with variable thicknesses, thereby allowing the inferred plasma conditions to vary along the absorption path.

  15. PBFA Z: A 50 TW/5 MJ Electrical Generator

    NASA Astrophysics Data System (ADS)

    Spielman, R. B.

    1997-05-01

    PBFA Z is a new 50 TW/5 MJ short electrical driver located at Sandia National Laboratories. We use PBFA Z to magnetically-implode solid or plasma shells. These configurations are historically known as z pinches. The pulsed power design of PBFA Z(R. B. Spielman, et al., Proc. of the Ninth IEEE Pulsed Power Conf., Albuquerque, NM 1995) is based on conventional single-pulse Marx generator, water-line pulse-forming technology used on the earlier Saturn (D. D. Bloomquist, et al., Proc. of the Sixth IEEE Pulsed Power Conf., Arlington, VA edited by P. J. Turchi and B. H. Bernstein (IEEE, New York, 1987), p. 310) and PBFA II(B. N. Turman, et al., Proc. of the Fifth IEEE Pulsed Power Conf., Arlington, VA 1985, pp. 155) accelerators. PBFA Z stores 11.4 MJ in its 36 Marx generators, couples 5 MJ in a 50 TW/100 ns pulse to the output water transmission lines, and delivers 3.4 MJ and 40 TW of electrical energy to the z-pinch load. Depending on the initial load inductance and the implosion time, we attain a peak current of 16-20 MA with a rise time of 105 ns. Current is fed to the z-pinch load through self magnetically-insulated transmission lines (MITLs). Peak electric fields in the MITLs exceed 2 MV /cm. The current from the four independent conical disk MITLs is combined together in a double post-hole vacuum convolute with an efficiency greater than 95%. The measured system performance of the water transmission lines, the vacuum insulator stack, the MITLs, and the double post-hole vacuum convolute differed from preshot predictions by ~ 5%. Using a 2-cm radius and a 2-cm length tungsten wire array with 240, 7.5-=B5m diameter wires (4.1-mg mass) as the z-pinch load, we achieved x-ray powers of 160 TW and x-ray energies of 1.85 MJ as measured by x-ray diodes and resistive bolometry.

  16. Characterisation of the current switch mechanism in two-stage wire array Z-pinches

    SciTech Connect

    Burdiak, G. C.; Lebedev, S. V.; Harvey-Thompson, A. J.; Hall, G. N.; Swadling, G. F.; Suzuki-Vidal, F.; Khoory, E.; Bland, S. N.; Pickworth, L.; Grouchy, P. de; Skidmore, J.; Suttle, L.; Waisman, E. M.

    2015-11-15

    In this paper, we describe the operation of a two-stage wire array z-pinch driven by the 1.4 MA, 240 ns rise-time Magpie pulsed-power device at Imperial College London. In this setup, an inverse wire array acts as a fast current switch, delivering a current pre-pulse into a cylindrical load wire array, before rapidly switching the majority of the generator current into the load after a 100–150 ns dwell time. A detailed analysis of the evolution of the load array during the pre-pulse is presented. Measurements of the load resistivity and energy deposition suggest significant bulk heating of the array mass occurs. The ∼5 kA pre-pulse delivers ∼0.8 J of energy to the load, leaving it in a mixed, predominantly liquid-vapour state. The main current switch occurs as the inverse array begins to explode and plasma expands into the load region. Electrical and imaging diagnostics indicate that the main current switch may evolve in part as a plasma flow switch, driven by the expansion of a magnetic cavity and plasma bubble along the length of the load array. Analysis of implosion trajectories suggests that approximately 1 MA switches into the load in 100 ns, corresponding to a doubling of the generator dI/dt. Potential scaling of the device to higher current machines is discussed.

  17. 3D MHD simulations of radial wire arrays

    NASA Astrophysics Data System (ADS)

    Jennings, C.; Ampleford, D.; Ciardi, A.; Chittenden, J.; Bland, S.; Niasse, N.

    2008-04-01

    We present 3D resistive MHD simulations evaluating multi-MA radial wire arrays as a potential compact, high intensity source for inertial confinement fusion and laboratory astrophysics. A radial wire array consists of wires running radially outwards from a central electrode, and was first investigated at the 1 MA level on the MAGPIE generator at Imperial College. Originally used as a method of producing magnetic tower laboratory jets relevant to astrophysics[1], they have also shown potential as a high power x-ray source. Able to produce x-ray pulses with a rise time and peak power comparable to cylindrical wire arrays, radial arrays occupy a smaller volume and may consequently be able to access higher power densities. We discuss simulation results reproducing radial array experiments performed on the MAGPIE facility as a means of benchmarking our model. This model is then used to evaluate radial wire arrays in the multi-MA regime for planned experiments on the Saturn generator of Sandia National Laboratories. [1] A. Ciardi et al, Phys. Plasmas 14, 056501 (2007)

  18. Nanosecond Pulsed Electric Field Stimulation of Reactive Oxygen Species in Human Pancreatic Cancer Cells is Ca2+-Dependent

    PubMed Central

    Nuccitelli, Richard; Lui, Kaying; Kreis, Mark; Athos, Brian; Nuccitelli, Pamela

    2013-01-01

    The cellular response to 100 ns pulsed electric fields (nsPEF) exposure includes the formation of transient nanopores in the plasma membrane and organelle membranes, an immediate increase in intracellular Ca2+, an increase in reactive oxygen species (ROS), DNA fragmentation and caspase activation. 100 ns, 30 kV/cm nsPEF stimulates an increase in ROS proportional to the pulse number. This increase is inhibited by the anti-oxidant, Trolox, as well as the presence of Ca2+ chelators in the intracellular and extracellular media. This suggests that the nsPEF-triggered Ca2+ increase is required for ROS generation. PMID:23680664

  19. Mega-ampere submicrosecond generator GIT-32

    NASA Astrophysics Data System (ADS)

    Kovalchuk, B. M.; Kharlov, A. V.; Kiselev, V. N.; Kumpyak, E. V.; Zorin, V. B.; Chupin, V. V.; Morozov, A. V.

    2007-03-01

    The GIT-32 current generator was developed for experiments with current carrying pulsed plasma. The main parts of the generator are capacitor bank, multichannel multigap spark switches, low inductive current driving lines, and central load part. The generator consists of four identical sections, connected in parallel to one load. The capacitor bank is assembled from 32 IEK-100-0.17 (0.17μF, 40nH, 100kV) capacitors, connected in parallel. It stores ˜18kJ at 80kV charging voltage. Each two capacitors are commuted to a load by a multigap spark switch with eight parallel channels. Switches operate in ambient air at atmospheric pressure. The GIT-32 generator was tested with 10, 15, and 20nH inductive loads. At 10nH load and 80kV of charging voltage it provides 1MA of current amplitude and 490ns rise time with 0.8Ω damping resistors in discharge circuit of each capacitor and 1.34MA/530ns without resistors. The net generator inductance without a load was optimized to be as low as 12nH, which results in extremely low self-impedance of the generator (˜0.05Ω). It ensures effective energy coupling with low impedance loads like Z pinch. The generator operates reliably without any adjustments in 40-80kV range of charging voltage. Maximum jitter (relative to a triggering pulse) at 40kV charging voltage is about 7ns and lower at higher charging voltages. Operation and handling are very simple, because no oil and no purified gases are required for the generator. The GIT-32 generator has dimensions of 3200×3200×400mm3 and total weight of about 2500kg, thus manifesting itself as a simple, robust, and cost effective apparatus.

  20. Mega-ampere submicrosecond generator GIT-32.

    PubMed

    Kovalchuk, B M; Kharlov, A V; Kiselev, V N; Kumpyak, E V; Zorin, V B; Chupin, V V; Morozov, A V

    2007-03-01

    The GIT-32 current generator was developed for experiments with current carrying pulsed plasma. The main parts of the generator are capacitor bank, multichannel multigap spark switches, low inductive current driving lines, and central load part. The generator consists of four identical sections, connected in parallel to one load. The capacitor bank is assembled from 32 IEK-100-0.17 (0.17 microF, 40 nH, 100 kV) capacitors, connected in parallel. It stores approximately 18 kJ at 80 kV charging voltage. Each two capacitors are commuted to a load by a multigap spark switch with eight parallel channels. Switches operate in ambient air at atmospheric pressure. The GIT-32 generator was tested with 10, 15, and 20 nH inductive loads. At 10 nH load and 80 kV of charging voltage it provides 1 MA of current amplitude and 490 ns rise time with 0.8 Omega damping resistors in discharge circuit of each capacitor and 1.34 MA530 ns without resistors. The net generator inductance without a load was optimized to be as low as 12 nH, which results in extremely low self-impedance of the generator ( approximately 0.05 Omega). It ensures effective energy coupling with low impedance loads like Z pinch. The generator operates reliably without any adjustments in 40-80 kV range of charging voltage. Maximum jitter (relative to a triggering pulse) at 40 kV charging voltage is about 7 ns and lower at higher charging voltages. Operation and handling are very simple, because no oil and no purified gases are required for the generator. The GIT-32 generator has dimensions of 3200 x 3200 x 400 mm(3) and total weight of about 2500 kg, thus manifesting itself as a simple, robust, and cost effective apparatus. PMID:17411179

  1. Mega-ampere submicrosecond generator GIT-32

    SciTech Connect

    Kovalchuk, B. M.; Kharlov, A. V.; Kiselev, V. N.; Kumpyak, E. V.; Zorin, V. B.; Chupin, V. V.; Morozov, A. V.

    2007-03-15

    The GIT-32 current generator was developed for experiments with current carrying pulsed plasma. The main parts of the generator are capacitor bank, multichannel multigap spark switches, low inductive current driving lines, and central load part. The generator consists of four identical sections, connected in parallel to one load. The capacitor bank is assembled from 32 IEK-100-0.17 (0.17 {mu}F, 40 nH, 100 kV) capacitors, connected in parallel. It stores {approx}18 kJ at 80 kV charging voltage. Each two capacitors are commuted to a load by a multigap spark switch with eight parallel channels. Switches operate in ambient air at atmospheric pressure. The GIT-32 generator was tested with 10, 15, and 20 nH inductive loads. At 10 nH load and 80 kV of charging voltage it provides 1 MA of current amplitude and 490 ns rise time with 0.8 {omega} damping resistors in discharge circuit of each capacitor and 1.34 MA/530 ns without resistors. The net generator inductance without a load was optimized to be as low as 12 nH, which results in extremely low self-impedance of the generator ({approx}0.05 {omega}). It ensures effective energy coupling with low impedance loads like Z pinch. The generator operates reliably without any adjustments in 40-80 kV range of charging voltage. Maximum jitter (relative to a triggering pulse) at 40 kV charging voltage is about 7 ns and lower at higher charging voltages. Operation and handling are very simple, because no oil and no purified gases are required for the generator. The GIT-32 generator has dimensions of 3200x3200x400 mm{sup 3} and total weight of about 2500 kg, thus manifesting itself as a simple, robust, and cost effective apparatus.

  2. Stripline magnetic modulators for lasers and accelerators

    SciTech Connect

    Nunnally, W.C.

    1981-01-01

    The basics of magnetic modulators including magnetic element and circuit considerations as applied to accelerators and lasers requiring repetitive (1 to 10 kHz), high voltage (50 to 500 kV), short pulse (50 to 100 ns) are discussed. The scaling of energy losses and switching parameters with material are included.

  3. Plasma Formation and Evolution on Cu, Al, Ti, and Ni Surfaces Driven by a Mega-Ampere Current Pulse

    NASA Astrophysics Data System (ADS)

    Yates, Kevin C.

    Metal alloy mm-diameter rods have been driven by a 1-MA, 100-ns current pulse from the Zebra z-pinch. The intense current produces megagauss surface magnetic fields that diffuse into the load, ohmically heating the metal until plasma forms. Because the radius is much thicker than the skin depth, the magnetic field reaches a much higher value than around a thin-wire load. With the "barbell" load design, plasma formation in the region of interest due to contact arcing or electron avalanche is avoided, allowing for the study of ohmically heated loads. Work presented here will show first evidence of a magnetic field threshold for plasma formation in copper 101, copper 145, titanium, and nickel, and compare with previous work done with aluminum. Copper alloys 101 and 145, titanium grade II, and nickel alloy 200 form plasma when the surface magnetic field reaches 3.5, 3.0, 2.2, and 2.6 megagauss, respectively. Varying the element metal, as well as the alloy, changes multiple physical properties of the load and affects the evolution of the surface material through the multiple phase changes. Similarities and differences between these metals will be presented, giving motivation for continued work with different material loads. During the current rise, the metal is heated to temperatures that cause multiple phase changes. When the surface magnetic field reaches a threshold, the metal ionizes and the plasma becomes pinched against the underlying cooler, dense material. Diagnostics fielded have included visible light radiometry, two-frame shadowgraphy (266 and 532 nm wavelengths), time-gated EUV spectroscopy, single-frame/2ns gated imaging, and multi-frame/4ns gated imaging with an intensified CCD camera (ICCD). Surface temperature, expansion speeds, instability growth, time of plasma formation, and plasma uniformity are determined from the data. The time-period of potential plasma formation is scrutinized to understand if and when plasma forms on the surface of a heated

  4. High-efficiency and compact semiconductor lasers with monolithically integrated switches for generation of high-power nanosecond pulses in time-of-flight (TOF) systems

    NASA Astrophysics Data System (ADS)

    Slipchenko, Sergey; Podoskin, Aleksandr; Soboleva, Olga; Zakharov, Maxim S.; Bakhvalov, Kirill; Romanovich, Dmitrii; Pikhtin, Nikita; Tarasov, Il`ya; Bagaev, Timur; Ladugin, Maxim; Marmalyuk, Aleksandr; Simakov, Vladimir

    2016-03-01

    We present a new approach based on the integration of the functions of a high-efficiency current switch and a laser emitter into a single heterostructure as elements of time-of-flight (TOF) systems. The approach being developed employs the effect of an electrical bistability, which occurs in the general case in thyristor structures. We report recent results obtained in a study of the dynamic electrical and optical characteristics of the pulsed sources we developed. An effective generation of 2- to 100-ns laser pulses at a wavelength of 905 nm is demonstrated. The possibility of generating laser pulses shorter than 1 ns is considered. The maximum peak power reached values of 7 and 50 W for 10- and 100-ns pulses, respectively.

  5. Wavelength dependent delay in the onset of FEL tissue ablation

    SciTech Connect

    Tribble, J.A.; Edwards, G.S.; Lamb, J.A.

    1995-12-31

    We are investigating the wavelength dependence of the onset of laser tissue ablation in the IR Visible and UV ranges. Toward this end, we have made simultaneous measurements of the ejected material (using a HeNe probe beam tangential to the front surface) and the residual stress transient in the tissue (using traditional piezoelectric detection behind the thin samples). For the IR studies we have used the Vanderbilt FEL and for the UV and Vis range we have used a Q-switched ND:Yag with frequency doubling and quadrupling. To satisfy the conditions of the near field limit for the detection of the stress transient, the duration of the IR FEL macropulse must be as short as possible. We have obtained macropulses as short as 100 ns using Pockels Cell technology. The recording of the signals from both the photodiode monitoring the HeNe probe beam and the acoustic detector are synchronized with the arrival of the 100 ns macropulse. With subablative intensities, the resulting stress transient is bipolar with its positive peak separated from its negative peak by 100 ns in agreement with theory. Of particular interest is the comparison of ablative results using 3 {mu}m and 6.45 {mu}m pulses. Both the stress transient and the ejection of material suffer a greater delay (with respect to the arrival of the 100 ns pulse) when the FEL is tuned to 3 {mu}m as compared to 6.45 {mu}m. A comparison of IR Vis and UV data will be discussed in terms of microscopic mechanisms governing the laser ablation process.

  6. Processing time using Datatrieve-11, clunks, and FORTRAN

    SciTech Connect

    Horning, R.R.; Goode, W.E.

    1983-01-01

    Although Datatrieve-11 processes dates with 100-ns resolution using clunks, it has no provision for processing time. This paper describes a set of Datatrieve-11 procedures and FORTRAN-callable subroutines for handling time, as well as dates, expressed in clunks. Although the FORTRAN-callable subroutines use RMS modules, these modules can be extracted from the appropriate RMS library, allowing FORTRAN programs to be linked to an FCS library instead of to RMS.

  7. Two-stage laser-induced synthesis of linear carbon chains

    NASA Astrophysics Data System (ADS)

    Kucherik, A. O.; Arakelian, S. M.; Garnov, S. V.; Kutrovskaya, S. V.; Nogtev, D. S.; Osipov, A. V.; Khor'kov, K. S.

    2016-07-01

    A method is proposed for the synthesis of linear carbon chains under irradiation of colloidal systems consisting of schungite nanoparticles by an ytterbium fibre laser with a pulse duration of 100 ns and an energy up to 1 mJ. Colloidal systems have been previously prepared by laser ablation of a schungite target in distilled water using a Nd3+ : YAG laser with a pulse duration of 1 ms and an energy up to 10 J.

  8. Holmium-doped fibre amplifier operating at 2.1 μm

    SciTech Connect

    Kamynin, V A; Antipov, S O; Kurkov, A S; Baranikov, A V

    2014-02-28

    A small-signal holmium-doped fibre amplifier is demonstrated. The seed source is a cw holmium-doped fibre laser whose output power is modulated by an electro-optical modulator. The maximum gain reached (wavelength, 2.1 μm; power, 0.25 mW; pulse duration, 100 ns; pulse repetition rate, 1 μs) is 28.5 dB. (lasers)

  9. A Current Source Method For t(sub q) Measurement of Fast Switching Thyristors

    NASA Technical Reports Server (NTRS)

    Niedra, Janis M.

    2006-01-01

    A current source driven circuit has been constructed to measure the turn-off time (t(sub q)) of fast-switching SiC thyristors. This circuit operates from a single power supply and a dual channel pulse generator to provide adjustment of forward current, magnitude and duration of reverse applied voltage, and rate of rise of reapplied forward voltage. Values of t(sub q) down to 100 ns can be resolved.

  10. Nonlinear absorption and transmission properties of Ge, Te and InAs using tuneable IR FEL

    SciTech Connect

    Amirmadhi, F.; Becker, K.; Brau, C.A.

    1995-12-31

    Nonlinear absorption properties of Ge, Te and InAs are being investigated using the transmission of FEL optical pulses through these semiconductors (z-scan method). Wavelength, intensity and macropulse dependence are used to differentiate between two-photon and free-carrier absorption properties of these materials. Macropulse dependence is resolved by using a Pockles Cell to chop the 4-{mu}s macropulse down to 100 ns. Results of these experiments will be presented and discussed.

  11. Tungsten quasispherical wire loads with a profiled mass

    SciTech Connect

    Grabovskii, E. V.; Dzhangobegov, V. V. Oleinik, G. M.; Rodionov, R. N.

    2015-12-15

    Wire arrays made from micrometer tungsten wires with linear mass profiled along their height are developed for experiments on the generation of X-ray radiation upon pinch compression with a current of ∼3 MA at a pulse duration of ∼100 ns. Wires are imaged with a scanning electron microscope, and their diameter is determined. It is shown that the arrays have such a profile of height distribution of linear mass that allows for compact spherical compression upon current implosion.

  12. Waveguide Deflector In Lithium Niobate (LiNbO3)

    NASA Astrophysics Data System (ADS)

    Tardieu, A.; Clair, JJ.

    1983-10-01

    We describe the realization of an ultra fast deflector in Ti-diffused LiNbO3 waveguide. We realize practically in 100 ns a linear scanning of an optical beam crossing the component. A driving voltage of 35 volts gives a deflection angle of one degree and the voltage causing deflection to the first spot position (following the Rayleigh resolution criterion) is 10 volts.

  13. Distributed temperature sensing system using a commercial OTDR and a standard EDFA with controlled gain

    NASA Astrophysics Data System (ADS)

    Bassan, Fabio R.; Salgado, Felipe C.; Fruett, Fabiano; Rosolem, Joao B.

    2016-05-01

    The distributed temperature sensor system based in the spontaneous Raman backscattering is demonstrated for the first time to our knowledge, using a commercial OTDR (Optical Time Domain Reflectometer) and a standard erbium doped fiber amplifier (EDFA) with controlled gain. We evaluated this approach in a 30 km of single mode fiber using an OTDR pulse width of 100 ns and an EDFA with 17 dBm of output power.

  14. Heating and ablation of tokamak graphite by pulsed nanosecond Nd-YAG lasers

    SciTech Connect

    Semerok, A.; Fomichev, S. V.; Weulersse, J.-M.; Brygo, F.; Thro, P.-Y.; Grisolia, C.

    2007-04-15

    The results on laser heating and ablation of graphite tiles of thermonuclear tokamaks are presented. Two pulsed Nd-YAG lasers (20 Hz repetition rate, 5 ns pulse duration and 10 kHz repetition rate, 100 ns pulse duration) were applied for ablation measurements. The ablation thresholds (1.0{+-}0.5 J/cm{sup 2} for 5 ns and 2.5{+-}0.5 J/cm{sup 2} for 100 ns laser pulses) were determined for the Tore Supra tokamak graphite tiles (backside) nonexposed to plasma. The high repetition rate Nd-YAG laser (10 kHz, 100 ns pulse duration) and the developed pyrometer system were applied for graphite heating measurements. Some unexpected features of laser heating of the graphite surface were observed. They were explained by the presence of a thin surface layer with the properties different from those of the bulk graphite. The theoretical models of laser heating and near-threshold ablation of graphite with imperfectly adhered layer were developed to interpret the experimental results.

  15. Excimer emission from pulsed microhollow cathode discharges in xenon

    SciTech Connect

    Lee, B.-J.; Nam, S. H.; Rahaman, H.; Iberler, M.; Jacoby, J.; Frank, K.

    2013-12-15

    Direct current (dc) microhollow cathode discharge (MHCD) is an intense source for excimer radiation in vacuum ultraviolet at a wavelength of 172 nm in a high pressure xenon (Xe) gas. The concentration of precursors for the excimer formation, i.e., excited and ionized gas atoms, increases significantly by applying high voltage pulse onto the dc MHCD over the pulse duration range from 20 to 100 ns. The intensity of the excimer emission for the voltage pulse of 20 ns duration exceeds that of the emission intensity obtained from the same MHCD operated only in the dc mode, by one order of magnitude. In addition, the emission intensity increases by one order of magnitude over the pulse duration range from 20 to 100 ns. It can be assumed that the emission intensity of the MHCD source increases as long as the duration of the high voltage pulse is shorter than the electron relaxation time. For the high voltage pulse of 100 ns duration, the emission intensity has been found to be further enhanced by a factor of three when the gas pressure is increased from 200 to 800 mbar.

  16. Excimer emission from pulsed microhollow cathode discharges in xenon

    NASA Astrophysics Data System (ADS)

    Lee, B.-J.; Rahaman, H.; Nam, S. H.; Iberler, M.; Jacoby, J.; Frank, K.

    2013-12-01

    Direct current (dc) microhollow cathode discharge (MHCD) is an intense source for excimer radiation in vacuum ultraviolet at a wavelength of 172 nm in a high pressure xenon (Xe) gas. The concentration of precursors for the excimer formation, i.e., excited and ionized gas atoms, increases significantly by applying high voltage pulse onto the dc MHCD over the pulse duration range from 20 to 100 ns. The intensity of the excimer emission for the voltage pulse of 20 ns duration exceeds that of the emission intensity obtained from the same MHCD operated only in the dc mode, by one order of magnitude. In addition, the emission intensity increases by one order of magnitude over the pulse duration range from 20 to 100 ns. It can be assumed that the emission intensity of the MHCD source increases as long as the duration of the high voltage pulse is shorter than the electron relaxation time. For the high voltage pulse of 100 ns duration, the emission intensity has been found to be further enhanced by a factor of three when the gas pressure is increased from 200 to 800 mbar.

  17. 49 CFR 173.127 - Class 5, Division 5.1-Definition and assignment of packing groups.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Manual of Tests and Criteria, it spontaneously ignites or its mean time for a pressure rise from 690 kPa... cellulose in a 1:1 ratio; or (B) Any material which exhibits a mean pressure rise time less than the pressure rise time of a 1:1 perchloric acid (50 percent)/cellulose mixture. (ii) Packing Group II,...

  18. 49 CFR 173.127 - Class 5, Division 5.1-Definition and assignment of packing groups.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... the UN Manual of Tests and Criteria, it spontaneously ignites or its mean time for a pressure rise... ignites when mixed with cellulose in a 1:1 ratio; or (B) Any material which exhibits a mean pressure rise time less than the pressure rise time of a 1:1 perchloric acid (50 percent)/cellulose mixture....

  19. 49 CFR 173.127 - Class 5, Division 5.1-Definition and assignment of packing groups.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... the UN Manual of Tests and Criteria, it spontaneously ignites or its mean time for a pressure rise... ignites when mixed with cellulose in a 1:1 ratio; or (B) Any material which exhibits a mean pressure rise time less than the pressure rise time of a 1:1 perchloric acid (50 percent)/cellulose mixture....

  20. 49 CFR 173.127 - Class 5, Division 5.1-Definition and assignment of packing groups.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... the UN Manual of Tests and Criteria, it spontaneously ignites or its mean time for a pressure rise... ignites when mixed with cellulose in a 1:1 ratio; or (B) Any material which exhibits a mean pressure rise time less than the pressure rise time of a 1:1 perchloric acid (50 percent)/cellulose mixture....

  1. Model experiment to study sonic boom propagation through turbulence. Part II. Effect of turbulence intensity and propagation distance through turbulence.

    PubMed

    Lipkens, B; Blackstock, D T

    1998-09-01

    A model experiment was reported to be successful in simulating the propagation of sonic booms through a turbulent atmosphere [B. Lipkens and D. T. Blackstock, J. Acoust. Soc. Am. 103, 148-158 (1998)]. In this study the effect on N wave characteristics of turbulence intensity and propagation distance through turbulence are investigated. The main parameters of interest are the rise time and the peak pressure. The effect of turbulence intensity and propagation distance is to flatten the rise time and peak pressure distributions. Rise time and peak pressure distributions always have positive skewness after propagation through turbulence. Average rise time grows with turbulence intensity and propagation distance. The scattering of rise time data is one-sided, i.e., rise times are almost always increased by turbulence. Average peak pressure decreases slowly with turbulence intensity and propagation distance. For the reported data a threefold increase in average rise time is observed and a maximum decrease of about 20% in average peak pressure. Rise times more than ten times that of the no turbulence value are observed. At most, the maximum peak pressure doubles after propagation through turbulence, and the minimum peak pressure values are about one-half the no-turbulence values. Rounded waveforms are always more common than peaked waveforms. PMID:9745733

  2. 76 FR 44829 - Federal Motor Vehicle Safety Standards; Air Brake Systems

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-27

    ... Speed in ft/sec t r = Air pressure rise time in seconds a f = Steady-state deceleration in ft/sec For the final rule, the agency selected an air pressure rise time of 0.45 seconds, which is equal to the... Standards; Air Brake Systems AGENCY: National Highway Traffic Safety Administration (NHTSA), Department...

  3. The First Tests of a Large-Area Light Detector Equipped with Metallic Magnetic Calorimeters for Scintillating Bolometers for the LUMINEU Neutrinoless Double Beta Decay Search

    NASA Astrophysics Data System (ADS)

    Gray, D.; Enss, C.; Fleischmann, A.; Gastaldo, L.; Hassel, C.; Hengstler, D.; Kempf, S.; Loidl, M.; Navick, X. F.; Rodrigues, M.

    2016-08-01

    Future rare-event searches using scintillating crystals need very low background levels for high sensitivity; however, unresolved pile-up can limit this. We present the design and fabrication of large-area photon detectors based on metallic magnetic calorimeters (MMCs), optimized for fast rise times to resolve close pile-up. The first prototypes have been characterized using Fe-55 X-rays and ZnMoO4 crystal scintillation light. A fast intrinsic rise time of 25-30 \\upmu s has been measured and has been compared to the 250 \\upmu s scintillation light pulse rise time constant. The difference indicates that the scintillation process limits the light pulse rise time. The fast rise time allows for a reduction of background due to close pile-up events as well as the study of the inherent crystal scintillation process. MMC-based photon detectors are shown to be a promising tool for scintillating crystal based rare event searches.

  4. Experimental investigation of vibration-induced bulk solids transport and segregation. Quarterly report ending March 31, 1996

    SciTech Connect

    Rosato, A.D.; Dave, R.N.

    1996-09-01

    An experimental investigation of the motion of a single large sphere in a bed of dry granular material subjected to vertical vibration is presented. We have studied the rise time of the sphere as a function of vibration parameters, frequency and amplitude. While previous results report a decreasing rise time with increasing relative acceleration, we evidence the existence of a critical frequency where the rise time jumps to greater values before decreasing again. We also show that the rise time scales with the velocity amplitude of vibration and the transition corresponds approximately to a doubling of rise time. The results reported are over a rather narrow range of input accelerations, and generally involve gross phenomena of heaping and fluidization. Observations of the dynamic trajectory of the rising particle are also reported through the use of a novel non-intrusive particle tracking system. 16 refs., 7 figs.

  5. Pulsed corona discharge: the role of ozone and hydroxyl radical in aqueous pollutants oxidation.

    PubMed

    Preis, S; Panorel, I C; Kornev, I; Hatakka, H; Kallas, J

    2013-01-01

    Ozone and hydroxyl radical are the most active oxidizing species in water treated with gas-phase pulsed corona discharge (PCD). The ratio of the species dependent on the gas phase composition and treated water contact surface was the objective for the experimental research undertaken for aqueous phenol (fast reaction) and oxalic acid (slow reaction) solutions. The experiments were carried out in the reactor, where aqueous solutions showered between electrodes were treated with 100-ns pulses of 20 kV voltage and 400 A current amplitude. The role of ozone increased with increasing oxygen concentration and the oxidation reaction rate. The PCD treatment showed energy efficiency surpassing that of conventional ozonation.

  6. A composition analyzer for microparticles using a spark ion source. [using time of flight spectrometers

    NASA Technical Reports Server (NTRS)

    Auer, S. O.; Berg, O. E.

    1975-01-01

    Iron microparticles were fired onto a capacitor-type microparticle detector which responded to an impact with a spark discharge. Ion currents were extracted from the spark and analyzed in a time-of-flight mass spectrometer. The mass spectra showed the element of both detector and particle materials. The total extracted ion currents was typically 10A within a period of 100ns, indicating very efficient vaporization of the particle and ionization of the vapor. Potential applications include research on cosmic dust, atmospheric aerosols and cloud droplets, particles ejected by rocket or jet engines, by machining processes, or by nuclear bomb explosions.

  7. Investigation of cosmic rays in very short time scales

    NASA Technical Reports Server (NTRS)

    Peltonen, J.; Valtonen, E.; Torsti, J. J.; Arvela, H.; Lumme, M.; Nieminen, M.; Vainikka, E.

    1985-01-01

    A fast databuffer system, where cosmic ray events in the Turku hadron spectrometer, including particle arrival times are recorded with time resolution of 100 ns was constructed. The databuffer can be read continuously by a microprocessor, which preanalyzes the data and transfers it to the main computer. The time span, that can be analyzed in every detail, is a few seconds. The high time resolution enables a study of time correlated groups of high energy particles. In addition the operational characteristics of the spectrometer can be monitored in detail.

  8. rf-microwave switches based on reversible semiconductor-metal transition of VO2 thin films synthesized by pulsed-laser deposition

    NASA Astrophysics Data System (ADS)

    Dumas-Bouchiat, F.; Champeaux, C.; Catherinot, A.; Crunteanu, A.; Blondy, P.

    2007-11-01

    Microwave switching devices based on the semiconductor-metal transition of VO2 thin films were developped on two types of substrates (C-plane sapphire and SiO2/Si), and in both shunt and series configurations. Under thermal activation, the switches achieved up to 30-40dB average isolation of the radio-frequency (rf) signal on 500MHz -35GHz frequency band with weak insertion losses. These VO2-based switches can be electrically activated with commutation times less than 100ns, which make them promising candidates for realizing efficient and simple rf switches.

  9. Widely tunable gas laser for remote sensing

    NASA Technical Reports Server (NTRS)

    Rothe, D. E.

    1988-01-01

    An advanced, highly efficient and reliable Rare-Gas Halide laser was developed. It employs the following: (1) novel prepulse techniques and impedance matching for efficient energy transfer; (2) magnetic switches for high reliability; (3) x-ray preionization for discharge uniformity and beam quality; and (4) an integrated gas flow loop for compactness. When operated as a XeCl laser, the unit produces 2 J per pulse with good beam uniformity. Optical pulse duration is 100 ns. Pulse repetition rate was tested up to 25 Hz. Efficiency is 3 percent.

  10. Ultrasound propagation measurements and applications

    NASA Technical Reports Server (NTRS)

    Lynnworth, L. C.; Papadakis, E. P.; Fowler, K. A.

    1977-01-01

    This paper reviews three systems designed for accurately measuring the propagation of ultrasonic pulses. The three systems are presented in order of velocity-measuring precision: + or - 100 ns, + or - 1 ns, + or - 0.2 ns. Also included is a brief discussion of phase and group velocities, with reference to dispersive, highly attenuating materials. Measurement of attenuation by pulse-echo buffer rod techniques is described briefly. These techniques and instruments have been used to measure sound velocity and attenuation in a variety of materials and shapes, over a wide temperature range.

  11. High power testing of a 17 GHz photocathode RF gun

    SciTech Connect

    Chen, S.C.; Danly, B.G.; Gonichon, J.

    1995-12-31

    The physics and technological issues involved in high gradient particle acceleration at high microwave (RF) frequencies are under study at MIT. The 17 GHz photocathode RF gun has a 1 1/2 cell ({pi} mode) room temperature cooper cavity. High power tests have been conducted at 5-10 MW levels with 100 ns pulses. A maximum surface electric field of 250 MV/m was achieved. This corresponds to an average on-axis gradient of 150 MeV/m. The gradient was also verified by a preliminary electron beam energy measurement. Even high gradients are expected in our next cavity design.

  12. Prospects for x-ray polarimetry measurements of magnetic fields in magnetized liner inertial fusion plasmas

    SciTech Connect

    Lynn, Alan G. Gilmore, Mark

    2014-11-15

    Magnetized Liner Inertial Fusion (MagLIF) experiments, where a metal liner is imploded to compress a magnetized seed plasma may generate peak magnetic fields ∼10{sup 4} T (100 Megagauss) over small volumes (∼10{sup −10}m{sup 3}) at high plasma densities (∼10{sup 28}m{sup −3}) on 100 ns time scales. Such conditions are extremely challenging to diagnose. We discuss the possibility of, and issues involved in, using polarimetry techniques at x-ray wavelengths to measure magnetic fields under these extreme conditions.

  13. Speckle spectroscopy; an application for the multi-anode microchannel array detector system

    NASA Technical Reports Server (NTRS)

    Butcher, H. R.; Joseph, C. L.; Timothy, J. G.

    1982-01-01

    Plans to combine the High Angular Resolution Imager/Spectrometer on the 4-meter Mayall telescope at the Kitt Peak National Observatory and the (256 x 1024)-pixel Multi-Anode Microchannel Array detector system to produce a unique instrument for speckle spectroscopy are described. The pulse-counting detector system will provide distortion-free imaging and will time tag each spatially-resolved photon event with an accuracy of 100 ns. The Imager/Spectrometer will provide a spatial resolution of 0.07 arcsec orthogonal to the plane of dispersion and 0.18 arcsec in the plane of dispersion.

  14. TEMPO machine

    SciTech Connect

    Rohwein, G.J.; Lancaster, K.T.; Lawson, R.N.

    1986-06-01

    TEMPO is a transformer powered megavolt pulse generator with an output pulse of 100 ns duration. The machine was designed for burst mode operation at pulse repetition rates up to 10 Hz with minimum pulse-to-pulse voltage variations. To meet the requirement for pulse duration a nd a 20-..omega.. output impedance within reasonable size constraints, the pulse forming transmission line was designed as two parallel water-insulated, strip-type Blumleins. Stray capacitance and electric fields along the edges of the line elements were controlled by lining the tank with plastic sheet.

  15. Inactivation of a 25.5 µm Enterococcus faecalis biofilm by a room-temperature, battery-operated, handheld air plasma jet

    NASA Astrophysics Data System (ADS)

    Pei, X.; Lu, X.; Liu, J.; Liu, D.; Yang, Y.; Ostrikov, K.; Chu, Paul K.; Pan, Y.

    2012-04-01

    Effective biofilm inactivation using a handheld, mobile plasma jet powered by a 12 V dc battery and operated in open air without any external gas supply is reported. This cold, room-temperature plasma is produced in self-repetitive nanosecond discharges with current pulses of ˜100 ns duration, current peak amplitude of ˜6 mA and repetition rate of ˜20 kHz. It is shown that the reactive plasma species penetrate to the bottom layer of a 25.5 µm-thick Enterococcus faecalis biofilm and produce a strong bactericidal effect. This is the thickest reported biofilm inactivated using room-temperature air plasmas.

  16. Increasing the electric strength of vacuum insulation by treating the electrodes with a low-energy, high-current electron beam

    SciTech Connect

    Batrakov, A.V.; Nazarov, D.S.; Ozur, G.E.

    1996-12-31

    The paper is devoted to the study of how the irradiation of the electrode surface with a low-energy, high-current electron beam affects the prebreakdown current and the electric strength of the vacuum insulation. This study is an extension of the work whose results were presented at the XVI ISDEIV. Experiments have been performed for 0.1-mm vacuum gaps formed by refractory-metal electrodes and for millimeter vacuum gaps with a pulsed voltage of amplitude 250 kV and duration 30-100 ns.

  17. Modeling charge relaxation in graphene quantum dots induced by electron-phonon interaction

    NASA Astrophysics Data System (ADS)

    Reichardt, Sven; Stampfer, Christoph

    2016-06-01

    We study and compare two analytic models of graphene quantum dots for calculating charge relaxation times due to electron-phonon interaction. Recently, charge relaxation processes in graphene quantum dots have been probed experimentally and here we provide a theoretical estimate of relaxation times. By comparing a model with pure edge confinement to a model with electrostatic confinement, we find that the latter features much larger relaxation times. Interestingly, relaxation times in electrostatically defined quantum dots are predicted to exceed the experimentally observed lower bound of ˜100 ns.

  18. The study of neutron burst shape of a neutron tube driven by dispenser cathode

    NASA Astrophysics Data System (ADS)

    Grishnyaev, Evgeny; Polosatkin, Sergey

    2016-08-01

    A slim-shaped portable DD-neutron generator is developed at Budker institute of Nuclear Physics. The generator is a combination of Cockcroft-Walton voltage multiplier and a sealed gas-filled neutron tube driven by dispenser cathode. Neutron burst shape in pulsed mode of neutron tube operation is measured with stroboscopic time spectrometry, implemented on scintillation detector, and modeled with Comsol Script 1.3 and Comsol Multiphysics 3.5. Modeling appears to be in good agreement with experimental results. Measured pulse rise and fall times are 110 ns and 100 ns respectively.

  19. Effect of Alcohol on Interaction of Model Biological Membrane with Steroids

    NASA Astrophysics Data System (ADS)

    Pinna, Marco; Mura, Manuela; Famili, Marjan; Zhou, Yuhua; Zvelindovsky, Andrei

    2014-03-01

    The effect of alcohol in the lipid bilayer changes the gel-phase structure of the lipid bilayer. Interactions between the alcohol molecules and the lipid bilayer were investigated using molecular dynamics. Alcohols such as ethanol and methanol are often used in drug delivery application. Ethanol is used to dissolve hydrophobic steroidal drugs such as Beclamethasone dipropionate, Fluticasone propionate and Prednisone. All the systems considered were equilibrated at 310K and ran for 100ns in the presence of dimyristoylphosphatidylcholine (DMPC) lipid bilayer. In addition the simulations were performed to investigate the behaviour of anti-asthma drugs such as Beclamethasone dipropionate in the water environment and 2.5% of ethanol.

  20. Accumulated destructive effect of nanosecond repetitive voltage pulses on the insulated coatings of Fe-based nanocrystalline ribbon

    SciTech Connect

    Zhang, Yu; Liu, Jinliang

    2013-03-11

    Fe-based nanocrystalline ribbon is widely employed in pulsed power devices and accelerators. A temperature accumulation model is put forward to explain the accumulated destructive effect of discharge plasma bombardment on the TiO{sub 2} coatings of nanocrystalline ribbon under 50 Hz/100 ns voltage pulses. Experimental results revealed that the plasma channel expansion caused by air breakdown in the coating crack heated the coating repetitively, and the coating temperature was increased and accumulated around the crack. The fact that repetitive voltage pulses were more destructive than a single pulse with the same amplitude was caused by the intensified coating ablation under the temperature accumulation effect.

  1. Can I Donate My Organs If I've Had Cancer?

    MedlinePlus

    ... To learn more National organizations and websites* United Network for Organ Sharing (UNOS) Toll-free number: 1- ... MA, Delmonici FL. First report of the United Network for Organ Sharing Transplant Tumor Registry: Donors with ...

  2. Subjective loudness of N-wave sonic booms.

    PubMed

    Niedzwiecki, A; Ribner, H S

    1978-12-01

    A loudspeaker-driven simulation booth with extended rise-time capability (down to 0.22 ms) has been used for subjective loudness tests of N-wave sonic booms. The test series compared signatures over a range of 0.22--10 ms in rise time, 100--250 ms in duration and 0.5--2.5 psf (24--120 Pa) in peak overpressure. In one sequence, the tradeoff between rise time and overpressure was measured for equal loudness; in another, the tradeoff between duration and overpressure. For equal loudness 10-ms rise time required 8-dB higher overpressure than for 1-ms rise time. Duration had little effect in the range 100--200 ms, but at 250 ms noticeably enhanced the loudness. These results confirm those measured by Shepherd and Sutherland made at 1-ms rise time and above (except for the anomalous enhancement at 250-ms duration), and extend the measurements down to 0.22 ms. There is also good agreement with theoretical predictions (Johnson-Robinson, Zepler-Harel methods) except for the 10-ms rise time and 250-ms duration cases. PMID:739096

  3. The relationship between beliefs about sleep and adherence to behavioral treatment combined with meditation for insomnia.

    PubMed

    Cvengros, Jamie A; Crawford, Megan R; Manber, Rachel; Ong, Jason C

    2015-01-01

    This study examined beliefs about sleep, as measured by the Dysfunctional Beliefs and Attitudes about Sleep (DBAS) scale, as predictors of adherence to 3 specific insomnia treatment recommendations: restriction of time spent in bed, maintenance of a consistent rise time, and completion of daily meditation practice. Higher DBAS scores predicted poorer adherence to restriction of time spent in bed and to maintenance of a prescribed rise time. DBAS scores were not associated with completion of daily meditation. These preliminary findings suggest that pre-treatment beliefs about sleep may impact patient engagement with behavioral recommendations regarding time in bed and consistent rise time during treatment for insomnia.

  4. Optimal space communications techniques. [discussion of video signals and delta modulation

    NASA Technical Reports Server (NTRS)

    Schilling, D. L.

    1974-01-01

    The encoding of video signals using the Song Adaptive Delta Modulator (Song ADM) is discussed. The video signals are characterized as a sequence of pulses having arbitrary height and width. Although the ADM is suited to tracking signals having fast rise times, it was found that the DM algorithm (which permits an exponential rise for estimating an input step) results in a large overshoot and an underdamped response to the step. An overshoot suppression algorithm which significantly reduces the ringing while not affecting the rise time is presented along with formuli for the rise time and the settling time. Channel errors and their effect on the DM encoded bit stream were investigated.

  5. Investigation of the phase stability of an X-band long pulse multibeam relativistic klystron amplifier

    NASA Astrophysics Data System (ADS)

    Liu, Zhenbang; Huang, Hua; Jin, Xiao; Lei, Lurong; Zhu, Lei; Li, Lele; Li, Shifeng; Yan, Wenkang; He, Hu

    2016-09-01

    To realize coherent high power microwave combining, an X-band long pulse multibeam relativistic klystron amplifier is designed, and the relative phase stability is investigated by three dimensions particle in cell simulation and high power microwave experiment. The simulation shows that the relative phase difference can be stabilized at gigawatt level radiation power. But the relative phase jitter increases in the experiment, then some measures are proposed to improve the stability of relative phase difference and avoid pulse shortening. A 0.98 GW radiation power with pulse duration of 160 ns is obtained in the experiment, the pulse shortening is avoided. The relative phase difference fluctuation between output microwave and input RF signal is less than ±25° in a single shot with duration of 100 ns. Then, the experiment of pulse repetition is carried out, and an output microwave with 0.98 GW radiation power at 25 Hz repetition rate is obtained. The power conversion efficiency is about 35% with pulse duration of 160 ns. The relative phase difference is less than ±30° at 25 Hz repetition rate in 100 ns.

  6. Experimental Investigation of Axial and Beam-Riding Propulsive Physics with TEA CO2 laser

    NASA Astrophysics Data System (ADS)

    Kenoyer, D. A.; Salvador, I.; Myrabo, L. N.; Notaro, S. N.; Bragulla, P. W.

    2010-10-01

    A twin Lumonics K922M pulsed TEA CO2 laser system (pulse duration of approximately 100 ns FWHM spike, with optional 1 μs tail, depending upon laser gas mix) was employed to experimentally measure both axial thrust and beam-riding behavior of Type ♯200 lightcraft engines, using a ballistic pendulum and Angular Impulse Measurement Device (AIMD, respectively. Beam-riding forces and moments were examined along with engine thrust-vectoring behavior, as a function of: a) laser beam lateral offset from the vehicle axis of symmetry; b) laser pulse energy (˜12 to 40 joules); c) pulse duration (100 ns, and 1 μs); and d) engine size (97.7 mm to 161.2 mm). Maximum lateral momentum coupling coefficients (CM) of 75 N-s/MJ were achieved with the K922M laser whereas previous PLVTS laser (420 J, 18 μs duration) results reached only 15 N-s/MJ—an improvement of 5x. Maximum axial CM performance with the K922M reached 225 N-s/MJ, or about ˜3x larger than the lateral CM values. These axial CM results are sharply higher than the 120 N/MW previously reported for long pulse (e.g., 10-18 μs) CO2 electric discharge lasers.

  7. Intrapulse temporal and wavelength shifts of a high-power 2.1-µm Ho:YAG laser and their potential influence on atmospheric lidar measurements.

    PubMed

    Vaidyanathan, M; Killinger, D K

    1994-11-20

    A high-power, flash-lamp-pumped, Q-switched Ho:YAG laser has been developed to produce up to 150 mJ in a 100-ns Q-switched pulse. The Ho laser was initially used in a direct detection lidar-differential absorption lidar (DIAL) system to measure vertical density profiles of aerosols and water vapor in the atmosphere. It was found, however, that the Ho laser operated simultaneously on two closely spaced spectral emission wavelengths (2.090 and 2.097 µm) and that the distribution of energy between the two wavelengths could change significantly on time scales of several seconds to minutes. Such intrapulse temporal and wavelength shifts were found to alter the atmospheric lidar return significantly because one of the laser lines coincided with a water vapor absorption line in the atmosphere. This laser spectral output problem was overcome by the use of intracavity étalons that controlled the laser spectral-temporal characteristics but reduced the laser output energy to approximately 75 mJ/pulse in a 100-ns pulse length. These results are important as they serve to point out the difficulties of developing and using a high-power 2.1- µm Ho laser for atmospheric lidar when high-resolution spectral and temporal characteristics can significantly influence the lidar return and be misinterpreted as resulting from atmospheric signals.

  8. Simulation study on nitrogen vibrational kinetics in a single nanosecond pulse high voltage air discharge

    NASA Astrophysics Data System (ADS)

    Yang, Wei; Zhou, Qianhong; Dong, Zhiwei

    2016-05-01

    We report a simulation study on nitrogen vibrational kinetics N 2 ( X 1 Σg + , v = 0 - 12 ) in a single nanosecond pulse high voltage discharge in dry-air at a pressure of 100 Torr. Apart from the usual processes such as vibrational-vibrational exchange and vibrational-translational relaxation, the state-specific vibrational kinetics take into account the electronic-vibrational (E-V) process and chemical-vibrational process. The vibrational kinetics, coupled with electron Boltzmann equation solver, plasma chemical kinetics, and gas thermal balance are used to model the 100 ns discharge and its subsequent 10 ms afterglow. The self-consistent model shows good agreement with recent experimental results, with regard to time-resolved vibrational and translational temperature. According to the modeling results, The E-V mechanism has a small but non-negligible effect (about 2%) in rising of vibrational quanta in the early afterglow from 100 ns to 1μs. Another possible reason is the convective transport associated with the gas dynamic expansion in time delays around 1μs to 10 μs.

  9. A modified infrared spectrometer with high time resolution and its application for investigating fast conformational changes of the GTPase Ras.

    PubMed

    Lin, Jie; Gerwert, Klaus; Kötting, Carsten

    2014-01-01

    Time-resolved infrared spectroscopy is a valuable tool for the investigation of proteins and protein interactions. The investigation of many biological processes is possible by means of caged compounds, which set free biologically active substances upon light activation. Some caged compounds could provide sub-nanosecond time resolution, e.g., para-hydroxyphenacyl-guanosine 5'-triphosphate (GTP) forms GTP in picoseconds. However, the time resolution in single shot experiments with rapid-scan Fourier transform infrared (FT-IR) spectrometers is limited to about 10 ms. Here we use an infrared diode laser instead of the conventional globar and achieve a time resolution of 100 ns. This allows for the time-resolved measurement of the fast Ras(off) to Ras(on) conformational change at room temperature. We quantified the activation parameters for this reaction and found that the free energy of activation for this reaction is mainly enthalpic. Investigation of the same reaction in the presence of the Ras binding domain of the effector Raf (RafRBD) reveals a four orders of magnitude faster reaction, indicating that Ras·RafRBD complex formation directly induces the conformational change. Recent developments of broadly tunable quantum cascade lasers will further improve time resolution and usability of the setup. The reported 100 ns time resolution is the best achieved for a non-repetitive experiment so far.

  10. An improved microfluidics approach for monitoring real-time interaction profiles of ultrafast molecular recognition

    NASA Astrophysics Data System (ADS)

    Batabyal, Subrata; Rakshit, Surajit; Kar, Shantimoy; Pal, Samir Kumar

    2012-04-01

    Our study illustrates the development of a microfluidics (MF) platform combining fluorescence microscopy and femtosecond/picosecond-resolved spectroscopy to investigate ultrafast chemical processes in liquid-phase diffusion-controlled reactions. By controlling the flow rates of two reactants in a specially designed MF chip, sub-100 ns time resolution for the exploration of chemical intermediates of the reaction in the MF channel has been achieved. Our system clearly rules out the possibility of formation of any intermediate reaction product in a so-called fast ionic reaction between sodium hydroxide and phenolphthalein, and reveals a microsecond time scale associated with the formation of the reaction product. We have also used the developed system for the investigation of intermediate states in the molecular recognition of various macromolecular self-assemblies (micelles) and genomic DNA by small organic ligands (Hoechst 33258 and ethidium bromide). We propose our MF-based system to be an alternative to the existing millisecond-resolved "stopped-flow" technique for a broad range of time-resolved (sub-100 ns to minutes) experiments on complex chemical/biological systems.

  11. Laser propulsion experiments in South Africa

    NASA Astrophysics Data System (ADS)

    Michaelis, Max M.; Moorgawa, Ashokabose; Forbes, Andrew; Klopper, Wouter; McKenzie, Edric; Boutchiama, David; Bencherif, Hassan

    2002-09-01

    Two sets of experiments indicate a renewal of interest in South Africa in the topic of laser propulsion. Both sets were conducted under the auspices of the new National Laser Center. In the first set, a 1 kW, CO2 laser (1 kHz, 1 J, 100 ns) was used to propel small (ca 1 gram) targets through a vertical tube-launcher and the momentum-coupling coefficient for a variety of conditions was estimated. The somewhat disappointing results were accounted for in terms of the poor beam quality from a single oscillator and premature break-down of the exhaust vapor in the tube. These experiments were conducted with one module of the now dismantled 'MLIS' uranium isotope separation system. The second set of experiments being conducted in Durban with a small but more energetic 'marking' laser (CO2 20 Hz., 4 J, 100 ns). The chief purpose of this, was to better understand the discrepancies between the recent vertical propulsion experiment at Pelindaba and earlier propulsion attempts with the original MLIS chain. Preliminary pendulum experiments were carried out. Burning targets exhibited enhanced coupling for single pulses.

  12. Experimental Investigation of Axial and Beam-Riding Propulsive Physics with TEA CO{sub 2} laser

    SciTech Connect

    Kenoyer, D. A.; Salvador, I.; Myrabo, L. N.; Notaro, S. N.; Bragulla, P. W.

    2010-10-08

    A twin Lumonics K922M pulsed TEA CO{sub 2} laser system (pulse duration of approximately 100 ns FWHM spike, with optional 1 {mu}s tail, depending upon laser gas mix) was employed to experimentally measure both axial thrust and beam-riding behavior of Type no. 200 lightcraft engines, using a ballistic pendulum and Angular Impulse Measurement Device (AIMD, respectively. Beam-riding forces and moments were examined along with engine thrust-vectoring behavior, as a function of: a) laser beam lateral offset from the vehicle axis of symmetry; b) laser pulse energy ({approx}12 to 40 joules); c) pulse duration (100 ns, and 1 {mu}s); and d) engine size (97.7 mm to 161.2 mm). Maximum lateral momentum coupling coefficients (C{sub M}) of 75 N-s/MJ were achieved with the K922M laser whereas previous PLVTS laser (420 J, 18 {mu}s duration) results reached only 15 N-s/MJ--an improvement of 5x. Maximum axial C{sub M} performance with the K922M reached 225 N-s/MJ, or about {approx}3x larger than the lateral C{sub M} values. These axial C{sub M} results are sharply higher than the 120 N/MW previously reported for long pulse (e.g., 10-18 {mu}s)CO{sub 2} electric discharge lasers.

  13. Recent developments in superconducting cavity RF control

    NASA Astrophysics Data System (ADS)

    Simrock, Stefan

    2005-02-01

    Presently a large number of superconducting accelerators under construction or proposed impose stringent requirements on the rf control of the accelerating fields, operability, and reliability. The accelerator application range from linear colliders, UV-FELs and X-FELs, ERL based light sources, high power proton accelerators to heavy ion accelerators. Examples are TESLA and NLC, the European XFEL and Lux, the Cornell ERL based light source, the high power ERL based IR-FEL at JLAB, the neutron spallation source SNS, the heavy ion accelerator RIA, and the energy upgrade of the CEBAF accelerator at JLAB. The requirements on the rf systems range from low to high current, medium to high gradient, and relativistic to non-relativistics beam. With the technology in analog and digital electronics developing rapidly, the technology for rf feedback system is changing more and more from analog or hybrid systems towards fully digital systems. Todays DSPs and FPGAs can process sophisticated feedback algorithms on a time scale of some 100 ns to a few us with ADCs and DACs with about 100 MHz bandwidth at 14 bit and latencies less than 100 ns available to inter-face to the field detectors and field control actuators. Also fast analog multiplier technology allows for field detection and actuators for rf control with high linearity, measurement and control bandwidth while maintaining low noise levels.

  14. Emission properties of explosive field emission cathodes

    SciTech Connect

    Roy, Amitava; Patel, Ankur; Menon, Rakhee; Sharma, Archana; Chakravarthy, D. P.; Patil, D. S.

    2011-10-15

    The research results of the explosive field emission cathode plasma expansion velocity and the initial emission area in the planar diode configuration with cathodes made of graphite, stainless steel, polymer velvet, carbon coated, and carbon fiber (needle type) cathodes are presented. The experiments have been performed at the electron accelerator LIA-200 (200 kV, 100 ns, and 4 kA). The diode voltage has been varied from 28-225 kV, whereas the current density has been varied from 86-928 A/cm{sup 2} with 100 ns pulse duration. The experimentally obtained electron beam diode perveance has been compared with the 1 dimensional Child-Langmuir- law. It was found that initially only a part of the cathode take part in the emission process. The plasma expands at 1.7-5.2 cm/{mu}s for 4 mm anode-cathode gap for various cathode materials. It was found that the plasma expansion velocity increases with the decrease in the cathode diameter. At the beginning of the accelerating pulse, the entire cathode area participates in the electron emission process only for the multiple needle type carbon fiber cathode.

  15. Signal processing for semiconductor detectors

    SciTech Connect

    Goulding, F.S.; Landis, D.A.

    1982-02-01

    A balanced perspective is provided on the processing of signals produced by semiconductor detectors. The general problems of pulse shaping to optimize resolution with constraints imposed by noise, counting rate and rise time fluctuations are discussed.

  16. A development of X-ray polarimeter using microstrip gas proportional counter

    SciTech Connect

    Sugeno, H.; Takamura, Y.; Sakurai, H.

    1996-12-31

    An application of a microstrip gas proportional counter to a X-ray polarimeter was investigated. Primary electron clouds produced by photoelectric absorption extend to the direction of the electric vector of incident polarized X-rays. Then the length of the electron clouds projected to the microstrip plate (MS plate) affects to the rise time of signal from Microstrip Gas Proportional Counter (MSGC). By a prototype counter mounting a MS plate, the characteristics of the rise time distributions of the pulse from MSGC were investigated as a function of the pressure, the energy, the gas gain, and the reduced field. When the prototype counter was irradiated with polarized X-rays which have parallel or perpendicular electric vector to MS plate, the difference of 24ns between the peak channels of the rise time distributions was observed for two cases. The results indicate that the detection of the rise time could be used as a X-ray polarimeter technique.

  17. Study of temporal pulse shape effects on W using simulations and laser heating

    NASA Astrophysics Data System (ADS)

    Yu, J. H.; De Temmerman, G.; Doerner, R. P.; van den Berg, M. A.

    2016-02-01

    Transient heat pulses with triangular, square, and ELM-like temporal shapes are investigated in order to further understand how transient plasma instabilities will affect plasma facing components in tokamaks. A solution to the 1D heat equation for triangular pulses allows the peak surface temperature to be written analytically for arbitrary rise times. The solution as well as ANSYS simulations reveal that a positive ramp (maximum rise time) triangular pulse has a higher peak surface temperature by a factor of \\sqrt{2} compared to that from a negative ramp (rise time = 0) pulse shape with equal energy density, peak power, and pulse width. Translating the results to ITER, an ELM or disruption pulse with the shortest rise time is the most benign compared to other pulse shapes with the same peak heat flux and same energy density.

  18. Granular size separation investigated by MRI: The role of air-granule interactions

    NASA Astrophysics Data System (ADS)

    Möbius, Matthias E.; Karczmar, Gregory S.; Nagel, Sidney R.; Jaeger, Heinrich M.

    2003-03-01

    Recent experiments have shown the importance of air in the process of size separation in granular materials. We study the air-granular dynamics in the context of an effective permeability of the granular medium. This gives rise to intruder density dependent rise times which can be categorized into three different regimes: For highly permeable media the rise time is density independent, intermediate permeabilities show a non-monotonic rise time vs. density curve. The rise time vs. density is monotonic for poorly permeable media. These media can also exhibit the so called reverse brazil nut effect for low density intruders. We investigate the dynamics of these systems with MRI and high-speed video.

  19. Intra-beam scattering

    NASA Astrophysics Data System (ADS)

    Piwinski, A.

    Intra-beam scattering is analysed and the rise times or damping times of the beam dimensions are derived. The theoretical results are compared with experimental values obtained on the CERN AA and SPS machines.

  20. Effects of discharge voltage waveform on the discharge characteristics in a helium atmospheric plasma jet

    SciTech Connect

    Uchida, Giichiro Takenaka, Kosuke; Setsuhara, Yuichi

    2015-04-21

    We present here an analysis of the discharge characteristics of a He plasma jet operating under three different types of applied voltage waveform: (a) a μs-pulse voltage waveform with a slow voltage rise time, (b) ns-pulse, and (c) rectangular voltage waveforms with fast voltage rise time. Optical emission measurements show that the application of a voltage with a fast voltage rise time induces rapid discharge growth and, consequently, produces an abundance of energetic electrons, which in turn leads to high optical emission from the O atoms. We also estimate the optical emission efficiency of the O atom (η{sub o}), which corresponds roughly to the production efficiency of the reactive O species. η{sub o} increases with increasing applied voltage, and the highest value of η{sub o} is obtained in the shortest pulse discharge, which was ignited by a ns-pulse voltage waveform with a fast voltage rise time and short pulse width.

  1. 47 CFR 90.351 - Location and Monitoring Service.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...) For codes and timing scheme: A table of bit sequences and their alphanumeric or indicator equivalents, and a statement of bit rise time, bit transmission rates, bit duration, and interval between bits;...

  2. 47 CFR 90.351 - Location and Monitoring Service.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...) For codes and timing scheme: A table of bit sequences and their alphanumeric or indicator equivalents, and a statement of bit rise time, bit transmission rates, bit duration, and interval between bits;...

  3. 47 CFR 90.351 - Location and Monitoring Service.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...) For codes and timing scheme: A table of bit sequences and their alphanumeric or indicator equivalents, and a statement of bit rise time, bit transmission rates, bit duration, and interval between bits;...

  4. 47 CFR 90.351 - Location and Monitoring Service.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...) For codes and timing scheme: A table of bit sequences and their alphanumeric or indicator equivalents, and a statement of bit rise time, bit transmission rates, bit duration, and interval between bits;...

  5. 47 CFR 90.351 - Location and Monitoring Service.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...) For codes and timing scheme: A table of bit sequences and their alphanumeric or indicator equivalents, and a statement of bit rise time, bit transmission rates, bit duration, and interval between bits;...

  6. Photoelectric characterization of forward electron transfer to iron-sulfur centers in photosystem I

    SciTech Connect

    Leibl, W.; Toupance, B.; Breton, J.

    1995-08-15

    The photoelectric response of oriented PS1 membranes from the Synechocystis 6803 has been investigated in the nanosecond time range. There is a positive electrogenic phase with a rise time constant of 220 plus or minus 20 ns.

  7. METHOD FOR EXCHANGING ENERGY WITH A PLASMA BY MAGNETIC PUMPING

    DOEpatents

    Hall, L.S.

    1963-12-31

    A method of heating a plasma confined by a static magnetic field is presented. A time-varying magnetic field having a rise time to a predetermined value substantially less than its fall time is applied to a portion of the plasma. Because of the much shorter rise time, the plasma is reversibly heated. This cycle is repeated until the desired plasma temperature is reached. (AEC)

  8. Design concepts for a pulse power test facility to simulate EMP surges in overhead power lines. Part I. Fast pulse

    SciTech Connect

    Ramrus, A.

    1986-02-01

    Objective of the study was to create conceptual designs of high voltage pulsers capable of simulating two types of electromagnetic pulses (EMPs) caused by a high-altitude nuclear burst; the slow rise time magnetohydrodynamic (MHD-EMP) and the fast rise time high-altitude EMP (HEMP). The pulser design was directed towards facilities capable of performing EMP vulnerability testing of components used in the national electric power system.

  9. Effects of exercise and creatine on myosin heavy chain isoform composition in patients with Charcot-Marie-Tooth disease.

    PubMed

    Smith, Cheryl A; Chetlin, Robert D; Gutmann, Laurie; Yeater, Rachel A; Alway, Stephen E

    2006-11-01

    It is not known whether myosin heavy chain (MHC) content changes in response to exercise training or creatine supplementation in subjects with Charcot-Marie-Tooth disease (CMT). Based on previous data, we hypothesized that resistance exercise and creatine would increase the percentage of type I MHC composition in the vastus lateralis muscle and that myosin isoform changes would correlate with improved chair rise-time in CMT subjects. To test this hypothesis, 18 CMT subjects were randomly assigned to either a placebo or creatine group. All subjects performed a 12-week, home-based, moderate-intensity resistance training program. Chair rise-time was measured before and after the training program. Muscle biopsies were obtained from the vastus lateralis before and after the 12-week program. Gel electrophoresis showed a significant decrease (approximately 30%) in MHC type I in CMT subjects given creatine supplementation when compared with placebo. There was a nonsignificant increase in both MHC type IIa (approximately 23%) and MHC type IIx (approximately 7%) in CMT subjects given creatine. Reduced MHC type I content and increased MHC type IIa content correlated with faster chair rise-times (i.e., improved muscle performance). The training-induced change in MHC IIa content was inversely correlated with chair rise-time in CMT subjects given creatine. When the two subject groups were combined, there was a linear, negative relationship between the change in MHC type IIa content and chair rise-time after training and a positive relationship between the training-induced change in MHC type I content and chair rise-time. These data suggest that improved function (chair rise-time) was associated with a lower level of MHC type I and increased MHC type IIa composition. Furthermore, the data are consistent with the hypothesis that creatine supplementation alters MHC composition in CMT patients undergoing resistance training and that MHC changes associated with creatine

  10. Nonlinear propagation of high-frequency energy from blast waves as it pertains to bat hearing

    NASA Astrophysics Data System (ADS)

    Loubeau, Alexandra

    Close exposure to blast noise from military weapons training can adversely affect the hearing of both humans and wildlife. One concern is the effect of high-frequency noise from Army weapons training on the hearing of endangered bats. Blast wave propagation measurements were conducted to investigate nonlinear effects on the development of blast waveforms as they propagate from the source. Measurements were made at ranges of 25, 50, and 100 m from the blast. Particular emphasis was placed on observation of rise time variation with distance. Resolving the fine shock structure of blast waves requires robust transducers with high-frequency capability beyond 100 kHz, hence the limitations of traditional microphones and the effect of microphone orientation were investigated. Measurements were made with a wide-bandwidth capacitor microphone for comparison with conventional 3.175-mm (⅛-in.) microphones with and without baffles. The 3.175-mm microphone oriented at 90° to the propagation direction did not have sufficient high-frequency response to capture the actual rise times at a range of 50 m. Microphone baffles eliminate diffraction artifacts on the rise portion of the measured waveform and therefore allow for a more accurate measurement of the blast rise time. The wide-band microphone has an extended high-frequency response and can resolve shorter rise times than conventional microphones. For a source of 0.57 kg (1.25 lb) of C-4 plastic explosive, it was observed that nonlinear effects steepened the waveform, thereby decreasing the shock rise time, from 25 to 50 m. At 100m, the rise times had increased slightly. For comparison to the measured blast waveforms, several models of nonlinear propagation are applied to the problem of finite-amplitude blast wave propagation. Shock front models, such as the Johnson and Hammerton model, and full-waveform marching algorithms, such as the Anderson model, are investigated and compared to experimental results. The models

  11. Paths of Heritable Mitochondrial DNA Mutation and Heteroplasmy in Reference and gas-1 Strains of Caenorhabditis elegans

    PubMed Central

    Wernick, Riana I.; Estes, Suzanne; Howe, Dana K.; Denver, Dee R.

    2016-01-01

    Heteroplasmy—the presence of more than one mitochondrial DNA (mtDNA) sequence type in a cell, tissue, or individual—impacts human mitochondrial disease and numerous aging-related syndromes. Understanding the trans-generational dynamics of mtDNA is critical to understanding the underlying mechanisms of mitochondrial disease and evolution. We investigated mtDNA mutation and heteroplasmy using a set of wild-type (N2 strain) and mitochondrial electron transport chain (ETC) mutant (gas-1) mutant Caenorhabditis elegans mutation-accumulation (MA) lines. The N2 MA lines, derived from a previous experiment, were bottlenecked for 250 generations. The gas-1 MA lines were created for this study, and bottlenecked in the laboratory for up to 50 generations. We applied Illumina-MiSeq DNA sequencing to L1 larvae from five gas-1 MA lines and five N2 MA lines to detect and characterize mtDNA mutation and heteroplasmic inheritance patterns evolving under extreme drift. mtDNA copy number increased in both sets of MA lines: three-fold on average among the gas-1 MA lines and five-fold on average among N2 MA lines. Eight heteroplasmic single base substitution polymorphisms were detected in the gas-1 MA lines; only one was observed in the N2 MA lines. Heteroplasmy frequencies ranged broadly in the gas-1 MA lines, from as low as 2.3% to complete fixation (homoplasmy). An initially low-frequency (<5%) heteroplasmy discovered in the gas-1 progenitor was observed to fix in one gas-1 MA line, achieve higher frequency (37.4%) in another, and be lost in the other three lines. A similar low-frequency heteroplasmy was detected in the N2 progenitor, but was lost in all five N2 MA lines. We identified three insertion-deletion (indel) heteroplasmies in gas-1 MA lines and six indel variants in the N2 MA lines, most occurring at homopolymeric nucleotide runs. The observed bias toward accumulation of single nucleotide polymorphisms in gas-1 MA lines is consistent with the idea that impaired

  12. Paths of Heritable Mitochondrial DNA Mutation and Heteroplasmy in Reference and gas-1 Strains of Caenorhabditis elegans.

    PubMed

    Wernick, Riana I; Estes, Suzanne; Howe, Dana K; Denver, Dee R

    2016-01-01

    Heteroplasmy-the presence of more than one mitochondrial DNA (mtDNA) sequence type in a cell, tissue, or individual-impacts human mitochondrial disease and numerous aging-related syndromes. Understanding the trans-generational dynamics of mtDNA is critical to understanding the underlying mechanisms of mitochondrial disease and evolution. We investigated mtDNA mutation and heteroplasmy using a set of wild-type (N2 strain) and mitochondrial electron transport chain (ETC) mutant (gas-1) mutant Caenorhabditis elegans mutation-accumulation (MA) lines. The N2 MA lines, derived from a previous experiment, were bottlenecked for 250 generations. The gas-1 MA lines were created for this study, and bottlenecked in the laboratory for up to 50 generations. We applied Illumina-MiSeq DNA sequencing to L1 larvae from five gas-1 MA lines and five N2 MA lines to detect and characterize mtDNA mutation and heteroplasmic inheritance patterns evolving under extreme drift. mtDNA copy number increased in both sets of MA lines: three-fold on average among the gas-1 MA lines and five-fold on average among N2 MA lines. Eight heteroplasmic single base substitution polymorphisms were detected in the gas-1 MA lines; only one was observed in the N2 MA lines. Heteroplasmy frequencies ranged broadly in the gas-1 MA lines, from as low as 2.3% to complete fixation (homoplasmy). An initially low-frequency (<5%) heteroplasmy discovered in the gas-1 progenitor was observed to fix in one gas-1 MA line, achieve higher frequency (37.4%) in another, and be lost in the other three lines. A similar low-frequency heteroplasmy was detected in the N2 progenitor, but was lost in all five N2 MA lines. We identified three insertion-deletion (indel) heteroplasmies in gas-1 MA lines and six indel variants in the N2 MA lines, most occurring at homopolymeric nucleotide runs. The observed bias toward accumulation of single nucleotide polymorphisms in gas-1 MA lines is consistent with the idea that impaired

  13. Broadband ground-motion simulation using a hybrid approach

    USGS Publications Warehouse

    Graves, R.W.; Pitarka, A.

    2010-01-01

    This paper describes refinements to the hybrid broadband ground-motion simulation methodology of Graves and Pitarka (2004), which combines a deterministic approach at low frequencies (f 1 Hz). In our approach, fault rupture is represented kinematically and incorporates spatial heterogeneity in slip, rupture speed, and rise time. The prescribed slip distribution is constrained to follow an inverse wavenumber-squared fall-off and the average rupture speed is set at 80% of the local shear-wave velocity, which is then adjusted such that the rupture propagates faster in regions of high slip and slower in regions of low slip. We use a Kostrov-like slip-rate function having a rise time proportional to the square root of slip, with the average rise time across the entire fault constrained empirically. Recent observations from large surface rupturing earthquakes indicate a reduction of rupture propagation speed and lengthening of rise time in the near surface, which we model by applying a 70% reduction of the rupture speed and increasing the rise time by a factor of 2 in a zone extending from the surface to a depth of 5 km. We demonstrate the fidelity of the technique by modeling the strong-motion recordings from the Imperial Valley, Loma Prieta, Landers, and Northridge earthquakes.

  14. Time-resolved luminescence resonance energy transfer imaging of protein-protein interactions in living cells.

    PubMed

    Rajapakse, Harsha E; Miller, Lawrence W

    2012-01-01

    Lanthanide-based or luminescence resonance energy transfer (LRET) microscopy can be used to sensitively image interactions between reporter-labeled proteins in living mammalian cells. With LRET, luminescent lanthanide complexes are used as donors, conventional fluorophores are used as acceptors, and donor-sensitized acceptor emission occurs at time scales that reflect the long (~ms) lanthanide emission lifetime. These long-lived signals can be separated from short-lifetime (~ns) sample autofluorescence and directly excited acceptor fluorescence by using pulsed light to excite the specimen and by implementing a short delay (>100 ns) before detection, thereby increasing measurement sensitivity. As practical implementation of time-resolved LRET microscopy requires several potentially unfamiliar experimental techniques, we explicitly describe herein methods to label proteins in living mammalian cells with luminescent terbium complexes, image interactions between terbium-labeled proteins and green fluorescent protein fusions, and quantitatively analyze LRET images. PMID:22289461

  15. Calibration of the RSS-131 high efficiency ionization chamber for radiation dose monitoring during plasma experiments conducted on plasma focus device

    NASA Astrophysics Data System (ADS)

    Szewczak, Kamil; Jednoróg, Sławomir

    2014-10-01

    Plasma research poses a radiation hazard. Due to the program of deuterium plasma research using the PF-1000 device, it is an intensive source of neutrons (up to 1011 n · pulse -1) with energy of 2,45 MeV and ionizing electromagnetic radiation with a broad energy spectrum. Both types of radiation are mostly emitted in ultra-short pulses (˜100 ns). The aim of this work was to test and calibrate the RSS-131 radiometer for its application in measurements of ultra-short electromagnetic radiation pulses with broad energy spectrum emitted during PF-1000 discharge. In addition, the results of raw measurements performed in the control room are presented.

  16. Experimental investigation of silicon photomultipliers as compact light readout systems for gamma-ray spectroscopy applications in fusion plasmas.

    PubMed

    Nocente, M; Fazzi, A; Tardocchi, M; Cazzaniga, C; Lorenzoli, M; Pirovano, C; Rebai, M; Uboldi, C; Varoli, V; Gorini, G

    2014-11-01

    A matrix of Silicon Photo Multipliers has been developed for light readout from a large area 1 in. × 1 in. LaBr3 crystal. The system has been characterized in the laboratory and its performance compared to that of a conventional photo multiplier tube. A pulse duration of 100 ns was achieved, which opens up to spectroscopy applications at high counting rates. The energy resolution measured using radioactive sources extrapolates to 3%-4% in the energy range Eγ = 3-5 MeV, enabling gamma-ray spectroscopy measurements at good energy resolution. The results reported here are of relevance in view of the development of compact gamma-ray detectors with spectroscopy capabilities, such as an enhanced gamma-ray camera for high power fusion plasmas, where the use of photomultiplier is impeded by space limitation and sensitivity to magnetic fields. PMID:25430287

  17. Development and fabrication of low ON resistance high current vertical VMOS power FETs

    NASA Technical Reports Server (NTRS)

    Kay, S.

    1979-01-01

    The design of a VMOS Power FET exhibiting low ON resistance, high current as well as high breakdown voltage and fast switching speeds is described. The design which is based on a 1st-order device model, features a novel polysilicon-gate structure and fieldplated groove termination to achieve high packing density and high breakdown voltage, respectively. One test chip, named VNTKI, can block 180 V at an ON resistence of 2.5 ohm. A 150 mil x 200 mil (.19 sq cm) experimental chip has demonstrated a breakdown voltage of 200v, an ON resistance of 0.12 ohm, a switching time of less than 100 ns, and a pulse drain - current of 50 A with 10 V gate drive.

  18. OLA, A low-noise bipolar amplifier for the readout of Silicon Drift Detectors

    NASA Astrophysics Data System (ADS)

    Dabrowski, W.; Białas, W.; Bonazzola, G.; Bonvicini, V.; Ceretto, F.; Giubellino, P.; Idzik, M.; Prest, M.; Riccati, L.; Zampa, N.

    1995-11-01

    A very low noise, 32-channel preamplifier/shaper chip has been designed for the analogue readout of silicon detectors. The circuit has been optimised in view of the operation of Silicon Drift Detectors, which have very low capacitance and produce gaussian signals of σ up to ˜ 100 ns. The chip (OLA) has been designed and manufactured using the SHPi full-custom bipolar process by Tektronix. Each channel is composed by a preamplifier, a shaper and a symmetrical line driver, which allows to drive either a positive and a negative single ended output separately on 50 Ω impedance or a differential twisted pair. The intrinsic peaking time of the circuit is ˜ 60 ns, and the noise is below 250 electrons at zero input load capacitance. The power consumption is 2 mW/channel, mostly due to the output driver.

  19. Low-jitter, high-voltage, infrared, laser-triggered, vacuum switch

    SciTech Connect

    Earley, L.M.; Barnes, G.A.

    1991-01-01

    A laser-triggered, high-voltage vacuum switch using a triggering pellet embedded in the cathode has been developed. The switch was constructed with tungsten electrodes and used either KC1 or Poco graphite pellets. An aperture in the anode allowed the laser beam to strike the pellet on the cathode surface. Reliable triggering was achieved with only 200 {mu}J of laser energy at a wavelength of 1064 nm. The switch was operated with an A-K gap voltage ranging from 5- to 30-kV with switching currents up to 15 kA peak. The delay time of the switch vaired from 70 {plus minus} 3 ns at 25 kv to 500 {plus minus} 100 ns at 5 kV. 6 refs., 6 figs., 2 tabs.

  20. High repetition ration solid state switched CO2 TEA laser employed in industrial ultrasonic testing of aircraft parts

    NASA Astrophysics Data System (ADS)

    von Bergmann, Hubertus; Morkel, Francois; Stehmann, Timo

    2015-02-01

    Laser Ultrasonic Testing (UT) is an important technique for the non-destructive inspection of composite parts in the aerospace industry. In laser UT a high power, short pulse probe laser is scanned across the material surface, generating ultrasound waves which can be detected by a second low power laser system and are used to draw a defect map of the part. We report on the design and testing of a transversely excited atmospheric pressure (TEA) CO2 laser system specifically optimised for laser UT. The laser is excited by a novel solid-state switched pulsing system and utilises either spark or corona preionisation. It provides short output pulses of less than 100 ns at repetition rates of up to 1 kHz, optimised for efficient ultrasonic wave generation. The system has been designed for highly reliable operation under industrial conditions and a long term test with total pulse counts in excess of 5 billion laser pulses is reported.

  1. Stopping Narrow-Band X-Ray Pulses in Nuclear Media

    NASA Astrophysics Data System (ADS)

    Kong, Xiangjin; Pálffy, Adriana

    2016-05-01

    A control mechanism for stopping x-ray pulses in resonant nuclear media is investigated theoretically. We show that narrow-band x-ray pulses can be mapped and stored as nuclear coherence in a thin-film planar x-ray cavity with an embedded 57Fe nuclear layer. The pulse is nearly resonant to the 14.4 keV Mössbauer transition in the 57Fe nuclei. The role of the control field is played here by a hyperfine magnetic field which induces interference effects reminiscent of electromagnetically induced transparency. We show that, by switching off the control magnetic field, a narrow-band x-ray pulse can be completely stored in the cavity for approximately 100 ns. Additional manipulation of the external magnetic field can lead to both group velocity and phase control of the pulse in the x-ray cavity sample.

  2. Emission Spectrochemical Analysis of Food Material Using TEA CO2 Laser-Induced Shock Wave Plasma

    NASA Astrophysics Data System (ADS)

    Kagawa, Kiichiro; Deguchi, Yoji; Ogata, Akira; Kurniawan, Hendrick; Ikeda, Noriko; Takagi, Yasuhiro

    1991-11-01

    A new method for spectrochemical analysis of food materials is presented using a Transverse Excited Atmospheric (TEA) CO2 laser. Milk powders containing different amounts of Ca are mixed with KBr powder, and compressed to make pellets. The pellets are bombarded by the TEA CO2 laser (300 mJ, 100 ns) under the surrounding gas of 300 Pa. The shape of the luminous plasma is hemispherical. This plasma is excited by the shock wave induced by the laser bombardment. It is proved that the relative intensity of the Ca 422.6-nm emission line to that of the K 404.4-nm emission line is proportional to the Ca content. This method has a bright prospect as a direct analytical method of food materials.

  3. Temporal response of a surface flashover on a velvet cathode in a relativistic diode

    SciTech Connect

    Coleman, J. E.; Moir, D. C.; Crawford, M. T.; Welch, D. R.; Offermann, D. T.

    2015-03-11

    Surface flashover of a carbon fiber velvet cathode generates a discharge from which electrons are relativistically accelerated to γ ranging from 4.9 to 8.8 through a 17.8 cm diode. It is assumed that this discharge is a hydrocarbon mixture. Our principal objective of these experiments is to quantify the dynamics over the ~100 ns pulse of the plasma discharge generated on the surface of the velvet cathode and across the anode-cathode (A-K) gap. A qualitative comparison of calculated and measured results is presented, which includes time resolved measurements with a photomultiplier tube and charge-coupled device images. Additionally, initial visible spectroscopy measurements will also be presented confirming the ion species are dominated by hydrogen.

  4. Self-assembling of zinc phthalocyanines on ZnO (1010) surface through multiple time scales.

    PubMed

    Melis, Claudio; Raiteri, Paolo; Colombo, Luciano; Mattoni, Alessandro

    2011-12-27

    We adopt a hierarchic combination of theoretical methods to study the assembling of zinc phthalocyanines (ZnPcs) on a ZnO (1010) surface through multiple time scales. Atomistic simulations, such as model potential molecular dynamics and metadynamics, are used to study the energetics and short time evolution (up to ∼100 ns) of small ZnPc aggregates. The stability and the lifetime of large clusters is then studied by means of an atomistically informed coarse-grained model using classical molecular dynamics. Finally, the macroscopic time scale clustering phenomenon is studied by Metropolis Monte Carlo algorithms as a function of temperature and surface coverage. We provide evidence that at room temperature the aggregation is likely to occur at sufficiently high coverage, and we characterize the nature, morphology, and lifetime of ZnPc's clusters. We identify the molecular stripes oriented along [010] crystallographic directions as the most energetically stable aggregates.

  5. An atmospheric-pressure plasma brush driven by sub-microsecond voltage pulses

    NASA Astrophysics Data System (ADS)

    Lu, X.; Wu, S.; Chu, Paul K.; Liu, D.; Pan, Y.

    2011-12-01

    An atmospheric-pressure room-temperature plasma brush, which can deliver uniform surface treatment effects, is reported. The plasma structure, which includes the negative glow, Faraday dark space and positive column, is clearly visible to the naked eye. The width of the Faraday dark space diminishes with decreasing gap distance and this phenomenon is different from that observed from low-pressure glow discharge plasmas. High-speed photographs taken at an exposure time of 2.5 ns show that the plasma propagates from the nozzle to the object in about 100 ns and 10 ns for gap distances of 6 mm and 2 mm, respectively, and the results are consistent with electric measurements. The emission spectra reveal N2(B-A) bands in addition to those of O, N_2^+ , N2(C-B) and He, indicating that the plasma source is reactive and suitable for applications such as surface modification and materials processing.

  6. A Large Aperture, High Energy Laser System for Optics and Optical Component Testing

    SciTech Connect

    Nostrand, M C; Weiland, T L; Luthi, R L; Vickers, J L; Sell, W D; Stanley, J A; Honig, J; Auerbach, J; Hackel, R P; Wegner, P J

    2003-11-01

    A large aperture, kJ-class, multi-wavelength Nd-glass laser system has been constructed at Lawrence Livermore National Lab which has unique capabilities for studying a wide variety of optical phenomena. The master-oscillator, power-amplifier (MOPA) configuration of this ''Optical Sciences Laser'' (OSL) produces 1053 nm radiation with shaped pulse lengths which are variable from 0.1-100 ns. The output can be frequency doubled or tripled with high conversion efficiency with a resultant 100 cm{sup 2} high quality output beam. This facility can accommodate prototype hardware for large-scale inertial confinement fusion lasers allowing for investigation of integrated system issues such as optical lifetime at high fluence, optics contamination, compatibility of non-optical materials, and laser diagnostics.

  7. Electrothermal instability growth in magnetically driven pulsed power liners

    SciTech Connect

    Peterson, Kyle J.; Sinars, Daniel B.; Yu, Edmund P.; Herrmann, Mark C.; Cuneo, Michael E.; Slutz, Stephen A.; Smith, Ian C.; Atherton, Briggs W.; Knudson, Marcus D.; Nakhleh, Charles

    2012-09-15

    This paper explores the role of electro-thermal instabilities on the dynamics of magnetically accelerated implosion systems. Electro-thermal instabilities result from non-uniform heating due to temperature dependence in the conductivity of a material. Comparatively little is known about these types of instabilities compared to the well known Magneto-Rayleigh-Taylor (MRT) instability. We present simulations that show electrothermal instabilities form immediately after the surface material of a conductor melts and can act as a significant seed to subsequent MRT instability growth. We also present the results of several experiments performed on Sandia National Laboratories Z accelerator to investigate signatures of electrothermal instability growth on well characterized initially solid aluminum and copper rods driven with a 20 MA, 100 ns risetime current pulse. These experiments show excellent agreement with electrothermal instability simulations and exhibit larger instability growth than can be explained by MRT theory alone.

  8. Monopolar photoelectromagnetic effect in Pb1-xSnxTe(In) under terahertz laser radiation

    NASA Astrophysics Data System (ADS)

    Chernichkin, V. I.; Ryabova, L. I.; Nicorici, A. V.; Khokhlov, D. R.

    2012-03-01

    We report on the observation of a new effect—the appearance of a galvanic signal in the narrow-gap semiconductor Pb1-xSnxTe(In) in the magnetic field under the action of strong 100 ns-long terahertz laser pulses. The signal changes its sign and kinetics as the temperature increases from 4.2 K to 25 K. This semiconductor possesses inversion symmetry of the crystalline lattice making impossible the observation of the magnetophotogalvanic effect which looks similar in its experimental manifestation. On the other hand, the laser quantum energy is much less than the bandgap of the semiconductor making the effect considerably different from the conventional Kikoin-Noskov photoelectromagnetic effect. Possible mechanisms responsible for the appearance of the effect are discussed.

  9. Analysis of water channels by molecular dynamics simulation of heterotetrameric sarcosine oxidase

    PubMed Central

    Watanabe, Go; Nakajima, Daisuke; Hiroshima, Akinori; Suzuki, Haruo; Yoneda, Shigetaka

    2015-01-01

    A precise 100-ns molecular dynamics simulation in aquo was performed for the heterotetrameric sarcosine oxidase bound with a substrate analogue, dimethylglycine. The spatial region including the protein was divided into small rectangular cells. The average number of the water molecules locating within each cell was calculated based on the simulation trajectory. The clusters of the cells filled with water molecules were used to determine the water channels. The narrowness of the channels, the average hydropathy indices of the residues of the channels, and the number of migration events of water molecules through the channels were consistent with the selective transport hypothesis whereby tunnel T3 is the pathway for the exit of the iminium intermediate of the enzyme reaction. PMID:27493862

  10. Efficient light storage with reduced energy loss via nonlinear compensation in rubidium vapor

    NASA Astrophysics Data System (ADS)

    Wang, Gang; Zhou, Wei; Chen, Hong-Li; Xue, Yan; Wu, Jin-Hui; Xu, Huai-Liang; Gao, Jin-Yue

    2016-06-01

    We report an experimental demonstration of efficient light storage based on a modified technique of electromagnetically induced transparency in hot rubidium vapor. By introducing an auxiliary pump field to go beyond the Λ -type configuration, we find that the undesired four-wave mixing can be greatly suppressed to result in sufficiently reduced energy loss of a probe pulse. The light storage efficiency can be as high as  ∼80% within the storage time of 100 ns with the pump field applied, which is almost 6 times larger than that in the absence of the pump field. We may also amend the light storage efficiency in a linear way by increasing the optical depth of our atomic vapor even without saturation effect. We obtain, in fact, an amplified probe pulse via Raman gain during light storage and retrieval, which should have practical applications in classical and quantum information processing.

  11. Microcontroller-based binary integrator for millimeter-wave radar experiments

    NASA Astrophysics Data System (ADS)

    Eskelinen, Pekka; Ruoskanen, Jukka; Peltonen, Jouni

    2010-05-01

    An easily on-site reconfigurable multiple binary integrator for millimeter radar experiments has been constructed of static random access memories, an eight bit microcontroller, and high speed video operational amplifiers. The design uses a raw comparator path and two adjustable m-out-of-n chains in a wired-OR configuration. Standard high speed memories allow the use of pulse widths below 100 ns. For eight pulse repetition intervals it gives a maximum improvement of 6.6 dB for stationary low-level target echoes. The doubled configuration enhances the capability against fluctuating targets. Because of the raw comparator path, also single return pulses of relatively high amplitude are processed.

  12. Characterization of a Surface-Flashover Ion Source with 10 - 250 ns Pulse Width

    SciTech Connect

    Falabella, S; Guethlein, G; Kerr, P L; Meyer, G A; Sampayan, S E; Tang, V; Morse, J D

    2008-08-05

    As a step towards developing an ultra compact D-D neutron source for various defense and homeland security applications, a compact ion source is needed. Towards that end, we are testing a pulsed, surface flashover source, with deuterated titanium films deposited on alumina substrates as the electrodes. An electrochemically-etched mask was used to define the electrode areas on the substrate during the sputtered deposition of the titanium films. Deuterium loading of the films was performed in an all metal-sealed vacuum chamber containing a heated stage. Deuterium ion current from the source was determined by measuring the neutrons produced when the ions impacted a deuterium-loaded target held at -90 kV. As the duration of the arc current is varied, it was observed that the integrated deuteron current per pulse initially increases rapidly, then reaches a maximum near a pulse length of 100 ns.

  13. Temporal evolution of electron density and temperature in capillary discharge plasmas

    SciTech Connect

    Oh, Seong Y.; Kang, Hoonsoo; Uhm, Han S.; Lee, In W.; Suk, Hyyong

    2010-05-15

    Time-resolved spectroscopic measurements of a capillary discharge plasma of helium gas were carried out to obtain detailed information about dynamics of the discharge plasma column, where the fast plasma dynamics is determined by the electron density and temperature. Our measurements show that the electron density of the capillary plasma column increases sharply after gas breakdown and reaches its peak of the order of 10{sup 18} cm{sup -3} within less than 100 ns, and then it decreases as time goes by. The result indicates that a peak electron density of 2.3x10{sup 18} cm{sup -3} occurs about 65 ns after formation of the discharge current, which is ideal for laser wakefield acceleration experiments reported by Karsch et al. [New J. Phys. 9, 415 (2007)].

  14. The effects of steep-front, short-duration impulses on power distribution components

    SciTech Connect

    Miller, D.B.; Lux, A.E.; Grzybowski, Stanislaw; Barnes, P.R.

    1989-07-01

    A line type pulser has been developed to test the effects of steep-front, short duration (SFSD) pulses on distribution components. Risetime is 50-100 ns, and pulse duration is on the order of 300 ns. Terminators often shattered or punctured rather than flashing over. Insulator flashover voltage is approximately 1.5 times CFO for standard lightning impulses. Arresters exhibit an inductive character, with SFSD peak voltage at 10 kA approximately 4--5 times the 8 /times/ 20 microsecond 10 kA discharge voltage. Polyethylene insulated cable has a characteristic degradation in which failure voltage decreases with number of SFSD pulses. 7 refs., 12 figs., 2 tabs.

  15. Study of Discharging Characteristics of Hollow Cathode Surge Protective Gap

    NASA Astrophysics Data System (ADS)

    Yao, Xueling; Chen, Jingliang; Xu, Xiaowei; Liu, Yong; Zhao, Yong

    2010-02-01

    A hollow cathode surge protective gap (HCSPG) was designed, and the discharge characteristics was investigated in an air and nitrogen gas environment. For both the gap spacing D and the hole diameter varphi of HCSPG of 3 mm, the voltage protective value Up of HCSPG is about 3.5 kV and its converting time tc exceeds 100 ns at an air pressure from 10 Pa to 100 Pa. The maximum converting time tc from glow to arc discharging reaches 1600 ns at an air pressure of 100 Pa, while the minimum converting time tc is 120 ns at 10 Pa. For a triggered HCSPG, Up is reduced to about 1.6 kV while the converting time is 120 ns with a semiconductor trigger device and 50 ns with a dielectric porcelain trigger device under an air pressure of 100 Pa.

  16. High brightness diode-pumped organic solid-state laser

    NASA Astrophysics Data System (ADS)

    Zhao, Zhuang; Mhibik, Oussama; Nafa, Malik; Chénais, Sébastien; Forget, Sébastien

    2015-02-01

    High-power, diffraction-limited organic solid-state laser operation has been achieved in a vertical external cavity surface-emitting organic laser (VECSOL), pumped by a low-cost compact blue laser diode. The diode-pumped VECSOLs were demonstrated with various dyes in a polymer matrix, leading to laser emissions from 540 nm to 660 nm. Optimization of both the pump pulse duration and output coupling leads to a pump slope efficiency of 11% for a DCM based VECSOLs. We report output pulse energy up to 280 nJ with 100 ns long pump pulses, leading to a peak power of 3.5 W in a circularly symmetric, diffraction-limited beam.

  17. Conformational space of clindamycin studied by ab initio and full-atom molecular dynamics.

    PubMed

    Kulczycka-Mierzejewska, Katarzyna; Trylska, Joanna; Sadlej, Joanna

    2016-01-01

    Molecular dynamics (MD) simulations allow determining internal flexibility of molecules at atomic level. Using ab initio Born-Oppenheimer molecular dynamics (BOMD), one can simulate in a reasonable time frame small systems with hundreds of atoms, usually in vacuum. With quantum mechanics/molecular mechanics (QM/MM) or full-atom molecular dynamics (FAMD), the influence of the environment can also be simulated. Here, we compare three types of MD calculations: ab initio BOMD, hybrid QM/MM, and classical FAMD. As a model system, we use a small antibiotic molecule, clindamycin, which is one of the lincosamide antibiotics. Clindamycin acquires two energetically stable forms and we investigated the transition between these two experimentally known conformers. We performed 60-ps BOMD simulations in vacuum, 50-ps QM/MM, and 100-ns FAMD in explicit water. The transition between two antibiotic conformers was observed using both BOMD and FAMD methods but was not noted in the QM/MM simulations. PMID:26733483

  18. Online Tracking Algorithms on GPUs for the P̅ANDA Experiment at FAIR

    NASA Astrophysics Data System (ADS)

    Bianchi, L.; Herten, A.; Ritman, J.; Stockmanns, T.; Adinetz, A.; Kraus, J.; Pleiter, D.

    2015-12-01

    P̅ANDA is a future hadron and nuclear physics experiment at the FAIR facility in construction in Darmstadt, Germany. In contrast to the majority of current experiments, PANDA's strategy for data acquisition is based on event reconstruction from free-streaming data, performed in real time entirely by software algorithms using global detector information. This paper reports the status of the development of algorithms for the reconstruction of charged particle tracks, optimized online data processing applications, using General-Purpose Graphic Processing Units (GPU). Two algorithms for trackfinding, the Triplet Finder and the Circle Hough, are described, and details of their GPU implementations are highlighted. Average track reconstruction times of less than 100 ns are obtained running the Triplet Finder on state-of- the-art GPU cards. In addition, a proof-of-concept system for the dispatch of data to tracking algorithms using Message Queues is presented.

  19. Dense Plasma Focus as Collimated Source of D-D Fusion Neutron Beams for Irradiation Experiences and Study of Emitted Radiations

    SciTech Connect

    Milanese, M.; Niedbalski, J.; Moroso, R.; Guichon, S.; Supan, J.

    2008-04-07

    A 'table-top' 2 kJ, 250 kA plasma focus, the PACO (Plasma AutoConfinado), designed by the Dense Plasma Group of IFAS is used in its optimum regime for neutron yield for obtaining collimated pulsed neutron beams (100 ns). A simple and low-cost shielding arrangement was developed in order to fully eliminate the 2.45 MeV neutrons generated in the PACO device (10{sup 8} per shot at 31 kV, 1-2 mbar). Conventional neutron diagnostics: scintillator-photomultiplier (S-PMT), silver activation counters (SAC), etc., are used to determine the minimum width of the shielding walls. Emission of very hard electromagnetic pulses is also studied. Collimation using lead and copper plates is made to determine the localization of the very hard X-ray source. The maximum energy of the continuum photon distribution is estimated in 0,6 MeV using a system of filters.

  20. Mössbauer spectra obtained using β - γ coincidence method after 57Mn implantation into LiH and LiD

    NASA Astrophysics Data System (ADS)

    Sato, Y.; Kobayashi, Y.; Yamada, Y.; Kubo, M. K.; Mihara, M.; Nagatomo, T.; Sato, W.; Miyazaki, J.; Tanigawa, S.; Natori, D.; Sato, S.; Kitagawa, A.

    2016-12-01

    Highly energetic 57Mn ( T 1/2 = 1.45 m) was generated by nuclear projectile fragmentation in a heavy-ion accelerator, and implanted into lithium hydride (LiH) and lithium deuteride (LiD) at 578 K. Mössbauer spectroscopy with β - γ coincidence detection was then carried out on the 57Fe obtained from β -decay of the 57Mn to study the time dependence of the site distributions and coordination environments of dilute Fe atoms implanted in the LiH and LiD. The results suggest that the Fe atoms can substitute for either the Li and H or D atoms within 100 ns. Additionally, the displacement behavior of the substitutional 57Fe atoms on the lattice sites is discussed.

  1. STIRAP schemes for atomic Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Thomasen, Andreas M. D.; Byrnes, Tim

    2016-09-01

    In coherent control of Bose-Einstein condensates (BEC) the major limitation to successful high fidelity transfer using optical Raman transitions is spontaneous emission of radiation and the decoherence that this causes. We present a scheme based on stimulated Raman adiabatic passage (STIRAP) designed specifically for Rubidium 87. STIRAP is a method of population transfer that relies on the adiabatic theorem of quantum mechanics. Instead of transferring population between Hamiltonian ground states, one adiabatically evolves the ground states into some desired superposition. We show that one may thereby implement arbitrary rotations of spinor BECs with extremely high fidelities. Our simulations show that given a BEC with N = 104 atoms, we may do an arbitrary unitary rotation with an infidelity of about 10-7 that takes approximately 100 ns.

  2. Ultraviolet photosensitivity of sulfur-doped micro- and nano-crystalline diamond

    SciTech Connect

    Mendoza, Frank; Makarov, Vladimir; Hidalgo, Arturo; Weiner, Brad; Morell, Gerardo

    2011-06-06

    The room-temperature photosensitivity of sulfur-doped micro- (MCD), submicro- (SMCD) and nano- (NCD) crystalline diamond films synthesized by hot-filament chemical vapor deposition was studied. The structure and composition of these diamond materials were characterized by Raman spectroscopy, scanning electron microscopy and X-ray diffraction. The UV sensitivity and response time were studied for the three types of diamond materials using a steady state broad UV excitation source and two pulsed UV laser radiations. It was found that they have high sensitivity in the UV region, as high as 109 sec-1mV-1 range, linear response in a broad spectral range below 320 nm, photocurrents around ~10-5 A, and short response time better than 100 ns, which is independent of fluency intensity. A phenomenological model was applied to help understand the role of defects and dopant concentration on the materials’ photosensitivity.

  3. Possibility of applying a hydrodynamic model to describe the laser erosion of metals irradiated by high-intensity nanosecond pulses

    SciTech Connect

    Kozadaev, K V

    2014-04-28

    We report the results of experimental investigations of the production and development of plasma-vapour plumes upon irradiation of metal targets by nanosecond (10–100 ns) pulses with a high (10{sup 8}–10{sup 10} W cm{sup -2}) power density under atmospheric conditions. The transition from a quasi-stationary thermal mechanism of metal erosion to an explosion hydrodynamic one takes place when the radiation power density increases from 10{sup 8} to 10{sup 9} W cm{sup -2}. The resultant experimental information is extremely important for the laser deposition of metal nanostructures under atmospheric conditions, which is possible only for power densities of 10{sup 8}–10{sup 9} W cm{sup -2}. (interaction of laser radiation with matter)

  4. Ultraviolet photosensitivity of sulfur-doped micro- and nano-crystalline diamond

    DOE PAGES

    Mendoza, Frank; Makarov, Vladimir; Hidalgo, Arturo; Weiner, Brad; Morell, Gerardo

    2011-06-06

    The room-temperature photosensitivity of sulfur-doped micro- (MCD), submicro- (SMCD) and nano- (NCD) crystalline diamond films synthesized by hot-filament chemical vapor deposition was studied. The structure and composition of these diamond materials were characterized by Raman spectroscopy, scanning electron microscopy and X-ray diffraction. The UV sensitivity and response time were studied for the three types of diamond materials using a steady state broad UV excitation source and two pulsed UV laser radiations. It was found that they have high sensitivity in the UV region, as high as 109 sec-1mV-1 range, linear response in a broad spectral range below 320 nm, photocurrentsmore » around ~10-5 A, and short response time better than 100 ns, which is independent of fluency intensity. A phenomenological model was applied to help understand the role of defects and dopant concentration on the materials’ photosensitivity.« less

  5. The Eagle Nebula on NIF

    NASA Astrophysics Data System (ADS)

    Kane, Jave; Cooper, Amy; Remington, Bruce; Ryutov, Dmitri; Smalyuk, Vladimir; Pound, Marc

    2011-10-01

    In one of the eight Science on NIF campaigns, dynamics of molecular clouds such as the Eagle Nebula will be studied in scaled laboratory astrophysics experiments, focusing on new hydrodynamic stabilities of ablation fronts induced by strong directionality of a sustained radiation drive, and on the formation of cometary structures as a model for the famous Eagle Pillars. The NIF Radiation Transport Platform will be adapted to drive a foam target stood off several mm from the halfraum to simulate a molecular cloud illuminated by a distant O-type star, with the drive collimated by an aperture. Pulses of length 20-100 ns generating effective radiation temperatures of 100 eV are being sought. Design of the experiment, theory of the directional radiation instabilities, and supporting astrophysical modeling will be presented. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  6. High-power dielectric Cherenkov maser oscillator experiments

    SciTech Connect

    Main, W. . Lab. for Plasma Research); Cherry, R. ); Garate, E. )

    1990-06-01

    This paper presents the results of a series of experiments conducted on the dielectric Cherenkov maser (DCM) oscillator. The device consists of a cylindrical metallic waveguide of inner radius 3.64 cm which is partially filled with a dielectric liner. Traveling through the lined waveguide is an annular relativistic electron beam. Liners of dielectric constant {epsilon} = 10, 5 and 2.3 were investigated for liner thicknesses of 4 and 6 mm. The 6-mm-thick, {epsilon} = 10 liner generated an RF output of 200 MW for 20 ns at 3.8 Hz with electron-beam parameters of 700 kV, 12 kA, and pulse duration of 100 ns. The maximum measured power output for the other configurations was 80 MW at a frequency of 7 GHz ({epsilon} = 5), with several MW of power output from the polyethylene liner ({epsilon} = 2.3) at a frequency of {approximately} 9 GHz.

  7. A frequency-locked, high-power, X-band dielectric Cerenkov maser

    SciTech Connect

    Weatherall, J.C. )

    1992-06-01

    Most research on the dielectric Cerenkov maser (DCM) has focused only on free running oscillators. Presented in this paper, is a high-power frequency-locked oscillator. The device consists of an annular electron beam traveling down a dielectric-lined waveguide (wall radius 1.74 cm, liner thickness 2-3 mm, liner {epsilon} = 10). A 100 kW input signal is injected into the drift tube between the diode and liner, through a rectangular TE{sub 10} to cylindrical TM{sub 01} mode converter. When operated with a beam current of 500 A and a total output power of 13 MW, the device displays no RF quenching through the full width of the 100 ns beam pulse. Two higher current cases are presented with power as high as 280 MW but severe RF quenching. The results are compared with linear theory, and quenching mechanisms are discussed.

  8. 1.95  μm-pumped OP-GaAs optical parametric oscillator with 10.6  μm idler wavelength.

    PubMed

    Wueppen, Jochen; Nyga, Sebastian; Jungbluth, Bernd; Hoffmann, Dieter

    2016-09-15

    We report on an optical parametric oscillator that generates output idler wavelengths around 10.6 μm. On the basis of orientation-patterned gallium arsenide (OP-GaAs) as a nonlinear medium and a 1.95 μm ns-pulsed pump laser, a signal-resonant bow-tie resonator was designed in order to maximize the output power at moderate intensities well below the damage threshold of the optical components. With this setup, the average idler output power at 50 kHz and 100 ns idler pulse length was more than 800 mW, which corresponds to a pulse energy of 16 μJ. The maximum quantum conversion efficiency of 36.8% is the highest value measured so far for comparable setups to the best of our knowledge. PMID:27628363

  9. Plasma and laser kinetics and field emission from carbon nanotube fibers for an Advanced Noble Gas Laser (ANGL)

    NASA Astrophysics Data System (ADS)

    Moran, Paul J.; Lockwood, Nathaniel P.; Lange, Matthew A.; Hostutler, David A.; Guild, Eric M.; Guy, Matthew R.; McCord, John E.; Pitz, Greg A.

    2016-03-01

    A metastable argon laser operating at 912 nm has been demonstrated by optically pumping with a pulsed titanium sapphire laser to investigate the temporal dynamics of an Advanced Noble Gas Laser (ANGL). Metastable argon concentrations on the order of 1011 cm-3 were maintained with the use of a radio frequency (RF) capacitively coupled discharge. The end-pumped laser produced output powers under 2 mW of average power with pulse lengths on the order of 100 ns. A comparison between empirical results and a four level laser model using longitudinally average pump and inter-cavity intensities is made. An alternative, highly-efficient method of argon metastable production for ANGL was explored using carbon nanotube (CNT) fibers.

  10. X-ray absorption spectroscopy on the basis of hybrid X-pinch radiation

    SciTech Connect

    Tilikin, I. N. Shelkovenko, T. A.; Pikuz, S. A.; Knapp, P. F.; Hammer, D. A.

    2015-07-15

    Results of experiments on X-ray absorption spectroscopy carried out at the BIN (270 kA, 100 ns) and XP (450 kA, 45 ns) facilities are presented. Continuum radiation of a Mo hybrid X-pinch was used as probing radiation, against which absorption lines of the plasma of exploded Al wires placed in the return current circuit of a hybrid X-pinch, as well as in a two- and four-wire array, were observed. The experiments have demonstrated that the radiation of a hybrid X-pinch hot spot can be used as probing radiation for X-ray absorption spectroscopy and that, in many parameters, such a source surpasses those on the basis of laser-produced plasma. The plasma parameters in arrays made of two and four Al wires were studied experimentally.

  11. Computational modeling of Krypton gas puffs with tailored mass density profiles on Z

    DOE PAGES

    Jennings, Christopher A.; Ampleford, David J.; Lamppa, Derek C.; Hansen, Stephanie B.; Jones, Brent Manley; Harvey-Thompson, Adam James; Jobe, Marc Ronald Lee; Reneker, Joseph; Rochau, Gregory A.; Cuneo, Michael Edward; et al

    2015-05-18

    Large diameter multi-shell gas puffs rapidly imploded by high current (~20 MA, ~100 ns) on the Z generator of Sandia National Laboratories are able to produce high-intensity Krypton K-shell emission at ~13 keV. Efficiently radiating at these high photon energies is a significant challenge which requires the careful design and optimization of the gas distribution. To facilitate this, we hydrodynamically model the gas flow out of the nozzle and then model its implosion using a 3-dimensional resistive, radiative MHD code (GORGON). This approach enables us to iterate between modeling the implosion and gas flow from the nozzle to optimize radiativemore » output from this combined system. Furthermore, guided by our implosion calculations, we have designed gas profiles that help mitigate disruption from Magneto-Rayleigh–Taylor implosion instabilities, while preserving sufficient kinetic energy to thermalize to the high temperatures required for K-shell emission.« less

  12. Stack optimization of oxide-based RRAM for fast write speed (<1 μs) at low operating current (<10 μA)

    NASA Astrophysics Data System (ADS)

    Chen, C. Y.; Goux, L.; Fantini, A.; Degraeve, R.; Redolfi, A.; Groeseneken, G.; Jurczak, M.

    2016-11-01

    In this paper we engineer a TiN ⧹ Al2O3 ⧹ (Hf,Al)O2 ⧹ Ta2O5 ⧹ Hf Oxide Resistive Random Access Memory (OxRRAM) device for fast switching at low operation current without sacrificing the retention and endurance properties. The integrated 40 nm × 40 nm cell switches at 10 μA using write pulses shorter than 100 ns (resp. 1 μs) for Reset (resp. Set) and with amplitude <2 V. Using these conditions in a specially developed verify algorithm, a resistive window of 10× is reliably obtained, decreasing the write speed by more than 1 decade compared to state-of-the-art OxRRAM stacks at same current level.

  13. Laser damage studies of metal mirrors and ZnSe optics by long-pulse and TEA-CO2 lasers at 10.6 μm

    NASA Astrophysics Data System (ADS)

    Plass, Wilfried; Krupka, Rene; Giesen, Adolf; Reedy, Herman E.; Kennedy, Michael; Ristau, Detlev

    1994-07-01

    Single shot laser damage studies have been performed using an RF-excited long pulse laser and a TEA-CO2-laser with pulse durations of 1.2 ms and 100 ns, respectively. Besides bare diamond turned copper mirrors with different metal and dielectric coatings, ZnSe-optics with selected coating types were tested. The temporal damage behavior in the long pulse regime was investigated on the basis of a damage detection system with a time resolution of 10 microsecond(s) . The dependence of the damage threshold on the intensity is discussed in consideration of the integral absorptance of the coatings. The measured damage thresholds of this detection system are compared to those obtained by Nomarski/darkfield microscopy. The local variation of the laser induced damage threshold is correlated to the corresponding photothermal deflection signal, reflectance, and defect density of the coated surfaces.

  14. Diamond detector for beam profile monitoring in COMET experiment at J-PARC

    NASA Astrophysics Data System (ADS)

    &Cbreve; erv, M.; Sarin, P.; Pernegger, H.; Vageeswaran, P.; Griesmayer, E.

    2015-06-01

    We present the design and initial prototype results of a proton beam profile monitor for the COMET experiment at J-PARC. The goal of COMET is to look for charged lepton flavor violation by direct μ to e conversion at a sensitivity of 10-19. The 8 GeV proton beam pulsed at 100 ns with 1010 protons/s will be used to create muons through pion production and decay. In the final experiment, the proton flux will be raised to 1014 protons/s to increase the sensitivity. These requirements of harsh radiation tolerance and fast readout make diamond a good choice for constructing a beam profile monitor in COMET. We present first results of the characterization of single crystal diamond (scCVD) sourced from a new company 2A SYSTEMS Singapore. Our measurements indicate excellent charge collection and high carrier mobility down to cryogenic temperatures.

  15. Trigger Data Serializer ASIC chip for the ATLAS New Small Wheel sTGC Detector

    NASA Astrophysics Data System (ADS)

    Meng, Xiangting; Wang, Jinhong; Guan, Liang; Sang, Ziru; Chapman, John; Zhou, Bing; Zhu, Junjie

    2015-04-01

    The small-strip thin-gap chambers (sTGC) will be used as the trigger device for the Phase-I upgrade of the ATLAS new small wheel (nSW) muon detector. An Application-Specific Integrated Circuit (ASIC) chip is needed to collect digital signals from both pad and strip detectors and serialize the outputs to the circuitry located on the rim of the nSW. The large number of input channels (128 differential input channels), short time available to prepare and transmit trigger data (<100 ns), high speed output data rate (4.8 Gbps), harsh radiation environment (about 300 kRad), and low power consumption (<1 W) impose great challenges for the design of this ASIC chip using the IBM 130 nm CMOS process. We will present our design and test results based on the prototype chip we build.

  16. Using Two-Dimensional Distributed Feedback for Synchronization of Radiation from Two Parallel-Sheet Electron Beams in a Free-Electron Maser

    NASA Astrophysics Data System (ADS)

    Arzhannikov, A. V.; Ginzburg, N. S.; Kalinin, P. V.; Kuznetsov, S. A.; Malkin, A. M.; Peskov, N. Yu.; Sergeev, A. S.; Sinitsky, S. L.; Stepanov, V. D.; Thumm, M.; Zaslavsky, V. Yu.

    2016-09-01

    A spatially extended planar 75 GHz free-electron maser with a hybrid two-mirror resonator consisting of two-dimensional upstream and traditional one-dimensional downstream Bragg reflectors and driven by two parallel-sheet electron beams 0.8 MeV /1 kA has been elaborated. For the highly oversized interaction space (cross section 45 ×2.5 vacuum wavelengths), the two-dimensional distributed feedback allowed realization of stable narrow-band generation that includes synchronization of emission from both electron beams. As a result, spatially coherent radiation with the output power of 30-50 MW and a pulse duration of ˜100 ns was obtained in each channel.

  17. Constraints on the pMSSM, AMSB model and on other models from the search for long-lived charged particles in proton-proton collisions at √s = 8 TeV

    SciTech Connect

    Khachatryan, Vardan

    2015-07-17

    Stringent limits are set on the long-lived lepton-like sector of the phenomenological minimal supersymmetric standard model (pMSSM) and the anomaly-mediated supersymmetry breaking (AMSB) model. We derived the limits from the results presented in a recent search for long-lived charged particles in proton–proton collisions, based on data collected by the CMS detector at a centre-of-mass energy of 8 TeV at the Large Hadron Collider. In the pMSSM parameter sub-space considered, 95.9 % of the points predicting charginos with a lifetime of at least 10 ns are excluded. Furthermore, these constraints on the pMSSM are the first obtained at the LHC. Charginos with a lifetime greater than 100 ns and masses up to about 800 GeV in the AMSB model are also excluded. Furthermore, the method described can also be used to set constraints on other models.

  18. Progress on a New Non-Volatile Memory for Space Based on Chalcogenide Glass

    SciTech Connect

    Maimon, J.; Hunt, K.; Rodgers, J.; Burcin, L.; Knowles, K.

    2004-02-04

    We report on the progress of a recent addition to non-volatile solid state memory technologies suited for space and other ionizing radiation environments. We summarize the material and processing science behind the current generation of chalcogenide phase-change memories fabricated on CMOS structures. The chalcogenide material used for phase-change applications in rewritable optical storage (Ge2Sb2Te5) has been integrated with a radiation hardened CMOS process to produce 64kbit memory arrays. On selected arrays electrical testing demonstrated up to 100% memory cell yield, 100ns programming and read speeds, and write currents as low as 1mA/bit. Devices functioned normally from - 55 deg. C to 125 deg. C. Write/read endurance has been demonstrated to 1 x 108 before first bit failure. Radiation results show no degradation to the hardened CMOS or effects that can be attributed to the phase-change material. Future applications of the technology are discussed.

  19. Pulsar timing sensitivity to very-low-frequency gravitational waves

    SciTech Connect

    Jenet, Fredrick A.; Armstrong, J. W.; Tinto, Massimo

    2011-04-15

    We compute the sensitivity, constrained by instrumental, propagation, and other fundamental noises, of pulsar timing to very-low-frequency gravitational waves (GWs). Reaching predicted GW signal strengths will require suppression of time-of-arrival fluctuations caused by interstellar plasma turbulence and a reduction of white rms timing noise to < or approx. 100 ns. Assuming negligible intrinsic pulsar rotational noise, perfect time transfer from time standard to observatory, and stable pulse profiles, the resulting single-pulsar signal-to-noise ratio=1 sensitivity is limited by terrestrial time standards at h{sub rms}{approx}2x10{sup -16} [f/ (1 cycle/year)]-1/2 for f<3x10{sup -8} Hz, where f is the Fourier frequency and a bandwidth of 1 cycle/(10 years) is assumed. Since this sensitivity is comparable to predicted GW signal levels, a reliable detection will require substantial signal-to-noise ratio improvement via pulsar timing array.

  20. A distributed optical fiber sensing system for synchronous vibration and loss measurement

    NASA Astrophysics Data System (ADS)

    Zhang, Xu-ping; Qiao, Wei-yan; Sun, Zhen-hong; Shan, Yuan-yuan; Zeng, Jie; Zhang, Yi-xin

    2016-09-01

    We propose a fully distributed fusion system combining phase-sensitive optical time-domain reflectometry (Φ-OTDR) and OTDR for synchronous vibration and loss measurement by setting an ingenious frequency sweep rate ( FSR) of the optical source. The relationships between FSR, probe pulse width and repeat period are given to balance the amplitude fluctuation of OTDR traces, the dead zone probability and the measurable frequency range of vibration events. In the experiment, we achieve synchronous vibration and loss measurement with FSR of 40 MHz/s, the proble pulse width of 100 ns and repeat rate of 0.4 ms. The fluctuation of OTDR trace is less than 0.45 dB when the signal-to-noise ratio ( SNR) is over 12 dB for a captured vibration event located at 9.1 km. The proposed method can be used for not only detection but also early warning of damage events in optical communication networks.

  1. Effects of picosecond terawatt UV laser beam filamentation and a repetitive pulse train on creation of prolonged plasma channels in atmospheric air

    NASA Astrophysics Data System (ADS)

    Zvorykin, V. D.; Ionin, A. A.; Levchenko, A. O.; Seleznev, L. V.; Shutov, A. V.; Sinitsyn, D. V.; Smetanin, I. V.; Ustinovskii, N. N.

    2013-08-01

    Amplitude-modulated UV laser pulse of up to 30 J energy was produced at hybrid Ti:Sapphire/KrF GARPUN-MTW laser facility when a preliminary amplified train of short pulses was injected into unstable resonator cavity of the main e-beam-pumped KrF amplifier. The combined radiation consisted of regeneratively amplified picosecond pulses with subTW peak power overlapped with 100-ns pulse of a free-running lasing. The advantages of combined radiation for production of long-lived prolonged plasma channels in air and HV discharge triggering were demonstrated: photocurrent sustained by modulated pulse is two orders of magnitude higher and HV breakdown distance is twice longer than for a smooth UV pulse. It was found that in contrast to IR radiation multiple filamentation of high-power UV laser beam does not produce extended nonlinear focusing of UV radiation.

  2. 1.95  μm-pumped OP-GaAs optical parametric oscillator with 10.6  μm idler wavelength.

    PubMed

    Wueppen, Jochen; Nyga, Sebastian; Jungbluth, Bernd; Hoffmann, Dieter

    2016-09-15

    We report on an optical parametric oscillator that generates output idler wavelengths around 10.6 μm. On the basis of orientation-patterned gallium arsenide (OP-GaAs) as a nonlinear medium and a 1.95 μm ns-pulsed pump laser, a signal-resonant bow-tie resonator was designed in order to maximize the output power at moderate intensities well below the damage threshold of the optical components. With this setup, the average idler output power at 50 kHz and 100 ns idler pulse length was more than 800 mW, which corresponds to a pulse energy of 16 μJ. The maximum quantum conversion efficiency of 36.8% is the highest value measured so far for comparable setups to the best of our knowledge.

  3. The S-193 radar altimeter experiment. [onboard Skylab for earth surface profile measurement

    NASA Technical Reports Server (NTRS)

    Mcgoogan, J. T.; Miller, L. S.; Brown, G. S.; Hayne, G. S.

    1974-01-01

    The Skylab S-193 altimeter experiment utilizes a 10- and 100-ns pulse length, 13.9-GHz earth-pointed radar system to obtain earth-surface backscatter measurements from the Skylab spacecraft. Objectives of the experiment are to obtain precision measurements of surface profile for uses in geodesy, oceanography, and earth physics, and to measure radar-signal characteristics from an earth-orbit geometry to provide design information for future radar remote-sensors. The technical approach is that of measuring the power impulse response of the scattering surface. The hardware is designed to operate in five modes: waveform or impulse-response measurement and altitude determination; radar cross-section experiment; signal correlation experiment; 10-nsec pulse-compression evaluation; and nadir-seeker experiment.

  4. A distributed, graphical user interface based, computer control system for atomic physics experiments

    NASA Astrophysics Data System (ADS)

    Keshet, Aviv; Ketterle, Wolfgang

    2013-01-01

    Atomic physics experiments often require a complex sequence of precisely timed computer controlled events. This paper describes a distributed graphical user interface-based control system designed with such experiments in mind, which makes use of off-the-shelf output hardware from National Instruments. The software makes use of a client-server separation between a user interface for sequence design and a set of output hardware servers. Output hardware servers are designed to use standard National Instruments output cards, but the client-server nature should allow this to be extended to other output hardware. Output sequences running on multiple servers and output cards can be synchronized using a shared clock. By using a field programmable gate array-generated variable frequency clock, redundant buffers can be dramatically shortened, and a time resolution of 100 ns achieved over effectively arbitrary sequence lengths.

  5. Time-Resolved High-Spatial-Resolution Measurements of Underwater Laser Ionization and Filamentation

    NASA Astrophysics Data System (ADS)

    Jones, T. G.; Kaganovich, D.; Helle, M. H.; Penano, J.; Ting, A.; Gordon, D.

    2013-10-01

    Laser triggering and guiding of underwater electrical discharges are being investigated and developed at NRL for applications including advanced micromachining and low-frequency laser acoustic generation. As part of this development we recently made several high-spatial-resolution, time-resolved measurements of underwater optical filamentation and laser ionization. Using 2-laser pump-probe backlit imaging techniques, we were able to achieve time resolution as short as 35 fs and spatial resolution down to 1 micron. Shadowgraph images show few-micron diameter gas bubbles forming throughout the pump beam path in ps timescales. Microbubble numbers and density increased with pulse energy and time during the pump pulse. We also obtained time-resolved spectra of ns-laser-ionized water, revealing black-body radiation lasting more than 100 ns after the ionizing pulse. Results from ongoing underwater laser ionization, filamentation, and discharge-guiding experiments will be presented. This work is supported by NRL Base Funds.

  6. Accelerator power concepts using isolated transmission lines

    SciTech Connect

    Nunnally, W.C.

    1981-05-01

    This report outlines the rationale and the advantages of using multiple transmission-line sections isolated by transit time and inductance in accelerating high-current (approx. = 10 -kA), short-pulse (less than or equal to 100-ns) particle beams to the multimegavolt level. The main advantages of this system include reducing the number of output switches required per output pulse by nearly an order of magnitude over conventional systems and increasing the system capability for repetition-rate operation. The isolated transmission-line concept is developed, and possible modes of operation are outlined. In addition, a point design of a 10-kA short-pulse accelerator is presented.

  7. Compact 810 kA Linear Transformer Driver Cavity

    NASA Astrophysics Data System (ADS)

    Woodworth, J. R.; Fowler, W. E.; Stoltzfus, B. S.; Stygar, W. A.; Sceiford, M. E.; Mazarakis, M. G.; Anderson, H. D.; Harden, M. J.; Blickem, J. R.; White, R.; Kim, A. A.

    2011-04-01

    We are performing experiments with a 92-kV, 810-kA, 74.6-GW linear transformer driver (LTD) cavity. This cavity generates a ˜100ns power pulse from DC-charged capacitors in a single step. Our experiments start with an existing 100-kV, 490-kA LTD cavity and are making a number of improvements to it that are aimed at increasing the cavity’s peak output power and better understanding its operation. We are making improvements to the gas switches, the capacitors, and the magnetic toroids as well as heavily instrumenting the cavity. These experiments have increased the cavity’s output current into a matched load by 65% without increasing its volume.

  8. Gradient ascent pulse engineering approach to CNOT gates in donor electron spin quantum computing

    SciTech Connect

    Tsai, D.-B.; Goan, H.-S.

    2008-11-07

    In this paper, we demonstrate how gradient ascent pulse engineering (GRAPE) optimal control methods can be implemented on donor electron spin qubits in semiconductors with an architecture complementary to the original Kane's proposal. We focus on the high fidelity controlled-NOT (CNOT) gate and we explicitly find the digitized control sequences for a controlled-NOT gate by optimizing its fidelity using the effective, reduced donor electron spin Hamiltonian with external controls over the hyperfine A and exchange J interactions. We then simulate the CNOT-gate sequence with the full spin Hamiltonian and find that it has an error of 10{sup -6} that is below the error threshold of 10{sup -4} required for fault-tolerant quantum computation. Also the CNOT gate operation time of 100 ns is 3 times faster than 297 ns of the proposed global control scheme.

  9. Kinetic energy spectra in thermionic emission from small tungsten cluster anions: evidence for nonclassical electron capture.

    PubMed

    Concina, Bruno; Baguenard, Bruno; Calvo, Florent; Bordas, Christian

    2010-03-14

    The delayed electron emission from small mass-selected anionic tungsten clusters W(n)(-) has been studied for sizes in the range 9 < or = n < or = 21. Kinetic energy spectra have been measured for delays of about 100 ns after laser excitation by a velocity-map imaging spectrometer. They are analyzed in the framework of microreversible statistical theories. The low-energy behavior shows some significant deviations with respect to the classical Langevin capture model, which we interpret as possibly due to the influence of quantum dynamical effects such as tunneling through the centrifugal barrier, rather than shape effects. The cluster temperature has been extracted from both the experimental kinetic energy spectrum and the absolute decay rate. Discrepancies between the two approaches suggest that the sticking probability can be as low as a few percent for the smallest clusters.

  10. Potential enhancement of warm x-ray dose from a reflexing bremsstrahlung diode

    SciTech Connect

    Sanford, T.W.L.; Halbleib, J.A.; Cooperstein, G.; Weber, B.V.

    1995-07-01

    The potential for generating intense bursts of war x rays (20 to 60 keV) using electron reflexing diodes on pulsed-power accelerators is evaluated with the TIGER Monte Carlo code, showing that hundreds of kilojoules of warm x rays can be generated under idealized conditions. The calculation are compared with data from Gamble-II experiments and applied to two suggest Jupiter (60-MA, 5-MV, 100-ns) diode configurations. If the simultaneous irradiation from the high-energy tail of the bremsstrahlung which accompanies the warm x rays is a concern, then the reflexing technique is shown to be limited to the irradiation of targets thinner than {approximately} 400 {mu}m for low-Z targets like aluminum and thinner than {approximately} 5 {mu}m for high-Z targets like gold.

  11. Potential enhancement of warm X-ray dose from a reflexing bremsstrahlung diode

    SciTech Connect

    Sanford, T.W.L.; Halbleib, J.A.; Cooperstein, G.

    1995-08-01

    The potential for generating intense bursts of warm x rays (20 to 60 keV) using electron reflexing diodes on pulsed-power accelerators is evaluated with the TIGER Monte Carlo code, showing that hundreds of kilojoules of warm x rays can be generated under idealized conditions, for a Jupiter (60-MA, 5-MV, 100-ns) class accelerator. The calculations are compared with data from Gamble-II experiments and applied to two suggested Jupiter diode configurations. If the simultaneous irradiation from the high-energy tail of the bremsstrahlung, which accompanies the warm x rays, is a concern then the reflexing technique is shown to be limited to the irradiation of targets thinner than {approximately}400 {mu}m for low-Z targets like aluminum and thinner than {approximately}5 {mu}m for high-Z targets like gold.

  12. Soft X-Ray Measurements of Z-Pinch-Driven Vacuum Hohlraums

    SciTech Connect

    Baker, K.L.; Porter, J.L.; Ruggles, L.E.; Chandler, G.A.; Deeney, Chris; Varas, M.; Moats, Ann; Struve, Ken; Torres, J.; McGurn, J.; Simpson, W.W.; Fehl, D.L.; Chrien, R.E.; Matuska, W.; Idzorek, G.C.

    1999-07-21

    This article reports the experimental characterization of a z-pinch driven-vacuum hohlraum. The authors have measured soft x-ray fluxes of 5 x 10{sup 12} W/cm{sup 2} radiating from the walls of hohlraums which are 2.4--2.5 cm in diameter by 1 cm tall. The x-ray source used to drive these hohlraums was a z-pinch consisting of a 300 wire tungsten array driven by a 2 MA, 100 ns current pulse. In this hohlraum geometry, the z-pinch x-ray source can produce energies in excess of 800 kJ and powers in excess of 100 TW to drive these hohlraums. The x-rays released in these hohlraums represent greater than a factor of 25 in energy and more than a factor of three in x-ray power over previous laboratory-driven hohlraums.

  13. Shock induced phase transition of water: Molecular dynamics investigation

    NASA Astrophysics Data System (ADS)

    Neogi, Anupam; Mitra, Nilanjan

    2016-02-01

    Molecular dynamics simulations were carried out using numerous force potentials to investigate the shock induced phenomenon of pure bulk liquid water. Partial phase transition was observed at single shock velocity of 4.0 km/s without requirement of any external nucleators. Change in thermodynamic variables along with radial distribution function plots and spectral analysis revealed for the first time in the literature, within the context of molecular dynamic simulations, the thermodynamic pathway leading to formation of ice VII from liquid water on shock loading. The study also revealed information for the first time in the literature about the statistical time-frame after passage of shock in which ice VII formation can be observed and variations in degree of crystallinity of the sample over the entire simulation time of 100 ns.

  14. Circuit model for the inverse Z-pinch wire array switch.

    SciTech Connect

    Waisman, Eduardo Mario; Cuneo, Michael Edward; Harvey-Thompson, A.; Lebedev, Sergey V.

    2010-06-01

    A 0D circuit code is introduced to study the wire array switch concept introduced in. It has been implemented and researched at Imperial College. An exploding wire array, the switch, is in parallel with the load, an imploding wire array. Most of the current flows in the exploding array until it expands and becomes highly resistive. The 0D code contains simple models of Joule energy deposition and plasma expansion for W and Al wires. The purpose of the device is to produce fast Z-pinch implosion, below 100ns on MAGPIE and the Sandia Z machine. Self and mutual inductances are taken into consideration as well as the rocket model for wire ablation. The switch characteristics of the exploding array are prescribed and tuned up to agree with MAGPIE shots. The dependence of the device on the configuration of the arrays is studied and scaling to ZR conditions is explored.

  15. Experimental investigation of silicon photomultipliers as compact light readout systems for gamma-ray spectroscopy applications in fusion plasmas

    SciTech Connect

    Nocente, M. Gorini, G.; Fazzi, A.; Lorenzoli, M.; Pirovano, C.; Tardocchi, M.; Cazzaniga, C.; Rebai, M.; Uboldi, C.; Varoli, V.

    2014-11-15

    A matrix of Silicon Photo Multipliers has been developed for light readout from a large area 1 in. × 1 in. LaBr{sub 3} crystal. The system has been characterized in the laboratory and its performance compared to that of a conventional photo multiplier tube. A pulse duration of 100 ns was achieved, which opens up to spectroscopy applications at high counting rates. The energy resolution measured using radioactive sources extrapolates to 3%–4% in the energy range E{sub γ} = 3–5 MeV, enabling gamma-ray spectroscopy measurements at good energy resolution. The results reported here are of relevance in view of the development of compact gamma-ray detectors with spectroscopy capabilities, such as an enhanced gamma-ray camera for high power fusion plasmas, where the use of photomultiplier is impeded by space limitation and sensitivity to magnetic fields.

  16. Crank-angle resolved imaging of biacetyl laser-induced fluorescence in an optical internal combustion engine

    NASA Astrophysics Data System (ADS)

    Smith, J. D.; Sick, V.

    2005-09-01

    The use of a frequency-tripled, diode-pumped Nd:YAG laser in combination with a CMOS camera lens-coupled to a three-stage image intensifier allowed the visualization of the fuel distribution with crank angle resolution for hundreds of consecutive engine cycles. Biacetyl, doped into iso-octane, was excited at rates of 12 kHz with 100 ns pulses. Pulse energies are high enough to allow single-pulse imaging of the vapor-phase fuel distribution for motored and fired operation in an optical engine. The repetition rate of the setup is adequate to resolve critical steps in the development of the fuel cloud around the spark plug of a direct-injection gasoline engine.

  17. Pulsed discharge production Ar* metastables

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  18. Study of nanosecond laser-produced plasmas in atmosphere by spatially resolved optical emission spectroscopy

    SciTech Connect

    Wei, Wenfu; Wu, Jian; Li, Xingwen; Jia, Shenli; Qiu, Aici

    2013-09-21

    We investigate the evolution of the species from both the target and the air, and the plasma parameter distribution of the nanosecond laser-produced plasmas in atmospheric air. The technique used is spatially resolved optical emission spectroscopy. It is argued that the N II from the air, which is distributed over a wider region than the target species in the early stages of the discharge, is primarily formed by the shock wave. The ionized species have a larger expansion velocity than the excited atoms in the first ∼100 ns, providing direct evidence for space-charge effects. The electron density decreases with the distance from the target surface in the early stages of the discharge, and both the electron density and the excited temperature variation in the axial direction are found to become insignificant at later stages.

  19. Parametric scaling study of a magnetically insulated thermionic vacuum switch

    SciTech Connect

    Vanderberg, B.H.; Eninger, J.E.

    1996-02-01

    A parametric scaling study is performed on MINOS (Magnetically INsulated Opening Switch), a novel fast ({approximately}100 ns) high-power opening switch concept based on a magnetically insulated thermionic vacuum diode. Principal scaling parameters are the switch dimensions, voltage, current, applied magnetic field, and switching time. The scaling range of interest covers voltages up to 100 kV and currents of several kA. Fundamental scaling properties are derived from models of space-charge flow and magnetic cutoff. The scaling is completed with empirical results from the experimental MX-1 switch operated in an inductive storage pulsed power generator. Results are presented in diagrams showing voltage, current, power, and efficiency relationships and their limitations. The scaling is illustrated by the design of a megawatt average power opening switch for pulsed power applications. Trade-offs in the engineering of this type of switch are discussed.

  20. Fast nanoscale addressability of nitrogen-vacancy spins via coupling to a dynamic ferromagnetic vortex

    DOE PAGES

    Wolf, M. S.; Badea, R.; Berezovsky, J.

    2016-06-14

    The core of a ferromagnetic vortex domain creates a strong, localized magnetic field, which can be manipulated on nanosecond timescales, providing a platform for addressing and controlling individual nitrogen-vacancy centre spins in diamond at room temperature, with nanometre-scale resolution. Here, we show that the ferromagnetic vortex can be driven into proximity with a nitrogen-vacancy defect using small applied magnetic fields, inducing significant nitrogen-vacancy spin splitting. We also find that the magnetic field gradient produced by the vortex is sufficient to address spins separated by nanometre-length scales. By applying a microwave-frequency magnetic field, we drive both the vortex and the nitrogen-vacancymore » spins, resulting in enhanced coherent rotation of the spin state. Lastly, we demonstrate that by driving the vortex on fast timescales, sequential addressing and coherent manipulation of spins is possible on ~ 100 ns timescales.« less

  1. Coherent control of ultracold {sup 85}Rb trap-loss collisions with nonlinearly frequency-chirped light

    SciTech Connect

    Pechkis, J. A.; Carini, J. L.; Rogers, C. E. III; Gould, P. L.; Kallush, S.; Kosloff, R.

    2011-06-15

    We present results on coherent control of ultracold trap-loss collisions using 40-ns pulses of nonlinearly frequency-chirped light. The chirps, either positive or negative, sweep {approx}1 GHz in 100 ns and are centered at various detunings below the D{sub 2} line of {sup 85}Rb. At each center detuning, we compare the collisional rate constant {beta} for chirps that are linear in time, concave-down, and concave-up. For positive chirps, we find that {beta} generally depends very little on the shape of the chirp. For negative chirps, however, we find that {beta} can be enhanced by up to 50(20)% for the case of the concave-down shape. This occurs at detunings where the evolution of the wave packet is expected to be coherent. An enhancement at these detunings is also seen in quantum-mechanical simulations of the collisional process.

  2. Photon correlation studies of charge variation in a single GaAlAs quantum dot

    NASA Astrophysics Data System (ADS)

    Piętka, B.; Suffczyński, J.; Goryca, M.; Kazimierczuk, T.; Golnik, A.; Kossacki, P.; Wysmolek, A.; Gaj, J. A.; Stępniewski, R.; Potemski, M.

    2013-01-01

    Complex charge variation processes in low-density, direct-type GaAlAs quantum dots embedded in a type-II GaAs/AlAs bilayer are studied by single-photon correlation measurements. Two groups of excitonic transitions are distinguished in the single quantum dot (QD) photoluminescence spectra, namely due to recombination of neutral and charged multiexcitonic complexes. The radiative cascades are found within each group. Three characteristic time scales are identified in the QD emission dynamics. The fastest one (of the order of 1 ns) is related to excitonic radiative recombination. The two remaining ones are related to the QD charge state variation. The one of 100-ns range (typical blinking time scale) corresponds to random capture of single carriers under a quasiresonant excitation. The slowest processes, in the range of seconds, are related to charge fluctuations in the surrounding of the dot.

  3. System Radiographic Characterization of 7MV Self-Magnetic Pinch Diode on RITS-6

    NASA Astrophysics Data System (ADS)

    Webb, Tim J.; Johnston, Mark D.; Oliver, Bryan V.

    2011-10-01

    The 7 MV, 160 kA induction voltage adder RITS-6 is used as a test bed for research and development of sub-100 ns flash x-ray radiography of which the self-magnetic pinch (SMP) diode is an example. The x-ray source properties such as dose, source spatial distribution, and energy spectrum couple with the imaging detector sensitivity and blur to form the radiologic system performance which is also highly dependent on the imaging geometry. The system performance of some SMP diode configurations will be presented. Sandia is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  4. Directly diode-pumped high-energy Ho:YAG oscillator.

    PubMed

    Lamrini, Samir; Koopmann, Philipp; Schäfer, Michael; Scholle, Karsten; Fuhrberg, Peter

    2012-02-15

    We report on the high-energy laser operation of an Ho:YAG oscillator resonantly pumped by a GaSb-based laser diode stack at 1.9 μm. The output energy was extracted from a compact plano-concave acousto-optically Q-switched resonator optimized for low repetition rates. Operating at 100 Hz, pulse energies exceeding 30 mJ at a wavelength of 2.09 μm were obtained. The corresponding pulse duration at the highest pump power was 100 ns, leading to a maximum peak power above 300 kW. Different pulse repetition rates and output coupling transmissions of the Ho:YAG resonator were studied. In addition, intracavity laser-induced damage threshold measurements are discussed.

  5. Alternative method for gas detection using pulsed quantum-cascade-laser spectrometers.

    PubMed

    Grouiez, Bruno; Parvitte, Bertrand; Joly, Lilian; Zeninari, Virginie

    2009-01-15

    Pulsed quantum-cascade-laser (QCL) spectrometers are usually used to detect atmospheric gases with either the interpulse technique (short pulses, typically 5-20 ns) or the intrapulse technique (long pulses, typically 500-800 ns). Each of these techniques has many drawbacks, which we present. Particularly the gas absorption spectra are generally distorted. We demonstrate the possibility to use intermediate pulses (typically 50-100 ns) for gas detection using pulsed QCL spectrometers. IR spectra of ammonia recorded in the 10 microm region are presented in various conditions of pulse emission. These experiences demonstrate the large influence of the pulse shape on the recorded spectrum and the importance to use our alternative method for gas detection with pulsed QCL spectrometers.

  6. Tunable repetitively pulsed Cr{sup 2+} : ZnSe laser

    SciTech Connect

    Egorov, A S; Eremeikin, O N; Pavlenko, K Yu; Savikin, A P; Sharkov, V V

    2012-12-31

    Methods of wavelength tuning of a polycrystalline Cr{sup 2+} : ZnSe laser pumped by a repetitively pulsed Tm : YLF laser (pulse duration {approx}100 ns, pulse repetition rate 3 KHz) are studied. With the use of a prism selector, the laser wavelength was tuned within the range of 2070 - 2400 nm at a linewidth of 11 nm for a SiO{sub 2} prism and 30 nm for a CaF{sub 2} prism. The use of a Lyot filter made it possible to tune the Cr{sup 2+} : ZnSe laser wavelength (with replacement of the cavity mirrors) within the spectral ranges of 2130 - 2400 and 2530 - 2750 nm at a linewidth of 4 nm. (lasers)

  7. Continuous-wave and Q-switched operation of a resonantly pumped Ho³⁺:KY₃F₁₀ laser.

    PubMed

    Schellhorn, Martin; Parisi, Daniela; Eichhorn, Marc; Tonelli, Mauro

    2014-03-01

    We report continuous-wave and repetitively Q-switched operation of a resonantly pumped Ho3+:KY3F10 laser at room temperature. End pumped by a Tm3+-doped silica fiber laser operating at 1938 nm, a maximum laser power of 7.8 W was obtained at a wavelength of ∼2041  nm for 21 W of absorbed pump power, corresponding to a slope efficiency of 60.7% with respect to absorbed power. At a repetition rate of 10 kHz up to 0.78 mJ, energy per pulse was demonstrated with pulse widths of 100 ns. The beam propagation factor (M2) was measured to be <1.26 at the maximum output power.

  8. Understanding the molecular basis of substrate binding specificity of PTB domains

    PubMed Central

    Sain, Neetu; Tiwari, Garima; Mohanty, Debasisa

    2016-01-01

    Protein-protein interactions mediated by phosphotyrosine binding (PTB) domains play a crucial role in various cellular processes. In order to understand the structural basis of substrate recognition by PTB domains, multiple explicit solvent atomistic simulations of 100ns duration have been carried out on 6 PTB-peptide complexes with known binding affinities. MM/PBSA binding energy values calculated from these MD trajectories and residue based statistical pair potential score show good correlation with the experimental dissociation constants. Our analysis also shows that the modeled structures of PTB domains can be used to develop less compute intensive residue level statistical pair potential based approaches for predicting interaction partners of PTB domains. PMID:27526776

  9. Continuum model of tensile fracture of metal melts and its application to a problem of high-current electron irradiation of metals

    SciTech Connect

    Mayer, Alexander E. E-mail: mayer.al.evg@gmail.com; Mayer, Polina N.

    2015-07-21

    A continuum model of the metal melt fracture is formulated on the basis of the continuum mechanics and theory of metastable liquid. A character of temperature and strain rate dependences of the tensile strength that is predicted by the continuum model is verified, and parameters of the model are fitted with the use of the results of the molecular dynamics simulations for ultra-high strain rates (≥1–10/ns). A comparison with experimental data from literature is also presented for Al and Ni melts. Using the continuum model, the dynamic tensile strength of initially uniform melts of Al, Cu, Ni, Fe, Ti, and Pb within a wide range of strain rates (from 1–10/ms to 100/ns) and temperatures (from melting temperature up to 70–80% of critical temperature) is calculated. The model is applied to numerical investigation of a problem of the high-current electron irradiation of Al, Cu, and Fe targets.

  10. Time-of-flight neutral particle analyzer and calibration.

    PubMed

    Harris, W S; Garate, E P; Heidbrink, W W; McWilliams, R; Roche, T; Trask, E; Zhang, Yang

    2008-10-01

    A time-of-flight diagnostic has been implemented on the Irvine field reversed configuration (IFRC) to obtain an energy distribution function from charge-exchanged neutral hydrogen. The diagnostic includes a 13 cm radius slotted disk rotating at 165 Hz in vacuum which chops the emitted neutrals at a rate of 26 kHz. In situ timing verification was performed with a dc xenon discharge lamp with an uncertainty less than 100 ns for a 38 micros chopping period. Energy calibration was accomplished with a singly ionized lithium source in the range of 300-1500 eV, achieving an average energy uncertainty, DeltaE/E, of 0.11. The diagnostic has measured neutrals in the range of 20-80 eV from the IFRC and the corresponding energy distribution function has been obtained.

  11. Time-of-flight neutral particle analyzer and calibration

    SciTech Connect

    Harris, W. S.; Garate, E. P.; Heidbrink, W. W.; McWilliams, R.; Roche, T.; Trask, E.; Zhang Yang

    2008-10-15

    A time-of-flight diagnostic has been implemented on the Irvine field reversed configuration (IFRC) to obtain an energy distribution function from charge-exchanged neutral hydrogen. The diagnostic includes a 13 cm radius slotted disk rotating at 165 Hz in vacuum which chops the emitted neutrals at a rate of 26 kHz. In situ timing verification was performed with a dc xenon discharge lamp with an uncertainty less than 100 ns for a 38 {mu}s chopping period. Energy calibration was accomplished with a singly ionized lithium source in the range of 300-1500 eV, achieving an average energy uncertainty, {delta}E/E, of 0.11. The diagnostic has measured neutrals in the range of 20-80 eV from the IFRC and the corresponding energy distribution function has been obtained.

  12. Preliminary results of Linear Induction Accelerator LIA-200

    NASA Astrophysics Data System (ADS)

    Sharma, Archana; Senthil, K.; Praveen Kumar, D. D.; Mitra, S.; Sharma, V.; Patel, A.; Sharma, D. K.; Rehim, R.; Kolge, T. S.; Saroj, P. C.; Acharya, S.; Amitava, Roy; Rakhee, M.; Nagesh, K. V.; Chakravarthy, D. P.

    2010-05-01

    Repetitive Pulsed Power Technology is being developed keeping in mind the potential applications of this technology in material modifications, disinfections of water, timber, and food pasteurization etc. BARC has indigenously developed a Linear Induction Accelerator (LIA-200) rated for 200 kV, 4 kA, 100 ns, 10 Hz. The satisfactory performance of all the sub-systems including solid state power modulator, amorphous core based pulsed transformers, magnetic switches, water capacitors, water pulse- forming line, induction adder and field-emission diode have been demonstrated. This paper presents some design details and operational results of this pulsed power system. It also highlights the need for further research and development to build reliable and economic high-average power systems for industrial applications.

  13. Density and temperature scaling of disorder-induced heating in ultracold plasmas

    SciTech Connect

    Bergeson, S. D.; Denning, A.; Lyon, M.; Robicheaux, F.

    2011-02-15

    We report measurements and simulations of disorder-induced heating in ultracold neutral plasmas. Fluorescence from plasma ions is excited using a detuned probe laser beam while the plasma relaxes from its initially disordered nonequilibrium state. This method probes the wings of the ion velocity distribution. The simulations yield information on time-evolving plasma parameters that are difficult to measure directly and make it possible to connect the fluorescence signal to the rms velocity distribution. The disorder-induced heating signal can be used to estimate the electron and ion temperatures {approx}100 ns after the plasma is created. This is particularly interesting for plasmas in which the electron and ion temperatures are not known.

  14. Electron Optics Design and Performance of a New Large-Format Two-Frame Framing Tube

    SciTech Connect

    Lai, C C

    2002-11-08

    We have developed a framing tube with 80-mm photocathode for capturing two frames in less than 100-ns onto a 50-mm phosphor screen. A proven electron optics trajectory code was used to design the tube for imaging fidelity over wide dynamic range. This code's full accounting of space charge effects is essential for its ability to simulate accurately the distributed photoelectronic trajectories from the entire large photocathode area. Our approach and guideline for designing the electron optics are described. Results of trajectory simulation and test measurement are reported. Substantial correlations between the code expectation and the measured results are observed on relative resolution and distortion of the frame images. This tube has been integrated into an active framing camera system for field application.

  15. The development and test of multi-anode microchannel array detector systems. Part 2: Soft X-ray detectors

    NASA Technical Reports Server (NTRS)

    Timothy, J. G.

    1986-01-01

    Detector systems based on the high gain microchannel plate (MCP) electron multiplier were used extensively for imaging at soft X-ray wavelengths both on the ground and in space. The latest pulse counting electronic readout systems provide zero readout noise, spatial resolutions (FWHM) of 25 microns or better and can determine the arrival times of detected photons to an accuracy of the order of 100 ns. These systems can be developed to produce detectors with active areas of 100 nm in diameter or greater. The use of CsI photocathodes produces very high detective quantum efficiencies at wavelengths between about 100 and 1A (approximately 0.1 to 10 keV) with moderate energy resolution. The operating characteristics of the different types of soft X-ray MCP detector systems are described and the prospects for future developments are discussed.

  16. Thermal lens measurements in liquids on a submicrosecond time scale

    SciTech Connect

    Isak, S. J.; Komorowski, S. J.; Merrow, C. N.; Poston, P. E.; Eyring, E. M.

    1989-03-01

    The use of the thermal lens method is shown to be quite suitable for kinetic studies of quenching on a submicrosecond time scale. The lower limit of time resolution that can be achieved is determined by the acoustic transit time, /tau//sub /ital a//, in the medium. A thermal lens signal with a 100-ns time constant due to the quenched triplet state of benzophenone is readily measured. The thermal lens method is superior to the photoacoustic (PA) method in the breadth of the accessible time range, and in the significantly fewer measurements required to obtain accurate data, including no requirement for a reference sample; it is also less sensitive to geometrical and laser power requirements than is the PA method.

  17. Fast turn-off of high voltage 4H-SiC npn BJTs from the saturation on-state regime

    NASA Astrophysics Data System (ADS)

    Ivanov, P. A.; Levinshtein, M. E.; Palmour, J. W.; Agarwal, A. K.; Zhang, J.

    2010-04-01

    Fast turn-off of high-voltage (breakdown voltage >= 3 kV) 4H-SiC npn bipolar junction transistors driven in a deeply saturated regime has been reported. In the conventional turn-off mode (base current break), the turn-off delay and current fall times are 80 ns and 100 ns, respectively. It is shown that these times can be made as short as 20 and 4 ns, respectively, if a reverse base current pulse of appropriate amplitude is applied to sweep out minority carriers from the base. The experimental values of delay and turn-off times well coincide with those calculated in terms of the charge control model.

  18. PRINCIPLE DESIGN OF 300KHZ MECO RF KICKER BIPOLAR SOLID STATE MODULATOR.

    SciTech Connect

    ZHANG,W.; KOTLYAR,Y.

    2004-05-23

    A high speed, high repetition rate, bipolar solid-state high voltage modulator is under development at Brookhaven National Laboratory for Muon Electron Conversion (MECO) Experiment. The modulator will be used to drive a RF kicker consisting a pair of parallel deflecting plates. The principle design is based on the inductive-adder topology. This system requires a fast pulse rise and fall time about 20ns, a pulse width of 100ns, a pulse repetition rate of 300 kHz, and a 60 kHz sine-wave amplitude modulation. The fast high voltage MOSFETs are used as main switching devices.Different magnetic materials are being investigated for adder core magnets. The main circuit design, critical subsystems, and major technical issues will be discussed. The circuit simulation, components selection and evaluation, and preliminary test results will be presented.

  19. 600 kV modulator design for the SLAC Next Linear Collider Test Accelerator

    SciTech Connect

    Harris, K.; de Lamare, J.; Nesterov, V.; Cassel, R.

    1992-07-01

    Preliminary design for the SLAC Next Linear Collider Test Accelerator (NLCTA) requires a pulse power source to produce a 600 kV, 600 A, 1.4 {mu}s, 0.1% flat top pulse with rise and fall times of approximately 100 ns to power an X-Band klystron with a microperveance of 1.25 at {approx} 100 MW peak RF power. The design goals for the modulator, including those previously listed, are peak modulator pulse power of 340 MW operating at 120 Hz. A three-stage darlington pulse-forming network, which produces a >100 kV, 1.4 {mu}s pulse, is coupled to the klystron load through a 6:1 pulse transformer. Careful consideration of the transformer leakage inductance, klystron capacitance, system layout, and component choice is necessary to produce the very fast rise and fall times at 600 kV operating continuously at 120 Hz.

  20. Determining the energy balance in barrier-discharge Xe2 excilamp by the pressure jump method

    NASA Astrophysics Data System (ADS)

    Sosnin, E. A.; Panarin, V. A.; Skakun, V. S.; Pikulev, A. A.; Tarasenko, V. F.

    2016-08-01

    The energy redistribution in barrier-discharge Xe2 excilamp in various excitation regimes is investigated using the pressure jump method. Analytic expressions are derived for calculating power W dissipated in the excilamp discharge plasma in the form of heat and for calculating total discharge heat power P T spent on heating the excilamp. It is shown that the mechanism of the thermal energy dissipation gradually changes upon an increase in the xenon pressure in the excilamp. The conditions for generating the maximal radiation power of the excilamp are determined. It is shown that the maximum of the average radiation power is attained for an excitation pulse duration of 500 ns and the maximal pulse power is attained for a pulse duration of 100 ns. It is found that the optimal operation regime for the excilamp corresponds to the maximal values of the P T- W difference.

  1. Diode laser based water vapor DIAL using modulated pulse technique

    NASA Astrophysics Data System (ADS)

    Pham, Phong Le Hoai; Abo, Makoto

    2014-11-01

    In this paper, we propose a diode laser based differential absorption lidar (DIAL) for measuring lower-tropospheric water vapor profile using the modulated pulse technique. The transmitter is based on single-mode diode laser and tapered semiconductor optical amplifier with a peak power of 10W around 800nm absorption band, and the receiver telescope diameter is 35cm. The selected wavelengths are compared to referenced wavelengths in terms of random error and systematic errors. The key component of modulated pulse technique, a macropulse, is generated with a repetition rate of 10 kHz, and the modulation within the macropulse is coded according to a pseudorandom sequence with 100ns chip width. As a result, we evaluate both single pulse modulation and pseudorandom coded pulse modulation technique. The water vapor profiles conducted from these modulation techniques are compared to the real observation data in summer in Japan.

  2. First operation of a wiggler-focused, sheet beam free electron laser amplifier

    SciTech Connect

    Destler, W.W.; Cheng, S.; Zhang, Z.X.; Antonsen, T.M. Jr.; Granatstein, V.L.; Levush, B.; Rodgers, J. )

    1994-05-01

    A wiggler-focused, sheet beam free electron laser (FEL) amplifier utilizing a short-period wiggler magnet has been proposed as a millimeter-wave source for current profile modification and/or electron cyclotron resonance heating of tokamak plasmas. As proposed, such an amplifier would operate at a frequency of approximately 100--200 GHz with an output power of 1--10 MW CW. Electron beam energy would be in the range 500--1000 keV. To test important aspects of this concept, an initial sheet beam FEL amplifier experiment has been performed using a 1 mm[times]2 cm sheet beam produced by a pulse line accelerator with a pulse duration of 100 ns. The 500--570 keV, 4--18 A sheet beam is propagated through a 56 period uniform wiggler ([lambda][sub [ital w

  3. Computational modeling of Krypton gas puffs with tailored mass density profiles on Z

    SciTech Connect

    Jennings, Christopher A.; Ampleford, David J.; Lamppa, Derek C.; Hansen, Stephanie B.; Jones, Brent Manley; Harvey-Thompson, Adam James; Jobe, Marc Ronald Lee; Reneker, Joseph; Rochau, Gregory A.; Cuneo, Michael Edward; Strizic, T.

    2015-05-18

    Large diameter multi-shell gas puffs rapidly imploded by high current (~20 MA, ~100 ns) on the Z generator of Sandia National Laboratories are able to produce high-intensity Krypton K-shell emission at ~13 keV. Efficiently radiating at these high photon energies is a significant challenge which requires the careful design and optimization of the gas distribution. To facilitate this, we hydrodynamically model the gas flow out of the nozzle and then model its implosion using a 3-dimensional resistive, radiative MHD code (GORGON). This approach enables us to iterate between modeling the implosion and gas flow from the nozzle to optimize radiative output from this combined system. Furthermore, guided by our implosion calculations, we have designed gas profiles that help mitigate disruption from Magneto-Rayleigh–Taylor implosion instabilities, while preserving sufficient kinetic energy to thermalize to the high temperatures required for K-shell emission.

  4. A Fast Ramsey-Bordé Interferometer with Cold Lithium

    NASA Astrophysics Data System (ADS)

    Copenhaver, Eric; Cassella, Kayleigh; Mueller, Holger

    2016-05-01

    We demonstrate light-pulse interferometry with bosonic lithium in both Mach-Zehnder and Ramsey-Bordé geometries. We capture 12 million Li-7 atoms at 200 μK and build a fast interferometer with (~ 100 ns) stimulated Raman pulses and short interrogation times (tens to hundreds of microseconds). We achieve approximately 20 % of the maximum fringe contrast, which is limited to 25 % by non-interfering atomic trajectories. The contrast decays at a rate consistent with the limit set by thermal expansion out of the Raman beam. The signal in a Ramsey-Bordé interferometer scales inversely with mass and highlights the advantage of interferometry with light atoms like lithium. This allows for a measurement of the fine structure constant with shorter interrogation times than interferometers based on heavier atoms. Additionally, fast interferometers may have applications in the detection of high frequency signals resulting from exotic physics.

  5. Distribution of nanoscale nuclei in the amorphous dome of a phase change random access memory

    SciTech Connect

    Lee, Bong-Sub Darmawikarta, Kristof; Abelson, John R.; Raoux, Simone; Shih, Yen-Hao; Zhu, Yu

    2014-02-17

    The nanoscale crystal nuclei in an amorphous Ge{sub 2}Sb{sub 2}Te{sub 5} bit in a phase change memory device were evaluated by fluctuation transmission electron microscopy. The quench time in the device (∼10 ns) afforded more and larger nuclei in the melt-quenched state than in the as-deposited state. However, nuclei were even more numerous and larger in a test structure with a longer quench time (∼100 ns), verifying the prediction of nucleation theory that slower cooling produces more nuclei. It also demonstrates that the thermal design of devices will strongly influence the population of nuclei, and thus the speed and data retention characteristics.

  6. Isentropic Compression of Iron with the Z Accelerator

    SciTech Connect

    Asay, J.R.; Bernard, M.A.; Hall, C.A.; Hayes, D.B.; Holland, K.G.; McDaniel, D.H.; Rosenthal, S.E.; Spielman, R.B.; Stygar, W.A.

    1999-06-10

    Development of isentropic loading techniques is a long standing goal of the shock physics community. The authors have used the Sandia Z Accelerator to produce smoothly increasing pressure loading on planar iron specimens over time durations of 100 ns and for pressures to 300 Mbar. Free surface velocity measurements on the rear surface of the continuously loaded specimens were made on specimens 0.5-mm and 0.8-mm thick and clearly show the effects of wave evolution into the well known two-wave structure resulting from the {alpha}-{var_epsilon} phase transition beginning at 125 kbar. The resulting wave profiles are analyzed with a rate-dependent, phase transition model to extract information on phase transformation kinetics for isentropic compression of iron. Comparison of the experiments and calculations demonstrate the value of isentropic loading for studying phase transition kinetics.

  7. Microbubble-based model analysis of liquid breakdown initiation by a submicrosecond pulse

    NASA Astrophysics Data System (ADS)

    Qian, J.; Joshi, R. P.; Kolb, J.; Schoenbach, K. H.; Dickens, J.; Neuber, A.; Butcher, M.; Cevallos, M.; Krompholz, H.; Schamiloglu, E.; Gaudet, J.

    2005-06-01

    An electrical breakdown model for liquids in response to a submicrosecond (˜100ns) voltage pulse is presented, and quantitative evaluations carried out. It is proposed that breakdown is initiated by field emission at the interface of pre-existing microbubbles. Impact ionization within the microbubble gas then contributes to plasma development, with cathode injection having a delayed and secondary role. Continuous field emission at the streamer tip contributes to filament growth and propagation. This model can adequately explain almost all of the experimentally observed features, including dendritic structures and fluctuations in the prebreakdown current. Two-dimensional, time-dependent simulations have been carried out based on a continuum model for water, though the results are quite general. Monte Carlo simulations provide the relevant transport parameters for our model. Our quantitative predictions match the available data quite well, including the breakdown delay times and observed optical emission.

  8. Formation of nanoparticles during laser ablation of an iron target in a liquid

    SciTech Connect

    Sukhov, I A; Simakin, Aleksandr V; Shafeev, Georgii A; Viau, G; Garcia, C

    2012-05-31

    Formation of nanoparticles during laser ablation of a bulk iron target in water and isopropyl alcohol by pulsed near-IR laser radiation has been experimentally investigated. The experiments were performed using a 3-ns neodymium laser and a 100-ns ytterbium fibre laser. A size distribution function is obtained for the nanoparticles, which is peaking near 15 nm. The diffraction patterns of the nanoparticles exhibit pronounced peaks of metallic iron. An analysis of the nanoparticles by transmission electron microscopy shows that in some cases they have a core - shell structure. The nanoparticles formed by laser ablation have pronounced magnetic properties. The absorption spectra of colloids with iron nanoparticles contain peaks, which presumably correspond to the electron plasmon resonance in these particles.

  9. Note: A flexible light emitting diode-based broadband transient-absorption spectrometer

    NASA Astrophysics Data System (ADS)

    Gottlieb, Sean M.; Corley, Scott C.; Madsen, Dorte; Larsen, Delmar S.

    2012-05-01

    This Note presents a simple and flexible ns-to-ms transient absorption spectrometer based on pulsed light emitting diode (LED) technology that can be incorporated into existing ultrafast transient absorption spectrometers or operate as a stand-alone instrument with fixed-wavelength laser sources. The LED probe pulses from this instrument exhibit excellent stability (˜0.5%) and are capable of producing high signal-to-noise long-time (>100 ns) transient absorption signals either in a broadband multiplexed (spanning 250 nm) or in tunable narrowband (20 ns) operation. The utility of the instrument is demonstrated by measuring the photoinduced ns-to-ms photodynamics of the red/green absorbing fourth GMP phosphodiesterase/adenylyl cyclase/FhlA domain of the NpR6012 locus of the nitrogen-fixing cyanobacterium Nostoc punctiforme.

  10. Experimental study of high-Z gas buffers in gas-filled ICF engines

    NASA Astrophysics Data System (ADS)

    Rhodes, M. A.; Kane, J.; Loosmore, G.; DeMuth, J.; Latkowski, J.

    2011-03-01

    ICF power plants, such as the LIFE scheme at LLNL, may employ a high-Z, target-chamber gas-fill to moderate the first-wall heat-pulse due to x-rays and energetic ions released during target detonation. To reduce the uncertainties of cooling and beam/target propagation through such gas-filled chambers, we present a pulsed plasma source producing 2-5 eV plasma comprised of high-Z gases. We use a 5-kJ, 100-ns theta discharge for high peak plasma-heating-power, an electrode-less discharge for minimizing impurities, and unobstructed axial access for diagnostics and beam (and/or target) propagation studies. We will report on the plasma source requirements, design process, and the system design.

  11. Electrothermal Annealing (ETA) Method to Enhance the Electrical Performance of Amorphous-Oxide-Semiconductor (AOS) Thin-Film Transistors (TFTs).

    PubMed

    Kim, Choong-Ki; Kim, Eungtaek; Lee, Myung Keun; Park, Jun-Young; Seol, Myeong-Lok; Bae, Hagyoul; Bang, Tewook; Jeon, Seung-Bae; Jun, Sungwoo; Park, Sang-Hee K; Choi, Kyung Cheol; Choi, Yang-Kyu

    2016-09-14

    An electro-thermal annealing (ETA) method, which uses an electrical pulse of less than 100 ns, was developed to improve the electrical performance of array-level amorphous-oxide-semiconductor (AOS) thin-film transistors (TFTs). The practicality of the ETA method was experimentally demonstrated with transparent amorphous In-Ga-Zn-O (a-IGZO) TFTs. The overall electrical performance metrics were boosted by the proposed method: up to 205% for the trans-conductance (gm), 158% for the linear current (Ilinear), and 206% for the subthreshold swing (SS). The performance enhancement were interpreted by X-ray photoelectron microscopy (XPS), showing a reduction of oxygen vacancies in a-IGZO after the ETA. Furthermore, by virtue of the extremely short operation time (80 ns) of ETA, which neither provokes a delay of the mandatory TFTs operation such as addressing operation for the display refresh nor demands extra physical treatment, the semipermanent use of displays can be realized. PMID:27552134

  12. Modulator considerations for beam chopping in the low energy beam transport at the SSC Laboratory

    SciTech Connect

    Anderson, D.; Pappas, G.

    1991-06-01

    Beam chopping in the low energy transport line at the Superconducting Super Collider Laboratory is accomplished using an electrostatic deflection system. LINAC requirements dictate the design of two modulators operating at 10 Hz with rise and fall times (as measured from approximately 10--99%) of {approximately}100 ns. Design of the first pulser, normally at 10 kV and pulsed to ground potential, utilizes a transformer-coupled diode-clamped solid state circuit to achieve the 2--35 {mu}s pulse width range required. The second pulser, which pulses from ground to approximately 7 kV, relies on a series vacuum tube circuit. The current designs, as well as recent test results and other circuit topologies considered, will be presented. 6 refs.

  13. Temporal response of a surface flashover on a velvet cathode in a relativistic diode

    DOE PAGES

    Coleman, J. E.; Moir, D. C.; Crawford, M. T.; Welch, D. R.; Offermann, D. T.

    2015-03-11

    Surface flashover of a carbon fiber velvet cathode generates a discharge from which electrons are relativistically accelerated to γ ranging from 4.9 to 8.8 through a 17.8 cm diode. It is assumed that this discharge is a hydrocarbon mixture. Our principal objective of these experiments is to quantify the dynamics over the ~100 ns pulse of the plasma discharge generated on the surface of the velvet cathode and across the anode-cathode (A-K) gap. A qualitative comparison of calculated and measured results is presented, which includes time resolved measurements with a photomultiplier tube and charge-coupled device images. Additionally, initial visible spectroscopymore » measurements will also be presented confirming the ion species are dominated by hydrogen.« less

  14. Experimental Study of High-Z Gas Buffers in Gas-Filled ICF Engines

    SciTech Connect

    Rhodes, M A; Kane, J; Loosmore, G; DeMuth, J; Latkowski, J

    2010-12-03

    ICF power plants, such as the LIFE scheme at LLNL, may employ a high-Z, target-chamber gas-fill to moderate the first-wall heat-pulse due to x-rays and energetic ions released during target detonation. To reduce the uncertainties of cooling and beam/target propagation through such gas-filled chambers, we present a pulsed plasma source producing 2-5 eV plasma comprised of high-Z gases. We use a 5-kJ, 100-ns theta discharge for high peak plasma-heating-power, an electrode-less discharge for minimizing impurities, and unobstructed axial access for diagnostics and beam (and/or target) propagation studies. We will report on the plasma source requirements, design process, and the system design.

  15. Time-resolved photoluminescence of type-II quantum dots and isoelectronic centers in Zn-Se-Te superlattice structures

    NASA Astrophysics Data System (ADS)

    Cheung, M. C.-K.; Cartwright, A. N.; Sellers, I. R.; McCombe, B. D.; Kuskovsky, I. L.

    2008-01-01

    Spectrally and time-resolved photoluminescence of a ZnTe /ZnSe superlattice reveals a smooth transition of the photoluminescence (PL) lifetime from ˜100ns at 2.35eV to less than a few nanoseconds at 2.8eV. The significant increase of the lifetime in the low energy region is strong evidence to support the formation of type-II quantum dots (QDs), since in these nanostructures the spatial separation of carriers is increased. The shorter lived emission above 2.5eV is attributed to excitons bound to Te isoelectronic centers in the ZnSe matrix. The smooth transition of the PL lifetime confirms that clusters of these Te atoms evolve into type-II ZnTe /ZnSe QDs.

  16. Optical properties of doped potassium gadolinium tungstate single crystals

    NASA Astrophysics Data System (ADS)

    Michalski, E.; Zmija, Jozef; Mierczyk, Zygmunt; Majchrowski, Andrzej; Kopczynski, Krzysztof; Cichowski, S.; Wojtanowski, J.

    2001-08-01

    Single crystals of double tungstates find applications as laser materials having very good parameters. One of the intensively investigated material sis KGD(WO4)2 doped with rare earth elements. Single crystal of KGd(WO4)2 were grown with the use of Top Seeded Solution Growth technique from K2W2O7 solvent. The crystals have low absorption loses and show high lasing efficiency. Optical investigations of as grown KGW:Nd single crystal confirmed their good optical quality and high absorption coefficient near 810 nm, what in connection with strong luminescence near 1067 nm allows fabrication of diode pumped microchip lasers working both in CW and giant pulse regime. Absorption and luminescence spectra of Nd3+ doped KGW single crystals are presented. Laser action was obtained in form of 128.5 kHz train of 100 ns giant pluses due to YAG:Cr4+ passive Q-switch.

  17. Formation of nanoparticles during laser ablation of an iron target in a liquid

    NASA Astrophysics Data System (ADS)

    Sukhov, I. A.; Simakin, Aleksandr V.; Shafeev, Georgii A.; Viau, G.; Garcia, C.

    2012-05-01

    Formation of nanoparticles during laser ablation of a bulk iron target in water and isopropyl alcohol by pulsed near-IR laser radiation has been experimentally investigated. The experiments were performed using a 3-ns neodymium laser and a 100-ns ytterbium fibre laser. A size distribution function is obtained for the nanoparticles, which is peaking near 15 nm. The diffraction patterns of the nanoparticles exhibit pronounced peaks of metallic iron. An analysis of the nanoparticles by transmission electron microscopy shows that in some cases they have a core — shell structure. The nanoparticles formed by laser ablation have pronounced magnetic properties. The absorption spectra of colloids with iron nanoparticles contain peaks, which presumably correspond to the electron plasmon resonance in these particles.

  18. Theoretical model for plasma opening switch

    SciTech Connect

    Baker, L.

    1980-07-01

    The theory of an explosive plasma switch is developed and compared with the experimental results of Pavlovskii and work at Sandia. A simple analytic model is developed, which predicts that such switches may achieve opening times of approximately 100 ns. When the switching time is limited by channel mixing it scales as t = C(m d/sub 0/)/sup 1/2/P/sub 0//sup 2/P/sub e//sup -5/2/ where m is the foil mass per unit area, d/sub 0/ the channel thickness and P/sub 0/ the channel pressure (at explosive breakout), P/sub e/ the explosive pressure, C a constant of order 10 for c.g.s. units. Thus faster switching times may be achieved by minimizing foil mass and channel pressure, or increasing explosive product pressure, with the scaling exponents as shown suggesting that changes in pressures would be more effective.

  19. A new methodology for determining recombination parameters using an RF photoconductance instrument

    SciTech Connect

    Sinton, R.A.; Cuevas, A.

    1995-08-01

    Measurements of minority-carrier lifetime in silicon wafers provide an effective technique for process control and device-physics optimization. For example, detailed measurements of minority-carrier lifetime vs. injection level can allow a nearly complete experimental optimization of a solar cell design and process. This extended abstract describes a methodology that allows this fully characterization by using a relatively simple RF photoconductance-decay tool. By analyzing the quasi-steady-state photoconductance as a function of incident light intensity, information corresponding to an I{sub sc}-V{sub oc} curve can be obtained from a non-contacted silicon wafer. This information is available at various stages during the solar cell fabrication process. The use of steady-state photoconductance instead of transient photoconductance makes use of simple electronics and light sources, yet it has the capability to measure lifetimes down into the 100 ns range.

  20. Passive mitigation of load debris in a magnetically insulated transmission line.

    SciTech Connect

    Wagoner, Timothy C.; Seidel, David Bruce; Savage, Mark Edward; Wakeland, Peter Eric; Mendel, Clifford Will, Jr.; Pointon, Timothy David; Romero, Dustin Heinz

    2005-06-01

    The Z driver at Sandia National Laboratories delivers one to two megajoules of electromagnetic energy inside its {approx}10 cm radius final feed in 100 ns. The high current ({approx}20 MA) at small diameter produces magnetic pressures well above yield strengths for metals. The metal conductors stay in place due to inertia long enough to deliver current to the load. Within milliseconds however, fragments of metal escape the load region at high velocity. Much of the hardware and diagnostics inside the vacuum chamber is protected from this debris by blast shields with small view ports, and fast-closing valves. The water-vacuum insulator requires different protection because the transmission line debris shield should not significantly raise the inductance or perturb the self- magnetically insulated electron flow. This report shows calculations and results from a design intended to protect the insulator assembly.

  1. Observation of fast expansion velocity with insulating tungsten wires on ˜80 kA facility

    NASA Astrophysics Data System (ADS)

    Li, M.; Zhang, J. H.; Wu, J.; Li, Y.; Sun, T. P.; Wang, L. P.; Sheng, L.; Qiu, M. T.; Mao, W. T.; Li, X. W.

    2016-07-01

    This paper presents experimental results on the effects of insulating coatings on tungsten planar wire array Z-pinches on an 80 kA, 100 ns current facility. Expansion velocity is obviously increased from ˜0.25 km/s to ˜3.5 km/s by using the insulating coatings. It can be inferred that the wire cores are in gaseous state with this fast expansion velocity. An optical framing camera and laser probing images show that the standard wire arrays have typical ablation process which is similar to their behaviors on mega-ampere facilities. The ablation process and precursor plasma are suppressed for dielectric tungsten wires. The wire array implosion might be improved if these phenomena can be reproduced on Mega-ampere facilities.

  2. Design of the biosonar simulator for dolphin's clicks waveform reproduction

    NASA Astrophysics Data System (ADS)

    Ishii, Ken; Akamatsu, Tomonari; Hatakeyama, Yoshimi

    1992-03-01

    The emitted clicks of Dall's porpoises consist of a pulse train of burst signals with an ultrasonic carrier frequency. The authors have designed a biosonar simulator to reproduce the waveforms associated with a dolphin's clicks underwater. The total reproduction system consists of a click signal acquisition block, a waveform analysis block, a memory unit, a click simulator, and a underwater, ultrasonic wave transmitter. In operation, data stored in an EPROM (Erasable Programmable Read Only Memory) are read out sequentially by a fast clock and converted to analog output signals. Then an ultrasonic power amplifier reproduces these signals through a transmitter. The click signal replaying block is referred to as the BSS (Biosonar Simulator). This is what simulates the clicks. The details of the BSS are described in this report. A unit waveform is defined. The waveform is divided into a burst period and a waiting period. Clicks are a sequence based on a unit waveform, and digital data are sequentially read out from an EPROM of waveform data. The basic parameters of the BSS are as follows: (1) reading clock, 100 ns to 25.4 microseconds; (2) number of reading clock, 34 to 1024 times; (3) counter clock in a waiting period, 100 ns to 25.4 microseconds; (4) number of counter clock, zero to 16,777,215 times; (5) number of burst/waiting repetition cycle, one to 128 times; and (6) transmission level adjustment by a programmable attenuator, zero to 86.5 dB. These basic functions enable the BSS to replay clicks of Dall's porpoise precisely.

  3. Optical properties of water for the Yangbajing water cherenkov detector

    NASA Astrophysics Data System (ADS)

    Gao, Shang-qi; Sun, Zhi-bin; Jiang, Yuan-da; Wang, Chao; Du, Ke-ming

    2011-08-01

    Cherenkov radiation is used to study the production of particles during collisions, cosmic rays detections and distinguishing between different types of neutrinos and electrons. The optical properties of water are very important to the research of Cherenkov Effect. Lambert-beer law is a method to study the attenuation of light through medium. In this paper, optical properties of water are investigated by use of a water attenuation performance test system. The system is composed of the light-emitting diode (LED) light source and the photon receiver models. The LED light source model provides a pulse light signal which frequency is 1 kHz and width is 100ns. In photon receiver model, a high sensitivity photomultiplier tube (PMT) is used to detect the photons across the water. Because the output voltage amplitude of PMT is weak which is from 80mv to 120mV, a low noise pre-amplifier is used to improve the detector precise. An effective detector maximum time window of PMT is 100ns for a long lifetime, so a peak holder circuit is used to hold the maximum peak amplitude of PMT for the induced photons signal before the digitalization. In order to reduce the noise of peak holder, a multi-pulse integration is used before the sampling of analog to digital converter. At last, the detector of photons from the light source to the PMT across the water is synchronized to the pulse width of the LED. In order to calculate the attenuation coefficient and attenuation length of water precisely, the attenuation properties of air-to-water boundary is considered in the calculation.

  4. Nanosecond plasma-mediated electrosurgery with elongated electrodes

    NASA Astrophysics Data System (ADS)

    Vankov, Alexander; Palanker, Daniel

    2007-06-01

    Progress in interventional medicine is associated with the development of more delicate and less invasive surgical procedures, which requires more precise and less traumatic, yet affordable, surgical instruments. Previously we reported on the development of the pulsed electron avalanche knife for dissection of soft tissue in liquid media using the 100 ns plasma-mediated electric discharges applied via a 25 μm disk microelectrode. Cavitation bubbles accompanying explosive vaporization of the liquid medium in front of such a pointed electrode produced a series of craters that did not always merge into a continuous cut. In addition, this approach of surface ablation provided a limited depth of cutting. Application of an elongated electrode capable of cutting with its edge rather than just with its pointed apex faces a problem of nonuniformity of the electric field on a nonspherical electrode. In this article we explore dynamics of the plasma-mediated nanosecond discharges in liquid medium in positive and negative polarities and describe the geometry of an electrode that provides a sufficiently uniform electric field along an extended edge of a surgical probe. A highly enhanced and uniform electric field was obtained on very sharp (2.5 μm) exposed edges of a planar electrode insulated on its flat sides. Uniform ionization and simultaneous vaporization was obtained along the whole edge of such a blade with 100 ns pulses at 4-6 kV. A continuous cutting rate of 1 mm/s in the retina and in soft membranes was achieved at a pulse repetition rate of 100 Hz. The collateral damage zone at the edges of incision did not exceed 80 μm. Negative polarity was found advantageous due to the lower rate of electrode erosion and due to better spatial confinement of the plasma-mediated discharge in liquid.

  5. Self-pumped phase conjugation and four-wave mixing in 0- and 45-deg-cut n-type BaTiO3:Co

    NASA Technical Reports Server (NTRS)

    Garrett, M. H.; Chang, J. Y.; Jenssen, H. P.; Warde, C.

    1993-01-01

    Relatively fast self-pumped phase-conjugate and four-wave-mixing rise times are reported in n-type cobalt-doped barium titanate. With the crystal oriented in a 45-deg cut as compared with the same crystal in a 0-deg cut we find a factor of 3 decrease in the 0-90-percent rise time to 800 ms with 25-mW input power at 514.5 nm. Also, the self-pumped phase-conjugate reflectivity increases from 20 to 40 percent. We deduce that the phase conjugation is from internally seeded stimulated photorefractive backscattering. The four-wave-mixing rise time of the 45-deg-cut crystal is 4 ms with a reflectivity of 48 percent when the pumping beams are derived from self-pumped phase conjugation that has an input power of 25 mW.

  6. Scattering of sonic booms by anisotropic turbulence in the atmosphere

    PubMed

    Kelly; Raspet; Bass

    2000-06-01

    An earlier paper [J. Acoust. Soc. Am. 98, 3412-3417 (1995)] reported on the comparison of rise times and overpressures of sonic booms calculated with a scattering center model of turbulence to measurements of sonic boom propagation through a well-characterized turbulent layer under moderately turbulent conditions. This detailed simulation used spherically symmetric scatterers to calculate the percentage of occurrence histograms of received overpressures and rise times. In this paper the calculation is extended to include distorted ellipsoidal turbules as scatterers and more accurately incorporates the meteorological data into a determination of the number of scatterers per unit volume. The scattering center calculation overpredicts the shifts in rise times for weak turbulence, and still underpredicts the shift under more turbulent conditions. This indicates that a single-scatter center-based model cannot completely describe sonic boom propagation through atmospheric turbulence. PMID:10875351

  7. A model experiment to study sonic boom propagation through turbulence. Part III: validation of sonic boom propagation models.

    PubMed

    Lipkens, Bart

    2002-01-01

    In previous papers, we have shown that model experiments are successful in simulating the propagation of sonic booms through the atmospheric turbulent boundary layer. The results from the model experiment, pressure wave forms of spark-produced N waves and turbulence characteristics of the plane jet, are used to test various sonic boom models for propagation through turbulence. Both wave form distortion models and rise time prediction models are tested. Pierce's model [A. D. Pierce, "Statistical theory of atmospheric turbulence effects on sonic boom rise times," J. Acoust. Soc. Am. 49, 906-924 (1971)] based on the wave front folding mechanism at a caustic yields an accurate prediction for the rise time of the mean wave form after propagation through the turbulence. PMID:11837956

  8. Pulse switching for high energy lasers

    NASA Technical Reports Server (NTRS)

    Laudenslager, J. B.; Pacala, T. J. (Inventor)

    1981-01-01

    A saturable inductor switch for compressing the width and sharpening the rise time of high voltage pulses from a relatively slow rise time, high voltage generator to an electric discharge gas laser (EDGL) also provides a capability for efficient energy transfer from a high impedance primary source to an intermediate low impedance laser discharge network. The switch is positioned with respect to a capacitive storage device, such as a coaxial cable, so that when a charge build-up in the storage device reaches a predetermined level, saturation of the switch inductor releases or switches energy stored in the capactive storage device to the EDGL. Cascaded saturable inductor switches for providing output pulses having rise times of less than ten nanoseconds and a technique for magnetically biasing the saturable inductor switch are disclosed.

  9. Influence of Contactopy on Two-Dimensional Brazil-Nut Effect

    NASA Astrophysics Data System (ADS)

    Kesuma, Teja; Praja Purwa Aji, Dimas; Viridi, Sparisoma; Suprijadi

    2016-01-01

    Using hard sphere collision scheme and molecular dynamics method simulation, two-dimension Brazil-Nut Effect (BNE) is conducted. BNE inital configurations are artificially created to obtain number of contacts between the grains, called as contactopy. It is observed that from initial condition until the end of BNE observation, center-of-mass in vertical direction tends to decrease, while contactopy tends to increase, which are similar to the reported results in a Gedankenexperiment (Viridi et al., 2014). Initial configurations which are also dependent on contactopy influence the rise time since it can override influence of density ratio that should affect rise time (Möbius et al., 2001). We investigate on how the intruder rise time influenced by contactopy, as well as density.

  10. Ultrafast polarization switching in thin-film ferroelectrics

    NASA Astrophysics Data System (ADS)

    Li, J.; Nagaraj, B.; Liang, H.; Cao, W.; Lee, Chi. H.; Ramesh, R.

    2004-02-01

    We present an experimental approach to study the ultrafast polarization switching dynamics in thin-film ferroelectrics. A semiconductor photoconductive switch with femtosecond laser illumination is used as a "pulse generator" to produce jitter-free, sub-100 ps rise time step-function-like electrical pulses. Quantitative measurements yield a polarization switching time, ts, of ˜220 ps when measured with a 5 V, 68 ps rise time input electrical pulse. Modeling of the switching transients using the Merz-Ishibashi model and Merz-Shur model of switching kinetics yields a quantitative estimate of the characteristic switching time constant, t0, of ˜70-90 ps.

  11. Tritium monitor with improved gamma-ray discrimination

    DOEpatents

    Cox, Samson A.; Bennett, Edgar F.; Yule, Thomas J.

    1985-01-01

    Apparatus and method for selective measurement of tritium oxide in an environment which may include other radioactive components and gamma radiation, the measurement including the selective separation of tritium oxide from a sample gas through a membrane into a counting gas, the generation of electrical pulses individually representative by rise times of tritium oxide and other radioactivity in the counting gas, separation of the pulses by rise times, and counting of those pulses representative of tritium oxide. The invention further includes the separate measurement of any tritium in the sample gas by oxidizing the tritium to tritium oxide and carrying out a second separation and analysis procedure as described above.

  12. Tritium monitor with improved gamma-ray discrimination

    DOEpatents

    Cox, S.A.; Bennett, E.F.; Yule, T.J.

    1982-10-21

    Apparatus and method are presented for selective measurement of tritium oxide in an environment which may include other radioactive components and gamma radiation, the measurement including the selective separation of tritium oxide from a sample gas through a membrane into a counting gas, the generation of electrical pulses individually representative by rise times of tritium oxide and other radioactivity in the counting gas, separation of the pulses by rise times, and counting of those pulses representative of tritium oxide. The invention further includes the separate measurement of any tritium in the sample gas by oxidizing the tritium to tritium oxide and carrying out a second separation and analysis procedure as described above.

  13. High gain photoconductive semiconductor switching

    SciTech Connect

    Zutavern, F.J.; Loubriel, G.M.; O'Malley, M.W.; Helgeson, W.D.; McLaughlin, D.L.

    1991-01-01

    Switching properties are reported for high gain photoconductive semiconductor switches (PCSS). A 200 ps pulse width laser was used in tests to examine the relations between electric field, rise time, delay, and minimum optical trigger energy for switches which reached 80 kV in a 50 {Omega} transmission line with rise times as short as 600 ps. Infrared photoluminescence was imaged during high gain switching providing direct evidence for current filamentation. Implications of these measurements for the theoretical understanding and practical development of these switches are discussed. 16 refs., 10 figs.

  14. Complete Genome Sequence of Phodopus sungorus Papillomavirus Type 1 (PsPV1), a Novel Member of the Pipapillomavirus Genus, Isolated from a Siberian Hamster.

    PubMed

    Kocjan, Boštjan J; Hošnjak, Lea; Račnik, Joško; Zadravec, Marko; Poljak, Mario

    2014-04-10

    We report the complete genomic sequence of Phodopus sungorus papillomavirus type 1 (PsPV1), isolated from an anogenital lesion of a Siberian hamster. PsPV1 is taxonomically classified in the genus Pipapillomavirus and is most closely related to Mesocricetus auratus papillomavirus 1 (MaPV1).

  15. East Antarctic ice-sheet dynamics between 5.2 and 0 Ma from a high-resolution terrigenous particle size record, ODP Site 1165, Prydz Bay-Cooperation Sea

    USGS Publications Warehouse

    Passchier, S.

    2007-01-01

    This paper discusses a 5.2-0 Ma high-resolution terrigenous particle size record recovered from a sediment drift off East Antarctica. The particle size properties of Hole 1165B are interpreted in the context of previously acquired data on a continental shelf to slope transect drilled by ODP Leg 188 in Prydz Bay and the Cooperation Sea. The new data indicate that the Lambert ice stream stayed predominantly landward of the shelf break in the early Pliocene (5.2-3.5 Ma) with periods of ice sheet recession on land. The middle Pliocene (3.5-3.1 Ma) is characterized as major ice expansion during glacials with deposition of laminated clays from meltwater plumes on the continental rise, alternating with periods of ice recession. A change in sedimentary facies and a decrease in sedimentation rates occurred at ~3.1 Ma indicating a more retreated Lambert Glacier. Between 2.5 and 1 Ma the ice stream was generally stable and had become cold-based with ice flow in a glacial trough extending to the shelf break. Three-four large pulses of coarse-grained glacigenic debris mark the record at ~1 Ma. These are interpreted as extensive calving due to decoupling of the marine terminus from its bed in response to Northern Hemisphere deglaciations and associated sea level rises.

  16. Changes in ethylene signaling and MADS box gene expression are associated with banana finger drop.

    PubMed

    Hubert, O; Piral, G; Galas, C; Baurens, F-C; Mbéguié-A-Mbéguié, D

    2014-06-01

    Banana finger drop was examined in ripening banana harvested at immature (iMG), early (eMG) and late mature green (lMG) stages, with contrasting ripening rates and ethylene sensitivities. Concomitantly, 11 ethylene signal transduction components (ESTC) and 6 MADS box gene expressions were comparatively studied in median (control zone, CZ) and pedicel rupture (drop zone DZ) areas in peel tissue. iMG fruit did not ripen or develop finger drop while eMG and lMG fruits displayed a similar finger drop pattern. Several ESTC and MADS box gene mRNAs were differentially induced in DZ and CZ and sequentially in eMG and lMG fruits. MaESR2, 3 and MaEIL1, MaMADS2 and MaMADS5 had a higher mRNA level in eMG and acted earlier, whereas MaERS1, MaCTR1, MaEIL3/AB266319, MaEIL4/AB266320 and MaEIL5/AB266321, MaMADS4 and to a lesser extent MaMADS2 and 5 acted later in lMG. In this fruit, MaERS1 and 3, MaCTR1, MaEIL3, 4 and MaEIL5/AB266321, and MaMADS4 were enhanced by finger drop, suggesting their specific involvement in this process. MaEIL1, MaMADS1 and 3, induced at comparable levels in DZ and CZ, are probably related to the overall fruit ripening process. These findings led us to consider that developmental cues are the predominant finger drop regulation factor. PMID:24767119

  17. [sup 40]Ar/[sup 39]Ar isotopic dates from the Cripple Creek gold-Telluride district, Colorado: Constraints on the timing of magmatism and mineralization

    SciTech Connect

    Kelley, K.D.; Snee, L.W. ); Thompson, T.B. . Dept. of Earth Resources)

    1993-04-01

    The Cripple Creek district is within a Tertiary diatreme-intrusive complex, a steep-walled basin in Proterozoic pelitic and igneous rocks that is filled with terrigenous sedimentary rocks, volcanic and hydrothermal breccias, and tuffs. The orebodies occur as veins in Proterozoic and Tertiary rocks or as deposits localized within hydrothermal breccia bodies or disseminated in diatreme breccias. [sup 40]Ar/[sup 39]Ar dates from igneous rocks demonstrate the approximately contemporaneous emplacement of the most differentiated phonolitic rocks. Three sanidine samples from phonolite yield apparent ages ranging from 30.9 [+-] 0.1 to 31.8 [+-] 0.1 Ma (1 sigma). Biotite and sanidine age spectra from relatively less differentiated tephriphonolite are discordant; the emplacement age is estimated to be between 31.4 [+-] 0.1 and 32.5 [+-] 0.1 Ma. A maximum age of 31.5 [+-] 0.1 Ma was obtained on a whole-rock sample of trachyandesite. The mafic phonolitic rocks are relatively younger. A sample of the Isabella dike, a phonotephrite dike cutting phonolite, yields a whole-rock age of 28.7 [+-] 0.04 Ma. The data suggest that mineralization both predates and postdates emplacement of the mafic phonolitic rocks. Hydrothermal biotite in a vein cutting phonolite yields an age of 29.9 [+-] 0.1 Ma. The age spectrum of adularia from a vein cutting volcaniclastic rocks is difficult to interpret due to the presence of excess argon, but an age is estimated to be between 29.5 and 30.4 Ma. In the vicinity of the phonotephrite dike, field evidence suggests that vein mineralization postdates emplacement of the dike; potassium feldspar from potassium altered phonolite in the vicinity of mineralized rock yields ages of 28.2 [+-] 0.1 and 28.8 [+-] 0.1 Ma.

  18. LDRD final report on confinement of cluster fusion plasmas with magnetic fields.

    SciTech Connect

    Argo, Jeffrey W.; Kellogg, Jeffrey W.; Headley, Daniel Ignacio; Stoltzfus, Brian Scott; Waugh, Caleb J.; Lewis, Sean M.; Porter, John Larry, Jr.; Wisher, Matthew; Struve, Kenneth William; Savage, Mark Edward; Quevedo, Hernan J.; Bengtson, Roger

    2011-11-01

    Two versions of a current driver for single-turn, single-use 1-cm diameter magnetic field coils have been built and tested at the Sandia National Laboratories for use with cluster fusion experiments at the University of Texas in Austin. These coils are used to provide axial magnetic fields to slow radial loss of electrons from laser-produced deuterium plasmas. Typical peak field strength achievable for the two-capacitor system is 50 T, and 200 T for the ten-capacitor system. Current rise time for both systems is about 1.7 {mu}s, with peak current of 500 kA and 2 MA, respectively. Because the coil must be brought to the laser, the driver needs to be portable and drive currents in vacuum. The drivers are complete but laser-plasma experiments are still in progress. Therefore, in this report, we focus on system design, initial tests, and performance characteristics of the two-capacitor and ten-capacitors systems. The questions of whether a 200 T magnetic field can retard the breakup of a cluster-fusion plasma, and whether this field can enhance neutron production have not yet been answered. However, tools have been developed that will enable producing the magnetic fields needed to answer these questions. These are a two-capacitor, 400-kA system that was delivered to the University of Texas in 2010, and a 2-MA ten-capacitor system delivered this year. The first system allowed initial testing, and the second system will be able to produce the 200 T magnetic fields needed for cluster fusion experiments with a petawatt laser. The prototype 400-kA magnetic field driver system was designed and built to test the design concept for the system, and to verify that a portable driver system could be built that delivers current to a magnetic field coil in vacuum. This system was built copying a design from a fixed-facility, high-field machine at LANL, but made to be portable and to use a Z-machine-like vacuum insulator and vacuum transmission line. This system was sent to the

  19. Bipolar square-wave current source for transient electromagnetic systems based on constant shutdown time

    NASA Astrophysics Data System (ADS)

    Wang, Shilong; Yin, Changchun; Lin, Jun; Yang, Yu; Hu, Xueyan

    2016-03-01

    Cooperative work of multiple magnetic transmitting sources is a new trend in the development of transient electromagnetic system. The key is the bipolar current waves shutdown, concurrently in the inductive load. In the past, it was difficult to use the constant clamping voltage technique to realize the synchronized shutdown of currents with different peak values. Based on clamping voltage technique, we introduce a new controlling method with constant shutdown time. We use the rising time to control shutdown time and use low voltage power source to control peak current. From the viewpoint of the circuit energy loss, by taking the high-voltage capacitor bypass resistance and the capacitor of the passive snubber circuit into account, we establish the relationship between the rising time and the shutdown time. Since the switch is not ideal, we propose a new method to test the shutdown time by the low voltage, the high voltage and the peak current. Experimental results show that adjustment of the current rising time can precisely control the value of the clamp voltage. When the rising time is fixed, the shutdown time is unchanged. The error for shutdown time deduced from the energy consumption is less than 6%. The new controlling method on current shutdown proposed in this paper can be used in the cooperative work of borehole and ground transmitting system.

  20. Current Mode Logic Fan Out

    2011-05-07

    Current mode logic is used in high speed timing systems for particle accelerators due to the fast rise time of the electrical signal. This software provides the necessary documentation to produce multiple copies of a single input for distribution to multiple devices. This software supports the DOE mission by providing a method for producing high speed signals in accelerator timing systems.

  1. Amplitude Envelope Perception, Phonology and Prosodic Sensitivity in Children with Developmental Dyslexia

    ERIC Educational Resources Information Center

    Goswami, Usha; Gerson, Danielle; Astruc, Luisa

    2010-01-01

    Here we explore relations between auditory perception of amplitude envelope structure, prosodic sensitivity, and phonological awareness in a sample of 56 typically-developing children and children with developmental dyslexia. We examine whether rise time sensitivity is linked to prosodic sensitivity, and whether prosodic sensitivity is linked to…

  2. Quantifying the evidence for dark matter in CoGeNT data

    SciTech Connect

    Davis, Jonathan H.; McCabe, Christopher; Boehm, Céline E-mail: christopher.mccabe@durham.ac.uk

    2014-08-01

    We perform an independent analysis of data from the CoGeNT direct detection experiment to quantify the evidence for dark matter recoils. We critically re-examine the assumptions that enter the analysis, focusing specifically on the separation of bulk and surface events, the latter of which constitute a large background. This separation is performed using the event rise-time, with the surface events being slower on average. We fit the rise-time distributions for the bulk and surface events with a log-normal and Pareto distribution (which gives a better fit to the tail in the bulk population at high rise-times) and account for the energy-dependence of the bulk fraction using a cubic spline. Using Bayesian and frequentist techniques and additionally investigating the effect of varying the rise-time cut, the bulk background spectrum and bin-sizes, we conclude that the CoGeNT data show a preference for light dark matter recoils at less than 1σ.

  3. Microprocessor-Based Neural-Pulse-Wave Analyzer

    NASA Technical Reports Server (NTRS)

    Kojima, G. K.; Bracchi, F.

    1983-01-01

    Microprocessor-based system analyzes amplitudes and rise times of neural waveforms. Displaying histograms of measured parameters helps researchers determine how many nerves contribute to signal and specify waveform characteristics of each. Results are improved noise rejection, full or partial separation of overlapping peaks, and isolation and identification of related peaks in different histograms. 2

  4. System measures response time of photomultiplier tubes

    NASA Technical Reports Server (NTRS)

    Lauver, M. R.

    1968-01-01

    Calibration system enables precise determination of rise time of photosensitive detectors. To perform a calibration, the time-voltage curve of the excitation voltage for a light source is compared with the time-voltage curve of the voltage output from a photosensitive detector which is responding to the light.

  5. Basic Auditory Processing Deficits in Dyslexia: Systematic Review of the Behavioral and Event-Related Potential/Field Evidence

    ERIC Educational Resources Information Center

    Hämäläinen, Jarmo A.; Salminen, Hanne K.; Leppänen, Paavo H. T.

    2013-01-01

    A review of research that uses behavioral, electroencephalographic, and/or magnetoencephalographic methods to investigate auditory processing deficits in individuals with dyslexia is presented. Findings show that measures of frequency, rise time, and duration discrimination as well as amplitude modulation and frequency modulation detection were…

  6. As-Built design specification for PARPLT. [program to produce scatter plots of crop greenness profile parameters

    NASA Technical Reports Server (NTRS)

    Tompkins, M. A.; Cheng, D. E. (Principal Investigator)

    1981-01-01

    The design and implementation of the PARPLT program are described. The program produces scatter plots of the greenness profile derived parameters alpha, beta, and t sub o computed by the CLASFYG program (alpha being the approximate greenness rise time; beta, the greenness decay time; and t sub o, the spectral crop emergence date). Statistical information concerning the parameters is also computed.

  7. Top-level dynamics and the regulated gene response of feed-forward loop transcriptional motifs

    NASA Astrophysics Data System (ADS)

    Mayo, Michael; Abdelzaher, Ahmed; Perkins, Edward J.; Ghosh, Preetam

    2014-09-01

    Feed-forward loops are hierarchical three-node transcriptional subnetworks, wherein a top-level protein regulates the activity of a target gene via two paths: a direct-regulatory path, and an indirect route, whereby the top-level proteins act implicitly through an intermediate transcription factor. Using a transcriptional network of the model bacterium Escherichia coli, we confirmed that nearly all types of feed-forward loop were significantly overrepresented in the bacterial network. We then used mathematical modeling to study their dynamics by manipulating the rise times of the top-level protein concentration, termed the induction time, through alteration of the protein destruction rates. Rise times of the regulated proteins exhibited two qualitatively different regimes, depending on whether top-level inductions were "fast" or "slow." In the fast regime, rise times were nearly independent of rapid top-level inductions, indicative of biological robustness, and occurred when RNA production rate-limits the protein yield. Alternatively, the protein rise times were dependent upon slower top-level inductions, greater than approximately one bacterial cell cycle. An equation is given for this crossover, which depends upon three parameters of the direct-regulatory path: transcriptional cooperation at the DNA-binding site, a protein-DNA dissociation constant, and the relative magnitude of the top-level protien concentration.

  8. Top-level dynamics and the regulated gene response of feed-forward loop transcriptional motifs.

    PubMed

    Mayo, Michael; Abdelzaher, Ahmed; Perkins, Edward J; Ghosh, Preetam

    2014-09-01

    Feed-forward loops are hierarchical three-node transcriptional subnetworks, wherein a top-level protein regulates the activity of a target gene via two paths: a direct-regulatory path, and an indirect route, whereby the top-level proteins act implicitly through an intermediate transcription factor. Using a transcriptional network of the model bacterium Escherichia coli, we confirmed that nearly all types of feed-forward loop were significantly overrepresented in the bacterial network. We then used mathematical modeling to study their dynamics by manipulating the rise times of the top-level protein concentration, termed the induction time, through alteration of the protein destruction rates. Rise times of the regulated proteins exhibited two qualitatively different regimes, depending on whether top-level inductions were "fast" or "slow." In the fast regime, rise times were nearly independent of rapid top-level inductions, indicative of biological robustness, and occurred when RNA production rate-limits the protein yield. Alternatively, the protein rise times were dependent upon slower top-level inductions, greater than approximately one bacterial cell cycle. An equation is given for this crossover, which depends upon three parameters of the direct-regulatory path: transcriptional cooperation at the DNA-binding site, a protein-DNA dissociation constant, and the relative magnitude of the top-level protien concentration.

  9. Evidence of wave front folding of sonic booms by a laboratory-scale deterministic experiment of shock waves in a heterogeneous medium.

    PubMed

    Ganjehi, Lili; Marchiano, Régis; Coulouvrat, François; Thomas, Jean-Louis

    2008-07-01

    The influence of the planetary boundary layer on the sonic boom received at the ground level is known since the 1960s to be of major importance. Sonic boom propagation in a turbulent medium is characterized by an increase of the mean rise time and a huge variability. An experiment is conducted at a 1:100,000 scale in water to investigate ultrasonic shock wave interaction with a single heterogeneity. The experiment shows a very good scaling with sonic boom, concerning the size of the heterogeneities, the wave amplitude, and the rise time of the incident wave. The wave front folding associated with local focusing, and its link to the increase of the rise time, are evidenced by the experiment. The observed amplification of the peak pressure (by a factor up to 2), and increase of the rise time (by up to about one magnitude order), are in qualitative agreement with sonic boom observations. A nonlinear parabolic model is compared favorably to the experiment on axis, though the paraxial approximation turns out less precise off axis. Simulations are finally used to discriminate between nonlinear and linear propagations, showing nonlinearities affect mostly the higher harmonics that are in the audible range for sonic booms. PMID:18646955

  10. Basic Auditory Processing and Developmental Dyslexia in Chinese

    ERIC Educational Resources Information Center

    Wang, Hsiao-Lan Sharon; Huss, Martina; Hamalainen, Jarmo A.; Goswami, Usha

    2012-01-01

    The present study explores the relationship between basic auditory processing of sound rise time, frequency, duration and intensity, phonological skills (onset-rime and tone awareness, sound blending, RAN, and phonological memory) and reading disability in Chinese. A series of psychometric, literacy, phonological, auditory, and character…

  11. Heat profiling of phacoemulsification tip using a thermal scanning camera.

    PubMed

    Ngo, Wei Kiong; Lim, Louis W; Tan, Colin S H; Heng, Wee Jin

    2013-12-01

    An experimental study to measure the heat profile of the phacoemulsification (phaco) tip using standard continuous phaco and hyperpulse phaco with and without waveform power modulation in the Millennium Microsurgical System with Custom Control Software (CCS). The phaco tip was imaged in air using a thermal camera. The highest temperature was measured 15 s after application of phaco power. Continuous, hyperpulse and waveform power modulations of the Millennium Microsurgical System were used with different power settings (20, 50 and 100 %) and duty cycles (40, 60 and 90 %), with the irrigation turned on and off. Using continuous phaco with the irrigation on, the phaco tip temperature remains <28.0 °C. With irrigation off, the temperature is higher compared to irrigation on but still remains <45.0 °C. Comparing the temperatures for all three power modulations when irrigation is on, at each phaco power and duty cycle setting, the temperature of the phaco tip is highest with continuous phaco, followed by hyperpulse with rise time 1, then hyperpulse with rise time 2. When irrigation is off, the highest temperatures are recorded using the hyperpulse with rise time 2, followed by continuous phaco, then hyperpulse with rise time 1. Hyperpulse and waveform modulations reduce heat generation compared to the continuous mode when irrigation is turned on. Lower duty cycles and lower ultrasound power produce less heat at the phaco tip.

  12. GaAlAs laser temperature effects on the BER performance of a gigabit PCM fiber system. [Bit Error Rate

    NASA Technical Reports Server (NTRS)

    Eng, S. T.; Bergman, L. A.

    1982-01-01

    The performance of a gigabit pulse-code modulation fiber system has been investigated as a function of laser temperature. The bit error rate shows an improvement for temperature in the range of -15 C to -35 C. A tradeoff seems possible between relaxation oscillation, rise time, and signal-to-noise ratio.

  13. VizieR Online Data Catalog: 10yr of Swift/XRT obs. of GRBs (Yi+, 2016)

    NASA Astrophysics Data System (ADS)

    Yi, S.-X.; Xi, S.-Q.; Yu, H.; Wang, F. Y.; Mu, H.-J.; Lu, L.-Z.; Liang, E.-W.

    2016-07-01

    In this paper, we analyze the X-ray flare data of Swift/XRT over 10yrs until the end of 2015 March, and study the distributions of energy, duration, waiting time, rise time, decay time, peak time, and peak flux. (1 data file).

  14. Auditory Processing in Specific Language Impairment (SLI): Relations with the Perception of Lexical and Phrasal Stress

    ERIC Educational Resources Information Center

    Richards, Susan; Goswami, Usha

    2015-01-01

    Purpose: We investigated whether impaired acoustic processing is a factor in developmental language disorders. The amplitude envelope of the speech signal is known to be important in language processing. We examined whether impaired perception of amplitude envelope rise time is related to impaired perception of lexical and phrasal stress in…

  15. A DISCUS EMP simulator design for long narrow buried objects

    SciTech Connect

    van Lint, V.A.J.; Berger, R.A.; Crevier, W.; Dancz, J.; Naff, T.; Pettus, E.; Stettner, R.

    1982-12-01

    A Distributed Source Conducting Medium Underground System (DISCUS) Simulator concept to provide both fast rise time and late time EMP excitation is presented. An early time module has been constructed and tested. Calculations of the electric and magnetic fields for this single prototype are compared with experimental measurements.

  16. Low-power integrated-circuit driver for ferrite-memory word lines

    NASA Technical Reports Server (NTRS)

    Katz, S.

    1970-01-01

    Composite circuit uses both n-p-n bipolar and p-channel MOS transistors /BIMOS/. The BIMOS driver provides 1/ ease of integrated circuit construction, 2/ low standby power consumption, 3/ bidirectional current pulses, and 4/ current-pulse amplitudes and rise times independent of active device parameters.

  17. Daily activities and sleep quality in college students.

    PubMed

    Carney, Colleen E; Edinger, Jack D; Meyer, Björn; Lindman, Linda; Istre, Tai

    2006-01-01

    There is growing evidence that social rhythms (e.g., daily activities such as getting into or out of bed, eating, and adhering to a work schedule) have important implications for sleep. The present study used a prospective measure of daily activities to assess the relation between sleep and social rhythms. College students (n=243) 18 to 39 yrs of age, completed the Social Rhythm Metric (SRM) each day for 14 d and then completed the Pittsburgh Sleep Quality Index (PSQI). The sample was divided into groups of good or poor sleepers, according to a PSQI cut-off score of 5 points and was compared on the regularity, frequency, timing, and extent of social engagement during activities. There was a lower frequency and less regularity of social rhythms in poor sleepers relative to good sleepers. Good sleepers engaged more regularly in activities with active social engagement. Earlier rise time, first consumption of a beverage, going outdoors for the first time, and bedtime were associated with better sleep. Greater variability in rise time, consuming a morning beverage, returning home for the last time, and bedtime were associated with more disturbed sleep. The results are consistent with previous findings of reduced regularity in bedtime and rise time schedules in undergraduates, other age groups, and in clinical populations. Results augment the current thought that regulating behavioral zeitgebers may be important in influencing bed and rise times, and suggest that engaging in activities with other people may increase regularity.

  18. Statistical aspects of solar flares

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    1987-01-01

    A survey of the statistical properties of 850 H alpha solar flares during 1975 is presented. Comparison of the results found here with those reported elsewhere for different epochs is accomplished. Distributions of rise time, decay time, and duration are given, as are the mean, mode, median, and 90th percentile values. Proportions by selected groupings are also determined. For flares in general, mean values for rise time, decay time, and duration are 5.2 + or - 0.4 min, and 18.1 + or 1.1 min, respectively. Subflares, accounting for nearly 90 percent of the flares, had mean values lower than those found for flares of H alpha importance greater than 1, and the differences are statistically significant. Likewise, flares of bright and normal relative brightness have mean values of decay time and duration that are significantly longer than those computed for faint flares, and mass-motion related flares are significantly longer than non-mass-motion related flares. Seventy-three percent of the mass-motion related flares are categorized as being a two-ribbon flare and/or being accompanied by a high-speed dark filament. Slow rise time flares (rise time greater than 5 min) have a mean value for duration that is significantly longer than that computed for fast rise time flares, and long-lived duration flares (duration greater than 18 min) have a mean value for rise time that is significantly longer than that computed for short-lived duration flares, suggesting a positive linear relationship between rise time and duration for flares. Monthly occurrence rates for flares in general and by group are found to be linearly related in a positive sense to monthly sunspot number. Statistical testing reveals the association between sunspot number and numbers of flares to be significant at the 95 percent level of confidence, and the t statistic for slope is significant at greater than 99 percent level of confidence. Dependent upon the specific fit, between 58 percent and 94 percent of

  19. Influence of positive slopes on ultrafast heating in an atmospheric nanosecond-pulsed plasma synthetic jet

    NASA Astrophysics Data System (ADS)

    Zhu, Yifei; Wu, Yun; Jia, Min; Liang, Hua; Li, Jun; Li, Yinghong

    2015-02-01

    The influence of positive slopes on the energy coupling and hydrodynamic responses in an atmospheric nanosecond-pulsed plasma synthetic jet (PSJ) was investigated using a validated dry air plasma kinetics model. Based on a 1D simulation of the energy transfer mechanism in ultrafast gas heating, and with reasonable simplification, a 2D model of a PSJ was developed to investigate the discharge characteristics and hydrodynamic responses under different rise times. In the 1D simulation, a shorter voltage rise time results in a higher electric field in less time, reduces the time of ionization front propagation and produces stronger ionization. The energy transfer efficiency of ultrafast heating is approximately 60% but a steeper positive slope could raise local heating power density and make input energy 77% higher at the cost of 2.4% lower energy transfer efficiency under the same voltage amplitude and pulse width. The quench heating power density is always 27-30 times higher than that of ion collision in most discharge regions, while ion collision heating power density is 10-103 times higher in the sheath region. In 2D PSJ simulation, spatial-temporal distribution of electron density, reduced electric field and deposited energy were calculated for the first time. Heating energy increases sharply with voltage rise time decrease in the time scale of 20-50 ns. Jet velocity increases by 100 m s-1 when the rise time is reduced by 20 ns. A shorter voltage rise time also leads to higher orifice pressure and temperature, but their peak values are limited by the structure of the orifice and the discharge cavity.

  20. 40Ar/39Ar age of the Manson impact structure, Iowa, and correlative impact ejecta in the Crow Creek member of the Pierre Shale (Upper Cretaceous), South Dakota and Nebraska

    USGS Publications Warehouse

    Izett, G.A.; Cobban, W.A.; Dalrymple, G.B.; Obradovich, J.D.

    1998-01-01

    A set of 34 laser total-fusion 40Ar/39Ar analyses of sanidine from a melt layer in crater-fill deposits of the Manson impact structure in Iowa has a weighted-mean age of 74.1 ?? 0.1 Ma. This age is about 9.0 m.y. older than 40Ar/39Ar ages of shocked microcline from the Manson impact structure reported previously by others. The 74.1 Ma age of the sanidine, which is a melt product of Precambrian microcline clasts, indicates that the Manson impact structure played no part in the Cretaceous-Tertiary (K-T) mass extinction at 64.5 Ma. Moreover, incremental-heating 40Ar/39Ar ages of the sanidine show that it is essentially free of excess 40Ar and has not been influenced by postcrystallization heating or alteration. An age spectrum of the matrix of the melt layer shows effects of 39Ar recoil, including older ages in the low-temperature increments and younger ages in the high-temperature increments. At 17 places in eastern South Dakota and Nebraska, shocked quartz and feldspar grains are concentrated in the lower part of the Crow Creek Member of the Pierre Shale (Upper Cretaceous). The grains are largest (3.2 mm) in southeastern South Dakota and decrease in size (0.45 mm) to the northwest, consistent with the idea that the Manson impact structure was their source. The ubiquitous presence of shocked grains concentrated in a thin calcarenite at the base of the Crow Creek Member suggests it is an event bed recording an instant of geologic time. Ammonites below and above the Crow Creek Member limit its age to the zone of Didymoceras nebrascense of earliest late Campanian age. Plagioclase from a bentonite bed in this zone in Colorado has a 40Ar/39Ar age of 74.1 ?? 0.1 Ma commensurate with our sanidine age of 74.1 Ma for the Manson impact structure. 40Ar/39Ar ages of bentonite beds below and above the Crow Creek are consistent with our 74.1 ?? 0.1 Ma age for the Manson impact structure and limit its age to the interval ?? 74.5 0.1 to 73.8 ?? 0.1 Ma. Recently, two origins for the

  1. Dynamic NBTI effects in HfSiON.

    SciTech Connect

    Devine, Roderick A. B.; Kambour, Kenneth E.; Hjalmarson, Harold Paul; Mee, Jesse K.

    2010-12-01

    between 'bursts' of AC stress cycles, the I{sub ds}(V{sub gs}) characteristic in the range (-0.6V, -1.3V) was measured in 10.2 {micro}s. V{sub th} was extracted directly from this curve, or from a single I{sub ds} point normalized to the initial I{sub ds}{sup o} using our previous method. The resulting I{sub ds}/I{sub ds}{sup o} curves are compared; in Fig 2, the continuous stress results are included. In the second method, we examined the recovery dynamic by holding V{sub gs} = 0V for a finite amount of time (range 100 ns to 100 ms) following stress at V{sub gs} = - 2V for various times. In Fig 3 we compare |{Delta}V{sub th}(t)| results for recovery times of 100ms, 1ms, 100{micro}s, 50{micro}s, 25{micro}s, 10{micro}s, 100ns, and DC (i.e. no recovery) The data in Fig 2 shows that with a high frequency stress (2.5MHz) devices undergo significantly less (but finite) current degradation than devices stressed at 10Hz. This appears to be limited by charging and not by recovery. Fig 3 supports this hypothesis since for 100ns recovery periods, only a small percentage of the trapped charge relaxes. Detailed explanation of these experiments will be presented at the conference.

  2. DETECTING MASSIVE GRAVITONS USING PULSAR TIMING ARRAYS

    SciTech Connect

    Lee, Kejia; Kramer, Michael; Jenet, Fredrick A.; Price, Richard H.; Wex, Norbert

    2010-10-20

    At the limit of weak static fields, general relativity becomes Newtonian gravity with a potential field that falls off as inverse distance rather than a theory of Yukawa-type fields with a finite range. General relativity also predicts that the speed of disturbances of its waves is c, the vacuum light speed, and is non-dispersive. For these reasons, the graviton, the boson for general relativity, can be considered to be massless. Massive gravitons, however, are features of some alternatives to general relativity. This has motivated experiments and observations that, so far, have been consistent with the zero-mass graviton of general relativity, but further tests will be valuable. A basis for new tests may be the high sensitivity gravitational wave (GW) experiments that are now being performed and the higher sensitivity experiments that are being planned. In these experiments, it should be feasible to detect low levels of dispersion due to non-zero graviton mass. One of the most promising techniques for such a detection may be the pulsar timing program that is sensitive to nano-Hertz GWs. Here, we present some details of such a detection scheme. The pulsar timing response to a GW background with the massive graviton is calculated, and the algorithm to detect the massive graviton is presented. We conclude that, with 90% probability, massless gravitons can be distinguished from gravitons heavier than 3 x 10{sup -22} eV (Compton wavelength {lambda}{sub g} = 4.1 x 10{sup 12} km), if bi-weekly observation of 60 pulsars is performed for 5 years with a pulsar rms timing accuracy of 100 ns. If 60 pulsars are observed for 10 years with the same accuracy, the detectable graviton mass is reduced to 5 x 10{sup -23} eV ({lambda}{sub g} = 2.5 x 10{sup 13} km); for 5 year observations of 100 or 300 pulsars, the sensitivity is respectively 2.5 x 10{sup -22} ({lambda}{sub g} = 5.0 x 10{sup 12} km) and 10{sup -22} eV ({lambda}{sub g} = 1.2 x 10{sup 13} km). Finally, a 10 year

  3. Antenna induced hot restrike of a ceramic metal halide lamp recorded by high-speed photography

    NASA Astrophysics Data System (ADS)

    Hermanns, P.; Hoebing, T.; Bergner, A.; Ruhrmann, C.; Awakowicz, P.; Mentel, J.

    2016-03-01

    The hot restrike is one of the biggest challenges in operating ceramic metal halide lamps with mercury as buffer gas. Compared to a cold lamp, the pressure within a ceramic burner is two orders of magnitude higher during steady state operation due to the high temperature of the ceramic tube and the resulting high mercury vapour pressure. Room temperature conditions are achieved after 300 s of cooling down in a commercial burner, enclosed in an evacuated outer bulb. At the beginning of the cooling down, ignition voltage rises up to more than 14 kV. A significant reduction of the hot-restrike voltage can be achieved by using a so called active antenna. It is realized by a conductive sleeve surrounding the burner at the capillary of the upper electrode. The antenna is connected to the lower electrode of the lamp, so that its potential is extended to the vicinity of the upper electrode. An increased electric field in front of the upper electrode is induced, when an ignition pulse is applied to the lamp electrodes. A symmetrically shaped ignition pulse is applied with an amplitude, which is just sufficient to re-ignite the hot lamp. The re-ignition, 60 s after switching off the lamp, when the mercury pressure starts to be saturated, is recorded for both polarities of the ignition pulse with a high-speed camera, which records four pictures within the symmetrically shaped ignition pulse with exposure times of 100 ns and throws of 100 ns. The pictures show that the high electric field and its temporal variation establish a local dielectric barrier discharge in front of the upper electrode inside the burner, which covers the inner wall of the burner with a surface charge. It forms a starting point of streamers, which may induce the lamp ignition predominantly within the second half cycle of the ignition pulse. It is found out that an active antenna is more effective when the starting point of the surface streamer in front of the sleeve is a negative surface charge on the

  4. Compact Short-Pulsed Electron Linac Based Neutron Sources for Precise Nuclear Material Analysis

    NASA Astrophysics Data System (ADS)

    Uesaka, M.; Tagi, K.; Matsuyama, D.; Fujiwara, T.; Dobashi, K.; Yamamoto, M.; Harada, H.

    2015-10-01

    An X-band (11.424GHz) electron linac as a neutron source for nuclear data study for the melted fuel debris analysis and nuclear security in Fukushima is under development. Originally we developed the linac for Compton scattering X-ray source. Quantitative material analysis and forensics for nuclear security will start several years later after the safe settlement of the accident is established. For the purpose, we should now accumulate more precise nuclear data of U, Pu, etc., especially in epithermal (0.1-10 eV) neutrons. Therefore, we have decided to modify and install the linac in the core space of the experimental nuclear reactor "Yayoi" which is now under the decommission procedure. Due to the compactness of the X-band linac, an electron gun, accelerating tube and other components can be installed in a small space in the core. First we plan to perform the time-of-flight (TOF) transmission measurement for study of total cross sections of the nuclei for 0.1-10 eV energy neutrons. Therefore, if we adopt a TOF line of less than 10m, the o-pulse length of generated neutrons should be shorter than 100 ns. Electronenergy, o-pulse length, power, and neutron yield are ~30 MeV, 100 ns - 1 micros, ~0.4 kW, and ~1011 n/s (~103 n/cm2/s at samples), respectively. Optimization of the design of a neutron target (Ta, W, 238U), TOF line and neutron detector (Ce:LiCAF) of high sensitivity and fast response is underway. We are upgrading the electron gun and a buncher to realize higher current and beam power with a reasonable beam size in order to avoid damage of the neutron target. Although the neutron flux is limited in case of the X-band electron linac based source, we take advantage of its short pulse aspect and availability for nuclear data measurement with a short TOF system. First, we form a tentative configuration in the current experimental room for Compton scattering in 2014. Then, after the decommissioning has been finished, we move it to the "Yayoi" room and perform

  5. NMR assignments of the N-terminal domain of Nephila clavipes spidroin 1

    PubMed Central

    Parnham, Stuart; Gaines, William A.; Duggan, Brendan M.; Marcotte, William R.

    2011-01-01

    The building blocks of spider dragline silk are two fibrous proteins secreted from the major ampullate gland named spidroins 1 and 2 (MaSp1, MaSp2). These proteins consist of a large central domain composed of approximately 100 tandem copies of a 35–40 amino acid repeat sequence. Non-repetitive N and C-terminal domains, of which the C-terminal domain has been implicated to transition from soluble and insoluble states during spinning, flank the repetitive core. The N-terminal domain until recently has been largely unknown due to difficulties in cloning and expression. Here, we report nearly complete assignment for all 1H, 13C, and 15N resonances in the 14 kDa N-terminal domain of major ampullate spidroin 1 (MaSp1-N) of the golden orb-web spider Nephila clavipes. PMID:21152998

  6. Protein molecular data from ancient (>1 million years old) fossil material: pitfalls, possibilities and grand challenges.

    PubMed

    Schweitzer, Mary Higby; Schroeter, Elena R; Goshe, Michael B

    2014-07-15

    Advances in resolution and sensitivity of analytical techniques have provided novel applications, including the analyses of fossil material. However, the recovery of original proteinaceous components from very old fossil samples (defined as >1 million years (1 Ma) from previously named limits in the literature) is far from trivial. Here, we discuss the challenges to recovery of proteinaceous components from fossils, and the need for new sample preparation techniques, analytical methods, and bioinformatics to optimize and fully utilize the great potential of information locked in the fossil record. We present evidence for survival of original components across geological time, and discuss the potential benefits of recovery, analyses, and interpretation of fossil materials older than 1 Ma, both within and outside of the fields of evolutionary biology.

  7. Geology, age, and tectonic setting of the Cretaceous Sliderock Mountain Volcano, Montana

    USGS Publications Warehouse

    Du Bray, E.A.; Harlan, Stephen S.

    1998-01-01

    The Sliderock Mountain stratovolcano, part of the Upper Cretaceous continental magmatic arc in southwestern Montana, consists of volcaniclastic strata and basaltic andesite lava flows. An intrusive complex represents the volcano's solidified magma chamber. Compositional diversity within components of the volcano appears to reflect evolution via about 50 percent fractional crystallization involving clinopyroxene and plagioclase. 40Ar/39Ar indicate that the volcano was active about 78?1 Ma.

  8. Long Term Trends in Subantarctic Nutrient Consumption: Evidence from Sedimentary and Diatom-Bound Nitrogen Isotopes

    NASA Astrophysics Data System (ADS)

    Bedsole, P.

    2014-12-01

    It has been proposed that the long term increase in Subantarctic opal export during glacial periods, centered around 1 Ma, is related to enhanced iron deposition and, potentially, carbon dioxide drawdown. New bulk sedimentary and diatom-bound nitrogen isotope records are used in combination with opal accumulation data from ODP Site 1090 to investigate controls on export production over the last 3 Ma. Sedimentary nitrogen content tracks opal during periods of high iron accumulation, especially after ~1 Ma. Bulk sedimentary nitrogen isotope trends are negatively correlated with sedimentary N-content and opal accumulation. This may be signal weaker nutrient consumption during times of high production, perhaps as a result of enhanced vertical nutrient supply. Alternatively, this variation in bulk, where high values occur in organic poor intervals, is consistent with other evidence for nitrogen isotopic alteration during periods of low export to the seafloor. The diatom-bound nitrogen isotope record does not have a clear relationship with opal or iron accumulation. A long term shift in the diatom-bound N isotope values is apparent, where the average diatom-bound δ15N from 0.5-1 Ma is 4.4 ‰, and from 2-2.6 Ma is 5.9 ‰. This decrease may reflect long-term changes in nitrate availability. A first order comparison to planktonic/benthic carbon isotopic gradients suggests that enhanced vertical mixing may explain the observed productivity peaks and lower overall diatom-bound N isotope values in the interval centered around 1 Ma.

  9. Chronotype, bed timing and total sleep time in seniors.

    PubMed

    Monk, Timothy H; Buysse, Daniel J

    2014-06-01

    Many older adults (seniors) experience problems with getting enough sleep. Because of the link between sleep and circadian rhythms, changes in bedtime lead to changes in the amount of sleep obtained. Although primarily determined genetically, chronotype changes with advancing age towards a more morning-type (M-type) orientation. In a 2006 study, we have found a linear relationship, by which the earlier a senior's bedtime, the more sleep she/he will obtain. The aim of this study was to see whether this relationship differs for M-type seniors, as compared to seniors outside the M-type category. Retired seniors (n = 954, 535 M, 410F, 65 years+, mean age 74.4 years) taking part in a telephone interview were divided into M-types and Other types (O-types) using the Composite Scale of Morningness (CSM). The relationship between bedtime and Total Sleep Time (TST), and between rise-time and TST, was tested using linear regression separately for M-types and O-types. For each participant, habitual bedtime, rise-time and total Sleep Time (TST) [after removing time spent in unwanted wakefulness] were obtained using a telephone version of the Sleep Timing Questionnaire (STQ). Both chronotype groups showed a significant linear relationship between bedtime and TST (p < 0.001); with earlier bedtimes leading to more TST (M-type 5.6 min; O-type 4.4 min per 10 min change [slope difference p = 0.05]); and an opposite relationship between rise-time and TST with earlier rise-times leading to less TST (M-type 6.7 min; O-type 4.2 min per 10 min change [slope difference p = 0.001]). M-types retired to bed 56 min earlier (p < 0.001), awoke 93 min earlier (p < 0.001) and obtained 23 min less TST (p < 0.001) than O-types. In conclusion, both chronotypes showed TST to be related in a linear way to bedtime and rise-time; the overall shorter TST in M-types was due to them rising 93 min earlier, but only retiring to bed 56 min earlier than O

  10. Exposure history of the lunar meteorite, Elephant Moraine 87521

    NASA Technical Reports Server (NTRS)

    Vogt, S.; Herzog, G. F.; Eugster, O.; Michel, TH.; Niedermann, S.; Kraehenbuhl, U.; Middleton, R.; Dezfouly-Arjomandy, B.; Fink, D.; Klein, J.

    1993-01-01

    We report the noble gas concentrations and the Al-26, Be-10, Cl-36, and Ca-41 activities of the Antarctic lunar meteorite Elephant Moraine 87521. Although the actual exposure history of the meteorite may have been more complex, the following model history accounts satisfactorily for the cosmogenic nuclide data: A first stage of lunar irradiation for about 1 Ma at a depth of 1-5 g/sq cm followed, not necessarily directly, by a second one for 26 Ma at about 565 g/sq cm; launch from the moon less than 0.1 Ma ago; and arrival on earth 15-50 ka ago. The small concentration of trapped gases shows that except for some material that may have been introduced at the moment of launch, EET 87521 spent less than 1 Ma at a lunar depth less than 1 g/sq cm. EET 87521 has a K/Ar age in the range 3.0-3.4 Ga, which is typical for lunar mare basalts.

  11. Spatial variations in focused exhumation along a continental-scale strike-slip fault: The Denali fault of the eastern Alaska Range

    USGS Publications Warehouse

    Benowitz, J.A.; Layer, P.W.; Armstrong, P.; Perry, S.E.; Haeussler, P.J.; Fitzgerald, P.G.; VanLaningham, S.

    2011-01-01

    40Ar/39Ar, apatite fission-track, and apatite (U-Th)/He thermochronological techniques were used to determine the Neogene exhumation history of the topographically asymmetric eastern Alaska Range. Exhumation cooling ages range from ~33 Ma to ~18 Ma for 40Ar/39Ar biotite, ~18 Ma to ~6 Ma for K-feldspar minimum closure ages, and ~15 Ma to ~1 Ma for apatite fission-track ages, and apatite (U-Th)/He cooling ages range from ~4 Ma to ~1 Ma. There has been at least ~11 km of exhumation adjacent to the north side of Denali fault during the Neogene inferred from biotite 40Ar/39Ar thermochronology. Variations in exhumation history along and across the strike of the fault are influenced by both far-field effects and local structural irregularities. We infer deformation and rapid exhumation have been occurring in the eastern Alaska Range since at least ~22 Ma most likely related to the continued collision of the Yakutat microplate with the North American plate. The Nenana Mountain region is the late Pleistocene to Holocene (~past 1 Ma) primary locus of tectonically driven exhumation in the eastern Alaska Range, possibly related to variations in fault geometry. During the Pliocene, a marked increase in climatic instability and related global cooling is temporally correlated with an increase in exhumation rates in the eastern Alaska Range north of the Denali fault system.

  12. Arctic Dinoflagellate Migration Marks the Oligocene Glacial Maximum: Implications for the Rupelian-Chattian Boundary

    NASA Astrophysics Data System (ADS)

    van Simaeys, S.; Brinkhuis, H.; Pross, J.; Williams, G. L.; Zachos, J. C.

    2004-12-01

    Various geochemical and biotic climate proxies, and notably deep-sea benthic foraminiferal δ 18O records indicate that the Eocene 'greenhouse' state of the Earth gradually evolved towards an earliest Oligocene 'icehouse' state, eventually triggering the abrupt appearance of large continental ice-sheets on Antarctic at ˜33.3 Ma (Oi-1 event). This, however, was only the first of two major glacial events in the Oligocene. Benthic foraminiferal δ 18O records show a second positive excursion in the mid Oligocene, consistent with a significant ice-sheet expansion and/or cooling at 27.1 Ma (Oi-2b) coincident with magnetosubchron C9n. Here, we report on a mid Oligocene, globally synchronous, Arctic dinoflagellate migration event, calibrated against the upper half of C9n. A sudden appearance, and abundance increases of the Arctic taxon Svalbardella at lower-middle latitudes coincides with the so-called Oi-2b benthic δ 18O event, dated at ˜27.1 Ma. This phenomenon is taken to indicate significant high-latitude surface water cooling, concomitant Antarctic ice-sheet growth, and sea level lowering. The duration of the Svalbardella migrations, and the episode of profound cooling is estimated as ˜500 ka, and is here termed the Oligocene Glacial Maximum (OGM). Our records suggest a close link between the OGM, sea-level fall, and the classic Rupelian-Chattian boundary, magnetostratigraphically dating this boundary as ˜27.1 Ma.

  13. K?Ar dating and geological significance of clastic sediments of the Paleocene Sepultura Formation, Baja California, México

    NASA Astrophysics Data System (ADS)

    Téllez Duarte, Miguel Agustín.; López Martínez, Margarita

    2002-12-01

    At its type locality, the Paleocene Sepultura Formation consists of two members: a lower glauconitic-rich clastic section and an upper calcareous section. Three samples of authigenic glauconite pellets from two localities with good clastic sediment exposures were dated using K-Ar. At the type locality of Mesa La Sepultura, pellets from the middle of the clastic section yield a date of 60±1 Ma (weighted average of four experiments), and pellets from the top of the clastic unit give a date of 60±1 Ma (weighted average of two experiments). Pellets from the base of the section at La Mesa, 60 km distant, give a date of 59±1 Ma (one experiment). Dates obtained are in good agreement with those reported by biostratigraphy and confirm a Late Danian age. Our results differ from those reported elsewhere, in which low potassium content glauconites yield younger K-Ar ages than expected. An explanation for our observed agreement in ages could be related to the tectonic setting of forearc basins, where the low geothermal gradient prevents argon loss and reliable dates can be obtained.

  14. Sorghum Phytochrome B Inhibits Flowering in Long Days by Activating Expression of SbPRR37 and SbGHD7, Repressors of SbEHD1, SbCN8 and SbCN12

    PubMed Central

    Yang, Shanshan; Murphy, Rebecca L.; Morishige, Daryl T.; Klein, Patricia E.; Rooney, William L.; Mullet, John E.

    2014-01-01

    Light signaling by phytochrome B in long days inhibits flowering in sorghum by increasing expression of the long day floral repressors PSEUDORESPONSE REGULATOR PROTEIN (SbPRR37, Ma1) and GRAIN NUMBER, PLANT HEIGHT AND HEADING DATE 7 (SbGHD7, Ma6). SbPRR37 and SbGHD7 RNA abundance peaks in the morning and in the evening of long days through coordinate regulation by light and output from the circadian clock. 58 M, a phytochrome B deficient (phyB-1, ma3R) genotype, flowered ∼60 days earlier than 100 M (PHYB, Ma3) in long days and ∼11 days earlier in short days. Populations derived from 58 M (Ma1, ma3R, Ma5, ma6) and R.07007 (Ma1, Ma3, ma5, Ma6) varied in flowering time due to QTL aligned to PHYB/phyB-1 (Ma3), Ma5, and GHD7/ghd7-1 (Ma6). PHYC was proposed as a candidate gene for Ma5 based on alignment and allelic variation. PHYB and Ma5 (PHYC) were epistatic to Ma1 and Ma6 and progeny recessive for either gene flowered early in long days. Light signaling mediated by PhyB was required for high expression of the floral repressors SbPRR37 and SbGHD7 during the evening of long days. In 100 M (PHYB) the floral activators SbEHD1, SbCN8 and SbCN12 were repressed in long days and de-repressed in short days. In 58 M (phyB-1) these genes were highly expressed in long and short days. Furthermore, SbCN15, the ortholog of rice Hd3a (FT), is expressed at low levels in 100 M but at high levels in 58 M (phyB-1) regardless of day length, indicating that PhyB regulation of SbCN15 expression may modify flowering time in a photoperiod-insensitive manner. PMID:25122453

  15. Sorghum phytochrome B inhibits flowering in long days by activating expression of SbPRR37 and SbGHD7, repressors of SbEHD1, SbCN8 and SbCN12.

    PubMed

    Yang, Shanshan; Murphy, Rebecca L; Morishige, Daryl T; Klein, Patricia E; Rooney, William L; Mullet, John E

    2014-01-01

    Light signaling by phytochrome B in long days inhibits flowering in sorghum by increasing expression of the long day floral repressors PSEUDORESPONSE REGULATOR PROTEIN (SbPRR37, Ma1) and GRAIN NUMBER, PLANT HEIGHT AND HEADING DATE 7 (SbGHD7, Ma6). SbPRR37 and SbGHD7 RNA abundance peaks in the morning and in the evening of long days through coordinate regulation by light and output from the circadian clock. 58 M, a phytochrome B deficient (phyB-1, ma3R) genotype, flowered ∼60 days earlier than 100 M (PHYB, Ma3) in long days and ∼11 days earlier in short days. Populations derived from 58 M (Ma1, ma3R, Ma5, ma6) and R.07007 (Ma1, Ma3, ma5, Ma6) varied in flowering time due to QTL aligned to PHYB/phyB-1 (Ma3), Ma5, and GHD7/ghd7-1 (Ma6). PHYC was proposed as a candidate gene for Ma5 based on alignment and allelic variation. PHYB and Ma5 (PHYC) were epistatic to Ma1 and Ma6 and progeny recessive for either gene flowered early in long days. Light signaling mediated by PhyB was required for high expression of the floral repressors SbPRR37 and SbGHD7 during the evening of long days. In 100 M (PHYB) the floral activators SbEHD1, SbCN8 and SbCN12 were repressed in long days and de-repressed in short days. In 58 M (phyB-1) these genes were highly expressed in long and short days. Furthermore, SbCN15, the ortholog of rice Hd3a (FT), is expressed at low levels in 100 M but at high levels in 58 M (phyB-1) regardless of day length, indicating that PhyB regulation of SbCN15 expression may modify flowering time in a photoperiod-insensitive manner. PMID:25122453

  16. The End of Monterey Submarine Canyon Incision and Potential River Source Areas-Os, Nd, and Pb Isotope Constraints from Hydrogenetic Fe-Mn Crusts

    NASA Astrophysics Data System (ADS)

    Conrad, T. A.; Nielsen, S.; Ehrenbrink, B. P. E.; Blusztajn, J.; Hein, J. R.; Paytan, A.

    2015-12-01

    The Monterey Canyon off central California is the largest submarine canyon off North America and is comparable in scale to the Grand Canyon. The age and history of the Monterey Canyon are poorly constrained due to thick sediment cover and sediment disruption from turbidity currents. To address this deficit we analyzed isotopic proxies (Os, Pb, Nd) from hydrogenetic ferromanganese (Fe-Mn) crusts, which grow over millions of years on elevated rock surfaces by precipitation of metals from seawater. Fe-Mn crusts were studied from Davidson Seamount near the base of the Monterey submarine fan, the Taney Seamount Chain, and from Hoss Seamount, which serves as a regional control (Fig.). Fe-Mn crusts were dated using Os isotope ratios compared to those that define the Cenozoic Os isotope seawater curve. Four Fe-Mn crust samples from Davidson and Taney Seamounts deviate from the Os isotopic seawater curve towards radiogenic values after 4.5±1 Ma. Osmium is well mixed in the global ocean and is not subject to significant diffusive reequilibration in Fe-Mn crusts. We therefore attribute deviations from the Os isotope seawater curve to large-scale terrestrial input that ended about 4.5±1 Ma. The two Davidson samples also show more radiogenic Nd isotope values from about 4.5±1 Ma. Lead isotopes in one Davidson Seamount crust, measured by LA-ICPMS, deviate from regional values after 4.5±1 Ma for about 500 ka towards terrestrial sources. The Taney Seamount Fe-Mn crust does not deviate from regional Nd nor Pb isotope values due to its greater distance from Monterey Canyon and the shorter marine residence times of Nd and Pb. Isotope plots of our crust data and compiled data for potential source rocks indicate that the river that carved Monterey Canyon carried sediment with values closer to the Sierra Nevada than to a Colorado Plateau source, with cessation of major riverine input occurring approximately 4.5±1 Ma, an age that we interpret as the end of the Monterey Canyon

  17. Comparing an optical parametric oscillator (OPO) as a viable alternative for mid-infrared tissue ablation with a free electron laser (FEL).

    PubMed

    Mackanos, Mark A; Simanovskii, Dmitrii M; Contag, Christopher H; Kozub, John A; Jansen, E Duco

    2012-11-01

    Beneficial medical laser ablation removes material efficiently with minimal collateral damage. A Mark-III free electron laser (FEL), at a wavelength of 6.45 μm has demonstrated minimal damage and high ablation yield in ocular and neural tissues. While this wavelength has shown promise for surgical applications, further advances are limited by the high overhead for FEL use. Alternative mid-infrared sources are needed for further development. We compared the FEL with a 5-μs pulse duration with a Q-switched ZGP-OPO with a 100-ns pulse duration at mid-infrared wavelengths. There were no differences in the ablation threshold of water and mouse dermis with these two sources in spite of the difference in their pulse structures. There was a significant difference in crater depth between the ZGP:OPO and the FEL. At 6.1 μm, the OPO craters are eight times the depth of the FEL craters. The OPO craters at 6.45 and 6.73 μm were six and five times the depth of the FEL craters, respectively. Bright-field (pump-probe) images showed the classic ablation mechanism from formation of a plume through collapse and recoil. The crater formation, ejection, and collapse phases occurred on a faster time-scale with the OPO than with the FEL. This research showed that a ZGP-OPO laser could be a viable alternative to FEL for clinical applications. PMID:22278348

  18. Effect of Electrical Stimulation on Fruit Body Formation in Cultivating Mushrooms

    PubMed Central

    Takaki, Koichi; Yoshida, Kohei; Saito, Tatsuya; Kusaka, Tomohiro; Yamaguchi, Ryo; Takahashi, Kyusuke; Sakamoto, Yuichi

    2014-01-01

    The effect of high-voltage electrical stimulation on fruit body formation in cultivating mushrooms was evaluated using a compact pulsed power generator designed and based on an inductive energy storage system. An output voltage from 50 to 130 kV with a 100 ns pulse width was used as the electrical stimulation to determine the optimum amplitude. The pulsed high voltage was applied to a sawdust-based substrate of Lyophyllum decastes and natural logs hosting Lentinula edodes, Pholiota nameko, and Naematoloma sublateritium. The experimental results showed that the fruit body formation of mushrooms increased 1.3–2.0 times in terms of the total weight. The accumulated yield of Lentinula edodes for four cultivation seasons was improved from 160 to 320 g by applying voltages of 50 or 100 kV. However, the yield was decreased from 320 to 240 g upon increasing the applied voltage from 100 to 130 kV. The yield of the other types of mushrooms showed tendencies similar to those of Lentinula edodes when voltage was applied. An optimal voltage was confirmed for efficient fruit body induction. The hypha activity was evaluated by the amount of hydrophobin release, which was mainly observed before the fruit body formation. The hydrophobin release decreased for three hours after stimulation. However, the hydrophobin release from the vegetative hyphae increased 2.3 times one day after the stimulation.

  19. Q-switched laser in an SMS cavity for inhibiting nonlinear effects.

    PubMed

    Zhou, Jiaqi; Lu, Yi; He, Bing; Gu, Xijia

    2015-07-01

    In the design of high-power Q-switched fiber lasers, nonlinear effects often become barriers that prevent the scale up of pulse energy and peak power. New designs and components that could inhibit or suppress nonlinear effects are in high demand, particularly in all-fiber configurations. In this paper, we demonstrated a Q-switched Yb-doped fiber laser in a single-mode multimode single-mode (SMS) structure to inhibit fiber nonlinear effects. The laser-generated Q-switched pulses with a peak power close to 1 kW (pulse width and energy of 100 ns and 92 μJ, respectively). The output spectrum of this laser was compared with that of a Q-switched Yb-doped fiber laser built in a conventional configuration with similar output peak power. The results showed, for the first time to our knowledge, that the SMS Q-switched laser completely inhibited the stimulated Raman scattering and significantly reduced self-phase modulation. PMID:26193155

  20. Reaction cycle and thermodynamics in bacteriorhodopsin

    NASA Technical Reports Server (NTRS)

    Lanyi, J. K.

    1992-01-01

    Light causes the all-trans to 13-cis isomerization of the retinal in bacteriorhodopsin; the thermal relaxation leading back to the initial state drives proton transport first via proton transfer between the retinal Schiff base and D85 and then between the Schiff base and D96. The reaction sequence and thermodynamics of this photocycle are described by measuring time-resolved absorption changes with a gated multichannel analyzer between 100 ns and 100 ms, at six temperatures between 5 degrees C and 30 degrees C. Analysis of the energetics of the chromophore reaction sequence is on the basis of a recently proposed model (Varo & Lanyi, Biochemistry 30, 5016-5022, 1991) which consists of a single cycle and many reversible reactions: BR -hv-->K<==>L<==>M1-->M2<==>N<==>O-->BR. The existence of the M1-->M2 reaction, which functions as the switch in the proton transfer, is confirmed by spectroscopic evidence. The calculated thermodynamic parameters indicate that the exchange of free energy between the protein and the protons is at the switch step. Further, a large entropy decrease at this reaction suggests a protein conformation change which will conserve delta G for driving the completion of the reaction cycle. The results provide insights to mechanism and energy coupling in this system, with possible relevance to the general question of how ion pumps function.

  1. Polymer-ionic liquid ternary systems for Li-battery electrolytes: Molecular dynamics studies of LiTFSI in a EMIm-TFSI and PEO blend

    SciTech Connect

    Costa, Luciano T.

    2015-07-14

    This paper presents atomistic molecular dynamics simulation studies of lithium bis(trifluoromethane)sulfonylimide (LiTFSI) in a blend of 1-ethyl-3-methylimidazolium (EMIm)-TFSI and poly(ethylene oxide) (PEO), which is a promising electrolyte material for Li- and Li-ion batteries. Simulations of 100 ns were performed for temperatures between 303 K and 423 K, for a Li:ether oxygen ratio of 1:16, and for PEO chains with 26 EO repeating units. Li{sup +} coordination and transportation were studied in the ternary electrolyte system, i.e., PEO{sub 16}LiTFSI⋅1.0 EMImTFSI, by applying three different force field models and are here compared to relevant simulation and experimental data. The force fields generated significantly different results, where a scaled charge model displayed the most reasonable comparisons with previous work and overall consistency. It is generally seen that the Li cations are primarily coordinated to polymer chains and less coupled to TFSI anion. The addition of EMImTFSI in the electrolyte system enhances Li diffusion, associated to the enhanced TFSI dynamics observed when increasing the overall TFSI anion concentration in the polymer matrix.

  2. ESSENSE: Ultra high resolution spectroscopy for the ESS

    NASA Astrophysics Data System (ADS)

    Pasini, Stefano; Monkenbusch, Michael; Kozielewski, Tadeusz

    2016-09-01

    The instrument concept for a very high intensity neutron spin-echo spectrometer with ultimate resolution properties has been developed and submitted as an instrument proposal to ESS. Effective intensity gain factors up to 30 compared to the best current instruments are anticipated. In addition the resolution will be boosted to the technical limits by newly designed superconducting precession solenoids. The intensity gain results from the use of an optimized guide transporting the high flux from the ESS cold moderator on the one side and from the utilization of an extended wavelength frame of 8 Å yielding a multiplication of information collection rate on the other side. The instrument thus enables novel views on soft matter systems ranging from polymers, functional gels and more to to dynamics of biological molecules with relevance for MD development; the employment of new techniques for surface NSE (GINSE) may contribute to new knowledge in tribology and lubrication and other surface phenomena that currently are hampered by low intensity. New developments in “intelligent” polymers as e.g. self-healing, the properties of which depend on molecular mobility and dynamics, require observation at many 100 ns of correlation times with high intensity, which can be made with ESSENSE.

  3. Injury thresholds for topical-cream-coated skin of hairless guinea pigs (cavia porcellus) in the near-infrared region

    NASA Astrophysics Data System (ADS)

    Pocock, Ginger M.; Zohner, Justin J.; Stolarski, David J.; Buchanan, Kelvin C.; Jindra, Nichole M.; Figueroa, Manuel A.; Chavey, Lucas J.; Imholte, Michelle L.; Thomas, Robert J.; Rockwell, Benjamin A.

    2006-02-01

    The reflectance and absorption of the skin plays a vital role in determining how much radiation will be absorbed by human tissue. Any substance covering the skin would change the way radiation is reflected and absorbed and thus the extent of thermal injury. Hairless guinea pigs (cavia porcellus) in vivo were used to evaluate how the minimum visible lesion threshold for single-pulse laser exposure is changed with a topical agent applied to the skin. The ED 50 for visible lesions due to an Er: glass laser at 1540-nm with a pulse width of 50-ns was determined, and the results were compared with model predictions using a skin thermal model. The ED50 is compared with the damage threshold of skin coated with a highly absorbing topical cream at 1540 nm to determine its effect on damage pathology and threshold. The ED 50 for the guinea pig was then compared to similar studies using Yucatan minipigs and Yorkshire pigs at 1540-nm and nanosecond pulse duration. 1,2 The damage threshold at 24-hours of a Yorkshire pig for a 2.5-3.5-mm diameter beam for 100 ns was 3.2 Jcm -2; very similar to our ED 50 of 3.00 Jcm -2 for the hairless guinea pigs.

  4. Transient suppression of gap junctional intercellular communication after exposure to 100-nanosecond pulsed electric fields.

    PubMed

    Steuer, Anna; Schmidt, Anke; Labohá, Petra; Babica, Pavel; Kolb, Juergen F

    2016-12-01

    Gap junctional intercellular communication (GJIC) is an important mechanism that is involved and affected in many diseases and injuries. So far, the effect of nanosecond pulsed electric fields (nsPEFs) on the communication between cells was not investigated. An in vitro approach is presented with rat liver epithelial WB-F344 cells grown and exposed in a monolayer. In order to observe sub-lethal effects, cells were exposed to pulsed electric fields with a duration of 100ns and amplitudes between 10 and 20kV/cm. GJIC strongly decreased within 15min after treatment but recovered within 24h. Gene expression of Cx43 was significantly decreased and associated with a reduced total amount of Cx43 protein. In addition, MAP kinases p38 and Erk1/2, involved in Cx43 phosphorylation, were activated and Cx43 became hyperphosphorylated. Immunofluorescent staining of Cx43 displayed the disassembly of gap junctions. Further, a reorganization of the actin cytoskeleton was observed whereas tight junction protein ZO-1 was not significantly affected. All effects were field- and time-dependent and most pronounced within 30 to 60min after treatment. A better understanding of a possible manipulation of GJIC by nsPEFs might eventually offer a possibility to develop and improve treatments. PMID:27439151

  5. Effects of high voltage nanosecond electric pulses on eukaryotic cells (in vitro): A systematic review.

    PubMed

    Batista Napotnik, Tina; Reberšek, Matej; Vernier, P Thomas; Mali, Barbara; Miklavčič, Damijan

    2016-08-01

    For this systematic review, 203 published reports on effects of electroporation using nanosecond high-voltage electric pulses (nsEP) on eukaryotic cells (human, animal, plant) in vitro were analyzed. A field synopsis summarizes current published data in the field with respect to publication year, cell types, exposure configuration, and pulse duration. Published data were analyzed for effects observed in eight main target areas (plasma membrane, intracellular, apoptosis, calcium level and distribution, survival, nucleus, mitochondria, stress) and an additional 107 detailed outcomes. We statistically analyzed effects of nsEP with respect to three pulse duration groups: A: 1-10ns, B: 11-100ns and C: 101-999ns. The analysis confirmed that the plasma membrane is more affected with longer pulses than with short pulses, seen best in uptake of dye molecules after applying single pulses. Additionally, we have reviewed measurements of nsEP and evaluations of the electric fields to which cells were exposed in these reports, and we provide recommendations for assessing nanosecond pulsed electric field effects in electroporation studies. PMID:26946156

  6. Ionization cross sections of small cationic carbon clusters in high-energy collisions with helium atoms and stability of multiply charged species

    SciTech Connect

    Mezdari, F.; Wohrer-Beroff, K.; Chabot, M.; Martinet, G.; Della Negra, S.; Desesquelles, P.; Hamrita, H.; LePadellec, A.

    2005-09-15

    Single, double, triple, and quadruple ionization cross sections of small cationic carbon clusters C{sub n}{sup +} colliding with helium atoms at a fixed velocity (2.6 atomic units) have been measured. The size ranges from n=1 to n=10 for single to triple ionization, from n=5 to n=10 for the quadruple ionization. The dependence of the cross sections with the cluster size is found to be well reproduced by predictions of the independent atom and electron (IAE) collision model. This extends the applicability of this simple model to higher n values and to a higher ionization degree than previously done [M. Chabot et al., Eur. Phys. J. D 14, 5 (2001)]. The branching ratios of multiply charged C{sub n}{sup q+} clusters remaining intact over a 100 ns time window have been measured (n=3-10, q=2-3). Branching ratios of nonfragmented doubly charged clusters have been interpreted on the basis of calculated internal energies of C{sub n}{sup 2+} due to single ionization of C{sub n}{sup +} clusters using the IAE model. This allowed estimates of the minimum energies required to fragment these C{sub n}{sup 2+} species to be derived.

  7. Ionization cross sections of small cationic carbon clusters in high-energy collisions with helium atoms and stability of multiply charged species

    NASA Astrophysics Data System (ADS)

    Mezdari, F.; Wohrer-Béroff, K.; Chabot, M.; Martinet, G.; Della Negrâ, S.; Désesquelles, P.; Hamrita, H.; Lepadellec, A.

    2005-09-01

    Single, double, triple, and quadruple ionization cross sections of small cationic carbon clusters Cn+ colliding with helium atoms at a fixed velocity (2.6 atomic units) have been measured. The size ranges from n=1 to n=10 for single to triple ionization, from n=5 to n=10 for the quadruple ionization. The dependence of the cross sections with the cluster size is found to be well reproduced by predictions of the independent atom and electron (IAE) collision model. This extends the applicability of this simple model to higher n values and to a higher ionization degree than previously done [M. Chabot , Eur. Phys. J. D 14, 5 (2001)]. The branching ratios of multiply charged Cnq+ clusters remaining intact over a 100ns time window have been measured ( n=3-10 , q=2-3 ). Branching ratios of nonfragmented doubly charged clusters have been interpreted on the basis of calculated internal energies of Cn2+ due to single ionization of Cn+ clusters using the IAE model. This allowed estimates of the minimum energies required to fragment these Cn2+ species to be derived.

  8. Inactivation of spores using pulsed electric field in a pressurized flow system

    SciTech Connect

    Choi, Jaegu; Wang Douyan; Namihira, Takao; Katsuki, Sunao; Akiyama, Hidenori; Lin Xiaofei; Sato, Hiroshi; Seta, Harumichi; Matsubara, Hitoshi; Saeki, Takeshi

    2008-11-01

    Pulsed electric field (PEF) inactivation is a very effective method to kill bacteria in liquid while avoiding thermal damage. However, only a limited inactivation effect on spores has been reported to date and the possible mechanisms are still unclear. Therefore, a study of inactivation of spores using PEF in a pressurized flow system is reported in this paper. PEF with a maximum magnitude higher than 110 kV/cm and a pulse width of 100 ns has been applied to a carefully designed treatment chamber through which a suspension fluid of 0.5 MPa continuously flows. Using the proposed PEF inactivation method, maximum 6.7 log reductions were achieved for B. subtilis spores that were investigated. These reductions were much greater than those obtained by a heat inactivation approach. Through frequency analysis using the frequency components of the applied pulses and the frequency response of the equivalent circuit of the spore, it was found that most voltage is applied to the outside of the core in the lower frequency and to the inside in the upper frequency. Also, transmission electron microscope micrographs of B. subtilis spores were taken in order to verify the effect of the PEF treatment.

  9. Diagnosis of high-intensity pulsed heavy ion beam generated by a novel magnetically insulated diode with gas puff plasma gun.

    PubMed

    Ito, H; Miyake, H; Masugata, K

    2008-10-01

    Intense pulsed heavy ion beam is expected to be applied to materials processing including surface modification and ion implantation. For those applications, it is very important to generate high-purity ion beams with various ion species. For this purpose, we have developed a new type of a magnetically insulated ion diode with an active ion source of a gas puff plasma gun. When the ion diode was operated at a diode voltage of about 190 kV, a diode current of about 15 kA, and a pulse duration of about 100 ns, the ion beam with an ion current density of 54 A/cm(2) was obtained at 50 mm downstream from the anode. By evaluating the ion species and the energy spectrum of the ion beam via a Thomson parabola spectrometer, it was confirmed that the ion beam consists of nitrogen ions (N(+) and N(2+)) of energy of 100-400 keV and the proton impurities of energy of 90-200 keV. The purity of the beam was evaluated to be 94%. The high-purity pulsed nitrogen ion beam was successfully obtained by the developed ion diode system.

  10. A millisecond pulsar timing array

    NASA Astrophysics Data System (ADS)

    Hobbs, George; Manchester, Dick; Sarkissian, John; Bailes, Matthew; Bhat, Ramesh; Jenet, Rick; van Straten, Willem; Yardley, Daniel Roger Billing; Burke, Sarah; Oslowski, Stefan; Hotan, Aidan; Champion, David

    2010-10-01

    The Parkes Pulsar Timing Array (PPTA) project has three primary goals: (a) detection of gravitational waves from astronomical sources, (b) establishment of a pulsar timescale, and (c) improvement of our understanding of Solar-system dynamics. There are many secondary goals, some astrophysical and some instrumental/technique oriented. Achievement of these ambitious primary goals requires frequent observations of at least 20 MSPs at two or preferably three widely spaced frequencies over several years. We wish to continue observing the PPTA sample at intervals of 2-3 weeks using both the 10/50cm and Multibeam receivers. The digital filterbanks (PDFB3, PDFB4) and the baseband system (APSR) are used for data recording. With the new instruments and development of an efficient pipeline processing system, we have achieved the world's best pulsar timing precision, with four pulsars having rms residuals of less than or about 100 ns and 13 less than 1 microsecond. We are collaborating with the European and North American pulsar timing array groups (EPTA and NANOGrav, respectively) to obtain more frequent observations and a larger pulsar sample. Because of the high sensitivity and wide bandwidths required, RFI mitigation is an important part of the project.

  11. A millisecond pulsar timing array

    NASA Astrophysics Data System (ADS)

    Manchester, Dick; Sarkissian, John; Hobbs, George; Bailes, Matthew; Bhat, Ramesh; Jenet, Rick; van Straten, Willem; Yardley, Daniel Roger Billing; Champion, David; Burke, Sarah; Oslowski, Stefan; Hotan, Aidan

    2009-10-01

    The Parkes Pulsar Timing Array (PPTA) project has three primary goals: (a) detection of gravitational waves from astronomical sources, (b) establishment of a pulsar timescale, and (c) improvement of our understanding of Solar-system dynamics. There are many secondary goals, some astrophysical and some instrumental/technique oriented. Achievement of these ambitious primary goals requires frequent observations of at least 20 MSPs at two or preferably three widely spaced frequencies over several years. We wish to continue observing the PPTA sample at intervals of 2-3 weeks using both the 10/50cm and Multibeam receivers. The digital filterbanks (PDFB3, PDFB4) and the baseband systems (CPSR2; APSR) are used for data recording. With the new instruments and development of an efficient pipeline processing system, we have achieved the world's best pulsar timing precision, with three pulsars having rms residuals of less than or about 100 ns and more than half less than 1 microsecond. We are collaborating with the European and North American pulsar timing array groups (EPTA and NANOGrav, respectively) to obtain more frequent observations and a larger pulsar sample. Because of the high sensitivity and wide bandwidths required, RFI mitigation is an important part of the project.

  12. A millisecond pulsar timing array

    NASA Astrophysics Data System (ADS)

    Manchester, Dick; Sarkissian, John; Hobbs, George; Bailes, Matthew; Bhat, Ramesh; Hotan, Aidan; Jenet, Rick; van Straten, Willem; Yardley, Daniel Roger Billing; Champion, David; You, Xiaopeng; Burke, Sarah

    2009-04-01

    The Parkes Pulsar Timing Array (PPTA) project has three primary goals: (a) detection of gravitational waves from astronomical sources, (b) establishment of a pulsar timescale, and (c) improvement of our understanding of Solar-system dynamics. There are many secondary goals, some astrophysical and some instrumental/technique oriented. Achievement of these ambitious primary goals requires frequent observations of at least 20 MSPs at two or preferably three widely spaced frequencies over several years. We wish to continue observing the PPTA sample at intervals of 2-3 weeks using both the 10/50cm and Multibeam receivers. The digital filterbanks (PDFB3, PDFB4) and the baseband systems (CPSR2; APSR) are used for data recording. With the new instruments and development of an efficient pipeline processing system, we have achieved the world's best pulsar timing precision, with three pulsars having rms residuals of less than or about 100 ns and more than half less than 1 microsecond. We are collaborating with the European and North American pulsar timing array groups (EPTA and NANOGrav, respectively) to obtain more frequent observations and a larger pulsar sample. Because of the high sensitivity and wide bandwidths required, RFI mitigation is an important part of the project.

  13. A millisecond pulsar timing array

    NASA Astrophysics Data System (ADS)

    Manchester, Dick; Sarkissian, John; Hobbs, George; Bailes, Matthew; Bhat, Ramesh; Jenet, Rick; van Straten, Willem; Yardley, Daniel Roger Billing; Burke, Sarah; Oslowski, Stefan; Hotan, Aidan; Champion, David

    2010-04-01

    The Parkes Pulsar Timing Array (PPTA) project has three primary goals: (a) detection of gravitational waves from astronomical sources, (b) establishment of a pulsar timescale, and (c) improvement of our understanding of Solar-system dynamics. There are many secondary goals, some astrophysical and some instrumental/technique oriented. Achievement of these ambitious primary goals requires frequent observations of at least 20 MSPs at two or preferably three widely spaced frequencies over several years. We wish to continue observing the PPTA sample at intervals of 2-3 weeks using both the 10/50cm and Multibeam receivers. The digital filterbanks (PDFB3, PDFB4) and the baseband systems (CPSR2; APSR) are used for data recording. With the new instruments and development of an efficient pipeline processing system, we have achieved the world's best pulsar timing precision, with four pulsars having rms residuals of less than or about 100 ns and 13 less than 1 microsecond. We are collaborating with the European and North American pulsar timing array groups (EPTA and NANOGrav, respectively) to obtain more frequent observations and a larger pulsar sample. Because of the high sensitivity and wide bandwidths required, RFI mitigation is an important part of the project.

  14. Selective preparation of hard dental tissue: classical and laser treatments comparison

    NASA Astrophysics Data System (ADS)

    Dostálova, Tat'jana; Jelínkova, Helena; Němec, Michal; Koranda, Petr; Miyagi, Mitsunobu; Iwai, Katsumasa; Shi, Yi-Wei; Matsuura, Yuji

    2006-02-01

    For the purpose of micro-selective preparation which is part of the modern dentistry four various methods were examined: ablation by Er:YAG laser radiation (free-running or Q-switching regime), preparation of tissues by ultrasonic round ball tip, and by the classical dental drilling machine using diamond round bur. In the case of Er:YAG laser application the interaction energy 40 mJ in pulse of 200 us yielding to the interaction intensity 62 kW/cm2, and 20 mJ in pulse of 100 ns yielding to the interaction intensity 62 MW/cm2 was used for the case of free running, and Q-switch regime, respectively. For comparisson with the classical methods the ultrasound preparation tip (Sonixflex cariex TC, D - Sonicsys micro) and dental driller together with usual preparation burrs and standard handpiece were used. For the interaction experiment the samples of extracted human teeth and ebony cut into longitudinal sections and polished were used. The thickness of the prepared samples ranged from 5 to 7 mm. The methods were compared from the point of prepared cavity shape (SEM), inner surface, and possibility of selective removal of carries. The composite filling material was used to reconstruct the cavities. The dye penetrating analysis was performed.

  15. Distribution and dynamics of quinones in the lipid bilayer mimicking the inner membrane of mitochondria.

    PubMed

    Kaurola, Petri; Sharma, Vivek; Vonk, Amanda; Vattulainen, Ilpo; Róg, Tomasz

    2016-09-01

    Quinone and its analogues (Q) constitute an important class of compounds that perform key electron transfer reactions in oxidative- and photo-phosphorylation. In the inner membrane of mitochondria, ubiquinone molecules undergo continuous redox transitions enabling electron transfer between the respiratory complexes. In such a dynamic system undergoing continuous turnover for ATP synthesis, an uninterrupted supply of substrate molecules is absolutely necessary. In the current work, we have performed atomistic molecular dynamics simulations and free energy calculations to assess the structure, dynamics, and localization of quinone and its analogues in a lipid bilayer, whose composition mimics the one in the inner mitochondrial membrane. The results show that there is a strong tendency of both quinone and quinol molecules to localize in the vicinity of the lipids' acyl groups, right under the lipid head group region. Additionally, we observe a second location in the middle of the bilayer where quinone molecules tend to stabilize. Translocation of quinone through a lipid bilayer is very fast and occurs in 10-100ns time scale, whereas the translocation of quinol is at least an order of magnitude slower. We suggest that this has important mechanistic implications given that the localization of Q ensures maximal occupancy of the Q-binding sites or Q-entry points in electron transport chain complexes, thereby maintaining an optimal turnover rate for ATP synthesis. PMID:27342376

  16. Experimental and computational study of the liquid-solid transition in tin.

    SciTech Connect

    Foiles, Stephen Martin; Davis, Jean-Paul

    2005-10-01

    An experimental technique was developed to perform isentropic compression of heated liquid tin samples at the Z Accelerator, and multiple such experiments were performed to investigate solidification under rapid compression. Preliminary analyses, using two different methods, of data from experiments with high uncertainty in sample thickness suggest that solidification can begin to occur during isentropic compression on time scales of less than 100 ns. Repeatability of this result has not been confirmed due to technical issues on the subsequent experiments performed. First-principles molecular-dynamics calculations based on density-functional theory showed good agreement with experimentally-determined structure factors for liquid tin, and were used to investigate the equation of state and develop a novel interatomic pseudo-potential for liquid tin and its high-pressure solid phase. Empirical-potential molecular-dynamics calculations, using the new potential, gave results for the solid-liquid interface velocity, which was found to vary linearly with difference in free energy between the solid and liquid phases, as well as the liquidus, the maximum over-pressurization, and the solid-liquid interfacial energy. These data will prove useful in future modeling of solidification kinetics for liquid tin.

  17. Magnetic field measurements for study of fast electron transport in magnetized HED plasma

    NASA Astrophysics Data System (ADS)

    Sawada, Hiroshi; Griffin, Brandon; Presura, Radu; Haque, Showera; Sentoku, Yasuhiko

    2014-10-01

    Interaction of megagauss magnetic fields with high energy density (HED) plasma is of great interest in the field of magnetized plasma. The field changes fundamental properties of the HED plasma such as thermal and magnetic diffusion. A coupled capability utilizing the 1.0 MA Zebra pulsed power generator and the 50 TW Leopard laser at Nevada Terawatt Facility enables to create such a condition for studies of magnetized plasma properties. We have conducted an experiment to measure magnetic fields generated by a 1.0 MA, 100 ns Zebra pulsed current in stainless steel coils. Using a 532 nm continuous laser from a single longitudinal mode laser system, the temporal change in the magnetic field was measured with the Faraday rotation in F2 glass. The probe laser passing through the 1.5 mm in radius and 1.75 mm thick glass placed in the vicinity of the inductive coils was split with a Glan-Taylor prism to measure vertical and horizontal polarization components with photodiodes. We will present the analysis of the experimental result and a design of a coupled experiment for study of fast electron transport in the magnetized plasma.

  18. Hard X-ray and Particle Beams Research on 1.7 MA Z-pinch and Laser Plasma Experiments

    NASA Astrophysics Data System (ADS)

    Shrestha, Ishor; Kantsyrev, Victor; Safronova, Alla; Esaulov, Andrey; Nishio, Mineyuki; Shlyaptseva, Veronica; Keim, Steven; Weller, Michael; Stafford, Austin; Petkov, Emil; Schultz, Kimberly; Cooper, Matthew; PPDL Team

    2013-10-01

    Studies of hard x-ray (HXR) emission, electron and ion beam generation in z-pinch and laser plasmas are important for Inertial Confinement Fusion (ICF) and development of HXR sources from K-shell and L-shell radiation. The characteristics of HXR and particle beams produced by implosions of planar wire arrays, nested and single cylindrical wire arrays, and X-pinches were analyzed on 100 ns UNR Zebra generator with current up to 1.7 MA. In addition, the comparison of characteristics of HXR and electron beams on Zebra and 350 fs UNR Leopard laser experiments with foils has been performed. The diagnostics include Faraday cups, HXR diodes, different x-ray spectrometers and imaging systems, and ion mass spectrometer using the technique of Thomson parabola. Future work on HXRs and particle beams in HED plasmas is discussed. This work was supported by the DOE/NNSA Cooperative agreement DE-NA0001984 and in part by DE-FC52-06NA27616. This work was also supported by the Defense Threat Reduction Agency, Basic Research Award # HDTRA1-13-1-0033, to University of Nevada, Reno.

  19. Physiological monitoring of optically trapped cells: assessing the effects of confinement by 1064-nm laser tweezers using microfluorometry.

    PubMed Central

    Liu, Y; Sonek, G J; Berns, M W; Tromberg, B J

    1996-01-01

    We report the results of microfluorometric measurements of physiological changes in optically trapped immotile Chinese hamster ovary cells (CHOs) and motile human sperm cells under continuous-wave (CW) and pulsed-mode trapping conditions at 1064 nm. The fluorescence spectra derived from the exogenous fluorescent probes laurdan, acridine orange, propidium iodide, and Snarf are used to assess the effects of optical confinement with respect to temperature, DNA structure, cell viability, and intracellular pH, respectively. In the latter three cases, fluorescence is excited via a two-photon process, using a CW laser trap as the fluorescence excitation source. An average temperature increase of < 0.1 +/- 0.30 degrees C/100 mW is measured for cells when held stationary with CW optical tweezers at powers of up to 400 mW. The same trapping conditions do not appear to alter DNA structure or cellular pH. In contrast, a pulsed 1064-nm laser trap (100-ns pulses at 40 microJ/pulse and average power of 40 mW) produced significant fluorescence spectral alterations in acridine orange, perhaps because of thermally induced DNA structural changes or laser-induced multiphoton processes. The techniques and results presented herein demonstrate the ability to perform in situ monitoring of cellular physiology during CW and pulsed laser trapping, and should prove useful in studying mechanisms by which optical tweezers and microbeams perturb metabolic function and cellular viability. PMID:8889192

  20. Structural elucidation of SrtA enzyme in Enterococcus faecalis: an emphasis on screening of potential inhibitors against the biofilm formation.

    PubMed

    Selvaraj, Chandrabose; Sivakamavalli, Jeyachandran; Vaseeharan, Baskaralingam; Singh, Poonam; Singh, Sanjeev Kumar

    2014-07-01

    Enterococcus faecalis is a pathogenic Gram-positive bacterium, which mainly infects humans through urinary tract infections. SrtA is an essential enzyme for survival of E. faecalis, and inhibition of this particular enzyme will reduce the virulence of biofilm formation. It is proved to be associated with the microbial surface protein embedded signal transduction mechanism and promising as a suitable anti-microbial drug target for E. faecalis. The present work gives an inclusive description of SrtA isolated from E. faecalis through computational and experimental methodologies. For exploring the mechanism of SrtA and to screen potential leads against E. faecalis, we have generated three-dimensional models through homology modeling. The 3D model showed conformational stability over time, confirming the quality of the starting 3D model. Large scale 100 ns molecular dynamics simulations show the intramolecular changes occurring in SrtA, and multiple conformations of structure based screening elucidate potential leads against this pathogen. Experimental results showed that the screened compounds are active showing anti-microbial and anti-biofilm activity, as SrtA is known to play an important role in E. faecalis biofilm formation. Experimental results also suggest that SrtA specific screened compounds have better anti-biofilm activity than the available inhibitors. Therefore, we believe that development of these compounds would be an impetus to design the novel chief SrtA inhibitors against E. faecalis.

  1. Generation of Nonlinear Force Driven Blocks from Skin Layer Interaction of Petawatt-Picosecond Laser Pulses for ICF

    NASA Astrophysics Data System (ADS)

    Heinrich, Hora; Cang, Yu; He, Xiantu; Zhang, Jie; F, Osman; J, Badziak; F, P. Boody; S, Gammino; R, Höpfl; K, Jungwirth; B, Kralikova; J, Kraska; L, Laska; Liu, Hong; G, H. Miley; P, Parys; Peng, Hansheng; M, Pfeifer; K, Rohlena; J, Skala; Z, Skladanowski; L, Torrisi; J, Ullschmied; J, Wolowski; Zhang, Weiyan

    2004-02-01

    The discovery of the essential difference of maximum ion energy for TW - ps laser plasma interaction compared with the 100 ns laser pulses [1] led to the theory of a skin layer model [2] where the control of prepulses suppressed the usual relativistic self-focusing. The subsequent generation of two nonlinear force driven blocks has been demonstrated experimentally and in extensive numerical studies where one block moves against the laser light and the other block into the irradiated target. These blocks of nearly solid state density DT plasma correspond to ion beam current densities [3] exceeding 1010 A/cm2 where the ion velocity can be chosen up to highly relativistic values. Using the results of the expected ignition of DT fuel by light ion beams, a self-sustained fusion reaction front may be generated even into uncompressed solid DT fuel similar to the Nuckolls-Wood [4] scheme where 10 kJ laser pulses produce 100 MJ fusion energy. This new and simplified scheme of laser-ICF needs and optimisation of the involved parameters.

  2. Equilibrated Atomic Models of Outward-Facing P-glycoprotein and Effect of ATP Binding on Structural Dynamics

    PubMed Central

    Pan, Lurong; Aller, Stephen G.

    2015-01-01

    P-glycoprotein (Pgp) is an ATP-binding cassette (ABC) transporter that alternates between inward- and outward-facing conformations to capture and force substrates out of cells like a peristaltic pump. The high degree of similarity in outward-facing structures across evolution of ABC transporters allowed construction of a high-confidence outward-facing Pgp atomic model based on crystal structures of outward-facing Sav1866 and inward-facing Pgp. The model adhered to previous experimentally determined secondary- and tertiary- configurations during all-atom molecular dynamics simulations in the presence or absence of MgATP. Three long lasting (>100 ns) meta-stable states were apparent in the presence of MgATP revealing new insights into alternating access. The two ATP-binding pockets are highly asymmetric resulting in differential control of overall structural dynamics and allosteric regulation of the drug-binding pocket. Equilibrated Pgp has a considerably different electrostatic profile compared to Sav1866 that implicates significant kinetic and thermodynamic differences in transport mechanisms. PMID:25600711

  3. Photoluminescence of P3HT nanoparticles

    NASA Astrophysics Data System (ADS)

    Dujovne, Irene; Labastide, Joelle; Baghgar, Mina; McKenna, Aidan; Barnes, Austin M.; Venkataraman, D.; Barnes, Michael D.

    2012-02-01

    Polythiophenes are semiconducting polymers that have been designed to crystallize. The photophysics of semicrystalline polythiophene and polythiophene-blends are the focus of intense research efforts across different disciplines. In these systems there is a competition between charge separation and recombination. Exciton diffusion length in organic-semiconductors is a major road-block for efficient solar energy harvesting devices since, for direct bandgap organic materials, this distance is about 10 nanometers. Thus, efficient extraction of photogenerated electrons and holes requires engineering polymer domain dimensions in this size range. In our initial investigations of the photophysics of isolated P3HT nanoparticles (15 - 130 nm), we have observed several intriguing size-dependent features in the single-particle photoluminescence (PL) connected with exciton diffusion and dissociation dynamics. In addition to the short-time behavior, we also observe size-dependent differences in PL decay at long times. In the 10 - 100 ns time regime, the PL originates not from radiative transitions of bound excitons, but rather from charge-separation followed by bi-polaron recombination--and thus provides an interesting measure of exciton fission probability within the nanoparticle.

  4. Preliminary Results of a 10 kJ Z-Pinch

    SciTech Connect

    Cortazar, O. D.; Piriz, A. R.; Prieto, G. Rodriguez; Hoffmann, D. H. H.; Tahir, N. A.

    2008-04-07

    Preliminary results obtained on 10 kJ Z-pinch device developed at the Plasma and Electrical Discharge Laboratory in the University of Castilla-La Mancha are presented. The device called ENERGU-1 is composed by 8 capacitors (0.5 {mu}F, 75 kV, 20 nH) connected in parallel to a discharge chamber by means of one high power plane transmission line by mean of 8 spark-gaps switches triggered by a 100 kV, 13 ns trigger pulse. The discharge chamber is a cylindrical Pyrex glass tube externally surrounded by a SF{sub 6} isolation atmosphere with the electrodes at the ends. Two different chambers have been studied by discharging the capacitor bank energy in deuterium for optimizing the D-D nuclear fusion reactions: one of 100 mm long by 100 mm inner diameter and the other of the same length and 70 mm inner diameter. Several sequences of ultrahigh speed converter camera photography (5 ns) are presented showing the implosion of plasma columns for different deuterium pressure and currents. Preliminary measurements of integrated 2.45 MeV neutron emissions by a silver activated neutron counter are analyzed as a function of electrical and constructive parameters. A yield of 10{sup 7}-10{sup 8} D-D fusion reactions by shot is reported when the optimum conditions are reached conducting currents of 400-600 kA with a plasma column lifetime above 100 ns.

  5. Molecular dynamics study of naturally existing cavity couplings in proteins.

    PubMed

    Barbany, Montserrat; Meyer, Tim; Hospital, Adam; Faustino, Ignacio; D'Abramo, Marco; Morata, Jordi; Orozco, Modesto; de la Cruz, Xavier

    2015-01-01

    Couplings between protein sub-structures are a common property of protein dynamics. Some of these couplings are especially interesting since they relate to function and its regulation. In this article we have studied the case of cavity couplings because cavities can host functional sites, allosteric sites, and are the locus of interactions with the cell milieu. We have divided this problem into two parts. In the first part, we have explored the presence of cavity couplings in the natural dynamics of 75 proteins, using 20 ns molecular dynamics simulations. For each of these proteins, we have obtained two trajectories around their native state. After applying a stringent filtering procedure, we found significant cavity correlations in 60% of the proteins. We analyze and discuss the structure origins of these correlations, including neighbourhood, cavity distance, etc. In the second part of our study, we have used longer simulations (≥100 ns) from the MoDEL project, to obtain a broader view of cavity couplings, particularly about their dependence on time. Using moving window computations we explored the fluctuations of cavity couplings along time, finding that these couplings could fluctuate substantially during the trajectory, reaching in several cases correlations above 0.25/0.5. In summary, we describe the structural origin and the variations with time of cavity couplings. We complete our work with a brief discussion of the biological implications of these results.

  6. MAPPING THE GALACTIC CENTER WITH GRAVITATIONAL WAVE MEASUREMENTS USING PULSAR TIMING

    SciTech Connect

    Kocsis, Bence; Ray, Alak; Portegies Zwart, Simon E-mail: akr@tifr.res.in

    2012-06-10

    We examine the nHz gravitational wave (GW) foreground of stars and black holes (BHs) orbiting SgrA* in the Galactic center. A cusp of stars and BHs generates a continuous GW spectrum below 40 nHz; individual BHs within 1 mpc to SgrA* stick out in the spectrum at higher GW frequencies. The GWs and gravitational near-field effects can be resolved by timing pulsars within a few pc of this region. Observations with the Square Kilometer Array may be especially sensitive to intermediate-mass BHs in this region, if present. A 100 ns-10 {mu}s timing accuracy is sufficient to detect BHs of mass 1000 M{sub Sun} with pulsars at distance 0.1-1 pc in a 3 yr observation baseline. Unlike electromagnetic imaging techniques, the prospects for resolving individual objects through GW measurements improve closer to SgrA*, even if the number density of objects steeply increases inward. Scattering by the interstellar medium will pose the biggest challenge for such observations.

  7. An 8-GW long-pulse generator based on Tesla transformer and pulse forming network

    NASA Astrophysics Data System (ADS)

    Su, Jiancang; Zhang, Xibo; Li, Rui; Zhao, Liang; Sun, Xu; Wang, Limin; Zeng, Bo; Cheng, Jie; Wang, Ying; Peng, Jianchang; Song, Xiaoxin

    2014-06-01

    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.

  8. Detecting excess ionizing radiation by electromagnetic breakdown of air

    SciTech Connect

    Granatstein, Victor L.; Nusinovich, Gregory S.

    2010-09-15

    A scheme is proposed for detecting a concealed source of ionizing radiation by observing the occurrence of breakdown in atmospheric air by an electromagnetic wave whose electric field surpasses the breakdown field in a limited volume. The volume is chosen to be smaller than the reciprocal of the naturally occurring concentration of free electrons. The pulse duration of the electromagnetic wave must exceed the avalanche breakdown time (10-200 ns) and could profitably be as long as the statistical lag time in ambient air (typically, microseconds). Candidate pulsed electromagnetic sources over a wavelength range, 3 mm>{lambda}>10.6 {mu}m, are evaluated. Suitable candidate sources are found to be a 670 GHz gyrotron oscillator with 200 kW, 10 {mu}s output pulses and a Transversely Excited Atmospheric-Pressure (TEA) CO{sub 2} laser with 30 MW, 100 ns output pulses. A system based on 670 GHz gyrotron would have superior sensitivity. A system based on the TEA CO{sub 2} laser could have a longer range >100 m.

  9. Transform and relax sampling for highly anisotropic systems: Application to protein domain motion and folding

    NASA Astrophysics Data System (ADS)

    Kitao, Akio

    2011-07-01

    Transform and relax sampling (TRS) is proposed as a conformational sampling method to enhance "soft" fluctuation in highly anisotropic systems using molecular dynamics simulation. This method consists of three stages; transform, relax, and sampling. In the transform stage, molecular dynamics simulation is performed with randomly assigned force bias to enhance the fluctuations along relatively soft collective movements, as expected from the linear response theory. After relaxing the heated system to equilibrium without force bias in the relax stage, Monte Carlo-type determination is made as to whether the generated state is accepted or not. The sampling stage is then conducted for conformational sampling by conventional molecular dynamics simulation. TRS is first applied for the idealized multidimensional double-well Cα model to mimic protein open-close transition. Subsequently, it is applied to three different all-atom protein systems in an explicit solvent model; T4 lysozyme, glutamine binding protein, and a mini-protein chignolin. Investigation of structural variations in the hinge angle of T4 lysozyme in crystals is demonstrated by TRS. The liganded close structure of the glutamine binding protein is sampled starting from the unliganded open form. Chignolin is shown to fold into a native structure multiple times starting from highly extended structures within 100 ns. It is concluded that TRS sampled a reasonable conformational space within a relatively short simulation time in these cases. Possible future extensions of TRS are also discussed.

  10. Modeling nitrogen plasmas produced by intense electron beams

    NASA Astrophysics Data System (ADS)

    Angus, J. R.; Mosher, D.; Swanekamp, S. B.; Ottinger, P. F.; Schumer, J. W.; Hinshelwood, D. D.

    2016-05-01

    A new gas-chemistry model is presented to treat the breakdown of a nitrogen gas with pressures on the order of 1 Torr from intense electron beams with current densities on the order of 10 kA/cm2 and pulse durations on the order of 100 ns. For these parameter regimes, the gas transitions from a weakly ionized molecular state to a strongly ionized atomic state on the time scale of the beam pulse. The model is coupled to a 0D-circuit model using the rigid-beam approximation that can be driven by specifying the time and spatial profiles of the beam pulse. Simulation results are in good agreement with experimental measurements of the line-integrated electron density from experiments done using the Gamble II generator at the Naval Research Laboratory. It is found that the species are mostly in the ground and metastable states during the atomic phase, but that ionization proceeds predominantly through thermal ionization of optically allowed states with excitation energies close to the ionization limit.

  11. Time-resolved photoluminescence from self-assembled Ge(Si) islands in multilayer SiGe/Si and SiGe/SOI structures

    SciTech Connect

    Yablonskiy, A. N. Baidakova, N. A.; Novikov, A. V.; Lobanov, D. N.

    2013-11-15

    The results of a study of the spectral and temporal characteristics of the photoluminescence (PL) from multilayer structures with self-assembled Ge(Si) islands grown on silicon and 'silicon-on-insulator' substrates in relation to temperature and the excitation-light wavelength are presented. A substantial increase in island-related PL intensity is observed for structures with Ge(Si) islands grown on silicon substrates upon an increase in temperature from 4 to 70 K. This increase is due to the diffusion of nonequilibrium carriers from the silicon substrate into the active layer with the islands. In this case, a slow component with a characteristic time of {approx}100 ns appears in the PL rise kinetics. At the same time, no slow component in the PL rise kinetics and no rise in the PL intensity with increasing temperature are observed for structures grown on 'silicon-on-insulator' substrates, in which the active layer with the islands is insulated from the silicon substrate. It is found that absorption of the excitation light in the islands and SiGe wetting layers mainly contributes to the excitation of the PL signal from the islands under sub-bandgap optical pump conditions.

  12. RISE/FALL TIME ENHANCEMENT OF THE SPALLATION NEUTRON SOURCE LINAC LEBT CHOPPER SYSTEM

    SciTech Connect

    Peplov, Vladimir V; Saethre, Robert B

    2013-01-01

    The Spallation Neutron Source (SNS) Linac Low Energy Beam Transport (LEBT) chopper system provides fast chopping of the H- ion beam in the LEBT structure. Four identical pulsed power supplies (pulsers) create a series of 2.5 kV pulses to the four deflection electrodes floating on the focusing voltage of -50 kV. Each pulser is connected to the electrode through the network which consists of high voltage (HV) cables, a blocking capacitor, HV feed-through connectors, current-limiting resistors and transient voltage suppressors. Effective beam chopping requires minimal rise/fall time of the rectangular HV pulses on the load. In the present configuration these values are approximately 100 ns. Methods of reducing rise/fall time on the LEBT electrodes are discussed. Results of simulation and comparative measurements of the original and upgraded system on the test stand are presented. Furthermore, the effect of these changes on reliability degradation caused by arcing in the LEBT structure is discussed.

  13. Kinetics of liquid-mediated crystallization of amorphous Ge from multi-frame dynamic transmission electron microscopy

    SciTech Connect

    Santala, M. K.; Raoux, S.; Campbell, G. H.

    2015-12-24

    The kinetics of laser-induced, liquid-mediated crystallization of amorphous Ge thin films were studied using multi-frame dynamic transmission electron microscopy (DTEM), a nanosecond-scale photo-emission transmission electron microscopy technique. In these experiments, high temperature gradients are established in thin amorphous Ge films with a 12-ns laser pulse with a Gaussian spatial profile. The hottest region at the center of the laser spot crystallizes in ~100 ns and becomes nano-crystalline. Over the next several hundred nanoseconds crystallization continues radially outward from the nano-crystalline region forming elongated grains, some many microns long. The growth rate during the formation of these radial grains is measured with time-resolved imaging experiments. Crystal growth rates exceed 10 m/s, which are consistent with crystallization mediated by a very thin, undercooled transient liquid layer, rather than a purely solid-state transformation mechanism. The kinetics of this growth mode have been studied in detail under steady-state conditions, but here we provide a detailed study of liquid-mediated growth in high temperature gradients. Unexpectedly, the propagation rate of the crystallization front was observed to remain constant during this growth mode even when passing through large local temperature gradients, in stark contrast to other similar studies that suggested the growth rate changed dramatically. As a result, the high throughput of multi-frame DTEM provides gives a more complete picture of the role of temperature and temperature gradient on laser crystallization than previous DTEM experiments.

  14. Modeling the dynamics of one laser pulse surface nanofoaming of biopolymers

    NASA Astrophysics Data System (ADS)

    Lazare, S.; Bonneau, R.; Gaspard, S.; Oujja, M.; de Nalda, R.; Castillejo, M.; Sionkowska, A.

    2009-03-01

    Self standing films of biopolymers like gelatine, collagen, and chitosan irradiated with single nanosecond or femtosecond laser pulse easily yield on their surface, a nanofoam layer, formed by a cavitation and bubble growth mechanism. The laser foams have interesting properties that challenge the molecular features of the natural extracellular matrix and which make them good candidates for fabrication of artificial matrix (having nanoscopic fibers, large availability of cell adhesion sites, permeability to fluids due to the open cell structure). As part of the mechanistic study, the dynamics of the process has been measured in the nanosecond timescale by recording the optical transmission of the films at 632.8 nm during and after the foaming laser pulse. A rapid drop 100→0% taking place within the first 100 ns supports the cavitation mechanism as described by the previous negative pressure wave model. As modeled a strong pressure rise (˜several thousands of bar) first takes place in the absorption volume due to pressure confinement and finite sound velocity, and then upon relaxation after some delay equal to the pressure transit time gives rise to a rarefaction wave (negative pressure) in which nucleation and bubble growth are very fast.

  15. Energy Efficiency of Inductive Energy Storage System Pulsed Power Generator Using Fast Recovery Diode

    NASA Astrophysics Data System (ADS)

    Go, Tomio; Kanesawa, Kyousuke; Yamazaki, Nobuyuki; Mukaigawa, Seiji; Takaki, Koichi; Fujiwara, Tamiya

    Characteristics of inductive energy storage system pulsed power generator with semiconductor opening switch (SOS) diodes are investigated with focusing on an energy transfer efficiency from the generator to the resistive load. Fast recovery diodes VMI K100UF were used as SOS and were connected in series and/or in parallel to realize a large current and a high output voltage. The output voltage increases with increasing circuit inductance L and/or primary capacitor capacitance C. The reverse pumping time also increases with LC value and is saturated to 100 ns at LC=50×10-15 HF. The pulse width of the output voltage increases gradually with increasing value of the LC multiplication. The energy transfer efficiency of the generator to the resistive load has a maximum value of 71% at C=4nF and L=12.6μH when the load resistance is 122 Ω. This value is almost two times larger than 56 Ω of the surge impedance Zs=√L/C and much smaller than impedance of the SOS diodes after interrupting the circuit current. The maximum energy transfer efficiency decreases from 71 to 32% with decreasing LC value from 50×10-15 to 1.2×10-15 HF.

  16. A Study of the Dynamics of the Heme Pocket and C-helix in CooA upon CO Dissociation Using Time-Resolved Visible and UV Resonance Raman Spectroscopy.

    PubMed

    Otomo, Akihiro; Ishikawa, Haruto; Mizuno, Misao; Kimura, Tetsunari; Kubo, Minoru; Shiro, Yoshitsugu; Aono, Shigetoshi; Mizutani, Yasuhisa

    2016-08-18

    CooA is a CO-sensing transcriptional activator from the photosynthetic bacterium Rhodospirillum rubrum that binds CO at the heme iron. The heme iron in ferrous CooA has two axial ligands: His77 and Pro2. CO displaces Pro2 and induces a conformational change in CooA. The dissociation of CO and/or ligation of the Pro2 residue are believed to trigger structural changes in the protein. Visible time-resolved resonance Raman spectra obtained in this study indicated that the ν(Fe-His) mode, arising from the proximal His77-iron stretch, does not shift until 50 μs after the photodissociation of CO. Ligation of the Pro2 residue to the heme iron was observed around 50 μs after the photodissociation of CO, suggesting that the ν(Fe-His) band exhibits no shift until the ligation of Pro2. UV resonance Raman spectra suggested structural changes in the vicinity of Trp110 in the C-helix upon CO binding, but no or very small spectral changes in the time-resolved UV resonance Raman spectra were observed from 100 ns to 100 μs after the photodissociation of CO. These results strongly suggest that the conformational change of CooA is induced by the ligation of Pro2 to the heme iron. PMID:27457181

  17. Double-pulse laser-induced breakdown spectroscopy for trace element analysis in sintered iron oxide ceramics

    NASA Astrophysics Data System (ADS)

    Heilbrunner, H.; Huber, N.; Wolfmeir, H.; Arenholz, E.; Pedarnig, J. D.; Heitz, J.

    2012-01-01

    Double-pulse laser-induced breakdown spectroscopy (LIBS) is an emerging technique for accurate compositional analysis of many different materials. We present a systematic study of collinear double-pulse LIBS for analysis of the trace and side elements boron, manganese, copper, aluminum, titanium, silicon, chromium, nickel, potassium, and calcium in sintered iron oxide targets. The samples were ablated in air by single-pulse and double-pulse Nd:YAG laser radiation (6 ns pulse duration, laser wavelength of 532 nm) and spectra were recorded with an Echelle spectrometer equipped with an ICCD camera. We investigated the evolution of atomic and ionic line emission intensities for different interpulse delay times between the laser pulses (from 100 ns to 50 μs) and gate delays after the second laser pulse. We also varied the energy partition between the first and second laser pulse and the size of the irradiated spot at the sample surface. For the trace and side elements, we observed double-pulse LIBS signals that were enhanced as compared to single-pulse measurements depending on the interpulse delay time, the energy partition between the pulses, and the spot size. For the elements boron, copper, aluminum, titanium, chromium, potassium, and calcium limits of detection below 10 ppm were achieved.

  18. Energy Dispersive XAFS: Characterization of Electronically Excited States of Copper(I) Complexes

    PubMed Central

    2013-01-01

    Energy dispersive X-ray absorption spectroscopy (ED-XAS), in which the whole XAS spectrum is acquired simultaneously, has been applied to reduce the real-time for acquisition of spectra of photoinduced excited states by using a germanium microstrip detector gated around one X-ray bunch of the ESRF (100 ps). Cu K-edge XAS was used to investigate the MLCT states of [Cu(dmp)2]+ (dmp =2,9-dimethyl-1,10-phenanthroline) and [Cu(dbtmp)2]+ (dbtmp =2,9-di-n-butyl-3,4,7,8-tetramethyl-1,10-phenanthroline) with the excited states created by excitation at 450 nm (10 Hz). The decay of the longer lived complex with bulky ligands, was monitored for up to 100 ns. DFT calculations of the longer lived MLCT excited state of [Cu(dbp)2]+ (dbp =2,9-di-n-butyl-1,10-phenanthroline) with the bulkier diimine ligands, indicated that the excited state behaves as a Jahn–Teller distorted Cu(II) site, with the interligand dihedral angle changing from 83 to 60° as the tetrahedral coordination geometry flattens and a reduction in the Cu–N distance of 0.03 Å. PMID:23718738

  19. Application of the Wire Ablation Dynamics Model to the Design and Optimization of Wire Array Loads of Complex Geometry

    SciTech Connect

    Esaulov, A. A.; Kantsyrev, V. L.; Safronova, A. S.; Williamson, K. M.; Shrestha, I.; Osborne, G. C.

    2009-01-21

    The implosion dynamics of wire array loads of complex geometry, such as nested cylindrical and planar wire arrays, is significantly affected by the uneven current distribution between the array wires, which was considered previously in the Wire Dynamics Model (WDM) simulations. The novel Wire Ablation Dynamics Model (WADM) extends the formalism of the original WDM by including the dynamics of wire ablation. The WADM simulations demonstrate that the implosions of the arrays with higher masses are more ablation dominated. The WADM simulations of the implosions dynamics of nested wire arrays have been performed for the short pulse (100 ns) and long pulse (220 ns) regimes at COBRA generator. Another factor that affects the result of the trade between the ablation and implosion time scales is the form of the current pulse, which can be very different from the classical sine-square shape. The predictions of the array implosion times by the WADM are in very good agreement with the recent experiments at the COBRA and Zebra facilities.

  20. A Full Parallel Event Driven Readout Technique for Area Array SPAD FLIM Image Sensors

    PubMed Central

    Nie, Kaiming; Wang, Xinlei; Qiao, Jun; Xu, Jiangtao

    2016-01-01

    This paper presents a full parallel event driven readout method which is implemented in an area array single-photon avalanche diode (SPAD) image sensor for high-speed fluorescence lifetime imaging microscopy (FLIM). The sensor only records and reads out effective time and position information by adopting full parallel event driven readout method, aiming at reducing the amount of data. The image sensor includes four 8 × 8 pixel arrays. In each array, four time-to-digital converters (TDCs) are used to quantize the time of photons’ arrival, and two address record modules are used to record the column and row information. In this work, Monte Carlo simulations were performed in Matlab in terms of the pile-up effect induced by the readout method. The sensor’s resolution is 16 × 16. The time resolution of TDCs is 97.6 ps and the quantization range is 100 ns. The readout frame rate is 10 Mfps, and the maximum imaging frame rate is 100 fps. The chip’s output bandwidth is 720 MHz with an average power of 15 mW. The lifetime resolvability range is 5–20 ns, and the average error of estimated fluorescence lifetimes is below 1% by employing CMM to estimate lifetimes. PMID:26828490